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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Estimation Of Specific Flow Duration Curves Using Basin Characteristics Of Rivers In Eastern Blacksea Basin

Yilmaz, Deniz 01 June 2011 (has links) (PDF)
New and renewable energy resources are important in view of reduction of greenhouse gasses causing climate change and in eliminating of dependence on foreign sources in energy respects. Within this context, hydraulic energy is evaluated as one of the prior energy resources that should be utilized. Turkey has 26 basins and Eastern Black Sea Basin is one of the most feasible basins with a lot of small hydroelectric power plants. In the other hand, there is not enough number of discharge gauging stations in the basin. For that reason, up to now generally area ratio method has been used to estimate the project discharges of small hydroelectric power plants. Objective of this study is to estimate &ldquo / the project discharge&rdquo / which is corresponding to 5 flow percentiles (5%, 10%, 15%, 20%, 25%) depending on topographical, meteorological, hydrologic and soil-land cover parameters through developing a multilinear statistical model for Iyidere Basin as a part of Eastern Black Sea Basin. Perimeter of the basin, the ratio of the basin perimeter to the main stream length of the same basin, the drainage frequency, the mean slope of basin, v the mean annual precipitation and the curve number are the parameters that have been analysed for the multilinear statistical model. Principal Component Analysis, Multiple Regression Analysis and Stepwise Regression Analysis have been run for the data sets. For the computed discharges validation has been done. As a result of validation, it has been seen that the stepwise regression gives much closer discharge values to the observed values than the multiple regression results.
72

A Two-sided Cusum For First-order Integer-valued Autoregressive Processes Of Poisson Counts

Yontay, Petek 01 July 2011 (has links) (PDF)
Count data are often encountered in manufacturing and service industries due to ease of data collection. These counts can be useful in process monitoring to detect shifts of a process from an in-control state to various out-of-control states. It is usually assumed that the observations are independent and identically distributed. However, in practice, observations may be autocorrelated and this may adversely affect the performance of the control charts developed under the assumption of independence. In this thesis, the cumulative sum (CUSUM) control chart for monitoring autocorrelated processes of counts is investigated. To describe the autocorrelation structure of counts, a Poisson integer-valued autoregressive moving average model of order 1, Poisson INAR(1), is employed. Changes in the process mean in both positive and negative directions are taken into account while designing the CUSUM chart. A trivariate Markov Chain approach is utilized for evaluating the performance of the chart.
73

Service Models For Airline Revenue Management Problems

Eroglu, Fatma Esra 01 July 2011 (has links) (PDF)
In this thesis, the seat inventory control problem is studied for airlines from the perspective of a risk-averse decision maker. There are only a few studies in the revenue management literature that consider the risk factor. Most of the studies aim at finding the optimal seat allocations while maximizing the expected revenue and do not take the variability of the revenue and hence a risk measure into account. This study aims to decrease the variance of the revenue by increasing the capacity utilization called load factor in the revenue management literature. In addition to expected revenue, load factor is an important performance measure the state companies work with. For this purpose, two types of models with load factor formulations are proposed. This thesis is the first study in the revenue management literature for the airline industry that uses the load factor formulations in the mathematical models. It is an advantage to work with load factor formulations since the models with load factor formulations are much easier to formulate and solve as compared to other risk sensitive models in the literature. The results of the proposed models are evaluated by using simulation for a sample network under different scenarios. The models we propose allow us to control the variability of revenue by changing the used capacity of the aircraft. This is at the expense of a decrease in the revenue under some scenarios. The models we propose perform satisfactorily under all scenarios and they are strongly recommended to be used especially for the small-scale airline companies and state companies and for scheduling new flights even in large scale, well established airline companies.
74

Matching And Reconstruction Of Line Features From Ultra-high Resolution Stereo Aerial Imagery

Ok, Ali Ozgun 01 September 2011 (has links) (PDF)
In this study, a new approach for the matching and reconstruction of line features from multispectral stereo aerial images is presented. The advantages of the existing multispectral information in aerial images are fully taken into account all over the steps of pre-processing and edge detection. To accurately describe the straight line segments, a principal component analysis technique is adapted. The initial correspondences between the stereo images are generated using a new pair-wise stereo matching approach which involves a total of seven relational constraints. The final line to line correspondences between the stereo images are established in a precise matching stage in which the final line matches are assigned by means of three novel measures and a final similarity voting scheme. Once the line matches are established, the stereo reconstruction of those matches is performed by an innovative reconstruction approach that manipulates the redundancy inherent in line pair-relations. By this way, the reconstruction of the stereo matches that are observed in a nearly-parallel geometry with the epipolar lines can also be performed accurately. The proposed approach is tested over two different urban test sites with various built-up characteristics, and as a result, very successful and promising stereo line matching and reconstruction performances are reached. Besides, the comparison of the results of the proposed approach with the results of one of the state-of-the-art stereo matching approaches proves the superiority and the potential of proposed approach.
75

Effect Of High Hydrostatic Pressure On Quality Factors And Shelf Life Of Atlantic Mackerel (scomber Scombrus) And Red Mullet (mullus Barbatus)

Senturk, Tugce 01 September 2011 (has links) (PDF)
The ability of high hydrostatic pressure (HHP) to extend the shelf life of Atlantic mackerel (Scomber scombrus) and red mullet (Mullus barbatus) was assessed in this study. For that purpose, fillets of both atlantic mackerel and red mullet were subjected to pressure treatments at 200, 300, 400 MPa at 5, 10, 15&deg / C for 5 and 15 minutes. The influence of the treatments on Trimethylamine Nitrogen (TMA-N) level, lipid oxidation stability (Thiobarbituric Acid, TBA level) was investigated as well as color changes. The suitable combinations for Atlantic mackerel were determined as 200 MPa, 15&deg / C for 5 min and 400 MPa, 5&deg / C for 5 min / and for red mullet 200 MPa, 15&deg / C for 5 min. In the second stage, the shelf life of fish samples, which were treated with these conditions and stored at 4&deg / C, were studied by measurement of pH, color, sensorial features (appearance and odor), TMA-N, TBA, Total Volatile Basic Nitrogen (TVB-N), Histamine and Total Mesophilic Aerobic Count (TMAC) formations. Based on these analyses, the unpressurised mackerel samples were acceptable up to only 7 days compared to 17 and 19 days after 200 and 400 MPa treatments / respectively. For red mullet samples pressurization at 200 MPa extended the shelf life an additional 3 days (from 1 week to 10 days). HHP treatment in combination with chilled storage can improve the shelf life and quality of fish.
76

Calibration Of Water Distribution Networks

Ar, Kerem 01 January 2012 (has links) (PDF)
Water distribution network models are used for different purposes. In this study, a model, used for daily operational issues is concerned. Models results should be consistent with actual conditions for sound decisions during operational studies. Adjusting model parameters according to site measurements in order to fit the model to obtain realistic results is known as calibration. Researchers have carried out numerous studies on calibration and developed various methods. In this study, an actual network (N8.3 Pressure Zone, Ankara) has been calibrated by two classical methods developed by Walski (1983) and Bhave (1988). The network parameter calibrated in this study is Hazen-Williams roughness coefficient, C-factor, and other parameters have been lumped in the C-factor. Results of the analysis showed that, C-factors have been found in a wide range.
77

Motivators And Barriers For Green Building Construction Market In Turkey

Gundogan, Handan 01 June 2012 (has links) (PDF)
&lsquo / Green Buildings&rsquo / play an important role to increase the implementation of sustainable strategies in the construction industry. Although there is a process of change within Turkish building environment towards implementation of green strategies nowadays, limited research has been conducted to search the reasons that drive the market and the important barriers that block the green building movement. This thesis is intended to fill this gap in the literature and contribute to the field of knowledge regarding green building construction in Turkey. The results shall benefit both government and market practitioners for the development of green building market. The data presented in this thesis are mainly obtained from a comprehensive questionnaire survey developed based on a deep literature search. The questionnaire is completed by professionals who have an interest on this topic or who have involvement in green building projects. In order to analyze the gathered data, a variety of statistical methods are used and the results are evaluated in detail. In addition to questionnaire survey, six case study green building projects in Turkey are examined and so a snapshot picture of current situation of the green movement is taken. Accordingly, financial considerations, faced difficulties and lessons learned are explained. The findings shall assist in understanding the real needs for green building development in Turkish construction sector. Finally, recommendations for government and researchers are presented so as to steer the construction sector in the direction of sustainability.
78

Shape Analysis Using Contour-based And Region-based Approaches

Ciftci, Gunce 01 January 2004 (has links) (PDF)
The user of an image database often wishes to retrieve all images similar to the one (s)he already has. In this thesis, shape analysis methods for retrieving shape are investigated. Shape analysis methods can be classified in two groups as contour-based and region-based according to the shape information used. In such a classification, curvature scale space (CSS) representation and angular radial transform (ART) are promising methods for shape similarity retrieval respectively. The CSS representation operates by decomposing the shape contour into convex and concave sections. CSS descriptor is extracted by using the curvature zero-crossings behaviour of the shape boundary while smoothing the boundary with Gaussian filter. The ART descriptor decomposes the shape region into a number of orthogonal 2-D basis functions defined on a unit disk. ART descriptor is extracted using the magnitudes of ART coefficients. These methods are implemented for similarity comparison of binary images and the retrieval performances of descriptors for changing number of sampling points of boundary and order of ART coefficients are investigated. The experiments are done using 1000 images from MPEG7 Core Experiments Shape-1. Results show that for different classes of shape, different descriptors are more successful. When the choice of approach depends on the properties of the query shape, similarity retrieval performance increases.
79

Settlement Of Piled Rafts: A Critical Review Of The Case Histories And Calculation Methods

Saglam, Neslihan 01 September 2003 (has links) (PDF)
In this study, settlement analysis of pile groups by hand calculation methods were investigated. Settlement ratio, equivalent pier, and equivalent raft methods were studied. Variations in some of the calculation methods were noted, and some suggestions were given. More than thirty piled raft foundation case histories whose foundation and soil properties known have been found. The settlement of piled foundation in each case was solved by these methods. Results obtained from the calculations following different methods were presented for each case in the form of tables and graphs. Measured and calculated values were compared by making use of graphs and tables. Effect of type of piles was shown. It was tried to find out that which method is suitable under different conditions. In conclusion, suggestions for methods and calculation procedures were given.
80

A National It Strategy For Turkish Construction Industry

Kumas, Nihan 01 May 2004 (has links) (PDF)
In this thesis, a national information technology (IT) strategy applicable to Turkish construction industry for future implementation of IT is developed, advising guidance to current and future stakeholders but also researchers and decision makers to set the right priorities and pre-harmonization for IT in construction. Within this study, the present situation of the industry is discussed, so as to structure today&rsquo / s required industry abilities fulfilling tomorrow&rsquo / s demands and innovative IT solutions. Then, a coherent vision is developed for agile, model-based, knowledge driven Turkish construction industry. Following the analysis of IT trends and opportunities, a national IT strategy framework for the industry is specified. Finally / other country applications are examined to give direction for the developed strategy implementation approach.

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