Journal of Engineering and Technology (JET)

Table of Contents Vol. 10 No. 2 (2019)

2022-08-09T08:58:00+00:00

Table of Contents Vol. 10 No. 2 (2019)

Power Quality Improvement Using Series Active Power Filter Based On Gravitational Search Algorithm

2021-12-21T17:35:01+00:00

This 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.

A Study To Analyze Impact Of Whatsapp On Emotional Health Society

2021-12-21T17:35:01+00:00

with an enormous growth in the number of users for social media, it becomes important to understand its impact on the society. This paper is a small step in this direction by analyzing the impact of social media on the emotional health of its users. The paper in particular focuses on the impact of WhatsApp usage. In the study authors have focused their research on 98 users. In this survey authors found that WhatsApp has a significant impact on the humans these days. Some findings during this study are alarming and needs to be controlled. It is noticed during the survey that WhatsApp has greatly influenced the life style of its users and therefore its usage should be monitored and controlled to avoid any adverse affect on emotional health of its users.

Solar Radiation Estimation For Modelling High Performance Photovoltaic System Designs

2021-12-21T17:35:01+00:00

Estimation of solar radiation levels involves various techniques such as using data obtained from weather stations, commercial softwares, and mathematical models which cover a wide range of forms within. The limited number of weather stations as well as the cost of required equipment result in higher interest in taking advantage of estimation models due to their time and cost efficiency. However, such models heavily depend on the characteristics of the specific region to be analyzed. Geographic and climatic conditions make significant differences in terms of model accuracy. This study involves model selection for two cities in the third climatic region of Turkey and calculating the solar radiation characteristics both on horizontal and inclined surfaces. The obtained results carry the potential of serving as an integral part of constructing country-wide model for solar radiation estimation.

T-S Controllers For Photovoltaic-Grid Connected System Through DC-DC Boost Converter and Three Phase Inverter

2021-12-21T17:35:01+00:00

Ce document présente deux contrôleurs flous TS en ligne pour contrôler l'extraction de puissance optimale et son transfert du système PV via deux convertisseurs statiques vers le réseau public. Le premier contrôleur est appliqué sur le convertisseur élévateur pour calculer, à chaque instant, le rapport cyclique permettant de suivre le point de puissance maximale du panneau sous les variations climatiques et d'atteindre un rendement élevé pour la récolte d'énergie solaire. Alors que le second ajuste les états de commutation des branches de l'onduleur triphasé à deux niveauxtransistors pour un transfert maximal de la puissance active produite par le panneau vers le réseau de distribution avec compensation de puissance réactive lors de l'établissement de la synchronisation.Après présentation de la structure du système de connexion au réseau et modélisation mathématique des convertisseurs côté PV et côté réseau, les contrôleurs flous TS sont détaillés. La synthèse de ces contrôleurs est basée sur la subdivision de l'espace d'états du système non linéaire à contrôler en un ensemble de sous-systèmes linéaires. Pour assurer le rejet des perturbations et garantir la stabilité du contrôleur flou, Le critère et la fonction de stabilité quadratique de Lyapunov sont considérés. Les gains du contrôleur sont calculés en utilisant la solution d'inégalité de matrice linéaire (LMI). Les résultats de la simulation numérique sur l'environnement Matlab-Simulink montrent l'efficacité et les performances des contrôleurs proposés.

Risk Identification And Analysis Of Precast Concrete Structure Based On Work Breakdown Structure-Risk Breakdown Structure

2021-12-21T17:35:01+00:00

Because the prefabricated building started late in China, and subject to management and technical restrictions, the safety problems during the construction of the prefabricated building have not been solved effectively. In view of the problems of complex environments in precast concrete structure and many influencing factors which makes the construction risks are difficult to identify. The work breakdown structure (WBS) - risk breakdown structure (RBS) method is introduced to solve the problem. By means of analyzing the investigation data of the prefabricated building accidents, its risks during construction are identified and coupled. Then the judgment matrix is obtained and the corresponding risk factors can be established. In the meanwhile, the fault tree analysis method has been being used to analyze the sensitivity of three kinds of accidents, such as falling, striking by object and electrocution. The sensitive coefficients of risk factors are calculated and sorted. The result shows that the main risk factors of falling accident are verticality deviation of component installation, deviation of component position and unsecured mechanics. The main risk factors of striking by object/equipment are insufficient strength of components supporting, overturning components and unreasonable of suspension point. The main risk factors of electrocution are improper welding operation and short circuit. Finally, corresponding control measures are put forward according to the risk accidents. The research results provided a good theoretical basis for the risk identification of prefabricated building construction.

Metric-Based Random Iteration Algorithm For Resource Management In Non-Orthogonal Multiple Access Of Wireless Networks

2021-12-21T17:35:01+00:00

In this paper, we focus on joint subcarrier and power allocation in the uplink of an NOMA system. The main taxonomy of NOMA is presented by focusing on the following categories: power-domain and code-domain NOMA. Then a novel radio resource management framework is presented metric-based random iteration Algorithm (MRIA) for uplink and downlink transmissions. This method determine target subject that it is Number of scheduled users.

Dehydration Characteristics of Taro Root (Colocasia Esculenta) Slices using a Refractance WindowTM Dryer

2021-12-21T17:35:01+00:00

This report presents the dehydration characteristics of Taro (Colocasia esculenta) root slices dried at 65, 75, 85 and 95oC in a fabricated laboratory scale Refractance WindowTM dryer; the Taro root slices were 3.0, 4.5 and 6.0 mm thick. Moisture content and water activity variation data were taken during the drying operation for the process conditions selected. For the process conditions studied, the times required to dehydrate the moisture content to 0.11 g-water/g-solid varied between 55 to 260 minutes. For a given slice thickness, the drying times to reach the 0.11 g-water/g-solid moisture content decreased as the drying temperature increased. Also, for a given drying temperature, the drying times required to reach the 0.11 g-water/g-solid moisture content increased with slice thickness. The effective moisture diffusivity varied from 8.14 x 10-08 to 9.53 x10-07 m2/s for the process conditions studied. While moisture diffusivity data on the Refractance WindowTM dryer, was not found in the literature, the moisture diffusivity values estimated, were within the range observed for other equipment. The moisture diffusivity parameters determined in this study, are important because they are useful in the design, modelling, and optimisation of such dryers.

Computational Fluid Dynamic Simulation: Maximise The Percentage Of Air Distribution Inside Quasi-Flow Heat Exchanger

2021-12-21T17:35:01+00:00

Parallel plate quasi-flow air-to-air heat exchanger has been implemented in Heat Recovery Ventilation (HRV) system to enhance the operating efficiency even in small temperature difference. In the HRV system, heat energy from the exhaust air is recovered to pre-treat the fresh air coming into the air-conditioning systems. Therefore, the HRV system can reduce the power consumption of Heating, Ventilation and Air Conditioning (HVAC) systems by enhancing the performance of the HRV system. Air velocity distribution over the plate of heat exchanger has a strong effect on the HRV system performance. The higher the percentage of area covered with air across the plate, the higher the heat transfer rate between two airstreams.

Inside the plate of the heat exchanger, duct inlet entrance causes air distribution to be non-uniform. Factor affecting air velocity distribution over the plate is investigated to reduce air velocity maldistribution. A simulation using ANSYS is conducted to investigate the effect of different louvres arrangements on the air velocity distribution across the plate of the heat exchanger. Results show that, with a smaller louvre orifice, Mode 1 performs best in term of air velocity distribution, and Turbulence Kinetic Energy (TKE) intensity due to turbulence flow generated at louvre arrangement and complement the effect of pressure drop across the plate. Mode 1 enhances the performance of the HRV system by increasing the percentage of air distribution across the plate with an approximation of 97%.

Knowledge Of Ergonomics Among Technical Staff In University Technology Mara Penang Malaysia

2021-12-21T17:35:01+00:00

Ergonomics is the scientific study of human work. Ergonomics knowledge helps in its right application and contributes significantly to the general wellbeing and safety worker’s at the workplace. Even though ergonomics in Malaysia was introduced in 1992, but it is a relatively new concept and yet to be considered an essential component of most enterprises. The aim of this study is to evaluate the level of ergonomics knowledge among technical staff in University Technology MARA (UiTM), Penang Malaysia. A questionnaire was developed and distributed to all technical staff of UiTM and the responses were analyzed using SPSS version 15. The evaluation showed that the score of average mean and standard deviation obtained are 3.16 and 0.96 respectively. The result shows that their level of ergonomic knowledge is moderate. The mean score obtained from the awareness of the effect if the ergonomics aspects are not practiced in the workplace is 4.37 which is a high level. It means that they don`t want to get injured and experience an unhealthy condition in the workplace. Regular ergonomic educations and practices in UiTM are advocated to increase ergonomics knowledge and practice to better level

Bibliometric Analysis Of Agile Software Development

2021-12-21T17:35:01+00:00

Agile methodologies are currently considered one of the main paradigms of software development. Its study, from a scientific point of view, has deserved prominence in recent years by the scientific community related to the area of software engineering. This study intends to perform a bibliometric analysis of the quantity, characteristics and scope of the most relevant studies published in this area of knowledge. The findings indicate that the number of studies published from 2010 to 2016 significantly increased, having reached a peak in 2015. The study identifies the main journals and conferences in the field and we also concluded that the majority of published studies are literature reviews of agile software development, and qualitative and quantitative research methods have identical number of publications.

Investigation On The Interaction Analysis Of Beam-Nonlinear Isolator With Low And High Stiffness Support

2021-12-21T17:35:01+00:00

This paper presents the study of the interaction between a beam and a nonlinear isolator for low and high supporting stiffness. The system consists of an elastic beam- like structure and a geometrically nonlinear isolation system in which a horizontal degree provides a physical approach for realising the required horizontal force. The generalised dynamic equations of the system are derived and the modal summation method is used to analyse the beam. The dynamic interaction mechanism between the nonlinear isolation system and the elastic structure is revealed. The beam- nonlinear isolator design for low stiffness support and high stiffness support is discussed. It is found that the beam provides additional mass, stiffness and force to the nonlinear vibration isolator and the requirement to perform ground vibration test whereby the rigid mode of the beam must be less than one third of the first elastic natural frequency of the free-free beam has been satisfied. The condition to achieve high stiffness support has also been satisfied. Nonlinear dynamical behaviour of the beam-nonlinear isolator indicates that period doubling bifurcation occurs when the excitation force is 1 and excitation frequency is 0.5Hz. Poincare’ maps reveals that the system form closed loops and no chaotic behaviour is observed. Perfomance analysis in terms of force transmissibility of the nonlinear isolator shows that the nonlinear isolator performs better than a linear isolator and also performs better than a hardening HSLDS mount.