bluuebunny/crossref_metadata_2025_split huggingface dataset:
Drop behaviour in a kühni column for a low interfacial tension system
Authors: Haunold Christophe , Cabassud Michel , Gourdon Christophe , Casamatta Gilbert 
Published: March 2009

AbstractIn order to simulate the hydrodynamics in a liquid‐liquid extraction column, a drop population model has been developed (Casamatta, 1981), taking into account the fundamental mechanisms: drop breakage, transport, and coalescence. Results of a set of experiments devoted to the description of drop breakage and transport in a Kuhni column stage are presented. A comparison between simulation results and experimental mean hold‐up and Sauter mean diameter data collected in a Kuhni column is finally undertaken, which leads to a study of the sensitivity of the model according to the transport and breakage parameters.
An evaluation of multiple binary interaction parameters in cubic equations of state
Authors: Trebble M. A. 
Published: March 2009

AbstractThree cubic equations of state are utilized in regressing a large vapour‐liquid equilibrium data bank using single and multiple binary interaction parameters. A second binary interaction parameter is shown to be both physically significant and useful in improving the match of experimental data, particularly in polar systems. The use of a third binary interaction parameter in the Trebble‐Bishnoi equation of state is found to be of value in systems with large molecular size differences.
Recursive least squares based estimation schemes for self‐tuning control
Authors: Shah Sirish L. , Cluett William R. 
Published: March 2009

AbstractRecursive Least Squares (RLS) is the most popular parametric identification method used for on‐line process model estimation and self‐tuning control. The basic least squares scheme is outlined in this paper and its lack of ability to track changing process parameters is illustrated and explained. Several variants of the basic algorithm which have appeared elsewhere in the literature are discussed. Some of these algorithms contain different modifications to the basic scheme which are intended to prevent this loss of alertness to changing process parameters. Other variations of the least squares algorithm are presented which attempt to deal with parameter estimation in the presence of disturbances and unmodelled process dynamics.
A two‐fluid model for non‐equilibrium two‐phase critical discharge
Authors: Schwellnus C. F. , Shoukri M. 
Published: March 2009

AbstractA general two‐fluid model is developed to predict critical (choked) flow of initially saturated or subcooled flow from pipes and nozzles. The model contains improvements in the basic formulation, constitutive relations and solution technique over previously published models. It consists of six conservation equations as well as a seventh equation representing bubble growth in bubbly flow. It allows for hydrodynamic as well as thermal non‐equilibrium. The model considers the development of three flow regimes, namely, bubbly, churn and annular flow regimes. The model predictions were compared with the limited available experimental data for which the axial pressure distributions were recorded. Excellent agreement was obtained.
Polymer alloys and blends: Recent advances
Authors: Favis Basil D. 
Published: March 2009

AbstractPolymer alloys and blends represent one of the fastest growing sectors of the plastics industry. To a large degree, the emphasis has now shifted from developing blends in the reactor to their creation through melt mixing on processing equipment such as extruders. As a result, intense activity is now being directed at controlling two particularly important considerations during melt processing: interfacial interactions and dispersed phase morphology. In this review, recent developments and trends in these two areas will be examined.
State estimation for continuous emulsion polymerization
Authors: Gagnon Louise , Macgregor J. F. 
Published: March 2009

AbstractVarious aspects of the use of extended Kalman Filters for tracking the states of continuous emulsion polymerization reactors are investigated. The importance of introducing meaningful nonstationary stochastic states to account for unknown impurities, initiator efficiencies, modelling errors, etc. is illustrated. The robustness of these state estimators to unmodelled and unmeasured disturbances, to modelling errors, and to input errors is evaluated. A procedure for selecting an optimal set of on‐line sensors is presented. The emulsion polymerization of styrene‐butadiene rubber (SBR) is used as the example system.
Equilibrium conditions for methane hydrate formation in aqueous mixed electrolyte solutions
Authors: Dholabhai P. D. , Englezos P. , Kalogerakis N. , Bishnoi P. R. 
Published: March 2009

AbstractEquilibrium data on the formation of methane hydrate in six mixtures of NaCl and KCl, six mixtures of NaCl and CaCl2 and a mixture of eight electrolytes found in sea water were experimentally obtained. The ionic strength (in molality units) of the NaCl and KCl mixtures ranged from 0.97 to 4.72 and that of the NaCl and CaCl2 mixtures from 1.27 to 3.90. The experimental temperatures ranged from 264 to 284 K and the pressures from 2.5 to 9.7 MPa.Equilibrium pressures predicted using a recently proposed method (Englezos and Bishnoi, 1988) have been compared with the data obtained and it was found that the predictions match the data very well. The standard errors for the mixtures of NaCl and KCl, NaCl and CaCl2 and the synthetic sea water were 5.54, 3.5 and 1.4%, respectively. The largest prediction error for an experimental data point was 10.1%.
Behaviour of absorption/stripping columns for the CO2‐MEA system; Modelling and experiments
Authors: Escobillana Germán P. , Saez Jorge A. , Pérez‐Correa José R. , Neuburg Heinz J. , Kershenbaum Lester S. 
Published: March 2009

AbstractA model is presented for the steady‐state simulation of a CO2 recovery pilot plant with aqueous monoethanolamine (MEA) solutions. CO2 absorption is performed in a column packed with 2.54 cm ceramic Pall rings. CO2 recovery is achieved in a 20 sieve tray steam stripping column.The packed column absorption model was fitted to the experimental data using the specific interfacial area of the irrigated packing as an adjustable parameter. The equivalent average bubble diameter was used as the adjusting parameter in the sieve tray stripping column.Modelling of both towers reproduces within 3% average error concentrations measured in a pilot plant. Measured temperatures were also well correlated.
Homogeneous azeotropic distillation: Comparing entrainers
Authors: Laroche L. , Andersen H. W. , Morari M. , Bekiaris N. 
Published: March 2009

AbstractIn this article, we present practical solutions (in the case of entrainers which add no azeotropes) to two problems of industrial relevance: Given a binary azeotrope which we want to separate into pure components, and a set of candidate entrainers, how do we determine which one is the best? Also, for each of these entrainers, what is the flowsheet of the feasible separation sequence(s)? We obtain these solutions by analyzing in details the mechanisms by which heavy, intermediate and light entrainers make separation feasible, using the new notions of equivolatility curves, of isovolatility curves and of local volatility order. We show that the second question finds an easy solution from the volatility order diagram.This analysis shows that a good entrainer is a component which “breaks” the azeotrope easily (i.e., even when its concentration is small) and yields high relative volatilities between the two azeotropic constituents. Because these attributes can be easily identified in an entrainer from the equivolatility curve diagram of the ternary mixture azeotropic component #1 — azeotropic component #2 — entrainer, we can easily compare entrainers by examining the corresponding equivolatility curve diagrams. Finally, we demonstrate the validity and limits of this method with examples.
Local drop size variation in an agitated vessel
Authors: Chriistodoulou Dimitrios , Stamatoudis Michael 
Published: March 2009

AbstractThe local droplet diameters were measured at two positions inside the circulation region of a stirred tank. The Sauter mean diameter near the top of the vessel was always 1.4 times greater than the one just outside the impeller region for rotational speeds of 250, 300, 350 and 400 rpm and for hold‐up fractions of 0.01, 0.025 and 0.05. The drop size distributions at a hold‐up fraction 0.01 had one mode for all impeller speeds studied and at both positions. At higher hold‐up fractions the distributions usually were bimodal.
Extraction of phenols: I. distribution of individual phenols between organic solvents and water or aqueous solvents
Authors: Bízek V. , Horáček J. , Procházka J. 
Published: March 2009

AbstractThe distribution of phenol and o‐cresol between water or aqueous solutions of sodium hydroxide and n‐heptane, toluene or methyl‐isobutyl‐ketone (MIBK) was investigated. A mathematical model of extraction was formulated and its parameters were estimated for each solute‐solvent pair.
The effect of pre‐wetting on dynamic contact angles
Authors: Ghannam M. T. , Esmail M. N. 
Published: March 2009

AbstractA roll‐coating experimental system is used to study the effect of pre‐wetting on dynamic contact angles, the interfacial displacement depth, and the associated phenomenon of air entrainment. The system consists of a roll, which is horizontally rotating in a liquid pool. The dynamic contact angle is recorded by a macrophotography system. The test liquids are glycerol solutions with viscosities in the range 104 < μ < 748 mPa · s. The value of (μV/ρg)0.5 is taken as the characteristic length to be used in the dimensionless relationships which correlate experimental measurements. The effect of base layer entry angle into the liquid pool on the dynamic contact angles and other flow parameters is studied. Comparison is made with measurements in dry tape‐coating and other pre‐wet roll–coating systems.
Modelling of turbulent flow and mass transfer with wall function and low‐reynolds number closures
Authors: Neŝić S. , Adamopoulos G. , Postlethwaite J. , Bergstrom D. J. 
Published: March 2009

AbstractA recent laser doppler anemometer study, by other researchers, of turbulent flow through a sudden expansion has been simulated using a kinetic energy of turbulence‐dissipation rate of turbulence (k ‐ ϵ) model. The near wall region was modelled in two different ways; using wall functions (WF), and a low‐Reynolds number (LRN) formulation.The reattachment length under particular flow conditions was obtained. Radial profiles for the mean axial and radial velocity, turbulence kinetic energy and Reynolds shear stress were determined for six locations downstream of the sudden expansion. Both models performed reasonably well in predicting the flow with the LRN approach performing slightly better than the WF approach near to the wall.The application of the LRN approach to the calculation of local mass transfer rates in wall bounded complex turbulent flows is demonstrated.
Slow non‐newtonian flow through packed beds: Effect of zero shear viscosity
Authors: Jaiswal A. K. , Sundararajan T. , Chhabra R. P. 
Published: March 2009

AbstractThe slow non‐Newtonian (inelastic) flow through packed beds of mono‐size spherical particles has been simulated by solving the equations of motion numerically. The inter‐particle interactions have been modelled by using a simple cell model. Theoretical estimates of pressure, friction and total drag coefficients as function of the pertinent physical (l≥n≥ 0.2; 0.3 ≤ e ≤ 0.5) and kinematic parameters (0.01 ≤ '≤ 100) for a fixed value of Reynolds number {Re = 0.001) have been obtained. The theoretical predictions reported herein have been validated using the suitable experimental results available in the literature, and the importance of including the zero shear viscosity in analyses for the creeping flow problems is convincingly demonstrated.
Coking threshold in hydroprocessing of asphaltenic oils
Authors: Kriz J. F. 
Published: March 2009

AbstractThe coking propensity of asphaltenic oils is quantitatively described using experimentally determined threshold values for temperature and hydrogen pressure. Results using this method are compared with more conventional information based on solubility properties. The threshold values are shown to be more pertinent for quantitative analyses. A model exponential function based on a simple mechanistic consideration is fitted through experimental points and used to explain curve patterns.
Global optimization of the bifunctional catalyst problem
Authors: Luus Rein , Bojkov Bojan 
Published: March 2009

AbstractAs shown by Luus et al. (1992), determination of the optimum catalyst blend along a tubular reactor to maximize the yield of a particular component is a difficult problem due to the large number of local optima. By using iterative dynamic programming, the effects of the region reduction factor and the choice of the initial region size are analyzed in detail for this problem. Even if a single grid‐point for the state is used, the likelihood of obtaining the global optimum is very high if the initial region size is chosen to be sufficiently large.
Modeling of the 3D hydrodynamics of 2‐blade impellers in stirred tanks filled with a highly viscous fluid
Authors: Abld Mohammed , Xuereb Catherine , Bertrand Joël 
Published: March 2009

AbstractThis paper deals with mixing in stirred tank reactors by paddle agitators and two‐blade impellers with different blade widths. Computational Fluid Dynamics (CFD) is used to solve the 3D hydrodynamics and to obtain at every point the flow patterns, the stress components and the viscous dissipation function. From the latter information, the power consumption is calculated. These results are compared with available experimental data: good agreement is observed. For example, for a paddle agitator, the flow is essentially plane far away from the horizontal walls. That means that, in order to create an axial circulation in the volume of the tank, the impeller height has to be decreased.This work documents the ability of CFD to model changes in flow patterns for three dimensional flows in stirred tanks.
Thermal diffusion in inclined flat‐plate columns of the frazier scheme
Authors: Yeh Ho‐Ming 
Published: March 2009

AbstractThe separation theory of thermal diffusion in inclined flat‐plate columns of the Frazier scheme has been developed and investigated. The equations for the best angle of inclination and maximum separation have been derived. Considerable improvement in separation is obtained when thermal diffusion columns are operated at the best angle of inclination.
Viscosity: A critical review of practical predictive and correlative methods
Authors: Monnery Wayne D. , Svrcek William Y. , Mehrotra Anil K. 
Published: March 2009

AbstractThis paper reviews methods for the prediction and correlation of Newtonian viscosity for pure components and mixtures of dilute gases, dense gases and liquids, focussing on those which are suited for practical engineering use. The methods reviewed were chosen because they are well known and accepted or appear potentially promising. They are categorized as theoretical, semi‐theoretical or empirical and further distinguished as predictive or correlative.Brief derivations with relevant equations and discussions on limitations and reliability of results are presented. In addition, the applicability and average deviations for each method are tabulated, with the recommended methods clearly stated. Furthermore, some gaps in viscosity prediction/correlation are identified and promising approaches are discussed.
Heat‐Transfer analysis for quenched impact test specimens of polymers
Authors: Bui V. T. , Liu T. M. 
Published: March 2009

AbstractAn approximate but simple method for the low temperature mechanical testing of polymers is frequently used. It consists of quenching the polymer sample into liquid nitrogen and then installing it on the testing apparatus. The required test temperature is determined by the time where the experiment is started. In this work, the time‐temperature patterns of two quenched impact test samples, in high density polyethylene and polyurethane, were first measured and then compared with the values obtained from a graphical method of unsteady‐state heat conduction. The agreement between experimental data and calculated values is better than 8% in terms of relative error.
Solubility / retention relationships in supercritical‐fluid chromatography
Authors: Gonenc Z. Sermin , Akman Ugur , Sunol Aydin K. 
Published: March 2009

AbstractThe effects of temperature, pressure and supercritical fluid density on solubility‐retention relationship of solutes in supercritical fluid partition chromatography are investigated. New retention data for naphthalene and phenanthrene are obtained as a function of pressure at different temperatures. The mobile‐phase partial molar volumes of the solutes are determined from infinite‐dilution fugacity coefficients and used to model the pressure dependence of solute retention that reveals the nature of interactions between the stationary phase and the solute. Relationships between pressure and temperature dependence of solubility and retention of solutes are also illustrated.
An algorithm for the simulation of electrohydrodynamic rigid particulate flows
Authors: Hsu H. Y. , Sharma N. , Patankar Neelesh A. 
Published: March 2009

AbstractIn this communication, a numerical technique for electrohydrodynamic rigid particulate flows is presented. The proposed algorithm takes advantage of a specialized rigid particle formulation, thus enabling an efficient computational approach. The approach is tested for all the basic dielectrophoretic behaviors expected in DC and AC fields. This tool has potential use in several micro‐ and nano‐scale fabrication processes that rely on electrohydrodynamic self‐assembly of particles. Copyright © 2009 John Wiley & Sons, Ltd.
A delay decomposition approach to delay‐dependent stability for linear systems with time‐varying delays
Authors: Zhang Xian‐Ming , Han Qing‐Long 
Published: March 2009

AbstractThis paper is concerned with delay‐dependent stability for linear systems with time‐varying delays. By decomposing the delay interval into multiple equidistant subintervals, on which different Lyapunov functionals are chosen, and new Lyapunov‐Krasvskii functionals are then constructed. Employing these new Lyapunov‐Krasvskii functionals, some new delay‐dependent stability criteria are established. The numerical examples show that the obtained results are less conservative than some existing ones in the literature. Copyright © 2009 John Wiley & Sons, Ltd.
State estimation of stochastic systems with switching measurements: A polynomial approach
Authors: Germani A. , Manes C. , Palumbo P. 
Published: March 2009

AbstractThe state estimation problem is here investigated for a class of stochastic linear switching‐output systems, in which the output matrix switches in a finite set of possible values according to a not directly measured discrete Markov sequence. This note presents a real‐time algorithm, based on the optimal polynomial filtering approach, which achieves the simultaneous estimation of both the continuous system state and the switching parameter. The state and observation noises do not need to be Gaussian. It is shown that the optimal filter of degree one (best affine filter) does not solve the parameter estimation problem, due to a structural first‐order unobservability property, and therefore the use of higher‐order filters becomes necessary. As an application of the proposed filter, the problem of the online simultaneous estimation of the transmitted signal and of the impulse response samples of a multipath fast‐fading digital communication channel is considered in this paper. Differently from other approaches, the polynomial filter solves the problem without the use of training sequences (preambles) in the transmitted data, so that the information flow through the channel is not interrupted. Copyright © 2009 John Wiley & Sons, Ltd.
Adenotonsillectomy for obstructive sleep apnea in obese children: A meta‐analysis
Authors: Costa Dary J. , Mitchell Ron 
Published: March 2009

ObjectiveThe purpose of this study was to determine the effectiveness of adenotonsillectomy (T&A) for treating obstructive sleep apnea (OSA) in obese children.Data SourcesPubMed and Ovid databases.Review MethodsA meta‐analysis of studies that reported sleep parameters in obese children with OSA before and after T&A. Data were analyzed using the random effects model. Statistical significance was P ≤ 0.05.ResultsData from four studies that included 110 children were analyzed. The mean sample size was 27.5 (range, 18–33). The mean body mass index z score was 2.81. The mean pre‐ and postoperative apnea‐hypopnea index (AHI) was 29.4 (range, 22.2–34.3) and 10.3 (range, 6.0–12.2), respectively. The weighted mean difference between pre‐ and postoperative AHI was a significant reduction of 18.3 events per hour (95% confidence interval [CI], 11.2–25.5). The mean pre‐ and postoperative oxygen saturation nadir was 78.4 percent (range, 73.9%‐81.1%) and 85.7 percent (range, 83.6%‐89.9%), respectively. The weighted mean difference was a significant increase of the oxygen saturation nadir of 6.3 percent (95% CI, 3.9–8.7). Forty‐nine percent of children had a postoperative AHI <5, 25 percent of children had a postoperative AHI <2, and 12 percent of children had a postoperative AHI <1.ConclusionsT&A improves but does not resolve OSA in the majority of obese children. The efficacy and role of additional therapeutic options require more study. The high incidence of obesity in children makes this a public health priority.
Do Mediterranean cricketsGryllus bimaculatusDe Geer (Orthoptera: Gryllidae) come from the Mediterranean? Largescale phylogeography and regional gene flow
Authors: Ferreira M. , Ferguson J.W.H. 
Published: March 2009

AbstractWe investigate the degree of between-population genetic differentiation in the Mediterranean field cricketGryllus bimaculatus, as well as the possible causes of such differentiation. Using cytochromebmtDNA sequences, we estimate genetic variation inG. bimaculatusfrom seven South African and two Mediterranean populations. Within-population genetic variation in Europe (two haplotypes, one unique to a single individual) suggest low effective population size and strong bottlenecks with associated founder effects, probably due to cold winter environments in Europe that limit reproduction to a short part of the summer. The likely cause for this is the daily maxima in winter temperatures that fall below the critical level of 16°C (enabling normal calling and courtship behaviour) in Mediterranean Europe, whereas the equivalent temperatures in southern Africa are above this limit and enable reproduction over a large part of the year. European genetic variants were either shared with Africa or closely related to African haplotypes. For survival, European populations are probably dependent on immigration from other areas, including Africa. South African populations have low but measurable gene flow with Europe and show significant between-population genetic differentiation (30 haplotypes). Isolation-by-distance is not sufficient to explain the degree of between-population genetic differences observed, and a large degree of dispersal is also required in order to account for the observed patterns. Differences in morphology and calling behaviour among these populations are underlied by these genetic differences.