基于QCS003B的节流调速性能的实验研究

采用QCS003B型液压实验台对节流调速回路速度和负载数据进行采样,并利用这些实验数据对进油路节流调速回路、回油路节流调速回路及旁油路节流调速回路的速度负载特性进行了实验性研究。研究表明节流调速回路的实验结果与理论分析基本吻合。     

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。     

基于AMESim的液压回油节流调速回路建模与仿真

介绍了节流调速回路的工作原理,并对其特性进行理论分析,利用AMESim仿真软件对回油节流调速回路进行建模和仿真,获得回油节流调速回路的基本特性,从而为回油节流调速回路的设计与优化提供参考。     

节流调速回路效率特性探讨

节流调速回路是液压系统中应用最广的回路之一。进口与出口节流调速回路特性相同。在定量泵系统中,由节流阀与溢流阀配合工作实现调速的原理,决定了节流调速过程中伴随着较大的功率损失。各种使用节流调速的系统都采取不同的速度换接措施并合理地匹配参数,以求在较大的调速范围内获得尽可能高的工作效率。因此,研究节流调速回路的特性及影响效率的因素,从而寻找提高效率的有效措施,是必要的。各类有关参考书都对节流调速回路的特性进行了专题分析。近年出版的几本参考书又在传统分析的基础上导出进口节流调速回路效率不大于0.385的结论。     

固体颗粒污染物对节流调速回路速度启动特性的影响

通过试验分析固体颗粒污染物对液压节流调速回路启动时间的影响,在不同的污染条件下比较节流调速回路的启动时间,实验的结果有利于液压节流调速系统的设计和实施污染控制措施.     

节流调速回路的效率问题

对三种节流调速回路的效率进行了简要分析,列出了实验曲线,证明进、出口节流调速回路的效率可达0.7～0.8;相同条件下两者的效率相等;负载相同时调定压力相等;薄壁式与三角槽式节流阀调速回路的效率无明显差异。     

液压节流调速回路速度启动特性的试验研究

通过试验和对速度的测量, 分析了采用节流阀和调速阀的进口节流、出口节流、旁路节流回路的启动特性, 并对这些回路进行了比较, 为设计节流调速回路提供了依据     

用节流阀和调速阀的进油节流调速回路速度-负载特性研究

通过实验,对分别采用节流阀和调速阀的进油节流调速回路的速度负载特性进行了研究,并做出了速度负载特性曲线,得出了采用调速阀的进油节流调速回路的适用条件,对正确对待和使用这两种调速方式提供了参考。     

负荷相关减压阀回油节流调速及其应用研究

文章探讨一种新型负荷相关减压阀及其在液压回油节流调速回路中的应用,介绍应用该减压阀的调速回路与普通的回油节流调速回路在试验台和机床上的使用比较。     

一种大型液压升降机构的节流调速及节能回路设计与研究

在对传统大型升降机构的液压节流回路进行分析的基础上,研究开发出一种大型液压升降机构的节流调速及节能回路,分别对该回路中节流调速回路及节能回路的特性进行分析,最终确定复合液压缸及调速阀的作用,可实现在负载变化的条件下,升降机构匀速下降,且其下降速度取决于调速阀阀口的过流面积,从而降低了升降机构对机构整体框架的冲击;通过复合液压缸与蓄能器的综合作用,实现了液压系统的节能。对液压系统进行实验验证,证明该液压系统下降速度平稳,符合液压升降机构工况实际应用需要。     

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.