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Electrical and Electronics Engineering publications abstract of: 01-2011 sorted by title, page: 21
» Structural and optical properties of InGaN–GaN nanowire heterostructures grown by molecular beam epitaxy
Abstract:
InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaN to higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, μ-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.
Autors: Limbach, F.;Gotschke, T.;Stoica, T.;Calarco, R.;Sutter, E.;Ciston, J.;Cusco, R.;Artus, L.;Kremling, S.;Hofling, S.;Worschech, L.;Grutzmacher, D.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 014309 - 014309-6
Publisher: IEEE
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» Structural assessment of a solid propellant rocket motor: Effects of aging and damage
Abstract:
The aim of this study is to perform structural analysis of a solid propellant rocket motor using the finite element method and to determine the effects of aging on the analysis results. Thermal and pressure loadings occurring during the shipping, storing and firing are considered to be the most critical in determining long-term behavior of the motor. Stress and strain distribution in the rocket motor under these loading conditions are determined. Maximum hoop strain at the surface of the propellant and bond stresses at the interface between the liner and the insulator are evaluated as indicators of cracking in the...
Autors: H.C., Y?ld?r?m , ?., Özüpek
Appeared in: Aerospace Science and Technology
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Structural, electrical, and strain properties of stoichiometric 1-x-y(Bi0.5Na0.5)TiO3-x(Bi0.5K0.5TiO3)-y(Na0.5K0.5)NbO3 solid solutions
Abstract:
Results on two series of lead-free piezoelectric solid solutions of 1-x-y(Bi0.5Na0.5)TiO3-x(Bi0.5K0.5TiO3)-y(Na0.5K0.5)NbO3 (BNT-BKT-KNN) ceramics, synthesized in the vicinity of ferroelectric rhombohedral (x=0.17) and ferroelectric tetragonal (x=0.20) phase boundary of 1-x(BNT)–xBKT are presented. Orthorhombic KNN in stoichiometric proportion as third component with 0.0≤y≤0.06 is added to prepare these two series (i) with x=0.17 and (ii) with x=0.20. Addition of KNN up to a critical y is observed to improve tetragonality in both series and solid solubility of KNN was verified at least up to y=0.1 in this system. Depolarization temperature Td of these stoichiometric BNT-BKT-KNN series were found to be considerably lower than that of their parent BNT-BKT compositions. As a result of this, coexistence of polar and nonpolar phases for compositions at morphotropic phase boundary (MPB) were indicated at room temperature, resulting in pinched polarization versus electric field (P-E) loops and large strain (strain of ∼0.80% was observed for y=0.01 sample in ×20 series and strain of 0.50% was seen for y=0.04 sample in ×17 series) The MPB of ×17 and ×20 series found to be at y=0- - .04 and y=0.01, respectively.
Autors: Singh, Amrita;Chatterjee, Ratnamala;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 024105 - 024105-5
Publisher: IEEE
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» Structural, optical and electrical properties of Fe-doped SnO2 fabricated by sol-gel dip coating technique
Abstract:
Nanosized Fe3+-doped SnO2 thin film was prepared by the sol-gel dip coating (SGDC) technique on quartz class substrate and sintered at 800°C. The microstructures, surface morphology and optical properties of these films were then characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption measurements, respectively. Electrical properties were analyzed, and resistivity, type and number of carrier concentration, Hall mobility measured as a function of Fe3+ doping and temperature. The XRD spectrum shows the decrease in peak heights as a result of Fe3+-doping while SEM images reveal reduction in crystallite size with increase in Fe3+ content....
Autors: Timonah N., Soitah , Chunhui, Yang , Liang, Sun
Appeared in: Materials Science in Semiconductor Processing
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Structural, optical, and photoluminescence characterization of electron beam evaporated ZnS/CdSe nanoparticles thin films
Abstract:
Structural, optical, and photoluminescence investigations of ZnS capped with CdSe films prepared by electron beam evaporation are presented. X-ray diffraction analysis revealed that the ZnS/CdSe nanoparticles films contain cubic cadmium selenide and hexagonal zinc sulfide crystals and the ZnS grain sizes increased with increasing ZnS thickness. The refractive index was evaluated in terms of envelope method, which has been suggested by Swanepoel in the transparent region. The refractive index values were found to increase with increasing ZnS thickness. However, the optical band gap and the extinction coefficient were decreased with increasing ZnS thickness. Photoluminescence (PL) investigations revealed the presence of two broad emission bands. The ZnS thickness significantly influenced the PL intensities.
Autors: Mohamed, S. H.;Ali, H. M.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013108 - 013108-5
Publisher: IEEE
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» Structural, thermal, optical, and photoacoustic study of nanocrystalline Bi2Te3 produced by mechanical alloying
Abstract:
Nanocrystalline Bi2Te3 was produced by mechanical alloying and its properties were investigated by differential scanning calorimetry (DSC) x-ray diffraction (XRD), Raman spectroscopy (RS), and photoacoustic spectroscopy (PAS). Combining the XRD and RS results, the volume fraction of the interfacial component in as-milled and annealed samples was estimated. The PAS results suggest that the contribution of the interfacial component to the thermal diffusivity of nanostructured Bi2Te3 is very significant.
Autors: Souza, S. M.;Triches, D. M.;Poffo, C. M.;de Lima, J. C.;Grandi, T. A.;de Biasi, R. S.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013512 - 013512-8
Publisher: IEEE
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» Structure and characteristics of ultrathin indium tin oxide films
Abstract:
A series of indium tin oxide (ITO) thin-films with various thicknesses from 2 to 200 monolayers (ML) have been epitaxially grown on LaAlO3 substrates by laser molecular-beam epitaxy. The measurements of x-ray diffraction, atomic force microscopy, four-probe method, and optical transmittance reveal that the film thickness strongly affects the structural, electrical, and optical properties of ITO thin-films, and the ITO thin-films exist at a critical thickness of metal-insulator transition at about 4–5 ML. The electrical transport property has been discussed with the different conductive models.
Autors: Guo, Er-Jia;Guo, Haizhong;Lu, Huibin;Jin, Kuijuan;He, Meng;Yang, Guozhen;
Appeared in: Applied Physics Letters
Publication date: Jan 2011, volume: 98, issue:1, pages: 011905 - 011905-3
Publisher: IEEE
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» Structure and magnetism of Ge3Mn5 clusters
Abstract:
We have grown Ge3Mn5 clusters by codepositing germanium and manganese atoms on Ge(001) substrates using low temperature molecular beam epitaxy and further annealing the films at high temperature. Clusters are spherical and randomly distributed in the germanium film in epitaxial relationship with the diamond lattice. They exhibit a broad size distribution. By performing a careful x-ray diffraction analysis, we could find that 97% of Ge3Mn5 clusters have their c-axis perpendicular to the film plane while 3% exhibit in-plane c-axis. We could also show a slight in-plane distortion of the Ge3Mn5 lattice leading to a reduction of uniaxial magnetic anisotropy. These observations are well confirmed by complementary superconducting quantum interference device and electron paramagnetic resonance measurements.
Autors: Jain, A.;Jamet, M.;Barski, A.;Devillers, T.;Yu, I.-S.;Porret, C.;Bayle-Guillemaud, P.;Favre-Nicolin, V.;Gambarelli, S.;Maurel, V.;Desfonds, G.;Jacquot, J. F.;Tardif, S.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013911 - 013911-4
Publisher: IEEE
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» Structure and physical properties of GexAsySe1-x-y glasses with the same mean coordination number of 2.5
Abstract:
We have prepared and analyzed five different compositions of GexAsySe1-x-y glasses that have the same mean coordination number (MCN) of 2.5 in order to understand whether MCN or chemical composition has the dominant effect on the physical properties of the glass. Density measurements showed a maximum for the chemically stoichiometric Ge12.5As25Se62.5 sample and suggested that some rearrangement of the atoms was occurring as one atom substituted for another. The measurements of Tg, however, showed that the glasses had almost same glass transition temperature and suggested that the glass network connectivity did not change much with composition. Although Raman scattering and x-ray photoelectron spectra of the glasses indicate that the percentage of the different structural units changes with the composition, there was no evidence of the existence of structural units that could change the overall connectivity of the glass network. Therefore, we concluded that glasses with same MCN but different composition have similar glass network connectivity, and that chemical composition has only a secondary effect on the physical properties of the glasses.
Autors: Wang, R. P.;Bulla, D.;Smith, Anita;Wang, T.;Luther-Davies, Barry;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023517 - 023517-5
Publisher: IEEE
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» Structure and properties of ZrN coatings deposited by high power impulse magnetron sputtering technology
Abstract:
Monolayer ZrN coatings were deposited exclusively by the novel high power impulse magnetron sputtering (HIPIMS) technology in an industrial scale physical vapour deposition (PVD) machine (HTC-1000-4 target system). Coatings were deposited on 1 μm polished M2 high speed steel, on 304L stainless steel (SS), and on Si (100) specimens. Prior to deposition, HIPIMS plasma sustained on a zirconium (Zr) target was utilized to pretreat the specimens. Coatings were deposited at 400 °C in a mixed N2 and Ar atmosphere using 2 magnetrons in HIPIMS mode and at three different substrate bias voltages (Ubias) keeping all other process parameters constant. The thicknesses of the coatings measured by the ball cratering technique were in the ranges of 1.84, 1.96, and 2.13 μm at bias voltages of -95, -75, and -65 V, respectively, where the difference in thickness can be attributed to the resputtering effect. X-ray diffraction experiments on SS specimens revealed a dominating 111 texture for all three coatings irrespective of the bias voltage. Cross-sectional transmission electron microscopy revealed extremely dense coating structures at all bias voltages, similar to the transition zone structure (zone T) reported by Thornton. The -95 bias voltage coatings appeared extremely smooth on the top and with no dome shaped structures often associated with low ion bombardment during deposition. HIPIMS pretreatment leads to high adhesion (LC) of the coatings to the substrate. A continuous ductile perforation of the coating was observed at progressive loads greater than 65 N; however, no spallation of the coating was observed up to loads of 100 N. High values of hardness (40.4 GPa), Young’s modulus (424 GPa), and compressive st- - ress (10 GPa) were recorded for coatings deposited at -95 BV. The hardness and internal stress of the coating were found increasing with more negative bias voltages. All the coatings exhibited high dry sliding wear resistance (KC) in the range 6×10-15 m3N-1m-1. Cross-sectional transmission electron microscopy and atomic force microscopy analyses have been used to study the effect of ion bombardment obtained from HIPIMS on the structure of the coatings.
Autors: Purandare, Y. P.;Ehiasarian, A. P.;Hovsepian, P. Eh.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2011, volume: 29, issue:1, pages: 011004 - 011004-6
Publisher: IEEE
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» Structure evolution of magnetron sputtered TiO2 thin films
Abstract:
The structure evolution of TiO2 thin films deposited by rf and dc magnetron sputtering onto nonintentionally heated, floating, glass and Si (100) substrates was investigated. As the total pressure was varied from 0.15 to 4.0 Pa, corresponding to the pressure-distance product values from 10.5 to 280 Pamm, rutile, anatase, and a mixture thereof were deposited. The pressure-distance induced changes in ion energy were quantified by probing the ion energy distribution functions. The ion energy during synthesis was additionally varied by applying a substrate bias potential ranging from floating to -100 V revealing a similar phase formation characteristic. While the structure evolution of the TiO2 thin films reported in the literature exhibits a rather complex dependence on the process parameters, a simple correlation between the structure evolution and the ratio between the ion energy flux and the deposition flux was identified here. Phase pure anatase films were grown below 540 eV/Ti atom and phase pure rutile films were grown above 1000 eV/Ti atom. The here presented data suggest that the ratio between the ion energy flux and the deposition flux ratio defines the phase formation of TiO2 thin films during magnetron sputtering.
Autors: Mraz, Stanislav;Schneider, Jochen M.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023512 - 023512-6
Publisher: IEEE
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» Structure evolution of Zn cluster on graphene for ZnO nanostructure growth
Abstract:
Monte Carlo simulations are carried out for Zn cluster supported on a suspended graphene to estimate the morphological evolution of the following growth of ZnO nanostructure. The metal–metal interactions are modeled with the tight-binding many-body potential and a Lennard-Jones potential is used to describe the metal-carbon interactions. The dynamic processes of Zn cluster in the temperature field decomposing and drifting effects are visualized through the simulation. Zn atoms make one regular atomic single layer on the graphene sheet at a relatively low temperature, which would act as orderly and high density catalytic nucleation sites. In the relatively high temperature, the Zn atomic single layer falls to pieces, the orderly and low density catalytic nucleation sites are formed. It is expected from these behaviors that the buffer layer of graphene provide a sound explanation for the formation of ordered orientated ZnO nanostructure.
Autors: Guo, J. Y.;Xu, C. X.;Gu, B. X.;Sheng, F. Y.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 024307 - 024307-4
Publisher: IEEE
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» Structure, electrical properties, and depoling mechanism of BiScO3PbTiO3Pb(Zn1/3Nb2/3)O3 high-temperature piezoelectric ceramics
Abstract:
The structure, electrical properties, and depoling mechanism of the (0.95-x)BiScO3-xPbTiO3-0.05Pb(Zn1/3Nb2/3)O3 (BS-xPT-PZN, x=0.54–0.70) compositions close to the morphotropic phase boundary (MPB) have been systematically investigated as a function of PbTiO3 content (x). The phase approached from the rhombohedral toward the tetragonal phase when the PbTiO3 contents increased. The composition with high PT content exhibited normal ferroelectric behavior while it showed a diffused phase transition characteristic as PT decreased. In the vicinity of the MPB, the ceramics showed enhanced piezoelectric, electromechanical, and ferroelectric properties with piezoelectric constant d33=490 pC/N, planar electromechanical coupling factors kp=57.4%, remnant polarization Pr=40.1 μC/cm2, and coercive field Ec=28.5 kV/cm with a high transition temperature Tm∼417 °C, respectively. The thermal depoling experiments of the polarization for samples with different phase structures were investigated and the possible depoling mechanism was discussed.
Autors: Yao, Zhonghua;Liu, Hanxing;Hao, Hua;Cao, Minghe;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 014105 - 014105-8
Publisher: IEEE
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» Studentized Dynamical System for Robust Object Tracking
Abstract:
This paper describes a studentized dynamical system (SDS) for robust target tracking using a subspace representation. Dynamical systems (DS) provide a powerful framework for the probabilistic modeling of temporal sequences. Visual tracking problems are often cast as a sequential inference problem within the DS framework and a compact way to model the observation distributions (i.e., object appearances) is through probabilistic principal component analysis (PPCA). PPCA is a classic Gaussian based subspace representation method and a popular tool for appearance modeling. Although Gaussian density has theoretically nice properties, resulting in models that are always tractable, they are also severely limited in practical settings. One of the central issues in the use of PPCA for target appearance modeling is that it is very sensitive to outliers. The Gaussian density has a very light tail, while real world data with outliers exhibit heavy tails. Recently, more heavy-tailed distributions (e.g., Student's t-distribution) have been introduced to increase the robustness of the original PPCA. We propose to augment the traditional target tracking DS by adding a set of auxiliary latent variables to adjust the shape of the observation distribution. We show that by carefully choosing the probability density of these auxiliary latent variables, a more robust observation distribution can be obtained with tails heavier than Gaussian. Numerical experiments verify that the proposed SDS has a better capability to handle considerable amount of outlier noise and an improved tracking performance over DS with a Gaussian based observation model.
Autors: Gai, J.;Stevenson, R. L.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jan 2011, volume: 20, issue:1, pages: 186 - 199
Publisher: IEEE
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» Studies on vacuum deposited p-ZnTe/n-CdTe heterojunction diodes
Abstract:
 Research highlights: ? We have fabricated p-ZnTe/n-CdTe heterojunction diode by vacuum deposition. ? We have determined the dominant conduction mechanisms in the heterojunction. ? Barrier height, width of the depletion region have been determined. ? A band diagram of the heterojunction has been drawn based on Anderson's Model.

Autors: The present paper reports the fabrication and detailed electrical characterization of p-ZnTe/n-CdTe heterojunction diodes prepared by vacuum deposition method. The possible conduction mechanisms of the heterojunction diode were determined by analyzin
Appeared in: Solid-State Electronics
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Study of Carrier Mobility of Low-Energy High-Dose Ion Implantations
Abstract:
New carrier drift mobility data for boron-, phosphorus-, and arsenic-doped Si in a low-energy high-dose implant regime are measured and studied using a continuous anodic oxidation technique/differential Hall effect technique. The data show that, when the doping concentration is , both the hole and electron mobility values are lower than the conventional model predictions, and the electron mobility of the As-doped Si is lower than that of the P-doped ones. The data also show that, when the doping concentration is , the hole mobility in the B-doped Si and the electron mobility in the P-doped Si are almost equal and reach as low as , and the electron mobility of the As-doped Si is the lowest and reaches . These mobility data are much lower than the conventional model predictions and are also lower than the previously published data. For the ULSI device and circuit analyses, simulations, and designs, these new mobility data need to be taken into consideration.
Autors: Qin, S.;Prussin, S. A.;Reyes, J.;Hu, Y. J.;McTeer, A.;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2011, volume: 39, issue:1, pages: 587 - 592
Publisher: IEEE
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» Study of Different Architectures of Fault-Tolerant Actuator Using a Two-Channel PM Motor
Abstract:
In the context of more electric aircraft, the use of electric actuators instead of hydraulic ones is one of the main topics of research and development in electrical engineering. A high level of reliability, the redundancy, and the compactness are required for aircraft electrical actuators. For achieving these purposes, a classical solution consists in using two identical actuators motorized by one permanent magnet (PM) motor supplied by a voltage source inverter (VSI). In this paper, a solution based on the use of only one fault-tolerant actuator performed by a two-star connected-winding (two-channel) PM motor supplied by two pulsewidth modulated VSIs is proposed. The design of the PM motor can be achieved in two different ways, which are proposed and studied in this paper. The authors focus this paper on the comparison between the two winding architectures and compare the two motors in terms of the short-circuit current and magnetic decoupling of the two windings. Both simulation and experimental results are given and discussed.
Autors: Vaseghi, B.;Takorabet, N.;Caron, J. P.;Nahid-Mobarakeh, B.;Meibody-Tabar, F.;Humbert, G.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2011, volume: 47, issue:1, pages: 47 - 54
Publisher: IEEE
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» Study of field emission, electrical transport, and their correlation of individual single CuO nanowires
Abstract:
We report our recent findings from the study of the field emission, electrical transport, and their correlation of individual single CuO nanowires grown by thermal oxidation. Typical Fowler–Nordheim (FN) plot of a single CuO nanowire exhibits an upward bending behavior with increasing applied electric field: a rare phenomenon of field emission from nanowires. The electrical transport measurement has shown that the CuO nanowire has a typical conductivity of 7.8×10-4 (Ω cm)-1. X-ray photoelectron spectroscopy study has given the energy band gap of 1.2 eV with Fermi energy level close to the top of valence band, confirming that the CuO nanowire is p-type. The upward bending FN plot can be explained using a field emission model of p-type semiconductor.
Autors: Shao, PengRui;Deng, ShaoZhi;Chen, Jun;Chen, Jian;Xu, NingSheng;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023710 - 023710-6
Publisher: IEEE
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» Study on an Audible Noise Reduction Measure for Filter Capacitors Based on Compressible Space Absorber
Abstract:
Filter capacitors in an HVDC converter station produce audible noise, which can be as loud as that of converter transformers and, therefore, needs to be reduced. Compressible space component (CSC) absorbers can be used to reduce the audible noise due to their broadband frequency and outstanding performance. In this paper, a mechanical model of a CSC absorber is proposed as an audible noise reduction measure for the filter capacitor in the HVDC converter station and then three CSC absorbers with different gas volumes are designed and installed at the bottoms of capacitors, respectively. Audible noise experiments of the filter capacitors with different CSC absorbers are performed and the experimental results are compared with those of a regular filter capacitor. Results indicate that the CSC absorber is a broadband absorber and is effective to reduce audible noise of the filter capacitors.
Autors: Peng, W.;Shengchang, J.;Yanming, L.;Tao, C.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jan 2011, volume: 26, issue:1, pages: 438 - 445
Publisher: IEEE
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» Study on delamination mechanism of SU-8 micropillars on a Si-substrate under bend loading by Weibull analysis
Abstract:
Interfacial delamination mechanism between SU-8 micropillars with the widely change of aspect ratio and Si substrates was studied using Weibull distribution. Micropillars were fabricated by lithography on the substrate and delaminated from the substrate under bend loading. Delamination for aspect ratio of 1.4 and 2.2 with almost the same ?max indicates mode I fracture at interface and then shear stress increased as aspect ratio decreases. m value tends to become larger with distance from the complex stress area of ?max.
Autors: Toshikazu, Tasaki , Tso-Fu Mark, Chang , Chiemi, Ishiyama , Masato, Sone
Appeared in: Microelectronic Engineering
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Studying bacterial adhesion forces: Staphylococcus aureus on elastic poly(dimethyl)siloxane substrates
Abstract:
To investigate the forces acting between Staphylococcus aureus and its surrounding environment we have designed and fabricated a poly(dimethyl)siloxane substrate with microstructured pillars. The deflection of those pillars due to the adhesion of S. aureus serves as a means for force estimation and is measured in a scanning electron microscope after fixation of the incubated substrates. Our results suggest that the forces exerted by S. aureus, as a member of the class of prokaryotic cells, are higher than those typically observed for eukaryotic cells.
Autors: Peter, Nill , Nadine, Goehring , Ronny, Loeffler , Andreas, Peschel , Dieter P., Kern
Appeared in: Microelectronic Engineering
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Style and Technology of IAS Technical Papers [History]
Abstract:
Thousands of conference papers have been published by the IEEE Industry Applications Society (IAS) since its formation in 1965. These IAS papers and contemporary industrial reports and papers have significantly changed in appearance over the years because of the changes in the technology of preparing papers.
Autors: Brauer, J.R.;
Appeared in: IEEE Industry Applications Magazine
Publication date: Jan 2011, volume: 17, issue:1, pages: 8 - 10
Publisher: IEEE
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» Sub-Hexagonal Phase Correlation for Motion Estimation
Abstract:
We present a novel frequency-domain motion estimation technique, which operates on hexagonal images and employs the hexagonal Fourier transform. Our method involves image sampling on a hexagonal lattice followed by a normalised hexagonal cross-correlation in the frequency domain. The term subpixel (or subcell) is defined on a hexagonal grid in order to achieve floating point registration. Experiments using both artificially induced motion and actual motion demonstrate that the proposed method outperforms the state-of-the-art in frequency-domain motion estimation operating on a square lattice, in the shape of phase correlation, in terms of subpixel accuracy for a range of test material and motion scenarios.
Autors: Argyriou, V.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jan 2011, volume: 20, issue:1, pages: 110 - 120
Publisher: IEEE
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» Sublinear Capacity Scaling Laws for Sparse MIMO Channels
Abstract:
Recent attention on performance analysis of single-user multiple-input–multiple-output (MIMO) systems has been on understanding the impact of the spatial correlation model on ergodic capacity. In most of these works, it is assumed that the statistical degrees of freedom (DoF) in the channel can be captured by decomposing it along a suitable eigenbasis and that the transmitter has perfect knowledge of the statistical DoF. With an increased interest in large-antenna systems in state-of-the-art technologies, these implicit channel modeling assumptions in the literature have to be revisited. In particular, multiantenna measurements have showed that large-antenna systems are sparse where only a few DoF are dominant enough to contribute towards capacity. Thus, in this work, it is assumed that the transmitter can only afford to learn the dominant statistical DoF in the channel. The focus is on understanding ergodic capacity scaling laws in sparse channels. Unlike classical results, where linear capacity scaling is implicit, sparsity of MIMO channels coupled with a knowledge of only the dominant DoF is shown to result in a new paradigm of sublinear capacity scaling that is consistent with experimental results and physical arguments. It is also shown that uniform-power signaling over all the antenna dimensions is wasteful and could result in a significant penalty over optimally adapting the antenna spacings in response to the sparsity level of the channel and transmit .
Autors: Raghavan, V.;Sayeed, A. M.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jan 2011, volume: 57, issue:1, pages: 345 - 364
Publisher: IEEE
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» Subspace-Based Adaptive Method for Estimating Direction-of-Arrival With Luenberger Observer
Abstract:
In this paper, we propose a computationally simple and efficient subspace-based adaptive method for estimating directions-of-arrival (AMEND) for multiple coherent narrowband signals impinging on a uniform linear array (ULA), where the previously proposed QR-based method is modified for the number determination, a new recursive least-squares (RLS) algorithm is proposed for null space updating, and a dynamic model and the Luenberger state observer are employed to solve the estimate association of directions automatically. The statistical performance of the RLS algorithm in stationary environment is analyzed in the mean and mean-squares senses, and the mean-square-error (MSE) and mean-square derivation (MSD) learning curves are derived explicitly. Furthermore, an analytical study of the RLS algorithm is carried out to quantitatively compare the performance between the RLS and least-mean-square (LMS) algorithms in the steady-state. The theoretical analyses and effectiveness of the proposed RLS algorithm are substantiated through numerical examples.
Autors: Xin, J.;Zheng, N.;Sano, A.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jan 2011, volume: 59, issue:1, pages: 145 - 159
Publisher: IEEE
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» Substation Maintenance Strategy Adaptation for Life-Cycle Cost Reduction Using Genetic Algorithm
Abstract:
The choice of the right maintenance strategy is an important but also difficult topic for every energy utility. The difficulty consists in the huge number of interacting cost parameters. The present paper shows how from the biology well known process is adapted as an optimization algorithm in order to handle the parameter diversity. Outgoing from the definition of Life Cycle Cost and a method for substation reliability calculation the main idea of genetic algorithm and its application for Life Cycle Cost optimization is presented. Closing a case study shows the suitability of the algorithm.
Autors: Hinow, M.;Mevissen, M.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jan 2011, volume: 26, issue:1, pages: 197 - 204
Publisher: IEEE
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» Substrate Integrated Waveguide Loaded by Complementary Split-Ring Resonators for Miniaturized Diplexer Design
Abstract:
A novel high-performance planar diplexer is developed based on the substrate integrated waveguide (SIW) with complementary split-ring resonators (CSRRs) etched on the waveguide surface. The proposed diplexer is operated below the characteristic cutoff frequency of the waveguide. The filtering response of the SIW-CSRR combined structure is investigated first. The diplexer is then implemented based on two cascaded two-pole bandpass filters. Equivalent circuit, simulated results and experimental verification are all provided. This diplexer shows advantages in terms of the compact size, low loss, high isolation, easy fabrication and integration with other circuits.
Autors: Dong, Y.;Itoh, T.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jan 2011, volume: 21, issue:1, pages: 10 - 12
Publisher: IEEE
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» Substrate orientation effects on the nucleation and growth of the Mn+1AXn phase Ti2AlC
Abstract:
The Mn+1AXn (MAX) phases are ternary compounds comprising alternating layers of a transition metal carbide or nitride and a third “A-group” element. The effect of substrate orientation on the growth of Ti2AlC MAX phase films was investigated by studying pulsed cathodic arc deposited samples grown on sapphire cut along the (0001), (1010), and (1102) crystallographic planes. Characterization of these samples was by x-ray diffraction, atomic force microscopy, and cross-sectional transmission electron microscopy. On the (1010) substrate, tilted (1018) growth of Ti2AlC was found, such that the TiC octahedra of the MAX phase structure have the same orientation as a spontaneously formed epitaxial TiC sublayer, preserving the typical TiCTi2AlC epitaxial relationship and confirming the importance of this relationship in determining MAX phase film orientation. An additional component of Ti2AlC with tilted fiber texture was observed in this sample; tilted fiber texture, or axiotaxy, has not previously been seen in MAX phase films.
Autors: Tucker, Mark D.;Persson, Per O. A.;Guenette, Mathew C.;Rosen, Johanna;Bilek, Marcela M. M.;McKenzie, David R.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 014903 - 014903-6
Publisher: IEEE
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» Sufficient Statistics as a Generalization of Binning in Spectral X-ray Imaging
Abstract:
It is well known that the energy dependence of X-ray attenuation can be used to characterize materials. Yet, even with energy discriminating photon counting X-ray detectors, it is still unclear how to best form energy dependent measurements for spectral imaging. Common ideas include binning photon counts based on their energies and detectors with both photon counting and energy integrating electronics. These approaches can be generalized to energy weighted measurements, which we prove can form a sufficient statistic for spectral X-ray imaging if the weights used, which we term -weights, are basis attenuation functions that can also be used for material decomposition. To study the performance of these different methods, we evaluate the Cramér-Rao lower bound (CRLB) of material estimates in the presence of quantum noise. We found that the choice of binning and weighting schemes can greatly affect the performance of material decomposition. Even with optimized thresholds, binning condenses information but incurs penalties to decomposition precision and is not robust to changes in the source spectrum or object size, although this can be mitigated by adding more bins or removing photons of certain energies from the spectrum. On the other hand, because -weighted measurements form a sufficient statistic for spectral imaging, the CRLB of the material decomposition estimates is identical to the quantum noise limited performance of a system with complete energy information of all photons. Finally, we show that -weights lead to increased conspicuity over other methods in a simulated calcium contrast experiment.
Autors: Wang, A. S.;Pelc, N. J.;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2011, volume: 30, issue:1, pages: 84 - 93
Publisher: IEEE
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» Super-Resolution Method for Face Recognition Using Nonlinear Mappings on Coherent Features
Abstract:
Low-resolution (LR) of face images significantly decreases the performance of face recognition. To address this problem, we present a super-resolution method that uses nonlinear mappings to infer coherent features that favor higher recognition of the nearest neighbor (NN) classifiers for recognition of single LR face image. Canonical correlation analysis is applied to establish the coherent subspaces between the principal component analysis (PCA) based features of high-resolution (HR) and LR face images. Then, a nonlinear mapping between HR/LR features can be built by radial basis functions (RBFs) with lower regression errors in the coherent feature space than in the PCA feature space. Thus, we can compute super-resolved coherent features corresponding to an input LR image according to the trained RBF model efficiently and accurately. And, face identity can be obtained by feeding these super-resolved features to a simple NN classifier. Extensive experiments on the Facial Recognition Technology, University of Manchester Institute of Science and Technology, and Olivetti Research Laboratory databases show that the proposed method outperforms the state-of-the-art face recognition algorithms for single LR image in terms of both recognition rate and robustness to facial variations of pose and expression.
Autors: Huang, H.;He, H.;
Appeared in: IEEE Transactions on Neural Networks
Publication date: Jan 2011, volume: 22, issue:1, pages: 121 - 130
Publisher: IEEE
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» Superconductivity of Ultra-fine Tungsten Nanowires Grown by Focused-ion-beam Direct-writing
Abstract:
The electrical properties of lateral ultrafine tungsten nanowires, which were grown by focused-ion-beam-induced deposition with 1 pA ion beam current, were investigated. Temperature-dependent electrical measurements show that the wires are conducting and have a superconducting transition with a transition temperature (Tc) about 5.1 K. Resistance vs temperature measurements reveal that, with decreasing cross-sectional area, the wires display an increasingly broad superconducting transition. A residual resistive tail extending down to the low-temperature region is found only for the thinnest tungsten nanowire, which is 10 nm thick and 19 nm wide. The logarithm of the residual resistance of this wire appears as...
Autors: Wuxia, Li , J.C., Fenton , Changzhi, Gu , P.A., Warburton
Appeared in: Microelectronic Engineering
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Superhard B2C2N2 compounds from first-principles calculations
Abstract:
The structural, electronic, and mechanical properties as well as phase transitions under hydrostatic pressures have been investigated for six possible B2C2N2 structures, which are deduced from 3C–SiC unit cell. Our calculation results show that B2C2N2-1 with the maximum numbers of C–C and B–N bonds has the lowest total energy. The B2C2N2-1 is a large gap semiconductor with indirect band gap of 4.10 eV. The calculated elastic stiffness constants and phonon spectrum have confirmed its mechanical and dynamical stability. The calculated bulk and shear moduli, and Vickers hardness of B2C2N2-1 indicate that it is one potential superhard material with hardness larger that of cubic boron nitride. The pressure-induced structural transition between its low and high dense phases have shown that B2C2N2-1 could be synthesized using high-temperature and high-pressure method.
Autors: Xiaoguang, Luo;Luyan, Li;Weihua, Wang;Yongjun, Tian;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023516 - 023516-4
Publisher: IEEE
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» Supervisory Control of Uncertain Linear Time-Varying Systems
Abstract:
We consider the problem of adaptively stabilizing linear plants with unknown time-varying parameters in the presence of noise, disturbances, and unmodeled dynamics using the supervisory control framework, which employs multiple candidate controllers and an estimator based switching logic to select the active controller at every instant of time. Time-varying uncertain linear plants can be stabilized by supervisory control, provided that the plant's parameter varies slowly enough in terms of mixed dwell-time switching and average dwell-time switching, the noise and disturbances are bounded and small enough in terms of L-infinity norms, and the unmodeled dynamics are small enough in the input-to-state stability sense. This work extends previously reported works on supervisory control of linear time-invariant systems with constant unknown parameters to the case of linear time-varying uncertain systems. A numerical example is included, and limitations of the approach are discussed.
Autors: Vu, L.;Liberzon, D.;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Jan 2011, volume: 56, issue:1, pages: 27 - 42
Publisher: IEEE
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» Support system for efficient dosage of orchard and vineyard spraying products
Abstract:
 Research highlights: ? Label dose rates do not fully support the efficient use of pesticide for orchard and vineyard spraying. ? This research establishes a system to improve support. ? The system uses a dose adjustment model and a standard target structure. ? The system is evaluated using spray trials measurements from previous publications.

Autors: This paper establishes a system to support the dose evaluation part of the pesticide registration process so that growers can make more efficient use of different spraying products across a broad range of European orchards and vineyards. The system c
Appeared in: Computers and Electronics in Agriculture
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Suppression of donor-vacancy clusters in germanium by concurrent annealing and irradiation
Abstract:
Diffusion of phosphorous and arsenic in germanium under in situ proton irradiation has been performed and analyzed with secondary ion mass spectrometry. Dopant profiles corresponding to proton-exposed regions exhibit a higher penetration depth and more pronounced box shape than profiles of nonexposed regions. Continuum theoretical simulations reveal that diffusion under irradiation is much less affected by inactive donor-vacancy clusters than diffusion under annealing only. The suppression of donor-vacancy clusters is caused by interstitials in supersaturation and vacancy concentrations close to thermal equilibrium. Concurrent annealing and irradiation have the potential to attain high active doping levels in Ge.
Autors: Schneider, S.;Bracht, H.;
Appeared in: Applied Physics Letters
Publication date: Jan 2011, volume: 98, issue:1, pages: 014101 - 014101-3
Publisher: IEEE
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» Surface charge measurement in surface dielectric barrier discharge by laser polarimetry
Abstract:
Measurements of surface charge in a surface dielectric barrier discharge driven in atmospheric air were successfully demonstrated by a laser polarimetry. AC voltage at a frequency of 2 kHz generated the discharge between an exposed electrode and the dielectric barrier over a buried electrode. Although the discharge behaviors varied depending on the polarity of the exposed electrode, there were no differences in the tendency and amplitude of the surface charge accumulation except the polarity. With higher applied voltage, the amount of surface charge became larger and the charge was distributed farther from the exposed electrode.
Autors: N., Takeuchi , T., Hamasaki , K., Yasuoka , T., Sakurai
Appeared in: Journal of Electrostatics
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Surface effects on axial buckling of nonuniform nanowires using non-local elasticity theory
Abstract:
The non-local elasticity theory is used to study the buckling behaviour of a nonuniform nanowire with consideration of surface effects. An analytical expression for the calculation of critical buckling load of the nanowire is obtained. In addition, the Rayleigh??Ritz method is used to analyse the influences of surface and nanolocal effects on the critical buckling load of the nonuniform nanowire. Results show that the surface effects are more significant for a slender nanowire with a higher diameter ratio. The critical buckling load increases with decreasing non-local parameter.
Autors: Haw-Long Lee;Win-Jin Chang;
Appeared in: IET Micro & Nano Letters
Publication date: Jan 2011, volume: 6, issue:1, pages: 19 - 21
Publisher: IEEE
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» Surface interactions of SO2 and passivation chemistry during etching of Si and SiO2 in SF6/O2 plasmas
Abstract:
A variety of materials can be etched in SF6/O2 plasmas. Here, the fate of SO2 at Si and SiO2 surfaces during etching in SF6/O2 plasmas has been explored using the imaging of radicals interacting with surfaces method. The scattering of SO2 at Si and SiO2 surfaces was measured as a function of both the applied rf power and O2 addition to the plasma. For both surfaces, the surface scattering coefficient (S) of SO2 during etching is near unity and is largely unaffected by changing plasma parameters such as power and O2 addition. Notably the etch rate of Si increases monotonically with power, whereas the etch rate of SiO2 appears insensitive to changes in plasma conditions. As a result, the etch selectivity closely follows the trends of the Si etch rate. Etch rates are compared to other fluorine-containing plasma systems such as NF3/O2 and C2F6/O2. Using mass spectral data and optical emission spectra to characterize the gas phase species combined with compositional analysis from x-ray photoelectron spectroscopy data, the formation and roles of SO2 in Si and SiO2 etching are discussed and correlated with etch rate and other gas phase species such as F, O, and SxOyFz.
Autors: Stillahn, Joshua M.;Zhang, Jianming;Fisher, Ellen R.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2011, volume: 29, issue:1, pages: 011014 - 011014-10
Publisher: IEEE
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» Surface modification of a ferroelectric polymer insulator for low-voltage readable nonvolatile memory in an organic field-effect transistor
Abstract:
We demonstrate that the sequential surface modification of a ferroelectric polymer insulator plays an essential role in both the enhancement of the carrier mobility and the shift in the turn-on voltage (Von) in an organic ferroelectric field-effect transistor (FeFET) for nonvolatile memory. The surface of a ferroelectric polymer insulator, poly(vinylidene fluoride-trifluoroethylene), is physicochemically modified by the successive treatments of ultraviolet-ozone (UVO) and CF4 plasma to understand how the surface morphology and the hydrophobicity affect the grain size, the mobility, and Von in the FeFET. In a pentacene-based FeFET, the CF4 plasma irradiation leads to the mobility enhancement by a factor of about 5 as well as the shift in Von toward a positive voltage direction while the UVO treatment results in only the shift in Von toward a negative voltage direction. It is found that the sequence of the two successive treatments is critical for tailoring interfacial interactions between the ferroelectric polymer insulator and the pentacene layer. The underlying mechanism for the mobility enhancement and the shift in Von is described in terms of the surface morphology and the nature of the built-in electric field.
Autors: Kim, Won-Ho;Bae, Jin-Hyuk;Kim, Min-Hoi;Keum, Chang-Min;Park, Jaehoon;Lee, Sin-Doo;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 024508 - 024508-6
Publisher: IEEE
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» Surface-Passivation Effects on the Performance of 4H-SiC BJTs
Abstract:
In this brief, the electrical performance in terms of maximum current gain and breakdown voltage is compared experimentally and by device simulation for 4H-SiC BJTs passivated with different surface-passivation layers. Variation in bipolar junction transistor (BJT) performance has been correlated to densities of interface traps and fixed oxide charge, as evaluated through MOS capacitors. Six different methods were used to fabricate surface passivation on BJT samples from the same wafer. The highest current gain was obtained for plasma-deposited which was annealed in ambient at 1100 for 3 h. Variations in breakdown voltage for different surface passivations were also found, and this was attributed to differences in fixed oxide charge that can affect the optimum dose of the high-voltage junction-termination extension (JTE). The dependence of breakdown voltage on the dose was also evaluated through nonimplanted BJTs with etched JTE.
Autors: Ghandi, R.;Buono, B.;Domeij, M.;Esteve, R.;Schoner, A.;Han, J.;Dimitrijev, S.;Reshanov, S. A.;Zetterling, C.-M.;Ostling, M.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2011, volume: 58, issue:1, pages: 259 - 265
Publisher: IEEE
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» Surveying and comparing simultaneous sparse approximation (or group-lasso) algorithms
Abstract:
 Abstract: In this paper, we survey and compare different algorithms that,given an overcomplete dictionary of elementary functions, solve the problemof simultaneous sparse signal approximation,with common sparsity profile induced by a lp-lq mixed-norm.Such a problem is also known in the statisticallearning community as the group lasso problem.We have gathered and detailed different algorithmic results concerningthese two equivalent approximation problems. We have also enriched thediscussion by providing relations between severalalgorithms. Experimental comparisons of the detailed algorithms have also been carriedout. The main lesson learned from these experimentsis that depending on the performance measure,greedy approaches and iterative reweighted algorithms are the most efficient algorithms...
Autors: Alain, Rakotomamonjy
Appeared in: Signal Processing
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» SWATS: Wireless sensor networks for steamflood and waterflood pipeline monitoring
Abstract:
State-of-the-art anomaly detection systems deployed in oilfields are expensive, not scalable to a large number of sensors, require manual operation, and provide data with a long delay. To overcome these problems, we design a wireless sensor network system that detects, identifies, and localizes major anomalies such as blockage and leakage that arise in steamflood and waterflood pipelines in oilfields. A sensor network consists of small, inexpensive nodes equipped with embedded processors and wireless communication, which enables flexible deployment and close observation of phenomena without human intervention. Our sensornetwork- based system, Steamflood and Waterflood Tracking System (SWATS), aims to allow continuous monitoring of the steamflood and waterflood systems with low cost, short delay, and fine-granularity coverage while providing high accuracy and reliability. The anomaly detection and identification is challenging because of the inherent inaccuracy and unreliability of sensors and the transient characteristics of the flows. Moreover, observation by a single node cannot capture the topological effects on the transient characteristics of steam and water fluid to disambiguate similar problems and false alarms. We address these hurdles by utilizing multimodal sensing and multisensor collaboration, and exploiting temporal and spatial patterns of the sensed phenomena.
Autors: Yoon, S.;Ye, W.;Heidemann, J.;Littlefield, B.;Shahabi, C.;
Appeared in: IEEE Network
Publication date: Jan 2011, volume: 25, issue:1, pages: 50 - 56
Publisher: IEEE
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» Switchable bandpass filter with two-state frequency responses
Abstract:
A novel switchable bandpass filter with two-state frequency responses is presented, where dual-band bandpass and single bandpass characteristics can be conveniently switched by turning pin diodes on and off. The switchability results from the effect of different working modes. The filter can work as a dual-band bandpass filter obtaining two centre frequencies, 1.8 and 3.5 GHz, which could be appropriately used for GSM and WiMax systems. In the meantime, it also can operate only at 3.5 GHz, rejecting signal at 1.8 GHz. The proposed filter consists of two dual-mode resonators, using pin diodes to switch the frequency responses. An experiment was carried out to validate the design concept, and the measured results agree well with simulated results.
Autors: Lui, B.;Wei, F.;Shi, X.;
Appeared in: Electronics Letters
Publication date: Jan 2011, volume: 47, issue:1, pages: 40 - 41
Publisher: IEEE
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» Switching frequency response characteristics of a low cost wireless power driving and controlling system for electrically tunable liquid crystal microlenses
Abstract:
The essential switching frequency response characteristics of a low cost wireless power driving and controlling system for electrically tunable liquid crystal microlenses (ETLCMs) are obtained. The wireless power system is mainly composed of two coils with different radius and winding as well as a power metal–oxide–semiconductor field effect transistor switch. The voltage response in the small coil, which is connected directly with ETLCMs, is measured and analyzed under the condition of changing some key parameters of the coil system, such as the width of switching frequency region and the duty-cycle of the switching signal ranging from 20% to 80% in intervals of 20%. Through extending the switching frequency range to a few hundreds of kilohertz, an attractive property of only modulating switching frequency to tune precisely the rms voltage in the small coil for ETLCMs is presented. Some interesting phenomena in high frequency regions, for instance, the rms voltage being stable or slightly changed as the frequency, the voltage response cutoff or disappearance after the frequency surpassing a threshold value, and then regeneration after lowering the frequency to lower frequency point than that of generating voltage response cutoff during increasing frequency, are also discovered.
Autors: Zhang, Xinyu;Li, Hui;Liu, Kan;Luo, Jun;Xie, Changsheng;Ji, An;Zhang, Tianxu;
Appeared in: Review of Scientific Instruments
Publication date: Jan 2011, volume: 82, issue:1, pages: 014701 - 014701-7
Publisher: IEEE
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» Switching Function Model-Based Fast-Diagnostic Method of Open-Switch Faults in Inverters Without Sensors
Abstract:
A novel fast-diagnostic method for open-switch faults in inverters without sensors is proposed to improve the reliability of power electronic system in this paper. The presented method is achieved by analysis of switching function model of the inverter under both healthy and faulty conditions. Due to the different voltages endured by each power switch under healthy condition from open-switch faults in some cases, open-circuit faults can be detected by sensing the collector–emitter voltages of the lower power switches in each leg. The diagnostic scheme employs the simple hardware circuit to obtain indirectly the voltages of lower power switches and to get rid of high cost and complexity as a result of sensors. Also, this method minimizes the detection time and is available for the inverter faults in the systems with open-loop or closed-loop current control strategies. To ensure the effectiveness and reliability of the proposed diagnostic method, the rising-edge delays for switching signals are used to avoid misdiagnostic results because of the ON–OFF processes of power switches, and the delay durations are determined considering various factors. Simulation and experimental results validate the proposed scheme for detecting switch and leg open-circuit faults.
Autors: An, Q.-T.;Sun, L.-Z.;Zhao, K.;Sun, L.;
Appeared in: IEEE Transactions on Power Electronics
Publication date: Jan 2011, volume: 26, issue:1, pages: 119 - 126
Publisher: IEEE
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» Symbol Error Probability of QAM with MRC Diversity in Two-Wave with Diffuse Power Fading Channels
Abstract:
In the context of two-wave with diffuse power (TWDP) fading scenarios, this letter analyzes the average symbol error probability (SEP) of rectangular quadrature amplitude modulation (QAM) for single- and multi-channel receptions. Specifically, novel exact expressions are derived for the average SEP in nondiversity and maximal-ratio combining (MRC) schemes. Our derived SEP results apply to general operating scenarios with distinct TWDP fading parameters and arbitrary number of diversity branches.
Autors: Lu, Yao;Yang, Nan;
Appeared in: IEEE Communications Letters
Publication date: Jan 2011, volume: 15, issue:1, pages: 10 - 12
Publisher: IEEE
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» Symbol Error Probability of Two-Way Amplify-and-Forward Relaying
Abstract:
The overall outage probability (OOP) and symbol error probability (SEP) of a two-way amplify-and-forward (AF) relaying system are investigated. Tight closed-form expressions for the OOP and average SEP are derived for single-relay two-way AF systems. Further, in the case of multiple-relay two-way relaying, a tight closed-form expression for the OOP and an asymptotic approximation to the average SEP are obtained, respectively. Using these expressions, one can evaluate the outage and SEP performance of a two-way relaying system easily and fast.
Autors: Guo, Hui;Ge, Jianhua;Ding, Haiyang;
Appeared in: IEEE Communications Letters
Publication date: Jan 2011, volume: 15, issue:1, pages: 22 - 24
Publisher: IEEE
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» Synchrotron photoemission studies on reconstructed strained surfaces
Abstract:
Recently, based on scanning tunneling microscopy studies of the reconstructed Si(5 5 12)-2×1 surface, it has been suggested that its unit cell simply consists of four kinds of one-dimensional (1D) structures: π-bonded (π) chain, honeycomb (H) chain, tetramer (T) row, and dimer-adatom (D-A) row. In the present study, by angle-resolved ultraviolet photoelectron spectroscopy, it has been found out that the Si(5 5 12)-2×1 surface has two kinds of surface states, one with a negligible dispersion originating from row structures (T/D-A) and the other with a strong dispersion originating from chain structures (π/H). Also, the Si 2p core-level spectrum shows at least two kinds of surface components, one with 0.23 eV higher binding energy originating from upward-relaxed surface atoms and subsurface atoms, and the other with 0.52 eV lower binding energy originating from downward-relaxed surface atoms. It can be realized that these spectroscopic results quantitively match with the structural model of Si(5 5 12)-2×1 having four kinds of 1D structures.
Autors: Kim, Hidong;Li, Huiting;Duvjir, Ganbat;Seo, Jae M.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2011, volume: 29, issue:1, pages: 011003 - 011003-5
Publisher: IEEE
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» Synthesis and characterization of superfine pure tetragonal nanocrystalline sulfated zirconia powder by a non-alkoxide sol-gel route
Abstract:
Nanocrystalline sulfated zirconia powder was prepared by a non-alkoxide sol-gel route using acidic condition (pH 1-2). The samples had superfine crystallites and pure tetragonal phase at 700°C. Zr(acac)4 was used as zirconium precursor due to a better retention of sulfate species and H2SO4 0.5M was used as sulfating agent. Fourier transform infrared (FT-IR) spectra have shown Zr-O-Zr and sulfate bonds. Crystal phase and crystallite size have been determined by X-ray Diffraction (XRD) analysis. Besides, the morphology of the samples has been investigated by field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The optical properties of the samples...
Autors: Felora, Heshmatpour , Reza Babadi, Aghakhanpour
Appeared in: Advanced Powder Technology
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Synthesis of multifractional Gaussian noises based on variable-order fractional operators
Abstract:
In this paper, a synthesis method, which is based on variable-order fractional operators, for multifractional Gaussian noises (mGn) is proposed by studying the relationship of white Gaussian noise (wGn), mGn, and multifractional Brownian motion (mBm). Furthermore, a synthesis method for multifractional ?-stable processes, the generalization of mGn, is proposed in order to more accurately characterize the processes with local scaling characteristics and heavy tailed distributions. Synthetic examples of mGn and multifractional ?-stable noises are provided for illustration.
Autors: Hu, Sheng , Hongguang, Sun , YangQuan, Chen , TianShuang, Qiu
Appeared in: Signal Processing
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» Synthesizing metamaterials with angularly independent effective medium properties based on an anisotropic parameter retrieval technique coupled with a genetic algorithm
Abstract:
In this paper, we present a method to retrieve the effective electromagnetic parameters of a slab of anisotropic metamaterial from reflection and transmission coefficients (or scattering parameters). In this retrieval method, calculated or measured scattering parameters are employed for plane waves incident obliquely on a metamaterial slab at different angles. Useful analytical expressions are derived for extracting the homogeneous anisotropic medium parameters of a metamaterial. To validate the method, the effective permittivity and permeability tensor parameters for a composite split-ring resonator-wire array are retrieved and shown to be consistent with observations previously reported in the literature. This retrieval method is further incorporated into a genetic algorithm (GA) to synthesize an infrared zero-index-metamaterial with a wide field-of-view, demonstrating the utility of the new design approach. The anisotropic parameter retrieval algorithm, when combined with a robust optimizer such as GA, can provide a powerful design tool for exploiting the anisotropic properties in metamaterials to achieve specific angle dependant or independent responses.
Autors: Jiang, Zhi Hao;Bossard, Jeremy A.;Wang, Xiande;Werner, Douglas H.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013515 - 013515-11
Publisher: IEEE
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» Systematic Coupling of Multiple Magnetic Field Systems and Circuits Using Finite Element and Modified Nodal Analyses
Abstract:
Existing circuit-field coupling schemes can deal with a single magnetic field model connected to an external circuit. However, modern electrical systems are a complex interconnection of multiple magnetic devices, which opens up the question of how to consider multiple interacting field models. In this paper, we propose a scheme based on the finite element and modified nodal analyses, to solve the problem of coupling multiple magnetic field systems with circuit networks. The proposed methodology is systematic since each element within the electrically connected problem has a building block, which is easily inserted into the global system of equations. This applies to any magnetic field system, where massive and filamentary conductors are equally accommodated. Hence, each electrical network component can be modeled with any desired level of detail: as a magnetic system (distributed parameter model) or as a circuit (lumped parameter model). To show the flexibility and power of the proposed methodology, the finite-element models of a three-phase induction motor and a transformer are electrically interconnected through circuits that represent an infinite bus bar and a short transmission line.
Autors: Escarela-Perez, R.;Melgoza, E.;Alvarez-Ramirez, J.;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jan 2011, volume: 47, issue:1, pages: 207 - 213
Publisher: IEEE
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» Systematic study of sensitized LaF3:Eu3+ nanoparticles
Abstract:
We have performed a systematic structural, vibrational, and optical study of LaF3:Eu3+ nanoparticles capped with oleic acid (OA) or OA and sensitized with thenoyltrifluoroacetone (TTA). The average nanoparticle size was around 11 nm for all Eu3+ concentrations. A shift in the energy of the Raman active modes is observed with increasing Eu3+ concentration that can be accounted for by a decrease in the unit cell volume. Sensitization by TTA was observed and resulted in an 18 000% increase in the photoluminescence (PL) intensity for TTA/OA capped LaF3:Eu3+ nanoparticles when compared with OA capped LaF3:Eu3+ nanoparticles. There is also a large increase in the 5D07F2 PL intensity, when normalized to the 5D07F1 PL magnetic dipole transition intensity, for TTA/OA capped nanoparticles. The changes in the PL intensities, PL lifetimes, Judd–Ofelt parameters, stimulated emission cross sections, and quantum efficiencies, for OA and TTA/OA capped LaF3:Eu3+ nanoparticles with increasing Eu3+ concentration can be accounted for by a model that separates the Eu3+ sites into sites near the surface and Eu3+ sites in the core as well as nonradiative recombination sites near the surface. The large increase in PL intensity due to TTA sensitization means that TTA capped LaF3:Eu3+ can potentially be used for applications that include optical amplification.
Autors: Janssens, S.;Williams, G. V. M.;Clarke, D.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023506 - 023506-9
Publisher: IEEE
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» TDDB and Pulse-Breakdown Studies of Si-Rich Antifuses and Antifuse-Based ROMs
Abstract:
Antifuses are electronic devices that can be irreversibly converted from a high-resistance state to a low-resistance state. Thus, they are ideal candidates for one-time-programmable many-times-readable nonvolatile memories. In this paper, the reliability and the programming characteristics of Si-rich antifuses have been studied using time-dependent dielectric breakdown and pulse-breakdown measurements on both single-device test structures and full read-only memories. Contrary to measurements on thick films in which the Poole–Frenkel barrier lowering dominates breakdown, these measurements on fully processed and integrated antifuses indicate that a Fowler–Nordheim-like mechanism governs both programming and long-term reliability.
Autors: Kaplar, R. J.;Habermehl, S. D.;Apodaca, R. T.;Havener, B.;Roherty-Osmun, E.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2011, volume: 58, issue:1, pages: 224 - 228
Publisher: IEEE
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» Technology and architecture to enable the explosive growth of the internet
Abstract:
At current growth rates, Internet traffic will increase by a factor of one thousand in roughly 20 years. It will be challenging for transmission and routing/switching systems to keep pace with this level of growth without requiring prohibitively large increases in network cost and power consumption. We present a high-level vision for addressing these challenges based on both technological and architectural advancements.
Autors: Saleh, A.A.M.;Simmons, J.M.;
Appeared in: IEEE Communications Magazine
Publication date: Jan 2011, volume: 49, issue:1, pages: 126 - 132
Publisher: IEEE
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» Teleoperation Over the Internet With/Without Velocity Signal
Abstract:
This paper addresses the controller design problem for teleoperation over networks such as the Internet. The forward and backward network transmission time delays are assumed to be asymmetric and time varying, which is the case for computer network communications. We propose a novel master–slave controller, which renders the entire system stable with relatively good steady- and transient-state performances. The relations among the parameters of the controller and the allowable maximum time delays are built in the form of linear matrix inequality. The designed controller is extended to the case that the velocity information is not available. A high-gain observer is designed to estimate the velocities of the master and slave joints online, and the controller is constructed on the basis of the estimated velocities. The stability of the closed-loop system is proved. Both simulations and experiments are performed to verify the correctness and effectiveness of the proposed method.
Autors: Hua, C.;Liu, X. P.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2011, volume: 60, issue:1, pages: 4 - 13
Publisher: IEEE
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» Temperature and electric field dependence of the dielectric property and domain evolution in [001]-oriented 0.34Pb(In1/2Nb1/2)O3–0.25Pb(Mg1/3Nb2/3)O3–0.41PbTiO3 single crystal
Abstract:
Ferroelectric domain structure and evolution, as well as phase transition, of [001]-oriented 34Pb(In1/2Nb1/2)O3–0.25Pb(Mg1/3Nb2/3)O3–0.41PbTiO3 single crystal has been studied through temperature and frequency-dependent relative permittivity characterization. Under dc bias, the transition temperature from rhombohedral-to-tetragonal phases becomes lower and the transition temperature from macrodomain to microdomain structures increases. Phase transition from rhombohedral to tetragonal is confirmed by temperature-dependent x-ray diffraction. These results are also well supported by direct domain observation by means of piezoresponse force microscopy under dc bias at different temperatures, as well as polarization-electric field hysteresis loop measurement.
Autors: Chen, Y.;Lam, K. H.;Zhou, D.;Gao, X. S.;Dai, J. Y.;Luo, H. S.;Chan, H. L. W.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 014111 - 014111-5
Publisher: IEEE
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» Temperature and injection level dependencies and impact of thermal oxidation on carrier lifetimes in p-type and n-type 4H–SiC epilayers
Abstract:
Dependencies of temperature and injection level on carrier lifetimes in 50 μm thick p-type and n-type 4H–SiC epilayers have been investigated. The carrier lifetimes have been measured by differential microwave photoconductance decay measurements at various injection levels and temperatures. In both p-type and n-type epilayers, the carrier lifetimes gradually increased with increasing the injection level, which were naturally expected from the Shockley-Read-Hall (SRH) model, and after taking a maximum, the lifetimes dropped at the very high-injection level. In contrast, the carrier lifetimes exhibited continuous increase with elevating the temperature for both epilayers. In addition, the impact of thermal oxidation process on the carrier lifetimes has been also investigated. The thermal oxidation process, by which the Z1/2 and EH6/7 centers were remarkably reduced that had been observed in n-type 4H–SiC in our previous work, led to the improvement of the carrier lifetimes especially for n-type epilayers. The carrier lifetime reached 4.1 μs in p-type and 6.1 μs in n-type epilayers at 250 °C with an injection level of 1.8×1016 cm-3 through the thermal oxidation processing.
Autors: Hayashi, T.;Asano, K.;Suda, J.;Kimoto, T.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 014505 - 014505-5
Publisher: IEEE
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» Temperature contour maps at the strain-induced martensitic transition of a Cu–Zn–Al shape-memory single crystal
Abstract:
We study temperature changes at the reverse strain-induced martensitic transformation in a Cu–Zn–Al single crystal. Infrared thermal imaging reveals a markedly inhomogeneous temperature distribution. The evolution of the contour temperature maps enables information to be extracted on the kinetics of the interface motion.
Autors: Vives, Eduard;Burrows, Susan;Edwards, Rachel S.;Dixon, Steve;Manosa, Lluis;Planes, Antoni;Romero, Ricardo;
Appeared in: Applied Physics Letters
Publication date: Jan 2011, volume: 98, issue:1, pages: 011902 - 011902-3
Publisher: IEEE
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» Temperature dependence of carrier injection across organic heterojunctions
Abstract:
We present a theoretical and experimental study of carrier injection across organic heterojunctions of various barrier heights (0.4–1.0 eV) over a wide range of temperatures. An injection model with proposed escape probability function wesc is formulated to include the total hopping frequencies at both sides of the heterojunction. The model predicts that the injection current at low temperature can be dramatically modified by an extremely small amount of deep trap states. More importantly, the temperature dependence of the injection current is found to decrease with increasing the barrier height. This suggests that extracting the barrier height from the J versus 1/T plot, as commonly employed in literature, is problematic. Experimentally, hole-only heterojunction devices with injection barrier from 0.4 to 1.0 eV were fabricated by using various organic materials. 4,4,4-tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine was chosen as the injecting layer. The accepting layer was N,N-diphenyl-N,N-bis(1-naphthyl)(1,1-biphenyl)-4,4-diamine, tris(8-hydroxyquinoline) aluminum (Alq), 4,4,4-tris(N-carbazolyl)-triphenylamine, or 2,2,2-(1,3,5-phenylene) tris(1-phenyl-1H-benzimidazole). The measured electric field and temperature dependence of the injection currents of the heterojunction devices were in good agreement with the calculation results.
Autors: Tsang, S. W.;Tao, Y.;Lu, Z. H.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023711 - 023711-7
Publisher: IEEE
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» Temperature effect on the submicron AlGaN/GaN Gunn diodes for terahertz frequency
Abstract:
The wurtzite AlGaN/GaN Gunn diode with tristep-graded Al composition AlGaN as hot electron injector is simulated by using an improved negative differential mobility model of GaN. The results show that the oscillation mode of Gunn diode gradually shifts from dipole domain mode toward accumulation mode with increase in temperature, and the mode shift closely depends on the injector length. At the temperatures of 300–400 K, 0.6 and 0.4 μm Gunn diodes normally generate the oscillation of dipole domain mode, yielding the fundamental oscillation frequencies of 332–352 GHz and 488–508 GHz, respectively, with the dc/rf conversion efficiencies of 2%–3% and the output power densities of 109–1010 Wcm-3. At higher temperatures, the diodes generate the accumulation mode oscillation, and the highest frequency approaches 680 GHz and 977 GHz, respectively, with the dc/rf conversion efficiencies of 0.5%–1%.
Autors: Yang, Linan;Mao, Wei;Yao, Qingyang;Liu, Qi;Zhang, Xuhu;Zhang, Jincheng;Hao, Yue;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 024503 - 024503-6
Publisher: IEEE
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» Temperature tunability of photonic crystal fiber filled with Fe3O4 nanoparticle fluid
Abstract:
Fe3O4 nanoparticles fluid has unique optical properties, which provides versatile possibilities to design state-of-the-art photonic devices. In this paper, by combining Fe3O4 nanoparticles fluid with the photonic crystal fiber (PCF), the spectral characteristics of fluid-filled PCF under different temperatures were experimentally demonstrated. Transmission power and the long wavelength edge of the dip are both found to become highly temperature dependent. The experimental results indicate the slope of this edge is adjustable by changing temperature and there is a linear relationship between transmission power and temperature. This suggests the potential application of this device as an intensity-modulated sensing element or a tunable all-in-fiber gain equalization filter with an adjustable slope.
Autors: Miao, Yinping;Liu, Bo;Zhang, Kailiang;Liu, Yan;Zhang, Hao;
Appeared in: Applied Physics Letters
Publication date: Jan 2011, volume: 98, issue:2, pages: 021103 - 021103-3
Publisher: IEEE
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» Temperature-sensitive nanocapsule for drug delivery
Abstract:
One of the most important applications of nanotechnology is to discover systems for targeted delivery of drugs, that is, designing nanocapsules (nanocontainers). Such nanocapsules have to take effect only in strictly localised areas to avoid drug action on healthy cells. The processes of doxorubicin storage and ejection by the carbon nanocapsule for drug delivery are studied by the method of molecular dynamics. The nanocapsule discussed consists of different nanotubes: (40,40), (10,10), (20,20) and (15,15) joint with each other by pentagonal and heptagonal rings. Nanocapsule stores doxorubicin molecule at normal human body temperature ?? 309.75 K (36.6°C). The doxorubicin molecule is ejected owing to heating and further expansion of the gas inside the nanocapsule. The gas pushes the fullerene-piston, which ejects the doxorubicin molecule out of the nanocapsule. The temperature required for doxorubicin ejection is 316.75 K (43.6°C). The temperature elevation can be reached with infrared radiation.
Autors: Suyetin, M.V.;Vakhrushev, A.V.;
Appeared in: IET Micro & Nano Letters
Publication date: Jan 2011, volume: 6, issue:1, pages: 39 - 42
Publisher: IEEE
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» Temporal Analysis of Exploding Film Burst Phenomenon
Abstract:
A technique to determine the time of burst for exploding aluminum metallized films has been studied. An experimental approach has been taken to determine the burst time relative to the discharge current, voltage, resistance, and power waveforms. A microphone transducer was employed to detect the time of burst from the sound produced by the bursting of the film and was compared to the calculated burst times. A theoretical discussion on the energy needed to melt and vaporize the film is also presented and compared to the experimental results.
Autors: DiSanto, T. M.;Olabisi, S.;Muffoletto, D. P.;Burke, K. M.;Moore, H. L.;Singh, H.;Zirnheld, J. L.;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2011, volume: 39, issue:1, pages: 603 - 607
Publisher: IEEE
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» Temporal Sequence Parameters in Isodistributional Surrogate Data: Model and Exact Expressions
Abstract:
In this paper, a set of formulae for the temporal spontaneous baroreceptor reflex (sBRR) sequence parameters in isodistributional (ID) surrogate data is derived. This is facilitated by representing successive positive or negative amplitude changes as a Markov chain model. The obtained analytical tool measures the effect of random fluctuations on the overall number of sequences, estimated from the original biomedical time series. The formulae are tested using ID surrogates of systolic blood pressure and pulse-interval signals recorded from 13 healthy male Wistar rats at baseline conditions.
Autors: Turukalo, T.;Bajic*, D.;Zigon, N.;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jan 2011, volume: 58, issue:1, pages: 16 - 24
Publisher: IEEE
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» Terahertz generation by photoconductors made from low-temperature-grown GaAs annealed at moderate temperatures
Abstract:
A terahertz time-domain spectroscopy system based on a femtosecond Yb:KGW laser, photoconductive emitters made using a low-temperature- grown (LTG) GaAs layer annealed at different temperatures, and a photoconductive detector made using a Si-doped GaBiAs epitaxial layer, has been demonstrated. Useful spectral bandwidth of the system, that might be used in spectroscopy experiments, was up to 3 THz and its dynamical range exceeded 50 dB when the LTG GaAs emitter annealed at 420°C was used. It has been concluded that the breakdown field of as-grown layers is much larger than that of annealed layers; this process provides rather large optical-to-THz radiation conversion efficiencies for the emitters made from moderately annealed LTG GaAs.
Autors: Biciunas, A.;Geizutis, A.;Krotkus, A.;
Appeared in: Electronics Letters
Publication date: Jan 2011, volume: 47, issue:2, pages: 130 - 132
Publisher: IEEE
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» The Base Stock/Base Backlog Control Policy for a Make-to-Stock System With Impatient Customers
Abstract:
We study a single-stage production system that produces one product type. The system employs a base stock policy to maintain an inventory of finished items and cope with random demand. During stockout periods, the system incurs three types of potential customer loss: (a) balking, i.e., arriving customers may be unwilling to place orders and leave immediately; (b) rejection, i.e., the system rejects new customer orders if its backlog has reached a certain limit, called the base backlog; (c) reneging, i.e., outstanding customers waiting in queue may become impatient and withdraw their orders. The objective is to determine the base stock and base backlog that maximize the mean profit rate of the system. This quantity is estimated analytically using a finite capacity M/M/1 queueing model, in which the arrival rate is a decreasing but otherwise arbitrary function of the backlog and customer reneging times have an arbitrary but known distribution. Certain properties are established which ensure that the optimal control parameters can be determined in finite time by exhaustive search. The model is then extended to take into account a fixed order quantity policy for replenishing raw material. Numerical results show that managing inventories and backlog jointly achieves higher profit than other control policies.
Autors: Economopoulos, A. A.;Kouikoglou, V. S.;Grigoroudis, E.;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jan 2011, volume: 8, issue:1, pages: 243 - 249
Publisher: IEEE
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» The changing face of electronic ID
Abstract:
Electronic versions of secure identification documents, also known as e-documents, have evolved rapidly in recent years and are now beginning to supersede their paper-based counterparts. What's more, they are increasingly capitalising on biometric data to establish a unique connection between the document and its owner.
Autors: Maik, Pogoda
Appeared in: Biometric Technology Today
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» The Client and the Cloud: Democratizing Research Computing
Abstract:
Extending the capabilities of PC, Web, and mobile applications through on-demand cloud services will significantly broaden the research community's capabilities, accelerating the pace of engineering and scientific discovery in this age of data-driven research. The net effect will be the democratization of research capabilities that are now available only to the most elite scientists. To make this vision a reality, the computer systems research community must develop new approaches to building client-plus-cloud applications to support a new type of science, and many technical challenges exist.
Autors: Barga, Roger;Gannon, Dennis;Reed, Daniel;
Appeared in: IEEE Internet Computing
Publication date: Jan 2011, volume: 15, issue:1, pages: 72 - 75
Publisher: IEEE
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» The Compact Circularly-Polarized Hollow Rectangular Dielectric Resonator Antenna With an Underlaid Quadrature Coupler
Abstract:
The wideband circularly polarized (CP) dielectric resonator antenna (DRA) is investigated with an underlaid quadrature coupler. The idea is used to realize a CP hollow rectangular DRA. Since the coupler is located beneath the DRA, it does not increase the footprint of the antenna, making the system very compact. The underlaid coupler is placed entirely inside the hollow region of the DRA and, thus, it can be designed easily as if there is no overlaid DRA. Two configurations are considered in this paper. In the first configuration, an external 50- load is used for the matching port of the coupler. For the second one, a strip loaded by the DRA is used to provide a load and, thus, no lumped elements are required in this configuration. In this paper, a network model is also given to aid engineers in designing the proposed integrated DRA. The reflection coefficient, axial ratio, antenna gain, and radiation pattern for each configuration are studied. It was found that wide impedance and axial-ratio bandwidths can be obtained with the proposed CP DRAs. Measurements were carried out to verify the simulations, and reasonable agreement between them was obtained.
Autors: Lim, E. H.;Leung, K. W.;Fang, X. S.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2011, volume: 59, issue:1, pages: 288 - 293
Publisher: IEEE
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» The detection of terahertz waves by semimetallic and by semiconducting materials
Abstract:
We present a survey of photoresponse (PR) measurements of various devices containing quantum wells (QWs) of HgTe of various widths dQW and of InSb. By varying dQW for HgTe, the material properties of the QW material change from semiconducting to semimetallic as dQW is increased above a value of about 6nm. We have studied the PR of devices made from CdxHg1-xTe/HgTe/CdxHg1-xTe wafers with values of the QW width in the range of 6 nm≤dQW≤21 nm. Only for samples with semimetallic HgTe QWs, a measurable PR could be detected. However, our investigations of samples made from AlxIn1-xSb/InSb/AlxIn1-xSb wafers gave evidence that a measurable PR also can appear from devices with a semiconducting QW. Both cyclotron-resonant (CR) and nonresonant (bolometric, BO) interaction mechanisms can contribute to the PR signal. Whereas the CR contribution is dominant in AlxIn1-xSb/InSb/AlxIn1-xSb samples, in CdxHg1-xTe/HgTe/CdxHg1-xTe samples the behavior is more complex. In a sample with dQW=8 nm, the PR is clearly dominated - - by the BO contribution. In the PR of another sample of dQW=12 nm, both contributions (BO and CR) are present. The sample of dQW=21 nm shows a PR with not clearly separable BO and CR contributions.
Autors: Gouider, F.;Nachtwei, G.;Brune, C.;Buhmann, H.;Vasilyev, Yu. B.;Salman, M.;Konemann, J.;Buckle, P. D.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013106 - 013106-5
Publisher: IEEE
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» The Effect of Adhesive on Arc Behaviors of Laser-TIG Hybrid Weld Bonding Process of Mg to Al Alloy
Abstract:
The effect of adhesive on arc behaviors was investigated during the laser-TIG hybrid weld bonding process of Mg to Al alloy. The welding plasma shape, optical spectrum, current, and voltage were acquired by plasma behavior analytic system which was composed of high speed camera, optical spectrometer, digital oscilloscope, and personal computer. For comparison, the laser-TIG hybrid welding without adhesive was conducted under the same conditions. The results showed that the addition of the adhesive increased the pressure inside the laser keyhole, leading to a severe jet of metal vapor. Much more Mg atoms entered the arc plasma, ionizing instead of Ar atoms. The electron temperature of arc plasma was decreased. In contrast, the electron density of arc plasma was increased. Moreover, the arc current path was contracted by the thermal pinch effect. Further, the welding voltage was increased. Welding efficiency was increased, and the deeper penetration was obtained.
Autors: Liu, L.;Jiang, J.;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2011, volume: 39, issue:1, pages: 581 - 586
Publisher: IEEE
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» The effect of heat treatment process on structure and properties of ZnO nano layer produced by sol-gel method
Abstract:
ZnO nano layer was prepared by sol-gel method using zinc acetate dihydrate, methanol and diethanolamine as precursor, solvent and stabilizer, respectively. According to the thermal analysis results, the heat treatment process after producing ZnO nano layer can be divided into three stages. The structure of the nano layer showed a significant dependency on heat treatment temperature in the low temperature heat treatment stage, which is performed to evaporate the organic components. The high temperature heat treatment stage has no significant effect on the structure of the films. The temperature employed in the first stage of heat treatment process during the...
Autors: Seyyed Mohammad, Hossein Hejazi , Fatemeh, Majidi , Mohammad, Pirhadi Tavandashti , Mohammad, Ranjbar
Appeared in: Materials Science in Semiconductor Processing
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» The Effect of Insulating Layers on the Performance of Implanted Antennas
Abstract:
This work presents the analysis of the influence of insulation on implanted antennas for biotelemetry applications in the Medical Device Radiocommunications Service band. Our goal is finding the insulation properties that facilitate power transmission, thus enhancing the communication between the implanted antenna and an external receiver. For this purpose, it has been found that a simplified model of human tissues based on spherical geometries excited by ideal sources (electric dipole, magnetic dipole and Huygens source) provides reasonable accuracy while remaining very tractable due to its analytical formulation. Our results show that a proper choice of the biocompatible internal insulation material can improve the radiation efficiency of the implanted antenna (up to six times for the investigated cases). External insulation facilitates the electromagnetic transition from the biological tissue to the outer free space, reducing the power absorbed by the human body. Summarizing, this work gives insights on the enhancement of power transmission, obtained with the use of both internal, biocompatible and external, flexible insulations. Therefore, it provides useful information for the design of implanted antennas.
Autors: Merli, F.;Fuchs, B.;Mosig, J. R.;Skrivervik, A. K.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2011, volume: 59, issue:1, pages: 21 - 31
Publisher: IEEE
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» The effect of intensity of excitation on CdSe/ZnS quantum dots: Opportunities in luminescence sensing
Abstract:
We report changes in the photophysical properties of core-shell type CdSe/ZnS quantum dots (QDs) under optical irradiation. QDs either in aqueous solution or immobilized in a silica sol gel matrix have been excited at different wavelengths and fluxes. Illumination of the sample with 140 fs 700 nm Ti:sapphire laser pulses of the peak power of the order of 4 GW/cm2 caused gradual increase in the luminescence lifetime from an initial value of 3.5 increasing to 4.5 ns and an increase in luminescence intensity by ∼8%. Using about 16 GW/cm2 peak power resulted in a shortening of the luminescence lifetime to 3 ns and a decrease in intensity by ∼75%. Both photobrightening and photodarkening were fully reversible. We discuss the kinetics of photobrightening and photodarkening and investigate the suitability of QDs as luminescence lifetime sensors with tunable parameters.
Autors: Sutter, Jens U.;Birch, David J. S.;Rolinski, Olaf J.;
Appeared in: Applied Physics Letters
Publication date: Jan 2011, volume: 98, issue:2, pages: 021108 - 021108-3
Publisher: IEEE
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» The effect of interface processing on the distribution of interfacial defect states and the C-V characteristics of III-V metal-oxide-semiconductor field effect transistors
Abstract:
We have investigated the effect of interface formation and processing conditions of Al2O3 on GaAs on the density and distribution of interface state charge in the band gap. We have formed the insulator/semiconductor interface using both atomic layer deposition (ALD) and chemical vapor deposition (CVD). In situ ALD, ex situ ALD, and in situ CVD of aluminum oxide (Al2O3) on GaAs were employed using metal-organic CVD. Isopropanol (IPA) was chosen as the oxygen source for Al2O3 deposition. No arsenic or gallium oxide was detected at the in situ ALD Al2O3/GaAs interface, while gallium oxide was observed at the in situ CVD Al2O3/GaAs interface. The entire distributions of interfacial defects from different processes were determined by conductance frequency method with temperature-variation capacitance-voltage (C-V) measurements. The existence of Ga2O3 at the interface was found to be a possible method to lower the density of midgap defect states. From the C-V simulation, the midgap defect states are acceptorlike, which may originate from gallium vacancies near the interface. These states may also result in high frequency dispersion observed in the C-V curves of n-type metal-oxide-semiconductor field effect transistors. We correlate the interfacial defect states with the processes used to form the insulator-semiconductor interface.
Autors: Cheng, Cheng-Wei;Apostolopoulos, George;Fitzgerald, Eugene A.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023714 - 023714-8
Publisher: IEEE
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» The effect of nitrogen plasma anneals on interface trap density and channel mobility for 4H-SiC MOS devices
Abstract:
 Research highlights: ? Use a nitrogen plasma to successfully introduce nitrogen into SiO2/SiC interface. ? N Conc. at the interface is 1×1014cm-2, ~1/6 of the saturated N Conc. by NO anneal. ? This process reduces DIT and results in peak channel mobility at about 50cm2/Vs.

Autors: We report results on the introduction of nitrogen at the SiC/SiO2 interface using a plasma process, thus avoiding the detrimental effects of additional oxidation that accompany other standard nitridation processes, such as annealing in NO gas. The pl
Appeared in: Solid-State Electronics
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» The Effect of Orientation Angle Compensation on Coherency Matrix and Polarimetric Target Decompositions
Abstract:
The polarization orientation angle (OA) of the scattering media affects the polarimetric radar signatures. This paper investigates the effects of orientation compensation on the coherency matrix and the scattering-model-based decompositions by Freeman–Durden and Yamaguchi The Cloude and Pottier decomposition is excluded, because entropy, anisotropy, and alpha angle are roll invariant. We will show that, after orientation compensation, the volume scattering power is consistently decreased, while the double-bounce power has increased. The surface scattering power is relatively unchanged, and the helicity power is roll invariant. All of these characteristics can be explained by the compensation effect on the nine elements of the coherency matrix. In particular, after compensation, the real part of the correlation reduces to zero, the intensity of cross-pol always reduces, and always increases. This analysis also reveals that the common perception that OA compensation would make a reflection asymmetrical medium completely reflection symmetric is incorrect and that, contrary to the general perception, the four-component decomposition does not use the complete information of the coherency matrix. Only six quantities are included—one more than the Freeman–Durden decomposition, which explicitly assumes refection symmetry.
Autors: Lee, J.-S.;Ainsworth, T. L.;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jan 2011, volume: 49, issue:1, pages: 53 - 64
Publisher: IEEE
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» The elastic-plastic response of aluminum films to ultrafast laser-generated shocks
Abstract:
We present the free surface response of 2, 5, and 8 μm aluminum films to shocks generated from chirped ultrafast lasers. We find two distinct steps to the measured free surface velocity that indicate a separation of the faster elastic wave from the slower plastic wave. We resolve the separation of the two waves to times as short as 20 ps. We measured peak elastic free surface velocities as high as 1.4 km/s corresponding to elastic stresses of 12 GPa. The elastic waves rapidly decay with increasing sample thickness. The magnitude of both the elastic wave and the plastic wave and the temporal separation between them was strongly dependent on the incident laser drive energy.
Autors: Whitley, V. H.;McGrane, S. D.;Eakins, D. E.;Bolme, C. A.;Moore, D. S.;Bingert, J. F.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013505 - 013505-4
Publisher: IEEE
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» The encapsulation of an organic light-emitting diode using organic-inorganic hybrid materials and MgO
Abstract:
image

Autors:

Graphical abstract

 Graphical abstract:  Research highlights: ? Organic-inorganic hybrid materials and MgO were used for multi-barriers. ? The WVTR value of 4.9×10-5g/m2day and transmittance of 81.8% were obtained for the 6-dyads multi-barrie
Appeared in: Organic Electronics
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» The Evolution of Flight Management Systems
Abstract:
In 1978, Honeywell began developing its flight management system (FMS), putting the first FMS into service as standard equipment in 1982 on the Boeing B757 and B767. Now, every major aircraft manufacturer includes a Honeywell FMS in the cockpit. In total, the Honeywell FMS has 15 distinct baselines flying on more than 14,000 aircraft. It currently totals around a million source LOC and increases by perhaps 2 percent per year. R&D is already underway for innovations and improvements to both new and existing technologies: 4D trajectories, future air navigation systems, required time of arrival, and trajectory-based optimization.
Autors: Avery, David;
Appeared in: IEEE Software
Publication date: Jan 2011, volume: 28, issue:1, pages: 11 - 13
Publisher: IEEE
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» The future of services in next generation networks
Abstract:
With the advent of Web 2.0 and service oriented architecture (SOA) technologies, service creation paradigms have undergone profound changes. Such a revolution made telecommunication (telco) vendors pit themselves against Internet technology (IT) vendors in the battle for service development market share.
Autors: Simoes, J.;Wahle, S.;
Appeared in: IEEE Potentials
Publication date: Jan 2011, volume: 30, issue:1, pages: 24 - 29
Publisher: IEEE
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» The Future Renewable Electric Energy Delivery and Management (FREEDM) System: The Energy Internet
Abstract:
This paper presents an architecture for a future electric power distribution system that is suitable for plug-and-play of distributed renewable energy and distributed energy storage devices. Motivated by the success of the (information) Internet, the architecture described in this paper was proposed by the NSF FREEDM Systems Center, Raleigh, NC, as a roadmap for a future automated and flexible electric power distribution system. In the envisioned “Energy Internet,” a system that enables flexible energy sharing is proposed for consumers in a residential distribution system. The key technologies required to achieve such a vision are presented in this paper as a result of the research partnership of the FREEDM Systems Center.
Autors: Huang, A. Q.;Crow, M. L.;Heydt, G. T.;Zheng, J. P.;Dale, S. J.;
Appeared in: Proceedings of the IEEE
Publication date: Jan 2011, volume: 99, issue:1, pages: 133 - 148
Publisher: IEEE
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» The Geometric Efficient Matching Algorithm for Firewalls
Abstract:
Since firewalls need to filter all the traffic crossing the network perimeter, they should be able to sustain a very high throughput, or risk becoming a bottleneck. Firewall packet matching can be viewed as a point location problem: Each packet (point) has five fields (dimensions), which need to be checked against every firewall rule in order to find the first matching rule. Thus, algorithms from computational geometry can be applied. In this paper, we consider a classical algorithm that we adapted to the firewall domain. We call the resulting algorithm “Geometric Efficient Matching” (GEM). The GEM algorithm enjoys a logarithmic matching time performance. However, the algorithm's theoretical worst-case space complexity is O(n4) for a rule-base with n rules. Because of this perceived high space complexity, GEM-like algorithms were rejected as impractical by earlier works. Contrary to this conclusion, this paper shows that GEM is actually an excellent choice. Based on statistics from real firewall rule-bases, we created a Perimeter rules model that generates random, but nonuniform, rule-bases. We evaluated GEM via extensive simulation using the Perimeter rules model. Our simulations show that on such rule-bases, GEM uses near-linear space, and only needs approximately 13 MB of space for rule-bases of 5,000 rules. Moreover, with use of additional space improving heuristics, we have been able to reduce the space requirement to 2-3 MB for 5,000 rules. But most importantly, we integrated GEM into the code of the Linux iptables open-source firewall, and tested it on real traffic loads. Our GEM-iptables implementation managed to filter over 30,000 packets-per-second on a standard PC, even with 10,000 rules. Therefore, we believe that GEM is an efficient and practical algorithm for firewall packet matching.
Autors: Rovniagin, D.;Wool, A.;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jan 2011, volume: 8, issue:1, pages: 147 - 159
Publisher: IEEE
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» The Green Defenders
Abstract:
The Smart Grid System will Deliver Electricity from producers to consumers using digital communications technology in order to conserve energy and increase reliability. Since the power grid system is one of the critical infrastructures in each country, however, the damage from various types of cyberattacks would result in tremendous disasters. Several cases of cyberattacks against power grids have been reported in various media and research conferences, and it is probable that the main target in the next cyberwar would be the smart grid system. In this article, we will look at the various cyberthreats and at efforts to enhance the cybersecurity of the smart grid system.
Autors: Jung-taek Seo;Cheolwon Lee;
Appeared in: IEEE Power and Energy Magazine
Publication date: Jan 2011, volume: 9, issue:1, pages: 82 - 90
Publisher: IEEE
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» The iDUDE Framework for Grayscale Image Denoising
Abstract:
We present an extension of the discrete universal denoiser DUDE, specialized for the denoising of grayscale images. The original DUDE is a low-complexity algorithm aimed at recovering discrete sequences corrupted by discrete memoryless noise of known statistical characteristics. It is universal, in the sense of asymptotically achieving, without access to any information on the statistics of the clean sequence, the same performance as the best denoiser that does have access to such information. The DUDE, however, is not effective on grayscale images of practical size. The difficulty lies in the fact that one of the DUDE's key components is the determination of conditional empirical probability distributions of image samples, given the sample values in their neighborhood. When the alphabet is relatively large (as is the case with grayscale images), even for a small-sized neighborhood, the required distributions would be estimated from a large collection of sparse statistics, resulting in poor estimates that would not enable effective denoising. The present work enhances the basic DUDE scheme by incorporating statistical modeling tools that have proven successful in addressing similar issues in lossless image compression. Instantiations of the enhanced framework, which is referred to as iDUDE, are described for examples of additive and nonadditive noise. The resulting denoisers significantly surpass the state of the art in the case of salt and pepper (S&P) and -ary symmetric noise, and perform well for Gaussian noise.
Autors: Motta, G.;Ordentlich, E.;Ramirez, I.;Seroussi, G.;Weinberger, M. J.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jan 2011, volume: 20, issue:1, pages: 1 - 21
Publisher: IEEE
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» The influence of thermal stresses on the phase composition of 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 thick films
Abstract:
The influence of thermal stresses versus the phase composition for 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (0.65PMN–0.35PT) thick films is being reported. The thermal residual stresses in the films have been calculated using the finite-element method. It has been observed that in 0.65PMN–0.35PT films a compressive stress enhances the thermodynamic stability of the tetragonal phase with the space group P4mm.
Autors: Ursic, Hana;Zarnik, Marina Santo;Tellier, Jenny;Hrovat, Marko;Holc, Janez;Kosec, Marija;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 014101 - 014101-5
Publisher: IEEE
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» The Internet [The way I see it]
Abstract:
The Internet is known as one of the most popular inventions during this century. Nowadays, it has become a part of our environment. In fact, people from all over the world use it to communicate, share knowledge, receive and send information, and play games, among other functions. Nevertheless, using the Internet can have several impacts on people at different ages. It can be a double- edged sword and have both positive and negative effects, especially with young people.
Autors: Hamdani, M.;Moszkowicz, U.;
Appeared in: IEEE Potentials
Publication date: Jan 2011, volume: 30, issue:1, pages: 8 - 9
Publisher: IEEE
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» The jacked-in decade [Spectral Lines]
Abstract:
Connectedness is now a given. Smartphones offer us advice, the Internet carries our voices and video, the cloud archives our data, and e-readers pull it to Earth again. We share all this stuff and more via our social networks. Behind the scenes, brainy grids juggle power, and vast military networks stretch out to robotic planes equipped with devastating firepower above distant battlefields. Nothing seems to happen anymore without global resources coming into play.
Autors: Ross, P.E.;
Appeared in: IEEE Spectrum
Publication date: Jan 2011, volume: 48, issue:1, pages: 8 - 8
Publisher: IEEE
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» The lightbulb that really is a better idea [Tools & Toys]
Abstract:
Five years ago they were in the lab; now you can buy LED lightbulbs at a hardware store. Should you? They produce as much light as incandescent bulbs for less than a fifth the electricity and heat, they last up to 20 years, and they fit in standard sockets.
Autors: Wallich, P.;
Appeared in: IEEE Spectrum
Publication date: Jan 2011, volume: 48, issue:1, pages: 20 - 22
Publisher: IEEE
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» The log_2{N-1} Optical Switching Fabrics
Abstract:
In this article, we introduce a new space-division optical switching fabric architecture based on baseline switching networks. The new structure is built from optical switching elements (OSE) 2 x 2, 3 x 3, 2 x 3, and 3 x 2. The new structure is called the log_2{N-1} switching network and consists of fewer numbers of active and passive optical elements than traditional baseline switching networks composed of symmetrical OSEs. In the paper, we investigate space-division multiplane strict-sense and rearrangeable log_2{N-1} nonblocking switching networks and compare these with space-division multiplane baseline switching networks. The new structure has lower cost than other architectures for strict-sense nonblocking (SSNB) conditions and for rearrangeable (RNB) networks with odd number of stages. For RNB networks, when the number of stages is even, the cost of the multiplane log_2{N-1} optical switching network is equal to or higher than traditional networks.
Autors: Danilewicz, Grzegorz;Kabacinski, Wojciech;Rajewski, Remigiusz;
Appeared in: IEEE Transactions on Communications
Publication date: Jan 2011, volume: 59, issue:1, pages: 213 - 225
Publisher: IEEE
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» The mechanical performance of cordwood
Abstract:
 Research highlights: ? Mechanical testing of cordwood samples manufactured with logs at 30% water. ? Compressive behaviour of organic aggregates mortar. ? Compressive behaviour of 2 cordwood samples with chestnut and spruce wood logs. ? Assessing the elasto-plastic behaviour of cordwood. ? Stiffness of two cordwood log arrangements.

Autors: Cordwood structures are used by only a few independent builders and to date the only real technical development has existed in North America. However, cordwood structures could help reduce environmental impact because cordwood has very low embodied e
Appeared in: Biosystems Engineering
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» The Migration to the Middle
Abstract:
As we look to the future, we must not only anticipate a year of innovation and progress but also a migration of labor that will remake the field of digital technology.
Autors: Grier, David Alan;
Appeared in: Computer
Publication date: Jan 2011, volume: 44, issue:1, pages: 12 - 14
Publisher: IEEE
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» The Modified Harmonic Domain: Interharmonics
Abstract:
This paper presents the basics of two techniques, named here as the modified harmonic domain and the modified dynamic harmonic domain, proposed for calculating steady and dynamic states, respectively. These techniques have their fundament in the harmonic domain with a substantial improvement: the inclusion of interharmonics in either steady or dynamic state. This is performed through the use of the discrete Fourier transform which allows an arbitrary frequency-domain discretization, thus permitting the representation of interharmonics.
Autors: Ramirez, A.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jan 2011, volume: 26, issue:1, pages: 235 - 241
Publisher: IEEE
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» The MPEG Interactive Music Application Format Standard [Standards in a Nutshell]
Abstract:
The music industry is going through a transformation, and new interactive music services have emerged. It is envisaged that this new concept of digital music content will dominate the next generation of music services. A standardized file format is inevitably required to provide the interoperability between various interactive music players and interactive music albums. This issue is addressed in a new standard by the Moving Picture Experts Group (MPEG), known as the MPEG-A Interactive Music Application Format (IM AF). IM AF integrates multiple audio tracks with appropriate additional information, enabling users to experience various preset mixes and to make their own mixes complying with interactivity rules imposed by the music composers with the aim of fitting their artistic creation.
Autors: Jang, I.;Kudumakis, P.;Sandler, M.;Kang, K.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2011, volume: 28, issue:1, pages: 150 - 154
Publisher: IEEE
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» The New Education Department and Editorial Board Members
Abstract:
Editor in Chief Gabriel Taubin introduces two new editorial board members, Scott Owen and Cindy Grimm. Gitta Domik introduces her new Education department, coedited with Scott Owen.
Autors: Taubin, Gabriel;
Appeared in: IEEE Computer Graphics and Applications
Publication date: Jan 2011, volume: 31, issue:1, pages: 5 - 6
Publisher: IEEE
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» The optimum conditions for solid-state-prepared (Y3-xCex)Al5O12 phosphor using the Taguchi method
Abstract:
Using the Taguchi method, the authors analyzed the optimum conditions for (Y3-xCex)Al5O12 (YAG:Ce) phosphor, which is prepared using the solid-state reaction method. The controllable factors used in this study consisted of the following: (1) the duration of milling, (2) the quantity of substitution, (3) the duration of sintering, and (4) the temperature of sintering. Under optimum conditions, a confirmation experiment was carried out, and the average photoluminescence (PL) intensity of YAG:Ce phosphor was found to be up to 270.84 (a.u.). The percentage contribution of each controllable factor was also determined. Most interestingly, the temperature of sintering is the most influential...
Autors: Chuen-Shii, Chou , Chun-Yu, Wu , Chun-Hung, Yeh , Ru-Yuan, Yang , Jin-Hsiang, Chen
Appeared in: Advanced Powder Technology
Publication date: Jan 2011
Publisher: Elsevier B.V.
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» The Promise and Peril of Social Computing
Abstract:
Social computing has the potential to fundamentally change the structure of human relationships. Will it succeed?
Autors: Riedl, John;
Appeared in: Computer
Publication date: Jan 2011, volume: 44, issue:1, pages: 93 - 95
Publisher: IEEE
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» The Provision of Frequency Control Reserves From Multiple Microgrids
Abstract:
The concept of microgrid is invented to harmonize local electricity production and consumption. The increasing interest on microgrids is caused by the considerable growth of renewable energy sources (RES) and distributed generation (DG). In a large geographical region, there can exist multiple microgrids. Many academic articles have reported the technicalities of microgrids operating in islanded mode, and few have analyzed their aggregated technical/economic impacts or benefits on the network in a larger region. Deregulation encourages RES to participate in energy markets to facilitate competition among different energy providers. Apart from participating in energy markets, an alternative way of making use of and making profit out of multiple microgrids is to take part in the ancillary-service market. This paper investigates the technical aspects of providing frequency control reserves (FCRs) and the potential economic profitability of participating in FCR markets based on a setup of multiple microgrids. In particular, it has a focus on the communication aspects under different market scenarios, i.e., decentralized or centralized coordination approach, for FCRs with the assumption of the possible aggregation of reserve provision from multiple microgrids (microsources and flexible loads).
Autors: Yuen, C.;Oudalov, A.;Timbus, A.;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2011, volume: 58, issue:1, pages: 173 - 183
Publisher: IEEE
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» The Road Ahead
Abstract:
The new editor in chief of IEEE Software magazine briefly outlines his vision for the future, including items regarding new digital content and possibilities for reader-author interaction. This EIC message also contains an erratum to the Nov./Dec. 2010 article, "Visual Tools for Software Architecture Understanding: A Stakeholder Perspective," by Alexandru Telea, Lucian Voinea, SolidSource BV, and Hans Sassenburg. The erratum corrects a URL in Figure 1.
Autors: Shull, Forrest;
Appeared in: IEEE Software
Publication date: Jan 2011, volume: 28, issue:1, pages: 2 - 4
Publisher: IEEE
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