Nagalinga Rajan, Soumyendu Raha¹

CMES-Computer Modeling in Engineering & Sciences, Vol.23, No.2, pp. 91-116, 2008, DOI:10.3970/cmes.2008.023.091

Abstract The article describes a numerical method for time domain integration of noisy dynamical systems originating from engineering applications. The models are second order stochastic differential equations (SDE). The stochastic process forcing the dynamics is treated mainly as multiplicative noise involving a Wiener Process in the Itô sense. The developed numerical integration method is a drift implicit strong order 2.0 method. The method has user-selectable numerical dissipation properties that can be useful in dealing with both multiplicative noise and stiffness in a computationally efficient way. A generalized analysis of the method including the multiplicative noise is More >

Thomas Boeck¹, Alexander Nepomnyashchy^2,3, Ilya Simanovskii²

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.1, pp. 11-20, 2008, DOI:10.3970/fdmp.2008.004.011

Abstract Anticonvection in a two-layer system of mercury and water is studied using three-dimensional direct numerical simulations with a Fourier-Chebyshev spectral method. The two fluid layers have equal thicknesses and are uniformly heated from above. Interface deformations and surface tension gradients are neglected. The quiescent state is replaced by steady hexagons upon increasing the heating from above. We investigate the destabilization of this primary convective pattern in a small and in a large computational domain upon increasing the temperature difference across the two fluid layers. For the large domain the convection cells become disordered at about More >

Walter Gerstle¹, Stewart Silling², David Read³, Vinod Tewary⁴, Richard Lehoucq⁵

CMC-Computers, Materials & Continua, Vol.8, No.2, pp. 75-92, 2008, DOI:10.3970/cmc.2008.008.075

Abstract A theoretical framework, based upon the peridynamic model, is presented for analytical and computational simulation of electromigration. The framework allows four coupled physical processes to be modeled simultaneously: mechanical deformation, heat transfer, electrical potential distribution, and vacancy diffusion. The dynamics of void and crack formation, and hillock and whisker growth can potentially be modeled. The framework can potentially be applied at several modeling scales: atomistic, crystallite, multiple crystallite, and macro. The conceptual simplicity of the model promises to permit many phenomena observed in microchips, including electromigration, thermo-mechanical crack formation, and fatigue crack formation, to be More >

Chein-Shan Liu¹

CMC-Computers, Materials & Continua, Vol.8, No.1, pp. 1-16, 2008, DOI:10.3970/cmc.2008.008.001

Abstract In the present work we study numerical computations of inverse thermal stress problems. The unknown boundary conditions of an elastically deformable heat conducting rod are not given a priori and are not allowed to measure directly, because the boundary may be not accessible to measure. However, an internal measurement of temperature is available. We treat this inverse problem by using a semi-discretization technique, of which the time domain is divided into many sub-intervals and the physical quantities are discretized at these node points of discrete times. Then the resulting ordinary differential equations in the discretized More >

Chein-Shan Liu^1,2

CMC-Computers, Materials & Continua, Vol.7, No.2, pp. 81-96, 2008, DOI:10.3970/cmc.2008.007.081

Abstract We consider an inverse problem for estimating an unknown heat conductivity parameter α(t) in a heat conduction equation T_t(x,t) = α(t)T_xx(x,t) with the aid of an extra measurement of temperature gradient on boundary. Basing on an establishment of the one-step Lie-group elements G(r) and G(l) for the semi-discretization of heat conduction equation in time domain, we can derive algebraic equations from G(r) = G(l). The new method, namely the Lie-group estimation method (LGEM), is examined through numerical examples to convince that it is highly accurate and efficient; the maximum estimation error is smaller than 10^-5 for smooth parameter and More >

Bonvissuto GL¹, CA Busso²

Phyton-International Journal of Experimental Botany, Vol.76, pp. 119-131, 2007, DOI:10.32604/phyton.2007.76.119

Abstract The effects of various temperature combinations and water potentials were determined on the germination of Atriplex lampa Gill. ex Moquin, Larrea divaricata Cav., Leymus erianthus (Phil.) Dubcovsky, Stipa neaei Nees ex Steudel and Poa ligularis Nees ap. Steudel under controlled conditions. The tested hypothesis was that seed germination increases with increasing temperatures and water potentials in A. lampa, L. divaricata, L. erianthus, S. neaei and P. ligularis, and that time to reach 50% of total germination is greater at lower than higher water potentials. PEG 2000 was used to impose water stress conditions. In general, obtained results conducted to accept the posted hyphotesis. More >

Premuzic¹ Z, HE Palmucci¹, J Tamborenea¹, M Nakama²

Phyton-International Journal of Experimental Botany, Vol.76, pp. 103-117, 2007, DOI:10.32604/phyton.2007.76.103

Abstract The addition of chlorine constitutes an economical disinfection method for closed, soil-less systems. Three quantities of sodium hypochlorite (0.55, 5.5 and 11 ppm) were applied to closed, soil-less greenhouse- grown lettuce (Lactuca sativa), to study the effect on its production (fresh weight and dry matter) and some commercial and nutritional quality factors (phytotoxicity, Vitamin C, nitrates). Sodium hypochlorite was weekly added within the nutrient solution, and the chemical properties (pH, EC and chlorides) of the recycled solution were measured. Damage to leaves was evaluated 15 days before harvest. Chlorination produced different effects regarding both production and… More >

Serrano-Bernardo F¹, JL Rosúa¹, M Díaz-Miguel²

Phyton-International Journal of Experimental Botany, Vol.76, pp. 27-38, 2007, DOI:10.32604/phyton.2007.76.027

Abstract The Mediterranean region is considered one of the most important zones worldwide in terms of plant diversity. Sierra Nevada (S Spain) is a unique mountain massif within the high-mountain systems of the Mediterranean. It is of great floristic importance and very rich in endemic species. However, it requires numerous tasks for restoring plant cover due to the constant anthropic degradation, especially because of the ski station located near the second-highest peak of the mountain. One of the restoration efforts consists of trying to reproduce, in the laboratory, the ideal conditions to pre-germinate seeds of some… More >

Rodríguez Rivera M F, LR Sosa, EA Fernández, M I Reale, V Villarreal

Phyton-International Journal of Experimental Botany, Vol.76, pp. 5-17, 2007, DOI:10.32604/phyton.2007.76.005

Abstract We studied the germination capacity of Bulnesia retama seeds to conditions of water stress simulated by PEG6000 at different temperatures. We also evaluated their recovery to water stress conditions. Seeds were collected in San Luis city, Argentina. They were placed in polyethylene bags with different concentrations of PEG6000 to simulate water potentials of 0 (control); -0.25; -0.5; -0.75; -1; -1.25 and -1.5 MPa. Seeds were placed in culture oven without light to three temperatures: 18º, 25º and 32 ºC. Non-germinated seeds were washed and placed again to germinate in distilled water to 25 ºC. We registered… More >

B.C. Heng*, K.J. Vinoth*, K. Lu*, X. Deng*, Z. Ge*, B.H. Bay**, T. Cao*

BIOCELL, Vol.31, No.3, pp. 405-410, 2007, DOI:10.32604/biocell.2007.31.405

Abstract We investigated the effects of prolonged heat shock treatment on human embryonic stem cell (hESC) viability. The hESC viability steadily declined with longer exposure to heat shock treatment (43ºC). After 4 h of exposure to heat shock at 43ºC, only 56.2 ± 1.5% of cells were viable. Viability subsequently declined to 37.0 ± 3.3% and 3.5 ± 0.7% after 8 h and 16 h, respectively of heat shock treatment at 43ºC. Transmission electron micrographs showed that the morphology of the dead/dying cells after heat shock treatment was characteristic of cellular necrosis with an uncondensed chromatin… More >