A Numerical Approach on New Constitutive Model for Thixotropic Substances

2015 ◽  
Vol 751 ◽  
pp. 95-101
Author(s):  
Thales Augusto Barbosa Pinto Silva ◽  
Hilbeth Parente Azikri de Deus ◽  
Cezar Otaviano Ribeiro Negrão
Keyword(s):  
Constitutive Equation ◽  
Constitutive Model ◽  
Structural Evolution ◽  
Numerical Approach ◽  
Point Of View ◽  
Structural Level ◽  
Coupled Equations ◽  
Industrial Sectors ◽  
Jeffreys Model ◽  
Simulation Point

The thixotropic substances can be found in different industrial sectors, such as chemical, biomedical, manufacturing and oil. These substances show a rheological time-dependent behavior, dependent of their structural level. Generally, a constitutive model for the thixotropic substances is composed by a pair of coupled equations: the constitutive equation (based on viscoelastic models) and the rate equation (that describes the structural evolution). In many works presented in the specialized literature, the shear modulus and viscosity dependencies with the structural nature are not formally considered in the dynamical principles from that the constitutive equation is originated. In the present work, a new, thermodynamically consistent, constitutive model for thixotropic substances, where such dependences are considered, is presented and some rheological tests are analyzed in a numerical simulation point of view (code developed in MATLAB). The constitutive model is based on Jeffreys’ model and the coagulation theory of Smoluchowsky.

scholarly journals Infrastructure development in Africa’s regions: investment trends and challenges

2021 ◽  
Vol 295 ◽  
pp. 01029
Author(s):  
Alina Ibragimova ◽  
Yan Wang ◽  
Michail Ivanov
Keyword(s):  
Empirical Evidence ◽  
Production Function ◽  
Global Economy ◽  
Point Of View ◽  
Economic Downturn ◽  
Infrastructure Development ◽  
Social Infrastructure ◽  
Economic Point ◽  
Industrial Sectors

The purpose of this work is to provide information on the development of the infrastructure of the African economy. The study provides statistics on African regions and industries. This article focuses on the forms of economic and social infrastructure, and directs to determine the share development infrastructural in Africa. The Africa has entered an era of devastating change this study shows that with the unfolding economic downturn in the northern economies that have traditionally dominated the global economy. The article provides empirical evidence on how the industrial sectors developed from an economic point of view. The authors believe that infrastructure affects output and productivity directly as a contribution to the production function of other sectors and as part of GDP formation. The article discusses the development of infrastructure for the period 1999-2019 without more detailed dynamics. It also does not explain the main topics developed by the authors. The work provides knowledge on how investments are developing in Africa, how industries have developed, and what is the role of each infrastructure sector in this development. It also shows how different areas of infrastructure work with different successes in creating new paths in the African economy.

scholarly journals A Numerical Approach for Sound Quality of Vehicle Doors

2020 ◽  
Vol 25 (1) ◽  
pp. 9-16
Author(s):  
Erkut Yalçın ◽  
Halil Bilal ◽  
Ayhan Yağcı ◽  
Haluk Erol
Keyword(s):  
Sound Pressure ◽  
Sound Quality ◽  
Numerical Approach ◽  
Design Sensitivity ◽  
Point Of View ◽  
Vehicle Body ◽  
Fem Model ◽  
Body Development ◽  
Design Variables

A Vibro-Acoustic Finite Element Method (FEM) model capable of calculating the transient sound pressure generated by the door slam of a vehicle was developed in this study. A design sensitivity analysis (DSA) was performed for investigating the effects of major design variables on the related sound quality metrics. The methodology was developed using a sedan-car and its FEM model. This paper shows that a Computer Aided Engineering (CAE) model can be used as a rather powerful tool for giving design change decisions for the door components from sound quality point of view during vehicle body development according to psychoacoustic parameters.

Late Carboniferous Schlingen in the Gotthard nappe (Central Alps) and their relation to the Variscan evolution

2021 ◽  
Author(s):  
Mario Buehler ◽  
Roger Zurbriggen ◽  
Alfons Berger ◽  
Marco Herwegh ◽  
Daniela Rubatto
Keyword(s):  
Shear Zone ◽  
Country Rock ◽  
Structural Evolution ◽  
Point Of View ◽  
Swiss Alps ◽  
Low Grade ◽  
Central Alps ◽  
Structural Investigations ◽  
Alpine Belt ◽  
Main Cluster

<p>Many pre‐Mesozoic basements of the Alpine belt contain kilometre‐scaled folds with steeply inclined axial planes and fold axes. Those structures are referred to as Schlingen folds. They deform polymetamorphic gneisses, often Late‐Ordovician metagranitoids and are cross‐cut themselves by Permian intrusions. However, the structural evolution of such Schlingen is still not completely understood and their geodynamic significance for the Variscan evolution is not clear. To close this gap, this study investigates in detail a well-preserved Schlingen structure in the Gotthard nappe (Central Swiss Alps). This Schlingen fold evolved by a combination of shearing and folding under amphibolite facies conditions. Detailed digital field mapping coupled with petrological and structural investigations reveal local synkinematic migmatisation in the fold hinges parallel to axial planes. U‐Pb dating of zircons separated from associated leucosomes reveal cores that record a detrital country rock age of 450 ± 3 Ma, and rims with a range of dates from 270 to 330 Ma. The main cluster defines an age of 316 ± 4 Ma. We ascribe this Late‐Carboniferous age to peak metamorphic conditions of the late‐Variscan Schlingen phase.</p><p>The pre-Schlingen structures are subdivided into three older deformation events, which are connected to the Cenerian and post-Cenerian deformations. In addition, until now unknown, post Schlingen-, but pre-Alpine transpressional deformation have been detected and described. This superimposed deformation produced locally a low-grade foliation and minor undulation of the Schlingen structures.</p><p>The detail data of the investigated fold structures are linked with already described Schlingen folds in the wider Alpine realm, which all are concentrated in the most southern parts of the Variscides. From a geodynamic point of view and based on the new tectono-metamorphic constraints, we propose Schlingen formation preceded and concurred the crustal-scale transpressional tectonics of the East Variscan Shear Zone. This scenario separates, at least in a structural sense, the Southern Variscides from more northern parts (also Gondwana derived) inside Pangea, where Schlingen folds are absent.</p>

Entropy of Nanostructures

2017 ◽  
pp. 600-614
Author(s):  
Ottorino Ori ◽  
Franco Cataldo ◽  
Mihai V. Putz
Keyword(s):  
Mechanical Properties ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
Defect Formation ◽  
Vacancy Concentration ◽  
Structural Evolution ◽  
Point Of View ◽  
Structural Defects ◽  
Formation Mechanisms ◽  
Topological Invariants

Recent advances in graphene studies deal with the influence of structural defects on graphene chemical, electrical, magnetic and mechanical properties. Here the complex mechanisms leading to the formation of clusters of vacancies in 2D honeycomb HD lattices are described by a pure topological point of view, aiming to correlate the variation of specific topological invariants, sensible to vacancy concentration, to the structural evolution of the defective networks driven by the topo-thermodynamical Gibbs free energy. Interesting predictions on defect formation mechanisms add details on the topological mechanisms featured by the graphenic structures with defects. Future roles of bondonic particles in defective HD materials are also envisaged.

scholarly journals The Role of Operating Income on the Internal Long-Term Financing Decisions

2020 ◽  
Vol 9 (4) ◽  
pp. 1
Author(s):  
Hisham I. Ahmaro ◽  
Abdul Khaliq M. Alrawi
Keyword(s):  
Point Of View ◽  
Financial Reports ◽  
Operating Income ◽  
Financial Decisions ◽  
Financing Decisions ◽  
Industrial Companies ◽  
Industrial Sectors ◽  
High Investment ◽  
Internal Financing

This paper aims to demonstrate the roles and importance of the operating income of the management of Jordanian industrial companies, and the extent to which they depend on it to make the necessary financial decisions in order to meet their long-term needs. The data was collected from the financial reports of companies representing the study community for the period 2012-2016, after being classified by different industrial sectors. The research employed the operating incomes as an independent variable and long-term internal financial decisions as a dependent variable. The results of the data analysis showed a disparity between the different industrial sectors. The Engineering and Construction industries achieved the highest average of the ratio of long-term internal financing by 0.986, due to the importance of this activity on the Jordanian economy and the size of the high investment in it from the researchers' point of view. The lowest average was shown in the Paper and Cardboard sector by 0.550, due to the lack of investments in it compared to other industrial sectors that are more important to the Jordanian economy. The overall annual average of long-term domestic financing for all sectors was 0.892. The results also showed a statistically significant role for operating income in long-term internal financial decisions by the management of Jordan's public industrial joint stock companies.

scholarly journals Study on Dynamic Constitutive Model of Weakly Consolidated Soft Rock in Western China

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Lei Wang ◽  
Hongming Su ◽  
Yue Qin ◽  
Shiguan Chen
Keyword(s):  
Constitutive Equation ◽  
Constitutive Model ◽  
Split Hopkinson Pressure Bar ◽  
Soft Rock ◽  
Frozen Soil ◽  
Constitutive Relationship ◽  
Western China ◽  
Parameter Determination ◽  
Engineering Practice ◽  
The Impact

To obtain the impact mechanical response and establish the dynamic damage constitutive relationship of frozen sandstone at low temperature conditions, the impact test of Cretaceous red sandstone under different temperatures was conducted using a split Hopkinson pressure bar (SHPB) device. According to the characteristics of the stress-strain curves obtained by the test, a constitutive model considering the damage effect, temperature effect, and strain rate effect was established, which was improved by Zhu–Wang–Tang (Z–W–T) constitutive model. It was proved that the fitting curves of constitutive equation were in good agreement with the test curves. The fluctuation amplitude of fitting error was controlled within ±4 MPa. The physical meaning of each parameter of the constitutive model is clear, and most of them are fixed values. The selection range of variable parameters and the related change rules are confirmed, which improves the practicability of constitutive model. The constitutive equation can well describe the nonlinear features of this kind of frozen sandstone under impact loading. It was also found that the constitutive equation was applicable to express the dynamic mechanical properties of rock-like materials such as hard rock, soft rock, frozen soil, raw coal, and concrete. It can be referred to the parameter determination method in this paper to study and determine the parameters, reduce the difficulty of parameter selection, and improve the practicability of the constitutive model and parameters, so as to guide the engineering practice better.

Algorithms for the calculation of X-ray diffraction patterns from finite element data

2010 ◽  
Vol 43 (6) ◽  
pp. 1287-1299 ◽  
Author(s):  
E. Wintersberger ◽  
D. Kriegner ◽  
N. Hrauda ◽  
J. Stangl ◽  
G. Bauer
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Point Of View ◽  
X Ray Diffraction ◽  
Displacement Fields ◽  
X Ray ◽  
Si Substrates ◽  
Diffraction Patterns ◽  
Simulation Point ◽  
Ccd Detectors

A set of algorithms is presented for the calculation of X-ray diffraction patterns from strained nanostructures. Their development was triggered by novel developments in the recording of scattered intensity distributions as well as in simulation practice. The increasing use of two-dimensional CCD detectors in X-ray diffraction experiments, with which three-dimensional reciprocal-space maps can be recorded in a reasonably short time, requires efficient simulation programs to compute one-, two- and three-dimensional intensity distributions. From the simulation point of view, the finite element method (FEM) has become the standard tool for calculation of the strain and displacement fields in nanostructures. Therefore, X-ray diffraction simulation programs must be able to handle FEM data properly. The algorithms presented here make use of the deformation fields calculated on a mesh, which are directly imported into the calculation of diffraction patterns. To demonstrate the application of the developed algorithms, they were applied to several examples such as diffraction data from a dislocated quantum dot, from a periodic array of dislocations in a PbSe epilayer grown on a PbTe pseudosubstrate, and from ripple structures at the surface of SiGe layers deposited on miscut Si substrates.

Coupled forms of the differential equations governing radio propagation in the ionosphere

1954 ◽  
Vol 50 (2) ◽  
pp. 319-333 ◽  
Author(s):  
P. C. Clemmow ◽  
J. Heading
Keyword(s):  
Magnetic Field ◽  
Differential Equations ◽  
Point Of View ◽  
Successive Approximations ◽  
Horizontal Magnetic Field ◽  
First Order ◽  
Coupled Equations ◽  
Oblique Propagation ◽  
Special Cases ◽  
Magnetic Meridian

ABSTRACTIt is shown that the equations governing oblique propagation in a horizontally stratified ionosphere with an oblique magnetic field can be cast into a form suitable for solution by successive approximations. In the general case this ‘coupled’ form consists of four first order differential equations, each being associated with one characteristic wave. In the special cases (a) horizontal magnetic field, (b) plane of incidence perpendicular to the magnetic meridian, two second order coupled equations of a particular type can be derived, each of which is associated with a pair of corresponding upgoing and downgoing characteristic waves. These latter equations are similar to, and include, those already given by Försterling(7) for vertical incidence.The cases in which there is no coupling are briefly considered from the point of view of the first order equations.The general formulation provides a basis for assessing the validity of the standard ‘ray’ approximation, alternative to that developed by Booker (2), and brings out the nature of its breakdown in coupling and reflexion regions.Specific applications and extensions of the theory are left for later consideration.

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