存储技术的新突破——进化海量存储系统

本刊讯 由谢长生、曹强、吴非、谭志虎、万继光、黄建忠等人组成的“进化海量存储系统关键技术与实现方法”项目组针对海量网络存储系统，在数据组织方式和组织策略上提出了多项发明技术。针对存储系统物理和逻辑的组织方式是一种静态组织结构，不能很好地刻画处于不断变化之中的系统，提出了一种进化存储系统及其进化方法、自适应数据存储优化分布和存储设备数据再生进化方法，获得3项发明专利；还提出了一种存储系统数据分布及互转换和一种基于连续度聚类和时间序列的IO区域预取的方法，申请2项发明专利。针对数据存储安全性，提出了一种在内核态文件系统层的加密读写和一种用于存储系统的全局缓存管理的方法，申请2项发明专利。以上技术都已投入使用，从多角度提高了网络存储系统的性能，提供了多种关键技术缓解I／O瓶颈的方法。采用部分上述技术和方法形成的“采用零拷贝技术的多协议磁盘阵列控制器”为国内首款具有自主知识产权的磁盘阵列硬件控制器，并已成功应用于军用加固磁盘阵列和民用磁盘阵列系统中。     

统一气体动理学方法研究进展

在临近空间高超声速飞行器气动载荷、航天飞行器变轨/调姿、微尺度元器件传质/传热等科学和工程实践中，存在着大量的时序多流域（多尺度）流动问题以及位于单一流场中的复杂多流域问题（局部稀薄问题），对数值预测工作提出挑战.因此，近年来从介观气体动理学基础上发展出了一大类将连续流与稀薄流进行统一计算的高效数值方法，包括确定论形式的UGKS，GKUA和DUGKS方法，以及粒子形式的USP-BGK和UGKWP方法.文章围绕着确定论和统计粒子两类统一方法的最新研究进展进行回顾和分析，重点关注在每种方法中全流域统一性质的来源与实现方式、目前已取得的关键进展以及该方法的扩展性和应用价值.      

等离子体的SO-FDTD算法和对电磁波反射系数的计算分析

将一类色散介质的介电常数写成有理分式函数形式，进而导出FDTD中电位移矢量D和电场强度E之间的关系，形成SO-FDTD方法. 应用该方法计算了冷等离子体平板对电磁波的反射系数，通过与解析结果的比较，验证了该算法的高效性和高精度，同时，应用SO-FDTD方法，计算了等离子体层对垂直入射电磁波的反射系数，结果表明：等离子体厚度、电子密度、电子密度的分布形式和入射波频率是影响反射系数的重要因素. 关键词： 等离子体 电磁波 FDTD方法     

二维卡门涡街的格子Boltzmann仿真

格子气自动机和格子Boltzmann方法的迅速发展提供了一类求解流体力学问题的新的方法。本文中，我们介绍了Boltzmann方法，解决了格子气方法中的缺点，通过选择适当平衡分布及其参数，导出了Navier－Stokers方程，并得到了声速和粘性系数。最后在微机上模拟了在无限长平板流动问题及绕单分离板的流动问题，得到了卡门涡街。结果表该模型有格子气方法及其它的数值方法所没有的优点，计算更精确、更直观、更有效。     

基于自适应无下采样提升框架的Stokes图像获取方法

根据成像偏振探测中stokes参数图像获取的原理和方法，分析了传统求取stokes参数图像方法在保留图像细节信息和处理输入图像微小平移等方面的不足，在此基础上提出了基于自适应平移不变小波分解的stokes参数图像求取方法，并用无下采样的提升框架来执行平移不变小波分解以提高算法的灵活性和计算速度.针对不同的stokes参数图像求取方法，用均值、方差、熵、边界能量对融合结果进行评价和分析.通过仿真，表明本文方法提高了stokes参数图像的质量并改善了stokes参数图像计算方法对输入图像平移的敏感性.     

激发创新意识、培养创新思维

创造也叫创新，就是创造性地提出问题和创造性地解决问题，教育是创造的产物，创造是教育的核心，是教育的最高境界，也是教育最神圣的使命．学生的创新能力，包括多方面，就物理学科来讲，应该是通过各种基本能力（如实验能力、观察能力、分析能力、动手能力等）和各种基本方法（如假设方法、理想化方法、实验方法、类比方法、数学方法等）的综合应用，来达到创造性地提出问题和解决问题的能力．在物理教学中，根据物理学科特点，在对学生进行知识传授的同时，进行创新意识、创新思维、创新能力的培养，是非常重要的，这也是创新教育的一个…     

ICP－AES方法快速测定工业硫酸中的砷和铁含量

本文所述方法是将工业硫酸定量稀释，直接雾化进入ＩＣＰ激发，测定其中砷和铁的光谱强度和含量。绘制校准曲线用标准溶液，加入与测定样品相同量的分析纯硫酸为基体。该方法快速、简便，合成标准样品分析结果与标称值吻合，进口工业硫酸样品中砷、铁含量测定结果与国外检验结果、国家标准方法检验结果基本吻合。     

高亮度白光LED用外延片的新进展

文章首先介绍了发光二极管（LED）的内量子效率、外量子效率的基本概念和提高量子效率的基本方法，接着对LED外延的结构和方法做了简要介绍．文章的第三和第四部分则着重介绍了提高内、外量子效率的外延方法，这些方法包括外延结构的优化，侧向外延生长，SiC和GaN衬底的生长，AIInGaN四元系有源区生长，非极性面、半极性面的外延，表面粗化结构生长，图形化二次外延结构．图形化蓝宝石衬底上的外延，提高载流子注入效率的结构和组分设计．文章的第五部分则介绍了基于可靠性和成本考虑的其他新型外延结构，第六部分介绍了提高LED可靠性的外延方法．最后得出结论：采用非极性面的GaN衬底，生长优化的LED结构，并结合光子晶体技术，可望取得突破性进展．     

基于D S理论的中子测试数据统计

 针对由于样本数量、测量误差和动态特性等因素，致使采用概率统计方法来对中子发生器的中子测试数据进行统计存在许多局限性和不合理性，讨论了D-S理论中的基本分配、信任函数、上下概率等概念，利用该理论对中子发生器的中子测量数据进行处理统计，最终得到中子产额在一定置信区间内概率分布上、下限值和平均中子产额。与传统的概率统计方法相比，该统计方法能适用于非精确性数据，且不受样本大小的限制。     

一种基于密度泛函理论计算晶体结合能的变分法

提出了一种基于密度泛函理论计算晶体结合能的变分法，利用该方法初步计算了ＬｉＦ、ＮａＦ、ＫＦ、ＬｉＣｌ、ＮａＣｌ和ＫＣｌ这六种典型离子晶体的结合能、平衡晶格常数和体弹性模量，与实验结果进行了比较，分析了存在的问题，并指出了与其它同类方法相比该方法的优点     

Entropy production in the flow over a swirling stretchable cylinder

In the present work, the entropy generation due to the heat transfer and fluid friction irreversibility is investigated numerically for a three-dimensional flow induced by rotating and stretching motion of a cylinder. The isothermal boundary conditions are taken into account for the heat transfer analysis. The similarity transformations are utilized to convert the governing partial differential equations to ordinary differential equations. Resulting nonlinear differential equations are solved using a numerical scheme. Expressions for the entropy generation number, the Nusselt number and the Bejan number are obtained and discussed through graphs for various physical parameters. An analysis has been made to compare the heat transfer irreversibility with fluid friction irreversibility using the expression of the Bejan number. It is found that the surface is a durable source of irreversibility and the curvature of cylinder is to enhance the fluid friction irreversibility.     

Lattice Boltzmann simulation for hydrothermal analysis of free convection within dumbbell-shaped heat exchanger

The lattice Boltzmann simulation of nanofluid flow and heat transfer during natural convection within a dumbbell-shaped heat exchanger is carried out. The heat exchanger is filled with CuO–water. The KKL model is employed to predict the thermo-physical properties of nanofluid. In order to perform a comprehensive hydrothermal investigation, different post-processing approaches such as heatline visualization, total entropy generation, local entropy generation based on local fluid friction irreversibility and heat transfer irreversibility, average and local Nusselt variation are employed. In the present investigation, it is tried to present the impact of different influential parameters like Rayleigh number, solid volume fraction of nanofluid and thermal arrangement of internal fins-bodies on the fluid flow, heat transfer rate and entropy generation.     

Ecological optimization of an irreversible harmonic oscillators Carnot heat engine

A model of an irreversible quantum Carnot heat engine with heat resistance, internal irreversibility and heat leakage and many non-interacting harmonic oscillators is established in this paper. Based on the quantum master equation and semi-group approach, equations of some important performance parameters, such as power output, efficiency, exergy loss rate and ecological function for the irreversible quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. Effects of internal irreversibility and heat leakage on the ecological performance are discussed. A performance comparison of the quantum heat engine under maximum ecological function and maximum power conditions is also performed.     

换热器性能分析新方法

鉴于以加热或冷却为目的的热量传递过程,其不可逆性应以NFDA1的耗散率来度量,为此可以用换热器中的NFDA1耗散率定义换热器的当量热阻,它既包含换热器中的传热热阻,还包含了由非逆流形式和非平衡流引起的附加热阻. 换热器当量热阻的倒数称之为换热器的当量热导. 通过NFDA1耗散定义的换热器当量热阻建立了传热不可逆性与有效度的联系,并导得了换热器有效度与当量热导（热阻）和热容量流比的统一函数关系式,它适用于不同流程布置的换热器. 因此,有效度-热导（热阻）方法能更方便于不同类型换热器性能的分析和比 关键词： 换热器 热阻 耗散 熵产     

Entropy Generation Analysis of the Flow Boiling in Microgravity Field

Entropy generation analysis of the flow boiling in microgravity field is conducted in this paper. A new entropy generation model based on the flow pattern and the phase change process is developed in this study. The velocity ranges from 1 m/s to 4 m/s, and the heat flux ranges from 10,000 W/m² to 50,000 W/m², so as to investigate their influence on irreversibility during flow boiling in the tunnel. A phase–change model verified by the Stefan problem is employed in this paper to simulate the phase–change process in boiling. The numerical simulations are carried out on ANSYS-FLUENT. The entropy generation produced by the heat transfer, viscous dissipation, turbulent dissipation, and phase change are observed at different working conditions. Moreover, the Be number and a new evaluation number, E_P, are introduced in this paper to investigate the performance of the boiling phenomenon. The following conclusions are obtained: (1) a high local entropy generation will be obtained when only heat conduction in vapor occurs near the hot wall, whereas a low local entropy generation will be obtained when heat conduction in water or evaporation occurs near the hot wall; (2) the entropy generation and the Be number are positively correlated with the heat flux, which indicates that the heat transfer entropy generation becomes the major contributor of the total entropy generation with the increase of the heat flux; (3) the transition of the boiling status shows different trends at different velocities, which affects the irreversibility in the tunnel; (4) the critical heat flux (CHF) is the optimal choice under the comprehensive consideration of the first law and the second law of the thermodynamics.     

热机的第二定律效率与不可逆性

利用热机的功－熵关系和可用能概念，给出热机经二定律效率的表达式，同时了热机相对损失功的概念，并用它们比较了几个实际动力源的不可逆程度。     

Entropic Balance Conditions and Optimization of Distillation Column System

The paper considers the limitation problem of the distillation column systems separating multicomponent mixtures with serial and parallel structures. The solution takes into account the irreversibility of processes. Using entropic balance conditions, the dependence of load on heat consumption is obtained for a binary distillation column. This dependence is parameterized through two characteristic coefficients–reversible efficiency and irreversibility factor. This dependence was used to solve problems of distribution of heat and raw material fluxes in parallel column structure and selection of optimal separation order in serial structure. The obtained results make it possible to estimate the minimum heat consumption for the separation of a given flow of raw materials, the maximum productivity, and efficiency of the system.     

热漏、内不可逆性和导热规律对制冷机最优性能的影响

１引言有限时间热力学研究制冷循环性能已取得了一批成果。已发表了热阻加热漏模型［１－４］、热阻加内不可逆模型问研究各种损失对卡诺循环性能的影响。本文作者用一常数项ｑ表示热漏流率,用常系数表示热阻和热漏外的其余内不可逆性,建立了一类广义不可逆制冷机模型［６－７］,并分析了牛顿传热定律下的最优性能。本文将基于此模型和较为普遍的导热规律,导出制冷机的制冷率、制冷系数最佳特性关系。２广义不可逆卡诺制冷机及其最优性能考虑一类工作在两个恒温热源之间的定常态流卡诺制冷机,循环中存在热阻、热漏和其它内不可逆性［６…     

Stirling Refrigerating Machine Modeling Using Schmidt and Finite Physical Dimensions Thermodynamic Models: A Comparison with Experiments

The purpose of the study is to show that two simple models that take into account only the irreversibility due to temperature difference in the heat exchangers and imperfect regeneration are able to indicate refrigerating machine behavior. In the present paper, the finite physical dimensions thermodynamics (FPDT) method and 0-D modeling using the Schmidt model with imperfect regeneration were applied in the study of a β type Stirling refrigeration machine.The 0-D modeling is improved by including the irreversibility caused by imperfect regeneration and the finite temperature difference between the gas and the heat exchangers wall. A flowchart of the Stirling refrigerator exergy balance is presented to show the internal and external irreversibilities. It is found that the irreversibility at the regenerator level is more important than that at the heat exchangers level. The energies exchanged by the working gas are expressed according to the practical parameters, necessary for the engineer during the entire project. The results of the two thermodynamic models are presented in comparison with the experimental results, which leads to validation of the proposed FPDT model for the functional and constructive parameters of the studied refrigerating machine.     

Analytical Analysis of Heat Transfer and Entropy Generation in a Tube Filled with Double-Layer Porous Media

The heat transfer and entropy generation in a tube filled with double-layer porous media are analytically investigated. The wall of the tube is subjected to a constant heat flux. The Darcy-Brinkman model is utilized to describe the fluid flow, and the local thermal non-equilibrium model is employed to establish the energy equations. The solutions of the temperature and velocity distributions are analytically derived and validated in limiting case. The analytical solutions of the local and total entropy generation, as well as the Nusselt number, are further derived to analyze the performance of heat transfer and irreversibility of the tube. The influences of the Darcy number, the Biot number, the dimensionless interfacial radius, and the thermal conductivity ratio, on flow and heat transfer are discussed. The results indicate, for the first time, that the Nusselt number for the tube filled with double-layer porous media can be larger than that for the tube filled with single layer porous medium, while the total entropy generation rate for the tube filled with double-layer porous media can be less than that for the tube filled with single layer porous medium. And the dimensionless interfacial radius corresponding to the maximum value of the Nusselt number is different from that corresponding to the minimum value of the total entropy generation rate.