Phase Equilibria Studies of the Cu-Fe-O-Si System in Equilibrium with Air and with Metallic Copper

Phase equilibria of the Cu-Fe-O-Si system have been investigated in equilibrium: (1) with air atmosphere at temperatures between 1373?K and 1673?K (1100?°C and 1400?°C) and (2) with metallic copper at temperatures between 1373?K and 1573?K (1100?°C and 1300?°C). High-temperature equilibration/quenching/electron-probe X-ray microanalysis (EPMA) techniques have been used to accurately determine the compositions of the phases in equilibrium in the system. The new experimental results are presented in the form of ??Cu₂O??-??Fe₂O₃??-SiO₂ ternary sections. The relationships between the activity of CuO_0.5(l) and the composition of slag in equilibrium with metallic copper are discussed. The phase equilibria information of the Cu-Fe-O-Si system is of practical importance for industrial copper production processes and for the improvement of the existing thermodynamic database of copper-containing slag systems.     

Modeling Massive RFID Data Sets: A Gateway-Based Movement Graph Approach

Massive Radio Frequency Identification (RFID) data sets are expected to become commonplace in supply chain management systems. Warehousing and mining this data is an essential problem with great potential benefits for inventory management, object tracking, and product procurement processes. Since RFID tags can be used to identify each individual item, enormous amounts of location-tracking data are generated. With such data, object movements can be modeled by movement graphs, where nodes correspond to locations and edges record the history of item transitions between locations. In this study, we develop a movement graph model as a compact representation of RFID data sets. Since spatiotemporal as well as item information can be associated with the objects in such a model, the movement graph can be huge, complex, and multidimensional in nature. We show that such a graph can be better organized around gateway nodes, which serve as bridges connecting different regions of the movement graph. A graph-based object movement cube can be constructed by merging and collapsing nodes and edges according to an application-oriented topological structure. Moreover, we propose an efficient cubing algorithm that performs simultaneous aggregation of both spatiotemporal and item dimensions on a partitioned movement graph, guided by such a topological structure.     

Pretreatment predictors of dropout from cognitive behavioral therapy for PTSD in Iraq and Afghanistan war veterans.

Cognitive–behavioral therapies (CBTs) can be effective treatments for posttraumatic stress disorder (PTSD) but their effectiveness is limited by high rates of premature dropout. Few studies have compared pretreatment characteristics of treatment completers and dropouts, and only one has examined these factors in Operations Iraqi Freedom and Enduring Freedom (OIF/OEF) Veterans. This study analyzed archival clinical data from 117 OEF/OIF Veterans evaluated and treated through a Veterans Affairs PTSD clinic. High numbers dropped out of treatment (68%). Treatment dropouts (n = 79) and completers (n = 38) differed significantly on Minnesota Multiphasic Personality Inventory-2 (MMPI-2) scales, PTSD symptom severity, and age. Regression analyses identified one MMPI-2 scale, TRT (negative treatment indicators), and age as unique but modest predictors of dropout. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Structural optimization of non-linear systems under stochastic excitation

This work concentrates on the structural optimization of a class of non-linear systems with deterministic structural parameters subject to stochastic excitation. The optimization problem is formulated as the minimization of an objective function subject to constraints on the response level. The stochastic response is characterized by its first two statistical moments, which are computed by a statistical equivalent linearization technique. The implicit structural optimization problem is replaced by a sequence of explicit sub-optimization problems. The sub-problems are constructed by using a conservative first-order approximation of the objective and constraint functions. The applicability of the proposed design process is demonstrated in three numerical examples where the methodology is applied to systems with nonlinearity of hardening and hysteretic type. The effects of the nonlinearity on the general performance of the final designs are discussed. At the same time, some engineering implications of the results obtained in this work are addressed.     

Time-Dependent Reliability Analysis of FRP Rehabilitated Pipes

The goal of this paper is to present work that demonstrates the application of probabilistic modeling to evaluate the long-term performance of fiber-reinforced polymer (FRP) rehabilitated piping components. The time-dependent reliability index is evaluated for a fully deteriorated piping component rehabilitated with FRP considering the demands of internal fluid pressure, external soil pressure, and traffic loading. Carbon FRP (CFRP) and glass FRP (GFRP) composites are compared and the influence of material deterioration, fiber volume fraction (FVF), and variation in thickness of the composite are assessed using a first order reliability method and compared to a steel pipe under similar loading. A CFRP rehabilitation scheme having a FVF greater than 40% would be needed to exceed the as-built reliability index of a steel pipe under time-dependent composite deterioration, while no practical GFRP FVF can achieve the performance of steel pipe in the presence of time-dependent composite deterioration. Variations in the coefficient of variation (COV) can adversely affect the safety of both FRP rehabilitation schemes where an increase in COV from 10 to 30% result in decreases in the reliability index by 39.4% for CFRP (40% FVF) and 39.7% for GFRP (40% FVF).     

Investigation of Liquidus Temperatures and Phase Equilibria of Copper Smelting Slags in the FeO-Fe2O3-SiO2-CaO-MgO-Al2O3 System at PO2 10?8?atm

Copper concentrates and fluxes can contain variable levels of SiO₂, CaO, and MgO in addition to main components Cu, Fe, and S. Metal recovery, slag tapping, and furnace wall integrity all are dependent on phase equilibria and other properties of the phases and are functions of slag composition and operational temperature. Optimal control of the slag chemistry in the copper smelting, therefore, is essential for high recovery and productivity; this, in turn, requires detailed knowledge of the slag phase equilibria. The present work provides new phase equilibrium experimental data in the FeO-Fe₂O₃-SiO₂-CaO-MgO-Al₂O₃ system at oxygen partial pressure of 10⁻⁸ atm within the range of temperatures and compositions directly relevant to copper smelting. For the range of conditions relevant to the Kennecott Utah Copper (South Magna, UT) smelting furnace, it was confirmed experimentally that increasing concentrations of MgO or CaO resulted in significant decreases of the tridymite liquidus temperature and in changes in the position of the tridymite liquidus in the direction of higher silica concentration; in contrast, the spinel liquidus temperatures increase significantly with the increase of MgO or CaO. Olivine and clinopyroxene precipitates appeared at high MgO concentrations in the liquid slag. The liquidus temperature in the spinel primary phase field was expressed as a linear function of 1/(wt pctFe/wt pctSiO₂), wt pctCaO, wt pctMgO, and wt pctAl₂O₃. The positions of each of the liquidus points (wt pctFe)/(wt pctSiO₂) at a fixed temperatures in the tridymite primary phase field were expressed as linear functions of wt pctCaO, wt pctMgO, and wt pctAl₂O₃.     

Expectations about counseling in Yucatán, Mexico: Toward a "Mexican psychology."

Conducted a study of client expectations of psychological services in Yucatán, Mexico, under the sponsorship of a grant from the Organization of American States. The Expectations about Counseling–Brief form (EAC-B) questionnaire was translated and administered to 488 subjects across age, sex, and experience with psychological services. Subsequent analyses supported the reliability and robustness of the Spanish EAC-B, with factor structure similar to the EAC-B in English. Some relation was found among age, sex, prior counseling experience, and expectations about counseling. Implications of these data for future research and comparison with U.S. subjects are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)