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应用AIM/Local中国模型定量分析减排技术协同效应对气候变化政策的影响 被引量:11
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作者 杨宏伟 《能源环境保护》 2004年第2期1-4,共4页
IPCC评价报告全面分析了温室气体减排政策措施所产生的对改善当地环境的协同效应 ,但目前国际上对国内环境保护政策措施所产生的减少温室气体排放的协同效应的研究还很缺乏 ,而后者更符合广大发展中国家的实际情况。应用区域能源环境经... IPCC评价报告全面分析了温室气体减排政策措施所产生的对改善当地环境的协同效应 ,但目前国际上对国内环境保护政策措施所产生的减少温室气体排放的协同效应的研究还很缺乏 ,而后者更符合广大发展中国家的实际情况。应用区域能源环境经济综合评价模型 ,考虑现行技术及未来技术发展、当地环境保护政策和未来经济发展等因素 ,并结合对北京市的案例研究 ,来定量分析减排技术的这两种协同效应对我国气候变化政策的影响 。 展开更多
关键词 协同效应 中国 量分析技术 AIM/Local 环境保护 温室气体
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影响抽油泵有效功率的因素分析与建议 被引量:6
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作者 姜晓刚 段敬黎 +2 位作者 贾彦杰 庞然 马续强 《石油机械》 北大核心 2011年第8期69-73,共5页
提高抽油泵的实际排量是提高抽油泵有效功率的关键因素。从抽油泵漏失量、阀球启闭造成的排量损失、泵腔未充满造成的排量损失及抽油杆、油管弹性变形对抽油泵排量影响等方面,分析了影响抽油泵排量的因素,并对每一种因素提出了相应的改... 提高抽油泵的实际排量是提高抽油泵有效功率的关键因素。从抽油泵漏失量、阀球启闭造成的排量损失、泵腔未充满造成的排量损失及抽油杆、油管弹性变形对抽油泵排量影响等方面,分析了影响抽油泵排量的因素,并对每一种因素提出了相应的改进措施和建议。结果表明,游动阀球开启产生的轴向压力与抽油杆柱相互作用造成抽油杆柱弯曲所产生的冲程损失,以及抽油杆柱的弹性变形造成的冲程损失大大影响了抽油泵的排量及有效功率。建议现场根据油井实际工况选择抽油泵间隙。 展开更多
关键词 抽油泵 有效功率 排量分析 冲程损失
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脉搏轮廓温度稀释连续心排血量分析技术对休克抢救的指导价值 被引量:3
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作者 陆国平 闫钢风 《中国小儿急救医学》 CAS 2012年第3期224-227,共4页
休克是组织有效灌注不足或血流分布异常而导致的全身组织低灌注和脏器功能障碍。心输出量和组织灌注压是影响组织器官灌注的主要因素。因此,在休克诊断、治疗及评估过程中,及时了解血流动力学指标对于休克的救治极为关键。脉搏轮廓温... 休克是组织有效灌注不足或血流分布异常而导致的全身组织低灌注和脏器功能障碍。心输出量和组织灌注压是影响组织器官灌注的主要因素。因此,在休克诊断、治疗及评估过程中,及时了解血流动力学指标对于休克的救治极为关键。脉搏轮廓温度稀释连续心排血量分析法采用经肺热稀释技术和动脉波型曲线下面积分析技术,进行心输出量、后负荷及容量评估,是一项微创、低危、便捷、精确、连续监测心输出量技术,可为临床危重患儿提供一系列精确的血流动力学参数。 展开更多
关键词 脉搏轮廓温度稀释连续心量分析技术 休克 血流动力学
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非对称并行结构螺杆泵采油系统参数配置方法研究 被引量:4
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作者 童华仁 阎明印 +1 位作者 赵晶 王世杰 《机电工程》 CAS 北大核心 2023年第8期1194-1201,共8页
非对称并行结构螺杆泵采油系统,可以从根本解决推力球轴承限径、承载能力过小以及寿命短的问题。但是,目前非对称反旋向并行结构螺杆泵采油系统只有概念模型结构,尚未有人对双泵的参数配置方法进行研究。为此,提出了一种新型井下非对称... 非对称并行结构螺杆泵采油系统,可以从根本解决推力球轴承限径、承载能力过小以及寿命短的问题。但是,目前非对称反旋向并行结构螺杆泵采油系统只有概念模型结构,尚未有人对双泵的参数配置方法进行研究。为此,提出了一种新型井下非对称反旋向并行结构电机驱动螺杆泵采油系统。首先,基于“等寿命”理念开展了双螺杆泵的参数配置方法研究,给出了双泵匹配需要满足的约束条件,建立了易失效部件的受力分析模型,根据力平衡原理给出了部件之间的受力关系,分析了单螺杆泵转子所受轴向力和工作扭矩;然后,依据等寿命准则(推力球轴承与万向联轴器的疲劳使用寿命趋于相等),确定了推力球轴承所受轴向压力与联轴器所受拉力之间的比值关系,给出了上下两螺杆泵之间所受轴向力之比;最后,确定了定子橡胶寿命为一年及泵端压差12 MPa条件下,双泵参数匹配方案,对所选方案进行了寿命和排量对比分析,分析了不同泵端压差对下螺旋杆泵极限排量的影响。研究结果表明:针对特定推力球轴承和十字联轴节,下螺杆泵与上螺杆泵之间所受轴向力之比为1.41∶1;螺杆泵定子橡胶寿命一定,双泵的排量相比于单螺杆泵有了很大的提升,平均增长率在50%左右。 展开更多
关键词 双螺杆泵采油系统 双泵匹配约束条件 等寿命理念 轴向力和工作扭矩 泵端压差 寿命和排量分析
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玩具产品的碳足迹算法研究 被引量:1
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作者 杨小新 宋昌健 尚南 《环境科学与技术》 CAS CSCD 北大核心 2014年第S1期324-328,共5页
文章从产品碳足迹分析的方法入手,严格按照全球首个产品碳足迹方法标准(PAS 2050),经过确定产品生命周期、数据收集、信息计算、不确定性的评估等方法对磁石玩具进行了碳足迹信息的测算,得出产品的完整碳足迹信息。通过对产品生命周期... 文章从产品碳足迹分析的方法入手,严格按照全球首个产品碳足迹方法标准(PAS 2050),经过确定产品生命周期、数据收集、信息计算、不确定性的评估等方法对磁石玩具进行了碳足迹信息的测算,得出产品的完整碳足迹信息。通过对产品生命周期各阶段的碳排量进行分析,指导企业的低碳化生产。 展开更多
关键词 碳足迹测算 产品碳足迹 排量分析
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GRA BASED ANALYSIS ON FACTORS INFLUENCING CO_2 EMISSIONS IN CHINA 被引量:1
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作者 董锋 李晓晖 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2012年第2期152-158,共7页
How to achieve the objective of reducing CO2 emissions has been an academic focus in China recently. The factors influencing CO2 emissions are the vital issue to accomplish the arduous target. Firstly, three influenti... How to achieve the objective of reducing CO2 emissions has been an academic focus in China recently. The factors influencing CO2 emissions are the vital issue to accomplish the arduous target. Firstly, three influential factors, the energy consumption, the proportion of tertiary industry in gross domestic product (GDP), and the degree of dependence on foreign trade, are carefully selected, since all of them have closer grey relation with China's COz emissions compared with others when the grey relational analysis (GRA) method is applied. The study highlights co-integration relation of these four variables using the co-integration analysis method. And then a long-term co-integration equation and a short-term error correction model of China's CO2 emissions are devel- oped. Finally, the comparison is exerted between the forecast value and the actual value of China's CO2 emissions based on error correction model. The results and the relevant statistics tests show that the pro- posed model has better explanation capability and credibility. 展开更多
关键词 grey relational analysis(GRA) CO2 emissions co-integration test error correction model
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Principal Component Analysis of Major Pollutants Discharge Amount in Major Cities 被引量:1
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作者 于淼 金童 《Agricultural Science & Technology》 CAS 2017年第7期1260-1262,共3页
With the development of industry in China, the emission issues of indus- trial wastewater has got more and more attention. Excessive levels of pollutants in wastewater are urgent problem to be solved. Together with th... With the development of industry in China, the emission issues of indus- trial wastewater has got more and more attention. Excessive levels of pollutants in wastewater are urgent problem to be solved. Together with the emissions of do- mestic wastewater, the discharge amount of pollutants has exceeded standard in many cities, which not only pollutes the water resources, but also greatly threatens the environment, and does great harm to people's health. The principal component analysis was conducted based on the principal components extracted from the data of major pollutants emission conditions in the wastewater of major cities from the China Statistical Yearbook 2014. 展开更多
关键词 Principal component analysis Pollutant discharge amount Industrial wastewater: Domestic wastewater
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Inverse displacement analysis of the general six degree-of-freedom serial robot based on optimization method 被引量:1
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作者 赵永杰 《Journal of Chongqing University》 CAS 2011年第2期60-67,共8页
The paper presents a new solution of inverse displacement analysis of the general six degree-of-freedom serial robot.The inverse displacement analysis of the general serial robot is transformed into a minimization pro... The paper presents a new solution of inverse displacement analysis of the general six degree-of-freedom serial robot.The inverse displacement analysis of the general serial robot is transformed into a minimization problem and then the optimization method is adopted to solve the nonlinear least squares problem with the analytic form of new Jacobian matrix.In this way,joint variables of the general serial robot can be searched out quickly under the desired precision when positions of the three non-collinear end effector points are given.Compared with the general Newton iterative method,the proposed algorithm can search out the solution when the robot is at the singular configuration and the initial configuration used in the optimization method may also be the singular configuration.So the convergence domain is bigger than that of the general Newton iterative method.Another advantage of the proposed algorithm is that positions of the three non-collinear end effector points are usually much easier to be measured than the orientation of the end effector.The inverse displacement analysis of the general 6R(six-revolute-joint) serial robot is illustrated as an example and the simulation results verify the efficiency of the proposed algorithm.Because the three non-collinear points can be selected at random,the method can be applied to any other types of serial robots. 展开更多
关键词 inverse displacement analysis general serial robot optimization method
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Estimate of China's energy carbon emissions peak and analysis on electric power carbon emissions 被引量:7
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作者 WANG Zhi-Xuan ZHANG Jing-Jie +2 位作者 PAN Li YANG Fan SHI Li-Na 《Advances in Climate Change Research》 SCIE 2014年第4期181-188,共8页
China's energy carbon emissions are projected to peak in 2030 with approximately 110% of its 2020 level under the following conditions: 1) China's gross primary energy consumption is 5 Gtce in 2020 and 6 Gtce in 2... China's energy carbon emissions are projected to peak in 2030 with approximately 110% of its 2020 level under the following conditions: 1) China's gross primary energy consumption is 5 Gtce in 2020 and 6 Gtce in 2030; 2) coal's share of the energy consumption is 61% in 2020 and 55% in 2030; 3) non-fossil energy's share increases from 15% in 2020 to 20% in 2030; 4) through 2030, China's GDP grows at an average annual rate of 6%; 5) the annual energy consumption elasticity coefficient is 0.30 in average; and 6) the annual growth rate of energy consumption steadily reduces to within 1%. China's electricity generating capacity would be 1,990 GW, with 8,600 TW h of power generation output in 2020. Of that output 66% would be from coal, 5% from gas, and 29% from non-fossil energy. By 2030, electricity generating capacity would reach 3,170 GW with 11,900 TW h of power generation output. Of that output, 56% would be from coal, 6% from gas, and 37% from non-fossil energy. From 2020 to 2030, CO2 emissions from electric power would relatively fall by 0.2 Gt due to lower coal consumption, and rela- tively fall by nearly 0.3 Gt with the installation of more coal-fired cogeneration units. During 2020--2030, the portion of carbon emissions from electric power in China's energy consumption is projected to increase by 3.4 percentage points. Although the carbon emissions from electric power would keep increasing to 118% of the 2020 level in 2030, the electric power industry would continue to play a decisive role in achieving the goal of increase in non-fossil energy use. This study proposes countermeasures and recommendations to control carbon emissions peak, including energy system optimization, green-coal-fired electricity generation, and demand side management. 展开更多
关键词 Energy consumption Growth rate Carbon emissions peak Electric power development
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Impacts of tourism development on the physical environment of Mussoorie,a hill station in the lower Himalayan range of India 被引量:5
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作者 Sangeeta SUNDRIYAL Vijay SHRIDHAR +2 位作者 Sandeep MADHWAL Kamal PANDEY Vikram SHARMA 《Journal of Mountain Science》 SCIE CSCD 2018年第10期2276-2291,共16页
Tourism in mountainous regions is a significant source of revenue generation. However, it has also been associated with many adverse environmental consequences. This study aims at assessing the negative impacts of the... Tourism in mountainous regions is a significant source of revenue generation. However, it has also been associated with many adverse environmental consequences. This study aims at assessing the negative impacts of the incessant upsurge in tourism development on the physical environment of Mussoorie, a well-known mountain tourist destination in India. The impact indicators for the region were identified and assessed by qualitative and quantitative analysis of field observations. The observations indicated the aggravation of traffic congestion, atmospheric pollution, undisposed solid waste, water scarcity and infrastructure unavailability as the prevalent issues, especially during the peak tourist months. The extent of the consequential damage to the environment was evaluated by conducting an assessment of tourism-induced human disturbance on the natural landscape of the town. Slope, slope aspect, vegetation cover, road network and drainage network were incorporated as thedetermining landscape attributes to prepare thematic maps of landscape quality(perceivable intrinsic properties) and landscape fragility(vulnerability to anthropogenic disturbances) using GIS technique. An absorption capacity map was finally prepared to characterize the study area into regions of different conservation needs. The results identified the need for planning appropriate preservation strategies for different tourist places in the town. The study can be used by the policy makers for implementing the regulatory measures against potential disturbances due to mass-tourism. 展开更多
关键词 Absorption capacity Analytical Hierarchy Process Geographic Information System Human interventions Landscape assessment Mountain Tourism Destination
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Factor Analysis on Quantity of Discharged Pollutants in Wastewater in Major Cities 被引量:1
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作者 赵双蕊 《Agricultural Science & Technology》 CAS 2016年第4期964-967,共4页
The research performed statistical analysis on 186 data concerning the amount of discharged industrial wastewater, the amount of oxygen demand of industrial wastewater, the amount of ammonia and nitrogen discharged fr... The research performed statistical analysis on 186 data concerning the amount of discharged industrial wastewater, the amount of oxygen demand of industrial wastewater, the amount of ammonia and nitrogen discharged from industries, the amount of urban discharged domestic sewage, the amount of daily life chemical oxygen demand, and the amount of domestic ammonia and nitrogen to explore source of pollutants from wastewater and guarantee urban water quality.Factor analysis was then performed with SPSS according to discharge quantity of pollutants. The results should that the major pollutants are from domestic sewage it is expected scientific suggestions be proposed on water quality in our country. 展开更多
关键词 Quantity of discharged pollutants in wastewater Factor analysis SPSS
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Influence of mining thickness to the mechanical characteristics of gateways at FMTC faces 被引量:1
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作者 谢广祥 王磊 《Journal of Coal Science & Engineering(China)》 2008年第1期1-5,共5页
To make a better understanding of the mechanical characteristics of the surrounding rocks in the tailentry and headentry with different coal seam thickness at fully mechanized top-coal caving face (FMTC face), the s... To make a better understanding of the mechanical characteristics of the surrounding rocks in the tailentry and headentry with different coal seam thickness at fully mechanized top-coal caving face (FMTC face), the stress transition and displacement around the periphery of the gateways with different coal thicknesses were investigated in details by means of in situ measurement and 3-D numerical simulation. The research shows that the stresses decrease in the two spallings of the headentry and floor at goal with the increase in mining thickness. The roof pressure in the gates does not change obviously with the coal thickness, but the thicker the coal seam is, the farther the maximum stress will apply to the coal rib at the working face. The vertical stress is higher than the horizontal stress at two spallings of the gate, while its horizontal stress is higher than the vertical stress at the roof. The relative displacement between the roof and floor and the two spallings in the gateways increases gradually with the increase in coal seam thickness in a definite range in front of the face. Near the mining face, the stress decreases in the surrounding rock of the gates, while the deformation appears the most intensive. It is proposed that the support concept to the tailentry and headentry should be changed from loading control to deformation control. 展开更多
关键词 FMTC face coal seam thickness GATEWAYS STRESS DISPLACEMENT
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Effects of China's OFDI on Host Countries' Environmental Quality 被引量:1
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作者 刘玉博 吴万宗 《China Economist》 2017年第5期110-123,共14页
From a FDI source country perspective, this paper reveals the effect of Chinas OFDI on host countries' environmental quality. Based on the Copeland-Taylor model, this paper creates a theoretical mechanism to demon... From a FDI source country perspective, this paper reveals the effect of Chinas OFDI on host countries' environmental quality. Based on the Copeland-Taylor model, this paper creates a theoretical mechanism to demonstrate how Chinas OFDI affects host countries' pollution intensity and environmental quality and carries out an empirical analysis based on Chinas OFDI data of 2003-2014 and the economic development index data of 168 host countries. Since Chinas OFDI is differentiated for countries of various income levels, this paper f Urther conducts a sub-sample empirical test on the income level of host countries. The result shows that Chinas OFDI growth generally induces an increase in total pollution emissions in host countries but significantly reduces per capita emissions and thus improves local environmental quality. Sub-sample regression result shows that whether in terms of total or per capita emissions, Chinas OFDI has a much more significant effect in improving the environmental quality of high-income countries. 展开更多
关键词 OFDI environmental quality Copeland-Taylor model
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A Model of Shield Jack Thrust to Shield Attitude
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作者 郭正刚 孙伟 岳明 《Journal of Donghua University(English Edition)》 EI CAS 2011年第2期124-127,共4页
The attitude of the shield tunneling machine (or "shield" for short) during tunneling is important to tunnel excavation and construction quality, which results from a combination of jack thrust, ground displ... The attitude of the shield tunneling machine (or "shield" for short) during tunneling is important to tunnel excavation and construction quality, which results from a combination of jack thrust, ground displacement around the shield, and ground mechanics parameters, etc. A shield attitude model involving elements above was proposed. In this model, ground displacement was taken to calculate the load around the shield. Ground mechanics parameters were involved. Based on the shield load model, the needed jack thrust for shield desired attitude was derived. The proposed method is validated using engineering data, and lays reliable foundation for shield attitude control. 展开更多
关键词 SHIELD ground displacement analysis jack thrust attitude control
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Forward displacement analysis of a redundant parallel manipulator by approximation algorithms
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作者 赵永杰 邱可 《Journal of Chongqing University》 CAS 2010年第1期12-20,共9页
This paper presents the forward displacement analysis of an 8-PSS(prismatic-spherical-spherical)redundant parallel manipulator whose moving platform is linked to the base platform by eight kinemtic chains consisting o... This paper presents the forward displacement analysis of an 8-PSS(prismatic-spherical-spherical)redundant parallel manipulator whose moving platform is linked to the base platform by eight kinemtic chains consisting of a PSS joint and a strut with fixed length.A general approximation algorithm is used to solve the problem.To avoid the extraction of root in the approximation process,the forward displacement analysis of the 8-PSS redundant parallel manipulator is transformed into another equivalent problem on the assumption that the strut is extensible while the slider is fixed.The problem is solved by a modified approximation algorithm which predicates that the manipulator will move along a pose vector to reduce the difference between the desired configuration and an instantaneous one,and the best movement should be with minimum norm and least quadratic sum.The characteristic of this modified algorithm is that its convergence domain is larger than that of the general approximation algorithm.Simulation results show that the modelified algorithm is general and can be used for the forward displacement analysis of the redundant parallel manipulator actuated by a revolute joint. 展开更多
关键词 redundant narallel maninulator: forward displacement analvsis: annroximation algorithm
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Empirically Analysis of the CO_2 Emissions Embodied in Exports of China 被引量:1
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作者 Zhu Qirong 《Chinese Journal of Population,Resources and Environment》 2011年第3期86-96,共11页
In this paper,using the input-output model,the author first calculated the CO 2 emissions embodied in exports of China in 2002 and 2007.Then,the author empirically analyzed problems existing in the composition of expo... In this paper,using the input-output model,the author first calculated the CO 2 emissions embodied in exports of China in 2002 and 2007.Then,the author empirically analyzed problems existing in the composition of exported products and analyzed its possible reasons.The research results of this paper are as follows:Since China's entry into WTO,the CO 2 emissions embodied in exports of China have been increasing rapidly;the value of exported products of high-carbon emissions industries accounts for a relatively higher proportion to China's total exports value because China's carbon intensive products have a certain competitive advantage.Additionally,this paper has put forward relevant suggestions based on these results. 展开更多
关键词 EXPORTS CO2 emissions carbon intensive prod-ucts inputoutput model
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Carbon emissions of China's industrial sectors based on input-output analysis
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作者 Xiaohong Yu Miao Xu Yumeng Ding 《Chinese Journal of Population,Resources and Environment》 2017年第2期147-156,共10页
This study uses an input-output model presenting the embodied carbon emission in the importexport procedure, as well as the responsibility allocation between China's 35 sectors and 7 main trade partners from 1995 ... This study uses an input-output model presenting the embodied carbon emission in the importexport procedure, as well as the responsibility allocation between China's 35 sectors and 7 main trade partners from 1995 to 2011. Results indicate that the amount of carbon emissions in China's industrial sectors is immense and that the industrial sectors are in serious imbalance. Such imbalance exists mainly in textiles, basic and fabricated metal, electrical and optical equipment,and machinery, among others. Based on the consumer-responsibility principle, the responsibility of 29 departments is reduced. Correspondingly, foreign sectors become more responsible.America, as China's largest trading partner, should account for most of the total responsibility,followed by developed countries such as Japan, South Korea, and Germany. 展开更多
关键词 Consumer-responsibility principle industrial sectors trade carbon emission
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Characteristics and Cause Analysis of Heavy Haze in Changchun City in Northeast China 被引量:8
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作者 MA Siqi CHEN Weiwei +3 位作者 ZHANG Shichun TONG Quansong BAO Qiuyang GAO Zongting 《Chinese Geographical Science》 SCIE CSCD 2017年第6期989-1002,共14页
Northeast China has been reported as having serious air pollution in China with increasing occurrences of severe haze epi- sodes. Changchun City, as the center of Northeast China, has longstanding industry and is an i... Northeast China has been reported as having serious air pollution in China with increasing occurrences of severe haze epi- sodes. Changchun City, as the center of Northeast China, has longstanding industry and is an important agricultural base. Additionally, Changchun City has a long winter requiring heating of buildings emitting pollution into the air. These factors contribute to the complex- ity of haze pollution in this area. In order to analyze the causes of heavy haze, surface air quality has been monitored from 2013 to 2015. By using satellite and meteorological data, atmospheric pollution status, spatio-temporal variations and formation have been analyzed. Results indicated that the air quality in 88.9% of days exceeding air quality index (AQI) level-1 standard (AQI 〉50) according to the National Ambient Air Quality Standard (NAAQS) of China. Conversely, 33.7% of the days showed a higher level with AQI 〉 100. Ex- treme haze events (AQI 〉 300) occurred frequently during agricultural harvesting period (from October 10 to November 10), intensive winter heating period (from Late-December to February) and period of spring windblown dust (April and May). Most daily concentra- tions of gaseous pollutants, i.e., NO2 (43.8 gg/m3), CO (0.9 mg/m3), SO2 (37.9 gg/m3), and 03 (74.9 gg/m3) were evaluated within level-1 concentration limits of NAAQS standards. However, particulate matter (PM2.5 and PMI0) concentrations (67.3 ~tg/m3and 115.2 ~g/m3, respectively) were significantly higher than their level-1 limits. Severe haze in spring was caused by offsite transported dust and windblown surface soil. Heavy haze periods during fall and winter were mainly formed by intensive emissions of atmospheric pollutants and steady weather conditions (i.e., low wind speed and inversion layer). The overlay emissions of widespread straw burning and coal combustion for heating were the dominant factors contributing to haze in autumn, while intensive coal burning during the coldest time was the primary component of total emissions. In addition, general emissions including automobile exhaust, road and construction dust, residential and industrial activities, have significantly increased in recent years, making heavy haze a more frequent occurrence. There- fore, both improved technological strategies and optimized pollution management on a regional scale are necessary to minimize emis- sions in specified seasons in Changchun City, as well as comprehensive control measures in Northeast China. 展开更多
关键词 air quality air quality index (AQI) air pollutant heavy haze event Changchun City
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Traffic analysis on carrier accessing for WLAN indoor positioning system
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作者 马琳 秦丹阳 徐玉滨 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2012年第2期113-118,共6页
Currently,the WLAN indoor positioning system attracts a lot of interests,not only because of the cheap implementation but also because of the high positioning accuracy comparing with other indoor positioning systems.T... Currently,the WLAN indoor positioning system attracts a lot of interests,not only because of the cheap implementation but also because of the high positioning accuracy comparing with other indoor positioning systems.The WLAN indoor positioning system contains two phases,which are offline phase and online phase.In the online phase,the WLAN equipment user(UE) has to access to the WLAN for the latest radio map and positioning software.Due to during the network allocation vector(NAV) duration,the WLAN channel is only reserved for one WLAN UE,others UEs' carrier accessing will be blocked.In addition,the blocked UE will make a retrial accessing,which will definitely introduce more traffic blocking to the WLAN.So In this paper,based on the analysis of the WLAN indoor positioning system architecture,a proper queuing model by using of the Extended Erlang B formula is proposed,which takes the retrial calling percentage into consideration in the proposed model.The simulation results show that the proposed method is more accurate and performs well to predict the blocking probability. 展开更多
关键词 WLAN i extended Erlang B blocking probability Queue theory recalling factor
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Development of the Interurban Service with the Use of Alternative Commercial Road Trains
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《Journal of Civil Engineering and Architecture》 2012年第1期12-25,共14页
The main task of this paper is to review the principal aspects in organization of interurban long haul service with the use of road trains on the basis of the "district" traffic system. The goal of the paper is to d... The main task of this paper is to review the principal aspects in organization of interurban long haul service with the use of road trains on the basis of the "district" traffic system. The goal of the paper is to determine the most effective methods of trucking operations in order to highlight the regularities that characterize these methods. The paper describes practicable methods of freight flow analysis, some factors and parameters concerning movement of motor-vehicle trains and original route schedules as well. Of special interest is the obtained algorithm of economically effective trucking operations of motor-vehicle trains on the route. 展开更多
关键词 Through system district system truck (hybrid) tractor detachable semi-trailer route section (district).
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