Abstract:Multidisciplinary Design Optimization (MDO) of flight vehicles is now a focus of international research in the aerospace field. The engineering application research of MDO, however, falls behind the fundamental theoretical research domestically, which sometimes even leads to the suspicion of the practicability of MDO. On the basis of our research on MDO in the past decade, the difficulties of the engineering application and the relevant key technologies of MDO were analyzed. The international research on engineering application of MDO can be approximately summarized into three stages, the characteristics of which were illustrated with three application examples in flight vehicle design implemented by our group. Finally, the future trends of the MDO engineering application were briefly analyzed.

Abstract:The Uncertainty-based Multidisciplinary Design Optimization (UMDO) method was studied for the conceptual design of fractionated modularized cluster spacecraft (fractionated spacecraft), so as to comprehensively assess and optimize life cycle cost, benefit, system robustness and flexibility under uncertainty. Firstly, the UMDO methodology was introduced, as well as the schematic flowchart of UMDO for the fractionated spacecraft conceptual design. Secondly, the system architecture and assessment criteria of the new concept fractionated spacecraft were explained. The disciplinary models, cost models and benefit models were described, and the uncertainties thereof were modeled with probability theory. Thirdly, a notional earth observatory fractionated spacecraft was used as an example to demonstrate the application of UMDO in the fractionated spacecraft conceptual design. The UMDO problem formulation and UMDO procedure organization were presented in detail. The results show that the mean of the net revenue and its robustness under uncertainty can be greatly improved, which verified the effectiveness of UMDO method for fractionated spacecraft conceptual design.

Abstract:An improved MDO procedure for BLISS 2000 (Bi-Level Integrated System Synthesis 2000), which is named HBLISS (Hybrid BLISS) to find a way out of a difficulty in applications because of the weighting factor, is proposed. The basic algorithm structure of BLISS 2000 was kept and the weighting factor was cancelled, in which the minimum residual error of coupled variables was utilized to coordinate system level optimization and sub-system level optimization. The algorithm structure and flowchart were introduced. The results of Reducer optimization problem show that HBLISS has the superiority in the disciplinary autonomy and convergence, and the improvement is valid.

Abstract:A neighborhood strengthened CSSO-RS is proposed to improve the disadvantages of the Concurrent Subspace Optimization based on Response Surface (CSSO-RS). This algorithm gives rise to an optimization between the system level optimization and subspace level optimization, which greatly improves the coordination affection between these two levels. The optimization region of this algorithm is the neighborhood of the optimal solution obtained by the subspace optimization, and all the design variables are involved in this optimization. The classical test function and an aircraft concept sizing problem were tested, and the efficacy of the algorithm was proved.

Abstract:Aimed at solving the problem of optimization convergence and the global optimization, this research proposes a Combined Optimization Methodology, which combines the global and local optimization methods. The former one can obtain global optimum solution but converge slowly, while the latter one can converge fast and obtain a local optimum solution and can be sensitive to initial value. Firstly, the approximation function of the original problem was built. Then the approximate optimum solution was obtained by the global optimization method. The approximate optimum was taken as the initial value, and the real optimum solution is obtained by the local method optimizing the original problem directly. In order to achieve better approximation, the RBF was improved and Shape Parameter Optimization Radius Basis Function was developed by using the surrogate model. Both of the methods were used in the near space aircraft wing optimization. Results show that the modified interpolation method is more accurate than the Kriging model, and the Combined Optimization can obtain the optimum and improve the convergence speed.

Abstract:The characteristics of interpolated-based surrogate model were analyzed. The oscillation characteristics of interpolated-based surrogate model, an important factor that affect the generalization capacity was put forward. Analysis shows that: when the oscillation of surrogate model is violent, its generalization ability is weak. An evaluation method based on energy function was put forward to evaluate the generalization ability of surrogate model. By calculating the surrogate model’s first and second derivatives, Energy Function Method (EFM) can obtain the oscillation characteristics of surrogate model. The higher the Energy Function, the more serious the oscillation of surrogate model. Thus its generalization ability is worse. Test functions were made, and the results show that the Energy Function Method is efficient in evaluating the generalization ability of the surrogate model.

Abstract:Mutative Scale Immune Clonal Selection Algorithm (MSICSA) based on Multi-population is proposed. In the algorithm, the dominant position of global optimal solution was highlighted by the nonlinear scale transformation of objective function. Memory sub-population was extracted to exchange information between populations. Antibody population was divided into elite, normal and inferior sub-population. To enhance local and global search capabilities of MSICSA, adaptive Gaussian and uniform mutation were applied to elite and normal sub-population respectively and the inferior antibody was extinguished and replaced by new ones. By introducing the niche technology to increase the diversity of population distribution, the algorithm can prevent premature. Test functions and a space antenna optimization were tested. The results show that the optimization capability of MSICSA is more advanced than CLONALG and SGA, and the computational complexity is reduced.

Abstract:A new MDO algorithm named as Subspace Decomposition and Discarding Optimization (SDDO) is advanced here. The optimization is based on the approximation model, of which the main idea is based on the subspace decomposition and discarding. Firstly, the approximation model of a MDO problem was carried on its design space. If the precision of approximation model reaches a satisfying precision, this optimization procedure will be terminated. Otherwise, the design space will be decomposed into two or more subspaces. Then, the optimization will be carried on the approximation of these subspaces. If the subspace has no promise to get better optimization result than the optimum reached by other subspaces, the subspace will be discarded. If the subspace approximation precision has reached a satisfying precision, this subspace will not be decomposed into smaller subspace. If the subspace has not reached a satisfying precision and has promise to get better optima, this subspace will be decomposed into smaller subspaces. The calculation time of this process is related to the numbers of design variables and design space. Function optimization examples show that this optimization algorithm has good performance on calculation time and global optima.

Abstract:Multi-camera relay station is usually used to relay pose parameters among neighboring nodes in the videometric using camera network. An optimization method based redundancy calibration is proposed to solve the problem. Firstly, the number of independent pose parameters, the maximum number of measurable pose parameters and the minimum number of restricted condition were analyzed for a normal multi-camera relay station. Then, the optimized calibrating algorithm for a typical four-camera relay station was given，and the optimized method for general relay station calibration was suggested as well. Finally, a numerical simulation of the proposed algorithm for four-camera relay station calibration was conducted. The results show that the algorithm is feasible and effective.

Abstract:A novel bionic camouflage material, which is constituted of transparent poly（vinyl chloride） surface, chlorophyll/poly(vinyl alcohol) film, high-vapor-barrier water bag and paper, was designed and prepared by simulating plant leaves. The transparent poly（vinyl chloride） surface was used to provide waterproof capability of the camouflage material; the chlorophyll was concealed into the high-oxygen-barrier poly(vinyl alcohol) film to improve its photostability; the water was sealed into the bag of high-vapor-barrier poly(vinylidene chloride) to prevent its vaporization loss; and the paper was used to simulate the spongy mesophyll of plant leaf organs. The result of spectral tests showed that the reflectance spectra of camouflage material and plant leaves, whose similarity was 0.9983, exhibited the same characteristics in visible, near infrared and short wave infrared wave bands, and the spectral characteristics of camouflage material did not change after three months’ sunlight treatment. The bionic camouflage material, which displayed a high spectral similarity with plant leaves and a good weather resistance, is an effective method to take on reconnaissance of hyperspectral imaging hopefully.

Abstract:The fly-cutting technique has wide application in optical microstructure manufacture. A unique method is put forward to achieve fast and high quality optical waveguide microstructure mould manufacture with fly-cutting technique after an analysis of the present complicated process technique. Fly-cutting orthogonal test was conducted to get the optimal process parameters for machining the waveguide mould. It is found that the microstructure surface roughness is sensitive to the cut depth first, the next two are the spindle speed and the feed speed. The optimal process parameters involve such figures as cut depth of 25μm, feed speed of 20mm/min and spindle speed of 800r/min through the experiment analysis considering the stability of the fly-cutting system and machining efficiency. The optical waveguide mold with microstructure surface root-mean-square roughness of 17.1nm was obtained through the optimal process parameters.

Abstract:In the case of equipments’ performance degradation which partially results from measuring, the model which is only based on the degradation data itself cannot reflect the true degradation process, and it is unable to forecast and evaluate effectively, especially when the degradation quantity caused by measures cannot be ignored. In order to solve this problem, firstly, the equipment's degradation process model which contains the damaging quantity induced by measuring was established on the basis of Wiener process; then the method of parameters estimation and real-time updating method for equipment's residual life based on Bayesian theory were presented. Finally, a simulation example was presented to testify the significance of this research and the validity of models.

Abstract:According to the principle of the transformation from the summary of traditional-cradle machine tool to the one of free-form machine tool-assuring the orientation between the cutter axis and the work-piece axis during the process, axis-motion formulas in the form of polynomial for free-form machine tool were fitted with the least square method. The procedure was accomplished via exemplifying No.116 gear generator for traditional-cradle machine tool, and deducing the coordinate transformation matrixes under these two kinds of machine tool. Correctness of the procedure is validated by an example, which shows that the coordinate transformation matrixes under these two kinds of machine tool coincide, the distance between the tooth surface virtually manufactured by axis-motion formulas in the software of CATIA and the theoretical points lies in the range from 0mm to 0.009mm, and the distance can be controlled to a smaller one. The influence of axis-motion error on tooth-surface error was investigated, and axis B was found to be the one influencing tooth surface most significantly. This partially provides theoretical basis for improving the manufacturing accuracy of free-form machine tool.

Abstract:Permanent magnet linear motors are fit for the application of quick acceleration and braking within short distance in electromagnetic aircraft launch systems, but eddy current is likely to be induced by its quick moving. In the acceleration stage, the resistance force deduced by the eddy current can reduce the launch ability of system. On the other side, the force deduced by the eddy current can improve the braking ability in brake stage. This study analyzed the eddy current force in a kind of linear motor with open slot, concentrated winding, and moving permanent magnet. In the acceleration area, the eddy current resistance force deduced by the aluminum sleeve of the permanent magnet mover was analyzed. A method to weaken this resistance force by half open slot and hollow sleeve structure was proposed, and the feasibility was proven. In brake area, a solid stator structure was proposed to take the place of a laminated stator structure, which can increase the eddy current braking force and shorten the braking time. A simplified function has also been formulated for the eddy loss. Simulation results indicate that a hybrid braking technique combining eddy current braking and plug braking can improve the braking ability efficiently.

Abstract:Computer simulation is effective for the optimization of complex system. However, it is time-consuming. Therefore, the number of simulations must be strictly confined. To generate a good simulation plan, an optimized Latin hypercube sampling method is put forward. The method can not only reduce the number of simulations, but also ensure the generated plan of good orthogonality and proportional spacing. Cholesky decomposition was borrowed to generate initial solution, and simulated annealing algorithm was used to get optimized array. Also a dynamic weight parameter was defined to balance different optimization objectives. Finally, an example was constructed. The result shows that the optimized Latin hypercube sampling method can generate a sound simulation plan with less simulation.

Abstract:In the combat simulation of human behavior representation (HBR) preciseness, it is all-important to build the conflict resolution model that can really reflect battlefield behaviors. According to shortages of existing research and analysis of conflict behaviors, this research presents an argumentation-based collaborative CGF hierarchy negotiation model, defines some related concepts, based on which the negotiation process in conflictions was studied and the Utility Theory-based arguments strength qualified evaluation algorithms was implemented, which is used for the selection of optimal proposal and confirmation of common belief. As is testified in fact, it can reflect the real battlefield behaviors under conflicts and ensure the consistency of negotiation during the collaboration process.

Abstract:For the average consensus of multi-agent systems with lth-order chain integrator dynamics, it is important to build the LMI-based delay-dependent stability criterion with jointly-connected topologies. Using the idea of state decomposition, the condition was converted into verifying the stability of zero equilibrium of disagreement system. Considering multiple time-varying communication delays, common Lyapunov-Krasovskii functional was employed to analyze the stability of zero equilibrium. In order to relax the conservativeness, Free-weighting Matrices method was employed in the main results. After matrix order-reduced treatment, the tolerant upper bounds on communication delays were obtained through solving feasible linear matrix inequalities (LMIs). Numerical examples and simulations were presented to demonstrate the effectiveness of the proposed method. Different from the existing literature, the proposed stability criterion was characterized by lower conservativeness, simple formation of the solution, and wide range of time-varying delays. It can be applied to instruct the analysis and discussion of the average consensus of multi-agent systems with complicated communication conditions.

Abstract:News videos contain huge amount of daily information, in which there is a great deal of redundancy and repetition content. Thus it is necessary to analyze news stories’ relationships and generate news topic effectively. This research proposes an approach for generating news video event topic based on stories. K-means cluster algorithm was used to group topic-evolving stories integrating textual and visual features. Based on the similarity and dependency between stories, an event topic was constructed automatically for the news video topic organization and threading. Finally, the generated event topic structure was visualized in event-time space. Experimental results show that the topic structure generated by the proposed approach can facilitate the fast navigation and understanding of the news topic.

Abstract:Assessment of the joint strike plan is a pivotal task for planning and decision-making, and it plays a crucial role in selection and employment of operational art. The challenge is how to model the mapping from plans to mission effectively in uncertain situation. Simulation system is inefficient in evaluating plans, while analytic models are unable to reflect the interaction and overall effect of the target system. The probability reasoning models have currently been utilized extensively in the assessment of military operation, and the typical model is Timed Influence Net (TIN). Stochastic Timed Influence Net (STIN) is an extensional version of TIN that has enhanced the description of uncertain delay in TIN. Thus, the method of STIN based joint strike plan assessment was provided. Finally, a numerical experiment was presented to demonstrate the effectiveness of above method.

Abstract:For surveillance trajectory, a potential semantic content discovering method based on motion features was investigated. In the phase of feature estimation, precise and smooth multi-modal distribution of direction was obtained by combining inflection points of trajectory curve with the kernel density estimation. Then sequential and concurrent temporal patterns of trajectory sub-class were modeled by Hidden Markov Model. With motion feature distribution, a hierarchical trajectory aggregation model based on motion similarity was proposed. Experimental results show that the model can be used to discover potential structure of trajectory set which reflect the motion region information of surveillance scene.

Abstract:The average outage probabilities of the amplify-and-forward (AF) relaying and the decode-and-forward (DF) relaying with/without diversity in Rayleigh fading were analyzed respectively, and the analytical expressions were presented. To minimize the average outage probability, with total transmit power constraint, the statistically optimal power allocation problem of the AF relaying and DF relaying were considered, and also the analytical expressions are provided. Then the statistical optimal relay selection was suggested to further minimize the average outage probability. Though the analytical expressions of power allocation for AF and DF with diversity were obtained under the condition of high transmit SNR, the simulation results show that they are also valid in the low transmit SNR region. Compared with fixed power allocation, the statistical optimal power allocation effectively reduces the average outage probability. Meanwhile, the optimal relay selection further reduces the average outage probability.

Abstract:Aimed at the image registration problem in interferometric inverse synthetic aperture radar (InISAR), the causation of the offset between two ISAR images for different interferometric antennas along one baseline was analyzed. Then a quantitative analysis of the offset and its influence on the following interferometric processing was discussed. It was shown that the sub-pixel offset in the down-range direction and the pixel offset in the Doppler (cross-range) direction induced mismatching of two ISAR images. A novel image registration method based on phase correction was proposed to solve the mismatching problem in InISAR imaging. Simulation results demonstrate that the offset between two ISAR images is compensated effectively when the proposed new method is used, achieving an improvement of the quality of three-dimensional (3-D) image consequently.

Abstract:An authorization model of over domains based on RBAC is presented. The study described an RBAC authorization model based on policies for a single domain firstly, and then it built a network model by extending it to an authorization model for crossing the domains. So it resolved the problem of authorization integrating facing to many applications crossing the domains.

Abstract:The traditional method analyzes the anti-jamming biases by using narrow-band model Hypothesis. On the other hand, next-generation GNSS signals using wider bandwidth make the broadband effect more obviously. Therefore, the impact of narrow-band assumptions needs to be re-examined. This research derives the precise model under the case of DBF processing, and the conclusion is that the array response equals to the inner product of spatial steer vector and the Kroneck product of time steer vector and weights of taps. The research also analyzes the array anti-jam performance biases by narrowband assumption under the multiple factors. The results show that the main reason is the distortion of array response. When JSR is 70dBc, the maximum error introduced by narrow-band approximation model is about 5dB. The intenser the jamming, the bigger the error. At the same time, the error introduced by the above precise model is about 0.5dB.

Abstract:Distinguishing the decoy and the target is the fundamental problem in countering the Towed Radar Active Decoy (TRAD) jamming. In the course of TRAD jamming, the triangular geometry relationship among the missile, the target and the decoy changes. That brings about the differences of Doppler frequency between decoy and target. Thus it provides the possibility to distinguish the target and decoy in frequency domain. Based on the analysis of the frequency separability in the head-on attack and chase attack scenarios, the L class of Wigner Ville Distribution (LWVD), with the advantages of improving the azimuth resolution and inhibiting the cross terms, was adopted to separate the target and decoy. Then by combining the auxiliary information of echo characteristics and attack scenarios, the identity recognition between the target and the decoy was achieved. The simulation results validated the availability.

Abstract:The Target Echo Signal Simulator (TESS) for interferometric SAR was designed and implemented. The TESS can make a hardware-in-loop simulation loop with radar working in interferometric bistatic mode. It recorded the transmitting signal of the master satellite in real-time, supplemented the scene modulation information off-line, and played back the radar echo of master and slave satellite according to the radar PRF. The high digital IF transmitting and receiving technique was used to achieve better harmonic, clutter and carrier suppression performance. The on-line loop correction technique was adopted to correct the amplitude and phase mismatch of TESS in real-time. The measured results show that the indexes of TESS satisfy the design requirements, and the TESS meets the needs of practical engineering of the hardware-in-loop simulation for interferometric SAR.

Abstract:Quantization will be necessary in the digital signal processing because of the hardware’s resource. It is important to improve the performance of the quantizer. An expression of quantization distortion to clip level was derived theoretical for N(μ,σ²)Gaussian pdf signal. Also the expression of the minimal quantization distortion and optimum clip level was deducted. The result of computer simulation is that the expression can be used to estimate the optimum clip level effectively and exactly in the related applications.

Abstract:The formalistic description about classification of information is an important and difficult point in information integration currently. The factor expression theory based on knowledge can describe the relationship between concepts, and also can describe the concept’s semantics through this relationship. This method has uniform frame of knowledge description and strict mathematical theory foundation. This research puts forward the architecture model of equipment total system and life cycle information, and the knowledge expression theory based on factor describes the classification of equipment information. With the basic information of equipment, it also proves that the method is valid in the equipment information integration. Therefore, it can provide theory support for resolving the semantically heterogeneous problem in the information integration of equipment field.

Abstract:Based on the optimization of causal implementation for the lifting schemes and the interleaving mode for sub-band coefficients, this research presents an enhanced low-memory implementation of discrete wavelet transform called the ELDWT (Enhanced Low-Memory Discrete Wavelet Transform). In comparison with the conventional global implementation of DWT, the ELDWT has the advantages that its memory budget is independent of the image height and different DWT filter banks cad be utilized in different decomposition/reconstruction levels. When the difference between the filters’ lengths is greater than two, the ELDWT has lower memory requirement and less system latency than those of the line-based DWT (LBWT). When a 5-level decomposition with the MPEG Default 9/3 filter bank is adopted, the overall memory is reduced by 22.7% in comparison with the LBWT.

Abstract:Fingerprint orientation field describes the essential texture features in a fingerprint impression, including shape, structure and direction. A representation scheme is introduced to describe the local orientation field around a minutia, so as to describe and discriminate different minutiae based on the neighbor texture information. On poor-quality fingerprint images, especially when heavy nonlinear distortion exists, minutia direction is no longer reliable enough. As a result, it is not effective to align two local orientation field images with a minutiae pair as the reference. An improved alignment and matching method of local orientation field images is proposed, which can achieve much better performance and improve the matching accuracy more clearly. Experimental results show that the proposed method can evaluate the resemblance between two minutiae more effectively.

Abstract:With the help of quantum computation operator, a quantum secret sharing scheme based on polarized single photons is proposed. Efficiency analysis indicates that all qubits can be used in the secret sharing. With the permutation operator and quantum entanglement, the protocol can resist the middleman attack effectively. By using the auxiliary qubit, the protocol can detect the Trojan horse attack with high probability. The extension of the permutation operator shows the scheme which contains n pairs is feasible and applicable.

Abstract:When a large number of samples are being scheduled to run in dozens of computers, it is low in efficiency and easy to make mistakes for manual operation. Thus, an automatic tool for deploying and scheduling tasks can improve the analytic simulation’s execution efficiency. The Monte Carlo simulation and the Particle Swarm Optimization algorithm simulation are two kinds of classical analytic simulations. This research introduces the rationales and key techniques for the multi-sample scheduling tool based on both simulations, which can be generally and widely used in resolving varieties of problems about the automatically deploying and scheduling of simulation tasks.