Abstract
Drones are increasingly used in logistics delivery due to their low cost, high-speed and straight-line flight. Considering the small cargo capacity, limited endurance and other factors, this paper optimized the pickup and delivery vehicle routing problem with time windows in the mode of "truck+drone". A mixed integer programming model with the objective of minimizing transportation cost was proposed and an improved adaptive large neighborhood search algorithm is designed to solve the problem. In this algorithm, the performance of the algorithm is improved by designing various efficient destroy operators and repair operators based on the characteristics of the model and introducing a simulated annealing strategy to avoid falling into local optimum solutions. The effectiveness of the model and the algorithm is verified through the numerical experiments, and the impact of the "truck+drone" on the route cost is analyzed, the result of this study provides a decision basis for the route planning of "truck+drone" mode delivery.
Key Words
adaptive large neighborhood search algorithm; pick-up and delivery problem with time window; vehicle routing
Address
C.C. Hung: Faculty of National Hsin Hua Senior High School, Tainan, Taiwan
T. Nguyễn: Ha Tinh University, Dai Nai Ward, Ha Tinh City, Vietnam
C.Y. Hsieh: National Pingtung University Education School, No.4-18, Minsheng Rd., Pingtung City, Pingtung County 900391, Taiwan
Abstract
This paper presents the study of the effects of rigid-body motion simultaneously with the presence of the effects of temporal variation due to the existence of morphing speed on the aeroelastic stability of the two-stage telescopic wings, and hence this is the main novelty of this study. To this aim, Euler-Bernoulli beam theory is used to model the bending-torsional dynamics of the wing. The aerodynamic loads on the wing in an incompressible flow regime are determined by using Peters' unsteady aerodynamic model. The governing aeroelastic equations are discretized employing a finite element method based on the beam-rod model. The effects of rigid-body motion on the length-based stability of the wing are determined by checking the eigenvalues of system. The obtained results are compared with those available in the literature, and a good agreement is observed. Furthermore, the effects of different parameters of rigid-body such as the mass, radius of gyration, fuselage center of gravity distance from wing elastic axis on the aeroelastic stability are discussed. It is found that some parameters can cause unpredictable changes in the critical length and frequency. Also, paying attention to the fuselage parameters and how they affect stability is very important and will play a significant role in the design.
Key Words
aeroelastic stability; morphing aircraft; rigid body motion; two-stage; variable span wing
Address
Sayed Hossein Moravej Barzani and Hossein Shahverdi: Department of Aerospace Engineering, Amirkabir university of Technology, Tehran, Iran
Abstract
Free surface fluid oscillation in prolate spheroidal tanks has been investigated analytically in this study. This paper aims is to investigate the sloshing frequencies in spheroidal prolate tanks and compare them with conventional cylindrical and spherical containers to select the best tank geometry for use in space launch vehicles in which the volume of fuel is very high. Based on this, the analytical method (Fourier series expansion) and potential fluid theory in the spheroidal coordinate system are used to extract and analyze the governing differential equations of motion. Then, according to different aspect ratios and other parameters such as filling levels, the fluid sloshing frequencies in the spheroidal prolate tank are determined and evaluated based on various parameters. The natural frequencies obtained for a particular tank are compared with other literature and show a good agreement with these results. In addition, spheroidal prolate tank frequencies have been compared with sloshing frequencies in cylindrical and spherical containers in different modes. Results show that when the prolate spheroidal tank is nearly full and in the worst case when the tank is half full and the free fluid surface is the highest, the prolate spheroidal natural frequencies are higher than of spherical and cylindrical tanks. Therefore, the use of spheroidal tanks in heavy space launch vehicles, in addition to the optimal use of placement space, significantly reduces the destructive effects of sloshing.
Key Words
fourier series expansion; free surface oscillation; potential fluid theory; sloshing frequencies; spheroidal containers
Address
Mohammad Mahdi Mohammadi, Hojat Taei, Hamid Moosazadeh: Faculty of the Mechanic, Malek Ashtar University of Technology, Tehran, Iran
Mohammad Sadeghi: Department of Aerospace Engineering, Tarbiat Modares University, Tehran, Iran
Abstract
The paper evaluates the aerodynamic coefficients on a blunt-nose re-entry capsule with a conical crosssection followed by a cone-flare body. A computer code is developed to solve three-dimensional compressible inviscid equations for flow over a Space Recovery Experiment (SRE) configuration at different flare-cone half-angle at Mach 6 and angle of attack up to 5o, at 1o interval. The surface pressure variation is numerically integrated to obtain the aerodynamic forces and pitching moment. The numerical analysis reveals the influence of flare-cone geometry on the flow characteristics and aerodynamic coefficients. The numerical results agree with wind tunnel results. Increase of cone-flare angle from 25o to 35o results in increase of normal force slope, axial forebody drag, base drag and location of centre of pressure by 62.5%, 56.2% and 33.13%, respectively, from the basic configuration of the SRE of 25o.
Key Words
aerodynamic coefficients; base flow; computational fluid dynamics; hypersonic flow; re-entry vehicle; shock wave
Address
R.C. Mehta: Department of Aeronautical Engineering, Noorul Islam Centre for Higher Education, Kumaracoil 629180, India
E. Rathakrishnan: Department of Aerospace Engineering, Indian institute of Technology, Kanpur 208016, India
Abstract
This article introduces a formalism for the analysis of airplane trajectories on which the motion is determined by specifying the power of the engines. It explains a procedure to solve the equations of motion to obtain the value of the relevant flight parameters. It then enumerates the constraints that the dynamical abilities of the airplane impose on the amount of fuel used, the speed, the load factor, the lift coefficient, the positivity and upper boundedness of the power available. Examples of analysis are provided to illustrate the method proposed, with rectilinear and circular trajectories. Two very different types of airplanes are used in the examples: a Silver Fox-like small UAV and a common Cessna 182 Skylane.
Key Words
airplane equation of motion; airplane trajectory; automatic trajectory planning; circular trajectory; power control; rectilinear trajectory
Address
Gilles Labonté: Department of Mathematics and Computer Science, Royal Military College of Canada, Kingston, Ontario, Canada
Vincent Roberge, Mohammed Tarbouchi: Department of Electrical Engineering and Computer Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
