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Electrical and Electronics Engineering publications abstract of: 01-2012 sorted by title, page: 16
» p-Type Films Deposited at Room Temperature for Thin-Film Transistors
Abstract:
Thin-films of copper oxide were sputtered from a metallic copper (Cu) target and studied as a function of oxygen partial pressure . A metallic Cu film with cubic structure obtained from 0% has been transformed to cubic phase for the increase in to 9% but then changed to monoclinic CuO phase (for ). The variation in crystallite size (calculated from x-ray diffraction data) was further substantiated by the variation in grain size (surface microstructures). The films produced with ranging between 9% and 75% showed p-type behavior, which were successfully applied to produce thin-film transistors.
Autors: Figueiredo, V.;Elangovan, E.;Barros, R.;Pinto, J. V.;Busani, T.;Martins, R.;Fortunato, E.;
Appeared in: Journal of Display Technology
Publication date: Jan 2012, volume: 8, issue:1, pages: 41 - 47
Publisher: IEEE
Full litterature document
 
» Packaged Triplexer Based on Distributed Coupling Technique
Abstract:
In one of the student design competitions at the IEEE MTT-S International Microwave Symposium 2011 (IMS2011) held at Baltimore, Maryland, the objective of the competition is to demonstrate the effective triplexer design techniques with the constraints of the metal package. The additional specifications are described as follows: insertion loss between CP and any in-band port less than 3.5 dB, insertion loss between CP and any port at frequencies 15% or more separated from the port's center frequency more than 20 dB, return loss for each in-band port better than 15 dB, return loss for CP at 3.35 GHz more than 15 dB, and isolation between output ports 2, 3, and 4 more than 20 dB. According to the requirements of the contest, two pieces of hardware are fabricated and measured. One is the unpackaged triplexer designed on printed circuit board (PCB) to validate the feasibility of design concepts. The packaged one has to maintain the first design's topology, but component values can be adjusted to compensate return loss and isolation after taking the package's effect into consideration. Both circuits must be connected with 50-Ω female subminiature version A (SMA) connectors, which are defined as reference planes while the triplexers are being measured.
Autors: Wu, J.-Y.;Tseng, Y.-H.;Tu, W.-H.;
Appeared in: IEEE Microwave Magazine
Publication date: Jan 2012, volume: 13, issue:1, pages: 139 - 145
Publisher: IEEE
Full litterature document
 
» Packet Video Error Concealment With Auto Regressive Model
Abstract:
In this paper, auto regressive (AR) model is applied to error concealment for block-based packet video coding. In the proposed error concealment scheme, the motion vector for each corrupted block is first derived by any kind of recovery algorithms. Then each pixel within the corrupted block is replenished as the weighted summation of pixels within a square centered at the pixel indicated by the derived motion vector in a regression manner. Two block-dependent AR coefficient derivation algorithms under spatial and temporal continuity constraints are proposed respectively. The first one derives the AR coefficients via minimizing the summation of the weighted square errors within all the available neighboring blocks under the spatial continuity constraint. The confidence weight of each pixel sample within the available neighboring blocks is inversely proportional to the distance between the sample and the corrupted block. The second one derives the AR coefficients by minimizing the summation of the weighted square errors within an extended block in the previous frame along the motion trajectory under the temporal continuity constraint. The confidence weight of each extended sample is inversely proportional to the distance toward the corresponding motion aligned block whereas the confidence weight of each sample within the motion aligned block is set to be one. The regression results generated by the two algorithms are then merged to form the ultimate restorations. Various experimental results demonstrate that the proposed error concealment strategy is able to improve both the objective and subjective quality of the replenished blocks compared to other methods.
Autors: Zhang, Y.;Xiang, X.;Zhao, D.;Ma, S.;Gao, W.;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jan 2012, volume: 22, issue:1, pages: 12 - 27
Publisher: IEEE
Full litterature document
 
» Packet-Hiding Methods for Preventing Selective Jamming Attacks
Abstract:
The open nature of the wireless medium leaves it vulnerable to intentional interference attacks, typically referred to as jamming. This intentional interference with wireless transmissions can be used as a launchpad for mounting Denial-of-Service attacks on wireless networks. Typically, jamming has been addressed under an external threat model. However, adversaries with internal knowledge of protocol specifications and network secrets can launch low-effort jamming attacks that are difficult to detect and counter. In this work, we address the problem of selective jamming attacks in wireless networks. In these attacks, the adversary is active only for a short period of time, selectively targeting messages of high importance. We illustrate the advantages of selective jamming in terms of network performance degradation and adversary effort by presenting two case studies; a selective attack on TCP and one on routing. We show that selective jamming attacks can be launched by performing real-time packet classification at the physical layer. To mitigate these attacks, we develop three schemes that prevent real-time packet classification by combining cryptographic primitives with physical-layer attributes. We analyze the security of our methods and evaluate their computational and communication overhead.
Autors: Proano, Alejandro;Lazos, Loukas;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jan 2012, volume: 9, issue:1, pages: 101 - 114
Publisher: IEEE
Full litterature document
 
» Palladium(II)-catalyzed oxidative homo-coupling of 1,3-dimethyluracil derivatives
Abstract:

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Autors: A palladium-catalyzed oxidative homo-coupling of 1,3-dimethyluracil was examined. Two types of uracil dimer, C5-C5? linked dimer and C5-C6? linked dimer were obtained in variable yields depending on the conditions along with a low yield of C5-C5? and
Appeared in: International Journal of Electrical Power & Energy Systems
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Palladium-catalyzed site-selective arylation of symmetric dichlorobenzaldehyde to non-symmetric diaryl benzaldehydeviaSuzuki coupling
Abstract:

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Autors: Arylation of 2,6-dichlorobenzaldehyde by aryl boronic acidsviasite-selective Suzuki coupling catalyzed by PdCl2supported on 4Å molecular sieves produces 2-aryl-6-chlorobenzaldehyde which on subsequent coupling with a different aryl boronic acid in pr
Appeared in: International Journal of Electrical Power & Energy Systems
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Pandemic Influenza Detection by Electrically Active Magnetic Nanoparticles and Surface Plasmon Resonance
Abstract:
Influenza A virus (FLUAV), the causative agent of influenza infection, has received extensive attention due to the recent swine-origin H1N1 pandemic. FLUAV has long been the cause of annual epidemics as well as less frequent but more severe global pandemics. Here, we describe a biosensor utilizing electrically active magnetic (EAM) polyaniline-coated nanoparticles as the transducer in an electrochemical biosensor for rapidly identifying FLUAV strains based on receptor specificity, which will be useful to monitor animal influenza infections and to characterize pandemic potential of strains that have transmitted from animals to humans. Pandemic potential requires human-to-human transmissibility, which is dependent upon FLUAV hemagglutinin (HA) specificity for host glycan receptors. Avian FLUAV preferentially bind to α2,3-linked receptors, while human FLUAV bind to α2,6-linked receptors. EAM nanoparticles were prepared by synthesizing aniline monomer around gamma iron (III) oxide (γ-Fe O ) cores, yielding 25–100-nm diameter nanoparticles that were structurally characterized by transmission electron microscopy and electron diffraction. The EAM nanoparticles were coated with monoclonal antibodies specific to H5N1 (A/Vietnam/1203/04). Specificity of binding between glycans and H5 was demonstrated. The biosensor results were correlative to supporting data from a surface plasmon resonance assay that characterized HA/glycan binding and α-H5 antibody activity. This novel study applies EAM nanoparticles as the transducer in a specific, portable, easy-to-use biosensor with great potential for disease monitoring and biosecurity applications.
Autors: Kamikawa, T. L.;Mikolajczyk, M. G.;Kennedy, M.;Zhong, L.;Zhang, P.;Setterington, E. B.;Scott, D. E.;Alocilja, E. C.;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Jan 2012, volume: 11, issue:1, pages: 88 - 96
Publisher: IEEE
Full litterature document
 
» Paper deacidification and UV protection using ZnO atomic layer deposition
Abstract:
Acid degradation of cellulosic paper in archival books, periodicals, and historic documents is a serious and widespread problem. Using acidic page samples from ∼40 year old books, we demonstrate that atomic layer deposition (ALD) ZnO can adjust and controllably neutralize the paper acid content. The paper samples were collected and analyzed in accordance with recognized Technical Association of the Pulp and Paper Industry (TAPPI) test standards. The average pH of the starting paper was 3.7 ± 0.4 and 4.4 ± 0.1 as determined using the TAPPI surface probe and cold water extraction methods, respectively. After 50 ALD ZnO cycles, the same tests on the coated paper produced an average pH of 7.39 ± 0.08 and 7.3 ± 0.4, respectively. Scanning electron microscopy confirmed that the cellulose structure remained intact during ALD. Additional tests of recently printed newspaper samples coated with ALD ZnO also show that ALD can effectively prevent paper discoloration and embrittlement caused by UV sunlight photoexposure. While there are many known methods for paper preservation, including others using diethyl zinc, the control afforded by ALD provides attractive advantages over other known approaches for preservation of archival paper and other natural fibrous materials.
Autors: Hanson, C. A.;Oldham, C. J.;Parsons, G. N.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2012, volume: 30, issue:1, pages: 01A117 - 01A117-5
Publisher: IEEE
Full litterature document
 
» Parameter Estimation Using Metaheuristics in Systems Biology: A Comprehensive Review
Abstract:
This paper gives a comprehensive review of the application of metaheuristics to optimization problems in systems biology, mainly focusing on the parameter estimation problem (also called the inverse problem or model calibration). It is intended for either the system biologist who wishes to learn more about the various optimization techniques available and/or the metaheuristic optimizer who is interested in applying such techniques to problems in systems biology. First, the parameter estimation problems emerging from different areas of systems biology are described from the point of view of machine learning. Brief descriptions of various metaheuristics developed for these problems follow, along with outlines of their advantages and disadvantages. Several important issues in applying metaheuristics to the systems biology modeling problem are addressed, including the reliability and identifiability of model parameters, optimal design of experiments, and so on. Finally, we highlight some possible future research directions in this field.
Autors: Sun, Jianyong;Garibaldi, Jonathan M.;Hodgman, Charlie;
Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics
Publication date: Jan 2012, volume: 9, issue:1, pages: 185 - 202
Publisher: IEEE
Full litterature document
 
» Parametric OBMC for Pixel-Adaptive Temporal Prediction on Irregular Motion Sampling Grids
Abstract:
This paper adapts overlapped block motion compensation (OBMC) to suit variable block-size motion partitioning. The motion vectors (MVs) for various partitions are formalized as motion samples taken on an irregular grid. From this viewpoint, determining OBMC weights to associate with these samples becomes an under-determined problem since a distinct solution has to be sought for each prediction pixel. In this paper, we tackle this problem by expressing the optimal weights in closed form based on parametric signal assumptions. In particular, the computation of this solution requires only the geometric relations between the prediction pixel and its nearby block centers, leading to a generic framework capable of reconstructing temporal predictors from any irregularly sampled MVs. A modified implementation is also proposed to address the MV location uncertainty and to reduce computational complexity. Experimental results demonstrate that our scheme performs better than similar previous works, and when compared to the recently proposed Quadtree-based adaptive loop filter and enhanced adaptive interpolation filter, show a comparable gain. Furthermore, the combination of it with either of them gives a combined effect that is almost the sum of their separate improvements.
Autors: Chen, Y.-W.;Peng, W.-H.;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jan 2012, volume: 22, issue:1, pages: 113 - 127
Publisher: IEEE
Full litterature document
 
» Partial relaying with layered encoding for efficient multi-hop transmission
Abstract:
Multi-hop transmission through wireless relays provides coverage extension and throughput enhancement. However, it may cause waste of bandwidth to meet half-duplex requirement of the relay. Motivated by this problem, we propose an efficient relaying scheme, referred to as partial relaying with layered encoding. In the proposed scheme, only partial information is transmitted via a relay, and a layered encoding is employed for the link between the source and relay for reliable delivery of the partial information. Simulation results confirm that the proposed scheme outperforms the conventional decode-and-forward relaying scheme, in terms of both the spectral efficiency and bit error rate.
Autors: Oh-Soon Shin
Appeared in: AEU - International Journal of Electronics and Communications
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Partially persistent B-trees with constant worst-case update time
Abstract:
image

Highlights

? We present partially persistent B-trees with O(1) worst-case update time. ? For adding partial persistence we use the fat-node and the node-copying method. ? The two resulting structures have different time complexities for searching a key. ? We only cover insertions and use standard techniques for incorporating deletions.

Autors:

Graphical abstract

Appeared in: Computers & Electrical Engineering
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Particle Filtering Based Estimation of Consistent Motion and Disparity With Reduced Search Points
Abstract:
A particle filtering based block-wise estimation method for estimation of motion in a video sequence and joint estimation of disparity and motion in a stereo video sequence is proposed. Parameters of motion and disparity of a block in a sequence are defined as a state, and evolution of the state with respect to the block index is tracked with particle filtering. The state is assumed to be dependent on the states of neighboring blocks. Estimated motion and disparity fields are consistent and suitable for intermediate frame or view generation. The particle filter provides a method to effectively sample the search space. The particles are concentrated in regions where the probability density function for the state has large values. Hence, the locations of the particles are good candidates for search points of a fast search method. The proposed method can estimate motion and disparity with a fraction of search points necessary for conventional estimation methods.
Autors: Yang, S.;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jan 2012, volume: 22, issue:1, pages: 91 - 104
Publisher: IEEE
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» Particle-size effects on the suppression of charge ordering in Nd0.8Na0.2MnO3
Abstract:
In this work, we have studied the suppression of the charge-ordered (CO) state in Nd0.8Na0.2MnO3 compound by varying the particle size and the applied magnetic field. The bulk samples with a particle size of D ≥ 140 nm exhibit different magnetic ground states, such as paramagnetic (PM), charge-ordering, ferromagnetic-cluster-glass (FM-CG), and reentrant-spin-glass-like (RSG) behavior. The complete suppression of charge ordering could be observed by reducing the particle size down to 50 nm. The field variation of magnetization curves at different temperatures show field-induced reversible transition from the antiferromagnetic (AFM) CO state to the FM state beyond a threshold field (HC). The M–H loops recorded at 5 K, show a distinct field-induced transition from a spin-frozen state to a FM state, especially on bulk samples with particle sizes of D ≥ 140 nm. T–H phase diagrams were constructed for samples with different particle sizes. The phase boundary between CO-AFM and FM states was found to shift toward higher temperature and lower magnetic fields with a decrease in particle size. Moreover, the phase-separation region was also found to narrow down with a decrease in particle size. The boundary of the spin-frozen state is found to shift toward lower temperature and magnetic field with decrease in particle size. The observed result could be explained based on the core-shell model.
Autors: Samantaray, B.;Srivastava, S. K.;Ravi, S.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:1, pages: 013919 - 013919-12
Publisher: IEEE
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» Passivity Enforcement for Admittance Models of Distributed Networks Using an Inverse Eigenvalue Method
Abstract:
Most transient circuit simulators are based on admittance representations of the constituent circuit elements. It is therefore natural to use admittance parameter descriptions of linear networks, preferably in the form of rational transfer functions that can be directly implemented in the analysis. A problem arises when the measured or calculated frequency-domain response of a linear distributed network must be derived from data that has inherent error, is of limited bandwidth, or is not in the appropriate rational form. A reduced-order rational model that is causal, stable, and passive must be developed. Previous methods of deriving rational functions for the admittance parameters of a network do guarantee stability and causality, but passivity of the model must be assured through subsequent post-processing. Enforcing passivity requires modification of the state-space parameters of the model with consequent introduction of errors. This paper reports on a procedure to simultaneously achieve passivity, accuracy, causality, and stability in the development of an admittance macromodel described using a matrix of rational functions. An iterative inverse eigenvalue algorithm enforces passivity, and is applied by conjoining sets of eigenvalue and admittance constraints. These constraints form a monolithic projection matrix, which simultaneously addresses both passivity and accuracy of the model.
Autors: Saunders, C. S.;Steer, M. B.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jan 2012, volume: 60, issue:1, pages: 8 - 20
Publisher: IEEE
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» Patterning of polystyrene thin films by solvent-assisted imprint lithography and controlled dewetting
Abstract:
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Autors: A self-organization process based on spinodal dewetting of a patterned thin PS film has been demonstrated
Appeared in: Microelectronic Engineering
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» pCloud: A Distributed System for Practical PIR
Abstract:
Computational Private Information Retrieval (cPIR) protocols allow a client to retrieve one bit from a database, without the server inferring any information about the queried bit. These protocols are too costly in practice because they invoke complex arithmetic operations for every bit of the database. In this paper, we present pCloud, a distributed system that constitutes the first attempt toward practical cPIR. Our approach assumes a disk-based architecture that retrieves one page with a single query. Using a striping technique, we distribute the database to a number of cooperative peers, and leverage their computational resources to process cPIR queries in parallel. We implemented pCloud on the PlanetLab network, and experimented extensively with several system parameters. Our results indicate that pCloud reduces considerably the query response time compared to the traditional client/server model, and has a very low communication overhead. Additionally, it scales well with an increasing number of peers, achieving a linear speedup.
Autors: Papadopoulos, Stavros;Bakiras, Spiridon;Papadias, Dimitris;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jan 2012, volume: 9, issue:1, pages: 115 - 127
Publisher: IEEE
Full litterature document
 
» Pentacene-based metal-insulator-semiconductor memory structures utilizing single walled carbon nanotubes as a nanofloating gate
Abstract:
A pentacene-based organic metal-insulator-semiconductor memory device, utilizing single walled carbon nanotubes (SWCNTs) for charge storage is reported. SWCNTs were embedded, between SU8 and polymethylmethacrylate to achieve an efficient encapsulation. The devices exhibit capacitance-voltage clockwise hysteresis with a 6 V memory window at ± 30 V sweep voltage, attributed to charging and discharging of SWCNTs. As the applied gate voltage exceeds the SU8 breakdown voltage, charge leakage is induced in SU8 to allow more charges to be stored in the SWCNT nodes. The devices exhibited high storage density (∼9.15 × 1011 cm-2) and demonstrated 94% charge retention due to the superior encapsulation.
Autors: Sleiman, A.;Rosamond, M. C.;Alba Martin, M.;Ayesh, A.;Al Ghaferi, A.;Gallant, A. J.;Mabrook, M. F.;Zeze, D. A.;
Appeared in: Applied Physics Letters
Publication date: Jan 2012, volume: 100, issue:2, pages: 023302 - 023302-4
Publisher: IEEE
Full litterature document
 
» Percolation model for the threshold voltage of field-effect transistors with nanocrystalline channels
Abstract:
We present a model for determining the threshold voltage of field-effect transistors with nanocrystalline active channel layers. In this type of device, the multiple boundaries between neighboring crystalline grains limit the charge-carrier transport. Electrons in the channel may either populate the conduction band within a grain or be trapped at an interface between neighboring grains. The relative distribution of the electrons over these states determines the conductances of the grains and of the boundaries between them. We employ simple carrier statistics to calculate the macroscopic densities of free and trapped carriers, and these densities are then used to define site and bond occupation probabilities for a two-dimensional site-bond percolation problem. The dependence of the threshold voltage on the primary model parameters: the energy of the trap states, the total density of traps, and the temperature, is explored.
Autors: Steinke, I. P.;Ruden, P. P.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:1, pages: 014510 - 014510-5
Publisher: IEEE
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» Perforation of aero-engine fan casing by a single rotating blade
Abstract:
To study the mechanism of the aero-engine fan blade/casing impact process, experiments on high-speed spin tester and numerical simulations employing a sufficiently fine mesh and suitable material relations were carried out. Numerical results were in good agreement with the experimental data. The fan casing was perforated under the impact of the blade which was released from the root. The whole impact process can be divided into three stages: the first stage is the released blade scratching the inner wall of the containment area; the second stage is bulge formation and cracking on the casing; and the third is the tearing of the casing along the ribs and the bending of the torn bands. The cracking of the bulge is induced by biaxial tension and the bulge formation is the main energy absorption mode of the casing. In addition, effects of stress initialization on numerical results are assessed according to the interaction force, strain and kinetic energies, and it is found that the stress initialization effects are negligible for this particular problem.
Autors: Qing He, Haijun Xuan, Lulu Liu, Weirong Hong, Rongren Wu
Appeared in: Aerospace Science and Technology
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Performance Analysis of an FLC-Based Online Adaptation of Both Hysteresis and PI Controllers for IPMSM Drive
Abstract:
This paper presents a closed-loop vector control of an interior permanent magnet synchronous motor (IPMSM) drive incorporating two separate fuzzy logic controllers (FLCs). The first one is a Mamdani-type FLC which minimizes the developed torque ripple by varying online the hysteresis band of the PWM current controller. The second one is an FLC-based tuned proportional-integral (PI) controller where the PI controller actually serves as the primary speed controller and its gains are tuned by a novel Sugeno-type FLC. Thus, the limitations of traditional PI controllers are avoided, and the performance of the drive system is improved. A flux controller is also incorporated in such a way that both torque and flux of the motor can be controlled while maintaining current and voltage constraints. Thus, the proposed drive extends the operating speed limits for the motor and enables the appropriate use of the reluctance torque. The proposed IPMSM drive is also implemented in real time using DSP board DS1104 for a laboratory 5 HP motor. A performance comparison of the proposed IPMSM drive with conventional PI controller-based drive is provided. Simulation and experimental results demonstrate the better dynamic response in torque and speed for the proposed drive over a wide speed range.
Autors: Rebeiro, R. S.;Uddin, M. N.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2012, volume: 48, issue:1, pages: 12 - 19
Publisher: IEEE
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» Performance Analysis of IEEE 802.11 WLANs With Saturated and Unsaturated Sources
Abstract:
This paper proposes a comprehensive but tractable model of IEEE 802.11 carrying traffic from a mixture of saturated and unsaturated (Poisson) sources, with potentially different quality-of-service (QoS) parameters, i.e., TXOP limit, , and . The model is used to investigate the interaction between these two types of sources, which is particularly useful for systems seeking to achieve load-independent “fair” service differentiation. We show that, when the TXOP limit for unsaturated sources is greater than one packet, batches are distributed as a geometric random variable clipped to TXOP limit. Furthermore, we present asymptotic results for access delay distribution, which indicates that it is infeasible to obtain real-time service in the presence of eight or more saturated sources, regardless of the real-time traffic load, given that all stations use a of 32.
Autors: Nguyen, S. H.;Vu, H. L.;Andrew, L. L. H.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2012, volume: 61, issue:1, pages: 333 - 345
Publisher: IEEE
Full litterature document
 
» Performance Analysis of PMIPv6-Based NEtwork MObility for Intelligent Transportation Systems
Abstract:
While host mobility support for individual mobile hosts (MHs) has been widely investigated and developed over the past years, there has been relatively less attention to NEtwork MObility (NEMO). Since NEMO Basic Support (NEMO-BS) was developed, it has been the central pillar in Intelligent Transport Systems (ITS) communication architectures for maintaining the vehicle's Internet connectivity. As the vehicle moves around, it attaches to a new access network and is required to register a new address obtained from the new access network to a home agent (HA). This location update of NEMO-BS often results in unacceptable long handover latency and increased traffic load to the vehicle. To address these issues, in this paper, we introduce new NEMO support protocols, which rely on mobility service provisioning entities introduced in Proxy Mobile IPv6 (PMIPv6), as possible mobility support protocols for ITS. As a base protocol, we present PMIPv6-based NEMO (P-NEMO) to maintain the vehicle's Internet connectivity while moving and without participating in the location update management. In P-NEMO, the mobility management for the vehicle is supported by mobility service provisioning entities residing in a given PMIPv6 domain. To further improve handover performance, fast P-NEMO (FP-NEMO) has been developed as an extension protocol. FP-NEMO utilizes wireless L2 events to anticipate the vehicle's handovers. The mobility service provisioning entities prepare the vehicle's handover prior to the attachment of the vehicle to the new access network. Detailed handover procedures for P-NEMO and FP-NEMO are provided, and handover timing diagrams are presented to evaluate the performance of the proposed protocols. P-NEMO and FP-NEMO are compared with NEMO-BS in terms of traffic cost and handover latency.
Autors: Lee, J.-H.;Ernst, T.;Chilamkurti, N.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2012, volume: 61, issue:1, pages: 74 - 85
Publisher: IEEE
Full litterature document
 
» Performance Analysis of Relay Assignment Schemes for Cooperative Networks with Multiple Source-Destination Pairs
Abstract:
In this paper, we consider two relay assignment schemes for cooperative networks comprising multiple source-destination pairs. Both schemes are based on the max-min criterion and aim at achieving the maximum spatial diversity for all pairs. One scheme is used as a performance benchmark since it considers all possible relay assignment permutations and selects the best one. The other scheme, on the other hand, considers only a subset of those permutations and selects the best one. The advantages of the latter one is that it reduces the complexity of the assignment process, in addition to making the performance analysis tractable. We examine these schemes over asymmetric channels using M-ary phase shift keying signaling. We consider both amplify-and-forward (AF) and decode-and-forward (DF) relaying where we derive expressions for the end-to-end (E2E) symbol error rate (SER). In both cases, we show that the full spatial diversity is achieved. To account for error propagation in DF relaying, we adopt a threshold-based relaying scheme whereby the relays forward only bits that are deemed reliable and remain silent otherwise. We compare this scheme to Genie-aided relaying where the relays forward only correctly decoded bits. We analyze these two schemes and derive expressions for the E2E SER performance. We present several numerical examples that validate the analytical results.
Autors: Zhang, Xuehua;Hasna, Mazen;Ghrayeb, Ali;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2012, volume: 11, issue:1, pages: 166 - 177
Publisher: IEEE
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» Performance Analysis of the Strong Uncorrelating Transformation in Blind Separation of Complex-Valued Sources
Abstract:
The strong uncorrelating transformation (SUT) is an effective tool for blind separation of complex-valued independent sources, commonly applied to the (spatial) sample autocovariance and pseudo-autocovariance matrices of the observed mixtures. In this work we analyze the performance (in terms of the resulting interference to source ratio (ISR)) of SUT-based blind separation of general wide-sense stationary complex-valued sources. Based on a small-errors analysis, we derive explicit expressions for the attainable ISR in terms of the temporal correlations and pseudo-correlations of the sources. We demonstrate by simulation that the empirical performance closely follows our analytic prediction at moderate to long observation lengths. An important implication ensuing from our analysis is that a rectilinear (“maximally improper”) source can be perfectly separated from all the other (nonrectilinear) sources.
Autors: Yeredor, A.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jan 2012, volume: 60, issue:1, pages: 478 - 483
Publisher: IEEE
Full litterature document
 
» Performance Enhancement of Silicon Nanowire Memory by Tunnel Oxynitride, Stacked Charge Trap Layer, and Mechanical Strain
Abstract:
Heavily doped silicon nanowires (SiNWs) are adopted to fabricate a memory device composed of an AlON tunnel layer and a charge trap bilayer, which exhibits a large memory window of 4.6 V when operated in the program/erase phases, i.e., 12 V for 100 and 12 V for 10 ms, along with excellent 70% extrapolated ten-year data retention and good endurance up to cycles. Strain effects on SiNW memory characteristics have also been investigated. It is demonstrated that the tensile strain increases the program window and the compressive strain improves the data retention. The underlying mechanism is attributed to the incorporation of nitrogen in the AlON tunnel layer.
Autors: Huang, C. J.;Yang, C. H.;Hsueh, C. Y.;Lee, J. H.;Chang, Y. T.;Lee, S. C.;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2012, volume: 33, issue:1, pages: 20 - 22
Publisher: IEEE
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» Performance Enhancement of Stand-Alone DFIG Systems With Control of Rotor and Load Side Converters Using Resonant Controllers
Abstract:
In this paper, the control of a stand-alone doubly fed induction generator (DFIG)-based wind power conversion system with unbalanced and nonlinear loads is investigated. Under these load conditions, the quality of stator voltage and current waveforms of the DFIG is strongly affected due to the negative and distorted components, reducing the performance of other normal loads connected to the DFIG. To tackle this problem, the control strategy is comprehensively developed in both rotor-side converter (RSC) and load-side converter (LSC) of the DFIG. The LSC is used as an active power filter to compensate for unbalanced and distorted stator currents whereas the RSC is developed to fully eliminate unbalanced and harmonic voltages at the point of common coupling. The proposed compensation method is based on current controllers in either the RSC or the LSC, which employ a proportional integral plus a resonant controller. These current controllers are controlled in the positive synchronous reference frame so that the rotor current and stator current are directly regulated without decomposing sequential components. Analytical issues on how to eliminate unbalanced and distorted components in the stator voltage and current are also described in this paper. To verify the effectiveness of the proposed control strategy, experimental results with 2.2-kW DFIG topology are presented and discussed in the paper.
Autors: Phan, V.-T.;Lee, H.-H.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2012, volume: 48, issue:1, pages: 199 - 210
Publisher: IEEE
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» Performance evaluation of preamble detectors for 3GPP-LTE physical random access channel
Abstract:
In this paper, the problem of preamble detection associated with random access procedure in 3GPP long term evolution (LTE) technology is tackled. Different detection strategies are proposed, both in time and frequency domain, in order to evaluate their performance in terms of missed detection probability (MDP) and hardware complexity. Results show that time-domain detectors are shown to be a valid alternative for preamble detection, since they fulfill the MDP requirements defined in 3GPP-LTE specification. Frequency-domain processing architectures achieve a better performance in terms of MDP, but at the expense of a greater complexity. Implementation requirements can be alleviated by reducing the number of quantization bits for the correlation operations, even up to 1-bit, while barely affecting the performance detection.
Autors: F. Javier López-Martínez, Eduardo del Castillo-Sánchez, Eduardo Martos-Naya, J. Tomás Entrambasaguas
Appeared in: Digital Signal Processing
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Performance Improvement by Stress Memorization Technique in Trigate Silicon Nanowire MOSFETs
Abstract:
We achieved significant on-current improvement in trigate silicon nanowire transistors by applying stress memorization technique (SMT). We found that the performance improvement by SMT in -oriented nanowire nFETs is caused by both the mobility improvement due to vertical compressive strain and the parasitic resistance reduction due to positive fixed charges at the gate edge induced by SMT process. Mobility increase ratio by SMT increases with reducing the nanowire width due to the enhanced strain. Although both the mobility and the parasitic resistance are degraded by SMT in pFETs, much larger performance improvement in nFETs leads to the improvement of total CMOS performance by SMT.
Autors: Saitoh, M.;Nakabayashi, Y.;Ota, K.;Uchida, K.;Numata, T.;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2012, volume: 33, issue:1, pages: 8 - 10
Publisher: IEEE
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» Performance Improvement of MDPSK Signal Reception in the Presence of Carrier Frequency Offset
Abstract:
Performance of mobile systems is significantly influenced by the carrier frequency offset caused by a Doppler shift, which leads to deployment of differential modulation schemes instead of coherent detection-based schemes. In this paper, we propose a novel -ary differential phase-shift keying (MDPSK) receiver that performs better than the receiver with MDPSK differential detection and is very close to the performance of a coherent MDPSK detector. The symbol error probability of the proposed MDPSK receiver is approximately constant within the practical frequency offset range. The proposed receiver may be used in the systems that work in fading and with high-frequency offset environments.
Autors: Dimitrijevic, B.;Nikolic, Z.;Milosevic, N.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2012, volume: 61, issue:1, pages: 381 - 385
Publisher: IEEE
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» Performance Improvement of One-Transistor DRAM by Band Engineering
Abstract:
We propose a novel one-transistor (1T) quantum well (QW) DRAM with raised GaP source/drain. This novel device structure shows much better retention time and sense margin than the existing silicon 1T DRAM (with and without QW). Detailed simulation study indicates that the proposed structure is scalable up to 15-nm gate length. The proposed device utilizes nearly lattice-matched heterostructures which have already been realized in the literature.
Autors: Pal, A.;Nainani, A.;Gupta, S.;Saraswat, K. C.;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2012, volume: 33, issue:1, pages: 29 - 31
Publisher: IEEE
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» Performance of a piezoelectric energy harvester driven by air flow
Abstract:
A turbulent wind source for possible energy harvesting is considered. To increase the amplitude of vibration, we apply a magnetopiezoelastic oscillator having a double well Duffing potential. The output voltage response of the system for different level of wind excitations is analyzed. The energy harvesting appeared to be the most efficient for the conditions close to the stochastic resonance region where the potential barrier was overcame.
Autors: Kitio Kwuimy, C. A.;Litak, G.;Borowiec, M.;Nataraj, C.;
Appeared in: Applied Physics Letters
Publication date: Jan 2012, volume: 100, issue:2, pages: 024103 - 024103-3
Publisher: IEEE
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» Performance of label switched path dynamic provisioning in GMPLS networks
Abstract:
Given the fact that control channels in GMPLS/MPLS-TE networks use packet-based forwarding, and the processing of control messages may be subject to various factors, the provisioning delay of an LSP could be highly random. To bridge the gap between the variable performance and demanding application needs, it is imperative to measure and characterize the LSP provisioning performance. In this article, we introduce the ongoing activities in IETF on defining standardized metrics and measurement methodologies for GMPLS/MPLS-TE performance. We also present our experiences in testing a number of GMPLS networks. The results can be seen as a sketch of performances of current state-of-the-art GMPLS implementations. We further point out possible future work in this area.
Autors: Sun, W.;Xing, Z.;Kang, K.;Jin, Y.;Guo, W.;Hu, W.;Zhang, G.;Papneja, R.;
Appeared in: IEEE Communications Magazine
Publication date: Jan 2012, volume: 50, issue:1, pages: 100 - 105
Publisher: IEEE
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» Performance of the 802.11p Physical Layer in Vehicle-to-Vehicle Environments
Abstract:
A reliable robust wireless network of connected vehicles is desired to enable a number of future telematics and infotainment applications in the vehicular domain. To achieve this objective, vehicle-to-vehicle (V2V) communication is standardized by the IEEE 802.11p Dedicated Short Range Communications (DSRC) standard. Providing reliable communication performance in a highly dynamic time-varying V2V channel is a challenging task. To tackle this challenge, we propose a dynamic equalization scheme, on top of the existing DSRC technology, that significantly improves the packet error rate (PER) of data transmissions without changing the DSRC standard. We also show a hardware implementation of this scheme based on a field-programmable gate array (FPGA) to demonstrate its implementation feasibility. Furthermore, we extend our improved equalization scheme to various data rate options available in the DSRC standard, showing that the proposed scheme is sufficiently generic to support different types of V2V communication. Finally, we report the results of investigating the dependence of wireless communication performance (in terms of PER and throughput) on various design parameters such as packet length, payload size, and data rate.
Autors: Fernandez, J. A.;Borries, K.;Cheng, L.;Vijaya Kumar, B. V. K.;Stancil, D. D.;Bai, F.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2012, volume: 61, issue:1, pages: 3 - 14
Publisher: IEEE
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» Periodicity-Enhanced Plasmon Resonances in the Scattering of Light by Sparse Finite Gratings of Circular Silver Nanowires
Abstract:
We consider the -polarized plane wave scattering by a finite linear grating of circular silver wires using the angular field expansions in local coordinates and addition theorems for cylindrical functions. The study is focused on the influence of the plasmon and the grating resonances on each other. It demonstrates that the scattering per one silver cylinder can be dramatically enhanced if the grating period is tuned to the plasmon-resonance wavelength value.Pub _bookmark Command="[Quick Mark]"
Autors: Natarov, D. M.;Sauleau, R.;Nosich, A. I.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2012, volume: 24, issue:1, pages: 43 - 45
Publisher: IEEE
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» Personalization of Cardiac Motion and Contractility From Images Using Variational Data Assimilation
Abstract:
Personalization is a key aspect of biophysical models in order to impact clinical practice. In this paper, we propose a personalization method of electromechanical models of the heart from cine-MR images based on the adjoint method. After estimation of electrophysiological parameters, the cardiac motion is estimated based on a proactive electromechanical model. Then cardiac contractilities on two or three regions are estimated by minimizing the discrepancy between measured and simulation motion. Evaluation of the method on three patients with infarcted or dilated myocardium is provided.
Autors: Delingette, H.;Billet, F.;Wong, K. C. L.;Sermesant, M.;Rhode, K.;Ginks, M.;Rinaldi, C. A.;Razavi, R.;Ayache, N.;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jan 2012, volume: 59, issue:1, pages: 20 - 24
Publisher: IEEE
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» Pervasive Tabs, Pads, and Boards: Are We There Yet?
Abstract:
How far have we come with respect to commercial deployments of the devices Mark Weiser described? This review of Weiser's vision evaluates the commercial success of tabs, pads, and boards and discusses their real-world use.
Autors: Ebling, Maria R.;Baker, Mary;
Appeared in: IEEE Pervasive Computing
Publication date: Jan 2012, volume: 11, issue:1, pages: 42 - 51
Publisher: IEEE
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» Phase Noise Analysis of the Tuned-Input–Tuned-Output (TITO) Oscillator
Abstract:
The theoretical phase noise performance of a tuned-input tuned-output (TITO) oscillator is analyzed with a rigorous approach, which yields a compact closed-form phase noise equation that is dependent only on the value of the circuit components and current consumption of the oscillator. A straightforward comparison with the more commonly used differential LC-tank oscillator shows that the latter is in fact superior to the TITO oscillator, at least if the oscillator behavior is not too distant from the ideal behavior considered in the analysis. Phase noise simulations match admirably the theoretical results.
Autors: Bevilacqua, A.;Andreani, P.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jan 2012, volume: 59, issue:1, pages: 20 - 24
Publisher: IEEE
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» Phase-controlled, heterodyne laser-induced transient grating measurements of thermal transport properties in opaque material
Abstract:
The methodology for a heterodyned laser-induced transient thermal grating technique for non-contact, non-destructive measurements of thermal transport in opaque material is presented. Phase-controlled heterodyne detection allows us to isolate pure phase or amplitude transient grating signal contributions by varying the relative phase between reference and probe beams. The phase grating signal includes components associated with both transient reflectivity and surface displacement whereas the amplitude grating contribution is governed by transient reflectivity alone. By analyzing the latter with the two-dimensional thermal diffusion model, we extract the in-plane thermal diffusivity of the sample. Measurements on a 5 μm thick single crystal PbTe film yielded excellent agreement with the model over a range of grating periods from 1.6 to 2.8 μm. The measured thermal diffusivity of 1.3 × 10-6 m2/s was found to be slightly lower than the bulk value.
Autors: Johnson, Jeremy A.;Maznev, Alexei A.;Bulsara, Mayank T.;Fitzgerald, Eugene A.;Harman, T. C.;Calawa, S.;Vineis, C. J.;Turner, G.;Nelson, Keith A.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:2, pages: 023503 - 023503-7
Publisher: IEEE
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» Phospholipid film in electrolyte-gated organic field-effect transistors
Abstract:
image

Highlights

? An electrolyte-gated OFET embedding a lipid film is proposed. ? The OFETs operate at low voltages in water and in electrolyte solutions. ? The P3HT doping is minimized achieving a capacitive operational mode. ? New perspectives to the biosensor development working in water.

Autors:

Graphical abstract

An electrolyte-gated OFET including a phospholipid film at the inte
Appeared in: Organic Electronics
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Phosphorescent nanoparticles for quantitative measurements of oxygen profilesin vitroandin vivo
Abstract:
We present the development and characterization of nanoparticles loaded with a custom phosphor; we exploit these nanoparticles to perform quantitative measurements of the concentration of oxygen within three-dimensional (3-D) tissue culturesin vitroand blood vesselsin vivo. We synthesized a customized ruthenium (Ru)-phosphor and incorporated it into polymeric nanoparticles via self-assembly. We demonstrate that the encapsulated phosphor is non-toxic with and without illumination. We evaluated two distinct modes of employing the phosphorescent nanoparticles for the measurement of concentrations of oxygen: 1)in vitro, in a 3-D microfluidic tumor model via ratiometric measurements of intensity with an oxygen-insensitive fluorophore as a reference, and 2)in vivo, in mouse vasculature using measurements of phosphorescence lifetime. With both methods, we demonstrated micrometer-scale resolution and absolute calibration to the dissolved oxygen concentration. Based on the ease and customizability of the synthesis of the nanoparticles and the flexibility of their application, these oxygen-sensing polymeric nanoparticles will find a natural home in a range of biological applications, benefiting studies of physiological as well as pathological processes in which oxygen availability and concentration play a critical role.
Autors: Nak Won Choi, Scott S. Verbridge, Rebecca M. Williams, Jin Chen, Ju-Young Kim, ...
Appeared in: Microelectronics Journal
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Photodegradation of phenol and benzoic acid by sol-gel-synthesized alkali metal-doped ZnO
Abstract:
The effect of three alkali metal dopants on the photocatalytic properties of zinc oxide (ZnO) was investigated. Crystallized powders of ZnO doped with 10% lithium, sodium and potassium synthesized by a sol-gel process with zinc acetate and oxalic acid precursors were characterized by X-ray diffraction, scanning electron microscopy, UV-Vis diffuse reflectance and nitrogen adsorption isotherms. Photocatalytic activity under ultraviolet irradiation of undoped and doped ZnO powders was tested by degradation of phenol and benzoic acid, chosen as model organic pollutants. Doping ZnO with lithium, sodium and potassium increases the crystallinity of powders and reduces band gap energy. Comparison of photocatalytic activity of undoped and doped ZnO powders demonstrates that doping with sodium and lithium increases the efficiency of degradation of both phenol and benzoic acid.
Autors: Hadj Benhebal, Messaoud Chaib, Angélique Leonard, Stéphanie D. Lambert, Michel Crine
Appeared in: Materials Science in Semiconductor Processing
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Photoluminescence and secondary ion mass spectrometry investigation of unintentional doping in epitaxial germanium thin films grown on III-V compound by metal-organic chemical vapor deposition
Abstract:
High quality epitaxial germanium (Ge) thin films grown on lattice matched and mismatched III-V compound may lead to development of new electronic and optoelectronic devices. Understanding the doping and electronic properties of these Ge thin films is the first step in this development. In this paper, we report on high-quality epitaxial Ge thin films grown on GaAs and AlAs by metal-organic chemical vapor deposition. Cross-sectional transmission electron microscopy and atomic force microscopy reveal the high structural quality of the Ge thin films. Using photoluminescence, secondary ion mass spectrometry, and spreading resistance analysis, we investigated the unintentional doping characteristics of the fabricated Ge-on-III-V thin films. We found that arsenic (n-type doping) concentration is determined by the background partial pressure of volatile As-species (e.g., As2 and As4), which incorporate into the Ge thin films via gas phase transport during the growth. Group III element (p-type doping) incorporation in the Ge thin films occurs during the growth through a surface exchange process. There exists a trade-off between Ge film structural quality and group III element “auto-doping.” III-V compound surfaces that are group III element-rich facilitate the initiation of Ge thin films with high crystalline quality and low surface roughness. However, the group-III-rich surfaces also result in high group III element (p-type doping) concentrations in the Ge thin films.
Autors: Bai, Yu;Bulsara, Mayank T.;Fitzgerald, Eugene A.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:1, pages: 013502 - 013502-8
Publisher: IEEE
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» Photoluminescence decay of direct and indirect transitions in Ge/SiGe multiple quantum wells
Abstract:
We present a detailed experimental study of the photoluminescence decay of direct Γ-Γ and indirect L-Γ transitions in compressively strained Ge/Si0.15Ge0.85 type I multiple quantum wells. The lifetime of the fundamental L-Γ indirect-gap related transition is in the 6 to 13 ns range at the lattice temperature of 14 K. These values are just one order of magnitude higher than those typical of type-I direct gap III-V quantum wells and are significantly shorter than those characteristic of type-II indirect gap SiGe/Si quantum wells. The measured decay times show a clear dependence on the quantum well width and lattice temperature. The decay of the Γ-Γ direct-gap related transition is dominated by the ultrafast electron scattering from Γ-type to L-type states of the conduction band.
Autors: Giorgioni, A.;Gatti, E.;Grilli, E.;Chernikov, A.;Chatterjee, S.;Chrastina, D.;Isella, G.;Guzzi, M.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:1, pages: 013501 - 013501-4
Publisher: IEEE
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» Photonic Ultra-Wideband Transmitter Using a Chirped Heterodyne Technique
Abstract:
A photonic ultra-wideband (UWB) impulse transmitter based on chirped heterodyning is demonstrated. It uses no high-speed electronics or optical modulators. Multiple data formats including high-order pulse-position modulation are implementable, as is switching among data formats. The transmitter is robust against fiber-propagation distortions and is capable of optimally filling the Federal Communications Commission, or any other, UWB spectral mask.
Autors: Sefler, G. A.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2012, volume: 24, issue:2, pages: 128 - 130
Publisher: IEEE
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» Photovoltaic quantum dot quantum cascade infrared photodetector
Abstract:
Design and characterization of a quantum dot quantum cascade detector for photovoltaic midwave infrared photodetection (λpeak = 5.5 μm) is demonstrated. The quantum cascade barrier region provides the internal electric field to transfer photoexcited electrons into quantum dots of the next stack, enabling zero bias operation. Increased carrier relaxation time for intersubband transitions in quantum dots provides a distinct advantage for the carrier transport. Responsivity of 10 mA/W and detectivity of 9 × 109 cm Hz1/2 W-1 at 77 K for f/2 optics has been obtained at zero bias. Dark current density is 6.5 × 10-7A cm-2, at 80 K at zero bias.
Autors: Barve, A. V.;Krishna, S.;
Appeared in: Applied Physics Letters
Publication date: Jan 2012, volume: 100, issue:2, pages: 021105 - 021105-3
Publisher: IEEE
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» Physical and Electrical Analysis of Post- Fluorine Plasma Treatment for the Improvement of MOSFETs' Performance
Abstract:
Notable improvements in the gate stack have been achieved by a post- fluorine plasma treatment, including excellent interface quality of low equivalent oxide thickness (1.4 nm) directly on without using an interface passivation layer, reduction in interface trap density from to , reduced border traps from to , and 40% less charge-trapping centers. As a result, improved electrical performances have been obtained. Frequency dispersion in capacitance–voltage characteristics has been reduced. Subthreshold swing has been improved from 127 to 109 mV/dec. Effective channel mobility has been enhanced from 826 to 1067 . An improved drive current of 123 mA/mm at and $V_{g} - V_{rm th} = hbox{2} hbox{V}$ (5- channel length) has been also presented.
Autors: Chen, Y.-T.;Wang, Y.;Xue, F.;Zhou, F.;Lee, J. C.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2012, volume: 59, issue:1, pages: 139 - 144
Publisher: IEEE
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» Physical Parameter-Based SPICE Models for InGaZnO Thin-Film Transistors Applicable to Process Optimization and Robust Circuit Design
Abstract:
In this letter, we show that the physics-based equation that was derived for amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) in our previous work can be successfully incorporated into the SPICE model via Verilog-A. The proposed model and extracted SPICE parameters successfully reproduce the measured current–voltage characteristics of amorphous indium–gallium–zinc-oxide (a-IGZO) TFTs and the load line diagram of a-IGZO TFT inverters. The main advantage of our model is that each parameter has its physical meaning and most of them can be related with the fabrication conditions of AOS TFTs. To show the advantage of the proposed models and extracted SPICE parameters more clearly, we investigate the effect of ionized donor concentration on the inverter circuit operation and determine the optimum value of and device dimensions considering the tradeoff between the power consumption and the output swing in a-IGZO inverters. The proposed physics-based SPICE model via Verilog-A is expected to play a significant role in the process optimization and circuit design with AOS TFTs.
Autors: Kim, D. H.;Jeon, Y. W.;Kim, S.;Kim, Y.;Yu, Y. S.;Kim, D. M.;Kwon, H.-I.;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2012, volume: 33, issue:1, pages: 59 - 61
Publisher: IEEE
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» PID-State Torque Control in Electromechanical Drive Systems Under Stochastic Load
Abstract:
Many technical processes with stochastic workflow are characterized by high load peaks. Those load peaks propagate in the power train of the electromechanical drive system to the feeding power grid and at the same time stimulate torsion oscillations. For smoothing the load peaks as well as damping the torque oscillations, a novel torque control was designed. The concept consists of a PID-state control and was compared to standard control methods such as standard PID control. The PID-state control shows distinctive advantages with respect to the reference-variable response and the manipulated variable requirement.
Autors: Sourkounis, C.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2012, volume: 48, issue:1, pages: 20 - 27
Publisher: IEEE
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» Piezoresistive silicon nanowire based nanoelectromechanical system cantilever air flow sensor
Abstract:
We present nanoelectromechanical system based cantilever air flow sensor using silicon nanowires (SiNWs). The cantilever is fabricated in the complementary metal-oxide-semiconductor compatible process with dimension of 90 μm × 20 μm × 3 μm. SiNWs with the size of 2 μm × 90 nm × 90 nm (length × width × height) are embedded at the edge of the cantilever fixed end to experience the maximum air flow induced strain. Compared with recently reported air flow sensors, our device shows a better sensitivity of 198 Ω/m/s and a flow sensing range up to 65 m/s. In addition, improvements in terms of linearity, hysteresis, and lower power consumption are reported as well.
Autors: Zhang, Songsong;Lou, Liang;Lee, Chengkuo;
Appeared in: Applied Physics Letters
Publication date: Jan 2012, volume: 100, issue:2, pages: 023111 - 023111-3
Publisher: IEEE
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» Pig slurry treatment by a hybrid multi-stage unit system consisting of an ATAD and an EGSB followed by a SBR reactor
Abstract:

Highlights

? The feasibility of an innovative HMUS system was evaluated. ? Pig slurry treatment by multi-stage process was tested. ? ATAD and EGSB followed by SBR process were used. ? Both VS and COD in the feed pig slurry were reduced by about 98.9%.


Autors: Experiments in a laboratory-scale hybrid multi-stage unit system (HMUS) for pig slurry treatment were conducted to demonstrate the feasibility of using autothermal thermophilic aerobic digestion (ATAD), coagulation and expanded granular sludge bed (E
Appeared in: Biosystems Engineering
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Pilot-Symbol Assisted Power Delay Profile Estimation for MIMO-OFDM Systems
Abstract:
This letter proposes a power delay profile (PDP) estimation technique for linear minimum mean square error (LMMSE) channel estimator of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. For practical applications, only the pilot symbols of all transmit antenna ports are used in estimating the PDP. The distortions caused by null subcarriers and an insufficient number of samples for PDP estimation are also considered. The proposed technique effectively reduces the distortions for accurate PDP estimation. Simulation results show that the performance of LMMSE channel estimation using the proposed PDP estimate approaches that of Wiener filtering due to the mitigation of distortion effects.
Autors: Kim, Young-Jin;Im, Gi-Hong;
Appeared in: IEEE Communications Letters
Publication date: Jan 2012, volume: 16, issue:1, pages: 68 - 71
Publisher: IEEE
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» Planning and obstacle avoidance in mobile robotics
Abstract:

Highlights

? The article introduce Roaming Trails to integrate planning and obstacle avoidance. ? Roaming Trails define the maximum distance for the robot to deviate from its path. ? Roaming Trails guarantee that the robot can never be trapped in a deadlock. ? The article includes theoretical analyses and experiments.


Autors: The paper focuses on the navigation subsystem of a mobile robot which operates in human environments to carry out different tasks, such as transporting waste in hospitals or escorting people in exhibitions. The paper describes a hybrid approach (Roam
Appeared in: Robotics and Autonomous Systems
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Plasma and vacuum ultraviolet induced charging of SiO2 and HfO2 patterned structures
Abstract:
The authors compare the effects of plasma charging and vacuum ultraviolet (VUV) irradiation on oxidized patterned Si structures with and without atomic-layer-deposited HfO2. It was found that, unlike planar oxidized Si wafers, oxidized patterned Si wafers charge up significantly after exposure in an electron-cyclotron resonance plasma. The charging is dependent on the aspect ratio of the patterned structures. This is attributed to electron and/or ion shading during plasma exposure. The addition of a 10 nm thick HfO2 layer deposited on top of the oxidized silicon structures increases the photoemission yield during VUV irradiation, resulting in more trapped positive charge compared to patterns without the HfO2 dielectric.
Autors: Lauer, J. L.;Upadhyaya, G. S.;Sinha, H.;Kruger, J. B.;Nishi, Y.;Shohet, J. L.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2012, volume: 30, issue:1, pages: 01A109 - 01A109-6
Publisher: IEEE
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» Plasma enhanced atomic layer batch processing of aluminum doped titanium dioxide
Abstract:
Among many promising high-k dielectrics, TiO2 is an interesting candidate because of its relatively high k value of over 40 and its easy integration into existing semiconductor manufacturing schemes. The most critical issues of TiO2 are its low electrical stability and its high leakage current density. However, doping TiO2 with Al has shown to yield significant improvement of layer quality on Ru electrodes [S. K. Kim etal, Adv. Mater. 20, 1429 (2008)]. In this work we investigated if atomic layer deposition (ALD) of Al doped TiO2 is feasible in a batch system. Electrical characterizations were done using common electrode materials like TiN, TaN, or W. Additionally, the effect of plasma enhanced processing in this reactor was studied. For this investigation a production batch ALD furnace has been retrofitted with a plasma source which can be used for post deposition anneals with oxygen radicals as well as for directly plasma enhanced ALD. After evaluation of several Ti precursors a deposition process for AlTiOx with excellent film thickness and composition uniformity was developed. The effects of post deposition anneals, Al2O3 interlayers between electrode and TiO2, Al doping concentration, plasma enhanced deposition and electrode material type on leakage current density are shown. An optimized AlTiOx deposition process on TaN electrodes yields to leakage current density of 5 × 10-7 A/cm2 at 2 V and k values of about 35. Thus, it could be demonstrated that a plasma enhanced batch ALD process for Al doped TiO2 is feasible with acceptable leakage current density on a standard electrode material.
Autors: Lehnert, Wolfgang;Ruhl, Guenther;Gschwandtner, Alexander;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2012, volume: 30, issue:1, pages: 01A152 - 01A152-6
Publisher: IEEE
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» Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas
Abstract:
The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 °C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF6 and O2 under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film’s removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film removal because the film was inert to the SFx+ and O+ chemistries. The etch experiments showed the film to be a resilient masking material. This makes it an attractive candidate for use as an etch mask in demanding SF6 based plasma etch applications, such as through-wafer etching, or when oxide films are not suitable.
Autors: Perros, Alexander;Bosund, Markus;Sajavaara, Timo;Laitinen, Mikko;Sainiemi, Lauri;Huhtio, Teppo;Lipsanen, Harri;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2012, volume: 30, issue:1, pages: 011504 - 011504-5
Publisher: IEEE
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» Plasma-enhanced atomic layer deposition and etching of high-k gadolinium oxide
Abstract:
Atomic layer deposition (ALD) of high-quality gadolinium oxide thin films is achieved using Gd(iPrCp)3 and O2 plasma. Gd2O3 growth is observed from 150 to 350 °C, though the optical properties of the film improve at higher temperature. True layer-by-layer ALD growth of Gd2O3 occurred in a relatively narrow window of temperature and precursor dose. A saturated growth rate of 1.4 Å/cycle was observed at 250 °C. As the temperature increases, high-quality films are deposited, but the growth mechanism appears to become CVD-like, indicating the onset of precursor decomposition. At 250 °C, the refractive index of the film is stable at ∼1.80 regardless of other deposition conditions, and the measured dispersion characteristics are comparable to those of bulk Gd2O3. XPS data show that the O/Gd ratio is oxygen deficient at 1.3, and that it is also very hygroscopic. The plasma etching rate of the ALD Gd2O3 film in a high-density helicon reactor is very low. Little difference is observed in etching rate between Cl2 and pure Ar plasmas, suggesting that physical sputtering dominates the etching. A threshold bias power exists below which etching does not occur; thus it may be possible to etch a metal gate material and stop easily on the Gd2O3 gate dielectric. The Gd2O3 film has a dielectric constant of about 16, exhibits low C–V hysteresis, and allows a 50 × reduction in gate leakage compared to SiO2. However, the plasma enhanced atomic layer deposition (PE-ALD) process causes formation of an ∼1.8 nm SiO2 interfacial layer, and generates a fixed charge of -1.21 × 1012 cm-2, both of which may limit use of PE-ALD Gd2O3 as a gate dielectric.
Autors: Vitale, Steven A.;Wyatt, Peter W.;Hodson, Chris J.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2012, volume: 30, issue:1, pages: 01A130 - 01A130-7
Publisher: IEEE
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» Plasmon-enhanced upconversion fluorescence in NaYF4:Yb/Er/Gd nanorods coated with Au nanoparticles or nanoshells
Abstract:
We investigate plasmon-enhanced upconversion (UC) fluorescence in Yb3+-Er3+-Gd+3 codoped sodium yttrium fluoride (NaYF4:Yb/Er/Gd) nanorods using gold nanoparticles or nanoshells. A simple method was proposed for the preparation of core/shell NaYF4/Au structures, with dispersed Au nanoparticles or uniform Au coating on the surface of the UC nanorod. Pure hexagonal-phase NaYF4:Yb/Er/Gd nanorods were synthesized via a liquid-solid reaction in oleic acid and ethanol solvent. A one-step approach was introduced to modify the hydrophobic surfaces of the as-deposited NaYF4:Yb/Er/Gd nanorods. After this surface modification, Au nanoparticles or nanoshells were successfully attached on the surfaces of NaYF4:Yb/Er/Gd nanorods. The as-deposited UC nanorods showed a strong UC emission in green and red bands under 980 nm laser excitation. The attachment of Au nanoparticles onto NaYF4:Yb/Er/Gd nanorods resulted in a more than three-fold increase in UC emissions, whereas the formation of continuous and compact Au shells around the nanorods suppressed the emissions. The related interaction mechanisms of the UC emission of NaYF4:Yb/Er/Gd nanorods with plasmon modes in Au nanostructures are analyzed and discussed.
Autors: Li, Z. Q.;Chen, S.;Li, J. J.;Liu, Q. Q.;Sun, Z.;Wang, Z. B.;Huang, S. M.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:1, pages: 014310 - 014310-7
Publisher: IEEE
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» Platform Skin Return and Retrodirective Cross-Eye Jamming
Abstract:
The effect of platform skin return on retrodirective cross-eye jamming is analysed, allowing the parameters of a cross-eye jammer in the presence of skin return to be determined. The inherently unknown phase of the platform skin return is accounted for, and the effect of variations in jammer-to-signal ratio (JSR) is investigated. The widely-held, though unsubstantiated, view that a JSR of 20 dB is required for effective cross-eye jamming is found to be reasonable, though conservative.
Autors: Du Plessis, W. P.;
Appeared in: IEEE Transactions on Aerospace and Electronic Systems
Publication date: Jan 2012, volume: 48, issue:1, pages: 490 - 501
Publisher: IEEE
Full litterature document
 
» PLL charge pump with adaptive body-bias compensation for minimum current variation
Abstract:
A novel charge pump with adaptive body-bias compensation to minimise the current variation over a wide output voltage range is proposed. With 1.2 V supply voltage, the proposed charge pump demonstrates a constant current of 140 μA across the output voltage from 0.2 to 1.0 V. The current variation is less than 1.20 μA or 0.9% over output range, which helps keep the loop bandwidth of the charge pump phase-locked loop (PLL) fixed and maximise the dynamic range. Extremely low power adaptive bias circuits are proposed to provide body-bias compensation at different output voltage levels. It is believed that the current variation is the minimum among the published results of PLL charge pumps.
Autors: Liu, P.;Sun, P.;Jung, J.;Heo, D.;
Appeared in: Electronics Letters
Publication date: Jan 2012, volume: 48, issue:1, pages: 16 - 18
Publisher: IEEE
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» Plug-ins proliferate
Abstract:
Do you own a plug-in car? Do you even know anybody who does? Probably not. But that might very well change this year. Electric cars aren??t new, of course. Mitsubishi??s all-electric i-MiEV has been available in several countries since 2010. The US $35 200 Nissan Leaf, another pure electric vehicle, has been selling in Japan and the United States for more than a year. The Chevy Volt is also
Autors: Schneider, D.;
Appeared in: IEEE Spectrum
Publication date: Jan 2012, volume: 49, issue:1, pages: 36 - 37
Publisher: IEEE
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» PNUTS in Flight: Web-Scale Data Serving at Yahoo
Abstract:
Data management for stateful Web applications is extremely challenging. Applications must scale as they grow in popularity, serve their content with low latency on a global scale, and be highly available, even in the face of hardware failures. This need has generated a new class of Internet-scale data management systems. Yahoo has more than 100 user-facing applications and numerous internal platforms. To meet its data management needs, it built the PNUTS system. Here, the authors review PNUTS' growing adoption, point to specific applications, and detail several of PNUTS' features.
Autors: Silberstein, Adam;Chen, Jianjun;Lomax, David;McMillan, Brad;Mortazavi, Masood;Narayan, P.P.S.;Ramakrishnan, Raghu;Sears, Rusty;
Appeared in: IEEE Internet Computing
Publication date: Jan 2012, volume: 16, issue:1, pages: 13 - 23
Publisher: IEEE
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» Point defect states of exchange spin waves in all-ferromagnetic two-dimensional magnonic crystals
Abstract:
Using the plane-wave expansion method under supercell approximation, band structures of exchange spin waves propagating in all-ferromagnetic two-dimensional magnonic crystals with point defects are calculated. The results indicate that the point defects in these structures can create localized states inside the bandgap. The characteristics and the magnetization distributions of these localized states are studied. The results show that the group velocities of the localized states almostequal zero in the whole first Brillouin zone, and numbers of localized states and their frequency-positions in the bandgap are related to the size of the point defect. Magnonic crystalswith such defect states can be used as fabricating materials of narrow bandpass spin-wave filters.
Autors: Yang, Hui;Yun, Guohong;Cao, Yongjun;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:1, pages: 013908 - 013908-5
Publisher: IEEE
Full litterature document
 
» Poisson image denoising using fast discrete curvelet transform and wave atom
Abstract:

Highlights

? Poisson image denoising using the multiscale variance stabilizing transform (MSVST). ? Combines MSVST with FDCT, wave atom and their mirror extended versions. ? Simulations shows very good denoising performance. ? Performance comparable with platelet, PURELET.


Autors: In this paper, we propose a strategy to combine fast discrete curvelet transform (FDCT) and wave atom (WA) with multiscale variance stabilizing transform (MS-VST); our objective is to develop algorithms for Poisson noise removal from images. Applying
Appeared in: Signal Processing
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Polarimetry With Phased Array Antennas: Theoretical Framework and Definitions
Abstract:
For phased array receivers, the accuracy with which the polarization state of a received signal can be measured depends on the antenna configuration, array calibration process, and beamforming algorithms. A signal and noise model for a dual-polarized array is developed and related to standard polarimetric antenna figures of merit, and the ideal polarimetrically calibrated, maximum-sensitivity beamforming solution for a dual-polarized phased array feed is derived. A practical polarimetric beamformer solution that does not require exact knowledge of the array polarimetric response is shown to be equivalent to the optimal solution in the sense that when the practical beamformers are calibrated, the optimal solution is obtained. To provide a rough initial polarimetric calibration for the practical beamformer solution, an approximate single-source polarimetric calibration method is developed. The modeled instrumental polarization error for a dipole phased array feed with the practical beamformer solution and single-source polarimetric calibration was dB or lower over the array field of view for elements with alignments perturbed by random rotations with 5 degree standard deviation.
Autors: Warnick, K. F.;Ivashina, M. V.;Wijnholds, S. J.;Maaskant, R.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2012, volume: 60, issue:1, pages: 184 - 196
Publisher: IEEE
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» Polarization reversal and jump-like domain wall motion in stoichiometric LiTaO3 produced by vapor transport equilibration
Abstract:
The polarization reversal and domain structure evolution has been studied in stoichiometric lithium tantalate prepared by vapor transport equilibration process. The first in situ visualization of domain kinetics has demonstrated the jump-like motion of few strictly oriented plane domain walls, which leads to short isolated current pulses in the switching current data. The proposed model of jump-like domain wall motion caused by interaction with pinning centers representing the areas with increased value of the threshold field is based on the effect of retardation of bulk screening. The derived formulas were applied successfully for analysis of the field dependence of the total switching time. The durations of wall jumps and wall stays (rest times) extracted from the switching current data are analyzed separately. The deceleration of the wall motion velocity during jump is controlled by the trail of residual depolarization field produced by bound charges and screening charges in the area behind the wall. The duration of the rest time is governed by the bulk screening of residual depolarization field. The value of Hurst exponent 0.75 obtained by fractal analysis of the switching current data has confirmed the essential influence of prehistory on the domain wall motion. The measurements of the coercive field by switching in bipolar triangular pulses in wide range of the field ramp rate have allowed us to extract the record low value of coercive field 60 V/mm for quasi-static polarization reversal.
Autors: Shur, V. Ya.;Akhmatkhanov, A. R.;Baturin, I. S.;Shishkina, E. V.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:1, pages: 014101 - 014101-8
Publisher: IEEE
Full litterature document
 
» Porphyrins modified with a low-band-gap chromophore for dye-sensitized solar cells
Abstract:
image

Highlights

? Two novel porphyrin dyes were designed and synthesized. ? The absorption spectra were broadened and the red-shifted due to introduce the low-band-gap chromophore. ? The dye-sensitized solar cell based on the dyePMBTZobtained a solar-to-electric power conversion efficiency of 5.46%.

Autors:

Graphical abstract

Two novel porphyrin dyes linked the low-band-gap chromophore were d
Appeared in: Organic Electronics
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Positive Gate-Bias Temperature Stability of RF-Sputtered Active-Layer Thin-Film Transistors
Abstract:
This paper investigates the positive gate-bias temperature stability of RF-sputtered bottom-gate active-layer thin-film transistors (TFTs) annealed at 200 for 5 h and 350 for 30 min. Although the TFT devices initially exhibited similar electrical characteristics, the TFTs annealed at 350 demonstrated stability characteristics superior to those annealed at 200 . This result is due to the improved crystallinity and more stable phase with greater proportion of Zn replaced by Mg in the ZnO crystals. The results also reveal a hump shape in the subthreshold region of the transfer characteristics, which is induced by the positive gate-bias stress at elevated temperatures. The hump phenomenon was suppressed in the TFT annealed at 350 . The hump disappeared shortly after removing the positive gate bias, suggesting that this phenomenon was meta-stable and resulted from gate-bias-induced electric field. One possible mechanism responsible for the hump formation in the transfer curve is the gate-field-induced back-channel parasitic transistor. Alternatively, this hump phenomenon might have been due to the creation of meta-stable vacancies in which the neutral defects were thermally excited and released electrons into the active layer to form a leakage path when the TFTs were subjected to gate-bias stress at elevated temperatures.
Autors: Tsai, Y.-S.;Chen, J.-Z.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2012, volume: 59, issue:1, pages: 151 - 158
Publisher: IEEE
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» Positive Invariance of Constrained Affine Dynamics and Its Applications to Hybrid Systems and Safety Verification
Abstract:
Motivated by long-time dynamic analysis of hybrid systems and safety verification problems, this paper addresses fundamental positive invariance issues of an affine dynamical system on a general polyhedron and their applications. Necessary and sufficient algebraic conditions are established for the existence of a positively invariant set of an affine system on a polyhedron using the tools of lexicographic relation and long-time oscillatory dynamic analysis. A linear program based algorithm is proposed to verify these conditions, and its computational complexity is analyzed. The positive invariance results are applied to obtain an explicit characterization of global switching behaviors of piecewise affine systems. Further, the positive invariance techniques developed in this paper are exploited to show the decidability of safety verification of a class of affine dynamics on semialgebraic sets.
Autors: Shen, J.;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jan 2012, volume: 57, issue:1, pages: 3 - 18
Publisher: IEEE
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» Postdeposition Anneal on Structural and Sensing Characteristics of High-   Electrolyte–Insulator–Semiconductor pH Sensors
Abstract:
In this letter, we develop an electrolyte–insulator–semiconductor (EIS) device using a high-   sensing membrane deposited on a Si substrate through cosputtering. We used X-ray diffraction and X-ray photoelectron spectroscopy to study the structural properties of these films annealed at various temperatures. The EIS device incorporating an sensing film annealed at 900 exhibited a higher sensitivity of 58.4 mV/pH, a lower hysteresis voltage of 4.6 mV, and a smaller drift rate of 1.2 mV/h than other annealing temperatures, presumably suggesting the formation of a well-crystallized film and a thinner silicate layer at the oxide/Si interface.
Autors: Pan, T.-M.;Lin, C.-W.;Hsu, B.-K.;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2012, volume: 33, issue:1, pages: 116 - 118
Publisher: IEEE
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» Postsilicon Tuning of Standby Supply Voltage in SRAMs to Reduce Yield Losses Due to Parametric Data-Retention Failures
Abstract:
Lowering the supply voltage of static random access memories (SRAMs) during standby modes is an effective technique to reduce their leakage power consumption. To maximize leakage reductions, it is desirable to reduce the supply voltage as much as possible. SRAM cells can retain their data down to a certain voltage, called the data-retention voltage (DRV). Due to intra-die variations in process parameters, the DRV of cells differ within a single memory die. Hence, the minimum applicable standby voltage to a memory die is determined by the maximum DRV among its constituent cells. On the other hand, inter-die variations result in a die-to-die variation of . Applying an identical standby voltage to all dies, regardless of their corresponding , can result in the failure of some dies, due to data-retention failures (DRFs), entailing yield losses. In this work, we first show that the yield losses can be significant if the standby voltage of SRAMs is reduced aggressively. Then, we propose a postsilicon standby voltage tuning scheme to avoid the yield losses due to DRFs, while reducing the leakage currents effectively. Simulation results in a 45-nm predictive technology show that tuning standby voltage of SRAMs can enhance data-retention yield by 10%–50%.
Autors: Nourivand, A.;Al-Khalili, A. J.;Savaria, Y.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jan 2012, volume: 20, issue:1, pages: 29 - 41
Publisher: IEEE
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» Power Control Game in Multi-Terminal Covert Timing Channels
Abstract:
We present a game theoretic power control of overlay/overt communications to maximize the goodput (effective throughput of error-free bits) of multi-terminal covert timing channels. Most approaches in the literature on covert timing channels discuss capacities of the timing channels but do not study how the overlay communication can be controlled to maximize the goodput of covert timing channels. We study the factors of the overlay communication that affect the goodput of each timing channel in a multi-terminal covert timing network. We show that the goodput of the covert timing channel can be enhanced by increasing the rate of overlay transmission and by game theoretic power control of overlay communication. We finally extend the game theoretic power control to maximize the goodput of each covert timing channel in a multi-terminal covert timing network by maximizing the asymptotic spectral efficiency of the overlay communication.
Autors: Anand, S.;Sengupta, S.;Hong, K.;Chandramouli, R.;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Jan 2012, volume: 30, issue:1, pages: 44 - 53
Publisher: IEEE
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» Power effect of ZnO:Al film as back reflector on the performance of thin-film solar cells
Abstract:
Aluminum-doped zinc oxide (AZO) is attracting interest as a potential transparent conducting oxide material for use in amorphous silicon (a-Si) thin-film solar cells. The absorption loss in the n-a-Si:H/Ag interface of the p-i-n thin film solar is high because the extinction coefficient of the Ag that is used as a back reflector is high. In this work, transparent conducting AZO films with a power in the range 500 W to 900 W prepared under Ar-ambient at a substrate temperature of 25 °C by RF-magnetron in-line sputtering. To minimize the absorption loss at longer wavelengths, an AZO layer we inserted at the n-a-Si:H/Ag interface of a solar cell with a glass/SnO2:F/p-a-SiC:H/buffer-layer/i-a-Si:H/n-a-Si:H/Ag structure and the performance of the cell with AZO/Ag deposited instead of Ag on the back contact, was investigated. The effects of the RF-magnetron sputtering deposition parameters on the optical, electrical and structural properties of the AZO films were analyzed. Optimized AZO films with high transmittance (> 80%) and low resistivity (1.47 × 10-3 Ω-cm) in the wavelength range 400–800 nm were obtained under the sputtering conditions. The p-i-n a-Si solar cell with the AZO/Ag back contact had a conversion efficiency of 9.42%, which was higher than that (7.36%) of the cell without the AZO/Ag back contact. Light-soaking of these cells for 1000 h at 60 °C led to stabilization at 8.32% for the best cell. The relative typical efficiency degradation of about 10% for single-junction cells demonstrates that this treatment does not negatively influence stability.
Autors: Lin, Yang-Shih;Lien, Shui-Yang;Wang, Chao-Chun;Liu, Chueh-Yang;Nautiyal, Asheesh;Wuu, Dong-Sing;Tsai, Pi-Chuen;Chen, Chia-Fu;Lee, Shuo-Jen;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2012, volume: 30, issue:1, pages: 011302 - 011302-5
Publisher: IEEE
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» Power grid analysis and verification considering temperature variations
Abstract:
Process variations significantly impact leakage power, a pivotal parameter in designing a power grid. Because of the strong relationship between temperature and leakage power, the variations also impose statistical behavior on the operating temperature. In addition, the metal resistivity of a power grid increases with temperature. Therefore, ignoring the interdependency between leakage and temperature can introduce large errors in the power grid design. In this paper, a power grid analysis is proposed considering a statistical thermal profile across the grid. In addition, an efficient verification method is provided that ensures the robustness of the power grid in the presence of variations. A reliable estimation of the statistical thermal profile at the architecture level makes it possible to address any voltage violation early in the design process.
Autors: Kian Haghdad, Javid Jaffari, Mohab Anis
Appeared in: Microelectronics Journal
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Power SiC DMOSFET Model Accounting for Nonuniform Current Distribution in JFET Region
Abstract:
The main goal of this paper is development of a new circuit-based silicon carbide (SiC) DMOSFET model which physically represents the mechanism of current saturation in power SiC DMOSFET. Finite-element simulations show that current saturation for a typical device geometry is due to 2-D carrier distribution effects in the JFET region caused by current spreading from the channel to the JFET region. For high drain-source voltages, most of the voltage drop occurs in the current spreading region located in the JFET region close to the channel. A new model is proposed that represents the nonuniform current distribution in the JFET region using a nonlinear voltage source and a resistance network. Advantages of the proposed model are that a single set of equations describes operation in both the linear and saturation regions, and that it provides a more physical description of MOSFET operation.
Autors: Fu, R.;Grekov, A.;Hudgins, J.;Mantooth, A.;Santi, E.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2012, volume: 48, issue:1, pages: 181 - 190
Publisher: IEEE
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» Power-Aware High-Level Synthesis With Clock Skew Management
Abstract:
An effective clock-skew scheduling scheme in the high-level synthesis process targeted for power and speed optimization is presented. The proposed scheme has the following distinctive features: 1) a clock-skew management algorithm that selects a minimum set of clock phases to achieve the optimization goals is developed; 2) the effect of module binding in high-level synthesis was not considered in previous studies, which may lead to designs with timing violation; a discussion on how to model the effect of module binding is provided; 3) a heuristic low-power module binding algorithm that provides near-optimal results quickly is proposed; and 4) a technique called reallocation is proposed to exploit all available skews and thus maximize the capability of clock-skew scheduling. Experimental results show that, on the average, 48% power reduction is achieved by the proposed method. At most five clock phases are required, while in most cases two to four clock phases are sufficient.
Autors: Yeh, T.-H.;Wang, S.-J.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jan 2012, volume: 20, issue:1, pages: 167 - 171
Publisher: IEEE
Full litterature document
 
» Power-aware provisioning strategy with shared path protection in optical WDM networks
Abstract:

Highlights

? We study the power-aware connection provisioning strategies in optical WDM networks. ? We illustrate the conflict between network power efficiency and blocking probability. ? We propose a sleep mode based Power-Aware Shared Path Protection (PASPP) algorithm. ? PASPP can obtain notable power saving in optical WDM networks. ? PASPP can achieve satisfactory tradeoff between power efficiency and blocking probability.


Autors: As the Internet continues to grow, the power consumption of telecommunication networks is rising at a considerable speed, which seriously increases the operational expenditure and greenhouse gas emission. Since optical Wavelength Division Multiplexin
Appeared in: Optical Fiber Technology
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Power-Constrained Contrast Enhancement for Emissive Displays Based on Histogram Equalization
Abstract:
A power-constrained contrast-enhancement algorithm for emissive displays based on histogram equalization (HE) is proposed in this paper. We first propose a log-based histogram modification scheme to reduce overstretching artifacts of the conventional HE technique. Then, we develop a power-consumption model for emissive displays and formulate an objective function that consists of the histogram-equalizing term and the power term. By minimizing the objective function based on the convex optimization theory, the proposed algorithm achieves contrast enhancement and power saving simultaneously. Moreover, we extend the proposed algorithm to enhance video sequences, as well as still images. Simulation results demonstrate that the proposed algorithm can reduce power consumption significantly while improving image contrast and perceptual quality.
Autors: Lee, C.;Lee, C.;Lee, Y.-Y.;Kim, C.-S.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jan 2012, volume: 21, issue:1, pages: 80 - 93
Publisher: IEEE
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» Power-Line Communication in Medium-Voltage System: Simulation Model and Onfield Experimental Tests
Abstract:
The aim of this paper is to develop a complete model of a power-line communication (PLC) system operating on a medium-voltage (MV) network. The core-shield configuration was chosen for signal transmission in the power cables. In order to validate the developed model experimental, the medium-voltage network of the Favignana island was used to carry out detailed testing. The transmission was performed between two transformer substations in the presence of mains voltage (i.e., 24 kV). ST7540 FSK power-line transceivers, together with capacitive coupling interfaces, were used for the transmission and the reception of the communication signal. The correlation between the experimental measurements and the simulation results would appear to validate the use of the developed model for the analysis of MV transmission channels.
Autors: Cataliotti, A.;Di Cara, D.;Fiorelli, R.;Tine, G.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jan 2012, volume: 27, issue:1, pages: 62 - 69
Publisher: IEEE
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» Power-Scalable, Complex Bandpass/Low-Pass Filter With I/Q Imbalance Calibration for a Multimode GNSS Receiver
Abstract:
A power-scalable reconfigurable filter with in-phase/quadrature (I/Q) imbalance calibration for a multimode Global Navigation Satellite Systems (GNSS) receiver is presented. The filter is reconfigurable as either a fifth-order complex bandpass filter exhibiting a tunable intermediate frequency (4.092, 6.138, 10.23, 12.296, 13.29, 18.4, and 20.442 MHz) and bandwidth (2.2, 4.2, 8, 10, and 18 MHz) or a third-order low-pass filter with tunable bandwidth (5 and 9 MHz). A flexible current-reuse operational amplifier with a power-scaling technique is proposed to lower the power consumption, and the image-rejection ratio is improved by almost 20 dB by introducing an I/Q imbalance calibration circuit before the filter. The filter, which was implemented in 65-nm CMOS, consumes 2.9–19.5 mW in different modes, with the I/Q calibration circuit consuming 0.9 mW.
Autors: Xu, Y.;Chi, B.;Yu, X.;Qi, N.;Chiang, P.;Wang, Z.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jan 2012, volume: 59, issue:1, pages: 30 - 34
Publisher: IEEE
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» Powering a Ventricular Assist Device (VAD) With the Free-Range Resonant Electrical Energy Delivery (FREE-D) System
Abstract:
Wireless data communication technology has eliminated wired connections for data transfer to portable devices. Wireless power technology offers the possibility of eliminating the remaining wired connection: the power cord. For ventricular assist devices (VADs), wireless power technology will eliminate the complications and infections caused by the percutaneous wired power connection. Integrating wireless power technology into VADs will enable VAD implants to become a more viable option for heart failure patients (of which there are 80 000 in the United States each year) than heart transplants. Previous transcutaneous energy transfer systems (TETS) have attempted to wirelessly power VADs ; however, TETS-based technologies are limited in range to a few millimeters, do not tolerate angular misalignment, and suffer from poor efficiency. The free-range resonant electrical delivery (FREE-D) wireless power system aims to use magnetically coupled resonators to efficiently transfer power across a distance to a VAD implanted in the human body, and to provide robustness to geometric changes. Multiple resonator configurations are implemented to improve the range and efficiency of wireless power transmission to both a commercially available axial pump and a VentrAssist centrifugal pump . An adaptive frequency tuning method allows for maximum power transfer efficiency for nearly any angular orientation over a range of separation distances. Additionally, laboratory results show the continuous operation of both pumps using the FREE-D system with a wireless power transfer efficiency upwards of 90%.
Autors: Waters, B. H.;Sample, A. P.;Bonde, P.;Smith, J. R.;
Appeared in: Proceedings of the IEEE
Publication date: Jan 2012, volume: 100, issue:1, pages: 138 - 149
Publisher: IEEE
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» Pre-sampled data based prediction control for active power filters
Abstract:

Highlights

? A prediction control based on pre-sampled data for active power filters is presented in this paper. ? The pre-sampled data can be obtained from sampled data in previous fundamental cycle. ? The reference current is calculated by the predicted current values in few steps ahead. ? The active filter current phase delay can be effectively compensated. ? The proposed prediction method is simple and easy for practical application.


Autors: A prediction control based on pre-sampled data from previous fundamental cycle for active power filters is presented in this paper. In which the reference current is calculated by the predicted current values in few steps ahead. In this way the activ
Appeared in: International Journal of Electrical Power & Energy Systems
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Pre-treatment of agro-industrial wastes used as alternative nutrients for rearingCydia pomonella
Abstract:

Highlights

? Diet for breeding of codling moth using agro-industrial wastes by pre-treatment. ? Pre-treatment increases nutrient concentration, reduces viscosity and particle size. ? Profitable for breeding of the codling moth larva by increasing nutrient assimilation. ? Can reduce cost of biopesticide produced from larva cultivated on its diets.


Autors: The physico-chemical and nutritional potential of starch industry wastewater (SIW), brewery wastewater (BWW) and apple pomace sludge (POM) and municipal wastewater sludge (WWS) were compared. The results showed higher nutrient content for BWW (19.52 
Appeared in: Biosystems Engineering
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Precision AC–DC Transfer Measurements With a Josephson Waveform Synthesizer and a Buffer Amplifier
Abstract:
Measurements of the ac–dc difference of a thermal converter have been performed using a Josephson waveform synthesizer and a precision buffer amplifier at frequencies from 10 Hz to 4 kHz, showing agreement with conventional standards of better than 1 up to 1 kHz. In addition, a method of finding the operating parameters of the programmable Josephson array that corresponds to minimal uncertainty is discussed.
Autors: Seron, O.;Djordjevic, S.;Budovsky, I.;Hagen, T.;Behr, R.;Palafox, L.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2012, volume: 61, issue:1, pages: 198 - 204
Publisher: IEEE
Full litterature document
 
» Preconditioning for Edge-Preserving Image Super Resolution
Abstract:
We propose a simple preconditioning method for accelerating the solution of edge-preserving image super-resolution (SR) problems in which a linear shift-invariant point spread function is employed. Our technique involves reordering the high-resolution (HR) pixels in a similar manner to what is done in preconditioning methods for quadratic SR formulations. However, due to the edge preserving requirements, the Hessian matrix of the cost function varies during the minimization process. We develop an efficient update scheme for the preconditioner in order to cope with this situation. Unlike some other acceleration strategies that round the displacement values between the low-resolution (LR) images on the HR grid, the proposed method does not sacrifice the optimality of the observation model. In addition, we describe a technique for preconditioning SR problems involving rational magnification factors. The use of such factors is motivated in part by the fact that, under certain circumstances, optimal SR zooms are nonintegers. We show that, by reordering the pixels of the LR images, the structure of the problem to solve is modified in such a way that preconditioners based on circulant operators can be used.
Autors: Pelletier, S.;Cooperstock, J. R.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jan 2012, volume: 21, issue:1, pages: 67 - 79
Publisher: IEEE
Full litterature document
 
» PREDICT - Decision support system for load forecasting and inferen A new undertaking for Brazilian power suppliers
Abstract:

Highlights

? We implement a novel decision support system for Brazilian power suppliers. ? Statistical and computational intelligence models are evaluated for the domain. ? A hybrid load forecasting framework proved greater accuracy to the time series. ? Correlation studies are implemented for improving decision support of managers. ? Results allow for better estimating consumption and evaluate its impacting factors.


Autors: One of the most desired aspects for power suppliers is the acquisition/sale of energy for a future demand. However, power consumption forecast is characterized not only by the variables of the power system itself, but also related to social-economic
Appeared in: International Journal of Electrical Power & Energy Systems
Publication date: Jan 2012
Publisher: Elsevier B.V.
Full litterature document
 
» Predicting Metal-Binding Sites from Protein Sequence
Abstract:
Prediction of binding sites from sequence can significantly help toward determining the function of uncharacterized proteins on a genomic scale. The task is highly challenging due to the enormous amount of alternative candidate configurations. Previous research has only considered this prediction problem starting from 3D information. When starting from sequence alone, only methods that predict the bonding state of selected residues are available. The sole exception consists of pattern-based approaches, which rely on very specific motifs and cannot be applied to discover truly novel sites. We develop new algorithmic ideas based on structured-output learning for determining transition-metal-binding sites coordinated by cysteines and histidines. The inference step (retrieving the best scoring output) is intractable for general output types (i.e., general graphs). However, under the assumption that no residue can coordinate more than one metal ion, we prove that metal binding has the algebraic structure of a matroid, allowing us to employ a very efficient greedy algorithm. We test our predictor in a highly stringent setting where the training set consists of protein chains belonging to SCOP folds different from the ones used for accuracy estimation. In this setting, our predictor achieves 56 percent precision and 60 percent recall in the identification of ligand-ion bonds.
Autors: Passerini, Andrea;Lippi, Marco;Frasconi, Paolo;
Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics
Publication date: Jan 2012, volume: 9, issue:1, pages: 203 - 213
Publisher: IEEE
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» Predicting soil chemical composition and other soil parameters from field observations using a neural network
Abstract:

Highlights

? Data from the National Soil Inventory of Scotland was analysed with neural networks. ? Good prediction was made for a range of soil chemical and physical properties. ? This work could lead to characterisation of soil ecosystem services in the field.


Autors: Characterisation of soils in relation to a particular use or classification system is often heavily dependant on their chemical properties, requiring detailed, time-consuming and often expensive laboratory analysis. If it were possible to gain even p
Appeared in: Computers and Electronics in Agriculture
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Prediction ability of a new minimum bubbling criterion
Abstract:
image

Highlights

? Accurate minimum bubbling points were obtained from?dandUdexpansion curves. ? Brandani and Zhang stability criterion was validated, using this data points. ? A modified drag force correlation was proposed. ? A characteristic length was found to be an exponential function with voidage. ? Modified Brandani and Zhang stability criterion was proposed.

Autors:

Graphical abstract

Appeared in: Advanced Powder Technology
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Predictions of apple bruise volume using artificial neural network
Abstract:

Highlights

? Neural bruise estimation models were constructed to calculate apple bruise volume. ? Models were built based upon impact force and impact energy as main input network. ? BB training algorithm compared with BDLRF algorithm. ? BDLRF has a better performance for the prediction of apple bruise volume. ? An artificial neural network is able to predict apple bruise volume better than a linear regression model.


Autors: Bruise damage is a major cause of fruit quality loss. Bruises occur under dynamic and static loading when stress induced in the fruit exceeds the failure stress of the fruit tissue. In this article the potential of an artificial neural network (ANN)
Appeared in: Computers and Electronics in Agriculture
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Preface to the special issue on latent variable analysis and signal separation
Abstract:
V. Vigneron, V. Zarzoso, R. Gribonval, E. Vincent
Autors: Source: Signal Processing, Available online 5 January 2012
Appeared in: Signal Processing
Publication date: Jan 2012
Publisher: Elsevier B.V.
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» Principal Component Localization in Indoor WLAN Environments
Abstract:
This paper presents a novel approach to building a WLAN-based location fingerprinting system. Our algorithm intelligently transforms received signal strength (RSS) into principal components (PCs) such that the information of all access points (APs) is more efficiently utilized. Instead of selecting APs, the proposed technique replaces the elements with a subset of PCs to simultaneously improve the accuracy and reduce the online computation. Our experiments are conducted in a realistic WLAN environment. The results show that the mean error is reduced by 33.75 percent, and the complexity by 40 percent, as compared to the existing methods. Moreover, several benefits of our algorithm are demonstrated, such as requiring fewer training samples and enhancing the robustness to RSS anomalies.
Autors: Fang, Shih-Hau;Lin, Tsungnan;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2012, volume: 11, issue:1, pages: 100 - 110
Publisher: IEEE
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» Principles of a Micro-Rate Integrating Ring Gyroscope
Abstract:
Most micromachined vibratory gyroscopes may be classified as "rate" gyroscopes where it is angular rate that is measured. Rate integrating gyroscopes measure the orientation angle directly. The operating principles of the micro-rate integrating ring gyroscope in the presence of imperfections are presented here. A relationship between the angle error, the imperfections, and applied angular rate is derived for the purpose of establishing the fabrication tolerances required for a particular applied angular rate.
Autors: Gallacher, B. J.;
Appeared in: IEEE Transactions on Aerospace and Electronic Systems
Publication date: Jan 2012, volume: 48, issue:1, pages: 658 - 672
Publisher: IEEE
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» Probabilistic determination of pilot points for zonal voltage control
Abstract:
Owing to the local nature of voltage and reactive power control, the voltage control is managed in a zonal or regional basis. A new comprehensive scheme for optimal selection of pilot points is proposed in this study. The uncertainties of operational and topological disturbances of the power system are included to provide the robustness of the pilot node set. To reduce the huge number of probable states (i.e. combined states of load and topological changes), a scenario reduction technique is used. The resulted optimal control problem is solved using a new immune-based genetic algorithm. The performance of the proposed method is verified over IEEE 118-bus and realistic Iranian 1274-bus national transmission grids.
Autors: Amraee, T.;Soroudi, A.;Ranjbar, A.M.;
Appeared in: IET Generation, Transmission & Distribution
Publication date: Jan 2012, volume: 6, issue:1, pages: 1 - 10
Publisher: IEEE
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» Probabilistic Exposure Fusion
Abstract:
The luminance of a natural scene is often of high dynamic range (HDR). In this paper, we propose a new scheme to handle HDR scenes by integrating locally adaptive scene detail capture and suppressing gradient reversals introduced by the local adaptation. The proposed scheme is novel for capturing an HDR scene by using a standard dynamic range (SDR) device and synthesizing an image suitable for SDR displays. In particular, we use an SDR capture device to record scene details (i.e., the visible contrasts and the scene gradients) in a series of SDR images with different exposure levels. Each SDR image responds to a fraction of the HDR and partially records scene details. With the captured SDR image series, we first calculate the image luminance levels, which maximize the visible contrasts, and then the scene gradients embedded in these images. Next, we synthesize an SDR image by using a probabilistic model that preserves the calculated image luminance levels and suppresses reversals in the image luminance gradients. The synthesized SDR image contains much more scene details than any of the captured SDR image. Moreover, the proposed scheme also functions as the tone mapping of an HDR image to the SDR image, and it is superior to both global and local tone mapping operators. This is because global operators fail to preserve visual details when the contrast ratio of a scene is large, whereas local operators often produce halos in the synthesized SDR image. The proposed scheme does not require any human interaction or parameter tuning for different scenes. Subjective evaluations have shown that it is preferred over a number of existing approaches.
Autors: Song, M.;Tao, D.;Chen, C.;Bu, J.;Luo, J.;Zhang, C.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jan 2012, volume: 21, issue:1, pages: 341 - 357
Publisher: IEEE
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» Probabilistic parallel measurement of network traffic at multiple locations
Abstract:
Measuring the per-flow traffic in large networks is very challenging due to the high performance requirements. In addition to that, if traffic is measured at multiple points in the network at the same time, it becomes necessary to merge the observations in order to obtain network-wide statistics. When doing so, packets must be accounted for only once, even if they traverse more than one measurement point. Today??s standard technique, sampling-based traffic accounting, results in large approximation errors. Here, we describe an approach named Distributed Probabilistic Counting (DPC). DPC is based on a probabilistic data representation. It provides accurate traffic statistics at very low per-packet effort, and is able to merge measurement from multiple network locations while counting each distinct packet only once.
Autors: Marold, A.;Lieven, P.;Scheuermann, B.;
Appeared in: IEEE Network
Publication date: Jan 2012, volume: 26, issue:1, pages: 6 - 12
Publisher: IEEE
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» Probing band-tail states in silicon metal-oxide-semiconductor heterostructures with electron spin resonance
Abstract:
We present an electron spin resonance (ESR) approach to characterize shallow electron trapping in band-tail states at Si/SiO2 interfaces in metal-oxide-semiconductor (MOS) devices and demonstrate it on two MOS devices fabricated at different laboratories. Despite displaying similar low temperature (4.2 K) peak mobilities, our ESR data reveal a significant difference in the Si/SiO2 interface quality of these two devices, specifically an order of magnitude difference in the number of shallow trapped charges at the Si/SiO2 interfaces. Thus, our ESR method allows a quantitative evaluation of the Si/SiO2 interface quality at low electron densities, where conventional mobility measurements are not possible.
Autors: Jock, R. M.;Shankar, S.;Tyryshkin, A. M.;He, Jianhua;Eng, K.;Childs, K. D.;Tracy, L. A.;Lilly, M. P.;Carroll, M. S.;Lyon, S. A.;
Appeared in: Applied Physics Letters
Publication date: Jan 2012, volume: 100, issue:2, pages: 023503 - 023503-3
Publisher: IEEE
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» Probing compositional disorder in vanadium oxide thin films grown on atomic layer deposited hafnia on silicon by capacitance spectroscopy
Abstract:
The authors investigate capacitance-voltage characteristics of HfO2/VOx/HfO2/n-Si metal-oxide semiconductor devices that include vanadium oxide (VOx) films of different composition. Temperature dependent capacitance-voltage measurements are reported spanning the metal-insulator transition boundary of VOx films. The measured trends in dielectric properties are cross-correlated with resistance ratio change and oxidation state in identical films. The results could be of relevance to advancing synthesis of correlated oxide films on dielectric layers and further utilizing capacitance spectroscopy as a way to probe oxide stoichiometry in gated heterostructures.
Autors: Ko, Changhyun;Zhou, You;Ramanathan, Shriram;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2012, volume: 30, issue:1, pages: 011501 - 011501-7
Publisher: IEEE
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» Probing grain boundaries in ceramic scintillators using x-ray radioluminescence microscopy
Abstract:
X-ray radioluminescence microscopy (XRLM), a novel fluorescence microscopy technique under focused x-ray excitation, was used to characterize micro-scale luminescence of Eu:Y2O3 and Ce:YAG transparent ceramics and bicrystals. The diffusion length of a known semiconductor measured by XRLM was found to be in agreement with previously measured values, illustrating its use for characterizing charge carrier transport. Emission intensity was found to drop at the boundaries in both Eu:Y2O3 and Ce:YAG ceramics and bicrystals. The depletion in emission at grain boundaries was ultimately found to be related to charge carrier depletion (through either deep trapping or non-radiative recombination). A charge carrier diffusion model was used to understand the effect of grain boundaries on charge carrier transport in these scintillators. The diffusion model was found to accurately predict the spatial distribution of emission in a Ce:YAG single-crystal as a function of x-ray excitation energy. Structural and chemical characterization of grain boundaries in an Eu:Y2O3 ceramic using transmission electron microscopy and secondary ion mass spectrometry mapping showed an ordered boundary region and no detectable segregation of impurities or Eu, justifying the use of an abrupt boundary condition to determine boundary recombination velocities in these materials. The boundary recombination velocities were then used to show that, for ceramics with grain sizes > ∼20 μm, there would be a minimal effect from the detected charge carrier depletion at grain boundaries on their bulk x-ray radioluminescence intensity. Ultimately, this study illustrates how this new XRLM technique can be used to measure charge carrier diffusion properties and how it may be coupled with microstructural and micro-scale chemical analyses to fully investigate the effect of grain boundaries on scintillator properties.
Autors: Podowitz, Stephen R.;Gaume, Romain M.;Feigelson, Robert S.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2012, volume: 111, issue:1, pages: 013520 - 013520-12
Publisher: IEEE
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» Probing local surface conductance using current sensing atomic force microscopy
Abstract:
We have analyzed correlations between surface morphology and current sensing images obtained using a current sensing atomic force microscope (CSAFM) and the implication of surface conductivity derived from the current sensing images. We found that in cases where the diameter of a CSAFM probe tip is much smaller than the correlation length of the surface morphological features, the current detected using the probe should have little correlation with the surface features imaged by the same probe. If the sample thickness is much larger than the tip size, the surface conductivity distribution of a sample can be derived from a current sensing image using the Holm resistance relation, and the current probed using a CSAFM reflects the conductance variations in a layer on the surface with the thickness comparable to the probe diameter. However, if the thickness of a sample is comparable to or smaller than the tip diameter, CSAFM measures the conductance across the entire portion of the sample sandwiched between the tip and the electrode.
Autors: Liu, Yucong;He, Jiayu;Kwon, Osung;Zhu, Da-Ming;
Appeared in: Review of Scientific Instruments
Publication date: Jan 2012, volume: 83, issue:1, pages: 013701 - 013701-5
Publisher: IEEE
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