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631.
We model the working of a civil engineering firm concerned with land development as a three stage flexible flowshop with weak chain precedence constraints and where preemption is allowed. The scheduling objective is to minimize the total tardiness for all the projects. Since solving this problem optimally is very hard, we propose a number of heuristic scheduling procedures which are evaluated extensively on real-life data and artificial problem instances. 相似文献
632.
Moshe Dayan 《Surface science》1985,149(1):L33-L38
633.
634.
We present a simple derivation of classes of early-time solutions of the Smoluchowski equation in the presence of boundaries, simplifying and generalizing an analysis by van Kampen. 相似文献
635.
Moshe Rosenfeld 《Journal of Combinatorial Theory, Series B》1982,33(2):191-195
A triangle free graph which cannot be embedded in a unit sphere is constructed. The construction uses the powerful orthogonal representation of graphs due to Lovász, and exhibits a strong connection between embeddability and Ramsey numbers. We also show that for every ε > 0 there is a triangle free graph Gε that is not embeddable, thus settling Larman's conjecture. 相似文献
636.
For finite field extensions of the field of Henselian p-adic rational numbers necessary and sufficient conditions are given which state that the fields have isomorphic absolute Galois groups; it is thereby supposed that a p-th root of unity (a 4-th when p = 2) belongs to the fields. Also examples are discussed. 相似文献
637.
The conditions for obtaining stable dispersions of 10-μ droplets of monomer in an aqueous phase using steric and electrostatic stabilizers, were studied. The nature and concentration of the surfactant in the aqueous phase has an important effect on the size of the droplets and the stability of the dispersion during the polymerization reaction. The amount of polyvinylalcohol adsorbed on the interface was measured and the rate of desorption was shown to be very slow. It was also shown that sodium dodecyl sulfate, on the other hand, is more readily desorbed. These findings have an effect on the amount of the submicron emulsion particles formed during the polymerization process. 相似文献
638.
Summary A natural definition of the Markov property for multi-parameter random processes (random fields) is the following. Let {X
t,t
N
} be a multiparameter process. For any set D in N let
D
denote the -field generated by {X
t
, tD}. The field {X
t,tD} is said to be Markov (or Markov of degree 1 [6], or sharp Markov) if, for any bounded open set D with smooth boundary,
D
and
D
c are conditionally independent given
D
. It has been known for some time that to find interesting examples of Markov processes under this definition; it is necessary to consider generalized random functions. In this paper we show that a natural framework for the Markov property of multiparameter processes is a class of generalized random differential forms (i.e., random currents). Our principal objective is to relate the Markovian nature of an isotropic gaussian current to its spectral properties.Work supported by the Army Research Office, Grant No. DAAG 29-85-K-0233Work done while at the University of California at Berkeley 相似文献
639.
Barnea E Andrea T Kapon M Berthet JC Ephritikhine M Eisen MS 《Journal of the American Chemical Society》2004,126(35):10860-10861
The coupling reaction of terminal alkynes and tert-butylisonitrile to yield substituted alpha,beta-acetylenic aldimines is catalyzed by the organoactinide neutral complexes Cp*2AnMe2 (Cp* = C5Me5, An = Th, U) and the cationic complex [(Et2N)3U][BPh4]. The reaction proceeds by a 1,1-insertion of the isonitrile into the metal-acetylide bond. Additional insertion products can be obtained by altering the catalyst and the reactant ratios. A plausible mechanism for the catalytic reaction is presented, in addition to the crystal structure of Cp*2UMe2 相似文献
640.
D'Alessandro DM Keene FR Bergman SD Kol M 《Dalton transactions (Cambridge, England : 2003)》2005,(2):332-337
The dinuclear species [{Ru(bpy)2}2(micro-dbneil)]4+(bpy = 2,2'-bipyridine; dbneil = dibenzoeilatin) was separated into its three stereoisomeric forms by cation-exchange chromatographic techniques. The NMR characteristics of the two diastereoisomers (meso and rac) are very similar, consistent with the decreased anisotropic interactions between the terminal bpy ligands located on different ruthenium centres because of their large spatial separation. Spectroelectrochemical measurements of the IVCT transitions in the mixed valence (5+) species show the system to be in the class II-III regime with substantial electronic communication between the metal centres. There is no significant difference in IVCT behaviour between the two diastereoisomers. 相似文献