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2，The Exchange Problem between Project Date and Project Cost The total cost of Project is making up by direct costs and indirect costs (Wang, 2001). Generally speaking, direct costs such as construction cost and the use amount of resources Increasing when Project date cut down, indirect costs such as management and safety will reduce when Project date cut down. The Exchange Problem between Project date and Project cost is to find the lowest point of 代写留学生论文cost and the Schedule of net plan in the context of Project period meet the requirements. Fig.
2.1shows the Relation between Date and Cost. Point A means the Project date when the cost is the lowest. [pic] Figure
2.2 Relations between Date and Cost Source: Shou 2004 The substance of the Exchange Problem between Project date and Project cost is to choose the best combination between date and cost to make the rush rate lowest in the net plan (Shou, 2004). The theory contains two assumptions: all the direct costs of the work in net plan have Non- increasing linear relationship, the cost rate is P; the relation between indirect costs and Project date is Single increasing linear relationship, q is the indirect costs rate.We often uses optimization such as Progressive method, Reductionism, Labelling, Linear Programming. We always use Progressive method in the schedule management of project, It is used in the base that Various activities adopt normal time and cost plan, then use the duration of key activities and cost relationship as basis. We must constantly adjust network plan after considering the Possibility of Shortening the critical activity duration and the constraint relations of time difference between non-critical activities to get a Series of project schedule.
2.7.4 The Problem of Max-NPV The Problem of Max-NPV Considers the network optimization program from the financial side (Jonathan P.Pinder, 1996). The problem regards maximizing the net present value as optimization objective for the project's progress; it emphasizes not resource balance and the shortest project date but revenue maximization and shorter project date and higher resource utilization. The early studies of Max-NPV use approximate linear programming to solve the problem, Later there will be some analysis of Algorithms such as branch bound method and many heuristic algorithms. Heuristic algorithms have been the most important method to solve the problem at present. PATE 3
2.8 Deficiency of the Existing Research In this paper (Zhang, 2005), it tells us deficiency of the existing research. It can be summed up in three sub problem. The first one is deficiency of the objective function. As objective function directly reflect optimized objectives, which is reasonable or not will directly affect the reality of the research. The existing target basically has the following three deficiencies:Firstly, it is not in accord with the enterprises which seek for profit maximization;Secondly, it does not consider the time value of money and the dynamic optimization of question in the whole project cycle;Thirdly, it does not consider the owner's payment and the rewards and punishment. In practice, the construction enterprises think about data-cost which is closely related the owner's payment. The second one is no consideration of resource constraints or only a single resource constraint (Zhang, 2005). In practice, the consumption of resources occupied most of construction investment. Any project construction needs many resources. Decreasing the construction period is realized by increasing resource allocation, so resource constraints are inevitable. All activities start to use a certain resource simultaneously that will cause a bottleneck. Increasing resources or extending the working time of the resources will decrease the construction period. So the resource is an essential factor in a network plan optimization. The third one is the simplification execution mode (Zhang, 2005). In practical engineering, construction units according to the progress of the construction decide how much of the facility resources?the additional cost and the length of construction period. Then determines the extended or shorten the construction activities, which mean that activities have a variety of execution modes. Construction unit choose a reasonable mode to perform the activities according to the practice situation. Single mode makes the research results different form actual ones. 3. METHODOLOGY 3.0 Introduction Within this Chapter the author will justify and identify how he plans to carry on the research with a consideration for the interrelated method. In choosing specific research methods it is significant to justify the theoretical philosophy and perspective that our choice of research is based on. Crotty (1998) showed that a researcher needs to identify the methods and methodologies employed which "reaches into the assumptions about the reality" we adopt into our research.
3.1 Research Philosophy The philosophy used in this paper by the author provides a framework on how the entire research process is planned and carried out. In determining the research philosophy used we must illustrate what is knowledge and how it is got firstly, these questions are related to the Epistemological viewpoint of the researcher, Epistemological is identified as being concerned with if the natural sciences or social sciences can give us with the necessary knowledge in our chosen theme (Bryman and Bell ,2003).
3.1.1 Positivism or Interpretivism The primary Epistemological philosophies identified by (Collis and Hussey 2003; Bryman and Bell 2003) are that of the Positivist and the Interpretivism (or Phenomenology) way. The Positivism perspective is argued as being involved in the application of the ways of the natural sciences; it represents a more scientific methods and focuses on the capable for defining research through more systematic and statistical /approach, leading to highly structured methodologies that generate data which can be effortlessly replicated in subsequent research (Bryman and Bell 2003). Based on the concept which the world is comprised of upon a lot of truths, interpretivism is an Epistemological position. There must be more than one answer to the research question. That is why it is essential to decide the significances and intentions behind individual actions for the purpose of understanding them. Interpretive is argued that strongly associated with qualitative approaches to research because of it focusing on the meaning, while it is compared with the measurement of social phenomena (Collis and Hussey 2003). Based on the research purpose stated in the Introduction, although it is obvious that these cannot be replied from a systemic or scientific approach which is featured of the Positivist standpoint, it can only be replied from an Interpretivism perspective that seeks to comprehend the true of a situation by acquiring a rich insight into the theme area.
3.2 Research Approach In choosing the research approach it is significant to decide the nature of the relation between research and theory, the research approach is dependent on whether the theory is formed as a prolusion to the research process, or an inference of the research process by Saunders et al. (2007). 3.2.1 Deductive or Inductive The deductive way to research design is based on logical reasoning. It assumes an explicit knowledge and comprehension of the theoretical background prior to the data being gathered. Ghauri and Gronhaug (2005), permit the researcher to get conclusions from a premise that is known to be genuine. It is in contrast to the inductive approach in which data is gathered and theory is then formed as conclude of the research. Within this research a overview of the in being theory and literature identified a list of pre decided subjects which composed the responsive SC, which the research approach was subsequently structured around; It is representative of a more deductive approach to the research process (Saunders et al 2003). The researcher thinks that insert the data collection process with an explicit theoretical knowledge which will add dependability to the result. But the researcher was also penetrating not to let pre-decided frameworks prohibit the growth of new insights which is representative of a more Inductive approach to research design. As a result, the researcher was based on a predominantly deductive method, but was also probable to be effected by the inductive perspective. Meanwhile some authors accept the deductive approach as being identified with the philosophy of Positivism. The characteristic of inductive and deductive approaches into detailed exemplifications is misleading and serves no actual value (Saunders et al2003).
3.3 Research Strategy There are a lot of researches strategies which can be adopted, meanwhile some of these strategies pertain to the Positivist and Interpretivism philosophies .Allocating strategies to especial philosophies is excessively simplistic that is argued by Saunders et al (2003). The following identifies plentiful strategies which can be employed that are part of both Positivist and Interpretivism philosophies: . Experiment . Survey . Case Study . Action Research . Exploratory, Descriptive and Explanatory studies In choosing a research strategy it is crucial to select a right strategy that would answer the stated research objectives. The researcher chooses to do a case study analysis.
3.3.1 Qualitative and quantitative Qualitative and quantitative research strategies are two kinds of methods adopted in research. "Qualitative research is a research strategy that usually emphasizes words rather than quantification in the collection and analysis of data" (Bryman and Bell 2003). In this dissertation, qualitative approach will be adopted. Whilst there will be a small part of quantitative data used to response some conditions in the case precisely. "In very broad terms, it was described as entailing the collection of numerical data and as exhibiting a view of the relationship between theory and research as deductive, a predilection for a natural science approach (and of positivism in particular), and as having an objectivist conception of social reality" (Bryman and Bell 2003). There are the contrasts between quantitative and qualitative approaches in table
3.1. |Qualitative |Quantitative | |Words |Numbers | |Points of view of participants |Point of view of researcher | |Research close |Research distant | |Theory emergent |Theory testing | |Process |Static | |Unstructured |Structured | |Contextual understanding |Generalization | |Rich, deep data |Hard, reliable data | |Micro |Macro | |Meaning |Behavior | |Natural settings |Artificial settings | Table
3.1 common contrasts between quantitative and qualitative research Source: Bryman and Bell 2003 Moreover, "...quantitative data analysis is: '...a field where it is not at all difficult to carry out an analysis which is simply wrong for your purposes, and the negative side of readily available analysis software is that it becomes that much easier to generate elegantly presented rubbish ' " (Robson 1993, cited in Saunders et al. 2000). Therefore, in this dissertation a qualitative approach will be adopted. 3.3.2 Case Study Case study is defined as the 'development of detailed, intensive knowledge about a single "case", or a small number of related "cases"' by Robson (1993:40) (Cited Saunders et al. 2000). Morris and Wood (1991) indicated that case study can help to acquire a rich understanding of the context of the research. Besides, with case study, it is easy to analyze comprehensively the complex relationships and various conditions of logistics. In this dissertation, the information of a Chinese sub-project named Hubei Beijing-Zhuhai expressway Da Wu Bei Duan (JZDWBD-V) will be presented and used ant colony algorithm to solve. The results calculated in this dissertation will compare with other heuristic algorithm (Chai, 2005).
3.3.3 Data collection The data, which has already been collected by some other people and is re- analyzed for a new purpose, is secondary data (Saunders et al. 2000). Because the project-JZDWBD-V is used as a case in this dissertation is a very representative of actual project and it has been completed, so enough information about this project can be collected. The data of the project can be got from public plan of the project, reports of JZDWBD-V itself, People's Daily, magazines, newspapers of Chinese government, and so on. Moreover, compared with primary data, secondary data is easier to get with modern media. The process of collecting data will be more time-saving and the data which can be collected should be relatively completed. So in this dissertation, the method of case study will be used to apply the model and achieve the aim. 3.4 Data Information 3.4.1 Area Choice In this dissertation, the project named JZDWBD-V in China is chosen as a case to study, one reason of which is that China is still an area where Net Present Value problem has not developed in to a high level and developed lately while it is experiencing a high speed growing period. With China becoming the centre of production and purchase all over the world, now China gets an uncommon chance for engineering project because of economic globalization and special conditions of China(Fueling 2008). In the period of the rapid economic development, there are some super Chinese project planning projects emerging, for example: JZDWBD-V , although Chinese industry has not reached a mature stage and still has the problem and most of current Chinese network project cannot satisfy the demand of the market because of still be in its primary stage. In this situation, the problems emerging and benefits network project providing to deserve special mention. So China is chosen to study further. 3.4.2 Project Choice This dissertation will be based on a Chinese project called JZDWBD-V. JZDWBD-V is a sub-project of JZDWBD which is the fifth contract period. The study of this project is believed to provide a further understanding of external environment of Chinese project and operations and strategies inside of the project. The total project contract value of JZDWBD-V is 160.077 million Yuan, 5 percent has paid first in the first contract period, and another 5 percent which works as quality warranty is paid if there is no big quality accident happened during the warranty. So the following funds is 90 percent of the JZDWBD-V. 3.5 Research plan and data analysis In order to get enough and believable information for this research, public plan of the project, reports of JZDWBD-V itself, People's Daily, magazines and so on will be searched, compared, classified and adopted. So the amount of information and reliability can be guaranteed. Mainly two aspects of JZDWBD-V project will be focused on: . Make the project construction date is the shortest . Make the project income maximization First and foremost, the background of JZDWBD-V will be introduced. This first step will provide a general understanding of the project, so we can get a general impression of JZDWBD-V. Then, the most important information about JZDWBD-V's network planning it involved will be given: . Resource constraints Construction projects need all kinds of resources in the work progress. According to the different nature of resources, they are divided into: renewable resources, nonrenewable resources and double resource constraints. Renewable resources usually refer to available quantity under restrictions in each period. Common renewable resources are human, equipment, etc. Nonrenewable resources usually refer to available quantity under restrictions in the whole period, for example: raw material, etc. Double resource constraints usually refer to available quantity under restrictions in each period and the whole period, for example: funds, etc. . The practical start time and completion time The practical start time of activities of network planning under resource constraints often becomes the key of optimization. This problem is called schedule mechanisms. Determining the actual start time is the equivalent of determining scheduled plan. . Cash flow analysis How to evaluate a project' interest? It needs to be measured according to the specific evaluation index. It can be divided into static and dynamic evaluation indexes according to consider the time value of money or not. Dynamic evaluation indexes of more intuitive to reflect the profitability of the project. Dynamic evaluation indexes usually include dynamic investment recoupment period, the dynamic investment effect coefficient, net present value and internal rate of return, etc. Among them, net present value is a dynamic evaluation index which is used frequently. . Project rewards and punishment In practice, days for construction in the contract are general longer than in the network planning. So the choice of awards contract increased the possibility of income for construction builder. Using awards contract has the following advantages: 1) Relative to total price contract, there is much less risk of construction builder; 2) Construction builder will choose reasonable activity mode, which can not only shorten the construction period, but obtain the reward to increase profits. 3) Due to the existence of rewards, it makes the construction builder's income have security. Rewards can be gained in the situation which the project can be finished ahead of the schedule by the construction builder and project acceptance.
3.6 Problems and limitation Due to just one project are concentrated on, the value of this dissertation may be limited because it is not able to reflect all relevant areas of Chinese projects. However, the case chosen in this dissertation is very typical, so most of relevant issues will be tried to be covered. The data in this dissertation are secondary data, which cannot be real-time and creditability may be a problem. However, in data collection process, the last data will be pursued. And because all data comes from regular media, so the accuracy and creditability should be appropriate. Just with qualitative and some issues may not be able to be presented very exactly and clearly, so small part of quantitative data will be used. Furthermore, it is possible that the research contains some bias because when using the research method of qualitative, some personal opinions may be combined.
4. Findings 4.0 Introduction In this chapter, Ant colony algorithm is applied in JZDWBD-V to solve the maximum net present value and will be compared with other algorithm to show its benefits. Within the analysis, the theory covered in Chapter 2- Literature Review will be used to help analyze and tell the difference between conditions in china and general issues raised by authors. The questions about specific objectives of this research raised in methodology will be answered. And at the end of this chapter, a summary will be given.
4.1 project data Figure 4.1 is the project network diagram, and each activity is defined two exec mode---normal mode and crashed mode. Table 4.1 shows all activities' currency quantities and data and cost in different exec mode. Other parameters of the project are as follow: the payment time (K)is 4; According to the previous operation data, the owners' expected earnings(B) estimates for 2899 Yuan; The discount rate(?=0.0002) sets as the construction bank loan interest rate; The project will set the start time as 0; the deadline (D) is 22; the proportion (?) of cost sharing of project finance is 0.01; Because of this project cost (especially materials cost ) happen in start time ,so the ? is 0.8. [pic] Figure
4.1 Activity-on-Activity Networks Source: He, 2006 It can be seen that this example uses double codes network diagram. Because this paper use single code network diagram as the research object, so it will be transformed into single code network diagram and shown in figure 4.2. [pic] Figure
4.2 Activity-on-node Network in Reference Source: He, 2006. In the figure, node S represents begins activities, node F represents end activities, node E1 and E2 represent virtual activities separately. These four activities are not time consuming and resources consuming. |Activitie|mode |resources |date |Cumulative| |s Numbers| | | |value | | | |Resource1|Resource|Resource| | | | | | |2 |3 | | | |1 |normal |12 |0 |0 |5 |700 | | |mode | | | | | | | |Crash mode|24 |0 |0 |3 | | |2 |normal |16 |0 |2 |6 |2000 | | |mode | | | | | | | |Crash mode|16 |4 |0 |5 | | |3 |normal |8 |0 |0 |3 |300 | | |mode | | | | | | | |Crash mode|14 |0 |0 |2 | | |4 |normal |6 |2 |0 |4 |600 | | |mode | | | | | | | |Crash mode|6 |0 |2 |3 | | |5 |normal |6 |0 |0 |3 |200 | | |mode | | | | | | | |Crash mode|10 |0 |0 |2 | | |6 |normal |12 |4 |0 |4 |1600 | | |mode | | | | | | | |Crash mode|14 |0 |3 |6 | | |7 |normal |8 |0 |0 |5 |600 | | |mode | | | | | | | |Crash mode|2 |2 |0 |6 | | |8 |normal |6 |0 |0 |6 |400 | | |mode | | | | | | | |Crash mode|4 |0 |1 |4 | | |9 |normal |12 |3 |0 |8 |2000 | | |mode | | | | | | | |Crash mode|12 |0 |3 |6 | | |10 |normal mode|14 |0 |0 |4 |600 | | |Crash mode|4 |4 |0 |3 | | Table 4.1 Activity-on-node Network's Activity Date Source: He, 2006 Table 4.2 lists the main parameters of resources in the example. |Resource' type |Maximum amount |Resource costs | |Resource 1 |28 |10 | |Resource 2 |5 |40 | |Resource 3 |3 |70 | Table
4.2 Resources' Date Source: He,2006. It can be got the cost at normal mode and crash mode separately from the table 4.1 and
4.2. The specific data shows in table
4.3. |Activities |Mode |Cost | |Numbers | | | |1 |normal mode |600 | | |crash mode |720 | |2 |normal mode |1800 | | |crash mode |1600 | |3 |normal mode |240 | | |crash mode |280 | |4 |normal mode |560 | | |crash mode |600 | |5 |normal mode |180 | | |crash mode |200 | |6 |normal mode |1400 | | |crash mode |1400 | |7 |normal mode |480 | | |crash mode |500 | |8 |normal mode |360 | | |crash mode |440 | |9 |normal mode |1920 | | |crash mode |1980 | |10 |normal mode |560 | | |crash mode |600 | Table 4.3 Activity's Cost Source: He, 2006. 4.2 Particle Swarm Optimization Particle Swarm Optimization (PSO) suggested together by American social psychologists James-Kennedy and electrical engineer Russell - Eberhart in 1995. The basic idea was inspired by the results of birds' group activities and uses the model of biological community of the biologist Frank. Since this algorithm was put forward, many scholars paid close attention. At present, this algorithm has become an important branch of optimization algorithm and applies to many areas successfully. 4.2.1 The discrete particle swarm algorithm From the analysis of the preceding chapter, there are three main variables in this algorithm: mode variable, pay variable and activity's sequence variables. The three variables are discrete which mode variable and pay variable is 0-1 variables, activity's sequence variable is integral space variable. The characteristics of these variables determine that it is necessary to apply the discrete particle swarm algorithm to solve the maximum net present value in this dissertation.
4.2.2 Compared with other algorithms . Genetic algorithm Genetic algorithm was proposed in the 1960s. American scholar John H. Holland studied biological genetic method at the earliest. In 1967, his student named J.D.Bagley put forward the concept of genetic algorithm. Genetic algorithm needs to encode problems (generally adopts binary form). The algorithm starts at randomly initial population, produces next generation through some operator (selection, crossover and mutation), then sets the new generation of the species at start and repeats this process until termination conditions is satisfied. At present genetic algorithm has formed a set of mature theoretical system and has applied extensively in many problems. Particle swarm algorithm has much in common with genetic algorithm. For example: both of them are random search algorithm and have global search capability; update according to the individual's adaptation value. Compared with genetic algorithm, the particle swarm optimization algorithm has the following advantages: it has good memory which can remember the best solution; coding technology is relatively simple and practical; Algorithm convergence is unidirectional and search speed is fast. . Ant Algorithm Ant algorithm was born in the early 1990s which raised by Italy scholars Colorni and Dorigod. This algorithm takes example by the ants foraging behavior characteristics whose principle is enhanced positive feedback learning system. There are two important characteristics of the algorithm: positive feedback mechanism and distributed parallel searching ability. Using this feature, the algorithm can quickly find the optimal solution of the problem. The algorithm has been used in salesman problem, the second assignment problem, vehicle scheduling and it shows a fairly good performance. Particle swarm algorithm also has in common with ant algorithm. For example: Randomness, global characteristic. Ant algorithm has its own advantages. Such as: Enhanced and distributed search which improve the performance of the algorithm. But the ant algorithm has some faults. For example: stagnant and search speed is slow. Besides ant algorithm's memory is inferior to particle group algorithm. Next the table
4.4 will show the difference of those algorithms. |The algorithm |Advantage |disadvantage | |Particle group |Good memory |Centralized search | |algorithm |Simple coding | | | |technology | | | |Search speed is fast| | | | | | | |practical | | |Genetic algorithm|Global search |Complex coding technology | | |Mature system info |Algorithm convergence is | | | |bidirectional | |Ant algorithm |Enhanced and |stagnant | | |distributed search |search speed is slow | Table 4.4 The difference of algorithms 4.3 Encoding design of Variable Encoding design is the connection of algorithm and problem which is a process that translates variables abstracted in the problem. Encoding design should combine the characteristics of problem and the characteristics of algorithm. 4.3.1 Decision variable The objective in this dissertation is that study the net present value maximization problem in network project. Activities' executive sequence and start time is connected to each factor. Cash inflows and outflows are closely related to activities' actual start time, which are the major factors to affect the optimizing targets. Resource is one of the important factors to affect activities' actual start time. Under the condition of resource constraints, activities' actual start time is no longer simply decided by the logical relationship of activities, but determined by the resource constraints and logical relationship of activities jointly. Executive mode is one of the important factors in optimal result and is also a factor that should be considered in the evaluation function. Because executive mode is related to activities, executive mode variable is one to one correspondence with activity's sequence. Besides payment is a necessary factor to consider which affects the optimal results, but it is not the key factor to the final project progress plan. This factor is the main influence factors of the net present value. it is also associated with activity and the activity's sequence. Therefore, it will be linked with activity's sequence. The main variables in the algorithm are as follows: Payk: The amount of payment in the k times; Pn: whether the activity n is paid or not; Lnm: executive mode of activity n; RSn, RFn: The actual start time and the actual end time of activity n; RD: another name of RFn; 4.3.2 The complexity of the variables Among three main variables, the first one is integral space variable. Those combinations are related to the number of activities theoretically. There are [pic] kinds of combinations. But since the beginning and end of the project must be arranged at the first and the last 代写留学生论文activity in network chart, the combination number are[pic]. Besides, there are constraints of logical relationship among activities, the number are necessarily less than[pic].The second one is 0-1 variable. Those combinations are related to the number of activities theoretically, there are 2N kinds of combinations. The practical combination is corresponded to theoretical one. The third one is also 0-1 variable. But its theoretical combination is not only affected by the number of activities, but also by the number of executive mode. The combination numbers are MN. The practical combination is corresponded to theoretical one. This clearly proves the complexity of variables is less than [pic]*2N*MN, more than 2N*MN. It belongs to combinatorial optimization problem. The more complexity of the variable is, the higher requirements of optimal performance are needed. ----------------------- Job costs Direct costs Indirect costs Date A
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