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A Complex Conjugate (CC) control is implemented with a Proportional-Derivative (PD) controller for WEC devices to improve and optimize power absorbed. Traditionally, CC control has not been realizable due to actual implementation that requires acceleration feedback or exact term cancellation. For the PD implementation, only the stiffness term is employed to modify the impedance and achieve resonance...
In this paper, the effect of the acting electrode position on the dynamic behavior of a polysilicon microcantilever is investigated by considering different oscillating modes. The oscillation of structures in higher bending modes is used to increase the quality factor and to decrease the loss of energy during oscillation. The tests are performed in ambient conditions as well as in vacuum. The position...
We report a unique MEMS resonant force sensor design that provides both reduced motional resistance and greatly enhanced strain gauge factor to target operation under ambient conditions. The proposed device has been realized in an Aluminum Nitride (AlN) on Silicon (Si) process, where the piezoelectric-AlN transducers are uniquely decoupled from a force sensitive triple beam tuning fork (TBTF) resonator...
The approximation methods to investigate the dynamical processes in the strong nonlinear single-or multi-degree physical systems are studied in the paper. The developed procedure of the investigation of the oscillations in the nonlinear systems with the concentrated mass can solve not only the analysis problems but the problems of the cyberphysical oscillation system synthesis on the projective phase...
Piezoelectric ultrasonic motors (PUMs) are based on the concept of driving the runner by a mechanical vibration excited on the stator via the converse piezoelectric effect. They exhibit merits of small size, simple structure, quick response, high accuracy and resolution, self-locking when power off and a lack of electromagnetic radiation. The linear PUMs become the research focus in recent years as...
A U-shaped linear piezoelectric ultrasonic motor (PUM) was proposed, designed and tested in this work, in which three longitudinal transducers were used together to achieve the linear driving by two feet synchronously. Longitudinal vibrations of the transducers were generated with certain temporal shift to form the desired elliptical movements on the two driving feet. Finite element method (FEM) was...
The behavior of vibrating crystal plates under the action of external forces was studied. The plates were respectively subjected to diametrical compression force and bending force in different configurations: (a) a clamped cantilever, (b) a cantilever with displaced knife edges, and (c) a dual support mounting with displaced knife edge applied midway between. Finite element models were developed using...
Microbubbles (MBs) are widely used in clinical site as contrast agents in ultrasound imaging due to its eminent responsiveness to several MHz band. In recent years, ultrasound drug delivery system (DDS) using MBs are widely researched to achieve selective medication to the targeted diseased part. In the condition of high number density of bubbles to enhance the performance of DDS, it is essentially...
Microbubbles (MBs) are widely used in clinical site as contrast agents in ultrasound imaging due to its eminent responsiveness to several MHz band ultrasound. In recent years, ultrasound drug delivery system (DDS) using MBs are widely researched to achieve selective medication to the targeted diseased part. In the condition of high number density of bubbles to enhance the performance of DDS, it is...
A micromechanical silicon resonant accelerometer (MSRA) is a potential micro accelerometer with high accuracy. One of the most important factors affecting its performance is temperature. To research the effect of temperature on micromechanical silicon resonant accelerometer, this study based on the original micromechanical silicon resonant accelerometer, designs a chip-level temperature-sensitive...
In this paper, through researching principles for the bonded PZT drive and analyzing the second class of piezoelectric force - electric couple, a model along the length of PZT-driven model to the mechanical vibration was established based on continuum dynamics. The interaction between the PZT and the structure of the bonding layer was the key factor during investigation. Followed by construction of...
A microwave atomic clock based on 113Cd+ ions at Tsinghua University is carried out for seven years. To further improve the performance of the clock, a new experimental setup with dual traps and dual species ions was proposed. To investigate the efficiency of sympathetic cooling and the dynamic process of ions, numerical simulation study of the dual-species ion ensembles by the Molecular-dynamics...
We report highly tunable nanoelectromechanical systems NEMS shallow arches under dc excitation voltages. Silicon based in-plane doubly clamped bridges, slightly curved as shallow arches, are fabricated using standard electron beam lithography and surface nanomachining of a highly conductive device layer on a silicon-on-insulator wafer. By designing the structures to have gap to thickness ratio of...
This paper presents an easy-to-use and efficient implementation of the added mass method for calibrating various atomic force microscope (AFM) probes without damage to the probe, which is based on the added mass method. The method is achieved by using a pneumatic control system and a home-made glass micro-pipette. Compared with the conventional added mass method, this method achieves the operation...
The need for wireless sensor networks that can run for long times without the need of battery replacement has risen the need for energy harvesters. Industrial environments have plenty of energy sources that can be harvested; pressure fluctuations are a high energy density source that can be harvested using piezoelectric devices. Present devices have introduced flat metallic plates as the main force...
This paper presents a focus on harvesting energy from mechanical sources operating at 20Hz or below. For many practical energy harvesting applications, low frequency mechanical sources present an issue for efficient energy conversion. Often energy harvesters become inefficient when driven outside of a narrow band about their natural frequency, which may be orders of magnitude above the frequency of...
The multimodal control of a 2D controlled-Friction Device is presented. We use the Vector control method because the phase and amplitude of two vibration modes at a same frequency can be precisely set. The closed loop response time of 10 ms is achieved. The device is then associated with a finger position sensor. The algorithm of the multimodal approach is then tested. In spite of the inevitable limitations...
Piezoelectric energy harvesting has received great attention over the last 20 years. The main goal of this work is to discuss the potential advantages of introducing non-linearities in the dynamics of a beam type piezoelectric vibration energy harvester. The described device is essentially a cantilever beam partially covered by piezoelectric material with a force electromagnetically applied to the...
In small mobile robots, decreasing the number of actuators is usually desirable to reduce the size and weight of the robot, but it is usually at the expense of the robot's degree of freedom (DOF). This work presents the development and preliminary experimental testing of a novel Legged Piezoelectric Miniature Robot (LPMR) driven only by a single piezoelectric unimorph actuator and yet fully capable...
For static and dynamic measurement of one component force was invented a force sensor based on flexible structure MEMS [1] as well as information sensing method for this sensor, based on high-frequency absorption effect [2]. Very important and difficult part of force sensor design is RF field radiator. This article deals with design and simulation of this radiator features. To ensure the reliability...
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