2,239,331 research outputs found
Decoding of Cluster Array Errors in Row-Cyclic Array Codes
No full text[[abstract]]Row-cyclic array codes equipped with m-metric [13] suitable for parallel
channel communication systems have been introduced by the first
author in [10] and the notion of cluster/burst array errors were introduced
by the first author in [6]. In this paper, we study cluster array
errors detection and correction in row-cyclic array codes
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A Brassica exon array for whole-transcript gene expression profiling
No full textAffymetrix GeneChip® arrays are used widely to study transcriptional changes in response to developmental and environmental stimuli. GeneChip® arrays comprise multiple 25-mer oligonucleotide probes per gene and retain certain advantages over direct sequencing. For plants, there are several public GeneChip® arrays whose probes are localised primarily in 3′ exons. Plant whole-transcript (WT) GeneChip® arrays are not yet publicly available, although WT resolution is needed to study complex crop genomes such as Brassica, which are typified by segmental duplications containing paralogous genes and/or allopolyploidy. Available sequence data were sampled from the Brassica A and C genomes, and 142,997 gene models identified. The assembled gene models were then used to establish a comprehensive public WT exon array for transcriptomics studies. The Affymetrix GeneChip® Brassica Exon 1.0 ST Array is a 5 µM feature size array, containing 2.4 million 25-base oligonucleotide probes representing 135,201 gene models, with 15 probes per gene distributed among exons. Discrimination of the gene models was based on an E-value cut-off of 1E−5, with ≤98% sequence identity. The 135 k Brassica Exon Array was validated by quantifying transcriptome differences between leaf and root tissue from a reference Brassica rapa line (R-o-18), and categorisation by Gene Ontologies (GO) based on gene orthology with Arabidopsis thaliana. Technical validation involved comparison of the exon array with a 60-mer array platform using the same starting RNA samples. The 135 k Brassica Exon Array is a robust platform. All data relating to the array design and probe identities are available in the public domain and are curated within the BrassEnsembl genome viewer at http://www.brassica.info/BrassEnsembl/index.html
An investigation of a frequency diverse array
No full textThis thesis presents a novel concept for focusing an antenna beam pattern as a function
of range, time, and angle. In conventional phased arrays, beam steering is achieved by
applying a linear phase progression across the aperture. This thesis shows that by
applying an additional linear frequency shift across the elements, a new term is
generated which results in a scan angle that varies with range in the far-field.
Moreover, the antenna pattern is shown to scan in range and angle as a function of time.
These properties result in more flexible beam scan options for phased array antennas
than traditional phase shifter implementations. The thesis subsequently goes on to
investigate this phenomenon via full scale experimentation, and explores a number of
aspects of applying frequency diversity spatially across array antennas. This new form
of frequency diverse array may have applications to multipath mitigation, where a radio
signal takes two or more routes between the transmitter and receiver due to scattering
from natural and man-made objects. Since the interfering signals arrive from more than
one direction, the range-dependent and auto-scanning properties of the frequency
diverse array beam may be useful to isolate and suppress the interference. The
frequency diverse array may also have applications to wideband array steering, in lieu
of true time delay solutions which are often used to compensate for linear phase
progression with frequency across an array, and to sonar, where the speed of
propagation results in large percentage bandwidth, creating similar wideband array
effects. The frequency diverse array is also a stepping stone to more sophisticated joint
antenna and waveform design for the creation of new radar modes, such as simultaneous
multi-mode operation, for example, enabling joint synthetic aperture radar and ground
moving target indication
Design of high frequency ultrasonic array transducers for medical imaging
No full textUltrasonic transducers have been widely used in the medical applications. High frequency array transducers have recently attracted many research interests, since it provides not only the electronic beamforming but also the very fine image resolution. The transducers are usually either annular or linear arrays. This study concentrates on the design of both types of array in high frequency applications.The annular array is firstly investigated, and an optimized design of array geometry is developed including the kerfs influence which is usually neglected in the design of high frequency arrays. The improved imaging performance is found by this optimized design. More interestingly, the conventional annular array with element having the same surface area has a relatively large sidelobe closest to the main lobe. Two methods are applied to suppress the sidelobe. The method of using high-impedance single matching to enlarge the element bandwidth only shows very limited lobe suppression, however, a novel matching approach is found. Another method of changing the array geometry from equal area elements to equal width ones successfully suppressed the sidelobe. The imaging results suggest that the novel equal width array shows a good improvement.The linear array is then analyzed. The kerfs influence again is found to be significant for the array especially for high frequency. It is essential to use a high attenuated kerfs material in the linear array design. More importantly, the limitation of current fabrication techniques forces the linear array to concede a high grating lobe in the imaging field if it operates in a relatively high frequency. A novel linear array is developed to suppress the grating lobe without using advanced fabrication techniques. The imaging results show that the novel linear array has a general reduction of -6dB for the lobe suppression. The novel design made the linear array operate in a very high frequency without strong grating lobe, and the array can be fabricated by current techniques
Configurable 3D-integrated focal-plane sensor-processor array architecture
No full textA mixed-signal Cellular Visual Microprocessor architecture with digital processors is
described. An ASIC implementation is also demonstrated. The architecture is composed of a
regular sensor readout circuit array, prepared for 3D face-to-face type integration, and one or
several cascaded array of mainly identical (SIMD) processing elements. The individual array
elements derived from the same general HDL description and could be of different in size, aspect
ratio, and computing resources
Design of a Novel High Frequency Ultrasound Annular Array
No full textAbstractThe design of a novel 50MHz 7-elment annular array is described. Equal-width electrodes are deposited on the rear face of piezoelectric layer to form a kerfless array, instead of mechanical cutting. Compared with equal-area designs, much better performance is achieved by the novel design. The cross talk is down to -20dB, the -6dB bandwidth and insertion loss are 41% and 18dB, respectively. The pulse responses are largely improved compared with conventional kerfless annular arrays. Furthermore, no pre-focus lens for the central element is required in this array, promising simplified fabrication
Optimal E-Field Vector Combination for a Highly Focused Antenna-Array
No full textA near-field highly focused circular phased-array antenna for 5.8-GHz radio frequency identification (RFID) applications is presented. The electric field (E-field) at the focus is enhanced by a constructive vector combination in a three-dimensional (3-D) coordinate system. The array dipoles of the antenna are oriented to enhance the energy confinement at the focus, and the radii of the circular array is optimized for lower sidelobe levels. As a result, the proposed design achieves an enhanced focalization of ~4 dB with reduced sidelobe levels of ~12dB compared to earlier designs
CTAO Instrument Response Functions - prod5 version v0.1
No full textCTAO Instrument Response Functions - prod5 version v0.1 The CTA Observatory (CTAO) will provide very wide energy range and excellent angular resolution and sensitivity in comparison to any existing gamma-ray detector. Energies down to 20 GeV will allow CTAO to study the most distant objects. Energies up to 300 TeV will push CTAO beyond the edge of the known electromagnetic spectrum, providing a completely new view of the sky. This data repository provides access to performance evaluation and instrument response functions (IRFs) for CTA. IRF version: prod5 v0.1 Telescope model and site configuration: prod5-model Publication date: Sep 2021 Archived webpage with performance figures included: CTAO Performance Description (file Website.md) Licence: this work is licensed under a Creative Commons Attribution 4.0 International License . Please use the contact address [email protected] for any inquiries. Citation and Acknowledgements: In cases for which the CTA instrument response functions are used in a research project, we ask to add the following acknowledgement in any resulting publication: 'This research has made use of the CTA instrument response functions provided by the CTA Consortium and Observatory, see https://www.ctao-observatory.org/science/cta-performance/ (version prod5 v0.1; [citation]) for more details.' Please use the following BibTex Entry for [citation] in the reference section of your publication: https://zenodo.org/record/5499840/export/hx Description Monte Carlo Simulations: The performance values are derived from detailed Monte Carlo (MC) simulations of the CTA instrument based on the CORSIKA air shower code (v7.71, with the hadronic interaction models QGSjet-II-04 and URQMD, [1]) and telescope simulation tool sim_telarray [2]. A power- law gamma-ray spectrum with photon index 2.62 was assumed in the calculations, although none of the instrument response functions (e.g. differential flux sensitivities, effective areas, angular or energy resolutions) depends on the assumed spectral shape of the gamma-ray source. Background cosmic-ray spectra of proton and electron/positron particle types are modelled according to recent measurements from cosmic-ray instruments. Nominal telescope pointing is assumed, with all telescopes pointing directions parallel to each other (performance estimation for other pointing modes, e.g. divergent pointing will be provided in the future). Performance estimations are available for three zenith angles (20 deg, 40 deg, and 60 deg), and for each zenith angle for two different azimuth angles (corresponding to pointing towards the magnetic North and South). There are significant performance differences found between the two azimuthal pointing directions (especially for the Northern site) as the impact of the geomagnetic field is large enough to influence notably the air shower development. For general studies, the use of the azimuth-averaged instrument response functions is recommended. Instrument Response Functions (IRFs): The analysis has been tuned to maximize the performance in terms of flux sensitivity. The optimal analysis cuts depend on the duration of the observation, therefore the IRFs are provided for 3 different observation times, from 0.5 to 50 h. IRFs are provided as binned histogram or FITS tables. It should be stressed, that the full potential of CTA in terms of angular and energy resolution is not revealed by these IRFS, due to the focus on the optimisation for best flux sensitivity. In general all histograms are binned with a 0.2-binning on the logarithmic energy axis (5 bins per decade); some selected histograms (e.g. effective areas or energy migration matrices) are provided with a finer binning. Effective area and energy migration matrix are available in a double version: one for the case in which there is no a priori knowledge of the true direction of incoming gamma rays (e.g. for the observation of diffuse sources), and another for observations of point-like objects (including among the analysis cuts one on the angle between the true and the reconstructed gamma-ray direction). IRFs are provided in ROOT format and as FITS tables. The FITS tables can be used directly as input to science analysis tools. The values of the IRFs are identical for the different file format, with one exception: the angular point-spread function is approximated by a Gaussian function for the FITS tables, while the ROOT files contain the full distribution. Telescope layouts are preliminary and subject to change. The following array layouts (Alpha configuration) have been assumed: CTA South with 14 MSTs and 37 SSTs (see [figure](figures/CTA-Performance-prod5-v0.1-South-Alpha-Layout.png)) CTA North with 4 LSTs and 9 MSTs (see [figure](figures/CTA-Performance-prod5-v0.1-North-Alpha-Layout.png)) Two zip files are uploaded: full archive with IRFs in FITS and ROOT format: cta-prod5-zenodo-v0.1.zip partial archive with IRFs in FITS format only: cta-prod5-zenodo-fitsonly-v0.1.zip File Naming (examples): Prod5-North-40deg-AverageAz-4LSTs09MSTs.18000s-v0.1.root: IRF for CTA Northern site on La Palma, 40 deg zenith angle, azimuth-averaged pointing, optimised for 5 hours of observation time Prod5-South-20deg-AverageAz-14MSTs37SSTs.180000s-v0.1.fits.gz: IRF for CTA Southern site in Paranal, 20 deg zenith angle, azimuth-averaged pointing, optimised for 50 hours of observation time List of files: FITS format: fits/CTA-Performance-prod5-v0.1-North-20deg.FITS.tar.gz fits/CTA-Performance-prod5-v0.1-North-40deg.FITS.tar.gz fits/CTA-Performance-prod5-v0.1-North-60deg.FITS.tar.gz fits/CTA-Performance-prod5-v0.1-South-20deg.FITS.tar.gz fits/CTA-Performance-prod5-v0.1-South-40deg.FITS.tar.gz fits/CTA-Performance-prod5-v0.1-South-60deg.FITS.tar.gz ROOT format: root/CTA-Performance-prod5-v0.1-North-20deg.tar.gz root/CTA-Performance-prod5-v0.1-North-40deg.tar.gz root/CTA-Performance-prod5-v0.1-North-60deg.tar.gz root/CTA-Performance-prod5-v0.1-South-20deg.tar.gz root/CTA-Performance-prod5-v0.1-South-40deg.tar.gz root/CTA-Performance-prod5-v0.1-South-60deg.tar.gz IRFs for subarrays of e.g., MSTs only are in the files named MSTSubArray (similar for all other telescope types). References [1] https://www.ikp.kit.edu/corsika/ [2] Bernloehr, K. 2008, Astroparticle Physics, 30, 149 Acknowledgements We would like to thank the computing centres that provided resources for the generation of the Prod 5 Instrument Response Functions (IRFs): CAMK, Nicolaus Copernicus Astronomical Center, Warsaw, Poland CIEMAT-LCG2, CIEMAT, Madrid, Spain CYFRONET-LCG2, ACC CYFRONET AGH, Cracow, Poland DESY-ZN, Deutsches Elektronen-Synchrotron, Standort Zeuthen, Germany GRIF, Grille de Recherche d’Ile de France, Paris, France IN2P3-CC, Centre de Calcul de l’IN2P3, Villeurbanne, France IN2P3-CPPM, Centre de Physique des Particules de Marseille, Marseille, France IN2P3-LAPP, Laboratoire d Annecy de Physique des Particules, Annecy, France INFN-FRASCATI, INFN Frascati, Frascati, Italy INFN-T1, CNAF INFN, Bologna, Italy INFN-TORINO, INFN Torino, Torino, Italy MPIK, Heidelberg, Germany OBSPM, Observatoire de Paris Meudon, Paris, France PIC, port d’informacio cientifica, Bellaterra, Spain prague_cesnet_lcg2, CESNET, Prague, Czech Republic praguelcg2, FZU Prague, Prague, Czech Republic UKI-NORTHGRID-LANCS-HEP, Lancaster University, United Kingdo
SENSOR ARRAY ABLE TO DETECT AND RECOGNISE CHEMICAL WARFARE AGENTS
No full textIn this paper we studied a device based on array of six different sensors with surface acoustic wave for detections and recognition of three chemical warfare agents (chloropicrin, soman and lewisite). The sensors are “delay line” type with a center frequency of 69.4 MHz. It presents an original algorithm to identify the nature and concentration of gas from a finite range of possible gases. Numerical program developed to implement this algorithm, provides to operators all the particulars of gas and an indicator of credibility of the results provided as a measure of the degree of disturbance of the signals received from sensors.SAW, chemical warfare agent, array of sensors, algorithm
A new blind adaptive antenna array for GNSS interference cancellation
No full textThis paper introduces a new blind adaptive antenna array as a possible solution to the interference cancellation problem. This new technique is compared to three classical ones over two different sensor radiation patterns. Special attention is paid to the array compatibility with a conventional GNSS receiver. A wide radiation pattern sensor is shown to improve the positioning accuracy by maximizing the satellite constellation visibility. Finally, the new processor demonstrates its superiority in term of positioning accuracy in presence of strong interferences. However, its phase response may make it incompatible with classical GNSS receivers. Some efforts must be done to stabilize it
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