查看更多>>摘要：The joined-wing configuration reduces induced drag and structural weight by connecting the rear wing to the front wing.In addition,the rear wing can replace the role of the horizontal tail of a conventional aircraft,thus eliminating the aerodynamic drag and weight associated with the horizontal tail.This particular shape creates a highly coupled relationship between aerodynamics and structure,which must be fully considered during the overall design process to enhance aircraft performance.In this research,an aero-structural design model of the joined-wing aircraft is con-structed based on high-fidelity computational fluid dynamics and structural finite element methods.The model is able to obtain accurate aerodynamic loads for the non-planar wing and to simulate the statically indeterminate structure of the closed wing configuration.The influence of the joined-wing shape parameters on the aerodynamic and structural disciplines,as well as the influence of geomet-ric nonlinear characteristics,deformation constraints and buckling constraints on the structural weight are all taken into consideration.The model is applied to complete the aero-structural design optimization of a high-altitude long-endurance joined-wing aircraft,and wind tunnel tests are con-ducted.The test results verify the credibility of the design model proposed and the validity of the design environment.
查看更多>>摘要：Future Sixth-Generation(6G)mobile communication networks extremely require the global connectivity and the ground Base Stations(BSs)are difficult to develop in some specific areas,such as mountainous areas.Therefore,the aerial networks are the key framework for the future communications,in which the aerial vehicle could act as the access point.Additionally,Mobile Edge Computing(MEC)is also essential to enhance the data processing capabilities of aer-ial networks.In this paper,we study a comprehensive communication-computation resource man-agement problem for jointly optimizing user pairing,power and time allocation in the MEC aided Cognitive Radio(CR)aerial networks,namely CR-MEC aerial networks.Explicitly,this multilevel optimization problem could be decomposed into the user pairing and power allocation as well as time allocation sub-problems.In the conceived CR-MEC aerial networks,we propose a User Pair-ing and Computation Offloading Management Algorithm(UPCOMA)based on three-sided match-ing theory,aiming to minimize the system's energy consumption.At the first step of UPCOMA,multiple Primary Users(PUs)and Cognitive Users(CUs)on the ground negotiate to each other with the suitable power allocation coefficients and construct the stable user pairs.Moreover,the stable user pairs would match to a high altitude platform who act as the base station,which is for appropriately allocating Transmission Time Slots(TSs)at the second step of UPCOMA.Addi-tionally,a hybrid offloading mode is proposed in our conceived networks in order to support ground users to offload their tasks adaptively according to their individual deadlines.Furthermore,the simulation results reveal that the relative performance of UPCOMA is close to that of the Brute-Force Search Algorithm(BFSA)with low complexity.Meanwhile,the hybrid offloading mode with less energy consumption supports much more ground user pairs to offload tasks com-pared to the binary mode.
查看更多>>摘要：Confined spaces such as polar regions,deep earth and deep ocean are crucial navigation scenarios where traditional navigation techniques have difficulty in obtaining external signals for positioning.The cosmic ray muons,which carry the spatial and energetic information,are easy to penetrate these confined spaces.Therefore,the unique muon characteristic provides a new per-spective to estimate detector position,which can be considered using in confined spaces navigation.In this paper,a well-developed theory of muon navigation is established by combining a muon pseudorange measurement method.Moreover,an Equivalent Velocity Calculation Model(EVCM)and a Muon Sequence Matching Technology(MSMT)are proposed.The first model corrects flight pseudorange error caused by the relativistic energy loss and the second technology compensates the random error in pseudorange measurement.Further,a series of simulations are performed to ana-lyze the muon events number which can be received by detector in different scenarios with the vari-ations of zenith angle,detector area,varied detector plates gap,and muon flight distance.Meanwhile,the simulation results demonstrate that the muon navigation update rate every 10 min-utes can reach 5.989 in confined spaces at 100 m,and further pseudorange error analysis indicates that the meter-level positioning accuracy can be acquired.Finally,we construct a muon coincidence measurement scheme and verify that the laws of the muon positioning system for high-energy muons are consistent with the simulation results.
查看更多>>摘要：This paper proposes a robust vector tracking loop structure based on potential bias anal-ysis.The influence of four kinds of biases on the existing two implementations of Vector Tracking Loops(VTLs)is illustrated by theoretical analysis and numerical simulations,and the following findings are obtained.Firstly,the initial user state bias leads to steady navigation solution bias in the relative VTL,while new measurements can eliminate it in the absolute VTL.Secondly,the initial code phase bias is transferred to the following navigation solutions in the relative VTL,while new measurements can eliminate it in the absolute VTL.Thirdly,the user state bias induced by erroneous navigation solution of VTLs can be eliminated by both of the two VTLs.Fourthly,the multipath/NLOS likely affects the two VTLs,and the induced tracking bias in the duration of the multipath/NLOS would decrease the performance of VTLs.Based on the above analysis,a robust VTL structure is proposed,where the absolute VTL is selected for its robustness to the two kinds of initialization biases;meanwhile,the instant bias detection and correction method is used to improve the performance of VTLs in the duration of the multipath/NLOS.Numerical sim-ulations and experimental results verify the effectiveness of the proposed robust VTL structure.
查看更多>>摘要：This paper develops a novel Neural Network(NN)-based adaptive nonsingular practical predefined-time controller for the hypersonic morphing aircraft subject to actuator faults.Firstly,a novel Lyapunov criterion of practical predefined-time stability is established.Following the pro-posed criterion,a tangent function based nonsingular predefined-time sliding manifold and the con-trol strategy are developed.Secondly,the radial basis function NN with a low-complexity adaptation mechanism is incorporated into the controller to tackle the actuator faults and uncer-tainties.Thirdly,rigorous theoretical proof reveals that the attitude tracking errors can converge to a small region around the origin within a predefined time,while all signals in the closed-loop sys-tem remain bounded.Finally,numerical simulation results are presented to verify the effectiveness and improved performance of the proposed control scheme.
Muhammed S.PARANCHEERIVILAKKATHILJafar S.PILAKKADANRafic M.AJAJMohammadreza AMOOZGAR...
436-463页
查看更多>>摘要：This paper reviews the various control algorithms and strategies used for fixed-wing mor-phing aircraft applications.It is evident from the literature that the development of control algo-rithms for morphing aircraft technologies focused on three main areas.The first area is related to precise control of the shape of morphing concepts for various flight conditions.The second area is mainly related to the flight dynamics,stability,and control aspects of morphing aircraft.The third area deals mainly with aeroelastic control using morphing concepts either for load alleviation purposes and/or to control the instability boundaries.The design of controllers for morphing air-craft/wings is very challenging due to the large changes that can occur in the structural,aerody-namic,and inertial characteristics.In addition,the type of actuation system and actuation rate/speed can have a significant effect on the design of such controllers.The aerospace community is in strong need of such a critical review especially as morphing aircraft technologies move from fun-damental research at a low Technology Readiness Level(TRL)to real-life applications.This critical review aims to identify research gaps and propose future directions.In this paper,research activi-ties/papers are categorized according to the control strategy used.This ranges from simple Propor-tional Integral Derivative(PID)controllers at one end to complex robust adaptive controllers and deep learning algorithms at the other end.This includes analytical,computational,and experimen-tal studies.In addition,the various dynamic models used and their fidelities are highlighted and dis-cussed.
查看更多>>摘要：In this paper,the attitude tracking and load relief control problems against wind distur-bances and uncertain aerodynamics as well as the engine thrust of launch vehicles are studied.Firstly,a framework of Compensated Acceleration Feedback based Active Disturbance Rejection Control(CAF-ADRC)is established to achieve both desired attitude tracking and load relief per-formances.In particular,the total disturbance that includes the effects caused by both aero-coefficient perturbations and disturbances is estimated by constructing an Extended State Observer(ESO)to achieve attitude tracking.Furthermore,combined with the normal acceleration due to the engine thrust,the accelerometer measurement is also compensated to enhance the load relief effect.Secondly,the quantitative analysis of ESO and the entire closed-loop system are studied.It can be concluded that the desired attitude tracking and load relief performances can be achieved simulta-neously under the proposed approach.Besides,tuning laws of the proposed approach are system-atically given,which are divided into ESO,Proportional Derivative(PD)and Compensated Acceleration Feedback(CAF)modules.Moreover,the performances under CAF-ADRC approach can be better than those under CAF based PD(CAF-PD)approach by tuning load relief gain.Finally,the approach presented is applied to a typical control problem of launch vehicles with wind disturbances and parameter uncertainties.
查看更多>>摘要：Hermetically Sealed Electromagnetic Relay(HSER),used in aviation and aerospace,demands high reliability due to its critical applications.Given its complex operating conditions,effi-cient thermal analysis is essential for optimizing reliability.The commonly used Finite Element Method(FEM)is often time-consuming and may not be efficient or adaptable for complex multi-dimensional system calculations and design processes.This paper introduces an analysis method for thermal networks based on matrix perspective technology,encompassing matrix trans-formation,backpropagation of the heat path model,temperature rise calculation,solution compar-ison,and product implementation.Using the similarity theory of heat circuits,a basic thermal unit is established.Based on the fundamental connection between key components,a thermal network for a typical HSER is designed.An experimental system is set up,and the thermal network model's accuracy is confirmed using test data.Employing the topology analysis method,the topology of the thermal network is analyzed under both coil-energized and de-energized states.Potential thermal paths are identified,leading to optimized solutions for the HSER.Utilizing these solutions,the ther-mal path matrix topology model is backpropagated to the thermal path for temperature rise calcu-lations.When compared to prototype HSER test data,the efficiency and accuracy of this matrix topology-based analysis method are confirmed.
查看更多>>摘要：Intelligent Adaptive Control(AC)has remarkable advantages in the control system design of aero-engine which has strong nonlinearity and uncertainty.Inspired by the Nonlinear Autoregressive Moving Average(NARMA)-L2 adaptive control,a novel Nonlinear State Space Equation(NSSE)based Adaptive neural network Control(NSSE-AC)method is proposed for the turbo-shaft engine control system design.The proposed NSSE model is derived from a special neural network with an extra layer,and the rotor speed of the gas turbine is taken as the main state variable which makes the NSSE model be able to capture the system dynamic better than the NARMA-L2 model.A hybrid Recursive Least-Square and Levenberg-Marquardt(RLS-LM)algo-rithm is advanced to perform the online learning of the neural network,which further enhances both the accuracy of the NSSE model and the performance of the adaptive controller.The feedback correction is also utilized in the NSSE-AC system to eliminate the steady-state tracking error.Sim-ulation results show that,compared with the NARMA-L2 model,the NSSE model of the turbo-shaft engine is more accurate.The maximum modeling error is decreased from 5.92％to 0.97％when the LM algorithm is introduced to optimize the neural network parameters.The NSSE-AC method can not only achieve a better main control loop performance than the traditional controller but also limit all the constraint parameters efficiently with quick and accurate switching responses even if component degradation exists.Thus,the effectiveness of the NSSE-AC method is validated.
查看更多>>摘要：Experimental and numerical investigations were performed to reveal the effect of pre-stress on the fatigue properties of FGH4097 so as to quantitatively evaluate the overspeed benefit of the disc of aeroengine.A corresponding experiment was performed to examine the effect of pre-stress on the fatigue life of FGH97.A complete model describing the fatigue properties of the pre-stressed notch specimen was proposed.After the modification of mean stress,stress gradient and prestressing treatment,the model is finally verified by fatigue test of presstressed notch specimens machined from FGH4097 with satisfactory accuracy and good engineering applicability.The new model highlights that for the variable fatigue loads,the introduction of appropriate prestress is expected to benefit to the notch specimens and certainly to the disc of aeroengine regards of their fatigue properties.Both the calculation method of fatigue life parameters and the prestress correc-tion model are proved to have good prediction accuracy.
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