Since the construction industry has been adopting Building Information Modeling(BIM)as the standard practice for design,engineering,and fabrication in the recent decade,many Construction Management(CM)programs at U.S....Since the construction industry has been adopting Building Information Modeling(BIM)as the standard practice for design,engineering,and fabrication in the recent decade,many Construction Management(CM)programs at U.S.universities have started to introduce BIM for cost estimating in their curriculum.Although considered as the fifth dimension beyond 3D and schedule,BIM for cost estimating in many cases is still used merely as an alternative model-based quantity takeoff method to the traditional plan-based approach.The disconnection between automated quantity takeoff and cost estimating,however,still exists,and the benefits of the BIM process in a project life cycle can not be fully understood by CM students without realizing its impact in the preconstruction phase.To bridge these gaps in a CM curriculum,an Advanced Cost Estimating course for CM programs has been developed that focuses on integrating BIM in both the takeoff and estimating process.The new course streamlines the connection between model-based quantity takeoff and cost estimating with the help of a combination of multiple construction software programs.Through the integration between the software,quantity data from a BIM model can be seamlessly transferred to a construction cost database for bid pricing and reporting.This paper presents the development of the new Advanced Cost Estimating course as a case study,including its objectives,layout,and assessment methods,and provides empirical and valuable insights on how to integrate BIM in a cost estimating course for a CM curriculum.展开更多
On the basis of the analysis of classical stock model, according to the limitation of the model, the article puts forward the revision of classical model and enforces the applicability of the stock model.
Petroleum products contamination is a world-wide problem that threatens polluting groundwater and surface water systems. However, the problem is not only large-scale in scope when viewed from a case-by-case basis. Man...Petroleum products contamination is a world-wide problem that threatens polluting groundwater and surface water systems. However, the problem is not only large-scale in scope when viewed from a case-by-case basis. Many fueling, construction, agricultural, and industrial activities result in the problem of managing smaller quantities of these soils from an ecological safety perspective. Landfilling has been the disposal method of choice in the US;however, this option is becoming economically prohibitive and it does not really offer a true degradation fate for the pollutants. This study focused on the proving of an innovative biocell design that afforded a high level of petroleum degradation within a simple and cost effective design. Additionally, the design offered a remediation solution for sites not easily accessed. Soil contaminated with both diesel fuel and gasoline collected from a former filling station was used in this on-site remediation case study. Rapid biodegradation of the petroleum products were observed at the initiation of the study with rates leveling off as the study progressed with the final total petroleum hydrocarbon concentration being 10 mg/kg at Day 90. Oxygen uptake rates were monitored and found to nicely track both microbial activity and pollutant removal dynamics. The biocell design met all expectations by being effective, yet simple to build and operate.展开更多
异常事件可能导致供应链中断或订单延迟,由此形成的异常采购提前期(procurement lead time,PLT)往往比正常的PLT要长。为了应对异常状态,企业需要权衡成本和服务水平以制定最优的订货策略。较高水平的订货批量会降低订货次数,形成稳健...异常事件可能导致供应链中断或订单延迟,由此形成的异常采购提前期(procurement lead time,PLT)往往比正常的PLT要长。为了应对异常状态,企业需要权衡成本和服务水平以制定最优的订货策略。较高水平的订货批量会降低订货次数,形成稳健的订货策略;较低水平的订货批量可以形成灵活的订货策略。本研究将PLTs相关性定义为异常与正常PLTs差异乘数项的均值,基于两个相关PLTs构建零售商库存决策的成本服务均衡模型,研究订货批量决策。研究结果表明,当周期服务水平较高时,PLTs相关性变化并不会影响企业的订货策略;当周期服务水平小于某一值时,PLTs相关性增大,企业倾向于较高的订货批量,从而形成稳健的订货策略。同时,PLT波动对订货批量影响存在多个服务水平阈值,在不同的服务水平范围内,企业可采取的最佳订货策略不同。这个发现与独立PLTs假设中,PLT波动对订货批量影响只有一个服务水平阈值有明显区别。随着PLT波动增大,企业会采取与独立PLTs条件下不同的对策。展开更多
文摘Since the construction industry has been adopting Building Information Modeling(BIM)as the standard practice for design,engineering,and fabrication in the recent decade,many Construction Management(CM)programs at U.S.universities have started to introduce BIM for cost estimating in their curriculum.Although considered as the fifth dimension beyond 3D and schedule,BIM for cost estimating in many cases is still used merely as an alternative model-based quantity takeoff method to the traditional plan-based approach.The disconnection between automated quantity takeoff and cost estimating,however,still exists,and the benefits of the BIM process in a project life cycle can not be fully understood by CM students without realizing its impact in the preconstruction phase.To bridge these gaps in a CM curriculum,an Advanced Cost Estimating course for CM programs has been developed that focuses on integrating BIM in both the takeoff and estimating process.The new course streamlines the connection between model-based quantity takeoff and cost estimating with the help of a combination of multiple construction software programs.Through the integration between the software,quantity data from a BIM model can be seamlessly transferred to a construction cost database for bid pricing and reporting.This paper presents the development of the new Advanced Cost Estimating course as a case study,including its objectives,layout,and assessment methods,and provides empirical and valuable insights on how to integrate BIM in a cost estimating course for a CM curriculum.
文摘On the basis of the analysis of classical stock model, according to the limitation of the model, the article puts forward the revision of classical model and enforces the applicability of the stock model.
文摘Petroleum products contamination is a world-wide problem that threatens polluting groundwater and surface water systems. However, the problem is not only large-scale in scope when viewed from a case-by-case basis. Many fueling, construction, agricultural, and industrial activities result in the problem of managing smaller quantities of these soils from an ecological safety perspective. Landfilling has been the disposal method of choice in the US;however, this option is becoming economically prohibitive and it does not really offer a true degradation fate for the pollutants. This study focused on the proving of an innovative biocell design that afforded a high level of petroleum degradation within a simple and cost effective design. Additionally, the design offered a remediation solution for sites not easily accessed. Soil contaminated with both diesel fuel and gasoline collected from a former filling station was used in this on-site remediation case study. Rapid biodegradation of the petroleum products were observed at the initiation of the study with rates leveling off as the study progressed with the final total petroleum hydrocarbon concentration being 10 mg/kg at Day 90. Oxygen uptake rates were monitored and found to nicely track both microbial activity and pollutant removal dynamics. The biocell design met all expectations by being effective, yet simple to build and operate.
文摘异常事件可能导致供应链中断或订单延迟,由此形成的异常采购提前期(procurement lead time,PLT)往往比正常的PLT要长。为了应对异常状态,企业需要权衡成本和服务水平以制定最优的订货策略。较高水平的订货批量会降低订货次数,形成稳健的订货策略;较低水平的订货批量可以形成灵活的订货策略。本研究将PLTs相关性定义为异常与正常PLTs差异乘数项的均值,基于两个相关PLTs构建零售商库存决策的成本服务均衡模型,研究订货批量决策。研究结果表明,当周期服务水平较高时,PLTs相关性变化并不会影响企业的订货策略;当周期服务水平小于某一值时,PLTs相关性增大,企业倾向于较高的订货批量,从而形成稳健的订货策略。同时,PLT波动对订货批量影响存在多个服务水平阈值,在不同的服务水平范围内,企业可采取的最佳订货策略不同。这个发现与独立PLTs假设中,PLT波动对订货批量影响只有一个服务水平阈值有明显区别。随着PLT波动增大,企业会采取与独立PLTs条件下不同的对策。
