Abstract:In order to apply intelligent technology to enhance the intelligent capability of spacecrafts, the intelligent level from deployment viewpoint was given. The start point of qualitative levels is automatic, autonomous and autonomic. It includes such capabilities as execution, self-learning, system self-management, mission self-management, thinking and planning from the bottom up. The behavior degrees are bottom-reactive, middle-program and high-thinking. According to the above capability levels, a 5-stage model and an intelligent architecture named “people shape architecture” were proposed. A human-body shape architecture was formulated with two supporting technologies (plug and play, autonomic control) to construct intelligent body on higher level. In this model, based on spacecraft onboard interface services and ESA packet utilization standard services, management information base and electronic data sheet were used for dataoriented design. Corresponding to the intelligent level, appropriate supporting capability of ground system was discussed. People shape architecture has some features including layering, modeling, unification for constructing of intelligent bottom-up architecture, and is open to use intelligent technology in higher layers.

Abstract:Increasing attention has been paid to near space plane in recent years. In the present study, a multi-module RDCRC (rocket dual combustion ramjet combinedcycle) engine was proposed to power the near space plane and its performance was analyzed. The plane was designed to drop at about Mach 0.8 and 10 km above sea level. Under the gravity and the combination thrust of the engine, the plane accelerates to about Mach 2 at 5~8 km above sea level. Then, it climbs up and accelerates the near space under the ejector-ramjet mode or DCR ramjet mode. The ejector-ramjet mode provides higher acceleration with less efficiency, while the DCR ramjet mode provides more efficiency and lower acceleration, thus the mode can be transformed according to the actual situation. Finally, the plane climbs up to about 26 km above sea level, accelerates to Mach 6, and starts to cruise in DCR scramjet mode. A trajectory optimization was carried out for air launch and surface launch, and the obtained results show that the air launch can save about 37% propellant with Mach 6 and 26 km above sea level, and there lies a negative optimal initial flight angle that leads to an optimum ratio between the residual mass and the initial mass.

Abstract:In order to further improve the penetration ability of hypersonic vehicle, the low-observable glide trajectory optimization method for hypersonic vehicle was proposed. The radar cross section of 180°×360° direction of the aircraft was considered. The Gaussian filtering method was used to smoothing the original data, which was characterized by many spikes. This can improve the convergence of optimization problems without changing the trend of the original data. In order to enable the RCS (radar cross section) data to have strong fidelity, the cubic spline interpolation method was used to call the discrete data. The modelling of the low detectable glide trajectory optimization problem of hypersonic vehicle was completed. Setting the radar detection probability as the objective function, the hp adaptive Radau pseudo-spectral method was used to solve the problem. The stepwise calculate strategy was adopted to further improve the optimization efficiency and convergence performance. Simulation results show that when compared with the trajectory who takes the shortest flight time as the goal, the given method can effectively reduce the radar detection probability.

Abstract:In order to achieve fast assignment of gravity anomaly for skip-gliding trajectory in hypersonic speed, an adaptive grid assignment model was proposed, and the generalized extension approximation algorithm was optimized based on the inverse distance weighting theory, the approximation error of the model was analyzed as well. The space of the assignment model was divided at two levels. The first level grid was divided according to the standard ballistic airspace, and the second level adaptive grid was built online according to the actual trajectory of the missile. According to the data of the first level grid nodes, the data of the second level grid nodes were calculated by optimized generalized extension approximation algorithm. Finally, the gravity anomaly value of the actual ballistic points was calculated by interpolation algorithm within the second level grid. The simulation results show that the approximation accuracy of the optimized generalized extension adaptive grid model is higher than that of the general assignment method under the grid with same size. Under the same precision, the maximum grid length of the assignment model is larger than the general assignment method, which can the number of grid division and the amount of data stored on the missile.For the different gliding direction and gliding distance of the jump gliding trajectory, the drop point deviation corresponding to the gravity anomaly approximation error less than 5 m. On the premise of satisfying the calculation speed, this assignment model improves the accuracy of the traditional assignment method and reduces the amount of storage on the missile, and has a certain value of engineering application.

Abstract:A four-strut supersonic ejector with two-dimensional nozzle configuration was tested in cold flow, the performance of start and load match properties were analyzed. The experiment results indicate that the static pressure of suction chamber in four-strut supersonic ejector is less than 3 kPa and the pressure of ejector inlet chamber in delay status is 15.9% lower than that in start status. In the aspect of load match property, the four-strut ejector with small entrainment ratio and big pressure ratio has a quite obvious advantage. When the entrainment ratio is 0.04, the corresponding pressure ratio is 11.21; when the entrainment ratio is 0.10, the corresponding pressure ratio is 11.21. Therefore, the multi-strut supersonic ejector with two-dimensional nozzle configuration has good performance of start and load match properties, thus possessing considerable potential value in engineering.

Abstract:In consideration of the limitation of TRSM (typical response surface method), a MRSM (modified response surface method) which was based on the inner connection between optimization parameters and appointed response was put forward. Several numerical experiments were conducted, and the results were compared with the predicted values of both models. The comparative results show that the MRSM′s predicted values are more uniform than TRSM′s and the max error absolute value is smaller than TRSM′s. By using genetic algorithm, the MRSM is optimized whose aim is to minimize the weight of flange and an ideal result is obtained.

Abstract:In order to improve the integer ambiguity resolution successrate and the baseline precision, a strategy of stochastic modeling for precise relative positioning aimed at hybrid constellation BDS was proposed, namely the hybrid stochastic modeling strategy. In the new strategy, variances of singledifference observations were estimated with the leastsquares variance component estimation. After that, the observation variances of different orbits satellites were fitted with different models, carriertonoise ratios dependent model was used to fit the observation variances of geostationary earth orbit satellites, and two individual elevationdependent models were used to fit observation variances of inclined geosynchronous satellite orbit and medium earth orbit satellites. Then the stochastic model of observation model was constructed in real time with these different fitted models. The experimental results reveal that, when compared with the traditional, simplified model and the sole elevation or carriertonoise ratios model, the proposed hybrid stochastic model is more realistic in reflecting the noise property of observations of different orbits satellites. And it has an overall better performance in integer ambiguity resolution success rates and relative positioning precision. Hence, the hybrid stochastic model is more suitable for BDS in high precision positioning applications.

Abstract:For the hybrid multi-attribute decision making problems with completely unknown attribute weights, a decision-making method based on the prospect theory and the evidential reasoning was proposed. The decisionmaking information of three kinds of hybrid attributes including precision numbers, interval numbers and linguistic variables was unified by intuitionistic fuzzy numbers and transformed according to the prospect theory. An attribute reliability evaluation method based on intuitionistic fuzzy entropy and similarity was proposed. And the attribute weights were determined by combining the importance of attribute. The evidential reasoning algorithm was used to assemble the attribute information to obtain the comprehensive prospect values of alternatives, and then the alternatives can be sorted. The results of numerical example analysis show that the proposed method has a strong discriminating ability and can effectively reduce the uncertainty of decisionmaking results. The proposed method has good applicability to hybrid multi-attribute decision making problems.

Abstract:In order to accurately and quickly predict the storage life of rubber, the acceleration coefficients at different acceleration temperatures are calculated based on the stepping stress accelerated aging test of high temperature, and the acceleration factor and absolute temperature reciprocal curve was obtained. For the nonArrhenius characteristic, a power exponential factor was introduced, and a modified Arrhenius model was employed to fit the acceleration coefficient. From the slope of the logarithmic reaction rate and the absolute temperature reciprocal curve, the equivalent linear activation energy of the modified Arrhenius model at different temperature was calculated, which indicated that the activation energy decreased at low temperature. The aging life model at low temperature was established and the aging life of the rubber at 10 ℃, 20℃ and 30 ℃ was evaluated respectively. Evaluation result shows that, it can provide reference for nonArrhenius analysis and life prediction in the corrosion process of related polymer materials.

Abstract:In order to accurately evaluate the effectiveness and failure pressure of cracked pipelines repaired by fiber composites under static load, a numerical model for the failure of cracked pipelines repaired by composites was established.The numerical model simulated the crack propagation of the pipeline by expanding finite element method. The cohesive element was used to simulate the debonding failure of the adhesive layer. The failure of the composite material was determined by the maximum stress failure criterion. The proposed numerical model of failure was verified by hydrostatic burst test. The experimental results were in good agreement with the numerical results. According to the results of numerical analysis, when the internal pressure increases to a certain value, the initial crack of the unrepaired pipe gradually expands along the axial and wall thickness directions, and then the inner wall unit of the pipe expands into a real crack. At the same time, the real crack runs through the entire wall thickness.The burst failure pressure decreases exponentially with the half length of the initial crack.The different repair conditions of cracked pipelines repaired by composite exhibit the same failure mode:under the monotonically increasing internal pressure of the pipeline, the internal surface of the pipeline first appears a cohesive crack, and the cracking tendency of its outer surface rises sharply, making the stress of the composite material layer rise sharply and reach the ultimate strength.And there are corresponding critical values of the composite layers for different initial crack sizes.

Abstract:To discover correlations in massive telemetry data efficiently, a novel correlation knowledge discovery method based on the improved MIC (maximal information coefficient) was proposed. The Mini Batch K-Means clustering algorithm was used to discretize data in the precursor process; the mutual information between two variables under this partition was calculated and normalized by information entropy instead of maximal entropy to obtain the information coefficient; the MIC was selected as the measure of variable correlation. Aflerwards, the method was applied to the correlation analysis of the quantum satellite telemetry data, and the results show that the proposed method can effectively solve the problem of MIC measure bias to multivalued variables compared with the method based on dynamic programming algorithm, the time complexity dropped from O(n^2.4)to O(n^1.6), and it is an effective method for large-scale telemetry data correlation analysis.

Abstract:To estimate the compensation value reasonably with simulation model under the situation of limited data of proof shooting, the virtual proof shooting method for naval gun considering the reliability of simulation was studied. The adapted weighted Bayesian estimation considering the reliability of simulation was studied. On the one hand, the method for calculating reliability of simulation was analyzed; on the other hand, the adapted weighted Bayesian estimation algorithm considering reliability of simulation was studied. On the basis, considering the principle and requirement of virtual proof shooting, the model for estimating error of firing parameters based on the adapted weighted Bayesian estimation considering reliability of simulation was built. The results from simulation shows that: the adapted weighted Bayesian estimation considering reliability of simulation can verify the reliability of the simulation model efficiently with the test data, thus estimating the target distribution efficiently; the proof shooting method can use the advantages of simulation model and shooting specimen, and realize the reasonably estimation for error of firing parameters, and then, achieve the goal of effectively improving the accuracy of proof shooting.

Abstract:As the important indices for reflecting the comprehensive performance of the battery, the parameters of lithium-ion are unavailable by direct observation. Through identifying internal circuit parameters by establishing multiple linear regression model, a new method for the state of charge estimation of lithium-ion batteries by indirectly observing the batteries balance electromotive force was proposed. The equivalent capacitance was introduced to represent capacity character of lithium-ion batteries in this new method, which was based on an improved Thevenin battery model. Through measuring changes of open-circuit voltage and charge before and after the discharge process in a cycle period, the equivalent capacitance can be recognized in a long time scale. As the main variable for estimating state of charge, the balance electromotive force can be dynamically estimated through the equivalent capacitance in a short time scale. Finally, a pulse discharging experiment of a cycle period verified the effectiveness and accuracy of the improved battery model and the proposed dynamic identification method.

Abstract:On the premise of unknown “total” disturbance model, aiming at tracking accuracy of time-varying signals for linear extended state observer, a feedforward observation compensator was designed. After analyzing the observation principle of linear extended state observer, by linearizing the disturbance and neglecting the dynamic response of the error system, the quantitative expression of the static observation error was derived in the time domain. Then by using the estimated value of the disturbance instead of the true value, the feedforward compensation for the observation was made. The feasibility of substitution was analyzed. The results proved that this compensator can reduce the amplitude of the observation error and has a certain pre-correction effect on the phase lag of the state observation. This compensation idea was then extended to the nonlinear extended state observer. The simulation validates the effectiveness of the compensator to improve the observation precision and speed up the convergence of the error. The experimental results further indicate that the introduction of the compensator can significantly improve the control precision of the whole active disturbance rejection control system. Thus the feasibility of this kind of compensation idea gets proved.

Abstract:In order to calculate control volume, the traditional flocking control algorithm is necessary to obtain the position and velocity information of adjacent particles within the communication range, a novel flocking algorithm without the velocity information of the adjacent agent for UAV (unmanned aerial vehicle) was proposed. Firstly, all UAVs within the communication range were regarded as obstacles and the control quantity was obtained by the unified calculation method. Some related theories were proved based on Lyapunov stability. Afterwards, the improved flocking algorithm was applied to UAV swarm control by establishing a six-degree-of-freedom UAV linearization control model and the whole UAV swarm consisting of the tracking loop and guidance loop is stable through selecting appropriate control parameters. Finally, the effectiveness of the proposed algorithm is verified by the numerical simulations.

Abstract:Aiming at the lack of robustness for current position estimation method to rotation parts in aerial non-cooperative targets, a position estimation method using cross range cell entropy and local range cell entropy was put forward, which was based on analyzing of distributing characteristic of rotation part in high resolution range profile and inverse synthetic aperture radar. The proposed method promoted the accuracy of signal separation for rotation part when inverse synthetic aperture radar imaging was applied to aerial non-cooperative targets. The real data simulation results showed validation of the estimation method, and the steadiness of the estimation method was further tested by applying real data with additional noise.

Abstract:An important concept in equipment parallel simulation is the model evolution driven by realtime data, but there is still a lack of model evolution method for specific application areas. Against the background of remaining useful life prediction for hybrid degradation equipment with unknown discrete shock, the polymorphic Wiener state space model was regarded as the evolutionary object and a model dynamic evolution method of equipment parallel simulation was put forward, including the interactive multiple model strong tracking filtering based model soft switch and the expectation maximum algorithm based online estimation of model parameters. Furthermore, the parallel simulation based realtime prediction of equipment remaining useful life was realized. A case study was conducted by using a bearing degradation data. The results show that the method can effectively improve the simulation fidelity and the remaining useful life obtained by the proposed method has higher prediction accuracy and smaller uncertainty, implying a high practical engineering value.

Abstract:Considering the inability of current visualization technology of high dimension multiobjective to effectively display preference information of decision-making, a new graphical visualization method of interactive ndimension Pareto front method based on radial axes plots was proposed. Firstly, the fitness functions were standardized to eliminate dimensional gaps. Secondly, the least square problem model was established according to the interactively updated axes matrix and solved by the Moore-Penrose pseudoinverse method. Sequentially the diagram of dynamic Pareto front distribution was obtained, which effectively shows the data information of each dimension objective, the variation tendency towards performance and the preference information for decisionmakers. Finally, the visualization model is devised and the extensive experimental analysis is provided to investigate the Pareto optimal solutions for decision-makers.

Abstract:A layout optimization model about functional tanks in semi-submersible repair vessels was established under the premise that relevant technologies can be reached. The objective function of this model was put forward under the consideration of three factors about maintenance and repair tanks, such as tank size, tank adjacency, and tank global position. The constraints of this model were set to meet initial metacentric height requirement and guarantee to float on even keel. This optimization model was solved by a two-stage algorithm of combining greedy dropping heuristic algorithm with programming solve. The functional tanks layout solution was obtained with the aid of a semi-submersible hull whose capacity reaches the level of 50 000 tons. This testified the rationality of this model and practicability of this algorithm. And the number of feasible layout solutions shows an upward trend with the increase of the maintenance equipment weight coefficient. This method can improve scientificity in decisionmaking process about functional tanks′ layout in semisubmersible repair vessels.

Abstract:Aiming at the requirement of generating the linearly chirped microwave signal with high frequency and large bandwidth, an approach based on cascaded MZM (Mach-Zehnder modulator) to generate linearly chirped microwave signal with highfrequency and large-bandwidth via frequency and bandwidth multiplication was proposed. From the theoretical analysis, the linearly chirped microwave signal with variable multiplication factor of the carrier frequency and bandwidth was generated by properly adjusting the direct current bias points and the modulation index of the cascaded MZM. On the basis of this, the corresponding simulations were performed on the optical system software platform. The linearly chirped microwave signals with the carrier frequency and bandwidth of 40 GHz, 15.07 GHz and 58.25 GHz or 19.5 GHz were generated from a 5 GHz or 2 GHz linearly chirped drive signal respectively. The simulation results verify the feasibility of the proposed approach and the superior compression of the generated signal.

Abstract:When the desired signal and the interference are in the same direction, in order to improve the communication quality in the ELF (extremely-low-frequency) communication effectively, a kind of interference suppression algorithm based on analog circuits preprocessing and improved GSC (generalized sidelobe cancellation) algorithm was proposed. The magnetic antennas and preamplifier circuits with lower noise were designed, and the magnetic sensor with high sensitivity was produced, which can suppress 50Hz interference and its harmonic components effectively. In view of the weak desired signal in ELF communication, on the basis of the GSC algorithm, several improvements have been made to provide more reference information about interference for the main channel, which can improve the original GSC algorithm′s performance furtherly and address the problem of the traditional algorithm effectively. In order to validate the effectiveness of the proposed algorithm, an experimental platform was set up under the laboratory environment and multiple sets of controlled experiments were performed. Experimental results show that the improved GSC algorithm is better for the improvement of SNR and the noise floor, compared with the original GSC algorithm, regardless of whether the desired signal and the interference are in the same direction.

Abstract:In order to realize the intelligent identification of signals modulation effectively, a novel modulation recognition method of MPSK(multiple phase shift keying）signals based on deep learning was proposed. The cycle spectrum of the MPSK signals were analyzed firstly, and the two-dimensional features information were obtained by extracting the contour map of the MPSK signals cyclic spectrum. Then, the two-dimensional features were trained by using the convolution neural network of deep learning. Finally, the effectiveness of the proposed modulation recognition method was verified by the test samples. The simulation results show that the proposed method has good recognition performance.

Abstract:A new type of whip antenna with multilayer radiation lobes structure was introduced. By setting up different numbers in parameters like radiation lobe layer number, radius, length, branch number, elevation angle and distribution of radiation lobe on the body of the 10 meters whip antenna, the research of their influences on antenna radiation performance were launched to choose the most suitable structure for whip antenna. The double loading and the broadband matching network for the antenna were designed and optimized, whose simulation results show that the gain and efficiency, compared with the existing broadband whip antenna, are greatly improved, the maximum growth of gain and efficiency are 3 dB and 5% covering the low frequency, which are 5 dB and 35% covering the high frequency,the warping of the pattern is also restrained to a certain extent，so a new structural design method is provided here to improve the existing broadband whip antenna.

Abstract:Aimed at the problem of lack of prior information in the shaft-rate electric field envelope tracking, the basic requirement of ship shaft-rate electric field tracking on the sensor array was studied and a multi initial progressive update extended Kalman filter algorithm based on maximum likelihood selection was introduced. The state space model of ship shaft-rate electric field envelope tracking was established, and the horizontal electric dipole was used to model the ship′s shaft-rate electric field envelope; a multiple initial value model based on maximum likelihood selection was established. Next based on the signal characteristics of the envelope of shaftrate electric field, the requirement of sensor array arrangement was studied. Simulation results show that it is feasible to track ship by the envelope of shaftrate electric field. And it is required that the sensor array must be made up of at least three sensors, which are not in a straight line. Under the condition that the sensor array meets the requirements, the proposed algorithm can effectively solve the lack of prior information in the shaft-rate electric field envelope tracking, and it has a high practical value.

Abstract:The history of precision guidance technologies was reviewed, and the challenges and main developing trends of imaging and detecting technologies for precision guidance were illustrated. Combined with the recent developments of the emerging technologies such as terahertz, quantum and metamaterial, the backgrounds, developing venation, basic principles and advantages of three typical advanced imaging and detecting technologies, namely, terahertz radar, quantum radar and metamaterial radar were expounded. These advanced techniques may have the potential to provide feasible approaches for precision guidance technology to overcome the challenges brought by the future new warfare form. The analysis results will provide some positive guidance and is of significance for improving the strike and intercept effectiveness of the precisionguided weapon systems.

Abstract:Although the identification of pipelines′ inner boundary based on heat conduction has been matured, the quantitative identification of inner boundary of turbulent pipe, which is more practical, has scarcely been reported yet. The steady-state identification of the inner boundary shape of a turbulent pipe with fully developed two-dimensional axial symmetry was studied through the connection of COMSOL and MATLAB, as well as the use of finite element method and Levenberg-Marquardt method. The validity of this method was proved by numerical experiments. The results show that, in a turbulent pipeline with a defective inner boundary, the maximum temperature difference of outer wall and the absolute temperature difference caused by defect do not increase synchronously. During the identification of inverse inner boundary problem, due to the negative growth in the absolute temperature difference, the identification results do not necessarily improve with the increase of absolute temperature difference. The identification accuracy slightly deteriorates at the end of the irregular inner boundary.

Abstract:The moisture absorption behavior of quartz fiber reinforced epoxy panel/PMI core sandwich composites under different temperature and humidity conditions was studied. The quartz fiber reinforced epoxy composite panel, PMI foam and corresponding sandwich structure specimens were treated with different conditions for moisture absorption. Properties of these specimens were studied after moisture absorption. Results show that: firstly, the saturated moisture absorptivity and the moisture absorption rates of specimens are enhanced when they are soaked in water; secondly, when specimens are subjected to moisture absorption at 50 ℃, 60 ℃ and 70 ℃, saturated moisture absorptivity of the specimens dropped more at a higher temperature because of the mass loss in moisture absorption. It was also found that, when specimens are treated in a moisture condition below 60 ℃, the saturated moisture absorptivity of the PMI foam cored sandwich composites can be predicted by combining the moisture absorption rates of panel and the PMI foam counterparts.