利用全站仪进行曲线放样

介绍GPS测量受限时利用全站仪进行曲线放样的原理、有关公式的推导、计算方法、操作步骤及与GPS测设的精度比较。     

合宁客运专线列控的相关思考

合宁客运专线于2008年4月18日正式开通运营,目前设备运行基本稳定.由于合宁线是我国首条客运专线,其设备构成代表未来我国客运专线的方向.所以有必要对该线采用的列控设备CTCS-2级列控系统进行相关说明.     

关于铁山支线多条专用线接轨后联锁设备方案的选择

铁山支线位于淄博市临淄区金岭镇西部,从胶济线金岭镇站接轨至铁山站,区间线路全长约6.5 km。在该支线周围有大量的厂矿企业,先后有7家企业修专用线。由于多家专用线接轨,     

交通仿真技术在交通事故研究中的应用

交通事故研究对于个人和整个社会都具有重要意义。简述了交通问题的研究方法,并以仿真软件TSIS中的FRESIM模型,分析研究高速公路中的事故黑点对交通特性及环境的影响。另外,通过采用不同的管理措施,进行事故间接经济损失分析。     

A comparative analysis of the European and North-American approaches to dealing with major oil spills

Background  

The question of what should be the right level of preparedness to react to a major oil spill (i.e. the EXXON VALDEZ spill, the ERIKA spill, and the PRESTIGE spill) is highly debated, especially in the aftermath of such spills. Little research, however, has been conducted with the aim to identify and compare governments’ best practices not only to fund preparedness measures but also to assess the countries’ ability to respond effectively to catastrophic oil spills. It is the author’s belief that important lessons can be learnt from a comparative analysis of countries’ best practices.     

我国摩托车燃油蒸发排放国家标准GB 20998-2007的制定与研究(2)

(上接2008年第3期) 实施生产一致性检查试验的关键是生产企业要严格组织生产,控制采购、检验等过程和环节,如果某一车型不满足生产一致性检查要求,应尽快采取有效措施重新建立生产一致性,否则撤销该车型的型式核准.     

Numerical analysis of crack under compression by 3D displacement discontinuity method

A 3D displacement discontinuity method is applied to solve the fracture mechanics problems of the mixed mode crack under compression. Friction between the surface of the closed crack is considered by establishing a simple and efficient iterative algorithm based on method of contact resistance mitigation. On the surfaces of the closed crack, the Mohr-coulomb rule is satisfied by iteration when the crack is in condition of sliding. The stress intensity factors are obtained using displacement fitting method. It is shown that the numerical results agree with the experimental results well and that friction plays an important role in resisting crack propagation.     

Experimental study on the liquid slug of cryogenic slug flow in inclined tubes

An experimental study was carried out to understand the phenomena of the boiling flow of liquid nitrogen in inclined tubes with closed bottom by using a high speed motion analyzer.The experimental tubes are 0.018 and 0.014 m inner diameter(ID) and 1.0 m in length.The range of the inclination angle is 45°-90° from the horizontal.The experimental observation on the liquid slug was carried out along the tubes.Statistical method was employed to analyze the experimental data.The experiment analyzed the influences of the inclination angle and the tube diameter on the liquid slug length and velocity.The results show the liquid slug propagation velocity increases with the decrease of inclination angle θ.For all cases,the maximum values of the mean liquid slug lengths were obtained at θ = 60°.The mean liquid slug lengths were greater for large tube at higher tube position.These conclusions provide a basis for further study liquid slug of cryogenic two-phase undeveloped slug flow.     

“Turn on the radio,bust out a song”: the experience of driving to work

Though driving to and from work has become a prevalent experience in the lives of individuals in every metropolitan region in the US, much remains to be learned about the activity from the perspective of the drivers. To increase our understanding of the motivation for certain travel behaviors, we must first know something about what those drivers experience. The existing literature explains much, but the application of new methodologies could improve our ability to explain the willingness of individuals to choose to drive through increasingly congested road networks. The results of this study of oral histories of 12 women commuters underscore the idea that commute should be seen as a set of subjective behaviors that contradict some existing assumptions about why individuals commute.     

Threshold controlled scheme of difference expansion techniques for reversible watermarking

Since Tian Jun proposed the difference expansion embedding technique, based on which, many reversible watermarking techniques were proposed. However, these methods do not perform well when the payload is high. In this paper, we proposed an expandable difference threshold controlled scheme for these three methods. Experiments show that our scheme improves the performance of these three methods for heavy payload.