New computer program for three-dimensional relativistic hydrodynamical model

An effective computer program for three-dimensional relativistic hydrodynamical model has been developed. It implements a new approach to the early hot phase of relativistic heavy-ion collisions. The computer program simulates time-space evolution of nuclear matter in terms of ideal-fluid dynamics. Equations of motions of hydrodynamics are solved making use of finite difference methods. Commonly-used algorithms of numerical relativistic hydrodynamics RHLLE and MUSTA-FORCE have been applied in simulations. To speed-up calculations, parallel processing has been made available for solving hydrodynamical equations. The test results of simulations for 3D, 2D and Bjorken expansion are reported in this paper. As a next step we plan to implement the hadronization algorithm by implementing the continuous particle emission for freeze-out and comparing it with Cooper-Frye formula.     

基于图像的三维刚体运动估计算法比较

基于图像特征点对应估计三维刚体运动是计算机视觉的一个基本问题。对四种常用的运动估计算法,包括基于三维特征点的奇异值分解法、正交分解法、单位四元数法和基于二维特征点的"8点算法",通过大量仿真实验和一个机载目标运动光测系统进行了精度,稳定性和效率的比较。结论表明,基于三维特征的算法比基于二维特征的算法精度高、稳定性好,效率高。其中在基于三维特征的算法中,奇异值分解法效率更高,单位四元数法稳定性更好,在基于二维特征的算法中采用非线性优化是必须的,而增加特征点数和降低噪声水平对四种算法都能提高精度。讨论了这些结论对解决实际问题的作用。     

Design of two-dimensional zero reference codes with a genetic algorithm

In mask-alignment systems a reference signal is needed to align the mask with the silicon wafers. The optical reference signal is the autocorrelation of two two-dimensional (2D) codes with binary transmittance. For a long time, one-dimensional codes have been used in grating-measurement systems to obtain a reference signal. The design of this type of code has needed a great computational effort, which limits the size of the code to about 100 elements. Recently, we have applied genetic algorithms to design codes with arbitrary length. We propose the application of these algorithms to design 2D codes to generate 2D optical signals used in mask-alignment systems.     

3D ultrasound reconstruction algorithms from analog and digital data

Freehand 3D ultrasound is increasingly being introduced in the clinic for diagnostics and image-assisted interventions. Various algorithms exist for combining 2D images of regular ultrasound probes to 3D volumes, being either voxel-, pixel- or function-based. Previously, the most commonly used input to 3D ultrasound reconstruction has been digitized analog video. However, recent scanners that offer access to digital image frames exist, either as processed or unprocessed data. To our knowledge, no comparison has been performed to determine which data source gives the best reconstruction quality. In the present study we compared both reconstruction algorithms and data sources using novel comparison methods for detecting potential differences in image quality of the reconstructed volumes. The ultrasound scanner used in this study was the Sonix RP from Ultrasonix Medical Corp (Richmond, Canada), a scanner that allow third party access to unprocessed and processed digital data. The ultrasound probe used was the L14-5/38 linear probe. The assessment is based on a number of image criteria: detectability of wire targets, spatial resolution, detectability of small barely visible structures, subjective tissue image quality, and volume geometry. In addition we have also performed the more “traditional” comparison of reconstructed volumes by removing a percentage of the input data. By using these evaluation methods and data from the specific scanner, the results showed that the processed video performed better than the digital scan-line data, digital video being better than analog video. Furthermore, the results showed that the choice of video source was more important than the choice of tested reconstruction algorithms.     

Determination of edge correspondence using color codes for one-shot shape acquisition

A robust method for measuring 3D shapes is proposed, in which only one stripe pattern image is required. To determine edge correspondence, we match color codes instead of edge codes because the former are more stable and immune to the standard deviation of the Gaussian filter in edge detection and width of the color band. The color code is identified by K-means. This method exhibits huge advantages in adaptability and automation over thresholding techniques. The proposed decoding method is compared with two well-known algorithms, dynamic programming and multi-pass dynamic programming. Using ground truth, we evaluate the performance of the methods in measuring three different objects. Quantitative and qualitative comparisons are shown in the experiments, and results affirm that our method is effective and robust.     

基于JASMIN框架的辐射流体与粒子输运耦合计算

基于JASMIN框架的"联邦计算",将两个串行程序辐射流体RH2D与粒子输运Sn2D作为独立"邦元"耦合连接,形成的集成程序RHSn2D可以采用数千处理器并行模拟多物理耦合问题.集成程序RHSn2D中的邦元具有各自独立的网格划分与并行算法,同时借助框架技术,可以屏蔽邦元间的并行数据传递.算例表明,对于应用问题规模(90 720个网格单元,辐射流体100个Patch,粒子输运2 835个Patch,Sn方向48,16群),集成程序RHSn2D采用1 024个处理器可以达到36%的并行效率.     

对称能密度依赖的输运理论模型研究中的一些问题的讨论

本文非常简要地介绍了目前通过重离子碰撞中的对称能敏感观测量获取对称能密度依赖的研究现状,讨论了在输运理论模型计算中可能引起计算结果的不确定性的几个问题。特别与目前广泛采用的输运理论模型计算相关的3个方面的问题,即对称势动量依赖项和中子、质子有效质量劈裂;不同电荷态△产生的阈能和相关截面的介质修正;输运理论模型中的多体关联和涨落等的处理等问题。     

Solution of Quantum Mechanical Problems Using Finite Element Method and Parametric Basis Functions

New computational schemes, symbolic-numerical algorithms and programs implementing the high-accuracy finite element method (FEM) for the solution of quantum mechanical boundary-value problems (BVPs) are reviewed. The elliptic BVPs in 2D and 3D domains are solved using the multivariable FEM and Kantorovich method using parametric basis functions. We demonstrate and compare the efficiency of the proposed calculation schemes, algorithms, and software by solving the benchmark BVPs that describe the scattering on a barrier and a well, the bound states of a helium atom, and the quadrupole vibration in a collective nuclear model.     

Multidimensional Particle Codes: Their Capabilities and Limitations for Modeling Space and Laboratory Plasmas

Increasing the number of dimensions calls for significant changes in simulation techniques. Demand on computer time and space increases by orders of magnitude, and hardware development affects the feasibility. Gridless and Fokker-Planck codes are possible in one dimension but one needs grids and PIC codes in two and three dimensions. This imposes limits on Debye lengths, particle size and spacing, and resolution. Nonspectral (local) electromagnetic (EM) codes also suffer a Courant restriction on ?t, in addition to the usual ?p?t restriction. Spectral methods therefore have an advantage: they also permit convenient filtering, particle shaping, and control of resolution. Two-dimensional and 2?D codes are well advanced and documented [4], [5]. Three-dimensional codes are in their infancy. Data management, rather than physics or numerical analysis, becomes the major problem [10]. Machine-independent 3D codes are too limited in resolution and speed. Parallelism helps greatly but makes the 3D codes machine dependent. A present-day limit is attempted in a 2*128**3 grid code for CRAY's which processes ~5 million particles in ~2 min per time step. Layering is employed to break up the 3D problem into many 2D problems. Fields and particles are packed and buffered in and out of core. Diagnostics are limited by the large volume of information accumulated in a run. Results of runs with 3D codes have tended to show that the third dimension, treated as "ignorable" in 2D simulations, should not have been ignored.     

Efficient spectral and pseudospectral algorithms for 3D simulations of whistler-mode waves in a plasma

Efficient spectral and pseudospectral algorithms for simulation of linear and nonlinear 3D whistler waves in a cold electron plasma are developed. These algorithms are applied to the simulation of whistler waves generated by loop antennas and spheromak-like stationary waves of considerable amplitude. The algorithms are linearly stable and show good stability properties for computations of nonlinear waves over tens of thousands of time steps. Additional speedups by factors of 10–20 (comparing single core CPU and one GPU) are achieved by using graphics processors (GPUs), which enable efficient numerical simulation of the wave propagation on relatively high resolution meshes (tens of millions nodes) in personal computing environment. Comparisons of the numerical results with analytical solutions and experiments show good agreement. The limitations of the codes and the performance of the GPU computing are discussed.     

On the extended depth of focus algorithms for bright field microscopy

Microscopes offer a limited depth of focus which precludes the observation of a complete image of a three-dimensional (3D) object in a single view. Investigations, by a variety of researchers, have led to the development of extended depth of focus algorithms for serial optical slices of microscopic 3D objects in recent years. However, to date, no quantitative comparison of the different algorithms has been performed, generally leaving the evaluation to the subjective qualitative appreciation of the observer. In this paper we use three different tests for extended depth of focus algorithm evaluation and test 10 different algorithms, some of them have been adapted (by us) for a series of optical slices. However, the main contribution of the paper is a new improved algorithm for computing the extended depth of focus.     

半导体多物理效应并行计算程序JEMS-CDS-Device设计与实现

针对复杂电磁环境下器件多物理效应机理研究需求,研发了半导体多物理效应并行计算程序JEMS-CDS-Device。介绍了JEMS-CDS-Device的架构设计与实现技术。程序基于非结构网格并行框架JAUMIN实现,采用有限体积法(FVM)离散,使用牛顿法全耦合求解"电-载流子输运-热"问题。程序采用"内核+算法库"形式架构,支持2维和3维非结构网格、千万自由度问题并行求解,支持物理方程、离散算法、材料物理模型等的扩展开发。     

Comparison between numerical models for radiative transfer simulation in the atmosphere-ocean system

An extensive comparison between radiative transfer codes in the atmosphere-ocean system is proposed and performed. The full angular radiance distribution at several optical depths in atmosphere and water is intercompared on a set of idealized problems designed to study codes’ accuracy in modeling separate, specific system features. In-water profiles of upwelling nadir radiance, upwelling and downwelling irradiance are intercompared for a realistic case extracted from an experimental data set. Two models are involved: the FEM numerical algorithm, based on the finite element method, and the PHO-TRAN 3D backward Monte Carlo code. The results show an optimal agreement between the codes under any condition. Codes’ relative differences are always lower than the estimated statistical error on the PHO-TRAN results.     

Full-scale mathematical model for describing the temperature conditions of a reactor of the RBMK type in the case of an accident with complete deenergization

This paper describes a full-scale mathematical model used for the analysis of temperature conditions of an RBMK nuclear reactor in the event of its complete deenergization. The results of the verification and some computational results are presented.     

TREND code for reconstruction of neutron reaction cross sections and calculation of the Doppler broadening in the region of resolved resonances

The TREND code is developed for reconstruction of neutron cross sections in the region of resolved resonances from the data of the international evaluated nuclear data libraries using the Reich-Moore, Adler-Adler, and Breit-Wigner formalisms and for calculation of the Doppler broadening of the resulting cross sections within the classical approximation. The TREND code is incorporated into the MCU code package for Monte Carlo reactor calculations. The TREND and MCU codes have been used to evaluate the data of the ROSFOND data bank on uranium and plutonium isotopes in comparison with the data of the ICSBEP data bank.     

组件计算程序PANDA研发及初步验证

PANDA是上海核工程研究设计院研发的压水堆组件计算程序。该程序采用基于特征线方法（MOC）的一步化计算流程,即在不引入能群压缩和栅元均匀化的情况下直接进行组件层面的两维非均匀输运计算。多群数据库采用基于ENDF/B-VI制作的70群结构中子数据库,基于ENDF/B-VII的新版数据库也正在开发中。共振自屏计算采用了空间相关丹可夫方法（SDDM）,既具备燃料芯块分区计算的能力,又保留了传统Stammler方法的计算效率。多群非均匀输运计算采用二维模块化MOC方法,并辅以双重粗网有限差分(CMFD)加速技术,具有良好的计算精度和效率。对传统线性子链解析（TTA）方法以及多种矩阵指数方法进行了研究,选取了适合PANDA程序燃耗链的燃耗方程求解技术。基于以上基本模型开发了PANDA程序,并从程序模块、总体集成和核设计程序系统确认等三个层面,初步验证了PANDA程序的计算性能,表明了PANDA程序的工程设计计算能力。     

Testing a spatial model of the spectral radiance of combustion product plumes

The results of testing of the Plume-2D-MC and Plume-3D-MC computer codes for calculating the spectral radiance (signature) of combustion product plumes and various gas volumes with light-scattering particles and for predicting the degree of attenuation of this emission by atmospheric gases at a great distance away. These codes are based on various algorithms for modeling the characteristic of radiative heat transfer and various models of the thermal radiation of hot gases (the NASA IR radiation model, HITRAN and CDSD-1000 databases, and statistical models of wide and narrow bands). These codes were used to simulate experimental data on the spectral radiance of hot gases.     

Radiation effect of neutrons produced by D–D side reactions on a D–3He fusion reactor

One of the most important characteristics in D–³He fusion reactors is neutron production via D–D side reactions. The neutrons can activate structural material, degrading them and ultimately converting them into high-level radioactive waste, while it is really costly and difficult to remove them. The neutrons from a fusion reactor could also be used to make weapons-grade nuclear material, rendering such types of fusion reactors a serious proliferation hazard. A related problem is the presence of radioactive elements such as tritium in D–³He plasma, either as fuel for or as products of the nuclear reactions; substantial quantities of radioactive elements would not only pose a general health risk, but tritium in particular would also be another proliferation hazard. The problems of neutron radiation and radioactive element production are especially interconnected because both would result from the D–D side reaction. Therefore, the presentation approach for reducing neutrons via D–D nuclear side reactions in a D–³He fusion reactor is very important. For doing this research, energy losses and neutron power fraction in D–³He fusion reactors are investigated. Calculations show neutrons produced by the D–D nuclear side reaction could be reduced by changing to a more ³He-rich fuel mixture, but then the bremsstrahlung power loss fraction would increase in the D–³He fusion reactor.     

Calculated and experimental characteristics of a scroll machine operating in the air motor mode

The results of mathematical modeling, numerical experiments, and full-scale tests of a scroll machine operating in the air motor mode are presented. The mechanical and discharge characteristics, as well as values of the mechanical and exergetic efficiencies, have been obtained for different supply pressures. The high energy efficiency of the scroll motor under consideration in comparison to other types of air (pneumatic) motors is demonstrated.