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An adaptive moment estimation framework for well placement optimization

COMPUTATIONAL GEOSCIENCES 2022年第4期26卷 957-973页

作者： Arouri, Yazan Sayyafzadeh, Mohammad Univ Adelaide Australian Sch Petr & Energy Resources Adelaide SA 5005 Australia

In this study, we propose the use of a first-order gradient framework, the adaptive moment estimation (Adam), in conjunction with a stochastic gradient approximation, to well location and trajectory optimization problems. The Adam framework allows the incorporation of additional information from previous gradients to calculate variable-specific progression steps. As a result, this assists the search progression to be adjusted further for each variable and allows a convergence speed-up in problems where the gradients need to be approximated. We argue that under computational budget constraints, local optimization algorithms provide suitable solutions from a heuristic initial guess. Nonlinear constraints are taken into account to ensure the proposed solutions are not in violation of practical field considerations. The performance of the proposed algorithm is compared against steepest descent and generalized pattern search, using two case studies - the placement of four vertical wells and placement of 20 nonconventional (deviated, horizontal and/or slanted) wells. The results indicate that the proposed algorithm consistently outperforms the tested methods in terms computational efficiency and final optimum value. Additional discussions regarding nonconventional parameterization provide insights into simultaneous perturbation gradient approximations.

关键词： Well placement gradient-based algorithm Adaptive moment estimation Field development optimization

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Numerical Solution of Fractional Optimal Control

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JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS 2019年第2期180卷 556-573页

作者： Li, Wen Wang, Song Rehbock, Volker Curtin Univ Dept Math & Stat GPO Box U1987 Perth WA 6845 Australia

This paper presents a numerical algorithm for solving a class of nonlinear optimal control problems subject to a system of fractional differential equations. We first propose a robust second-order numerical integration scheme for the system. The objective is approximated by the trapezoidal rule. We then apply a gradient-based optimization method to the discretized problem. Formulas for calculating the gradients are derived. Computational results demonstrate that our method is able to generate accurate numerical approximations for problems with multiple states and controls. It is also robust with respect to the fractional orders of derivatives.

关键词： Fractional nonlinear optimal control Numerical solution of fractional ODEs gradient-based algorithm gradient formula

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Experimental insights into consolidation rates during one-dimensional loading with special reference to excess pore water pressure

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ACTA GEOTECHNICA 2020年第12期15卷 3571-3591页

作者： Olek, Bartlomiej Szczepan Cracow Univ Technol Fac Civil Engn Ul Warszawska 24 PL-31155 Krakow Poland

Consolidation rate has significant influence on the settlement of structures founded on soft fine-grained soil. This paper presents the results of a series of small-scale and large-scale Rowe cell consolidation tests with pore water pressure measurements to investigate the factors affecting the consolidation process. Permeability and creep/resistance structure factors were considered as the governing factors. Intact and reconstituted marine clay from the Polish Carpathian Foredeep basin as well as clay-sand mixtures was examined in the present study. The fundamental relationship correlating consolidation degrees based on compression and pore water pressure was assessed to indicate the nonlinear soil behaviour. It was observed that the instantaneous consolidation parameters vary as the process progresses. The instantaneous coefficient of consolidation first drastically increases or decreases with increase in the degree of consolidation and stabilises in the middle stage of the consolidation;it then decreases significantly due to viscoplastic effects occurring in the soil structure. based on the characteristics of the relationship between coefficient of consolidation and degree of dissipation at the base, the consolidation range that complies with theoretical assumptions was established. Furthermore, the influence of coarser fraction in clay-sand mixtures in controlling the consolidation rates is discussed.

关键词： Clays Consolidation Data optimisation Excess pore water dissipation gradient-based algorithm Permeability

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A Hybrid Optimization Method OWGWA for EEG/ERP Adaptive Noise Canceller With Controlled Search Space

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INTERNATIONAL JOURNAL OF SWARM INTELLIGENCE RESEARCH 2020年第3期11卷 30-48页

作者： Nagal, Rachana Kumar, Pradeep Bansal, Poonam Amity Univ Noida India Maharaja Surajmal Inst Technol Delhi India

In this paper, a system for filtering event-related potentials/electroencephalograph is exhibited by adaptive noise canceller through an optimization algorithm, oppositional hybrid whale-grey wolf optimization algorithm (OWGWA). The OWGWA can choose the control parameters of the grey wolf algorithm utilizing whale parameters. To balance out the randomness of optimization strategies another methodology is implemented called controlled search space. Adaptive filter's noise reduction capability has been tested through adding adaptive white Gaussian noise over contaminated EEG signals at different noise levels. The performance of the proposed OWGWA-CSS algorithm is evaluated by signal to noise ratio in dB, mean value, and the relationship between resultant and input ERP. In this work, ANCs are also implemented by utilizing other optimization techniques. In average cases of noisy environment, comparative analysis shows that the proposed OWGWA-CSS technique provides higher SNR value, significantly lower mean and higher correlation as compared to other techniques.

关键词： Adaptive Noise Canceller Controlled Search Space EEG/ERP Signal Genetic algorithm gradient-based algorithm Oppositional based Learning Optimization algorithm Swarm-based algorithm

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Veco-Taxis as a Novel Engineered algorithm for Odor Source Localization

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INTERNATIONAL JOURNAL OF AMBIENT COMPUTING AND INTELLIGENCE 2020年第2期11卷 1-29页

作者： Gaurav, Kumar Kumar, Ajay Dayal, Ram Manipal Univ Jaipur Dept Mechatron Engn Jaipur Rajasthan India Manipal Univ Jaipur Acad Addit Responsibil Jaipur Rajasthan India Malaviya Natl Inst Technol Jaipur Jaipur Rajasthan India

algorithms with limited intelligence are unable to localize an odor source in an indoor environment with weak or no airflow. Stage wise solutions to odor source localization has been provided with a novel engineered algorithm called veco-taxis for plume traversal. It finds turn angles by calculating concentration gradients using vector algebra-based search algorithms. Levy walk is used in the plume finding phase. The concept of last chemical detection points (LCDPs) has been adopted for source declaration. The success rate of implemented algorithms is quantified using minimum and maximum move lengths-a key parameter-during source localization. A unified success and performance index (SPI) of the search algorithm is presented for the first time. SPI uncovers implicit parameters accountable for success in locating source and considers a qualitative performance. Higher SPIs are observed when the move length in plume finding is minimum and kept smaller than the plume traversal move length by some factor. It has been also demonstrated through simulations that veco-taxis is superior to the E. coli algorithm.

关键词： Chemical Plume Tracing Chemotaxis gradient-based algorithm Indoor Environment Levy Walk Mobile Robot Move Lengths Success and Performance Index

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Subpixel Matching Using Double-Precision gradient-based Method for Digital Image Correlation

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SENSORS 2021年第9期21卷 3140-3140页

作者： Liu, Gang Li, Mengzhu Zhang, Weiqing Gu, Jiawei Chongqing Univ Sch Civil Engn 83 Shabei St Chongqing 400045 Peoples R China

Digital image correlation (DIC) for displacement and strain measurement has flourished in recent years. There are integer pixel and subpixel matching steps to extract displacement from a series of images in the DIC approach, and identification accuracy mainly depends on the latter step. A subpixel displacement matching method, named the double-precision gradient-based algorithm (DPG), is proposed in this study. After, the integer pixel displacement is identified using the coarse-fine search algorithm. In order to improve the accuracy and anti-noise capability in the subpixel extraction step, the traditional gradient-based method is used to analyze the data on the speckle patterns using the computer, and the influence of noise is considered. These two nearest integer pixels in one direction are both utilized as an interpolation center. Then, two subpixel displacements are extracted by the five-point bicubic spline interpolation algorithm using these two interpolation centers. A novel combination coefficient considering contaminated noises is presented to merge these two subpixel displacements to obtain the final identification displacement. Results from a simulated speckle pattern and a painted beam bending test show that the accuracy of the proposed method can be improved by four times that of the traditional gradient-based method that reaches the same high accuracy as the Newton-Raphson method. The accuracy of the proposed method efficiently reaches at 92.67%, higher than the Newton-Raphon method, and it has better anti-noise performance and stability.

关键词： displacement measurement digital image correlation subpixel matching gradient-based algorithm linear combination

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Performance of sub-pixel registration algorithms in digital image correlation

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MEASUREMENT SCIENCE AND TECHNOLOGY 2006年第6期17卷 1615-1621页

作者： Pan, Bing Xie, Hui-min Xu, Bo-qin Dai, Fu-long Tsinghua Univ Dept Engn Mech Beijing 100084 Peoples R China Univ Sci & Technol China Dept Mech & Mech Engn Hefei 230027 Peoples R China

Developments in digital image correlation in the last two decades have made it a popular and effective tool for full-field displacement and strain measurements in experimental mechanics. In digital image correlation, the use of the sub-pixel registration algorithm is regarded as the key technique to improve accuracy. Different types of sub-pixel registration algorithms have been developed. However, little quantitative research has been carried out to compare their performances. This paper investigates three types of the most commonly used sub-pixel displacement registration algorithms in terms of the registration accuracy and the computational efficiency using computer-simulated speckle images. A detailed examination of the performances of each algorithm reveals that the iterative spatial domain cross-correlation algorithm (Newton-Raphson method) is more accurate, but much slower than other algorithms, and is recommended for use in these applications.

关键词： digital image correlation sub-pixel curve-fitting gradient-based algorithm Newton-Raphson method

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Comparison Between Analytic Derivative and the Technique of Differential Contributions in Reflectarray Phase-Only Synthesis 13

Comparison Between Analytic Derivative and the Technique of ...

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13th European Conference on Antennas and Propagation (EuCAP)

作者： Prado, Daniel R. Arrebola, Manuel Pino, Marcos R. Goussetis, George Heriot Watt Univ Inst Sensors Signals & Syst Edinburgh Midlothian Scotland Univ Oviedo Grp Signal Theory & Commun Oviedo Spain

ISBN: (纸本)9788890701887

Many algorithms for the optimization of array antennas need the calculation of a gradient to minimize a cost function. Usually, the best approach is to compute analytically the derivatives, since that way computations are faster. However, sometimes the derivatives are cumbersome to obtain or they cannot be calculated, such as when directly optimizing the layout in reflectarrays for cross-polarization improvement. In those cases, derivatives are evaluated using numerical techniques such as finite differences. In this work, we present the numerical technique of differential contributions (DFC) to accelerate gradient-based algorithms when the derivatives are calculated with finite differences, achieving a complexity time scaling of the same order as the analytical derivatives. The technique is applied to a far field phase-only synthesis for reflectarray antennas using the generalized Intersection Approach, and it is compared with the analytic derivatives and the use of finite differences with the FFT. The DFC technique shows superior performance in all cases, even than the analytic derivative.

关键词： gradient-based algorithm optimization synthesis reflectarray array far field differential contributions finite differences generalized Intersection Approach

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Data-Driven Feedforward Decoupling Filter Design for Parallel Nanopositioning Stages 9th

Data-Driven Feedforward Decoupling Filter Design for Paralle...

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9th International Conference on Intelligent Robotics and Applications (ICIRA)

作者： Feng, Zhao Ling, Jie Ming, Min Xiao, Xiaohui Wuhan Univ Sch Power & Mech Engn Wuhan 430072 Peoples R China

ISBN: (纸本)9783319435060;9783319435053

Cross-coupling effect severely hinder fast and accurate tracking for parallel piezo nanopositioning stages. In this paper, a data-driven feedforward decoupling filter (DDFDF) is proposed to reduce the cross-coupling caused errors. Traditional control methods for coupled system could achieve good performance on the premise that the dynamic model is accurate and no non-minimum phase zeros exist. The proposed method is totally data-driven with the advantage of no need for accurate identified model and model structure by Gauss-Newton gradient-based algorithm. The DDFDF for eliminating cross-coupling errors was verified on a 2-DOF coupled nanopositioning stage through simulations. Results show the effectiveness of the proposed controller by comparing with open-loop simulations and the well-designed feedback controller.

关键词： Parallel nanopositioning stage Cross-coupling effect Data-driven gradient-based algorithm

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WIND FARM LAYOUT OPTIMIZATION: A MULTI-STAGE APPROACH

WIND FARM LAYOUT OPTIMIZATION: A MULTI-STAGE APPROACH

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ASME International Mechanical Engineering Congress and Exposition (IMECE)

作者： Yang, Puyi Najafi, Hamidreza Florida Inst Technol Dept Mech & Civil Engn Melbourne FL 32901 USA

ISBN: (纸本)9780791885642

The Wind Farm Layout Optimization (WFLO) problem is a complex and non-convex optimization problem. Even though a lot of heuristic algorithms and mathematical programming methods have been tested and discussed, there is not a consensus about which algorithm is the most suitable one to solve the WFLO problems. Every algorithm has its own advantages and disadvantages on solving different problems, thus the multi-stage approaches have been picked up. One multi-stage approach applied in solving WFLO problems is to apply an algorithm in stage 1 to capture a coarse, initial optimized layout and import it to stage 2 as an initial condition for another algorithm for further refinement. This paper compared two types of multi-stage methods: The Heuristic-gradient-based (H-G) model which consists of a heuristic algorithm in stage 1 and a gradient-based algorithm in stage 2;The Discrete-Continuous (D-C) model which consists of a heuristic algorithm in discrete scheme in stage 1 and an algorithm in continuous scheme in stage 2. Annual Energy Production (AEP) is used as the objective function while the computational time associated with each approach is documented. The results illustrate most of the multistage models can improve the optimization procedure both in terms of AEP and computational time. Overall, it is found that the D-C approach is better than the H-G approach. Particularly, the combination of Greedy+Random Search provides the highest AEP and the combination of Greedy and SLSQP provides the lowest computational time.

关键词： Wind Farm Layout Optimization Multi-stage model Heuristic algorithm gradient-based algorithm

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