Teaching A level physics through microcomputer dynamic modelling: Evaluation of teaching

Abstract  This paper describes an evaluation of teaching A level Physics through dynamic modelling. This teaching was carried out with a group of 12 lower sixth Nuffield A level Physics students and was evaluated with three tests internal to the school and with the external public Nuffield A level Physics (NAP) examination which those students later took. The internal school tests showed that the treatment group performed better than an equivalent non-treatment group in both general ability and in a few particular skills. The public NAP examination showed no superiority of the treatment group, but indicated a significant preference for an optional question that involved mathematical skills, even though none of the treatment group took mathematics at A level. Comments are made about the educational significance of dynamic modelling and about computers in education generally.     

Three-step concept (TSC) in modeling microelectronics reliability (MR): Boltzmann–Arrhenius–Zhurkov (BAZ) probabilistic physics-of-failure equation sandwiched between two statistical models

When encountering a particular reliability problem at the design, fabrication, testing, or an operation stage of a product’s life, and considering the use of predictive modeling to assess the seriousness and the likely consequences of the a detected failure, one has to choose whether a statistical, or a physics-of-failure-based, or a suitable combination of these two major modeling tools should be employed to address the problem of interest and to decide on how to proceed. A three-step concept (TSC) is suggested as a possible way to go in such a situation. The classical statistical Bayes’ formula can be used at the first step in this concept as a technical diagnostics tool. Its objective is to identify, on the probabilistic basis, the faulty (malfunctioning) device(s) from the obtained signals (“symptoms of faults”). The recently suggested physics-of-failure-based Boltzmann–Arrhenius–Zhurkov’s (BAZ) model and particularly the multi-parametric BAZ model can be employed at the second step to assess the remaining useful life (RUL) of the faulty device(s). If the RUL is still long enough, no action might be needed; if it is not, corrective restoration action becomes necessary. In any event, after the first two steps are carried out, the device is put back into operation (testing), provided that the assessed probability of its continuing failure-free operation is found to be satisfactory. If the operational failure nonetheless occurs, the third, technical diagnostics step should be undertaken to update reliability. Statistical beta-distribution, in which the probability of failure is treated as a random variable, is suggested to be used at this step. While various statistical methods and approaches, including Bayes’ formula and beta-distribution, are well known and widely used in numerous applications for many decades, the BAZ model was introduced in the microelectronics reliability (MR) area only several years ago. Its attributes are addressed and discussed therefore in some detail. The suggested concept is illustrated by a numerical example geared to the use of the prognostics-and-health-monitoring (PHM) effort in actual operation, such as, e.g., en-route flight mission.     

高通量工程试验堆堆芯物理量的简易估算

文中通过一些有效近似,根据单群中子模型建立了计算堆芯初始有效增殖系数、元件燃耗、元件热中子积分通量和元件积分功率等物理量的计算公式。     

乙醇柴油混合燃料的应用研究

5％～15％乙醇柴油混合燃料在18℃以上不用助溶剂也可形成稳定期较长的混合燃料制品，而添加适当的助溶剂使EIO及E15可以在较低温度下保持长期稳定不分层。E10及E15的理化性质与普通柴油接近，柴油机动力性能下降幅度不大，油耗增加不多，排气烟度却有明显的改善。     

聚丙烯物理改性探讨

对目前广泛采用的增强、填充改性聚丙烯(PP)作了初步的探讨,通过PP中不同含量的GF增强剂、测出了其部分机械性能的值,从理论上和实验中得出了PP的机械性能最优时GF增强剂.     

RCS－Ⅰ反应堆堆芯模拟程序

本文介绍堆芯三维物理—热工水力耦台计算程序ＲＣＳ－Ｉ（ＲｅａｃｔｏｒＣｏｒｅＳｉｍｕｌａｔｏｒ）．其中子学模型采用先进的粗网格节块格林函数法，热工水力计算模型采用于通道分析方法．通过考虑多种反馈，该程序比较真实地描述堆芯的燃耗过程，具有临界、燃耗、中毒、跟踪和倒料等多种功能，可用于动力堆和研究堆的设计．     

How symbolic computation boosts productivity in the simulation of partial differential equations

While there have been considerable efforts over the past 30 years to improve productivity in scientific computation through the creation of subroutine libraries, much of the mundane, error-prone work in developing simulation codes has remained. This situation has spurred the development of specialized efforts in both the numerical and symbolic computation domains. For instance, numerical software like PDECOL, L1SODE, and UNPACK will solve large classes of partial differential equations, ordinary differential equations, and linear equations, respectively. On the symbolic side of this issue, a few basic tools for developing simulation codes were created by Wirth in the late 1970s. We introduce more advanced uses of symbolic techniques, including two strategies that link the symbolic and numeric computing approaches in the context of simulation codes.     

铀氢锆堆物理计算及燃料管理软件包

建立了一套铀氢锆堆物计算软件包，首先考虑氢化锆中的热化特殊性，按ＷＭＳ格式制作 了氢化锆 氢的６９群群常数并入ＷＩＭＳ－Ｄ／４数据库中，形成了ＷＩＭＳ－Ｎ１库和ＷＩＭＳ－Ｎ２库；应用ＷＩＭＳ－Ｎ２库和国际通用的ＷＩＭＳ－Ｄ／４程序包计算了铀氢锆堆各类栅元的群常数，应用差分程序ＣＩＴＡＴＩＯＮ和六角形节块和ＳＩＸＴＵＳ进行扩散计算，同时在ＳＩＸＴＵＳ－２程序的基础上编制了燃料管理程序和ＸＰＲ－ＩＣＦ     

The changes produced in the electrical resistance of vacuum-condensed films of neodymium and praseodymium when they react with hydrogen and with air

When thin films of vacuum-condensed praseodymium and neodymium are exposed to hydrogen or to air the electrical resistance changes owing to the chemical reactions which occur. The progress of the reactions was studied by means of the resistance changes which occur and by means of electron diffraction.At room temperature, neodymium reacted less readily with hydrogen than did praseodymium and the reaction rate for both metals increased with increasing temperatures. The phases formed in the various experiments ranged from the double h.c.p. structure of the metals to the high resistance cubic structure of the hydrides LnH_x with x approaching 3. Cubic and hexagonal Nd₂O₃ formed when the specimens were strongly heated by the beam of the electron microscope.Exposure to air caused the films to oxidize. Thin films approximately 250 Å thick became insulators but the oxide layer formed on thicker films protected the interior of a given film from rapid oxidation so that the film did not become an insulator.     

Structural,electrical and optical properties of r.f.-magnetron-sputtered SnO2:Sb film

The effects of gas composition, pressure and substrate temperature on the properties of relatively thick (0.2–0.8 μm) SnO₂ films deposited onto fused quartz substrates by r.f. magnetron sputtering are reported. The lowest resistivity of about 2 × 10^?3ωcm was attained for high rate deposition conditions of about $\text{1000}\text{A}\text{?}\text{min}{}^{\mathrm{?1}}$ on substrates at a temperature of 400°C in an atmosphere of 10% O₂. This value corresponds to a carrier density of 3 × 10²⁰cm^?3 and a mobility of 10 cm²V^?1s^?1. The crystal structure was found to be sensitive to all the above parameters. Low resistivity films showed a highly preferred orientation of (101) parallel to the substrate.