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Equivalent System (equivalent + system)

Distribution by Scientific Domains
Mathematics and Statistics40%

Selected Abstracts

An investigation of thermoelectric cooling devices for small-scale space conditioning applications in buildings

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2010
Mark Gillott
Abstract This paper presents the study of a thermoelectric cooler (TEC) designed for small-scale space conditioning applications in buildings. A theoretical study was undertaken to find the optimum operating conditions, which were then applied in the laboratory testing work. A TEC unit was assembled and tested under laboratory conditions. Eight pieces of UltraTEC were shown to generate up to 220,W of cooling with a COP of 0.46 under the input current of 4.8,A for each module. Thermo-economical analysis was carried out and results showed that a system with PV panel can compete with an equivalent system without a PV panel when PV costs fall down to or lower than £1.25 per Watt. For the cases without a PV panel, the system with a high level of TEC power input delivered a better performance in terms of the average cooling energy price than that system with a low level of TEC power input after critical interest rate (currently 4%). Copyright © 2009 John Wiley & Sons, Ltd. [source]

Elastic,ideally plastic beams and Prandtl,Ishlinskii hysteresis operators

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 18 2007
Pavel Krej
Abstract The one-dimensional equation for transversal vibrations of an elastoplastic beam is derived from a general three-dimensional system with a single-yield tensorial von Mises plasticity model. It leads after dimensional reduction to a multiyield scalar Prandtl,Ishlinskii hysteresis model whose weight function is explicitly given. The use of Prandtl,Ishlinskii operators in elastoplasticity is thus not just a questionable phenomenological approach, but in fact quite natural. The resulting partial differential equation with hysteresis is transformed into an equivalent system for which the existence and uniqueness of a strong solution is proved. The proof employs techniques from the mathematical theory of hysteresis operators. Copyright © 2007 John Wiley & Sons, Ltd. [source]

On the numerical approach of the enthalpy method for the Stefan problem

NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 4 2004
Khaled Omrani
Abstract In this article an error bound is derived for a piecewise linear finite element approximation of an enthalpy formulation of the Stefan problem; we have analyzed a semidiscrete Galerkin approximation and completely discrete scheme based on the backward Euler method and a linearized scheme is given and its convergence is also proved. A second-order error estimates are derived for the Crank-Nicolson Galerkin method. In the second part, a new class of finite difference schemes is proposed. Our approach is to introduce a new variable and transform the given equation into an equivalent system of equations. Then, we prove that the difference scheme is second order convergent. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2004 [source]

Polyurethanes Based on Castor Oil: Kinetics, Chemical, Mechanical and Thermal Properties

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2008
Elodie Hablot
Abstract Polyurethanes based on vegetable oil were synthesized with castor oil and toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, using dibutyltin dilaurate as a catalyst. The effects of the nature of the diisocyanate on the evolution of the kinetics, as well as the physical and mechanical properties and the thermal stability, of the different synthesized polyurethanes were investigated, and these complement data from the literature on equivalent systems. The polymerization kinetics, degree of swelling and mechanical properties were greatly affected by the diisocyanate nature, whereas the rheological properties and thermal stability were found to be similar for all polyurethanes. [source]

A secreted effector protein (SNE1) from Phytophthora infestans is a broadly acting suppressor of programmed cell death

THE PLANT JOURNAL, Issue 3 2010
Brendan S. Kelley
Summary Evasion or active suppression of host defenses are critical strategies employed by biotrophic phytopathogens and hemibiotrophs whose infection mechanism includes sequential biotrophic and necrotrophic stages. Although defense suppression by secreted effector proteins has been well studied in bacteria, equivalent systems in fungi and oomycetes are poorly understood. We report the characterization of SNE1 (suppressor of necrosis 1), a gene encoding a secreted protein from the hemibiotrophic oomycete Phytophthora infestans that is specifically expressed at the transcriptional level during biotrophic growth within the host plant tomato (Solanum lycopersicum). Using transient expression assays, we show that SNE1 suppresses the action of secreted cell death-inducing effectors from Phytophthora that are expressed during the necrotrophic growth phase, as well as programmed cell death mediated by a range of Avr,R protein interactions. We also report that SNE1 contains predicted NLS motifs and translocates to the plant nucleus in transient expression studies. A conceptual model is presented in which the sequential coordinated secretion of antagonistic effectors by P. infestans first suppresses, but then induces, host cell death, thereby providing a highly regulated means to control the transition from biotrophy to necrotrophy. [source]