车身产品开发中逆向设计的研究与应用

逆向设计是现代汽车产品快速开发的重要技术。本文介绍了汽车车身产品开发流程及逆向设计关键技术和应用软件,从点云数据采集、曲面重构、曲面数据质量评估等方面分析了逆向设计在汽车车身产品开发中的应用情况。     

船舶防爆电气设备应用中应注意的问题

分析了防爆电气设备在选型中存在的若干问题,提出了在设计中选择防爆电气设备的步骤,并对其安装、验收加以一一说明。     

北京市政公交一卡通使用现状及改进策略研究

本文分析了北京市政公交一卡通使用过程中的优越性和存在的问题;介绍了上海、香港使用一卡通的成功之处;结合北京市的市情和交通现状,针对北京市公交一卡通存在的问题,提出了培养市民刷卡文化、完善管理制度、强化售后服务、优化公交站台和线路设置、实现一卡互通、异地互联互通等建议.     

车辆电磁制动方案刍议

结合机车车辆制动系统的运行情况,对电磁制动系统进行了初步探讨.提出了两种电磁制动方案:单电磁铁失电制动和双电磁铁得电制动.方案能够初步解决电磁制动系统中的一些技术难点,如减轻闸瓦间隙消除过程中闸瓦与车轮间的机械碰撞、电磁力的计算与控制、制动力的放大与传递等.     

农用车辆配套简易播种机设计

文章介绍的旋耕播种机主要由六个部分组成,即:悬挂装置、动力传输装置、旋耕装置、播种装置、镇压装置和链条传动装置。农用车辆拖拉机前进后镇压装置也向前运行带动链条传动装置,与之另一端连接的播种箱的播种轴也随之转动,使种子从排种孔中流出顺着播种管与播种开沟器流出最后流入垄沟,从而实现播种机的播种作业。播种机播种后的农作物生长均匀分布排列整齐,这样可以便于人们实现播种过后对田地的管理作业,也是人们实现农业机械现代化的重要技术手段之一。     

武汉光谷国际网球中心与三环线衔接匝道研究

介绍了武汉市三环线武黄立交新增匝道的设计思路、方案调整及匝道车道数研究。通过分析新增匝道建设的主要受控因素,提出了三环线到达及驶离网球中心停车场不同路径的匝道方案,并从多方面对匝道方案进行综合比选。     

强迫布鲁塞尔振子相图的研究

针对强迫布鲁塞尔振子模型的Ｆａｒｅｙ序列与Ｍ．Ｓ．Ｓ序列进行了扩大区域的研究，表明单峰映中看成圆映象的近似，并建立了圆映象的相图，单峰映象的相图及符号动力学间的关系。     

Timing sequence changes of landscape plants in Shanghai Area,China

Based on published reports and direct observation, the common resources of landscape plant species in the Shanghai area were identified and studied in terms of the landscape characteristics of timing sequence changes over a one year time period. The results showed that there were 199 common landscape plant species in Shanghai, distributed in 67 families and 129 genera. These plants were categorized by three ornamental characteristics: flowers, foliage and fruits. The species were thus further analyzed according to the time periods which these characteristics were present. The results showed that flower ornamental distributed throughout the year, particularly from April to June, and plant species with colorful foliage could be seen every month, and particularly in November and December. On the other hand, few plant species with fruit ornamentals were observed in Shanghai area. The diversity of landscape timing sequence changes of the 199 plant species under examination was then analyzed by using the Shannon-Weiner and Simpson index formulas. The results showed that the higher diversity was observed in January, February and from August to October, while the lowest diversity was recorded from March to July and during November and December. The diversity of landscape characteristics of these plants was ranked according to foliage, flowers and fruit. Using this method, one park and one plant community were selected to evaluate the advantages and disadvantages of their time-changing plant landscape, with the goal of assessing the validity of the chosen ranking method. These results in the present study would be helpful to evaluate the plant landscape in a specified space and further enrich the diversity of plant and landscape by a target-oriented way.     

A mixed Bayesian network for two-dimensional decision modeling of departure time and mode choice

The modeling of travel decision making has been a popular topic in transportation planning. Previous studies focused on random-utility discrete choice models and machine learning methods. This paper proposes a new modeling approach that utilizes a mixed Bayesian network (BN) for travel decision inference. The authors use a predetermined BN structure and calculate priori and posterior probability distributions of the decision alternatives based on the observed explanatory variables. As a “utility-free” decision inference method, the BN model releases the linear structure in the utility function but assumes the traffic level of service variables follow multivariate Gaussian distribution conditional on the choice variable. A real-world case study is conducted by using the regional travel survey data for a two-dimensional decision modeling of both departure time choice and travel mode choice. The results indicate that a two-dimensional mixed BN provides better accuracy than decision tree models and nested logit models. In addition, one can derive continuous elasticity with respect to each continuous explanatory variable for sensitivity analysis. This new approach addresses a research gap in probabilistic travel decision making modeling as well as two-dimensional travel decision modeling.     

日本造船业的危机应对

接单策略偏于谨慎 2008年初时,日本各大船厂手持订单饱满,生产任务普遍排至2011年左右,而造船钢材价格却是一涨再涨,使得本来可以获利的订单转眼间变成赔本的生意,船厂的财务业绩因钢材上涨而面临巨大压力,接单越多可能最后亏损越多.