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161.
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A new experimental technique has been developed to investigate the onset of fracture in metals at low and intermediate stress
triaxialities. The gage section of a flat specimen has been designed such that cracks are most likely to initiate within the
specimen center, remote from the specimen boundaries. Along with the specimen, a biaxial testing device has been built to
apply a well-defined displacement field to the specimen shoulders. The stress state within the specimen is adjusted by changing
the biaxial loading angle. Using this new experimental technique, the crack initiation in metals can be studied experimentally
for stress triaxialities ranging from 0.0 to 0.6. The stress and strain fields within the specimen gage section are determined
from finite element analysis. The reliability of the computational model of the test set-up has been verified by comparing
the simulation results with laser speckle-interferometric displacement measurements during testing. Sample experiments have
been performed on the Al-7Si-Mg gravity die casting alloy. A three-step hybrid experimental–numerical calibration procedure
has been proposed and applied to determine a phenomenological crack formation criterion for the Al-7Si-Mg alloy.
相似文献
D. MohrEmail: |
164.
《Arabian Journal of Chemistry》2019,12(5):718-728
A simple, rapid, precise, accurate and sensitive high performance liquid chromatographic method has been developed for simultaneous determination of ACE inhibitors with hydrochlorothiazide and indapamide in pharmaceutical formulations. ‘Design of Experiments’ (DoE) using ‘central composite design’ (CCD) was applied to facilitate method development and optimization. Mobile phase was optimized utilizing response surface methodology using Design Expert software. Chromatographic separation was achieved on Hypersil®-Gold C18 (100 × 4.6 mm, 3 μm, Thermo Fisher Scientific, USA), column at 25 °C. The mobile phase was 58% buffer (5 mM KH2PO4, containing triethylamine 0.25 ml/L), 25% acetonitrile and 17% methanol (pH adjusted to 2.8 ± 0.1). The analysis was performed at 215 nm. The mobile phase flow rate was 1.0 ml/min and injection volume 10 μl. The method was validated for linearity, limits of quantitation and detection, accuracy, precision, ruggedness and robustness as per the International Conference on Harmonization (ICH) guidelines. Calibration curves (for lisinopril, hydrochlorothiazide, captopril, imidapril, perindopril, indapamide and trandolapril) were linear in the concentration range of 5–35 μg/ml. The limit of detection and limit of quantitation for experimental drugs ranged from 0.03 to 0.61 and 0.08–1.84 μg/ml respectively. 相似文献
165.
Pump−probe experiments at the TEMPO beamline using the low‐α operation mode of Synchrotron SOLEIL 下载免费PDF全文
Mathieu G. Silly Tom Ferté Marie Agnes Tordeux Debora Pierucci Nathan Beaulieu Christian Chauvet Federico Pressacco Fausto Sirotti Horia Popescu Victor Lopez-Flores Marina Tortarolo Maurizio Sacchi Nicolas Jaouen Philippe Hollander Jean Paul Ricaud Nicolas Bergeard Christine Boeglin Bharati Tudu Renaud Delaunay Jan Luning Gregory Malinowski Michel Hehn Cédric Baumier Franck Fortuna Damjan Krizmancic Luigi Stebel Rudi Sergo Giuseppe Cautero 《Journal of synchrotron radiation》2017,24(4):886-897
The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump–probe experiments. Among others, the low‐α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50 ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low‐α mode of the experimental set‐ups developed at the TEMPO beamline to perform pump–probe experiments with soft X‐rays based on photoelectron or photon detection are presented. A 282 kHz repetition‐rate femtosecond laser is synchronized with the synchrotron radiation time structure to induce fast electronic and/or magnetic excitations. Detection is performed using a two‐dimensional space resolution plus time resolution detector based on microchannel plates equipped with a delay line. Results of time‐resolved photoelectron spectroscopy, circular dichroism and magnetic scattering experiments are reported, and their respective advantages and limitations in the framework of high‐time‐resolution pump–probe experiments compared and discussed. 相似文献
166.
利用常见化学仪器滴瓶设计系列化学实验——钠与乙醇反应、铝与NaOH溶液反应、铜与浓、稀硝酸反应以及铁的析氢腐蚀和吸氧腐蚀等, 改进后的实验装置简约, 便于携带, 易于操作, 现象明显, 无污染, 也为教学赢得时间。 相似文献
167.
C. Berbecaru H.V. Alexandru A. Popescu G. Socol F. Sima Ion Mihailescu 《Applied Surface Science》2009,255(10):5476-5479
Pulsed laser deposition (PLD) method was used to obtain bioglass (BG) thin film coatings on titanium substrates. An UV excimer laser KrF* (λ = 248 nm, τ = 25 ns) was used for the multi-pulse irradiation of the BG targets with 57 or 61 wt.% SiO2 content (and Na2O-K2O-CaO-MgO-P2O5 oxides). The depositions were performed in oxygen atmosphere at 13 Pa and for substrates temperature of 400 °C. The PLD films displayed typical BG of 2-5 μm particulates nucleated on the film surface or embedded in. The PLD films stoichiometry was found to be the same as the targets. XRD spectra have shown, the glass coatings obtained, had an amorphous structure. One set of samples, deposited in the same conditions, were dipped in simulated body fluids (SBFs) and subsequently extracted one by one after several time intervals 1, 3, 7, 14 and 21 days. After washing in deionized water and drying, the surface morphology of the samples and theirs composition were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), IR spectroscopy (FTIR) and energy dispersive X-ray analysis (EDX). After 3-7 days the Si content substantially decreases in the coatings and PO43− maxima start to increase in FTIR spectra. The XRD spectra also confirm this evolution. After 14-21 days the XRD peaks show a crystallized fraction of the carbonated hydroxyapatite (HAP). The SEM micrographs show also significant changes of the films surface morphology. The coalescence of the BG droplets can be seen. The dissolution and growth processes could be assigned to the ionic exchange between BG and SBFs. 相似文献
168.
The well-known refinement of the Nash Equilibrium (NE) called an Evolutionarily Stable Strategy (ESS) is investigated in the quantum Prisoner's Dilemma (PD) game that is played using an Einstein-Podolsky-Rosen type setting. Earlier results report that in this scheme the classical NE remains intact as the unique solution of the quantum PD game. In contrast, we show here that interestingly in this scheme a non-classical solution for the ESS emerges for the quantum PD. 相似文献
169.
170.
Q. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):387-392
The effects of the non-rotating wave approximation (non-RWA) on the
spontaneous emission of a V-type three-level atom are studied, where the
excited states are coupled to a common ground state by a weak laser field
and the upper-level doublet is driven by a strong microwave field. When the
non-RWA is applied to the interaction of the atom with the microwave field,
for some values of the parameters involved, the spontaneous emission
spectrum is comprised of a central peak and a series of sidebands with a
constant spacing of the microwave frequency, and the central peak and/or
sidebands can be split into two components. The physical interpretation of
the spectral characteristics is given in light of the dressed states. 相似文献