The field distribution, overlap integral and the relationship between driving power and waveguide thickness variation of surface acoustic wave (SAW) acousto-optic modulator based on 165°Y-cut 75°Y-propagation LiNbO3 (165Y LN) has been simulated theoretically in this paper, and compared with the simulation results in other cut direction. This cut direction is located within the material decoupling surface and has the highest electromechanical coupling factor coefficient, making it a potential high performance cutting direction. The test results show that both TE and TM modes of 165Y-LN have lower driving power and larger overlap integral bandwidth at low frequency range, which makes 165°Y-75°Y LN suitable for fabrication high performance and polarization-insensitive SAW acoustic-optic devices.

In this paper, a design method for obtaining an ultra-wideband thin film bulk acoustic resonator (FBAR) filters based on aluminum nitride thin film with a relative bandwidth of about 70.61% has been proposed, that is a bandwidth of 4.835 GHz at a center frequency of 6.5 GHz. The simulation result shows that by series-parallel inductance and series-parallel capacitance at the inductance end, the influence of harmonic resonance point interference caused by adding external inductance on the bandpass can be eliminated, realizing the ultra-wideband of FBAR filters. This work opens up a new way to design ultra-wideband bulk acoustic wave filters with bandwidths exceeding 3 GHz.

A liquid droplet atomization device based on surface acoustic waves was designed and fabricated to address the issues of high energy loss, wide particle size distribution, and difficulty in generating large quantities of micro- and submicron-sized droplets using current atomization devices. First, the structure of the surface acoustic wave device was modeled using COMSOL simulation software and subjected to piezoelectric simulation analysis, simulating the vibration propagation of the surface acoustic wave and obtaining a resonant frequency of 18.269 MHz. Second, based on the acoustic-piezoelectric coupling multiphysics field, the diffraction of sound waves at the solid-liquid interface and the propagation of sound waves in the liquid were simulated. Finally, a surface acoustic wave atomization experimental device was fabricated to perform liquid droplet atomization experiments. By adjusting the excitation signal frequency and input power, stable atomization of droplets is achieved, and the droplet size distribution after atomization is tested. The experimental results showed that under the conditions of an input signal amplitude of 420 mV and a resonant frequency of 19.259 MHz, the device generated a large number of small micron-sized droplets with a droplet size distribution showing three peaks mainly concentrated at 3 μm, 30 μm, and 500 μm.

The design method of fan-shaped SAW filter using leaky wave propagating on LiTaO3 substrates is proposed in this paper. The electromechanical coupling coefficient (ΔV/V) of 36°Y-X LiTaO3 substrates is 2.4%, and the temperature coefficient of frequency (TCF) is -32×10-6/℃. The 36°Y-X LiTaO3 has strong piezoelectric coupling characteristic and moderate temperature stability, based on it, the designed SAW filter with 5%~10% fractional bandwidth can achieve less insertion loss and moderate temperature stability. The measured results of fabricated device are consistent with the simulated ones.

Based on surface acoustic wave (SAW) filter technology, a miniaturized component with high stop-band suppression has been developed using methods such as two-stage filter cascade, filter surround switch, and multi-channel anti-interference layout. The experimental results indicate that the developed multi-channel filtering component has a size of 18 mm×15 mm×5 mm, with -3 dB bandwidth of greater than 48 MHz, insertion loss of less than 7 dB, in-band amplitude fluctuation of less than 1.5 dB, and near-end stop-band suppression of greater than 70 dBc. It has good practicality.

The mainstream process for inter-connecting SAW devices is AlSi wire ultrasonic bonding, and the heel micro-crack is the biggest quality hazard of this process. According to principle and process of ultrasonic bonding，the factors causing the heel micro-crack are analyzed in this paper, and the corresponding solution is given. The proposed scheme can effectively control the heel micro-crack at the bonding points of SAW devices.

In order to investigate the mechanical properties of non-uniform piezoelectric semiconductor (PS) fiber, the physics-informed neural network model (PINN) is proposed in this paper, and a deep learning algorithm is applied to solve the partial differential equations with variable coefficients. Taking the static extension of PS fiber with variable cross-section as an example, a deep neural network is firstly established as a trial function, and then substituted into the governing equations of PS to form a residual and used as the weighted loss function for the machine learning. Then, the numerical solution is approximated through the deep machined learning. The research results indicate that the presented method has wide applicability, and can be used to solve the linear and non-linear governing equations of PS materials with arbitrary cross-section.

The Bi2O3 doped Ba0.85Ca0.15(Zr0.1Ti0.88Mn0.02) O3 piezoelectric ceramics were prepared by solid state method, the microstructure of the system and the effect of Bi2O3 doping amount on the piezoelectric properties of the system were studied. The sample with the best performance of the system was assembled into a micro air pump and compared its performance with the MZB1001T02 micro air pump from Murata, Japan. The results show that the lead-free piezoelectric ceramics of Bi2O3 doped Ba0.85Ca0.15(Zr0.1Ti0.88Mn0.02) O3 exhibit a single perovskite structure, and a small amount of Bi2O3 doping makes the system keep the coexistence of trigonal phases and tetragonal phases. When the doping amount is 0.05 wt%, the distribution of grains is uniform and the dielectric and piezoelectric properties of the samples are the best, i. e.εT33=5 289,kp=0.46,d33=377 pC/N,tan δ=0.72%、Tc=80 ℃,and the sample exhibits typical dielectric relaxation characteristics. The above sample was assembled into the micro air pump, and under the conditions of input frequency of (25±2) kHz，input voltage of 15 V, the measured air pressure of the micro air pump was slightly lower than that of the micro-pump of Murata , Japan. The sample can be applied to some areas of low pressure requirements.

In response to the problems of complex processing technique and high cost in the existing piezoelectric-actuated cantilever resonators, this paper proposes a new piezoelectric-actuated cantilever resonator stack structure based on an aluminum nitride support layer, which not only effectively reduces the processing difficulty, but also maintains a high quality factor while miniaturizing the device. The relationship between resonator quality factor and device size design at a fixed frequency is investigated through theoretical analysis, and the effects of different support layer materials on the resonator quality factor are compared. The effect of electrode size design on the performance of resonator in vacuum is investigated experimentally, and the optimum design of piezoelectric-actuated aluminum nitride based cantilever resonator operating in out-of-plane flexural vibration mode is determined. The test results show that the resonator exhibits the best performance when the electrode width ratio is 1 and the length ratio is 2/3, with the quality factor of 7 786, the corresponding resonant frequency of 63.44 kHz, and motion impedance of 66.70 kΩ.

In order to realize precise positioning of large displacement stroke and no coupling motion, a x-y-θz 3-DOF parallel piezoelectric micro-positioning stage with compact structure and large worktable is designed. Firstly, in this paper, the driving unit of the stage is designed by using the compliant bridge amplification mechanism of double flexible plates, and the body of the stage is designed based on the compliant mechanism of double parallel four-link, thereby obtaining the overall structure of the stage. Secondly, the finite element method is used to analyze the stress, displacement amplification and mode of the stage. Finally, an experimental system for the designed micro-positioning stage is built, and the displacement and frequency response characteristics of the stage are tested. The experimental results show that the maximum output displacement of the stage in the x direction is 306.1 μm and the coupling rate is 0.26%, the maximum output displacement of the stage in the y direction is 402.3 μm and the coupling rate is 0.14%, and the maximum rotation angle in the θz direction (i.e. around the z axis) is 2.72 mrad. The displacement resolutions of the stage in x, y and θz directions are 10 nm, 10 nm and 0.1 μrad, respectively, and the natural frequencies are 104.1 Hz, 130.0 Hz and 115.6 Hz, respectively.

The piezoelectric drive flexible micro/nano positioning platform usually presents a low-damping resonance mode, and it is easy to excite mechanical resonance during high-speed motion, which seriously affects the stability of the control system, control bandwidth and trajectory tracking accuracy. In order to eliminate the dependence of the current resonant controller on the platform dynamics modeling accuracy, an adaptive notch filter is designed to realize the online real-time resonance suppression of the piezoelectric micro/nano positioning platform. Firstly, a piezoelectric drive flexible micro/nano positioning platform system is built and its electromechanical coupling dynamic model is established. Secondly, the fast Fourier transform method is used to analyze the closed-loop system error signal online, and the platform frequency characteristic extraction algorithm is designed to realize the online adaptive tuning of notch filter parameters. Finally, the designed adaptive notch filter is used to carry out trajectory tracking experiments on step signal and triangle wave signal. The experimental results show that the adaptive notch filter can achieve online suppression of resonance, which can effectively improve the stability and trajectory tracking accuracy of the platform.

A closed cylindrical micro inertial impact piezoelectric motor structure is designed to meet the requirements of linear micro feed drive motor for precision instruments and micro devices, and the feasibility of the operating principle of the motor is verified. A prototype motor is fabricated and tested experimentally. The results show that when the preload is 0.25 N, the peak-peak value of the sawtooth voltage of the driving signal is 50 V, and the frequency is 500 Hz, the maximum speed of the no-load output of the motor is 6.19 mm/s, and the step resolution is 12 μm; When the preload is 0.5 N, the peak-peak value of the driving signal voltage is 50 V, and the frequency is 500 Hz, the maximum load force is 20 g.

The temperature affects the performance of the accelerometer, and the main source of error is caused by the thermal stress generated by quartz materials and packaging processes. In response to the temperature drift phenomenonr, this article introduces the design and compensation method of the low-temperature drift structure of the integrated quartz resonant accelerometer. Firstly, the first-order temperature coefficient is eliminated by a symmetrical differential structure, and the process optimization is carried out to reduce the thermal stress generated by the packaging process on the resonator. Secondly, the random forest fitting algorithm is used to establish a temperature model to compensate for the temperature drift of the accelerometer. The temperature drift test of the accelerometer prototype is carried out within the temperature range of -20~80 ℃, and the results show that the bias stability of the prototype has been improved by an order of magnitude after process optimization and compensation.

In order to facilitate the driving of the antisymmetric mode of the resonant beam and improve the sensitivity of acceleration detection, a distributed electrode driving method is proposed in this paper. The distributed electrode can drive the antisymmetric mode of the resonant beam and detect the signal more easily. The elastic beam mass block system is designed to be used as the sensitive mass for sensing external acceleration, and the resonant beam is used as the sensitive element for measuring acceleration. The first two order dynamics equations of the resonant beam are established. The first and second order frequencies of the resonant beam are measured under different accelerations. The experimental results show that the positive sensitivity of the second order mode detection is increased by 49% and the negative sensitivity is increased by 89%, and the quality factor of the second order mode detection is 3.19 times that of the first order mode. Finally, the influence of bias DC voltage on sensitivity is analyzed. With the increase of voltage, the sensitivity of positive acceleration detection increases, while the sensitivity of negative acceleration detection decreases.

In order to meet the requirements of the integrated gyroscope chip for high-precision masses, this paper adopts the electron beam physical vapor deposition (EBPVD) instead of traditional electroplating process to form the masses with a thickness of about 2 μm at the tips of tuning fork. The thickness uniformity, alignment accuracy and film adhesion of the masses are investigated. Firstly, by adjusting the height and angle of deposition, the thickness requirements are met. Secondly, in order to ensure the alignment accuracy, the metal mask jig and wafer adjustment jig are designed. Finally, the optimal deposition parameters are determined through experiments. In addition, the laser trimming experiment on the fabricated masses is carried out. After trimming, the amplitude of the mechanical coupling error of gyroscope is decreased from the initial value of 301.0 mV to 17.6 mV.

In situations such as emergency rescue and individual combat where GNSS signals are denied and navigation and positioning infrastructure cannot be set up, the Pedestrian Dead-Reckoning (PDR) technology based on Inertial Measuring Units (IMU) is usually used to measure Pedestrian gait information. According to the formation characteristics of such mission with multi-person operations, the ultra-wideband (UWB) technology is used to implement formation Ad Hoc network and mutual inter-network ranging. The PDR/UWB multi-pedestrian extended Kalman filter (EKF) model is established. By constraining PDR with the ranging information, the divergence of PDR positioning accuracy with time is effectively alleviated, and the multi-person cooperative navigation is realized. The experimental results show that the centralized cooperative navigation system based on UWB can improve the overall positioning performance of formation by 30% without relying on infrastructure.

The traditional system-level calibration method regards the random noise caused by the thermostat compressor, turntable motor and other environments as white noise, but the output signal in the actual process has non-stationary and nonlinear characteristics, while the least squares fitting method is a linear regression, the error coefficient solved by this method becomes one of the key factors restricting the high precision of the fiber optic strap-down inertial navigation system. Aiming at the above-mentioned problems, an improved SINS system-level calibration algorithm based on Hilbert-Huang transform is proposed. The high-frequency random noise in the original output signal of the inertial instrument is removed based on Hilbert-Huang transform, and then the IMU error parameters are calculated by the system-level calibration improved method. Through multiple sets of experiments, it has been proved that this method can effectively improve the accuracy of IMU error parameter identification, and the dynamic navigation position error of 1 h is relatively reduced by about 10%.

Digital filter is one of the key technologies that affect the quality of marine gravity data processing results. A real time positive and negative finite impulse response(FIR) filtering algorithm is proposed and the expression of the positive and negative FIR filter with linear phase is derived. The filter designed by this algorithm satisfies the strict linear phase-frequency characteristics in all sampling spectrums, and will not cause nonlinear distortion to the signal; The low-pass filter designed by the algorithm has a large stop-band attenuation, which is beneficial to suppress high-frequency noise in ocean gravity data. The ship-borne test shows that the filtering effect of the positive and negative FIR filter is better than that of the traditional FIR filter in ocean gravity data processing, and comparable to offline processing results.

To improve the detection performance of sonar systems, this paper develops a broadband highly sensitive hydroacoustic transducer with a "pyramidal" structure. Selected The single metal plate air column type piezoelectric material is selected as the active material for broadband high sensitivity transducer. The electromechanical equivalence analysis and finite element simulation of the sensitive element are carried out to obtain the preferred range of piezoelectric material size. The "pyramid" shaped transducer sensitive element structure is designed according to the multimode coupling theory. A broadband highly sensitive transducer prototype has been developed by establishing the transducer fabrication process. The test results show that the highest transmission voltage response is up to 182.9 dB, transmission bandwidth is 170 kHz, the highest receiver sensitivity is up to -173.7 dB, receiving bandwidth is 110 kHz, and a -6 dB beam opening angle is 8.1°.

In this paper, a Mach-Zehender interference temperature sensor with high sensitivity is introduced. A section of polarization-maintaining fiber is embedded between single-mode fiber, and by overlapping extrusion discharge to form a reverse convex cone, a sensor with a structure of single mode fiber-polarization-maintaining convex cone fiber-single mode fiber is realized. The convex cone structure increases the energy of the cladding mode and improves the contrast of the transmission spectrum of the sensor. The experiments show that when the length of polarization-maintaining fiber is 2.5 cm, the maximum temperature sensitivity reaches 126.45 pm/℃ within the range of 30~70 ℃. In addition, in this paper, the main components involved in mode interference are analyzed by calculating different polarization modes and corresponding mode propagation constants, thereby verying the accuracy of temperature sensitivity measurement. The sensor with this structure has the characteristics of compact structure, small size and simple manufacturing process, which can be applied to temperature sensing measurement.

The high temperature piezoelectric accelerometers are widely used in vibration and impact testing, fault diagnosis and monitoring. In order to address the problem of excessive temperature drift in the sensitivity of conventional piezoelectric accelerometers, a high temperature piezoelectric accelerometer is designed in this paper. The accelerometer adopts a design of stacked piezoelectric elements with positive and negative temperature coefficient to counteract the effect of temperature variation and thereby reduce temperature drift. A compression-mode piezoelectric accelerometer is constructed by stacking 5 layers of YCOB piezoelectric elements and 1 layer of GdCOB piezoelectric elements. The performance of the accelerometer was simulated and optimized using ANSYS, and the effectiveness of the proposed method for reducing sensitivity temperature drift was verified through simulation. The results show that the sensitivity temperature drift of the designed accelerometer is less than ±3% over the full temperature range from room temperature to 800 ℃, and it has the advantages of good high temperature stability and high measurement accuracy.

In recent years, with the increasing integration of missile-borne electronic equipment and the increasing internal heat consumption, how to achieve efficient thermal management of equipment has become a major challenge restricting the further development of missile-borne electronic equipment. In this paper, a phase change heat storage module applied to high-power missile-borne microwave combination is proposed Through simulation analysis, the influence of the main structure of the thermal storage module on the overall heat storage capacity of the heat storage module is studied. After comprehensively considering various factors such as manufacturability, quality, heat storage capacity, the structural form of the heat storage module and the final phase change medium material has been confirmed. A sample of heat storage module was processed by using the additive manufacturing technology, and a thermal test platform was built to evaluate the heat dissipation effect. The experiment shows that the total heat consumption of the module is 211 W at 60 ℃, and the maximum surface temperature of the module is 104.1 ℃ after 10 min of operation, which meets the operating conditions of the microwave combination. The heat storage design technology can effectively solve the problem of high temperature rise under the conditions of short-time and high power of the module, and has broad application prospects in the field of thermal management of missile-borne electronic equipment.

According to the requirements for ultra-wideband transmission in communication systems, a high isolation dual band-notched ultra-wideband(UWB)multiple-input-multiple-output(MIMO)slot antenna with coplanar waveguide(CPW)feed was designed in this paper. The antenna printed on a FR4 dielectric substrate consists of two orthogonally placed radiation patches, which are a gradual structure combining rectangular and semicircle shapes. The interferences of WLAN and X-band were suppressed by etching C-slot on the radiation patch and loading SRR branch on the back of the radiation patch. The isolation of the proposed MIMO antenna is improved by introducing a fence-shaped branch. The measured results show that the operating bandwidths of the antenna is 3.0-10.66 GHz，the port isolation(S21)within this range is less than -27 dB. The antenna has notched-band characteristics at 5.11-5.96 GHz and 6.82-7.86 GHz. The envelope correlation coefficient(ECC)is less than 0.03. The antenna can be applied to the UWB MIMO communication systems requiring suppression of interference from multiple narrowband signals.

In this paper, a metasurface with "cross-ring" shaped structure is designed, and a 2-bit coding Phase-Gradient Metasurfaces (PGMS) design is implemented. Based on the characteristics of metasurface array, a GAPSO-APS optimization algorithm combined with the improved genetic algorithm and particle swarm optimization (GAPSO) and array pattern synthesis (APS) is proposed to obtain the optimal arrangement of the metasurface coding matrix, thereby achieving significant reduction of the broadband radar scattering cross section (RCS). The simulation of the designed metasurface is carried out and compared with the metallic surface. The results show that the designed coding metasurface can achieve 10 dB RCS reduction in the frequency band from 3.1 GHz to 29.7 GHz, thus verifying the effectiveness of the designed coded metasurface in achieving RCS reduction in the wide frequency band and the effectiveness of the algorithm.