Study on the methods of precision controlling for the manufacture of hull curvature sections

The precision controlling technology is a key step for the modern ship construction, with the precision controlling of the ship-hull curvature as one of bottlenecks in shipbuilding, where the initial is to present a compensation value for the ship-hull plate precisely. The compensation value of the curvature plate is composed of two parts: the construction compensation, which results in the process of heating construction of curvature plate, and the assembling compensation, which results in welding ribbed stiffeners onto the curvature plate. Based on the developed computation system for the local contraction value, this paper presents a method to establish the experimented samples for the assembling compensation by means of numerical experiments, and another method to establish the practical mathematical model for the construction compensation of curvature plate. Furthermore, it introduces the experimental measuring method for the assembling compensation of the curvature plate, based on which the related database system has been developed. Numerical examples are analyzed to demonstrate the process to establish mathematical model for the assembling compensation values.

A rate-based robust queue management system through multi-loop internal model controller with initial value compensation

An efficient congestion control approach should gain weighted fairness and also robustness against external disturbances.Moreover,variations in the number of active sources cause a network to operate as a switched system in which the initial values affect the transient response.The main contribution of this article is to design a rate-based adaptive robust queue management contemplating the initial value compensation(IVC).The congestion is avoided via Two-Degree-of-Freedom Internal Model Control protocol as a robust procedure.The utilisation factors are designated according to the delay of each source(weighted fairness)in which the sources will use the maximum value of the bottleneck capacity(maximum utilisation).On the other hand,the number of the users is determined adaptively and effects of non-zero initial values are eliminated through a protocol called IVC.Simulation results through Network Simulator 2 and Simulink software confirm the analytical results and the efficacy of the proposed method.

Ecological compensation mechanism for urban green land and its application in Shanghai, China

Urban green land compensation plays an impor-tant role in county development,ecological environment management and many other fields.The concept,methods and principles of urban green land are introduced in this paper.According to the pay fee method,the value and ecological function of various types of urban green land were analyzed.The cost-benefit analysis method(CBAM)was used to estimate different external diseconomy benefits caused by green land loss.The authors applied CBAM to estimate such benefits in the case of Shanghai,China,and calculated the actual compensation value for green land.Results indicated that in 2002,the compensation value for the green land of Shanghai was RMB 8.58×10^(5) Yuan/hm^(2).