Changing patterns of urban travel Part 2. public transport and future patterns of travel

This two‐part paper contains most of a report prepared by TRRL for the European Conference of Ministers of Transport, and presented by one of the authors to the Council of Ministers in November 1984. Part 1, which was published in the January‐March 1986 issue of Transport Reviews, looked at the way cities have been changing over the years and the influence of growing car ownership on trip patterns. This part examines the changes in public transport use in more detail, considers the interactions between the various underlying trends, speculates on future travel patterns by both public and private means and considers the likely impact of land use and transport policies.     

自我反省 SARAH BRAMAN的深秋暖日展

这是一个严肃的命题。作为艺术界的"饱学之士",龚福尔现代艺术中心(Confort Moderne)将通过SarahBraman的雕塑传达一种"针对近期某些愤世嫉俗的知识分子言论以及带有自我反省色彩的玄妙语言而作出的救赎性反应"。我可以向你保证,有许多理由足以促使你去普瓦捷(Poitiers)参观这位美国艺术家的展览!首先,你可以看到各种     

Green-Naghdi theory, part A: Green-Naghdi (GN) equations for shallow water waves

In this work,Green-Naghdi (GN) equations with general weight functions were derived in a simple way. A wave-absorbing beach was also considered in the general GN equations. A numerical solution for a level higher than 4 was not feasible in the past with the original GN equations. The GN equations for shallow water waves were simplified here, which make the application of high level (higher than 4) equations feasible. The linear dispersion relationships of the first seven levels were presented. The accuracy of dispersion relationships increased as the level increased. Level 7 GN equations are capable of simulating waves out to wave number times depth . Numerical simulation of nonlinear water waves was performed by use of Level 5 and 7 GN equations, which will be presented in the next paper.     

集束塔式立管总体强度分析(英文)

Bundled hybrid offset riser (BHOR) global strength analysis, which is more complex than single line offset riser global strength analysis, was carried out in this paper. At first, the equivalent theory is used to deal with BHOR, and then its global strength in manifold cases was analyzed, along with the use of a three-dimensional nonlinear time domain finite element program. So the max bending stress, max circumferential stress, and max axial stress in the BHOR bundle main section (BMS) were obtained, and the values of these three stresses in each riser were obtained through the "stress distribution method". Finally, the Max Von Mises stress in each riser was given and a check was made whether or not they met the demand. This paper provides a reference for strength analysis of the bundled hybrid offset riser and some other bundled pipelines.     

系统识别法在双自由度涡激振动试验研究中应用(英文)

采用系统识别的方法对双自由度圆柱体的涡激振动特性进行了分析研究.试验是在美国麻省理工大学开展,在得到的圆柱体涡激振动轨迹中,由于受到试验条件的影响,如自由液面和水池池底,得到的轨迹并非对称的"8字形".因此首先对原始试验结果进行了分解,得到其傅里叶级数展开形式,然后采用了系统识别的方法对其进行分解,分别得到对称和非对称的试验结果,并认为对称的结果为理想或深海条件下圆柱体的涡激振动轨迹,而在自由液面和水池池底等其他因数的干扰下,产生了非对称的试验结果.     

The drag on an airplane taking off from a floating runway

The motions of an infinitely long, two-dimensional runway subjected to the dynamic moving load imposed by an airplane taking off are investigated. The runway is assumed to be floating in an inviscid fluid and is initially at equilibrium before the plane takes off. The deformation of the runway resulting from the take-off is wave-like and moves in the same direction as the plane. The maximum drag occurs when the plane catches up with the first wave. Three different runway configurations were considered: a baseline and ones which were ten and one hundred times more flexible than the baseline. For these runways, the added drag to the aircraft was very small, ranging from 1% for the stiffest to 10% for the most flexible runway.     

An experimental testbed for mobile offshore base control concepts

 The concept of a mobile offshore base (MOB) reflects the need to stage and support military and humanitarian operations anywhere in the world. A MOB is a self-propelled, modular, floating platform that can be assembled into lengths of up to 2 km, as required, to provide logistic support to US military operations where fixed bases are not available or adequate. It accommodates the take-off and landing of C17 aircraft, and can be used for storage, as well as to send resources quickly to shore. In most concepts, the structure is made of three to five modules, which have to perform long-term station-keeping in the presence of winds, waves, and currents. This is usually referred to as dynamic positioning (DP). In the MOB, the alignment is maintained through the use of thrusters, connectors, or a combination of both. In this paper, we consider the real-time control of scaled models of a MOB. The modules are built at the 1 : 150 scale, and are kept aligned by rotating thrusters under a hierarchical hybrid control scheme. This paper describes a physical testbed developed at the University of California, Berkeley, under a grant from the US Office of Naval Research, for the purpose of evaluating competing MOB control concepts. Received: June 4, 2002 / Accepted: October 30, 2002 Acknowledgments. This material is based on work supported by the MOB Program of the US Office of Naval Research under grant N00014-98-1-0744. The authors would like to thank the Link Foundation for its support. Many thanks go to Stephen Spry for his experimental work. The photographs are courtesy of Bill Stone, Gerald Stone, and Jay Sullivan of the PATH Publications staff. Address correspondence to: A.R. Girard (e-mail: anouck@eecs.berkeley.edu)     

当车遇上X射线

"谁会在里面呢?"15年来,每当尼克维阿瑟对人体或者实物进行X线照相时,这个"亘古不变"的问题都会浮现在他的脑海里。令人不解的是,这个对X光射线近乎痴狂的英国人,既不是医生,也不是科学家。人们不禁要问,究竟是什么在他的体内激发出了如此冷门的关趣?事实上,尼克在16岁时就早早辍学,之后为了生计,也只是做了几份     

当车遇上X射线

"谁会在里面呢?"15年来,每当尼克维阿瑟对人体或者实物进行X线照相时,这个"亘古不变"的问题都会浮现在他的脑海里。令人不解的是,这个对X光射线近乎痴狂的英国人,既不是医生,也不是科学家。人们不禁要问,究竟是什么在他的体内激发出了如此冷门的关趣?事实上,尼克在16岁时就早早辍学,之后为了生计,也只是做了几份无关痛痒的兼职。也就在那时候,他买了自己的第一个相机,正式开始自己的职业生涯。他起初也只是接一些小打小闹的活。虽然做起来很酷,但是收入也很有限。直到他33岁那年,他才终于找到属于自己的"地盘":X射线。直到现在,尼克仍会把当时看做自己的"命运时刻"。     

Quantifying copepod kinematics in a laboratory turbulence apparatus

We describe application of a new apparatus that permits simultaneous detailed observations of plankton behavior and turbulent velocities. We are able to acquire 3D trajectories amenable to statistical analyses for comparisons of copepod responses to well-quantified turbulence intensities that match those found in the coastal ocean environment. The turbulence characteristics consist of nearly isotropic and homogeneous velocity fluctuation statistics in the observation region. In the apparatus, three species of copepods, Acartia hudsonica, Temora longicornis, and Calanus finmarchicus were exposed separately to stagnant water plus four sequentially increasing levels of turbulence intensity. Copepod kinematics were quantified via several measures, including transport speed, motility number, net-to-gross displacement ratio, number of escape events, and number of animals phototactically aggregating per minute. The results suggest that these copepods could control their position and movements at low turbulence intensity. At higher turbulence intensity, the copepods movement was dominated by the water motion, although species-specific modifications due to size and swimming mode of the copepod influenced the results. Several trends support a dome-shaped variation of copepod kinematics with increasing turbulence. These species-specific trends and threshold quantities provide a data set for future comparative analyses of copepod responses to turbulence of varying duration as well as intensity.