1,720,973 research outputs found
Karakteristik Medan Listrik Atmosfer Kota Padang dan Hubungannya dengan Sambaran Petir Awan ke Tanah
No full textPengukuran Radiasi Elektromagnetik Frekuensi Sangat Tinggi (VHF) Petir Compact Intracloud Discharges
Full text linkCompact Intracloud Discharges (CIDs) are another type of intracloud lightning. CIDs emit strong high-frequency emissions compared to the first return stroke from cloud to ground lightning or other types of discharge in clouds. High-frequency radiation from lightning CIDs may affect electronic systems, which may pose a danger to communications equipment, radio, satellite and avionics systems. This paper presents a design of a fast electric field detector to detect a broadband of radiation from CIDs and Very High Frequency (VHF) electric field detector to detect high-frequency radiation of CIDs. Fast electric field detector circuit consists of buffer circuit and integrator amplifier while VHF electric field detector is a buffer circuit and active band pass filter at 51.76 MHz. From the measurement of the electric field of lightning during March 2016 to March 2017, 104 CID negative lightning data and 33 positive CID lightning data was recorded. VHF radiation of CID is detected simultaneously with the occurrence of CID lightning events. The VHF radiation of negative CID and positive CID have similar time characteristics
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
Sistem Informasi Petir (SIP) dengan Metode Lightning Distribution (LD) di Wilayah Sumatera Barat
No full textThis paper mapped 200 locations of lightning strikes in West Sumatra province. Mapping the location of lightning strikes as part of Lightning Information System was designed with the method of Lightning Distribution (LD). To get the location of lightning strikes obtained from the calculation reflection of ionosphere method to determine the distance of a lightning strike from stations of lightning and methods of Magnetic Direction Finding (MDF) to get directions from the lightning strike. Direction data obtained processed to generate a lightning incident location, then that location will be displayed on Google Maps. After that in the process of Lightning Distribution method which is a form of lightning strike density mapping by using the "File Format" grid, where each grid was measured to be 1 x 1 km2 called the Local Density Flash (LFD). If there are multiple point strikes on the grid will change the color that is on the map fit how many number of strikes on the grid which is a Probabilistic computation Flash Density (PFD). The depiction of the scale of danger lightning in the form of variations color changes at the point where the bolt of green color represents the minimum number density of lightning strikes that contains a single point and the red color represents the maximum number density of strikes which contains more than ten points strike. Based on the color distribution of lightning strikes and Payakumbuh Agam area has the highest rate of lightning strikes in the study period
Sistem Deteksi Petir Multistation Dengan Metode Time of Arrival
No full textThis study was done at ligtning detection system in Padang. The systems was consist of 3 electric field sensors with synchronous satelite GPS. Time of arrival and sensors coordinate was taken from each sensors. This data was used to calculate ligtning location by Time of Arrival Linear Spherical method. Then the distances between lighting and sensor can be calculated. The distances will compared with electric field waveforms recorded at lightning sensor to testing validity our results. After validity, lightning current peak can be calculated. 8 of 20 data sample are valid with lowest lightning current peak is -1,001 kA dan highest value is -2,661 kA
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