Electrochemical Transistor(ECT) was reported by David Nilsson in 2002. Later,its dimensios were specified and a SPICE model was developed. The main purpose of this diploma work is to check the performance of electrochemical transistors in amplifier circuits. Simple amplifier circuits were simulated using SPICE model of ECT. Lateral and Vertical structures of electrochemical transistors were patterned on orgacon sheet(provided by AGFA),with various electrolytes(EG010,MS-HEC &amp; MS-L). Characteric curves and time responses of these transistors were studied and then were then used as an active component in single amplifier circuits. Screen printed ECT's were also checked with the best available electrolyte. Behaviour of self made and screen printed ECT's were compared on the basis of on-off ratio,slew rate,frequency response and gain. Screen printed transistors showed promising results having less deterioration with time  but  till  an  an  input  signal  frequency  of  2Hz  only. Mismatch with simulation results and Shockley's equation were other findings after data analysis. <img src="file:///C:/DOCUME%7E1/zia/LOCALS%7E1/Temp/moz-screenshot.jpg" /><img src="file:///C:/DOCUME%7E1/zia/LOCALS%7E1/Temp/moz-screenshot-1.jpg" />

Användningen av strömmande media ökar explosionsartat och är nära knu- tet till utbyggnaden av bredband. Intresset för direktuppspelande video bland kommuner, stat och landsting har ökat på senare år. I dag sänder bl.a. Region Skåne, Uddevalla-, Sigtuna- och Bollnäs kommun direktupp- spelande video från sina kommunfullmäktige.Den här rapporten handlar om Umeå kommuns förutsättningar att sända direktuppspelande video från sin webbplats. Min uppgift blev att undersöka vilka krav kan ställas på en myndighet som sänder video både när det gäller teknik och tillgänglighet.En fördjupning om multicasting görs, då det är en teknik för att drastiskt minska behovet av bandbredd för direktsänd video. Dessutom tas en mobil utrustning fram för att spela in och sända direktuppspelande video över Internet.Avslutningsvis görs en testsändning från den mobila studion.

In future cellular radio networks Radio over Fiber (RoF) is a very attractive technology to deliver microwave and millimeter-wave signals containing broad band multimedia services to numerous base stations of the network. The radio signals are placed on an optical carrier and distributed by means of an optical fiber network to the base stations (BS). In the BS the optical signals heterodyne in a photodiode to produce the radio signals which are then sent via a wireless link to the mobile units (MU). The optical fiber network provides high frequency, wideband, low loss and a means of signal distribution immune to electromagnetic interference. In this thesis, different methods of electrooptical upconversion were investigated. The generation of an optical double-sideband with suppressed carrier (DSB-SC) signal is a straightforward method due to the fact that only one optical modulator driven at half the millimeter-wave frequency is required. One or both sidebands were ASK-modulated with baseband data rates of up to 10 Gbps. Optical single sideband modulation proves to be dispersion resilient as error free transmission was demonstrated after 53 km of single mode fiber transmission for data rates up to 10 Gbps. Wireless links up to 7 m were also demonstrated, proving the feasibility of this approach for broadband wireless inhouse access systems. / Für zukünftige zellulare Funknetze ist „Radio over Fiber (RoF)“ eine sehr attraktive Technologie, um breitbandige Multimedia-Dienste mit Mikro- und Millimeterwellen zu übertragen. Die Funksignale werden dabei auf eine optische Trägerwelle aufmoduliert und mittels eines optischen Fasernetzes zu den Basisstationen (BS) verteilt. In den BS erfolgt die Überlagung der optischen Signale durch eine Fotodiode, um die Funksignale zu erzeugen. Diese werden dann über eine drahtlose Verbindung zu den beweglichen Multimedia-Endgeräten geschickt. Vorteile des optischen Fasernetzes sind Breitbandigkeit, geringe Dämpfung und eine gegenüber elektromagnetischen Störungen immune Signalverteilung. In dieser Arbeit werden verschiedene Methoden der elektrooptischen Aufwärtskonversion erforscht und die wichtigsten Eigenschaften dieser untersucht. Die Erzeugung eines optischen Zweiseitenbandsignales mit unterdrücktem Träger (DSB-SC) ist eine einfache Methode, da nur ein optischer Modulator, betrieben mit der halben elektrischen Trägerfrequenz, benötigt wird. Eine oder beide Seitenbänder konnten mit Bitraten bis zu 10 Gbps amplitudenmoduliert werden. Optische Einseitenbandmodulation ist extrem tolerant bezüglich der chromatischen Dispersion der Faser, wie die fehlerfreie Übertragung nach 53 km Glasfaser beweist. Drahtlose Links bis zu 7 m wurden realisiert und zeigen die Möglichkeit dieser Verfahren für breitbandige drahtlose Inhouse-Zugangssysteme.

Photonic crystals are periodic structures that offers the possibility to control the propagation of light. The revised plane wave method has been implemented in order to compute band structures for photonic crystals. The main advantage of the revised plane wave method is that it can handle lossless dispersive materials. This can not be done with a conventional plane wave method. The computational challenge is comparable to the conventional plane wave method. Band structures have been calculated for a square lattice of cylinders with different parameters. Both dispersive and non-dispersive materials have been studied as well as the influence of a surface roughness. A small surface roughness does not affect the band structure, whereas larger inhomogeneities affect the higher bands by lowering their frequencies.

During the last decades, a global effort has been started towards the implementation of energy efficient electronics. Silicon carbide (SiC), a wide band-gap semiconductor is one of the potential candidates to replace the widespread silicon (Si) which enabled and dominates today’s world of electronics. It has been demonstrated that devices based on SiC lead to a drastic reduction of energy losses in electronic systems. This will help to limit the global energy consumption and the introduction of renewable energy generation systems to a competitive price. Active research has been dedicated to SiC since the 1980’s. As a result, a mature SiC growth technology has been developed and 4 inch SiC wafers are today commercially available. Research and development activities on the fabrication of SiC devices have also been carried out and resulted in the commercialization of SiC devices. In 2011, Schottky barrier diodes, bipolar junction transistors, and junction field effect transistors can be purchased from several electronic component manufacturers. However, the device mostly used in electronics, the metal-oxide-semiconductor field effect transistor (MOSFET) is only recently commercially available in SiC. This delay is due to critical technology issues related to reliability and stability of the device, which still challenge many researchers all over the world. This thesis summarizes the main challenges of the SiC MOSFET fabrication process. State of the art technology modules like the gate stack formation, the drain/source ohmic contact formation, and the passivation layer deposition are considered and contributions of this work to the development of these technology modules is reported. The investigated technology modules are integrated into the complete fabrication process of vertical MOSFET devices. This MOSFET process was tested using cubic SiC (3C-SiC) and hexagonal SiC (4H-SiC) wafers and achieved results will be discussed. / QC 20110415

Denna rapport behandlar en energiundersökning av värmekablar på uppdrag av INEOS ChlorVinyls anläggning i Stenungsund. Eftersom miljön får en större och större betydelse i dagens samhälle försöker alla sektorer i samhället minska sin energiförbrukning. År 2006 använde svensk industri 157 TWh energi och 35,8 % av detta var elenergi. Den kemiska industrin står för 8 % (2006) av Sveriges industriers energiförbrukning och räknas som en energiintensiv bransch. Fabriken i Stenungsund har länge haft ett mycket förmånligt elavtal vilket har gjort att de inte har varit lönsamt att bry sig om att göra relativt småskaliga effektiviseringar. Men nu med ökade energipriser är det aktuellt att titta på vad som kan göras och till vilket pris. Syftet med utredningen är att undersöka om ett annorlunda upplägg av termostaterna som styr värmekablarna gör att man kan spara energi genom att värmen bara ligger på när det verkligen behövs. Genom undersökning och jämförelse av olika termostater koms det fram till att det inte finns noggrannare termostater på marknaden än de som sitter i fabriken. Termostaten till VKB14 är dock felvald. Med hjälp av temperaturstatistik och ett medelvärde av antal timmar under en viss temperatur över de två vintersäsongerna har effektåtgången för VKA14 och VKB14 räknats ut. Genom mätningen av när kontaktorn slår till i VKB14 har det utlästs att detta skåp ligger till 38 % av tiden när temperaturen i intervallet är så hög att det inte borde vara till alls. Om man utgår från att skåpet gör av med 20 000 W när det är igång i onödan, ger detta att det förbrukar 1,3 gånger mer energi per år än vad som behövs vid en temperaturinställning på +5°C.

<p>This thesis considers the problem of making dynamic models for industrial processes by combining physical modelling with experimental data. The focus is on distributed parameter systems, that is, systems for which the model structure involves partial differential equations (PDE). Distributed parameter systems are important in many applications, e.g., in chemical process systems and in intracellular biochemical processes, and involve for instance all forms of transport and transfer phenomena. For such systems, the postulated model structure usually requires a finite dimensional approximation to enable identification and validation using experimental data. The finite dimensional approximation involves translating the PDE model into a set of ordinary differential equations, and is termed model reduction.</p><p>The objective of the thesis is two-fold. First, general PDE model reduction methods which are efficient in terms of model order for a given level of accuracy are studied. The focus here is on a class of methods called moving mesh methods, in which the discretization mesh is considered a dynamic degree of freedom that can be used for reducing the model reduction error. These methods are potentially highly efficient for model reduction of PDEs, but often suffer from stability and robustness problems. In this thesis it is shown that moving mesh methods can be cast as standard feedback control problems. Existing moving mesh methods are analyzed based on tools and results available from control theory, and plausible explanations to the robustness problems and parametric sensitivity experienced with these methods are provided. Possible remedies to these problems are also proposed. A novel moving finite element method, Orthogonal Collocation on Moving Finite Elements (OCMFE), is proposed based on a simple estimate of the model reduction error combined with a low order linear feedback controller. The method is demonstrated to be robust, and hence puts only small demands on the user.</p><p>In the second part of the thesis, the integration of PDE model reduction methods with grey-box modelling tools available for finite dimensional models is considered. First, it is shown that the standard approach based on performing model reduction using some ad hoc discretization method and model order, prior to calibrating and validating the reduced model, has a number of potential pitfalls and can easily lead to falsely validated PDE models. To overcome these problems, a systematic approach based on separating model reduction errors from discrepancies between postulated model structures and measurement data is proposed. The proposed approach is successfully demonstrated on a challenging chromatography process, used for separation in biochemical production, for which it is shown that data collected at the boundaries of the process can be used to clearly distinguish between two model structures commonly used for this process.</p>

<p>In this project Fourier Transform Infrared Spectroscopy is used to investigate a new kind of photodiode that is based on nanowires. The photo current and I-V curves for different temperatures, different applied biases, in darkness and illumination condition have been studied. The experiment was conducted in the temperature range from 78 K (-195ºC) to 300 K (27ºC). These photo diodes are designed to work on NIR wavelengths. The results show some excellent properties, such as high break down voltage, and that is an important advantage for photo detectors, low and constant reverse saturation current (Is). The results show some defects, most of them come from fabrication. The design of the sample is also discussed.</p>

<p>This thesis deals with the electromagnetic compatibility (EMC) problems of distributed electrical networks, especially that caused by lightning to electrified railway. Lightning transients were found to damage important devices that control train movements, causing traffic stoppage and delays. This thesis attempts to develop computational models for identification of parameters influencing the coupling phenomena between those devices and lightning. Some supporting experimental investigations are also carried out. This thesis forms the groundwork on the subject of lightning interaction with the electrified railway networks.</p><p>Lightning induces transient overvoltages in railway conductor systems such as tracks, overhead wires, and underground cables, either due to direct lightning strike to the system or due to the coupling of electromagnetic fields from remote strikes. Models based on multiconductor transmission line theory were developed for calculating the induced voltages and currents. A transmission line return stroke model, that can predict the remote electromagnetic fields comparable to experimental observations, is also developed. </p><p>Earlier works on modeling earth return impedances for transient studies in power distribution systems are not readily applicable for railways for lightning transients, in cases of low earth conductivities found in Sweden and for large variation in conductor heights. For the wires above ground, the ground impedance models were modified for wide range of frequencies, soil conductivities and wide spread of conductor heights. Influences of pole insulator flashovers, pole-footing soil ionizations and interconnections between the conductors on the lightning surge propagation are studied. Wave propagation in buried shielded and unshielded cables with ground return is studied. Simplified, valid and computationally efficient ground impedance expressions for buried and on-ground wires are proposed. A model for the coupling phenomena (transfer impedance) through multiple cable shields with multiconductor core is also proposed. Besides, experimental studies on lightning induced transients entering a railway technical house, failure modes of relay and rectifier units used in the train position/signaling applications for lightning transients are performed. A high frequency circuit model for the booster transformer for lightning interaction studies is developed. The simulation models are being converted to user-friendly software for the practicing engineers of the railway industry.</p>

<p>The present society is highly dependant on complex electronics systems, which have a low damage threshold level. Therefore, there is a high risk of partial or total loss of the system’s electronics when they are exposed to a thunderstorm environment. This calls for a deep understanding on the mechanism related to the interaction of lightning generated electromagnetic fields with various large distributed/scattered systems. To accurately represent the interaction of lightning electromagnetic fields with electrical networks, it is necessary to have return stroke models capable to reproduce the electromagnetic field signatures generated by a lightning flash. Several models have been developed in the recent past to study the field-to-wire coupling mechanism. The most popular, simple and accurate among the available models is the Agrawal et al. model. On the other hand, ATP-EMTP is a well-known transient simulation package widely used by power engineers. This package has various built-in line models like Semlyen, Marti and Noda setups. There is a difficulty in applying the Agrawal et al. model with the built-in line models of ATP-EMTP, as the voltage source due to the horizontal component of electric field in Agrawal et al. model is in series with the line impedance and not in between two transmission line segments. Furthermore, when the electromagnetic field is propagating over a finite conducting ground plane, the soil will selectively attenuate the high frequency content of the electromagnetic field; causing a change in the field wave shape. A finite conducting ground will also produce a horizontal field component at the ground level. Several approximations are available in the literature to obtain the horizontal electric field; namely the wave-tilt and the Cooray-Rubinstein approximation. Consequently, it is important to investigate the change on the induced voltage signature when the power line is located over a finitely conducting ground. Additionally, to provide protection from lightning induced transients it is necessary to use Surge Protective Devices (SPDs) capable of diverting the incoming transients and provide protection level necessary to avoid damage in the equipment. However, standard test procedures of the SPDs do not take into account sub-microsecond structure of the transients. Therefore, to provide the required protection level to sensitive equipments connected to the low voltage power network, it is essential to understand the response of SPDs subjected to high current derivative impulses. This thesis is aimed to investigate the research problems as addressed above. Special attention will be given to a new proposed return stroke model, a simple circuit approach for efficient implementation of Agrawal et al. model using ATP-EMTP, the effect of the soil conductivity on the lightning induced overvoltage signatures and the response of surge protective devices subjected to high current derivative impulses.</p>