0.1～3000MHz射频电磁环境时间变化规律及其与人群作息时间关系的研究

利用自动连续监测仪器对在成都市城区选定的监测点位开展了持续数日的测量,获取了测点的长时间监测数据,通过对监测数据的分析,研究了0.1~3000MHz射频电磁环境随时间变化的规律及其与人群作息时间的关系,并对电磁环境人工手动监测的适宜时间段进行了分析。     

Co-pyrolysis of swine manure with agricultural plastic waste: Laboratory-scale study

Manure-derived biochar is the solid product resulting from pyrolysis of animal manures. It has considerable potential both to improve soil quality with high levels of nutrients and to reduce contaminants in water and soil. However, the combustible gas produced from manure pyrolysis generally does not provide enough energy to sustain the pyrolysis process. Supplementing this process may be achieved with spent agricultural plastic films; these feedstocks have large amounts of available energy. Plastic films are often used in soil fumigation. They are usually disposed in landfills, which is wasteful, expensive, and environmentally unsustainable. The objective of this work was to investigate both the energetics of co-pyrolyzing swine solids with spent plastic mulch films (SPM) and the characteristics of its gas, liquid, and solid byproducts. The heating value of the product gas from co-pyrolysis was found to be much higher than that of natural gas; furthermore, the gas had no detectable toxic fumigants. Energetically, sustaining pyrolysis of the swine solids through the energy of the product gas could be achieved by co-pyrolyzing dewatered swine solids (25% m/m) with just 10% SPM. If more than 10% SPM is used, the co-pyrolysis would generate surplus energy which could be used for power generation. Biochars produced from co-pyrolyzing SPM and swine solid were similar to swine solid alone based on the surface area and the ¹H NMR spectra. The results of this study demonstrated the potential of using pyrolysis technology to manage two prominent agricultural waste streams (SPM and swine solids) while producing value-added biochar and a power source that could be used for local farm operations.     

具有变频器的矿井低压漏电保护研究

为了解决移动变电站低压侧为变频器供电时漏电保护装置误动的问题，提出了基于傅式算法的附加直流原理漏电保护新方法。通过理论分析和MATLAB/Simulink仿真，研究了具有变频器的矿井低压供电系统附加直流原理漏电保护，提出由傅式算法分解出采样电压直流分量以反映电缆绝缘水平的保护方法；同时分析了其他因素对直流分量的影响。研究结果表明:变频器对传统附加直流保护整定值有较大影响，易造成漏电保护装置误动且无法实现电缆的在线绝缘监测；所提出的直流分量法能准确测量电缆对地绝缘电阻，且可消除电缆分布电容、变频器载波频率、变频器输出频率等其他因素的干扰；采用该漏电保护方法，可承受变频器投入时对采样电压造成的较大冲击，不必在启动期间解除漏电保护装置，能够消除在此期间存在的人身触电安全隐患。     

Brain myelination in rats treated with ionizing radiation in utero

Abstract

Effects of ionizing radiation on brain myelination and some physical development parameters were studied in laboratory rats (Fisher F‐344 inbred strain). Rats were treated with three different doses of radiation (150 rad, 15 rad, and 6.8 rad) delivered on the 20th day of prenatal life. Exposure to 150 rad reduced body, brain, ovary, kidney, heart and spleen weights. Prenatal exposure to 150 rad of radiation reduced the cerebral cortex weight by 22 percent at 30 days of age, and 20 percent at 52 days of age which caused a reduction in cerebral cortex myelin content by 20 and 23 percent at the ages of 30 and 52 days respectively. This dose did not affect the myelin content of the cerebellum or the brain stem, or the myelin concentration (mg myelin/g brain tissue) of the cerebral cortex, cerebellum, and the brain stem. The cerebral cortex weight of the 15 rad treated rats was reduced at the age of 30 days. Exposure to 15 rad, and 6.8 rad did not affect either the myelin content or the myelin concentration of these brain areas.     

Climate change,risk perception,and protection motivation among high-altitude residents of the Mt. Everest region in Nepal

Mountain ecosystems are considered vulnerable to early impacts of climate change. Whether and how local residents of these areas perceive these changes, however, remain under-studied questions. By conducting a household survey in the Khumbu region of Nepal, this study assessed local residents’ experience-based perception of changes in climate trends and patterns, perceived risk, and attitudes towards climate issues. Multivariate cluster analysis based on residents’ climate change beliefs revealed three segments: “Cautious,” “Disengaged,” and “Alarmed.” A comparison of these segments along key psychosocial constructs of Protection Motivation Theory (PMT) revealed significant inter-segment differences in residents’ perception of severity, vulnerability, response efficacy, self-efficacy, and response cost associated with engaging in mitigating behavior. Results shed light on how residents of high elevation areas that are considered to be exposed to early impacts of climate change perceive the risk and intend to respond. These findings could also assist stakeholders working in other similar mountain ecosystems in understanding vulnerability and in working towards climate readiness.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01369-x) contains supplementary material, which is available to authorized users.     

低碳经济背景下我国产业结构升级对策研究

为了实现我国经济的平稳发展,改变以"高消耗、高增长、高污染"的传统经济增长方式,解决资源的过度消耗和温室气体的过量排放等问题,文章从我国产业及内部结构、产业的碳排放量和产业节能率三个方面进行了分析,提出了在低碳经济背景下实现我国产业结构升级的对策。     

美国市政污水处理排放标准制定对中国的启示

在概述美国市政污水处理排放标准制度体系的基础上,介绍了其制定基于技术的排放限值和基于水质的排放限值的方法,阐述了其制定的科学性,并指出了中国市政污水处理排放标准中存在的相应问题。最后,根据美国制定排放标准限值的经验,对我国污水处理排放标准进行了思考,并提出了科学制定排放标准的方法和建议。     

环境保护系统参与空间规划的思考与建议

空间规划体系下,环境规划在空间落地性以及精细化程度上存在短板。建议环境规划进一步完善生态保护红线制度,探索环境质量底线、环保负面清单的划定技术思路与技术路线,推动环境保护系统化参与空间规划。     

铝合金-丁腈橡胶航空带垫卡箍典型环境损伤研究

目的研究典型环境对丁腈橡胶-铝合金带垫卡箍的损伤效应。方法通过模拟铝合金-丁腈橡胶航空带垫卡箍使用时的装配结构和应力状态,应用GJB 150A—2009中的湿热和太阳辐射两种典型老化环境,采用宏观形貌观察、卡箍保持力测试和橡胶衬垫拉伸性能测试方法,结合扫描电子显微镜和傅里叶红外光谱技术,分析带垫卡箍的性能劣化过程。结果带垫卡箍在湿热和太阳辐射环境中老化50 d后,卡箍橡胶衬垫表面出现大量微孔缺陷,拉伸性能大幅降低,导致卡箍保持力分别下降了35%和51%。结论带垫卡箍在模拟装配状态下进行湿热和太阳辐射环境暴露实验,卡箍橡胶衬垫内部结构由致密逐渐变得疏松,部分碳碳双键发生氧化交联反应,并在一定程度上提高了聚合物的交联密度,材料硬度提高,回弹性能减弱,橡胶衬垫对芯轴的包裹能力降低,导致卡箍保持力性能降低。     

基于预应力杆的空间桁架天线固有频率调节技术

目的研究预应力杆对大型空间桁架天线固有频率影响,提出采用作动器实时对在轨空间天线低阶固有频率进行调整,主动避免共振现象发生。方法针对大型空间桁架天线结构有限元模型,采用降温法对桁架杆施加预应力,重点分析预应力大小、预应力杆位置、预应力杆数量对整体结构固有频率的影响。结果增加预应力大小、合理布置预应力杆位置、增加预应力杆数量能够增加空间桁架天线固有频率的改变率。结论合理优化空间桁架天线上预应力杆,可实现对在轨运行的空间桁架天线低阶固有频率实时调整,可为空间桁架天线避振设计提供参考。