检索结果-内蒙古大学图书馆

Conference on Quantum Information and Computation iii

作者： Cabral, GEM Lula, B de Lima, AF Univ Fed Campina Grande BR-58109970 Campina Grande PB Brazil

ISBN: (纸本)0819458007

current technology for building digital computers is predicted to reach its limit within the next 10 years due to the increasing miniaturization of digital components. By reaching sizes of a few nanometers, electrons stop behaving as particles and start behaving as waves, obeying essentially the principles of Quantum Mechanics, and effects such as interference, superposition and entanglement become dominant. The utilization of those effects allows more that just an evolution of the miniaturization process. It allows for a computational parallelism impossible to be obtained efficiently through classical computational methods or devices. Several algorithms utilizing such effects have been proposed and indicated that Quantum Computation is significantly more efficient at solving certain class of problems than classical computation. Actually, there is not yet any hardware (a quantum computer) able to compute a useful algorithm outside of research labs. A turn-around to that problem is to simulate the behavior of a quantum computer by a classical computer. There are, to this day, a number of quantum computer simulators available which, in general, use the quantum circuit model defined by Deutsch. Just a few of them are universal. We have developed a novel universal quantum circuit simulator, called Zeno, to the design and test of quantum algorithms. Zeno offers a set of features that engulfs most of the features presented by the other existing universal quantum circuit simulators and that also allows it to be used in the design and simulation of quantum channels.

关键词： universal quantum simulator modeling quantum circuit quantum algorithm quantum channel

来源：评论

学校读者我要写书评

暂无评论

FPGA design and implementation of a fast pixel purity index algorithm for endmember extraction in hyperspectral imagery

FPGA design and implementation of a fast pixel purity index ...

引用

Chemical and Biological Standoff Detection iii

作者： Valencia, David Plaza, Antonio Vega-Rodríguez, Miguel A. Pérez, Rosa M. Computer Science Department University of Extremadura Avda. de la Universidad s/n E-10071 Cáceres Spain Computer Science Department University of Extremadura Avda. de la Universidad s/n E-10071 Cáceres Spain

Hyperspectral imagery is a class of image data which is used in many scientific areas, most notably, medical imaging and remote sensing. It is characterized by a wealth of spatial and spectral information. Over the last years, many algorithms have been developed with the purpose of finding "spectral endmembers," which are assumed to be pure signatures in remotely sensed hyperspectral data sets. Such pure signatures can then be used to estimate the abundance or concentration of materials in mixed pixels, thus allowing sub-pixel analysis which is crucial in many remote sensing applications due to current sensor optics and configuration. One of the most popular endmember extraction algorithms has been the pixel purity index (PPI), available from Kodak's Research Systems ENVI software package. This algorithm is very time consuming, a fact that has generally prevented its exploitation in valid response times in a wide range of applications, including environmental monitoring, military applications or hazard and threat assessment/tracking (including wildland fire detection, oil spill mapping and chemical and biological standoff detection). Field programmable gate arrays (FPG As) are hardware components with millions of gates. Their reprogrammability and high computational power makes them particularly attractive in remote sensing applications which require a response in near real-time. In this paper, we present an FPGA design for implementation of PPI algorithm which takes advantage of a recently developed fast PPI (FPPI) algorithm that relies on software-based optimization. The proposed FPGA design represents our first step toward the development of a new reconfigurable system for fast, onboard analysis of remotely sensed hyperspectral imagery.

关键词： Algorithms

来源：评论

学校读者我要写书评

暂无评论

FPGA developments for the SPARTA project

FPGA developments for the SPARTA project

引用

Astronomical Adaptive Optics Systems and Applications II

作者： Goodsell, S.J. Fedrigo, E. Dipper, N.A. Donaldson, R. Geng, D. Myers, R.M. Saunter, C.D. Soenke, C. Centre for Advanced Instrumentation Department of Physics Durham University South Road Durham DH1 3LE United Kingdom European Southern Observatory Karl-Schwarzschild-Str. 2 D-85748 Garching bei München Germany

The European Southern Observatory (ESO) and Durham University's Centre for Advanced Instrumentation (CfAI) are currently designing a standard next generation Adaptive Optics (AO) Real-Time Control System. This platform, labelled SPARTA 'Standard Platform for Adaptive optics Real-Time Applications' will initially control the AO systems for ESO's 2nd generation VLT instruments, and will scale to implement the initial AO systems for ESO's future 100m telescope OWL. Durham's main task is to develop the Wavefront Sensor (WFS) front end and Statistical Machinery for the SPARTA platform using Field Programmable Gate Arrays (FPGA). SPARTA takes advantage of a FPGA device to alleviate the highly parallel computationally intensive tasks from the system processors, increasing the obtainable control loop frequency and reducing the computational latency in the control system. The WFS pixel stream enters a PMC hosted FPGA card contained within the SPARTA platform via optical fibres carrying the VITA 17.18/10 standard 2.5Gbps-1 serial Front Panel Data Port (sFPDP) protocol. Each FPGA board can receive a maximum of l0Gbs -1 of data via on-board optical transceivers. The FPGA device reduces WFS frames to gradient vectors before passing the data to the system processors. The FPGA allows the processors to deal with other tasks such as wavefront reconstruction, telemetry and real-time data recording, allowing for more complex adaptive control algorithms to be executed. This paper overviews the SPARTA requirements and current platform architecture, Durham's Wavefront Processor FPGA design and it concludes with a future plan of work.

关键词： Adaptive optics

来源：评论

学校读者我要写书评

暂无评论

Recent developments in superconducting cavity RF control

Recent developments in superconducting cavity RF control

引用

14th Symposium on Photonics and Web engineering

作者： Simrock, S DESY D-2000 Hamburg Germany

ISBN: (纸本)0819457566

Presently a large number of superconducting accelerators under construction or proposed impose stringent requirements on the rf control of the accelerating fields, operability, and reliability. The accelerator application range from linear colliders, UV-FELs and X-FELs, ERL based light sources, high power proton accelerators to heavy ion accelerators. Examples are TESLA and NLC, the European XFEL and Lux, the Cornell ERL based light source, the high power ERL based IR-FEL at JLAB, the neutron spallation source SNS, the heavy ion accelerator RIA, and the energy upgrade of the CEBAF accelerator at JLAB. The requirements on the rf systems range from low to high current, medium to high gradient, and relativistic to non-relativistics beam. With the technology in analog and digital electronics developing rapidly, the technology for rf feedback system is changing more and more from analog or hybrid systems towards fully digital systems. Todays DSPs and FPGAs can process sophisticated feedback algorithms on a time scale of some 100 ns to a few us with ADCs and DACs with about 100 MHz bandwidth at 14 bit and latencies less than 100 ns available to interface to the field detectors and field control actuators. Also fast analog multiplier technology allows for field detection and actuators for rf control with high linearity, measurement and control bandwidth while maintaining low noise levels.

关键词： superconducting accelerators RF system control system feedback digital signal processor field programmable array logic analog to digital converter digital to analog converter

来源：评论

学校读者我要写书评

暂无评论

Off-target model based OPC

Off-target model based OPC

引用

25th Annual BACUS Symposium on Photomask Technology

作者： Lu, Mark Liang, Curtis King, Dion Melvin iii, Lawrence S. Graduate School Chinese Academy of Sciences Beijing 100049 China Shanghai Institute of Microsystem and Information Technology CAS Shanghai 200050 China Grace Semiconductor Manufacturing Corp. 818 Guoshoujing Rd. Shanghai 201203 China Synopsys Inc. 2025 NW Cornelius Pass Road Hillsboro OR 97124 United States

Model-based optical Proximity correction has become an indispensable tool for achieving wafer pattern to design fidelity at current manufacturing process nodes. Most model-based OPC is performed considering the nominal process condition, with limited consideration of through process manufacturing robustness. This study examines the use of off-target process models - models that represent non-nominal process states such as would occur with a dose or focus variation - to understands and manipulate the final pattern correction to a more process robust configuration. The study will first examine and validate the process of generating an off-target model, then examine the quality of the off-target model. Once the off-target model is proven, it will be used to demonstrate methods of generating process robust corrections. The concepts are demonstrated using a 0.13 μm logic gate process. Preliminary indications show success in both off-target model production and process robust corrections. With these off-target models as tools, mask production cycle times can be reduced.

关键词： optical systems

来源：评论

学校读者我要写书评

暂无评论

Identifying unknown nanocrystals by fringe fingerprinting in two dimensions & free-access crystallographic databases

Identifying unknown nanocrystals by fringe fingerprinting in...

引用

Two- and Three-Dimensional Methods for Inspection and Metrology iii

作者： Moeck, Peter Čertik, Ondřej Seipel, Bjoern Groebner, Rebecca Noice, Lori Upreti, Girish Fraundorf, Philip Erni, Rolf Browning, Nigel D. Kiesow, Andreas Jolivet, Jean-Pierre Department of Physics Portland State University P.O. Box 751 Portland OR 97207-0751 United States Faculty of Mathematics and Physics Charles University of Prague Ke Karlovu 3 121 16 Praha Czech Republic Department of Physics and Astronomy Center for Molecular Electronics University of Missouri St. Louis MO 53121 United States Department of Chemical Engineering and Materials Science University of California at Davis One Shields Avenue Davis CA 95616 United States FEI Electron Optics PO Box 80066 5600 KA Eindhoven Netherlands National Center for Electron Microscopy MS 72-150 Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 United States Fraunhofer Institute for Mechanics of Materials Heideallee 19 06120 Halle Germany 75252 Paris Cedex 05 France

New needs to determine the crystallography of nanocrystals arise with the advent of science and engineering on the nanometer scale. Direct space high-resolution phase-contrast transmission electron microscopy (HRTEM) and atomic resolution Z-contrast scanning TEM (Z-STEM), when combined with tools for image-based nanocrystallography possess the capacity to meet these needs. This paper introduces such a tool, i.e. fringe fingerprinting in two dimensions (2D), for the identification of unknown nanocrystal phases and compares this method briefly to qualitative standard powder X-ray diffractometry (i.e. spatial frequency fingerprinting). Free-access crystalfographic databases are also discussed because the whole fingerprinting concept is only viable if there are comprehensive databases to support the identification of an unknown nanocrystal phase. This discussion provides the rationale for our ongoing development of a dedicated free-access Nano-Crystallography Database (NCD) that contains comprehensive information on both nanocrystal structures and morphologies. The current status of the NCD project and plans for its future developments are briefly outlined. Although feasible in contemporary HRTEMs and Z-STEMs, fringe fingerprinting in 2D (and image-based nanocrystallography in general) will become much more viable with the increased availability of aberration-corrected transmission electron microscopes. When the image acquisition and interpretation are, in addition, automated in such microscopes, fringe fingerprinting in 2D will be able to compete with powder X-ray diffraction for the identification of unknown nanocrystal phases on a routine basis. Since it possesses a range of advantages over powder X-ray diffractometry, e.g., fringe fingerprint plots contain much more information for the identification of an unknown crystal phase, fringe fingerprinting in 2D may then capture a significant part of the nanocrystal metrology market.

关键词： Crystallography

来源：评论

学校读者我要写书评

暂无评论

The growing importance of computations in materials science: current capabilities and perspectives

The growing importance of computations in materials science:...

引用

作者： Wimmer, Erich Materials Design 44 avenue F.-A. Bartholdi Le Mans 72000 France

Materials scientists are facing unprecedented challenges in a large number of areas including energy storage, microelectronics, display technologies, catalysis, and environmental degradation of structural materials, Advances in experimental methods, for example the use of synchrotron light sources and high-throughput synthesis produce massive amounts of data, which need to be interpreted. At the same time, new computational methods are being developed and the efficiency of computer hardware and software continues to increase rapidly. As a result, the importance of computational materials science is growing. Computations serve three major objectives: (i) they provide insight and allow the interpretation of experimental data, (ii) they offer guidance for new experimental efforts by computational prescreening, and (iii) they allow the prediction of materials properties, which may be difficult or even impossible to measure directly. As illustrative cases, this lecture will focus on the areas of energy storage, notably hydrogen storage materials, the environmental degradation of structural materials, microelectronic materials, and catalysis. With the calculation of phonon dispersions, which has now become possible on a routine basis for large structures, temperature dependent thermodynamic functions can be evaluated systematically. Recent results, especially for metal-hydrogen systems reveal that the electronic total energy, even if calculated at a high level of accuracy, might be insufficient to make quantitative predictions of actually measurable properties such as formation and reaction enthalpies. A critical assessment will be provided of the current capabilities of predicting structural, thermomechanical, electronic, optical, and magnetic materials properties. A perspective on current and future scientific developments, their priorities and their impact on academic and industrial research strategies will conclude this contribution.

关键词： Materials science

来源：评论

学校读者我要写书评

暂无评论

Towards automated design of quantum cascade lasers

引用

JOURNAL OF APPLIED PHYSICS 2005年第8期97卷 084506-084506页

作者： Mircetic, A Indjin, D Ikonic, Z Harrison, P Milanovic, V Kelsall, RW Univ Belgrade Fac Elect Engn YU-11120 Belgrade Serbia Univ Leeds Sch Elect & Elect Engn Leeds LS2 9JT W Yorkshire England

We present an advanced technique for the design and optimization of GaAs/AlGaAs quantum cascade laser structures. It is based on the implementation of the simulated annealing algorithm with the purpose of determining a set of design parameters that satisfy predefined conditions, leading to an enhancement of the device output characteristics. Two important design aspects have been addressed: improved thermal behavior, achieved by the use of higher conduction band offset materials, and a more efficient extraction mechanism, realized via a ladder of three lower laser states, with subsequent pairs separated by the optical phonon energy. A detailed analysis of performance of the obtained structures is carried out within a full self-consistent rate equations model of the carrier dynamics. The latter uses wave functions calculated by the transfer matrix method, and evaluates all relevant carrier-phonon and carrier-carrier scattering rates from each quantized state to all others within the same and neighboring periods of the cascade. These values are then used to form a set of rate equations for the carrier density in each state, enabling further calculation of the current density and gain as a function of the applied field and temperature. This paper addresses the application of the described procedure to the design of lambda similar to 9 mu m GaAs-based mid-infrared quantum cascade lasers and presents the output characteristics of some of the designed optimized structures. (C) 2005 American Institute of Physics.

关键词： gallium arsenide aluminium compounds iii-V semiconductors quantum cascade lasers optical design techniques simulated annealing semiconductor device models conduction bands phonons current density wave functions transfer function matrices

来源：评论

学校读者我要写书评

暂无评论

Tunnel junctions in GaN/AlN for optoelectronic applications

Tunnel junctions in GaN/AlN for optoelectronic applications

引用

Device Research Conference

作者： M.J. Grundmann J.S. Speck U.K. Mishra Electrical and Computer Engineering University of California Santa Barbara CA USA Materials Departments University of California Santa Barbara CA USA

The authors propose a new device design using the polarization properties of the iii-nitrides system that eliminates the need for high doping concentrations and has the further benefit of potentially eliminating problematic p-type contacts. P-type material in the nitrides is plagued by high contact resistance and high sheet resistance. These problems could be eliminated by contacting n-type material that acts as a current spreading layer and using a tunnel junction to transfer current to p-type material with minimal losses (Takeuchi et al., 2001)

关键词： Gallium nitride P-n junctions Doping Sheet materials Voltage Photonic band gap Contact resistance Tunneling Application software optical design

来源：评论

学校读者我要写书评

暂无评论

New developments in Gallium Nitride and the Impact on Power Electronics

New Developments in Gallium Nitride and the Impact on Power ...

引用

Annual IEEE Conference on Power Electronics Specialists (PESC)

作者： M.A. Khan G. Simin S.G. Pytel A. Monti E. Santi J.L. Hudgins Department of Electrical Engineering University of South Carolina Columbia SC USA Department of Electrical Engineering University of Nebraska Lincolnshire NE USA

Wide bandgap iii-nitride semiconductor materials possess superior material properties as compared to silicon, GaAs and other iii-V compound materials. Recent achievements in gallium nitride (GaN) technology for optoelectronics have resulted in ultra-bright blue light emitting diodes and lasers, ultraviolet emitters, and solar-blind optical detectors. In the electronic area, drastic improvement of microwave device performance has been achieved, yielding record high power densities of 20-30 W/mm. Novel applications of these materials in high-power electronics for switching, energy conversion and control are just emerging. This paper provides an overview of the state-of-the-art iii-nitride wide bandgap technologies and it explores power electronic applications while illustrating the enormous potential that GaN based devices have for overcoming the major challenges of power electronics in the 21st century. The paper discusses the unique material and device properties of GaN-based semiconductors that make them promising for high-power, high-temperature applications. These include high electron mobility and saturation velocity, high sheet carrier concentration at heterojunction interfaces, high breakdown voltages, and low thermal impedance (when grown over SiC or bulk AIN substrates). The chemical inertness and radiation hardness of nitrides are other key properties. As applied to power electronics, the Ill-Nitride technology allows for high-power switching with sub-microsecond and nano-second switching times. The paper will present the innovations that further improve the performance of high-power DC-DC converters, switches and other building blocks. These include novel insulated gate HFET design that significantly expands the allowable input voltage amplitude, further increases the device peak currents, and most importantly, tremendously improves the large-signal stability and reliability. Insulated gate switching devices have been shown to operate at up to 300 degC wit

关键词： iii-V semiconductor materials Gallium nitride Power electronics Photonic band gap Semiconductor materials optical materials DC-DC power converters Switching converters Switches Insulation

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：