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Found 6525 publications

An efficient new memetic method for the traveling salesman problem with time windows

Péter Földesi B. Tüű-Szabó Laszlo T. Koczy

Publication Name: Lecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics

Publication Date: 2017-01-01

Volume: 10607 LNAI

Issue: Unknown

Page Range: 426-436

Description:

In this paper we present a new memetic algorithm, which is called Discrete Bacterial Memetic Evolutionary Algorithm for solving the Traveling Salesman Problem with time windows (TSPTW). This method is the combination of bacterial evolutionary algorithm with 2-opt and 3-opt local searches. The algorithm was already tested on symmetric Traveling Salesman Problem (TSP) benchmark instances up to 5000 cities. It showed good properties in terms of tour lengths, runtimes and predictability of runtimes, so we decide to examine other variants of TSP with our algorithm. With some slight modifications our method was tested on TSP with time windows benchmark instances. Our test results were compared with the state-of-the art methods. In most cases our algorithm found the best-known solutions, and in terms of solution quality and runtime it is the second best method.

Open Access: Yes

DOI: 10.1007/978-3-319-69456-6_35

Structural behavior of built-up I-shaped CFS beams

Ardalan B. Hussein Diyari B. Hussein

Publication Name: Results in Engineering

Publication Date: 2024-12-01

Volume: 24

Issue: Unknown

Page Range: Unknown

Description:

The use of back-to-back built-up C-section beams is becoming increasingly common in CFS construction due to their cost-effectiveness and enhanced load-carrying capacity, making them suitable for longer beam spans and convenient for transportation. These built-up sections are utilized in wall studs, truss components, and floor joists, with intermediate screw fasteners placed at specific intervals to prevent the separate bowing of channels. This study reveals a ratio of 1.003 between experimental findings and finite element analysis results, and 1.002 between experimental findings and direct strength method results, indicating a strong correlation between experimental data from nonlinear finite element analysis and predictions based on the American Iron and Steel Institute and Australian and New Zealand Standards, particularly in predicting the flexural buckling strength of beam specimens. Furthermore, ongoing research is investigating the impact of screw spacing on flexural strength. This study presents results from 175 finite element tests, evaluating seven distinct cross-sections with twelve unique screw spacings. These spacings correspond to the half wavelength of local, distortional, and global buckling, divided by values from one to four. It was found that screw spacing based on half the local buckling half-wavelength along the centerline of the webs increased the critical global buckling moment capacity and the nominal flexural strength by 56 % and 27 %, respectively. For double-lane screws with the same spacing, these increases were even more substantial, reaching 65 % and 31 %, respectively. Economically, the recommended spacing for single-lane screws is half the local buckling half-wavelength.

Open Access: Yes

DOI: 10.1016/j.rineng.2024.102963

Calibration of Two Novel Segmentation Approaches by Synthetic Road Vehicle Vibrations

Péter Földesi László Róbert Hári

Publication Name: Tehnicki Vjesnik

Publication Date: 2024-01-01

Volume: 31

Issue: 6

Page Range: 2094-2101

Description:

Simulation of non-stationary random vibrations has motivated Packaging vibration testing for decades. Often, an event-detection algorithm decomposes Road vehicle vibrations when analyzing the recorded series. However, heuristics and subjective justifications are often in the papers, whereby the foremost concern is the validation of the non-stationarity of simulated signals. Furthermore, if a changepoint detection is inherent to the procedure, it is recommended to calibrate the detector. The current paper concerns the Receiver operating characteristics (ROC) of two novel algorithms and provides contextual support by Segment length distributions (SLD).

Open Access: Yes

DOI: 10.17559/TV-20220114115149

Design of acoustic cavity test apparatus for validation of mid-frequency response of a plate-cavity system

Dániel Feszty Tamas Turcsik Janos Kun

Publication Name: Proceedings of 2020 International Congress on Noise Control Engineering Inter Noise 2020

Publication Date: 2020-08-23

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The mid-frequency range acoustic response between 400-1000 Hz has gained particular interest in the automotive industry recently. Simulation of this region is challenging due to the non-negligible statistical effects, especially when acoustic trim is applied. In order to be able to investigate the effect of these materials in the presence of an air cavity, this paper describes the design methodology behind the design and manufacturing of two test apparatuses that include an air cavity. The apparatuses were designed to serve as a validation tool for Finite Element Method (FEM) and Statistical Energy Analysis (SEA) simulations, which meant that an optimal size had to be found based on the number of fluid modes in the cavity. Two types of plate-cavity apparatuses have been designed: one with “rigid walls” and one with “soft walls”. In the “rigid wall” cavity, the walls are made out of concrete since these boundary conditions can be perfectly represented in simulations. In the “soft wall” cavity, the walls are made of steel plates and this allows validation of coupling loss simulations between multiple structural subsystems as well as an air cavity. Details of the joining methods, geometries, material selections are elaborated to fully describe the theoretical and practical implications of the designs.

Open Access: Yes

DOI: DOI not available

Massive Open Online Courses (MOOCs) for Ethiopian Educators: Evaluating MOOCs as a global development tool

Seyoum Teffera Mengesha Sándor Remsei Belaynew Asrie Mola Éva Berde

Publication Name: Research in Globalization

Publication Date: 2024-12-01

Volume: 9

Issue: Unknown

Page Range: Unknown

Description:

This study examines how global educational technologies interact with local development priorities through the lens of Massive Open Online Courses (MOOCs) in Ethiopian higher education teacher training. While digital learning platforms promise to democratize education globally, their effectiveness depends critically on alignment with local institutional contexts and development needs. Using survey data from 164 educators across 15 public universities, we investigate how institutional contexts shape technology integration patterns. Our analysis, integrating development theory with technology acceptance models, reveals three critical dimensions: the gap between awareness and participation reflects broader implementation challenges; previous experiences with development initiatives significantly influence adoption patterns; and state support proves crucial for enabling participation. While MOOCs offer potential for professional development in resource-constrained contexts, their effectiveness depends on complex interactions among infrastructure quality, institutional capacity, and material conditions. These findings contribute to the theoretical understanding of how global technological innovations interact with local institutional contexts to produce varied development outcomes, while offering practical insights for educational technology implementation in the Global South.

Open Access: Yes

DOI: 10.1016/j.resglo.2024.100263

Organization learning and business resilience in developing hospitality industry

Mohammad Fakhrul Islam Anthony Chukwuma Nwali Friday Ogbu Edeh Johnson Nwokeiwu Chukwu Agnes Ugboego

Publication Name: Discover Sustainability

Publication Date: 2024-12-01

Volume: 5

Issue: 1

Page Range: Unknown

Description:

The study aims to investigate the effect of organizational learning on business resilience in developing the hospitality industry, specifically focusing on four-star hotels in the southeast region of Nigeria. One of the major reasons why this research was conducted is because of the vacuum that exists between organizational learning and business resilience in the hospitality industry. A cross-sectional survey design was employed because it supports using questionnaires to collect data from participants. A validated and reliable instrument was used to collect data from two hundred thirty one participants drawn from the selected hospitality industry in the southern part of Nigeria. The results demonstrate that organizational learning significantly positively affects business resilience. Organizational learning also affects crisis anticipation and recoverability which are crucial to be resilient in the industry. The results of this research supported prior empirical findings and supported both social learning theory and resilience theory. Regarding originality, the geographical scope and the industry where this research was conducted distinguish it from other prior empirical investigations. It was recommended that since the hospitality business is highly competitive, managers should utilize organizational learning as a strategy to overcome their competitors and remain sustainable in the industry. The findings of the research will contribute to the literature and hospitality industry in developing country contexts.

Open Access: Yes

DOI: 10.1007/s43621-024-00569-9

Scheduling Manufacturing with Flexible Recipes to Maximize the Utilization of Renewable Energy

Botond Bertok Károly Kalauz Márton Frits

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 955-960

Description:

The production schedule has a direct impact on the periodic utilization and energy consumption of equipment units. Meanwhile, for companies operating small power plants, the available renewable solar or wind energy changes continuously during the day, as does the hourly market price of the energy that can be purchased. Fortunately, the flexibility of production, possible schedules, or alternative recipes allow not only the minimization of costs but also the maximum use of renewable resources. The novelty of the P-graph-based method proposed here is the integration of three component problems into a single optimization model, namely the production scheduling by discrete event formulation, the management of flexible recipes by process synthesis, and the maximal renewable energy utilization according to discrete-time energy production and market price forecasts by representing them with temporarily available resources. The challenge of formalizing the optimization problem lies in synchronizing the time model of production scheduling with the resolution of market price and renewable energy production forecasts. The results show that the flexibility to alter both the sequence and schedule of operations by the integrated optimization model plays a critical role in optimizing energy usage.

Open Access: Yes

DOI: 10.3303/CET24114160

Aspects concerning the observation process modelling in the framework of cognition processes

Claudiu Pozna Radu Emil Precup

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2012-04-17

Volume: 9

Issue: 1

Page Range: 203-223

Description:

This paper presents results concerning the observation process modelling in the framework of cognition processes which belong to a new pattern of human knowledge. The cultural origin of the patterns is analyzed in terms of philosophical, psychological and linguistic points of view. A scenario concerning a robot integrated in a cognitive system is given in order to test the theoretical approaches. The definitions of signatures and of signature classes are given as one of the first steps in an alternative modelling approach to the observation process. An example that deals with the observation process modelling is offered.

Open Access: Yes

DOI: DOI not available

Impact of proximity from chemical and pharmaceutical universities on startup founding: empirical evidence from the Visegrad countries

Áron Szennay Petra Kinga Kézai Melinda Krankovits

Publication Name: Discover Sustainability

Publication Date: 2024-12-01

Volume: 5

Issue: 1

Page Range: Unknown

Description:

This paper examines the spatial distribution of chemical startups in the Visegrad Countries (Czech Republic, Slovakia, Poland, and Hungary), highlighting their potential to drive technological innovation by creating new products or services under conditions of high uncertainty. The study focuses on the proximity of these startups to medical or chemical universities and those with biotechnological research fields to better understand their geographical patterns and potential knowledge spillovers. Data were drawn from Crunchbase, a comprehensive startup database, resulting in a final sample of approximately 333 operational chemical, pharmaceutical, or biotechnological startups. Companies were identified using keyword-based searches, while startup locations and distances to the nearest medical universities were recorded. Statistical methods were applied to assess spatial patterns. Results indicate that these startups are frequently located in cities with biotechnological, chemical, or medical universities. Our findings highlight different types of startup activities and levels of financial support across the Visegrad countries, emphasising the role of chemical startups in fostering technological advancement and sustainable development.

Open Access: Yes

DOI: 10.1007/s43621-024-00707-3