The effect of the inflation pressure of tyres on motorcycle weave stability: experiments and simulation

Increasing the stability of a motorcycle requires an understanding of the optimal conditions of the tyre. The inflation pressure is one of the main parameters that directly affects the tyre properties, which in turn influences motorcycle stability and safety. This paper focuses on the effect of the inflation pressure of the tested tyres on motorcycle weave stability. Experimental data are collected from tests carried out in straight running at constant speed. The data analysis is based on stochastic subspace identification methods. Simulations are performed using an advanced motorcycle multi-body code with parameters measured from the tested vehicle. Finally, the comparison between simulations and experimental tests is discussed. The research results show an agreement between experimental tests and simulations where weave stability increases with inflation pressure for the specified range of tyre pressure.     

韩国HSR 350x型高速动车组的开发

韩国在引进法国TGV之后于2004年4月1日启动了韩国特快列车(KTX)的运营,从此韩国便开始步入了高速铁路时代,这被称为"内陆运输革命".此外,韩国通过名为"高速铁路技术开发"的国家研发项目,自主研制出350型高速试验动车组(HSR 350x),在2003年9月汉城至釜山高速试验线上运行时,其运行速度超过了300 km/h.HSR 350x作为最佳技术成果载入韩国铁路史.HSR 350x是韩国工程技术人员研制的,从概念设计到在线试验共用了6年的时间.按既定目标该动车组投入Honam高速线的商业运营以及在先期的运行中确定其与地面设施的兼容性.这样,韩国能充分利用自己的技术设计高速铁路、开发主要设备和生产动车组.也就是说,韩国通过修建汉城至釜山的高速铁路线,能进一步掌握高速铁路的建造、管理与维护技术.这一巨大成果将使韩国成为世界上拥有最佳高速铁路技术水平的国家之一.详细介绍了HSR 350x型高速动车组及其主要核心设备的开发.     

Primary productivity of the Palmer Long Term Ecological Research Area and the Southern Ocean

A major objective of the Palmer Long Term Ecological Research (Palmer LTER) project is to obtain a comprehensive understanding of the various components of the Antarctic marine ecosystem. Phytoplankton production plays a key role in this so-called high nutrient, low chlorophyll environment, and factors that regulate production include those that control cell growth (light, temperature, and nutrients) and those that control cell accumulation rate and hence population growth (water column stability, grazing, and sinking). Sea ice mediates several of these factors and frequently conditions the water column for a spring bloom which is characterized by a pulse of production restricted in both time and space. This study models the spatial and temporal variability of primary production within the Palmer LTER area west of the Antarctic Peninsula and discusses this production in the context of historical data for the Southern Ocean. Primary production for the Southern Ocean and the Palmer LTER area have been computed using both light-pigment production models [Smith, R.C., Bidigare, R.R., Prézelin, B.B., Baker, K.S., Brooks, J.M., 1987. Optical characterization of primary productivity across a coastal front. Mar. Biol. (96), 575–591; Bidigare, R.R., Smith, R.C., Baker, K.S., Marra, J., 1987. Oceanic primary production estimates from measurements of spectral irradiance and pigment concentrations. Global Biogeochem. Cycles (1), 171–186; Morel, A., Berthon, J.F., 1989. Surface pigments, algal biomass profiles and potential production of the euphotic layer—relationships reinvestigated in view of remote-sensing applications. Limnol. Oceanogr. (34), 1545–1562] and an ice edge production model [Nelson, D.M., Smith, W.O., 1986. Phytoplankton bloom dynamics of the western Ross Sea ice edge: II. Mesoscale cycling of nitrogen and silicon. Deep-Sea Res. (33), 1389–1412; Wilson, D.L., Smith, W.O., Nelson, D.M., 1986. Phytoplankton bloom dynamics of the Western Ross Sea ice edge: I. primary productivity and species-specific production. Deep-Sea Res., 33, 1375–1387; Smith, W.O., Nelson, D.M., 1986. Importance of ice edge phytoplankton production in the Southern Ocean. BioScience (36), 251–257]. Chlorophyll concentrations, total photosynthetically available radiation (PAR) and sea ice concentrations were derived from satellite data. These same parameters, in addition to hydrodynamic conditions, have also been determined from shipboard and Palmer Station observations during the LTER program. Model results are compared, sensitivity studies evaluated, and productivity of the Palmer LTER region is discussed in terms of its space time distribution, seasonal and interannual variability, and overall contribution to the marine ecology of the Southern Ocean.     

The Competitive dynamics of the freight container manufacturing industry

This article investigates the on-going relocation of freight container production, particularly in the standard dry freight segment, from South Korea and Taiwan to emerging economies (especially China and south-east Asia). It offers an assessment of their competitive positions but goes beyond the conventional focus on comparative cost advantage among nations. Drawing on the wealth of trade, investment, location and strategic management theories, it explores other variables including demand condition, industry structure, foreign direct investments and vertical industry linkages, besides production factor cost.     

U.S. public transit earnings, employment and privatization

This paper uses individual worker and municipal information to examine privatization's influence on public transit workers' earnings and employment. OLS findings on labor earnings reveal that privatization is associated with an erosion of the public transit union premium. These labor earning findings do not change when correcting for privatization heterogeneity, as unobserved worker characteristics do not differ with differing levels of municipal privatization of public transit services. The employment findings reveal that union public transit workers are more likely to be employed in the public sector and this union-nonunion employment probability differential, declines with increasing levels of privatization. This employment result is interpreted as suggesting that labor cost savings from privatization can be derived from the enhanced employment of relatively low wage nonunion workers in the public sector of public transit services.     

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.     

The 50<Superscript>th</Superscript> anniversary of container shipping the Admiral Sheldon Kinney (USN) lectures

The paper offers a historical overview of the container revolution. It starts from the origin more than 50 years ago, presenting how the pioneer Malcom McLean came to this idea that has changed the nature of Shipping. It then presents how and why container shipping was gradually accepted and what has been the main trends during the last 50 years: the increase in vessels’ and containers’ size and in vessels’ speed. Finally, the paper investigates what the future will bring and notably sheds light on the increase in containers’ size and on the improvements in terminal and rail services.     

感应电动机低速运行时带磁通补偿的直接转矩控制

直接转矩控制的感应电动机的速度控制需要有效地建立定子磁通.但当电动机运行在低速区时就很困难,因为定子电阻上的压降与输入定子电压近似,不可忽略.由此,提出了一种简单而有效的方法来补偿定子电阻上的压降,从而构建定子磁通时无需像大多数专家那样需要确定定子电阻.这样就通过有效的定子磁通补偿建立了电动机转矩,使得直接转矩控制在感应电动机的低速区也同样适用.     

A traffic flow simulator for network reliability assessment

This paper investigates the transportation network reliability based on the information provided by detectors installed on some links. A traffic flow simulator (TFS) model is formulated for assessing the network reliability (in terms of travel time reliability), in which the variation of perceived travel time error and the fluctuations of origin-destination (OD) demand are explicitly considered. On the basis of prior OD demand and partial updated detector data, the TFS can estimate the link flows for the whole network together with link/path travel times, and their variance and covariance. The travel time reliability by OD pair can also be assessed and the OD matrix can be updated simultaneously. A Monte Carlo based algorithm is developed to solve the TFS model. The application of the proposed TFS model is illustrated by a numerical example.     

Fuzzy expert system for controlling swamp terrain intelligent air-cushion tracked vehicle

A fuzzy expert system was used in this study to control an intelligent air-cushion tracked vehicle (IACTV) as it operated in a swamp peat terrain. The system was effective in controlling the intelligent air-cushion vehicle while measuring the vehicle traction (TE), motion resistance (MR), power consumption (PC), cushion clearance height (CCH) and cushion pressure (CP). An ultrasonic displacement sensor, pull-in solenoid electromagnetic switch, pressure-control sensor, microcontroller, and battery pH sensor were incorporated into the fuzzy expert system (FES) to experimentally determine the TE, MR, PC, CCH, and CP. In this study, we provide an illustration of how an FES might play an important role in the prediction of the power consumption of the vehicle’s intelligent air-cushion system. The mean relative error in the actual and predicted values from the FES model with respect to tractive effort, total motion resistance and total power consumption were found to be 5.58 %, 6.78 % and 10.63 %, respectively. For all parameters, the relative error in the predicted values was found to be less than the acceptable limit (10%), except for the total power consumption. Furthermore, the goodness of fit of the predicted values was found to be close to 1.0 as expected and, hence, indicates the good performance of the developed system.