Search results for: Ali Osman Güney

Authors: Ali Osman Güney, Bahattin Kanber

Abstract:

In this work, the effect of material type, diameter, orientation and closeness of fibers on the general performance of reinforced vulcanized rubbers are investigated using finite element method with experimental verification. Various fiber materials such as hemp, nylon, polyester are used for different fiber diameters, orientations and closeness. 3D finite element models are developed by considering bonded contact elements between fiber and rubber sheet interfaces. The fibers are assumed as linear elastic, while vulcanized rubber is considered as hyper-elastic. After an experimental verification of finite element results, the developed models are analyzed under prescribed displacement that causes tension. The normal stresses in fibers and shear stresses between fibers and rubber sheet are investigated in all models. Large deformation of reinforced rubber sheet also represented with various fiber conditions under incremental loading. A general assessment is achieved about best fiber properties of reinforced rubber sheets for tension-load conditions.

Keywords: reinforced vulcanized rubbers, fiber properties, out of plane loading, finite element method

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Authors: B. Güney, Ç. Teke

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In recent years, rapid and correct decision making is crucial for both people and enterprises. However, uncertainty makes decision-making difficult. Fuzzy logic is used for coping with this situation. Thus, fuzzy linear programming models are developed in order to handle uncertainty in objective function and the constraints. In this study, a problem of a factory in food industry is investigated, required data is obtained and the problem is figured out as a fuzzy linear programming model. The model is solved using Zimmerman approach which is one of the approaches for fuzzy linear programming. As a result, the solution gives the amount of production for each product type in order to gain maximum profit.

Keywords: food industry, fuzzy linear programming, fuzzy logic, linear programming

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Authors: Richard Fairchild, Abdullah Al-Ghazali, Yilmaz Guney

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This study analyses the relationship between managerial overconfidence, dividends, and firm value by developing theoretical models that examine the condition under which managerial overconfident, dividends, and firm value may be positive or negative. Furthermore, the models incorporate moral hazard, in terms of managerial effort shirking, and the potential for the manager to choose negative NPV projects, due to private benefits. Our models demonstrate that overconfidence can lead to higher dividends (when the manager is overconfident about his current ability) or lower dividends (when the manager is overconfident about his future ability). The models also demonstrate that higher overconfidence may result in an increase or a decrease in firm value. Numerical examples are illustrated for both models which interestingly support the models’ propositions.

Keywords: behavioural corporate finance, dividend policy, overconfidence, moral hazard

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Authors: Selin Guney, Andres Riquelme

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The traditional bio-economic method for fisheries modeling uses some estimate of the growth parameters and the system carrying capacity from a biological model for the population dynamics (usually a logistic population growth model) which is then analyzed as a traditional production function. The stock dynamic is transformed into a revenue function and then compared with the extraction costs to estimate the maximum economic yield. In this paper, the logistic population growth model for the population is combined with a forecast of the abundance and location of the stock by using a generalized additive model approach. The paper focuses on the Chilean hake population. This method allows for the incorporation of climatic variables and the interaction with other marine species, which in turn will increase the reliability of the estimates and generate better extraction paths for different conservation objectives, such as the maximum biological yield or the maximum economic yield.

Keywords: bio-economic, fisheries, GAM, production

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Authors: Osman Acar

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Sun tracking systems are the systems following the sun ray by a right angle or by predetermined certain angle. In this study, we used theoretical trajectory of sun for latitude of central Anatolia in Turkey. A two degree of freedom spherical mechanism was designed to have a large workspace able to follow the sun's theoretical motion by the right angle during the whole year. An inverse kinematic analysis was generated to find the positions of mechanism links for the predicted trajectory. Force and torque analysis were shown for the first day of the year.

Keywords: sun tracking, theoretical sun trajectory, spherical mechanism, inverse kinematic analysis

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Authors: Ahmed I. Osman, Jehad K. Abu-Dahrieh, Jillian M. Thompson, David W. Rooney

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Natural gas (the main constituent is Methane 95%) is considered as an alternative to petroleum for the production of synthetics fuels. Nowadays, methane combustion at low temperature has received much attention however; it is the most difficult hydrocarbon to be combusted. Co/Mo and (4:1 wt/wt) catalysts were prepared from a range of different precursors and used for the low temperature total methane oxidation (TMO). The catalysts were characterized by, XRD, BET and H2-TPR and tested under reaction temperatures of 250-400 °C with a GHSV= 36,000 mL g-1 h-1. It was found that the combustion temperature was dependent on the type of the precursor, and that those containing chloride led to catalysts with lower activity. The optimum catalyst was Co/Mo (4:1wt/wt) where greater than 20% methane conversion was observed at 250 °C. This catalyst showed a high degree of stability for TMO, showing no deactivation during 50 hours of time on stream.

Keywords: methane low temperature total oxidation, oxygen carrier, Co/Mo, Co/Mn

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Authors: Sertac Arslan, Guven Guney, Ayse Ipek Akyuz Unsal, Emre Demir, Buket Demirci

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Purpose: There is little histologic data concerning effects of nasal decongestants on the respiratory tract. We aimed to put forth the effects of nasal decongestants on the trachea and lower airways of rats. Materials and Methods: Four to six months old 60 male rats were randomly categorized into 6 groups. Experimental drugs were applied to the same nostril of rats twice daily for 8 weeks (Xylometazolin, Benzalkolyum, EDTA, Sorbitol and combined drug solutions). We applied normal saline solution (NaCl %0.9) for the control group. In the end, trachea and both lungs were dissected and kept in formaldehyde for histopathologic evaluation. Results: Inflammation and bronchial edema were most common findings. While all rats in sorbitol group had increased numbers of type 2 pneumocytes; 80% of BAC group had increased numbers of type 2 pneumocytes. Spillover of tracheal epithelium was seen mostly in sorbitol, EDTA and combined drug groups (60%, 87.5%, 50% respectively). Bronchial smooth muscle hypertrophy was seen mostly in BAC and EDTA group (70%, 62.5% respectively). The number of goblet cells showed the significant difference between control-combined drug (p=0.025) and control-BAC (p=0.001) groups. Conclusions: Nasal decongestants can cause permanent changes at lower respiratory tract in addition to changes in upper respiratory tract.

Keywords: decongestive agents, xylometazoline, lung, trachea

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Authors: Abdullah AlGhazali, Richard Fairchild, Yilmaz Guney

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We examine the effect of managerial overconfidence on UK firms’ payout policy for the period 2000 to 2012. The analysis incorporates, in addition to common firm-specific factors, a wide range of corporate governance factors and managerial characteristics that have been documented to affect the relationship between overconfidence and payout policy. Our results are robust to several estimation considerations. The findings show that the influence of overconfident CEOs on the amount of, and the propensity to pay, dividends is significant within the UK context. Specifically, we detect that there is a reduction in dividend payments in firms managed by overconfident managers compared to their non-overconfident counterparts. Moreover, we affirm that cash flows, firm size and profitability are positively correlated, while leverage, firm growth and investment are negatively correlated with the amount of and propensity to pay dividends. Interestingly, we demonstrate that firms with the potential for undervaluation reduce dividend payments. Some of the corporate governance factors are shown to motivate firms to pay more dividends while these factors seem to have no influence on the propensity to pay dividends. The results also show that in general higher overconfidence leads to more share repurchases but the lower total payout. Overall, managerial overconfidence should be considered as an important factor influencing payout policy in addition to other known factors.

Keywords: dividends, repurchases, UK firms, overconfidence, corporate governance, undervaluation

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Authors: Kemalettin Eryesil, Osman Esmen, Aykut Beduk

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In this study, it has been studied to determine the relationship between business performance and strategic flexibility, which is defined to be the strategic choice that provides the ability of rapidly responding the changes of the dynamic environment of the companies, for having competitive advantages. In this context a field study has been conducted over 56 companies, which are active in informatics and electronics sectors in TEKNOKENT. As a result of the study it has been determined that; strategic flexibility has an effect on business performance and there is a positive and statistically significant relationship between strategic flexibility and business performance.

Keywords: sustainable competition advantage, strategic flexibility, firm performance, TEKNOKENT

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Authors: Ali Osman Suiçmez, Emrah Deniz

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In this study, control experiments were made on a freeze drying system of which were built a prototype. In experiments, apple slices in different geometrical shapes were dried and drying curves were gained. Then, the shapes which were the fastest for drying were determined. Twenty samples for each apple shapes were put in the prototype and dried. After the experiments, the humidity ratio of the samples and water activity values of the samples have been obtained. Obtained results show that the prototype is working and by comparing the results the shape which dried fastest was determined.

Keywords: freeze drying, vacuum, energy consumption, drying process, apple

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Authors: Kerem Rızvanoglu, Serhat Güney, Betül Aydoğan, Emre Kızılkaya, Ayşegül Boyalı, Onurcan Güden

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This study investigates the urban experience of international students coming to Istanbul with exchange programs and reveals how locative media applications accompany their urban experiences. The sample of the research consists of international students who lived, perceived, and conceived the city on a daily basis during the academic year of 2022. Focusing on this particular sample would demonstrate the opportunities and authentic experiences offered by the city as well as the prevalent urban problems for the foreigners. In this regard, international students' urban experience in Istanbul, the blockages they encounter as resident tourists, the hotspots that the city offers, and the role of locative media in enriching the urban experience are the main axes to be evaluated. In the first step of the multi-staged research, we conduct an online qualitative survey with a sample; then, we evaluate the data obtained from the survey using cluster analysis to identify the urban experience, consumption habits, and tastes. In the final stage, digital ethnographic fieldwork will be carried out with representative personas identified by the cluster analysis. With this field research on the urban experience accompanied by locative media applications, suggestions will be developed by evaluating the opportunities these applications offer to enrich the urban practice of foreigners.

Keywords: digital ethnography, international students, locative media applications, urban experience

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Authors: Aykut Bedük, Kemalettin Eryeşil, Osman Eşmen

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The aim of this study is to examine the relationship between organizational commitment which is defined as a strong belief in and acceptance of the organization’s goals and values, and burnout syndrome and organizational cynicism. Accordingly, a field research based on survey method was conducted on the employees of a health institution operating in the province of Konya. The findings of the research show that there is a positive statistically significant relationship between organizational cynicism and burnout while there is a negative statistically significant relationship between organizational commitment and burnout. Furthermore, it has been also realized that there is a negative and statistically significant relationship between organizational commitment and organizational cynicism.

Keywords: burnout, organizational commitment, organizational cynicism, healthcare management

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Authors: Hilal Kivrak, Aykut ÇağLar, Nahit Aktaş, Ali Osman Solak

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At present, Cd/TiO₂ and CdTe/TiO₂ catalysts are prepared via sodium borohydride (NaBH4) reduction method. These catalysts are characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). These Cd/TiO₂ and CdTe/TiO₂ are employed as catalysts for the photocatalytic oxidation of glucose. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements are used to investigate their glucose electrooxidation activities of catalysts at long and under UV illumination (ʎ=354 nm). CdTe/TiO₂ catalyst is showed the best photocatalytic glucose electrooxidation activity compared to Cd/TiO₂ catalyst.

Keywords: cadmium, NaBH4 reduction method, photocatalytic glucose electrooxidation, Tellerium, TiO2

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Authors: Osman Okumuş

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The pandemic has significantly affected every aspect of life. Especially in recenttimes, as a result of this effect, we have come closer to technology. Distance education has taken the place of formal education rather than supporting formal education. Thiscreatednewexperiencesforbothteachersandstudents. This research focused on revealing the experiences of the same students in distance and formal education, especially in history lessons. In the study, which was designed as a case study, 20 students were interviewed through a semi-structured interview form prepared by the researcher. The results show that both learning environments provide students with important experiences. However, despite the fact that the students developed their digital competencies and experienced different learning environments, they focused on formal education in the name of socialization.

Keywords: history lessons, distance education, pandemic., formal education

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Authors: Fatma Gülden Şi̇mşek, Osman Meli̇h Can, Mehmet Yumak, Bora Gari̇pcan, Yekta Ülgen

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In this study, the impedance spectroscopy is used as a detection tool in order to characterize surface coating with graphene oxide. Gold electrodes are produced by standard lithography procedures and then coated with graphene oxide using self-assembly method. The impedance of redox solution through bare gold electrodes and graphene oxide coated gold electrodes is measured in the low and high frequency range. The graphene oxide coating reduces the impedance value of the gold electrode and this reduction is distinguishable in the low-frequency range.

Keywords: bioimpedance, electrode characterization, graphene oxide, gold electrodes, impedance spectroscopy

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Authors: M. N. Osman Zahid, K. Case, D. Watts

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This paper reports an advanced approach in the application of CNC machining for rapid manufacturing processes (CNC-RM). The aim of this study is to improve the quality of machined parts by introducing different cutting tools during finishing operations. As the cutting is performed in different directions, the surfaces presented on part can be classified into several categories. Therefore, suitable cutting tools are assigned to machine particular surfaces and to improve the quality. Experimental studies have been carried out by fabricating several parts based on the suggested approach. The results provide further support for implementing this approach in rapid machining processes.

Keywords: CNC machining, end mill tool, finishing operation, rapid manufacturing

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Authors: Alhaji Khuzaima Mohammed Osman, Zaeem Sheikh Abdul Wadudi Haruna

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This article aims to explore the crucial link between counter-terrorism efforts and the preservation of human security. As acts of terrorism continue to pose significant threats to societies worldwide, it is imperative to develop effective strategies that mitigate risks while safeguarding the rights and well-being of individuals. This paper discusses key aspects of counter-terrorism and human security, emphasizing the need for a comprehensive approach that integrates intelligence, prevention, response, and resilience-building measures. By highlighting successful case studies and lessons learned, this article provides valuable insights for policymakers, law enforcement agencies, and practitioners in their quest to address terrorism and foster human security.

Keywords: human security, risk mitigation, terrorist activities, civil liberties

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Authors: M. K. Mohd Safee, W. A. B. Wan Abas, F. Ibrahim, N. A. Abu Osman, N. A. Abdul Malik

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This paper investigates the activity of the rectus femoris (RF) and biceps femoris (BF) in healthy subjects during salat (prostration) and specific exercise (squat exercise) using electromyography (EMG). A group of undergraduates aged between 19 to 25 years voluntarily participated in this study. The myoelectric activity of the muscles were recorded and analyzed. The finding indicated that there were contractions of the muscles during the salat and exercise with almost same EMG’s level. From the result, Wilcoxon’s Rank Sum test showed significant difference between prostration and squat exercise (p < 0.05) but the differences was very small; RF (8.63% MVC) and BF (11.43% MVC). Therefore, salat may be useful in strengthening exercise and also in rehabilitation programs for lower limb activities. This pilot study conducted initial research into the bio mechanical responses of human muscles in various positions of salat.

Keywords: electromyography, exercise, muscle, salat

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Authors: Eyup Bayram Guzel, Osman Tunc

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People have been fairly interested in what technology offers to them around a scope of human necessities and it has become a part of human life. In this study, experimental studies were reviewed for the purpose of how technology helps language learners improve their phonemic awareness, reading comprehension and vocabulary development skills. As a conclusion, experimental studies demonstrated that students showed significant improvements up to 70% in phonological awareness, while they demonstrated up to 76% of improvements in reading comprehension and up to 77% in vocabulary development. The use of computer-assisted technologies and its positive outcomes were encouraged to be used more widely in order to meet the diverse needs of students.

Keywords: technology, phonemic awareness, reading comprehension, vocabulary development

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Authors: M. K. Mohd Safee, W. A. B. Wan Abas, F. Ibrahim, N. A. Abu Osman, N. A Abdul Malik

Abstract:

This paper investigates the activity of the rectus femoris (RF) and biceps femoris (BF) in healthy subjects during salat (prostration) and specific exercise (squat exercise) using electromyography (EMG). A group of undergraduates aged between 19 to 25 years voluntarily participated in this study. The myoelectric activity of the muscles were recorded and analyzed. The finding indicated that there were contractions of the muscles during the salat and exercise with almost same EMG’s level. From the result, Wilcoxon’s Rank Sum test showed significant difference between prostration and squat exercise (p<0.05) but the differences was very small; RF (8.63%MVC) and BF (11.43%MVC). Therefore, salat may be useful in strengthening exercise and also in rehabilitation programs for lower limb activities. This pilot study conducted initial research into the biomechanical responses of human muscles in various positions of salat.

Keywords: electromyography, exercise, muscle, salat

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Authors: Esra Güney, Tuba Uçar

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Aim: This study has been conducted for the purpose of determining the effects of fetal movement counting on antenatal maternal attachment. Material and Method: This research was conducted on the basis of the real test model with the pre-test /post-test control groups. The study population consists of pregnant women registered in the six different Family Health Centers located in the central Malatya districts of Yeşilyurt and Battalgazi. When power analysis is done, the sample size was calculated for each group of at least 55 pregnant women (55 tests, 55 controls). The data were collected by using Personal Information Form and MAAS (Maternal Antenatal Attachment Scale) between July 2015-June 2016. Fetal movement counting training was given to pregnant women by researchers in the experimental group after the pre-test data collection. No intervention was applied to the control group. Post-test data for both groups were collected after four weeks. Data were evaluated with percentage, chi-square arithmetic average, chi-square test and as for the dependent and independent group’s t test. Result: In the MAAS, the pre-test average of total scores in the experimental group is 70.78±6.78, control group is also 71.58±7.54 and so there was no significant difference in mean scores between the two groups (p>0.05). MAAS post-test average of total scores in the experimental group is 78.41±6.65, control group is also is 72.25±7.16 and so the mean scores between groups were found to have statistically significant difference (p<0.05). Conclusion: It was determined that fetal movement counting increases the maternal antenatal attachments.

Keywords: antenatal maternal attachment, fetal movement counting, pregnancy, midwifery

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Authors: Sarah K. Amer, Nagwa Badr, Osman Ibrahim, Ahmed Hamad

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This paper surveys the effectiveness of software process quality assurance frameworks, with some focus on Capability Maturity Model Integration (CMMI) - a framework that has become widely adopted in software organizations. The importance of quality improvement in software development, and the differences in the outcomes of quality framework implementation between Middle Eastern and North African (MENA-region) countries and non-MENA-region countries are discussed. The greatest challenges met in the MENA region are identified, with particular focus on Egypt and its rising software development industry.

Keywords: software quality, software process improvement, software development methodologies, capability maturity model integration

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Authors: Orhun Vural, Oguz Bayat, Rustu Akay, Osman N. Ucan

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This study presents a new parallel approach clustering of GPS data. Evaluation has been made by comparing execution time of various clustering algorithms on GPS data. This paper aims to propose a parallel based on neighborhood K-means algorithm to make it faster. The proposed parallelization approach assumes that each GPS data represents a vehicle and to communicate between vehicles close to each other after vehicles are clustered. This parallelization approach has been examined on different sized continuously changing GPS data and compared with serial K-means algorithm and other serial clustering algorithms. The results demonstrated that proposed parallel K-means algorithm has been shown to work much faster than other clustering algorithms.

Keywords: parallel k-means algorithm, parallel clustering, clustering algorithms, clustering on flowing data

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Authors: Nurullah Buker, Ezgi Karagoz, Yesim Salik Sengul, Sevay Alsen Guney, Gokhan Yoyler, Aylin Ozbek

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Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders with heterogeneous clinical features such as inattention, hyperactivity, and impulsivity. Many different types of exercise interventions were employed for children with ADHD. However, previous studies have usually examined the effects of non-specific exercise programs or short-term effects of exercise. The aim of this study is to investigate the effect of the Neurocognitive Exercise Program (NEP), which is a structured exercise program derived from Life Kinetik, and a relatively new for children with ADHD, on symptoms, attention, and dynamic balance in medication-naïve children with ADHD. Fourteen medication-naive children (7-12 years) with ADHD were included in the intervention group. NEP was performed once a week for ten weeks. The intervention group also performed a structured home exercise program for another six days, for ten weeks. The children in the intervention group were assessed at baseline, in the third month, in the sixth month, and in the twelfth month regarding ADHD-related symptoms, attention, and dynamic balance. Fifteen age-matched typically developing children were assessed once for establishing normative values. Hyperactivity-Impulsivity score and dynamic balance were found to improve after NEP in the ADHD group in the 3rd month (p<0.05). In addition, these results were similar for both groups after NEP and at the end of the 12th month (p>0.05). The NEP may provide beneficial effects on hyperactivity-impulsivity, oppositional defiant, and dynamic balance in children with ADHD, and the improvements may be maintained in the long term.

Keywords: ADHD, attention problems, dynamic balance, neurocognitive exercise

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Authors: Mostert Jacques, Gulseven Osman, Williams Courtney

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The Covid-19 pandemic caused unparalleled disruption in the lives of the majority of the world. This included school closures and introduction of Online Learning. In this article we investigated the impact of distance learning on the self-efficacy and anxiety levels experienced by educators in South Africa. We surveyed 60 respondents from Independent Schools using a Likert Scale rating of 0 to 4. The results suggested that despite experiencing moderate anxiety, educators showed a sense of high self-efficacy during distance learning. This was specifically true for those with underlying health concerns. There was no significant difference between how the different genders experienced anxiety and self-efficacy. Further research into the impact on learners’ anxiety levels during distance learning will provide policymakers and educators with a better understanding of how the use of technology is influencing the effectiveness of teaching, learning, and assessment.

Keywords: COVID-19, education, self-efficacy, anxiety

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Authors: Moustafa Osman Mohamed

Abstract:

This paper will explore the influence of energy sector in Arab Republic of Egypt which has shared its responsibilities of many environmental challenges as the second largest economy in the Middle East (after Iran). Air and water pollution, desertification, inadequate disposal of solid waste and damage to coral reefs are serious problems that influence environmental management in Egypt. The intensive reliance of high population density and strong industrial growth are wearing Egypt's resources, and the rapidly-growing population has forced Egypt to breakdown agricultural land to residential and relevant use of commercial ingestion. The depletion effects of natural resources impose the government to apply innovation techniques in emission control and focus on sustainability. The cogeneration will be presented to control thermal losses and increase efficiency of energy power system.

Keywords: cogeneration, environmental management, power electricity, energy indicators

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Authors: Muzeyyen Balcikanli, Selma Ozaslan, Osman Sahin, Burak Uzal, Erdogan Ozbay

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In this study, the effect of nano-CaCO3 replacement with cement on the nano-mechanical properties of cement paste was investigated. Hydrophobic and hydrophilic characteristics Two types of nano CaCO3 were replaced with Portland cement at 0, 0.5 and 1%. Water to (cement+nano-CaCO3) ratio was kept constant at 0.5 for all mixtures. 36 indentations were applied on each cement paste, and the values of nano-hardness and elastic modulus of cement pastes were determined from the indentation depth-load graphs. Then, by getting the average of them, nano-hardness and elastic modulus were identified for each mixture. Test results illustrate that replacement of hydrophilic n-CaCO3 with cement lead to a significant increase in nano-mechanical properties, however, replacement of hydrophobic n-CaCO3 with cement worsened the nano-mechanical properties considerably.

Keywords: nanoindenter, CaCO3, nano-hardness, nano-mechanical properties

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Authors: Emad A. M. Osman, Ahmed M. Abu-Bakr

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Compacted granular fill under shallow foundation is one of the oldest, cheapest, and easiest techniques to improve the soil characteristics to increase the bearing capacity and decrease settlement under footing. There are three main factors affecting the design of soil replacement to gain these advantages. These factors are the type of replaced soil, characteristics, and thickness. The first two factors can be easily determined by laboratory and field control. This paper emphasizes on how to determine the thickness accurately for footing under centric axial load by limit state design method. The advantages of the method are the way of determining the thickness (independent of experience) and it takes into account the replaced and original or underneath soil characteristics and reaches the goals of replaced soils economically.

Keywords: design of soil replacement, LSD method, soil replacement, soil improvement

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Authors: Mohammed Mahmoud Osman Ahmed, Akram Mohammad

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Flame dynamics in heated quartz glass channels of various aspect ratios (2,5,10,15) were experimentally investigated. A premixed Propane-air mixture was used for the reported experiments. Regarding micro-combustion, flame quenching is considered to be the most crucial problem to overcome first. Experiments were carried out on four channels with different aspect ratios. The results show that at a very low equivalence ratio ϕ=0.4, there is no flame inside the channels. The FREI condition (Flame with repetitive extinction and ignition) was overcome by increasing velocity and by making the channels more in contact with the external heater. The flame tested inside the channels at different locations for V=0.3 m/s or higher below V=0.65 m/s. The effects of equivalence ratio and flow velocity on the characteristics of combustion in the channels were examined. Different ways of flame propagation were observed in the current investigations based on how they appear as planar, concave and convex flames.

Keywords: flame stabilization, combustion, flame dynamics, small-scale channels, external heater

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Authors: Osman Kök, İlhami̇ Tüzün, Yaşar Aluç

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This study was conducted to explore the effect of direct current (DC) applications on the growth of microalgae Chlorella vulgaris KKU71, isolated from highly saline freshwater. Experiments were implemented based upon the cross-combinations of both the intensity and duration of electric applications, generating a full factorial design of 10V, 20V, 30V, and 5s, 30s, 60s, respectively. Growth parameters of cultures were monitored on Optical Density (OD), Cell Count (CC), Chlorophyll-a, b (Chl-a, b), and Total Carotenoids (TCar). All DC-assisted treatments stimulated the growth and thus led to higher values of growth parameters such as OD, CC, Chl-a, and TCar. Monotonically increasing with the intensity and duration of DC applications, wet and dry biomass yields of the harvested algae reached their highest level at 30V-60s in all sets of treatments. In addition, this increase between DC applications was listed as C(control)<10V<20V<30V and C<5s<30s<60s. As a result, direct current applications increased the biomass.

Keywords: Chlorella Vulgaris, direct current, growth, biomass

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