The wide application of information and communication technologies （ICTs） has been argued to be critical to spatial transformation of firms. Recent advances in the studies along this line have challenged traditional...The wide application of information and communication technologies （ICTs） has been argued to be critical to spatial transformation of firms. Recent advances in the studies along this line have challenged traditional location theory. The existing literature, however, focuses mainly on the impacts of ICTs on Iocational conditions and industrial spatial distribution. The dynamics behind such changes have not yet been given sufficient attention by geographers. Given this background, this paper investigates the impact of new ICTs on traditional location theory and the dynamics of industrial re-location that are enabled by new ICTs, based on data collected from an investigation of 178 firms. The paper argues that the application of new ICTs has been a key location factor in the information age, and that the time-cost is becoming critical to the spatial organization of firms, particularly as a result of a shorter product life and mass customization, among other dynamics.展开更多
随着OGSA(open grid service architecture)的提出,在网格环境中,如何进行服务的选择是一个热点问题.对于DAG(directed acyclic gragh)描述的网格工作流模型,考虑时间和费用两个Qos(quality of service)参数,即满足用户截止期的前提下,...随着OGSA(open grid service architecture)的提出,在网格环境中,如何进行服务的选择是一个热点问题.对于DAG(directed acyclic gragh)描述的网格工作流模型,考虑时间和费用两个Qos(quality of service)参数,即满足用户截止期的前提下,为工作流选择尽可能便宜的服务.对于一般遗传算法的求解问题时出现的早熟和退化现象,采用了免疫算子和遗传算子相结合的免疫遗传算法来进行搜索全局解,并且加入了自适应遗传交叉算子和疫苗提取来提高搜索能力.仿真试验证明文章的算法具有较好的解空间搜索性能.展开更多
Job-shop scheduling problem with discretely controllable processing times (JSP-DCPT) is modeled based on the disjunctive graph, and the formulation of JSP-DCPT is presented. A three-step decomposition approach is prop...Job-shop scheduling problem with discretely controllable processing times (JSP-DCPT) is modeled based on the disjunctive graph, and the formulation of JSP-DCPT is presented. A three-step decomposition approach is proposed so that JSP-DCPT can be handled by solving a job-shop scheduling problem (JSP) and a series of discrete time-cost tradeoff problems. To simplify the decomposition approach, the time-cost phase plane is introduced to describe tradeoffs of the discrete time-cost tradeoff problem, and an extreme mode-based set dominant theory is elaborated so that an upper bound is determined to cut discrete time-cost tradeoff problems generated by using the proposed decomposition approach. An extreme mode-based set dominant decomposition algorithm (EMSDDA) is then proposed. Experimental simulations for instance JSPDCPT_FT10, which is designed based on a JSP benchmark FT10, demonstrate the effectiveness of the proposed theory and the decomposition approach.展开更多
It is very difficult to estimate exact values of time and cost of an activity in project scheduling process because many uncertain factors, such as weather, productivity level, human factors etc. , dynamically affect ...It is very difficult to estimate exact values of time and cost of an activity in project scheduling process because many uncertain factors, such as weather, productivity level, human factors etc. , dynamically affect them during project implementation process. A GAs-based fully fuzzy optimal time-cost trade-off model is presented based on fuzzy sets and genetic algorithms (GAs). In tihs model all parameters and variables are characteristics by fuzzy numbers. And then GAs is adopted to search for the optimal solution to this model. The method solves the time-cost trade-off problems under an uncertain environment and is proved practicable through a giving example in ship building scheduling.展开更多
In this paper,a new optimizing model has been designed to the linear programming model for time-cost trade-off in networks by using the characters of network construction. The model cuts down nearly the half number of...In this paper,a new optimizing model has been designed to the linear programming model for time-cost trade-off in networks by using the characters of network construction. The model cuts down nearly the half number of constraints then enlarges the extent of the application to network optindzation.展开更多
基金National Natural Science Foundation of China, No.41001081 No.41125005 Key Program of Chinese Academy of Sciences, No.KZZD-EW-06
文摘The wide application of information and communication technologies （ICTs） has been argued to be critical to spatial transformation of firms. Recent advances in the studies along this line have challenged traditional location theory. The existing literature, however, focuses mainly on the impacts of ICTs on Iocational conditions and industrial spatial distribution. The dynamics behind such changes have not yet been given sufficient attention by geographers. Given this background, this paper investigates the impact of new ICTs on traditional location theory and the dynamics of industrial re-location that are enabled by new ICTs, based on data collected from an investigation of 178 firms. The paper argues that the application of new ICTs has been a key location factor in the information age, and that the time-cost is becoming critical to the spatial organization of firms, particularly as a result of a shorter product life and mass customization, among other dynamics.
文摘随着OGSA(open grid service architecture)的提出,在网格环境中,如何进行服务的选择是一个热点问题.对于DAG(directed acyclic gragh)描述的网格工作流模型,考虑时间和费用两个Qos(quality of service)参数,即满足用户截止期的前提下,为工作流选择尽可能便宜的服务.对于一般遗传算法的求解问题时出现的早熟和退化现象,采用了免疫算子和遗传算子相结合的免疫遗传算法来进行搜索全局解,并且加入了自适应遗传交叉算子和疫苗提取来提高搜索能力.仿真试验证明文章的算法具有较好的解空间搜索性能.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51075337, 50705076, 50705077)the Natural Sci-ence Basic Research Plan in Shaanxi Province of China (Grant No. 2009JQ9002)
文摘Job-shop scheduling problem with discretely controllable processing times (JSP-DCPT) is modeled based on the disjunctive graph, and the formulation of JSP-DCPT is presented. A three-step decomposition approach is proposed so that JSP-DCPT can be handled by solving a job-shop scheduling problem (JSP) and a series of discrete time-cost tradeoff problems. To simplify the decomposition approach, the time-cost phase plane is introduced to describe tradeoffs of the discrete time-cost tradeoff problem, and an extreme mode-based set dominant theory is elaborated so that an upper bound is determined to cut discrete time-cost tradeoff problems generated by using the proposed decomposition approach. An extreme mode-based set dominant decomposition algorithm (EMSDDA) is then proposed. Experimental simulations for instance JSPDCPT_FT10, which is designed based on a JSP benchmark FT10, demonstrate the effectiveness of the proposed theory and the decomposition approach.
基金Supported by the National High-Tech. R&D Program for CIMS (NO. 2003AA414060).
文摘It is very difficult to estimate exact values of time and cost of an activity in project scheduling process because many uncertain factors, such as weather, productivity level, human factors etc. , dynamically affect them during project implementation process. A GAs-based fully fuzzy optimal time-cost trade-off model is presented based on fuzzy sets and genetic algorithms (GAs). In tihs model all parameters and variables are characteristics by fuzzy numbers. And then GAs is adopted to search for the optimal solution to this model. The method solves the time-cost trade-off problems under an uncertain environment and is proved practicable through a giving example in ship building scheduling.
文摘In this paper,a new optimizing model has been designed to the linear programming model for time-cost trade-off in networks by using the characters of network construction. The model cuts down nearly the half number of constraints then enlarges the extent of the application to network optindzation.
