10,212 research outputs found

    Beam scanning by liquid-crystal biasing in a modified SIW structure

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    A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

    DATA AUGMENTATION FOR SYNTHETIC APERTURE RADAR USING ALPHA BLENDING AND DEEP LAYER TRAINING

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    Human-based object detection in synthetic aperture RADAR (SAR) imagery is complex and technical, laboriously slow but time critical—the perfect application for machine learning (ML). Training an ML network for object detection requires very large image datasets with imbedded objects that are accurately and precisely labeled. Unfortunately, no such SAR datasets exist. Therefore, this paper proposes a method to synthesize wide field of view (FOV) SAR images by combining two existing datasets: SAMPLE, which is composed of both real and synthetic single-object chips, and MSTAR Clutter, which is composed of real wide-FOV SAR images. Synthetic objects are extracted from SAMPLE using threshold-based segmentation before being alpha-blended onto patches from MSTAR Clutter. To validate the novel synthesis method, individual object chips are created and classified using a simple convolutional neural network (CNN); testing is performed against the measured SAMPLE subset. A novel technique is also developed to investigate training activity in deep layers. The proposed data augmentation technique produces a 17% increase in the accuracy of measured SAR image classification. This improvement shows that any residual artifacts from segmentation and blending do not negatively affect ML, which is promising for future use in wide-area SAR synthesis.Outstanding ThesisMajor, United States Air ForceApproved for public release. Distribution is unlimited

    Vertical heterogeneity of hydrocarbon-degrading bacteria in a core sediment sample from the Central Indian Ridge

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    Hydrocarbons are ubiquitous in marine environments and might fuel hydrocarbon-metabolizing microbes in the ocean. Numerous studies have documented microbial hydrocarbon degradation in water columns and deep-sea surface sediment. However, the degradation potential and biogeochemical cycling of hydrocarbons in subsurface sediments remain largely unknown. In this study, we used two different hydrocarbons, n-hexadecane (HEX) and methylcyclohexane (MCH), to investigate the distribution and diversity of hydrocarbon-consuming bacteria in a core sediment sample from the Central Indian Ridge (CIR), which is adjacent to mid-ridge hydrothermal vents in the Indian Ocean. We observed different vertical profiles of HEX- and MCH-degrading bacteria in the core sediments. Specifically, HEX-degrading bacteria were universally distributed, while MCH-degrading bacteria were found only in the intermediate layers of the core sediments. Changing factors including dissolved oxygen might affect the natural distribution of different hydrocarbon consumers. We found that a novel species of the genus C1-B045 might play a pivotal role in metabolizing MCH in the CIR deep biosphere. Through amino acid identity comparison with published sequences, we determined that C1-B045 harbors two novel classes of cyclohexanone monooxygenases involved in MCH metabolism. This study sheds light on the structure and function of hydrocarbon-consuming microbes in deep biospheres

    KYT2022 Finnish Research Programme on Nuclear Waste Management 2019–2022 : Final Report

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    KYT2022 (Finnish Research Programme on Nuclear Waste Management 2019–2022), organised by the Ministry of Economic Affairs and Employment, was a national research programme with the objective to ensure that the authorities have sufficient levels of nuclear expertise and preparedness that are needed for safety of nuclear waste management. The starting point for public research programs on nuclear safety is that they create the conditions for maintaining the knowledge required for the continued safe and economic use of nuclear energy, developing new know-how and participating in international collaboration. The content of the KYT2022 research programme was composed of nationally important research topics, which are the safety, feasibility and acceptability of nuclear waste management. KYT2022 research programme also functioned as a discussion and information-sharing forum for the authorities, those responsible for nuclear waste management and the research organizations, which helped to make use of the limited research resources. The programme aimed to develop national research infrastructure, ensure the continuing availability of expertise, produce high-level scientific research and increase general knowledge of nuclear waste management

    Identification of patterns for space-time event networks

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    This paper provides new tools for analyzing spatio-temporal event networks. We build time series of directed event networks for a set of spatial distances, and based on scan-statistics, the spatial distance that generates the strongest change of event network connections is chosen. In addition, we propose an empirical random network event generator to detect significant motifs throughout time. This generator preserves the spatial configuration but randomizes the order of the occurrence of events. To prevent the large number of links from masking the count of motifs, we propose using standardized counts of motifs at each time slot. Our methodology is able to detect interaction radius in space, build time series of networks, and describe changes in its topology over time, by means of identification of different types of motifs that allows for the understanding of the spatio-temporal dynamics of the phenomena. We illustrate our methodology by analyzing thefts occurred in Medellín (Colombia) between the years 2003 and 2015.Work supported by Red de Violencia y Criminalidad - Universidad Nacional Abierta y a Distancia UNAD, Bogotá Colombia and Universidad Nacional de Colombia sede Bogotá

    CITIES: Energetic Efficiency, Sustainability; Infrastructures, Energy and the Environment; Mobility and IoT; Governance and Citizenship

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    This book collects important contributions on smart cities. This book was created in collaboration with the ICSC-CITIES2020, held in San José (Costa Rica) in 2020. This book collects articles on: energetic efficiency and sustainability; infrastructures, energy and the environment; mobility and IoT; governance and citizenship

    Recent Advances in Single-Particle Tracking: Experiment and Analysis

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    This Special Issue of Entropy, titled “Recent Advances in Single-Particle Tracking: Experiment and Analysis”, contains a collection of 13 papers concerning different aspects of single-particle tracking, a popular experimental technique that has deeply penetrated molecular biology and statistical and chemical physics. Presenting original research, yet written in an accessible style, this collection will be useful for both newcomers to the field and more experienced researchers looking for some reference. Several papers are written by authorities in the field, and the topics cover aspects of experimental setups, analytical methods of tracking data analysis, a machine learning approach to data and, finally, some more general issues related to diffusion

    Technologies and Applications for Big Data Value

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    This open access book explores cutting-edge solutions and best practices for big data and data-driven AI applications for the data-driven economy. It provides the reader with a basis for understanding how technical issues can be overcome to offer real-world solutions to major industrial areas. The book starts with an introductory chapter that provides an overview of the book by positioning the following chapters in terms of their contributions to technology frameworks which are key elements of the Big Data Value Public-Private Partnership and the upcoming Partnership on AI, Data and Robotics. The remainder of the book is then arranged in two parts. The first part “Technologies and Methods” contains horizontal contributions of technologies and methods that enable data value chains to be applied in any sector. The second part “Processes and Applications” details experience reports and lessons from using big data and data-driven approaches in processes and applications. Its chapters are co-authored with industry experts and cover domains including health, law, finance, retail, manufacturing, mobility, and smart cities. Contributions emanate from the Big Data Value Public-Private Partnership and the Big Data Value Association, which have acted as the European data community's nucleus to bring together businesses with leading researchers to harness the value of data to benefit society, business, science, and industry. The book is of interest to two primary audiences, first, undergraduate and postgraduate students and researchers in various fields, including big data, data science, data engineering, and machine learning and AI. Second, practitioners and industry experts engaged in data-driven systems, software design and deployment projects who are interested in employing these advanced methods to address real-world problems

    The search for biomarkers in the growth prediction of the West Coast Rock Lobster, Jasus lalandii

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    Thesis (PhDAgric)--Stellenbosch University, 2022.ENGLISH ABSTRACT: The West Coast rock lobster (WCRL) Jasus lalandii is a key ecological species and an important fisheries resource in South Africa. The resource is heavily depleted to 1.8% of pristine levels. The fishery is managed according to an operational management procedure to sustainably rebuild the stock, using an annual catch limit and effort control, determined from Catch per Unit Effort, fisheries independent abundance index and growth data. Since these derive from the preceding season, the present research aimed to identify timelier predictors for the next season. The first part of this study analysed biological parameters of male and female WCRL of male commercial size over two years to determine reserve accumulation during two growth (moult) and reproductive (ovarian) cycles. A historically fast-growth- and a slow-growth area were compared - in relation to their annual male somatic growth rate. Moreover, moult stage and biochemistry of hepatopancreas and ovaries were investigated from the fast growth area. The second part specifically investigated reserve accumulation in the high-growth area with a focus on lipid reserves. The study confirmed that annual growth increment in Hout Bay is still about 1 mm higher than at Olifantsbos and inter-annual differences persist within areas. Growth remains at the low level that continues since 1987, indicating that factors for slow growth persist. Results also confirmed seasonal reserve accumulation in male hepatopancreas in preparation for moult/growth in both areas, whereas there was no such seasonality in female hepatopancreas. Concomitant with male hepatopancreas size, female gonad size increased from a minimum in winter to a maximum shortly before spawning. Reserve accumulation varied inter-annually and in extent and timing for both genders. Lipids and proteins accumulated during the moult cycle in male hepatopancreas and in ovaries but not in female hepatopancreas. During the ovarian cycle, reserves accumulated in the ovaries but not in the female hepatopancreas. Some indications of an involvement of the female abdominal muscle in reproduction (ovary maturation) were revealed: It is up to 8% of body size larger than in males and its size declines as ovary cycle progresses. During ovary maturation, females from the Hout Bay area had 42 – 120% more lipids available (total in hepatopancreas and ovaries) than males, meaning that a) females have a higher food consumption rate, b) the area provides sufficient food to support both growth and reproduction, and c) there is surplus food available for males to support optimal somatic growth. In conclusion, females do not need to (completely) prioritise partition of reserve between growth (ovary) and reproduction (hepatopancreas) in this area. The fatty acid profile of male and female hepatopancreas and female gonads did not change during accumulation and no changes in fatty acid profiles occurred during both moult- and reproductive cycles. Presumably, the quality of the available food in the fishing area is unchanged during reserve accumulation and optimal for growth and reproduction. The project aimed at the identification of potential predictors for male somatic growth as an input for annual catch determination. Based on the prerequisite that a potential predictor must display distinct seasonal variation, several parameters were investigated. However, many of them, such as moult stage and fatty acid profile were found unsuitable. Only three sets of data emerged that have the potential to serve as future predictors: 1) lipid accumulation for growth in the male hepatopancreas, 2) reserve accumulation for reproduction in the female gonads and 3) the difference between male and female lobsters in total available lipids. Only 1) correlated well with growth increment during subsequent moult in the area. However, 2) and 3) have strong potential but require additional research. Although these results are not yet robust enough to qualify for the use in stock assessment, they provide important initial information for the development of a predictor for male growth increment in the subsequent moult. The project also produced important information to design a future research strategy to answer remaining questions and provide further advice for fisheries management of the WCRL resource.AFRIKAANSE OPSOMMING: Die Weskus rotskreef (WCRL), Jasus lalandii, is ‘n ekologies sowel as ekonomies belangrike kreefspesie in Suid-Afrika. Huidige getalle van die spesie is slegs sowat 1.8% van die vlakke wat verwag sou word in ongerepte toestande. Die verwydering van die kreefspesie word tans streng bestuur om in ‘n volhoubare poging om getalle van die spesie te laat toeneem. Aangesien jaarlikse limiete bereken word deur gebruik te maak van die vorige jaar se data, is die doel van hierdie navorsing om akkurate voorspellings vir die volgende seisoen te vergemaklik. In die eerste gedeelte van die studie is die biologiese parameters van manlike sowel as wyfie krewe met kommersiële grootte bo 2 jaar ouderdom gebruik om reserwe opeenhoping gedurende twee groei -(dop verwerp) en voortplantingsiklusse te bepaal. Data vanaf histories vinnig sowel as stadige groei areas is vergelyk in verhouding met die jaarlikse manlike somatiese groei tempo. Die groei (dop verwerp) sowel as biochemie van die hepatopankreas en eierstokke in die area met vinnige groei is bestudeer. In die tweede deel van die studie, is spesifiek gefokus op reserwe lipied akkumulasie in die area met vinnige groei. Die studie het bevind dat die jaarlikse toename in die Houtbaai area ongeveer 1 mm hoër is as in die Olifantsbos area. Jaar tot jaar verskille volhard in die verskillende areas. Die lae groeivlakke soos waargeneem sedert 1987 duur voort wat aandui dat die faktore wat ‘n lae groeitempo veroorsaak, nog steeds teenwoordig is. Resultate bevestig ook seisoenale reserwe opeenhoping in manlike hepatopankreas ter voorbereiding vir die groei (dop verwerp) fase. In teenstelling hiermee, is geen seisoenale opeenhoping in die vroulike hepatopankreas waargeneem nie. Jaar tot jaar variasie in die omvang sowel as tydsintervalle van reserwe opeenhoping is in beide geslagte waargeneem. Gedurende die groeifase, is die opeenhoping van lipiede sowel as proteïene in manlike hepatopankreas sowel as vroulike eierstokke waargeneem. Geen opeenhoping is waargeneem in vroulike hepatopankreas nie. Gedurende die ovariale siklus vind reserwe opeenhoping plaas in die eierstokke, maar nie in die vroulike hepatopankreas nie. ‘n Mate van betrokkenheid van die vroulike abdominale spier is waargeneem in voortplanting (rypwording van die eierstokke). Die vroulike abdominale spier is tot 8% groter as by die manlike kreef, en die grootte neem af soos wat die ovariumsiklus vorder. Tydens die ovariumsiklus was die lipiedvlakke by vroulike krewe in die Houtbaai area (totaal in hepatopankreas sowel as eierstokke), 42 – 120% hoër as by manlike krewe. Die hoër vlakke by die vroulike krewe, beteken, a) hoër tempo van voedselopname, b) genoegsame nutriënte in die area om groei sowel as voortplanting te ondersteun, c) surplus voeding vir manlike krewe beskikbaar om optimale somatiese groei te bevorder. Ter afsluiting, blyk dit dat daar minimale noodsaaklikheid is vir die partisie van reserwes tussen ovarium en hepatopankreas by wyfie krewe in die area. Daar was geen verandering in die vetsuurprofiele van mannetjie en wyfie hepatopankreas sowel as eierstokke van die wyfies tydens groei- en voortplantingsiklusse. Die kwaliteit van beskikbare voeding in die area, is waarskynlik onveranderd tydens die opeenhoping van reserwes en is optimaal vir groei en voortplanting. Die doel van die projek was die identifikasie van potensiële voorspellingsmeganismes vir somatiese groei by mannetjie krewe as inset vir die bepaling van jaarlikse vangs limiete. Die voorvereiste vir ‘n potensiële voorspellingsmeganisme is dat daar duidelike seisoenale variasies moet voorkom en daarom is verskeie parameters tydens die studie ondersoek. Daar is egter bevind dat verskeie parameters, soos die groeifase (vervel) sowel as vetsuurprofiele nutteloos was. Drie stelle data is bevind as potensiële toekomstige voorpellingsmeganismes: 1) opeenhoping van lipiede vir groei in manlike hepatopankreas, 2) reserwe opeenhoping vir voortplanting in vroulike geslagskliere en 3) die verskil tussen mannetjie en wyfie krewe in totale beskikbare lipied vlakke. Slegs 1) korreleer goed met ‘n toename in groei gedurende die daaropvolgende dop verwerp fase in die area. Punte 2) en 3) toon goeie potensiaal maar verdere navorsing is nodig. Alhoewel die studie resultate nie robuus genoeg is om gebruik te word vir die voorspelling van getalle nie, is daar voldoende aanvanklike inligting vir die ontwikkeling van ‘n voorspellingsmeganisme vir ‘n toename in groei van die manlike spesie. Die resultate van die projek voorsien ook belangrike inligting vir toekomstige navorsing rakende die bestuur van die Weskus Rotskreef hulpbron.Doctora
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