Most major sports today use a dedicated ball or projectile with specific shape, size, and surface geometry, except for soccer. Over the history of the sport, the surface geometry and design stayed relatively unchanged, sewn together using 32 pentagonal and hexagonal panels. However, recent innovations in panel designs differ substantially from the traditional 32 panel ball. The effects these new designs have on the aerodynamic characteristics of the ball have remained largely unknown, even with the influx of experimental research completed in the past decade. Experimental studies have been broad in scope, analyzing an entire ball in wind tunnels or full flow paths in trajectory analyses. Computational efforts have been too assumptive in flow conditions, such as a fully turbulent flow field, which has not yielded accurate representations of the flow phenomenon. This study investigates the aerodynamic effects of the seam on a two-dimensional representation of a non-rotating soccer ball using Computational Fluid Dynamics (CFD). By applying a transitional solver to the narrowed scope of a two-dimensional flow domain, with a single seam in cross-flow, the effects of the seam on the boundary layer and overall transient flow structure can be more accurately modeled. Data analysis suggests the seam produces a local effect on skin friction, however, that effect does not materialize into a premature boundary layer transition or delayed separation point, as predicted by literature. A detailed flow visualization is consistent with this result, displaying expected symmetric vortex shedding similar to a smooth cylinder, but not fully capturing the effects of the seam, reinforcing the need for expanding computational research efforts in this field.

<p>The aim of the research work presented here, is to contribute to the adaptation of electronic packaging towards the needs of high frequency applications. As the field of electronic packaging stretches over several very different professional areas, it takes an interdisciplinary approach to optimize the technology of electronic packaging. Besides this, an extensive knowledge of industrial engineering should be an essential part of this undertaking to improve electronic packaging. Customary advances in technology are driven by new findings and a continuous development of processes in clearly defined fields. However, in the field of the higher levels of the interconnection hierarchy, that is external to the chip level interconnections and chip packaging, it is supposed that a wide combination of disciplines and technical creativity, instead of advanced technology in a special area should produce most added value.</p><p>The thesis is divided into five areas, interlinked by the overall aim of there advantages to the common goal. These areas are the Printed Wiring Board (PWB) technology, PWB connections using flexible printed circuit boards, multiconductor cable connections, shielded enclosures and the related EMC issues, and finally the cooling of electronics. A central issue was to improve the shielded enclosures to be effective also at very high frequencies; it will be shown that shielded enclosures without apertures can cope with frequencies up to and above 15 GHz. Due to this enclosure without apertures, it was necessary to develop a novel cooling structure. This cooling structure consists of a heat sink where the PCB’s are inserted in close contact to the cooling fins on one side, whereas the other side of the heat sink is cooled by forced ventilation. The heat transfer between these parts is completely inside the same body. Tests carried out on a prototype have shown that the performance of the cooling structure is satisfactory for electronic cooling.</p><p>Another problem area that is addressed are the interconnect problems in high frequency applications. Interconnections between parts of a local electronic system, or as within the telecom and datacom field between subscribers, are commonly accomplished by cable connections. In this research work multiconductor cables are examined and a patented novel cable-connector for high frequency use is presented. Further, an experimental complex soldering method between flexible printed circuits boards and rigid printed circuits boards, as part of connections between PCBs, is shown. Finally, different sectors of the PCB technology for high frequency applications are scrutinized and measurements on microstrip structures are presented.</p>

The aim of the research work presented here, is to contribute to the adaptation of electronic packaging towards the needs of high frequency applications. As the field of electronic packaging stretches over several very different professional areas, it takes an interdisciplinary approach to optimize the technology of electronic packaging. Besides this, an extensive knowledge of industrial engineering should be an essential part of this undertaking to improve electronic packaging. Customary advances in technology are driven by new findings and a continuous development of processes in clearly defined fields. However, in the field of the higher levels of the interconnection hierarchy, that is external to the chip level interconnections and chip packaging, it is supposed that a wide combination of disciplines and technical creativity, instead of advanced technology in a special area should produce most added value. The thesis is divided into five areas, interlinked by the overall aim of there advantages to the common goal. These areas are the Printed Wiring Board (PWB) technology, PWB connections using flexible printed circuit boards, multiconductor cable connections, shielded enclosures and the related EMC issues, and finally the cooling of electronics. A central issue was to improve the shielded enclosures to be effective also at very high frequencies; it will be shown that shielded enclosures without apertures can cope with frequencies up to and above 15 GHz. Due to this enclosure without apertures, it was necessary to develop a novel cooling structure. This cooling structure consists of a heat sink where the PCB’s are inserted in close contact to the cooling fins on one side, whereas the other side of the heat sink is cooled by forced ventilation. The heat transfer between these parts is completely inside the same body. Tests carried out on a prototype have shown that the performance of the cooling structure is satisfactory for electronic cooling. Another problem area that is addressed are the interconnect problems in high frequency applications. Interconnections between parts of a local electronic system, or as within the telecom and datacom field between subscribers, are commonly accomplished by cable connections. In this research work multiconductor cables are examined and a patented novel cable-connector for high frequency use is presented. Further, an experimental complex soldering method between flexible printed circuits boards and rigid printed circuits boards, as part of connections between PCBs, is shown. Finally, different sectors of the PCB technology for high frequency applications are scrutinized and measurements on microstrip structures are presented. / QC 20101006

In this thesis work, importance of radome structures for antenna systems is emphasized. Structural and electromagnetic requirements of various types of radome structures are analyzed and specific properties are given. Electromagnetic scattering analysis of sandwich type radome seams has been done. Total antenna system far electromagnetic field expression, which is the combination of original antenna far electromagnetic field and the scattered electromagnetic field of the framework of the sandwich radome structure has been found and simulated. To enhance electromagnetic transparency of sandwich type radomes two sandwich radome design methods are proposed which are expressed as Geometrical Randomization and Tuning the Seams. Electromagnetic scattering level minimizations advanced by these design methods are presented with related simulations.

Made available in DSpace on 2014-07-29T15:03:30Z (GMT). No. of bitstreams: 1 Gregorio Sandro Vieira.pdf: 2051926 bytes, checksum: 3f1641739e31761ce674bd4e06e87c0d (MD5) Previous issue date: 2010-03-19 / This paper presents an experimental study done in bi-metal beams supported from 3000 mm in length, composed of thin-walled, resulting in a section of the "I". The beams were formed from the welding of the souls of two metal profiles of type U. The variables were the type of profile used, the quantity and positioning of the welded seams. The beams were divided into two groups where the first group used profiles of the "U" and the second group used simple profiles such as "U" stiff. Each group was composed of three beams so that a beam does not receive any amendment, another amendment received a girder high up in the middle of the span, and the third top beam was amended so that the position would result in an amendment pierced. The applied load was set so as to leave the central part of the beams, which served as a region of the present study, working in pure bending. Test results for beams without amendment were compared with the theoretical results and served as a parameter to compare the behavior of these beams, with beams that were amended. Also a comparison was made between the bearing capacity of the two groups of beams. The experiments showed that, by making the proper control of welding there is no problem in making welded seams in the rafters. We also observed that the simple addition of stiffening beams tables promotes a significant increase in the bearing capacity. There was no correlation between failure modes provided theoretically and observed experimentally, thus, further studies are needed to properly analyze the theoretical results with experimental results. / Este trabalho apresenta um estudo experimental feito em vigas metálicas bi-apoiadas de 3000 mm de comprimento, compostas por perfis formados a frio, resultando em uma seção do tipo I . As vigas foram formadas a partir da soldagem das almas de dois perfis metálicos do tipo U. As variáveis estudadas foram o tipo de perfil utilizado, a quantidade e o posicionamento das emendas soldadas. As vigas foram dividas em dois grupos onde, o primeiro grupo utilizou perfis do tipo U simples e o segundo grupo utilizou perfis do tipo U enrijecido. Cada grupo foi composto por três vigas de forma que uma viga não recebeu nenhum tipo de emenda, outra viga recebeu uma emenda de topo no meio do vão, e a terceira viga recebeu emendas de topo de forma que o posicionamento resultasse em uma emenda trespassada. O carregamento aplicado foi disposto de forma a deixar a parte central das vigas, que serviu como região de estudo deste trabalho, trabalhando em flexão pura. Os resultados dos ensaios para as vigas sem emenda foram comparados com os resultados teóricos e serviram de parâmetro para a comparação do comportamento destas vigas, com o das vigas que receberam emendas. Também foi feita uma comparação entre a capacidade portante dos dois grupos de vigas. Os experimentos constataram que, fazendo-se o controle adequado da soldagem não há problemas em se fazer emendas soldadas nas vigas. Também foi observado que o simples acréscimo de enrijecimento nas mesas das vigas promove um acréscimo significativo da capacidade portante. Não houve concordância entre os modos de ruptura previstos teoricamente e os observados experimentalmente, assim, são necessários mais estudos para se analisar adequadamente os resultados teóricos com os resultados experimentais.

Syftet med examensarbetet har varit att hitta lämpliga textila material för en klimatsmart rullgardin med flera olika skikt skapad av företaget Climate Curtains, samt att ta fram en väl genomtänkt design som är anpassad för miljön den är tänkt att hänga i, nämligen skolor och kontor. Den klimatsmarta rullgardinen ska ha ett absorberande mattsvart material närmast glasfönstret för att fånga upp UV-strålning och därmed bli varmt. Värmen ska sedan föras in i rummet med hjälp av fläktar som sitter monterade inuti gardinstången. En solcellsfilm ska även fästas på skiktet närmast fönstret och har därför tagits med i beräkningarna, dock är solcellsfilmen fortfarande under utveckling. Tanken med solcellsfilmen är först och främst att den ska förse fläktarna med energi men även webbelysning eller laddning av mobil och dator vid överflöd av energi ska vara möjligt. Rullgardinen ska även ha ett vitt reflekterande material in mot rummet för att möjligheten att vända gardinen ska finnas. Under sommartid kan den vända gardinen istället reflektera bort UV-ljus. Mellan dessa två skikt ska ett antal mellanskikt hänga för att erhålla bättre isoleringsegenskaper samtidigt som buller och oljud minskas. Det har även varit relevant att undersöka om flamskyddsmedel bör användas eftersom att gardinen ska hänga i offentliga miljöer. Examensarbetet har bestått av litteraturstudier och praktiska experiment. Experimenten som utfördes var nöthärdighets-, flexibilitets-, reflektionstest samt säkerställning av färg. Materialen som har undersökts har alla varit gjorda av 100% polyester och två alternativa material valdes för vardera skikt. Polyester valdes till alla skikt dels för att det är billigt och dels för att polyester visade sig ha mycket goda egenskaper för de krav som ställdes. Ytterskiktet som är närmast glasfönstret samt innerskiktet in mot rummet valdes till vävar med olika bindningar. Till ytterskiktet jämfördes en tvåskaftsväv med en kypertväv där tvåskaftsväven uppvisade bäst resultat i alla testerna. Kypertväven färgade av sig och nöttes ner i nöthärdighetstestet vilket inte tvåskaftsväven gjorde. Flexibilitets- och reflektionstestet visade goda resultat för båda vävarna. I reflektionstestet pikade tvåskaftsvävens reflektionskurva en aning i det röda spektrat, vilket innebar att den hade en viss röd nyans i sig. Säkerställning av färg gick inte att utföra för de svarta vävarna då svart färg finns i oändligt många olika nyanser. Till det vita innerskiktet jämfördes en tvåskaftsväv med en satinväv. Båda vävarna hade relativt lika resultat i nöthärdighets- samt flexibilitetstestet men satinväven fick bättre resultat i reflektionstestet vilket var avgörande. Vid säkerställning av färg testades den vita färgen i ett ljusskåp i olika ljus för att kontrollera dess vithet. Det visade sig att båda vävarna innehöll optiskt vitmedel vilket även framkom i reflektionstestet då de reflekterade över 100 %. Till mellanskikten jämfördes två olika nonwovenmaterial som består av ihåliga polyesterfibrer. Ihåliga fibrer ha bra ljudabsorption vilket kan vara bra i miljöer såsom skolor och kontor där det kan vara mycket buller och höga ljudnivåer. Det ena materialet vägde 100g/m2 och det andra 250g/m2. Ett nöthärdighets- och flexibilitetstest utfördes på dessa nonwovenmaterial. De båda fick godkänt resultat i flexibilitetstestet men nonwoven 100 höll inte måttet i nöthärdighetstestet varav nonwoven 250 är mest lämpat för rullgardinen. Litteraturstudiens resultat tyder på att det inte finns några krav på flamskyddsmedel i gardiner i offentlig miljö utan endast rekommendationer. Det är alltså upp till företag att bestämma om de vill flamskydda gardinerna. De finns en mängd olika flamskyddsmedelsvarianter men de har alla en sak gemensamt och det är att de är fettlösliga och långlivade, vilket gör att de är svåra att bryta ned. Gardinen designades i en stilren och klassisk design. En kornisch utformades dels för att dölja gardinstången och dels för att erhålla ett snyggare helhetsintryck. Gardinen kommer att ha en fåll längst ned på det yttre och det inre skiktet. Inuti fållen kommer en plastskena läggas för att få tyngd i materialet och därmed ett bättre fall. Fållen ger även gardinen en lyxigare känsla. Resterande kanter på alla materialen för alla skikt valdes att lasras. Med laserskärning erhålls fina kanter som inte fransar sig alls och laserskärning garanterar även att det inte blir någon nötning på produkten under skärningen vilket är fördelaktigt på en rullgardin då den rullas upp och ner mycket. Skisser ritades upp i Kaledo Style för att få en tydligare bild av hur rullgardinen kan komma att se ut. Eventuella tillval, mönster på det vita skiktet samt solceller i olika storlekar, kan även göras på gardinen beroende på kundens önskemål. För att kunna applicera mönstret på det textila materialet undersöktes tre alternativa tryckmönstermetoder; rollerprinting, roterande screentryck samt digital inktryck. De två sistnämnda lämpar sig bäst för ändamålet. / The aim of the thesis was to find the optimal textile materials for a climate-smart blind with multiple layers created by the company Climate Curtains. The aim was also to develop a well thought out design that is adapted to the environments it is supposed to hang in, which are schools and offices. The climate-smart blind should have an absorbing black matte material closest to the glass window to capture UV radiation and thereby become warm. The heat will then be brought into the room with the help of fans that are mounted inside the curtain rod. A solar cell film should also be attached to the layer closest to the window and have therefore been included in the calculations, however, the solar film is still under development. The idea of a solar cell film is first and foremost that it will provide fans with energy but also charging of mobile and computer at the abundance of energy. The blind must also have a white reflective material into the room for the possibility of turning the curtain in the summer. This leads to a reflection of the UV light instead of absorption. Between these two layers, a number of intermediate layers will hang to provide isolation of air and noise reduction. The amount of flame retardants have also been relevant to examine because the curtain will hang in public places. There are no requirements in public places when it comes to flame retardants, but there are recommendations published. A solar cell film should also be attached to the layer closest to the window and have therefore been included in the calculations. However, the solar film is still under development. The work has consisted of literature studies, laboratory work and compilation of discussion and results. The laboratory work included abrasion resistance-, flexibility-, reflection test and a test to secure the colors. The materials studied have all been made of 100% polyester and two alternative materials were chosen for each layer. Polyester was chosen to all layers partly because it is cheap and secondly because polyester was found to have very good qualities for the demands made. The outer layer closest to the window and the inner layer into the room consists of fabrics made of weaves with different constructions. For the outer layer a plain weave and a twill weave were chosen to be compared against each other. The plain weave got the best results in all of the tests. For the inner layer a satin weave and a plain weave were compared, and the satin weave got the best results in all the tests. Furthermore, the layers in between the weave textiles are made of hollow polyester fibers as a nonwoven material. Hollow fibers have good sound absorption, which can be useful in environments such as schools and offices where there may be much noise and high sound levels. One material weighing 100 g/m2 and the other 250 g/m2. An abrasion resistance- and flexibility test was conducted on these nonwoven materials. They both got approved results in the flexibility test. However, nonwoven 100 was not good enough in the abrasion resistance test and therefor nonwoven 250 is the most suitable middle layer for the blind. The curtain was designed in a stylish and classic design. A cornice designed partly to hide the curtain rod and partly to obtain a more attractive overall impression. The blind will have a hem at the bottom of the outer and the inner layer. Inside the hem a plastic splint is added to give better stability. The hem also gives the curtain a luxurious feel. The remaining edges on all materials for all layers were chosen to be lasered. With laser cutting fine edges are obtained.4Sketches were drawn up in Kaledo Style to get a clearer picture of how the blind could look like. Any optional patterns on the white layer and the solar cells of different sizes, can also be made on the curtain, depending on customer requirements. In order to apply the pattern to the textile material three alternative methods was studied; roller printing, rotary screen printing and digital ink print. Screenprinting and digital printing was best suited for the purpose.