A Novel Image Encryption Technique Based on Inter Block Difference

Data security plays a vital role in the current scenario due to the advanced and sophisticated data access techniques.Present development in data access is alwa...     

Fleet deployment optimization for liner shipping: an integer programming model

Extending and improving an earlier work of the second author, an Integer Programming (IP) model is developed to minimize the operating and lay-up costs for a fleet of liner ships operating on various routes. The IP model determines the optimal deployment of an existing fleet, given route, service, charter, and compatibility constraints. Two examples are worked with extensive actual data provided by Flota Mercante Grancolombiana (FMG). The optimal deployment is solved for their existing ship and service requirements and results and conclusions are given.     

带功率因数补偿的单相半控桥整流器(二)

介绍了绘制正弦线电流的开关模式单相半控桥整流器,用它来获得功率因数补偿并保持直流环节电压的恒定.在该整流器中使用4个有源开关,以便在交流端电压上产生单极脉宽调制(PWM)电压波形.与中性点箝位变流器(NPC)相比,该整流器没有箝位二极管也能实现三点式PWM控制.控制电路采用两个控制回路:外部控制回路用比例积分电压控制器调整直流环节电压,采用相位闭环电路产生与电源电压同相的正弦波形来实现功率因数补偿.在内部控制回路中,用基于载波的电流控制器跟踪线电流信号.为补偿由于负载变化所引起的中点电压,控制电路采用中点电压补偿器.该整流器的交流侧可产生3个电压电平,并用计算机仿真与试验结果验证了控制算法的有效性.     

Union rivalry and crew reform in shipping: A United States—Australia comparison

The national-flag fleets of most of the traditional martitime nations have, in virtually every case, been in decline in the 1980s and 1990s, despite the continued growth of ocean shipping. They have declined in terms of numbers of vessels and numbers of sea-going jobs, although not necessarily in terms of cargo carried. However, a number of those nations have responded to the changed technological and competitive conditions with some success by attempting to adjust crewing and work practices on vessels at sea. Neither the USA nor Australia has been in the forefront of such change. However, considerably more progress has been made in modernizing crewing practices and work rules in the Australian-flag fleet than in the US-flag fleet. There are a variety of reasons for this, inluding government policy. However, it is our argument that one of the principal reasons the US fleet lags behind the Australian fleet in the adoption of modern crewing practices and work rules is the much greater degree of union rivalry in the US shipping industry. In fact, while the degree of fragmentation and rivalry among unions in the Australian flag fleet has declined dramatically since 1980, their US cousins have continued, and in some ways expanded, their pattern of fratricidal behavior. First we shall discuss some of the technological and competitive imperatives that are driving human resource management practices in shipping and the crewing and industrial relations adjustments that are being made around the world to adjust to them. Then we shall indicate how the Australian and US fleets have responded to these challenges. This will be followed by a discussion of unionism in the Australian and US maritime industrics as it has devloped in the last two decades of the twentieth century. Finally, we shall draw conclusions about the impact of different patterns of unionization.     

Real-Time Fuzzy Obstacle Avoidance Using Directional Visual Perception

This paper presents a novel vision-based obstacle avoidance approach for the Autonomous Mobile Robot (AMR) with a PanTilt-Zoom (PTZ) camera as its only sensing modality. The approach combines the morphological closing operation based on Sobel Edge Detection Operation and the (μ-kσ) thresholding technique to detect obstacles to soften the various lighting and ground floor effects. Both the morphology method and thresholding technique are computationaUy simple. The processing speed of the algorithm is fast enough to avoid some active obstacles. In addition, this approach takes into account the history obstacle effects on the current state. Fuzzy logic is used to control the behaviors of AMR as it navigates in the environment. All behaviors run concurrendy and generate motor response solely based on vision perception. A priority based on subsumption coordinator selects the most appropriate response to direct the AMR away from obstacles. Validation of the proposed approach is done on a Pioneer 1 mobile robot.     

俄罗斯铁路解决机车不足的问题

至2010年前俄罗斯将淘汰大部分旧机车,但据估计其货运量到2010年将增加26%,客运量增加6%～7%.为满足运输量增长的要求,俄罗斯铁路需要约6 800台电力机车和6 500台内燃机车.文章介绍了俄罗斯制定的机车战略决策.     

Modelling and Control of an Automated Vehicle

We present a vehicle model that includes the vehicle dynamics and a vehicle tire model. The model developed is then used for conducting steering analysis of an automated vehicle. We test the developed model on a step lane change maneuver and propose a model-reference based controller for remote control of a vehicle. Stability analysis of the closed-loop system using die Lyapunov approach is included.     

The social psychological consequence of a life at sea: A causal model

This paper explores the influence of this occupation on alienation and social integration of its members. Data were collected using a survey instrument from a sample of 293 seamen, both officers and crew. Factors determining variance in levels of alienation are examined using multiple regression technique. Results indicate that variance in several occupational features of life at sea affect the degree of alienation experienced by seamen, and a number of social characteristics were found to mitigate these influences. Supplementary qualitative data are also used.     

The effects of marine cargo delays in law and commerce

With the development of door-to-door intermodal services and the advent of just-in-time supply systems, punctual delivery of cargoes is more than ever a priority both for shippers and for shipowners. This paper is about the incidence of delay in transportation, particularly in the marine mode, and its legal and commercial consequences.

The fundamental legal obligations of marine carriers have always included delivery with dispatch. Thus the law would seem to support the commercial expectations of shippers for reliable performance. The authors discuss the nature of these obligations, investigate their adequacy under modern conditions of trade and report on a survey of Canadian shippers and consignees.

The authors conclude that there appears to be a divergence in the toleration of delay, but that few of the Canadian companies suffering unacceptable delays received, or even sought, financial compensation and none of them planned to do more. The authors speculate about their reasons for absorbing the losses incurred through unacceptable delays. The evidence from the survey is that shippers, in spite of their dissatisfaction with the resolution or outcome of incidents of unacceptable delay, are loath to seek compensation through legal means, but instead prefer to resort to a range of commercial actions.