Information Preservation Modeling of Rayleigh-Benard Transition from Thermal Conduction to Convection

Onset and evolution of the Rayleigh-Benard (R-B) convection are investigated using the Information Preservation (IP) method. The information velocity and temperature are updated using the Octant Flux Splitting (OFS) model developed by Masters & Ye based on the Maxwell transport equation suggested by Sun & Boyd. Statistical noise inherent in particle approaches such as the direct simulation Monte Carlo (DSMC) method is effectively reduced by the IP method, and therefore the evolutions from an initial quiescent fluid to a final steady state are shown clearly. An interesting phenomenon is observed: when the Rayleigh number (Ra) exceeds its critical value, there exists an obvious incubation stage. During the incubation stage, the vortex structure clearly appears and evolves, whereas the Nusselt number (Nu) of the lower plate is close to unity. After the incubation stage, the vortex velocity and Nu rapidly increase, and the flow field quickly reaches a steady, convective state. A relation of Nu to Ra given by IP agrees with those given by DSMC, the classical theory and experimental data.

固体力学进展及应用: 庆贺李敏华院士90华诞文集

《固体力学进展及应用：庆贺李敏华院士90华诞文集》收录了近代固体力学基础理论及其应用领域的重要科技成果和最新进展。作者是在同体力学领域工作多年的资深研究员，他们来自各行各业，有丰富的科研与丁作经验。他们提供的论文在相当程度上反映当前同体力学的发展现状与成就，并能看出发展趋势，对未来研究的课题选择有参考价值。《固体力学进展及应用：庆贺李敏华院士90华诞文集》还收集了李敏华院士的珍贵照片和纪念李敏华院士90华诞的庆贺和回忆文章，具有重要的史料价值。

The potential impact of Ocean Thermal Energy Conversion (OTEC) on fisheries

The commercial development of ocean thermal energy conversion (OTEC) operations will involve some environmental perturbations for which there is no precedent experience. The pumping of very large volumes of warm surface water and cold deep water and its subsequent discharge will result in the impingement, entrainment, and redistribution of biota. Additional stresses to biota will be caused by biocide usage and temperature depressions. However, the artificial upwelling of nutrients associated with the pumping of cold deep water, and the artificial reef created by an OTEC plant may have positive effects on the local environment. Although more detailed information is needed to assess the net effect of an OTEC operation on fisheries, certain assumptions and calculations are made supporting the conclusion that the potential risk to fisheries is not significant enough to deter the early development of IDEe. It will be necessary to monitor a commercial-scale plant in order to remove many of the remaining uncertainties. (PDF file contains 39 pages.)

Sea surface temperature and the distribution and apparent abundance of skipjack (Katsuwonus pelamis) in the Eastern Pacific Ocean, 1951-1968

ENGLISH: Isograms of sea surface temperature (OC) have been produced for 1949-1968 for the areas of the eastern Pacific Ocean in which the majority of the skipjack catch is taken. These are in the immediate coastal zone, California (35° N) to Chile (20 0 S), and the Revillagigedo and Galapagos Islands groups. Skipjack occurrence and apparent abundance (as CSDF, i.e., catch per standard days fishing, standardized in purse-seiner units) for 1951-1968 were then superimposed on the surface temperature isograms. Results show that skipjack occur at surface temperatures> 17° C but with the majority between 20°-30° C. Apparent abundance at CSDF > 1 ton/day is normally Iimited to 20°29° C water, except in two areas in certain years; from the Gulf of Tehuantepec to Cape Mala rates of 1-9 tons/day are relatively common at 29°-30° C, and off Chimbote (Peru) occasionally >9 tons/day are recorded down to 18° C. As expected there were no apparent relationships between annual thermal conditions in the coastal zone and skipjack abundance (total catch or indices of abundance) in the same or 2 subsequent years. An Appendix to the report determines the quantitative relationships between surface temperature and skipjack abundance in relatively small areal strata in Baja California waters in 1955 and 1958. Relationships generally appeared significant and opposite in these years when temperatures were respectively anomalously cold and warm. SPANISH: Se han producido isogramas de la temperatura de la superficie del mar (OC) para 1949-1968 correspondientes a las áreas del Océano Pacífico oriental en donde se obtiene la mayor parte de la captura de barrilete. Estas se encuentran ubicadas en la zona costanera inmediata, desde California (35°N) hasta Chile (200S) y en las Islas Revillagigedo y Galápagos. La ocurrencia de barrilete y su abundancia aparente (expresada como CDSP standardizada en unidades de cerqueros) para 1951-1968 fueron luego superpuestas en los isogramas de la temperatura superficial. Los resultados demuestran que el barrilete aparece en temperaturas superficiales de > 17°C pero la mayoría entre los 20°C-30°C. La abundancia aparente de la CDSP > 1 tonelada/día se limita normalmente a aguas de 20°-29°C, excepto en dos áreas en ciertos años; desde el Golfo de Tehuantepec a Cabo Mala las tasas de 1-9 toneladas/día son relativamente comunes en los 29°-30°C, y frente a Chimbote (Perú) se registran ocasionalmente> 9 toneladas/día a una temperatura tan fría como de 18°C. Como era de esperarse no existió una relación aparente entre las condiciones térmicas anuales de la zona costanera y la abundancia del barrilete (captura total o índices de abundancia) en el mismo año o en los 2 años siguientes. Un Apéndice del informe determina la relación cuantitativa entre la temperatura superficial y la abundancia del barrilete en un estrato de áreas relativamente pequeño en las aguas de Baja California en 1955 y 1968. Las relaciones generalmente aparecieron significativas y opuestas en esos años cuando las temperaturas fueron respectivamente anómalamente frías y calientes. (PDF contains 53 pages.)

Size- And Temperature-Dependent Thermal Expansion Coefficient Of A Nanofilm

The thermal expansion coefficient (TEC) of an ideal crystal is derived by using a method of Boltzmann statistics. The Morse potential energy function is adopted to show the dependence of the TEC on the temperature. By taking the effects of the surface relaxation and the surface energy into consideration, the dimensionless TEC of a nanofilm is derived. It is shown that with decreasing thickness, the TEC can increase or decrease, depending on the surface relaxation of the nanofilm.

Mechanisms of thermal shock failure for ultra-high temperature ceramic

The materials considered in our analysis were ZrB2 ceramic matrix composites. Effect of two different additives (graphite and AlN) on thermal shock stability for the materials was measured by water quench test. It showed that it may provide more stable thermal shock properties with additives of graphite. It was explained by different thermal properties and crack resistance of the two materials in detail. Surface oxidation was one of main reasons for strength degradation of ceramic with additives of graphite after quenched in water, and surface crack was one of main reasons for strength degradation of ceramic with additives of AlN after quenched in water. It was presented that it was a potential method for improving thermal shock stability of ZrB2 ceramic matrix composites by introducing proper quantities of graphite.

Catch rates as indices of abundance of yellowfin tuna, Thunnus albacares, in the Eastern Pacific Ocean

ENGLISH: Catch and effort data from logbooks of tuna seiners were used to make estimates of catch per hour of searching for 1970-1980. The estimates were standardized using a regression model to make annual estimates of abundance adjusted for fishing mode, speed, capacity, use of aerial assistance, net dimensions, and sea-surface temperature. Inside the CYRA the standardized estimates for tuna schools associated with dolphins and those for schools not associated with dolphins showed a similar overall pattern of decline. The 1980 catch rates were about 300/0 of the 1970 rates, the decline being greater for the schools not associated with dolphins. Dolphin-associated schools outside the CYRA declined to about 60% of the 1970 levels. SPANISH: Se emplearon los datos de la captura y el esfuerzo de los cuadernos de bitácora de las embarcaciones cerqueras para hacer las estimaciones de la captura por hora de búsqueda correspondientes a 1970-1980. Se normalizaron estas estimaciones usando un modelo de regresión con el fin' de hacer las estimaciones anuales de la abundancia, ajustadas según la moda de pesca, velocidad, capacidad, uso de ayuda aérea, dimensiones de la red y temperatura de la superficie del mar. En el ARCAA las estimaciones normalizadas de los cardúmenes de atún asociados con delfines y aquellas de los cardúmenes no asociados con delfines, indicaron una pauta general similar de reducción. Las proporciones de captura de 1980, fueron cerca del 300/0 de las de 1970, encontrándose la mayor reducción en los cardúmenes no asociados con delfines. Los cardúmenes asociados con delfines, fuera del ARCAA, se redujeron en un 60% con respecto a los niveles de 1970. (PDF contains 79 pages.)