Short and long fatigue crack growth in a SiC reinforced aluminium alloy

Fatigue crack growth behaviour in a 15 wt% SiC particulate reinforced 6061 aluminium alloy has been examined using pre-cracked specimens. Crack initiation and early growth of fatigue cracks in smooth specimens has also been investigated using the technique of periodic replication. The composite contained a bimodal distribution of SiC particle sizes, and detailed attention was paid to interactions between the SiC particles and the growing fatigue-crack tip. At low stress intensity levels, the proportion of coarse SiC particles on the fatigue surfaces was much smaller than that on the metallographic sections, indicating that the fatigue crack tends to run through the matrix avoiding SiC particles. As the stress intensity level increases, the SiC particles ahead of the growing fatigue crack tip are fractured and the fatigue crack then links the fractured particles. The contribution of this monotonic fracture mode resulted in a higher growth rate for the composite than for the unreinforced alloy. An increase in the proportion of cracked, coarse SiC particles on the fatigue surface was observed for specimens tested at a higher stress ratio.

Square and compass: Freemasonry's tools for constructing a global civil society

The concept of a global civil society is gaining greater acceptance among International Relations (IR) scholars, yet few studies exist that look at the role of fraternal organizations and their influence in constructing this realm. Freemasonry, one of the oldest fraternal orders, exerts a powerful influence on its membership through its symbolism, architecture and ritual, based on the tenets of mutual respect and tolerance towards all human beings. Such principles helped in creating a body of practices and institutions as early as the eighteenth century which two hundred years later were identified and conceptualized as global civil society. ^ The allegations of anti-Masons and conspiracy theorists offer a continuous account of Masonry's influence on the political scene since its modern founding in 1717 Great Britain. Conspiracy theorists portray the coming of a New World Order, orchestrated and directed by a secret hierarchy of Masons/Illuminati. Even though the lens of conspiracy theories paints a distorted view of reality, it does focus attention to Freemasonry's activities as a major player in politics over the span of three centuries. Not only do such theories challenge the novelty of practices that make up a global civil society, but also the notion that it is an inclusive and growing sector that unites people across the globe. They also provide a valuable critique by pointing out the inconsistencies and discriminatory practices of Masonry as contrasted with the lofty ideals and aims for humanity. ^ The Masonic influence in the social world is perceived as one that reflects the liberal worldview where the nation-state and power structures are in pursuit of human progress, or profit. The symbolism of Masonry, however, carries a message that can be characterized as representing republican ideals. Masonic symbolism and ritual create spaces of meaning where the contradictions between the ideals and the structures of inequality and elitism can be resolved. Freemasonry as a symbolic system proclaiming their inherent republican values does have a global reach. However, the effectiveness of these values is bounded by the constraints that are inherent in a liberal world dominated by nation-states. ^

Estudo da incorporação de resíduos de perfuração para aplicação em cimentação de poços de petróleo

During the drilling of oil and natural gas are generated solid waste, liquid and gaseous. These solid fragments, which are known as cuttings, are carried to the surface through the drilling fluid. Furthermore, this fluid serves to cool the bit, keeping the internal pressure of the well, and others. This solid residue is very polluting, because it has incorporated beyond the drilling fluid, which has several chemical additives harmful to the environment, some heavy metals that are harmful to the environment, such as lead. To minimize the residue generated, are currently being studied numerous techniques to mitigate the problems that such waste can cause to the environment, like addition of cuttings in the composition of soil cement brick masonry construction, addition of cuttings on the clay matrix for the manufacture of solid masonry bricks and ceramic blocks and coprocessing of the cuttings in cement. So, the main objective of this work is the incorporation of cuttings drilling of oil wells, the cement slurry used in the cementing operation of the well. This cuttings used in this study, arising from the formation Pendências, was milled and separated in a sieve of 100 mesh. After grinding had a mean particle sike in order of 86 mm and crystal structure containing phases of quartz and calcite type, characteristic of the Portland cement. Were formulated and prepared slurries of cement with density 13 lb / gal, containing different concentrations of gravel, and realized characterization tests API SPEC 10A and RP 10B. Free water tests showed values lower than 5.9% and the rheological model that best described the behavior of the mixtures was the power. The results of compressive strength (10.3 MPa) and stability (Dr <0.5 lb / gal) had values within the set of operational procedures. Thus, the gravel from the drilling operation, may be used as binders in addition to Portland cement oil wells, in order to reuse this waste and reduce the cost of the cement paste.

Desempenho zootécnico dos camarões: Litopenaeus vannamei e Macrobrachium rosenbergii em tanques rede e aquicultura familiar na comunidade de Bebida-Velha, RN

The study aims to evaluate the performance and identify lesions of agonistic interactions of Macrobrachium rosenbergii in different densities cages (chapter 1); compare the growth performance of shrimp M. rosenbergii and Litopenaus vannamei cages (chatper 2); in addition the study aimed at identifying the knowledge and practices of a traditional community of farmers Bebida-Velha, in the city of Pureza / RN, practicing rural family and aquaculture, as well as tracing the community socioeconomic profile and evaluate the management that these farmers use in shrimp farming Macrobrachium rosenbergii (chapter 3). To perform the experiments (chapter 1 and 2) shrimp species L. vannamei and M. rosenbergii were weighed on a digital scale and transferred to cultures in cages. The cages had 1m³, with 5mm mesh between us and were closed on top with screen to avoid predators (birds, insects). The animals remained in adaptation for fifteen days before the start of data collection (each experiment). Both experiments lasted seventy days, totaling eighty-five days cultivation. During the cultures, animals were fed pelleted feed for shrimp at 10% of their biomass with 35% crude protein, offered in feed trays twice a day during the hours (7:00 am and 14:00 pm). The remnants in the tray were removed after 2h of permanence to calculate intake. To determine the performance parameters, some samples were taken every 10 days. The results of both experiments were analyzed using the STATISTIC 7.0 (2004). In Chapter 1 experiment were applied5 treatments were applied with 5 replications each: D5 - 5 animals/m2 ; D10 - 10 animals/m2 ; D15 - 15 animals/m2 ; D20 - 20 animals/m2 ; D25 - 25 animals/m2 . To this, were distributed 25 cages randomly in two masonry nurseries. The end of the experiment the lesions were verified and quantified. The chapter 2 experiment began when the shrimp reached the same age (eighty-four days) and was used the density of 25 shrimp / m2 with 4 repetitions. For the realization of chapter 3 were applied semi-structured interviews by direct approach of Bebida Velha of settlers practicing aquaculture activity, tilapia producers and community shrimp. Data were tabulated and analyzed according to the responses obtained by the participants. Therefore, the amount of damage increased with increasing stocking density. The density of 10 freshwater shrimp/m² showed the best conditions for a better performance in cages. It can be concluded that in cages, the cultivation of species of fresh water shrimp M. rosenbergii had better zootechnical indexes than the cultivation of marine shrimp species L. 9 vannamei. It was possible to verify that the activities of which the interviewees practice guarantee a good quality of life and income for them. We find that respondents have traditional and local knowledge, and also may be interested in the cultivation of the species M. rosenbergii.

Modelagem computacional para avaliação da interação entre painéis de alvenaria e estrutura de suporte em concreto armado

The developed study proposes a new computer modeling efficient and easy to apply in usual project situations to evaluate the interaction between masonry panels and support structure. The proposed model simulates the behavior of the wall exclusively using frame finite elements, thus compounding an equivalent frame. The validation was performed in two ways: firstly, through the analysis of various panels of generic plans, comparing the results obtained from equivalent frame model with the ones from a reference model, which uses shell finite elements in discretization of the walls; and in a second step, comparing with the results of the experimental model of Rosenhaupt. The analyzes considered the linear elastic behavior for materials and consisted basically in the evaluation of vertical displacements and efforts in support beams, and tensions at the base of walls. Was also evaluated, from flat and threedimensional modeling of some walls from a real project, important aspects of the wall-beam interaction, e.g.: the presence of openings of doors and windows, arranged in any position; conditions of support and linking of beams; interference of moorings between walls; and consideration of wind action. The analysis of the achieved results demonstrated the efficiency of the proposed modeling, since they have very similar aspects in the distribution of stresses and efforts, always with intensities slightly larger than those of the reference and experimental models.

Revestimento decorativo monocamada pigmentado, com resíduo de vidro temperado, para aplicação em fachadas

Although efficient from a technical point of view, mortar layers that make up the traditional masonry coating (slurry mortar, plaster and plaster) have to be in contradiction with the new construction technologies and more efficient methods of consumption and work rationalization. From an environmental point of view, the recovery of waste into new composites for the building has been a growing strand of studies in the scientific community, may prove to be a cost-effective solution in some cases. Thus, this research proposes the development of a mortar Decorative Coating Monolayer (RDM), for use in facades, produced on site, incorporating tempered glass waste (RVT) in the cement matrix, as a partial substitute for aggregate. Therefore, we adopted the binder respect / aggregate of 1: 6 (by volume), consistency index 250mm ± 20, sand substitution levels of glass waste 20%, 50% and 80% and relative water / cement varied in many traits. Two additives were used, a polymer, styrene-butadiene-based, and other chemical, besides mineral and silica fume inorganic pigment in colors red, yellow and blue. Mechanical tests were carried out on fresh pasta and hardened, as well as for the applied coating on masonry, so as to demonstrate the feasibility of the material. In addition, it verified the adequacy of the RDM built environment by means of thermal tests. The results demonstrated the feasibility of the proposed RDM with significantly higher values when compared to norms, especially the dash-added replacement content of 20% and addition of pigment in red. Therefore, the study shows the scientific community as an incentive to the use of technological innovations in construction, increasing the range of alternatives available for housing production, with the proposition of a material that achieves the desired functionality and obtain environmental gain, and may be adopted on construction sites as an alternative industrialized mortars.

Semi-engineered earthquake-resistant structures: one-storey buildings built up with gabion-box walls

This thesis studies the static and seismic behavior of simple structures made with gabion box walls. The analysis was performed considering a one-story building with standard dimensions in plan (6m x 5m) and a lightweight timber roof. The main focus of the present investigation is to find the principals aspects of the seismic behavior of a one story building made with gabion box walls, in order to prevent a failure due to seismic actions and in this way help to reduce the seismic risk of developing countries where this natural disaster have a significant intensity. Regarding the gabion box wall, it has been performed some calculations and analysis in order to understand the static and dynamic behavior. From the static point of view, it has been performed a verification of the normal stress computing the normal stress that arrives at the base of the gabion wall and the corresponding capacity of the ground. Moreover, regarding the seismic analysis, it has been studied the in-plane and out-of-plane behavior. The most critical aspect was discovered to be the out-of-plane behavior, for which have been developed models considering the “rigid- no tension model” for masonry, finding a kinematically admissible multiplier that will create a collapse mechanism for the structure. Furthermore, it has been performed a FEM and DEM models to find the maximum displacement at the center of the wall, maximum tension stresses needed for calculating the steel connectors for joining consecutive gabions and the dimensions (length of the wall and distance between orthogonal walls or buttresses) of a geometrical configuration for the standard modulus of the structure, in order to ensure an adequate safety margin for earthquakes with a PGA around 0.4-0.5g. Using the results obtained before, it has been created some rules of thumb, that have to be satisfy in order to ensure a good behavior of these structure.

RELIBILITY ANALYSIS OF SIMPLE SLOPES AND SOIL-STRUCTURES WITH LINEAR LIMIT STATES

The first objective of this research was to develop closed-form and numerical probabilistic methods of analysis that can be applied to otherwise conventional methods of unreinforced and geosynthetic reinforced slopes and walls. These probabilistic methods explicitly include random variability of soil and reinforcement, spatial variability of the soil, and cross-correlation between soil input parameters on probability of failure. The quantitative impact of simultaneously considering the influence of random and/or spatial variability in soil properties in combination with cross-correlation in soil properties is investigated for the first time in the research literature. Depending on the magnitude of these statistical descriptors, margins of safety based on conventional notions of safety may be very different from margins of safety expressed in terms of probability of failure (or reliability index). The thesis work also shows that intuitive notions of margin of safety using conventional factor of safety and probability of failure can be brought into alignment when cross-correlation between soil properties is considered in a rigorous manner. The second objective of this thesis work was to develop a general closed-form solution to compute the true probability of failure (or reliability index) of a simple linear limit state function with one load term and one resistance term expressed first in general probabilistic terms and then migrated to a LRFD format for the purpose of LRFD calibration. The formulation considers contributions to probability of failure due to model type, uncertainty in bias values, bias dependencies, uncertainty in estimates of nominal values for correlated and uncorrelated load and resistance terms, and average margin of safety expressed as the operational factor of safety (OFS). Bias is defined as the ratio of measured to predicted value. Parametric analyses were carried out to show that ignoring possible correlations between random variables can lead to conservative (safe) values of resistance factor in some cases and in other cases to non-conservative (unsafe) values. Example LRFD calibrations were carried out using different load and resistance models for the pullout internal stability limit state of steel strip and geosynthetic reinforced soil walls together with matching bias data reported in the literature.

Francisco Franco, articulista de incógnito (1945–1960)

Se trata de un análisis pormenorizado de los artículos publicados por Francisco Franco en el periódico Arriba entre los años 1945 y 1960 bajo los seudónimos de Jakim Boor, Hispanicus y Macaulay. Se lleva a cabo su disección en dos grandes categorías: enemigos del Régimen y política, economía y sociedad. Para ello, se toma como ejemplo el propio artículo de Hispanicus titulado “Lo político, lo económico y lo social”. En la primera de las dos grandes categorías se agrupan todos aquellos elementos abstractos -instituciones o ideologías- que Franco consideraba perjudiciales para la España que él gobernaba o que históricamente habían sido hostiles a este país; en la segunda se recogen el comentario sobre política en términos actuales o generales, las situaciones económicas y sociales así como los numerosos fragmentos de Historia de España que el dictador gustaba de incluir en sus colaboraciones periodísticas.

Arquitectura em Terra

A presente dissertação tem como tema central um modelo construtivo de arquitectura em terra, designadamente o tabique. Este modelo construtivo ancestral de alvenarias reserva na sua génese inúmeras particularidades, que vão desde as mais variadas formas de concepção do modelo por parte dos diferentes povos espalhados pelo mundo aos valiosos contributos sociais e ambientais. Na sua essência, o tabique foi muito utilizado por pessoas de parcos recursos económicos em soluções, por vezes muito engenhosas, levando-as a recorrer à mãe natureza para extrair dela os materiais necessários para a construção das suas casas. Um pouco por todo o mundo existem exemplares deste modelo tradicional contribuindo activamente para o enriquecimento dum vasto espólio de arquitectura em terra, matéria esta que tem vindo a ganhar um novo alento de acordo com as actuais “políticas" ecológicas. Deste modo e ao abrigo dos princípios gerais da conservação e restauro do património, o tabique detém informação relevante no que respeita à sustentabilidade do planeta, tornando o tema mais apelativo ao debate e à planificação de novas acções, envolvendo cada vez mais os profissionais em prol de um objectivo que garanta ao planeta um futuro mais próspero e equilibrado.

Projeto de reforço de um edifício de habitação

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Estruturas

A petrographic investigation into the durability of common replacement sandstones to the crystallisation of de-icing salts

Scottish sandstone buildings are now suffering the long-term effects of salt-crystallisation damage, owing in part to the repeated deposition of de-icing salts during winter months. The use of de-icing salts is necessary in order to maintain safe road and pavement conditions during cold weather, but their use comes at a price. Sodium chloride (NaCl), which is used as the primary de-icing salt throughout the country, is a salt known to be damaging to sandstone masonry. However, there remains a range of alternative, commercially available de-icing salts. It is unknown however, what effect these salts have on porous building materials, such as sandstone. In order to protect our built heritage against salt-induced decay, it is vital to understand the effects of these different salts on the range of sandstone types that we see within the historic buildings of Scotland. Eleven common types of sandstone were characterised using a suite of methods in order to understand their mineralogy, pore structure and their response to moisture movement, which are vital properties that govern a stone’s response to weathering and decay. Sandstones were then placed through a range of durability tests designed to measure their resistance to various weathering processes. Three salt crystallisation tests were undertaken on the sandstones over a range of 16 to 50 cycles, which tested their durability to NaCl, CaCl2, MgCl2 and a chloride blend salt. Samples were primarily analysed by measuring their dry weight loss after each cycle, visually after each cycle and by other complimentary methods in order to understand their changing response to moisture uptake after salt treatment. Salt crystallisation was identified as the primary mechanism of decay across each salt, with the extent of damage in each sandstone influenced by environmental conditions and pore-grain properties of the stone. Damage recorded in salt crystallisation tests was ultimately caused by the generation of high crystallisation pressures within the confined pore networks of each stone. Stone and test-specific parameters controlled the location and magnitude of damage, with the amount of micro-pores, their spatial distribution, the water absorption coefficient and the drying efficiency of each stone being identified as the most important stone-specific properties influencing salt-induced decay. Strong correlations were found between the dry weight loss of NaCl treated samples and the proportion of pores <1µm in diameter. Crystallisation pressures are known to scale inversely with pore size, while the spatial distribution of these micro-pores is thought to influence the rate, overall extent and type of decay within the stone by concentrating crystallisation pressures in specific regions of the stone. The water absorption determines the total amount of moisture entering into the stone, which represents the total amount of void space for salt crystallisation. The drying parameters on the other hand, ultimately control the distribution of salt crystallisation. Those stones that were characterised by a combination of a high proportion of micro-pores, high water absorption values and slow drying kinetics were shown to be most vulnerable to NaCl-induced decay. CaCl2 and MgCl2 are shown to have similar crystallisation behaviour, forming thin crystalline sheets under low relative humidity and/or high temperature conditions. Distinct differences in their behaviour that are influenced by test specific criteria were identified. The location of MgCl2 crystallisation close to the stone surface, as influenced by prolonged drying under moderate temperature drying conditions, was identified as the main factor that caused substantial dry weight loss in specific stone types. CaCl2 solutions remained unaffected under these conditions and only crystallised under high temperatures. Homogeneous crystallisation of CaCl2 throughout the stone produced greater internal change, with little dry weight loss recorded. NaCl formed distinctive isometric hopper crystals that caused damage through the non-equilibrium growth of salts in trapped regions of the stone. Damage was sustained as granular decay and contour scaling across most stone types. The pore network and hydric properties of the stones continually evolve in response to salt crystallisation, creating a dynamic system whereby the initial, known properties of clean quarried stone will not continually govern the processes of salt crystallisation, nor indeed can they continually predict the behaviour of stone to salt-induced decay.

PRODUÇÃO DE MUDAS DE UMBUZEIRO ( Spondias tuberosa Arruda Câmara) EM DIFERENTES SUBSTRATOS E TAMANHO DE RECIPIENTES

A espécie Spondias tuberosa Arr. Cam. (umbuzeiro) destaca-se como uma das espécies arbóreas de maior potencial do semiárido brasileiro. Apesar de sua relevante importância socioeconômica e ambiental, há falta de estudos voltados para o estabelecimento de um modelo de produção de mudas da espécie. O objetivo desse trabalho foi avaliar a produção de mudas de Spondias tuberosa utilizando diferentes substratos e tamanho de recipientes. O experimento foi conduzido no viveiro do Laboratório de Ecologia Vegetal (LEV) do Centro de Ciências Agrárias (CCA) da Universidade Federal da Paraíba (UFPB), Areia - PB. O delineamento experimental usado foi em blocos casualizados em esquema fatorial 2 x 7 e parcelas subdivididas, sendo que os recipientes representaram as parcelas e os substratos as subparcelas. Foram utilizados substratos formulados a partir da mistura de terra de subsolo (37,5-100%), areia lavada (12,5- 25%) e esterco bovino curtido (10-50%). Os recipientes utilizados foram sacos de polietileno preto com volumes de 1900 cm3 (15 x 27 cm) e 5000 cm3 (25 x 26 cm). Para a obtenção das plântulas, sementes de Spondias tuberosa foram semeadas em sementeira de alvenaria até a repicagem (90 dias após o semeio). Aos 78 dias, após a repicagem, as mudas foram avaliadas quanto à altura, diâmetro do colo, relação altura/ diâmetro do colo, diâmetro do xilopódio, comprimento de raiz, massa seca da parte aérea e raiz. Os dados obtidos foram submetidos à análise de variância e ao teste F, sendo as médias comparadas pelo teste de Tukey ao nível de 5% de probabilidade, utilizando o software SISVAR®. Os substratos com esterco bovino curtido proporcionaram os maiores valores em altura e comprimento de raiz. Para a produção de mudas de Spondias tuberosa, é recomendado o substrato contendo terra de subsolo (45%) + Areia (15%) + Esterco bovino (40%).

Avaliação de Ciclo de Vida Energético (ACVE) de sistemas de vedação de habitações

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2015.

Reforço sísmico de estruturas em adobe

A construção em alvenaria de adobe tem um vasto património a nível mundial. É possível encontrar construção em terra no nosso território, sendo que a técnica particular do adobe foi amplamente utilizada na região de Aveiro durante o século XIX até meados do século XX. Devido à tradição e valor patrimonial da construção em alvenaria de adobe, diversos trabalhos têm vindo a ser desenvolvidos no departamento de Engenharia Civil da Universidade de Aveiro, perspetivando um aprofundar de conhecimentos acerca deste tipo de construção. A vulnerabilidade sísmica das construções em alvenaria de adobe fez com que surgissem vários estudos para caracterização sísmica das mesmas, sendo que, recentemente, foi levada a cabo a realização de um ensaio cíclico, simulando os efeitos de um sismo, num modelo de adobe à escala real, construído no laboratório do departamento de Engenharia Civil da Universidade de Aveiro. A presente dissertação tem como objetivo estudar formas de reparação e reforço sísmico de estruturas em adobe. Para isso foi reparado e reforçado o modelo previamente ensaiado, e novamente submetido a um ensaio cíclico, de modo a fazer-se uma análise comparativa com o ensaio prévio e assim retirar conclusões sobre a eficácia da solução de reforço aplicada.