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2013 Vol. 39, No. 2

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Guide star selection method applied to ballistic missile
Wang Hongli, Chen Cong, Cui Xiangxiang, Jiang Wei
2013, 39(2): 143-147.
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The present researches on guide star selection methods applied to ballistic missile are not enough, therefore a novel uniformization selection method according to standard trajectory was discussed. By analyzing the impacts of missile trajectory and various flight parameters, and constructing the ‘pseudo celestial sphere coordinate frame', the guide star selection region was determined. The problems caused by fire direction changing or coordinates boundary exceeding were simplified. The guide stars were selected and homogenized on basis of reference points on celestial sphere and the proposed ‘Separation-Magnitude' weighting method. The on-board guide star catalog having better applicability was generated via k-vector index approach, and the efficiency of star identification algorithm would be improved. The simulation results indicate that the method implements simply. Much less guide stars which have better uniform distribution are selected. The elapsed time of star identification is effectively reduced on the basis of the undiminished identification success rate.
Modeling method and vibration characteristics of aero-engine rotor system
Zhang Li, Hong Jie, Ma Yanhong
2013, 39(2): 148-153,163.
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According to the structural and mechanical properties of rotor system on the modern turbofan engine, an investigation about the finite element modeling technology and dynamic characteristics of low-pressure rotor was proposed, based on the finite element method (FEM). The finite element model of rotor system was developed by 2D beam element and 3D solid element separately and the dynamic characteristics were analyzed. Then a principle of finite element modeling, which is called equivalent-disk method, was presented. The equivalent-disk method regards the blades of rotor system as a rigid ring and changes the periodic model into axisymmetric model, which is favorable for FEM software in solving. It can not only keep the structural and mechanical properties of rotor system, but also control the scale of FEM model. The result indicates that this kind of equivalent method can improve the modeling techniques of rotor system on the turbofan engine and it is applicable in engineering.
Dynamic model and flight control method for structure damaged aircraft
Zhong Youwu, Ni Shaobo, Yang Lingyu, Shen Gongzhang
2013, 39(2): 154-158.
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The dynamic model of a structure damaged aircraft was presented, for designing flight control law to ensure flight safety when the aircraft structure damaged partially. After analyzing the dynamic model, the rotational motion of structure damaged aircraft could be decomposed to normal aircraft rotational motion and disturbance motion by structural damage. The control of structure damaged aircraft could be translated to suppress the disturbance motion and uncertainties. A trajectory linearization control method based on extended state observer was proposed to design the robust flight control law. The simulation results indicate that, the flight control system can achieve the decouple control of the aircraft when the right wing lost 15%. And the attitude rate response follows the command well. The control system can endure the uncertainties and disturbance because of structure damage.
Connective boundary's electromagnetic leakage in finite-difference time-domain
Ji Jinzu, Huang Daqing, Huang Peilin, Lu Zhenyi
2013, 39(2): 159-163.
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When calculating target's radar cross section(RCS) with finite-difference time-domain(FDTD), the incident wave was induced using connective boundary. In ideal situation without scattering target, there is only incident wave in total field region and the field in scattering field region is zero. But in practical calculating process, the electromagnetic wave in scattering field region is not rigidly zero because of leakage in connective boundary. In 1-dimensional situation, the leakage was measured by sum of squared electric field. In 2-dimensional situation, the leakage was measured by RCS which acquired by far field transformation of electromagnetic field in scattering field region using equivalent principle. Research results show that time step and incident angle influence the leakage very much. The leakage is small when the time step is near the least step needed for the stable requirement and the incident direction avoids impinging the connection boundary perpendicularly.
Airborne centrifugal refrigerating compressor design and characteristic analysis
Gao Feng, Zhang Xingjuan, Yuan Xiugan
2013, 39(2): 164-167.
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A key technique which is critical to design vapor cycle system (VCS) of the new-generation high-performance fighter aircraft is to develop a super-mini compressor with 50kW cooling capacity. Due to the small air rate flowing through the mini compressor, the designing experience which was used for the massive flow-rate compressor mostly cannot be completely applied to the designing and prediction for the super mini centrifugal refrigeration compressor. In line with the experimental data, design scheme was proposed. The expressions to picture the characteristics of the compressor, such as efficiency and compression ratio, were developed. The analytical calculation results are approximation to the experimental measurements. All aforementioned studies can supply necessary technical support to the design, research and development of refrigeration compressor in VCS adopted in high-performance fighter aircrafts.
Investigation of Whipple shield hypervelocity impact based on scaled test method
Zhang Xiaotian, Jia Guanghui
2013, 39(2): 168-172,177.
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Hypervelocity impact above 7 km/s was investigated based on scaled test method for spacecraft shielding issue. Simulation models of single bumper and Whipple shield were built, both Al-Al impact and Cd-Cd impact problems were simulated under multiple cases. The comparison of test and simulation showed the validity of simulation technique and scaled test method was also verified from the view of simulation. Adaptedness analysis was applied on scaled test method. The result shows that the method is well adapted for the impactor shape and impact velocity, but has larger error for the rear wall of Whipple shield. Failure mode analysis of Whipple shield rear wall indicated that the error was caused by the discontinuity of failure mode. Ballistic limit was investigated finally for Whipple shield above 7 km/s. The result shows that the discontinuity of failure mode in the rear wall cause the bifurcation of ballistic limit curve within this velocity range.
Analysis of storage stability of accelerometers
Xu Dan, Liao Xun, Chen Yunxia, Kang Rui
2013, 39(2): 173-177.
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Based on the finite element analysis(FEA) results of quartz flexible accelerometers, the stability of the scale factor changing with temperature and time was obtained. Then a kind of surface fitting method which was the product type based on least squares, was applied to fit the simulating data and build the accelerated degradation model of the stability of the scale factor. Considering the discrepancy of the product and the error in testing, the model was randomized. Furthermore, the variance was calculated by applying the first-order Taylor expansion, and then the accelerated degradation model with confidence was established. The analysis of the storage stability of accelerometers was conducted on the basis of the model on the condition of storage, and the storage stable period under the given criterion was also calculated. At the same time, the stability evaluation result was also given, that is whether the stability was satisfied with the demand during a period of time under the storage condition.
Realization of model-based fault diagnosis with artificial neural network
Ma Jiming, Wan Wei, Wang Fayan
2013, 39(2): 178-183.
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Based on artificial neural network, a method for fault detection and fault identification was proposed, which can be used during the model-based fault diagnosis (MBFD) process. Firstly, back-propagation (BP) neural network was presented for parameter estimation, combing with the system model, the faults can be detected. Then the adaptive resonance theory (ART2) neural network was used for data clustering, and based on the clustering results, the faults will be identified. Finally, a fault diagnostic system was developed based on BP&ART2 neural network. The presented BP-based parameters estimation method can estimate the parameters under different states accurately, which is important for the fault detection. ART2-based data clustering method can distinguish both the known and unknown fault modes, which is much efficient when diagnosing the system without enough priori information. A brushless direct current motor was selected as the application case, simulation result has proved that the presented method is available to estimate the motor parameters, detect and identify some typical faults, such as brushes position offset and armature open.
Carrier estimation algorithm based on novel hybrid particle filtering
Zhang Hua, Zhang Youguang, Li Guoyan
2013, 39(2): 184-189.
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To reduce the computation complexity and improve the weight degeneracy and loss of diversity about the particles in particle-filtering (PF) based carrier estimation, a novel hybrid particle filter based carrier estimation algorithm was proposed and the method for assigning particle weights of the proposed PF algorithm (PPF) was derived. In this algorithm, the m-order Monte Carlo Markov chain was introduced and the optimal importance function-the posterior importance function was approximated by a weighted sum of non-zero mean Gaussian distributions and the iterative computation of the particles was constrained by the maximum a posterior (MAP) criterion. In non-Gaussian environment, by applying the algorithm in the non-cooperative receiver of the time division multiple address/differential quadrature phase shift keying(TDMA/DEQPSK) data frame in low earth orbit (LEO) satellite communication system, it is found that the efficiency of the particles is improved and the computational complexity is reduced compared to the carrier estimation algorithm based on the traditional PF.
Damage simulation of composite materials based on strain invariant failure theory
Li Xing, Guan Zhidong, Liu Lu, Li Zengshan
2013, 39(2): 190-195.
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Strain invariant failure theory (SIFT) estimates failure in fiber and matrix based on mechanical failure modes, which is suitable to study meso-interaction between fiber and matrix, and to evaluate influence of curing residual stress. Mechanical theory background of SIFT was introduced. Square, hexagon and diamond representative volume element(RVE) model in meso level were established. Transition method between macro and meso level was given. Failure mode and damage evolution criteria were proposed. Based on this theory, mechanical strain amplification factors and thermal strain amplification factors of CCF300/5228 were obtained, open hole tensile performance of CCF300/5228 was calculated, fracture process of fiber and matrix was analyzed. Good agreement between numerical results and experiments is observed, which demonstrates the applicability of this theory.
Aircraft dynamic derivatives calculation using CFD techniques
Ye Chuan, Ma Dongli
2013, 39(2): 196-200,219.
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Only the sum of aircraft pitching moment angle of attack(AOA) rate derivative and pitch rate derivative could be obtained by simulating the forced pitch oscillation using the unsteady flow numerical calculation method. But the dynamic stability analysis needs separate dynamic derivatives. To solve this problem, the sliding mesh was applied to simulate the forced pitch oscillation, and the sum of pitching moment AOA rate derivative and pitch rate derivative was obtained. Then the rotating reference frame was used to gain the pitching moment pitch rate derivative by simulating the steady climb movement. The rotating reference frame was also employed to acquire the rolling moment roll rate derivative by simulating the steady roll movement. The dynamic derivatives of a missile with cruciform tails and a seaplane were calculated. The results were consistent with experimental data, reference data and results acquired using other methods, indicating that this method could be used to calculate the dynamic derivatives of aircrafts with complicated configurations.
Attitude stabilization and power compensation control for spacecraft with VSCMGs
Tian Lin, Xu Shijie
2013, 39(2): 201-205.
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Based on dynamics model of variable speed control moment gyroscopes (VSCMGs), the mixed control equation plus subsystems- decoupling constraint equation were established. The attitude and energy mixed control steering law was developed synchronously via matrix projection method. Influence of flywheel rotor's moment of inertia error on attitude control subsystem was analyzed by using Lyapunov method. A power control compensator was proposed according to the error relationship between rotor's axial moment of inertia and power output. Torque and power solutions in the mixed steering law possess same forms, while the constraint equation makes the attitude and energy control subsystems decoupled. Performance analysis of closed-loop system considering actuator's characteristic becomes more convenient. Attitude control subsystem with the rotor's inertia error can maintain its stability due to the system's output dissipative property, while output error of energy control subsystem is proportional to the rotor's inertia error. The power output after being compensated can satisfy the control requirement.
Dew point measurement based on the sensitive circuit
Nie Jing, Meng Xiaofeng, Wang Shuo, Zheng Rui
2013, 39(2): 206-209.
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According to the problem of atmospheric humidity measurements, the dew point measurement method was proposed based on the sensitive circuit. The quartz crystal as a humidity sensor, when water condensation produced by the Peltier cooling appears on the quartz crystal, the test circuit will stop the vibration. Use this characteristics of colpitts oscillator distinguish the dew point and can get the dew point temperature. The measurement results with the proposed method were compared with the actual data. Though some measurement error was yielded, it is proved that the proposed method is useful for measuring the dew point of moist air and it has some advantages such as simple, high sensitivity, good reliability and low cost.
Matching design for payload and range of civil aircraft family
Meng Wengong, Ma Dongli, Cui Fei
2013, 39(2): 210-214.
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There has been a pattern transform from single model to family with multiple models for the civil aircraft-developing concept. According to the strategies of modularization and generality,the aircraft family design method was developed. The design principle of the main parameters and the economic description method for the aircraft family were presented. Then the matching design model for payload and range of the aircraft family was established. The impact of the matching relationship of the payload and the range acting on the economy of the aircraft family was analyzed, too. With application of Pareto multi-objective genetic algorithm, the matching design for payload and range of a civil aircraft family was accomplished. The parameter comparison of different design schemes was carried out,and the results are satisfactory.
Stability region for closed-loop pilot-vehicle system with actuator rate saturation
Cao Qimeng, Li Yinghui, Xu Haojun
2013, 39(2): 215-219.
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To solve advanced warplanes flight safety problem caused by category Ⅱ pilot induced oscillations(PIOs), the stability region of closed-loop pilot-vehicle system with actuator rate saturation was studied. The nonlinear model of closed-loop pilot-vehicle system was built. The augmented state variables and saturation degree function were introduced to address the rate saturation element. The ellipsoidal invariant sets were applied to estimate the stability region of closed-loop pilot-vehicle system. The stability region estimating algorithm was obtained. The stability region conservatism was investigated by time domain simulation and the effects of pilot control gain and rate saturation value on the stability region were researched. The results show that the stability region method has specific physical concept and illustrative results, and can be applied to evaluate the stability of closed-loop pilot-vehicle system. The results can provide a theoretical guidance for designing flight control systems of advanced warplanes.
Application of the trihedral corner reflector in RCS calibration test
Ou Naiming, Bai Ming, Liang Bin, Miao Jungang
2013, 39(2): 220-224.
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The scattering properties of the trihedral corner reflector was analyzed, and its application plans in monostatic radar cross section(RCS) calibration test and transmit-receive separate monostatic RCS calibration test were proposed based on the analysis. The main lobe of the backscattering pattern of the trihedral corner reflector is broad and flat, and it has strong aspect stability, so it is suitable to the monostatic calibration test for the targets with large RCS. But in the transmit-receive separate monostatic RCS calibration test system, due to the small bi-static angle between the transmitter feed and the receiver feed, the main lobe of the backscattering pattern of the trihedral corner reflector sharply drops and presents strong ripple, so it could not be used to calibration test in this situation. Nevertheless, one side lobe of the backscattering pattern almost no changes when the small bi-static angle is existent, and it also has strong aspect stability, so it could be used as the calibration reference point in the transmit-receive separate monostatic RCS calibration test.
Rapid large frequency offset estimation for DTMB system
Zhang Shuai, Zhang Xiaolin
2013, 39(2): 225-229.
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A frequency synchronization algorithm for digital terreslrial television multimedia broadcasting (DTMB) system with a large frequency offset was developed. The estimated frequency offset was obtained by differential correlation between received pseudo noise (PN) sequence and local PN sequence based on the m sequence cyclic shift-and-add property. Best linear unbiased estimator was used to enlarge the estimation range and maintain the estimation accuracy. This scheme could finish carrier frequency acquisition even with large frequency offset in a short time, and provide the necessary conditions for frequency offset tracking. Simulation results under AWGN and multipath channels show that the proposed scheme enlarges the frequency estimation range by H times with the same accuracy compared with the traditional differential correlation algorithm used for frequency synchronization in DTMB system.
Prediction of lunar rover's moon tractive performance based on similitude theory
Li Meng, Gao Feng, Sun Peng, Cui Ying
2013, 39(2): 230-234.
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Similitude theory was introduced to study the wheel-soil interaction system of lunar rover, the terramechanical similitude model of the system was created. To predict a lunar rover's tractive performance under moon gravity, a model experimental method was presented based on lunar soil's lower cohesion. In this method, both the wheel shape and wheel size are invariable, the lunar soil simulant can be used as the model experimental soil. The indoor soil-bin test and particle flow simulation were combined to verify the effectiveness of this method, the verification result shows good accordance with the derived consequence of theoretical analysis, which indicates that the method has good feasibility and validity, thereby it can be used to predict a rover's tractive performance on lunar surface.
Effect on the characteristic of silicon drift detector by electron exposure
Zhang Binquan, Wei Fei, Leng Shuang, Wang Shijin
2013, 39(2): 235-238.
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Detection characteristics of the silicon drift detector (SDD), which is used in the new generation of solar x-ray detector onboard FY-2 satellite, might change due to the exposure of long-term high-energy electron radiation. To test the effect on its energy resolution, efficiency, signal amplitude and other characteristics by electron exposure, an SDD was irradiated using electron radionuclide sources, which is to simulate the space electron radiation. Experiment result shows that both surface damage and bulk damage occur after long-term electron irradiation on the SDD. The SDD's leakage currents increase; its signal amplitude decrease and energy resolution is also affected by the electron irradiation. No changes in detection efficiency are found.
Conceptual design optimization of stratosphere airship based on improved CO-RS
Liang Haoquan, Zhu Ming, Jiang Guangtai, Wu Zhe
2013, 39(2): 239-243.
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An improved collaborative optimization based on response surface(CO-RS) methodology was developed to be well applied to the engineering design. The response surface was constructed independent on gradient by augmented Lagrange and trust region optimization methods. System mission requirements and disciplinary coupling relations of stratosphere airship were analyzed in the framework of improved CO-RS.multidisciplinary design optimization(MDO) model coupled with dynamics and propulsion subsystem, structure subsystem, and energy subsystem analysis models was established with total mass as the objective for stratosphere airship conceptual design. Using the iSIGHT software to construct the solving architecture, the MDO model and analysis models were simulated and calculated with the improved CO-RS methodology. The results prove the rationality of the MDO model and the effectiveness of the improved CO-RS methodology in stratosphere airship conceptual design optimization.
Anti-TBM task iteration convergence characteristics with resource constraint
Dong Tao, Liu Fuxian, Li Xiang, Zhang Hui
2013, 39(2): 244-247.
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In order to improve anti tactical ballistic missile (ATBM) task implement efficiency,ATBM task about total amount model and iteration convergence rule were studied.Interaction level between tasks was described based on task transform matrix.Task amount completion proportion parameter was introduced into cooperative ATBM characteristics. Task total amount model was established and revealed iteration convergence rule was revealed. After investigating research result, the main factors which influenced iteration convergence were found. In view of resource constraint and time optimization, task key degree and planned tasks priority were determined. Iteration convergence speed of anti-TBM task was controlled by optimal resource allocation.Combined with an application case, it verified that task total amount model and iteration convergence rule were reasonable and practical. The result provides theory basis and valuable methods to calculate and optimize ATBM task.
Parametric analysis on hybrid plain woven fabric laminates repaired by full depth scarfing
Liu Sui, Guan Zhidong, Guo Xia, Xi Guofen
2013, 39(2): 248-253,263.
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Based on the software of ABAQUS,a finite element model was developed in the study of simulating the ultimate tensile strength and failure mode of repaired specimens. To certify the validation of the model, an experimental study was carried out on intact and repaired laminates. The calculated results are coordinate with the tested results very well. Parametric study was conducted on the model to investigate the influence of ultimate tensile strength on changes of scarf ratio, toughness of adhesive, thickness of adhesive, dimension of damage and extra repair plies. The results of the investigation provide insight into the repair design method on hybrid plain woven fabric laminates with penetrate damage.
Dynamic image processing method of droplets impingement characteristics measurement
Liu Danyang, Han Yahui, Wang Chao, Yang Chunxin
2013, 39(2): 254-258.
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Test cylinders were made up by gypsum. Dying process videos at different locations on test cylinders were collected. A complete test was divided into three ages: sub-dyed, balanced and over-dyed according to the color increase on stagnation point. The relationship between RGB colourity and the local water droplet collecting parameter was build. Results show that the normalized color distribution agrees well with the opposition between local water droplet collecting parameter and stagnation point water collecting parameter. Color increase characteristic among different locations on cylinder are similarity. The rate of time reduction at different location can be deduced to the definition of β/βm in Euler-simulation method, error between test and simulation result was less than 10%.
Experiment investigation on the effect of heat treatment on metal rubber mechanical properties
Liu Baolong, Ma Yanhong, Zhang Dayi, Hong Jie
2013, 39(2): 259-263.
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The relief annealing was applied to the metal rubber forming process to clear the residual stress in wires and obtain stable mechanical properties. The quasi-static experiments were conducted to study the effect of relief annealing on the metal rubber in both free and precompression conditions. The results show that the stiffness of the metal rubber samples increase by more than 1.5 times after relief annealing while the loss factor change little. For the sample subjected to heat treatment, its stiffness keeps stable in free condition as the operating temperature rising, but increases in the precompression state resulting from the internal thermal expansion stress. The loss factor in both conditions keeps stable with a change less than 10% in the same temperature history. For the samples without heat treatment, the geometric and mechanical properties deviate from the initial values as the temperature rising. So it is concluded that the relief annealing is necessary for the metal rubber to obtain stable geometric and mechanical characteristics in high operating temperature.
CFD numerical simulation of cryogenic propellant vaporization in tank
Chen Liang, Liang Guozhu, Deng Xinyu, Hu Wei
2013, 39(2): 264-268.
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Simulation on heat and mass transfer in propellant tank was performed to investigate influence of cryogenic propellant vaporization on tank pressure and propellant temperature. The simulation was concerned with heat transfer between propellant tank and external environment, propellant free convection, thermal exchange between propellant and inner tank wall surface, and cryogenic propellant phase transition. A propellant phase transformation model was built on the basis of thermodynamic equilibrium. Physical process of 450s in propellant tank during ground parking under atmospheric pressure was simulated using computational fluid dynamic(CFD) method. Simulation results reveal that the propellant temperature distribution, flow state and phase transition will tend to stable as propellant tank wall heat transfer stabilizes. The evaporation of propellant per unit time was obtained through simulation. And the main factors affecting the propellant phase transition are heat leak from tank walls and the propellant's own convection motion.
Support-vector-based iteratively adjusted centroid classifier for text categorization
Wang Deqing, Zhang Hui
2013, 39(2): 269-274.
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To address the lackness of centroid-based classifier (CC) that is prone to generate inductive bias or model misfit, a support-vector-based iteratively-adjusted centroid classifier (IACC_SV) was proposed, which employs support vectors found by some routines, e.g., linear support vector machines (SVMs) to construct centroid vectors for CC, and then iteratively adjusts the initial centroid vectors according to the misclassified training samples. Compared with traditional classification algorithms, IACC_SV achieves better performance in terms of macro-F1 and micro-F1, and the extensive experiments on 8 real-world text corpora demonstrate the effectiveness of the proposed algorithm, especially on text corpora with highly imbalanced classes.
Adaptive dynamic surface control for aircraft flight path angle
Guo Yi, Liu Jinkun
2013, 39(2): 275-279.
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For the feature that aircraft longitudinal dynamics include parametric uncertainties and external disturbances, an adaptive dynamic surface controller was proposed for flight path angle. Dynamic surface control method eliminated the problem of "explosion of complexity" existing in traditional backstepping approach with the introduction of low pass filters. Adaptive laws were designed to estimate unknown parameters of the model and nonlinear damping items were used to overcome the external disturbances. From Lyapunov stability analysis, it was shown that the control strategy guaranteed the semi-global stability of the closed-loop system, and made the tracking error arbitrarily small by adjusting the controller parameters. Simulation results indicate that the proposed scheme can make flight path angle track the desired trajectory with simplifying the control design procedure. The control system has strong adaptive capability and is robust to external disturbances.
Electrochemical preparation of Ag nanostructures and their surface enhanced Raman scattering effects
Sun Jie, Xu Di, Diao Peng, Yin Penggang
2013, 39(2): 280-284.
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Ag nanostructures were successfully prepared on indium tin oxide(ITO) surfaces through electrochemical deposition. These nanostructures possessed uniform morphology. The concentration of AgNO3, the nucleation potential, the growth potential and the addition of sodium citrate greatly affected the morphology and density of the as-prepared Ag nanostructures. Only when these parameters were reasonably set could Ag nanostructures with well-defined morphology and considerable density be obtained. Investigation on surface enhanced Raman scattering(SERS) activities of the as-prepared Ag nanostructures was also carried out under 633 nm excitation, using p-aminothiophenol (p-ATP) as the probe molecule. The results show that they can serve as potential SERS substrates.

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