Formation and Transformation Characteristics of Magnetite (Iron(3)oxygen(4)) Under Different Laboratory and Field Conditions.

Formation and transformation characteristics of different kinds of magnetite were studied extensively in this work. Magnetites containing various amounts of cation deficiencies were characterized using magnetization data, lattice parameters, and Infrared Absorption Spectrophotometry. It is shown that $\alpha$-Fe\sb2O\sb3 nucleates in $\gamma$-Fe\sb2O\sb3 during the oxidation process of magnetite. Relative defect contents of several laboratory synthesized as well as field samples were obtained and correlated to their IR patterns. Stability criteria of magnetite formed under atmospheric conditions were probed into utilizing laboratory fog tests and it was concluded that in wet/dry cyclic testing continuous wetting or wetting in excess of 90% of the cyclic time produces magnetite in the oxide formed on steels, whereas drying in each cycle in excess of about 15% of the cyclic period produces defective magnetite as the dominant iron oxide phase present in the rust. It was concluded that magnetite is not stable in an oxidative environment and it transforms (oxidizes) to defective magnetite or to $\gamma$-Fe\sb2O\sb3, but appeared not to $\gamma$-FeOOH. Thick magnetite electrodes obtained from bridge corrosion products were studied in potentiodynamic polarization experiments. During oxidation magnetite was found to passivate at pH levels of 4.0, 7.0, and 10.0 and passivation breakdown was found to occur at a potential around +1200 mV (SCE). Finally, coating of a steel with a phosphate layer using 50% phosphoric acid was found to result in a reduction of oxidative weight gain by 56% and 16% at 750\sp\circC and 925\sp\circC, respectively, for a 100 hour oxidation. The samples formed scales containing FeO, Fe\sb3O\sb4, and $\alpha$-Fe\sb2O\sb3 in successive layers from the metal side, all of them showing preferred orientation (PO) in the untreated cases, about 70% FeO with (111) PO, about 20% Fe\sb3O\sb4 with (400) and (333) PO\u27s, and about 10% $\alpha$-Fe\sb2O\sb3 with (006) and (10,10) PO\u27s. Presence of a subzone in the spinel region having $\gamma$-Fe\sb2O\sb3, atop Fe\sb3O\sp4, immediately below $\alpha$-Fe\sb2O\sb3, could also be documented. Application of the results obtained to practical situations which would require stabilization of magnetite and prevention of its phase transformation through passivation are outlined

Training Graduate Students in Utilization of Analytical Instruments in a Failure Analysis Course

Department of Engineering Technology at University of North Texas offers a graduate course on failure analysis (MSET 5150) during spring semesters. Partial requirement for the course is for students to submit a term paper based on their collected data related to a term project. Case studies are given to groups of students to work on actual failed components received from area industries. Results of their findings are presented at the end of the semester in both oral presentation form and written term paper form followed the format of a well-established technical papers. Results of such exercises allows graduate students devote skills in using scientific instruments and practice manuscript preparations for publication. This paper presents examples of a case studies done by groups of students who worked on failure analysis of components failed in an oil and gas industry. Students developed skills in utilization of scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS), and Fourier Transform Infrared Spectrophotometry. This exercise has proven highly effective in introducing young engineers to real world problems in oil and gas industry and help them develop skills needed in performing failure analysis and steps involved.Cockrell School of Engineerin

Iranian State Strength & Domestic Terrorism: How Iran Came to be the Cool Spot in a Hotbed of Terrorism

This study focuses examines the relationship between domestic terrorism and state strength within in Iran from 1978 to 2010., and It seeks to understand what the specific factors are that are most influentialimpactful in determining the ebb and flow of terrorism. Despite Iran’s position in a region fraught with terrorism, Iran has experienced very low levels of terrorist activity, and yet the literature focusing on terrorism in Iran is largely absent. In order to gain a better understanding of how the strength of the state impacts domestic terrorism, the this study used utilizes various dimensions of state strength the literature available to find key determinants of state strength highlighted in the literature, including economic data and coercive capacity. In addition, I also consider several alternative explanations of terrorism, such as authoritarianism and historical and/or major event, in the context of Iranian domestic terrorism. as well as key causes of terrorism. The study focused on eight different years in which terrorist activity was high as well as low and then compared economic data, the Freedom House scores, historical and/or major events, and the state’s coercive capacity for each of the years to determine the strength of the state and how it compares to the level of terror activity. The study showsanalysis reveals that the economy, Iranian’s’ confidence in the state, and historical and/or major events are most significant in determining heightened the high levels of terrorism that Iran experienced during this period

The impact of effective factors on the Iranian electricity market in comparison to the Spanish electricity market

Electricity market analysis is important to access strategic market information which can be further employed to pass energy policies. Due to the advantages of privatization, the Iranian government has taken certain fundamental steps in order to construct a competitive market, after passing the pertinent laws in its parliament as to the privatization of the electricity market. This PhD thesis presents a detailed econometric analysis of the Iranian electricity market by means of various approaches of time series analysis. The main idea of this thesis rests on the investigation of the state and degree of competition in the Iranian electricity market using the time series analysis approach. This research explains Iranian electricity market mechanisms with linear and nonlinear time series statistical approaches. Mechanisms that were previously developed in the Spanish electricity market provide an opportunity to employ time series modeling to further compare the two markets as a benchmark. This study examines the two indices-price and load-of these markets via time series analysis. In following, it compares these time series analysis in order to present separate estimation models for each index price and load time series (for each market). Implemented models include: linear models (ARIMA), conditional heteroskedastic models (ARMA-GARCH) and nonlinear models (SETAR and ARMA-TGARCH). To assess the best fitted model, MSE and residual volatility analysis tests were implemented. Assuming the conditional variance of our data, the researcher propose the ARMA-TGARCH model as the best suited model for the Iranian electricity market price, ARMA-GARCH model for Iranian electricity load and also for Spanish electricity price and load. Finally, this research explored the role of load in each market using specific statistical methods such as scatter plots, etc. This study will be quite helpful to establish the state of the Iranian electricity market and how exactly to stimulate its degree of competition. The researcher further suggested that at current state, no significant relationship between price and load in the Iranian electricity market exists. This result led the researcher to examine the impact of other macro and microeconomic factors and indices on the electricity prices in the Iranian market. The most important of these factors have been selected through the study and research of energy markets; the most significant include the Henry Hub Natural Gas Spot Price, Europe Brent Crude Oil Spot Price, the US dollar/Iranian Rial foreign exchange rate, and the Iranian (Tehran) Stock Exchange, specifically the TEPIX. Here, the goal was to survey the potential relationship between these factors and Iranian electricity prices via time series correlation analysis. The researcher also clarified that no significant relationship exists between price and these macro and microeconomic factors in the Iranian electricity market. The researcher also assembled forecast from the best estimates derived from the study models and carry out simulations to develop forecasting models. This short-term forecasting is applied to both Iranian and Spanish electricity prices and their respective loads. These predictions also clearly showed the different patterns between these indices¿price and load¿in the Iranian electricity market. Finally, considering the results obtained through the tests and data analysis which examined the Iranian electricity market, it is concluded that the Iranian electricity market could be still recognized as a non-free/centralized market questioning the claimed policies thus far implemented toward decentralizing and privatizing the Iranian marketNasrazadaniAnalizar el mercado de la electricidad es muy importante para acceder a la información estratégica de dicho mercado que además puede ser empleado para aprobar las políticas energéticas. Debido a las ventajas de la privatización, el gobierno iraní ha tomado ciertas medidas fundamentales para construir un mercado competitivo, después de aprobar las leyes fundamentales en su parlamento que permiten la privatización del mercado eléctrico. Esta tesis doctoral presenta un análisis econométrico detallado del mercado eléctrico iraní, mediante diversos enfoques de análisis de series temporales. La idea principal de esta tesis se basa en la investigación así como el grado de consecución en el mercado eléctrico de Irán utilizando el enfoque de análisis de series temporales. En esta investigación se explican los mecanismos de mercado de la electricidad iraní mediante enfoques de series temporales lineales y no lineales. Los mecanismos que se han desarrollado con anterioridad en el mercado eléctrico español ofrecen la oportunidad de emplear el modelado de series temporales para comparar los dos mercados analizados como punto de referencia.Este estudio examina los dos índices –precio y potencia– de estos mercados mediante series temporales. A continuación, se comparan estas series temporales con el fin de presentar modelos para cada precio y potencia de dichas series temporales. Los modelos implementados incluyen: modelos lineales (ARIMA), modelos heterocedásticos condicionales (ARMA-GARCH) y modelos no lineales (SETAR y ARMA-TGARCH). Para evaluar el mejor modelo ajustado se calcula el error cuadrático medio (ECM) y se implementan los tests que permiten analizar la volatilidad residual. Suponiendo que nuestros datos detectan varianza condicional, la investigadora propone el modelo ARMA-TGARCH como el modelo más apropiado para el precio de mercado de la electricidad de Irán, modelo ARMA-GARCH para la potencia iraní y también para los precios y potencia de la electricidad española. Por último, esta investigación explora el papel de la potencia en cada mercado usando métodos estadísticos específicos, tales como gráficos de dispersión, etc. Este estudio será de gran ayuda para establecer el estado del mercado de la electricidad de Irán y cómo exactamente se puede estimular su grado de competencia. La investigadora sugiere, además, que en el estado actual, no existe una relación significativa entre el precio y la potencia en el mercado eléctrico iraní. Este resultado ha llevado a la investigadora a examinar el impacto de otros factores e índices macro y microeconómicos sobre los precios de la electricidad en el mercado de Irán. Los factores más importante han sido seleccionados a través del estudio y la investigación de los mercados energéticos; los más significativos incluyen el precio “Spot del Henry Hub Natural Gas”, “Precio Spot del Petróleo Brent Europeo”, “Dólar estadounidense / Rial iraní tipo de cambio”, y la Bolsa de Valores (Teherán), en concreto el TEPIX. En este caso, el objetivo ha sido estudiar la posible relación entre estos factores y precios de la electricidad de Irán a través de la correlación de series temporales. La investigadora también ha reunido las predicciones de las mejores estimaciones derivadas de los modelos estudiados y ha llevado a cabo simulaciones para desarrollar modelos de predicción. Finalmente, considerando los resultados obtenidos a través de los testes y análisis de datos que examinó el mercado de la electricidad de Irán, se concluye que el mercado de la electricidad de Irán podría ser aún reconocido como un mercado no libre / centralizado cuestionando las políticas reclamadas hasta ahora implementadas hacia la descentralización y la privatización del mercado iraní

Measurement of the Coefficient of Thermal Expansion of Superconducting Thin Films Using Powder X-Ray Diffraction

The High Density Electronics Center (HiDEC) at the University of Arkansas, Fayetteville is developing the technology for High Temperature Superconductor Multi-Chip Modules (HTSC-MCM\u27s). As part of this work, we are looking at the mechanical properties of HTSC materials. An important mechanical property which influences the mechanical integrity of the hybrid MCMis the coefficient of thermal expansion (CTE) of the HTSC films. As a first step in developing a procedure for the determination of the CTE of HTSC materials, the lattice parameters and the CTE of an alpha-alumina substrate have been determined by powder x-ray diffraction technique. An extension of this technique applicable to HTSC materials is presented

High-Fidelity Conjugate Heat Transfer Simulation of Micro-Channel Heat Exchanger

Article describes how high-fidelity conjugate heat transfer simulations are used to model a micro-channel heat exchanger (MCHE) in a crossflow to study its thermal-hydraulic performance. Three different microchannel geometries, namely circular, triangular, and square with louver-shaped fins, are considered

Comparison of Thermal Effectiveness and Crevice Corrosion Risk of Fin Geometry on All-Aluminum Microchannel Heat Exchangers

Article all-aluminum microchannel heat exchangers have recently gained popularity in the heating, ventilation, and air conditioning industry. Despite their attractive thermal performance design, these heat exchangers make coils used in automotive, commercial, and residential applications prone to crevice corrosion. This study uses high-fidelity conjugate heat transfer simulations to model a micro channel heat exchanger system that includes fins and tubes with crossflow to compare their thermal effectiveness to gain insight into potential crevice corrosion of the MCHE alloy

Comparing Iranian and Spanish Electricity Markets with Nonlinear Time Series

Electricity market analysis is useful for accessing strategic market information in order to set energy policy. According to recent interpretations of the Article 44 of the Iranian Laws, the Iranian electricity market is to become a free market. Mechanisms that were implemented in the Spanish electricity market - a free market - provide a versatile benchmark to employ time series modeling approach to compare Iran and Spain's electricity markets via price and load time series as two main indices. Here, we develop linear (ARMIA), heteroskedastic (ARMA-GARCH), and nonlinear time series models to model the Iranian/Spanish electricity market for price and load time series indices. We further utilize the conditional variance to propose the ARMA-TGARCH model as the best suited model for the Iranian electricity market price. We employ our models and time series analysis to forecast and question the status of the Iranian market structure as a free market. Keywords: Time series, forecasting, elecricity market, Spain, Iran JEL Classifications: C31, Q41, Q4