Abstract:According to the working principle of a certain aviation turboshaft engine starting process, a novel algorithm is proposed to estimate the 'steady-state fuel flow' of starting process by combining with test data of this engine and merging rotor dynamics and numerical simulation. Based on this algorithm, a new method is presented to establish a mathematical model of turboshaft engine starting process, and the corresponding computer program is prepared and the simulation results are compared with the engine test data. The results show that the numerical results given by the created mathematical model of starting process are of good agreement with test data. The proposed mathematical modeling method of the turboshaft engine starting process is of some versatility.

Abstract:To determine the parameters needed for calculation, the impact on the titanium plate edge from steel sphere is numerically simulated based on the data from test. Then, a kind of aero-engine compressor blade is taken for example，the impact damage on the blade from steel sphere is studied. During the study, the elastic plastic with kinematical hardening model is adopted and the ANSYS／LS-DYNA is used to simulate the maximum state of the blade in take-off and landing. In order to quantitatively describe the damage law, the relative kinetic energy is introduced. The effect on the impact damage from mass and relative speed is able to be reflected by the relatively kinetic energy. Besides, for the given blade, the relationships between the relatively kinetic energy and the damage depth/width are exponential and the critical damage energy of the blade is 6.6 J.

Abstract:Aimed at the problem of the sensitivity of design variables in the design of aircraft structures，this paper puts forward a global sensitivity analyzing strategy based on Sobol's method and support vector machine method, and analyzes the parameter sensitivity with Sobol method by taking damage tolerance design to the aircraft overall beam as example, the overall beam cross-section parameters as design variables，and respectively constructing the replacement models of stress intensity factor and structure weight with the application of support vector machine theory. The result shows that the conclusion obtained can provide a guidance for selecting the design parameters and modifying the design variables in the optimization design of the structure.

Abstract:Based on three-dimensional Euler equation, a model of a certain three -stages compressor is established and calculated by adopting a method of body force. This paper mainly analyzes the effect of inlet guide vanes (IGV) on inlet distortion and the relation between IGV's angle and total pressure distortion in operation at the designed rotating speed. The result shows that IGV can improve the flow field and reduce the distortion parameter. The distortion range and the intensity are respectively reduced by 21.4% and 10.2% at the three stage rotor entrance. IGV has a favorable ability of rectification and anti-distortion. With the rise of IGV's angle, the distortion intensity gets lower, but it will come to increase while the IGV's angle reaches a certain value. Meanwhile, IGV will do the best with 45° .

Abstract:In order to suppress the influence from the outliers in the peak envelop extracted by peak detector, an azimuth estimation algorithm is proposed. The Huber function based on maximum likelihood criterion is utilized to suppress the error exceeding threshold and decrease the outliers' weight in the algorithm. Furthermore, double thresholds are adopted to improve Huber function, eliminate the bigger outliers' weight, compress the smaller weight and provide a basis for selecting the threshold parameters. This method does not need the statistics of noise, and can effectively suppress the influence of the outliers. Simulation results show that the accuracy of bearing parameter adopted by this algorithm is better than that of the ordinary Huber estimator and the least square algorithm. Under condition of the power SNR of 3 dB, the estimation error is less than 0.5° which meets the requirements of TACAN system .

Abstract:An underwater weapon will undergo stronger impact when it is in the incipient transient process of the entry-water, and this will cause serious harm to its structures and the carried instruments. It is very important to increase the reliability of the underwater weapon through researching the water entry impact of underwater weapon. In this paper, the numerical simulation of the vertical water-entry with zero attack angle at low speed for a missile is carried out based on the commercial software Fluent. The numerical simulation method of the water-entry at low speed for a column missile model is established using the technologies of dynamic mesh and UDF, and is validated by the experimental picture. The result shows that the numerical simulation accords with experimental results preferably at low speed for a missile with laminar flow model, however, the numerical simulation of the turbulence model shows an obvious error. So, the suitable method for low speed water-entry is not the turbulence model but the laminar flow model.

Abstract:In the squint airborne radars, the range dependence of clutter spectrum degrades the performance of conventional space time adaptive processing for clutter suppression, so a new method is proposed. In this method the similarity measure value is obtained by using the spatial domain steering vector relationship between the range bin under test and under test range bins. The received data of adjacent range bins is weighted by these values.In order to improve the detection performance of airborne radar, the non-homogeneity detector (NHD) is used to mitigate these interferences, and then the conventional STAP is applied to the clutter suppression. Finally,simulation results show that the new method is effective and practical.

Abstract:In order to study target assignment problems of multi-ground-to-air-missile-weapon-system to multi-aggressive-target, the factor of overlapping shooting-area is considered, wreathe status's changes of different shooting-areas to different aggressive targets are analyzed, and the target assignment progress is also fractionized. The best assignment method is found out through shooting-value's comparison between sub-zones. On the basis of the above,a genetic algorithm based on predatory search strategy (PSGA) is designed. The simulation results shows that the model and the algorithm are feasible.

Abstract:The uncertainty in air attack is one of the important factors interfering with the disposition of area air-defense operation, and every situation of air attack corresponds with one optimum disposition scheme. In order to synthesize the optimum schemes under conditions of every air-combat, this paper transforms the uncertainty of air attack into a multi-object decision problem by analysis, proposes the superiority and E-V criterion, and a method of optimum selection for disposition schemes based on risk decision. The result indicates that the method is simple in model designis, for calculating, and suitable for quick decision-making in disposing troops for battle.

Abstract:For the tracking of maneuvering targets under complicated air-battle environment, an adaptive filter data fusion algorithm for netted radar tracking is presented. First, according to a certain rule, the algorithm is used to find the best weights to make the fusion estimate an optimal goal. Secondly, the point is put into adaptive filter as an input signal. The interest related new adaptive filtering algorithm is used for the error change in the state equation and measurement equation to adjust the size of the gain matrix. According to the adaptive filter system state noise output signal and the current data, weights for radars are adjusted on line by using fuzzy logic system. The system output is the adaptive data fusion target optimal state estimation. The results of simulation verify the superiority of the algorithm in precision and convergence speed and realize the adaptive tracking for the target of netted radar system.

Abstract:A method, based on ultra-wideband technologies, is designed to quickly measure the phase-shifting steps of phased-array antenna element which is inconvenient to demount. By coupling and feeding UWB signals in picoseconds to antenna elements, phase-shifting steps of antenna element can be tested according to sampling echo signals. The use of data processing algorithms, such as window function method, greatly improves the accuracy of the test. A time domain measurement system of UWB used for testing phase-shifting steps of some phased-array antenna element is set up. The simulation is good in agreement with practice, and demonstrates the feasibility of the method in engineering practice.

Abstract:Current situation of single image defogging method are introduced,some classic algorithms based on image enhancement and image restoration are analyzed in detail,and advantages and disadvantages are listed in this paper.Comprehensive evaluation results show that the image restoration method is superior to the image enhancement method in the aspect of defogging. Aimed at the existing image restoration defogging method, thorough investigation and study are needed, and some problems about how to break through key technologies in defogging are analyzed from the establishment of a comprehensive physical model, the exploration of a prior knowledge of the model solution, the design of model solution methods based on human visual mechanism, and the evaluation of image defogging quality and some other aspects, etc.. Finally, the development trend of the existing technology is analyzed, and the orientation of studying defogging technology is given.

Abstract:Application virtualization is a key technology to support the software as a service. This paper analyzes and gives out the definition of application virtualization, discusses the advantages and research status of applicatio virtualization, and points out that the current application virtualization research is mainly centred on implementation issues, but negligent of the service quality of application virtualization. From the angle of platform dependence and distributed architecture, the application virtualization can be divided into homogeneous or heterogeneous application virtualization and local or remote application virtualization. And the paper analyzes the different types of application virtualization implementation principles in detail as well as the corresponding typical application virtualization software and their characteristics. Subsequently, the paper approaches the service quality evaluation method of application virtualization from the perspective of evaluation indicators and evaluation methods. Finally, aimed at the challenges faced by the service quality of application virtualization, the paper presents the research trends in application virtualization.

Abstract:This paper begins with the analysis of the protection range of lightning rod and lightning current, focusing on the discussion of the metal wire frame around the down lead, formed with wires of communication stations and the grounding system. The calculating result shows that the greater the lightning peak value, the shorter the wave front time, the nearer the metal wire frame with the lightning spot and the more likely the electrical device is compromised. If the metal wire frame works as the common ground of the lightning proof, the protection, working circuit, and the ground potential of the common ground fail to be equal everywhere due to the high voltage induction such as lightning with the fluctuations of voltage ranging from hundreds to thousands of volts, undermining electrical devices in the communication stations, especially the disruption of logic integrated circuit, the crash of CPU and hardware damage. The conclusion shows that the quantitative analysis of the paper provides a reference basis for the design of the thunder prevention of communication stations.

Abstract:The communication problem of weak and variable signal in troposcatter channel can be effectively solved using MIMO-OFDM technology. This paper analyzes the troposcatter channel characteristics and builds a scattering channel model. Then based on the MIMO-OFDM system model, combined with the actual situation, the parameters are selected and the experimental platform of the MIMO-OFDM system in scattering channel is established. And then under the promise of verification of performance of MIMO-OFDM system, the different transmission rate and different modulation system performance in the same scattering channel are simulated and analyzed. The simulation results show that, the communication capacity increase brought by MIMO-OFDM is obvious and on the premise of meeting the BER requirements, it can realize high speed scattering communication. And they also show than in the high speed transmission, 64QAM modulation is more conductive to reduce BER in scatter communication, meanwhile BPSK, QPSK and 16QAM modulation have little difference. The simulation provides a way for design and optimization of scattering equipment, which has multi rare and multi modem. It provides direction for the realization of large capacity and high reliability scattering communication.

Abstract:In view of the problem that the useful classification information in principal component analysis （PCA）may be lost in the process of network fault feature extraction,a new method named center distance ration weighted principal component analysis（CDRWPCA）. According to sample category information, the center distance ratio of the difference between characteristics is measured by using this algorithm. By doing so, the weight is designed based on the feature discrimination. Then the weighted datasets are used for PCA feature extraction. Finally, the extracted datasets are sent to support vector machines （SVM）so as to verify the effectiveness of the algorithm. Experiments on network fault diagnosis demonstrate that the the proposed algorithm can improve the compression ratio and the final fault recognition rate.

Abstract:In order to study the influence of meteorological elements on the guidance precision of missile under non-standard weather conditions, a type of combined guidance law applied to three-dimensional space is presented and a model of the combined guidance trajectory is established under non-standard weather conditions. An easy-to-program numerical solution of the basic equations of atmospheric motion is put forward and solved through numerical integral method of variable-step four orders Runge-Kutta combining the related differential equations. By way of contrast with proportional guidance trajectory under the standard atmosphere, the result shows that the combined guidance trajectory is closer to actual missile's trajectory.Which directly and vividly exhibits the motion trajectory demonstrating the situation in flying and hitting the target.by STK.

Abstract:In order to study the dynamic mechanical response of biotite granite，the dynamic compression and tensile tests to biotite granite sample are implemented by the SHPB experimental device system. The dynamic compression and tensile mechanical properties are investigated. Experimental results indicate that the dynamic compressive strength increases with impact speed increasing, and reaches to 347.1 MPa when impact speed arrives at 15.0 m/s.The dynamic compressive fracture form changes from mass to powder failure when the impact speed increases. Compared with static tensile strength, the dynamic tensile strength increases significantly.

Abstract:Aiming at the safety analysis of complicated business process, its pervasion mechanism is expounded both from structure and evolvement. The course of its transfer, accumulation and release is depicted with frequency and penetrability of safety risk network node,which are caculated by maximun entropy model and grey relation entropy model. Finally, an applied case of flight line maintenance process is provided to illustrate the feasibility crisp path based on ant algorithm, and to verify the efficiency to find the process crisp nodes which become the proofs for the availability of process risk management.

Abstract:In view of the problem that the performance of the traditional corner reflector is strongly dependent on the incident wavelength which makes it difficult to avoid the detection of frequency conversion radar, this paper designs a new corner reflector loaded with meta-material wave-absorbing layer, which creates approximately the same backward radar cross sections respectively at frequency points of 8 GHz ,11.5 GHz and 12 GHz. The test on the performance of the corner reflector shows that after the loading meta-materials absorbing layer is processed, the RCS value is decreased by about 2 dBsm at 11.5 GHz and decreased by about 3.6 dBsm at 12 GHz, and its RCS curve and the value of the common corner reflector are almost the same at 8 GHz. With no significant difference between the RCS curves of two frequency points, the performance of the new corner reflector meets the design requirements, thus providing a new approach for the countermeasure against the detection and identification of frequency conversion radar which works at the X band wave (8~12 GHz) to the corner reflector false target.