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Found 6289 publications

Lattice boltzmann simulation of two-dimensional wall bounded turbulent flow

Gábor Tóth Gábor Házi

Publication Name: International Journal of Modern Physics C

Publication Date: 2010-05-01

Volume: 21

Issue: 5

Page Range: 669-680

Description:

This paper reports on a numerical study of two-dimensional decaying turbulence in a square domain with no-slip walls. The generation of strong small-scale vortices near the no-slip walls have been observed in the lattice Boltzmann simulations just like in earlier pseudospectral calculations. Due to these vortices the enstrophy is not a monotone decaying function of time. Considering a number of simulations and taking their ensemble average, we have found that the decay of enstrophy and that of the kinetic energy can be described well by power-laws. The exponents of these laws depend on the Reynolds number in a similar manner than was observed before in pseudospectral simulations. Considering the ensemble averaged 1D Fourier energy spectra calculated along the walls, we could not find a simple power-law, which fits well to the simulation data. These spectra change in time and reveal an exponent close to -3 in the intermediate and an exponent -5/3 at low wavenumbers. On the other hand, the two-dimensional energy spectra, which remain almost steady in the intermediate decay stage, show clear power-law behavior with exponent larger than -3 depending on the initial Reynolds number. © 2010 World Scientific Publishing Company.

Open Access: Yes

DOI: 10.1142/S0129183110015403

Destination marketing organization website features: cross-continental comparative analysis

Carla Fraga Lucília Cardoso Brahim Benbba Youssef El Archi

Publication Name: Journal of Qualitative Research in Tourism

Publication Date: 2025-10-01

Volume: 6

Issue: 1-2

Page Range: 116-126

Description:

Destination marketing organization (DMO) websites play a crucial role in influencing destination choice as more tourists in the digital age rely on the internet for travel-related information. This research note compares the functionality of DMO websites across three continents: Africa, Latin America, and Europe focusing on three countries (Morocco, Brazil, and Portugal). Based on an extensive framework developed by Li and Wang, this study carefully classifies and assesses website features using six dimensions (information, communication, transaction, relationship, technical merit, and brand gestalt cognition). The results offer destination marketing managers significant insights that aid in gap analysis and the improvement of website functionalities. In addition, the results of the research are applicable for evaluating website effectiveness and for deriving conclusions concern-ing management and business strategies. This research is also important for destinations as it provides practical opportunities for improving DMO websites, enhancing user engage-ment, and shaping destination choices in modern times.

Open Access: Yes

DOI: 10.4337/jqrt.2025.0020

Evaluation of a CUSUM-Type Changepoint Detector Applied in the Time-Frequency Domain of Synthetic Road Vehicle Vibrations

Peter Foldesi László Róbert Hári

Publication Name: Lecture Notes in Mechanical Engineering

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 812-823

Description:

Non-stationary random vibrations gained increasing interest in vibration testing. Often, a changepoint detection procedure handles the decomposition of Road vehicle vibrations (RVV) when analysing the recorded series. Unfortunately, only subjective justifications support the proposed methods, and mainly the validation of the non-stationarity of simulated signals is concerned. Thus, if a detector is inherent to the procedure, it is also recommended to calibrate it. The current paper concerns the Receiver operating characteristics (ROC) of a CUSUM-type algorithm and supplies contextual support by Segment length distributions (SLD).

Open Access: Yes

DOI: 10.1007/978-3-031-15211-5_67

Genome-Wide Association Study of Exercise Addiction Among Elite Wrestlers

Ildus I. Ahmetov Seyrani Koncagul Mehmet A. Ergun Hasan H. Kazan Celal Bulgay Anıl Kasakolu Mark D. Griffiths Türker Bıyıklı Mark D. Griffiths Attila Szabo

Publication Name: Brain Sciences

Publication Date: 2025-02-01

Volume: 15

Issue: 2

Page Range: Unknown

Description:

Background: Exercise addiction, marked by an inability to control exercise and associated with distress that clinically impairs daily activities, is a significant but underrecognized issue in physical activity and health. While its physiological, psychological, and behavioral aspects have been studied, the genetic basis of exercise addiction remains poorly understood, requiring further investigation. The present study conducted a genome-wide association study of exercise addiction among elite Turkish wrestlers. Methods: The sample comprised 67 male wrestlers (34 freestyle wrestlers and 33 Greco-Roman wrestlers). Exercise addiction was assessed using the Exercise Addiction Scale. Whole-genome genotyping was performed using DNA microarray. Results: Using a genome-wide approach (p < 1.0 × 10−⁵), we identified six suggestively significant single-nucleotide polymorphisms (SNPs) associated with exercise addiction status. Of these, the high-addiction alleles of five SNPs (PRDM10 rs74345126, near PTPRU rs72652685, HADHB rs6745226, XIRP2 rs17614860, and near GAREM2 rs1025542) have previously been associated with an increased risk of mental health disorders such as anxiety and depression or higher levels of physical activity. We also examined potential associations between the genetic markers previously linked to addiction-related traits such as obsessive–compulsive disorder and cigarette smoking, and personality traits linked to negative emotions including neuroticism. Using this candidate gene approach (p < 0.05), we identified three additional SNPs associated with exercise addiction in the same direction of association (DEFB135 rs4841662, BCL11A rs7599488, and CSRNP3 rs1551336). Conclusions: The present study provides preliminary evidence for the genetic basis of exercise addiction, highlighting specific SNPs that may play a role in the development of this condition among elite wrestlers.

Open Access: Yes

DOI: 10.3390/brainsci15020102

The role of knowledge management in developing quality culture

Horváth Csikós Gabriella Bencsik Andrea

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2018-01-01

Volume: 15

Issue: 8

Page Range: 209-226

Description:

The study reveals the connecting points, where the elements of knowledge management system as part of the corporate processes (studiously the quality systems) play an important role in the successful operation of the company. The characteristic features of quality culture are in focus, of which support is put in parallel with the characteristic features of the learning organisation’s culture phrased as a precondition of knowledge management system. With this comparison, the author guarantees the understanding that by solving quality problems and developing quality culture with supporting the elements of knowledge management system will contribute to reaching corporate success and strategic goals.

Open Access: Yes

DOI: 10.12700/APH.15.8.2018.8.11

Image-Based Estimation of Porosity and Tortuosity in Fibrous Acoustic Absorbers

Krisztian Horvath Attila Schweighardt Krisztián Horváth Krisztián Horváth

Publication Name: Engineering Reports

Publication Date: 2025-12-01

Volume: 7

Issue: 12

Page Range: Unknown

Description:

This study presents a fast and non-destructive image-based method for estimating two key acoustic parameters—open porosity and tortuosity—in fibrous sound-absorbing materials. The approach uses a single grayscale optical micrograph, which is down-sampled, contrast-equalized, and segmented via adaptive thresholding. From the resulting binary fiber mask, two geometric descriptors are extracted: coverage and a one-pixel-wide skeleton. Porosity is estimated using a simple linear formula calibrated on three reference materials, yielding an average absolute error below 0.3% when compared with argon gas pycnometry. Tortuosity is inferred from the total skeleton length relative to the image area, producing a stable ranking across materials with consistent bias relative to measured data. Additionally, a random forest model using only three image features—coverage, median fiber radius, and skeleton length—predicts airflow resistivity with over 70% explained variance. The full analysis pipeline is implemented in Python using open-source libraries (OpenCV, scikit-image) and runs in under half a second per image on standard hardware. This makes the method well suited for early-stage material screening, in-line quality control, or laboratory support, without the need for destructive testing or costly instruments. The approach bridges the gap between optical imaging and physical parameter estimation, offering a lightweight alternative to traditional porosity and impedance-tube measurements.

Open Access: Yes

DOI: 10.1002/eng2.70537

Optimal plastic analysis and design of pile foundations under reliable conditions

Majid Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-07-13

Volume: 65

Issue: 3

Page Range: 761-767

Description:

In this research, in order to evaluate the plastic limit load and also plastic design parameters of the long pile foundations subjected to horizontal loads, shakedown method is applied. In carrying out shakedown analysis and design methods, large plastic deformations and residual displacements could develop in the pile foundation which might lead to the failure of the structure. For this reason, complementary strain energy of residual forces proposed as a limit condition to control the plastic deformation of the pile structure. Furthermore, considering the uncertainties (strength, manufacturing, geometry) the limit conditions on the complementary strain energy of residual forces are assumed randomly and the reliability condition was formed by the use of the strict reliability index. The influence of the limit conditions on the plastic limit load and design parameters of the long pile in cohesionless soil subjected to lateral load were investigated and limit curves for shakedown load factors are presented. The numerical results show that the probabilistic given limit conditions on the complementary strain energy of residual forces have significant influence on the load bearing limit and the design parameters of pile foundations. The formulations of the reliability based problems lead to mathematical programming which were carried out by the use of non-linear algorithm.

Open Access: Yes

DOI: 10.3311/PPci.17402

A Preliminary Study on Laser Surface Texturing of Passenger Car Engine Piston Rings

András Lajos Nagy Attila Schweighardt Gabor Laki Gergely Kovács

Publication Name: Fme Transactions

Publication Date: 2025-01-01

Volume: 53

Issue: 2

Page Range: 252-259

Description:

Laser surface texturing offers a possible solution for reducing friction between sliding surfaces in engineering applications. Optimized surface topography can also contribute to reduced wear and elevated longevity by modifying the load and speed-dependent friction state in a system. This preliminaryexperimental study investigates the applicability of affordable fibre laser marking systems for microtexturing piston rings, in order to achieve a measurable reduction in friction under subsystem model conditions. A selection of textures are applied to chromium-coated cast iron piston rings. The resulting surface topographies are characterized through confocal microscopy and subjected to friction testing. A correlation analysis is conducted on surface topography parameters to identify key laser process parameters. Findings indicate an improvement in the range of 7–8% in terms of friction coefficient with appropriate texture size.

Open Access: Yes

DOI: 10.5937/fme2502252L

Bacterial memetic algorithm for offline path planning of mobile robots

János Botzheim Yuichiro Toda Naoyuki Kubota

Publication Name: Memetic Computing

Publication Date: 2012-03-01

Volume: 4

Issue: 1

Page Range: 73-86

Description:

The goal of the path planning problem is to determine an optimal collision-free path between a start and a target point for a mobile robot in an environment surrounded by obstacles. This problem belongs to the group of combinatorial optimization problems which are approached by modern optimization techniques such as evolutionary algorithms. In this paper the bacterial memetic algorithm is proposed for path planning of a mobile robot. The objective is to minimize the path length and the number of turns without colliding with an obstacle. The representation used in the paper fits well to the algorithm. Memetic algorithms combine evolutionary algorithms with local search heuristics in order to speed up the evolutionary process. The bacterial memetic algorithm applies the bacterial operators instead of the genetic algorithm's crossover and mutation operator. One advantage of these operators is that they easily can handle individuals with different length. The method is able to generate a collision-free path for the robot even in complicated search spaces. The proposed algorithm is tested in real environment. © 2012 Springer-Verlag.

Open Access: Yes

DOI: 10.1007/s12293-012-0076-0