Abstract:Maze composition cooling structure of combustor is a kind of novel cooling structure incorporated the strong points of impingement, convection heat exchange and approximately perspiration cooling. It possesses the advantages of impingement, convection heat exchange and mat wall cooling structure, so it is an ideal cooling structure. On the basis of investigating cooling mechanism of this cooling structure and from the practical point of view, tile maze cooling structure is designed by taking the modification design of combustor in active service engine for example. Meantime heat exchange analysis and calculation of wall temperature also are made. Preliminary investigation shows that the cooling performance of this cooling structure is superior to that of full air-film cooling structure.

Abstract:Taking the fourth and the sixth stage blades of a certain aero-engine compressor for example, the blade static frequencies and the kinetic frequencies in some given revolutions are first calculated in consideration of the effects of both temperature corresponding to compressor blade working state and blade twist. Then, the relationship between the static frequency and the kinetic frequency is obtained by fitting the calculated results. Compared with the traditional relationship, the present relationship reflects the effects of both temperature and blade twist. By this relationship, not only the kinetic frequency can be obtained at any blade velocity, but also the result is close to the real one correlating to the practical blade working state.

Abstract:Maintenance cost estimating methods for aircraft can be sorted into basic method and normal method. The article analyzes the application area of these methods and contrasts the advantages and disadvantages of these methods. The article also discusses the problem in this field and forecasts the development. It can provide a useful methodology for estimating maintenance cost of aircraft.

Abstract:From the point of view of the optimization in fuzzy control, the idea of variable domain and the concept of flex factor are discussed. At the same time the preponderance of variable domain and the relationship between the quantization factor, the proportional factor and the flex factor are explained. In addition, the method of selecting the two flex factors is analyzed in detail. Another new intelligence control means - fuzzy logic adjusting PID online based on variable domain on self-adaptation is realized by putting the idea of variable domain into fuzzy PID. The research is based on some complicated nonlinear system, and the result of simulation is predominant.

Abstract:This paper puts forward a new method of evaluating the multi-type missiles network fighting deployment effectiveness. First, an evaluation index system is established, then D - S evidential combination algorithm is applied to dealing with the evaluating data from many experts. Based on the achieved decision - making matrix, entropy technique is applied to modifying right index given beforehand, and then combined with decision - making matrix the evaluation result is obtained. Finally an example is given to prove the usability of the model.

Abstract:Because the measure angle error of ARM greatly affects the hitting precision and killing probability, for the ground -to-air missile there exist the nearest safe distance and time of closing the radar when firing the ARM attacker. Based on this, the paper is the first to put forward the concept of the best - firing region when the ground-to-air missile firing the ARM attacker. The sectional views of the vertical and horizontal best-firing regions under two different speeds of ARM assaulting are obtained through the simulation model.

Abstract:Concepts about bridge node and loop tangency are proposed. The principle of the loop shrinkage of the signal flow graphs is deduced from the point of view of the equivalence of node split. Four general shrinkage rules are discussed. The paper extends the Mason signal flow graph theory and provides a method for simplifying signal flow graph. At the same time, some examples are given.

Abstract:Based on catastrophe theory, catastrophe evaluation is used to study the effectiveness evaluation method of maintenance support system of air force communication equipment, and compared with the results of AHP, the conclusions are accordant on the whole. This study provides a new method for effectiveness evaluation of maintenance support system and a quantitative basis for decision.

Abstract:A mathematical and physical model of electron-gas collisions is constructed. The experimental observation and theoretical analysis demonstrate that light emissions of a carbon nanotube-field emission display (CNT-FED) at different vacuum levels are mainly caused by electron bombardment on the phosphor. Light emission of the phosphor, excited by ultraviolet (UV) light derived from gas discharge, is not found even if the vacuum level is very poor. If vacuum level is too poor, a large amount of gas ionization will reduce the electric potential difference between the cathode and anode, so electrons are not emitted. The numerical calculations for the mean frequency of electron-gas collision indicate that the product of gas pressure and distance between the electrodes (pd) is a better parameter to characterize the effect of vacuum level for FED than gas pressure only, and when the distance between the cathode and anode is increased, the vacuum level must be improved to obtain the same effect.

Abstract:The principles of Independent Component Analysis (ICA) and factor analysis are given, and that the essence of ICA is factor rotation is presented. The analyses show that conventional factor rotations such as Varimax and Orthomax are equivalent conditionally to the early kurtosis-based estimate method for ICA presented. A Varimax-based method for ICA is proposed in consideration of all non-Gaussian sources even mixed signals with sub-and super-Gaussian distributions are included. Experimental results show that the novel method is simple and efficient when the mixing matrix is sparse.

Abstract:Node - state information is an important factor in QoS research. The Probability Mass Function (PMF) of delay at each node is taken as state information and a filter algorithm is proposed and used for normalizing it. And the simulation proves that the PMF is still a normal distribution function through scheduler. Experimental results and theoretical analysis show that the method is effective and feasible in simplifying the network calculation and improving the stability of node - state to meet the corresponding statistical guarantees.

Abstract:Based on the analysis of the traffic attribute of softswitch system, this paper introduces a general traffic model of softswitch, i.e. respectively taking three arrival processes--- Bernoulli process, Poisson process and Pascal process into consideration. Based on this, a queuing system status diagram of softswitch system is given. And the formula of calculating softswitch traffic is deduced, which provides theoretical bases for the design and analysis of a softswitch system.

Abstract:In the process of static parameters detection of artillery pipe, it is very important for the parameters of rifling to be recognized and extracted. The paper analyzes in detail the measuring principle, and also introduces the measuring process of the system. An algorithm is also developed based on class variance after a great number of cannon barrel images are analyzed. The verification in actual measurement shows that the algorithm satisfies the measurement precision indices and is in common use. Finally, analysis of the system and experiment result for uncertainty is given.

Abstract:In view of the problem that special FFT processor fail to satisfy the need of the complicated high - speed real - time signal processing in modern radar, four designs of high-speed FFT are presented. Some FFT algorithms are analyzed and compared with each other in speed, resource and complexity, Radix 4 algorithm is selected and CORDIC algorithm is utilized to produce rotation factor whose number and word length are configurable. The validity of the design is validated by the performance analysis and the hardware implementation.

Abstract:A kind of Turbo concatenated code is presented which uses two same degree distribution pairs of irregular LDPC codes as the two component codes in Turbo structure. Simulation results show that at low SNR , the new Turbo concatenated code is superior to PCGC code, irregular LDPC code and Turbo code in performance.

Abstract:A fast back projection (FBP) algorithm is proposed based on back projection (BP) algorithm, and the imaging results of spot target and multi-spot targets are received by applying both FBP algorithm and BP algorithm to UWB SAR. Through comparing the results, the speediness and validity of the fast back projection algorithm are testified.

Abstract:The optimal or near optimal quaternary self-orthogonal codes of dimensions 2 and 3 are investigated in this paper, and the relations between the optimal self - orthogonal code length, dimension and the minimum distance are found. By means of constructing the generator matrices of such optimal or near optimal self - orthogonal codes, the optimal codes of dimensions 2 and 3 that achieve the Griesmer bound are determined. Especially, the weight polynomial of the optimal or near optimal quaternary self - orthogonal codes of dimensions 2 is obtained.

Abstract:This paper proposes a new mathematical analysis model for computing the average packet delay of IEEE 802.11 protocol. This analysis is valid by comparison with the simulation result based on OPNET. The proposed analysis verifies that when RTS/CTS mechanism achieves lower packet delay, with respect to the basic access mechanism, it is of great importance to the rational use of RTS/CTS mechanism and the notable increase in the performance of IEEE 802.11 WLAN.

Abstract:A simple and effective iteration stopping criterion for image smoothing model of anisotropic diffusion is proposed. This criterion includes a rule for selecting optimal stopping time so that the correlation of filtered image with noise is minimized. This novel method can be used in many kinds of smoothing filtering modes based on PDE without the need for additive knowledge about image noise. Experimental results have demonstrated that, by using the proposed method, satisfactory filtered images can be effectively obtained.

Abstract:Using band-pass filtering characteristic of Morlet wavelet in frequency area, a method for identifying frequency of vibration systems directly on scalograms by changing frequency bandwidth of Morlet wavelet is studied. The advantages of this method are simple and easy in use. The circumstances in accordance to existing serious noise in real test data and identifying closely mode of vibration systems are simulated. The results of simulation show that the method is feasible and effective.

Abstract:In order to design effectively spall-resistant steel panels for a certain airplane underground structure, a stress historical algorithm is presented for concrete within underground structures under blast loading based on one-dimensional theorem of stress waves within layered structure. The numerical example shows the stress histories within the concrete and steel, and brings to light the mechanism of spall-resistant steel panel.

Abstract:In this paper, the energy level splitting of the d orbits of Cr2+(3d4) in tetrahedron crystal field (Td point group) is calculated and analyzed by using the point group theory. In consideration of the static state Jahn-Teller effect, the energy level will farther split. First of all, when the five-dimension reduction representation with the five d orbits wave-functions as the base functions is converted to an un-reduction representation, the energy splitting in tetrahedron crystal field can be obtained. Because of the static state Jahn-Teller effect, the tetrahedron symmetry will distort and transform to tetragonal symmetry, at the same time, Td point group will transform to D2d point group, which makes orbits further split. So the energy splitting in tetragonal crystal field can be obtained when the reduction representation with the split orbits wave-functions as the base functions is converted to the un-reduction representation of D2d point group.

Abstract:This paper discusses the theoretical models and numerical experiments of parallel iteration methods for solving non-linear differential-algebraic systems. Dynamics iteration methods are used to split the differential-algebraic equations, and the numerical experiments are selected to test the parallel iteration methods on Dawning 3000 Super Server Systems. The result shows that the iterative methods can implement parallel availably and possess a superior accelerated ratio. It is testified that the dynamics iteration methods possess immanent parallel in theory.

Abstract:With the wide application of Linux and Apache, business organizations have become more aware of open source software and its benefits. Many open source products are price competitive, as well as feature competitive with their commercial counterparts. That makes them highly attractive to organizations building their system, especially when the use of commercial solutions may imply large license costs. The purpose of the paper is to introduce open source to more people and let them understand the open source software. The paper sets out to analyze the open source applications in order to identify the advantages and disadvantages of the open source applications so that people can have a better understanding of the open source and gain the benefits from it.

Abstract:A method of reduction of decision rulers is proposed based on rough set and fuzzy set. The continuous attributes in the decision table are justified using the proper fuzzy membership functions and division method. The fuzzy similar matrix of the attributes is constructed by means of the fuzzy degree of nearness and the indiscernibility relation in classical rough set is generalized to the fuzzy similarity relation. And a decision rule reduction algorithm is presented based on fuzzy-rough set model.

Abstract:Modeling idea and the mathematical models of fuel allocation process are introduced in this paper. In modeling of fuel allocation process, the mathematical models are built for all steps of fuel allocation process respectively, among which the iterative model solves the time optimization transportation problem effectively. Practice proves that the models built are reasonable and effective.