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41.
薛儒英 《浙江大学学报(理学版)》1993,20(2):133-140
本文讨论了有界区域上带临界指数的非线性椭圆型方程混合边值问题二对非平凡解的存在性,给出了存在二对非平凡解的条件. 相似文献
42.
黄瓜幼苗胚轴的不同部位对离子体子叶培养物器官分化的影响是不同的,热击处理具不同长度胚轴的黄瓜幼苗,其子叶培养物的直接花芽分化率不同,其中以单去根处理的为最高,去根+去/2胚轴的为最低,对照和去根+去3/4胚轴的居中,结果提示胚轴中存在着与成花有关的促进和/或抑制因子,热击无根苗产生了分子量约为67-94kD的热激蛋白,热击处理还使中性区域蛋白质含量下降。 相似文献
43.
用前馈多层神经网络方法研究了高聚物的热力学性质.在本文的人工神经网络模型中,输入层为高聚物的密度ρ,缠结分子量M-e,玻璃化转变温度T-g,高聚物的高弹性模量G-N,钩状构像含量β和无扰均方末端距的特征比C-∞;输出层为高聚物比热C-p;隐含层的节点数为5.最后预测结果与实验结果非常接近,相对误差为2.2~5.4,这为研究高聚物的其它物理性质提供了一种新的方法. 相似文献
44.
We further develop the lattice Boltzmann (LB) model [Physica A 382 (2007) 502] for compressible flows from two aspects. Firstly, we modify the Bhatnagar--Gross-Krook (BGK) collision term in the LB equation, which makes the model suitable for simulating flows with different Prandtl numbers. Secondly, the flux limiter finite difference (FLFD) scheme is employed to calculate the convection term of the LB equation, which makes the unphysical oscillations at
discontinuities be effectively suppressed and the numerical dissipations be significantly diminished. The proposed model is validated by recovering results of some well-known benchmarks, including (i) The thermal Couette flow; (ii) One- and two-dimensional Riemann problems. Good agreements are obtained
between LB results and the exact ones or previously reported solutions. The flexibility, together with the high accuracy of the new model, endows the proposed model considerable potential for tracking some long-standing problems and for investigating nonlinear nonequilibrium complex systems. 相似文献
45.
N. G. Fytas A. Malakis 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):39-43
The three-dimensional bimodal random-field Ising model is studied
via a new finite temperature numerical approach. The methods of
Wang-Landau sampling and broad histogram are implemented in a
unified algorithm by using the N-fold version of the Wang-Landau
algorithm. The simulations are performed in dominant energy
subspaces, determined by the recently developed critical minimum
energy subspace technique. The random-fields are obtained from a
bimodal distribution, that is we consider the discrete
(±Δ) case and the model is studied on cubic lattices with
sizes 4≤L ≤20. In order to extract information for the
relevant probability distributions of the specific heat and
susceptibility peaks, large samples of random-field realizations
are generated. The general aspects of the model's scaling behavior
are discussed and the process of averaging finite-size anomalies
in random systems is re-examined under the prism of the lack of
self-averaging of the specific heat and susceptibility of the
model. 相似文献
46.
圆管层流脉冲流动对流换热数值分析 总被引:3,自引:0,他引:3
对等热流和等壁温边界条件下圆管内层流脉冲流动对流换热问题进行了数值模拟。在等热流边界条件下的数值计算结果与理论解吻合很好。计算结果表明:在等热流和等壁温边界下脉冲流动可引起速度、温度以及努塞尔数随时间波动,振幅越大,脉冲频率越小,波动越大。但它们的时均值均等于在相同雷诺数下稳态流动的值,脉冲流动不能强化换热。 相似文献
47.
48.
49.
A three-dimensional mathematical model is developed to examine the flow of nonlinear thermal radiation Oldroyd-B nanofluid past a bidirectional linearly stretched surface in a porous medium. The flow is induced by temperature dependent thermal conductivity, chemical reaction and convective heat and mass conditions. Novel characteristics of Brownian motion and thermophoresis are accompanied by magnetohydrodynamic and heat generation/absorption. Self-similar transformations are employed to convert the system of nonlinear partial differential equations to a system of ordinary differential equations with high nonlinearity and are solved by strong analytic technique named as Homotopy Analysis method (HAM). Effects of varied arising parameters on involved distributions are reflected through graphical illustrations. From this study, it is perceived that strong magnetic field hinders the fluid's motion and leads to rise in temperature that eventually lowers heat transfer rate from the surface. Further, decrease in heat transfer rate is also observed for enhanced values of thermal radiation parameter. To validate our results, a comparison with already published paper in limiting case is also given and results are found in excellent oncurrence; hence reliable results are being presented. 相似文献
50.
LIU Bin LIANG Ying FENG Shi-Ping CHEN Wei-Yeu 《理论物理通讯》2006,46(1):171-174
Within the t-J model, the heat transport of electron-doped cobaltates is studied based on the fermionspin theory. It is shown that the temperature-dependent thermal conductivity is characterized by the low-temperature peak located at a finite temperature. The thermal conductivity increases monotonously with increasing temperature at low-temperatures T 〈 0.1 J, and then decreases with increasing temperature for higher temperatures T 〉 0.1 J, in qualitative agreement with experimental result observed from NaxCoO2. 相似文献