Non-visual overviews of complex data sets

This paper describes the design and preliminary testing of an interface to obtain overview information from complex numerical data tables non-visually, which is something that cannot be done with currently available accessibility tools for the blind and visually impaired users. A sonification technique that hides detail in the data and highlights its main features without doing any computations to the data, is combined with a graphics tablet for focus+context interactive navigation, in an interface called TableVis. Results from its evaluation suggest that this technique can deliver better scores than speech in time to answer overview questions, correctness of the answers and subjective workload

The eleven antenna: a compact low-profile decade bandwidth dual polarized feed for reflector antennas

A novel dual polarized ultrawide-band (UWB) feed with a decade bandwidth is presented for use in both single and dual reflector antennas. The feed has nearly constant beam width and 11 dBi directivity over at least a decade bandwidth. The feed gives an aperture efficiency of the reflector of 66% or better over a decade bandwidth when the subtended angle toward the sub or main reflector is about 53°, and an overall efficiency better than 47% including mismatch. The return loss is better than 5 dB over a decade bandwidth. The calculated results have been verified with measurements on a linearly polarized lab model. The feed has no balun as it is intended to be integrated with an active 180° balun and receiver. The feed is referred to as the Eleven antenna because its basic configuration is two parallel dipoles 0.5 wavelengths apart and because it can be used over more than a decade bandwidth with 11 dBi directivity. We also believe that 11 dB return loss is achievable in the near future

Developing an interactive overview for non-visual exploration of tabular numerical information

This thesis investigates the problem of obtaining overview information from complex tabular numerical data sets non-visually. Blind and visually impaired people need to access and analyse numerical data, both in education and in professional occupations. Obtaining an overview is a necessary first step in data analysis, for which current non-visual data accessibility methods offer little support. This thesis describes a new interactive parametric sonification technique called High-Density Sonification (HDS), which facilitates the process of extracting overview information from the data easily and efficiently by rendering multiple data points as single auditory events. Beyond obtaining an overview of the data, experimental studies showed that the capabilities of human auditory perception and cognition to extract meaning from HDS representations could be used to reliably estimate relative arithmetic mean values within large tabular data sets. Following a user-centred design methodology, HDS was implemented as the primary form of overview information display in a multimodal interface called TableVis. This interface supports the active process of interactive data exploration non-visually, making use of proprioception to maintain contextual information during exploration (non-visual focus+context), vibrotactile data annotations (EMA-Tactons) that can be used as external memory aids to prevent high mental workload levels, and speech synthesis to access detailed information on demand. A series of empirical studies was conducted to quantify the performance attained in the exploration of tabular data sets for overview information using TableVis. This was done by comparing HDS with the main current non-visual accessibility technique (speech synthesis), and by quantifying the effect of different sizes of data sets on user performance, which showed that HDS resulted in better performance than speech, and that this performance was not heavily dependent on the size of the data set. In addition, levels of subjective workload during exploration tasks using TableVis were investigated, resulting in the proposal of EMA-Tactons, vibrotactile annotations that the user can add to the data in order to prevent working memory saturation in the most demanding data exploration scenarios. An experimental evaluation found that EMA-Tactons significantly reduced mental workload in data exploration tasks. Thus, the work described in this thesis provides a basis for the interactive non-visual exploration of a broad range of sizes of numerical data tables by offering techniques to extract overview information quickly, performing perceptual estimations of data descriptors (relative arithmetic mean) and managing demands on mental workload through vibrotactile data annotations, while seamlessly linking with explorations at different levels of detail and preserving spatial data representation metaphors to support collaboration with sighted users

La fatiga en las barras de acero corrugado para refuerzo de hormigón

Para conseguir aprovechar los recursos que la sociedad invierte en infraestructuras de manera óptima es imprescindible, para la ingeniería civil, un buen conocimiento de los materiales y de sus propiedades. Partiendo de esta premisa, el objetivo de esta tesina es aportar conocimiento a la caracterización de las barras de acero corrugado para refuerzo de hormigón en su funcionamiento frente a la fatiga. Definimos fatiga como la alteración mecánica de los materiales bajo el efecto de solicitaciones repetidas. En la Ingeniería Civil, la fatiga afecta a estructuras sometidas a elevados ciclos de carga y descarga, especialmente a estructuras de transportes de masas y a aquellas sometidas a la acción del oleaje y el viento. La respuesta de los materiales a fatiga se caracteriza experimentalmente por el número de ciclos que resisten a la rotura (N) ante una acción cíclica de amplitud constante (S). Ensayando para diversos valores de la acción se traza la llamada curva S-N, que representa el comportamiento del material. La respuesta a fatiga del hormigón armado depende tanto de la respuesta del hormigón como del acero. De cara a asegurar la durabilidad del mismo a fatiga, es importante cuidar los detalles constructivos, pues el efecto de la fatiga aumenta ante la presencia de otros fenómenos de degradación, como fisuración y oxidación de armaduras

The Random Line-of-Sight Over-the-Air Measurement System

As our society becomes increasingly connected, a growing number of devices rely on wireless connectivity. The type, use and form factor of these devices range from wearables to entire vehicles. Additionally, the fifth generation of wireless communication (5G) introduces new communication bands, also at higher frequencies. At these millimeter-wave frequencies, large portions of bandwidth are available which are needed in order to increase the data rates.In this scenario, testing and verifying the wireless communication performance has an increasingly important role. In modern devices, testing needs to be performed over-the-air (OTA), as direct conducted measurements to the antenna ports become unfeasible. Moreover, there is still ongoing research to understand how testing should be performed for devices with large form-factors, such as vehicles, as well as for higher frequencies. The proposed methods are mainly based on techniques for mobile phone testing at the current communication bands, i.e., sub-6 GHz. However, scaling and adapting these methods to work for future needs presents challenges. A possible solution to meet the future testing requirements is offered by the following hypothesis: "If a wireless device is tested with good performance in both pure-LOS and RIMP environments, it will also perform well in real-life environments and situations, in a statistical sense". The rich isotropic multipath (RIMP) and the random line-of-sight (random-LOS) are therefore identified as the two representative edge environments for testing. This thesis focuses on the random-LOS environment, and its practical realization to test the wireless performance of different devices. The thesis is divided into three main parts. The first part describes the practical realization of random-LOS OTA measurement setups. Three different setups are presented, a virtual planar array and two reflector antennas. One reflector system is aimed at vehicular testing for frequencies below 6 GHz, while the other targets smaller devices at 28 GHz. The second part of the thesis focuses on numerical and experimental verification of the random-LOS measurement setups. In the verification, numerical simulations and measurements of the test zone variations are compared for the proposed OTA measurement systems.The third and last part focuses on how passive and active measurements can be performed using a random-LOS measurement setup. The measurements demonstrate the application of the designed OTA measurement systems for passive antenna measurements, as well as active 2x2 multiple-input multiple-output (MIMO) measurements on a complete vehicle

Study of Grating Efficiency of Planar Arrays

This paper studies the aperture efficiency reduction due to grating lobes of a uniformly excited planar array. The grating lobes will not cause major interference problems in the millimeter wave region, because of the attenuation in the atmosphere, but they cause a reduction of the directivity and thereby aperture efficiency of the antenna. Therefore, we present a simple formula for calculating the aperture efficiency in the presence of grating lobes, from knowledge of the element pattern. The accuracy of the formula is verified by comparing with simulated results for a full array with slot elements

Design and experimental verification of ridge gap waveguide in bed of nails for parallel-plate mode suppression

This study describes the design and experimental verification of the ridge gap waveguide, appearing in the gap between parallel metal plates. One of the plates has a texture in the form of a wave-guiding metal ridge surrounded by metal posts. The latter posts, referred to as a pin surface or bed of nails, are designed to give a stopband for the normal parallel-plate modes between 10 and 23 GHz. The hardware demonstrator includes two 90° bends and two capacitive coupled coaxial transitions enabling measurements with a vector network analyser (VNA). The measured results verify the large bandwidth and low losses of the quasi-transverse electromagnetic (TEM) mode propagating along the guiding ridge, and that 90° bends can be designed in the same way as for microstrip lines. The demonstrator is designed for use around 15 GHz. Still, the ridge gap waveguide is more advantageous for frequencies above 30 GHz, because it can be realised entirely from metal using milling or moulding, and there are no requirements for conducting joints between the two plates that otherwise is a problem when realising conventional hollow waveguides. © 2011 The Institution of Engineering and Technology.Kildal, P.; Zaman, AU.; Rajo Iglesias, E.; Alfonso Alós, E.; Valero-Nogueira, A. (2011). Design and experimental verification of ridge gap waveguide in bed of nails for parallel-plate mode suppression. IET Microwaves Antennas and Propagation. 5(3):262-270. doi:10.1049/iet-map.2010.0089S26227053Kildal, P.-S., Alfonso, E., Valero-Nogueira, A., & Rajo-Iglesias, E. (2009). Local Metamaterial-Based Waveguides in Gaps Between Parallel Metal Plates. IEEE Antennas and Wireless Propagation Letters, 8, 84-87. doi:10.1109/lawp.2008.2011147Kildal, P.-S.: ‘Waveguides and transmission lines in gaps between parallel conducting surfaces’, (European Patent Application EP08159791.6)7 July 2008Rajo-Iglesias, E., Zaman, A. U., & Kildal, P.-S. (2010). Parallel Plate Cavity Mode Suppression in Microstrip Circuit Packages Using a Lid of Nails. IEEE Microwave and Wireless Components Letters, 20(1), 31-33. doi:10.1109/lmwc.2009.2035960Kildal, P.-S. (1990). Artificially soft and hard surfaces in electromagnetics. IEEE Transactions on Antennas and Propagation, 38(10), 1537-1544. doi:10.1109/8.59765Valero-Nogueira, A., Alfonso, E., Herranz, J. I., & Kildal, P.-S. (2009). Experimental Demonstration of Local Quasi-TEM Gap Modes in Single-Hard-Wall Waveguides. IEEE Microwave and Wireless Components Letters, 19(9), 536-538. doi:10.1109/lmwc.2009.2027051Lier, E. (1990). Analysis of soft and hard strip-loaded horns using a circular cylindrical model. 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Microwave and Optical Technology Letters, 49(8), 1875-1877. doi:10.1002/mop.22586Šipuš, Z., Merkel, H., & Kildal, P.-S. (1997). Green’s functions for planar soft and hard surfaces derived by asymptotic boundary conditions. IEE Proceedings - Microwaves, Antennas and Propagation, 144(5), 321. doi:10.1049/ip-map:19971335CST Microwave Studio 2008. Available at: www.cst.comKehn, M. N. M., & Kildal, P.-S. (2005). Miniaturized rectangular hard waveguides for use in multifrequency phased arrays. IEEE Transactions on Antennas and Propagation, 53(1), 100-109. doi:10.1109/tap.2004.840519Malcolm Ng Mou Kehn, M. N. M., Nannetti, Cucini, Maci, & Kildal. (2006). Analysis of dispersion in dipole-FSS loaded hard rectangular waveguide. IEEE Transactions on Antennas and Propagation, 54(12), 2275-2282. doi:10.1109/tap.2006.879198Grbic, A., & Eleftheriades, G. V. (2003). Periodic analysis of a 2-D negative refractive index transmission line structure. IEEE Transactions on Antennas and Propagation, 51(10), 2604-2611. doi:10.1109/tap.2003.817543Eleftheriades, G.V., and Balmain, K.G.: ‘Metamaterials for controlling and guiding electromagnetic radiation’, (US Patent 6859114 – Filed 2 June 2003)McKinzie, W.F.: ‘Circuit and method for suppression of electromagnetic coupling and switching noise in multilayer printed circuit boards’, (US Patent No. 7,215,007 B2)Schellenberg, J. M. (1995). CAD models for suspended and inverted microstrip. IEEE Transactions on Microwave Theory and Techniques, 43(6), 1247-1252. doi:10.1109/22.390179Anderson, T. N. (1956). Rectangular and Ridge Waveguide. IEEE Transactions on Microwave Theory and Techniques, 4(4), 201-209. doi:10.1109/tmtt.1956.1125063Pozar, D.: ‘Microwave engineering’, 3rd(Wiley 2005), p. 139Bosiljevac, M., Sipus, Z., & Kildal, P.-S. (2010). Construction of Green’s functions of parallel plates with periodic texture with application to gap waveguides – a plane-wave spectral-domain approach. IET Microwaves, Antennas & Propagation, 4(11), 1799. doi:10.1049/iet-map.2009.0399Zaman, A. U., Rajo-Iglesias, E., Alfonso, E., & Kildal, P.-S. (2009). Design of transition from coaxial line to ridge gap waveguide. 2009 IEEE Antennas and Propagation Society International Symposium. doi:10.1109/aps.2009.5172186Sharp, E. D. (1963). A High-Power Wide-Band Waffle-Iron Filter. IEEE Transactions on Microwave Theory and Techniques, 11(2), 111-116. doi:10.1109/tmtt.1963.1125611KIRINO, H., OGAWA, K., & OHNO, T. (2008). A Variable Phase Shifter Using a Movable Waffle Iron Metal Plate and Its Applications to Phased Array Antennas. IEICE Transactions on Communications, E91-B(6), 1773-1782. doi:10.1093/ietcom/e91-b.6.177

Contactless non-leaking waveguide flange realized by bed of nails for millimeter wave applications

Waveguide flanges are typically used to connect and measure high frequency circuits. When good conductive contact is not provided between the joining flange surfaces, currents will flow between them, and thereby causing leakage and losses affecting the circuit performance. This work presents a non-leaking contactless waveguide flange made with bed of nails. The flange does not need any contact when connected to another smooth flange, since the pins surface and the smooth surface together form a stopband suppressing any current and wave propagation between the two joining surfaces of the flanges