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1.
Christian P. Romero Jonathan I. Avila Edgardo Cisternas Guerau B. Cabrera Alejandro L. Cabrera Kristiaan Temst Margriet J. Van Bael 《Journal of Materials Science》2007,42(18):7667-7672
Hydrogen desorption curves were obtained from a sample composed of a square arrangement of Co dots with average diameter of
4.4 μm, separated by a distance of 11.6 μm. A macroscopic sample of Co dots grown on a 2.5 × 2.5 cm Si substrate was made
by standard lithographic techniques and used in these experiments. Thermal programmed desorption (TPD) was performed under
ultra-high vacuum conditions. Hydrogen TPD curves were obtained from a 1 × 1 cm Co dots samples displaying a maximum of intensity
at 425 K. Hydrogen TPD curve was also obtained from 1 cm× 1 cm samples of Co films and Co foils for comparison. The hydrogen
TPD curves have decreasing intensity from the Co foils to the Co dots and finally to the Co films. This indicates that there
are more sites for hydrogen adsorption on the Co dots than in the Co films. This is a surprising result because there is approximately
8.7 times less Co atoms exposed in the Co dots that in the Co film sample. A desorption energy of 27 kcal/mol was obtained
for the Co dots suggesting that hydrogen is adsorbed on an hcp hollow site of the Co dot crystalline structure. 相似文献
2.
3.
In this article, we analyze a co-operative multi-thread search-based optimization strategy, where each solver thread represents a different optimization algorithm (or the same one with different settings), and they are all controlled by a centralized co-ordinator. We also propose the use of memory to keep track of both the state of the individual threads and the obtained solutions. Based on this memory, a very simple fuzzy rule base is used to control the system behavior.We also present the results of three computational experiments. The first of these checks the strategy by comparing it with an independent search strategy and a sequential algorithm, and the superiority of the co-operative scheme is confirmed. The second analyzes how definition of the threads affects the quality of the results, and the importance of there being a balanced set between intensification and diversification is corroborated. The third explores the use of memory with two different fuzzy rules, and the results indicate that the best combination is to use memory together with two rules (solver dependent and solver independent ones) (although this combination should not be activated at the beginning of the search in order to avoid premature convergence). 相似文献
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5.
The Grid shows itself as a globally distributed computing environment, in which hardware and software resources are virtualized to transparently provide applications with vast capabilities. Just like the electrical power grid, the Grid aims at offering a powerful yet easy‐to‐use computing infrastructure to which applications can be easily ‘plugged’ and efficiently executed. Unfortunately, it is still very difficult to Grid‐enable applications, since current tools force users to take into account many details when adapting applications to run on the Grid. In this paper, we survey some of the recent efforts in providing tools for easy gridification of applications and propose several taxonomies to identify approaches followed in the materialization of such tools. We conclude this paper by describing common features among the proposed approaches, and by pointing out open issues and future directions in the research and development of gridification methods. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
6.
LF Callado JJ Meana B Grijalba A Pazos M Sastre JA García-Sevilla 《Canadian Metallurgical Quarterly》1998,70(3):1114-1123
The alpha2A- and alpha2C-adrenoceptor subtypes were evaluated in postmortem brains from suicides with depression (n = 22), suicides with other diagnoses (n = 12), and controls (n = 26). Membrane assays with the antagonist [3H]RX821002 (2-[3H]methoxyidazoxan) suggested the presence of alpha2A-adrenoceptors in the frontal cortex and both alpha2C-adrenoceptors and alpha2A-adrenoceptors in the caudate. The proportions in caudate were similar in controls (alpha2A, 86%; alpha2C, 14%), depressed suicides (alpha2A, 91%; alpha2C, 9%), and suicides with other diagnoses (alpha2A, 88%; alpha2C, 12%). Autoradiography of [3H]RX821002 binding under alpha(2B/C)-adrenoceptor-masking conditions confirmed the similar densities of alpha2A-adrenoceptors in the cortex, hippocampus, and striatum from controls and suicides. In the frontal cortex of depressed suicides, competition of [3H]RX821002 binding by (-)-adrenaline revealed a greater proportion (61 +/- 9%) of alpha2A-adrenoceptors in the high-affinity conformation for agonists than in controls (39 +/- 5%). Simultaneous analysis with the agonists [3H]clonidine and [3H]UK14304 and the antagonist [3H]RX821002 in the same depressed suicides confirmed the enhanced alpha2A-adrenoceptor density when evaluated by agonist, but not by antagonist, radioligands. The results indicate that depression is associated with a selective increase in the high-affinity conformation of the brain alpha2A-adrenoceptors. 相似文献
7.
Thermodynamic principles, involving mainly: (1) minimum reversible work of separation and (2) second-law analysis that accounts for irreversibility, are used to synthesize separation trains. These principles lead to a development and classification into two groups of many of the heuristics appearing in the literature. An efficient algorithm based on reversible thermodynamics leads to optimal structures for simple acyclic trains. Complex structures are efficiently synthesized by algorithms using reversible thermodynamics and second-law analysis. The procedures presented are depth-first algorithms. The optimal structures developed are shown to be strongly influenced by feed and product compositions. 相似文献
8.
Ralquí Garcia Gustavo Gedler Alejandro Izquierdo Douglas Rodriguez 《Petroleum Science and Technology》1994,12(7):983-1001
This paper describes the statistical analysis of data on coke formation (measured by microcarbon residue) in five resids, as a function of compound classes, in order to identify variables wiih a significant effect on the former. In this sense, the SAS VARCLUS and Principal Component Analysis were used. The analysis carried out leads to a lineal combination of the H/C ratio, vanadium and nitrogen content as a model to explain coke yield, under non-catalytic conditions, as determined by MCR. Of all these factors, the H/C ratio has the most important contribution. 相似文献
9.
Alejandro F. Villaverde Cesáreo Raimúndez Antonio Barreiro 《International Journal of Control, Automation and Systems》2012,10(1):78-87
Crane operation is a challenging task, due to the combined problem of obstacle avoidance and load swing suppression in underactuated
conditions. This paper presents a human-machine interface that increases the operator’s perception of a gantry crane’s workspace.
With this aim, a virtual environment resembling the workspace is connected with a haptic device. This allows the user to receive
not only visual but also tactile feedback, thus increasing maneuvering safety. Additionally, this capability is integrated
in a teleoperation setup, adopting a passivity-based control approach that guarantees overall stability. This includes also
the design of controllers by means of the IDA-PBC method. Experimental results carried out with a laboratory crane show its
feasibility for internet-based teleoperation and demonstrate the improvements on the system performance. 相似文献
10.
Tomasz Z. Tomkiewicz Nuria Surez-Herrera Frans P. M. Cremers Rob W. J. Collin Alejandro Garanto 《International journal of molecular sciences》2021,22(9)
The discovery of novel intronic variants in the ABCA4 locus has contributed significantly to solving the missing heritability in Stargardt disease (STGD1). The increasing number of variants affecting pre-mRNA splicing makes ABCA4 a suitable candidate for antisense oligonucleotide (AON)-based splicing modulation therapies. In this study, AON-based splicing modulation was assessed for 15 recently described intronic variants (three near-exon and 12 deep-intronic variants). In total, 26 AONs were designed and tested in vitro using a midigene-based splice system. Overall, partial or complete splicing correction was observed for two variants causing exon elongation and all variants causing pseudoexon inclusion. Together, our results confirm the high potential of AONs for the development of future RNA therapies to correct splicing defects causing STGD1. 相似文献