液压基本回路组成

液压基本回路是用于实现液体压力、流量及方向等控制的典型回路,它由有关液压元件组成。现代液压传动系统虽然越来越复杂,但仍然是由一些基本回路组成的。因此,掌握基本回路的构成、特点及作用原理,是设计液压传动系统的基础。其主要包括压力控制回路、速度控制回路、方向控制回路、其他液压回路等。     

断路器跳位监视回路与防跳回路间寄生回路的危害分析及改进意见

目前国内断路器操作箱及机构箱分别由不同厂家设计,缺乏相互配合的参数标准。不同厂家生产的跳位监视回路和防跳回路之间可能会由于继电器的参数不匹配、设计不周全等原因产生寄生回路,影响断路器控制回路的正常功能。为了解决跳位监视回路及防跳回路产生寄生回路的问题,针对现阶段电力设备中存在的几类典型问题,通过回路分析法对断路器典型的控制回路进行了分析,结合跳位监视继电器及防跳继电器的动作特性,总结了常见的寄生回路缺陷及产生缺陷的原因,并从回路设计、生产标准、验收规范、改进方案等方面给出了解决方案和建议。     

CAD在液压回路设计中的应用

绘制液压回路图的软件与方法很多,CAD软件是其中的一种。为快速正确地绘制液压回路图,设计出合格的液压系统,熟练地应用计算机绘图CAD软件是十分必要的。本文以一液压基本回路图为例,深入描述了CAD软件在绘制液压回路图时的应用及以利用液压回路的特性,快速绘制液压回路的方法与技巧,大大提高了液压回路的设计效率。     

液压平衡回路动态特性建模与仿真

液压平衡回路是液压系统的基本控制回路,其广泛应用于工程机械领域,其中大部分平衡回路都是由平衡阀构成。平衡阀作为平衡回路中的关键元件,对平衡回路的稳定运行有着重要影响。通常情况下平衡阀的内部结构参数难以获取,因此基于平衡阀样本中的先导全开节流特性和溢流特性建立其数学模型,进而构建平衡回路的数学模型。采用MATLAB/Simulink对平衡回路进行仿真,结果表明,构建的数学模型可以反映平衡回路的动态特性以及使液压设计人员能够对平衡阀的选型进行评估。     

基于XML的智能变电站二次电回路建模与解析方法

为解决智能变电站二次电回路拓扑关系复杂,无法清晰建模表达和难于用软件解析的问题,提出一种基于XML（可扩展标记语言）的二次电回路建模与解析的方法。借鉴二次回路物理建模思路,通过XML格式定义电回路中常用元件、线缆和回路模型;通过不同的节点类型建立电回路的XML模型文件;利用建立的模型文件完成电回路信息的解析检索,生成可视化的二次电回路信息展示图。实际应用案例表明,该方法可提升智能变电站二次电回路信息的数字化表达、应用效率和准确性。     

泵试验回路阻力计算和应用北大核心

本文阐述泵试验回路的阻力计算方法。通过实际的计算实例列举了阻力计算在泵试验回路设计中的演绎应用,总结了试验回路阻力计算对回路实际流量测量的影响。     

工程机械液压换向回路的分析与比较

本文根据工程机械中换向回路的工作特点,提出了分析与比较换向回路的标准,并分析和比较了包括电液比例换向回路和插装阀换向回路在内的几种典型回路。     

断路器的监视与防跳回路研究

在断路器的控制回路中,位置监视和防跳回路相当重要,在控制回路中它们并不是单独作用的,而是相互联系的。当采用不同的防跳回路时,位置监视回路该如何接入才能起到监视整个合闸或分闸回路的作用,是值得技术人员关注的问题。现讨论使用不同防跳回路时监视回路的接法,在实际工作中具有一定的指导意义。     

电梯门回路检测功能分析及检验方法

介绍了电梯门回路检测功能的设置和检验要求,分析了门回路检测基本电路和电梯门回路检测时间节点,总结了电梯门回路检测功能检验中多轿门检验方法、与旁路功能的区别和电梯门回路故障复位策略要求等检验注意事项:供电梯检验人员参考。     

浅析工程机械液压调速回路

液压调速系统在工程机械中具有广泛的应用。分析了有级调速回路和节流调速回路,总结了它们的特点和功能,并就一种有级调速回路和旁油路节流调速回路进行了相关的理论计算和分析,说明了各类调速回路在工程机械中的应用。     

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...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

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.     

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...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.