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排序方式: 共有266条查询结果,搜索用时 15 毫秒
1.
Influence of geosynthetic reinforcement on the load-settlement characteristics of two-layer subgrade
The possibility of realistic prediction of two-layer subgrade load-settlement characteristics is discussed. The case of improvement of the soft subgrade properties using the geosynthetic reinforcement placed at the boundary between two different subgrade layers is analysed. In the first part of the paper, a short review of the main conclusions from experimental results dealing with the influence of geosynthetic reinforcement on the load-settlement characteristics of subgrade is presented. Then, the results of using the selected analytical membrane-action model to describe the reinforcement action in soil are discussed. The model is verified on the basis of data obtained from previously published laboratory tests. Particular attention is devoted to influencing some basic initial parameters on the accuracy of obtained results. Important problems which need intensive investigations are identified. 相似文献
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3.
Microstructure and Mechanical Properties of the Ductile Al–Ti–Mo–Nb–V Refractory High Entropy Alloys
Cieślak Grzegorz Dąbrowa Juliusz Jawańska Monika Parzuchowska Agnieszka Oleszak Dariusz 《Metallurgical and Materials Transactions A》2022,53(2):653-662
Metallurgical and Materials Transactions A - A number of non-equimolar refractory high entropy alloys (RF HEAs) from the Al–Ti–Mo–Nb–V system are synthesized, with the... 相似文献
4.
The reaction between copper and a mixture of SO2+O2 was studied at 973 and 1073 K. The experimental methods included optical microscopy, X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray analysis, and radiotracer. It is concluded that the inward transport of oxidants through the scale as well as oxygen and sulfur dioxide liberation in the reactions taking place at phase boundaries suggest that secondary processes occur inside the oxide-sulphate layer. Therefore, Cu2O and CuOCuSO4 appear inside this layer. In the metal-consumption zone, a Cu2O layer forms, which contains small amounts of a sulfide phase near the metal-scale interface. 相似文献
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W. Kuznik M.G. BrikI. Cie?lik A. MajchrowskiL. Jaroszewicz N.S. AlZayedA.M. El-Naggar I. SildosS. Lange V. KiiskI.V. Kityk 《Journal of Alloys and Compounds》2012,511(1):221-225
We present a complex fluorescence study of a series of gadolinium oxide polycrystalline powders singly, doubly and triply doped with trivalent rare earth ions (Er3+, Tb3+, and Dy3+), to explore a possibility of their use as materials for white light emitting diodes. The excitation and luminescence spectra along with the decay kinetics were measured in the temperature range from 6 to 300 K. The luminescence efficiency was studied within the visible spectral range, i.e. −400 nm to 750 nm under excitation by 355 nm third harmonic Nd:YAG laser pulses. Singly doped Er3+ sample gave stronger luminescence signals, but others showed significantly larger decay lifetimes. The successive rare earths doping leads to substantial changes of the spectral positions due to the up-conversion processes. In the singly (Er3+) doped sample, following the time resolved spectrum and decay curves, there are two different types of emissions: at 660 nm and at shorter wavelengths (below 640 nm) the red emission's lifetime is ten times longer than at shorter wavelengths. The singly doped sample shows unclear temperature-dependence of luminescence with lifetime at 550 nm (the longest at 100 K, similarly at 6 K and 300 K) and achieved luminous efficacy 73.5 lm/W. 相似文献
7.
X-ray fluorescence (XRF) is a commonly used analytical method to quantify lead (Pb), a toxic element, in atmospheric aerosol. The commercially available reference materials used for calibrating XRF do not mimic the concentrations and filter materials of particulate matter (PM) monitoring networks. In this study, we described an aerosol deposition method to generate Pb reference materials (RMs) over a range of concentrations to serve several purposes for the US Environmental Protection Agency (EPA) and Interagency Monitoring of PROtected Visual Environments (IMPROVE) monitoring networks including laboratory auditing, federal equivalency method evaluation, and calibration and quality control of XRF instruments. The RMs were generated using a laboratory-built aerosol chamber equipped with a federal reference sampler at concentration levels ranging from 0.0125 to 0.70 μg/m3. XRF analysis at UC Davis was demonstrated to be equivalent to a US and EU reference method, inductively coupled plasma—mass spectrometry (ICP-MS), for measuring Pb on RMs following a methodology described in the United States and international standards. The Pb concentrations on subsets of the RMs were verified by three other XRF laboratories with different analyzers and/or quantification methods and were shown to be equivalent to the UC Davis XRF analysis. The generated RMs were demonstrated to have short and long-term stability, satisfying an additional requirement of reference materials.
Copyright © 2016 American Association for Aerosol Research 相似文献
8.
Krystyna Bogdanowicz-Szwed Andrzej Policht 《Advanced Synthesis \u0026amp; Catalysis》1984,326(5):721-728
The reaction of enamines 1 derivatives of cyclohexanon- or cycloheptanon-2-carboxylic acid anilides with malononitrile gave in the first step 2-phenylcarbamoyl-cycloalkylideno-malononitriles 3 , which in turn were converted into 1-oxo-2-phenyl-3-amino-4-cyano-cycloalkenoisoquinolines 4 . Enamines containing an adjacent diphenylamidino group 6 reacted with malononitrile giving 1-phenylimino-2-phenyl-3-amino-4-cyano-cycloalkenoisoquinolines 7 . The alkaline hydrolysis of 7 yielded 1-phenylamino-3-oxo-4-cyano-cycloalkenoisoquinoline 8 . 相似文献
9.
The small angle X-ray scattering (SAXS) was used to examine structural changes of starches after γ-irradiation with 10, 20, 30 kGy doses. The diminution of intensity of small-angle reflexion relating to 100 A spacing indicates destruction of long-range ordering in granules after γ-irradiation. It was observed as well in the case of irradiation of dry pure starches as a starch contained in potatoes. The method suggests possibility of quick identification of irradiated foodstuffs. 相似文献
10.
Iwona Cieślik 《Acta Informatica》2005,42(1):1-20
The problem of on-line coloring of an arbitrary graphs is known to be hard. Here we consider the problem of on-line coloring
in the simplified situation where the input graph is KKs,t-free. We show that the on-line coloring algorithm with the First Fit strategy of proposed by Capponi and Pilotto in [1] is the best one for KK1,t-free graphs (t≥3). A.Capponi and C.Pilotto have shown that this algorithm achieves a competitive ratio of t−1 while we show that it is the best possible. However for the family of KKs,t-free graphs (s≥2, t≥2) there exists no on-line coloring algorithm with a competitive function. The problem of an on-line cliques covering for
these families is hard. There exists no on-line cliques covering algorithm with a competitive function for the family of KKs,t-free graphs (s≥ 1, t≥3). The additional assumption that the input graph is given in a connected way does not help a lot and does not change our
results described above. 相似文献