Abstract:A method is propounded in this paper to update finite element model of high pressure spool in aero engine to describe the non-linear contacting surfaces exactly. Firstly, the non-linear model is founded based on the linear model in rod fasten rotor. Secondly, it is posed as the minimization of an error function defined in the time domain. The minimization is carried out by a novel particle swarm optimization method based on adaptive cloud distributing model, which treats its different particles distinctly. Finally, the method has been tested through a simulated function model and finite element model of high pressure spool. The performances of the proposed adaptive algorithm are effective in comparison with other related algorithms.

Abstract:In order to investigate the influence of different cooling methods on cooling efficiency of center cone in turbo-fan engine，the physical models of components after low turbine are established in the paper, and distribution of temperature in cone is simulated and calculated by coupling method of fluid and solid, the study focused on the influence of cooling flux ratios and injection angle when different cooling methods are adopted. The results show that importing air to cavity cools cone efficiently except for middle section before double row holes，improving flux ratio in a certain range can improve the cooling effectiveness; compared with cooling by importing air to cavity, method that compound importing air to cavity and full coverage film cooling can reduce the temperature on middle section before double row holes by 40 percent while the flow ratio remains constant.

Abstract:Simulation of inlet distortion is carried out by using a method of the Insert board to test the stability of inlet／engine matching work of a domestic engine, and five operation states, i.e., nlcor=70％, 75％, 82％, 89％, 96.7％ are selected. The numerical simulation results and the test results of steady total pressure distortion and Δσ0 of the inlet are contrasted and analyzed. The steady total pressure distortion obtained by calculation is the same as that obtained by test. When nlcoris constant,Δσ0is non-linear with the change of the height of the insert board. When the height of the board is above 30％, Δσ0 begins to soar. When the height is constant,Δσ0 is non-linear with the change of nlcor. nlcor changes dramatically at value 82％.

Abstract:In order to solve the problem that it is difficult to evaluate the equipment operational availability in development phase, an integrative evaluating method that combines experiment design, simulation modeling and regression tree is proposed. The simulation model of single equipment operational availability under two-echelon maintenance support structure is developed by using arena software, the design of input scenario is accomplished by adopting latin hypercube sampling (LHS), the output data of operational availability is obtained through running the established simulation model, and factors that have obvious influence on operational availability are determined by the regression tree. Finally the feasibility of the proposed method is shown by numerical examples.

Abstract:Aimed at the problem in the fault diagnosis task for path planning, a certain fault diagnosis modeling method is proposed based on graph theory, the fault diagnosis task model is simplified, the structural relationship of equipment is represented by adjacency matrix, and the coupled task set is found and merged by using reach matrix. By analyzing and studying the fault diagnosis path planning in depth, two patterns of the fault diagnosis task model are distinguished by containing priori knowledge or not, and the classic depth-first algorithm and the greedy algorithm are improved. The algorithm is applied to the fault diagnosis of surface-to-air missile weapons to plan the path. The results show that the method is feasible and effective, and the fault diagnosis efficiency is improved.

Abstract:Aimed at the characteristic of whole task completion time constraint and single task time window constraint of task allocation in multiple aerial grouping, the time constraint mathematical model in pursuit of maximal task execute efficiency is established. The wastage of group resource in combat is analyzed, and grouping resource capability dynamical renewal model is built so as to make the model adapt to the realistic situation. The circulative Nested-DLS task allocation algorithm is advanced based on nested dynamic list scheduling, in which the dynamic list scheduling selected task and the quantum genetic algorithm chosen best group for the task. At last, the superiority and applicability of this approach are illuminated by using the simulation of campaign assumption.

Abstract:Aimed at the evaluation problem of the missile defense engage schedule chain, in the description of the uncertain and fuzzy information flow parameter by three-parameter Vague value, the information superiority conversion evaluation V-GERT network model is established by the GERT network theory. The basic parameter calculation theorem of V-GERT network is also given. Then the information superiority conversion probability and conversion effect evaluation factor model are put forward. The probability and evaluation factor can be considered as an engage schedule chain measurement to provide a way for the design and optimization of missile defense engage schedule chain.

Abstract:On the problem of the interceptor guidance for air-based ballistic missile defense during the boost-phase, firstly, the time optimal control model is established, and the model constraints and controls is discussed combining the characters of the air-based ballistic missile defense task; secondly, the method for the interceptor feasible trajectory computing is put forward based on the Virtual arc; then the iterative computing method for trajectory-Shaping guidance law is designed based on the factors, viz. minimizing the interceptor flying time, minimizing the interceptor flying time distance and maximizing the confluence angle between the interceptor and the targeting ballistic missile at the hit point; lastly, the efficiency of the model and the arithmetic is validated by simulation.

Abstract:Aimed at the poor performance of short term prediction of navigation satellite clock error, a method is proposed for prediction of satellite clock error based on the least square support vector machine (LS-SVM) and artificial fish-swarm algorithm (AFSA). To avoid the man-made blindness and enhance the efficiency of online forecasting, penalty parameter and kernel bandwidth parameter of LS-SVM are optimized by artificial fish-swarm algorithm with a rather good ability of global optimization based on AFSA model. The clock data of four typical GPS satellites are chosen and respectively used in three models to forecast short term clock error. The results show that the accuracy of LS-SVM based on model is superior to the other models, especially in the field of rubidium clock; the error is less than 0.5 ns, and running time is in 5 minutes. The work provides a new way for short term prediction of satellite clock error.

Abstract:Aimed at the difficulty, in the micro-Doppler characteristic extraction, caused by the Doppler frequency produced by high-speed trajectory movement of space target to which the micro-Doppler frequency is added, a method is proposed in this paper based on EMD algorithm to achieve translational motion compensation accurately and extract micro-Doppler characteristics. Firstly, the micro-Doppler effect of space spinning target in narrowband radar is deduced and the influence of translational motion on micro-Doppler is analyzed. Secondly, the radar echoes are decomposed into a series of intrinsic-mode functions (IMFs), and the EMD algorithm is used to decompose the instantaneous frequency of the IMFs. The translational motion compensation can be achieved by judging the translational frequency shift component and analyzing the power of IMFs. Finally, the micro-Doppler curves are separated and the micro-motion features of space target such as spinning frequency are also obtained based on the EMD algorithm. Simulations show that the proposed algorithm is feasible and effective.

Abstract:RCS of ballistic missile in the boost phase is the key information to missile early warning. In this paper, the trajectory simulation in the boost phase is built up based on the missile dynamic characteristics. A quasi-static method in conjunction with the method of moment is adopted to calculate dynamic RCS of missile in the boost phase. The missile attitude variations are obtained compared with the static RCS results of all incident angles. Finally, the original data is processed by using N point reduction method to get the joint distribution of mean value and variance of dynamic RCS, through which the trajectory characteristics are shown.

Abstract:Software fault tolerant technique is a means used to guarantee the high reliability and high credibility in systems. This paper proposes a checkpointing-based task recovery mechanism on the VxWorks operating system. Three methods are adopted to solve the checkpointing-based task recovery problem through analyzing the contents of checkpoint files in VxWorks: the variation of memory address is solved based on the active management of pre-allocated memory; the system kernel object pools are built to realize the recovery of kernel object supporting the synchronization and communication between multi tasks; and the task recovery middleware in user layer is designed to achieve the checkpointing setup and task recovery. Finally, the prototype system based on VxWorks and PowerPC is designed and the results show that the use of the checkpointing-based task recovery mechanism can save the task key information correctly and guarantee the validity and consistency of the task recovery.

Abstract:Remote-target detecting and isolation between transmitter and receiver are the problems that need to be solved when FMCW SAR is applied in high-altitude slow-speed airborne platform. A signal model of inter-pulses interrupted frequency-modulated continuous waveform (IPIFMCW) is proposed in consideration of the features of high-altitude slow-speed airborne platform. The imaging of high-altitude slow-speed airborne SAR is realized through the gating signal with different carrier frequency to modulate the transmit signal to obtain long inter-pulses interval and shifting the mixing echo of sub-pulse in fast time domain to get wide-band signal. Compared with the FMICW theory, the results show that IPFMICW not only overcomes the problem of isolation between transmitter and receiver, but also fulfills the need of remote-target imaging for high-altitude airborne SAR and avoids range ambiguity. Finally, the imaging of high-altitude slow-speed airborne SAR based on IPIFMCW signal is realized through frequency scaling algorithm (FSA).

Abstract:The ideal minimum energy routing is analyzed in this paper. Minimum energy routing algorithm is presented based on probability reaching link PRLMER by utilizing geographic location information, and considering link reaching probability to realize minimum energy routing. The simulation results show that PRLMER lowers the consumption of the end-to-end energy greatly while affording higher packet delivery ratio in comparison with GPSR.

Abstract:PECT is widely used in aviation, nuclear power, etc. In this paper, PECT integrated with Gradient Magnetic Field Measurement (GMFM) is proposed particularly for imaging of hidden corrosion in this paper.Simulation results indicate that GMFM is advantageous in detection of defect edges, which has potential benefit for defect imaging. A PECT system has been built. Signals are obtained when the PECT probe scans over a hidden corrosion, and defect images are derived in post processing. It has been found from the experimental results that the GMFM-based PECT has advantages over conventional PECT in terms of high sensitivity and efficiency in defect imaging of hidden corrosion.

Abstract:To solve the damage problem of low slow small target caused by laser irradiation, a model of low slow small target (LLST) irradiated by a 1.06 μm slant path transmission laser is established. Through simulation calculation using the model, the paper presents the transmission rate vs. the zenith angle and the altitude in various atmospheric visibilities and the normalized power density vs. time in different zenith angle. The factors of the normalized power density are analyzed, such as the atmospheric visibility, the zenith angle and the altitude. Furthermore, the best condition that the zenith angle can be determined in the process of the laser defense low slow small moving target, the surface energy is the largest in the irradiation time.

Abstract:Aimed at the problem of the secure access to the data in cloud storage, an efficient and secure model of cloud storage which supports the access of multi-user in hierarchy and adopts the cloud server as the central point is proposed. This model is used to design a semantic searchable encryption with the use of elliptic curve cryptosystem, and the use of the model improves the accuracy of the result by the keyword's degree of correlation and the order preserving encryption. Through the combination of proxy encryption, user access control list and user-data access control matrix, this model can satisfy the access of multi-user in hierarchy and efficiently solve the management of the dynamic user' s private keys. In the end through the analysis and comparison of the security and efficiency, the results show that his new model is feasible.

Abstract:Method of moment (MoM) expends large computer resource when calculating radiation and scattering problem of large target. The adaptive cross approximation (ACA) algorithm is applied to compress the distant field rank-deficient sub-matrices of the impedance matrix through linear algebra manipulations, which reduces memory needs and calculation complexity in MoM when computing electrically large problem. The RWG (Rao-Wilton-Glisson) triangle spaces are grouped according to the Non-Uniform Rational B-Splines (NURBS) spaces by means of NURBS modeling method. The grouping method is designed to realize the ACA algorithm based on MOM, which could make the subgroups more regular and clearer on the boundary line. Numerical examples are performed, the results show that this method can be the same with MoM in computation precision, and simultaneously the memory and compute time are reduced by this method. RCS (Radar Cross Section) of electrically large metal missile calculated by using this method is in good agreement with the result calculated by the commercial software, which shows that the algorithm is accurate and effective.

Abstract:An adaptive acquisition algorithm of PN codes is presented based on SNR control because the acquiring SNR is time-varying in complex electromagnetism environment. The use of the algorithm can reduce the mean code acquisition time and the virtual alarm probability. Based on the performance analysis of the sliding correlation method, an adaptive scheme is constructed to achieve the goal to set the time of integral and the threshold in SNR control, and the influence of the above parameters on the performance of acquisition is studied as well. Simulation results show that the method can reduce the mean code acquisition time by 50% when SNR>-3 dB, and reduce the virtual alarm probability by 5%~35% when SNR<-7 dB, the method meets the design requirements of acquisition properties under the SNR change environment.

Abstract:Slag and fly ash are used in the fabrication of GC, and NaOH and Na2CO3 are used for slag and fly ash activation, then highly fluidized C30 Geopolymer Concrete (GC) is prepared. Φ100 mm SHPB apparatus is improved by using the pulse shaper technique, based on this, dynamic splitting-tensile tests are made, and the energy properties of GC under impact loading are analyzed. The results indicate that the incident pulse, reflected pulse, transmitted pulse energy and the energy absorption are increased with the rising of average incident pulse energy rate, but the increasing rate will gradually decay, the general law can be described as quadratic polynomial relationship. With the rising of average incident pulse energy rate, the damage level of specimen will be more serious and the comminuted area shaped like an triangle on the loading end will become larger, moreover, the comminuted area close to the incident bar is greater than that close to the reflected bar. GC and ordinary Portland cement concrete (OPCC) exhibit incident pulse energy rate dependency, but the increasing rate of energy absorption of OPCC almost keeps constant with the rising of average incident pulse energy rate, and the general law can be described as linear relationship.

Abstract:After the study of Matching Pursuit (MP) based signal sparse decomposition, analysis of structural property of the over-complete atom dictionary used in signal sparse decomposition is made, this paper creates frequency atom dictionary after seeking out centric position, dichotomy control of positional parameter based signal sparse decomposition algorithm is presented, applying to improved MP algorithm based on centric position parameter . The calculating speed of the algorithm in this paper increase by about 36 times compared with MP algorithm .This algorithm can reduce the computation complexity and improve the precision of sparse decomposition. Finally the simulation data processing verified that the proposed algorithm is effective and corrective.

Abstract:For any postive integer n, the famous Smarandache function is defined as making m!/nthe largest positive integer m. In the paper, the dual function ∑d/ns*(d) is studied and a calculation formula is given by using an elementary method.