Razman Mat Tahar

Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

Using system dynamics to evaluate renewable electricity development in Malaysia

Purpose – The purpose of this paper is to provide an assessment of Malaysias renewable capacity target. Malaysia relies heavily on fossil fuels for electricity generation. To diversify the fuel-mix, a technology-specific target has been set by the government in 2010. Considering the complexity in generation expansion, there is a dire need for an assessment model that can evaluate policy in a feedback fashion. The study also aims to expand policy evaluation literature in electricity domain by taking a dynamic systems approach. Design/methodology/approach – System dynamics modelling and simulation approach is used in this study. The model variables, selected from literature, are constituted into casual loop diagram. Later, a stock and flow diagram is developed by integrating planning, construction, operation, and decision making sub-models. The dynamic interactions between the sub-sectors are analysed based on the short-, medium- and long-term policy targets. Findings – Annual capacity constructions fail t...

Understanding the complexity of container terminal operation through the development of system dynamics model

The competitiveness among container terminals is growing due to the positive growth of containerised shipping. The ability to provide efficient services very much depend on the overall efficiency of the container terminal. However, the operation of the container terminal is complex and consists of many subsystems such as the berth and yard. Moreover, the planning and decision making of the berth and yard are usually conducted separately, not as a whole. Therefore, with the lack of integration between these two major subsystems, terminal managers fail to see the impact of the decision made at the berth to the yard and vice versa. This paper presents the application of system dynamics simulation into capturing the operation processes of the berth and yard. The system dynamics model is able to enhance the understanding on the interdependency and relationship between these two subsystems, thus assisting the terminal managers in decision making.

Heat and Mass Transfer in a Micropolar Fluid with Newtonian Heating: An Exact Analysis

Heat and mass transfer phenomenon in a micropolar fluid is analyzed. The fluid occupies the space over an infinite oscillating vertical plate with Newtonian heating. The plate executes cosine type of oscillations. Exact solutions are obtained using the Laplace transform technique. Expressions for velocity, microrotation, temperature and concentration are obtained. Graphs for velocity and microrotation are plotted for various embedded parameters and discussed.

Enhancing efficiency of automobile assembly line using the Fuzzy logical and Multi-objective Genetic Algorithm

Automobile manufacturing is one of the most important industries in the world. Assembly line is one of the main supply chain of the industry. It contains several workshops and stations where each station consists of many different tasks. These tasks are processed by workers using tools and machines. The unbalancing time is the main problem of the assembly line. This issue presented by the Cycle Time station (CTs) which is unequal among stations that resulted in queuing and idle time which inhabit the productivity of the assembly line. In this study, Multi-Objectives Model (MOM) and Genetic Algorithm System (GAs) are combined to form (MOGA) in order to solve the assembly line issues. The Fuzzy Logical Control (FLC) organizes an application of the MOGA to solve the Assembly Line Unbalancing (ALB). The new technique in this study is use to develop the efficiency of the assembly line and to solve the unbalancing problem among stations. The developed MOGA will increase the volume of the production and reduce the queuing and the idle time and maximizing the productions by increase the efficiency of working time. In addition, the models will be redistributed the responsibilities to the workers to minimize the queuing and idle time among the stations and append new workers to obtain the optimum balance. The modern approach will obtain an optimum balance and enhances the efficiency of the assembly line.

Numerical solution of the free convection boundary layer flow over a horizontal circular cylinder with convective boundary conditions

Numerical solution for the steady free convection boundary layer flow near the lower stagnation point of a horizontal circular cylinder subjected to a convective boundary condition, where the heat is supplied to the fluid through a bounding surface with a finite heat capacity are presented in this paper. The governing boundary layer equations are transformed using non-similar variables into non-similar equations and were solved numerically using an implicit finite difference scheme known as the Keller-box method. The solutions are obtained for the skin friction coefficient, the local wall temperature, as well as the velocity and temperature profiles with two the variations of two parameters, namely the conjugate parameter γ and the Prandtl number Pr.

Feedback-Rich Model for Assessing Feed-In Tariff Policy

Abstract The depletion of fossil fuels, environmental concerns, and security of supply risk has put an emphasis on renewable sources of electricity generation. However, the high cost of technology has compelled countries to develop support policies. Feed-in tariff (FIT), which has been successful in many countries, is one such policy. In this study, a qualitative model is presented. This model takes a holistic perspective in developing renewable power infrastructure. To do this, this model takes into account social, environmental, learning effect, and the FIT policy in scaling up the renewable energy capacity. The shortcomings of the FIT policy are highlighted along with improvements in policy structure. Developed from policy makers’ perspective, this model also incorporates investors’ perception of renewable market, in a Malaysian context. Modified structure suggests making the reduction in the FIT price a variable. An additional source of income—by introducing carbon tax on fossil fuel-based generation—is suggested. Furthermore, the government’s policy target has to be made variable subject to support funds availability. The developed model’s aim is to determine whether or not the goal of transforming electricity supply chain using FIT is achievable. This model also aims to show that the qualitative model would serve as a tool for future dialogue and policy improvements.

A framework for emergency department capacity planning using system dynamics approach and the theory of constraints philosophies

Patient waiting time and service delivery problems characterize health care services and are more acute in an emergency department (ED).With more patients needing care and fewer resources to care for them, ED that operates at or above capacity is inevitable. This paper is a review of work-in-progress of a study being conducted in a government hospital in Penang, Malaysia.This paper proposes a hybrid of System Dynamics (SD) approach and the Theory of Constraints (TOC) in solving health capacity planning. The potential combination of these methods will be reviewed that is hoped to reveal the synergy between the established methods in addressing the health capacity planning options for the long-term future.

Simulating the Effect of Feed-In Tariff on Renewable Energy Penetration: A System Dynamics Approach

In Malaysia, solar photovoltaic (PV) has got the most beneficial feed-in tariff (FIT) rates as compared to other technologies. Managing continued investments and payments is a complex task for the government due to uncertainty, nonlinearity, and dynamics involved. The objective is to develop an assessment model which can evaluate the FIT scheme for solar PV system. The model is based upon system dynamics methodology to develop a simulation for assessing FIT policy. 2012–2050 is the time horizon used in simulations. We modelled the interconnection of FIT and other important variables in a feedback fashion. The interconnection in the system is between FIT rate, cumulative PV capacity, cumulative carbon emission avoided, and the amount of funds needed to support the scheme. The technological-economic interactions were modelled by the cost of PV system. Three scenarios corresponding to the highest (S1), average (S2), and a minimum (S3) FIT rates are analysed. A degression rate of 8 % annually in FIT is employed. In S1, with the highest FIT rate of 1.23 RM/kWh, 1148 MW capacity comes on line with expenditure of 5 billion RM. With an average FIT rate of 862 MW, 3.5 billion RM will be paid. Finally, in S3, with the least FIT rate of 0.85 RM/kWh, capacity will be 526 MW and total payment will be 1.7 billion RM for a 21-year period. CO2 emissions cost 0.036 RM/kg, 0.032 RM/kg, and 0.026 RM/kg for S1, S2, and S3, respectively, in 2050.

Managing resource capacity using hybrid simulation

Due to the diversity of patient flows and interdependency of the emergency department (ED) with other units in hospital, the use of analytical models seems not practical for ED modeling. One effective approach to study the dynamic complexity of ED problems is by developing a computer simulation model that could be used to understand the structure and behavior of the system. Attempts to build a holistic model using DES only will be too complex while if only using SD will lack the detailed characteristics of the system. This paper discusses the combination of DES and SD in order to get a better representation of the actual system than using either modeling paradigm solely. The model is developed using AnyLogic software that will enable us to study patient flows and the complex interactions among hospital resources for ED operations. Results from the model show that patients’ length of stay is influenced by laboratories turnaround time, bed occupancy rate and ward admission rate.