A Multi-mode Electronic Load Sensing Control Scheme with Power Limitation and Pressure Cut-off for Mobile Machinery

In mobile machinery,hydro-mechanical pumps are increasingly replaced by electronically controlled pumps to improve the automation level,but diversified control functions(e.g.,power limitation and pressure cut-off)are integrated into the electronic controller only from the pump level,leading to the potential instability of the overall system.To solve this problem,a multi-mode electrohydraulic load sensing(MELS)control scheme is proposed especially considering the switching stability from the system level,which includes four working modes of flow control,load sensing,power limitation,and pressure control.Depending on the actual working requirements,the switching rules for the different modes and the switching direction(i.e.,the modes can be switched bilaterally or unilaterally)are defined.The priority of different modes is also defined,from high to low:pressure control,power limitation,load sensing,and flow control.When multiple switching rules are satisfied at the same time,the system switches to the control mode with the highest priority.In addition,the switching stability between flow control and pressure control modes is analyzed,and the controller parameters that guarantee the switching stability are obtained.A comparative study is carried out based on a test rig with a 2-ton hydraulic excavator.The results show that the MELS controller can achieve the control functions of proper flow supplement,power limitation,and pressure cut-off,which has good stability performance when switching between different control modes.This research proposes the MELS control method that realizes the stability of multi-mode switching of the hydraulic system of mobile machinery under different working conditions.

稀燃条件下甲烷-空气预混射流的着火特性

基于可控热氛围燃烧试验系统,探究射流当量比、射流速率和协流速率对甲烷-空气预混射流着火特性的影响。根据试验规律对天然气发动机稀薄燃烧的控制策略提出优化建议,以减少失火现象的发生。结果表明:随着协流温度的升高,甲烷-空气预混射流的稀燃极限降低而富燃极限升高,符合大多数碳氢燃料预混合气的着火界限分布规律。不同的射流速率和协流速率下均存在临界当量比,当低于临界当量比时,着火温度随射流当量比的升高而显著降低,当高于临界当量比时,着火温度趋于稳定。在较低的射流当量比工况(0.20~0.62)下,提高射流速率可以降低着火温度从而优化着火性能。

Fault prediction method for nuclear power machinery based on Bayesian PPCA recurrent neural network model

Early fault warning for nuclear power machinery is conducive to timely troubleshooting and reductions in safety risks and unnecessary costs. This paper presents a novel intelligent fault prediction method, integrated probabilistic principal component analysis(PPCA), multi-resolution wavelet analysis, Bayesian inference, and RNN model for nuclear power machinery that consider data uncertainty and chaotic time series. After denoising the source data, the Bayesian PPCA method is employed for dimensional reduction to obtain a refined data group. A recurrent neural network(RNN) prediction model is constructed, and a Bayesian statistical inference approach is developed to quantitatively assess the prediction reliability of the model. By modeling and analyzing the data collected on the steam turbine and components of a nuclear power plant, the results of the goodness of fit, mean square error distribution, and Bayesian confidence indicate that the proposed RNN model can implement early warning in the fault creep period. The accuracy and reliability of the proposed model are quantitatively verified.

The Application of Combination Forecasting Model in Forecasting the Total Power of Agricultural Machinery in Heilongjiang Province

Agricultural machinery total power is an important index to reflect and evaluate the level of agricultural mechanization. Firstly,we respectively made use of exponential model,grey forecasting and BP neural network to construct models depending on historical data of agricultural machinery total power of Heilongjiang Province; secondly,we constructed the combined forecasting models that respectively based on divergence coefficient method,quadratic programming and weight distribution of Shapley value. Fitting results showed that the various combination forecasting model is superior to the single models. Finally,we applied the combination forecasting model which based on the weight distribution method of Shapley value to forecast Heilongjiang agricultural machinery total power,and it would provide some reference to the development and program for power of agriculture machinery.

Environmental life cycle assessment of Indian coal-fired power plants

Coal is the backbone of the Indian power sector. The coal-fired power plants remain the largest emitters of carbon dioxide, sulfur dioxide and substantial amounts of nitrogen oxides, which are associated with climate and health impacts. Various CO2 mitigation technologies （carbon capture and storage--CCS） and SO2/NOx mitigation technologies （flue gas desulfurization and selective catalytic reduction） have been employed to reduce the environmental impacts of the coal-fired power plants. Therefore, it is imperative to understand the feasibility of various mitigation technologies employed. This paper attempts to perform environmental life cycle assessment （LCA） of Indian coal-fired power plant with and without CO2, SO2 and NOx mitigation controls. The study develops new normalization factors for India in various damage categories, using the Indian emissions and energy consumption data, coupled with the emissions and particulate emission to come up with a final environmental impact of coal-fired electricity. The results show a large degree of dependence on the perspective of assessment used. The impact of sensitivities of individual substances and the effect of plant efficiency on the final LCA results is also studied.

Multi-train modeling and simulation integrated with traction power supply solver using simplified Newton–Raphson method

Multi-train modeling and simulation plays a vital role in railway electrification during operation and planning phase. Study of peak power demand and energy consumed by each traction substation needs to be deter- mined to verify that electrical energy flowing in its railway power feeding system is appropriate or not. Gauss-Seidel, conventional Newton-Raphson, and current injection methods are well-known and widely accepted as a tool for electrical power network solver in DC railway power supply study. In this paper, a simplified Newton-Raphson method has been proposed. The proposed method employs a set of current-balance equations at each electrical node instead of the conventional power-balance equation used in the conventional Newton-Raphson method. This concept can remarkably reduce execution time and computing complexity for multi-train simulation. To evaluate its use, Sukhumvit line of Bangkok transit system （BTS） of Thai- land with 21.6-km line length and 22 passenger stopping stations is set as a test system. The multi-train simulation integrated with the proposed power network solver is developed to simulate 1-h operation service of selected 5-min headway. From the obtained results, the proposed method is more efficient with approximately 18 % faster than the conventional Newton-Raphson method and just over 6 % faster than the current injection method.

Key Problems of Cold Power Spinning of Ti-15-3 Alloy

The key problems of cold power spinning of Ti-15-3 alloy are studied. Reasonable billet preparation methods are presented to improve crystal structure and avoid crack of billet. Influences of original wall thickness, reduction rate and feed rate on expanding in diameter are analyzed and some methods to prevent expanding in diameter are given.

Application of Space-time Conservation Element and Solution Element Method in Intake and Exhaust Flows of High Power Density Diesel Engine

A one-dimensional pipe flow model of single-cylinder diesel engine is established to investigate the intake and exhaust flow characteristics of diesel engine in the condition of high power density(HPD).A space-lime conservation element and solution element(CE/SE)method is used to derive the discrete equations of the partial differential equation for the intake and exhaust systems.The performance parameters of diesel engine with speed of 2100 r/min are simulated.The simulated results are in accordance with the experimental data.The effect of increased power density on charging coefficient is analyzed using a validated model.The results show that the charging coefficient is slowly improved with the increase in intake pressure,and is obviously reduced with the increase in engine speed.

Investigation on some key problems of large power AC-DC-AC converter

China is an important country in iron and steel industry.Power electronics converters are widely used.For the cold rolling mills of high speed,AC-DC-AC converters should be used.In the paper,the design and the control system of the large power three-level AC - DC - AC converter with IGCTs is investigated,and a back-to-back large power three-level AC - DC - AC converter with IGCTs has been got. With a series experiments,the performance of the converter is examined.The experiment result indicates the converter reaches the design requirement and it shows excellent performance.The converter system has been put into use safely.It is estimated that the AC - DC - AC converter system will be used in the drive systems for rolling mills in the near future.

South Aeronautic Power Machinery Company and South Brand Motorcycles

A backbone enterprise under the ChinaAviation Industry Corporation,theSouth Aeronautic Power MachineryCompany is well known for its South brandmotorcycles.The SAPMC is the coreenterprise of the China South Aviation PowerMachinery Group,which is among China’sfirst 56 large-scale enterprise groups approvedby the State Council.In 1994,the

Review on Development of Chinese Power Industry in 2002-2006

The 16th National Congress of the Communist Party of China was held inNovember 2002. In the five years since then, great changes took place in Chinesepower industry. Power institutional reform was deepened; the construction ofboth power sources and power grids was speeded up; the tense situation of powersupply and demand was alleviated; the safety and reliability of power productionwere improved; the management on power tariff was standardized; environmentalprotection and energy conservation achieved good results; researches on newtechnologies made new achievements; and the operation of enterprises was im-proved.

一汽-大众奥迪连续四年蝉联J．D．Power销售及售后服务满意度双料冠军

近日，JDPOWer亚太公司发布2016年中国售后服务满意度研究（CSI）报告，一汽-大众奥迪再次拔得豪华车市场头筹，这也意味着奥迪连续四年蝉联JDPower中国汽车销售满意度研究SM（SSI）和中国售后服务满意度研究SM（CSI）豪华车品牌双料冠军，显示了客户极高的认可度。至此，一汽-大众奥迪以19次冠军的成绩当之无愧地成为中国豪华车市场摘得冠军总数最多的品牌。

一汽-大众奥迪连续四年蝉联J.D.Power销售及售后服务满意度双料冠军

近日,J.D.Power亚太公司发布2016年中国售后服务满意度研究SM（CSI）报告,一汽-大众奥迪再次拔得豪华车市场头筹,这也意味着奥迪连续四年蝉联J.DPower中国汽车销售满意度研究SM（SSI）和中国售后服务满意度研究SM（CSI）豪华车品牌双料冠军,显示了客户极高的认可度。

1K-50型果园开沟机开沟部件功耗影响因素分析与试验

为探明1K-50型果园开沟机工作参数和双旋耕刀辊结构参数对作业功耗的影响规律,该文建立了分析开沟部件功耗的切土,运、抛土力学模型,得到了开沟部件功耗与整机工作参数、刀辊结构参数以及土壤力学性能之间的函数关系。搭建了基于土槽试验台的开沟部件功耗测试装置,模拟坚实度为950kPa的葡萄园土壤环境,以刀辊转速、前进速度、开沟深度和刀辊型式为试验因素,进行单因素试验和多因素正交试验,测得旋耕刀辊在不同结构和工作参数下的功率消耗,得到影响开沟部件功率消耗的因素主次顺序为刀辊型式>前进速度>刀辊转速>开沟深度,其功耗较优参数组合为采用D3型刀辊,刀辊转速为150r/min,前进速度为0.06m/s,开沟深度为0.15m,测得此时开沟部件平均功耗值约为1.22kW。将装置正交试验表中各因素值代入功耗解析式,利用MATLAB软件进行数值计算与分析,得到影响功率消耗因素的主次顺序与台架试验结果相同,求得功耗理论值与试验值的相对误差百分比最大为12.86%,最小为2.00%,验证了功耗理论模型具有较高的准确性。该研究可为机具改进和小型林果园开沟机的设计提供参考。

液压机械无级变速器全工况效率模型及功率损失分析

针对目前液压机械无级变速器(hydro-mechanical continuously variable transmission,HMT)效率模型研究中存在的效率组成不全面、局限于单一工况以及缺少功率损失分析等问题,该研究建立了考虑传动元件及附件功率损失的HMT全工况效率模型。首先建立HMT变量泵-定量马达的通用效率模型,根据效率试验数据辨识相关参数;然后建立HMT其他传动机构及附件的效率模型,将各部分效率模型组合得到完整的HMT效率模型。基于自主研发的HMT进行计算,得到全工况效率图和各组成机构的损失功率。搭建试验台,对HMT进行效率试验以验证模型的准确性,HM1段和HM2段在全工况下的效率平均绝对误差分别为0.027 3和0.026 1,相较于对比方法准确性提高了64.59%和55.46%。结合效率图和功率损失情况分析HMT效率特性和影响因素,结果表明:1)本文HMT效率主要受负载和液压单元排量比e影响,输入转速影响不显著;2)低负载下本文HMT效率主要影响因素为负载,高负载下为排量比;3)泵马达功率损失对HMT效率影响最大,e <0时液压损失功率大,HMT效率低;e=0时液压损失功率为0,HMT效率达到最高;4)齿轮和离合器的功率损失对HMT效率的影响不容忽略,考虑其他附件功率损失有利于提高模型计算精度。提高HMT效率的措施:1)尽量避免HMT长时间在功率循环工况下工作,在优先满足负载需求和保证发动机经济性前提下,推荐在纯机械点及其附近工作点作业;2)避免长时间低负载作业,应保持在高负载工况作业;3)选用高效率液压单元或通过改进参数提高液压单元传动效率;4)满足齿轮和离合器性能要求前提下改进参数,降低功率损失。

基于波长选择方法Modeling Power的黑木耳产地判别研究

应用近红外光谱技术结合波长选择方法(modeling power,MP)实现了黑木耳产地的快速准确判别。共收集4个产地240个黑木耳样本,通过光谱扫描,建立了最优的偏最小二乘(PLS)判别模型。同时应用MP选择对黑木耳产地判别的有效波长,作为输入变量,建立最小二乘-支持向量机(MP-LS-SVM)模型。比较了3种MP选择波长的阈值方法,分别为MP值大于0.95,0.90和(0.90+Peak),并建立了相应的MP-LS-SVM模型。以预测集样本的准确判别率作为模型评价标准,分别设定预测的残差绝对值标准0.1,0.2和0.5。预测结果表明,MP-LS-SVM(0.90+Peak)模型在残差标准为0.1,0.2和0.5时的判别效果均为最优,正确判别率分别为98.3%,100%和100%。说明ModelingPower是一种非常有效的波长选择方法,应用近红外光谱技术结合MP-LS-SVM进行黑木耳产地判别是可行的,并获得了满意的判别精度。

乙醇燃料SI-HCCI-SI燃烧模式发动机的工作区域

为了研究火花点火和均质压燃两种燃烧方式的转换,在一台ZS1105柴油发动机的基础上通过改变压缩比、燃料供给方式和进气系统,采用进气预热成功实现了HCCI和SI两种燃烧方式的转换。试验结果表明:所开发的双燃烧模式发动机运行可靠,可方便地实现火花点火和均质压燃两种燃烧方式的转换,可作为研究这两种燃烧方式转换的平台。确定了乙醇燃料HCCI工作区域的上、下边界判断方法,得到了乙醇燃料SI-HCCI-SI燃烧的工作区域。

生物柴油-柴油-丁醇燃料喷雾与燃烧过程可视化实验

采用可视化定容燃烧器模拟发动机高温、高压环境,利用高速摄像机和铜蒸气激光器,拍摄记录生物柴油-柴油-丁醇混合燃料整个雾化与燃烧过程。对可变高温、高压实验环境下不同掺混比例的燃料液态贯穿距和放热率进行测量。实验结果表明:环境温度800K和900K时,B10D80N10燃料喷射过程中发生微爆,油束末端破裂、发散成羽状,导致液态贯穿距离突然降低。随着环境温度的升高,燃烧过程逐渐由预混合燃烧向扩散燃烧转变,微爆现象也随之减弱或消失。

2011-2015年河南省农业机械总动力的预测

农业机械总动力是衡量农业机械化水平的一项重要指标。对河南省农业机械总动力进行预测,将为农业机械化部门制定合理的发展规划提供一定的理论支持,同时也为农机企业了解未来市场需求状况提供一定的参考。以1991-2010年间的河南省农业机械总动力统计数据为基础,利用BP神经网络建立了河南省农业机械总动力的预测模型。该模型采用3层BP神经网络,输入层、隐含层和输出层的神经元数目分别为5,13和1。隐含层和输出层的激励函数分别为正切型与对数型Sigmoid函数。采用分步预测的思想,利用自适应学习速率训练方法对该网络进行了训练,获得了该模型中各层之间的连接权值和各层神经元的阈值。利用该模型对现有数据进行了仿真预测,结果表明,该模型具有较高的预测精度。在此基础上,对河南省"十二五"期间的农业机械总动力进行了预测,并给出了预测数据。

柴油机高密度-快速燃烧过程数值模拟

针对柴油机升功率提高后燃烧过程的变化,应用CFD软件Fire研究燃烧子模型在柴油机高密度-快速燃烧过程模拟中的应用,利用某高升功率单缸柴油机的试验结果对WAVE喷雾破碎模型和涡团破碎(EBU)湍流控制燃烧模型的关键参数进行标定。对柴油机3 600 r/min时全负荷条件下燃烧过程进行数值模拟,仿真结果表明,缸内平均压力、指示功率和放热率与试验结果吻合良好,缸内燃油蒸发充分、温度分布均匀,验证了CFD模型模拟柴油机高密度-快速燃烧过程的有效性。