液压系统监测诊断中的传感器优化配置技术

对液压系统进行在线监测诊断,需要获得尽可能完备的状态信息,但也带来了传感器布设难度和监测成本增加等问题。该文提出了一种基于多目标优化的传感器配置方法,采用故障检测率、状态分辨率、故障虚警率等约束条件,将故障隔离率和综合成本作为优化目标,构建了传感器优化配置模型。实践证明,通过优化后的传感器配置方案在保证监测诊断准确性的基础上,能够有效降低成本,提高布设效率。     

电能质量监管系统网络化拓扑结构的设计

研究一种有着网络化、信息化、社会化和智能化的电能质量监测与管理分析系统。此系统集成了监测、通信、管理和控制等功能,可有效进行电能质量的实时监测、上位机与下位机的通信以及对多谐波源的谐波责任监管等。首先在分析国内外文献基础上,通过有效合理的电能质量监测终端优化布局,建立了一种基于无线网络的网络化电能质量监测拓扑,该拓扑结构能够及时有效地进行电能质量监测信息与智能决策的对接,从而实现电力用户和管理部门之间的信息共享。     

基于GPRS和GPS的三相电能质量监测仪

针对目前电力系统配网中谐波污染日益严重的情况,提出了一种基于GPRS无线通信和GPS同步采样的低成本电能质量监测装置.该装置通过采用GPRS无线通讯技术,极大地节省了通讯设施的建设费用,同时凌阳处理器的使用也有效地降低了装置的成本.GPS对时技术的引入既提高了系统同步采样精度,又为故障识别、谐波源源定位及谐波状态估计提供了重要的前提条件.     

并网光伏电站电能质量实时监测系统

并网光伏电站的电能质量问题已经成为制约光伏发电技术发展的关键因素之一,进行实时电能质量监测有助于光伏发电技术的改进和提高,对于保障电网安全稳定运行具有重大意义.文中开发了一种基于虚拟仪器的并网光伏电站电能质量实时监测系统,该系统实现了对并网光伏电站电能质量三项稳态指标的监测,利用LabSQL模块和数据库技术实现数据存储以及基于C/S模式、B/S模式和Remote Panels技术的信息远程发布方案,使监控中心可通过Internet直接查看即时和历史电能质量数据,实现信息共享.同时利用7.68 kWp光伏电站对文中开发的系统进行验证,试验结果表明该系统能满足实时、准确、长期、连续的实际测量需要.     

主动配电网储能优化规划

大量分布式电源的接入使得主动配电网成为现有配电网的发展趋势及方向,可再生能源发电的间歇性将会提高配电网的风险,解决这些问题最有效的方法就是配置适当的储能装置,合理地优化配置储能装置不仅能提升主动配电网对分布式能源的消纳能力还能提高主动配电网运行的稳定性。主动配电网储能长期优化规划以短期优化为基础,短期优化考虑了储能系统的削峰填谷及调节馈线节点电压水平的能力从而决定储能的额定功率,长期优化规划模型以主动配电网经济运行成本最小为目标函数考虑储能投资成本以及主动配电网的运行成本及可靠性成本,通过禁忌搜索-粒子群混合算法求解得到电池储能装置的最优位置、容量及额定功率,算例验证了所提模型及其求解方法的可行性。     

基于准同步采样技术的配电网电能质量在线监测装置

研制了一种新型电能质量在线监测装置,采用数字信号处理器和大容量闪烁存储器对配电网频率、基波、谐波等运行参数进行实时分析和不间断存储.其数据采集环节运用准同步技术,通过对工频周期实时估算和采样序列指针周期性复位的方式,不仅实现了频率变化输入信号的相位锁定和整周期采样.还能显著提高输出频谱的响应速度.此外,监测装置和PC系统的数据通信与监测数据二次分析软件相配合还突破了电能质量分析的单点模式,并实现了综合监测报告的自动生成.实验室样机的测试结果与参考仪表数据相一致,表明该装置在实时谐波分析与在线电能质量监控应用中具有良好表现.     

基于GPS同步信号源的电能相量测量系统研究

以大规模配电网的电能相量测量为研究对象,采用全球定位系统(GPS)接收器开发了一种适合于同步信号源的电量连续监测技术。与专业的相量测量装置不同,所提出的测量方法仅需使用通用型数据采集卡(DAQ)和处理软件即可实现对电能相量的测量,利用高精度GPS接收器实现不同远程装置之间的数据同步,结合长度固定窗口和长度可调窗口2种测量方式对同步相量的绝对相位进行评估。通过对模拟信号和实际信号的测试分析,结果表明,DAQ可以达到与专业硬件相同的同步精度数量级,且所提出的2种测量方式的精度均满足配电网系统状态估计、控制和继电保护的要求。     

可扩展的在线电能质量监测系统

为了实时监测不同规模大小的电力系统上的电能质量,设计了一种可扩展的在线电能质量监测系统.该系统基于模块化的设计思想,将传统的电能监测系统划分为电流检测模块、电压检测模块和主控制模块,实际应用中可以根据所要监测的电力系统的规模大小灵活配置多个电流电压检测模块来同时监测不同通道上电能质量情况,并能够通过与远程主机实现通信,实现历史数据维护和数据分析,很好地满足了现代电能监测系统网络化,实时性和灵活性的要求.     

基于谐波限值的分布式电源准入功率研究

针对分布式电源接入配电网后会对电网电能质量产生不利影响的问题,对分布式电源的接入容量及位置进行了研究。在以配电电能质量符合国家标准的前提下,采用一种结合人工蜂群算法的分布式电源准入功率最大化配置方法对分布式电源准入功率进行了计算。针对多种分布式电源接入配电网的情况,首先分析了不同接入位置和不同容量的分布式电源对电网的影响;然后考虑了分布式电源对配电网电压偏差和谐波的影响;最后利用算例对优化配置方法的可行性进行了测试,确定了分布式电源接入配电网的优化配置方案。研究结果表明,该优化方案能够达到优化目标,满足电压调整和谐波畸变限制的约束条件,最大化地提高分布式电源准入功率,同时为分布式电源最佳接入点提供参考。     

考虑风电出力不确定性的储能容量机会约束规划配置

储能系统对风能等可再生能源实现可调度运行有着十分重要的作用.针对风电出力的不确定性问题,提出了一种基于机会约束规划的电池储能系统(BESS)容量配置方法.考虑风电利用率和储能装置荷电状态(SOC)约束,以储能成本最低为目标,采用模拟技术和遗传算法相结合的方法求解,得到了风电输出波动不超过某一区间的置信度与储能最佳配置成本间的关系.此外,在储能系统的控制策略中引入了放电惩罚因子,修正了储能装置的充放电功率,从而达到了延长使用寿命的效果.研究结果表明,BESS容量配置方法在电能质量和经济性间取得了适度的折中.     

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.