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Unified Model (unified + model)
Selected AbstractsUsing an intensity-scale technique to assess the added benefit of high-resolution model precipitation forecastsATMOSPHERIC SCIENCE LETTERS, Issue 2 2006Marion P. Mittermaier Abstract Deterministic precipitation forecasts from the 12- and 4-km versions of the Unified Model (UM) were compared using an intensity-scale technique. Averaging raw model output is always recommended to minimise grid-scale errors. The retained detail in averaged 4-km forecasts produces an improved prediction of larger accumulations. © Crown Copyright 2006. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] Mortgage Terminations, Heterogeneity and the Exercise of Mortgage OptionsECONOMETRICA, Issue 2 2000Yongheng Deng As applied to the behavior of homeowners with mortgages, option theory predicts that mortgage prepayment or default will be exercised if the call or put option is ,in the money' by some specific amount. Our analysis: tests the extent to which the option approach can explain default and prepayment behavior; evaluates the practical importance of modeling both options simultaneously; and models the unobserved heterogeneity of borrowers in the home mortgage market. The paper presents a unified model of the competing risks of mortgage termination by prepayment and default, considering the two hazards as dependent competing risks that are estimated jointly. It also accounts for the unobserved heterogeneity among borrowers, and estimates the unobserved heterogeneity simultaneously with the parameters and baseline hazards associated with prepayment and default functions. Our results show that the option model, in its most straightforward version, does a good job of explaining default and prepayment, but it is not enough by itself. The simultaneity of the options is very important empirically in explaining behavior. The results also show that there exists significant heterogeneity among mortgage borrowers. Ignoring this heterogeneity results in serious errors in estimating the prepayment behavior of homeowners. [source] A Unified Dynamic Model Formulation for Robotic Manipulator SystemsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2003Anjan Kumar Swain This paper addresses the problem of the formulation of a unified dynamic model for sundry robotic manipulator systems derived from the first principle of mechanics instead of the existing formulation based on linear separability principle. It provides a systematic derivation, evaluation, and subsequent conceptual interpretation of manipulator dynamics model. Further, it analyzes the generality of the unified model over a wide range of manipulator configurations. In addition, it describes the implementation aspects of the unified model. © 2003 Wiley Periodicals, Inc. [source] A unified model of property integration for batch and continuous processesAICHE JOURNAL, Issue 7 2010Cheng-Liang Chen Abstract This article aims to present a general model for synthesis of property-based resource conservation networks. The proposed model is applicable to batch and continuous processes. Therein, the process systems are characterized by properties instead of composition that is found in most published works to date in the area of resource conservation. By treating continuous process as a special case of batch processes, both kinds of operations can be optimized with a unified model that is developed on the basis of a superstructure. The overall framework of property network is adopted, where material reuse/recycle, interception, and waste treatment are all taken into consideration. Apart from direct reuse/recycle, interception devices are employed to improve stream properties for further recovery, whereas effluent treatment is needed for compliance with environmental discharge limits. In addition, storage vessels are employed in batch processes to override intrinsic time constraint. Four case studies are solved to illustrate the proposed approach. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Unified model for nonideal multicomponent molecular diffusion coefficientsAICHE JOURNAL, Issue 11 2007Alana Leahy-Dios Abstract Multicomponent diffusion is important in a variety of applications. In order to calculate diffusion flux, molecular diffusion coefficients are required, where fluid nonideality and the multicomponent nature of the mixture have a significant effect. A unified model for the calculation of diffusion coefficients of gas, liquid and supercritical states of nonpolar multicomponent mixtures is presented. A new correlation is proposed for the binary infinite dilution-diffusion coefficients. The generalized Vignes relation is used in multicomponent mixtures. Nonideality is rigorously described by the fugacity derivatives evaluated by the volume-translated Peng-Robinson equation of state. Predictions for highly nonideal gas and liquid multicomponent mixtures demonstrate the reliability of the proposed methodology. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] A REGIONAL ECONOMY, LAND USE, AND TRANSPORTATION MODEL (RELU-TRAN©): FORMULATION, ALGORITHM DESIGN, AND TESTING,JOURNAL OF REGIONAL SCIENCE, Issue 3 2007Alex Anas ABSTRACT RELU is a dynamic general equilibrium model of a metropolitan economy and its land use, derived by unifying in a theoretically valid way, models developed by one of the authors [Anas (1982), Anas,Arnott (1991, 1997), Anas,Kim (1996), Anas,Xu (1999)]. RELU equilibrates floor space, land and labor markets, and the market for the products of industries, treating development (construction and demolition), spatial interindustry linkages, commuting, and discretionary travel. Mode choices and equilibrium congestion on the highway network are treated by unifying RELU with the TRAN algorithm of stochastic user equilibrium [Anas,Kim (1990)]. The RELU-TRAN algorithm's performance for a stationary state is demonstrated for a prototype consisting of 4-building, 4-industry, 4-labor-type, 15-land-use-zone, 68-link-highway-network version of the Chicago MSA. The algorithm solves 656 equations in a special block-recursive convergent procedure by iterations nested within loops and loops within cycles. Runs show excellent and smooth convergence from different starting points, so that the number of loops within successive cycles continually decreases. The tests also imply a numerically ascertained unique stationary equilibrium solution of the unified model for the calibrated parameters. [source] Glass Transition of Low-Dimensional PolystyreneMACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2004Qing Jiang Abstract Summary: A unified model is developed for the finite size-effect on the glass-transition temperature of polymers, Tg(D), where D denotes the diameter of particles or thickness of films. In terms of this model, Tg depends on both the size and interface conditions. The predicted results are consistent with the experimental evidence for polystyrene (PS) particles and films with different interface situations. Tg(D) function of free-standing PS films. [source] A unified model for the evolution of galaxies and quasarsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2000Guinevere Kauffmann We incorporate a simple scheme for the growth of supermassive black holes into semi-analytic models that follow the formation and evolution of galaxies in a cold dark matter-dominated Universe. We assume that supermassive black holes are formed and fuelled during major mergers. If two galaxies of comparable mass merge, their central black holes coalesce and a few per cent of the gas in the merger remnant is accreted by the new black hole over a time-scale of a few times 107 yr. With these simple assumptions, our model not only fits many aspects of the observed evolution of galaxies, but also reproduces quantitatively the observed relation between bulge luminosity and black hole mass in nearby galaxies, the strong evolution of the quasar population with redshift, and the relation between the luminosities of nearby quasars and those of their host galaxies. The strong decline in the number density of quasars from z,2 to z=0 is a result of the combination of three effects: (i) a decrease in the merging rate; (ii) a decrease in the amount of cold gas available to fuel black holes, and (iii) an increase in the time-scale for gas accretion. The predicted decline in the total content of cold gas in galaxies is consistent with that inferred from observations of damped Ly, systems. Our results strongly suggest that the evolution of supermassive black holes, quasars and starburst galaxies is inextricably linked to the hierarchical build-up of galaxies. [source] Dynamic organization of COPII coat proteins at endoplasmic reticulum export sites in plant cellsTHE PLANT JOURNAL, Issue 6 2009Sally L. Hanton Summary Protein export from the endoplasmic reticulum (ER) is mediated by the accumulation of COPII proteins such as Sar1, Sec23/24 and Sec13/31 at specialized ER export sites (ERES). Although the distribution of COPII components in mammalian and yeast systems is established, a unified model of ERES dynamics has yet to be presented in plants. To investigate this, we have followed the dynamics of fluorescent fusions to inner and outer components of the coat, AtSec24 and AtSec13, in three different plant model systems: tobacco and Arabidopsis leaf epidermis, as well as tobacco BY-2 suspension cells. In leaves, AtSec24 accumulated at Golgi-associated ERES, whereas AtSec13 showed higher levels of cytosolic staining compared with AtSec24. However, in BY-2 cells, both AtSec13 and AtSec24 labelled Golgi-associated ERES, along with AtSec24. To correlate the distribution of the COPII coat with the dynamics of organelle movement, quantitative live-cell imaging analyses demonstrated that AtSec24 and AtSec13 maintained a constant association with Golgi-associated ERES, irrespective of their velocity. However, recruitment of AtSec24 and AtSec13 to ERES, as well as the number of ERES marked by these proteins, was influenced by export of membrane cargo proteins from the ER to the Golgi. Additionally, the increased availability of AtSec24 affected the distribution of AtSec13, inducing recruitment of this outer COPII coat component to ERES. These results provide a model that, in plants, protein export from the ER occurs via sequential recruitment of inner and outer COPII components to form transport intermediates at mobile, Golgi-associated ERES. [source] Communicating quality: a unified model of disclosure and signallingTHE RAND JOURNAL OF ECONOMICS, Issue 4 2008Andrew F. Daughety Firms communicate product quality to consumers through a variety of channels. Economic models of such communication take two alternative forms when quality is exogenous: (i),disclosure of quality through a credible direct claim; or (ii),signalling of quality via producer actions that influence buyers' beliefs about quality. In general, these two literatures have ignored one another. We argue that firms should be viewed as choosing which means of communication they will employ. We show that integration of these two alternatives leads to new implications about disclosure, signalling, firm preferences over type, and the social efficiency of the channel of communication employed. [source] A unified model of sigmoid tumour growth based on cell proliferation and quiescenceCELL PROLIFERATION, Issue 6 2007F. Kozusko Objectives: A class of sigmoid functions designated generalized von Bertalanffy, Gompertzian and generalized Logistic has been used to fit tumour growth data. Various models have been proposed to explain the biological significance and foundations of these functions. However, no model has been found to fully explain all three or the relationships between them. Materials and Methods: We propose a simple cancer cell population dynamics model that provides a biological interpretation for these sigmoids' ability to represent tumour growth. Results and Conclusions: We show that the three sigmoids can be derived from the model and are in fact a single solution subject to the continuous variation of parameters describing the decay of the proliferation fraction and/or cell quiescence. We use the model to generate proliferation fraction profiles for each sigmoid and comment on the significance of the differences relative to cell cycle-specific and non-cell cycle-specific therapies. [source] The vascular biology of hypertension and atherosclerosis and intervention with calcium antagonists and angiotensin-converting enzyme inhibitorsCLINICAL CARDIOLOGY, Issue S5 2001Carl J. Pepine M.D. Recent advances in the understanding of vascular disease genesis suggest that atherosclerosis and hypertension, primary targets of therapy in the INternational VErapamil SR/trandolapril STudy (INVEST), are closely related. A unified model for the development of cardiovascular disease (CVD) is emerging from recent advances related to atherosclerosis and hypertension. The process of vascular disease appears to begin early in life, when signs of endothelial dysfunction first appear. A primary cause of CVD progression is increased oxidative stress in the endothelium caused by multiple risk factor conditions, including heredity, dyslipidemia, smoking, diabetes, and elevated systolic blood pressure (SBP > 110 mmHg). The renin-angiotensin and kallikrein-kinin systems are important regulators of blood pressure and atherosclerosis. In the reninangiotensin system, angiotensin-converting enzyme (ACE) mediates generation of angiotensin II (ang II) at local vascular sites and in the plasma and also degrades bradykinin. Information derived from INVEST will help to identify treatment strategies, such as those containing a calcium antagonist and an ACE inhibitor, that are targeted directly at the vascular disorder responsible for hypertension and atherosclerosis. [source] Reviving Inert Knowledge: Analogical Abstraction Supports Relational Retrieval of Past EventsCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 8 2009Dedre Gentner Abstract We present five experiments and simulation studies to establish late analogical abstraction as a new psychological phenomenon: Schema abstraction from analogical examples can revive otherwise inert knowledge. We find that comparing two analogous examples of negotiations at recall time promotes retrieving analogical matches stored in memory,a notoriously elusive effect. Another innovation in this research is that we show parallel effects for real-life autobiographical memory (Experiments 1,3) and for a controlled memory set (Experiments 4 and 5). Simulation studies show that a unified model based on schema abstraction can capture backward (retrieval) effects as well as forward (transfer) effects. [source] |