Search results for: power distance

Authors: Jareeluk Ratanaphan

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The purposed of this research were; 1. To survey the teacher’s needs on knowledge about special education management for special needs student 2. Development of distance training packages for teacher on special education management for special needs student 3. to study the effects of using the packages on trainee’s achievement 4. to study the effects of using the packages on trainee’s opinion on the distance training packages. The design of the experiment was research and development. The research sample for survey were 86 teachers, and 22 teachers for study the effects of using the packages on achievement and opinion. The research instrument comprised: 1) training packages on special education management for special needs student 2) achievement test 3) questionnaire. Mean, percentage, standard deviation, t-test and content analysis were used for data analysis. The findings of the research were as follows: 1. The teacher’s needs on knowledge about teaching for a learner with learning disability, mental retardation, autism, physical and health impairment and research in special education. 2. The package composed of special education management for special needs student document and manual of distance training packages. The document consisted by the name of packages, the explanation for the educator, content’s structure, concept, objectives, content and activities. Manual of distance training packages consisted by the explanation about a document, objectives, explanation about using the package, training schedule, and evaluation. The efficiency of packages was established at 79.50/81.35. 3. The results of using the packages were the posttest average scores of trainee’s achievement were higher than the pretest. 4. The trainee’s opinion on the package was at the highest level.

Keywords: distance training package, teacher, learner with special needs

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Authors: Alireza Shayegan, Morteza Amirabadi

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The y tool was developed to quantitatively compare dose distributions, either measured or calculated. Before computing ɣ, the dose and distance scales of the two distributions, referred to as evaluated and reference, are re-normalized by dose and distance criteria, respectively. The re-normalization allows the dose distribution comparison to be conducted simultaneously along dose and distance axes. Several two-dimensional images were acquired using a Scanning Liquid Ionization Chamber EPID and Extended Dose Range (EDR2) films for regular and irregular radiation fields. The raw images were then converted into two-dimensional dose maps. Transitional and rotational manipulations were performed for images using Matlab software. As evaluated dose distribution maps, they were then compared with the corresponding original dose maps as the reference dose maps.

Keywords: energetic electron, gamma function, penumbra, Matlab software

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Authors: Ahmed Elsebaay, Maged A. Abu Adma, Mahmoud Ramadan

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This study presents a technique clarifying the effect of ambient air temperature and loads power factor changing from standard values on electric generator power rating. The study introduces an optimized technique for selecting the correct electric generator power rating for certain application and operating site ambient temperature. The de-rating factors due to the previous effects will be calculated to be applied on a generator to select its power rating accurately to avoid unsafe operation and save its lifetime. The information in this paper provides a simple, accurate, and general method for synchronous generator selection and eliminates common errors.

Keywords: ambient temperature, de-rating factor, electric generator, power factor

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Authors: Leila Goosen, Dalize van Heerden

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The performance outcomes of first year Computer Science and Information Technology students across the world are of great concern, whether they are being taught in a face-to-face environment or via distance education. In the face-to-face environment, it is, however, somewhat easier to teach and support students than it is in a distance education environment. The face-to-face academic can more easily gauge the level of understanding and participation of students and implement interventions to address issues, which may arise. With the inroads that Web 2.0 and Web 3.0 technologies are making, the world of online teaching and learning are rapidly expanding, bringing about technologies, which allows for similar interactions between online academics and their students as available to their face-to-face counter parts. At the University of South Africa (UNISA), the Learning Management System (LMS) is called myUNISA and it is deployed on a SAKAI platform. In this paper, we will take a look at some of the myUNISA technologies implemented in the teaching of a first year programming course, how they are implemented and, in some cases, we will indicate how this affects the performance outcomes of students.

Keywords: computer science, Distance Education Technologies, Learning Management System, face-to-face environment

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Authors: Fatima Khurshid, Noor Ul Ain, Syed Abdul Rehman Kashif, Zainab Riaz, Abdullah Usman Khan, Muhammad Imran

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As the world is moving towards extra-high voltage (EHV) and ultra-high voltage (UHV) power systems, the performance requirements of power transformers are becoming crucial to the system reliability and security. With the transformers being an essential component of a power system, low health index of transformers poses greater risks for safe and reliable operation. Therefore, to meet the rising demands of the power system and transformer performance, researchers are being prompted to provide solutions for enhanced thermal and electrical properties of transformers. This paper proposes an approach to improve the health index of a transformer by using nano-technology in conjunction with bio-degradable oils. Vegetable oils can serve as potential dielectric fluid alternatives to the conventional mineral oils, owing to their numerous inherent benefits; namely, higher fire and flashpoints, and being environment-friendly in nature. Moreover, the addition of nanoparticles in the dielectric fluid further serves to improve the dielectric strength of the insulation medium. In this research, using the finite element method (FEM) in COMSOL Multiphysics environment, and a 2D space dimension, three different oil samples have been modelled, and the electric field distribution is computed for each sample at various electric potentials, i.e., 90 kV, 100 kV, 150 kV, and 200 kV. Furthermore, each sample has been modified with the addition of nanoparticles of different radii (50 nm and 100 nm) and at different interparticle distance (5 mm and 10 mm), considering an instant of time. The nanoparticles used are non-conductive and have been modelled as alumina (Al₂O₃). The geometry has been modelled according to IEC standard 60897, with a standard electrode gap distance of 25 mm. For an input supply voltage of 100 kV, the maximum electric field stresses obtained for the samples of synthetic vegetable oil, olive oil, and mineral oil are 5.08 ×10⁶ V/m, 5.11×10⁶ V/m and 5.62×10⁶ V/m, respectively. It is observed that for the unmodified samples, vegetable oils have a greater dielectric strength as compared to the conventionally used mineral oils because of their higher flash points and higher values of relative permittivity. Also, for the modified samples, the addition of nanoparticles inhibits the streamer propagation inside the dielectric medium and hence, serves to improve the dielectric properties of the medium.

Keywords: dielectric strength, finite element method, health index, nanotechnology, streamer propagation

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Authors: Mohammad Mahdi Kioumarsi

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In this paper, using the response surface method (RSM), tornado diagram method and non-linear finite element analysis, the effect of four parameters on residual bending capacity of a corroded RC beam was investigated. The parameters considered are amount of localised cross section reduction, ratio of pit distance on adjacent bars to rebar distance, concrete compressive strength, and rebar tensile strength. The focus is on the influence on the bending ultimate limit state. Based on the obtained results, the effects of the ratio of pit distance to rebar distance (Lp⁄Lr) and the ratio of the localised cross section reduction to the original area of the rebar (Apit⁄A0) were found significant. The interference of localised corrosion on adjacent reinforcement bars reduces the bending capacity of under-reinforced concrete beam. Using the sensitivity analysis could lead to recognize uncertainty parameters, which have the most influences on the performance of the structure.

Keywords: localised corrosion, concrete beam, sensitivity analyses, ultimate capacity

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Authors: M. F. Miah, K. M. A. Zinnah, M. J. Raihan, H. Ali, M. N. Naser

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As genetic diversity is most important for existing, breeding and production of any fish; this study was undertaken for investigating genetic diversity of freshwater mud eel, Monopterus cuchia at population level where three ecological populations such as flooded area of Sylhet (P1), open water of Moulvibazar (P2) and open water of Sunamganj (P3) districts of Bangladesh were considered. Four arbitrary RAPD primers (OPB-12, C0-4, B-03 and OPB-08) were screened and RAPD banding patterns were analyzed among the populations considering 15 individuals of each population. In total 174, 138 and 149 bands were detected in the populations of P1, P2 and P3 respectively; however, each primer revealed less number of bands in each population. 100% polymorphic loci were recorded in P2 and P3 whereas only one monomorphic locus was observed in P1, recorded 97.5% polymorphism. Different genetic parameters such as inter-individual pairwise similarity, genetic distance, Nei genetic similarity, linkage distances, cluster analysis and allelic information, etc. were considered for measuring genetic diversity. The average inter-individual pairwise similarity was recorded 2.98, 1.47 and 1.35 in P1, P2 and P3 respectively. Considering genetic distance analysis, the highest distance 1 was recorded in P2 and P3 and the lowest genetic distance 0.444 was found in P2. The average Nei genetic similarity was observed 0.19, 0.16 and 0.13 in P1, P2 and P3, respectively; however, the average linkage distance was recorded 24.92, 17.14 and 15.28 in P1, P3 and P2 respectively. Based on linkage distance, genetic clusters were generated in three populations where 6 clades and 7 clusters were found in P1, 3 clades and 5 clusters were observed in P2 and 4 clades and 7 clusters were detected in P3. In addition, allelic information was observed where the frequency of p and q alleles were observed 0.093 and 0.907 in P1, 0.076 and 0.924 in P2, 0.074 and 0.926 in P3 respectively. The average gene diversity was observed highest in P2 (0.132) followed by P3 (0.131) and P1 (0.121) respectively.

Keywords: genetic diversity, Monopterus cuchia, population, RAPD, Bangladesh

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Authors: Mahmoud Huleihil

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In this study, the performance of a thermodynamic gas cycle of magnetohydrodynamic (MHD) power generation is considered and presented in terms of power efficiency curves. The dissipation mechanisms considered include: fluid friction modeled by means of the isentropic efficiency of the compressor, heat transfer leakage directly from the hot reservoir to the cold heat reservoir, and constant velocity of the MHD generator. The study demonstrates that power and efficiency vanish at the extremes of both slow and fast operating conditions. These points are demonstrated on power efficiency curves and the locus of efficiency at maximum power and the locus of maximum efficiency. Qualitatively, the considered loss mechanisms have a similar effect on the efficiency at maximum power operation and on maximum efficiency operation, thus these efficiencies are reduced, even for small values of the loss mechanisms.

Keywords: magnetohydrodynamic generator, electrical efficiency, maximum power, maximum efficiency, heat engine

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Authors: Louaifi Hamaili Samira, Mataoui Amina, Cheraitia Tadjeddine

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This investigation proposes a numerical analysis of two turbulent parallel jets impinging a heated plate. The heat transfer enhancement is carried out according of the main parameters of the jet-wall interaction. The numerical solution of the stationary equations (RANS) is performed by the finite volume method using the k - ε model. A parametric study is performed to evaluate simultaneously the effect of nozzle-plate distance and velocity ratios in the range 0≤λ≤1. It is found that good local cooling is obtained for λ= 0.25 when the impinging distance is between 4w and 8w than for velocity ratios λ=1 and λ= 0.75. On the other hand, for impinging distances exceeding 8w, the velocity ratio λ =0.75 is more appropriate for good local cooling of the plate.

Keywords: two unequal jets, turbulence, mixing, heat transfer, CFD

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Authors: Samira Ali

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Aim: The purpose of this study was to describe nurses’ potential use of power levels to influence the standardization of nursing terminology (SNT) in electronic health records. Also, to examine the relationship between nurses’ use of power levels and variables such as position, communication and the potential goal of achieving SNT in electronic health records. Background: In an era of evidence-based nursing care, with an emphasis on nursing’s ability to measure the care rendered and improve outcomes of care, little is known about the nurse’s potential use of their power to SNT in electronic health records and lack of use of an SNT in electronic health records. Method: This descriptive, correlational, and cross-sectional study was conducted using survey methodology to assess the nurse’s use of power to influence the SNT in electronic health records. The Theory of Group Power within Organizations (TGPO) provided the conceptual framework for this study. A total of (n=232) nurses responded to the survey, posted on three nursing organizations’ websites. Results revealed the mean Cronbach’s alpha of the subscales was .94, suggesting high internal consistency. The mean power capability score was moderately high, at 134.22 (SD = 18.49). Power Capacity was significantly correlated with Power Capability (r = .96, p < .001). Power Capacity subscales were significantly correlated with Power Capacity and Power Capability. Conclusion: The mean Cronbach’s alpha of the subscales was .94 suggestive of reliability of the instrument. Nurses could potentially use power to achieve their goals, such as the implementation of SNT in electronic health records.

Keywords: nurses, power, actualized power, nursing terminology, electronic health records

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Authors: Tahir Mehmood, Mumtaz Akhter

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The global need for conflict management is greater now in the early 21st century than ever before. According to UNESCO, half of the world’s 195 countries will have to expand their stock of educationist significantly, some by tens of thousands, if the goal development targets are desired to achieve. Socioeconomic inequities, political instability, demographic changes and crises such as the HIV/AIDs epidemic have engendered huge shortfalls in teacher supply and low teacher quality in many developing countries. Education serves as back bone in development process. Open learning and distance education programs are serving as pivotal part of development process. It is now clear that ‘bricks and mortar’ approaches to expanding teacher education may not be adequate if the current and projected shortfalls in teacher supply and low teacher quality are to be properly addressed. The study is designed to measure the perceptions of teaching learning community about conflict management with special reference to open and distance learning. It was descriptive study which targeted teachers, students, community members and experts. Data analysis was carried out by using statistical techniques served by SPSS. Findings reflected that audience perceives open and distance learning as change agent and as development tool. It is noticed that target audience has driven prominent performance by using facility of open and distance learning.

Keywords: conflict management, open and distance learning, teachers, students

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Authors: Imen Aribi Ben Amor

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The aim of the present study is to analyze the performance of requests in emails among a group of Tunisian postgraduate students. It also seeks to determine the influence of the social factors on the participants’ requests performance. For this purpose, the data were collected using a discourse completion test (DCT). Accordingly, 42 Tunisian postgraduate students were asked to respond in English to eight different situations in which they carried out the speech act of request in emails. The data were analyzed based on the degree of directness. A detailed analysis of the head acts found in the DCT revealed that Tunisian Postgraduate students use a varied repertoire of request strategies (direct, conventionally indirect and non-conventionally indirect) but at the same time rely heavily on direct request strategies. They tended to address their requestees directly except for distant superiors. DCT results suggest that the participants are to some extent aware of the influence of the ranking of imposition and social distance but fail to acknowledge the weight of social power when performing requests in emails. The preference of the participants to use direct strategies may be the result of the effect of Tunisian culture and the negative transfer of Tunisian communicative strategies. Accordingly, this study suggests some pedagogical implications and suggestions for Tunisian EFL (English as a Foreign Language) instructors. They are required to pay closer attention to the pragmalinguistic nuances of the ways in which requests in emails are realized. Teachers can also help students understand academic email etiquettes by explicitly explaining what they expect in the student email. Thus, EFL teachers and syllabus designers should devote more attention to developing EFL learners’ pragmatic competence through teaching L2 pragmatics.

Keywords: directness, ranking of imposition, request strategies, social distance, social power

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Authors: Calogero Lo Destro

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Numerous nations around the world are facing exceptional challenges in employing measures to stop the spread of COVID-19. Following the recommendations of the World Health Organization, a series of preventive measures have been adopted. However, individuals must comply with these rules and recommendations in order to make these measures effective. While COVID-19 was climaxing, it seemed of crucial importance to analyze which psychosocial factors contribute to the acceptance of such preventive behavior, thus favoring the management of COVID-19 worldwide health crisis. In particular, the identification of aspects related to obstacles and facilitation of adherence to social distancing has been considered crucial in the containment of the virus spread. Since the virus was firstly detected in China, Asian people could be considered a relevant outgroup targeted for exclusion. We also hypothesized social distance could be influenced by characteristics of the target, such as smiling or coughing. 260 participants participated in this research on a voluntary basis. They filled a survey designed to explore a series of COVID-19 measures (such as exposure to virus and fear of infection). We also assessed participants state and trait anxiety. The dependent variable was social distance, based on a measure of seating distance designed ad hoc for the present work. Our hypothesis that participants could report greater distance in response to Asian people was not confirmed. On the other hand, significantly lower distance in response to smiling compared to coughing targets was reported. Adopting a regression analysis model, we found that participants' social distance, in response to both coughing and smiling targets, was predicted by fear of infection and by the perception COVID-19 could become a pandemic. Social distance in response to the coughing target was also significantly and positively predicted by age and state anxiety. In summary, the present work has sought to identify a set of psychological variables, which may still be predictive of social distancing.

Keywords: COVID-19, social distancing, health, preventive behaviors, risk of infection

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Authors: Satpal Yadav, Ashish Phulkar, Krishna K. Sahu

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Aim: The research aims at doing a 3 Dimension biomechanical analysis in the shot put techniques of International throwers to evaluate the performance. Research Method: The researcher adopted the descriptive method and the data was subjected to calculate by using Pearson’s product moment correlation for the correlation of the biomechanical parameters with the performance of shot put throw. In all the analyses, the 5% critical level (p ≤ 0.05) was considered to indicate statistical significance. Research Sample: Eight (N=08) international shot putters using rotational/glide technique in male category was selected as subjects for the study. The researcher used the following methods and tools to obtain reliable measurements the instrument which was used for the purpose of present study namely the tesscorn slow-motion camera, specialized motion analyzer software, 7.260 kg Shot Put (for a male shot-putter) and steel tape. All measurement pertaining to the biomechanical variables was taken by the principal investigator so that data collected for the present study was considered reliable. Results: The finding of the study showed that negative significant relationship between the angular velocity right shoulder, acceleration distance at pre flight (-0.70), (-0.72) respectively were obtained, the angular displacement of knee, angular velocity right shoulder and acceleration distance at flight (0.81), (0.75) and (0.71) respectively were obtained, the angular velocity right shoulder and acceleration distance at transition phase (0.77), (0.79) respectively were obtained and angular displacement of knee, angular velocity right shoulder, release velocity shot, angle of release, height of release, projected distance and measured distance as the values (0.76), (0.77), (-0.83), (-0.79), (-0.77), (0.99) and (1.00) were found higher than the tabulated value at 0.05 level of significance. On the other hand, there exists an insignificant relationship between the performance of shot put and acceleration distance [m], angular displacement shot, C.G at release and horizontal release distance on the technique of shot put.

Keywords: biomechanics, analysis, shot put, international throwers

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Authors: Jo-Han Chang, Chung-Jung Wu

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This study involves a design proposal. The objective of is to create a seat arrangement model for public reading spaces that enable free arrangement without disturbing the users. Through a subjective perception scale, this study explored whether distance between seats and direction of seats influence individual subjective perceptions in a public reading space. This study also involves analysis of user subjective perceptions when reading in the settings on 3 seats at different directions and with 5 distances between seats. The results may be applied to public chair design. This study investigated that (a) whether different directions of seats and distances between seats influence individual subjective perceptions and (b) the acceptable personal space between 2 strangers in a public reading space. The results are shown as follows: (a) the directions of seats and distances between seats influenced individual subjective perceptions. (b) subjective evaluation scores were higher for back-to-back seat directions with Distances A (10 cm) and B (62 cm) compared with face-to-face and side-by-side seat directions; however, when the seat distance exceeded 114 cm (Distance C), no difference existed among the directions of seats. (c) regarding reading in public spaces, when the distance between seats is 10 cm only, we recommend arranging the seats in a back-to-back fashion to increase user comfort and arrangement of face-to-face and side- by-side seat directions should be avoided. When the seat arrangement is limited to face-to-face design, the distance between seats should be increased to at least 62 cm. Moreover, the distance between seats should be increased to at least 114 cm for side- by-side seats to elevate user comfort.

Keywords: individual subjective perceptions, personal space, seat arrangement, direction, distances

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Authors: Pedro Esteban

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Today’s electrical networks, including microgrids, are evolving into smart grids. The smart grid concept brings the idea that the power comes from various sources (continuous or intermittent), in various forms (AC or DC, high, medium or low voltage, etc.), and it must be integrated into the electric power system in a smart way to guarantee a continuous and reliable supply that complies with power quality and energy efficiency standards and grid code requirements. This idea brings questions for the different players like how the required power will be generated, what kind of power will be more suitable, how to store exceeding levels for short or long-term usage, and how to combine and distribute all the different generation power sources in an efficient way. To address these issues, there has been lots of development in recent years on the field of on-grid and off-grid hybrid power systems (HPS). These systems usually combine one or more modes of electricity generation together with energy storage to ensure optimal supply reliability and high level of energy security. Hybrid power systems combine power generation and energy storage technologies together with real-time energy management and innovative power quality and energy efficiency improvement functionalities. These systems help customers achieve targets for clean energy generation, they add flexibility to the electrical grid, and they optimize the installation by improving its power quality and energy efficiency.

Keywords: microgrids, hybrid power systems, energy storage, power quality improvement

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Authors: Daeung Jung

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Background: In case of patients with missing teeth, multiple implant restoration has been widely used and is inevitable. To increase its survival rate, it is important to understand the influence of different implant designs on inter-implant crestal bone resorption. There are several implant systems designed to minimize loss of crestal bone, and the Astra Tech and Brånemark Implant are two of them. Aim/Hypothesis: The aim of this 10-year study was to compare the height of inter-implant bone crest in two implant systems; the Astra Tech and the Brånemark implant system. Material and Methods: In this retrospective study, 40 consecutively treated patients were utilized; 23 patients with 30 sites for Astra Tech system and 17 patients with 20 sites for Brånemark system. The implant restoration was comprised of splinted crown in partially edentulous patients. Radiographs were taken immediately after 1st surgery, at impression making, at prosthetics setting, and annually after loading. Lateral distance from implant to bone crest, inter-implant distance was gauged, and crestal bone height was measured from the implant shoulder to the first bone contact. Calibrations were performed with known length of thread pitch distance for vertical measurement, and known diameter of abutment or fixture for horizontal measurement using ImageJ. Results: After 10 years, patients treated with Astra Tech implant system demonstrated less inter-implant crestal bone resorption when implants had a distance of 3mm or less between them. In cases of implants that had a greater than 3 mm distance between them, however, there appeared to be no statistically significant difference in crestal bone loss between two systems. Conclusion and clinical implications: In the situation of partially edentulous patients planning to have more than two implants, the inter-implant distance is one of the most important factors to be considered. If it is impossible to make sure of having sufficient inter-implant distance, the implants with less micro gap in the fixture-abutment junction, less traumatic 2nd surgery approach, and the adequate surface topography would be choice of appropriate options to minimize inter-implant crestal bone resorption.

Keywords: implant design, crestal bone loss, inter-implant distance, 10-year retrospective study

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Authors: Mahdi Zolfaghari, Seyed Hossein Hosseinian, Hossein Askarian Abyaneh, Mehrdad Abedi

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This paper presents a virtual active power filter (VAPF) using vehicle to grid (V2G) technology to maintain power quality requirements. The optimal discrete operation of the power converter of electric vehicle (EV) is based on recognizing desired switching states using the model predictive control (MPC) algorithm. A fast dynamic response, lower total harmonic distortion (THD) and good reference tracking performance are realized through the presented control strategy. The simulation results using MATLAB/Simulink validate the effectiveness of the scheme in improving power quality as well as good dynamic response in power transferring capability.

Keywords: electric vehicle, model predictive control, power quality, V2G technology, virtual active power filter

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Authors: F. Benhamida, A. Graa, L. Benameur, I. Ziane

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The state estimation of the electrical power system operation state is very important for supervising task. With the nonlinearity of the AC power flow model, the state estimation problem (SEP) is a nonlinear mathematical problem with many local optima. This paper treat the mathematical model for the SEP and the monitoring of the nonlinear systems of great dimensions with an application on power electrical system, the modelling, the analysis and state estimation synthesis in order to supervise the power system behavior. in fact, it is very difficult, to see impossible, (for reasons of accessibility, techniques and/or of cost) to measure the excessive number of the variables of state in a large-sized system. It is thus important to develop software sensors being able to produce a reliable estimate of the variables necessary for the diagnosis and also for the control.

Keywords: power system, state estimation, robustness, observability

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Authors: Abdulrahman A. Bahaddad, Mohammed Beshir

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The objective of this paper is to demonstrate and describe eight different types of power generation technologies and to understand the history and future trends of each technology. In addition, a comparative analysis between these technologies will be presented with respect to their cost analysis and associated performance.

Keywords: conventional power generation, economic analysis, environmental impact, renewable energy power generation

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Authors: Anna Crivellari, Valerio Cozzani

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Even though most of the electricity produced in the entire world still comes from fossil fuels, new policies are being implemented in order to promote a more sustainable use of energy sources. Offshore renewable resources have become increasingly attractive thanks to the huge entity of power potentially obtained. However, the intermittent nature of renewables often limits the capacity of the systems and creates mismatches between supply and demand. Hydrogen is foreseen to be a promising vector to store and transport large amounts of excess renewable power by using existing oil and gas infrastructure. In this work, an offshore hybrid energy system integrating wind energy conversion with hydrogen production was conceptually defined and applied to offshore gas platforms. A techno-economic analysis was performed by considering two different locations for the installation of the innovative power system, i.e., the North Sea and the Adriatic Sea. The water depth, the distance of the platform from the onshore gas grid, the hydrogen selling price and the green financial incentive were some of the main factors taken into account in the comparison. The results indicated that the use of well-defined indicators allows to capture specifically different cost and revenue features of the analyzed systems, as well as to evaluate their competitiveness in the actual and future energy market.

Keywords: cost analysis, energy efficiency assessment, hydrogen production, offshore wind energy

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Authors: Manisha Dubey, Gaurav Gupta, Anoop Arya

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The demand for power supply increases day by day in developing countries like India henceforth demand of reactive power support in the form of ancillary services provider also has been increased. The multi-line and multi-type Flexible alternating current transmission system (FACTS) controllers are playing a vital role to regulate power flow through the transmission line. Unified power flow controller and interline power flow controller can be utilized to control reactive power flow through the transmission line. In a restructured power system, the demand of such controller is being popular due to their inherent capability. The transmission pricing by using reactive power cost allocation through modified matrix methodology has been proposed. The FACTS technologies have quite costly assembly, so it is very useful to apportion the expenses throughout the restructured electricity industry. Therefore, in this work, after embedding the FACTS devices into load flow, the impact on the costs allocated to users in fraction to the transmission framework utilization has been analyzed. From the obtained results, it is clear that the total cost recovery is enhanced towards the Reactive Power flow through the different transmission line for 5 bus test system. The fair pricing policy towards reactive power can be achieved by the proposed method incorporating FACTS controller towards cost recovery of the transmission network.

Keywords: interline power flow controller, transmission pricing, unified power flow controller, cost allocation

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Authors: Ju-Na Hwang, Min-Hae Park, Kee-Joe Lim

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Many studies have been conducted on DC transmission. Of power apparatus for DC transmission, High Voltage Direct Current (HVDC) cable systems are being evaluated because of the increase in power demand and transmission distance. Therefore, dc insulation characteristics of Liquid Silicone Rubber (LSR), which has various advantages such as short curing time and the ease of maintenance, were investigated to assess its performance as a HVDC insulation material for cable joints. The electrical performance of LSR added to Nano-Aluminum Trihydrate (ATH) was confirmed by measurements of the breakdown strength and electrical conductivity. In addition, field emission scanning electron microscope (FE-SEM) was used as a means of confirmation of nano-filler dispersion state. The LSR nano-composite was prepared by compounding LSR filled nano-sized ATH filler. The DC insulation properties of LSR added to nano-sized ATH fillers were found to be superior to those of the LSR without filler.

Keywords: liquid silicone rubber, nano-composite, HVDC insulation, cable joints

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Authors: Yousfi Abdelkader, Chaker Abdelkader, Bot Youcef

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This article proposes a five-level shunt active power filter for power quality improvement using a interval type-2 fuzzy logic controller (IT2 FLC). The reference compensating current is extracted using the P-Q theory. The majority of works previously reported are based on two-level inverters with a conventional Proportional integral (PI) controller, which requires rigorous mathematical modeling of the system. In this paper, a IT2 FLC controlled five-level active power filter is proposed to overcome the problem associated with PI controller. The IT2 FLC algorithm is applied for controlling the DC-side capacitor voltage as well as the harmonic currents of the five-level active power filter. The active power filter with a IT2 FLC is simulated in MATLAB Simulink environment. The simulated response shows that the proposed shunt active power filter controller has produced a sinusoidal supply current with low harmonic distortion and in phase with the source voltage.

Keywords: power quality, shunt active power filter, interval type-2 fuzzy logic controller (T2FL), multilevel inverter

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Authors: Ravi Chaithanya Mysa, Abouzar Kaboudian, Boo Cheong Khoo, Rajeev Kumar Jaiman

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The phenomenon of vortex-induced vibration has applications in off-shore industry, power transmission, energy extraction, etc. Two cylinders in crossflow whose centers are displaced in transverse direction are considered in the present work. The effects of the gap distance between the cylinders on the vortex shedding are presented. The inline distance between the cylinder centers is kept at zero. Two setups are considered for the study: first, we assume the two cylinders vibrate as a single rigid body mounted on a spring, and in the other case, each cylinder is mounted on a separate spring with no rigid connection to the other cylinder. The study focuses on the effect of transverse gap on the fluid-structure coupled response of two setups mentioned and corresponding flow contours. Incompressible flow is assumed in the Eulerian framework. The cylinder movement is modeled by a single degree of freedom rigid body motion (translational motion) in the Lagrangian framework. The governing equations were numerically solved by standard Petrov-Galerkin second order finite element schemes.

Keywords: cross-flow, vortex-induced vibrations, cylinder, close proximity

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Authors: Tlotlollo Sidwell Hlalele, Shengzhi Du

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High voltage transmission is the most pivotal process in the electrical power industry. It requires a robust infrastructure that can last for decades without causing impairment in human life. Due to the so-called global warming, power transmission system has started to experience some challenges which could presumably escalate more in future. These challenges are earthquake resistance, transmission power losses, and high electromagnetic field. In this paper, research efforts aim to address these challenges are discussed. We focus in particular on the research in regenerative electric energy such as: wind, hydropower, biomass and sea-waves based on the energy storage and transmission possibility. We conclude by drawing attention to specific areas that we believe need more research.

Keywords: power transmission, regenerative energy, power quality, energy storage

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Authors: Jörg Lenhardt, Wolfram Schiffmann, Jörg Keller

Abstract:

While the feature sizes of recent Complementary Metal Oxid Semiconductor (CMOS) devices decrease the influence of static power prevails their energy consumption. Thus, power savings that benefit from Dynamic Frequency and Voltage Scaling (DVFS) are diminishing and temporal shutdown of cores or other microchip components become more worthwhile. A consequence of powering off unused parts of a chip is that the relative difference between idle and fully loaded power consumption is increased. That means, future chips and whole server systems gain more power saving potential through power-aware load balancing, whereas in former times this power saving approach had only limited effect, and thus, was not widely adopted. While powering off complete servers was used to save energy, it will be superfluous in many cases when cores can be powered down. An important advantage that comes with that is a largely reduced time to respond to increased computational demand. We include the above developments in a server power model and quantify the advantage. Our conclusion is that strategies from datacenters when to power off server systems might be used in the future on core level, while load balancing mechanisms previously used at core level might be used in the future at server level.

Keywords: power efficiency, static power consumption, dynamic power consumption, CMOS

Procedia PDF Downloads 221

Authors: Watcharet Kongwarakom, Tosaphol Ratniyomchai, Thanatchai Kulworawanichpong

Abstract:

This paper presents a design and analysis of wireless charging lane system (WCLS) for light rail transit (LRT) by considering the performance of wireless charging, traffic conditions and energy consumption drawn by the LRT system. The dynamic of the vehicle movement in terms of the vehicle speed profile during running on the WCLS, a dwell time during stopping at the station for taking the WCLS and the capacity of the WCLS in each section are taken into account to alignment design of the WCLS. This paper proposes a case study of the design of the WCLS into 2 sub-cases including continuous and discontinuous WCLS with the same distance of WCLS in total. The energy consumption by the LRT through the WCLS with the different designs of the WCLS is compared to find out the better configuration of those two cases by considering the best performance of the power transfer between the LRT and the WCLS.

Keywords: Light rail transit, Wireless charging lane, Energy consumption, Power transfer

Procedia PDF Downloads 154

Authors: Paolo Fantozzi, Luigi Laura, Umberto Nanni

Abstract:

The problem of Entity relation discovery in structured data, a well covered topic in literature, consists in searching within unstructured sources (typically, text) in order to find connections among entities. These can be a whole dictionary, or a specific collection of named items. In many cases machine learning and/or text mining techniques are used for this goal. These approaches might be unfeasible in computationally challenging problems, such as processing massive data streams. A faster approach consists in collecting the cooccurrences of any two words (entities) in order to create a graph of relations - a cooccurrence graph. Indeed each cooccurrence highlights some grade of semantic correlation between the words because it is more common to have related words close each other than having them in the opposite sides of the text. Some authors have used sliding windows for such problem: they count all the occurrences within a sliding windows running over the whole text. In this paper we generalise such technique, coming up to a Weighted-Distance Sliding Window, where each occurrence of two named items within the window is accounted with a weight depending on the distance between items: a closer distance implies a stronger evidence of a relationship. We develop an experiment in order to support this intuition, by applying this technique to a data set consisting in the text of the Bible, split into verses.

Keywords: cooccurrence graph, entity relation graph, unstructured text, weighted distance

Procedia PDF Downloads 154

Authors: M. R. Bengourina, M. Rahli, L. Hassaine, S. Saadi

Abstract:

In this study, we present a control method entitled virtual flux direct power control of a grid connected photovoltaic system associated with an active power filter. The virtual flux direct control of power (VF-DPC) is employed for the calculation of reference current generation. In this technique, the switches states of inverter are selected from a table of switching based on the immediate errors between the active and reactive powers and their reference values. The objectives of this paper are the reduction of Total Harmonic Distortion (THD) of source current, compensating reactive power and injecting the maximum active power available from the PV array into the load and/or grid. MATLAB/SIMULINK simulations are provided to demonstrate the performance of the proposed approach.

Keywords: shunt active power filter, VF-DPC, photovoltaic, MPPT

Procedia PDF Downloads 323