Submitted by Mario BC (mario@bc.ufrpe.br) on 2018-07-23T14:50:16Z No. of bitstreams: 1 Nathalia Barbosa da Silva.pdf: 2192959 bytes, checksum: b37dabac91b4ee92a2aed0b0c84c84ab (MD5) / Made available in DSpace on 2018-07-23T14:50:16Z (GMT). No. of bitstreams: 1 Nathalia Barbosa da Silva.pdf: 2192959 bytes, checksum: b37dabac91b4ee92a2aed0b0c84c84ab (MD5) Previous issue date: 2017-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The grape cv. Sweet Sapphire® is a new hybrid variety which has as its main characteristics the black color, seedless and a larger shape than the common grape, is described as elongated tubular with a dimpled end. This new variety, cultivated in the city of Petrolina-PE, was submitted to the connective drying to obtain raisins, and this study had as objective to evaluate the potential of grape cv. Sweet Sapphire® for the production of raisins, to define the influence of drying temperature and chemical immersion pretreatment (K2CO3 and extra virgin olive oil solutions) on the final quality of the raisins, as well as determining the effects of the convective drying on the physicochemical characteristics, the content of phenolic compounds, antioxidant properties and sensorial evaluation of the obtained product. In order to define the optimal drying conditions, factorial design 24-1 was applied, having as independent variables the concentration of K2CO3 (2 to 6%), concentration of extra virgin olive oil (0.5 to 2.5%), time immersion (0.5 to 5 min) and drying temperature (45 to 60). The drying temperature was the variable that influenced significantly the moisture, water activity, soluble solids and weight of the samples, while the immersion time influenced the phenolic content. In this way, the optimal drying condition for obtaining raisins cv. Sweet Sapphire® was a temperature of 55°C, immersion time of 2.5 minutes, concentration of K2CO3 of 2% and of extra virgin olive oil of 0.5%, showing significant efficiency in reducing the total drying time. The grapes in nature and raisins were submitted to chemical composition and physico-chemical analyzes and the difference between the evaluated parameters was significant, with concentration in the content of compounds due to loss of moisture. The raisin presented low firmness; high content of phenolic compounds and total anthocyanins and, consequently, exhibited antioxidant potential, since it demonstrated efficiency in the capture of the radicals DPPH● and ABTS+• and ferric reduction (FRAP). The obtained raisins presented satisfactory sensorial quality (percentage of acceptability greater than 70%) and suitable intention of purchase by the consumers, being able to be considered a food with functional characteristics, with potential for the diversification of the commercial production, making it possible to obtain of a new competitive product on the commerce. / A uva cv. Sweet Sapphire® é uma nova variedade de uva híbrida que possui como características principais a cor negra, sem sementes e um formato maior que a uva comum, descrito como tubular alongada com uma extremidade convinde. Esta nova variedade, cultivada no município de Petrolina-PE, foi submetida à secagem conectiva para obtenção de uva-passa, e este estudo teve como objetivo avaliar o potencial da uva cv. Sweet Sapphire® para a produção de uva-passa, verificando a influência da temperatura de secagem e do pré-tratamento químico de imersão (soluções de K2CO3 e azeite de oliva extra virgem) na qualidade final das uvas-passas, bem como determinar os efeitos da secagem convectiva sobre as características físico-químicas, o teor de compostos fenólicos, propriedade antioxidante e qualidade sensorial do produto obtido. Para definir as melhores condições de secagem foi aplicado o planejamento fatorial 24-1 tendo como variáveis independentes: a concentração de K2CO3 (2 a 6% p/v), concentração de azeite de oliva extra virgem (0,5 a 2,5% v/v), tempo de imersão (0,5 a 5 min) e temperatura de secagem (45 a 60ºC). A temperatura de secagem foi a variável que influenciou significativamente na umidade, atividade de água, sólidos solúveis e peso das amostras, enquanto que o tempo de imersão influenciou no teor de fenólicos. Desta forma, a melhor condição de secagem para obtenção da uva-passa cv. Sweet Sapphire® foi temperatura de 55°C, tempo de imersão de 2,5 minutos, concentração de K2CO3 de 2% e de azeite de oliva extra virgem de 0,5%, mostrando eficiência significativa na redução do tempo total de secagem. As uvas in natura e as uvas-passas foram submetidas às análises de composição química e físico-química e a diferença entre os parâmetros avaliados foi significativa, ocorrendo concentração no conteúdo de compostos devido a perda de umidade. A uva-passa apresentou baixa firmeza; elevado teor de compostos fenólicos e antocianinas totais e consequentemente, exibiu potencial antioxidante, uma vez que demonstrou eficiência na captura dos radicais DPPH● e do ABTS+• e na redução de ferro (FRAP). A uva-passa obtida apresentou qualidade sensorial satisfatória (percentual de aceitabilidade maior que 70%) e boa intenção de compra por parte dos consumidores, podendo ser considerada um alimento com características funcionais, com potencial para a diversificação da produção comercial, tornando possível a obtenção de um novo produto competitivo no mercado.

Current design models, approaches and theories are highly fragmented, have seldom been compared with one another, and rarely attempted to be consolidated. Novelty is a measure of creativity of engineering products and positively influences product success. Using physical laws and effects for designing can improve the chances of creativity but they cannot be used directly owing to their inadequate current representations. It is important to address activities, outcomes, requirements and solutions in designing. Conceptual design is an early phase in engineering design and needs to be supported better. A systematic approach for designing often increases effectiveness and efficiency. Thus, the broad objective of this thesis is to develop and validate a comprehensive understanding of how designing occurs during the conceptual phase of engineering design, and to support variety and novelty of designs during this phase. The approach followed is: (a) formulate and validate an understanding of novelty and its relationships to the designing constructs, in current designing, and(b)develop and validate a support, founded on the current designing, to improve novelty. The understanding and the support are addressed, respectively, through an integrated model and a systematic framework for designing; the model and the framework comprise activities, outcomes(including laws and effects), requirements and solutions. An integrated model of designing, GEMS of SAPPhIRE as req-sol is developed by combining activities(Generate, Evaluate, Modify, Select– GEMS), outcomes (State change, Action, Parts, Phenomenon, Input, oRgans, Effect–SAPPhIRE), requirements (req) and solutions (sol), identified from a comprehensive survey of existing design models and approaches. Validation of SAPPhIRE model with existing systems indicates that the model can be used to describe analysis and synthesis, both of which together constitute designing. Validation of the integrated model using existing videos of design sessions, to check if all its constructs are naturally used in designing, reveals that:(a) all the constructs are naturally used;(b) not all the outcomes are explored with equal intensity;(c) while high numbers of action and parts are observed, only low numbers of phenomenon, effects and organs are found. Empirical study using another set of design sessions to study the relationships between novelty and the outcomes reveals that novelty of a concept space depends on the variety of the concept space, which in turn depends on the variety of the idea space explored. Novelty and variety of a concept space also depend on the number of outcomes explored at each abstraction level. Thus, phenomena and effects are also vital for variety and novelty. Based on the above, GEMS of SAPPhIRE as req-sol framework for designing is proposed. The framework is divided into: Requirements Exploration Stage(RES) and Solutions Exploration Stage(SES). In RES and SES, requirements and solutions respectively at all the abstraction levels including SAPPhIRE are generated, evaluated, modified and selected. The framework supports task clarification, conceptual and early embodiment phases of designing, and provides process knowledge. Comparison of the framework against existing design models, theories and approaches reveals that:(a) not all existing models, theories and approaches address activities, outcomes, requirements and solutions together;(b) those that address all these constructs together do not make a distinction between requirements and solutions; and(c) no model or approach explicitly addresses novelty. The usability of the framework and Idea-inspire is assessed by applying them in an industrial project for designing novel concepts of lunar vehicle mobility system. The use of this combined support enables identification of critical requirements, development of a large variety of ideas and concepts. One of these concepts is physically and virtually modelled, and tested, and is found to satisfy all the requirements. A catalogue of physical laws and effects is developed using SAPPhIRE model to provide assistance to designers, especially for phenomena, effects and organs. Observations found during this development are reported. A comparative validation of the framework and the catalogue for their support to design for variety and novelty is done using comparative observational studies. Results from the observational studies reveal that the variety and the novelty of concept space improve with the use of the framework, or with the frame work and the catalogue, as compared to variety and novelty with no support.

No abstract available. / Thesis (PhD)--University of Pretoria, 2010. / Physics / unrestricted

Experimental evidence is presented that supports the theory that beats between transverse modes are responsible for the fast modulation carried on occasions by laser relaxation oscillations. / Thesis / Master of Engineering (ME)

No description available.

No description available.

As specialized materials are developed for various applications, it becomes desirable to test them under adverse conditions, such as at elevated temperatures and in harsh environments. It is increasingly important that sensors be developed to meet the growing needs of research and industry. The ability of sapphire to withstand elevated temperatures and many chemically harsh environments has long been recognized. However, currently available sapphire fiber possesses poor optical quality and is not available with a cladding. It has found use in a variety of temperature sensors, but the investigation of sapphire-based strain and displacement sensors has been limited. The primary development of a white-light Michelson interferometer that utilizes a sapphire fiber sensing head is presented in this thesis. Development includes efforts to combat the poor optical quality of the sapphire fiber, minimize polarization mode fading, and preferentially excite the fundamental mode of the sapphire fiber. This thesis demonstrates the feasibility of fabricating a Michelson white-light interferometer capable of measuring displacements in environments ranging from room temperature to 800 degrees Celsius. The sensor developed in this work is capable of measuring displacements exceeding 6.4 millimeters at room temperature, and exceeding 1 millimeter at 800 degrees Celsius. This thesis also presents the application of this sensor to the alignment of a sapphire-fiber based Fabry-Perot sensor. This technique allows the Fabry-Perot sensor to be aligned so that usable fringes are always obtained. Alignment of the sapphire-fiber based Fabry-Perot sensors has been considered prohibitively difficult. / Master of Science

This dissertation focuses on developing new technologies for ultra-low-cost sapphire fiber-optic high-temperature sensors. The research is divided into three major parts, the souceless sensor, the simple Fabry-Perot (F-P) interrogator, and the sensor system. Chapter 1 briefly reviews the background of thermal radiation, fiber optic F-P sensors, and F-P signal demodulation. The research goal is highlighted. In Chapter 2, a temperature sensing system is introduced. The environmental thermal radiation was used as the broadband light source. A sapphire wafer F-P temperature sensor head was fabricated, with an alumina cap designed to generate a stable thermal radiation field. The radiation-induced optical interference pattern was observed. We demodulated the temperature sensor by white-light-interferometry (WLI). Temperature resolution better than 1°C was achieved. Chapter 3 discusses a novel approach to demodulate an optical F-P cavity at low-cost. A simple interrogator is demonstrated, which is based on the scanning-white-light-interferometry (S-WLI). The interrogator includes a piece of fused silica wafer, and a linear CCD array, to transform the F-P demodulation from the optical frequency domain to the spatial domain. By using the light divergence of an optical fiber, we projected a tunable reference F-P cavity onto an intensity distribution along a CCD array. A model for S-WLI demodulation was established. Performance of the new S-WLI interrogator was investigated. We got a good resolution similar to the well-known traditional WLI. At last, we were able to combine the above two technologies to a sapphire-wafer-based temperature sensor. The simple silica wafer F-P interrogator was optimized by focusing light to the image sensor. This approach improves the signal to noise ratio, hence allows the new integrator to work with the relatively weak thermal radiation field. We, therefore, proved in the experiment, the feasibility of the low-cost sourceless optical Fabry-Perot temperature sensor with a simple demodulation system. / PHD / Temperature measurements for high temperature harsh environments is a challenge industrial task. In this work, a low-cost sapphire fiber high temperature sensor is introduced which uses single crystal sapphire fiber as the light guiding and a sapphire-wafer-based Fabry-Perot (F-P) interferometer as the temperature sensing element. The research goal is to provide an optical sensing system whose price is competitive to the high temperature thermocouples. Two technologies were developed to reduce the cost of the sensing system, the sourceless sensor head design and the low-cost wafer-based F-P interrogator. The sourceless sensor head makes use of the environmental thermal radiation as a broadband light source, together with the white light interferometry signal demodulation method, for temperature measurements. In this case, the system avoids using not only an external light, but also the light driver and the light coupling element. A low-cost F-P cavity interrogation method was introduced to demodulate the sapphire-wafer-based temperature sensing F-P cavity. The signal demodulation is based on the scanning white light interferometry, but a reliable and low-cost reference F-P cavity is introduced. It includes only a piece of transparent wafer and a CCD array to transfer the interference fringe from the spectra domain to the spatial domain and therefore a low cost CCD can be directly applied to identify the optical path distance of the sensing OPD. Eventually, the above two technologies were able to put together and an extremely low-cost F-P temperature sensing system was built. It has a good potential for further applications and commercialization.

Optical fiber sensors are widely applied in modern sensing systems. Taking advantage of the high sensitivity of optical interference, optical coherence fiber sensors, such as fiber Bragg gratings (FBGs) and Fabry-Perot interferometers (FPIs), have been investigated intensively and utilized broadly in optical sensing systems. Multimode fibers (MMFs) offer low coupling loss, high compatibility with various light sources, and insensitivity to ambient fluctuations, which are preferred for reliable and low-cost sensing systems. Therefore, the combination of optical coherence sensors and MMFs have facilitated and will continue to contribute to various optical sensor designs with desirable performances. This dissertation addresses the design and construction of optical coherence sensors in multimode fibers and presents several fully multimode fiber sensing systems with low coherence light source. Moreover, a theoretical analysis of fiber mode excitations, model coupling, and multimodal interference is conducted, and a numerical model is constructed to study the behaviors of optical coherence sensors in MMFs. With the femtosecond laser point-by-point inscription method, parallel fiber Bragg gratings (pFBGs), scattering array interferometers (SAIs), and densely multiplexable scattering array interferometers (DMSAIs) in sapphire fibers are proposed, fabricated and characterized, achieving excellent performance in multiplexed high temperature sensing. The study on SAI signals also revealed the unique coherence properties of MMFs. This work points out that the coherence properties in MMFs play a significant role in affecting the performances of optical coherence sensors, and such properties are closely related to both geometrical and optical properties of the fibers. This work also presents both theoretical and experimental tools to explore such properties and predict and test the performance of optical coherence sensors in MMFs, which is of great significance in the applications of such sensors in the real world. / Doctor of Philosophy / Optical fibers have been considered a powerful media that opened a new era in the field of telecommunication and optical sensing. Owing to their excellent resistance to chemical corrosion, immunity to electromagnetic interference, extremely low loss transmission at long distance, small size, and large aspect ratio, optical fibers are considered an ideal media to construct optical sensors. Optical coherence sensors are a very important type of optical fiber sensors that utilize the optical coherence property, such as interference, for sensing purposes. A lot of such sensors are generally constructed with single mode fibers (SMFs) owing to the high-quality coherence interaction supported by the fundamental-mode-only operation. Multimode fibers (MMFs), however, process high compatibility with various light sources owing to the high power-coupling efficiency because of large core size, which is desirable for industrial applications that requires low-cost and robust sensing systems. Meanwhile, the high modal volume of MMFs causes severe challenges on the design and fabrication of optical coherence sensors in MMFs. In this work, theoretical analysis of the mode excitation and coupling in MMFs is discussed, and a numerical model to simulate the behaviors of optical coherence sensors in MMFs is built. Then, using femtosecond laser point-by-point fabrication technique, parallel fiber Bragg gratings (pFBGs), scattering array interferometers (SAIs), and densely multiplexable scattering array interferometers (DMSAIs) are demonstrated and proven to be effective in multiplexable temperature sensing. Furthermore, using the numerical model and the SAI structures, coherence properties in MMFs are studied. This research may facilitate a deeper understanding of coherence properties in optical waveguides and support the design of novel fiber sensors that can be utilized in the real world.

In this thesis, we report the development of two types of optical sensors, one for high temperature pressure measurements and the other for real-time particle detection. With a high melting temperature (over 2000°C), low optical loss, and excellent corrosion resistance, sapphire (α-Al₂O₃) is ideal for high temperature sensing applications. Fabry-Perot (FP) cavity with optical interrogation of pressure response. The prototype is based on an extrinsic FP interferometer design and is constructed by combining reactive ion etching (RIE) with direct wafer bonding. Long-term testing proves that the adhesive-free wafer bond is sufficient to create a sealed Fabry-Perot cavity as a pressure transducer. Pressure measurement over a range of 6 to 200 psi has been demonstrated at room temperature using white-light interferometry. For the other sensor, the goal is to detect the presence of micro- and nanoparticles in real time. The sensor is based on a silica fiber taper, and we aim to detect particle presence by measuring optical scattering and absorption induced by particles attached to the taper surface. To establish the relationship between particle density and optical transmission loss, we first consider a model where Au nanospheres are self-assembled on taper surface through electrostatic interaction. An analytical model is established to describe the adsorption of gold nanospheres onto cylindrical and spherical silica surfaces from quiescent aqueous particle suspensions. The curved surfaces of the fiber taper and microspheres are coated with nm-thick layer of a polycation, enabling irreversible adsorption of the negatively charged spheres. Our results fit well with theory, which predicts that the rates of particle adsorption will depend strongly on the surface geometry. In particular, adsorption is significantly faster on curved than on planar surfaces at times long enough that the particle diffusion length is large compared to the surface curvature. This is of particular importance for plasmonic sensors and other devices where particles are deposited from a suspension onto surfaces which may have non-trivial geometries. We have established a theoretical model that can describe optical loss generated by particles on taper surface. This theory is validated by measuring, in real time, optical loss during the self-assembly of gold nanoparticles. We find that the measured optical loss can be quantitatively explained by the presence of multiple guided modes within the fiber taper region. Based on this work, we incorporate a fiber taper into a cascade impactor and show that welding aerosols attached to the fiber taper surface can induce measurable transmission loss during the welding process. / Ph. D.