长期暴露于紧张刺激(噪声)引起血压升高的一个原因

动物实验早已证明:高度精神紧张是与暂时性血压升高相连系的。若重复暴露于这种紧张刺激——噪声的话,则就会引起永久性的动脉压增高。但是在人类却不是如此明确的表现。本文的主要内容是讨论了长期强噪声暴露的人群是否会引起永久性血压增高的问题。作者通过对196名男性的正常体检。发现74人是属于正常听力(所有测试频率的阈值均小于20分贝)而44人为严重的噪声性听力损失:其阈值在3000,4000或6000赫≥65分贝。其余的78人是属于各种形式的听力损失,不予讨论。而对听力正常者和噪声性听力损失者的血压作了比较,其结果见下表:     

凯特匹勒3406B卡车发动机

新开发的具有新式结构的卡车用3406B强化柴油机是直列六缸机,功率范围为255—400马力(190—298千瓦),相应的额定转速为1600—2100转/分。开发规划的主要目标是继续改善燃油经济性,重点放在改进燃烧室零件和燃油系统,使能满足现在和将来的气体排放和噪音级要求。新的燃油系统是实现这一目标的关键部件之一。本文详述了3409B发动机在设计、研制和性能改进方面的内容。     

燃烧室相对直径对开式燃烧室柴油机性能和缸盖热负荷的影响

本文分析了燃烧室相对直径(d_(cch)/D)与开式燃烧室柴油机诸参数之间的多路相互关系。特别注意在宽口燃烧室条件下获得最高燃烧效率的优化柴油机设计。分析表明,喷油设备的选择对于解决这一问题具有重要作用。文章给出了在不同相对直径d_(cch)/D值时,缸盖热负荷试验研究的结果。作者试图通过充量速度分量的测量来确定热负荷随d_(cch)/D值增大而降低的关系。结果证明不可能单独建立比热通量和温度场与充量运动之间的关系,从而就相应的影响因素提出假定。文章结论中着重提出了浅盆形燃烧室用于高增压柴油机的一些优点以及要解决的某些问题。     

E／L—X型空重车调整装置

介绍ＷＡＢＣＯ公司新研制的Ｅ／Ｌ－Ｘ型货车二级空重车调整阀的结构，作用原理，及其主要性能和试验研究情况。     

苏联船舶结构力学的现况

本文介紹半世紀以来苏联科学家对於船舶結构力学的成就,比較各家的学說,看出其进展情况,如船舶弯矩、撓度、板架的强度及稳定性、上层建筑、許用应力、振动等問題。文首說明船舶結构力学的范圍,文后列举结构力学上存在的主要问题。     

液化气体船舶货舱的惰性化、驱气和清洗特性

本文论述了液化气体船舶在运输以后,对货舱进行修理、检查和更换运输货物时,用真空法和吹风法对货舱进行惰性化、驱气和清洗时的工艺准备工作,并对这两种方法的动力特性、时间特性和惰性气体的消耗量作了比较。     

采用沿岸动力概念以减少埃及红海海域高速船燃料消耗与降低排放(英文)

The progress of economic globalization,the rapid growth of international trade,and the maritime transportation has played an increasingly significant role in the international supply chain.As a result,worldwide seaports have suffered from a central problem,which appears in the form of massive amounts of fuel consumed and exhaust gas fumes emitted from the ships while berthed.Many ports have taken the necessary precautions to overcome this problem,while others still suffer due to the presence of technical and financial constraints.In this paper,the barriers,interconnection standards,rules,regulations,power sources,and economic and environmental analysis related to ships,shore-side power were studied in efforts to find a solution to overcome his problem.As a case study,this paper investigates the practicability,costs and benefits of switching from onboard ship auxiliary engines to shore-side power connection for high-speed crafts called Alkahera while berthed at the port of Safaga,Egypt.The results provide the national electricity grid concept as the best economical selection with 49.03 percent of annual cost saving.Moreover,environmentally,it could achieve an annual reduction in exhaust gas emissions of CO2,CO,NOx,P.M,and SO2by 276,2.32,18.87,0.825 and 3.84 tons,respectively.     

大型基础设施系统设计中的风险及概率

在大型基础设施系统中,不可避免地会出现重大的不确定性,因而,无法确保已建系统的安全性和可靠性.有功能失效甚至破坏的可能,同时也有相应的规避风险的措施.从实用角度出发,不确定性可以分为两大类:数据型(又称偶然型)不确定性和知识型(又称认知型)不确定性.前者可以通过对数据的观察来评估,而后者则需要主观判断.系统地分析了这两...     

船舶SOFC燃料电池与汽轮机联合动力装置能效分析(英文)

Strong restrictions on emissions from marine power plants(particularly SOx,NOx)will probably be adopted in the near future.In this paper,a combined solid oxide fuel cell(SOFC)and steam turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector.The analyzed variant of the combined cycle includes a SOFC operated with natural gas fuel and a steam turbine with a single-pressure waste heat boiler.The calculations were performed for two types of tubular and planar SOFCs,each with an output power of 18 MW.This paper includes a detailed energy analysis of the combined system.Mass and energy balances are performed not only for the whole plant but also for each component in order to evaluate the thermal efficiency of the combined cycle.In addition,the effects of using natural gas as a fuel on the fuel cell voltage and performance are investigated.It has been found that a high overall efficiency approaching 60%may be achieved with an optimum configuration using the SOFC system.The hybrid system would also reduce emissions,fuel consumption,and improve the total system efficiency.     

电竞未来

不仅是保时捷创新突破、向传统致敬的手段。更是对超跑一词重新定义的划时代钜作。