Dissertations / Theses on the topic 'Earth-based material'

In Eskilstuna and Sweden in general the level of reuse of surplus material containing soils and rocks from excavation is low. In this report the potential for increasing the reuse of excavated material in Eskilstuna by using a web-based earth information database has been examined. The purpose of a web-based earth information database is to connect those who have surplus material with those who need material for a fast and simple transaction. The intention is to give Eskilstuna a more environmentally and economically efficient handling of surplus material by increasing the level of reuse and thereby reducing the amount of surplus material that is wasted and emissions given off to the atmosphere during transportation. The potential has been examined in two different ways, by tracing information about a number of projects to see if excavated material driven to the dump could have been used in another project and by interviewing eight of the work leaders active in Eskilstuna. The potential has been determined to be low based mostly on the interviews and on the current legislation. Although many of the work leaders were positive to use an earth information database there is too much speaking against it. For example the contractor who wants to use another contractor’s surplus material has to apply to the local authority six weeks ahead. In the work place the limited time and space, which are the two most important factors for being able to reuse material on site, doesn’t allow the paperwork to take so long time. But it’s not impossible to launch a web-based earth information database in Eskilstuna and recommendations has been given for important considerations if one is to be initiated.

Lergjord is a thesis that puts emphasis on the possibility of innovation by using local biobased material in the building industry of Skåne in Sweden. The thesis examines if rammed earth can be used in the implementation of LFM30 (Translated into English: Local Sustainable Goals in Malmö by 2030). By use of qualitative research methods, views on rammed earth as a building technique was explored by three stakeholders. This research has concluded if rammed earth is possible in Skåne as a conventional material in the future. We (Ludvig Dovberg and Tobias Löfgren) have examined the practical aspect of rammed earth on Urban Living Lab in the municipality of Lund by the use of local clay material from excavation for an expansion of a new railway between Malmö and Lund in collaboration with Trafikverket. This thesis concludes that rammed earth is feasible with clay from the excavation masses through project LERGJORD. Also, due to the vast quantity of it the resource might be useful for future rammed earth projects in Skåne. However, the building technique itself has some major drawbacks such as time-consumption and the knowledge gap is easily addressed. Although, there has been a development of a pre-fabrication concept of the building technique in Germany since the late 1990s, that could be a solution to the problem. The thesis also concludes that  higher education and research is compulsory to establish a knowledge base for architects to work by. The case study showcased that a standardization of the material is needed to prevent vast material testing before being accepted for construction, like the Lehmbau-praxis in Germany. According to the material’s low impact in CO₂-emission and circularity this resourceful extraction could be of interest by the members of LFM30 to implement in the building industry of Skåne.
Lergjord är ett arbete som undersöker möjligheten till innovation genom att utnyttja lokala biobaserade material i Skåne i Sverige. Arbetet undersöker om stampad jordbyggnad kan användas för att genomföra de Lokala Färdplansmålen som Malmö Stad sätter fram till år 2030 (förk. LFM30). Genom kvalitativa forskningsmetoder undersöktes stampad lerjord som byggnadsteknik hos tre intressenter. Studien har sammanfattat möjligheten om hur stampad lerjord i Skåne kan bli ett konventionellt byggmaterial i framtiden. Vi (Ludvig Dovberg och Tobias Löfgren) har utvärderat den praktiska aspekten i stampad lerjord på Urban Living Lab i Lund med användandet av lokal lerjord från utgrävningar av tillbyggnation för järnvägsspår mellan Malmö och Lund i samarbete med Trafikverket. Arbetet visar att stampjordstekniken är möjlig med utvunnen lera från schaktmassorna mellan Lund och Malmö med hänvisning till projekt LERGJORD. Med tanke på den stora kvantitet av lera som finns kan denna utvinning vara användbar för andra projekt i Skåne. Hursomhelst, byggtekniken besitter på utmaningar såsom tidskrav och kunskapsluckan är tämligen lätt att adressera. Trots det, har ett prefabriceringskoncept inom byggtekniken utvecklats sedan slutet på 1990-talet i Tyskland, som kan vara en lösning på problemet. Arbetet tyder också på att högre utbildning och forskning krävs för att etablera en kunskapsbas som arkitekter kan arbeta vidare på. Fallstudien visar på att en standardisering av materialet krävs för att undvika långa och omständliga materialtester innan godkännande för konstruktion, likt Lehmbau-lagstiftningen i Tyskland. Materialets låga klimatpåverkan och cirkularitet gör det relevant för LMF30’s medlemmar att se vidare på alternativet för implementering i den skånska byggindustrin.

Au cours des dernières années, l'électronique à base d’oxydes métalliques a attiré de plus en plus d'attention au sein de la recherche, principalement grâce à leur potentiel en termes de réduction de coûts ainsi que la possibilité de développer une électronique transparente. Il existe plusieurs applications potentielles concernant les oxydes métalliques : le photovoltaïque, les transistors à couche mince et la photo-électrochimie. Il existe plusieurs oxydes métalliques de type n avec d'excellentes propriétés électroniques, telles que l'oxyde de zinc dopé à Al. Mais la mise au point de dispositifs entièrement à base d’oxydes métalliques est largement entravée par les mauvaises propriétés électroniques des oxydes de type p jusqu'à présent étudiés. Par conséquent, il est nécessaire de développer des matériaux semi-conducteurs d'oxyde métallique de type p présentant de meilleures propriétés électriques.Dans cette thèse, l'optimisation du dépôt de films minces de Cu2O a été effectuée par MOCVD assisté par aérosol (AA-MOCVD). Par conséquent, des films de Cu2O homogènes et de très forte cristallinité ont été déposés à basse température (environ 335 °C) sans contamination détectable de carbone. De plus, grâce à l'incorporation de l'humidité durant les dépôts, la taille des grains et l'orientation des films Cu2O peuvent être modulées, ainsi des films de Cu2O avec une texturation (111) et une taille de grains > 300 nm ont été obtenus. Pour les films Cu2O optimisés, la mobilité peut atteindre un maximum de 15 cm2 / V.s avec une concentration de porteur de l'ordre de 1015 cm-3. Enfin, un excellent comportement diode a été observé en combinant les films de Cu2O optimisés avec du ZnO, obtenant un rapport on/off supérieur à 104.En raison de l'incompatibilité entre la fenêtre de stabilité thermique associée à AgCuO2 et les températures nécessaires pour déposer des composés Ag et Cu par CVD avec les précurseurs utilisés, le dépôt direct d'AgCuO2 n'a pas pu être obtenu. Ainsi, des techniques de revêtement couche mince à base de solution ont été adoptées pour le dépôt de film AgCuO2. En particulier, la méthode SILAR a permis le dépôt de films minces d’AgCuO2. Grâce à une couche d’amorce sur substrat de verre appropriée, des couches d'AgCuO2 denses et continues ont été revêtues, avec une valeur RMS minimale de 8 nm. Les films d’AgCuO2 déposés avaient une phase presque pure. Les propriétés optiques et de transport des films minces AgCuO2 ont donc été analysées pour la première fois. Les mesures de transmittance ont confirmé la faible largeur de bande interdite prédite d’AgCuO2 (1,2 eV), tandis que grâce à l’utilisation de la formule de Tauc, nous avons constaté que ce matériau est plus susceptible d'avoir une bande interdite directe, en accord avec les calculs DFT publiés. Grâce aux mesures de l'effet Hall, les films AgCuO2 déposés ont été confirmés comme étant de type p. La plus faible résistivité atteinte est de 0,2 Ω.cm. En outre, ces films avaient une densité de porteurs de charge de l'ordre de 1017 cm-3 et la meilleure mobilité atteinte était de 24 cm2 / V.s. En comparaison avec les composés de type p de delafossite précédemment rapportés (M, Al, Cr, Ga, etc.), ce matériau présente la plus petite largeur de bande interdite (intéressant notamment pour l'application photovoltaïque) et une conductivité assez élevée. La caractéristique la plus intéressante est que le problème général de la faible mobilité des transporteurs dans ces composés delafossite a été résolu dans cet AgCuO2, grâce à sa structure électronique mixte et à la délocalisation des charges. Ainsi, ces résultats de caractérisation sans précédent ouvrent la voie à l'utilisation de films AgCuO2 dans des dispositifs fonctionnels
In recent years, metal oxide electronics has attracted more and more attention in research, mainly thanks to their potential lower cost and the possibility they offer to develop transparent electronics. There are several potential applications concerned with metal oxides including photovoltaics, thin film transistors and photo-electrochemistry. There are several n-type metal oxides with excellent electronic properties being well developed, such as Al doped zinc oxide. But the fabrication of devices fully made with metal oxides is largely impeded by the poor electronic properties of the p-type oxides so far studied. Therefore, there is the need for developing p-type metal oxide semiconducting materials with better electrical properties.In this thesis, the optimization of pure Cu2O thin film deposition was conducted using Aerosol Assisted MOCVD (AA-MOCVD). As a result, homogenous Cu2O films were deposited at low temperature (about 335 °C) without detectable amount of carbon contamination with high crystallinity. In addition, by incorporation of humidity during the deposition, particle size and the orientation of the Cu2O films could be tuned, thus Cu2O films with (111) textured large grain sizes (> 300 nm) were achieved. For optimized Cu2O films, the mobility can reach a maximum of 15 cm2/V.s with carrier concentration in the order of 1015 cm-3. Lastly, an excellent diode behaviour was observed by combining the optimized Cu2O films with ZnO, obtaining an on-off ratio exceeding 104.Besides the Cu2O optimization, the deposition of AgCuO2 by MOCVD was also tackled. In order to do so, the deposition of silver and silver oxide thin films was previously optimized. For that, two new silver precursors, namely, Ag(hfac)phenanthroline and Ag(hfac)triglyme were synthesized and fully characterized. High quality Ag coatings could be obtained with both precursors. Silver oxide films were obtained through electrochemical oxidation and oxygen plasma treatment of pre-deposited Ag coatings.Due to the incompatibility between the thermal AgCuO2 stability window and the temperatures needed to deposit Ag and Cu compounds by CVD with the precursors used, the direct deposition of AgCuO2 could not be obtained. Thus, solution based thin film coating techniques were adopted for AgCuO2 film deposition. In particular, Successive Ionic Layer Adsorption and Reaction (SILAR) allowed the deposition of AgCuO2 thin films. Using a proper seed layer on glass, dense and continuous AgCuO2 films were coated, with minimum RMS value of 8 nm. The deposited AgCuO2 films had almost pure phase. The optical and transport properties of AgCuO2 thin films were thus carried out for the first time. Transmittance measurements confirmed the predicted low bandgap of AgCuO2 (1.2 eV), while by using the Tauc formula, we found that this material is more likely to have a direct bandgap, in agreement with published DFT calculations. Thanks to Hall Effect measurements, the deposited AgCuO2 films were confirmed to be p-type. The lowest resistivity achieved was 0.2 Ω.cm. In addition, those films had carrier density in the order of 1017 cm-3 and the best mobility achieved was 24 cm2/V.s. Comparing with the previously reported CuMO2 (M= Al, Cr, Ga etc) delafossite p-type compounds, this material has shown the lowest bandgap (appropriate for photovoltaic application) and rather high conductivity. The most interesting characteristic is that the general problem of low carrier mobility in those delafossite compounds has been solved in this AgCuO2, thanks to its mixed-valence electronic structure and charges delocalization. Thus, those unprecedented characterization results pave the way for using AgCuO2 films in functional devices

Green and renewable energy materials have attracted great interest because of the soaring price of fossil energy and global warming. Among them, lithium secondary batteries are the key components of portable electronic devices as well as hybrid and electric cars and have been studied for over 30 years. Although in current commercial Li rechargeable batteries liquid and polymer electrolyte are the common electrolyte materials, safety issues are still of concern which therefore leads to an increasing interest in technological improvement and a demand for new materials for all solid state Li rechargeable batteries. In this project, various Li rare earth-oxide based compositions containing Nb, transition metal or trivalent cations were studied in order to find materials for possible Li-ion secondary battery applications. Stoichiometric phase-pure garnet, LisLa3Nb2012, was found to be difficult to synthesise due to the loss of volatile LhO. The covering blanket method involving careful heat profiles to reduce the possibilities of lithia loss during heating has been used in the present study of selected compositions in the Li20-La203-Nb20s system; a solid solution, Lis+xLa3Nbz0I2-osx, has been found. Electrical properties were measured by impedance spectroscopy and samples showed intrinsic Li ionic conductivity, - 10-6 Scm', at room temperature. Several new lithium Nd-based ternary oxides containing also Fe or Rh have been reported, but there was considerable disagreement over the possible stoichiometry of these phases. A detailed study of the ternary phase diagram of the LhO-Nd203-Fe203 system has been carried out with the initial objective to determine the stoichiometry of the previously reported ternary phase. A revised stoichiometry, LillNdlSFe4039, which differs from all previously claimed formulae, is proposed along with a revised phase diagram of the LizO-Nd203-Fe203 system. The crystal structure of this revised ternary phase has been studied using a combination of X- ray and neutron diffraction methods. It is primitive cubic, a = - 12 A, space group Pm "3 n. The structure is complex and can be described as comprising four < III > face-sharing polyhedra with alternating Li06 trigonal prisms and Fe06 octahedra intercepting at the origin and body-centre of the unit cell within an Nd-O framework. Face-sharing trigonal prismatic sites occupied by u: form octagon-like polyhedral coordination; with partially occupancy in one of those two trigonal prismatic sites these face-sharing polyhedra provide a possible short distance Li ion conduction pathway. Structural studies indicate that because the formula unit contains 39 oxygens, Fe is present in a mixture of 3+ and 4+ oxidation states. However, the valence state of Fe is variable, from Fe2+ only to a mixture of Fe 3+/4+, depending on different heat profiles; electrical properties of samples also reveal a change from semiconducting to insulating behaviours using impedance spectroscopy (IS). Using the same methodology, four new phases, Li11NdlsC04039, LiIINdlsAI40385, Li\JSmlSFe4039 and LiIISmISC04039, have been found in a survey of compound formation, Li\JRE1sM4039. Two ternary phase diagrams, LbO-Nd203-Ah03 and Li-Nd-Co-O system, are presented here; the Li20-Nd203-Ah03 system reveals a similar ternary phase diagram to that of Fe analogue system but a new ternary phase, LiCoNd4O8, and a solid solution, Lill-xNdlsC04039-o.5x have been found in the Co system. The crystal structures of those four new phases have been determined and are similar to that of Li11NdlsFe4039. Apart from LilINdlsAl403S5, which shows Li ionic conductivity, all the phases show modest electronic conductivity by IS. Two new phases, LiCoNd4O8 and LiNiNd40g, have been found in a survey of compound formation, LiMRE40s, after heating under suitable conditions. Rietveld refinement of the LiNiNd40s crystal structure was carried out using neutron powder diffraction; it shows that the crystal structure might have a supercell based upon the K2NiF 4 structural model. The electrical properties of these two new phases reveal very similar electrical characteristics, with electronic conductivity and constriction effect in the ceramics. During the study of compound formation, LiMRE40s, an X-ray pattern similar to that of the previously reported phase, LioI4Cuo86Nd204-o, appeared in the attempted synthesis of several LiCuRE40s compositions. In the present study, two new phases, Lio.14Cuos6Pr204-o and Lio.14Cuos6Sm204-8, were prepared. Rietveld refinements of the crystal structures are in agreement with the reported structural model. Electrical properties of samples revealed a very conducting behaviour which can be varied depending on heating conditions.

The NaNbO3-BaTiO3 (NNBT) solid solution was studied as a novel RE-free material for MLCC applications. Relaxor behaviour was found for NaNbO3 (NN)-concentrations as low as 2 mol%. The solid solution changes its behaviour with increasing NN-concentration from ferroelectric, to mixed ferroelectric-relaxor, to relaxor, to mixed behaviour again and finally ferroelectric. Broad permittivity profiles could therefore be obtained for a number of compositions with a wide range of Tmax, Na0.9Ba0.1Nb0.9Ti0.1O3 (90NNBT) possessed an industry standard (X7R) of TCC = ±15 % from -55 to 125 °C with low dielectric loss and a RT permittivity of ~ 800. Bilayers were then used to imitate CS microstructures and improve TCC. Optimisation of ‘core’-like material, i.e. BT, and a ‘shell’-like material, i.e. 2.5NNBT, in a bilayer at a volume ratio of 0.67 2.5NNBT with 0.33 BT resulted in a TCC of ±6% over the temperature range of 25 to 125 °C whilst maintaining a RT permittivity ~3000 and low dielectric loss. Utilising simulations of bilayer permittivity profiles reduced the number of trial and error compositions required to achieve permittivity and TCC targets. One limitation, however, was the interfaces that form, as they add an additional unaccounted component to the series model used. Their impact was reduced through careful processing. BT-2.5NNBT-90NNBT trilayers resulted in extended temperature range for low TCC applications, pushing the upper temperature up to over 150 °C. 0.33(BT)-0.33(2.5NNBT)-0.33(90NNBT) maintains a TCC of ±15 % to over 150 °C, with RT permittivity values above 100 and low dielectric loss. Adapted ternary phase diagrams were used to identify compositions that led to lower TCCs. Several important observations were drawn from the bi- and trilayer systems which suggested that that low TCC capacitors may be developed for any temperature range by the following protocols: (i) choose a temperature range, i.e. 100-200 °C; (ii) choose a material that possesses a Tmax of around 100 °C; (iii) choose a material with Tmax a little above 200 °C and (iv) choose a third material that possesses a Tmax that sits in the middle of the previous two materials, or has a broad shoulder that spans the gap between the other two Tmaxs. The number of materials are varied depending on the required temperature range. In general, the lowest number of materials that gives the required TCC should be chosen. This concept was tested for the creation of a temperature stable plateau 7 between 100 and 200 °C by a BT-85NNBT-90NNBT trilayer. The permittivity-temperature profile shows a plateau between ~100 and ~200 °C with permittivity changes of ~ ±10 % in that temperature range. Industrial MLCC prototypes based on the hypotheses from this work were made by AVX Ltd in Coleraine. The devices possessed comparable TCC and better lifetimes compared with equivalent commercial products.

Materials for energy applications are of great importance for a sustainable future society. Among these, stronger, lighter and more efficient magnetic materials will be able to aid mankind in many applications for energy conversion, for example generators for energy production, electric vehicles and magnetic refrigerators. Another requirement for the materials is that they should be made from cheap and abundant elements. For these reasons temperature induced magnetic transitions for three materials were studied in this work; one for permanent magnet applications and two magnetocaloric materials. Fe5SiB2 has a high Curie temperature and orders ferromagnetically at 760 K, providing possible application as a permanent magnet material. The ordering of the magnetic moments were studied and found to be aligned along the tetragonal c-axis and Fe5SiB2 undergoes a spin transition on cooling through a transition temperature (172 K), where the spins reorient along the a-axis in an easy plane. AlFe2B2 orders ferromagnetically at 285 K, making it a candidate for the active material in a magnetic refrigerator. The order of the magnetic transition has been studied as well as the magnetic structure. It was found that the magnetic moments are aligned along the crystallographic a-axis and that the magnetic transition is of second order. FeMnP0.75Si0.25 undergoes a first order magnetic transition around 200 K and the transition temperatures on cooling are different for the first cooling/heating cycle than for following cycles. This so called ”virgin effect” has been studied and found to originate from an irreversible structure change on the first cooling cycle through the ferromagnetic transition temperature.

Magnetic, magnetocaloric, magnetotransport and magnetoelastic properties of Ni-Mn-X (X = In, and Ga) Heusler alloys and La-Fe-Si based rare earth compounds have been synthesized and investigated by x-ray diffraction, magnetization, strain, and electrical resistivity measurements. The phase transitions, magnetic, magnetocaloric, magnetotransport and magnetoelastic properties strongly depend on the composition of these systems. In Ni50Mn50-xInx with x = 13.5, magnetocaloric and magnetotransport properties associated with the paramagnetic martensitic to paramagnetic austenitic transformation were studied. It was shown that magnetic entropy changes (SM) and magnetoresistance (MR) associated with this transformation are larger and the hysteresis effect is significantly lower when compared to that associated with paramagnetic-ferromagnetic transitions or ferromagnetic-antiferromagnetic/paramagnetic transitions in other systems. The Hall resistivity and the Hall angle shows unusual behavior in the vicinity of the martensitic phase transition for Ni50Mn50-xInx with x = 15.2. The observed Hall resistivity and Hall angle are 50 μ*cm and , respectively. It was observed that the presence of Ge, Al and Si atoms on the In sites strongly affects the crystal structure, and the electric and magnetic behaviors of Ni50Mn35In15. It was found that the partial substitution of In atoms by Si in Ni50Mn35In15 results in an increase in the magnetocaloric effect, exchange bias and shape memory effect. In Ni50Mn35In15-xSix, the peak values of positive SM for magnetic field changes H = 5 T were found to depend on composition and vary from 82 Jkg-1K-1 for x = 1 (at T = 275 K) to 124 Jkg-1K-1 for x = 3 (at T = 239 K). The partial substitution of Ni by Co in Ni50Mn35In15 significantly improves the magnetocaloric effect and MR in the vicinity of martensitic transition. In addition, significantly large inverse SM and MR were observed at the inverse martensitic phase transitions of the Ga-based magnetic shape memory Heusler alloys Ni50-xCoxMn32-yFeyGa18. The phase transition temperatures and magnetic properties were found to be correlated with the degree of tetragonal distortion in these samples. In LaFe11.57Si1.43Bx the crystal cell parameters and Curie temperatures were found to increase linearly with increasing B concentration up to ~ 0.1 % and 9 %, respectively. It was found that the characteristics of the magnetocaloric effect of LaFe11.57Si1.43 can be adjusted by a change in B concentration in the LaFe11.57Si1.43Bx system. A study of the influence of a small substitution of Ni, Cu, Cr, and V for Fe in LaFe11.4Si1.6 revealed that the magnetic, magnetocaloric, and magnetovolume coupling constant is related to an increase in the average Fe-Fe interatomic distances, leading to a change in the d-d exchange interaction.

Doutoramento em Ciência e Engenharia dos Materiais
The planar design of solid oxide fuel cell (SOFC) is the most promising one due to its easier fabrication, improved performance and relatively high power density. In planar SOFCs and other solid-electrolyte devices, gas-tight seals must be formed along the edges of each cell and between the stack and gas manifolds. Glass and glass-ceramic (GC), in particular alkaline-earth alumino silicate based glasses and GCs, are becoming the most promising materials for gas-tight sealing applications in SOFCs. Besides the development of new glass-based materials, new additional concepts are required to overcome the challenges being faced by the currently existing sealant technology. The present work deals with the development of glasses- and GCs-based materials to be used as a sealants for SOFCs and other electrochemical functional applications. In this pursuit, various glasses and GCs in the field of diopside crystalline materials have been synthesized and characterized by a wide array of techniques. All the glasses were prepared by melt-quenching technique while GCs were produced by sintering of glass powder compacts at the temperature ranges from 800−900 ºC for 1−1000 h. Furthermore, the influence of various ionic substitutions, especially SrO for CaO, and Ln2O3 (Ln=La, Nd, Gd, and Yb), for MgO + SiO2 in Al-containing diopside on the structure, sintering and crystallization behaviour of glasses and properties of resultant GCs has been investigated, in relevance with final application as sealants in SOFC. From the results obtained in the study of diopside-based glasses, a bilayered concept of GC sealant is proposed to overcome the challenges being faced by (SOFCs). The systems designated as Gd−0.3 (in mol%: 20.62MgO−18.05CaO−7.74SrO−46.40SiO2−1.29Al2O3 − 2.04 B2O3−3.87Gd2O3) and Sr−0.3 (in mol%: 24.54 MgO−14.73 CaO−7.36 SrO−0.55 BaO−47.73 SiO2−1.23 Al2O3−1.23 La2O3−1.79 B2O3−0.84 NiO) have been utilized to realize the bi-layer concept. Both GCs exhibit similar thermal properties, while differing in their amorphous fractions, revealed excellent thermal stability along a period of 1,000 h. They also bonded well to the metallic interconnect (Crofer22APU) and 8 mol% yttrium stabilized zirconium (8YSZ) ceramic electrolyte without forming undesirable interfacial layers at the joints of SOFC components and GC. Two separated layers composed of glasses (Gd−0.3 and Sr−0.3) were prepared and deposited onto interconnect materials using a tape casting approach. The bi-layered GC showed good wetting and bonding ability to Crofer22APU plate, suitable thermal expansion coefficient (9.7–11.1 × 10–6 K−1), mechanical reliability, high electrical resistivity, and strong adhesion to the SOFC componets. All these features confirm the good suitability of the investigated bi-layered sealant system for SOFC applications.
A concepção planar de células de combustível de óxido sólido (SOFC) é a mais promissora devido a sua fabricação mais fácil, um melhor desempenho e uma densidade de potência relativamente elevada. Nas SOFCs planares e outros dispositivos de electrólitos sólidos são necessárias vedações estanques ao gás ao longo das arestas de cada uma das células e entre os tubos de distribuição de gás e de pilha. Materiais vítreos e vitrocerâmicos (GC), em particular com composições baseadas em aluminosilicatos alcalino-terrosos, estão entre os materiais mais promissores para aplicações de vedação à prova de gás em SOFCs. Além do desenvolvimento de novos materiais à base de vidros e vitrocerâmicos, são também necessários novos conceitos para superar os desafios enfrentados pela tecnologia selante atualmente existente. O presente trabalho visa dar um contributo nesse sentido, propondo soluções de vedação para SOFCs e outras aplicações electroquímicas. Para o efeito, foram sintetizados vários vidros e GCs à base de diópsido, os quais foram caracterizados por recurso a uma grande variedade de técnicas. Todos os vidros foram preparados por fusão, enquanto os GCs foram produzidos por sinterização (tratamento térmico) de compactos de pó de vidro nas faixas de temperatura de 800 − 900 ºC por 1 − 1000 h. Além disso, foram estudados os efeitos de diversas substituições iónicas, especialmente de CaO por SrO, e de MgO + SiO2 por Ln2O3 (Ln = La, Nd, Gd, e Yb), em composições de aluminosilicatos à base de diópsido na estrutura, sinterização e cristalização dos vidros e nas propriedades dos GCs resultantes com particular relevância para as propriedades de vedação em SOFCs. Com base nos resultados obtidos neste estudo, foi possível propor um novo conceito de selante vritrocerâmico em bi-camadas que visa ultrapassar os desafios enfrentados pelos vedantes actualmente usados em SOFCs. Os sistemas designados por Gd−0,3 (em % molar: 20,62 MgO−18,05 CaO−7,74 SrO−46,40 SiO2−1,29 Al2O3−2,04 B2O3−3,87 Gd2O3) e Sr−0,3 (em % molar: 24,54 MgO−14,73 CaO−7,36 SrO−0,55 BaO−47,73 SiO2−1,23 Al2O3−1,23 La2O3−1,79 B2O3−0,84 NiO) foram seleccionados para realizar o conceito de bi-camada. Ambos os GCs exibem propriedades térmicas semelhantes, e excelente estabilidade térmica ao longo de um período de 1.000 horas, mas diferem nas suas fracções vítreas/cristalinas. Eles revelaram também elevada aptidão para se ligarem à interconexão metálica (Crofer22APU) e ao electrólito sólido (zircónia estabilizada com 8 mol% de ítria (8YSZ) sem a formação de camadas interfaciais indesejáveis entre os diferentes componentes das SOFCs. Duas camadas separadas compostas pelos vidros (Gd−0,3 e Sr−0.3) foram preparadas e depositadas sobre as interconexões metálicas através de uma abordagem tape casting. As bi-camadas vitrocerâmicas mostram boa capacidade de molhamento e ligação à placa Crofer22APU, coeficientes de expansão térmica adequados (9,7−11,1 × 10−6 K−1), confiabilidade mecânica, elevada resistividade eléctrica, e uma forte adesão aos componentes da SOFC. Todas estas características confirmam a boa adequação do sistema selante bi-camadas investigado para aplicações em SOFCs.

Cette étude a pour objet de comparer les propriétés acoustiques, mécaniques et hygrothermiques de différents biocomposites destinée à l’isolation des bâtiments à base de granulats issus de co-produits végétaux et d’un liant à base d’argile. Nous avons d’abord analysé les matières premières afin d’obtenir d’une part la masse volumique et les propriétés thermiques et hydriques des granulats végétaux et les caractéristiques minéralogiques et gravimétriques de la terre crue sélectionnée d’autre part. L’évolution de la conductivité thermique des mélanges terre:granulats végétaux a été étudiée à différents taux d’humidité et différentes masses volumiques. D’un point de vue hydrique, les capacités de sorption/désorption de ces matériaux ont été mesurées en régime statique de même que la capacité de tampon hydrique simulant un régime dynamique. L’un des principaux intérêts de cette étude est de confirmer qu’une large gamme de co-produits végétaux produits à l’échelle locale pourrait être utilisée en tant que granulats pour l’élaboration de bétons végétaux
The purpose of this study was to compare hygrothermal acoustical and mechanical properties ot different materials based on vegetal aggregates and clay in order to characterize the performances of different biocomposites to provide building insulation solutions with a view to valorizing agricultural waste. We first analyzed the raw materials in order to get the density, thermal and hydric properties of the vegetal aggregates in one hand and the mineralogy and gravimetric data of the selected crude earth in the other hand. Thermal behavior of earth:vegetal aggregates mixes have been investigated at different humidity rates and different density ranges. Additionally, hydric properties have been measured to produce sorption and desorption curves and moisture buffer values (MBV) in one hand and capillarity of both aggregates and biocomposites on the other hand. One of the main interests of this study is to confirm that a wide range of locally produced vegetal byproducts could be used as - bioaggregates for concretes. Local biomaterials industries could therefore emerge depending on the locally available resources at country scale

Large-scale earthmoving activities make up a costly and air-polluting aspect of many construction projects and mining operations, which depend entirely on the use of heavy construction equipment. The long-term jobsites and manufacturing nature of the mining sector has encouraged the application of automated controlling systems, more specifically GPS, to control the earthmoving fleet. Computer vision-based methods are another potential tool to provide real-time information at low-cost and to reduce human error in surface earthmoving sites as relatively clear views can be selected and the equipment offer recognizable targets. Vision-based methods have some advantages over positioning devices as they are not intrusive, provide detailed data about the behaviour of each piece of equipment, and offer reliable documentation for future reviews. This dissertation explains the development of a vision-based system, named server-customer interaction planner (SCIT), to recognize and estimate earth material loading cycles. The SCIT system consists of three main modules: object recognition, tracking, and action recognition. Different object recognition and tracking algorithms were evaluated and modified, and then the ideal methods were used to develop the object recognition and tracking modules. A novel hybrid tracking framework was developed for the SCIT system to track dump trucks in the challenging views found in the loading zones. The object recognition and tracking engines provide spatiotemporal data about the equipment which are then analyzed by the action recognition module to estimate loading cycles. The entire framework was evaluated using videos taken under varying conditions. The results highlight the promising performance of the SCIT system with the hybrid tracking engine, thereby validating the possibility of its practical application.

The rapid increase in the adoption rate of large-scale 3D printing into the construction industry has revealed a number of potential applications. This rapid implementation has also led to a higher degree of construction process optimisations and increased ability of mass customisation. Most existing applications of 3D printing technologies in construction are, however, heavily dependent on concrete and other cement-based materials, resulting in a pursuit to explore other building materials with lower environmental impact and higher adaptability to natural contexts. This pursuit has led to re-approaching earth materials and architecture to be applied in modern constructions. For centuries, earth architecture has offered potential solutions for several problems associated with buildings, such as high CO2 emissions, high embodied energy of the construction process, and depletion of natural resources. Yet this method of construction is possibly on the edge of extinction as its slow and very labourintensive process requires highly skilled craftsmen. Thanks to digital construction methods and technologies, earth materials can now become a key to promoting a new range of sustainable construction solutions that are adaptable to a local context. ‘Cob’ stands as one of many types of earth construction methods that has been utilised all over the world. Its mix consists of subsoil (earth), water, and fibrous material (typically straw), and its construction can comprise a variety of geometries and design goals without the need for formwork or any mechanical compaction method. The main aim of this research is to leverage the qualities of conventional cob construction as a groundwork for digital innovation through robotic-supported 3D printing (3DP) techniques. This aim has been approached through a comprehensive feasibility assessment of 3DP cob walls. The feasibility study included four main lines of exploration. First is the material fabrication and design process. In this line, the research systematically explored the relationship between the revised cob recipes and the geometrical and design characteristics offered by the new 3DP system. The findings of this exploration provide a new understanding about the opportunities and challenges of the current 3DP cob process, which becomes the basis to develop a novel 3DP system for earth-based materials. The second line examined the structural feasibility of using 3DP cob walls used in low-rise residential buildings. This investigation involved monotonic axial compression tests, in addition to a numerical modelling via Finite Element Analysis (FEA). The results proved the ability of 3DP cob load-bearing walls to support a two-storey residential house and meet building regulations. The test also established an optimised design chart, describing the relationship between building design and the loadbearing capacity of 3DP cob buildings. The third line of exploration involved investigating the thermal conductivity of 3DP cob walls. The assessment has revealed a lower thermal conductivity of 3D printed cob (as low as 0.32 W/mK) compared to its manually constructed cob counterparts, which means using 3DP cob for the building walls would potentially reduce heating and cooling energy use in the building. The fourth exploration focused on assessing the environmental impacts of 3DP cob walls using a Life Cycle Assessment (LCA) method, from cradle to site. The results showed a superior environmental performance of 3DP cob over the concrete-based construction methods while providing the same structural functionality in a onestory house. The results also indicate that the use of renewable energy resources can further boost the environmental potentials of 3DP cob for future construction. In summary, this research brings 3DP cob construction closer to full-scale applications. On a broader scale, the study contributes to the disciplines of architectural design and construction by providing a framework capable of bridging the knowledge gap between vernacular modes of architecture and contemporary digital practice. Moreover, this technology is not exclusive for new buildings as it can potentially be a useful strategy for conservation and repairing existing cob buildings. This is expected to benefit architects, designers and researchers currently looking into indigenous crafts as a source of material and design knowledge for a revisited digital-based architecture.
Thesis (Ph.D.) -- University of Adelaide, School of Architecture & Built Environment, 2021

The growing interest in optical quantum systems has led to the exploration of multiple platforms. Though pioneering experiments were performed in trapped atom and trapped ion systems, solid state systems show promise of being scalable and robust. Rare earth dopants in crystalline hosts are an appealing option because they possess a rich spectrum of energy levels that result from a partially filled electron orbital. While level structure varies across the period, all elements possess crystal field splittings corresponding to near infra-red or optical frequencies, as well as Zeeman and often hyperfine levels separated by radio frequency and microwave frequencies. These levels demonstrate long excited-state lifetimes and coherence times and have been used in diverse applications, including demonstrating storage of a photonic state, converting of optical to microwave photons, and manipulating a single ion as a single qubit. The ions' weak interaction with their environment results in low coupling to optical fields, which had previously required measurements with macroscopically large ensembles of ions. Coupling the ions to an optical cavity enables the use of a smaller ensemble, which is required for the development of the aforementioned technologies in an on-chip scalable architecture.

This thesis contains recent progress towards fabricating optical micro and nanocavities coupled to ensembles of erbium ions, mainly erbium in yttrium orthosilicate. In one design, focused ion beam milling was used to create a triangular nanobeam photonic crystal cavity in a bulk erbium-doped substrate. A second design leveraged the fabrication capabilities of silicon photonics, defining amorphous silicon ring resonators using electron beam lithography and dry etching. These devices coupled evanescently to erbium ions below the ring, in the bulk substrate. Simulation, design, fabrication, and characterization of both resonators are discussed. Coupling between the ions and the resonator is demonstrated for each, and capabilities offered by these devices are described. Preliminary work implementing coherent control of erbium ions is presented. Lastly, alternative substrates are evaluated for possible future solid-state erbium systems.

碩士
長榮大學
資訊管理研究所
97
Along with the advantages in information technology (IT), teachers try to integrate teaching methods by using IT for many years. However, the advantage of IT is very fast and its application on education needs training and time, it is very important to help teachers to use IT on curriculum design and teaching. This research adapt technology acceptance model (TAM) to study the advantage of IT on teaching. According to the past research, there are many difficulties to teach the geophysical related subjects, such as latitude, longitude, weather, cloud, precipitation…etc. Also students will make some misconception from traditional curriculum. These difficulties could be resolved by using geographic information system (GIS). Google Earth is a new but popular GIS on web world; users can fly to every corner of the planet during mouse clicks. For these reasons, we developed auto-formed teaching materials on Google Earth; teacher can use it on weather related curriculum. Questionnaire survey was made to estimate the advantage of GIS on teaching. Preliminary results indicate that teachers are satisfied on this design, also it shown high acceptance and willingness on using GIS in geophysical related subjects.

There has been a rising interest by the building sector in using passive solutions to regulate the indoor relative humidity, since humidity levels can directly affect the health and comfort of the occupants. Earth based materials are known for their ability to regulate the relative humidity and improve indoor comfort. Another motivation is the potential to reduce the energy consumption of air conditioning systems. The assessment of the hygrothermal transfers within earthen walls/plasters has been the focus of many researchers, but the proper modelling and coupling of these characteristics for unconventional materials like earthen walls and plasters still is a major scientific and technical challenge. The main objective of this dissertation consists in first to check the validity of steady state material characteristics obtained through standard procedures. Furthermore, validate different assumptions and the reliability of the different methods to determine the precision of the experimental test results. The second objective is to analyse the influence of temperature on those characteristics and their consequences on the hygrothermal behaviour. For that purpose, two types of porous hygroscopic materials are studied: compressed earth samples and earth plasters with the addition of organic natural fibres. Results showed a high variability due to experimental set ups and conditions. However the influence of temperature on the sorption and transfer properties could be determined. An analysis of the results based on thermodynamics gave surface characteristics and the heat involved in the adsorption and condensation process of the materials used.

Bioconsolidation is a relatively novel technique used for consolidation, repair, protection and improvement of construction materials. This biotechnology is based on the precipitation of chemical compounds produced by microbial metabolism. It can be used for treatment or formulation. Although recently applied in several construction materials, such as earth blocks or cement-based materials, bioconsolidation has been unexplored on earth-based plastering mortars. Although the use of earth mortars for earth plasters has been growing on recent years for its eco-efficiency, they are less resistant to damage by contact with water. Therefore, the use of a bioproduct may have a great potential for the improvement of earth mortars´ weaknesses. In the present thesis, two types of bioconsolidation techniques have been studied on earth mortars: as a biotreatment for the improvement of surface properties; and as a component for earth mortars’ formulation (bioformulation) for the improvement of the whole material. The bioproducts used are based on microbial iron mineralization using Escherichia coli cells, since iron compounds are present in earth materials, are non-toxic, easy to handle and are not expensive. Several experimental conditions have been studied leading to the proposal that iron concentration is a key parameter. Tested biotreatments show promising results, producing a slight consolidative effect and significant increasing of water absorption resistance of earth mortars. Bioformulated mortars present a very distinct macrostructure, with a great decrease on mechanical properties. Nevertheless, they achieve a considerable improvement on resistance towards water and a lower thermal conductivity. The results show the interest on further studies on the use of iron-based bioproducts on earth mortars.

Les connaissances sur la morphologie de la Terre sont essentielles à la compréhension d’une variété de processus géomorphologiques et hydrologiques. Des avancées récentes dans le domaine de la télédétection ont significativement fait progresser notre habilité à se représenter la surface de la Terre. Parmi celles-ci, les données d’élévation LiDAR permettent la production de modèles numériques d’altitude (MNA) à haute résolution sur de grands territoires. Le LiDAR est une avancée technologique majeure permettant aux scientifiques de visualiser en détail la morphologie de la Terre et de représenter des reliefs peu prononcés, et ce, même sous la canopée des arbres. Une telle avancée technologique appelle au développement de nouvelles approches innovantes afin d’en réaliser le potentiel scientifique. Dans ce contexte, le présent travail vise à développer deux approches de cartographie numérique utilisant des données d’élévation LiDAR et servant à l’évaluation de la composition du sous-sol. La première approche à être développée utilise la localisation de crêtes de plage identifiées sur des MNA LiDAR afin de modéliser l’étendue maximale de la mer de Champlain, une large paléo-mer régionalement importante. Cette approche nous a permis de cartographier avec précision les 65 000 km2 autrefois inondés par la mer. Ce modèle sert à l’évaluation de la distribution des sédiments marins et littoraux dans les basses-terres du Saint-Laurent. La seconde approche utilise la relation entre des échantillons de matériel parental des sols (MPS) et des attributs topographiques dérivés de données LiDAR afin de cartographier à haute résolution et à une échelle régionale le MPS sur le Bouclier canadien. Pour ce faire, nous utilisons une approche novatrice combinant l’analyse d’image orientée-objet (AIOO) avec une classification par arbre décisionnel. Cette approche nous a permis de produire une carte du MPS à haute résolution sur plus de 185 km2 dans un environnement hétérogène de post-glaciation. Les connaissances issues de la production de ces deux modèles ont permis de conceptualiser la composition du sous-sol dans les régions limitrophes entre les basses-terres du Saint-Laurent et le Bouclier canadien. Ce modèle fournit aux chercheurs et aux gestionnaires de ressources des connaissances détaillées sur la géomorphologie de cette région et contribue à l’amélioration de notre capacité à saisir les services écosystémiques et à prédire les aléas environnementaux liés aux processus du sous-sol.
Knowledge of the earth’s morphology is essential to the understanding of many geomorphic and hydrologic processes. Recent advancements in the field of remote sensing have significantly improved our ability to assess the earth’s surface. From these, LiDAR elevation data permits the production of high-resolution digital elevation models (DEMs) over large areas. LiDAR is a major technological advance as it allows geoscientists to visualize the earth’s morphology in high detail, even allowing us to resolve low-relief landforms in forested areas where the surface is obstructed by vegetation cover. Such a technological advance calls for the development of new and novel approaches to realize the scientific potential of this new spatial data. In this context, the present work aims to develop two digital mapping approaches that use LiDAR elevation data for assessing the earth’s subsurface composition. The first approach to be developed uses the location of low-relief beach ridges observed on LiDAR-derived DEMs to map the extent of a large and regionally important paleo-sea, the Champlain Sea. This approach allowed us to accurately map the 65,000 km2 area once inundated by sea water. The model serves to the assessment of the distribution of marine and littoral sediments in the St. Lawrence Lowlands. The second approach uses the relationship between field-acquired samples of soil parent material (SPM) and LiDAR-derived topographic attributes to map SPM at high-resolution and at a regional scale on the Canadian Shield. To do so, we used a novel approach that combined object-based image analysis (OBIA) with a classification tree algorithm. This approach allowed us to produce a fine-resolution 185 km2 map of SPM in a heterogeneous post-glaciation Precambrian Shield setting. The knowledge obtained from producing these two models allowed us to conceptualize the subsurface composition at the limit between the St. Lawrence Lowlands and the Canadian Shield. This insight provides researchers and resource managers with a more detailed understanding of the geomorphology of this area and contributes to improve our capacity to grasp ecosystem services and predict environmental hazards related to subsurface processes.