被引排行
Study on evaluation models of severity degree of dam failure impact
LI Lei, WANG Ren-zhong, SHENG Jin-bao(Dam safety and management department of Nanjing Hydraulic Research Institute, Dam Safety Management Center of the Ministry of Water Resources, Nanjing 210029, China)Dam risk assessment technique has already been used in the field of dam safety management abroad especially in Canada, Australia and USA in recent twenty years. There are more than 85 000 dams in China and about one-third of them are with severe deficiency and in high risks. Therefore it is real necessary to use this kind of technique to assist prioritizing dam maintenance or rehabilitation, reducing risks caused by dam failure. The technique consists of two important research objectives, dam-break probability analysis and dam failure impact evaluation. Dam failure impact includes three main factors: loss of life, financial loss, society and environment. How to evaluate the severity degree by means of these three factors comprehensively is a challenge of dam rehabilitation decision-making. The paper is to present a comprehensive evaluation coefficient for dam-break severity degree. The study introduces integrative assessment function L which considered weights Si respectively of life loss, financial loss, society and environment, and their severity coefficients Fi, formed as linear weighted sum method. In order to integrate loss of life, financial loss, society and environment in accordance with existing laws and regulations in China, logarithm non-linear or linear models of data normalization are established to deal with their different units. A series of quantitative values of L which divide disaster event into deferent degree are suggested according to Chinese situation. The method and evaluation model is practically applied at 5 reservoir dams to appraise their severity degree of failure impact respectively and the comparison of these results are made to decide which one is more severe. The analyzed result shows that hazard of all these 5 dams would be extreme severe and should report to State Council as soon as the event of dam break occur.
Research progress of heterotrophic nitrification-aerobic denitrification in biological denitrification
QIAO Sen;LIU Xue-jie;ZHOU Ji-ti;Key Laboratory of Industrial Ecology and Environmental Engineering of the Ministry of Education,School of Environmental Science & Technology,Dalian University of Technology;The paper is dedicated to making a research progress re view on the heterotrophic nitrification-aerobic denitrification in bio logical denitrification. It is for this purpose that we have made an in vestigation of the bacteria capable of combined heterotrophic nitrifi cation and aerobic denitrification as potential microorganisms in the biological nitrogen removal system. As is known,biological denitrifi cation is the main process in removing ammonia-N compounds from the sewage. Actually,the discovery of heterotrophic nitrification-aer obic denitrification( HN-AD) is a process of the enrichment and breakthrough of the conventional nitrification-denitrification process,which tends to isolate certain bacteria from the soils,pools and sew age treatment systems. As compared with the conventional denitrifi cation,HN-AD has the following advantages:( 1) Simultaneous re moval of COD and nitrogen is carried out by utilizing the organic substrates and tolerance to oxygen to achieve nitrification and deni trification in a single-stage reactor,which can help to reduce the space and construction cost;( 2) ammonia nitrogen can mainly be converted into gaseous products with no accumulation of NO-2-N NO-3-N;( 3) the high growth rate of heterotrophs can be made easily retained in the treatment system;( 4) the diversity of possible sub strates and products of heterotrophic nitrification-aerobic denitrifier helps to facilitate the mixed culture with a variety of bacterial strain and expand the scope of the possible applications. Therefore,close attention should be paid to HN-AD bacteria for the sewage treat ment. Thus,from what we have said above,the purpose of this pa per is just to provide a critical review on the HN-AD and delineate its basic definition and mechanism of the typical HN-AD bacteria,with the focus aiming to review the denitrification characteristic fea tures of some isolated typical HN-AD bacteria in recent years and analyze the optimum parameters of the denitrification. And,finally,we would like to make an introduction to the present situation and potential applications of sewage treatment by HN-AD bacteria,and also outlined the challenges and future research tendency will be pu on the HN-AD.
On assessment method to emergency shelter adaptation by using the statistic theory for fuzzy centralization
WU Zong-zhi~1,HUANG Dian-jian~2,CAI Si-jing~2,JIANG Zhong-an~2 (1 China Academy of Safety Science & Technology,Beijing 100029,China;2 Civil and Environment School,Beijing University of Science & Technology,Beijing 100083,China)The paper aims to present the authors' research on an Assessment Approach to emergency shelter adaptation by using the statistic theory for fuzzy centralization based on the analytic hierarchy processing(AHP).In our research we have selected 18 assessment indexes.The whole research has been done around the planning,internal hardware and external software environment,according to the inherent characteristics of the urban emergency shelter,then followed by an analysis of the hierarchical comprehensive assessment model of factors,which may affect the emergency shelter adaptation.Based on the theory of fuzzy centralization statistics,the total weights of all the indexes are brought about for the reliability analysis.The assessment conclusion can be drawn through the linear adding weight model.The results of analysis indicate that the value of emergency adaptation is good via one example in Beijing.The conclusion also indicates that the assessment method is more objective than other methods and it can be applied to many assessment fields,such as management,resource planning and sustainable development,though the assessment index system is not yet perfect,which leaves much to do in the future.With the ever-speeding-up pace of urbanization and the sprawling of our urban areas,all kinds of haphazard keep happening to our cities from time to time incessantly.Therefore,it is absolutely necessary to improve the assessment for emergency management capacity in hope to reduce the losses and provide quantitative basis for governmental decisions.
A REVIEW OF TOWER CRANE SAFETY
HUANG Hong zhong (School of Mechanical Engineering, Dalian University of Technology, Dalian 116023, Liaoning, China) and YAO Xin sheng (School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China)In the present paper, the development of the tower crane home and abroad is briefly reviewed and the state of the art of the safety of tower crane is analyzed. Tower crane accidents are classified according to the structures of tower crane and the causes of accidents, based on the three year statistics of accidents in eight cities in China.The classified results show that the percentage of toppling accident is the highest,which is 52% (Table 1).Accidents caused by the faults of design,manufacture and operation of tower crane account for 10%,20% and 70% respectively (Table 2).There are eight causes in the category of the accidents during operation of tower crane,i.e,no safety protection device or ineffective device,operation contrary to its instructions or by mistake,disassembling and assembling accident,malmanagement,environmental influences,bad maintenance and electric accident.Some standards and regulations in China are introduced briefly.In the end,the solutions and countermeasures to the safety problems of tower crane are proposed.These include improving the intrinsic safety of tower crane,strengthening the conventional safety management,enhancing the safety education and technical training,analyzing typical accidents and applying advanced techniques and methods. The prospect of the development of the tower crane safety technology is also discussed.
Coupling safety risk assessment of super high-rise building construction based on complex network
YAO Hao;CHEN Chao-yi;SONG Dan-ni;Although construction technology and equipment are constantly updated and improved,construction accidents still often occur. The reason is that the construction process is a complex system behavior involving the interaction of a large number of personnel,machinery,and environmental factors,and risks may be incubated and transmitted at multiple nodes in the system at the same time,and evolve unpredictable results. To strengthen the systematic consideration of safety risks in project management,this paper proposes a coupling assessment method of major safety risks in super high-rise building construction based on a complex network. First of all,based on the case database data,this study focuses on the major safety risks with high frequency and high loss in super high-rise building projects,including tower crane collapse,construction lift ladder cages fall,attached lift scaffold collapse,people falling from high places,people being hit by objects,etc.,and identifies risk factors for a large number of accident cases. Secondly,according to identified risk factors list based on fault tree (FTA) and accident chain (AC)analysis method,this method builds the model of a complex network of coupled risk factors,weighted by using the risk entropy (RE) analysis method. Then this study carries on the analysis of characteristics of the complex network. The results show: (1)most of the network nodes are discrete; (2) risk transfer fast and in wide scope; (3) key nodes exist in the risk system and controlling the spread of these key points can effectively block the risk in the system. Thirdly,based on the established model,the occurrence coupling of risk events was evaluated through the multi-path evolution analysis based on the Depth-First Search (DFS) algorithm. Then,based on the accident chain transfer analysis,the heavy-duty coupling assessment of risk events is carried out. Finally,the risk coupling comprehensive assessment results are formed. In this paper,the evaluation method is applied in a case study. The results are compared with the traditional risk level evaluation,which shows that the evaluation for each risk event is improved to varying degrees,which is more in line with the perception of risks in the construction of super highrise buildings and is conducive to the targeted strengthening of control efforts,reasonable allocation of safety management resources as well as prevention of accidents.
Risk assessment on the tunnel collapse probability by the theory of extenics in combination with the entropy weight and matter-element model
YANG Zhuo;RONG Xiao-li;LU Hao;DONG Xin;In this paper,we would like to introduce a new evaluation model for the tunnel collapse we have developed based on the entropy-weight and matter element extension theory. Seeing the serious current situation with the underground engineering safety,we have worked out a new model for the collapse evaluation to be trial-employed in one tunnel,by taking into careful account all the indexes of the tunnel collapse probability. Furthermore,we have chosen seven main factors through comprehensive and statistical analysis and investigated the tunnel collapse influential factors. The aforementioned factors of the said model include the surrounding rock grade,the excavation progress,the angle of the unsymmetrical pressure,the tunnel depth,the impact of the groundwater situation on the engi-neering progress,the shattered fault zone,the construction management as well as the technical levels. To improve and heighten the applicability of the model,we have combined the entropy weight with the extension theory for evaluating such collapse risks. To achieve more realistic results,we have quantified all the indicators in hoping to avoid any obscure and indefinite description,trying to carry out the dimensionless method in analyzing the related indicators. And,then,we have established the classic domains,the joint domains and the matter elements to review the tunnel collapse grade assessment results with the element analysis extension theory and determine further the weights of the indicators properly with the use of the said entropy weights. At the same time,we have also analyzed the correlation degree,the tunnel collapse risk level and the variable characteristic values. And,finally,we have made an attempt to adopt our model to the engineering practice to deal with the problems of one tunnel,and in turn we have found the surrounding rock of the excavation face unstable,resulting in the rock falling. Proven that the evaluation result of the new model is consistent with the actual phenomenon,it can be expected to be suitable for the tunnel collapse evaluation need. What is more,it can also be used to evaluate other similar projects of underground engineering to provide effective ways for assessing such tunnel collapse cases.
Research on preparation of activated carbon adsorbent from sewage sludge and its application
YU Lan-lan, ZHONG Qin,FENG Lan-lan(School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China)The paper aims at introducing the authors' study on the different influential factors on the adsorbent capability of the activated products by taking the surplus sludge as raw material. It has also introduced different activating ways to prepare the activated carbon adsorbent and contrasting the effects of different activators. The results of our study reveal that the activated carbon adsorbent made by way of chemical activation proves better with the optimum activator being complex of ZnCl2 and H_2SO4. Moreover, the optimum preparation conditions are concentration of two activators 5 mol·L -1(the ratio of ZnCl2 and H_2SO4 is 2:1), at the activating temperature of 550 ℃, in the proportion of solid to liquid 1∶2.5, in a period of 2 h. The capacity of iodine adsorption was 488.02 mg·g -1, at the rate of 86.6%. The stage of weight loss of dry sludge occurred at 244.62 ℃(approximately 34.19%). The adsorbent gained can be used to treatment wastewater to effectively remove organic substances. It can also be found that the adsorbent amount may have strong effect on the adsorption of the organic substances in wastewater treatment. On the condition that the activated carbon adsorbent concentration is 0.5%, the removing rate of COD will be 68.18% with the equilibrium adsorption time being about 60 min, and the equilibrium adsorption capacity41.24 mg·g -1. If the chromaticity color of wastewater is improved, the treatment effect turns better than the commodity of pellet carbon, the removing rate of COD of commodity of pellet carbon is 48.72%, and the equilibrium adsorption time is approximately 90 min, the equilibrium adsorption capacity is 30.78 mg·g -1. Therefore,the performance of the adsorption of activated carbon adsorbent made from sewage sludge proves positive.
An innovated quantitative model of the optimal resource allocation in case of emergency
ZHOU Xiao-meng JIANG Li-zhen ZHANG Yun-long (Urban Public Safety Research Centre,Nankai University,Tianjin 300071,China)Aiming at solving the resource allocation problems in case of emergency events,the paper presents an optimum mathematical simulation model based on the dynamic programming.In accordance with the number of emergency spots,the given model tries to divide the resource allocation procedure into the some stages.The stated variable stands for the amount of the emergency resource available for allocation can be used at the beginning of each stage.As is depicted in the dynamic programming theory,the remaining resource of the previous stage may have a strong influence on the succeeding stage. During each stage,three factors may restrict the object function,that is,the remaining resource,the decision,and the demand.The total function is the sum of the object function of each stage.In addition, the concrete case can be used to confirm the model's validity and practicability.The results of our repetitive experimental application of the model show that it works perfectly for its duty in improving the ef- ficiency of emergency management and overcoming the problem of wasting emergency resource as well as low efficiency in emergency rescue.
Research on safety risk assessment of prefabricated buildings based on game theory-regret theory
FAN Cheng-wei;MING Xing-fen;FU Xiao-hong;HU Qi-zhi;This study aims at establishing a new comprehensive evaluation model for the construction safety of the prefabricated buildings based on the game theory and the regret theory in terms of the fuzziness and randomness of the construction safety of prefabricated buildings. For this purpose, we first made a thorough analysis of the chief factors affecting the construction safety of prefabricated buildings, mainly including the following 14 factors: technology level and safety awareness of operators, safety management ability of manager, compliance with safety system, repair and maintenance of construction equipment, early warning and emergency treatment of safety accident, safety education and training on the spot, natural environment, and workplace environment, etc. Besides, a comprehensive evaluation index system was constructed based on four factors: human, material, management, and environment. All of the factors mentioned above should be categorized into 5 levels. Secondly, what is also worth mentioning is that, in the given paper, we managed to improve the analytic hierarchy process and the improved critical method for determining the subjective and objective weights for each index, and introduced the game theory to find the comprehensive weights of each index. The regret theory was applied to determine the regret utility. Therefore, we can obtain the comprehensive risk assessment value based on the weights and the regret utility, as well as the construction safety of prefabricated buildings degree on the degree principle. Finally, the comprehensive evaluation model based on game theory and regret theory was applied to evaluate the construction safety of prefabricated buildings. The evaluation results of the model were compared with other models, which are fully consistent with the results of TOPSIS and cloud model in line with the actual investigation on the spot. This study can provide a new idea for the construction safety evaluation of prefabricated buildings.
Desorption enhancement of diesel by humic sodium and surfactants in loess soil
WANG Hai-tao,ZHU Kun,WEI Xiang,LIANG Ying,LU Xiao-yan (Institute of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China)The present paper aims to introduce the authors' experiment on how to remove the diesel contaminant from the loess soil by using the surfactant solutions and humic sodium. In our experiment, we have adopted three anionic surfactants (LAS, SDS and SAS) to analyze their removing power of diesel from the contaminated loess soil. The experiments have shown that diesel contaminants can be synergistically dissolved and absorbed by the three anionic surfactants. The removing power can be as high as up to 63% at a range of anionic surfactant solution from 0.1% to 1.0%. With the increase of humic sodium concentration, the removing efficiency can be well linearly increased by using SDS. However, SAS and LAS had a point of reflection on the adsorption curve when the concentration of humic sodium rise. Therefore, there may exist some inhibiting effect of SAS and LAS on the removing rate of diesel contaminant if the surfactant concentration is over the point.