Program Evaluation and Review Technique (PERT) in Construction Schedule Risk Assessment

Construction project scheduling is one of the most critical factors for project success measurement.Not only for the project planning but for construction process management,the scheduling is the basic tool for communication between the owner and the project manager.By developing the schedule before the project starts,the owner knows in advance that the expected timeline of the project.By preparing construction process scheduling,the owner and general contractor can better manage the subcontractors,sub-trades progress,materials storage and deliveries,labors schedule and equipment set up which will eventually save time,money and hassle.Basically,Critical Path Method(CPM) is commonly used in the construction industry.CPM is a deterministic method that assumes that through the network,there is at least one path that determines the project duration and that the path is the critical path.CPM does not consider the uncertainty in the activities;rather it assumes that each activity can be finished in the given situation.Program Evaluation and Review Technique(PERT) is a stochastic technique which is based on the assumption that the duration of a single activity can be described by a probability density function.PERT takes into account the uncertainty during the construction process and has been created out of the need to plan,schedule and control complex projects with many uncertainties.The PERT approach is stated in some books and papers,but there is no deep investigation on the application in the schedule risk assessment.This paper investigates the PERT work process and takes a valuable try on the construction schedule risk assessment by using case studies.The utilization in the estimate the construction liquidated damage with the uncertainties is performed,which also can be used in the insurance company to calculate the insurance premium.     

Economic humidity control: an alternative to reheat

Heat pipe technology will have a significant impact on the power consumption of many manufacturing industries, the installation costs of new or replacement air conditioning systems, and on electric utility peak demands.     

用光控制大脑

埃德·博伊登(Ed Boyden)在麻省理工学院实验室里的设备极其多样,有一些分析和合成基因的机器,一台3D打印机,一个可以在金属块上进行雕刻的激光切割机,一些培养并研究细菌,植物和真菌的设备,一台制备超薄脑切片的机器,分析电子电路的工具,一套高清晰度成像设备.但博伊登最爱炫耀的,是一个看上去又小又丑陋的东西,像一颗毛茸茸的小塑料牙齿.实际上,它里面装有十多根不同长度的短光纤,每根的一端固定着一个发光二极管(LED).比如说,当这个牙被植进老鼠的大脑,每根LED可以将光传输到不同的位置.使用这个设备,博伊登可以控制老鼠的各个行为.     

Sales and marketing's partnership role in class A MRP II (material requirements planning)

As the material and requirements planning (MRP) II process has evolved, many companies have discovered that the process is greatly enhanced when the entire business participates. The sales and operations planning process is the forum for the businesswide decisions concerning sales, production, and inventory. Sales and marketing must be integral parts of these decision-making activities.     

AIDS is your business

If your company operates in a developing country, AIDS is your business. While Africa has received the most attention, AIDS is also spreading swiftly in other parts of the world. Russia and Ukraine had the fastest-growing epidemics last year, and many experts believe China and India will suffer the next tidal wave of infection. Why should executives be concerned about AIDS? Because it is destroying the twin rationales of globalization strategy-cheap labor and fast-growing markets--in countries where people are heavily affected by the epidemic. Fortunately, investments in programs that prevent infection and provide treatment for employees who have HIV/AIDS are profitable for many businesses--that is, they lead to savings that outweigh the programs' costs. Due to the long latency period between HIV infection and the onset of AIDS symptoms, a company is not likely to see any of the costs of HIV/AIDS until five to ten years after an employee is infected. But executives can calculate the present value of epidemic-related costs by using the discount rate to weigh each cost according to its expected timing. That allows companies to think about expenses on HIV/AIDS prevention and treatment programs as investments rather than merely as costs. The authors found that the annual cost of AIDS to six corporations in South Africa and Botswana ranged from 0.4% to 5.9% of the wage bill. All six companies would have earned positive returns on their investments if they had provided employees with free treatment for HIV/AIDS in the form of highly active antiretroviral therapy (HAART), according to the mathematical model the authors used. The annual reduction in the AIDS "tax" would have been as much as 40.4%. The authors' conclusion? Fighting AIDS not only helps those infected; it also makes good business sense.     

Parental Compensatory Behaviors and Early Child Health Outcomes in Cebu, Philippines()

A dynamic optimization model of parents choosing investments in their children's health motivates an empirical model of parents' choices of health inputs for their children and the impacts of these decisions on their children's subsequent health. Estimates of the child health input demand functions and the child health production functions from the Cebu Longitudinal Health and Nutrition Survey accord with the prediction that optimizing behavior results in higher levels of aggregate child health. Observable parental behaviors respond to the physical developmental status of their children. These parental responses appear to yield large and statistically significant improvements in children's early physiological outcomes. However, because some health inputs choices are not observable, it is impossible to ascertain whether these measured effects are due solely to variations in the observed input choices.     

MRO新兴市场

尽管全球经济下滑,中国、印度、中东的经济仍在快速增长。人们关注的兴致在于,这些地区将来会不会刹车。     

The economic law of population distribution and migration

"The economic law of population distribution and migration has been studied chiefly based on the Chinese situation. The distribution and development of productive forces decide the distribution and migration of population, and in turn, the latter influences the former. The population distributions in three different stages of social development, namely agricultural, industrial and information society, are described. A new concept in population economics is introduced, i.e. population economic density, which is different from the concept of population density. The formula of population economic density is P(population)/R(resources). Many kinds of migration are analysed, and it is believed that the main efficient cause of migration is economy."