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101.
Effects of Cone Angles on Nonlinear Vibration Responses of Functionally Graded Shells北大核心CSCD 下载免费PDF全文
The nonlinear vibration responses of functionally graded materials (FGMs) shells with different cone angles under external loads were studied. Firstly, the Voigt model was employed to describe the physical properties along the thickness direction of FGMs conical shells. Then, the motion equations were derived based on the 1st-order shear deformation theory, the von Kármán geometric nonlinearity and Hamilton’s principle. Next, the Galerkin method was applied to discretize the motion equations and the governing equations were simplified into a 1DOF nonlinear vibration differential equation under Volmir’s assumption. Finally, the nonlinear motion equations were solved with the harmonic balance method and the Runge-Kutta method, and the amplitude frequency response characteristic curves of the FGMs conical shells were obtained. The effects of different material distribution functions and different ceramic volume fraction exponents on the amplitude frequency response curves of conical shells were discussed. The bifurcation diagrams of conical shells with different cone angles, as well as time process diagrams and phase diagrams for different excitation amplitudes, were described. The motion characteristics were characterized by Poincaré maps. The results show that, the FGMs conical shells present the nonlinear characteristics of hardening springs. The chaotic motions of the FGMs conical shells are restrained and not prone to motion instability with the increase of the cone angle. The FGMs conical shell present a process from the periodic motion to the multi-periodic motion and then to chaos with the increase of the excitation amplitude. © 2022 Editorial Office of Applied Mathematics and Mechanics. All rights reserved. 相似文献
102.
研究了一类具有非线性源项和粘性项的拟线性抛物型方程组的初边值问题.通过构造稳定集, 证明了此问题整体解的存在性, 并建立了解的长时间行为.同时在放松函数的适当假设条件下, 得到了初始能量非负时解的爆破性质及解的生命区间估计. 相似文献
103.
In this paper, a tumor immune model with time delay is studied. First, the stability of nonnegative equilibria is analyzed. Then the time delay τ is selected as a bifurcation parameter and the existence of Hopf bifurcation is proved. Finally, by using the canonical method and the central manifold theory, the criteria for judging the direction and stability of Hopf bifurcation are given. 相似文献
104.
Shengrui Lin Yiting Cai Jiaxi Luo Ziyu Xuan Yicong Zhao 《Journal of Nonlinear Modeling and Analysis》2022,4(2):220-244
In this paper, we investigate the Novikov equation with weak dissipation terms. First, we give the local well-posedness and the blow-up scenario. Then, we discuss the global existence of the solutions under certain conditions. After that, on condition that the compactly supported initial data keeps its sign, we prove the infinite propagation speed of our solutions, and establish the large time behavior. Finally, we also elaborate the persistence property of our solutions in weighted Sobolev space. 相似文献
105.
The local optimality conditions to polynomial optimization problems are a set of polynomial equations (plus some inequality conditions). With the recent techniques of Gröbner bases one can find all solutions to such systems, and hence also find global optima. We give a short survey of these methods. We also apply them to a set of problems termed with exact solutions unknown in the problem sets of Hock and Schittkowski. To these problems we give exact solutions. 相似文献
106.
有阻尼Sine-Gordon方程的全局吸引子的维数 总被引:2,自引:0,他引:2
本文通过引入新范数,得到有阻尼Sine-Gordon方程的Dirichlet问题的全局吸引子的维数的一个估计.结果表明:当“阻尼”与“扩散”同时增大或正弦项系数减小时,吸引子的维数减小.特别地,得到了零维吸引子存在的参数条件. 相似文献
107.
LetM be a compact minimal surface inS
3. Y. J. Hsu[5] proved that if S222, thenM is either the equatorial sphere or the Clifford torus, whereS is the square of the length of the second fundamental form ofM, ·2 denotes theL
2-norm onM. In this paper, we generalize Hsu's result to any compact surfaces inS
3 with constant mean curvature.Supported by NSFH. 相似文献
108.
A. A. Goldstein 《Mathematical Programming》1993,62(1-3):223-237
This paper modifies the convergence conditions of a back-tracking global Newton method announced in Goldstein (1991), making them sharper and easier to apply. A new version of the Kantorovich inequalities is presented that is simple to state and prove. An application is made to the centering problem for polytopes. Based on an idea of Ye (1989), an algorithm is given for the feasibility problem of linear inequalities.This paper is dedicated to Phil Wolfe on the occasion of his 65th birthday. 相似文献
109.
Global optimization and stochastic differential equations 总被引:5,自引:0,他引:5
F. Aluffi-Pentini V. Parisi F. Zirilli 《Journal of Optimization Theory and Applications》1985,47(1):1-16
Let
n
be then-dimensional real Euclidean space,x=(x
1,x
2, ...,x
n)T
n
, and letf:
n
R be a real-valued function. We consider the problem of finding the global minimizers off. A new method to compute numerically the global minimizers by following the paths of a system of stochastic differential equations is proposed. This method is motivated by quantum mechanics. Some numerical experience on a set of test problems is presented. The method compares favorably with other existing methods for global optimization.This research has been supported by the European Research Office of the US Army under Contract No. DAJA-37-81-C-0740.The third author gratefully acknowledges Prof. A. Rinnooy Kan for bringing to his attention Ref. 4. 相似文献
110.
Establishing a reliable method to predict the global mean temperature (Te) is of great importance because CO2 reduction activities require political and global cooperation and significant financial resources. The current climate models all seem to predict that the earth's temperature will continue to increase, mainly based on the assumption that CO2 emissions cannot be lowered significantly in the foreseeable future. Given the earth's multifactor climate system, attributing atmospheric CO2 as the only cause for the observed temperature anomaly is most likely an oversimplification; the presence of water (H2O) in the atmosphere should at least be considered. As such, Te is determined by atmospheric water content controlled by solar activity, along with anthropogenic CO2 activities. It is possible that the anthropogenic CO2 activities can be reduced in the future. Based on temperature measurements and thermodynamic data, a new model for predicting Te has been developed. Using this model, past, current, and future CO2 and H2O data can be analyzed and the associated Te calculated. This new, esoteric approach is more accurate than various other models, but has not been reported in the open literature. According to this model, by 2050, Te may increase to 15.5 ℃ under "business-as-usual" emissions. By applying a reasonable green technology activity scenario, Te may be reduced to approximately 14.2 ℃. To achieve CO2 reductions, the scenario described herein predicts a CO2 reduction potential of 513 gigatons in 30 years. This proposed scenario includes various CO2 reduction activities, carbon capturing technology, mineralization, and bio-char production; the most important CO2 reductions by 2050 are expected to be achieved mainly in the electricity, agriculture, and transportation sectors. Other more aggressive and plausible drawdown scenarios have been analyzed as well, yielding CO2 reduction potentials of 1051 and 1747 gigatons, respectively, in 30 years, but they may reduce global food production. It is emphasized that the causes and predictions of the global warming trend should be regarded as open scientific questions because several details concerning the physical processes associated with global warming remain uncertain. For example, the role of solar activities coupled with Milankovitch cycles are not yet fully understood. In addition, other factors, such as ocean CO2 uptake and volcanic activity, may not be negligible. 相似文献