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排序方式: 共有296条查询结果,搜索用时 15 毫秒
91.
Huseyin Sehitoglu Ibrahim Karaman X. Zhang Hong Kim Yuriy Chumlyakov I. Kireeva Hans J. Maier 《Metallurgical and Materials Transactions A》2001,32(3):477-489
Single-crystal orientations of NiTi10Cu alloys were studied under incremental, cyclic compression conditions to establish
the pseudoelastic and shape memory response of this class of alloys. This material exhibits a two-step transformation involving
cubic to orthorhombic martensite (B2 → B19) followed by orthorhombic to monoclinic martensite (B19 → B19′). The transformation
parameters (shear magnitudes and directions for habit and twin planes) were determined associated with the B2 → B19 transformation.
The growth of monoclinic martensite correspondent variant pairs (CVPs) emanating from the orthorhombic structure was also
analyzed. The transformation strain for the B2 → B19 case was orientation dependent and lower than the B19 → B19′ transformation
in compression for all orientations except those near the [001] pole. The experimental results show that the critical transformation
stress is orientation dependent and is in the range 30 to 58 MPa. Orientations that exhibit lower transformation stress (or
high resolved shear stress factors, [100] and [012]) produce higher recoverable strains (as high as 4 pct), while other orientations
([011], [111], and [123]) with lower resolved shear stress factors result in recoverable strains less than 3 pct. At higher
strains, inelastic deformation develops, limiting recoverability. The recoverable strains are lower than the theoretical values
for two main reasons: the transformation is curtailed first by austenite slip and subsequently by martensite slip, and the
orthorhombic structure does not fully transform to the monoclinic martensite. 相似文献
92.
93.
Yuriy V. Tokovyy Chien-Ching Ma 《International Journal of Pressure Vessels and Piping》2011,88(5-7):248-255
This paper presents an analytical method for solving the axisymmetric stress problem for a long hollow cylinder subjected to locally-distributed residual (incompatible) strains. This method is based on direct integration of the equilibrium and compatibility equations, which thereby have been reduced to the set of two governing equations for two key functions with corresponding boundary and integral conditions. The governing equations were solved by making use of the Fourier integral transformation. Application of the method is illustrated with an analysis of the welding residual stresses in a butt-welded thick-walled pipe. 相似文献
94.
95.
Shunyi Zhao Yuriy S. Shmaliy Guoli Ji Sanowar H. Khan 《International Journal of Adaptive Control and Signal Processing》2017,31(7):1061-1076
This paper combines the finite impulse response filtering with the Kalman structure (predictor/corrector) and proposes a fast iterative bias‐constrained optimal finite impulse response filtering algorithm for linear discrete time‐invariant models. In order to provide filtering without any requirement of the initial state, the property of unbiasedness is employed. We first derive the optimal finite impulse response filter constrained by unbiasedness in the batch form and then find its fast iterative form for finite‐horizon and full‐horizon computations. The corresponding mean square error is also given in the batch and iterative forms. Extensive simulations are provided to investigate the trade‐off with the Kalman filter. We show that the proposed algorithm has much higher immunity against errors in the noise covariances and better robustness against temporary model uncertainties. The full‐horizon filter operates almost as fast as the Kalman filter, and its estimate converges with time to the Kalman estimate. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
96.
Formation and properties of sediments in constructed wetlands for treatment of domestic wastewater 总被引:1,自引:0,他引:1
Yuriy Vergeles Nataliya Butenko Andriy Ishchenko Felix Stolberg Marika Hogland 《Urban Water Journal》2016,13(3):293-301
Sediments formation and biogeochemical properties were studied in an experimental constructed wetland site in Ukraine (“Bioplato”) for treatment of domestic effluents. The wetland, with a capacity of 50 m3 d? 1 of wastewater, consists of vertical and horizontal filtrations units with fine gravel, middle and coarse sand, a subsurface flow unit with natural wetland soil applied, and a septic tank and sludge-drying field. Macrophytes, reed (Phragmites australis), cattail (Typha latifolia) and a number of sedge species (Carex spp.) were planted in the area and dominate the average cover of 85–90%. Treatment efficiency for BOD5 and suspended solids was 93–96%, for COD – 82%, for nutrients – 27–50%, and for pathogenic microorganisms 99.3–99.6%. Sludge was sampled at each unit followed by standard laboratory analyses of its main characteristics: total organic carbon (TOC), total nutrients (N, P), contents of trace elements, abundance of pathogenic microorganisms, and general toxicity. Results confirmed that the top layer of sludge from each unit of wetland could be used as a source of fertilizers for grain and leguminous crops. 相似文献
97.
Ignition of aluminum-rich Al-Ti mechanical alloys in air 总被引:1,自引:0,他引:1
Yuriy L. Shoshin 《Combustion and Flame》2006,144(4):688-697
Ignition of metastable Al-Ti mechanical alloys with titanium concentrations from 10 to 25 at% was investigated experimentally. A thin layer of powder was coated on an electrically heated filament. The ignition instant was identified from the powder's radiation measured in real time. Simultaneously, filament temperatures were measured using a high-speed infrared pyrometer to determine the ignition temperature. The experiments were conducted at different filament heating rates in the range of 3×103-2×104 K/s to determine the ignition kinetics. The ignition temperatures and kinetics were compared to the respective characteristics of the phase changes and oxidation steps observed for the same mechanical alloys using thermal analysis. It was shown that at the heating rates exceeding 103 K/s, the exothermic formation of a metastable L12 phase of Al3Ti occurring during heating of the Al-Ti mechanical alloys triggers their ignition. This conclusion was confirmed by additional ignition experiments in which annealed mechanical alloys already containing this transition Al3Ti phase did not ignite in the same temperature range as fresh mechanical alloys. The ignition kinetics identified for Al-Ti mechanical alloys based on thermal analysis and on ignition experiments enables one to predict ignition temperatures as a function of both composition and heating rate. Specifically, extrapolation is possible to higher heating rates typical for aerosol flames. 相似文献
98.
Georgiy B. Shul’pin Marina V. Kirillova Yuriy N. Kozlov Lidia S. Shul’pina Alexander R. Kudinov Armando J.L. Pombeiro 《Journal of Catalysis》2011,277(2):164-172
Decamethylosmocene, (Me5C5)2Os (1), is a pre-catalyst in a very efficient oxidation of alkanes with hydrogen peroxide in acetonitrile at 20–60 °C. The reaction proceeds with a substantial lag period that can be reduced by the addition of pyridine in a small concentration. The lag period can be removed if 1 is incubated with pyridine and/or H2O2 in MeCN prior to the alkane oxidation. Alkanes, RH, are oxidized primarily to the corresponding alkyl hydroperoxides, ROOH. Turnover numbers attain 51,000 in the case of cyclohexane (maximum turnover frequency was 6000 h?1) and 3600 in the case of ethane. The oxidation of benzene and styrene also occurs with a lag period to afford phenol and benzaldehyde, respectively. A kinetic study of cyclohexane oxidation and selectivity parameters (measured in the oxidation of n-heptane, methylcyclohexane, isooctane, cis- and trans-dimethylcyclohexanes) indicates that the oxidation of saturated, olefinic, and aromatic hydrocarbons proceeds with the participation of hydroxyl radicals. The 1/H2O2/py/MeCN system also oxidizes 1-phenylethanol to acetophenone. 相似文献
99.
Yuriy Suhak Katarzyna Izdebska Paweł Skupiński Aleksandra Wierzbicka Anna Reszka Piotr Sybilski Bogdan J. Kowalski Andrzej Mycielski Zbigniew R. Zytkiewicz Michał Soszko Andrzej Suchocki 《Materials Chemistry and Physics》2014
This paper presents experimental results of implementation of ZnO single crystals as photoanodes in photoelectrochemical (PEC) cells for hydrogen generation through the process of water splitting. Both, as-grown and O2-annealed ZnO single crystals were investigated for this purpose. A 351 nm argon laser line was used as the light source. The XRD investigations showed that used ZnO crystals are of good crystalline quality. It was found that the as-grown ZnO single crystals possess higher conversion efficiencies comparing to the O2-annealed one. The photocurrent density was found to increase significantly with the increase of external bias applied and excitation light intensity. Time dependent photocurrent density characteristics showed that the decay of photocurrent density was not observed within the measurement time. The differences in behaviour of the as-grown and the annealed in O2 ZnO single crystals are discussed in terms of crystals intrinsic defects. 相似文献
100.