International Journal of Aerospace Engineering
http://www.i-scholar.in/index.php/ij-ae
<p>International Journal of Aerospace Engineering is a peer-reviewed, open access journal that aims to serve the international aerospace engineering community through dissemination of scientific knowledge on practical engineering and design methodologies pertaining to aircraft and space vehicles.</p>en-USijae@hindawi.com (Dr. Noor Afzal)ijae@hindawi.com (Dr. Noor Afzal)Thu, 21 Apr 2016 00:00:00 +0000OJS 2.4.2.0http://blogs.law.harvard.edu/tech/rss60A Simplified Mobile Ad Hoc Network Structure for Helicopter Communication
http://www.i-scholar.in/index.php/ij-ae/article/view/96956
There are a number of volunteer and statutory organizations who are capable of conducting an emergency response using helicopters. Rescue operations require a rapidly deployable high bandwidth network to coordinate necessary relief efforts between rescue teams on the ground and helicopters. Due to massive destruction and loss of services, ordinary communication infrastructures may collapse in these situations. Consequently, information exchange becomes one of themajor challenges in these circumstances. Helicopters can be also employed for providing many services in rugged environments, military applications, and aerial photography. Ad hoc network can be used to provide alternative communication link between a set of helicopters, particularly in case of significant amount of data required to be shared. This paper addresses the ability of using ad hoc networks to support the communication between a set of helicopters. A simplified network structure model is presented and extensively discussed. Furthermore, a streamlined routing algorithm is proposed. Comprehensive simulations are conducted to evaluate the proposed routing algorithm.Abdeldime Mohamed Salih Abdelgader, Lenan Wu, Mohammed Mohsen Mohammed Nasrhttp://www.i-scholar.in/index.php/ij-ae/article/view/96956Triangle Interception Scenario:A Finite-Time Guidance Approach
http://www.i-scholar.in/index.php/ij-ae/article/view/96962
Considering an aircraft threatened by an interceptor, one of the effective penetration strategies is to release a Defender from the aircraft to confront the interceptor. In this case, the aircraft, the Defender, and the interceptor constitute the three-body guidance relationship, and the cooperation of the aircraft and its Defender to achieve the best tactical effects turns into a concerned problem. This paper studies the triangle interception guidance problem via the finite-time theory. The paper presents linear system Input- Output Finite-Time Stabilization (IO-FTS) method.The sufficient conditions of the linear system, being IO-FTS, under Finite-Time Boundedness (FTB) constraint are proposed, by which the state feedback controllers design method is obtained, via LinearMatrix Inequalities (LMIs).The triangle interception guidance problems are studied in three different cases, where the proposed methods are applied to the guidance design.The simulation results illustrate the effectiveness of the proposed methods.Yang Guo, Xiaoxiang Hu, Fenghua He, Hongjie Cheng, Qinhe Gaohttp://www.i-scholar.in/index.php/ij-ae/article/view/96962Receptivity of Boundary Layer over a Blunt Wedge due to Freestream Pulse Disturbances at Mach 6
http://www.i-scholar.in/index.php/ij-ae/article/view/96971
Direct numerical simulation (DNS) of a hypersonic compressible flow over a blunt wedge with fast acoustic disturbances in freestreamis performed.Thereceptivity characteristics of boundary layer to freestreampulse acoustic disturbances are numerically investigated at Mach 6, and the frequency effects of freestream pulse wave on boundary layer receptivity are discussed. Results show that there are several main disturbance mode clusters in boundary layer under acoustic pulse wave, and the number of main disturbance clusters decreases along the streamwise. As disturbance wave propagates from upstream to downstream direction, the component of the modes below fundamental frequency decreases, and the component of the modes above second harmonic components increases quickly in general.There are competition and disturbance energy transfer between different boundary layer modes. The nose boundary layer is dominated by the nearbymode of fundamental frequency. The number of themain disturbance mode clusters decreases as the freestream disturbance frequency increases. The frequency range with larger growth narrows along the streamwise. In general, the amplitudes of both fundamental mode and harmonics become larger with the decreasing of freestreamdisturbance frequency.High frequency freestreamdisturbance accelerates the decay of disturbance wave in downstream boundary layer.Jianqiang Shi, Xiaojun Tang, Zhenqing Wang, Mingfang Shi, Wei Zhaohttp://www.i-scholar.in/index.php/ij-ae/article/view/96971Monte Carlo Uncertainty Quantification Using Quasi-1D SRM Ballistic Model
http://www.i-scholar.in/index.php/ij-ae/article/view/96976
Compactness, reliability, readiness, and construction simplicity of solid rocket motors make them very appealing for commercial launcher missions and embarked systems. Solid propulsion grants high thrust-to-weight ratio, high volumetric specific impulse, and a Technology Readiness Level of 9. However, solid rocket systems are missing any throttling capability at run-time, since pressure-time evolution is defined at the design phase. This lack of mission flexibility makes their missions sensitive to deviations of performance from nominal behavior. For this reason, the reliability of predictions and reproducibility of performances represent a primary goal in this field. This paper presents an analysis of SRM performance uncertainties throughout the implementation of a quasi-1D numerical model of motor internal ballistics based on Shapiro's equations.The code is coupled with a Monte Carlo algorithmto evaluate statistics and propagation of some peculiar uncertainties fromdesign data to rocker performance parameters. The model has been set for the reproduction of a small-scale rocket motor, discussing a set of parametric investigations on uncertainty propagation across the ballistic model.Davide Vigano, Adriano Annovazzi, Filippo Maggihttp://www.i-scholar.in/index.php/ij-ae/article/view/96976Unmanned Aerial Vehicles for Photogrammetry:Analysis of Orthophoto Images over the Territory of Lithuania
http://www.i-scholar.in/index.php/ij-ae/article/view/96982
It has been recently observed that aircrafts tend to be replaced by light, simple structure unmanned aerial vehicles (UAV) or mini unmanned aerial vehicles (MUAV) with the purpose of updating the field of aerial photogrammetry. The built-in digital photo camera takes images of the Earth's surface. To satisfy the photogrammetric requirements of the photographic images, it is necessary to carry out the terrestrial project planning of the flight path before the flight, to select the appropriate flying height, the time for acquiring images, the speed of the UAV, and other parameters. The paper presents the results of project calculations concerning the UAV flights and the analysis of the terrestrial images acquired during the field-testing flights. The experience carried out so far in the Lithuanian landscape is shown. The taken images have been processed by PhotoMod photogrammetric system.The paper presents the results of calculation of the project values of the UAV flights taking the images by digital camera Canon S100 and the analysis of the possibilities of the UAV orthophoto images' mode.J. Suziedelyte Visockiene, R. Puziene, A. Stanionis, E. Tumelienehttp://www.i-scholar.in/index.php/ij-ae/article/view/96982A Fault-Tolerant Multiple Sensor Fusion Approach Applied to UAV Attitude Estimation
http://www.i-scholar.in/index.php/ij-ae/article/view/96989
A novel sensor fusion design framework is presented with the objective of improving the overall multisensor measurement system performance and achieving graceful degradation following individual sensor failures. The Unscented Information Filter (UIF) is used to provide a useful tool for combining information from multiple sources. A two-step off-line and on-line calibration procedure refines sensor error models and improves the measurement performance. A Fault Detection and Identification (FDI) scheme crosschecks sensor measurements and simultaneously monitors sensor biases. Low-quality or faulty sensor readings are then rejected from the final sensor fusion process. The attitude estimation problem is used as a case study for the multiple sensor fusion algorithm design, with information provided by a set of low-cost rate gyroscopes, accelerometers, magnetometers, and a single-frequency GPS receiver's position and velocity solution. Flight data collected with an Unmanned Aerial Vehicle (UAV) research test bed verifies the sensor fusion, adaptation, and fault-tolerance capabilities of the designed sensor fusion algorithm.Yu Gu, Jason N. Gross, Matthew B. Rhudy, Kyle Lassakhttp://www.i-scholar.in/index.php/ij-ae/article/view/96989Integrated Power and Attitude Control Design of Satellites Based on a Fuzzy Adaptive Disturbance Observer Using Variable-Speed Control Moment Gyros
http://www.i-scholar.in/index.php/ij-ae/article/view/96991
To satisfy the requirements for small satellites that seek agile slewing with peak power, this paper investigates integrated power and attitude control using variable-speed control moment gyros (VSCMGs) that consider the mass and inertia of gimbals and wheels. Thepaper also details the process for developing the controller by considering various environments in which the controller may be implemented. A fuzzy adaptive disturbance observer (FADO) is proposed to estimate and compensate for the effects of equivalent disturbances. The algorithms can simultaneously track attitude and power. The simulation results illustrate the effectiveness of the control approach, which exhibits an improvement of 80 percent compared with alternate approaches that do not employ a FADO.Zhongyi Chu, Jing Cuihttp://www.i-scholar.in/index.php/ij-ae/article/view/96991Study on Impedance Characteristics of Aircraft Cables
http://www.i-scholar.in/index.php/ij-ae/article/view/96998
Voltage decrease and power loss in distribution lines of aircraft electric power system are harmful to the normal operation of electrical equipment and may even threaten the safety of aircraft. This study investigates how the gap distance (the distance between aircraft cables and aircraft skin) and voltage frequency (variable frequency power supply will be adopted for next generation aircraft) will affect the impedance of aircraft cables. To be more precise, the forming mechanism of cable resistance and inductance is illustrated in detail and their changing trends with frequency and gap distance are analyzed with the help of electromagnetic theoretical analysis. An aircraft cable simulation model is built with Maxwell 2D and the simulation results are consistent with the conclusions drawn from the theoretical analysis. The changing trends of the four core parameters of interest are analyzed: resistance, inductance, reactance, and impedance. The research results can be used as reference for the applications in Variable Speed Variable Frequency (VSVF) aircraft electric power system.Weilin Li, Wenjie Liu, Xiaobin Zhang, Zhaohui Gao, Meng Xie, Hongxia Wanghttp://www.i-scholar.in/index.php/ij-ae/article/view/96998Adaptive Flutter Suppression for a Fighter Wing via Recurrent Neural Networks over a Wide Transonic Range
http://www.i-scholar.in/index.php/ij-ae/article/view/97001
The paper presents a digital adaptive controller of recurrent neural networks for the active flutter suppression of a wing structure over a wide transonic range. The basic idea behind the controller is as follows. At first, the parameters of recurrent neural networks, such as the number of neurons and the learning rate, are initially determined so as to suppress the flutter under a specific flight condition in the transonic regime. Then, the controller automatically adjusts itself for a newflight condition by updating the synaptic weights of networks online via the real-time recurrent learning algorithm. Hence, the controller is able to suppress the aeroelastic instability of the wing structure over a range of flight conditions in the transonic regime. To demonstrate the effectiveness and robustness of the controller, the aeroservoelastic model of a typical fighter wing with a tip missile was established and a singleinput/ single-output controller was synthesized. Numerical simulations of the open/closed-loop aeroservoelastic simulations were made to demonstrate the efficacy of the adaptive controller with respect to the change of flight parameters in the transonic regime.Haojie Liu, Yonghui Zhao, Haiyan Huhttp://www.i-scholar.in/index.php/ij-ae/article/view/97001Evaluation of the Mechanical Properties of Microcapsule-Based Self-Healing Composites
http://www.i-scholar.in/index.php/ij-ae/article/view/97024
Self-healing materials are beginning to be considered for applications in the field of structuralmaterials. For this reason, in addition to self-healing efficiency, also mechanical properties such as tensile and compressive properties are beginning to become more and more important for this kind of materials. In this paper, three different systems based on epoxy-resins/ethylidene-norbornene (ENB)/Hoveyda-Grubbs 1st-generation (HG1) catalyst are investigated in terms of mechanical properties and healing efficiency. The experimental results show that the mechanical properties of the self-healing systems are mainly determined by the chemical nature of the epoxy matrix. In particular, the replacement of a conventional flexibilizer (Heloxy 71) with a reactive diluent (1,4- butanediol diglycidyl ether) allows obtaining self-healing materials with better mechanical properties and higher thermal stability. An increase in the curing temperature causes an increase in the elastic modulus and a slight reduction of the healing efficiency. These results can constitute the basis to design systems with high regenerative ability and appropriate mechanical performance.Liberata Guadagno, Marialuigia Raimondo, Umberto Vietri, Carlo Naddeo, Anja Stojanovic, Andrea Sorrentino, Wolfgang H. Binderhttp://www.i-scholar.in/index.php/ij-ae/article/view/97024Trajectory Optimization for Velocity Jumps Reduction Considering the Unexpectedness Characteristics of Space Manipulator Joint-Locked Failure
http://www.i-scholar.in/index.php/ij-ae/article/view/97028
Aiming at reducing joint velocity jumps caused by an unexpected joint-locked failure during space manipulator on-orbit operations without shutting downmanipulator, trajectory optimization strategy considering the unexpectedness characteristics of joint-locked failure is proposed in the paper, which can achieve velocity jumps reduction in both operation space and joint space simultaneously. In the strategy, velocity in operation space concerning task completion directly is treated as equality constraints, and velocity in joint space concerning motion performance is treated as objective function. Global compensation vector which consists of coefficient, gradient of manipulability, and orthogonal matrix of null space is constructed to minimize the objective function. For each particular failure time, unique optimal coefficient can be obtainedwhen the objective function is minimal. As a basis, amethod for optimal coefficient function fitting is proposed based on a priori failure information (possible failure time and the corresponding optimal coefficient) to guarantee the unexpectedness characteristics of joint-locked failure. Simulations are implemented to validate the efficiency of trajectory optimization strategy in reducing velocity jumps in both joint space and operation space. And the feasibility of coefficient function is also verified in reducing velocity jump no matter when joint-locked failure occurs.Qingxuan Jia, Tong Li, Gang Chen, Hanxu Sun, Jian Zhanghttp://www.i-scholar.in/index.php/ij-ae/article/view/97028Precise Orbit Determination of BDS MEO Satellites Based on Satellite TT&C Stations
http://www.i-scholar.in/index.php/ij-ae/article/view/97036
A novel method, which is based on the triple-frequency combination and Space-Based Telemetry, Tracking, and Command (STT&C) stations, is proposed in this paper.Considering BeiDouNavigation Satellite System (BDS) Geostationary Orbit (GEO) and Inclined Geostationary Orbit (IGSO) satellites as the STT&C facilities, firstly, we presented the BDS Medium Earth Orbit (MEO) satellites' precise orbit determination scheme based on triple-frequency combination. Then, we gave the sufficient and necessary conditions about the visibility and the coverage rate calculation model of STT&C to BDS MEO satellite. And then we deduced the model of BDS MEO satellites precise orbit determination based on triple-frequency combination observations. At last, we designed the simulation calculation. The simulation results show that orbit determination of BDS MEO satellite based on STT&C station can be realized at all times. And most of the simulation period time, under the condition of the dm level orbit determination for GEO/IGSO satellites, the position accuracy of the relative orbit determination is better than 4 m, the horizontal accuracy of the relative orbit determination is within 2.5m, and the vertical accuracy of the relative orbit determination is less than 3.5 m.Kezhao Li, Zhiwei Li, Lin Chai, An-min Ding, Jin-ben Wei, Long Lihttp://www.i-scholar.in/index.php/ij-ae/article/view/97036Aero Engine Fault Diagnosis Using an Optimized Extreme Learning Machine
http://www.i-scholar.in/index.php/ij-ae/article/view/97041
A new extreme learning machine optimized by quantum-behaved particle swarm optimization (QPSO) is developed in this paper. It uses QPSO to select optimal network parameters including the number of hidden layer neurons according to both the root mean square error on validation data set and the norm of output weights. The proposed Q-ELM was applied to real-world classification applications and a gas turbine fan engine diagnostic problem and was compared with two other optimized ELM methods and original ELM, SVM, and BP method. Results show that the proposed Q-ELM is a more reliable and suitable method than conventional neural network and other ELM methods for the defect diagnosis of the gas turbine engine.Xinyi Yang, Shan Pang, Wei Shen, Xuesen Lin, Keyi Jiang, Yonghua Wanghttp://www.i-scholar.in/index.php/ij-ae/article/view/97041Modeling of Particle Trajectory and Erosion of Large Rotor Blades
http://www.i-scholar.in/index.php/ij-ae/article/view/97044
When operating in hostile environments, engines components are facing a serious problem of erosion, leading to a drastic drop in aerodynamic performance and life-cycle. This paper outlines the modeling and simulation of particle trajectory and erosion induced by sand particles.The governing equations of particle dynamics through the moving of large rotor blades are introduced and solved separately from the flow field by using our in-house particle tracking code based on the finite element method. As the locations of impacts are predicted, the erosion is assessed by semiempirical correlations in terms of impact conditions and particle and target surface characteristics. The results of these computations carried out for different concentrations of suspended dust (sand) cloud generated at takeoff conditions reveal the main areas of impacts with high rates of erosion seen over a large strip from the blade suction side, around the leading edge and the pressure side of blade. The assessment of the blade geometry deterioration reveals that the upper corner of blade suffers from an intense erosion wear.Adel Ghenaiethttp://www.i-scholar.in/index.php/ij-ae/article/view/97044Online Adaptive Error Compensation SVM-Based Sliding Mode Control of an Unmanned Aerial Vehicle
http://www.i-scholar.in/index.php/ij-ae/article/view/97048
Unmanned Aerial Vehicle (UAV) is a nonlinear dynamic system with uncertainties and noises. Therefore, an appropriate control system has an obligation to ensure the stabilization and navigation of UAV. This paper mainly discusses the control problem of quad-rotor UAV system, which is influenced by unknown parameters and noises. Besides, a sliding mode control based on online adaptive error compensation support vector machine (SVM) is proposed for stabilizing quad-rotor UAV system. Sliding mode controller is established through analyzing quad-rotor dynamicsmodel in which the unknown parameters are computed by offline SVM. During this process, the online adaptive error compensation SVM method is applied in this paper. As modeling errors and noises both exist in the process of flight, the offline SVM one-time mode cannot predict the uncertainties and noises accurately. The control law is adjusted in real-time by introducing new training sample data to online adaptive SVM in the control process, so that the stability and robustness of flight are ensured. It can be demonstrated through the simulation experiments that the UAV that joined online adaptive SVM can track the changing path faster according to its dynamic model. Consequently, the proposed method that is proved has the better control effect in the UAV system.Kaijia Xue, Congqing Wang, Zhiyu Li, Hanxin Chenhttp://www.i-scholar.in/index.php/ij-ae/article/view/97048Effects of Duct Cross Section Camber and Thickness on the Performance of Ducted Propulsion Systems for Aeronautical Applications
http://www.i-scholar.in/index.php/ij-ae/article/view/97052
The axisymmetric flow field around a ducted rotor is thoroughly analysed by means of a nonlinear and semi-analytical model which is able to deal with some crucial aspects of shrouded systems like the interaction between the rotor and the duct, and the slipstream contraction and rotation. Not disregarding the more advanced CFD based methods, the proposed procedure is characterised by a very low computational cost that makes it very appealing as analysis tool in the preliminary steps of a design procedure of hierarchical type. The work focuses on the analysis of the effects of the camber and thickness of the duct cross section onto the performance of the device. It has been found that an augmentation of both camber and thickness of the duct leads to an increase of the propulsive ideal efficiency.Rodolfo Bontempo, Marcello Mannahttp://www.i-scholar.in/index.php/ij-ae/article/view/97052Time-Varying Biased Proportional Guidance with Seekerâ€™s Field-of-View Limit
http://www.i-scholar.in/index.php/ij-ae/article/view/97053
Traditional guidance laws with range-to-go information or time-to-go estimation may not be implemented in passive homing missiles since passive seekers cannot measure relative range directly. A time-varying biased proportional guidance law, which only uses line-of-sight (LOS) rate and look angle information, is proposed to satisfy both impact angle constraint and seeker's field-ofview (FOV) limit. In the proposed guidance law, two time-varying bias terms are applied to divide the trajectory into initial phase and terminal phase. The initial bias is designed as a function of LOS rate and look angle to maintain the seeker's lock-on while the final bias eliminates the deviation between the integral value of angle control bias and the expected bias amount. A switching logic is adopted to change the biases continuously so that there is no abrupt acceleration change during the engagement. Extensive simulations considering both kinematic and realistic missile models are performed to illustrate the efficiency of the proposed method.Zhe Yang, Hui Wang, Defu Linhttp://www.i-scholar.in/index.php/ij-ae/article/view/97053