Vilnius Gediminas Technical University
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Kalibravimo sistemos dinaminiai tyrimai
No full textModerniuose įrenginiuose kalibravimas yra realizuojamas dinaminiu režimu, kai matuojamo objekto rastrinių elementų padėtis detektuojama judant paslankiems matavimo įrenginio junginiams. Šio proceso metu veikia išoriniai ir vidiniai virpesių šaltiniai. Šiame darbe tyrimo objektas yra naujai sukurtas kampo matavimo komparatorius, dirbantis dinaminiu režimu. Pagrindinis tyrimo tikslas yra nustatyti kampo komparatoriaus dinamines charakteristikas bei palyginti eksperimentinius ir teorinius skaičiavimus
Rastrų formavimo įrenginio dinaminiai tyrimai
No full textModerniuose įrenginiuose darbiniai procesai atliekami dinaminiu režimu. Formuojant rastrus dinaminiu režimu įrenginio konstrukciją veikia išoriniai ir vidiniai virpesių šaltiniai. Šiame darbe tyrimo objektas yra rastrų formavimo įrenginis, dirbantis dinaminiu režimu. Pagrindinis tyrimo tikslas yra nustatyti rastrų formavimo įrenginio juostos poslinkio matavimo sistemos mazgo charakteristikas
Modified asphalt mixtures for heavy duty pavement wearing layers
No full textAsphalt pavements perform in a wide range of temperatures, especially in Eastern European countries, where the daily mean temperature of asphalt layers varies from −18 °C during winter to 47 °C during summer or even higher under more severe climatic conditions. Low temperatures preclude the use of high-stiffness binders because of their high susceptibility to thermal cracking. High temperatures during summer and a heavy static load contribution cause rutting, slippage, and high plastic deformation of heavy duty asphalt pavements. Many research programs on asphalt wearing layers affected by long-lasting high stress have been initiated to address this problem. Our theoretical analysis led to a plan and subsequent detailed laboratory research of modified AC 11 VS and SMA 11 S asphalt mixtures. We analyzed 11 different bitumens and the modification of the asphalt mixture aggregate distribution. The experimental results show extremely good rutting performance of the modified asphalt mixtures.This work was supported by the European Social Fund [Grant
number VP1-3.1-ŠMM-10-V-02-022]
Influence of Calcite Particles on Mechanical Properties of Grouted Sandy Soil
Get PDFChemical and mineralogical content of sands has very high influence on uniaxial compressed strength of grouted soils. In this paper
influence of calcite particles in sand on mechanical properties of grouted with urea-formaldehyde resin sandy soil is described.
Long-lasting experimental laboratory investigations are executed. In result of our investigations we make conclusion, that addition
of calcite particles in sandy soil decreased compressed strength of grouted soil specimens observed in time of 3 months.12th international conference “Modern Building Materials, Structures and Techniques” (MBMST 2016
Component Method in the Strength Evaluation of Cold-formed Steel Joints
Get PDFNowadays, there is a growing tendency in the use of cold formed constructions, which may be explained by good strength to cost ratio. Thus, the goal of this paper is to investigate the strength of cold-formed steel beam-to-column bolted gusset-plate joints. In the paper the model of moment resistance of such joints based on the component method is presented. The calculation of resistance of steel components is based on EN 1993-1-8 and EN 1993-1-1. Two types of gusset plates are investigated: I-shape and T-shape. The developed model is well in line with the full-scale experimental results.12th international conference “Modern Building Materials, Structures and Techniques” (MBMST 2016
Influence of technological and environmental factors on the behaviour of the reinforcement anchorage zone of prestressed concrete sleepers
No full textThe article analyses the influence of technological factors on variations in the stress and strain state during the production of prestressed concrete sleepers. The paper focuses on technological damage to the anchorage zone and its influence on concrete and the pretensioned reinforcement of the last prestressed concrete sleepers located by abutments. The article presents the calculation principles of stresses caused by thermal and humidity deformations, compares theoretical and experimental results and specifies the nature of damages. The paper deals with concrete structure and an interface between reinforcement and concrete of new and three years old prestressed concrete sleepers, explores the results of laboratory tests on deteriorating the ends of new prestressed concrete sleepers under freezing and thawing cycles, looks at changes in concrete structure and the interface between reinforcement and concrete at the ends and in the middle of prestressed concrete sleepers applying a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). Secondary ettringite formation (DEF) in concrete micro-cracks and at the interface between reinforcement and concrete and elemental composition of the formed crystals have been determined. Significant difference in concrete structure and new solid phases at the ends of used and new sleepers has been defined. Concrete structure in the middle of the three years old railway sleeper has remained almost unchanged. The obtained results show that technological factors are affecting the deterioration nature of the ends of prestressed concrete sleepers.Authors are grateful to Civil Engineering Scientific Research
Centre of Vilnius Gediminas Technical University and Laboratory
of Building Products Technology in the Scientific Institute of Thermal Insulation, Vilnius Gediminas Technical University for equipment and infrastructure, which were employed for investigatio
Higher education and neoliberal temptation : a conversation with Henry Girou
No full textSamalavičius, A. L.; Giroux, H. 2016. Higher education and neoliberal temptation : a conversation with Henry Girou, Elektroninis išteklius. Eurozine. [www.eurozine.com] : the netmagazine. Vienna : Eurozine, 2016. ISSN 1684-4637. p. [1-7
Personnel ranking and selection problem solution by application of KEMIRA method
No full textIn this study KEmeny Median Indicator Rank Accordance (KEMIRA) method is applied for solving personnel ranking and selection problem when there are two subgroups of evaluating criteria. Each stage of KEMIRA method illustrated with the examples. In the first stage Kemeny median method is applied to generalize experts’ opinions for setting criteria priorities. Medians were calculated for all experts opinions generalization and for experts majority opinions generalization. In the second stage criteria weights calculated and alternatives ranking accomplished simultaneously by Indicator Rank Accordance method. The obtained solutions compared with the results received in previous work of authors
Evaluation of Combined Heat and Power (CHP) Systems Using Fuzzy Shannon Entropy and Fuzzy TOPSIS
No full textCombined heat and power (CHP) or cogeneration can play a strategic role in addressing environmental issues and climate change. CHP systems require less fuel than separate heat and power systems in order to produce the same amount of energy saving primary energy, improving the security of the supply. Because less fuel is combusted, greenhouse gas emissions and other air pollutants are reduced. If we are to consider the CHP system as “sustainable”, we must include in its assessment not only energetic performance but also environmental and economic aspects, presenting a multicriteria issue. The purpose of the paper is to apply a fuzzy multicriteria methodology to the assessment of five CHP commercial technologies. Specifically, the combination of the fuzzy Shannon’s entropy and the fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) approach will be tested for this purpose. Shannon’s entropy concept, using interval data such as the α-cut, is a particularly suitable technique for assigning weights to criteria — it does not require a decision-making (DM) to assign a weight to the criteria. To rank the proposed alternatives, a fuzzy TOPSIS method has been applied. It is based on the principle that the chosen alternative should be as close as possible to the positive ideal solution and be as far as possible from the negative ideal solution. The proposed approach provides a useful technical–scientific decision-making tool that can effectively support, in a consistent and transparent way, the assessment of various CHP technologies from a sustainable point of view
An index to measure sustainability of a business project in the construction industry: Lithuanian case
No full textThe continuous growth of the world population, resource scarcity and the threat of climate change pose numerous environmental and social problems to the world. Therefore, much hope is put in the concept of sustainability. Companies are increasingly coming under strong global pressure to incorporate sustainability considerations into their project decision-making process. Business projects in the construction industry are among the most important, as this sector is one of the largest sectors and of major importance for the national economy and therefore has a huge impact on the environment and society. Thus, we have to explore ways to integrate sustainability into the management of those projects. This paper presents a composite sustainability index of a project (CSIP) which has been created following a review of existing literature and a pilot research study. A pilot research study was conducted in the Lithuanian construction industry between January 2015 and June 2015. Sustainability criteria were chosen and grouped on the basis of the analysis of the literature and different standards relating to sustainability applicable in the construction industry. A survey was used to select and rank the most important sustainability criteria. The index was constructed using multi-criteria decision-making methods. The results of the pilot study revealed that practitioners in the Lithuanian construction sector attach most importance to 15 sustainability criteria. A composite sustainability index of a project combining all these criteria may be useful in assessing the sustainability of a business project and making decisions regarding project portfolio selection and financial resource allocation. When addressing the issue of financial resource allocation in a project portfolio, the decision-maker could take into account not only the project’s return and risk, but also its sustainability. The understanding of this study should