Abstract:In order to acquire an accurate aero-engine stability response model against airflow inlet distortion, the following steps are taken.Analyzing the stable total-pressure aberrance and turbulence distribution produced by the inserted-board airflow inlet distortion of a turbofan engine.Transforming the stable total pressure distortion and section pulse pressure into pressure-exciting waves at a set of frequencies.Through frequency spectrum analysis, the lowest steady pressure distortion waves' frequency and the biggest amplitude value are obtained, which are of the crucial factor that makes the engine lose its stability.Modifying the waves with a one-class response model and a parallel compressor model, a modified surging boundary is obtained.Calculating the high and low compressors' shifting process of operating points respectively when the engine is stalling gradually;Comparing the calculated result with that of the engine's experimental data, it is found that the results are similar.

Abstract:In order to improve the transportation efficiency and saving transportation cost of aviation fuel, a multi-restriction model-based optimization dispatch method is proposed. On the basis of analyzing the aviation fuel transportation pattern and the basic transportation principles, a simplification of the transportation problem is done. Again based on the related theory of network optimization and transportation problem, a multi-restriction model is established and the mathematical description of reliability restriction, cost restriction, time restriction and transport-capacity restriction is performed, then the algorithm and the solution steps based on multi-restriction are given. An example analysis of the established model is done by using the Dijkstra algorithm and work on table method. The results show that this model is accurate and effective in solving the problem of transportation optimization.

Abstract:The new intensified combustion technology by using non-thermal equilibrium plasma in aero propulsion field causes more and more attention. Aimed at the study of the effect of plasma assisted combustion, the combustion characteristics of methane/air with active particle (O and H) and active group (OH) in non-thermal equilibrium plasma in firebox is investigated by numerical analysis. The result shows that plasma assisted combustion can greatly enhance flaming temperature by providing more free radicals and accelerating chain reaction, meliorate the temperature distributions and velocity distributions of the surface of outlet. By this plasma assisted combustion technique, the combustion efficiency can be increased and the discharge of pollutant decreased.

Abstract:Aimed at the complicated structure and remarkable rigidity of its process, a method of hierarchical division optimization of flight line maintenance value stream based on GA and DSM is proposed. The value flow transferring model is built on the actual condition. According to its character of time-delay and propagation, an decoupling clustering method to improve the effect of value flow transferring is deduced. Then, its particular steps are given. The projection relationship between DSM model and cluster of value activities is defined. Futhermore, fitness function based on cluster weight, cluster scale, cluster number and decoupling parameter are designed. Therefore, The algorithm of value activities cluster based on GA and clustered activities decoupling decoupling. Finally, combining with case study of a military airfield. the validity of the model is proved, and the optimization pattern of flight line maintenance value stream is established.

Abstract:A serious vibration will happen when a brake experiment upon the aircraft wheel is done on the test-bed. The serious breakages will appear on both the module of aircraft wheel and the brake device. To solve the problem of the aircraft wheel vibration, the research on the aircraft wheel is conducted and a mechanical model of the brake vibration system is established. Based on the software of ABAQUS, the vibration process is simulated, and the natural frequency of the aircraft wheel is picked up. The comparison between the result of the simulation and that of the experimentation shows that the resonance appeared in the aircraft wheel test system is the cause of the serious vibration. Based on this, the optimization designs such as changing the number of grooves and increasing the number of gaskets, etc., are proposed. By adopting these measures, the vibration's impressing is diminished, the brake moment waving lessened and the vibration of aircraft wheel is reduced. At the same time, the frequencies of the force on the still tray and the system are changed. Thus the natural frequency of the aircraft wheel is avoided and the sympathetic vibration in aircraft wheel test system is averted, which make the reduction in vibrating acceleration of the wheel cylinder block as great as a factor of 8 times and that in displacement as great as a factor of 6 times. The application of these measures have weakened the vibration and enhanced the service life of the airplane wheel.

Abstract:This paper firstly analyzes the principle of the interaction of the plasma and supersonic flow and then establishes a mathematic model of the plasma on the basis of the main factors affecting the interaction. The simulation of interaction of plasma and supersonic flow has been performed and tested by experiment. The results of the study show that the plasma actuation reduces the shock wave intensity and proves the energy mechanism of interaction to be proper. The numerical simulation of shock wave intensity alteration with different plasma positions, different plasma groups and different plasma temperatures has been performed. The results show that: shock wave intensity reduces with plasma position moving ahead and plasma groups increasing; there is a threshold of the temperature of plasma which could make the flow throttling. The changes of shock wave intensity become inconspicuous because 2000k has already exceeded the threshold.

Abstract:Aimed at uncertain factors and dynamic characteristics of evaluation process, a static effectiveness evaluation method of aviation material support is put forward by establishing the pairs of effectiveness evaluation index of every unit and utilizing the Set Pair Analysis(SPA) theory that has the characteristics of ensuring same different and opposite of unsure system rational depict on certain speciality. Again a dynamic effectiveness evaluation method is proposed by utilizing the Markov chain to analyze the effectiveness evaluation change rules of aviation material support for certain unit. and then, put forwarded the dynamic effectiveness evaluation method. Example calculation shows that the synthesis SPA method can provide scientific basis for the decision maker in making the strategy of aviation material support.

Abstract:Aimed at the incorporating ballistic missile defense problem, a design method of Engage Schedule Group is put forward, by using which the auto-engage can be implemented effectively according to schedule for ballistic missile defense. Based on the incorporating ballistic missile defense system architecture, the conception of Engage Schedule Group (ESG) for ballistic missile defense is set up. Then the ESGs for ballistic missile boost phase, midcourse phase, and terminal phase intercepting are designed, which are capable of intercepting ballistic missiles in all phases of their flight trajectory. Finally, the information schedules of these ESGs are programmed. The design of ESG is of great value to the plan for and the integration of a ballistic missile defense system and its application.

Abstract:This paper researches the problems of coordination firepower deployment of multi-layered BMD system. Firstly, the concept of multi-layered BMD system is defined, and anti-missile platforms of multi-layered BMD system are introduced. Secondly, the basic requirements of the firepower deployment of multi-layered BMD system are analyzed. Thirdly, since the anti-missile operation is an offence and defense process, this paper establishes a min-max model of coordination firepower deployment of multi-layered BMD system based on Game Theory, and again presents an algorithm to solve the model. Finally, by a calculation example and simulation, the optimal coordination deployment plan is gained. The model and the results can provide a reference for the improvement of the operation efficiency.

Abstract:In the course of pulsed eddy current testing, the incline of the probe or the roughness of the surface of the tested object will lead to the lift-off effects, which have a bad influence on the result of pulsed eddy current (PEC) nondestructive testing. Based on the analysis of the operating principle of PEC, two different simulation models with the excitation coils of columniform and rectangle structures are established by ANSYS finite element simulation software and the simulations on the specimen of ferromagnetic and non-ferromagnetic materials are done respectively. Through the analysis of the eddy current and rotated magnetic field, the influence effect of response signal with the variation of the lift-off distance and the reason is given. Finally, the results of simulation are verified by experiment methods. The results of the experimental work confirm the correctness of simulation, which will lay the foundation for the elimination of lift-off effects.

Abstract:In view of the problem that the time taken in test calibration is longer which results in low efficiency in phase shifter of microwave landing system land equipment (MLE) fault diagnosis, based on the calibration principium of phase array antenna, scanning antenna array parameter obtaining method and phase shifter fault diagnosis flow are analyzed. Optimum phase for every antenna array is calculated with phase-only shaping of amplitude pattern algorithm, which modulates factors of close equation with measuring radiation power and calculates the optimum phase with former quantization error added in, so that array parameters are calculated through a small quantity of iteration, and calibration time is shortened. Consequently, phase shifter fault is diagnosed quickly with array parameters after test calibration compared with the array parameters deposited in RAM of antenna controller after task calibration. Finally, the feasibility of this method is verified through computing simulation.

Abstract:On-board switching is one of the key technologies of spatial information network. The paper analyzes the designs of foreign and domestic researchers, summarizes the evolved researches including the design of switch fabric and CAC，cache management algorithms. Based on these studies, the on-board switching technology based on ATM development direction is presented.

Abstract:In on-board regeneration satellite communications, the burden of satellite transponder is light when on-board processor works without channel decoding and recoding, but LDPC performance degradation will occur because the bit posteriori probability can not estimated precisely in LDPC classic MP algorithm. This paper researches on the algorithm of estimating the posteriori probability precisely in the downlink. Firstly a satellite communication model is constructed and the kernel of posteriori probability estimation puzzles is analyzed, then an advanced posteriori probability estimation algorithm is derived by means of probability theory. The matlab simulation displays 0.7 dB gain of the enhanced algorithm when the SNR in the uplink and that in the downlink are equivalent, and the bit error probability is 10-5. In the regeneration satellite communication system without on-board decoding and recoding, the advanced algorithm can be used to improve the performance of the receiver.

Abstract:This paper presents a MANET routing model based on chord, expands P2P distributed share strategy into MANET Routing. By using the new model a structured P2P network overlay is formed on MANET physical network, the Chord algorithm is combined with DSR protocol, thus the storage and computational resources of free nodes are exploited fully to speed up the routing process, which makes nodes acquire more available routing information. The experiment proves that the use of this model can availably increase the large-scale MANET routing efficiency, which lays the foundations for exploiting the efficient and available MANET routing protocols.

Abstract:Based on the problem of considering the link cost into delay constraint, this paper proposes a new delay constrained minimum cost path algorithm (DCMC) which is used for searching the shortest path between nodes. On this basis, an efficient center node selection method is further modified based on the cost-delay ratio (CDR). Based on application of CBT a center selection for delay constrained minimum cost multicast routing (CS_DCMCMR) algorithm is proposed by using the above two algorithms. In the use of this algorithm, both cost and delay are taken into consideration simultaneously in path search and central node selection. The simulation results show that the time complexity of CS_DCMCMR algorithm is O(mlogn), compared with CSDVC and CCLDA algorithms, the use of this algorithm can largely reduce the total cost of the final multicast tree in the case of meeting delay and delay variation constraints without the increase of complexity.

Abstract:Platform position maintaining is a major challenge for the airship or aircraft based High Altitude Platform (HAP) communication systems. The platform maintaining a stationary position will introduce a high price. Hence, a position cylinder is suggested for the position maintaining of the platform. This paper derives the computation formula for the maximum distance of the HAP horizontal displacement when a fixed pointing antenna is adopted at the terminal, and simultaneously the handover probability in a cellular of the service area under limited and un-limited average call durations is analyzed. The study results show that the maximum distance for the HAP horizontal displacement increases with the user beam-width. Under the condition of the same beam-width, the higher the altitude of the platform, and the smaller the maximum distance for the platform displacement is required. Moreover, the horizontal displacement can only generate handover in the area near the edge of the cellular. The calls which are nearer to the cell edge have higher handover probability. The average handover probability increases with the maximum distance for the HAP displacement. The larger the HAP displacement during the call duration, the greater the average handover probability is. When the call duration time and the platform speed tend to infinite, the handover probability reaches to the maximum value.

Abstract:The paper has established the models of the plat leaf shapes by using space curve theory. Different types of leaf shapes can be obtained by adjusting the parameters, and with the increase of leaf outline length parameters, leaves can grow. First, according to the characteristics of leaves, the curvature and torsion functions of the edge line can be determined, then the outlines of half leaves are drawn by solving the basic equations of space curves, and the other half edge of line is drawn according to the symmetry of the leaves. The curves of the main venations can be determined by using projection method and affine transformation. Loop subdivisions have been used to obtain smooth leaves. In the situation that the curvature functions are piecewise power functions, the growths of two-dimensional leaf blades are always along the axils of initial directions have been demonstrated. Using the method mentioned in this paper can draw out complex leaves. The simulation experiment results verify the feasibility of the proposed method.

Abstract:The differential evolution algorithm is robust, easy to use, and requires few control parameters. However, as to the local optimizing ability, it is limited. Based on the principium analysis of the algorithm, the adaptive modification of the cross rate and the cross operator is proposed to improve the efficiency of the algorithm. To enhance the local optimizing, the local enhanced operator and the disturbed operator are proposed. Numerical study is carried out using five benchmark functions. Compared with the PSO algorithm, DE and MPDE, the ADMPDE is the most efficient algorithm of all, which verifies that the modification is effective.

Abstract:Based on the erbium-doped fiber Giles' model, a numerical model of an erbium-doped fiber ring laser is established and stimulation parameters are set according to the actual used σ structure, which are used to simulate the impacts of forward Amplified Spontaneous Emission (ASE), backward ASE and two-way ASE on the performance of laser, and to obtain the optimum parameters of laser. Stimulation results show that when the laser oscillates, the consideration of the direction of ASE has little influence on the output optical power amplitude or Giles gain particles distribution, while the existence of backward ASE results in the cut-off length of erbium-doped fiber. The comparison between the experiment and the simulation indicates that this model can describe the performance of laser precisely, so that it can be used to optimize the actual laser design.