一种基于阶跃响应的理想频率信号源及频域分析的研究

为解决以阶跃信号为激励的阶跃时域响应法难以掌握分析对象本质特性的问题,深入分析了阶跃信号的频谱特性,指明阶跃实质上是一种频率响应法的理想频率信号激励源,首次提出了阶跃响应不仅可用于时域分析,而且能充当回路频域分析的数据源,并设计采用了点频滤波器将阶跃响应用于回路频域分析.仿真试验和实际应用结果验证了文中提出的基于阶跃响应频域分析方法的正确性和有效性.     

发动机冷却风扇对车内振动噪声影响分析

针对某车型开发过程中的问题进行了详细分析,研究了风扇振动导致的车内噪声的问题。通过模拟分析对风扇加载,得到车内不同位置的响应,模拟结果与实际测试结果吻合。在无法更改激励源激振频率的情况下,研究了使用板贡献量的方法找到车内贡献最大的结构,通过改善结构降低了车内的响应。     

非燃烧激励对缸盖燃烧激励振动影响模拟分析

模拟了活塞换向撞击、侧压力、曲轴主轴颈负荷单独作用及各激励和燃烧激励共同作用时引起的缸盖表面振动信号,并对各激励振动响应信号的时频特点进行了分析．结果表明,各激励引起的缸盖表面振动位移主要反映了2kHz以下的低频振动,振动速度和加速度能同时反映系统的低频及高频振动,在时域和频域上各激励振动响应存在耦合．但侧压力及曲轴主...     

管道渗漏区探地雷达响应特征分析

探地雷达在供水管道渗漏区探测方面具有广阔的应用前景。为增强渗漏区探地雷达响应特征的认识，提高渗漏区定位精度，基于时域有限差分法，模拟金属管道底部渗漏的探地雷达响应特征，并提取“三瞬”地震属性进行分析。结果表明，渗漏区上边界信号易识别，内部信号存在多次反射和震荡现象；渗漏区瞬时振幅属性与原始剖面反映效果相似，瞬时相位属性同相轴错断明显，瞬时频率属性明显衰减；瞬时相位属性和瞬时频率属性对渗漏区的存在及微弱信号反映效果较好，故渗漏区瞬时属性分析时优选瞬时相位属性和瞬时频率属性。结果可为探地雷达管道渗漏区探测图像解译和实际工程应用提供参考。     

基于盲源分离的柴油机激励源振动响应分离方法研究

提出了1种基于盲提取、消减方法的盲源分离幅值不确定的解决方法,利用消减前后的混合信号得到已提取的源信号在观测点处的响应.理论分析可知这样得到的结果就是激励源在观测点处的响应,不存在幅值模糊性.数值仿真的结果表明了这种方法能够有效地实现源信号响应的分离.最后对柴油机机体振动信号进行了分析,提取出柴油机活塞-缸套撞击信号,进而得到其在传感器测点位置的振动响应,实现了柴油机振动激励源响应的分离.     

弹性支撑下柴油机的冲击响应分析

针对某型柴油发电机组进行了在正常运转弹性支撑下的冲击试验,测试了柴油机加速度响应.分析结果表明:实测加速度响应是柴油机自身运转、外来冲击和测量噪声的综合作用结果.通过高通滤波滤除加速度信号的超低频干扰后,二次积分得到了位移响应信号.利用小波分析方法分离出了冲击响应,该冲击响应由隔振器的低频振动和限位器引起的高频振动两部分构成.计算了机脚加速度信号的冲击响应谱,利用该响应谱得到了等效的组合半正弦加速度信号,为弹性支撑柴油机的抗冲击仿真计算提供了冲击输入环境.     

车用发动机道路行驶工况的模拟实验研究

利用计算机采集发动机信号,实时地计算出发动机的运行参数,控制信号由计算机通过接口电路输出到测功机,并可在计算机中编程进行控制测功机的励磁电流的变化,这样就可以实时地满足发动机各种变工况的运行需要,从而实现车用发动机道路行驶工况的模拟     

基于小波技术的柴油机振动信号特征参数的研究

在1110柴油机上模拟了气门漏气、气门间隙异常、供油时刻异常及喷油压力异常4种常见故障,并测得了几种故障下缸盖振动信号和缸内压力信号.对振动信号常用的几种分析方法进行对比研究,并选定小波分析法对振动信号进行时频分析,提取振动信号的特征参数.试验发现:气门漏气时整个缸盖振动信号高频带能量增加、低频带能量降低;气门间隙增大时,高频振动响应信号能量增强;供油提前角增大时,缸内燃烧始点提前,缸盖振动信号低频带信号能量增加;喷油压力增大时,缸盖振动信号中低频带信号所占能量增加.     

基于FPGA的混合信号控制结构的设计

提出了一种基于现场可编程门阵列(FPGA)的混合信号控制结构.该控制结构仅包含了一个FPGA控制器、一个DAC转换器以及一个比较器.这种混合信号的控制结构具有即时响应的优点,其动态特性非常接近模拟控制方案.更重要的是,在该控制结构中所用器件都适合功率集成.这种混合控制结构的优良性能为其在更多工业控制系统中的应用提供了可...     

炉膛辐射能信号的提取机理及其应用研究

火焰图像可以快速地反映出电站燃煤锅炉入炉燃料的质和量的变化,通过对火焰图像信息的处理,分析了辐射能信号提取机理并对其进行了量化。在1台300 MW电站锅炉上的实际运行表明,炉膛辐射能信号能够快速响应燃烧率的变化;将其作为燃烧放热的主令信号,建立协调控制模型并参与机组负荷控制是可行的。图7表1参8。     

便携式发动机工况信号模拟器的设计与开发

开发了一种简单、便携的发动机工况信号模拟器。硬件上，通过内置键盘／LCD界面为用户提供了灵活的发动机传感器信号参数设定模式；软件上，通过MAP图模型为用户提供丁简单的ECU硬件在环调试手段，解决了ECU调试中传感器信号灵活组合的问题。试验结果表明：所开发的发动机工况信号模拟器能够灵活地输出发动机传感器的组合信号，对发动机ECU软件逻辑调试和故障测试起到了良好的辅助作用。     

汽轮发电机组扭振模拟机的轴系设计

介绍了汽轮发电机组轴系扭振模拟系统的设计原则,利用雷卡迪传递矩阵分析计算了汽轮发电机组轴系扭振的固有特性。依据设计原则,利用模态刚度矩阵、模态质量矩阵和模态频率相似进行了扭振模拟机轴系的设计,扭振模拟机轴系前三阶固有特性与实际机组轴系扭振动特性基本一致。试验表明,扭振模拟机达到了设计目的,同时也证明了轴系分析方法和设计方法的正确性。     

Effect of winds in a mountain pass on turbine performance

Mountain passes are potentially advantageous sites for the deployment of wind turbines because of road links and electrical transmission infrastructure. However, relatively little is known about wind characteristics and turbine response in these environments. Using hub height wind data from a mountain pass in Switzerland, this paper discusses the causes of the observed pass winds and how a generic wind turbine might perform in those conditions. During 3 months of winter measurements, the winds in the pass showed signatures of forcing by regional pressure gradients rather than local cooling or heating. Turbulence intensity was often less than 10%, and the magnitude of the wind shear power law exponent was less than 0.1. To understand the impact of pass winds on a wind turbine, we simulated a Wind Partnership for Advanced Component Technologies 1.5 MW wind turbine using the Fatigue, Aerodynamics, Structures, and Turbulence (FAST) aeroelastic simulator , forced by artificial wind fields of varying turbulence intensity and shear generated by the turbulence simulator TurbSim. We used the turbine simulation data to train a regression model that is used to predict the turbine response to the pass wind time series. Results showed that depending on long‐term wind characteristics, wind turbines in the pass may perform differently than predicted using a power curve derived from test measurements at another location. This method of generating site‐specific energy capture predictions could be combined with long‐term wind resource data and specific turbine models to better predict the energy production and turbine loads at this, or any other site. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental investigation of the steady-state efficiency of fuel cell stack under strengthened road vibrating condition

The steady-state efficiency of the fuel cell stack is experimentally investigated in terms of steady-state hydrogen utilization, actual efficiency and maximum efficiency point through a 162 h strengthened vibration test in this paper, in order to analyse the steady-state performance of the fuel cell stack under long-term vibrating condition on strengthened roads. The load spectra applied in the test are simulated by the acceleration signals of the fuel cell stack, which are previously measured in a vehicle vibration test. The load signals of the vehicle vibration test are iterated through a road simulator from vehicle acceleration signals which are originally sampled in the strengthened road of the ground prove. The test results show that the steady-state hydrogen utilization of the stack decreases by 30.7% during the test. The maximum drop of steady-state actual efficiency is 21.0%. Additionally, the maximum efficiency point of the stack declines by 5.4%, while the corresponding current experiences an increment of 47.2 A. From the results it can be concluded that the strengthened road vibration exerts a significant influence on the steady-state performance of the fuel cell stack, which cannot and should not be ignored during the research.     

Modelling of NOx emission factors from heavy and light-duty vehicles equipped with advanced aftertreatment systems

NO_x emission standards are becoming stringiest over the world especially for heavy-duty vehicles. To comply with current and future regulations some vehicle manufacturers are adopting exhaust aftertreatment systems known as Selective Catalytic Reduction (SCR). The catalysts are based on Vanadium (Va) and the reductant agent based on ammonia. However, Va is listed on the California Proposition 65 List as potentially causing cancer and alternatives are being studied. This paper presents a model based on neural networks that integrated with a road vehicle simulator allows to estimate NO_x emission factors for different powertrain configurations, along different driving conditions, and covering commercial, zeolite and mordenite alternatives as the base monolith for SCR. The research included the experimental study of copper based and iron based zeolites (ZSM5 and Cuban natural mordenite). The response of NO_x conversion efficiency was monitored in a laboratory for varying space velocity, oxygen, sulfur, water, NO_x and SO₂ emulating the conditions of a Diesel engine exhaust along a trip. The experimental data was used for training neural networks and obtaining a mathematical correlation between the outputs and inputs of the SCR system. The developed correlation was integrated with ADVISOR road vehicle simulator to obtain NO_x emission factors and to test each SCR system installed on light-duty and heavy-duty vehicles for standardized driving cycles and real measured driving cycles. Despite having lower NO_x conversion efficiencies than the CATCO in the ETC/ESC and NEDC cycles, FeZSM5 maintain the Euro regulation level. Therefore FeZSM5 can be a possible candidate as far as pollutants regulation is considered.     

Experimental investigation of gas-tightness and electrical insulation of fuel cell stack under strengthened road vibrating conditions

Gas-tightness and electrical insulation are two important evaluation indexes of fuel cell vehicle safety. In this paper, the variation of gas-tightness and electrical insulation of fuel cell stack under long-term vibrating conditions are experimentally investigated through a 150 h strengthened vibration test. The load spectra applied in the test are simulated by the acceleration signals of the fuel cell stack, which are previously measured in a vehicle vibration test. The load signals of the vehicle vibration test are iterated through a road simulator from vehicle acceleration signals which are originally sampled in the strengthened road of the ground prove. The test results show that the hydrogen leak rate of the stack increases 1.5 times during the test. Additionally, the insulation resistance of the stack experiences a rapid decline at first, and then a steady linear decrease to 17.55% of the original value. It is observed that the decrease rate at the first stage is 25 times higher than the one at the second stage.     

基于运行工况的纯电动车与汽油车能耗排放比较分析

基于济南市城市道路运行工况,对比分析了纯电动汽车和传统燃油汽车的能耗及排？放。根据纯电动汽车及传统燃油汽车的实车道路~,riL数据,利用主成分分析、聚类分析等方法构建了济南市城市道路工况。基于该工况,对比分析了上述两种车辆的能耗和排放,分析得出在该道路工况下纯电动汽车的能耗约为传统燃油汽车的1／2,排放方面也明显低于后者。     

Consumption modeling based on Markov chains and Bayesian networks for a demand side management design of isolated microgrids

This paper proposes a novel simulator of energy consumption patterns that allows designing demand side management (DSM) strategies without economic incentives. The simulator emulates consumers' patterns with and without installed DSM interfaces, based on both actual consumption measurements and surveys applied to the inhabitants of an existing isolated microgrid (Huatacondo, Chile) that has a particular DSM strategy without economic incentives. The simulator uses Markov chains to generate data characterizing consumption patterns without DSM and Bayesian networks for cases in which the users respond to the DSM strategy. Data obtained from the simulator are used to derive a response model of the consumers to the DSM interface, which can be included for the energy management system design. Results show that the implemented strategy can be effective and can generate savings up to 4.45% in diesel consumption for an ideal case where all the dwellings have the interface installed. Copyright © 2016 John Wiley & Sons, Ltd.     

Impact of real world driving pattern and all-electric range on battery sizing and cost of plug-in hybrid electric two-wheeler

This study addresses the impact of an actual drive pattern on the sizing and cost of a battery pack for a plug-in hybrid electric two-wheeler. To estimate the daily average travel distance in fixing the all-electric range of two wheelers, a study conducted in Coimbatore city is presented. A MATLAB simulation model developed for estimating the energy and power requirements in an all-electric strategy using an Indian driving cycle (IDC) and a real-world driving pattern are discussed. The simulation results reveal the impact of the real-world driving pattern on energy consumption and also the influence of all-electric range in sizing the battery pack. To validate the results, a plug-in hybrid electric two-wheeler developed by modifying a standard two-wheeler has been tested on the road with the help of the IDC simulator kit. An annual battery cost comparison shows that nickel-metal-hydride batteries are more economical and suitable for in plug-in hybrid electric two-wheelers.     

电子节气门滑膜变结构控制硬件在环仿真的试验研究

运用滑膜变结构控制原理设计了电子节气门的滑膜变结构控制器。利用电子节气门、发动机信号发生器、标定软件和油门踏板搭建了电子节气门硬件在环仿真平台,对滑膜变结构控制器控制效果进行了测试。结果表明：平台能够产生各种发动机传感器信号,ECU与标定软件、信号发生器通信畅通,可以静态的模拟发动机工况,满足硬件在环测试的功能要求。采用滑膜变结构控制,能很好地克服系统中的非线性及扰动,具有迅速的瞬态特性和良好的稳态特性。