Due to the increasing influence of human engineering activities, it is important to monitor the transient disturbance during the evolution process of landslide. For this purpose, a high-performance piezoelectric sensor is presented in this paper. To adapt the high static and dynamic stress environment in slope engineering, two key techniques, namely, the self-structure pressure distribution method (SSPDM) and the capacitive circuit voltage distribution method (CCVDM) are employed in the design of the sensor. The SSPDM can greatly improve the compressive capacity and the CCVDM can quantitatively decrease the high direct response voltage. Then, the calibration experiments are conducted via the independently invented static and transient mechanism since the conventional testing machines cannot match the calibration requirements. The sensitivity coefficient is obtained and the results reveal that the sensor has the characteristics of high compressive capacity, stable sensitivities under different static preload levels and wide-range dynamic measuring linearity. Finally, to reduce the measuring error caused by charge leakage of the piezoelectric element, a low-frequency correction method is proposed and experimental verified. Therefore, with the satisfactory static and dynamic properties and the improving low-frequency measuring reliability, the sensor can complement dynamic monitoring capability of the existing landslide monitoring and forecasting system.

The present work is aimed at presenting the disturbance generated by a solar array drive assembly (SADA) driving a flexible system. Firstly, the vibration equation of SADA is obtained by simplifying and linearizing the electromagnetic torque. Secondly, the disturbance model of SADA driving a discrete flexible system is achieved based on the vibration equation established. Taking a two-dof flexible system as the study object, this disturbance model is simulated and analyzed. Lastly, a continuous flexible system, which is designed to simulate the solar array, is used to illustrate the simulation method of the disturbance emitted by SADA driving a continuous flexible system. All the achievements obtained from this project will provide a theoretical basis for the prediction of the disturbance emitted by the SADA driving solar array on the orbit.

Abstract-The micro-vibrations, generated by Solar Array Drive Assembly (SADA), of satellite can extensively alter and reduce its imaging quality as well as pointing direction precision. The present work aims to analyze the active and structural vibration disturbances of SADA driven in two different kinds of subdivision number (32 and 64) through theoretical analysis and experimentation. The considered drive mechanism is a two phase and four beat hybrid stepper motor. The formulations to calculate frequencies, forces and moments demonstrated by SADA, operating with various sub-division numbers, are derived leading to its comprehensive disturbance model. The developed mathematical expressions contain information related to period of input of electric pulse signal, solar array speed, number of rotor teeth, reduction ratio, amplitude coefficients, phase of disturbance force, beat number and sub-divisions. In order to validate the theoretical results, amplitude of disturbance forces and moments, produced by SADA driving no load / dead load, is acquired by using a rigid force / moment test platform. The obtained results verify that increase in sub-division number from 32 to 64 leads to reduction in disturbance force and moment generated by SADA, enhances its stability and smoothen the drive. The research work can find good deal of its applicability for drive circuit designing and vibration damping study of SADA.

Abstract. An efficient method, namely fixed interface mode synthesis-interval factor method (FIMS-IFM), is proposed to calculate the natural frequency of structure considering elastic joint with interval uncertainty. In this proposed method, the interval uncertain elastic joint is treated as spatial beam element with interval uncertain material parameters. Additionally, both the proposed method and Monte-Carlo simulation method are used to calculate the natural frequency of a specially designed structure with interval uncertain elastic joint. A meaningful conclusion can be acquired via comparing the calculation results of the two methods that, FIMS-IFM is correct and high-efficiency.

Original scientific paper PMTP (piezoelectric micro-vibrations test platform) is widely used to test the micro-vibrations emitted by the rotary equipment on a spacecraft. Due to the poor performance of the piezoelectric sensor in low frequency band, the test reliability of PMTP is low. A low-frequency compensation method is proposed to solve this problem. Firstly, the low-frequency compensation method of a single-axis piezoelectric force sensor is introduced and verified by experimental test. Secondly, the low-frequency compensation method of PMTP, which consists of eight single-axis piezoelectric force sensors, is proposed. Lastly, the low-frequency compensation method of PMTP is verified by experimental test. The results show that this method can effectively compensate the performance of PMTP in low frequency band. Keywords: low-frequency compensation; micro-vibrations; piezoelectric force sensor; piezoelectric micro-vibrations test platform Kompenzacija niske frekvencije probne platforme s piezoelektričnim mikro vibracijamaIzvorni znanstveni članak PMTP (probna platforma s piezoelektričnim mikro-vibracijama) općenito se rabi za ispitivanje mikro-vibracija koje ispušta rotirajuća oprema na svemirskoj letjelici. Zbog lošeg funkcioniranja piezoelektričnog senzora u zoni niskih frekvencija, pouzdanost ispitivanja PMTP je mala. Za rješenje tog problema predlaže se metoda kompenzacije niske frekvencije. Najprije se uvodi nisko frekvencijska metoda kompenzacije jednoosovinskog piezoelektričnog sensora snage i verificira eksperimentalnim ispitivanjem. Zatim se predlaže metoda kompenzacije niske frekvencije PMTP-a koja se sastoji od osam jednoosovinskih piezoelektričnih senzora snage. Na kraju se metoda kompenzacije niske frekvencije PMTP-a verificira eksperimentalnim ispitivanjem. Rezultati pokazuju da se tom metodom može učinkovito kompenzirati funkcioniranje PMTP-a u zoni niskih frekvencija.Ključne riječi: kompenzacije niske frekvencije; mikro-vibracije; probna platforma s piezoelektričnim mikro vibracijama; piezoelektrični senzor snage