Liu Y.,Science and Technology on Underwater Test and Control Laboratory |
Zhang L.,Science and Technology on Underwater Test and Control Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017
With the rapid development of the shipping industry, the number of the world's ship is gradually increasing. The characteristics of the radiated noise of the ship are also of concern. Since the noise source characteristics of multichannel interference, the surface wave and the sea temperature microstructure and other reasons, the sound signal received in the time-frequency domain has varying characteristics. The signal of the radiated noise of the large cargo ship JOCHOH from horizontal hydrophone array in some shallow water of China is processed and analyzed in the summer of 2015, and the results show that a large cargo ship JOCHOH has a number of noise sources in the direction of the ship's bow and stern lines, such as host, auxiliary and propellers. The radiating sound waves generated by these sources do not meet the spherical wave law at lower frequency in the ocean, and its radiated noise has inherent spatial distribution, the variation characteristics of the radiated noise the large cargo ship in time and frequency domain are given. The research method and results are of particular importance. © 2017 SPIE.
Tian Z.,Science and Technology on Underwater Test and Control Laboratory |
Jiang K.,China Institute of Technology
2016 IEEE/OES China Ocean Acoustics Symposium, COA 2016 | Year: 2016
In order accurately to calculate the transmission loss of sound waves in air from an underwater sound source, a sound propagation loss calculation model was established based on an underwater virtual sound source and geometrical acoustics. Viewed in the air, sound waves seem to spread from a virtual source located at a point underwater in the reverse extension line of the refracted sound rays. Thus the spreading loss of wave surface in the air should be calculated in accordance with the centre of the sphere at the place of virtual source. In the case of two very near sound rays emitted by the sound source, the reverse extension lines of their refracted sound rays necessarily intersect at the underwater virtual source. By finding the derivative of both sides of the Snell's law equation expressed by the product form, the derivatives of the incidence angle and the reflection angle in the relationship would be eliminated. It would then be able to determine the distance from the virtual source to the incident point and also the depth of the virtual source, which in turn would make it possible to calculate the sound transmission loss accurately in air. The measured and calculated values conform quite well, which indicates that the method is correct. © 2016 IEEE.
Tian Z.X.,Science and Technology on Underwater Test and Control Laboratory |
Yu F.,China Institute of Technology |
Liu Z.W.,China Institute of Technology
Applied Mechanics and Materials | Year: 2013
To resolve the problem of acquiring multi sensors signals synchronously in a distributed system, a project of distributed synchronous data acquisition based network time server was designed. The system comprised multi distributed sensor units, a centralized control unit and D&C (display and control) center. Each sensor unit was equipped with a data acquisition module. All data from sensor units were concentrated and sent to the D&C center, and the D&C center implemented power supply and management of sensor units via the centralized control unit. To synchronize the data acquisition modules, a network time server was employed in the D&C center. It received standard time information from GPS and outputted the time signal with DCF77-encoding. Each data acquisition module received and decoded DCF77 time signal, obtaining absolute time and synchronizing its time base. Above project was applied successfully in a system comprising 20 distributed sensor units. The results prove the designs feasible. © (2013) Trans Tech Publications.
Zhang Y.,Dalian University of Technology |
Zhou Z.,Science and Technology on Underwater Test and Control Laboratory |
Wang J.,Dalian University of Technology |
Li X.,Dalian University
Materials and Manufacturing Processes | Year: 2013
As a hard-to-machine material, titanium alloy has a combination of superior heat resistance, corrosion resistance, and mechanical properties, and this leads to poor machinability. High cutting forces and cutting temperature greatly accelerate tool wear during the cutting of titanium alloy frequently. In this article, the ultrasonic vibration turning method was adopted to reduce the wear of diamond tool in the turning of TC4 titanium alloy. Ultrasonic vibration turning tests were carried out in a variety of cutting parameters. The experimental results indicated that the wear of diamond tool was significantly reduced during the turning of TC4 using the ultrasonic vibration turning. In the ultrasonic vibration machining tests, the tool vibration amplitude and frequency are the primary and most influential factors on tool wear, followed by the feed rate and then the cutting depth. © 2013 Copyright Taylor and Francis Group, LLC.
Zhimin Z.,Science and Technology on Underwater Test and Control Laboratory |
Xiaoyan L.,Dalian University of Technology
Applied Mechanics and Materials | Year: 2012
Titanium alloys, as difficult-to-cut materials, have poor machinability due to their superior mechanical properties, heat resistance and corrosion resistance. High cutting temperature and great cutting force that will greatly accelerate tool wear often occurs in titanium alloys cutting process. In this paper, an ultrasonic vibration turning method was used to lower diamond tool wear during TC4 titanium alloy turning process. Ultrasonic vibration turning tests were carried out with various cutting parameters. Experimental results indicated that there's a significant reduction of the wear rate of diamond tools by means of ultrasonic vibration in TC4 turning process. For ultrasonic vibration turning, spindle speed, the amplitude and frequency of vibration of the tool are the greatest impact of tool wear, followed by feed rate, then the cutting depth. © (2012) Trans Tech Publications, Switzerland.
Wan L.-T.,Harbin Engineering University |
Liu L.-T.,Harbin Engineering University |
Si W.-J.,Harbin Engineering University |
Tian Z.-X.,Science and Technology on Underwater Test and Control Laboratory
The Scientific World Journal | Year: 2013
Each element in the conformal array has a different pattern, which leads to the performance deterioration of the conventional high resolution direction-of-arrival (DOA) algorithms. In this paper, a joint frequency and two-dimension DOA (2D-DOA) estimation algorithm for conformal array are proposed. The delay correlation function is used to suppress noise. Both spatial and time sampling are utilized to construct the spatial-time matrix. The frequency and 2D-DOA estimation are accomplished based on parallel factor (PARAFAC) analysis without spectral peak searching and parameter pairing. The proposed algorithm needs only four guiding elements with precise positions to estimate frequency and 2D-DOA. Other instrumental elements can be arranged flexibly on the surface of the carrier. Simulation results demonstrate the effectiveness of the proposed algorithm. © 2013 Liang-Tian Wan et al.
Si W.,Harbin Engineering University |
Wan L.,Harbin Engineering University |
Liu L.,Harbin Engineering University |
Tian Z.,Science and Technology on Underwater Test and Control Laboratory
Progress in Electromagnetics Research | Year: 2013
The pattern of each element in conformal array has a different direction for the curvature of conformal carrier, which results in polarization diversity of conformal array antenna. Polarization parameters of incident signals are considered in snapshot data model in order to describe the polarization diversity of conformal array antenna. It is required that the polarization parameters and direction of arrival (DOA) of incident signals are estimated together. An integrated frequency and DOA estimation method is proposed in this paper for cylindrical conformal array antenna. The frequency estimation of signal source is obtained by constructing state-space matrix. Through well-designed configuration of elements on cylindrical carriers along with estimation of signal parameters via propagator method (PM), the decoupling scheme for DOA and polarization parameters is implemented. A novel parameter pairing method for frequency and DOA of multiple sources utilizing the interpolation technique is given, based on which the fast frequency-DOA estimation algorithm is developed. Effectiveness of the proposed method is demonstrated by simulation experimental results.
Tian Z.X.,Science and Technology on Underwater Test and Control Laboratory
Applied Mechanics and Materials | Year: 2013
To resolve the problems of short working life and narrow operating voltage range of the spark gap with one-offin gas filling structure, a spark gap with repeatable gas filling structure was designed. The spark gap was composed of three electrodes and two gaps as well as gas filling devices. Electrodes structures adopted the form of field aberration three-electrode gas spark switch forming two discharge gaps between three electrodes of anode, cathode and triggering electrode. Gas filling devices were composed of fast connector, gas pipe, barometer and air valve, by which the gaps could be repeatedly charged and deflated from a hole at the center of anode. Working life is lengthened by exchanging gas, and operating voltage range is widened by changing gas pressure in a certain range. The spark gap was manufactured and applied successfully in a TEA CO2 laser with pulse energy 170J. The results prove the designs feasible. © (2013) Trans Tech Publications, Switzerland.
Liu Y.L.,Science and Technology on Underwater Test and Control Laboratory
Applied Mechanics and Materials | Year: 2014
Virtual Instrument as the fifth-generation instrument has been a new technology with its unique advantages and got applying and developing more and more widely. From the view of composition and characteristics of the virtual instrument, the paper expounds the designing and developing process of electric field sensor calibration system based on the Ethernet and GPIB communication protocols. The table of the electric field sensor calibration system developed in the paper with a friendly interface improves the work efficiency of the electric field sensor calibration greatly, and the method and process of developing the electric field sensor calibration system could be a reference for the development of other relevant virtual instruments. © (2014) Trans Tech Publications, Switzerland.
Yuan P.,Science and Technology on Underwater Test and Control Laboratory
Proceedings - 2011 IEEE International Conference on Computer Science and Automation Engineering, CSAE 2011 | Year: 2011
In the paper, based on the analysis to several feature selection methods, such as principle component analysis (PCA), maximal gradient selection and exploratory pursuit are presented. First merits and demerits of several methods are compared. Then to true and false underwater target echo signal, Wigner and Burg features are extracted and selected by those methods. Finally, the selected features are trained and recognized by Fuzzy Adaption Resonance Theory (FART) network to compare the effect of several methods to the two kinds of echo signal. The number of training samples to the number of testing samples ratio is 1 to 4. The results show the two kinds of method, maximal gradient selection and exploratory pursuit are not only less computation but also low dimension. The higher recognition can be achieved by the two methods. © 2011 IEEE.