bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of dispersive microwave FET devices using a quasi‐static approach
Authors: Kompa Günter 
Published: July 2007

AbstractIn the design of active microwave circuits nonlinear device models are of great importance to allow one to predict the reliability of circuit performance. This article reflects our experimental approach in nonlinear FET modeling. Consistent bias‐dependent model elements of the FET small‐signal equivalent circuit are obtained by a recently developed unique multibias extraction procedure which permits the reduction of the nonlinear analysis to the inner part of a FET device. A dispersive nonlinear FET model with current and charge sources being integral functions of the bias‐dependent small‐signal model parameters is proposed. A bias‐dependent difference transconductance and difference channel conductance are introduced as relevant dispersion parameters. The proposed nonlinear FET model is verified on the basis of our signal waveform measurement technique using combined frequency‐ and time‐domain signal detection.
Steady state analysis of free or forced oscillators by harmonic balance and stability investigation of periodic and quasi‐periodic regimes
Authors: Ngoya Edouard , Suárez Almudena , Sommet Raphaël , Quéré Raymond 
Published: July 2007

AbstractThis article presents a practical and effective method to analyze the steady state regimes, periodic or quasi‐periodic, and the stability of free and forced oscillators, based on the use of voltage and current probes. The efficiency of this method comes from the fact that it converts the analysis of an autonomous circuit into the analysis of a series of closely related nonautonomous circuits, which in turn relies on the power of the harmonic balance equation for these kinds of systems. The effectiveness of the method is shown by full analysis of a practical example.
Steady‐state analysis of nonlinear forced and autonomous microwave circuits using the compression approach
Authors: Kunisch Jürgen , Wolff Ingo 
Published: July 2007

AbstractThis article discusses techniques for the analysis of nonlinear microwave circuits that contain lumped nonlinear elements. Emphasis is put on specific harmonic balance‐based technique which allows us to retain the field theoretical accuracy in cases where lumped nonlinear elements are embedded closely within complex metallization structures. © 1995 John Wiley & Sons, Inc.
The effects of finite dielectric layers in multilevel microstrip interconnects
Authors: Engel Andrew G. , Katehi Linda P. B. 
Published: July 2007

AbstractMicrostrip with finite‐width substrate and ground plane and coupled multilevel microstrip with a finite‐width intermediate dielectric layer are examined with an integral equation‐mode matching method. The effects of varying the distance of a microstrip from the edge of a finite‐width substrate and ground plane are studied in the frequency and time domains. Coupled multilevel microstrip with a finite‐width and homogeneous intermediate layer are also characterized in the frequency and time domains, and the coupling between the two lines is found to be much greater when the intermediate layer is finite. © 1995 John Wiley & Sons. Inc.
Efficient use of commercial electromagnetic simulators for microwave and millimeter‐wave circuits
Authors: Jain Nitin , Onno Peter 
Published: July 2007

AbstractEfficient use of electromagnetic simulators is accomplished by classification of EM problems into three categories—characterization of circuit elements, optimization of circuit elements, and creation of circuit element libraries. Real circuit examples in each of the three categories are given to demonstrate the practical aspects of efficient EM simulations and the computer resources required. © 1995 John Wiley & Sons, Inc.
Electromagnetic design of high‐temperature superconducting microwave filters
Authors: Bandler John W. , Biernacki Radoslaw M. , Chen Shao Hua , Getsinger William J. , Grobelny Piotr A. , Moskowitz Charles , Talisa Salvador H. 
Published: July 2007

AbstractWe present novel approaches to electromagnetic design of high‐temperature superconducting (HTS) quarter‐wave parallel coupled‐line microstrip filters. The desired narrow bandwidths (less than 2%) coupled with the large dielectric constant of substrate materials used in the HTS technology (εr≈ 24) make the design problems difficult to treat accurately for many traditional microwave circuit design software packages with analytical/empirical models. We have successfully performed an HTS filter design with accurate electromagnetic field simulations. We discuss problems related to electromagnetic design of such filters. We describe a look‐up table method and a powerful space mapping optimization technique, which dramatically reduce the CPU time needed in the design process. Finally, we address the issue of improved modeling of the HTS filter using analytical/empirical models. © 1995 John Wiley & Sons, Inc.
Glucuronidation of curcuminoids by human microsomal and recombinant UDP‐glucuronosyltransferases
Authors: Hoehle Simone I. , Pfeiffer Erika , Metzler Manfred 
Published: July 2007

AbstractGlucuronidation is an important pathway in the metabolism of curcumin, but the isoforms of uridine‐5′‐diphosphoglucuronosyltransferase (UGT) involved are not known. Here, we report on the glucuronidation of the three natural curcuminoids and their major phase I metabolites with microsomes from human liver and intestine as well as with human recombinant UGTs. Microsomes from human liver generated predominantly the phenolic and small amounts of the alcoholic glucuronide of each curcuminoid, whereas intestinal microsomes formed only the phenolic conjugates but with higher activities. The phenolic glucuronidation of the curcuminoids was predominantly catalyzed by hepatic UGT1A1 and intestinal UGT1A8 and 1A10, whereas UGT1A9, 2B7, and 1A8 exhibited high activities for hexahydro‐curcuminoids. UGT1A9 was able to form the alcoholic glucuronide of each curcuminoid in addition to the phenolic conjugate. These data suggest that the gastrointestinal tract contributes substantially to the glucuronidation of curcuminoids in humans, which may have important implications for their pharmacokinetic fatein vivo.
White‐marker imaging—Separating magnetic susceptibility effects from partial volume effects
Authors: Seppenwoolde Jan‐Henry , Vincken Koen L. , Bakker Chris J.G. 
Published: July 2007

AbstractBy applying dephasing gradients, local magnetic field inhomogeneitiescan selectively visualized with positive contrast, such as those created by magnetically labeled cells. This is known as “white‐marker imaging.” In white‐marker imaging, subvoxel signal variations are also visualized as a result of partial volume (PV) effects and may compromise the identification of magnetic structures (e.g., magnetically‐labeled cells). This study presents the theory and proof‐of‐principle experiments of a strategy to eliminate PV effects during white‐marker imaging. The strategy employs the asymmetry of the signal response curves for non‐PV effects as a function of externally applied gradients. In the case of PV effects, subtraction of the symmetrical signal responses eliminates their contribution. In vitro experimental images were made using a spherical phantom with cylindrical elements. In vivo images of the brain were obtained at a location that included air cavities (susceptibility effects) and the circle of Willis (PV effect). The results show that PV effects were eliminated in the in vitro experiments and were virtually absent under in vivo conditions. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Absolute quantification of phosphorus metabolite concentrations in human muscle in vivo by 31P MRS: a quantitative review
Authors: Kemp Graham J. , Meyerspeer Martin , Moser Ewald 
Published: July 2007

Abstract31P MRS offers a unique view of muscle metabolism in vivo, but correct quantification is important. Inter‐study correlation of estimates of [Pi] and [phosphocreatine (PCr)] in a number of published studies suggest that the main technical problem in calibrated 31P MRS studies is the measurement of PCr and Pi signal intensities, rather than absolute quantification of [ATP]. For comparison, we discuss the few published biopsy studies of calf muscle and a selection of the many studies of quadriceps muscle. The ATP concentration is close to the value that we obtained in calf muscle in our own study, presented here, on four healthy subjects, by localised 31P MRS using a surface coil incorporating an internal reference and calibrated using an external phantom. However, the freeze‐clamp biopsy PCr concentration is ∼20% lower than the value obtained by 31P MRS, consistent with PCr breakdown by creatine kinase during freezing. Finally, we illustrate some consequences of uncertainty in resting [PCr] for analysis of mitochondrial function from PCr kinetics using a published 31P MRS study of exercise and recovery: the lower the assumed resting [PCr], the lower the absolute rate of oxidative ATP synthesis estimated from the PCr resynthesis rate; in addition, the lower the assumed resting [PCr], or the higher the assumed [total creatine], the higher the apparent resting [ADP], and therefore the more sigmoid the relationship between the rate of oxidative ATP synthesis and [ADP]. Correct quantification of resting metabolite concentrations is crucially important for this sort of analysis. Our own results ([PCr] = 33 ± 2 mM, [Pi] = 4.5 ± 0.2 mM, and [ATP] = 8.2 ± 0.4 mM; mean ± SEM) are close to the overall mean values of the 10 published studies on calf muscle by ‘calibrated’ 31P MRS (as in the present work), and of [PCr] and [Pi] in a representative selection of ‘uncalibrated’ 31P MRS studies (i.e. from measured PCr/ATP and Pi/ATP ratios, assuming a literature value for [ATP]). Copyright © 2007 John Wiley & Sons, Ltd.
Improved Reconfiguration Algorithm for the Dual Ring Network by Token Reversal
Authors: Chakraborty Rabindra Nath , Yaprak Ece 
Published: July 2007

AbstractAn improved algorithm is proposed to further enhance the reliability of the dual‐ring network over the existing reconfiguration algorithm in the case of topological alteration due to link failures. The improvement is caused by accommodating the reversal of token flow instead of the loopback operation.
Applying simulation to network planning and design issues
Authors: Jazwinski Andrew , Laszakovits Brian 
Published: July 2007

AbstractWhat is simulation good for and how do you use it? Simulation can be applied to a wide variety of network planning and design issues. This paper describes a number of such issues of interest, suggesting the most relevant simulated performance and the benefits derived from a simulated network performance analysis and then demonstrates the simulation technology through a detailed case study using Plan NetTM.
Connectionless service in an atm‐based network
Authors: Killat U. 
Published: July 2007

AbstractWith the advent of connection‐oriented broadband in the B‐ISDN, the question arises as to how can computers, founding their communication needs on MAC service, profit from the new communication infrastructure? This paper describes the answers by the CCITT to this question and outlines some of the problems to be overcome. Finally, new attempts for the provision of the Connectionless Service are presented.
Empowering Net Ware With REXX
Authors: Shepherdson Lew 
Published: July 2007

AbstractUntil now, the full power and flexibility of Net Ware could only be exploited by skilled C programmers using very non‐trivial software development kits with compilers, linkers and debuggers specifically engineered to run under Net Ware. This all changed with the recent addition of REXX into the Net Ware toolkit, which provides administrators, power users, and application developers with access to all the power of Net Ware.
Private and Authentic Communication in Passive Optical Networks
Authors: Heister U. , Killat U. 
Published: July 2007

AbstractBroadband access systems based on Passive Optical Networks (PONs) present a cost‐effective alternative to star‐shaped ones. An inherent weakness of PONs lies in their tree topology. This article identifies the measures necessary to support private and authentic two‐way communication via a passive tree.
Information networks awareness and utilization issues: The case of gulfnet
Authors: Taher Hasan , Bakry Saad Haj , Al‐Dhalaan Abdullah , Al‐Muammar Abdulaziz 
Published: July 2007

AbstractThis article addresses the awareness promotion‐utilization of services problem within the framework of the diffusion of innovation theory, and with respect to information networks, specifically in the case of GULFNET
Recent progress in research and development of crystalline silicon solar cells in Japan
Authors: Saitoh Tadashi , Shimokawa Ryuichi , Hayashi Yutaka 
Published: July 2007

AbstractRecently, the research and development of crystalline silicon solar cells in Japan has greatly advanced. Fundamental research has been conducted on the recombination and passivation of minority carriers at Si/SiO2 interfaces and in those bulk regions containing grain boundaries. Qualities of silicon feedstock and substrates have been improved and large‐area cell efficiencies using Czochralski single and cast polycrystalline substrates have reached 20% and 17%, respectively, by using low‐cost cell fabrication processes. Such high efficiency values are realized by tenacious improvement of substrate quality and the development of new processes for fabricating solar cells.
Solar cell efficiency tables
Authors: Green Martin A. , Emery Keith 
Published: July 2007

AbstractOne regular feature planned for Progress in Photovoltaics is the publishing of solar cell and module efficiency tables summarizing the highest independently confirmed results for different technologies. These tables are expected to be of interest not only to researchers directly involved in these areas but also to those less directly involved but interested in being kept informed of the latest results with each of the different technologies or interested in an authoritative summary of these results. Other desirable outcomes may be the encouragement of research results and the further simulation of intercomparison of measurements between disignated cell test centres. Guidelines for inclusion of results into these tables are outlined and the first set of tables of results conforming to these guidelines are published.
Recent progress in thin‐film cadmium telluride solar cells
Authors: Chu Ting L. , Chu Shirley S. 
Published: July 2007

AbstractCadmium telluride (CdTe) with a room‐temperature bandgap energy of 1.45 eV has been shown to be the most promising low‐cost, thin‐film photovoltaic material for terrestrial applications. Significant progress has been made during the past several years, and thin‐film CdTe solar cells of > 1 cm2 area with conversion efficiencies higher than 12% have been prepared by several techniques. Thin‐film CdTe photovoltaic modules with 10% efficiency have also been produced. They are of the heterojuntion configuration using a transparent conducting semiconductor (TCS) as the window and p‐CdTe as the absorber. In this paper, the potential window materials for thin‐film CdTe solar cells are discussed. Thus far, cadmium sulphide (CdS) with a bandgap energy of 2.42 eV at room temperature has been found to be best suited for efficient CdTe solar cells. the deposition techniques for p‐CdTe films capable of producing efficient solar cells, including close‐spaced sublimation (CSS), electrodeposition, screen printing and spraying, are briefly reviewed, and the characteristics of the resulting solar cells are discussed. It is concluded that the efficiency of thin‐film CdTe solar cells can be increased to 18‐19% in the near‐term, leading to 15‐16.5% efficient modules.
The ‘Alpsolar’ Project—Field testing and optimization of European photovoltaic power plant equipment at high‐elevation and nordic sites
Authors: Nentwich A. , Szeless A. 
Published: July 2007

AbstractThe ‘Alpsolar’ Project, which forms part of the international European ‘Eureka’ programme, is a cooperative venture between three electrical power utilities based in Austria, Finland and Germany. Its main task is the field testing and optimization of remote‐controlled, grid‐connected, photovoltaic (PV) power plants at high‐elevation and nordic sites, with the aim of bringing such plants to commercial viability. This paper describes the background, overall deisgn and operation of the three plants, and reports initial operating experience over 1‐3‐year periods in the areas of solar module, inverter and plant efficiencies; plant availability and electricity yield; monitoring and control; maintenance and repair; and economics.
The role of silicon solar cell fabrication in intermediate‐level PV training
Authors: Marques F. C. , Chambouleyron I. 
Published: July 2007

AbstractAppropriate regionally‐based training is of major importance for improving the market penetration of basic PV systems in developing countries. This communication describes an initiative at a Brazilian university where science and engineering undergraduates are encouraged to fabricate, test, and package crystalline silicon solar cells.
Phased development of high‐concentration photvoltaic modules
Authors: McNaughton W. P. , Cummings R. D. , Dostalek F. J. , Richman R. H. 
Published: July 2007

AbstractDuring the 1970s and early 1980s a promising solar cell technology evolved under contract with the Electric Power Research Institute. the work produced a point‐contact photovoltaic cell technology that has established a numer of world record achievements during its 15‐year development. In 1984 a conceptual design was proposed for a cell package, module and array system for use in utility‐scale commercial power production.Since 1984 the laboratory concept has been moved forward toward commercial application. the design and processing of the cell has progressed from laboratory device research toward a mass‐produced product, with concurrent reduction in cost and improvement in uniformity. A number of inadequacies have been confronted and eliminated.A progressive design philosophy for the production of cell packages, modules and arrays has been invoked and implemented. an extensive test programme to determine module and array performance and reliability has been put in place. More than 2500 functional high‐concentration cells have been produced in the evolutionary process. Approximately 800 of those cells have been installed in fully operational modules for filed tests. Over 130 modules have been constructed and are in field testing for electrical, structural, thermal or weathering tests. Two full‐sized array structures (each containing 60 instrumented ‘thermal’ modules) have been constructed and continue to undergo field testing for alignment, performance and reliability.This paper reviews the design, construction and testing of modules, which is a part of the programme that has been central to the overall commercialization effort. the progressive module philosophy is reviwed and key challenges that have confronted the development of a commercial system are discussed. Results are included from more than 6 years of testing, including over 250 000 h of field exposure on individual test modules and over 2 000 000 exposure hours on all modules in the prgramme.
An energy consumption scenario for sizing rural electrification PV systems
Authors: Eyras J. R. , Lorenzo E. 
Published: July 2007

AbstractThis paper submits a systematic analysis of user consumption patterns of several photovoltaic (PV)‐powered rural dwellings in a Mediterranean area of Spain. the measurements have been carried out within the framework of two projects and assessed in contrast with other experiences. This analysis allows a consumption scenario developed previsouly to be tested by means of the classification of families according to the number and age of their members into three types—extended, mean and reduced—with the aim of establishing a few standard cases of optimization for sizing purposes.Because the use of AC current is indispensable, at least for domestic appliances, the scenario hereby proposed leads to PV system sizes of 160, 320 and 480 Wp for reduced, mean and extended families, respectively, enjoying a level of comfort similar to grid‐conneced systems.
Evaluation of the steady‐state photocarrier grating technique with respect to A‐Si: H and its application to A‐Si1–X GeX: H alloys
Authors: Abel C.‐D. , Bauer G. H. 
Published: July 2007

AbstractThe steady‐state photocarrier grating technique is analysed with respect to deviations from local charge neutrality. We present a generalized expression for the normalized photoresponse β as a function of the grating period as well as of the external electric field; the transport is characterized in the sense of bipolar and ambipolar, diffusion and drift displacement, respectively. Experimental data for undoped a‐Si: H, especially the variation of the β coefficient with the external electric field, are discussed and fitted by the generalized equation. the effective dielectric relaxation time, which takes the trapped photogenerated majority carriers into account, is found to be responsible for ambipolar transport in undoped a‐Si: H in the low electric field regime. Further, the μτ‐products of electrons and holes in a‐Si1‐x Gex: H alloys are deduced experimentally. the low‐gap alloys are an appropriate candidate for photovoltaic applications.
Computer simulation of enhanced output from bifacial photovoltaic modules
Authors: Chieng Y. K. , Green M. A. 
Published: July 2007

AbstractA bifacial photovoltaic module can collect not only the light falling directly on its front but also light incident on its rear after reflection from natural surroundings, called the albedo reflection, and light scattered from the sky itself. the benefits of such bifacial response are analysed by modifying a standard computer photovoltaic simulation software package (PVFORM version 3.3). Results obtained from computer simulation and field experiments show that, without any special features, there is about a 20% increase in the total annual energy generated by a bifacial panel compared to a monofacial panel. There are also summer peaks caused by the morning and evening light falling directly on the rear side of the panel. This means that the bifacial panel allows extended operation during summer. There is also a slightly smaller reduction in relative output power for the bifacial module on cloudy days.
Optimization of decentralized hybrid electrical energy systems (with photovoltaics) for typical villages in the North Indian plains
Authors: Sodha M. S. , Chandra Ram , Rana Santosh 
Published: July 2007

AbstractThis paper presents an analysis of an optimal decentralized mix of photovoltaics, biogas generation and biomass gasifier generation, to meet the electrical energy demand of typical villages in the North Indian plains. the optimal mix preserves existing patterns of fertilizer application and cooking and also corresponds to minimum cost. Survey data for four villages have been used for a numerical appreciation of the results. It is seen that the optimal energy strategy consists of meeting as much demand as possible by biogas generators using dung and meeting the rest of the demand by an optimal combination of biomius gasifier generation and photovoltaics. the cost of electrical energy with such decentralized systems lies between Rs. 2.2 per k Wh and Rs. 8.9 per k Wh for different villages (US $1 = Rs. 30). It is seen that locally availble fuel (dung and agricultural waste) is insufficient for electrical generation and the balance has to be met by photovoltaics. Rising electrical demand in coming years means that pliotovoltaics will be an increasingly important component of such optimal systems.