Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/15956

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Trafo merkezlerinde manyetik alan maruziyetleri üzerine bir inceleme
(Çankaya Üniversitesi, 2018) Sağdıçoğlu, Umut Çetin
Artan enerji ihtiyacı ile sayıları gün geçtikte artan ve enerji iletim sisteminin kalbi olarak görülen trafo merkezlerinde görev yapan işletme teknisyenleri işleri gereği manyetik alana maruz kalmaktadırlar. Bu çalışmada, Türkiye'nin çeşitli bölgelerinde 31 farklı "154kV/34,5kV" trafo merkezinde manyetik alan ölçümü yapılarak çalışanların iş sağlığı ve güvenliği açısından maruziyetleri değerlendirilmiştir. Ölçümler düşük frekansta ölçüm yapan TENMARS TM-192D Üç Eksenli Manyetik Alan Ölçer cihazı ile çalışanların yaptıkları farklı görevler için bulundukları noktalarda yapılmıştır. Elde edilen sonuçlar ölçüm noktalarına göre kategorize edilmiş olup, ölçüm sırasında trafo merkezindeki anlık yük durumu da göz önüne alınarak trafo merkezleri arasında karşılaştırmalar yapılmıştır. Karşılaştırma sonuçları ile ulusal ve uluslararası düzenlemelerle belirlenen limit değerler ışığında trafo merkezi işletme teknisyenleri için yüksek maruziyet teşkil eden bölgeler tespit edilmiştir. Ölçümler sonucunda en yüksek maruziyet değerinin eski tip trafo merkezlerinin kapalı şalt hücre önlerinde olduğu görülmüş olup buradaki en büyük etkenin sistem ile personel arasındaki kısa mesafe olduğu tespit edilmiştir. Manyetik alan maruziyetinin azaltılması için, gelişen teknolojinin sağladığı imkanlar dahilinde işletme teknisyenlerinin tüm işlemleri uzaktan kontrol sistemleri ile kumanda odasından yapması faydalı olacaktır.
Kalker ocaklarında ocak sularının ve delme-patlatma işlemlerinin iş sağlığı ve güvenliği üzerine etkilerinin araştırılması
(Çankaya Üniversitesi, 2018) Aykal, Utku Meriç
Bu çalışma ile kalker sahalarında proses gereği tüm çalışmaların, güvenli sürdürülmesi için gereken proaktif yaklaşımlar incelenmiş, kalker rezervi kazanımı için gereken çalışmalar sırasında meydana gelebilecek risk unsurlarının nasıl en aza indirilebileceği araştırılmıştır. Gerekli saha çalışmaları yapılmış ve iş kazaları, "Mühendislik Metotlar Yöntemi" uygulamaları ile asgariye indirilmeye çalışılmış yani olası iş kazalarına kökten tedbir alınmaya çalışılmıştır.
Effects on Turkish and Libyan kitchen design with reference to cultural food preparation habits
(Çankaya Üniversitesi, 2017) Ammari, Abdulbaset Mohamed Faraj
The kitchen has undergone a dramatic evolution of social change in human history, evolving from enclave to a symbol of isolation; from the original fireplace as the only space for living activity to the modern, rational kitchen where women were isolated. However, today's kitchens have evolved to fit the needs of each family member and thus include a variety of functions. However, today's kitchens have evolved to the point where they accommodate every family member and therefore include multiple functions. This thesis aims to understand the dynamics beneath the evolution of kitchen; referring to cultural in two different countries (Turkey, Libya), in order to find out the problems found in using the kitchens so that better designs may be suggested. The literature shows that a kitchen is an important part in a home, which is a busy area, thus demanding a lot of attention in order to be able to get the needed design requirements. While the findings of the thesis are based on the contemporary urban life, it is not known what the future will hold; so suggestions are made to benefit contemporary needs. The case is the interaction between the household, the kitchen design, and the activities in the kitchen. Interviews have been conducted with household members in the studied cases, as well as with key informants. The main areas of study have been the way food is prepared, cooked and stored in the kitchen, and how these activities take place in a mixed situation of tradition and modernity. People have to negotiate and reinterpret spaces in their kitchens and around them in order to meet their needs. Some of the most important outcomes from this research is not to let modernity be disruptive but rather to allow the change from tradition be gradual. The thesis endeavors to blend the two phenomena of tradition and modernity so as to create a balance in design and end with better functioning kitchens.
Comparative analysis of ottoman palaces in palestine and Turkey with emphasis on ornamentation
(Çankaya Üniversitesi, 2017) Ahmeida, Gebril Farag
Ornamentations are a significant part of architecture as it provides information about the structure, its builders and its users. In this research, a review of the ornamentation development in the Eastern Mediterranean region from the Egyptian, Greek, Roman, and Islamic periods is performed, in addition to the specific types of ornamentations in Palestine and Turkey are researched in detail. In order to perform the analysis, a review of symbolism and ornament classification concepts is carried out. Moreover, ornamentations in the Eastern Mediterranean region are rich with affiliations from different civilizations, cultures and communities. Therefore, it is evident from the study that the ornamentations in Palestine and Turkey have been mainly influenced by similar cultural backgrounds, while preserving each country's nature and community. Cases are selected from Turkey and Palestine in which ornamentations are used in four palaces; TopkapiPalace (Istanbul, Turkey), Nemr Palace, Albdulhadi Palace and Toukan Palace (Nablus, Palestine). The results of the analysis show that the styles, classes, types, geometry, and affiliations of ornamentations in both countries have several similarities, while the main differences are found in color, complexity and the impact of the social status.
User preferences regarding interior vertical gardens
(Çankaya Üniversitesi, 2017) El-Angudi, Ghada M. Mohamed
Landscaping is added to the architectural design of a structure in order to increase its unity with nature, integration with the environment, and create intimate eternal concepts. Therefore, concepts such as vertical gardens and living walls were used since the ancient history in order to add a natural aesthetic effect, as well as providing positive vibe to the external and internal spaces. In this research, the usage and impacts of the vertical garden concepts are examined through a theoretical review of the literature, where many aesthetic, psychological and physiological effects are found. Increasing property value, reducing stress, enhancing indoor air quality and beautifying dull walls, are some of many added values by the vertical gardens. Moreover, the case study of this research evaluated the effects of interior vertical gardens on space users through developing three dimensional computerized models based on an actual space for assessment using environmental appraisal methodologies. The results of the study show that the model with the vertical garden design has a more positive effect on space users, which is significantly different from the model without the vertical garden. Furthermore, using Spearman's rho correlation factors, weak to medium correlations are established between vertical garden perception and gender, age, occupation, cultural background, and space familiarity. In conclusion, there are several positive effects of integrating the vertical garden to the interior space that would encourage architects to integrate them into their designs.
Effect of daylight on students' behavior in libraries
(Çankaya Üniversitesi, 2017) Elibiadi, Mohammed S. R.
Natural lighting is one of the most tried concepts in architecture due to the several psychological and physiological benefits of its utilization on space occupants. Therefore, several studies have shown its positive impacts and superiority to artificial lighting. Moreover, using natural lighting allow owners and facility managers to save up to 40% of the energy used in their buildings. In this research, the perception and impacts of natural lighting is assessed at the library of Çankaya university in Ankara, Turkey. The library has a skylight that allows natural lighting to enter the library during day hours. Through a review of the literature, lighting perception indicators and illuminance measurement techniques are compiled in order to perform a subjective and objective measurement of the lighting in the case space. The library is divided by the researcher into four main zones; A, B, C and D. The findings of the objective illuminance measurement show that cloudy weather reduces the illuminance in the library by 23.1%, while several inadequate illuminances were found in many cases especially in zones A and D. The subjective perception by 120 library users distributed throughout different day periods shows that the lighting perception indicators differed between the different zones. At the end of the study, correlation testing between the subjective perceptions and objective illuminance measurements was performed, which indicated a weak to medium correlation between the two variables.
String stability analysis of Cooperative Adaptive Cruise Control (CACC) with actuator saturation
(Çankaya Üniversitesi, 2017) Bingöl, Hilal
Intelligent transportation systems aim at improving the efficiency and safety of transportation. In dense traffic, vehicles are aggregated to vehicle strings that travel on the same lane, whereby it is desired to maintain a small but safe distance between the vehicles. In the literature, this task is captured by the notion of string stability: fluctuations that are introduced by maneuvers of the leader vehicle should be attenuated by the follower vehicles. The literature provides various methods for achieving string stability under the assumption that the vehicles are modeled as linear systems. In this thesis, we study the case where vehicles are modeled as nonlinear systems and hence face actuation constraints as well as state constraints. Different methods are employed. First, a reachability analysis based on the level-set method determines the states that are reachable under limitations on the engine force of vehicles. It turns out in the thesis that, although the reachability analysis is the proper method to analytically address the problem of saturation, it is computationally not feasible due to the large state space of the vehicle model. As a remedy, a further analysis of the model is carried out for the special case of maneuvers. Based on the realistic assumption that the impulse response of the vehicle following model is positive, several sufficient conditions for the input signal of the leader vehicle are derived in order to preserve string stability under actuator saturation. The first set of condition is concerned with the computation of maximum/minimum input signal that generated based on optimal control solution. These maximum/minimum input signals depend on the initial velocity of the vehicle string. The second set of conditions allows computing suitable input signals of the leader vehicle analytically and is hence highly beneficial in practice. The obtained results are illustrated by extensive simulation experiments.
Trajectory generation for open/close gap maneuvers in vehicle strings
(Çankaya Üniversitesi, 2017) Çankaya, Erkam
Cooperative adaptive cruise control (CACC) is an advanced technology allowing vehicle following at a small inter-vehicle spacing. In its classical usage, CACC assumes that vehicles are arranged in the form of a vehicle string and follow each other at a velocity-dependent distance. Nonetheless, practical driving situations include the case of lane changes, where vehicles can join or leave a vehicle string. In such case, it is required that gaps for joining vehicles are provided or gaps after leaving vehicles are closed in order to ensure safe and efficient driving. This thesis is concerned with gap opening and closing maneuvers in vehicle strings. Introducing a suitable control architecture, gap opening and closing maneuvers can be realized by the generation of feedforward input signals. To this end, the first contribution of the thesis is the development of five methods for the computation and representation of gap opening and closing trajectories that fulfill additional safety and comfort constraints. The first method is based on the solution of an optimal control problem, the second method uses a polynomial trajectory and plant inversion, the third method concatenates three polynomials and uses nonlinear programming to determine the polynomial coefficients, the fourth method uses a high-order polynomial and the fifth method uses concatenated polynomials in order to approximate the optimal control solution. A simulation study shows that the fifth method is particularly useful in practical applications since it computes trajectories that approximate the optimal control solution in real-time. The second contribution of the thesis is the implementation of a vehicle model that realizes CACC and additional feedforward signals in the form of a Matlab S-function.
Automatic scoring approach for Arabic short answers essay questions
(Çankaya Üniversitesi, 2017) Alfalahi, Mohammed Abdulmunem Nsaif
There are different types of questions produced by the students in their exams, such as multiple-choice questions, true/false questions, and essay questions which require free text answers. Evaluation and scoring these types of exams traditionally are an exhausting process that takes from the instructors a lot of efforts, time and activities. In this regard, applying automated approaches to evaluate and score exams are essentially required to reduce time and efforts. Although there are many commercial tools for scoring multiple-choice and true/false questions, yet there is lack of approaches and tools for evaluating and scoring essay questions, especially for the Arabic language. In this research, the aim is to propose an automated scoring approach for short answers to Arabic essay questions. The scoring process is based on the similarity between the student's answer and model answer which is provided by the instructor. Cosine similarity measures will be used for this purpose. Cosine similarity is a heuristic evolutionary measure that has succeeded to solve text to text similarity problems. In this research, we will use the word root for each keyword in the student's answer and the model answer in order to achieve accurate results. The proposed approach will be tested on a data set proposed and will be compared to other approaches.
Improvements in the finite element method and method of moments for the solution of electromagnetic problems
(Çankaya Üniversitesi, 2017) Albayaty, Abdullah Omran Ali
In this thesis, two numerical techniques, the finite element method (FEM) and the method of moments (MoM) are improved for solving electromagnetic boundary value problems governed by differential and integral equations. The FEM is a numerical technique used to solve differential equations. The solution domain is divided into small intervals (elements), and the unknown function is calculated by finding an approximate solution by a truncated series of different shape functions. This approximate solution can be replaced with the original function in the differential equation. As a result, we get the matrix of equations that can be solved to obtain separate solution to the problem. In this thesis, we used the sigmoid function as a novel application, and compare the accuracy of FEM with the sigmoid function against the well-known linear and the step functions. Two examples of electromagnetic problems are presented. It is concluded that the sigmoid function under specific conditions yields the most accurate results. For MoM, this thesis presents a new mathematical algorithm for the solution of electromagnetic problems. This algorithm is schemed to be suitable for solving the singularity that exists in the solution matrix. This adaptive integration algorithm aims to avoid the singularity in the evaluation of the integral so called the Cauchy Principal Value integral. An example electrostatic problem is presented and it is proved that the novel method is accurate.

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