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.     

利用RBF神经网络预测和消弱低频无线电导航定位误差

由于诸多因素的影响，导致了低频无线电导航系统的定位误差和GPS卫星导航系统的定位误差之间存在较大的差距，拟采用径向基函数（RBF）网络来预测电波传播误差，以期达到修正现有低频无线电导航系统定位误差的目的，从而进一步提高低频无线电导航定位的精度。     

儿童慢型克山病的自然病程

为了探讨儿童慢型克山病的自然病程和预后危险因素，本文分析了长期随访的儿童慢型克山病６３例，结果表明：①儿童慢型克山病预后差，其１年存活率５０．５％、５年仅１５．８％；②自然慢性发病、有奔马律、心功能Ⅲ级以上，心电图心室增大，Ｘ线心胸比率重度扩大者，５年存活率低（Ｐ＜０．０５或０．０１）。     

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.     

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。     

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.     

钢管拱肋微膨胀混凝土压注技术

拱肋压注混凝土施工在拱桥施工中是一个很重要的环节。介绍拱肋混凝土的压注工艺和方法,包括选材、混凝土配合比的设计,混凝土的拌制、运输等。可供借鉴。     

基于模糊理论的岚山港液体石油化工品码头建设方案优选研究

基于模糊理论和层次分析法,在合理确定指标集、评语集、权重集和评价矩阵的基础上,构造了岚山港液体石油化工品码头建设方案优选的二级模糊综合评价模型,并应用该模型选出了最佳工程方案,验证了该方法的有效性和合理性。     

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.