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Modified Models (modified + models)

Distribution by Scientific Domains

Medical Sciences	40%

Selected Abstracts

Influences of occlusal and skeletal discrepancies on biomechanical environment in the TMJ during maximum clenching: an analytic approach with the finite element method

JOURNAL OF ORAL REHABILITATION, Issue 9 2001
E. Tanaka
The purpose of this study was to investigate the influences of occlusal and skeletal discrepancies on temporomandibular joint (TMJ) stresses during maximum clenching. A three-dimensional (3-D) finite element model of the mandible including the TMJ was developed as a standard model. Furthermore, nine modified models were established; one dentoalveolar open bite model and eight skeletal open bite models with varying gonial angles or mandibular plane angles (FMAs). For the dentoalveolar open bite model, the TMJ stresses were larger than those for the standard model, although the distribution pattern was not essentially varied. In the skeletal open bite model with greater gonial angle or FMA, the TMJ stresses were significantly larger than those in the dentoalveolar open bite model. In conclusion, the TMJ stress was affected by occlusal and/or skeletal discrepancies, if coexisted in particular, indicating the association with degenerative changes of the TMJ components. [source]

Phase equilibrium in supercritical CO2 mixtures using a modified Kwak-Mansoori mixing rule

AICHE JOURNAL, Issue 2 2004
José O. Valderrama
Abstract The mixing rules proposed by Kwak and Mansoori for the Peng-Robinson equation of state have been modified to describe vapor-liquid equilibrium in mixtures that contain supercritical CO2. Data in the literature for nine binary liquid,vapor systems containing supercritical CO2 are used for testing the modified models. The systems studied were binary mixtures containing carbon dioxide with lauric acid, palmitic acid, oleic acid, linoleic acid, 1-octanol, 1-decanol, 2-methyl-1-pentanol, ,-pinene, and limonene. The modifications studied included the introduction of a nonquadratic mixing rule proposed by one of the authors and a different interaction parameter for the volume constant of the equation of state. Compared to results in the literature, the Kwak-Mansoori combining rules and the proposed empirical modifications give lower deviations in correlating the solute concentration in the vapor phase, the most important variable for the design of supercritical extraction processes. Contrary to arguments found in the literature, it is also demonstrated that a severe test for an equation of state and its mixing rules is the correlation of the solute concentration in vapor,liquid mixtures. © 2004 American Institute of Chemical Engineers AIChE J, 50: 480,488, 2004 [source]

Extracting Economic Cycles using Modified Autoregressions

THE MANCHESTER SCHOOL, Issue 5 2001
Alex S. Morton
We review a family of modified autoregressive models in both discrete- and continuous-time formulations. We present the case for these models by showing first how a standard discrete-time autoregressive model with orders selected by criteria such as the Akaike information criterion can fail to identify the correct periods of cyclical variations in a simulated example. We then show how the modified models can overcome this failure, and further illustrate this success with a real example of an unemployment series. A new extension of the continuous-time modified model to multivariate series is described. This is applied to a pair of series with mixed monthly, quarterly and annual sampling intervals. Common cyclical components of the two series are then extracted. [source]

Kinetic modeling of cellulosic biomass to ethanol via simultaneous saccharification and fermentation: Part I. Accommodation of intermittent feeding and analysis of staged reactors

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009
Xiongjun Shao
Abstract The model of South et al. [South et al. (1995) Enzyme Microb Technol 17(9): 797,803] for simultaneous saccharification of fermentation of cellulosic biomass is extended and modified to accommodate intermittent feeding of substrate and enzyme, cascade reactor configurations, and to be more computationally efficient. A dynamic enzyme adsorption model is found to be much more computationally efficient than the equilibrium model used previously, thus increasing the feasibility of incorporating the kinetic model in a computational fluid dynamic framework in the future. For continuous or discretely fed reactors, it is necessary to use particle conversion in conversion-dependent hydrolysis rate laws rather than reactor conversion. Whereas reactor conversion decreases due to both reaction and exit of particles from the reactor, particle conversion decreases due to reaction only. Using the modified models, it is predicted that cellulose conversion increases with decreasing feeding frequency (feedings per residence time, f). A computationally efficient strategy for modeling cascade reactors involving a modified rate constant is shown to give equivalent results relative to an exhaustive approach considering the distribution of particles in each successive fermenter. Biotechnol. Bioeng. 2009;102: 59,65. © 2008 Wiley Periodicals, Inc. [source]

Mouse isolated perfused heart: Characteristics and cautions

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2003
Fiona J Sutherland
Summary 1.,Owing to the considerable potential for manipulating the murine genome and, as a consequence, the increasing availability of genetically modified models of cardiovascular diseases, the mouse is fast becoming a cornerstone of animal research. However, progress in the use of various murine preparations is hampered by the lack of facilities and skills for the adequate physiological assessment of genetically modified mice. 2.,We have attempted to address this problem by refining and characterizing a mouse isolated heart preparation that was originally developed for use with larger hearts. 3.,We used the isolated buffer-perfused Langendorff preparation (perfused at constant flow or constant pressure) to characterize: (i) the frequency,response characteristics; (ii) heart isolation conditions; (iii) perfusion chamber conditions; (iv) temperature,function relationships; (v) stability over extended periods of perfusion; (vi) perfusate calcium,function relationships; (vii) pressure,volume relationships; (viii) pressure,rate relationships; and (ix) flow,function relationships. [source]