H. A. Majid

The Investigation of PIN diode switch on reconfigurable antenna

The investigation and simulation of PIN diode as a switch on reconfigurable antenna are described in this paper. The simulation of the PIN diode model is constructed on CST Simulation tools with the integration of single patch antenna. The radial stub biasing circuit is used for fabrication with the antenna. Three different locations of PIN diode with radial stubs biasing circuit are investigated and analyzed. The result shows the separation of biasing circuit and antenna give a better performance in term of return loss and current distribution.

Circularly polarized textile antenna with bending analysis

A slotted circular polarization (CP) textile antenna is designed for radio frequency (RF) energy harvesting system. The antenna composed a circular patch with cross slot at the centre of the patch. a good bandwidth (2.22 GHz-2.59 GHz), axial ratio (2.38 GHz-2.45 GHz) with directivity gain of 7.34 dBi is presented. This paper also presents the performance of the antenna in bending condition to suits with application of rectenna for energy harvesting system and antenna for monitoring system.

A Framework in Determining Extended Warranty by Using Two Dimensional Delay Time Model

A framework for determining optimal period and cost in extended warranty is proposed in this paper. The optimal period and cost is derived from two-dimensional delay time model. Two-dimensional delay time model is governed by age and mileage. Age and mileage gives effect for the rate of defect arrival λ. The steps for obtaining the model to estimate the optimal period cost of extended warranty is presented. It starts from modeling the defect arrival rate, the impact of preventive maintenance toward the defect arrival rate; determine the delay time distribution, data analyzing and the last optimal cost and period estimation for extended warranty.

Recommended factors for triage categories using Simulation Modelling

Malaysia is in advancement towards the establishment of effective and efficient energy mix plan within its Nuclear Power Programme (NPP) resulting from current governance acceptance and support. Prior precautions have been inculcated in order to comprehend nuclear energy accountability in striving high income economic growth and energy security. This paper is attempting to prescribe nuclear safety recommendations encompassing radiation and nuclear (RN) event recovery phase within integrated disaster operations management (DOM) activities from Soft System Methodology (SSM) perspective by using Simulation Modelling. Possibly, this method is introduced in order to recommend triage categories for vulnerable population groups which are commonly at-risks during RN emergencies, incidents and disasters. Therefore, this paper will proposed some factors of triage categories which may affect these groups whereby representing an initial system map. It is concluded that prioritized suggestions given could possibly ascertain the characteristics of other interventions involved in order to achieve a sustainable and secure nuclear safety in the future.

Reconfigurable band notch UWB antenna using EBG structure

A reconfigurable band notch UWB antenna using EBG structure is proposed. Two EBG structures is positioned alongside the feed line of the UWB antenna. The EBG structures produce two band notched at 3.97 GHz and 5.51 GHz which covers C-band satellite communication system and WLAN. The proposed antenna is suitable for UWB systems that require reconfigurable band reject function.

Design and analysis of metamaterial antenna using Triangular resonator

In this paper, a metamaterial antenna consisting of Triangular resonator (TR) and a thin wire (TW) is proposed. The antenna is excited through a single unit cell left Handed Materials (LHM) which act as the main radiating element via coplanar waveguide (CPW) transmission line. The Left Handedness of the unit cell is investigated and verified. The simulated return loss shows that a bandwidth of 58% is achieved over a frequency band of 6.42-11.23 GHz at a return loss of -10dB. The maximum gain of 4.45 is obtained at a frequency of 10.32GHz. Simulated and measured return loss shows an agreement while the radiation pattern is Omnidirectional.

Miniature dual-fed circularly polarized antenna with slotted ground plane

A new configuration of a dual-fed square patch circular polarization (CP) antenna for WiMAX and energy harvesting application is proposed. The normal dual-fed CP is designed at operating frequency of 2.8 GHz and after introducing a slotted ground plane underneath the radiating patch, the operating frequency is reduced to 2.5 GHz while maintaining the patch size and polarization performance. It was found that, good return loss from 2.5 GHz-2.6 GHz (3.2 %) and axial ratio (AR) bandwidth of 1.22 % with gain of 3.02 dB are achieved by using this technique. Simulated and measured results are used to demonstrate the performance of the antenna.

Microstrip antenna array's gain enhancement via Electromagnetic Band Gap structures

For a point-to-point communication system, an antenna array with high gain is essential and in this work, by incorporating electromagnetic band gap (EBG) structures at a specific location within the antennas peripherals, the gain of the antenna could be enhanced further. The EBG structures reduced mutual couplings between the adjacent patches thus make them radiates effectively. On the other hand, the EBG structures located at the edge of the antenna suppressed surface waves and prevent it from propagating to the edges, thus reduced the side and back lobes. This further enhances the front radiation characteristics of the antenna and also increased the gain. The techniques and guidelines on how to achieve the objectives is presented and the simulated and measured results complement each other.

An improved hybrid of particle swarm optimization and the gravitational search algorithm to produce a kinetic parameter estimation of aspartate biochemical pathways

Mathematical modelling is fundamental to understand the dynamic behavior and regulation of the biochemical metabolisms and pathways that are found in biological systems. Pathways are used to describe complex processes that involve many parameters. It is important to have an accurate and complete set of parameters that describe the characteristics of a given model. However, measuring these parameters is typically difficult and even impossible in some cases. Furthermore, the experimental data are often incomplete and also suffer from experimental noise. These shortcomings make it challenging to identify the best-fit parameters that can represent the actual biological processes involved in biological systems. Computational approaches are required to estimate these parameters. The estimation is converted into multimodal optimization problems that require a global optimization algorithm that can avoid local solutions. These local solutions can lead to a bad fit when calibrating with a model. Although the model itself can potentially match a set of experimental data, a high-performance estimation algorithm is required to improve the quality of the solutions. This paper describes an improved hybrid of particle swarm optimization and the gravitational search algorithm (IPSOGSA) to improve the efficiency of a global optimum (the best set of kinetic parameter values) search. The findings suggest that the proposed algorithm is capable of narrowing down the search space by exploiting the feasible solution areas. Hence, the proposed algorithm is able to achieve a near-optimal set of parameters at a fast convergence speed. The proposed algorithm was tested and evaluated based on two aspartate pathways that were obtained from the BioModels Database. The results show that the proposed algorithm outperformed other standard optimization algorithms in terms of accuracy and near-optimal kinetic parameter estimation. Nevertheless, the proposed algorithm is only expected to work well in small scale systems. In addition, the results of this study can be used to estimate kinetic parameter values in the stage of model selection for different experimental conditions.

Ultra-wideband antenna with tunable Artificial Magnetic Conductor

This paper presents a tunable Artificial Magnetic Conductor (AMC) unit cell design by means of four copper strips. With the inclusion of copper strips, the initial reflection phase of dual band AMC changes from 2.45 GHz and 5.8 GHz to single frequency of 3 GHz. To facilitate the tunable function on antenna performance, an Ultra-Wideband (UWB) antenna has been designed and analyzed. Performance comparison is carried out with and without incorporation of AMC. The AMC is tuned to change frequency using copper strips. Result in terms of reflection phase, return loss and radiation pattern are discussed.