The response statistics of a compliant offshore structure excited by slowly varying wave drift forces is calculated by use of a numerical path integral solution method. The path integral solution is based on the Ganss...The response statistics of a compliant offshore structure excited by slowly varying wave drift forces is calculated by use of a numerical path integral solution method. The path integral solution is based on the Ganss-Legendre interpolation scheme, and the values of the response probability density are obtained at the Gauss quadrature points in sub-intervals. It is demonstrated that a distinct advantage of the path integral solution is that the joint probability density of the response displacement and velocity is one of the by products of the calculations. This makes it possible to calculate the mean level up-crossing rates, which provides estimates of the exceedance probabilities of specified response levels for given time periods.展开更多
近年来,随着我国大气污染防控政策和措施的实施,SO_(2)等污染物的年均浓度降低显著,但日均或小时浓度超标问题依然存在。通过分析A市2019—2023年的SO_(2)监测数据,发现该地区的SO_(2)年均浓度已符合国家环境空气质量二级标准限值,但小...近年来,随着我国大气污染防控政策和措施的实施,SO_(2)等污染物的年均浓度降低显著,但日均或小时浓度超标问题依然存在。通过分析A市2019—2023年的SO_(2)监测数据,发现该地区的SO_(2)年均浓度已符合国家环境空气质量二级标准限值,但小时浓度超标倍数在0.002~1.236。针对这一问题,基于2022年高分辨率污染源排放清单(High-resolution Emission Inventory,HEI-A2022),利用空气质量模式——耦合化学机理的气象研究和预测模型(Weather Research and Forecasting Model with Chemistry,WRF-Chem)进行模拟研究,结果显示:导致SO_(2)小时浓度频繁超标的主要原因是有色金属冶炼企业在生产过程中的瞬时高负荷排放,这使得SO_(2)有组织和无组织排放量呈现出明显的波动特征。即使全年总排放量符合排污许可规定的许可排放量,但无法有效控制短时间内出现的超标情况。为此,研究利用空气监测站点处污染物浓度对污染源排放的响应关系,构建了一套以改善空气质量为目标的大气污染源小时排污许可排放量核算方法,解决了城市或区域小时或日均值超标的问题。以控制A市SO_(2)小时浓度超标为例,得到A、B、C冶炼公司及其他企业的小时许可排放量分别为130.4 kg/h、53.4 kg/h、50.6 kg/h和58.1 kg/h,A市工业园区SO_(2)小时许可排放量为292.51 kg/h。研究以每小时的许可排放量作为管控目标值对污染源排放的精准管控,能够有效地解决当前存在的小时浓度超标问题,还为其他面临类似问题的城市和地区提供了解决此类问题的新思路。展开更多
文摘The response statistics of a compliant offshore structure excited by slowly varying wave drift forces is calculated by use of a numerical path integral solution method. The path integral solution is based on the Ganss-Legendre interpolation scheme, and the values of the response probability density are obtained at the Gauss quadrature points in sub-intervals. It is demonstrated that a distinct advantage of the path integral solution is that the joint probability density of the response displacement and velocity is one of the by products of the calculations. This makes it possible to calculate the mean level up-crossing rates, which provides estimates of the exceedance probabilities of specified response levels for given time periods.
文摘近年来,随着我国大气污染防控政策和措施的实施,SO_(2)等污染物的年均浓度降低显著,但日均或小时浓度超标问题依然存在。通过分析A市2019—2023年的SO_(2)监测数据,发现该地区的SO_(2)年均浓度已符合国家环境空气质量二级标准限值,但小时浓度超标倍数在0.002~1.236。针对这一问题,基于2022年高分辨率污染源排放清单(High-resolution Emission Inventory,HEI-A2022),利用空气质量模式——耦合化学机理的气象研究和预测模型(Weather Research and Forecasting Model with Chemistry,WRF-Chem)进行模拟研究,结果显示:导致SO_(2)小时浓度频繁超标的主要原因是有色金属冶炼企业在生产过程中的瞬时高负荷排放,这使得SO_(2)有组织和无组织排放量呈现出明显的波动特征。即使全年总排放量符合排污许可规定的许可排放量,但无法有效控制短时间内出现的超标情况。为此,研究利用空气监测站点处污染物浓度对污染源排放的响应关系,构建了一套以改善空气质量为目标的大气污染源小时排污许可排放量核算方法,解决了城市或区域小时或日均值超标的问题。以控制A市SO_(2)小时浓度超标为例,得到A、B、C冶炼公司及其他企业的小时许可排放量分别为130.4 kg/h、53.4 kg/h、50.6 kg/h和58.1 kg/h,A市工业园区SO_(2)小时许可排放量为292.51 kg/h。研究以每小时的许可排放量作为管控目标值对污染源排放的精准管控,能够有效地解决当前存在的小时浓度超标问题,还为其他面临类似问题的城市和地区提供了解决此类问题的新思路。
