Feature-based object tracking in maritime scenes.

A monitoring of presence, location and activity of various objects on the sea is essential for maritime navigation and collision avoidance. Mariners normally rely on two complementary methods of the monitoring: radar and satellite-based aids and human observation. Though radar aids are relatively accurate at long distances, their capability of detecting small, unmanned or non-metallic craft that generally do not reflect radar waves sufficiently enough, is limited. The mariners, therefore, rely in such cases on visual observations. The visual observation is often facilitated by using cameras overlooking the sea that can also provide intensified infra-red images. These systems or nevertheless merely enhance the image and the burden of the tedious and error-prone monitoring task still rests with the operator. This thesis addresses the drawbacks of both methods by presenting a framework consisting of a set of machine vision algorithms that facilitate the monitoring tasks in maritime environment. The framework detects and tracks objects in a sequence of images captured by a camera mounted either on a board of a vessel or on a static platform over-looking the sea. The detection of objects is independent of their appearance and conditions such as weather and time of the day. The output of the framework consists of locations and motions of all detected objects with respect to a fixed point in the scene. All values are estimated in real-world units, i. e. location is expressed in metres and velocity in knots. The consistency of the estimates is maintained by compensating for spurious effects such as vibration of the camera. In addition, the framework continuously checks for predefined events such as collision threats or area intrusions, raising an alarm when any such event occurs. The development and evaluation of the framework is based on sequences captured under conditions corresponding to a designated application. The independence of the detection and tracking on the appearance of the sceneand objects is confirmed by a final cross-validation of the framework on previously unused sequences. Potential applications of the framework in various areas of maritime environment including navigation, security, surveillance and others are outlined. Limitations to the presented framework are identified and possible solutions suggested. The thesis concludes with suggestions to further directions of the research presented

RIANN—A robust neural network outperforms attitude estimation filters

Inertial-sensor-based attitude estimation is a crucial technology in various applications, from human motion tracking to autonomous aerial and ground vehicles. Application scenarios differ in characteristics of the performed motion, presence of disturbances, and environmental conditions. Since state-of-the-art attitude estimators do not generalize well over these characteristics, their parameters must be tuned for the individual motion characteristics and circumstances. We propose RIANN, a ready-to-use, neural network-based, parameter-free, real-time-capable inertial attitude estimator, which generalizes well across different motion dynamics, environments, and sampling rates, without the need for application-specific adaptations. We gather six publicly available datasets of which we exploit two datasets for the method development and the training, and we use four datasets for evaluation of the trained estimator in three different test scenarios with varying practical relevance. Results show that RIANN outperforms state-of-the-art attitude estimation filters in the sense that it generalizes much better across a variety of motions and conditions in different applications, with different sensor hardware and different sampling frequencies. This is true even if the filters are tuned on each individual test dataset, whereas RIANN was trained on completely separate data and has never seen any of these test datasets. RIANN can be applied directly without adaptations or training and is therefore expected to enable plug-and-play solutions in numerous applications, especially when accuracy is crucial but no ground-truth data is available for tuning or when motion and disturbance characteristics are uncertain. We made RIANN publicly available.DFG, 414044773, Open Access Publizieren 2021 - 2022 / Technische Universität Berli

Non-contact measures to monitor hand movement of people with rheumatoid arthritis using a monocular RGB camera

Hand movements play an essential role in a person’s ability to interact with the environment. In hand biomechanics, the range of joint motion is a crucial metric to quantify changes due to degenerative pathologies, such as rheumatoid arthritis (RA). RA is a chronic condition where the immune system mistakenly attacks the joints, particularly those in the hands. Optoelectronic motion capture systems are gold-standard tools to quantify changes but are challenging to adopt outside laboratory settings. Deep learning executed on standard video data can capture RA participants in their natural environments, potentially supporting objectivity in remote consultation. The three main research aims in this thesis were 1) to assess the extent to which current deep learning architectures, which have been validated for quantifying motion of other body segments, can be applied to hand kinematics using monocular RGB cameras, 2) to localise where in videos the hand motions of interest are to be found, 3) to assess the validity of 1) and 2) to determine disease status in RA. First, hand kinematics for twelve healthy participants, captured with OpenPose were benchmarked against those captured using an optoelectronic system, showing acceptable instrument errors below 10°. Then, a gesture classifier was tested to segment video recordings of twenty-two healthy participants, achieving an accuracy of 93.5%. Finally, OpenPose and the classifier were applied to videos of RA participants performing hand exercises to determine disease status. The inferred disease activity exhibited agreement with the in-person ground truth in nine out of ten instances, outperforming virtual consultations, which agreed only six times out of ten. These results demonstrate that this approach is more effective than estimated disease activity performed by human experts during video consultations. The end goal sets the foundation for a tool that RA participants can use to observe their disease activity from their home.Open Acces

An Investigation of Reliability Models for Ceramic Matrix Composites and their Implementation into Finite Element Codes

The development of modeling approaches for the failure analysis of ceramic-based material systems used in high temperature environments was the primary objective of this research effort. These materials have the potential to support many key engineering technologies related to the design of aeropropulsion systems. Monolithic ceramics exhibit a number of useful properties such as retention of strength at high temperatures, chemical inertness, and low density. However, the use of monolithic ceramics has been limited by their inherent brittleness and a large variation in strength. This behavior has motivated material scientists to reinforce the monolithic material with a ceramic fiber. The addition of a second ceramic phase with an optimized interface increases toughness and marginally increases strength. The primary purpose of the fiber is to arrest crack growth, not to increase strength. The material systems of interest in this research effort were laminated ceramic matrix composites, as well as two- and three- dimensional fabric reinforced ceramic composites. These emerging composite systems can compete with metals in many demanding applications. However, the ongoing metamorphosis of ceramic composite material systems, and the lack of standardized design data has in the past tended to minimize research efforts related to structural analysis. Many structural components fabricated from ceramic matrix composites (CMC) have been designed by "trial and error." The justification for this approach lies in the fact that during the initial developmental phases for a material system fabrication issues are paramount. Emphasis is placed on demonstrating feasibility rather than fully understanding the processes controlling mechanical behavior. This is understandable during periods of rapid improvements in material properties for any composite system. But to avoid the ad hoc approach, the analytical methods developed under this effort can be used to develop rational structural design protocols

Investigation of coding and equalization for the digital HDTV terrestrial broadcast channel

Includes bibliographical references (p. 241-248).Supported by the Advanced Telecommunications Research Program.Julien J. Nicolas

Adaptive techniques for signal enhancement in the human electroencephalogram

This thesis describes an investigation of adaptive noise cancelling applied to human brain evoked potentials (EPs), with particular emphasis on visually evoked responses. The chief morphological features and signal properties of EPs are described. Consideration is given to the amplitude and spectral properties of the underlying spontaneous electroencephalogram and the importance of noise reduction techniques in EP studies is empnasised. A number of methods of enhancing EP waveforms are reviewed in the light of the known limitations of coherent signal averaging. These are shown to oe generally inadequate for enhancing individual EP responses. The theory of adaptive filters is reviewed with particular reference to adaptive transversal filters usiny the Widrow-Hoff algorithm. The theory of adaptive noise cancelling using correlated reference sources is presented, and new work is described which relates canceller performance to the magnitude-squared coherence function of the input signals. A novel filter structure, the gated adaptive filter, is presented and shown to yield improved cancellation without signal distortion when applied to repetitive transient signals in stationary noise under the condition of fast adaption. The signal processing software available is shown to be inadequate, and a comprehensive Fortran program developed for use on a PDP-11 computer is described. The properties of human visual evoked potentials and the EEO are investigated in two normal adults using a montage of 7 occipital electrodes. Signal enhancement of EPs is shown to be possible oy adaptive noise cancelling, and improvements in signal to noise in the range 2-10 dB are predicted. A discussion of filter strategies is presented, and a detailed investiyation of adaptive noise cancel liny performed usiny a ranye of typical EP data. Assessment of the results confirms the proposal that substantial improvement in sinyle EP response recoynition is achieved by this technique

Challenges and New Trends in Power Electronic Devices Reliability

The rapid increase in new power electronic devices and converters for electric transportation and smart grid technologies requires a deepanalysis of their component performances, considering all of the different environmental scenarios, overload conditions, and high stressoperations. Therefore, evaluation of the reliability and availability of these devices becomes fundamental both from technical and economicalpoints of view. The rapid evolution of technologies and the high reliability level offered by these components have shown that estimating reliability through the traditional approaches is difficult, as historical failure data and/or past observed scenarios demonstrate. With the aim topropose new approaches for the evaluation of reliability, in this book, eleven innovative contributions are collected, all focusedon the reliability assessment of power electronic devices and related components

THz: Research Frontiers for New Sources, Imaging and Other Advanced Technologies

The THz region of the electromagnetic spectrum is a frontier research area involving application of many disciplines, from outdoor to indoor communications, security, drug detection, biometrics, food quality control, agriculture, medicine, semiconductors, and air pollution. THz research is highly demanding in term of sources with high power and time resolution, detectors, and new spectrometer systems. Many open questions still exist regarding working at THz frequencies; many materials exhibit unusual or exotic properties in the THz domain, and researchers need new methodologies to exploit these opportunities. This book contains original papers dealing with emerging applications, new devices, sources and detectors, and materials with advanced properties for applications in biomedicine, cultural heritage, technology, and space

Northern hemisphere blockings and their impacts over the european continent : historical overview and associated mechanisms

Tese de doutoramento, Ciências Geofísicas e da Geoinformação (Meteorologia), Universidade de Lisboa, Faculdade de Ciências, 2017Blocking high pressure systems are large-scale atmospheric circulation patterns with meteorological impacts that vary across regions and seasons, depending on the blocking location, spatial characteristics and temporal length. While blocking episodes are an important component of intra-seasonal and inter-annual variability at mid-latitudes, particularly in Europe, previous studies have mostly focused on characterizing European blocking impacts on either winter or summer seasons. In this thesis, a thorough characterization of Euro-Atlantic blocking occurrence within different longitudinal sectors (Atlantic, European and Russian) was performed, followed by a comprehensive analysis of their seasonal impacts on temperature and on the precipitation regimes of the European continent and specific sub-regions, with particular emphasis on Iberia, and on extreme events. In order to distinguish high-latitude blocking from other common high pressure systems affecting Europe, namely sub-tropical ridges, a novel ridge detection scheme was developed. Ridges do not require a wave-breaking occurrence as blockings do, although they are frequent precursors of wave-breaking, which may lead to blocking. Thus, as an additional novelty, this thesis also characterizes the distinctive seasonal impacts associated with sub-tropical ridges occurring at different longitudinal sectors of the Euro-Atlantic region. Finally, an assessment of the involved mechanisms behind the temperature and precipitation responses to blocking is also carried out. This included for precipitation the role of cyclonic activity (storm-tracks and cut-off lows), moisture transport, and large-scale atmospheric instability, while for temperature the focus was on the role played by horizontal advection, subsidence and imbalances in various radiation budgets. This distinction clarifies that most extreme heat episodes in southern Europe and Mediterranean areas should not be attributed to blockings, but rather to ridges. In central and northern areas of the continent, both regimes are responsible for warm conditions in summer, due to enhanced radiative heating and increased subsidence. During winter, blocking and ridges lead to opposite temperature responses. Blocking reinforces cold northerly advection in its eastern flank, thus promoting European cold winter spells, especially those located in the eastern Atlantic and western Europe, while mild Atlantic flows associated to ridge patterns result in warmer conditions. Regarding the impacts on precipitation, blocking and ridges are associated with a marked northsouth dipole for the three considered longitudinal sectors of occurrence. While blocking patterns force a split of the storm-track, ridges are associated with a stronger zonal flow at higher latitudes. Thus, negative (positive) precipitation anomalies during blocks occur at higher (lower) latitudes. Enhanced atmospheric instability and cyclonic activity south of blocking centers relate very well with increased rainfall in southern Europe, including Iberia, where torrential regimes are more relevant in the precipitation totals. This dipole is reversed during ridges, which lead to dry conditions in southern Europe. The seasonal analysis further reveals that winters characterized by high frequencies of blocking (ridge) occurrence present above (below) average snow covered soils. Blocking/ridge impacts on temperature and precipitation have also additional effects on meteorological and climate extreme events with large socio economic impacts. Thus, the results show a blocking/ridge role at different time-scales in controlling a significant part of wildfire inter annual variability in Mediterranean areas. Meteorological pre-conditioning raises vegetation stress during dry winters, while increased ridge and blocking occurrence in summer fosters meteorological conditions which are prone to fire ignition and spread. Finally, outputs from state-of-the-art General Circulation Models raise the challenge to develop further these automated schemes for blocking/ridges detection, as their representation in climate models is crucial to understand impacts towards the later decades of the 21st century. Summing up, the main novelties and achievements of this thesis are: 1) the clear disentanglement between blocks and ridges; 2) the seasonal analyses of specific regional impacts resulting from different locations of blocking/ridge structures; 3) the detailed analysis of dynamical/physical forcing mechanisms associated to each considered weather pattern.Apesar de não existir uma definição unanimemente aceite para o conceito de bloqueio atmosférico, este pode ser descrito como uma supressão do fluxo zonal devido à presença de um sistema de alta pressão. Esta circulação anticiclónica, normalmente localizada nas latitudes onde se observa a corrente de jato polar, apresenta uma dimensão espacial de larga-escala, é geralmente quase-estacionária, e tem um tempo de vida útil entre vários dias a várias semanas. Os sectores orientais dos oceanos Atlântico e Pacífico são geralmente as regiões de ocorrência preferencial de bloqueios no Hemisfério Norte. A ocorrência de bloqueios atmosféricos está diretamente associada a condições prolongadas de tempo seco e estável nas regiões diretamente localizadas sob o sistema de altas pressões. O seu posicionamento geralmente origina uma divisão em dois ramos da corrente de jato. Esta perturbação do habitual padrão zonal resulta em alterações significativas das condições meteorológicas a outras latitudes (tanto meridional como setentrional) distintas da zona diretamente afetada pela posição central do bloqueio. Torna-se necessária assim uma compreensão mais detalhada da climatologia associada aos bloqueios atmosféricos centrados no setor Euro-Atlântico, com especial ênfase aos impactos específicos associados às diferentes localizações que os seus centros de ação possam ter. Apesar de serem um fenómeno que ocorre à escala sinóptica, os bloqueios podem implicar impactos climáticos muito distintos à escala regional, ou mesmo local. Desta forma, um dos principais objetivos desta tese centra-se na elaboração de uma climatologia completa da sua ocorrência, e na respetiva caracterização dos impactos climáticos regionais resultantes da ocorrência de bloqueios em diferentes sectores longitudinais: Atlântico (ATL; 30W-0W), Europeu (EUR; 0E-30E) e Russo (RUS; 30E-60E). Tendo-se verificado na literatura uma certa confusão entre bloqueio de alta latitude e outros sistemas comuns de alta pressão que afetam a Europa, nomeadamente as cristas sub-tropicais, foi considerado prioritário obter um novo catálogo de cristas de alta pressão para o setor Euro-Atlântico. Desta forma, um segundo objetivo central da tese foi o do desenvolvimento de um novo algoritmo automático de deteção de cristas sub-tropicais, que permita assim realizar uma clara distinção fenomenológica e dos impactos destes dois padrões atmosféricos (bloqueios versus cristas). Assim, a compreensão das condições sinópticas e dos mecanismos físicos envolvidos em cada um destes padrões é também tema central desta tese. No caso da precipitação, esta análise de mecanismos incluiu o papel da atividade ciclónica (storm-tracks e cut-off lows), do transporte de humidade e da instabilidade atmosférica em larga escala. Para avaliar os impactos na temperatura analisou-se a contribuição da advecção horizontal, da subsidência e das alterações nos vários balanços radiativos. A desagregação bloqueios-cristas permite distinguir fenomenologias por vezes confundidas na literatura, nomeadamente aquando da análise de episódios de calor extremo no sul da Europa. Verifica-se dos resultados obtidos que, devido a uma clara distinção no posicionamento latitudinal dos centros de ação entre bloqueios e cristas, as respostas na temperatura associadas a cada padrão são também bem distintas, sendo estas diferenças particularmente notáveis no inverno. De uma forma geral, nesta estação, os bloqueios (essencialmente os centrados nos sectores ATL e EUR) resultam em valores das temperaturas do ar bastante abaixo da média, provocadas pela advecção de ar frio de latitudes mais elevadas ao longo do flanco este dos anticiclones. Em oposição, as cristas originam anomalias positivas na temperatura na maior parte do continente europeu, essencialmente como resultado do transporte de massas de ar de origem Atlântica, e de uma redução do arrefecimento radiativo, associado ao aumento da nebulosidade. Durante o verão, ambos os padrões atmosféricos estão associados a temperaturas acima da média em vastas áreas da Europa central e do norte. Em contrapartida, nas regiões mais a sul, e em particular na área da bacia do Mediterrâneo, as cristas controlam a ocorrência de dias extremamente quentes (usualmente identificados como ondas de calor). No verão é também de salientar o papel dominante do aquecimento radiativo solar (sob condições de céu limpo) como principal impulsionador destas anomalias positivas de temperatura em dias de ocorrência de bloqueio/crista, particularmente para os sistemas localizados sobre áreas continentais. Relativamente aos impactos nos regimes de precipitação, existe um claro dipolo norte-sul ao analisar as anomalias associadas a dias de bloqueio/crista. A ocorrência de bloqueios leva a uma redução da precipitação na metade norte do continente Europeu (em algumas áreas superior a 50%) devido ao bloqueio dos sistemas depressionários de médias-latitudes (e do correspondente transporte de humidade) provenientes do Atlântico. No entanto, esta configuração sinóptica leva a um aumento da precipitação (relativamente à média) nas zonas mais a sul, fundamentalmente relacionado com o desvio do storm-track nesta direção, e a um consequente aumento da instabilidade atmosférica e da convecção. Este padrão resulta numa clara mudança nas distribuições de regimes de precipitação nos países do sul da Europa, e demonstra também a ligação entre bloqueios atmosféricos e os regimes de precipitação torrencial na área do Mediterrâneo. Em padrões de fluxo zonal intenso as anomalias da precipitação são no geral opostas às encontradas durante bloqueios, originando um deficit de precipitação no sul da Europa. No contexto dos vários regimes possíveis de fluxo zonal forte, as cristas sub-tropicais estão associadas a condições particularmente secas nos países do sul da Europa. Isto naturalmente também se aplica à Península Ibérica, onde os totais anuais de precipitação dependem largamente da atividade frontal de origem Atlântica (em particular nos meses de inverno), sendo esta afastada da região durante a ocorrência de cristas nos sectores ATL e EUR. Neste contexto, mostra-se crucial o recurso a bases de dados de alta-resolução com uma densidade de estações muito mais elevada, permitindo uma análise regional mais detalhada para o domínio da Península Ibérica. Os bloqueios centrados em latitudes elevadas, em particular os que ocorrem no sector ATL, são responsáveis por invernos com maior cobertura de neve no continente Europeu (até cerca de 50% mais dias com a superfície coberta de neve na Europa central), devido a uma maior frequência de dias frios sob os fluxos de norte associados à circulação anticiclónica. Por outro lado, a ocorrência de cristas nos sectores ATL e EUR (que estão associadas a dias de inverno bastante amenos) impõe uma frequência muito mais baixa de dias com neve no solo. Foi também concluído que os padrões de bloqueio/crista exercem um efeito regulador importante na variabilidade inter-anual de incêndios florestais. Mostra-se que o feedback existente entre a ocorrência destes padrões atmosféricos, a ocorrência de secas, e os incêndios florestais, acontece a diferentes escalas temporais. Nos meses antecedentes à época de incêndios, uma frequência superior ao normal de cristas (bloqueios) é responsável por valores de precipitação abaixo (acima) da média no sul da Europa, aumentando a vulnerabilidade da vegetação. Durante a própria época de incêndios, este padrão atmosférico está associado a condições anomalamente quentes e secas que promovem a ignição e fácil propagação do fogo. Finalmente, no contexto das alterações climáticas, verificou-se que nas últimas décadas a frequência de cristas sub-tropicais aumentou bastante no sul da Europa. As projeções futuras dos Modelos de Circulação Geral sugerem uma expansão para norte das altas pressões subtropicais (associadas à expansão da célula de Hadley). Por outro lado, não existem sinais dinâmicos de alterações muito significativas na frequência e localização dos bloqueios de alta latitude no sector Euro-Atlântico, exceto uma ligeira tendência de deslocamento para nordeste na sua região preferencial de ocorrência. Pretende-se como trabalho futuro utilizar também uma abordagem dinâmica (não apenas baseada em campos de anomalia) para o algoritmo de deteção de cristas, que permitirá uma maior confiança na extrapolação para cenários futuros

In silico tumor-targeting technologies for the evasion of acidity-induced multidrug resistance

The physiology of tumors is tied to MDR mechanisms that hamper chemotherapeutic effects, particularly passive membrane crossing compounds, like hydrophobic Lewis base drugs. Although the lysosomal entrapment phenomena remains to be fully understood, this pH-dependent MDR mechanism induces drug sequestration in the acidic lysosomal lumen. Overcoming the MDR requires multi-pronged therapies, which often overlook an ubiquitous tumor trait: the extracellular acidity of the tumor microenvironment (TME). To address this, pHLIP peptides have emerged as an acidity-selective technology for tumor-targeting drug delivery. We focused on refining our protocols with enhanced sampling techniques and tumor-like features to improve the predictive abilities of the CpHMD-L methodology and augment the realism of these biomolecular models, thus bridging the gap to in vivo and cellular conditions. The optimized protocol coupled the CpHMD-L method with a pHRE scheme, providing a robust baseline. Then, we applied the protocol to study the diverging therapeutic efficiency of the wt and an over-performing Var3 peptide. A novel implementation of a pH gradient CpHMD-L method successfully reproduced experimental performances, thus elucidating pivotal residues electrostatic networks that dictate peptides thermodynamic stability in TME conditions. A multi-peptide study highlighted the remarkable effects of permuting arginines in modulating the local vicinity of key aspartates. These findings heavily correlate with their tumor-targeting performance, supporting more rational and in silico-based approaches to peptide design. Finally, the pH-dependent mechanism of lysosomal entrapment was modelled, hinting at the important role of acidity in Lewis base drugs membrane intercalation. Additional pH-dependent permeability calculations, using a novel US-CpHMD method, identified the TME acidity as an additional MDR defense mechanism that impairs clinical efficiency. It also revealed an intrinsic flaw of these compounds, since they preferably target healthy cells. These findings have important implications in rational drug design, especially of conjugated therapies with pHLIP-like drug delivery systems to overcome these challenges