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A customer selection and vehicle scheduling model for moving companies

TRANSPORTATION LETTERS-THE INTERNATIONAL JOURNAL OF TRANSPORTATION RESEARCH 2020年第9期12卷 613-622页

作者： Yan, Shangyao Chu, James C. Hung, Wei-Che Natl Cent Univ Dept Civil Engn Taoyuan Taiwan Natl Taiwan Univ Dept Civil Engn 1 Roosevelt Rd Taipei 106 Taiwan

This study develops a model for customer selection and vehicle scheduling with time windows for moving companies. To reflect the actual operations of moving companies, the proposed model employs two major processes to extend the traditional vehicle routing models. First, loading and unloading activities of moving vehicles are explicitly modeled using the technique of time-space networks. Second, moving companies are flexible in selecting customers, thereby possibly maximizing the profit of companies. The model is formulated as an integer multi-commodity network with side constraints. A decomposition-based solution algorithm is developed to solve the problem efficiently. Results of a case study indicate that the proposed methodology efficiently generates reasonable plans of customer selection and vehicle scheduling. Sensitivity analysis shows that the proposed model properly responds to the change in critical parameters. Therefore, the proposed methodology has a strong potential to improve the operations and profitability of moving companies.

关键词： Moving company time-space network multi-commodity network flow model solution algorithm

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Plastic analysis of complex microstructure composites using the generalized method of cells

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AIAA JOURNAL 1999年第4期37卷 482-488页

作者： Orozco, CE Pindera, MJ Univ Virginia Dept Civil Engn Charlottesville VA 22903 USA

A recently developed computationally efficient implementation of the Generalized Method of Cells is extended here to deal with plasticity problems. The new formulation can be used to perform linear elastic and plastic micromechanical analysis of composites with complex microstructures. It makes use of a tangent plasticity matrix approach as opposed to an initial stiffness matrix approach employed in the original Generalized Method of Cells. This tangent stiffness matrix approach makes it possible to perform plastic analyses of composites with microstructures that require a high-resolution, cell-subcell model. To demonstrate the capabilities of the new formulation, it is applied to the problem of determining the influence of fiber shape and fiber architecture on the plastic behavior of two-phase unidirectional composites. Some results from previous studies on this subject are confirmed. New results that could not be obtained with previous implementations are also reported. Problems modeled with up to 10,000 subcells are presented.

关键词： Microstructure Stiffness Matrices Plasticity Elastic Properties Residual Stress Material Properties Fiber Volume Fraction Aspect Ratio Boundary Value Problems solution algorithm

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A Novel Grid Point Approach for Efficiently Solving the Constellation-to-Ground Regional Coverage Problem

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IEEE ACCESS 2018年 6卷 44445-44458页

作者： Song, Zhiming Dai, Guangming Wang, Maocai Chen, Xiaoyu China Univ Geosci Sch Comp Wuhan 430074 Hubei Peoples R China China Univ Geosci Hubei Key Lab Intelligent Geoinformat Proc Wuhan 430074 Hubei Peoples R China

The constellation-to-ground coverage problem is a basic and important problem in satellite applications. The grid-point approach (GPA) is one of the most commonly used approaches to solving this problem. However, this approach also has some serious drawbacks. A group of strategies that can improve or overcome the drawbacks of this approach are proposed. The spatial and temporal characteristics of the GPA were analyzed, and a strategy that can compute the upper and lower bounds of the result was given. This strategy can not only acquire the result but can also yield the error range of the result. In addition, a strategy that uses low-precision results to compute a high-precision result is proposed. Simulation experiments of different types of coverage problems were conducted, and the results show that these strategies are effective.

关键词： Satellite Constellation Coverage Problem Grid Point Approach solution algorithm

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Drag Minimization Based on the Navier-Stokes Equations Using a Newton-Krylov Approach

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AIAA JOURNAL 2015年第6期53卷 1555-1577页

作者： Osusky, Lana Buckley, Howard Reist, Thomas Zingg, David W. Univ Toronto Toronto ON M3H 5T6 Canada Univ Toronto Inst Aerosp Studies Toronto ON M3H 5T6 Canada

A methodology is presented for performing numerical aerodynamic shape optimization based on the three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations. An initial multiblock structured mesh is first fit with B-spline volumes that form the basis for a hybrid mesh movement scheme that is tightly integrated with the geometry parameterization based on B-spline surfaces. The RANS equations and the one-equation Spalart-Allmaras turbulence model are solved in a fully coupled manner using an efficient parallel Newton-Krylov algorithm with approximate-Schur preconditioning. Gradient evaluations are performed using the discrete-adjoint approach with analytical differentiation of the discrete flow and mesh movement equations. The overall methodology remains robust even in the presence of large shape changes. Several examples of lift-constrained drag minimization are provided, including a study of the common research model wing geometry, a wing-body-tail geometry with a prescribed spanwise load distribution, and a blended-wing-body configuration. An example is provided that demonstrates that a wing optimized based on the Euler equations exhibits substantially inferior performance when subsequently analyzed based on the RANS equations relative to a wing optimized based on the RANS equations.

关键词： Navier Stokes Equations Aerodynamic Shape Optimization Reynolds Averaged Navier Stokes Blended Wing Body Configurations Tail Geometry Euler Equations Spalart Allmaras Turbulence Model solution algorithm Aerodynamic Performance Aircraft Configurations

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ANALYTIC FOURIER-TRANSFORM FOR A CLASS OF FINITE-TIME CONTROL-PROBLEMS

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1985年第4期8卷 539-541页

作者： TURNER, JD CHUN, HM CHARLES STARK DRAPER LAB INC CAMBRIDGEMA 02139

A computationally efficient closed-form algorithm for obtaining the Fourier transform of finite-time open-loop and closed-loop control problems is presented. The requirements of the algorithm include the evaluation of a single matrix exponential for the dynamics of the time-varying control, the solution for either the right and left eigenvectors or a real Schur decomposition of the constant control dynamics matrix, the solution for the reducing subspace transformation vector, and the evaluation of a single scalar complex exponential. An example of an application of the algorithm is given.

关键词： Numerical Integration Spacecraft Attitude Euler Angles State Space Representation Linear Quadratic Gaussian Frequency Domain Multivariable Control solution algorithm Stochastic Control Optical Telescopes

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TRILATERATION AND EXTENSION TO GLOBAL POSITIONING SYSTEM NAVIGATION

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1986年第6期9卷 715-717页

作者： FANG, BT Analytic Sciences Corp. McLean VA

Trilateration, the determination of navigational position on the basis of simultaneous ranging from three trackers, is usually conducted by means of the Escobal (1965) algorithm; this method is, however, noted to be unnecessarily complex. Simple explicit solutions are presently obtained by referencing the navigation position to the plane defined by the three trackers. The trilateration method is presently extended to GPS navigation, which requires the determination of time as well as position. (O.C.)

关键词： GPS Earth Iterative solution solution algorithm Earth Satellites Doppler Shift

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Optimal simultaneous pairwise conflict resolution maneuvers in air traffic management

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2002年第4期25卷 815-818页

作者： Clements, JC Dalhousie Univ Dept Math & Stat Halifax NS B3H 3J5 Canada

The optimal simultaneous pairwise conflict resolution maneuvers in air traffic management were discussed. A simple time-stepping algorithm was presented that would detect potential conflicts and resolve them by computing the globally optimal steering programs for aircrafts in real time. The algorithm derived could prove to be a useful tool in exploring the design of a comprehensive conflict detection and avoidance system.

关键词： Air Traffic Management Costate Equation Airspeed Aircraft Separation Lagrange Multipliers Cartesian Coordinate System Standard Rate Turn solution algorithm Guidance System Computing

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Finite element-based boundary treatment in the hybrid particle method

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AIAA JOURNAL 2005年第7期43卷 1626-1628页

作者： Huang, H Saigal, S Dyka, CT Univ S Florida Tampa FL 33620 USA USN Ctr Surface Warfare Dahlgren VA 22448 USA

Finite element (FE)-based motion points are developed for use in particlemethods. These motion points are advantageous for boundary treatment in the hybrid particle *** resulting approach considers boundary motion points as finite element nodes, whereas theneighboring stress points are considered as the integration points of an explicit finite elementmethod (FEM) formulation. The stability of employing FE-based motion points is discussed. Numericalresults are presented to demonstrate the feasibility, accuracy, and stability of the presentdevelopment. These developments can facilitate methodologies to combine the hybrid particle methodand the explicit FEM in a single analysis.

关键词： Shape Functions Specific Volume Conservation Equations Elastic Modulus Plane Strain Smoothed Particle Hydrodynamics Predictor Corrector Method Conservation of Mass solution algorithm Work Hardening

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Unified formulation for compressible-incompressible flow simulation with mesh adaptation

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AIAA JOURNAL 2001年第12期39卷 2425-2427页

作者： Turgeon, É Pelletier, D Ecole Polytech Dept Genie Mech Montreal PQ H3C 3A7 Canada

Proposes a pressure-based formulation capable of handling compressible and incompressible flows. Temperature dependence of air properties; Role of absolute pressure and pressure differences; Application of a standard ... 详细信息

关键词： Incompressible Flow Freestream Conditions Neumann Boundary Condition Skin Friction Apparent Viscosity Compressibility Effect Continuity Equation Wall Temperature Thermal Conductivity solution algorithm

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STABILITY OF THE THIN-JET MODEL OF THE UNSTEADY JET FLAP

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AIAA JOURNAL 1985年第7期23卷 1118-1120页

作者： PULLIN, DI SIMMONS, JM University of Queensland Brisbane Australia

A jet flap results if air is ejected from a spanwise slot at or near the trailing edge of an airfoil. It produces lift both by the component of thrust in the lift direction and by the modification of circulation around the airfoil. The steady jet flap, for which flow parameters are constant, has received considerable attention because of interest in V/STOL aircraft.

关键词： Jet Flaps Starting Vortex Incompressible Flow Kutta Condition Freestream Linear Interpolation Numerical Stability Bernoulli's Equation solution algorithm Helicopter Rotor

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