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Found 6374 publications
Effect of the Particle Size Distribution of the Ballast on the Lateral Resistance of Continuously Welded Rail Tracks
Publication Name: Infrastructures
Publication Date: 2024-08-01
Volume: 9
Issue: 8
Page Range: Unknown
Description:
While the effect of ballast degradation on lateral resistance is noteworthy, limited research has delved into the specific aspect of ballast breakage in this context. This study is dedicated to assessing the influence of breakage on sleeper lateral resistance. For simplicity, it is assumed that ballast breakage has already occurred. Accordingly, nine granularity variations finer than No. 24 were chosen for simulation, with No. 24 as the assumed initial particle size distribution. Initially, a DEM model was validated for this purpose using experimental outcomes. Subsequently, employing this model, the lateral resistance of different particle size distributions was examined for a 3.5 mm displacement. The track was replaced by a reinforced concrete sleeper in the models, and no rails or rail fasteners were considered. The sleeper had a simplified model with clumps, the type of which was the so-called B70 and was applied in Western Europe. The sleeper was taken into consideration as a rigid body. The crushed stone ballast was considered as spherical grains with the addition that they were divided into fractions (sieves) in weight proportions (based on the particle distribution curve) and randomly generated in the 3D model. The complete 3D model was a 4.84 × 0.6 × 0.57 m trapezoidal prism with the sleeper at the longitudinal axis centered and at the top of the model. Compaction was performed with gravity and slope walls, with the latter being deleted before running the simulation. During the simulation, the sleeper was moved horizontally parallel to its longitudinal axis and laterally up to 3.5 mm in static load in the compacted ballast. The study successfully established a relationship between lateral resistance and ballast breakage. The current study’s findings indicate that lateral resistance decreases as ballast breakage increases. Moreover, it was observed that the rate of lateral resistance decrease becomes zero when the ballast breakage index reaches 0.6.
Open Access: Yes
Extended Solution of a Trimmed Vehicle Finite Element Model in the Mid-Frequency Range
Publication Name: SAE Technical Papers
Publication Date: 2020-09-30
Volume: Unknown
Issue: 2020
Page Range: Unknown
Description:
The acoustic trim components play an essential role in Noise, Vibration and Harshness (NVH) behavior by reducing both the structure borne and airborne noise transmission while participating to the absorption inside the car and the damping of the structure. Over the past years, the interest for numerical solutions to predict the noise including trim effects in mid-frequency range has grown, leading to the development of dedicated CAE tools. Finite Element (FE) models are an established method to analyze NVH problems. FE analysis is a robust and versatile approach that can be used for a large number of applications, like noise prediction inside and outside the vehicle due to different sources or pass-by noise simulation. Typically, results feature high quality correlations. However, future challenges, such as electric motorized vehicles, with changes of the motor noise spectrum, will require an extension of the existing approaches. In this paper, the vibro-acoustic frequency response of an existing MSC Nastran FE model is extended using the Actran Statistical Energy Analysis (SEA) approach, Virtual SEA. In Virtual SEA, the necessary information required to build the SEA system is extracted from the FE models. The fluid-structure Coupling Loss Factors (CLF) are computed through the Statistical modal Energy distribution Analysis (SmEdA) method. This method is a suitable candidate to account for acoustic trim effects based on analytical approach. The case studied consists of a trimmed body car model transfer function calculation. The result of the case study is an extensive correlation study containing measured and simulated transfer functions in low and mid-frequency range. Simulation results are derived from two approaches, FE method and Virtual SEA method.
Open Access: Yes
DOI: 10.4271/2020-01-1549
EXAMINING THE DEMAND RELATIONSHIPS OF BETWEEN RELIGIOUS TOURISM AND EXAMPLE OF URBAN ATTRACTIONS IN THE GYŐR-PANNONHALMA TOURIST AREA
Publication Name: Geojournal of Tourism and Geosites
Publication Date: 2024-01-01
Volume: 57
Issue: Unknown
Page Range: 2114-2122
Description:
This study examines the sacred places of Győr-Moson-Sopron County (Western Hungary), focusing on people's attitudes towards them. Pannonhalma is part of the world heritage, the Győr Cathedral, and the five church festivals (Roman Catholic, Jewish, Reformed, Lutheran, Greek Oriental) held in the city are important places of worship. The aim of the study was to analyse the scope of religious tourism in the World Heritage Site and to examine the demographics of the demand for urban religious centres. Primary research was conducted with a quantitative (questionnaire) survey between 10th September 2023 and 30th October 2023. The sample of 666 persons is not representative, respondents were chosen with arbitrary sampling. Data were processed using the SPSS 23 statistical program package which contains cross-table analysis, in addition to the descriptive statistical analyses. The most important finding of the study is that travel propensity is determined by the importance and familiarity of urban landmarks, and significance can be found here. Respondents' age, educational attainment and gender also show significant differences in terms of the attractiveness of visiting attractions (distance from their residence). The research investigated the demand for Roman Catholic, Jewish, Reformed, Evangelical and Greek Orthodox religious attractions in Győr and the Pannonhalma Benedictine Abbey, a World Heritage Site, according to local specificity. There is significant evidence of a regional pull effect of the World Heritage status of the built heritage site. The city churches and their associated events are most popular with the elderly, women and those with higher education.
Open Access: Yes
Urban Vulnerability and Earthquake Risks Incorporating Sustainability
Publication Name: Chemical Engineering Transactions
Publication Date: 2023-01-01
Volume: 107
Issue: Unknown
Page Range: 607-612
Description:
Amidst the backdrop of rapid global urbanization, this research delves deep into the nexus of urban vulnerabilities, seismic challenges, and sustainable infrastructure. As cities sprawl, the need to adapt and refine traditional building techniques becomes evident, especially in the quest for seismic resilience and ecological sustainability. The study introduces the innovative 'Sustainable Seismic Design' framework. A core component of the research is the quantitative material evaluation. Materials, notably Engineered Timber and Concrete, are assessed on their seismic resistance—measuring their capacity to withstand seismic forces and dissipate energy during earthquakes. Concurrently, their environmental impact is evaluated, considering factors like energy consumption during production, emissions, and recyclability. Engineered Timber emerges with a commendable 50 % higher environmental score, underscoring its eco-friendly nature compared to Concrete. Further, the research illuminates the often-overlooked geotechnical elements, such as soil characteristics and groundwater dynamics, that can amplify seismic vulnerabilities. The advocacy for green geotechnical strategies is accentuated, with the post-seismic rebuilding endeavors in Christchurch, New Zealand, serving as a practical exemplar of the benefits of this integrative strategy. In essence, the study champions policy adaptations that seamlessly weave sustainability into seismic construction standards and geotechnical practices, setting the stage for urban habitats that are both resilient to earthquakes and champions of green initiatives.
Open Access: Yes
DOI: 10.3303/CET23107102
Aerodynamic Behavior of Hump Slab Track in Desert Railways: A Case Study in Shuregaz, Iran
Publication Name: Buildings
Publication Date: 2024-08-01
Volume: 14
Issue: 8
Page Range: Unknown
Description:
The development of rail transport necessitates expanding environmentally friendly infrastructure. However, specific challenges arise in desert and sandy regions. One innovative solution to manage the effects of windblown sand on desert railways is the use of hump slab track superstructure. This paper develops a solid–fluid aerodynamic model based on ANSYS Fluent 2021 R2 software to simulate the hump slab track during a sandstorm. The model is validated through wind tunnel testing. A case study of a railway sandstorm in the Shuregaz region of Iran is presented, evaluating various sandstorm parameters and hump heights to determine their impact on sand concentration and particle velocity within the sand transit channels. The results indicate that increasing the sand particle diameter (from 150 to 250 µm) leads to higher sand concentration (up to 40%) and lower sand movement velocity (up to 28%). These results have been observed with a higher incremental approach concerning the sand flow rate. Conversely, increasing sandstorm velocity (from 10 to 30 m/s) decreases sand concentration and increases sand movement velocity up to 80% and 150%, respectively. Additionally, a 25 cm hump height significantly enhances sand passage by creating larger channels.
Open Access: Yes
Approximation of force and energy in vehicle crash using LPV type description
No authors available
Publication Name: WSEAS Transactions on Systems
Publication Date: 2010-07-01
Volume: 9
Issue: 7
Page Range: 734-743
Description:
In accident analysis, vehicle crash mechanics and vehicle safety research modeling of the deformational force and absorbed energy plays a crucial role. The usually applied FEM based methods give good approximations, but they have extremely large computational complexity and require a detailed knowledge about the parameteres of the crash and the vehicle. There are simpler models, but they not give satisfactory approximation. In this paper using the LPV-HOSVD paradigm we introduce a model for vehicle deformation process, which well approximates the deformation force and the absorbed energy, moreover it has acceptable computational complexity.
Open Access: No
DOI: DOI not available
Historical origin of the fine structure constant subtilis structurae constan unit s1 part i. St. Stephen's crowning achievement
No authors available
Publication Name: Acta Polytechnica Hungarica
Publication Date: 2010-05-31
Volume: 7
Issue: 1
Page Range: 119-157
Description:
This paper deals with the historical origin of the primordial image of the fine structure constant (FSC) and the number 137 as the Self's own number archetype, which plays a central role in the poetic-hermeneutic system of the Holy Crown of Hungary. We intend to show that the allegorical and symbolical images which are observed as the manifestation of unconscious and interpreted and analyzed in the Pauli-Jung collaboration have a lengthy synchronistic relationship with the "archetypal model" of the FSC found in the marvellous enamel pictures of St. Stephen's Crown.
Open Access: No
DOI: DOI not available
Collaborative precise modeling of fuel cells based on adaptive Huber loss function and wild horse optimizer with critical statistical analysis
Publication Name: International Journal of Hydrogen Energy
Publication Date: 2026-06-15
Volume: 242
Issue: Unknown
Page Range: Unknown
Description:
Precise estimation of fuel cell parameters is critical for optimizing performance and developing energy systems. However, experimental data are often affected by outliers stemming from inaccurate measurements, transient operating conditions, or environmental variations. In this line, this study proposes a robust approach for estimating proton exchange membrane fuel cell (PEMFC) parameters. This study focuses on the steady-state current–voltage (I–V) characteristics and performs parameter extraction for a semi-empirical model. The proposed estimation framework employs the collaboration of the Huber loss function (HLF) in conjunction with adaptive hyperparameter and the metaheuristic Wild Horse Optimizer (WHO) to compute seven unknown PEMFC parameters. The impact of different hyperparameter (δ) values is examined on the performance of the HLF while estimating key fuel cell parameters. The sensitivity of the estimating process to the δ-value is explored using measured and estimated datasets, including accuracy, convergence rate, and resilience. The WHO-based approach is adopted to address and mitigate issues such as premature convergence and entrapment in local optima, which are common challenges in existing optimization strategies. The proposed model has been tested and verified through three test samples of standard commercial PEMFC units as benchmarks. The simulation results demonstrate that the WHO exhibits robust performance across the three benchmark PEMFC systems. Furthermore, the proposed model's generalization capability is validated under a range of operating conditions using polarization curves generated at different temperatures and cathode stoichiometries. A single globally specified parameter set reliably predicts fuel cell performance across these diverse conditions, as evidenced by its consistent ability to deliver high-quality solutions with an extraordinary level of precision under predefined experimental conditions. The proposed estimation framework outperforms three commercial PEMFC units (NedStack-PS6, Horizon-500 W, and BCS-500W), achieving Huber loss values of 1.03277845, 0.00562094, and 0.00584889, respectively. The adaptive HLF with hyperparameter (δ) ranging from 0.5 to 2.0 efficiently tackles outliers and improves convergence speed. While the hyperparameter (δ) in previous studies was kept constant, δ = 1. The proposed estimation framework closely matches the experimental data and offers significantly higher accuracy compared to existing competing methods in the literature. The results reveal that the suggested HLF enhances the robustness and immunity of the WHO optimizer, and it outperforms traditional approaches such as steady-state error.
Open Access: Yes
Methodology for DNS cache poisoning vulnerability analysis of DNS64 implementations
Publication Name: Infocommunications Journal
Publication Date: 2018-06-01
Volume: 10
Issue: 2
Page Range: 13-25
Description:
The trustworthy operation of the DNS service is a very important precondition for a secure Internet. As we point it out, DNS cache poisoning could be even more dangerous if it is performed against DNS64 servers. Based on RFC 5452, we give an introduction to the three main components of DNS cache poisoning vulnerability, namely Transaction ID prediction, source port number prediction, and a birthday paradox based attack, which is possible if a DNS or DNS64 server sends out multiple equivalent queries (with identical QNAME, QTYPE, and QCLASS fields) concurrently. We design and implement a methodology and a testbed, which can be used for the systematic testing of DNS or DNS64 implementations, whether they are susceptible to these three vulnerabilities. We perform the tests with the following DNS64 implementations: BIND, PowerDNS, Unbound, TOTD (two versions) and mtd64-ng. As for the testbed, we use three virtual Linux machines executed by a Windows 7 host. As for tools, we use VMware Workstation 12 Player for virtualization, Wireshark and tshark for monitoring, dns64perf for Transaction ID and source port predictability tests, and our currently developed “birthday-test” program for concurrently sent multiple equivalent queries testing. Our methodology can be used for DNS cache poisoning vulnerability analysis of further DNS or DNS64 implementations. A testbed with the same structure may be used for security vulnerability analysis of DNS or DNS64 servers and also NAT64 gateways concerning further threats.
Open Access: Yes
DOI: DOI not available
