Tolerisanje grešaka i energetska efikasnost kod sistema za rad u realnom vremenu sa vremenskom redundansom

The concept of real-time systems (RTSs) is presented in the computer science for decades. During that period, the RTSs have evolved from special purpose microcomputer systems for industrial application to various forms of embedded system that are deeply ingrained in wide segments of daily life. The new application domains pose new design requirements and goals to RTSs, which are now often required to provide both fault tolerance and energy efficiency in addition to their main objective to compute and deliver correct results within a specified period of time. There is a fundamental tradeoff between these two additional requirements because fault tolerance techniques use slack time to improve reliability while low energy consumption techniques exploits slack time to increase energy efficiency. The central problem considered in the dissertation is how to optimally distribute the slack time between these techniques. Dynamic voltage scaling (DVS) is known as one of the most effective low-energy technique for RTSs. However, most existing DVS techniques only focus on minimizing energy consumption without taking the fault-tolerant capability of RTSs into account. In order to solve specify problem in this dissertation, a new heuristic-based fault-tolerant dynamic voltage and frequency scaling (FT-DVFS) algorithm is developed. The goal of the proposed algorithm is to minimize the amount of energy consumed by a real-time system under fault tolerance constraints while guaranteeing that all real-time tasks can complete successfully before their deadlines. Basically, the FT-DVFS is a DVS algorithm with integrated response time analysis (RTA) to check both the schedulability and the fault tolerant constraints of real-time task sets. The performances of FT-DVFS algorithm are evaluated by simulation in a custom build simulator. The simulation results are analyzed from three different points of view: the schedulability, the energy consumption, and the fault tolerance. The simulation results show that the proposed algorithm saves a significant amount of energy even with only two frequency/voltage levels, and the savings further increases with the increase of the number of frequency levels. Also, the simulations show that the reduction in power consumption, which can be achieved with FT-DVFS algorithm decreases with the increase of the processor utilization factor (i.e. processor spare time). The simulation results from the fault tolerant point of view show that the higher level of fault tolerance can only be attained through sacrificing a part of savings in power consumption, and vice versa. The proposed heuristic FT-DVFS algorithm is compared with the optimal DVS algorithm. The simulation analysis show that FT-DVFS algorithm achieves near-optimal solutions in very short computation time even for large task sets

Bio-inspired control of redundant robotic systems: Optimization approach

Osnovni cilj ovog rada je da promoviše pristup biološki inspirisanog sinergijskog upravljanja koji omogućava da se razreši redundansa datog robotizovanog sistema koji se može koristiti i za vojne svrhe. Pokazano je da je moguće razrešiti kinematički redundansu primenom metode lokalne optimizacije i bioloških analogona - sinergijsko upravljački pristup sa uvođenjem logičkog upravljanja i distribuiranog pozicioniranja. Takođe, mogućnost prebacivanja između sinegrija u okviru jedne trajektorije je razmatrano. Na kraju, problem aktuatorske redundanse je postavljen i rešen primenom Pontrjaginovog principa maksimuma. Upravljačka sinergija je ustanovljena primenom postupka optimizacije na koordinacionom nivou. Na kraju, efikasnost predložene biološki inspirisane optimalne upravljačke sinergije je demonstriran na pogodno usvojenom robotskom sistemu sa tri stepena slobode i četiri upravljačke promenljive, kao ilustrativnog primera.The major aim of this paper is to promote a biologically inspired control synergy approach that allows the resolution of redundancy of a given robotized system which can be used for military purposes. It is shown that it is possible to resolve kinematic redundancy using the local optimization method and biological analogues - control synergy approach, introducing hypothetical control and distributed positioning. Also, the possibility of switching synergies within a single trajectory is treated, where the control synergy approach applying logical control is used. The actuator redundancy control problem has been stated and solved using Pontryagin's maximum principle. Control synergy as a class of dynamic synergy is established by the optimization law at the coordination level. Finally, the effectiveness of the suggested biologically inspired optimal control synergy is demonstrated with a suitable robot with three degrees of freedom and four control variables, as an illustrative example.

Mehanika robota

Udžbenik Mehanika robota napisan je prema programu istoimenog predmeta na Mašinskom fakultetu u Beogradu i namenjen je studentima Mašinskog fakulteta, ali može biti koristan i studentima drugih fakulteta čiji nastavni plan obuhvata program mehanike robotskih sistema i dinamike sistema krutih tela. Godinama unazad predmet Mehanika robota bio je predavan na Mašinskom fakultetu na smerovima Automatsko upravljanje i Industrijsko inženjerstvo (integrisani program studija do 2005) a kasnije u okviru novog sistema studija kao izborni predmet na master studijama (moduli Automatsko upravljanje i Biomedicinsko inženjerstvo). Glavni rezultati ove knjige izloženi su matematičkim formalizmom koji je u velikoj meri uskladjen sa softverskim mogućnostima savremenih računara i koji dopušta jednostavno formiranje odgovarajućih kompjuterskih programa. Pri tome teorijsko izlaganje koje je prezentovano u ovom udžbeniku je je potvrdjeno i brojnim primerima koji su prezentovani posebno u Zbirci zadataka iz mehanike robota (drugi autor ove knjige). U ovoj knjizi je pokazano da se sve poznate metode svode na problem formiranja metričkog tenzora sistema tela i određivanje generalisanih sila sistema sila koje deluju na robotski sistem. Sa te tačke gledišta, sve metode za formiranje diferencijalnih jednačina kretanja sistema tela potpuno su ravnopravne. Knjiga je prezentovana čitaocima sa nadom da je dovoljno rigorozno napisana i pri tome dovoljno jednostavno da studente uveri da i tako komplikovana materija, poput one koju sačinjava Analitička mehanika, može da se prepusti programerima čiji će programi zahtevati da njihov korisnik poznaje u opštim crtama glavne rezultate knjige a da mu se pri tome otvara mogućnost za svestranu dinamičku analizu tehničkih objekata.drugo izdanj

Resolution of redundancy using local optimization: A synergy approach

Glavni cilj ovog rada je da promoviše sinergijski pristup koji omogućuje upravljanje redundantnim robotskim mehanizmom. Pokazano je da novo robotsko upravljanje se može ostvariti primenom odgovarajućeg biološkog analogona uvođenjem hipotetičkog upravljanja uz primenu prethodno navedenog sinergijskog pristupa, tako da je moguće razrešiti kinematičku redundansu. Takođe, u ovom radu je razmatrana i mogućnost uključivanja - prebacivanja sinergija u okviru jednog pokreta a prema zahtevima zadatka, što je realizovano korišćenjem logičkog upravljanja sa aspekta sinergijskog upravljanja.The major aim of this study is to promote a synergy approach which allows controlling redundant robotic mechanism. It will be shown that new robot control can be established using an appropriate biological analog where introducing the hypothetical control and applying the synergy approach it will be possible to resolve the kinematics redundancy. Also, in this paper the possibility of switching synergies within a single movement according to the task requirements is treated and the synergy approach with the logical controls proposed to solve this problem

Model-driven development of Data Vault based data warehouses.

U tezi je razmatrano više problema vezanih za projektovanje i razvoj skladišta podataka, kao što su: - neusaglašenost skladišta podataka sa izvorima podataka, nastala kao rezultat permanentnih promena strukture izvora, - nekompletnost podataka u skladištu podataka, - heterogenost modela izvora i njihova semantička neusaglašenost - nepostojanje standardnog konceptualnog modela i modela strukture skladišta podataka...Several issues, related to the design and development of data warehouses, are analyzed in this thesis: - inconsistency between the data warehouse and data sources due to the permanent changes in the structure of the data sources, - incompleteness of the stored data, - heterogeneity of data source models and their semantic inconsistency, - absence of standardized conceptual or structural data warehouse models..

Primena digitalne grafičke baze podataka u prostornom planiranju

The application of a digital graphic data base in town and country planning // Contemporary level of development and indicated directions of the development of informational technology are contributing to the establishing of an integrated approach to physical planning. However, the methodological approach to designation of physical / spatial plan imposes a specific requirements to informational technology, while the development of informational technology is evolving towards a varied modes of application, the intention is to bring closer and to adopt this domains through the gradual standardisation of the modes of presenting the information on space territory and through compatibility of terminology of planning and computerised approaches and tectonics. The papers deals with the possibilities of achieving that, and the basis for it is the digital graphic's data base with an integrated graphic, textual and numeric data into an unified relational system, The starting point is well founded, organised and integrated overall informational basis of physical / spatial plan, what presents the best support for an integrated approach to planning, organisation, the modes of uses and protection of the territory / space.Urednik: Dimitrije PerišićPosebna izdanja IAUS br.2

Dekodovanje kodova sa malom gustinom provera parnosti u prisustvu grešaka u logičkim kolima

Sve ve´ca integracija poluprovodniˇckih tehnologija, varijacije nastale usled nesavršenosti procesa proizvodnje, kao zahtevi za smanjenjem napona napajanja cˇine elektronske ured¯aje inherentno nepouzdanim. Agresivno skaliranje napona smanjuje otpornost na šum i dovodi do nepouzdanog rada ured¯aja. Široko je prihvac´ena paradigma prema kojoj se naredne generacije digitalnih elektronskih ured¯aja moraju opremiti logikom za korekciju hardverskih grešaka...Due to huge density integration increase, lower supply voltages, and variations in technological process, complementary metal-oxide-semiconductor (CMOS) and emerging nanoelectronic devices are inherently unreliable. Moreover, the demands for energy efficiency require reduction of energy consumption by several orders of magnitude, which can be done only by aggressive supply voltage scaling. Consequently, the signal levels are much lower and closer to the noise level, which reduces the component noise immunity and leads to unreliable behavior. It is widely accepted that future generations of circuits and systems must be designed to deal with unreliable components..

Developing listening comprenhension in the context of audio and video input ; Развитие умений понимания речи в контексте видео и аудио входных материалов

Danas je opšte prihvaćeno da veština razumevanja govora igra ključnu ulogu u učenju stranog jezika. Ona podrazumeva istovremeno odvijanje niza aktivnih procesa, koji su pod kontrolom slušaoca, kao i pasivnih, koji nisu. Svi oni omogućuju slušaocu da interpretira govor u realnom vremenu oslanjajući se na različite vrste znanja: lingvistička i nelingvistička. Imajući u vidu složenost ovih procesa, jasno je zašto se razumevanje govora smatra veštinom kojom je najteže ovladati u učenju stranog jezika...Today it is generally accepted that listening comprehension plays a key role in learning a foreign language. It implies a simultaneous activation of a series of processes, the active ones, which can be controlled by the listener, as well as the passive ones, which cannot. They enable the listener to interpret speech in real time by relying on different kinds of knowledge: linguistic and non-linguistic. Given the complexity of these processes, it is obvious why listening comprehension is considered to be the most difficult skill to master in a foreign language..

Soft-decision decoding of MTR codes over magnetic recording channels

U radu su predstavljene nove tehnike dekodovanja maximum transition run (MTR) kodova na principu finog odlučivanja. Analizirane su performanse ovih tehnika u kombinaciji sa zaštitnim LDPC kodom na kanalima za magnetsko memorisanje informacija, sa posebnim osvrtom na model kanala sa dve staze za zapisivanje i dve glave za čitanje. U modelu kanala je korišćena idealna E2PR4 ekvalizacija staza adekvatna za sisteme sa visokom gustinom magnetskog zapisa.This thesis presents the novel soft-decision decoding techniques for decoding of the maximum transition run (MTR) codes. Performances of such techniques have been analyzed in combination with error correcting LDPC code over magnetic recording channels, especially the two-track two-head channel model. Ideal E2PR4 track equalization suitable for high density magnetic recording has been used