一种嵌入式软件逻辑覆盖测试方法研究

针对嵌入式软件测试覆盖率低的问题,本文提出了基于软件故障注入的逻辑覆盖测试方法,首先就嵌入式系统常用传感器建立故障模式库,设计了嵌入式软件故障注入系统;其次选取中间层作为故障注入点,研究基于VxWorks653嵌入式操作系统的故障注入实现方式,并通过分析故障信号在软件系统中的传播,提出优化测试用例的方法;最后通过实验验证了该方法可有效提高容错设计功能、冗余设计功能、故障检测功能测试的逻辑覆盖率;有助于提高嵌入式软件的可靠性。     

流动注射催化光度法测定痕量亚硝酸根的研究

基于亚硝酸根在酸性条件下,对溴酸钾氧化尼罗蓝褪色反应有催化作用这一原理,建立了高灵敏测定痕量亚硝酸根的流动注射结合分光光度新方法。方法的线性范围为0.008—0.3μg/mL,检出限为0.02μg/mL。利用该方法对几种河水水样进行测定,结果满意。     

简易毛细管气相色谱冷柱头进样法

介绍了一种在无冷柱头进样器和特殊注射器情况下简便可行的冷柱头进样技术。以海洛因、秋水仙碱、正三十烷醇为研究对象，考察了本方法的定性、定量偏差，提出两种溶质聚焦方法。     

流动注射化学发光法测定盐酸曲普利啶

在碱性溶液中,N-氯代丁二酰亚胺可以氧化二氯荧光素产生化学发光。盐酸曲普利啶的存在可以显著地增强这一反应的化学发光信号。基于此,结合流动注射技术,优化了实验条件,建立了测定盐酸曲普利啶的流动注射化学发光新方法。该方法测定盐酸曲普利啶的线性范围1.0×10^-9—1.0×10^-7g/mL,检出限为5.0×10^-10g/mL。对浓度为7.0×10^-9g/mL盐酸曲普利啶溶液进行11次平行测定的相对标准偏差为4.1%。该方法已用于药物制剂中盐酸曲普利啶的含量测定,结果令人满意。     

YBCO薄膜中自旋极化准粒子的注入效应

采用Nd0 .7Sr0 .3MnO3/SrTiO3/YBa2 Cu3O7-δ的异质结构 ,研究了自旋极化准粒子的注入效应 .在 5 6 μm宽的YBCO膜条上成功地制备了与超导膜条同样宽度但不同长度的六个注入结区 ,长度L分别为 80 μm ,4 0 μm ,2 0 μm ,10 μm ,5 μm和 2 μm .80nm厚的YBCO薄膜在 16K温度下Jc 为 2× 10 5A/cm2 .Iin=0 .5mA的自旋电流注入下 ,随L从 80 μm逐渐顺次减小时 ,注入效率 η =ΔJc/ΔJin逐渐增大 .而当L≤ 2 0 μm后 ,η不再增加 ,达到几乎相同的值 (～ 6 ) .初步分析认为这与自旋极化准粒子在超导膜内的有效自旋扩散长度有关 .异质结构中YBCO薄膜的超导电性以及注入窗口的尺寸对获得大的自旋注入效率十分重要 .     

微型超高压宝石喷嘴内部的空化与磨损

宝石喷嘴是影响超高压水射流切割系统工作效率的重要部件,而宝石内部的空化直接影响射流的形成,也是宝石磨损的重要原因之一。对400 MPa压力范围内宝石孔内部的空化两相流进行了数值模拟,阐述了射流在宝石内的形成过程,分析了长径比、压力和入口形状对宝石内空化的影响,并在相应压力下对宝石喷嘴的磨损进行了实验研究。结果表明:宝石内部的空化发展程度随着长径比的增大而减弱;在一定的长径比范围内,空化可以发展到喷嘴出口,并最终使射流的初始直径小于喷嘴直径,且在此条件下当压力升高时,射流的初始直径增大;良好的入口形线可以降低空化的发展程度;宝石入口的磨损较出口更显著,空蚀和高压水的冲蚀造成了宝石孔边缘形状的破坏,这种破坏随着压力的升高而加剧,选择合适的长径比是减少冲蚀磨损的有效途径。     

Injection moulding of thermoplastics. I. Freezing-off at gates

The injection moulding of thermoplastics involves, during mould filling, flow of a hot molten polymer into a mould network, the walls of which are so cold that the polymer freezes on them. During the constant pressure drop part of the filling stage, but not during the preceding constant flow-rate part, freezing-off, that is premature blockage of the mould network by frozen polymer, is possible. A semi-quantitative analysis of such freezing-off at a gate is presented here. The length-scales and time-scales of all the relevant physical processes occurring during freezing-off are identified and a criterion is obtained which enables the occurrence of freezing-off to be predicted, at least crudely. a _j constant - b _jk constant - Br Brinkman number - Br ₀ initial Brinkman number - Gz Graetz number - Gz ₀ initial Graetz number - h _c half-height of flat cavity - h _g half-height of flat gate - h _g ^* half-height of polymer melt region in flat gate - L _c length of cavity - L _f filled length - L _g length of gate - m viscosity shear-rate exponent - P pressure drop - Q volumetric flow-rate - r radial coordinate in round gate and cavity - R _c radius of round cavity - R _g radius of round gate - R _g ^* radius of polymer melt region in round gate - Sf Stefan number - t time - t _f freeze-off time - T temperature - T _i inlet polymer melt temperature - T _m melting temperature of polymer - T _w gate wall temperature - u _r radial velocity in round gate - u _x axial velocity in flat gate - u _y transverse velocity in flat gate - u _z axial velocity in round gate - w _c width of flat channel - w _g width of flat gate - x axial coordinate in flat gate and cavity - y transverse coordinate in flat gate and cavity - z axial coordinate in round gate and cavity - thermal conductivity of molten polymer - thermal conductivity of frozen polymer - heat capacity of molten polymer - heat capacity of frozen polymer - _h ratio of half-height of flat gate to that of flat cavity - _R ratio of radius of round gate to that of round cavity - _w ratio of width of flat gate to that of flat cavity - dimensionless axial coordinate in round gate and cavity - dimensionless transverse coordinate in flat gate and cavity - ^* dimensionless half-height of polymer melt region in flat gate - dimensionless temperature - _i dimensionless inlet temperature - _j j-th term in power series expansion of dimensionless temperature - thermal diffusivity ratio - dimensionless filled length - latent heat of fusion of polymer - µ viscosity - µ ₀ unit shear-rate viscosity - v _j j-th eigenvalue - j-th zero of zeroth-order Bessel function of first kind - dimensionless axial coordinate in flat gate and cavity - _c dimensionless pressure drop in cavity - _g dimensionless pressure drop in gate - density of molten polymer - density of frozen polymer - dimensionless radial coordinate in round gate and cavity - ^* dimensionless radius of polymer melt region in round gate - dimensionless time - _f dimensionless freeze-off time - ₀ dimensionless time at start of final phase of freezing-off - rescaled dimensionless time - rescaled dimensionless freeze-off time - rescaled dimensionless time at start of final phase of freezing-off - dimensionless similarity variable - dummy variable - scaled dimensionless axial coordinate in gate     

Freezing-off in disc cavities

A semi-quantitative analysis is presented of freezing-off in a disc cavity during the injection moulding of thermoplastics. A criterion is obtained which enables the occurrence of freezing-off to be predicted, at least crudely. The form of the criterion is found to depend on the direction of flow (radially outward or inward) in the disc.     

Large-Scale Streamwise Vortices in the Supersonic Part of a Permeable Nozzle

Large-scale streamwise vortices in the vicinity of a perforated wall in the supersonic part of the nozzle are studied. The governing effect of gas inflow through a perforated wall on origination and parameters of streamwise vortices is experimentally established.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 5, pp. 68–75, September–October, 2005.     

采用NND方法计算三维喷管气流场

本文运用NND显式差分格式,计算了三维喷管气流场。气流场计算的基本方程为一般贴体坐标系下三维守恒型的欧拉方程。采用了时间分裂法和Steger-Warming矢通量分裂技术。在喷管内沿周向的每个由轴线和壁面构成的子午面上根据泊松方程生成贴体网格。本文运用三维程序计算了轴对称JPL喷管,同时与实验结果和前人采用轴对称二维程序所计算的结果做了对比。最后,本文还计算了三维矢量喷管,计算结果与现有的实验结果一致。通过轴对称JPL喷管和三维矢量喷管的计算考核,表明建立的算法和编写的计算程序是正确的。文中提出了采用子午面形式的贴体网格时奇性轴的处理方法。计算结果表明在喷管壁面处,马赫数与压强的计算结果与实验值吻合较好,而在喷管轴线处,只有当网格较密时,才能得出与实验结果接近的计算结果。