1,720,956 research outputs found
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
Deteksi Dan Implementasi Arcing Tegangan Rendah Pada Sistem Photovoltaic Berdasarkan Transformasi Wavelet
No full textRenewable Energy yang berkembang masif mengharuskan adanya peningkatan dalam proteksi sistem Microgrid DC. Photovoltaic sangat masif berkembang karena harganya yang relatif sudah murah. Salah satu yang bisa menyebabkan sistem DC terutama PV rusak adalah adanya fenomena arcing. Arcing biasanya terjadi dalam waktu singkat, sehingga peralatan MCB dan fuse tidak dapat mendeteksi. Arcing seri sangat sulit dideteksi karena arus gangguan yang lebih kecil dari kondisi normal sehingga menyebabkan MCB dan fuse tidak mendeteksi penurunan arus sebagai adanya gangguan. Pada studi dilakukan pendeteksian Arcing menggunakan mikrokontroler berbasis Discrete Wavelet Transform (DWT). Center of Gravity dan Diagram radar digunakan untuk menentukan jenis wavelet terbaik dalam mendeteksi Series Arc Faults (SAF). Studi ini menggunakan empat jenis wavelet yaitu Haar, Db4, Symplet 4, dan Coiflet 4 dan menggunakan pemanjangan kabel 50M untuk mengetahui pengaruhnya. Algoritma mikrokontroler yang digunakan untuk mendeteksi arcing adalah mengambil arus setiap 700ms dengan 2048 sampel yang masuk ke mikrokontroller STM32F4 sebagai alat teknik pemrosesan sinyal arus dengan mempertimbangkan treshold transformasi wavelet. Ketika sampel yang dideteksi melebihi treshold dari 30 ADC sebagai treshold mengindikasikan adanya arcing. Hasil dari penelitian performa terbaik dalam pendeteksian berbasis mikrokontroler berurutan adalah Db4, Haar, Symplet 4, dan Coiflet 4. Pada beban 1300W dengan Daubechies 4, jarak CoG turun dari 0,423 menjadi 0,319 ketika kabel berukuran 50 meter. Fenomena busur api seri memiliki dua bagian utama yaitu inisiasi arcing dan steady state arcing. Pengujian Center of Gravity (CoG) memiliki hasil wavelet terbaik berurutan yaitu Db4, Haar, Symplet 4, dan Coiflet 4. Luas Area diagram radar memiliki hasil terbaik berurutan adalah Db4, Haar, Symplet 4, dan Coiflet 4. Dimana Daubechies 4 kembali menjadi yang paling terdampak akibat pemanjangan kabel 50M, dengan penurunan hingga 56,8% (dari 0,236 menjadi 0,102 pada 1300W).
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The significant expansion of renewable energy necessitates enhancements in the safeguarding of DC microgrid systems. The rapid proliferation of photovoltaic systems can be attributed to their relatively low costs. A primary factor contributing to the damage of DC systems, especially photovoltaic systems, is arcing. This phenomenon typically occurs within a very brief timeframe, complicating the detection efforts of miniature circuit breakers (MCBs) and fuses. Series arcing poses particular detection challenges, as the fault current is lower than the normal operating current, leading to the failure of MCBs and fuses to recognize the current drop as a fault. In this research, arcing detection was executed using a microcontroller that employs the Discrete Wavelet Transform (DWT). The study utilized center of gravity and radar diagrams to identify the optimal wavelet type for detecting Series Arc Faults (SAF). Four wavelet types were examined: Haar, Db4, Symplet 4, and Coiflet 4, with a 50-meter cable extension to evaluate their impacts. The algorithm implemented in the microcontroller for arc detection involved sampling the current every 700 milliseconds, with 2048 samples processed by the STM32F4 microcontroller as a tool for current signal processing, taking into account the wavelet transformation threshold. An arc was indicated when the detected sample surpassed the threshold of 30 ADC. The sequential detection performance results indicated that Db4, Haar, Symplet 4, and Coiflet 4 yielded the best outcomes. At a load of 1300 W with Daubechies 4, the Center of Gravity (CoG) distance reduced from 0.423 to 0.319 with a cable length of 50 meters. The serial arc phenomenon consists of two primary components: arc initiation and steady-state arcing. The CoG test produced the most favorable wavelet results in the following order: Db4, Haar, Symplet 4, and Coiflet 4. The radar area diagram results corroborated the sequential findings for Db4, Haar, Symplet 4, and Coiflet 4. Daubechies 4 was notably impacted by the increase in cable length, exhibiting a decrease of up to 56.8% (from 0.236 to 0.102 at 1300 W)
Karakteristik Arus Bocor Pada Lembar Isolator Polimer Akibat Pengaruh Jenis Kontaminan
No full textPada studi ini dipelajari karakteristik arus bocor pada lembar isolator polimer akibat kontaminan. Variasi kontaminan yang digunakan adalah kontaminan garam, fly ash, dan alga yang sesuai dengan standar IEC 60815. Untuk kontaminan alga akan dilakukan pengkondisian selama tiga bulan. Pengujian dilakukan menggunakan tegangan tinggi AC yang bervariasi. Pengujian dilakukan mengamati karakteristik arus bocor lembar isolator polimer akibat kontaminan menggunakan osiloskop dengan dibantu oleh circuit pendeteksi PD. Data hasil dari osiloskop akan diolah menjadi data PRPD. Data karakteristik arus bocor hasil pengolahan metode PRPD digambar dengan persebaran pulsa PD. Pengukuran dilakukan menggunakan rangkaian HFCT dan HPF. Variasi yang dilakukan adalah nilai ESDD, NSDD, dan tegangan. Hasil pengujian bahwa kontaminan memberikan dampak yang signifikan terhadap karakteristik arus bocor. Pengujian arus bocor memiliki hasil yaitu kondisi tanpa kontaminan nilai PDIV sebesar 9,95 kV, fly ash tertinggi 21,60 kV Alga tertinggi 14,1 kV, dan garam tertinggi 7,85 kV. Nilai arus bocor dan karakteristiknya akan dipengaruhi jenis kontaminan dilihat dari bahan dan sifatnya. Semakin tinggi nilai ESDD dan NSDD nilai arus bocor yang ditandai dengan munculnya PDIV akan ikut naik. Nilai ESDD dan NSDD akan berbanding lurus dengan besar arus bocor. Jenis kontaminan memiliki karakteristik dan grafik radar yang selalu sama pada setiap jenis kontaminan. Dimana pola grafik ketika normal grafiknya rata keseluruh sisi grafik radar, kontaminan garam rata keseluruh sisi dengan grafik yang paling besar, kontaminan alga rendah di bagian median serta maksimal, dan fly ash rendah pada bagian median serta maksimal.
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This study investigated the characteristics of leakage current in polymer insulator sheets caused by contaminants. The study followed the guidelines of IEC 60815 standards and utilized various contaminants, including salt, fly ash, and algae. Conditioning for algae contaminants was conducted over three months. Tests were performed using varying high AC voltages, and an oscilloscope assisted by a PD detection circuit was used to observe the leakage current characteristics of polymer insulator sheets due to contaminants. The data obtained from the oscilloscope was processed into PRPD data. Leakage and current characteristic data derived from the PRPD method were represented through the distribution of PD pulses. Measurements were conducted using HFCT and HPF circuits, with ESDD, NSDD, and voltage values variations. The test results demonstrated that contaminants significantly impact the leakage current characteristics. The leakage current test yielded a PDIV-free condition of 9.95 kV, with the highest values observed for fly ash (21.60 kV), algae (14.1 kV), and salt (7.85 kV). The leakage current and its characteristics are influenced by the type of contaminant, considering the material and its properties. Higher ESDD and NSDD values correspond to increased leakage current, indicated by the occurrence of PDIV. The ESDD and NSDD values correlate directly with the leakage current. Each type of contaminant possesses unique characteristics and radar charts. The radar chart for normal conditions is flat on all sides, while salt contaminants show a flat pattern on all sides with the largest graph. Small algae contaminants appear on the median and maximum, while low fly ash contaminants are observed on the median and maximum points
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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