自行车停放管理对策分析

自行车失窃时有发生,停放管理是解决这一问题的有效方法。对不同管理模式的缺陷与适应条件进行了分析,对建设停放设施加强自行车停放安全的手段进行了探讨。结合实际,提出免费自管与收费管理并存的模式。     

新一代半潜船装载仪的开发

本文介绍了一种应用于半潜船的装载仪,性与浮态计算、自由纵倾的稳性与浮态计算等功能。使用单位的一致好评。本装载仪具有甲板货建模、计入甲板货的稳经过多年的使用,本装载仪得到了使用者及     

天津东疆保税港区建设自由贸易港区管理模式探究

为积极探索保税港区向自由贸易港区发展的有效途径,通过借鉴香港、荷兰、迪拜等国家和地区国际自由贸易区发展情况,运用比较方法,分析自由贸易港区发展趋势,对建立适合天津东疆保税港区科学发展的新型管理模式进行有益探讨。     

国际金融危机对广西-东盟物流业的影响及对策

文章基于对东盟的贸易结构、运输方式和广西-东盟的物流业发展现状的分析,以广西物流基础设施发展举措为重点,对国际金融危机下广西-东盟的物流业发展对策进行了探讨。     

整体式钢筋混凝土简支板桥纵向开裂机理浅析

介绍并分析了1孔6（8）m整体式钢筋混凝土简支板桥纵向开裂的受力原因,为以后的设计与施工提供参考。     

Free public transport: A socio-cognitive analysis

In this study, the modal shift potential of introducing a free alternative (free public transportation) and of changing the relative prices of transportation is examined. The influence of a cognitive analysis on the zero-price effect is also analyzed. The data used for the analysis stem from a stated preference survey with a sample of approximately 670 respondents that was conducted in Flanders, Belgium. The data are analyzed using a mixed logit model. The modeling results yield findings that confirm the existence of a zero-price effect in transport, which is in line with the literature. This zero-price effect is increased by the forced cognitive analysis for shopping trips, although not for work/school or recreational trips. The results also demonstrate the importance of the current mode choice in hypothetical mode choices and the importance of car availability. The influence of changing relative prices on the modal shift is found to be insignificant. This might be partially because the price differences were too small to matter. Hence, an increase in public transport use can be facilitated by the introduction of free public transport, particularly when individuals evaluate the different alternatives in a more cognitive manner. These findings should be useful to policy makers evaluating free public transport and considering how best to target and promote relevant policy.     

Comparative measurements on the flow structure of a marine propeller wake between an open free surface and closed surface flows

In order to investigate the effects of a free surface on the wake behind a rotating propeller, experiments were carried out in a circulating water channel for two cases: one with an open free surface and one with a closed free surface covered by a rigid plate. Four hundred instantaneous velocity fields were measured using a two-frame particle image velocimetry (PIV) technique at four different blade phases. These were ensemble-averaged to investigate the time-averaged flow structure in the near-wake region. For a surface ship, the flow behind the propeller is influenced by the hull wake and the free surface. The phase-averaged mean velocity fields show the potential wake and the viscous wake formed by the boundary layers developed on the blade surfaces. The interaction between the bilge vortices and the incoming flow along the ship’s hull deforms the wake structure. Tip vortices are generated periodically, and the slipstream contraction occurs in the near-wake region. The free surface was found to affect the axial velocity component and vortex structure behind the propeller. As the flow goes downstream, the tip and trailing vortices dissipate due to turbulent diffusion and active mixing with adjacent vortices.     

压燃式发动机汽车自由加速法排气烟度(不透光)检验作业指导书

自由加速排气烟度不透光烟度法是检验压燃式发动机汽车排气污染物常用方法之一。本指导书详细阐述了不透光烟度计日常检查方法、不透光烟度法检验步骤以及不透光烟度计校准方法,并提出使用维护方法。     

Numerical modeling of breaking waves generated by a ship’s hull

A new model for the simulation of spilling breaking waves in naval flows is presented. The hydrostatic pressure is used in order to mimic the weight of the breaker on the underlying flow, as in the model of Cointe and Tulin, whereas the algorithm for detecting the breaking inception and the definition of its geometry are completely new and are suitable for the simulation of three–dimensional flows around ships hulls. The model has been implemented in a finite-volume code developed for naval flows, and its performances have been validated against experimental data for a submerged profile, an S60 hull in drift motion, and the US Combatant DTMB 5415 model on a straight course.     

运营高铁精测网复测线上CPⅡ更新判定指标研究

运营高铁精测网复测的核心与难点是线上CPⅡ的稳定性判定与正确更新。在研究分析高铁规范中CPⅡ复测更新指标的基础上,结合多条运营高铁线路复测工程经验,就相邻点间坐标差之差的相对精度易超限的问题,提出新的CPⅡ复测更新判定标准与指标。采用相邻点复测与原测方位角较差分析、CPⅢ自由网平差检核、F检验法,不同方法识别的不稳定点一致,从不同角度论证新的复测更新标准的合理性。理论和实践证明,新的CPⅡ复测更新指标不仅大大减少了点位更新率,且识别出的不稳定点更符合点位实际变动情况,可为相关规范的修订提供参考。