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Minimization of Cable-Net Reflector Shape Error by Machine Learning

JOURNAL OF SPACECRAFT AND ROCKETS 2019年第6期56卷 1757-1764页

作者： Tang, Yaqiong Li, Tuanjie Liu, Yang Wang, Zuowei Xidian Univ Sch Mechano Elect Engn POB 188 Xian 710071 Shaanxi Peoples R China

During assembly of a cable-net reflector, surface adjustments must be made to meet the stick accuracy requirement of a space mission by changing the lengths of adjustable cables. It is desirable to find the optimum adjustment amount based on the current state of the cable-net reflector. However, all data needed to establish an accurate simulation model for the cable-net reflector cannot be measured. Therefore, the cable-net reflector is treated as a black box, and a machine learning algorithm (support vector machine) is used to develop a prediction model to establish the relationship between cable length adjustments and surface accuracy. The k-fold cross-validation method is used to estimate the generalization error. The simulated annealing and grid search are combined to get the optimum hyperparameters for the prediction model. Next, a surface adjustment method is developed to calculate the optimal cable lengths. A tension truss reflector example is used to demonstrate the support vector machine prediction model and the adjustment method. The machine learning algorithm identified the relationships between cable lengths and surface accuracy. Both surface accuracy and tension uniformity can be improved by adjusting the boundary cables and tension ties with this method using only information from the front-side nodes.

关键词： Empirical Risk Minimization Trusses Black Box Annealing Space Missions Finite Element Modeling Virtual Prototyping Lagrange Multipliers sequential quadratic programming Neural Networks

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Improved optical tomography based on hybrid frequency-domain and time-domain radiative transfer model

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INFRARED PHYSICS & TECHNOLOGY 2020年 111卷 103484-103484页

作者： Zhao, Fang-Zhou Qi, Hong Liu, Shao-Bin Ren, Ya-Tao Harbin Inst Technol Sch Energy Sci & Engn 92 West Dazhi St Harbin 150001 Peoples R China Minist Ind & Informat Technol Key Lab Aerosp Thermophys Harbin 150001 Peoples R China

Based on the hybrid frequency-domain (FD) and time-domain (TD) radiative transfer equation (RTE), a novel reconstruction strategy is developed to retrieve the optical parameter fields in the participating medium. The discrete ordinate method is employed to solve the forward FD and TD RTE to simulate the radiative transfer process. The sequential quadratic programming is utilized to solve the inverse problem for obtaining the optical parameters combined with an adjoint method. The Otsu algorithm is applied to the FD reconstructed results to distinguish the target region and the background region. To overcome the ill-posedness of the inverse problem, the generalized Gaussian Markov random field model is employed as the regularization term in the objective function. Various numerical experiments are studied and all results demonstrate that the proposed hybrid reconstruction scheme is suitable for efficient and accurate optical tomography by combining the FD and TD radiative transfer models. Meanwhile, the crosstalk of the ill-posed inverse problem can be alleviated effectively.

关键词： Optical tomography Otsu algorithm sequential quadratic programming Frequency-domain and time-domain Radiative transfer equation

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Ensemble strategy using particle swarm optimisation variant and enhanced local search capability

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SWARM AND EVOLUTIONARY COMPUTATION 2024年 84卷

作者： Hong, Libin Wang, Guodong Ozcan, Ender Woodward, John Hangzhou Normal Univ Sch Informat Sci & Technol 2318 Yuhangtang Rd Hangzhou Peoples R China Univ Nottingham Sch Comp Sci Wollaton Rd Nottingham NG8 1BB England Loughborough Univ Dept Comp Sci Epinal Way Loughborough LE11 3TU England

Particle swarm optimisation is a population-based algorithm for evolutionary computation. A notable recent research direction has been to combine different effective mechanisms to enhance both exploration and exploitation capabilities while employing suitable mechanisms at appropriate instances in the evolutionary process. This study entailed the development of an ensemble strategy that uses a variant of the modified particle swarm optimisation algorithm with a covariance matrix adapted to the retreat phase and sequential quadratic programming. The modified particle swarm optimisation algorithm employs nonlinear population size reduction and uses the candidate elite best solution as the stochastic learning strategy and the fitness -distance balance as the terminal updating mechanism. The proposed algorithm was compared with the most recently proposed particle swarm optimisation-based variants through testing on CEC2017 benchmark functions. In the experimental results, the proposed method achieved the best ranking and exhibited excellent performance. Further effectiveness tests demonstrated that the proposed combination of algorithms and mechanisms exhibits tacit cooperation and significantly improves performance.

关键词： Ensemble strategy Particle swarm optimisation Covariance matrix adapted retreat sequential quadratic programming Fitness-distance balance

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Design and control of libration point spacecraft formations

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2007年第4期30卷 899-909页

作者： Infeld, Samantha I. Josselyn, Scott B. Murray, Walter Ross, I. Michael Stanford Univ Stanford CA 94305 USA USN Postgrad Sch Monterey CA 93943 USA

We investigate the concurrent problem of orbit design and formation control around a libration point. Concurrency implies that the design and control problem are simultaneously investigated. Separating the two problems is both unnecessary and ill-advised. The full problem can be naturally cast as a multi-agent, nonlinear, constrained optimal control problem. The optimality criterion is fuel consumption because the engineering feasibility of a formation design is dominated by the amount of propellant required to maintain a formation. Contrary to popular belief, quadratic costs do not measure fuel consumption;consequently, we take a direct measure of fuel consumption given by the L-t norm of the control acceleration. Fuel budgets to individual spacecraft are allocated by isoperimetric constraints. As with most nonlinear problems, the resulting problem does not have closed-form solutions. The full problem is solved by a Legendre pseudospectral method implemented in DIDO. DIDO exploits SNOPT, an active-set sequential quadratic programming solver, and generates quick solutions to facilitate redesign, an important requirement during the early stages of formation design. This approach does not use linearizations in modeling the dynamics, nor does it require analytical results;rather, the inherent nonlinearities associated with the problem are automatically exploited. Furthermore, we take advantage of a true distributed system architecture that does not rely on designing a leader-follower system. Sample results for formations about the sun-Earth and Earth-moon L2 point in the three-body circular restricted dynamical framework are presented. Optimal solutions for relaxed and almost periodic formations are presented for both a large separation constraint (about a third to half of orbit size), and a small separation constraint (about a millionth of orbit size).

关键词： Astronomical Unit Spacecraft Formation Covector Mapping Principle Earth Propellant Fuel Consumption sequential quadratic programming Legendre Pseudospectral Method Orbital Elements MATLAB

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Robust Optimization of Nanometer SRAM Designs

Robust Optimization of Nanometer SRAM Designs

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作者： Dayal, Akshit Texas A&M University

Technology scaling has been the most obvious choice of designers and chip manufacturing companies to improve the performance of analog and digital circuits. With the ever shrinking technological node, process variations can no longer be ignored and play a significant role in determining the performance of nanoscaled devices. By choosing a worst case design methodology, circuit designers have been very munificent with the design parameters chosen, often manifesting in pessimistic designs with significant area overheads. Significant work has been done in estimating the impact of intra-die process variations on circuit performance, pertinently, noise margin and standby leakage power, for fixed transistor channel dimensions. However, for an optimal, high yield, SRAM cell design, it is absolutely imperative to analyze the impact of process variations at every design point, especially, since the distribution of process variations is a statistically varying parameter and has an inverse correlation with the area of the MOS transistor. Furthermore, the first order analytical models used for optimization of SRAM memories are not as accurate and the impact of voltage and its inclusion as an input, along with other design parameters, is often ignored. In this thesis, the performance parameters of a nano-scaled 6-T SRAM cell are modeled as an accurate, yield aware, empirical polynomial predictor, in the presence of intra-die process variations. The estimated empirical models are used in a constrained non-linear, robust optimization framework to design an SRAM cell, for a 45 nm CMOS technology, having optimal performance, according to bounds specified for the circuit performance parameters, with the objective of minimizing on-chip area. This statistically aware technique provides a more realistic design methodology to study the trade off between performance parameters of the SRAM. Furthermore, a dual optimization approach is followed by considering SRAM power supply and wordline

关键词： SRAM Static Noise Margin Leakage Power Response Surface Modeling Dynamic noise Margin Non Linear programming Access Time sequential quadratic programming Book Thesis

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Optimizing battery discharge management of PMSM vehicles using adaptive nonlinear predictive control and a Generalized Integrator

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AIN SHAMS ENGINEERING JOURNAL 2024年第12期15卷

作者： Ismail, Moustafa Magdi Al-Dhaifallah, Mujahed Rezk, Hegazy Habib, Habib Ur Rahman Hamad, Samir A. King Fahd Univ Petr & Minerals Interdisciplinary Res Ctr Sustainable Energy Syst Dhahran 31261 Saudi Arabia Minia Univ Fac Engn Elect Engn Dept EL Minya 61517 Egypt King Fahd Univ Petr & Minerals Control & Instrumentat Engn Dept Dhahran 31261 Saudi Arabia Prince Sattam Bin Abdulaziz Univ Coll Engn Wadi Alddawasir Dept Elect Engn Al Kharj Saudi Arabia Univ Engn & Technol Taxila Fac Elect & Elect Engn Dept Elect Engn Taxila 47050 Pakistan Beni Suef Univ Fac Technol & Educ Dept Proc Control Technol Bani Suwayf Egypt

Electric vehicles (EVs) are key to a sustainable future, but extending battery life is essential to reduce costs and environmental impact. Thus, this paper presents the development of an Adaptive Nonlinear Predictive Model (ANLPM), integrated with a Third Order Generalized Integrator (TOGI) flux observer, which enhances induced torque estimation and stator reactance in Permanent Magnet Synchronous Motor (PMSM) systems. The model employs a sequential quadratic programming (SQP) algorithm, ensuring numerical stability and efficiency within the Model Predictive Control (MPC) framework to handle nonlinear constraints effectively. Moreover, simulation results demonstrate that the ANLPM significantly outperforms classical Adaptive Linear Predictive Models (ALPM), Seven-Dimensional LPM (SDLPM), and Proportional-Integral (PI) control strategies. It achieves marked reductions in battery discharge current and energy consumption rates. Therefore, simulation comparisons, across different scenarios, show that ANLPM reduces battery discharge current by 3% over ALPM and 44.7% over PI, while cutting energy consumption by 12.2% and 28.2%, and decreasing parallel battery cells by 14.2% and 28%, respectively. Under high temperatures, ANLPM cuts battery consumption by 45.3% and reduces cells by 43.7% compared to SDLPM, highlighting its efficiency in managing energy and extending battery life in EVs.

关键词： ANLPM Adaptive Nonlinear Predictive Model ALPM Adaptive Linear Predictive Models DC Direct Current DP Dynamic programming EVs Electric Vehicles FEM Finite Element Method MPC Model Predictive Control MTPA Maximum Torque per Ampere PMSM Permanent Magnet Synchronous Motor PI Proportional Integral PWM Pulse Width Modulation QP quadratic programming RL Reinforcement Learning SQP sequential quadratic programming SSE Steady State Error SDALPM Seven-dimensional adaptive linear predictive model TOGI Third Order Generalized Integrator VSI Voltage Source Inverter

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Optimization of shielded metal arc weld metal composition for charpy toughness

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WELDING JOURNAL 2004年第10期83卷 267S-276S页

作者： Murugananth, M Babu, SS David, SA Oak Ridge Natl Lab Div Met & Ceram Oak Ridge TN USA

Artificial neural network models that predict the Charpy-impact toughness values as a function of composition, heat treatment, and shielded metal arc welding process parameters were coupled with multipurpose optimization software. This coupled model was used to optimize the carbon, nickel, and manganese concentrations in a weld to achieve a maximum toughness of 120 J at -60degreesC. The coupled model used linear and nonlinear techniques to explore the possible combinations of carbon, manganese, and nickel concentrations for a given set of welding process parameters. An optimum weld metal composition was achieved only with nonlinear methods. The number of iterations and the exploration of input parameter space varied depending upon the type of nonlinear technique. The predicted weld metal composition was in agreement with published results.

关键词： Consumable Design Downhill Simplex Methods Genetic Algorithms Neural Network Modeling Nonlinear programming Optimization Methodologies sequential quadratic programming

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VIBRATION ISOLATION OF EXHAUST PIPE UNDER VEHICLE CHASSIS

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INTERNATIONAL JOURNAL OF VEHICLE DESIGN 1994年第1-2期15卷 131-142页

作者： LING, SF PAN, TC LIM, GH TSENG, CH Nanyang Technological Univ Singapore

The comfort of passengers is greatly affected by the characteristic vibrations transmitted from the exhaust pipe system to the vehicle body structure. Beam element is used to model the structural properties of the exhaust pipe. Rubber mountings, which link the exhaust pipe to the floor panel of the vehicle, are each characterized by a spring element with three translational and three rotational spring rates along their respective axes. sequential quadratic programming (SQP) and multi-objective optimization are employed to search for the optimal stiffnesses and the locations of the rubber mountings, to achieve minimum transmitted vibrational forces and moments. The results reveal that the rubber mounting locations followed by stiffnesses have considerable influence upon vibration isolation performance.

关键词： EXHAUST SYSTEM FINITE ELEMENT MODELING MULTIOBJECTIVE OPTIMIZATION sequential quadratic programming VIBRATION ISOLATION

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Electro-magnetohydrodynamic impact on Darrcy-Forchheimer viscous fluid flow over a stretchable surface: Integrated intelligent Neuro-evolutionary computing approach

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INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER 2022年 137卷

作者： Butt, Zeeshan Ikram Ahmad, Iftikhar Shoaib, Muhammad Ilyas, Hira Raja, Muhammad Asif Zahoor Univ Gujrat Dept Math Gujrat 50700 Pakistan COMSATS Univ Islamabad Dept Math Attock Campus Attock 43600 Pakistan Natl Yunlin Univ Sci & Technol Future Technol Res Ctr 123 Univ Rd Sect 3 Yunlin 64002 Taiwan

In this research-based study, the electro-magneto impacts are numerically observed during Darcy-Forchheimer (DF) viscous fluid flow having nonlinear form of thermal radiation. This two-dimensional fluid flow over a stretchable sheet is exposed to joule heating, thermal convection and viscous dissipation. The entire computa-tional work is successfully performed using reliable neuro computing technique (NCT) through a viable com-bination of genetic algorithms (GAs) a well-known global solver and a famous local solver named sequential quadratic programming (SQP) i-e NCT-GA-SQP. Partial differential equations (PDEs) that express the DF viscous fluid flow are successfully converted into a third order nonlinear system of ordinary differential equations (ODEs) through manipulation of similarity variables. Numerical illustrations with strong accuracy and effective graphical representations are adopted to visualize the velocity profile, thermal distribution and concentration of fluid flow due to the variational effects of various physical parameters namely the electric field parameter (E), magnetic parameter (M), the porosity parameter (lambda), the radiation parameter (Rd), the Prandtl number (Pr), the chemical reaction parameter (gamma) and the Schmidt number (Sc). The reference solutions attained through well-known Adams method are used to validate the numerical results gathered through complexity analysis and different statistical operators and are closely matched which guarantees the reliability of the proposed solver.

关键词： Darcy-Forchheimer Fluidic system Thermal radiation sequential quadratic programming

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Optimization of a Morphing Wing Based on Coupled Aerodynamic and Structural Constraints

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AIAA JOURNAL 2009年第9期47卷 2087-2104页

作者： Gamboa, P. Vale, J. Lau, F. J. P. Suleman, A. Univ Beira Interior Aerosp Sci Dept P-6200358 Covilha Portugal Inst Super Tecn Dept Mech Engn P-1049001 Lisbon Portugal Univ Victoria Dept Mech Engn Victoria BC V8W EP6 Canada

This paper presents the work done in designing a morphing wing concept for a small experimental unmanned aerial vehicle to improve the vehicle's performance over its intended speed range. The wing is designed with a multidisciplinary design optimization tool, in which an aerodynamic shape optimization code coupled with a structural morphing model is used to obtain a set of optimal wing shapes for minimum drag at different flight speeds. The optimization procedure is described as well as the structural model. The aerodynamic shape optimization code, that uses a viscous two-dimensional panel method formulation coupled with a nonlinear lifting-line algorithm and a sequential quadratic programming optimization algorithm, is suitable for preliminary wing design optimization tasks. The morphing concept, based on changes in wing-planform shape and wing-section shape achieved by extending spars and telescopic ribs, is explained in detail. Comparisons between optimized fixed wing performance, optimal morphing wing performance, and the performance of the wing obtained from the coupled aerodynamic-structural solution are presented. Estimates for the performance enhancements achieved by the unmanned aerial vehicles when fitted with this new morphing wing are also presented. Some conclusions on this concept are addressed with comments on the benefits and drawbacks of the morphing mechanism design.

关键词： Lift to Drag Ratio Aerodynamic Shape Optimization Micro Air Vehicle Airfoil Morphing Mechanisms High Aspect Ratio sequential quadratic programming Structural Modeling Multidisciplinary Design Optimization Aerodynamic Efficiency Airfoil Geometry

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