3D BEAMSTEERING LOW COMPLEXITY RECONFIGURABLE MULTILEVEL ANTENNA

The main idea of the thesis is to develop a new reconfigurable antenna that makes beamsteering in 3D, with the minimum number of possible switches (maximum 9) and as simple as possible for use in a car vehicle. The design will explore an active dipole located in the center of the antenna (which is fed by a tapered balun), and 4 parasitic dipoles around, placed so that the steering can be done in 9 3D directions according to which parasites we activate by means of switches. The basic idea is to study the physical principle of double reflection, the first reflection due toBeamforming, in its many variants, is a key spatial processing technique to improve user throughput, system capacity, system coverage as well as reducing interference. Simple architectures enabling beamforming either in predefined or arbitrary directions are very desirable for the Fifth Generation of Mobile Communications (5G) to boost power efficiency. Furthermore, it is expected that the number of 5G mobile subscribers grows from 5 million in 2019 to nearly 600 million by 2023, increasing traffic, connections density, and latency which will increase the demand of capacity to the network. Therefore, a broadband intelligent antenna must be at the basis to provide reliable data service, capable to adapt the antenna's capabilities to environment changes. The scope of this thesis focuses on a novel multilevel reconfigurable antenna incorporating beamsteering capabilities by using the lowest number of switches possible

Technologies for injection molded antennas for mass production

Tesi en modalitat de compendi de publicacions. In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of Universitat Politècnica de Catalunya's products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to http://www.ieee.org/publications_standards/publications/rights/rights_link.html to learn how to obtain a License from RightsLink.(English) The deployment of 5G antenna infrastructure and the mandatory adoption of anti-collision radars for automotive cars will require large amount of antennas operating in the millimeter and sub-millimeter wavelength. These antennas are usually arrays and the possibility to manufacture the antenna array including the feeding network and the radiating element as a plastic piece reducing the need to use large (Printed Circuit Boards) PCB’s on expensive dielectric substrates, can be an interesting manufacturing technology. In this regard, waveguide-based antennas can be assembled using plastic technology with a proper metallization procedure. They are more scalable in terms of efficiency than microstrip line (ML) antennas and as the number of antennas in the array increases the gain is not reduced due to the losses in the substrate. In this thesis, the industrial challenges of this technology are addressed. A detailed tolerance study by including the plastic manufacturing errors, typically +-0.1mm, is carried out in order to check the feasibility of plastic antennas to address mass production. The antennas will need to be integrated with the radar chipsets, so a transition between the chip and the waveguide-antennas will be presented. These transitions can act as a direct chip-waveguide launcher, potentially reducing the need of using large substrates, hence reducing the cost of the antenna. Also, the need to apply metal coating is also explored to achieve the desired performance. Conventional techniques such as copper electrodeposition is used. The main drawback is that the copper has a lot of difficulties depositing into right angle surfaces. Eventually, these antennas will have to be integrated in the aesthetics of a car, usually behind a plastic radome (with its respective manufacturing errors as well) that will need to be designed and optimized properly in order to introduce the minimum distorsions to the radar. Optimization based on simulators done with commercial electromagnetic softwares like CST is not feasible due to the required large computation time. In this regard an ad-hoc ray-tracing based simulator has been developed to asses radome induced errors in radar performance. All these industrial problems are taken into account from the design stage where the time, price, fabrication tolerances and radiation requirements have to be compromised at the same time increasing dramatically the design complexity.(Español) El despliegue de infraestructura de antenas 5G y la adopción obligatoria de radares anticolisión para automóviles requerirá una gran cantidad de antenas que operen en longitudes de onda milimétricas y submilimétricas. Estas antenas suelen ser agrupaciones y la posibilidad de fabricar la agrupación de antenas, incluida la red de alimentación y el elemento radiante como una pieza de plástico, lo que reduce la necesidad de usar PCB grandes (placas de circuito impreso) en sustratos dieléctricos costosos, puede ser una tecnología de fabricación interesante. En este sentido, las antenas basadas en guía de ondas se pueden ensamblar utilizando tecnología plástica con un procedimiento de metalización adecuado. Son más escalables en términos de eficiencia que las antenas de línea microstrip (ML) y, a medida que aumenta el número de antenas en el arreglo, la ganancia no se reduce debido a las pérdidas en el sustrato. En esta tesis se abordan los retos industriales de esta tecnología. Se lleva a cabo un estudio de tolerancia detallado que incluye los errores de fabricación de plástico, normalmente +- 0,1 mm, para comprobar la viabilidad de las antenas de plástico para hacer frente a la producción en masa. Las antenas deberán integrarse junto con los chips de radar, por lo que se presentará una transición entre el chip y las antenas de guía de ondas. Estas transiciones pueden actuar como una transición directa de chip-guía, lo que podría reducir la necesidad de usar sustratos grandes y, por lo tanto, reducir el costo de la antena. Además, también se explora la necesidad de aplicar un recubrimiento metálico para lograr el rendimiento deseado. Se utilizan técnicas convencionales como la electrodeposición de cobre. El principal inconveniente es que el cobre tiene muchas dificultades para depositarse en superficies en ángulo recto. Eventualmente, estas antenas deberán integrarse en la estética de un automóvil, generalmente detrás de un radomo de plástico (con sus respectivos errores de fabricación también) que deberá diseñarse y optimizarse adecuadamente para introducir las mínimas distorsiones al radar. La optimización basada en simuladores realizados con software electromagnético comercial como CST no es factible debido al gran tiempo de cálculo requerido. En este sentido, se ha desarrollado un simulador basado en trazado de rayos ad-hoc para evaluar los errores inducidos por el radomo en el rendimiento del radar. Todos estos problemas industriales se tienen en cuenta desde la etapa de diseño donde el tiempo, el precio, las tolerancias de fabricación y los requisitos de radiación tienen que verse comprometidos al mismo tiempo que aumentan drásticamente la complejidad del diseño.Postprint (published version

Constraining Sterile Neutrinos Using Reactor Neutrino Experiments

Models of neutrino mixing involving one or more sterile neutrinos have resurrected their importance in the light of recent cosmological data. In this case, reactor antineutrino experiments offer an ideal place to look for signatures of sterile neutrinos due to their impact on neutrino flavor transitions. In this work, we show that the high-precision data of the Daya Bay experi\-ment constrain the 3+1 neutrino scenario imposing upper bounds on the relevant active-sterile mixing angle $\sin^2 2 \theta_{14} \lesssim 0.06$ at 3$\sigma$ confidence level for the mass-squared difference $\Delta m^2_{41}$ in the range $(10^{-3},10^{-1}) \, {\rm eV^2}$. The latter bound can be improved by six years of running of the JUNO experiment, $\sin^22\theta_{14} \lesssim 0.016$, although in the smaller mass range $\Delta m^2_{41} \in (10^{-4} ,10^{-3}) \, {\rm eV}^2$. We have also investigated the impact of sterile neutrinos on precision measurements of the standard neutrino oscillation parameters $\theta_{13}$ and $\Delta m^2_{31}$ (at Daya Bay and JUNO), $\theta_{12}$ and $\Delta m^2_{21}$ (at JUNO), and most importantly, the neutrino mass hierarchy (at JUNO). We find that, except for the obvious situation where $\Delta m^2_{41}\sim \Delta m^2_{31}$, sterile states do not affect these measurements substantially.Comment: 23 pages, 9 figures, more discussions added, matches the published versio

Process-oriented Iterative Multiple Alignment for Medical Process Mining

Adapted from biological sequence alignment, trace alignment is a process mining technique used to visualize and analyze workflow data. Any analysis done with this method, however, is affected by the alignment quality. The best existing trace alignment techniques use progressive guide-trees to heuristically approximate the optimal alignment in O(N2L2) time. These algorithms are heavily dependent on the selected guide-tree metric, often return sum-of-pairs-score-reducing errors that interfere with interpretation, and are computationally intensive for large datasets. To alleviate these issues, we propose process-oriented iterative multiple alignment (PIMA), which contains specialized optimizations to better handle workflow data. We demonstrate that PIMA is a flexible framework capable of achieving better sum-of-pairs score than existing trace alignment algorithms in only O(NL2) time. We applied PIMA to analyzing medical workflow data, showing how iterative alignment can better represent the data and facilitate the extraction of insights from data visualization.Comment: accepted at ICDMW 201

Ultra-wideband narrow wall waveguide-to-microstrip transition using overlapped patches

An ultrawideband rectangular waveguide to microstrip line transition operating at the whole LMDS and Ka band is presented. The transition is based on exciting three overlapped transversal patches that radiate into the narrow wall of the waveguide, making the design feasible to be used in ¿g/2 spaced phased arrays. Both top-side and bottom-side versions were designed and compared to show their differences. They were validated by means of a manufactured back-to-back (B2B) configuration, with a measured fractional bandwidth of 21.2% (top-side) and 23% (bottom-side). The maximum single transition measured insertion losses were 0.67 dB (top-side) and 0.85 dB (bottom-side) in the whole band of operationThis work was supported by the Spanish “Comision Interministerial de Ciencia y Tecnologia” (CICYT) under projects DI2020-043, Agencia Estatal de Investigación PID2019-107885GBC31/AEI/ 10.13039, and Catalan Research Group 2017 SGR 219.Peer ReviewedPostprint (published version

Evaluation of Trace Alignment Quality and its Application in Medical Process Mining

Trace alignment algorithms have been used in process mining for discovering the consensus treatment procedures and process deviations. Different alignment algorithms, however, may produce very different results. No widely-adopted method exists for evaluating the results of trace alignment. Existing reference-free evaluation methods cannot adequately and comprehensively assess the alignment quality. We analyzed and compared the existing evaluation methods, identifying their limitations, and introduced improvements in two reference-free evaluation methods. Our approach assesses the alignment result globally instead of locally, and therefore helps the algorithm to optimize overall alignment quality. We also introduced a novel metric to measure the alignment complexity, which can be used as a constraint on alignment algorithm optimization. We tested our evaluation methods on a trauma resuscitation dataset and provided the medical explanation of the activities and patterns identified as deviations using our proposed evaluation methods.Comment: 10 pages, 6 figures and 5 table

Welcoming the First Decade of Perovskite Solar Cells

The swift emergence of perovskite solar cells (PSCs) is a “miracle” development in the history of photovoltaics. Since Miyasaka and co‐workers (Toin University of Yokohama, Japan) reported the first use of halide perovskites (HPs) in solar cells in 2009, the past ten years have witnessed a skyrocketing increase in power conversion efficiency (PCE) to 24.2% for single‐junction PSCs and 28.0% for Si‐perovskite tandem solar cells

On incidence energy of a graph

AbstractThe Laplacian-energy like invariant LEL(G) and the incidence energy IE(G) of a graph are recently proposed quantities, equal, respectively, to the sum of the square roots of the Laplacian eigenvalues, and the sum of the singular values of the incidence matrix of the graph G. However, IE(G) is closely related with the eigenvalues of the Laplacian and signless Laplacian matrices of G. For bipartite graphs, IE=LEL. We now point out some further relations for IE and LEL: IE can be expressed in terms of eigenvalues of the line graph, whereas LEL in terms of singular values of the incidence matrix of a directed graph. Several lower and upper bounds for IE are obtained, including those that pertain to the line graph of G. In addition, Nordhaus–Gaddum-type results for IE are established

Survival of the Most Influential Prompts: Efficient Black-Box Prompt Search via Clustering and Pruning

Prompt-based learning has been an effective paradigm for large pretrained language models (LLM), enabling few-shot or even zero-shot learning. Black-box prompt search has received growing interest recently for its distinctive properties of gradient-free optimization, proven particularly useful and powerful for model-as-a-service usage. However, the discrete nature and the complexity of combinatorial optimization hinder the efficiency of modern black-box approaches. Despite extensive research on search algorithms, the crucial aspect of search space design and optimization has been largely overlooked. In this paper, we first conduct a sensitivity analysis by prompting LLM, revealing that only a small number of tokens exert a disproportionate amount of influence on LLM predictions. Leveraging this insight, we propose the Clustering and Pruning for Efficient Black-box Prompt Search (ClaPS), a simple black-box search method that first clusters and prunes the search space to focus exclusively on influential prompt tokens. By employing even simple search methods within the pruned search space, ClaPS achieves state-of-the-art performance across various tasks and LLMs, surpassing the performance of complex approaches while significantly reducing search costs. Our findings underscore the critical role of search space design and optimization in enhancing both the usefulness and the efficiency of black-box prompt-based learning.Comment: Findings of EMNLP 2023. 10 pages, 5 figures, 4 tables (14 pages, 5 figures, 8 tables including references and appendices