Latvian Journal of Physics and Technical Sciences最新文献

Applying Dynamic U-Value Measurements for State Forecasting in Buildings 应用动态 U 值测量进行建筑状态预测

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0047

J. Telicko, A. Jakovics

{"title":"Applying Dynamic U-Value Measurements for State Forecasting in Buildings","authors":"J. Telicko, A. Jakovics","doi":"10.2478/lpts-2023-0047","DOIUrl":"https://doi.org/10.2478/lpts-2023-0047","url":null,"abstract":"Abstract In the present day, monitoring and automated control stand as pivotal factors for the energy-efficient and comfortable operation of buildings. As the demand for indoor climate control grows, building management systems have become more intricate, making their control challenging due to the increasing number of controllable elements. Replacing manual human analysis of complex systems can be achieved through the utilization of algorithms like model-based control. It is important to note that performance of this method usually relies on the accuracy of neural network-based building state forecasts. Studying the internal dynamics of climate as influenced by temperature changes necessitates a brief record of measurements, whereas evaluating structural modifications through moisture transfer demands data covering a more extended period. Neural networks such as Long Short-Term Memory have the potential to lose information within lengthy time-series data, and the intricate nature of moisture transfer further adds complexity to the task of approximating functions, ultimately leading to a reduction in energy efficiency. In order to improve the precision of indoor climate predictions, our suggestion involves not only assessing changes in temperature but also considering alterations in U-values triggered by temperature variations and moisture transfer. Our preliminary assessment of the influence of U-value, conducted through numerical simulations using WUFI6, exposes variations of up to 10 % of U-value in certain scenarios. Dealing with these computations in real time using physical models proves to be demanding due to computational requirements and limited data availability. To tackle this issue, we present an innovative preprocessing approach for on-the-fly evaluation of U-values. Empirical trials involving three years of monitoring data indicate that the suggested technique led to an approximate 8 % reduction in the average mean squared error of climate predictions based on neural network models, in specific instances.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":" 9","pages":"81 - 94"},"PeriodicalIF":0.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138615266","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

Density-Based Topological Optimization of 3D-Printed Casts for Fracture Treatment with Freefem Software 利用 Freefem 软件对用于断裂处理的三维打印铸件进行基于密度的拓扑优化

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0050

K. Kokars, A. Krauze, K. Muiznieks, J. Virbulis, P. Verners, A. Gutcaits, J. Olins

{"title":"Density-Based Topological Optimization of 3D-Printed Casts for Fracture Treatment with Freefem Software","authors":"K. Kokars, A. Krauze, K. Muiznieks, J. Virbulis, P. Verners, A. Gutcaits, J. Olins","doi":"10.2478/lpts-2023-0050","DOIUrl":"https://doi.org/10.2478/lpts-2023-0050","url":null,"abstract":"Abstract 3D printed plastic casts can be used for healing bone fractures. The main requirements for these cases are: they should be light, require little printing time, have good mechanical properties, and ensure proper skin ventilation. We present a density-based topology optimization algorithm for obtaining optimal cast shapes that fulfil these requirements. The algorithm uses a linear stress model and simplified boundary conditions to model the contact problems. The cast shapes were optimized against the influence of several sharp corners. The parametric studies showed that the mass of optimized casts was reduced by 20 %–25 % in comparison with original industrial casts, and the printing time is reduced by 1.4–1.7 h for the largest cast. A major model drawback is the use of 3D numerical volume to model the density distribution. The density distribution should be homogenized across the cast layer. The overhang problem should also be addressed. We also suggest that the cast producers collect more experimental data on the cast breakages for a better calibration of the numerical model.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":" 12","pages":"124 - 141"},"PeriodicalIF":0.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138617189","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

Building Ventilation Optimization Through Occupant-Centered Computer Vision Analysis 通过以住户为中心的计算机视觉分析优化楼宇通风

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0045

J. Telicko, K. Bolotin

{"title":"Building Ventilation Optimization Through Occupant-Centered Computer Vision Analysis","authors":"J. Telicko, K. Bolotin","doi":"10.2478/lpts-2023-0045","DOIUrl":"https://doi.org/10.2478/lpts-2023-0045","url":null,"abstract":"Abstract Buildings consume about 40 % of all energy. Ventilation plays a significant role in both the energy consumption of buildings and the comfort of occupants. To achieve energy efficiency and comfort, smarter ventilation control algorithms can be employed, such as those with feedback based on CO2 levels. Furthermore, by knowing the current number of people in a space, ventilation can theoretically be adjusted to maintain a constant CO2 level without wasting energy when people are not present. An additional benefit of such control could arise due to occupants’ habits. For example, if a person senses elevated CO2 levels, even if the ventilation system has started operating more intense, they might choose to open a window, potentially compromising energy efficiency. Therefore, if the control algorithm were to maintain a constant CO2 level, occupants may be less likely to open windows. In our work, we explore a model in combination with a custom monitoring system based on computer vision to implement such control. The monitoring system combines outside and inside CO2 sensors with precise people counting based on computer vision to provide data to the model. The model relies on the mass balance equation for CO2 and considers the historical data of the number of occupants and their activities to estimate the overall CO2 generation in indoor spaces. The results suggest that the model can effectively forecast CO2 dynamics with an absolute deviation of 40 ppm. However, it was observed that the analysis of the actual air exchange level could be compromised by several factors.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":" 18","pages":"60 - 70"},"PeriodicalIF":0.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138620349","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

Influence of Surface Waves on Liquid-to-Gas Mass Transfer in Molten Silicon 表面波对熔融硅中液气传质的影响

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0049

G. Zageris, V. Geža, S. Pavlovs

{"title":"Influence of Surface Waves on Liquid-to-Gas Mass Transfer in Molten Silicon","authors":"G. Zageris, V. Geža, S. Pavlovs","doi":"10.2478/lpts-2023-0049","DOIUrl":"https://doi.org/10.2478/lpts-2023-0049","url":null,"abstract":"Abstract The paper focuses on the numerical analysis of the mass transfer of impurities from the wavy surface of molten silicon to the gas phase. The mathematical model is described herein, with the modelling of a wavy silicon melt surface being done with the moving mesh technique. The model employs assumptions about the mass transfer process on the surface, namely, that it can be modelled with effective diffusion across the interface. The assumption is verified against limited experimental data for a stationary melt surface, and reasonable agreement is obtained. Thereafter, numerical studies are undertaken for a wavy melt surface. The dependence of impurity removal rate on the wave amplitude, wavelength and frequency is analysed. It is shown that the waves on the surface of the liquid increase the mass transfer rate in a certain parameter range. Finally, results are analysed to find an explanation for this increase and to determine technological factors that impact it. Surface enlargement due to waves and altered flow patterns near the silicon melt are determined as potential reasons for the improved impurity removal rate. A dimensionless criterion for the minimal wave amplitude required to obtain improved impurity removal is found and discussed.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":" 11","pages":"106 - 123"},"PeriodicalIF":0.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138618057","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

Modelling of Methanol Production From Biogas 利用沼气生产甲醇的模型制作

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0043

V. Kharitonov, V. Geža, L. Rodin, M. Shorohov

引用次数: 0

Porous Material for Gas Thermal Compression in Space Conditions: Thermal Design Aspects 用于空间条件下气体热压缩的多孔材料：热设计方面

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0048

I. Ušakovs

引用次数: 0

CFD Analysis of Airborne Pathogen Disinfection in a UV-C Air Purification Device 紫外线-C 空气净化装置中空气传播病原体消毒的 CFD 分析

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0042

A. Sabanskis, D. D. Vidulejs, J. Virbulis, A. Jakovics

引用次数: 0

Numerical Insights Into Gas Mixing System Design for Energy Conversion Processes 能源转换过程中气体混合系统设计的数值见解

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0044

M. Klevs, G. Zageris, A. A. Ziemelis, V. Dzelme, V. Geža, A. Jakovics

引用次数: 0

Numerical Model and System for Prediction and Reduction of Indoor Infection Risk 预测和降低室内感染风险的数值模型和系统

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0041

J. Virbulis, J. Telicko, A. Sabanskis, D. D. Vidulejs, A. Jakovics

引用次数: 0

The Use of Renewable Energy and Capillary Heat Exchangers for Energy Savings in the Existing Apartment 利用可再生能源和毛细管换热器为现有公寓节约能源

IF 0.6

Latvian Journal of Physics and Technical Sciences Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0046

S. Gendelis, A. Jakovics, O. Pulkis, I. Bukans

{"title":"The Use of Renewable Energy and Capillary Heat Exchangers for Energy Savings in the Existing Apartment","authors":"S. Gendelis, A. Jakovics, O. Pulkis, I. Bukans","doi":"10.2478/lpts-2023-0046","DOIUrl":"https://doi.org/10.2478/lpts-2023-0046","url":null,"abstract":"Abstract The use of capillary heat exchangers with a large area means the lowest heat carrier temperature – typically less than 30 °C for heating. This determines the very efficient use of the installed heat pump due to an increase in the coefficient of performance (COP) with a decrease in the provided water temperature. The aim of the study was to find out whether renewable energy sources and radiant capillary heat exchangers increase energy efficiency. In order to achieve the maximum energy efficiency during the renovation of the existing apartment, a combination of two green approaches was used. One of them is the replacement of the existing high-temperature radiator heating system with radiant capillary mats. The same system is also used for cooling, which was not possible with the existing system. The necessary energy is provided from renewable aerothermal energy by installing a heat pump together with PV panels to ensure electricity consumption. The measurements were made in the apartment to determine the thermal transmission properties of all boundary structures and an air exchange rate using long-term monitoring. Experimental data were used to create the heat balance, to estimate the heating and cooling powers, as well as the seasonal energy needs. The amount of capillary heat exchangers and the size of the heat pump were chosen accordingly. The very first energy consumption data allow concluding that the planned improvement of the energy efficiency has been successfully achieved by using technology combination described without improvement of the thermal properties.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":" 7","pages":"71 - 80"},"PeriodicalIF":0.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138611588","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