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以蜂窝陶瓷为载体,γ-Al_2O_3为活性涂层,制备了负载型钙钛矿催化剂:25%La0.85K0.15CoO_3/Al_2O_3/陶瓷。将催化剂装载于催化器中,基于台架试验研究了该催化器在柴油机尾气净化中的效果。结果表明,该催化器对PM有较好的处理效果,去除率高达98.8%,尾气中NO_x、HC、CO浓度也有较明显的降低,去除率分别为5.22%、27.6%、40.6%,CO_2浓度略有增加。相对于空白催化器,在钙钛矿型催化剂的作用下,PM的催化转化活性大大提高。催化转化温度T50%、T90%分别为365℃、642℃,降低了126℃、143℃,催化转化用时T50%、T90%分别为10 min、42 min,缩短了23 min、43 min。另外,运行过程中发动机压力损失可为催化器再生时机提供选择,无需外加装置与能耗,有利于节约再生成本。 相似文献
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船舶柴油机在燃烧过程中,所吸入的空气中的氮气部分被氧化后,形成各种形式的氮氧化物。柴油机氮氧化物的排放是造成空气污染和影响海洋环境的根源之一。本文详细介绍了73/78船舶柴油机氮氧化物的排放控制技术准则和相关内容。 相似文献
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柴油机的有害排放物是造成大气污染的一个主要来源,通过提高柴油品质,减少润滑的消耗,改善柴油机的燃烧过程和排气后处理等措施,可以大大降低柴油机的有害排放物,达到低排放标准,提高环境质量. 相似文献
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本文选择浙江省沿海典型油气码头、干散货码头、件杂货码头和集装箱专用码头作为监测点,在一个自然年中分别选取代表日进行空气质量监测。根据污染物浓度水平,结合气象条件参数和交通流量参数,对大气污染物进行影响因素分析。结果表明:码头空气质量优于当地整体情况;SO_2、NO_2、PM_(2.5)和PM_(10)浓度变化与气温、湿度、风速呈负相关关系,与气压呈正相关关系,CO浓度受气象条件影响较小;靠港船舶和码头内作业车辆尾气是码头空气污染物的重要来源。 相似文献
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《青海交通科技》2021,(1)
以湖北省五峰土家族自治县某斜交实心板桥为工程背景,考虑混凝土的材料的非线性,分析斜交实心板桥在极限承载状态下的受力状况,同时研究汽车荷载加载过程中结构挠度、应力和裂缝的变化规律。分析结果表明:当汽车荷载达到公路-Ⅱ级的60%时,斜交实心板桥的结构受力进入非线性;当汽车荷载达到公路-Ⅱ级的2. 364倍时斜交实心板桥达到极限承载能力,斜交实心板桥具有足够的安全储备;随着荷载的增大,斜交实心板桥的挠度、应力、裂缝宽度最大值均逐渐增大,且存在较为明显的非线性关系;随着荷载的增大,裂缝的顺桥向分布宽度逐渐增大,横桥向分布走向不完全平行于桥梁端部,稍向斜交板钝角方向偏转。 相似文献
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通过对船用柴油机曲轴轴承损坏原因的分析,从管理、修理角度提出应对措施,拟达到降低事故发生的目的.' 相似文献
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Pedestrians as compared to vehicular traffic enjoy a high degree freedom of movement even in heavily congested areas. Consequently, there are more alternative links available to pedestrians between a given origin‐destination (O‐D) pair. This paper describes a study done by the University of Calgary to evaluate the factors affecting the choice of route on intra‐CBD trips or trips within the Central Business District (CBD). An origin destination survey conducted in downtown Calgary, Alberta enabled the identification of the most significant factors influencing the choice. These factors were analyzed in relation to the physical characteristics of the location, personal characteristics of the trip maker and the type of the trip. It appears that most people chose the shortest link and factors such as the level of congestion, safety or visual attractions were only secondary. This suggests that the length should be made a major consideration when planning and designing pedestrian links. 相似文献
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This paper estimates the efficiencies and productivity changes of 12 international airports in the Asia-Pacific region based on data from 1998 to 2006. We apply stochastic frontier analysis (SFA) to compute efficiency estimates and use the Malmquist productivity index (MPI) to analyze productivity changes. We use the SFA model with a translog-type production function after testing the statistical hypotheses. According to the results of the SFA hypothesis tests, airports have experienced a technological regression; the deviations from the efficiency frontier are caused more by technical inefficiency than random noise. However, the inefficiency was found to decrease. The MPI reveals a declining trend resulting more from technological change than from efficiency change, with a decrease in inefficiency. Taken together, both the hypothesis tests and the MPI not only provide consistent conclusions, but also suggest that airports should concentrate on technological progress. 相似文献
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介绍了城市轨道交通工程中杂散电流不同的监测系统的构成,分析了集中式、分散式和智能型等监测系统的配置和功能,以及智能型实时在线监测系统的重要意义,为轨道交通工程杂散电流监测系统的选择与应用提供参考。 相似文献
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明确埋地管道防腐保温层的技术评价标准,对埋地钢质管道的安全运行,延长管道使用寿命具有重要意义。为了对埋地管道防腐保温层做出有效评价,从间接检测与开挖检测2个方面,结合现场检测数据,提出了基于防腐保温层的电流衰减率、绝缘电阻率、质量状况与厚度的分级评价标准及基于4种评价指标的综合评判方法。工程实践表明,该评价标准对防腐保温层是否存在失效能做出有效判断。 相似文献
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天然气自动计量系统有多种组态软件,由于软件的不相通性,造成了计量系统数据采集的通用性差、数据传输与入库的时效性差、数据利用的可靠性低.结合各组态软件的实际情况,从设计上充分利用Oracle大数据处理能力以及Partition(分区表)的特性,实现历史数据的存储,应用WebService与COM+数据访问组件提供多层数据访问架构,采用OPC与DDE工业数据交换协议,实现了各站场计量数据的实时上传,为连续数据采集和实时监控提供了可能,节约了改造成本. 相似文献
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Joseph N. Prashker 《Transportation》1979,8(4):329-346
Reliability of travel modes was found to be the most important characteristic of transportation systems in several attitudinal investigations of individual travel behavior. This paper represents the first part of a research effort aimed at gaining a better understanding of the characteristics of reliability of transportation modes in urban travel. In this research, reliability characteristics are identified; their importance relative to each other is assessed, and an insight into possible structure of an objective reliability index is discussed. The research is based on perceived values of reliability, which were identified through a large attitudinal survey conducted in the Chicago metropolitan area. 相似文献