O século 21 vem sendo caracterizado pela urbanização acelerada em países economicamente emergentes. O aumento das construções em áreas urbanas, quando mal planejado, ocasiona problemas estruturais e espaciais que afetam diretamente os cidadãos e seu entorno. Muitas pesquisas científicas propõem métodos para monitorar a qualidade dos materiais utilizados em obras de engenharia. As inspeções de qualidade mais aplicadas são feitas em materiais relacionados à estrutura, como o concreto. Todo o concreto utilizado em obra é obrigatoriamente submetido ao ensaio à compressão axial, que rompe os corpos-de-prova. Estes ensaios destrutivos não são realizados in loco e todo o material utilizado é descartado após análise. Neste sentido, o sensoriamento remoto pode ser utilizado no mapeamento e monitoramento de materiais de construção, permitindo investigar e identificar diversos componentes de forma não-destrutiva. Os materiais podem ser inspecionados diretamente no local da obra, de uma forma rápida, não-invasiva e de baixo custo, características imprescindíveis no processo contínuo da construção civil. Neste trabalho foi utilizado o equipamento espectrorradiômetro FieldSpec 3 para medir materiais cimentícios à base de cimento Portland (pasta de cimento, argamassa e concreto). Nas amostras de pasta de cimento e argamassa, analisou-se o comportamento espectral de quatro diferentes resistências mecânicas e nas amostras de concreto avaliou-se a diferença entre o comportamento espectral de concretos submetidos a carregamento precoce e concretos de referência. As curvas espectrais geradas pelo registro da radiação eletromagnética refletida e absorvida das amostras foram interpretadas com base na teoria de espectroscopia vibracional e eletrônica. Esta dissertação tem um caráter inovador e a técnica aplicada é extremamente promissora e praticável como um método alternativo. Na literatura não existem estudos que já fizeram esta investigação, nem trabalhos acadêmicos com o propósito de diferenciar resistências mecânicas a partir da análise e interpretação de assinaturas espectrais destes materiais. O objetivo deste trabalho é mostrar uma técnica auxiliar inédita para analisar corpos-de-prova sólidos, utilizando a espectroscopia no visível e infravermelho próximo. O resultado deste estudo constatou que as amostras de pasta e de argamassa apresentaram contraste espectral e detectou a presença e proporção de água nas amostras. Também identificaram-se diferenças entre o comportamento espectral dos concretos de referência e o dos pré-carregados, evidenciando-se a aplicabilidade desta ferramenta na identificação da microfissuração do concreto. Com auxílio da transformada de wavelet foi possível comprovar estatisticamente o contraste espectral e que a profundidade das feições de absorção da água é inversamente proporcional à resistência mecânica, para materiais cimentícios como a pasta e argamassa. A técnica apresentada foi considerada bastante promissora como ferramenta auxiliar na avaliação da qualidade de materiais cimentícios à base de cimento Portland. / The 21st century has been characterized by rapid urbanization in economically emerging countries. The increase of constructions in urban areas, when not planned correctly, causes structural and spatial problems that directly affect citizens and their surroundings. Many scientific researches propose methods to monitor the quality of materials used in engineering works. The quality inspections more applied are made in materials related to the structure, like concrete. All the concrete used in the side work must be submitted to axial compression test, which breakes the samples. These destructive tests are not done in loco and all the material used is discarded after analysis. This way, the remote sensing can be used for mapping and monitoring of construction materials, allowing to investigate and to identify many components in a non-destructive way. The materials can be inspected directly inside the side work, in a quick way, non-invasive and low cost, indispensable characteristics in the ongoing process of civil construction. In this work a piece of equipment FieldSpec 3 spectroradiometer was used to measure cement materials based on Portland cement (cement paste, mortar and concrete). In the cement paste and mortar samples was analyzed the spectral behavior of four different compressive strengths and in the concrete samples was analyzed the difference between the spectral behavior of concretes submitted to early loading and concretes of reference. The spectral curves produced by register of electromagnetic radiation reflected and absorbed of the samples were interpreted based on the theory vibrational and electronic spectroscopy. This dissertation is an innovation and the technique applied is extremely promising and feasible as an alternative method. In the literature there are no studies that have already done this research or academic papers with the purpose of differentiate compressive strengths from the analysis and interpretation of their spectral signatures. The objective of this work is to show an original technique to analyze solid samples using the spectroscopy in the visible and near infrared. The result of this study found that the samples of cement past and mortar showed spectral contrast and detected the presence and proportion of water in the samples. Besides it identified differences between the spectral behavior of early loading and concretes of reference, highlighting the applicability of this tool in the identification of the concrete microcracking. With the help of wavelet transform was possible to prove statistically the spectral contrast and that the depth of water absorption features is inversely proportional to the compressive strength, for cement materials such as paste and mortar. The technique presented was considered very promising as an assistant technique in quality appraisal of cement material based on Portland cement, may complement information obtained by conventional techniques.

Between the years 2013 and 2016, e-commerce sales grew as a percent of total retail sales in the United States from 5.8% to 8.5%, an increase of $129 billion. Some brick-and-mortar (B & M) retailers struggle with maintaining the historic levels of revenue in their stores. A multiple case study design with retail store managers was used to understand what factors engage customers to shop at B & M store locations. The consumer-dominant value creation logic was the conceptual framework. Data were collected from semistructured interviews with 5 retail store managers in Texas who demonstrated successful strategies for engaging customers in their B & M stores, and notes from observations. Data from semistructured interviews were analyzed with a traditional method to identify themes. The found themes included fun at work, customer connection, relationship, pride, and genuine care. The implications of this study for positive social change include the potential to enhance the economic vitality and development in the surrounding community by creating additional jobs and generating additional income for members of the community that could be spent in local economies.

Cette thèse a permis d’évaluer l’effet des changements de morphologie d’un matériau cimentaire soumis à un traitement thermique jusqu’à T (≤ 400°C). Pour cela, nous avons caractérisé expérimentalement le comportement mécanique (en compression uniaxiale, compression hydrostatique avec ou sans déviateur), poro-mécanique (modules d’incompressibilité Kb, Ks et coefficient de Biot b) et hydraulique (perméabilité au gaz), d’un mortier modèle E/C=0,5 suite à un cycle de chauffage/refroidissement. Les essais mécaniques multiaxiaux sont couplés aux mesures de perméabilité, qui servent d’indicateur de la progression de la fissuration du matériau sous contrainte. Nous avons également mis au point un essai original, permettant de quantifier le volume de l’espace poreux interconnecté sous chargement hydrostatique Pc. La création de porosité occluse sous l’effet d’un accroissement du confinement est confirmée, et ainsi la diminution de la rigidité de la matrice solide Ks avec Pc après traitement thermique T>200°C. Nous avons également identifié un effet bouchon (aucun passage de gaz) lors d’un chargement couplé, thermique et en compression hydrostatique du mortier mais aussi de bétons industriels (CERIB et ANDRA). Afin d’analyser l’évolution des propriétés mécaniques et poro-élastiques après traitement thermique, un modèle prédictif thermo-élasto-plastique avec endommagement isotrope et une approche micro-mécanique descriptive, intégrant la présence de micro-fissures, y sont couplés / This work investigates the effects of morphological changes of a cement-based material subjected to heat treatment (up to 400°C). For a model W/C=0.5 mortar, we have characterized experimentally hydraulic behaviour (gas permeability), mechanical behaviour (in uniaxial compression, hydrostatic compression with or without deviatoric stress) and poro-mechanical behaviour (incompressibility moduli Kb, Ks and Biot’s coefficient b) after a heating/cooling cycle. We have also developed an original experiment aimed at quantifying the accessible pore space volume under hydrostatic compression. The creation of occluded porosity under high confinement is confirmed, which justifies the observed decrease of solid matrix rigidity Ks under high confinement. A gas retention phenomenon was identified under simultaneous thermal and hydrostatic loadings for mortar, and industrial concretes (provided by CERIB and ANDRA). A predictive thermo-elasto-plastic model with isotropic damage and a micro-mechanical approach, which represents micro-cracking, are coupled in order to analyze or predict the evolution of mechanical and poro-elastic properties after heat cycling

A spectral element algorithm for solution of the incompressible Navier-Stokes and heat transfer equations is developed, with an emphasis on extending the classical conforming Galerkin formulations to nonconforming spectral elements. The new algorithm employs both the Constrained Approximation Method (CAM), and the Mortar Element Method (MEM) for p-and h-type nonconforming elements. Detailed descriptions, and formulation steps for both methods, as well as the performance comparisons between CAM and MEM, are presented. This study fills an important gap in the literature by providing a detailed explanation for treatment of p-and h-type nonconforming interfaces. A comparative eigenvalue spectrum analysis of diffusion and convection operators is provided for CAM and MEM. Effects of consistency errors due to the nonconforming formulations on the convergence of steady and time dependent problems are studied in detail. Incompressible flow solvers that can utilize these nonconforming formulations on both p- and h-type nonconforming grids are developed and validated. Engineering use of the developed solvers are demonstrated by detailed parametric analyses of oscillatory flow forced convection heat transfer in two-dimensional channels.

For the period of several centuries, the influence of several distinct cultures produced rich and diverse cultural heritage that we see today in East Africa countries. The most tangible remains of these heritages are stone built buildings and structures including, palaces, mosques, residential houses and tombs. At present, these heritages are in different physical state, some are in relatively good condition while many are in an appalling condition. The presence of these historical monuments has benefited these countries economically and culturally therefore, it is essential to ensure that these monuments continue to exist. Material characterisation of the historical buildings and associated structures was used to develop a suitable method of intervention that is sympathetic to the original materials. Mortar is the most damaged material therefore, historical mortar from Stone Town historical buildings and associated structures has been characterised by visual examination, optical microscopy, x-ray diffraction and hydrostatic weighing and the results have been compared. The historical mortar is mainly comprised of calcite, quartz and feldspar. The mortar condition has been divided into hard mortar, soft mortar and, soft and friable mortar. The deteriorated mortar that required consolidation is soft mortar and, soft and friable mortar with a porosity of approximately 27%. Calcium hydroxide solution (limewater) has been selected as consolidant and the consolidation procedure involves two steps. Firstly a limewater impregnation procedure has been developed and secondly, the effect of limewater treatment has been determined. For the application procedure it has been observed that, when limewater comes into contact with calcium carbonate a precipitation reaction occurs and that is the cause of poor penetration ability of calcium hydroxide solution. Major influencing factors on the penetration ability of calcium hydroxide solution have been established as, application method and absorption capacity of the treated material during the impregnation process. Optimization of the penetration ability of calcium hydroxide solution has been achieved by impregnating from the middle of the impregnated specimen. Sugar has been used to study the influence of additive on enhancing calcium hydroxide solubility. It has been verified that solubility of calcium hydroxide in a solution of sugar is proportional to the amount of sugar in the solution. Porosity and strength tests have been used to study the effectiveness of calcium hydroxide treatment. Under the conditions studied no appreciable change of porosity has been detected. It is postulated that the calcium hydroxide was deposited at the binder/aggregate interface and at the secondary pores. In terms of strength, evidence has been found to suggest the strength increment varies quantitively with the amount of calcite crystals deposited. / QC 20100803

A spectral element algorithm for solution of the incompressible Navier-Stokes and heat transfer equations is developed, with an emphasis on extending the classical conforming Galerkin formulations to nonconforming spectral elements. The new algorithm employs both the Constrained Approximation Method (CAM), and the Mortar Element Method (MEM) for p-and h-type nonconforming elements. Detailed descriptions, and formulation steps for both methods, as well as the performance comparisons between CAM and MEM, are presented. This study fills an important gap in the literature by providing a detailed explanation for treatment of p-and h-type nonconforming interfaces. A comparative eigenvalue spectrum analysis of diffusion and convection operators is provided for CAM and MEM. Effects of consistency errors due to the nonconforming formulations on the convergence of steady and time dependent problems are studied in detail. Incompressible flow solvers that can utilize these nonconforming formulations on both p- and h-type nonconforming grids are developed and validated. Engineering use of the developed solvers are demonstrated by detailed parametric analyses of oscillatory flow forced convection heat transfer in two-dimensional channels.

The application of Global Internet gives birth to a new trading method, electronic commerce (EC). Because EC possesses advantages such as rapid circulation, far-reaching, low cost, and anytime and anywhere etc., the development of EC replaces the information, contacts, and consultation processes in some traditional sales channels and even develops into direct mode of shopping. Tourism products belong to intangible experiential services with characteristics such as heterogeneity, intangibility, and perishability etc., which makes the travel industry an information intensive industry and is very suitable for the development of EC. Resource-based theory is used as a framework to study its application on the travel industry in this research. It is combined with field interviews and case analysis to study the tourism EC. The critical success factors for travel agencies to develop EC are summarized through the analysis and comprehensive comparison of two different types of travel agencies. It is found that the profitability of tourism EC is mainly dominated by cost leading strategy with the differentiation strategy as a supplement. However, the differentiation strategy can attract customers and lock them in; the most important among them is to enhance the added values. Enterprises will transform their organization structure and strategies according to their own characteristics and resources during the development of EC and the tourism industry belongs to information flow intensive industry in which the deployment of EC requires a set of suitable and complete business model to have a high possibility of success. The research results show that ¡§fully understanding customers¡¦ needs¡¨ is the necessary capability to develop EC successfully and customer and member base is the critical success factor. Also, ¡§value creation¡¨ can be achieved through the development of social networks and blog marketing; at the same time, the research also shows that travel agencies are gradually developing cross channel integration in the process of developing electronic commerce: whether it is virtual travel agency moving from virtual to brick and mortar or traditional agency moving from brick and mortar to virtual, they tend to move toward the integration of click-and-mortar. EC is not just simply establishing a web site: it also includes solving problems such as internal process transformation, computerization, networking, and communicating with external resources etc. It bounds to change certain part of work which employees perform currently and induces behavior changes in consumers. The critical point to the success of the tourism EC is how to coordinate so that employees will accept the new work model and consumers will accept new consumption method.

The paper deals with a combination of the Fourier-finite-element method with the Nitsche-finite-element method (as a mortar method). The approach is applied to the Dirichlet problem of the Poisson equation in three-dimensional axisymmetric domains $\widehat\Omega$ with non-axisymmetric data. The approximating Fourier method yields a splitting of the 3D-problem into 2D-problems. For solving the 2D-problems on the meridian plane $\Omega_a$, the Nitsche-finite-element method with non-matching meshes is applied. Some important properties of the approximation scheme are derived and the rate of convergence in some $H^1$-like norm is proved to be of the type ${\mathcal O}(h+N^{-1})$ ($h$: mesh size on $\Omega_a$, $N$: length of the Fourier sum) in case of a regular solution of the boundary value problem. Finally, some numerical results are presented.

The purpose of this study was to determine the cementitious parameters and placement temperature that impact internal sulfate attack in concrete. Concrete structures make up a large percentage of the infrastructure and multifamily housing. Durability is very important. Cements can be formulated to reduce the impact of external environmental exposure such as high salinity from marine environments or high sulfate levels from soils or surface waters. Concrete is also subject to internal attack such as alkali aggregate reaction, (AAR), and delayed ettringite formation, (DEF). This study focused on some of the cement chemistry issues that determine susceptibility of cement to DEF. Expansion due to DEF can weaken the concrete matrix resulting in microcracks that in some cases may progress to severe matrix cracking. The end result is loss of load carrying capacity and costly repairs. In this study, mortar bars were made with the as received cement chemistry and using additions of sulfate, and alkalis. The bars were then heat cured at various temperatures and stored in a saturated lime solution at room temperature. Measurements were made at predetermined time intervals. The series of mixes were made to determine the effect of varying sulfate levels, heat curing temperature, and alkali content in order to isolate the effect of these constituents. The cements were selected on the basis of tricalcium aluminate, alkali content, sulfate levels, C3S levels and fineness. The results indicate that a relationship exists between the rate and level of expansion experienced by the mortar bars and cementitious parameters, namely, alkali content, sulfate content, C3S levels and heat curing temperature.

Many engineering and scientific applications of flow in porous media are characterized by transport phenomena at multiple spatial scales, including pollutant transport, groundwater remediation, and acid injection to enhance well production. Carbon sequestration in particular is a multiscale problem, because the trapping and leakage mechanisms of CO2 in the subsurface occur from the sub-pore level to the basin scale. Quantitative and predictive pore-scale modeling has long shown to be a valuable tool for studying fluid-rock interactions in porous media. However, due to the size limitation of the pore-scale models (10-4-10-2m), it is impossible to model an entire reservoir at the pore scale. A straightforward multiscale approach would be to upscale macroscopic parameters (e.g. permeability) directly from pore-scale models and then input them into a continuum-scale simulator. However, it has been found that the large-scale models do not predict in many cases. One possible reason for the inaccuracies is oversimplified boundary conditions used in this direct upscaling approach. The hypothesis of this work is that pore-level flow and upscaled macroscopic parameters depends on surrounding flow behavior manifested in the form of boundary conditions. The detailed heterogeneity captured by the pore-scale models may be partially lost if oversimplified boundary conditions are employed in a direct upscaling approach. As a result, extracted macroscopic properties may be inaccurate. Coupling the model to surrounding media (using finite element mortars to ensure continuity between subdomains) would result in more realistic boundary conditions, and can thus improve the accuracy of the upscaled parameters. To test the hypothesis, mortar coupling is employed to couple pore-scale models and also couple pore-scale models to continuum models. Flow field derived from mortar coupling and direct upscaling are compared, preferably against a true solution if one exists. It is found in this dissertation that pore-scale flow and upscaled parameters can be significantly affected by the surrounding media. Therefore, using arbitrary boundary conditions such as constant pressure and no-flow boundaries may yield misleading results. Mortar coupling captures the detailed variation on the interface and imposes realistic boundary conditions, thus estimating more accurate upscaled values and flow fields. An advanced upscaling tool, a Super Permeability Tensor (SPT) is developed that contains pore-scale heterogeneity in greater detail than a conventional permeability tensor. Furthermore, a multiscale simulator is developed taking advantage of mortar coupling to substitute continuum grids directly with pore-scale models where needed. The findings from this dissertation can significantly benefit the understanding of fluid flow in porous media, and, in particular, CO2 storage in geological formations which requires accurate modeling across multiple scales. The fine-scale models are sensitive to the boundary conditions, and the large scale modeling of CO2 transport is sensitive to the CO2 behavior affected by the pore-scale heterogeneity. Using direct upscaling might cause significant errors in both the fine-scale and the large-scale model. The multiscale simulator developed in this dissertation could integrate modeling of CO2 physics at all relevant scales, which span the sub-pore or pore level to the basin scale, into one single simulator with effective and accurate communication between the scales. The multiscale simulator provides realistic boundary conditions for the fine scales, accurate upscaled information to continuum-scale, and allows for the distribution of computational power where needed, thus maintaining high accuracy with relatively low computational cost. / text