A nonmetal transportation port with soft soil foundation of Tianjin New Harbor failed during construction in 1997. The soil properties and geological changes before and after landslide were in- vestigated by in situ t...A nonmetal transportation port with soft soil foundation of Tianjin New Harbor failed during construction in 1997. The soil properties and geological changes before and after landslide were in- vestigated by in situ test means. The stability of the slope was estimated with several calculation methods, such as the simplified Bishop method and the non-circle analysis method. According to the investigation and analysis results, the factors that may cause the slope failure can be deter- mined as follows: excessive excavating, violating the normal construction procedure, excessive pore water pressure during earlier piling and sudden water-level fluctuation in front of the slope. Measures to improve the soil foundation for reconstructing the port include strengthening the failed slope with vibro sand piles, filling up the crushed stone layer, dividing the excavation into four steps and driving piles by larger intervals. The port now has been successfully reconstructed and begun operation.展开更多
Goafs are threats to safe mining.Their imaging effects or those of other complex geological bodies are often poor in conventional reflected wave images.Hence,accurate detection of goafs has become an important problem...Goafs are threats to safe mining.Their imaging effects or those of other complex geological bodies are often poor in conventional reflected wave images.Hence,accurate detection of goafs has become an important problem,to be solved with a sense of urgency.Based on scattering theory,we used an equivalent offset method to extract Common Scattering Point gathers,in order to analyze different scattering wave characteristics between Common Scattering Point and Common Mid Point gathers and to compare stack and migration imaging effects.Our research results show that the scattering wave imaging method is more efficient than the conventional imaging method and is therefore a more effective imaging method for detecting goafs and other complex geological bodies.It has important implications for safe mining procedures and infrastructures.展开更多
This paper summarizes the approach, findings and evaluation methodology for a study that investigated the feasibility and potential impacts of street conversion options on traffic operations in downtown Birmingham, A...This paper summarizes the approach, findings and evaluation methodology for a study that investigated the feasibility and potential impacts of street conversion options on traffic operations in downtown Birmingham, Alabama. Of particular interest were issues related to conversion of grid systems from one-way to two-way operations. Recommendations on the most promising design and control configurations for implementation are also provided. A literature review was performed that threw light on the issues and challenges associated with implementation of street conversions, and the available best practices. A comprehensive traffic impact analysis that ensued employed the SYNCHRO computer simulation model to represent current and future operations so as to assess the implications of two-way conversions at and around the test sites. Detailed realistic two-way operations scenarios were developed that considered geometric and right-of-way restrictions, the location of land uses that generate and/or attract vehicular and pedestrian traffic, connectivity with the street grid, and accessibility to nearby freeway facilities, as well as practical concerns.展开更多
There are numerous information technology solutions including hardware and software. A company that provides the solution should have knowledge of the customer needs in the purpose of sailing strategy or upgrade polic...There are numerous information technology solutions including hardware and software. A company that provides the solution should have knowledge of the customer needs in the purpose of sailing strategy or upgrade policy. The needs are also directly connected to the user satisfaction. However, the users have respective points of view in the needs as well as they may not identify the requirements to improve the solution. SERVQUAL can be an appropriate method to define and measure the customer satisfaction for the information technology solutions. As a case study of the customer satisfaction, the modified SERVQUAL items and scoring method are applied to a cyber-infrastructure system named CyberL ab in Korea. The measurement results of user satisfaction for CyberL ab are provided to confirm that our proposed method performs as we intended. From the results, we can score the satisfaction level of users and identify their needs in the various aspects. The total user satisfaction level for CyberL ab is scored by 88.3.展开更多
Network intrusion forensics is an important extension to present security infrastructure,and is becoming the focus of forensics research field.However,comparison with sophisticated multi-stage attacks and volume of se...Network intrusion forensics is an important extension to present security infrastructure,and is becoming the focus of forensics research field.However,comparison with sophisticated multi-stage attacks and volume of sensor data,current practices in network forensic analysis are to manually examine,an error prone,labor-intensive and time consuming process.To solve these problems,in this paper we propose a digital evidence fusion method for network forensics with Dempster-Shafer theory that can detect efficiently computer crime in networked environments,and fuse digital evidence from different sources such as hosts and sub-networks automatically.In the end,we evaluate the method on well-known KDD Cup1999 dataset.The results prove our method is very effective for real-time network forensics,and can provide comprehensible messages for a forensic investigators.展开更多
This article introduces three outstanding innovations, i.e. utilization of the steel casing for the piles to establish a construction platform for Sutong Bridge's large and deep-pile groups; 5000 ton steel cofferd...This article introduces three outstanding innovations, i.e. utilization of the steel casing for the piles to establish a construction platform for Sutong Bridge's large and deep-pile groups; 5000 ton steel cofferdam lowered as a whole and used as a protective structure against impact from ship collision; Permanent scour protection. This article also presents economical and reasonable design method for large bridge foundation and explains the significance of innovation and technical integration to large and complicated project construction based on the above theory.展开更多
Regional development is a course of accumulation based on many factors, which is directly related to resources utilization and conversion. And material wealth production and accumulation embody the outcome of regional...Regional development is a course of accumulation based on many factors, which is directly related to resources utilization and conversion. And material wealth production and accumulation embody the outcome of regional development. Thus, focusing on material wealth, regional development can be evaluated from resources and perspective of resources conversion. Taking the infrastructural level, transportation accessibility and economic development level into full account, the concept of "material-based development" was presented and the material-based development index (MDI) model was established. By using the MDI model, geographic information system technology and mathematic methods, this article then calculated MDI of each county and province of China in 2005 and systematically evaluated the material-based development of China at county and provincial scales, so as to bring some scientific references and policy-making supports to the population development function oriented zoning and population spatial distribution planning of China. The result showed that: (1) At county scale, the material-based development of counties within China in 2005 was significantly different, in which there were 1876 counties belonging to the mid-level material-based development and accounted for 78.10% of the total. The numbers of high-level and low-level counties were 144 and 382 and accounted for 6.00% and 15.90% respectively, demonstrating a spindle shape in general. The spatial distribution of material-based development was unbalanced, and it was much better in southeastern part of the line of "Daxinganling–Yinshan-Liupanshan–southeast edge of Qinghai–Tibet Plateau" than that of northwestern. Furthermore, there were also differences of the sub-index between different material-based development levels. Therefore, for different regions, key issues and measures adaptable to local condition should be prioritized and taken in order to realize regional balance development. (2) At provincial scale, there was also significant difference between each province and the spatial distribution of it was "high in the east, low in the west" in general. It meant that the capacity of natural resources attraction and conversion of east China was better than that of west China. The infrastructure level was the main factor ac- counting for the differences of material-based development levelsamong provinces. As a result, our government should make great efforts to improve infrastructure condition, especially the western part of China, so as to narrow the gap between the western part and the eastern part to realize the coordinated development within different regions and rapidly socio-economic development of China.展开更多
Sustainable development contributes to the economic and social advancement of construction projects. Ignoring sustainability during the cost estimating process associated with evaluation phase develops many problems o...Sustainable development contributes to the economic and social advancement of construction projects. Ignoring sustainability during the cost estimating process associated with evaluation phase develops many problems of conventional decision methodology used in construction industry in the most of developing countries. This research focuses on sustainability which is the key factor in all decision making in design and construction processes. Therefore, Iraqi construction industry should respond to sustainability as a leading indicator of its infrastructure rebuilding. The construction management and sustainability could help to manage the rebuilding of the destroyed public infrastructure during the disaster wars periods passed thru thirty years ago and also to modernize of private buildings and plants. Field study has been carried out by adopting personal interviews and questionnaires conducted with experts, experienced consultants and designers working in many design organizations. The data collected has been analyzed and the results obtained show a clear weakness in the field of sustainability understanding, practicing and implementation. Moreover, the design work in Iraq is suffering from a lack of scientific techniques and a lack in experience in the domain of sustainability field. This will take an integrated approach to study the impact of sustainability on construction management which encompasses both public and private sector perspectives for building and engineering construction, and the roles played by all the participants in the construction team (owners, contractors, design professionals, and other supporting professionals).展开更多
The present paper analyzes historically the relationship between carbon emission and economic development by different stages through adopting elastic decoupling methods and Tapio evaluation criteria along with a comp...The present paper analyzes historically the relationship between carbon emission and economic development by different stages through adopting elastic decoupling methods and Tapio evaluation criteria along with a comparison with the national Five Year Plans. The analysis shows that the influencing factors to the relationship between carbon emission and economy in China are different, and economic development and carbon emission have less connection in the recent 30 years of reform and opening-up in China. It is a difficult task to realize the promise that we will reduce carbon emission by 40%-50% in 2020 based on the data from historical experience and different expectations for economic development from economists. Through constructing the calcula- tion model of carbon emission intensity gap according to different development scenarios, the analysis shows that economic growth, infrastructure investment and further development of industrial-ization are the main drivers to the increase of carbon emission, technological progress, and particularly, the reduction of energy consumption is the primary means to reduce carbon emission in China. It is imperative to transform the economic growth pattern, and it is a grand task to perform and there is a long way to go for China to maintain economic growth and reduce carbon intensity.展开更多
The sustainable design approach presented in this paper supports an increased commitment to environmental stewardship and conservation, and results in an optimal balance of cost, environmental, societal, and human ben...The sustainable design approach presented in this paper supports an increased commitment to environmental stewardship and conservation, and results in an optimal balance of cost, environmental, societal, and human benefits while meeting the mission and function of the intended space structure. The aim of this paper is to develop the guidelines that could be applied in the design of a space structure in order to achieve the optimal overall lifetime performance of the space structure. Space structures are more than inanimate hunks of metal, glass and fabric. Every space structure that we design as structural engineers is like a child - a child that is conceived with a passionate vision of its form, structure and purpose; nurtured through the schematic design phase and the development of construction documents; and cared for during the labor pains of plan check corrections, requests for information, shop drawing review, and construction observation. Like children, our space structures mature, perform necessary functions during their lives, and eventually, grow old and die. The design of a sustainable space structure is a much more challenging and cross-disciplinary process than in the past and therefore it is necessary that the space structure is viewed as an integrated system and that all members of the design team work in a fully integrated fashion.展开更多
Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,part...Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,particularly for the waterlogging.In this study,both the urban issues emerged at the stage of rapid urbanization in China and the demands as well as problems of Sponge City construction related with the water issues were investigated,and the opportunities and challenges for the Sponge City construction in the future were also proposed.It was found that the current stormwater management focused on the construction of gray infrastructures(e.g.,drainage network and water tank) based on the fast discharge idea,which was costly and hard to catch up with the rapid expansion of city and its impervious surface,while green infrastructures(e.g.,river,lake and wetland)were ignored.Moreover,the current construction of Sponge City was still limited to low impacted development(LID) approach which was concentrated on source control measures without consideration of the critical functions of surrounding landscapes(i.e.,mountain,river,wetland,forest,farmland and lake),while application of the integrated urban water system approach and its supported technologies including municipal engineering,urban hydrology,environmental science,social science and ecoscape were relatively weak and needed to be improved.Besides,the lack of special Sponge City plan and demonstration area was also a considerable problem.In this paper,some perspectives on Good Sponge City Construction were proposed such as the point that idea of urban plan and construction should conform to the integral and systematic view of sustainable urban development.Therefore,both the basic theoretical research and the basic infrastructure construction such as monitoring system,drainage facility and demonstration area should be strengthened,meanwhile,the reformation and innovation in the urban water management system and the education system should also be urgently performed.The study was expected to provide a deeper thinking for the current Sponge City construction in China and to give some of suggestions for the future directions to urban plan and construction,as well as urban hydrology discipline.展开更多
This paper considers a variant of the classical facility location game called the uncapacitared facility location game with penalties (UFLGWP). Unlike the standard UFLG, each client in the UFLGWP is either assigned ...This paper considers a variant of the classical facility location game called the uncapacitared facility location game with penalties (UFLGWP). Unlike the standard UFLG, each client in the UFLGWP is either assigned to an open facility or rejected by paying a penalty. The authors propose a 3-approximate cross-monotonic cost-sharing method for the UFLGWP.展开更多
We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications (e.g. military, counter terrorist, and customs authorities in protecting ports and harbors), off...We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications (e.g. military, counter terrorist, and customs authorities in protecting ports and harbors), offshore production facilities or coastal approaches as well as various marine applications. In this paper, we propose a new approach to underwater sonar systems using the voltage-controlled liquid crystals and simple multiplexing method. The proposed method permits measurement of sound under water at multiple points along an optical fiber using the low cost components and standard single mode fiber, without complex interferometric measurement techniques, electronics or demodulation software.展开更多
Hydrogen is starting to be mentioned as an alternative fuel to replace the fossil fuel in future transportation applications due to its characteristics of zero greenhouse gas emission and high energy efficiency. Befor...Hydrogen is starting to be mentioned as an alternative fuel to replace the fossil fuel in future transportation applications due to its characteristics of zero greenhouse gas emission and high energy efficiency. Before hydrogen fuel and its facilities can be introduced to the public, relevant safety issues and its hazards must be assessed in order to avoid any chance of injury or loss. While a traditional risk assessment has difficulty in prioritizing the risk of failure modes, this paper proposes a new fuzzy-based risk evaluation technique which uses fuzzy value to prioritize the risk of various scenarios. In this study, the final risk of each failure modes was prioritized by using the MATLAB fuzzy logic tool box with a combination of two assessments. The first assessment was concerned with the criteria which affected the actual probability of occurrence. This assessment considered the availability of the standard that was applied to prevent the likelihood of the scenario occurring. On the other hand, the second assessment was focused on evaluating the consequence of the failure by taking into account the availability of detection and the complexity of the failure rather than only the severity of the scenarios. A total of 87 failure scenarios were identified using failure modes and effect analysis (FMEA) procedures on hydrogen refueling station models. Fuzzy-based assessments were performed through risk prioritizing various failure scenarios with a fuzzy value (0 to 1) and risk level (low, medium, and high) while a traditional risk assessment approach presented the risks only in forms of level (low, medium, and/or high). Availability of the fuzzy value enabled further prioritizing on the risk results that fell in the same level of risk. This study concluded that fuzzy-based risk evaluation is able to further prioritize the decisions when compared with a traditional risk assessment method.展开更多
Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reac- tor. Scattered neutrons from the object become a major disturbance and bring in artifacts and...Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reac- tor. Scattered neutrons from the object become a major disturbance and bring in artifacts and deviations in reconstruction re- suits, especially for hydrogenous material object. In this article, an iterative scattering correction method for fast neutron to- mography was proposed. In each loop of iteration the scattering component of the projections will be simulated by Mon- te-Carlo program MCNPX based on the previous reconstruction result and then it will be subtracted from original projections. The differences between scattering components at different perspectives were quantitatively evaluated and an average scatter- ing component image was used for all projections finally. Smooth and uniform slices with more clear edges were obtained and the new reconstructed attenuation coefficients are quite close to the real one compared to the results without scattering correc- tion, in which case the relative error of the reconstructed attenuation coefficients is about 10%-30%.展开更多
文摘A nonmetal transportation port with soft soil foundation of Tianjin New Harbor failed during construction in 1997. The soil properties and geological changes before and after landslide were in- vestigated by in situ test means. The stability of the slope was estimated with several calculation methods, such as the simplified Bishop method and the non-circle analysis method. According to the investigation and analysis results, the factors that may cause the slope failure can be deter- mined as follows: excessive excavating, violating the normal construction procedure, excessive pore water pressure during earlier piling and sudden water-level fluctuation in front of the slope. Measures to improve the soil foundation for reconstructing the port include strengthening the failed slope with vibro sand piles, filling up the crushed stone layer, dividing the excavation into four steps and driving piles by larger intervals. The port now has been successfully reconstructed and begun operation.
基金Financial support for this work,provided by the Key National Project(No.2008ZX05035)the State Science and Technology Support Program,the National Natural Science Foundation of China (Nos.40574057,40874054,40804026)the State Basic Research and Development Program of China(No.2007CB209406)
文摘Goafs are threats to safe mining.Their imaging effects or those of other complex geological bodies are often poor in conventional reflected wave images.Hence,accurate detection of goafs has become an important problem,to be solved with a sense of urgency.Based on scattering theory,we used an equivalent offset method to extract Common Scattering Point gathers,in order to analyze different scattering wave characteristics between Common Scattering Point and Common Mid Point gathers and to compare stack and migration imaging effects.Our research results show that the scattering wave imaging method is more efficient than the conventional imaging method and is therefore a more effective imaging method for detecting goafs and other complex geological bodies.It has important implications for safe mining procedures and infrastructures.
文摘This paper summarizes the approach, findings and evaluation methodology for a study that investigated the feasibility and potential impacts of street conversion options on traffic operations in downtown Birmingham, Alabama. Of particular interest were issues related to conversion of grid systems from one-way to two-way operations. Recommendations on the most promising design and control configurations for implementation are also provided. A literature review was performed that threw light on the issues and challenges associated with implementation of street conversions, and the available best practices. A comprehensive traffic impact analysis that ensued employed the SYNCHRO computer simulation model to represent current and future operations so as to assess the implications of two-way conversions at and around the test sites. Detailed realistic two-way operations scenarios were developed that considered geometric and right-of-way restrictions, the location of land uses that generate and/or attract vehicular and pedestrian traffic, connectivity with the street grid, and accessibility to nearby freeway facilities, as well as practical concerns.
基金supported by the National Research Foundation in Korea (NRF) through contract N-12-NM-IR19
文摘There are numerous information technology solutions including hardware and software. A company that provides the solution should have knowledge of the customer needs in the purpose of sailing strategy or upgrade policy. The needs are also directly connected to the user satisfaction. However, the users have respective points of view in the needs as well as they may not identify the requirements to improve the solution. SERVQUAL can be an appropriate method to define and measure the customer satisfaction for the information technology solutions. As a case study of the customer satisfaction, the modified SERVQUAL items and scoring method are applied to a cyber-infrastructure system named CyberL ab in Korea. The measurement results of user satisfaction for CyberL ab are provided to confirm that our proposed method performs as we intended. From the results, we can score the satisfaction level of users and identify their needs in the various aspects. The total user satisfaction level for CyberL ab is scored by 88.3.
基金supported by the National Natural Science Foundation of China under Grant No.60903166 the National High Technology Research and Development Program of China(863 Program) under Grants No.2012AA012506,No.2012AA012901,No.2012AA012903+9 种基金 Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20121103120032 the Humanity and Social Science Youth Foundation of Ministry of Education of China under Grant No.13YJCZH065 the Opening Project of Key Lab of Information Network Security of Ministry of Public Security(The Third Research Institute of Ministry of Public Security) under Grant No.C13613 the China Postdoctoral Science Foundation General Program of Science and Technology Development Project of Beijing Municipal Education Commission of China under Grant No.km201410005012 the Research on Education and Teaching of Beijing University of Technology under Grant No.ER2013C24 the Beijing Municipal Natural Science Foundation Sponsored by Hunan Postdoctoral Scientific Program Open Research Fund of Beijing Key Laboratory of Trusted Computing Funds for the Central Universities, Contract No.2012JBM030
文摘Network intrusion forensics is an important extension to present security infrastructure,and is becoming the focus of forensics research field.However,comparison with sophisticated multi-stage attacks and volume of sensor data,current practices in network forensic analysis are to manually examine,an error prone,labor-intensive and time consuming process.To solve these problems,in this paper we propose a digital evidence fusion method for network forensics with Dempster-Shafer theory that can detect efficiently computer crime in networked environments,and fuse digital evidence from different sources such as hosts and sub-networks automatically.In the end,we evaluate the method on well-known KDD Cup1999 dataset.The results prove our method is very effective for real-time network forensics,and can provide comprehensible messages for a forensic investigators.
文摘This article introduces three outstanding innovations, i.e. utilization of the steel casing for the piles to establish a construction platform for Sutong Bridge's large and deep-pile groups; 5000 ton steel cofferdam lowered as a whole and used as a protective structure against impact from ship collision; Permanent scour protection. This article also presents economical and reasonable design method for large bridge foundation and explains the significance of innovation and technical integration to large and complicated project construction based on the above theory.
基金supported by the project of Chinese Academy of Sciences (Grant no. KZCX2-YW-323)the Nation-al Population Development Strategy of China (Development Planning 2008-5)
文摘Regional development is a course of accumulation based on many factors, which is directly related to resources utilization and conversion. And material wealth production and accumulation embody the outcome of regional development. Thus, focusing on material wealth, regional development can be evaluated from resources and perspective of resources conversion. Taking the infrastructural level, transportation accessibility and economic development level into full account, the concept of "material-based development" was presented and the material-based development index (MDI) model was established. By using the MDI model, geographic information system technology and mathematic methods, this article then calculated MDI of each county and province of China in 2005 and systematically evaluated the material-based development of China at county and provincial scales, so as to bring some scientific references and policy-making supports to the population development function oriented zoning and population spatial distribution planning of China. The result showed that: (1) At county scale, the material-based development of counties within China in 2005 was significantly different, in which there were 1876 counties belonging to the mid-level material-based development and accounted for 78.10% of the total. The numbers of high-level and low-level counties were 144 and 382 and accounted for 6.00% and 15.90% respectively, demonstrating a spindle shape in general. The spatial distribution of material-based development was unbalanced, and it was much better in southeastern part of the line of "Daxinganling–Yinshan-Liupanshan–southeast edge of Qinghai–Tibet Plateau" than that of northwestern. Furthermore, there were also differences of the sub-index between different material-based development levels. Therefore, for different regions, key issues and measures adaptable to local condition should be prioritized and taken in order to realize regional balance development. (2) At provincial scale, there was also significant difference between each province and the spatial distribution of it was "high in the east, low in the west" in general. It meant that the capacity of natural resources attraction and conversion of east China was better than that of west China. The infrastructure level was the main factor ac- counting for the differences of material-based development levelsamong provinces. As a result, our government should make great efforts to improve infrastructure condition, especially the western part of China, so as to narrow the gap between the western part and the eastern part to realize the coordinated development within different regions and rapidly socio-economic development of China.
文摘Sustainable development contributes to the economic and social advancement of construction projects. Ignoring sustainability during the cost estimating process associated with evaluation phase develops many problems of conventional decision methodology used in construction industry in the most of developing countries. This research focuses on sustainability which is the key factor in all decision making in design and construction processes. Therefore, Iraqi construction industry should respond to sustainability as a leading indicator of its infrastructure rebuilding. The construction management and sustainability could help to manage the rebuilding of the destroyed public infrastructure during the disaster wars periods passed thru thirty years ago and also to modernize of private buildings and plants. Field study has been carried out by adopting personal interviews and questionnaires conducted with experts, experienced consultants and designers working in many design organizations. The data collected has been analyzed and the results obtained show a clear weakness in the field of sustainability understanding, practicing and implementation. Moreover, the design work in Iraq is suffering from a lack of scientific techniques and a lack in experience in the domain of sustainability field. This will take an integrated approach to study the impact of sustainability on construction management which encompasses both public and private sector perspectives for building and engineering construction, and the roles played by all the participants in the construction team (owners, contractors, design professionals, and other supporting professionals).
文摘The present paper analyzes historically the relationship between carbon emission and economic development by different stages through adopting elastic decoupling methods and Tapio evaluation criteria along with a comparison with the national Five Year Plans. The analysis shows that the influencing factors to the relationship between carbon emission and economy in China are different, and economic development and carbon emission have less connection in the recent 30 years of reform and opening-up in China. It is a difficult task to realize the promise that we will reduce carbon emission by 40%-50% in 2020 based on the data from historical experience and different expectations for economic development from economists. Through constructing the calcula- tion model of carbon emission intensity gap according to different development scenarios, the analysis shows that economic growth, infrastructure investment and further development of industrial-ization are the main drivers to the increase of carbon emission, technological progress, and particularly, the reduction of energy consumption is the primary means to reduce carbon emission in China. It is imperative to transform the economic growth pattern, and it is a grand task to perform and there is a long way to go for China to maintain economic growth and reduce carbon intensity.
文摘The sustainable design approach presented in this paper supports an increased commitment to environmental stewardship and conservation, and results in an optimal balance of cost, environmental, societal, and human benefits while meeting the mission and function of the intended space structure. The aim of this paper is to develop the guidelines that could be applied in the design of a space structure in order to achieve the optimal overall lifetime performance of the space structure. Space structures are more than inanimate hunks of metal, glass and fabric. Every space structure that we design as structural engineers is like a child - a child that is conceived with a passionate vision of its form, structure and purpose; nurtured through the schematic design phase and the development of construction documents; and cared for during the labor pains of plan check corrections, requests for information, shop drawing review, and construction observation. Like children, our space structures mature, perform necessary functions during their lives, and eventually, grow old and die. The design of a sustainable space structure is a much more challenging and cross-disciplinary process than in the past and therefore it is necessary that the space structure is viewed as an integrated system and that all members of the design team work in a fully integrated fashion.
基金supported by the National Natural Science Foundation of China(Grant No.41571028)Key Programs of the Chinese Academy of Sciences(Grant No.KFZD-SW-301)
文摘Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes.The construction of Sponge City is an effective approach to solving the urban water issues,particularly for the waterlogging.In this study,both the urban issues emerged at the stage of rapid urbanization in China and the demands as well as problems of Sponge City construction related with the water issues were investigated,and the opportunities and challenges for the Sponge City construction in the future were also proposed.It was found that the current stormwater management focused on the construction of gray infrastructures(e.g.,drainage network and water tank) based on the fast discharge idea,which was costly and hard to catch up with the rapid expansion of city and its impervious surface,while green infrastructures(e.g.,river,lake and wetland)were ignored.Moreover,the current construction of Sponge City was still limited to low impacted development(LID) approach which was concentrated on source control measures without consideration of the critical functions of surrounding landscapes(i.e.,mountain,river,wetland,forest,farmland and lake),while application of the integrated urban water system approach and its supported technologies including municipal engineering,urban hydrology,environmental science,social science and ecoscape were relatively weak and needed to be improved.Besides,the lack of special Sponge City plan and demonstration area was also a considerable problem.In this paper,some perspectives on Good Sponge City Construction were proposed such as the point that idea of urban plan and construction should conform to the integral and systematic view of sustainable urban development.Therefore,both the basic theoretical research and the basic infrastructure construction such as monitoring system,drainage facility and demonstration area should be strengthened,meanwhile,the reformation and innovation in the urban water management system and the education system should also be urgently performed.The study was expected to provide a deeper thinking for the current Sponge City construction in China and to give some of suggestions for the future directions to urban plan and construction,as well as urban hydrology discipline.
基金supported by the National Natural Science Foundation of China under Grant Nos.60773185 and 11071268Program for Beijing Excellent Talents
文摘This paper considers a variant of the classical facility location game called the uncapacitared facility location game with penalties (UFLGWP). Unlike the standard UFLG, each client in the UFLGWP is either assigned to an open facility or rejected by paying a penalty. The authors propose a 3-approximate cross-monotonic cost-sharing method for the UFLGWP.
文摘We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications (e.g. military, counter terrorist, and customs authorities in protecting ports and harbors), offshore production facilities or coastal approaches as well as various marine applications. In this paper, we propose a new approach to underwater sonar systems using the voltage-controlled liquid crystals and simple multiplexing method. The proposed method permits measurement of sound under water at multiple points along an optical fiber using the low cost components and standard single mode fiber, without complex interferometric measurement techniques, electronics or demodulation software.
基金Project (No. D000023-16001) supported by the Malaysian Ministry of Higher Education (MOHE) High Impact Research Foundation
文摘Hydrogen is starting to be mentioned as an alternative fuel to replace the fossil fuel in future transportation applications due to its characteristics of zero greenhouse gas emission and high energy efficiency. Before hydrogen fuel and its facilities can be introduced to the public, relevant safety issues and its hazards must be assessed in order to avoid any chance of injury or loss. While a traditional risk assessment has difficulty in prioritizing the risk of failure modes, this paper proposes a new fuzzy-based risk evaluation technique which uses fuzzy value to prioritize the risk of various scenarios. In this study, the final risk of each failure modes was prioritized by using the MATLAB fuzzy logic tool box with a combination of two assessments. The first assessment was concerned with the criteria which affected the actual probability of occurrence. This assessment considered the availability of the standard that was applied to prevent the likelihood of the scenario occurring. On the other hand, the second assessment was focused on evaluating the consequence of the failure by taking into account the availability of detection and the complexity of the failure rather than only the severity of the scenarios. A total of 87 failure scenarios were identified using failure modes and effect analysis (FMEA) procedures on hydrogen refueling station models. Fuzzy-based assessments were performed through risk prioritizing various failure scenarios with a fuzzy value (0 to 1) and risk level (low, medium, and high) while a traditional risk assessment approach presented the risks only in forms of level (low, medium, and/or high). Availability of the fuzzy value enabled further prioritizing on the risk results that fell in the same level of risk. This study concluded that fuzzy-based risk evaluation is able to further prioritize the decisions when compared with a traditional risk assessment method.
基金supported by the Academic Exchange Fund of Peking University Graduate Schoolthe National Basic Research Program of China(Grant No.2010CB833106)
文摘Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reac- tor. Scattered neutrons from the object become a major disturbance and bring in artifacts and deviations in reconstruction re- suits, especially for hydrogenous material object. In this article, an iterative scattering correction method for fast neutron to- mography was proposed. In each loop of iteration the scattering component of the projections will be simulated by Mon- te-Carlo program MCNPX based on the previous reconstruction result and then it will be subtracted from original projections. The differences between scattering components at different perspectives were quantitatively evaluated and an average scatter- ing component image was used for all projections finally. Smooth and uniform slices with more clear edges were obtained and the new reconstructed attenuation coefficients are quite close to the real one compared to the results without scattering correc- tion, in which case the relative error of the reconstructed attenuation coefficients is about 10%-30%.