A new variation of the spherical helical antenna made of a wire wound over a hemispherical surface and backed by a conducting ground plane is introduced. A constant spacing is maintained between the turns of winding. The geometry of this antenna is fully described by the number of turns and the radius of hemispherical surface. In addition to the hemispherical geometry, truncated double spherical helices are also examined. Radiation properties of the proposed antennas are studied both theoretically and experimentally. The wire antenna code ESP (electromagnetic surface patch), which is based on the method of moments, is used to obtain simulation results. The results for far-field patterns, gain, axial ratio, bandwidth, and input impedance are presented. Several prototypes of this antenna were constructed and tested using an outdoor antenna range. Far-field patterns were measured over a wide range of frequencies. The measured and calculated radiation patterns are in good agreement. A unique property of the hemispherical helix is its broad half-power beamwidth. Furthermore, this antenna provides circular polarization and relatively high gain over a narrow frequency range. The results of this research show that, for example, a 4.5-turn hemispherical helix with a radius of 0.02 meter designed for operation around 2.8 GHz provides a half-power beamwidth of about 90 degrees, more than 9 dB gain, and less than 3 dB axial ratio over a 300 MHz bandwidth. The input impedance of the antenna is largely resistive and is about 150 ohms in the above frequency range. Compared with a full spherical helix, the hemispherical helix provides comparable radiation characteristics, but occupies only half the volume. The compact size of this antenna makes it attractive to mobile communication applications / Master of Science

No description available.

Under der senaste år-tiondet har 'X-by-wire' teknologier stadigt introducerats inom kommersiellbiltilverkning. Detta har hänt på grund av de otaliga fördelar dessa teknologier har över derasmekaniska motparter. Huvudskillnaden är att man använder sig av elektro-mekaniska system iställetfor mekaniska förbindelser. I ett 'throttle-by-wire' system till exempel blir positionen av gaspedalenkontrollerad av sensorer och den elektriska aktuatorn föryttar strypan följaktligen. Fördelen är attinformationen som samlas av andra sensorer även kan påverka på hur strypan öppnas. Detta gerextra flexibilitet till mekanismen. Det nästa system bil-manufaktorer vill anpassa till 'by-wire'-systemär bromsarna. Principen här är att flytta bromspedalerna med en elektrisk motor som är placeradi kaliperna och därmed helt byta ut kolvarna och den hydraulkretsen som just nu används för attåstadkomma detta. Att genomföra detta är mödosamt då bromsning ar kritiskt för säkerheten ochdärmed måste fullt följa strikta regulationer. Man måste fortfarande kunna bromsa om strömmen intefungerar i huvudströmkretsen. Biltillverkare har därför undersökt olika backup-system for att kringgådetta problem. Alla möjligheter har sina nackdelar och förvecklar designen en hel del. Detta arbeteutforskar en ny 'brake-by-wire'-design som är härledd från studier av andra undersökta system. Måletav det nya konceptet är att lösa några av de uppmärksammade problem i andra design. Dokumentetbörjar genom att granska redan existerande 'brake-by-wire' teknologier och beskriver deras för-och nackdelar.Vidare kommer det nya konceptet beskrivas med de förbundna fördelarna. Efter det byggsen simulationsmodell for att ta reda på om ideen är möjlig att bygga och skulle fungera. Sedan ritasen CAD-modell av monteringen och ett flertal FEM-studier genomförs för att utvärdera styrkorna avnågra kritiska komponenter. Till slut förfinas modellen och de erhållna resultaten diskuteras. Dessaanvänds för att kritiskt kommentera koncepten och för att ge rekommendationer for möjlig framtidautveckling. / In the last decades or so, \X-by-wire" technologies have been steadily introduced in commercial carsfor the numerous advantages they provide over their mechanical counterparts. The core principleconsists of using electro-mechanical systems instead of mechanical linkages. In a throttle-by-wiresystem for instance, the position of the gas pedal is monitored by a bunch of sensors while an electricactuator moves the throttle accordingly. The advantage is that data gathered by other sensors mayalso inuence the throttle opening, giving extra exibility to the mechanism.The next system automobile manufacturers want to adapt to \by-wire" is the brake. The principleis to move the braking pads with an electric motor located in the calipers and to get completely ridof the pistons and hydraulic circuit currently used to this eect in cars. Nonetheless, the transition isarduous because braking is safety critical and must therefore comply with strict regulations. Indeed,it must still be possible to apply the brakes in case of a power loss on the main electric circuit.Manufacturers have therefore been exploring dierent backup systems to circumvent the issue butthey all present downsides and complicate the design to a great extent.This work studies a new brake-by-wire design whose concept was derived from the study of theother systems presently investigated. The aim of this new concept is to resolve some of the issuesobserved in other designs.This document starts by reviewing the existing brake-by-wire technologies and describing their prosand cons. Next, the new concept is described along with the advantages it may bring. Subsequently,a simulation model is built to assess whether the idea is plausible and can function properly. Later, aCAD model of the assembly is drawn and various FEM studies are conducted to evaluate the strengthof some critical components. Finally, the simulation model is rened and the results obtained arediscussed and used to comment critically the concept and give recommendations for possible futuredevelopments.

Yes / The current paper presents a simple unbonded-type column strengthening technique with wire rope units and few steel elements. Eleven short columns were strengthened using the proposed procedure and tested under monotonic concentric axial loads. The main variables investigated to evaluate the confinement effectiveness of strengthened concrete columns were the volume ratio, prestress, diameter, spacing and configuration of wire rope units. The strength gain factor and ductility ratio increased with the increase of volume ratio of wire ropes. The prestress applied to wire ropes had little influence on the strength gain factor but the ductility ratio decreased with the increase of prestress in the wire ropes, owing to earlier rupture of wire ropes. At the same volume ratio of wire ropes, the maximum strength of columns was nearly independent on the configuration of the wire ropes, but higher ductility was exhibited by columns strengthened with rectangular spiral-type wire ropes than by columns strengthened with hoop-type wire ropes, until rupture of the wire ropes. The strength gain factor and ductility ratio of strengthened columns were compared with those of tied columns tested in a previous study. The load capacity of strengthened columns was also predicted using the ACI 318-05 equation modified to reflect the load-carrying effect of steel elements. A much higher strength gain factor and ductility ratio were exhibited by strengthened columns than tied columns having the same lateral reinforcement, except for strengthened columns with wire rope spacing above 0.5 times core width. The axial load capacity of strengthened columns was higher than that of unstrengthened columns by 5¿20%, and could be reasonably predicted using the modified ACI 318-05 equation.

Yes / Fretting wear has a significant influence on wire rope fatigue life when in cyclic bending, particularly for crossed-wire contacts, where the interfacial motion of the surfaces is complex and multi-axial. To simulate these contacts in a controlled manner, a laboratory-scale, crossed-cylinder, reciprocating fretting wear test was developed. A broad range of contemporary lubrication technologies were evaluated using this method and a systematic multivariate statistical analysis was performed to identify the most significant lubrication-related parameters with respect to these fretting wear conditions. Wear area increase per slip cycle was the most relevant measure of wear damage, as this captured the influence of changes in the fretting wear regime during the test. The ability of a lubricant to reduce damaging fretting wear during the run-in phase was the biggest influence on long-term fretting wear, particularly for grease-lubricated contacts.

<p> An experimental study of forced convection heat transfer and friction in water flowing in a vertical tube is reported in this thesis. The study investigates the effect of coiled wire turbulence promotors of various pitch to diameter ratios (ranging from 1.00 to 5.50) upon the Nusselt Prandtl modulus Nu/Pr^1/3 and Fanning friction factor f. The investigation is carried out for three different wire sizes, 0.052 in., 0.063 in., 0.072 in. respectively.</p> <p> Analysis of the various dimensionless numbers computed from the measurements of the present study indicates that the heat transfer increases by as much as 250% for low values of pitch to diameter ratio, though at the cost of a much larger increase in pressure drop. Consequently, the tubes using coiled wire turbulence promotors can be employed with advantage for cases where pumping power is not the dominating factor and reduction in weight and size of the equipment are more important.</p> <p> The experimental data are empirically correlated in terms of the ratio of Nusselt numbers for the tubes with turbulence promoters to the empty tube as a function of Reynolds number and pitch to diameter ratio. Nu/Nuo = K(Re)^a (H/D)^-0.3 </p> <p> To evaluate the net effect of coiled wire turbulence promotors, the ratio j/f = [Nu/RePr^1/3]/f is plotted against Reynolds number. The curves for the coiled wire turbulence promotors fell below the theoretical curve for the empty tube indicating that coiled wire turbulence promotors are not advantageous in terms of heat transfer per unit pressure drop.</p> / Thesis / Master of Engineering (MEngr)

No description available.

Experiments were performed to document the turbulent flowfield produced downstream of an airfoil encountering an intense streamwise vortex. This type of perpendicular airfoil--vortex interaction commonly occurs in helicopter rotor flows. The experiments presented here thus provide useful information for the prediction of helicopter noise, particularly BWI noise. Three-component velocity and turbulence measurements were made in unprecedented detail using a computerized miniature four-sensor hot-wire probe system; revealing much about the structure and behavior of this flow over a range of conditions. The interaction between the vortex and the airfoil wake leaves the vortex surrounded by a large region of intense turbulence unlike the turbulence surrounding an isolated vortex. Even for close separations, the vortex core passes the airfoil virtually unchanged. However, vorticity of opposite sign is shed by the airfoil in response to the angle of attack distribution induced by the vortex resulting in an unstable circulation distribution according to Rayleigh's criterion. Simple theoretical models adequately describe the shed vorticity distribution of the airfoil and the unstable circulation distribution it imparts on the vortex. As the flow develops, the vortex continuously distorts the airfoil wake. The strain rates imparted by the vortex on the spanwise vorticity contained in the airfoil wake result in an anisotropic, turbulence producing stress field. For several chord lengths downstream, the vortex core remains laminar and little change is seen in the unstable circulation distribution. While the vortex core is laminar, turbulent fluctuations measured in the core are the result of inactive wandering motions and the characteristic length and velocity scales of the flat portion of the vortex wake appear to be appropriate scales for the fluctuations. Eventually, the vortex core becomes turbulent as indicated by an increase in high frequency velocity fluctuation levels of more than an order of magnitude. Subsequently, the circulation distribution reorganizes to a stable distribution. A loss in core circulation occurs due to a decrease in the peak tangential velocity which is proportionately larger than the increase in the vortex core radius. The peak tangential velocity decreases to the point where it is exceeded by the axial velocity deficit---another unstable situation. These effects increase with decreased separation between the vortex and the airfoil, but appear to be largely independent of airfoil angle of attack an only weakly dependent upon vortex strength. / Ph. D.

This study has taken place in Mullsjö at Kongsberg Automotive (KA). The purpose of the study was to evaluate how to construct an easy mountable gearknob to the lowest cost based on design and functionality by using the techniques of concept generation and sifting. The knob is intended to be integrated in a Shift-ByWire shifter and generate prototypes through SLS. Researchers followed a concept study methodology following an abductive approach, to generate an appropriate mechanical design for the gearknob. Concepts were formed by a brainstorming process, followed by weighing criteria for the knob and were finalised by evaluating the formed concepts using a Pughs Matrix constructed by the researches. Relevant literature of mechanical designs processes was reviewed to develop the theoretical framework. In addition, data was collected from Kongsberg´s computer system and unstructured interviews with employees within certain specific areas to gain additional understanding. In cooperation with supervisors, pros and cons analysis of cost, functionality and mounting capability were used to enable the researchers to draw recommendations for mechanical designs meeting the requirements of specification. The study resulted in several findings in relation to each research question. In general, a gear knob has been constructed using SLS that can be both used for mounting and demounting purposes. In addition, this construction met the specification of requirements by KA. The Printed Circuit Board (PCB) were constructed using the geometrics in the inherent components of the knob. The study further resulted in a leather gaiter that were constructed as a link between the dashboard and the knob. Results from this study imply that more screws would be used for mounting different components in the prototype phase, which will impact the view on criteria for forthcoming knobs and their mounting methods. In addition, data collection have also shown that snaps in chromium details easily break, which can also further question the use of chromium snaps for dismantling purposes. Finalised recommendations for the gearknob met the requirements of specification since researchers constructed the most simple mounting on the current surface design. Researchers conclude that these concepts are applicable and could be presented in a following prototype phase. However, if the knob is to be produced, researchers do not have enough support regarding the liquid injection moulding, which requires to be further considered. Materials will require the design constructed in this study to be modified. / Arbetet har skett i Mullsjö på Kongsberg Automotive (KA). Syftet med studien var att konstruera en lättmonterad växelspaksknopp till lägsta kostnad utifrån design och funktionalitet. Detta baserat på konceptgenerering och sållningstekniker. Knoppen kommer att integreras i en Shift-by-Wire växelspak och tillverkas i SLS prototyper. Arbetet är en konceptstudie som har följt en abduktiv ansats. Tidigare konstruktionslösningar har studerats för att få kunskap om hur en knopp utformas. Koncepten har genererats via brainstorming och har följts upp av parvis viktning. Koncepten har sedan sållats med hjälp av Pughs matris. Relevant litteratur inom produktutvecklingsprocesser samt intervjuer med anställda har gett grunden till det teoretiska ramverket. Handledare har givit sin input under hela arbetsprocessen för att hjälpa studenterna att välja rätt koncept utifrån monterbarhet, funktionalitet och pris. Studien har svarat på de tre frågeställningarna som utformats. En knopp i SLS har konstruerats utifrån enkel montering och demontering som möter företagets kravspecifikation. Kretskorten inuti knoppen har formats utefter de ingående delarnas geometrier. Vidare har övergången mellan knopp och centerkonsol resulterat i en läderdamask. Studiens resultat kan få konsekvenser i att mer skruv kommer att användas i prototypfasen vid framtida projekt. Detta kan komma att ändra synen på hur viktigt monterbarheten kan vara i kommande knoppar. Informationsinsamling har också visat att snäppen i kromdetaljer lätt går av och detta kan ifrågasätta användningen av dessa. Vid materialval rekommenderas det att se över konstruktionslösningarna då de uppnådda egenskaperna kan avvika. Arbetet har utformat konstruktionen så att det fungerar bra för SLS prototyper men studenterna kan inte garantera att dessa fungerar om komponenterna ska formsprutas.

Este trabalho analisa a série televisiva The Wire (EUA, 2002-2008) como forma de investigar os conceitos psicanalíticos de sublimação e realidade. The Wire toma como ponto de partida o tráfico de drogas em Baltimore, nos Estados Unidos, para examinar o funcionamento de diversas instituições da cidade: polícia, sindicato de estivadores, prefeitura, escola e imprensa. Primeiramente, situamos The Wire no contexto das séries televisivas norte-americanas e consideramos sua estrutura formal e aspectos narrativos e visuais. Em seguida, procedemos a uma narrativa comentada das cinco temporadas da série, atentando para os modos de organização do tráfico de drogas em cada uma delas. O capítulo seguinte consiste em uma investigação dos conceitos de sublimação e realidade na obra freudiana, dividida em três seções: a constituição do aparelho psíquico, as pulsões e seus destinos e o mal-estar na cultura. Por fim, relacionamos as duas investigações realizadas anteriormente, chegando à noção de uma sublimação que está a serviço de Tânatos, ou seja, da destruição. O alvo dessa destruição, nas sociedades capitalistas atuais, é o corpo humano e o corpo da Terra a natureza, entendida como recurso infinito a ser explorado. Essa sublimação, em que a pulsão de morte associa-se à de dominação, levou-nos a considerar a realidade a partir de um eixo pulsional: há realidades eróticas e realidades tanáticas / This work looks at television show The Wire (USA, 2002-2008) as a means to investigate the psychoanalytic concepts of sublimation and reality. The Wire takes drug trafficking in Baltimore as a starting point to consider the institutions of the police, the stevedores union, the city government, city schools and the press. This dissertation first situates The Wire within the context of US television and considers its formal structure and visual and narrative aspects. It then proceeds to describe and comment on the five seasons of the show, paying special attention to the modus operandi of drug trafficking in each of them. The following chapter is an investigation of the concepts of sublimation and reality throughout Freuds writings, divided into three sections: the constitution of the psychic apparatus, the drives and their vicissitudes and the civilization and its discontents. Lastly, this work connects the studies of The Wire and Freud conducted in previous chapters and advances the notion of a type of sublimation which is at the service of Thanatos, i.e., destruction. The target of such destruction in current capitalist societies is the body of humans and the body of the Earth namely nature, understood as an array of infinite resources to be exploited. This sublimation, in which the death drive is fused with the domination drive, has prompted the consideration of reality from a drive perspective: there are both erotic and thanatic realities