bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance assessment of processes with abrupt changes of disturbances
Authors: Huang Biao 
Published: March 2009

AbstractThis paper is concerned with feedback controller performance assessment of time‐variant processes due to abrupt changes of disturbances. It is shown that in addition to minimum variance control, alternative performance benchmarks that are more suitable for time‐variant processes can be found from routine operating data. Three types of performance assessment problems and their solutions are discussed. The proposed methods are illustrated through a simulated example as well as a case study on Shell distillation column data.
The fouling of alloy‐800 heat exchange surfaces by magnetite particles
Authors: Basset Mark , Mcinerney Jeff , Arbeau Norm , Lister Derek H. 
Published: March 2009

AbstractThe deposition of magnetite particles from suspension in water at nominally 90°C onto Alloy‐800 surfaces has been studied by chemical and radiotracing techniques under various conditions of flow, chemistry and boiling heat transfer. The experiments indicated that, under non‐boiling conditions, mechanisms based on diffusion and thermophoresis control deposition while removal is negligible. For sub‐cooled boiling at a low rate, the trapping of particles by bubbles is important; at a high rate, deposition during micro‐layer evaporation dominates. Removal occurs during sub‐cooled boiling and is nicely described by a mathematical model in which it proceeds concomitantly with deposition.
Voidage and particle velocity profiles in a spout‐fluid bed
Authors: Pianarosa Denis L. , Freitas Luis A. P. , Lim C. Jim , Grace John R. , Dogan O. Murat 
Published: March 2009

AbstractDetailed hydodynamic measurements have been obtained for fully cylindrical spout‐fluid beds of 1.3 mm, 1.8 mm and 2.5 mm glass beads in a fully cylindrical column of diameter 152 mm using three different types of optical fibre probes. The reallocation of up to 43% of the air to auxiliary air introduced through the conical base caused some decrease in spout voidages, but remarkably little change in spout diameter compared with spouted beds where there was no auxiliary air addition. Auxiliary air led also to some decrease in particle velocities in the spout and to a modest decrease in the net solids circulation rate.
Measurement and correlation of the individual ionic activity coefficients of aqueous electrolyte solutions of KF, NaF and KBr
Authors: Taghikhani Vahid , Vera Juan H. , Modarress Hamid 
Published: March 2009

AbstractIon selective electrodes were used to measure the activity coefficients of individual ions at 298.2 K in aqueous solutions of KF, KBr and NaF up to 3, 2 and 1 molal, respectively. The mean ionic activity coefficients of the electrolytes obtained from the values of individual ions show good agreement with values reported in the literature. The experimental results confirm that the activity coefficients are different for the anion and the cation in an aqueous solution of a single electrolyte. It is also confirmed that the deviation from ideality for each ion depends on its counterion. The Khoshkbarchi—Vera equation was used to correlate the experimental data.
Physical solubility of hydrogen sulfide in several aqueous solvents
Authors: Rinker Edward B. , Sandall Orville C. 
Published: March 2009

AbstractThe solubility of hydrogen sulfide in several aqueous solutions was measured over the temperature range 25°C to 60°C. The solvents investigated in this work include 0 to 50% aqueous solutions of polyethylene glycol, ethylene glycol, methyldiethanolamine and diethanolamine. The amine solutions used in this work were neutralized by the addition of hydrochloric acid in order to suppress the hydrogen sulfide reaction (H2S → H+ + HS−) so that only the physical solubility of hydrogen sulfide would be measured. The solubility data determined in this work are expressed in terms of Henry's law. The Henry's law constants found in this work were correlated well by a particularly simple empirical formula based on the molecular weight of the solvent.
Nonlinear control of competitive mixed‐culture bioreactors via specific cell adhesion
Authors: Kurtz Michael J. , Henson Michael A. , Hjortsø Martin A. 
Published: March 2009

AbstractA nonlinear control strategy is developed for competitive mixed‐culture bioreactors in which two cell populations compete for a common growth limiting substrate. A stream is periodically removed from the reactor, and the two cell populations are separated using specific cell adhesion. The steady state corresponding to the desired population fraction is stabilized by discarding faster growing cells and recycling slower growing cells to the reactor. The recycle loop must be operated periodically to allow regeneration of the adhesion column after each separation. As a result, the manipulated input is chosen as the sampling interval during which material is removed from the reactor. The nonlinear controller is designed using a simplified dynamic model that assumes continuous separation of the cell populations. The controller is implemented by calculating the sampling interval that leads to the same amount of material being removed from the reactor as that computed from the continuous control law. A nonlinear, closed‐loop observer is used to generate one‐time‐delay‐ahead predictions of the measured cell concentrations and the unmeasured substrate concentration. The efficacy of the proposed control strategy is evaluated via simulation.
Étude de l'influence de l'évaporation d'un bac d'eau sur les transferts dans un canal corrugué
Authors: Maamir Seghir , Zeghmati Belkacem , Hadjadj Ahmed , Rondot Daniel 
Published: March 2009

AbstractLes auteurs présentent une étude numérique et expérimentale des transferts qui s'effectuent par convection forcée dans un canal comportant une protubérance sinusoîdale et par convection naturelle dans un bac d'eau. L'étude numérique a été effectuée pour des nombres de Reynolds compris entre 35 et 350, plusieurs densité de flux de chaleur et pour des amplitudes de la protubérance comprises entre 0.005 et 0.02 m. Les résultats montrent que la diffusion de la vapeur d'eau dans l'air modifie le profil des lignes de courant qui devient convexe au‐dessus de la surface libre de l'eau. En outre, l'evaporation atténue la perturbation engendrée par la protubérance et augmente les transferts de chaleur dans le canal. La visualisation de l'ecoulement, réalisée à l'aide d'un générateur de fumée d'encens, d'un laser à argon et d'une caméra vidéo à mis en évidence la complexité de l'interaction entre le flux de vapeur engendré par l'évaporation de l'eau du bac, l'écoulement de l'air dans le canal et les déperditions de chaleur à travers les parois latérales. Les résultats théoriques et expéri‐mentaux sont en bon accord qualitatif.
A generalized correlation of solute inclusion in ice formed from aqueous solutions and food liquids on sub‐cooled surface
Authors: Chen Ping , Chen Xiao Dong 
Published: March 2009

AbstractSolute inclusion in an ice layer formed on a smooth stainless steel surface under sub‐cooled flow conditions has been studied experimentally. The effects of ice growth rate, solution velocity and bulk concentration of solute on the solute inclusion in the ice layer have been investigated using a controlled flow surface crystallizer (CFSC). For several aqueous solutions (sucrose, NaCI, glycol, fructose), food liquids (skim milk, whole milk, orange juice) and particulate suspension (potato starch particles), the effective molecular weights were calculated and their effects on solid inclusion determined. This effect was then conveniently related to the freezing point depression (FPD) of each liquid tested. A generalized empirical correlation has been established for all the liquids tested.
Neural network‐based optimal iterative controller for nonlinear processes
Authors: Gao Furong , Wang Fuli , Li Mingzhong 
Published: March 2009

AbstractA new optimal iterative neural network‐based control (OINNC) strategy with simple computation and fast convergence is proposed for the control of processes with nonlinear dynamics. The process dynamics is captured by a forward neural network, and the control is determined by a simple iterative optimization during each sampling interval based on a linearized neural network model. In addition, a feedback control is incorporated into the system to compensate for any model mismatches and to reject disturbances. With the proposed system, the tracking error is shown to be confined to the origin. An application of the proposed OINNC scheme to a nonlinear process results in superior performance when compared with a well‐tuned conventional PID controller.
RTD studies in a falling film graphite evaporator with internal spiral fins: Influence of the geometry
Authors: Bessenet Sébastien , Renaudin Viviane , Leclerc Jean‐Pierre , Hornut Jean‐Marie 
Published: March 2009

AbstractA hydrodynamic study of a new graphite evaporator has been performed. In this exchanger the fluid flows as a thin film on a spirally wound fin which forms a spiral staircase inside a tube. The slope θm of the spirally wound fin is modifiable. The residence time distribution (RTD) of the film was measured for different fin slopes θm and several film flowrates mf. The flow pattern was then modelled thanks to the DTS software as a cascade of perfect mixed cells and the mean residence time τm was calculated. The evolution of τm as a function of θm and mf is accurately represented by a power law relation.
One‐ and two‐phase isochoric heat capacity measurements of aqueous solution of nacl near the critical point of pure water
Authors: Abdulagatov Ilmutdin M. , Dvoryanchikov Vasilii I. , Kamalov Abdurakhman N. , Abramova Elena G. , Abdurashidova Madina A. 
Published: March 2009

AbstractIsochoric heat capacities of H2O+NaCl solutions (0.0031 and 0.0063 mole fraction of NaCl) were measured with a high temperature and high pressure adiabatic calorimeter near the sub‐critical and near the supercritical point of pure water. Temperatures ranged from 361 to 677 K. Measurements were made at six densities, namely: 367.07 and 485.59 kg·m−3 for x = 0.0031 mol fraction of NaCl and 388.65, 560.03, 607.05, and 973.70 kg·m−3 for x = 0.0063 mol fraction of NaCl. Measurements were conducted in the two‐and one‐phase regions including near phase transition temperatures TS(ρ). The phase transition temperatures TS(ρ) and saturated isochoric heat capacity values CVX have been determined for each isochore. The uncertainty in heat capacity measurements is estimated to be 3.5% to 4.5% near the phase transition and critical points. Present and previous results of heat capacity measurements were compared with predictions from the crossover (CREOS) and Pitzer—Tanger–Hovey equations of state (PTH EOS). Our previous heat capacity measurements were found to deviate systematically from crossover‐model predictions. The present results show good agreement with the crossover model for the composition x = 0.0031 mol fraction.
Improving the simplified‐perturbed‐hard‐chain theory equation of state using a new non‐attracting hard‐sphere equation
Authors: Nasrifar Kh. , Ayatollahi Sh. , Moshfeghian M. 
Published: March 2009

AbstractIn this research a new simple non‐attracting hard‐sphere equation is introduced. The equation meets the ideal gas and close‐packed limits and is in accordance with computer simulation data with reasonable accuracy. When this equation is used with the simpli‐fied‐perturbed‐hard‐chain theory equation of state, improvements on the calculation of vapour pressure and saturated liquid density of pure compounds are observed. For 35 pure compounds of different classes, the averages of absolute error are 3.31% and 4.20% for the calculation of vapour pressure and saturated liquid density, respectively. The respected errors for the original equation of state are 3.53% and 4.96%, respectively. Moreover, the use of the new hard‐sphere equation in place of the Carnahan‐Starling equation in the simplified‐perturbed‐hard‐chain theory equation of state, does not have any appreciable effect on the prediction of K factors in VLE calculations.
Esterification of ethanol with sulfuric acid: A kinetic study
Authors: Theodore Shammi , Sai P. S. T. 
Published: March 2009

AbstractExperiments were conducted in a stirred batch reactor under isothermal conditions for obtaining kinetics of the esterification reaction between ethanol and sulfuric acid. Reactive adsorption technique was employed to enhance the conversion. Anhydrous sodium sulfate was used as an adsorbing agent to remove the water formed during the reaction. The variables include the mole ratio of ethanol to sulfuric acid, reaction temperature, purity of the reactants, and the amount of adsorbing agent. The reaction was found to be reversible and second order at low mole ratios, and irreversible and first order at high mole ratios. The kinetic parameters of the rate law were estimated. A possible reaction mechanism was proposed and validated with the experimental data. The effect of the mole ratio of reactants, anhydrous sodium sulfate loading, and purity of the reactants on the yield of ethyl hydrogen sulfate was studied, using full‐factorial search and optimized conditions were obtained by the method of steepest ascent. More precise optimum conditions were obtained using the Box‐Wilson composite method.
An accurate model for prediction of gas hydrate formation conditions in mixtures of aqueous electrolyte solutions and alcohol
Authors: Javanmardi Jafar , Moshfeghian Mahmood , Maddox Robert N. 
Published: March 2009

AbstractA new thermodynamic model for calculating the hydrate formation temperature of different hydrate formers in aqueous solutions of both electrolytes and a single alcohol has been presented. This method uses a generalization of the Aasberg‐Petersen model for water activity. For calculation of water activity in the presence of electrolytes, the effect of alcohols was taken into account without using any new fitting parameters. The results are in good agreement with published experimental data. Calculated values of the hydrate formation temperature in the presence of alcohols and electrolytes are compared with those obtained by other existing models. The average absolute error of hydrate formation temperature for 524 available experimental data points is about 0.87 K.
On the costs of parameter uncertainties. Part 2: Impact of EVOP procedures on the optimization and design of experiments
Authors: Pinto José Carlos 
Published: March 2009

AbstractPinto (1998) showed that an economical value might be assigned to model parameter uncertainties, which could be used for process optimization and for taking decisions during sequential experimental designs. The procedure is extended to take into account the fact that plant operation conditions change with time, leading to improvements of the plant operation and allowing the partial recovering of losses introduced by uncertain parameters during plant design. It is shown that the use of EVOP (Evolutionary Operation Procedures) during plant operation may reduce the cost of parameter uncertainties, exerting a major impact on process optimization and optimal design of experiments.
On the use of heat belts for energy integration across many plants in the total site
Authors: Bagajewicz Miguel , Rodera Hernàn 
Published: March 2009

AbstractIndirect heat integration across plants using intermediate fluids is, in many cases, a preferable alternative to direct integration. Previous work has discussed the use of independent circuits capable of transferring the maximum possible heat. Piping cost and the location of the plants were proven an important factor when intermediate fluids are used. This paper analyzes the concept of a ‘heat belt’ that consists of a single‐pipe circuit used to extract heat from and release it to the plants. Since a general model is MINLP, the analysis focuses on the particular case of three plants for which an MILP model can be formulated.
Morphological changes of human skin cells exposed to a DC electric field in vitro using a new exposure system
Authors: Méthot Stéphane , Moulin Véronique , Rancourt Denis , Bourdages Michel , Goulet Daniel , Plante Michel , Auger Francois A. , Germain Lucie 
Published: March 2009

AbstractThe human skin contains a physiological battery that could be implicated in the healing process, by creating an endogenous electric field. Skin cells undergo morphological changes in response to an external DC electric field (EF). We found that fibroblasts reorient their cell bodies in a manner perpendicular to the EF direction, for normal and above physiological intensities. Actin and tubulin filaments (cytoskeleton proteins) follow the same pattern of reorientation. Keratinocytes tend to elongate in the same direction, although to a lesser extent. The study of the response of human skin cells to an external EF is a first step toward a better understanding of the mechanisms involved in wound healing and eventually toward the improvement of wound repair.
Solid‐liquid mass transfer in a rotary drum
Authors: Parsons Trevor G. , Masliyah Jacob H. , Gray Murray R. 
Published: March 2009

AbstractThe solid‐liquid mass transfer coefficient for slurries agitated in rotating drums with baffles was measured using the dissolution of β‐naphthol as a tracer in silica sand slurries. The effects of drum rotation rate (0.33 to 15 min−1), slurry holdup (4.4% to 17%) and solids volume fraction (0 to 0.62) on the solid‐liquid mass transfer were investigated with a slurry particle diameter of 4.6 × 10−4 m. Mass transfer coefficients were corrected for the effect of particle shrinkage due to dissolution of the tracer. The mass transfer coefficient increased with increasing rotational speed of the drum from 0.005 to 0.045 mm.5‐1. Two types of slurry motion were observed; well mixed slurry flowing over the baffles and segregation of solids on the baffles. The mass transfer coefficients from the present study, along with literature data, correlated with the Froude number to the 0.36 power, for Froude numbers from 10−6 to 10−1.
Kinetic analysis of phenol adsorption from aqueous systems
Authors: Mijangos Federico , Navarro Ana , Jodra Yolanda 
Published: March 2009

AbstractThe kinetic adsorption of mixtures of phenolic compounds onto a polymeric adsorbent from aqueous solutions was studied. Experimental data for single‐component solutions were obtained and fitted to a parallel diffusion model. Effective diffusion coefficients were related to liquid‐phase diffusion and surface diffusion. The effect of solute concentration and salinity on these parameters was also analysed. Van Laar's equation is proposed to evaluate the influence of concentration on diffusion. The adsorption kinetics for phenol and pcresol mixtures at different initial concentration ratios were determined and correctly adjusted to the mentioned kinetic model. Results confirm that adsorption from multicomponent aqueous solutions is a surface diffusion‐controlled process.
Quantitative multiplexed analysis of ErbB family coexpression for primary breast cancer prognosis in a large retrospective cohort
Authors: Giltnane Jennifer M. , Moeder Christopher B. , Camp Robert L. , Rimm David L. 
Published: March 2009

AbstractBACKGROUND:Assessment of outcome using a single prognostic or predictive marker is the current basis of targeted therapy, but is inherently limited by its simplicity. Multiplexing has provided better classification, but has only been done quantitatively using RNA or DNA. Automated quantitative analysis is a new technology that allows quantitative in situ assessment of protein expression. The authors hypothesized that multiplexed quantitative measurement of ErbB receptor family proteins may allow better prediction of outcome.METHODS:The authors quantitatively assessed the expression of 6 proteins in 4 subcellular compartments in 676 patients using breast carcinoma tissue microarrays. Then using Cox proportional hazards modeling and unsupervised hierarchical clustering, they assessed the prognostic value of the expression singly and multiplexed.RESULTS:Epidermal growth factor receptor (EGFR), HER‐2, and HER‐3 expression were associated with decreased survival. Multivariate analysis showed high HER‐2 and HER‐3 expression maintained independence as prognostic markers. Hierarchical clustering of expression data defined a small class enriched for HER‐2 expression with 40% 10‐year survival, compared with 55% using conventional methods. Clustering also revealed a similarly poor‐prognostic subgroup coexpressing EGFR and HER‐3 (but low for estrogen receptor, progesterone receptor, and HER‐2) with a 42% 10‐year survival.CONCLUSIONS:This work shows that the combined analysis of protein expression improved prognostic classification, and that multiplexed models were superior to any single‐marker–based method for prediction of 10‐year survival. These methods illustrate a protein‐based, multiplexed approach that could more accurately identify patients for targeted therapies. Cancer 2009. © 2009 American Cancer Society.
Serum high‐molecular weight adiponectin is related to early postprandial glycemic increases and gastric emptying in patients with type 2 diabetes mellitus
Authors: Iwase M. , Iino K. , Oku M. , Nohara S. , Asano T. , Doi Y. , Iida M. 
Published: March 2009

AbstractBackgroundPostprandial hyperglycemia and hyperlipidemia are frequently associated with type 2 diabetes mellitus. The aim of the present study is to investigate the clinical determinants of postprandial glycemia and lipemia, especially serum high‐molecular weight adiponectin.MethodsTwenty‐seven diabetic patients treated with diet alone and 13 healthy volunteers took liquid test meal containing 53 g carbohydrate and 47 g lipid, dosed with nonradioactive isotope 13C‐acetate. Venous blood and breath samples were obtained for 180 min after the meal. Gastric emptying was evaluated by peak excretion time of 13CO2 in the breath samples. Delayed gastric emptying was defined as peak excretion time > 2.5 h (mean + 2 SD in the healthy volunteers).ResultsDiabetic patients showed delayed insulin secretion, postprandial hyperglycemia and hyperlipidemia compared with control. Postprandial glycemic increases significantly correlated with enhanced gastric emptying. Serum high‐molecular weight adiponectin correlated with postprandial glycemic increases at 30 and 60 min after meal (r = 0.42, p < 0.05; r = 0.37, p < 0.05, respectively). Serum high‐molecular weight adiponectin also correlated with gastric emptying (versus peak excretion time r = − 0.58, p < 0.05). In addition, diabetic patients with delayed gastric emptying showed the suppressed postprandial glycemia with lower serum high‐molecular weight adiponectin than those with normal gastric emptying. On the other hand, postprandial increases in serum triglyceride were not related to serum high‐molecular weight adiponectin or gastric emptying, but significantly related to liver function test (serum transaminases) and body mass index.ConclusionsEarly postprandial glycemic increases were related to elevated serum high‐molecular weight adiponectin, which might be associated with enhanced gastric emptying. Copyright © 2009 John Wiley & Sons, Ltd.