Problem zaleta regulatora i izvedbe funkcije za njegovo sprečavanje

Glavni zadatak ovog rada bio je prikazati i usporediti kakvoću regulacije u regulacijskim krugovima prilikom nastupanja efekta zaleta kada regulator posjeduje funkciju za sprječavanje. Problem zaleta regulatora (wind-up effect) je nepoželjan efekt u regulacijskim krugovima koji se događa kod regulatora koji imaju integralno vladanje, a u regulacijskom krugu postoji amplitudno ograničenje. Kada izvršni član uđe u ograničenje povratna veza se prividno prekida i sustav radi u otvorenoj pelji što izaziva drastično pogoršanje kakvoće regulacije. Kako bi se smanjio utjecaj takvog efekta potrebno je primjeniti metode sprječavanja efekta zaleta. U praksi se najčešće koriste tri metode: povratno integriranje, uvjetno integriranje i automatsko resetiranje. Simulacijom u Matlabu prikazana je efikasnost svake metode na dva tipa regulacijskih krugova s PT2 i IT1 procesima, koji se upravljaju s PI regulatorom.The main task of this thesis was to show and compare quality in regulation circuits during appereance of windup effect when regulator has function for it's prevention. Wind-up problem of regulator is undesirable effect in regulation circuits which is happening when regulator have integrally conduct and when there is amplitude limitation. When control signal enters the restriction feedback stops and system works in open loop which causes drastic deterioration quality of regulation. To reduce the imapct of that effect it is necessary to apply methods that are developed for that cases. The most commonly used methods in praxis are: back calculation, conditional integration and automatic reset. Simulation models that were made in Matlab shows the efficiency of every methods which are implemented on regulation circuits with PI regulator and PT2, IT1 processes and quality of regulation in graphic form and results in numeric indices

Aspects of Convergence of Random Walks on Finite Volume Homogeneous Spaces

We investigate three aspects of weak* convergence of the $n$-step distributions of random walks on finite volume homogeneous spaces $G/\Gamma$ of semisimple real Lie groups. First, we look into the obvious obstruction to the upgrade from Cesaro to non-averaged convergence: periodicity. We give examples where it occurs and conditions under which it does not. In a second part, we prove convergence towards Haar measure with exponential speed from almost every starting point. Finally, we establish a strong uniformity property for the Cesaro convergence towards Haar measure for uniquely ergodic random walks.Comment: 20 pages; fixed a small gap in the proof of the main result in section

Validating The Use Of Sex Steroid Hormones Extracted From The Skeletal Muscle Tissue Of The Atlantic Sharpnose Shark (Rhizoprionodon Terraenovae), Spiny Dogfish (Squalus Acanthias), And The Little Skate (Leucoraja Erinacea) To Assess Reproductive Status In Elasmobranch Fishes

Currently, circulating concentrations of plasma steroid hormones are used as one means to assess reproductive maturity and reproductive cycles in elasmobranchs. However, obtaining blood non-lethally from large and/or endangered species can be problematic because of difficulties involved with specimen handling. Thus, there is a need to develop new approaches and techniques to study the reproductive biology of elasmobranchs. Previous work conducted on other classes of vertebrates has demonstrated that steroid hormones can be successfully extracted from muscle tissue. The process of collecting muscle tissue samples is quick, minimally invasive, and may be conducted without removing the animal from the water, facilitating its use on larger, and/or endangered species of elasmobranchs. Thus, the objective of the current study was to develop and validate a method for extracting steroid hormones from the skeletal muscle tissue of the lecithotrophic aplacental viviparous spiny dogfish (Squalus acanthias), the oviparous little skate (Leucoraja erinacea), and the placental viviparous Atlantic sharpnose shark (Rhizoprionodon terraenovae). The results suggest that concentrations of progesterone [P4], testosterone [T], and estradiol [E2] present in skeletal muscle of the three aforementioned species can be successfully quantified by radioimmunoassay. Additionally, there were significant correlations between plasma and muscle E2 concentrations in S. acanthias, as well as plasma and muscle P4, T and E2 concentrations in R. terraenovae and L. erinacea. Furthermore, concentrations of muscle P4, T and E2 were determined to be statistically significant indicators of reproductive status. The results of the current investigation demonstrated that skeletal muscle, which can be non-lethally harvested, is a viable and practical alternative to collecting blood samples for studying the reproductive biology of elasmobranchs

“Beyond My Imagination”: Learning the Sociology of Poverty Through Service After the Tuscaloosa Tornado

In recent years, educators from diverse academic disciplines have created service learning courses in response to natural disasters. However, sociology courses have been slow to integrate service learning after disasters. In this paper, the learning experiences of fourteen students enrolled in a service learning course during the Fall 2011 semester at the University of Alabama are analyzed, four months after the April 27, 2011 tornado event. In this course, entitled Gender and Poverty, students were required to volunteer 30 hours over a 10-week period with an organization that assisted tornado survivors in addition to attending weekly class meetings and completing class assignments. Despite initial difficulties finding interactive service experiences for the students, post-tests and journal assignments indicated a shift in students’ explanations of poverty from mostly individual-level explanations to structural explanations of poverty. The service experience also emotionally transformed the students, who through their service efforts, developed empathy for storm survivors