被引排行
Emergency shelter amount confirm and location optimized
ZHOU Xiao-meng,LIU Mao,WANG Yang(The Research Center of Urban Public Safety,Nankai University,Tianjin 300071,China)It is an important measure for the international society establishing the emergency shelter to deal with the emergent events and victims.And also,the emergency shelter is the temporary living place for people in modern big cities to avoid the danger of natural disasters,such as the earthquake,fire,explosion,flood,and so on.In this paper,based on the layout rule of the emergency shelter and the emergency location,the ascertain method of the amount and the volume emergency shelter is developed.Beside that,the optimize network model is also studied to solve emergency shelter location problems.
Experimental research on mechanical properties of different type of concrete after high temperature
YU Zhi-wu,DING Fa-xing,LUO Jian-ping(College of Civil Architectural Engineering,Central South University,Changsha 410075,China)The present paper aims to introduce the authors' experimental research on the mechanical properties of C40,C50 ordinary concrete and C80 high-performance concrete(HPC) when high temperature is applied to it.For this purpose,the authors have given a detailed review of experimental phenomena and the influences of the significant parameters,such as peak temperature,exposure time,different size of specimens,cooling regimes and different types of concrete on the mechanical properties of concrete after high temperature were provided.And then,the paper has given a formula for stress-strain relationship of normal and high-performance concrete when high temperature is applied to it.Next,some empirical calculation formulas for axial compressive strength,elastic modulus and peak strain were proposed.The results of the authors' research indicate that: with the exposure of temperature with the exposure time increases,cube compressive strength,axial compressive strength and the elastic modulus of concrete tend to decrease as a whole while peak strain for concrete tends to increase.On the condition that the peak temperature and temperature exposure time are the same,the loss of compressive strength proves greater for big specimen size than for small ones,greater for water cooling than for furnace cooling and greater for high-performance concrete than for ordinary concrete.
DISPOSAL AND TREATMENT OF MUNICIPAL SOLID WASTE:STATE-OF-THE-ART
ZHANG Xian-sheng 1, SHEN Ji-min 1, LI Wei 1, XIE Qiang 1,2 (1 School of Chemical and Engineering Technology, China University of Mining and Technology, Xuzhou 221008, Jiangsu, China; 2 School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, China)A literature survey on quantity and characteristics of municipal solid waste (MSW) in typical cities all over the world, the methods and technologies available for disposal and treatment of MSW, and the progress in research and development of these technologies as well, was given in this paper. Further more, both issues and the causes resulted in these issues in management of MSW in China were discussed. It is concluded that in a rather long time in future landfill will be the dominant way in the treatment of MSW in China, meanwhile proportion of MSW disposal by means of sanitary landfill will increase gradually. Although compost of MSW will also play an important role, its application is dependent on its products' distribution. As incineration can reduce MSW volume by up to 90% and decrease MSW weight by 75%, when the following factors, such as stable increase of heating value of MSW in china, rapid decrease of land suitable for landfilling, are taken into account, it is self evident that incineration will be a promising technology for the treatment of MSW in China.
Testing and determination of the olfactory thresholds of the 40 kinds of typical malodorous substances
WANG Gen;ZHAI Zeng-xiu;GENG Jing;HAN Meng;LU Fu-lei;The given article is inclined to introduce the results of its testing and determination of the olfactory thresholds of 40 kinds of typical malodorous substances.For the said purpose,we have first of all selected 40 kinds of typical malodorous substances while searching through the domestic and foreign literature with the analysis results of the odor samples commonly used in all the industrial branches.The said substances belong to 5 kinds of typical malodorous substances,such as the sulfur compounds,nitrogen compounds,benzene series,olefins and oxygenated organic compounds.According to the air quality-testing and determination of the odor-triangle odor bag method(GB/T 14675—93),we have worked out the olfactory thresholds of the aforementioned substances with a certain concentration gradient of the standard gas.As a result of our testing and determination,we have established a database of the typical malodorous substances with the said method.In addition,we have also managed to classify the olfactory threshold range of the said 40 substances into three ranks:higher thresholds(10-1×10-6-10×10-6),middle thresholds(10-3×10-6-10-2×10-6),the lower thresholds(10-5×10-6-10-4×10-6).In so doing,we have made a careful depiction of the odor quality of the substrates respectively and a preliminary analysis of the relationship between the molecular structure and the threshold data.As a result,we have found that there exists great difference in the odor characteristics for the different substances.For example,benzene serial compounds tend to produce a smell of aroma;the sulfur compounds enjoy the priority to give off a rotten egg smell;the same is true to the hydrogen sulfide.On the other hand,nitrogen compounds tend to produce a stimulating odor as ammonia.As to the aldehydes and esters,they prefer mainly to deliver flower or fruit fragrance,while acids are endowed primarily with a smell of sweat.Thus,the analysis and the application of olfactory thresholds in the stench pollution control,helps us to know that it is of great significance and interest to choose and remove the malodor substance effectively as well as to remove,prevent and control the stench pollution in hoping to improve the ecological environment.
Water environmental health risk assessment of Xiangjiang River
SUN Shu-qing, HU Guo-hua, WANG Yong-ze, LI Cheng(School of River & Ocean Engineering, Changsha University of Science & Technology, Changsha 410076, China)The present paper introduces the author's research of the water environmental health risk assessment for the main reaches of Xiangjiang River, the most important river areas in Hunan province, based on the model for water environmental health risk analysis recommended by USEPA and the monitoring data in the year 2000. The result of the research shows that the greatest health risk to the individual person per year in terms of non-carcinogens through drinking is Pb, followed by Hg. And the greatest health risk for individual person per year in terms of carcinogens are As and Cd which are higher than the standard 5.0×10 -5 a -1 recommended by ICRP. Thus it can be seen that the health risk for the individual person caused by chemical carcinogens is far greater than non-carcinogens, to which must be paid much greater attention. Another fact found from the experiment is that the water quality of Xiangjiang River above Fengxi in Zhuzhou proves better, but that of Xiangjiang River lower than Zhouzhu proves worse. The most heavily polluted section is Songbai section in Hengyang. Its greatest health risk to individual person per year can be ten times as high as the standard value recommended by ICRP, which are in the sections at Xiawan in Zhuzhou, Wuxing section in Xiangtan and Sanchaji section in Changsha, twice higher than the value recommended by ICRP. Thus, it can be seen that the reach of River Xiangjiang from Hengyang to Changsha are the key to the water pollution control and treatment of the whole River. The application experiment results show that the assessment models can both describe quantitatively and qualitatively the seriousness of the pollution on the public health and the risk of the entire social environment. Though the Environmental Health Risk Assessment (EHRA) is not required in the environmental assessment for the time being in China, it should be included in the environmental assessment. Therefore, the EHRA is a new assessment method.
Study on adsorption of heavy metal ions onto insolublized humic acid
MA Ming-guang, ZHOU Min, JIANG Yu-feng, WU Ying-qin, ZHANG Yuan, CHEN Hui (Chemistry & Chemical Engineering College, Northwest Normal University, Lanzhou 730070, China)The present paper has investigated the removal of heavy metals Pb 2+, Cd 2+ and Cu 2+ from the aqueous solutions by adsorption onto insoluble humic acid (IHA) at different pH and temperatures. As is known, insoluble humic acid (IHA) has an excellent adsorptive ability, which can be prepared by heating the highly soluble HA at 330 ℃ and the treated with 2 mol/L CaCl2 solution. The insoluble humic acid are characterized by such means as thermo-gravimetry and differential thermal analysis (TG-DTA) as well as scanning electron micrograph (SEM). While investigating the effect of temperature, pH and time on the adsorption behaviors of heavy metals, it has found that the adsorption capacity increases with the increase of the temperature and pH. At the same time, the paper has also analyzed the adsorption experimental data by using three different isotherm models: Langmuir, Frendlich and Linear isotherm. As the result, it has obtained the optimal correlation for Frendlich isotherm equations. In addition, the paper has calculated the thermodynamic quantities ΔH in accordance with the Clausius-Claperyon,s theory. The ΔH values for Pb 2+,Cd 2+ and Cu 2+ prove to be -75.37 J/mol, -117.92 J/mol and -110.76 J/mol, respectively, which are smaller than the lower limit of the chenmisorption (42.0 kJ/mol ). It means that the type of adsorption of Pb 2+,Cd 2+ and Cu 2+ onto IHA is physisorption, rather than by chemical bonding. And finally, the adsorption equilibrium gained within 12 hours, and a high and stable removal of heavy metals on insoluble humic acid has been obtained almost under the neutral conditions. The above results suggests that IHA is a potentially efficient absorbent to purify water from the heavy metal contaminants.
Characteristics and mechanism of road traffic accidents
GAO Yinan;GONG Jianqiang;To study the characteristics and mechanism of road traffic accidents, the cause, form, time, perpetrator, motor vehicle, casualties, and other characteristics were analyzed based on the data of 1.09 million road traffic accidents in 2015-2019, and then causative factors of road traffic accidents were abstracted. The Decision Making Trial and Evaluation Laboratory(DEMATEL) method was used to calculate the correlation of complex system, and the influence degree, affected degree, cause degree, and center degree of causative factors were calculated to determine the impact of each causative factor on the formation of road traffic accidents. A hierarchical structure diagram of causing factors of road traffic accidents was established. The mechanism and essential causative factors of road traffic accidents were obtained theoretically. Based on the analysis of the characteristics and causes of road traffic accidents, suggestions on road traffic safety management in line with national conditions were proposed. 86.29% of the accidents were caused by motor vehicle violations. Among them, failure to give way according to regulations was the main reason, illegal loading was a high-risk factor, and speeding accidents were frequent and harmful. 70.21% of the accidents were multi-vehicle accidents. Side impact was a high-frequency accident form, and falling and rolling were high-risk accident forms. 17:00-19:59 was the accident-prone period. 3:00-5:59 was the period of high injury accidents. Accidents caused by production and operation vehicles were accompanied by high hazards, among which tourism passenger transport, transport of dangerous chemicals, and general freight transport caused the highest degree of damage. Pedestrians were more vulnerable to fatal injuries and men were more likely to be injured than women in accidents. 77.38% of the fatal causes of accidents were brain injuries. 3.63% of the motor vehicles involved in accidents had mechanical failures, the probability of poor braking was the highest, and the danger of excessive tire wear was the greatest. The analysis results of the mechanism show that speeding, overloaded transportation, insufficient technology or lagging standards and regulations are the essential factors. These factors can be used as key points to reduce accident risk.
Experimental study of wetting chemical dust-depressor
JIN Long-zhe YANG Ji-xing OU Sheng-nan (School of Civil and Environment Engineering,University of Science and Technology Beijing,Beijing 100083,China)This article is concerned with the author's systematic study of the wetting chemical dust-depressor.Based on the study of many moisture-absorption materials and their moisture absorption and retention,and wetting capability of some surface active agents by comparison,this article has chosen calcium chloride and magnesium chloride as its basic dust-depressor and accessories.As one of the basic dust control measures,wetting chemical dust-depressor has been more and more widely used and received growing recognition. Based on the analysis of dust-depressing mechanism,we have deter- mined the moisture content of the dust in relation with the dosage of the moisture-absorbing materials.As a result,we have found that it is better to adopt calcium chloride and magnesium chloride for the given purpose,for they enjoy stronger moisture absorbing and retain- ing capabilities than other corresponding materials.Moreover,we have also fuand that the sedimentation rate of coal dust can be raised by increasing the dosage of such agents.For example,in the solution of Triton X-100,the sedimentation rate can be made to reach its opti- mal value in some proper manner.In addition,we have confected some dust-depressing furmulae from calcium chloride,magnesium chloride and Triton X-100 in different proportions,and applied them to our laboratory experiments.And in our laboratory experiments,we have discovered that the moisture content of dust for dust-depressor can be made much higher than water,and the result can be height- ened with the increase of dust-depressor dosage.Furthermore,it can be concluded that Formula 7 would be the best one in comparison with other formulae.Thus,the results of our experiments would con- tribute greatly to the optimization of the dust-depressor formulation, which can be applied to the field experiments,where the moisture con- tent of dust is sprayed as depressing solution with much higher effects than just spraying water.Besides,the dust-depressing effect can last much longer on the roads than spraying other sulutions.In case of ac- tual use on the surface of the road,the dust concentration can be made to keep lower than 10 mg/m3 at least 4 days,which would naturally prove the actual value of the dust-depressor we have suggested here.
Effects of water control on rice growth and its intake of cadmium on Cd contaminated soil
ZHANG Li-na1,ZONG Liang-gang1,FU Shi-jing1, SHEN Zhen-guo2(1 College of Resources and Environmental Science,Nanjing Agricultural University,Nanjing 210095,China;2 College of Life Science,Nanjing Agricultural University,Nanjing 210095,China)The present article is aimed at reporting the authors' pot rice-growing experiments in hoping to investigate the effects of different ways of water control on rice yields and its intake of Cd,that is,continuous flooding,dry cultivation and mid-way drainage in different growing stages.The results of our experiments indicate that dry cultivation brings about remarkable effects on the rice growth and brings about the lowest yields.Compared with the continuous flooding,dry cultivation tends to decrease the rice yields by 28.74%.On the other hand,continuous flooding tends to bring about relatively higher yields,but not the highest.Drainage at tillering and filling periods could increase the rice yields more remarkably than continuous flooding,that is,by 14.58% vs.10.27%.The content of Cd in brown rice proves the least with the continuous flooding,while the dry cultivation and midseason drainage in different growing stages tend to increase its content in brown rice,which appears most obviously with dry cultivation.In our experiments,dry cultivation has brought about an increase of Cd content as high as by 166.31%.On the other hand,the influence on Cd content in brown rice with the mid-way drainage proves weakest.Thus,it can be concluded that continuous flooding is the most favorable to be chosen as a cultivation method on Cd contaminated soil,with the drainage cultivation following.In addition,dry cultivation is also likely to affect rice growth with an obvious increase of the Cd content,for which it is unfavorable to be chosen on Cd contaminated soil.
EXPERIMENT WITH EFFECT OF CADMIUM ON ACTIVITY OF SUPEROXIDE DISMUTASE IN GILL AND LIVER TISSUE OF CRUCIAN
YANG Li hua, FANG Zhan qiang, ZHENG Wen biao, WU Yu yuan, MA Guang zhi (College of Life Science, South China Normal University, Guangzhou 510631, China)This paper presents an experiment the author has done with the crucian when it was exposed to cadmium to test the influence of the cadmium polluted sludge on the fish activities. With crucian exposed to cadmium (CdCl 2·2.5H 2O) with 0 mg/L, 0.73 mg/L, 1.46 mg/L, 2.95 mg/L for 6 days, the authors intend to determine the activities of superoxide dismutase (SOD) of gill and liver tissues in 144 h by means of improved pyrogallol autoxidation. The results of the experiment indicate that the activities of SOD in gill and liver haven't made any obvious change at low Cd concentrations in a short time. The activities of SOD, however, would increase with the exposure time going on, which may probably come about as a result of the "Toxic excitement effect". With the high concentration Cd inhibiting the activities of SOD in gill and liver, the inhibiting strength will increase with the prolonging of the exposure time and the concentration enhancing. Thus, it suggests that the harm caused by active oxygen due to the decrease of the activities of SOD is an important reason that leads to the mass death of crucian exposed to Cd. The experiment also indicates that the activities and sensitivities to Cd of SOD in liver are higher than those in gill, which may be associated with their physiological functions.