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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.
1

The Shape Synthesis of Transmitarray Antenna Elements

Aljanah, Abdullah Saad A 16 July 2020 (has links)
Shape synthesis (also called topological synthesis or inverse design in other disciplines) has the potential to provide antenna engineers with a useful addition to their design tools. Transmitarray antennas, which consist of a feed antenna plus a printed planar structure that emulates a lens, are able to provide high directivity antenna performance, and have been the subject of sustained research over the past ten years. The transmitarray lens consists of a lattice of cells, with each cell occupied by an element that includes conductors of specific shape. The feed field incident on each element on the input surface side of the transmitarray is transformed by each element into a field of different amplitude and phase on the output surface side of each element, providing some desired aperture distribution on the output surface. In this thesis we develop a technique, and the overall computational tool to implement it, that fundamentally allows the electromagnetics to dictate how the conducting portions of a 3-layer element must be shaped in order to obtain some specific transmission coefficient. Such shape synthesis of the elements offers the possibility of obtaining elements that have properties not obtainable using conventional elements. These techniques were applied to the shape synthesis of dual-band elements (18 GHz and 24 GHz). A transmitarray using these elements was designed and fabricated, its performance measured and compared to simulated results. An in-depth discussion of the outcome experimentally validates the shape synthesis procedure.
2

Tejpning av sömmar för vattentäta plagg : En studie där tejpade sömmar granskas och testas

Blomqvist, Lise January 2019 (has links)
Denna studie är en kandidatuppsats inom designteknik. Studien görs efter praktik på ett Svenskt företag som producerar arbetskläder. Företaget, som idag är min uppdragsgivare, har ett intresse i att starta egen produktion av produktgruppen 3-lagersjackor. För företaget ses det som en utmaning med produktgruppen, vilket skapade en nyfikenhet hos mig i att utforska ämnet. En 3-lagersjacka kräver tejpning för att bli ett vattentätt plagg, och detta är något som kräver mycket resurser, tid och kunskap. Vid uppstart av ny produktgrupp behöver arbetet starta från grunden med rätt materialval, för att sedan gå vidare till rätt konstruktion och sömnad. Studiens innehåll är vinklat för att undersöka tejpning av 3-lagersmaterial och konstruktion av dess sömmar. Syftet är att ta fram viktigt information- och identifiera vad som är svårt vid tejpning. Studiens resultat bygger till stor del på tester av de tejpade prototyper som skickats för test via ett externt testinstitut. Produktion av produkter bestående av 3-lagersmaterial är beroende av många olika faktorer under både sömnad och konstruktion och blir därför ett brett ämne, men studien har lyckats skrapa lite på ytan och kommit fram till slutsatser som kan vara hjälpsamma vid produktutveckling av 3-lagersprodukter. / This study is a bachelor thesis in design technology. The study is done after an internship at a Swedish company that produces work wear. The company, which today is my client, has an interest in starting its own production of the product group 3-layer jackets. For the company, it is seen as a challenge with the product group, which created a curiosity with me in exploring the subject. A 3-layer jacket requires taping to become a waterproof garment, and this is something that requires a lot of resources, time and knowledge. When starting a new product group, the work needs to start from scratch with the right choice of material, and then move on to the right design and sewing. The content of the study is angled to examine the taping of 3-layer material and the construction of its seams. The purpose is to produce important information and identify what is difficult when taping. The study's results are largely based on tests of the taped prototypes sent for testing via an external test institute. Production of products consisting of 3-layer material is dependent on many different factors during both sewing and construction and therefore becomes a broad subject, but the study has managed to scrape a little on the surface and come to conclusions that can be helpful in product development of 3-layer products.
3

Modellierung, Planung und Gestaltung der Logistikstrukturen kompetenzzellenbasierter Netze

Ackermann, Jörg 09 October 2007 (has links) (PDF)
Kompetenzzellenbasierte (regionale) Netze stellen besondere Anforderungen an die Modellierung, Planung und Gestaltung der Logistikstrukturen. Für die Logistikstrukturmodellierung werden ein generischer Beschreibungsrahmen für produktionslogistische soziotechnische Systeme, Definitionen u.a. zum zentralen Begriff Logistikstruktur sowie ein 3-Ebenen-Modell und Strukturtypen für eine vertiefende Materialflussanalyse und -synthese bereitgestellt. Für die Logistikstrukturplanung wird darauf aufbauend mit der Methode der Integrativen Prozess- und Systemstrukturierung (IPSS) eine Methode zur Behandlung von Strukturierungsproblemen konzipiert, die sowohl speziell für kompetenzzellenbasierte Netze als auch allgemein für Produktions- und Logistiksysteme angewandt werden kann. Für die Logistikstrukturgestaltung werden unter Modell- und Methodenverwendung Szenarien sowie Gestaltungs- und Vorzugslösungen für den Materialfluss abgeleitet. / Competence-cell based (regional) networks put special requirements on the modelling, planning and design of logistics structures. For the modelling of logistics structures, a generic description framework for production logistic sociotechnical systems, definitions for, amongst others, the central term logistics structure as well as a 3-layer-model and structure types for a more detailed material flow analysis and synthesis are provided. For the planning of logistics structures, the Method of Integrative Process and System Structuring (IPSS) is developed as a method for handling structuring problems. It can be applied especially to Competence-cell based networks as well as generally to production and logistics systems. For the design of logistics structures, scenarios as well as design and preference solutions for the material flow are derived.
4

Modellierung, Planung und Gestaltung der Logistikstrukturen kompetenzzellenbasierter Netze

Ackermann, Jörg 05 September 2007 (has links)
Kompetenzzellenbasierte (regionale) Netze stellen besondere Anforderungen an die Modellierung, Planung und Gestaltung der Logistikstrukturen. Für die Logistikstrukturmodellierung werden ein generischer Beschreibungsrahmen für produktionslogistische soziotechnische Systeme, Definitionen u.a. zum zentralen Begriff Logistikstruktur sowie ein 3-Ebenen-Modell und Strukturtypen für eine vertiefende Materialflussanalyse und -synthese bereitgestellt. Für die Logistikstrukturplanung wird darauf aufbauend mit der Methode der Integrativen Prozess- und Systemstrukturierung (IPSS) eine Methode zur Behandlung von Strukturierungsproblemen konzipiert, die sowohl speziell für kompetenzzellenbasierte Netze als auch allgemein für Produktions- und Logistiksysteme angewandt werden kann. Für die Logistikstrukturgestaltung werden unter Modell- und Methodenverwendung Szenarien sowie Gestaltungs- und Vorzugslösungen für den Materialfluss abgeleitet. / Competence-cell based (regional) networks put special requirements on the modelling, planning and design of logistics structures. For the modelling of logistics structures, a generic description framework for production logistic sociotechnical systems, definitions for, amongst others, the central term logistics structure as well as a 3-layer-model and structure types for a more detailed material flow analysis and synthesis are provided. For the planning of logistics structures, the Method of Integrative Process and System Structuring (IPSS) is developed as a method for handling structuring problems. It can be applied especially to Competence-cell based networks as well as generally to production and logistics systems. For the design of logistics structures, scenarios as well as design and preference solutions for the material flow are derived.

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