PSpice library of circuit elements with selfheating

Tato bakalářská práce je věnována tématu Knihovna prvků s vlastním ohřevem pro PSpice, který se zabývá teplotním nedostatkem v PSpice a návrhem modelů rezistoru, diody a tranzistor s ošetřením tohoto problému. Práce teoreticky popisuje elektrotepelnou analogii, vytvořením tepelného náhradního obvodu a teorie tvorby modelů diody a tranzistoru. Dalším krokem je teoretický postup návrhu obecného obvodu, teorie systému knihoven a netlistu v PSpice a popis, jakými způsoby lze vytvářet makroobvody. Vlastním řešením celé práce je vytvoření modelu rezistoru, diody a tranzistoru s vlastním ohřevem. Dále jsou zobrazeny výsledky simulací těchto modelů. Model tranzistoru je odzkoušen na koncovém stupni nízkofrekvenčního zesilovače společně s modelem chladiče.This bachelor´s thesis is devoted to the topic PSpice library of circuit elements with selfheating, which deals with the lack of temperature in the PSpice and design models of the resistor, diode and transistor to the treatment of this problem. The thesis describes theoretically Electrothermal analogy, creating a thermal equivalent circuit model and the theory of creation diodes and transistors. The next step is a theoretical design procedure of general circuit, theory of system libraries and netlist in PSpice and a description of ways of creating subcircuits. Their own solution the whole thesis is creating a model of a resistor, diode and transistor with self-heating. Furthermore, the results are shown simulations of the models. Transistor model is tested on the output stage audio amplifier together with a model heatsink.

Komparativna analiza studija glazbene pedagogije u Zagrebu i Grazu

Ovaj rad bavi se usporedbom studija Glazbene pedagogije na Muzičkoj akademiji Sveučilišta u Zagrebu i studija Glazbenog odgoja na Sveučilištu za glazbu i izvedbene umjetnosti u Grazu. Prikazan je nastavni plan i program oba studija, koji je zatim uspoređen uz detaljan opis kolegija. Ukazuje se na njihove sličnosti i razlike, te prednosti i mane, uzimajući u obzir okolnosti kojima su izložene.The aim of this paper is to compare two study programmes: Music Pedagogy at the Academy of Music in Zagreb and Music Education at the University of Music and Performing Arts Graz. The curriculum of both study programmes is presented, then compared with detailed course description. The paper points to their similarities and differences, as well as their advantages and disadvantages, taking into account the circumstances they are exposed to

Elektromagnetsko polje na frekvenciji mobilnih telefona (900 MHz) izaziva stres i modifikacije DNA u gujavici Eisenia fetida

Eisenia fetida earthworms were exposed to electromagnetic field (EMF) at a mobile phone frequency (900 MHz) and at field levels ranging from 10 to 120 V m-1 for a period of two hours (corresponding to specific absorption rates ranging from 0.13 to 9.33 mW kg-1). Potential effects of longer exposure (four hours), field modulation, and a recovery period of 24 h after two hours of exposure were addressed at the field level of 23 V m-1. All exposure treatments induced significant DNA modifications as assessed by a quantitative random amplified polymorphic DNA-PCR. Even after 24 h of recovery following a two hour-exposure, the number of probe hybridisation sites displayed a significant two-fold decrease as compared to untreated control earthworms, implying a loss of hybridisation sites and a persistent genotoxic effect of EMF. Expression of genes involved in the response to general stress (HSP70 encoding the 70 kDa heat shock protein, and MEKK1 involved in signal transduction), oxidative stress (CAT, encoding catalase), and chemical and immune defence (LYS, encoding lysenin, and MYD, encoding a myeloid differentiation factor) were up-regulated after exposure to 10 and modulated 23 V m-1 field levels. Western blots showing an increased quantity of HSP70 and MTCO1 proteins confirmed this stress response. HSP70 and LYS genes were up-regulated after 24 h of recovery following a two hour-exposure, meaning that the effect of EMF exposure lasted for hours.U ovom istraživanju gujavice vrste Eisenia fetida bile su izložene elektromagnetskom polju (EMP) na frekvenciji mobilnih telefona (900 MHz) te poljima jačine 10 do 120 V m-1 u dvosatnom razdoblju (što odgovara specifičnim ratama apsorpcije od 0,13 do 9,33 mW kg-1). Utjecaj dužeg izlaganja (4 sata), modulacije polja te vrijeme oporavka od 24 sata nakon dva sata izlaganja proučavan je pri jačini polja od 23 V m-1. Metoda kvantitativne nasumično umnožene polimorfne DNA (engl. quantitative random amplified polymorphic DNA – qRAPD) otkrila je značajne modifikacije DNA na svim proučavanim tretmanima. Čak i nakon 24-satnog oporavka broj hibridizacijskih mjesta bio je dvostruko manji u odnosu na broj zabilježen u kontrolnim gujavicama, što upozorava na gubitak hibridizacijskih mjesta i na dugoročan utjecaj EMP-a. Ekspresija gena uključenih u odgovor na stres (HSP70: kodira za 70kDa heat shock protein i MEKK1: uključen u provođenje signala), oksidacijski stres (CAT: kodira za katalazu) te kemijsku i imunosnu obranu (LYS: kodira za lysenin i MYD: kodira za faktor mijeloidne diferencijacije) bila je povišena nakon izlaganja polju jačine 10 V m-1 te moduliranome polju jačine 23 V m-1. Western blot analiza potvrdila je odgovor na stres detekcijom povišene količine HSP70 i MTCO1 proteina. HSP70 i LYS geni imali su povišenu ekspresiju i nakon razdoblja oporavka, što upućuje na dugotrajan utjecaj EMP-a

različiti učinci radiofrekvencijskog elektromagnetskog polja na ličinke medonosne pčele (Apis mellifera) u ovisnosti o oblikovanju pokusa

Exposure to radiofrequency electromagnetic fields (RF-EMF) at the operating frequencies of different communication devices can cause various biological effects. However, there is a lack of studies on the oxidative stress response and genotoxicity in the honey bee (Apis mellifera) after exposure to RF-EMF. In this study, we investigated the oxidative stress and DNA damage in honey bee larvae situated in waxcomb cells, exposed to modulated RF-EMF 23 Vm-1. The glutathione S-transferase activity decreased, whereas the catalase activity increased significantly in the honey bee larvae upon RF-EMF exposure. Superoxide dismutase activity, the level of lipid peroxidation, and DNA damage were not statistically altered in exposed honey bee larvae when compared to the control group. These results suggest that the biological effects of modulated RF-EMF in honey bee larvae depend on the exposure design.Izloženost radiofrekvencijskom elektromagnetskom polju (RF-EMF) na radnoj frekvenciji različitih komunikacijskih uređaja može imati razne biološke učinke. Nedostaju istraživanja odgovora na oksidacijski stres i genotoksičnost u medonosne pčele (Apis mellifera) poslije izloženosti RF-EMF-u. U ovom je radu istražen oksidacijski stres i DNA oštećenja u ličinkama medonosnih pčela smještenih u stanicama saća i izloženih modulirajućem RF-EMF 23 Vm-1. Aktivnost glutation S-transferaze smanjena je, dok je aktivnost katalaze značajno povećana u ličinkama medonosnih pčela izloženih RF-EMF-u. Nije bilo statistički značajne promjene u aktivnosti superoksid-dismutaze, razini lipidne peroksidacije i DNA oštećenju između ličinaka medonosne pčele i kontrolne skupine. Ovi rezultati pokazuju da biološki učinci modulirajućeg RF-EMF u ličinkama medonosne pčele ovise o oblikovanju izloženosti

Fabrication by Spin-Coating and Optical Characterization of Poly(styrene-co- acrylonitrile) Thin Films

The optical characteristics of poly(styrene-co- acrylonitrile) thin films obtained by spin- coating of polymer blend in tetrahydrofuran were investigated by spectroscopic ellipsometry, spectrophotometry, and atomic force microscopy. Film thickness can be broadly varied by changing the polymer concentration.The film thickness dependence on PSAN concentration shows a non- linear behavior that can be explained by a concentration-dependent viscosity. According to previously proposed models, prepared solutions are close to the concentrated solution regime. Films show a broad transparency range and refractive index independent of film thickness. The refractive index values range from 1.55 to 1.6 in the visible range. Thermal treatment revealed good stability of the films up to 220 °C and a progressive deterioration for larger temperatures, with evident damage at 300 °C. UV- induced photodegradation was observed and results showed a progressive decrease of transmittance in the range between 200 and 300 nm but PSAN thin films show no changes when exposed to light from a solar illuminator. These investigations indicate that PSAN is an excellent candidate for thin film polymer-based optical uses like interference coatings or encapsulation of solar cell

Influence of RF excitation during pulsed laser deposition in oxygen atmosphere on the structural properties and luminescence of nanocrystalline ZnO:Al thin films

Thin ZnO:Al layers were deposited by pulsed laser deposition in vacuum and in oxygen atmosphere at gas pressures between 10 and 70 Pa and by applying radio-frequency (RF) plasma. Grazing incidence small angle x-ray scattering and grazing incidence x-ray diffraction (GIXRD) data showed that an increase in the oxygen pressure leads to an increase in the roughness, a decrease in the sample density, and changes in the size distribution of nanovoids. The nanocrystal sizes estimated from GIXRD were around 20 nm, while the sizes of the nanovoids increased from 1 to 2 nm with the oxygen pressure. The RF plasma mainly influenced the nanostructural properties and point defects dynamics. The photoluminescence consisted of three contributions, ultraviolet (UV), blue emission due to Zn vacancies, and red emission, which are related to an excess of oxygen. The RF excitation lowered the defect level related to blue emission and narrowed the UV luminescence peak, which indicates an improvement of the structural ordering. The observed influence of the deposition conditions on the film properties is discussed as a consequence of two main effects: the variation of the energy transfer from the laser plume to the growing film and changes in the growth chemistry

Depth profiling of Cr-ITO dual-layer sample with secondary ion mass spectrometry using MeV ions in the low energy region

This work explores the possibility of depth profiling of inorganic materials with Megaelectron Volt Secondary Ion Mass Spectrometry using low energy primary ions (LE MeV SIMS), specifically 555 keV Cu ²⁺ , while etching the surface with 1 keV Ar ⁺ ions. This is demonstrated on a dual-layer sample consisting of 50 nm Cr layer deposited on 150 nm In2O5Sn (ITO) glass. These materials proved to have sufficient secondary ion yield in previous studies using copper ions with energies of several hundred keV. LE MeV SIMS and keV SIMS depth profiles of Cr-ITO dual-layer are compared and corroborated by atomic force microscopy (AFM) and time-of-flight elastic recoil detection analysis (TOF-ERDA). The results show the potential of LE MeV SIMS depth profiling of inorganic multilayer systems in accelerator facilities equipped with MeV SIMS setup and a fairly simple sputtering source