Abstract:Abstract:Aimed at the problems that the information between the sensors and the controller is transmitted in the form of multiplepacket in aeroengine distributed control system (DCS), the sensor nodes encapsulate the data measured into several data packets to transmit to the controller, at each sampling time, and a part of the data packets could be sent while the data packets failed to send would be discarded, in view of the mentionedabove conditions, a neural network predictor is designed to update the packets failed to be transmitted by a predicted value, making the aeroengine DCS with multiplepacket transmission an aeroengine DCS with singlepacket transmission. And then a multiplepacket transmission DCS model based on state estimation is established, and an observer is constructed. The observer error system could be regarded as a discrete periodic system, and the periodic system stability theory is utilized for deriving the stable working conditions of the neural network predictor and fault observer. Finally, the specific fault detection steps are given, and the simulation results show that the proposed fault detection method is valid.

Abstract:To investigate the residual tensile stress formation mechanism of thinwalled piece in laser shock peening, the shock wave propagation law and the dynamic respond law of 0.5mm titanium alloy thinwalled piece are analyzed by ABAQUS software. The results show that when in reflecting in the thinwalled piece, the shock wave forms highintensity tensile wave and compression wave in turn. The stress distribution in depth is disordered under the action of tensile wave and compression wave, and is characterized by multiple peaks. The tensile stress field is located within 0.125mm beneath the surface and the residual tensile stress up to 426 MPa appears on the surface. The formation mechanism of residual tensile stress is revealed based on the shock wave reflection law. The maximum residual tensile stress is only 70 MPa in the 5mm thick plate and tensile stress at the surface translates into compressive stress by reducing the intensity of reflected tensile wave. Therefore, based on the principle of controlling the reflection wave pressure, a method of stress field regulation by exporting shock wave is proposed.

Abstract:As for the fault diagnosis of gear at early stage, the conventional methods of signal processing are significantly interfered by noise, blocking the fault feature extraction of gear. This paper proposes a PSO sparse decomposition combined with PSO (Particle swarm optimization) algorithm and sparse decomposition algorithm, lowering the computing complexity of sparse decomposition, and also proposes a ‘Matching index’ as the signal feature. The research result of the simulated signal indicates that PSO decomposition performs well under condition of strong noise and improves the SNR greatly. What’s more, the PSO sparse decomposition is proved efficiently in fault signal feature extraction of gear through the analysis of the signal from aeroengine gear hub. The ‘Matching index’ of fault signal is 04 higher equally than that of normal signal. This is superior obviously to the traditional methods.

Abstract:Aimed at the problem that the existing track clustering algorithm does not take into account the influence of aircraft heading change and altitude drop on the clustering results, at the same time, the clustering process lacks time information, and in addition, outlier data exist in the two radar data, and the existence of outliers will affect the final clustering result, leading to inaccurate clustering results, this paper proposes a time window segmentation algorithm based on feature point track. The algorithm is to take the aircraft heading change approach value and height decreased value as the influence factors of determining cluster size, the paper segments the number of aircraft entering the track point time window segmentation. The simulation analysis of real approach two radar data shows that when the influence factor is 0.4, the curvature of track is minimum, and the clustering effect is the best, then the hierarchical clustering algorithm is used to cluster the tracks corresponding to different values, and the final clustering results are obtained, providing technical guidance for the controller's scene command.

Abstract:Aimed at the problems that aerodynamic noise of specific airframe is often neglected in predicting the flight noise level of aircraft during taking off and landing by the data of ground check, this paper analyzes the airport noise and puts forward a method to predict aerodynamic noise of specific airframe by using FfowcsWilliams & Hawkings acoustic model. Taking the A380 aircraft as an example, simulated and analyzed by Ansys Fluent, the streamline of flow field and sound pressure intensity are obtained. The results show that the airframe noise is a broadband noise, the vortex intensity and pressure fluctuation are mainly concentrated in the ventral wing and aircraft’s underside, increasing gradually from root to tip and reaching the maximum value in the tip region, this phenomenon causes the synthetic sound pressure level which is below the plane is much higher than that on the any other directions.

Abstract:The sortie generation rate of military aircraft is a significant parameter to evaluate the dispatched ability. This article, taking the coefficient of utilization and the cost of support equipment as constraint conditions, and taking the aircraft sortie generation rate as objective function, establishes a MonteCarlo queuing simulation model. The article utilizes the numerical values of objective function through MonteCarlo simulation, and then optimizes the configuration projections of support equipment in applying the genetic algorithm to satisfy the constraint conditions maximizing the sortie generation rate. The article analyzes the sensitivity of sortie generation rate of aircraft, and obtains a curve line about allocation proportion of support equipment of influencing on the sortie generation rate.

Abstract:Aimed at the problems that the shielding effects of conecylinder ballistic target exists in the process of observation, the concrete location of the boundary between the shielding area and the visible area can be made a thorough inquiry, and a novel algorithm is proposed to judge whether the scatter is shielded or not. First, a mathematic model of echo based on the observation in narrowband radar is built. Then, a model of sliding scatters of the cone cylinder ballistic target is built, and the characteristic of each scatter is analyzed. Finally, this paper looks into the causes of the shielding effects, analyzes the location of the boundary between the shielding area and the visible area, and proposes a novel algorithm to judge if the scatter is shielded. The simulation shows that the microDoppler curves of ideal scatters and sliding scaffers are different and shielding effects will result in the francation phenomenon of the microDoppler curves with the change of observation angles, which proves that the conclusion of this article is right and the algorithm is effective. And this provides a reference for the feature analysis of ballistic target being shielded.

Abstract:In this paper, the related research literature is combed, the principle and properties of frequency diverse array are analyzed and simulated, and the research status of beam control of frequency diverse array is emphasized. This paper analyzes three mechanisms of transmit and receive signal processing for frequency diverse array radar. For two mechanisms, linear constrained minimum variance (LCMV) norm is applied to the adaptive beam forming simulation analysis. Finally, a linear constrained minimum variance criterion algorithm based on variable load constraint is proposed. Based on the first processing mechanism of frequency array radar, narrowband filter is used to filter out only the signal of carrier frequencyfm in channelm. In order to reduce the amount of computation, an upper bound on the weight vector norm is set, and a weight vector and a steering vector are obtained by the steepest descent method. The simulation results show that the algorithm can form a large gain in the desired direction in the presence of 5°error, and the null in undesired direction. Compared with the adaptive algorithm under condition of the first processing mechanism, the time reduces by 27.3%.

Abstract:Absorptive chaff is a kind of light and highefficiency passive jamming material. Through making echo amplitude scattered heavily in the air received by enemy equipment in detecting fallen, this can reduce the probability of being found and tracked by radar equipment. This paper studies the jamming performance of absorptive chaff cloud on radar wave. First, combined the existing research results, the jamming mechanism of absorptive chaff cloud on radar wave is analyzed. Then, according to the transmissionline theory and energy conservation principles, models of reflection loss and transmission loss on the surface of absorber are built. Finally, a power attenuation model is built, and radar maximum range changes after interference is obtained. The simulation results show that the absorptive chaff cloud has obvious weak effect on radar wave. With 100 meters’ thickness, the attenuation can reach 23.4 dB. When attenuation is greater than 8.7 dB, the bandwidth can be 11 GHz, which is 64.7 percent of the entire bandwidth. Therefore, absorptive chaff cloud has obvious weaken effect on radar wave, and this has some value of application in the battleground.

Abstract:To reduce the computational complexity of the twodimensional direction of arrival (DOA) with planar array, this paper proposes a semirealvalued MUSIC algorithm. The paper transforms one of the DOA estimation into an estimation of the angles between the target andx axis andy axis. Firstly, the real part of the received signal covariance matrix is extracted and performed an eigendecomposition to obtain the noise subspace. Then, the dimension of the process is reduced to achieve one dimension semirealvalued MUSIC spectrum. Next, the paper evaluates the estimation of the angle between the incident direction and thex axis. After that the paper utilizes the leastsquare method for getting an estimation of the angle between the target andy axis. Finally according to the corresponding relationship between azimuth and elevation and the two angles, the twodimensional DOA estimate is evaluated. This algorithm has the similar estimation performance with traditional MUSIC algorithm, significantly reducing computation complexity. The simulation results show that the algorithm is valid.

Abstract:This paper proposes a design of ultrabroadband reflective polarization convension metasurface composed of the shape of “H” metallic periodic structure, a layer dielectric and a metallic plate ground. Almost an equal magnitude and a 90° phase difference generated between the two orthogonal electric components of the reflected waves can be reached by changing the size of the metasurface cell. The simulation and measurement show that this device can allow linear to convert circular polarization from 6.40 GHz to 15.40 GHz and 17.49 GHz to 18.14 GHz, while the axis ratio is less than 3 dB. This can also realize more than 80% polarization conversion ratio from 15.81 GHz to 17.26 GHz under bothxandypolarized incidence. The proposed polarization convension is characterized by a compact structure and simple geometry, a low loss to energy in ultrabroadband, using more unit cell in the available space. This design is of great value to electromagnetic control and design of new antennas.

Abstract:A novel planar ultrawide band (UWB) antenna based on complementary splitring resonator (CSRR) structure with bandnotched characteristics is proposed in the paper. The proposed antenna has a wide impedance matching characteristic with the gradual feeding line. By etching two splitring slots on the patch, the dual bandnotched characteristic is obtained. The fabricated antenna is tiny in size, only 35 mm×30 mm×1 mm. Simulation software HFSS 13.0 is used to analyze and optimize the structure parameters. The antenna is tested by physical measurement. The measured performance is of the same simulated results. The results show that the operating frequency band is within the range of 2.7~15.6 GHz, and the voltage standing wave ratio is lower than 2 (VSWR<2); when the operating frequency band is within the range of 3.1～3.7 GHz and 5.1～5.9 GHz, there are good bandnotched characteristics respectively in the bandwidth of WiMAX and WLAN. And there is a nearly directional radiation pattern and a stable gain. The antenna is compact and conformal, and can be applied to UWB communication system preferably.

Abstract:To realize the ejection of heavy projectile with smaller current, a seriesconnected augmented quadruple electromagnetic rail launcher is proposed based on quadruple rail launcher. The mathematics model of electromagnetic thrust generated by the main rails and auxiliary rails of augmented rail launcher is established respectively and the characteristics of electromagnetic thrust are simulated, and a formula of determining the number of rail plies according to preset thrust is given. The ejection process of traditional and augmented rail launcher was modeled and simulated. The results show that the electromagnetic thrust of augmented launcher approaches the maximum at a lower position and the rail current of augmented rail launcher is less than 60％ of the traditional rail launcher when ejecting the projectile to same speed.

Abstract:In order to detect frequency hopping signals in complex electromagnetic environment, this paper utilizes the approximate l0 norm algorithm for reconstructing the frequency hopping signal with interference according to the sparsity of frequency hopping signal in frequency domain. The unconstrained multidimensional optimization problem is solved by the quasi Newton method, and the paper utilizes the obtained timefrequency map as an image for performing two value morphological filtering to eliminate the interference and noise. Frequency hopping signal is detected by counting the number of matched signals. In view of improving the adaptability of the algorithm, this paper uses the Otsu method in selecting binarization threshold. The theoretical analysis and the simulation show that the algorithm not only can overcome the interference under low SNR condition but also can accomplish signal detection.

Abstract:This article analyzes the problems existed in the MMSE-RISIC algorithm in detail and proposes an improved MMSE-RISIC equalization algorithm for SCFDE whose frame structure applied Unique Word (UW). This algorithm adds a noise prediction module to utilize the correlation between the estimated noise in UW and the estimated noise in date. The noise in data after MMSE equalization is predicted and eliminated by the estimated noise in UW. The estimation accuracy of RISI will also improve. Finally, the parameters based on the 300 km troposcatter channel in north China are utilized for making a simulation. The results show that the improved MMSE-RISIC equalization can lower a bit of error rate (BER) under condition of low signal to noise ratio (SNR). And SNR gains about 2 dB when BER=10 -3 compared with the MMSERISIC equalization.

Abstract:Aimed at the problem that the local optimization is easily caught in and the convergence rate is slow, this paper proposes a hybrid algorithm of particle swarm optimization and simulated annealing based on intuitional fuzzy entropy (IFEPSO-SA) in solving largescale 0-1 knapsack problems by using intelligence algorithm. Exchange operation and simulated annealing mechanism are applied to the local secondary optimization. Then, a metric based on intuitional fuzzy entropy (IFE) of the population is used to change inertia weight adaptively, and particles make the mutation based on the metric. The testing result shows that IFEPSO-SA is good in solution quality in solving largescale 0-1 knapsack problems. And the simulation experiment results show that entropy fluctuation of IFEPSO-SA is comparatively stable compared with the intuitional fuzzy entropy based particle swarm optimization (IFEPSO), reflecting a yet higher local search ability. Meanwhile, IFEPSO-SA is superior to IFEPSO and classical particle swarm optimization and simulated annealing in terms of convergence speed and solution quality.

Abstract:Due to the introduction of N Bottom Assist Layer (NBAL), the superjunction structure of relatively small aspect ratio could be used in 4HSiC semisuperjunction vertical doublediffused metal oxide semiconductor field effect transistor (VDMOSFET), so that the cost and difficulty of manufacturing process could be reduced. In this paper, a twodimensional simulation structure of the device is established based on the device simulator Atlas. The single event burnout (SEB) effect of 4HSiC semi-super-junction VDMOSFET and 4H-SiC superjunction VDMOSFET are comparatively studied, then the influence of NBAL doping concentration on the antiSEB ability of 4H-SiC semi-super-junction VDMOSFET is studied. The results show that, under condition of the same drain voltage, the peak value of the electric field in the N- drift/N+ substrate junction of semisuperjunction VDMOSFET is 27％ lower than the counterpart of the superjunction VDMOSFET owing to the NBAL. The SEB threshold voltage (VSEB) of superjunction VDMOSFET is 920 V, while the counterpart of semi-super-junction VDMOSFET is 1 010 V, so that the anti-SEB capability of semi-super-junction VDMOSFET increases by 10％ when compared with super-junction VDMOSFET. With the gradual increasing of NBALdoping concentration, the anti-SEB ability of VDMOSFET is firstly enhanced and then weakened, i. e., there is an optimal doping concentration of NBAL to make the ability of the anti-SEB the strongest.

Abstract:In order to provide a calculation method for the design of the sandwich panel structure, a threedimensional finite element model of the sandwich panel structure of multilayer elastic foundation is adopted by ANSYS. At the same time, the finite element model is utilized for calculating the mechanical response of the aircraft used in the typical pavement structure. The results show that the type of face plate has little effect on the mechanical response, and the contact status between the pavement and the base course greatly affects on it. The contact coefficient increases from 0.01 to 10, and the deflection of the single and double plates decreases by 17.2% and 9.9% respectively. At the same time, the tensile stress under the base is reduced by 21.7% and 27.1%. This shows that the improvement of the contact status between the pavement and the base is fatal. Finally the bearing plate test and pass test are completed. The experimental results verify the correctness of the finite element model, and provide the analytical method for the similar pavement structures.

Abstract:This paper presents and realizes a digital filtering method for odometersignal based on state machine. The method, taking field programmable gate array as hardware，detects and filters burr of the odometer signal after resistanceCapacitance circuits and optical coupler, analyzes the causes of bring on metastable state when odometer signal is in fluctuation, gives out a design and implementation of filtering state machine and the method treating with the anomaly state caused by metastable state. The simulation results show that the method can filter out disturbance signal effectively and the counting number of odometer signal is accurate, and this is feasible in engineering.