Risk is an uncertain event which will cause deviation in pre-defined objectives, if it occurs. Risk management aims to identify risks, quantify their impacts and develop strategies to mitigate them to ensure project success. Within the context of risk management studies, risk models are usually designed to simulate the project performance under various scenarios. For risk modeling, the statistical link between the risk events and their consequences is scrutinized. However, this approach has a limitation as the influence of the &ldquo / system&rdquo / is neglected during modeling the relation between risk sources and consequences. The term &ldquo / vulnerability&rdquo / is used to describe internal characteristics of a system which influence this relationship. Management of vulnerabilities in addition to risks is essential for the success of risk management. However, there is no consensus on an appropriate definition of vulnerability parameters and their influence on construction projects. One of the aims of the study is to identify the vulnerability factors for construction projects and to propose a framework which portrays the relationship between risk and vulnerability. For this purpose, a detailed literature survey is performed to define the determinants influencing the level of vulnerability. In addition, case studies were conducted with Turkish contractors to explore the relationships between risk events, project vulnerabilities and project performance. Another objective of the study is to propose a risk and vulnerability ontology which provides a definite vocabulary and machine-comprehensible common understanding of the developed framework. Developed ontology will further be used to form a database for risk and vulnerability management.

By the evolving application of technology in the oil and gas fields, the volume of gathered information through the dynamic surveillance gets enormous. The importance is lying not only in the regular storage and standalone usage of such a big volume of data but also analyzing and integrating them in the light of alternative sources of data in order to turn the data to valuable field performance information. It is aimed to investigate role of the real time (bottom hole temperature gauges and distributed temperature sensor) and dynamic surveillance (PBU/PFO, production test results etc.) data in effectively managing ACG field. The case study has been carried out by integrating various sources of surveillance data (well test, DTS, PBU) with flowing bottomhole temperature and pressure in order to show the response of production wells to offset producers as wells as water injection and gas injection wells. It has been observed that the reservoir pressure change impacts on the GOR trend which in turn is reflected on the FBHT by means of Joule-Thomson effect. Analyzed Azeri filed examples shows that the change in FBHT is dependant on the rate of change of the reservoir pressure as well as the gas saturation. Also, there are several Azeri field examples that confirm the observed FBHT and FBHP fluctuations is the informer of the instability in the lift performance as a result of GOR decline. Along with above study, investigation of correlation between FBHT and measured GOR from an Azeri production well revealed that there exists a flow regime dependent linear correlation between these parameters. Such a correlation is applied in Azeri wells to predict the &lsquo / real-time&rsquo / GOR in the production wells.

Hydropower helps countries meet their energy needs in an economically, environmentally, and socially sustainable way while saving money and increasing energy security and self-reliance. Being one of the fastest developing countries, electricity demand of Turkey has been increasing and is expected to increase in the future. Untapped hydropower potential is among the prospective alternative resources to supply this demand. Developing a hydropower project requires a great deal of expertise in multiple disciplines. RETScreen software developed by CanmetENERGY helps the planners and decision makers to assess the feasibility of renewable energy projects at the pre-feasibility and feasibility stages. This study is an application of RETScreen to assess the feasibility of alternative formulations for Niksar HEPP, a small hydropower project which is under construction in Turkey. Three alternative formulations are generated and their economic performances are evaluated and compared. First, optimum design discharges are calculated and then economical analysis is conducted for various electricity export rates by RETScreen for all the alternatives. This study provides a detailed literature review on hydropower and its economical, social and environmental aspects, and shows how RETScreen can be used in assessing the economical feasibilities of the current formulation for Niksar HEPP and its alternative schemes.

Aspendos Theatre still stands in fairly good condition although it has been constructed about 2200 years ago in Serik village of Antalya, Turkey. Aspendos Theatre is one of the most valuable historical buildings in Turkey. The fact that the structure had overcome numerous possible earthquakes during its lifespan in Antalya and located in second degree earthquake zone, makes the subject an interesting research topic. The earthquake analysis of Aspendos Theatre was conducted using Specification for Structures to be Built in Disaster Areas code and stress levels are investigated using 3D FE modeling. Also, the resonance state of the theatre under sound induced forces due to concerts and exhibitions performed in the theatre has been examined. Structural identification is performed to obtain certain structural characteristics by comparing experimentally measured and analytically obtained natural frequencies. The analytical model is constructed using solid members and the analysis is performed by using SAP2000 software. The elastic modulus of conglomerate used as building blocks in the Theatre is taken as 2350 MPa based on the experimental and analytical studies. The compressive and tensile strength of the theatre wall material is taken as 12 MPa and 1.2 MPa, respectively based on the previous studies conducted on conglomerate. When the maximum stress levels under combined effect of response spectrum and dead load analyses are examined, the level of compressive stress is found to be about 60% of the compressive strength. On the other hand, the tensile stresses developing at upper corners and bottom middle parts of the stage wall and mid-height central location of the exterior wall (on the vicinity of the front door) are calculated to be about 6.6 MPa, which are more than the assumed tensile strength. It has also been calculated that the level of sound that generates tensile failure is about 125 dB as the theatre gets into resonance state.

Change is an inevitable and inherent factor of each construction project which is a result of the nature of industry and the uniqueness of projects. Risky and unstable environment of construction industry usually triggers the potential of occurring changes during a project life cycle. Effective management of changes usually leads to increasing the project success. Change prediction and evaluation is the major step of change management process which enables the project management team to have a clear perspective of probable changes and their impacts on project. An effective prediction should be conducted based on a generic overview of likely causes and impacts of changes on projects / therefore establishing a comprehensive model of &ldquo / Change Causes&rdquo / is imperative in order to facilitate the systematic management of project change. This thesis is based on a literature review on existing investigations and researches on project changes and their causes in construction industry and tries to develop a generic and comprehensive classification of &ldquo / Change Causes&rdquo / , from project design to construction and utilization. The proposed taxonomy is in the form of a hierarchical system to facilitate the application and extension of &ldquo / Change Causes&rdquo / categories. The taxonomy has 3 levels of categories which are identified based on their origin and independent from responsible party of change cause. Since the changes usually occur during the whole project lifecycle, the proposed taxonomy covers all project phases from conception to construction and commissioning. The proposed taxonomy has been validated through a survey among the construction professionals and last revisions have been conducted based on the results of validation phase.

Shallow water flow and lost circulation are frequently encountered problems during drilling top holes of oil, gas or geothermal wells. Plenty of methods have been applied to overcome these problems. Placement of silicate based gel systems is one of the oldest methods to seal such undesired zones. For this study, sodium-silicate based gel system is investigated experimentally. This gel system is deliberately delayed multi-component system mixed as a uniform liquid at the surface but desired to form strong gel where it is placed in the well. The experimentally analyzed system is composed of distilled water, sodium-silicate solution, polymer solution, lost circulation materials, weighting agent and organic initiator. In this study, effect of these components on gel time, gel quality and gel strength at room temperature is investigated as a function of their concentration. To be able to compare gelation time of different compositions, gel time tests were performed by following the developed method in this study. Observation codes were defined to be able to compare the gel qualities of different compositions. For gel time and quality tests, sodium-silicate concentrations from 3.5% to 15% were studied and the concentrations between 7.5% and 10% were found as optimum. Gel time is getting higher as silicate-initiator ratio (SIR) increases for these optimum concentrations. It was also determined that, addition of polymers reduces the gel time and increases the elasticity of the resulting gels. Long term gelation process was investigated by monitoring turbidity (NTU) of the mixtures and plotting NTU versus time curves. Viscosity development curves obtained from rotational viscometer at various constant shear rates indicated reduced gelation times with increasing shear rate. Furthermore, by using modified High-Pressure, High-Temperature filter press cell, it was determined that, addition of lost circulation materials increases the extrusion pressure.

Low resolution (LR) Grid Digital Elevation Models (DEMs) are the inputs of multi frame super resolution (MFSR) algorithm to obtain high resolution (HR) grid DEM. In digital image MFSR, non-redundant information carrying LR image pairs are a necessity. By using the analogy between digital image and grid DEMs, it is proven that, although the LR grid DEMs have a single source, they carry non-redundant information and they can be inputs of MFSR. Quality of grid DEM can be increased by using MFSR techniques. The level of spatial enhancement is directly related to the amount of non-redundant information that the LR grid DEM pairs carry. It is seen that super resolution techniques have potential to increase the accuracy of grid DEMs from a limited sampling.

METU-Online, a distance education tool developed and maintained by Middle East Technical University (METU) Informatics Institute, can be defined as Customer-to-Business-to-Customer (C2B2C) e-business. In this thesis, a new design and improvement of this system based on Customer Relationships Management (CRM) is presented. With this approach a CRM system is designed, an organizational change is recommended, customercentered business processes are improved to a certain extend, a CRM data warehouse is broadly defined and a basic reporting system is designed. The result of a system analysis of METU-Online, methods used in this analysis, and the CRM model and the recommended design are presented.

Scour at bridge piers is considered as a significant safety hazard. Hence, scour countermeasure design plays a critical role to hinder the scour potential at bridges. The selection methodology for a scour countermeasure varies with respect to site conditions, economy, availability of material and river characteristics. The aim of this study is to review the literature on this topic to gather universally accepted design guidelines. A user-friendly computer program is developed for decision-making in various sequential steps of countermeasure design against scouring of bridge piers. Therefore, the program is eventually intended to select the feasible solution based on a grading system which deals with comparative evaluation of soil, hydraulic, construction and application aspects. The program enables an engineer to carry out a rapid countermeasure design through consideration of successive alternatives. A case study is performed to illustrate the use of this program.

A planar single facility location problem, also known as the Fermat&ndash / Weber problem, is to