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Revised estimation of public railway infrastructure line capacity: Lithuanian case
No full textThe problematic of determination of maximum capacity of Lithuanian Railway lines is considered is this article. Maximum capacity considered the largest number of trains that could run over a railway line, during the scheduled time interval. At the same time, the train traffic should be ensured in a strictly perfect, mathematically defined environment, with the trains running permanently and ideally at minimum headway, i.e., keeping time-based distance between two consecutive trains. Current applied calculation methods and the means of Lithuanian train traffic arranging are revised by estimating the railway traffic irregularity due the features of technical equipment: traction vehicles, signalling, automatic, track, catenary, etc. The maximum potential capacities of three problematic lines of Lithuanian Railways are estimated taking into account the type and power of freight locomotives. Considered railway lines are: “Livintai - Gaižiūnai”, “Plungė - Šateikiai” and “Pagėgiai - Tauragė - Viduklė”. Finally, basic conclusions and recommendations are given
Burning out additives effect of ceramic psychical mechanical properties and structures
No full textGrūdų perdirbimo gamybos metu susidaro didelį kiekiai atliekų. Norint spręsti šią problemą, būtina ieškoti naujų būdų, kur gali būti panaudotos tokios atliekos. Pagrindinis darbo tikslas ištirti avižų lukštų ir miežių lukštų ir miltų mišinio atliekų panaudojimo kaip išdegančio priedo galimybes statybinės keramikos gamyboje. Formavimo masės buvo paruoštos įvedant 5 %, 10 % ir 20 % avižų lukštų ir miežių lukštų ir miltų mišinio priedo, išdegti 900 °C ir 1000 °C temperatūroje, išlaikant aukščiausioje temperatūroje 1 h. Atlikus tyrimus, rekomenduojama į formavimo mases įdėti iki 5 % avižų lukštų arba miežių lukšto ir miltų mišinio. Įdėjus tokį kiekį ir išdegant 900–1000 °C temperatūroje gauname keraminę šukę, kurios tankis – 1496–1638 kg/m³ ribose, gniuždymo stipris – 5,0–9,5 MPa, susitraukimas po degimo – 6,64 – 10,82 %, efektyvusis poringumas – 25,1–36,6 %, vandens įmirkis – 14,4–16,7 % Didesnis nagrinėjamų priedų kiekis žymiai mažina bandinių stiprį. Darbą sudaro 6 dalys: įvadas, literatūros apžvalga, tyrimų metodika, eksperimentinė dalis, išvados, literatūros sąrašas. Darbo apimtis: 49 p. teksto, 26 paveikslai, 7 lentelės, 52 bibliografiniai šaltiniaiThe use of agricultural waste as alternative raw materials for the manufacturing of building products, fired clay bricks in particular, is an innovative way of waste utilization. Large quantities of waste are produced in grain processing. New ways of utilizing this waste have to be found for solving this problem. The main objective of this study is to investigate the effects of agricultural solid waste (oat husk and barley husk and middlings) additives on the physical-mechanical properties and porosity of fired clay bricks. Brick moulding compounds were prepared by adding 5 %, 10 % and 20 % of oat husk or barley husk and middlings and fired at 900 °C and 1000 °C temperature, keeping them at the highest temperature for 1 hour. The addition of 5 % of oat husk or barley husk and middlings into brick moulding compound produces eco-friendly fired clay brick having the density of 1496–1638 kg/m³ , total shrinkage – 6,64–10,82 %, compressive strength of 5,0–9,5 MPa, effectyve porosity of 25,1–36,6 % water absorption – 14,4–16,7 %. 10-20 % oat husk or barley husk and middlings reduces the compressive strength of fired clay brick. Structure: introduction, research method, discussion, conclusions and suggestions, references. Thesis consist of: 49 p. text without appendixes, 26 pictures, 7 tables, 52 bibliographical entries
Biblioteka informuoja, 2023 Nr. 35 (627)
No full textNaujai į Web of Science ir Scopus įtrauktų Vilnius Gedimino technikos darbuotojų publikacijų sąrašai ir kitos bibliotekos aktualijos.35 (627)202
Construction Project Delay Risks and Their Management
No full textBaigiamajame magistro darbe nagrinėjami statybos projektų uždelsimo rizikos veiksniai, vertinama šalių patirtis šioje srityje. Pasitelkiant ekspertų atsakymus parinkti veiksniai įtakojantis statybos projektų uždelsimo rizikas. Sprendžiami du sudėtingi daugiatiksliai uždaviniai, kuriais siekiama nustatyti svarbiausias projektų uždelsimo rizikas. Išnagrinėjus teorinius ir praktinius statybos projektų uždelsimo rizikų aspektus, pateikiamos baigiamojo darbo išvados. Darbą sudaro įvadas, 3 skyriai, tyrimo išvados, literatūros sąrašas. Darbo apimtis – 67 p. teksto be priedų, 4 pav., 51 lent., 84 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai.The final master's thesis examines the factors contributing to the delay risks in construction projects and evaluates the experience of the parties involved in this field. By utilizing expert responses, the factors influencing the delay risks in construction projects are identified. The thesis addresses two complex multi-objective tasks aimed at identifying the most significant risks associated with project delays. After analysing the theoretical and practical aspects of delay risks in construction projects, the conclusions of the thesis are presented. The thesis consists of an introduction, three chapters, research conclusions, and a list of references. The scope of the work is 67 pages of text without attachments, including 4 figures, 51 tables, and 84 bibliographic sources. Additionally, the thesis includes separate attachment
Modelling and experimental verification of the interaction in a hydraulic directional control valve spool pair
No full textThis study examined the impact of mechanical oscillation on a hydraulic directional control valve. Particular attention was paid to the oscillating movement of the spool of the hydraulic directional control valve resulting from this impact. Different models of fluid and mixed friction were considered. The models analysed accounted for the relative movement of the directional control valve body and the fact that it is kinematically excited by external mechanical oscillations. It was observed that the mixed friction model, where the frictional force is considered to be the sum of molecular forces acting in micro-areas of contact and drag forces in the fluid, was the best for describing the movement of the spool for a specific spool oscillation frequency. This model yielded significantly more consistency between the simulated and experimental results than the classic fluid friction model.iss. 1vol. 1
Investigation of Nonlinears PI Control Algorithm and its Implemantation in the Embedded System
No full textBaigiamojo magistro darbo tikslas – ištirti nPI valdymo algoritmą ir suprojektuoti įterptinę sistemą, naudojančią šį algoritmą. Tyrimui atlikti nPI valdiklis palyginamas su PID ir PI valdikliais. Įterptinei sistemai naudojamas STM32f1 serijos mikrovaldiklis. Darbą sudaro: įvadas, teorinė apžvalga, dalinė išvada, valdymo algoritmų palyginimas „Simulink“ aplinkoje, realios įterptinės sistemos testavimo rezultatai, apibendrinančios išvados, literatūros šaltinių sąrašas ir priedai. Teorinėje dalyje aptariamos nPI valdiklio savybės. Praktinėje dalyje aptartos savybės tikrinamos modeliuojant „Simulink“ aplinkoje, taip pat pasitelkiant suprojektuotą įterptinę sistemą. Aptariami gauti duomenys, suformuluojamos išvados. Darbo apimtis: 40 puslapių be priedų, 20 iliustr., 6 lent., 10 bibliografinių šaltinių.nPI control algorithm and its embedded system is being reviewed in this master’s thesis. nPI controller is compared to PID and PI controllers. For embedded system STM32F1 series microcontroller was chosen. The thesis consists of: introduction, theoretical review, partial conclusion, comparison of nPI, PID and PI controllers using Simulink software, the results of designed embedded system, final conclusion, references and appendices. Firstly, theory of control algorithms is analyzed. Secondly, advantages and disadvantages of all three controllers tested in Simulink and the in real life conditions using design embedded system. The gathered data is then analyzed and summarized. This thesis contains 40 pages of text (excluding appendices), 20 pictures, 6 tables and 10 references cited
Study of the forecasting methods for road traffic
No full textBaigiamajame magistro darbe nagrinėjami kelių transporto priemonių eismo srautų prognozavimo metodai. Analitinėje dalyje apibūdinta eismo valdymo specifika, apžvelgti populiariausi naivieji, parametriniai ir neparametriniai prognozės modeliai. Atlikta mokslinės literatūros analizė. Tiriamojoje dalyje nagrinėtas parametrinių bei neparametrinių modelių taikymas prognozuojant trumpalaikius eismo srautus. Įvertinti reikalavimai pradiniams duomenims. Sudarytos penkiolikos minučių eismo intensyvumo prognozės. Modeliai validuoti prognozes palyginus su realiais duomenimis. Įvertintas sudarytų modelių tikslumas, greitaveika, geba vertinti skirtingų eismo juostų intensyvumą. Įvertintas modelių tikslumas atliekant skirtingo laikotarpio prognozes. Išbandytas glodinimo metodų taikymas siekiant sumažinti pradinių duomenų triukšmą. Pateiktos rekomendacijos galimam prognozės metodų taikymui. Darbą sudaro 6 dalys: įvadas, analitinė dalis, prognozės modelių tyrimo metodika, eismo srautų prognozės tyrimas, išvados ir siūlymai, literatūros sąrašas. Darbo apimtis – 104 p. teksto be priedų, 44 iliustr., 19 lent., 31 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai.The master thesis presents study of the forecasting methods for road traffic. Concept of the short–term forecasting methods application for traffic light controlled intersections cycle optimization is addressed in the analytical part. Analytical part explores naive, parametric and nonparametric forecasting methods and identifies these models ability to forecast with real time data. Based on the literature overview, SARIMA model is chosen for further investigation. In the methodology part of this paper, definition of SARIMA method and model construction is described. SARIMA model application with real data is presented in the research part of this paper. Forecast of fifteen minutes traffic flow accuracy is evaluated. For comparison purpose, SARIMA model forecasts are compared with LSTM models. Models ability to forecast different time horizon and application versatility is evaluated. Smoothing methods were used in order to address noisy primary data of the road traffic. As a result, accurate forecast characteristic are described and recommendations for further investigation and application are proposed. Thesis consist of the following parts: introduction, analytical review of the forecasting methods and intersection control, research methodology, short–term forecasting methods research, conclusion and proposals, list of references. Thesis consists of: 104 pages of text without appendixes, 44 illustrations, 19 tables, 31 bibliographical entries. Appendixes included
Kraštovaizdžio architektūros prasmių interpretacijos: kraštovaizdžio architektūros ir daiktinės aplinkos kokybės vertinimo aspektas
No full textNr.
The Socio-educational Theory of the “Invisible Hand” /
No full textThe Socio-educational Theory of the “Invisible Hand” is the result of the research using constructivist grounded theory strategy. The socio-educational factors of recreational activities carried out in regional open youth centres/spaces were investigated. The study has included young people with fewer opportunities (YPFO) aged 16–20 and the youth workers. The study started in January and ended on September 2021. In the research data analysis, the recurring word “invisible” was noted, bringing up the image of the “invisible hand”. The metaphor of the “invisible hand” was used to visualize, understand and explain the process of social education through recreation. The constructed grounded theory – the Socio-educational Theory of the “Invisible Hand”, was linked to the economical theory of the Invisible Hand described by the economist A. Smith (1776). It has been revealed that it is a process consisting of visible and invisible sub-processes running simultaneously. The invisible one is not direct or pre-planned. It is a process that can be accidental or conscious, spontaneous or purposeful.vol. 1
