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991.
The need to have reliable foundations for potentially vulnerable installations like nuclear power stations has renewed interest in a particularly hazardous phenomenon of some earthquakes. This is when a saturated level sandy soil can behave almost like a liquid as a result of the severe ground motion. A new approach to determining this liquefaction potential, using cyclic strain-controlled tests, is presented in this article from the USA. 相似文献
992.
Torn Fusegi Jae Min Hyun Kunio Kuwahara 《Numerical Heat Transfer, Part A: Applications》2013,63(2):215-229
A high-resolution, finite-difference numerical study is reported on natural convection in a square cavity. The vertical sidewatts of the cavity are differentially heated, and a uniform internal heat generation is also present. Two principal parameters are considered, the internal Rayleigh number RaI, which represents the strength of the internal heat generation, and the external Rayleigh number Rag, which denotes the effect due to the differential heating of the side walls. The internal Rayleigh number varies in the range 1010 RaI ≤ 107, while the external Rayleigh number is set at RaE = 5 x 107 for most computations. As the relative strength of the internal heat generation increases, the flows near the tap portion of the heated sidewall are directed downward. When the effect of the internal heat generation is dominant, the thermal energy leaves the system for the surroundings over the top portion of the heated wall. Only in the bottom pari of the heated wall is heat transfer directed into the system. These numerical solutions are in qualitative agreement with the available experimental measurements. 相似文献
993.
Electrical resistance measurement is effective for monitoring damage (due to damage infliction and subsequent microcrack opening) and healing (due to microcrack closing) of cement pastes (plain, with silica-fume, and with latex) in real time during repeated compressive loading. Damage causes the resistance to increase; healing causes the resistance to decrease. 相似文献
994.
Abstract The multiple‐target tracking (MTT) algorithm plays an important role in radar systems. Data association is the most important technique to solve the tracking problems associating dense measurements with existing tracks. A new approach applying Likelihood to measurements and existing tracks in a radar system based on Neural Network computation is investigated in this paper. The proposed algorithm will solve both the data association and the target tracking problems simultaneously. With this approach, the matching between radar measurements and existing target tracks can achieve global relevance. Computer simulation results indicate the ability of this algorithm to keep track of targets under various conditions. 相似文献
995.
996.
Extended Gaussian image (EGI) and complex EGI (CEGI) have been widely used as the representation of 3D shapes for shape recognition
and pose estimation. In this work, we extend the representations and present a new representation named enriched complex extended
Gaussian image (EC-EGI). The representation follows the same framework of EGI and CEGI, which is to represent each surface
patch of the target 3D shape as a weight at the associated spot on the surface of the Gaussian sphere. However, while the
original CEGI uses a single complex number as the weight, the new representation uses three complex numbers, which are related
to the centroid position of the surface patch in 3D. With the inclusion of more information in the new representation, not
only could object pose be determined more accurately, but also some key ambiguities of shape representation that CEGI and
EGI have also removed. The translation parameters in the pose estimation application could also be determined in a simpler
and more accurate way. In addition, the Gaussian sphere partition problem of CEGI is no longer present. Experimental results
on synthetic and real image data are shown to illustrate the performance of the proposed representation in pose estimation. 相似文献
997.
Hyun Jin Ryu Kyeong Keun Oh Young Soo Kim 《Journal of Industrial and Engineering Chemistry》2009,15(4):471-475
Microalgae fix CO2 as energy source and afford biomass and high valued products such as carotenoids, pigments, proteins, and vitamins that can be used for the production of nutraceuticals, pharmaceuticals, animal feed additives, cosmetics, etc. Carbon dioxide is the sole source of carbon and it is supplied continuously for the microalgal cultivation. But undissolved CO2 is lost by outgassing and sufficient dissolved CO2 should be provided to avoid carbon limitation. The effect of CO2 mass transfer with different CO2 concentrations, aeration rate of gas, bubble size, baffle type and baffle number on the growth of Chlorella sp. AG10002 was investigated and the optimized conditions for the enhancement of biomass productivity were determined. We confirm that these results can be provided as basic data to improve the CO2 mass transfer ability for the high density culture of Chlorella sp. and some microalgae having commercial value. 相似文献
998.
Polyurethane foams were prepared using starch as a main component of polyols and their structural, mechanical, and absorbing properties for organic solvents were investigated. Fourier transform infrared spectra showed that urethane linkage was formed by the reactions between ? NCO of diisocyanates and ? OH of polyols. When polyurethane foams were prepared at high molar ratio of ? NCO/? OH, the unreacted ? NCO groups were detected. Also, urea linkage was formed by the reaction between diisocyanate and water, which was used as the foaming agent. The micrographs showed that the polyurethane foams had closed‐cell structure, of which the cell size increased with ? NCO/? OH molar ratio. The density of polyurethane foams increased with molecular weight of polyethylene glycol. The compressive moduli of polyurethane foams increased with ? NCO/? OH molar ratio. Polyurethane foams prepared using toluene‐2,4‐diisocyanate as diisocyanate had the highest modulus, while those prepared using hexamethylene diisocyanate had the lowest modulus. In case of the absorbency for the organic solvents, the polyurethane foams prepared at ? NCO/? OH molar ratio of 0.8 had the maximum absorbency. Among several organic solvents, the absorbency for dimethyl sulfoxide was the highest, while the absorbency for tetrahydrofuran was the lowest. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1544–1553, 2007 相似文献
999.
The control of unexpectedly rapid Li intercalation reactions without structural instability in olivine‐type LiFePO4 nanocrystals is one of the notable scientific advances and new findings attained in materials physics and chemistry during the past decade. A variety of scientific studies and technological investigations have been carried out with LiFePO4 to elucidate the origins of many peculiar physical aspects as well as to develop more effective synthetic processing techniques for better electrochemical performances. Among the several features of LiFePO4 that have attracted much interest, in this article we address four important issues—regarding doping of aliovalent cations, distribution of Fe‐rich secondary metallic phases, nanoparticle formation during crystallization, and antisite Li/Fe partitioning—by means of straightforward atomic‐scale imaging and chemical probing. The direct observations in the present study provide significant insight into alternative efficient approaches to obtain conductive LiFePO4 nanocrystals with controlled defect structures. 相似文献
1000.
Shalabh C. Maroo J.N. Chung 《International Journal of Heat and Mass Transfer》2010,53(15-16):3335-3345
A nanoscale evaporating meniscus is simulated in this work using molecular dynamics. The heat and mass transfer characteristics and pressure variation in the non-evaporating and interline regions are studied. Very high heat and evaporation flux rates of the order of 100 MW/m2 and 1000 kg/m2 s, respectively, are achieved. The disjoining pressure increased significantly after the formation of the non-evaporating film. High negative liquid pressure induced due to capillary and disjoining pressures are obtained. Cavitation cannot occur as the film thickness is smaller than the critical cavitation radius, and the meniscus can exist in metastable state. A curve-fitted meniscus boundary condition is developed; a force function of the form Fn = An?3 ? Cn?2 can be applied at the boundaries of a liquid film to create curvature and form a meniscus. 相似文献