1,439 research outputs found

    Cloud System Evolution in the Trades (CSET): Following the Evolution of Boundary Layer Cloud Systems with the NSFNCAR GV

    Get PDF
    The Cloud System Evolution in the Trades (CSET) study was designed to describe and explain the evolution of the boundary layer aerosol, cloud, and thermodynamic structures along trajectories within the North Pacific trade winds. The study centered on seven round trips of the National Science FoundationNational Center for Atmospheric Research (NSFNCAR) Gulfstream V (GV) between Sacramento, California, and Kona, Hawaii, between 7 July and 9 August 2015. The CSET observing strategy was to sample aerosol, cloud, and boundary layer properties upwind from the transition zone over the North Pacific and to resample these areas two days later. Global Forecast System forecast trajectories were used to plan the outbound flight to Hawaii with updated forecast trajectories setting the return flight plan two days later. Two key elements of the CSET observing system were the newly developed High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Cloud Radar (HCR) and the high-spectral-resolution lidar (HSRL). Together they provided unprecedented characterizations of aerosol, cloud, and precipitation structures that were combined with in situ measurements of aerosol, cloud, precipitation, and turbulence properties. The cloud systems sampled included solid stratocumulus infused with smoke from Canadian wildfires, mesoscale cloudprecipitation complexes, and patches of shallow cumuli in very clean environments. Ultraclean layers observed frequently near the top of the boundary layer were often associated with shallow, optically thin, layered veil clouds. The extensive aerosol, cloud, drizzle, and boundary layer sampling made over open areas of the northeast Pacific along 2-day trajectories during CSET will be an invaluable resource for modeling studies of boundary layer cloud system evolution and its governing physical processes

    A surface ocean CO2 reference network, SOCONET and associated marine boundary layer CO2 measurements

    Get PDF
    The Surface Ocean CO2 NETwork (SOCONET) and atmospheric Marine Boundary Layer (MBL) CO2 measurements from ships and buoys focus on the operational aspects of measurements of CO2 in both the ocean surface and atmospheric MBLs. The goal is to provide accurate pCO2 data to within 2 micro atmosphere (μatm) for surface ocean and 0.2 parts per million (ppm) for MBL measurements following rigorous best practices, calibration and intercomparison procedures. Platforms and data will be tracked in near real-time and final quality-controlled data will be provided to the community within a year. The network, involving partners worldwide, will aid in production of important products such as maps of monthly resolved surface ocean CO2 and air-sea CO2 flux measurements. These products and other derivatives using surface ocean and MBL CO2 data, such as surface ocean pH maps and MBL CO2 maps, will be of high value for policy assessments and socio-economic decisions regarding the role of the ocean in sequestering anthropogenic CO2 and how this uptake is impacting ocean health by ocean acidification. SOCONET has an open ocean emphasis but will work with regional (coastal) networks. It will liaise with intergovernmental science organizations such as Global Atmosphere Watch (GAW), and the joint committee for and ocean and marine meteorology (JCOMM). Here we describe the details of this emerging network and its proposed operations and practices

    Video Quality Prediction for Video over Wireless Access Networks (UMTS and WLAN)

    Get PDF
    Transmission of video content over wireless access networks (in particular, Wireless Local Area Networks (WLAN) and Third Generation Universal Mobile Telecommunication System (3G UMTS)) is growing exponentially and gaining popularity, and is predicted to expose new revenue streams for mobile network operators. However, the success of these video applications over wireless access networks very much depend on meeting the user’s Quality of Service (QoS) requirements. Thus, it is highly desirable to be able to predict and, if appropriate, to control video quality to meet user’s QoS requirements. Video quality is affected by distortions caused by the encoder and the wireless access network. The impact of these distortions is content dependent, but this feature has not been widely used in existing video quality prediction models. The main aim of the project is the development of novel and efficient models for video quality prediction in a non-intrusive way for low bitrate and resolution videos and to demonstrate their application in QoS-driven adaptation schemes for mobile video streaming applications. This led to five main contributions of the thesis as follows:(1) A thorough understanding of the relationships between video quality, wireless access network (UMTS and WLAN) parameters (e.g. packet/block loss, mean burst length and link bandwidth), encoder parameters (e.g. sender bitrate, frame rate) and content type is provided. An understanding of the relationships and interactions between them and their impact on video quality is important as it provides a basis for the development of non-intrusive video quality prediction models.(2) A new content classification method was proposed based on statistical tools as content type was found to be the most important parameter. (3) Efficient regression-based and artificial neural network-based learning models were developed for video quality prediction over WLAN and UMTS access networks. The models are light weight (can be implemented in real time monitoring), provide a measure for user perceived quality, without time consuming subjective tests. The models have potential applications in several other areas, including QoS control and optimization in network planning and content provisioning for network/service providers.(4) The applications of the proposed regression-based models were investigated in (i) optimization of content provisioning and network resource utilization and (ii) A new fuzzy sender bitrate adaptation scheme was presented at the sender side over WLAN and UMTS access networks. (5) Finally, Internet-based subjective tests that captured distortions caused by the encoder and the wireless access network for different types of contents were designed. The database of subjective results has been made available to research community as there is a lack of subjective video quality assessment databases.Partially sponsored by EU FP7 ADAMANTIUM Project (EU Contract 214751

    Contributions to Intelligent Scene Understanding of Unstructured Environments from 3D lidar sensors

    Get PDF
    Además, la viabilidad de este enfoque es evaluado mediante la implementación de cuatro tipos de clasificadores de aprendizaje supervisado encontrados en métodos de procesamiento de escenas: red neuronal, máquina de vectores de soporte, procesos gaussianos, y modelos de mezcla gaussiana. La segmentación de objetos es un paso más allá hacia el entendimiento de escena, donde conjuntos de puntos 3D correspondientes al suelo y otros objetos de la escena son aislados. La tesis propone nuevas contribuciones a la segmentación de nubes de puntos basados en mapas de vóxeles caracterizados geométricamente. En concreto, la metodología propuesta se compone de dos pasos: primero, una segmentación del suelo especialmente diseñado para entornos naturales; y segundo, el posterior aislamiento de objetos individuales. Además, el método de segmentación del suelo es integrado en una nueva técnica de mapa de navegabilidad basado en cuadrícula de ocupación el cuál puede ser apropiado para robots móviles en entornos naturales. El diseño y desarrollo de un nuevo y asequible sensor lidar 3D de alta resolución también se ha propuesto en la tesis. Los nuevos MBLs, tales como los desarrollados por Velodyne, están siendo cada vez más un tipo de sensor 3D asequible y popular que ofrece alto ratio de datos en un campo de visión vertical (FOV) limitado. El diseño propuesto consiste en una plataforma giratoria que mejora la resolución y el FOV vertical de un Velodyne VLP-16 de 16 haces. Además, los complejos patrones de escaneo producidos por configuraciones de MBL que rotan se analizan tanto en simulaciones de esfera hueca como en escáneres reales en entornos representativos. Fecha de Lectura de Tesis: 11 de julio 2018.Ingeniería de Sistemas y Automática Resumen tesis: Los sensores lidar 3D son una tecnología clave para navegación, localización, mapeo y entendimiento de escenas en vehículos no tripulados y robots móviles. Esta tecnología, que provee nubes de puntos densas, puede ser especialmente adecuada para nuevas aplicaciones en entornos naturales o desestructurados, tales como búsqueda y rescate, exploración planetaria, agricultura, o exploración fuera de carretera. Esto es un desafío como área de investigación que incluye disciplinas que van desde el diseño de sensor a la inteligencia artificial o el aprendizaje automático (machine learning). En este contexto, esta tesis propone contribuciones al entendimiento inteligente de escenas en entornos desestructurados basado en medidas 3D de distancia a nivel del suelo. En concreto, las contribuciones principales incluyen nuevas metodologías para la clasificación de características espaciales, segmentación de objetos, y evaluación de navegabilidad en entornos naturales y urbanos, y también el diseño y desarrollo de un nuevo lidar rotatorio multi-haz (MBL). La clasificación de características espaciales es muy relevante porque es extensamente requerida como un paso fundamental previo a los problemas de entendimiento de alto nivel de una escena. Las contribuciones de la tesis en este respecto tratan de mejorar la eficacia, tanto en carga computacional como en precisión, de clasificación de aprendizaje supervisado de características de forma espacial (forma tubular, plana o difusa) obtenida mediante el análisis de componentes principales (PCA). Esto se ha conseguido proponiendo un concepto eficiente de vecindario basado en vóxel en una contribución original que define los procedimientos de aprendizaje “offline” y clasificación “online” a la vez que cinco definiciones alternativas de vectores de características basados en PCA

    What Can You Learn from a Cell Phone? Almost Anything!

    Get PDF
    One and a half billion people, all over the world, are walking around with powerful computers in their pockets and purses. The fact is they often do not realize it, because they call them something else. But today's high-end cell phones have the computing power of a mid-1990s personal computer (PC)—while consuming only one one-hundredth of the energy. Even the simplest, voice-only phones have more complex and powerful chips than the 1969 on-board computer that landed a spaceship on the moon. In the United States, it is almost universally acknowledged that computers are essential for 21st-century students. To most educators "computer " means a PC, a laptop, or, in some instances, a personal digital assistant (PDA); cell phones, on the other hand, are more often regarded as bothersome distractions to the learning process. However, it is time to begin thinking of our cell phones as computers—even more powerful in some ways than their bigger cousins. Both have microchips and perform logical functions. The main difference is that the phones began with, and still have, small size, radio transmission, and communication as their core features, expanding out toward calculation and other functions. This has happened at precisely the same time as the calculation machines we call computers have expanded into communication and other areas. Clearly the two are headed toward meeting in the middle; when all the miniaturization problems have been solved, the result will be tiny, fully featured devices that we carry around (or perhaps have implanted i

    Citizen Science approaches for beach litter monitoring

    Get PDF
    Questa tesi dal titolo "Approcci della scienza dei cittadini per il monitoraggio dei rifiuti da spiaggia" si concentra sui rifiuti marini delle spiagge (di seguito MBL). MBL rappresenta un enorme problema che riguarda le aree scientifiche, economiche e sociali. Durante il primo anno di dottorato è stata organizzata e realizzata un'attività pilota di citizen science per il monitoraggio dell'ambiente balneare con studenti delle scuole primarie e secondarie, utilizzando il protocollo MAC-Emerso. Le osservazioni raccolte sono state incluse nel database ufficiale MAC-Emerso. Durante il secondo anno, è stata completata un'analisi bibliometrica sul MBL e i risultati raggiunti sono stati organizzati per la pubblicazione in una rivista peer-reviewed. Inoltre, è stata effettuata un'analisi preliminare del database nazionale MAC-Emerso disponibile. Il terzo anno è stato dedicato alla compilazione di studi e programmi precedenti incentrati sul monitoraggio MBL e sulle campagne di bonifica lungo la costa mediterranea. Tutte le metodologie applicate fino ad oggi sono state analizzate e confrontate nel dettaglio per identificare i punti di forza e di debolezza dei protocolli attuali, il coinvolgimento dei cittadini e le lacune esistenti. La presente tesi è composta da otto capitoli e due articoli e si apre con un'introduzione generale che descrive MBL (Capitolo 1). Il capitolo 2 discute l'obiettivo generale della ricerca di dottorato e riassume gli articoli inclusi nella tesi di dottorato. Il capitolo 3 esamina in dettaglio la strategia marina, mentre il capitolo 4 si concentra sulla scienza dei cittadini e sul protocollo MAC-Emerso. Il capitolo 5 descrive i principali risultati raggiunti, inclusa l'attività pilota di citizen science organizzata e realizzata per il monitoraggio dell'ambiente balneare con gli studenti delle scuole primarie e secondarie che utilizzano il protocollo MAC-Emerso. Il capitolo 6 comprende la raccolta dei due articoli scientifici su MBL realizzati durante le attività di dottorato. Il primo paper (Cesarano et al., 2021) è stato pubblicato su Marine Pollution Bulletin (con ranking Q1), mentre il secondo paper è stato recentemente inviato alla stessa rivista. Il primo esplora la letteratura scientifica globale sull'MBL attraverso un'accurata analisi bibliometrica. Quest'ultimo presenta una revisione sistematica della letteratura corrente sul monitoraggio MBL lungo le coste del Mediterraneo. Insieme, forniscono una revisione completa delle conoscenze scientifiche sull'MBL nella regione mediterranea e offrono spunti interessanti per capire dove si trovano le lacune attuali e cosa sarebbe necessario per sviluppare un monitoraggio più efficiente su scala di bacino a sostegno dei nostri sforzi per affrontare il Sfida MBL. Infine, un'osservazione conclusiva dei risultati complessivi raggiunti nel presente studio è elaborata nel Capitolo 7. Segue una nota sugli altri prodotti non inclusi in questa tesi, ma eseguiti durante il mio periodo di dottorato. Quindi, un elenco di riferimento degli studi menzionati attraverso la tesi conclude questo documento.This thesis entitled “Citizen Science approaches for beach litter monitoring” focuses on Marine Beach Litter (hereafter MBL). MBL represents a huge problem that concerns scientific, economic, and social areas. During the first year of my PhD, a pilot citizen science activity was organized and realized for monitoring beach environment with primary and secondary school students, using the MAC-Emerso protocol. The collected observations were included in the official MAC-Emerso database. During the second year, a bibliometric analysis on the MBL topic has been completed and the achieved results have been organized for publication in a peer-reviewed journal. Furthermore, a preliminary analysis of the available national MAC-Emerso database was carried out. The third year was devoted to compile previous studies and programs focusing on MBL monitoring and cleanup campaigns along the Mediterranean coastline. All the methodologies applied to date have been analysed and compared in detail to identify strengths and weaknesses of current protocols, citizen involvement, and existing gaps. The present thesis consists of eight chapters and two papers and opens with a general introduction describing MBL (Chapter 1). Chapter 2 discusses the overall aim of the PhD research, and summarizes the papers included in the PhD thesis. Chapter 3 examines in detail the Marine Strategy, while Chapter 4 focuses on Citizen Science and the MAC-Emerso protocol. Chapter 5 describes the main results achieved, including the pilot citizen science activity organized and realized for monitoring beach environment with primary and secondary school students using the MAC-Emerso protocol. Chapter 6 includes the collection of the two scientific papers on MBL realized during the PhD activities. The first paper (Cesarano et al., 2021) has been published in Marine Pollution Bulletin (with Q1 ranking), while the second paper has been recently submitted to the same journal. The former explores the global scientific literature on MBL through an accurate bibliometric analysis. The latter presents a systematic review of current literature concerning MBL monitoring along the Mediterranean coasts. Together, they do provide a comprehensive review of the scientific knowledge on MBL in the Mediterranean region and offer interesting insights to understand where current gaps lie, and what would be needed to develop a basin-scale more efficient monitoring in support of our efforts to tackle the MBL challenge. Finally, a concluding remark of the overall results achieved in the present study is elaborated in Chapter 7. A note about the other products not included in this thesis, but performed during my PhD period, follows. Then, a reference list of the studies mentioned through the thesis ends this document
    corecore