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2010 Vol. 36, No. 1

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Microstructure and mechanical properties of hybrid pulse VPTIG arc welding of high strength aluminum alloy
Cong Baoqiang, Qi Bojin, Zhou Xingguo, Luo Jun
2010, 36(1): 1-5.
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The effect of ultrasonic pulse square wave current on 2219-T87 high strength aluminum alloy welds microstructure and mechanical properties was researched based on a novel ultrafast convert hybrid pulse variable polarity TIG arc welding technology. The experimental results show that the microstructure in the weld is predominantly columnar in the case of traditional variable polarity current. The grain structures in the weld zone become finer and more equiaxed with the effect of ultrasonic pulse current. Weld tensile strength and percentage elongation are obviously improved, respectively. Weld fracture type is changed from mostly brittle to the obvious mixture of dimple and brittle. The effect of hybrid pulse current is more effective with higher pulse frequency and lower pulse current duration in a certain range. The rates of weld tensile strength and percentage elongation to base metal are 70% and 58%, respectively, under a 40 kHz ultrasonic pulse current frequency and 20% pulse duty cycle.
Optimal Lambert transfer based on guiding artificial immune algorithm
Peng Kun, Xu Shijie, Chen Tong
2010, 36(1): 6-9.
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The optimization with cost function of fuel consumption minimum for Lambert two-impulse transfer was studied. Firstly, the universal variables method was modified to avoid singularity, and it was used to solve the Lambert two-impulse transfer problem. Then for the rendezvous problem with only orbit elements fixed of a chase spacecraft and a target spacecraft in initial time, the concept of phase time was introduced under the restriction of the total time. Both the phase time and transfer time were considered as variables to be optimized in the Lambert transfer. Finally, a guiding artificial immune algorithm (GAIA) was applied to solve this optimization problem. Simulation results show that, compared with adaptive genetic algorithm (AGA), GAIA has stronger search capacity and quicker search speed, which validates the effectiveness of GAIA for the optimal Lambert transfer.
On the performance of two shock-capturing schemes
Yu Jian, Yan Chao
2010, 36(1): 10-13.
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Two shock-capturing schemes were considered: characteristic-based MUSCL (monotone upstream-centred schemes for conservation laws) scheme and WENO (weighted essentially non-oscillatory) scheme. Local linearization was employed when performing characteristic transformation, and limiters were applied according to the characteristics of waves; A dimension by dimension reconstruction was used to obtain truly accurate finite volume WENO scheme. Numerical experiments were carried out on one-, two- and three-dimensional Euler systems. The results show with one- and two-dimensional examples that characteristic-based MUSCL scheme performs better on capturing contact discontinuities, and shows little difference from WENO scheme on shocks. For three-dimensional problems, a finer resolution of complex flow feature can be obtained by WENO scheme. Explanations as well as possible improvements are given.
Prognostics and health management system of hydraulic power supply
Zhao Sijun, Wang Shaoping, Shang Yaoxing
2010, 36(1): 14-17.
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With the requirement of high reliability and indemnificatory of on-board hydraulic power supply system, the general structure of prognostics and health management (PHM) of hydraulic power supply system based on its fault mechanism was presented, the function of every layer in PHM of hydraulic power supply was described, and the key technology of on-board PHM system and ground maintenance system was studied. Considering the rapid calculation requirement, the on-board PHM and ground database of maintenance based on digital signal processor was designed. Intelligent diagnosis algorithm and effective fault prognostics were realized. The correctness and validity of the structure of PHM of hydraulic power supply system were tested and verified though the experiments.
Design and simulation of power regulator based electro-hydrostatic actuator
Kang Rongjie, Chen Lisha, Jiao Zongxia
2010, 36(1): 18-21.
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The electro-hydrostatic actuator(EHA) is a kind of power-by-wire actuator that converts the electrical power into local hydraulic power which combines the benefits of conventional hydraulic system and direct drive electrical actuators. Compared to the servovalve controlled actuator, the efficiency and reliability of EHA are increased. However, the frequency width and stiffness are limited. A novel structure EHA with power regulator and hydraulic lock was proposed to overcome these problems. The power regulator managed the power distribution in EHA system according to different control requirements. The hydraulic lock helped to keep the output in desired position. Based on its mathematic equations, the optimization principle of power regulator was discussed and the control strategy was specifically designed for this EHA. The simulation results verify the improvements in response and frequency width.
Differential quadrature solutions for buckling of laminated beams with multiple arbitrary delaminations
Han Haitao, Zhang Zheng, Lu Zixing
2010, 36(1): 22-25.
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Based on Timoshenko beam theory, a multi-beam model was presented for buckling analysis of laminated beams with arbitrary multiple delaminations, using differential quadrature (DQ) method. Comparisons showed high consistent between the critical buckling loads of the model with a single delamination and those coming from relative references. The investigations of the clamped beams were made to reveal the influences of the length, the depth and the positions of the delaminations on buckling loads. The configuration including a beam with two across-the-width delaminations with arbitrary lengths and located at arbitrary depths was studied. DQ method provides a simple and effective method for the buckling analysis of laminated beams with arbitrary multiple across-the-width delaminations, and provides some valuable results for design of laminated structures.
Tension control strategy for TSS retrieval process based on backstepping control method
Zhong Rui, Xu Shijie
2010, 36(1): 26-30.
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A new tension control law based on backstepping control method was proposed for planar retrieval control of tethered satellite system(TSS). The control law was designed in two steps. Firstly, the planar swing angle was stabilized into target value via using backstepping control method. Then, the retrieval velocity was controlled by designing appropriate profile for the target value. A continuous piecewise profile was adopted for the target value and a delay term was added to ensure a better retrieval behavior. Numerical simulation results validate that the control law designed here works well for TSS mission in circular, near circular orbits and also elliptical orbit with large eccentricity.
Dynamic source identification of emitting characters in enclosed environments
Chang Haijuan, Pang Liping, Qu Hongquan, Wang Jun
2010, 36(1): 31-34.
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Along with the prolonging of people-s staying time in enclosed environments such as spacecraft, aircraft, submarine and so on, air pollution in the cabin has become a main factor which endangers missionaries- life safety. To improve the ability of these enclosed environments in dealing with sudden contaminant, a novel discrete concentration stochastic model was established. The sensitivity analysis algorithm which can identify source location and strength was presented. Then the dynamic identification of source emitting characters and prediction of contaminant concentration were realized using combined implicit and explicit Kalman filter. The identifiable zone of different sensor placements was analyzed, and the best scheme of sensor placement had been found. Simulation results prove that the sensitivity analysis algorithm and combined implicit and explicit Kalman filter can realize the dynamic identification of source emitting characters and prediction of contaminant concentration speedily and accurately.
Algorithm for waypoints re-planning of reconnaissance unmanned aerial vehicles
Zhang Yani, Gao Jinyuan
2010, 36(1): 35-38.
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An on-line waypoints re-planner was presented .It is capable of adjusting trajectory when some targets are detected. A mathematics model of multi-objective optimization under multi-constraint for re-planning was built. Advanced NSGA-II was adopted to find the Pareto non-dominant route set, aiming at maximizing weighted image quality of each target and minimizing route length under constraints. By using the general image quality equation(GIQE), image quality of each target was forecasted. Constraints were determined by field-of-regard(FOR) of sensor, dynamic motion of the vehicle, image quality demand, safety distance etc. Fuzzy selection was applied to select the optimal route from the Pareto non-dominant route set refer to current weights of weighted image quality, route length and risk given by expert system. The simulated result showed the rationality and intelligence of the method.
Dynamic path searching method for ATE switch matrix
Wang Guohua, Yang Zhongliang, Chen Niya
2010, 36(1): 39-42.
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Due to the imbalance use of switches, some switches of switch matrix in ATE (automatic test equipment) fault early while others not. Switches fault destroys the topology of switch matrix and makes path searching more complicatedly. To achieve switch load equalization and path searching with a complicated matrix topology, the path matrix, the switch state matrix and the reachability matrix were defined to unify the mathematic model of switch matrix. And then a path searching algorithm based on reachability matrix was proposed. The switch reliability and path reliability were defined, a path selection method based on path reliability was proposed to resolve the imbalance use problem of switches. An example based on an open fault switch matrix shows that this method can be competent for path searching while the switch matrix is fault, and the path selection is optimized which can help promoting the switch matrix life.
Effects of dynamic load on flow resistance, void fraction and heat transfer of steam-water two-phase flow in pipes
Yao Qiuping, Song Baoyin, Zhao Mei
2010, 36(1): 43-47.
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An experimental investigation using a rotating platform was performed to obtain the flow and heat transfer characteristics of single-phase water and two-phase pipe boiling water under dynamic load in present work. By changing the parameters, such as rotation speed, inlet temperature, flow rate, and so on, the flow and heat transfer data of single-phase water and two-phase boiling water flow under static and dynamic conditions were obtained. The image of two-phase flow patterns under dynamic load was obtained with a video camera. The results show that as the direction of the dynamic load is opposite to the flow direction, the greater the dynamic load, the higher the outlet pressure in test section and the flow resistance, and the lower the liquid flow rate, the void fraction, and the heat gained by fluid. Therefore, the dynamic load will block the fluid flow, enhance heat dissipation toward the ambient environment and reduce the heat transfer to the two-phase boiling fluid.
Spacecraft attitude maneuver planning based on particle swarm optimization
Yang Siliang, Xu Shijie
2010, 36(1): 48-51.
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For spacecraft suffering from multiple celestial constraints in time-varying space enviroment, an on-board large angle attitude maneuver path planning based on particle swarm optimization was studied. The kinematics of the spacecraft was described by Rodrigues parameter. The full attitude was mapped to a point described in three-dimensional attitude space. Then the attitude path planning was transformed to the problem of three dimension path planning for point robots. The large angle attitude maneuver path planning algorithm based on particle swarm optimization for spacecraft with multiple celestial constraints was designed. It is necessary to change the attitude coordinate from the original reference frame to a proper reference frame which is more convenient in calculation for the path planning algorithm. Through the iterative program we can receive the feasible path. Numerical simulation results demonstrate the validity of the method.
Numerical simulation on flow induced by plasma actuator based on phenomenological model
ZHANG Pan-Feng, LIU Ai-Bing, WANG Jin-Jun
2010, 36(1): 52-56.
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The flow induced by plasma actuator in two dimensional incompressible flow was simulated based on a phenomenological model, which was realized by adding the body force source term to the Navier-Stokes equations. The numerical results present that there is a wall jet formed downstream of the plasma actuator. The velocity profiles at different streamwise stations, the variation of the maximum velocity and the width variation of the wall jet are quit similar to the traditional laminar jet(wall jet or two dimensional slot jet), which indicates that the effect of the plasma actuator on the ambient neutral flow can be regarded as potential flow interaction. At last, the blowing momentum coefficient of the wall jet induced by the plasma actuator was obtained by integration, which was negligible compared with that of the traditional blowing flow control method. So the plasma actuator flow control method just can be applied in low speed flow at present.
Unclosed loop subdivision wavelets transform based on boundary preserving
Zhao Gang, Bai Jie, Ji Baopeng, Yu Jiaqing
2010, 36(1): 57-60.
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A loop subdivision wavelet transform algorithm for the unclosed mesh surface was presented. Using the plane on which the mesh boundary located as the reflection mirror, the unclosed mesh can be mirrored as a closed one with the symmetrical structure. In this case, the boundary points of the original mesh can be treated as the inner points of the new closed mesh. After the wavelet transferred, the new unclosed mesh can be achieved by removing the "virtual mirror points" of the closed mesh. Meanwhile, the plane on which the boundary curves located of the unclosed mesh was kept unchanged during the process of the loop subdivision wavelet transformation, which brought convenient in looking for the locating surface in multiresolution-based mesh NC machining.
High-altitude balloon integration/opening design system
Ma Yunpeng, Wu Zhe, Lü Mingyun, Liu Dongxu
2010, 36(1): 61-64.
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A high-altitude balloon design system based on a new framework was developed. The design theory of integration,opening source and multi-object contrasting were imported. Meanwhile, the object-oriented method was used to conform the data. The project could be designed by using the opening function of user-defined developing and baseline comparing of multi-agents.The examples prove that the high-altitude balloon design system can synthetically estimate the analyzing results of model establishing,capability and cost evaluating.And the system can combine the pratical applications such as schematic design, digital manufacturing and flight simulation together.
New energy efficient multicast routing algorithm in Ad Hoc network
Zou Likun, Zhang Qishan, Liu Jianwei
2010, 36(1): 65-70.
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The energy efficient multicasting was discussed. Based on the assumption that each node in the network has a fixed level of transmission power during a multicast session, node-join-tree(NJT) algorithm was analyzed. In order to solve the problem that there may be redundant transmitting nodes in multicast tree resulted from NJT algorithm, a new energy efficient algorithm—refine-multicast-tree(RMT) algorithm was proposed. The complexity analysis and distributed implementation of RMT algorithm were also presented. RMT algorithm locally searched existing multicast tree to find whether there are redundant transmitting nodes in tree. When redundant transmitting nodes exist in multicast tree, RMT algorithm deletes such nodes from transmitting node set and reconstruct multicasting tree. The total energy cost of multicast tree was decreased accordingly and thus a more energy efficient multicast tree was generated. Simulation result shows that RMT algorithm performances well compared with NJT algorithm.
Modeling for assembly structure in mechanical product
Wang Bo, Tang Xiaoqing, Geng Rujun
2010, 36(1): 71-76.
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The model of assembly tree was put forward to describe the assembly structure of mechanical products and their assembly relations.The assembly tree model can deal with the functional extension and strengthen the description of the product structure tree which was defined by the designer through assembly drawings.Product structure tree combined with the operations in assembly process,logic relations and other characteristics.The mathematical definition and modeling of assembly tree were proposed on the basis of its formalized description.The idea to take product function as the transforming carrier for the modeling of assembly tree,as well as the construction methodology and steps for assembly tree were also brought forward under the precondition that the mapping relationship between the product function and its structure was definite.The case in assembly process of a plunger injection pump was studied, and proved the assembly tree model feasible.
Influence of changeful wind on landing safety of carrier-based airplane
Xu Dongsong, Liu Xingyu, Wang Lixin
2010, 36(1): 77-81.
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The mathematical simulation model on the approach process of carrier-based airplane was built up in consideration of complicated environment. The influence of carrier air wake and crosswind on the carrier-based airplane landing safety was researched through computation and simulation. The strongest crosswind that carrier-based airplane can endure while approaching on certain initial circumstance was given. The research results indicate that the carrier air wake disturbance must be restrained through pilot operation during the approach process, or else it would cause remarkable position error and decrease the landing precision. For certain initial approach states, the strongest crosswind that the carrier airplane can endure is certain, and any stronger crosswind would lead to failure in approaching and landing process.
Gas dynamic resonance performance of coaxial injector
Yu Nanjia, Cai Guobiao, Zhang Guozhou
2010, 36(1): 82-86.
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In order to study gas dynamic resonance performance of coaxial injector, high precision and high resolution NND scheme was used to solve Reynolds averaged Navier-Stokes equations. Numerical simulation was used to study process of oscillatory flow in different coaxial injector-resonance tube system. Flow field structure and character were obtained. It is obvious that coaxial injector and circle injector have similar resonance heating rules and flow field character. And resonance heating temperature decrease in every resonance cycle when the areas of coaxial injector reduce. The coaxial injector-s distance range between injector and resonance tube where intense resonance will occur is shorter than that of circle injector, and inlet pressure range of coaxial injector is wider than that of circle injector.
Numerical simulation of a swept backward-facing step flow
Jiang Lijun, Gao Ge, Zhang Changxian
2010, 36(1): 87-90.
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3-dimensional separated and reattaching flow over a swept backwark-facing step of height h at Re=28000 with turbulent upstream conditions was studied for sweep angles up to Λ = 60° using open field operation and manipulation (OpenFOAM). This new open source software was validated by comparison with experimental data, special attention is focus on the 0° condition. Velocity profile, vortex structure, and pressure distribution were released. The results show that the reattachment length and vortex structure vary with the swept angles from Λ =0° to 60°. Generally the reattachment length and spanwise vorticity decrease dramatically after Λ =30°. Object-orientation techniques and the open source computational fluid dynamics(CFD) package named OpenFOAM are also introduced.
Simulation of SCI/RT extending sub-priority loading balance protocol
Cui Jian, Liu Xingchun, Li Zheng
2010, 36(1): 91-94.
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To analyze the loading balance problem, the scalable coherent interface for real time(SCI/RT) TRAIN protocol was simulated by using OPNET . The results show that the incensement of the nodes throughput is quite different from each other, along with the ringlet load increasing. In case of the heavy ringlet load, the down stream nodes far from ticketmaster gained almost zero load, while the nodes near ticketmaster gained almost all the ringlet load. The SCI/RT TRAIN protocol gave the ticketmaster migration method to solve it. According to the simulations of a ringlet of 8 nodes, the ticketmaster migration method can distribute load between ringlet nodes but the performance of its function is very dependent on its configuration. When every node has the ticketmaster module, the method gets its best function. In this work, a new comparative method named extending sub-priority was proposed. It was proven that the extending sub-priority method gets better loading balance and higher node throughput than the previous ticketmaster migration method. On the other hand, based on the simulations of 6 nodes, 10 nodes and 12 nodes ringlets, the proposed extending sub-priority method was proven to be functional in ringlets with different scales.
Observer-based variable structure control for networked control systems
Zhao Xianghui, Hao Fei
2010, 36(1): 95-99.
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A variable structure control scheme was proposed for the networked control systems with the networks existing between sensors and controllers. However, the full state of plant can not be directly measurable, so an observer-based controller was established. If the considered delay is smaller than the maximum admissible delay, the observer gain matrix can be calculated by solving a linear matrix inequality that guarantees the error system to be exponential asymptotically stable. The controller gain matrix can be determined by using pole placement or optimal control method and the main results can guarantee the sliding mode to be exponential asymptotically stable. Using the exponential reaching index can adjust the corresponding parameters to weaken the jittering so that the required performance of systems is ensured. A simulation example was given to illustrate the feasibility and effectiveness of the proposed method.
Aircraft carrier hydraulic arresting gear arresting force modeling and simulation
Zhang Minghui, Yuan Li, Hong Guanxin
2010, 36(1): 100-103.
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A certain aircraft carrier hydraulic pressure arresting system was studied. As the main arresting forcing producing components, the mathematical models of the hydraulic block system and pulley buffer system were established according to the basic theory of hydraulic transmission system. Using these two models, combining the dynamic models of the arresting cable and the aircraft-s landing process, a series of numerical simulations were carried out under different aircraft weight and landing velocity. The simulation value was compared with trial value and the difference was studied. The result showed that the pulley buffer system can reduce the tension of the arresting cable effectively and that the change of the control valve can realize the arresting of aircrafts with different weight within around 100m, which also verified the rationality of the model.
High-resolution multi-mode SAR system designing method
Li Wei, Li Chunsheng, Chen Jie, Yu Ze
2010, 36(1): 104-109.
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In view of the current trend of space-borne synthetic aperture radar (SAR) developed toward to the high-resolution, multi-mode direction, considering the characteristics of space-borne SAR system in various modes. The integration indicator system of space-borne SAR system was sumd up. Based on the indicator system, a designing method of high-resolution, multi-mode SAR system was proposed, and the integration system designing flow was given. The analysis was focused on radar antenna design parameters, radar system design parameters, radar transmitter power selection. The method was validated by taking an example for a foreign high-resolution, multi-mode SAR system. Based on overall technical indicators and orbital parameters of the example system, the central electronics equipment parameters, antenna parameters and beam position parameters were designed, and the system performance was analyzed. The designing method overcomes the limitations of current methods and provides technical support in the development of high-resolution, multi-mode space-borne SAR system.
Quantificational evaluation method for key technologies of hypersonic vehicle
Xu Dajun, Cai Guobiao
2010, 36(1): 110-113.
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To improve reasonableness in development strategic research and project argumentation, a quantificational evaluation method was brought forward. Based on divisiory development stages and technology sorts, key technologies of hypersonic vehicle were collected and classified. The quantificational evaluation method was applied with aims of proposed evaluation criteria to evaluate technology key level. Sort order by key technology quantification shows result accord with general consideration, at the same time result also proves quantificational evaluation method has potential effect and worthiness.
Auto test system resource description method based on XML
Yuan Qingfeng, Lu Hui, Shen Shituan
2010, 36(1): 114-117.
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Aiming at the problems of information sharing and interoperability in ATS(automatic test system), XML(extensible markup language) was used for ATS modeling, including test equipment, ICA(interface connector assembly), test adapter and UUT(unit under test). Test equipment capabilities and UUT test requirements were described by unified STD(signal and test definition) standard, and automatically allocating available system resources to a given set of test requirements was achieved. Dynamic mapping relationships between test equipment capabilities and device physical ports were described by importing the concept of logical resource which is a logical entity that usually represents some internal capability of the instrument. The experimental result shows that adapting XML as ATS modeling language improves the development efficiency of ATS modeling and information interoperability degree.
Economic affordability of aircraft conceptual/preliminary scheme based on uncertainty
Lü Mingyun, Sun Kangwen, Ma Yunpeng, Wu Zhe
2010, 36(1): 118-122.
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The uncertainty in research cycle was considered to be an important influence on aircraft conceptual/preliminary scheme evaluation (ACSE).Through the classification of uncertainties during the aircraft design process and analysis of their corresponding treatment methods, the probability multiple-criteria decision-making (MCDM) method was made up, which was based on interval number analytic hierarchy process (AHP) and the robust design (RD). It could be used to deal with the evaluation of aircraft conceptual/preliminary scheme, when the process exists a vast amount of uncertainty. Meanwhile, the result of the assessment was more scientific than traditional method. Taking account of new technology and life cycle cost fluctuation impact on design options, the above methods were utilized to analyze the economic affordability of aircraft conceptual/preliminary scheme (EAACS). And then, the structural model of EAACS was established. The result of analysis verifies the validity of the above methods.
Target threat assessment of air combat based on support vector machines for regression
Guo Hui, Xu Haojun, Liu Ling
2010, 36(1): 123-126.
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Target threat assessment method for air combat was a key problem of cooperative multiple target attack. Aiming at the deficiencies of traditional target threat assessment method for air combat in calculating the weights, a new assessment method based on support vector machines for regression was proposed. An improved distance threat model was proposed based on analyzing the existing target threat assessment methods for air combat which had disadvantages in distance threat model. The model of target threat assessment for air combat was established based on support vector machines for regression, then using this model the threat of some supposed air combat target was evaluated . The simulation results show that the method has good ability of forecast, which can accomplish target threat assessment for air combat fleetly and exactly.

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