Latifah Mohamed

The Use of a Human Body Model to Determine the Variation of Path Losses in the Human Body Channel in Wireless Capsule Endoscopy

Presently, wireless capsule endoscopy (WCE) is the sole technology for inspecting the human gastrointestinal (GI) tract for diseases painlessly and in a non-invasive way. For the further development of WCE, the main concern is the development of a high- speed telemetry system that is capable of transmitting high-resolution images at a higher frame rate, which is also a concern in the use of conventional endoscopy. A vital task for such a high-speed telemetry system is to be able to determine the path loss and how it varies in a radio channel in order to calculate the proper link budget. The hostile nature of the human bodys channel and the complex anatomical structure of the GI tract cause remarkable variations in path loss at difierent frequencies of the system as well as at capsule locations that have high impacts on the calculation of the link budget. This paper presents the path loss and its variation in terms of system frequency and location of the capsule. Along with the guideline about the optimum system frequency for WCE, we present the difierence between the maximum and minimum path loss at difierent anatomical regions, which is the most important information in the link-margin setup for highly e-cient telemetry systems in next-generation capsules. In order

Complementary structure of quadruple P-spiral split ring resonator (QPS-SRR) on modified Minkowski patch antenna design

In this work, a modified Minkowski patch antenna had been designed for 2.4 GHz of resonant frequency, fr for wireless local area network (WLAN) application. The proposed complimentary structure of quadruple P-spiral split ring resonator (QPS-SRR) into the patch antenna had been increasing the gain performance. Other parameters that had been considered in this work are return loss, bandwidth, radiation pattern and directivity. This paper also discussed on the effect of single, double and triple sets of quadruple P-shape of the Minkowski patch antenna. This Minkowski patch antenna potentially can be operating the frequency range between 2.362 GHz to 2.427 GHz with a resonant frequency at 2.394 GHz and bandwidth of 65 MHz. The return loss of this Minkowski patch antenna is - 26.072 dB at frequency of 2.4 GHz while the gain is 2.555 dB at frequency of 2.4 GHz.

Modified cuckoo search algorithm in weighted sum optimization for linear antenna array synthesis

In this study, we proposed a bio-inspired technique known as modified cuckoo search (MCS)-based weighted sum algorithm towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL) and/or nulls control. The newly evolved metaheuristic algorithm was primarily based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Lévy flight behavior of some birds and fruit flies. Through the integration with the Roulette wheel selection operator and the inertia weight controlling the position (solution) exploration, the MCS-based weighted sum approach optimized concurrently the array element excitation locations, amplitudes, and phases within the uniform pattern and Dolph-Chebyshev window, respectively. The optimal solutions obtained were then compared against the conventional (with λ/2 inter-element distance) and other chosen evolutionary algorithms-based arrays.

Effect of different substrate materials on a wearable textile monopole antenna

In this paper the investigation of the effect using different substrate materials on a textile monopole antenna is discussed. This textile monopole antenna is designed to be used for Body-Centric Wireless Communications (BCWC) at 2.45 GHz. Three types of non-conductive materials were selected: felt, fleece and foam. The textile monopole was benchmarked against a conventional FR-4 monopole antenna. The results demonstrated a good agreement between simulated return loss of all three substrates used for textile monopole antenna and conventional monopole antenna. The felt-based textile monopole antenna offered higher return loss compared to other substrates and conventional monopole antenna. Moreover, the substrate materials gained bandwidths of up to 1000 MHz in free space where fleece fabric produced broader bandwidth compared to other substrates. The simulated gain characteristics for all three types of substrates agreed reasonably well with conventional monopole antenna.

Investigation of sugar cane bagasse as alternative material for pyramidal microwave absorber design

Sugar cane bagasse as is potential agricultural waste to produce an alternative and beneficial product for any suitable application such as pyramidal microwave absorber for anechoic chamber testing application. In this work, the dielectric properties (dielectric constant and tangent loss) of the sugar cane baggase had been measured using the dielectric probe measurement. The sugar can bagasse pyramidal microwave absorber had been modelled and simulate in the CST Microwave Studio using the data from the dielectric probe measurement. This pyramidal microwave absorber had been operating in the microwave frequency range between 0.1 GHz to 20.0 GHz. The targeting reflection loss of this pyramidal microwave absorber is better than - 30 dB. The reflection loss performance comparison with the rice husk also had been done in this work.

Hybrid multiobjective optimization using modified cuckoo search algorithm in linear array synthesis

In this study, we postulated the hybridization of modified cuckoo search (MCS) with two evolutionary algorithms (EAs), which were particle swarm optimization (PSO) and genetic algorithms (GA) in weighted-sum multiobjective optimization towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL) and/or nulls mitigation. The newly nature-inspired MCS algorithm was principally based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Lévy flight behavior of some birds. Through the integration with the Roulette wheel selection operator and the inertia weight controlling the exploration of host nest position (solution), the proposed hybrid MCS-based approach optimized simultaneously three element excitation components including locations, amplitudes, and phases, respectively. The optimal solutions obtained were then analyzed for relative performance comparisons against the conventional, original CS, individual MCS, and hybrid GAPSO-based linear arrays.

Potential of dried banana leaves for pyramidal microwave absorber design

Abandoned agricultural waste pose a risk to the environmental and public health. The polyurethane and polystyrene material for designing pyramidal microwave absorber are expensive and not environmental friendly. Tropical crop residue has potential to be used in the electromagnetic testing area. Nowadays, electromagnetic absorbing materials have been increasingly important in ensuring successful Radio Frequency (RF) anechoic chamber testing performance. New material had been research to reduce the cost of designing pyramidal microwave absorber. In this case, dried banana leaves are mixed with polyester and methyl ethyl ketone peroxide (MEKP) to give the best reflection loss performance to the pyramidal microwave absorber compare to the previous research using rice husk. This pyramidal microwave absorber is operating in the frequency range from 0.1 GHz to 20.0 GHz.

Frequency selective surface for enhance WLAN applications

This paper proposes the deployment of frequency selective surface (FSS) structure in WLAN device. Objectives to create a band pass square-loop filter FSS in WLAN device to increase the received signal strength of WLAN signal 2.4GHz. FSS works to enhance the 2.4 GHz signal and attenuate the rest signal other than 2.4 GHz. The WLAN signals increasing more than 50 % when pass through the FSS structure.

THE INFLUENCE OF HUMAN HEAD MODEL WEARING METAL- FRAME SPECTACLES TO THE CHANGES OF SAR AND ANTENNA GAIN: SIMULATION OF FRONTAL FACE EXPOSURE

The relationship between specific absorption rate (SAR) and antenna gain inside the head due to the metal-frame spectacles was investigated. The radio frequency (RF) energy source considered is the smartphone used in the frontal face. A computer simulation using CST Microwave Studio 2012 was used for the investigation. Two sets of dipole antennas, operated at 900 MHz and 1800 MHz for GSM applications, were used as representative radiation sources from a mobile phone. Parametric studies were conducted to determine the optimum length of the metal rod, and the length was used to study the possibility of RF irradiation of the metal spectacles model. Then, the spectacles model was used as an analysis tool to study the interaction between gain and SAR in the head. The radiation pattern was plotted to identify the causes of the interactions. The gain decreased when the energy source was very close to the spectacles, and SAR increased enormously.

Optimal Coordinated Design of Multiple Damping Controllers Based on PSS and UPFC Device to Improve Dynamic Stability in the Power System

Unified Power Flow Controller (UPFC) device is applied to control power flow in transmission lines. Supplementary damping controller can be installed on any control channel of the UPFC inputs to implement the task of Power Oscillation Damping (POD) controller. In this paper, we have presented the simultaneous coordinated design of the multiple damping controllers between Power System Stabilizer (PSS) and UPFC-based POD or between different multiple UPFC-based POD controllers without PSS in a single-machine infinite-bus power system in order to identify the design that provided the most effective damping performance. The parameters of the damping controllers are optimized utilizing a Chaotic Particle Swarm Optimization (CPSO) algorithm based on eigenvalue objective function. The simulation results show that the coordinated design of the multiple damping controllers has high ability in damping oscillations compared to the individual damping controllers. Furthermore, the coordinated design of UPFC-based POD controllers demonstrates the superiority over the coordinated design of PSS and UPFC-based POD controllers for enhancing greatly the stability of the power system.