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This essay presents the design method of applying ultrasonic levitation bearing to high-speed motor and using single supporting rotor of ultrasonic levitation high-speed motor. It adopts piezoelectric transducer, the permanent magnet synchronous motor spindle; the radiation surface of transducer and the levitation support cap of the spindle adopt the conical structure with the same taper. It ensures that the spindle is highly automatic centering when it rotates at the high speed. The test results show that the spindle runs smoothly without having contact friction noise and problems of torque fluctuation and radial vibration caused by the electromagnetic coupling, when the output power of the ultrasonic power supply is at 500w, the speed of the spindle is over 20000rpm, and the levitation clearance is more than 100nm, which is more than the sum of roughness Ra for two contact surfaces.

As the fatigue life of a piezoelectric actuator is relative to the service life of a piezoelectric pump,this paper carries out a fatigue life-related research.First,times of stress cycle corresponding to the ultimate stress is experimentally acquired when Pb(Zr,Ti)O3(PZT-5)ceramics suffers from the fatigue failure under an electro-mechanical coupling field.The number of samples selected at different levels of stress in the above experiment are discriminated and corrected by using the coefficient of variation.After data processing,a p-S-N double logarithm curve and its linear regression equation are obtained with the safety life at different levels of stress under conditions of 95% degree of confidence and 99.9% livability calculated respectively,which offers important and necessary data for the fatigue life calculation of piezoelectric actuator.Finally,the fatigue life of the piezoelectric actuator of a certain resonance-type air pump is calculated to be 4461 h with safety factor 1.25 by using ansys and hypothesis of fatigue damage accumulation.These results perfect the technical parameters of this air pump and the fatigue data,and the calculation method can be applied to the fatigue calculation of PZT-5 actuator in other kinds of piezoelectric pumps.

AIM To evaluate the differential diagnostic potential of lesion stiffness assessed by the sonoelastographic strain index ratio (SR) and elastographic color scoring system (UE) for breast lesions. MATERIALS AND METHODS Three hundred and forty two breast masses (158 benign and 184 malignant) from 325 consecutive patients (mean age 44.2 years; range 16-81)who had been scheduled for a sonographically guided core biopsy were examined with grey scale sonography,doppler sonography and sonoelastography. Each lesion was classified with ACR's BI-RADS assessment category (2, 3 and 4A=Benign and; 4B, 4C, 5=Malignant) and the 5-point scoring system proposed by Itoh et al, with scoring 1-3=benign and 4-5=malignant. Strain and area ratios of each lesion were calculated within the same machine. Histological diagnosis was used as the reference standard. The area under the curve (AUC) and cut-off point were obtained by receiver operating curve and the cross table Fischer Test was carried out for assessing diagnostic value. Sensitivity, specificity, PPV, NPV, accuracy and false-discovery rates were compared. RESULTS The mean strain ratios for benign and malignant lesions were 1.87 and 7.9 respectively. (P

On the basis of principles of vibrating piezoelectric vibrators to syntonize the connected diaphragms,a piezoelectric resonant air pump with a magnetic spring was proposed to improve the driving ability of the piezoelectric pump for gas moving.First,the working principle of the piezoelectric resonant air pump with magnetic spring was analysed,a dynamic model of the pump resonance was established and the main factors effecting the membrane amplitude were obtained.Then,a prototype was designed and the resonance frequency of the system and the displacement magnification of the piezoelectric vibrator were measured by an impedance analyzer and a photovoltaic displacement sensor,respectively.Finally,a testing facility to measure the volume and output pressure of the resonance pump was developed and the effects of the axial distance of magnetic spring on the output volume and pressure were analyzed.Experimental results indicate that the amplification factor is 4.5 when the sinusoidal AC driving voltage,resonant frequency and the magnetic force of the axial spacing of the magnetic spring are 200 V,133 Hz and 9 mm,respectively.Moreover,the maximum flow rate is 524 ml/min and the maximum pressure is 9.2 kPa.Results demonstrate that the gas transportation capacity has been improved by using the proposed piezoelectric resonant air pump.

To get fatigue properties of the small and hard brittle components working at conditions of little amplitudes and high frequency forces,this paper presents a novel kind of resonance and high frequency fatigue testing machine driven by a piezoelectric vibrator(PZT、PLZT or PMN).First,the working principle of the piezoelectric resonance and high frequency fatigue testing machine was introduced,and the dynamic model of the machine was established and its systemic dynamic characteristics were obtained.Then,a prototype was designed and produced.Finally,the dynamic load on the specimen was measured by the prototype.The results indicate that the dynamic load on the specimen is 24.7-99.2 N by changing the AC voltage amplitude(100-250 V) and the thickness of the plate spring(1.1-0.6 mm).The prototype designed in this paper is suitable for the tensile and bending fatigue testing under conditions of little amplitudes and high frequency forces with the dynamic load mentioned above.

A Piezo-hydraulic Energy Harvester(PHEH) was presented based on solid-fluid coupling vibration to harvest low-frequency and high-level vibration energy,and its structure as well as working principle were introduced.With an established energy-conversion model,the influence factors on the piezo-hydraulic harvester were analyzed.The theoretic results show that the output performance of the PHEH depends on the vibration frequency/level,the structure and size of piezodisc/cylinder,liquid volume/performance,and system backpressure.The desired performance can not be achieved unless the above parameters are matched well.By a piezodisc with a diameter of 60 mm and a thickness of 0.9 mm and a cylinder with a diameter of 16 cm and a length of 100 cm,a PHVI was fabricated and tested by taking water as liquid medium at different frequencies/backpressures/exciter-amplitudes.The test results suggest that there is an optimal vibration frequency(8 Hz) for the PHEH to achieve the maximal output voltage,which rises with the increasing of backpressure and vibration level.In the case of unvaried other parameters,the achieved voltage from the PHEH under 0.4 MPa is 1.65 times that under 0.2 MPa.

A new type of piezoelectric electro-hydraulic servo valve system was proposed. And then multilayer piezoelectric actuator based on new piezoelectric ceramic material was used as the electricity-machine converter of the proposed piezoelectric electro-hydraulic servo valve. The proposed piezoelectric electro-hydraulic servo valve has ascendant performance compared with conventional ones. But the system is of high nonlinearity and uncertainty, it cannot achieve favorable control performance by conventional control method. To develop an efficient way to control piezoelectric electro-hydraulic servo valve system, a high-precise fuzzy control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts: a feedforward loop with Preisach hysteresis nonlinear model and a feedback loop with high-precise fuzzy control. Experimental results show that the hysteresis loop and the maximum output hysteresis by the PID control method are 4.22% and 2.11 μm, respectively; the hysteresis loop and the maximum output hysteresis by the proposed control method respectively are 0.74% and 0.37 μm, respectively; the maximum tracking error by the PID control method for sine wave reference signal is about 5.02%, the maximum tracking error by the proposed control method for sine wave reference signal is about 0.85%.

A novel piezoelectric (PZT) precision step rotary actuator was developed on the basis of PZT technology. It adopts the principle of bionics and works with an inside anchoring/loosening of the stator and a distortion structure of the uniformly distributed thin flexible hinge to solve problems such as ineffective anchoring/loosening, low step rotary frequency, small travel, poor resolution, low speed and unsteady output. The developed actuator is characterized by high frequency (30 Hz), high speed (380 μrad/s), large travel (>270°), high resolution (1 μrad/step), and work stability. It greatly improves the ability to drive the existing PZT step rotary actuator. The new actuator can be applied in the field of micromanipulation and precision engineering, including precision driving and positioning and optics engineering.

A piezoelectric actuated prestage driver of hydraulic servo valves for the low-frequency response of electrohydraulic servo valve electromagnetic prestage driver was presented. The new driver was driven by piezoelectric multilayer actuators. The displacement of a piezoelectric multilayer actuator was amplified by a flexure-hinged amplifier based on the principles of triangle amplification. Static and dynamic characteristics were tested on the model machine. The characteristics of good linearity, high resolution, and high-frequency response were approved. The natural frequency reached 1.201–kHz using finite element analysis, and the practice measurement result was 1–kHz.

With a micropump, the release rate of drug delivery is able to be controlled easily to maintain the therapeutic efficacy. A high-performance piezoelectric cantilever-valve micropump was investigated for this purpose. The effect of valves on the output performance of the PZT micropump was analyzed at first. With taking into account the influence of liquid added mass and added damping on the natural frequency of the valves and actuator, the design method of the cantilever valve was presented. Two micropumps were designed and fabricated for comparing experiments. The micropump with cantilever valves 2.5 mm in length obtained higher output values (the maximum flow rate and backpressure is 3.5 ml/min and 27 kPa, respectively) and had two optimal frequencies (0.8 and 3 kHz). While the micropump with cantilever valves 4.5 mm in length had only one optimal frequency (0.2 kHz), at which the micropump achieved lower output values (the maximum flow rate and backpressure is 3.0 ml/min and 9 kPa, respectively). The study results suggest that the output values and optimal frequency of micropump can be improved by the design of the cantilever valves.

The framework of the Web-based typical mechanical manufacture process management system is studied in details with using for reference of the research production of contemporary technology and process management and designing for technology and process management information and getting down to practicality demand for typical process of manufacturing enterprises. And the expression of the ontology-based typical mechanical manufacture process, and the technologies of process collaborative organized and retrieval are discussed.

Fragile Watermarking could provide an effective solution for both the authentication of image content and the detection of any changes in image. This article puts forward an algorithm of restorable and fragile Watermarking based on fractal compression and differentials record theory. Three components (R. G. B) of a colorful image are processed respectively by fractal compression. In view of cone cells of vision have some differences in sensitivity to color, the compressed data have been stored in B component to restore the colorful image and the R component and G component have been processed with differentials record theory for the detection of any change in image. The presentation of modification precisely approaches pixel-level with the help of the algorithm, and the results of tests have proved a good restorability of this algorithm.