Tese de mestrado integrado. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 2010

Based on continuum damage mechanics (CDM), an isotropic and anisotropic damage model coupled with a novel plasticity model for plain concrete is proposed in this research. Two different damage evolution laws for both tension and compression are formulated for a more accurate prediction of the plain concrete behavior. In order to derive the constitutive equations, the strain equivalence hypothesis is adopted. The proposed constitutive model has been shown to satisfy the thermodynamics requirements, and detailed numerical algorithms are developed for the Finite Element implementation of the proposed model. Moreover, the numerical algorithm is coded using the user subroutine UMAT and then implemented in the commercial finite element analysis program Abaqus, and the overall performance of the proposed model is verified by comparing the model predictions to various experimental data on macroscopic level. Using the proposed coupled plasticity-damage constitutive model, the effect of the micromechanical properties of concrete, such as aggregate shape, distribution, and volume fraction, the ITZ thickness, and the strength of the ITZ and mortar matrix on the tensile behavior of concrete is investigated on 2-D and 3-D meso-scale. As a result of simulation, the tensile strength and thickness of the ITZ is the most important factor that control the global strength and behavior of concrete, and the aggregate shape and volume fraction has somewhat effect on the tensile behavior of concrete while the effect of the aggregate distribution is negligible. Furthermore, using the proposed constitutive model, the pull-out analysis of the single straight and curved CNT embedded in cement matrix is carried out. In consequence of the analysis, the interfacial fracture energy is the key parameter governing the CNT pull-out strength and ductility at bonding stage, and the Young's modulus of the CNT has also great effect on the pull-out behavior of the straight CNT. In case of the single curved CNT, while the ultimate pull-out force of the curved CNT at sliding stage is governed by the initial sliding force when preexisting normal force is relatively high, the ultimate pull-out force, when the preexisting normal force is not significant, is increased linearly proportional to the curvature and the Young's modulus of the CNT due to the additionally induced normal force by the bending stiffness of the curved CNT.

The objective of this research project is to investigate novel concepts of determining fibre assembly mechanical properties at woven fabric at meso-scale, viz. yarns and unit-cell. In order to carry out this investigation three instruments were developed and these are presented in subsequent chapters of this thesis. Initially, an instrument was built in order to explore the buckling technique on yarns and fabrics. The data obtained was converted into pure bending output through a proposed non-linear planar elastica model. It was found that the data obtained were in agreement with data obtained from other measuring technique already available in the industry, viz. Pure Bending tester (KES FB2) from the Kawabata Evaluation System. This investigation also found that the buckling technique offers some advantages when compared with the bending tester. Furthermore, the yarn compression method was also explored. A Yarn Compression tester (YCT) was developed in order to carry out this study. This instrument induces transverse compression upon the yarn by means of a probe, which results in a compression versus thickness curve. An, additional feature was introduce on the YCT, such as the use of a digital camera that allows the yarn lateral spreading to be determined as the yarn is compressed. This feature may be used to calculate the Poisson’s ratio, which can be used as an input value for future compression models. Good agreement was found between the proposed yarn compression technique and data obtained from the Kawabata compression tester.Finally, yarn torsional technique was explored by means of developing a Yarn Torsion tester (YTT). It was found that data obtained for this instrumentation were in agreement with a linear model proposed by Postle et al. This investigation may allow future research to continue by means of proposing a torsion mathematical model.

Parallel Kinematic Mechanisms (PKMs) are well suited for high-accuracy applications such as meso-milling. However, drawbacks such as limited platform tilting angle and high configuration dependency of stiffness often limit their usage. In this Thesis, a new six degree-of-freedom (dof) PKM architecture based on a 3×PPRS topology is proposed, in order to address these problems. The new PKM is presented, and its inverse kinematics and Jocobian matrix are derived. The kinematic relations are incorporated into MATLAB to calculate the workspace of the PKM. The stiffness of the new PKM is obtained using Finite Element Analysis (FEA), and configuration dependency of stiffness is investigated. The proposed new mechanism is compared with three similar existing 6-dof PKMs, and it is shown that the new PKM exhibits higher stiffness. Lastly, three meso-Milling Machine Tool prototypes were designed and built. In particular, Prototype III is based on the new mechanism.

Parallel Kinematic Mechanisms (PKMs) are well suited for high-accuracy applications such as meso-milling. However, drawbacks such as limited platform tilting angle and high configuration dependency of stiffness often limit their usage. In this Thesis, a new six degree-of-freedom (dof) PKM architecture based on a 3×PPRS topology is proposed, in order to address these problems. The new PKM is presented, and its inverse kinematics and Jocobian matrix are derived. The kinematic relations are incorporated into MATLAB to calculate the workspace of the PKM. The stiffness of the new PKM is obtained using Finite Element Analysis (FEA), and configuration dependency of stiffness is investigated. The proposed new mechanism is compared with three similar existing 6-dof PKMs, and it is shown that the new PKM exhibits higher stiffness. Lastly, three meso-Milling Machine Tool prototypes were designed and built. In particular, Prototype III is based on the new mechanism.

This thesis describes the synthesis and characterisation of new examples of meso-n1-organometallic porphyrins. These porphyrins were originally encountered as catalytic intermediates in the C-C bond forming reaction on the porphyrin periphery using palladium catalysts. They have now become a research topic in their own right and no other examples of this type of organometallic porphyrins had been reported at the outset of this work. In Chapter 2, several examples of meso-palladioporphyrins were prepared in high yield using oxidative addition of the porphyrin-bromine bond to a suitable Pd(0)phosphine precursor. These phosphine precursors were prepared from Pd(PPh3)4 or Pd2dba3 plus either PPh3 or a chelating diphosphine. Several new examples of mono- and di palladium complexes of chelating diphosphines were prepared. Chapter 3 looks at the preparation of meso-platinioporpyrins and the insertion of various central metal ions into the porphyrin ligand. Pairs of cis- and transisomers of the Pt(II) complexes were isolated from the oxidative addition of Pt(PPh3)3 to the free base and Ni(II) bromoporphyrins. The cis-isomer converted to the trans upon heating. At room temperature the two isomers are geometrically stable and survive unchanged through column chromatography and slow recrystallisation. The central metal ion can be introduced either before or after the oxidative addition to Pt(0). However, it is preferable to insert the metal ion last as the complexes of Br(MDPP) are rather insoluble (especially that of MnCl) and are more difficult to handle than the common intermediate trans- [PtBr(H2DPP)(PPh3)2]. The oxidative addition of Pt(dba)2 to meso-bromo-DPP in the presence of PPh3 has also been shown to be an effective method of synthesising n1-organo platinum porphyrins in high yield. However, this method was unsuccessful when using chelating diphosphines. In Chapter 4, the physical properties of meso- metalloporphyrins are reported including electrochemistry, fluorescence spectroscopy and crystal structure determinations. The fluorescence intensities of the meso-substituted porphyrins (freebase and zinc complexes) are dramatically reduced in comparison with the unsubstituted porphyrins. This fluorescence quenching is a dramatic example of the "heavy atom effect". Electrochemical measurements of freebase and Ni(II)porphyrins indicate that the organometallic fragment is a strong electron donor. The visible absorption spectra for all Pd(II) and Pt(II) complexes are typical for diarylporphyrins. All groups other than H in the 5- or 5- and 15-positions cause a red shift of the major absorption bands for both the free bases and central-metal complexes. The crystal structure studies of the Pt(II) complexes include the complexes, cis- [PtBr(MDPP)(PPh3)2] (M = H2, Ni), trans-[PtBr(MDPP)(PPh3)2] (M = H2, Ni, Zn and Co), trans-[PtCl(H2DPP)(PPh3)2] and trans-[PtBr(NiDPPBr)(PPh3)2]. In all these structures, the free bases are virtually planar while the metallo derivatives adopt a hybrid of the ruffled and saddled conformations. Chapter 5 contains the initial studies of chiral palladioporphyrins, using three different types of chiral chelating diphosphine ligands. These chiral palladioporphyrins are readily prepared by oxidative addition of the Pd(0) precursor with bromoporphyrin. The asymmetry of the chiral ligand is detectable at the remote B-pyrrole protons in all the chiral complexes as eight doublets are observed in 1H NMR spectra. The chirality of these ligands in the porphyrin complexes induces circular dichroism in the region of the porphyrin electronic absorption. High optical activity is observed for the BINAP complexes.

Climate is one of the most important factors influencing where wine grapes can be grown and the quality of wine produced from those grapes. A plants habitat has a profound influence on its growth and development. The surrounding climatic conditions at both the macro- and meso-scales influence the plant-climate miro-scale interactions. The main study site is the McKenzie Vineyard that is owned by Torlesse Wines. The climatic conditions of the surrounding Waipara region was also studied using climate data from the following vineyards; Canterbury House, River Terrace and Waipara West. The overall aim of this research is to improve understanding of the influence of the climatic environment on grapevine development at the meso- to micro-scale. The main findings of the research were firstly, that the most important climatic factor influencing grapevine development and growth is temperature and secondly that there is variability in the temperature across the Waipara Basin. Future research should be conducted for the entire growth season to gain a better understanding of how temperature influences the development of grapevine over the growing season as a whole.

CLEMENTE, Claudenilson da Silva. Desenvolvimento e aplicação de sistemas nanoestruturados a partir da meso-porfirina derivada do LCC. 2015. 93 f. Tese (Doutorado em química)- Universidade Federal do Ceará, Fortaleza-CE, 2015. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-10-04T17:27:12Z No. of bitstreams: 1 2015_tese_csclemente.pdf: 3478429 bytes, checksum: 6edff28cce737feb15c3d8b2a96f4f9d (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-10-10T19:49:13Z (GMT) No. of bitstreams: 1 2015_tese_csclemente.pdf: 3478429 bytes, checksum: 6edff28cce737feb15c3d8b2a96f4f9d (MD5) / Made available in DSpace on 2016-10-10T19:49:13Z (GMT). No. of bitstreams: 1 2015_tese_csclemente.pdf: 3478429 bytes, checksum: 6edff28cce737feb15c3d8b2a96f4f9d (MD5) Previous issue date: 2015 / Porphyrins are very attractive system to study self-assembly due to its basic structure, chemical and thermal stability, synthetic versatility and important technological applications. This work presents the development of self-assembled systems meso-porphyrin derived from cardanol, the major constituent of the LCC. We were developed Langmuir and Langmuir-Blodgett (LB) thin films and superparamagnetic nanosystems coated with meso-porphyrin. The Langmuir films showed molecular area mean of the 177 Å 2 confirmed by compressibility modulus. The 700 nm band observed in the Langmuir films supports the coexistence of monomers and dimers similar to the spectra of the solution (CHCl3/CH3COOH). The Brewster angle microscopy measurements showed formation of bright block domains with different sizes and shapes for the monolayer that disappears after surface pressure starts to increase. The UV–vis spectra of the Langmuir films and FTIR reflection of the Langmuir–Blodgett films (LB) indicated that the molecules exhibit preferential orientation with the parallel planes to the water (Langmuir) and in the substrate (LB). The LB film of 5 layers showed better response as electrode and has been tested as a promethazine sensor. Magnetic Fe 3 O 4 nanoparticles with an average size of 11 nm were coated with oleic acid layer and a meso-porphyrin layer to producing a novel superparamagnetic fluorescent nanosystem. Also were obtained systems coated with meso-porphyrins metallated with Co2+, Ni2+, Cu2+ and Zn2+ ions. The systems were characterized by TEM, FT-IR, TGA, vibrating sample magnetometry, UV-Vis, fluorescence and confocal miscroscopy. The systems showed good thermal stability, excellent magnetization and nanosized dimensions. / Porfirinas são sistemas muito atrativos para estudos de automontagem graças a suaestrutura ba se, estabilidadequímica e térmica, versatilidade sintética e importantes aplicações tecnológicas. Este trabalho tem por finalidade apresentar o desenvolvimento de sistemas automontados da meso-porfirina derivada do cardanol, constituinte majoritário do LCC. Foram desenvolvidos filmes finos de Langmuir e Langmuir-Blodgett (LB) e aplicado como sensor eletroquímico para prometazina e nanossistemas superparamagnéticos revestidos com a meso-porfirina. Os filmes de Langmuir apresentaram área molecular média de 177 Å 2 , confirmado pelo módulo de compressibilidade. A banda centrada em λ = 700 nm observados nos filmes suporta a coexistência de monômeros e dímeros semelhantes aos espectros em solução de CHCl3/CH3COOH. A microscopia do ângulo de Brewster mostrou domínios com blocos brilhantes de diferentes tamanhos e formas para a monocamada que desapareceram após o aumento da pressão de superfície. Os espectros de UV-vis dos filmes e FT-IR no modo reflexão dos filmes de Langmuir-Blodgett (LB) indicaram que as moléculas apresentam orientação preferencial com os planos paralelos à água (no Langmuir) e no substrato (LB). O filme LB de 5 camadas apresentou melhor resposta como eletrodo e foi testado como um sensor de prometazina. As nanopartículas magnéticas de Fe 3 O 4 com tamanho médio de 11 nm foram revestidos com uma camada de ácido oleico seguido da meso-porfirina produzindo um novo nanossistema superparamagnético fluorescente. Foram obtidos também os sistemas revestidos com porfirinas metaladas com os íons Co2+, Ni2+, Cu2+ e Zn2+, os quais foram caracterizados por MET, FT-IR, análise termogravimétrica, magnetometria de amostra vibrante, UV-Vis, emissão de fluorescência e miscroscopia confocal. Os resultados mostraram que os sistemas apresentaram boa estabilidade térmica, comportamento superparamagnético e dimensões nanométricas.

Made available in DSpace on 2014-06-12T18:04:25Z (GMT). No. of bitstreams: 2 arquivo3923_1.pdf: 7672485 bytes, checksum: e558a60e63cdcf8f7048c9c8a9063e0f (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Novos dados quimioestratigráficos para duas unidades Mesoproterozoicas e uma Neoproterozóica do Terreno Nico Perez somam-se a coluna estratigráfica do Uruguai. O Grupo Carapé integrado pelas Formações: (1) Marco Los Reyes composta de calcário puro, BIFS, arenito, mármores e anfibolito. Rochas carbonáticas desta Formação apresentam valores máximos de δ13C de +5 e duas excursões negativas (-3,2 e - 2,3 ) e 86Sr/87Sr com valores entre 0.707 e 0.710 , sugerindo idade Neoproterozóica, entre 600 e 680 Ma; (2) Mataojo composta de dolomitos calcíticos, meta-arenitos, micaxistos, anfibolitos e gneisses. Apresentam valores de δ13C próximos a 0 , característica de rochas carbonáticas do Mesoproterozico. O Grupo Parque UTE (GPU), uma seqüência metavolcano-sedimentar, é constituído da base para o topo pelas Formações (1) Cañada Espinillo com rochas vulcânicas básicas; (2) Mina Valencia com dolomitos brancos e puros, intercalados com dolomitos cinza e níveis de calcarenitos e calciruditos (tempestitos); (3) Cerro del Mastilcom folhelhos negros carbonáticos, intercalados com rochas calcárias cinza e piroclásticas ácidas. Os valores de δ13C apresentam um plateu positivo entre 1 e 1,5 e duas excursões negativas (-1 e -3 ) que sugerem idade Mesoproterozica, e que é coerente com dados radiométricos de U-Pb em zircão de 1422 ± 21Ma dos riolitos do topo e idades de 1492 ± 21 Ma em gabros da base. Este estudo confirma a importância do conhecimento da geologia do craton do Rio de La Plata para a compreensão da evolução do Gondwna durante este intervalo de tempo da história geológica da Terra

Heterogeneous landscapes made up of variegated patches are common among managed ecosystems, and often provide diverse structural and compositional habitat characteristics. Landscape heterogeneity can affect distribution of resources, competition, and dispersal of organisms over space and time. Therefore, understanding how species respond to dynamic landscapes is necessary when implementing management decisions that foster biodiversity within managed ecosystems. My study uses hierarchical models in a Bayesian framework to quantify effects of landscape context on meso-mammal predators and northern bobwhite (Colinus virginianus) occupancy in an intensively managed loblolly pine forest. Results indicate that edge density can positively influence occupancy of meso-mammal predators, while age of stand, or years since disturbance, can negatively influence occupancy of northern bobwhite. These results further illustrate the importance of considering biodiversity implications when making management decisions.