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Analytic Results (analytic + result)
Selected AbstractsFormulation of Boundary Conditions for the Unmagnetized Multi-Ion-Component Plasma SheathCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7-9 2006D. Tskhakaya Abstract Boundary conditions are derived for the unmagnetized electrostatic multi-ion-component plasma sheath. Analytic results are supported by high-resolution numerical kinetic (particle-in-cell) simulations. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microcellular model evaluation for the deformation of dynamically vulcanized EPDM/iPP blendsPOLYMER ENGINEERING & SCIENCE, Issue 3 2003Kathryn J. Wright The origins of elasticity in thermoplastic vulcanizates have been debated for the past decade. Previous modeling attempts provide numerical solutions that make assessment of constituent concentration and interaction unclear. A microcellular modeling approach is proposed and evaluated herein to describe the steady-state behavior of dynamically vulcanized blends of ethylene-propylene-diene monomer (EPDM) and isotactic polypropylene (iPP). This approach provides an analytic result including terms for composition and cure state. Three types of deformation are accounted for: elastic and plastic deformation of iPP, elastic deformation of EPDM, and localized elastic and plastic rotation about iPP junction points. The viability of the constitutive model is evaluated in terms of iPP concentration and EPDM cure state. [source] Estimation of the Investment Thresholds of Large Japanese ManufacturersTHE JAPANESE ECONOMIC REVIEW, Issue 4 2000Yuzo Honda We approximate the investment threshold by the point at which a logistic curve has the largest curvature of convexity. Our threshold estimates are 1.82 and 1.51 in Tobin's marginal Q for machinery manufacturers and chemical/metal manufacturers, respectively. These numbers lie in between the two estimates calculated by Barnett and Sakellaris for US manufacturers. Our estimates exceed one in all industries, which also agrees with Dixit and Pindyck's analytic result. The threshold for the electrical machinery industry is higher than the others. An increase in uncertainty raises the investment threshold, while an appreciation in asset value lowers it. JEL Classification Numbers: C23, E22. [source] Studies on PNPP Hydrolysis Catalyzed by Schiff Base Cobalt(II) ComplexesCHINESE JOURNAL OF CHEMISTRY, Issue 11 2006Qin Xiao Abstract Two cobalt(II) complexes of the Schiff base with morpholino or aza-crown ether pendants, CoL1 and CoL2, as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester (PNPP). The analysis of specific absorption spectra of the hydrolytic reaction systems indicates that key intermediates, made up of PNPP and Co(II) complexes, have been formed in reaction processes of the PNPP catalytic hydrolysis. The mechanism of PNPP catalytic hydrolysis has been proposed based on the analytic result of specific absorption spectrum. A kinetic mathematical model, applied to the calculation of the kinetic parameter of PNPP catalytic hydrolysis, has been established based on the mechanism proposed. The acid effect of buffer solution, structural effect of the complexes, and effect of temperature on the rate of PNPP hydrolysis catalyzed by the complexes have been also discussed. [source] TLM models of waves in moving media: refinements and dispersion analysisINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 5 2003William J O'Connor Abstract Two recent papers about transmission line matrix (TLM) models of waves in moving media used notional diodes to achieve the appropriate direction-dependent wave speeds. Despite the algorithm's demonstrated success, the operation of the diodes might be criticized for being non-physical from a circuit theory perspective. Alternative circuit models are here developed that avoid this objection, being based on wave two-ports and standard circuit theory components. Their operation obeys the same numerical algorithm derived using the diodes, thereby confirming the validity of the original computational scheme. Furthermore these circuits lead more easily to the direction-dependent wave speed expressions and provide exact analytic results for dispersion and attenuation effects, which are here presented and discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Performance of block-coded land mobile satellite systemsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2008Chang-Ming Lee Abstract Although various measurements have indicated that mobile satellite channels are not memoryless, most related coded system performance analysis assumes perfect interleaving is in place so that the effect of channel memory can be completely ignored. This paper presents a systematic method to accurately and efficiently predict the performance of errors-and-erasures or errors-only decoders for block-coded systems in general mobile satellite channels. Numerical results are provided to validate our analytic results. Copyright © 2008 John Wiley & Sons, Ltd. [source] Pitfalls of Ability ResearchINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 4 2001Thomas R. Carretta Ability research in psychology can be fraught with pitfalls that lead to inappropriate conclusions. We identify several issues that lead to potential misinterpretation of results and suggest corrective solutions. These issues include lack of construct validity of the measures, misinterpretation of correlations and regression weights, lack of statistical power, failure to estimate cross-validation effects, and misinterpretation of factor analytic results. [source] Soliton propagation in an absorbing three-level atomic systemLASER PHYSICS LETTERS, Issue 8 2004H. Eleuch Abstract We present analytic results of soliton shapes propagating in an absorbing three-level atomic system in the lambda configuration which is excited by a CWfield at the Stokes transition. We find analytic relations for the control of the propagation velocity which can be influenced by the pulse width and by the intensity and polarization of the CW field. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] The evolution of substructure in galaxy, group and cluster haloes , III.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2005Comparison with simulations ABSTRACT In a previous paper, we described a new method for including detailed information about substructure in semi-analytic models of halo formation based on merger trees. In this paper, we compare the predictions of our model with results from self-consistent numerical simulations. We find that in general the two methods agree extremely well, particularly once numerical effects and selection effects in the choice of haloes are taken into account. As expected from the original analyses of the simulations, we see some evidence for artificial overmerging in the innermost regions of the simulated haloes, either because substructure is being disrupted artificially or because the group-finding algorithms used to identify substructure are not detecting all the bound clumps in the highest-density regions. Our analytic results suggest that greater mass and force resolution may be required before numerical overmerging becomes negligible in all current applications. We discuss the implications of this result for observational and experimental tests of halo substructure, such as the analysis of discrepant magnification ratios in strongly lensed systems, terrestrial experiments to detect dark matter particles directly or indirect detection experiments searching for positrons, gamma-rays, neutrinos or other dark matter decay or annihilation products. [source] Market risk and process uncertainty in production operationsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 7 2006Bardia Kamrad Abstract By adopting a real options framework we develop a production control model that jointly incorporates process and market uncertainties. In this model, process uncertainty is defined by random fluctuations in the outputs' yield and market risk through demand uncertainty for the output. In our approach, production outputs represent commodities or items for which financial contracts do not trade. Outputs are also functionally linked to the level of input inventories. To extend the model's applicability to a wide range of production industries, inputs are modeled to reflect either renewable or partially renewable or non-renewable resources. Given this setting, techniques of stochastic control theory are employed to obtain value maximizing production policies in a constrained capacity environment. The rate of production is modeled as an adapted positive real-valued process and analogously evaluated as a sequence of complex real options. Since optimal adjustments to the rate of production also functionally depend on the outputs' yield, we optimally establish "trigger boundaries" justifying controlled variations to the rate of production over time. In this context, we provide closed form analytic results and demonstrate their robustness with respect to the stochastic (including mean reverting) processes considered. Using these results, we also demonstrate that the value (net of holding costs) accrued to the producer from having an inventory of the output is equivalent to the producer's reservation price to operationally curb its process yield. These generalizations extend the scope of model applicability and provide a basis for applying the real options methodology in the operations arena. The model is explored numerically using a stylized example that allows for both output and demand uncertainty and achieves greater realism by incorporating an element of smoothing into the sequence of production decisions. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006 [source] Inflation of Type I error rate in multiple regression when independent variables are measured with errorTHE CANADIAN JOURNAL OF STATISTICS, Issue 1 2009Jerry Brunner MSC 2000: Primary 62J99; secondary 62H15 Abstract When independent variables are measured with error, ordinary least squares regression can yield parameter estimates that are biased and inconsistent. This article documents an inflation of Type I error rate that can also occur. In addition to analytic results, a large-scale Monte Carlo study shows unacceptably high Type I error rates under circumstances that could easily be encountered in practice. A set of smaller-scale simulations indicate that the problem applies to various types of regression and various types of measurement error. The Canadian Journal of Statistics 37: 33-46; 2009 © 2009 Statistical Society of Canada Lorsque les variables indépendantes sont mesurées avec erreur, la régression des moindres carrés ordinaires peut conduire à une estimation biaisée et incohérente des paramètres. Cet article montre qu'un accroissement de l'erreur de type I peut aussi se produire. En plus de résultats analytiques, une étude par simulations Monte-Carlo de grande envergure montre que, dans certaines conditions que nous pouvons rencontrer facilement en pratique, l'erreur de type I peut être trop élevée. Une autre étude de Monte-Carlo de moindre envergure suggère que ce problème se rencontre aussi dans plusieurs types de régression et différents types d'erreur de mesure. La revue canadienne de statistique 37: 33-46; 2009 © 2009 Société statistique du Canada [source] 1/f noise and slow relaxations in glassesANNALEN DER PHYSIK, Issue 12 2009A. Amir Abstract Recently we have shown that slow relaxations in the electron glass system can be understood in terms of the spectrum of a matrix describing the relaxation of the system close to a metastable state. The model focused on the electron glass system, but its generality was demonstrated on various other examples. Here, we study the noise spectrum in the same framework. We obtain a remarkable relation between the spectrum of relaxation rates , described by the distribution function P (,) , 1/, and the 1/f noise in the fluctuating occupancies of the localized electronic sites. This noise can be observed using local capacitance measurements. We confirm our analytic results using numerics, and also show how the Onsager symmetry is fulfilled in the system. [source] | |||||||||||||||||||