客车新型车门双螺旋减速传动装置

针对双螺旋减速传动装置的理论设计计算问题进行了研究,在利用空间几何分析法的基础上,建立了机构学模型;在讨论该装置的失效形式的基础上,给出了承载能力的计算步骤.     

结构可靠性界限计算的包络面方法

在结构二次二阶矩可靠性指标计算方法的基础上,结合包络面的思想,提出了基于包络面的结构可靠性界限计算方法。该方法在最可几失效域以旋转抛物面作为结构极限状态曲面的内外包络面,通过计算包络面的失效概率确定结构可靠性界限区间,并通过两个算例验证了该方法的可行性和计算精度。算例结果表明,该方法计算结果最接近蒙特卡洛方法的结果,相对误差小,计算精度高,具有工程实用价值。     

调节型球阀和蝶阀的选用

介绍了调节型球阀和蝶阀选用的步骤及计算中一些系数的经验取法。     

基于可靠性的连续体结构拓扑优化设计

建立水平集函数为设计变量、刚度极小化为目标、具有可靠性约束的连续体结构拓扑优化模型,并提出相应的优化算法.文中提出的基于可靠性的结构拓扑优化算法方法分为两个步骤,结构可靠性分析和结构拓扑优化.可靠性分析采用计算简便、效率高的一次二阶矩法,结构拓扑优化设计则应用稳定高效、最优结构清晰的水平集方法.最后以悬臂梁结构的可靠性拓扑优化为例,表明文中提出的方法既简单又有效.     

空间角度钻模的设计

在空间角度钻模的设计中,关键是如何计算定位角和定向角,文中总结和分析了空间角度位置的四种情况,介绍了一种简便计算方法在空间角度钻模设计中的应用.     

空间光学遥感器外遮光罩的地球反照辐射的随机模拟计算

根据概率论的基本原理,用随机模拟法对空间光学遥感器外这光罩的地球反照辐射进行了计算,有效地模拟了任意空间位置的阳光反照的定向辐射强度分布.此方法尤其适用于空间飞行器外露腔体的精确热计算.     

沙量平衡计算的时空尺度问题研究

指出了沙量平衡计算是一种探索流域泥沙运移规律的研究方法,但由于所选取的时间与空间尺度不同,将对沙量平衡计算的结果具有很大的影响,甚至反映出截然不同的规律.分别从时间和空间2个角度分析探讨了由于尺度选择不同可能带来的计算影响,分析结果将对流域沙量平衡计算的正确尺度选择具有重要意义.     

行星系设计条件研究

非均匀分布行星轮系在实际应用中具有广泛的领域，在此，列述了该类行星轮系的设计条件和计算步骤。     

空间角度自动计算软件系统的开发及应用

阐述空间角度自动计算软件系统的模块设计、功能及特点 ,为空间角度计算提供了新的方法和手段     

广义随机空间内结构可靠性优化设计

讨论了广义随机空间内随机参数服从正态分布的可靠性优化设计问题。在基本随机参数均值、方差和相关系数已知的情况下,避免了相关变量的独立变换以及求极限状态函数对基本变量的偏导数,应用可靠度指标计算的优化方法与有限元法相结合,并通过计算机程序给与实现,迅速准确地得到了可靠性优化设计信息。算例结果表明,本文提出的方法是一种有效、实用的方法。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...