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排序方式: 共有268条查询结果,搜索用时 31 毫秒
1.
UCINSKI DARIUSZ; JAI ABDELHAQ EL 《IMA Journal of Mathematical Control and Information》1997,14(2):153-174
In this paper, the concept of weak spreadability is introduced.It constitutes an extension of the idea developed by El Jai& Kassara. In the case of linear distributed systems weconsider quadratic control techniques with a conveniently penalizedcriterion which makes the system weakly spreadable. The approachis outlined for a convectiondiffusion system, and theresults of a numerical study are also included to illustratethe main features of the considered problem. 相似文献
2.
Rafael Caballero Mercedes González Flor M Guerrero Julián Molina Concepción Paralera 《European Journal of Operational Research》2007
In this work we present a multiobjective location routing problem and solve it with a multiobjective metaheuristic procedure. In this type of problem, we have to locate some plants within a set of possible locations to meet the demands of a number of clients with multiple objectives. This type of model is used to solve a problem with real data in the region of Andalusia (Spain). Thus, we study the location of two incineration plants for the disposal of solid animal waste from some preestablished locations in Andalusia, and design the routes to serve the different slaughterhouses in this region. This must be done while taking into account certain economic objectives (start-up, maintenance, and transport costs) and social objectives (social rejection by towns on the truck routes, maximum risk as an equity criterion, and the negative implications for towns close to the plant). 相似文献
3.
V. Berbenni G. Flor A. Marini V. Massarotti R. Riccardi 《Journal of Thermal Analysis and Calorimetry》1988,34(2):457-463
The energetics of the dehydration reaction of single crystal (Na, Na 50%-Li, Li) and ceramic Na beta-aluminas have been studied.From the dependence of the dehydration enthalpy values on the water content it has been deduced that lattice water can be bound in two different ways i.e. by ion-dipole interactions with conducting cations and by hydrogen bonds with spinel block oxygens. As expected, the first one gives binding energies depending on the nature of the monovalent cation (H=84.5 and 59.4 kJ/mol H2O for Li and Na beta-alumina respectively). In contrast, the enthalpy change associated with the second one is identical for the three beta-aluminas (H=15.1 kJ/mol H2O). The ceramic Na beta-alumina undergoes a surface reaction too (with CO2) leading to the formation of carbonates and bicarbonates.
Zusammenfassung Die Energetik der Dehydratisierungsreaktion von Einkristallen von Na-, Na (50%)/Li- und Li- sowie von Na--Aluminiumoxid wurde untersucht. Aus der Abhängigkeit der Dehydratisierungsenthalpie vom Wassergehalt ergibt sich, daß Wasser auf zwei verschiedene Weisen gebunden ist, nämlich durch Ion-Dipol-Wechselwirkung mit leitenden Kationen und durch Wasserstoffbrückenbindungen mit Sauerstoffatomen. Wie zu erwarten war werden für die ersteren von der Natur der einwertigen Kationen abhängige Bindungsenergien (H=84.1 kJ/Mol H2O bzw. 59.4 kJ/Mol H2O für Li- bzw. Na--Alumina) erhalten. Die auf die zweite Wechselwirkung zurückzuführenden Enthalpieänderung ist dagegen für die drei-Aluminiumoxide identisch (H=15.1 kJ/Mol H2O). Das keramische Na--Aluminiumoxid zeigt auch eine Oberflächenreaktion mit CO2, die zur Bildung von Carbonaten und Bicarbonaten führt.
(Na, Na 50%-Li, Li)- -- . , - . , Li — Na-- , , 84.5 59.4 / 2. , - 15.1 / 2. Na- , .相似文献
4.
Larsen BR Astorga-Llorens C Florêncio MH Bettencourt AM 《Journal of chromatography. A》2001,926(1):167-174
With its detection limit well below 30 pg microl(-1) LC-MS-MS has become a sensitive and thus popular analytical technique for organoarsenical compounds. Collision induced dissociation (CID) is a valuable tool for speciation and facilitates a positive identification of the species detected. However, it is not straightforward to understand the fragmentation pathways of organoarsenical compounds when only CID-MS-MS data is available. In the present paper we have investigated multiple mass spectrometry (MSn, n=1, 2, 3, 4, 5, 6) with electrospray CID fragmentation for a number of organoarsenical compounds likely to occur in the environment. The investigated compounds were tetramethylarsonium, trimethylarsinoxide, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, and dimethylarsinoylethanol. By CID of (protonated) organoarsenical cations mostly even-electron fragments are produced after neutral loss processes such as elimination of H2, H2O, CH4, C2H2, C2H4, C2H6, HCHO, CH3OH, C2H5OH, C2H4O, and CH2CO. However, abundant odd-electron fragments are also formed after elimination of radical species. Evidence for reduction of As(V) to As(III) as a driving force in the odd-electron ion formation is obtained. 相似文献
5.
6.
The solid–liquid equilibria of the ternary system H2O–Fe(NO3)3–Co(NO3)2 were studied by using a synthetic method based on conductivity measurements.
Two isotherms were established at 0 and 15 °C, and the stable solid phases which appear are the iron nitrate nonahydrate (Fe(NO3)3·9H2O), the iron nitrate hexahydrate (Fe(NO3)3·6H2O), the cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and the cobalt nitrate trihydrate (Co(NO3)2·3H2O). 相似文献
7.
Lorenzo MalavasiPaolo Ghigna Gaetano ChiodelliGiorgio Maggi Giorgio Flor 《Journal of solid state chemistry》2002,166(1):171-176
The synthesis and structural properties of Mg1−xMn2+xO4, for 0≤x≤1 are described. Complete miscibility in the solid state exists for this system. For the material with the correct stoichiometry, i.e. MgMn2O4, the effect of temperature on the cation distribution was investigated= above 600°C the inversion degree (m) starts increasing. The electrical conductivity shows a small dependence on P(O2) which is consistent with the small oxygen non-stoichiometry determined by means of thermogravimetry. The main contribution to the transport properties arises from the inversion equilibrium. Two distinct conductivity regimes, below and above the inversion threshold, can be assumed to explain the electrical conductivity and thermoelectric power results. 相似文献
8.
Contreras Ricardo R. Fontal Bernardo Bahsas Alí Suárez Trino Reyes Marisela Bellandi Fernando Nava Flor Cancines Pedro 《Transition Metal Chemistry》2004,29(1):51-55
The synthesis of [benzyl-N,N-alkylbis(2-amino-1-cyclopentencarbodithioate)]MII [alkyl = ethene (L2) and propene, (L3) and M = Cu, Ni and Co] complexes and their characterization (u.v.–vis., FT-IR, 1H-n.m.r., mass spectra and cyclic voltametry) are reported. 相似文献
9.
Cristina Tealdi Lorenzo Malavasi Giorgio Flor 《Journal of solid state chemistry》2004,177(11):4359-4367
Atomistic computer simulation techniques have been used, for the first time, to reproduce the crystal structure of MgTa2O6 and to investigate the defect chemistry and dopant properties of this material. The calculated defect energetics suggest that the concentration of intrinsic atomic defects in this phase is insignificant and that the system is probably stable to both oxidation and reduction. Dopant solution energy versus ion size trends are found for both isovalent and aliovalent dopant incorporation at Mg and Ta sites. Divalent dopants (e.g. Ca, Cu) preferentially occupy the Mg site whereas dopants with higher charge (e.g. Sc, Zr, Nb) are more favorable on the Ta site. High migration activation energies (>2 eV) predict limited ionic conductivity in this material. 相似文献
10.