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91.
Creep tests on a small scale have the potential to be used without significant removal of material or in areas where the available material is limited. In this paper an extension of the modified Monkman-Grant model for the prediction of the creep rupture time using Small Punch Creep Tests (SPCT) is investigated. This test basically consists of punching, under constant load, a small size specimen (10×10×0.5 mm) with the ends fixed. For this purpose an AZ31B magnesium alloy, taking a test temperature of 150?ºC, has been selected. The Monkman-Grant relation is a predictive model, initially developed for uniaxial creep tests, which can be used to predict the rupture time of tests which have been interrupted once secondary stage of creep has been reached. The proposed extension of the Monkman-Grant model for SPCT is based on the definition of the Minimum Relative Punch Displacement Rate. The experimental techniques and data analysis, involving small punch testing, are explained in detail. The proposed predictive model allows the test times of small punch testing to be reduced and it can be directly applied to predict the failure time from an interrupted test at the time when the Minimum Relative Punch Displacement Rate is reached. Good correlations are obtained by comparing the failure time from the proposed Monkman-Grant extension with the experimental failure time. 相似文献
92.
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94.
Albert Puig-Arànega Javier Burgos Salvatore Cito Ildefonso Cuesta 《International Journal of Computational Fluid Dynamics》2015,29(9-10):434-446
This paper analyses the effects of considering non-reflective (characteristic boundary conditions) versus reflective boundary conditions (BCs) on the flow past a square object. We observe a clear dependence of the force exerted over the obstacle on the choice of BCs. Recirculation lengths, lift and drag coefficients, phase diagrams and streamlines for several angles of incidence are compared for a range of low Reynolds numbers (50–150) and two different values of the ratio of the object cross section to the channel width, 1/8 and 1/16. We remark distinct effects depending on the combination of BCs used at the inlet and at the outlet. 相似文献
95.
A simple, rapid and sensitive liquid chromatographic method using a refractive index detector has been developed and validated for identification and quantification of β-cyclodextrin in milk, cream and butter. The chromatographic system consists of a YMC ODS-AQ column packed with C18 reversed phase silica packing material as stationary phase using a mixture of methanol and water 7:93% (v/v) as the mobile phase. Linearity was established for the β-cyclodextrin concentration in the range 0.01–4 mg mL?1, with a coefficient (r) of 0.9998. Repeatability of the method was assessed; the coefficient of variation for β-cyclodextrin range were 1.24, 3.01, and 5.36% for milk, cream and butter. Recoveries ranged between 99.91 and 94.53%. This method was highly reproducible and reliable for quantification of treated milk with β-cyclodextrin for removal cholesterol from the milk fat. 相似文献
96.
Marta Izquierdo Benedikt Platzer Anton J. Stasyuk Olga A. Stasyuk Alexander A. Voityuk Sergio Cuesta Miquel Sol Dirk M. Guldi Nazario Martín 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7006-7011
The synthesis and characterization of a covalent all‐fullerene C60‐Lu3N@Ih‐C80 electron donor–acceptor conjugate has been realized by sequential 1,3‐dipolar cycloaddition reactions of azomethine ylides on Lu3N@Ih‐C80 and C60. To the best of our knowledge, this is the first time that two fullerenes behaving as both electron donor (Lu3N@Ih‐C80) and acceptor (C60) are forming an electroactive dumbbell. DFT calculations reveal up to 16 diastereomeric pairs, that is, 8 with syn and 8 with anti orientation, with the anti‐RSSS isomer being the most stable. Spectroelectrochemical absorption and femtosecond transient absorption experiments support the notion that a C60??‐Lu3N@Ih‐C80?+ charge‐separated state is formed. Spin conversion from the charge‐separated singlet state C60??‐Lu3N@Ih‐C80?+ into the corresponding triplet state is facilitated by the heavy‐atom effect stemming from the Lu3N‐cluster, which, in turn, slows down the charge recombination by one order of magnitude. 相似文献
97.
The conjecture that when an additive hard-core mixture phase separates when one of the phases is spatially ordered, well supported by considerable evidence, is in contradiction with some simulations of a binary mixture of hard cubes on cubic lattices. By extending Rosenfeld's fundamental measure theory to lattice models we show that the phase behavior of this mixture is far more complex than simulations show, exhibiting regions of stability of several smectic, columnar, and solid phases, but no fluid-fluid demixing. A comparison with the simulations show that they are, in fact, compatible with a fluid-columnar demixing transition, thus bringing this model into the same demixing scheme as the rest of additive hard-core mixtures. 相似文献
98.
The strong law of large numbers for k-means and best possible nets of Banach valued random variables
Summary Let B be a uniformly convex Banach space, X a B-valued random variable and k a given positive integer number. A random sample of X is substituted by the set of k elements which minimizes a criterion. We found conditions to assure that this set converges a.s., as the sample size increases, to the set of k-elements which minimizes the same criterion for X. 相似文献
99.
We put forward a general procedure to obtain an approximate free-energy density functional for any hard-core lattice gas, regardless of the shape of the particles, the underlying lattice, or the dimension of the system. The procedure is conceptually very simple and recovers effortlessly previous results for some particular systems. Also, the obtained density functionals belong to the class of fundamental measure functionals and, therefore, are always consistent through dimensional reduction. We discuss possible extensions of this method to account for attractive lattice models. 相似文献
100.
Experimental Mechanics - The Hole-Drilling method is a semi-destructive technique useful for obtaining residual stress distributions by drilling and measuring relieved strains. The standard for... 相似文献