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29,922 Article Results

Analysis of HVDC breakdown characteristic of LLDPE-natural rubber added with biofiller as high voltage insulating material

10.11591/ijeecs.v20.i3.pp1203-1209
Nor Izzati Mohd Salleh , Nor Akmal Mohd Jamail , Nishanti Suntharasaka , Nor Shahida Mohd Jamail , Mohamad Farid Sies , Qamarul Ezani Kamarudin , Mohamed Afendi Mohamed Piah
The influence of solid insulation has been investigated by few researchers. The mechanism of solid breakdown is important in insulation studies. In this research, testing on linear low density polythylene (LLDPE) with natural rubber (NR) and different weight concentration of biofiller are conducted under high voltage direct voltage (HVDC) by using needle and sphere types of electrode arrangements. Oil palm empty fruit bunch (OPEFB) and pineapple leaf fiber (PALF) are the biofillers used for the samples development. The LLDPE-NR samples consists of different weight percentages of biofiller which are 0%, 2.5%. 5.0%. 7.5% and 10% with 3mm thickness. The voltage has been increased until the breakdown occurs. Based on the results obtained, OPEFB and PALF with the highest weight percentages of 10% showed the highest damage voltages of 59.09kV and 59.36kV. It has been proven that both samples with the highest filler content have appropriate insulating properties. In conclusion, the addition of biofiber to LLDPE-NR has improved the breakdown properties compared to pure LLDPE.
Volume: 20
Issue: 3
Page: 1203-1209
Publish at: 2020-12-01

Reframing the effectiveness of feedback in improving teaching and learning achievement

10.11591/ijere.v9i4.20654
Anne Malar Selvaraj , Hazita Azman
Student feedback is established as an imperative learning and teaching technique, but feedback from students is less likely. The potential of feedback to boost learning outcomes refers to scholarly writing and is considered together as one of the most impressive methods for enhancing the success of students. In education, there is, nevertheless a lack of clarification about what feedback means and far less clarification on how one should interpret it. Feedback guides students to learn and supports them in order to achieve the aim of the lesson. The goal of this paper is to discuss teacherwritten reviews and obstacles to student feedback in order to recognise the usefulness of feedback in the education domain. Feedback from students illustrates the comprehensions, boundaries and features that knowledge should be compiled and employed to establish work or learning approach. The assessment study renders the appropriate feedback, and, in this manner, the students learn how to accomplish their learning goals. While feedback is not exclusively evaluated, these are the essential ingredients of making evaluation a mechanism for teachers’ and students’ future learning.
Volume: 9
Issue: 4
Page: 1055-1062
Publish at: 2020-12-01

Improved fuzzy c-means algorithm based on a novel mechanism for the formation of balanced clusters in WSNs

10.12928/telkomnika.v18i6.14716
Ali Abdul-hussian; Universiti Teknikal Malaysia Melaka Hassan , Wahidah Md; Universiti Teknikal Malaysia Melaka Shah , Abdul-hussien; University of Al-Zahraa for Women Hassan Habeb , Mohd Fairuz Iskandar; Universiti Teknikal Malaysia Melaka Othman
The clustering approach is considered as a vital method for many fields suchas machine learning, pattern recognition, image processing, information retrieval, data compression, computer graphics, and others.Similarly, it hasgreat significance in wireless sensor networks (WSNs) by organizing thesensor nodes into specific clusters. Consequently, saving energy and prolonging network lifetime, which is totally dependent on the sensor’s battery, that is considered asa major challenge in the WSNs. Fuzzyc-means (FCM) is one of classification algorithm, which is widely used in literature for this purpose in WSNs. However, according to the nature of random nodes deployment manner, on certain occasions, this situation forces this algorithm to produce unbalanced clusters, which adversely affects the lifetime of the network.To overcome this problem, a new clustering method called FCM-CMhas been proposed by improving the FCM algorithm to form balanced clustersfor random nodes deployment. The improvement is conductedby integrating the FCM with a centralized mechanism(CM).The proposed method will be evaluated based on four new parameters. Simulation result shows that our proposed algorithm is more superior to FCM by producing balanced clustersin addition to increasing the balancing of the intra-distances of the clusters, which leads to energy conservation and prolonging network lifespan.
Volume: 18
Issue: 6
Page: 2894-2902
Publish at: 2020-12-01

A survey on local binary pattern and gabor filter as texture descriptors of smart profiling systems

10.11591/ijeecs.v20.i3.pp1379-1387
Shihab Hamad Khaleefah , Salama A. Mostafa , Aida Mustapha , Noor Azah Samsudin , Mohammad Faidzul Nasrudin , Abdullah Baz
With the dramatic expansion of image information nowadays, image processing and computer visions are playing a significant role in terms of several applications such as image classification, image segmentation, pattern recognition, and image retrieval. One of the important features that have been used in many image applications is texture. The texture is the characteristic of a set of pixels that formed the image. Therefore, analyzing such texture would have a significant impact on segmenting the image or detecting important portions of such image. This paper aims to overview the feature extraction and description techniques depicted in the literature to characterize regions for images. In particular, two of popular descriptors will be examined including local binary pattern (LBP) and gabor filter. The key characteristic behind such investigation lies in how the features of an image would contribute toward the process of recognition and image classification. In this regard, an extensive discussion is provided on both LBP and Gabor descriptors along with the efforts that have been intended to combine them. The reason behind investigating these descriptors is that they are considered the most common local and global descriptors used in the literature. The overall aim of this survey is to show current trends on using, modifying and adapting these descriptors in the domain of image processing.
Volume: 20
Issue: 3
Page: 1379-1387
Publish at: 2020-12-01

Mitigation of non-linear four-wave mixing phenomenon in a fully optical communication system

10.12928/telkomnika.v18i6.16136
Petr; University of Žilina Ivaniga , Tomáš; University of Technology Košice Ivaniga
This paper aims to point out the nonlinear phenomenon occurring in coarse/dense wavelength division multiplex (C/D-WDM) systems. This phenomenon has to betaken into account during the design of the optical network itself, as wavelengthsin the optical fiber are constantly densified. The paper points out the emergence of the non-linear four-wave mixing (FWM) phenomenonand how it relates to the dispersion in the optical fiber together with the transmit power. The output of the paper is a proposed design of the system that points to the improvement of the bit error rate (BER) with a suitable choice of dispersion and suitable transmission power.
Volume: 18
Issue: 6
Page: 2878-2885
Publish at: 2020-12-01

Modelling of solar micro gas turbine for parabolic dish based controller application

10.12928/telkomnika.v18i6.16676
Syariffah; Universiti Teknikal Malaysia Melaka Othman , Mohd Ruddin; Universiti Teknikal Malaysia Melaka Ab. Ghani , Zanariah; Universiti Teknikal Malaysia Melaka Jano , Tole; Universitas Ahmad Dahlan Sutikno
Dish-Stirling unit and photovoltaic panels are the premier technologies available to generate off-grid solar energy. The major issue for both systems is in terms of producing output power. Air-Brayton cycle was utilized asan engine by converting the thermal energy to electricity. Micro gas turbine (MGT) has been recognized as one of the viable alternatives compared to Stirling engines, where it represents a state-of-art parabolic dish engine specifically in turbine gas technology. Hence, the microgas turbine is a technology that is capable of controlling low carbon while providing electricity in off-grid regions. MGT uses any gas as its input like natural gas, bio gas and others. Micro gas turbine has advantages for its high expansion ratio and less moving components. Compared to competing for diesel generators, the electricity costs from hybrid solar units were reduced between 10% and 43%, where  as specific CO2 emissions reduced by 20-35%. MGT provides advantages over photovoltaic systems such as the inherent ability to hybridize the systems with hydrocarbon fuels to produce electricity around the clock, and the ability to operate more effectively in very hot climates with photovoltaic performance degradation over the life time of the  system. Hybrid solar micro gas-turbines are cost-effective, eco-friendly and pollution free as they can work by burning any gas like natural gas,landfill gasa and others.This paper presented the controls contained in the MGT-dish system consisted of temperature control, fuel flow control, speed and acceleration control. Aconceptual design of the 25kW MGT-dish system was also covered.
Volume: 18
Issue: 6
Page: 3184-3190
Publish at: 2020-12-01

Sliding mode performance control applied to a DFIG system for a wind energy production

10.11591/ijece.v10i6.pp6139-6152
Mansouri FatimaZohra , Bendjebbar Mokhtar , Mazari Benyounes
This project presents a strategy of field control then sliding mode control put in to the conversion process of wind energy containing an asynchronous generator with double fed (DFAG; DFIG). A model was developed for each component of the wind turbine (turbine, DFAG and cascade rectifier-inverter). MPPT device must be introduced in order to obtain maximum energy efficiency so that PI-MPPT method is made. The objective is to apply this command to control independently the active and reactive powers generated by the asynchronous generator uncoupled by orientation from the flow. The results of digital simulations obtained show the improvement of the performances of the sliding control compared to the field control, also it has provided information on the commands available techniques as reference tracking and robustness.
Volume: 10
Issue: 6
Page: 6139-6152
Publish at: 2020-12-01

Fuzzy logic control of hybrid systems including renewable energy in microgrids

10.11591/ijece.v10i6.pp5559-5569
Omar Feddaoui , Riad Toufouti , Labed Jamel , Salima Meziane
With a growing demand for more energy from subscribers, a traditional electric grid is unable to meet new challenges, in the remote areas remains the extension of the conventional electric network very hard to do make prohibitively expensive. Therefore, a new advanced generation of traditional electrical is inevitable and indispensable to move toward an efficient, economical, green, clean and self-correcting power system. The most well-known term used to define this next generation power system is Micro Grid (MG) based on renewable energy sources (RES). Since, the energy produced by RES are not constant at all times, a wide range of energy control techniques must be involved to provide a reliable power to consumers. To solve this problem in this paper we present a Fuzzy Logic Control of isolated Hybrid Systems (HRES) Including Renewable Energy in Micro-Grids to maintain a stability in voltage and frequency output especially in the standalone application. The considered HRES combine a wind turbine (WT) and photovoltaic (PV) panels as primary energy sources and an energy storage system (ESS) based on battery as a backup solution. Simulation results obtained from MATLAB/Simulink environment demonstrate the effectiveness of the proposed algorithm in decreasing the electricity bill of customer.
Volume: 10
Issue: 6
Page: 5559-5569
Publish at: 2020-12-01

Motion artifacts reduction in cardiac pulse signal acquired from video imaging

10.11591/ijece.v10i6.pp5687-5693
Murthad Al-Yoonus , Mustafa H. Alhabib , Mustafa Zuhaer Nayef Al-Dabagh , M. F. L. Abdullah
This study examines the possibility of remotely measuring the cardiac pulse activity of a patient, which could be an alternative technique to the classical method. This type of measurement is non-invasive. However, several limitations may deteriorate the accuracy of the results, including changes in ambient illumination, motion artifacts (MA) and other interferences that may occur through video recording. The paper in hand presents a new approach as a remedy for the aforementioned problem in cardiac pulse signals extracted from facial video recordings. Partitioning provides the basis for the presented MA reduction method; the acquired signals are partitioned into two sets for each second and every partition is shifted to the mean level and then all the partitions are recombined again into one signal, which is followed by low-pass filtering for enhancement. The proposed compared with ordinary pulse oximetry Photoplethysmographic (PPG) method. The resulted correlation coefficient was found (0.957) when calculated between the results of the proposed method and the ordinary one. Experiments were implemented using a common camera by creating a dataset from 11 subjects. The ease of implementation of this method with a simple that can be used to monitor the cardiac pulse rates in both home and the clinical environments.
Volume: 10
Issue: 6
Page: 5687-5693
Publish at: 2020-12-01

Science-related aspirations of career based on learning content in upper secondary level

10.11591/ijere.v9i4.20650
Mohd Razimi Husin , Hishamuddin Bin Ahmad , Muhammad Bazlan Bin Mustafa , Ismail Yusuf Panessai , Ramlan Ramlan
This study used qualitative approach which involves interviews that are analyze using Nvivo software. Qualitative approach which uses phenomenological design to reflect on the experience of the former students towards their experience and learning contents of secondary school upper level science core subject which impacted their career aspirations today. Twelve experience workers were selected through purposeful sampling. The results show that most respondent just got C for their Science Subject in Malaysian Certificate of Education (MCE). The certain techniques including the use of the learning aids and room were very effective; while contents of fluid and organs were much related to works. This study has revealed the effective techniques of learning experiences that beneficial to all educators.
Volume: 9
Issue: 4
Page: 920-925
Publish at: 2020-12-01

Predictions on wheat crop yielding through fuzzy set theory and optimization techniques

10.12928/telkomnika.v18i6.15870
Julio Barón; Universidad Distrital Francisco José de Caldas Velandia , Norbey Danilo Muñoz; Universidad Distrital Francisco José de Caldas Cañón , Brayan Leonardo Sierra; Universidad Distrital Francisco José de Caldas Forero
Agricultural field’s production is commonly measured through the performance of the crops in terms of sow amount, climatology, and the type of crop, among other. Therefore, prediction on the performance of the crops canaid cultivators to make better informed decisions and help the agricultural field. This research work presents a prediction on wheat crop using the fuzzy set theory and the use of optimization techniques, in both; traditional methods and evolutionary meta-heuristics. The performance prediction in this research has its core on the following parameters: biomass, solar radiation, rainfall, and infield’s water extractions. Besides, the needed standards and the efficiency index (EFI) used come from already developed models; such standards include: the root-mean-square error (RMSE), the standard deviation, and the precision percentage. The applicationof a genetic algorithm on a Takagi-Sugeno system requires and highly precise prediction on wheat cropping;being, 0.005216 the error estimation, and 99,928 the performance percentage.
Volume: 18
Issue: 6
Page: 3011-3018
Publish at: 2020-12-01

A novel two-polynomial criteria for higher-order systems stability boundaries detection and control

10.12928/telkomnika.v18i6.16256
N.; Swinburne University Mir-Nasiri , Md. Hazrat; Nazarbayev University Ali
There are many methods for identifying the stability of complex dynamic systems. Routh and Hurwitz’s criterion is one of the earliest and commonly used analytical tools analysing the stability of dynamic systems. However, it requires tedious and lengthy derivations of all components of the Routh array to solve the stability problem. Therefore, it is not a simple method to define analytically, stability boundaries for the coefficients of the system characteristic equation.The proposed brand-new criterion is an effective alternaztive technique in identifying stabilityhigher-order linear time-invariant dynamic system that binds the coefficients of the system characteristic polynomial at the stability boundaries by means of an additional single constantk. It defines the necessary and sufficient conditions for the absolute stability of higher-order dynamic systems. It also allows the analysing of the system’s precise marginal stabilityor marginal instability condition when the roots are relocated on imaginary jω-axis of s-plane. The criterion proposed bythe authors, in contrast to Routh criteria, simplifies the identification of maximum and minimum stability limits for any coefficient of the higher-order characteristic equation significantly. The derived in the paperstability boundary formulas for the polynomial coefficients are successfully used for the proportional integral derivative (PID) controller with single or multiple gains selections in closed-loop control system.
Volume: 18
Issue: 6
Page: 3164-3172
Publish at: 2020-12-01

Towards better performance: phase congruency based face recognition

10.12928/telkomnika.v18i6.17300
Muthana H.; Al-Mustansiriyah University Hamd , Rabab A.; Al-Mustansiriyah University Rasool
Phase congruency is an edge detector and measurement of the significant feature in the image. It is a robust method against contrast and illumination variation. In this paper, two novel techniques are introduced for developing alow-cost human identification system based on face recognition. Firstly, the valuable phase congruency features, the gradient-edges and their associate dangles are utilized separately for classifying 130 subjects taken from three face databases with the motivation of eliminating the feature extraction phase. By doing this, the complexity can be significantly reduced. Secondly, the training process is modified when a new technique, called averaging-vectors is developed to accelerate the training process and minimizes the matching time to the lowest value. However, for more comparison and accurate evaluation,three competitive classifiers:  Euclidean distance (ED),cosine distance (CD), and Manhattan distance (MD) are considered in this work. The system performance is very competitive and acceptable, where the experimental  results show promising recognition rates with a reasonable matching time.
Volume: 18
Issue: 6
Page: 3041-3049
Publish at: 2020-12-01

Speech encryption by multiple chaotic map with fast fourier transform

10.11591/ijece.v10i6.pp5658-5664
Yahia Alemami , Mohamad Afendee Mohamed , Saleh Atiewi , Mustafa Mamat
There are various ways of social communication including writing (WhatsApp, Messenger, Facebook, Twitter, Skype, etc), calling (mobile phone) and voice recording (record your voice and then send it to the other party), but there are ways to eavesdropping the calls and voice messages, One way to solve this problem is via cryptographic approach. Chaos cryptography build on top of nonlinear dynamics chaotic system has gained some footstep in data security. It provides an alternative to conventional cryptography built on top of mathematical structures. This research focuses on the protection of speech recording by encrypting it with multiple encryption algorithms, including chaotic maps (Logistic Map and Sine Maps).
Volume: 10
Issue: 6
Page: 5658-5664
Publish at: 2020-12-01

Adopted topic modeling for business process and software component conformity checking

10.12928/telkomnika.v18i6.13381
Adhatus Solichah; Institut Teknologi Sepuluh Nopember Ahmadiyah , Riyanarto; Institut Teknologi Sepuluh Nopember Sarno , Fony; Institut Teknologi Sepuluh Nopember Revindasari
Business processes and software components, especially class diagrams, have a firm connection. Considering software components support the business process in providing an excellent product and service. Besides, business process changes affect on software component design. One of them usually appears on the label or name of the software component or business process. Sometimes, a related business process and software component appears in the different label but the same meaning rather than using the same label. This situation is problematic when there are many changes to be made, in which the software component's modifying process becomes quite long. Therefore, the software maintainers should obtain an efficient procedure to shorten the modifying process. One solution is by using conformity checking, which helps the software maintainers know which software component is related to a specific business process. This paper compared two leading topic modeling techniques, namely probabilistic latent semantic analysis (PLSA) and latent Dirichlet allocation (LDA), to determine which one has a better performancefor process traceability.
Volume: 18
Issue: 6
Page: 2939-2947
Publish at: 2020-12-01
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