大连地区能见度特征分析

大连市大气能见度逐年下降,灰霾现象严重,收集大连市2011—2013年大气能见度及同期地面气象要素（风速、温度、气压和相对湿度）观测资料监测数据,探讨大连市大气能见度的特征及大气能见度与气象要素和空气污染之间的关系。统计分析结果表明,大连市大气能见度的年、季、日变化特征明显,呈明显的逐年下降趋势。     

近50年四川能见度变化特征及影响因素

应用四川省147个气象观测站1961—2010年能见度、湿度、降水、风速和温度等资料,以海拔750 m为界分为盆地和非盆地站点,在排除湿度、降水、大风等天气现象的条件下,分析能见度的时空分布特征及其影响因素。结果表明:四川盆地及周边地区能见度较低,在15³0 km之间,且其能见度呈减小趋势,西部人烟稀少、畜牧业为主的高海拔山区的能见度较好,平均为4030 km之间,且其能见度呈减小趋势,西部人烟稀少、畜牧业为主的高海拔山区的能见度较好,平均为40⁵0 km,并呈增大趋势;盆地大部分地区的年平均风速是减小的,川西高原大部分地区年平均风速都是增大的,除了川北少部分地区,其他地区年平均温度逐年升高;影响四川能见度的主要因素除了排放增加、特有的盆地地形和海拔外,还与风速、温度变化有关。     

预湿轻集料对混凝土内部相对湿度特性的影响

为缓解混凝土的早期自干燥,减小自收缩,用预湿轻集料对其内部相对湿度进行调控.采用湿度测试仪和混凝土收缩测试仪,研究了水胶比、矿物掺合料对混凝土内部相对湿度与自收缩的影响规律,及预湿轻集料对自收缩的抑制效果.研究表明:混凝土内部相对湿度早期下降快,后期下降慢;降低水胶比、掺加硅灰会加快内部相对湿度的下降速度,而粉煤灰的加入可延缓低水胶比混凝土早期内部相对湿度的下降过程.预湿轻集料的引入可对混凝土内部相对湿度起到补偿作用,减小自收缩,作用效果随轻集料引入水量的增大而增强.     

大气腐蚀环境对四川电网输变电设备腐蚀的影响研究

主要对造成金属腐蚀的气象因素和大气污染物进行归纳分析,试图为四川地区电网防腐蚀后续工作提供一定的理论指导。其中气象要素包含相对湿度、表面润湿时间、降雨和温度;污染因子主要为SO2,氮氧化物、Cl-及其他气体、固体颗粒物等。同时针对四川地区具体气候条件和环境情况,分析指出:相对湿度和SO2是影响四川地区大气腐蚀最主要的因素,大气相对湿度增大导致金属表面容易形成薄液膜,提供了大气污染物与金属发生腐蚀反应的有利条件,从而加速金属的腐蚀破坏。     

福州长乐国际机场能见度的特征分析

本文利用1998年至2007年民航福州长乐国际机场地面气象观测资料对福州长乐国际机场的能见度的年,日变化做出分析。分析表明机场累年平均上半年能见度小于1000米日数明显多于下半年,占全年的83％,机场能见度有明显的季差异,表现为春季能见度最差,冬季次之,夏、秋季能见度最好,机场各季以后半夜18—22时段能见度最低,之后能见度逐时上升,午后06—08时段能见度达到最高,傍晚以后又逐渐下降,春季是福州机场雾日最多的季节,多为在冷锋过境前,锋前暖区回暧,晴朗夜空,早晨降温增湿而引起的锋前辐射雾,以及海上平流雾,有时二者相结合。     

基于透射法的能见度测量装置的误差分析

介绍了透射法测量能见度的基本原理,给出了一种基于透射法的能见度测量装置的设计及其性能指标。详细分析了该装置测量能见度的主要误差来源,包括:数学模型、硬件系统、实验方法和环境等四个方面。总结这些误差来源对测量结果的影响,并对如何减小误差影响提出建议。     

活性炭纤维对低浓度污染物吸附性能的实验研究

为了解活性炭纤维对室内低浓度污染物的吸附性能及其影响因素,以甲醛为模拟污染物,通过改变污染物的初始浓度以及外界参数(温度、相对湿度、表面风速)对活性炭吸附性能进行了试验研究.实验结果显示:温度和气流速度对活性炭纤维的吸附性能有较大的影响,相对来说温度的影响要大一些;而相对湿度对其的影响则不太明显.并运用吸附动力学方程式和吸附平衡方程式对影响因素进行了分析并与试验结果进行了比较,结果表明实验结果与理论分析相吻合.     

以天然水为原料液的正渗透过程中CTA膜表面污染物脱附研究

选择浓缩天然水作为原料液,研究了错流过滤的正渗透膜系统处理水中有机物时,不同实验温度和错流速度下膜通量的变化;通过对被污染的膜进行洗脱,得到洗脱液,并对洗脱液进行了分析,得到污染物在正渗透膜的沉积规律.结果表明,温度对通量和膜污染影响很大,温度越高膜污染越强,膜通量下降越大;错流速度对通量和膜污染也有明显的影响,错流速度越小膜污染越严重,膜通量下降越大.膜上的污染物主要以蛋白质和氨基酸为主,该类物质主要在发射波长320～360 nm、激发波长210～230 nm的荧光区域有响应.污染物的分子量主要分布在630 000和800左右两个区段.正渗透过程中CTA膜对天然有机物中的腐殖质有很强的抗污能力.     

一种能见度测量修正方法及其应用研究

旨在探索能见度测量的一种修正方法,通过能见度测量装置与参考仪器的能见度测量实验,引入多项式拟合进行修正,极大地减小了测量误差.运用经验公式的测量装置,与参考仪器进行比对实验,验证了修正方法及其公式应用于能见度修正的正确性.     

汽车空调对汽车污染物排放及油耗的影响

对试验车辆进行不同环境状态下的NEDC测试,分析汽车空调附加污染物排放和油耗情况,结果表明:开启空调会导致车辆污染物排放及油耗不同程度的增加,在环境温度30℃,光照强度850 W/m~2,空调设置温度为22℃时,油耗增加1.78～3.43 L/100 km,污染物排放量增加0.002～0.138 g/km。环境温度对汽车空调附加油耗的影响最为明显,光照强度次之;环境温度每增加5℃,空调附加油耗升高0.2～0.3 L/100 km;光照强度每增加100 W/m~2,空调附加油耗升高0.07～0.09 L/100 km。     

气溶胶吸湿特性研究现状

综述近30年来国内外对气溶胶吸湿性研究的实验方法和研究结果,并分析影响气溶胶吸湿性的各种内在和外在因素,介绍加湿串联差分迁移分析仪(H-TDMA)在过去的25年研究中被广泛用来进行细粒子在不同相对湿度下的吸湿特性试验。通过试验发现:不同成分气溶胶吸湿生长情况不同;无机水溶性气溶胶一般具有较强的吸湿性,而有机组分对气溶胶吸湿性的影响有较大差异。在大气环境测量中,发现来自生物质燃烧的气溶胶在相对湿度大于80%时出现单峰及双峰,在城市区域观察到多峰现象,这说明由于混合状态不同以及组分不同将导致气溶胶吸湿长大行为的变化。     

Air flow through a non-airconditioned bus with open windows

Open window buses without air-conditioning are a major mode of urban and inter-city transport in most countries. High occupancy combined with hot and humid conditions makes travel in these buses quite uncomfortable. In this study air flow through a bus has been studied that could be the basis for low cost and eco-friendly methods of increasing passenger comfort and possibly reduce drag. The aerodynamics of such a road vehicle has not been studied as previous investigations have been confined to vehicles with closed windows that present a smooth exterior to air flow. Using a 1:25 scaled Perspex model of an urban bus in Delhi, flow visualization was performed in a water channel. The Reynolds numbers were one-tenth of a real bus moving at 10 m/s. Smoke and tuft visualizations were also performed on an urban bus at 40 km/h. Numerical simulations were performed at the actual Reynolds number. Even though there were Reynolds number differences, the broad features were similar. Air enters the bus from the rear windows, moves to the front (relative to the bus) and exits from the front windows. Inside air velocity relative to the bus is about one-tenth of the free-stream velocity. The flow is highly three-dimensional and unsteady.     

Effect of water soluble polymers on the early age shrinkage of cementitious composites by using the ring test method

The effect of water soluble polymers (WSP) on the shrinkage deformation at an early age is reported in this paper. Commercially available hydroxy propyl methyl cellulose (HPMC) with two different molecular weights was employed in the cementitious composites with various mixing ratios. A restrained shrinkage test was conducted with a steel ring in accordance with ASTM C1581-04. In addition to the steel ring's strain, the surface tension, viscosity, internal relative humidity (RH) and crack propagation were also investigated. The polymer-modified cementitious composites were found to be effective in reducing the crack tendency by extending the age at cracking in comparison to the control mixture. The test results also illustrated that the age at cracking significantly correlated with the restrained strain and the stress development, which were influenced by the relative humidity of the cementitious composite. The higher relative humidity that was maintained in the WSP specimen at an early age was due to the modified pore solution's viscosity. Both the viscosity and the surface tension of the pore solution were two major factors that affected the stress rate. A higher internal relative humidity and a lower surface tension contributed to a smaller stress rate. Nevertheless, the computed crack strain of the WSP showed no relationship to the cracking tendency.     

Equilibrium moisture content of earth bricks biocomposites stabilized with cement and gypsum

In recent years, energy efficient and ecologically friendly buildings have been important in the housing and construction sector. One of the major barriers to producing good and useful products is the lack of detailed information about natural materials, in particular their moisture related properties, as these materials are hygroscopic and sensitive to moisture. This research aimed to determine the equilibrium moisture content of earth block materials, as an extremely important characteristic variable for all physical simulations. Earth bricks with different compositions were fabricated from cohesive soil, cement, and gypsum combined with two kinds of natural fibers. Wheat and barley straw were used as reinforcing fibers and materials were treated at various temperatures (10–40 °C) and relative humidity (33–95%). The moisture content was considered in dynamic equilibrium with the environmental conditions and the effects of relative humidity and temperature were investigated. The effect of relative humidity was observed more pronounced than that of temperature. The test results are discussed with reference to the relevance of the earth bricks as an ecologically friendly building material that is directly associated with the moisture related properties of buildings. The results also showed significant improvement in the durability.     

Attitudes towards current and lowered speed limits in Australia

The present study was concerned with gaining a greater understanding of the Australian community's attitudes towards both the current and proposed lower speed limits. An online survey was administered in four states (Victoria, South Australia, Western Australia, and Tasmania), with a total of 4100 respondents recruited. The survey focussed on attitudes towards speed limits for four different road types, and the sample was stratified according to age, gender, and area of residence. It was found that most respondents were able to correctly identify the speed limit for local residential streets and major urban arterials, although their knowledge of rural speed limits was considerably lower. The majority of respondents were in favour of the proposed lower speed limits on 100 km/h two-lane undivided rural roads and on rural gravel roads, but only about one-third supported lower limits in urban areas. A cluster analysis revealed that there were varying characteristics between respondents who were more or less likely to support speed limit reductions, across a number of demographic, socio-economic status, and driving behavior variables. These results provided important guidance regarding groups that could potentially be targeted in speed-related interventions, as well as highlighting the potential for lowering speed limits in Australia, particularly on rural roads.     

Characteristics of aerosol optical properties in pollution and Asian dust episodes over Beijing, China

Aerosol optical properties were continuously measured with the National Institute for Environmental Studies (NIES) compact Raman lidar over Beijing, China, from 15 to 31 December 2007. The results indicated that in a moderate pollution episode, the averaged aerosol extinction below 1 km height was 0.39+/-0.15 km(-1) and the lidar ratio was 60.8+/-13.5 sr; in heavy pollution episode, they were 1.97+/-0.91 km(-1) and 43.7+/-8.3 sr; in an Asian dust episode, they were 0.33+/-0.11 km(-1) and 38.3+/-9.8 sr. The total depolarization ratio was mostly below 10% in the pollution episode, whereas it was larger than 20% in the Asian dust episode. The distinct characteristics of aerosol optical properties in moderate and heavy pollution episodes were attributed to the difference in air mass trajectory and the ambient atmospheric conditions such as relative humidity.     

Preservation of Photographs

Photogrophs ore susceptible to degradation (rom many sources. Attock on the imoge or bose can occur (rom residual processing chemicals. industrial atmospheric pollutants, contaminants (rom storage area construction materials or (rom the materials used (or mounting and containing the pictures. Degradation (rom poor processing can be detected with simple chemical tests. Until more becomes known about the many products normally associated with the preservation o( photographs, one should avoid using in the storage area fresh point, raw woods and volatile substances, and near or on the photographs avoid adhesives, plastics and poor quality papers. Regardless o( the preservation technique used it is help(ul to remember that the storage li(e of photographs can be extended by slowing down chemical activity. This can be achieved by care(ul control a( storage temperature and relative humidity (60 references).     

Experimental evaluation of fog warning system

Highway safety is a major concern to the public and to transportation professionals, so the number of crashes caused by poor visibility due to fog form an alarming statistic. Drivers respond to poor visibility conditions in different ways: some slow down; others do not. Many drivers simply follow the taillights of the vehicle ahead. Accordingly, hazardous conditions are created in which speeds are both too high for the prevailing conditions and highly variable. Findings are presented from a study of traffic crashes due to fog in the southern region of Saudi Arabia. The primary objective was to assess the effectiveness of fog detection and warning system on driver behavior regarding speed and headway. This warning system includes visibility sensors that automatically activate a variable message sign that posts an advisory speed when hazardous conditions due to fog occur. The system was installed on a 2 km section of a two-lane, rural highway. A data set of 36,013 observations from both experimental and control sections at two study sites was collected and analyzed. The data included vehicle speed, volume, and classification; time headway, time of day, and visibility distance. Although the warning system was ineffective in reducing speed variability, mean speed throughout the experimental sections was reduced by about 6.5 kph. This reduction indicates that the warning system appeared to have a positive effect on driver behavior in fog even though the observed mean speeds were still higher than the posted advisory speed. From relationships found in the literature between mean driving speed and number of crashes, a speed reduction of only 5 kph would yield a 15% decrease in the number of crashes.     

An Optimal Method for High-Resolution Population Geo-Spatial Data

Mainland China has a poor distribution of meteorological stations. Existing models’ estimation accuracy for creating high-resolution surfaces of meteorological data is restricted for air temperature, and low for relative humidity and wind speed (few studies reported). This study compared the typical generalized additive model (GAM) and autoencoder-based residual neural network (hereafter, residual network for short) in terms of predicting three meteorological parameters, namely air temperature, relative humidity, and wind speed, using data from 824 monitoring stations across China’s mainland in 2015. The performance of the two models was assessed using a 10-fold cross-validation procedure. The air temperature models employ basic variables such as latitude, longitude, elevation, and the day of the year. The relative humidity models employ air temperature and ozone concentration as covariates, while the wind speed models use wind speed coarse-resolution reanalysis data as covariates, in addition to the fundamental variables. Spatial coordinates represent spatial variation, while the time index of the day captures time variation in our spatiotemporal models. In comparison to GAM, the residual network considerably improved prediction accuracy: on average, the coefficient of variation (CV) R² of the three meteorological parameters rose by 0.21, CV root-mean square (RMSE) fell by 37%, and the relative humidity model improved the most. The accuracy of relative humidity models was considerably improved once the monthly index was included, demonstrating that varied amounts of temporal variables are crucial for relative humidity models. We also spoke about the benefits and drawbacks of using coarse resolution reanalysis data and closest neighbor values as variables. In comparison to classic GAMs, this study indicates that the residual network model may considerably increase the accuracy of national high spatial (1 km) and temporal (daily) resolution meteorological data. Our findings have implications for high-resolution and high-accuracy meteorological parameter mapping in China.