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  • Artikel  (66)
  • Polymer and Materials Science  (65)
  • Ellipsoid method  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Mathematical methods of operations research 46 (1997), S. 131-142 
    ISSN: 1432-5217
    Schlagwort(e): Ellipsoid method ; linear programming ; simplex ; volume
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Notizen: Abstract Yamnitsky and Levin proposed a variant of Khachiyan's ellopsoid method for testing feasibility of systems of linear inequalities that also runs in polynomial time but uses simplices instead of ellipsoids. Starting with then-simplexS and the half-space {x¦a Tx ≤ β}, the algorithm finds a simplexS YL of small volume that enclosesS ∩ {x¦a Tx ≤ β}. We interpretS YL as a simplex obtainable by point-sliding and show that the smallest such simplex can be determined by minimizing a simple strictly convex function. We furthermore discuss some numerical results. The results suggest that the number of iterations used by our method may be considerably less than that of the standard ellipsoid method.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 1 (1992), S. 299-308 
    ISSN: 1057-9257
    Schlagwort(e): LPCVD ; Tantalum pentoxide ; High dielectric constant ; ULSI devices ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: A laminar flow low-pressure chemical vapour deposition (LPCVD) system (LAM IntegrityTM) has been used to deposit tantalum pentoxide (Ta2O5) from Ta(OEt)5 films in the presence of oxygen (O2) at 470 °C at a typical deposition rate of 4 nm min-1. Uniformities of 〈1.5% (SD 1σ) over a 150 mm silicon substrate were obtained. The layers were annealed under different conditions. It was discovered that the films did not change their stoichiometry as determined by Rutherford backscattering (RBS). The as-deposited films were amorphous but became crystalline (β-Ta2O5) at temperatures 〉 700 °C. The transmission electron microscopy (TEM) results on crystallisation behaviour were supported by X-ray diffraction data. The electrical properties of the Ta2O5 films have been characterised using MIS (metal/insulator/silicon) capacitor structures. Leakage values of 〈10-6 A cm-2 at 6 MV cm-1 equivalent applied electric field and breakdown strengths of 〉7 MV cm-1 at 1.6 μA were obtained for annealed layers. Compound dielectric constants (native silicon oxide thickness of about 2.5 nm plus Ta2O5 of various thicknesses) between 14 and 〉30 have been measured. The electrical properties reveal the potential use of Ta2O5 as a storage capacitor dielectric in 64 and 256 Mbit DRAM (dynamic random access memory) devices.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 5 (1995), S. 163-175 
    ISSN: 1057-9257
    Schlagwort(e): ULSI ; high dielectric constant ; metal oxides ; deposition ; annealing ; characterisation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Flims of metal oxides, such as Ta2O5, Nb2O5, Al2O3, HfO2, ZrO2 and TiO2 have been fabricated by use of different precursor materials, deposition techniques and annealing techniques. Several analytical methods were applied to study the layers. New data of fundamental properties of these metal oxides are reported and related to practical features that are of importance in device design and manufacturing of advanced, highly integrated devices. This overview may facilitate the choice of an optimal combination of precursor material, deposition technique and corresponding annealing procedure for a specific application of these metal oxide films in microelectronics.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 3123-3131 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The thermal stabilities of polybutadienyllithium, polyisoprenyllithium, and polystyryllithium solutions have been determined in hydrocarbon solvents. Kinetic analysis indicated that a complex mechanism was involved in the thermolysis of polybutadienyllithium. The thermal stability was observed to increase with increasing lithium concentration, suggesting the presence of competitive reactions in addition to the expected elimination of lithium hydride. The thermal stability of the three systems studied was consistent with their reported degrees of association: dimeric polystyryllithium was less stable than tetrameric polyisoprenyllithium or hexameric polybutadienyllithium.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 3133-3144 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In addition to the expected elimination of lithium hydride, metalation and addition reactions have been observed as competitive, thermolytic reactions of polybutadienyllithium. The importance of these reactions at temperatures frequently utilized for the polymerization of butadiene was illustrated and the effect of these reactions on the macrostructure of polybutadiene determined.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 156 (1972), S. 3-5 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Linear oligourethanes with phenylurethane endgroups and cyclic oligourethanes were prepared from diethylene glycol and hexamethylene diisocyanate. The largest ring synthesized contains seven units of each, i.e., 119 ring atoms, with a molecular weight of 1920.An effective separation of the oligomers was achieved by adsorption column chromatography. An eluting solvent with solvent gradient was applied successfully. Melting points, transitions, long periods, and X-ray diffraction of the oligomers prepared are discussed with regard to their structure.
    Notizen: Es wurden lineare Oligourethane mit Phenylendgruppen und cyclische Oligourethane aus Diäthylenglykol und Hexamethylendiisocyanat dargestellt. Der größte bisher isolierte Ring enthält je sieben Grundbausteine und besitzt 119 Ringglieder bei einem Molekulargewicht von 1920.Eine gute Trennung der Oligomeren wurde durch Adsorptionssäulenchromatographie erzielt. Hierbei wurde ein Elutionsmittel mit Lösungsmittelgradient verwendet. Schmelzpunkte, Umwandlungserscheinungen, Langperioden und Weitwinkeldiagramme der Oligomeren werden im Hinblick auf ihre Struktur diskutiert.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 1 (1967), S. 150-173 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Gelchromatographie kann als eine netzwerk-limitierte Verteilung aufgefaßt werden. Dies führt zu dem Schluß, daß keine normierende Eichbezeichnung, zwischen Molekulargewicht und Elutionsvolumen existiert, die ausschließlich, der gelösten Substanz abhängige Parameter enthält.Die Darstellung von Gelen mit unterschiedlicher chemischer Struktur wird be schrieben, und die Möglichkeiten, die Porengröße zu variieren, werden diskutiert. Die Untersuchung des Einflusses der physikalischen und chemischen Struktur auf die Trennung und die Trennleistung zeigte, daß das Elutionsvolumen durch die chemische Natur des Gels beeinflußt wird; die Trennleistung wird hingegen im wesentlichen durch die physikalische Struktur bestimmt.
    Notizen: Gel chromatography can be considered as a network-limited partition. This leads to the conclusion that it is impossible to find a generalizing relationship between the molecular weight and the elution volume using parameters depending only on the solute.The preparation of gels with different chemical structure is discussed and possible methods for the alteration of pore size are described. Investigations of the influence of the physical and chemical structure on separation and separation efficiency have shown that the elution volume depends to some extent on the chemical nature, but the separation efficiency is mainly a function of the physical structure.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 2539-2542 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: N-Ethylaziridine (1) was polymerized in water with HCl as initiator and copolymerized with N-(2-hydroxyethyl)aziridine (2). Rapid propagation and termination reactions were observed. The maximum yield increases with the initiator concentration, whereas the molecular weight decreases. This is due to the difference in basicity between the tertiary N-atoms of the two monomers and the tertiary and the terminal secondary N-atoms of the polymers, which causes tranfer and termination reactions. Macrocycles with a side chain on a quaternary N-atom are formed. During the copolymerization, the more basic 1 is preferentially incorporated into the copolymer chain. The copolymerization parameters can be estimated roughly on the basis of basicity considerations: r1 〉 1; r2 〈 1. The ratio of the rate constants (propagation to termination) is lower for 1 than for 2. This is due to the fact that the basicity difference between the monomer and the tertiary N-atoms of the polymer is higher for 1 than for 2. By reaction of thionyl chloride with the copolymers the desired hydrochlorides of the N-(2-chloroethyl) derivatives are obtained. The neutralisation with alkali did not result the free bases, since the products formed are rather due to side reactions.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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