Minimaks optimalno upravljanje nelinearnim dinamičkim sustavima

Tema ove disertacije je sinteza zakona upravljanja nelinearnim dinamičkim sustavima kojim se utjecaj vanjskih i/ili unutarnjih neodređenosti zadržava ispod dozvoljene granice i osigurava stabilnost zatvorenog sustava. Kao mjeru utjecaja neodređenosti razmatra se L2 pojačanje sustava. Problem pripada području robusne optimizacije, tj. klasi matematičkih problema kod kojih je potrebno istovremeno provesti minimizaciju i maksimizaciju iste funkcije cilja – minimaks optimizacija. U disertaciji se predlaže direktna optimizacija L2 pojačanja bez rješavanja pripadajuće Hamilton-Jacobi-Isaacsove jednadžbe. Provedena je transformacija optimizacije L2 pojačanja iz razlomačkog optimizacijskog problema u parametarski koji uključuje minimaks optimizacijski potproblem, a čije se rješavanje svodi na traženje sedlaste točke diferencijalne igre. Pristup rješavanju problema temelji se na zamjeni komponenata vektora upravljanja i neodređenosti aproksimacijskim funkcijama s linearnom ovisnošću o konačnom broju konstantnih parametara. Parametri aproksimacijskih funkcija upravljačkih varijabli minimiziraju L2 pojačanje, dok parametri aproksimacijskih funkcija neodređenosti maksimiziraju L2 pojačanje. Za računanje ovih parametara predlaže se integracija subgradijentne metode, Newtonove metode, Adamsove metode te automatskog diferenciranja u jedan algoritam. Provedenim numeričkim simulacijama na nelinearnim dinamičkim sustavima kod kojih je mogu´ce analitički rijeˇsiti Hamilton-Jacobi-Isaacsovu jednadžbu te time egzaktno odrediti vektore upravljanja i neodređenosti, pokazane su verzije algoritma koje daju najbolju efikasnost i točnost. Uvjeti stabilnosti za jednu klasu problema izvedeni su primjenom Ljapunovljeve izravne metode. Na kraju je predloženi algoritam primijenjen za sintezu regulatora elektrohidrauličkih sustava. Simulacijskim i eksperimentalnim usporedbama s najčešćim strukturama konvencionalnih regulatora pokazano je da se predloženom strategijom upravljanja mogu ostvariti bolja željena ponašanja

Basic Changes of Individual Farmers in Postwar Development of Yugoslav Society

Farmers experienced a great number of important changes caused by the development of socialism on one hand and changes in the established socialistic social system on the other in the postwar development of Yugoslav society. Namely, the appearance of individual farmers as a basic form of farming was connnected with that aspect in the development of socialistic methods of production that was carried out by means of a series of socio- political measures such as: expropriation, sequestration, agrarian reform, nationalization. The whole social structure of jugoslav society as such was being changed by those measures: farmes, representing majority of population till then, were placed within the frames of individual farming, were »compressed« within the limited farmlands relying on their own labour force. The established social system had another influence as well causing changes in the stratum of individual farmers by means of socio-economic measures fully expressed in industrialization. That is, forces of production were generally underdeveloped and emphasis was on the progress of industry and social sector that were to be used as a »lever« in the realization of socialism, in such a perspective of development, agriculture and individual farmers were comprehended as material and human basis for creating social ownership and modern economy. But socio-economic and socio-political measures were neither of the same nature, nor had the same influence upon farmers in the periods of ethat ism and self-managing socialism. When the socialistic self-management was introduced and later developed those measures became less »compulsary« and more economic. Gradually individual farmers became commodity producers; at the same time their social status became equal to other cathegories of population. On the other hand, under the influence of industrialization farmers started leaving their villages, thus turning from farmers into workers. During the last 35 years the influence of all the factors caused a great number of changes among individual farmers, the most important being the »melting« of farmers as a traditional category. The former patriarchal village has thus undergone deep changes as well

Sinteza regulacijskih sustava primjenom linearnih matričnih nejednadžbi

Tema ovog diplomskog rada je primjena linearnih matričnih nejednadžbi u Hinfty optimizaciji regulacijskih sustava. Formulacija Hinfty problema upravljanja zahtijeva relativno visoku razinu matematičkog razumijevanja prostora analitičkih matričnih funkcija, koji se naziva Hardyjev prostor. Hinfty optimizacija podrazumijeva minimizaciju vršne vrijednosti u amplitudno frekvencijskoj karakteristici sustava. Razmatrane su sinteze regulatora, gdje glavnu ulogu ima čuvena lema pozitivne realnosti. Razvoj vrlo efikasnih numeričkih algoritama za rješavanje linearnih matričnih nejednadžbi glavni je razlog sve većeg interesa za navedenu metodu. Rješavanje tih nejednadžbi ostvaruje se pomoću semidefinitnog programiranja kao generalizacije linearnog programiranja. Analiza stabilnosti navedenih problema temelji se na Ljapunovljevoj direktnoj metodi, kao fundamentalnom pristupu. U radu je provedena Hinfty sinteza upravljanja pozicijom klipa cilindra elektro-hidrauličckog servo sustava. U tu svrhu osim izvoda nelinearanog modela postavljen je i model sustava dobiven linearizacijom oko ravnotežnog stanja. Najprije je projektiran regulator stanja. Kako je uz mjerenje pozicije klipa na laboratorijskom modelu elektro-hidrauličkog servo sustava dostupno mjerenje samo još tlaka u desnoj komori glavnog cilindra, projektiran je estimator varijabli stanja punog reda bez estimacije poremećajne veličine sile tereta. Nadalje, projektiran je dinamički regulator. Izvedene linearne matrične nejednadžbe ovdje se rješavaju upotrebom programskog paketa MATLAB te Yalmip sučelja koje koristi SeDuMi ”solver”. Razvijeni upravljački algoritmi provjereni su eksperimentalno na laboratorijskom modelu elektro-hidrauličkog servo sustava

Evaluation of immunogenic properties of monovalent and polyvalent inactivated bovine virus diarrhea virus (BVDV) vaccines

This study is aimed at evaluating the immunogenicity of two inactivated (mono- and polyvalent) vaccines containing bovine virus diarrhea virus (BVDV) reference and field strains. Three experimental groups were formed: 10 calves vaccinated twice (days 1 and 28) subcutaneously (s/c) with 2 ml of inactivated polyvalent vaccine per animal (Group 1); 10 calves vaccinated twice (days 1 and 28) subcutaneously (s/c) with 2 ml of inactivated monovalent vaccine per animal (Group 2) and 9 unvaccinated calves (Control, Group C). Blood sera were obtained from immunized animals (standard procedure: on days 0, 14, 28, 42 and 56 post-immunization). Geometric mean titer (GMT) values for BVDV neutralizing antibodies were substantially higher in blood sera of calves receiving the inactivated monovalent vaccine. The immune response developed more rapidly in calves immunized with the monovalent vaccine

Cvm study of charge transfer in YBa2Cu3O6+x material

The number of positive holes transferred from the CuOx basal planes to the superconducting CuO2 planes of YBa2Cu3O6+x material was calculated as a function of oxygen content x, by the use of numerical cluster variation method (CVM). The calculations were performed for the set of three different temperatures and for the different values of the parameter ξl which represents the ratio of the number m of divalent oxygen ions in the chain fragment and the total number l of oxygen ions in the chain fragment. The obtained hole count versus x dependence showed no plateau behavior for low temperatures (t=0.25 and t=0.35) while for t=0.45 indication of plateau behavior is present.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Changes in metacognitive processes in the student population detected by the "Metacognition questionnaire"

S. Cartwright-Huttom i A. Wells 1997. godine objavili su Meta-Cognition Questionnaire, koji sadrži 65 čestica sa skalama za odgovaranje Likertova tipa. Prema rezultatima autora, upitnik mjeri pet empirijski odvojenih kategorija vjerovanja i procesa usmjerenih na vlastite misli, tj. metakogniciju. Tih pet kategorija su: pozitivna vjerovanja o zabrinutosti, negativna vjerovanja o nekontroliranosti misli i s tim vezane opasnosti, kognitivna sigurnost, negativna vjerovanja o mislima općenito, uključujući praznovjerje, kaznu i odgovornost, kognitivna osviještenost. Preveden na hrvatski primijenjen je na studentima (N = 163) svih pet godišta studija psihologije u Osijeku. Po prosječnom rezultatu u ovom upitniku 1. i 2. godina studija se ne razlikuju, ali se 1. godina razlikuje i od 3. i od 4. i od 5. godine (prosječni rezultati rastu s godištima studija). Na našim rezultatima dobili smo šest faktora koji su po sadržaju vrlo slični originalnim kategorijama. Rezultati studenata elektrotehničkog studija u Osijeku uklapaju su u opću sliku dobivenu na studentima psihologije. Razlikovanje rezultata u Upitniku metakognicije u prvim godinama studija od kasnijih može imati važnih praktičnih reperkusija u pomaganju studentima pri svladavanju teškoća u studiju.S. Cartwright-Hutton and A. Wells published their Meta-Cognition Questionnaire with 65 items in 1997, each one provided with a Likert type scale for answers. The results collected by the authors showed that the questionnaire measures five empirically separate categories of beliefs and processes concentrated on one’s own thoughts, i.e. metacognition. The five categories were: positive beliefs about worry, negative beliefs about controllability of thoughts and corresponding danger, cognitive confidence, negative beliefs about thoughts in general, including themes of superstitions, punishment and responsibility, and cognitive self-consciousness. The questionnaire translated into Croatian was administered on 163 students of psychology (years of study 1-5) in Osijek. Average results for the first and second year of study do not differ, but the results of the first year students differ from the results of those in the third, fourth and fifth years of study – average results are progressively lower with the years of study. Factor analysis of our results gave six factors whose content is very similar to the original categories (proposed by the authors). Results of students of electrical engineering in Osijek fit into the picture obtained with students of psychology. Differences found between results in the Meta-Cognition Questionnaire obtained by students in the first and second year of study in relation to the results of students in the third, fourth and fifth year of study, could have some important practical implications for help offered to students who encounter difficulties in their studies

Apoptosis Induced by Microtubule Disrupting Drugs in Normal Murine Thymocytes In Vitro

Disruption of cytoplasmic and spindle microtubules by colchicine or nocodazole increases mitotic index, but it also enhances apoptosis in isolated mouse thymocytes; the apoptotic index exceeds 20% after 4 hours of incubation with either drug (5% in controls). Apoptosis was confirmed by DNA fragmentation, and was blocked by calcium chelators and inhibitors of protein synthesis. The apoptotic effect of microtubule disrupting drugs (MOD) was directed to interphase thymocytes and was independent on MOD action on mitotic cells. However, cell death of mitotically arrested cells showed ultrastructural changes similar in many aspects to apoptosis