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Hormigones eco-celulares one-part (ecc-op) basados 100 % en materiales residualesFont Pérez, Alba 12 March 2021 (has links)
Tesis por compendio / [ES] El presente trabajo de investigación presenta un nuevo concepto de hormigón celular basado en el consumo minimizado de recursos y casi nulo de energías, durante la fase de producción del material como a lo largo de la vida útil de las edificaciones: los nuevos hormigones eco-celulares "one-part" (ECC-OP). Se lleva a cavo el desarrollo, caracterización y evaluación medioambiental del material.
En la primera etapa de trabajo, se introducen e investigan los nuevos hormigones celulares geopoliméricos (GCC) y hormigones celulares de activación alcalina (AACC) en los que el cemento Portland, conocido por su uso indiscriminado a nivel mundial y su gran impacto ambiental y económico, se sustituye por el catalizador gastado de craqueo catalítico (FCC) y la escoria de alto horno (BFS) respectivamente. A partir de la concepción de estos nuevos materiales se va introduciendo variables de mejora: i) empleo de agentes aireantes alternativos: papel de aluminio reciclado, agua oxigenada y sub-productos del tratamiento de escorias salinas; ii) desarrollo del concepto de co-molienda entre los precursores y los aireantes alternativos; iii) combinación de aireación mecánica y química de las matrices mediante polvo de aluminio y un espumante, el lauril sulfato de sodio; y vi) estudio del comportamiento frente a tratamientos de curado alternativos al autoclave. Los materiales se estudian y comparan microestructuralmente, se ensayan sus características funcionales (densidad, resistencia mecánica a la compresión y conductividad térmica) y se evalúan medioambientalmente. Además, se caracteriza la matriz porosa resultante combinando técnicas microscópicas y de análisis de imagen, así como mediante ensayos hídricos.
En esta segunda etapa de trabajo, se introduce el concepto de hormigón eco-celular (ECC), en el que los silicatos comerciales de la disolución activadora se sustituyen por una fuente alternativa de sílice procedente de un residuo agrícola: la ceniza de cáscara de arroz (RHA). Se desarrollan e investigan sistemas de ECCs con FCC y ECCs con BFS, en los que se emplea como agente aireante el papel de aluminio residual y se incorpora mediante el procedimiento de co-molienda con el precursor. Los ECCs se diseñan para obtener unas propiedades óptimas y se comparan con los TCC, GCC y AACC, tanto física y mecánicamente como medioambientalmente. Como resultado, se obtienen ECCs estables, con densidades inferiores a los 1000kg/cm3 y con los que se consigue una reducción de las emisiones de CO2 del 74 % en el caso de los constituidos con FCC y del 78 % para los constituidos con BFS, respecto a los sistemas tradicionales.
Finalmente, en la tercera etapa de trabajo se presenta la mayor innovación en cuanto a la ecoeficiencia y el objetivo de consumo nulo de recursos naturales planteados: el estudio de la ceniza de hueso de oliva (OBA) como fuente alcalina alternativa en la disolución activadora. La OBA es un residuo agrícola compuesto fundamentalmente de potasio y calcio, y se presenta como una alternativa potencial para la sustitución del hidróxido alcalino comúnmente empleado en la activación de la BFS. El empleo de la OBA se estudia inicialmente en sistemas de activación alcalina de BFS: se desarrollan, en primer lugar, sistemas binarios (BAAM) con OBA/BFS y a continuación se complementa el estudio combinando esta ceniza con la RHA constituyendo sistemas ternarios (TAAM) con OBA/BFS/RHA.
Una vez sentadas las bases previas, se desarrolla la cuarta etapa experimental, se aplica por primera vez la modalidad de fabricación "one-part", que consiste en la co-molienda de todos los materiales sólidos de modo que únicamente se requiere de su mezcla con agua para la producción del material final: los nuevos ECC-OP. Estos materiales son diseñados y analizados en torno a las características funcionales exigidas por la normativa europea para la industria de los prefabricados y se evalúan medioambientalmente media / [CA] El present treball d'investigació presenta un nou concepte de formigó cel·lular basat en un consum mínim de recursos i quasi nul d'energies durant la fase de producció del material així com durant la vida útil de les edificacions: els nous formigons eco-cel·lulars "one-part" (ECC-OP). Es desenvolupa, caracteritza i avalua mediambientalment el material mitjançant un pla de treball que s'ha distribuït en passos graduals de millora. Les etapes del treball han estat centrades d'una banda en els materials constituents i d'altra banda en el procediment de fabricació.
A la primera etapa de treball, s'introduïxen i investiguen els nous formigons cel·lulars geopolimèrics (GCC) i formigons cel·lulars d'activació alcalina (AACC) en els quals el ciment Pòrtland, conegut pel seu us indiscriminat i el seu gran impacte ambiental i econòmic, se substituïx per catalitzador gastat de craqueig catalític (FCC) i escòria d'alt forn (BFS) respectivament. A partir de la concepció d'estos nous materials es van introduint variables de millora: i) ús d'agents aireantes alternatius: paper d'alumini reciclat, aigua oxigenada i subproductes del tractament d'escòries salines; ii) desenvolupament del concepte de co-mòlta entre els precursors i els reactius generadors de gas alternatius; iii) combinació de generació de porositats a les matrius per medi mecànic i químic utilitzant pols d'alumini i un tensioactiu, el lauril sulfat de sodi; i iv) estudi del comportament amb l'aplicació de tractaments de curat alternatius a l'autoclau. Els materials s'estudien i comparen micro-estructuralment, s'analitzen les propietats funcionals (densitat, resistència mecànica a la compressió i conductivitat tèrmica) i s'avaluen mediambientalment. A més, es caracteritza la matriu porosa resultant combinant tècniques microscòpiques i d'anàlisi d'imatge, així com per mitjà d'assajos hídrics.
En esta segona etapa de treball, s'introduïx el concepte de formigó eco-cel·lular (ECC) , en el que els silicats comercials de la dissolució activadora se substituïxen per una font alternativa de sílice procedent d'un residu agrícola: la cendra de corfa d'arròs (RHA) . S' investiguen sistemes d'ECC amb FCC i sistemes d'ECC amb BFS, en els que s'empra com a agent generador de gas el paper d'alumini residual i s'incorpora per mitjà del procediment de co-mòlta amb el precursor. Els ECCs es dissenyen per a obtindre unes propietats òptimes i es comparen amb els TCC, GCC i AACC, tant física i mecànicament com mediambientalment. Com a resultat, s'obtenen ECCs estables, amb densitats inferiors als 1000kg/cm3 i amb els que s'aconseguix una reducció de les emissions de CO2 del 74 % en el cas dels constituïts amb FCC i del 78 % per als constituïts amb BFS, respecte als sistemes tradicionals.
En la tercera etapa de treball es presenta la major innovació quant a l'eco-eficiència i l'objectiu de consum nul de recursos naturals: l'estudi de la cendra d'os d'oliva (OBA) com a font alcalina alternativa per a la fabricació de la dissolució activadora. L'OBA és un residu agrícola compost fonamentalment de potassi i calci, i es presenta com una alternativa potencial per a la substitució de l'hidròxid alcalí comunament empleat en l'activació de la BFS. L'ús de l'OBA s'estudia inicialment en sistemes d'activació alcalina de BFS: sistemes binaris (BAAM) amb OBA/BFS. A continuació, es complementa l'estudi que combina l'ús de l'OBA amb la RHA constituint sistemes ternaris (TAAM) formats per OBA/BFS/RHA.
Finalment, s'aplica per primera vegada la modalitat de fabricació "one-part", que consistix en la co-mòlta de tots els materials sòlids de manera que únicament es requerix de la seua mescla amb aigua per a la producció del material final: els nous ECC-OP. Estos materials són dissenyats i analitzats segons les característiques funcionals exigides per la normativa europea per a la indústria dels prefabricats i s'avaluen mediambientalment pe / [EN] In this investigation, a new concept of cellular concrete had been developed based on both the low natural resources as well as nearly zero-energy consumptions: the new one-part eco-cellular concrete (ECC-OP). The development, the characterization and the environmental assessment of the material were carried out. A working plan has been broken down into progressive stages where the improvements were focused on the constitutive materials as well as on the manufacture procedures.
In the first working step, the geopolymer cellular concretes (GCC) and the alkali-activated cellular concretes (AACC) were investigated. The OPC worldwide known by its high economic costs, non-reasonable use and its environmental issues was replaced for the fluid catalytic cracking catalyst residue (FCC) and for the blast furnace slag (BFS) respectively. In the new GCC and AACC systems, steps of improvements were introduced progressively: i) the use of alternative aerating agents as the recycled aluminium foil, hydrogen peroxide and salt-slags recycled by-products; ii) a new concept of co-milling between precursors and the alternative aerating agents was introduced; iii) matrix aeration by the chemical and mechanical means where the aluminium powder was combined with the sodium lauryl sulphate (SLS), and vi) alternative curing treatments to the traditional autoclave. A microstructural and functional characterisation and an environmental assessment of the materials were carried out. Furthermore, the air-void characterization was done by microscopic, image analysis and hydric tests means.
In the second working step, the new eco-cellular concretes (ECC) were introduced and investigated. The silicates in the alkali-activated dissolution were replaced by an alternative silica sourced from an agricultural residue: the rice husk ash (RHA). The new systems were developed with the use of both the BFS and the FCC as precursors and the aerating agent was the recycled aluminium foils by the co-milling procedure. The optimal properties of the new ECC were investigated and a comparison with the TCC, GCC and AACC was done. The new ECCs yielded densities less than 1000kg/cm3 and, comparing with the TCC systems, the CO2 emissions were lower in 74 % when the FCC was employed and in 78 % when the BFS was employed.
Finally, in the third working step, the more highlighted novelty in the ecoefficiency and the objective of near cero natural resources consumption was presented: the study of the olive-stone biomass ash (OBA) as an alternative alkali source for the activating dissolution. The OBA is a farming waste mainly composed of potassium and calcium, thus, is a well alternative to the traditional potassium hydroxide employed for the BFS activation. The OBA was firstly introduced in binary systems (BAAM) composed by OBA/BFS mixed with water. Then, the OBA and RHA were combined to the BFS activation in the new ternary systems composed 100 % by residues (TAAM). A complete characterization of the OBA, as well as the mortars and pastes manufacture procedure investigations were carried out. The microstructural, physical and mechanical characterization of the new TAAM was done to its application in the cellular concrete technology.
The last working step of the present investigation consisted of the ECCs based on BFS activated with RHA and OBA. Furthermore, for the first time, the "one-part" manufacture procedure was applied to obtain the new "one-part" eco-cellular concretes (ECC-OP). The "one-part" consist of the co-milling of all solid materials and their mix with water to obtain the cellular concrete (similar to the traditional OPC procedure). The materials were designed from scratch: dosages, characterization, comparisons with the TCC, AACC and ECC, European standards compliments. Furthermore, environmental issues of the ECC-OP through the cradle-to-gate modality of the life circle analysis (LCA) were evaluated obtaining their 100 years Global Warming Potential (GWP-100). / Font Pérez, A. (2020). Hormigones eco-celulares one-part (ecc-op) basados 100 % en materiales residuales [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/141092 / Compendio
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Desarrollo y caracterización de materiales sostenibles con subproductos de la industria del lino para aplicaciones de envasado bajo el marco de la Economía CircularAgüero Rodríguez, Ángel 02 September 2020 (has links)
Tesis por compendio / [EN] Framed within the approach of a circular economy, this doctoral thesis studies the possibilities on the use of agricultural by-products for the manufacture of materials that could potentially replace polymers of petrochemical origin in the food packaging sector.
In this thesis different by-products from the flax industry have been studied to develop and subsequently characterize composite materials with high environmental performance. For this, a biodegradable polymer has been used in addition to flax by-products as a matrix for said composite materials. The polymer used is polylactic acid (PLA).
The flax by-products that have been used have been both in the form of filler / particulate materials and additives. Thus, short flax fiber and flax seed meal particles have been used as reinforcement materials in green composites with a PLA matrix: On the other hand, two types of chemically modified flax oil (epoxidized flax oil-ELO , and maleinized flax oil-MLO) have been used as plasticizers and / or compatibilizing agents in both parts of the work. In order to carry out a comparative analysis, other compatibilizing techniques were used to improve the interaction between the matrix and the reinforcing materials. To this end, in the different phases of this work, treatments with particle silanes, alkalinization, reactive extrusion with an epoxide-ESAO oligomer and with a styrene-methacrylate-PS-co-GMA copolymer have been used.
Furthermore, the initial phase of this thesis consists of verifying the positive effect that MLO has when it is used as additives in PLA matrix composites. After checking this effect, a second stage consisted of optimizing the percentage in which it can be included in the formulation. The composite material developed for this previous study consists of a PLA matrix with a fixed content of Diatomaceous Earth.
On the other hand, due to the nature of the thesis, focused on sustainability and the study of innovative ways of revaluing resources of natural origin, a study of the recyclability of the materials developed was also carried out. To do this, the deterioration of the PLA matrix undergoing several re-processing cycles was studied, simulating the standard polymer recycling processes. / [ES] Enmarcándose dentro del planteamiento de una economía circular, la presente tesis doctoral estudia las posibilidades sobre el aprovechamiento de subproductos agrícolas para la fabricación de materiales que potencialmente pudieran sustituir a los polímeros de origen petroleoquímico en el sector del envasado de alimentos.
En esta tesis se han estudiado distintos subproductos procedentes de la industria del lino para desarrollar y posteriormente caracterizar materiales compuestos con un alto rendimiento medioambiental. Para ello se ha empleado además de los subproductos del lino, un polímero biodegradable como matriz de dichos materiales compuestos. El polímero empleado es el ácido poliláctico (PLA).
Los subproductos del lino que se han empleado han sido tanto en forma de materiales de relleno/partículas, como de aditivos. De este modo, se ha empleado fibra corta de lino y partículas de harina de semilla de lino como materiales de refuerzo en green composites con matriz de PLA: Por otro lado, dos tipos de aceite de lino modificado químicamente (aceite epoxidado de lino-ELO, y aceite maleinizado de lino-MLO) se han empleado como plastificantes y/o agentes compatibilizantes en ambas partes del trabajo. Para poder llevar a cabo un análisis comparativo, otras técnicas de compatibilizan se emplearon para mejorar la interacción entre la matriz y los materiales de refuerzo. Con este fin, en las distintas fases de este trabajo se han empleado tratamientos con silanos de las partículas, alcalinización, extrusión reactiva con un oligómero epóxido-ESAO y con un copolimero estireno-metacrilato-PS-co-GMA.
Además, la fase inicial de dicha tesis consiste en la comprobación del efecto positivo que ejerce el MLO cuando se emplea como aditivos en materiales compuestos de matriz de PLA. Tras la comprobación de dicho efecto, una segunda etapa consistió en la optimización del porcentaje en que este se puede incluir en la formulación. El material compuesto desarrollado para este estudio previo consiste en una matriz de PLA con un contenido fijo de Tierra de Diatomeas.
Por otro lado, debido a la naturaleza de la tesis, enfocada hacia las sostenibilidad y estudio de vías novedosas de re valorización de recursos de origen natural, se llevó también a cabo un estudio de la reciclabilidad de los materiales desarrollados. Para ello se estudió el deterioro que supone en la matriz de PLA el sometimiento a varios ciclos de re procesado, simulando los procesos estándares de reciclado de polímeros. / [CA] Emmarcant-se dins del plantejament d'una economia circular, la present tesi doctoral estudia les possibilitats sobre l'aprofitament de subproductes agrícoles per a la fabricació de materials que potencialment pogueren substituir als polímers d'origen *petroleoquímico en el sector de l'envasament d'aliments. En aquesta tesi s'han estudiat diferents subproductes procedents de la indústria del lli per a desenvolupar i posteriorment caracteritzar materials compostos amb un alt rendiment mediambiental. Per a això s'ha emprat a més dels subproductes del lli, un polímer biodegradable com a matriu d'aquests materials compostos. El polímer empleat és l'àcid *poliláctico (PLA). Els subproductes del lli que s'han emprat han sigut tant en forma de materials de farcit/partícules, com d'additius. D'aquesta manera, s'ha emprat fibra curta de lli i partícules de farina de llavor de lli com a materials de reforç en *green *composites amb matriu de PLA: D'altra banda, dos tipus d'oli de lli modificat químicament (oli *epoxidado de lli-*ELO, i oli *maleinizado de lli-*MLO) s'han emprat com a plastificants i/o agents *compatibilizantes en totes dues parts del treball. Per a poder dur a terme una anàlisi comparativa, altres tècniques de compatibilitzen es van emprar per a millorar la interacció entre la matriu i els materials de reforç. A aquest efecte, en les diferents fases d'aquest treball s'han emprat tractaments amb *silanos de les partícules, *alcalinización, extrusió reactiva amb un *oligómero *epóxido-*ESAO i amb un *copolimero estiré-metacrilat-PS-*co-*GMA. A més, la fase inicial d'aquesta tesi consisteix en la comprovació de l'efecte positiu que exerceix el *MLO quan s'empra com a additius en materials compostos de matriu de PLA. Després de la comprovació d'aquest efecte, una segona etapa va consistir en l'optimització del percentatge en què aquest es pot incloure en la formulació. El material compost desenvolupat per a aquest estudi previ consisteix en una matriu de PLA amb un contingut fix de Terra de Diatomees. D'altra banda, a causa de la naturalesa de la tesi, enfocada cap a les sostenibilitat i estudi de vies noves de re valorització de recursos d'origen natural, es va portar també a cap un estudi de la *reciclabilidad dels materials desenvolupats. Per a això es va estudiar la deterioració que suposa en la matriu de PLA el sotmetiment a diversos cicles de re processat, simulant els processos estàndard de reciclatge de polímers. / This research was funded by the Ministry of Science, Innovation, and
Universities (MICIU) project number MAT2017-84909-C2-2-R. L. Quiles-Carrillo is
recipient of a FPU grant (FPU15/03812) from the Spanish Ministry of Education,
Culture, and Sports (MECD). D. Lascano acknowledges UPV for the grant received
though the PAID-01-18 program. / Agüero Rodríguez, Á. (2020). Desarrollo y caracterización de materiales sostenibles con subproductos de la industria del lino para aplicaciones de envasado bajo el marco de la Economía Circular [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149383 / Compendio
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Modelo ProLab: Transforma, aprovechamiento de residuos orgánicos destinados a la alimentación porcinaTorbisco Chumpitaz, María Isabel, Lopez Altamirano, Sheila Guillermina, Del Carpio Portocarrero, Alan Giusseppe, Alzamora Arévalo, Renato Augusto 04 July 2024 (has links)
Es indiscutible que siempre existirán los desechos orgánicos producto del consumo
humano y que el deficiente tratamiento de estos es uno de los factores más contaminantes de
nuestro medio ambiente, debido a la emisión de gases de efecto invernadero. Lima está entre las
diez ciudades latinoamericanas más contaminadas según el World Air Quality, y los distritos de
Lima Centro no escapan a esta problemática. El presente trabajo brinda una solución de negocio
que mitiga los efectos contaminantes de la descomposición de los desperdicios orgánicos debido
al procesamiento de estos a través de un tratamiento integral desde la segregación en la fuente
hasta convertirlos en parte de un alimento balanceado para ganado porcino. Esta propuesta
permite convertir residuos de unos en insumos productivos para otros, generando una alternativa
de economía circular catalogada como innovación incremental.
La deseabilidad y factibilidad del proyecto se sustentan satisfactoriamente en los
capítulos correspondientes con las evidencias del caso, lo cual aminora el grado de incertidumbre
en un nuevo proyecto respecto a la acogida del producto y su cadena de valor, además en el
plano financiero se consigue un VAN de S/ 3’972,928 y una TIR de 110% en un horizonte de
cinco años lo cual lo hace viable en términos financieros también. Este proyecto promueve tres
Objetivos de Desarrollo Sostenible (ODS), específicamente la ODS 3, 12 y 13, lo cual pretende
guiar el accionar de la empresa en la búsqueda del impacto positivo en la salud y bienestar de la
sociedad, logrando cifras relevantes como al quinto año de operación lograr recuperar 950
toneladas anuales de residuos orgánicos que evitarían emitir hasta 3,750 toneladas de CO2. / It is indisputable that organic waste resulting from human consumption will always exist
and that its poor treatment is one of the most polluting factors in our environment, due to the
emission of greenhouse gases. Lima is among the ten most polluted Latin American cities
according to World Air Quality and the districts of Central Lima do not escape this problem.
This thesis provides a business solution that mitigates the polluting effects of the decomposition
of organic waste due to its processing through a comprehensive treatment from segregation at the
source to converting it into part of a balanced feed for pigs. This proposal makes it possible to
convert waste from some into productive inputs for others, generating a circular economy
alternative classified as incremental innovation.
The desirability and feasibility of the project are satisfactorily supported in the
corresponding chapters with the evidence of the case, which reduces the degree of uncertainty in
a new project regarding the acceptance of the product and its value chain, in addition, on the
financial level, a NPV of S/ 3’972,928 and an IRR of 110% over a five-year horizon, which also
makes it viable in financial terms. This project promotes three Sustainable Development Goals
(SDGs), specifically SDG 3, 12 and 13, which aims to guide the company's actions in the search
for a positive impact on the health and welfare of society, achieving relevant figures such as fifth
year of operation to recover 950 tons of organic waste per year that would avoid emitting up to
3,750 tons of CO2.
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Aerodynamic Performance of Cables with Spiral Protuberances in Strong Winds / 強風下におけるスパイラル突起付きケーブルの空力特性Dao, Minh Thu 25 March 2024 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第25236号 / 工博第5195号 / 新制||工||1992(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 八木 知己, 教授 KIM Chul-Woo, 教授 高橋 良和 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
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Life cycle sustainability assessment of alternative green roofs – A systematic literature reviewBalasbaneh, A.T., Sher, W., Madun, A., Ashour, Ashraf 21 November 2023 (has links)
Yes / There is general agreement on the importance of green roofs as ways of reducing GHG emissions, reducing overall costs and improving sustainability in urban areas. This systematic literature review highlights life cycle sustainability assessment as an essential criterion to evaluate green roofs. A bibliometric analysis was used to quantitatively review relevant literature. The Scopus database was chosen as a bibliographic database of academic publications. Thes period of search started from 2003 and final search was conducted on February 15, 2023. Based on further in-depth reading, 88 publication records which met the selection criteria, including 74 papers and 14 conference papers. Researchers from the United States contributed almost 31 % of the documents. We evaluated leading studies in this field and discussed assessment method, system boundaries and research gaps through a critical literature review and a systematic search review. Finally, we propose a framework and identify a gap and future research. The environmental aspect of green roofs have received more attention than economic issues. We found that most economic evaluations of green roofs are limited to their construction stage. As yet there is no comprehensive social study on green roofs. We considered a unified study of the economic, environmental impact and social evaluation of green roofs to be warranted. Additionally, various measurement methods should be used to assess the economic profitability of green roofs over the long term. In summary, this study provides a deeper understanding of the environmental, social, and economic performance of green roofs and identifies research gaps as well as future research directions.
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Dynamics of Long-Term Orbit Maintenance Strategies in the Circular Restricted Three Body ProblemDale Andrew Pri Williams (18403380) 19 April 2024 (has links)
<p dir="ltr">This research considers orbit maintenance strategies for multi-body orbits in the context of the Earth-Moon Circular Restricted Three Body Problem (CR3BP). Dynamical requirements for successful long-term orbit maintenance strategies are highlighted.</p>
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Free Vibration of Bi-directional Functionally Graded Material Circular Beams using Shear Deformation Theory employing Logarithmic Function of RadiusFariborz, Jamshid 21 September 2018 (has links)
Curved beams such as arches find ubiquitous applications in civil, mechanical and aerospace engineering, e.g., stiffened floors, fuselage, railway compartments, and wind turbine blades. The analysis of free vibrations of curved structures plays a critical role in their design to avoid transient loads with dominant frequencies close to their natural frequencies.
One way to increase their areas of applications and possibly make them lighter without sacrificing strength is to make them of Functionally Graded Materials (FGMs) that are composites with continuously varying material properties in one or more directions.
In this thesis, we study free vibrations of FGM circular beams by using a logarithmic shear deformation theory that incorporates through-the-thickness logarithmic variation of the circumferential displacement, and does not require a shear correction factor. The radial displacement of a point is assumed to depend only upon its angular position. Thus the beam theory can be regarded as a generalization of the Timoshenko beam theory. Equations governing transient deformations of the beam are derived by using Hamilton's principle. Assuming a time harmonic variation of the displacements, and by utilizing the generalized differential quadrature method (GDQM) the free vibration problem is reduced to solving an algebraic eigenvalue problem whose solution provides frequencies and the corresponding mode shapes. Results are presented for different spatial variations of the material properties, boundary conditions, and the aspect ratio. It is found that the radial and the circumferential gradation of material properties maintains their natural frequency within that of the homogeneous beam comprised of a constituent of the FGM beam. Furthermore, keeping every other variable fixed, the change in the beam opening angle results in very close frequencies of the first two modes of vibration, a phenomenon usually called mode transition. / Master of Science / Curved and straight beams of various cross-sections are one of the simplest and most fundamental structural elements that have been extensively studied because of their ubiquitous applications in civil, mechanical, biomedical and aerospace engineering. Many attempts have been made to enhance their material properties and designs for applications in harsh environments and reduce weight. One way of accomplishing this is to combine layerwise two or more distinct materials and take advantage of their directional properties. It results in a lightweight structure having overall specific strength superior to that of its constituents. Another possibility is to have volume fractions of two or more constituents gradually vary throughout the structure for enhancing its performance under anticipated applications. Functionally graded materials (FGMs) are a class of composites whose properties gradually vary along one or more space directions. In this thesis, we have numerically studied free vibrations of FGM circular beams to enhance their application domain and possibly use them for energy harvesting.
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On the Effect of Circular Economy strategies on theconsumer-EV brand relationshipLarsson, Filip, Garcia Jaime, Gabriel January 2023 (has links)
The transport sector, particularly electric vehicles (EVs), plays a pivotal role in mitigating climate change. However, the use of lithium-ion (li-ion) batteries in EVs raises sustainability concerns due to their limited lifespan, high costs, potential raw material shortages, and the environmental impact of raw material mining. These concerns necessitate the incorporation of sustainable development strategies into EV innovation plans. With a booming EV market, both luxury and non-luxury brands are being urged to adopt circular economy strategies, such as battery reuse and recycling, to enhance the brand-customer relationship. While the automotive industry has begun implementing these strategies, there is limited research on how they affect customer acceptance and the impact on luxury versus non-luxury brands. This thesis examines the existence of differences and influence of these circular economy strategies on the EV industry, with a particular focus on li-ion batteries, and analyzes their impact on luxury and non-luxury automotive EV brands.
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Circular Business Model for Sri Lankan Tourism SMEs : A qualitative study on how tourism SMEs can adopt circular business modelNawarathna, Alahakoon Kankanamalage Buddhika Prasadini, Perera, Balasuriyage Nirasha Sewwandi January 2024 (has links)
Tourism is an industry that makes important contributions to the Sri Lanakan economy. Thelong-term survival of this industry depends on the longevity of natural resources and thebeauty of the environment. Today, the tourism industry is impacting the naturalenvironment negatively. The concept of circular economy is gaining global attention assustainable alternative to traditional economic practice. Through qualitative approach, thisthesis investigates how the Sri Lanka tourism industry can adopt a circular business modelto mitigate its negative impacts. The methodology utilized semi-structured interviews withfive business personalities involved in hotel and accommodation sectors listed undercategory of small and medium-sized business. The study first examined the awareness and perceptions of the circular business modelconcept among tourism SMEs in Sri Lanka. This is a step was extremely important, asawareness is a fundamental prerequisite for adopting more sustainable practices. Theresearch investigated the current level of understanding and knowledge about circularbusiness model concepts within these small and medium-sized enterprises. This exploredhow tourism businesses in Sri Lanka currently view the circular model whether they see itas a practical, beneficial approach or faced concerns and lack knowledge. Next, under Opportunities and Challenges the study explored the key opportunities andchallenges that either enable or challenge the transition towards circular business models.On the opportunity side, the research examined factors that could facilitate and incentivesSMEs to achieve circularity, such as cost savings, improved brand reputation, attractingenvironmentally conscious tourists, and preserving local value chains and resources. Thefindings also highlighted that some SMEs are already employing innovative circularpractices, indicating a readiness to embrace more sustainable operations. Conversely, theresearch could identify several barriers to the widespread adoption of circular practicesamong SMEs. These barriers include limited awareness of circular economy principles,financial constraints, and regulatory challenges. Finally, the study evaluated on developing practices the effectiveness of any existingbusiness development goals or initiatives related to circular economy strategies within SriLankan tourism SMEs. This involved assessing the current state of circular practices,identifying areas for improvement, and determining the specific types of support andresources needed to help these enterprises successfully adopt and sustain a circular businessmodel. The thesis suggests several avenues for future research, including road map to achieve fullysustainable circular business model. It also recommends evaluating the effectiveness ofgovernment policies and initiatives in promoting the adoption of circular economyprinciples within the tourism sector and investigating the role of technology and innovationin facilitating the transition to circular business model. Key words – Circular Business Model, Tourism SMEs Sri Lanaka, Sustainability,Resources optimization
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Navigating Compliance: Sustainable Packaging Challenges for SMEs in the EU : A study of the sustainable packaging compliance challenges that SMEs face when operating within the EUKutkaitis, Mantas, Hlasha Al Sibai, Alaa January 2024 (has links)
This thesis explores the challenges Small and Medium-sized Enterprises (SMEs) face in complying with EU sustainable packaging regulations as they pose ever tightening guidelines to follow. The study respondents are representatives from SMEs operating within the EU, who provided insights through semi-structured interviews. Employing the 7Rs framework—Rethink, Refuse, Reduce, Reuse, Repurpose, Recycle, and Rot—this research investigates how these enterprises adapt their packaging strategies to align with EU directives aimed at achieving 70% recyclable and reusable packaging by 2030. Despite varied challenges such as high costs and diverse regulatory demands across EU states, SMEs demonstrate resilience and innovation in their compliance strategies. environmental impact while maintaining economic viability. Such as an SME transitioning from using plastic packaging to cardboard, driven by both regulatory requirements and carrier fees for non-compliance, which resulted in reduced environmental impact and improved customer satisfaction. This research provides insights into the dynamic interplay between regulatory frameworks and business practices, offering a deeper understanding of sustainability in the packaging industry.
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