Abstract: Flyover noise measurements were conducted on an aircraft ARJ21 aiming at landing gear noise prediction schemes. The analysis is based on acoustic dedopplerized spectra and localization maps was calculated with the pressure signals of a acoustic phased array with 30 microphones. The acoustic phased array is a spatially distributed set of microphones which simultaneously sample the acoustic field. The doppler shifts was removed using linear interpolation.By appropriately time delaying the output of individual microphones, the origin and level of noise source(the landing gear) can potentially be determined. The success of this approach depends largely on the phased array design, and the array data processing method. This paper focuses on the two areas.
Abstract: Combined time-frequency peak filtering with wavelet modulus maxima, the millimeter wave interferometer echo signal process is presented, extracting the instantaneous frequency(IF) of the projectile in-bore. Based on that, the projectile’s velocity and acceleration curves are estimated and the length of the cannon is also calculated that’s consistent with the actual, which provides a strong basis for designing and improving weapons. And this approach ,with some commonality, can also be used to extract the IF of other signals.
Abstract: A Pattern Recognition method based on wavelet packet and artificial neural is proposed for solid-liquid two-phase flow characteristic parameters and the non-linear relationship between flow pattern. This method firstly established the physical and dynamic model, then set a monitoring point. To get the optimum wavelet tree and its information entropy, six floors of wavelet packet was used to decompose the collected velocity fluctuation signal. Transported the proper vector which is component by information entropy into Back Propagation neural network to train and identify. The recognition results show that this method can effectively overcome the subjectivity of traditional identification methods. It has good recognition effect, thus provide an effective choice for solid-liquid two-phase flow pattern recognition.
Abstract: The output optical power and spectra of a 975 nm semiconductor laser diode (SLD) were measured and analyzed when the SLD was operated with different current in the temperature range of -10°C—65°C. The results showed that the output center wavelength of the SLD shifts in the direction of long wavelength as the operation current and temperature rises. The slopes were approximately 0.24nm/100mA and 0.36nm/°C, respectively. Furthermore, the Conversion efficiency of the SLD was higher when the temperature was low. The reasons for the red shift of SLD was theoretical analyzed.
Abstract: Turbo Code is a channel coding with excellent error-correcting performance in the condition of low noise-signal ratio.It has a superior decoding performance approaching the Shannon limit by adopting the random coding and decoding. This paper focuses on Turbo code and its implementation with FPGA and deeply analyzes the decoding theory and algorithm of Turbo code. Firstly, it analyzes the decoding theory of Turbo code. Then, it discusses key issues in the process of implementation with the most excellent and complicated Max—log—MAP algorithm. At last, it ends up with the Turbo encoder and decoding algorithm which hardware is successfully implemented finally.
Abstract: The image data acquisition module mainly completes the collection of image data and transmits the collected data to the wireless transmission module. This paper mainly discusses the hardware components of the image acquisition module and software implementation. The collected image quality influences image processing, therefore the choice of image sensor is an important part of this system. This is a OV7670 image sensor. The master controller uses C8051F340 MCU. C8051F MC’s frequency has been greatly improved compared with ordinary 51 MCU, and has the advantages of simple structure, interface expansion capability, low prices and better performance.
Abstract: This paper designs a Battery Management System (BMS) based on MCU C8051F350 for 4 series Li-ion battery. It implements the functions of battery pack charge and discharge protection, status display, voltage, current and temperature parameter acquisition and accomplishing RS232 communication between MCU and PC. The analysis of the low-power processing is focused on in the circuit design process. Experimental result shows that this design can reduce power consumption of BMS effectively.
Abstract: While application of field-programmable gate array (FPGA) chip has been extensively investigated, the charging control is relatively unexplored. This paper proposes a flow chart of energy storage for wind power system with Lead-Acid battery whose charging control is constructed by Very High Speed Integrated Circuit Hardware Description Language (VHDL) code. This research focuses on the proposed digital control algorithm can be directly downloaded into field-programmable gate array (FPGA) chip after simulation finishing. This saves greatly time on hardware circuit design. A simulation is presented to illustrate the effectiveness of the proposed charging flow chart.
Abstract: This paper presents an improved ultra-wideband monocycle pulse generator circuit based on step recovery diode. This pulse generator circuit uses short-circuit microstrip transmission line to generate the Gaussian pulse the monocycle pulse. The improved pulse-shaping network employs two schottky diodes and a MESFET to suppress the pulse ringing. The SRD model was built in RF simulation software ADS, and then the design and simulation of the pulse generator circuit was accomplished using this model. The experiments showed an monocycle pulse of 400ps pulse width with good symmetry. The measured results agreed with the simulation.
Abstract: In this paper, design of a LDPC decoder in CMMB is presented. LDPC decoding algorithms for CMMB are analyzed and the optimal decoding algorithm-Normalized MSA are used to implement the decoder, and the algorithm is simulated to determine the design parameters. A partial parallel architecture based on Normalized MSA algorithm is proposed, and the architecture is simulated with a fixed-point model to determine the best quantification scheme for initial information and intermediate data format.