J. Braunfelds, K. Zvirbule, U. Seņkāns, R. Murnieks, I. Lyashuk, J. Porins, S. Spolitis, V. Bobrovs
Abstract Four-wave mixing optical frequency comb fibre-based setups (FWM-OFCs) have the potential to improve the combined dense wavelength division multiplexed passive optical network (DWDM-PON) and fibre Bragg grating (FBG) temperature sensors network providing easier application, broader technological opportunities for network development, and energy efficiency by substituting a power-demanding laser array. In this research, OFCs are generated for the purpose of combined network application of DWDM-PON and FBG optical sensors. The paper also investigates compatibility scenarios with OFCs in such systems. The mathematical simulation model has been developed and the performance of FWM-OFC based 8-channel 50 GHz spaced non-return-to-zero on-off keying (NRZ-OOK) modulated DWDM-PON transmission system, operating at 50 km single-mode fibre (SMF) with a bit rate of at least 10 Gbps embedded with 7 FBG optical temperature sensors, has been studied. As it is shown, FWM application results in OFC source that has fluctuations of the individual comb tones of less than 3 dB in power, and with an extinction ratio of about 33 dB for operation range of 192.9–193.25 THz, acting as a unified light source for all the data transmission channels. Embedded FBG optical sensors network causes negligible 0.3 dB power penalty.
{"title":"Application of FWM-Based OFC for DWDM Optical Communication System with Embedded FBG Sensor Network","authors":"J. Braunfelds, K. Zvirbule, U. Seņkāns, R. Murnieks, I. Lyashuk, J. Porins, S. Spolitis, V. Bobrovs","doi":"10.2478/lpts-2023-0025","DOIUrl":"https://doi.org/10.2478/lpts-2023-0025","url":null,"abstract":"Abstract Four-wave mixing optical frequency comb fibre-based setups (FWM-OFCs) have the potential to improve the combined dense wavelength division multiplexed passive optical network (DWDM-PON) and fibre Bragg grating (FBG) temperature sensors network providing easier application, broader technological opportunities for network development, and energy efficiency by substituting a power-demanding laser array. In this research, OFCs are generated for the purpose of combined network application of DWDM-PON and FBG optical sensors. The paper also investigates compatibility scenarios with OFCs in such systems. The mathematical simulation model has been developed and the performance of FWM-OFC based 8-channel 50 GHz spaced non-return-to-zero on-off keying (NRZ-OOK) modulated DWDM-PON transmission system, operating at 50 km single-mode fibre (SMF) with a bit rate of at least 10 Gbps embedded with 7 FBG optical temperature sensors, has been studied. As it is shown, FWM application results in OFC source that has fluctuations of the individual comb tones of less than 3 dB in power, and with an extinction ratio of about 33 dB for operation range of 192.9–193.25 THz, acting as a unified light source for all the data transmission channels. Embedded FBG optical sensors network causes negligible 0.3 dB power penalty.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"61 - 76"},"PeriodicalIF":0.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42578327","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}
J. Gutans, N. Mozga, V. Šestakovs, R. Kubulins, M. Kleinhofs
Abstract The article presents the results of the analysis of approaches to designing a mobile vacuum system for simulation of space environment, which could help provide services of testing space objects at the request of the customers at a place and time acceptable to them, which allows saving time and assets in the development of space objects, their elements, including satellites. Such a system under a conditional name METAMORPHOSIS is developed at Riga Technical University (RTU). As a result of the conducted analysis, the methodological approaches to the determination of the structure of the vacuum system were determined and a description of the main systems which should be included in the designed mobile simulator of space environment, as well as the methods for assessment of characteristics of its structural elements were given. The results obtained allow deciding on using a cylindrical vacuum chamber with a horizontal structure type for the designed simulator, since the weight of test equipment in this case is minimal, and determining its main dimensions, which are also specified in the article.
{"title":"Calculations of Basic Geometric Parameters for Mobile Space Environment Simulation Facility “Metamorphosis”","authors":"J. Gutans, N. Mozga, V. Šestakovs, R. Kubulins, M. Kleinhofs","doi":"10.2478/lpts-2023-0017","DOIUrl":"https://doi.org/10.2478/lpts-2023-0017","url":null,"abstract":"Abstract The article presents the results of the analysis of approaches to designing a mobile vacuum system for simulation of space environment, which could help provide services of testing space objects at the request of the customers at a place and time acceptable to them, which allows saving time and assets in the development of space objects, their elements, including satellites. Such a system under a conditional name METAMORPHOSIS is developed at Riga Technical University (RTU). As a result of the conducted analysis, the methodological approaches to the determination of the structure of the vacuum system were determined and a description of the main systems which should be included in the designed mobile simulator of space environment, as well as the methods for assessment of characteristics of its structural elements were given. The results obtained allow deciding on using a cylindrical vacuum chamber with a horizontal structure type for the designed simulator, since the weight of test equipment in this case is minimal, and determining its main dimensions, which are also specified in the article.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"54 - 68"},"PeriodicalIF":0.6,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46683342","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}
Abstract In this paper, we study by numerical simulation, the cooling of a solar photovoltaic panel using a nanofluid as a cooler. The solar panel is subjected to a hot temperature that character-ises the climate of the city of Bechar located in southwestern Algeria. The nanofluid (Al2O3-water) is introduced in the cavity with a constant horizontal speed and subjected to the ambient (cold) temperature. The equations governing the hydrodynamics of the flow and the heat transfer are described by the Navier-Stockes and energy equations. The finite element method is used to solve the system of partial differential equations (PDEs) based on the Galerkin method. We consider the effect of solid volume fraction and form factor for different values of Reynolds number on the results in the form of isotherms, streamlines, temperature, velocity, average Nusselt numbers and solar panel efficiency.
{"title":"Study of the Performance of a Photovoltaic Solar Panel by Using a Nanofluid as a Cooler","authors":"R. Abdeldjebar, M. Elmir, M. Douha","doi":"10.2478/lpts-2023-0018","DOIUrl":"https://doi.org/10.2478/lpts-2023-0018","url":null,"abstract":"Abstract In this paper, we study by numerical simulation, the cooling of a solar photovoltaic panel using a nanofluid as a cooler. The solar panel is subjected to a hot temperature that character-ises the climate of the city of Bechar located in southwestern Algeria. The nanofluid (Al2O3-water) is introduced in the cavity with a constant horizontal speed and subjected to the ambient (cold) temperature. The equations governing the hydrodynamics of the flow and the heat transfer are described by the Navier-Stockes and energy equations. The finite element method is used to solve the system of partial differential equations (PDEs) based on the Galerkin method. We consider the effect of solid volume fraction and form factor for different values of Reynolds number on the results in the form of isotherms, streamlines, temperature, velocity, average Nusselt numbers and solar panel efficiency.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"69 - 84"},"PeriodicalIF":0.6,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47100068","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}
Abstract On a global scale, the agriculture sector is a major contributor to greenhouse gas emissions, and this holds true for the European Union as well. While a shift to renewable energy sources could reduce reliance on fossil fuels and enable electrified agriculture, there are significant challenges to overcome. These include the high initial costs and inconsistent energy output of renewable sources, as well as issues with acceptance and cost related to electric tractor technology and load-balancing batteries. To explore potential solutions and future prospects for electrifying agriculture, a literature review is conducted to identify emerging technologies and research trends in areas such as agrovoltaics, semi-transparent photovoltaic panels, energy storage systems and electric tractors. The review conducted will provide a valuable insight into future research and the implementation of emerging technologies, thus addressing the challenges faced by the agriculture sector during its transition to electrification based on renewable energy sources.
{"title":"Agriculture Electrification, Emerging Technologies, Trends and Barriers: A Comprehensive Literature Review","authors":"J. Stakens, A. Mutule, R. Lazdins","doi":"10.2478/lpts-2023-0015","DOIUrl":"https://doi.org/10.2478/lpts-2023-0015","url":null,"abstract":"Abstract On a global scale, the agriculture sector is a major contributor to greenhouse gas emissions, and this holds true for the European Union as well. While a shift to renewable energy sources could reduce reliance on fossil fuels and enable electrified agriculture, there are significant challenges to overcome. These include the high initial costs and inconsistent energy output of renewable sources, as well as issues with acceptance and cost related to electric tractor technology and load-balancing batteries. To explore potential solutions and future prospects for electrifying agriculture, a literature review is conducted to identify emerging technologies and research trends in areas such as agrovoltaics, semi-transparent photovoltaic panels, energy storage systems and electric tractors. The review conducted will provide a valuable insight into future research and the implementation of emerging technologies, thus addressing the challenges faced by the agriculture sector during its transition to electrification based on renewable energy sources.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"18 - 32"},"PeriodicalIF":0.6,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42315994","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}
Abstract Since decarbonization of the energy sector is among the top priorities in the EU, with ambitious targets of carbon neutrality until 2050, the energy efficiency of the building stock and the use of renewables are those directions, which can bring the most considerable input towards the achievement of these goals. However, it is not always obvious how to efficiently combine different aspects of low energy demand, availability of renewables, part load operation conditions etc. The results of dynamic IDA ICE simulations highlight that the introduction of renewable low-carbon energy sources should be thoroughly coupled with building energy systems and only their full compatibility can give a high efficiency of the entire energy supply system of the building. Analysing simulation data, it was concluded that for low-energy buildings, heat pumps would not always show higher COP values, compared to buildings with higher energy demand. Ground source heat pump (GSHP) will not always be more efficient than air source heat pump (ASHP). If the ground/groundwater temperature is lower than 10 °C, for GSHP it will be almost impossible to over-compete ASHP within the same system. While COP with radiators and underfloor heating differs only by 10 %, both for ASHP and GSHP.
{"title":"Evaluation of Heat Pump Operation in a Single-Family House","authors":"A. Zajacs, K. Lebedeva, R. Bogdanovičs","doi":"10.2478/lpts-2023-0019","DOIUrl":"https://doi.org/10.2478/lpts-2023-0019","url":null,"abstract":"Abstract Since decarbonization of the energy sector is among the top priorities in the EU, with ambitious targets of carbon neutrality until 2050, the energy efficiency of the building stock and the use of renewables are those directions, which can bring the most considerable input towards the achievement of these goals. However, it is not always obvious how to efficiently combine different aspects of low energy demand, availability of renewables, part load operation conditions etc. The results of dynamic IDA ICE simulations highlight that the introduction of renewable low-carbon energy sources should be thoroughly coupled with building energy systems and only their full compatibility can give a high efficiency of the entire energy supply system of the building. Analysing simulation data, it was concluded that for low-energy buildings, heat pumps would not always show higher COP values, compared to buildings with higher energy demand. Ground source heat pump (GSHP) will not always be more efficient than air source heat pump (ASHP). If the ground/groundwater temperature is lower than 10 °C, for GSHP it will be almost impossible to over-compete ASHP within the same system. While COP with radiators and underfloor heating differs only by 10 %, both for ASHP and GSHP.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"85 - 98"},"PeriodicalIF":0.6,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48545136","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}
U. Seņkāns, J. Braunfelds, K. Rubuls, I. Murans, J. Porins, V. Bobrovs, S. Spolitis
Abstract As the demand for fiber optical data transmission systems and other type of applications, which require optical media, like optical sensing increases, the unauthorized parties are becoming increasingly interested in such systems. Also, with such demand, more complex optical systems are required; thus, the network infrastructure is becoming more crowded. It is vital to economize on the available resources and infrastructure to ensure the needs of all interested business, governmental or end-user sides. Therefore, the present research focuses on the development of a unified hybrid optical system. The developed hybrid optical transmission system adds additional protection to the channels, allows for the unification of standard optical data transmission channels, optical sensors and spectrally hidden data transmission channel systems, and increases the efficiency of the optical components used.
{"title":"Development of Unified Hybrid WDM-PON With Spectrally Hidden Data Channel System and FBG Optical Sensor Network","authors":"U. Seņkāns, J. Braunfelds, K. Rubuls, I. Murans, J. Porins, V. Bobrovs, S. Spolitis","doi":"10.2478/lpts-2023-0020","DOIUrl":"https://doi.org/10.2478/lpts-2023-0020","url":null,"abstract":"Abstract As the demand for fiber optical data transmission systems and other type of applications, which require optical media, like optical sensing increases, the unauthorized parties are becoming increasingly interested in such systems. Also, with such demand, more complex optical systems are required; thus, the network infrastructure is becoming more crowded. It is vital to economize on the available resources and infrastructure to ensure the needs of all interested business, governmental or end-user sides. Therefore, the present research focuses on the development of a unified hybrid optical system. The developed hybrid optical transmission system adds additional protection to the channels, allows for the unification of standard optical data transmission channels, optical sensors and spectrally hidden data transmission channel systems, and increases the efficiency of the optical components used.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"99 - 103"},"PeriodicalIF":0.6,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42141012","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}
O. Linkevičs, E. Vesperis, K. Gičevskis, V. Osadcuks, A. Pecka, A. Galiņš
Abstract Autonomous off-grid systems might be seen as a favourable option when it comes to high grid connection fees and for a sustainable electric system in transition to a low-carbon, renewable-based decentralized system. To ensure such a system, accurate analysis of different scenarios is required to determine the optimal energy source mix and sizing of the off-grid system. Software computing techniques or mathematical models can help solve this task, but, unfortunately, it is unpredictable how actually such systems will perform in real life. There are not so many publications, where the real data and off-grid systems are analysed and compared to simulation results. Thus, this paper examines an experimental stand-alone electrical off-grid solution in Latvia. The operational data of real autonomous off-grid system are obtained for the off-grid system performance and control strategy analysis, which is highly relevant for the planning and dimensioning of affordable renewable off-grid systems.
{"title":"Analysis of Experimental Data from Household Off-Grid System in Latvia","authors":"O. Linkevičs, E. Vesperis, K. Gičevskis, V. Osadcuks, A. Pecka, A. Galiņš","doi":"10.2478/lpts-2023-0014","DOIUrl":"https://doi.org/10.2478/lpts-2023-0014","url":null,"abstract":"Abstract Autonomous off-grid systems might be seen as a favourable option when it comes to high grid connection fees and for a sustainable electric system in transition to a low-carbon, renewable-based decentralized system. To ensure such a system, accurate analysis of different scenarios is required to determine the optimal energy source mix and sizing of the off-grid system. Software computing techniques or mathematical models can help solve this task, but, unfortunately, it is unpredictable how actually such systems will perform in real life. There are not so many publications, where the real data and off-grid systems are analysed and compared to simulation results. Thus, this paper examines an experimental stand-alone electrical off-grid solution in Latvia. The operational data of real autonomous off-grid system are obtained for the off-grid system performance and control strategy analysis, which is highly relevant for the planning and dimensioning of affordable renewable off-grid systems.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"3 - 17"},"PeriodicalIF":0.6,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49319437","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}
L. Zemite, A. Backurs, A. Starikovs, A. Laizāns, L. Jansons, L. Vempere, I. Bode, A. Broks
Abstract Hydrogen has been widely recognised as a versatile and environmentally-friendly energy carrier, with a broad range of potential applications across various sectors. The abundance of hydrogen in the universe and its high energy content makes it an attractive alternative to conventional fossil fuels. Moreover, the utilization of hydrogen does not produce greenhouse gases or other pollutants that contribute to air pollution and climate change. In recent years, there has been a growing interest in developing and deploying hydrogen technologies for a sustainable energy future. This paper provides an in-depth exploration of the potential of hydrogen as a clean energy source in different sectors, such as transportation, energy storage, power generation, industry, buildings, maritime transport, and aviation. The aim of the paper is to provide an overview of the current state of hydrogen applications in Europe and the Baltic States, including examples of ongoing projects and initiatives, and to assess the advantages and disadvantages of hydrogen technologies in different sectors. The main results of the paper highlight that hydrogen has the potential to significantly reduce greenhouse gas emissions and achieve carbon neutrality targets. However, the deployment of hydrogen technologies also faces various challenges such as high production costs, lack of infrastructure, and safety concerns. The tasks of the paper are to provide an insight into the potential of hydrogen, identify the challenges and limitations, and highlight ongoing research and development efforts in this field. The paper concludes that the widespread adoption of hydrogen technologies is a long-term goal that requires the cooperation of various stakeholders and the development of innovative and cost-effective solutions. Despite the challenges, the current state of hydrogen applications and ongoing projects in Europe and the Baltic States demonstrate that hydrogen has the potential to play a significant role in the transition to a sustainable and low-carbon future.
{"title":"A Comprehensive Overview of the Europen and Baltic Landscape for Hydrogen Applications and Innovations","authors":"L. Zemite, A. Backurs, A. Starikovs, A. Laizāns, L. Jansons, L. Vempere, I. Bode, A. Broks","doi":"10.2478/lpts-2023-0016","DOIUrl":"https://doi.org/10.2478/lpts-2023-0016","url":null,"abstract":"Abstract Hydrogen has been widely recognised as a versatile and environmentally-friendly energy carrier, with a broad range of potential applications across various sectors. The abundance of hydrogen in the universe and its high energy content makes it an attractive alternative to conventional fossil fuels. Moreover, the utilization of hydrogen does not produce greenhouse gases or other pollutants that contribute to air pollution and climate change. In recent years, there has been a growing interest in developing and deploying hydrogen technologies for a sustainable energy future. This paper provides an in-depth exploration of the potential of hydrogen as a clean energy source in different sectors, such as transportation, energy storage, power generation, industry, buildings, maritime transport, and aviation. The aim of the paper is to provide an overview of the current state of hydrogen applications in Europe and the Baltic States, including examples of ongoing projects and initiatives, and to assess the advantages and disadvantages of hydrogen technologies in different sectors. The main results of the paper highlight that hydrogen has the potential to significantly reduce greenhouse gas emissions and achieve carbon neutrality targets. However, the deployment of hydrogen technologies also faces various challenges such as high production costs, lack of infrastructure, and safety concerns. The tasks of the paper are to provide an insight into the potential of hydrogen, identify the challenges and limitations, and highlight ongoing research and development efforts in this field. The paper concludes that the widespread adoption of hydrogen technologies is a long-term goal that requires the cooperation of various stakeholders and the development of innovative and cost-effective solutions. Despite the challenges, the current state of hydrogen applications and ongoing projects in Europe and the Baltic States demonstrate that hydrogen has the potential to play a significant role in the transition to a sustainable and low-carbon future.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"33 - 53"},"PeriodicalIF":0.6,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43658873","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}
Abstract In this paper a ventilation element is designed with the constant cross-sectional area of 3.14 mm2 with the outer ring, to study the efficiency of ventilation at three different inlet air velocities (2, 5 and 8 m/s). There are five different cases analysed in the study, in which four cases are with different coordinate values of outer ring and core while the fifth case is studied with ventilation element without outer ring. The results of all five cases are analysed and compared to see the efficiency of ventilation element design. These ventilation elements are attached at ventilation hole at the inner part of the protective jacket. The attached ventilation element increases mechanical strength of the clothing by covering ventilation hole and restricting direct access of insects to the body. Moreover, ventilation elements permit smooth flow of air inside jacket. The objective is to determine which element’s geometrical configuration results in the minimum flow energy losses in the cell flow channel from the inlet to the outlet, which are represented by the pressure difference. Flow energy losses increase with increasing pressure difference (ΔP), and the body cooling reduces if the flow is weakened or there is of lost energy. SolidWorks Flow Simulation is used to calculate the pressure, temperature, and heat flux for the simplified elliptical model of the human body with a protective jacket. The obtained results are compared and analysed to study the concept of constant cross-sectional area in the design of ventilation elements with and without outer ring. The pressure and temperature difference for each case are calculated for the comparison and the obtained results show that the element design without outer ring provides better overall results and less flow energy loss in the cell flow channel than that of element design with outer ring.
{"title":"Air Flow Analysis for Protective Clothing Ventilation Elements with and Without Constant Cross-Section Area Opening","authors":"A. Janushevskis, S. Vejanand, A. Gulevskis","doi":"10.2478/lpts-2023-0012","DOIUrl":"https://doi.org/10.2478/lpts-2023-0012","url":null,"abstract":"Abstract In this paper a ventilation element is designed with the constant cross-sectional area of 3.14 mm2 with the outer ring, to study the efficiency of ventilation at three different inlet air velocities (2, 5 and 8 m/s). There are five different cases analysed in the study, in which four cases are with different coordinate values of outer ring and core while the fifth case is studied with ventilation element without outer ring. The results of all five cases are analysed and compared to see the efficiency of ventilation element design. These ventilation elements are attached at ventilation hole at the inner part of the protective jacket. The attached ventilation element increases mechanical strength of the clothing by covering ventilation hole and restricting direct access of insects to the body. Moreover, ventilation elements permit smooth flow of air inside jacket. The objective is to determine which element’s geometrical configuration results in the minimum flow energy losses in the cell flow channel from the inlet to the outlet, which are represented by the pressure difference. Flow energy losses increase with increasing pressure difference (ΔP), and the body cooling reduces if the flow is weakened or there is of lost energy. SolidWorks Flow Simulation is used to calculate the pressure, temperature, and heat flux for the simplified elliptical model of the human body with a protective jacket. The obtained results are compared and analysed to study the concept of constant cross-sectional area in the design of ventilation elements with and without outer ring. The pressure and temperature difference for each case are calculated for the comparison and the obtained results show that the element design without outer ring provides better overall results and less flow energy loss in the cell flow channel than that of element design with outer ring.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"63 - 73"},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45813305","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}
Abstract Recent interest of solar physicists in the analysis of the coronal mass ejections and circular solar flares in fan-spine magnetic configurations (FSCs) necessitates measurements of the corresponding coronal magnetic fields. A dominant sunspot with the circumjacent magnetic flux of opposite polarity produces a specific coronal region of the quasi-transverse (QT-) propagation of microwaves. We make use of the theory of QT-propagation to evaluate the strengths of coronal magnetic fields in the active regions NOAA 11579, 12242, and 12488 while they are non-flaring. Microwave polarization changes were observed with the RATAN-600 radio telescope, the Siberian Solar Radio Telescope, and the Nobeyama Radioheliograph. Changes in the sign of circular radio polarization provide the strengths of coronal fields in a QT-region if the coronal plasma density Ne and the length scale of magnetic field divergence Ld are known. We evaluate the length scale by means of the potential-field source-surface (PFSS) model and the coronal density from the Gaussian inversion of the differential emission measure (from the Solar Dynamics Observatory observational data), obtaining Ne Ld = (0.46–0.64)×1010 m−2. The resulting coronal fields of 1.4×10−3 T and 2.34×10−3 T are attributed to the heights of 100 Mm and 50.2 Mm. We discuss the validity and consistency of the involved values to draw conclusions on the feasibility of coronal radio magnetography of FSCs.
{"title":"Radio Measurements of Coronal Magnetic Fields in Fan-Spine Configurations on the Sun","authors":"B. Ryabov, A. Vrublevskis","doi":"10.2478/lpts-2023-0011","DOIUrl":"https://doi.org/10.2478/lpts-2023-0011","url":null,"abstract":"Abstract Recent interest of solar physicists in the analysis of the coronal mass ejections and circular solar flares in fan-spine magnetic configurations (FSCs) necessitates measurements of the corresponding coronal magnetic fields. A dominant sunspot with the circumjacent magnetic flux of opposite polarity produces a specific coronal region of the quasi-transverse (QT-) propagation of microwaves. We make use of the theory of QT-propagation to evaluate the strengths of coronal magnetic fields in the active regions NOAA 11579, 12242, and 12488 while they are non-flaring. Microwave polarization changes were observed with the RATAN-600 radio telescope, the Siberian Solar Radio Telescope, and the Nobeyama Radioheliograph. Changes in the sign of circular radio polarization provide the strengths of coronal fields in a QT-region if the coronal plasma density Ne and the length scale of magnetic field divergence Ld are known. We evaluate the length scale by means of the potential-field source-surface (PFSS) model and the coronal density from the Gaussian inversion of the differential emission measure (from the Solar Dynamics Observatory observational data), obtaining Ne Ld = (0.46–0.64)×1010 m−2. The resulting coronal fields of 1.4×10−3 T and 2.34×10−3 T are attributed to the heights of 100 Mm and 50.2 Mm. We discuss the validity and consistency of the involved values to draw conclusions on the feasibility of coronal radio magnetography of FSCs.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"60 1","pages":"52 - 62"},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41621483","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：