International Journal of Aerospace Engineering http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Application of Latitude Stripe Division in Satellite Constellation Coverage to Ground Tue, 29 Nov 2016 09:37:20 +0000 http://www.hindawi.com/journals/ijae/2016/4315026/ Grid point technique is a classical method in computing satellite constellation coverage to the ground regions. Aiming at improving the low computational efficiency of the conventional method, a method using latitude stripe division is proposed, which has high efficiency, and we name it latitude stripe method. After dividing the target region into several latitude stripes, the coverage status of each latitude stripe is computed by means of the spherical geometry relationship in the first orbital period. The longitude coverage intervals in the remaining orbital periods are computed by sliding the coverage status in the first orbital period. Based on this method, the instantaneous and cumulative coverage in simulation time can be calculated more efficiently. As well, the relationship between the cumulative coverage and altitude can be computed fast by this method, which could be used in the optimized design of repeating sun-synchronous orbits. The comparison between the conventional grid point method and the latitude stripe method shows that the latitude stripe method has high efficiency and accuracy. Through various case studies, the optimization in repeating sun-synchronous orbits design is successfully represented. Maocai Wang, Xin Luo, Guangming Dai, and Xiaoyu Chen Copyright © 2016 Maocai Wang et al. All rights reserved. A Novel Concept for Guidance and Control of Spacecraft Orbital Maneuvers Tue, 29 Nov 2016 08:54:49 +0000 http://www.hindawi.com/journals/ijae/2016/7695257/ The purpose of this paper is the design of guidance and control algorithms for orbital space maneuvers. A 6-dof orbital simulator, based on Clohessy-Wiltshire-Hill equations, is developed in C language, considering cold gas reaction thrusters and reaction wheels as actuation system. The computational limitations of on-board computers are also included. A combination of guidance and control algorithms for an orbital maneuver is proposed: (i) a suitably designed Zero-Effort-Miss/Zero-Effort-Velocity (ZEM/ZEV) algorithm is adopted for the guidance and (ii) a linear quadratic regulator (LQR) is used for the attitude control. The proposed approach is verified for different cases, including external environment disturbances and errors on the actuation system. Matteo Dentis, Elisa Capello, and Giorgio Guglieri Copyright © 2016 Matteo Dentis et al. All rights reserved. Preliminary Study on Aerodynamic Control of High-Angle-of-Attack Slender Body Using Blowing from Penetrating Flow Channels Sun, 27 Nov 2016 12:31:30 +0000 http://www.hindawi.com/journals/ijae/2016/1602043/ The objective of this study is to experimentally verify a new aerodynamic control concept of a high-angle-of-attack slender body. In the concept, penetrating flow channels are installed to the apex of the slender body. The blowing or suction is generated at the channel exits in response to the surface pressure distribution. First, the effects of the flow channels on the aerodynamic characteristics are experimentally investigated in a low-speed wind tunnel. The result shows the Suction-Blowing type channel is the most effective because its control effect does not reduce even in higher mainstream flow velocity. The peak value of the side force and yawing moment can be reduced by up to 64% and 49%, respectively. In addition, visualization of the surface flow pattern by the oil flow method shows that the Suction-Blowing type channel makes not only the primary separation line on the body side but also the secondary separation line on the body back become symmetric. Ayane Sato, Hiroyuki Nishida, and Satoshi Nonaka Copyright © 2016 Ayane Sato et al. All rights reserved. Three-Dimensional Integrated Guidance and Control for Near Space Interceptor Based on Robust Adaptive Backstepping Approach Thu, 24 Nov 2016 13:03:16 +0000 http://www.hindawi.com/journals/ijae/2016/6598983/ This study presents a novel integrated guidance and control method for near space interceptor, considering the coupling among different channels of the missile dynamics, which makes the most of the overall performance of guidance and control system. Initially, three-dimensional integrated guidance and control model is employed by combining the interceptor-target relative motion model with the nonlinear dynamics of the interceptor, which establishes a direct relationship between the interceptor-target relative motion and the deflections of aerodynamic fins. Subsequently, regarding the acceleration of the target as bounded uncertainty of the system, an integrated guidance and control algorithm is designed based on robust adaptive backstepping method, with the upper bound of the uncertainties unknown. Moreover, a nonlinear tracking differentiator is introduced to reduce the “compute explosion” caused by backstepping method. It is proved that tracking errors of the state and the upper bound of the uncertainties converge to the neighborhoods of the origin exponentially. Finally, simulations results show that, compared to the conventional guidance and control design, the algorithm proposed in this paper has greater advantages in miss distance, required normal overload, and flight stability, especially when attacking high-maneuvering targets. Changsheng Gao, Chunwang Jiang, Yan Zhang, and Wuxing Jing Copyright © 2016 Changsheng Gao et al. All rights reserved. A Bayesian Classifier for X-Ray Pulsars Recognition Thu, 24 Nov 2016 05:44:38 +0000 http://www.hindawi.com/journals/ijae/2016/1746925/ Recognition for X-ray pulsars is important for the problem of spacecraft’s attitude determination by X-ray Pulsar Navigation (XPNAV). By using the nonhomogeneous Poisson model of the received photons and the minimum recognition error criterion, a classifier based on the Bayesian theorem is proposed. For X-ray pulsars recognition with unknown Doppler frequency and initial phase, the features of every X-ray pulsar are extracted and the unknown parameters are estimated using the Maximum Likelihood (ML) method. Besides that, a method to recognize unknown X-ray pulsars or X-ray disturbances is proposed. Simulation results certificate the validity of the proposed Bayesian classifier. Hao Liang, Yafeng Zhan, and Chaowei Duan Copyright © 2016 Hao Liang et al. All rights reserved. Online Fault-Tolerant Onboard Aeroengine Model Tuning Structure Sun, 20 Nov 2016 07:36:47 +0000 http://www.hindawi.com/journals/ijae/2016/7904657/ Online onboard aeroengine models (OBEMs) have been widely used in health management, fault diagnostics, and fault-tolerant control. A mismatch between the OBEM and the actual engine may be caused by a variety of factors such as health degradation or sensor fault and may influence the effectiveness of the systems mentioned above. However, mismatch caused by unpredictable sensor fault is hardly distinguished from that caused by health degradation through the tuning process. A fault-tolerant OBEM tuning structure is provided to perform the online tuning function when health degradation and sensor fault coexist. This system includes three parts that include improved fault diagnostics and isolation (IFDI), a fault-tolerant OBEM tuning system (FTOTS), and a channel switching module. IFDI is used to distinguish the cause of mismatch and provide fault information, a FTOTS is used to complete an online tuning process based on information obtained from the IFDI, and the channel switching module is used to switch the working process from the IFDI to the FTOTS. Several simulation results show that this system is able to distinguish the causes of mismatch and complete online tuning in the case of sensor faults. Shuiting Ding, Ye Yuan, Naiyu Xue, and Xiaofeng Liu Copyright © 2016 Shuiting Ding et al. All rights reserved. Detecting Silent Data Corruptions in Aerospace-Based Computing Using Program Invariants Tue, 15 Nov 2016 12:06:34 +0000 http://www.hindawi.com/journals/ijae/2016/8213638/ Soft error caused by single event upset has been a severe challenge to aerospace-based computing. Silent data corruption (SDC) is one of the results incurred by soft error. SDC occurs when a program generates erroneous output with no indications. SDC is the most insidious type of results and very difficult to detect. To address this problem, we design and implement an invariant-based system called Radish. Invariants describe certain properties of a program; for example, the value of a variable equals a constant. Radish first extracts invariants at key program points and converts invariants into assertions. It then hardens the program by inserting the assertions into the source code. When a soft error occurs, assertions will be found to be false at run time and warn the users of soft error. To increase the coverage of SDC, we further propose an extension of Radish, named Radish_D, which applies software-based instruction duplication mechanism to protect the uncovered code sections. Experiments using architectural fault injections show that Radish achieves high SDC coverage with very low overhead. Furthermore, Radish_D provides higher SDC coverage than that of either Radish or pure instruction duplication. Junchi Ma, Dengyun Yu, Yun Wang, Zhenbo Cai, Qingxiang Zhang, and Cheng Hu Copyright © 2016 Junchi Ma et al. All rights reserved. Aerodynamic Optimization Based on Continuous Adjoint Method for a Flexible Wing Tue, 15 Nov 2016 09:29:13 +0000 http://www.hindawi.com/journals/ijae/2016/4706925/ Aerodynamic optimization based on continuous adjoint method for a flexible wing is developed using FORTRAN 90 in the present work. Aerostructural analysis is performed on the basis of high-fidelity models with Euler equations on the aerodynamic side and a linear quadrilateral shell element model on the structure side. This shell element can deal with both thin and thick shell problems with intersections, so this shell element is suitable for the wing structural model which consists of two spars, 20 ribs, and skin. The continuous adjoint formulations based on Euler equations and unstructured mesh are derived and used in the work. Sequential quadratic programming method is adopted to search for the optimal solution using the gradients from continuous adjoint method. The flow charts of rigid and flexible optimization are presented and compared. The objective is to minimize drag coefficient meanwhile maintaining lift coefficient for a rigid and flexible wing. A comparison between the results from aerostructural analysis of rigid optimization and flexible optimization is shown here to demonstrate that it is necessary to include the effect of aeroelasticity in the optimization design of a wing. Zhaoke Xu and Jian Xia Copyright © 2016 Zhaoke Xu and Jian Xia. All rights reserved. Experimental Study of Torque Using a Small Scoop on the Lunar Surface Mon, 14 Nov 2016 14:07:27 +0000 http://www.hindawi.com/journals/ijae/2016/8035456/ Chinese missions to the moon are planned to sample the regolith and return it to the earth. Microscale excavators may be good candidates for these missions, as they would significantly reduce the launch mass. Thus, it is necessary to research the interaction between the scoop and the regolith being sampled. We present the development of a simple apparatus to measure excavation torque. All tests were conducted using TYII-2 regolith simulant with gravels. The test results show that, under loose regolith conditions, the penetrating angle and the bulk density had a great influence on the excavation torque, while the rotating speed had little effect. However, when the bulk density was compact, the rotating speed did influence the excavation torque. The excavation torque increased sharply when the scoop encountered the gravels; actually, some of the parameters will influence the value of the torque such as the diameter, quantity, and position and inbuilt depth of the gravels. When the excavation torque sharply increases, the operation should be immediately stopped and checked. Long Xue, Baichao Chen, Zhenjia Zhao, Zhaolong Dang, and Meng Zou Copyright © 2016 Long Xue et al. All rights reserved. A GRASP for Next Generation Sapphire Image Acquisition Scheduling Mon, 14 Nov 2016 12:20:37 +0000 http://www.hindawi.com/journals/ijae/2016/3518537/ This paper investigates an image acquisition scheduling problem for a Canadian surveillance-of-space satellite named Sapphire that takes images of deep space Earth-orbiting objects. For a set of resident space objects (RSOs) that needs to be imaged within the time horizon of one day, the Sapphire image acquisition scheduling (SIAS) problem is to find a schedule that maximizes the “Figure of Merit” of all the scheduled RSO images. To address the problem, we propose an effective GRASP heuristic that alternates between a randomized greedy constructive procedure and a local search procedure. Experimental comparisons with the currently used greedy algorithm are presented to demonstrate the merit of the proposed algorithm in handling the SIAS problem. Yang Wang, Snezana Mitrovic Minic, Robert Leitch, and Abraham P. Punnen Copyright © 2016 Yang Wang et al. All rights reserved. Simulation and Analysis of Spectral Response Function and Bandwidth of Spectrometer Sun, 13 Nov 2016 06:41:24 +0000 http://www.hindawi.com/journals/ijae/2016/2759121/ A simulation method for acquiring spectrometer’s Spectral Response Function (SRF) based on Huygens Point Spread Function (PSF) is suggested. Taking into account the effects of optical aberrations and diffraction, the method can obtain the fine SRF curve and corresponding spectral bandwidth at any nominal wavelength as early as in the design phase. A prism monochromator is proposed for illustrating the simulation procedure. For comparison, a geometrical ray-tracing method is also provided, with bandwidth deviations varying from 5% at 250 nm to 25% at 2400 nm. Further comparison with reported experiments shows that the areas of the SRF profiles agree to about 1%. However, the weak scattered background light on the level of 10−4 to 10−5 observed by experiment could not be covered by this simulation. This simulation method is a useful tool for forecasting the performance of an underdesigned spectrometer. Zhenyu Gao, Ruidong Jia, Hao Zhang, Zhiwei Xia, and Wei Fang Copyright © 2016 Zhenyu Gao et al. All rights reserved. Flutter Characteristic Study of Composite Sandwich Panel with Functionally Graded Foam Core Thu, 10 Nov 2016 13:13:19 +0000 http://www.hindawi.com/journals/ijae/2016/7971435/ This paper attempts to investigate the flutter characteristic of sandwich panel composed of laminated facesheets and a functionally graded foam core. The macroscopic properties of the foam core change continuously along this direction parallel to the facesheet lamina. The model used in the study is a simple sandwich panel-wing clamped at the root, with three simple types of grading strategies for FGM core: linear grading strategy in the chord-wise direction, linear grading strategy in the span-wise direction, and bilinear grading of properties of foam core across the panel. The results show that use of FGM core has the potential to increase the flutter speed of the sandwich panel. Finally, a minimum weight design of composite sandwich panel with lamination parameters of facesheet and density distribution of foam core as design variables is conducted using particle swarm optimization (PSO). Peng Jin and Xiaoping Zhong Copyright © 2016 Peng Jin and Xiaoping Zhong. All rights reserved. A Moving Frame Trajectory Tracking Method of a Flying-Wing UAV Using the Differential Geometry Wed, 09 Nov 2016 11:11:17 +0000 http://www.hindawi.com/journals/ijae/2016/3406256/ The problem of UAV trajectory tracking is a difficult issue for scholars and engineers, especially when the target curve is a complex curve in the three-dimensional space. In this paper, the coordinate frames during the tracking process are transformed to improve the tracking result. Firstly, the basic concepts of the moving frame are given. Secondly the transfer principles of various moving frames are formulated and the Bishop frame is selected as a final choice for its flexibility. Thirdly, the detailed dynamic equations of the moving frame tracking method are formulated. In simulation, a moving frame of an elliptic cylinder helix is formulated precisely. Then, the devised tracking method on the basis of the dynamic equations is tested in a complete flight control system with 6 DOF nonlinear equations of the UAV. The simulation result shows a satisfactory trajectory tracking performance so that the effectiveness and efficiency of the devised tracking method is proved. Yi Zhu, Xin Chen, and Chuntao Li Copyright © 2016 Yi Zhu et al. All rights reserved. Erratum to “Aeroelastic Analysis of Wings in the Transonic Regime: Planform’s Influence on the Dynamic Instability” Thu, 03 Nov 2016 13:15:27 +0000 http://www.hindawi.com/journals/ijae/2016/7403123/ Mario Rosario Chiarelli and Salvatore Bonomo Copyright © 2016 Mario Rosario Chiarelli and Salvatore Bonomo. All rights reserved. Research on the Effectiveness of Different Estimation Algorithm on the Autonomous Orbit Determination of Lagrangian Navigation Constellation Tue, 25 Oct 2016 13:49:57 +0000 http://www.hindawi.com/journals/ijae/2016/8392148/ The accuracy of autonomous orbit determination of Lagrangian navigation constellation will affect the navigation accuracy for the deep space probes. Because of the special dynamical characteristics of Lagrangian navigation satellite, the error caused by different estimation algorithm will cause totally different autonomous orbit determination accuracy. We apply the extended Kalman filter and the fading–memory filter to determinate the orbits of Lagrangian navigation satellites. The autonomous orbit determination errors are compared. The accuracy of autonomous orbit determination using fading-memory filter can improve 50% compared to the autonomous orbit determination accuracy using extended Kalman filter. We proposed an integrated Kalman fading filter to smooth the process of autonomous orbit determination and improve the accuracy of autonomous orbit determination. The square root extended Kalman filter is introduced to deal with the case of inaccurate initial error variance matrix. The simulations proved that the estimation method can affect the accuracy of autonomous orbit determination greatly. Youtao Gao, Junkang Chen, Bo Xu, and Jianhua Zhou Copyright © 2016 Youtao Gao et al. All rights reserved. Design and Test of Dual Actuator Nose Wheel Steering System for Large Civil Aircraft Wed, 19 Oct 2016 13:34:33 +0000 http://www.hindawi.com/journals/ijae/2016/1626015/ In order to improve aircraft ground handling characteristics and airport working efficiency, large handling angle and torque are requested for the nose wheel steering system of large civil aircraft. A following swivel selector valve is firstly designed to meet the demand for the hydraulic pressure commutating as soon as the dual actuator nose wheel steering mechanism passes through its dead center position. Considering the multiple objective functions of nose wheel steering mechanisms, those core design parameters are multiobjective optimized. A nose wheel steering electrohydraulic servo system with handling and antishimmy functions is designed for the steering mechanism. Then the prototypes of the steering mechanism and electrohydraulic servo system are researched to validate the design. Using the swing actuator to provide the load torque and ground excitation, the steering test bench is prepared to test the system working. The steering test and the antishimmy test are conducted to verify the functions of the system. The test results, such as steer angle, steer torque hydraulic pressure, and antishimmy torque, are analyzed in detail and compared with the theoretical results. The results show that the property of the prototype achieves the design objectives, such as work mode, steer angle, and steer torque. Ming Zhang, Rongmin Jiang, and Hong Nie Copyright © 2016 Ming Zhang et al. All rights reserved. Approximate Analytical Methodology for the Restricted Three-Body and Four-Body Models Based on Polynomial Series Wed, 19 Oct 2016 11:11:46 +0000 http://www.hindawi.com/journals/ijae/2016/9747289/ The restricted three-body problem (R3BP) and restricted four-body problem (R4BP) are modeled based on the rotating frame. The conservative autonomous system for the R3BP and nonautonomous system with period parametric resonance due to the fourth body are derived. From the vibrational point of view, the methodology of polynomial series is proposed to solve for these problems analytically. By introducing the polynomial series relations among the three directions of motion, the three-degree-of-freedom coupled equations are transferred into one degree-of-freedom containing the full dynamics of the original autonomous system for the R3BP. As for the R4BP case, the methodology of polynomial series combined with the iterative approach is proposed. During the iterative approach, the nonautonomous system can be treated as pseudoautonomous equation and the final polynomial series relations and one-degree-of-freedom system can be derived iteratively. Ying-Jing Qian, Xiao-Dong Yang, Lei-Yu Yang, and Wei Zhang Copyright © 2016 Ying-Jing Qian et al. All rights reserved. Flutter and Thermal Buckling Analysis for Composite Laminated Panel Embedded with Shape Memory Alloy Wires in Supersonic Flow Mon, 17 Oct 2016 07:34:31 +0000 http://www.hindawi.com/journals/ijae/2016/8562716/ The flutter and thermal buckling behavior of laminated composite panels embedded with shape memory alloy (SMA) wires are studied in this research. The classical plate theory and nonlinear von-Karman strain-displacement relation are employed to investigate the aeroelastic behavior of the smart laminated panel. The thermodynamic behaviors of SMA wires are simulated based on one-dimensional Brinson SMA model. The aerodynamic pressure on the panel is described by the nonlinear piston theory. Nonlinear governing partial differential equations of motion are derived for the panel via the Hamilton principle. The effects of ply angle of the composite panel, SMA layer location and orientation, SMA wires temperature, volume fraction and prestrain on the buckling, flutter boundary, and amplitude of limit cycle oscillation of the panel are analyzed in detail. Chonghui Shao, Dengqing Cao, Yuqian Xu, and Hai Zhao Copyright © 2016 Chonghui Shao et al. All rights reserved. Investigation of an Autofocusing Method for Visible Aerial Cameras Based on Image Processing Techniques Sun, 16 Oct 2016 13:59:38 +0000 http://www.hindawi.com/journals/ijae/2016/1819472/ In order to realize the autofocusing in aerial camera, an autofocusing system is established and its characteristics such as working principle and optical-mechanical structure and focus evaluation function are investigated. The reason for defocusing in aviation camera is analyzed and several autofocusing methods along with appropriate focus evaluation functions are introduced based on the image processing techniques. The proposed autofocusing system is designed and implemented using two CMOS detectors. The experiment results showed that the proposed method met the aviation camera focusing accuracy requirement, and a maximum focusing error of less than half of the focus depth is achieved. The system designed in this paper can find the optical imaging focal plane in real-time; as such, this novel design has great potential in practical engineering, especially aerospace applications. Zhichao Chen and Tao Zhang Copyright © 2016 Zhichao Chen and Tao Zhang. All rights reserved. Reliability Analysis of the Chatter Stability during Milling Using a Neural Network Thu, 13 Oct 2016 06:25:41 +0000 http://www.hindawi.com/journals/ijae/2016/5259821/ The parameters of a system have the randomness generally in the process of milling, which influences the stability of the milling. This paper uses the neural network to get a comprehensive analysis of the influences of random factors in milling and proposes a method for reliability analysis of the regenerative chatter stability in milling. Dynamic model of milling regenerative chatter is established, and stability lobe diagram is obtained by the full-discretization method (FDM). The neural network is applied to approximate the functional relationship of the limit axial cutting depth; then the reliability is computed with the Monte Carlo simulation method (MCSM) and the moment method (MM), respectively. Finally, the results of an example are used to demonstrate the efficiency and accuracy of the proposed method. Sen Hu, Xianzhen Huang, Yimin Zhang, and Chunmei Lv Copyright © 2016 Sen Hu et al. All rights reserved. Remotely Piloted Aircraft Systems and a Wireless Sensors Network for Radiological Accidents Wed, 12 Oct 2016 12:22:29 +0000 http://www.hindawi.com/journals/ijae/2016/9437165/ In critical radiological situations, the real time information that we could get from the disaster area becomes of great importance. However, communication systems could be affected after a radiological accident. The proposed network in this research consists of distributed sensors in charge of collecting radiological data and ground vehicles that are sent to the nuclear plant at the moment of the accident to sense environmental and radiological information. Afterwards, data would be analyzed in the control center. Collected data by sensors and ground vehicles would be delivered to a control center using Remotely Piloted Aircraft Systems (RPAS) as a message carrier. We analyze the pairwise contacts, as well as visiting times, data collection, capacity of the links, size of the transmission window of the sensors, and so forth. All this calculus was made analytically and compared via network simulations. A. Reyes-Muñoz, J. Guerrero-Ibáñez, E. Pastor, M. Gasull, and C. Barrado Copyright © 2016 A. Reyes-Muñoz et al. All rights reserved. Electromagnetic-Thermal Integrated Design Optimization for Hypersonic Vehicle Short-Time Duty PM Brushless DC Motor Wed, 12 Oct 2016 09:44:39 +0000 http://www.hindawi.com/journals/ijae/2016/9725416/ High reliability is required for the permanent magnet brushless DC motor (PM-BLDCM) in an electrical pump of hypersonic vehicle. The PM-BLDCM is a short-time duty motor with high-power-density. Since thermal equilibrium is not reached for the PM-BLDCM, the temperature distribution is not uniform and there is a risk of local overheating. The winding is a main heat source and its insulation is thermally sensitive, so reducing the winding temperature rise is the key to the improvement of the reliability. In order to reduce the winding temperature rise, an electromagnetic-thermal integrated design optimization method is proposed. The method is based on electromagnetic analysis and thermal transient analysis. The requirements and constraints of electromagnetic and thermal design are considered in this method. The split ratio and the maximum flux density in stator lamination, which are highly relevant to the windings temperature rise, are optimized analytically. The analytical results are verified by finite element analysis (FEA) and experiments. The maximum error between the analytical and the FEA results is 4%. The errors between the analytical and measured windings temperature rise are less than 8%. It can be proved that the method can obtain the optimal design accurately to reduce the winding temperature rise. Quanwu Li, Manfeng Dou, Bo Tan, Haitao Zhang, and Dongdong Zhao Copyright © 2016 Quanwu Li et al. All rights reserved. Suppression of Supersonic Cavity Oscillations Using Pulsed Upstream Mass Injection Mon, 10 Oct 2016 14:07:47 +0000 http://www.hindawi.com/journals/ijae/2016/6702385/ Pulsed upstream mass injection is examined to suppress supersonic cavity oscillations. The efficiency and physics of the noise control are investigated by large-eddy simulations of a turbulent flow (, ) past a rectangular cavity with a length-to-depth ratio of 2. Results show that the pulsed mass injection behaves less effectively in reducing the cavity oscillations than the steady one. The primary reason is that the pulsed mass injection is ineffective in lifting up the cavity shear layer and in suppressing the turbulent fluctuations in the shear layer. It concluded that breakup of the large-scale vorticial structures into a smaller length scale reveals direct links existing between the large-scale vortices and the radiation of the cavity resonances. Weipeng Li Copyright © 2016 Weipeng Li. All rights reserved. Numerical and Experimental Investigation of Near-Field Mixing in Parallel Dual Round Jets Sun, 09 Oct 2016 07:33:41 +0000 http://www.hindawi.com/journals/ijae/2016/7935101/ Parallel underexpanded round jets system has been widely used in engineering applications, and the flow field structures are very complex because of the jets interaction. In this paper, we studied the near-field mixing phenomenon in parallel dual underexpanded jets numerically by solving the Reynolds-Averaged Navier-Stokes Equations. The numerical results agree well with experimental data acquired by particle image velocimetry. Similar to plane jets, to some degree, two round jets are deflected towards the dual nozzle symmetry plane; the flow field can also be divided into three regions. Meanwhile, attempts have been made to predict merge point and combine point locations on certain cross profile of computational domain by correlating them with jet spacing and jet pressure ratio. The jet spacing plays an important role in jets interaction, and jet interaction decreases with the increase in jet spacing. The jets interaction in terms of merge (combine) point and pressure varies significantly while the jet spacing differs. Additionally, as pressure ratio increases, the effect of jet interaction decreases, and the merge (combine) point location moves downstream. Xie Zheng, Xie Jian, Jiang Wei, and Du Wenzheng Copyright © 2016 Xie Zheng et al. All rights reserved. Azimuth and Elevation Dynamic Tracking of UAVs via 3-Axial ULA and Particle Filtering Wed, 21 Sep 2016 09:17:07 +0000 http://www.hindawi.com/journals/ijae/2016/7630950/ Unmanned Aerial Vehicles (UAVs) localization has become crucial in recent years, mainly for navigation or self-positioning and for UAV based security monitoring and surveillance. In this paper, azimuth and elevation radio positioning of UAVs are considered. The localization is based on multiple differential phase-of-arrival measures exploiting a 3-Axial Uniform Linear Array of antennas. An ad hoc particle filtering algorithm is applied to improve the positioning performance using a dynamic motion model. A novel adaptive algorithm, namely, Particles Swarm Adaptive Scattering (PSAS), is proposed to increment the algorithm stability and precision. To assess performance a Confined Area Random Aerial Trajectory Emulator (CARATE) algorithm has been developed to generate actual paths of flying UAVs. The algorithm performance is compared with the baseline method and with the average trajectory Cramér Rao lower bound to show the effectiveness of the proposed algorithm. Andrea Papaiz and Andrea M. Tonello Copyright © 2016 Andrea Papaiz and Andrea M. Tonello. All rights reserved. Dynamic Rocker-Bogie: Kinematical Analysis in a High-Speed Traversal Stability Enhancement Tue, 20 Sep 2016 11:27:34 +0000 http://www.hindawi.com/journals/ijae/2016/5181097/ The rocker-bogie suspension system has robust capabilities to deal with uneven terrain because of its distributing of the payload over its six wheels uniformly, while there is one major shortcoming to high-speed traversal over the planar terrain. This paper proposes a new dynamic rocker-bogie suspension system with two modes of operation: it can expand the span of the rocker-bogie support polygon to increase travel rate when the terrain is planar; and it can switch to its original configuration to move by low speed when it is faced with rough terrain. The analysis on dynamic stability margin and kinematical simulation on the two operating modes of rocker-bogie are employed to analyze and verify the rationality and effectiveness of the modification in the structure. Sunxin Wang and Yan Li Copyright © 2016 Sunxin Wang and Yan Li. All rights reserved. Proper Orthogonal Decomposition as Surrogate Model for Aerodynamic Optimization Sun, 18 Sep 2016 08:50:36 +0000 http://www.hindawi.com/journals/ijae/2016/8092824/ A surrogate model based on the proper orthogonal decomposition is developed in order to enable fast and reliable evaluations of aerodynamic fields. The proposed method is applied to subsonic turbulent flows and the proper orthogonal decomposition is based on an ensemble of high-fidelity computations. For the construction of the ensemble, fractional and full factorial planes together with central composite design-of-experiment strategies are applied. For the continuous representation of the projection coefficients in the parameter space, response surface methods are employed. Three case studies are presented. In the first case, the boundary shape of the problem is deformed and the flow past a backward facing step with variable step slope is studied. In the second case, a two-dimensional flow past a NACA 0012 airfoil is considered and the surrogate model is constructed in the (Mach, angle of attack) parameter space. In the last case, the aerodynamic optimization of an automotive shape is considered. The results demonstrate how a reduced-order model based on the proper orthogonal decomposition applied to a small number of high-fidelity solutions can be used to generate aerodynamic data with good accuracy at a low cost. Valentina Dolci and Renzo Arina Copyright © 2016 Valentina Dolci and Renzo Arina. All rights reserved. Formation Control for Unmanned Aerial Vehicles with Directed and Switching Topologies Tue, 06 Sep 2016 15:40:38 +0000 http://www.hindawi.com/journals/ijae/2016/7657452/ Formation control problems for unmanned aerial vehicle (UAV) swarm systems with directed and switching topologies are investigated. A general formation control protocol is proposed firstly. Then, by variable transformation, the formation problem is transformed into a consensus problem, which can be solved by a novel matrix decomposition method. Sufficient conditions to achieve formation with directed and switching topologies are provided and an explicit expression of the formation reference function is given. Furthermore, an algorithm to design the gain matrices of the protocol is presented. Finally, numerical simulations are provided to illustrate the effectiveness of the theoretical results. Yahui Qi, Shaolei Zhou, Yuhang Kang, and Shi Yan Copyright © 2016 Yahui Qi et al. All rights reserved. Dynamics and Control of a Tethered Satellite System Based on the SDRE Method Sun, 04 Sep 2016 12:33:59 +0000 http://www.hindawi.com/journals/ijae/2016/3610507/ This paper presents the nonlinear dynamic modeling and control of a tethered satellite system (TSS), and the control strategy is based on the state-dependent Riccati equation (SDRE). The TSS is modeled by a two-piece dumbbell model, which leads to a set of five nonlinear coupled ordinary differential equations. Two sets of equations of motion are proposed, which are based on the first satellite and the mass center of the TSS. There are two reasons to formulate the two sets of equations. One is to facilitate their mutual comparison due to the complex formulations. The other is to provide them for different application situations. Based on the proposed models, the nonlinear dynamic analysis is performed by numerical simulations. Besides, to reduce the convergence time of the librations of the TSS, the SDRE control with a prescribed degree of stability is developed, and the illustrative examples validate the proposed approach. Yong-Lin Kuo Copyright © 2016 Yong-Lin Kuo. All rights reserved. A Terminal Guidance Law Based on Motion Camouflage Strategy of Air-to-Ground Missiles Tue, 30 Aug 2016 08:23:26 +0000 http://www.hindawi.com/journals/ijae/2016/9218754/ A guidance law for attacking ground target based on motion camouflage strategy is proposed in this paper. According to the relative position between missile and target, the dual second-order dynamics model is derived. The missile guidance condition is given by analyzing the characteristic of motion camouflage strategy. Then, the terminal guidance law is derived by using the relative motion of missile and target and the guidance condition. In the process of derivation, the three-dimensional guidance law could be designed in a two-dimensional plane and the difficulty of guidance law design is reduced. A two-dimensional guidance law for three-dimensional space is derived by bringing the estimation for target maneuver. Finally, simulation for the proposed guidance law is taken and compared with pure proportional navigation. The simulation results demonstrate that the proposed guidance law can be applied to air-to-ground missiles. Chang-sheng Gao, Jian-qing Li, and Wu-xing Jing Copyright © 2016 Chang-sheng Gao et al. All rights reserved.