This study investigates the diffusion and mechanical properties of Ti-Al-V-Cr alloys to facilitate high-strength titanium alloys design. In this study, ten solid/solid diffusion couples were prepared using body-center...
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This study investigates the diffusion and mechanical properties of Ti-Al-V-Cr alloys to facilitate high-strength titanium alloys design. In this study, ten solid/solid diffusion couples were prepared using body-centered cubic (BCC) Ti-Al-V alloys and annealed at 1373 K and 1473 K for 8 hours. The atomic mobility parameters for the Ti-Al and Al-V binary systems were re-optimized, the diffusion coefficients of the Ti-Al-V system were calculated, and an atomic mobility database for the Ti-Al-V system was established. Six sets of quaternary solid/ solid diffusion couples were annealed at 1373 K for 7 hours. A comprehensive atomic mobility database for the Ti-Al-V-Cr system was developed using the CALculation of PHAse Diagrams (CALPHAD) method. numerical inverse determination of diffusion coefficients for BCC Ti-Al-V-Cr alloys at 1373 K. Nanoindentation and Electron probe microanalysis (EPMA) measurements were employed to systematically investigate the variation of Young's modulus, hardness, and elastic recovery as functions of alloy composition along the diffusion interfaces. Consequently, a composition-dependent mechanical property database for Ti-rich Ti-Al-V-Cr alloys was developed. Additionally, wear resistance and hot service parameter of the alloys were evaluated. Among the studied compositions, the Ti-5Al-0.5V-11.1Cr (TAVC) alloy exhibited superior hardness-to-Young's modulus ratios (H/E and H3/E2), excellent wear resistance, and favorable hot service parameters. These findings provide valuable insights into the design and optimization of Ti-Al-V-Cr alloys for high-strength applications, elucidating the intricate relationships between alloy composition and mechanical performance.
In general, relative permeability data can be obtained from laboratory coreflooding experiments. Such experimental data can be interpreted analytically or numerically. Compared to analytical methods, when the numerica...
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In general, relative permeability data can be obtained from laboratory coreflooding experiments. Such experimental data can be interpreted analytically or numerically. Compared to analytical methods, when the numerical inversion methods are applied to interpret the coreflooding experimental data, the reservoir performance obtained prior to and after breakthrough can be utilized comprehensively, the capillary effects and the heterogeneity of core samples can also be taken into account, so the estimated result is not only accurate but also complete. Moreover, the numerical inversion methods can be applied to large-scale reservoirs. This article introduces systematically the methodology of numerical inversion methods, and then reviews the present research status. Finally, several proposals of implicitly estimating relative permeability data are put forward from aspects of optimization algorithms' properties, estimation of endpoint saturations and treatment scale by automatic history matching. (C) 2011 Published by Elsevier Ltd.
In general, relative permeability data can be obtained from laboratory coreflooding experiments. Such experimental data can be interpreted analytically or numerically. Compared to analytical methods, when the numerica...
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In general, relative permeability data can be obtained from laboratory coreflooding experiments. Such experimental data can be interpreted analytically or numerically. Compared to analytical methods, when the numerical inversion methods are applied to interpret the coreflooding experimental data, the reservoir performance obtained prior to and after breakthrough can be utilized comprehensively, the capillary effects and the heterogeneity of core samples can also be taken into account, so the estimated result is not only accurate but also complete. Moreover, the numerical inversion methods can be applied to large-scale reservoirs. This article introduces systematically the methodology of numerical inversion methods, and then reviews the present research status. Finally, several proposals of implicitly estimating relative permeability data are put forward from aspects of optimization algorithms’ properties, estimation of endpoint saturations and treatment scale by automatic history matching.
Laplace transforms in two variables are useful in the solution of partial differential equations. However, their analytic inverses are often difficult to obtain. In this paper, the numericalmethod based on evaluating...
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Laplace transforms in two variables are useful in the solution of partial differential equations. However, their analytic inverses are often difficult to obtain. In this paper, the numericalmethod based on evaluating the Bromwich integral and using the computation algorithm of fast Fourier transform (FFT) is extended to the inversion of two-dimensional (2-D) Laplace transforms. A new inversion formula is devised so that the values of the inverted 2-variable function on the rectangle grids can be efficiently obtained via multiple sets of 2-D fast Hartley transform (FHT) computations. The proposed FHT-based inversion algorithm is thus suitable for the computation in a multiprocessor environment. (C) 1999 The Franklin Institute. Published by Elsevier Science Ltd. All rights reserved.
In-situ spectroscopic ellipsometry is known to be very sensitive, non-invasive technique for monitoring and control of thin film growth. In the production of optical interference coatings the refractive index of the m...
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In-situ spectroscopic ellipsometry is known to be very sensitive, non-invasive technique for monitoring and control of thin film growth. In the production of optical interference coatings the refractive index of the material is usually assumed to remain constant within a single layer. Under such assumption only the optical thickness of the layer can be efficiently controlled. For modern complex structures, however, even insignificant deviation from the design, due to the shift in the refractive index, can be very detrimental to the resulting performance of the coating. Simultaneous real-time determination of refractive index and growth rate is necessary in order to comply with strict specifications. If the index departs from the target value, one has to adjust process parameters and, ultimately, perform re-calculation of the filter structure to compensate for an error. We will review the work performed in our laboratory during last few years. Development of several different control strategies will be discussed and their application to the control of PECVD of optical interference coatings demonstrated. Latest work is concerned with the advances in the closed-loop control of the fabrication of optical thin films by in-situ multi-wavelength phase-modulated kinetic ellipsometry using both, direct numericalinversion algorithm for the real-time reconstruction of refractive index and layer thickness and real-time least-squire fitting-based approach. These techniques have been tested on quarter-wave index optical filters as well as on inhomogeneous refractive index profiles and demonstrated efficiency and robustness.
This paper proposes a latent variable approach to examine the induced innovation hypothesis originating from Hicks (The theory of wages, Macmillan, London, 1932). It allows a flexible decomposition of total factor pro...
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This paper proposes a latent variable approach to examine the induced innovation hypothesis originating from Hicks (The theory of wages, Macmillan, London, 1932). It allows a flexible decomposition of total factor productivity into Type I (exogenous) and Type II (induced) technical changes using a latent variable d as an argument in a variable cost function. By making extensive use of duality theory, we are able to estimate the Hicksian input demand functions, which are explicit in d but may lack a closed-form representation in terms of observable variables such as input prices and output level. The "unobservability " of d is solved by using a numericalinversion estimation method. We apply this methodology with an appropriate estimator to investigate the impact of induced innovation on China's total factor productivity growth. Our findings indicate that the induced innovation hypothesis is strongly supported by the data and that induced innovation has a positive and profound effect on China's productivity growth.
The mathematical model was established for multiple-layer cylindrical walls in order to determine the temperature profile according to the fundamental law of heat conduction. The iteration of the Laplace transformatio...
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The mathematical model was established for multiple-layer cylindrical walls in order to determine the temperature profile according to the fundamental law of heat conduction. The iteration of the Laplace transformation and the Stehfest numerical inversion method were used for Laplace transformation. The temperature profile was obtained. The multiple-layer cylinder apparatus was designed. The measurement results in laboratory and oil field show that the method has high precision. The solution method is also used under different initial and boundary conditions with different heat source systems.
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