Processing and Transmission of Information

Contains reports on six research projects.Purchase Order DDL-B15

Novel Front-end Electronics for Time Projection Chamber Detectors

Este trabajo ha sido realizado en la Organización Europea para la Investigación Nuclear (CERN) y forma parte del proyecto de investigación Europeo para futuros aceleradores lineales (EUDET). En física de partículas existen diferentes categorías de detectores de partículas. El diseño presentado esta centrado en un tipo particular de detector de trayectoria de partículas denominado TPC (Time Projection Chamber) que proporciona una imagen en tres dimensiones de las partículas eléctricamente cargadas que atraviesan su volumen gaseoso. La tesis incluye un estudio de los objetivos para futuros detectores, resumiendo los parámetros que un sistema de adquisición de datos debe cumplir en esos casos. Además, estos requisitos son comparados con los actuales sistemas de lectura utilizados en diferentes detectores TPC. Se concluye que ninguno de los sistemas cumple las restrictivas condiciones. Algunos de los principales objetivos para futuros detectores TPC son un altísimo nivel de integración, incremento del número de canales, electrónica más rápida y muy baja potencia. El principal inconveniente del estado del arte de los sistemas anteriores es la utilización de varios circuitos integrados en la cadena de adquisición. Este hecho hace imposible alcanzar el altísimo nivel de integración requerido para futuros detectores. Además, un aumento del número de canales y frecuencia de muestreo haría incrementar hasta valores no permitidos la potencia utilizada. Y en consecuencia, incrementar la refrigeración necesaria (en caso de ser posible). Una de las novedades presentadas es la integración de toda la cadena de adquisición (filtros analógicos de entrada, conversor analógico-digital (ADC) y procesado de señal digital) en un único circuito integrado en tecnología de 130nm. Este chip es el primero que realiza esta altísima integración para detectores TPC. Por otro lado, se presenta un análisis detallado de los filtros de procesado de señal. Los objetivos más importantes es la reduccióGarcía García, EJ. (2012). Novel Front-end Electronics for Time Projection Chamber Detectors [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16980Palanci

Digital Image Access & Retrieval

The 33th Annual Clinic on Library Applications of Data Processing, held at the University of Illinois at Urbana-Champaign in March of 1996, addressed the theme of "Digital Image Access & Retrieval." The papers from this conference cover a wide range of topics concerning digital imaging technology for visual resource collections. Papers covered three general areas: (1) systems, planning, and implementation; (2) automatic and semi-automatic indexing; and (3) preservation with the bulk of the conference focusing on indexing and retrieval.published or submitted for publicatio

Using contextual information to understand searching and browsing behavior

There is great imbalance in the richness of information on the web and the succinctness and poverty of search requests of web users, making their queries only a partial description of the underlying complex information needs. Finding ways to better leverage contextual information and make search context-aware holds the promise to dramatically improve the search experience of users. We conducted a series of studies to discover, model and utilize contextual information in order to understand and improve users' searching and browsing behavior on the web. Our results capture important aspects of context under the realistic conditions of different online search services, aiming to ensure that our scientific insights and solutions transfer to the operational settings of real world applications

Imaging through obscurants using time-correlated single-photon counting in the short-wave infrared

Single-photon time-of-flight (ToF) light detection and ranging (LiDAR) systems have emerged in recent years as a candidate technology for high-resolution depth imaging in challenging environments, such as long-range imaging and imaging in scattering media. This Thesis investigates the potential of two ToF single-photon depth imaging systems based on the time-correlated single-photon (TCSPC) technique for imaging targets in highly scattering environments. The high sensitivity and picosecond timing resolution afforded by the TCSPC technique offers high-resolution depth profiling of remote targets while maintaining low optical power levels. Both systems comprised a pulsed picosecond laser source with an operating wavelength of 1550 nm, and employed InGaAs/InP SPAD detectors. The main benefits of operating in the shortwave infrared (SWIR) band include improved atmospheric transmission, reduced solar background, as well as increased laser eye-safety thresholds over visible band sensors. Firstly, a monostatic scanning transceiver unit was used in conjunction with a single-element Peltier-cooled InGaAs/InP SPAD detector to attain sub-centimetre resolution three-dimensional images of long-range targets obscured by camouflage netting or in high levels of scattering media. Secondly, a bistatic system, which employed a 32 × 32 pixel format InGaAs/InP SPAD array was used to obtain rapid depth profiles of targets which were flood-illuminated by a higher power pulsed laser source. The performance of this system was assessed in indoor and outdoor scenarios in the presence of obscurants and high ambient background levels. Bespoke image processing algorithms were developed to reconstruct both the depth and intensity images for data with very low signal returns and short data acquisition times, illustrating the practicality of TCSPC-based LiDAR systems for real-time image acquisition in the SWIR wavelength region - even in the photon-starved regime.The Defence Science and Technology Laboratory ( Dstl) National PhD Schem

Pan-genome Search and Storage

Holley G. Pan-genome Search and Storage. Bielefeld: Universität Bielefeld; 2018.High Throughput Sequencing (HTS) technologies are constantly improving and making genome sequencing more affordable. However, HTS sequencers can only produce short overlapping genome fragments that are erroneous and cover the sequenced genomes unevenly. These genome fragments are assembled based on their overlaps to produce larger contiguous sequences. Since de novo genome assembly is computationally intensive, some species have a reference genome used as a guide for assembling genome fragments from the same species or as a basis for comparative genomics methods. Yet, assembling a genome is an error-prone process depending on the quality of the sequencing data and the heuristics used during the assembly. Furthermore, analyses based on a reference are biased towards the reference. Finally, a single reference cannot reflect the dynamics and diversity of a population of genomes. Overcoming these issues requires to move away from the single-genome reference-centric paradigm and take advantage of the multiple sequenced genomes available for each species. For this purpose, pan-genomes were introduced as sets of genomes from different strains of the same species. A pan-genome is represented by a multi-genome index exploiting the similarity and redundancy of the genomes it contains. Still, pan-genomes are more difficult to analyze than single genomes because of the large amount of data to be stored and indexed. Current data structures for pan-genome indexing do not fulfill all requirements for pan-genome analysis. Indeed, these data structures are often immutable while the size of a pan-genome grows constantly with newly sequenced genomes. Frequently, these data structures consider only assemblies as input, while unassembled genome fragments abound in databases. Also, indexing variants and similarities between the genomes of a pan-genome usually requires time and memory consuming algorithms such as sequence alignments. Sometimes, pan-genome analysis tools just assume variants and similarities are provided as input. While data structures already exist for pan-genome indexing, no solution is currently proposed for genome fragment compression in a pan-genome context. Indeed, it is often of interest to transmit and store all genome fragments of a pan-genome. However, HTS-specific compression tools are not dynamic and cannot update a compressed archive of genome fragments with new fragments of a genome without decompression. Hence, those tools are poorly adapted to the transmission and storage of genome fragments in a pan-genome context. In this thesis, we aim to provide scalable solutions for pan-genome indexing and storage. We first address the problem of pan-genome indexing by proposing a new alignment-free, reference-free and incremental data structure that considers genome fragments as well as assemblies in input: the Bloom Filter Trie (BFT). The BFT is a tree data structure representing a colored de Bruijn graph in which k-mers, words of length k from the input genomes, are associated with sets of colors representing the genomes in which they occur. The BFT makes extensive use of Bloom filters to navigate in the tree and optimize the graph traversal. A "bursting" method is employed to perform an efficient path and level compaction of the tree. We show that the BFT outperforms a data structure that has similar features but is based on an approximation of the set of indexed k-mers. Secondly, we address the problem of genome fragments compression in a pan-genome context by proposing a new abstract data structure, the guided de Bruijn graph. It augments the de Bruijn graph with k-mer partitions such that the graph traversal is guided to reconstruct exactly the genome fragments when decompressing. Different techniques are proposed to optimize the storage of fragments in the graph and the partition encoding. We show that the BFT described previously has all features required to index a guided de Bruijn graph and is used in the implementation of our compression method named DARRC. The evaluation of DARRC on a large pan-genome dataset compared to state-of-the-art HTS-specific and general purpose compression tools shows a 30% compression ratio improvement over the second best performing tool of this evaluation

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion