Bow-Tie Microstrip Antenna Design

In this paper, the bow-tie microstrip antennas have been designed with two different angles of 40° and 80°. An investigaton on the effect of the angle to the return loss and radiation patterns had been carried out. The impedance matching network with the niicrostrip transmission line feeding was used in this study. Simulation and measurement results for the return loss and radiation patterns were presented

Foundations on Stone Columns Resting on Coralline Limestone

The subsoil conditions along the Red Sea coast in Saudi Arabia are complex due to existence of very thick beds of coralline limestone of recent geological origin. These coral beds are soft, porous and nonhomogeneous. They are often interspaced with large cavities and soft sandwiched layers of finer particles. Analysis of the subsoil conditions to a fifty meter depth based on data from deep boreholes, Standard Penetration Tests (SPT), Quasi Static Cone Tests (DCT) and large size Plate Load Tests is presented. The strength and compressibility characteristics of the strata and the correlation factors for the SPT and DCT in coralline limestone are evaluated. The results from the plate load tests conducted on natural soil and on soil compacted with stone columns are included. An evaluation of the performance of the foundation for the heavy turbines resting on soil compacted with vibro-compaction replacement method with stone columns was made

Optimum transmitter receiver ratio for maximum wireless energy transfer

Due to high demand of using cordless mobile device, the interest in wireless energy transfer (WET) has been growth intensively. This paper presented a method to obtained optimum transmitter receiver ratio for maximum performance of WET system using different initial antenna size at various distance. An optimized algorithm has been developed to determine the optimum ratios that yield the highest wireless transfer efficiency (WTE) at near field communication (NFC) frequency, 13.56MHz. 30mm × 30mm single square loop antenna is used as initial size of both transmitter and receiver using FR4 with operating distance = 50mm. Operating distance and initial size of the antenna will be varied and the effect to the WTE will be studied using Matlab, verified using Microsoft Studio CST. At distance = 50mm and initial size of the antenna = 30mm × 30mm, optimum transmitter to receiver ratio equal to 1:3 is obtained. The pattern of optimum transmitter receiver ratio between Matlab and CST has met an agreement. This research limited to integer transmitter receiver ratio used only and no decimal number being involved in magnify the transmitter size

Textile Diamond Dipole and Artificial Magnetic Conductor Performance under Bending, Wetness and Specific Absorption Rate Measurements

Textile diamond dipole and Artificial Magnetic Conductor (AMC) have been proposed and tested under wearable and body centric measurements. The proposed antenna and AMC sheet are entirely made of textiles for both the substrate and conducting parts, thus making it suitable for wearable communications. Directive radiation patterns with high gain are obtained with the proposed AMC sheet, hence minimizing the radiation towards the human body. In this study, wearable and body centric measurements are investigated which include bending, wetness and Specific Absorption Rate (SAR). Bending is found not to give significant effect to the antenna and AMC performance, as opposed to wetness that yields severe performance distortion. However, the original performance is retrieved once the antenna and AMC dried. Moreover, notable SAR reduction is achieved with the introduction of the AMC sheet, which is appropriate to reduce the radiation that penetrates into human flesh

Mountain-Shaped Coupler for Ultra Wideband Applications

This paper demonstrates a novel mountain-shaped design for a compact 3-dB coupler operating at ultra-wideband (UWB) frequencies from 3.1GHz to 10.6 GHz. The proposed design was accomplished using multilayer technology in which the structure is formed by three layers of conductors interleaved by a layer of substrate between each conductor layer. Simulation was carried out using CST Microwave Studio; the result was then compared with results from rectangular and star-shaped couplers that implemented the same technique. The results obtained show that the proposed new coupler has better performance compared to both rectangular and star-shaped coupler designs in terms of return loss, isolation, and phase difference. The coupler was fabricated and measured; the measurement results satisfactorily agree with the simulation results

DG-Embedded Radial Distribution System Planning Using Binary-Selective PSO

With the increasing rate of power consumption, many new distribution systems need to be constructed to accommodate connecting the new consumers to the power grid. On the other hand, the increasing penetration of renewable distributed generation (DG) resources into the distribution systems and the necessity of optimally place them in the network can dramatically change the problem of distribution system planning and design. In this paper, the problem of optimal distribution system planning including conductor sizing, DG placement, alongside with placement and sizing of shunt capacitors is studied. A new Binary-Selective Particle Swarm Optimization (PSO) approach which is capable of handling all types of continuous, binary and selective variables, simultaneously, is proposed to solve the optimization problem of distribution system planning. The objective of the problem is to minimize the system costs. Load growth rate, cost of energy, cost of power, and inflation rate are all taken into account. The efficacy of the proposed method is tested on a 26-bus distribution system

RF Energy Harvesting Study Using Various Metamaterial Patch Structure

The E-field absorbance performance of various metamaterial absorber structure is presented. The study started from the simulation of various design patch of metamaterial absorber. The performances are measured from the reflection coefficient, percentage of absorption, value of E-field and the surface current for circle, square and hexagon patch design of metamaterial absorber. From the simulation, it is shown that the circle patch design shows the most reliable design for harvest energy with the absorption of 99.85% and highest E-field concentration of 2.07 × 105 V/m

Textile diamond dipoles for body centric communications at 2.45GHZ and 5.8GHZ

This study proposes textile diamond dipoles for body centric communication that operate at 2.45GHz and 5.8GHz. The proposed antennas have been rigorously tested under wearable and body centric measurements. Both substrates and conducting parts of the diamond dipoles are entirely made of textiles; which is deemed fit for wearable communications. Experiments such as bending, wetness and SAR were performed to investigate the antennas' performance for body communication realization. Bending was found not to cause any significant performance disruption. On the other hand, since the proposed antenna is not made of water-proof material, the performance was distorted under wet condition. However, once the antenna was dried out, the original performance was achieved. SAR measurement was also conducted and significant SAR values were observed when placing the proposed diamond dipoles close to human body

Isolation of enterotoxigenic, hemolytic, and antibiotic-resistant Aeromonas hydrophila strains from infected fish in Bangladesh

Strains of Aeromonas hydrophila isolated from skin infections of common freshwater fish in Bangladesh were tested for enterotoxin production, hemolysin production, and any correlation between these two activities. We also tested the resistance patterns of A. hydrophila to different drugs, especially in relation to ampicillin. The A. hydrophila strains produced an enterotoxin that was related to their beta-hemolytic activities. Production of beta-hemolysin may thus be an indicator of enterotoxicity. As 50% of the strains of A. hydrophila were found to be susceptible to 12.5 µg of ampicillin per ml, media containing this antibiotic may not be suitable for their isolation

Time series forecasting of the number of Malaysia Airlines and AirAsia passengers

The standard practice in forecasting process involved by fitting a model and further analysis on the residuals. If we know the distributional behaviour of the time series data, it can help us to directly analyse the model identification, parameter estimation, and model checking. In this paper, we want to compare the distributional behaviour data from the number of Malaysia Airlines (MAS) and AirAsia passenger’s. From the previous research, the AirAsia passengers are govern by geometric Brownian motion (GBM). The data were normally distributed, stationary and independent. Then, GBM was used to forecast the number of AirAsia passenger’s. The same methods were applied to MAS data and the results then were compared. Unfortunately, the MAS data were not govern by GBM. Then, the standard approach in time series forecasting will be applied to MAS data. From this comparison, we can conclude that the number of AirAsia passengers are always in peak season rather than MAS passengers