Abstract: This article proposes an Ant Colony Optimization
(ACO) metaheuristic to minimize total makespan for scheduling a set
of jobs and assign workers for uniformly related parallel machines.
An algorithm based on ACO has been developed and coded on a
computer program MatlabĀ®, to solve this problem. The paper
explains various steps to apply Ant Colony approach to the problem
of minimizing makespan for the worker assignment & jobs
scheduling problem in a parallel machine model and is aimed at
evaluating the strength of ACO as compared to other conventional
approaches. One data set containing 100 problems (12 Jobs, 03
machines and 10 workers) which is available on internet, has been
taken and solved through this ACO algorithm. The results of our
ACO based algorithm has shown drastically improved results,
especially, in terms of negligible computational effort of CPU, to
reach the optimal solution. In our case, the time taken to solve all 100
problems is even lesser than the average time taken to solve one
problem in the data set by other conventional approaches like GA
algorithm and SPT-A/LMC heuristics.
Abstract: State-dependent Riccati equation based controllers are
becoming increasingly popular because of having attractive
properties like optimality, stability and robustness. This paper focuses
on the design of a roll autopilot for a fin stabilized and canard
controlled 122mm artillery rocket using state-dependent Riccati
equation technique. Initial spin is imparted to rocket during launch
and it quickly decays due to straight tail fins. After the spin phase, the
roll orientation of rocket is brought to zero with the canard deflection
commands generated by the roll autopilot. Roll autopilot has been
developed by considering uncoupled roll, pitch and yaw channels.
The canard actuator is modeled as a second-order nonlinear system.
Elements of the state weighing matrix for Riccati equation have been
chosen to be state dependent to exploit the design flexibility offered
by the Riccati equation technique. Simulation results under varying
conditions of flight demonstrate the wide operating range of the
proposed autopilot.
Abstract: There are various approaches to implement quality
improvements. Organizations aim for a management standard which
is capable of providing customers with quality assurance on their
product/service via continuous process improvement. Carefully
planned steps are necessary to ensure the right quality improvement
methodology (QIM) and business operations are consistent, reliable
and truly meet the customers' needs. This paper traces the evolution
of QIM in Malaysia-s Information Technology (IT) industry in the
past, current and future; and highlights some of the thought of
researchers who contributed to the science and practice of quality,
and identifies leading methodologies in use today. Some of the
misconceptions and mistakes leading to quality system failures will
also be examined and discussed. This paper aims to provide a general
overview of different types of QIMs available for IT businesses in
maximizing business advantages, enhancing product quality,
improving process routines and increasing performance earnings.
Abstract: The purpose of the present study is to analyze the
effect of the target plate-s curvature on the heat transfer in laminar
confined impinging jet flows. Numerical results from two
dimensional compressible finite volume solver are compared
between three different shapes of impinging plates: Flat, Concave
and Convex plates. The remarkable result of this study proves that
the stagnation Nusselt number in laminar range of Reynolds number
based on the slot width is maximum in convex surface and is
minimum in concave plate. These results refuse the previous data in
literature stating the amount of the stagnation Nusselt number is
greater in concave surface related to flat plate configuration.
Abstract: In this work, we incorporated a quartic bond potential
into a coarse-grained bead-spring model to study lubricant adsorption
on a solid surface as well as depletion instability. The surface tension
density and the number density profiles were examined to verify the
solid-liquid and liquid-vapor interfaces during heat treatment. It was
found that both the liquid-vapor interfacial thickness and the
solid-vapor separation increase with the temperatureT* when T*is
below the phase transition temperature Tc
*. At high temperatures
(T*>Tc
*), the solid-vapor separation decreases gradually as the
temperature increases. In addition, we evaluated the lubricant weight
and bond loss profiles at different temperatures. It was observed that
the lubricant desorption is favored over decomposition and is the main
cause of the lubricant failure at the head disk interface in our
simulations.
Abstract: Impinging jets are used in various industrial areas as a cooling and drying technique. The current research is concerned with the means of improving the heat transfer for configurations with a minimum distance of the nozzle to the impingement surface. The impingement heat transfer is described using numerical methods over a wide range of parameters for an array of planar jets. These parameters include varying jet flow speed, width of nozzle, distance of nozzle, angle of the jet flow, velocity and geometry of the impingement surface. Normal pressure and shear stress are computed as additional parameters. Using dimensionless characteristic numbers the parameters and the results are correlated to gain generalized equations. The results demonstrate the effect of the investigated parameters on the flow.
Abstract: In this experiment, we investigated the performance of
two types of heat sink, swaged- and extruded-type, used in the inverter
of industrial electricity generator. The swaged-type heat sink has 62
fins, and the extruded-type has 38 fins having the same dimension as
that of the swaged-type. But the extruded-type heat sink maintains the
same heat transfer area by the laterally waved surface which has 1 mm
in radius. As a result, the swaged- and extruded-type heat sinks
released 71% and 64% of the heat incoming to the heat sink,
respectively. The other incoming heat were naturally convected and
radiated to the ambient. In spite of 40% decrease in number of fins, the
heat release performance of the extruded-type heat sink was lowered
only 7% than that of the swaged-type. We believe that, this shows the
increment of effective heat transfer area by the laterally waved surface
of fins and the better heat transfer property of the extruded-type heat
sink.
Abstract: Air conditioning is mainly use as human comfort
cooling medium. It use more in high temperatures are country such as
Malaysia. Proper estimation of cooling load will archive ideal
temperature. Without proper estimation can lead to over estimation or
under estimation. The ideal temperature should be comfort enough.
This study is to develop a program to calculate an ideal cooling load
demand, which is match with heat gain. Through this study, it is easy
to calculate cooling load estimation. Objective of this study are to
develop user-friendly and easy excess cooling load program. This is
to insure the cooling load can be estimate by any of the individual
rather than them using rule-of-thumb. Developed software is carryout
by using Matlab-GUI. These developments are only valid for
common building in Malaysia only. An office building was select as
case study to verify the applicable and accuracy of develop software.
In conclusion, the main objective has successfully where developed
software is user friendly and easily to estimate cooling load demand.
Abstract: This paper presents a comparative study of statistical methods for the multi-response surface optimization of a cryogenic freezing process. Taguchi design and analysis and steepest ascent methods based on the desirability function were conducted to ascertain the influential factors of a cryogenic freezing process and their optimal levels. The more preferable levels of the set point, exhaust fan speed, retention time and flow direction are set at -90oC, 20 Hz, 18 minutes and Counter Current, respectively. The overall desirability level is 0.7044.
Abstract: This paper proposed a stiffness analysis method for a
3-PRS mechanism for welding thick aluminum plate using FSW
technology. In the molding process, elastic deformation of lead-screws
and links are taken into account. This method is based on the virtual
work principle. Through a survey of the commonly used stiffness
performance indices, the minimum and maximum eigenvalues of the
stiffness matrix are used to evaluate the stiffness of the 3-PRS
mechanism. Furthermore, A FEA model has been constructed to verify
the method. Finally, we redefined the workspace using the stiffness
analysis method.