高压直喷天然气发动机技术简介

缸内高压直喷(HPDI)天然气发动机是一款缸内喷入少量柴油、引燃直喷入缸内的天然气的1A型双燃料发动机。HPDI发动机可以保持同排量柴油机原有的性能;与传统点燃式天然气发动机相比,主要优势表现为动力强劲,燃气消耗低,可靠性高,排温低,响应快;与进气道喷射双燃料发动机相比,替代率高,经济优势明显,市场前景光明。     

中国第一台大功率缸内高压直喷压燃式天然气发动机上市

[本刊讯]由中国首家研发和生产缸内直喷天然气发动机的合资公司---潍柴动力西港新能源发动机有限公司推出的中国第一台大功率缸内高压直喷压燃式天然气发动机(简称"HPDI发动机")上市发布仪式2012年3月13日在北京钓鱼台举行。该     

天然气发动机的大功率革命

潍柴动力西港公司推出的高压直喷天然气发动机使用天然气为主要燃料,保证了发动机的动力、扭矩和效率,给传统的火花塞点燃式天然气发动机带来了一次革命性的科技创新。2012年3月13日,中国第一台大功率缸内高压直喷压燃式天然气发动机（HPDI发动机）正式上市。这一技术创新成果由潍柴动力西港新能源发动机有限公司推出,     

发动机冷试条件下的机油压力测试分析

在发动机检测中对机油压力的监测是保证发动机质量的重要一环。结合发动机冷测试原理,建立机油压力和机油温度关系曲线;提出机油温度补偿算法及发动机冷测试机油压力测试工艺参数制定方法,用以确定机油压力是否正确。引入质量管理中常用的控制图分析,从而判定机油压力在测试范围以内。运用AMESim仿真软件建立发动机机油压力测试模型,正确设置相关的参数,将仿真结果与实验数据做比较分析,验证了理论分析和数学模型的准确行,为实际生产提供参考。     

发动机传感器故障硬件在环仿真平台研究

针对发动机电控系统传统开发方法中存在的局限性,提出了一种传感器故障模拟系统的建立方法。首先,在LabVIEW、VeriStand开发环境下,为发动机电控系统功能测试开发了硬件在环仿真平台;其次,利用该平台对节气门位置、进气压力、冷却水温等传感器进行了信号故障模拟;最后,以节气门位置传感器信号故障为例,对所开发的故障容错功能包的有效性进行了验证,并将仿真结果与实车测试结果进行了对比。结果表明,利用该方法建立的系统符合测试要求,且具有使用方便、可靠性强、精度高等特点。     

发动机台架测试减振系统广义反馈控制研究

发动机台架试验是测试发动机性能的主要手段。在进行台架试验时,试验平台会产生很大的振动,对实验和设备都会产生影响。可调阻尼减振系统受可调阻尼器延滞性的影响在发动机进行瞬态试验时难于达到要求,而固定阻尼减振系统又缺乏纠正偏差能力。针对这一问题,提出一种广义反馈控制算法,并结合建立的台架测试振动模型进行仿真分析。根据仿真结果从时域和频率两个角度分析广义反馈控制对系统振动的影响。结果表明:广义反馈控制可以减小台架运行时系统的竖向振动,改善系统振动烈度。     

航空发动机加力状态控制系统设计与仿真

根据航空发动机加力状态控制计划,进行了加力状态控制系统的控制逻辑设计,并在该型发动机控制系统数字仿真平台上进行了喷口及加力燃烧室燃油流量控制器的仿真研究.仿真表明,设计得到的控制逻辑是合理、可行的,可以应用于航空发动机加力状态控制系统的设计.     

微小型涡喷发动机进气畸变压力场测试及数值仿真分析

基于某微小型涡喷发动机平台,开展发动机进气总压畸变压力场测试,将试验结果与经校验的数值仿真计算结果进行对照,确定了该试验方法的可行性.通过对进气道渐缩段的数值仿真,探讨了微小型涡喷发动机尺寸效应所带来的二次畸变的影响.结果 表明:该测量方法能够较好地评估小型涡喷发动机的抗畸变能力;进气渐缩段对进入压气机的畸变存在较大影...     

弹起式发动机罩的行人保护性能研究

行人保护是汽车主被动安全的重要内容。根据国标的行人保护试验规程和要求,建立了行人保护头型冲击器及弹起式发动机罩系统的有限元模型。对发动机罩面积进行划分,选取HIC值较大的位置作为碰撞点,通过仿真头部冲击器与发动机罩的碰撞过程,分析不同碰撞点的头部加速度时间历程,研究了弹起式发动机罩的行人保护性能。并搭建了用于发动机罩行人保护性能测试的跌落试验平台,实验验证了弹起式发动机罩的行人保护性能,证明了有限元模型的有效性。     

发动机控制器虚拟测试系统的开发与验证

传统的发动机控制器开发效率低、成本高,针对这些局限性提出了一种发动机控制器虚拟测试系统的搭建方法。该方法是将在ETAS INTECRIO环境下开发的发动机虚拟控制器与Matlab/Simulink环境下开发的车辆系统组成闭环系统,并实现在线故障注入功能。将虚拟测试系统的仿真结果与实车测试结果及硬件在环测试结果进行对比验证,结果表明该虚拟测试系统符合控制器初期开发测试要求,且使用方便、成本较低,可以显著提高发动机控制器的开发效率。     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.