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排序方式: 共有358条查询结果,搜索用时 31 毫秒
261.
Existing techniques for solving nonconvex programming problems often rely on the availability of lower and upper bounds on the problem variables. This paper develops a method for obtaining these bounds when not all of them are availablea priori. The method is a generalization of the method of Fourier which finds bounds on variables satisfying linear inequality constraints. First, nonlinear inequality constraints are converted to equivalent sets of separable constraints. Generalized variable elimination techniques are used to reduce these to constraints in one variable. Bounds on that variable are obtained and an inductive process yields bounds on the others.Research Sponsored by the Office of Naval Research Grant N00014-89-J-1537. 相似文献
262.
M. K. El-Mansy M. M. El-Zaidia E. Abo El-Hassan A. A. Ammar 《Il Nuovo Cimento D》1995,17(10):1121-1130
Summary Thick layers of GeTeSe chalcogenide glass have been prepared and subjected to conduction measurements under the effect of
both temperature and pressure. The results of theI–V characteristics exhibit transition from high-resistance state to differential negative resistance state through a turnover
point. The application of uniaxial pressure shows the similar effect of temperature on that behaviour. Both current and voltage
at the turnover point depend on pressure and ambient temperature. The rise of temperature in the conduction path due to joule
heating and application of uniaxial pressure as well as the reduction in the energy gap width (β=2.87·10−12eV/N m−2) are estimated and discussed at the turnover point. This behaviour is explained according to the orientation of dipoles randomly
dispersed in viscous amorphous matrix. 相似文献
263.
The aim of this Letter is to characterize the representations of Euclidean Ka-Moody with highest weight, spanned by the principal subalgebra action on a highest-weight vector.We conjecture that, modulo the Dynkin diagram automorphisms, only the basic representations have this property. This is proved for A
infn
sup(1)
, D
inf4
sup(1)
, and A
inf2
sup(2)
. 相似文献
264.
Bortoletto D Goldberg M Horwitz N Mestayer MD Moneti GC Sharma V Shipsey IP Skwarnicki T Csorna SE Letson T Brock IC Ferguson T Alexander J Artuso M Bebek C Berkelman K Cassel DG Cheu E Coffman DM Crawford G DeWire JW Drell PS Ehrlich R Galik RS Gittelman B Gray SW Halling AM Hartill DL Heltsley BK Kandaswamy J Kowalewski R Kreinick DL Kubota Y Lewis JD Mistry NB Mueller J Namjoshi R Nandi S Nordberg E O'Grady C Peterson D Pisharody M Riley D Sapper M Silverman A Stone S Worden H Worris M 《Physical review letters》1989,63(16):1667-1670
265.
Let G be a transitive permutation group on a finite set of size at least 2. By a well known theorem of Fein, Kantor and Schacher, G contains a derangement of prime power order. In this paper, we study the finite primitive permutation groups with the extremal property that the order of every derangement is an r-power, for some fixed prime r. First we show that these groups are either almost simple or affine, and we determine all the almost simple groups with this property. We also prove that an affine group G has this property if and only if every two-point stabilizer is an r-group. Here the structure of G has been extensively studied in work of Guralnick and Wiegand on the multiplicative structure of Galois field extensions, and in later work of Fleischmann, Lempken and Tiep on \({r'}\)-semiregular pairs. 相似文献
266.
New strategy for the biosorption of atrazine after magnetic solid‐phase extraction from water followed by high‐performance liquid chromatography analysis 下载免费PDF全文
We describe a rapid and simple microextraction of atrazine from water samples. This method is based on the use of magnetic nanoparticles as sorbents and bioaggregates that are applied to the extraction and preconcentration of atrazine. The resulting magnetic nanoparticles possess a fast adsorption kinetics and high adsorption capacity. Bioaggregates made up of rhaminolipid biosurfactant were assessed as a new strategy for the sample treatment. The extractant was obtained from magnetic nanoparticles using the magnetic solid‐phase extraction method. Then the target analyte was rapidly transferred from the sorbent surface to bioaggregates, which have a low toxicity and are green and ecofriendly. Finally, the extract is centrifuged and transferred to micro‐syringe for analysis by high‐performance liquid chromatography. Experimental parameters affecting the extraction efficiency were studied and optimized. Under optimum conditions the enrichment factor was 268. The linear dynamic range and limit of detection were 0.1–50 and 0.033 μg/L, respectively. The relative standard deviation for six replicate measurements was 5.3%. The results demonstrate good applicability of biosorption‐assisted magnetic solid‐phase extraction method for the determination of atrazine from water samples. 相似文献
267.
Mehrzia Krimi Ammar Fatma Ben Amor Tahar Jouini Ahmed Driss 《Journal of chemical crystallography》2002,32(3-4):87-89
The synthesis and crystal structure of a new dinuclear complex Cu2(C2H4N4)2 (CH3N3)4 are reported. It crystallizes in the monoclinic system of space group P21/c, with a = 8,459(1) Å, b = 15,481(3) Å, c = 8,714(2) Å, = 110,60(1)°, and Z = 2. The centrosymmetric molecular structure of Cu2(C2H4N4)2(CH3N3)4 comprises a tetrakis(guanidino)-bridged dinuclear copper(II) core with axially located cnge moities. 相似文献
268.
Alexander J Bebek C Berkelman K Besson D Browder TE Cassel DG Cheu E Coffman DM Drell PS Ehrlich R Galik RS Garcia-Sciveres M Geiser B Gittelman B Gray SW Hartill DL Heltsley BK Honscheid K Kandaswamy J Katayama N Kim PC Kreinick DL Lewis JD Ludwig GS Masui J Mevissen J Mistry NB Nandi S Ng CR Nordberg E O'Grady C Patterson JR Peterson D Pisharody M Riley D Sapper M Selen M Worden H Worris M Avery P Freyberger A Rodriguez J Yelton J Henderson S Kinoshita K Pipkin F Saulnier M Wilson R 《Physical review letters》1992,68(9):1275-1278
269.
Avery P Freyberger A Rodriguez J Stephens R Yelton J Cinabro D Henderson S Kinoshita K Liu T Saulnier M Wilson R Yamamoto H Ong B Selen M Sadoff AJ Ammar R Ball S Baringer P Coppage D Copty N Davis R Hancock N Kelly M Kwak N Lam H Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Romero V Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F 《Physical review letters》1993,71(15):2391-2395
270.
Kinoshita K Pipkin FM Procario M Wilson R Wolinski J Xiao D Zhu Y Ammar R Baringer P Coppage D Davis R Haas P Kelly M Kwak N Lam H Ro S Kubota Y Nelson JK Perticone D Poling R Schrenk S Crawford G Fulton R Jensen T Johnson DR Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Bortoletto D Brown D Dominick J McIlwain RL Miller DH Modesitt M Ng CR Schaffner SF Shibata EI Shipsey IP Battle M Kroha H Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Romero V Sun CR Wang P Zoeller MM Goldberg M 《Physical review D: Particles and fields》1991,43(9):2836-2842