焊后热处理对15MnMoVNXt、HQ80、stE690钢HAz冲击韧性的影响

本文针甘15MnMOVNXt、HQ80、StE690三种钢焊接接头,采用 300~70oeC内不同温度回火,600“C2.5~6。sh不同回火时间,以及 不同冷却方式研究焊后热处理对HAz韧性的影响,为实际生产提供制 定工艺的依据。      

The stabilization control of underactuated surface vessels

The problem of stabilization control of underactuated surface vessels with two independent control inputs is in vestigated inthis paper. Through transformation, a cascade property of the system is revealed. And the original nonlinear system could be divided into two subsystems: a linear subsystem and a nonlinear subsystem. The stabilization laws are derived for the two subsystems separately. A smooth time - varying feedback stabilization law with exponentially convergence rate is obtained. The proposed stabilization law guarantees all the system states converge to the equilibrium exponentially. The aim of stabilization control of underactuated surface vessels is achieved. At last, the effectiveness of the proposed algorithm is illustrated by simulation tests.     

Reliable routing algorithm in marine ad hoc networks

A routing algorithm called DNH for increasing efficiency of mobile ad hoe network is presented, which is based on a new cflteflon called TSS (Temporarily Steady State), combining with wireless transmission theory that makes networks topology correspondingly stabilization. Also the DNH algorithm has the characteristics of giving up queuing in a node, but selecting another idle node instead of the node for forwarding data packets if the node has a full throughput. Simulation evaluation shows that selecting another node is better than queuing in a full throughout node if some conditions are satisfied, especially during a sea battle, every warship in ad hoe network wants to contest time and increase propagation reliability. The DNH algorithm can help decrease routing time, and raise efficiency of marine ad hoe networks.     

Special requirements for alumina ceramic of ESG electrode bowl

At present ESG (Electrostatic Suspended Gyro) is the most precise inertia element in the world. The electrode bowl, which has direct effect on the precision of ESG, is a key part to ESG. Through the analysis of the function and characteristic of the electrode bowl in hollow rotor ESG and the present situation of new material development in the world, the alumina ceramic is regarded as the best material for the electrode bowl of hollow rotor ESG. By analyzing the present situation of alumina ceramic in the world, main technique requirements have been put forward for the alumina ceramic of ESG electrode bowl which is also fit for solid rotor ESG.     

Image segmentation based on competitive learning

lmage segment is a primat.‘y step in image analysis of unexploded ordnance (UXO) detection by ground penetrating radar (GPR) sensor which is accompanied with a lot of noises and other elements that affect the recognition of real target size. In this paper we bring forward a new theory, that is, we look the weight sets as target vector sets which is the new cues in semi-automatic segmentation to form the final image segmentation. The experiment results show that the measure size of target with our method is much smaller than the size with other methods and close to the real size of target.     

一种新的伪并行遗传算法在车间调度中的应用研究

提出了一种改进的伪并行遗传算法(Improved Pseudo-Parallel Genetic A lgorithm,简称IPPGA),将改进遗传算法与SGA伪并行操作(采用并行思想,在同一台机器上完成操作),保证了种群多样性,防止局部早熟收敛;改进算法对部分遗传算子做了改进,采用迭代交叉,多父代产生多子代,让多个染色体中优秀基因段组合产生子代,大大加快收敛速度;设定一个最优个体保存序列库,防止最优解的丢失.采用实际算例进行仿真试验,数据表明改进的伪并行遗传算法(IPPGA)较标准遗传算法(SGA)快速、有效.     

基于结构方程模型的城市共享单车可持续发展条件研究

为规范已运营的共享单车服务,同时为尚未投放共享单车的城市提供决策依据,通过设计和发放李克特调查量表获取受访者对共享单车运营与管理的态度,采用探索性因子分析和验证性因子分析提炼受访者的潜在态度因子,建立表征潜在态度因子之间相关关系、潜在态度因子与调查题项之间相关关系的结构方程模型。模型估计结果表明,通过车辆停放管理和停放技术研发与应用等手段可提升人们规范停放共享单车的意识,而规范共享单车企业的运营行为可改善民众对共享单车的认知,建立共享单车企业品牌效应,提高共享单车企业的市场占有率。     

Factors associated with bicycle ownership and use: a study of six small U.S. cities

As a means of transportation and as a form of physical activity, bicycling generates benefits to the bicyclist as well as to the community as a whole. Bicycling now accounts for less than 1 percent of all trips for all purposes in the U.S., but evidence from other western countries suggests that under the right conditions, bicycling levels can be significantly higher. Indeed, the experiences of some U.S. cities suggest that it is possible to create conditions conducive to higher levels of bicycling even in the U.S. However, the extent to which bicycle investments have contributed to bicycling levels in these communities has not been rigorously assessed. The purpose of this study is to provide a better understanding of the determinants of bicycle ownership and use as a basis for identifying ways to promote bicycling. A cross-sectional study of six cities was designed to test the importance of bicycle infrastructure and other physical environment factors relative to individual factors and social environment factors, using a nested logit model to examine ownership and use decisions jointly. The results show strong effects of individual attitudes and physical and social environment factors on bicycle ownership and use.     

Mass transit systems of Beijing: governance evolution and analysis

Developing a more efficient mass transit system, in highly populated cities, improves the mobility, decreases the dependency of private cars, alleviates traffic congestion, and provides a more environmentally friendly means of travel. Recently, the city of Beijing decided to have a target of becoming as a ‘public-transport city’ with a fascinating mass transit system within a larger plan, of building humanistic, scientific and technological, and green public-transport systems. This work discusses the governance evolution of the mass transit system of Beijing between 1949–2008, comprised of two groups of transit systems, the road surface public-transport system (bus, tram, trolley, etc.), and the subway public-transport system. In addition, a time-series analysis is introduced in an attempt to examine the effect of governance evolution on the two transit systems, and of the impacts of the governance structural changes on the mass transit system. The time-series model is introduced using the annual statistics data of the period 1949–2008. The outcome of the analysis is viewed with precaution because of the incompleteness of the many endogenous and exogenous factors to affect the public-transport demand. Generally speaking it is concluded that the governance evolution provides beneficial effect of the Beijing mass transit activity; however, for satisfying the significant increase of the Beijing city’s travel demand and maintaining sustainable development, the governance-involvement pattern needs to be reformed.