解析接触网高速受流动态特性之间的关联

通过弓网之间作用的波动方程,借助波的传播理论,对波的速度特性、质量特性所影响高速运行条件下的弓网受流特性进行解析,找出其对弓网动态接触压力、接触线的抬升量、接触导线应力等重要指标的潜在影响因素,剖析其内在的、关联的复杂机理,最终归咎于对速度、导线张力、受电弓抬升力等可控值的设计理念上。解析了接触网系统自身震荡的频率特性和弓网间发生谐振现象的机理。最后提供了在我国已成功实施的两个高速接触网系统及其部分动态特性参数。     

匹罗卡品家兔点眼对葡萄膜巩膜途径房水流出量的影响

为探讨匹罗卡品家兔点眼对葡萄膜巩膜途径房水流出色的影响，用1％匹罗卡品（Pilocarpine，PC）对家免单侧点眼。并用0.1mmol／L异硫氰酸荧光素牛血清白蛋白（Fluoreceinisothlocyanate－bovineserumalbumin，FITC－BSA）持续前房灌注30min。测定前、后葡萄膜等6种组织的FITC－BSA含量，计算每眼的葡萄膜巩膜层水流出量（Uveosderdoutflow，Fu）。分别比较点眼前后眼压和点眼后双眼的Fu。结果示：PC点眼后1h处理眼眼压为（0．70±0．08）kPa，下降率为25％（P＜0．01），对照眼眼压无显著变化（P＞0．05）；点眼后2h处理眼Fu值为（0．123±0．026）μl／min，对照眼Fu值为0．177±0．032）μl／min，双眼比较差异有显著性（P＜0．05）。说明1％PC单侧点眼可降低正常家兔眼压，PC可阻断家兔葡萄膜巩膜途径房水外流，兔眼的眼压下降主要为前路排出增加所致。     

制动夹钳用支持架加工工艺

介绍了动车组制动夹钳用支持架的制造工艺,分析了原加工工艺,对存在的质量问题提出了改进意见。改进后的工艺满足产品质量要求。     

The commercialization of East European liner shipping: the experience of Poland

This paper will examine the impact of continuous and increasing change in the shipping sector of Eastern Europe with particular reference to the liner sector in Poland one of the more dynamic markets that has emerged since the political, economic and social changes of the late 1980s. Polish Ocean Lines, and in particular POL Levant, a relatively new, commercialized subsidiary operating in the private sector, are taken as case studies to assess the new structures that are emerging in the marketplace.     

Role of filtering and biodeposition by Adamussium colbecki in circulation of organic matter in Terra Nova Bay (Ross Sea, Antarctica)

At Terra Nova Bay, the scallop Adamussium colbecki (Smith, 1902) characterises the soft and hard bottoms from 20 to 80 m depth, constituting large beds and reaching high values of density (50–60 individuals/m²) and biomass (120 g/m² DW soft tissues). To assess its role in the organic matter recycling in the coastal ecosystem, its filtering and biodeposition rates were evaluated in laboratory experiments during the austral summer 1993/94. Filtration rates, measured in a flow-through system, were calculated from the difference in particulate organic carbon (POC), nitrogen (PON) and chlorophyll-a (Chl-a) concentration in inflow and outflow water. Experiments were performed using natural sea water with POC, PON and Chl-a concentrations of about 450 μg/l, 90 μg/l and 2 μg/l, respectively. The biodeposition rate and the biochemical composition of the biodeposits were studied in order to detect how the organic matter is transformed through feeding activity of A. colbecki. At +1°C temperature, the average filtering rate was about 1 l h⁻¹ g⁻¹ (DW soft tissues) in specimens ranging in body mass from 2 to 3 g (DW soft tissues) and 6–7 cm long. The biodeposition rate in 3–8 cm long specimens, ranging from 0.4 to 5.7 g (DW soft tissues), was about 5.65 mg DW/g DW/day, leading to an estimate of Corg flux, through biodeposition by A. colbecki, of about 21 mg C m⁻² day⁻¹ at in situ conditions. Comparison between the biochemical composition of seston and biodeposits shows a decrease of the labile compounds, of the Chl-a/phaeopigments ratio in the biodeposits. The recorded C/N ratio decrease suggests a microbial colonisation in the biodeposits. This study suggests that Adamussium colbecki plays an important role in coupling the material fluxes from the water column to the sea bed, processing about 14% of total Carbon flux from the water column to the sediments, with an assimilation efficiency of 36%.     

可控停车器的微机控制

作者介绍了可控停车器的几种控制模式及计算机控制技术在停车器控制中的应用,研究提出了系统的体系结构和软件处理流程。     

编者的话

今年一季度，在全球经济不景气等因素影响下，占汽车总销量30％左右的商用车市场继续低迷。目前这一市场受政策刺激较慢，受经济波动影响仍明显，形势不容乐观。1～3月商用车产销6926万辆和68．31万辆，同比下降438％和6．13％。