Theoretical Model
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2021 ◽  
Vol 29 (6) ◽  
pp. 0-0

Empirical work on the environmental effects of FDI has produced a mixed bag of results, with hardly any evidence for Middle East and North Africa (MENA) countries. A theoretical model is presented, postulating that whether FDI has a positive or negative effect on the environment depends on the position of the underlying country or region on the environmental Kuznets curve (EKC). The empirical results indicate that FDI leads to environmental degradation in MENA countries and that they fall on the rising sector of the EKC. The theoretical model is supported by the empirical results.


2021 ◽  
Author(s):  
BingBing Wang ◽  
HaiKuan Chen ◽  
GuangTao Xu ◽  
JianWei Zhang ◽  
MingHao Zhao

Abstract Shot peening is widely used in engineering as a classical strengthening process. Although many studies on shot peening have been done, most have focused on homogeneous target materials. In this paper, a theoretical model is proposed for predicting the surface morphology of inhomogeneous target materials. The topography of target materials after single-shot impact is calculated on the basis of energy conservation and Hertz contact theory, and the final three-dimensional surface topography after multiple-shot impact is obtained through superposition. Single-shot and random multiple-shot finite element models are used to show the advantages of the proposed model over the existing theoretical model for homogeneous target materials. The roughness is found to increase with the shot velocity and shot radius.


PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0259002
Author(s):  
Pedro Patrício ◽  
Nuno A. M. Araújo

We consider a simple theoretical model to investigate the impact of inheritances on the wealth distribution. Wealth is described as a finite resource, which remains constant over different generations and is divided equally among offspring. All other sources of wealth are neglected. We consider different societies characterized by a different offspring probability distribution. We find that, if the population remains constant, the society reaches a stationary wealth distribution. We show that inequality emerges every time the number of children per family is not always the same. For realistic offspring distributions from developed countries, the model predicts a Gini coefficient of G ≈ 0.3. If we divide the society into wealth classes and set the probability of getting married to depend on the distance between classes, the stationary wealth distribution crosses over from an exponential to a power-law regime as the number of wealth classes and the level of class distinction increase.


Author(s):  
Bartolomé Vázquez-Bernal ◽  
Roque Jiménez-Pérez

AbstractThe objective of this work was the theoretical modeling of a construct based on teaching practice about the perception that pupils have of difficulties in problem solving (PS) in experimental sciences, specifically physics, to predict pupil performance in PS. The research was carried out with an incidental sample of second year of secondary education pupils, of 13 to 14 years in age. The pupils and their teachers were involved in a project in which PS, classroom inquiry, and Hooke’s law were considered to be central. The information collection instrument was a Likert type questionnaire to investigate the various difficulties perceived by the pupils (Knowledge, Trust, Path, Interest,…) in the problem-solving processes applying Hooke’s law. A theoretical model was estimated and not rejected that involved only one factor (a PS factor), with all of its variables strongly interrelated and a set of constraints represented by covariances between theoretical hidden variables. This model is a starting point from which to understand how pupils at this level perceive PS in experimental sciences.


Author(s):  
Valeriy V. Kirilovskiy ◽  
Yuri V. Belousov

Bearing units of lifting machines, products of construction, road, aviation, space and other branches of technology are very important structural elements, since the failure of even one bearing can cause the failure of the entire product. The results of experimental verification of the theoretical model of bearing operation under combined loading conditions are presented. The behavior under load of bearing units in the most general case can be represented by a sequence of five design schemes, expressed in the form of five statically indeterminate beams. The purpose of the experiments was to test this model under real loading conditions. The experiments were based on the analysis of the geometric shape of the curved elastic line, which the shaft of the bearing assembly acquires under load. The experimental results confirmed the validity of the model and showed that the previously generally accepted model of a two-support beam is not implemented. The conclusion is confirmed that in responsible lifting machines, as well as in responsible products of construction, road, aviation, space and other branches of technology, it is impractical to calculate bearings according to the traditional method, since an erroneous value of bearing durability can be obtained, overestimated from 28.37 to 26.663.9 times.


Author(s):  
Diana Faviola Olea-Flores ◽  
Alejandra Aldrette-Malacara ◽  
Luis Cuautle-Gutiérrez

The multivariate technique of partial least squares structural equations (PLS-SEM) considered as second generation, has become more relevant in its application in recent years in various investigations, so this article considers an descriptive research, the which presents some properties characteristic of said technique and through the application of data and values obtained from a case study shows the phases required to validate and evaluate a model with the PLS-SEM technique. With the results obtained, a theoretical model is generated and proposed that could be useful for researchers who starting in the use and application of this technique.


2021 ◽  
pp. 101269022110439
Author(s):  
Ulrik Wagner ◽  
Rasmus K. Storm

Sport scandals have attracted significant interest within and beyond the sociology of sport. However, developing a theoretical understanding of sport scandals has so far been neglected. Therefore, the two-fold purpose of this conceptual paper is to outline a theoretical model for understanding the form of a sport scandal, and to construct two typical sport scandals that can assist us in theorizing and differentiating how sport scandals may have varying effects on society. In our work, we rely on insights on form formulated by the German sociologist Niklas Luhmann combined with notions of ideal types derived from Max Weber. Accordingly, scandals are described as examples of paradoxical forms where excluded meaning re-enters to create spaces of temporary liminality. Despite their common characteristics, we are able to construct two ideal types of scandals – bureaucratic fallacy and charismatic failure – to understand why scandals may have varying impacts on the environment.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Vanessa Bueno-Sancho ◽  
Elizabeth S. Orton ◽  
Morgan Gerrity ◽  
Clare M. Lewis ◽  
Phoebe Davey ◽  
...  

AbstractFungi have evolved an array of spore discharge and dispersal processes. Here, we developed a theoretical model that explains the ejection mechanics of aeciospore liberation in the stem rust pathogen Puccinia graminis. Aeciospores are released from cluster cups formed on its Berberis host, spreading early-season inoculum into neighboring small-grain crops. Our model illustrates that during dew or rainfall, changes in aeciospore turgidity exerts substantial force on neighboring aeciospores in cluster cups whilst gaps between spores become perfused with water. This perfusion coats aeciospores with a lubrication film that facilitates expulsion, with single aeciospores reaching speeds of 0.053 to 0.754 m·s−1. We also used aeciospore source strength estimates to simulate the aeciospore dispersal gradient and incorporated this into a publicly available web interface. This aids farmers and legislators to assess current local risk of dispersal and facilitates development of sophisticated epidemiological models to potentially curtail stem rust epidemics originating on Berberis.


Author(s):  
Julio Alcantara

The study of plant community dynamics has a long tradition. However, this field has barely incorporated the tools developed in the modern study of ecological networks. Key for this incorporation is the availability of a theoretical model able to incorporate field data about plant-plant interactions. In this study I introduce the Recruitment and Replacement (R&R) model that explicitly incorporates empirical networks of plant-plant interactions that occur during recruitment. The R&R model is built on fundamental demographic rates and incorporates competition for space between adults, intra- and inter-specific effects of established plants on recruitment and the colonization of vacant space. The basic analysis of the model provides predictions regarding different aspects of plant community dynamics, like the environmental conditions and species properties under which facilitation of recruitment is more likely to occur, the effect of recruitment facilitation on invasion, the effects of plant-plant interactions on equilibrium abundances and community stability, and the network properties that should relate to species equilibrium abundances. Many of these predictions agree with findings from published meta-analyses, supporting the general validity of the recruitment networks framework as a general approach to integrate the study of plant community dynamics into the study of ecological networks.


2021 ◽  
Author(s):  
Ulzhamilya Bibatyrovna Serikbayeva

In the modern world, the rapid growth of science and technology has caused a huge need for information exchange. There was a need to create a theoretical model of the translation process. Translation problems attracted the attention of linguists, and the study of translation began to take shape as a special linguistic discipline. The requirements for translation accuracy have significantly increased. The translation was supposed to ensure the accurate transmission of information in all details. Without allowing at the same time violations of the norms of the translation language. A strictly scientific analysis of the semantic functions of comparable forms of languages involved in the translation process was required. It was necessary to find out what the linguistic essence of this process is, to what extent it is determined by linguistic factors proper, to what extent such factors limit the accuracy of information transmission.


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