Influence of Rainfall Run-off in Hydrologic Process on Non-Point Pollution

[Objective] This study aimed to study on influence of rainfall runoff on non-point pollution and to reduce the pollution through control of the contamination produced from rainfall runoff. [Method] In order to explore effective methods to decrease non-point pollution, we conducted analysis on hydrological process of rainfall runoff, interaction mechanism between the process and non-point pollutants, the influence on non-point pollution and hydrological model application in the research. [Result] It was proved that rainfall runoff was the main factor of non-point pollution. Control from source strengthened clearing and controlling of non-point pollutants on the ground. Growing plants in slope effectively reduced the scour and erosion of rainfall runoff on soil. The study became simple thanks for the hydrological process. [Conclusion] The research indicated that non-point pollution would be effectively reduced through control of rainfall runoff.

QUANTITATIVE STUDY OF SOIL EROSION AND ELEMENT RUN-OFF IN THE SONGHUA LAKE VALLEY

Under the condition of different precipitation intensities, different gradients, different land-use types and different vegetation coverage, the soil erosion and transference of element (or pollutant) are studied by simulating and analyzing the surface run-off of experimental plots in the catchment area of Songhua Lake, with an area of about 43 370.8km2. And the influencing factors that produce the spatial difference are analyzed and assessed. It is put forward that the irrational land utilization is the reason of soil erosion and pollutant run-off. The gradient of farmland, the growing season of vegetation and the vegetation coverage are chiefly restricting factors that lead to the soil erosion and pollutant run-off. This study can provide the fundamental data for comprehensive planning and harnessing of the non-point source pollution in the valley.

Crash Severity Analysis of Single Vehicle Run-off-Road Crashes

Run-off-road crashes in the United States have become a major cause of serious injuries and fatalities. A significant portion of run-off-road crashes are single vehicle crashes that occur due to collisions with fixed objects and overturning. These crashes typically tend to be more severe than other types of crashes. Single vehicle run-off-road crashes that occurred between 2004 and 2008 were extracted from Kansas Accident Reporting System (KARS) database to identify the important factors that affected their severity. Different driver, vehicle, road, crash, and environment related factors that influence crash severity are identified by using binary logit models. Three models were developed to take different levels of crash severity as the response variables. The first model taking fatal or incapacitating crashes as the response variable seems to better fit the data than the other two developed models. The variables that were found to increase the probability of run-off-road crash severity are driver related factors such as driver ejection, being an older driver, alcohol involvement, license state, driver being at fault, medical condition of the driver;road related factors such as speed, asphalt road surface, dry road condition;time related factors such as crashes occurring between 6 pm and midnight;environment related factors such as daylight;vehicle related factors such as being an SUV, motorcycles, vehicle getting destroyed or disabled, vehicle maneuver being straight or passing;and fixed object types such as trees and ditches.

新型动力轻型飞机飞行性能仿真评估

为评估新型动力轻型飞机的飞行安全性,基于民用航空器适航审定理念和方法,选取飞行关键的阶段,应用MATLAB软件模拟该型飞机起飞地面滑跑和起飞爬升性能,计算滑跑距离和爬升率。结果表明混合动力型轻型飞机的起飞地面滑跑距离缩短了10%,爬升性能提高了22%,同时混合动力型飞机对起飞机场的高度和温度环境适应能力也明显提升。该方法可作为混合动力轻型飞机适航审定中验证符合中国民航CCAR-23-R4规章第23.2115条款“起飞性能”和第23.2120条款“爬升”要求的一种方法。

LUCC and its impact on run-off yield in the Bai River catchment—upstream of the Miyun Reservoir basin

Aims The Miyun Reservoir is the most important drinking water source for Beijing—the capital of China with a population of more than 16 million.Since the 1980s,the inflow to the reservoir has been decreasing,which seriously threatens the security of water use in Beijing.Our goal was to analyze the impact of land use and cover change(LUCC)on run-off yield in the upstream of the Miyun Reservoir.Methods In this study,the Soil andWater Assessment Tool(SWAT)was used to simulate the impacts of LUCC on the run-off yield in the Bai River catchment—upstream of the Miyun Reservoir basin in northern China.The investigation was conducted using two 6-year historical streamflow records:from 1986 to 1991 and from 2000 to 2005.A split sample procedure was used for model calibration and validation.The data from 1986 to 1988 and from 2000 to 2002 were used for calibration,while those from 1989 to 1991 and from 2003 to 2005 for validation.The SWAT calibration was based on monthly measured discharge at Zhangjiafen station at the catchment outlet from Bai River catchment.Additionally,the influence of LUCC on the surface run-off was distinguished from that of climate change on the surface runoff through SWAT scenarios modeling,the twoway analysis of variance(ANOVA),and the rainfall–run-off double-mass analysis in the Bai River catchment.Important Findings We found that the SWAT model could be used successfully to accurately simulate run-off yield and different LUCC patterns affecting water quantity in this catchment.During calibraion for the two periods the simulated monthly run-off satisfactorily matched the observed values,with the Nash–Sutcliffe coefficient>0.9 and 0.7 and a coefficient of determination of 0.9 and 0.65 at the outlet station(Zhangjiafen station),while during validation for the two periods the obtained values were 0.85,0.65 and 0.9,0.65,respectively.During the period of 1986–91,both the SWAT scenarios modeling and the analysis of the two-way ANOVA method showed that LUCC and climate change had some impact on run-off,and the impact of climate change was more significant than that of LUCC.Compared with the period during 1986–91,the run-off yield in the period during 2000–05 significantly decreased.The obtained results from the rainfall–run-off double-mass analysis indicate that since 1998 LUCC has had an increasing influence on the run-off,while the response of the run-off to rainfall has been decreasing.Since 1998,the LUCC has been a major driving force for run-off change in Bai River catchment.

干撒PAM对黄绵土工程堆积体侵蚀泥沙的影响

为了探寻PAM(聚丙烯酰胺)的适宜干撒量,以减少工程堆积体的侵蚀泥沙和维持工程堆积体的稳定性,在黄土丘陵沟壑区,以不撒PAM(聚丙烯酰胺)为对照(CK),将0.5、1.0、1.5、2.0、2.5 g/m^(2)的PAM干撒于圆锥状黄绵土工程堆积体的表层,监测自然降雨状况下PAM对黄绵土工程堆积体的地表径流、侵蚀泥沙、细沟发育和堆积体土壤水分含量等的影响。结果表明:不同处理的径流量、产流次数和径流系数均随PAM干撒量的增加表现为先降低后升高,其中干撒量为1.0 g/m^(2)的最低,2.5 g/m^(2)的最高。侵蚀泥沙量、细沟侵蚀量和细沟侵蚀系数则随PAM干撒量的增加而降低,其中干撒量为1.5、2.0、2.5 g/m^(2)的显著低于CK、0.5、1.0 g/m^(2)。当PAM干撒量为1.0 g/m^(2)时,工程堆积体的土壤水分含量最高,当PAM干撒量为2.5 g/m^(2)时则最低。PAM干撒量达到1.5 g/m^(2)可促进径流形成,减少侵蚀泥沙量及细沟侵蚀系数,降低黄绵土堆积体的土壤水分含量。为了减少侵蚀泥沙量,维持黄绵土工程堆积体的稳定性,PAM的干撒量应为2.0 g/m^(2)左右。

Characteristics and sources of polycyclic aromatic hydrocarbons in impervious surface run-off in an urban area in Shanghai, China

Rainwater and run-off from three kinds of impervious surface in the Shanghai urban area,China were sampled.Polycyclic aromatic hydrocarbons(PAHs) were measured in the samples,and their sources were assessed.The mean sum of the 16 PAH concentrations measured in rainwater and run-offs from ceramic tiles,asphalt roofs,and asphalt roads were 873,1404,1743,and 4023 ng/L,respectively.The PAH concentrations found in this study were moderate compared to PAH concentrations found in run-offs in other studies.The main PAH components in the rainwater,roof run-off,and asphalt road run-off samples were 3-ring PAHs,3–4-ring PAHs,and 4–6-ring PAHs,respectively.Source apportionment results indicated that combustion(47.4%–55.5%) and vehicular emissions(30.5%–33.0%) were the major contributors to PAHs in roof run-off.Vehicular emissions were the most significant contributors to asphalt road run-off(47.2%),followed by combustion(23.5%),and petroleum(16.3%).Vehicular emissions and coal and natural gas combustion are therefore the most significant sources of PAHs in run-off from impervious surfaces in the Shanghai urban area.

变入口压力下大容量压缩空气储能电站空气透平动态过程及调节特性研究

压缩空气储能系统的空气透平入口压力变化较大,为了掌握该条件下透平的特性及规律,使用多学科仿真平台MSP和模块化建模工具PowerBuilder搭建了全工艺流程的300MW级压缩空气储能系统,分析空气透平在入口压力大幅变化情况下的运行特性和调节过程,揭示储气室压力大幅变化下透平膨胀比、出口温度和效率等关键参数的变化规律,确定了透平的功率调节过程及响应特性,并分析了透平入口温度对机组功率的影响和限制,为大容量压缩空气储能系统空气透平的运行和调节提供了数据支撑和科学依据。

矿用防跑偏立辊壳焊接工装的设计

防跑偏立辊壳是矿用皮带机的调偏装置,传统生产工艺是手工组对和焊接,焊接后壳体和挡环的端面平行度较差,并且生产效率较低。为了提高产品质量和生产效率,设计了矿用防跑偏立辊壳焊接工装,包括组对定位工装和焊接辅助工装。对组对定位工装和焊接辅助工装进行了分析,对现场安装使用进行了介绍。应用矿用防跑偏立辊壳焊接工装,可以提高生产效率,降低劳动强度。

降低竖炉带冷机故障及提升冷却效率的措施

新疆昕昊达矿业有限责任公司采用球团竖炉工艺,用带式冷却机对球团矿进行冷却,在生产运行中带冷机故障频繁,经常性非计划停机,设备作业率低,影响竖炉产能的发挥。带冷机主要存在轨道跑偏、漏料严重和小刮板掉道等问题。同时,因原篦子箅缝中卡球团,导致冷却效率降低。利用年修及定期检修对带冷机进行技术改造后,故障发生率降低了90%以上,冷却效率大幅提高。

带式输送机的跑偏与调整典型案例分析

阐述了选煤厂主要的运输设备带式输送机在运行过程中会因为各种原因出现胶带跑偏的现象,从而出现胶带撒煤、胶带折叠、撕胶带等问题。以下平行调心托辊的调偏原理对胶带在重锤滚筒、机尾滚筒、改向滚筒等几个位置跑偏进行调偏,解决因滚筒换向干扰而不能正确调偏的问题。

世界优秀男子跳远运动员助跑与起跳技术运动生物力学分析——以2017年伦敦世界田径锦标赛为例

世界优秀跳远运动员后三步基本都呈现出“中-大-小”的变化趋势,助跑速度与跳远成绩呈高度相关性。世界优秀跳远运动员腾起角度呈增大趋势;离板瞬间运动员身体重心与垂直面夹角过大或过小都会影响运动员速度能力的发挥。着板瞬间膝关节角度、最大缓冲时刻膝关节角度和膝关节角度呈现出不同的技术特点,由于精英运动员技术风格和动作节奏不同,膝关节角度变化较大,垂直分速度较小,但下压扒地积极,技术动作的转换速度较快,对成绩影响较小;水平较差的运动员离板瞬间水平速度较小,缓冲时间较长,肌肉拉伸过度或不足,造成垂直分速度增加,向前性不足,影响比赛成绩。

一种便携式轮对不圆度的设计与研究

随着铁路列车运行速度的提高,铁路车辆和轨道之间相互作用力逐渐增强,使得车轮踏面失圆的问题不容小觑。对此研发了一款轨道车辆轮对不圆度检测仪。使用钕铁硼磁力开关,将设备吸附在钢轨上,待测轮对旋转带动金属滚轮使旋转编码器工作,自复位高精度电子尺持续采集轮对踏面径跳信息,霍尔感应开关判断轮对旋转一周后自动锁死,嵌入式微处理器经过计算后将轮对径跳、平均直径等信息显示在MCGS组态显示屏上,为车轮镟修提供参考。

高校足球课程中无球跑动意识的教学研究

无球跑动意识能够有效提高球员的进攻能力和团队协作能力,有助于提高球员的综合素质,帮助球队赢得比赛。无球跑动意识教学能够提高大学生球员的比赛阅读能力。在比赛中,球员需要不断观察和分析场上形势,判断对方的战术意图和弱点,制定出应对策略。通过加强无球跑动意识教学,大学生球员可以形成敏锐的观察力和判断力,提高自己在比赛中的应变能力和决策水平。目前,大学生在参与足球运动时缺乏无球跑动意识,高校的足球无球跑动意识教学还需要进一步完善。因此,该文就高校足球课程中无球跑动意识教学展开研究,通过了解现阶段大学生无球跑动意识与教学现状,分析存在的问题,讨论相应的提升措施。

某离网海岛民宿区风光储系统方案设计

本文研究了离网海岛风光储系统方案设计方法,并选取典型年数据,结合海岛旅游淡旺季负荷特性进行了系统运行模拟和容量规划。结果表明,采取风光储供电系统可部分替代原有燃气发电系统,整体方案具有一定经济性,可应用于同类型离网海岛,以及季节负荷波动较大区域的风光储系统方案设计中。

基于物质流模型的长三角城市群食物生产与消费系统氮素流动格局及影响因素

作为区域社会经济发展的重要增长极,城市群食物生产与消费系统活性氮的释放对区域氮素循环格局有着重要影响。采用物质流分析模型,定量分析2019年长三角城市群农田种植、畜禽养殖、水产养殖和人类消费子系统的氮素流动格局,评估各子系统氮素损失的结构,阐明氮素损失的空间分布,并探究氮素损失强度的主要影响因素。结果表明,系统总体氮输入为3472.56 Gg/a,最大氮素输入项为化肥输入;系统总体氮输出为3061.29 Gg/a,主要表现为氮素损失,占90.9%。农田种植、畜禽养殖和水产养殖子系统的氮素利用效率分别为42.6%、30.8%和40.1%。农田种植子系统对系统氮素损失的贡献最大,为1325.53 Gg/a,占比为47.6%;其后依次为人类消费子系统、畜禽养殖子系统和水产养殖子系统。长三角各城市氮素损失强度空间异质性较大,上海、扬州、盐城较高,分别为26.43、23.20和22.26 kg/hm^(2);杭州、宣城、池州较低,分别为6.14、5.83和4.55 kg/hm^(2)。氮素损失强度空间异质性与经济、人口、农业生产和土地利用等因素的相关性具有统计学意义(P<0.05或0.01),相关系数为0.42~0.76。

动作姿态对北欧两项运动员跳台滑雪助滑和起跳气动阻力的影响

目的:探讨北欧两项运动员不同助滑和起跳动作姿态产生原因其对气动阻力的影响及机理,并将姿态参数对气动阻力的影响进行量化评估。方法:以5名北欧两项国家队运动员为对象,采用风洞测试和高清摄像系统及视频分析系统对其在风洞水平工作段中进行助滑和起跳训练时身体姿态和关节角度参数、气动阻力参数进行采集和分析,通过运动员身体形态、运动学特征等因素分析不同姿态产生的原因,探究其影响助滑起跳姿态的机理。结果:1)同一运动员在保持头部平视(与铅垂线夹角θ_(1)=90.4°)、躯干水平(与水平面夹角θ_(2)=0°)、手部水平伸展、完全蹲踞式(髋关节角度θ_(3)=37.6°)姿态进行助滑时气动阻力最小,具有最佳减阻效果。2)不同运动员的起跳动作中,“膝动带髋式”姿势为最佳减阻姿势,相对于平均气动阻力最大的“髋膝变速同步式”姿势,减阻率达到18.34%。3)皮尔逊相关分析表明,运动员的右侧髋关节内外旋ROM增加,起跳的气动阻力相应减小;右髋屈ROM增加,气动阻力相应会增大,起跳气动阻力的降低,有利于运动员赛季跳台的平均距离的提高,以上3组变量之间相关性均具有显著水平(P<0.05)。结论:不同助滑和起跳姿态下北欧两项运动员的气动减阻效应存在一定差异,影响助滑和起跳气动减阻的因素有运动员专项技术特点、身体形态和运动功能特征、心理和场地环境因素等。研究不同姿态的气动减阻效应能够为运动员减小空气阻力、优化能量分配、改进训练策略、提升竞技表现提供重要的科学指导。

连通试验在西南某区岩溶地下水污染溯源中的应用

为查明岩溶地下水径流特征及连通性现状,验证西南某潜在污染区突发岩溶地下水污染与养殖排废的关系,开展连通试验。试验结果表明:荧光素钠在峰值期的平均浓度是稳定期的119倍,养殖排废区开挖的落水洞与岩溶下降泉之间存在直接水力关系,地下水径流速度约为3.0×10^(-3) m·s^(-1),流速低,总体自东南向西北径流;径流通道形态单一,连通性好。

城市生态公园水系建设防洪影响评价分析研究

新建城市生态公园水系,若与现状河道相连通,会对河道行洪及河势稳定产生一定影响。基于GIS水文分析模型,采用MIKE11、MIKE21水动力模型,构建研究区域的产汇流模型、河道一维水动力模型、生态公园水系二维水动力模型。通过模型分析,计算河道不同来水频率下的设计洪水过程及生态公园水系建设区域的淹没范围,对河道行洪安全、河势稳定、公园建设项目、堤防及其他水利工程设施等进行防洪影响评价,提出相应的防治措施,为城市生态公园水系的建设提供支撑。

电动助力转向PDC功能跑偏补偿原理及测试分析

车辆行驶跑偏问题一种常见的影响车辆使用性能的失效模式,文章根据车辆行驶跑偏特性,提出拉拽补偿(PDC)功能场景识别、补偿扭矩计算及PDC补偿扭矩输出三个阶段,并将跑偏考核指标偏移时间(TTD)和保舵力(TTT)纳入PDC功能验收性能指标。阐述并论证PDC功能对跑偏问题优化的贡献,具有一定的工程应用价值。