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  • Engineering  (106)
  • Inorganic Chemistry
  • 1995-1999  (166)
  • 1950-1954
  • 1930-1934
  • 1920-1924
  • 1997  (75)
  • 1996  (91)
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  • 1995-1999  (166)
  • 1950-1954
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  • 1
    Electronic Resource
    Electronic Resource
    NiH3IO6 · 6H2O  -  Kristallstruktur und Schwingungsspektren (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 845-852 
    Details
    ISSN: 0044-2313
    Keywords: Nickel orthoperiodate ; i.r., Raman spectra ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: NiH3IO6 · 6 H2O  -  Crystal Structures and Vibrational SpectraThe crystal structure of NiH3IO6 · 6 H2O has been determined by X-ray single-crystal diffraction (Pc, Z = 2, a = 516.74(9), b = 981.5(2), c = 1052.5(2) pm, β = 116.496(8)°) on the basis of 4169 unique reflections (R = 1.96%). The structure is built up of distorted Ni(H2O)62+ and H3IO62- octahedra linked by hydrogen bonding. IR and Raman spectra of both the title compound and isostructural MgH3IO6 · 6 H2O as well as of deuterated specimens are given. There are up to 14 different OH(OD) modes in the spectra of isotopically dilute samples due to the 15 different hydrogen positions of the structure. The internal modes of the meridional H3IO62- ions (pseudo C2v symmetry) are discussed with respect to that double T-shaped entity, which gives rise to only two instead of 3I—O, I—O(H), and OH stretches in the IR and Raman spectra, i.e. the same as for facial (C3v) structured ions.
    Notes: Die Kristallstruktur (Pc, Z = 2) von NiH3IO6 · 6 H2O wurde mittels Röntgen-Einkristallmessungen auf der Basis von 4169 symmetrieunabhängigen Reflexen bestimmt (R = 1,96%). IR- und Raman-Spektren von NiH3IO6 · 6 H2O und der isotypen Verbindung MgH3IO6 · 6 H2O sowie von deuterierten Präparaten werden mitgeteilt. Die Spektren isotypenverdünnter Proben zeigen bis zu 14 OH(OD)-Streckschwingungen entsprechend den 15 verschiedenen Wasserstoff-Positionen der Struktur. Die meridionalen H3IO62--Ionen (Pseudosymmetrie C2v) besitzen wegen der T-förmigen Anordnung der je 3 IO-und IOH-Gruppen nur je 2 IO-, IO(H)- und OH-Streckschwingungen in den IR- und Raman-Spektren und können daher schwingungsspektroskopisch nicht von H3IO62--Ionen mit facialer Struktur (C3v) unterschieden werden.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19966220516
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  • 2
    Electronic Resource
    Electronic Resource
    ON THE SIGN OF THE DETERMINANT OF THE STRUCTURAL STIFFNESS MATRIX FOR DETERMINATION OF LOADING INCREMENT IN ARC-LENGTH ALGORITHMS (1997)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 13 (1997), S. 47-49 
    Details
    ISSN: 1069-8299
    Keywords: nonlinear structural analysis ; arc-length algorithm ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper, we have proved in theory that the sign of the current stiffness matrix provides a correct indicator for determining the sign of the loading parameter in the arc-length algorithm before the first bifurcation point is encountered, but may not be the case thereafter. © 1997 John Wiley & Sons, Ltd.
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  • 3
    Electronic Resource
    Electronic Resource
    AN ADAPTIVE AGGLOMERATION METHOD FOR ADDITIVE CORRECTION MULTIGRID (1997)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 40 (1997), S. 887-903 
    Details
    ISSN: 0029-5981
    Keywords: multigrid ; adaptive agglomeration ; additive correction ; anisotropic grids ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In the computational simulation of fluid flow and scalar transport, multigrid iterative solution techniques often fail or stall when the discrete linearized equations have strongly anisotropic coefficients. In the present work, an adaptive agglomeration algorithm for forming coarse grids is presented that allows multigrid techniques to work efficiently for equation sets with anisotropic coefficients. The adaptive agglomeration is defined by two rules and several guidelines that follow from a physical interpretation of the performance of iterative solvers like Gauss-Seidel. The effectiveness of the adaptive agglomeration algorithm is demonstrated for a wide range of test cases. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 10 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    CONSISTENT LINEARIZATION FOR THE EXACT STRESS UPDATE OF PRANDTL-REUSS NON-HARDENING ELASTOPLASTIC MODELS (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 1219-1235 
    Details
    ISSN: 0029-5981
    Keywords: plasticity ; numerical integration algorithms ; consistent linearization ; finite elements ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper presents a consistent algorithm, which combines the advantages of the exact time integration of Prandtl-Reuss elastoplastic models and the quadratic asymptotic convergence of Newton-Raphson iteration strategies. The consistent modulus is evaluated by a full linearization of the exact stress update procedure. Numerical tests for a thin wall tube subjected to combined loads of tension and torsion are performed to illustrate the accuracy and efficiency of the consistently linearized exact stress update algorithm described in the paper. For comparison purpose numerical results of the radial return method are also given.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    COMPARATIVE EVALUATION OF DIFFERENT OPTIMIZATION ALGORITHMS FOR STRUCTURAL DESIGN APPLICATIONS (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 1761-1774 
    Details
    ISSN: 0029-5981
    Keywords: optimization ; algorithms ; structural ; design ; comparative ; evaluation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Non-linear programming algorithms play an important role in structural design optimization. Fortunately, several algorithms with computer codes are available. At NASA Lewis Research Centre, a project was initiated to assess the performance of eight different optimizers through the development of a computer code CometBoards. This paper summarizes the conclusions of that research. CometBoards was employed to solve sets of small, medium and large structural problems, using the eight different optimizers on a Cray-YMP8E/8128 computer. The reliability and efficiency of the optimizers were determined from the performance of these problems. For small problems, the performance of most of the optimizers could be considered adequate. For large problems, however, three optimizers (two sequential quadratic programming routines, DNCONG of IMSL and SQP of IDESIGN, along with Sequential Unconstrained Minimizations Technique SUMT) outperformed others. At optimum, most optimizers captured an identical number of active displacement and frequency constraints but the number of active stress constraints differed among the optimizers. This discrepancy can be attributed to singularity conditions in the optimization and the alleviation of this discrepancy can improve the efficiency of optimizers.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Synthese und Struktur von Hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octan - Eine neue Käfigverbindung mit dem Sn(P2)3Sn-Gerüst (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 1793-1798 
    Details
    ISSN: 0044-2313
    Keywords: Sn(P2)3Sn cage system ; NMR data, crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of Hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octane - a New Cage Compound with the Sn(P2)3Sn SkeletonThe reaction of the diphosphide K2[(tBuP)2] 1 with SnCl4 leads by a redox process mainly to (tBuP)3,4 and other sideproducts. However, at the same time a threefold [2 + 1]-cyclocondensation reaction takes place yielding the new cage compound hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octane, ClSn(tBuP—PtBu)3SnCl 2. 2 could be obtained in a pure form and characterized 31P and 119Sn NMR spectroscopically; 2 was also characterized by a single crystal structure analysis.
    Notes: Bei der Reaktion zwischen dem Diphosphid K2[(tBuP)2] 1 und SnCl4 finden überwiegend Redoxreaktionen statt, die zu (tBuP)3,4 und weiteren Nebenprodukten führen. Gleichzeitig findet aber auch eine dreifache [2 + 1]-Cyclokondensation statt, bei der die neuartige Käfigverbindung Hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphospha-bicyclo[2.2.2]octan, ClSn(tBuP—PtBu)3SnCl 2 gebildet wird. 2 konnte in reiner Form isoliert und 31P- und 119Sn-NMR-spektroskopisch sowie durch eine Einkristallstrukturanalyse charakterisiert werden.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19966221026
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  • 7
    Electronic Resource
    Electronic Resource
    A numerical representation of fracturing granular materials (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 21 (1997), S. 825-843 
    Details
    ISSN: 0363-9061
    Keywords: fracture modelling ; granular materials ; numerical modelling ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: This paper describes the computer algorithms used in a numerical simulation of the compression of an aggregate of crushable grains. It has been used in a model for the evolution of a granular medium under one-dimensional compression, in which the probability of fracture for individual particles is a function of applied stress, particle-size and co-ordination number. The information relating to the particles is represented in a compact way on the computer which allows the number of particles produced to become sufficiently large for satisfactory comparisons to be made with experimental data and which allows information, such as the positions and sizes of the particles, to be easily extracted. An algorithm based on the representation is used to locate neighbouring particles in a way which does not deteriorate unacceptably in terms of speed as the number of particles increases. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 13 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Synthese der Stannatetraphospholane (tBuP)4SnR2 (R = tBu, nBu, C6H5) und (tBuP)4Sn(Cl)nBu Molekül- und Kristallstruktur von (tBuP)4Sn(tBu)2Professor Ekkehard Fluck zum 65. Geburtstag gewidmet (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 1167-1172 
    Details
    ISSN: 0044-2313
    Keywords: Phosphorus tin heterocycles ; syntheses ; crystal structure ; NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of the Stannatetraphospholanes (tBuP)4SnR2 (R = tBu, nBu, C6H5) and (tBuP)4Sn(Cl)nBu Molecular and Crystal Structure of (tBuP)4Sn(tBu)2The reaction of the diphosphide K2[tBuP-(tBuP)2-PtBu] 4 with the halogenostannanes (tBu)2SnCl2, (nBu)2SnCl2, (C6H5)2SnCl2 or nBuSnCl3 in a molar ratio of 1 : 1 leads via a [4 + 1]-cyclocondensation reaction to the stannatetraphospholanes (tBuP)4SnR2 3 b-3 d and (tBuP)4Sn(Cl)nBu 3 e, respectively, with the binary 5-membered P4Sn ring system. 3 b was characterized by a single crystal structure analysis; the 5-membered ring exists in a planar conformation. The compounds 3 b-3 e were identified by NMR and also by mass spectroscopy; the 31P{1H}-NMR spectra of 3 b-3 d showed an AA′MM′ (AA′MM′X), 3 e on the other hand an ABCD (ABCDX) spin system.
    Notes: Bei der Reaktion zwischen dem Diphosphid K2[tBuP-(tBuP)2-PtBu] 4 und den Halogenstannanen (tBu)2SnCl2, (nBu)2SnCl2, (C6H5)2SnCl2 bzw. nBuSnCl3 im Molverhältnis 1 : 1 findet eine [4 + 1]-Cyclokondensationsreaktion statt, bei der die Stannatetraphospholane (tBuP)4SnR2 3b-3d bzw. (tBuP)4Sn(Cl)nBu 3 e mit dem binären Fünfringgerüst P4Sn gebildet werden. Von 3 b wurde eine Einkristallstrukturanalyse durchgeführt; das Fünfringgerüst zeigt eine planare Konformation. Die Verbindungen 3 b-3 e wurden Massen- und NMR-spektroskopisch charakterisiert; 3 b-3 d liefern im 31P{1H}-NMR-Spektrum ein AA′MM′-(AA′MM′X)-, 3 e dagegen ein ABCD- (ABCDX)-Spinsystem.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19966220710
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  • 9
    Electronic Resource
    Electronic Resource
    Kristallstruktur von CF3TeTeCF3 - Synthese, Charakterisierung und Eigenschaften von CF3TeIProfessor Herbert Jacobs zum 60. Geburtstag gewidmet (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 617-621 
    Details
    ISSN: 0044-2313
    Keywords: Trifluoromethyl tellurium compounds ; crystal structure ; NMR spectra ; metathesis reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of CF3TeTeCF3. Synthesis, Characterization, and Properties of CF3TeITe2(CF3)2 crystallizes in the monoclinic space group P21/a with four formular units in the unit cell. The lattice constants are a = 10.13(1) Å, b = 11.489(7) Å, c = 6.822(8) Å and β = 101.20(8)°. CF3TeI is prepared by a quantitative reaction of Te2(CF3)2 with equimolar amounts of iodine. This compound is very instable, no isolation is possible. NMR spectra have been registrated. From metathesis reactions CF3TeX (X = C≡CC6H5, t-C4H9, SCN, SC6F5) are prepared.
    Notes: Te2(CF3)2 kristallisiert in der monoklinen Raumgruppe P21/a mit vier Formeleinheiten in der Elementarzelle. Die Gitterkonstanten betragen a = 10,13(1) Å, b = 11,489(7) Å, c = 6,822(8) Å und β = 101,20(8)°. Bei der Umsetzung von Te2(CF3)2 mit der äquimolaren Menge Iod entsteht CF3TeI in quantitativer Ausbeute, eine Isolierung gelingt nicht. Die NMR-Spektren zeigen eine starke Lösungsmittelabhängigkeit. Durch Metathesereaktionen werden die Verbindungen CF3TeX (X = C≡CC6H5, t-C4H9, SCN, SC6F5) synthetisiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19966220407
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  • 10
    Electronic Resource
    Electronic Resource
    The Direct Synthesis of Arylxenon Trifluoromethanesulfonates via electrophilic substitutionProfessor Rudolf Hoppe zum 75. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1821-1834 
    Details
    ISSN: 0044-2313
    Keywords: Arylxenon trifluoromethanesulfonates ; electrophilic aromatic substitution ; xenontrifluoroacetate trifluoromethanesulfonate ; NMR spectra ; X-ray crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die direkte Synthese von Arylxenontrifluormethansulfonaten durch elektrophile SubstitutionBei der Reaktion von Xenonbis(trifluoracetat) mit Trifluormethansulfonsäure wird die neue, hochreaktive, unsymmetrische Xenon-Sauerstoff-Verbindung CF3COOXeOSO2CF3 erzeugt. Benzolderivate mit elektronenziehenden Substituenten wie F, CF3, Cl und NO2 werden von diesem Intermediat unter Bildung von Arylxenontrifluormethansulfonaten elektrophil angegriffen. Über diese Eintopfsynthese wurden Trifluormethansulfonate mit den Kationen [Xe(2,4,6-F3C6H2)]+, [Xe(2-F-5-NO2C6H3)]+, [Xe(2-F-5-CF3C6H3)]+ und [Xe(3,5-(CF3)2C6H3)]+ synthetisiert. Alle Verbindungen wurden durch ihre NMR-, Massen- und Schwingungsspektren charakterisiert.Zusätzlich wurden mehrere neue Arylxenontrifluormethansulfonate als Produkte der Umsetzungen von 1,3-F2C6H4 und weiteren desaktivierten Benzolen mit Xenon(trifluoracetat)trifluormethansulfonat anhand der 129Xe-NMR-Spektren identifiziert.Fluorsubstituenten in ortho-Position zu Xenon erhöhen signifikant die thermische Stabilität der Arylxenontrifluormethansulfonate.Die Molekülstruktur von [Xe(2,6-F2C6H3)][OSO2CF3] wurde durch eine Einkristallröntgenstrukturanalyse bestimmt. Die Arylxenoneinheit koordiniert schwach mit einem Sauerstoffatom des CF3SO3-Anions. Die Verbindung kristallisiert in der triklinen Raumgruppe mit a = 880.9(3) pm, b = 1093.9(5) pm, c = 1209.8(5) pm, α = 89.04(4)°, β = 74.23(3)°, γ = 86.03(3)°, Z = 4.
    Notes: The reaction of xenonbis(trifluoroacetate) and trifluoromethanesulfonic acid (triflic acid) gave the new, highly reactive unsymmetrical xenon-oxo species CF3COOXeOSO2CF3. Benzene derivates, containing electron withdrawing substituents such as -F, -CF3, -Cl or -NO2 were electrophilic attacked by this intermediate to yield arylxenon trifluoromethanesulfonates. Via this one-pot synthesis trifluoromethanesulfonates with the cations [Xe(2,4,6-F3C6H2)]+, [Xe(2-F-5-NO2C6H3)]+, [Xe(2-F-5-CF3C6H3)]+ and [Xe(3,5-(CF3)2C6H3)]+ were prepared. All compounds were characterized by their NMR, mass, and vibrational spectra.Additionally, several new arylxenon trifluoromethanesulfonates were detected by 129Xe-NMR spectroscopy as products of the reaction of 1,3-F2C6H4 and further deactivated benzenes with xenontrifluoroacetate trifluoromethane sulfonate.Fluoro substituents in ortho position to xenon significantly increase the thermal stability of the arylxenon trifluoromethanesulfonates obtained.The molecular structure of [Xe(2,6-F2C6H3)][OSO2CF3] was determined by single crystal diffraction methods. The arylxenon unit is weakly coordinated by one oxygen atom of the CF3SO3 anion. The salt crystallizes in the triclinic space group P1, a = 880.9(3) pm, b = 1093.9(5) pm, c = 1209.8(5) pm, α = 89.04(4)°, β = 74.23(3)°, γ = 86.03(3)°, Z = 4.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231127
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