Vilnius Gediminas Technical University
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Research on the accuracy of algorithms for autonomous aircraft navigation
Get PDFDisertacijoje nagrinėjamos nedidelių autonominių orlaivių navigacijos algoritmų įtakos skrydžio tikslumui bei orlaivio deviacijos nuo užduotos skrydžio trajektorijos vertinimo problemos. Pagrindinis tyrimų objektas yra autonominės navigacijos algoritmai. Autonominio skrydžio tikslumas yra tiesiogiai susijęs su skrydžio sauga. Dėl šios priežasties pagrindinis disertacijos tikslas yra ištirti naudojamus ar siūlomus naudoti navigacijos algoritmus bei pateikti autonominio skrydžio saugos gerinimo metodus per navigacijos prizmę.
Darbe sprendžiami trys pagrindiniai uždaviniai: autonominio orlaivio navigacijos matematinio modelio parinkimas bei matematinis aprašymas, navigacijos algoritmų įtakos skrydžio tikslumui vertinimas, mažesnę įtaką skrydžio nuokrypiams turinčio algoritmo sukūrimas, kurio paskirtis – saugiai apskristi ir išvengti antžeminių kliūčių. Pirmasis uždavinys skirtas įvertinti didelės imties navigacijos duomenų statistinę aibę. Antrasis bei trečiasis skirti pačių algoritmų analizei.
Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados, literatūros ir autoriaus publikacijų disertacijos tema sąrašai ir šeši priedai.
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. Įvade pateiktos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra.
Pirmasis skyrius skirtas literatūros analizei. Jame pateikta autonominių orlaivių klasifikacija. Pateikta autonominių orlaivių navigacijos, kontrolės bei valdymo algoritmų analizė. Skyriaus pabaigoje formuluojamos išvados ir tikslinami disertacijos uždaviniai.
Antrajame skyriuje pateiktas tyrimuose taikomas matematinis autonominio orlaivio navigacijos modelis. Pateikta šiuo modeliu gautų navigacijos duomenų analizė bei vertinimas.
Trečiajame skyriuje teoriniai rezultatai lyginami su gautais praktinių skrydžių metu bei naudojant SITL (angl. Software In The Loop) skrydžio imitaciją. Pasiūlyta metodika bei autonominių orlaivių navigacijos algoritmas automatizuotam antžeminių kliūčių apskridimui.
Disertacijos tema paskelbti 6 straipsniai: du – straipsniai žurnaluose, įtrauktuose į Thomson ISI duomenų bazę, du – recenzuojamuose žurnaluose kitose duomenų bazėse, bei du – kitų tarptautinių bei respublikinių konferencijų medžiagoje. Disertacijos tema perskaityti 6 pranešimai Lietuvos bei kitų šalių konferencijose
Medis architektūroje – medžiagos metamorfozės
No full textStraipsnyje tyrinėjamos medžio medžiagos ir imitavimo reiškinio architektūroje sąsajos. Imitacijų taikymas
architektūros eksterjeruose, interjeruose yra menkai profesionalų ir visuomenės nagrinėta problema, ir tai
neretai lemia diskutuotinų sprendimų priėmimą kūryboje. Mes nė nesusimąstome, kad kasdienėje šalia
esančioje architektūroje esama paviršių, kurie atrodo kaip patraukli, natūrali ar madinga medžiaga, bet iš
tikro tai kita materija, originalo imitacija, tik autentiškos medžiagos atvaizdas. Analizuojamos dvi imitavimo
reiškinio formos. Pirmoji – kai iš medžio padarytas, sukonstruotas architektūros objektas ar jo detalės
vaizduoja, „apsimeta” kitos medžiagos statiniu. Antrasis variantas atvirkštinis – kai kita medžiaga imituojamas
medis. Kiekvienu atveju susiduriama su didele pavyzdžių gausa, imitacijos ir tikrosios medžiagos
panašumo laipsniu. Abi imitacijų formos, nepaisant jų kontroversiškumo, liudija ypatingą tikrojo medžio
kaip medžiagos patrauklumą architektūroje
Evaluation of advertising campaigns on social media networks
No full textAs the virtual environment is constantly changing, not only users’ informational and
knowledge needs but also the means and channels of communication with customers applied by
organizations change. There is a noticeable trend to move more and more advertising campaigns to
social media networks because of the opportunities they provide to organizations and users, which
results in the ever-increasing popularity of social media networks and a number of their users. Such a
transition is explained by one of the main objectives organizations have: to inform their customers in
an appropriate way and receive feedback on social media networks, which is difficult when traditional
advertising channels and means are applied. Since advertising campaigns on social media networks
are evolving rapidly, their assessment factors and methods, which receive controversial opinions in
both scientific literature and practice, change too. Researchers assess and interpret the factors that
influence the effectiveness of advertising campaigns on social media networks differently. Thus, a
problem arises: how should we evaluate which approach is more capable of accurately and fully
reflecting and conveying reality? In this research, this problem is studied by connecting approaches
of different researchers. These approaches are linked to the effectiveness assessment of advertising
campaigns on social media network aspects. To achieve the objective of this study, such research
methods as analysis of scientific literature, multiple criteria and expert assessment (a structured
survey and an interview) were applied. During the study, out of 39 primary assessment factors, eight
primary factors that influence the effectiveness of advertising campaigns on social media networks
were identified: sales, content reach, traffic to website, impressions, frequency, relevance score, leads
and audience growth
Sustainable construction industry in Cambodia: awareness, drivers and barriers
No full textAlthough sustainability is of utmost importance, anecdotal evidence suggests that the
concept is not adequately implemented in many developing countries. This paper investigates
industry stakeholders’ awareness of the current state of, factors driving, and barriers hindering
the adoption of sustainable construction (SC) in Cambodia. Using an empirical questionnaire
survey targeting local construction professionals, respondents were invited to rate their level of
awareness, knowledge and understanding of SC, as well as to rate the level of importance of 31 drivers
and 10 barriers identified from the seminal literature. The data set was subjected to the relative
importance index method. The results suggest that the industry-wide adoption of SC practices
is poor, which is believed to be due to a lack of awareness and knowledge, and reluctance to
adopt new sustainable technologies. Furthermore, more efforts must be put into the selection of
more durable materials for the extension of buildings’ lives and to minimize material consumption,
as well as to develop energy-efficient buildings with minimal environmental impact and a healthy
indoor environment, so that the ability of future generations to meet their own needs will not be
compromised. The outcomes of this study have enriched knowledge about the current state of,
drivers of, and barriers to sustainable construction in a typical developing economy. Although the
outcomes of this study were a short scoping exercise, it has formed a significant base for future SC
work within Cambodia
Castes and classes in the environment of media from the communication discourses point of view
No full textThe paper deals with the questions of bodyness when new castes and classes form in a mediated environment.
The theses is developed as follows. (1) The media contribute to the formation of new castes, the
attributes of which are corporeal styles. (2) The society fragmentizes when its members group into one or
another class despite the tendencies of the unifying media. The author analyses the contradictory tendencies
of contemporary society. The life art of the consumers become similar in global way but because of
an exclusive consuming, the rich caste forms as well. According to the author, the new post-revolutionary
(in both senses) social order narrowed the perspective instead of opening it. The relationship between
bodyness and castes and corporeal style as a feature of new caste are analyzed from the perspectives of
different communication schools. In addition to that, the question about metacommunication as communicative
practice is discusse
An influence of the correlation due tracking the same satellite on the accuracy of the GPS time dissemination
No full textWe do analyse the influence of the correlation on time signals received from the same satellite using commonview technique on the accuracy of GPS time dissemination during time synchronization by quantum oscillators.
We focus on the case when the interval between instances in time is much shorter than a second, and the PPS
(Pulse per Second) technique is applicable. Next, estimates were made on the influence of the atmosphere,
ionosphere conditions and the Doppler effect on the dissemination of time signals. It has been found, that the
standard deviation of the time interval between two moments in time is about 35 ns, when the time signals are
transmitted for thousands of kilometers due to influence of the atmosphere, the ionosphere and the Doppler
effect. That gives the ratio of the time intervals measurements equal to approximately 5 · 10−
Risk and damage assessment for transportation of dangerous freight
No full textThe article provides information on transportation of dangerous freight. Legal acts regulating transportation of Dangerous
freight are discussed. Major problems and non-compliances with The European Agreement concerning International Carriage of
Dangerous Goods by Road (ADR) are distinguished. The type of risk that one encounters is analysed, as well as who is to take
responsibility for transportation of dangerous freight. Transport accidents of dangerous substances are increasingly frequent and can
cause serious injuries in inhabited areas or pollution of the environment. For quantitative risk assessment and mitigation planning,
consequence calculations are necessary. The aim of this article is to present methods of the first approach for calculating costs and
overall expenses of an accident and to demonstrate the main recommendations for the next development stage in the area of
transport accident modelling. By the means of risk assessment models, it is possible to calculate the extent of the consequences and
reduce the risks during the process of transportation. Based on Technology of Dangerous Freight Transportation, the accident
calculation principles are suggested, which enables to assess the costs and to find a generalized accident rate. The calculation results
are provided
Metai ir dienos. VGTU 2017 m.
Get PDFLeidinyje aprašomi VGTU 2017 metų svarbiausieji įvykiai, mokslo ir studijų plėtotė, tarptautinis bendradarbiavimas, dalyvavimas tarptautinėse konferencijose, senato ir rektorato priimti sprendimai ir kt. Taip pat pateikiama žinių apie universiteto padalinius: fakultetus, katedras, centrus, institutus ir kt.
Leidinys skirtas plačiajai visuomenei
Toward efficient policy making: forecasts of vulnerability to external global threats
No full textEach country has to be able to develop efficient economic policy, facilitating sustainable economic development
of national economy. In order to devise such policy, development patterns of a country has to be known, external threats
indicated and various scenarios of their impact has to be foreseen, their impact forecasted and discussed. Alas, in contemporary
environment in conditions of globalization predicting of development peculiarities and external factors’ impact
becomes especially urgent issue. Presented paper is devoted to discussion about predicted development selected national
economies with account of threats caused by global environment. Economic indicators of Lithuania and Germany forested
for period of three years, estimated, are being analyzed. The following methodology is applied. At first main macroeconomic
indicators, such as real GDP growth, inflation, interest rates and unemployment ceteris paribus forecasted until year
2022 will be compared. The second, external threats will be selected and considered. Forecasted impact of indicated threats
on real GDP growth of Lithuania and Germany will be discussed; source of employed data: database Passport, provided by
Euromonitor International Company and powered by Clarivate Analytics (data are provided for research purposes for subscribed
users). Change of real GDP growth in Lithuania and Germany under indicated threats pressure after one year period
and three years period is juxtaposed. The findings suggest insights about development patterns of small comparatively less
developed open economy and big well developed country belonging to the same economic union. Findings are instrumental
for devising national economic policies enhancing resilience of national economies to external (global) threats
Identification analysis of digital images of black holes of Centaurus A galaxy
No full textThis article analyses digital images from the black hole map of Centaurus A galaxy using autovariance and covariance functions. This map was created based on data collected with APEX and Max-Planck/ESO radiotelescopes in Chile (Nemiroff and Bonnell in Astronomy picture of the day, 2011. https://apod.nasa.gov/apod/ap110531.html). Crosscovariance function estimates for two digital images or autocovariance function for individual images are calculated with random functions based on digital images’ pixels in vector form. Pixel vectors are estimated by emitting arrays of digital images’ pixels along according vectors. When the scale of the digital image shifts, the frequency of individual pixels’ colors remains constant, therefore shifting scales do not affect calculations for const and covariance functions. An RGB color spectrum was used for identification of images. The effect of composites of the RGB spectrum, and of color tensors, on estimates of covariance functions in digital images was assessed as well. The identity of digital images is evaluated by the change of correlation coefficients in the diapason of according values as determined using Matlab software