Implementation of new and classical set covering based algorithms for solving the absolute p-center problem

Ankara : The Department of Industrial Engineering and the Institute of Engineering and Science of Bilkent University, 2011.Thesis (Master's) -- Bilkent University, 2011.Includes bibliographical references leaves 80-82.The p-center problem is a model of locating p facilities on a network in order to minimize the maximum coverage distance between each vertex and its closest facility. The main application areas of p-center problem are emergency service locations such as fire and police stations, hospitals and ambulance services. If the p facilities can be located anywhere on a network including vertices and interior points of edges, the resulting problem is referred to as the absolute p-center problem and if they are restricted to vertex locations, it is referred to as the vertex-restricted problem. The absolute p-center problem is considerably more complicated to solve than the vertex-restricted version. In the literature, most of the computational analysis and new algorithm developments are performed through the vertex restricted case of the p-center problem. The absolute p-center problem has received much less attention in the literature. In this thesis, our focus is on the absolute p-center problem based on an algorithm for the p-center problem proposed by Tansel (2009). Our work is the first one to solve large instances up to 900 vertices on the absolute p-center problem. The algorithm focuses on solving the p-center problem with a finite series of minimum set covering problems, but the set covering problems used in the algorithm are constructed differently compared to the ones traditionally used in the literature. The proposed algorithm is applicable for both absolute and vertex-restricted p-center problems with weighted and unweighted cases.Saç, YiğitM.S

Does the Early and Late Rate of Torque Development, Change in Relation to the Quadriceps Angle?

The rate of torque development (RTD), which determines the force that can be developed in the early phase of muscle contraction (0-200 ms), is very important in terms of tracking explosive strength improvement and preventing knee injuries. The purpose of this study was to investigate the relationship of quadriceps angle which affects the structural alignment of the lower extremity with early (0-100 ms) and late (100-200 ms) rate of torque development of the knee extensor muscles and myoelectrical activity. The study was carried out with 38 well-trained male basketball players (mean age: 22.3±2.5 years). The participants were divided into two groups with normal (10°) values. RTD was measured in concentric/concentric mode at 60, 120 and 180°/s angular velocities in an isokinetic dynamometer. Surface electromyography (sEMG) was used to determine the myoelectrical activity. When RTD0-100 and RTD100-200 were examined, statistically significant difference was observed at 60 and 120°/s (p<0.05). However, no difference was observed at 180°/s. In addition, sEMG data did not have a statistically significant difference between groups. Negative correlation was found between all RTD at 60, 10 and 180°/s with Q angle (180°/s RTD0-100 r= -0.34, 180°/s RTD100-200 r= -0.35, 120°/s RTD0-100 r= -0.40, 120°/s RTD100-200 r= -0.48, 60°/s RTD0-100 r= -0.55, 60°/s RTD100-200 r= -0.59; p<0.05). There was a negative correlation between the structural differences of the lower extremity and the early and late rate of torque development of the knee extensor muscles. Considering the structural variables, it is thought that it is important to improve the rate of torque development with appropriate resistance training in athletes with variables such as abnormal Q angle, and thus knee injuries can be prevented through athletic development

Socio-demographic Characteristics and Sleeping Habits of Children with Suicide Attempt Abstract

Introduction:To compare the sleeping habits of children who attempt suicide with healthy children, to detect disorders, to identify children with risk factors and to take measures to prevent suicide attempts.Methods:Patients who applied to the Pediatric Emergency Service of University of Health Sciences Turkey, Ankara Training and Research Hospital between April 2019 and April 2020 with suicide attempt were included in the study group, and healthy children who had never attempted suicide before were included in the control group. It has been done prospectively and cross-sectionally. The data were analyzed using SPSS 18.0 package program and Microsoft Office Excel 2003 program.Results:The total number of patients participating in our study was 248, 138 (55.6%) of whom had attempted suicide, 110 (44.4%) were from the control group who did not attempt suicide for any other reason. Of the patients in the group who attempted suicide, 102 (73.9%) were female, 36 (26.1%) were male, 67 (60.9%) of the patients in the control group were female, and 43 (39.1%) were male. The median age of the patients in the group who attempted suicide was 16 (minimum: 13, maximum: 18), and the median age of the patients in the control group was 16 (minimum: 12, maximum: 18). Social and physical problems were more common in the group who attempted suicide than in the control group (p=0.001, p=0.004). In the sleep habits questionnaire applied to the patients; the patients in the group who attempted suicide had more problems falling asleep, frequent waking up, and difficulty in waking up compared to the control group (p=0.001, p=0.047 p=0.003). In addition, daytime sleepiness, change in sleep time, listening to music before sleep, and playing with a mobile phone were higher in the group who attempted suicide compared to the control group (p=0.012, p=0.001 p=0.022, p=0.005). In addition, nightmares, sleepwalking, and snoring were more common in the group who attempted suicide (p=0.046).Conclusion:Suicide attempt is an increasing problem in adolescents, it should be ensured that the risk factors are determined well, the awareness of families and physicians is increased and preventive measures should be taken. It is very important to take sleep problems more seriously in this age group and to convey the importance of this to families

Opti-akustik stereo görüntüleme.

In this thesis, opti-acoustic stereo imaging, which is the deployment of two-dimensional (2D) high frequency imaging sonar with the electro-optical camera in calibrated stereo configuration, is studied. Optical cameras give detailed images in clear waters. However, in dark or turbid waters, information coming from electro-optical sensor is insufficient for accurate scene perception. Imaging sonars, also known as acoustic cameras, can provide enhanced target details under these scenarios. To illustrate these visibility conditions, a 2D high frequency imaging sonar simulator as well as an underwater optical image simulator is developed. A computationally efficient algorithm is also proposed for the post-processing of the returned sonar signals. Where optical visibility allows, integration of the sonar and optical images effectively provides binocular stereo vision capability and enables the recovery of three-dimensional (3D) structural information. This requires solving the feature correspondence problem for these completely different sensing modalities. Geometrical interpretation of this problem is examined on the simulated optical and sonar images. Matching the features manually, 3D reconstruction performance of opti-acoustic system is also investigated. In addition, motion estimation from opti-acoustic image sequences is studied. Finally, a method is proposed to improve the degraded optical images with the help of sonar images. First, a nonlinear mapping is found to match local the features in opti-acoustical images. Next, features in the sonar image is mapped to the optical image using the transformation. Performance of the mapping is evaluated for different scene geometries.M.S. - Master of Scienc