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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 471-472 (Dec. 2004), p. 390-395 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The effect of died-pressed binders, such as polyvinyl alcohol (PVA), butyl sodium rubber (BSR) and paraffin wax (PW), on green strength, green density, dimensional stability, residue, sintered compact density and mechanical properties of Ti(C,N)-based cermet was investigated. It was found that the types of the binder had a significant impact on the characteristics of the green compact.PVA improved dimensional stability of the green compact due to interaction between binder and particle. The glass transition temperature (Tg) of PVA influenced the forming behavior of Ti(C,N)-based cermet powders during died-pressed processing. Some residual moisture was needed to obtain high green strength. PVA had a gradual burnout with a low char residue in nitrogen. Compared with PVA, the influence of binders BSR and PW was also presented and discussed
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  • 2
    ISSN: 1573-0867
    Keywords: Exchangeable NH 4 + -N ; NO 3 - -N ; nonexchangeable NH 4 + -N ; Fertilizer N Uptake N15-depleted ; 15N isotope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Use of15N-depleted fertilizer materials have been primarily limited to fertilizer recovery studies of short duration. The objective of this study was to determine if15N-depleted fertilizer N could be satisfactorily used as a tracer of residual fertilizer N in plant tissue and various soil N fractions through a corn (Zea mays L.) -winter rye (Secale cereale L.) crop rotation. Nitrogen as15N-depleted (NH4)2SO4 was applied at five rates (0, 84, 168, 252, and 336 kg N ha−1) to corn. Immediately following corn harvest a winter rye cover crop treatment was initiated. Residual fertilizer N was easily detected in the soil NO 3 - -N fraction following corn harvest (140-d after application). Low levels of exchangeable NH 4 + -N (〈2.5 mg kg−1) did not permit accurate isotope-ratio analysis. Fertilizer-derived N recovered in the soil total N fraction following corn harvest was detectable in the 0 to 30-cm depth at each N rate and in the 30 to 60 and 60 to 90-cm depths at the 336 kg ha−1 N rate. Atom %15N concentrations in the nonexchangeable NH 4 + -N fraction did not differ from the control at each N rate. Nitrogen recovery by the winter rye cover crop reduced residual soil NO 3 - -N levels below the 10 kg ha−1 level needed for accurate isotope-ratio analysis. Atom %15N concentrations in the soil total N fraction (approximately one yr after application) were indistinguishable from the control plots below the 168, 252, and 336 kg ha−1 N rate at the 0 to 30, 30 to 60, and 60 to 90-cm depths, respectively. Recovery of residual fertilizer N by the winter rye cover crop was verified by measuring significant decreases in atom %15N concentrations in rye tissue with increasing N rates. The greatest limitation to the use of15N-depleted fertilizer N as a tracer of residual fertilizer N in a corn-rye crop rotation appears to be its detectibility from native soil N in the total N pool.
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  • 3
    ISSN: 1573-2673
    Keywords: Crack ; fracture mechanics ; residual stresses.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The standard definition of the J integral leads to a path dependent value in the presence of a residual stress field, and this gives rise to numerical difficulties in numerical modelling of fracture problems when residual stresses are significant. In this work, a path independent J definition for a crack in a residual stress field is obtained. A number of crack geometries containing residual stresses have been analysed using the finite element method and the results demonstrate that the modified J shows good path-independence which is maintained under a combination of residual stress and mechanical loading. It is also shown that the modified J is equivalent to the stress intensity factor, K, under small scale yielding conditions and provides the intensity of the near crack tip stresses under elastic-plastic conditions. The paper also discusses two issues linked to the numerical modelling of residual stress crack problems-the introduction of a residual stress field into a finite element model and the introduction of a crack into a residual stress field.
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  • 4
    ISSN: 1573-2673
    Keywords: Weibull stress ; cleavage fracture ; fracture mechanics ; finite element analysis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The Weibull stress is widely used as a measure of the probability of cleavage failure. In this work analytical and semi-analytical expressions for the Weibull stress are developed in terms of the remote loading parameters, J or K, and material properties. Results are presented for sharp cracks and notches in elastic and elastic-plastic materials under plane stress and plane strain conditions. The proposed relations enable Weibull stress estimates to be obtained without the need for costly finite element analyses and provide insight into the use of the Weibull stress as a parameter for the prediction of cleavage failure of cracked bodies. The expressions have been verified using finite element techniques and good agreement has been found throughout. The results of the analyses have been used to interpret the mesh size dependence of Weibull stress values obtained from finite element calculations.
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  • 5
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 7
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Third stage larvae ofNecator americanus were radiolabeled with75Se-methionine by two methods. Larvae labeled in aqueous cultures contained 188 and 25 cpm per sheathed and ex-sheathed larva, respectively. Larvae labeled in coproculture incorporated 25 and 18 cpm per sheathed and ex-sheathed larva, respectively. All of the label was decayed in 5 days from larvae labeled in aqueous cultures, whereas appreciable amounts of radioactivity were still detectable at day 7 of chase peroid in coproculture labeled larvae.
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  • 8
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A probabilistic analysis of fatigue crack growth, fatigue life and reliability of elastic structural components is presented on the basis of fracture mechanics and the theory of random process. Both the material resistance to fatigue crack growth and the time-history of the stress are assumed to be random. The stress in an elastic structural component is proportional to the corresponding displacement response that is governed either by a linear differential equation for a linear structural system or by a nonlinear differential equation for a nonlinear structural system due to the plasticity other components. Analytical expressions are obtained for the special case that the random stress process is narrow-banded. Numerical examples are given for the randomized Paris-Erdogan type crack growth law to illustrate the procedures and the results are compared with those obtained from simulation to validate the stochastic approach.
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  • 9
    ISSN: 1572-8943
    Keywords: cadmium coordination ; crystal structure ; enthalpy of solution ; lattice energy ; lattice enthalpy ; NTO salt ; preparation ; standard enthalpy of dehydration ; standard enthalpy of formation ; thermal decomposition mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract [Cd(NTO)4Cd(H2O)6]·4H2O was prepared by mixing the aqueous solution of 3-nitro-1,2,4-triazol-5-one and cadmium carbonate in excess. The single crystal structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, space group C2/c with crystal parameters of a=2.1229(3) nm, b=0.6261(8) nm, c=2.1165(3) nm, β=90.602(7)°, V=2.977(6) nm3, Z=4, Dc=2.055 g·cm−3, μ=15.45 cm−1, F(000)=1824, λ(MoKα)=0.071073 nm. The final R is 0.0282. Based on the results of thermal analysis, the thermal decomposition mechanism of [Cd(NTO)4Cd(H2O)6]·4H2O was derived. From measurements of the enthalpy of solution of [Cd(NTO)4Cd(H2O)6]·4H2O in water at 298.15 K, the standard enthalpy of formation, lattice energy, lattice enthalpy and standard enthalpy of dehydration have been determined as -(1747.8±4.8), -2394, -2414 and 313.6 kJ mol−1 respectively.
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  • 10
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  A method for the elimination of matrix effects was developed for the determination of trace amounts of silicon by microwave plasma torch atomic emission spectrometry (MPT-AES). The sample solution was introduced into the MPT with a pneumatic nebulizer (PN). When Ar was used as both carrier and support gas, a detection limit of 10.8 ng/ml was obtained. The precision was 4.2% (RSD). The characteristics of the emission spectrum of silicon in MPT was studied in detail. The interference of some concomitant cations with the silicon emission was eliminated by incorporation of a cation-exchange column into the flow injection system. The method has been applied to analyze some practical samples and the results obtained are satisfactory.
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