Estimating projects duration in uncertain environments: Monte Carlo simulations strike back

PERT (Program Evaluation and Review Technique), developed in the 1950’s, represented the first attempt to incorporate uncertainty in project scheduling. Despite some weaknesses, it is still widely used in project management mostly thanks to the simplicity of its algorithm in operating on activity network diagrams. Today the increasing complexity of projects requires new techniques and the increasing availability of computer power have not brought project simulation into common usage as expected. Although several reviews assert that simulative approach has already superseded PERT when coping with uncertain environment; the reason why it is not diffused is that simulations require a too long computing time. In this paper we show through an algorithm and experimental results that the computational time, historically the major drawback of Monte Carlo simulations, is definitely minimum thanks also to the computational power available nowadays. We present results of an efficient program made of few lines of code and able to compute the completion time of a network activity diagram with 100.000 activities and about 50.000.000 precedence constraints between them

Estimating projects duration in uncertain environments: Monte Carlo simulations strike back

PERT (Program Evaluation and Review Technique), developed in the 1950’s, represented the first attempt to incorporate uncertainty in project scheduling. Despite some weaknesses, it is still widely used in project management mostly thanks to the simplicity of its algorithm in operating on activity network diagrams. Today the increasing complexity of projects requires new techniques and the increasing availability of computer power have not brought project simulation into common usage as expected. Although several reviews assert that simulative approach has already superseded PERT when coping with uncertain environment; the reason why it is not diffused is that simulations require a too long computing time. In this paper we show through an algorithm and experimental results that the computational time, historically the major drawback of Monte Carlo simulations, is definitely minimum thanks also to the computational power available nowadays. We present results of an efficient program made of few lines of code and able to compute the completion time of a network activity diagram with 100.000 activities and about 50.000.000 precedence constraints between them

Applying fuzzy PERT in cycle time management for supply chain system

As the fast technology evolution and the globalization trend, the competition among businesses transform into supply chain network gradually. However, the operation performance of the supply chain network influenced by many uncertain factors. These uncertain influence factors include the demand of the customer, the response time of delivery, operation lead time, stock level and cost. Under foregoing conditions, enterprises cannot control the variations in actual environment precisely and satisfy customers’ requirements. Therefore, the linguistic variables are used to express these uncertainties in this paper. First, this paper presents a procedure to transform the operation processes of the supply chain network into a diagram to indicate the activities among members of supply chain. Second, combining fuzzy set theory with the program evaluation and review technique (PERT) to estimate the cycle time of supply chain system. According to the fuzzy PERT model, we can calculate the cycle time and find out the critical path of a supply chain system. Furthermore, we can compute the possibility of the order fulfillment of a supply chain system. Finally, a numerical simulation is presented to illustrate the procedure of this proposed model

Review on bio-based plastic for future applications

This paper reviews the future applications of bio-based plastics. Most plastics are made through petrochemical processes. In other words, they start out as the chemical byproducts of oil refining, which are turned into a variety of plastics through chemical processes that form long molecular chains known as polymers. These polymers give plastics their structure. Bioplastics are biodegradable materials that come from renewable sources and can be used to reduce the problem of plastic waste that is suffocating the planet and contaminating the environment. The advantages of using bioplastics are bioplastics won’t leach chemicals into food, non- toxic and offer a zero waste end life options. Bioplastics can be recycled with conventional plastics to produce a great material for food packaging. It also has a socio�economic benefit that often have a positive impact on the consumers who are increasingly becoming aware of environmental issues. As conclusion, it is proven that bioplastics give promising future to cleaner and safer world

Time Reduction for Completion of a Civil Engineering Construction Using Fuzzy Clustering Techniques

In the civil engineering field, there are usually unexpected troubles that can cause delays during execution. This situation involves numerous variables (resource number, execution time, costs, working area availability, etc.), mutually dependent, that complicate the definition of the problem analytical model and the related resolution. Consequently, the decision-maker may avoid rational methods to define the activities that could be conveniently modified, relying only on his personal experience or experts’ advices. In order to improve this kind of decision from an objective point of view, the authors analysed the operation correction using a data mining technique, called Fuzzy Clustering. This allows the analysts to represent complex real scenarios and classify the various activities according to their influence on the reduction of the total execution time. The proposed procedure provides positive results that are also in compliance with significant operational constraints, such as the control of costs and areas needed by the workers to perform the tasks. Finally, it is possible to increase the input variable number preserving the algorithm simplicity and avoiding lacks of accuracy in the final numerical outcomes

Supply Chain

Traditionally supply chain management has meant factories, assembly lines, warehouses, transportation vehicles, and time sheets. Modern supply chain management is a highly complex, multidimensional problem set with virtually endless number of variables for optimization. An Internet enabled supply chain may have just-in-time delivery, precise inventory visibility, and up-to-the-minute distribution-tracking capabilities. Technology advances have enabled supply chains to become strategic weapons that can help avoid disasters, lower costs, and make money. From internal enterprise processes to external business transactions with suppliers, transporters, channels and end-users marks the wide range of challenges researchers have to handle. The aim of this book is at revealing and illustrating this diversity in terms of scientific and theoretical fundamentals, prevailing concepts as well as current practical applications

Newark College of Engineering Graduate Programs 1973-74 Academic Year

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