基于改进蚁群算法的飞机低空突防航路规划(英文)

蚁群算法是一种新型的基于群体的仿生算法。采用蚁群算法实现了飞机低空突防的航路规划,为航路规划问题提供了新的解决思路。并对原始蚁群算法进行了改进,提出了保留最优解、自适应选择策略和自适应信息素调整准则,有效地提高了算法的收敛速度和解的性能。最后用计算机进行了仿真,取得了较好的结果。

基于模糊可靠性的飞机结构腐蚀疲劳寿命评定(英文)

腐蚀和腐蚀疲劳大大降低了LY12CZ铝合金的材料性能,严重地威胁着飞机的结构完整性和使用安全。飞机结构失效过程与所受的载荷、材料特性、服役的腐蚀环境等因素有关,由于各因素联合作用,失效过程损伤机理相当复杂,既有随机性又有模糊性。针对目前腐蚀疲劳寿命评估的常规概率方法的缺陷,基于通过对海军航空部队调研得到的飞机实际使用载荷谱,提出更合理、更贴近实际情况的模糊可靠性评估方法。讨论了蚀孔形状比和各模糊因素对结构寿命的影响规律,研究结果表明该模糊可靠性方法可以应用于飞机结构的腐蚀疲劳寿命评估。

Feature Extraction of Symmetrical Triangular LFMCW Signal Using Wigner-Hough Transform

Feature extraction of symmetrical triangular linear frequency modulation continuous wave （LFM- CW） signal is studied. Combined with its peculiar charaeteristics, a novel algorithm based on Wigner-Hough transform （WHT） is presented for the deteetion and parameter estimation of this type of waveform. The initial frequency and chirp rate of each segment of this wave are estimated, and the peak-value searching steps in the parameter spaee is given. Compared with Wigner-Ville distribution （WVD）, Pseudo-Wigner-Ville distri- bution （PWD） and Smoothed-Peseudo-Wigner-Ville distribution （SPWD）, WHT has proven itself to be the best method for feature extraetion of symmetrical triangular LFMCW signal. In the end, Monte-Carlo simulations under different SNRs are earried out, with validating results on this method.

Chirp-Rate Resolution of Fractional Fourier Transform in Multi-component LFM Signal

Distinguishing close chirp-rates of different linear frequency modulation （LFM） signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-component LFM signal were used by discrete fast fractional Fourier transform （FrFT）. Then the expression of chirp-rate resolution in fractional Fourier domain （FrFD） was deduced from discrete normalize time-frequency distribution, when multi-component LFM signal had only one center frequency. Furthermore, the detail influence of the sampling time, sampling frequency and chirp-rate upon the resolution was analyzed by partial differential equation. Simulation results and analysis indicate that increasing the sampling time can enhance the resolution, but the influence of the sampling frequency can he omitted. What＇s more, in multi-component LFM signal, the chirp-rate resolution of FrFT is no less than a minimal value, and it mainly dependent on the biggest value of chirp-rates, with which it has an approximately positive exponential relationship.

Global exponential stability of Cohen-Grossberg neural networks with variable delays

A class of generalized Cohen-Grossberg neural networks（CGNNs） with variable de- lays are investigated. By introducing a new type of Lyapunov functional and applying the homeomorphism theory and inequality technique, some new conditions axe derived ensuring the existence and uniqueness of the equilibrium point and its global exponential stability for CGNNs. These results obtained are independent of delays, develop the existent outcome in the earlier literature and are very easily checked in practice.

Solving the AKNS Hierarchy by Its Bilinear Form: Generalized Double Wronskian Solutions

通过 Wronskian 技术，一个简单、直接的证明被介绍在双线性的形式的 AKNS 层次概括了两倍 Wronskian 答案。而且由使用一个统一方法，在为它的两倍 Wronskian 形式的 soliton 答案，合理答案， Matveev 答案和 complexitons 被构造。

Research on Radar Emitter Attribute Recognition Method

In order to solve emitter recognition problems in a practical reconnaissance environment, attribute mathematics is introduced. The basic concepts and theory of attribute set and attribute measure are described i n detail. A new attribute recognition method based on attribute measure is prese nted in this paper. Application example is given, which demonstrates this new me thod is accurate and effective. Moreover, computer simulation for recognizing th e emitter purpose is selected, and compared with classical statistical pattern r ecognition through simulation. The excellent experimental results demonstrate t hat this is a brand-new attribute recognition method as compared to existing st atistical pattern recognition techniques.

Track-to-Track Association Technique in Radar Network in the Presence of Systematic Errors

The presence of systematic measuring errors complicates track-to-track association, spatially separates the tracks that correspond to the same true target, and seriously decline the performances of traditional track-to-track association algorithms. Consequently, the influence of radar systematic errors on tracks from different radars, which is described as some rotation and translation, has been analyzed theoretically in this paper. In addition, a novel approach named alignment-correlation method is developed to estimate and reduce this effect, align and correlate tracks accurately without prior registration using phase correlation technique and statistic binary track correlation algorithm. Monte-Carlo simulation results illustrate that the proposed algorithm has good performance in solving the track-to-track association problem with systematic errors in radar network and could provide effective and reliable associated tracks for the next step of registration.

An Improved Local Weighted Linear Prediction Model for Chaotic Time Series

Previous research working on local prediction state with some unsuitable neighbor points （such as false points and pseudo-false neighbor points） are the main source of errors of local prediction and these unsuitable neighbors cannot be eliminated entirely. Therefore, an improved local weighted linear prediction model based on local integrated correlation, which can reduce the influence of the residual unsuitable neighbors, is proposed to predict chaotic time series in our study. Simulation results show that the performance of the improved model is superior to the other local prediction models in the prediction of chaotic time series without and with additive white Gaussian noise.

Adaptive Iterative Learning Control for a Class of Nonlinear Time-varying Systems with Unknown Delays and Input Dead-zone

This paper presents an adaptive iterative learning control(AILC) scheme for a class of nonlinear systems with unknown time-varying delays and unknown input dead-zone.A novel nonlinear form of dead-zone nonlinearity is presented.The assumption of identical initial condition for iterative learning control(ILC) is removed by introducing boundary layer function.The uncertainties with time-varying delays are compensated for by using appropriate Lyapunov-Krasovskii functional and Young’s inequality.Radial basis function neural networks are used to model the time-varying uncertainties.The hyperbolic tangent function is employed to avoid the problem of singularity.According to the property of hyperbolic tangent function,the system output is proved to converge to a small neighborhood of the desired trajectory by constructing Lyapunov-like composite energy function(CEF) in two cases,while keeping all the closedloop signals bounded.Finally,a simulation example is presented to verify the effectiveness of the proposed approach.

Mathematical modeling and analysis of gas torque in twin-rotor piston engine

The gas torque in a twin-rotor piston engine(TRPE) was modeled using adiabatic approximation with instantaneous combustion. The first prototype of TRPE was manufactured. This prototype is intended for high power density engines and can produce 36 power strokes per shaft revolution. Compared with the conventional engines, the vector sum of combustion gas forces acting on each rotor piston in TRPE is a pure torque, and the combustion gas rotates the rotors while compresses the gas in the compression chamber at the same time. Mathematical modeling of gas force transmission was built. Expression for gas torque on each rotor was derived. Different variation patterns of the volume change of working chamber were introduced. The analytical and numerical results is presented to demonstrate the main characteristics of gas torque. The results show that the value of gas torque in TRPE falls to be less than zero before the combustion phase is finished; the time for one stroke is 30° in terms of the rotating angle of the output shaft; gas torque in one complete revolution of the output shaft has a period which is equal to 60° and it is necessary to put off the moment when gas torque becomes zero in order to export the maximum energy.

A Vicious Script in HTML Detection Method Using Judgment Matrix Approach

A vicious script detection method based on statistic is proposed by analyzing the vicious script in the hypertext markup language(HTML).We utilize the judgment matrix approach which is one of the subjective weighting approaches to set the different weights for various statistic methods.Then we make use of the weighted geometric method to perfect the statistic results.Experimental results show the validity of this method.

Trajectory Tracking Control for a GMM Actuator Based on a Heuristic ILC Method

A heuristic iterative learning control （ILC） method is presented and applied to the trajectory tracking control of a giant magnetostrictive material （GMM） actuator. A GMM actuator is used as experimental equipment for micro-displacement trajectory tracking control. The advantage of the presented approach lies in quitting the model of the GMM actuator. The experimental results attest to the high efficiency of the presented method for the micro-displacement trajectory tracking control.

Flight mission modeling based on BDI Petri net

Goals reasoning and management of pilot is a key issue to monitor pilot's behavior and intention. Traditional modeling methods are based on scenarios or situations, such methods will cause the,covering problem due to redundancy and are incapable of depicting interactions among various goals and plans of pilot. Petri net integrated with belief, desire and intention (BDI) theory (BDI Petri net) is designed to solve this problem. Focusing on the BDI theory, goal states of agent are discussed firstly. Belief, desire and intention are modeled by places and transitions based on the Petri net theory. In order to simplify the network, colored token is introduced to depict various states of belief, and the hierarchy transition is applied to model the intention, together with tokens' flow derrionstrating the interaction among various goals and relationship among belief, desire and intention. A search and rescue mission is used to validate the proposed method and the result indicates that the model can be used to monitor goals and behaviors of pilots.

Effect of Altitude Error on Position Precision of Double-Star Position System

The effects of two kinds of methods for obtaining altitudes on the position precision are analyzed, and the error expressions are deduced. Many simulation results show that in the two cases, the effects of the same altitude errors on the positioning precision are identical, and the rules that the two altitude errors affect positioning precision can be expressed as that altitude error has little effect on the east-west position error, but has large effect on the south-north position error.

Fully Differential Leapfrog Implementation for High-Pass Ladder Filters

This paper presents a novel leapfrog signal flow graph (SFG) implementation by fully differential Op amp integrators, which combines low sensitivity, high dynamic range with simple circuit configuration. The direct SFG simulation and leapfrog SFG simulation can yield integrator-based structures likewise, but both of them will lead to higher circuit complexity, noise density and sensitivity. Three Butterworth 5-order high-pass filters with a pass band edge frequency of 1.778 kHz are designed based on different SFGs. From the example, the noise density of the simplest leapfrog configuration is approximately 0.4 nV/Hz1/2 lower than those of the other two in the stop band, and shows the best noise density in the pass band. The sensitivity densities of two types of leapfrog filters are approximately equivalent, while that of the direct SFG simulation filter is much higher. However, the pass band response of the simplest configuration is not as good as those of the other two because of two parasitic zeros (at 708 kHz, -31.6 dB and 1.59 MHz, -20.55 dB) and a parasitic pole (at 4.57 MHz, 45.5 dB).

Study on Quadratic Effect Assessment of Vulnerability of Military Aircraft Under Multiple Hits

Under the conditions of multiple hits and quadratic effects,the aircraft vulnerability assessment method is proposed by means of kill-tree diagram and state transition matrix.Four instances of the quadratic effects are investigated:non-redundant components to non-redundant components,non-redundant to redundant,redundant to non-redundant and redundant to redundant.The application of the proposed method to the calculation of quadratic effects is also studied.

A new fluorescent particle prepared by chemical stabilized phycobilisome

Natural phycobilisomes （PBSs） were isolated and purified from a red macroalga, Polysiphonia urceolata, by multi-step of sucrose gradient centrifugation, and were chemically stabilized by small molecule cross-linker formaldehyde. The stabilized PBSs showed similar absorption and fluorescent properties at room temperature compared to natural PBSs and kept a steady F672/F580 value during more than 3 months of storage in 0.45 mol/L phosphate buffer （pH 6.8） or at low temperature at 77 K. The stabilized PBS migrated as a single band at mild PAGE and in 14-18 h of sucrose gradient centrifugation. All these characters indicated that the stabilized PBSs were stable, soluble, homogenous fluorescent particles with favorable spectroscopic features prepared under present conditions.

The Quenching Problems of R-D Equation

在这篇文章，我们与起始的价值条件 u 认为反应散开是微分方程(x， 0 )= 0 在上[0，一] 并且边界条件 ux + iu = 0 在 = 上 { 0，一 } 慀 ? 污潣潨楬? 瑳灵吗？

A New Deghosting Algorithm with Hypothesis Testing Data Fusion

Eliminating the false intersection (deghosting) is a difficult problem in a passive cross location system. Using a decentralized decision fusion topology, a new deghosting algorithm derived from hypothesis testing theory is developed. It uses the difference between ghosts and true targets in the statistical error, which occurs between their projection angles on a deghosting sensor and is measured from a deghosting sensor, and constructs a corresponding test statistic. Under the Gaussian assumption, ghosts and true targets are decided and discriminated by Chi-square distribution. Simulation results show the feasibility of the algorithm.