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171.
The study of the local stability of the equilibrium of an elastic body subjected to conservative and gyroscopic forces, which was initiated in [6] is extended. Two variational principles are established in actual and equivalent energy terms respectively. These principles, together with the stability criterion formulated in [6], form a generalized version of (and reduce to) the classical energy principles governing the stability of conservative non-gyroscopic systems, and are applied to the example of a loaded (or unloaded) elastic shaft under constant rotation. In addition, a necessary and sufficient condition for the applied forces to be gyroscopic or conservative is obtained explicitly as a function of the change in force components due to a small disturbance superimposed on the equilibrium state. 相似文献
172.
Chaos synchronization using fuzzy logic controller 总被引:1,自引:0,他引:1
The design of a rule-based controller for a class of master-slave chaos synchronization is presented in this paper. In traditional fuzzy logic control (FLC) design, it takes a long time to obtain the membership functions and rule base by trial-and-error tuning. To cope with this problem, we directly construct the fuzzy rules subject to a common Lyapunov function such that the master–slave chaos systems satisfy stability in the Lyapunov sense. Unlike conventional approaches, the resulting control law has less maximum magnitude of the instantaneous control command and it can reduce the actuator saturation phenomenon in real physic system. Two examples of Duffing–Holmes system and Lorenz system are presented to illustrate the effectiveness of the proposed controller. 相似文献
173.
Chuan-Kuei Huang Hsiau-Hsian Nien Shih-Kuen Changchien Hong-Wei Shieh 《Optics Communications》2007,280(2):300-310
This paper presents a novel scheme for implementation of quasi-optimal chaotic random codes (CRC). Usually, the localization grey relational grade (LGRG) approaches 1 by using less random codes to encrypt digital color images. On the contrary, randomized codes cause highly independent images. In this paper, the LGRG between original and encoded image is used as the quality characteristic, and the chaotic system’s initial values x0, y0 and z0 which influence the quality characteristic are chosen as control factors and the levels are also decided. According to the control factors and levels, this paper applied a Taguchi orthogonal array for the experiments, and generated a factor response graph, to figure out a set of chaotic initial values. Finally, the quasi-optimal CRC are decided by these initial values. Eventually, the most effective encryption of digital color images can be obtained by applying the quasi-optimal CRC. The experimental results have demonstrated that the proposed scheme is feasible and efficient. 相似文献
174.
Mohammad Ababneh Juan-Gonzalo Barajas-Ramírez Guanrong Chen Leang S. Shieh 《Chaos, solitons, and fractals》2007,31(5):1149-1164
In this paper, a new and systematic method for designing robust digital controllers for uncertain nonlinear systems with structured uncertainties is presented. In the proposed method, a controller is designed in terms of the optimal linear model representation of the nominal system around each operating point of the trajectory, while the uncertainties are decomposed such that the uncertain nonlinear system can be rewritten as a set of local linear models with disturbed inputs. Applying conventional robust control techniques, continuous-time robust controllers are first designed to eliminate the effects of the uncertainties on the underlying system. Then, a robust digital controller is obtained as the result of a digital redesign of the designed continuous-time robust controller using the state-matching technique. The effectiveness of the proposed controller design method is illustrated through some numerical examples on complex nonlinear systems––chaotic systems. 相似文献
175.
Jason Sheng-Hong Tsai Chih-Cheng Huang Shu-Mei Guo Leang-San Shieh 《Applied Mathematical Modelling》2011,35(8):3893-3904
The analytic continuous to discrete model conversion for the system with a singular system matrix based on the computationally fast and numerically stable sign function is firstly presented in this note. The proposed methodology yields a more accurate model conversion than existing approximate methods. An illustrative example is presented to show the accuracy of the proposed methodology. 相似文献
176.
Wen‐Lung Kuo Yu‐Ling Huang Chien‐Chang Shen Bor‐Jinn Shieh Chien‐Chih Chen 《中国化学会会志》2007,54(5):1359-1362
Chemical investigation on the rhizoma of Liparis nakaharai resulted in the isolation of a new phenanthrene, 7‐hydroxy‐2,3,4‐trimethoxyphenanthrene ( 1 ), and three new prenylated benzoic acids, liparacids A ( 2 ), B ( 3 ), and C ( 4 ), together with four known compounds, moscatin, nudol, batatasin III, and 2,5‐dihydroxy‐4‐methoxy‐9,10‐dihydrophenanthrene. The structures of these compounds were elucidated by spectroscopic analysis. 相似文献
177.
The purpose of this communication has been to show the application of MCD to dimerization of benzoic acid and its derivatives. We present results of the dimerization equilibrium constants from resolving the observed MCD spectra of the intramolecular charge transfer band (CT) into the spectra of monomers and dimers, and of the B-coefficients (or the magnetic rotational strengths) of the CT band of MCD of monomers and dimers. 相似文献
178.
Yan Yi Du Jason S.H. Tsai Harshal Patil Leang S. Shieh Yuhua Chen 《Applied Mathematical Modelling》2011
In this paper, an indirect identification scheme is proposed for identifying the parameters of the continuous-time first-order plus time delay (FOPTD) model and the second-order plus time delay (SOPTD) model from step responses. Unlike the existing direct identification scheme, which identifies the parameters of the continuous-time FOPTD and SOPTD models directly from the continuous-time step response data, the proposed indirect scheme is to pre-identify discrete-time FOPTD and SOPTD models from the discretized continuous-time step response input–output data, then convert the obtained discrete-time models to the desirable continuous-time models. The proposed method is then extended to identify the afore-mentioned models from the step responses of the systems contaminated with input noise and constant output disturbance. The proposed simple alternative method exhibits good estimation performances in both the time domain and the frequency domain. Illustrative examples are presented to demonstrate the effectiveness of the proposed scheme. 相似文献
179.
Partial inverse nodal problems for Sturm–Liouville operators on a compact equilateral star graph are investigated in this paper. Uniqueness theorems from partial twin‐dense nodal subsets in interior subintervals or arbitrary interior subintervals having the central vertex are proved. In particular, we posed and solved a new type partial inverse nodal problems for the Sturm–Liouville operator on the compact equilateral star graph. 相似文献