污染物总量控制空间动态管理初探

基于不同区域的环境要求,可将一个地区污染物总量控制分为禁止开发区、限制开发区和普通区.本文建立了普通区污染物总量控制目标值及变化值的计算方法,并将此方法具体应用到某市的污染物空间总量动态控制管理研究中.通过选取最佳分配方案,从而达到"经济发展最好、环境质量最优"的效果.     

喀斯特地区城市绿地土壤呼吸对降水变化的响应研究

降水是影响土壤呼吸一个重要的影响因子,研究降水对土壤呼吸的影响,对估计和预测陆地生态系统土壤呼吸变化有着重要的意义,但目前自然降水对喀斯特地区城市绿地土壤呼吸影响的研究目前还鲜有报道.本研究利用静态暗箱法,对降水后贵阳城市绿地土壤呼吸速率变化进行了24 h定位监测,对比研究了不同强度降水后土壤呼吸速率变化,并分析了水热...     

Experimental and numerical study of CO2 plume diffusion in a confined space

In this paper, heavy gas diffusion in a confined space has been investigated. The effects of barrier and source intensity on CO₂ diffusion are explored by the small-scale experiments and computational fluid dynamics (CFD) methods. Six different turbulence models are selected to predict the gas concentrations. By comparing these experimental values with the simulated ones, it is found that all models can effectively predict the concentration variation with time, and SST k-ω model is most close to the ideal model compared with others. Three source-barrier distances and three CO₂ flow rates have been set up for the study. In this confined space, the main flow is concentrated in the region near the ground. The existence of barriers in the space will have a dilution effect on the high-concentration plume near the ground of the near-source area and a barrier effect on the low-concentration plume in the far-source area. The changes in source intensity have notable impact on the gas concentrations. This study can provide an experimental basis for the risk assessment in the confined spaces, as well as an experimental and data reference for large-scale CFD simulations.     

Numerical investigation and analysis of indoor gas explosion: A case study of “6·13” major gas explosion accident in Hubei Province,China

Taking the ' 6·13 ′ major gas explosion accident in Shiyan, Hubei Province, China as an example, three problems were studied in this work: (1)The determination of the volume of natural gas involved in the explosion; (2)The propagation process of shock wave inside the building and the damage evolution process of the accident-related building; (3)The overpressure and fragment injury to the person outside the building. Through the numerical simulation in ANSYS/LS-DYNA software, the volume of natural gas involved in the explosion is determined to be 10240 × 1400 × 400 cm (length × width × height) from three perspectives: the damage to the building, the distribution of overpressure inside the building, and the TNT equivalent of the explosion energy. The simulation results are in good line with the accident, which verifies the effectiveness of the scheme and the accuracy of the numerical model. Based on the reasonable filling scheme, the propagation process of shock waves inside the building, the damage evolution process of the building, and the injury ranges of overpressure and fragments outside the building are analyzed. It can be found that the propagation of shock waves in confined space is complex and variable. The explosion shock waves are first reflected and superimposed in the watercourse, resulting in pressure rise. At about 8ms, the shock waves rushed into the first-floor space of the building, and the maximum overpressure was about 0.56 MPa. At about 50 ms, the shock waves rushed into the second-floor space, and the maximum overpressure was about 0.139 MPa. The first and second-floor slabs and infilled walls were almost completely destroyed. The interior walls of the infilled walls are mainly collapsed, and the exterior walls are ejection around the building as the center. The peak displacement and peak velocity of the interior walls of each floor are about 15% of the exterior walls. The fragments which cause fragment injury mainly come from the retaining wall above the watercourse, the maximum velocity is about 89 m/s, and the maximum displacement is 8.9 m. The safety distance of fragment injury is about 8.8 m, while the safety distance of overpressure injury is about 4.6 m. The lethal distance of fragment injury is greater than that of overpressure injury. Compared with the distance between different damage levels of overpressure injury, the difference in fragment injury is small. Therefore, the safety assessment at the engineering level only needs to consider the safety distance of fragment injury. This study can provide suggestions for evaluating the damage of natural gas cloud explosions in confined spaces and is helpful for accident investigation and safety protection.     

受限空间作业的风险分析与控制

受限空间作业涉及的行业多、危险因素多,发生事故时救援难度大且后果严重。本文在对受限空间作业风险进行分析的基础上,从安全管理、作业过程、作业环境三个方面提出了相应的风险控制措施和建议。该研究对有效控制受限空间作业的风险以及预防事故的发生具有重要的意义。     

临近空间环境及环境试验

从热力学结构、大气成分特征、大气电磁特性等方面介绍了临近空间环境参数,按照临近空间飞行器的平均密度、飞行速度、飞行高度介绍了临近空间飞行器的分类及特点。阐述了临近空间环境试验的方法,并对临近空间环境试验技术的发展提出了初步建议。     

风险规避、非牧用途使用与牧户草原流转行为

基于新疆12个牧业县232户微观数据,运用风险收益理论、期望效应理论构建了草原流转风险规避理论模型与基于博弈论构建了草原流转非牧用途使用理论模型,分析了风险规避和非牧用途使用对牧户草原流转的内在机理。使用二元Logit模型、中介效应与调节效应分别探析风险规避和非牧用途使用对牧户流转行为的影响。研究表明：违约风险、生态风险、经营风险对牧户草原流转行为存在显著影响,草原流转存在的各类风险可能导致牧户的风险规避行为;非牧用途使用、转移就业能力担忧与家庭收入结构对于牧户草原流转行为存在显著影响;家庭收入结构在牧户面临非牧用途使用时存在调节效应,而其转移就业能力担忧在牧户面临非牧用途使用时存在遮蔽效应。同时,违约风险、生态风险在牧户面临非牧用途使用时存在中介效应。在此基础上,进一步讨论了造成流转风险、非牧用途使用问题的成因与对策。     

碳中和目标下的国土空间格局优化：理论框架与实践策略

国土空间规划是在基础层面引导土地利用、生态保护、产业布局、城乡建设和区域开发的国家基础性、约束性规划。在当前“双碳”战略背景下,将碳中和目标纳入国土空间规划和治理体系,对于从基础层面推动经济社会系统全面低碳转型具有重要意义。本文构建了碳中和目标下国土空间格局优化的理论框架,分析了国土空间格局、人地关系与碳收支的内在关系。从“经济—社会—生态”复合系统的视角探讨了碳中和目标下国土空间格局优化和调控机理;从国土空间碳收支核算体系、面向碳平衡的“双评价”方法、国土空间碳风险监测与评价、碳排放空间约束下的三线划定、碳达峰与产业空间结构调控等方面提出了面向碳中和的国土空间格局优化路径;从差别化的生态碳汇提升方案、符合中国国情的国土空间碳收支核算体系、面向碳中和目标的国土空间规划管控方案、基于生命周期的建设用地碳排放评估、低碳高效的国土空间治理体系、多层次国土空间碳补偿体系构建等方面,提出了碳中和目标下国土空间格局优化的关键领域。     

基于多点关联性的尾矿坝位移监测序列异常值诊断*

针对尾矿坝位移监测序列中噪声和真实异常值的区分问题,提出1种基于多点关联性和改进孤立森林（IF）算法的异常数据诊断模型。通过IF算法对监测序列中的各样本点异常程度进行量化计算,引入云模型（CM）算法确定IF量化的异常得分与异常概念的相互映射关系以实现异常点的初步诊断,根据Apriori算法计算多测点序列间的关联性,找出强关联序列组合,结合序列关联性以及异常点诊断结果区分噪声与真实异常值。以某尾矿坝位移监测序列为例进行模型验证。研究结果表明:基于多点关联性的异常诊断模型能够有效区分尾矿坝位移监测序列中的噪声与真实异常值,提高监测系统的准确性。     

高温独头巷道人工制冷降温效果的优化研究*

为优化移动式人工制冷设备在高温独头掘进巷道工作面的制冷效果,通过设置风障形成密闭制冷空间,利用数值计算的方法,分别分析风障距工作面距离、回风管压力、回风管垂直高度对掘进工作面制冷效果的影响。研究结果表明:设置风障能够有效缩小制冷空间,阻隔热量,提高制冷效果;风障与工作面之间的距离对制冷效果有显著影响,风障的最佳布置距离为5 m;回风口压力过大或过小都不利于制冷效果,最佳压力为-70 Pa;回风管垂直高度不同,制冷效果也大有不同,其最佳高度为1 m。利用数值模拟所得工况参数进行现场试验,结果表明风障在高温独头掘进巷道降温中具有良好的实际应用效果。研究结果对高温矿井人工制冷工况优化,提高制冷效果具有指导意义。