Latvian Journal of Physics and Technical Sciences最新文献

{"title":"Development of the District Heating System on the Left Bank of the Daugava River in Riga","authors":"E. Dzelzītis, N. Talcis, I. Pilmanis, I. Bode, L. Jansons, L. Zemite","doi":"10.2478/lpts-2022-0015","DOIUrl":"https://doi.org/10.2478/lpts-2022-0015","url":null,"abstract":"Abstract In Latvia, heat supply is provided in three different ways: using district heating (hereinafter – DH), local heating and individual heating systems. Heat energy consumption consists of heat energy consumption for heating, hot water and heat energy technological processes. The structure of DH consumers has not changed in recent years and the largest consumers of heat are households – 70 % of the total energy consumption. The district heating system accounts for approximately 29 % of the total consumption. There is also the so-called tertiary sector, which is made of municipal and state buildings with a minor total heat consumption of about 1 %. It should be noted that 65–70 % of energy is used for heating needs, and 30–35% for hot water preparation. In Latvia, heat of DH consumers is produced both in boiler houses (hereinafter – BHs) and cogeneration plants (hereinafter – CHPs). The latter also produce electricity. Over the past 10 years, the distribution of heat produced in BHs and CHPs has changed significantly. The heat supply of the Latvian energy sector is a system consisting of three main elements – heat source, transmission and distribution networks, and end consumer. Low efficiency of heat supply system elements creates risks to security of heat supply, resource sustainability and competitiveness. Increasing energy efficiency in the system as a whole, or in individual elements of the system, will promote the enhancement of the heat supply sector, while promoting economic growth as well. The research attempts to evaluate the energy efficiency of DH systems in the so-called left bank (hereinafter – LB) DH area (located on the left bank of the Daugava River in Riga).","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"128 - 139"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48364847","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}

{"title":"Technological Assurance of Ti-6Al-4V Parts Produced by Additive Manufacturing Using Selective Metal Laser Sintering","authors":"A. Kromanis, A. Vevers","doi":"10.2478/lpts-2022-0018","DOIUrl":"https://doi.org/10.2478/lpts-2022-0018","url":null,"abstract":"Abstract The research relates to a technological assurance of Ti6-Al-4V parts produced by additive manufacturing (AM) by means of a metal laser sintering, especially by a fibre laser 3D printer. The influence of technological parameters such as layer thickness, hatch spacing, laser travel speed and laser power have been analysed as well as the influence of thermal treatment as a post processing method has been studied. Technological parameters in combination with a thermal treatment present a challenge in order to manufacture satisfactory products in terms of mechanical properties. The research guides through different phases of experiments to distinguish the best technological parameters. The following research may be used for further investigation of technological assurance for additive manufacturable parts as well as forms the springboard for further research in development of new titanium composites using additive manufacturing methods.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"170 - 179"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45076129","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}

{"title":"Relationship Between Solar Millimeter and Soft X-Ray Emissions","authors":"J. Kallunki, M. Tornikoski","doi":"10.2478/lpts-2022-0023","DOIUrl":"https://doi.org/10.2478/lpts-2022-0023","url":null,"abstract":"Abstract The connection between solar radio and soft X-ray emission has earlier been studied at various radio frequencies. For instance, the intensity peak times during solar flares have been compared between these two wavelength regimes. It has been reported that solar radio emission peaks before soft X-ray emission during a flare. However, opposite results have also been presented. In this study, we compare millimetre (8 mm) solar and soft X-ray emissions (0.5–4 Å and 1–8 Å). The radio observations were made at Metsähovi Radio Observatory of Aalto University in Finland between 2015 and 2019. The soft X-ray data were observed with GOES-15 (Geostationary Operational Environmental Satellite). The data show that the solar millimetre emission can peak either before or after soft X-ray peak emission. In this study, we present two different scenarios, which could explain the peaking time differences and behaviour. The first scenario proposes a tight connection between the millimetre (8 mm) and soft X-ray emissions, the second one is for cases where the emission mechanisms are more separate.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"39 - 47"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48403427","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}

{"title":"The Study of Properties of an Axial Flux Switching Permanent Magnet Alternator with Open Magnetic Cores","authors":"V. Bezrukovs, V. Bezrukovs, M. Konuhova, D. Bezrukovs, A. Berzins","doi":"10.2478/lpts-2022-0026","DOIUrl":"https://doi.org/10.2478/lpts-2022-0026","url":null,"abstract":"Abstract The article studies magnetic field distribution in the alternator inductors with an axial arrangement of open magnetic cores (OMC) and an external closure of the magnetic flux. The study compares the efficiency of magnetic flux utilization for four models with different modifications of the geometry of the magnetic circuit of inductors. The analysis of the density distribution of magnetic flux in OMC is carried out by 3D modelling of the magnetic field using EMWorks software. Based on the experimental study of the properties of the base model, the influence of the configuration of the magnetic circuit of the inductor on the efficiency of the alternator is shown. The results are presented in the form of tables and diagrams characterising changes in magnetic fluxes and electromotive force (EMF) in relative units. The results provide the grounds for assessing the potential and possible limits of optimization with respect to the size of air gaps and dimensions of the magnetic flux toggle switches. The study indicates that the proposed alternator can be adapted for various load requirements and optimized for various applications, such as charging power banks and powering bicycle electronics. The study also demonstrates that for such generators, OMC can be manufactured using a waste-free strip production technology.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"69 - 81"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43355152","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}

{"title":"Hydrogen Hydraulic Compression System for Refuelling Stations","authors":"V. Bezrukovs, V. Bezrukovs, M. Konuhova, D. Bezrukovs, A. Berzins","doi":"10.2478/lpts-2022-0028","DOIUrl":"https://doi.org/10.2478/lpts-2022-0028","url":null,"abstract":"Abstract The article investigates the properties and potential of compressed hydrogen as one of the most promising energy carriers in order to facilitate the development of energy storage capabilities and lay down a stable foundation for the future of a sustainable energy sector. The study considers the use of hydrogen, compressed at high pressure from 50 MPa to 100 MPa, at refuelling stations to supply electric cars. The technical properties of modern hydraulic compressors used for hydrogen accumulation in high pressure buffer containers are considered. The study shows that the design of hydraulic compressors in terms of their technical characteristics optimally corresponds to the primary requirements for their use as booster compressors at refuelling stations. The authors conclude with the proposal of an enhanced design of the hydraulic compressor with the use of fluid flow counters in a control system of a hydrogen compression cycle. The proposed technical solution provides for continuous monitoring of the hydrogen compression process that increases the reliability of control system operation.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"96 - 105"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49336578","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}

{"title":"On the Issue of Collision of Balls in an Auto-Balancing Device","authors":"G. Strautmanis, I. Schukin, G. Filimonikhin, M. Mezitis, I. Kurjanovičs, I. Irbe","doi":"10.2478/lpts-2022-0016","DOIUrl":"https://doi.org/10.2478/lpts-2022-0016","url":null,"abstract":"Abstract The paper considers a model of a vertical double pendulum, which includes two balls suspended on rigid non-deformable threads to one centre of the suspension. For the proposed system of pendulums, differential equations of motion and conditions for collision of balls have been recorded. When simulating the motion of the pendulums, the central collision of the balls has been considered for various options of the motion of the suspension point: the suspension point is motionless; the suspension point oscillates in the vertical direction; the suspension point makes rotational motions in the vertical plane. Meanwhile, various conditions for the central collision between the balls have been considered: a perfectly inelastic collision; a perfectly elastic collision; a collision with transformation of collision energy (partially elastic collision). The results of numerical simulation are consistent with the behaviour of pendulums in real physical models, which makes it possible to simulate an elastic collision between balls when studying their acceleration in auto-balancing devices.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"140 - 154"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49444912","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}

{"title":"Study on Mass and Linear Attenuation Coefficients of PMMA as Human Tissue-Equivalent Material","authors":"M. Hamideen, R. Abady, J. Sharaf","doi":"10.2478/lpts-2022-0012","DOIUrl":"https://doi.org/10.2478/lpts-2022-0012","url":null,"abstract":"Abstract To research the improvements of clinical imaging of human tissues, tissue-equivalent materials are one of the reasonable strategies for evaluating the impact of radiation dosages on human tissues. Hence, considering mass and linear attenuation coefficients is a promising method to foresee the appropriate tissue-identical material. In this examination, we utilise the built-up estimations of elemental compositions (mass portion of every component) of PMMA material by numerous analyses in literature. XCOM program was utilised to figure estimations of mass attenuation coefficients of PMMA for various photon energies (0.015–2.0) MeV. The outcomes reveal that the estimations of mass and linear attenuation coefficients are high as the energies begin to decrease and diminish gradually with an expansion in photon energies. Making a sensible coordinating between mass and linear attenuation coefficients of PMMA as human tissue-equivalent material with mass and linear attenuation coefficients of lung, brain, muscle and blood human tissues has demonstrated a phenomenal match.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"64 - 73"},"PeriodicalIF":0.6,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69229706","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}

{"title":"Study on Potential Role and Benefits of Liquified Natural Gas Import Terminal in Latvia","authors":"A. Ansone, L. Jansons, I. Bode, E. Dzelzītis, L. Zemite, A. Broks","doi":"10.2478/lpts-2022-0010","DOIUrl":"https://doi.org/10.2478/lpts-2022-0010","url":null,"abstract":"Abstract Natural gas is relatively clean energy source, which emits less greenhouse gases (hereinafter – GHG), compared to other fossil fuels, such as hard and brown coal, and therefore it may be the most feasible resource to ensure smooth energy transition towards Europe’s climate neutrality by 2050. Traditional natural gas can be easily transported and used in liquefied (hereinafter – LNG) or compressed form. As for biomethane, in future it also can be used in liquefied (hereinafter – bioLNG) and compressed form, as well as transported by means of the current natural gas infrastructure. It can also significantly enhance regional and national energy security and independence, which has been challenging for the European Union (hereinafter – EU) over at least several decades. Issue on energy independence, security of supply, alternative natural gas sources has been in a hotspot of the Baltic energy policy makers as well. Now, considering Russia’s invasion in Ukraine, since late February 2022, a problem of the EU natural gas dependency on the Russian Federation has escalated again and with force never before experienced. The European natural gas prices also hit records, as the natural gas prices in the Netherlands Title Transfer Facility reached 345 euros per megawatt-hour (hereinafter – EUR/MWh) in March 2022. Therefore, LNG import terminal is the only viable option to reduce national dependency of the so-called pipe gas which in some cases, due to the insufficient interconnections, may be delivered from very limited number of sources. The European policy makers and relevant institutions are currently working towards radical EU natural gas supply diversification, where LNG deliveries coming from outside of Russia will certainly take a central stage. In case of Latvia, the potential benefits of the LNG terminal development in Skulte were evaluated in order to reduce energy independence of the Russian natural gas deliveries in the Baltic region and to introduce new ways and sources of the natural gas flows to the Baltics. LNG terminal in Skulte could ensure significant capital investment cost reduction comparing to other projects proposed for Latvia in different periods, due to already existing natural gas transmission infrastructure and the relative closeness to the Incukalns underground gas storage (hereinafter – UGS). Various aspects, such as technical, political and economic ones, were analysed to assure that Skulte LNG terminal would be a real asset not only to customers of Latvia, but also to those of the whole Baltic region, where in future it would be possible to use biomethane for efficient utilisation of existing and developing natural gas infrastructure.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"37 - 54"},"PeriodicalIF":0.6,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45354113","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}

{"title":"Application Possibilities of the Off-Grid HVAC System Operation Solution for Temporary Shelters in the Latvian Climate Conditions","authors":"D. Zajecs, K. Lebedeva, T. Odiņeca","doi":"10.2478/lpts-2022-0011","DOIUrl":"https://doi.org/10.2478/lpts-2022-0011","url":null,"abstract":"Abstract Temporary shelters are extensively used by emergency services (rescue, disaster relief, military response) and other end-users requiring temporary mobile power solutions for different purposes (event organization, vacation homes, summer camps, etc.). The Covid-19 pandemics resulted in an increase of motor homes worldwide sales. When temporary shelter connection to power grid is impossible, the off-grid liquid fossil fuel generator can be used for electricity generation. Since the liquid fuel supply is often limited, the stock of fuel requires storage that may pose an explosion risk. Quickly installable and energy-efficient ventilation / cooling system with heat recovery is essential to ensure adequate air hygiene and occupants’ comfort in temporary structure. This paper presents a mobile modular electric energy generating unit with photovoltaic (PV) panels for providing temporary shelters (tents) in Latvian climate conditions with heating, ventilation, and air conditioning (HVAC). All calculations were performed using the computer model developed with TRNSYS tool and based on real data from mobile modular energy unit for spring, summer and autumn 2020 and winter 2021. The results show that mobile modular energy unit can be successfully applied for off-grid HVAC system operation of temporary shelters in the Latvian climate conditions.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"55 - 63"},"PeriodicalIF":0.6,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45872195","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}

{"title":"Maximum Shannon Information Delivered in a Lecture","authors":"L. Alksne, A. Ozols","doi":"10.2478/lpts-2022-0008","DOIUrl":"https://doi.org/10.2478/lpts-2022-0008","url":null,"abstract":"Abstract The aim of our paper is to evaluate the maximum Shannon (syntactic) information carried through a video lecture. To achieve the aim, we have considered a natural lecture delivered by a lecturer as a signal transmitted over the physical communication channel consisting of a sound sub-channel and light sub-channel. Receivers are eyes and ears of listeners whose physical characteristics are taken into account. The physiological, neurological and cognitive aspects of the problem are neglected in calculations. The method has been developed to calculate the absolute maximum values of Shannon information characteristics of a natural lecture basing on the capacity formula of continuous communication channel and physical considerations taken into account for the first time, to our knowledge. Maximum Shannon information characteristics (entropies of sound and light frames, amounts of total acoustical and optical information, capacities of sound and light sub-channels, total amount of information and total capacity) of a natural lecture perceived by the audience have been calculated. These values are the upper bounds of a video lecture. The obtained results are discussed in the paper. After some modification, the proposed method can be practically applied for the optimization of both natural and video lectures because there is some correlation between syntactic and semantic information characteristics.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"12 - 22"},"PeriodicalIF":0.6,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48098087","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}