Mesh size effect in numerical simulation of blast wave propagation and interaction with structures

Numerical method is popular in analysing the blast wave propagation and interaction with structures.However,because of the extremely short duration of blast wave and energy trans-mission between different grids,the numerical results are sensitive to the finite element mesh size.Previous numerical simulations show that a mesh size acceptable to one blast scenario might not be proper for another case,even though the difference between the two scenarios is very small,indicating a simple numerical mesh size convergence test might not be enough to guarantee accu-rate numerical results.Therefore,both coarse mesh and fine mesh were used in different blast scenarios to investigate the mesh size effect on numerical results of blast wave propagation and interaction with structures.Based on the numerical results and their comparison with field test re-sults and the design charts in TM5-1300,a numerical modification method was proposed to correct the influence of the mesh size on the simulated results.It can be easily used to improve the accu-racy of the numerical results of blast wave propagation and blast loads on structures.     

Effect of Shock Wave on Fabricated Anti-Blast Wall and Distribution Law Around the Wall Under Near Surface Explosion

The loads of shock wave effect on fabricated anti-blast wall and distribution law around the wall were investigated by using near surface explosion test method and FEM.The pressure-time histories and variety law on the foreside and backside of the anti-blast wall were adopted in the tests of variety of different explosion distances and dynamites,as well as in the comparison between the test and numerical calculation.The test results show that the loads of shock wave effect on the anti-blast wall were essen-tially consistent with calculation results using criterion under surface explosion when explosion distances exceed 2 m,the distribution of overpressure behind wall was gained according to variety law based on small-large-small.It is also demonstrated that the peak overpressure behind wall had commonly appeared in wall height by 1.5--2.5 multiples,and the peak overpressures of protective building behind wall could be reduced effectively by using the fabricated anti-blast wall.     

萃取水回收应用控制系统设计

萃取回收应用控制系统,充分利用萃取水中单体资源,保护生态环境,合理自动补充、分配回收水,增加经济效益,减轻工人劳动强度,控制回收水溢出污染环境。     

一维高低不对称方势阱问题的数值方法

给出了一维高低不对称方势阱中束缚态粒子的能级的数值解法和归一化波函数，所得结果在势趋于无穷大时与无限深势阱的结果一致。     

Development of Instrument Control System Using Biosignals Created by the Change of Eyes Movement Sequence

Inthe 196 0′stheUSAirForcedidextensivere searchesontheno handscontrolforpilotsusingbrainwaves.Theseresearcheswerenotworkedoutbecausethehumanbrainelectricalactivitywasundetectablysmall[1] .Forinstance ,Yogaadeptsandotherdisciplinedmedita torscangofromanalertstatetothemeditative“Alpha”statethroughchangingelectroencephalogram(EEG)fromthemostlyirregularandhigherfrequencyfluctuationstothelargelystablewaveoutputaround 10Hz,butittakeseventhebestpractitionersseveralsecondstoperform .Al thoughso…     

波的图像所反映出的一系列问题

对中学物理教学中波动图像所反映出的物理问题进行归纳总结。     

同轴线系统中电磁参数的测试

随着介质材料在电子领域的广泛应用,准确了解电磁参数值,对判断介质材料在电磁场中的效应是必要的.测试系统主要是采用波导测试系统样品进行测试,并用MATLAB软件编程实现介电常数的数学计算,用VB编程语言进行接口的控制.通过样品的多次测量证明了理论推导的正确性.     

正交试验法提取云南大花红景天中的红景天苷和酪醇

在超声波作用下，用甲醇浸提，从云南大花红景天中提取红景天苷和酪醇，以红景天苷和酪醇的转移率为评价指标，利用正交试验L16（4^5）筛选出最佳的提取条件为：提取温度65℃，提取时间15min，90％甲醇或无水甲醇和1：20料液比，按最佳提取条件，实验6次，红景天苷和酪醇的质量分数分别达到0．56g／mg和0.15g／mg，相对标准偏差为2．56％和3．52％．     

关于阴尼电磁振荡实验的研究

运用电磁理论和电路分析,阐述了串联RLC电路的暂态过程与相关结论,提出了阻尼电磁振荡次数的计算公式和振荡仪的设计方案,解决了阻尼电磁振荡仪与学生实验的设计、装备与实验问题。     

相位共轭波与简并四波混频的探析

研究了相位共轭波间的根本特点 ,于理论上分析了三阶非线性电极化效应———四波混频产生相位共轭波的原理