宽带氧传感器用于发动机失火检测的研究

介绍了一种使用宽带氧传感器进行发动机失火检测的方法,在发动机各种工况下对该方法的有效性进行了试验研究.试验结果表明,使用氧传感器信号的差分信号可以更清楚地从正常燃烧中辨别出失火,差分信号波动的幅值可作为失火检测的监测参数.由于氧传感器的反应速度随发动机转速的增加而增加,因而该方法可以检测高速(5 500 r/min)工况下发生的失火.     

充电桩产业发展的模式探索——以城市交通企业发展充电桩产业为例

在政府对电动汽车产业的大力推动下,我国电动汽车产业已步入快速发展期,作为电动汽车基础配套设施建设的充电桩也呈井喷式增长,未来充电桩设施建设将会成为交通企业产业链的重要环节,本文就充电桩产业发展现状和城市交通企业进军充电产业模式进行简要分析和研究。     

Neural network-based fuel consumption estimation for container ships in Korea

ABSTRACT

Due to the outstanding strength of advanced machine-learning techniques, they have become increasingly common in predictive studies in recent years, particularly in predicting ship energy performance. In constructing predictive models, prior studies have mostly employed vessels’ technical parameters to establish machine-learning algorithms. To bridge this research gap and enable wider applications, this paper presents the design of a multilayer perceptron artificial neural network (MLP ANN) as a machine-learning technique to estimate ship fuel consumption. We utilized the real operational data from 100–143 container ships to estimate fuel consumption for five different container ships grouped by size. We compared the performance of two ANN models and two multiple-regression models. Four input parameters (sailing time, speed, cargo weight, and capacity) were included in the first ANN and the first regression model, while the other two models only consider two inputs from physical function. The mean absolute percentage error of the ANN models with four inputs was the smallest and less than those in extended statistical models, demonstrating the MLP’s superiority over the statistical model. The MLP ANN model can thus be applied to confirm the effectiveness of the slow-steaming method for achieving energy efficiency.     

Application of a real-coded genetic algorithm for the fitting of a ship hull surface through a single non-uniform B-spline surface

In digital ship-design processes, surface modeling needs to be as accurate as possible for effectiveness in ship production as well as numerical analysis of the performance. Traditionally, the form of a ship hull is constructed from a set of cross-sectional data. This approach entails difficulties in the cross-sectional spacing and accuracy of the characteristic curves, such as the stern and bow profiles, deck side line, bottom tangential line, and unconnected curves. Genetic algorithms (GAs) have attracted increasing attention as a multimodal optimization solution for surface reconstruction that enable construction of a single non-uniform B-spline (NUB) surface at the initial stage of ship design with constraints such as knuckles, discontinuity conditions, and bulbous bows with high curvatures, . The first, simultaneous multi-fitting GA determines the boundary curves, such as the stem and stern profiles, and finds the common knot values for both curves. Similarly, the same GA technique is applied for other boundary curves at the bottom and the deck. The second GA is employed to fit the interior data points after the boundary curves are fitted. The encoded design variables for surface construction are the locations of the vertices and the knot values. Those variables are modified for improving the surface quality until a predefined degree of precision is attained. In four instances of application, the GA technique developed in this research has been shown to provide good, single, NUB surfaces with high efficiency. In the early design stage, a single NUB surface is more convenient for performance visualization and finite-element methods. It can be readily translated into many CAD/CAM packages, which facilitate the smooth transition of data across the different design stages.     

Response of the Black Sea mean level to atmospheric pressure and wind forcing

The response of the Black Sea mean level to atmospheric pressure (AP) and wind forcing is investigated using 5 years of TOPEX/POSEIDON (T/P hereafter) data. A coherence analysis is first applied to mean sea level and pressure to examine the validity of the inverse barometer (IB) approximation over this area. As expected, it reveals very significant deviations from an IB response attributed to the narrowness of the Bosphorus Strait and its limiting role in water exchanges. A comparison is drawn with the Mediterranean Sea case. A single basin version of the Candela analytical model [Candela, J., 1991. The Gibraltar Strait and its role in the dynamics of the Mediterranean Sea. Dyn. Atmos. Oceans 15, 267–300], which takes linear friction at the strait into account, is then used. The model explains a significant part of the T/P mean sea level variance (about 30%, while the IB correction only explains 5% of its variance) and provides a means to correct the altimeter data for the pressure effect much better than the standard IB effect. The response of the mean sea level to wind forcing is then analysed. Coherence analysis between sea level and along-strait wind stress (WS) reveals a significant coherence at periods ranging from 40 to 100 days, with an almost steady phase of 270°. This result is confirmed with a multiple coherence analysis (mean sea level vs. WS and AP). A plausible mechanism is a piling-up of water at the northern or southern end of the strait due to along-strait wind forcing. The associated along-strait pressure gradient would modify the barotropic flow in the strait and then the mean sea level. Using an extension of the Candela model, we show that this mechanism is consistent with T/P mean sea level observations.     

Influence of residual stresses and geometric imperfections on the elastoplastic collapse of cylindrical tubes under external pressure

The buckling problem of a circular cylindrical shell has long been widely investigated due to its great importance in the design of aerospace and marine structures. Geometric imperfections and residual stresses are inevitable in practice and have been so far frequently considered in analytical and numerical predictions. But little attention has been paid until now on the combined influence of such initial defects on the critical and often unstable response of such elastoplastic structures. In this paper, a shell finite element is designed within the total Lagrangian formulation framework to deal with the elastoplastic buckling and post-buckling of thin cylindrical tubes under external pressure and axial compression. A specific experimental process will be introduced in order to measure residual stresses in the shell very accurately, so as to include them in the numerical calculations. The present formulation will enable us to describe the complete non-linear solutions, namely the critical pressures (bifurcation and limit (collapse) loads), the bifurcation modes and the bifurcated equilibrium branches up to advanced post-critical states. Comparisons will be made between numerical results and the experimental critical value and deformation patterns of a new generation profiler. Furthermore, the combined effects of geometric imperfections, residual stresses and plasticity will be analyzed.     

铁路罐车罐体外观和标记检查的重要性

在进行罐车检定和罐体安全检测时,准确判断罐体标记是否准确对罐车检定工作十分重要,同时还要对罐体进行外观检查,确定外表面是否有明显的腐蚀、损伤和变形。车辆型号和封头形式对罐体型号的判断有影响。企业名称、车型、车号、载重、自重、容积、容积表号和介质名称等所有罐体标记是否准确,影响着检定工作的准确和检定证书的可靠有效。举例说明在日常检定工作中遇到的情况及处理方法。     

基于GPRS的长途客车远程监控系统的设计研究

随着社会经济的发展和公路网的不断建设,我国长途客运业也得到了迅猛的发展,但是长途客运车辆交通事故屡屡发生,本文提设计了一种基于GPRS的长途客车监控系统,它是利用卫星定位技术,无线通讯技术,谷歌地图技术和图像压缩等相关技术,且在Visual Basic 6.0开发平台上而完成的,该系统将采集到的车辆GPS信息、车内图像信息以及报警等信息通过GPRS网络发送到监控中心,实现监控中心对运行中长途客车的监控,以确保长途客车安全运行。     

车辆出颠簸路第一脚无制动故障分析

车辆在行驶一段颠簸路后出现第一脚制动效能低或无制动效能故障,经现场查看及故障件台架测试等方法排查,确定制动钳上固定钳体和支架的弹性卡箍脱落是故障发生的原因。通过优化卡箍空间走向、改进加工工艺、优化材质等方法,解决脱落问题。整改后的样件通过实车搭载试验验证,解决了车辆出颠簸路后第一脚无制动效能问题,保证了路试过程中制动系统的可靠性和安全性。     

利用遗传算法识别汽车轮胎魔术公式参数

汽车轮胎动力学模型的准确度对汽车运动仿真的精度影响很大。汽车轮胎魔术公式是一种精度较高的轮胎模型。利用遗传算法的非线性优化特点,对汽车轮胎纯滑移魔术公式参数进行识别,并讨论算法参数对参数识别的影响。识别结果,纵向力和侧向力的相对残差在5%左右,回正力矩的相对残差在10%左右。