Latvian Journal of Physics and Technical Sciences最新文献_第8页

Axial Flux Switching Permanent Magnet Alternator with External Magnetic Cores 外磁芯轴向磁通开关永磁交流发电机

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0025

V. Bezrukovs, V. Bezrukovs, M. Konuhova, D. Bezrukovs, A. Berzins

引用次数: 1

Radar Observations of Old Centaur Rocket from 1966 1966年对旧半人马座火箭的雷达观测

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0021

Y. Bondarenko, D. Marshalov

引用次数: 0

Artificial Intelligence Meets Radio Astronomy 人工智能与射电天文学相遇

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0027

G. Tuccari, G. Tuccari

引用次数: 0

Multifocal Near-Eye Display: Timing of Optical Diffuser Elements and Synchronization to DLP-Based Projection Microunit 多焦近眼显示:光学扩散元件的定时和基于dlp的投影微处理器的同步

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0013

R. Ruskuls, K. Slics, R. Ozoliņš, R. Fenuks, E. Linina, K. Osmanis, I. Osmanis

{"title":"Multifocal Near-Eye Display: Timing of Optical Diffuser Elements and Synchronization to DLP-Based Projection Microunit","authors":"R. Ruskuls, K. Slics, R. Ozoliņš, R. Fenuks, E. Linina, K. Osmanis, I. Osmanis","doi":"10.2478/lpts-2022-0013","DOIUrl":"https://doi.org/10.2478/lpts-2022-0013","url":null,"abstract":"Abstract The paper present the key technical details of a multifocal near-eye display concept. Along with an overview of the basic architecture, a particular implementation that utilises a digital light processing (DLP®) based spatial light modulator as the image source is provided in the study. The investigated approach involves the utilisation of a small-scale volumetric screen formed by a stack of fast-switching optical diffuser elements based on liquid crystal technology. The volumetric screen is illuminated by a rear image projector. To make the whole system functional and small, the challenge lies within the development of integrated control board for the projection modules as well as the synchronization of the DLP® projector image output to the optical diffuser element switching-cycle. The main difficulty of the development process is accounting for the peculiarities of in-house developed diffuser elements and the off-the-shelf DLP®, which is the main focus of this paper. There is no direct control over the full set of DLP® operational parameters, an indirect method for adjusting frame dead time is proposed, showing that an increase in dead time close to 0.3 ms (from 0.3 ms to 0.6 ms in the particular setup) can be achieved without significantly sacrificing image colour depth or quality. Tuneable dead time mitigates the limitations set by the non-instantaneous switching of liquid crystal diffuser elements as longer dead times allow for the removal of image bleeding between frames.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"106 - 115"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43935563","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

Importance of Spectrum Management in Radio Astronomy 频谱管理在射电天文学中的重要性

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0022

J. Kallunki, V. Bezrukovs, W. Madkour, P. Kirves

引用次数: 1

Specifics of Power Losses in Power Lines Including Parallel Lines 电力线(包括平行线)的功率损耗细节

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0017

J. Survilo

{"title":"Specifics of Power Losses in Power Lines Including Parallel Lines","authors":"J. Survilo","doi":"10.2478/lpts-2022-0017","DOIUrl":"https://doi.org/10.2478/lpts-2022-0017","url":null,"abstract":"Abstract Reducing power losses is invested in the trend of combating climate warming. It is necessary to know what parameters of power transmission lines affect the losses in them. In short and medium lines with accounted lumped parameters, the role and influence of the line parameters on losses are visible. In the lines with distributed parameters, at least with one series parameter and one parallel parameter, the role played by them, computing losses in ordinary way as difference between power at line sending and receiving end, is hidden. This is pronounced when considering parallel lines. In two parallel lines the losses can be greater than in a single line. This may occur when the current at the end of the lines is less than the boundary value: the value when two parallel lines and a single line have the same losses. The longer the line and the higher the rated voltage, the stronger the effect. In view of this aspect, it is necessary to know the boundary current. This current can be determined in ordinary way by a series of calculations changing the load value. In some cases, boundary current is affected not only by modulus of the current at the end of the line but also by its angle. It is better to calculate the boundary current by a formula, while studying the role of each parameter.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"155 - 169"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43496542","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

Magnetic Flux Switching Type Permanent Magnet Generator for Bicycles: Modelling and an Experimental Study 磁通开关式自行车永磁发电机的建模与实验研究

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0024

V. Bezrukovs, V. Bezrukovs, M. Konuhova, D. Bezrukovs, A. Berzins, J. Trokšs

引用次数: 1

Microwave Observations of the Sun with Virac RT-32 Radio Telescope: The Expansion of Possibilities Virac RT-32射电望远镜对太阳的微波观测：可能性的扩大

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0019

D. Bezrukovs

{"title":"Microwave Observations of the Sun with Virac RT-32 Radio Telescope: The Expansion of Possibilities","authors":"D. Bezrukovs","doi":"10.2478/lpts-2022-0019","DOIUrl":"https://doi.org/10.2478/lpts-2022-0019","url":null,"abstract":"Abstract Nowadays there is increasing interest in narrowing coronal areas with reduced brightness temperatures (LTR – Low Temperature Regions) associated with local open magnetic fields (S-web, “coronal partings”, “dark coronal corridors”) as one of the eventual sources of slow solar wind. Ventspils International Radio Astronomy Centre (VIRAC) performs routine spectral polarimetric observations of the Sun with RT-32 radio telescope equipped with the multi-channel (16 frequency channels) spectral polarimeter for the wave length range of 3.2–4.7 cm (6.3–9.3 GHz) and both circular polarizations simultaneously. The analysis of relevant tasks of clear and reliable observations and detections of LTR shows the necessity to improve noise parameters, dynamic range and stability of the actual solar spectral polarimeter and to expand its wavelength range. Taking into account these requirements, the low noise and thermally stabilized solar spectral polarimeter was developed. The new multi-channel spectral polarimeter is expected to observe right and left circular polarization of the solar emission in the wavelength range of 2.1–7.5 cm (4.1–14.3 GHz) divided into 12 frequency bands. The dynamic range was expanded to >36 db and the signal/noise ratio (referred to as quiet Sun brightness temperatures) was enhanced to > 22–24 db. The paper deals with some test observations of the newly developed solar spectral polar-imeter and its feature analysis. Some eventual problems of solar physics which could be solved with the spectral polarimeter are also discussed.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"5 - 13"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43859345","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

Observations of Weak Galactic OH Masers in 1.6 GHz Frequency Band Using Irbene RT-32 Radio Telescope Irbene RT-32射电望远镜对1.6 GHz频段弱星系OH脉泽的观测

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0020

K. Šķirmante, V. Bezrukovs, M. Bleiders, G. Jasmonts, N. Jekabsons, M. Nechaeva

引用次数: 1

Scenario-Based Modelling of Residential Sector Consumption: A Case Study in Latvia 基于情景的住宅部门消费建模——以拉脱维亚为例

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Latvian Journal of Physics and Technical Sciences Pub Date : 2022-06-01 DOI: 10.2478/lpts-2022-0014

E. Kairisa, A. Mutule, I. Drovtar, T. Korõtko, O. Borščevskis, H. Wilkening, Ch. Troyer

{"title":"Scenario-Based Modelling of Residential Sector Consumption: A Case Study in Latvia","authors":"E. Kairisa, A. Mutule, I. Drovtar, T. Korõtko, O. Borščevskis, H. Wilkening, Ch. Troyer","doi":"10.2478/lpts-2022-0014","DOIUrl":"https://doi.org/10.2478/lpts-2022-0014","url":null,"abstract":"Abstract Promoting the development of energy communities is one of the planned development areas mentioned in the Latvian National Energy and Climate Plan (NECP). Even though energy communities do not yet exist in Latvia, they could improve the quality of the environment and stimulate the local economy. In any case, it is expected that the structure of household energy consumption in Latvia will change as households start to adopt new technologies such as electric cars and heat pumps, as well as participate in energy production and demand response. Often the starting point for the development of an energy community is the geographic location of consumers. Therefore, for this study, a microdistrict was chosen in one of the most developed suburbs of Riga in Latvia, in which 76 households are located. The study identified five milestones on the path from mere neighborhood to the energy community. The resLoadSIM Residential Load Simulation tool was chosen to simulate realistic energy consumption with a 1-minute time resolution, as well as to model the future solar energy consumption and generation in the community on its way to becoming an energy community and meeting these goals. The network constraints associated with the transformer and lines are taken into account and it is assumed that the district will not invest in the development and expansion of the network. Based on the results of the modelling, an analysis was made of the impact of the development of the energy community in Latvia and how each stage of development will affect energy consumption, the amount of renewable energy, the energy sent to the grid, the power consumed directly, and the share of solar energy in energy consumption.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"59 1","pages":"116 - 127"},"PeriodicalIF":0.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48929844","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: 1