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91.
Jon T. Carter Paul E. Krajewski Ravi Verma 《JOM Journal of the Minerals, Metals and Materials Society》2008,60(11):77-81
The hot blow forming of magnesium sheet offers significant opportunity for forming complex, lightweight parts for automotive
applications. This paper characterizes the elevated-temperature formability of AZ31 magnesium sheet materials and the effect
of processing conditions on the performance of these materials. In addition, magnesium sheet application development at General
Motors Corporation is reviewed. 相似文献
92.
Toshihiko Hoshide Junpei Fujita 《Journal of Materials Engineering and Performance》2008,17(5):627-632
Strength of ground ceramics may be affected by residual stress as well as surface flaws induced by grinding. Strength prediction
for ground ceramics is convenient for mechanical design of ceramic components. In this article, a numerical procedure based
on fracture mechanics was proposed to estimate strength distribution of ground ceramics by considering grinding-induced residual
stress. Bending strength and residual stress of ground ceramics were measured for three grinding-conditions. By comparison
of simulated results with experimental ones, it was revealed that strength characteristics in experiments were well simulated
by using the proposed procedure. 相似文献
93.
Two lignite samples, Beulah No. 3 and Big Brown No. 1, were liquefied at 420 °C using H2 and synthesis gas to determine the optimum beneficial amount of H2S in the batch autoclave reactor. Under the conditions employed, 50–100 psi partial pressure of H2S, nominally 4–10 wt% of daf lignite, was optimum for both samples. Synthesis gas outperformed H2 with and without H2S for the liquefaction of the two coals. 相似文献
94.
Lewis V. McCarty Richard Donelson Robert f. Hehemann 《Metallurgical and Materials Transactions A》1991,22(1):969-974
A mathematical model describes the carburization kinetics of tungsten powders mixed with carbon and heated in hydrogen. It
is based on diffusion of carbon through a shell of WC growing into particles which are modeled as spheres. The activation
energy is 58 kcal/mole in the temperature range 1056 to 1833 °C. Hydrogen gas is important to transport carbon as methane
or acetylene, but increased hydrogen pressure increases the rate of carburization so little that an adsorbed species such
as CH probably controls the carbon concentration at the particle surface.
Formerly with the Lamp Metals Laboratory, deceased, was Professor of Metallurgy at Case Western Reserve University Cleveland
OH. 相似文献
95.
Nietzel Michael T.; Russell Robert L.; Hemmings Kelly A.; Gretter Monica L. 《Canadian Metallurgical Quarterly》1987,55(2):156
[Correction Notice: An erratum for this article was reported in Vol 55(3) of Journal of Consulting and Clinical Psychology (see record 2008-10745-001). The data presented in Table 2 were incorrect because a row and a column were inadvertently omitted. The corrected Table 2 appears in the erratum.] This study used meta-analysis to study the clinical significance of psychotherapy for symptoms of unipolar depression. The following questions were addressed: How similar is the posttherapy adjustment of depressed adults to that of nondepressed adults? Is this adjustment maintained at follow-up? What dimensions of treatment, therapists, or design are associated with clinical significance? Using the Beck Depression Inventory (BDI), we calculated composite BDI norms from 28 published studies. Sixty effect sizes (from 31 outcome studies utilizing the BDI) were calculated. The results indicated that psychotherapy produces outcomes that have moderate clinical significance and that are well-maintained at follow-up, that individual therapy is associated with greater clinical significance than group treatment, and that type of therapy is not related to improvement. Alternative approaches for operationalizing clinical significance as the return of individuals to normal levels of functioning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
In the testing of mine monitoring systems, a software package was developed for the mine monitoring test facility designed at West Virginia University. The software establishes delay times of sensor input to annunciation for single alarms and multiple simultaneous alarms. The alarm measurement techniques for the test fixture are described, as is the software developed to analyze and graph monitoring system response data. Also included is the analysis capability of the facility, the criteria for evaluating mine monitoring systems, and typical test data from a sample system. 相似文献
97.
98.
Zirconium(IV) tungstoiodophosphate has been synthesized under a variety of conditions. The most chemically and thermally stable
sample is prepared by adding a mixture of aqueous solutions of 0·5 mol L−1 sodium tungstate, potassium iodate and 1 mol L−1 orthophosphoric acid to aqueous solution of 0·1 mol L−1 zirconium(IV) oxychloride. Its ion exchange capacity for Na+ and K+ was found to be 2·20 and 2·35 meq g−1 dry exchanger, respectively. The material has been characterized on the basis of chemical composition, pH titration, Fourier
transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The effect on the exchange capacity of drying the exchanger
at different temperatures has been studied. The analytical importance of the material has been established by quantitative
separation of Pb2+ from other metal ions. 相似文献
99.
Jonathan P. Belnoue Giang D. Nguyen Alexander M. Korsunsky 《International Journal of Fracture》2007,144(1):53-60
This paper presents a new 1-D non-local damage-plasticity deformation model for ductile materials. It uses the thermodynamic
framework described in Houlsby and Puzrin (2000) and holds, nevertheless, some similarities with Lemaitre’s (1971) approach.
A 1D finite element (FE) model of a bar fixed at one end and loaded in tension at the other end is introduced. This simple
model demonstrates how the approach can be implemented within the finite element framework, and that it is capable of capturing
both the pre-peak hardening and post-peak softening (generally responsible for models instability) due to damage-induced stiffness
and strength reduction characteristic of ductile materials. It is also shown that the approach has further advantages of achieving
some degree of mesh independence, and of being able to capture deformation size effects. Finally, it is illustrated how the
model permits the calculation of essential work of rupture (EWR), i.e. the specific energy per unit cross-sectional area that
is needed to cause tensile failure of a specimen. 相似文献
100.
Yewang Su Baohua Ji Yonggang Huang Kehchih Hwang 《Journal of Materials Science》2007,42(21):8885-8893
Wet adhesion is widely adopted in biological adhesion systems in nature. Wet adhesion is studied in this paper with the focus
on the effect of different contact shapes (flat, concave, convex, and ring-like) on the adhesion force. The evolution of the
liquid bridge between a fiber tip and substrate during the detaching process shows two transition points. The first transition
from the radius-controlled to the contact-angle controlled process is critical to influence the strength and robustness of
adhesion. We show that a concave shape is more effective than a flat one, while a convex shape has no advantage. A ring-like
contact shape has advantages in a hydrophobic environment and on a rough surface. 相似文献