1,720,959 research outputs found
X-band Slotted Waveguide Antenna
No full textA planar slot array antenna of 12x16 elements is designed at X-band with uniform aperture distribution to get maximum aperture efficiency. The antenna is centre fed from iris coupling slot with alternate slot inclinations to feed
the radiating waveguides in phase. A feeding network of nonstandard waveguides is formed to couple the power from feeding network to radiating aperture. A radiating aperture also of non-standard size is selected to give the low profile antenna at 9.65GHz. The longitudinal shunt slots are used with alternate offsets directions to radiate in phase at boresight
A Novel Signal Processing Technique for Ku-Band Automobile FMCW Fully Polarimetric SAR System Using Triangular LFM
No full textThis article presents a novel signal technique for Ku-band automobile frequency-modulated continuous-wave fully polarimetric synthetic aperture radar (FMCW PolSAR) system using triangular linear frequency modulation (LFM). Our proposed system shows the first utilizations of triangular LFM for an FMCW PolSAR. The proposed signal processing algorithm is based on the range Doppler algorithm (RDA). We developed an FMCW PolSAR system that transmits triangular LFM signals, which are used less frequently than sawtooth LFM in an SAR sensor. Using a theoretical background, we describe its configuration and how it works. We propose the novel processing solution, which forms two kinds of single-polarization images from a raw data set and is suitable for our system. We obtained all four kinds of single-polarization images from two raw data sets while using the triangular LFM. In comparison, when using sawtooth LFM, we obtained the four images from four raw data sets by repeating the RDA four times. The proposed method simplifies the FMCW PolSAR system configuration and the processing algorithm. We collected FMCW PolSAR raw data from an experimentally equipped automobile while maintaining a constant speed on a highway. The proposed algorithm and system were validated by processing a high-resolution FMCW PolSAR image.
SAR 애플리케이션을위한 광대역 X / ka 대역 안테나
No full text학위논문(박사) - 한국과학기술원 : 전기및전자공학부, 2020.2,[vi, 54 p. :]In this thesis detail design of microwave components and antenna is presented which were designed for SAR and radar project. A novel rotary joint for drone radar is presented. The rotary joint was used for interface between antenna and transceiver. The antenna and transceiver both had WR-75 interface and a rotary joint using multiple transitions from assymetric mode to symmetric mode is designed and presented. A symmetric mode TM\textsubscript{01} is used in centre waveguide which also includes the joint with a ball bearing mechanism. The problem of discontinuity for joint was solved with matching the length of slot at discontinuity to avoid impedance mismatching.
A gaussian antenna for air borne SAR application with very low sidelobes used in ViSAR is also given. The antenna was designed using hyperbolic and gaussian profiles and the mode content at apertures was adjusted to achieve low sidelobe and cross polarisation. The antennas used a corrugated surface with slot depth of /4 to achieve balanced hybrid condition in the profile and a transition of /2-/4 in the transition region for better impedance matching.
A slotted waveguide array for SAR applications is given using infinite periodic boundary model. A resonant slot array with centre inclined slots is used to feed the radiating aperture comprising of 12x16 antenna elements. Uniform aperture distribution is taken with centre inclined slots for maximum aperture efficiency. In addition to that a travelling wave slot array with progressive phase difference with is also presented. A feeding network with a ferrite switch and a combination of hybrids and power dividers is presented.
An axially displaced ka-band reflector antenna is designed with no blockage from subreflector with a self supported feed system. A potter horn is designed with very low sidelobes is used to illuminate the sub reflector.한국과학기술원 :전기및전자공학부
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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