Efficient spreading strategy for global solution search using a trust-region optimization method: an application to CRS stacking problem

Geophysics ◽  
2021 ◽  
pp. 1-70
Author(s):  
Fedor Pisnitchenko ◽  
Momoe Sakamori
Keyword(s):  
Global Solution ◽  
Optimization Algorithm ◽  
Three Dimensional ◽  
Trust Region ◽  
Optimization Method ◽  
Computational Time ◽  
Parameter Search ◽  
Common Reflection Surface ◽  
Best Fitting ◽  
Local Optimization Method

Some processes in seismic imaging can be formulated as a coherence-based problem, such as common reflection surface (CRS) stacking.The approach consists of obtaining the CRS attributes that provide the best fitting CRS surface in the multi-coverage data. The problem can be described as an optimization problem and solved by an optimization algorithm. Generally, quick convergent optimization algorithms are local solvers. To obtain the global solution, an efficient strategy is proposed to be used combined with a trust-region local optimization method. This strategy can be divided into two features: sequential parameters search and spreading solution.The idea is to first find solutions on a coarse output grid by sequential parameter search. This feature is based on constructing splines to estimate the maxima of the objective function in one dimension. These estimated maxima are the initial approximations to the local solver.The optimization algorithm obtains the parameters by sequentially solving one, two, and three-dimensional problems. Once the solutions are found on the coarse grid, useful information is propagated in the neighborhood to obtain the solutions on all output grid. Although the idea of spreading solution seems easy, its implementation is complex. It is essential to consider the properties of the problem as well as the properties of the optimization algorithm. Through some numerical experiments, the results using this strategy are shown. The use of sequential parameter search and spreading solution provides an improvement not only in the parameters but also in computational time.

scholarly journals Optimal Eco-Driving Cycles for Conventional Vehicles Using a Genetic Algorithm

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4362
Author(s):  
Subramaniam Saravana Sankar ◽  
Yiqun Xia ◽  
Julaluk Carmai ◽  
Saiprasit Koetniyom
Keyword(s):  
Genetic Algorithm ◽  
Cost Function ◽  
Fuel Consumption ◽  
Optimization Algorithm ◽  
Internal Combustion Engines ◽  
Optimization Method ◽  
Computational Time ◽  
Weight Factor ◽  
Driving Cycles ◽  
The Cost

The goal of this work is to compute the eco-driving cycles for vehicles equipped with internal combustion engines by using a genetic algorithm (GA) with a focus on reducing energy consumption. The proposed GA-based optimization method uses an optimal control problem (OCP), which is framed considering both fuel consumption and driver comfort in the cost function formulation with the support of a tunable weight factor to enhance the overall performance of the algorithm. The results and functioning of the optimization algorithm are analyzed with several widely used standard driving cycles and a simulated real-world driving cycle. For the selected optimal weight factor, the simulation results show that an average reduction of eight percent in fuel consumption is achieved. The results of parallelization in computing the cost function indicates that the computational time required by the optimization algorithm is reduced based on the hardware used.

A Variational Art Algorithm for Image Generation

Leonardo ◽  
2016 ◽  
Vol 49 (3) ◽  
pp. 226-231
Author(s):  
Yoon Young Kim ◽  
Jae Chun Ryu ◽  
Eunil Kim ◽  
Hyoungkee Kim ◽  
Byungseong Ahn
Keyword(s):  
Topology Optimization ◽  
System Design ◽  
Optimization Algorithm ◽  
Three Dimensional ◽  
Optimization Method ◽  
Image Generation ◽  
System A ◽  
Path System ◽  
Virtual System ◽  
Topology Optimization Method

The authors propose a variational art algorithm: a virtual system-based optimization algorithm developed for generating images. Observing that the topology optimization method used for multiphysics system design can produce two- or three-dimensional layouts without baselines, the authors propose to expand it beyond engineering applications for generating images. They have devised a virtual physical system—a heat-path system—that “interprets” the optimization-based process of image generation as the simultaneous drawing of multiple strokes in a painting.

scholarly journals A particle-linkage model for elongated asteroids with three-dimensional mass distribution

2021 ◽  
Vol 502 (3) ◽  
pp. 4277-4289
Author(s):  
L B T Santos ◽  
L O Marchi ◽  
S Aljbaae ◽  
P A Sousa-Silva ◽  
D M Sanchez ◽  
...  
Keyword(s):  
Dimensional Space ◽  
Equilibrium Points ◽  
Three Dimensional ◽  
Optimization Method ◽  
Computational Time ◽  
Three Dimensional Model ◽  
Gravitational Fields ◽  
Proposed Model ◽  
Polyhedral Shape ◽  
Linkage Model

ABSTRACT The goal of this paper is to develop a simplified model to describe the gravitational fields of elongated asteroids. The proposed model consists of representing an elongated asteroid using a triple-particle-linkage system distributed in the three-dimensional space and it is an extension of previous planar models. A nonlinear optimization method is used to determine the parameters of our model, minimizing the errors of all the external equilibrium points with respect to the solutions calculated with a more realistic approach, the Mascon model, which are assumed to give the real values of the system. The model considered in this paper is then applied to three real irregular asteroids: 1620 Geographos, 433 Eros, and 243 Ida. The results show that the current triple-particle-linkage three-dimensional model gives better accuracy when compared to the axisymmetric triple-particle-linkage model available in the literature, and provides an advantage in terms of accuracy over the mass point model, while keeping computational time low. This model is also used to carry out simulations to characterize regions with solutions that remain bounded or that escape from around each asteroid under analysis. We investigated initial inclinations of 0° (direct orbits) and 180° (retrograde orbits). We considered the gravitational field of the asteroid, the gravitational attraction of the Sun, and the SRP. Our results are then compared to the results obtained using the Mascon gravitational model, based on the polyhedral shape source. We found good agreement between the two models.

scholarly journals An improved 3DMax algorithm to reconstruct the three-dimensional structure of the chromosome

2020 ◽  
Author(s):  
Liwei Liu ◽  
Huili Yao
Keyword(s):  
Objective Function ◽  
Optimization Algorithm ◽  
Optimization Problem ◽  
3D Structure ◽  
Three Dimensional ◽  
Optimization Method ◽  
Dimensional Structure ◽  
Chromosome Conformation ◽  
Three Dimensional Structure ◽  
Interaction Map

AbstractIn recent years, with the development of high-throughput chromosome conformation capture (Hi-C) technology and the reduction of high-throughput sequencing cost, the data volume of whole-genome interaction has increased rapidly, and the resolution of interaction map keeps improving. Great progress has been made in the research of 3D structure modeling of chromosomes and genomes. Several methods have been proposed to construct the chromosome structure from chromosome conformation capture data. Based on the Hi-C data, this paper analyses the relevant literature of chromosome 3D structure reconstruction and it summarizes the principle of 3DMAX, which is a classical algorithm to construct the 3D structure of a chromosome. In this paper, we introduce a new gradient ascent optimization algorithm called XNadam that is a variant of Nadam optimization method. When XNadam is applied to 3DMax algorithm, the performance of 3DMax algorithm can be improved, which can be used to predict the three-dimensional structure of a chromosome.Author summaryThe exploration of the three-dimensional structure of chromosomes has gradually become a necessary means to understand the relationship between genome function and gene regulation. An important problem in the construction of three-dimensional model is how to use the interaction map. Usually, the interaction frequency can be transformed into the spatial distance according to the deterministic or non-deterministic function relationship, and the interaction frequency can be weighted as weight in the objective function of the optimization problem. When the frequency of interaction is weighted as weight in the objective function of the optimization problem, what kind of optimization method is used to optimize the objective function is the problem we consider. In order to solve this problem, we provide an improved stochastic gradient ascent optimization algorithm(XNadam). The XNadam optimization algorithm combined with maximum likelihood algorithm is applied to high resolution Hi-C data set to infer 3D chromosome structure.

scholarly journals Discrete element simulation of the charge in the hopper of a blast furnace, calibrating the parameters through an optimization algorithm

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Gabriele Degrassi ◽  
Lucia Parussini ◽  
Marco Boscolo ◽  
Nicola Petronelli ◽  
Vincenzo Dimastromatteo
Keyword(s):  
Blast Furnace ◽  
Optimization Algorithm ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Discrete Element ◽  
Conveyor Belt ◽  
Computational Time ◽  
Engineering Software ◽  
Computer Aided ◽  
Proper Material

AbstractThe purpose of this study is to simulate the distribution of a coarse granular material discharged in a hopper via a conveyor belt. This simulation is intended to be a model calibration for an optimization that will be later performed to obtain a proper material distribution device. From the hopper, the material is discharged in a blast furnace. Hence, achieving an adequate distribution in the hopper is crucial, since that distribution is directly linked to how the material spreads in the blast furnace, and this heavily influences the efficiency of the whole steel-making process. The apparatus is modeled by online three dimensional Computer-Aided Design software Onshape. Rocky DEM, a Computer-Aided Engineering software based on Discrete Element Method, is used to simulate the charge. The parameters of the numerical model are calibrated through an optimization algorithm. This phase is realized thanks to the optimization platform modeFRONTIER, using an algorithm that exploits meta-models to reduce the computational time of the optimization. By comparing the simulated results with the visual data obtained from blast furnace plant, the goal is to validate the model and to better understand the behavior of the whole charging process.

scholarly journals A Proof-of-Concept Algorithm for the Retrieval of Total Column Amount of Trace Gases in a Multi-Dimensional Atmosphere

2021 ◽  
Vol 13 (2) ◽  
pp. 270
Author(s):  
Adrian Doicu ◽  
Dmitry S. Efremenko ◽  
Thomas Trautmann
Keyword(s):  
Trace Gases ◽  
Three Dimensional ◽  
Principal Component ◽  
Radiative Transfer Model ◽  
Computational Time ◽  
Transfer Model ◽  
Proof Of Concept ◽  
Discrete Ordinate ◽  
Distribution Method ◽  
Total Column

An algorithm for the retrieval of total column amount of trace gases in a multi-dimensional atmosphere is designed. The algorithm uses (i) certain differential radiance models with internal and external closures as inversion models, (ii) the iteratively regularized Gauss–Newton method as a regularization tool, and (iii) the spherical harmonics discrete ordinate method (SHDOM) as linearized radiative transfer model. For efficiency reasons, SHDOM is equipped with a spectral acceleration approach that combines the correlated k-distribution method with the principal component analysis. The algorithm is used to retrieve the total column amount of nitrogen for two- and three-dimensional cloudy scenes. Although for three-dimensional geometries, the computational time is high, the main concepts of the algorithm are correct and the retrieval results are accurate.

Research on the application of 3D reconstruction technology in traditional handicraft design

2021 ◽  
pp. 002072092110052
Author(s):  
GuoLong Zhang
Keyword(s):  
Poisson Equation ◽  
Optimization Algorithm ◽  
Three Dimensional ◽  
Reconstruction Algorithm ◽  
Social Production ◽  
Design Constraint ◽  
Reconstruction Process ◽  
Key Steps ◽  
Shielding Design ◽  
Reconstruction Model

The use of computer technology for three-dimensional (3 D) reconstruction is one of the important development directions of social production. The purpose is to find a new method that can be used in traditional handicraft design, and to explore the application of 3 D reconstruction technology in it. Based on the description and analysis of 3 D reconstruction technology, the 3 D reconstruction algorithm based on Poisson equation is analyzed, and the key steps and problems of the method are clarified. Then, by introducing the shielding design constraint, a 3 D reconstruction algorithm based on shielded Poisson equation is proposed. Finally, the performance of two algorithms is compared by reconstructing the 3 D image of rabbit. The results show that: when the depth value of the algorithm is 11, the surface of the rabbit image obtained by the proposed optimization algorithm is smoother, and the details are more delicate and fluent; under different depth values, with the increase of the depth value, the number of vertices and faces of the two algorithms increase, and the optimal depth values of 3 D reconstruction are more than 8. However, the proposed optimization algorithm has more vertices, and performs better in the reconstruction process; the larger the depth value is, the more time and memory are consumed in 3 D reconstruction, so it is necessary to select the appropriate depth value; the shielding parameters of the algorithm have a great impact on the fineness of the reconstruction model. The larger the parameter is, the higher the fineness is. In a word, the proposed 3 D reconstruction algorithm based on shielded Poisson equation has better practicability and superiority.

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

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