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Dimensional Model (dimensional + model)
Selected AbstractsAnchoring Economic Predictions in Common KnowledgeECONOMETRICA, Issue 2 2002R. Guesnerie The paper examines within a unified methodology expectational coordination in a series of economic models. The methodology views the predictions associated with the Rational Expectations Hypothesis as reasonable whenever they can be derived from the more basic Common Knowledge Hypothesis. The paper successively considers a simple non-noisy N -dimensional model, standard models with "intrinsic" uncertainty, and reference intertemporal models with infinite horizon. It reviews existing results and suggests new ones. It translates the formal results into looser but economically intuitive statements, whose robustness, in the present state of knowledge, is tentatively ascertained. [source] A new method to discriminate between a valid IP response and EM coupling effectsGEOPHYSICAL PROSPECTING, Issue 6 2002Jianping Xiang ABSTRACT The problem of discrimination between a valid induced polarization (IP) response and electromagnetic (EM) coupling effects is considered and an effective solution is provided. First, a finite dimensional approximation to the Cole-Cole model is investigated. Using the least-squares approach, the parameters of the approximate model are obtained. Next, based on the analysis of overvoltage, a finite dimensional structure of the IP model is produced. Using this overvoltage-based structure, a specific finite dimensional approximation of the Cole-Cole model is proposed. Summarizing the analysis of the finite dimensional IP model, it is concluded that the proposed IP model, which fits the field data much better than the traditional Cole-Cole model, is essentially an RC-circuit. From a circuit-analysis point of view, it is well known that an electromagnetic effect can be described by an RL-circuit. The simulation results on experimental data support this conception. According to this observation, a new method to discriminate between a valid IP response and EM coupling effects is proposed as follows: (i) use a special finite dimensional model for IP,EM systems; (ii) obtain the parameters for the model using a least-squares approach; (iii) separate RC-type terms and RL-type terms , the first models the IP behaviour, the latter represents the EM part. Simulation on experimental data shows that the method is very simple and effective. [source] Simulating spatially and physiologically structured populationsJOURNAL OF ANIMAL ECOLOGY, Issue 6 2001William S. C. Gurney Summary 1,Population dynamics are frequently the product of a subtle interplay between development and dispersal in an inhomogeneous environment. Simulations of spatially inhomogeneous populations with physiologically distinguishable individuals are a known source of numerical difficulty. 2,This paper reports a new and highly efficient algorithm for this problem, whose accuracy we demonstrate by comparison with conventional numerical solutions of one-dimensional problems. 3,As an illustration, we construct a two (space)-dimensional model of a copepod (Calanus finmarchicus) in the NE Atlantic, and demonstrate that its predictions correspond closely with those of an equivalent Lagrangian ensemble. [source] Synthesis of charged ultrafiltration poly(styrene- co -divinyl benzene) composite membraneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Sonny Sachdeva Abstract A ceramic supported crosslinked polystyrene composite membrane has been prepared from its monomers using a dual initiator system. The nonionic hydrophobic membrane so prepared has been chemically modified by a low temperature (50°C), single step reaction with chloroacetic acid. The carboxylated membrane has acid functional groups on its surface making it negatively charged and highly hydrophilic in nature. The membranes (unmodified and carboxylated) have been used for the separation of hazardous chromium (VI) salt solution where observed and intrinsic rejection has been studied as a function of pressure and concentration of the feed solution. The intrinsic rejection has been determined by calculating the concentration at the membrane surface (Cm) using Speigler-Kedam model and osmotic pressure model. The observed rejection for the chemically modified membrane decreases with increasing pressure but the intrinsic rejection is found to be more than 80% for all concentrations in the range of study. The experimental results have been fitted using Space-Charge model to obtain the membrane wall potential and the membrane surface concentration which are difficult to measure directly. The transport through the membrane capillaries has been described by the two dimensional model using Nernst-Planck equation for ion transport, Navier-Stokes equation and Poisson-Boltzmann equation for the radial distribution of potential. We have then presented a semianalytical series solution to the highly nonlinear Poisson-Boltzmann equation to reduce the computational time required to solve the set of coupled differential equations. The effective wall potential of the carboxylated membrane was found to be ,28.07 mV. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Radiation characteristics of a corrugated horn antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2002Mohammed N. Afsar Abstract A corrugated horn antenna is modeled using the three-dimensional FDTD method. The computed E-plane radiation pattern shows a good agreement with those measured and calculated using the MoM published in the literature. The H-plane radiation pattern and the cross-polarization patterns for both E- and H-plane are also obtained since the corrugated horn is calculated by a three dimensional model. The radiation characteristics for various frequencies have also been analyzed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 83,84, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10379 [source] Comparative gender biases in models of personality disorderPERSONALITY AND MENTAL HEALTH, Issue 1 2009Douglas B. Samuel The potential of gender bias within the DSM personality disorders has long been a concern of scholars and clinicians. Over the past three decades, research findings utilizing the case vignette methodology have repeatedly indicated a gender bias within the histrionic diagnosis. The current study replicates these findings using a novel case vignette, but extends them to investigate the potential for gender biases within an alternative dimensional model of personality,the Five-Factor Model (FFM). One hundred and forty-one practicing clinicians rated either a male or a female version of a case vignette in terms of either the FFM or the personality disorders from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). The results supported the concern of gender bias, with the female case less likely to be diagnosed as antisocial and the male case less likely to be diagnosed as histrionic. However, when the FFM conceptualizations of these two disorders were compared, no significant differences were noted. The results indicate that the FFM may be less prone to gender bias than the current DSM nomenclature. Copyright © 2009 John Wiley & Sons, Ltd. [source] Theory and Numerics of Rate-Dependent Incremental Variational Formulations in FerroelectricityPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008Daniele Rosato This paper is concerned with macroscopic continuous and discrete variational formulations for domain switching effects at small strains, which occur in ferroelectric ceramics. The developed new three,dimensional model is thermodynamically,consistent and determined by two scalar,valued functions: the energy storage function (Helmholtz free energy) and the dissipation function, which is in particular rate,dependent. The constitutive model successfully reproduces the ferroelastic and the ferroelectric hysteresis as well as the butterfly hysteresis for ferroelectric ceramics. The rate,dependent character of the dissipation function allows us also to reproduce the experimentally observed rate dependency of the above mentioned hysteresis phenomena. An important aspect is the numerical implementation of the coupled problem. The discretization of the two,field problem appears, as a consequence of the proposed incremental variational principle, in a symmetric format. The performance of the proposed methods is demonstrated by means of a benchmark problem. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Vibrational Behavior of Bladed Disks in Consideration of Friction Damping and Contact ElasticityPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Christian Siewert Rotating turbine blading is subjected to fluctuating gas forces during operation that cause blade vibrations. One of the main tasks in the design of turbomachinery blading is the reduction of the vibration amplitudes of the blades to avoid high resonance stresses that could damage the blading. The vibration amplitudes of the blades can be reduced significantly to a reasonable amount by means of friction damping devices such as underplatform dampers. In the case of blade vibrations, relative displacements between the friction damping devices and the neighboring blades occur and friction forces are generated that provide additional damping to the structure due to the dry friction energy dissipation. In real turbomachinery applications, spatial blade vibrations caused by a complex blade geometry and distributed excitation forces acting on the airfoil accur. Therefore, a three dimensional model including an appropriate spatial contact model to predict the generalized contact forces is necessary to describe the vibrational behavior of the blading with sufficient accuracy, see [1] and [2]. In this paper the contact model presented in [2] is extended to include also local deformations in the contacts between underplatform dampers and the contact surfaces of the adjacent blades. The additional elasticity in the contact influences the resonance frequency of the coupled bladed disk assembly. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Phonation threshold pressure predictions using viscoelastic properties up to 1,400 Hz of injectables intended for Reinke's space,THE LARYNGOSCOPE, Issue 5 2010Sarah A. Klemuk PhD Abstract Objectives/Hypothesis: Viscoelastic properties of numerous vocal fold injectables have been reported but not at speaking frequencies. For materials intended for Reinke's space, ramifications of property values are of great concern because of their impact on ease of voice onset. Our objectives were: 1) to measure viscoelastic properties of a new nonresorbing carbomer and well-known vocal fold injectables at vocalization frequencies using established and new instrumentation, and 2) to predict phonation threshold pressures using a computer model with intended placement in Reinke's space. Study Design: Rheology and phonation threshold pressure calculations. Methods: Injectables were evaluated with a traditional rotational rheometer and a new piezo-rotary vibrator. Using these data at vocalization frequencies, phonation threshold pressures (PTP) were calculated for each biomaterial, assuming a low dimensional model with supraglottic coupling and adjusted vocal fold length and thickness at each frequency. Results were normalized to a nominal PTP value. Results: Viscoelastic data were acquired at vocalization frequencies as high as 363 to 1,400 Hz for six new carbomer hydrogels, Hylan B, and Extracel intended for vocal fold Reinke's space injection and for Cymetra (lateral injection). Reliability was confirmed with good data overlap when measuring with either rheometer. PTP predictions ranged from 0.001 to 16 times the nominal PTP value of 0.283 kPa. Conclusions: Accurate viscoelastic measurements of vocal fold injectables are now possible at physiologic frequencies. Hylan B, Extracel, and the new carbomer hydrogels should generate easy vocal onset and sustainable vocalization based on their rheologic properties if injected into Reinke's space. Applications may vary depending on desired longevity of implant. Laryngoscope, 2010 [source] Incommensurate structure of Ca2Al2O5 at high temperatures , structure investigation and Raman spectroscopyACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2008Biljana Lazic A high-temperature X-ray diffraction study revealed that brownmillerite-type Ca2Al2O5 transforms to an incommensurately modulated structure at elevated temperatures. Single crystals of Ca2Al2O5 were synthesized in an end-loaded piston cylinder press at 2.5,GPa and 1273,K. The diffraction pattern observed at 1090,(10),K by in situ single-crystal diffraction experiments can be indexed by an I -centred orthorhombic cell and a modulation wavevector of q = 0.595,(1)c*. A (3,+,1)-dimensional model in superspace group Imma(00,)s00 was used to refine the modulated structure. The structure is assembled from two building units: (i) layers of corner-sharing [AlO6] octahedra, stacked along b alternate with (ii) layers of zweier single chains of [AlO4] tetrahedra running along a. The modulated structure arises from an aperiodic sequence of two different configurations of the chains within the tetrahedral layers. The modulated high-temperature phase of Ca2Al2O5 is isotypic to the modulated high-temperature modification of Ca2Fe2O5. A large hysteresis was found in the phase-transition temperature. On heating, the transition occurs at ca 1075,(10),K; on cooling, satellite reflections can be observed down to 975,(10),K. The characterization of Ca2Al2O5 is completed by Raman spectroscopy, including a partial interpretation of the spectra. [source] An Empirically Based Classification of Personality Pathology: Where We Are Now and Where Do We GoCLINICAL PSYCHOLOGY: SCIENCE AND PRACTICE, Issue 2 2007Thomas A. Widiger The review of Sheets and Craighead (2007) affirms the lack of discriminant validity of the Diagnostic and Statistical Manual of Mental Disorders personality disorders, focusing in particular on the three clusters. They call for an empirically based, dimensional classification of personality disorder. Quite a bit of progress toward such an approach has occurred. This commentary emphasizes in particular the importance of having a dimensional model of personality disorder be integrated with general personality structure. [source] | |||||||||||||