空管威胁、差错与意外状态的贝叶斯模型分析研究

为准确理解民航空中交通管理中各类人为差错数据的可靠性和相关性,为安全决策提供量化依据,对空管威胁、差错和意外状态数据进行贝叶斯模型分析。该方法在先验概率基础上,通过研究空中意外状态发生条件下威胁与差错各自发生的后验概率,获得上述3类安全信息的相关性大小排序。针对收集到的625起数据样本进行了研究,结果表明:与空中意外状态的发生相关性最大的3类差错依次为:管制员对机组的通讯差错、信息差错以及管制员对管制员的通讯差错;与空中意外状态的发生相关性最大的3类威胁依次为:程序威胁、相邻单位威胁和空中交通威胁。空管运行单位的安全管控应重点关注管制员/机组间的通讯差错,并针对各种可能出现的威胁预先制定应对程序。     

旅游交通弱势群体景区偏好与可达度研究——以大学生秦岭景区旅游为例

针对交通弱势群体的旅游可达问题,通过RBF插值法对秦岭景区大学生的偏好度与公共交通可达度(PTA)之间的关系进行研究.研究发现:①现实偏好度(AP)和潜在偏好度(PP)的高聚集区和低分散区吻合,而其他区域的差异较大,AP呈阶梯状变化而PP分布均衡；②可达性较高区域中的AP与PP吻合,而在较低区域中差异较大；③邻近中心城镇区域中PP与PTA呈正相关,而远离中心城镇区域中两者的影响不大.因此,提高公共交通可达度有助于实现旅游的民生功能.     

车辆间碰撞交通事故计算机辅助鉴定技术综述

在分析车辆间事故过程的基础上,论述车辆间碰撞交通事故计算机辅助鉴定技术的基本原理,回顾碰撞前后阶段的HVOSM,PHASE4,SIMON等事故再现轨迹模型,概要地阐述CRASH类、动量模型类逆向计算系统以及二维、三维正向模拟类软件的计算原理,并进行分析和评述。研究认为,我国车辆间碰撞交通事故鉴定应将逆向计算与正向模拟相结合,建议通过研究交通事故现场勘查技术和建立车辆、轮胎、路面摩擦特性等基础数据库来提高逆向计算系统初始数据的准确性,从而提高交通事故鉴定的精度。     

黑河草滩庄引水枢纽的泥沙冲淤对生态环境的影响

根据黑河草滩庄引水枢纽闸上游泥沙冲淤情况 ,分析了局部冲刷、泥沙淤积和上下游输沙不平衡等对生态环境的影响 ,提出了改善生态环境的具体工程措施     

WATER DIVERSIONS TO THE NORTH AMERICAN PRAIRIES1

ABSTRACT .The major purpose of existing and proposed diversions of water to the Prairies is for irrigation. Being flat lands adaptable to mechanized agriculture and possessing a good network of rail and highway access, they are well suited for such use. Wheat surpluses, currently a serious problem in Canada, can be expected to melt under world population pressures and conversion of wheat lands to other crops with the advent of irrigation. The water sources envisaged are in the Canadian Arctic watershed with the United States purchasing Canadian water at the boundary. There is an increasing interest in the Canadian Prairie Provinces in regarding water as a commodity and selling some of it to pay for the development required to put the portion retained in Canada to use.     

防止南水北调运河水质被污染的思考

作为南水北调输水明渠的京杭大运河，将成为受水区人民的生命河。因此，对北调的水质如何保证不受其污染，就要对每一个可能产生的污染源采取有效的防治措施。     

河北省国道和省道机动车基于交通流量的尾气排放量估算

河北省各城市均已开展利用机动车保有量等宏观统计数据的城市移动源排放清单编制工作,但尚缺乏对跨省及全省各城市间国省道高时空分辨率的移动源排放清单研究.本研究利用2017年河北省国道、省道日均交通流量监测数据,计算了2017年河北省国道和省道机动车大气污染物排放量.结果表明：2017年河北省国道和省道机动车CO、HC、NO_x、PM_2.5和PM₁₀排放量,与利用宏观统计数据计算得到的全省机动车排放总量相比,分别占27.8%、15.7%、55.6%、58.3%和58.5%.重型货车是国道和省道机动车CO、NO_x、PM_2.5和PM₁₀排放的主要来源.河北省南部国省道的机动车排放量以南部各城市为中心呈网状辐射,东北部沿海地区的排放量主要在沧州-天津-唐山-秦皇岛-承德沿线分布,西北部则主要在保定-张家口-内蒙沿线分布.月均排放量分布情况为1月最高,9月最低;周日均分布情况为周一—周三逐日增加,周四开始回落,周日降至最低;每日小时平均分布呈现明显的双高峰现象,两次高峰分别出现在11：00和18：00左右;最低值出现在凌晨4：00.河北省内,各市国省道机动车污染物排放分担率前3位的依次为保定、沧州和张家口.跨省交通车辆排放的CO、HC、NO_x、PM_2.5、PM₁₀分别占河北省国省道机动车总排放量的48.1%、48.7%、42.9%、41.3%和41.3%,其中天津市出入河北省的车辆排放分担率最高,其次是北京.京津冀应在区域层面建立机动车污染联合防治协调机制,从调整区域货运交通运输结构、推动柴油车污染控制措施升级等方面改善区域环境空气质量.     

胶东半岛湖泊面积对气候变化的响应

湖泊是陆地水圈的重要组成部分,不仅参与自然界水循环,而且具有提供水源、调节洪水、维持生态环境健康等功能,研究湖泊面积的动态变化特征,探讨湖泊面积动态对气候变化的响应对水资源的合理利用及生态环境保护具有重要的现实意义。以胶东半岛为研究区,基于1985—2017年的Landsat遥感影像数据为数据源,提取了胶东半岛近33年的湖泊面积和数量信息,揭示了胶东半岛湖泊水体面积变化特征及其对气候变化的响应关系。结果显示：1985—2017年,胶东半岛湖泊面积和湖泊数量均呈波动减少趋势,分别减少100.02 km²和79个。[0.01, 0.1) km²等级的湖泊面积表现为波动增加趋势,其他等级的湖泊面积均表现为波动减少趋势,≥10 km²等级的湖泊面积下降最明显。胶东半岛湖泊面积与降水呈正相关,显著水平均在0.05以上;湖泊面积与气温呈负相关,未达显著水平。胶东半岛影响湖泊面积突变的降水量阈值为626.9 mm左右。低于626.9 mm,湖泊面积随降水量减少而急剧下降;高于626.9 mm,湖泊面积随降水量增加而稳定增长。“引黄济青”工程对大型湖泊面积变化具有重要影响,且极大地缓解了烟威地区的旱情,对胶东半岛自然生态环境和社会经济的可持续发展发挥了重要作用。     

奎屯市主要交通干线噪声状况与分析

通过对奎屯市6条主要交通干线3年的交通噪声监测与分析，得出各条道路车流量、车型、车速和路况的差异。使交通噪声在空间上差异明显，各交通干道交通负荷不是很重，但二侧噪声污染却比较严重，而且污染水平逐年提高。     

First assessment of the PM<Subscript>10</Subscript> and PM<Subscript>2.5</Subscript> particulate level in the ambient air of belgrade city

INTENTION, GOAL, SCOPE, BACKGROUND: As the strong negative health effect of exposure to the inhalable particulate matter PM10 in the urban environment has been confirmed, the study of the mass concentrations, physico-chemical characteristics, sources, as well as spatial and temporal variation of atmospheric aerosol particles becomes very important. OBJECTIVE: This work is a pilot study to assess the concentration level of ambient suspended particulate matter, with an aerodynamic diameter of less than 10 microm, in the Belgrade central urban area. Average daily concentrations of PM10 and PM2.5 have been measured at three representative points in the city between June 2002 and December 2002. The influence of meteorological parameters on PM10 and PM2.5 concentrations was analyzed, and possible pollution sources were identified. METHODS: Suspended particles were collected on Pure Teflon filters by using a Mini-Vol low-volume air sampler (Airmetrics Co., Inc.; 5 l min(-1) flow rate). Particle mass was determined gravimetrically after 48 h of conditioning in a desiccator, in a Class 100 clean room at the temperature T = 20 degrees C and at about 50% constant relative humidity (RH). RESULTS AND DISCUSSION: Analysis of the PM10 data indicated a marked difference between season without heating--(summer; mean value 56 microg m(-3)) and heating season--(winter; mean value 96 microg m3); 62% of samples exceeded the level of 50 microg m(-3). The impact of meteorological factors on PM concentrations was not immediately apparent, but there was a significant negative correlation with the wind speed. CONCLUSIONS: The PM10 and PM2.5 mass concentrations in the Belgrade urban area had high average values (77 microg m(-3) and 61 microg m(-3)) in comparison with other European cities. The main sources of particulate matter were traffic emission, road dust resuspension, and individual heating emissions. When the air masses are coming from the SW direction, the contribution from the Obrenovac power plants is evident. During days of exceptionally severe pollution, in both summer and winter periods, high production of secondary aerosols occurred, as can be seen from an increase in PM2.5 in respect to PM10 mass concentration. RECOMMENDATION AND OUTLOOK: The results obtained gave us the first impression of the concentration level of particulate matter, with an aerodynamic diameter of less than 10 microm, in the Belgrade ambient air. Due to measured high PM mass concentrations, it is obvious that it would be very difficult to meet the EU standards (EEC 1999) by 2010. It is necessary to continue with PM10 and PM2.5 sampling; and after comprehensive analysis which includes the results of chemical and physical characterization of particles, we will be able to recommend effective control measures in order to improve air quality in Belgrade.