Periodica Polytechnica Mechanical Engineering最新文献

Assessment of Simultaneous Heating Demands for Consumer Groups 消费者群体同时供暖需求评估

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-08-08 DOI: 10.3311/ppme.36546

L. Garbai, Róbert Sánta, Viktor Zónai

引用次数: 0

Investigation of the Replication Quality of Microstructures on Injection Moulded Specimens Made from Recycled Polypropylene Composites Reinforced with Carbon Nanotubes 碳纳米管增强再生聚丙烯复合材料注塑试样微观结构复制质量的研究

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-07-22 DOI: 10.3311/ppme.37288

Krisztián Kun, Attila Bata, F. Ronkay

引用次数: 0

New Dimensionless Power Number Equation for Horizontal Agitated Drum 水平搅拌鼓的新无量纲功率数方程

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-07-18 DOI: 10.3311/ppme.37286

Dániel Horváth, T. Poós

引用次数: 0

Oscillatory Potential-based Characterization of the Human Light-adapted Electroretinogram Using Discrete Wavelet Transform 利用离散小波变换对基于振荡电位的人类光适应视网膜电图进行表征

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-07-13 DOI: 10.3311/ppme.23845

Min Gao, M. Barboni, Viktória Szabó, Zoltán Zsolt Nagy, D. Zobor, Balázs Vince Nagy

{"title":"Oscillatory Potential-based Characterization of the Human Light-adapted Electroretinogram Using Discrete Wavelet Transform","authors":"Min Gao, M. Barboni, Viktória Szabó, Zoltán Zsolt Nagy, D. Zobor, Balázs Vince Nagy","doi":"10.3311/ppme.23845","DOIUrl":"https://doi.org/10.3311/ppme.23845","url":null,"abstract":"Purpose: Our aim was to apply multiple discrete wavelet transformation (DWT) types to healthy light-adapted (cone) electroretinogram (ERG) signals in order to optimize DWT analysy in ERG. Oscillatory potentials (OP) were individually extracted from the signals and used to calculate an indicator for ERG analysis.Methods: Light-adapted (LA) 3.0 cd.s/m2 ISCEV standard ERGs were recorded from both eyes of 15 healthy volunteers (mean age: 36.9 ± 13.0 years old; 13 females). LA ERG signal components, such as b-wave and OPs, were analyzed using the discrete wavelet transformation (DWT). An index (%OPi) was proposed to estimate the individual oscillatory potentials (OP1-OP5) by calculating the coefficient ratio of the OP to b-wave. Multiple mother wavelet functions (i.e., Daubechies, Symlet, and Coiflet) with five orders were applied and compared statistically using Wilcoxon tests and paired t-test comparisons with Bonferroni posthoc analyses (p < 0.005). Results: OP4 shows the most energy at both low and high-frequency bands (80Hz and 160Hz), while OP2 has lower energy at the low-frequency band (80Hz) and higher energy at the high-frequency band (160Hz). The %OP2 is the largest among the five individual OPs. %OPs obtained with different wavelet functions differ from each other. Db2 and sym2 seem to be the optimal wavelets for analyzing light-adapted ERG components.Conclusion: Individual OPs of the light-adapted ERG obtained with the DWT analysis may characterize different levels of retinal dysfunction. The %OPi may serve as an indicator in ERG analysis.","PeriodicalId":513310,"journal":{"name":"Periodica Polytechnica Mechanical Engineering","volume":"29 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141650987","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}

引用次数: 0

Boundary Condition Options for Carotid Bifurcation Analysis, Using Doppler Velocity Measurements 利用多普勒速度测量进行颈动脉分叉分析的边界条件选项

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-05-21 DOI: 10.3311/ppme.28797

Márton Bence Németh, B. Csippa, Zsuzsa Mihály, György Paál, Péter Sótonyi

{"title":"Boundary Condition Options for Carotid Bifurcation Analysis, Using Doppler Velocity Measurements","authors":"Márton Bence Németh, B. Csippa, Zsuzsa Mihály, György Paál, Péter Sótonyi","doi":"10.3311/ppme.28797","DOIUrl":"https://doi.org/10.3311/ppme.28797","url":null,"abstract":"The Common Carotid Artery plays a vital role in supplying the brain, and its bifurcation is susceptible to vascular diseases. It is often analyzed using computational fluid dynamics (CFD) simulations, but it is challenging to prescribe boundary conditions that approach patient-specific flow conditions. We examined six boundary condition (BC) groups to determine the most accurate flow conditions aligning with available measured data. We conducted CFD simulations on a stenotic carotid bifurcation, using patient-specific Doppler ultrasound sonography velocity measurements at the inlet and both outlets. Three BC methods used defined inlet flow rate and either constant pressure (Basic), Windkessel model, or constant flow ratio (Murray) at the outlets. Three other methods were defined with flow rates at two boundaries and constant pressure at the third one. Defining two boundary flow rates shows the closest results to physiologically valid data. However, the difficult Doppler measurements on the outlet branches can inaccurately amplify velocity amplitudes and may detect a false flow direction. Therefore, cross-sectional corrections were implemented to fit the outlet and inlet flow rates, while keeping the measured velocity histories.Our results show that the Murray and Basic methods, while easily available, exclude carotid-specific flow conditions by disregarding downstream flow resistances. We conclude that a Windkessel-method can produce the most accurate results without forcing outflow conditions. However, usually unavailable measurements are necessary for its application. Simulations with outlet-defined volume flow can also produce physiologically valid solutions but require the application of cross-sectional geometry correction.","PeriodicalId":513310,"journal":{"name":"Periodica Polytechnica Mechanical Engineering","volume":"28 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141117245","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}

引用次数: 0

Heat Characteristics and Emission Effect of a Fuel-operated Auxiliary Air Heater Fed with Fuel E10, E30 and E100 使用 E10、E30 和 E100 燃料的燃油辅助空气加热器的热特性和排放效应

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-05-13 DOI: 10.3311/ppme.36911

P. Nagy, I. Zsoldos, György Szabados

{"title":"Heat Characteristics and Emission Effect of a Fuel-operated Auxiliary Air Heater Fed with Fuel E10, E30 and E100","authors":"P. Nagy, I. Zsoldos, György Szabados","doi":"10.3311/ppme.36911","DOIUrl":"https://doi.org/10.3311/ppme.36911","url":null,"abstract":"In order to increase the comfort of vehicle passengers in specific vehicle categories, the heating of the passenger compartment is not provided by the heat from the engine driving the vehicle but by an additional heating device. The study examines the effect of auxiliary heaters that use liquid fuels to heat the passenger compartment of vehicles. The device was operated during the test with two different mixtures containing bioethanol (E30, E100) and the original motor gasoline (E10). It aimed to understand the effects of different fuels, particularly heating performance, operating time and emissions. Based on the results, as the ethanol content increases, the temperature of the device’s flame and heating air decreases. The experiments showed that in the case of E100 bioethanol, the average temperature measured in stable operating conditions was significantly lower than in the case of E10 motor gasoline. That suggests that an increase in the ethanol content reduces the heating performance. Another significant result of the study was that in the case of mixtures containing ethanol, a longer operating time is required to achieve the same amount of heat, which leads to additional fuel consumption. In addition, when using E100 bioethanol, the amount of harmful gases that are emitted increases significantly during the longer operating time. This observation can be important for evaluating the environmental impact and efficiency of vehicles.","PeriodicalId":513310,"journal":{"name":"Periodica Polytechnica Mechanical Engineering","volume":"1 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140982580","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}

引用次数: 0

Evaluation of Viscoelastic Performance and Molecular Structures of Natural Rubber/NBR Blends Reinforced by Carbon Black and Nano-Silica 碳黑和纳米二氧化硅增强天然橡胶/丁腈橡胶共混物的粘弹性能和分子结构评估

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-05-13 DOI: 10.3311/ppme.28792

Amel Chelli, H. Mechakra, A. Chellil, D. Tria, Wissam Bessa, K. Ikkache, Brahim Safi

{"title":"Evaluation of Viscoelastic Performance and Molecular Structures of Natural Rubber/NBR Blends Reinforced by Carbon Black and Nano-Silica","authors":"Amel Chelli, H. Mechakra, A. Chellil, D. Tria, Wissam Bessa, K. Ikkache, Brahim Safi","doi":"10.3311/ppme.28792","DOIUrl":"https://doi.org/10.3311/ppme.28792","url":null,"abstract":"This study focuses on the evaluation of the dynamic mechanical properties, molecular structure, density, hardness, swelling behavior of natural rubber blends (NR) and nitrile rubber (NBR) reinforced with carbon black and/or nano-silica. An experimental work has been conducted to study of the effects of increasing NR content and incorporating nano-silica on the mechanical properties and molecular structure were studied using dynamic mechanical analysis (DMA) and Fourier transform infrared (FTIR) spectroscopy. The results show that increasing the NR content and/or incorporating nano-silica into the elastomer leads to a higher storage modulus with no significant change in the glass transition temperature. FTIR analysis indicates the compatibility of the polyblends and the presence of oxidation of the main polymer chain generated during the grinding of the rubber. Additionally, the results of the swelling study demonstrate that stronger molecular interactions occur on the surface of the nano-silica between the nitrile radicals in the NBR and the silanol (Si-OH) radicals. These findings suggest that blending NR and NBR with carbon black and/or nano-silica can improve the mechanical properties and compatibility of the resulting polyblends, with potential applications in the development of advanced elastomeric materials.","PeriodicalId":513310,"journal":{"name":"Periodica Polytechnica Mechanical Engineering","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140983926","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}

引用次数: 0

An Escalation System for Handling and Analyzing Production Disturbances 处理和分析生产干扰的升级系统

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-05-13 DOI: 10.3311/ppme.23004

István Gödri

引用次数: 0

Mechanical Characterization of Hybrid Bagasse/Eggshell/E-glass Fiber-based Polyester Composite 基于甘蔗渣/埃格斯贝/玻璃纤维的混合聚酯复合材料的机械特性分析

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-05-13 DOI: 10.3311/ppme.22963

D. N. Trivedi, Fiona Munezero, N. Rachchh

{"title":"Mechanical Characterization of Hybrid Bagasse/Eggshell/E-glass Fiber-based Polyester Composite","authors":"D. N. Trivedi, Fiona Munezero, N. Rachchh","doi":"10.3311/ppme.22963","DOIUrl":"https://doi.org/10.3311/ppme.22963","url":null,"abstract":"Currently, numerous researchers, scientists, and industrialists are drawn towards utilizing natural fillers rather than synthetic ones because of their environmentally-friendly characteristics, lower density per unit volume and favorable mechanical attributes. Several studies have demonstrated that using organic filler in polyester matrix composites, instead of disposing of them in landfills, has various advantages. The current study focuses on the investigation of the mechanical characteristics of composite material made from a combination of bagasse, eggshell, and e-glass fibers exhibit characteristics such as strength under tension, strength under bending, resistance to indentation, and mass per unit volume. Different weight percentages of eggshell/bagasse were used to make the material using the hand lay-up technique (3wt%, 6wt%, 9wt%, and 12wt%), with 19wt% of glass fiber mixed in the resin. The use of inorganic fillers like calcium carbonate, a non-renewable mineral that may be expensive and environmentally hazardous to extract and process, is being reduced in favor of organic fillers like eggshell and bagasse, which are inexpensive and readily available. Specimens were generated by interposing fiber waste amidst chopped strand glass fiber mats, with variations in the bagasse, eggshell and polyester content, while keeping the amount of E-glass fiber constant. Afterward, the specimens were trimmed to the appropriate dimensions and subjected to analysis with a universal apparatus. The research showed that enhancing the quantity of bagasse/eggshell fiber within the hybrid composite resulted in an enhancement of its mechanical characteristics. The best reinforcement effect was observed in a hybrid composite with 6% bagasse/eggshell fiber.","PeriodicalId":513310,"journal":{"name":"Periodica Polytechnica Mechanical Engineering","volume":"24 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140984227","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}

引用次数: 0

Numerical Investigation on Influence of Grooves on Tube Hydroforming Process of Aluminium Alloys 沟槽对铝合金管材水压成型工艺影响的数值研究

Periodica Polytechnica Mechanical Engineering Pub Date : 2024-04-19 DOI: 10.3311/ppme.20880

Ajith Ramesh, Ganesh Laxman Ramanathan, Arun Achuthankutty

{"title":"Numerical Investigation on Influence of Grooves on Tube Hydroforming Process of Aluminium Alloys","authors":"Ajith Ramesh, Ganesh Laxman Ramanathan, Arun Achuthankutty","doi":"10.3311/ppme.20880","DOIUrl":"https://doi.org/10.3311/ppme.20880","url":null,"abstract":"For several decades, scientists and engineers have been using the tube hydroforming (THF) process for numerous applications in the automotive and aerospace industries. The inert advantages like weight reduction without compromising on strength, improved part quality, better surface finish, and reduced tooling costs have motivated the use of THF in the fabrication industry. The presence of grooves on the pre-forms was found to immensely help in increasing the pressure-withstanding capacity of the THF tubes, in addition to reducing the stress concentration and achieving the near-net shape during the THF process. This project involves the development of a detailed Finite Element Model, for the THF process. Numerical analysis is carried out in two stages: Stage-1: Groove Formation, and Stage-2: Final THF tube formation. In Stage 1, the numerical model investigates the formation of grooves, predicting the amount of internal pressure and axial feeding that are required to accurately form them. In Stage 2, numerical simulations focus on the actual THF process. This two-stage THF process (Grooved-THF) was compared to a single-stage Generic THF process. The results indicate the Grooved-THF to be producing a relatively lower thickness reduction with a more closely formed corner radius compared to the generic case. The work also involves multi-objective optimization of the process parameters like the number of grooves, coefficient of friction, internal fluid pressure, and die corner radius using the DOE technique – RSM. The results indicate the number of grooves and the friction coefficient to be the most influencing parameters in the THF process.","PeriodicalId":513310,"journal":{"name":"Periodica Polytechnica Mechanical Engineering","volume":" 65","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140683116","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}

引用次数: 0