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The electrodialysis reversal (EDR) technology was applied as tertiary treatment for final effluent from a Kraft pulp mill industry located in Bahia, Brazil. Two samples were evaluated: first, the final effluent treated by conventional processes (FE); the second one was additionally filtered by sand and activated carbon (FEAC). The tests in a pilot plant were carried out in batch mode, with electrode's polarity reversion. Temperature, pH and electrical conductivity measurements were performed during EDR treatment. Solutions before and after the EDR treatment were submitted to physicochemical characterization in order to determine the system efficiency. Chloride and sulfide concentrations have been reduced by up to 98.6 and 100% respectively. Only for FE treatment it was observed fouling and scaling occurrence, due to high organic and inorganic ions concentrations. In addition, the evaluated ions were satisfactorily removed by EDR for both effluents, giving to them the suitable quality for disposal or reuse in industrial processes. The study presents a mitigating solution to environmental and technological problems, itself as a viable alternative in the tertiary treatment of effluents from the Kraft process in the pulp industry. [ABSTRACT FROM AUTHOR]

The objective of this work is to recycle used engine oil until it is converted into an alternative fuel by catalytic pyrolysis. The effect of using eggshell ash as a catalyst in pyrolysis reactions on the yield of the resulting fractions was investigated. In addition, the influence of this catalyst on the compositions and the quality of the non-condensable gas and liquid fractions were analyzed. The results show that the liquid fraction recovered 97.02%wt; with 20%wt of the catalyst is predominant. The detection of aromatics 15.84%wt, olefins 32.74%wt, naphthenic 2.82%wt, paraffins 29.00%wt, and alcohols 20.50%wt, in the pyrolytic liquid and the observation of H2 15.22%wt, CH4 16.65%wt and other elements such as C4H8 21.93%wt in non-condensable gases, make it possible to predict the good usability of these products obtained as an alternative fuel. [ABSTRACT FROM AUTHOR]

This paper presents an improved correlation for thermophysical properties of binary mixtures. The new correlation permits calculation of excess properties and property deviations, and it has the capability of correlating and predicting different functional forms of the thermophysical properties within the experimental uncertainties. This paper contains examples for: molar volume, kinematic and dynamic viscosity, surface tension, refractive index, heat capacity and thermal conductivity. [ABSTRACT FROM AUTHOR]

In 1871, Josef Stefan established the theoretical framework which allowed the design of his diffusion column. It consisted of a volatile liquid A overlaid with gases A and B. A steady gas B sweep flowed at the top, maintaining the concentration of gas A close to zero at that location. Binary gas diffusion coefficients, whose magnitudes are crucial in many mass transfer operations, were estimated with this device. This line of work was continued uninterruptedly by many research groups around the world for over eight decades. However, in the 1950s inaccuracies in the diffusivity estimates were detected mainly due to column end effects such as gas turbulence/eddy formation resulting from the sweeping stream as well as interfacial curvature. The latter affects the transport area and the path length of gas A to the top. Studies departing from the traditional Stefan column role of binary diffusivity estimation were promptly initiated to attain a better understanding of transport phenomena within the column. These efforts, which endure to this day, applied fundamental chemical engineering principles to determine the source of the diffusivity inaccuracies, the dimensionality of gas transport, the importance of interfacial curvature and nonisothermal column operation, and how liquid-phase events such as mixing affect device performance. These research initiatives have led to an in-depth description of transport phenomena within the Stefan column. Historical references are thoroughly analyzed, chemical engineering contributions to this field are highlighted, and perspectives for future theoretical and experimental work along these lines are presented. [ABSTRACT FROM AUTHOR]

The Stefan column was designed in the 19th Century to estimate binary gas diffusivities by placing a pure volatile liquid at the bottom overlaid with a stagnant gas. A steady gas sweep at the top removed the diffused species. Previous validation, by other research groups, of the Maxwell-Stefan multicomponent mass transport equations in the Stefan column prompted a study to test an azeotropic binary liquid as the source of both gaseous species, maintaining the composition at the liquid-gas interface constant. Azeotropic acetone (A)-n-hexane (B) mixtures were placed in a vertical glass pipette in preparation for an isothermal evaporation-diffusion experiment in atmospheric air (C). The pure solvents were also tested separately. The experimental interfacial descent, the solvents' diffusivities in air, and their molar fluxes were provided as input to the Maxwell-Stefan equations to obtain the binary gas diffusivity DAB,exp, which is unavailable in the literature. The pure solvent diffusivities in air showed good agreement with the Chapman-Enskog kinetic theory for low-density gases, but the experimental gas diffusivity of acetone in n-hexane exceeded consistently the theoretical predictions by at least two orders of magnitude. A possible explanation for this unexpected result is the high affinity between the solvent molecules in the liquid state, which undoubtedly affects their gas transport behavior. Further studies are necessary to elucidate this finding. This is the first attempt to use a liquid azeotrope in a Stefan column. By combining this approach with the Maxwell-Stefan transport equations, the gas diffusivity of acetone in n-hexane was obtained. [ABSTRACT FROM AUTHOR]

The Stefan column was developed in the 19th Century to estimate binary gas diffusivities, DAB's, and this goal has been achieved by many research groups. In the classical device, volatile liquid A is placed at the bottom and overlaid with stagnant gas B. A slow gas B sweep is provided at the top to remove the diffused gas A. However, column "end effects" have been largely ignored or neglected during data analysis. The present study addressed the effect of interfacial curvature on diffusivity determination. Curvature affects the interfacial transport area and the diffusion path length of gas A. Cylindrical aluminum punches with flat or curved tips were used to imprint solid naphthalene surfaces. The naphthalene-containing tubes were subjected to standard Stefan column sublimation-diffusion experiments at ∼60 °C and atmospheric pressure. With the mass loss from each tube obtained gravimetrically and the punch/tube dimensions, the experimental diffusivities, DAB,exp, were determined using the solution to a one-dimensional mass transport model for gas A. Tubes with flat interfaces had the smallest DAB,exp errors relative to the literature, while the curved surfaces (spherical and elliptical) had the largest when assumed to be flat in the calculations. When curvature was accounted for mathematically, the DAB,exp errors changed sign and magnitude depending on the actual punch shape and system dimensions. This is the first study to show that neglect of interfacial curvature can lead to significant errors in DAB,exp obtained using the isothermal Stefan column method. Therefore, curvature corrections should be considered whenever accurate DAB,exp's are sought. [ABSTRACT FROM AUTHOR]

The Stefan diffusion column was designed in the 19th Century to determine binary gas diffusivities, DAB's. Typically, pure liquid A is overlaid by gases A and stagnant B, with a steady gas B sweep at the top to remove the evaporated-diffused A. Experimental diffusivities DAB,exp may be obtained from transient interfacial descent data, but column end effects impacting such determination have been ignored or neglected in the literature. This study addresses experimentally and theoretically for the first time the role played by liquid phase composition on DAB determination using the Stefan column. Specifically, changes in interfacial curvature were sought by adding a nonvolatile liquid I (glycerol) to a volatile liquid A (ethanol). Mixtures of known initial composition xA0 were tested in isothermal evaporation-diffusion experiments at ∼65 °C using atmospheric air (B). A one-dimensional transport model for gas A was used to analyze the interfacial descent data. The average DAB,exp errors did not differ significantly between the liquid mixture groups and those for pure ethanol (range for the latter of +9.9 to +17.1%). However, considerable scatter in DAB,exp occurred as the mixtures became more dilute in ethanol, with the coefficient of variation increasing more than ten-fold in the xA0 = 0.146 group. This variability cannot be explained by differences in surface tension exclusively, but may also result from changes in liquid physical and transport properties as well as diffusion of liquid A. A more comprehensive modeling of the liquid phase in conjunction with gas phase transport is necessary to obtain accurate DAB's. [ABSTRACT FROM AUTHOR]

Two adsorbents, pristine electric arc furnace slag (EAFS) and alkali activated slag (AAS) were used for Cu2+ removal from aquatic solutions. Batch adsorption tests were conducted at various temperatures and initial Cu2+ concentrations, while solid to liquid ratio and pH of solution were kept constant. Pseudo-first-order and pseudo-second-order (PSO) kinetics models, Langmuir and Freundlich isotherm models, as well as intraparticle and Boyd's diffusion models were applied in order to investigate the adsorption process. It has been found that alkali activation of EAFS leads to an increase in the specific surface of slag and thus improves the sorption properties of EAFS. The adsorption of Cu2+ onto both adsorbents proceeds via PSO adsorption mechanism, film diffusion mainly controls the adsorption process, and Langmuir isotherm model fits well the experimental data. Results indicated a fast adsorption process which is spontaneous and endothermic in nature. Microstructural investigation of EAFS and AAS revealed morphological changes in metal loaded EAFS and AAS samples in comparison to unloaded adsorbents. X-ray powder diffraction analysis indicated that adsorption of Cu2+ onto both adsorbents occurs through formation of a Cu-complex. [ABSTRACT FROM AUTHOR]

This study was developed based on the possibility of reusing and valuing the alginate extraction residue (RES) from the algae Sargassum filipendula. The adsorptive properties of RES were explored through kinetic and equilibrium assays in batch mode, in which the kinetic equilibrium time (200 min) was not influenced by the increase of the initial concentration of Ni solutions and the sorption process was favored by the temperature increase. The modeling revealed the simultaneous occurrence of physical and chemical interactions with the external diffusion as the predominant step. The Langmuir model was more representative for the equilibrium results, with an uptake capacity comparable to that of other biomaterials. The thermodynamic study indicated a spontaneous, favorable, and endothermic process, besides the presence of the ion exchange. The isoelectric point was found at pH 5.3, and the pore size distribution allowed the classification of RES as macroporous. The simplified bath sorption design revealed that the required mass of RES become greater for higher quality degrees. However, it is tenable to consider this process viable due to the easy access to the algae biomass and the large amount of the solid waste generated from the alginate extraction (∼50%), termed as residue (RES). [ABSTRACT FROM AUTHOR]

The Stefan column consists of liquid A evaporating into an inert/stagnant gas B with a sweeping B stream at the top. It was designed to estimate binary gas diffusivities, DAB's, but "end effects" such as gas mixing at the top and interfacial curvature have been either ignored or uncorrelated to the operational settings. This study's hypothesis is that gas mixing at the top and the gas–phase aspect ratio affect DAB estimation in the acetone (A)-ambient air (B) system at 50 °C. The sweeping stream Reynolds number (Re) and the gas–phase aspect ratio (AR = initial gas phase height to column internal diameter) were the variables tested. Isothermal evaporation-diffusion experiments were conducted in which the temporal interfacial descent was tracked. The settings were 492 ≤ Re ≤ 5378 and AR between 5 and 15. A 1D transport model allowed determination of the experimental diffusivity, DAB,exp, by nonlinear regression. For Re < 600, the DAB,exp errors relative to DAB,CE (predicted by the Chapman–Enskog kinetic theory for low-density gases) were small and unrelated to AR, while for Re > 600 the errors increased considerably with Re and were inversely proportional to AR. This study is the first to relate the column's operational settings to the DAB estimation errors. The column should be operated at low sweeping gas Re and large AR for accurate DAB,exp's. The low Re region deserves further study, while the present transport model may have to be replaced by computational fluid dynamics simulations to account for the multidimensional gas flow patterns. [ABSTRACT FROM AUTHOR]

Although several studies show that Schinus terebinthifolius Raddi fruits are a promising source of bioactive compounds, few studies have investigated the anticancer activity of its essential oil (EO). The objective of this study was therefore to investigate the antiproliferative activity of S. terebinthifolius fruit EO against eight human tumor cell lines. A central composite rotatable design with 11 experiments was developed to investigate the optimal conditions of hydrodistillation by Clevenger apparatus. EO obtained at optimized conditions (yield greater than 6.7%) showed potent activity for all cell lines investigated; the most promising results were observed against leukemia, kidney, multidrug-resistant ovarian, and prostate tumor cell lines. Gas chromatography-mass spectrometry revealed the following major compounds in the EO: δ-3-carene (33.78-36.73%), α-phellandrene (15.67-17.30%), limonene (15.03-16.32%), α-pinene (7.03-9.20%), and germacrene D (4.98-6.99%). Future work involving fractionation of the EO might shed some light on the compounds responsible for each antiproliferative activity. [ABSTRACT FROM AUTHOR]

Binary gas diffusivities DAB’s are extremely useful in the analysis/design of mass transfer systems and to develop correlations. This study used an unsteady experimental method to determine DAB’s in gas pairs starting with a sublimating solid (A) such as naphthalene or camphor and air (B). The cumulative fractional mass transferred from the surface of a solid A sphere placed concentrically within an isothermal spherical enclosure was followed gravimetrically with time. The experimental DAB,exp for the gas pair was determined by nonlinear regression using the solution to a transient, one-dimensional (radial) diffusion model. The model’s Case 1 option assumed impermeability (no flux of gas A) at the enclosure’s outer surface, while Case 2 assumed zero concentration of gas A at the same location. For naphthalene-air, DAB,exp overestimated the literature values, the errors ranging from −110 to −185% for Case 1 and −21 to −65% for Case 2. For camphor-air, the error in DAB,exp was −36% for Case 1 and −16% for Case 2. DAB,exp for camphor in atmospheric air is herein reported for the first time. Potential improvements to the experiments include automation of the sphere melt-casting process and tighter control of the enclosure’s environmental conditions. Likewise, the theoretical model could be extended to three dimensions with multicomponent diffusion to assess the effect of air humidity on the transport of gas A. This is the first attempt to determine DAB,exp for naphthalene-air and camphor-air from an unsteady sublimation-diffusion experiment and to model the results using rigorous mass transport theory. [ABSTRACT FROM AUTHOR]

The main objective is studying the fundamental aspect, by means of drying kinetics and the application of forced convective drying of wastewater sludge with the determination of the optimum drying conditions. The drying system is composed of two units; small samples of 2.5 g are dried in the first unit and a bed of sludge weighing 250 g is dried in the second unit. The experiments are performed under air temperatures varying between 80°C and 200°C. The range of the air velocity and its humidity is 1–2 m/s and 0.005–0.05 kgwater/kgdry air, respectively. The experiments are performed for two different sludges: activated sludge (AS) and thermalized and digested sludge (TDS). Usually, three main drying phases are observed during drying of bed of sludge. These phases are reduced to only two for small samples. Determination of the influent parameters shows that the temperature of the drying air and sludge origin can profoundly influence the drying kinetic of the sludge. The exergy analysis of the two units of the drying system allows selecting 140°C, 2 m/s, and 0.05 kgwater/kgdry airas optimum drying conditions with an exergy efficiency reaching 90%. [ABSTRACT FROM PUBLISHER]

In this article, a design method for a PID controller is proposed based on IMC principles for control of open loop integrating and unstable first-order processes with time delay. The design is based on H2optimal closed-loop transfer function for set point changes and step input disturbances. The method has one tuning parameter, and systematic guidelines are provided for the selection of this tuning parameter based on peak value of the sensitivity function. The performance of the designed controller is verified on various integrating and unstable processes, and it is observed that nominal and robust control performance is achieved with the proposed design method. Improved closed-loop performance was obtained when compared to other methods recently reported in the literature. Further, the proposed method provides good closed-loop performance even when there are large uncertainties in the process parameters. [ABSTRACT FROM AUTHOR]

The study investigates the effectiveness and energy conservation potential of a high rate hybrid up-flow anaerobic sludge blanket (UASB) reactor treating a combination of domestic waste activated sludge and distillery's spent wash. Analysis of the results revealed good organic removal efficiency at a hydraulic retention time of 5 days. However, the economic feasibility was not studied. This corresponded to an average percentage COD removal of 65%, an average percentage BOD removal of 40.41%, and an average total suspended solids removal of 87%. Biogas volumes were measured using a water displacement technique, and a steady biogas production rate of 2 L/day was attained after 71 days of substrate and nutrient addition. Two well-known mathematical models were used to estimate biogas volume. Hill's model was found to be in better agreement with experimental results; it is within ±10%. Based on the results obtained, the construction of a hybrid anaerobic sludge blanket reactor at a water treatment facility for the biodegradation of distillery spent wash and domestic waste to produce biogas and energy is unquestionably a lucrative and sustainable venture. [ABSTRACT FROM AUTHOR]

Densities and viscosities of the binary mixtures of acetic acid with ethylene glycol and diethylene glycol were measured over the entire range of composition at five temperaturesT = 303.15, 308.15, 313.15, 318.15, and 323.15 K. The excess molar volumes and viscosity deviations were calculated and fitted to the Redlich-Kister type polynomial equation. The viscosity data reported herein were used to examine the modeling capabilities of viscosity equations based on Eyring's absolute reaction rate theory and excess Gibbs free energy functions, namely, the Eyring-Van Laar, the Eyring-Scatchard and Hamer, and the Eyring-UNIQUAC equations. Some one-parameter models such as the Fang and He equation and the Grunberg and Nissan equation were also tested. [ABSTRACT FROM PUBLISHER]

The optimal design of a divided wall distillation column (DWC) involves a number of variables and is a multivariable nonlinear problem. Various process parameters such as reflux rate, liquid split, and vapor split affect the product quality and energy efficiency of a DWC. Response surface methodology (RSM) based on Box-Behnken surface statistical design (BBD) was used in this article to study the process parameter optimization. A commercial process simulation software was used for rigorous simulation using several multicomponent mixtures. It was found that the number of simulation runs reduced significantly for the optimization of a DWC using BBD. The optimization results of RSM take care of interactions between process variables, and the predictions agreed well with the rigorous simulation results. [Supplementary materials are available for this article. Go to the publisher's online edition ofChemical Engineering Communicationsfor the following free supplemental resources: 17 data tables.] [ABSTRACT FROM AUTHOR]

This article reports the esterification of lauric acid and methanol studied using a thermally coupled distillation sequence with a side rectifier and the Petlyuk distillation column. The product of the esterification can be used as biodiesel. It was found that the thermally coupled distillation sequence with a side rectifier can produce ester with a high purity (around 0.999) and also pure water, and the excess of methanol is recovered in the side rectifier. The results indicate that the energy requirement of the complex distillation sequence with a side rectifier can be reduced significantly by varying operational conditions. These reductions in energy requirements can be interpreted as reductions in carbon dioxide emissions. Moreover, dynamic tests for control of the composition of the ester and control of two temperatures for the thermally coupled distillation sequence with a side rectifier indicate that it is possible to eliminate disturbances in the feed composition, while the composition of the biodiesel remains at the desired value. [ABSTRACT FROM AUTHOR]

Aluminum corrosion rate was studied in the absence and presence of some tertiary ketonic Mannich bases in 2 M HCl solution, using weight loss and galvanostatic polarization techniques. The two methods gave similar results. The results showed that the inhibitor efficiency increases with increasing inhibitor concentration and decreases with increasing the temperature of the system. The adsorption of these Mannich bases on Al surface is found to obey Temkin's adsorption isotherm. Galvanostatic polarization studies showed that these compounds are mixed-type inhibitors. Some thermodynamic parameters were computed and discussed. Finally, the influence of the chemical structure of the tertiary ketonic Mannich bases on their inhibition efficiencies is discussed. [ABSTRACT FROM AUTHOR]

This work presents a novel integrated reactive-separation design based on a dividing-wall column (DWC) applied to an industrial case study within AkzoNobel Chemicals. To the best of our knowledge this is one of the first reported industrial applications of a reactive DWC. Due to changing market conditions, one of the by-products in a plant became more economically attractive than the main product. However, the design of the existing plant does not allow an increase of the by-product production rate at the cost of the main product. To solve this problem we developed a novel integrated design that combines reaction and separation into a feasible reactive DWC that allows 35% savings in capital and 15% savings in energy costs. This article describes the novel reactive DWC design, presents the rigorous simulation results, and makes a comparison with the base case alternative. [ABSTRACT FROM AUTHOR]

The effects of thermal links on the closed-loop dynamics of thermally coupled distillation sequences for the separation of quaternary mixtures have been studied in this work by using rigorous dynamic simulations. The incorporation of thermal links into conventional distillation sequences can lower the energy consumption up to 40% without introducing additional control problems to the resulting thermally coupled distillation sequences. In some cases, the thermally coupled distillation sequences outperformed the dynamic behavior of the conventional distillation sequences for set point tracking. This result is important to establish that thermally coupled distillation sequences not only can have significant energy savings but also good dynamic properties. [ABSTRACT FROM AUTHOR]

Josef Stefan developed the theoretical framework needed to analyze the diffusion column in the second half of the 19th century. For the next six decades after his death, his design allowed the estimation of binary gas diffusivities assuming a flat liquid–gas interface and isothermal operation at atmospheric pressure. In the 1950s, inaccuracies in the diffusivity estimates were detected. These were related to column end effects at the top, where turbulence and eddy formation at the mixing point of the sweep and gas phases occurred, and at the liquid–gas interface, where curvature due to surface tension changed the mass transfer area and the diffusion path length for gas A to the top. The present work examines quantitatively for the first time the relationship between interfacial curvature resulting from surface tension and the binary gas diffusivity estimates in the Stefan column. The hypothesis is that such a relationship exists. The dimensionless parameter N1, which gives the ratio of surface tension to gravitational forces acting on the interface, determines the radial distribution profile, in turn affecting the curved-to-flat-interface binary gas diffusivity ratio. The generalized surface tension model was validated numerically with interfacial descent versus time data from two Stefan column runs reported recently (acetone-air and n-hexane-air). The experimental curved-to-flat-interface diffusivity ratio in both runs was 1.7–1.8, indicating an important contribution from interfacial curvature in the diffusivity calculations. The researcher now has a quantitative tool relating interfacial curvature due to surface tension and the binary gas diffusivity estimates obtained in the Stefan column. [ABSTRACT FROM AUTHOR]

The Stefan column was designed in the 19th century to allow the experimental estimation of binary gas diffusion coefficients starting with a pure volatile liquid A placed at the bottom overlaid with a stagnant/inert gas B. A sweeping B stream was provided at the top to remove the diffused gas A. In 1959, Richardson first studied a two-component liquid mixture in the Stefan column. One of his systems, a high-density volatile liquid A (carbon tetrachloride) dissolved in a low-density nonvolatile liquid O (dibutyl phthalate), is of interest to our ongoing research efforts. He collected interfacial descent-time data in his single isothermal Stefan column experiment, and analyzed them with a diffusion transport model, which contained unnecessary assumptions and simplifications, to obtain the binary liquid diffusivity of A in O, DAO. The present study removes the major restrictions of the previous model, reanalyzing the reported data with an improved numerical diffusion model that includes realistic features of the one-dimensional transport problem and statistical information on the estimated DAO. The average ± standard deviation of DAO were 8.82E-10 ± 1.85E-15 m2/s (12 data points), with an error of −13.3% relative to the Richardson value. The new model also provides detailed insight on the diffusive transport dynamics of liquid A by predicting interfacial descent rates, instantaneous concentration profiles in the liquid phase, and the time-dependent fraction of the mass of A lost from the original solution. The model is valuable to chemical engineering researchers studying diffusion–evaporation phenomena and multicomponent distillation processes. [ABSTRACT FROM AUTHOR]

In-situ Fourier transform infrared spectroscopy measurements were obtained by using an innovative equipment to study the heterogeneous reaction between a hydrolyzed porous methylsilsesquioxane film and hexamethyldisilazane (HMDS) dissolved in CO2at supercritical conditions. Gas and solid infrared signatures were separated to obtain kinetic information of the heterogeneous reaction. A two-step reaction mechanism was observed: a fast first step controlled by kinetics and a second step controlled by the diffusion of the HMDS inside the porous material. Infrared information was used to derive a rate law expression of the silylation reaction between HMDS and Si-OH. A first order of reaction relative to the concentration of hydrophilic sites was observed with activation energy of 51.85 ± 1.25 kJ/mol. [ABSTRACT FROM PUBLISHER]

Surface functionalization of hydrolyzed methyl-silsesquioxane films were performed by treatment of samples with trimethylchlorosilane (TMCS) and methyltrichlorosilane (MTCS) dissolved in supercritical carbon dioxide. Films thicknesses modifications, pore size distributions, hydrophobicity, dielectric constants, and chemical reaction analyses were performed by ellipsometry, ellipsometric porosimetry, goniometry, electrical measurements, and Fourier transform infrared spectroscopy, respectively. As results, the properties of the functionalized films were able to be modified in function of reaction conditions (concentration, temperature, and/or pressure). Layers thicker than a monolayer were deposited by both TMCS and MTCS, and a tradeoff between the surface functionalization and layer thickness for both chemicals was observed. The results led to the conclusion that a combination of reagents or processing steps could be used for surface properties tuning. [ABSTRACT FROM PUBLISHER]

This article demonstrates the existence of multiple optimal control profiles for the fermentation process involvingSaccharomyces cerevisiae. The Jones–Kompala model is used to model the dynamics of the fermentation process. Both dilution rate and the oxygen mass transfer coefficient are used as the control variables individually and together. While it was demonstrated recently that the steady-state optimization for the Jones–Kompala model would reveal multiple optimum solutions, this work demonstrates the existence of multiple optimum control profiles when dynamic optimization is performed. To perform the dynamic optimization, the differential equations were converted to a nonlinear program (NLP) using Radau collocation with finite elements and the state-of-the-art optimization program CONOPT (constrained optimizer) was used to obtain the local optimum profiles. The global solution was confirmed using the deterministic global optimization program branch-and-reduce optimization navigator. Both the programs were accessed through the network enabled optimization system (NEOS) server. [ABSTRACT FROM PUBLISHER]

A general coordinate-system invariant solution for the magnetic field and flux density within and surrounding a spherical particle in a linearly magnetizable medium in an arbitrary, externally applied field is developed for cases where the particle possesess homogeneous permanent and/or linear magnetization. The solution is consistent with the equations of magnetostatics and asymptotically exact in a regular perturbation sense, where the expansion parameter is the ratio of particle radius a to characteristic length scale L for variations in the externally applied field. Expressions for the magnetic field and flux, accurate to O(a/L), are used to determine the magnetic force and couple exerted on the particle by integration of the Maxwell stress tensor over the particle surface. This result is shown to be the same for some of the various reported expressions for the magnetic body force density (e.g., the Kelvin, Helmholtz, and Korteweg-Helmholtz) and is consistent with previously derived expressions for the magnetic force. It is further shown that the effective dipole method yields results consistent with these calculations. The results may be applied to the analogous electrostatic situation by replacing the magnetic quantities by their electric analogues. [ABSTRACT FROM AUTHOR]

The article offers information on the research works of Howard Brenner, the Willard H. Dow Professor of Chemical Engineering at Massachusetts Institute of Technology (MIT) from 1981 to 2008. He was on the faculties at New York University from 1955-1965, Carnegie Mellon University from 1966-1977, and the University of Rochester from 1977-1981. He has written more than 200 articles, 35 book chapters, and three books.