Four payment models for the multi-mode resource constrained project scheduling problem with discounted cash flows

In this paper, the multi-mode resource constrained project scheduling problem with discounted cash flows is considered. The objective is the maximization of the net present value of all cash flows. Time value of money is taken into consideration, and cash in- and outflows are associated with activities and/or events. The resources can be of renewable, nonrenewable, and doubly constrained resource types. Four payment models are considered: Lump sum payment at the terminal event, payments at prespecified event nodes, payments at prespecified time points and progress payments. For finding solutions to problems proposed, a genetic algorithm (GA) approach is employed, which uses a special crossover operator that can exploit the multi-component nature of the problem. The models are investigated at the hand of an example problem. Sensitivity analyses are performed over the mark up and the discount rate. A set of 93 problems from literature are solved under the four different payment models and resource type combinations with the GA approach employed resulting in satisfactory computation times. The GA approach is compared with a domain specific heuristic for the lump sum payment case with renewable resources and is shown to outperform it

Scheduling projects with linear time-dependent cash flows to maximize the net present value.

In this paper we study the unconstrained project scheduling problem with discounted cash flows where the net cash flows are assumed to be linear dependent on the completion times of the corresponding activities. Each activity of this unconstrained project scheduling problem has a known deterministic net cash flow which is linear and non-increasing in time. Progress payments and cash outflows occur at the completion of activities. The objective is to schedule the activities in order to maximize the net present value (npv) subject to the precedence constraints and a fixed deadline. Despite the growing amount of research concerning the financial aspects in project scheduling, little research has been done on the problem with time-dependent cash flows. Nevertheless, this problem gives an incentive to solve more realistic versions of project scheduling problems with financial objectives. We introduce an extension of an exact recursive algorithm which has been used in solving the max-npv problem with time-independent cash flows and which is embedded in an enumeration procedure. The recursive search algorithm schedules the activities as soon as possible and searches for sets of activities to shift towards the deadline in order to increase the net present value. The enumeration procedure enumerates all sets of activities for which such a shift has not been made but could, eventually, have been advantageous. The procedure has been coded in Visual C++ version 4.0 under Windows NT and has been validated on a randomly generated problem set.Net present value; Scheduling; Cash flow; Discounted cash flow; Studies; Problems;

An equitable approach to the payment scheduling problem in project management

This study reports on a new approach to the payment scheduling problem. In this approach, the amount and timing of the payments made by the client and received by the contractor are determined so as to achieve an equitable solution. An equitable solution is defined as one where both the contractor and the client deviate from their respective ideal solutions by an equal percentage. The ideal solutions for the contractor and the client result from having a lump sum payment at the start and end of the project respectively. A double loop genetic algorithm is proposed to solve for an equitable solution. The outer loop represents the client and the inner loop the contractor. The inner loop corresponds to a multi-mode resource constrained project scheduling problem with the objective of maximizing the contractor's net present value for a given payment distribution. When searching for an equitable solution, information flows between the outer and inner loops regarding the payment distribution over the event nodes and the timing of these payments. An example problem is solved and analyzed. A set of 93 problems from the literature are solved and some computational results are reported

Client-contractor bargaining on net present value in project scheduling with limited resources

The client-contractor bargaining problem addressed here is in the context of a multi-mode resource constrained project scheduling problem with discounted cash flows, which is formulated as a progress payments model. In this model, the contractor receives payments from the client at predetermined regular time intervals. The last payment is paid at the first predetermined payment point right after project completion. The second payment model considered in this paper is the one with payments at activity completions. The project is represented on an Activity-on-Node (AON) project network. Activity durations are assumed to be deterministic. The project duration is bounded from above by a deadline imposed by the client, which constitutes a hard constraint. The bargaining objective is to maximize the bargaining objective function comprised of the objectives of both the client and the contractor. The bargaining objective function is expected to reflect the two-party nature of the problem environment and seeks a compromise between the client and the contractor. The bargaining power concept is introduced into the problem by the bargaining power weights used in the bargaining objective function. Simulated annealing algorithm and genetic algorithm approaches are proposed as solution procedures. The proposed solution methods are tested with respect to solution quality and solution times. Sensitivity analyses are conducted among different parameters used in the model, namely the profit margin, the discount rate, and the bargaining power weights

Client-contractor bargaining on net present value in project scheduling with limited resources

The client-contractor bargaining problem addressed here is in the context of a multi-mode resource constrained project scheduling problem with discounted cash flows, which is formulated as a progress payments model. In this model, the contractor receives payments from the client at predetermined regular time intervals. The last payment is paid at the first predetermined payment point right after project completion. The second payment model considered in this paper is the one with payments at activity completions. The project is represented on an Activity-on-Node (AON) project network. Activity durations are assumed to be deterministic. The project duration is bounded from above by a deadline imposed by the client, which constitutes a hard constraint. The bargaining objective is to maximize the bargaining objective function comprised of the objectives of both the client and the contractor. The bargaining objective function is expected to reflect the two-party nature of the problem environment and seeks a compromise between the client and the contractor. The bargaining power concept is introduced into the problem by the bargaining power weights used in the bargaining objective function. Simulated annealing algorithm and genetic algorithm approaches are proposed as solution procedures. The proposed solution methods are tested with respect to solution quality and solution times. Sensitivity analyses are conducted among different parameters used in the model, namely the profit margin, the discount rate, and the bargaining power weights

Ultrasound tiga - dimensi

Latarbelakang : Laporan projek ini dibuat bagi menilai kemampuan aplikasi ultrasonografi tiga dimensi (3-D) di dalam pemaparan visual fetus pada trimester ketiga di Hospital Universiti Sains Malaysia Kubang Kerian. Percubaan awal telah dilakukan secara in-vitro ke atas fantom ultrasaun setaraan tisu, bagi mendapatkan imej-imej satahan yang berserenjang, imej arbitrari dan pembinaan semula imej berpeleraian tinggi serta imej render isipadu secara interaktif. Peleraian mesin-mesin ultrasaun juga dibincangkan. Kaedah : Imej-imej in-vitro dan in-vivo 3-D dijana menerusi penggunaan sistem pengimejan ultrasaun yang berlainan, dengan masingmasing berada di Jabatan Radiologi dan Jabatan Obstetrik dan Ginekologi. Sistemsistem tersebut ialah : Sistem Pengimejan Ultrasaun Sonoline Siemens Elegra yang dilengkapi dengan transduser tatasusunan linear dan sektor pada pelbagai julat frekuensi dan Sistem Pengimejan Ultrasaun ATL HDI Phillips. Pemerolehan imej dilakukan melalui kaedah pengimbasan linear dan ayunan. Keputusan : Melalui dua sistem pengimejan yang digunakan, struktur-struktur dua dimensi (2-D) dan 3-D fetus dan fantom daripada pelbagai perspektif dan orientasi dapat dilihat menerusi paparan empat sukuan secara serentak. Tentukuran ketepatan kaliper dan peleraian di antara kedua-dua sistem memberikan keputusan yang pelbagai bergantung kepada jenis transduser dan frekuensi yang digunakan. Kesimpulan : Ultra sonografi secara 3-D memberikan satu dimensi baru di dalam pemaparan visual struktur-struktur anatomi. Hasil yang diperoleh menunjukkan ultrasonografi 3-D bermaya menjadi pelengkap kepada ultrasonografi 2-D dan ianya sangat berguna di dalam menilai keadaan fetus dalam kandungan kehamilan. Penggunaan peralatan pengimbasan mekanikal bermotor dan alat pengesan kedudukan pengimbas tangan bebas juga telah dicadangkan

Project network models with discounted cash flows. A guided tour through recent developments.

The vast majority of the project scheduling methodologies presented in the literature have been developed with the objective of minimizing the project duration subject to precedence and other constraints. In doing so, the financial aspects of project management are largely ignored. Recent efforts have taken into account discounted cash flow and have focused on the maximalization of the net present value (npv) of the project as the more appropriate objective. In this paper we offer a guided tour through the important recent developments in the expanding field of research on deterministic and stochastic project network models with discounted cash flows. Subsequent to a close examination of the rationale behind the npv objective, we offer a taxonomy of the problems studied in the literature and critically review the major contributions. Proper attention is given to npv maximization models for the unconstrained scheduling problem with known cash flows, optimal and suboptimal scheduling procedures with various types of resource constraints, and the problem of determining both the timing and amount of payments.Scheduling; Models; Model; Discounted cash flow; Cash flow; Project scheduling; Project management; Management; Net present value; Value; Problems; Maximization; Optimal;

An ultrasonic system for profiling bubblers in water

Multi-phase flow occurs as two or more discrete phases flow in a closed pipe or a vessel. Examples of phases include gas, liquid or solid and also different immiscible liquids or solids[1]. Two phase flow of fluids (e.g. gas/liquid, liquid/liquid, etc.) is an important phenomenon in which two immiscible phases coexist in a thermodynamic equilibrium. As a two phase flow regime, bubbly flow column are intensively used as multiphase contactors and reactors in chemical, biochemical and petrochemical industries. Investigation of design parameters characterizing the operation and transport phenomena of bubble columns have led to better understanding of the hydrodynamic properties, heat and mass transfer mechanisms and flow regime characteristics ongoing during the operation[2, 3]. Due to the stringent regulations on precise flow control especially in the case of two phase fluid flow,, there has always been a necessity for developing an easier to use, yet more precise approaches or instrumentation. Accordingly, tomographic measurement is more significant and attractable especially in today's industrial process .

Welcome to OR&S! Where students, academics and professionals come together

In this manuscript, an overview is given of the activities done at the Operations Research and Scheduling (OR&S) research group of the faculty of Economics and Business Administration of Ghent University. Unlike the book published by [1] that gives a summary of all academic and professional activities done in the field of Project Management in collaboration with the OR&S group, the focus of the current manuscript lies on academic publications and the integration of these published results in teaching activities. An overview is given of the publications from the very beginning till today, and some of the topics that have led to publications are discussed in somewhat more detail. Moreover, it is shown how the research results have been used in the classroom to actively involve students in our research activities

A survey of variants and extensions of the resource-constrained project scheduling problem

The resource-constrained project scheduling problem (RCPSP) consists of activities that must be scheduled subject to precedence and resource constraints such that the makespan is minimized. It has become a well-known standard problem in the context of project scheduling which has attracted numerous researchers who developed both exact and heuristic scheduling procedures. However, it is a rather basic model with assumptions that are too restrictive for many practical applications. Consequently, various extensions of the basic RCPSP have been developed. This paper gives an overview over these extensions. The extensions are classified according to the structure of the RCPSP. We summarize generalizations of the activity concept, of the precedence relations and of the resource constraints. Alternative objectives and approaches for scheduling multiple projects are discussed as well. In addition to popular variants and extensions such as multiple modes, minimal and maximal time lags, and net present value-based objectives, the paper also provides a survey of many less known concepts. --project scheduling,modeling,resource constraints,temporal constraints,networks