An easy method to design gas/vapor relief system with rupture disk

Tank discharge gas/vapor flow problems are frequently encountered in both practice and design. To perform this type of design calculation, the first step is to identify whether the flow is choked or not through a trial-and-error solution of an equation for adiabatic flow with friction from a reservoir through a pipe. Developing a direct method without any trial-and-error to identify a choking condition would be helpful for expediting the flow calculations. This paper presents an easy and quick method to identify the choking of gas flow for an emergency relief system consisting of a rupture disk and vent piping. This greatly simplifies the design calculations. The proposed method for validating the venting adequacy of existing ERS circumvents the iteration calculation and the use of Lapple charts. Three case studies for the design of vent piping for rupture disks support the proposed method.     

生态文明建设实现合作治理的条件、主体和路径分析研究

生态文明建设是政府、市场、非政府组织和公民等多元主体合作治理的整体性系统性实践活动,多元主体合作治理的实现依赖于制度环境、组织因素、共同目标和信息沟通等多个关键条件,同时,合作治理需要各主体按照生态文明建设的要求明确和重塑角色定位,进而通过健全多元主体参与生态文明建设法律保障体系,健全生态补偿和生态支出竞争使用机制,建立信息交互制度,寻求多元合作模式,最终实现统筹协调、联动增效的生态文明建设合作治理.     

Rangeland dynamics of southern Ethiopia: (2). Assessment of woody vegetation structure in relation to land use and distance from water in semi-arid Borana rangelands

The structure and advancement of woody vegetation was studied in a semi-arid rangeland of southern Ethiopia under three land-use systems (communal land, a government ranch and a traditional grazing reserve enclosure) and along a distance gradient (near, middle and far) from water sources. A total of 54 woody plant species were identified. Based on the subjective opinions of the pastoralists, 85% of the identified woody plants have forage values to livestock. Cadaba farinsoa, Ormocarpum trichocarpum, Rhus natalensis, Acacia brevispica, Cordia gharaf and Hibiscus sparseaculeatus were reported to have fair to good palatability. Tree equivalent (TE) density of all woody plants combined was greater (P <0.01) in the government ranch (1) 188 TE ha(-1)) and the communal land (1083 TE ha(-1)) than in the traditional grazing reserve (419 TE ha(-1)), whereas this did not vary significantly (P >0.05) along the distance gradient from water. The most important encroaching woody plant species in the study areas were in descending order: Commiphora africana, Acacia drepanolobium, A. brevispica, Acacia. tortilis, Grewia tembensis and Lannea floccosa. The density of individual encroaching woody plant species along the distance gradient from water was not consistent. All encroaching woody species had the highest TE density in the communal land. The prevalence of these species followed the pattern of intensity of use within the communal grazing area. Most of the woody species had the highest abundance in the height class >0-2m regardless of land use and distance gradient from water. This study investigated the advance of severe woody encroachment in the communal and government sites as well as along the distance gradient from water. Some of the important contributing factors that can be suggested are heavy grazing pressure (in both the communal and government sites), expansion of cultivation and reduced mobility of livestock due to settlement of the pastoralists in the communal land.     

基于函数极值条件下的中国碳达峰碳中和情景分析

基于函数极值条件提出了碳达峰出现时间和需要满足的理论条件,并对主要发达国家作了验证,同时对中国现状做了分析,最后采用了基准和强化两种情景分析了中国实现2030年碳达峰后进入2060年碳中和时期的二氧化碳排放量。研究结果显示：（1）根据IPAT恒等式将碳排放函数分解成人口、人均GDP和碳强度三个因素时,碳峰值出现时间为三个因素年增长率之和由正转负的正数值年度,发达国家的历史数据证实了这一条件。（2）中国三个因素年增长率之和自2003年起已经开始降低,最近几年一直在0.01~0.02徘徊,表明总体上朝着有利于碳达峰的方向发展,同时按照三个因素的预期发展目标计算得出中国2030年碳排放峰值的上限为112.2亿t,若2021—2035年保持相同的人均GDP年均复合增长率,碳强度年均复合增长率的绝对值需要比人均GDP年均复合增长率高0.14个百分点。（3）在能源消费总量逐渐回落的前提条件下,2060年基准情景下非化石能源占比约为65%,产生的二氧化碳量约为31.4亿t,强化情景下非化石能源占比约为70%,二氧化碳排放约为26.6亿t,而碳汇和CCUS等固碳技术还存在不确定性,碳中和任务依然艰巨。实现碳达峰碳中和最终需要控制能源消费,践行低碳消费行为。     

Household income,living and working conditions of dumpsite waste pickers in Bantar Gebang: Toward integrated waste management in Indonesia

This paper clarifies household income, living and working conditions of dumpsite waste pickers at Bantar Gebang final disposal site for municipal solid waste generated in Jakarta, and investigates the feasibility of integrating the informal sector into formal waste management in Indonesia. The first author did fieldwork for totally 16 months at the site and quantitative field surveys were conducted twice during the period. All respondents in the first round quantitative survey (n = 1390) were categorized as follows: waste pickers, family workers, wage labors, bosses, family of the bosses, housewives, pupils/students, preschoolers, the unemployed, and others. Based on the results of the second round quantitative survey (n = 69 households), their average household income was estimated to be approximately US 216 dollars per month (n = 59 households), which was virtually equivalent to the minimum wage in Jakarta in 2013. Living conditions of scavengers at the site were horrible, and their working conditions were dangerous due to medical waste and other sharp waste. Polluted groundwater was one of the serious environmental problems at the site. Despite the social, health and environmental problems, they were attracted to the freedom of entering the informal recycling system in Bantar Gebang and withdrawing from the system, in which a lot of opportunities were provided for the people having few marketable skills to obtain cash earnings. The freedom of their choice should be guaranteed as a prerequisite before integrating the informal sector into formal waste management. Furthermore, special attentions are required when incomes of scavengers are the same level as minimum wages and the national economy is rapidly growing, because scavengers cannot easily change their jobs due to few marketable skills. Indonesian national waste laws and regulations should be properly applied to facilitate a socialization process at final disposal sites. Measures need to be taken to prevent children from working as informal recycling actors, especially for waste pickers aged 15 or younger.     

陕西省1990年自然灾害和救灾工作回顾：兼谈1991年减灾对策

本文在回顾1990年陕西省灾情及救灾工作基础上,提出了强化政府在减灾中的职能,搞好灾情预测预报、及早制定防灾预案及灾前准备工作的减灾对策。     

农业开发的企业化经营

目前企业化经营已被越来越多地运用于农业开发的生产管理中。本文阐述了农业开发中企业化经营形式及其重要性,分析了当前企业化经营优势尚未充分发挥的原因,提出了加强农业开发企业化管理的对策。     

Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016

With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O_3,decreased. Spatially, the PM_(2.5), PM_(10), SO_2, and CO concentrations were higher in the northern YRD region, and NO_2 and O_3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM_(2.5) was the largest contributor to air pollution in the YRD region, followed by O_3, PM_(10), and NO_2.However, particulate matter pollution has declined gradually, while O_3 pollution worsened.Meteorological conditions mainly influenced day-to-day variations in pollutant concentrations. PM_(2.5) concentration was inversely related to wind speed, while O_3 concentration was positively correlated with temperature and negatively correlated with relative humidity.The air quality improvement in recent years was mainly attributed to emission reductions.During 2014–2016, PM_(2.5), PM_(10), SO_2, NO_x, CO, NH_3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region.     

不同工况下轻型车油耗试验驾驶方式评价

在一台性能稳定的汽油车上由同一驾驶人员按平顺、粗暴和正常3种驾驶方式分别进行NEDC （新欧洲行驶工况）、FTP75（美国认证工况）以及WLTC （世界统一轻型车测试循环）工况油耗试验,采用能量变化率（ER）、距离变化率（DR）、能量经济性变化率（EER）、绝对速度改变率（ASCR）、速度平方根误差（RMSSE）以及惯性做功改变率（IWR）6个指标作为驾驶质量评价指标,通过分析计算每次试验各项评价指标及其与燃料消耗量变化的相关性,确定了油耗试验驾驶方式的合理性边界条件.结果表明,对于WLTC和FTP75工况,平顺驾驶和粗暴驾驶均会导致评价指标变大或者变小,驾驶方式与评价指标呈规律性变化;对于NEDC工况,不同的驾驶方式对NEDC工况油耗影响较小.油耗试验的边界条件,WLTC工况的EER为（0.25±0.47）%、ASCR为（1.20±0.97）%、RMSSE为（0.85+0.15）km/h、IWR为（2.15±1.27）%时,可认为油耗试验的驾驶方式较为合理;FTP75工况的EER为（-0.09±0.69）%、ASCR为（-0.59±0.42）%、RMSSE为（0.88+0.34）km/h以及IWR为（-0.69±1.66）%时,油耗试验的驾驶方式较为合理.     

西南喀斯特流域枯季地下水电导率特征及水-岩作用分析

受特殊水文地质条件影响,西南喀斯特流域水动力过程与物质循环过程复杂,利用单一水文信息分析该地区水动力过程具有较大难度。地下水电导率受喀斯特水文地质条件影响显著,可以综合反映区域水动力条件与岩性特征。论文选取贵州普定县后寨河流域为研究区,通过野外调查及地下水电导率原位测定,结合流域地形、岩性及落水洞、岩溶泉等岩溶地貌空间分布规律,分析了喀斯特流域枯季地下水电导率空间分布及其受水-岩特征的影响。结果表明,山丘区地下水电导率较低,主要由于喀斯特山区是岩溶裂隙/管道网络发育的强径流区,水-岩接触时间较短。随高程降低,地下水电导率呈现增加趋势,表明地下水流速度减缓,水-岩接触时间变长。地下水电导率受岩性特征影响显著,石灰岩区水-岩作用强烈,易形成较高电导率地下水,平均电导率650 μS/cm,白云岩区水-岩作用减弱,地下水电导率降低,平均值523 μS/cm。