Hareketli Zımba İle Bastırılan Tabakanın Sürtünmeli Değme Problemi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Bu çalışmada rijit dairesel zımba (panç) ve tabakanın hareketli değme problemi sürtünme etkisi dikkate alınarak incelenmiştir. Yatay ve düşey tekil kuvvetlere maruz bırakılan panç yüzeyde sabit ses altı hızla hareket etmektedir. Sınır şartları ve Fourier integral dönüşümü kullanılarak problem değme uzunluğunun ve değme gerilmesinin bilinmeyen olduğu ikinci tür bir tekil integral denkleme dönüştürülmüştür. Gauss-Jacobi integrasyon formülasyonu kullanılarak tekil integral denklemin sayısal çözümü gerçekleştirilmiştir. Değme uzunluklarına ve değme gerilmelerine ait sayısal sonuçlar verilmiştir. Panç ile tabaka arasındaki değme uzunluğunun bağıl hız ile arttığı, değme gerilmesinin ise azaldığı görülmüştür.In this study frictional moving contact problem for a rigid cylindrical punch and an elastic layer is considered. The punch subjected to concentrated normal and tangential force, and moves steadily with a constant subsonic velocity on the boundary. The problem is reduced to a singular integral equation of the second kind, in which the contact stress and the contact area are the unknowns, and it is treated using Fourier transforms and the boundary conditions for the problem. The numerical solution of the singular integral equation is obtained by using Gauss-Jacobi integration formulas. Numerical results for the contact stress and the contact area are given. The results show that with increasing values of relative moving velocity, contact width between the moving punch and the layer increases whereas contact stress decreases

Multiple in-cycle transshipments with positive delivery times

We study a centralized inventory sharing system of two retailers that are replenished periodically. Between two replenishments, a unit can be transshipped to a stocked-out retailer from the other. It arrives a transshipment time later, during which the stocked-out retailer incurs backorder cost. Without transshipment, backorder cost is incurred until the next replenishment. Since the transshipment time is shorter than the time between two replenishments, transshipments can reduce the backorder cost at the stocked-out retailer and the holding costs at the other retailer. The system is directed by a centralized inventory manager, who minimizes the long-run average cost consisting of replenishment, holding, backorder, and transshipment costs. The transshipment policy is characterized by hold-back inventory levels, which are nonincreasing in the remaining time until the next replenishment. The transshipment policy differs from those in the literature because we allow for multiple transshipments between replenishments, positive transshipment times, and backorder costs. We also discuss the challenges associated with positive replenishment time and develop upper and lower bounds of average cost in this case. Bounds are numerically shown to have an average gap of 1.1%. A heuristic solution is based on the upper bound and differs from the optimal cost by at most this gap. © 2011 Production and Operations Management Society

Winkler Zeminine Oturan Fonksiyonel Derecelendirilmiş Tabakada Değme Problemi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Bu çalışmada, Winkler zeminine oturan fonksiyonel derecelendirilmiş tabakanın sürtünmesiz değme problemi, elastisite teorisi ve Fourier integral dönüşüm tekniği kullanılarak incelenmiştir. Tabakaya rijit dairesel bir panç (zımba) vasıtasıyla normal doğrultuda bir tekil yük etki ettirilmiştir. Tabakanın elastisite modülünün kalınlık boyunca, üstel bir fonksiyona bağlı olarak, değiştiği kabul edilirken Poisson oranı sabit alınmıştır. Sınır şartları ve Fourier integral dönüşümü kullanılarak problem bir tekil integral denkleme dönüştürülmüştür. Gauss-Chebyshev integrasyon formülasyonu kullanılarak tekil integral denklemin sayısal çözümü gerçekleştirilmiştir. Tabakanın kalınlık boyunca elastisite modülünü belirleyen (γ) katsayısının ve zemin elastik yay katsayısının )( wk değme uzunlukları ve değme gerilmeleri üzerindeki etkileri incelenmiştir.In this study, the frictionless contact problem for a functionally graded layer on a Winkler foundation is considered in the framework of the theory of elasticity and the Fourier integral transform technique. The layer is indented by a rigid cylindrical punch that applies a concentrated load in the normal direction. The elasticity modulus is assumed to vary exponentially through the thickness of the layer and Poisson’s ratio is taken as constant. The problem is reduced to a singular integral equation with the use of Fourier integral transform technique and the boundary conditions. The numerical solution of the problem is executed by using Gauss-Chebyshev integration formulas. The effect of the material nonhomogeneity parameter (γ) and stiffness of the Winkler foundation ( wk ) on the contact area and the contact stress are investigated

Poverty and Social Psychology: The Importance of Integrative Manner

As one of the most important social problems in the world, poverty has been studied by various disciplines. Although poverty is a basic subject of economics, it has also become one of the prominent research fields of social sciences in recent years. Poverty also relates to many psychological processes and mechanisms just as in the other social problems in the world. It is assumed that the social-psychological approach to poverty may contribute to establishing different road maps in combating poverty. Therefore this study aims at contributing to poverty reduction efforts from the social-psychological point of view by providing an integrative review of the social psychological correlates of poverty based on the empirical findings. Also, by including arguments such as social identity, migration, ideology and social context in poverty studies to be conducted with a social psychological perspective, a contribution can be made to poverty reduction with multidimensional research methods

Nursing Students’ Attitudes About Complementary and Alternative Medicine Methods: A Cross Sectional Study

Objective: In this study, it was aimed to determine nursing students’ attitudes towards complementary and alternative treatment methods Material and methods: A descriptive and cross-sectional study was carried out in the health sciences faculty of a university between February-March 2018. The sample consisted of first and fourth year students of nursing (n:197). The “Descriptive Information Form” and Holistic Complementary and Alternative Medicine Questionnaire (HCAMQ) were used to collect the data. Results: In data analysis, descriptive statistics, student's t test and chi-square test were used. The mean scores the first and fourth year nursing students obtained from the overall HCAMQ were 32.69 ± 5.42 and 30.82 ± 5.84 respectively. There was a statistically significant difference between the first and fourth year nursing students in terms of the mean scores they obtained from the HCAMQ (p lt; 0.05). There was no statistically significant difference between the first and fourth year students in terms of their mean scores for the CAM and HBB sub-dimensions (p gt;0.05). Conclusions: The results of the study demonstrated that the participating nursing students displayed positive attitudes towards the methods of complementary and alternative medicine at a moderate level. Their being knowledgeable about CAM methods is important. In order for nurses to be primarily responsible for patient care and to provide care holistically, their being knowledgeable about CAM methods, and informing their patients about the CAM. Therefore, we recommended that the undergraduate nursing curriculum should also include information about CAM, and students should be provided with educational opportunities about different methods

Sosyal Medyada Müslüman Kimlik Algısı: İslami Fenomenler ve Twitter Örneği

Bu çalışmada Türkiye’de yaşayan, kendisini dindar (Müslüman) olarak tarifleyen ve sosyal medyada “İslami fenomen” olarak görülen/konuşulan insanların; “Müslüman olmanın ve İslami yaşam tarzının” anlamının söylemlerindeki inşası incelenmektedir. Başka bir deyişle; İslami fenomenlerin Müslüman kimliğe ve İslami yaşam tarzına dair görüşlerini belirtirken hangi dilsel kaynakları (açıklayıcı repertuarlar) kullandıkları Eleştirel Söylemsel Psikoloji yaklaşımı ile ele alınmaktadır. Araştırmanın verileri farklı söylem repertuarlarına ulaşma fırsatı veren ve Türkiye’de kullanıcı sayısı oldukça yüksek olan Twitter üzerinden toplanmıştır. Belirlenen 5 İslami fenomenin (Cübbeli Ahmet Hoca -164 bin takipçi, Caner Taslaman - 186 bin takipçi, Said Ercan -645 bin takipçi, Nihat Hatipoğlu - 487 bin takipçi, At gözlüklü /kendine laik -153 bin takipçi) 2012-2018 yılları arasındaki tüm tivitleri incelenmiştir. Alıntılar Eleştirel Söylemsel Psikolojinin analitik kavramlarından biri olan açıklayıcı repertuarlar çerçevesinde analiz edilmiştir. Analiz sonucunda “doğru İslam” ve “öteki’ne karşı birlik olması gereken İslam” repertuarı olmak üzere iki temel açıklayıcı repertuar ortaya çıkmıştır. Doğru İslam repertuarı; İslamiyet’e uygunluk açısından dindar kesimin davranışı ve taşıdığı değerlere vurgu yapmaktadır. Öteki’ne karşı birlik olması gereken İslam repertuarında ise; Müslüman kimliğinin ya da İslamiyet’e inananların üst bir kimlik olarak kurgulandığı görülmektedir

Comparison of carbon sequestration and soil/litter characteristics in black pine and maritime pine afforestation areas in the Western Black Sea Region

Land use and land use change can positively or negatively affect carbon and nutrient stocks in ecosystems. This study was carried out to determine the effects of afforestation with black pine and maritime pine species on carbon stocks and soil and litter characteristics. The study was conducted on afforestation areas and adjacent bare lands in Bartın-Ulus county, located in the Western Black Sea Region of Turkey. Three sample plots of 20×20 m were taken from each land use and the diameter at breast height and tree heights in these sample plots were measured Using the diameter and height values and the biomass equations and carbon ratios developed for the relevant tree species, the tree biomass and carbon stock per unit area were calculated. Then, disturbed and undisturbed soil samples and litter samples were taken from 0-10, 10-20 and 20-30 cm depth intervals at three points in each sample plot. The physical and chemical properties of the soil and litter samples were determined in the laboratory and measurements in the sample plots were converted to a unit area. The data were evaluated using independent sample t-tests and analysis of variance. The results showed that afforestation significantly changed N, S, P, Fe, Zn, and Cu concentrations in the soil; and C, S, Mn, and Zn concentrations in black pine and maritime pine forest floor were different. Besides, the ecosystem carbon (C) stocks differed significantly with forest land use type; black pine plantations, maritime pine plantations and bare land accumulated 148 t C ha-1, 89 t C ha-1 and 27 t C ha-1, respectively. Thus, we suggest that priority should be given to black pine in afforestation of the region and in other ecosystems with similar climates. The results of the research can be used in species selection for afforestation studies in terms of reducing the impact of global climate change

Sliding contact problems involving inhomogeneous materials comprising a coating-transition layer-substrate and a rigid punch

This paper proposes a semi-analytical model for the two-dimensional contact problem involving a multi-layered elastic solid loaded normally and tangentially by a rigid punch. The solid is comprised of a homogeneous coating and substrate joined together by a graded elastic transition layer whose material properties exhibit an exponential dependence on the vertical coordinate. By applying the Fourier transform to the governing boundary value problem, we formulate analytic expressions for the stresses and displacements induced by the application of line forces acting both normally and tangentially at the origin. The superposition principle is then used to generalise these expressions to the case of distributed normal and tangential tractions acting on the solid surface. A pair of coupled integral equations are further derived for the parabolic stamp problem which are easily solved using collocation methods. The primary aim of this paper is to provide insight into the likely behaviour of graded materials under the combined effects of surface pressure and shear stress. In this study, the assumption of Coulomb friction is invoked and the effects of material gradation, coating/interlayer thickness and friction coefficient upon the contact footprint and sub-surface stress field are investigated in great detail. The results we obtain suggest that the thickness of the transition layer as well as the combined thickness of the coating and transition layer have a significant effect on the maximum sub-surface stress attained through contact. This indicates that small changes in the composition of the coating can lead to significant differences in material behaviour. We additionally find that an increase in the amount of friction present in the contact can cause dramatic changes in the pattern of the stress field and can give rise to a much larger maximum stress. This effect can be offset somewhat under certain conditions by changing the thickness of the transition layer. To the best of the authors belief, this work represents the first attempt made to characterise the effects of friction on the sub-surface stress field within a graded elastic material

Evaluation of intraocular pressure and retinal nerve fiber layer thickness in patients with Helicobacter pylori

Objectives: High prevalence of Helicobacter pylori (HP) in the glaucoma patients was shown in recent studies. In our prospective study we aimed to compare the intraocular pressure (IOP) and the retinal nerve fiber layer thickness (RNFLT) in patients with HP positive and negative. Methods: In 91 patients with gastritis HP was investigated by urea breath test (UBT) and biopsy sample culture Following the full ophthalmologic examination the patients’ IOP was measured by Goldmann applanation tonometry and RNFLT was measured by spectral optic coherence tomography. The patients' demographic and clinical characteristics were compared with the χ² test for categorical variables and with the Mann Whitney U test for continuous variables. Results: Of the 90 patients who meet the including criteria, HP was detected in 74 patients (27 male, 47 female) positive, and in 16 patients (7 male, 9 female) negative. Median (minimum-maximum) age values were 46 (18-79) in HP positive group and 51 (18-67) in HP negative group. One hundred forty seven eyes in 74 HP positive patients and 31 eyes in 16 HP negative patients included in the study. Median IOP values were determined 14 (7-21) mmHg in HP positive group and 14 (8-18) mmHg in HP negative group. The measurements of RNFLT in superior, temporal, inferior and nasal quadrants found to be respectively 122(98-165), 68(50-101), 135(93-188), 79(51-120) micron in HP positive group and 120(94-161), 67(43-104), 129(94-166), 76(50-97) micron in HP negative group. No statistically significant difference was found when compared IOP and RNFLT measurements between the two groups (p<0.05). Conclusion: In this study found that the IOP and RNFLT measurements of HP positive group was not show statistically significant difference compared with HP negative group. In a large case series, randomized, case-controlled, histologic and serologic studies should be done to show the relationship between HP and glaucoma