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29,922 Article Results

Study of red-emitting LaAsO4:Eu3+ phosphor for color rendering index improvement of WLEDs with dual-layer remote phosphor geometry

10.12928/telkomnika.v18i6.13637
My Hanh Nguyen; Industrial University of Ho Chi Minh City Thi , Nguyen Thi Phuong; Posts and Telecommunications Institute of Technology Loan , Nguyen Doan Quoc; Ton Duc Thang University Anh
The remote phosphor structure is often disadvantageous in color quality but in terms of optics it is more convenient when compared to other phosphor structures such as conformal or in-cup ones. From this disadvantage, there are many studies to improve its chromatic output. In this research paper, we propose a dual-layer remote phosphor geometry for the improvement of white light-emitting diodes (WLEDs) in two parameters: color rendering index (CRI) and color quality scale (CQS). The 7700 K WLEDs are used in this study. The idea of the study is to place a red phosphor layer LaAsO4:Eu3+ on the yellow phosphor YAG: Ce3+, and then find the concentration of LaAsO4:Eu3+ in an appropriate way to achieve the highest color quality. The results showed that LaAsO4:Eu3+ bring great benefits for enhancing CRI and CQS. In particular, the greater the concentration of LaAsO4:Eu3+, the greater the CRI and CQS because the portion of red lights in WLEDs increases. However, the decrease in lumen output occurs when the concentration of LaAsO4:Eu3+ increases excessively. This is proved thanks to Mie-scattering theory and Beer-Lambert law. The results of important articles in WLEDs fabrication have greatly contributed to a higher white light quality.
Volume: 18
Issue: 6
Page: 3210-3215
Publish at: 2020-12-01

Optimal coordinated design of PSS and UPFC-POD using DEO algorithm to enhance damping performance

10.11591/ijece.v10i6.pp6111-6121
Omar Muhammed Neda
Low-frequency oscillations (LFO) are an inevitable problem of power systems and they have a great effect on the capability of transfer and power system stability. The power system stabilizers (PSSs) as well as flexible AC transmission system (FACTS) devices can help to damp LFO. The target of this study is to tackle the problem of a dual-coordinated design between PSS and unified power flow controller (UPFC) implementing the task of power oscillation damping (POD) controller in a single machine infinite bus (SMIB) system. So, dolphin echolocation optimization (DEO) technique is utilized as an optimization tool to search for optimal parameter tunings based on objective function for enhancing the dynamic stability performance for a SMIB. DEO an algorithm has a few parameters, simple rules, provides the optimum result and is applicable to a wide range of problems like other meta-heuristic algorithms. Use DEO gave the best results in damping LFO compared to particle swarm optimization (PSO) algorithm. From the comparison results between PSO and DEO, it was shown that DEO provides faster settling time, less overshoot, higher damping oscillations and greatly improves system stability. Also, the comparison results prove that the multiple stabilizers show supremacy over independent controllers in mitigationg LFO of a SMIB.
Volume: 10
Issue: 6
Page: 6111-6121
Publish at: 2020-12-01

Emotional exhaustion and organizational commitment: Primary school teachers’ perspective

10.11591/ijere.v9i4.20727
Mozes M. Wullur , Basilius Redan Werang
Teaching is a noble profession to educate the youth of nations facing today’s global challenges. Teaching, at the same time, has become a highly challenging profession and occasionally a draining work, especially for those who are working in the remote areas. A high-level of teacher absenteeism in the primary schools of Southern Papua has blown some societal alarm for conducting studies focusing on emotional exhaustion as a latent predictor for low-performance. This study attempted to describe the eventual correlation between the emotional exhaustion and organizational commitment of teachers working in the primary schools of Merauke, Indonesia. A survey approach was employed to collect data from a total of 243 primary school teachers in Merauke, Papua, Indonesia. Data were examined statistically by employing Pearson’s correlation model. Results of analysis showed that the emotional exhaustion and commitment of primary school teachers in Merauke, Indonesia, are significantly negatively correlated. This result may be useful for the teachers to benefit from the information of how they may interact with all the school elements and the extent to which these emotions directly affect their organizational commitment. The result may also be advisable for the school leaders to take some tactical efforts of securing teachers’ emotion to promote a high-level of teachers’ organizational commitment and, in turn, improving students’ capabilities in reading, writing, and arithmetics.
Volume: 9
Issue: 4
Page: 912-919
Publish at: 2020-12-01

Using position control to improve the efficiency of wind turbine

10.12928/telkomnika.v18i6.16171
Roshen Tariq; University of Technology Ahmedhamdi , Salam Waley; University of Technology Shneen
Wind energy is one of the renewable energies that can be using to generate electricity. Increasing demand for this type of renewable energy for sustainability and accessibility. Environmentally as it does not cause any pollution in addition to the abundance of required equipment and lessmaintenance and long operation life of its parts despite the high cost of the system at its installation but at long term, become cheaper. Wind power generators depend on their operation on wind speed and direction. Therefore,it should be installing in places where the wind speed is adequate and sufficient to rotate its rotor, it knows that wind speed is variable in its speed and direction they change every hour and every season. In this design, many practical and theoretical (simulation) experiments have been done which will be mentioned and explained in details in this research shows that this mechanism raises the efficiency of wind power generators by 80% when the rotor of the wind turbine directed towards the wind than if they were fixed direction.
Volume: 18
Issue: 6
Page: 3240-3246
Publish at: 2020-12-01

Wireless control system for spy devices based dual tone multi frequency technology

10.12928/telkomnika.v18i6.15846
Jabbar Shatti; Dijlah University College Jahlool , Mohammed Abdulla; Dijlah University College Abdulsada
Obtaining information is one of the most important requirements for  intelligence works, spy surveillance cameras and listening devices are among the important means for this. One problem of using these means is a mechanism of controlling them to sustain their work efficiently for the perpetuating of achieving the purpose of their installation. In this research, the problem of controlling these devices has been overcome, by designing asystem dependent on the dual tone multi frequency (DTMF) and global system for mobile(GSM) networks. In the proposed work, designing and  implementing a system to remotely and wirelessly control of the movement of spy cameras in all directions as well as the ability to control the on/off listing audio device anytime and anywhere. The proposed mechanism is implementedby dividing the work into nine modes, with each one performing one specificfunction. These work modes are used to control all system activities such as control the horizontal directional motor (HDM) to change the spy camera in different horizontal directions, control the vertical directional motor (VDM) to change the camera in vertical directions and control the working status of the listening device.
Volume: 18
Issue: 6
Page: 3107-3115
Publish at: 2020-12-01

An experimental study on performace of starch extracted from wheat flour as filtration control agent in drilling fluid

10.11591/ijaas.v9.i4.pp255-260
Raheel Iqbal , Fawad Pirzada , Muhammad Zubair , Ameer Mehmood
The phenomenon of lost of mud filtrate into a porous permeable formation due to high hydrostatic pressure compared to the formation pressure is known as fluid loss. This cause some major problems in well during drilling as poor cementing job, pipe stuck, and formation damage. Thus, to safe the well from such problems and in order to make safe and effective drilling an additive from wheat flour is extracted which is starch, and acting as a fluid loss control agent. The purpose of this research is to investigate the potential of utilizing this additive to form environmentally safe, non-toxic, high biodegradability and low-cost water-based drilling fluid samples with varying the amount of starch. Experimental results showed that Efficiency of starch obtained from wheat-flour is showing increment in rheological properties as compare to starch present in market by using same and varying quantity of both and observed that wheat-flour starch is more efficient as compare to starch in market. On the other hand, the efficiency of starch is good but it has been also improved by the extraction of starch from wheat-flour by the centrifugation process.
Volume: 9
Issue: 4
Page: 255-260
Publish at: 2020-12-01

Comparative analysis of PID and neural network controllers for improving starting torque of wound rotor induction motor

10.12928/telkomnika.v18i6.14571
Hashmia Sh.; University Of Technology Baghdad Dakheel , Zainab B.; University Of Technology Baghdad Abdulla , Helen Jasim; University Of Technology Baghdad Jawad , Ali Jasim; Ministry of education/Directorate of vocational education Mohammed
Unlike 3-phase squirrel cage induction motor, starting-up of 3-phase wound rotor counter part can be improved by adding an external resistance to the rotor circuit.Thus, leads to reduce starting current and increase starting torque. In this paper two controllers for 3-phase wound rotor induction motor have been proposed include conventional proportional integral derivative (PID)  controller and the other based on artificial neural network (NARMA-L2). A comparison between these controllers has been conducted. It has been shown that starting torque of the motor has been improved, when utilizing the neural network controller compared to the conventional counter  part. It should be noted that MATLAB/SIMULINK has been used to implement both controllers.
Volume: 18
Issue: 6
Page: 3142-3154
Publish at: 2020-12-01

Design and software implementation of radio frequency satellite link based on SDR under noisy channels

10.12928/telkomnika.v18i6.16130
Ahmed A.; Al-Rafidain University College Thabit
The satellite communication providea utilization of radio frequency links. Specific frequencies are dedicated for satellite correspondences through global administrative and coordination procedures which keeps impedance amongframeworks. Over typical work, the satellite receives uplinked indicator fromearth. Progressions its frequency marginally will keep away from self-intervention then re-transmits signal ahead the downlink on the land. Pathloss depicts characteristic Propagate outside the sending signal front as it goes bythe space. A  software defined radio (SDR) is a flexible technology that aimsto replace all hardware by software to enables the design of adaptive communications systems such as changing frequencies, modulation schemes and data rates. Applied to small satellites, some of the implications areincreased data through put when down-linking or up-linking by varying communications parameters and making use of one hardware design and implementation for communicating for many missions, just by updating the software. Therefore, development time for small satellite communication systems can be reduced in the future. This paper analyzes, design and software implementation of radio frequency satellite communications links under noisy channels such as phase/frequency offsets and noise temperature. Modulation schemes such as 64QAM system is used based on Matlab tools to implement the results. Obtained results shows a good response that get the goal from the paper.
Volume: 18
Issue: 6
Page: 2852-2860
Publish at: 2020-12-01

Perceptions and experiences of students on the use of interactive online learning technologies in Mauritius

10.11591/ijere.v9i4.20692
Parmeswar Ramkissoon , Louis Jinot Belle , Trishnee Bhurosy
With the advent of e-learning, advocates use the term interactivity instead of interaction among students, and between the teacher and the students. Many universities use Moodle for online teaching and learning. This paper explores the perceptions and experiences of students in three Higher Education Institutions (HEIs) in Mauritius. A mixed-methods approach was used, with an online survey questionnaire administered to 600 students and focus group discussions were conducted with 15 students from these institutions. It was found that 68.4% of respondents used WhatsApp compared to only 23.6% of them who used the e-learning platform, Moodle. There were no associations between the use or frequency of using WhatsApp or Facebook and the types of HEI to which the students belonged. Students preferred WhatsApp due to its facility for knowledge sharing and construction, its interactivity, its usability, respect for privacy and instant communication. From the findings, it is recommended that HEIs bring a shift in their approaches to teaching and learning from cognitivism to socio-constructivism, connectivism and heutagogy.
Volume: 9
Issue: 4
Page: 833-839
Publish at: 2020-12-01

Automatic control system of highway lights

10.12928/telkomnika.v18i6.16497
Yasir; Tishk International University Hashim , Mohammed Nazmus; Universiti Malaysia Pahang Shakib
This research provides new effective and cheap designed system for save electrical energy dissipation in all urban area roads and highways. The aim of this system is to minimizing the waste electrical power on highways and urban  area roads. The designed system depends on two Arduino circuit types, master and slave. The master  Arduino has an ability to detect the day light by light dependent resistor (LDR) sensor and cars movements by pyroelectric infrared (PIR) sensor, according to these conditions, the master will send a signal by XBee module works as transmitter to the following five slaves  Arduino which are waiting for a signal and receive it by XBee module works as receiver to turn ON the lights for 5 minutes then OFF it if there is no car movement on the street. The system can mount directly to the highway lights. The system has been tested and applied on the street lights, the system works perfectly and slaves respond fastly and effectively to the master Arduino signal.
Volume: 18
Issue: 6
Page: 3123-3129
Publish at: 2020-12-01

A systematic review of text classification research based on deep learning models in Arabic language

10.11591/ijece.v10i6.pp6629-6643
Ahlam Wahdan , Sendeyah AL Hantoobi , Said A. Salloum , Khaled Shaalan
Classifying or categorizing texts is the process by which documents are classified into groups by subject, title, author, etc. This paper undertakes a systematic review of the latest research in the field of the classification of Arabic texts. Several machine learning techniques can be used for text classification, but we have focused only on the recent trend of neural network algorithms. In this paper, the concept of classifying texts and classification processes are reviewed. Deep learning techniques in classification and its type are discussed in this paper as well. Neural networks of various types, namely, RNN, CNN, FFNN, and LSTM, are identified as the subject of study. Through systematic study, 12 research papers related to the field of the classification of Arabic texts using neural networks are obtained: for each paper the methodology for each type of neural network and the accuracy ration for each type is determined. The evaluation criteria used in the algorithms of different neural network types and how they play a large role in the highly accurate classification of Arabic texts are discussed. Our results provide some findings regarding how deep learning models can be used to improve text classification research in Arabic language.
Volume: 10
Issue: 6
Page: 6629-6643
Publish at: 2020-12-01

Enhancement in resource allocation system for cloud environment using modified grey wolf technique

10.11591/ijeecs.v20.i3.pp1530-1537
Soukaina Ouhame , Youssef Hadi
Cloud computing is new trend of technology which provides services with the help of internet based on specific rules.VM is one of the main elements of cloud computing it work on virtualizations concept. Due to the growth of cloud computing user demands for better service are increasing and it make different kind of issues in cloud environment. Data allocation sysytem in VM is one of them for that reason in this paper a new technique used for improvment of data allocation system in VM for cloud computing. The improvement took place GWO algorithm two main section of this algorithm are modified which are local search section and fitness function value. The above proposed technique used to improve three main parameter of scheduling which are energy consumption, throughput and average network executation time in VM for cloud computing. The proposed technique result are compare with ABC algorithm and GWO algorithm based on those result the proposed algorithm improved the three main parameter of load balancing technique in cloud computing.
Volume: 20
Issue: 3
Page: 1530-1537
Publish at: 2020-12-01

Machine learning algorithms for fall detection using kinematic and heart rate parameters-a comprehensive analysis

10.11591/ijai.v9.i4.pp772-780
Anita Ramachandran , Adarsh Ramesh , Aditya Sukhlecha , Avtansh Pandey , Anupama Karuppiah
The application of machine learning techniques to detect and classify falls is a prominent area of research in the domain of intelligent assisted living systems. Machine learning (ML) based solutions for fall detection systems built on wearable devices use various sources of information such inertial motion units (IMU), vital signs, acoustic or channel state information parameters. Most existing research rely on only one of these sources; however, a need to do more experimenation to observe the efficiency of the ML classifiers while coupling features from diverse sources, was felt. In addition, fall detection systems based on wearable devices, require intelligent feature engineering and selection for dimensionality reduction, so as to reduce the computational complexity of the devices. In this paper we do a comprehensive performance analysis of ML classifiers for fall detection, on a dataset we collected. The analysis includes the impact of the following aspects on the performance of ML classifiers for fall detection: (i) using a combination of features from 2 sensors-an IMU sensor and a heart rate sensor, (ii) feature engineering and feature selection based on statistical methods, and (iii) using ensemble techniques for fall detection. We find that the inclusion of heart rate along with IMU sensor parameters improves the accuracy of fall detection. The conclusions from our experimentations on feature selection and ensemble analysis can serve as inputs for researchers designing wearable device-based fall detection systems.
Volume: 9
Issue: 4
Page: 772-780
Publish at: 2020-12-01

Color image encryption based on chaotic shit keying with lossless compression

10.11591/ijece.v10i6.pp5736-5748
Ashwaq T. Hashim , Bahaa D. Jalil
In order to protect valuable data from undesirable readers or against illegal reproduction and modifications, there have been various data encryption techniques. Many methods are developed to perform image encryption. The use of chaotic map for image encryption is very effective, since it increase the security, due to its random behavior. The most attractive feature of deterministic chaotic systems is he extremely unexpected and random-look nature of chaotic signals that may lead to novel applications. A novel image encryption algorithm based on compression and hyper chaotic map techniques is proposed. Firstly the image is decomposed into three subbands R, G, and B then each band is compressed using lossless technique. The generated chaotic sequences from the 3D chaotic system are employed to code the compressed results by employing the idea of chaotic shift encoding (CSK) modulation to encode the three bands to generate the encrypted image. The experiments show that the proposed method give good results in term of security, feasibility, and robustness.
Volume: 10
Issue: 6
Page: 5736-5748
Publish at: 2020-12-01

Improving optical properties of remote phosphor LED using green Y2O3:Ho3+ and red Mg4(F)(Ge, Sn)O6:Mn2+ layers

10.12928/telkomnika.v18i6.13797
My Hanh Nguyen; Industrial University of Ho Chi Minh City Thi , Nguyen Thi Phuong; Posts and Telecommunications Institute of Technology Loan , Nguyen Doan Quoc; Ton DucThang University Anh
The lighting device that employs diodes to create white light (WLEDs) with quantum dots (QDs) and phosphor layers is a promising lighting method that is increasingly used in many fields on account of the remarkable color expressing ability. The QDs film is usually placed apart from the phosphor layer according to the packaging configuration to prevent light loss due to backscattering as well as preserve the consistency of the ligands on the QDs surface. The article also conducted experiments to compare the lighting properties and thermal output of the two packaging orders of QDs and phosphor. The heat discharing ranges were simulated with thermography technology, moreover, other parameters such as light energy emission and PL spectra are acquired to evaluate the efficiency of the packaging order. The results from the practical experiment show that while under 10% wt., the luminous output (LO) of green QDs-on-phosphor structure reaches 1130 lm, higher than the red QDs-on-phosphor structure with 878 lm, and the color rendering value in the configuration with red QDs on phosphor is Ra = 74 are higher than Ra = 68 index of the green QDs-on-phosphor structure. As a result, the QDs-on-phosphor is determined as the better packaging configuration to choose to achieve an overall improvement in lighting efficiency, color rendering index
Volume: 18
Issue: 6
Page: 3228-3233
Publish at: 2020-12-01
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