Disertacija yra skirta relaksacijos procesų, vykstančių optoelektronikos medžiagose ir prietaisuose, tyrimui dažninės skyros metodu. Įprastas fluorescencijos gesimo trukmės tyrimo metodas, veikiantis harmoniškai moduliuoto žadinimo režimu, buvo adaptuotas žadinimui puslaidininkiniais šviestukais ir signalų registravimui radijo dažnių faziniu detektoriumi. Neorganiniai vandeniniu zolių-gelių metodu susintetinti fosforai, skirti baltų puslaidininkinių šviestukų gamybai, ir modernios organinės optoelektronikos medžiagos buvo ištirtos fotoliuminescencijos gesimo dėsnio ir kvantinės išeigos matavimo metodikomis, siekiant nustatyti krūvininkų rekombinacijos savybes ir optimizuoti sintezės parametrus. Realizuotas GaN epitaksinių sluoksnių liuminescencijos kinetikos tyrimas labai žemo kvazitolydinio sužadinimo atveju patvirtino rekombinacijos per priemaišas svarbą šio tipo medžiagose. Buvo sukurtos naujos prekinių šviestukų šiluminių savybių in-situ tyrimo metodikos, veikiančios dažninės skyros režimu. Bangos ilgio keitiklių temperatūra baltuose šviestukuose ir šilumos relaksacijos konstantos įvairaus tipo šviestukų konstrukciniuose elementuose buvo išmatuotos esant vardiniam šviestukų veikimo režimui. / The thesis is devoted to the frequency-resolved investigation of the relaxation processes in optoelectronic materials and devices. Conventional fluorescence decay time measurement technique in the frequency domain was adapted for the use with light-emitting diode (LED) excitation and signal registration by a lock-in amplifier. Inorganic phosphors synthesized by aqueous sol-gel combustion method for using as wavelength converters in white LEDs as well as advanced organic semiconducting materials were investigated by photoluminescence decay time and quantum yield measurement techniques. The photoluminescence decay time measurement technique with extremely low quasi-continuous UV LED excitation was applied for the carrier dynamics research in GaN epitaxial layers. The investigation under such a low excitation conditions revealed the contribution of donor-acceptor recombination in the yellow luminescence of GaN. The techniques for in-situ thermal characterization of encapsulated LEDs, including the measurements of phosphors converter temperature and heat relaxation time constants inside a LED, were developed and demonstrated for the investigation of commercial low- and high- power LEDs.

The main aim of this thesis paper is to determine the influence of physical and mechanical indices of asphalt concrete pavement on the operational properties of Lithuanian highway pavement as well as on the functional lifetime of road pavement. The analysis of pavement condition of Lithuanian highways is presented. The classification regarding the damage and deformation of material used for the construction of asphalt concrete pavement and of road pavement structure is provided. The causes of the afore-mentioned damages and deformations are also explained and rectification methods which can be applied to eliminate these causes are described. The operational conditions of the road pavement and its structure as well as the applicable methods are theoretically justified. In addition, the physical and mechanical indices of asphalt concrete pavement of the highway Vilnius – Kaunas - Klaipėda (A1) and of pavement roughness in accordance with IRI research data are given. The analysis of the data allowed the correlation between the two items to be determined. The research material was processed by means of the statistical software package “Statgraphics 5.1 Plius”. Standardized physical and mechanical indices of asphalt concrete pavement which affect the functional lifetime of pavement structure are presented. The conclusions and recommendations are provided.

The aim of the study: to compare the conditions and growth properties of naturally regenerated and planted Scots pine stands, and to evaluate the impact of Scots pine plantations on chemical parameters of Arenosols. The object of the study: the naturally regenerated and planted Scots pine stands of different age in Varėna Forest Enterprise Merkis forest district and in the experiment of Perloja Experimental Station of Lithuanian Institute of Agriculture. The research methods: the analyses of Forest Survey data, technical measurements, the chemical analyses of Arenosols samples: pH, the capability of nutrients (N, P, K, Ca, Mg) and organic carbon. The research results: the conditions and growth properties of naturally regenerated and planted Scots pine stands in Perloja experiment and in neighbour stands; the changes of chemical properties of Arenosols (pH, the capability of nutrients and organic carbon) afforested by Scots pine were estimated.

Introduction. At low temperature the preservation of foodstuffs is one of the best ways of their storage and therefore this method is widely used in meat industry. The low temperature suppresses the activity of microorganisms and tissue ferments. Therefore the meat preserved by freezing keeps for a long time its initial properties and there are only minimal changes of food value and taste. At low temperature the activity of ferments slows down but does not stop. Work object. The work object is the determination of the change of physical-chemical properties of meat during freezing and keeping in - 180 C and - 860 C temperature. Work methodics. The research as fulfilled at the laboratory of the evaluation of the cattle meat properties and the meat quality. For the rersearch taken 14 Lithuanian white pig meat samples the mean weight of which was 500 g. were taken. They were put into special freezing bags and were frozen at temperature -180 C, and -860 C. Before freezing it the physical-chemical properties of the meat were determined. Two examples from each meat samples were researched. The determination of the physical-chemical properties of the meat was fulfilled every month. Also were was taken 6 Lithuanian white pig meat samples the mean weight of which was 500 g. Before freezing it the physical-chemical properties of the meat were determined. After that was made green tea extract, 500 ml. Water ant 50 g tea. All extract was inject in to the meat samples. They were put... [to full text]

The Results of Survey. During the acclimatization process fatten features of C and D lines pigs offspring are changing to the right side. But differences are not statistically trusted. During the acclimatization process fleshy features of C and D lines pigs’ offspring practically did not change. Trusted difference in D line estimated only to carcass side length (cm), which declined 3.9 cm (p<0.001), or in C line to carcass side length (p<0.005), which shorten pro rata 5.2 cm and 3.63 cm comparing with imported pigs offspring results. Trusted differences are not estimated to the remainder rates of fleshy features. That fleshy features did not change during the acclimatization process is seen from phenotipical estimation results. Fat thickness of C line pigs pedigree get – at 1 point rise 1.84 mm (p<0.005), or fat thickness of D line pedigree get – at 1 point even decrease 0.57 mm (p<0.005), comparing with imported pedigree get. During acclimatization process reproductive features C and D line sow practically did not change, only milkyness and percentage of piglets preservation from generation to generations improved. C line sow milkyness increased 10.68 kg (p<0.005), or D line sow 13.01 kg (p<0.001). Percentage of piglets preservation increased 7 % (p<0.025) in C line and 5.69 % (p<0.050) in D line. During acclimatization process time from piglet weaning till the first insemination is shorten 1.02 and 2.14 day (p<0.025) pro rata in C line F1 and F2 generations. But this time... [to full text]

Stiffnes of leg's receiver and skin and soft tissues at contact place are researched in the master thesis. Using the finite elements method with digital ANSYS programmable packet was made non-linear model of leg's prothesis receiver and stump of soft tissues . Made calculiation have shown that deformation ratio in stump and receiver contact declines when the lood increases. Therefore it is very important to evaluate not only the height of desabled persion but also his weight durind estimation the magnitude of deviations of leg prosthesis manufacturing and assembly.

Šiame baigiamajame magistro darbe nagrinėjama polistireninio putplasčio stiprumo savybės. Teorinėje dalyje pateikta literatūros analizė, bendros žinios apie polistireninį putplastį, gamybos būdai, panaudojimo galimybės. Išnagrinėta trijų didžiausių gamintojų Lietuvoje siūloma produkcija. Apžvelgti reikalavimai pastatų atitvarų šiluminei varžai, išnagrinėta termoizoliacinio sluoksnio storio pokytis nuo TSRS laikų iki dabar. Eksperimentinėje dalyje aprašomos naudotos medžiagos; jų charakteristikos; gniuždomasis stipris; šliejamasis stipris; išnagrinėta skirtingo tankio bandinių mikrostruktūra ir makrostruktūra. Aprašomi rezultatai, naudojant statistinės analizės programą atliekama jų analizė, suformuluojamos išvados. / The present work of Master degree studies analyzes the properties of expanded polystyrene.Theoretical par of this work introduces analysis of references, general information on expanded polystyrene, manner of production and fields of application. The work analyzes production offered by three biggest manufacturers in Lithuania, reviews the requirements applicable to thermal resistance of enclosures of the building, analyses alteration of thickness of a heat insulation layer comparing the situation in Soviet Union time and nowadays. Experimental part describes the used material, their properties, compressive strength, shear strength; analyses microstructure and macrostructure of samples of different density. The work presents the results and analysis of the results by applying software of statistical analysis; formulation of conclusions.

Disertacijoje aprašoma prūsų kalbos kirčiavimo sistema, galimà atsekti iš šaltinių (visų pirma III prūsų kalbos katekizmo, teikiančio daugiausia akcentologijos duomenų) rašybos. Siekiama atkurti kiek įmanoma išsamesnį sinchroninį sistemos vaizdą ir nustatyti galimas diachronines jos raidos tendencijas. Kritiškai įvertinus visas iki šiol paskelbtas prūsų kalbos akcentologijos ir akcentografijos teorijas, pirmajame tyrimo etape apibrėžiami kirčiuoto skiemens nustatymo iš šaltinių rašybos principai, įvertinamas tokių mokslinėje literatūroje prūsų kalbai postuluojamų reiškinių kaip Saussure'o-Fortunatovo ar Kortlandto dėsniai realumas. Kirčiavimo sistemos analizėje, laikantis morfologinės akcentologijos principų, nustatomos kirčiavimą lemiančios paliudytų prūsų kalbos žodžių morfemų akcentinės savybės, žodžiai klasifikuojami į akcentines paradigmas, analizuojamas kirčio vaidmuo žodžių daryboje. Sinchroniniais metodais atkurta sistema nuosekliai lyginama su giminiškų kalbų (visų pirma lietuvių ir slavų) kirčiavimo sistemomis, konstatuojami jų sutapimai ir motyvuojami skirtumai. / The dissertation contains a description of the accentual system of Old Prussian as evidenced by the orthography of Prussian written monuments, particularly that of the Third Catechism (which abounds the most in accentological data). An attempt is made to reconstruct, as comprehensively as possible, the synchronic state of the accentual system in question, as well as to identify any possible trends in its diachronic development. At the first stage of research, upon a critical examination of all the theories dealing with Old Prussian accentology and accentography published to date, the methods of identifying the stressed syllable based on the orthography of the written monuments are outlined. The validity of Saussure-Fortunatov’s and Kortlandt’s laws, which have been postulated in the scholarly literature on Old Prussian, is subjected to a re-evaluation. Then, an analysis of the accentual system is undertaken, in adherence to the principles of morphological accentology, in order to determine the accentual properties of the Old Prussian morphemes conditioning the stress of the attested words, as well as to classify the words by accentual paradigm and to elucidate the role of stress in word-formation. This reconstructed synchronic system is then thoroughly confronted with those of the related languages (primarily Lithuanian and Slavic) to demonstrate the correspondences and to account for the discrepancies between them.

Bakalauro baigiamajame darbe atliekamas vadovo bendravimo su pavaldiniais vertinimas paslaugų sektoriuose (Šiaulių miesto valyklose, viešbučiuose, Šiaulių ir Norvegijos skalbyklose). Klausimynas, pagal kurį atlikta darbuotojų apklausa tiriamų paslaugų sektorių įmonėse, parengtas remianti vadybinės literatūros autorių (Jasinavičius, Sokol, 2005; Kasiulis, Barvydienė, 2005; Baršauskienė, Janulevičiūtė, 1999) išskirtomis asmeninėmis vadovo savybėmis, originaliu Costigan ir Schmeidler sudarytu bendravimo klimato (CCI) klausimynu bei lietuvių autorių (Bakanauskienė, Petkevičiūtė, 2003; Misevičius, Urbonienė, 2006) išskirtais bendravimo trukdžiais. Apklausoje dalyvavo 181 respondentų (63 – viešbučių darbuotojų, 65 – valyklos, 26 – Šiaulių skalbyklos, 27 – Norvegijos skalbyklos). Tyrimo metu nustatyta, kad visuose paslaugų sektoriuose išryškėjo trys darbuotojams imponuojančios vadovo asmeninės savybės: santykių šiltumas, nuoširdumas, empatija. Tiriamose paslaugų sferose dominuoja palaikantis bendravimo klimatas, tačiau yra ir gynybinio bendravimo klimato apraiškų. Palaikantį bendravimo klimatą labiausiai stiprina tokie veiksniai kaip „problemų įvardinimas darbuotojams“, „vadovo pagarbus elgesys su pavaldiniais“ ir „vadovo aiškus ir objektyvus situacijos apibūdinimas“. Tuo tarpu gynybinio bendravimo klimato raišką labiausiai stiprina „vadovo asmeninės pozicijos pabrėžimas“ ir per didelis „vadovo asmeninės atsakomybės prisiėmimas už darbo rezultatus“. Tiriamuose paslaugų sektoriuose... [toliau žr. visą tekstą] / The aim of the paper is to compare supervisor - employee communication patterns in a different type of service providing organizations (laundries, hotels in Šiauliai, Šiauliai washhouse, Norway washhouse). Framework of this study is the personal supervisor characteristics, offered by managerial literature authors (Jasinavičius, Sokol, 2005; Kasiulis, Barvydienė, 2005; Baršauskienė, Janulevičiūtė, 1999) original communication climate inventory (CCI) operationalized by J. I. Costigan and M. A. Schmeidler (1984) and communication barriers, offered by lithuanian authors (Bakanauskienė, Petkevičiūtė, 2003; Misevičius, Urbonienė, 2006). There were 181 respondents involved in this survey (63 - employees from Šiauliai hotels, 65 - employees from Šiauliai laundries, 26 - employees from Šiauliai washhouse, 27 - employees from Norway washhouse). The final results of the survey were grouped and interpreted as well as conclusions made. While carrying out the survey it was found out that sincerity, empathy, warm relationships are the most important personal supervisor characteristics. The results showed that supportive communication climate dominates in all service sectors, but there are some manifestations of the defensive communication climates as well. The most important factors of the supportive climate dominance in the organizations are that supervisors define clearly problems, treat with their employees with respect and characterize situation clearly and objective. The most important... [to full text]

Saviformuojantys puslaidininkiniai kvantiniai taškai (quantum dots, QDs), kurių charakteringos elektronų subjuostinių (intraband) šuolių energijos yra infraraudonajame spektriniame ruože (3–25 μm), sudaro daugelio fotojutiklių aktyviąją terpę ir yra aktualūs taikymams šiuolaikinėje optoelektronikoje. Disertacijoje nagrinėjami molekulinio pluoštelio epitaksijos būdu užauginti: -- InAs kvantiniai taškai, įterpti į GaAs matricą ir GaAs/AlAs supergardelę; -- InAs kvantiniai taškai be ir su įtempimus sumažinančiuoju InGaAs sluoksniu, įterpti į kompozitinę GaAs/AlAs kvantinę duobę; -- skirtingo aukščio koloniniai InGaAs kvantiniai taškai arba kvantiniai strypeliai (quantum rods, QRs), apsupti dvimačiu InGaAs sluoksniu, ir užauginti naudojant arba As2, arba As4 šaltinį. Taikant moduliacinę atspindžio spektroskopiją ir fotoliuminescenciją, buvo ištirtos šių darinių optinės savybės bei jų elektroninė sandara, o taip pat atskleista auginimo sąlygų įtaka darinių struktūrai. Eksperimentiniai tyrimai buvo interpretuojami atliekant teorinį modeliavimą skaitmeniniu (nextnano3 programa) bei analitiniu (sukurtas algoritmas) metodais. / Self-assembled InAs quantum dots (QDs), whose intersublevel transition energies lie in the mid- and far-infrared spectral range (3–25μm), have attracted particular interest as active elements of infrared photodetectors. This interest is mainly due to intriguing atomic-like quantum confinement and unique optical and electronic properties of QDs. Moreover, QD electronic structure can be adjusted by varying the dots size and shape or their environment. These features make QDs to be of importance in creation of photoelectronic devices with a desired spectral range. The dissertation is concerned specifically with molecular beam epitaxy grown InGaAs QD structures with: -- InAs QD stacks embedded in GaAs matrix and GaAs/AlAs superlattice (SL), or alternatively InAs/GaAs QD-SL structures with and without AlAs barriers between the dot layers; -- InAs QDs with and without InGaAs strain-reducing layers, embedded within GaAs/AlAs quantum wells; -- columnar InGaAs QDs, also referred to as quantum rods (QRs) or quantum posts, of different morphology. (The quantum confined structure consists of vertically oriented InGaAs QRs immersed in a two-dimensional InGaAs layer). These QD structures were studied by modulated reflectance and photo- luminescence spectroscopies to reveal their optical properties and the full- extent of electronic structure. Experimental data were interpreted by numerical (nextnano3 software) and analytical (algorithm developed) modelling.