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Electrical and Electronics Engineering publications abstract of: 04-2010 sorted by title, page: 8
» Deducing the USLE mathematical structure by dimensional analysis and self-similarity theory
Abstract:
The Universal Soil Loss Equation (USLE) was originally deduced by a statistical analysis of a large data set of soil loss measurements. The multiplicative structure of the model has been criticised due to the considerable interdependence between the variables. Using the soil erosion representative variables and the reference condition adopted in the USLE, the aim of this paper was to apply dimensional analysis and self-similarity theory to deduce the functional relationship among the selected variables. The analysis yielded a multiplicative equation, similar to the USLE. Therefore, this study suggested that the USLE has a logical structure with respect to the...
Autors: V., Ferro
Appeared in: Biosystems Engineering
Publication date: Apr 2010
Publisher: Elsevier B.V.
Full litterature document
 
» Deep Ice Stratigraphy and Basal Conditions in Central West Antarctica Revealed by Coherent Radar
Abstract:
We discuss results from a high-sensitivity, multichannel, very high frequency, and surface-based radar depth sounder/imager. The instrument was used to map deep internal layers and characterize basal conditions over a 240- grid in the vicinity of the West Antarctic Ice Sheet Divide ice core site. The ice thickness at the core site was found to be about 3470 m, and we detected internal layers to within 350 m of the ice/bed interface. Radar-detected layer stratigraphy does not show evidence of flow-induced disturbances that might complicate the depth–age relationship and the interpretation of climate history preserved in the ice. We also found that bed reflectivity over the region varies by more than 30 dB. Approximately 15 dB of this variability appears to be the result of transitions from a frozen to a thawed bed in a number of places. The remainder probably results from changes in bed roughness. Our data are important for planning drilling to the bed, as well as providing constraints and boundary conditions for regional ice-flow models.
Autors: Laird, C. M.;Blake, W. A.;Matsuoka, K.;Conway, H.;Allen, C. T.;Leuschen, C. J.;Gogineni, S.;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Apr 2010, volume: 7, issue:2, pages: 246 - 250
Publisher: IEEE
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» Deep-Tissue Dynamic Monitoring of Decubitus Ulcers: Wound Care and Assessment
Abstract:
The use of deep-tissue multiwavelength imaging is of paramount importance in clinical settings as a noninvasive solution to identify andmonitor the progression of decubitus ulcers. A point-of-care multiwavelength imager is being developed, whose utility results from the provision of important physiological characteristics and blood flow metrics via analysis of deep-tissue response to light. The noninvasive real-time monitoring and analysis of tissue focusing on wound imaging is integral, because it allows for quantitative in situ measurements that characterize tissue to assess the progress of either tissue healing or necrosis.
Autors: Moza, R.;DiMaio, J.Michael.;Melendez, J.;
Appeared in: IEEE Engineering in Medicine and Biology Magazine
Publication date: Apr 2010, volume: 29, issue:2, pages: 71 - 77
Publisher: IEEE
Full litterature document
 
» Defect-Tolerant Design and Optimization of a Digital Microfluidic Biochip for Protein Crystallization
Abstract:
Protein crystallization is a commonly used technique for protein analysis and subsequent drug design. It predicts the 3-D arrangement of the constituent amino acids, which in turn indicates the specific biological function of a protein. Protein crystallization experiments are typically carried out in well-plates in the laboratory. As a result, these experiments are slow, expensive, and error-prone due to the need for repeated human intervention. Recently, droplet-based “digital” microfluidics have been used for executing protein assays on a chip. Protein samples in the form of nanoliter-volume droplets are manipulated using the principle of electrowetting-on-dielectric. We present the design of a multi-well-plate microfluidic biochip for protein crystallization; this biochip can transfer protein samples, prepare candidate solutions, and carry out crystallization automatically. To reduce the manufacturing cost of such devices, we present an efficient algorithm to generate a pin-assignment plan for the proposed design. The resulting biochip enables control of a large number of on-chip electrodes using only a small number of pins. Based on the pin-constrained chip design, we present an efficient shuttle-passenger-like droplet manipulation method and test procedure to achieve high-throughput and defect-tolerant well loading.
Autors: Xu, T.;Chakrabarty, K.;Pamula, V. K.;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: Apr 2010, volume: 29, issue:4, pages: 552 - 565
Publisher: IEEE
Full litterature document
 
» Deform PF-MT: Particle Filter With Mode Tracker for Tracking Nonaffine Contour Deformations
Abstract:
We propose algorithms for tracking the boundary contour of a deforming object from an image sequence, when the nonaffine (local) deformation over consecutive frames is large and there is overlapping clutter, occlusions, low contrast, or outlier imagery. When the object is arbitrarily deforming, each, or at least most, contour points can move independently. Contour deformation then forms an infinite (in practice, very large), dimensional space. Direct application of particle filters (PF) for large dimensional problems is impractically expensive. However, in most real problems, at any given time, most of the contour deformation occurs in a small number of dimensions (“effective basis space”) while the residual deformation in the rest of the state space (“residual space”) is small. This property enables us to apply the particle filtering with mode tracking (PF-MT) idea that was proposed for such large dimensional problems in recent work. Since most contour deformation is low spatial frequency, we propose to use the space of deformation at a subsampled set of locations as the effective basis space. The resulting algorithm is called deform PF-MT. It requires significant modifications compared to the original PF-MT because the space of contours is a non-Euclidean infinite dimensional space.
Autors: Vaswani, N.;Rathi, Y.;Yezzi, A.;Tannenbaum, A.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Apr 2010, volume: 19, issue:4, pages: 841 - 857
Publisher: IEEE
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» Deformable dielectrics - optimization of heterogeneities
Abstract:
The modeling and the numerical simulation of deformable dielectrics are discussed in a coupled electro-mechanical framework. It is demonstrated how the Maxwell stress contributions can be implemented efficiently into a finite element method. By using numerical simulation, the electro-static contraction of a soft actuator is calculated and examined. The operational curve, i.e. the variation of the compression versus the applied electric field, is obtained for a capacitor-like setup using the neo-Hooke material model. Furthermore, the idea of introducing ceramic inclusions in the soft elastomer is discussed, which is shown to be capable of improving the efficiency of the actuator. By...
Autors: R., Mueller , B.X., Xu , D., Gross , M., Lyschik , D., Schrade , ...
Appeared in: International Journal of Engineering Science
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Degrees of Freedom of a Communication Channel: Using DOF Singular Values
Abstract:
A fundamental problem in any communication system is: given a communication channel between a transmitter and a receiver, how many “independent” signals can be exchanged between them? Arbitrary communication channels that can be described by linear compact channel operators mapping between normed spaces are examined in this paper. The (well-known) notions of degrees of freedom (DOF) at level and essential dimension of such channels are developed in this general setting. We argue that the DOF at level and the essential dimension fundamentally limit the number of independent signals that can be exchanged between the transmitter and the receiver. We also generalize the concept of singular values of compact operators to be applicable to compact operators defined on arbitrary normed spaces which do not necessarily carry a Hilbert space structure. We show how these generalized singular values, which we call DOF singular values, can be used to calculate the DOF at level and the essential dimension of compact operators that describe communication channels. We describe physically realistic channels that require such general channel models.
Autors: Somaraju, R.;Trumpf, J.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Apr 2010, volume: 56, issue:4, pages: 1560 - 1573
Publisher: IEEE
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» Delay Analysis for Wireless Networks With Single Hop Traffic and General Interference Constraints
Abstract:
We consider a class of wireless networks with general interference constraints on the set of links that can be served simultaneously at any given time. We restrict the traffic to be single-hop, but allow for simultaneous transmissions as long as they satisfy the underlying interference constraints. We begin by proving a lower bound on the delay performance of any scheduling scheme for this system. We then analyze a large class of throughput optimal policies which have been studied extensively in the literature. The delay analysis of these systems has been limited to asymptotic behavior in the heavy traffic regime and order results. We obtain a tighter upper bound on the delay performance for these systems. We use the insights gained by the upper and lower bound analysis to develop an estimate for the expected delay of wireless networks with mutually independent arrival streams operating under the well-known maximum weighted matching (MWM) scheduling policy. We show via simulations that the delay performance of the MWM policy is often close to the lower bound, which means that it is not only throughput optimal, but also provides excellent delay performance.
Autors: Gupta, G. R.;Shroff, N. B.;
Appeared in: IEEE/ACM Transactions on Networking
Publication date: Apr 2010, volume: 18, issue:2, pages: 393 - 405
Publisher: IEEE
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» Delay Constrained Multiplexing of Video Streams Using Dual-Frame Video Coding
Abstract:
We consider the multiplexing problem of transmitting multiple video source streams from a server over a shared channel. We use dual-frame video coding with high-quality Long-Term Reference (LTR) frames and propose multiplexing methods to reduce the sum of mean squared error for all the video streams. This paper makes several improvements to dual-frame video coding. A simple motion activity detection algorithm is used to choose the location of LTR frames as well as the number of bits given to such frames. An adaptive buffer-constrained rate-control algorithm is devised to accommodate the extra bits of the high-quality LTR frames. Multiplexing of video streams is studied under the constraint of a video encoder delay buffer. Using H.264/AVC, the results show considerable improvement over baseline schemes such as H.264 rate control when the video streams are encoded individually and over multiplexing methods proposed previously in the literature. The high-quality LTR frames are offset in time among different video streams. This provides the benefits of dual-frame coding with high-quality LTR frames while still fitting under the constraint of an output delay buffer.
Autors: Tiwari, M.;Groves, T.;Cosman, P. C.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Apr 2010, volume: 19, issue:4, pages: 1022 - 1035
Publisher: IEEE
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» Delay-tolerant decode-and-forward based cooperative communication over Ricean channels
Abstract:
In this paper, we propose a TDMA based simple transmission scheme, which overcomes the effect of the delays caused by the poor synchronization of the relaying nodes over Ricean channels. The proposed scheme is able to provide an optimized coding gain in unsynchronized cooperative networks as compared to the existing delay tolerant distributed space-time block codes.
Autors: Bhatnagar, M.R.;Hjørungnes, A.;Debbah, M.;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Apr 2010, volume: 9, issue:4, pages: 1277 - 1282
Publisher: IEEE
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» DEM-Aided Block Adjustment for Satellite Images With Weak Convergence Geometry
Abstract:
To acquire the largest possible coverage for environmental monitoring, it is important in most situations that the overlapping areas and the convergent angles of respective satellite images be small. The traditional bundle adjustment method used in aerial photogrammetry may not be the most suitable for direct orientation modeling in situations characterized by weak convergence geometry. We propose and compare three block adjustment methods for the processing of satellite images using the digital elevation model (DEM) as the elevation control. The first of these methods is a revised traditional bundle adjustment approach. The second is based on the direct georeferencing approach. The third is a rational function model with sensor-oriented rational polynomial coefficients. A collocation technique is integrated into all three methods to improve the positioning accuracy. Experimental results indicate that using the DEM as an elevation control can significantly improve the geometric accuracy as well as the geometric discrepancies between images. This is the case for all three methods. Moreover, the geometric performance of the three methods is similar. There is a significant improvement in geometric consistency between overlapping SPOT images with respect to single image adjustment for steep areas.
Autors: Teo, T.-A.;Chen, L.-C.;Liu, C.-L.;Tung, Y.-C.;Wu, W.-Y.;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Apr 2010, volume: 48, issue:4, pages: 1907 - 1918
Publisher: IEEE
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» Demagnetization process and hysteresis loops in perpendicularly oriented hard/soft trilayers
Abstract:
Nucleation and evolution of domain walls as well as the magnetic reversal process in perpendicularly oriented hard/soft trilayers have been investigated within a micromagnetic approach, concentrated on the situation with very thin hard layer. The formula for the nucleation field has been derived, which falls as the soft layer thickness rises. Negative nucleation field occurs at thick soft layer when the shape anisotropy surpasses the crystalline one, where the magnetization in the center of the soft layer obeys the coherent rotation model. The microscopic and macroscopic hysteresis loops have been calculated numerically, with the angular distribution of the magnetization between the nucleation and pinning fields obtained. The area of the hysteresis loop decreases while the coercivity mechanism changes from nucleation to pinning as the soft layer thickness increases. The effect of the hard layer thickness is contrary to that of the soft layer, however, the former affects the demagnetization process and hysteresis loops significantly only when the layers are thin enough.
Autors: Zhao, G. P.;Bo, N.;Zhang, H. W.;Feng, Y. P.;Deng, Y.;
Appeared in: Journal of Applied Physics
Publication date: Apr 2010, volume: 107, issue:8, pages: 083907 - 083907-6
Publisher: IEEE
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» Demand-Aware Content Distribution on the Internet
Abstract:
The rapid growth of media content distribution on the Internet in the past few years has brought with it commensurate increases in the costs of distributing that content. Can the content distributor defray these costs through a more innovative approach to distribution? In this paper, we evaluate the benefits of a hybrid system that combines peer-to-peer and a centralized client–server approach against each method acting alone. A key element of our approach is to explicitly model the temporal evolution of demand. In particular, we employ a word-of-mouth demand evolution model due to Bass to represent the evolution of interest in a piece of content. Our analysis is carried out in an order scaling depending on the total potential mass of customers in the market. Using this approach, we study the relative performance of peer-to-peer and centralized client–server schemes, as well as a hybrid of the two—both from the point of view of consumers as well as the content distributor. We show how awareness of demand can be used to attain a given average delay target with lowest possible utilization of the central server by using the hybrid scheme. We also show how such awareness can be used to take provisioning decisions. Our insights are obtained in a fluid model and supported by stochastic simulations.
Autors: Shakkottai, S.;Johari, R.;
Appeared in: IEEE/ACM Transactions on Networking
Publication date: Apr 2010, volume: 18, issue:2, pages: 476 - 489
Publisher: IEEE
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» Demonstration of Brillouin Distributed Discrimination of Strain and Temperature Using a Polarization-Maintaining Optical Fiber
Abstract:
Distributed discrimination of strain and temperature is demonstrated by localizing both the stimulated Brillouin scattering (SBS) and the dynamic acoustic grating generated in the SBS process in a polarization-maintaining fiber with a correlation-domain continuous-wave technique. A 12- strain resolution and 0.3 temperature resolution together with a 10-cm spatial resolution are experimentally validated.
Autors: Zou, W.;He, Z.;Hotate, K.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Apr 2010, volume: 22, issue:8, pages: 526 - 528
Publisher: IEEE
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» Demonstration of Low-Cost Uplink Transmission in a Coherent OCDMA PON Using Gain-Switched Fabry–Pérot Lasers With External Injection
Abstract:
We propose and demonstrate a simple and low-cost uplink transmission scheme for coherent optical code-division multiple access (OCDMA) passive optical networks (PONs), using gain-switched Fabry–Pérot (GS-FP) lasers with external injection as local light sources at optical network units. Experimental results based on the two-user 1.25-Gb/s OCDMA system confirm the feasibility of this scheme. The system performance is compared with that of the OCDMA system using a conventional mode-locked laser (MLL). The auto-correlation peak to the maximum wing level (P/W) ratio is also given as the central wavelength of the GS-FP laser varies. The present low-cost scheme is highly preferable for OCDMA PON applications.
Autors: Liu, J.;Lu, Y.;Guo, C.;Hong, X.;Xu, L.;He, S.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Apr 2010, volume: 22, issue:8, pages: 583 - 585
Publisher: IEEE
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» Demonstration of negative differential resistance in GaN/AlN resonant tunneling diodes at room temperature
Abstract:
GaN/AlN resonant tunneling diodes (RTD) were grown by metal-organic chemical vapor deposition (MOCVD) and negative differential resistance with peak-to-valley ratios as high as 2.15 at room temperature was demonstrated. Effect of material quality on RTDs’ performance was investigated by growing RTD structures on AlN, GaN, and lateral epitaxial overgrowth GaN templates. Our results reveal that negative differential resistance characteristics of RTDs are very sensitive to material quality (such as surface roughness) and MOCVD is a suitable technique for III-nitride-based quantum devices.
Autors: Vashaei, Z.;Bayram, C.;Razeghi, M.;
Appeared in: Journal of Applied Physics
Publication date: Apr 2010, volume: 107, issue:8, pages: 083505 - 083505-5
Publisher: IEEE
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» Dense Plasma Focus -Pinches for High-Gradient Particle Acceleration
Abstract:
The final -pinch stage of a dense plasma focus (DPF) could be used as a simple, compact, and potentially rugged plasma-based high-gradient accelerator with fields at the 100-MV/m level. In this paper, we review previously published experimental beam data that indicate the feasibility of such a DPF-based accelerator, qualitatively discuss the physical acceleration processes in terms of the induced voltages, and as a starting point, examine the DPF acceleration potential by numerically applying a self-consistent DPF system model that includes the induced voltage from both macroscopic and instability-driven plasma dynamics. Applications to the remote detection of high explosives and a multistaged acceleration concept are briefly discussed.
Autors: Tang, V.;Adams, M. L.;Rusnak, B.;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Apr 2010, volume: 38, issue:4, pages: 719 - 727
Publisher: IEEE
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» Density Functional Theory Study on Photophysical Properties of the Porphyrins Derivatives with Through-Bond Energy Transfer Characters
Abstract:
Density functional theory (DFT) calculations have been carried out on the electronic structures, electronic spectra, carrier injection and transport properties of a series of porphyrin derivatives, 5,15-di(R)porphyrin, 5,10,15,20-tetra(R)porphyrin, and Zn-5,10,15,20-tetra(R)porphyrin, namely, DCP, TCP, and ZCP (where R=carbazole); DMP, TMP, and ZMP (where R=N, N-dimethyl-phenyl); DQP, TQP, and ZQP (where R=2, 3, 6, 7-tetrahydro-1H, 5H-benzo[ij]puinolizine). The through-bond (TB) energy transfer process in these porphyrin derivatives has been verified by three aspects of characters, i.e. electronic structures, Dexter-type and Förster-type energy transfer. Moreover, the reasons for their high efficiency as red emitting materials have been revealed by the investigations of the ionization...
Autors: Xue-Feng, Ren , Ai-Min, Ren , Ji-Kang, Feng , Xin, Zhou
Appeared in: Organic Electronics
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Dependence of sensitivity of biosensor for carbon nanotube field-effect transistor with top-gate structures
Abstract:
In this study, we used biosensors that employ a top-gate-type carbon nanotube field-effect transistor (CNT-FET) for detecting target proteins in a solution. The dependence of the sensitivity of the biosensor on structural characteristics of the top gate, such as the thicknesses of its insulator and electrode and the relative permittivity of the insulator, was examined by simulations and by experiment which change the thickness of the insulator. Results of calculations performed by the finite element method showed that a thin insulator with a relative permittivity greater than 20 would lead to high sensitivity of the CNT-FET biosensor. Experimental investigation supported this result. The transconductance of a CNT-FET with a 20-nm-thick insulating layer was found to be approximately six times higher than that with 50-nm-thick and 80-nm-thick insulating layers. Moreover, the sensitivity of the CNT-FET biosensor with the 20-nm-thick insulating layer was also higher than that of a CNT-FET with a thicker insulating layer. By the experimental measurements, the influence of insulator thickness on the sensitivity of the biosensor was elucidated for the first time.
Autors: Abe, Masuhiro;Murata, Katsuyuki;Matsumoto, Kazuhiko;
Appeared in: Journal of Applied Physics
Publication date: Apr 2010, volume: 107, issue:8, pages: 084504 - 084504-4
Publisher: IEEE
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» Deployment of contextual corporate telco services based on protocol adaptation in the NGN environment
Abstract:
Deployment of contextual services is usually constrained to specific areas where contextual behavior can be obtained, mainly due to coverage limitations of context acquisition devices. Although end customers highly appreciate contextual services, those limitations make such services difficult to commercialize. In this article we present a practical deployment of a contextual service offered by a convergent telecommunications operator, whose functionality is to provide intelligent context-based call routing and rerouting, orchestrated from the operator's service layer. It is based on IMS control layer capabilities to properly capture the situation of the end user in a ubiquitous coverage area. The user's context is stored in a network-centric element in order to leverage that information across different services, optimizing the system by increasing the quality of the information captured and processed. This implementation proves that value-added contextual services may be built efficiently today using available products and protocols. Since contextual services will likely be a valuable part of a service provider's portfolio, this implementation can help creators of new contextual services to meet cost and time-to-market objectives.
Autors: Cadenas, A.;Sanchez-Esguevillas, A.;Carro, B.;
Appeared in: IEEE Communications Magazine
Publication date: Apr 2010, volume: 48, issue:4, pages: 34 - 40
Publisher: IEEE
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» Deposition of Functionalized Cr7Ni Molecular Rings on Graphite from the Liquid Phase
Abstract:
Graphite is a clean substrate and its nanostructures hold great potential for applications. Anchoring large molecules on graphite represents a challenge for several reasons that essentially rise from the planar bonds of the packed honeycomb structure of carbon. Here, a systematic investigation by AFM and XPS on different derivatives of molecular Cr7Ni rings deposited on highly oriented pyrolytic graphite (HOPG) is reported. Cr7Ni is emerging as a prototipical example of molecular antiferromagnet on which quantum phenomena and coherence have been demonstrated. For the deposition of Cr7Ni on HOPG, two strategies are adopted: 1) Cr7Ni rings are functionalized with extended alkyl/benzene terminations and 2) a self-assembled monolayer of alkyl chains with sulfonate terminations is deposited and then a cationic Cr7Ni derivative is used. In both cases the electronic bond with the carbon surface is soft, but the two-step procedure is efficient, albeit indirect, in sticking molecular Cr7Ni on HOPG. These strategies can be easily extended to deposit other complex molecular aggregates on graphite from the liquid phase.
Autors: Alberto Ghirri, Valdis Corradini, Christian Cervetti, Andrea Candini, Umberto del Pennino, Grigore Timco, Robin J. Pritchard, Christopher A. Muryn, Richard E. P. Winpenny, Marco Affronte
Appeared in: Advanced Functional Materials
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Depth Image-Based Temporal Error Concealment for 3-D Video Transmission
Abstract:
A depth image-based error concealment algorithm for 3-D video transmission is proposed, which utilizes the strong correlations between 2-D video and its corresponding the depth map. We first investigate the internal characteristics of the macroblock in the depth map, and then take advantage of these characteristics to recover accurately the lost motion vector for the corrupted blocks, with the joint consideration of the neighbor information and the corresponding depth. Experimental results show that the proposed method provides significant improvements in terms of both objective and subjective evaluations.
Autors: Liu, Y.;Wang, J.;Zhang, H.;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Apr 2010, volume: 20, issue:4, pages: 600 - 604
Publisher: IEEE
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» Derating of Multiphase Induction Machines Due to Supply Imbalance
Abstract:
Open-loop variable-voltage variable-frequency control should offer an effective control strategy in many applications of multiphase machines, but increasing the number of phases can make the machine more sensitive to imbalance in the supply voltage, causing unequal current sharing between phases. This paper uses simple expressions based on an extended symmetric-component approach to quantify the degree of current imbalance and provide a way of calculating the derating required. This paper shows that the additional stator copper losses are concentrated in the phase with the highest terminal voltage. However, the pulsating torques, rotor losses, and total stator losses due to supply imbalance in a multiphase machine are less than for the three-phase case. Experimental results for the same machine when connected with four and six phases show good agreement with the simple analysis method proposed. A more detailed generalized harmonic analysis algorithm is used to validate the torque and loss calculations.
Autors: Apsley, J. M.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Apr 2010, volume: 46, issue:2, pages: 798 - 805
Publisher: IEEE
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» Design and Analysis of 42-V Coreless Axial-Flux Permanent-Magnet Generators for Automotive Applications
Abstract:
This paper presents the design and analysis of a novel structure of an axial-flux permanent-magnet machine with ironless stator to generate sinusoidal electromotive force with very low harmonics. The structure is of a special design that is suitable for flux weakening in variable speeds. Flux weakening is done by a mechanical actuator to change the position of windings relative to each other. To confirm the machine performance and the design, analytical and three-dimensional finite-element numerical methods are implemented. The simulations results of the proposed generator coincide very well with the experimental results on a prototype 42-V system realized in the laboratory.
Autors: Javadi, S.;Mirsalim, M.;
Appeared in: IEEE Transactions on Magnetics
Publication date: Apr 2010, volume: 46, issue:4, pages: 1015 - 1023
Publisher: IEEE
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» Design and Analysis of a Grid-Connected Photovoltaic Power System
Abstract:
A grid-connected photovoltaic (PV) power system with high voltage gain is proposed, and the steady-state model analysis and the control strategy of the system are presented in this paper. For a typical PV array, the output voltage is relatively low, and a high voltage gain is obligatory to realize the grid-connected function. The proposed PV system employs a ZVT-interleaved boost converter with winding-coupled inductors and active-clamp circuits as the first power-processing stage, which can boost a low voltage of the PV array up to a high dc-bus voltage. Accordingly, an accurate steady-state model is obtained and verified by the simulation and experimental results, and a full-bridge inverter with bidirectional power flow is used as the second power-processing stage, which can stabilize the dc-bus voltage and shape the output current. Two compensation units are added to perform in the system control loops to achieve the low total harmonic distortion and fast dynamic response of the output current. Furthermore, a simple maximum-power-point-tracking method based on power balance is applied in the PV system to reduce the system complexity and cost with a high performance. At last, a 2-kW prototype has been built and tested to verify the theoretical analysis of the paper.
Autors: Yang, B.;Li, W.;Zhao, Y.;He, X.;
Appeared in: IEEE Transactions on Power Electronics
Publication date: Apr 2010, volume: 25, issue:4, pages: 992 - 1000
Publisher: IEEE
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» Design and Analysis of a Tunable Miniaturized-Element Frequency-Selective Surface Without Bias Network
Abstract:
A novel, tunable miniaturized-element frequency-selective surface that does not require additional bias networks is presented. This spatial filter is composed of two wire-grids printed on opposite sides of a substrate and connected to each other with an array of varactors using plated via holes. Varactor diodes are positioned between the grids. Via sections and metallic pads are fabricated and create a dc path for biasing the varactors with the grids themselves. This configuration eliminates the need for any additional network, and therefore resolves the design difficulties associated with the spurious response of the bias network. An equivalent circuit model is developed to facilitate the design procedure. Full-wave numerical simulations are used to validate the results based on the circuit model. Simulations show that by altering the capacitance of the varactors from 0.1 to 1 pF, a frequency tunability from 8 to 10 GHz with an almost constant bandwidth can be achieved.
Autors: Bayatpur, F.;Sarabandi, K.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Apr 2010, volume: 58, issue:4, pages: 1214 - 1219
Publisher: IEEE
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» Design and analysis of multi-user SDMA systems with noisy limited CSIT feedback
Abstract:
In this paper, we consider spatial-division multipleaccess (SDMA) systems with one base station with multiple antennae and a number of single antenna mobiles under noisy limited CSIT feedback. We propose a robust noisy limited feedback design for SDMA systems. Furthermore, we show that despite the noisy feedback, the average system goodput scales as O(nT)(1-ϵ)nT-1(C fb -log2(Nn)))and O(nT.log2 P) in the interference limited regime (C fb < (nT - 1) log2 P + log2 Nn) and noise-limited regime respectively.
Autors: Tianyu Wu;Lau, V.K.N.;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Apr 2010, volume: 9, issue:4, pages: 1446 - 1450
Publisher: IEEE
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» Design and Control of Concentric-Tube Robots
Abstract:
A novel approach toward construction of robots is based on a concentric combination of precurved elastic tubes. By rotation and extension of the tubes with respect to each other, their curvatures interact elastically to position and orient the robot's tip, as well as to control the robot's shape along its length. In this approach, the flexible tubes comprise both the links and the joints of the robot. Since the actuators attach to the tubes at their proximal ends, the robot itself forms a slender curve that is well suited for minimally invasive medical procedures. This paper demonstrates the potential of this technology. Design principles are presented and a general kinematic model incorporating tube bending and torsion is derived. Experimental demonstration of real-time position control using this model is also described.
Autors: Dupont, P. E.;Lock, J.;Itkowitz, B.;Butler, E.;
Appeared in: IEEE Transactions on Robotics
Publication date: Apr 2010, volume: 26, issue:2, pages: 209 - 225
Publisher: IEEE
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» Design and Development of Low-Loss Transformer for Powering Small Implantable Medical Devices
Abstract:
Small implantable medical devices, such as wireless capsule endoscopes, that can be swallowed have previously been developed. However, these devices cannot continuously operate for more than 8 h because of battery limitations; moreover, additional functionalities cannot be introduced. This paper proposes a design method for a high-efficiency energy transmission transformer (ETT) that can transmit energy transcutaneously to small implantable medical devices using electromagnetic induction. First, the authors propose an unconventional design method to develop such a high-efficiency ETT. This method can be readily used to calculate the exact transmission efficiency for changes in the material and design parameters (i.e., the magnetic material, transmission frequency, load resistance, etc.). Next, the ac-to-ac energy transmission efficiency is calculated and compared with experimental measurements. Then, suitable conditions for practical transmission are identified. A maximum efficiency of 33.1% can be obtained at a transmission frequency of 500 kHz and a receiving power of 100 mW for a receiving coil size of mm. Future design optimization is possible by using this method.
Autors: Shiba, K.;Morimasa, A.;Hirano, H.;
Appeared in: IEEE Transactions on Biomedical Circuits and Systems
Publication date: Apr 2010, volume: 4, issue:2, pages: 77 - 85
Publisher: IEEE
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» Design and Evaluation of a Dual Impedance-Adapting Power-Line Communications Coupler
Abstract:
Historically, the unpredictable on-off switching of loads has been a major obstacle to low-voltage power-line communications. Some researchers have gathered valuable data and have proposed statistical models in order to try and mitigate these sudden changes in access impedance. Others have proposed network conditioning in order to “block off” harsh loads from the power-line network by means of series filters. These filters are expensive, as they have to be rated at the typical current that is drawn by the load to be ‘blocked off’. Also, in many cases, these are the very loads than need to be monitored and controlled for home automation. This paper investigates the possibility of utilizing a simple, dual coupler to diminish the impact of switching loads on data transmission. First, the design of a suitable dual coupler is demonstrated, using a commercially available high-frequency transformer. Next, laboratory as well as live 220-V measurements are done for 50- modems at frequencies below 1 MHz. These measurements confirm that the proposed dual coupler can help to counter the impact of switching power-line loads by means of i) improved transmission when a certain network point is loaded and ii) more predictable (lower) power-line impedance levels—facilitating more accurate overall impedance adaptation.
Autors: Janse van Rensburg, P. A.;Ferreira, H. C.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Apr 2010, volume: 25, issue:2, pages: 667 - 673
Publisher: IEEE
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» Design and Field Experimentation of an Energy-Efficient Architecture for DTN Throwboxes
Abstract:
Disruption-tolerant networks (DTNs) rely on intermittent contacts between mobile nodes to deliver packets using a store-carry-and-forward paradigm. We earlier proposed the use of throwbox nodes, which are stationary, battery-powered nodes with storage and processing, to enhance the capacity of DTNs. However, the use of throwboxes without efficient power management is minimally effective. If the nodes are too liberal with their energy consumption, they will fail prematurely. However, if they are too conservative, they may miss important transfer opportunities, hence increasing lifetime without improving performance. In this paper, we present a hardware and software architecture for energy-efficient throwboxes in DTNs. We propose a hardware platform that uses a multitiered, multiradio, scalable, solar-powered platform. The throwbox employs an approximate heuristic for solving the NP-hard problem of meeting an average power constraint while maximizing the number of bytes forwarded by the throwbox. We built and deployed prototype throwboxes in UMass DieselNet, a bus-based DTN testbed. Through extensive trace-driven simulations and prototype deployment, we show that a single throwbox with a 270-cm solar panel can run perpetually while improving packet delivery by 37% and reducing message delivery latency by at least 10% in the network.
Autors: Banerjee, N.;Corner, M. D.;Levine, B. N.;
Appeared in: IEEE/ACM Transactions on Networking
Publication date: Apr 2010, volume: 18, issue:2, pages: 554 - 567
Publisher: IEEE
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» Design and implementation of a novel high-performance sensorless control system for interior permanent magnet synchronous motors
Abstract:
This study proposes a novel high-performance rotor position estimator for an interior permanent magnet synchronous motor (PMSM). By suitably processing the mathematical model of the motor, a systematic method of the rotor position estimating method has been developed. The proposed control system can be used in the space vector pulse-width modulation switching method, which is widely used in industry. By measuring the DC-bus voltage and the phase currents, a systematic rotor position estimator has been developed. Finally, the rotor position and rotor speed are obtained, and a closed-loop control system can be achieved. A digital signal processor, TMS 320F2812, is used to execute the estimating algorithm and control algorithm. As a result, the hardware is very simple. Several experimental results show that both the position control system and the adjustable speed control system are achieved. The system can be adjusted from 1 to 2000 r/min. In addition, by using the proposed position-loop H∞1 controller, the position control system can be achieved with satisfactory performance. This study proposes a new method for a sensorless interior PMSM control system.
Autors: Chen, J.-L.;Liu, T.-H.;Chen, C.-L.;
Appeared in: IET Electric Power Applications
Publication date: Apr 2010, volume: 4, issue:4, pages: 226 - 240
Publisher: IEEE
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» Design and implementations series V: IMS applications and support [Series Editorial]
Abstract:
The IEEE Communications Magazine editorial team characterizes Series and Feature Topics as covering either vertical or horizontal topics. A topic is vertical if it is focused on a particular communication technology (e.g., next-generation optical switching). A topic is horizontal if it focuses on some operational aspect that is common across many communications technologies, such as interoperability testing or performance testing. The Design and Implementation (D&I) Series is horizontal, as D&I articles are intended to teach industry professionals about building next-generation communications products and services, regardless of the specific technology area.
Autors: Moore, S.;
Appeared in: IEEE Communications Magazine
Publication date: Apr 2010, volume: 48, issue:4, pages: 24 - 25
Publisher: IEEE
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» Design and optimisation of Yagi-Uda antenna arrays
Abstract:
The geometry optimisation of linear and two-dimensional (2D) Yagi-Uda antenna arrays is presented. The objective from the optimisation is to increase the directivity and/or minimise the sidelobe level. The optimisation parameters are the lengths and/or the separations between the array elements for the linear array, and lengths and element locations for the 2D array. The current distribution over the array elements is found using the method of moments that takes into consideration mutual coupling between array elements. From the current distribution and the array geometry, the radiated electric field is computed, from which the directivity and other array parameters are calculated. The particle swarm optimisation (PSO) method is used in the optimisation process. Various numerical examples are presented and discussed, and the results are compared with other optimisation methods whenever possible.
Autors: Khodier, M.;Al-Aqil, M.;
Appeared in: IET Microwaves, Antennas & Propagation
Publication date: Apr 2010, volume: 4, issue:4, pages: 426 - 436
Publisher: IEEE
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» Design first
Abstract:
"Good design isn't born of marketing, it's created by designers." That was the conclusion of the jury for this year's iF product design awards from the International Forum Design as it announced this year's 50 gold award winners on the opening day of CeBit, the annual trade show for IT and consumer electronics in Hannover earlier this month.
Autors: Ross, D.;
Appeared in: Engineering & Technology
Publication date: Apr 2010, volume: 5, issue:5, pages: 26 - 27
Publisher: IEEE
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» Design Hardening of Nanometer SRAMs Through Transistor Width Modulation and Multi-Vt Combination
Abstract:
Memory design in the nanometer regime imposes specific restrictions to the cell layout structure requiring regular disposition of transistors to minimize the impact of process parameter variations. These layout restrictions invalidate many of the traditional design techniques oriented to improve cell immunity to radiation-induced events that, in turn, get worsened with technology scaling. We analyze two design alternatives to improve cell hardening compatible with regular cell layouts providing an extensive analysis to illustrate the benefits of each technique. One of the proposed solutions is based on transistor width modulation that provides an immunity enhancement at the cost of a moderate cell-size increase. The other solution is based on multithreshold voltage selection showing a moderate immunity improvement at the cost of no impact on the cell area. The combination of both techniques is shown to be optimum when considering other design metrics like static noise margin, read/write stability, access time, and leakage. Results are demonstrated on 90- and 65-nm commercial technologies.
Autors: Torrens, G.;Alorda, B.;Barceló, S.;Rosselló, J. L.;Bota, S. A.;Segura, J.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Apr 2010, volume: 57, issue:4, pages: 280 - 284
Publisher: IEEE
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» Design High-Efficiency Si Nanopillar-Array-Textured Thin-Film Solar Cell
Abstract:
In this letter, the electrical performance in terms of power conversion efficiency (PCE) of Si nanopillar (SiNP)-textured thin-film solar cell is investigated via simulation, where the SiNP physical dimensions were predetermined for optimized solar-energy absorption. Several key factors affecting PCE of the solar cell, e.g., the impact of Si quality in terms of minority carrier lifetime, emitter doping level, and emitter junction depth, is highlighted, and a practical guideline to design high-efficiency SiNP-textured thin-film solar cell is thus provided. The PCE of the structure under investigation can be significantly boosted, compared with the to-date reported Si thin-film solar cell.
Autors: Wong, S. M.;Yu, H. Y.;Li, J. S.;Zhang, G.;Lo, P. G. Q.;Kwong, D. L.;
Appeared in: IEEE Electron Device Letters
Publication date: Apr 2010, volume: 31, issue:4, pages: 335 - 337
Publisher: IEEE
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» Design issues and experimental studies of wireless LAN Mesh
Abstract:
Wireless mesh networking, as a low-cost and reliable technology for rapid network deployment, has attracted considerable attention from academia and standardization in the industry. The IEEE 802.11s standard defines a wireless LAN mesh using the IEEE 802.11 medium access control and physical layers, and is one of the most active standards with increasing commercial opportunities. This study presents the design and development of a WLAN mesh system conforming to the latest IEEE 802.11s draft amendment. Without costly hardware modifications, the proposed solution is a pure software extension for commercial off-the-shelf WLAN chipsets. This study constructs an experimental testbed, and evaluates issues such as the transmission reliability of mesh broadcast-type control messages and multichannel transmissions. Experimental results demonstrate that the delivery of mesh broadcast-type control messages, such as routing construction frames, using the multiple acknowledged unicast scheme improves mesh stability from an 86 to a 98 percent success ratio in a 16-node grid. Transmitting packets using a single radio interface switching between multiple channels reduces inter-flow interference and doubles the throughput in our testbed.
Autors: Lin, Ying-Dar;Tsao, Shiao-Li;Chang, Shun-Lee;Cheng, Shau-Yu;Ku, Chia-Yu;
Appeared in: IEEE Wireless Communications
Publication date: Apr 2010, volume: 17, issue:2, pages: 32 - 40
Publisher: IEEE
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» Design issues and experimental studies of wireless lan mesh [Accepted from Open Call]
Abstract:
Wireless mesh networking, as a low-cost and reliable technology for rapid network deployment, has attracted considerable attention from academia and standardization in the industry. The IEEE 802.11s standard defines a wireless LAN mesh using the IEEE 802.11 medium access control and physical layers, and is one of the most active standards with increasing commercial opportunities. This study presents the design and development of a WLAN mesh system conforming to the latest IEEE 802.11s draft amendment. Without costly hardware modifications, the proposed solution is a pure software extension for commercial off-the-shelf WLAN chipsets. This study constructs an experimental testbed, and evaluates issues such as the transmission reliability of mesh broadcast-type control messages and multichannel transmissions. Experimental results demonstrate that the delivery of mesh broadcast-type control messages, such as routing construction frames, using the multiple acknowledged unicast scheme improves mesh stability from an 86 to a 98 percent success ratio in a 16-node grid. Transmitting packets using a single radio interface switching between multiple channels reduces inter-flow interference and doubles the throughput in our testbed.
Autors: Lin, Ying-Dar;Tsao, Shiao-Li;Chang, Shun-Lee;Cheng, Shau-Yu;Ku, Chia-Yu;
Appeared in: IEEE Wireless Communications
Publication date: Apr 2010, volume: 17, issue:2, pages: 32 - 40
Publisher: IEEE
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» Design Issues and Implementations for Floating-Point Divide–Add Fused
Abstract:
This brief presents a dedicated unit for the combined operation of floating-point (FP) division followed by addition/subtraction—the divide–add fused (DAF). The goal of this unit is to increase the performance and the accuracy of applications where this combined operation is frequent, such as the interval Newton's method or the polynomial approximation. The proposed DAF unit presents a similar architecture to the FP multiply-accumulate units. The main difference is represented by the divider, which is implemented using digit-recurrence algorithms. An important design tradeoff regarding DAF is represented by the number of required quotient bits. We present the impact of the adopted number of quotient bits on accuracy, cost, and performance. Consequently, two implementations are proposed: one pro-accuracy and one pro-performance. We show that the proposed implementations have better accuracy with respect to the solution based on two distinct units: an FP divider and an FP adder. The implementation suitable for lower latency presents the best cost-performance tradeoff.
Autors: Amaricai, A.;Vladutiu, M.;Boncalo, O.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Apr 2010, volume: 57, issue:4, pages: 295 - 299
Publisher: IEEE
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» Design of n-bit digital phase shifter using single CRLH TL unit cell
Abstract:
A technique is presented that uses a single composite right/left-handed transmission line (CRLH TL) unit cell to design n-bit digital phase shifters with small sizes, high power-handling capacities, low insertion losses, and arbitrary phase-shift ranges and step sizes. A 3-bit phase shifter with an operating frequency band of 9¿10 GHz has been designed and fabricated for study.
Autors: Zhang, J.;Cheung, S.W.;Yuk, T.I.;
Appeared in: Electronics Letters
Publication date: Apr 2010, volume: 46, issue:7, pages: 506 - 508
Publisher: IEEE
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» Design of a 79 dB 80 MHz 8X-OSR Hybrid Delta-Sigma/Pipelined ADC
Abstract:
A hybrid delta-sigma/pipelined modulator is presented in this paper. The proposed modulator takes advantage of the high resolution and distributed pipelined quantization, and combines it with the noise shaping property of a delta-sigma modulator. As a result, gain, swing, and slew requirements of the integrators are significantly reduced. The modulator also makes use of the latency in the pipelined quantization to enhance noise shaping. These advantages lead to less power dissipation, increased stability, and higher resolution. The prototype chip is implemented in a 0.18 m CMOS process. With an 80 MHz clock, and an oversampling ratio of 8 (5 MHz bandwidth), the measured dynamic range and SNDR of this prototype IC are 79 dB and 75.4 dB.
Autors: Rajaee, O.;Musah, T.;Maghari, N.;Takeuchi, S.;Aniya, M.;Hamashita, K.;Moon, U.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Apr 2010, volume: 45, issue:4, pages: 719 - 730
Publisher: IEEE
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» Design of a High-Speed Motor Bus Transfer System
Abstract:
This paper addresses the design of a high-speed motor bus transfer system for power-generating plants and industrial facilities where motor loads require comprehensive source transfer strategies during transfer of the load from one source to another. Motor bus transfer schemes are needed not only to maintain process continuity but also to transfer sources in such a manner to prevent damage to the motors and connected loads. The motor bus frequency and voltage decay rapidly upon disconnection from the main source. This paper proposes a digital signal processing algorithm that can measure the magnitude and phase angle of the decaying bus voltage accurately while measuring the auxiliary-source voltage magnitude and phase angle at rated frequency. This paper details an algorithm to predict the phase coincidence between the motor bus voltage and the auxiliary-source voltage. The algorithm uses delta frequency, the rate of change of delta frequency, and breaker closing time to predict the phase coincidence. This paper also details the implementation of the motor bus transfer scheme that includes fast, in-phase, and residual transfer methods. The results of some real-time transfer cases are also included.
Autors: Yalla, M. V. V. S.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Apr 2010, volume: 46, issue:2, pages: 612 - 619
Publisher: IEEE
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» Design of a laser-assisted tomographic atom probe at Münster University
Abstract:
To benefit from the latest technical improvements in atom probe analysis, a new tomographic atom probe has been built at the University of Münster, Germany. The instrument utilizes a femtosecond laser system with a high repetition rate combined with the ability of using a micrometer-sized extraction electrode and a wide angle configuration. Since field evaporation is triggered by laser pulses instead of high-voltage pulses, the instrument offers the ability to expand the range of analyzed materials to poorly conducting or insulating materials such as oxides, glasses, ceramics, and polymeric materials. The article describes the design of the instrument and presents characterizing measurements on metals, semiconductors, and oxide ceramic.
Autors: Schlesiger, Ralf;Oberdorfer, Christian;Wurz, Roland;Greiwe, Gerd;Stender, Patrick;Artmeier, Michael;Pelka, Patrick;Spaleck, Frank;Schmitz, Guido;
Appeared in: Review of Scientific Instruments
Publication date: Apr 2010, volume: 81, issue:4, pages: 043703 - 043703-8
Publisher: IEEE
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» Design of a Normal Stress Electromagnetic Fast Linear Actuator
Abstract:
This paper describes the design of a normal stress electromagnetic linear actuator for fast tool servos during nonrotationally symmetric diamond turning. By using the permanent magnet as the biasing flux generator and the total armature pole surface for force generation, the actuator is designed to achieve both linear operation characteristics and high acceleration. A design methodology is presented, which is based on analytical and finite element method magnetic circuit analysis. For design optimization, a new criterion, high actuating force density, is introduced. Based on the optimized structural parameters and the strategy of design for manufacturing, a novel axisymmetric fast linear actuator is developed that has a stroke of 100 and 500 G acceleration. The linearity of the actuating force versus both the excitation current and the armature displacement is experimentally demonstrated. It is shown that the experimental and calculated results agree well with each other.
Autors: Wu, D.;Xie, X.;Zhou, S.;
Appeared in: IEEE Transactions on Magnetics
Publication date: Apr 2010, volume: 46, issue:4, pages: 1007 - 1014
Publisher: IEEE
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» Design of a novel band-notched slot patch antenna for UWB communication systems
Abstract:
A novel band-notched elliptical slot antenna is presented for ultra-wideband (UWB) applications. The proposed antenna is fed via a microstrip-line that is connected to an elliptical shaped patch which incorporates an inverted-U slot. The inverted-U slot behaves like a band reject network designed to eliminate 5.15-5.825 GHz band-limited by IEEE 802.11a and HIPERLAN/2. Effects of varying the inverted-U shaped slot parameters on the antenna's performance show that notch band can be finely tuned. The antenna with optimal parameters was realized and its performance measured. The antenna was fabricated on a RT/duroid 6006 that has a thickness of 1.27 mm and a relative permittivity of 6.15. The size of the actual antenna is 50 × 50 mm2. The radiation characteristics of the proposed antenna satisfy UWB system requirements. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1599-1603, 2010; DOI 10.1002/mop.25237
Autors: M. Naser-Moghadasi, G. R. DadashZadeh, A.-A. Kalteh, Bal S. Virdee
Appeared in: Microwave and Optical Technology Letters
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Design of a Robust Multi-Channel Timing Recovery System With Imperfect Channel State Information for 10GBASE-T
Abstract:
The interdependence among multiple channels and the interaction between timing and equalization loops bring new challenges to the design of a multi-channel symbol timing recovery (STR) system for 10GBASE-T. In addition, the nonlinear Tomlinson–Harashima precoding (THP) technique used in the 10GBASE-T system is vulnerable to the imperfect channel state information (CSI). In this paper, we address the problem of timing inaccuracy caused by imperfect CSI and the problem of extracting correct timing information in the presence of channel-interdependence and loop-interaction for 10GBASE-T. This paper proposes a novel averaged-sampling-phase (ASP) hybrid STR scheme, which aligns the sampling clock phase of a single phase-locked loop (PLL) with an average value of the timing information provided by each wire pair so that the impact of the noisy timing information resulting from the imperfect CSI and the timing jitter of the single PLL is reduced. Moreover, a three-phase timing recovery strategy based on our architecture is also designed to correctly extract the timing information and effectively mitigate the loop-interaction. Simulation results demonstrate that the proposed multi-channel STR provides a complete loop-timed solution for 10GBASE-T and achieves a superior performance over conventional approaches in terms of robustness and timing jitter.
Autors: Chien, Y.-R.;Mao, W.-L.;Tsao, H.-W.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Apr 2010, volume: 57, issue:4, pages: 886 - 896
Publisher: IEEE
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» Design of a substrate integrated waveguide modified R-KR lens for millimetre-wave application
Abstract:
In this study, a new type of substrate integrated waveguide (SIW) beamforming network (BFN) based on the principle of the modified R-KR lens has been proposed and experimentally verified. Through the detailed analysis of such a structure, a prototype lens with 15 input ports is implemented together with an SIW slot array antenna at 30 GHz, which is able to cover a wide angle of (-59°, 59°) with its 3 dB beam-width. The measured radiation efficiencies of the lens excited at different ports range from 21.6 to 40.8%. This type of BFN takes the advantages of low profile, low cost and high performance, and may be applied to millimetrewave mobile communications and radars with beam switching technology.
Autors: Cheng, Y.J.;Hong, W.;Wu, K.;
Appeared in: IET Microwaves, Antennas & Propagation
Publication date: Apr 2010, volume: 4, issue:4, pages: 484 - 491
Publisher: IEEE
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» Design of a Tunable All-Digital UWB Pulse Generator CMOS Chip for Wireless Endoscope
Abstract:
A novel tunable all-digital, ultrawideband pulse generator (PG) has been implemented in a standard 0.18- m complementary metal–oxide semiconductor (CMOS) process for implantable medical applications. The chip shows that an ultra-low dynamic energy consumption of 27 pJ per pulse without static current flow at a 200-MHz pulse repetition frequency (PRF) with a 1.8-V power supply and low area of 90 50 m . The PG generates tunable pulsewidth, amplitude, and transmit (Tx) power by using simple circuitry, through precise timing control of the H-bridge output stage. The all-digital architecture allows easy integration into a standard CMOS process, thus making it the most suitable candidate for in-vivo biotelemetry applications.
Autors: Kim, C.;Nooshabadi, S.;
Appeared in: IEEE Transactions on Biomedical Circuits and Systems
Publication date: Apr 2010, volume: 4, issue:2, pages: 118 - 124
Publisher: IEEE
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» Design of an atomic layer deposition reactor for hydrogen sulfide compatibility
Abstract:
A customized atomic layer deposition (ALD) reactor was designed with components compatible with hydrogen sulfide (H2S) chemistry. H2S is used as a reactant for the ALD of metal sulfides. The use of H2S in an ALD reactor requires special attention to safety issues due to its highly toxic, flammable, and corrosive nature. The reactor was designed with respect to materials compatibility of all wetted components with H2S. A customized safety interlock system was developed to shut down the system in the event of toxic gas leakage, power outage, loss of building ventilation or compressed air pressure. ALD of lead sulfide (PbS) and zinc sulfide (ZnS) were demonstrated with no chemical contamination or detectable release of H2S.
Autors: Dasgupta, Neil P.;Mack, James F.;Langston, Michael C.;Bousetta, Al;Prinz, Fritz B.;
Appeared in: Review of Scientific Instruments
Publication date: Apr 2010, volume: 81, issue:4, pages: 044102 - 044102-6
Publisher: IEEE
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» Design of asymmetrical spurline filter for a high power sic MESFET class-E power amplifier
Abstract:
An asymmetrical spurline filter (ASF) with dual-bandgap characteristics is designed and applied as the load network of the class-E power amplifier to improve the output power and efficiency. Meanwhile, an equivalent circuit model is built for the proposed ASF based on two LCR resonators. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1650-1652, 2010; DOI 10.1002/mop.25260
Autors: Li Wang, Wenhua Chen, Peng Wang, Xin Xue, Jiaxing Dong, Zhenghe Feng
Appeared in: Microwave and Optical Technology Letters
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Design of compact bandpass filter with improved selectivity using source-load coupling
Abstract:
A compact planar bandpass filter with improved selectivity using source¿load coupling is proposed. The new filter consists of quarterwavelength resonators and short-ended feedlines. An extra transmission zero is produced near the passband owing to the source¿ load coupling, which can improve the skirt-selectivity of the filter, and quarter-wavelength resonators are used to enhance the rejection level around the second harmonic. Both simulated and measured results with good agreement are presented.
Autors: Dai, G.L.;Guo, Y.X.;Xia, M.Y.;
Appeared in: Electronics Letters
Publication date: Apr 2010, volume: 46, issue:7, pages: 505 - 506
Publisher: IEEE
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» Design of Compact Differential Dual-Frequency Antenna With Stacked Patches
Abstract:
A compact differential dual-frequency antenna with stacked configuration is described. Compared with the conventional stacked dual-frequency antenna, the radiating element with a half guided wavelength is distributed on two layers and connected through via holes, thus the dimension of the antenna is reduced effectively. In order to improve the bandwidth at the first resonant frequency , a reflecting board is introduced and connected with the ground plane through three via holes. As a result, a new resonant frequency closing to can be excited and the bandwidth at is enhanced. Both differential antennas with and without the reflecting board are fabricated and measured. The realized antennas have a compact size of 15 mm 15 mm, which equals to ( , the guided wavelength at ). Experimental results show that the proposed antenna can operate at 2.4 GHz and 5.2 GHz bands. Good agreement between the simulated and measured results is obtained.
Autors: Han, L.;Zhang, W.;Chen, X.;Han, G.;Ma, R.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Apr 2010, volume: 58, issue:4, pages: 1387 - 1392
Publisher: IEEE
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» Design of compact microstrip band-pass filter with ultra-wide stopband
Abstract:
In this article, a microstrip band-pass filter with compact structure and ultra-wide stopband using quarter-wavelength stepped impedance resonators is proposed.Because of the optimal design for stepped impedance resonators, circuit size is reduced and harmonic response is suppressed. To suppress the higher resonant modes further, two open stubs connected to the input/output ports are used to achieve an ultra-wide stopband. The design procedure and additional lateral-resonated response are discussed in detail. As the presence of the two attenuation poles are around the passband edge, high selectivity and good performance is realized. The proposed filter with a fundamental frequency f0 of 0.9 GHz, measured insertion loss of less than 1.5 dB, return loss of better than 16 dB, and wide stopband up to 19 f0 is demonstrated. The stopband level is lower than 23 dB from 1.1 GHz up to 17.1 GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1603-1606, 2010; DOI 10.1002/mop.25238
Autors: Ko-Wen Hsu, Wen-Hua Tu
Appeared in: Microwave and Optical Technology Letters
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Design of differential low-noise amplifier with cross-coupled-SCR ESD protection scheme
Abstract:
The pin-to-pin electrostatic discharge (ESD) stress was one of the most critical ESD events for differential input pads. The pin-to-pin ESD issue for a differential low-noise amplifier (LNA) was studied in this work. A new ESD protection scheme for differential input pads, which was realized with cross-coupled silicon-controlled rectifier (SCR), was proposed to protect the differential LNA. The cross-coupled-SCR ESD protection scheme was modified from the conventional double-diode ESD protection scheme without adding any extra device. The SCR path was established directly from one differential input pad to the other differential input pad in this cross-coupled-SCR ESD protection scheme, so...
Autors: Chun-Yu, Lin , Ming-Dou, Ker , Yuan-Wen, Hsiao
Appeared in: Microelectronics Reliability
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Design of DOE-Based Automatic Process Controller With Consideration of Model and Observation Uncertainties
Abstract:
Robust parameter design (RPD) has been widely used as a cost-effective tool in quality control to reduce variability, in which the controllable factors are set to minimize the variability of response variables due to noise factors, assuming their distributions are known. It is essentially an offline tool without considering that some noise factors can be measured online. Recently, the concept of design of experiment (DOE)-based automatic process control (APC) has been proposed for online process control based on regression models obtained from DOE and with consideration of the online measurement of noise factors. The existing literature investigates the DOE-based APC with assumption that both regression models and the online noise measurement are precisely known, which limits the applicability of the technique. This paper develops the DOE-based APC scheme that considers both the observation and the modeling uncertainties. The controller is implemented under two APC strategies, i.e., cautious control strategy and certainty equivalence control strategy. The comparison among online APC and robust design approaches demonstrates that automatic controller with consideration of both uncertainties can achieve better process performance than conventional design, and is more stable than normal DOE-based APC controllers. The proposed approach is illustrated using an industrial process.
Autors: Zhong, J.;Shi, J.;Wu, J. C. F.;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Apr 2010, volume: 7, issue:2, pages: 266 - 273
Publisher: IEEE
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» Design of Dual-Passband Microstrip Bandpass Filters With Multi-Spurious Suppression
Abstract:
A systematic design method for microstrip bandpass filters with both dual-passband response and multi-spurious suppression is proposed in this letter. The filter is composed of stepped impedance resonators (SIRs). A novel asymmetric SIR structure is proposed to effectively increase the degree of freedom in the dual-passband bandwidth design. As a consequence, the transmission zero of the coupling stage could be used to suppress the unwanted higher order spurious responses. A complete design procedure considering both the synthesis of passband responses and the suppression of spurious responses is also depicted in detail. A fifth order filter is designed and fabricated to demonstrate this idea. The measured results show that the upper stopband can have an attenuation level near 30 dB up to more than 20 GHz (8.16 ).
Autors: Jiang, M.;Chang, L.-M.;Chin, A.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Apr 2010, volume: 20, issue:4, pages: 199 - 201
Publisher: IEEE
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» Design of plasmonic near field plate at optical frequency
Abstract:
We propose a design of near field plate for deep subwavelength super-focusing at optical frequency. The method used antisymmetric surface plasmon mode to generate abrupt π phase change within small fraction of a wavelength, while varied thin metallic film thickness to control the amplitude profile of the near field distribution. The numerical simulation result shows a λ/5 resolution at focus plane for the designed near field plate at the wavelength of 1550 nm, which is due to the superposition of the near field phase and amplitude distribution.
Autors: Shi, Haofei;Jay Guo, L.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:14, pages: 141107 - 141107-3
Publisher: IEEE
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» Design of Regular Wavelets Using a Three-Step Lifting Scheme
Abstract:
We propose structural multidimensional multichannel filter banks with desirable numbers of vanishing moments for the analysis and synthesis banks. For a two-channel filter bank, we use a three-step lifting scheme as opposed to the conventional two-step lifting method in order to provide more symmetry between the analysis and synthesis filters. We show that the resulting filters have more regularity, lower frame bounds ratio, and better frequency selectivity. We also extend our design to a general multichannel framework. Three steps of lifting scheme provides us a degree of freedom which we can benefit from toward a more flexible design.
Autors: Eslami, R.;Radha, H.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Apr 2010, volume: 58, issue:4, pages: 2088 - 2101
Publisher: IEEE
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» Design of small ACS-fed band-notch UWB monopole antenna using particle swarm optimization
Abstract:
This article presents, asymmetric coplanar strip fed half monopole UWB antenna to cover the ultra-wideband frequency operation. The antenna has staircase shape and very small volume (12 × 21 × 1 mm3). The band-rejection operation achieve at the WLAN (5.15-5.85 GHz) band by adding spiral defected radiator structure. Particle swarm optimization algorithm is employed to achieve ultra-wide band and band-rejection characteristics. The measured frequency response shows an impedance bandwidth of 9 GHz or 120% over 3-12 GHz for VSWR < 2. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1510-1513, 2010; DOI 10.1002/mop.25269
Autors: S. Soltani, M.N. Azarmanesh, P. Lotfi
Appeared in: Microwave and Optical Technology Letters
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Design tool to express failure detection protocols
Abstract:
Failure detection protocols ¿ a fundamental building block for crafting fault-tolerant distributed systems ¿ are in many cases described by their authors making use of informal pseudo-codes of their conception. Often these pseudo-codes use syntactical constructs that are not available in COTS programming languages such as C or C++. This translates into informal descriptions that call for ad hoc interpretations and implementations. Being informal, these descriptions cannot be tested by their authors, which may translate into insufficiently detailed or even faulty specifications. This study tackles this problem by introducing a formal syntax for those constructs and a C library that implements them ¿ a tool set to express and reason about failure detection protocols. The resulting specifications are longer but non-ambiguous, and eligible for becoming a standard form.
Autors: Florio, V.D.;Blondia, C.;
Appeared in: IET Software
Publication date: Apr 2010, volume: 4, issue:2, pages: 119 - 133
Publisher: IEEE
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» Design, assembly and reliability of large die and fine-pitch Cu/low-k flip chip package
Abstract:
This paper reports the design, assembly and reliability assessment of 21×21mm2 Cu/low-k flip chip (65nm node) with 150?m bump pitch and high bump density. To reduce the stress from the solder bump pad to low-k layers, Metal Redistribution Layer (RDL) and Polymer Encapsulated Dicing Lane (PEDL) are applied to the Cu/low-k wafer. Lead-free Sn2.5Ag, high-lead Pb5Sn and Cu-post/Sn37Pb bumps are evaluated as the first-level interconnects. It is found that the flip chip assembly of high-lead bumped test vehicle requires the right choice of flux and good alignment between the high-lead solder bumps and substrate pre-solder alloy to ensure proper solder...
Autors: Yue Ying, Ong , Soon Wee, Ho , Kripesh, Vaidyanathan , Vasarla Nagendra, Sekhar , Ming Chinq, Jong , ...
Appeared in: Microelectronics Reliability
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Design, fabrication and characterization of a latching acceleration switch with multi-contacts independent to the proof-mass
Abstract:
An acceleration latching switch with independent multi-contacts is presented in this paper. All the contacts and their beams are independent to the proof-mass so as to prevent the contacts from the impact resulting from the rebound or vibration of the proof mass once the switch is latched. Moreover, multiple contacts are used in order to get highly reliable contact, to lower the contact resistance and to increase the maximum allowable current. The switch was fabricated by low-cost two-mask silicon on glass process and tested. The latching shock is 4500 G and the response time is less than 0.1ms. The contact...
Autors: Z.Y., Guo , Z.C., Yang , L.T., Lin , Q.C., Zhao , H.T., Ding , ...
Appeared in: Sensors and Actuators A: Physical
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Design, Fabrication, and Characterization of CMOS MEMS-Based Thermoelectric Power Generators
Abstract:
This paper presents the design, modeling, fabrication, and characterization of CMOS microelectromechanical-systems-based thermoelectric power generators (TPGs) to convert waste heat into a few microwatts of electrical power. Phosphorus and boron heavily doped polysilicon thin films are patterned and electrically connected to consist thermopiles in the TPGs. To optimize heat flux, the thermal legs are embedded between the top and bottom vacuum cavities, which are sealed on the wafer level at low temperature. A heat-sink layer is coated on the cold side of the device to effectively disperse heat from the cold side of the device to ambient air. The peripheral cavity is designed to isolate heat from the surrounding silicon substrate. Both simulation and experiments are implemented to validate that the energy conversion efficiency is highly improved due to the aforementioned three unique designs. The device has been fabricated by a CMOS-compatible process. Properties of thermoelectric material, such as the Seebeck coefficient, electrical resistivity, and specific contact resistance are measured through test structures. For a device in the size of 1 and with a 5-K temperature difference across the two sides, the open-circuit voltage is 16.7 V and the output power is 1.3 under matched load resistance. Such energy can be efficiently accumulated as useful electricity over time and can prolong the battery life. [2009-0066]
Autors: Xie, J.;Lee, C.;Feng, H.;
Appeared in: Journal of Microelectromechanical Systems
Publication date: Apr 2010, volume: 19, issue:2, pages: 317 - 324
Publisher: IEEE
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» Designed Multifunctional Nanocomposites for Biomedical Applications
Abstract:
The assembly of multifunctional nanocomposite materials is demonstrated by exploiting the molecular sieving property of SBA-16 nanoporous silica and using it as a template material. The cages of the pore networks are used to host iron oxide magnetic nanoparticles, leaving a pore volume of 0.29 cm3 g-1 accessible for drug storage. This iron oxide-silica nanocomposite is then functionalized with amine groups. Finally the outside of the particle is decorated with antibodies. Since the size of many protein molecules, including that of antibodies, is too large to enter the pore system of SBA-16, the amine groups inside the pores are preserved for drug binding. This is proven using a fluorescent protein, fluorescein-isothiocyanate-labeled bovine serum albumin (FITC-BSA), with the unreacted amine groups inside the pores dyed with rhodamine B isothiocyanate (RITC). The resulting nanocomposite material offers a dual-targeting drug delivery mechanism, i.e., magnetic and antibody-targeting, while the functionalization approach is extendable to other applications, e.g., fluorescence-magnetic dual-imaging diagnosis.
Autors: Humphrey H. P. Yiu, Hong-jun Niu, Ellen Biermans, Gustaaf van Tendeloo, Matthew J. Rosseinsky
Appeared in: Advanced Functional Materials
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Designing for Discovery
Abstract:
As many have observed, sources of data are increasing exponentially and old methods of transmitting knowledge cannot keep up. Search technology has arisen to address this problem, but how best to use that technology remains an unsolved problem. Most computer users know how to go to Google or other search engines, enter search terms, and browse through results. Few user interface designers, however, know how to incorporate effective search technology into their designs. Search Patterns: Design for Discovery, by Peter Morville and Jeffery Callender, addresses that problem.
Autors: Mateosian, Richard;
Appeared in: IEEE Micro
Publication date: Apr 2010, volume: 30, issue:2, pages: 90 - 92
Publisher: IEEE
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» Designing for Discovery [review of "Search Patterns" Design for Discovery" (Morville, P. and Callender, J.; 2010)]
Abstract:
As many have observed, sources of data are increasing exponentially and old methods of transmitting knowledge cannot keep up. Search technology has arisen to address this problem, but how best to use that technology remains an unsolved problem. Most computer users know how to go to Google or other search engines, enter search terms, and browse through results. Few user interface designers, however, know how to incorporate effective search technology into their designs. Search Patterns: Design for Discovery, by Peter Morville and Jeffery Callender, addresses that problem.
Autors: Mateosian, Richard;
Appeared in: IEEE Micro
Publication date: Apr 2010, volume: 30, issue:2, pages: 90 - 92
Publisher: IEEE
Full litterature document
 
» Detecting defects in outdoor non-ceramic insulators using near-field microwave non-destructive testing
Abstract:
This paper presents a novel near-field microwave nondestructive testing technique for defect detection in non-ceramic insulators (NCI). In this work, distribution class 33 kV NCI samples with no defects, air voids in silicone rubber, cracks in the fiberglass core and small metallic inclusion between the fiber core and shank were inspected. The microwave inspection system utilizes an open-ended rectangular waveguide sensor operating in the near-field at a frequency of 24 GHz. The used inspection system is simple, safe and relatively inexpensive. A data acquisition system was used to record the measured data. The results showed that all defects were repeatedly detected with high sensitivity. Line scans of the samples were obtained revealing the presence of different defects and their location. The technique also demonstrated ability to detect thickness variations in the silicon rubber shank.
Autors: Qaddoumi, Nasser;El-Hag, Ayman H.;Hosani, Mohamed Al;Mansouri, Ibrahim Al;Ghufli, Hamad Al;
Appeared in: IEEE Transactions on Dielectrics and Electrical Insulation
Publication date: Apr 2010, volume: 17, issue:2, pages: 402 - 407
Publisher: IEEE
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» Detection of Active Wildland Fires Using Multitemporal MODIS Images
Abstract:
The fire fractional area and radiances at 4 and 11 of active fires in the boreal forests in Siberia and Mongolia were estimated using Advanced Spaceborne Thermal Emission and Reflection Radiometer images. In addition, a stochastic fire model was constructed. The efficiency of a biband threshold method used for detecting active fires on the basis of the thermal anomaly obtained from multitemporal Moderate Resolution Imaging Spectroradiometer (MODIS) images was evaluated using the stochastic fire model. The simulation results of fire detection indicated that the aforementioned method accurately detected 80% of the fire pixels with false alarms that were less than when the radiances of the nonfire pixels at 4 and 11 were estimated using past MODIS images with a standard deviation (SD) of 1 K. The analyses also indicated that, in order to obtain fewer errors than those obtained using the conventional contextual algorithm (MOD14) from the objective area (omission errors that are less than 62% and commission errors that are less than ), it is essential to carry out the nonfire radiance estimation using past images with an SD of less than 3 K. During an actual application of the multitemporal method to several fire cases, fewer errors occurred than those that occurred using MOD14.
Autors: Kushida, K.;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Apr 2010, volume: 7, issue:2, pages: 301 - 305
Publisher: IEEE
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» Detection of Gaussian constellations in MIMO systems under imperfect CSI
Abstract:
This paper considers the problem of Gaussian symbols detection in MIMO systems in the presence of channel estimation errors. Under this framework we develop a computationally efficient approximations of the MAP detector. The new detectors are based on a relaxation of the discrete nature of the digital constellation and on the channel estimation error statistics. This leads to a non-convex program that is solved efficiently via a hidden convexity minimization approach. Additionally, we show that using a Bayesian EM approach, comparable BER performance to that of the MAP detector can be achieved. Next we extend the detection scheme to the case where the noise variance is unknown. We present a modified Bayesian EM approach with annealed Gibbs sampling to perform joint noise variance estimation and symbols detection. Simulation results in a random MIMO system show that the proposed algorithm outperforms the linear MMSE receiver in terms of BER.
Autors: Nevat, I.;Peters, G.W.;Yuan, J.;
Appeared in: IEEE Transactions on Communications
Publication date: Apr 2010, volume: 58, issue:4, pages: 1151 - 1160
Publisher: IEEE
Full litterature document
 
» Detection of Human Microvibration Transmitted along Solid Using Pico-Tesla Magneto-Impedance Sensor
Abstract:
Human microvibration waveforms are sensitively detected using a newly developed pico-Tesla magneto-impedance sensor (pT-MI sensor) when the human skin is touched directly or indirectly via transmission solid by the sensor head. The origin of the microvibration is discussed, considering the cellular Ca2+ flow oscillation for the smooth muscle autonomous vibration. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Autors: Kaneo Mohri, Tsuyoshi Uchiyama
Appeared in: IEEJ Transactions on Electrical and Electronic Engineering
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Detection of non-stationary sinusoids by using joint frequency reassignment and null-to-null bandwidth
Abstract:
We present a method that efficiently describes non-stationarities by parameterizing spectral peaks in terms of the frequency reassignment operator variation and null-to-null peak bandwidth. This kind of parameterization is designed in such a way to properly deal with situations of low signal-to-noise ratios. In addition, it provides for a strong separation between the sinusoidal and noise peak class in a two-dimensional (2D) feature space. Consequently, the percentage of misclassified spectral peaks is drastically reduced, which significantly simplifies the analysis/synthesis of audio signals in the following processing stages.
Autors: Miroslav, Zivanovic
Appeared in: Digital Signal Processing
Publication date: Apr 2010
Publisher: Elsevier B.V.
Full litterature document
 
» Detection of the L-Band Galactic Glint on the Sea Surface With the Airborne MIRAS
Abstract:
This paper presents the results of the processing of the data acquired with the Airborne Microwave Imaging Radiometer with Aperture Synthesis, the European Space Agency's airborne 2-D aperture synthesis radiometer, in a circular flight over the sea in the vicinity of Helsinki (Finland). The goal of the analysis of these data is the detection of the galactic glint on the sea surface. These results are the first measurements with an L-band 2-D aperture synthesis radiometer that show the signature of the galaxy signal reflected on the sea surface.
Autors: Martin-Porqueras, F.;Floury, N.;Martin-Neira, M.;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Apr 2010, volume: 48, issue:4, pages: 1968 - 1975
Publisher: IEEE
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» Determining a Gas-Discharge Arrester Model's Parameters by Measurements and Optimization
Abstract:
This paper deals with the parameter determination procedure of a gas-discharge arrester's (GDA) model. As the accuracy of the model depends on its parameters, the goal of this procedure is to determine adequate parameter values so that the model's performances match the real device behavior as much as possible. In order to achieve this goal, differential evolution (DE), a stochastic optimization algorithm, is included in the determination process. The main task of the DE algorithm is to vary the model's parameters during the optimization process, thus minimizing the difference between the measured and model-calculated current and voltage time behavior. An accurate GDA model has been obtained on the basis of measurements on a single GDA test object. This model is relevant and suitable for a series of GDA devices as the agreement between their measured and model-calculated voltage and current time behavior is excellent.
Autors: Glotic, A.;Pihler, J.;Ribic, J.;Stumberger, G.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Apr 2010, volume: 25, issue:2, pages: 747 - 754
Publisher: IEEE
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» Determining the operative line of resection for image-guided emphysema surgery using a laser scanner and non-rigid registration
Abstract:
Although many diseases such as emphysema are diagnosed with preoperative imaging modalities, this information is rarely utilized in the operating room. A method that relates the preoperative images to the non-rigid organ in physical space would aid a surgeon to determine the line of resection.We used a three-dimensional (3D) laser scanner to obtain intraoperative images of the lung and overlayed it with preoperative CT images, using a non-rigid image registration method.The non-overlapping registration error of the system was 1.91 ± 0.28% without organ deformation and 2.69 ± 0.28% with 9% organ deformation. When 83% of the organ was visible, the registration error was 2.99 ± 0.42%.A novel image overlay system using a 3D laser scanner and a non-rigid registration method was implemented and its accuracy evaluated. By using the proposed system, we successfully related the preoperative images with an open organ in the operating room. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Jong-Ha Lee, Chang-Hee Won, Nathaniel Marchetti
Appeared in: The International Journal of Medical Robotics and Computer Assisted Surgery
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Determining the probability of flashover occurrence in composite insulators by using leakage current harmonic components
Abstract:
Flashover of contaminated insulators in polluted areas is one of the most important factors influencing the operation of transmission and distribution lines and substations. Hence predicting an approaching flashover is of a great importance. In this paper, a new method and criteria have been proposed to predict the flashover occurrence of SIR composite insulators and its probability by using leakage current harmonic component. The tests were performed on various profiles of artificially polluted SIR insulators under clean fog condition. It is proposed that an important index is the ratio of 5th harmonic component to the 3rd for which the operational and critical limits have been determined. The probability of flashover occurrence has also been calculated by geometric distribution. Only the measurements of a minimal set of parameters are required. The presented criteria can be used to optimally schedule overhead lines maintenance teams and to develop proper Condition-Based Monitoring Systems (CBMS). Experimental results illustrate high performance of this approach.
Autors: Kordkheili, H.H.;Abravesh, H.;Tabasi, M.;Dakhem, M.;Abravesh, M.M.;
Appeared in: IEEE Transactions on Dielectrics and Electrical Insulation
Publication date: Apr 2010, volume: 17, issue:2, pages: 502 - 512
Publisher: IEEE
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» Deterministic Flow Lines With Applications
Abstract:
We demonstrate that flow line models with deterministic service times and an arbitrary arrival process may be exactly decomposed into segments that each exhibit similar behavior. We call the segments channels and demonstrate that this decomposition leads to a recursion for the delay experienced by customers within the system. The consequence, in addition to clearly elucidating the manner in which customers advance, is that the state of a flow line at any time can be completely characterized by a handful of parameters per channel.
Autors: Morrison, J. R.;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Apr 2010, volume: 7, issue:2, pages: 228 - 239
Publisher: IEEE
Full litterature document
 
» Deterministic Robot-Network Localization is Hard
Abstract:
This paper provides a complexity study of the deterministic localization problem in robot networks using local and relative observations only. This is an important issue in collective and cooperative robotics where global positioning systems (GPS) are not available, and the basic premise is the localization ability of the group. We prove that given a set of relative observations made by the robots, the unique unambiguous pose estimation of the robot network in a deterministic way is an -hard problem. This means that no polynomial-time algorithm can deterministically solve the unique pose estimation problem based on relative observations unless . The consequence is that no guarantee can be provided, in a polynomial time, that the possibly estimated poses of the robots will correspond to the effective (actual) ones. The proof is based on complexity theory where we build appropriate polynomial-time reductions interrelating the multirobot localization problem to a well-known -complete problem (the partition problem). This -hardness result opens questions and perspectives for research into approximations to overcome its intractability.
Autors: Dieudonné, Y.;Labbani-Igbida, O.;Petit, F.;
Appeared in: IEEE Transactions on Robotics
Publication date: Apr 2010, volume: 26, issue:2, pages: 331 - 339
Publisher: IEEE
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» Developing a Stochastic Dynamic Programming Framework for Optical Tweezer-Based Automated Particle Transport Operations
Abstract:
Automated particle transport using optical tweezers requires the use of motion planning to move the particle while avoiding collisions with randomly moving obstacles. This paper describes a stochastic dynamic programming based motion planning framework developed by modifying the discrete version of an infinite-horizon partially observable Markov decision process algorithm. Sample trajectories generated by this algorithm are presented to highlight effectiveness in crowded scenes and flexibility. The algorithm is tested using silica beads in a holographic tweezer set-up and data obtained from the physical experiments are reported to validate various aspects of the planning simulation framework. This framework is then used to evaluate the performance of the algorithm under a variety of operating conditions.
Autors: Banerjee, A. G.;Pomerance, A.;Losert, W.;Gupta, S. K.;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Apr 2010, volume: 7, issue:2, pages: 218 - 227
Publisher: IEEE
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» Developing Electronic Health Records in Taiwan
Abstract:
The design of the Taiwan Electronic Medical Record Template (TMT) provides the basis for developing a document-based information standard and an information interoperability infrastructure for Taiwan's healthcare system. An additional benefit of TMT is its strong data security structure.
Autors: Rau, Hsiao-Hsien;Hsu, Chien-Yeh;Lee, Yen-Liang;Chen, Wei;Jian, Wen-Shan;
Appeared in: IT Professional
Publication date: Apr 2010, volume: 12, issue:2, pages: 17 - 25
Publisher: IEEE
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» Developing Mobile Business Processes for the Internet of Things
Abstract:
Mobile devices play a key role in reducing the gap between the physical and the digital world. The use of automatic identification capabilities can improve user participation in business processes where physical elements are involved (Smart Workflows). However, the solutions available today for connecting the physical world with the digital world lack the flexibility required to cope with the specific requirements of smart workflows. Each participant in a workflow has a different perspective on the physical elements of his/her surroundings. We provide a software architecture for the development of smart workflows that support different perspectives, labeling technologies and mobile platforms. Tool support is provided in order to automate the development process. An experiment was conducted to evaluate the suitability of the platform to support business processes in a labelled environment.
Autors: Giner, Pau;Cetina, Carlos;Fons, Joan;Pelechano, Vicente;
Appeared in: IEEE Pervasive Computing
Publication date: Apr 2010, volume: 9, issue:2, pages: 18 - 26
Publisher: IEEE
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» Developing RESTful Web Services with Webmachine
Abstract:
Many Web frameworks focus on projecting programming language entities out onto the Web, handling HTTP header parsing and the protocol itself but leaving it up to developers to make sure their classes and objects obey the rules of REST and HTTP RFC 2616. Webmachine is a unique Erlang framework that codifies HTTP's rules and decision flows, letting resource developers focus mostly on resource implementations and state representations. Webmachine also provides defaults for what it requires of resource implementations, enabling developers to implement only the specific framework callbacks required to realize their particular resources.
Autors: Sheehy, Justin;Vinoski, Steve;
Appeared in: IEEE Internet Computing
Publication date: Apr 2010, volume: 14, issue:2, pages: 89 - 92
Publisher: IEEE
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» Developing teamwork skills in capstone design courses [Senior Design]
Abstract:
The majority of our biomedical engineering graduates will eventually work in an industry where they will be part of multidisciplinary teams that use the collective skills, expertise, experience, and training of each team member. Diversity within these teams provides different perspectives, opinions, and ways of viewing problems, leading to a larger set of potential solutions. Successful careers require engineers to be able to function on multidisciplinary teams.
Autors: Goldberg, J.R.;
Appeared in: IEEE Engineering in Medicine and Biology Magazine
Publication date: Apr 2010, volume: 29, issue:2, pages: 141 - 142
Publisher: IEEE
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» Development of a Low-Cost FPGA-Based SSVEP BCI Multimedia Control System
Abstract:
This paper proposes a low-cost field-programmable gate-array (FPGA)-based brain–computer interface (BCI) multimedia control system, different from the BCI system, which uses bulky and expensive electroencephalography (EEG) measurement equipment, personal computer, and commercial real-time signal-processing software. The proposed system combines a customized stimulation panel, a brainwave-acquisition circuit, and an FPGA-based real-time signal processor and allows users to use their brainwave to communicate with or control multimedia devices by themselves. This study also designs a light-emitting diode stimulation panel instead of cathode ray tube or liquid-crystal display used in existing studies, to induce a stronger steady-state visual evoked potential (SSVEP), a kind of EEG, used as the input signal of the proposed BCI system. Implementing a prototype of the SSVEP-based BCI multimedia control system verifies the effectiveness of the proposed system. Experimental results show that the subjects' SSVEP can successfully control the multimedia device through the proposed BCI system with high identification accuracy.
Autors: Shyu, K.-K.;Lee, P.-L.;Lee, M.-H.;Lin, M.-H.;Lai, R.-J.;Chiu, Y.-J.;
Appeared in: IEEE Transactions on Biomedical Circuits and Systems
Publication date: Apr 2010, volume: 4, issue:2, pages: 125 - 132
Publisher: IEEE
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» Development of a low-noise IGBT module
Abstract:
High-frequency leakage current that may cause serious conducted EMI problems flows through an inverter system. The paths of the leakage current are stray capacitances that are formed inside of motors, cables, and IGBT modules. This paper proposes a new IGBT module that realizes low conducted emission noise by flipping the IGBT chip of the lower-voltage side to decrease its stray capacitance. The leakage current flowing through the low-noise IGBT module becomes small, since the stray capacitance is a main path of the current. Through an experiment, it is clarified that the conducted emission level is reduced by 13 dB at a maximum when the low-noise IGBT module is applied to a resonant-type inverter. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(4): 45-52, 2010; Published online in Wiley InterScience (). DOI 10.1002/eej.20971
Autors: Michio Tamate, Tamiko Sasaki, Akio Toba, Hiromu Takubo, Fernand Pasan, Kenji Okamoto
Appeared in: Electrical Engineering in Japan
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Development of a multipurpose vacuum chamber for serial optical and diffraction experiments with free electron laser radiation
Abstract:
In this paper we present a development of a multipurpose vacuum chamber which primal function is to be used in pump/probe experiments with free electron laser (FEL) radiation. The chamber is constructed for serial diffraction and serial spectroscopy allowing a fast exchange of samples during the measurement process. For the fast exchange of samples, liquid jet systems are used. Both applications, utilizing soft x-ray FEL pulses as pump and optical laser pulses as probe and vice versa are documented. Experiments with solid samples as well as the liquid jet samples are presented. When working with liquid jets, a system of automatically refilled liquid traps for capturing liquids has been developed in order to ensure stable vacuum conditions. Differential pumping stages are placed in between the FEL beamline and the experimental chamber so that working pressure in the chamber can be up to four orders of magnitude higher than the pressure in the FEL beamline.
Autors: Rajkovic, I.;Hallmann, J.;Grubel, S.;More, R.;Quevedo, W.;Petri, M.;Techert, S.;
Appeared in: Review of Scientific Instruments
Publication date: Apr 2010, volume: 81, issue:4, pages: 045105 - 045105-6
Publisher: IEEE
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» Development of a scanning angle total internal reflection Raman spectrometer
Abstract:
A scanning angle total internal reflection (SATIR) Raman spectrometer has been developed for measuring interfacial phenomena with chemical specificity and high axial resolution perpendicular to the interface. The instrument platform is an inverted optical microscope with added automated variable angle optics to control the angle of an incident laser on a prism/sample interface. These optics include two motorized translation stages, the first containing a focusing lens and the second a variable angle galvanometer mirror. The movement of all instrument components is coordinated to ensure that the same sample location and area are probed at each angle. At angles greater than the critical angle, an evanescent wave capable of producing Raman scatter is generated in the sample. The Raman scatter is collected by a microscope objective and directed to a dispersive spectrometer and charge-coupled device detector. In addition to the collected Raman scatter, light reflected from the prism/sample interface is collected to provide calibration parameters that enable modeling the distance over which the Raman scatter is collected for depth profiling measurements. The developed instrument has an incident angle range of 25.5°–75.5°, with a 0.05° angle resolution. Raman scatter can be collected from a ZnSe/organic interface over a range of roughly 35–180 nm. Far from the critical angle, the achieved axial resolution perpendicular to the focal plane is approximately 34 nm. This is roughly a 30-fold improvement relative to confocal Raman microscopy.
Autors: McKee, Kristopher J.;Smith, Emily A.;
Appeared in: Review of Scientific Instruments
Publication date: Apr 2010, volume: 81, issue:4, pages: 043106 - 043106-6
Publisher: IEEE
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» Development of a wide bandwidth Wilkinson power divider on multilayer organic substrates
Abstract:
We present the development of a miniaturized broadband Wilkinson power divider on a multilayer organic substrate with integrated thin film resistors. The VSWR for all port for both dividers is better than 1.6:1, the excess insertion loss is less than 1.6 dB up to 18 GHz, and 12 dB of isolation is realized. A size reduction of 43% is achieved. The proposed divider has the widest bandwidth ratio, 9:1, and the most compact size, 9.3 mm by 6 mm. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1606-1609, 2010; DOI 10.1002/mop.25252
Autors: Jia-Chi Samuel Chieh, Anh-Vu Pham
Appeared in: Microwave and Optical Technology Letters
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Development of absolute hot-wire anemometry by the method
Abstract:
We have developed hot-wire anemometry applying the method. The approach is based on the same heat transfer process as traditional anemometry, but substituting the constant current by a sinusoidal current and using synchronous detection to measure the conductive-convective exchange coefficient and the gas flow rate. Our theoretical model is tested with air flow at 300 K under atmospheric pressure: The experimental results are in agreement with the numerical simulation, justifying the technical choices in the method and the approximations made. The effectiveness of the method for measuring the flow rate and the conductive-convective exchange coefficient between the hot wire and flowing gas is discussed.
Autors: Heyd, Rodolphe;Hadaoui, Abdallah;Fliyou, Mohamed;Koumina, Abdelaziz;Ameziane, Lahcen El Hassani;Outzourhit, Abdelkader;Saboungi, Marie-Louise;
Appeared in: Review of Scientific Instruments
Publication date: Apr 2010, volume: 81, issue:4, pages: 044901 - 044901-6
Publisher: IEEE
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» Development of an evaluation method for controlling skill of a myoelectric control hand
Abstract:
The aim of this study was to develop a new evaluation method for controlling skill of a myoelectric control hand (MCH). Four amputees who daily used the MCH participated in this study. Measurement of two signals which were needed to control motion of the MCH was made. The two signals were assigned as the average rectified electromyograms of the forearm extensors and flexors. The values of the signals increased depending on the muscle contraction level. Therapy for using the MCH was performed to improve the ability to produce separate contractions of two muscles. This ability was defined as the skill in controlling the motion of the MCH. The skill in each motion was evaluated by the regression coefficient, which was calculated by the least squares method. The regression coefficient was inversely proportional to the skill. A quantitative index of skill can be provided by the newly developed method, and should be useful in developing efficient therapy to improve the skill in controlling the MCH. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(5): 15-23, 2010; Published online in Wiley InterScience (). DOI 10.1002/ecj.10255
Autors: Yoshizaki Hara, Hiroyuki Matsubara, Yaeko Shibata, Futoshi Mizobe, Yoshihiro Fukazawa, Makiko Okamoto, Takaaki Chin, Kotaro Minato, Masaki Yoshida
Appeared in: Electronics and Communications in Japan
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Development of Closed-Loop Neural Interface Technology in a Rat Model: Combining Motor Cortex Operant Conditioning With Visual Cortex Microstimulation
Abstract:
Closed-loop neural interface technology that combines neural ensemble decoding with simultaneous electrical microstimulation feedback is hypothesized to improve deep brain stimulation techniques, neuromotor prosthetic applications, and epilepsy treatment. Here we describe our iterative results in a rat model of a sensory and motor neurophysiological feedback control system. Three rats were chronically implanted with microelectrode arrays in both the motor and visual cortices. The rats were subsequently trained over a period of weeks to modulate their motor cortex ensemble unit activity upon delivery of intra-cortical microstimulation (ICMS) of the visual cortex in order to receive a food reward. Rats were given continuous feedback via visual cortex ICMS during the response periods that was representative of the motor cortex ensemble dynamics. Analysis revealed that the feedback provided the animals with indicators of the behavioral trials. At the hardware level, this preparation provides a tractable test model for improving the technology of closed-loop neural devices.
Autors: Marzullo, T. C.;Lehmkuhle, M. J.;Gage, G. J.;Kipke, D. R.;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Apr 2010, volume: 18, issue:2, pages: 117 - 126
Publisher: IEEE
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» Development of high-speed polarizing imaging system for operation in high pulsed magnetic field
Abstract:
A high-speed polarizing microscope system combined with a 37 T pulse magnet has been developed. This system was applied to successfully visualize the field-induced collapse of charge-orbital ordering in a layered manganite La1/2Sr3/2MnO4. Quantitative analyses of the obtained polarizing microscope images provided clear evidence of this transition in contrast to rather moderate changes in magnetization and magnetoresistance. The ability of this system to carry out quantitative analysis was further tested through the observation of Faraday rotation in a Tb3Ga5O12 crystal. The Verdet constant determined from the polarizing images is in reasonable agreement with that in literature. Local intensity analyses of the images indicate that we can investigate magneto-optical signals within an accuracy of 0.85% in an area of 9.6×9.6 μm2.
Autors: Katakura, I.;Tokunaga, M.;Matsuo, A.;Kawaguchi, K.;Kindo, K.;Hitomi, M.;Akahoshi, D.;Kuwahara, H.;
Appeared in: Review of Scientific Instruments
Publication date: Apr 2010, volume: 81, issue:4, pages: 043701 - 043701-5
Publisher: IEEE
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» Diagnosis of EHV and HV Transformers Through an Innovative Partial-Discharge-Based Technique
Abstract:
Online partial discharge (PD) analysis of power transformers is sometimes complex due to the presence of large disturbance and noise as well as to uncertainty in PD source identification. In this paper, a novel approach to PD detection and analysis in online power transformers is presented. The proposed approach provides hardware and software tools to remove disturbance, noise, separate contributions from different sources and, eventually, identify PD sources. Besides, a description of the hardware tools used to assemble the diagnostic system, the tests (in the lab and on real transformers) carried out to build the reference database needed for identification system training will be discussed, providing rules for PD source identification. A number of working cases will be presented to show the effectiveness of the proposed method.
Autors: Cavallini, A.;Chen, X.;Montanari, G. C.;Ciani, F.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Apr 2010, volume: 25, issue:2, pages: 814 - 824
Publisher: IEEE
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» DIANA.SC -- a versatile top-down analysis tool for switched-capacitor circuits
Abstract:
In this paper a general and designer-oriented top-down switched capacitor analysis tool, DIANA.SC is presented. The top-down feature of DIANA.SC allows for the analysis at a top level with ideal SC-circuits, at an intermediate level with SC-circuits containing resistors and op-amp poles and at a low level containing MOS-transistors and non-linear capacitors. The basic features and analysis modes at each of the levels are explained and illustrated. Several practical examples indicate the analysis levels and operation modes.
Autors: L., Claesen , H., de Man , J., Vandewalle , J., Rabaey
Appeared in: Microelectronics Journal
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Dielectric Behavior of Poly(3-Hexylthiophene)/Carbon Nanotube Composites by Broadband Dielectric Spectroscopy
Abstract:
Some of the most exciting novel approaches for renewable solar energy conversion are organic photovoltaic devices that take advantage of the unique properties of polymers such as poly(3-hexylthiophene) (P3HT). Although these types of devices present significant advantages (stability and price), their long-term performance has to be continuously improved. This paper describes the dielectric behavior of pristine P3HT and its nanocomposites versus temperature and frequency by using broadband dielectric spectroscopy. Dielectric spectra reveal the existence of two relaxation phenomena , below and above the glass transition. The relaxation is related to the crystallization phenomena, and the relaxation is due to dipolar polarization processes. These results can be incorporated into a continuous understanding of the electrical behaviors of such polymers, which play extremely important roles in the overall quality of photovoltaic devices that use such polymeric materials.
Autors: Petre, A.;Diaham, S.;Reyes-Melo, E.;Saini, V.;Li, Z.;Dervishi, E.;Xu, Y.;Biris, A. S.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Apr 2010, volume: 46, issue:2, pages: 627 - 633
Publisher: IEEE
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» Dielectric relaxation and polaronic conduction in double perovskite La2MgMnO6
Abstract:
The dielectric and conductive characteristics of double perovskite La2MgMnO6 were investigated together with the mixed-valence structure. The magnetic characterization and x-ray photoemission spectroscopy analysis showed the co-presence of Mn3+ and Mn4+. A Debye type dielectric relaxation with an activation energy of 0.33 eV was observed in La2MgMnO6 ceramics. The relaxorlike dielectric characteristic was attributed to the dipolar effects coming from charge carrier hopping between Mn3+ and Mn4+. The dc conductivity of La2MgMnO6 was well fitted using adiabatic small polaron theory, and also correlated with the mixed-valence structure of Mn3+/Mn4+.
Autors: Lin, Y. Q.;Chen, X. M.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:14, pages: 142902 - 142902-3
Publisher: IEEE
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» Dielectric tunability and electro-optic effect of Ba0.5Sr0.5TiO3 thin films
Abstract:
We elucidated the relationship between the dielectric tunability and the electro-optic (EO) effect. A new measurement system for EO effect and dielectric permittivity r) was developed to investigate the accurate correlation between EO and dielectric properties of epitaxial barium strontium titanate, Ba0.5Sr0.5TiO3 (BST) thin films grown on SrTiO3 (STO) substrates. The BST films had a strained lattice with a large lattice parameter along the thickness direction. Small birefringence was induced in the as-deposited film by the alignment of the c-axis in the film plane. The tunability of dielectric permittivity calculated from the complex voltage and current with planer electrodes reached to 53.1%, and the tunability of birefringence by EO effect was 0.6%. The birefringence change from EO effect was much lower than the tunability of dielectric permittivity. Therefore, there is no strong correlation between the dielectric tunability and EO effect, and the materials with high tunability do not always exhibit high EO effect. Finally, we discussed how to obtain the materials with high EO effect considering these results.
Autors: Takeda, K.;Muraishi, T.;Hoshina, T.;Takeda, H.;Tsurumi, T.;
Appeared in: Journal of Applied Physics
Publication date: Apr 2010, volume: 107, issue:7, pages: 074105 - 074105-5
Publisher: IEEE
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» Dielectrophoresis of Janus particles under high frequency ac-electric fields
Abstract:
Janus polystyrene particles with gold and dielectric multilayer coatings on one hemisphere are shown to drastically alter the dielectrophoresis (DEP) behavior of homogeneous precursor particles under ac-electric fields. Alkanethiol coatings on the gold-coated hemisphere can effectively modify the DEP crossover frequency c) with a negative (n) to positive (p) (p→n) DEP transition as increasing ac-frequency, in contrast to p→n DEP transition observed with precursor particles. All measured n→p DEP crossover frequencies with dependence on particle size, alkanethiol thickness, and medium conductivity are collapsed to yield a scaling with the resistance-capacitance (RC) time of the alkanethiol layer capacitance and the conductive medium resistance.
Autors: Zhang, Lu;Zhu, Yingxi;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:14, pages: 141902 - 141902-3
Publisher: IEEE
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» Differential space-time coded cooperation for decode-and-forward-based wireless relay networks
Abstract:
Estimating channel state information (CSI) in the fast fading conditions is very challenging. In this study, a simple structure for cooperative diversity in decode-and-forward mode is examined, in which the transmitter, the relay and the receiver do not know the CSI. In this scheme, transmission of information is done in a two-phase process. In the first phase, differential modulated signals are radiated from the source. After decoding the received signal in the relay, the source and the relay collectively send information using differential space- time codes. A closed-form optimum power allocation in the sense of minimising pairwise error probability (PEP) for high signal-to-noise ratio (SNR) scenarios has been obtained. An interesting property of the optimum point is that it is independent of the channel statistics and the position of the relay, which improves its feasibility in the future communication systems. Numerical simulations verify the analytical results.
Autors: Maham, B.;Hjorungnes, A.;
Appeared in: IET Communications
Publication date: Apr 2010, volume: 4, issue:6, pages: 631 - 638
Publisher: IEEE
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» Differentiated resilience services support in heterogeneous IP over wavelength division
Abstract:
The authors develop an integrated scheme that supports differentiated resilience services (DiffResServ) for dynamic provisioning in heterogeneous IP-over- wavelength division multiplexing (WDM) networks. By integrated, the authors mean that the provisioning mechanism takes into account network topology, resource and resilience information in both the IP and WDM layers. By dynamic, the authors mean that the establishment process of connections and lightpaths is based on the fact that the arrivals and departures of IP traffic connections are not known in advance. By heterogenous, the authors mean that the state routing algorithms function on the fact that optical nodes in WDM network may support different switching capabilities. This has been achieved through our proposed scheme which operates based on a dual link metrics (bandwidth,delay)routing algorithm inter-operating with efficient connections and lightpaths rerouting algorithms. A genetic algorithm is introduced to operate based on the solution space generated by this scheme in order to minimise the total cost of network operation. The authors have conducted simulations, where the results show that this scheme enables IP-over-WDM networks to guarantee the quality-of-service and resilience required for heterogenous traffic classes with effective and efficient allocation of network resources.
Autors: Alshaer, H.;Elmirghani, J.M.H.;
Appeared in: IET Communications
Publication date: Apr 2010, volume: 4, issue:6, pages: 645 - 662
Publisher: IEEE
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