Vilnius Gediminas Technical University
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Renewable Energy in Final Energy Consumption and Income in the EU-28 Countries
No full textThe deployment of renewable energy sources (RES) is considered to be an important objective for the energy sector in the European Union (EU). The EU Directive adapted in 2009 fixed mandatory national targets for the use of renewable energy in transport as well as for the share of RES in the gross final energy consumption. Contrary to previous studies, this paper does not examine the link between the RES and economic growth but rather focuses on real gross domestic product (GDP) and the implementation of national renewable energy targets. We employ panel data models for the case of the EU-28 countries covering the period between 2007 and 2017 that yield a low and positive relationship between the impact of GDP per capita and the share of RES in the final consumption. Our results show that there is a significant causality only from real GDP per capita to the share of renewable energy in final consumption, marking the potential of developed countries to consume more RES. We list some groups of countries according to these variables using a cluster analysis approach. Starting from the proposed panel data models, we constructed the scenarios for the 2020 for various shares of RES and different EU Member States. Overall, it appears that more attention should be attributed to policy proposals in which funding opportunities would be dependent on the achievements of national targets and economic benefits should be given to countries with very good performance in achieving high shares of renewable energy in their final energy consumption.This article belongs to the Special Issue Innovation in Energy Security and Long-Term Energy EfficiencyThe research was partly supported by European Union’s Horizon 2020 project H2020-MSCA-RISE-2014 CLUSDEVMED Grant Agreement Number 645730730
Two-Stage Monitoring of Patients in Intensive Care Unit for Sepsis Prediction Using Non-Overfitted Machine Learning Models
No full textThe presented research faces the problem of early detection of sepsis for patients in the Intensive Care Unit. The PhysioNet/Computing in Cardiology Challenge 2019 facilitated the development of automated, open-source algorithms for the early detection of sepsis from clinical data. A labeled clinical records dataset for training and verification of the algorithms was provided by the challenge organizers. However, a relatively small number of records with sepsis, supported by Sepsis-3 clinical criteria, led to highly unbalanced dataset (only 2% records with sepsis label). A high number of unbalanced data records is a great challenge for machine learning model training and is not suitable for training classical classifiers. To address these issues, a method taking into the account the amount of time the patients spent in the intensive care unit (ICU) was proposed. The proposed method uses two separate ensemble models, one trained on patient records under 56 h in the ICU, and another for patients who stayed longer than 56 h. A solution including feature selection and weighting based training on imbalanced data was proposed in this paper. In addition, several performance metrics were investigated. Results show, that for successful prediction, a particular model having few or more predictors based on the length of stay in the Intensive Care Unit should be applied.This article belongs to the Special Issue Computational Intelligence in Healthcar
Flash Welding of Microcomposite Wires for Pulsed Power Applications
No full textThis paper presents the experimental results of Cu-Nb wire joining upon applying flash welding technology. The present research is aimed at investigating the structure, electrical and mechanical properties of butt welding joints of Cu-Nb conductors, usable for coils of pulsed magnetic systems. The butt joint structure was found to be free of welding defects. The structure of the butt welded joint provides an insignificant increase in electrical resistance and sufficient ultimate strength and plasticity of the joint. The tensile strength of the welded sample reaches 630 MPa
Assessment of Air Pollution with Polychlorinated Dibenzodioxins (PCDDs) and Polychlorinated Dibenzofuranes (PCDFs) in Lithuania
Get PDFPolychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD/F) are highly bioavailable in humans, either through direct inhalation or indirectly by trophic transfer from contaminated food or water. The main sources of pollution with PCDD/F include industrial and non-industrial combustion sources, like domestic contaminated wood burning, house fires, burning of leaves from trees, etc. When looking for alternative energy sources and reduced energy costs, solid waste incineration plants are intended to be built in the vicinity of urbanized areas, and thus, the need emerges for examination and prediction of to what extent the solid waste incineration plants might affect the surrounding ecosystem, air pollution, and human health. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) (or simply PCDD/F congeners) belong to the group of semi-volatile organic compounds with environmental stability and long-range transfer in the ambient air. Dioxin isomers are highly toxic and may have carcinogenic and mutagenic effects in humans. PCDD/F is detected in air, water, sediment, plants and animals. PCDD/F is generally distributed in the particulate phase in ambient air. For solid waste incineration plant emissions, the distribution of PCDD/F particles into particles with a diameter of <10 μm is more than 81% of the total particulate matter, and more than 54% of the PCDD/F is distributed into particles with a diameter of <2.5 μm. The aim of this study is to investigate the sources of PCDD/F, emissions and potential hazards, i.e., a toxic equivalent in Lithuania. The measurements were performed in two largest cities of Lithuania Vilnius and Kaunas, where the level of PCDD/F discovered was from 0.015 to 0.52 pg/m3 and from 0.02 to 0.05 pg/m3, respectively. The sites for the monitoring were selected based on their proximity to the locations of the planned cogeneration power plants in these cities.This article belongs to the Section Air Quality and Human Healt
Application of Hybrid SWARA–BIM in Reducing Reworks of Building Construction Projects from the Perspective of Time
No full textOne of the major issues of the construction industry has been the “reworks” that affect the time, quality, and cost of projects. Therefore, reworks and the ineffective use of site resources and materials will always result in significant losses on projects. The development of information technology has led to the widespread use of Building Information Modelling (BIM) to enhance the delivery of more sustainable building construction projects. The purpose of this study is to combine the Step-wise Weight Assessment Ratio Analysis (SWARA) method and BIM technologies to identify and reduce time delays caused by reworks in construction projects. Firstly, 49 rework causes in residential buildings were identified and ranked. Then, BIM was generated and compared to the initial model. It was observed that working hours were reduced by 4.6%. Moreover, using an Earned Value Management (EVM) system, a 0.06 increase in Schedule Performance Index (SPI) factor was illustrated. Results obtained by this study provide an effective step in reducing a project’s time in the construction industry.This article belongs to the Special Issue Sustainable Construction Engineering and Managemen
The Effect of Different Plant Oil Impregnation and Hardening Temperatures on Physical-Mechanical Properties of Modified Biocomposite Boards Made of Hemp Shives and Corn Starch
No full textIn this study, tung tree and linseed drying oils, as well as semi-drying hempseed oil, were analyzed as the protective coatings for biocomposite boards (BcB) made of hemp shives, corn starch binder, and the performance-enhancing additives. The hydrophobization coatings were formed at 40, 90, and 120 °C temperatures, respectively. The physical-mechanical properties such as the compressive strength, thermal conductivity, dimensional stability, water absorption, and swelling were tested. In addition, scanning electron microscopy (SEM) was employed for the analysis of the board microstructure to visualize the oil fills and impregnation in pores and voids. It was demonstrated that the compressive strength of oil-modified BcBs compared to uncoated BcBs (at 10% of relative deformation) increased by up to 4.5-fold and could reach up to 14 MPa, water absorption decreased up to 4-fold (from 1.34 to 0.37 kg/m2), swelling decreased up to 48% (from 8.20% to 4.26%), whereas the thermal conductivity remained unchanged with the thermal conductivity coefficient of around 0.085 W/m·K. Significant performance-enhancing properties were obtained due to the formation of a protective oil film when the tung tree oil was used.This article belongs to the Section Advanced CompositesThis research was funded by the Research Council of Lithuania (LMT) grant S-MIP-19-61. The APC was funded by the Research Council of Lithuania (LMT) grant S-MIP-19-61
Improving Fuel Economy of Spark Ignition Engines Applying the Combined Method of Power Regulation
No full textOne of the disadvantages of spark ignition engines, whose power is regulated by throttling, is the increased fuel consumption at low loads and when the engine is idle. The combined method of engine power regulation by switching off the cylinder group and throttling working cylinders is one of the effective ways to improve fuel economy in the above-mentioned modes. This article presents the research results of the combined method of engine power regulation which can be realized by minor structural changes in operating conditions. The method implies the following: at low loads and at idle speed of the engine. Fuel supply to the group of cylinders is switched off with the simultaneous increase of the cyclic fuel supply in the working cylinders. The adequacy of the calculated results has been checked by the indication of operating processes in switched off and working cylinders. The research results of a six-cylinder spark ignition engine with the distributed gasoline injection using the combined power regulation system have been shown. The angles of opening the throttle which provides a non-shock transition from the operation with all cylinders to the operation with the cylinder group switched off have been determined.This article belongs to the Special Issue Advances in Spark-Ignition Engine
A Novel Integrated PIPRECIA–Interval-Valued Triangular Fuzzy ARAS Model: E-Learning Course Selection
No full textThe development of information and communication technologies has revolutionized and changed the way we do business in various areas. The field of education did not remain immune to the mentioned changes; there was a gradual integration of the educational process and the mentioned technologies. As a result, platforms for distance learning, as well as the organization of e-learning courses of various types, have been developed. The rapid development of e-learning courses has led to the problem of e-learning course selection and evaluation. The problem of the e-learning course selection can be successfully solved by using multiple-criteria decision-making (MCDM) methods. Therefore, the aim of the paper is to propose an integrated approach based on the MCDM methods and symmetry principles for e-learning course selection. The pivot pairwise relative criteria importance assessment (PIPRECIA) method is used for determining the weights of criteria, and the interval-valued triangular fuzzy additive ratio assessment (ARAS) method is used for the ranking of alternatives i.e., e-learning courses. The suitability of the proposed integrated model is demonstrated through a numerical case study.This article belongs to the Special Issue Symmetric and Asymmetric Data in Solution ModelsThe APC was funded by: Department of Project Management, Ho Chi Minh City Open University, Ho Chi Minh City, Vietnam; and Faculty of Applied Management, Economics and Finance, University Business Academy in Novi Sad, Belgrade, Serbia
An Assessment of Provision of Heterogeneous Services for Sustainable Cargo Transportation Process Management by Roads
No full textThe aim of this research is forwarded for assessment of provision possibilities of the multi-componential and heterogeneous services in the fast-changing topology of cargo transportation processes. The mobile intelligent services in current transport means require the development of complex infrastructure for multi-compositional service support. Our objectives are related to the investigation in data-transfer capabilities for heterogeneous service support, which is offering some improvements for developing the infrastructure of transportation of vehicles and helping in the administration of transport processes. This research aims to develop an approach for the assessment of infrastructure for sustainable management of cargo transportation processes by roads. Such assessment is multi-layered by including the management possibilities of cargo transportation logistic processes and electronic (smart, mobile) services using current innovative software and hardware of information communication technologies (ICT). Special attention is paid for road safety, more environment cleanable, and paperless management by assessing the integration of potentials and prospects of wireless, vehicle ad-hoc communication networks (VANET), and other communication possibilities. Some requirements are revealed for such type of infrastructure for the provision of heterogeneous services. The results of the development of infrastructure demonstrate the capacities of the potential of wireless networks for the provision of high-level of multi-component, heterogeneous services.This article belongs to the Section Sustainable TransportationThis research was funded by Research Council of Lithuania (LMTLT) grant number 01.2.2-LMT-K-718-03-0030
Investigation and evaluation of 137Cs and 90Sr migration from soil to conifer trees
No full textDisertacijoje nagrinėjama dirbtinės kilmės radionuklidų (137Cs ir 90Sr) pernaša iš dirvožemio į medį. Pagrindinis šio darbo uždavinys – nustatyti 137Cs ir 90Sr savituosius aktyvumus tyrimui parinktuose medžiuose bei įvertinti šių radionuklidų pasiskirstymo juose ypatumus, pasiūlyti metodiką radionuklido pernašos iš dirvožemio į medį vertinimui pagal radionuklido cheminį analogą dirvožemyje po medžio laja, atlikti radionuklido pernašos iš dirvožemio į medį prognozę, parinkus tinkamiausius modelius.
Šiame darbe sprendžiami tokie pagrindiniai uždaviniai: atlikti medžių sandų radiometrinius, radiocheminius ir pušų biologinio pažeistumo tyrimus; įvertinti tiriamųjų radionuklidų ir jų stabiliųjų cheminių analogų savituosius aktyvumus bandiniuose; įvertinti 137Cs ir 90Sr pernašos iš dirvožemio į medžius ir pasiskirstymo juose ypatumus, atsižvelgiant į dirvožemio radioaktyviąją užtaršą ir augalo vystymosi ypatumus; modeliuoti 137Cs ir 90Sr migracijos sistemoje „dirvožemis–medis“ sklaidą, įvertinti radionuklidų sukauptą augale kiekį, modeliuoti augalo patiriamą vidinę apšvitą.
Disertaciją sudaro įvadas, penki skyriai, bendrosios išvados, rekomendacijos, naudotos literatūros ir autorės publikacijų sąrašai.
Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Pristatomos disertacijos tema autorės paskelbtos publikacijos, pranešimai, disertacijos struktūra.
Pirmasis skyrius skirtas mokslinės literatūros apžvalgai, kurioje analizuojama dirbtinės kilmės radionuklidų (137Cs ir 90Sr) pernaša sistemoje „dirvožemis–medis“ ir ją lemiantys veiksniai.
Antrajame skyriuje pateiktos dirbtinės kilmės radionuklidų (137Cs ir 90Sr) ir jų cheminių analogų (40K ir Ca) tyrimo, modeliavimo metodikos.
Trečiajame skyriuje pateikti 137Cs ir 90Sr ir jų cheminių analogų (40K ir Ca) tyrimo rezultatai, atlikta rezultatų analizė.
Ketvirtajame skyriuje pateikiami radionuklidų sklaidos sistemoje „dirvožemis–medis“ modeliavimo rezultatai, įvertinant galimą vidinę medžio apšvitą.
Penktajame skyriuje pateikiama sukurta metodika, skirta įvertinti 137Cs pernašą iš dirvožemio į medį, pagal cheminio analogo savitąjį aktyvumą dirvožemyje. Pagal ją pateikta patentinė paraiška.
Disertacijos tema yra atspausdinta 15 mokslinių straipsnių, perskaityta 10 pranešimų konferencijose Lietuvoje ir kitose šalyse.Daktaro disertacij