Abstract:Experiments are performed to investigate the effect of plasma power supply voltage and the numbers of plasma actuator electrodes on the flow control effectiveness of the test cylinder. It is demonstrated that with a higher actuating voltage, an enhanced flow disturbance could be attained, and a better flow control effectiveness is achieved. It is also observed that when more electrodes are activated, larger area of boundary layer would be activated, which is beneficial to enhancing the flow control effectiveness.

Abstract:In order to avoid crack and fracture of the second stage rotor blade of a certain aero-engine low compressor, a new remodel plan is used. That is to thicken the rotor blade and to strengthen the flange. The mechanic properties of the blade and the disc before and after being remodeled are studied in this paper so as to verify the intensity and its influence on the disc. The conclusion is that the stress distributions on the blade and on the disc are not changed and, the magnitudes and the intensity of the stress all meet the design standards. These jobs provide a theoretical basis for replacing the unimproved blades by the improved ones and a theoretical foundation of preventing the blade and the disc from cracking and fracturing.

Abstract:A thorough research for some engine synthetic electronic regulator false warning problem is conducted. The self-locking mechanism of the low- pressure air compressor stator vane after the regulating channel false warning is analyzed. And the plan for solving the problem is proposed. The automatic circuit of eliminating the self-locking is designed and realized. Through the installation and the test on the airplane, this electric circuit in the air can relieve the self-locking breakdown caused by the false warning, thus enhancing the system reliability.

Abstract:In view of the high cost of aero-engine test platform, in combination with virtual reality and visualization technology and via VC ++ software platform and OpenGL graphic software interface, the simulation platform of the virtual aero-engine compressor is established. Simulation platform software system can be used to test and predict the performance of compressor. This software system has provided a lifelike and vivid condition for experiments. Therefore, it is a reliable, economical and efficient way of teaching in experimental class, training for operation and designing verification, research on simulation etc.

Abstract:Using the method of variable specific heat and in consideration of the volume effects of the internal parts, a dynamic model for turbofan engine is established. The numerical simulation for the dynamic process of turbofan engine is calculated as the gas pumping coefficient for power pumping or turbo cooling changes, and the results indicate that the gas pumping coefficient affects the working of aero engine greatly, when the coefficient rises, the stall margin of the LP compressor decreases and that of the HP compressor increases. So different coefficients affect the turbo engine differently.

Abstract:The requirement for the normal use of pavement is less considered in the traditional airport pavement design in frigid area, so the frost heave is brought on the pavement in winter. Based on deducing the stress acted on the base surface begotten by frost heave, and from the point of view of energy balance, the analytic formula of frost heave stress acted on the base bottom is deduced. The result has been checked in the frozen soil experiment in the airport reconstruction project, the error is 2%. This presents that the analytic formula is efficient and feasible in the design of both airport pavement and cement concrete read layer.

Abstract:The control problem of chaotic system is investigated starting with a class of more generalized nonlinear chaotic system. An adaptive sliding mode variable structure control scheme for Lorenz chaos is presented. Using the proposed control scheme the state of chaotic system can be asymptotically driven to a appointed equilibrium point in spite of the presence of input saturation and external disturbance. Numerical simulations demonstrate the effectiveness of its application to chaotic system control.

Abstract:Aiming at ballistic missile attacking, a two-sided optimal decision model used for ballistic missile attack - defense is put forward, asynchronous branch and bound algorithm is designed. Given a complete missile attack plan and a responding defense, expressing the enemy courses of action as a mathematical model which can cause maximum expected damage, and then the problem how to optimize our defensive interceptor pre-positioning to minimize the maximum achievable expected damage is shown and explained. A simulation instance that can show the validity of the two - sided optimal decision method used for ballistic missile attack-defense is given at last.

Abstract:This paper considers the problem of the Armijo step-size gradient - descent algorithm for optimal control of switched dynamical systems as an object of study. An expression of the gradient of the cost functional is given and proved. The simulation results show that the Armijo step-size gradient - descent algorithm is good in adaptability to optimal control of switched dynamical systems.

Abstract:The ultra-wideband (UWB) scattering characteristics of targets are computed by using the method of FDTD with Unsplit-field Perfectly Matched Layer (UPML) boundary condition. UPML absorbing boundary condition needs less storage by introducing auxiliary equations. The ultra-wideband bistatic RCS of F117A fighter is computed in this paper. The computation results are compared with the results in Ref. 1 and both accord with each other well.

Abstract:A novel bi-directional micro-strip antenna fed by coplanar wave-guide (CPW) is proposed to obtain circular polarization (CP) radiation. Two square patches, fed by coupling through the CPW open stub, are selected as the radiating elements. Perturbation segments are added at different sides of the square patches. Same rotation CP radiations in two opposite directions are achieved by adding perturbation segments. The symmetrical characteristics of the antenna suppress the even mode in the CPW line. Measured results show that the proposed antenna has a -10dB return loss bandwidth of 11.6% and a CP bandwidth of 1.86%. Left-hand circular polarization (LHCP) appears on both sides of the antenna. The theoretical results accord with the measured results well.

Abstract:Most traditional maneuvering targets tracking algorithms are excessive in relying on the adopted targets motion models, and without making full use of the information of the measure series, so the tracker's performance declines when the targets are maneuvering. Aiming at the problem described above, a new algorithm is derived. The algorithm can be used to adjust the filtering results of a traditional algorithm with targets' course maneuvering series. The simulation results show that tracking precision of the new algorithm is higher than that of the traditional algorithms, so it is simple and effective adaptive maneuvering targets tracking algorithm.

Abstract:D-S Evidence theory and Rough Sets can complement each other in processing uncertainty information. To the problem of subjectivity in getting Basic Probability Assignment of D-S Evidence theory for multi-sensors data fusion, a new method of getting evidences and objective BPA by decision table is proposed by defining Rule Intensity and Decision Expansion Rule integrated with Rough Sets theory. The correctness and validity of the developed method are verified with a particular instance.

Abstract:A method of the electro hydraulic servo system identification modeling is presented based on support vector machines. The model of the electro hydraulic servo system based on support vector machine is established by using the measurable parameters of the system. The simulation test is carried out for electro hydraulic position servo system. The results show that the model of support vector machine has the advantage of high identification precision and of good generalization characteristic. So the method mentioned above is valid.

Abstract:This paper proposes a hardware implementation scheme for the fractal modulation and demodulation system based on Mallat algorithm and polyphase filter, and the shaping and synchronization system are also designed. According to the weakness of false synchronization and high sensitivity to timing error, the carrier phase recovery is combined with frame synchronization on the basis of maximum likelihood (ML-) estimation, and at the same time the false synchronization can be detected and corrected. The simulation results indicate that the scheme is feasible and effective.

Abstract:Based on the generalization of MUSIC method and the signature sequence of users, a new method is proposed to estimate multi-path time delay for CDMA personal station. This method is helpful to utilizing the received information of user instead of pilot signal, its advantage is that the user in the edge of cell may exploit simultaneously the signals transmitted by several base stations to implement multi-path diversity and improve the performance of communication.

Abstract:This paper introduces the concept and realization of Embedded Internet technology, analyzes the reasons for simplifying TCP/IP in embedded system, elaborates the main working courses of DSP and NIC, and then designs a scheme of "embedded TCP/IP" based on DSP. The testing result shows that this network terminal functions smoothly in data exchange with PC in LAN.

Abstract:An evaluation method of a fighter's supportability is presented based on entropy weight. With the judging matrix only and without the specialist's weight, this method is employed in computing the entropy weight of multi-index evaluation matrix with multi-objects, and estimating many fit schemes, so the best choice is selected and an optimized scheme with a better reliability is got.

Abstract:A blind adaptive multi-user detection based on RLS algorithm is presented, and the algorithm's convergence dynamics for suppressing MAI (Multi-Access Interference) is analyzed. These demonstrate that the detection based on this algorithm finally converges to a constraint MMSE detection without training sequence. The simulation results under AWGN-Additive White Gaussian Noise channel and Rayleigh fading channel are presented.

Abstract:A new intermediate frequency digital demodulating method is proposed based on orthogonal device and feed-forward implementation, which can be easily implemented on universal communication system. The main algorithm of this demodulating method, including frequency offset estimation algorithm and timing recovery algorithm, is also discussed in detail. The mean square error (MSE) performances of these two main algorithms and of the bit error ratio (BER) of this demodulating method are simulated. The computer simulation result demonstrates the validity of this new intermediate frequency digital demodulating method.

Abstract:This paper describes a new speech coder at 600 bps based on the enhanced mixed excitation linear prediction (MELPE) algorithm, which is the new NATO standard STANAG 4591. The algorithm of this speech coder includes features of MELPE. Multi-frame joint vector quantification is performed, which takes advantage of inherent inter-frame redundancy. The predicted multi-stage vector quantization (PMSVQ) algorithm is designed to quantize the line spectrum frequency (LSF) parameters. The informal subjective quality tests show that the speech quality of the proposed coder is better than that of LPC10e and approximates to 2.4 kbps MELP standard.

Abstract:Performance of MUSIC algorithm for direction finding in the presence of channel mismatch is analyzed. The concrete formulas of deviation and variance of DOA (direction of arrival) with only one source impinging on an array are derived in this paper. Simulation results indicate that the formulas derived in the paper are correct.

Abstract:In the process of image super-resolution reconstruction, there is a need for interpolating pixels in the low- resolution image. On the basis of detecting the edge of low-resolution image and in consideration of its direction, the pixels belong to edges in the reconstructing high-resolution image are interpolated at first. Then, other zero -padding pixels are interpolated by using the bi-cubic method. By comparison with the results of nearest-neighborhood interpolation, bi-linear interpolation and the traditional bi-cubic interpolation, the result of this experiment on Lena image shows that the image edges are better persevered.

Abstract:OptiFDTD and Fast Fourier Transform method are used to simulate and analyze the diffracted field of transmission sub-wavelength binary gratings (TSBG). And the influence of grating parameters on the diffraction efficiency is numerically analyzed. The analysis result demonstrates that, for TSBG, the normal incident TE mode beam can be diffracted to the +1st order, the interval number has few influence on diffracted angle, the performance of a TSBG is determined by the grating period, material index and interval number for a given wavelength.

Abstract:A new method of LDPC product encoding and decoding by using the LDPC codes as component code is proposed. On the one hand, a low bit error ratio is obtained compared to the BCH product codes using binary extended BCH codes as component code. On the other hand, long LDPC codes are formed with short LDPC codes in the form of product codes, lowering complexity of long LDPC codes encoding. The simulation result shows that at low SNR, the bit error ratio of LDPC product codes is lower than that of the BCH product codes, at high SNR, the bit error ratio of LDPC product codes is higher than that of the BCH product codes. The same result is obtained compared with the same long LDPC codes. So the LDPC product codes are effective at low SNR.

Abstract:Based on the conventional TOPSIS and in the light of the relative membership degree method, the calculation steps are given to solve the problem of multiple attribute decision- making with incomplete information on attribute weights. The key is the relative membership degree, which is obtained by means of the synthetically weighted distance. Then, the decision is made according to the relative membership degrees. By using this new method the difficulties that occur in ranking intervals in the traditional analysis methods are overcome. This shows that the relative membership degree method is better in selecting the best and ranking alternatives than the traditional TOPSIS method. Finally, practical calculations are given, which shows that the models are feasible and practical.

Abstract:Using RF magnetron sputtering method, 300nm La2/3-Pb1/3-MnO3 thin film has been epitaxially grown on (100) LaA103 single - crystal substrates. The structure and the magneto - electrical properties of the thin film are investigated using X ray diffractometer, super-conducting quantum interference device and DC four-probe method. The results exhibit that the thin film with (100) preferred orientation is of a pseudo - cubic perovskite structure and has the good single crystalline. When the Curie temperature is at 335K, nearby the Curie temperature, the magneto-electric properties indicate a transition from ferromagnetic to paramagnetic and exhibit a characteristic of spin glass state, which is due to strain effects. The magnetic rules of paramagnetic state and spin glass state as well as ferromagnetic state are illustrated. The electrical property indicates that the thin film has quite a distinctive magneto-resistance effect which is 23.4% nearby the Curie temperature when the magnetic field is 1T.