A5103239908- Antenna Design and Optimization
- Underwater Acoustics Research
- Speech and Audio Processing
- Underwater Vehicles and Communication Systems
- Direction-of-Arrival Estimation Techniques
- Ultrasonics and Acoustic Wave Propagation
- Acoustic Wave Resonator Technologies
- Acoustic Wave Phenomena Research
- Surface Treatment and Residual Stress
- Ultrasound and Cavitation Phenomena
- Erosion and Abrasive Machining
- Geophysics and Sensor Technology
- Antenna Design and Analysis
- Indoor and Outdoor Localization Technologies
- Aeroelasticity and Vibration Control
- Structural Analysis and Optimization
- Engineering Applied Research
- Advanced Measurement and Metrology Techniques
- Engineering Technology and Methodologies
- Electrocatalysts for Energy Conversion
- Structural Health Monitoring Techniques
- Advanced Photocatalysis Techniques
- Radio Wave Propagation Studies
- Ultrasound Imaging and Elastography
- Dielectric materials and actuators
Northwestern Polytechnical University
2014-2024
Nanjing University
2024
Nanjing University of Aeronautics and Astronautics
2020
Ministry of Industry and Information Technology
2016
Northwestern Polytechnic University
2006
An analytical and closed-form optimal solution expressed in elementary functions for superdirectivity of a circular sensor array is proposed this paper. By utilizing the circulant property data covariance matrix arrays, such solutions are derived to accurately calculate beamforming vector, beam pattern, corresponding directivity factor, eigenbeams. Based on these solutions, it proved that possesses several important properties which facilitate an eigenbeam decomposition synthesis approach...
This paper presents a detailed study of the high-order superdirectivity circular sensor arrays, which is aimed at completing authors' recently proposed analytical model. From limit expression maximum directivity factor, it shown that arrays possess good potential for improvement. It found sensitivity function used as robustness measurement can also be accurately decomposed into series closed-form functions eigenbeams, similar to optimal beampattern and its corresponding factor. Moreover,...
This letter proposes a robust superdirective frequency-invariant beamforming method for circular sensor arrays. First, the beampattern is accurately transformed into an equivalent form using property of arrays, and expressions directivity factor white noise gain are correspondingly modified. Second, closed-form weighting vector derived based on minimum mean square error approximation to desired that expressed in general form. When number elements sufficiently large, can be further...
A method is proposed to suppress sidelobe level for near-field beamforming in ultrasound array imaging. An optimization problem established, and the second-order cone algorithm used solve obtain weight vector based on response of a transducer array. The calculation results show that can be beam pattern Ultrasound images following application wire phantom are obtained by simulation with Field II program, anechoic sphere experimentally 64-element 26 MHz linear phased experimental agree well...
The solutions of pattern synthesis are derived for circular sensor arrays based on the criterion minimizing mean square error between desired and synthesized beampatterns. Specifically, optimal weighting vector, output beam, minimum all expressed in closed-form exactly when beampattern is properly formulated. These results provide a more effective convenient scheme designing practical frequency-invariant beamformers. Simulations experimental demonstrate performance proposed approach.
To realize the information transmission across water–air interface, radar has been used to detect tiny surface perturbations caused by underwater low-frequency sound source. Due differences of medium properties at it is difficult for targets communicate with airborne platforms directly. solve this problem, we propose finite element method establish minute vibration model on water source, and analyze influence source parameters water. Then design frame structure synchronization signal...
This paper proposes a general model of superdirectivity to provide analytical and closed-form solutions for arbitrary sensor arrays. Based on the equivalence between maximum directivity factor array gain in isotropic noise field, Gram-Schmidt orthogonalization is introduced recursively transformed into matrix form conduct pre-whitening matching operations that result solutions. A mode-beam decomposition synthesis method then presented formally implement these Illustrative examples different...
A method is presented to calculate the driving-voltage weighting vector of a conformal array underwater acoustic transmitting transducers obtain low-sidelobe beam pattern based on measured receiving manifold. The relationship among three quantities given, which are, respectively, radiated field, manifold matrix and transducer array. Then, calculated using optimization pattern. At frequency 12.5kHz, 27-element in an anechoic water tank. proposed method. In addition, computer simulation...
The structure of sound speed in ocean has a strong influence on underwater propagation. For target detection and acoustic communication, it is great significance to obtain the temporal spatial distribution profile. Since limitations applicability vertical grads method structural analysis Indian Ocean, optimal partition developed calculate spring layer. study focuses analysing eigenvalues profiles (SSPs) north-central Ocean based last 10 year data array for real-time geostrophic oceanography....
A method is proposed to calculate the weight vector of a transducer array for ultrasound imaging obtain low-sidelobe transmitting beam pattern based on near-field response vector. An optimization problem established, and second-order
To improve the performance of sonar system mounted on underwater unmanned platform, beam control method compact acoustic transmitting transducer array is studied. For a composed close-packed transducers, many factors can affect directivity, such as position deviation and difference each element, scattering, occlusion effect, mutual coupling among elements, so on. solve this problem, we derive steering vector, propose global optimization to design patterns array, it via second-order cone...
The boundary element method is used to calculate the acoustic radiated field of a complicated conformal array underwater projecting transducers. At first, fundamental theory carefully studied. commercial software Pro/ENGINEER and ANSYS then build model array, SYSNOISE radiation impedance array. technique presented in this paper can be predict performance transducer at stage preliminary design
A free-flooded transducer that couples the vibration of a longitudinal and fluid cavity an aluminum ring was investigated. Given is based on structure has no air cavity, it can resist high hydrostatic pressure when working underwater, which suitable for application in deep sea. At first, principle were introduced. Then, axisymmetric finite element model established; transmitting voltage response, admittance, radiation directivity simulated using method. According to size model, prototype...
A general superdirective beamforming method which is suitable for arbitrary-shape sensor arrays proposed, and its performance linear studied in this paper. Based on Gram-Schmidt orthogonalization, the optimal solutions of superdirectivity are all expressed closed-form without any approximations. The beampattern maximum directivity factor decomposed into mode-beams their associated factors respectively. For arrays, mode-beam increases as order number increases, but robustness decreases. Thus,...