Abstract:The propagation mechanism of detonation wave procreant in mixed gas is analyzed. The basic relation between the parameters of the detonation wave in propagation process is established. At the different pressure ratios, the detonation wave characteristic parameters are calculated, the backwards and forwards mach numbers of the detonation wave are obtained. The calculation method of thermal efficiency and entropy production with detonating combustion is deduced. At the different pressure ratios, the variety rule of thermal efficiency and entropy production are calculated. Finally, the detonation cycle is compared with Brayton cycle and Humphrey cycle, the results show that the detonation cycle is higher than the Brayton cycle and the Humphrey cycle in cycle thermal efficiency.

Abstract:To treat with accumulative damage brought by environmental stress, a prognostic framework and a prediction method for electronic equipments are proposed, which cover the whole life cycle of the electronic equipments. The conception of prognostic capability is put forward for the first time. The design for prognostic ability is carried out by adopting auxiliary software eXpress at the design phrase of equipment. With the working data of equipment in practical environment, three improved neural networks are studied to predict the developing trend of characteristic parameters. By fusing single prediction methods with multi-rules, one combined fault prediction method based on information entropy theory is proposed to enhance the reliability of prediction results. The application of prognostic framework to one type of electronic equipment has verified the feasibility of the framework. And the prediction results show that the combined prediction method is stronger than single prediction methods in robust ability and stability.

Abstract:Advanced Upper Stage (AUS) is an important aircraft for future spaceflight. Based on AUS's thrust characteristic and assignment demand, the problem of AUS's quick orbit maneuver optimization is transformed to that of Minimum-time orbit maneuver using finite thrust. Firstly, a multi-restriction and minimum-time optimal model on impulse thrust is established, and the Improved Differential Evolution (IDE) algorithm is used to achieve global optimal solution. Secondly, a correct model on finite-thrust is built to modify the optimal solution by impulse thrust. Finally the solution of Minimum-time optimal orbit maneuver is obtained by finite-thrust. The simulation of quick orbital rendezvous has verified the reasonableness and correctness of the model and algorithm, the obtained terminal position error is 1.0 km magnitude and can be further corrected by terminal orbit adjustment.

Abstract:Sometimes planes may dash out of runway when taking off and landing. In order to ensure the safety of the planes, we should take care of safety precautions in planning and design of airdrome. In this paper, a mathematical model of the plane-wheel and arresting system of sand is built. Through this model，in combination with terramechanics theory and the practical factor that the drag load of wheels should conform to the design range of undercarriages，the paper has discussed the buffering zone in detail in designing formula and approach. Also the geometric design requirement and design steps of the buffering zone are summarized, and the feasibility of the designing method is verified by living examples, which provide a theoretic foundation on the mechanics performance and independent development for the further research on soft-ground arresting system.

Abstract:With regard to the problem of target threat assessment for air combat. In the improved TOPSIS the subjective and objective factors are synthetically taken into account, so the combination weight is gained by combining the subjective weight of threat assessment index gained by IAHP with the objective weight of threat assessment index gained by the maximal deviation. The mathematical model of evaluating target threat for air combat by improved TOPSIS is established. Firstly, a Canonical decision-making matrix is established; secondly inter-zone positive and negative ideal solutions are fixed; thirdly the distances are calculated between every target and positive (negative) ideal solutions. Finally, the correlation between each target and the ideal solution is calculated. An application example is given and the results show that target threat assessment indexes are the same under three different combinations of weight factors and the method is reasonable and effective.

Abstract:For the purpose of evaluating the effectiveness of space weapon system, this paper firstly analyzes the structure of space weapon system, then the guide line of effectiveness evaluation of space weapon system is built. Aimed at the characteristic that the information of space weapon system is partly known and partly unknown, an improved demarcating matrix method of determining the weigh is put forward, a new evaluation model which combines grey theory with analytic hierarchy process for effectiveness evaluation is presented. Finally, an example of the assessment model is calculated and the result shows that the model is reasonable, feasible and effective.

Abstract:Small satellites of distributed Space-Based Radar(SBR) are inevitably affected by the perturbation. The perturbation affects not only the satellite formation but also the sparse array beamforming of radar. From the satellite relative motion equations, by using orbital perturbation equations and introducing the formation configuration parameters in, simulations on distributed SBR satellite formation using space circle formation are performed according to the requirement that the spacing between the distributed SBR.and each member satellite should be small and stable. By using the simulation results of distributed SBR satellite formation under the influence of J2 perturbation, the beamforming simulations of distributed SBR and analysis of the beam pointing offset are given, which provide an important reference to the research on the beamforming technology of distributed SBR.

Abstract:In order to improve the ranging accuracy of dual-channel gain modulation array three-dimensional imaging radar system, taking into account the compactness of the system structure and based on the working principle of TDI CCD which can make use of drive circuit to cumulative exposure information of multi-level of the same point, CCD replaced by TDI CCD as photo detector is presented. According to the ranging principle of this three-dimensional radar, ranging formula and ranging accuracy formula of imaging system are derived. The impact of the level of TDI CCD and the absolute error of velocity mismatch on range accuracy and the modulation transfer function (MTF) is studied. And the analyzing result shows that the accuracy of the distance can be improved to times of the original by this method, and the high precision motion compensation can be realized without additional motion compensation device.

Abstract:In space laser communication system, acquisition, tracking and pointing (ATP) technology is quite important. The pointing precision of the ATP system is a decisive factor in the success of the whole communication system. The artical mostly analyzes the compound axis tracking in space laser communication system. Firstly, the conception of the optical inter-satellite communications and the excellences of realizing the inter-satellite communications by laser are introduced. Then the traits of compound axis tracking are analyzed, the field of view matching of compound axis tracking and its capability analysis are given. Finally, through the simulation and comparison the conclusion that choosing appropriate bandwidth and bandwidth ratio can restrain system error is obtained.

Abstract:The systematical error of the multi-beam continuum scanning of laser satellite communication mainly arises from the time information feedback and detection part. By analyzing the formula for computing the distance between the target location and the scanning centre, the variation trend of the detection probabilities on different scanning locations with the trend of MSE and the step length is drawn. A conclusion is found that arranging the area of the largest probability of the target satellite appearing on the later position of the scanning tracks can reduce errors happening. The digital simulation of identification probability in a scanning cycle shows that when the system time detection precision reaches 4×10-3s, the error probability will be less than 1%.

Abstract:Atmospheric makes the receiver produce laser power attenuation, light intension scintillant beam excursion phenomenon. The operating performances of the laser communication, laser range finder systems and etc. are seriously limited. Now the commonly used theory and research methods in atmosphere transmission characteristics are all based on the research results of foreign countries. Therefore, the research on atmosphere characteristics in the laser transmission channel is very important and necessary. The theory model of the attenuation effect caused by atmosphere absorption, atmosphere scattering, and the effect model of atmospheric turbulence caused by strong light, drifting and expanding of beam and so on are established. Based on the analysis of the above each model, the simulations are focused on the theory model of atmospheric absorption and scattering, and on the effect model of the atmospheric turbulence on the laser transmission characteristics. The simulation results show that atmospheric absorption and scattering will cause power attenuation. Atmospheric jitter of laser speckles effect, beam bending and expanding will influence the tracking accuracy and precision ship-swaying alignment. The fluctuation of power by atmospheric turbulence will affect communication rate and bit error rate. Finally the research on the laser transmission characteristics in the atmosphere is prospected.

Abstract:Several methods utilized in designing microwave photonic phase shifter in the phased array antenna are compared and analyzed, the theory of the fiber vector sum microwave photonic phase shifter is investigated, and the structure of the phase shifter is designed. Variable directional coupler and polarization-maintaining fiber are used in the structure, which can reduce the complexity of the phase shifter and the coherent interference loss, thus enhancing the controllable performance of the phase shifter. The accuracy control of the fiber is analyzed and the scheme contains four polarization-maintaining fiber is given to achieve the phase shift of . The experiment with this phase shifter scheme is made, and the result shows that the scheme is practical and feasible.

Abstract:Aimed at the problems and requirements of the simulation of satellite communication network, this paper firstly analyzes the basic requirement of the simulation system from the characteristics of satellite communication network and presents the feasible method and approach at the present time. Then, the paper again analyzes the current simulation technology and tools from the simulation method, modeling environment, applicability and simulation granularity , which enriches and expends the idea of distributed simulation technology of satellite communication network; finally, proposes a distributed simulation system design for satellite communication network based on the idea of distributed simulation. The simulation system is composed of two-level and three-category system framework, by which the multi-level and multi-granularity simulation can be implemented; and its minimal simulation granularity reaches bit grade, which provides a foundation for both design and optimization of satellite communication network, and is of great value in theory and application.

Abstract:Studying effective routing strategies has become a critical issue in construction of LEO satellite networks because satellite network resources are very limited and maintenance costs are very great. Firstly, features of LEO satellite networks distinct from terrestrial networks are summed up according to their effects on routing issues. Subsequently, a survey of various routing strategies paying particular attention to these problems from aspects of topology, routing refreshment and load balancing is provided. By analyzing the characteristic of routing schemes in their various aspects, a foundation of designing more effective routing strategies to meet the needs of future applications is laid.

Abstract:Single event effect in near space is investigated via numerical model simulations and circuit simulation of inverter with feature size 0.1μm. The numerical simulation results show that the critical charge of microelectronics device is decreased with supply voltage and the sensitive cross section is increased with the decrease of the critical charge, which leads to an increased single event upset rate in the device in near space, however single event upset rate is also decreased with the rising of the near space height. Moreover, the single event upset is observed in the inverter with SPICE circuit simulation by the pulse injection. The obtained results are helpful to performing a deeper study of the single event effect in near space and also provide a theory guide for radiation hardened.

Abstract:Normally, the original components are lessened or enlarged proportionally to build the geometric similar models when large scale components are tested or studied by means of finite element analysis (FEA). In order to ensure that the same stress-strain states present between the considered model and the original component, the loads corresponding to the original components in proportion should be applied to the geometric similar models. Therefore, it is important to study the load relationships among these geometric similar components with the same stress-strain states. Based on the stress expressions of middle point on the below edge of immobile rectangular cross section beam, the loads'+H26 theoretical relationships are obtained using the similarity theory. The correctness of these relationships is verified by the components under elastic and/or plastic stress-strain states. The conclusions are shown as follows: for the two components with geometric similar coefficient kl, if the concentrated force coefficient is kl, the uniformly distributed line force coefficient is kl, or the uniformly distributed plane force coefficient is 1, then the two components are completely the same in stress-strain state.

Abstract:The general method of improving the transmission characteristic stability of a frequency selective surface is to miniaturize its unit cell. By loading capacitor and increasing the electric length, this paper designs a dual stop-band miniaturized frequency selective surface. With two periodic structures the proposed frequency selective surface demonstrates the dual stop-band quality, the lumped capacitor between the cross structures can greatly reduce the series resonance frequency and realizes lower stop-band characteristics in S and C band, the meandering lines will increase the series inductance to achieve higher stop-band in the Ku band. The simulation results demonstrate that this structure keeps the excellent transmission stability with respect to different incidence angles. Meanwhile, because the designed frequency selective surface is nice in symmetry, its transmission characteristic is identical for the TE and TM modes of plane wave. This paper verifies the feasibility of the miniaturized method by loading lumped capacitor and increasing the electric length, which is of great reference value for designing frequency selective surface.

Abstract:As for the multi-sensor target decision-making system, with the affection of the opponent and the environment, the use of D-S combination rules in dealing with high conflict information will always arrive at a counter- intuitive conclusion. In this paper, an improved evidence combination rule is proposed. Firstly, conditional Boolean algebra distance is applied to define drop-falling distance, from which drop-falling similarity is deduced. Then, the credibility of evidence, as the weight of significance in evidence combination, is defined from the drop-falling similarity. Finally, the evidences are combined according to Murphy's combination rule. Both theoretic analysis and numerical examples confirm the validity of the proposed approach and the superiority to the existing methods in combining conflicting evidences.