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Symmetry in Applied Continuous Mechanics 2022

by

Marin Marin

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Sorin Vlase

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Ibrahim A. Abbas

Symmetry 2022, 14(11), 2427; https://doi.org/10.3390/sym14112427 - 16 Nov 2022

Viewed by 636

Abstract

Symmetry leading to interesting properties of mechanical systems has interesting properties and various applications in the field of engineering [...] Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

Research

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Open AccessArticle

Experimental and Numerical Studies of the Heat Transfer in Thin-Walled Rectangular Tubes under Fire

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Symmetry 2022, 14(9), 1781; https://doi.org/10.3390/sym14091781 - 26 Aug 2022

Cited by 1 | Viewed by 854

Abstract

The paper studies, experimentally and numerically, the fire behavior of some structural elements of symmetric-tubular (rectangular in this study) shapes using modern dimensional analysis (MDA). A model at a certain scale of the real prototype is analyzed in order to obtain its response [...] Read more.

The paper studies, experimentally and numerically, the fire behavior of some structural elements of symmetric-tubular (rectangular in this study) shapes using modern dimensional analysis (MDA). A model at a certain scale of the real prototype is analyzed in order to obtain its response in case of fires. Experimental measurements are performed on a 1:10 scale model of a real support pillar and compared with the results of the numerical simulation. The obtained results can have useful applications in engineering practice, allowing fast obtaining of results with minimal costs. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

Burr XII Distribution for Disease Data Analysis in the Presence of a Partially Observed Failure Mode

by

Fatimah E. Almuhayfith

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Jumanah Ahmed Darwish

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Randa Alharbi

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Marin Marin

Symmetry 2022, 14(7), 1298; https://doi.org/10.3390/sym14071298 - 22 Jun 2022

Cited by 2 | Viewed by 1095

Abstract

Modeling competing failure modes is an important problem in engineering and survival analyses. Competing failure modes are partially observed in many applications and often pose a modeling challenge. This study discusses the inference for partially observed failure modes assuming a Burr XII distribution. [...] Read more.

Modeling competing failure modes is an important problem in engineering and survival analyses. Competing failure modes are partially observed in many applications and often pose a modeling challenge. This study discusses the inference for partially observed failure modes assuming a Burr XII distribution. In particular, we consider two failure modes, and the failure time data are collected under a hybrid type I censoring scheme. The model parameters are estimated using maximum likelihood and Bayesian methods under a symmetric squared error loss function, whereas the intervals estimation is done with three methods: asymptotic and credible confidence intervals. Besides a simulation study, a real-life data set is taken from individuals who live in an environment with several diseases to present the utility of the work. Additionally, a simulation study is constructed to measure and compare different estimation methods. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

T-Stress Evaluation Based Cracking of Pipes Using an Extended Isogeometric Analysis (X-IGA)

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Maria Luminita Scutaru

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Sorin Vlase

Symmetry 2022, 14(5), 1065; https://doi.org/10.3390/sym14051065 - 23 May 2022

Cited by 3 | Viewed by 1299

Abstract

The aim of this study is to investigate the problem of pipe cracking based on T-stress analysis and the influence of other parameters, using a numerical computation performed by extended isogeometric analysis (X-IGA). This article examines the T-stress, which defines the [...] Read more.

The aim of this study is to investigate the problem of pipe cracking based on T-stress analysis and the influence of other parameters, using a numerical computation performed by extended isogeometric analysis (X-IGA). This article examines the T-stress, which defines the second term of the Williams’ series expansion. T-stress provides effective elastic modeling at the crack tip. Using the extended iso-geometric analysis (X-IGA), we determined the distribution of T-stress at the crack tip in a pipe under internal pressure as a function of internal pressure, crack size, and Poisson’s ratio. To validate the promising findings, the results are expanded with a comparison to the extended finite element (X-FEM) method and existing research in this field, and we obtained an error between 0.2% and 4.6%. This work demonstrated the significance of T-stress in fracture description, the effect of Poisson’s ratio and size on T-stress, and that X-IGA provided accurate numerical results by precisely describing the geometry of the crack and enriching it. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

Analytical Solutions of Nonlocal Thermoelastic Interaction on Semi-Infinite Mediums Induced by Ramp-Type Heating

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Symmetry 2022, 14(5), 864; https://doi.org/10.3390/sym14050864 - 22 Apr 2022

Cited by 2 | Viewed by 965

Abstract

A novel nonlocal model with one thermal relaxation time is presented to investigate the propagation of waves in a thermoelastic semi-infinite medium. We used Eringen’s theory of the nonlocal continuum to develop these models. Analytical solutions in all physical quantities are provided by [...] Read more.

A novel nonlocal model with one thermal relaxation time is presented to investigate the propagation of waves in a thermoelastic semi-infinite medium. We used Eringen’s theory of the nonlocal continuum to develop these models. Analytical solutions in all physical quantities are provided by using Laplace transforms and eigenvalue techniques. All physical quantities are presented as symmetric and asymmetric tensors. The temperature, the displacement, and the stress variations in semi-infinite materials have been calculated. The effects of nonlocal parameters, ramp type heating, and the thermal relaxation times on the wave propagation distribution of physical fields for mediums are graphically displayed and analyzed. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

Modern Method to Analyze the Heat Transfer in a Symmetric Metallic Beam with Hole

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Symmetry 2022, 14(4), 769; https://doi.org/10.3390/sym14040769 - 07 Apr 2022

Cited by 4 | Viewed by 840

Abstract

The paper aims to use Modern Dimensional Analysis to study the heat transmission through a rectangular bar with a hole. The problem is very important for monitoring a structure, made of such bars, to protect it from fire. The original part of the [...] Read more.

The paper aims to use Modern Dimensional Analysis to study the heat transmission through a rectangular bar with a hole. The problem is very important for monitoring a structure, made of such bars, to protect it from fire. The original part of the work is represented by the application of this nonconventional method in the field of heat transfer in bars of rectangular-tubular section. During system heating, the properties of the material change dramatically at high temperatures, which can lead to the collapse of the entire system. The Laws of the Model, further applied to the two sets of independent variables, provide the complete sets of dimensionless variables, which cannot be offered by any of the classical methods (such as Geometric Analogy, Theory of Similarity, and Classical Dimensional Analysis). The validation of the method was made experimental on both unprotected structural elements and those thermally protected with layers of intumescent paints, widely used in the field of fire protection. Finite Element Method was too applied to obtain the field of temperature in order to validate the model. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

Statistical Inference of Jointly Type-II Lifetime Samples under Weibull Competing Risks Models

by

Abdulaziz S. Alghamdi

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Gamal Amin Abd-Elmougod

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Debasis Kundu

and

Marin Marin

Symmetry 2022, 14(4), 701; https://doi.org/10.3390/sym14040701 - 30 Mar 2022

Cited by 7 | Viewed by 1321

Abstract

In this paper, we develop statistical inference of competing risks samples which are collected under a joint Type-II censoring scheme of products with Weibull lifetime distributions. These inferences are drawn from two independent fatal risks and come from two different lines of production [...] Read more.

In this paper, we develop statistical inference of competing risks samples which are collected under a joint Type-II censoring scheme of products with Weibull lifetime distributions. These inferences are drawn from two independent fatal risks and come from two different lines of production with the same facility. The model parameters and the parameters of life (reliability and hazard rate functions) are estimated using maximum likelihood (ML), bootstrap and Bayes methods. Additionally, we constructed asymptotic ML confidence intervals, bootstrap confidence intervals and Bayes credible intervals. Furthermore, the theoretical results are assessed and compared through Monte Carlo simulations. Finally, one real data set is analyzed under the proposed model for illustrative purpose. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessEditor’s ChoiceArticle

Some Results in the Theory of a Cosserat Thermoelastic Body with Microtemperatures and Inner Structure

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Symmetry 2022, 14(3), 511; https://doi.org/10.3390/sym14030511 - 02 Mar 2022

Cited by 4 | Viewed by 1801

Abstract

This study is concerned with the theory of Cosserat thermoelastic media, whose micro-particles possess microtemperatures. The mixed initial boundary value problem considered in this context is transformed in a temporally evolutionary equation on a Hilbert space. Using some results from the theory of [...] Read more.

This study is concerned with the theory of Cosserat thermoelastic media, whose micro-particles possess microtemperatures. The mixed initial boundary value problem considered in this context is transformed in a temporally evolutionary equation on a Hilbert space. Using some results from the theory of semigroups, the existence and uniqueness of solution is proved. In the same manner, it approached the continuous dependence of the solution upon initial data and loads. From what we have studied, neither on the internet nor in the databases, we have not found qualitative issues addressed regarding the mixed problem in the context of the theory of thermoelasticity of Cosserat environments, in which the contribution of inner structure and microtemperatures are taken into account. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

Open AccessArticle

Predication and Photon Statistics of a Three-Level System in the Photon Added Negative Binomial Distribution

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Symmetry 2022, 14(2), 284; https://doi.org/10.3390/sym14020284 - 31 Jan 2022

Cited by 1 | Viewed by 1349

Abstract

Statistical and artificial neural network models are applied to forecast the quantum scheme of a three-level atomic system (3LAS) and field, initially following a photon added negative binomial distribution (PANBD). The Mandel parameter is used to detect the photon statistics of a radiation [...] Read more.

Statistical and artificial neural network models are applied to forecast the quantum scheme of a three-level atomic system (3LAS) and field, initially following a photon added negative binomial distribution (PANBD). The Mandel parameter is used to detect the photon statistics of a radiation field. Explicit forms of the PANBD are given. The prediction of the Mandel parameter, atomic probability of the 3LAS in the upper state, and von Neumann entropy are obtained using time series and artificial neural network methods. The influence of probability success photons and the number of added photons to the NBD are examined. The total density matrix is used to compute and analyze the time evolution of the initial photonic negative binomial probability distribution that governs the 3LAS–field photon entanglement behavior. It is shown that the statistical quantities are strongly affected by probability success photons and the number of added photons to the NBD. Also, the prediction of quantum entropy is achieved by the time series and neural network. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

Tracking and Monitoring of the Alignment System Used for Nuclear Physics Experiments

by

Paul Nicolae Borza

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Sorin Vlase

Symmetry 2022, 14(1), 47; https://doi.org/10.3390/sym14010047 - 31 Dec 2021

Cited by 1 | Viewed by 920

Abstract

The ELI-NP (Extreme Light Intensity—Nuclear Physics) project, developed at the Horia Hulubei National Institute for RD in Physics and Nuclear Engineering (IFIN-HH), has included one component dedicated to the study of interactions between brilliant gamma-ray and matter, with applications in nuclear physics and [...] Read more.

The ELI-NP (Extreme Light Intensity—Nuclear Physics) project, developed at the Horia Hulubei National Institute for RD in Physics and Nuclear Engineering (IFIN-HH), has included one component dedicated to the study of interactions between brilliant gamma-ray and matter, with applications in nuclear physics and the science of materials. The paper is focused on the interaction chamber, an important part of the facility which hosts the experiment’s samples. The interaction chamber is endowed with a mobile sample support (holder), which automatically tracks the γ-ray beam. The γ-ray radiation source presents a slight variation of the direction of the emitted radiation in time. The built system ensures the permanent collimation between the γ-ray beam and the sample that is being investigated. This is done with two electric motors, which have a symmetrical movement with respect to the center of a rectangle. The specific measures taken by the design and implementation that permit to reach performances of tracking system are emphasized in the paper. The methodology considers the relative displacement between the detectors with which the laboratory is equipped and the absolute position in space of the sample boundary. The control of this motion is designed to respect the symmetry of the system. Both facets of the project (hardware and software) are detailed, emphasizing the way in which the designers ensured compliance with the system of real-time operation conditions of the tracking and monitoring system. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

Effects of Energy Dissipation and Deformation Function on the Entanglement, Photon Statistics and Quantum Fisher Information of Three-Level Atom in Photon-Added Coherent States for Morse Potential

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Symmetry 2021, 13(11), 2188; https://doi.org/10.3390/sym13112188 - 16 Nov 2021

Cited by 3 | Viewed by 1099

Abstract

The present research paper considers a three-level atom (3LA) that interacts with a field mode primarily in a photon-added coherent state of Morse potential (PACSMP). The dynamics of entanglement, the photon statistics, and the quantum Fisher information are investigated. The statistics of field [...] Read more.

The present research paper considers a three-level atom (3LA) that interacts with a field mode primarily in a photon-added coherent state of Morse potential (PACSMP). The dynamics of entanglement, the photon statistics, and the quantum Fisher information are investigated. The statistics of field photons are discussed by evaluating the Mandel parameter. We check the influence of the energy dissipation and intensity-dependent function. Finally, we detect the relationship between the entanglement, the field’s nonclassical characteristics, and atomic quantum Fisher information throughout the evolution of time. The findings illustrate the important role of the number of added photons and CSMP in affecting the entanglement’s time evolution, the quantum Fisher information, and the Mandel parameter. Based on the obtained results, we reached significant physical phenomena, including the sudden birth and death of the nonlocal correlation between atom-Morse potential field structures. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

Adder Box Used in the Heavy Trucks Transmission Noise Reduction

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Andrei Bencze

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Maria Luminița Scutaru

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Marin Marin

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Sorin Vlase

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Ana Toderiță

Symmetry 2021, 13(11), 2165; https://doi.org/10.3390/sym13112165 - 11 Nov 2021

Cited by 4 | Viewed by 1221

Abstract

The paper aims to analyze the vibrations of a summing box, used in heavy vehicles. An experimental setup is proposed and used for the analysis of these vibrations transmitted by the box housing, based on the measurement of the mechanical impedance. It is [...] Read more.

The paper aims to analyze the vibrations of a summing box, used in heavy vehicles. An experimental setup is proposed and used for the analysis of these vibrations transmitted by the box housing, based on the measurement of the mechanical impedance. It is then shown that a simpler measurement, namely that of the generated noise spectrum, can provide equally useful results, with less effort and in a shorter time. The experimental setup is much simpler, involving a sonometer arranged in the experimental assembly. The symmetry of the box allows us to facilitate the execution of the experimental assembly, and the use of the symmetrical structure to facilitate the calculation of vibrations. The results obtained using this method in the case of a redesigned adder box are presented in the paper. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

Use of the Symmetries in the Study of Vibration Response of a Hollow Cylinder

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Symmetry 2021, 13(11), 2145; https://doi.org/10.3390/sym13112145 - 10 Nov 2021

Cited by 3 | Viewed by 1361

Abstract

The paper studies the vibration response of an elastic solid that has geometric symmetries. These determine special properties of the equations of motion of such a system, presented in the case of a cylindrical body (hollow cylinder). The properties of the eigenvalues and [...] Read more.

The paper studies the vibration response of an elastic solid that has geometric symmetries. These determine special properties of the equations of motion of such a system, presented in the case of a cylindrical body (hollow cylinder). The properties of the eigenvalues and eigenmodes of these systems are theoretically established. A validation of these results is made using the finite element method. The use of the obtained results can lead to an easing of the vibration analysis of such a system and, consequently, to the decrease of the cost related to the design and manufacture of such a structure. The properties presented and demonstrated in the paper can simplify the numerical calculation and experimental verifications of such a structure. Serving these symmetries, the computation cost decrease substantially and will depend not in the number of the identical parts. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

The Influence of Voids in the Vibrations of Bodies with Dipolar Structure

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Marin Marin

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Sorin Vlase

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Adina Chirila

Symmetry 2021, 13(10), 1804; https://doi.org/10.3390/sym13101804 - 28 Sep 2021

Cited by 2 | Viewed by 777

Abstract

In our study we analyse the vibration of a right cylinder which consists of an elastic material with dipolar structure and has pores. One end of this cylinder is subjected to an excitation, harmonically in time. The other end of the cylinder and [...] Read more.

In our study we analyse the vibration of a right cylinder which consists of an elastic material with dipolar structure and has pores. One end of this cylinder is subjected to an excitation, harmonically in time. The other end of the cylinder and its lateral surface are free of loads. We prove that the presence of the voids does not affect the spatial decay of effects away from the excited end, if the harmonic excitation level is below a predetermined threshold. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

Open AccessArticle

A SPH-GFDM Coupled Method for Elasticity Analysis

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Symmetry 2021, 13(10), 1774; https://doi.org/10.3390/sym13101774 - 24 Sep 2021

Cited by 2 | Viewed by 1230

Abstract

SPH (smoothed particle hydrodynamics) is one of the oldest meshless methods used to simulate mechanics of continuum media. Despite its great advantage over the traditional grid-based method, implementing boundary conditions in SPH is not easy and the accuracy near the boundary is low. [...] Read more.

SPH (smoothed particle hydrodynamics) is one of the oldest meshless methods used to simulate mechanics of continuum media. Despite its great advantage over the traditional grid-based method, implementing boundary conditions in SPH is not easy and the accuracy near the boundary is low. When SPH is applied to problems for elasticity, the displacement or stress boundary conditions should be suitably handled in order to achieve fast convergence and acceptable numerical accuracy. The GFDM (generalized finite difference method) can derive explicit formulae for required partial derivatives of field variables. Hence, a SPH–GFDM coupled method is developed to overcome the disadvantage in SPH. This coupled method is applied to 2-D elastic analysis in both symmetric and asymmetric computational domains. The accuracy of this method is demonstrated by the excellent agreement with the results obtained from FEM (finite element method) regardless of the symmetry of the computational domain. When the computational domain is multiply connected, this method needs to be further improved. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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Open AccessArticle

A Kinematical Analysis of the Flap and Wing Mechanism of a Light Sport Aircraft Using Topological Models

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Sorin Vlase

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Ion-Marius Ghiţescu

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Marius Paun

Symmetry 2021, 13(7), 1243; https://doi.org/10.3390/sym13071243 - 10 Jul 2021

Cited by 1 | Viewed by 1688

Abstract

In this, paper, we propose a method of kinematic analysis of a planar mechanism with application to the flap and wing mechanism of a light sport aircraft. A topological model is used to describe a mechanical system, which is a model that allows [...] Read more.

In this, paper, we propose a method of kinematic analysis of a planar mechanism with application to the flap and wing mechanism of a light sport aircraft. A topological model is used to describe a mechanical system, which is a model that allows the study of the maneuverability of the system. The proposed algorithm is applied to determine the velocity and acceleration field of this multibody mechanical system. The graph associated with the mechanical system is generated in a new formulation and based on it, the fundamental loops of the graph are identified (corresponding to the independent loops of the mechanism), the equations for closing vectorial contours are written, and the kinematic conditions for determining velocities and accelerations and the associated linear systems are solved, which provides the field of speeds and accelerations. Graph Theory is applied at a kinematic level and not at a dynamic level, as in previous studies. A practical application for the kinematic analysis of the control mechanism of a light aircraft illustrates the proposed method. Full article

(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics 2022)

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