Vilnius Tech DSpace Repository
Not a member yet
52562 research outputs found
Sort by
Implementing intelligent monitoring of the technical condition of locomotive hydraulic transmissions
No full textThe study is aimed at replacing outdated approaches in the organization of maintenance of the locomotive fleet. The article presents a comparative analysis of maintenance strategies for traction rolling stock. The necessity of introducing control over the technical condition of locomotives to ensure the transition to a preventive maintenance system is substantiated. Directions of research - adjustment of the existing volumes and frequency of repairs, the introduction of individual repair strategies, the introduction of adapted and flexible approaches to the maintenance of locomotives. To improve the efficiency of monitoring the technical condition of locomotives, the use of factor analysis methods is proposed. The purpose of using factor analysis methods is to reduce the number of analysed parameters, while the information content of monitoring the technical condition should not decrease. The results of applying the method of principal components to assess the technical condition of the hydraulic transmission of a diesel locomotive during testing are presented. It is proposed to use the concept of latent diagnostic parameters to assess the technical condition of locomotive units. Considering the physical meaning of the processes occurring in the hydraulic transmission, as a result of the analysis, three groups of latent parameters were identified: “Load”, “Losses”, “Input”. These parameters characterize the technical condition of the hydraulic transmission. Each of the latent parameters includes information from a group of physical process sensors. The implementation of the considered approach will ensure the effective use of monitoring results and a gradual transition to predictive maintenance
Evaluation of fruit yield in automatic harvesting systems using mechanical vibration analysis
No full textThe article proposes an assessment of the quantitative parameters of the crop using the analysis of mechanical vibrations. A demonstration of the investigation is shown for a situation where a support system in the field helps cucumbers grow vertically. The study was carried out by model- ing the yield of cucumbers. The greatest attention was paid to the frequencies of natural oscilla- tions. A developed numerical model of the support design is proposed and its natural oscillation frequencies are calculated using the finite element method (FEM). The results were confirmed by a physical experiment that actually simulates a numerical model.iss. 00vol. 0
Investigation on Development and Funding of Innovative Industrial Companies
No full textŠiame baigiamajame magistro darbe nagrinėjami metodai ir pasirinkimų priežastys kurios padėtų sėkmingai vystyti inovatyvių gamybos įmonių veiklą. Pateikiamos pagrindinė sąvokos, apibrėžiamos inovacijos ir idėjų apsaugos būdai, apžvelgiama pramonės įmonių ir inovatyvių produktų raida, taip pat daugiau dėmesio skiriama invatyvių gamybos įmonių finansavimo šaltiniams ir jų poreikiui. Naudojantis išoriniais šaltiniais pasirenkamos sėkmingos inovatyvios gamybos įmonės kurios vėliau apklausiamos naudojant anketinę formą. Gauti duomenys apdoroti naudojant lyginamąją duomenų analizę, taip išryškinant panašumus ir skirtumus tarp įmonių pasirinkimų. Remiantis surinkta informacija pateikiami autoriaus sukurti modeliai kurie apibrėžia žingsnius kurie gali padėti savo veiklą pradedančioms inovatyvioms gamybos įmonėms. Kartu su modeliais pateikiamos išvados ir rekomendacijos. Darbą sudaro: įvadas, inovacijų ir idėjų apsauga, pramonės įmonių ir produktų raida, inovatyvių gamybos įmonių finansavimo poreikis, inovatyvių gamybos įmoniųtyrimo metodika, inovatyvių gamybos įmonių finansavimo ir plėtros galimybių tyrimas, sėkmingos įmonės modelis, išvados ir pasiūlymai. Darbo apimtis – 62 p. teksto, be priedų, 8 iliustr., 46 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai.This master thesis analyzes the methods and reasons for choices that would help to successfully develop innovative manufacturing companies. The main concepts are outlined, innovations and ways of protecting ideas are defined, development of industrial enterprises and innovative products is reviewed, as well as more attention is directed to the sources of financing of the inovative manufacturing companies and their needs. Successful innovative manufacturing companies are selected using external sources and then questioned using a questionnaire form. The obtained data was processed using comparative data analysis, thus highlighting similarities and differences between company choices. Based on the information gathered, author presents models that define the steps that can help start-up innovative manufacturing companies. Together with the models, conclusions and recommendations are presented. Structure: introduction, protection of innovations and ideas, development of industrial enterprises and products, financing of innovative production enterprises, research methodology of innovative production enterprises, research of financing and development opportunities of innovative manufacturing enterprises, successful company model, conclusions and suggestions. Thesis consist of 62 p. text, without appendixes, 8 pictures, 46 bibliographical entries. Appendixes are added separately
Assessment of the interaction of the logistics company’s information technologies with the technological infrastructure
No full textThe continuously changing market of companies offering logistics services has challenged logistics organizations to adapt to the needs of service users and providers. Faster information processing offers new ways of communication with suppliers and optimization of distribution systems. Increasing information flows have an increasing potential to affect the management, structure, functioning and development of enterprises. The development of technological infrastructure and information technology systems by organizations allows service participants to exchange information, adjust information flows and restore relevant information through the use of technology, which poses new challenges for resource management. The level of innovation of production processes, productivity and the quality of products directly depends on the transmission of information and technology. To successfully work in the existing market, organizations must not only purchase IT systems or technologies but also constantly upgrade system applications, improve technologies or acquire brand-new IT systems. The article analyses the peculiarities of the impact of the development of technological infrastructure and its use as an instrument for the development of logistics organizations and quality assurance of logistics services. The quality research carried out allowed identifying the problems relating to technological infrastructure in logistics organizations.iss. 1vol. 2
The impact of high-alkali biofuel fly ash on the sustainability parameters of concrete /
No full texthe results of this research show that high-alkali biofuel fly ash (BFA) had a significant influence on the mechanical characteristics, microstructure, porosity, freezing–thawing cycle resistance, and ASR resistance of cementitious materials. Different amounts of BFA (varying from 0 to 30%) were used as a substitute for cement in concrete mixes. The impact of substituting cement with BFA on the cement hydration products was analysed. Slump behaviour, mechanical properties, water absorption, porosity, freeze–thaw cycles, and ASR resistance were studied. The analysis of the mechanical and physical characteristics of the developed sustainable concrete revealed that a better structure, higher compressive and flexural strength and density values, and better freeze–thaw and ASR resistance as well as lower water absorption values were achieved when as much as fifteen percent of cement was substituted with high-alkali BFA. The calculations indicate that the substitution of cement with different quantities of high-alkalinity BFA (from 0% to 30% BFA) increased the SiO2/CaO ratio from 0.32 to 0.51 and the Na2O + K2O/CaO ratio from 0.02 to 0.067 in the composition. An evident higher quantity of the hydration products, reflected in the reduction of porosity by up to 27%, the improvement in compressive strength by up to 19.3%, and the calculated freeze–thaw resistance value of up to 51.50%, was observed when the Na2O + K2O/CaO ratio did not exceed 0.044. The ASR resistance of the concrete improved with the increase in the Na2O + K2O/CaO ratio. This study shows that BFA with high alkalinity is beneficial in the development of sustainable building materials.iss. 12vol. 1
Investigation of Vision Analysis Techniques for Cap Position Inspection
No full textŠiame baigiamajame magistro darbe analizuojamas konvoliucinių neuroninių tinklų pritaikymas automatinėse kokybės kontrolės sistemose. Darbo metu, naudojant atvirojo kodo bibliotekas, sukuriami 3 tiesioginio sklidimo konvoliuciniai neuroniniai tinklai, kurie išbandomi tikrinant butelio kamštelio padėtį. Šiems tinklams apmokyti naudojamas specialiai šiai užduočiai surinktas pavyzdžių rinkinys. Pavyzdžių rinkinį sudaro į tris klases suskirstytos 320×240 pikselių raiškos nuotraukos su gerai užsuktais ir netinkamai užsuktais butelių kamšteliais bei nuotraukos su buteliais be kamštelių. Siekiant kompensuoti nedidelį tinklams apmokyti skirtą duomenų kiekį ir pagerinti neuroninių tinklų pasiekiamus rezultatus, šio darbo metu taikomas dirbtinis duomenų papildymas. Darbo metu naudojant vieną iš sukurtų konvoliucinių neuroninių tinklų pasiektas 98 % klasifikavimo tikslumas ir 119 vaizdų per sekundę greitaveika rodo, kad tiesioginio sklidimo konvoliuciniai neuroniniai tinklai turi potencialo būti naudojami automatiniuose kokybės kontrolės įrenginiuose. Darbą sudaro 8 dalys: įvadas, vaizdinių duomenų bazės kūrimas, kamštelio padėties tikrinimo algoritmų kūrimas ir apmokymas, sukurtų algoritmų palyginimas, išvados, literatūros sąrašas ir priedai. Darbo apimtis – 49 p. teksto be priedų, 27 iliustr., 10 lent., 27 literatūros ir duomenų šaltiniai. Atskirai pridedami darbo priedai.This final master thesis analyzes the application of convolutional neural networks in automatic quality control systems. In this work, 3 direct-propagation convolutional neural networks are created using open source libraries. These networks are tested by checking the bottle cap position. A set of samples collected specially for this task is used to train these networks. The sample set consists of 320 x 240 px resolution photos that are divided into three classes: bottles well-screwed and misplaced bottle caps and photos with cap-free bottles. To compensate the small amount of neural network training data and improve neural network classification accuracy, a data augmentation algorithm is implemented. Using one of the neural networks, classification accuracy of 98% and throughput of 119 images per second has been reached. This suggests that neural networks have the potential to be used in automatic quality control systems. Structure: introduction, introduction, analytic part, design part, electrical security, investigation of results, conclusions and suggestions, references, graphical part. Thesis consist of: 49 p. text without appendixes, 27 pictures, 10 tables, 27 bibliographical entries. Appendixes included
Le espressioni artistiche degli interni delle chiese gesuitiche in Lituania
No full textBaigiamajame magistro darbe yra nagrinėjamos baroko stiliaus išsivystymo prielaidos, jėzuitų meninės raiškos modelio susikūrimas ir jo taikymas Lietuvos jėzuitų bažnyčių atvejais. Analizuojamas Jėzuitų ordino bažnyčių interjerų Lietuvoje meninės raiškos pobūdis, siekiant identifikuoti bažnyčioms būdingus interjerų plano kompozicijos ir meninius bruožus formos ir turinio sąryšio kontekste bei įvardinti kultūrinį ir religinį reikšmingumą. Nuosekliai sudarytas jėzuitų bažnyčių Lietuvoje sąrašas ir atskleisti atrinktiems objektams būdingi interjerų meninės raiškos ypatumai, lyginant juos tarpusavyje bei su Jėzuitų ordinui svarbiausios Romos Il Gesù bažnyčios modeliu. Išanalizuota kiekvienos bažnyčios dabartinė būklė, apžvelgti pokyčiai ir rekonstrukcijos, bažnyčių planinė kompozicija ir interjerus formuojantys elementai bei temos. Pasirinktos bažnyčios tirtos lyginamosios analizės būdu istoriniu, urbanistiniu, plano kompozicijos, meninių raiškos priemonių ir ikonografiniu vertinimo aspektu. Pateikiamos baigiamojo magistro darbo išvados, leidžiančios išskirti bažnyčias, turinčias daugiausiai reikšmingiausių bruožų, atrinktų pagal Romos Il Gesù bažnyčios modelį. Atkreipiamas dėmesys į jėzuitų paveldo išsaugojimo svarbą dėl unikalaus estetinio-meninio suvokimo. Darbą sudaro aštuonios dalys: įvadas, trys dėstymo dalys, išvados ir siūlymai, literatūros sąrašas, iliustracijų sąrašas, priedai. Darbo apimtis – 84 p. teksto be priedų, 46 iliustr., 1 lent., 114 bibliografinių šaltinių. Atskirai pridedami darbo priedai (iliustracijos ir lentelės).The final master thesis examines the background of the development of the baroque style, expansion of the model of Jesuit artistic expression and its application on the cases of Lithuanian Jesuit churches. The study analyses the character of the artistic expression of the interiors of churches of the Jesuit Order in Lithuania in order to identify the spatial and artistic features of interiors in the context of relation between the form and content as well as to determine the cultural and religious significance. Reasonable cases of the Jesuit churches were selected for being able to detect the patterns of the peculiarities of the artistic expression of interiors, comparing them with each other and with the model of the most important church for the Jesuit Order – Il Gesù church in Rome. The research analyses the current status of each church, the reconstructions and restorations through different periods, the spatial composition and the elements likewise the iconographic topics defining the interiors of the churches. For the study was used the comparative analysis of historical situations, urban character, artistic expression and iconographic aspects. The conclusions of the thesis permit to distinguish Lithuanian churches with the most essential features selected according to the model of the church of Il Gesù in Rome. Furthermore, the attention is drawn to the importance of the preservation of the Jesuit heritage due to the unique aesthetic perception. Structure: introduction, three chapters, conclusions and suggestions, references. Thesis consist of: 84 p. text without appendixes, 46 pictures, 1 table, 114 bibliographical entries. Appendixes included.La tesi analizza le condizioni dello sviluppo dello stile barocco, l’evoluzione del modello artistico dei gesuiti e la possibile applicazione ai casi di chiese gesuitiche in Lituania. Lo studio osserva la natura della espressione artistica degli interni delle chiese gesuitiche nel territorio lituano con il confronto di analisi delle prime e più importanti chiese della Compagnia di Gesù in Italia e in ex-regione della Confederazione Pollaca-Lituana. Coerentemente sono state selezionate delle chiese lituane potenzialmente analizzabili. L'obiettivo principale di questa ricerca è quello di analizzare le caratteristiche specifiche delle chiese gesuitiche in Lituania mantenendo l'attenzione sull’intero contesto culturale-artistico, oltre che osservare i temi artistici e iconografici principali e dei modelli di organizzazione spaziale degli interni. Le chiese selezionate sono state analizzate attraverso l’analisi comparativa degli aspetti storici, la situazione urbana, l’espressione artistica e l’aspetto iconografico. La tesi presenta risultati dello studio che permette di distinguere le chiese che hanno le caratteristiche più significative identificate dal modello di chiesa Il Gesù a Roma. Inoltre l'attenzione è attirata sull'importanza della conservazione specifica del patrimonio culturale della Compagnia di Gesù con particolare concentrazione sulla percezione estetico-artistica. Struttura: introduzione, tre capitoli, conclusioni, riferimenti. Tesi consiste di 84 pagine di testo (appendice escluso), 46 illustrazioni, 1 tabella, 114 voci di bibliografia. Appendice incluso
Application of Chemical Extraction Method for Heavy Metal Polluted Soil Treatment
No full textBaigiamajame magistro darbe nagrinėjamas cheminės ekstrakcijos metodo taikymas sunkiaisiais metalais užteršto dirvožemio valymui naudojant organines vyno, acto ir citrinos rūgštis. Darbas susideda iš 4 skyrių. Pirmajame analizuojami užsienio šalių mokslininkų atlikti ekstrakcijos tyrimai ir jų rezultatai, apžvelgiamos ekstrakcijos procesui ir efektyvumui aprašyti taikomos modeliavimo programos, pateikiami užsienio autorių sudaryti ekstrakcijos modelių pavyzdžiai. Antrajame skyriuje aprašoma tiriamojo darbo metodika – dirvožemio mėginių imties sudarymas, dirvožemio fizinių-cheminių parametrų nustatymas, mėginių paruošimas ekstrakcijos tyrimams, užteršimas sunkiaisiais metalais (Cu, Zn, Ni, Cr). Remiantis užsienio mokslininkų tyrimų praktika ir taupant išteklius cheminės ekstrakcijos tyrimas suskaidytas į atskiras stadijas, kurių metu nustatoma tam tikrų ekstrakcijos parametrų (rūgšties koncentracijos, laiko, temperatūros, pH, anglies kiekio dirvožemyje) įtaka jos efektyvumui. Trečiajame skyriuje pateikiami tyrimo rezultatai, apibūdinti nustatyti optimalūs parametrai su kuriais pasiekiamas aukščiausias ekstrakcijos efektyvumas, aprašomos pastebėtos tendencijos, pateikiamos tyrime gautos išvados. Ketvirtajame skyriuje atsižvelgiant į tyrimo metu sukauptus duomenis statistine-matematine programa „R statistical package“ atliekama regresinė analizė, kiekvienai iš tiriamųjų rūgščių sudaromi ekstrakcijos efektyvumą apibūdinantys modeliai, kurie naudoti sprendžiant optimizavimo uždavinius „MathCad“ matematine programa. Atliekant tyrimą ištirta daugiau kaip 135 dirvožemio mėginiai, baigiamąjį magistro darbą sudaro 144 puslapiai teksto, 72 paveikslai, 67 lentelės, 97 literatūros šaltiniai.Master thesis analyses chemical extraction method using tartaric, vinegar and citric acid. Chemical extraction is applied for heavy metal contaminated soil cleaning. Work consists of 4 chapters. The first one analyses extraction tests carried out by foreign scientists, describes their results, provides an overview of the method efficiency and presents simulation programs used by other scientists to create chemical extraction models. The second chapter describes planned experiment and it’s methodology - selection of soil samples, determination of soil physico-chemical parameters, sample preparation for extraction tests, soil contamination using heavy metals (Cu, Zn, Ni, Cr). According to foreign scientists researches and practices of resource saving, chemical extraction tests were classified into separate steps in which certain parameters (acid concentration, extraction time, temperature, pH, carbon content in the soil) are investigated, which makes influence of extraction efficiency. The third chapter presents study results. Optimal parameters with which the highest extraction efficiency was achieved, trends and findings obtained during the study are disscussed. In the fourth chapter collected data is processed using mathematical and statistical program R statistical package. For each of the tested acids regression analysis is performed. Formed extraction efficiency models used in solving optimization problems using mathematical MathCad application. The study examined more than 135 soil samples. The final master's work consists of 144 pages of text, 72 figures, 67 tables, 97 references
Development of composite acoustic panels of waste tyre textile fibres and paper sludge
No full textSince society is moving towards sustainable development, interest in secondary use of waste has recently become significant. This paper investigates a process to develop an acoustic material, using two types of waste. Composite acoustic panels were developed using waste tyre textile fibres (WTTF) and paper sludge (PS), and polyvinyl acetate (PVA) were used as a binder. Nonacoustic (bulk density, airflow resistivity) and acoustic (sound absorption coefficient, sound transmission loss) parameters were studied. Composite acoustic panels with different proportions of WTTF/PS/PVA (sixteen samples) were subjected to testing for the sound absorption coefficient according to ISO 10534-2 and sound transmission loss according to ASTM E2611. The density of all samples varied between 155.2 and 709.9 kg/m3, the thickness between 14.4 and 20.5 mm, and the airflow resistivity between 29.5 and 101.5 kPa∙s/m2. The results reveal that the proportion of various waste materials in mixtures can improve the acoustic performance of panels. The combination that gives the highest αavg. with a value of 0.50 was experimentally found to be 70% WTTF mixed with 15% PVA and 15% H2O. The average sound absorption coefficient with a value of 0.46 was also found to be 25% WTTF mixed with 25% PS and 25% PVA and 25% H2O. In sound transmission loss, the most effective was 50% PS and the 50% PVA composite, the TLeq was 28.3 dB, while the composites together with 30% WTTF, 20% PS and 25% PVA, and 25% H2O showed 18.9 dB loss. The results obtained using WTTF and/or PS wastes are attractive and show great and promising development potential.iss. 3vol. 1
Planarinių mikrobangų diodų A3B5 puslaidininkinių junginių pagrindu detekcinių savybių tyrimai milimetrinių bangų ruože
No full textSuccessful development of microwave technologies requires electromagnetic detectors capable of sensing high frequency signals at low levels of microwave power. Bulk barrier planar microwave diodes operating based on the major carrier phenomena are promising in high frequency electromagnetic radiation sensing applications. The dissertation aimed to develop and investigate new original planar microwave diodes with a lower spread of their electrical parameters and capable of detecting an electromagnetic signal in the millimeter wavelength range. The first chapter reviews the physical properties of microwave diode based detectors with quasi linear and non linear current voltage characteristics and microwave diodes with a two dimensional electron gas channel. Then, the application technologies for microwave detectors and methods for their investigation using appropriate probing systems are discussed. The second chapter covers the aspects of the development of planar semiconductor microwave diodes based on GaAs, AlGaAs, and AlGaAs/GaAs compounds. Next, the methodology for investigation methods of electrical parameters and detection properties of the microwave diodes is presented. The third chapter presents the results of experimental investigations of the electrical parameters and detection properties of planar dual microwave diodes based on a semi insulating or low resistivity GaAs substrate, including current voltage characteristics, detected voltage on power characteristics and dependence of voltage sensitivity on frequency in the millimeter wavelength range. The fourth chapter presents theoretical estimations and experimental investigations of the electrical and detection properties of bow tie type microwave diodes with partial gate above a two dimensional electron gas channel based on a selectively doped GaAs/AlGaAs heterostructure. The dissertation presents new developed planar microwave diodes, advanced techniques for investigating their properties, and ways for enhancing their detection properties. Five scientific papers were published on the topic of the dissertation: three papers in scientific journals included in the list of Clarivate Analytics Web of Science database with an impact factor, and two papers in conference proceedings included in the Clarivate Analytics Web of Science and Scopus databases. A European patent based on the results of the dissertation has been granted, and twelve reports, including the results of the dissertation, were presented at national and international scientific conferences.Norint sėkmingai vystyti mikrobangų technologijas reikalingi elektromagnetinės spinduliuotės detektoriai, galintys aptikti silpnus aukštadažnius signalus. Mikrobangų diodai su energetiniu barjeru puslaidininkio tūryje, kurių veikimas pagrįstas pagrindinių krūvininkų reiškiniu, yra perspektyvūs aukštųjų dažnių elektromagnetinės spinduliuotės detekcijos taikymų srityje. Šios disertacijos tikslas buvo sukurti naujus originalius planarinius mikrobangų diodus puslaidininkinių heterodarinių pagrindu, kurie pasižymėtų mažesniu elektrinių parametrų išbarstymu ir galėtų detektuoti elektromagnetinę spinduliuotę milimetrinių bangų ruože. Pirmajame skyriuje apžvelgiami mikrobangų detektorių su kvazitiesinėmis ir netiesinėmis voltamperinėmis charakteristikomis bei mikrobangų diodų su dvimačiu elektronų dujų kanalu fizikiniai parametrai. Taip pat aptariamos mikrobangų detektorių taikymo technologijos ir aptariami jų parametrų matavimų būdai naudojant zondavimo sistemas. Antrajame skyriuje aprašomi planarinių mikrobangų diodų GaAs, AlGaAs ir AlGaAs/GaAs pagrindu kūrimo etapai ir procesai bei pateikiamos jų elektrinių parametrų ir detekcijos savybių tyrimo metodologijos. Trečiajame skyriuje aprašomi planarinių mikrobangų diodų ant laidaus GaAs padėklo bei planarinių mikrobangų AlGaAs diodų ant pusiau izoliuojančio padėklo elektrinių parametrų ir detekcijos savybių eksperimentinių tyrimų rezultatai: voltamperinės charakteristikos, voltvatinės charakteristikos, voltvatinio jautrio dažninės priklausomybės milimetrinių bangų ruože. Ketvirtajame skyriuje aprašomi peteliškės formos mikrobangų diodų su daline sklende virš dvimačio elektronų dujų sluoksnio AlGaAs/GaAs selektyviai legiruotame heterodarinyje elektrinių parametrų ir detekcijos savybių eksperimentiniai tyrimai ir teorinis įvertinimas. Disertacijoje aprašomi nauji sukurti mikrobangų diodai, pasiūlomos pažangios jų tyrimo metodikos ir būdai leidžiantys pagerinti diodų detekcijos savybes. Pagrindiniai disertacijos rezultatai buvo paskelbti 5 mokslo straipsniuose: 3 – mokslo žurnaluose, įtrauktuose į Clarivate Analytics Web of Science duomenų bazės sąrašą su citavimo rodikliu, 2 – tarptautinių konferencijų medžiagoje, įtrauktoje į Clarivate Analytics Web of Science ir Scopus duomenų bazes. Disertacijoje atliktų tyrimų rezultatai buvo paskelbti 12 mokslinių konferencijų Lietuvoje ir užsienyje. Gautas Europinis patentas remiantis disertacijoje pateiktais rezultatais