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IEEE Symposium on Nuclear science (NSS/MIC)

作者： L. Ramello C. Avila D. Bollini A.E.C. Rodriguez C.C. Sanchez W. Dabrowski A.D. Garcia M. Gambaccini P. Giubellino P. Grybos J.L. Gaitan A. Marzari-Chiesa L.M. Montano F. Prino J.C. Sanabria A. Sarnelli K. Swientek A. Taibi A. Tuffanelli P. Van Espen P. Wiacek Dipartimento Scienze e Tecnologie Avanzate Università del Piemonte Orientale Alessandria Italy Universidad de Los Andes Bogota Colombia Dipartimento di Fisica Università del Piemonte Orientale Bologna Italy CEA DEN Havana Cuba Faculty of Physics and Applied Computer Science AGH University of Science and Technology Cracow Poland Dipartimento di Fisica INFN Università di Ferrara Ferrara Italy Dipartimento di Fisica Sperimentale INFN Università di Torino Torino Italy CINVESTAV Mexicali Mexico Department of Chemistry University of Antwerp Antwerp Belgium

We present results obtained with a single photon counting system of 384 silicon microstrips (100 micron pitch) equipped with six RX64DTH ASICs including charge preamplifier, shaper, two discriminators and two 20-bit counters for each channel. The energy resolution of the system was determined to be of 0.72 keV (rms) with a spread of threshold setting of 0.32 keV for the whole 384-channel module (at energies of 29-33 keV), indicating its excellent potential for dual-energy imaging. Images of a mammographic test object made of PMMA, polyethylene and water were taken in scanning mode (strips parallel to incoming X-rays) under the dual energy X-ray beams. Images were subsequently processed with the dual energy subtraction technique (Alvarez and Macovski, 1976). Experimental results agree well with MCNP simulations of the mammographic phantom and demonstrate the capability of our system to obtain contrast cancellation between two kinds of materials, thereby enhancing the visibility of small features in the third material.

关键词： Silicon Microstrip Application specific integrated circuits Mammography X-rays Preamplifiers Counting circuits Energy resolution Optical imaging Testing

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Raman scattering investigation of a Ge/SiO2/Si nanocrystal system under hydrostatic pressure

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Physical Review B 2004年第12期69卷 125333-125333页

作者： Lei Liu K. L. Teo Z. X. Shen J. S. Sun E. H. Ong A. V. Kolobov Y. Maeda Physics Department Blk. S12 Faculty of Science National University of Singapore 2 Science Drive 3 117542 Singapore Department of Electrical and Computer Engineering National University of Singapore 4 Engineering Drive 3 117576 Singapore Mechatronics & Micro System Group Data Storage Institute 117608 Singapore Center for Applied Near-Field Optics Research (CANFOR) National Institute of Advanced Industrial Science and Technology Tsukuba Central 4 1-1-1 Higashi Tsukuba Ibaraki 305-8562 Japan Department of Energy Science and Technology Kyoto University Sakyo-ku Kyoto 606-8501 Japan

We have studied the hydrostatic pressure dependence of Ge nanocrystals embedded in a SiO2 matrix on a Si substrate by Raman scattering at room temperature. During the first cycle of increasing pressure, we observed a step change in the Ge Raman mode from 310.4 to 313.8cm−1 at ∼23kbar. The linear pressure coefficients α obtained before and after the step change at ∼23kbar are 0.42 and 0.64cm−1kbar−1, respectively. Upon decreasing pressure, the Ge mode follows a single slope of pressure coefficient α=0.64cm−1kbar−1. A finite-element analysis was carried out to investigate the elastic-field distribution in the Ge/SiO2/Si nanocrystal system, where the discontinuity of the specific geometric configuration with different elastic constants causes local areas of stress concentration around the interface. The step change of the Raman shifts with pressure at ∼23kbar was attributed to complete delamination between the SiO2 film and the Si substrate.

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Numerical Investigation of Boson-Fermion Stars in Dilatonic Gravity

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Journal of Computational Methods in sciences and Engineering 2002年第1-2期2卷 245-252页

作者： Boyadjiev, T.L. Todorov, M.D. Fiziev, P.P. Yazadjiev, S.S. Faculty of Mathematics and Computer Science University of Sofia Sofia Bulgaria Faculty of Applied Mathematics and Computer Science Technical University of Sofia Sofia Bulgaria Faculty of Physics University of Sofia 5 james bourcheir Blvd. Sofia1164 Bulgaria

We investigate numerically models of static spherically symmetric boson-fermion stars in the scalar-tensor theory of gravity with a massive dilation field. The proper mathematical model of such stars is interpreted as a nonlinear two-parametric eigenvalue problem with an unknown internal boundary. To solve this problem, the Continuous Analogue of Newton Method (CANM) is employed. On each iteration CANM leads to two separate linear boundary value problems with different dimensions inside and outside the star. Along with them a nonlinear algebraic system for the spectral parameters is also solved. In this way, we determine the behaviour of the basic geometric quantities and functions describing the dilation field and matter fields building the star. Prom the physical point of view, the main result is that the structure and properties of such stars depend essentially both on their fermionic and bosonic components. © 2001 IOS Press.

关键词： Newton-Raphson method

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Modeling of TED of boron in the underlying silicon layer due to boron implantation

Modeling of TED of boron in the underlying silicon layer due...

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2002 5th IEEE International Conference on Semiconductor Electronics, ICSE 2002

作者： Norfaezah Sabki, S. Hashim, M.R. Aziz, Azlan A. Asbbum, P. Solid State and Applied Physics Group School of Physics University Sains Malaysia 11800 Penang Malaysia Dept. of Electronics and Computer Science Faculty of Engineering University of Southampton United Kingdom

ISBN: (纸本)0780375785

Ion implantation's high selectivity played a very important role in forming active device region and low resistance ohmic contact for bipolar and CMOS transistors. However the process of annealing for dopant activation and repair, problems related to anomalous transient enhanced diffusion (TED) negate the benefits of ion implantation. The irregular dopant diffusion makes the realization of sharp and shallow junction devices difficult. It is therefore very important to model the TED in relation to the implantation energy before any realistic design of the transistor can be made. In this work, both experimental result from special structures with different implantation energies and process simulator SILVACO SILVACO is studied and used to model TED. © 2002 IEEE.

关键词： Ion implantation

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Collaborative simulation grid: Multiscale quantum-mechanical/classical atomistic simulations on distributed PC clusters in the US and Japan

Collaborative simulation grid: Multiscale quantum-mechanical...

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2002 IEEE/ACM Conference on Supercomputing, SC 2002

作者： Kikuchi, Hideaki Kalia, Rajiv K. Nakano, Aiichiro Vashishta, Priya Iyetomi, Hiroshi Ogata, Shuji Kouno, Takahisa Shimojo, Fuyuki Tsuruta, Kenji Saini, Subhash Computer Science Department Department of Materials Science Department of Physics and Astronomy Department of Biomedical Engineering University of Southern California United States Concurrent Computing Laboratory for Materials Simulations Department of Computer Science Department of Physics and Astronomy Louisiana State University United States Department of Physics Niigata University Japan Department of Applied Sciences Yamaguchi University Japan Faculty of Integrated Arts and Sciences Hiroshima University Japan Department of Electrical and Electronic Engineering Okayama University Japan IT Modeling and Simulation NASA Ames Research Center United States

ISBN: (纸本)076951524X

A multidisciplinary, collaborative simulation has been performed on a Grid of geographically distributed PC clusters. The multiscale simulation approach seamlessly combines i) atomistic simulation based on the molecular dynamics (MD) method and ii) quantum mechanical (QM) calculation based on the density functional theory (DFT), so that accurate but less scalable computations are performed only where they are needed. The multiscale MD/QM simulation code has been Grid-enabled using i) a modular, additive hybridization scheme, ii) multiple QM clustering, and iii) computation/communication overlapping. The Gridified MD/QM simulation code has been used to study environmental effects of water molecules on fracture in silicon. A preliminary run of the code has achieved a parallel efficiency of 94% on 25 PCs distributed over 3 PC clusters in the US and Japan, and a larger test involving 154 processors on 5 distributed PC clusters is in progress. © 2002 IEEE.

关键词： Density functional theory

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Texpro-The educational computer program for the modeling of textiles properties

Texpro-The educational computer program for the modeling of ...

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IMEKO TC1 Symposium on Education in Measurement and Instrumentation 2002: Challenges of New Technologies

作者： Konecki, Wlodzimierz Department of Textile Metrology Faculty of Textiles Engineering and Marketing Technical University of Lódź Zeromskiego str. 116 Lódź90-543 Poland Faculty of Technical Physics Computer Science and Applied Mathematics Technical University of Lódź Wólczańska str. 216 Lódź90-543 Poland

The new worked-out computer program, named TEXPRO, for modeling of textiles properties is presented. The program is written in C++ language and built in form of handbook divided into particular exercises. It is design... 详细信息

ISBN: (纸本)9781634391801

关键词： Textiles

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Modeling of TED of boron in the underlying silicon layer due to boron implantation

Modeling of TED of boron in the underlying silicon layer due...

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IEEE International Conference on Semiconductor Electronics (ICSE)

作者： S.N. Sabki M.R. Hashim A.A. Aziz P. Ashburn Solid State and Applied Physics Group School of Physics Universiti Sains Malaysia Penang Malaysia Department of Electronics and Computer Science Faculty of Engineering University of Southampton UK

关键词： Boron Silicon Ion implantation Implants Annealing Semiconductor device modeling Semiconductor process modeling physics Epitaxial layers Solid state circuits

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Time-frequency analysis of a complicated Doppler signal with two figure eight kernels

Time-frequency analysis of a complicated Doppler signal with...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

作者： Y. Noguchi F. Matsumoto E. Kashiwagi K. Watanabe S. Sugimoto Department of Applied Physics National Defense Academy Yokosuka Japan Department of Computer Science National Defense Academy Yokosuka Japan Engineering Shonan Insitutute of Technology Fujisawa Japan Faculty of Engineering Shohnan Institute of Technology Fujisawa Japan

A Cohen's class time-frequency analysis has high resolution on the TF plane both in time and in frequency. A complicated (nonstationary and/or nonlinear) Doppler signal was obtained from synthesized data. In order to analyze this signal, two kinds of figure eight kernels were used:(1) a figure eight kernel, and (2) a 2nd figure eight kernel. As well known conventional kernels, we used a Wigner kernel, and a Choi-Williams kernel. Using our figure eight kernels, the original signal was demodulated with high resolution. Furthermore, a 2nd figure eight kernel improved the demodulation accuracy.

关键词： Time frequency analysis Kernel Signal analysis Iron Signal resolution Harmonic analysis Doppler shift Design methodology physics computer science

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Time-frequency analysis of a noisy ultrasound Doppler signal with a 2nd figure eight kernel

Time-frequency analysis of a noisy ultrasound Doppler signal...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

作者： Y. Noguchi E. Kashiwagi K. Watanabe F. Matsumoto S. Sugimoto Department of Applied Physics National Defense Academy Yokosuka Japan Department of Computer Science National Defense Academy Yokosuka Japan Faculty of Engineering Shohnan Institute of Technology Fujisawa Japan

Nonstationary ultrasound Doppler signals, those are changing with time and frequency simultaneously, are widely observed in biological and speech signals. A Cohen's class time-frequency (TF) analysis can analyze nonstationary signals with high resolution in time and frequency at a same time. A time-frequency distribution (TFD) is largely affected by a kernel function. Thus, there is sometimes a case where auto-terms (those are signal components) are covered by cross-terms (those are spurious components). In order to apply TFDs to a nonstationary and nonlinear Doppler ultrasound signals, experimental data were obtained by moving a steel ball to and fro by continuously irradiating it with ultrasound in olive oil. The movement of the steel ball was controlled by various functions. To analyze these signals, four kernels were used: (1) a Wigner kernel, (2) a Choi-Williams kernel, (3) a figure eight kernel, and (4) a 2nd figure eight kernel. Using our 2nd figure eight kernel, the demodulation accuracy was improved even with noise.

关键词： Time frequency analysis Noise figure Ultrasonic imaging Kernel Signal analysis Steel Speech Signal resolution Petroleum Demodulation

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Scalable Atomistic Simulation Algorithms for Materials Research 01

Scalable Atomistic Simulation Algorithms for Materials Resea...

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2001 ACM/IEEE Conference on Supercomputing, SC 2001

作者： Nakano, Aiichiro Kalia, Rajiv K. Vashishta, Priya Campbell, Timothy J. Ogata, Shuji Shimojo, Fuyuki Saini, Subhash Concurrent Computing Laboratory Materials Simulations Biological Computation and Visualization Center Department of Computer Science Department of Physics and Astronomy Louisiana State University United States Logicon Inc. Naval Oceanographic Office Major Shared Resource Center Department of Applied Sciences Yamaguchi University Japan Faculty of Integrated Arts and Sciences Hiroshima University Japan It Modeling and Simulation Nasa Ames Research Center

ISBN: (纸本)158113293X

A suite of scalable atomistic simulation programs has been developed for materials research based on space-time multiresolution algorithms. Design and analysis of parallel algorithms are presented for molecular dynamics (MD) simulations and quantum-mechanical (QM) calculations based on the density functional theory. Performance tests have been carried out on 1,088-processor Cray T3E and 1,280-processor IBM SP3 computers. The linear-scaling algorithms have enabled 6.44-billion-atom MD and 111,000-atom QM calculations on 1,024 SP3 processors with parallel efficiency well over 90%. The production-quality programs also feature wavelet-based computational-space decomposition for adaptive load balancing, spacefilling-curve-based adaptive data compression with user-defined error bound for scalable I/O, and octree-based fast visibility culling for immersive and interactive visualization of massive simulation data. © 2001 ACM.

关键词： Density functional theory

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