The operation of state-of-the-art battery electric buses (BEBs) has started recently, and their consumption model is unknown. Therefore, the service providers are lenient regarding the energy used. Our aim was to reveal the effects of ambient temperature and bus service characteristics, such as passenger load and delay, on the energy consumption. Real-time consumption data of BEBs were analyzed in Nyíregyháza, Hungary, and the functional relationships among the aforementioned variables were revealed. We found that while ambient temperature is negatively correlated with consumption in the cold winter periods, the consumption surplus is positively correlated with passenger load and generally positively correlated with the delay on the trip because of road traffic. In the case of delay, the consumption increase is caused by more frequent acceleration and the greater consumption of auxiliary systems due to longer running times. Accordingly, the energy consumption can be estimated if the characteristics data are available. The results can be used by bus service operators to plan the daily schedule and predict the energy consumption of a BEB.
{"title":"Impact of Ambient Temperature, Passenger Load, and Delay on the Consumption of Battery Electric Buses","authors":"P. Szilassy, Dávid Földes","doi":"10.3311/pptr.23478","DOIUrl":"https://doi.org/10.3311/pptr.23478","url":null,"abstract":"The operation of state-of-the-art battery electric buses (BEBs) has started recently, and their consumption model is unknown. Therefore, the service providers are lenient regarding the energy used. Our aim was to reveal the effects of ambient temperature and bus service characteristics, such as passenger load and delay, on the energy consumption. Real-time consumption data of BEBs were analyzed in Nyíregyháza, Hungary, and the functional relationships among the aforementioned variables were revealed. We found that while ambient temperature is negatively correlated with consumption in the cold winter periods, the consumption surplus is positively correlated with passenger load and generally positively correlated with the delay on the trip because of road traffic. In the case of delay, the consumption increase is caused by more frequent acceleration and the greater consumption of auxiliary systems due to longer running times. Accordingly, the energy consumption can be estimated if the characteristics data are available. The results can be used by bus service operators to plan the daily schedule and predict the energy consumption of a BEB.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"6 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139796101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The operation of state-of-the-art battery electric buses (BEBs) has started recently, and their consumption model is unknown. Therefore, the service providers are lenient regarding the energy used. Our aim was to reveal the effects of ambient temperature and bus service characteristics, such as passenger load and delay, on the energy consumption. Real-time consumption data of BEBs were analyzed in Nyíregyháza, Hungary, and the functional relationships among the aforementioned variables were revealed. We found that while ambient temperature is negatively correlated with consumption in the cold winter periods, the consumption surplus is positively correlated with passenger load and generally positively correlated with the delay on the trip because of road traffic. In the case of delay, the consumption increase is caused by more frequent acceleration and the greater consumption of auxiliary systems due to longer running times. Accordingly, the energy consumption can be estimated if the characteristics data are available. The results can be used by bus service operators to plan the daily schedule and predict the energy consumption of a BEB.
{"title":"Impact of Ambient Temperature, Passenger Load, and Delay on the Consumption of Battery Electric Buses","authors":"P. Szilassy, Dávid Földes","doi":"10.3311/pptr.23478","DOIUrl":"https://doi.org/10.3311/pptr.23478","url":null,"abstract":"The operation of state-of-the-art battery electric buses (BEBs) has started recently, and their consumption model is unknown. Therefore, the service providers are lenient regarding the energy used. Our aim was to reveal the effects of ambient temperature and bus service characteristics, such as passenger load and delay, on the energy consumption. Real-time consumption data of BEBs were analyzed in Nyíregyháza, Hungary, and the functional relationships among the aforementioned variables were revealed. We found that while ambient temperature is negatively correlated with consumption in the cold winter periods, the consumption surplus is positively correlated with passenger load and generally positively correlated with the delay on the trip because of road traffic. In the case of delay, the consumption increase is caused by more frequent acceleration and the greater consumption of auxiliary systems due to longer running times. Accordingly, the energy consumption can be estimated if the characteristics data are available. The results can be used by bus service operators to plan the daily schedule and predict the energy consumption of a BEB.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"27 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139855778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A recent trend of increase in the vulnerable behavior of roads to potential climate events is observed worldwide. However, a few studies conducted incorporate climate impact into road maintenance and rehabilitation. To address this, a genetic algorithm (GA) based optimization approach is proposed in this study with a climate risk index (CRI) in terms of criticality of roads, probability of occurrence of a climate event, and existing severity level of pavement. Criticality is defined by road functional class, availability of alternative routes and land use. Probability is determined by historical events and topography, while severity is defined by existing pavement condition. The CRI is incorporated as a generic constraint to the GA-based optimization model to maximize the average network condition under a given budget. To demonstrate this, a case study is conducted using twenty roads in different climatic conditions in Sri Lanka. The results show that in 25% and 50% of required total budget conditions there is a clear separation between priority roads IRI and non-priority roads IRI due to the generic constraint. This is an indication that the optimization model effectively prioritizes roads when there is a budget constraint. This concludes that the proposed approach can be utilized to make the most of the available budget for road maintenance by prioritizing roads that are highly vulnerable to climate events without compromising the overall network condition. Further, the proposed maintenance optimization approach can be extended to long term maintenance planning economically for developing countries.
最近，全球范围内的道路易受潜在气候事件影响的情况呈上升趋势。然而，很少有研究将气候影响纳入道路维护和修复中。为解决这一问题，本研究提出了一种基于遗传算法（GA）的优化方法，并根据道路的关键性、气候事件发生的概率以及路面现有的严重程度，制定了气候风险指数（CRI）。关键性由道路功能等级、替代路线的可用性和土地使用情况决定。概率由历史事件和地形决定，而严重程度则由现有路面状况决定。CRI 是基于 GA 的优化模型的通用约束条件，目的是在给定预算的情况下最大限度地提高网络的平均状况。为了证明这一点，我们利用斯里兰卡不同气候条件下的 20 条道路进行了案例研究。结果表明，在所需总预算的 25% 和 50% 的条件下，由于采用了通用约束条件，优先道路 IRI 和非优先道路 IRI 有了明显的区分。这表明，当存在预算限制时，优化模型能有效地确定道路的优先次序。由此得出结论，建议的方法可以在不影响整体网络状况的前提下，优先考虑那些极易受气候事件影响的道路，从而最大限度地利用道路维护的可用预算。此外，建议的维护优化方法还可扩展到发展中国家的长期经济维护规划。
{"title":"A Genetic Algorithm-based Decision Framework to Incorporate Climate Impact on Pavement Maintenance Planning","authors":"Sachini Madushani, Kelum Sandamal, Tharindu Rangajeewa","doi":"10.3311/pptr.22290","DOIUrl":"https://doi.org/10.3311/pptr.22290","url":null,"abstract":"A recent trend of increase in the vulnerable behavior of roads to potential climate events is observed worldwide. However, a few studies conducted incorporate climate impact into road maintenance and rehabilitation. To address this, a genetic algorithm (GA) based optimization approach is proposed in this study with a climate risk index (CRI) in terms of criticality of roads, probability of occurrence of a climate event, and existing severity level of pavement. Criticality is defined by road functional class, availability of alternative routes and land use. Probability is determined by historical events and topography, while severity is defined by existing pavement condition. The CRI is incorporated as a generic constraint to the GA-based optimization model to maximize the average network condition under a given budget. To demonstrate this, a case study is conducted using twenty roads in different climatic conditions in Sri Lanka. The results show that in 25% and 50% of required total budget conditions there is a clear separation between priority roads IRI and non-priority roads IRI due to the generic constraint. This is an indication that the optimization model effectively prioritizes roads when there is a budget constraint. This concludes that the proposed approach can be utilized to make the most of the available budget for road maintenance by prioritizing roads that are highly vulnerable to climate events without compromising the overall network condition. Further, the proposed maintenance optimization approach can be extended to long term maintenance planning economically for developing countries.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"77 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139810807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A recent trend of increase in the vulnerable behavior of roads to potential climate events is observed worldwide. However, a few studies conducted incorporate climate impact into road maintenance and rehabilitation. To address this, a genetic algorithm (GA) based optimization approach is proposed in this study with a climate risk index (CRI) in terms of criticality of roads, probability of occurrence of a climate event, and existing severity level of pavement. Criticality is defined by road functional class, availability of alternative routes and land use. Probability is determined by historical events and topography, while severity is defined by existing pavement condition. The CRI is incorporated as a generic constraint to the GA-based optimization model to maximize the average network condition under a given budget. To demonstrate this, a case study is conducted using twenty roads in different climatic conditions in Sri Lanka. The results show that in 25% and 50% of required total budget conditions there is a clear separation between priority roads IRI and non-priority roads IRI due to the generic constraint. This is an indication that the optimization model effectively prioritizes roads when there is a budget constraint. This concludes that the proposed approach can be utilized to make the most of the available budget for road maintenance by prioritizing roads that are highly vulnerable to climate events without compromising the overall network condition. Further, the proposed maintenance optimization approach can be extended to long term maintenance planning economically for developing countries.
最近，全球范围内的道路易受潜在气候事件影响的情况呈上升趋势。然而，很少有研究将气候影响纳入道路维护和修复中。为解决这一问题，本研究提出了一种基于遗传算法（GA）的优化方法，并根据道路的关键性、气候事件发生的概率以及路面现有的严重程度，制定了气候风险指数（CRI）。关键性由道路功能等级、替代路线的可用性和土地使用情况决定。概率由历史事件和地形决定，而严重程度则由现有路面状况决定。CRI 是基于 GA 的优化模型的通用约束条件，目的是在给定预算的情况下最大限度地提高网络的平均状况。为了证明这一点，我们利用斯里兰卡不同气候条件下的 20 条道路进行了案例研究。结果表明，在所需总预算的 25% 和 50% 的条件下，由于采用了通用约束条件，优先道路 IRI 和非优先道路 IRI 有了明显的区分。这表明，当存在预算限制时，优化模型能有效地确定道路的优先次序。由此得出结论，建议的方法可以在不影响整体网络状况的前提下，优先考虑那些极易受气候事件影响的道路，从而最大限度地利用道路维护的可用预算。此外，建议的维护优化方法还可扩展到发展中国家的长期经济维护规划。
{"title":"A Genetic Algorithm-based Decision Framework to Incorporate Climate Impact on Pavement Maintenance Planning","authors":"Sachini Madushani, Kelum Sandamal, Tharindu Rangajeewa","doi":"10.3311/pptr.22290","DOIUrl":"https://doi.org/10.3311/pptr.22290","url":null,"abstract":"A recent trend of increase in the vulnerable behavior of roads to potential climate events is observed worldwide. However, a few studies conducted incorporate climate impact into road maintenance and rehabilitation. To address this, a genetic algorithm (GA) based optimization approach is proposed in this study with a climate risk index (CRI) in terms of criticality of roads, probability of occurrence of a climate event, and existing severity level of pavement. Criticality is defined by road functional class, availability of alternative routes and land use. Probability is determined by historical events and topography, while severity is defined by existing pavement condition. The CRI is incorporated as a generic constraint to the GA-based optimization model to maximize the average network condition under a given budget. To demonstrate this, a case study is conducted using twenty roads in different climatic conditions in Sri Lanka. The results show that in 25% and 50% of required total budget conditions there is a clear separation between priority roads IRI and non-priority roads IRI due to the generic constraint. This is an indication that the optimization model effectively prioritizes roads when there is a budget constraint. This concludes that the proposed approach can be utilized to make the most of the available budget for road maintenance by prioritizing roads that are highly vulnerable to climate events without compromising the overall network condition. Further, the proposed maintenance optimization approach can be extended to long term maintenance planning economically for developing countries.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"73 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139870687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to investigate the performance of artificially aged prototype engine oils through friction and wear experiments. Experiments were performed on a piston ring – cylinder liner model system with boundary conditions derived from real-life operating conditions. The experimental design implemented two prototype oils (SAE 0W-12 and 0W-16) in unaltered and artificially aged form. An additional fully formulated off-the-shelf engine oil (SAE 0W-20) was also aged and analyzed as reference. Oil samples were artificially aged in a custom rig, to simulate long-term in-engine use through thermal cycling at 180 °C. Fourier Transformed Infrared Spectroscopy of the lubricant samples highlighted a depletion of zinc dialkyl-ditiophosphate antiwear additives in all cases, which is comparable to a selected in-service oil. Oxidation was also measurable, albeit lower compared to the in-service sample. Averaged friction coefficients showed a ranking of aged 0W-12 < aged 0W-16 < unaltered 0W-12 < unaltered 0W-16. A decrease in surface roughness was experienced with aged oil samples, whereas unaltered 0W-16 oil produced an unexpected transition in the wear phenomenon and resulted in severe wear.
{"title":"Friction and Wear of the Piston Ring – Cylinder Liner System with Artificially Aged Ultra-low Viscosity Engine Oils","authors":"András Lajos Nagy","doi":"10.3311/pptr.22918","DOIUrl":"https://doi.org/10.3311/pptr.22918","url":null,"abstract":"This study aims to investigate the performance of artificially aged prototype engine oils through friction and wear experiments. Experiments were performed on a piston ring – cylinder liner model system with boundary conditions derived from real-life operating conditions. The experimental design implemented two prototype oils (SAE 0W-12 and 0W-16) in unaltered and artificially aged form. An additional fully formulated off-the-shelf engine oil (SAE 0W-20) was also aged and analyzed as reference. Oil samples were artificially aged in a custom rig, to simulate long-term in-engine use through thermal cycling at 180 °C. Fourier Transformed Infrared Spectroscopy of the lubricant samples highlighted a depletion of zinc dialkyl-ditiophosphate antiwear additives in all cases, which is comparable to a selected in-service oil. Oxidation was also measurable, albeit lower compared to the in-service sample. Averaged friction coefficients showed a ranking of aged 0W-12 < aged 0W-16 < unaltered 0W-12 < unaltered 0W-16. A decrease in surface roughness was experienced with aged oil samples, whereas unaltered 0W-16 oil produced an unexpected transition in the wear phenomenon and resulted in severe wear.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"29 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the most pressing questions today is how to prevent or slow down climate change. As a service sector, transport significantly contributes to this and increases greenhouse gas emissions. Furthermore, creating long-term sustainable social, economic and environmental processes by eliminating current systemic failures can also be a significant challenge for individual nations. One thing is sure: the status quo is not sustainable. Taking all these aspects into account, this paper seeks to answer the question of the extent to which the performance of freight transport in each EU Member State contributes to the change in the ecological footprint and how national characteristics influence this. The research introduces a newly established indicator, the freight transport footprint, which is based on a family of footprint formulas and specifically seeks to answer the extent to which freight transport burdens our environment.
{"title":"Environmental Impact of Freight Transport – Freight Footprint as a New Freight Transport Indicator","authors":"Adrienn Boldizsár","doi":"10.3311/pptr.23215","DOIUrl":"https://doi.org/10.3311/pptr.23215","url":null,"abstract":"One of the most pressing questions today is how to prevent or slow down climate change. As a service sector, transport significantly contributes to this and increases greenhouse gas emissions. Furthermore, creating long-term sustainable social, economic and environmental processes by eliminating current systemic failures can also be a significant challenge for individual nations. One thing is sure: the status quo is not sustainable. Taking all these aspects into account, this paper seeks to answer the question of the extent to which the performance of freight transport in each EU Member State contributes to the change in the ecological footprint and how national characteristics influence this. The research introduces a newly established indicator, the freight transport footprint, which is based on a family of footprint formulas and specifically seeks to answer the extent to which freight transport burdens our environment.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"1 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138978806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The pedestrian mode is gaining recognition as a basic building block in urban system design. Increasing attention is being given to developing vehicle-free zones to reduce urban pollution and return the inner city to its former role as a place for personal interaction. Attempts are being made to improve the walking experience, to make it more safe, convenient, and attractive especially in urban milieu to promote sustainable development. To provide the best pedestrian environment, it is necessary to understand pedestrian level of service. Conventional techniques of LOS determination consider the basic mobility characteristics of the pedestrian. The objective of this study is to develop a more accurate method of estimating level of service of pedestrians by developing composite indicators that integrate both qualitative and quantitative factors affecting both pedestrian and roadway conditions in the pedestrian movement. The relative importance of these multifaceted factors is assessed using Saaty scale and an Analytic Hierarchy Process is applied to determine the level of service. Field investigations include road network characterization and inventory studies, vehicular / pedestrian traffic characterization studies, pedestrian opinion surveys, expert opinion surveys. The approach has been applied to a major arterial road in Hyderabad city, Telangana, India in Mehdipatnam zone where pedestrian interactions are relatively high due to the commercial activity along the corridors. The stretches considered in the study exhibited Level of service "B" and "C" which implied necessary improvements to promote a good level of service.
步行模式作为城市系统设计的基本组成部分，正在得到越来越多的认可。人们越来越重视开发无车区，以减少城市污染，并使城市内部重新成为人际交往的场所。人们正试图改善步行体验，使其更加安全、方便和有吸引力，特别是在城市环境中，以促进可持续发展。为了提供最佳的步行环境，有必要了解行人服务水平。传统的 LOS 确定技术考虑的是行人的基本流动性特征。本研究的目的是通过开发综合指标来估算行人的服务水平，这些指标综合了影响行人和道路状况的定性和定量因素。这些多方面因素的相对重要性采用 Saaty 量表进行评估，并应用层次分析法确定服务水平。实地调查包括路网特征和清单研究、车辆/行人交通特征研究、行人意见调查和专家意见调查。该方法已应用于印度特兰格纳邦海得拉巴市 Mehdipatnam 区的一条主要干道，由于走廊沿线的商业活动，这里的行人互动相对较多。研究中考虑的路段的服务水平为 "B "和 "C"，这意味着需要进行必要的改进，以提高服务水平。
{"title":"Development of Composite Pedestrian Level of Service Model in Urban Milieu at Midblock Sections","authors":"Jayasree Kuchu","doi":"10.3311/pptr.20798","DOIUrl":"https://doi.org/10.3311/pptr.20798","url":null,"abstract":"The pedestrian mode is gaining recognition as a basic building block in urban system design. Increasing attention is being given to developing vehicle-free zones to reduce urban pollution and return the inner city to its former role as a place for personal interaction. Attempts are being made to improve the walking experience, to make it more safe, convenient, and attractive especially in urban milieu to promote sustainable development. To provide the best pedestrian environment, it is necessary to understand pedestrian level of service. Conventional techniques of LOS determination consider the basic mobility characteristics of the pedestrian. The objective of this study is to develop a more accurate method of estimating level of service of pedestrians by developing composite indicators that integrate both qualitative and quantitative factors affecting both pedestrian and roadway conditions in the pedestrian movement. The relative importance of these multifaceted factors is assessed using Saaty scale and an Analytic Hierarchy Process is applied to determine the level of service. Field investigations include road network characterization and inventory studies, vehicular / pedestrian traffic characterization studies, pedestrian opinion surveys, expert opinion surveys. The approach has been applied to a major arterial road in Hyderabad city, Telangana, India in Mehdipatnam zone where pedestrian interactions are relatively high due to the commercial activity along the corridors. The stretches considered in the study exhibited Level of service \"B\" and \"C\" which implied necessary improvements to promote a good level of service.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"19 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138981093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper two different turbulence models and wall treatment methods were investigated with Computational Fluid Dynamics (CFD) method. The used geometry for the research was the Ahmed body. The Ahmed body is a widely used geometry in vehicle aerodynamics investigations. The geometry represents a simplified vehicle, which allows the researchers to make examinations with moderate resources. The simulations were made in Ansys Fluent. The environment of the simulation was built to optimize for maximum 8 GB RAM. The paper examines the difference between the k-ω SST and the k-ε turbulence models in the case of low and high Reynolds number wall treatment methods. This could be useful because the high Reynolds number wall treatment method needs less computational capacity based on that, its required y+ range is between 30 and 300. While in the case of the low Reynolds wall treatment method the required y+ range is below 10, which could increase the cell count. The results from the CFD simulation will be compared to each other and with measured data. The aim of the research is to get information about behaviour of the examined turbulence models in the case of low and high Reynolds number wall treatment methods.
{"title":"Comparison of Different Turbulence Models and Wall Treatment Methods for Vehicle Aerodynamics Investigations","authors":"Brúnó Péter, István Lakatos","doi":"10.3311/pptr.22671","DOIUrl":"https://doi.org/10.3311/pptr.22671","url":null,"abstract":"In this paper two different turbulence models and wall treatment methods were investigated with Computational Fluid Dynamics (CFD) method. The used geometry for the research was the Ahmed body. The Ahmed body is a widely used geometry in vehicle aerodynamics investigations. The geometry represents a simplified vehicle, which allows the researchers to make examinations with moderate resources. The simulations were made in Ansys Fluent. The environment of the simulation was built to optimize for maximum 8 GB RAM. The paper examines the difference between the k-ω SST and the k-ε turbulence models in the case of low and high Reynolds number wall treatment methods. This could be useful because the high Reynolds number wall treatment method needs less computational capacity based on that, its required y+ range is between 30 and 300. While in the case of the low Reynolds wall treatment method the required y+ range is below 10, which could increase the cell count. The results from the CFD simulation will be compared to each other and with measured data. The aim of the research is to get information about behaviour of the examined turbulence models in the case of low and high Reynolds number wall treatment methods.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"13 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138980269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Road Safety has always been a factor of great concern in India as well as across the world. Road Traffic Accidents have been consistently increasing, and to address this issue, the world's governments declared 2021 to 2030 as the 'Decade of Action' for Road Safety. This rise in accidents can be attributed to the increasing motorization escalation, increasing individual modes of transport, soaring speeds, drinking and driving, increasing transportation network patterns and inefficient enforcement, to name a few. If compendiously scrutinized, the losses due to road traffic incidences are wholly avoidable. A comprehensive study was thus conducted to identify the key aspects which can be attributed to road safety. The six key factors were identified, namely the design of roads, the design of vehicles, the role of the law enforcement agency, the part of the Indian judicial system, the function of the Indian medical system, and general public awareness for developing road safety index. Primary data collection among various population segments identified the relative importance of these factors. The weightage based on the importance of these factors was computed using the Logarithmic Goal Programming Model, and thus, the Road Safety Index was developed.
{"title":"Exploratory Study for the Development of Road Safety Index on Indian Roads","authors":"Electricwala Fatima, L. Gupta, Rakesh Kumar","doi":"10.3311/pptr.22606","DOIUrl":"https://doi.org/10.3311/pptr.22606","url":null,"abstract":"Road Safety has always been a factor of great concern in India as well as across the world. Road Traffic Accidents have been consistently increasing, and to address this issue, the world's governments declared 2021 to 2030 as the 'Decade of Action' for Road Safety. This rise in accidents can be attributed to the increasing motorization escalation, increasing individual modes of transport, soaring speeds, drinking and driving, increasing transportation network patterns and inefficient enforcement, to name a few. If compendiously scrutinized, the losses due to road traffic incidences are wholly avoidable. A comprehensive study was thus conducted to identify the key aspects which can be attributed to road safety. The six key factors were identified, namely the design of roads, the design of vehicles, the role of the law enforcement agency, the part of the Indian judicial system, the function of the Indian medical system, and general public awareness for developing road safety index. Primary data collection among various population segments identified the relative importance of these factors. The weightage based on the importance of these factors was computed using the Logarithmic Goal Programming Model, and thus, the Road Safety Index was developed.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"77 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139210503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aim of this paper is to investigate the relationship between the number of extraordinary events and the total number of accidents and serious accidents in railway traffic. The purpose of the paper is to estimate the total number of accidents and serious accidents on the track network of Croatian Railway Infrastructure (HŽI) until 2027. The results of the research are based on secondary data that are the subject of processing using statistical methods of correlation and regression analysis. The main finding of this paper points to the existence of a strong and positive relationship between the number of extraordinary events and the total number of accidents and serious accidents in railway traffic. The estimated number of extraordinary events and total number of accidents and serious accidents until 2027 indicates a trend of their further reduction.
{"title":"An Estimate of the Number of Accidents and Serious Accidents in Railway Traffic","authors":"D. Pupavac, Anton Marinac, Josip Knežević","doi":"10.3311/pptr.21753","DOIUrl":"https://doi.org/10.3311/pptr.21753","url":null,"abstract":"The aim of this paper is to investigate the relationship between the number of extraordinary events and the total number of accidents and serious accidents in railway traffic. The purpose of the paper is to estimate the total number of accidents and serious accidents on the track network of Croatian Railway Infrastructure (HŽI) until 2027. The results of the research are based on secondary data that are the subject of processing using statistical methods of correlation and regression analysis. The main finding of this paper points to the existence of a strong and positive relationship between the number of extraordinary events and the total number of accidents and serious accidents in railway traffic. The estimated number of extraordinary events and total number of accidents and serious accidents until 2027 indicates a trend of their further reduction.","PeriodicalId":39536,"journal":{"name":"Periodica Polytechnica Transportation Engineering","volume":"183 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139212570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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