- About
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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.
Search results
Showing 51 to 58 of 58 (0.021 seconds)| 51 |
Teoretická studie magnetické anizotropie v magnetických tunelových spojích na bázi MgO / Theoretical Study of Magnetic Anisotropy in MgO-based Magnetic Tunnel JunctionsVojáček, Libor January 2021 (has links)
Magnetický tunelový spoj (MTJ) je spintronická součástka komerčně používaná ve vysoce citlivých čtecích hlavách pevných disků. Počínaje rokem 2007 přispěla k udržení exponenciálního nárůstu hustoty magnetického zápisu. Kromě toho se také stala stavebním kamenem rychlé, odolné, úsporné a nevolatilní magnetické paměti s přímým přístupem (MRAM). Tento nový typ polovodičové paměti, stejně jako je tomu u čtecích hlav disků, využívá tunelové spoje založené na krystalickém oxidu hořečnatém (MgO) spolu s 3d kovovými magnetickými prvky (Fe a Co). Pro zmenšení MTJ a současné udržení dlouhodobé stability paměti proti tepelným fluktuacím je zapotřebí silná magnetická anizotropie ve směru kolmém na rozhraní kov|MgO. V této práci proto nejdříve provedeme analýzu magnetokrystalické anizotropie (MCA) kubického prostorově centrovaného Fe, Co a Ni na MgO pomocí ab initio simulací. Dále bude vyvinut program pro výpočet tvarové anizotropie, která je kromě MCA velmi podstatná, neboť v součtu dávají efektivní anizotropii. Na závěr implementujeme program pro výpočet MCA na základě poruchové teorie druhého řádu. To nám umožní dát pozorované anizotropní vlastnosti do souvislosti přímo s elektronickou strukturou systému (pásovou strukturou a hustotou stavů).
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Electro - Quasistatic Body Communication for Biopotential ApplicationsShreeya Sriram (10195706) 25 February 2021 (has links)
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<p>The current state of the art in biopotential recordings rely on radiative electromagnetic
(EM) fields. In such transmissions, only a small fraction of this energy is received since the
EM fields are widely radiated resulting in lossy inefficient systems. Using the body as a communication medium (similar to a ’wire’) allows for the containment of the energy within the
body, yielding order(s) of magnitude lower energy than radiative EM communication. The
first part of this work introduces Animal Body Communication for untethered rodent biopotential recording and for the first time this work develops the theory and models for animal
body communication circuitry and channel loss. In vivo experimental analysis proves that
ABC successfully transmits acquired electrocardiogram (EKG) signals through the body with
correlation greater than 99% when compared to traditional wireless communication modalities, with a
50x reduction in power consumption. The second part of this work focusses on the analysis
and design of an Electro-Quasistatic Human Body Communication (EQS-HBC) system for
simultaneous sensing and transmission of biopotential signals. In this work, detailed analysis on the system level interaction between the sensing and transmitting circuitry is studied
and a design to enable simultaneous sensing and transmission is proposed. Experimental
analysis was performed to understand the interaction between the Right Leg-Drive circuitry
and the HBC transmission along with the effect of the ADC quantization on signal quality.
Finally, experimental trials proves that EKG signals can be transmitted through the body
with greater than 96% correlation when compared to Bluetooth systems at extremely low powers. </p>
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First Principles-Based Interatomic Potentials for Modeling the Body-Centered Cubic Metals V, Nb, Ta, Mo, and WFellinger, Michael Richard 23 July 2013 (has links)
No description available.
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Resilience and Toughness Behavior of 3D-Printed Polymer Lattice Structures: Testing and ModelingAl Rifaie, Mohammed Jamal 21 August 2017 (has links)
No description available.
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Variational models in martensitic phase transformations with applications to steelsMuehlemann, Anton January 2016 (has links)
This thesis concerns the mathematical modelling of phase transformations with a special emphasis on martensitic phase transformations and their application to the modelling of steels. In Chapter 1, we develop a framework that determines the optimal transformation strain between any two Bravais lattices and use it to give a rigorous proof of a conjecture by E.C. Bain in 1924 on the optimality of the so-called Bain strain. In Chapter 2, we review the Ball-James model and related concepts. We present some simplification of existing results. In Chapter 3, we pose a conjecture for the explicit form of the quasiconvex hull of the three tetragonal wells, known as the three-well problem. We present a new approach to finding inner and outer bounds. In Chapter 4, we focus on highly compatible, so called self-accommodating, martensitic structures and present new results on their fine properties such as estimates on their minimum complexity and bounds on the relative proportion of each martensitic variant in them. In Chapter 5, we investigate the contrary situation when self-accommodating microstructures do not exist. We determine, whether in this situation, it is still energetically favourable to nucleate martensite within austenite. By constructing different types of inclusions, we find that the optimal shape of an inclusion is flat and thin which is in agreement with experimental observation. In Chapter 6, we introduce a mechanism that identifies transformation strains with orientation relationships. This mechanism allows us to develop a simpler, strain-based approach to phase transformation models in steels. One novelty of this approach is the derivation of an explicit dependence of the orientation relationships on the ratio of tetragonality of the product phase. In Chapter 7, we establish a correspondence between common phenomenological models for steels and the Ball-James model. This correspondence is then used to develop a new theory for the (5 5 7) lath transformation in low-carbon steels. Compared to existing theories, this new approach requires a significantly smaller number of input parameters. Furthermore, it predicts a microstructure morphology which differs from what is conventionally believed.
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Optimisation d'un code de dynamique des dislocations pour l'étude de la plasticité des aciers ferritiques / Improvements on Dislocation Dynamics Codes for the study of irradiated RPV ferritic steel's plasticityGarcia Rodriguez, Daniel 15 February 2011 (has links)
Ces travaux de thèse s’inscrivent au sein d’une démarche multi-échelles visant à améliorer lacompréhension de la fragilisation par l’irradiation de l’acier de cuve. Dans ce cadre, nous nousintéressons à la description de la mobilité des dislocations dans la ferrite, l’une des entrées clépour les codes de dynamique de dislocations (DD). Nous présentons ainsi une revuebibliographique exhaustive des différentes théories et expressions de la mobilité, à partir delaquelle nous proposons une nouvelle expression pour les dislocations vis. Cette loi, utilisablepour la première fois dans le régime de transition ductile-fragile, permet de reproduire lesprincipales observations expérimentales disponibles à ce niveau. Finalement, nous montronsles améliorations apportées au code de DD Tridis BCC 2.0, qui intègrent la nouvelle loi demobilité avec une nouvelle gestion des segments de dislocation permettant de stabiliser etaccélérer des simulations complexes avec prise en compte du glissement dévié. / The present work is part of a larger multi-scale effort aiming to increase knowledge of thephysical phenomena underneath reactor pressure vessel irradiation embrittlement. Withinthis framework, we focused on the description of dislocation mobility in BCC iron, which is oneof the key inputs to dislocation dynamics (DD) simulation codes. An extensive bibliographicreview shows that none of the available expressions can deal with the ductile-fragile transitiondomain of interest. Here, a new screw mobility law able to reproduce the main experimentalobservations is introduced building on the previous models. The aforementioned law is usedtogether with an improved dislocations dynamics code Tridis BCC 2.0, featuring bothperformance and dislocations segments interaction management enhancements, that allowsfor complex DD simulations of BCC iron structures with cross-slip
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Le périple du métabolisme bactérien à travers le paysage fluvial du Saint-Laurent = A bacterial metabolic journey through the St. Lawrence riverscapeGrater, Elizabeth Mathilde January 2020 (has links) (PDF)
No description available.
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Low Velocity Impact and RF Response of 3D Printed Heterogeneous StructuresKeerthi, Sandeep January 2017 (has links)
No description available.
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