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Shape Exploration and Multidisciplinary Optimization Method of Semirigid Nearing Space Airships

JOURNAL OF AIRCRAFT 2022年第4期59卷 946-963页

作者： Tang, Jiwei Duan, Dengping Xie, Weicheng Shanghai Jiao Tong Univ Sch Aeronaut & Astronaut Shanghai 200240 Peoples R China Aerosp Syst Engn Shanghai Shanghai 201109 Peoples R China

This paper describes a shape exploration and multidisciplinary optimization method of unconventional semirigid nearing space airships. The approach includes several improved mutually interacting disciplines, viz., aerodynamics, structure, propulsion, pressure control, energy, avionics, and electric cable. To describe the nonstreamlined envelope shape of the semirigid nearing space airships, a parameterization methodology involving 12 variables is proposed. And an aerodynamics surrogate model is established using the results of computational fluid dynamics simulations. To obtain the configurations of airship, detailed improved subsystem models are proposed. And a combinatorial optimization strategy is established to search for the optimal solutions. The approach can directly obtain the optimal general configurations such as envelope shape and size, as well as parameters of subsystems such as the required number of valve and air blowers. Optimization results show that the payload capacity increases 16.8% for the airship with same volume. Besides, effects of payload capacity of mass and power are investigated. Finally, sensitivity analysis on the subsystem parameters shows that the volume of semirigid airship is most sensitive to five parameters, viz., areal density of outer envelope, areal density of inner envelope, energy density of lithium battery, propulsion efficiency, and density of carbon fiber material, in turn.

关键词： Hybrid Airship Energy Density Drag Coefficient Computational Fluid Dynamics Simulation Surrogate Model Avionics Systems Lithium Battery Sensitivity Analysis Reynolds Averaged Navier Stokes sequential quadratic programming

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Aerodynamic optimization of supersonic transport wing using unstructured adjoint method

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AIAA JOURNAL 2001年第6期39卷 1011-1020页

作者： Kim, HJ Sasaki, D Obayashi, S Nakahashi, K Tohoku Univ Dept Aeronaut & Space Engn Sendai Miyagi 980 Japan

An aerodynamic design method has been developed by using a three-dimensional Euler code and an adjoint code with a discrete approach. The method is applied to wing design problems of supersonic transports with wing-body-nacelle and wing-body configurations. Hicks-Henne shape functions are adopted for the surface geometry perturbation, and the elliptic equation method is employed for the interior grid modification during the design process. Interior grid sensitivities are neglected except those for design parameters associated with a body translation such as nacelles. The sequential quadratic programming method is used to minimize the drag with constraints on the lift and airfoil thickness. Successful design results confirm validity and efficiency of the present design method.

关键词： Supersonic Transports Nacelles Freestream Mach Number sequential quadratic programming Shape Functions Airfoil Thickness Sensitivity Analysis Unstructured Grid Euler Equations Turbulence Models

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Design of optimal sampling times for pharmacokinetic trials via spline approximation

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TURKISH JOURNAL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES 2010年第6期18卷 1019-1030页

作者： Asyali, Musa Hakan Zirve Univ Dept Elect & Elect Engn TR-27260 Kizilhisar Gaziantep Turkey

Understanding and comparison of different drug delivery formulations are based on pharmacokinetic parameters (PKP) such as area under curve, maximum concentration, and time to reach maximum concentration. Accurate estimation of PKP is of critical importance in capturing drug absorption and elimination characteristics and in reaching bioequivalence decisions. Since PKP are estimated from a limited number of samples, the timing of the samples directly influences the accuracy of estimation. Optimization of the sampling times may not only increase the accuracy of PKP estimation, but also reduce the number of samples to be drawn, which in turn lessens the inconvenience to the subjects and the cost of the study. In this study, as an alternative to conventional piece-wise linear approximation, we proposed cubic spline approximation to the time-concentration curve and also introduced a global optimality criterion that focuses on the closeness of all the pharmacokinetic parameter estimators to their true values simultaneously. By minimizing the criterion function over sampling times and watching the regulatory practice/guidance for sample collection, we designed optimal sampling times that can be used in pharmacokinetic studies. We demonstrated that using our approach it is possible to obtain more accurate estimates of PKP with fewer samples.

关键词： Pharmacokinetic parameters optimal sampling time design spline approximation sequential quadratic programming

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Optimal operation of a hospital power plant

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ENERGY AND BUILDINGS 2002年第10期34卷 1055-1065页

作者： van Schijndel, AWM Eindhoven Univ Technol Dept Architecture Bldg Grp Bldg Phys FAGO NL-5600 MB Eindhoven Netherlands

In this paper the operation of an Academic Hospital installation is evaluated by simulation and optimization on a yearly base. A mathematical model has been developed, which is based on energy balances of the installed components. Manufacturer specifications of the components are used for calculating the parameters. The model is formulated using vector equations. Advantages of this type of model formulations are presented. The tools used for optimization are custom developed back-tracking methods for calculating a good starting point and a SQP optimization tool for finding the optimum. Detailed control strategies are calculated for three types of optimization strategies simulated. The simulation results show the impact of the choice of a control strategy on the optimized operation. The results are also applicable for on-line setpoint optimization. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： absorption chiller sequential quadratic programming combined heat and power

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Inventory control for the closed-loop supply chain with technological progress and planned shortages

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EUROPEAN JOURNAL OF INDUSTRIAL ENGINEERING 2022年第2期16卷 143-168页

作者： Chen, Shih-Pin Lin, Yu-Min Natl Chung Cheng Univ Dept Business Adm 168 Univ Rd Ming Hsiung Chiayi Taiwan

The impact of Industry 4.0 has received much attention in academic and practice fields. Therefore, understanding the effects of technological progress in production on closed-loop supply chain (CLSC) inventory management is critical. In view of profit efficiency, this paper investigates the effects of technological progress in production on inventory policies in a CLSC considering planned shortages. A CLSC production-inventory model is proposed to jointly determine sale and collection prices and production time points. The representative numerical results show that technological progress in manufacturing inconsistently has a positive impact on the NPU because the total quantity produced and cycle length vary. The impact of technological progress may be greater in the manufacturing process than in the remanufacturing process. The results can aid production managers in finding optimal production-inventory strategies considering technological progress and planned shortages. Additionally, the results provide useful information regarding the impact of technological progress in selecting investment targets. [Received: 5 August 2020;Accepted: 16 March 2021]

关键词： inventory technological progress remanufacturing sequential quadratic programming supply chain management learning effects

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Application of SQP algorithm for fluorescence tomography with the time-domain equation of radiative transfer

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JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2017年 193卷 21-30页

作者： Qiao, Yao-Bin Qi, Hong Ren, Ya-Tao Sun, Jian-Ping Ruan, Li-Ming Harbin Inst Technol Sch Energy Sci & Engn 92West Dazhi St Harbin 150001 Peoples R China

A reconstruction scheme for the fluorescence tomography is investigated based on the time-domain radiative transfer equation (TD-RTE). Two coupled TD-RTES, which can provide considerable measurement data, are used as the forward model and solved by the discrete ordinate method. The sequential quadratic programming (SQP) is employed to build the reconstruction scheme for solving the inverse problem. The gradient of objective function is calculated efficiently by the adjoint equation technique. Considering the ill-posed nature of the inverse problem, the regularization term based on the generalized Gaussian Markov random field (GGMRF) model is adopted to enhance the reconstructed image. Influence of the initial guess, contrast, noisy data, and shape of the fluorescent target are analyzed. Simulated results show that the proposed algorithm performs efficiently and accurately on reconstructing the distribution of the fluorescence yield. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Time-domain equation of radiative transfer Fluorescence tomography Adjoint equation sequential quadratic programming

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Variational Model for Optimization of Finite-Burn Escape Trajectories Using a Direct Method

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2012年第2期35卷 598-608页

作者： Ocampo, Cesar A. Mathur, Ravishankar Univ Texas Austin Dept Aerosp Engn & Engn Mech Austin TX 78712 USA

A variational model is used to obtain the necessary gradient information for a multiple finite-burn trajectory problem. The augmented state vector includes position, velocity, mass, and control variables such as thrust magnitude, and the variables that describe the time evolution of the thrust direction unit vector. The augmented state vector and its associated state equation are used in the variational model to formulate analytical expressions for the gradients of the problem functions with respect to the problem variables. A general finite-burn trajectory problem is formulated for an inertially fixed thrust vector steering model and a fixed-plane linearly varying thrust vector steering model that constrains the thrust vector to be normal to a rotation axis, which itself is part of the control variable set. Both steering models are used in the optimization of a three-finite-burn lunar-escape-trajectory example, using a direct optimization method with explicit numerical integration. The performance of the optimization procedure is compared for both thrust vector steering models, using variational gradients and standard numerical finite difference gradients. The ability to obtain the most accurate gradient information for the direct optimization of simple finite-burn thrust steering models is a motivation of the current study.

关键词： Exhaust Velocity Hohmann Transfer Propellant sequential quadratic programming Finite Difference Method Earth Trajectory Optimization Computing Crew Exploration Vehicle Numerical Integration

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Efficient motion planning and control for automated lane change considering road adhesion coefficient

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INTERNATIONAL JOURNAL OF VEHICLE DESIGN 2024年第3-4期95卷 320-347页

作者： Ding, Haitao Song, Ziyu Zhang, Jianwei Xu, Nan Gao, Shaoshuai Zhao, Chunlai Jilin Univ State Key Lab Automot Simulat & Control Changchun 130000 Jilin Peoples R China China Aerosp Times Feihong Technol Co Ltd Beijing 100854 Peoples R China Dongfeng Motor Grp Co LTD Technol Ctr Wuhan 430058 Peoples R China

An efficient motion planning and control model for dynamic traffic environments is proposed to realise automated lane change of autonomous vehicles and meet the safety, comfort and real-time constraints. The nonlinear dynamics related to the road adhesion coefficient are considered in the constraints, and sequential quadratic programming (SQP) is used to solve the constrained optimisation problem. Central to the robustness of the SQP algorithm is the use of a non-monotone line search method and a merit function. Considering the nonlinear lateral and longitudinal dynamic coupling of the vehicle and the adhesion uncertainty, a trajectory tracking control based on model predictive control (MPC) is proposed to improve the accuracy and dynamic stability. The simulation results reveal that the lane change model can effectively prevent collisions with surrounding dynamic vehicles and complete lane change. Based on the SQP and MPC methods, the solution time is significantly shortened, which meets real-time and effective requirements.

关键词： motion planning trajectory tracking lane change road adhesion coefficient MPC model predictive control SQP sequential quadratic programming non-monotone line search

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Direct optimization using collocation based on high-order Gauss-Lobatto quadrature rules

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1996年第3期19卷 592-599页

作者： Herman, AL Conway, BA Illinois Univ. Urbana

The method of collocation and nonlinear programming has been used recently to solve a number of optimal control problems. In this method polynomials are commonly used to represent the state variable time histories over subintervals of the total time of interest. These polynomials correspond to a family of modified-Gaussian quadrature rules known as the Gauss-Lobatto rules. Presently, relatively low-order rules from the Gauss-Lobatto family, such as the trapezoid and Simpson's rule, are used to construct collocation solution schemes. In this work higher-order Gauss-Lobatto quadrature rules are formulated using collocation point selection based on a particular family of Jacobi polynomials. The advantage of using a quadrature rule of higher order is that the approximation using the higher degree polynomial may be more accurate, due to finite precision arithmetic, than a formulation based on a lower degree polynomial. In addition, the number of subintervals and, therefore, the number of nonlinear programming parameters needed to solve a problem accurately may he significantly reduced from that required if the conventional trapezoidal or Simpson's quadrature schemes are used, An optimal trajectory maximizing final energy for a low-thrust spacecraft is used to demonstrate the benefits of using the higher-order schemes.

关键词： Nonlinear programming Trajectory Optimization Numerical Integration Earth sequential quadratic programming Spacecraft Trajectories Computer Programs Runge Kutta Integration Boundary Value Problems Low Thrust Propulsion

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Synthesis and implementation aspects of linear antenna arrays with shaped radiation pattern for mobile communications

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IET MICROWAVES ANTENNAS & PROPAGATION 2016年第4期10卷 442-452页

作者： Schlosser, Edson R. Heckler, Marcos V. T. Machado, Renato Tinoco Salazar, Alexis Fabricio Univ Fed Pampa UNIPAMPA Campus Alegrete BR-97546550 Alegrete RS Brazil Univ Fed Santa Maria Dept Elect & Comp BR-97105900 Santa Maria RS Brazil Inst Tecnol Aeronaut Lab Antennas & Propagat BR-12228900 Sao Jose Dos Campos SP Brazil

This study presents a technique to design antenna arrays with shaped radiation pattern. The efficiency of the proposed technique is demonstrated for the optimisation of a linear microstrip array for radio base stations of mobile communication systems. The main beam is shaped so as to provide uniform distribution of power inside a sector of a cell and to minimise the power radiated above the horizon. The synthesis of the shaped pattern is achieved by a combination of genetic algorithm and sequential quadratic programming. In contrast to several papers found in the literature that consider only isotropic antennas, the proposed approach takes into account all the radiation properties of small arrays, such as the mutual coupling between the array elements and edge effects. Finally, the design of the feeding system to produce the synthesised pattern is discussed. Measurements are used to validate the proposed technique.

关键词： antenna radiation patterns linear antenna arrays genetic algorithms quadratic programming mobile communication linear antenna arrays shaped radiation pattern design antenna arrays optimisation linear microstrip array mobile communication systems uniform distribution genetic algorithm sequential quadratic programming isotropic antennas radiation properties mutual coupling edge effects feeding system

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