An Evaluation of the Semi-Coupled Scheme for the Analysis of Floating Production Systems

2014 ◽  
Author(s):  
Aldo Roberto Cruces Girón ◽  
Fabrício Nogueira Corrêa ◽  
Breno Pinheiro Jacob
Keyword(s):  
Deep Water ◽  
Production Systems ◽  
Computational Cost ◽  
The Other ◽  
Coupled Analysis ◽  
Computational Costs ◽  
Analysis Techniques ◽  
Early Design Stages ◽  
Accuracy Of Results ◽  
Low Computational Cost

Analysis techniques and numerical formulations are available in a variety for mooring and riser designers. They are applied in the different stages of the design processes of floating production systems (FPS) by taking advantage of both the accuracy of results and the computational costs. In early design stages, the low computational cost is more valued with the aim of obtaining fast results and taking decisions. So in these stages it is common to use uncoupled analysis. On the other hand, in more advanced design stages, the accuracy of results is more valued, for which the use of coupled analysis is adequate. However, it can lead to excessive computing times. To overcome such high computational costs, new formulations have been proposed with the aim of obtaining results similar to a coupled analysis, but with low computational costs. One of these formulations is referred as the semi-coupled scheme (S-C). Its main characteristic is that it combines the advantages of uncoupled and coupled analysis techniques. In this way, analyses can be performed with very fast execution times and results are superior to those obtained by the classical uncoupled analysis. This work presents an evaluation of the S-C scheme. The evaluation is made by comparing their results with the results of coupled analyses. Both type of analysis were applied in a representative deep water platform. The results show that the S-C scheme have the potentially to provide results with appropriate precision with very low computational times. In this way, the S-C scheme represents an attractive procedure to be applied in early and intermediate stages of the design process of FPS.

scholarly journals A New Generalized Projection and Its Application to Acceleration of Audio Declipping

Axioms ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 105
Author(s):  
Pavel Rajmic ◽  
Pavel Záviška ◽  
Vítězslav Veselý ◽  
Ondřej Mokrý
Keyword(s):  
Signal Processing ◽  
Convex Optimization ◽  
Linear Operator ◽  
Explicit Formula ◽  
Convex Sets ◽  
State Of The Art ◽  
Computational Cost ◽  
The Other ◽  
Speed Up ◽  
Low Computational Cost

In convex optimization, it is often inevitable to work with projectors onto convex sets composed with a linear operator. Such a need arises from both the theory and applications, with signal processing being a prominent and broad field where convex optimization has been used recently. In this article, a novel projector is presented, which generalizes previous results in that it admits to work with a broader family of linear transforms when compared with the state of the art but, on the other hand, it is limited to box-type convex sets in the transformed domain. The new projector is described by an explicit formula, which makes it simple to implement and requires a low computational cost. The projector is interpreted within the framework of the so-called proximal splitting theory. The convenience of the new projector is demonstrated on an example from signal processing, where it was possible to speed up the convergence of a signal declipping algorithm by a factor of more than two.

Semi-Coupled Scheme for the Analysis of Floating Production Systems

2013 ◽  
Author(s):  
Fabrício Nogueira Corrêa ◽  
Breno Pinheiro Jacob
Keyword(s):  
Dynamic Analysis ◽  
Production Systems ◽  
Equations Of Motion ◽  
Coupled Analysis ◽  
Design Practice ◽  
Load Case ◽  
Current Profile ◽  
Hydrodynamic Analysis ◽  
Computational Costs ◽  
Numerical Tools

Traditionally, the design practice of floating production systems (FPS) employed uncoupled numerical tools where firstly the hydrodynamic analysis of the hull is performed with the lines represented by scalar models (leading to the hull motions); subsequently, these motions are prescribed at Finite Element (FE) models of the lines. Nowadays, it is widely acknowledged that coupled analysis tools should be employed for deep-water applications, considering that the overall behavior is dictated by the interaction between the hydrodynamic behavior of the hull and the structural behavior of the lines. In this context, considering that in some situations the use of coupled formulations can lead to excessive computing times, this work presents a formulation for the analysis of FPS, referred here as the semi-coupled (S-C) strategy. Its goal is to attain faster simulations than a coupled formulation, with better accuracy than usually provided by the classical uncoupled scheme. In this strategy, for each load case a coupled static simulation is performed. From this simulation a global 6-DOF stiffness matrix that represents the array of lines is automatically calculated and added to the global matrix for the subsequent dynamic analysis to solve the equations of motion of the hull. Therefore, this dynamic analysis will adequately consider the nonlinear stiffness contribution of the lines, as well as the effect of the current profile acting on them, all evaluated at the static mean position for each load case. Case studies are presented to compare the computational costs and accuracy of this S-C strategy with coupled formulations.

Numerical Simulation of AA2024-T3 Friction Stir Welding (FSW) Process: Sensitivity Analyses and Influence of Decisions during Modelling Stages

2015 ◽  
Vol 651-653 ◽  
pp. 919-924 ◽  
Author(s):  
Rui M.F. Paulo ◽  
Pierpaolo Carlone ◽  
Robertt A.F. Valente ◽  
Filipe Teixeira-Dias ◽  
Gaetano S. Palazzo
Keyword(s):  
Friction Stir Welding ◽  
Good Accuracy ◽  
Computational Cost ◽  
The Other ◽  
Sensitivity Analyses ◽  
Element Analysis ◽  
Shell Elements ◽  
Friction Stir ◽  
The One ◽  
Low Computational Cost

The main objective of the present work is to assess the influence of several parameters relevant for Finite Element Analysis (FEA) in modelling Friction Stir Welding (FSW) processes on AA2024-T3 plates. Several tests were performed including variations on the type of shell elements, number of integration points across thickness direction and mesh refinement levels, aiming for good accuracy and low computational cost. On the one hand, several setups of the mechanical boundary conditions, modelling the clamping systems, were also tested, leading to the conclusion that the results, in terms of longitudinal residual stresses, are significantly affected by this factor. On the other hand, variations on the heat input distribution showed a reduced effect, or almost null, on the final results.

Evaluation of Safe and Failure Zones of Risers and Mooring Lines of Floating Production Systems

2013 ◽  
Author(s):  
Aldo Roberto Cruces Girón ◽  
Fabrício Nogueira Corrêa ◽  
Breno Pinheiro Jacob
Keyword(s):  
Deep Water ◽  
Production Systems ◽  
Early Stage ◽  
Coupled System ◽  
The Other ◽  
Mooring System ◽  
Mooring Lines ◽  
Global Response ◽  
Design Procedures ◽  
Safe Operating

In recent years, the design procedures of risers and mooring system for floating production systems (FPS) have had more feedback. In this way mooring and risers designers can identify, even in an early stage, the constraints imposed by one system over the other. This work presents an evaluation of the crossing of the information obtained from the analyses of risers and mooring system. Different riser and mooring analysis procedures are applied to a typical FPS for deep water applications. First, failure zones of the riser system are identified, so a safe operating limit zone can be defined. Then, the excursions of the platform are calculated taking into account the global response of the coupled system (hull, mooring lines and risers). Finally, the results are crossed in order to verify if the excursions of the platform are within the safe operating area. The evaluation presented here shows the important of correctly defining the safe operational zones and how the crossing of information can be conservative or not within the design process of mooring lines and risers.

Competitive Learning with Fast Neuron-Insertion

2005 ◽  
Vol 9 (6) ◽  
pp. 590-598 ◽  
Author(s):  
Noritaka Shigei ◽  
◽  
Hiromi Miyajima ◽  
Michiharu Maeda ◽  
Keyword(s):  
Image Compression ◽  
Vector Quantization ◽  
Computational Cost ◽  
Competitive Learning ◽  
The Other ◽  
Computational Costs ◽  
Adaptive Vector Quantization ◽  
Small Set ◽  
Insertion Techniques ◽  
Conventional Methods

Adaptive Vector Quantization (AVQ) is to find a small set of weight vectors that well approximates a larger set of input vectors. This paper presents a fast AVQ method Competitive Learning with Approximate Neuron-Insertion (CLANI). Though neuron-insertion techniques can much enhance the accuracy in AVQ, a naive implementation requires a large computational cost proportional to the number of input vectors. Approximate neuron-insertion has an advantage that its computational cost is independent of the number of input vectors. We theoretically estimate the computational costs of CLANI and the other conventional methods. The effectiveness of CLANI is demonstrated in vector quantization simulations and an image compression application.

scholarly journals A mesoscopic simulator to uncover heterogeneity and evolutionary dynamics in tumors

2020 ◽  
Author(s):  
Jiménez-Sánchez Juan ◽  
Martínez-Rubio Álvaro ◽  
Popov Anton ◽  
Pérez-Beteta Julián ◽  
Azimzade Youness ◽  
...  
Keyword(s):  
Tumor Heterogeneity ◽  
Evolutionary Dynamics ◽  
Computational Cost ◽  
Imaging Data ◽  
Mesoscopic Simulation ◽  
Computational Costs ◽  
Cellular Processes ◽  
Physical Scale ◽  
Spatio Temporal ◽  
Low Computational Cost

AbstractIncreasingly complex in-silico modeling approaches offer a way to simultaneously access cancerous processes at different spatio-temporal scales. High-level models, such as those based on partial differential equations, are computationally affordable and allow large tumor sizes and long temporal windows to be studied, but miss the discrete nature of many key underlying cellular processes. Individual-based approaches provide a much more detailed description of tumors, but have difficulties when trying to handle full-sized real cancers. Thus, there exists a trade-off between the integration of macroscopic and microscopic information, now widely available, and the ability to attain clinical tumor sizes. In this paper we put forward a stochastic mesoscopic simulation framework that incorporates key cellular processes during tumor progression while keeping computational costs to a minimum. Our framework captures a physical scale that allows both the incorporation of microscopic information, tracking the spatio-temporal emergence of tumor heterogeneity and the underlying evolutionary dynamics, and the reconstruction of clinically sized tumors from high-resolution medical imaging data, with the additional benefit of low computational cost. We illustrate the functionality of our modeling approach for the case of glioblastoma, a paradigm of tumor heterogeneity that remains extremely challenging in the clinical setting.Author summaryComputer simulation based on mathematical models provides a way to improve the understanding of complex processes in oncology. In this paper we develop a stochastic mesoscopic simulation approach that incorporates key cellular processes while keeping computational costs to a minimum. Our methodology captures the development of tumor heterogeneity and the underlying evolutionary dynamics. The physical scale considered allows microscopic information to be included, tracking the spatio-temporal evolution of tumor heterogeneity and reconstructing clinically sized tumors from high-resolution medical imaging data, with a low computational cost. We illustrate the functionality of the modeling approach for the case of glioblastoma, an epitome of heterogeneity in tumors.

scholarly journals A Method to Compensate for the Errors Caused by Temperature in Structured-Light 3D Cameras

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2073
Author(s):  
Oriol Vila ◽  
Imma Boada ◽  
David Raba ◽  
Esteve Farres
Keyword(s):  
Low Cost ◽  
Computational Cost ◽  
Depth Map ◽  
Industrial Applications ◽  
The Other ◽  
Effect Of Temperature ◽  
Step Method ◽  
Hyperbolic Paraboloid ◽  
Thermal Chamber ◽  
Low Computational Cost

Although low cost red-green-blue-depth (RGB-D) cameras are factory calibrated, to meet the accuracy requirements needed in many industrial applications proper calibration strategies have to be applied. Generally, these strategies do not consider the effect of temperature on the camera measurements. The aim of this paper is to evaluate this effect considering an Orbbec Astra camera. To analyze this camera performance, an experimental study in a thermal chamber has been carried out. From this experiment, it has been seen that produced errors can be modeled as an hyperbolic paraboloid function. To compensate for this error, a two-step method that first computes the error and then corrects it has been proposed. To compute the error two possible strategies are proposed, one based on the infrared distortion map and the other on the depth map. The proposed method has been tested in an experimental scenario with different Orbbec Astra cameras and also in a real environment. In both cases, its good performance has been demonstrated. In addition, the method has been compared with the Kinect v1 achieving similar results. Therefore, the proposed method corrects the error due to temperature, is simple, requires a low computational cost and might be applicable to other similar cameras.

scholarly journals Low-Computational-Cost Technique for Modeling Macro Fiber Composite Piezoelectric Actuators Using Finite Element Method

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4316
Author(s):  
Diaa Emad ◽  
Mohamed A. Fanni ◽  
Abdelfatah M. Mohamed ◽  
Shigeo Yoshida
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fiber Composite ◽  
Computational Cost ◽  
Computational Time ◽  
Detailed Model ◽  
Computational Costs ◽  
Macro Fiber Composite ◽  
Low Computational Cost ◽  
Element Method

The large number of interdigitated electrodes (IDEs) in a macro fiber composite (MFC) piezoelectric actuator dictates using a very fine finite element (FE) mesh that requires extremely large computational costs, especially with a large number of actuators. The situation becomes infeasible if repeated finite element simulations are required, as in control tasks. In this paper, an efficient technique is proposed for modeling MFC using a finite element method. The proposed technique replaces the MFC actuator with an equivalent simple monolithic piezoceramic actuator using two electrodes only, which dramatically reduces the computational costs. The proposed technique was proven theoretically since it generates the same electric field, strain, and displacement as the physical MFC. Then, it was validated with the detailed FE model using the actual number of IDEs, as well as with experimental tests using triaxial rosette strain gauges. The computational costs for the simplified model compared with the detailed model were dramatically reduced by about 74% for memory usage, 99% for result file size, and 98.6% for computational time. Furthermore, the experimental results successfully verified the proposed technique with good consistency. To show the effectiveness of the proposed technique, it was used to simulate a morphing wing covered almost entirely by MFCs with low computational cost.

The Influence of Water Regime on the Performance of Aquatic Plants

1994 ◽  
Vol 29 (4) ◽  
pp. 127-132 ◽  
Author(s):  
Naomi Rea ◽  
George G. Ganf
Keyword(s):  
Deep Water ◽  
Aquatic Plants ◽  
Water Regime ◽  
Optimal Performance ◽  
Experimental Results ◽  
The Other ◽  
Full Potential ◽  
Influence Of Water ◽  
Emergent Species

Experimental results demonstrate bow small differences in depth and water regime have a significant affect on the accumulation and allocation of nutrients and biomass. Because the performance of aquatic plants depends on these factors, an understanding of their influence is essential to ensure that systems function at their full potential. The responses differed for two emergent species, indicating that within this morphological category, optimal performance will fall at different locations across a depth or water regime gradient. The performance of one species was unaffected by growth in mixture, whereas the other performed better in deep water and worse in shallow.

scholarly journals Performance of Adaptive Unstructured Mesh Modelling in Idealized Advection Cases over Steep Terrains

Atmosphere ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 444 ◽  
Author(s):  
Jinxi Li ◽  
Jie Zheng ◽  
Jiang Zhu ◽  
Fangxin Fang ◽  
Christopher. Pain ◽  
...  
Keyword(s):  
Unstructured Mesh ◽  
Computational Cost ◽  
Adaptive Mesh ◽  
Galerkin Finite Element Method ◽  
Adaptive Meshes ◽  
Galerkin Finite Element ◽  
Computational Costs ◽  
Cut Cell ◽  
Discontinuous Galerkin Finite Element ◽  
Terrain Following

Advection errors are common in basic terrain-following (TF) coordinates. Numerous methods, including the hybrid TF coordinate and smoothing vertical layers, have been proposed to reduce the advection errors. Advection errors are affected by the directions of velocity fields and the complexity of the terrain. In this study, an unstructured adaptive mesh together with the discontinuous Galerkin finite element method is employed to reduce advection errors over steep terrains. To test the capability of adaptive meshes, five two-dimensional (2D) idealized tests are conducted. Then, the results of adaptive meshes are compared with those of cut-cell and TF meshes. The results show that using adaptive meshes reduces the advection errors by one to two orders of magnitude compared to the cut-cell and TF meshes regardless of variations in velocity directions or terrain complexity. Furthermore, adaptive meshes can reduce the advection errors when the tracer moves tangentially along the terrain surface and allows the terrain to be represented without incurring in severe dispersion. Finally, the computational cost is analyzed. To achieve a given tagging criterion level, the adaptive mesh requires fewer nodes, smaller minimum mesh sizes, less runtime and lower proportion between the node numbers used for resolving the tracer and each wavelength than cut-cell and TF meshes, thus reducing the computational costs.

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