Circuit analysis tools for evaluating separation efficiency of dense medium separators

In order to evaluate the relative separation efficiency among various circuits, a modified circuit analysis tools has been developed and applied to some circuits based upon dense medium separation. The results indicated that this circuit analysis method could predict separation efficiency of different circuit configuration without using washability data.;Based on the selective function for one stage separation, the selective functions for multi-stage circuit configurations were derived, and used to simulate the various circuit configurations. The simulation results demonstrated that some circuit configurations can improve the separation efficiency.;In-plant data for two-stage dense medium cylindrical and conical cyclone circuits without recirculation were studied. The results show that these circuits not only improve the separation efficiencies, but also the qualities of the product by reduction of misplaced materials. The relative separation efficiencies are closed to the calculated value of 1.17 by circuit analysis tool

Testing Institutional Arrangements Via Agent-Based Modeling: A U.S. Electricity Market Example

Many critical goods and services in modern-day economies are produced and distributed through complex institutional arrangements. Agent-based computational economics (ACE) modeling tools are capable of handling this degree of complexity. In concrete support of this claim, this study presents an ACE test bed designed to permit the exploratory study of restructured U.S. wholesale power markets with transmission grid congestion managed by locational marginal prices (LMPs). Illustrative findings are presented showing how spatial LMP cross-correlation patterns vary systematically in response to changes in the price responsiveness of wholesale power demand when wholesale power sellers have learning capabilities. These findings highlight several distinctive features of ACE modeling: namely, an emphasis on process rather than on equilibrium; an ability to capture complicated structural, institutional, and behavioral real-world aspects (micro-validation); and an ability to study the effects of changes in these aspects on spatial and temporal outcome distributions.Institutional Design; agent-based computational economics; U.S. Electricity Market; Locational marginal pricing; Spatial Cross-Correlations; AMES Test Bed

Structures, intermolecular rotation barriers, and thermodynamic properties of chlorinated methanols and chlorinated methyl hydroperoxides

Thermochemical property data on chlorinated methanols and methyl hydroperoxides are important in oxidation, combustion and atmospheric photochemistry of chlorocarbons, Enthalpy, entropy, and heat capacities are determined for three chlorinated methanols and three chlorinated methyl hydroperoxides using density frnctional, B3LYP/6-31G(d,p), B3LYP/6-311+G(3df,2p), ab initio QCISD(T)/6-31G(d,p) and the composite CBSQ/B3LYP/6-31G(d,p) calculation methods. Molecular structures and vibration frequencies are determined at the B3LYP/6-31G(d,p) density functional calculation level. Vibration frequencies are scaled for zero point energies and for thermal corrections. ΔH°f 298 are determined at each calculation level using the ΔHrxn,298 with known enthalpies of other reactants and products in each of five different reactions. S°298 and Cp(T) contributions from vibrations, translations, and external rotations are calculated using the rigid-rotor-harmonic-oscillator approximation based on the vibration frequencies and structures obtained from the density functional studies. Potential barriers for internal rotations are calculated at B3LYP/6-3 1G(d,p) level. Groups for use in Benson type additivity estimations are determined for the carbon with oxygen and chlorine(s). Enthalpy values from the isodesmic reaction show good agreement at all theory levels, suggesting effective cancellation of errors for these two series of molecules

Thermochemistry and kinetics in pyrolysis and oxidation reaction of oxygenate chlorocarbons, neopentane, and ortho-xylene

Thermochemical properties of chlorinated alcohols, chlorinated hydroperoxides and corresponding alkoxy, hydroxy alkyl radicals, peroxy and hydroperoxy alkyl radicals are determined by ab initlo and density functional calculations for modeling and optimization of complex chemical processes for combustion or incineration of chlorinated hydrocarbons. The entropy and heat capacities from vibrational, translational, and external rotational contributions are calculated by statistical mechanics, and the hindered rotational contributions to S°298 and Cp(T)\u27s are calculated by using direct integration over energy levels of the internal rotational potentials. The values of ΔHf°298 are determined using isodesmic reactions with group balance. Groups for use in Benson type additivity estimations are determined for the carbon bonded to oxygen and chlorine(s). Hydrogen bond increment groups for the chloroalkoxy, hydroxy chloroalkyl radicals and interaction terms for peroxy group with chlorine(s) are developed for group additivity approach. The reactions of alkyl radical with oxygen are important rate controlling processes in the low and intermediate temperature chemistry of hydrocarbon oxidation, especially the chemistry which occurs prior to ignition in internal combustion engines and in cool flames. Thermochemical properties for reactants, intermediates, products and transition states in neopentyl radical + O2 reaction system are analyzed with ab initio and density functional calculations to evaluate reaction paths and oxidation kinetics. Rate constants to products and stabilized adducts of the chemically activated neopentyl-peroxy are calculated as function of pressure and temperature using Quantum Rice-RamspergerKassel analysis for k(E) and a master equation analysis for pressure fall-off An elementary reaction mechanism is constructed to model experimental OH and HO2 formation profiles. Aromatic compounds are an important component of higher-octane automotive fuels and consequently they are present in emissions from incomplete combustion and other evaporation from solvents and fuels handling and storage. Oxidation reactions of ortho-xylene are studied to identify the important reaction channels of this class of highoctane aromatics. Elementary reactions, energy well depths, and absolute rate constants of benzylic radical derived from ortho-xylene, 2-methylbenzyl radical with O2, are determined with computational chemistry at density functional levels

Separation and Volatility of Locational Marginal Prices in Restructured Wholesale Power Markets

This study uses an agent-based test bed ("AMES") to investigate separation and volatility of locational marginal prices (LMPs) in an ISO-managed restructured wholesale power market operating over an AC transmission grid. Particular attention is focused on the dynamic and cross-sectional response of LMPs to systematic changes in demand-bid price sensitivities and supply-offer price cap levels under varied learning specifications for the generation companies. Also explored is the extent to which the supply offers of the marginal (price-determining) generation companies induce correlations among neighboring LMPs. Related work can be accessed at: http://www.econ.iastate.edu/tesfatsi/AMESMarketHome.htmRestructured wholesale power markets; multi-agent learning; demand-bid price sensitivity; AMES Wholesale Power Market Test Bed; agent-based modeling; locational marginal prices (LMPs); LMP separation; LMP volatility; supply-offer price caps

Identifying high-risk areas of N leaching in the Salt Lake Valley

Nitrogen (N) fertilization of urban turf areas, and potential nitrate (NO3-N) leaching, may pose a hazard to groundwater quality. This research utilized a Geographic Information System (GIS) approach to estimate NO3-N leaching mass from urban turf areas based on a one-dimensional N leaching model and to classify the NO3-N leaching risk in the Salt Lake Valley, Utah, USA, based on soil texture. The methodology integrated a calibrated and verified Hydrus-1D N model, soil textures and urban turf areas to predict NO3-N leaching to groundwater. Thirty United States Geological Survey (USGS) residential wells were installed and sampled in 1999 for NO3-N concentration. A relationship between estimated NO3-N leaching from urban landscapes and groundwater NO3-N concentration was developed to determine the effect of soil texture and landscaped area on NO3-N leaching from urban landscapes. The GIS approach was used to estimate the NO3-N leaching risk to groundwater under efficient irrigation and fertilization scenarios and over-irrigation and over-fertilization scenarios. The results showed that soil texture played a role in NO3-N leaching from urban landscapes to groundwater, and shallow groundwater was more susceptible to surface contamination compared to deep groundwater. The GIS technique identified areas where improved irrigation and fertilization management could reduce landscape NO3-N leaching significantly, resulting in fewer NO3-N leaching risk areas in the Salt Lake Valley, Utah, USA