基于多元统计的宁夏典农河水质演替特征探究

宁夏典农河是黄河宁夏段的主要入黄排水沟之一,其水质状况对黄河宁夏-内蒙古段跨省流域水质安全至关重要。选取典农河2011—2020年10个监测点位的16项水质参数,采用综合污染指数(WPI)法,结合相关性分析、主成分分析、聚类分析等分析方法,综合分析该流域水污染特征,并对污染程度进行评估,对污染因子和污染原因进行解析,最终提出管控建议。研究结果表明：2011—2020年,影响典农河水质的主要污染因子为COD_Cr、NH₃-N、TP、TN,对应的年均浓度范围分别为22.3～71.5、0.64～9.09、0.173～0.662、2.89～21.52 mg/L,超标率分别为46%、8%、13%、85%。典农河2011—2020年WPI范围为0.59～1.74,重金属含量一直维持在较低水平。流域TN与TP年均浓度比值范围为20～84,整体呈下降趋势,且各监测点的差异性逐渐减小;BOD₅与COD_Cr浓度比值范围为0.02～0.19,反映出典农河流域水体可生化性较差。各监测断面污染物之间存在较强相关性,其中：流域C...     

宁夏连阴雨气候变化特征分析研究

选取宁夏20个气象站的气象观测资料,运用数理统计法、Lepage检验和小波分析等方法,分析了宁夏全年和汛期(5-9月)连阴雨发生次数的气候变化特征及其突变、周期变化。结果表明:自1990年以后,宁夏全年和汛期连阴雨发生了明显变化,连阴雨发生次数均呈减少的趋势,年际变化和年代际变化特征明显;南部山区连阴雨明显多于北部地区,高发中心位于南部六盘山东麓,六盘山东麓连阴雨多于西麓;连阴雨未发生突变;全年连阴雨存在3～5年的短周期和10年、16～18年左右的长周期;汛期连阴雨存在着4～6年的短周期和12年的长周期。     

地铁车站人员疏散离散时间模型研究

疏散时间对于保证地铁车站这类复杂建筑结构内人群的安全至关重要,本文借鉴群集流动理论建立了用于计算地铁车站人群移动时间的疏散离散时间模型(EDTM),模型中的人群流动系数取值不同于传统计算公式中的常量,依据的是经典的车站人群密度与速度函数关系式。将此模型用于某地铁车站站台层,求解楼梯出口疏散人数与时间的关系,并与Building EXODUS疏散软件的模拟结果以及传统地铁车站疏散时间计算公式的计算结果进行了对比,分析表明,EDTM计算结果与EXODUS疏散模拟结果非常接近,且比传统公式计算更为精确和符合实际情况。该计算模型可以为地铁车站人群疏散时间计算、建筑出口性能化设计,以及地铁车站事故应急预案的制定提供更有效的工具。     

环境气象学中的方向数据统计

在环境气象学中,方向数据具有它的特点,统计与普通的数理统计不同。本文将方向数据统计用于环境科学,用风向玫瑰图直观地表达了风向数据,介绍了平均风向的概念和计算方法及风向标准差的合理计算。最后给出厦门市风向研究实例。     

武器装备典型故障和环境效应统计分析

目的 针对武器装备典型故障环境效应进行统计并分析.方法 以收集到的208个试验故障为研究对象,统计分析近10年来武器装备进行环境试验后产生的各种环境效应,以及环境效应的分类、分布及失效原因等,获取武器装备环境试验失效的统计数据.结果 环境效应引起的故障主要集中在电子元器件和机械件的失效上,且电子元器件的失效所占比例在所...     

REGULATED RIVER MODELING FOR CLIMATE CHANGE IMPACT ASSESSMENT: THE MISSOURI RIVER1

ABSTRACT: The Great Plains of the United States, drained primanly by the Missouri River, are very sensitive to shifts in climate. The six main stem dams on the Missouri River control more than one‐half of the nearly 1.5 million square kilometer basin and can store three times the annual inflow from upstream. The dams are operated by the U.S. Army Corps of Engineers using a Master Manual that describes system priorities and benefits. The complex operational rules were incorporated into the Soil and Water Assessment Tool computer model (SWAT). SWAT is a distributed parameter rainfall‐runoff model capable of simulating the transpiration suppression effects of CO₂ enrichment. The new reservoir algorithms were calibrated using a 25‐year long historic record of basin climate and discharge records. Results demonstrate that it is possible to incorporate the operation of a highly regulated river system into a complex rainfall‐runoff model. The algorithms were then tested using extreme climate scenarios indicative of a prolonged drought, a short drought, and a ten percent increase in basin‐wide precipitation. It is apparent that the rules for operating the reservoirs will likely require modification if, for example, upper‐basin precipitation were to increase only ten percent under changed climate conditions.     

汽车简易工况法与新车排放认证工况法的相关性研究

选取50辆在用轻型汽油车,对国家标准规定的瞬态工况法(IM195)、简易瞬态工况法(IG195)、稳态工况法(ASM)与新车排放认证工况法(NEDC)间污染物排放系数的相关性进行研究.结果表明:瞬态工况法与新车排放认证工况法的污染物排放系数相关性最好,CO,碳氢化合物(HC)和NO的排放系数的R〖WTBZ〗2分别为0.701 0,0.727 1和0.6609;简易瞬态工况法次之,其CO,HC和NO 排放系数与新车排放认证工况法的R2分别为0.513 8,0.484 6和0.624 5;而稳态工况法与新车排放认证工况法的相关性最差,5025工况法下的CO,HC和NO 排放系数与新车排放认证工况法的R〖WTBZ〗2分别为0.410 9,0.448 1和0.5449;2540工况法下R〖WTBZ〗2分别仅为0.364 4,0.339 5和0.457 8.引起不同方法间污染物排放系数相关性差异的主要原因包括车辆热状态、车辆试验循环工况、分析仪器的测量原理和底盘测功机的控制精度等.      

Forecasting the Probability of Future Groundwater Levels Declining Below Specified Low Thresholds in the Conterminous U.S.

We present a logistic regression approach for forecasting the probability of future groundwater levels declining or maintaining below specific groundwater‐level thresholds. We tested our approach on 102 groundwater wells in different climatic regions and aquifers of the United States that are part of the U.S. Geological Survey Groundwater Climate Response Network. We evaluated the importance of current groundwater levels, precipitation, streamflow, seasonal variability, Palmer Drought Severity Index, and atmosphere/ocean indices for developing the logistic regression equations. Several diagnostics of model fit were used to evaluate the regression equations, including testing of autocorrelation of residuals, goodness‐of‐fit metrics, and bootstrap validation testing. The probabilistic predictions were most successful at wells with high persistence (low month‐to‐month variability) in their groundwater records and at wells where the groundwater level remained below the defined low threshold for sustained periods (generally three months or longer). The model fit was weakest at wells with strong seasonal variability in levels and with shorter duration low‐threshold events. We identified challenges in deriving probabilistic‐forecasting models and possible approaches for addressing those challenges.     

A Prospective Biomonitoring Campaign with Honey Bees in a District of Upper-Bavaria (Germany)

In order to establish a monitoring method to track long term changes of the amount of anthropogenic contamination in a district of Bavaria (Germany), a biomonitoring campaign with honey bees was performed in spring 2002. Expected anomalies from the industry or from residential areas in the sampled district could not be detected. An anomaly over a considerable part of the sampling area correlating with other phenomena lead to the hypothesis of a prehistoric cosmic impact. Moreover a principal component analysis of the data showed evidence for a biogenic, an anthropogenic and an unknown component hypothetically related to a possible cosmic impact.