Modeling of Fluid Interaction Produced by Water Hammer

2013 ◽  
pp. 27-39
Author(s):  
Kaveh Hariri Asli ◽  
Faig Bakhman Ogli Naghiyev ◽  
Soltan Ali Ogli Aliyev ◽  
Hoosein Hariri Asli
Keyword(s):  
Transient Flow ◽  
Practical Investigations ◽  
The Other ◽  
Computationally Efficient ◽  
Hydraulic Simulation ◽  
Computational Performance ◽  
Difference Form ◽  
Large Water ◽  
Water Transmission ◽  
Fluid Interaction

This paper compares the computational performance of two numerical methods for two models of Transient Flow. One model was defined by method of the Eulerian based expressed in a method of characteristics “MOC”, finite difference form. The other model was defined by method of Regression. Each method was encoded into an existing hydraulic simulation model. Results indicated that the accuracy of the methods was comparable but that the “MOC” was more computationally efficient for analysis of large water transmission line. Practical investigations in this article have shown mainly this tendency.

Modeling of Fluid Interaction Produced by Water Hammer

2011 ◽  
Vol 1 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Kaveh Hariri Asli ◽  
Faig Bakhman Ogli Naghiyev ◽  
Soltan Ali Ogli Aliyev ◽  
Hoosein Hariri Asli
Keyword(s):  
Method Of Characteristics ◽  
Transient Flow ◽  
Practical Investigations ◽  
Computationally Efficient ◽  
Hydraulic Simulation ◽  
Computational Performance ◽  
Difference Form ◽  
Large Water ◽  
Water Transmission ◽  
Fluid Interaction

This paper compares the computational performance of two numerical methods for two models of Transient Flow. One model was defined by method of the Eulerian based expressed in a method of characteristics “MOC”, finite difference form. The other model was defined by method of Regression. Each method was encoded into an existing hydraulic simulation model. Results indicated that the accuracy of the methods was comparable but that the “MOC” was more computationally efficient for analysis of large water transmission line. Practical investigations in this article have shown mainly this tendency.

Multidirectional eigenvalue-based coherence attribute for discontinuity detection

Geophysics ◽  
2021 ◽  
pp. 1-48
Author(s):  
Binpeng Yan ◽  
Ruirui Fang ◽  
Xingguo Huang ◽  
Weiming Ou
Keyword(s):  
Physical Model ◽  
Seismic Data ◽  
Field Data ◽  
Seismic Interpretation ◽  
Covariance Matrices ◽  
The Other ◽  
Computationally Efficient ◽  
Discontinuity Detection ◽  
Geological Discontinuities ◽  
Parallel Direction

The conventional coherence attribute is typically applied to migrated full-stacked seismic data volumes to detect geological discontinuities. Recently, multispectral, multiazimuth, and multioffset coherence attributes have been proposed and implemented with different seismic data volumes of specific frequencies, azimuths, and offsets to enhance discontinuities. Generally, geological anomalies, such as faults and channels, will be better illuminated by a perpendicular rather than a parallel direction for computation. Therefore, we propose a multidirectional eigenvalue-based coherence attribute by establishing multiple covariance matrices along certain different directions on a single post-stack volume. We adopt two methods to compute multidirectional coherence attribute. One is to compute multiple coherence volumes in different directions and to define the minimum as the final multidirectional coherence. This method is time-consuming, but could provide partial and overall discontinuity simultaneously. The other method obtains one coherence volume by summing covariance matrices in different directions, which is computationally efficient, but only provides overall discontinuity. The performance of 3D physical model and field data volumes demonstrates that multidirectional coherence can highlight subtle geologic structures with a higher resolution than conventional coherence. This suggests that multidirectional coherence attribute may serve as an effective tool for detecting the distribution of geologic discontinuities in seismic interpretation.

scholarly journals Solutions to Linear Inverse Problems on the Sphere by Tikhonov Regularization, Wiener filtering and Spectral Smoothing and Combination — A Comparison

2012 ◽  
Vol 2 (1) ◽  
pp. 31-37 ◽  
Author(s):  
L. Sjöberg
Keyword(s):  
Inverse Problems ◽  
Harmonic Analysis ◽  
Tikhonov Regularization ◽  
The Other ◽  
Wiener Filtering ◽  
Data Sets ◽  
Computationally Efficient ◽  
Spectral Leakage ◽  
Linear Inverse Problems ◽  
Spectral Smoothing

Solutions to Linear Inverse Problems on the Sphere by Tikhonov Regularization, Wiener filtering and Spectral Smoothing and Combination — A ComparisonSolutions to linear inverse problems on the sphere, common in geodesy and geophysics, are compared for Tikhonov's method of regularization, Wiener filtering and spectral smoothing and combination as well as harmonic analysis. It is concluded that Wiener and spectral smoothing, although based on different assumptions and target functions, yield the same estimator. Also, provided that the extra information on the signal and error degree variances is available, the standard Tikhonov method is inferior to the other methods, which, in contrast to Tikhonov's approach, match the spectral errors and signals in an optimum way. We show that the corresponding Tikhonov matrix for optimum regularization can only be determined approximately. Moreover, as Tikhonov's method solves an integral equation, it is less computationally efficient than the other methods, which use forward integration. Also harmonic analysis uses direct integration and is not hampered, as previous methods, with spectral leakage. Spectral combination, in addition to filtering, has the advantage of combining different data sets by least squares spectral weighting.

scholarly journals A.2. The book-bound scholar

2013 ◽  
Vol 13 ◽  
pp. 1-28
Author(s):  
Mary Beagon
Keyword(s):  
Natural History ◽  
Empirical Evidence ◽  
Personal Experience ◽  
Literary Culture ◽  
Literary Tradition ◽  
Practical Investigations ◽  
The Other ◽  
Political Dynamics ◽  
Cultural Elite ◽  
Starting Point

This paper takes as its starting point Geoffrey Lloyd's comment that the sources for Pliny's Natural History are 'overwhelmingly literary'. While the encyclopaedic nature of his project might seem to make this inevitable, it is suggested that there are deeper‐seated reasons for Pliny's approach to be found in the attitudes of Rome's cultural élite in the late Republic and early Empire. For this élite, literary culture reflected the socio‐political dynamics of their society, while practical investigations of nature, on the other hand, may for the most part have been associated with the negation of these values. The contrast should not be over‐emphasised: texts on practical subjects could use and exploit empirical evidence and one or two individual enthusiasts may be tentatively posited. However, the breadth and depth of the literary tradition gave the text an authority denied to the particularities of personal experience.

scholarly journals csdR, an R package for differential co-expression analysis

2021 ◽  
Author(s):  
Jakob P. Pettersen ◽  
Eivind Almaas
Keyword(s):  
Data Analysis ◽  
Expression Analysis ◽  
R Package ◽  
Ease Of Use ◽  
The Other ◽  
Gene Pairs ◽  
Computational Performance ◽  
Parallel Speedup ◽  
Multiple Processing ◽  
Number Of Iterations

AbstractBackgroundDifferential co-expression network analysis has become an important tool to gain understanding of biological phenotypes and diseases. The CSD algorithm is a method to generate differential co-expression networks by comparing gene co-expressions from two different conditions. Each of the gene pairs is assigned conserved (C), specific (S) and differentiated (D) scores based on the co-expression of the gene pair between the two conditions. The result of the procedure is a network where the nodes are genes and the links are the gene pairs with the highest C-, S-, and D-scores. However, the existing CSD-implementations suffer from poor computational performance, difficult user procedures and lack of documentation.ResultsWe created the R-package csdR aimed at reaching good performance together with ease of use, sufficient documentation, and with the ability to play well with other tools for data analysis. csdR was benchmarked on a realistic dataset with 20, 645 genes. After verifying that the chosen number of iterations gave sufficient robustness, we tested the performance against the two existing CSD implementations. csdR was superior in performance to one of the implementations, whereas the other did not run. Our implementation can utilize multiple processing cores. However, we were unable to achieve more than ∼ 2.7 parallel speedup with saturation reached at about 10 cores.ConclusionsThe results suggest that csdR is a useful tool for differential co-expression analysis and is able to generate robust results within a workday on datasets of realistic sizes when run on a workstation or compute server.

scholarly journals Vectorised Spreading Activation algorithm for centrality measurement

2011 ◽  
Vol 59 (7) ◽  
pp. 469-476 ◽  
Author(s):  
Alexander Troussov ◽  
František Dařena ◽  
Jan Žižka ◽  
Denis Parra ◽  
Peter Brusilovsky
Keyword(s):  
Network Flows ◽  
State Of The Art ◽  
Network Models ◽  
The Other ◽  
Spreading Activation ◽  
Computationally Efficient ◽  
Current State ◽  
Initial Seed ◽  
Spreading Activation Algorithm ◽  
Computationally Efficient Algorithms

Spreading Activation is a family of graph-based algorithms widely used in areas such as information retrieval, epidemic models, and recommender systems. In this paper we introduce a novel Spreading Activation (SA) method that we call Vectorised Spreading Activation (VSA). VSA algorithms, like “traditional” SA algorithms, iteratively propagate the activation from the initially activated set of nodes to the other nodes in a network through outward links. The level of the node’s activation could be used as a centrality measurement in accordance with dynamic model-based view of centrality that focuses on the outcomes for nodes in a network where something is flowing from node to node across the edges. Representing the activation by vectors allows the use of the information about various dimensionalities of the flow and the dynamic of the flow. In this capacity, VSA algorithms can model multitude of complex multidimensional network flows. We present the results of numerical simulations on small synthetic social networks and multi­dimensional network models of folksonomies which show that the results of VSA propagation are more sensitive to the positions of the initial seed and to the community structure of the network than the results produced by traditional SA algorithms. We tentatively conclude that the VSA methods could be instrumental to develop scalable and computationally efficient algorithms which could achieve synergy between computation of centrality indexes with detection of community structures in networks. Based on our preliminary results and on improvements made over previous studies, we foresee advances and applications in the current state of the art of this family of algorithms and their applications to centrality measurement.

scholarly journals Computationally-Efficient Distributed Algorithms of Navigation of Teams of Autonomous UAVs for 3D Coverage and Flocking

Drones ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 124
Author(s):  
Taha Elmokadem ◽  
Andrey V. Savkin
Keyword(s):  
Obstacle Avoidance ◽  
Precision Agriculture ◽  
Control Strategies ◽  
Autonomous Underwater Vehicles ◽  
Three Dimensional ◽  
Problem Formulation ◽  
Computationally Efficient ◽  
Control Approach ◽  
Computational Performance ◽  
Coverage Problems

This paper proposes novel distributed control methods to address coverage and flocking problems in three-dimensional (3D) environments using multiple unmanned aerial vehicles (UAVs). Two classes of coverage problems are considered in this work, namely barrier and sweep problems. Additionally, the approach is also applied to general 3D flocking problems for advanced swarm behavior. The proposed control strategies adopt a region-based control approach based on Voronoi partitions to ensure collision-free self-deployment and coordinated movement of all vehicles within a 3D region. It provides robustness for the multi-vehicle system against vehicles’ failure. It is also computationally-efficient to ensure scalability, and it handles obstacle avoidance on a higher level to avoid conflicts in control with the inter-vehicle collision avoidance objective. The problem formulation is rather general considering mobile robots navigating in 3D spaces, which makes the proposed approach applicable to different UAV types and autonomous underwater vehicles (AUVs). However, implementation details have also been shown considering quadrotor-type UAVs for an example application in precision agriculture. Validation of the proposed methods have been performed using several simulations considering different simulation platforms such as MATLAB and Gazebo. Software-in-the-loop simulations were carried out to asses the real-time computational performance of the methods showing the actual implementation with quadrotors using C++ and the Robot Operating System (ROS) framework. Good results were obtained validating the performance of the suggested methods for coverage and flocking scenarios in 3D using systems with different sizes up to 100 vehicles. Some scenarios considering obstacle avoidance and robustness against vehicles’ failure were also used.

A New Hypervolume-based Evolutionary Algorithm for Many-objective Optimization

2020 ◽  
Author(s):  
Ke Shang ◽  
Hisao Ishibuchi
Keyword(s):  
Optimization Algorithm ◽  
State Of The Art ◽  
Experimental Studies ◽  
The Other ◽  
Tensor Structure ◽  
Multi Objective Optimization ◽  
Computationally Efficient ◽  
The Core ◽  
Core Idea ◽  
R2 Indicator

<div> <div> <div> <p>In this paper, a new hypervolume-based evolutionary multi-objective optimization algorithm (EMOA), namely R2HCA-EMOA (R2-based Hypervolume Contribution Approximation EMOA), is proposed for many-objective optimization. The core idea of the algorithm is to use an R2 indicator variant to approximate the hypervolume contribution. The basic framework of the proposed algorithm is the same as SMS- EMOA. In order to make the algorithm computationally efficient, a utility tensor structure is introduced for the calculation of the R2 indicator variant. Moreover, a normalization mechanism is incorporated into R2HCA-EMOA to enhance the performance of the algorithm. Through experimental studies, R2HCA-EMOA is compared with three hypervolume-based EMOAs and several other state-of-the-art EMOAs on 5-, 10- and 15-objective DTLZ, WFG problems and their minus versions. Our results show that R2HCA-EMOA is more efficient than the other hypervolume-based EMOAs, and is superior to all the compared state-of-the-art EMOAs. </p> </div> </div> </div>

scholarly journals Three-Dimensional Hydromechanical Modeling during Shearing by Nonuniform Crust Movement

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Yuqing Zhao ◽  
You-Kuan Zhang ◽  
Xiuyu Liang
Keyword(s):  
Fluid Flow ◽  
Pore Pressure ◽  
Fault Zone ◽  
Numerical Models ◽  
Three Dimensional ◽  
Practical Investigations ◽  
Geological Formation ◽  
Distribution Of Stress ◽  
Coupling Processes ◽  
Fluid Interaction

Hydromechanical modeling of a geological formation under shearing by the nonuniform crust movement during 10000 years was carried out to investigate the solid stress and pore pressure coupling processes of the formation from the intact to the fractured or faulted. Two three-dimensional numerical models were built and velocities in opposite directions were applied on the boundaries to produce the shearing due to the nonuniform crust movement. The results show that the stress and pore pressure became more and more concentrated in and around the middle of the formation as time progresses. In Model I with no fault, stress and pore pressure are concentrated in the middle of the model during shearing; however, in Model II with a fault zone of weakened mechanical properties, they are more complex and concentrated along the sides of the fault zone and the magnitudes decreased. The distribution of stress determines pore pressure which in turn controls fluid flow. Fluid flow occurs in the middle in Model I but along the sides of the fault zone in Model II. The results of this study improve our understanding of the rock-fluid interaction processes affected by crustal movement and may guide practical investigations in geological formations.

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