201 research outputs found

    Coincidence of Fixed Points with Mixed Monotone Property

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                  الغرض من هذا البحث استعراض واثبات النقاط الصامدة الثنائية للدوال الذاتية التي تحقق الشرط  مع التعابير النسبية في الفضاءات المترية الكاملة  المرتبة جزئيا والتي تتضمن دوال المسافة بخاصية ال (MP). تعمل النتائج التي حصلنا عليها على تحسين وتوحيد العديد من النتائج في مبرهنات النقطة الصامدة الثنائية وتعميم بعض النتائج الحديثة في الفضاء المتري المرتب جزئيا. تم إعطاء مثال لاظهار صحة نتيجتنا الرئيسية .The purpose of this paper is to introduce and prove some coupled coincidence fixed point theorems for self mappings satisfying -contractive condition with rational expressions on complete partially ordered metric spaces involving altering distance functions with mixed monotone property of the mapping. Our results improve and unify a multitude of coupled fixed point theorems and generalize some recent results in partially ordered metric space. An example is given to show the validity of our main result.

    Doppler Frequency Estimation for a Maneuvering Target Being Tracked by Passive Radar Using Particle Filter

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    In this paper, we estimate Doppler frequency of a maneuvering target being tracked by passive radar using two types of particle filter, the first is “Maximum Likelihood Particle Filter” (MLPF) and the second is “Minimum Variance Particle filter” (MVPF). By simulating the passive radar system that has the bistatic geometry “Digital Video Broadcasting-Terrestrial (DVB-T) transmitter / receiver” with these two types, we can estimate the Doppler frequency of the maneuvering target and compare the simulation results for deciding which type gives better performanc

    Integrated control and protection architecture for islanded PV-battery DC microgrids:Design, analysis and experimental verification

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    Direct current (dc) microgrids have gained significant interest in research due to dc generation/storage technologies—such as photovoltaics (PV) and batteries—increasing performance and reducing in cost. However, proper protection and control systems are critical in order to make dc microgrids feasible. This paper aims to propose a novel integrated control and protection scheme by using the state-dependent Riccati equation (SDRE) method for PV-battery based islanded dc microgrids. The dc microgrid under study consists of photovoltaic (PV) generation, a battery energy storage system (BESS), a capacitor bank and a dc load. The aims of this study are fast fault detection and voltage control of the dc load bus. To do so, the SDRE observer-controller—a nonlinear mathematical model—is employed to model the operation of the dc microgrid. Simulation results show that the proposed SDRE method is effective for fault detection and robust against external disturbances, resulting in it being capable of controlling the dc load bus voltage during disturbances. Finally, the dc microgrid and its proposed protection scheme are implemented in an experimental testbed prototype to verify the fault detection algorithm feasibility. The experimental results indicate that the SDRE scheme can effectively detect faults in a few milliseconds

    Comorbidity of Learning Disorders and Attention Deficit Hyperactivity Disorder in a Sample of Omani Schoolchildren

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    Objectives: The estimated worldwide prevalence of learning disorders (LDs) is approximately 2‒10% among school-aged children. LDs have variable clinical features and are often associated with other disorders. This study aimed to examine the comorbidity of LDs and attention deficit hyperactivity disorder (ADHD) among a sample of schoolchildren in Oman. Methods: This study was conducted between January 2014 and January 2015 at the Sultan Qaboos University, Muscat, Oman. The Learning Disabilities Diagnostic Inventory (LDDI) and the 28-item version of the Conners’ Teacher Rating Scale was completed by classroom teachers to determine the existence of LD and ADHD symptoms in 321 children in grades 1‒4 who had been referred to a learning support unit for LDs from elementary schools in Muscat. Results: The mean age of the students was 8.5 years. Among the cohort, 30% were reported to have symptoms of ADHD, including conduct problems (24%), hyperactivity (24%) and inattentivepassive behaviours (41%). Male students reportedly exhibited greater conduct problems and hyperactivity than females. However, there were no gender differences noted between LDDI scores. Conclusion: This study suggests that Omani schoolchildren with LDs are likely to exhibit signs of ADHD. The early identification of this disorder is essential considering the chronic nature of ADHD. For interventional purposes, multidisciplinary teams are recommended, including general and special educators, clinical psychologists, school counsellors, developmental or experienced general paediatricians and child psychiatrists

    Construction of a Scale for Emotions Management of the Educational Supervisors in the Sultanate of Oman

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    This study aimed to construct of a scale for emotions management of the educational supervisors in the Sultanate of Oman. It aimed to find out its psychometric properties in terms of validity, reliability, and performance norms. The sample size consisted of 335 supervisors from the Omani educational governorate. The scale was applied during the first semester of the academic year 2010-2011. The validity was verified by three methods: face validity, factorialvalidity and concurrentvalidity. Since there were no significant differences in the scale averages of males and females, the norms were derived for both males and females combined. Finally, a number of recommendations and suggestions have been introduced

    Does job value boost self-efficacy and protect against burnout among teachers in Oman?

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    Introduction. The purpose of this study was to examine if the perception of teaching value and a teacher's self-efficacy (SE) are related to burnout. Previous research has shown a strong relation between teachers SE and burnout. Rarely, however, job value has been included in any of the previous studies. Method. A stratified random sample (N =2446) of Omani teachers was drawn. Three measures: Job value, Maslach burnout inventory (MBI) and the teachers' sense of efficacy scale (TSES) were used. Confirmatory factor analysis was performed to test the proposed factor structure of the measures as well as the proposed structural model. Results. The invariance tests proved that the structure of constructs and the relations between constructs were invariant across gender. Job value significantly related to both SE and burnout dimensions. Consistent with predictions, SE of student engagement related to all three burnout dimensions; whereas the other two dimensions of SE didn’t relate to burnout dimensions in the expected direction. Job value and SE explained significant variances in each of the burnout dimensions. Discussion and Conclusion. The results of this study highlight the importance of job value and SE of engaging students as cognitive self-regulatory mechanisms used in the stressful situations like teaching and to help control stress and burnout. Ministry of education, media and socity at large should be aware of the social status of teaching and teachers and provide more respect to the teachers and their job. Such respect would improve the morale of teachers and help them become more efficacious and less exhausted

    Low back pain education and short term quality of life: a randomized trial

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    BACKGROUND: Different interventions can reduce the burden of the chronic low back pain. One example is the use of a 'Back School Programme'. This is a brief therapy that uses a health education method to empower participants through a procedure of assessment, education and skill development. This study aimed to evaluate to what extent the programme could improve quality of life in those who suffer from the condition. METHODS: This was a randomized controlled trial. One-hundred and two female patients with low back pain (n = 102) were randomly allocated into two groups, matched in terms of age, weight, education, socioeconomic status, occupation and some aspects of risk behavior. Group 1 (back school group, n = 50) but not group 2 (clinic group, n = 52) received the 'Back School Programme'. Then quality of life using the Short Form Health Survey (SF-36) was assessed at two time points: at baseline and at three months follow-up. The findings were compared both within and between two groups. RESULTS: The 'Back School Programme' was effective in improving patients' quality of life; significant differences were found on all eight subscales of the SF-36 for group 1. In the clinic group (group 2), improvement was observed on three scales (bodily pain, vitality and mental health) but these improvements were less than in group 1. The mean improvement over all eight subscales of the SF-36 was significantly better for the 'Back School Programme' group. CONCLUSION: The 'Back School Programme' is an effective intervention and might improve the quality of life over a period of 3 months in patients who experience chronic low back pain

    Factors Affecting the Reluctance to Pursue Teaching as a Career from the Perspective of Students in the Sultanate of Oman: A mixed-approach Investigation

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    هدفت الدراسة الحالية إلى الكشف عن العوامل المؤثرة في عزوف الطلبة عن مهنة التدريس بسلطنة عمان. استخدمت الدراسة المنهج المختلط، حيث تم جمع البيانات الكمية من خلال مقياس العوامل المؤثرة على اختيار مهنة التدريس بعد تعريبه وتكييفه لمجتمع الدراسة المكون من طلبة الصفوف 10-12 (ن= 3455)، أما البيانات النوعية فقد تم جمعها من خلال مجموعات النقاش البؤرية مع طلبة هذه الصفوف (ن= 253). أشارت النتائج إلى أن العوامل المؤثرة في عزوف الطلبة عن مهنة التدريس تمحورت حول: صعوبة المهنة، وقلة حوافزها المادية، وتدني المكانة الاجتماعية لها مقارنة بالمهن الأخرى، بينما بينت نتائج مجموعات النقاش البؤرية وجود آراء إيجابية وسلبية للمهنة، ووجود تحديات أبرزها: صعوبة التعامل مع عدد كبير من الطلبة، وتوقف ترقيات المعلمين، وتعيين المعلمين بعيدا عن أماكن إقامتهم. كما بين أغلبية طلبة المدارس من الجنسين بأنه ليس لديهم الرغبة والاتجاه الإيجابي لاختيار التدريس كمهنة المستقبل. كما أشارت نتائج الدراسة المتعلقة بالفروق بين الجنسين إلى وجود فروق دالة إحصائيا لصالح الذكور في العزوف عن مهنة التدريس

    Energy loss in a strongly coupled anisotropic plasma

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    We study the energy loss of a rotating infinitely massive quark moving, at constant velocity, through an anisotropic strongly-coupled N=4 plasma from holography. It is shown that, similar to the isotropic plasma, the energy loss of the rotating quark is due to either the drag force or radiation with a continuous crossover from drag-dominated regime to the radiation dominated regime. We find that the anisotropy has a significant effect on the energy loss of the heavy quark, specially in the crossover regime. We argue that the energy loss due to radiation in anisotropic media is less than the isotropic case. Interestingly this is similar to analogous calculations for the energy loss in weakly coupled anisotropic plasma.Comment: 26+1 pages, 10 figures, typos fixe
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