Basit Mesnetli Simetrik Çapraz- Ve Açili- Tabakali Kompozit Kirişlerin Etkileşimli Serbest Titreşimleri

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2008Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2008Basit mesnetli tabakalı kompozit kirişlerin düzlem-dışı eğilme ve burulma etkileşimli serbest titreşimleri ANSYS 10.0 yazılımı kullanılarak sonlu eleman yöntemiyle incelenmiştir. Dönme ataleti ve kayma deformasyonu etkileri analizde dikkate alınmıştır. Simetrik dizilişe sahip hem çapraz- hem de açılı-tabakalı kirişlere ait sayısal uygulamalar yapılmış, doğal frekanslar ve mod yapıları analiz edilmiştir. Tabaka açısı, malzeme elastisite modülü, boy/kalınlık ve genişlik/kalınlık oranları ile tabaka sayısının doğal frekansa etkileri parametrik olarak araştırılmıştır. Sonlu eleman modelinin geçerliliği, literatürde mevcut değerler ile karşılaştırma yapılarak gösterilmiştir.Coupled out-of-plane and torsional free vibrations of simply-supported laminated composite beams is studied by finite elements method using ANSYS 10.0 software. The rotary inertia and shear deformation effects have been included in the analysis. Numerical applications are carried out for symmetric cross- and angle-ply beams; natural frequencies and mode shapes are analyzed. Parametric studies are performed to study the effects of layer angle, material orthotropicity, length/thickness and width/thickness ratios and layer number on natural frequencies. The validity of the finite element model is shown by comparing the results with those available in the literature

Main Problems in the School Administration and Solutions Proposed: A Qualitative Study

This study aims to determine the main problems faced in administration by the school principals of kindergartens, primary, secondary and high schools, stemming from teachers, school personnel other than teachers, students, parents, etc.; and to identify the solutions proposed for these main problems. The research is a qualitative research modeled in the screening model and case study. Study group of the research consisted of 12 school principals selected through maximum sampling method, and working in state kindergartens, primary, secondary and high schools in the central district of Siirt in 2017-2018 school year. Research data was analysed through descriptive analysis and content analysis by utilizing semi-structured interview method. According to the research results, it was found out that school principals face with problems such as “teachers’ disregard and negligence of their tasks, low qualifications of the school personnel other than teachers, disobedience to school and classroom rules by the students, accusatory and biased attitudes of the parents, under-allocation of funds to schools”. Moreover, it was determined that in relation to these main problems, school principals suggested to “introduce a payment system based on performance and career, to outsource cleaning services, to make home visits to meet the parents, to organize guidance and training activities for parents, and to allocate a separate budget for each school”, as solutions proposed

Yaprak Yaylarda Sonlu Elemanlar Yöntemi İle Yorulma Analizi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Bu çalışmada yeni yaprak yay tasarımları için mümkün olan en az sayıda prototipin üretilmesini ve seri üretime en kısa sürede geçilebilmesini sağlayacak bir yöntem geliştirilmesi amaçlanmıştır. Yorulma ömrünü belirlemeden önce parabolik yaprak yay tasarımına ve yorulma ömrüne etki eden faktörler incelenmiştir. Tek katlı bir parabolik yaprak yay için sonlu elemanlar (SE) modeli üzerinde gerilme ve yorulma analizleri Ansys Workbench 14.5 ve Ansys nCode Design Life 14.5 programları ile gerçekleştirilmiştir. Elde edilen SE analizi sonuçları, deneysel değerler ile karşılaştırılmış ve maksimum %9.08’lik fark ile doğrulanmıştır. Yapılan yorulma ömrü belirleme çalışması, ağır ve hafif ticari araçlarda kullanılan yaprak yayların tasarımlarında, prototip üretimi sonrasında, parça üzerinde uzun süren denemeler yapmaya gerek kalmaksızın, yorulma ömrünün SE analizleri ile belirlenmesinin mümkün olduğunu göstermiştir.In this study, the main goal is to develop a new method to minimize the number of prototypes and the testing period required to start mass production. The parameters affecting the fatigue life and the criteria for parabolic leaf spring design have been investigated before the determination of fatigue life of leaf springs. Stress and fatigue life analysis of the finite element model of the parabolic leaf spring have been performed using Ansys Workbench 14.5 and Ansys nCode Design Life 14.5 codes. The results of the finite element analysis are compared with the experimental results and verified with a maximum 9.8% difference. The present study proved that it is possible to determine the fatigue life of leaf springs used in heavy and light commercial vehicles by the finite element analysis without long test periods after the production of prototypes

Üç Serbestlik Dereceli Kütle-Yay Sisteminin Serbest Titreşim Analizi İçin Taylor Matris Yaklaşımı

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Üç serbestlik dereceli bir kütle-yay problemi ele alınmıştır. Kütle-yay sisteminin hareketini tanımlayan diferansiyel denklem sistemi Taylor matris yöntemi ile çözülmüştür. Her bir kütlenin hareketini veren fonksiyon elde edilmiştir. Elde edilen Taylor matris çözümleri tam çözümlerle karşılaştırılarak uyumlu oldukları gösterilmiştir.Three degree of freedom system is considered as mass-spring system. The Taylor matrix method is employed to solve the differential equations systems of motion of the mass-spring system. The solution functions are obtained for each mass. The Taylor polynomial matrix solutions are compared with the exact solution and it is shown that the results from both methods are in good agreement

Eksenel Yüklemeye Maruz Değişken Kesitli Euler-Bernoulli Kirişinin Üstel Matris Yöntemi İle Enine Titreşim Analizi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Bu çalışmada eksenel yüklemeye maruz kirişin enine titreşim denklemi olan yüksek mertebeden değişken katsayılı lineer diferansiyel denklemin üstel matris yöntemiyle çözümü sunulmuştur. Bu yöntemde temel olarak, üstel fonksiyonlar ve türevlerinin matris formları inşa edilmiş ve matris formlarının toplamlarına sıralama noktaları uygulanarak temel matris denklemi elde edilmiştir. Elde edilen bu matris denklemi cebirsel lineer denklem sistemine karşılık gelmektedir. Bu denklem sistemi temel matris işlemleri ile çözülmüştür. Elde edilen yaklaşık çözümlerin artık ve mutlak hataları incelenmiştir. Yöntemin etkinliğini gösterebilmek için birkaç sayısal problem örnek olarak ele alınmıştır.This paper presents an exponential matrix method for the solution of transverse vibration of a beam subjected to an axial compressive load of , governed by the high order linear differential equation with variable coefficients. The problem is considered with the mixed conditions. In this method, the matrix forms of exponential functions and their derivatives are constructed basically and then the fundamental matrix equation is formed by the use of collocation points. This matrix equation corresponds to a system of linear algebraic equations and it is solved by basic matrix operations. The residual and absolute errors of the approximate solution are investigated. Some numerical examples are given to demonstrate the efficiency of the method

SCHOOL ADMINISTRATORS’ AND TEACHERS’ VIEWS ABOUT THE USE OF SOCIAL MEDIA AT SCHOOLS AS A NEW PLATFORM IN ORGANIZATIONAL COMMUNICATION

This research aimed to evaluate the school administrators’ and teachers’ views about the use of social media at schools as a new platform in organizational communication. Phenomenology, a qualitative research model, was used in the research. A total of 17 participants who were included in the research (school administrators and teachers) were selected by using the purposive sampling methods that were well-suited to the qualitative research studies, namely, the “maximum variation sampling method” and the “criterion sampling method”. Participants’ views were received via semi-structured and in-depth interviews. The research data were analyzed by using the NVivo 12.0 software. The inductive descriptive analysis, content analysis, and the constant comparison technique were utilized in the interpretation of interview texts. In this context, the participants’ views were grouped under the themes of “views about the definition of social media”, “views about whether the use of social media at schools is necessary”, “views about the purpose of using social media at schools”, “views about the likely effects of using social media at schools”, and “views about recommending the use of social media at schools”. In the research, the participants stated that they viewed social media as a communication tool, the use of social media at schools was necessary, social media platforms could be used for education & instruction and giving (sharing) information, social media could have positive effects besides negative effects, and certain societal, technical, and legal measures should be taken to assure that the social media was used effectively. To ensure the professional use of social media at schools, it is recommended that educators undergo professional development.  Article visualizations

Lomber disk hernisi nedeniyle düşük ayak gelişen hastalarda semptomların başlangıcından ameliyata kadar geçen sürenin prognoza etkisi]

Aim: The aim of this study was to evaluate the effect of the duration from foot drop development to nerve decompression on the rate and degree of recovery in foot drop clinic. Material and Methods: We retrospectively reviewed 30 consecutive patients who had undergone microdiscectomy for foot drop clinic (ankle dorsiflexion 0/5 paresis) between April 2014 and February 2019. Patients were divided into three groups according to the time from foot drop development to surgery, as 1 week. Kruskal-Wallis and Bonferroni corrected Mann Whitney U test were used to evaluate the rate and degree of recovery of ankle dorsiflexion muscle strength between groups. Results: In this study, 30 patients (18 females and 12 males) who underwent surgery for foot drop were evaluated. Mean age at the time of surgery was 46.5±13.5 (range, 18-72) years. Postoperative ankle dorsiflexion strength was 4.2±1.6 (range, 0-5) in 1 week group. Postoperative muscle strength improvement level of 1 week group (p=0.002). There was no statistically significant difference between 72 hours-1 week group and >1 week group (p=0.427). Conclusion: In foot drop clinic, the duration from onset of symptoms to surgical decompression was a statistically significant predictor of postoperative recovery rates. © 2019, Duzce University Medical School. All rights reserved.Medical Research Council, MRC: Table1A total of consecutive thirty patients, who had undergone microdiscectomy due to foot drop clinic (ADF 0/5 paresis) by the same surgical team in two different state hospitals between April 2014 and February 2019, were retrospectively reviewed. Clinical records, radiological imaging reports and surgical reports were reviewed. Data on patient demographics and clinical features, the time elapsed between the development of foot drop and surgery, duration of surgery, and muscle strength of ADF in the early post-operative period were reached. The evaluation of muscle strength of the ADF was carried out by the assessment of the tibialis anterior muscle in accordance with the muscle strength scale of Medical Research Council (Table1). Comorbidities, including diabetes mellitus (DM), smokers, coronary artery disease, chronic obstructive pulmonary disease (COPD) and hypertension were ascertained from the medical records. All procedures carried out in studies including human participants were conducted in compliance with the ethical standards of institutional and/or national research committee, the Helsinki Declaration and its amendments or comparable ethical standards. Ethical approval for the study was obtained from the institutional review board of Namık Kemal University (01.08.2019, 2019/21). Informed and written consent was obtained from all patients. The patients were divided into three groups as regards the time elapsed from the development of foot drop to surgery, as 1 week. Statistical Analysis Normality assumption for continuous data were examined by Shapiro-Wilk test. The differences between the groups were analyzed by Kruskal-Wallis test followed by Mann Whitney U test with Bonferroni correction, since variables not showing normal distribution. Descriptive statistics given as mean±standard deviation and median (minimum-maximum). Categorical data were analyzed with Fisher-Freeman-Halton test and summarized as frequency and percentage. All statistical analyses were performed using MedCalc v.12.7.7 (MedCalc Software, Ostend, Belgium), and p<0.05 was considered statistically significant

The Roles of Perceived Social Support, Coping, and Loneliness in Predicting Internet Addiction in Adolescents

The current research aims to examine the roles of perceived social support, coping, and loneliness when predicting the Internet addiction in adolescents. The research participants included 300 high school students, with an average age of 16.49 and SD=1.27, attending schools in a city in Southeastern Anatolian Region during 2015-2016 academic years. Participant adolescents included 180 females (60%) and 120 males (40%). Data collection was conducted through Short Form of Young’s Internet Addiction Test, Revised Form of Multi-Dimensional Perceived Social Support Scale, Coping Scale for Children and Youth, and the UCLA Loneliness Scale – Short-Form. Descriptive statistics, Pearson Correlation Coefficient, and Multiple Linear Regression Analysis were used to analyze the research data. Research findings showed that perceived social support from significant other support, loneliness, and cognitive avoidance and problem solving among coping strategies significantly predicted Internet addiction. Family support and friend support as sub-dimensions of perceived social support and assistance seeking and behavioral avoidance among coping strategies were not found to predict Internet addiction. Research findings were discussed based on the relevant literature, interpreted, and suggestions for researchers were put forward. Keywords: Internet addiction, perceived social support, coping strategies, loneliness, adolescent

EVALUATION OF VIDEO CHALLENGE SYSTEM IN VOLLEYBALL FROM THE POINTS OF CLASSIFICATION REFEREES

In order to prevent referee mistakes in volleyball, Video Challenge System has been used in our country since 2015. The aim of the research is to examine the functionality of this system from the perspective of Classification Volleyball Referees assigned in the Efeler and Sultans Leagues and to offer opinions and suggestions for the development of the system. The research was carried out with the screening model, which is one of the quantitative research methods. Participants were reached with a 20-question Video Challenge System Questionnaire, which was developed for the purpose of collecting data in the research. The sample of the research consists of a total of 67 people who participated in the interim seminar with the participation of A and AB Classification volleyball referees in Ankara on 18 December 2021, with a physical questionnaire. The analysis of the data was made with the SPSS 26.0 program and the data on demographic variables were analyzed according to frequency analysis. When the findings of the study are examined; 91.1% of A and AB Classification Volleyball Referees said that the Video Challenge System contributed positively to the course of the match, 98.5% found the VCS applied in our country useful, 94% said that the referees were more comfortable in the matches played with VCS. observed that, 98.6% of them stated that VCS minimized the wrong decisions in numbers that could affect the match or set result, 91.1% stated that VCS directly positively affected the set or match result in competitions with high game quality, and 97%. They stated that the VCS facilitated the work of the referees in terms of making decisions, especially in the most difficult moments of the match. As a result, it has been concluded that the satisfaction of the referees who referee the Efeler and Sultans League matches, which are the highest level leagues of the Turkish Volleyball Federation, with the Video Challenge System is at a very high level. With the results obtained, it is thought that the Video Challenge System has a positive contribution to the fair conclusion of the matches and the surrender of the right.  Article visualizations