Universiti Teknikal Malaysia Melaka: UTeM Open Journal System
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Power Quality Improvement Using Series Active Power Filter Based On Gravitational Search Algorithm
Get PDFThis paper proposes a heuristic control of the series active power filter for power quality enhancement. In this context, the series active filter is better utilized as a voltage source controller contrary to its conventional usage as variable impedance. The present-day utility system as a linear model is unsatisfactory and the steps are laid down to discuss utility system as a nonlinear model. This paper deals power quality disturbances like voltage sag/swell, voltage error and THD with robust heuristic algorithms like the gravitational search algorithms (GSA) and it is further compared with firefly (FF) algorithm. The harmonic reduction in the source current and mitigation of sags/swells in the load voltage is carried out with optimal tuning of the PI controller. The series active power filter as a harmonic suppressor with a specific reference controlled strategy is discussed in this paper. The synchronous reference frame (SRF) theory is used to generate the reference voltage signals required for compensation. The hysteresis band current controller (HBCC) is used to perform the switching operation of Voltage Source Inverter. Simulations are carried out in the MATLAB/SIMULINK environment
Applying ANFIS Model in Decision-making of Vertical Handover between Macrocell and Femtocell Integrated Network
Get PDFOne of the most challenging tasks in communication networks is to maintain seamless mobility and service continuity during a vertical handover. This paper provides the case of handover decision making between femtocell and macrocell integrated network considering several input parameters, namely SINR, bandwidth and energy consumption. We have simulated and proposed a vertical handover based on adaptive neuro-fuzzy inference system (ANFIS) to achieve a goal of having an intelligent handover and to predict the best destination network. The simulation results show that the approach based on ANFIS leads to a reduction of unnecessary handovers and a minimization of the energy consumption as compared to the existing approaches
SOLDERING CHARACTERISTICS AND THERMO- MECHANICAL PROPERTIES OF Pb-FREE SOLDER PASTE FOR REFLOW SOLDERING
Get PDFA deep understanding in thermal characteristics of lead-free solder paste grades is one of the most crucial factors when dealing with reflow soldering process. These temperatures are critical parameters for proper settings of the real reflow process. This report is devoted to discussing the findings obtained during utilization of differential scanning calorimetry (DSC) and calculation using MATLAB to identify the latent heat, solidus and liquidus temperature, and surface tension applicable to numerically simulate the real process of reflow soldering. It can be stated that the equilibrium solidus and liquidus temperatures during solidification process are not a reversal of the melting process, with the solid phase equilibrium occurred at a lower temperature due to the difficulty of ß-Sn nucleation. Amount of heat energy released during solidification differs less than 10% for SAC405 and less than 1% for SAC105 with the latent heat of fusion during the melting process
Low Phase Noise Wide Tuning Range LC Oscillator for RF Application Using Varactor Bank.
Get PDFThis paper presents the design of a QVCO (Quadrature voltage controlled oscillator) with high tuning range and low phase noise for Radio Frequency applications. The proposed VCO has been designed to produce quadrature signal by using cross coupled topology. Extra pair of MOSFETS are added to improve the quality factor of the LC tank, which helps to improve the phase noise. The tuning range of VCO ranges from 3.8 GHz to 4.52 GHz, which is nearly 20%. Additionally, the obtained phase noise is -120.31 dBc/Hz at 1MHz offset frequency. The observed power dissipation is 13.21 mW
Thermal Performance Analysis of Nano Enhanced Paraffin Wax and Myristic Acid
Get PDFIn the present study, Paraffin wax and Myristic acid were chosen as PCM for the analysis. Further, nanoparticles of copper and micro particles of aluminium and Graphite were used for the analysis of enhancement in thermal performance of PCMs. Charging and storing period analysis have also been conducted to compare the performance of different composites. From the charging period analysis, it has been found that Graphite composites are performing better than copper and aluminium composites. From the both charging and storing period analysis, among composites of Paraffin wax, both 1% copper and 1% graphite composites are giving more satisfactory results than all other composites of paraffin wax and among composites of Myristic acid, it can be concluded that graphite composites are giving more satisfactory results than all other composite, in which 3% graphite is the optimum composition
Effect of Line Width and Thickness on Flexible Printed Electronic Circuit Electrical Performance
Get PDFFlexible and printable electronics is among the rapidly growing field in many applications. Their performances are affected by many factors such as the interaction between the conductive ink circuit and the type of flexible substrate used as the printed board. In this paper, the effect of the conductive ink circuitry line width and thickness to the flexible printed electronic (FPE) electrical performance is investigated. Commercial type carbon based conductive ink and polyethylene terephthalate (PET) flexible substrate were applied to formulate the FPE circuit, using screen printing technique and cured at room temperature, with varying circuitry line width (between 1.00 mm to 3.00 mm) and thickness (between 0.05 mm to 0.25 mm). The final resistivity for all samples were later tested using digital multimeter. Results for the experiments showed that the electrical resistivity of the FPE samples were alost inversely proportional to the dimension of the circuit thickness and width. The results obtained shall be used in the next project stage as benchmarking data to establish design guidelines related to circuitry geometrical parameters to obtain optimum FPE electrical performance in actual application
The Mediating Effect of Innovation on The Relationship between Strategic Management Dimensions and Construction Project Development: A Conceptual Framework
Get PDFInnovation becomes a crucial factor to the project development; a factor which is ignored by the previous strategic management models that focused more on the physical resources of the project. This paper aims to investigate the improvement of the linkage in between the competitive advantages’ roots and the projects’ development. A comprehensive review has been done wherein several previous strategic management models are discussed. The reviews found out that there are some pillars of strategies that contribute to the project development. Even more, this review focuses on how to strengthen the direct relationship between the competitive advantages’ roots and the project development. This paper is significantly important because it adds innovation factor as a mediator between the competitive advantages and the project’s development. Hence, this paper provides an effective project development model linkage for the project’s strategic plan.Keywords—Competitive advantages; resources; value; capability; innovation; project developmen
Performance of Standard and Customized Search Interfaces
Get PDFThe research conducts a performance comparison between standard search interfaces available in modern search engines with a customized search interface that allows the user to change the way the information is presented on the screen. The tested hypothesis is that customized search interface results in a decrease in total search time and increase (or the same amount) of successful searches. Customizable options included font, background, help, tool tips, highlights, preview text and Boolean operators. Based on the performed study customized interfaces allowed users to increase the speed of obtaining correct search results by 10.2%. The benefit comes with a cost of time that users spend to configure the interface. Further research is recommended to both test the results on wider audiences, and test additional customization options
A New Structure of Stereo Algorithm Using Pixel Based Differences and Weighted Median Filter
Get PDFThis paper proposed a new algorithm for stereo vision system to obtain depth map or disparity map. The proposed stereo vision algorithm consists of three stages, matching cost computation, disparity optimization and disparity refinement. The first stage starts with matching cost computation, where pixel based differences methods are used. The matching methods are the combination of Absolute Difference (AD) and Gradient Matching (GM). Next, the second stage; disparity optimization utilizes Winner-Takes-All (WTA) technique to normalize the disparity values of each pixel of the image. Finally, for disparity refinement stage, weighted median (WM) filter is added to reduce and smother the noise on the disparity map
Comparative Analysis between OFDMA and SC-FDMA: Model, Features and Applications
Get PDFThis paper represents Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SCFDMA) techniques along with the Orthogonal Frequency Division Multiplexing (OFDM). The concept, model, features, scopes, applications and limitation for both types of multiple access have been discussed in this paper. In present 4G and 5G cellular communication system, both OFDMA and SC-FDMA have a notable applications. Dividing the available spectrum into overlapping orthogonal narrowband sub bands, OFDMA ensures high spectral efficiency. Besides by allocating multiple sub carriers to each user, OFDMA provides high data rate, reduces inter blockage interference, minimizes frequency selective fading and so on. But it suffers from high peak to average power ration (PAPR) which results in high power consumption at the transmitter end. SC-FDMA is one of the most promising techniques to solve the PAPR problems. Besides it also removes the capacity problem of wireless cellular systems and provides higher spectral efficiency, depending on multiplexing signals based on their spatial signature. On the other hand, in OFDM due to fixed subcarrier allocations for each user and its performance can suffer from narrowband fading and interference