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Ultrafast laser irradiation of spherical nanoparticles: molecular-dynamics results on fragmentation and small-angle scattering
No full textUsing molecular dynamics simulation we study the response of a spherical nanoparticle to a sudden homogeneous energization, such as effected by ultrashort pulse laser irradiation. We consider a Lennard-Jones model system and two different values of the energization. For the smaller one, the sphere expands while a multitude of voids are created inside; the sphere develops finally into an external shell filled with gas and small clusters. For the higher energization, the sphere expands uniformly and no shell structure is formed. An analysis of the pressure generated confirms that in the latter case the pressure is compressive throughout the sphere expansion, while it is temporarily tensile for the lower energization leading to void formation. The final state of both systems shows the fragmentation of the sphere into a multitude of clusters. With increasing fragmentation the cluster distribution becomes shifted to smaller sizes. Simulated small-angle scattering functions of the exploding NP are presented. The distribution of minima allows for an easy determination of the particle size during expansion
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
PENGEMBANGAN MEDIA PEMBELAJARAN BERBASIS MOBILE LEARNING PADA MATERI DINAMIKA ROTASI DAN KESETIMBANGAN BENDA TEGAR DENGAN MENERAPKAN MODEL PROJECT BASED LEARNING
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PENGEMBANGAN BUKU PENGAYAAN PENGETAHUAN “DARI EVOLUSI BINTANG HINGGA GELOMBANG GRAVITASI†UNTUK SISWA SMA
No full textPENGEMBANGAN DESAIN TEROWONGAN ANGIN SIRKUIT TERBUKA DENGAN TIGA VARIASI PANJANG HONEYCOMB MENGGUNAKAN SCREENMESH
No full textDalam penelitian ini telah dibuat sebuah terowongan angin sirkuit terbuka dengan tiga variasi panjang honeycomb menggunakan screenmesh sebagai pengembangan dari desain terowongan angin yang terdapat di Prodi Fisika FMIPA Universitas Negeri Jakarta. Penggunaan tiga variasi panjang honeycomb menggunakan screenmesh diagonal 3 mm bertujuan untuk menghasilkan terowongan angin tipe terbuka dengan turbulensi sekecil mungkin atau laminar melalui variasi panjang honeycomb menggunakan screen mesh. Pada Desain pertama pada Terowongan angin dengan menambahkan screen mesh setelah honeycomb memiliki nilai intensitas turbulensi sebesar I = 0.0242, sedangkan nilai intensitas turbulensi pada terowongan angin desain kedua, yaitu I = 0.0221 pada p = 6 cm dengan screenmesh diagonal 3 mm, I = 0.0218 pada p = 4 cm dengan screenmesh diagonal 3 mm dan I = 0.0289 pada p = 2 cm dengan screenmesh berdiagonal 3 mm. Dari nilai intensitas turbulensi tersebut diketahui bahwa panjang honeycomb menggunakan screenmesh berpengaruh pada kualitas aliran yang dihasilkan terowongan angin, yaitu adanya variasi panjang honeycomb menggunakan screenmesh diagonal ke ukuran yang lebih kecil mampu memperkecil intensitas turbulensinya.
In this research, an open circuit wind tunnel with three long variations of honeycomb using screenmesh was developed from the wind tunnel design in the Physics Study Program, Faculty of Mathematics and Natural Sciences, State University of Jakarta. The use of three variations of honeycomb length using a 3 mm diagonal screenmesh aims to produce open-type wind tunnels with the smallest possible turbulence or laminar through a long variation of honeycomb using screen mesh. The first design on the wind tunnel by adding screen mesh after honeycomb has turbulence intensity value of I = 0.0242, while the turbulence intensity value in the second design wind tunnel, that is I = 0.0221 at p = 6 cm with 3 mm diagonal screenmesh, I = 0.0218 at p = 4 cm with a 3 mm diagonal screenmesh and I = 0.0289 at p = 2 cm with a 3 mm diagonal screen. From the value of turbulence intensity it is known that the length of honeycomb using screenmesh effect on the flow quality generated by wind tunnel, that is the variation of honeycomb length using screen diagonal to smaller size can minimize turbulence intensity
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