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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Optical millimeter-wave signal generation, transmission and processing for symmetric super-broadband optical-wireless access networks

Jia, Zhensheng 01 July 2008 (has links)
Three 40/60-GHz optical-wireless bidirectional architectures are designed with a centralized light source in the central office based on wavelength reuse. Three super-broadband access networks are proposed and experimentally demonstrated for simultaneously delivering wired and wireless services over an optical fiber and an air link in a single transport platform. The transport feasibility in metro and wide-area access networks with multiple reconfigurable optical add-drop multiplexers (ROADMs) nodes is explored for 40-GHz and 60-GHz optical millimeter-wave signals. Additionally, the optical-wireless systems using the orthogonal frequency division multiplexing (OFDM) modulation format are analytically and experimentally demonstrated to mitigate the chromatic dispersion in optical fiber. This thesis also successfully implements the testbed trial for the delivery of uncompressed 270-Mb/s standard-definition television (SDTV) and 1.485-Gb/s high-definition television (HDTV) video signals over optical fiber and air links. The demonstration represents the first ever reported real applications over hybrid wired and wireless access networks, showing that our developed up-conversion schemes and designed architectures are highly suitable for super-broadband applications in next-generation optical-wireless access networks.
32

Digitalisera tryckmätning över filter hos AstraZeneca / Digitalization of pressure measurement over filters at AstraZeneca

Hosseiny, Heshmat, Köpsén, Emil January 2023 (has links)
AstraZeneca är ett medicinskt företag lokaliserat i Södertälje som har cirka 900 luftfilterboxar hos sin anläggning i Gärtuna. Dessa filterboxar kan vara opraktiska att hålla koll på eftersom de är utspridda uppe på vindarna, samt att det behövs bra framförhållning vid filterbyten eftersom vissa filter innehåller farliga ämnen. Filterboxar är utrustade med analoga tryckmätare vilket innebär att det kan bli omständigt för personalen att övervaka filtrets tryckfall. Målet med det här examensarbetet är att hitta en digital lösning som underlättar övervakningen av tryckfall över filter i realtid, samt informerar via sms eller mejl när det är dags att planera in filterbyte. Visionen är att det ska bli enklare att få en bild över luftfiltrets underhållsmässiga skick. Genom att jämföra olika produkter och delta i regelbundna möten med IT kunnig personal valdes en lämplig produkt. Projektet har arbetat metodiskt och strukturerat genom att följa projektmodellen projekt case där verktygen GANTT-schema, SWOT-analys, FMEA och maxiriskmetoden har använts. Projektet resulterade i användningen av digitala differentialtryckgivare som mäter tryckfallet över filter. Differentialtryckgivaren samlar data som sedan skickas via radiofrekvens till en Ethernet gateway som är trådad in till AstraZenecas segregerade nätverk så kallat FAB-net. Därefter förs datan från ethernet gatewayen till mjukvara. I mjukvaran kommer AstraZenecas filtergrupp kunna se över tryckfall hos de olika filtrena i filterboxarna. Detta kommer underlätta personalens arbete och eventuellt spara AstraZeneca tid och pengar. / AstraZeneca is a medical company located in Södertälje that has around 900 air filter boxes at its facility in Gärtuna. These filter boxes can be impractical to keep track of as they are scattered up in the attics and good foresight is needed for multiple filter changes as some filters contain harmful substances. Filter boxes are equipped with analog pressure gauges, which means that there is a lot of walking for the staff in order to monitor the filter's pressure drop. The goal of this thesis is to find a digital solution that can facilitate the monitoring of pressure drops across filters in real time and that also informs by text message or email when it is time to schedule a filter change. The vision is that it will be easier to get a digital image of the maintenance condition of the air filter. By comparing different products and participating in regular meetings with AstraZeneca's IT personnel, a suitable product was chosen. The project has worked methodically and structured by following the project model project case where tools such as GANTT chart, SWOT analysis, FMEA and maxirisk method have been used. The project resulted in the use of digital differential pressure sensors that measure the pressure drop across filters. The differential pressure sensor collects data which is then sent by radio frequency to an ethernet gateway which is wired into AstraZeneca's segregated network called FAB-net. The data is then transferred from the ethernet gateway to the software. AstraZeneca's filter group will be able to review the pressure drop of the various filters within the software, which will facilitate their way of working and potentially save AstraZeneca time and money.

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