The objective of the following research is to investigate the problem of information management and conveyed experience on the World Wide Web (WWW) when multi-modal sensors and media are available. After studying related areas of work about the web and heterogeneous media, it became apparent that one of the main challenges of the area is the semantic unification of heterogeneous media. This thesis will introduce an event-based model to semantically unify media. An event is defined as something of significance that takes place at a given time and location. Using this definition and the corresponding model, a system will be designed to illustrate practical use cases for events.

This dissertation divides into three parts: (a) design and research of asymmetric stepped impedance resonator (SIR); (b) design and fabrication of dual-band and ultra-wide band (UWB) bandpass filters (BPFs) and (c) design and fabrication of millimeter wave filters. (a)design and research of asymmetric stepped impedance resonator. In the first part of the dissertation, we propose an asymmetric SIR, and the effect of electrical length ratio and impedance ratio on the performance of frequency has been discussed in detail. The insertion loss and spurious can be controlled by the structural parameters of asymmetric SIR which decreases the length of resonator effectively and achieves the reduction of whole size. Additionally, this characterization of the asymmetric SIR can be extensively applied on the interconnection of RFIC. (b) design and fabrication of dual-band and ultra-wide band (UWB) filters. In the second part of the dissertation, we propose dual-band and UWB BPFs by using asymmetric SIRs. The designed dual-band BPF is conformed to the standard of wireless local area network (WLAN), and the designed UWB BPF is conformed to the standard that Federal Communications Commission (FCC) defined. The structural parameters of asymmetric SIR can be adjusted accurately by the theoretical equations we calculated. Then, the ideal performance can be achieved. (c) design and fabrication of millimeter wave filters. In the third part of the dissertation, we propose the design of millimeter wave filters fabricated by the standard of complementary metal-oxide semiconductor (CMOS). Asymmetric SIRs are used to design the microwave filter to estimate that the feasibility of system on chip (SoC). Finally, some suggestions are made in the future work on technology for system on chip (SoC).

Ultra Wide Band (UWB) is a short-pulse signal which has extremely potential in wireless communication system due to the advantages of high data rate, better immunity to multipath fading, wide bandwidth, and high capability. According to the Federal Communications Commission (F.C.C.), UWB only can be transmitted in short distance of a few to tens of meters due to low power density (-41.3dBm/MHz). However, optical fiber has low loss and cost and wide bandwidth, so it can be achieved in wide area network. In this work, we propose a novel method to generate optical UWB doublet pulse without complicated setup. When electroabsorption modulator (EAM) integrating a taper optical directional coupler (TODC) was applied field, the transmission loss and coupling would change resulting from the absorption coefficient and effective index of active waveguide with the applied field. So, we used a single mode fiber collecting the power after the device, we could get the valley shape transfer function. Using the transfer function of electro-absorption modulator (EAM) integrating TODC we inject a Gaussian pulse into the EAM in the range of valley shape, and it can transform an electrical pulse into optical UWB doublet pulse by acceptable operating point. Therefore, the optical signals could be transmitted in optical fiber so that it can reduce loss of the electro-optic transformation. Experimentally, the full wave at half maximum of doublet pulse, 10dB bandwidth, fractional bandwidth were 75ps, 7.5GHz, 125%, respectively, and power density was less than -41.3dBm/MHz. These were all meeting the F.C.C. standard. In the future, we will use long distant optical fiber to transmitted UWB signal, and compare with different distance. Finally, we will check the UWB signal can be transmitted in optical fiber to achieve wide range signal transmission by bit error rate test.

Composite propellants are mainly composed of: crystalline oxidizer, metallic fuel, and polymeric binder. Additives, such as plasticizers, catalysts, bonding agents and curing agents may also be incorporated to propellant compositions in small amounts. These ingredients should be mixed rigorously in order to obtain a uniform microstructure throughout the cast propellant profile. The quality of the propellant mixture has to be determined quantitatively to improve the product quality and to reduce costs. In this study, it was aimed to develop an easy, cost effective and rapid test method for determining the optimum mixing conditions for the manufacturing process of solid rocket propellants. An analytical method used in the literature for assessing mixing quality in highly filled polymeric systems is wide-angle x-ray diffractometry (WA-XRD). After finding out the concentration distribution of the components indirectly by WA-XRD, degree of mixing was identified using statistical methods. To accomplish this, series of samples were taken from various locations of the mixing chamber and analyzed by WA-XRD. Degree of mixing calculations based on ratio of intensity arising from aluminum phase over total crystal intensity, and the ratio of intensity arising from ammonium perchlorate phase over total crystal intensity gave satisfactory results. Radial mixing efficiency of planetary mixer was determined, and it was found that mixing at the center was more effective than mixing at the outer regions. Also, by scanning electron microscopy technique (SEM), interactions between binder and solid loading during mixing process were observed. It was seen that polymeric matrix gradually encloses solid particles during mixing.

No description available.

Novel designs of planar antennas including the feed network for improving the antenna performance improvement (CP axial-ratio bandwidth, XPL, port decoupling for dual-polarized operation, and harmonic control) or achieving dual-band operation are presented. This thesis, comprises five sections. Firstly, for obtaining broadband CP designs, the Wilkinson power divider and branch-line coupler are used. The 3-dB axial ratio CP bandwidths of all proposed antennas are larger than 30%. Secondly, the dual broadband patch antennas including a stopband network are proposed. Thirdly, the dual-polarized patch antenna with high XPL and isolation between two ports by using a Wilkinson power divider with a 180¢X phase shift between its two ports is proposed. Fourthly, the dual-band and dual-polarized patch antenna suitable for base-station antenna applications for mobile communications systems is studied. Finally, the harmonic control study of a square microstrip antenna is presented.

The first part of this research focused on wide-cross whole-genome radiation hybrid (WWRH) mapping of the cotton (Gossypium) genome. Radiation hybrid mapping has been used extensively to map the genomes of human and certain animal species, but not plant species. In lieu of in vitro hybrid cell line technologies for plants, we developed a novel approach for radiation hybrid mapping based on wide-cross in vivo hybridization. Flowers from one species of cotton, either G. hirsutum or G. barbadense, were -irradiated and then used to pollinate the other species. The resulting hybrid plants were assessed as a mapping tool. Two WWRH mapping panels were constructed from 5- and 8-krad -irradiation treatments. Both panels demonstrated that the WWRH mapping method can be used to map the cotton genome, and that this method complements traditional linkage mapping approaches. The second part of this research focused on the identification of cold-responsive genes using spotted oligo-gene microarray analysis. Increased cold-tolerance in cotton would promote early and uniform seedling establishment, expand the growing season, decrease susceptibility to fungal infections and certain diseases, and increase fiber yield and quality. BLAST searches of the cotton database using amino acid sequences of 93 drought/cold-related genes from Arabidopsis and several other plant species led to 806 cotton orthologous cDNAs and expressed sequence tags (ESTs). Eight hundred and six cotton 70-mer oligos were designed and included in an oligo-gene microarray containing 1,536 70-mer oligos, each representing a cDNA or EST from cotton, or one of 121 chloroplast genes or 66 mitochondrial genes from Arabidopsis. Thirty-eight cotton cDNAs and ESTs were identified as cold-responsive genes based on experimental treatment and oligo-gene microarray analysis. Expression was up-regulated for 36 genes and down-regulated for two genes by cold treatment. Results from microarray analysis were tested and confirmed by northern blot analysis for 16 genes. Our data suggest that Arabidopsis orthologous genes can be used to identify homologous cotton genes. The oligo-gene microarray is a valid approach to study transcriptional changes in cotton.

<p>Till följd av att användningen av Internet har ökat kraftigt de senaste åren har många företag etablerat sig med webbplatser på detta medium. Ett av hoten mot webbservrar är distribuerade överbelastningsangrepp vilka kan skada ett företags rykte genom att göra deras webbplats otillgänglig. Angreppen har som mål att överskölja en webbserver med data och därmed göra den oanträffbar för andra användare. Det är svårt att skydda sig mot ett angrepp av det här slaget eftersom datamängden är mycket stor och den normala trafiken får svårt att nå webbservern. Målsättningen i detta projekt är att utveckla och undersöka en skyddsmetod som kan användas på en webbserver för att skydda den mot överbelastningsangrepp. Resultatet av utförda simuleringar och en jämförelse med en liknande metod visar att den framtagna skyddsmetoden fungerar som det är tänkt i en simulerad miljö och är konkurrenskraftig</p>

<p>Webbservrar på Internet använder idag dynamiska webbsidor genererade med hjälp av databassystem för sina användare. Detta har lett till en stor belastning på webbservrar och en metod för att minska belastningen är att använda cachning. Detta arbete implementerar och utför tester på en specifik cachningsalgoritm kallad Online View Selection i ett webbspelsscenario. Ett potentiellt problem identifieras hos algoritmen som kan leda till att inaktuell information levereras till klienten och algoritmen modifieras för att hantera problemet. Testresultaten visar att både den modifierade algoritmen och originalet ger likvärdig prestanda. Den modifierade algoritmen visar sig fungera men problemet med den ursprungliga algoritmen uppkommer sällan i webbspelsscenariot.</p>

<p>SiC MESFETs and GaN HEMTs have an enormous potential in high-power amplifiers at microwave frequencies due to their wide bandgap features of high electric breakdown field strength, high electron saturation velocity and high operating temperature. The high power density combined with the comparably high impedance attainable by these devices also offers new possibilities for wideband power microwave systems. In this thesis, Class C switching response of SiC MESFET in TCAD and two different generations of broadband power amplifiers have been designed, fabricated and characterized. Input and output matching networks and shunt feedback topology based on microstrip and lumped components have been designed, to increase the bandwidth and to improve the stability. The first amplifier is a single stage 26-watt using a SiC MESFET covering the frequency from 200-500 MHz is designed and fabricated. Typical results at 50 V drain bias for the whole band are, 22 dB power gain, 43 dBm output power, minimum power added efficiency at P 1dB is 47 % at 200 MHz and maximum 60 % at 500 MHz and the IMD3 level at 10 dB back-off from P 1dB is below ‑45 dBc. The results at 60 V drain bias at 500 MHz are, 24.9 dB power gain, 44.15 dBm output power (26 W) and 66 % PAE.</p><p>In the second phase, two power amplifiers at 0.7-1.8 GHz without feed back for SiC MESFET and with feedback for GaN HEMT are designed and fabricated (both these transistors were of 10 W). The measured maximum output power for the SiC amplifier at Vd = 48 V was 41.3 dBm (~13.7 W), with a PAE of 32 % and a power gain above 10 dB. At a drain bias of Vd= 66 V at 700 MHz the Pmax was 42.2 dBm (~16.6 W) with a PAE of 34.4 %. The measured results for GaN amplifier are; maximum output power at Vd = 48 V is 40 dBm (~10 W), with a PAE of 34 % and a power gain above 10 dB. The SiC amplifier gives better results than for GaN amplifier for the same 10 W transistor.</p><p>A comparison between the physical simulations and measured device characteristics has also been carried out. A novel and efficient way to extend the physical simulations to large signal high frequency domain was developed in our group, is further extended to study the class-C switching response of the devices. By the extended technique the switching losses, power density and PAE in the dynamics of the SiC MESFET transistor at four different frequencies of 500 MHz, 1, 2 and 3 GHz during large signal operation and the source of switching losses in the device structure was investigated. The results obtained at 500 MHz are, PAE of 78.3%, a power density of 2.5 W/mm with a switching loss of 0.69 W/mm. Typical results at 3 GHz are, PAE of 53.4 %, a power density of 1.7 W/mm with a switching loss of 1.52 W/mm.</p> / Report code: LIU-TEK-LIC-2008:32