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61.
A new approximate analytical approach for accurate higher-order nonlinear solutions of oscillations with large amplitude is
presented in this paper. The oscillatory system is subjected to a non-rational restoring force. This approach is built upon
linearization of the governing dynamic equation associated with the method of harmonic balance. Unlike the classical harmonic
balance method, simple linear algebraic equations instead of nonlinear algebraic equations are obtained upon linearization
prior to harmonic balancing. This approach also explores large parameter regions beyond the classical perturbation methods
which in principle are confined to problems with small parameters. It has significant contribution as there exist many nonlinear
problems without small parameters. Through some examples in this paper, we establish the general approximate analytical formulas
for the exact period and periodic solution which are valid for small as well as large amplitudes of oscillation. 相似文献
62.
The stability and control characteristics of two twin-lift helicopter configurations are analyzed in this paper. In order to address the issue of configuration selection from a handling qualities viewpoint, their open-and closed-loop characteristics are compared. The two twin-lift configurations considered are the twin-lift with spreader bar and twin-lift without spreader bar. The nonlinear models describing the dynamics of these two configurations in the lateral/vertical plane are derived. The open-loop characteristics of the two systems are compared by linearizing the nonlinear models about a symmetric hovering equilibrium condition. The closed-loop characteristics of the two systems are compared using nonlinear controllers based on feedback linearization schemes. The performance of the resulting closed-loop systems in carrying out a typical twin-lift mission is evaluated through nonlinear simulation. Also, the effects of helicopter performance degradation and measurement errors on the overall system performance are discussed.[B] Matrix multiplying the control vector in the nonlinear model[B1] Matrix multiplying the control vector in the linear model[C] Matrix defining vector of variables to be controlled[C1] Damping matrixCijElement of the damping matrix
e Parameter used in the linear model = M
1
h
1/I
1=M
2
h
2/I
2,/ft{f} Vector independent of controls in the nonlinear model
g Acceleration due to gravity, ft/sec2
h1, h2Distance of tether attachment point to the center of gravity for helicopters 1 and 2, ft
h Parameter used in the linear model, =h
1=h
2, ft
h Distance between rotor hub and the helicopter center of gravity, ft
h h/l
H Distance of the load from the spreader bar c.g., ftH1, H2Length of tethers 1 and 2, ftIRMass moment of inertia of spreader bar, slug-ft2
I1, I2Roll moments of inertia of helicopters 1 and 2, slug-ft2
k Non-dimensional hub control moment coefficientKDDerivative gainsKIIntegral gainsKPProportional gains[Ki] Stiffness matrixKijElement of the stiffness matrix
l Parameter used in the linear model, =H
1=H
2, ft
L Spreader bar length, ftNomenclature 相似文献
63.
This study is devoted to analysis of semi-implicit compact finite difference (SICFD) methods for the nonlinear Schrödinger equation (NLS) perturbed by the wave operator (NLSW) with a perturbation strength described by a dimensionless parameter ε∈(0,1]. Uniform l∞-norm error bounds of the proposed SICFD schemes are built to give immediate insight on point-wise error occurring as time increases, and the explicit dependence of the mesh size and time step on the parameter ε is also figured out. In the small ε regime, highly oscillations arise in time with O(ε2)-wavelength. This highly oscillatory nature in time as well as the difficulty raised by the compact FD discretization make establishing the l∞-norm error bounds uniformly in ε of the SICFD methods for NLSW to be a very interesting and challenging issue. The uniform l∞-norm error bounds in ε are proved to be of O(h4+τ) and O(h4+τ2/3) with time step τ and mesh size h for well-prepared and ill-prepared initial data. Finally, numerical results are reported to verify the error estimates and show the sharpness of the convergence rates in the respectively parameter regimes. 相似文献
64.
65.
利用重合度理论和不等式分析技巧,获得了一类具有偏差变元的高阶中立型Lienard方程(x(t)-cx(t-δ))~((m))+f(x(t))x′(t)+β(t)g(x(t-T(t)))=p(t)周期解存在性的新充分条件,推广和改进了已有文献的相关结论. 相似文献
66.
考虑下列具多偏差变元的四阶p-Laplace方程:[φp(u″(t))]″+f(u(t))u′(t)+g(t,u(t-τ1(t)),u(t-τ2(t)),…,u(t-τn(t)))=e(t).利用重合度定理得出其周期解的存在性结论. 相似文献
67.
具有偏差变元的双曲型微分方程组解的振动性 总被引:65,自引:0,他引:65
本文获得了双曲型方程组在齐次Neumann,Dirichlet和Robin边值条件下,所有解振动的充分条件. 相似文献
68.
69.
基于辩论的多agent商务谈判辩论产生和决策过程研究 总被引:1,自引:0,他引:1
由于在自动谈判中加入辩论成分能够允许Agent在谈判过程中通过辩论的形式交换和交流额外的信息,进而影响对方的信念、偏好、意向或目标,使谈判向着有利于达成协议方向发展,并提高谈判效率,降低交易成本,因此已经成为多Agent商务谈判领域的热点发展方向.本文针对如何产生辩论这一重要问题进行研究,提出了"候选辩论集的产生策略"和"基于冲突分析的辩论目标产生模型",分析了基于辩论的多Agent商务谈判决策过程,并通过原型系统进行了验证.本文的研究成果将促使多Agent商务谈判系统向着更为实用方向发展. 相似文献
70.
J. Tervo M. Vauhkonen P. J. Vauhkonen J. P. Kaipio 《Mathematical Methods in the Applied Sciences》2000,23(4):357-377
This paper deals with the dynamics of non‐linear distributed parameter fixed‐bed bioreactors. The model consists of a pair of non‐linear partial differential (evolution) equations. The true spatially three‐dimensional situation is considered instead of the usual one‐dimensional approximation. This enables one to take into account the effects of flow profiles and the true location of the measurement transducer. The (output) evolution of the corresponding open‐loop control system is simulated. Furthermore, the associated closed‐loop system with respect to the relevant output function is considered. Especially, the asymptotic output tracking is found to be successful by applying the usual process based on the state feedback linearization. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献