The Nigerian shipping industry and indigenous shipping companies

The shipping industry in Nigeria since the early 1990s has been experiencing a continuous disastrous downturn. Nigerian shipping companies' participation in international shipping has continued to be very limited. Their presence and impact is hardly felt in the world's shipping industry. Both the national carriers (that is shipping companies with national carrier status) and other indigenous private shipping companies have vessel as well as management problems. These problems have led to the poor performance of the Nigerian shipping industry for over a decade now. The carriers in the industry are not attaining for the country the gains that are supposed to emanate from shipping. This paper points out the importance of shipping to a nation, identifies the problems the country's shipping companies are facing and proffers solutions that include merging of the companies to have strong financial standing and a competitive edge.     

Intra-Platoon Collision Behavior during Emergency Operations

This paper presents current research regarding intra-platoon collision dynamics for rapid decelerations. Measures of ride quality and impact severity are introduced to allow comparisons between different collision scenarios. In this study, the disturbance input to the platoon is assumed to be a rapid braking of the lead vehicle. Several deceleration rates are used to assess the overall platoon behavior and the effect of the intra-platoon collisions on the platoon passengers. The role of the desired headway spacing on preventing the occurrence of intra-platoon collisions and improving rider comfort is discussed.     

带空间管系的船舶水泵机组隔振浮筏性能研究

基于船舶水泵机组隔振浮筏这种多挠动源的系统,探讨了浮筏装置所具有的特性以及隔振设计技术.利用有限元法数值模拟了隔振系统忽略和计及管系下的两种模型,综合分析了空间管系对浮筏隔振系统隔振性能的影响,并就管路和机组间刚性连接和多种弹性连接下系统隔振性能作了对比分析.分析结果表明,空间管系减弱了系统的隔振性能,在动力设备和管路间使用挠性接管等弹性连接可大大减小管系的影响.文中探讨了水泵机组的隔振设计技术以及为了提高隔振性能而应注意的若干方面.     

论二阶Euler—Lagrange方程的形式和结构

本文讨论m个变元情形,得到结论:m≥2时,二阶方程为Euler-Lagrange方程的充要条件是它为Monge-Ampere方程,其系数满足某些条件。     

无公用轴独立旋转车轮转向架直线横向动力学研究

无公用轴独立旋转车轮转向架的车辆不仅左右车轮的旋转自由度独立,而且两轮的横移和摇头也解耦。文章通过建立无公用轴独立旋转车轮转向架车辆在直线上的横向动力学客车模型,模拟实际线路,利用新型数值快速积分法进行动态仿真,得出无公用轴独立旋转车轮转向架车辆的动态响应值,并与具有相同悬挂参数的传统客车进行比较。     

Effect of fatigue strain range on properties of high-strength structural steel

Ship hulls are built with stiffened steel plates and experience continuous fatigue load cycles when in service. Mechanical properties of the steel are expected to change due to the application of these cyclic loads. Therefore, the mechanical properties of the material at various levels of fatigue damage need to be understood. This paper presents two test series that were conducted to determine the effect of two different strain ranges (2000 and 3000 micro strains) of fatigue cycles on the mechanical properties of high-strength structural steel. The test results indicate that the cycle-dependent behaviours of the material can cause a slight increase or a significant decrease in the yield strength when compared to its virgin state. However, the ductility of the steel does not change much as the strain cycle increases.     

新型排水管在杭州湾新区基础设施建设中的应用

杭州湾新区的地质状况为盐碱性软土地基,在该地区的基础设施工程中,若采用传统管材,会产生易腐蚀、使用寿命短、维护工作量大等弊病。该文结合工程实例,论述新型管材取代传统管材所取得的经验和效益。     

Effects of information in road transport networks with recurrent congestion

This paper aims to gain more insight into the implications of information provision to drivers on the performance of road transport networks with recurrent congestion. For this purpose, a simulation program consisting of three components has been written. The first component is the traffic simulation model, the second component is the information provision mechanism, and the third component monitors the behavioural decision-making process of the drivers, which is modelled using a utility-based satisficing principle. Three types of information provision mechanisms will be considered: information based upon own-experience, after-trip information and real-time en route information. The findings in this paper, obtained in a hypothetical context, underline the important relationship betweenoverreaction, thelevel of market penetration and thequality of the information. High quality information allows a high level of market penetration, while low quality information, even when provided at low levels of market penetration, induces overreaction. Furthermore, real-time en route information is in particular beneficial during the process leading to a steady state; it reduces the variance in travel time considerably. The paper concludes with a discussion on the market potential of motorist information systems when commercially marketed.     

SLENIUM FROM BEEF IS HIGHLY BIOAVAILABLE AS ASSESSED BY LIVER GLUTATHIONE PEROXIDASE （EC1．11．1．9） ACTIVITY AND TISSUE SELENI

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