Дисертації з теми "BGG glasses"

Parmi les verres adaptés aux applications dans l'infrarouge moyen, les verres d’oxydes lourds Ga2O3 - GeO2 - BaO (ΒGG) se distinguent par leurs avantages uniques. Ces verres oxydes ont une faible énergie de phonon couplée à une température de transition vitreuse supérieure à 500°C, ainsi que des propriétés mécaniques et une durabilité chimique similaires à celles de la silice. La combinaison harmonieuse de ces propriétés fait du verre BGG un excellent candidat, offrant des performances améliorées par rapport à d'autres familles de verre opérant dans l’infrarouge moyen comme les verres fluorés ou les verres chalcogénures. En optimisant le rapport Ga/Ge pour favoriser les matrices gallates riches en gallium, l'énergie des phonons est encore minimisée et les propriétés mécaniques sont améliorées.Cette thèse aborde les défis actuels dans le développement de fibres optiques robustes et à faible perte fabriquées à partir de verres gallo-germanates (BGe) et de germano-gallates (BGa). L'étude de diverses compositions de verre BGG montre que l'oxyde d’yttrium seul agit comme un « stabilisateur » efficace de la matrice vitreuse, facilitant la production de verres thermiquement stables sans cristallisation pendant l’étape d’étirage. Une analyse de la structure locale du verre montre que l'iintroduction d’oxyde d'yttrium dans les verres germanates et gallo-germanates avec un rapport Ga/Ge compris entre 0.4 et 0.8 favorise la formation de sites de gallium GaO5 et GaO6. Cependant, dans les verres germano-gallates avec un rapport supérieur à 1.5, l’introduction d’oxyde d’yttrium n’impacte pas la coordinence du gallium, les cations de gallium n'existent que sous forme d'unités tétraédriques. Ce phénomène est dû à la présence d'un ratio 2Ba/Ga supérieur à 1.5, qui assure une quantité suffisante de baryum pour compenser la charge négative du gallium. Par conséquent, il suffit de 1 mol% d'yttrium pour stabiliser efficacement la composition du verre et empêcher la cristallisation en surface
Among the glasses tailored for mid-infrared applications, heavy metal oxides glass composition Ga2O3 - GeO2 - BaO stand out due to their unique advantages. These oxide glasses have low phonon energy coupled with a glass transition temperature above 500°C, as well as mechanical properties and chemical durability similar to silica. The harmonious combination of these properties positions BGG glass as a superior alternative, offering improved performance compared to other glass families operating in the mid-infrared such as fluoride or chalcogenide. By tuning the Ga/Ge ratio to favour gallium-rich gallate matrices, phonon energy is further minimised while mechanical properties are improved

An extensive study of a-FexTM 1-xZr2 with TM = {V, Cr, Mn, Co, Ni, Cu} was undertaken in order to gain insight into the glassy structure, the metastable "big-cube" structure of the intermediate crystallisation product, and the evolution process involved therein. The stability of the glassy state was examined by differential scanning calorimetry (DSC). Generally higher temperatures and more negative enthalpies of crystallisation were observed for the glass system where Fe was substituted with {Co, Ni, Cu} than for the system where Fe was substituted with {V, Cr, Mn}. A proposed hypothetical crystallisation mechanism involved in the evolution of the metastable cF96 state (instead of the equilibrium tI12 state) was tested. Oxygen impurities present in the amorphous state were shown to be responsible for nucleating the cF96 big cube. Upon removal of the oxygen nucleation sites through hydrogenation of the glasses, the crystallisation proceeded directly to the equilibrium tetragonal structure bypassing the metastable phase. The validity of an assumed invariant structure in late transition-early transition metal (LT-ET) binary glasses was examined by means of Mossbauer spectroscopy. Variations in isomer shift (delta) and quadrupole splitting (Delta) upon TM substitution were consistent with variations in the density of states (DOS) at the Fermi level (EF). An assumed constant structure for (4d ET)-(3d LT) glasses is indeed justified. Variations in atomic packing were followed by measuring Delta. Delta increased as the atomic number of the TM increased. For the a-Fe xCu1-xZr 2 series, a break in the concentration dependence of Delta at x ≈ 0.3 is observed which mirrors the change in crystallisation from cF96 to tI6. Furthermore, comparisons of the glassy, metastable cubic and equilibrium tetragonal Mossbauer spectral data show obvious similarities between the glass and big cube which strongly suggest the existence of a common local (short-range) order between the two

This thesis covers my reflections on the inspirations and the motivations behind selected works including my candidacy exhibition; Resonance and my thesis exhibition; after the big wind stops I see gentle waves. It contains my life throughout my MFA studies and the development of my art practice. Through its story-within-a-story method of narration and my describing streams of my thoughts, I am attempting to explain the processes of my development and the discoveries I have made, the little things in my daily life, and the big turning points that inspired me. My work and this document have been strongly determined by my poetic imagination and the emotional events and experiences I have had.

Bulk metallic glasses represent a newly developed class of materials. Some metallic glasses possess combinations of very good or even excellent mechanical, chemical and/or magnetic properties uncovering a broad range of both industrial and vital applications. Besides all advantages metallic glasses have also significant drawbacks, which have to be overcome for commercial application. Apart from low critical thicknesses, brittleness and chemical inhomogeneity one important problem of metallic glasses is the lack of an appropriate theory describing their structure. Therefore, the search for new glass forming compositions as well as the improving of existing ones occurs at present by means of trial-and-error methods and a number of empirical rules. Empirical rules for good glass-forming ability of bulk metallic glasses have been established in recent years by Inoue and Egami. Two of these rules, (i) Preference of more than 3 elements and (ii) Need of more than 12 % radii difference of base elements, seem to be closely related to topological (geometrical) criteria. From this point of view topological parameters contribute essentially to the glass-forming ability. The third rule (iii) demands a negative mixing enthalpy of base elements and refers to the chemical interaction of the atoms. The generalized Bernal’s model (hard-sphere approximation) was used for the simulation of monatomic, binary and multi-component structures. Excluding chemical interaction, this method allows the investigation of topological criteria of the glass-forming ability. Bernal’s hard-sphere model was shown to be a good approximation for bulk metallic glasses and metallic liquids and yields good coincidence of experimental and theoretical results. • The Laguerre (weighted Voronoi) tessellation technique was used as the main tool for the structural analysis. Due to very complex structures it is impossible to determine the structure of bulk metallic glasses by means of standard crystallographic methods. • Density, radial distribution function, coordination number and Laguerre polyhedra analysis confirm amorphism of the simulated structures and are in a good agreement with available experimental results. • The ratio of the fractions of non-crystalline to crystalline Laguerre polyhedra faces was introduced as a new parameter . This parameter reflects the total non-crystallinity of a structure and the amount of atomic rearrangements necessary for crystallization. Thus, the parameter is related to the glass-forming ability. It depends strongly on composition and atomic size ratio and indicates a region of enhanced glass-forming ability in binary mixtures at 80 % of small atoms and atomic size ratio of 1.3. All found maxima of parameter for ternary mixtures have compositions and size ratios which are nearly the same as for the binary mixture with the maximum value of . • A new method of multiple-compression was introduces in order to test the tendency towards densification and/or crystallization of the simulated mixtures. The results of the multiple-compression of monatomic mixtures indicate a limiting value of about 0.6464 for the density of the amorphous state. Further densification is necessarily connected to formation and growth of nano-crystalline regions. • The results of the multiple-compression for binary mixtures shows a new maximum of the density at the size ratio of 1.3 and 30 % to 90 % of small atoms. This maximum indicates a local island of stability of the amorphous state. The maximal receivable density without crystallization in this region is enhanced compared to neighbouring regions. • The comparison of the parameter and the density to the distribution of known binary bulk metallic (metal-metal) glasses clearly shows that both parameters play a significant role in the glass-forming ability. • The polyhedra analysis shows regions with enhanced fraction of the icosahedral short-range order (polyhedron (0, 0, 12)) in the binary systems with the maximum at 80 % of small atoms and size ratio of 1.3. Comparison of the distribution of the (0, 0, 12) polyhedra to the distribution of known binary metallic (metal-metal) glasses and to the parameter shows that icosahedral short-range order is not related to the glass-forming ability and is a consequence of the high non-crystallinity (high values of ) of the mixtures and non vice versa. Results for the ternary mixtures confirm this observation. • A new approach for the calculation of the mixing enthalpy is proposed. The new method is based on the combination of Miedema’s semi-empirical model and Laguerre tessellation technique. The new method as well as 6 other methods including the original Miedema’s model were tested for more than 1400 ternary and quaternary alloys. The results show a better agreement with experimental values of the mixing enthalpy for the new model compared to all other methods. The new model takes into account the local structure at atom site and can be applied to all metallic alloys without additional extrapolations if the atomic structure of the considered alloy is known from a suitable atomistic structure model.

Recent trends to miniaturized systems such as smartphones and wearables, as well as the rise of autonomous vehicles relying on all-electric and smart in-car systems, have brought unprecedented needs for superior performance, functionality, and cost requirements. Transistor scaling alone cannot meet these metrics unless the remaining system components such as substrates and interconnections are scaled down to bridge the gap between transistor and system scaling. In this regard, 3D glass system packages have emerged as a promising alternative due to their ultra-short system interconnection lengths, higher component densities and system reliability enabled by the tailorable coefficient of thermal expansion (CTE), high dimensional stability and surface smoothness, outstanding electrical properties and low-cost panel-level processability of glass. The research objectives are to demonstrate board-level reliability of large, thin, glass packages directly mounted on PCB with conventional BGAs at pitches of 400µm SMT and smaller. Two key innovations are introduced to accomplish the objectives: a.) Reworkable circumferential polymer collars providing strain-relief at critical high stress concentration areas in the solder joints, b.) novel Mn-doped SACMTM solder to provide superior drop test performance without degrading thermomechanical reliability. Modeling, package and board design, fabrication and reliability characterization were carried out to demonstrate reliable board-level interconnections of large, ultra-thin glass packages. Finite-element modeling (FEM) was used to investigate the effectiveness of circumferential polymer collars as a strain-relief solution on fatigue performance. Experimental results with polymer collars indicated a 2X improvement in drop performance and 30% improvement in fatigue life. Failure analysis was performed using characterization techniques such as confocal surface acoustic microscopy (C-SAM), optical microscopy, X-ray imaging, and scanning electron microscopy/energy dispersive spectrometry (SEM/EDS). Model-to-experiment correlation was performed to validate the effectiveness of polymer collars as a strain-relief mechanism. Enhancement in board-level reliability performance with advances in solder materials based on Mn-doped SACMTM is demonstrated in the last part of the thesis.The studies, thus, demonstrate material, design and process innovations for package-to-board interconnection reliability with ultra-thin, large glass packages.

An investigation into the phase transformation of metastable alloys such as high entropy alloys (HEAs) and high entropy bulk metallic glasses (HE-BMGs) was performed. Bulk metallic glasses (BMGs) and HEAs were known to have a metastable phase at high temperature, while HEAs was reported to have a sluggish diffusion at high temperature. Besides, the drawback of many single phase HEAs is that they are mechanically unstable due to the presence of single phase either body centred cubic (BCC) or face centred cubic (FCC) structures. Here, a systematic study on the crystal structure, physical and mechanical properties of TiZrHfNiCu HE-BMG and FeCoNi(BxAl1-x)0.1Si0.1 (0 ≤ x ≤ 1) lamellar structured HEA were explored. It was revealed that, a phase transformation occurred in HE-BMG in isothermal and non-isothermal conditions, yet the nucleation and growth behaviour was relatively slow at high temperature compared to most Zr-based amorphous alloys. This phenomenon was proven by the attained data of activation energy and crystallisation mechanism which reflect the crystallisation resistance of the alloy. The addition of boron as a substitution of aluminium in FeCoNi(BxAl1-x)0.1Si0.1 alloy changed the phase formation, phase stability, morphology characteristics and mechanical properties of the alloy. The unique lamellar herringbone-like structure was formed with increasing boron content and led to improvement of mechanical properties of the alloy such as the hardness from B0.4 to B1.0. Lamellar structured-HEA was designed to obtain a balance in strength and ductility for FeCoNi(Bx Al1-x)0.1Si0.1 HEA where it can be tailored by modifying the boron content. The optimum balance of strength (1550 MPa) and ductility (19%) was attained at 0.5 at% boron content.

Emerging I/O density and bandwidth requirements are driving packages to low-CTE silicon, glass and organic substrates for higher wiring density and reliability of interconnections and Cu-low k dielectrics. These are needed for high performance applications as 2.5D packages in large-size, and also as ultra-thin packages for consumer applications that are directly assembled on the board without the need for an intermediate package. The trend to low-CTE packages (CTE of 3-8ppm/°C), however, creates large CTE mismatch with the board on which they are assembled. Interconnection reliability is, therefore, a major concern when low CTE interposers are surface mounted onto organic system boards via solder joints. This reliability concern is further aggravated with large package sizes and finer pitch. For wide acceptance of low CTE packages in high volume production, it is also critical to assemble them on board using standard Surface Mount Technologies (SMT) without the need for under-fill. This research aims to demonstrate reliable 400 micron pitch solder interconnections from low CTE glass interposers directly assembled onto organic boards by overcoming the above challenges using two approaches; 1) Stress-relief dielectric build up layers on the back of the interposer, 2) Polymer collar around the solder bumps for shear stress re-distribution. A comprehensive methodology based on modeling, design, test vehicle fabrication and characterization is employed to study and demonstrate the efficacy of these approaches in meeting the interposer-to-board interconnection requirements. The effect of varying geometrical and material properties of both build-up layers and polymer collar is studied through Finite Element Modeling. Interposers were designed and fabricated with the proposed approaches to demonstrate process feasibility.

Business Administration/Entrepreneurship
Ph.D.
This dissertation explores the connection between founder personality and organizational culture in founder-led entrepreneurial companies. With a focus on how founder personality affects culture, it draws from the literature in upper echelon/top management teams, family business and organizational psychology – notably the Attraction-Selection-Attrition (ASA: Schneider, 1987) and Person-Organization fit (P-O: O'Reilly, Chatman, & Caldwell, 1991) theories. Using a combination of ethnographic, psychological and organizational data from the founders and employees of four small firms from multiple industries, and a broader survey study of 336 respondents from 23 firms, it finds support for O’Reilly et al., (2014)’s CEO Personality-Culture link in the small-company setting. It also validates two new findings: 1) that employee personality traits can trump founder personality as an influence on culture, and 2) that founder involvement can moderate the impact of founder personality on culture. The dissertation concludes with plans for further research into the personality-organizational culture effects and thoughts about the applicability of these results for founders and consultants.
Temple University--Theses

Women have a few managerial positions compared to men in audit and accounting firms. It said that large companies have intentions to increase the number of women accountants in managerial positions. The study is investigating the implementation of gender policies and diversity in auditing firm with a specific focus on how company size may impact how organizations come to work with issues of gender and diversity. A qualitative method has been implemented in this study, by conducting 17 semi-structured interviews with women auditors and accountants, working in 4 large firms and 5 small firms in Sweden. The study shows that the policies of the large companies are not fully implemented. While setting policies for small firms will just help women auditors/accountants to improve their career education.

La structure amorphe des verres métalliques (VM) leur confère des résistances mécaniques hors du commun. Elle est également à l'origine des mécanismes de déformations plastiques qui leur sont spécifiques et qui se traduit par la localisation spatiale de la déformation menant à la création et la propagation de bandes de cisaillement. L'impact de ces mécanismes de déformation reste néanmoins encore mal connu concernant les sollicitions mécaniques complexes, il est par exemple très difficile de prédire les évolutions de l'usure d'un VM dans un système complexe et donc sa durée de vie qui est intimement liée à la perte de matière. Ces travaux ont ainsi pour but de comprendre la réponse mécanique des VM vis à vis des mécanismes de déformation qui leurs sont propres, lors d'essais de rayure, sur trois verres métalliques différents base Zr et Cu.La comparaison des essais de rayure à ceux d'indentation a révélé l'importance de la résistance au cisaillement dans les VM dès que l'indenteur exerce une force latérale, entraînant la création de bandes de cisaillement à l'avant du passage de l'indenteur. L'activation du mécanisme d'adoucissement propre aux VM a ainsi été mise en lumière. Ce dernier favorise alors l'enfoncement de l'indenteur lors de la rayure. Des modifications de la structure des VM étudiés, et donc des propriétés mécaniques, ont ensuite été réalisées à l'aide de traitements thermiques de relaxation et de cristallisation partielle permettant de discuter le rôle de la dureté mais aussi de l'importance de la ténacité. Ainsi le VM le plus dur n'est pas forcement, comme généralement admis dans la communauté scientifique, le verre possédant la plus grande résistance à la rayure. Grâces aux résultats obtenus, des stratégies ciblées pour les différents types de VM existants sont proposées afin de limiter leur usure lors de la rayure
Metallic glasses (MGs) exhibit incredible mechanical properties arising from their particular amorphous structure. This structure is also responsible for the specific deformation mechanisms of MG leading to the nucleation and propagation of shear bands (SBs). Nevertheless, under complex loading, the deformation mechanisms remain to be understood, for example, it isnearly impossible to predict the wear behaviour and so, the lifetime which isdirectly linked to the wear loss of a metallic glass sample. This work aims to understand the mechanical behaviour of MGs, in light of their specific deformation mechanisms, under scratch test for three differents Zr- and Cu-based MGs.The analogy of indentation and scratch tests revealed the importance of the shear strength for MGs. Indeed, the introduction of a lateral force in the case of a scratch test induces the creation of SBs ahead of the tip of the indenter. The activation of the softening mechanism has also been pointed out, which leads to the sink in of the indenter during a scratch test. The study of thermally treated MGs (relaxed and partially crystalized) helps us revealing the impact of the hardness along with the fracture toughness on the wear resitance of a MG. Thereby, the MG showing the best wear resistance is not necessarily the hardest MG, as admitted by the scientific community. Eventually, different strategies in agreements with the results shown in this work, are discussed in order to minimize the wear during the scratch of a MG

Dans la présente thèse de doctorat je présente des résultats concernant des modèles désordonnés et frustrés venant de la physique statistique et de l'optimisation combinatoire. Comme application de la théorie des verres de spins, j'étudie le modèle de Blume, Emery et Griffiths désordonné et frustré. Ce modèle est traité dans l'approximation de champ moyen dans le cadre de la méthode des répliques A l'aide de l'Ansatz symétrique dans les répliques je présente une solution numérique complète puis je discute des effets de brisure de cette symétrie La stabilité de la solution symétrique a été Rudik et les régions instables identifiées Le diagramme de phase exhibe des transitions de premier et de second ordre. Le point tricritique persiste dans le modèle frustré, Ce qui est en accord avec des travaux antérieurs une version du modèle BEG avec un potentiel chimique désordonné a également été étudiée. les calculs confirment que le point tricritique apparaît à plus basse température quand il y a du désordre. Ensuite je considère le problème de la bipartition d'un graphe. Ce problème correspond du point de vue de la physique statistique h un verre de spins soumis h une contrainte d'aimantation totale nulle. je considère les propriétés statistiques des solutions de faible énergie engendrées par des algorithmes heuristiques. de tels algorithme sont en général conçus pour résoudre des problèmes d'optimisation combinatoire qui sont NP- difficiles. Plusieurs heuristiques ont 60 implémentées pour le problème de la bipartition de graphe. des lois d'échelle ont été obtenues : en particulier la moyenne et la variance du coût obéissent A une loi linéaire en N. Par conséquent le coût obtenu par des heuristiques est une quantité auto-moyennante. je suggère que cette propriété est générale valable aussi pour les solutions aléatoires pour les solutions quasi-optimales et pour les solutions optimales. En outre je propose une procédure pour comparer des algorithmes heuristiques. Cette procédure tient compte de la qualité de la solution aussi bien que du temps de calcul utilisé. Dans la troisième partie de ma thèse j'ai étudié en détail les propriétés h température nulle des verres de spins sur des graphes aléatoires lacunaires avec une coordination fixe. les verres de spins sur de tels graphes peuvent être considérés comme une approximation aux vrais verres de spins qui est plus réaliste que le modèle de Sherrington et Kirkpatrick. J'ai conçu un nouvel algorithme pour trouver les états fondamentaux. Aussi je teste numériquement une conjecture de Banavar, Sherrington et Sourlas qui donne la densité d'énergie du fondamental dans la limite de grande taille en fonction de la coordination. La distribution du paramètre d'ordre se révèle être non triviale et les données présentent une forte indication de la présence d'ultramétricité pour toutes les valeur de la coordination. Ces résultats confirment que les propriétés particulières des verres de spin, déduites an niveau de l'approximation de champ moyen dans le cadre du modèle de Sherrington et Kirkpatrick, sont aussi présentes pour des modèles plus réalistes comme les verres de spins sur des graphes aléatoires lacunaires avec une coordination fixe.

In the last few years some Music Information Retrieval (MIR) researchers have spotted important drawbacks in applying standard successful-in-monophonic algorithms to polyphonic music classification and similarity assessment. Noticeably, these so called “Bag-of-Frames” (BoF) algorithms share a common set of assumptions. These assumptions are substantiated in the belief that the numerical descriptions extracted from short-time audio excerpts (or frames) are enough to capture relevant information for the task at hand, that these frame-based audio descriptors are time independent, and that descriptor frames are well described by Gaussian statistics. Thus, if we want to improve current BoF algorithms we could: i) improve current audio descriptors, ii) include temporal information within algorithms working with polyphonic music, and iii) study and characterize the real statistical properties of these frame-based audio descriptors. From a literature review, we have detected that many works focus on the first two improvements, but surprisingly, there is a lack of research in the third one. Therefore, in this thesis we analyze and characterize the statistical distribution of common audio descriptors of timbre, tonal and loudness information. Contrary to what is usually assumed, our work shows that the studied descriptors are heavy-tailed distributed and thus, they do not belong to a Gaussian universe. This new knowledge led us to propose new algorithms that show improvements over the BoF approach in current MIR tasks such as genre classification, instrument detection, and automatic tagging of music. Furthermore, we also address new MIR tasks such as measuring the temporal evolution of Western popular music. Finally, we highlight some promising paths for future audio-content MIR research that will inhabit a heavy-tailed universe.
En el campo de la extracción de información musical o Music Information Retrieval (MIR), los algoritmos llamados Bag-of-Frames (BoF) han sido aplicados con éxito en la clasificación y evaluación de similitud de señales de audio monofónicas. Por otra parte, investigaciones recientes han señalado problemas importantes a la hora de aplicar dichos algoritmos a señales de música polifónica. Estos algoritmos suponen que las descripciones numéricas extraídas de los fragmentos de audio de corta duración (o frames ) son capaces de capturar la información necesaria para la realización de las tareas planteadas, que el orden temporal de estos fragmentos de audio es irrelevante y que las descripciones extraídas de los segmentos de audio pueden ser correctamente descritas usando estadísticas Gaussianas. Por lo tanto, si se pretende mejorar los algoritmos BoF actuales se podría intentar: i) mejorar los descriptores de audio, ii) incluir información temporal en los algoritmos que trabajan con música polifónica y iii) estudiar y caracterizar las propiedades estadísticas reales de los descriptores de audio. La bibliografía actual sobre el tema refleja la existencia de un número considerable de trabajos centrados en las dos primeras opciones de mejora, pero sorprendentemente, hay una carencia de trabajos de investigación focalizados en la tercera opción. Por lo tanto, esta tesis se centra en el análisis y caracterización de la distribución estadística de descriptores de audio comúnmente utilizados para representar información tímbrica, tonal y de volumen. Al contrario de lo que se asume habitualmente, nuestro trabajo muestra que los descriptores de audio estudiados se distribuyen de acuerdo a una distribución de “cola pesada” y por lo tanto no pertenecen a un universo Gaussiano. Este descubrimiento nos permite proponer nuevos algoritmos que evidencian mejoras importantes sobre los algoritmos BoF actualmente utilizados en diversas tareas de MIR tales como clasificación de género, detección de instrumentos musicales y etiquetado automático de música. También nos permite proponer nuevas tareas tales como la medición de la evolución temporal de la música popular occidental. Finalmente, presentamos algunas prometedoras líneas de investigación para tareas de MIR ubicadas, a partir de ahora, en un universo de “cola pesada”.
En l’àmbit de la extracció de la informació musical o Music Information Retrieval (MIR), els algorismes anomenats Bag-of-Frames (BoF) han estat aplicats amb èxit en la classificació i avaluació de similitud entre senyals monofòniques. D’altra banda, investigacions recents han assenyalat importants inconvenients a l’hora d’aplicar aquests mateixos algorismes en senyals de música polifònica. Aquests algorismes BoF suposen que les descripcions numèriques extretes dels fragments d’àudio de curta durada (frames) son suficients per capturar la informació rellevant per als algorismes, que els descriptors basats en els fragments son independents del temps i que l’estadística Gaussiana descriu correctament aquests descriptors. Per a millorar els algorismes BoF actuals doncs, es poden i) millorar els descriptors, ii) incorporar informació temporal dins els algorismes que treballen amb música polifònica i iii) estudiar i caracteritzar les propietats estadístiques reals d’aquests descriptors basats en fragments d’àudio. Sorprenentment, de la revisió bibliogràfica es desprèn que la majoria d’investigacions s’han centrat en els dos primers punts de millora mentre que hi ha una mancança quant a la recerca en l’àmbit del tercer punt. És per això que en aquesta tesi, s’analitza i caracteritza la distribució estadística dels descriptors més comuns de timbre, to i volum. El nostre treball mostra que contràriament al què s’assumeix, els descriptors no pertanyen a l’univers Gaussià sinó que es distribueixen segons una distribució de “cua pesada”. Aquest descobriment ens permet proposar nous algorismes que evidencien millores importants sobre els algorismes BoF utilitzats actualment en diferents tasques com la classificació del gènere, la detecció d’instruments musicals i l’etiquetatge automàtic de música. Ens permet també proposar noves tasques com la mesura de l’evolució temporal de la música popular occidental. Finalment, presentem algunes prometedores línies d’investigació per a tasques de MIR ubicades a partir d’ara en un univers de “cua pesada”.

To reach the net-zero carbon goal by 2045, the Swedish government want to push the building and construction sector to lower their greenhouse gas emissions. This push is performed by implementing a law requiring building developers to perform a climate declaration over greenhouse gas emissions, to receive a building’s final clearance. The climate declaration is limited to only include emissions from material extraction until completed building. However, there is a varying knowledge level in the industry regarding how to perform a climate declaration as well as how different materials impact the result. Therefore, this study aims to bring clarity concerning the topic, by investigating where the major and minor climate impacts occur in a building process. Additionally, the impact of different insulations materials and how they influence the result of a climate declaration is studied. To answer the research questions, a climate declaration is performed on a Swedish preschool. The insulation material in the building is altered between glass wool, stone wool, cellulose fibre, foam glass, and polystyrene insulation in different scenarios to see how it impacts the result. The stone wool scenarios use both carbon neutral and non-carbon neutral insulation. Cellulose fibre uses both loose wool with data from an EPD and board insulation with data from Boverket’s climate database in the scenarios. The major climate impact derives from the product stage (A1–A3), meaning material selection have a significant impact on the climate declaration result. The building element with the highest climate impact is the inner walls followed by the foundation, while the floor construction, roof and outer walls have the lowest climate impact. On a material level, plaster board, building plywood and concrete have the highest climate impact in the reference building. The cedar panel have the lowest climate impact and is the only carbon negative material in the reference building. However, this is due to different assumptions made in the climate impact data concerning the binding of carbon in organic materials. The results showed that the insulation material with the highest climate impact is non-carbon neutral stone wool that is 16 % higher than the original construction with glass wool, while loose cellulose wool has the lowest climate impact. The climate impact from the scenario with non-carbon neutral stone wool in the wall and roof construction is 33 % higher compared to the corresponding loose cellulose wool scenario. The scenario with the lowest climate impact, with loose cellulose wool, is approximately 13 % lower than the corresponding glass wool scenario. The carbon neutral stone wool scenario has a similar result to glass wool. Foam glass has a 9.5 % higher climate impact compared to polystyrene insulation in the foundation. Regarding the selection of insulation material, it influences the climate declaration by changing the climate impact. The influence derives from a combination of climate impact per unit and material quantity used in the building. The material quantity is partly dependant on the thermal conductivity (λ-value) of the insulation material. The climate declaration shows a limited view of a building’s environmental impact for a limited part of its lifecycle. Therefore, we would recommend additional lifecycle stages and environmental impacts to be part of the climate declaration in the future, as a means to avoid suboptimization and unintentional problem shifting.
För att nå klimatneutralitetsmålet 2045 vill den svenska regeringen driva bygg- och fastighetssektorn till att sänka sina växthusgasutsläpp. Denna insats utförs genom att införa en lag som kräver att byggherrar utför en klimatdeklaration över växthusgasutsläpp för att få ett slutbesked för byggnaden. Klimatdeklarationen är begränsad till att endast omfatta utsläpp från materialutvinning fram till färdig byggnad. Det finns dock en varierande kunskapsnivå i branschen om hur en klimatdeklaration utförs samt hur olika material påverkar resultatet. Därför syftar denna studie till att ge klarhet angående ämnet genom att undersöka var de större och mindre inflytandena på klimatpåverkan förekommer i en byggprocess. Dessutom studeras effekterna av olika isoleringsmaterial och hur de påverkar resultatet av en klimatdeklaration. För att besvara frågeställningarna utförs en klimatdeklaration på en svensk förskola. Isoleringsmaterialet i byggnaden ändras mellan glasull, stenull, cellulosafiber, skumglas och cellplast i olika scenarier för att se hur det påverkar resultatet. I stenullscenarierna används både koldioxidneutral och icke-koldioxidneutral isolering. Cellulosafibrer använder både lösull med data från en EPD och skivisolering med data från Boverkets klimatdatabas i scenarierna. Den största klimatpåverkan kommer från produktstadiet (A1–A3), vilket innebär att materialvalet har en betydande inverkan på klimatdeklarationsresultatet. Byggnadselementet med störst klimatpåverkan är innerväggarna följt av grunden, medan bjälklaget, taket och ytterväggarna har lägst klimatpåverkan. På materialnivå har gipsskivor, plywood och betong den högsta klimatpåverkan i referensbyggnaden. Cederpanelen har lägst klimatpåverkan och är det enda koldioxidnegativa materialet i referensbyggnaden. Detta beror dock på olika antaganden i klimatpåverkan angående bindningen av kol i organiska material. Resultaten visade att isoleringsmaterialet med den högsta klimatpåverkan är icke-koldioxidneutral stenull, som är 16 % högre än originalkonstruktionen med glasull, medan lös cellulosaull har lägst klimatpåverkan. Klimatpåverkan från scenariot med icke koldioxidneutral stenull i vägg- och takkonstruktion är 33 % högre jämfört med motsvarande scenario med lös cellulosaull. Scenariot med lägst klimatpåverkan, med lös cellulosaull, är cirka 13 % lägre än motsvarande glasullscenario. Det koldioxidneutrala stenullscenariot har ett liknande resultat som glasull. Skumglas har 9,5 % högre klimatpåverkan jämfört med cellplasten i grunden. När det gäller valet av isoleringsmaterial påverkar det klimatdeklarationen genom att förändra klimatpåverkan. Påverkan härstammar från en kombination av klimatpåverkan per enhet och mängden material som används i byggnaden. Mängden material beror delvis på isoleringsmaterialets värmekonduktivitet (λ-värde). Klimatdeklarationen visar en begränsad bild av en byggnads miljöpåverkan under en begränsad del av dess livscykel. Därför rekommenderar vi att ytterligare livscykelstadier och miljöindikatorer ingår i klimatdeklarationen i framtiden, för att undvika suboptimeringar och oavsiktliga problembyten.

Despite the recent development in PLA and PLGA based medical devices, there are still needs to further improve the mechanical performance of bioresorbable medical implants and their bioactivity. This is normally done by optimizing the filler compositions in selected groups ofbiodegradable polymer matrices. In this study, the effects of various filler levels on mechanical strength and thermal properties of PLA and PLGA composites were investigated. Composites containing different dosage of osteoconductive HAp with various particles size (0-5μm, 0-50 μm, nano size), β-TCP, bioactive glass and biodegradable Poly-L-lactide and Polylactide-glycolic acid was manufactured with melt blending, using a twin-screw extruder.The samples were investigated by Differential Scanning Calorimetry (DSC), thermo gravimetric analysis (TGA), Scanning Electron Microscopy (SEM), viscometer, three points bending machine, and Optical Microscopy (OM). The Extruder produced a porous profile. The result from TGA and SEM indicated that there was homogenous filler dispersion in the matrix after compounding.The result from DSC and Viscometer shows that there was some degradation duringcompounding. Mechanical properties of composites were modified by adding filler to matrix. The addition of Bioactive glass, as a filler, increases the degradation of the polymer matrix. The best filler that was applied is 0-5μm and nano HAp. Also in in-vitro degradation part of this thesis work, the effects of calcium phosphate materialsare investigated on degradation process.

Gemlike objects are a nearly ubiquitous phenomenon in the medium of glass, although culturally specific studies remain scarce. This dissertation considers the production of such works in the early medieval period, primarily in association with Abbasid rule. The first half attends to several accessory issues, including glass-related terminology, glass-coloring treatises, the lives of glassworkers, gemstone connoisseurship, and the legal status of such products. These demonstrate a range of coexisting attitudes, including the desirability of such works for their own sake rather than as surreptitious substitutes for “true” gemstones. The second half focuses on an exemplary object, an opaque turquoise glass bowl from the Treasury of San Marco in Venice, which I propose was produced in Baghdad for the caliph al-Mutawakkil just after the year 850. I then consider this work’s changing reception from late medieval Venice to modern scholarship, including ways in which “correct” interpretations of its material and/or origin have been repeatedly supplanted by false leads. The fundamental argument is that gemlike vessels like the San Marco turquoise were not deceptive stand-ins but rather intended to exercise complex discursive practices, both political and connoisseurial in nature, a function that ultimately remains in effect today.

Amorphous alloys possess attractive combinations of mechanical properties (high elastic limit, ~2%, high fracture toughness, 20-50 MPa.m1/2, etc.) and exhibit mechanical behavior that is different, in many ways, from that of the crystalline metals and alloys. However, fundamental understanding of the deformation and fracture mechanisms in amorphous alloys, which would allow for design of better metallic glasses, has not been established on a firm footing yet. The objective of this work is to understand the deformation and fracture mechanisms of amorphous materials at various length scales and make connections with the macroscopic properties of glasses. Various experimental techniques were employed to study the macroscopic behavior and atomistic simulations were conducted to understand the mechanisms at the nano level. Towards achieving these objectives, we first study the toughness of a Zr-based bulk metallic glass (BMG), Vitreloy-1, as a function of the free volume, which was varied by recourse to structural relaxation of the BMG through sub-Tg annealing treatment. Both isothermal annealing at 500 K (0.8Tg) for up to 24 h and isochronal annealing for 24 h in the temperature range of 130 K (0.65Tg) to 530 K (0.85Tg) were conducted and the impact toughness, Γ, values were measured. Results show severe embrittlement, with losses of up to 90% in Γ, with annealing. The variation in Γ with annealing time, ta, was found to be similar to that observed in the enthalpy change at the glass transition, ΔH, with ta, indicating that the reduction of free volume due to annealing is the primary mechanism responsible for the loss in Γ with annealing. Having established the connection between sub-atomic length scales (free volume) and macroscopic response (toughness), we investigated further the affects of relaxation on intermediate length scale behavior, namely deformation induced by shear bands, by employing instrumented indentation techniques. While the Vickers nano-indentation response of the as-cast and annealed glasses do not show any significant difference, spherical indentation response shows reduced shear band activity in the annealed BMG. Further, relatively high indentation strain was observed to be necessary for shear band initiation in the annealed glass, implying an increased resistance for the nucleation of shear bands when the BMG is annealed. In the absence of microstructural features that allow for establishment of correlation between properties and the structure, we resort to atomistic modeling to gain further understanding of the deformation mechanisms in amorphous alloys. In particular, we focus on the micromechanisms of strain accommodation including crystallization and void formation during inelastic deformation of glasses. Molecular dynamics simulations on a single component system with Lennard-Jones-like atoms suggest that a softer short range interaction between atoms favors crystallization. Compressive hydrostatic strain in the presence of a shear strain promotes crystallization whereas a tensile hydrostatic strain was found to induce voids. The deformation subsequent to the onset of crystallization includes partial re-amorphization and recrystallization, suggesting important mechanisms of plastic deformation in glasses. Next, a study of deformation induced crystallization is conducted on two component amorphous alloys through atomistic simulations. The resistance of a binary glass to deformation-induced-crystallization (deformation stability) is found to increase with increasing atomic size ratio. A new parameter called “atomic stiffness” (defined by the curvature of the inter-atomic potential at the equilibrium separation distance) is introduced and examined for its role on deformation stability. The deformation stability of binary glasses is found to increase with increasing atomic stiffness. For a given composition, the internal energies of binary crystals and glasses are compared and it is found that the energy of glass remains approximately constant for a wide range of atomic size ratios unlike crystals in which the energy increases with increasing atomic size ratio. This study uncovers the similarities between deformation and thermal stabilities of glasses and suggests new parameters for predicting highly stable glass compositions.

Amorphous alloys possess attractive combinations of mechanical properties (high elastic limit, ~2%, high fracture toughness, 20-50 MPa.m1/2, etc.) and exhibit mechanical behavior that is different, in many ways, from that of the crystalline metals and alloys. However, fundamental understanding of the deformation and fracture mechanisms in amorphous alloys, which would allow for design of better metallic glasses, has not been established on a firm footing yet. The objective of this work is to understand the deformation and fracture mechanisms of amorphous materials at various length scales and make connections with the macroscopic properties of glasses. Various experimental techniques were employed to study the macroscopic behavior and atomistic simulations were conducted to understand the mechanisms at the nano level. Towards achieving these objectives, we first study the toughness of a Zr-based bulk metallic glass (BMG), Vitreloy-1, as a function of the free volume, which was varied by recourse to structural relaxation of the BMG through sub-Tg annealing treatment. Both isothermal annealing at 500 K (0.8Tg) for up to 24 h and isochronal annealing for 24 h in the temperature range of 130 K (0.65Tg) to 530 K (0.85Tg) were conducted and the impact toughness, Γ, values were measured. Results show severe embrittlement, with losses of up to 90% in Γ, with annealing. The variation in Γ with annealing time, ta, was found to be similar to that observed in the enthalpy change at the glass transition, ΔH, with ta, indicating that the reduction of free volume due to annealing is the primary mechanism responsible for the loss in Γ with annealing. Having established the connection between sub-atomic length scales (free volume) and macroscopic response (toughness), we investigated further the affects of relaxation on intermediate length scale behavior, namely deformation induced by shear bands, by employing instrumented indentation techniques. While the Vickers nano-indentation response of the as-cast and annealed glasses do not show any significant difference, spherical indentation response shows reduced shear band activity in the annealed BMG. Further, relatively high indentation strain was observed to be necessary for shear band initiation in the annealed glass, implying an increased resistance for the nucleation of shear bands when the BMG is annealed. In the absence of microstructural features that allow for establishment of correlation between properties and the structure, we resort to atomistic modeling to gain further understanding of the deformation mechanisms in amorphous alloys. In particular, we focus on the micromechanisms of strain accommodation including crystallization and void formation during inelastic deformation of glasses. Molecular dynamics simulations on a single component system with Lennard-Jones-like atoms suggest that a softer short range interaction between atoms favors crystallization. Compressive hydrostatic strain in the presence of a shear strain promotes crystallization whereas a tensile hydrostatic strain was found to induce voids. The deformation subsequent to the onset of crystallization includes partial re-amorphization and recrystallization, suggesting important mechanisms of plastic deformation in glasses. Next, a study of deformation induced crystallization is conducted on two component amorphous alloys through atomistic simulations. The resistance of a binary glass to deformation-induced-crystallization (deformation stability) is found to increase with increasing atomic size ratio. A new parameter called “atomic stiffness” (defined by the curvature of the inter-atomic potential at the equilibrium separation distance) is introduced and examined for its role on deformation stability. The deformation stability of binary glasses is found to increase with increasing atomic stiffness. For a given composition, the internal energies of binary crystals and glasses are compared and it is found that the energy of glass remains approximately constant for a wide range of atomic size ratios unlike crystals in which the energy increases with increasing atomic size ratio. This study uncovers the similarities between deformation and thermal stabilities of glasses and suggests new parameters for predicting highly stable glass compositions.

Bulk metallic glasses (BMGs) possess very attractive mechanical properties like high yield strength (~ 2 GPa), high elastic strain limit (2 %), and good corrosion resistance. BMGs display fracture toughness values (in mode I) which are ranging from being extremely brittle (less than 5 MPa√ ) to very tough (150 MPa√ ). Further the fracture toughness of BMGs is highly sensitive to intrinsic and extrinsic factors like composition, temperature of testing, thermal history, impurity content, sample size, fracture testing mode and crack tip dimensions. Thorough understanding of the above issues is essential for their safe deployment in structural applications. Hence, finite element and experimental studies on fracture behavior of BMGs are undertaken in this thesis. In order to understand the effect of testing temperature on the fracture toughness and ductility of the BMG a temperature dependence study is undertaken. Complimentary finite element analyses were utilized to convert the critical load to fracture toughness. Temperature dependence mode I fracture toughness and three point bend experiments study reveals that toughness and ductility minimum occurs at same temperature range which is about 65% of glass transition temperature. These observations are rationalized with the aid of notch plastic deformation and post mortem fractographic characterization and in terms of the influence of temperature on factors such as the number of shear bands, the barrier for their conversion into shear cracks, and hydrostatic stress gradient ahead of the notch tip. This study highlights the sensitive nature of BMGs fracture toughness, even when they are nominally ductile, to temperature. It is well recognized qualitatively, that shear band mediated plasticity ahead of crack or notch tips is the reason for the high fracture toughness of 'ductile' bulk metallic glasses (BMGs), quantitative connection between those two material properties is yet to be established. In an attempt to study this, we examine if mode I fracture initiation toughness, iii KIc, of a number of BMGs can be related to the shear band number, Ni, which is a discretized measure of plasticity in MGs, around spherical indentation impressions that are made to a fracture mechanism based predetermined indentation strain. Results show that KIc scales with (Ni)3/2. Then, the relation between the shear band density in the notch tip plastic zone, Nn, and KIc is examined, which shows that a power law: KIc (Nn)1/2, captures the data reported in literature for a number of BMGs. This result confirms that it is indeed the notch tip plasticity that determines KIc of BMGs. The power law exponent of 0.5 is rationalized by recourse to elasto-plastic fracture mechanics. Possible connections between Ni and Nn, ways of enhancing the latter so as to increase KIc, and the central role played by the relative density of MGs in determining both elastic, plastic, and fracture responses are discussed. Finally, we studied notched pure torsion as well as tension-torsion experiments, coupled with FEA, on notched Zr-based BMG bars. The notch tip deformation and fracture initiation processes is studied in detail. Further, we have compared the deformation and fracture responses of shallow and sharp notched specimens. It helped in understanding the effect of change in the notch acuity on shear band deformation patterns as well as effect on the hydrostatic stress distributions at the notch root. A comparison of the fracture toughness values in all the three modes and mixed mode (I and III) is carried out. Results show that mode II fracture toughness is lower in comparison of mode I and mode III. Fracture toughness obtained from mode II tests may serve as a conservative baseline for using BMG in designing structural applications.

碩士
國立臺北科技大學
化學工程與生物科技系化學工程碩士班（碩士在職專班）
105
The PTFE-Glass Fabric Composite produced in this study can use to remove PM2.5 in high temperature emission gas in industry. The experiment is divided into two parts; the first one is to combine expanded microporous Polytetrafluoroethylene (ePTFE) film with PTFE-dipped glass fabric in a single-stage wet process that can greatly increase the production efficiency in current industry. Two types of glass fabric dip with different solid contents of PTFE suspension. The PTFE-dipped glass fabric then affix with ePTFE film on its one side under suitable operation conditions to obtain PTFE-glass fabric composite with appropriate bonding strength, pore size distribution and air permeability for filtration bag. The filtration bag with 15% PTFE solid content produced by the single-stage wet process has 700g of bonding strength, lower than 1µm of pore diameter, and 2 cm³/cm²/s of air permeability. These properties achieve the commercial product standard. The second part in this study is to prepare microporous thin film, instead of ePTFE, and coated on the surface of PTFE-glass fabric. In this part, an emulsion solution of PTFE with micro-sized micelles by using appropriate plasticizer was prepared first, and then coated on the above-mentioned PTFE-glass fabric by dip process. Finally, a thin film with microporous formed on the surface of the PTFE-glass fabric after drying and sintering. The microporous film contained about 2.5µm of pore diameter, but the air permeability is not comparable to the PTFE-glass fiber composite made of ePTFE film. This problem can be solved by adjusting the coating process and the weaving patterns of fabric.

Nemertodermatida is a group of microscopic marine worm-like animals that live as part of the marine meiofauna in sandy or muddy sediments; one species lives commensally in a holothurian. These benthic worms were thought to disperse passively with ocean currents, resulting in little speciation and thus wide or even cosmopolitan distributions. Individuals occur in low abundance and have few light microscopically available characters, which altogether may explain why only eight species had been described between the discovery of the taxon in 1930 and this thesis. We used molecular methods to address the diversity and phylogeny of this group for the first time. In a study of two nominal species with samples from all around the world, a high degree of cryptic speciation was discovered and several new species described. Diagnoses were based on molecular data complemented by morphological characters, where available. Given the patchy geographical record it can be assumed that the majority of the biodiversity of Nemertodermatida is yet to be described. A phylogenetic study including all but three known species revealed a deep divergence between the two families of Nemertodermatida but non-monophyly of the taxon was rejected by an Approximately Unbiased test. Confocal laser scanning microscopic studies of several species show that the pattern of the body-wall musculature and the nervous system are specific for different genera. The muscular system of all species consists of a basic orthogonal grid with specific diagonal musculature and specialized muscles associated with body openings. The mouth appears to be transient feature in Nemertodermatida, developing only after hatching and being reduced again in mature worms. The nervous system is highly variable with very different ground patterns between the genera, such as an epidermal net, a centralized neuropile or a commissural brain.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4. Manuscript.