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The design and implementation of an adaptive disturbance rejection approach is presented for single-input-single-output linear-time-invariant uncertain mechanical systems subject to sinusoidal disturbances with unknown amplitudes and frequencies. The proposed technique suggests construction of a set of stabilizing tuning functions via a state estimate observer in a backstepping fashion to achieve asymptotic disturbance rejection. The tuning functions design is based on a single Lyapunov function incorporating both the error states and update law, and hence, global stability and improved transient performance are readily achieved. Utilizing only the system output, a virtual control input is used in place of non-measurable and unknown signals. The performance of the adaptation algorithm is demonstrated through both simulations and experiments for a single-degree-of-freedom system with unknown parameters and subject to an unknown sinusoidal disturbance. Significant matching between the simulation and experimental results is observed. [DOI: 10.1115/1.1538624]

A procedure in designing optimal Dynamic Vibration Absorbers (DVA) for a structurally damped beam system subjected to an arbitrary distributed harmonic force excitation, is presented. The Timoshenko beam theory is used to assess the effects of rotatory inertia and shear deformation. The method provides flexibility of choosing the number of absorbers depending upon the number of significant modes which are to be suppressed. Uniform cross-sectional area is considered for the beam and each absorber is modeled as a spring-mass-damper system. For each absorber with a selected mass, the optimum stiffness and damping coefficients are determined in order to minimize the beam dynamic response at the resonant frequencies for which they are operated. For this purpose, absorbers each tuned to a different resonance, are used to suppress any arbitrarily number of resonances of the beam. The interaction between absorbers is also accounted for in the analysis. The optimum tuning and damping ratios of the absorbers, each tuned to the mode of concern, are determined numerically by solving a min-max problem. The Direct Updated Method is used in optimization procedure and the results show that the optimum values of the absorber parameters depend upon various factors, namely: the position of the applied force, the location where the absorbers are attached, the position at which the beam response should be minimized, and also the beam characteristics such as boundary conditions, rotatory inertia, shear deformation, structural damping, and cross sectional geometry. Through the given examples, the feasibility of using proposed study is demonstrated to minimize the beam dynamic response over a broad frequency range. The resulting curves giving the non-dimensional absorber parameters can be used for practical applications, and some interesting conclusions can be drown from the study of them.

Extraction from the herbs was performed using the Soxhlet method. Various formula was synthesized for niosomes containing the extracts through thin film synthesis technique, and the most efficient formulation was selected. Afterwards, physicochemical properties of niosomes, including size, polydispersity index (PDI), zeta potential, morphology, encapsulation efficacy (EE%), extract release rate, non-interactive action between the extracts and niosomes, antibacterial potential, and cellular uptake were assessed. Finally, the toxicity level of the niosomes to breast cancer cells was compared and their impact on the expression of p53 and MCL-1 was evaluated. Our data demonstrated that the synthesized niosomes were sensitive to the temperature and pH. Also, the niosomes containing Hedera Helix extract (Nio-HHE) sized 97.7 nm, with a zeta potential of −19.9 ± 6.7 mV, PDI of 0.35, and 58 ± 2.4% encapsulation efficacy showed more toxicity to the cancer cells than the niosomes of Glycyrrhiza glabra extract (Nio-GGE) with the size of 111 ± 8.5 nm, zeta potential of −23.5 ± 4.5 mV, PDI of 0.113, and 69 ± 1.2% encapsulation efficacy. The former system proved to have more antibacterial potential, and affect the expression of the oncogenes more than the latter. Meanwhile, both niosomal systems demonstrated an acceptable cellular uptake, and no chemical interaction with the extracts was observed. Furthermore, useful function of the synthesized niosomes was confirmed by morphological assessments. Our data confirmed that encapsulation of herbal extracts improves their anticancer and antibacterial potential. We concluded that Nio-HHE has more significant antitumor effects on breast cancer cells than Nio-GGE. Consequently, applying nano drug delivery systems based on herbal therapy could mitigate the side effects resulting from chemotherapy and radiotherapy, and offer promising perspectives for treatment of breast cancer.

06-1668 Esmaeili, M., M. Durali, and N. Jalili. Ring microgyroscope modeling and performance evaluation. Journal of Vibration and Control (United Kingdom) 12(5):537-553, May 2006 (www.sagepublications.com). KEYWORDS: Coriolis forces, excitation, Galerkin [...]

06-1426 Ramaratnam, A., and N. Jalili. A switched stiffness approach for structural vibration control theory and real-time implementation. Journal of Sound and Vibration (United Kingdom) 291(1,2):258-274, March 21, 2006 (www.idealibrary.com). [...]