Latent classes of daily mobility patterns: the relationship with attitudes towards modes

Transportation - Active modes (i.e. walking and cycling) have received significant attention by governments worldwide, due to the benefits related to the use of these modes. Consequently,...     

A phenomenological model for dynamic traffic flow in networks

A macroscopic model for dynamic traffic flow is presented. The main goal of the model is the real time simulation of large freeway networks with multiple sources and sinks. First, we introduce the model in its discrete formulation and consider some of its properties. It turns out, that our non-hydrodynamical ansatz for the flows results in a very advantageous behavior of the model. Next the fitting conditions at junctions of a traffic network are discussed. In the following sections we carry out a continuous approximation of our discrete model in order to derive stationary solutions and to consider the stability of the homogeneous one. It turns out, that for certain conditions unstable traffic flow occurs. In a subsequent section, we compare the stability of the discrete model and the corresponding continuous approximation. This confirms in retrospection the close similarities of both model versions. Finally we compare the results of our model with the results of another macroscopic model, that was recently suggested by Kerner and Konhäuser [Phys. Rev. E 48, 2335–2338 (1993)].     

Full-scale fatigue tests of ship structures to validate the S–N approaches for fatigue strength assessment

Ships belong to those welded structures which are prone to fatigue due to high cyclic loads. Different approaches exist for the fatigue strength assessment which are varying between the industrial sectors. Therefore, deeper fatigue strength investigations were performed in Germany within an industry-wide joint research project aiming at the harmonization of the approaches. Regarding ship structures, two types were selected for full-scale tests. The first concerned web frame corners being typical for roll-on/roll-off ships (ro/ro) ships, from which three models were tested under constant amplitude loading. The second type was the intersection between longitudinals and transverse web frames, which recently showed fatigue failures in containerships. Five models were tested, three under constant and two under variable amplitude loading. All tests showed a relatively long crack propagation phase after first cracks had appeared, calling for a reasonable failure criterion. For the numerical analysis, the structural hot-spot stress as well as the effective notch stress approach have been applied. The latter allows the consideration of the weld shape which could partly explain differences in the observed and calculated failure behaviour. Another factor is the distribution of welding-induced residual stresses, which obviously affected the failure behaviour in the web frame corner as well. Insofar the investigations give a good insight into the strength behaviour of complex welded structures and into current problems and opportunities offered by numerical analyses.     

ICE-design and operational aspects

On 2nd June 1991 the high speed rail era in Germany began with the introduction of the ICE (Inter-city express) on the Hamburg-Hannover-Kassel-Frankfurt-Munich line, the second ICE line followed one year later. The ICE concept and the technology of the ICE-train set marks the threshold of the 21st Century and demonstrates the as yet untapped development potential of the wheel-on-rail-system. With the development of the ICE a trainset is available which can be adapted to all European High Speed Rail lines.     

迎风旋转——SSB风能系统公司的创新型变桨系统

对风能的利用是一项非常古老的技术,风磨早在几千年前就为人所用.古巴比伦人就已知道利用风能.然而在过去几十年,这项技术才得到了真正的发展.根据在航空领域所了解的知识,首先推进的是现代风电机的空气动力学技术.变桨系统则是过去30年最重大的成就之一.     

Competing Visions for Marine Tenure and Co-Management: Genesis of a Marine Management Area System in Chile

Chile has been attempting to establish a Management Area (MA) system that melds the use of marine protected areas with marine tenure. The process has brought to the fore the competing interests of various user groups: artisanal fishermen, marine science professionals, government managers, tourist developers, and the Navy. We explore the core relationships among fishermen and the ecologists and biologists whose work is essential for establishing and maintaining a MA. The MA system's creation and implementation raise the key question of whether a marine tenure system can work under the conditions imposed by the Chilean government. There is a need to recognize and reconcile contradictions in a government management model that strives simultaneously to be a conservation zone and a financially profitable co-management zone. This article examines the MA management system's fault lines in the context of Chile's political economy, and the intimate interaction of management with fishermen's cultural survival strategies.     

Data display techniques for transportation analysis and planning: an investigation of three computer‐produced graphics

Graphics are a powerful but often costly means of communication. Computer‐drawn graphics offer a new and relatively inexpensive way to assist the communication of complex technical information to both planners and non‐technical people whose full potential is now beginning to be realized. This paper discusses the utility of graphics and introduces three computer‐drawn graphic techniques which may be useful, both for analysis and presentation of results, in the transportation planning process. CENVUE(S) produces a three‐dimensional, perspective‐view map, on which virtually any type of transportation data or performance indicator can be displayed. VAP is designed to display origin‐destination travel patterns in any region. TDN transforms a physical‐distance network into a time‐distance network so that effects of different speeds in the transportation network can be readily seen. The cost‐effectiveness of each technique is briefly discussed and some recommendations for evaluating computer graphics techniques are provided to aid the user in further assessing their utility in the transportation planning process.