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31.
应用高精度的CE/SE方法对厂房中爆炸冲击波扫过障碍物挡墙形成的流场进行了二维数值模拟,具体分析了障碍物、厂房内壁与冲击波相互作用的规律,得到了能够反映障碍物作用前后波系结构变化的压力等值线图.数值结果显示了冲击波遇障碍物发生反射、绕流等现象,形成复杂波系;通过与尤障碍物存在的爆炸流场对比,分析了相对于爆点不同位置的障碍物对爆炸流场的影响;最后改变爆点个数,对爆炸流场的变化做了进一步分析.数值模拟结果符合相关物理规律. 相似文献
32.
Protel 99SE是进行印制电路板设计的首选软件。目前对该课程的教学而言,实操要求性强和课时分配少之间的矛盾成为其现存的主要矛盾。应用任务驱动法进行Protel 99SE的教学,可以在有限的教学时间内让学生更熟练地掌握该软件在实践中的应用。 相似文献
33.
用守恒元和解元法数值模拟二维溃坝洪水波 总被引:9,自引:1,他引:8
本文采用守恒元和解元方法(简称CE/SE法)来求解二维浅水方程,该方法从守恒积分型方程出发,严格遵守物理意义上的守恒律,通过设立守恒元和解元,从而提出一种新的数值模拟方法。用该方法计算得到的全溃的溃坝洪水波的数值解和理论解与文献中的实验值符合的较好。在此基础上,进一步对二维局部溃坝洪水波的演进过程进行模拟,结果表明,CE/SE法精度较高,稳定性较好,其溃坝洪水波的间断具有很高的分辨率,能很好的模拟溃坝洪水波的运动过程。 相似文献
34.
The RAISE language,method and tools 总被引:1,自引:0,他引:1
Mogens Nielsen Klaus Havelund Kim Ritter Wagner Chris George 《Formal Aspects of Computing》1989,1(1):85-114
This paper presents the RAISE1 software development method, its associated specification language, and the tools supporting it. The RAISE method enables the stepwise development of both sequential and concurrent software from abstract specification through design to implementation. All stages of RAISE software development are expressed in the wide-spectrum RAISE specification language. The RAISE tools form an integrated tool environment supporting both language and method.The paper surveys RAISE and furthermore, more detailed presentations of major RAISE results are provided. The subjects of these are (a) an example of the use of the RAISE method and language, and (b) a presentation of the mathematical semantics of the RAISE specification language. 相似文献
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为解决常规深度学习方法检测轮毂内部缺陷存在模型尺寸大、参数多和精度低等问题,提出一种轻量化YOLOv4的轮毂内部缺陷检测算法。该算法采用MobileNetV3替换YOLOv4的主干特征提取网络,并利用深度可分离卷积模块对YOLOv4的PANet(path aggregation network)模块中的传统卷积进行了替换。同时,在PANet特征加强网络中加入通道注意力机制(SE)模块,提高了轮毂内部缺陷目标的识别精度。测试结果表明,所提算法检测精度为90.23%,权值文件为45.2 MB,检测速率为68.38帧/s。相较于常规模型性能有所提升,更适用于轮毂内部缺陷的快速、准确检测。 相似文献
37.
石墨烯因具备宽波段高透光性和良好的导电性而有望成为光学窗口的电磁屏蔽材料。采用AuCl3掺杂方式增加少层石墨烯薄膜的载流子浓度,降低表面电阻值。并通过拉曼光谱对掺杂前后石墨烯薄膜进行表征、对比,得到石墨烯薄膜层数、缺陷、掺杂类型及连续性方面的信息。利用各向异性介质的平面波传输线模型,着重考虑化学势对石墨烯电导率的影响,得到宽波段掺杂石墨烯的屏蔽效能曲线。实验采用屏蔽室法对转移在PET表面的石墨烯薄膜进行屏蔽效能测试,结果表明寡层(1~2层)掺杂石墨烯的平均屏蔽效能在6.7dB左右,与计算值符合较好。 相似文献
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39.
High resolution petrophysical analyses were carried out on Urgonian (Lower Cretaceous) carbonates from outcrops in Provence, SE France. Porosity and permeability were measured on 541 plug samples selected from grain‐supported carbonates analogous to those in the age‐equivalent Shu'aiba and Kharaib Formation reservoirs in the eastern Arabian Plate. The sampling strategy allowed property heterogeneities from centimetre to kilometre scales to be investigated, as well as correlations between porosity and permeability in several different reservoir rock types. Property spatial modelling sensitivity analyses were also undertaken. The relative abundance of microporosity, grain size and sedimentary‐diagenetic anisotropy were the main geological parameters which controlled the petrophysical characteristics of the grainstones studied. Increasing microporosity decreased permeability but resulted in an increase in the homogeneity of the reservoir rocks and therefore in their predictability. An increase in grain size, from fine sand to gravel, and in the amount of intergranular pores, enhanced permeability significantly but resulted in a decrease in the homogeneity (and therefore predictability) of the reservoir rock. At a plug scale, poro‐perm relationships are very good and can be used predictively for fine grainstones dominated by microporosity; but relationships are moderate to weak for coarse rudstones with mixed pore types, including intraskeletal pores. In grainstone units, weak sedimentary anisotropy, such as decametre‐scale cross‐bedding, did not prevent the prediction of the horizontal property distribution from vertical data over a few hundreds of metres. In these units, the lateral correlation of rock properties follows periodic variograms with a 7 m wavelength. The lateral distribution of properties in coarse‐grained and heterogeneous rudstones with complex pore types and intense sedimentary heterogeneities, such as channel structures, was however more difficult to predict from a vertical data set. Upscaling poroperm data from plug scale to reservoir scale is linear in the case of grainstones with intergranular microporosity, but is non‐linear in the case of skeletal rudstones with coarser pore types including skeletal porosity. 相似文献
40.
Growth of hydrogenated amorphous silicon in a doping inversed silicon heterojunction solar cell (n-a-Si:H/i-a-Si:H/p-c-Si) interface was investigated by High Resolution Transmission Electron Microscopy (HR-TEM), Spectroscopic Ellipsometry (SE), Fourier Transform Infrared Attenuated Total Reflection spectroscopy (FTIR-ATR) and current–voltage (I–V) measurements. Effective Medium Approximation (EMA) to the SE was used to describe breakage of epi-Si and evolution of mixture of microcrystalline and amorphous phases. Fabricated silicon heterojunction solar cells were characterized by dark and light I–V measurements at Standard Test Conditions. By improving the cleaning and deposition conditions, solar cells with 9.2% efficiency over 72 cm2 total active area were obtained on p-type c-Si wafers. 相似文献