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29,922 Article Results

Evaluation of options portfolios for exchange rate hedges

10.11591/ijeecs.v21.i1.pp406-411
Miguel Jiménez-Gómez , Natalia Acevedo-Prins , Miguel Rojas-López
In this paper evaluate six exchange rate hedging strategies with financial options from the OTC market in Colombia. Three hedging strategies for importers and three for exporters were raised. The coverage for importers was carried out with the traditional strategy of long call, bull call spread and bull put spread, the last two correspond to options portfolios. the coverage for importers was carried out with the traditional strategy of long put, bear call spread and bear put spread, the last two correspond to options portfolios. to determine the best hedging strategy, the currency price was modeled with a Wiener process and the VaR for the six covered scenarios was calculated and compared with the VaR of the uncovered scenario. The results shown by the six hedging strategies manage to mitigate the exchange risk, but the most efficient strategies are the traditional ones for both importers and exporters.
Volume: 21
Issue: 1
Page: 406-411
Publish at: 2021-01-01

Security schemes based on conditional privacy-preserving vehicular ad hoc networks

10.11591/ijeecs.v21.i1.pp479-488
Mahmood A. Al-shareeda , Mohammed Anbar , Murtadha A. Alazzawi , Selvakumar Manickam , Iznan H. Hasbullah
Recently, vehicular ad hoc networks (VANETs) have been garnering significant inter-est from the people involved in transportation field. Nowadays automotive manufactur-ers have already supplying vehicles with multitude of road sensors that provides many useful characteristics. VANET communication not only offers the drivers and passen-gers with the various safety related services but also provides a wide range of valuable applications. However, the inherent openness of the wireless communication medium used by VANETs exposes vehicles to various security and privacy issues. Researchers have proposed many security schemes to solve the issues mentioned above for the widespread deployment of VANETs. However, these schemes failed to fulfill all as-pects of security and privacy requirements. Besides, these schemes have not provided the performance parameters such as computation and communication costs. The pri-mary emphasis of this paper is on the taxonomy of security schemes based conditional privacy-preserving with respect to strengths and limitations. Besides, a comparison be-tween these schemes related to the model of security and privacy requirements, attacks, and performance parameters is provided. Finally, this paper critically reviews the re-lated works by taking into consideration the design and development of all VANETs security and privacy schemes, this paper could serve as a guide and reference.
Volume: 21
Issue: 1
Page: 479-488
Publish at: 2021-01-01

3D face creation via 2D images within blender virtual environment

10.11591/ijeecs.v21.i1.pp457-464
Ali Salim Rasheed , Rasool Hasan Finjan , Ahmed Abdulsahib Hashim , Mustafa Murtdha Al-Saeedi
Animation and virtual reality movie-making technologies are still witnessing significant progress to this day. Building and stimulating virtual characters inside these applications is a goal. Build a 3D face via using some special tools inside the virtual world is the most important part of identifying a 3D animation. Keen Tools Face Builder add-on for Blender. Interested in creating a 3D face of a famous figure, artist or the general public by adopting several 2D images added to the virtual blinder software environment. The main problem facing these tools is that they deal with high-resolution and sharpness pictures because some images that contain blurring, the result is to build a 3D face model that contains design distortions and non- clearly. in this proposed paper, build a data set for 2D pictures of a specific character (actor), at a resolution of 1920 x 1080 pixels. These images were caught by the camera, different in sharpness and blurring (four types of blurry). Using the “Laplacian Filter algorithm” and OpenCV library with Python language, to isolate blurry from sharpness 2D images. Sharpness images used to build a 3D face model that gave real and similar results to the character in the pictures. 
Volume: 21
Issue: 1
Page: 457-464
Publish at: 2021-01-01

Stamps extraction using local adaptive k- means and ISODATA algorithms

10.11591/ijeecs.v21.i1.pp137-145
Maha A. Rajab , Loay E. George
One of the main difficulties facing the certified documents documentary archiving system is checking the stamps system, but, that stamps may be contains complex background and surrounded by unwanted data. Therefore, the main objective of this paper is to isolate background and to remove noise that may be surrounded stamp. Our proposed method comprises of four phases, firstly, we apply k-means algorithm for clustering stamp image into a number of clusters and merged them using ISODATA algorithm. Secondly, we compute mean and standard deviation for each remaining cluster to isolate background cluster from stamp cluster. Thirdly, a region growing algorithm is applied to segment the image and then choosing the connected region to produce a binary mask for the stamp area. Finally, the binary mask is combined with the original image to extract the stamp regions. The results indicate that the number of clusters can be determined dynamically and the largest cluster that has minimum standard deviation (i.e., always the largest cluster is the background cluster). Also, show that the binary mask can be established from more than one segment to cover are all stamp’s disconnected pieces and it can be useful to remove the noise appear with stamp region.
Volume: 21
Issue: 1
Page: 137-145
Publish at: 2021-01-01

Optimal planning of RDGs in electrical distribution networks using hybrid SAPSO algorithm

10.11591/ijece.v10i6.pp6153-6163
Mohammed Hamouda Ali , Mohammed Mehanna , Elsaied Othman
The impact of the renewable distributed generations (RDGs), such as photovoltaic (PV) and wind turbine (WT) systems can be positive or negative on the system, based on the location and size of the DG. So, the correct location and size of DG in the distribution network remain an obstacle to achieving their full possible benefits. Therefore, the future distribution networks with the high penetration of DG power must be planned and operated to improve their efficiency. Thus, this paper presents a new methodology for integrated of renewable energy-based DG units with electrical distribution network. Since the main objective of the proposed methodology is to reduce the power losses and improve the voltage profile of the radial distribution system (RDS). In this regard, the optimization problem was formulated using loss sensitivity factor (LSF), simulated annealing (SA), particle swarm optimization (PSO) and a combination of loss sensitivity index (LSI) with SA & PSO (LSISA, LSIPSO) respectively. This paper contributes a new methodology SAPSO, which prevents the defects of SA & PSO. Optimal placement and sizing of renewable energy-based DG tested on 33-bus system. The results demonstrate the reliability and robustness of the proposed SAPSO algorithm to find the near-optimal position and size of the DG units to mitigate the power losses and improve the radial distribution system's voltage profile.
Volume: 10
Issue: 6
Page: 6153-6163
Publish at: 2020-12-01

A new multilevel inverter with reduced switch count for renewable power applications

10.11591/ijpeds.v11.i4.pp2145-2153
Seong-Cheol Kim , S. Narasimha , Surender Reddy Salkuti
This paper proposes a new technique for a voltage source multilevel inverter (MLI) with reduced switch count, and it creates a smoother sinusoidal output waveform with reduced total harmonic distortion (THD). Therefore, the proposed technique identifies a better position in the list of multilevel converters used for power quality conditioners. Semiconducting devices are added to it if the number of levels increases. In this work, the topology of MLI with reduced number of switches is presented. A new MLI is proposed with lower number of switches and sources in order to achieve higher level. The proposed topology is framed out with the combination of three half bridge and a single H-bridge configuration. Detailed simulation results for 15-level inverter of single and three phase inverters are presented in this paper. Three phase 15-level inverter is developed by employing three isolated different renewable sources and 21 switches.
Volume: 11
Issue: 4
Page: 2145-2153
Publish at: 2020-12-01

New adaptive hysteresis band width control for direct torque control of induction machine drives

10.11591/ijpeds.v11.i4.pp1908-1917
Arkan A. Kadum
This paper presents a new adaptive hysteresis band control approach used in direct torque control (DTC) of the induction motor (IM) drives with the switching tables for the generation of PWM signals. Constant Hysteresis Direct torque control (CHB-DTC) method used the torque and stator flux errors to generate the stator voltage reference and frequency vectors for controlling the three-phase induction motor. The CHB-DTC gives better torque transient performance but it has large steady state ripples. To reduce torque and stator current ripples in CHB-DTC controlled induction motor drives a new adaptive hysteresis band control (AHB) approach is proposed, where the hysteresis band is adapted in real time with the stator flux and torque errors variation, instead of fixed bandwidth. Both classical CHB-DTC method and the proposed adaptive hysteresis band DTC (AHB-DTC) fed three induction motor have been simulated using Matlab/Simulink. The simulation results at different operating conditions over a wide speed range demonstrate the validity, effectiveness, and feasibility of the proposed scheme. The measurements showed that torque ripples were significantly decrease with the new AHB-DTC technique and better speed response in step up or down compared to the CHB-DTC.
Volume: 11
Issue: 4
Page: 1908-1917
Publish at: 2020-12-01

An approach for a multi-stage under-frequency based load shedding scheme for a power system network

10.11591/ijece.v10i6.pp6071-6100
Mkhululi Elvis Siyanda Mnguni , Yohan Darcy Mfoumboulou
The integration of load shedding schemes with mainstream protection in power system networks is vital. The traditional power system network incorporates different protection schemes to protect its components. Once the power network reaches its maximum limits, and the load demand continue to increase the whole system will experience power system instability. The system frequency usually drops due to the loss of substantial generation creating imbalance. The best method to recover the system from instability is by introducing an under-frequency load shedding (UFLS) scheme in parallel with the protection schemes. This paper proposed a new UFLS scheme used in power systems and industry to maintain stability. Three case studies were implemented in this paper. Multi-stage decision-making algorithms load shedding in the environment of the DIgSILENT power factory platform is developed. The proposed algorithm speeds-up the operation of the UFLS scheme. The load shedding algorithm of the proposed scheme is implemented as a systematic process to achieve stability of the power network which is exposed to different operating conditions. The flexibility of the proposed scheme is validated with the modified IEEE 39-bus New England model. The application of the proposed novel UFLS schemes will contribute further to the development of new types of engineers.
Volume: 10
Issue: 6
Page: 6071-6100
Publish at: 2020-12-01

Performance comparison of different control strategies for the regulation of DC-DC negative output super-lift luo-converter

10.11591/ijece.v10i6.pp5785-5792
Hassan Jassim Motlak , Ahmed S. Rahi
In last years, dc-dc converters solve the most issues in the industrial application in the area of power electronics, especially renewable energy, military applications and affiliated engineering developments. They are used to convert the DC input that unregulated to regulated output perhaps larger or smaller than input according to the type of converters. This paper presents three primary control method used for negative output Super lift Luo DC-DC converter. These methods include a Voltage mode control (VMC), Current mode control (CMC), and Sliding mode control (SMC). The goal of this article is to study and selected an appropriate and superior control scheme for negative DC-DC converters. The simulation results show the effectiveness of Sliding mode control for enhancing the performance of the negative dc-dc converter. Also, this method can keep the output voltage constant under load conditions. simulation results obtained by the MATLAB/Simulink environment.
Volume: 10
Issue: 6
Page: 5785-5792
Publish at: 2020-12-01

The relationship between preschool teachers’ self-efficacy beliefs and their teaching attitudes

10.11591/ijere.v9i4.20670
Kamil Arif Kırkıç , Fatma Çetinkaya
This study examined the relationship between preschool teachers’ selfefficacy beliefs and their teaching attitudes. In the study, it was considered whether preschool teachers’ self-efficacy beliefs and their teaching attitudes change in terms of certain variables. The research was carried out using a correlational survey model. The target population of the study is the preschool teachers working in Küçükçekmece district, İstanbul Province, in the 2017-2018 academic year. The working group consists of 264 preschool teachers working at the schools in said district. The following assessment instruments were used in the research: “Personal Information Form,” “Preschool Teachers’ Self-efficacy Beliefs Scale,” to identify preschool teachers’ self-efficacy beliefs and ‘Preschool Teachers’ Teaching Attitudes Scale’ to determine the teachers’ attitudes. The obtained data were analyzed using Pearson multiplication moment correlation analysis, and Regression analysis was performed to determine the level of self-efficacy beliefs of preschool teachers affecting teaching attitudes. Preschool teachers were found to have full self-efficacy beliefs in the teaching-learning process, communication skills, planning, and regulation of learning environments and classroom management, and firm self-efficacy beliefs in family participation. Teachers’ attitudes of preschool teachers were found to be democratic at the highest level, followed by autocratic and laissez-faire at the lowest level. As a result of the regression analysis made to determine the level of the effect of self-efficacy beliefs of preschool teachers on their teaching attitudes, the learning and teaching process positively predicts democratic teaching attitudes and negatively predicts laissez-faire attitudes.
Volume: 9
Issue: 4
Page: 807-815
Publish at: 2020-12-01

Performance evaluation of PI controller for positive output Luo converter

10.11591/ijpeds.v11.i4.pp1816-1825
Muhammed Abduljaleel Ibrahim
The aim of this work is to design and analyze a Proportional Integral (PI) controller for Positive Output Luo Converter applications. Positive Output Luo Converter is a developed DC-DC converter. It is respected as a right choice for most industrial application where the rate of the output load voltage must be varying between the low and high values of the input value of voltage, output voltage rise and fall is smaller. This converter involve Power electronics switches (Diodes and MOSFET) since these elements are non-linear. The detailed model includes high-frequency switching that is introducing discontinuities into the model. PI controller coefficients (kp, ki) are calculated by particle swarm optimization (PSO) to provide optimal PI as hybrid PI by PSO controller with simple design procedure .Transient and steady state responses requirement of the system are considered in designing the proposed PI controller. The consequences show that the time of performing characteristics of PSO-PI controller established on integral squared error (ISE) performance index has the best time performing characteristics, line disturbance, load disturbance and set point variation.
Volume: 11
Issue: 4
Page: 1816-1825
Publish at: 2020-12-01

Compressive spectrum sensing using two-stage scheme for cognitive radio networks

10.11591/ijece.v10i6.pp5899-5908
Montadar Abas Taher , Mohammad Z. Ahmed , Emad Hmood Salman
The modern applications of communications that use wideband signals suffer the lacking since the resources of this kind of signals are limited especially for fifth generation (5G). The Compressive Spectrum Sensing (COMPSS) techniques address such issues to reuse the detected signals in the networks and applications of 5G. However, the raw techniques of COMPSS have low compression ratio and high computational complexity rather than high level of noise variance. In this paper, a hybrid COMPSS scheme has been developed for both non-cooperative and cooperative cognitive radio networks. The proposed scheme compiles on discrete wavelet transform – single resolution (DWT-SR) cascaded with discrete cosine transform (DCT). The first is constructed according to the pyramid algorithm to achieve 50% while the second performed 30% compression ratios. The simulation and analytic results reveal the significant detection performance of the proposed technique is better than that of the raw COMPSS techniques.
Volume: 10
Issue: 6
Page: 5899-5908
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

An improved zero-voltage zero-current transition boost converter employing L-C-S resonant network

10.11591/ijpeds.v11.i4.pp1844-1856
Anandh N , Akhilesh Sharma , Julius Fusic S , Ramesh H
An improved zero-voltage zero-current transition boost converter (IZVZCTBC) is introduced. This converter is basically a fourth-order DC-DC converter wherein a L-C-S (Inductor–Capacitor–Switch) resonant circuit is embedded for soft-switching. L-C-S tank network is the modified version of conventional ZVZCT switch cell. The main feature of L-C-S tank circuit is to enhance the performance of zero-voltage zero-current transition boost converter in terms of eliminating the high current stress, decreasing the switching losses and increasing the efficiency of converter. This converter exhibits both zero-voltage turn on and zero-current turn off switching characteristics based on the gating signals applied to switches. The principle of operation and time domain expressions of IZVZCT boost converter with L-C-S cell are presented. For the closed loop operation, digital controller is designed and the performance of the controller has been validated through simulation for different line and load variations. The mathematical and theoretical analysis is verified accurately by a 12-24 V, 30 W converter through PSIM simulation software and the results ensures that overall efficiency of the converter has improved to 97% along with elimination of current stress.
Volume: 11
Issue: 4
Page: 1844-1856
Publish at: 2020-12-01

A real-time system for vehicle detection with shadow removal and vehicle classification based on vehicle features at urban roads

10.11591/ijpeds.v11.i4.pp2091-2098
Issan Atouf , Wahban Yahya Al Okaishi , Abdelmoghit Zaaran , Ibtissam Slimani , Mohamed Benrabh
Monitoring traffic in urban areas is an important task for intelligent transport applications to alleviate the traffic problems like traffic jams and long trip times. The traffic flow in urban areas is more complicated than the traffic flow in highway, due to the slow movement of vehicles and crowded traffic flows in urban areas. In this paper, a vehicle detection and classification system at intersections is proposed. The system consists of three main phases: vehicle detection, vehicle tracking and vehicle classification. In the vehicle detection, the background subtraction is utilized to detect the moving vehicles by employing mixture of Gaussians (MoGs) algorithm, and then the removal shadow algorithm is developed to improve the detection phase and eliminate the undesired detected region (shadows). After the vehicle detection phase, the vehicles are tracked until they reach the classification line. Then the vehicle dimensions are utilized to classify the vehicles into three classes (cars, bikes, and trucks). In this system, there are three counters; one counter for each class. When the vehicle is classified to a specific class, the class counter is incremented by one. The counting results can be used to estimate the traffic density at intersections, and adjust the timing of traffic light for the next light cycle. The system is applied to videos obtained by stationary cameras. The results obtained demonstrate the robustness and accuracy of the proposed system.
Volume: 11
Issue: 4
Page: 2091-2098
Publish at: 2020-12-01
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