Abstract:This paper deals with the exact-landing of aerocraft and discusses a kind of the technique of optimizing the orbit-alteration for the exact-landing of aerocraft by using evolution-algorithm, based on single-pulse on orbital apogee and common single-pulse.

Abstract:A basic idea of a quiet wind tunnel is described. A supersonic quiet wind tunnel(SQWT-120) is designed and built. SQWT-120 designed Mach number is 4.0, the nozzle outlet diameter is 120mm, Re is 0.46～1.78×10⁷and the operation duration is 6-60 seconds. The conclusions of calibrations demonstrate the actual flow Mach number is 3.8, ΔM/M is ≯±1.2% between x=160mm and x=438mm. The unsteady pressure disturbances are not larger than 0.1% before x=450mm, the operation time is 15s. The results show that the wind tunnel can be used to study the steady flow and unsteady flow.

Abstract:The damage-mitigating and life-extending control (DMLEC) based on multiobjective optimization (MOO) is presented by DMLEC policy analysis and synthesis. The progress of solving DMLEC policy by using nonlinear programming is analysed which combines with the dynamics modelling, the structural analysis of turbine blade and the damage modelling of a certain liquid-propellant rocket engine.Then, the start-up process of the LRE under the control of DMLEC is simulated. The result indicates that the damage of blade is mitigated and the service life of LRE is extended considerably while the system performance is only debased a little.

Abstract:Perhydropolysilazane, a preceramic polymer for silicon nitride ceramics, was synthesized by the ammonolysis of dichlorosilane and characterized by FT-IR, GPC, TG, XRD and elemental analysis. The main backbone of the as-synthesized precursor oligomer was［SiH₂NH］_n, with a number average molecular weight of 106 and a weight average molecular weight of 178. The cured precursor polymer was converted into brown ceramic powder after pyrolysis at 1000℃ in nitrogen atmosphere, and the ceramic yield was 78wt%. X-ray patterns showed that the main phases of the polymer-derived ceramic product at 1400℃ in nitrogen atmosphere were α-Si₃N₄ and some free silicon, and the empirical chemical formula for the product was SiN_1.036O_0.060C_0.028 by elemental analysis. After further treatment at 1600℃ in nitrogen atmosphere, extremely weak diffraction peaks for free silicon and intense peaks for α-Si₃N₄ were observed by XRD patterns, however, there was no phase transition from α-Si₃N₄to β-Si₃N₄all along.

Abstract:In order to determine the contents of chlorine in the fume of warships on fire, the method of AgCl turbidity is improved by adding appropriate dispersing agent and surface active agent such as sodium dodecyl benzene sulphonate (DBS), poly(vinyl alcohol) (PVA) and twein-80. The results show that the stability and sensitivity of the system are improved, and the detection limit is decreased from 3.5×10^-1mg/L to 3.1×10^-2mg/L. The improved method has wide linear range and high reproducibility.

Abstract:A 3D FE model of the cracked aluminum plate bonded by carbon fiber composite is proposed and validated when the plate is with biaxial loading. The efficiency of composite repair is investigated too. The effect of composite patch, ply sequence, length of patch and the ratio of loading on the stress intensifying factor (SIF) of the cracked plate is studied. It is shown that there exists coupling effect between the two applied loading and the efficiency of the composite repair is affected by the ratio of loading. The SIF of plate is reduced when the tensile loading is applied parallel to the crack while the SIF is increased when the compressive loading is applied perpendicularly to the crack.

Abstract:An automatic fingerprint identification system (AFIS) includes two stages,i.e. registration and authentication. At the atregistration stage, most AFISs store multiple template fingerprints of the same finger per user. When authenticating, the input fingerprint is compared with these multiple templates. This paper proposes merging features of multiple template fingerprints.Only the merged template is stored in the template database. When authenticating, the number of templates with which the input fingerprint is compared is decreased, thus the authentication is sped up. At the same time, it helps to improve the recognition accuracy so that the merged template contains more features than a single template. Experiments show that our method can achieve improved system performance.

Abstract:Fault containment is proposed to construct a survivable kernel of the network security device based on the IBM virtual machine. This is accomplished by setting up an efficient resource manager to supply physical resources to the virtual machine and to balance other performance requirements. Software and hardware fault containment technology is used to protect against system attacks, and avoid a system breakdown from a single fault. Model and tests prove this idea and the overheads are almost negligible.

Abstract:3D SPECK compression of multispectral remote sensing image is presented, which is based on integer wavelet transform (IWT) by analyzing the characteristics of transformed wavelet coefficient. By the method the zero-tree coding of the compression of wavelet transform is extended to the compression of multispectral remote sensing image. Integer wavelet transform is applied to reduce the spatial decorrelation, and DCT is applied to reduce the inter-band correlation. 3D SPECK is used in processing the transformed wavelet coefficient. The results of experiment indicate that hardware is easier to realize, the time of coding and decoding is less, and the requirement of EMS memory is lower.

Abstract:Based on the signature analysis of wideband echo from the ballistic missile, a novel method is proposed, which can extract the features of the moving target. High-resolution radar echo is processed by STRETCH technique and range profiles are obtained. By observing the periods of the target length variant, the frequency of nutation is deduced. According to the location of the rangeprofile in imaging windows, the range between the radar and target is estimated. After the range shift between the two adjacent rangeprofile provided by envelope correlation algorithm,the target velocity is estimated by computing the time difference between the adjacent two mixers. Simulation results show the effectiveness of the method.

Abstract:An efficient VLSI architecture for two-dimension DWT is proposed and illustrated in detail for the CDF9/7 wavelet transform. The improved lifting scheme is adopted to reduce the critical path delay. Coefficients of the multipliers are transformed into CSD forms and then the multiplications are substituted by shift-add operations. The row transform and column transform are running simultaneously and pipeline design is used to optimize the architecture. This architecture is implemented through behavioral VHDL. The results are identical with those of the software simulation, and thus the validity of this architecture is proved. Compared with other architectures, this one has the advantages of faster computation time and almost 100% hardware utilization.

Abstract:The fundamental theory of direct digital synthesizer(DDS) and the spectrum of the output signal under the ideal conditions are introduced firstly. Then the error signal in engineering is analyzed. The output signal background spurious brought about by phase truncation and digital amplitude are explained from the angle of the theory of signal and system, and in the end the effects of D/A's none ideal characteristics and the clock's phase noise are expounded.

Abstract:Frequency-agility amplitude weighting method is a common one to suppress the angular glint. The amplitude weighting method based on ABA (amplitude-based angle) processing is developed to suppress the angular glint. Firstly, the single pulse angle measuring result is restricted to certain extent. Then the amplitude weighting method is applied to each pulse's result. Computer simulation proves that this new method is much better to the common amplitude weighting method in suppressing the angular glint under all kinds of SNR conditions.

Abstract:It is a important task for imaging scheduling to acquire more image data of good quality by making rational and efficient use of the remote sensing satellite. To solve this problem a scheme is presented, which includes building satellite imaging time ordered acyclic directed graph, evaluating different imaging path according to multicriteria, and obtaining the optimal imaging path with time ordered multicriteria shortest path algorithm. Theoretical analysis and experimental results show that by using the scheme, multiple optimal pareto paths can be obtained within acceptable time, and better scheduling can be guaranteed.

Abstract:A new method of hiding images based on fractional Fourier transform (FRT) is presented. With this method, the FRT of several images with different fractional orders are recorded on one plate. And another fractional fourier transform accomplishes the hiding after adding the phase encoding. In order to reconstruct the encoded images, several FRT with certain orders and particular phase encoding are needed. That makes the encrypted images more difficult to decrypt even by an authorized person.

Abstract:Finding the right features is a key part of a pattern recognition system. This paper presents a linear feature extraction algorithm which research the optimal pattern centers and projection in Fisher's criterion by genetic algorithm(GA).And then the new algorithm is used in the range profile features extraction and recognition. Experiments show that the new algorithms are more effective than LDA in Fisher's function value and classifying results.

Abstract:The pattern synthesis algorithm for arbitrary arrays using adaptive beamforming method is discussed. An improved iterative linear constraints least square algorithm is presented. The new algorithm exhibits numerical robust and can be used with random sparse arrays. The algorithm finds the best attainable pattern with the given array if the pattern specifications cannot be met. Numerical examples are presented to illustrate the performance of the algorithm.

Abstract:Electromagnetism characteristics of large complex target are analysed by combining multilevel fast multipole method and ILUT preconditioner. We must solve a linear system when solving electromagnetic integral equation by moment method. Multilevel fast multipole method is used to fast calculate the matrix-vector product when we solve the linear system by iterative method. ILUT preconditioner is used to reduce the prove condition number on the linear system and speed up the convergence iterative method. Numerical experiments show the robustness of our method.

Abstract:A technique based on the combination of Fourier pseudospectral time-domain method (PSTD) and PML absorbing boundary conditions is widely used to simulate the scattering and propagation problems. However, one of the known disadvantages of this method is that it requires a uniformly distributed spatial grid-set along each orthogonal direction. But its accuracy is lower when applied to the objects involving the curved boundary or thein dimensions are not commensurate with the cell size. The PSTD method involving space transformations (TSNU-PSTD) alleviates this limitation. The CFS-PML is implemented in the PSTD and the TSNU-PSTD algorithm combined with the CFS-PML has been applied to model ground-penetrating radar (GPR) application involving objects in a large-scale lossy half space, and the results are compared with the FDTD. Numerical simulations show that it can achieve a satisfactory result with a grid density of only 3.0 nodes per minimum wavelength, and can simulate the scattering of curved objects in large-scale lossy media efficaciously

Abstract:In order to detect the turbopump fault short of fault samples, the spectrums of turbopump vibration signals were analyzed, and the frequency band energy ratio was selected as the fault feature of those signals. After SOM competitive learning theory and U matrix description of clustering results were discussed, the frequency-band-energy-ratio-based SOM algorithm for turbopump fault detection is presented, and the selection of the best matching unit (BMU) and the adaptive upgrade of their weight vectors are also realized in this algorithm. With a liquid rocket engine (LRE) historical test data, this algorithm is validated. These results show that there is only one class when the algorithm is used to healthy turbopump vibration data, and the distance between the neighboring neuron is less than 0.1; while there are two or more classes when the algorithm is used for faulty turbopump vibration data, and the distance between the neighboring neuron is greater than 0.1. Therefore the algorithm can effectively detect the turbopump fault.

Abstract:The false alarm of the BIT based on model in the mechatronics control system is studied. Firstly, the information uncertainty of the BIT system and the reason of BIT false alarm are analyzed. Then, the BIT system is designed by the application of the optimal UIO(unknown input observer). It is robust to the information uncertainty, and can decrease the false alarm. Finally, the experimentation on the BIT system of stabilization and automatic pointing and tracking platform is made. The result shows that the analysis is correct and the method is effective.

Abstract:It is necessary to get the dimension of re-constructed phase space before calculating the chaotic statistical. characteristics. Six methods are offered which are the measurement of the on unaltered maximal characteristic value, the measurement of changeless geometry mete, the measurement of false nearest neighbors, the measurement of minimum prediction error, the measurement of minimal Shannon entropy, and the measurement of the experience evaluation. An engineering case is given to explain the application of the measurements of the unaltered maximal characteristic value and minimal Shannon entropy.

Abstract:According to the characteristics of the process of the model project, the risk management decision model of the model project is presented. Some essential risk factors of the project duration such as activity overlapping, activity iterations, uncertain activity durations and non-consumable resource amount are integrated into the decision model. Considering the characteristics of the model, a simulation optimization method based on adaptive genetic algorithm is proposed. A case study shows that the algorithm is beneficial.

Abstract:Promoter identification is an essential task in the research of transcription regulation, but computational prediction of promoters has been one of the most elusive problems despite considerable effort devoted to the study. A new prediction algorithm based on the combined features for E. coli σ⁷⁰promoters is proposed. According to their location, all promoters can be classified into two classes: promoters in non-coding regions and promoters in gene regions, and will be processed respectively. In each region, the features of primary sequence，including 1 content feature、5 signal features and 4 structure features, are combined and defined as a 10 dimensional vector, then the vector of combined features is further used by quadratic discriminant analysis to predict the potential promoter regions. The algorithm has been trained and tested on E.coli σ⁷⁰ promoter dataset by the jackknife method. The average prediction accuracies for “non-coding” promoters and “coding” promoters are 86.7% and 82.4%, respectively. The results indicate that our algorithm outperforms most of the existing approaches based on several performance measurements. Furthermore, algorithm framework is extendable and can accept more new features to improve the prediction results efficiently.

Abstract:The conceptual model of mission space is the description of military operation in the real world and other related factors independent of implementation. It is the first abstraction of military activities. The modeling of the conceptual model of mission space is a vital step of the military system development. The main research includes analyzing the current research status and problems, discussing the characters of mission space, proposing and building the two-phase development methodology of conceptual model of mission space based on ontology, which can effectively improve reusability, creditability and facilitate interoperation.

Abstract:The measurement principles are discussed in detail for projectile dimension measurement, based on the analysis and classification of the structural dimensions of special projectiles. According to the practice in the factory, a measuring equipment is set up to measure those dimensions. Two high precision laser displacement sensors and motion controller are introduced to construct this automatic digital measurement system for digital inspection and evaluation of the key dimensions. Actual application shows that this system can effectively improve the projectile dimension measurement precision and give the error distribution. Testing result shows that the system measurement error is less than 10 microns for internal/external diameters and 100 microns for the external length. Hence the measurement system can guide the machining processes and helps to control the product quality.

Abstract:How can the organizations form optimum system security technology schemes to reduce the threat caused by vulnerabilities of their information systems is the key problem in information security management field. On the basis of describing the multi-goal decision-making model of the information system security technology scheme, this paper presented a self-adaptive genetic algorithm for security technology scheme of the information system enabling the organizations to choose the minimal-cost security technology scheme that can address the maximum vulnerabilities. And examples are given to demonstrate the validity of the algorithm.