scholarly journals On the efficiency of coupled discrete-continuum modelling analyses of cemented materials

2021 ◽  
Author(s):  
Jinhui Zheng ◽  
◽  
Matteo Ciantia ◽  
Jonathan Knappett ◽  
◽  
...  
Keyword(s):  
Hybrid Methods ◽  
Elastic Response ◽  
Discrete Element Modelling ◽  
Zone Method ◽  
Bending Tests ◽  
Coupled Wall ◽  
Advantages And Disadvantages ◽  
Finite Differences Method ◽  
Wall Zone ◽  
Coupling Approach

Computational load of discrete element modelling (DEM) simulations is known to increase with the number of particles. To improve the computational efficiency hybrid methods using continuous elements in the far-field, have been developed to decrease the number of discrete particles required for the model. In the present work, the performance of using such coupling methods is investigated. In particular, the coupled wall method, known as the “wall-zone” method when coupling DEM and the continuum Finite Differences Method (FDM) using the Itasca commercial codes PFC and FLAC respectively, is here analysed. To determine the accuracy and the efficiency of such a coupling approach, 3-point bending tests of cemented materials are simulated numerically. To validate the coupling accuracy first the elastic response of the beam is considered. The advantage of employing such a coupling method is then investigated by loading the beam until failure. Finally, comparing the results between DEM, DEM-FDM coupled and FDM models, the advantages and disadvantages of each method are outlined.

scholarly journals STUDY METHODS FOR MONITORING OF TELECOMMUNICATION SYSTEMS

2020 ◽  
Vol 6 (1) ◽  
pp. 143-148
Author(s):  
Mikhail M. Zykin ◽  
Sergey N. Novikov
Keyword(s):  
Hybrid Methods ◽  
Optimal Operation ◽  
Monitoring Method ◽  
Advantages And Disadvantages ◽  
Network State ◽  
Optimal Monitoring ◽  
Telecommunication Systems ◽  
Telecommunications Network ◽  
Routing Tables ◽  
Different Levels

The article describes main steps for centralizing routing table databases. Advantages and disadvantages of databases formed at different levels of centralization are described. Main methods of forming routing tables are described. The advantages and disadvantages of each method are indicated. There are also examples of network protocols that are used to implement a particular method for generating databases about the network state. Possible hybrid methods are identified by combining standard methods for creating databases describing the network state. To ensure optimal operation of the telecommunications network, the optimal monitoring method should be selected based on the degree of centralization and the method for creating a database of routing tables. Depending on the scale of the network and the degree of centralization of its resources, it is needed to choose the best method for monitoring the network.

scholarly journals Artifact Removal Methods in EEG Recordings: A Review

2021 ◽  
Vol 20 ◽  
pp. 35-56
Author(s):  
Mariyadasu Mathe ◽  
Padmaja Mididoddi ◽  
Battula Tirumala Krishna
Keyword(s):  
Wavelet Transform ◽  
Spectrum Analysis ◽  
Hybrid Methods ◽  
Singular Spectrum Analysis ◽  
Discrete Wavelet ◽  
Eeg Signals ◽  
Artifact Removal ◽  
Filtering Method ◽  
Advantages And Disadvantages ◽  
Singular Spectrum

To obtain the correct analysis of electroencephalogram (EEG) signals, non-physiological and physiological artifacts should be removed from EEG signals. This study aims to give an overview on the existing methodology for removing physiological artifacts, e.g., ocular, cardiac, and muscle artifacts. The datasets, simulation platforms, and performance measures of artifact removal methods in previous related research are summarized. The advantages and disadvantages of each technique are discussed, including regression method, filtering method, blind source separation (BSS), wavelet transform (WT), empirical mode decomposition (EMD), singular spectrum analysis (SSA), and independent vector analysis (IVA). Also, the applications of hybrid approaches are presented, including discrete wavelet transform - adaptive filtering method (DWT-AFM), DWT-BSS, EMD-BSS, singular spectrum analysis - adaptive noise canceler (SSA-ANC), SSA-BSS, and EMD-IVA. Finally, a comparative analysis for these existing methods is provided based on their performance and merits. The result shows that hybrid methods can remove the artifacts more effectively than individual methods.

scholarly journals On the Comparison of Gauss and Hybrid Methods and their Application to Calculation of Definite Integrals

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Necessary Conditions ◽  
Hybrid Methods ◽  
Definite Integral ◽  
Implicit Methods ◽  
Definite Integrals ◽  
Advantages And Disadvantages ◽  
Chebyshev Method ◽  
Gauss Method ◽  
Gauss Quadrature Formula ◽  
To Receive

As is known there is the wide class of methods for calculation of the definite integrals constructed by the well-known scientists as Newton, Gauss, Chebyshev, Cotes, Simpson, Krylov and etc. It seems that to receive a new result in this area is impossible. The aim of this work is the applied some general form of hybrid methods to computation of definite integral and compares that with the Gauss method. The generalization of the Gauss quadrature formula have been fulfilled in two directions. One of these directions is the using of the implicit methods and the other is the using of the advanced (forward-jumping) methods. Here have compared these methods by shown its advantages and disadvantages in the results of which have recommended to use the implicit method with the special structure. And also are constructed methods, which have applied to calculation of the definite integral with the symmetric bounders. As is known, one of the popular methods for calculation of the definite integrals with the symmetric bounders is the Chebyshev method. Therefore, here have defined some relations between of the above mentioned methods. For the application constructed, here methods are defined the necessary conditions for its convergence. The receive results have illustrated by calculation the values for some model integral using the methods with the degree p  8.

scholarly journals Experimental Investigation of the Shear Strength of RC Beams Extracted from an Old Structure and Strengthened by Carbon FRP U-Strips

2018 ◽  
Vol 8 (7) ◽  
pp. 1182 ◽  
Author(s):  
Davide Lavorato ◽  
Camillo Nuti ◽  
Silvia Santini
Keyword(s):  
Shear Strength ◽  
Point Load ◽  
Fiber Reinforced Polymer ◽  
Elastic Response ◽  
Bending Tests ◽  
Brittle Behavior ◽  
Reinforced Polymer ◽  
Beam Shear ◽  
Rc Building ◽  
Steel Rebars

In recent years, old reinforced concrete (RC) buildings have increasingly been protected as historic symbols in Italy. The conversion of these buildings can resolve the increasing need for new structures, reducing much social, economic, and environmental impact. Retrofitting solutions by carbon fiber reinforced polymer (CFRP) reinforcements are very common nowadays. Code predictions present uncertainties due to the brittle behavior and the debonding of CFRP strips resulting from concrete cracking. Therefore, especially in the case of old beams, experimental validation is necessary. This paper deals the experimental evaluation of the shear strength of two beams extracted from an old RC building in Rome built in 1929 with modest-quality concrete. Preliminary tests were carried out to evaluate the beam elastic response and the material characteristics. These beams were tested until failure (three-point load shear/bending tests) after strengthening for shear by CFRP U-jacketing and for bending by new steel rebars. The results obtained, together with the extensive data taken from the literature, were compared with the predictions by design code equations. The influence of construction details on beam shear strength and the experimental maximum CFRP strain were also analyzed. Code predictions can be effective to estimate the shear strength of the retrofitted beams.

Analytical and Numerical Calculation of the Force and Power Requirements for Air Bending of Structured Sheet Metals

2011 ◽  
Vol 473 ◽  
pp. 602-609 ◽  
Author(s):  
V. Malikov ◽  
Ralf Ossenbrink ◽  
B. Viehweger ◽  
Vesselin Michailov
Keyword(s):  
Analytical Calculation ◽  
Simulation Models ◽  
Measuring System ◽  
Sheet Metals ◽  
Bending Tests ◽  
Air Bending ◽  
Advantages And Disadvantages ◽  
Element Simulation ◽  
Optical Displacement ◽  
Hydroforming Process

Structured sheet metals with regular bumps offer higher stiffness compared to smooth sheet metals. They can be produced by a hydroforming process. The application of the structured sheet metals, however, is inhibited by the lack of knowledge for the subsequent processing steps. In this paper, the force and power requirements for air bending of structured sheet metals are calculated with a Finite Element Simulation (FE) and an analytical approach. In the first step, the hydroforming manufacturing process of the structured sheet metals is simulated in order to predict the exact geometry and the change in the material properties. Following, air bending simulations have been done taking into account the results of the hydroforming simulation. The FE-Simulations have been carried out with the software package LS-DYNA. The simulation models are validated with the optical displacement measuring system ARGUS and by a series of bending tests. For the analytical calculation the model based on the bending theory is adapted by simplifying the cross section of the structured sheet metals. The results of the FE-Simulation, the analytic calculation and the experiments are compared. The advantages and disadvantages as well as the application areas of the considered methods are indicated.

Islanding Detection Parameters for Integrated Distributed Generation

2020 ◽  
Vol 13 ◽  
Author(s):  
S. Govinda Raju ◽  
K. Harinadha Reddy ◽  
Ch. Rami Reddy
Keyword(s):  
Power Quality ◽  
Distributed Generation ◽  
Hybrid Methods ◽  
Renewable Energy Sources ◽  
Detection Methods ◽  
Islanding Detection ◽  
Detection Zone ◽  
Advantages And Disadvantages ◽  
The Stability ◽  
Consumption Demand

Background: The growth of renewable energy sources is increasing in the world to meet the energy consumption demand. The major problem after the integration of renewable sources is islanding. The islanding is not safe for equipment and customers. As per Distributed Generation (DG) interconnection standards, it should be detected within 2 seconds. Objective: This paper presents the review of various islanding detection methods for increasing the stability of islanded DG. This will help future researchers for selecting the best islanding detection method with zero NDZ. Methods & Results: The islanding detection methods are classified as local and remote techniques. The local techniques are again classified as active, passive and hybrid methods. Each method is presented with their islanding detection time, power quality issues, Non Detection Zone (NDZ), advantages and disadvantages. Conclusion: The fuzzy based artificial intelligence with Particle Swarm Optimization (PSO) passive methods have been reduced the NDZ to zero and increase the stability of DG without degrading the power quality as active and passive methods.

GROUNDWATER FLOW MODELlING USING the FINITE DIFFERENCES METHOD AND the FINITE ELEMENTS METHOD – COMPARATIVE MODEL STUDIES

2018 ◽  
Vol 471 ◽  
pp. 201-208
Author(s):  
Robert ZDECHLIK ◽  
Małgorzata PARTYKA
Keyword(s):  
Finite Elements ◽  
Groundwater Flow ◽  
Finite Differences ◽  
Finite Elements Method ◽  
Advantages And Disadvantages ◽  
Flow Modelling ◽  
Hydrogeological Conditions ◽  
Groundwater Flow Modelling ◽  
Finite Differences Method ◽  
The Impact

The filtration of groundwater is a complicated process, which is determined by natural environmental factors (hydrogeological conditions) and anthropogenic impacts. Reliable predictions of the impact of the established extortions on the groundwater environment require the use of an appropriate research method that will allow for a precise representation of groundwater circulation. Such methods include numerical modelling of filtration processes, using a mathematical description of groundwater flow, based on assumed parameters and boundary conditions. For groundwater flow modelling, software based on the finite differences method FDM, using Modflow simulators, is most commonly used. Due to the numerous advantages, mainly in terms of greater precision in the representation of the complex geometry of the aquifers and objects affecting the water circulation, the alternative FEM finite elements method is becoming increasingly important. The article presents characteristic features of modelling using both methods. Based on the established imaginary research site, representing typical valley hydrogeological conditions, the paper presents the methodology of model implementation and numerical calculations of water flow using FDM and FEM methods, each in two variants of grid density. Obtained results are presented, with an attempt to compare the advantages and disadvantages of both methods.

scholarly journals A New Hybrid Prognostic Methodology

2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Omer F. Eker ◽  
Fatih Camci ◽  
Ian K. Jennions
Keyword(s):  
Hybrid Methods ◽  
Industrial Applications ◽  
Remaining Useful Life ◽  
Data Driven ◽  
Prognostic Models ◽  
Advantages And Disadvantages ◽  
Minimal Data ◽  
Useful Life ◽  
Filter Clogging ◽  
Short Term Prediction

Methodologies for prognostics usually centre on physics-based or data-driven approaches. Both have advantages and disadvantages, but accurate prediction relies on extensive data being available. For industrial applications, this is very rarely the case, and hence the chosen method’s performance can deteriorate quite markedly from optimal. For this reason, a hybrid methodology, merging physics-based and data-driven approaches, has been developed and is reported here. Most, if not all, hybrid methods apply physics-based and data-driven approaches in different steps of the prognostics process (i.e. state estimation and state forecasting). The presented technique combines both methods in forecasting, and integrates the short-term prediction of a physics-based model with the longer-term projection of a similarity-based data-driven model, to obtain remaining useful life estimation. The proposed hybrid prognostic methodology has been tested on two engineering datasets, one for crack growth and the other for filter clogging. The performance of the presented methodology has been evaluated by comparing remaining useful life estimations obtained from both hybrid and individual prognostic models. The results show that the presented methodology improves accuracy, robustness and applicability, especially in the case of minimal data being available.

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