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Found 6327 publications

Effect of Rolling Resistance Model Parameters on 3D DEM Modeling of Coarse Sand Direct Shear Test

Majid Movahedi Rad M. Amine Benmebarek

Publication Name: Materials

Publication Date: 2023-03-01

Volume: 16

Issue: 5

Page Range: Unknown

Description:

This paper deals with the micro and macro behaviors of coarse sand inside a direct shear box during a geotechnical test. A 3D discrete element method (DEM) model of the direct shear of sand was performed using sphere particles to explore the ability of the rolling resistance linear contact model to reproduce this commonly used test considering real-size particles. The focus was on the effect of the interaction of the main contact model parameters and particle size on maximum shear stress, residual shear stress, and sand volume change. The performed model was calibrated and validated with experimental data and followed by sensitive analyses. It is shown that the stress path can be reproduced appropriately. For a high coefficient of friction, the peak shear stress and volume change during the shearing process were mainly affected by increasing the rolling resistance coefficient. However, for a low coefficient of friction, shear stress and volume change were marginally affected by the rolling resistance coefficient. As expected, varying the friction and rolling resistance coefficients was found to have less influence on the residual shear stress.

Open Access: Yes

DOI: 10.3390/ma16052077

The Political Elite's Thematic Framing of China in Recent Central European Elections

László Csicsmann Jan Hornat Joanna Starzyk-Sulejewska

Publication Name: Issues and Studies

Publication Date: 2023-03-01

Volume: 59

Issue: 1

Page Range: Unknown

Description:

China is geographically distant from Central European states, but cultural, economic and political exchanges between the regions are increasing. As such, the perception of China in these societies is susceptible to frames and narratives that are either instrumentally or organically created by local political elites. This paper aims to scrutinize the narratives and frames employed in the Czech Republic, Hungary and Poland during their most recent election cycles. It identifies five basic types of frames employed in the selected countries: sovereignty, opportunity, the balance of trade, debt-traps and human rights. This paper then concludes by evaluating these thematic frames and summarizes the key similarities in public discourses concerning relations with China.

Open Access: Yes

DOI: 10.1142/S1013251123500029

High-Nitrate-Supply-Induced Transcriptional Upregulation of Ascorbic Acid Biosynthetic and Recycling Pathways in Cucumber

Erzsébet Kiss-Bába Anita Szegő István Papp Iman Mirmazloum Márta Gyöngyik Neda Hesari Henriett Kolozs Dominika Vasas Zsolt Pónya

Publication Name: Plants

Publication Date: 2023-03-01

Volume: 12

Issue: 6

Page Range: Unknown

Description:

Nowadays open field and protected vegetable cultivation practices require and use genotypes which are precisely tailored to their intended growth environments. Variability of this kind provides a rich source of material to uncover molecular mechanisms supporting the necessarily divergent physiological traits. In this study, typical field-optimized and glasshouse-cultivated cucumber F1 hybrids were investigated, and displayed slower growth (‘Joker’) and faster growth (‘Oitol’) in seedlings. Antioxidant capacity was lower in ‘Joker’ and higher in ‘Oitol’, pointing to a potential redox regulation of growth. The growth response of seedlings to paraquat treatment indicated stronger oxidative stress tolerance in the fast-growing ‘Oitol’. To test whether protection against nitrate-induced oxidative stress was also different, fertigation with increasing potassium nitrate content was applied. This treatment did not change growth but decreased the antioxidant capacities of both hybrids. Bioluminescence emission revealed stronger lipid peroxidation triggered by high nitrate fertigation in the leaves of ‘Joker’ seedlings. To explore the background of the more effective antioxidant protection of ‘Oitol’, levels of ascorbic acid (AsA), as well as transcriptional regulation of relevant genes of the Smirnoff–Wheeler biosynthetic pathway and ascorbate recycling, were investigated. Genes related to AsA biosynthesis were strongly upregulated at an elevated nitrate supply in ‘Oitol’ leaves only, but this was only reflected in a small increase in total AsA content. High nitrate provision also triggered expression of ascorbate–glutathion cycle genes with stronger or exclusive induction in ‘Oitol’. AsA/dehydro–ascorbate ratios were higher in ‘Oitol’ for all treatments, with a more pronounced difference at high nitrate levels. Despite strong transcriptional upregulation of ascorbate peroxidase genes (APX) in ‘Oitol’, APX activity only increased significantly in ‘Joker’. This suggests potential inhibition of APX enzyme activity specifically in ‘Oitol’ at a high nitrate supply. Our results uncover an unexpected variability in redox stress management in cucumbers, including nitrate inducibility of AsA biosynthetic and recycling pathways in certain genotypes. Possible connections between AsA biosynthesis, recycling and nitro-oxidative stress protection are discussed. Cucumber hybrids emerge as an excellent model system for studying the regulation of AsA metabolism and the roles of AsA in growth and stress tolerance.

Open Access: Yes

DOI: 10.3390/plants12061292

Contribution to the knowledge of Rotundabaloghia mites: new species and new records (Acari: Mesostigmata: Rotundabaloghiidae) from the Oriental and Australasian regions

Sergey G. Ermilov Jenő Kontschán

Publication Name: Systematic and Applied Acarology

Publication Date: 2023-03-01

Volume: 28

Issue: 3

Page Range: 405-410

Description:

No description provided

Open Access: Yes

DOI: 10.11158/saa.28.3.1

Exactly Solvable Quadratic Differential Equation Systems Through Generalized Inversion

Ádám Bácsi Tihamér A. Kocsis

Publication Name: Qualitative Theory of Dynamical Systems

Publication Date: 2023-03-01

Volume: 22

Issue: 1

Page Range: Unknown

Description:

We study the autonomous systems of quadratic differential equations of the form x˙i(t)=x(t)TAix(t)+viTx(t) with x(t) = (x1(t) , x2(t) , … , xi(t) , ⋯) which, in general, cannot be solved exactly. In the present paper, we introduce a subclass of analytically solvable quadratic systems, whose solution is realized through a multi-dimensional generalization of the inversion which transforms a quadratic system into a linear one. We provide a constructive algorithm which, on one hand, decides whether the system of differential equations is analytically solvable with the inversion transformation and, on the other hand, provides the solution. The presented results apply for arbitrary, finite number of variables.

Open Access: Yes

DOI: 10.1007/s12346-023-00738-7

Numerical Investigation of Pre-Stressed Reinforced Concrete Railway Sleeper for High-Speed Application

Szabolcs Fischer Zoltán Major Szabolcs Szalai Mykola Sysyn Attila Németh Dmytro Kurhan Dóra Harangozó Majid Movahedi Rad Sarah Khaleel Ibrahim Dániel Harrach Szabolcs Kocsis Szurke Gusztáv Baranyai Géza Herczeg László Gáspár

Publication Name: Infrastructures

Publication Date: 2023-03-01

Volume: 8

Issue: 3

Page Range: Unknown

Description:

The current paper deals with the numerical investigation of a unique designed pre-stressed reinforced concrete railway sleeper for the design speed of 300 km/h, as well as an axle load of 180 kN. The authors applied different methodologies in their research: traditional hand-made calculations and two types of finite element software. The latter were AxisVM and ABAQUS, respectively. During the calculations, the prestressing loss was not considered. The results from the three methods were compared with each other. The hand-made calculations and the finite element modeling executed by AxisVM software are adequate for determining the mechanical inner forces of the sleeper; however, ABAQUS is appropriate for consideration of enhanced and sophisticated material models, as well as the stress-state of the elements, i.e., concrete, pre-stressed tendons, etc. The authors certified the applicability of these methodologies for performing the dimensioning and design of reinforced concrete railway sleepers with pre-stressing technology. The research team would like to continue their research in an improved manner, taking into consideration real laboratory tests and validating the results from FE modeling, special material models that allow calculation of crackings and their effects in the concrete, and so that the real pattern of the crackings can be measured by GOM Digital Image Correlation (DIC) technology, etc.

Open Access: Yes

DOI: 10.3390/infrastructures8030041

Bifurcations of the limit directions in extended Filippov systems

Mate Antali

Publication Name: Physica D Nonlinear Phenomena

Publication Date: 2023-03-01

Volume: 445

Issue: Unknown

Page Range: Unknown

Description:

This paper explores special bifurcations that appear in dynamical systems possessing codimension-2 discontinuity sets in the state space. In these systems, the vector field has continuously many directional limits at the discontinuity set. It is shown that the trajectories can reach the discontinuity set along specific limit directions. The number and type of these organising objects characterise the behaviour of the dynamics in the vicinity of the discontinuity set. Thus, bifurcations of limit directions have a remarkable effect on the system. In the paper, two special bifurcations are explored; the tangency bifurcation and the saddle–node bifurcation of limit direction are followed through different formulations of the dynamical system. It is demonstrated that these bifurcations appear in rigid body dynamics in the presence of dry friction.

Open Access: Yes

DOI: 10.1016/j.physd.2022.133622

Systems Engineering Based Sustainability Improvement in Automotive Product Development

Péter Németh Tamás Kolossváry Péter Németh

Publication Name: Journal of Engineering Management and Systems Engineering

Publication Date: 2023-03-01

Volume: 2

Issue: 1

Page Range: 53-60

Description:

Affected by new trends, automobile companies have altered stakeholder requirements on their main product-the automobile. With enactment of new regulations concerning sustainability, new features appeared quickly, such as electrification, sharing services, autonomous mobility and so on. In this study, we present sustainability as a stakeholder and analyze the method of its realization in Systems Engineering (SE) based product development. Formula SAE provides a validated setting to conduct experiments on integrating sustainability into the classical product requirement architectures. By taking into consideration the use of SE or adding other methodological frameworks, findings can establish a new setting in sustainability research. The results of this study may be enlightening for scholars and practitioners and calls for further research on embedding sustainability requirements in automotive product development by using SE.

Open Access: Yes

DOI: 10.56578/jemse020103

On Selecting, Ranking, and Quantifying Features for Building a Liver CT Diagnosis Aiding Computational Intelligence Method

Ferenc Lilik Melinda Kovacs Szilvia Nagy

Publication Name: Applied Sciences Switzerland

Publication Date: 2023-03-01

Volume: 13

Issue: 6

Page Range: Unknown

Description:

Featured Application: The selected attributes and their ranking and weights can be used in decision support algorithms in computer aided diagnosis. The liver is one of the most common locations for incidental findings during abdominal CT scans. There are multiple types of disease that can arise within the liver and many of them are nodular. The ultimate goal of our research is to develop an expert knowledge-based system using fuzzy signatures, to support decisions during diagnosis of the most frequent of these nodular lesions. Since the literature contains limited information about the graphical properties of CT images that must be taken into consideration and their relationship to one another, in this paper we focused on selecting and ranking the input parameters using expert knowledge and determining their importance. Six visual attributes of lesions (size, shape, density, homogeneity contour, and other features) were selected based on textbooks of radiology and expert opinion. The importance of these attributes was ranked by radiologist experts using questionnaires and a pairwise comparison technique. The most important feature was found to be the density of the lesion on the various CT phases, and the least important was the size, the order of the other attributes was other features, contour, homogeneity, and shape, with a Kendall concordance coefficient of 0.612. Weights for the attributes, to be used in the future fuzzy signatures, were also determined. As a last step, several statistical parameter-based quantities were generated to represent the above abstract attributes and evaluated by comparing them to expert opinions.

Open Access: Yes

DOI: 10.3390/app13063462