Modeling and analysis of piezoelectric beam with periodically variable cross-sections for vibration energy harvesting

A bimorph piezoelectric beam with periodically variable cross-sections is used for the vibration energy harvesting. The effects of two geometrical parameters on the first band gap of this periodic beam are investigated by the generalized differential quadrature rule （GDQR） method. The GDQR method is also used to calculate the forced vibration response of the beam and voltage of each piezoelectric layer when the beam is subject to a sinusoidal base excitation. Results obtained from the analytical method are compared with those obtained from the finite element simulation with ANSYS, and good agreement is found. The voltage output of this periodic beam over its first band gap is calculated and compared with the voltage output of the uniform piezoelectric beam. It is concluded that this periodic beam has three advantages over the uniform piezoelectric beam, i.e., generating more voltage outputs over a wide frequency range, absorbing vibration, and being less weight.

Differential quadrature time element method for structural dynamics

An accurate and efficient differential quadrature time element method （DQTEM） is proposed for solving ordi- nary differential equations （ODEs）, the numerical dissipation and dispersion of DQTEM is much smaller than that of the direct integration method of single/multi steps. Two methods of imposing initial conditions are given, which avoids the tediousness when derivative initial conditions are imposed, and the numerical comparisons indicate that the first method, in which the analog equations of initial displacements and velocities are used to directly replace the differential quadra- ture （DQ） analog equations of ODEs at the first and the last sampling points, respectively, is much more accurate than the second method, in which the DQ analog equations of initial conditions are used to directly replace the DQ analog equations of ODEs at the first two sampling points. On the contrary to the conventional step-by-step direct integration schemes, the solutions at all sampling points can be obtained simultaneously by DQTEM, and generally, one differential quadrature time element may be enough for the whole time domain. Extensive numerical comparisons validate the effi- ciency and accuracy of the proposed method.

Rule of Chinese Medicine Syndrome Differentiation in the Patients with Thoracic Diseases at Perioperation Stage

Objective： To study the rule of syndrome differentiation in the patients with thoracic diseases at perioperation stage. Methods： A standard was created referring to the related literature, and it was applied to differentiate the Chinese medicine syndrome in 150 patients before and three days after thoracic operation. Results： Before operation, Chinese medicine syndromes were as differentiated as phlegm type in 45.3%, blood stasis type in 17.3%, and qi-stagnancy type in 16.0%. The patients with asthenia syndrome markedly increased after operation, accounting for 34.0% （51 patients, including qi-, yin-, and blood-deficiency syndromes）. The most frequently seen intermixed syndromes were qi-deficiency with phlegm-stasis syndrome and Pi （脾）-deficiency with phlegm-dampness syndrome. The intermixed syndromes revealed in 37.5% and 42.0% of the patients before and after operation, respectively. Conclusion： The syndrome in the patients with thoracic disease before operation was mostly the excessive syndrome, mainly the phlegm syndrome type; at postoperation stage, Chinese medicine syndrome in patients become asthenia in essence with excessive superficiality, which is mostly revealed as Pi-deficiency with phlegm-dampness.

Advances in terrestrial system research in China

Land surface is of spatial-temporal heterogeneity. Terrestrial system（TS） comprehensively studies on land surface and physical regionalization objectively describes geographical zonation of the system. China has a vast area with apparent spatial variations in resources and environmental conditions, which highly influence on socio-economic development. In this paper, progress of the TS studies in China is overviewed and research priorities in the near future are prospected. Since the 1950 s, China has paid great attention to the TS study as its socio-economic development, and conducted research on physical geographical regionalization, eco-geographical regionalization and comprehensive regionalization. Along with the deepening of global change research, dynamics of TS have been highly concerned. During the studies, methodology has been developed from qualitative research of integration of experts＇ brainpower gradually to quantitative research based on field observation and experiments of the natural processes, including physical, chemical and biological processes, as well as application of information technology and mathematical simulation. In the near future, TS would combine with the ideology, objectives and key researches of Future Earth program, to focus on the mechanism and regional effects of interaction among land surface elements, the response of TS to global change, the quantitative recognition on regional unit boundary, and the application to TS in sustainable socio-economic development.

Modular design of adaptive robust controller for strict-feedback stochastic nonlinear systems

A modular approach of the estimation-based design in adaptive linear control systems has been extended to the adaptive robust control of strict-feedback stochastic nonlinear systems with additive standard Wiener noises and constant unknown parameters.By using Itô’s differentiation rule,nonlinear damping and adaptive Backstepping procedure,the input-to-state stable controller of global stabilization in probability is developed,which guarantees that system states are bounded and the system has a robust stabilization.According to Swapping technique,we develop two filters and convert dynamic parametric models into static ones to which the gradient update law is designed.Transient performance of the system is estimated by the norm of error.Results of simulation show the effectiveness of the control algorithms.The modular design,which has a concise hierarchy,is more flexible and versatile than a Lyapunov-based algorithm.

Electron Raman scattering in a cylindrical quantum dot

Electron Raman scattering（ERS） is investigated in a CdS cylindrical quantum dot（QD）.The differential cross section is calculated as a function of the scattering frequency and the size of the QD.Single parabolic conduction and valence bands are assumed,and singularities in the spectrum are found and interpreted.The selection rules for the processes are also studied.The ERS studied here can be used to provide direct information about the electron band structure of these systems.