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  • Electronic Resource  (1,093)
  • 1985-1989  (1,093)
  • 1985  (1,093)
  • Organic Chemistry  (671)
  • Engineering General  (422)
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  • Electronic Resource  (1,093)
Years
  • 1985-1989  (1,093)
Year
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 963-967 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The catalytic activity of sodium 1-dodecanesulfonate, sodium dodecyl sulfate, disodium 2-dodecyl-1, 3-propanediyl disulfate (1) and trisodium 2, 2-bis(sulfonatemethyl)tetradecylsulfate (2) was tested in the two-phase oxidation of p-xylene with cerium ammonium nitrate (CAN). Also various toluene derivatives were oxidized with CAN in the presence of sodium dodecyl sulfate. The observed reaction enhancements are discussed in terms of the micelle-substrate interaction. The catalytic oxidation of some toluene derivatives (3) with a subsequent thermal rearrangement of the oxidation product offers a simple synthetic route to benzaldehydes 4.
    Additional Material: 3 Tab.
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  • 102
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 968-982 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Use of Glyoxal Bis (t-Butyl Nitron) as a Spin TrapNitroxides derived from glyoxal bis(t-butyl nitrone), GBBN, have been studied by e.s.r. spectroscopy. Well resolved e.s.r. spectra exhibiting extra hyperfine splitting by magnetic active nuclei in γ-position have been recorded for the spin adducts of alkyl, as well as .N3 and .CH2Cl radicals. Enhanced stability was found for the spin adducts of halogen atoms. However, a wider application of this spin trap is limited by the strong superposition of the e.s.r. signals of different radical spin adducts which is directly related to almost identical conformations of these nitroxides.
    Additional Material: 8 Ill.
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  • 103
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 998-1006 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ortho-Specific Bromination of PhenolsPhenol as well as 3-substituted phenols are brominated exclusively in the orthopositions by N.N-dibromomethylamine, yielding 2.6-dibrominated phenols in excellent yields. Phenols bearing an ortho-substituent need N-bromomethylamine as the brominating agent to take up one bromine atom into the free ortho-position. para-Bromination is not observed in either case. 1-Naphthol gives 2-bromo-1-naphthol, 8-hydroxyquinoline gives 7-bromo-8-hydroxyquinoline with 80% and 98% yield respectively. ortho-Specific chlorination of phenols was carried out in some cases using N-chloro-alkylamines.
    Additional Material: 2 Tab.
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  • 104
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 1007-1010 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
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  • 105
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Pyrolysis of Unsubstituted Cyclanes - Selectivity of the Formation of Reaction Products, Kinetic Parameters, Mechanistic InterpretationsThe thermal decompostion of cyclopentane (1), cyclohexane (2), cycloheptane (3), cyclooctane (4), cyclodecane (5), and cyclododecane (6) was studied in a laboratoryscale metallic tubular reactor at 650 to 850°C in the presence of steam. The kinetic parameters for the overall reactions were determined and the gaseous as well as the liquid reaction products were analyzed and identified by gas chromatography or by the coupling of gas chromatography and mass spectrometry, respectively. It could be shown that from all cyclanes the isomeric α-olefines are formed, if the conversion of the starting cyclanes is small. This supports the view that the cyclane → α-olefin isomerization is an important initial reaction in pyrolysis of 1 up to 6. The results also demonstrate that the main pathway of degradation is a radical chain mechanism via cyclanyl radicals with β(C—C) bond scission and 1.4 or 1.5-H-isomerization of alkenyl radicals as the most important reaction steps.
    Additional Material: 3 Ill.
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  • 106
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 35-44 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Synthesis of 4,5-Dihydroxy-pyrazoles1-Aryl-pyrazolin-5-ones 1 are converted by Knoevenagel condensation with acetone or by reaction with 2,2-dimethyl-1,3-dioxolane 6 to 1-aryl-4-isopropyliden-pyrazolin-5-ones 2. The compounds 2 are epoxidized by hydrogen peroxide forming the spiro-epoxides 3, which can be cleaved to 4,5-dihydroxy-pyrazoles 4 under acidic conditions. 4-Acetoxy-5-hydroxy-pyrazoles 13 are formed directly, when 3 are cleaved in presence of acetic anhydride. The 3,3′,3′-trimethyl-1-(4-nitro-phenyl)-pyrazolin-4-spiro-2′-oxiran-5-one 3b undergoes rearrangement to the 1,3-dioxolo[4,5-c]pyrazole 12.
    Additional Material: 3 Tab.
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  • 107
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 45-50 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical Carboxylation of Cinnamoyl-1,1-bis(alkylthio)ethylenesCinnamoyl-1,1-bis(alkylthio)ethylenes (1a-1h) are reduced electrochemically in the presence of carbondioxide in aprotic media. The attack of CO2 takes place either in 1- or 5-position of cinnamoyl-1, 1-bis(alkylthio)ethylenes (1a-1h) depending on the nature of the aryl substituents. If CO2 reacts in position 1 carbonic acids 3 are obtained, reaction of carbondioxide in 5- position leads to the acids 2. The effects of different aryl substituents on the halfwave potentials and the preparative electrolyses have been investigated.
    Additional Material: 1 Ill.
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  • 108
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nitrogen-15 and Carbon-13 Chemical Shifts and 13C-1H, 13C-15N and 15N-15N Coupling Constants of Parasubstituted Arene Diazonium SaltsNitrogen-15 and carbon-13 chemical shifts and 13C-1H,13C-15N and 15N-15N coupling constants of 15N-enriched p-substituted arene diazonium salts are reported and within the ΔE-approximation investigated. It is shown that changes of ΔE should be taken into account when considering variation of the nitrogen-15 chemical shifts. The influence of substituent effects was discussed within the DSP (dual substituent parameter)-approach.
    Additional Material: 7 Ill.
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  • 109
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 80-84 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical Reduction and Azo-coupling of Ring Chlorinated p-Dimethylaminobenzenediazonium Salts. Hammett-CorrelationsThe polarographic half-wave potentials of ring halogenated 4-dimethylaminobenzenediazonium salts (6a-6j) can be linearly correlated with the total σ-constants Σσkorr (E1/2 = (0.25 Σσkorr + 0.33) V; r = 0.995), if for the dimethylamino group of the 3- or 3,5-halogenated derivatives corrected σ′p-constants are used. The Σσkorr-values determined can be used to correlate the influence of substituents on the azo-coupling kinetics (lg k/k0 = 2.46 Σσkorr; r=0,988).
    Additional Material: 2 Ill.
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  • 110
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 111
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 177-182 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-(Arylmethyleneamino)phthalimides (2a-c) carrying an o-substituent in the aryl group were prepared by the reaction of N-aminophthalimide with o-substituted benzaldehydes. The reaction of these compounds with Grignard reagents proceeded either by normal addition to one of the carbonyl groups to give 3a-c or by addition and cleavage to give 4-arylphthalaz-1-ones 5a-c. The steric effect exhibited by either the Grignard reagent or the N-arylmethylene compound was studied. The reaction of N-furfurylideneaminophthalimide (2d) with Grignard reagents was also investigated. N-(Arylmethyleneamino)phthalimides reacted with primary amines to give N,N′-dialkylphthalamides (7a and b) while the reaction with secondary amines gave (8a and b).
    Additional Material: 3 Tab.
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  • 112
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    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 209-219 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on the Hydrolytic Stability of 4-Arylmethylidene-2-pyrazolin-5-onesThe 4-Arylmethylidene-2-pyrazoline-5-ones S are not stable under aqueous alkaline conditions. By the substitution of R3 with electron donor substituents S reacts preferably yielding aldehyde A and 2-pyrazoline-5-one P, while with electron acceptor substituents S forms 4,4′-aryl-methylidene-bis-2-pyrazoline-5-one B. The intermediate of hydrolysis is 4-(arylhydroxymethyl)-2-pyrazoline-5-one SOH.The second order rate constants of the reaction of S with hydroxidions and with 2-pyrazoline-5-ones P- are determined. The dependence of the hydrolytic decomposition of S on the pH vaue substituents and temperature is suitable for the intermediate formation of SOH.
    Additional Material: 4 Ill.
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  • 113
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    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 220-226 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash Spectroscopic Investigations on 1-Phenylazo-2-Naphthols1-(p-R-Phenylazo)-2-naphthols with R = NMe2, OH, OCH3, CH3, H, F, Br, COCH2, NO2, CN show reversible bleaching over the entire visible and near u.v. spectral region upon flash photolysis in ethanol and toluene. It is proposed to interpret this by photochemical formation of the corresponding cis-azo compound. The thermal relaxation is not an elementary reaction but it involves intermediate tautomerisation. A V-shaped Hammett correlation is found for the rate constants of the thermal relaxation.
    Additional Material: 6 Ill.
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  • 114
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    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 235-240 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Consecutive Products of Sulphonamides. VI. Synthesis and Cyclization of N-Allyl-N′-arylsulphonyl-thioureasN-Allyl-N′-arylsulphonyl-thioureas 3a-e are synthesized by addition reaction of substituted arensulphonamides 2a-e and allylisothiocyanate 1. The thioureas 3a-e react with hydrogen bromide in acetic acid or bromine in chloroform to 2-(arylsulphonylimino)-5-methyl-(or bromomethyl)thiazolidines 8a-j. The mechanism of reaction and the structures are discussed by means of i.r., m.s. and 1H-n.m.r. data.
    Additional Material: 2 Tab.
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  • 115
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemistry of Organic Cations. II. Investigations about the Cathodic Behaviour of the Acridizinium Ion and the Cathodically Catalyzed Cleavage of its PhotodimerThe cathodic reduction of the acridizinium ion Az⊕ and of its photodimer (Az⊕)2 in acetonitrile and in dimethylformamide leads via the radicals Az⋅ to the same red electrodimer Az-Az. In the case of (Az⊕)2 an electrochemically initiated cleavage to Az⊕ is involved. It was shown by cyclic voltammetry, coulometry and homogeneous electron transfer experiments using the anion radicals of some quinones and aromatic hydrocarbons as electron donors that this process occurs by a chain reaction with the dissociative one-electron transfer from Az⋅ to (Az⊕)2 as the elementary step. The mechanism of the anodic oxidation of Az-Az, which regenerates Az⊕, was investigated by electrogenerated chemiluminescence. The results are discussed in terms of the sensitized photochemical cleavage of (Az⊕)2.
    Additional Material: 4 Ill.
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  • 116
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 285-290 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantum Chemical Studies on Colour and Stereodynamics of Acyclic Azines. XV. On the Structural Aspect of the Photochromic EffectFor the longest-wavelength colour-determining electronic transition of selected arylsubstituted acyclic azines the curvature of λ=λ(θcc) has been adapted by means of polynomic and trigonometric functions. On this basis it is possible to discuss the structural aspect of the photochromic and aphotochromic behaviour being observed due to the (E, Z) isomerization.
    Additional Material: 1 Ill.
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  • 117
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    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 428-432 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iodation of N-Aryl-2,4-dimethyl-buta-1,3-dien-1,4-sultamesBy the iodation of N-aryl-2,4-dimethyl-buta-1,3-dien-1,4-sultames 1 with I2/HgO in EtOH/AcOH the 1,2-thiazine ring is substituted. The monosubstitution occurs on the 1-position (1a, d) and the disubstitution on the 1,3-position (3a). By iodine monochloride in CHCl3 the sultames 1a-d were substituted in the (C-2)-CH3 group (4a-d), in contrast also to the results of chlorination and bromination of 1. The structure of the products 2, 3, 4 was proved by 13C-n.m.r. spectroscopic data.
    Additional Material: 3 Tab.
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  • 118
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects in 13C-N.M.R. Spectra of Diastereomeric Chalcone Dihalogenides. VI. Assignment of Configuration on Chalcone Rhodanohydrins by Solvent Induced Shift of Signals in 13C-N.M.R. SpectraThe erythro configuration of chalcone rhodanohydrins 1 was determined by comparison of solvent dependent shifts of C-α and C-β signals of 1 and both the erythro and threo isomeres of chalcone chlorohydrins 2 as standard in 13C n.m.r. spectra.
    Additional Material: 1 Ill.
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  • 119
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    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 433-444 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C- and 1H-NMR-spectroscopical Investigations of 2,9-substituted FluorenesThe 13C- and 1H-chemical shifts for a series of 9-substituted fluorenes and 9-substituted 2-nitrofluorenes, where the substituents are various azarenium ions, have been determined, shift data for several other fluorenyl compounds are also presented. The exact assignments of the 13C-signals are possible by comparison of calculated shifts from 13C-data with experimental 1H-values. The substituent effects are discussed in terms of transmissions of electronic interactions. The substituent chemical shifts (SCS) for selective positions of the fluorene system give a linear correlation with the substituent constants σI, F, respectively. An increment model for the calculation of the empirical 13C-chemical shifts of N-(2-nitrofluorene-9-yl)azareniumions 3b-6b are presented.
    Additional Material: 2 Ill.
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  • 120
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    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 445-454 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Amination of Isoquinoline Bases3, 3-Pentamethylene oxaziridine 1 forms an N—N-bond with secondary isoquinoline bases 2a-f to give the cyclohexylidene hydrazines 3a-f. In some cases nitrogen elimination yielding indane derivatives 13b, 13e competes with hydrazone formation. The cyclic Schiff'base 14 and the β-carboline derivative 16 can also be aminated.
    Additional Material: 3 Tab.
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  • 121
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 455-462 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-(3-Aminothioacryloyl)-formamidines 3 react with primary amines to give either 4(1H)-pyrimidinthiones 6 or transaminated N-(3-aminothioacryloyl)-formamidines 5. Alkylation of the latter compounds gives rise to cyclised 6(1H)-pyrimidinimines 7. The 4(1H)-pyrimidinthiones 6 can be S-alkylated to 4-alkylmercaptopyrimidinium salts 8. Subsequent substitution of the alkylmercapto group of the 8 results in the formation of 4-aminopyrimidinium salts 9, which can also be obtained starting from the 3 by a reversed reaction sequence that is first by S-alkylation to 3-alkylmercapto-2-azapentamethinium salts 10 and subsequent reaction with primary amines.
    Additional Material: 3 Tab.
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  • 122
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N, N′-Bis(aminomethylidene)thioureas 1 react with electron acceptor substituted methyl halides 2 under the formation of 2-formamidinothiazoles 4. The reaction of N-(3-aminothioacryloyl)-formamidines 5 with substituted methyl halides 2 gives either 2-formamidinothiophenes 7 or 2-aminovinylthiazoles 8. The 8 can be hydrolysed to corresponding 2-hydroxyvinylthiazoles 9. 2-Aminovinylthiazoles 11 bearing primary amino groups are obtained by transamination of the N-(3-aminothioacryloyl)-formamidines 5 and subsequent reaction of the resulting 10 with substituted methyl halides 2.
    Additional Material: 2 Tab.
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  • 123
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 471-478 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 2,4-Bisalkyl(aryl)amino-6-cyanamino-s-triazinesReaction of 2,4-bisalkyl(aryl)amino-6-chloro-s-triazines with disodiumcyanamide to 2,4-bisalkyl(aryl)amino-6-cyanamino-s-triazines (3a-g) strongly depends on the solvent used. In dimethylformamide by-products predominate. The best results are found in dimethylsulphoxide.
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  • 124
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 479-486 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cleavage of Z-Group and Formation of Hydantoine during Saponification of Z-Peptide EstersIn the course of alkaline decomposition of the tetrapeptide ester Z-Arg(NO2)-Gly-Phe-Phe-OMe one gets a high output of a by-product. the latter was isolated and identified by 13C-n.m.r. spectroscopy to be the hydantoine derivative arising from a loss of Z-group and from a cyclisation. A possibility to suppress the undesired side-reaction by addition of benzylalcohol is proposed resulting from the discussion of a probable mechanism of reaction.
    Additional Material: 2 Ill.
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  • 125
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 555-566 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-N.M.R. Spectroscopic Investigations of the Azo-Hydrazon-Equilibrium in Substituted 1-Phenylazo-2-naphtholsIn substituted 1-phenylazo-2-naphthols an equilibrium between the azoic and the quinoid hydrazone form is observed. It is possible to obtain the equilibrium constants by means of 1H-n.m.r.-spectroscopy in CDCl3. Both chemical shifts δH-3 and δH-8 in the naphthalene ring system can be used to determine independently the equilibrium constants. 1-Phenylazo-2-naphthylamine and 1-(pyrid-2-ylazo)-2-naphthole were used as reference substances for the pure azoic and hydrazone form, respectively. An appropriate correction is introduced to compare the different influence of OH- und NH2-groups, respectively, on the protons H-3 and H-8.All equilibrium constants measured show a linear correlationship with respect to Hammett-σ-constants of the substituents attached to the phenyl ring. The standard reaction entropy for the conversion of the azoic form into the hydrazone form is always negative and of nearly identical magnitude. Obviously, no substituent effect to this value exists. One possibility to interprete these results is to assume that the quinoid hydrazone form shows a higher tendency to aggregation.
    Additional Material: 2 Ill.
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  • 126
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 567-579 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iminoformylation Reaction of Substituted Crotonnitriles. I. Synthesis of New N, N-Disubstituted 4-Amino-1, 1-dicyanobuta-1, 3-dienesA useful and efficient method for the synthesis of 4-amino-1, 1-dicyanobuta-1, 3-dienes 10-20 based on the iminoformylation reaction of crotonnitriles 7-9 with the system triethyl orthoformate/secondary amine in the presence of an acidic catalyst is described. This novel route to the title compounds yields products which are easy to isolate and to purify and also allows to prepare the hitherto unknown N-aryl substituted 4-amino-1, 1-dicyanobuta-1, 3-dienes. Hence it is advantageous as compared to existing iminoformylation reactions of crotonnitriles using formamide acetals.
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  • 127
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 589-594 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass Spectrometric Studies on 16, 17-Amino Alcohols of 3-Methoxy-1,3,5(10)-estratrieneThe electron impact ionization mass spectra of the four isomeric 16, 17-amino alcohols of 3-methoxy-1, 3, 5(10)-estratriene and their N-acetyl and N, O-diacetyl derivatives have been studied. The mass spectra of the isomeric amino alcohols are similar, whereas those of the isomeric N-acetyl and N, O-diacetyl derivatives show some differences depending on the configuration of the substituents in positions 16 and 17. Possibilities of mass spectrometric differentiation between the isomers are discussed.
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  • 128
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 580-588 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reversible Photoisomerizations of Sulfophthalein Indicator Dyes. IV. Stopped Flow Investigations on the Mechanism of the Base Induced Sulton Ring OpeningThe colour formation of rapidly mixed solutions of bromo thymol blue and organic bases in toluene obeys a biexponential rate law. The most probable reaction sequence is: Sulton (colourless) + base ⇌ ring opened H-bridged complex (λmax ≈ 420 nm) ⇌ H-bridged ion pair (λmax ≈ 400 nm). Alternative reaction schemes of the same complexity could be ruled out though the underlying kinetic problem is underdetermined. As a generalizing conclusion it is stated that valuable mechanistic and kinetic information may be derived from underdetermined kinetic problems by calculating the ranges of physically meaningful solutions for the unknowns which are compatible with the particular kinetic schemes instead of the unavailable singular solutions.
    Additional Material: 3 Ill.
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  • 129
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 595-603 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinyl Polymerization Initiated by Reducing Compounds of Transition Metals. VII. Polymerization of Methyl Methacrylate in the Presence of Molybdenum(III) Chloride/Sulfoxide SystemsThe polymerization of methyl methacrylate initiated by the molybdenum(III) chloride/dimethyl sulfoxide redox system was carried out at 70° in 1, 4-dioxane. The rate of polymerization can be described by the equation Rp = k · [MoCl3]0,5 · [DMSO]0,5 · [MMA]1,0. The overall activation energy was estimated to be 36.0 kJ/mol. It was found that diethyl, dipropyl, dibutyl, diphenyl and dibenzyl sulfoxides could also initiate the polymerization of methyl methacrylate in the presence of molybdenum(III) chloride, whereas vanadium(II) chloride, vanadium(III) chloride, titanium(III) chloride and chromium(II) acetate are inactive in combination with sulfoxides.
    Additional Material: 7 Ill.
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  • 130
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 604-608 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Synthesis of Substituted 4-Amino-1, 3-thiazolesIn the 5-position substituted 4-amino-2-alkylthio-1, 3-thiazoles are prepared in good yields from N-nitro-amidino-dithiocarbamates 1 and α-halogen-carbonylcompounds or chloracetonitrile. 1 reacts with 1, 3-dichlor-acetone under formation of adequate bis(1, 3-thiazolyl)ketones.According to the same principle the reaction of the dipotassium salt of the N-nitro-amidino-dithiocarbimidic acid 7 with two equivalents of the α-halogen-carbonylcompound yields 4-amino-5-benzoyl-2-(benzoyl-methylthio)-1, 3-thiazoles.
    Additional Material: 3 Tab.
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  • 131
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 609-615 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Substituted 5-Amino-1,2,4-triazolesN-Nitro-amidino-dithiocarbimidic acid dimethylester 1 reacts with monosubstituted hydrazines under formation of the substituted 5-amino-1, 2, 4-triazoles. Disubstituted hydrazines give under the same conditions N-nitro-amidino-S-methyl-isothiosemicarbazides.The reaction of some more hydrazine derivatives with 1 yields the adequate substituted 1, 2, 4-triazoles.
    Additional Material: 4 Tab.
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  • 132
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985) 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 133
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 705-717 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reaction of Chloranil with Cyanide Ions - an ESR StudyThe reaction of chloranil 1 with cyanide ions in acetonitrile and methanol solutions has been studied. The ESR Spectra revealed the formation of semiquinone anion radicals 7,8, and 9. The latter has been found as its protonated form in methanol only. In addition, both 1 and 2,3-dicyano-5,6-dichloro-1,4-benzoquinone 4 gave tetracyanoethylene anion radicals 6 upon reaction with cyanide ions in acetonitrile. Using 13C-labelled cyanide 6 was shown to originate from the fragmentation of the cyanide addition product to 4. Using the spin trapping technique it was found that no cyanyl free radicals are formed during the thermal reaction of either 1 or 4 with cyanide ions.
    Additional Material: 6 Ill.
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  • 134
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 718-722 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of 4-chloromethyl-1,3-dioxolan-2one (1) with phenol in the presence of potassium carbonate was studied and found to yield 4-phenoxymethyl-1,3-dioxolan-2one (2) and 3-phenoxypropan-1,2-diol (3). The latter compound 3 was also found to be formed as the main product in the reaction of 1, phenol and sodium hydroxide at a temperature higher than 90°C.The effect of various factors on the reaction course and the yield of 2 and 3 was examined.It was found that the reaction studied can be extended to those of difunctional phenols such as 2,2-di(4-hydroxyphenyl)-propane producing the corresponding tetrahydroxyderivative - 2,2-bis-[4-(2,3-dihydroxypropoxy)phenyl]propane.
    Additional Material: 1 Tab.
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  • 135
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 731-738 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constants of hydrolysis of 2-[2-(ω-hydroxyalkoxy)alkyl]-substituted 1,3-dioxolanes and 1,3-dioxanes (1-6) in aqueous HCl solution were determined. For two selected acetals, the parameters of active complexes were also evaluated. The acetals studied were found to be more stable than 2-alkyl-substituted 1,3-dioxolanes and 1,3-dioxanes. The presence of ether-oxygen in β-position with respect to the acetal grouping in molecules of 2-[2-(ω-hydroxyalkoxy)alkyl]-substituted 1,3-dioxolanes and 1,3-dioxanes was the stability determining factor.
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  • 136
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 31P-N.M.R. Investigation and Alkylation of N-Hetaryl-triphenylphosphanimides: Estimation of σ--Constants for Several N-Ring Systems from the 31P Chemical ShiftsOn the basis of a Hammett-lide relationship we have used the 31P chemical shifts of N-hetaryl-triphenylphosphanimides 2 to estimate σ--constants resp. σ--differences of several N-heteroaromatic rings. The electron-withdrawing influence of these rings on the P chemical shift is additionally increased by a short-range electrical field and magnetic anisotropy effect respectively in case the phosphazene group is linked with the α-position of the hetarene. If one aza substituent is neighbouring to the detector group, this through space effect leads to a downfield shift of about 7 ppm. All compounds are alkylated with methyliocide at the ring N atoms and give the quaternary salts 3. The pyridine-N-oxide derivative 2n exists in the open-chain form and reacts with methyliodide at the O atom.
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  • 137
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A rapid and efficient preparation of 1,3,5-triphenylhexahydro-sym-triazine (10) using paraformaldehyde is reported. The trimeric nature of the compound and its structure in solid state, where a biaxial chair conformation is favoured, are conclusively shown by X-ray diffraction analysis. A recent report on a preparation of 1,3-diphenyl-1,3-diazetidine is invalidated.
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  • 138
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on Spin-Trapping Kineties in Radical Systems with Different Reactivity. Photolyses of α-Phenylbenzoine in the Presence of Benzylideneter. -butylamine N-oxideAs a model system to study the spin-trapping kinetics of systems forming two radicals of different reactivity α-phenylbenzoine (PhB) was chosen. The photolysis of PhB forms benzoyl (B·) and diphenylketylradikals (K·), respectively, which can be trapped by benzylidene-tert-butyl-amine N-oxide (PBN), as a spin trap. The rate constants of radical addition to PBN and their reactions with the spin adducts were determined by means of flash photolysis and kinetic calculations of the PBN concentration dependence. For B· and K· addtion rate constants to PBN of k1 = 8,1 × 105 M-1s-1, and k2 = 5,8 · 104 M-1s-1, respectively, were found. The rate constants for the reactions of B· and K· with the spin adducts are in the order of 109…1010 M-1s-1.
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  • 139
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 109-116 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of 1,3,4,-Oxadiazol-2-carboxylic Acid DerivativesThe synthesis of 5-substituted-1,2,4-oxadiazol-2-carboxylic acid derivatives 3a-g and 4a-g by cyclodehydratation of diacylhydrazines 1a-g and 2a-g are described. Further derivatives 6 to 9 are obtained from 1,3,4-oxadiazol-2-carboxethyl esters 3.
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  • 140
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 129-132 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Ethoxyhydroquinazolinone by Attack of an Estercarbonyloxygen at a Cyano GroupBy the reaction of ethyl-2-oxo-cyclohexanecarboxylate with cyan amide 4-ethoxyhexahydroquinazolin-2-one (12) is formed. Butyl-2-oxo-cyclopentanecarboxylate and cyan amide yield butyl-3-cyanamino-cyclopent-1-en-carboxylate (14). 2-Oxocyclohexane-carboxamide (1) and ethyl-cyanoacetate form with sodiumhydroxide 4-cyano-octahydroisoquinolin-1, 3-dione (17) and with ammonium acetate ethyl cyclohexylidene-cyanoacetate-2-carboxamide (18). 18 and ammonia, hydrazine, or cyclohexylamine form the salts of cyanohydroquinazolindione 20a-c, respectively.
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  • 141
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    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects in 13C- N. M. R. Spectra of Diastereomeric Chalcone Dihalogenides. V. Synthesis, Stereochemistry and Spectroscopy of Chalcone FluorohydrinesChalcone fluorohydrins 1 and diastereomeric pairs of chalcone chlorohydrins 2 as standards are investigated in the i.r., 1H, 19F, and 13C n m. r. spectroscopy field. The substituent dependence of the spectral parameters is discussed.The assignment of conformation and configuration on the basis of vicinal 1H—1H, 1H—19F, and 1H—13C coupling constants is determined.
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 156-160 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polarographic Investigations of Quinoxaline-N-oxides
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  • 143
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    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 169-173 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-N.M.R. Spectroscopic Investigations of 2-, 4-, and 6-Brominated Cholest-4-en-3-one Derivatives
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  • 144
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 301-315 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A new finite element technique for calculating energy release rates is presented. An explicit expression for energy changes due to virtual crack extensions is formulated based on a variation of isoparametric element mappings. Energy release rates are calculated directly from integral expressions evaluated over singular quarter-point isoparametric elements surrounding the crack tip. Since the energy release rates are expressed in variational form, there is no need for the analyst to select a small finite crack extension to simulate a virtual crack extension. The method is shown to produce very accurate solutions even with fairly coarse element meshes. A similar technique for mixed-mode fracture based on mutual potential energy release rates is described.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 386-386 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 146
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 387-388 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 147
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    International Journal for Numerical Methods in Engineering 21 (1985) 
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    Keywords: Engineering ; Engineering General
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 437-449 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper extends the earlier work by the present authors for a single embedded crack in an infinite solid and presents a solution to the problem of multiple coplanar cracks in an infinite medium. An alternating method in conjunction with an analytical solution for a single crack is used to determine the stress intensity factors for interacting multiple coplanar embedded cracks in an infinite body. The alternating method, as implemented here, leads to a highly accurate evaluation of the appropriate stress intensity factors.
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  • 149
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 421-435 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A finite element is developed for the three-dimensional deformation of a circular ring. The derivation is based on ring theory. The unique feature of the element is that it provides for coupling between the in-plane and out-of-plane loads and deflections. The element is derived in terms of polar co-ordinates so that no co-ordinate transformation is needed to assemble the elements. Three ring deflection problems are solved using an assembly of the elements. Two of the solutions are compared with analytical results and one is compared with experimental results. The comparisons verify the theory.
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  • 150
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 543-554 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A procedure to discretize explicit enthalpy formulations for one-dimensional planar phase change problems is derived, which removes numerical oscillations in temperature and phase front position. The technique is based on an enthalpy balance for the control volume containing the phase front in combination with linearized temperature profiles near the phase front. A continuous casting solidification problem and a problem with known analytical solution are applied to demonstrate the effect of the scheme.
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  • 151
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 585-600 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A generally applicable and simple joint/interface element for three- and two-dimensional finite element analysis is presented. The proposed element can model joints/interfaces between solid finite elements and shell finite elements. The derivation of the joint element stiffness is presented and algorithms for the treatment of nonlinear joint behaviour discussed. The performance of the element is tested on typical problems involving shell-to-shell and shell-to-solid interfaces.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 617-635 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A 48 degrees-of-freedom quadrilateral element, including the effect of both material and geometric nonlinearities, is formulated and appropriate numerical procedures are adopted for the development of a systematic and efficient approach for the static nonlinear analysis of general shell structures. The element surface is described by a variable-order polynomial in curvilinear co-ordinates. The displacement functions are described by bicubic Hermitian polynomials in curvilinear co-ordinates. Without being confined to the assumption of axisymmetry, this formulation allows for the treatment of shells with a more general shape and with a complex spread of plastic zones. In the formulation for geometric nonlinearity, the total Lagrangian approach is adopted. Only small strains and small rotations are allowed. In the formulation for plastic deformation, the concept of a layered element model is used. In the inelastic range, the material is assumed to obey the Von Mises yield criterion and the Prandtl-Reuss flow rule. A tangential stiffness formulation is combined with the modified Newton-Raphson iteration method for the solution of nonlinear problems. A systematic choice of examples ranging from fiat plates to cylindrical panels and to spherical caps is solved and compared with available solutions to evaluate the recommended formulations and procedures in terms of their accuracy and efficiency.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 683-689 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: As an approximation for the mechanism behind noise emission from a rock drilling rod, the transient damped vibrations of a beam (the drilling rod) in bending and shear is studied. At one end the beam is supported by a distributed damped Winkler-type foundation. In order to determine required transfer function from an applied moment at the other end of the beam, it is divided into two finite elements. Each element is treated as a uniform Rayleigh-Timoshenko beam in an ambient medium. The fast Fourier transform (FFT) technique is utilized. Good agreement between calculated and measured strains is obtained. A single-figure measure which is approximately proportional to the sound power radiated from the vibrating beam is calculated for different damping materials at the supported end. It is found that a relatively high value of the stiffness of the Winkler-type foundation is needed if a significant level of reduction in the sound power radiated from the beam is to be achieved.
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  • 154
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 713-721 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: At present there are many general methods of approximating a possibly nonlinear operator equation by a finite equation system. The most commonly applied methods are the finite element and the finite difference. Numerous papers (e.g. References 9 and 10) have dealt with a comparison of these methods.In Reference 12 the Galerkin finite difference method (GFDM) is developed. The GFDM is a special finite element method designed t o solve nonlinear and possibly coupled partial differential equations numerically. It consists of a finite difference scheme derived from a Galerkin finite element method through the use of special local basis functions and a special grid.In this paper, we are concerned with extending the GFDM to derive ‘normal’ difference schemes. e.g. five-point schemes on two-dimensional domains for a general class of operators, even in nonlinear cases.Using GFDM or the finite element method on two-dimensional regions generally leads to at least 7- or 9-point schemes as well as expensive approximations of the nonlinear terms. Often, numerical integration is necessary. These computational costs are due to the non-orthogonality of the continuous and differentiable local basis functions that are needed in this case.The basic idea of the multi-bases approaches, which are the major concern in this paper11, is to reduce the smoothnessproperties ofthelocal basis functions in favour oftheir orthogonality. Thiscan beachieved with the help of so-called transfer operators which map the non-orthogonal and differentiable basis onto an only bounded but orthogonal basis.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 777-778 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 156
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 775-776 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 763-774 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We derive a closed-form expression for the change in the variational indicator of a finite element mesh with respect to perturbations in nodal point co-ordinates. The expression is evaluated very effectively from standard finite element data obtained in one solution, and may be easily programmed as part of a general finite element code. We present the derivation for two- and three-dimensional isoparametric elements used in linear and nonlincar elasticity. The expression has practical applications in the computation of stress intensity factors in fracture mechanics and in the determination of the ‘optimal’ mesh with a given element-node connectivity. We demonstrate both applications by accurately determining the stress intensity factor of a Mode I crack using a finite element mesh which was improved using mesh optimization.
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  • 158
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 825-835 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Many plane stress finite elements which can exactly represent rigid-body and constant-strain modes are too stiff in their response to the simple flexural action of a beam. This problem has received considerable interest. In this paper we explore a new interpretation of the problem and show that the poor bending response of the original 4-node plane stress quadrilateral can be quantitatively predicted by an error model.
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    International Journal for Numerical Methods in Engineering 21 (1985) 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1361-1362 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1345-1359 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Introduced herein is a generalization of Newmark's time marching integration scheme, called the β-m method. Like the SSpj method (introduced in Parts 1 and 2 of this series), the β-m method provides a gcneral single-step scheme applicable to any set of initial value problems. The method is specialized by specifying the method order m along with rn integration parameters, β0, β1, …, βm-1. For a particular choice of m, the integration parameters provide a subfamily of methods which control accuracy and stability, as well as offering options for explicit or implicit algorithms. For the most part, attention is focused on the application to structural dynamic equations. Most well-known methods (e.g. Newmark, Wilson, Houbolt, etc.) are shown to be special cases within the β-m family. Hence, one computationally efficient and surprisingly simple algorithm unifies old and new methods. Stability and accuracy analyses are presented for method orders m = 2, 3 and 4 to determine optimal parameters for implicit and explicit schemes, along with numerical verification.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1381-1390 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A numerical scheme has been constructed to simulate the imposition of a step in heat transfer at the surface of a multi-layered substrate. The numerical simulation of this process is carried out by applying an extended version of the Keller Box-Scheme to multi-layered diffusion problems. Numerical calculations show that accurate choice of length and time-scales is critical in determining the behaviour of the heat flow through the substrate. Thus, the results from the numerical simulations are of value to the experimentalist, particularly in determining the accurate shape of the response curves which enable experimental apparatus to be designed effectively. The proposed scheme yields heat fluxes as accurately as temperatures, and can be easily adapted to other related applications.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1521-1533 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A simple and logical finite element formulation is presented for the analysis of rings and sectors, with Timoshenko effects. The elemental properties are derived from the governing differential equation of motion using the Galerkin method. A quintic polynomial, satisfying the compatibility of derivatives up to second order, has been used for the ring finite element. The interpolating function is the same as for a thin ring. The efficiency of the formulation has been illustrated by the numerical results presented.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1547-1553 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: For about a decade, each and every researcher who used isoparametric quadratic elements to solve fracture mechanics problems employed only incomplete versions of these elements. Although complete formulations of isoparametric elements are almost as available as incomplete ones in general-purpose finite element computer programs, no attempt to use complete formulations has been seen yet. The purpose of this paper is to show how the complete quadratic isoparametric elements can be employed in the field of fracture mechanics.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1709-1727 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A method is presented which enables the calculation of the settlement behaviour of circular or general loadings on horizontally layered soils which undergo secondary or ‘creep’ consolidation. The method of analysis involves the use of Hankel or double Fourier transforms to simplify the equations governing the consolidation process. This leads to great savings in the preparation of data and the amount of computer storage needed to solve problems involving three-dimensional loadings since such problems are essentially reduced to that of one spatial dimension: Solutions are then obtained by a ‘forward marching’ process where solutions at a particular time are found from those at a previous time. A method is presented which eliminates the need to store the solutions at all previous time steps, and is therefore very efficient. The theory is illustrated by examples of the behaviour of rectangular and circular loadings on layered soil profiles.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1749-1758 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A technique is described in which global approximations are used to improve the accuracy of the finite element method. The technique is theoretically based on two corollaries to the Lax-Milgram lemma which are presented in this paper. Basically, the technique consists of factoring the unknown function for which an approximation is desired into the product of a global approximation and a second unknown function. Finite element methods are appropriately applied to obtain an approximation to the second unknown function. The approximation to the original function then consists of the product of the specified global approximation and the approximation to the second unknown function. The advantage that finite element methods possess with respect to obtaining banded matrices is preserved in this technique. In addition, numerical examples indicate that the technique's accuracy is as much as a factor of fifty better than the accuracy obtained by directly applying a finite element method to approximate the original function.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1791-1802 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An efficient block overrelaxation algorithm is presented for the solution of the steady-state dam seepage problem. The formulation of Alt is used in conjunction with a finite element method on a fixed mesh to obtain a finite dimensional problem which is then solved by the algorithm. Some similarities of the formulation and the residual flow method of Desai are also discussed. Numerical results are compared with results of other authors.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1938-1939 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 169
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1925-1934 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Material modelling requirements for accurate stress fields in a nonuniform anisotropic composite are established for all six components of stress at a material point. The gauge section from a conical involute structure tested in an earlier investigation provides the case data for this modelling study. Stress results from a tricubic Hermite finite element model are shown to be in agreement with another computational analysis by Pagano using a Reissner energy formulation. Comparisons are made in the interior and at a corner with high interlaminar stress gradients. The small, but critical, matrix dominated stress components are shown to be very sensitive to modelling material orientation changes within each finite element. Uniform stress accuracy was obtained using distribution functions for material orientation of the same degree as the displacement functions, an isoparametric material geometry model.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 2013-2025 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: An effective technique is presented for recovering surface tractions and distributed reaction forces from finite element displacement solutions of structural mechanics problems. Nodal values of surface tractions and assumed trial functions are used to represent the distribution of surface stresses. Equations obtained from the familiar Galerkin formulation are used to compute the nodal traction values. The method is demonstrated to be efficient and highly accurate, even in the presence of jump conditions or singularities. Extensions of the method are possible for recovering secondary solution variables in non-structural finite element applications.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1941-1955 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This paper compares the performance of the SS22 and SS23 (References 1 and 2) single step algorithms for the numerical solution of the second-order structural dynamic equation and a related new algorithm SS32B applied to the equivalent first-order system, with sine and step forcing functions. Various aspects of stability relevant to these equations are discussed.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1957-1969 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A method for obtaining difference equations from differential equations which has previously been applied to ordinary differential equations is here applied to the time-dependent heat conduction equation as a representative example of parabolic partial differential equations. Explicit difference equations are derived which are stable for all values of αΔt/Δ2 and are also accurate. Implicit-algorithms with improved accuracy are also derived. Problems in cartesian and cylindrical co-ordinates are treated.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 2128-2129 
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 2157-2168 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: We present a method which makes it possible to apply the idea of iterated defect correction to finite difference methods for the numerical treatment of partial differential equations. The method yields numerical approximations of very high accuracy for the solution, while the corresponding algebraic systems of equations still have ‘reasonable’ size.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 2201-2219 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A higher-order shear deformation theory is used to analyse laminated anisotropic composite plates for deflections, stresses, natural frequencies and buckling loads. The theory accounts for parabolic distribution of the transverse shear stresses, and requires no shear correction coefficients. A displacement finite element model of the theory is developed, and applications of the element to bending, Vibration and stability of laminated plates are discussed. The present solutions are compared with those obtained using the classical plate theory and the three-dimensional elasticity theory.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 2289-2302 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Bernoulli-Euler theory and Bessel functions are used to obtain explicit expressions for the exact dynamic stiffnesses for axial, torsional and flexural vibrations of any beam which is tapered such that A varies as yn and GJ and I both vary as y(n + 2), where A, GJ and I have their usual meanings; y = (cx/L) + 1; c is a constant such that c 〉 - 1; L is the length of the beam; and x is the distance from one end of the beam. Numerical checks give better than seven-figure agreement with the stiffnesses obtained by extrapolation from stepped beams with 400 and 500 uniform elements. A procedure is given for calculating the number of natural frequencies exceeded by any trial frequency when the ends of the member are clamped. This enables an existing algorithm to be used to obtain the natural frequencies of structures which contain tapered members.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 2305-2306 
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    Keywords: Engineering ; Engineering General
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    International Journal for Numerical Methods in Engineering 21 (1985) 
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  • 179
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    International Journal for Numerical Methods in Engineering 21 (1985), S. i 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 1-11 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: ‘Dynamic’ or ‘viscous’ relaxation procedures have not gained much popularity in finite element analysis in which the direct (Gaussian elimination) solution dominates. Reasons for this are various - the most important being the rather slow convergence generally achieved for such procedures. However, it is possible to accelerate this quite dramatically and a method of doing so is shown in this paper. With the use of such acceleration and the inherent advantages of greatly reduced storage requirements and simplicity of programming, relaxation procedures promise an exciting possibility for the solution of large two- and three-dimensional problems in both linear and nonlinear ranges.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 13-18 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 37-63 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Structural reanalysis problems, such as in nonlinear finite element analysis or optimum design, involve progressive changes in the global stiffness matrix and its matrix factors. Although many studies have been devoted to the subject of matrix factor modification, most investigations have dealt with the problem separately from sparse matrix methods. This paper introduces a graph-theoretic model for the forward solution procedure which is applicable for identifying the modified entries of the matrix factors due to changes in the original matrix. Applications of this graph-theoretic model to existing refactorization methods are presented. The relation between substructuring and sparse matrix ordering strategies, and their effects on reanalysis are discussed. Modification of a sparse matrix associated with an n × n finite element grid ordered by the nested dissection scheme is analysed.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 19-36 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A numerical method is presented for the design of thin turbomachinery blades with specified whirl velocities across the blade span. The numerical scheme involves iteration between the directs solution of a finite-volume method developed earlier on by Soulis1 and a design solution.The finite-volume method, which is a combination of finite elements and finite differences, solves the three-dimensional, inviscid, steady arid potential flow through turbomachinery blade rows in the incompressible, compressible and transonic flow range. In the design step, the whirl velocity distribution is specified across the blade span (Dirichlet boundary condition). The design procedure yields a new set of co-ordinates for the blade geometry which are used in the next iteration of the direct solution. However, in the present analysis only thin turbomachinery blades are designed, although a fully three-dimensional numerical method is used (the whirl velocity components of the flow field are averaged over the blade suction and pressure surface).The numerical method has been used to design free-vortex thin turbomachinery blades. Results show that the new numerical procedure is a comparatively economic and reliable method for designing thin turbomachinery blades. It may form the baseline for complete three-dimensional turbomachinery blade designs.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 65-88 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A solution procedure for the analysis of planar and axisymmetric-contact- problems involving sticking, frictional sliding and separation under large deformations is presented. The contact conditions are imposed using the total potential of the contact forces with the geometric compatibility conditions, which leads to contact system matrices and force vectors. Some key aspects of the procedure are the contact matrices, the use of distributed tractions on the contact segments for deciding whether a node is sticking, sliding or releasing and the evaluation of the nodal point contact forces. The solutions to various sample problems are presented to demonstrate the applicability of the algorithm.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 89-104 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Relations between displacement models using reduced integration and hybrid mixed models based on the Hellinger-Reissner and the Herrmann principles have been investigated. Five different isoparametric elements are considered for the case of plane stress, plane strain and plate bending elasticity problems.It is proved that the following relations hold for both models, provided the number of terms of a polynomial expressing the stress or strain component in the formulation of the mixed models is equal to the number of integration points of the reduced integration. If the stiffness matrix of the mixed model is evaluated by the identical integration rule with the reduced integration, the stiffness matrices of both models are identical. Thus, both models are equivalent, if the stiffness matrix of the mixed model is integrated exactly by the identical integration rule with the reduced integration.The displacement models using uniform reduced integration and selective reduced integration are equivalent to the mixed models based on the Hellinger-Reissner and the Herrmann principles except for the 6-node element, respectively.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 105-114 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A new three-noded triangular element for plate bending is described. The element is based on an earlier stress-smoothed triangular element due to Razzaque,1 but extra internal ‘bubble’ functions are included to make it more flexible. The accuracy of the new element is compared with that of a number of other high-performance triangular elements. It is concluded that the present element and that due to Hansen, Bergan and Syvertsen2 are the two most accurate triangular thin plate elements currently available. The extra lines of FORTRAN required to convert Razzaque's shape function subroutine to that for the new element are given, thus making the new element easy to implement in any general-purpose finite element program.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 115-129 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A vector boundary integral equation (BIE) formulation and numerical solution procedure is presented for problems of three-dimensional elastic wave radiation and scattering from arbitrarily shaped obstacles. The formulation is explicitly in terms of surface traction and displacement, rather than wave potentials, and the BIE on which numerical work is based is written in a form entirely free of Cauchy principal value integrals. Indeed, the subsequent computational process, based on quadratic isoparametric boundary elements, renders all integrals free of singularities, so that ordinary Gaussian quadrature may be used. Numerical examples include scattering from spherical surfaces and radiation from a cube.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 163-168 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A fully discrete stability and accuracy analysis of some algorithms for the one-dimensional heat equation is presented. Results illustrate that 2-pass explicit schemes which simultaneously employ lumped and coupled capacity matrices are capable of improved performance over the standard 1-pass explicit scheme.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 169-182 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A general matrix operator is established for solving linear boundary value problems in slip-line field theory. The operator will enable a wider class of problems to be solved than were previously possible with the matrix slip-line field technique. As an illustration, a range of solutions are generated involving the previously intractable Coulomb friction boundary condition.
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 193-193 
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 193-193 
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 194-195 
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    International Journal for Numerical Methods in Engineering 21 (1985) 
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 229-238 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 21 (1985), S. 197-209 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Exact expressions are presented for the potentials, at an arbitrary point in space, due to two quadratic distributions in a triangular disc. These expressions are obtained by means of extensions of the analytical techniques previously developed for evaluating the potential integrals for constant and linear distributions. It is shown that the potential due to any quadratic distribution in a triangle may be obtained by using the two expressions derived here, together with an expression for the potential corresponding to a linear distribution. This latter expression was presented in an earlier paper.1 Numerical values obtained through the use of the two expressions are compared with those which result from the numerical evaluation of the potential integrals by triangle quadratures.
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 21 (1985), S. 211-228 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Use of the Green function, for the solution of boundary-value problems, frequently results in singular integral equations. Algorithms are presented for the accurate and efficient treatment of singular kernels frequently encountered in the boundary element method (BEM). They are based upon the use of appropriately weighted Gaussian quadrature formulae, together with numerical geometrical transformations of the region of integration. The use of high-order subdomain expansion functions, for interpolation over nonplanar elements, allows boundary curvature to be accommodated. In particular, the handling of Green functions with logarithmic and r-1 behaviour are detailed. Volume integrals, with r-2 singularity, are outlined. Operations are performed on a simplex, thus resulting in generality and ease of automation. This scheme has been incorporated into boundary element method software and successfully applied to a variety of problems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 197
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 21 (1985), S. 239-265 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper reports a new explicit and conditionally stable finite difference equation for heat conduction. It predicts results with an accuracy comparable with or better than that obtainable by other methods. Stability of operation can be extended to any desired degree by subdividing the basic time step and increasing the number of nodes. Some existing difference equations are special cases of the new equation reported in this paper. The new solution has been tested by calculating the response of a slab to transient and progressive waves whose analytical solutions are known.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 198
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 21 (1985), S. 1577-1581 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An efficient method for solving algebraic equations is given. The linear equations are solved only once and iterations are performed on the non linear equations. If an initial approximation to a desired root is available, then it is utilized in the solution process. Results of some computational experiments are given.
    Type of Medium: Electronic Resource
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  • 199
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 21 (1985), S. 2221-2236 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The problem treated is the integration of singular functions which arise in three-dimensional isoparametric formulations of boundary integral equations. A Taylor expansion in the local parametric co-ordinates is developed for the singular integrand, so allowing singular terms to be integrated in closed form, even for curved surface elements. The remainder integral obtained by subtracting out the worst singularities is integrated by repeated Gaussian quadrature.Two groups of tests are presented. First, the accuracy of the integrations has been checked for plane parallelograms (for which exact solutions have been developed) and for curved elements on a sphere. Secondly, results from complete boundary element calculations based on point collocation have been compared with known analytical solutions to two problems; zonal surface harmonics on a sphere and the capacitance of an ellipsoid. The agreement obtained with few degrees-of-freedom suggests that errors which have previously been attributed to point collocation might have arisen in the numerical integration.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 200
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 21 (1985), S. 2273-2287 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A software system for the automated computer simulation of two-dimensional elastostatic problems by the finite element method is described. This system consists of two parts, automated mesh generation and automated stress analysis. The mesh generation is based on a method in which equilateral triangles are generated successively in the unmeshed region. Automated mesh refinement is carried out in the latter part of the simulation process. The stress analysis is based on the assumed stress hybrid method and the successive over relaxation method. The computer program developed for this paper can generate a succession of increasingly refined triangular meshes until a certain mesh convergence criterion is achieved. The mesh convergence criterion is based on a comparison of nodal stresses in successive analyses until all the stress differences are within a specified tolerance.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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