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Publications - 6525

Modeling the Stiffening Behavior of Sand Subjected to Dynamic Loading

Majd Ahmad Richard Ray

Publication Name: Geosciences Switzerland

Publication Date: 2024-01-01

Volume: 14

Issue: 1

Page Range: Unknown

Description:

In geotechnical engineering, dynamic soil models are used to predict soil behavior under different loading conditions. This is crucial for many dynamic geotechnical problems related to earthquakes, train loading and machine foundation design. Researchers agree that under dry or drained conditions, cohesionless soils increase in stiffness with each loading cycle. Soil models that simulate the dynamic behaviors of soils are often coupled with the Masing criteria. Such models neglect the impact of stiffening during cyclic loading, leading to an underestimation in the shear modulus (G). This study investigates the stiffening behavior by conducting laboratory tests on three types of Danube sands using the Resonant Column-Torsional Simple Shear device (RC-TOSS). The increase in the dynamic shear modulus with an increasing number of cycles is substantial, especially for samples with low density. Sometimes, the dynamic shear modulus doubles when loaded at high stress levels for more than 50 cycles. A new model is introduced to simulate the stiffening behavior of dry sand when subjected to cyclic torsional loading. Modifications are proposed for the Ramberg–Osgood and Hardin–Drnevich models and for the Masing criteria to overcome the limitations that accompany these models due to the influence of stiffening caused by repetitive loading being ignored. This model can be implemented in finite element and finite difference software to solve dynamic geotechnical problems.

Open Access: Yes

DOI: 10.3390/geosciences14010026

Environmental Sustainability and the First Demographic Dividend. The Case of Four Eastern African Countries

Seyoum Teffera Mengesha Éva Berde

Publication Name: Chemical Engineering Transactions

Publication Date: 2023-01-01

Volume: 107

Issue: Unknown

Page Range: 133-138

Description:

Sub-Saharan Africa faces immense challenges in spurring economic development and alleviating poverty, while these countries also should protect the environment amid population growth and industrial development. This study analyses the interrelationships between demographic change, economic growth, and pollution in four East African countries – Ethiopia, Kenya, Sudan, and Uganda – from 1990-2019. Using panel data and econometric analysis, the paper examines whether declining fertility rates and parallel diminishing of the youth dependency burdens are associated with accelerated growth and rising emissions. The results affirm that falling fertility has opened a window of opportunity through the ‘first demographic dividend’, which can catalyse growth by increased shares of working-age individuals. However, this growth has been accompanied by rising carbon dioxide emissions, underscoring potential trade-offs between environmental and economic objectives. The findings highlight the importance of complementary health, education, governance, and sustainable production investments for countries to leverage their demographic dividends for inclusive and green growth. Successfully doing so will be vital to achieve multiple Sustainable Development Goals simultaneously.

Open Access: Yes

DOI: 10.3303/CET23107023

Knowledge management strategy as a chance of small and medium-sized enterprises

Andrea Bencsik Timea Juhasz

Publication Name: Organizational Culture and Behavior Concepts Methodologies Tools and Applications

Publication Date: 2017-02-10

Volume: 2-4

Issue: Unknown

Page Range: 577-607

Description:

This chapter shows how SMEs can compete with multinational companies. This chapter was written on the basis of practical research results. In this research, Hungarian and Slovakian SMEs were investigated from the view of a knowledge-based economy. The question was how they can face future challenges. The researchers wanted to know how SMEs handle their chance which is hidden in their way of thinking about a knowledge strategy. As a result, these companies seem to be afraid, uncertain, and think their success is only luck or a current incident. They live a "fly by night" existence, and they do not feel the importance of development, of studying, of knowledge, they run after work and money. These enterprises feel that they have to survive, and to this, they need money and financial capital. Therefore, knowledge and studying fall behind.

Open Access: Yes

DOI: 10.4018/978-1-5225-1913-3.ch028

Comparison of the A*-A and T φ-phi; Formulations for the 2-D analysis of solid-rotor induction machines

Miklós Kuczmann D. Marcsa

Publication Name: IEEE Transactions on Magnetics

Publication Date: 2009-09-01

Volume: 45

Issue: 9

Page Range: 3329-3333

Description:

We present two eddy-current field potential formulations to solve rotating electrical machine problems by applying the finite-element method (FEM) using the motional ${\mbi A}^{*}{-}{\mbi A}$-potential formulation and the motional ${\mbi T}, {\bf \Phi}{-}{\bf \Phi}$-potential formulation. We use the single-phase and three-phase solid-rotor induction motors of Problem No. 30a of TEAM Workshops to compare the potential formulations. We have solved both problems in the time domain and the frequency domain. © 2009 IEEE.

Open Access: Yes

DOI: 10.1109/TMAG.2009.2022328

Assessing logistics strategy issues under cognitive biases

Péter Földesi Eszter Sós

Publication Name: 2023 14th IEEE International Conference on Cognitive Infocommunications Coginfocom 2023

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 141-146

Description:

Cognitive biases often appear in the decision-making process of highly qualified managers of companies because of the drive for efficiency and the time pressure in operation. There are also long-term strategic decisions where there is no longer time pressure, and yet cognitive bias appears, for example during the selection between the Push and Pull systems in logistics. The description of the actual situation has to be quantified because communication between human-machine systems, as defined in cognitive info-communication, is only viable if cognitive biases in decision-making can be considered properly. We propose fuzzy approach and measures that can assess whether the production uses a Push or Pull logistics strategy for a specific product or for the entire company.

Open Access: Yes

DOI: 10.1109/CogInfoCom59411.2023.10397543

Non-simplex enclosing polytope generation concept for Tensor Product model transformation based controller design

Péter Galambos József Kuti Peter Baranyi

Publication Name: 2016 IEEE International Conference on Systems Man and Cybernetics Smc 2016 Conference Proceedings

Publication Date: 2017-02-06

Volume: Unknown

Issue: Unknown

Page Range: 3368-3373

Description:

In polytopic model-based controller synthesis, the vertices of the model determine the achievable performance characteristics. This paper introduces a new concept, that allows for the sophisticated construction of non-simplex enclosing polytopes. The non-simplex structures in general, have much better descriptor properties than the simplex one that leads to less conservative synthesis. The paper demonstrates the workflow of controller design for a nonlinear system through the example of the TORA (Translational Oscillator with a Rotational Actuator) system. The numerical results clearly show that the proposed approach is capable of excluding non-stabilizable regions located between the exact convex hull and the enclosing simplex. The non-simplex polytope leads to an increased number of vertices but it practically does not influence the viability of Tensor-Product (TP) formalization and the feasibility of controller design while the achievable control performance can be improved significantly.

Open Access: Yes

DOI: 10.1109/SMC.2016.7844754

Beyond wellness: modeling the impact of organizational physical activity climate on job performance through psychological and behavioral pathways

Ufuk Türen Güven Dere Lili Anna Hujber Selcan Ergun Syed Ibrahim Bilal Majid Vladimir Simic

Publication Name: Frontiers in Psychology

Publication Date: 2026-01-01

Volume: 17

Issue: Unknown

Page Range: Unknown

Description:

Introduction – This study introduces Organizational Physical Activity Climate (OPAC) as a domain-specific extension of organizational climate theory, addressing the limited understanding of how workplace environments influence employees’ physical activity (PA), job satisfaction (JS), and job performance (JP). While prior research has primarily focused on individual-level determinants, organizational-level influences and their indirect effects on PA, JS, and JP remain insufficiently explored. Methods – Data were collected from 543 respondents through field visits to 60 universities and academic conferences in Istanbul. Exploratory and confirmatory factor analyses were conducted using JAMOVI-R, and structural equation modeling was performed using SmartPLS. Results – OPAC did not have a significant direct effect on job performance. However, PA partially mediated the OPAC-job performance relationship, while JS fully mediated this relationship. The serial mediation pathway from OPAC to PA, JS, and JP was also supported, although the effect was modest. Discussion – The study contributes to the literature by introducing and validating OPAC as a domain-specific organizational climate construct and by suggesting that its association with JP is primarily reflected through indirect behavioral and psychological pathways. It also offers practical implications for organizations aiming to enhance employee well-being and performance through health-supportive workplace climates.

Open Access: Yes

DOI: 10.3389/fpsyg.2026.1817693

Structural entropy in detecting background patterns of AFM images

L. M. Molnár Imre Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 179-183

Description:

Structural entropy was developed for detecting the type of localization in charge distributions on a finite grid, especially in mesoscopic electronic systems. However, it is possible to detect and analyze superstructures, i.e., topologies consisting of more structures with different types of localization properties. In the definition of the structural entropy, the von Neumann entropy of the system is divided into two parts: first, the extension entropy, which is simply the logarithm of the occupation number; the second part is the structural entropy. On a structural entropy versus logarithm of the spatial filling factor map, the different types of localizations follow different, well-characterized curves. Spatial filling factor measures the percentage of the "filled" (i.e., high intensity) pixels of the image. An atomic force microscopy (AFM) image can be interpreted as some kind of charge distribution on a grid: after normalization, the darkness (or lightness) of the pixels fulfills all the necessary conditions. AFM image artifacts can be detected by plotting the structural entropy versus the logarithm of the spatial filling factor maps of the images. Not only the type of an added large-scale Gaussian, parabolic, exponential, or other function can be identified, but also by careful study of the curves belonging to the structures, the parameters can be detected, too. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.04.025

Comparing the aggregation capability of the MPT communications library and multipath TCP

Ákos Kovács

Publication Name: 7th IEEE International Conference on Cognitive Infocommunications Coginfocom 2016 Proceedings

Publication Date: 2017-01-03

Volume: Unknown

Issue: Unknown

Page Range: 157-161

Description:

The MPT network layer multipath communication library-which was proposed to be a possible new basis for the future cognitive info-communication-is capable to use multiple communication channels to create an UDP tunnel which uses GRE tunnel protocol. On the other hand, Multipath TCP uses a special kernel module which creates multiple TCP sub-flows to aggregate network throughput. In this paper we used twelve 100Mbps speed channels to compare the aggregation capabilities of these two multipath communication techniques. Different scenarios were used: we measured both IPv4 and IPv6 as underlying and encapsulation protocols. In all cases, we used one to twelve channels to measure the aggregation capabilities with the iperf network measurement tool and also with HTTP download.

Open Access: Yes

DOI: 10.1109/CogInfoCom.2016.7804542