Vilnius Gediminas Technical University
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Deformations of FRP–Concrete Composite Beam: Experiment and Numerical Analysis
No full textAdvanced materials have been created for structural application during the past decades. Engineers, however, faced severe problems due to the absence of a reliable technique for ensuring the required structural properties minimising the amount of material used. A lack of constitutive models for the analysis of the structural systems also exists. Residual stiffness of flexural concrete elements subjected to short-term load is the focus of this research. Tension-stiffening models were developed to represent the deformation response of the members reinforced with internal bars. This study examines the suitability of the tension-stiffening modelling approach for simulating the deformation behaviour of the composite specimens comprising glass fibre-reinforced polymer (GFRP) pultruded profile adhesively bonded to the tensile surface of the concrete beam. The study employs a nonlinear finite element approach and analytical model to simulate the deformation behaviour of the flexural elements.This article belongs to the Section Civil EngineeringThe European Social Fund funded this research and APC within the framework of the project “Development of Competences of Scientists, other Researchers and Students through Practical Research Activities” (Project No 09.3.3-LMT-K-712)
Microwave Analysis of Scattered and Absorbed Powers of Semiconductor and Metamaterial Cylinder Structures
No full textHere is presented our numerical investigations based on the rigorous solution of the Maxwell’s equations for analyses of absorbed and scattered powers of a semiconductor-metamaterial array with a window defect. The array structure consists of a finite set of infinite parallel, circular cylinders that can be made of the different lossy and/or lossless isotropic materials. We used our developed computer code, which allowed us to consider an array consisting of an arbitrary number of cylinders. According to our code, cylinders can be located at different distances and have differing diameters. There is a limitation: Cylinders should not cross each other. We numerically examined two cylindrical arrays with electromagnetic (EM) band-gap (EBG) defects. The absorbed and scattered powers were analyzed there for parallel and perpendicular polarizations of the incident microwave. We investigated dependencies on the operating frequency and the radius (R) of an arc of the arranged thirteen n-Si cylinders with the low semiconductor specific resistivity of 0.5, 2, and 10 Ω∙m. We have discovered that the arrays may have features of a waveguide or a microwave reflector.This article belongs to the Special Issue Photonic and Plasmonic Crystal
International Branch Campuses as an Entry Mode to the Foreign Education Market
No full textHigher education institutions (HEIs), especially latecomer institutions, continue to regard
exporting education services by creating a commercial presence in a foreign country with caution.
The purpose of this paper is to investigate ways of creating and managing international branch
campuses (IBCs) and to elaborate recommendations for universities on establishing a branch campus
as an entry into the foreign education market. In order to reach this aim, we analyse the trends of IBC
development in higher education in the last 30 years, compare the theory and concepts of service
export in business and in higher education and, finally, conduct a case study on seven IBCs globally.
The analysis shows clear synergy between business theory and higher education (HE); however,
no obvious coherence is discovered between the IBC establishment practices and the traditional
Uppsala internationalisation model used in international business practices. This research continues
by verifying the coherence of IBCs with the revisited Uppsala model based on the relationships and
market commitment.This article belongs to the Section Entrepreneurshi
Evaluation of the Influencing Factors on Job Satisfaction Based on Combination of PLS-SEM and F-MULTIMOORA Approach
No full textA primary issue that is being discussed nowadays in organizations is continuous improvement of the organization itself, because the procedure of periodic evaluation is an important tool to maintain the improvement of the organization. An essential factor in any organization is the human resources as a key asset to guide organizations to sustain their competitive advantages by employing particular knowledge and skills to form a comprehensive and sustainable human resource management. Evaluation of job satisfaction has become a part of the strategic approach toward incorporating business policies and human resource actions in modern day organizations. The current research study presents a novel hybrid validation framework to evaluate and appraise the factors influencing job satisfaction based on the fuzzy MULTIMOORA approach and partial least-squares path modeling (PLS-PM). The proposed fuzzy MCDM technique and statistical method validate each other to present an optimal assessment of influencing factors in job satisfaction. Eventually, a real-world case study in regard to influential factors in job satisfaction has been suggested in this study, to show that the proposed framework is a practical and accurate method to tackle an assessment problem in a real-world application of influencing factors in job satisfaction in a cross-industrial multi-national construction and geotechnical engineering organization in Iran.This article belongs to the Special Issue Multi-Criteria Decision-Making Techniques for Improvement Sustainability Engineering Processe
Prediction of Deflection of Reinforced Concrete Beams Strengthened with Fiber Reinforced Polymer
No full textThe article analyses the calculation of the deflection of reinforced concrete beams strengthened with fiber reinforced polymer. This paper specifically focuses on estimating deflection when the yielding of reinforcement is reached. The article proposes a simple method for calculating deflection that was compared with the experimentally predicted deflection. The carried out comparison has showed that the proposed method is suitable not only for the strengthened beams but also for the reinforced concrete beams with a varying reinforcement ratio. The suggested calculation method is based on the effective moment of inertia, such as the one introduced in the ACI Committee 318 Building Code Requirement for Structural Concrete (ACI318). The development of deflection was divided into three stages, and equations for the effective moment of inertia were proposed considering separate stages. In addition, the put forward equations were modified attaching additional relative coefficients evaluating a change in the depth of the neutral axis.This article belongs to the Special Issue Fiber Reinforced Polymers for Structural Strengthenin
Approaches to Risk Identification in Public–Private Partnership Projects: Malaysian Private Partners’ Overview
No full textThe complexity of public–private partnership (PPP) projects ensures that risks could emerge and spread in unpredictable ways if they are not well identified and managed. The emergence of PPP projects has brought major changes in the construction industry, the most notable being in procurement methods influencing risk allocation to private parties. Thus, it is crucial to have an effective risk management for public and private partners to eliminate or minimise risks. Formulating an effective risk management system is a crucial challenge faced by both of parties in order to minimise or optimise risks. The aim of this study was to investigate the process of risk identification of private partners in Malaysian PPP projects. Data were collected throughout a 2-month period using a survey with a sample of nine Malaysian companies engaged in PPP projects, and the survey results were analysed using mean scores. The findings indicate that due to a lack of knowledge and experience of Malaysian private partners in the risk identification process, a comprehensive database for risk identification is highly necessary for the private sector. Another issue emerging from the findings is that it may be reasonable to use a combination of risk identification tools for PPP projects with a high level of complexity. The findings of the present study can greatly assist public and private partners to select the most appropriate tools for risk identification at the early stages of PPP projects.This article belongs to the Special Issue Rational Decision Making in Risk ManagementThis research was funded by Universiti Teknologi Malaysia and the Ministry of Science, Technology
and Innovation (MOSTI) of Malaysia, ScienceFund, grant number 4S084
Bidirectional Piezoelectric Energy Harvester
Get PDFThis paper represents a numerical and experimental investigation of the bidirectional piezoelectric energy harvester. The harvester can harvest energy from the vibrating base in two perpendicular directions. The introduced harvester consists of two cantilevers that are connected by a particular angle and two seismic masses. The first mass is placed at a free end of the harvester while the second mass is fixed at the joining point of the cantilevers. The piezoelectric energy harvester employs the first and the second out of plane bending modes. The numerical investigation was carried out to obtain optimal geometrical parameters and to calculate the mechanical and electrical characteristics of the harvester. The energy harvester can provide stable output power during harmonic and impact-based excitation in two directions. The results of the investigations showed that energy harvester provides a maximum output power of 16.85 µW and 15.9 4 µW when the base has harmonic vibrations in y and z directions, respectively. Maximum output of 4.059 nW/N and 3.1 nW/N in y and z directions were obtained in case of impact based excitationThis article belongs to the Special Issue Energy Harvesting and Energy-Neutral IoT Devices and SystemsThis project has received funding from the European Regional Development Fund (project No
01.2.2-LMT-K-718-01-0010) under a grant agreement with the Research Council of Lithuania
Ranking of Heritage Building Conversion Alternatives by Applying BIM and MCDM: A Case of Sapieha Palace in Vilnius
No full textA balance (symmetry) between socio-cultural and socio-economic benefits as a part of the economic, social, and cultural development policy of each city and country should be assured when converting built heritage. To anticipate building conversion priorities and opportunities, modern technologies can be employed. However, currently the activity of reconstruction of heritage buildings is part of the construction domain wherein modern digital technologies have been the least ever applied. Therefore, photogrammetry and the 3D modeling of existing heritage buildings was suggested. A case study of Sapieha Palace, built in the Baroque style in 1689–1691 in Vilnius, Lithuania was explored in this research. The applied technologies and software (Agisoft Photoscan, Autodesk ReCap and Autodesk Revit) allowed for the creation of a high quality and accurate model involving both the textured exterior of the building and the interior layout. In addition, the valuable features of a building were identified and marked in a three-dimensional digital model. Based on the model, the authors formulated possible conversion alternatives of the building and identified the associated decision-making criteria, as well as determined their relative significance by an expert survey method. The authors suggested the application of the multiple criteria decision making (MCDM) method under uncertainty, namely the rough weighted aggregated sum product assessment (WASPAS), for ranking alternatives according to multiple criteria. Therefore, the suggested integration of modern digital technologies and decision-making models helps to assure the rational conversion decision of built cultural heritage based on high accuracy data as well as contributing to the sustainable development of engineering processes.This article belongs to the Special Issue Multi-Criteria Decision-Making Techniques for Improvement Sustainability Engineering Processe
Modelling the factors of a company’s sustainable development
Get PDFDisertacijoje sisteminiu požiūriu nagrinėjama įmonės darnios plėtros modeliavimo problematika, kuri yra itin aktuali įmonėms, nes šalies arba regiono darni plėtra neįmanoma be įmonių darnios plėtros. Darnios plėtros principų integravimas į veikiančių ar tik besikuriančių įmonių veiklą atveria didesnes galimybes įmonėms kurti naujus produktus, plėstis į naujas rinkas ir taip užsitikrinti ilgalaikę sėkmę. Tyrimų objektas – įmonės darnios plėtros veiksniai. Darbo tikslas yra sukurti įmonės darnios plėtros modelį, jungiantį darnios plėtros dimensijų turinį apibrėžiančius elementus ir veiksnius, kurių integravimas į įmonės veiklą padėtų įmonėms siekti darnios plėtros ir prisidėti prie globalių darnios plėtros tikslų įgyvendinimo.
Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados ir 8 priedai.
Pirmame disertacijos skyriuje išnagrinėtos darnios plėtros sąvokos semantinės interpretacijos, koncepcijos probleminiai aspektai, teorijos pagrindžiančios įmonės darnią plėtrą. Šiame skyriuje išsamiai pagrįstas poreikis įmonėms rinktis darnios plėtros kryptį, aptarta darnios plėtros nauda įmonėms, diskutuota apie naujo modelio kūrimo prielaidas. Antrajame disertacijos skyriuje trumpai pagrįstas modeliavimo kaip metodo pasirinkimas. Analizuojamas ir detalizuojamas kiekvienos dimensijos turinys, išskirti esminiai komponentai ir veiksniai, turintys įtakos įmonės darniai plėtrai. Skyriuje pateikiami sukurti aplinkosauginės, socialinės, technologinės, veiklos valdymo, ekonominės dimensijų modeliai bei įmonės darnios plėtros modelis, jungiantis penkias dimensijas. Trečiajame disertacijos skyriuje pateikta įmonės darnios plėtros modelio empirinio tyrimo metodika, sudaryta iš pasirengimo, tyrimo vykdymo ir rezultatų apibendrinimo etapų. Kriterijų reikšmingumams nustatyti atliktas ekspertinis vertinimas. Empirinis tyrimas vykdytas Lietuvos įmonėse, taikant struktūrinio interviu metodą. Tyrimo duomenys matematiškai apdoroti, naudojant paprastajį adityvų svorių metodą (SAW), kurio taikymas sudaro sąlygas darnios plėtros dimensijų veiksnių sujungimui į vieną apibendrintą įvertį, pagal kurį nustatytas tiriamųjų įmonių darnios plėtros lygis. Empirinio tyrimo rezultatai pagrindžia įmonės darnios plėtros veiksnių modelio pritaikomumą verslo įmonėse.Disertacij
Modification of cement concrete by wood biofuel fly ash
No full textCementbetonio gamyba yra susijusi su nemažomis energijos sąnaudomis. Energija vartojama ruošiant žaliavas, gaminant rišamąsias medžiagas, gaminius ir juos transportuojant. Gaminant cementą išsiskiria didelis kiekis CO2. Šiuo metu CO2 emisijos mažinimas cemento gamyboje yra viena iš prioritetinių krypčių Europos Sąjungoje ir visame pasaulyje. Todėl aktuali problema – cemento kiekio mažinimas cementbetonyje. Šiame darbe siekiama dalį cemento cementbetonyje pakeisti medienos biokuro lakiaisiais pelenais, taip pat nagrinėjamos taip modifikuoto cemetbetonio fizikinės ir mechaninės savybės.
Disertacijoje nagrinėjami medienos biokuro lakieji pelenai (MBLP), jų naudojimo galimybės cementbetonyje ir sprendžiami keli pagrindiniai uždaviniai: ištirti sijotų ir nesijotų medienos biokuro lakiųjų pelenų kiekio poveikį cementbetonio fizikinėms ir mechaninėms savybėms. Pagrindinė tyrimo tematika – medienos biokuro lakiųjų pelenų kiekio ir smulkumo įtaka cementbetonio savybėms.
Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai.
Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pateikiamos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose, taip pat disertacijos struktūra.
Pirmajame skyriuje atlikta literatūros nagrinėjama tema apžvalga. Analizuojami moksliniai tyrimai apie deginimo pelenus, aprašyti biokuro pelenų gavybos procesai. Šiame skyriuje aprašytas biokuro pelenų naudojimas cementbetonyje. Skyriaus pabaigoje formuluojamos išvados ir tikslinami disertacijos uždaviniai.
Antrajame skyriuje aprašytos tyrimams naudotos medžiagos ir jų pagrindinės charakteristikos, pateiktos mišinių sudėtys ir aprašyta, kaip buvo formuoti bandiniai. Pateikti tyrimų metodai ir pristatyta laboratorinė įranga.
Trečiajame skyriuje analizuojamos medienos biokuro lakiųjų pelenų savybės ir struktūra. Nagrinėjamos cementinio akmens ir cementbetonio fizikinės, mechaninės savybės. Pateikiami betono atsparumo šalčiui tyrimų rezultatai ir jų analizė. Taip pat pateikiami fizikinių ir mechaninių savybių pokyčiai modifikavus betoną.
Disertacijos tema paskelbti šeši moksliniai straipsniai ir perskaityti keturi pranešimai Lietuvos ir kitų šalių konferencijose.Disertacij