曲率半径对环形聚能装药侵彻深度的影响

模拟了5种不同曲率半径ASC射流成型与侵彻半无限靶的过程,提出了ASC射流侵彻“三区域”理论,定义了ASC切割能力;研究结果表明:ASC在不同的位置具有不同的射流成型状况和靶板侵彻深度;不同曲率半径ASC侵彻深度均呈现明显区域特征,分别为曲率敏感区、稳定侵彻区、侵彻加强区;稳定侵彻区“平台高度”可作为ASC切割能力,但应高度重视小曲率半径ASC曲率敏感区侵彻深度;本模型中,曲率半径ρ大于80 mm时,ASC切割能力为稳定侵彻区“平台”高度26.5 mm.     

高温下TATB基钝感炸药爆轰波波阵面曲率效应实验研究

为了研究高温环境对钝感炸药爆轰波波阵面曲率效应的影响,采用高速扫描照相技术及电探针测速技术获取了高温60℃环境下TATB基钝感炸药三种直径药柱爆轰波拟定态爆轰波形状及波速。结果表明,TATB基钝感炸药在高温60℃下的拟定态爆轰波波速随着炸药直径基本呈现线性增长趋势,且相同直径的高温结果均低于常温结果。三种直径TATB基钝感炸药在高温60℃下的拟定态波阵面形状较常温结果更为陡峭。采用遗传算法对三种直径炸药的实验结果进行拟合计算,获得了TATB基钝感炸药高温曲率效应D_n(κ)关系参数。采用DSD(Detonation Shock Dynamics)方法对三种直径炸药的爆轰波非理想传播过程进行了模拟,计算结果与实验结果吻合较好。     

Low temperature coefficient and low line sensitivity subthreshold curvature-compensated voltage reference

A high-order curvature-compensated subthreshold voltage reference is proposed in this paper. The proposed curvature-compensated voltage reference consists of two supply-independent first-order voltage references and a curvature compensation circuit. The supply-independent first-order voltage reference uses a negative feedback loop which improves the line sensitivity and eliminates the demand of operational amplifier, whereas the curvature compensation circuit provides high-order temperature-compensated output reference voltage. The proposed curvature-compensated voltage reference provides an output reference voltage of 118.54 mV with a temperature coefficient of 21.5 ppm/°C over a wide temperature range of −60°C to 120°C . The power supply rejection ratio and line sensitivity are observed as −68.64 dB (for the frequency range of 1 Hz to 100 Hz) and 0.035%/V (for the supply voltage varies from 0.85 V to 2.5 V), respectively. The values of output noise at the frequencies of 1 kHz and 10 kHz without using any capacitive filter are obtained as 179.13 nV/ √ Hz and 123.87 nV/ √ Hz , respectively.     

塑性铰区采用FRC柱试验研究及正截面承载力分析

采用简化的纤维增强混凝土应力应变关系,根据截面变形的平截面假定和截面力的平衡方程,推导出塑性铰区采用纤维增强混凝土柱在不同极限状态时的曲率。根据各极限状态点曲率,求得截面上各分布力,对截面形心轴取距,到塑性铰区采用FRC柱的开裂、屈服、峰值和极限点的弯矩表达式。与试验结果对比表明,计算值与试验值吻合较好。     

基于BP网络识别框架结构损伤的研究

基于模态振型,提出一个新的参数——振型曲率比,作为BP网络的输入向量,然后用有限元分析计算结果作为网络的学习和预测样本,对不同的结构模拟损伤进行了识别,结果表明该方法简便有效,值得推广应用。     

预应力混凝土连续箱梁底板崩裂破坏的机理及其对策

对某主跨为85 m预应力混凝土连续箱梁桥的合龙段底板崩裂情况进行了调查与分析,运用BAP、ANSYS等有限元软件进行了仿真模拟,分析了箱梁底板混凝土崩裂的机理,并提出了处理类似问题的对策.     

Geometrical characterization of fluorescently labelled surfaces from noisy 3D microscopy data

Modern fluorescence microscopy enables fast 3D imaging of biological and inert systems alike. In many studies, it is important to detect the surface of objects and quantitatively characterize its local geometry, including its mean curvature. We present a fully automated algorithm to determine the location and curvatures of an object from 3D fluorescence images, such as those obtained using confocal or light‐sheet microscopy. The algorithm aims at reconstructing surface labelled objects with spherical topology and mild deformations from the spherical geometry with high accuracy, rather than reconstructing arbitrarily deformed objects with lower fidelity. Using both synthetic data with known geometrical characteristics and experimental data of spherical objects, we characterize the algorithm's accuracy over the range of conditions and parameters typically encountered in 3D fluorescence imaging. We show that the algorithm can detect the location of the surface and obtain a map of local mean curvatures with relative errors typically below 2% and 20%, respectively, even in the presence of substantial levels of noise. Finally, we apply this algorithm to analyse the shape and curvature map of fluorescently labelled oil droplets embedded within multicellular aggregates and deformed by cellular forces.     

PCO低渗透砂岩油藏裂缝特征综合描述

阿根廷PCO油田VOA1油藏为中孔、超低渗的砂泥岩薄互层砂岩储集层,油藏圈闭是单一大型鼻状构造。通过综合分析岩心资料、构造演化、地震曲率属性、蚂蚁追踪属性及油藏圈闭高部位纯油区内部部分井初产高含水的异常响应数据等资料,对构造裂缝的岩心直观特征、构造应变、空间分布范围和几何特征、动态开启机理等进行了综合描述。研究表明,综合地质、地震、生产等资料从多个角度描述裂缝特征及其相关性,可靠性高,可以大大降低单一方法描述裂缝的不确定性,为生产方案调整提供了有效保障。     

管状带式输送机弯曲段曲率半径的确定

通过分析,提出确定管状带式输送机弯曲段曲率半径的方法,为管状带式输送机弯曲段线路布置设计提供理论依据。     

克林根贝格螺旋锥齿轮齿面修正的数学模型

通过对螺旋锥齿轮副啮合性能及特点分析和讨论,指出了克林根贝格(Klingelnberg)齿制的齿形特征和切齿原理的特殊性。在运用齿轮啮合原理的基础上,建立克林根贝格(Klingelnberg)齿制局部共轭齿面修正的数学模型。