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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.
101

Optimalizace přímého pohonu posuvové osy pomocí hltiče vibrací / Optimization of the direct feed drive by the vibration damper

Hradil, Jan January 2011 (has links)
This diploma thesis deals with the application of three methods to limit resonances of critical frequencies and with a description of their influence on speed control loop of linear drive. The first damping method involved the use of an electro-magnetic tilger attached to the structure of stand on critical locations. The second method involved the use of a jerk decoupling in linear direct drives. A Cauer-filter that was activated in the controller of linear motor was added to both methods. The appropriate measuring technique for these frequencies was systematically analysed and selected. Further in this document models of mechanical structure and controlling are described. Matlab®/Simulink® software was used for the data processing and the modification of models according to the real structure.
102

Causes of Audit Delay and their Effects on Public Sector Audit Quality : (a case of the Supreme Audit Institution of Liberia - General Auditing Commission)

Fully, Richard Baros, David, Kortu Duke January 2020 (has links)
Audit delay refers to the time from the end of the country or company’s financial year to the date of the audit report. The chances of delay of audit in the public sector are pervasive and as such the expectations of users of these audit reports may differ which could result in the quality and reliability of these audits within this sector to be questioned. Accordingly, the purpose of this study is to explore the external and internal factors that cause audit delay and the aftermath they have on public sector audit quality. As for this study, its original value correlates with the espousal of the institutional theory from the perspective of public sector auditing. Considering the aim of this study, a qualitative research was preferred with the objective of gathering in-depth and enriched empirical data; hence, semi structured interviews were conducted with ten auditors of the top and middle management of the Supreme Audit Institution (SAI) of Liberia – General Auditing Commission. There are varying views regarding the findings of this study as the respondents disclose that the external factors that result to audit delays are caused by either the audited entity or other external parties and not the SAI; however, it is the responsibility of the SAI to work with the entity involved to ensure those factors do not impede the audit process to the extent it cannot be completed; whereas, internal factors which includes inadequate staff training, delay in the review and approval of the draft audit report by top management to the poor performance of auditors as a result of lack of knowledge and etcetera cause audit delays as well and the SAI is solely responsible for ensuring that they are resolved or lessened so as not to affect the timeliness of the reporting process. The study mentions several limitations. One of them is the lack of observation being conducted which would have provided first-hand information on factors that cause the delay of audits in the public sector.
103

The decoupling process of CO2 emissions and economic growth : A comparative study between the European Union and middle income countries in South and East Asia / Frikopplingsprocessen av CO2 utsläpp och ekonomisk tillväxt : En jämförande studie av den Europeiska Unionen och medelinkomstländer i södra och östra Asien

Alverhed, Elin, Kåvik, Frida January 2020 (has links)
This paper compares and analyzes the decoupling processes of carbon emissions to economic growth in the European Union and South and East Asian middle income countries. This is done through econometric methods, testing for a relationship between CO2 and GDP. The study is conducted by first testing for the hypothesis that there is a significant difference of the turning points between the EU and the Asian region, and thereafter if there is a significant difference in the decoupling processes. The findings show that the Asian middle income countries have a lower turning point than the EU. It is also found that the EU experienced absolute decoupling in 2014, whereas the Asian countries only experienced weak relative decoupling. The study is based on four theories; The Environmental Kuznets curve, Tapio’s Decoupling model Theory, Rostow’s Stage of Growth Theory and the Ecological Modernization Theory. The findings, together with the theories, show that improved technology, together with implementations of international policies, can have positive effects on environmental changes.
104

Acceleration sensitivity study on coupled resonators for designing anti-shock tuning fork gyroscopes / 耐衝撃性を有する音叉型ジャイロスコープ設計のための結合共振子の加速度感度に関する研究

Praveen Singh Thakur 24 September 2014 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18588号 / 工博第3949号 / 新制||工||1607(附属図書館) / 31488 / 京都大学大学院工学研究科マイクロエンジニアリング専攻 / (主査)教授 田畑 修, 教授 西脇 眞二, 准教授 土屋 智由, 教授 引原 隆士 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
105

Tunneling Spectroscopy Studies of Superconductors

Oli, Basu Dev January 2021 (has links)
In multiband superconductors, different bands at the Fermi surface contribute to the superconductivity with different magnitudes of superconducting gaps on different portions of the Fermi surface. Each band in a multiband superconductor has a condensate with an amplitude and phase that weakly interacts with the other bands’ condensate. The coupling strength between the bands determines whether one or two superconducting transition temperatures are observed, and it is the key to many peculiar properties. In general, if there are two gaps of different magnitude, there are two different length scales associated with the suppression of these gaps in applied magnetic fields, for example. Therefore, effects of multigap superconductivity can be observed in superconducting vortices, which are twirls of supercurrents that are generated when a superconductor is placed in a magnetic field. Furthermore, the two superconducting order parameters in different bands are characterized by a magnitude and phase. In multiband superconductors, there are collective excitations corresponding to fluctuations of the relative phase of two order parameters, so-called the Leggett mode. The first material identified as multiband superconductor is Magnesium Diboride (MgB2) in 2001 with a critical temperature Tc of 39 K. MgB2 is a superconducting material with the highest transition temperature among all conventional BCS superconductors. It has two superconducting gaps \Delta_\pi ~ 2 meV and \Delta_\sigma\ ~ 7 meV and they arise from the existence of two bands \pi and \sigma bands of boron electrons. The discovery of superconductivity in MgB2 renewed interest in the field of multiband superconductivity. MgB2 has attracted many scientists’ attention both for the fundamental importance of understanding the multiband superconductivity and possible applications such as magnets, power cables, bolometers, Josephson junction-based electronic devices, and radio-frequency cavities. Afterward, other materials have been identified as multiband superconductors such as NbSe2, the family of iron-based superconductors, heavy fermion superconductors, multilayer cuprates, borocarbides, etc. This dissertation uses tunneling experiments to highlight multiband superconductivity features in two systems, namely MgB2 thin films and ultrathin films of Pb. Further, we use multiple techniques to study a superconducting material, nitrogen-doped niobium, used for superconducting radio-frequency cavities. For the project on MgB2, MgB2/Native-Oxide/Ag planar junctions are fabricated and characterized down to 2.1 K and in the magnetic field parallel to the sample surface up to 6 Tesla. This work investigates how pairbreaking affects the magnitude and phase of the order parameter in a multiband superconductor. The tunneling spectra are analyzed in the framework of a two-band model developed by our theory collaborator Prof. Alex Gurevich, Old Dominion University. The model allows the extraction of the pair-breaking parameters among other quantities. The analysis shows that the order parameter in the ? band is quickly suppressed in the field, the ? band is cleaner than the ? band. The ratio of pairbreaking parameter in the ? band to the ? band rapidly increases at fields higher than ~0.1 T and then plateau at higher fields. This transition around 0.1 T magnetic field suggests a phase decoupling in the two bands of MgB2. Below the transition, the two bands are phase-locked, so mostly, the superconductivity in the ? band is affected, and after phase decoupling, both bands are affected by the applied field. These results are important for a basic understanding of multiband superconductors and the application implications of this material. This phase decoupling has a new and profound consequence on the superconducting state of a multiband superconductor that has been theoretically predicted and never observed experimentally. For the Pb project, ultrathin films of Pb in ultrahigh vacuum conditions are deposited by e-beam evaporation and characterized with low-temperature scanning tunneling microscopy and spectroscopy (STM/STS). The STM/STS allows measuring the electronic density of states with the highest spatial resolution down to atomic scale. The shape of a superconducting vortex core is determined by the superconducting gap and the Fermi velocity, and the STM allows to map anisotropies of these quantities spatially. The vortex cores of Pb film show a complex shape that evolves from triangular at short distances from the center to a six-fold symmetric star shape farther away from the center. These details are very subtle, and they can be highlighted only if one works within the clean limit (to avoid the averaging effect of the scattering) and by fabricating the heterostructure that pins the vortices spatially. The complex vortex core shape reflects the anisotropy of the two bands that contribute to superconductivity in this material. For the project on Niobium, cold and hot spots from nitrogen-doped Nb cutouts are characterized by low temperature scanning tunneling microscopy and spectroscopy (STM/STS) combined with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The radiofrequency (RF) measurements of the quality factor and temperature mapping on an N-doped Nb superconducting resonator cavity are carried out at Jefferson Laboratory before cutting out the samples. This work aims to identify possible sources of excess dissipation in hot spots and relate them to the surface chemical composition and superconducting properties. The temperature mapping revealed a strong effect of the cavity cooldown rate on the intensities of hot spots and their spatial distribution, which indicates a significant contribution of trapped vortices to the RF dissipation. SEM images acquired on the cold and hot spots using a secondary electron detector show absence of residual hydride scars and niobium nitrides on their surface. Angle-resolved XPS measurements on the native surface of these samples revealed higher oxidized Nb 3d states on the N-doped Nb cold spots, which is supported by XPS depth profiles done on the samples by Argon ion sputtering. Argon ion sputtering of oxidized Nb removes oxygen preferentially from Nb2O5 and diffuses to bulk, thickening the lower oxidation state layers. The proximity theory framework’s tunneling spectra analysis suggests hot spots have stronger pairbreaking due to a weakly reduced pair potential, a thicker metallic suboxide layer, and a wide distribution of the contact resistance. STM imaging of vortex cores shows a triangular vortex lattice in both samples, and the coherence length is nearly the same in hot and cold spots. The experimental data analysis suggests weakly degraded superconducting properties at the surface of hot spot regions are not the primary sources of RF losses. Instead, they are the regions where vortices nucleate first and get trapped during cooling down. These experimental techniques and findings will be crucial in helping to qualify new recipes for SRF cavity production and to boost their performance. / Physics
106

Advanced NMR Studies of Fluoropolymers

Li, Xiaohong 29 July 2011 (has links)
No description available.
107

Moral Decoupling: Analysis of Possible Factors Causing Consumers to Ignore Brand’s Greenwashing Practices and the Effect on Purchase Intention

Cano Casas, Silvia Pilar, Valls Llufriu, Eugènia January 2022 (has links)
Background: Due to the growth of green markets, the phenomenon of greenwashing arises. This leads to consumers experiencing feelings of betrayal and having trust problems with the brand using this misleading tactic. Nevertheless, there is also literature indicating that some customers ignore this and do not alter their purchasing behavior by continuing to buy from these misbehaving brands. This can be explained by moral decoupling, which allows customers to separate their judgements of morality from their judgements of the company's performance. In addition to this, three further variables were analyzed, to comprehend this concept better. Purpose: This study's goal was to retest relationships established in previous research, concretely moral decoupling linked with brand identity fusion, purchase intention and the regulatory focus theory in the context of a greenwashing infraction. By retesting and further proving these, this study’s contribution would have been to propose the expansion of the moral decoupling model with the mentioned variables. Also, this study would expand the existing literature on causes of customer behavioral responses and bring light and study further the detrimental practice of greenwashing.  Method: The foundation of this study was previous literature, which helped construct three hypotheses that were tested via an online questionnaire that has 122 usable responses. In summary, this study follows a deductive approach using quantitative methods to fulfill the purpose of this explanatory, positivist research.  Conclusion: There was not enough evidence to support hypotheses 1 and 2. These stated that regulatory focus influences moral decoupling in a greenwashing context, promotion focus negatively and prevention positively, and that brand identity fusion influences moral decoupling positively in a greenwashing context. The third hypothesis stating that moral decoupling positively influences purchase intention was only proven in the English survey. The overall results contradict the findings of the literature this study is based on, meaning that future research is needed to reconcile these differences.
108

Unveiling Consumer Perception: Exploring the Impact of Decoupling Product Ownership : Decoupling of white goods ownership

Akter, Sharmin, Raja, Sana January 2023 (has links)
The sharing economy enables sustainable consumption through efficient access to products, but transitioning from ownership to a subscription-based model faces barriers. The thesis author explored how the decoupling of product ownership impact on the variables; consumer's perceptions of - psychological value, monetary value, social value, brand image, brand attachment, brand loyalty, service quality, and product quality and performance in the context of white goods. Furthermore, the thesis authors added sustainability awareness as an important variable, while discussing the decoupling of product ownership. Although, there is a lot of literature on the above-mentioned variables the relationship between the decoupling of product ownership and the mentioned variables was theoretically and empirically unexplored. Using a quantitative and deductive research approach, an online survey consisting of 29 questions was conducted. The empirical data revealed that the decoupling of product ownership impact all the variables under study and have a significant relationship with them. The impact of decoupling of product ownership was found to be strongest on consumers' perception of - service quality, followed by brand loyalty, brand attachment, product quality and performance, and monetary value. By gaining a deeper understanding of the relationships between the variables companies can effectively develop marketing strategies, subscription plans, and pricing strategies.
109

Centerpartiets mittenidentitet : Religiöst beteende i den politiska vardagen / The Centre Party’s middle identity : Religious behaviour in everyday politics

Sörensen, Stellan January 2022 (has links)
Den breda mitten, eller bara mitten, är ett centralt begrepp i Centerpartiets identitet. Trots detta är Centerpartiets sakpolitik inte särskilt positionerad i ”mitten”. Partiet är snarare det mest högerlutande partiet av samtliga riksdagspartier vad gäller ekonomiska frågor. Samtidigt är själva idén med den breda mitten att etablera ett bredare samarbete över blockgränser men exkludera Vänsterpartiet och Sverigedemokraterna på grund av deras respektive ytterkantsposition. Rent sakpolitiskt är den breda mitten en gåta. Medan fenomenet inte tillåter sig att begripas speciellt väl ur ett sakpolitiskt perspektiv, argumenterar föreliggande uppsats för att det bättre kan förstås utifrån dess symboliska betydelse. Den breda mitten undersöks således som en instans av sekulär religion. Genom intervjuer med Centerpartister kartläggs ett religiöst meningssystem som grundas på; (1) ett heligt ideal om en icke-extrem politisk karaktär i form av mitten; (2) en moralisk gemenskap som sluter upp kring idealet och försvarar det från all form av upplevd extremism, men som är mer intresserad av sitt förakt för Sverigedemokraterna och (3) upplevelser av hur ritualer kring motståndet mot Sverigedemokraterna och självuppoffring för idealet erbjuder frälsning från synden att kunna associeras med Sverigedemokraterna via högeridentiteten. Religionens funktion tolkas vara att reglera diskrepansen mellan partiets identitet och praktik genom ritualer och moraliska argument som triumferar över sakliga problem med motstånd mot Sverigedemokraterna som den övertygande mekanismen. Mitten identifieras vidare som den perfekta täckmanteln för en förlorad högeridentitet och för de framgångar som motståndet mot Sverigedemokraterna bringar partiet, då motstånd mot båda ytterkantspartierna gör att Centerpartiet kan hävda sig som mitten och därigenom attrahera den större grupp väljare som finns där. Motståndet mot Sverigedemokraterna tolkas i sin tur som den grundläggande drivkraften bakom fenomenet den breda mitten, en drivkraft som inte bara bygger på framgångar i termer av en ökad väljarbas utan också på en upplevd välvilja, en dold förhoppning om en alternativ och självständig högergemenskap men även på en möjlighet för Centerpartiet att göra upp med sin egen historia av främlingsfientlighet. / The broad middle, or just the middle, is a central concept in the identity of The Centre Party in Sweden. Despite this, the politics of The Centre Party is not particularly positioned in “the middle”. Rather, The Centre Party is the most right-leaning party of all the parliamentary parties when it comes to economic issues. Simultaneously, the very idea behind the broad middle is to establish wider cooperation across block boundaries but exclude the parliamentary parties The Left Party and The Sweden Democrats due to their respective outer edge position. As a matter of concrete policy, the broad middle is an enigma. While the phenomenon does not allow itself to be understood particularly well from a concrete political perspective, the present thesis argues that it can be better understood based on its symbolic meaning. The broad middle is thus analysed as an instance of secular religion. Through interviews with members of The Centre Party, a religious meaning system is mapped which is based on; (1) a sacred ideal of a non-extreme political character in the form of the middle; (2) a moral community that defends the ideal by protecting it from all sorts of experienced extremism, but whose interest lies more in its contempt for The Sweden Democrats and (3) experiences of how rituals surrounding the antagonism towards The Sweden Democrats and self-sacrifice for the ideal offers salvation from the sin of being associated with The Sweden Democrats trough a Right-wing identity. The function of the religion is interpreted as regulating the discrepancy between The Centre Party’s identity and practise through rituals and moral arguments that triumphs over factual problems with the antagonism towards The Sweden Democrats as the convincing mechanism. The middle is further identified as the perfect cover for a lost Right-wing identity and for the successes that the antagonism towards The Sweden Democrats brings the party, since opposition to both the outer-edge parties allows The Centre Party to assert itself as the middle and thus attract the larger group of voters who are located there. The antagonism towards The Sweden Democrats is in turn identified as the primal driving force behind the phenomenon the broad middle, a driving force that is not only based on successes in term of increased voters but also on an experienced benevolence, a hidden hope for an alternative and independent Right-wing community as well as on an opportunity for redemption with The Centre Party’s own history of xenophobia.
110

Mutual-coupling isolation using embedded metamaterial EM bandgap decoupling slab for densely packed array antennas

Alibakhshikenari, M., Khalily, M., Virdee, B.S., See, C.H., Abd-Alhameed, Raed, Limiti, E. 09 April 2019 (has links)
Yes / This article presents a unique technique to enhance isolation between transmit/receive radiating elements in densely packed array antenna by embedding a metamaterial (MTM) electromagnetic bandgap (EMBG) structure in the space between the radiating elements to suppress surface currents that would otherwise contribute towards mutual coupling between the array elements. The proposed MTM-EMBG structure is a cross-shaped microstrip transmission line on which are imprinted two outward facing E-shaped slits. Unlike other MTM structures there is no short-circuit grounding using via-holes. With this approach, the maximum measured mutual coupling achieved is -60 dB @ 9.18 GHz between the transmit patches (#1 & #2) and receive patches (#3 & #4) in a four-element array antenna. Across the antenna’s measured operating frequency range of 9.12 to 9.96 GHz, the minimum measured isolation between each element of the array is 34.2 dB @ 9.48 GHz, and there is no degradation in radiation patterns. The average measured isolation over this frequency range is 47 dB. The results presented confirm the proposed technique is suitable in applications such as synthetic aperture radar (SAR) and multiple-input multiple-output (MIMO) systems. / H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E0/22936/1

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