Experimental investigation of evaporation rate and exhaust emissions of diesel engine fuelled with cotton seed methyl ester and its blend with petro-diesel

An experimental study to measure the evaporation rates, engine performance and emission characteristics of cotton seed biodiesel (cotton seed oil methyl ester) and its blends in different volumetric proportions with diesel is presented. The thermo-physical properties of all the fuel blends have been measured and presented. Evaporation rates of neat cotton seed biodiesel, neat diesel and their bends have been measured under slow convective environment of air flowing with a constant temperature. Evaporation constants have been determined by using the droplet regression rate data. The neat fuels and fuel blends have been utilized in a test engine with different load conditions to evaluate the performance, combustion and emission characteristics of the fuels. The specific fuel consumption values of the two blends, viz. B25 and B75 are found to be same. At the highest load, B0 records the lowest CO volume followed by B100. From the observed evaporation, performance and emissions characteristics, it is suggested that a blend of B50 and B75 can be optimally used in standard diesel engine settings.     

基于Matlab油船意外泄油性能的程序设计

基于概率方法的意外泄油性能参数计算是2010年1月1日及以后新造船破舱稳性需要评估的性能之一,满足一定的衡准要求方可。根据油船的分舱分别进行船底破损概率和船侧破损概率的插值,然后按照一定的公式求出船底破损后与船侧破损后的泄油量的加权之和,即意外泄油性能参数。由于手工计算费时费力,文章基于Matlab平台,开发了意外泄油性能参数的自动计算程序模块。计算结果与文献结果相比较,证明了本程序的计算精度,具有较好的工程实用价值。     

Centrifuge modelling of pipe-soil interaction in clay with crust layer

Seabed in regions, such as the Gulf of Guinea and North West Shelf of Australia, may exhibit a crust layer where the undrained shear strength can be an order of magnitude higher than that of the immediately underlying sediment. This can complicate design of steel catenary risers, where fatigue depends on the cyclic vertical stiffness of the pipe-soil interaction. Potential punch-through of the riser into the underlying soft soil may invalidate design assumptions based on the pipe-soil stiffness within the crust layer. The long-term evolution of pipe-soil stiffness within the crust layer, which exhibits similar properties to an over-consolidated soil, is also poorly understood. This paper describes centrifuge model tests undertaken in a clay sample with a crust layer, simulating the punch-through process of a pipe under load control and investigating the pipe-soil stiffness during long-term cyclic loading tests under displacement control. Results confirm that the potential for punching-through the crust layer depends strongly on the relative ratio of pipe diameter to crust layer thickness. The long-term evolution of pipe-soil stiffness showed a steady increase after an initial remoulding stage in contractile soils (normally consolidated and lightly over-consolidated), but a steady reduction in the heavily over-consolidated, more dilatant, crust. The magnitude of pipe-soil stiffness changes (during both remoulding and reconsolidation) is governed by the over-consolidation ratio of the soil and the amplitude of the cyclic displacements. This study provides insights on the relevant cyclic stiffness to consider when assessing SCR fatigue life in over-consolidated soils and soils exhibiting a superficial crust layer.     

Strain prediction for critical positions of FPSO under different loading of stored oil using GAIFOA-BP neural network

FPSO (floating, production, storage and offloading) units are widely used in the offshore oil and gas industry. Generally, FPSOs have excellent oil storage capacity owing to their huge oil cargo holds. The volume and distribution of stored oil in the cargo holds influence the strain level of hull girder, especially at critical positions of FPSO. However, strain prediction using structural analysis tools is computationally expensive and time consuming. In this study, a prediction tool based on back-propagation (BP) neural network called GAIFOA-BP is proposed to predict the strain values of concerned positions of an FPSO model under different oil storage conditions. The GAIFOA-BP combines BP model and GAIFOA which is a combination of genetic algorithm (GA) and an improved fruit fly optimization algorithm (IFOA). Results from three benchmark tests show that the GAIFOA-BP model has a remarkable performance. Subsequently, a total of 81 sets of training data and 25 sets of testing data are obtained from experiment using fiber Bragg grating (FBG) sensors installed on the surface of an FPSO model. The numerical results show that the GAIFOA-BP is capable of predicting the strain values with higher accuracy as compared with other BP models. Finally, the reserved GAIFOA-BP model is utilized to predict the strain values under the inputs of a 10-day time series of volume and distribution of stored oil. The predicted strain results are further used to calculate the fatigue consumption of measurement points.     

某船右主机不能正常建立滑油压力的故障排除

文章对某船右主机启动过程中,机带滑油泵不能正常建立滑油压力进行了分析,制定了针对性的排除故障措施,通过在机带滑油泵通舱管吸入口处安装吸入止回阀解决了滑油压力非正常下降的故障,实船应用证明措施合理,对同类故障排除有较好的借鉴意义。     

从一起船舶主机拉缸故障谈柴油机润滑油的选用

通过某LPG船一起主机拉缸案例,阐述船舶柴油机润滑油合理选用和管理的重要性,讨论选用润滑油应根据船舶柴油机的型号、燃油品质等具体情况,充分考虑润滑油的黏度等级和碱度。介绍船用柴油机润滑油国内外主要生产商及其相应的产品牌号。     

中韩船舶油污损害赔偿制度的比较

韩国不论是从地理位置还是经济贸易往来,对于我国是很重要的邻国.由于海上运输的国际性,我国的船东有在该国卷入油污损害赔偿案件的可能,研究其油污损害赔偿制度能够更好的保护我国船东的权益,而且对于我国完善油污民事赔偿立法有一定的借鉴作用.本篇论文比较了中韩油污损害赔偿制度,并对完善我国油污损害赔偿制度提出几点建议.     

A study on the stability of a motorcycle wheel–swingarm suspension with chain transmission

The present study describes a possible driving mechanism for a self-excited oscillation observed in motorcycle dynamics, often referred to as chatter. This phenomenon, affecting the performance of road racing motorcycles, has been simulated in straight running braking manoeuvres with multibody motorcycle models. It involves rear suspension bounce and driveline oscillation in the frequency range between 17 and 22?Hz. A simplified model of a motorcycle rear suspension with chain transmission is proposed and its stability in equilibrium configurations is studied via eigenvalue analysis. The sensitivity with respect to all its governing parameters is analysed by means of stability maps and the self-excitation mechanism is explained with the aid of energy balance analysis and phase diagrams. It is found that the key role for the instability onset is played by the gradient of the nonlinear characteristic slip function of the tyre.     

柴油机起动过程缸内窜机油现象的可视化研究

在单缸机上利用内窥镜技术观察到了起动过程中缸内有窜机油的现象。采用图像分析和试验验证相结合的方法,分析了缸内窜机油现象发生的原因,研究了转速和进气压力对柴油机起动倒拖工况下缸内窜机油现象的影响,研究了起动着火运行时缸内的窜机油现象以及炭烟排放特性。研究表明:柴油机高转速起动倒拖工况下,在压缩上止点前后以及排气上止点后均有机油窜入缸内;当转速升高时,窜入缸内的机油量增加;当缸内压力升高时,窜入缸内的机油量减少;在起动着火过程中,运行初期缸内出现窜机油现象,随着发动机运行时间增加,窜机油现象消失,炭烟减少。     

英语影视教学的课堂组织技巧

本文从外语教学理论分析了影视教学的可行性,并阐述了影视教学目的和策略,再以学生为中心的英语教学模式深入探讨影视教学的课堂组织技巧,最后以美国电视剧《Friends》为例阐述了具体的课堂设计和安排。通过探讨英语影视教学过程中的技巧,说明影视教学作为一种现代教学手段,应该积极且有效地引入到大学英语教学中。