[pt] A caracterização do campo próximo em guias de onda ópticos torna-se indispensável quando se deseja confeccionar guias monomodo. Neste trabalho utilizou-se um sistema de medidas baseado na medida do campo próximo, para caracterizar guias de onda quanto ao seu conteúdo modal. Foram realizadas medidas do campo próximo de onda em GaAs/AlGaAs, com estruturas diferentes, para se verificar as suas características modais. Analisou-se, também, alguns parâmetros importantes nesta medida, como os alinhamentos e o ajuste do foco do sistema óptico. Baseado nos dados medidos, calculou-se o spot size dos guias nas direções horizontal e vertical, verificando-se a eficiência de acoplamento com fibras monomodo. Para se averiguar a precisão do sistema de medidas, uma fibra monomodo calibrada foi medida, verificando-se um erro de aproximadamente 1.5% nas medidas de spot size. / [en] Near field characterization of optical waveguides is extremely important in monomode waveguides production. This work has use a measurement system based on the near field measurement, for characterizing the modal contents of waveguides. In order to verify the modal characteristics of two GaAS/AlGaAs waveguides, with different structures, near fiels measurements were made. Important parameters, such as the alignment and the focal adjustment of the aoptical systems, were also analyzed. Using the results from the measurements, it was calculated the spot size of the waveguides in the horizontal and vertical directions, verifying the coupling efficiency with monomode fibers. A calibrated monomode fiber was measured to analyze the system precision. On using this measurement as a reference parameter a high precision was observed

This dissertation presents a case study which attempts to implement a passive Ultra High Frequency Radio Frequency Identification (UHF RFID) system on aircraft landing gear (LG) to permit component configuration management. It is shown that a monostatic RFID system with two reader antennas, one on the LG main fitting and one in the wing bay allows up to 64 kbits of data to be associated with each LG component. A 7 dB system margin allows data on each LG component to be updated wirelessly and will also enable a passive UHF RFID-based LG health and usage monitoring system when tags with required sensors become available. Results from an electromagnetic simulation show that when a metal is illuminated by a nearby antenna the E-field distribution close to its surface is stronger than in free space. To explore if the stronger E-field can be used to enhance the performance of a conventional passive tag, a 5 cm × 6 mm × 3.02 m aluminium bar has been selected as the tagging object and connected to the reader via an RF feed. It is shown that a conventional metal tag which has a maximum free space range of 1.3 m when mounted on a metal plate can be detected up to 30 m along the aluminium bar from the RF feed. When orientated with the long axis normal to the metal surface a conventional passive tag with a dipole antenna can efficiently harvest the E- field and can be read at least 50 m away from the antenna feed. The proposed use of metal objects as a nearfield antenna is well suited to some applications, but in others a significant wireless path is still required. In such a case, a semi-passive tag can be used. It is demonstrated that a semi-passive tag only requires 14.4 ̧œ‡̧‘Š to be read over 42 m in a bistatic RFID system. Such a power consumption can be easily achieved by most energy harvesting techniques. It is demonstrated that a solar-powered semi-passive tag can be read at a range of 22 m, but its performance is still limited by multipath effects. A distributed antenna system (DAS) can be used to overcome these effects by using frequency and phase hopping techniques. It is demonstrated that 50 solar-powered semi-passive tags can be read with no missed detections over a 10 m × 20 m office area with 4 dB system margin.

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M.Ing. (Electrical And Electronic Engineering) / Patient safety in healthcare is sometimes compromised due to medical and clerical errors. These errors can increase the operational cost of healthcare if not identified and rectified speedily. They can also result in misdiagnosis, wrong treatment options being provided to patients and in the worst case may result in fatalities. Healthcare errors in medication documentation, administration, and prescription can cause incorrect medicine administration and dosage instructions for patients. Sub-Saharan Africa has the lowest percentage (adults is 59% and youth is 70%) of literacy compared to other regions of the world sitting at (adults is 84% and youth is 89%). The challenge facing illiterate patients is that they can easily make the same mistakes and may not take their medication correctly. The application of Near Field Communication (NFC) technology in healthcare has demonstrated some advantages of security, accuracy and effectiveness over other technologies. The availability of NFC in some smartphones has also encouraged the development of more applications. The main objective of this thesis is to present a solution using an Android based NFC application that enables a NFC enabled smartphone to read NFC tags placed on medication containers and be able to play the audio instructions to illiterate patients. Based on a comprehensive review of the literature on NFC applications in healthcare, this solution is the first of its kind. A set of experiments were done in an effort to understand the operation of NFC phones under different environments. The proposed application reads the NFC tag placed on the medicine container. The data read from the NFC tag is used to identify the audio file corresponding to the particular patient’s medicine instructions. If the audio instructions are not available, on the phone, it is fetched from a remote server database using an Internet connection. The application automatically plays the audio file to the patient. Three research hypotheses were tested and it was confirmed that (H1), modified NFC antenna can reduce the level of induced power in it; (H2), the NFC technology is faster and more accurate in reading tag code that Barcode technology reading the barcode; (H3), the NFC reading process of NFC tag code is not negatively affected by the amount of light in the environment it is operated in. The Barcode reading accuracy was 10% errors when operating in the environment with light brightness of 128000 lumens. When the light brightness was reduced to 8900 lumens, the Barcode accuracy errors increased to 45%.

Near-field magnetic induction (NFMI) is a short range wireless technology that uses loop antennas coupled by a magnetic field. NFMI antennas are electrically small and thus extremely inefficient and narrow band, making system design for multi-user and high-bitrate applications challenging. The goals of this thesis are to develop a test platform suitable for NFMI antenna testing, to model, design and test NFMI antennas that have high bandwidth-efficiency, and to explore the possibility of using MIMO (multiple-input multiple-output) to increase the capacity of the NFMI channel. This thesis provides system implementations, test results, and channel modeling to aid in the design of future NFMI systems. Implementation of a multi-channel discrete-time wireless system are provided for PC-based software and FPGA-based firmware as a platform for antenna testing. Optimized antenna designs in terms of efficiency and bandwidth are presented, achieving the theoretical bandwidth-efficiency bound for small antennas. Preliminary modeling and simulation results for the NFMI-MIMO channel are included, which show that the information-theoretic capacity of the NFMI-MIMO channel is approximately double the standard single-antenna NFMI capacity at 10 bits/s/Hz.

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Th is paper focuses on bridging the gap between the physical and digital world by creating a balance between performative (learned) interaction and transparent (direct-realism) interaction. The balance between these two types of interactions is also reminiscent of the balance between how people currently interact with digital objects and how people interact with physical objects.This paper does a deep review of the many ways designers, researchers, and even psychologists have studied interaction between the physical and digital world. The project started off with a literature review, the literature review consisted of four sections; a review of related papers and projects, discussion of related theories, my analysis of reviewed literature, and ended with the creation of design guidelines for Near-Field Communication (NFC) devices.The paper proceeds through a hands-on, iterative physical prototyping process in order to develop aprototype that allows our physical interactions to be supported digitally through the use of mobile computing. Wireless communication and metadata are used to create a physical interaction, which is both highly personalized and contextually based in a digital way. An interaction that supports our deeper understanding of the purpose of the interaction, and which also benefi ts from the availability of digital information, which is personal and contextual.Lastly a proposal for a fi nal design for a digital device that will allow the user to bridge the gap between the physical and digital world is described in this paper. This final design incorporates both my analysis of the reviewed projects, theories and literature, and the findings from two rounds of user testing with and iterative physical prototype. This is followed by overall conclusions and suggestions for future work.

A lack of complex analysis for a thermally buoyant jet in a stratified crossflow has motivated the studies presented. A computational approach using the incompressible Navier--Stokes equations (NSE) under the Boussinesq approximation is utilized. Temperature and salinity scalar transport equations are utilized in conjunction with a linear equation of state (EOS) to obtain the density field and thus the buoyancy forcing. Comparing simulation data to experimental data of a point heat source in a stratified environment provides general agreement between the aforementioned computational model and the physics studied. From the literature surveyed, no unified agreement was presented on the selection of turbulence models for the jet--in--crossflow (JICF) problem. For this reason, a comparison is presented for a standard Reynolds--Averaged Navier--Stokes (RANS) and a hybrid Reynolds--Averaged Navier--Stokes/large eddy simulation (HRLES) turbulence model. The mathematical differences are outlined as well as the implications each model has on solving a buoyant jet in stratified crossflow. The RANS model provides a general over prediction of all flow quantities when comparing to the HRLES models. Studies involving the removal of the thermal component inside the jet as well as varying the environmental stratification strength have largely determined that these affects do not alter the near-field in any significant way, at least for a high Reynolds number JICF. The velocity ratio of the jet being the ratio of the jet velocity to the free--stream flow velocity. Deviating from a velocity ratio of one has provided information on the variability of the forcing on the plate the jet exits from, as well as in the integrated energy quantities far downstream of the jet's exit. The departures presented here show that any deviation from the unity value provides an increase in the overall forces seen by the plate. It was also found that the change in the integrated potential and turbulent kinetic energies is proportional to the deviation from a unity velocity ratio. / Master of Science / A lack of complex analysis for a heated jet in a non-uniform crossflow has motivated the studies presented. A computational approach for the fluid dynamics governing equations under specific assumptions is implemented. Additional equations are solved for temperature and salinity in conjunction with a linear equation of state to obtain the density field. Comparing simulations to experimental data of a point heat source in a non-uniform, fluid tank provides general agreement between the aforementioned computational model and the physics studied. Studying the literature yields no unified agreement on the selection of turbulence treatment for the jet-in-crossflow problem. For this reason, a comparison is presented for two various techniques with differing complexity. The mathematical differences as well as the implications each model are outlined, specifically pertaining to a heated jet in a non-uniform crossflow. The simpler model provides a general over prediction when compared to the more complex model. Studies involving the removal of the heat from inside the jet as well as varying the environmental forcing have largely determined that these affects do not alter the flow field near the jet's origin point in any significant way. Changing the jet's velocity has provided information on the variability of the forcing on the plate the jet exits from, as well as in the energy released into the environment far downstream of the jet's exit. The ratios presented show that any deviation from a notional value provides an increase in the overall forces seen by the plate. It was also found that the change in the released energies is proportional to the deviation from the notional jet velocity.