Harmonic resonance occurs when the network equivalent shunt harmonic capacitive reactance is associated with the network series harmonic inductive reactance. When such resonance occurs, it amplifies harmonic components with frequency close to the resonance point. Solutions used to solve harmonic resonance problems can be divided into two main categories. One is to reduce the content of harmonic components in the network (e.g. by using active or passive harmonic filters, etc.) and the other is to remove the resonance stimulating factor by shifting away the resonance frequency to a non-critical frequency range (e.g. detuning PFC capacitors, redesigning feeder transformers, etc.). Studies show that these techniques are not adequate to solve harmonic resonance problems in power distribution networks which are dynamic by their nature and with complex interconnections. Due to this, solutions in the category one are designed for localised harmonic distortion compensation, while solutions in the category two lack real-time operation feature. Therefore, it was identified that there is a need for real-time harmonic resonance attenuation that is suitable for power distribution networks. In this thesis, a new real-time Harmonic Resonance Attenuation (HRA) technique is proposed. This technique may be used with ordinary shunt harmonic filters to make them behave like a virtual shunt capacitor or inductor. Thus, looking from the harmonic current source side, the filter alters the network harmonic impedance and hence results in harmonic resonance attenuation. In order to implement the HRA technique, fast measurement of system harmonics in real-time is required. Therefore, in this work, a fast individual harmonic extraction (FIHE) technique is developed to enhance the desired real-time operation of the HRA. The proposed FIHE needs only one sixth of the fundamental cycle to extract any individual harmonic component which is faster than other methods currently available. In addition to the speed, the proposed FIHE provides overshoot free, oscillation free and ripple free extraction characteristics. The proposed HRA and FIHE techniques are described in this thesis with detailed analysis to illustrate their operating principles. A series of simulations and experiments are conducted to evaluate their functionality and performance. Results of the evaluation are presented and discussed in this thesis together with details of the experimental HRA model developed to verify the theoretical and simulation results.

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.

Thesis (Ph.D.)--Auburn University, 2005. / (UnM)AAI3201458. Source: Dissertation Abstracts International, Volume: 66-12, Section: B, page: 6759. Director: Vitaly J. Vodyanoy.

This thesis explorers the reasons for power shortage and the level of maintenance implementation in Iraqi power plants, furthermore, it examines the current organisational culture in Iraqi power plants, and its effect on maintenance implementation factors. Currently the active power plant units in Iraq are producing only 54% their designed capacity, which is in turn only supplying 50% of the countries’ demand. Therefore, to try and understand the reasons for this low level of efficiency, this research uses an exploratory sequential mixed method design, starting with semi-structured interviews (qualitative) with nine power plant managers or their representatives, followed by a questionnaire survey (quantitative), receiving 484 responses from the employees of those nine power plants. The reasons for power shortage in Iraq were identified, Furthermore, the level of maintenance implementation in the Iraqi power plants, was examined found to be at a medium level. In terms of organisational culture, not enough attention has been paid in the literature. This lack of research in the area of cultural effect on maintenance implementation was one of the main motivators for this study to answer the following question; to what extent do organizational culture profiles effect maintenance implementation factors in organisations. Structural equation modelling (SEM) technique was used to examine the relationship between organisational culture and maintenance implementation factors. Furthermore, based on the research findings, maintenance improvement framework was developed and detailed plans for implementation were formulated. The framework was built on the basis that improving organisational culture will improve the factors affecting maintenance and these factors will facilitate Total Productive Maintenance (TPM) implementation in Iraqi power plants.

Systematic back analyses of cross sections through landslipped slopes in Barton Clay have been carried out, based on the both published (cross sections) and unpublished (piezometer) data. The results of these support earlier (Barton, 1973) rather than later (Barton and Garvey, 2011) interpretations. Ring shear tests on clay samples from these landslides show braod agreement with the back analyses. Further back analyses on landslide elements at Herne Bay in the London Clay throw additional light on the behaviour of landslides there. The remaining coastal landslide case histories in London Clay are reviewed. The body of case records compiled by James (1970) for infrastructure (railway) cutting failures in London Clay is reviewed, with new back analyses. These show clearly the deficiencies in that set of analyses on which several important papers were based. Further reinterpretation and analysis goes some way to resolving questions arising from the review. It is concluded that the back analysis technique is a useful one, and when applied correctly provides excellent general agreement with equally careful laboratory testing for extracting the shear strength parameters for a week bed forming the bedding-controlled basal shear of a compound landslide is presented and used. The analyses and tests are supported by a review of publoshed residual strength properties for British clays.

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.