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Determination of Natural Frequencies with Acoustic Methods and their Relation to Residual Stress

Zoltán Weltsch Alexandra Kiri

Publication Name: Advances in Science and Technology

Publication Date: 2025-01-01

Volume: 165 AST

Issue: Unknown

Page Range: 199-204

Description:

There are number of different methods and procedures in vibration analysis, where the natural frequencies of the specimen or the system are one of the key parameters. It is known that these frequencies can change under load, for example in response to pre-stressing, but the effect of residual stresses is less known. By developing a suitable method, natural frequencies can be used to predetermine residual stress, therefore this method can be used for example predicting whether it will cause deformation during machining of a part, whether it requires increased attention or how to set the parameters well for vibratory stress relief. The results can be significant cost and time savings, as well as the improvements of the quality. Natural frequency is the frequency of free vibration of an undamped linear vibration system, or in other words at which a system left alone will vibrate after excited by an external force [1]. Metal castings or welded structures may have several natural frequencies which appear as frequency bands or ranges on the measurement images. Based on these, to determine the natural frequency of a component or system, we need to excite a frequency as close as possible to the natural frequency for the resonance to occur. When the resonance is reached, the amplitude of the system is at its maximum, and the natural frequencies of the workpiece can be measured. Traditionally, sensors, usually accelerometers are used to measure the natural frequency. The continuous development of information technology has made it possible to replace these sensors with an acoustic diagnostic system. During this research, we have developed an acoustic diagnostic system and procedure, which can generate the acoustic measurement images. We have evaluated the measurement images in many ways, and many different types of components and materials (mostly iron alloys) were analyzed. In addition, the changes of natural frequencies show a similar pattern in the case of parts before treating with vibratory stress relief as for load tests.

Open Access: Yes

DOI: 10.4028/p-e4cRIL

Counterhegemony: Radical Economics and the Appeal of State Socialism in Cold War Era Nigeria (1946–1990)

Adam Mayer

Publication Name: International Journal of African Historical Studies

Publication Date: 2021-01-01

Volume: 54

Issue: 3

Page Range: 377-397

Description:

Normative state socialist economic theory appeared in the mid-1920s with Soviet economist Preobrazhensky. In Nigeria, many economic thinkers were influenced by Soviet and other Eastern European economic theory during the Cold War years. Bala Usman and Segun Osoba focused on the destruction of feudal land law and on delinking from the capitalist world economy; Bade Onimode and Ola Oni on emulating state socialist Eastern European economic theory and practice in an effort to overcome structural underdevelopment; Claude Ake in his Marxist phase made use of the Hungarian economist Tamás Szentes’s heterodox socialist development theory that the latter developed while the two were colleagues at the University of Dar-es-Salaam in Tanzania. Nigeria’s oil incomes were to be used in all these plans to kick-start heavy industry in the country. As the USSR’s alternative globalization path disappeared and then the Nigerian compradores’ share of profits grew by the early 21st century, interest in these radical classics reappeared in Nigeria.

Open Access: Yes

DOI: DOI not available

Pedigree-Based Description of Danubia Alba Rabbit Breed Lines

János Posta Zsolt Gerencsér Zsolt Matics Zoltán Német Csongor Demeter Máté Sándor

Publication Name: Animals

Publication Date: 2024-09-01

Volume: 14

Issue: 18

Page Range: Unknown

Description:

The diversity of livestock animal breeds is an integral part of global biodiversity and requires careful management for sustainability and future availability. Avoiding inbreeding is a crucial aspect of mating of breeding animals. Our aims were to describe the quality of the pedigree, generation interval, gene origin, inbreeding, and effective population size of Danubia Alba rabbit lines. Line “D” is the maternal, whereas lines “C” and “X” are used as the paternal lines. The pedigree information was followed back from the actual breeding rabbits up to the founder animals. The rabbits having offspring in 2023 were chosen as reference populations for each line. The complete generation equivalent (GenCom) was 17.68 for line “C”, 18.32 for line “D”, and 17.49 for line “X”, respectively. The maximum number of generations (GenMax) was above 30 for each line. The estimated bottleneck effect is mostly the result of selection and not a real genetic loss. The Wright inbreeding coefficient (F_Wright) was the highest for the “X” line rabbits, whereas it was the lowest for the line “D”. Kalinowski’s decomposition of inbreeding showed that it originated mostly from the past; the current fixation of alleles was quite similar for the line “C” and “D”. Based on the predicted effective population sizes, it seems that there is no problem in maintaining of Danubia Alba lines.

Open Access: Yes

DOI: 10.3390/ani14182740

Enhancing Autonomous Navigation: Real-Time LIDAR Detection of Roads and Sidewalks in ROS 2 †

Erno Horváth Miklos Unger Barham Jeries Barham Farraj Abdelrahman Alabdallah

Publication Name: Engineering Proceedings

Publication Date: 2025-01-01

Volume: 113

Issue: 1

Page Range: Unknown

Description:

Autonomous navigation in urban environments demands robust real-time detection of drivable surfaces despite high-throughput LIDAR data. While majority of current approaches often rely on camera-based or multi-sensor fusion systems, this paper introduces an enhancement of our previous LIDAR-centric solution integrated within the Robot Operating System 2 (ROS 2) framework to address computational efficiency and precision challenges. We propose a parallelized algorithm suite for LIDAR-based road and sidewalk detection, achieving processing rates exceeding 20 Hz. Validation on the KITTI benchmark and own datasets demonstrates improved accuracy in complex urban scenarios compared to traditional ground-filtering techniques. To foster reproducibility, the ROS 2-compliant implementation, datasets, and evaluation scripts are publicly released. This work underscores the potential of LIDAR sensors coupled with modern robotic frameworks to enhance perception pipelines in autonomous systems.

Open Access: Yes

DOI: 10.3390/engproc2025113024

Contribution of ankle motion pattern during landing to reduce the knee-related injury risk

Yaodong Gu Julien S. Baker Gusztáv Fekete Justin Fernandez Xin Ma Meizi Wang Datao Xu Huiyu Zhou Teo Ee Chon

Publication Name: Computers in Biology and Medicine

Publication Date: 2024-09-01

Volume: 180

Issue: Unknown

Page Range: Unknown

Description:

Background: Single-leg landing (SL) is an essential technique in sports such as basketball, soccer, and volleyball, which is often associated with a high risk of knee-related injury. The ankle motion pattern plays a crucial role in absorbing the load shocks during SL, but the effect on the knee joint is not yet clear. This work aims to explore the effects of different ankle plantarflexion angles during SL on the risk of knee-related injury. Methods: Thirty healthy male subjects were recruited to perform SL biomechanics tests, and one standard subject was selected to develop the finite element model of foot-ankle-knee integration. The joint impact force was used to evaluate the impact loads on the knee at various landing angles. The internal load forces (musculoskeletal modeling) and stress (finite element analysis) around the knee joint were simulated and calculated to evaluate the risk of knee-related injury during SL. To more realistically revert and simulate the anterior cruciate ligament (ACL) injury mechanics, we developed a knee musculoskeletal model that reverts the ACL ligament to a nonlinear short-term viscoelastic mechanical mechanism (strain rate-dependent) generated by the dense connective tissue as a function of strain. Results: As the ankle plantarflexion angle increased during landing, both the peak knee vertical impact force (p = 0.001) and ACL force (p = 0.001) decreased significantly. The maximum von Mises stress of ACL, meniscus, and femoral cartilage decreased as the ankle plantarflexion angle increased. The overall range of variation in ACL stress was small and was mainly distributed in the femoral and tibial attachment regions, as well as in the mid-lateral region. Conclusion: The current findings revealed that the use of larger ankle plantarflexion angles during landing may be an effective solution to reduce knee impact load and the risk of rupture of the medial femoral attachment area in the ACL. The findings of this study have the potential to offer novel perspectives in the optimized application of landing strategies, thus giving crucial theoretical backing for decreasing the risk of knee-related injury.

Open Access: Yes

DOI: 10.1016/j.compbiomed.2024.108965

Improvement the energy storage with ultracapacitor in metro railcar by modeling and simulation

István Szénásy

Publication Name: 2008 IEEE Vehicle Power and Propulsion Conference Vppc 2008

Publication Date: 2008-12-29

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

This paper focuses on the use of modeling and simulation for the renewable energy. An energy storage system for improving performance of electric vehicles is presented. The supercapacitor contributes to the rapid energy recovery associated with regenerative braking in electric vehicles. This power system allows the acceleration and deceleration of the vehicle with minimal loss of energy. Short-distance passenger traffic on electrified lines is a domain where brake energy recuperation might reduce the total energy consumption significantly. In this paper the results of simulation model by Matlab-Simulink for an urbanmetro railcar and the method for reduce the need value of capacitance are presented. © 2008 IEEE.

Open Access: Yes

DOI: 10.1109/VPPC.2008.4677664

Nodal and edge finite element analysis of eddy current field problems

Miklós Kuczmann

Publication Name: Przeglad Elektrotechniczny

Publication Date: 2008-12-01

Volume: 84

Issue: 12

Page Range: 194-197

Description:

Eddy current field problems can be solved by different potential formulations based on the "quasi-static" Maxwell's equations. The potential formulations are obtained using a vector potential and a scalar potential, the most widely used techniques are the A, V-A, the T,φ-φformulations and their combinations. Vector potentials can be approximated by nodal or edge finite elements, scalar potentials are approximated by scalar elements. The paper presents and compares these formulations through TEAM Problem No. 7 containing a multiply connected region.

Open Access: Yes

DOI: DOI not available

Overview of auditory representations in human-machine interfaces

Adam B. Csapo György Wersényi

Publication Name: ACM Computing Surveys

Publication Date: 2013-11-01

Volume: 46

Issue: 2

Page Range: Unknown

Description:

In recent years, a large number of research projects have focused on the use of auditory representations in a broadened scope of application scenarios. Results in such projects have shown that auditory elements can effectively complement other modalities not only in the traditional desktop computer environment but also in virtual and augmented reality, mobile platforms, and other kinds of novel computing environments. The successful use of auditory representations in this growing number of application scenarios has in turn prompted researchers to rediscover the more basic auditory representations and extend them in various directions. The goal of this article is to survey both classical auditory representations (e.g., auditory icons and earcons) and those auditory representations that have been created as extensions to earlier approaches, including speech-based sounds (e.g., spearcons and spindex representations), emotionally grounded sounds (e.g., auditory emoticons and spemoticons), and various other sound types used to provide sonifications in practical scenarios. The article concludes by outlining the latest trends in auditory interface design and providing examples of these trends.

Open Access: Yes

DOI: 10.1145/2543581.2543586

Beyond land use: Understanding variations in topsoil bulk versus recalcitrant organic matter

Tibor Filep Gabriella Darabos Csaba Centeri Zsuzsanna Angyal Balázs Madarász András Bidló Viktoria Vona Ákos Bede-Fazekas Gábor Szatmári Dóra Zacháry Csilla Király Máté Karlik Anna Vancsik Thulfiqar Al-Graiti Malihe Masoudi Zoltán Dévény Zoltán Szalai Gergely Jakab

Publication Name: Catena

Publication Date: 2024-09-01

Volume: 244

Issue: Unknown

Page Range: Unknown

Description:

Soil organic matter (SOM) concentration and composition are essential properties that affect most functions and ecosystem services. The relationship between soil and environmental covariates regarding SOM concentration and composition in various pools is not completely understood. This study aimed to identify the most influential drivers of SOM stabilization, focusing on arable lands in Hungary. Hungary is an ideal area for investigating SOM variability because it is at the meeting point of the three main climate effects that trigger a wide range of soil, land use, and topographical conditions. Overall, 87 soil samples were taken from the topsoil (2–20 cm) and fractionated (<20 µm) to separate the mineral phase-associated organic carbon (MAOC) and bulk pools. MAOC concentration varied on a wide range (0.5–14.1 %) and was the function of bulk SOM aromaticity and slope steepness, rather than land use, climatic conditions, or soil properties, indicating that MAOC is also affected by decomposition if the bulk OM is less available for the microbiome. Land use, especially in forest topsoils, reflects the elemental composition of the OM, focusing on the variations of residue composition. In contrast, aromaticity is rather related to soil and climate properties, suggesting increased relevance of transformation processes. As a consequence, SOM composition varies on a wide range in the topsoil, however, the lack of a definite trend at the county level suggests the complexity of the system and highlights the role of local circumstances.

Open Access: Yes

DOI: 10.1016/j.catena.2024.108232