紊流流体管路分段集中参数键图模型研究

对传统管路分段集中参数模型进行修正,通过引进动摩擦液阻,提出了适用于紊流管路的分段集中参数键图模型.仿真曲线和试验曲线吻合较好,表明所提出的管路模型具有足够的精度.该模型结构简单,计算参数少,适合于复杂管路系统的建模分析.     

基于FLUENT的直管气体输送参数的研究

对气体通过水平直管进行研究,计算管道中的压力损失、速度等参数,采用分段思想对长直水平管进行分段计算压力损失,得到较为精确、实用的压力损失计算方法。利用FLUENT软件进行模拟仿真计算,比较分段计算的结果和软件仿真计算结果的差异,并分析产生误差的原因,为以后气体输送的管道设计提供理论依据。     

细长管道对汽车ABS制动压力响应滞后影响研究

首先介绍了反比例压力阀控制的汽车ABS系统,建立了盘式制动器数学模型,利用液压系统动态仿真软件DSHW建立了具有细长制动管道的汽车ABS系统模型,同时建立汽车ABS实验系统。探讨了细长管道对制动压力响应,结果表明:细长制动管道对制动压力响应存在滞后影响,管道越长,滞后时间越长;在负阶跃响应时比较明显,在正阶跃时滞后比较小。     

大型矿用液压挖掘机行走系统建模及仿真研究

大型液压挖掘机履带行驶系统的传统计算方法精度低、仿真计算的难度大,针对这种状况,提出了一种改进的仿真方法。该方法通过数据表将动力学软件仿真得到的力学参数导入到系统仿真软件SimulationX中进行液压系统仿真计算,对履带前进和后退两种基本工况下的动力学机构仿真结果和液压系统仿真结果进行分析。通过对仿真结果与理论计算结果的比较,证明该方法得到了较好的履带行走系统整体仿真计算精度和较快的仿真计算速度,为大型液压挖掘机履带行走系统的精确设计提供了一种较为实用的方法。     

紊流流体管路分段集中参数键图模型研究

对传统管路分段集中参数模型进行修正,通过引进动摩擦液阻,提出了适用于紊流管路的分段集中参数键图模型。仿真曲线和试验曲线吻合较好,表明所提出的管路模型具有足够的精度。该模型结构简单,计算参数少,适合于复杂管路系统的建模分析。     

飞机液压系统伺服舵机热力学分析与计算

为减少飞机液压系统故障,从温度控制层面对飞机液压伺服舵机进行热力学分析。将液压伺服舵机的物理模型简化为伺服阀控制作动筒的形式,建立液压伺服舵机热力学模型。根据热力学第一定律,采用集中参数法建立热力学方程。基于MATLAB平台,采用龙格-库塔法对舵机热力学模型进行编程仿真计算,得出舵机各节点温度分布曲线。将仿真结果与实验数据进行了对比,对比结果验证了飞机液压伺服舵机热力学模型的正确性,该模型可应用于飞机液压系统动态温度计算。     

考虑软管粘弹性的液压伺服系统建模与仿真研究

利用管道集中参数模型和软管粘弹性模型，给出了一种对采用软管的液压伺服系统进行数学建模的方法，利用这种方法通过仿真分析了软管对系统的影响，仿真结果同已有的结论符合，验证了这种建模方法的正确性。     

高压断路器高速工作缸缓冲过程研究

针对高压断路器工作缸在高速重载工况下内部会产生剧烈液压冲击现象的问题,以某型号液压操动机构的台阶型活塞工作缸为研究对象,对高压断路器工作缸分段缓冲节流过程进行了集中参数建模,对高压断路器工作缸缓冲过程进行了CFD仿真分析,根据仿真结果提出了两种体现不同的液压油节流渐变过程的优化方案,即通过雷诺数的变化来模拟工作缸缓冲过程和通过工作缸活塞台阶进入距离与紊流层流的变化关系来模拟工作缸缓冲过程。研究结果表明:相较于普通缓冲节流过程模型,优化后的模型能更加准确地针对工作缸的缓冲过程进行模拟仿真,具有更高的计算精度与工程实用价值。     

工程应用液压伺服系统仿真

从工程应用的角度出发介绍液压伺服系统仿真.从实用角度出发液压系统仿真共分两种,第一,通过理论计算传递函数建模后,经过控制方面的软件进行液压系统仿真;第二,通过专业的液压系统仿真软件,用绘制原理图即图形建模的形式进行系统建模,并对元件输入参数进行系统输出的仿真.在分析两种仿真方法过程中进行举例说明.     

新的液压管路分段集中参数键图模型及其试验研究

在传统的管路分段集中参数模型的基础上,引进动摩擦液阻,提出了新的管路分段集中参数键图模型.经与研究管路动态的特征线法和分布参数键图法的对比分析,确定了动摩擦液阻的表达式.试验验证了所提出模型的正确性.该模型物理意义明显、直观,计算参数少,仿真能力强,因而更便于工程应用.     

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.     

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。     

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....     

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.