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Effect of Multi-support Excitation on the Seismic Behavior of Single-pylon Cable-stayed BridgesSubedi, Arjun 01 December 2014 (has links)
Cable-stayed bridges are popular these days in spite of their complexity in shape and design. Cable-stayed bridges are ideal for a navigational channel due to their high clearance and long central span. These types of bridges also possess advantages over suspension bridges, especially when local site conditions are not suitable for anchoring the towers. In most of the cases, cable-stayed bridges are self-supportive or require less anchorage. Although symmetrical cable-stayed bridges are dominant, asymmetrical bridges are also common as well due to ground layouts and other restrictions like economy, aesthetic purpose. Added counter weight and eccentricity of asymmetrical bridge may highly affect the response of the structure under earthquake loading. For the same length span bridge, the response of the asymmetric one may have an amplified response compared to the symmetric one with the same span length and also, may not follow any predictable trend. This study presents a multi-support analysis for four models, which are, 200 m symmetrical, 400 m symmetrical, 200 m asymmetrical and 400 m asymmetrical bridges. Ground motions has been recorded by using accelerometers. The recorded ground motion depends on the direction of the accelerometer. To remove this dependency, the principal components of each ground motion were found and used for the analysis and the models were excited in the transverse direction. The models were run under both multi-support excitation and identical-support excitation for displacement time-history analysis using SAP2000. Ratio of stresses and deflections were compared for the bridges with the same span length. According to this study, on 200 m asymmetrical bridge, multi-support excitation factored responses up to 4%, while on 400 m asymmetrical bridge, responses are factored up to 20% compared to the identical-support excitation. It is noted that responses of asymmetrical bridges are factored up making identical-support excitation non-conservative.
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Theory of symmetry and asymmetry in two-dimensional magnetic recording headsEdress Mohamed, Ammar Isam January 2016 (has links)
As part of the natural evolution and continued optimisation of their designs, current and future magnetic recording heads, used and proposed in technologies such as perpendicular recording, shingled magnetic recording and two-dimensional magnetic recording, often exhibit asymmetry in their structure. They consist of two semi-infinite poles separated by a gap (where the recording field is produced), with an inner gap faces inclined at an angle. Modelling of the fields from asymmetrical structures is complex, and no explicit solutions are currently available (only implicit conformal mapping solutions are available for rational inclination angles). Moreover, there is limited understanding on the correlation between the gap corner angle and the magnitude, distribution and wavelength response of these head structures. This research was therefore set out to investigate approximate analytical and semi-analytical methods for modelling the magnetic potentials and fields of two-dimensional symmetrical and asymmetrical magnetic recording heads, and deliver a quantitative understanding of the behaviour of the potentials and fields as functions of gap corner angles. The accuracy of the derived expressions (written in terms of the normalised root-mean-square deviation) was assessed by comparison to exact available solutions for limited cases, and to finite-element calculations on Comsol Multiphysics. Two analytical methods were derived to approximately model the fields from two-dimensional heads with tilted gap corners in the presence and absence of a soft magnetic underlayer (SUL): in the first method, the potential near a single, two-dimensional corner held at a constant potential is derived exactly through solution of Laplace's equation for the scalar potential in polar coordinates. Then through appropriate choice of enclosing boundary conditions, the potentials and fields of two corners at equal and opposite potentials and displaced from each other by a distance equal to the gap length were superposed to map the potential and field for asymmetrical and symmetrical heads. For asymmetrical heads, the superposition approximation provided good agreement to finite-element calculations for the limited range of exterior corner angles 0 from 0 (right-angled corner) to 45, due to the mismatch of surface charge densities on both poles for this geometry. For symmetrical head structures, the superposition approximation was found to yield remarkable agreement to exact solutions for all gap corner orientations from 0 (right-angled head) to 90 ("thin" gap head). In the second method derived in this research for modelling asymmetrical heads involved using a rational function approximation with free parameters to model the surface potential of asymmetrical heads. The free parameters and their functional dependence on corner angle were determined through fitting to finite-element calculations, enabling the derivation of analytical expressions for the magnetic fields that are in good agreement with exact solutions for all corner angels (0 to 90). To complement the two approximate methods for modelling the fields from asymmetrical and symmetrical heads, a new general approach based on the sine integral transform was derived to model the reaction of soft underlayers on the surface potential or field of any two-dimensional head structure, for sufficiently close head-to-underlayer separations. This method produces an infinite series of correction terms whose coefficients are functions of the head-to-underlayer separation and gap corner angle, that are added to the surface potential or field in the absence of an underlayer. This new approach demonstrated good agreement with finite-element calculations for sufficiently close head-to-underlayer separations, and with the classical Green's functions solutions for increasing separations. Using the derived analytical method and explicit expressions in this work, an understanding of the nature of the magnetic fields and their spectra as functions of the gap corner angles is gained. This understanding and analytical theory will benefit the modelling, design and optimisation of high performance magnetic recording heads.
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För mycket transparens? : En kvalitativ studie gällande införandet av Markets in Financial Instruments II och bankaktörers upplevda påverkanWener, Louise, Mardini, Maria January 2019 (has links)
Denna studie har genomförts i syfte att undersöka påverkan på svenska banker under och efter införandet av direktivet Market in Financial Instruments Directive (MiFID) IIs transparenskrav. Efter reguljära brister på den finansiella marknaden utformades det nya direktivet för att stärka transparensen för samtliga aktörer. Problematiken finns i eventuella risker som uppstår vid ökat krav på transparens och hur bankerna hanterar dessa samt hur den asymmetriska informationen påverkas på marknaden mellan konsument och företag. Studien är av kvalitativ art och den primära källan består av intervjuer med utvalda aktörer på den svenska bankmarknaden. Resultatet visade att respondenterna ansåg att en gräns för öppenhet inte existerar och att transparens därmed inte kan bli för hög. Med de nya transparenskraven sågs en positiv effekt på marknadskvaliteten då ökade krav lett till högre disciplin och därmed minskad asymmetrisk information. Dock bekräftas teorin som menar att allmänheten kan översvämmas med för mycket information som i sin tur skapar osäkerhet hos konsumenten. Studien visade att majoriteten av respondenterna ansåg sig vara positiva över de förhöjda transparenskraven och ser stora möjligheter trots konstaterade risker. / This study was carried out with the aim of investigating the impact on Swedish banks during and after the introduction of the directive Market in financial instruments (MiFID) II transparency requirements. After regular shortcomings in the financial market, the new directive was designed to strengthen the transparency for all actors. The problem is the possible risks arising from increased transparency requirements and how banks act and how the asymmetric information is affected on the market between consumers and companies. The study is of qualitative art and the primary source consists of interviews with selected actors in the Swedish banking market. The result showed that respondents felt that a limit of transparency does not exist and that transparency can not be too much. With the new transparency directive, a positive effect on market quality was seen as increased demands led to higher discipline and thereby reduced asymmetric information.However, the theory confirms that the public can be flooded with too much information, which in turn creates uncertainty for the consumer. Studies showed that the majority of respondents felt positive about the increased transparency requirements and saw great opportunities even though risks were found.
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Krympande kommuners möjligheter till klimatanpassning : En studie om resursprioriteringarIsberg, Simon, Stafverfeldt, Maria January 2020 (has links)
Krympande kommuner har ett begränsat skatteunderlag som innebär att de måste göra prioriteringar mellan olika intressen. Syftet med denna uppsats är därmed att undersöka vilka förutsättningar krympande kommuner har att genomföra klimatanpassningsarbete för att förstå hur de prioriterar sina resurser. Uppsatsen baseras primärt på en intervjustudie där vi har genomfört intervjuer med personer från Valdemarsviks och Ydre kommun, Länsstyrelsen Östergötland och SMHI. Vi utgick huvudsakligen från de teoretiska begreppen; tillväxtnorm, klimatanpassningsbehov, resurskoordinering och asymmetrisk ansvarsfördelning. Vi diskuterar hur det är ett problem att kommunerna har samma uppdrag men olika förutsättningar att genomföra dessa där det inte finns något system för att hantera denna skillnad. Vi presenterar asymmetrisk ansvarsfördelning som en potentiell lösning på detta problem. Vår främsta slutsats är hur kommunernas existensberättigande måste prioriteras framför satsningar inom klimatanpassning. / Due to shrinking municipalities having fewer resources they have to prioritise between interests. The aim of this thesis is to explore what opportunities shrinking municipalities have to implement climate adaptation in order to understand their resource prioritisation.We have conducted interviews with Valdemarsviks and Ydre municipality, Länsstyrelsen Östergötland, and SMHI. This study is based on the theoretical concepts; ‘growth norm’, ‘need for climate adaptation’, ‘resource coordination’, and ‘asymmetrical allocation of responsibilities’. We discuss the problem of municipalities having the same responsibilities but different amounts of resources to execute them. Together with a lack of system to manage this difference this creates a problem. We present asymmetrical allocation of responsibilities as a solution to this problem. Our main conclusions refer to municipalities’ strive to sustain a justification for their existence which leads to them prioritising this over climate adaptation.
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Identifying and Evaluating Common Subgenres in Asymmetric Virtual Reality GamesDawes, Miah 16 December 2021 (has links)
Recent years have seen a significant growth in what designers and players call asymmetric virtual reality (AVR) games. This dissertation creates a framework that defines the relevant characteristics of AVR as a genre and describes five common genres of AVR games, including David(s) and Goliath, Hide and Seek, Perspective Puzzle, Order Simulation, and Lifeline. The core features of each subgenre are expounded. These subgenres are then evaluated using design workshops to observe novice game designs use these subgenres in their game design process. An analysis of the workshops found that the AVR subgenre framework may benefit novice game designers in finding inspiration from patterns in existing AVR games, planning asymmetric mechanics in AVR games between VR and non-VR players, and concepting new and unexplored ideas within the AVR genre. Finally, the discussion section outlines similarities and differences in the subgenres, limitations in this research, and provides guidance for future directions for this research.
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Microscopic study of the behavior of water in a single pore under vibration to intensify drying / Étude microscopique du comportement de l'eau dans un pore unique soumis à des vibrations pour intensifier le séchageChen, Wangshu 02 July 2019 (has links)
Une meilleure performance économique du séchage industriel consiste à la fois en l'amélioration de la qualité des produits et de l’optimisation énergétique. Plusieurs technologies peuvent être appliquées pour intensifier le processus de séchage. Ce travail s’intéresse à l'effet des vibrations, qui peuvent accélérer le séchage via un échauffement par dissipation visqueuse, une amélioration de la migration de l’eau liquide et de la vapeur à l'intérieur du milieu poreux et une augmentation des coefficients de transferts externes de chaleur de masse. Toutefois, malgré les études numériques et expérimentales antérieures, l'évaluation de l'importance relative de ces mécanismes d'intensification doit encore être améliorée.Ce travail porte sur l'échelle du pore, simulée par un tube capillaire, partiellement rempli d'eau soumis à des vibrations sinusoïdales. Un dispositif expérimental complet a été conçu, développé et utilisé. Grâce à une procédure de traitement d'images pertinente, le comportement de l'eau à l'intérieur du tube (déplacement et le rayon du ménisque) ont été étudiés pour différentes configurations de vibrations (fréquence, amplitude, taille du tube). Les expériences avec des géométries symétriques et asymétriques sont destinées à imiter le transfert d'humidité pendant le séchage d'un milieu poreux. Quelle que soit la configuration étudiée, l'intensification du séchage a été clairement confirmée.Pour la configuration symétrique, une nouvelle cartographie 2D basée sur des nombres adimensionnels est définie pour résumer les effets capillaires et visqueux, et ainsi expliquer le comportement de l'eau en fonction des conditions vibratoires (rayon du tube, fréquence et amplitude). Pour la configuration asymétrique, les résultats expérimentaux sont discutés et comparés aux simulations obtenues avec deux modèles numériques (un modèle 0-D et un modèle 1-D). Le potentiel de la modélisation a été mis en évidence, mais il est encore limité par les hypothèses physiques aux interfaces. D'autres développements sont proposés afin d'augmenter la plage de validité et d'approfondir l'étude de ce système physique. / A better economic performance of industrial drying consists both in product quality improvement and energy efficiency enhancement. Several technologies can be applied to intensify the drying process. This work is focused on the effect of vibration that can assist the drying through heating-up due to viscous dissipation, enhancement of liquid and vapor migration inside the porous medium and the increase of the external heat and mass transfer. However, despite previous numerical and experimental studies, the assessment of the relative importance of these intensification mechanisms has still to be improved.This work is focused on the pore scale, simulated by a capillary tube, partially filled with water subjected to sinusoidal vibrations. A full experimental device was conceived, developed and used. Thanks to a relevant image processing chain, the behavior of water inside the tube (displacement and meniscus radius), was investigated for various vibration configurations (frequency, amplitude, tube size). Experiments with both symmetrical and asymmetrical geometries are intended to mimic the moisture transfer during drying of a porous medium. Whatever the configuration, the drying intensification was clearly confirmed.For the symmetrical configuration, a new 2D dimensionless number map is set to summarize the capillary and viscous effects and thus to explain the water behavior depending on vibration conditions (tube radius, frequency and amplitude). For the asymmetrical configuration, the experimental results are discussed and compared to the simulations obtained with two computational models (a 0-D model and 1-D model). The potential of modeling was evidenced but still limited by the surrounding physical assumptions. Further developments are proposed to increase the validity range and further investigate this physical system
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Asymmetrische Ausblicke: Ruhige Ausschnitte versus dynamische FormEsslinger, Alexander, Evers, Tanja 17 November 2023 (has links)
Der Entwurf beschäftigt sich mit der Transformation einer Fläche zur Form. Durch das Stilmittel der Faltung werden zweidimensionale Flächen in ein dreidimensionales Objekt überführt. Dieser konstruktive Wandel, durch den aktiven Eingriff des Menschen, stellt ein positives Zukunftsmodell da. Es entsteht ein horizontal ausgerichteter Raum, der eine dynamische Formensprache in der Außenwirkung aufweist. Im spannenden Gegensatz dazu stehen die ruhig ausgerichteten, konzentrierten Innenansichten mit Blick auf den Bildausschnitt – die Natur.
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New multi-standard dual-wideband and quad-wideband asymmetric step impedance resonator filters with wide stop band restrictionAl-Yasir, Yasir I.A., Tu, Yuxiang X., Ojaroudi Parchin, Naser, Abdulkhaleq, Ahmed M., Kosha , Jamal S.M., Ullah, Atta, Abd-Alhameed, Raed, Noras, James M. 28 September 2023 (has links)
Yes / New multi-standard wide band filters with compact sizes are designed for wireless communication devices. The proposed structures realize dual-wideband and quad-wideband characteristics by using a new skew-symmetrical coupled pair of asymmetric stepped impedance resonators, combined with other structures. The first and second dual-wideband filters realize fractional bandwidths (FBW) of 43.2%/31.9% at the central frequencies (CF) of 1.875/1.63 GHz, and second bandwidths of 580 MHz/1.75 GHz at CF of 5.52/4.46 GHz, respectively. The proposed quad-band filter realizes its first/second/third/fourth pass bands at CF 2.13/5.25/7.685/9.31 GHz with FBW of 46.0%/11.4%/4.6%and 5.4%, respectively. The wide pass bands are attributed to the mutual coupling of the modified ASIR resonators and their bandwidths are controllable by tuning relative parameters while the wide stop band performance is optimized by the novel interdigital cross coupled line structure and parallel uncoupled microstrip line structure. Moreover, the quad band is generated by introducing the novel defected rectangle structure. These multi-standard filters are simulated, fabricated and measured, and measured results agree well with both simulated results and theory predictions. The good in-band and out-of-band performances, the miniaturized sizes and simple structures of the proposed filters make them very promising for applications in future multi-standard wireless communication. / Horizon 2020 Framework Programme(European Union), Grant/Award Number:H2020-MSCA-ITN-2016 SECRET-722 424
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Asymmetrical S-band coupled resonator filtersCoetzee, Nicola 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / Due to a more densely packed frequency spectrum, there is an increasing demand for
narrow band filters with asymmetrical transfer function characteristics. The resulting
coupling matrices contain both positive and negative couplings, cross couplings and individual
resonator frequency offsets.
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Improved performance characteristics of induction machines with non-skewed symmetrical rotor slotsChitroju, Rathna January 2009 (has links)
<p>Induction machines convert more than 55% of electrical energy into various other forms in industrial and domestic environments. Improved performance, especially by reduction of losses in induction machines hence can significantly reduce consumption of electricity. Many design and control methods are adopted to make induction machines work more efficiently, however certain design compromises are inevitable, such as skewing the rotor to improve the magnetic noise and torque characteristics increase the cross current losses considerably in a cage rotor, degrading the efficiency of the motor. Crosscurrent losses are the dominating stray losses which are dependent on several factors among them are percentage skew and the contact resistance between the rotor bars and laminations. It is shown in this thesis that implementing a design change which has non-skewed asymmetrical distribution of rotor slots can serve the same purpose as skewing i.e., reduction of the magnetic noise, thereby avoiding the negative effects of skewing the rotor slots especially by reducing the cross-current losses.</p><p>Two design ethodologies to introduce asymmetry in rotor slots are proposed and the key performance characteristics like torque ripple, radial air gap forces are computed both numerically and analytically. Radial forces obtained from the finite element method are coupled to the analytical tool forcalculating the magnetic noise. A spectral method to calculate and separate the radial forces into vibration modes and their respective frequencies is proposed and validated for a standard 4-pole induction motor. The influence of rotor slot number, eccentricity and skew on radial forces and magnetic noise are studied using finite element method in order to understand the vibrational and acoustic behavior of the machine, especially for identifying their sources. The validated methods on standard motors are applied for investigating the asymmetrical rotor slot machines.</p><p>Radial air gap forces and magnetic noise spectra are computed for the novel dual and sinusoidal symmetrical rotors and compared with the standard symmetrical rotor. The results obtained showed reduced radial forces and magnetic noise in asymmetrical rotors, both for the eccentric and noneccentric cases. Based on the results obtained some guide lines for designing asymmetrical rotor slots are established. Magnitudes of the harmful modes of vibration observed in the eccentric rotors, which usually occur in reality, are considerably reduced in asymmetrical rotors showing lower sound intensity levels produced by asymmetrical rotors. The noise level from mode-2 vibration in a 4-pole standard 15 kW motor running with 25% static eccentricity is decreased by about 6 dB, compared to the standard rotors. Hence improved performance can be achieved by removing skew which reduces cross current losses and by employing asymmetrical rotor slots same noise level can be maintained or can be even lowered.</p><p> </p><p> </p>
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