The impact of climate change and weather on transport: An overview of empirical findings

This paper presents a survey of the empirical literature on the effects of climate change and weather conditions on the transport sector. Despite mixed evidence on many issues, several patterns can be observed. On a global scale especially shifts in tourism and agricultural production due to increased temperatures may lead to shifts in passenger and freight transport. The predicted rise in sea levels and the associated increase in frequency and intensity of storm surges and flooding incidences may furthermore be some of the most worrying consequences of climate change, especially for coastal areas. Climate change related shifts in weather patterns might also cause infrastructure disruptions. Clear patterns are that precipitation affects road safety by increasing accident frequency but decreasing severity. Precipitation also increases congestion, especially during peak hours. Furthermore, an increased frequency of low water levels may considerably increase costs of inland waterway transport. Despite these insights, the net impact of climate change on generalised costs of the various transport modes are uncertain and ambiguous, with a possible exception for inland waterway transport.     

Quantifying erosion rates and stability of bottom sediments at mussel aquaculture sites in Prince Edward Island,Canada

Downward fluxes of organic biodeposits under suspended mussel culture cause benthic impacts such as microbial mat production. Quantifying sediment erosion in these coastal ecosystems is important for understanding how fluxes of organic matter and particulates contribute to benthic–pelagic coupling. Critical shear velocity (u?), erosion rates and particle size distributions of resuspended sediment were measured at two sites; an impacted muddy site with extensive mussel culture (site 1), and a coarser sandier site with less mussel influence (site 2), using a new method for assessing sediment erosion at Tracadie Bay, Prince Edward Island in August 2003. Shear forces were generated by vertically oscillating a perforated disc at controlled frequencies. These forces correspond to shear velocity, using a re-designed and calibrated Particle Erosion Simulator. Undisturbed sediment cores obtained by divers and grab (sub-cored using a Plexiglas? cores) were exposed to shear stress to compare differences between collection methods. Microbial mats were present at site 1 which initially biostabilized sediment against erosion due to ‘armoring’ of the sediment, but onset of erosion was abrupt once these mats failed. Erosion sequences at site 2 (without mat cover) were smoother resulting in less material being eroded. Mean mass of material eroded was 47 and 23 g m^? 2 min^? 1 at sites 1 and 2 respectively. Mat area cover and shear velocity was strongly related. Critical shear velocities varied between 1.70 and 1.77 cm s^? 1, with no obvious differences between location or collection method, so sediments from these two contrasting sites had identical mean critical shear velocities. Significant differences existed in the concentrations of chlorophyll a, colloidal and bulk carbohydrates, between mats and bare sediment from site 1. Particle sizes measured by videography of resuspended sediment at different shear velocities ranged from 100 μm (the minimum diameter capable of being detected by the system), to large mat fragments of 1700 μm for both sites. These results provide evidence of the relevance of using a portable erosion device to indicate how sediment erodability is affected by mussel–microbial relationships.     

关于发布铁路工程建设2007年度辅助材料价差系数的通知

各铁路局、集装箱、投资公司，各铁路公司（筹备组）： 现发布铁路工程建设2007年度辅助材料价差系数（见附件），作为以铁道部《铁路基本建设工程设计概（预）算编制办法》（铁建设[2006]113号，以下简称“113号文”）、《铁路工程建设材料基期价格（2005年度）》（铁建设[2006]129号，以下简称“129号文”）为依据编制工程设计概（预）算时，将辅助材料价格由基期年（2005年）调整到编制年（2007年）的依据。     

电气化动力总成——它会带来什么?

<正>德尔福公司与上海汽车集团股份有限公司("上海汽车")达成协议,将为上海汽车开发的中度混合动力车提供混合动力技术。这一协议的签署具有开创性的重要意义,它将目前中国市场最大的整车制造商上海汽车与德尔福公司的     

Comparative analysis of vehicle brake data in the ministry of transport test on the roller brake tester and on flat ground

This study performs a comparison between what occurs when braking on a Ministry of Transport (MOT) brake tester and on flat ground. The tire pressure is changed, but the other parameters remain constant. The results from this research and from the in-depth comparative study conducted by the mechanical engineering staff in the mechanical laboratory at the Miguel Hernández University in Elche have led to the following main conclusions: By varying the tire pressure, false results can be obtained with the MOT brake tester, which means that, if the tires are inflated at a low pressure but the brakes are in good condition, the vehicle will not pass the MOT. Conversely, if the brakes are in poor condition but the tire pressure is higher than what is recommended by the manufacturer, a false pass is produced. This article shows that the MOT brake testing equipment is often wrong and inexact, and the data and graphs presented prove that the tire pressure is a determining factor when assessing the condition of brakes.     

A study of vibration and vibration control of ship structures

This paper examines the vibration characteristics and vibration control of complex ship structures. It is shown that input mobilities of a ship structure at engine supports, due to out-of-plane force or bending moment excitations, are governed by the flexural stiffness of the engine supports. The frequency averaged input mobilities of the ship structure, due to such excitations, can be represented by those of the corresponding infinite beam. The torsional moment input mobility at the engine support can be estimated from the torsional response of the engine bed section under direct excitation. It is found that the inclusion of ship hull and deck plates in the ship structure model has little effect on the frequency-averaged response of the ship structure. This study also shows that vibration propagation in complex ship structures at low frequencies can be attenuated by imposing irregularities to the ring frame locations in ships. Vibration responses of ship structures due to machinery excitations at higher frequencies can be controlled by structural modifications of the local supporting structures such as engine beds in ships.     

机车轴悬式电机悬挂齿轮副变形的三维有限元分析

本文用三维有限元方法对东风_4型内燃机车的整个牵引电机传动系统进行了计算。其计算模型利用假想的二力杆连接齿轮副的啮合点,人为地造成了均匀传递啮合力的力学条件,从而计算出了合理的齿轮修形量。