The object of the thesis was to develop a simple method of the ADC quality evaluation of computer audio systems, which does not require a special apparatus, and software for its realization. To correct the ADC ENOB measurement methodology recommended in the IEEE Std 1241-2000. By applying the recommended method, to investigate possibilities of formation and application of new test analog signals for ADC investigation. To show the possibilities of untraditional computer audio systems application for measurements.

The graduating paper focuses on the digital image capture method in criminalistic and also on its legal regulation and practical resort in the law enforcement institutions‘ investigations of criminal acts. The digital image capture is one of the methods of digital image capture in criminalistic. Its structure contains digital photography and digital video recording. The digital photography is used for strategical and investigative photography. The usage of the digital image capture method investigating the criminal acts is not against the provision of the Criminal Procedure Code. This method is not regulated by any other legal instrument. It often happens that the media captured by the digital camera under investigation is not attached to the criminal case. It is the violation of the Criminal Procedure Code. The digital photography is used in the pretrial investigation institutions‘ work but the traditional photography is used as well. There are no anticipated procedures how to protect the digital photography and files from the substitution, forgery and erasure. The digital information can be protected by establishing the procedures of the standard operations. One of the ways to protect it is electronic signature.

The dissertation investigates the issues of image authentication and tamper localization after general image processing operations – blurring, sharpening, rotation and JPEG compression. The dissertation consists of four parts including Introduction, 4 chapters, Conclusions, References. The introduction reveals the investigated problem, importance of the thesis and the object of research and describes the purpose and tasks of the paper, research methodology, scientific novelty, the practical significance of results examined in the paper and defended statements. The introduction ends in presenting the author’s publications on the subject of the defended dissertation, offering the material of made presentations in conferences and defining the structure of the dissertation. Chapter 1 revises used literature, analyzes competitive methods. The devastating effect of blur/sharpen methods on digital image matrices is shown. General pixel-wise tamper localization methods are completely inefficient after such casual processing. Block-wise methods demonstrate some resistance against blurring/sharpening, but no tamper localization with the resolution of up to one pixel is possible. There is clearly a need for a method, able to locate damaged pixels despite general image processing operations such as blurring or sharpening. Chapter 2 defines theoretical foundation for the proposed method. It is shown that phase of Fourier transform demonstrates invariance against blurring or sharpening... [to full text] / Disertacijoje nagrinėjamos atvaizdų apsaugos – autentiškumo užtikrinimo ir pažeidimų radimo, po bendrųjų vaizdo apdorojimo procedūrų – blukinimo, ryškinimo, pasukimo ar JPEG suspaudimo – problemos. Disertaciją sudaro įvadas, keturi skyriai, rezultatų apibendrinimas, 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 pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmasis skyrius skirtas literatūros apžvalgai. Jame pateikta konkuruojančių metodų apžvalga. Parodomas globalus blukinimo/ryškinimo operacijų poveikis atvaizdo skaitmeninėms matricoms. Išsiaiškinama kodėl pikselių tikslumo metodai nėra atsparūs tokiam poveikiui. Kodėl blokiniai metodai demonstruoja dalinį atsparumą – bet jie nėra pajėgūs surasti vieno pažeisto pikselio. Parodomas aiškus poreikis metodo, tiek galinčio rasti pažeistus pikselius, tiek atsparaus bendroms vaizdo apdorojimo procedūroms, tokioms kaip blukinimas ar aštrinimas. Antrajame skyriuje pateiktas sukurto metodo teorinis pagrindimas. Įrodoma, kad Furjė fazė pasižymi atsparumu blukinimui ir ryškinimui. Tačiau iškyla sekanti problema dėl to, kad Furjė fazėje neįmanoma rasti konkretaus pikselio –... [toliau žr. visą tekstą]

Darbe nagrinėjama atributinės informacijos sertifikavimo šiuo metu naudojamuose elektroniniuse parašuose problema. Trumpai apžvelgiami elektroninio parašo principai ir supažindinama su viešųjų raktų infrastruktūra, nurodant galimybes jai išplėsti, iškilus poreikiui užtikrinti aukštesnį saugumo lygį keičiantis papildoma (atributine) informacija. Nagrinėjami įvairūs atributinės informacijos sertifikavimo metodai, viešųjų raktų infrastruktūroje įvedant atributų sertifikato ir atributų sertifikavimo centro sąvokas. Pateikiamas tinkamiausio metodo pritaikymo pavyzdys, modeliuojant elektroninio parašo naudojimo situaciją, artimą dabartinei situacijai Lietuvoje. Sprendimo pritaikymas demonstruojamas apibrėžiant patobulintos elektroninio parašo infrastruktūros prototipą. / This paper analyses issues of attribute certification in currently used electronic signatures. Fundamentals of electronic signatures and public key infrastructure are briefly described, focusing on possibilities of achieving higher security level in communication when attribute information is important. Various suggestions for attribute certification are analysed, introducing atribute certificates and atribute authorities. Different certification methods are compared and evaluated, applying the most suitable one in the public key infrastructure usage model, that is constructed by simplifying the current situation of electronic signatures. The solution is represented by describing the prototype of improved electronic signature infrastructure.

The final master‘s work analyzes problems which occur or may occur due to taking the land for public needs when implementing the program of asphalt works on gravel roads in the area of activity of state enterprise „Telšių regiono keliai“. A research of sections of gravel roads intended for reconstruction and included into the program of maintenance and expansion of public highways for 2002–2015 was carried out, in the course of which a road plan was projected following norms of road engineering and the extent of taking the land for public needs was evaluated. Recommendations regarding the expedience of taking the land for road lane when implementing the program of asphalt works on gravel roads in the area of activity of state enterprise „Telšių regiono keliai“ were rendered.