基于MODIS数据反演江浙皖地区气溶胶光学厚度

气溶胶是气候变化和大气污染的重要影响因素。人们发现卫星遥感为大面积获取气溶胶光学厚度提供了手段,同时卫星遥感的气溶胶光学厚度弥补了地面观测空间覆盖不足的缺陷。文章首先介绍了使用暗像元法反演气溶胶光学厚度的算法和计算流程,利用传统的暗像元法和改进的暗像元法(即V5.2算法)反演江浙皖地区(29～33°N;116～120°E)气溶胶光学厚度的空间分布,并对两种算法所得结果进行比较与分析。结果表明:暗像元法基本可以反映出该区域气溶胶光学厚度的空间分布特点,尤其是在浓密植被区卫星反演得到的结果与(AERONET)太阳光度计的观测值基本相近。但是在城市地区,该算法得到的结果与观测值存在一定的偏差,有待于进一步改善。     

Critical flow-storm approach to total maximum daily load(TMDL) development: an analytical conceptual model

One of the key challenges in the total maximum daily load (TMDL) development process is how to define the critical condition for a receiving waterbody. The main concern in using a continuous simulation approach is the absence of any guarantee that the most critical condition will be captured during the selected representative hydrologic period, given the scarcity of long-term continuous data. The objectives of this paper are to clearly address the critical condition in the TMDL development process and to compare continuous and event-based approaches in defining critical condition during TMDL development for a waterbody impacted by both point and nonpoint source pollution. A practical, event-based critical flow-storm (CFS) approach was developed to explicitly addresses the critical condition as a combination of a low stream flow and a storm event of a selected magnitude, both having certain frequencies of occurrence. This paper illustrated the CFS concept and provided its theoretical basis using a derived analytical conceptual model. The CFS approach clearly defined a critical condition, obtained reasonable results and could be considered as an alternative method in TMDL development.     

基于“纵深防御”原则的危化企业事故预防系统建立

危险化学品生产是当前的高危行业和安全管理的重点领域。面对事故频发的严峻形势,如何开展好危险化学品生产企业的安全管理,建立事故预防系统防止事故的发生非常关键。“纵深防御”原则作为核电厂实现核安全的一项基本原则,为核电厂长期稳定安全的发展奠定了坚实的基础,对危化企业提升事故预防能力,建立事故预防系统有较强的借鉴意义。借鉴“纵深防御”原则,文章分析危化企业应用“纵深防御”原则预防和减少事故发生的必要性,结合生产特点建立了事故纵深防御系统,对企业提高安全管理水平,预防事故的发生有重要的意义。     

用于湿法净化黑烟表面活性剂筛选的数学模型研究

湿法净化燃煤窑炉中的黑烟,关键在于表面活性剂对炭黑的润湿、增溶和降低表面张力作用.根据研究筛选的数学模型,计算AEO-9和SDBS混合表面活性剂溶液的亲水亲油平衡值HLB、临界胶束浓度CMC与胶束形成吉布斯自由能ΔG0mf.通过实验测得不同配比AEO-9和SDBS溶液的CMC和处于该CMC时黑烟的去除效率η,分析混合溶液中HLB、CMC、ΔG0mf与η的关系,建立新的数学模型.结果表明,理论CMC与实测CMC吻合度较好;HLB与ln[CMC]线性相关;ΔG0mf与η存在二次函数关系.降低CMC可以有效增大HLB,增加溶解度,减小形成胶束的吉布斯自由能,降低表面张力,使形成胶束的反应更容易自发进行,有效提高黑烟去除效率.     

丁羟推进剂贮存老化的动态力学性能

采用动态热分析(DMA)方法研究了某丁羟推进剂贮存老化的动态力学性能,借助时间一温度叠加原理,获得时间位移与频率对数的关系曲线及WLF方程的常数,并计算得到固体火箭发动机点火瞬间的推进剂药柱的临界温度tc,并用tc数据预估了发动机点火瞬间推进剂药柱不会由高弹态向玻璃态转变,不会发生断裂与结构完整性破坏.     

深度及含水率对包气带砂层中柴油降解作用的影响

通过模拟砂柱实验,研究了不同深度及含水率砂层(包括细砂、中砂和粗砂)中的柴油降解特性.结果表明,介质的深度及含水率是影响柴油降解效率的重要因素.相同介质条件下,介质的含水率越大,其生物活性越强,生物作用降解柴油的效率越高.介质性质影响柴油在包气带介质中的降解效率,介质的颗粒越细,其降解柴油的能力越高,即细砂>中砂>粗砂...     

China’s Total Emission Control Policy: A Critical Review

Abstract

As part of a comprehensive environmental management system, many countries establish emission control targets for mass emissions of a pollutant. Such targets are often the key objective of an environmental policy, such as an emission trading program. In China, however, it is more than just an objective of one particular policy; it has become a concept that has influenced many national environmental policies and activities. The objective of this article is to review the implementation of the total emission control policy in the past 10 years and explore emerging issues in its implementation. The article has three sections: a summary of the implementation experience, issues with the design and implementation of the policy, and policy recommendations.     

Identifying the factors influencing the performance of reverse supply chains (RSC)

This paper aims to extract the factors influencing the performance of reverse supply chains (RSCs) based on the structure equation model (SEM). We first introduce the definition of RSC and describe its current status and follow this with a literature review of previous RSC studies and the technology acceptance model . We next develop our research model and 11 hypotheses and then use SEM to test our model and identify those factors that actually influence the success of RSC. Next, we use both questionnaire and web‐based methods to survey five companies which have RSC operation experience in China and Korea. Using the 168 responses, we used measurement modeling test and SEM to validate our proposed hypotheses. As a result, nine hypotheses were accepted while two were rejected. We found that ease of use, perceived usefulness, service quality, channel relationship and RSC cost were the five most important factors which influence the success of RSC. Finally, we conclude by highlighting our research contribution and propose future research.     

应用GIS方法反演洪水最大淹没水深的空间分布研究

探讨了应用地理信息系统（GIS）方法反演洪水最大淹没水深的基本原理和计算方法。对水库型淹没区和滩地型淹没区分别进行了分析和讨论。以1960年辽东洪水作为实例，在1：1万比例尺地形数据的支持下，结合历史洪水洪痕水位调查资料，计算了该次洪水最大淹没水深的空产布状况，计算结果可以为洪灾损失评估和洪灾风险评价提供数据基础。     

Evolution of soil fertility and nitrogen/phosphorus leaching risk in protected agriculture of the eastern Qinghai-Tibet Plateau北大核心CSCD

Understanding changes in soil fertility and soil environmental risks in protected agriculture with high irrigation and fertilizer inputs are of great significance for ecological protection. In this study, soil samples in the plow layer were collected from greenhouses >100 acres in the eastern Qinghai-Tibet Plateau after different durations of planting time (either ≤ 3, 3-5, 5-10, or 10-20 years) to assess the changing pattern of soil fertility indicators and the potential leaching risk of nitrogen and phosphorus. The results showed that soil organic matter (OM) and total nitrogen (TN) contents in protected agriculture were 17.1 and 1.3 g/kg, respectively, which suggests moderate content levels. Meanwhile, soil alkali-hydrolyzed nitrogen (AN), available phosphorus (Olsen-P), and available potassium (AK) contents were 160.9, 72.0, and 191.2 mg/kg, respectively, which suggests abundant content levels. As the number of planting years increased, the contents of soil OM, TN, AN, and Olsen-P increased significantly, especially after 10 years, with 41.6%, 44.2%, 26.5%, and 67.4% increases, respectively, compared to ≤ 3 years. As seen, Olsen-P had the most marked increase. In contrast, soil AK and pH decreased with planting years, and soil AK after 5 years decreased by 32% compared to ≤ 3 years. Moreover, the soil pH value in 3-5 years decreased by 2.3% compared to that of ≤ 3 years. The leaching risk of soil nitrogen and phosphorus was intensified after 10-20 years, and the probability of leaching was 0.74 and 0.84, respectively. This study indicated that, in protected agriculture, soil OM, AN, and Olsen-P contents improved, accompanied by a high risk of N and P loss, and AK and soil pH values decreased. It is recommended that the input of nitrogen and phosphorus fertilizers should be controlled, and the input of potassium fertilizer should be increased for more than 10 years of facility cultivation. This study provides a scientific basis for the rational fertilization of agricultural facilities. The findings indicate that after facility planting for 10-20 years, soil organic matter, nitrogen, and phosphorus significantly increased, yet the leaching risk of nitrogen and phosphorus increased as well, suggesting that the input of nitrogen and phosphorus fertilizer should be controlled. After 3-5 years of planting, soil AK and pH values decreased significantly, implicating that potassium and organic fertilizer should be supplemented in a timely manner. © 2022 Science Press. All rights reserved.