1,721,008 research outputs found
Daya Tahan Lapisan Finishing Interior Pelarut Air pada Kayu Jati, Kamper, dan Pinus.
No full textThe limited supply of wood from natural forests makes markets interest to wood from plantation forest increase. However, the wood comes from plantation forests considered to be low in quality, including durability. Finishing is one of the solutions to overcome these problems. In this present day there has been developing water based finishing materials (waterbased finishes) that is safe for the environment and does not contain harmful chemicals that can threaten human health. A study has been conducted to determine the durability of the water based finishing layer (Impra Aqua and Sayerlack Waterborne) on Teak (Tectona grandis), Camphor (Dryobalanops aromatica), and Pine (Pinus merkusii). The type of testing conducted covers on the hot and cold test, resistance to household chemical materials, and cross-cut test. The test results showed that the finishing layer is resistant to the hot and cold test, thus can be classified into class 10 (with a completely unblemished surface). The Layer formed by Impra Aqua finishing material is also resistant to all household chemicals tested, so it is classified into class 10. Meanwhile the layer resistance of Sayerlack Waterborne finishing against ballpoint ink tend to be less powerful, so it is classified into class 9, but the finishing materials is resistant to chemicals such as Povidone-iodine. In the test results of paint adhesion (cross cut test), teak wood in wet conditions coated with both types of finishing materials has the weakest adhesion strength, so it is classified into class 3B. Meanwhile, finishing layer for all the wood samples under dry conditions have very strong adhesion, so it is classified in class 5B
Karakteristik Kayu Jati Biotrop Arah Aksial dan Radial
No full textKayu Jati (Tectona grandis Linn F) merupakan salah satu bahan baku
industri perkayuan yang sangat diminati. Peningkatan permintaan kayu jati
mencapai 13-17% per tahun. Oleh karena itu, saat ini sedang maraknya
perkembangan jati cepat tumbuh sebagai solusi untuk mengatasi permasalahan
tersebut. Salah satu jenis jati cepat tumbuh adalah jati biotrop (Tectona grandis
variasi Biotrop). Karakteristik kayu jati biotrop hasil budidaya kultur jaringan
masih belum diketahui oleh masyarakat. Penelitian ini bertujuan untuk
mengetahui karakteristik arah aksial dan radial terhadap sifat dasar kayu jati
biotropika umur 8 tahun.
Pengujian sifat fisis meliputi kadar air, kerapatan, dan berat jenis. Sifat
mekanis meliputi MOE, MOR, dan kekerasan. Pengujian keawetan kayu
menggunakan uji keawetan kayu terhadap rayap kayu kering dan graveyard.
Pengujian sifat kimia dengan menganalisis kadar ekstraktif dan komponen kimia.
Berdasarkan hasil penelitian, sifat dasar kayu baik sifat fisis, mekanis, keawetan
alami kayu, dan kimia menunjukkan adanya variasi pada arah aksial dan radial
Pengaruh Cuaca terhadap Daya Tahan Lapisan Finishing Eksterior Berpelarut Air pada Kayu Kamper, Jati, dan Pinus
No full textPenggunaan kayu sebagai bahan kontruksi belum dapat tergantikan oleh bahan
lain. Pengaruh lingkungan, biologis, dan non-biologis dapat menyebabkan kayu
terdegradasi. Finishing merupakan solusi untuk mengatasi masalah tersebut. Tujuan
penelitian ini adalah (1) menentukan daya tahan lapisan finishing eksterior berpelarut
air Ultran Aqua Politur (UAP) dan Sayerlack terhadap pengaruh cuaca terbuka pada
kayu kamper, jati, dan pinus berpenampang radial dan tangensial pada kondisi basah
(KA 25-30 %) dan kering (KA 10-15 %) serta (2) isolasi dan identifikasi cendawan
yang tumbuh pada contoh uji. Contoh uji dibuat dengan ukuran 20 cm x 10 cm x 2 cm
yang kemudian diampelas dan dilaburi bahan finishing eksterior berpelarut air UAP
dan Sayerlack. Setelah itu, contoh uji dipaparkan selama 36 bulan di ruang terbuka dan
diamati perubahannya berdasarkan tingkat kerusakan terhadap cacat checking, cacat
cracking, dan cacat serangan mikroba. Hasil penelitian menunjukkan bahwa lapisan
finishing eksterior dengan pelarut air pada kayu kamper, jati, dan pinus yang
dipaparkan selama 36 bulan menunjukkan penurunan rating yang berarti. Lapisan
finishing UAP memberikan daya tahan yang lebih baik dibandingkan daya tahan
lapisan finishing Sayerlack. Aplikasi finishing UAP pada kayu jati penampang radial
dengan kondisi kering memberikan daya tahan yang paling baik. Cendawan yang
ditumbuh pada contoh uji ada tujuh yaitu Dacriophinac sphatularia, Trichoderma
sp.; Irpex lacteus, Bispora sp.; Mycellia sterilia, Drechslera sp.; dan Pycnoporus
sp.
Karakteristik Modifikasi Panas pada Kayu Jati Rotasi Pendek dan Panjang dan Pengaruhnya terhadap Cuaca
No full textKayu jati adalah salah satu jenis kayu tropis yang terkenal. Kayu ini memiliki
stabilitas dimensi yang tinggi, tahan terhadap jamur, dan memiliki gambar yang
indah. Saat ini, ketersediaan kayu jati rotasi panjang mulai terbatas, sedangkan
permintaan terhadap kayu tersebut meningkat. Hal tersebut mendorong industri
kayu untuk mencari pengganti kayu jati berotasi panjang. Lembaga penelitian
seperti LIPI dan Litbang Perhutani sudah mengembangkan kayu jati berotasi
pendek. Hal ini dilakukan sebagai upaya untuk mengatasi keterbatasan kayu jati
berotasi panjang. Kayu jati rotasi pendek yang mempunyai masa tebang relatif
pendek sekitar 7-10 tahun cenderung bersifat kurang stabil dimensinya dan
ketahanan alaminya rendah. Salah satu metode peningkatan mutu kayu yang ramah
lingkungan yaitu pemanasan pada suhu tinggi. Tujuan dari penelitian ini adalah
untuk menginvestigasi efek dari pemanasan pada suhu 220 °C selama 20 jam
dibawah gas nitrogen terhadap komposisi kimia, antioksidan, stabilitas dimensi,
ketahanan terhadap serangan jamur, dan untuk menganalisis efek ketahanan kayu
jati terhadap pengaruh cuaca buatan.
Pada penelitian ini, kayu dipanaskan pada suhu 220 °C selama 20 jam pada
kondisi gas nitrogen. Hasil penelitian menunjukkan bahwa kayu jati mengalami
degradasi hemiselulosa dan peningkatan persentase relatif selulosa dan lignin
setelah pemanasan. Kadar ekstraktif pada kayu jati berotasi pendek mempunyai
nilai yang lebih rendah dibanding jati berotasi panjang. Proses pemanasan pada
kayu jati menyebabkan penurunan kadar ektraktifnya. Ektrak jati yang dipanasan
menghasilkan aktifitas antioksidan yang lebih efektif. Peningkatan stabilitas
dimensi ditandai dengan nilai anti-swelling efficiency sebesar 64.87% untuk jati
rotasi pendek dan 58.93% untuk jati rotasi panjang. Ketahanan terhadap jamur
Trametes versicolor meningkat pada jati yang dipanaskan. Pengecatan pada
permukaan jati yang dipanaskan menghasilkan kekuatan pelekatan dan
fotostabilitas yang lebih baik dibandingkan dengan tanpa pemanasan. Jati berotasi
pendek yang dipanaskan dapat dipertimbangkan untuk penggunaan eksterior
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
Lathe Check Characteristics of Fast Growing Sengon Veneers and Their Effect on LVL Glue-Bond and Bending Strength
Full text linkFast growing sengon (Paraserianthes moluccana) is largely rotary-cut to produce veneer for core plywood production. In order to provide better information on veneer production and utilization, in this study the effects of wood juvenility and veneer thickness on lathe checks of rotary-cut sengon veneers were evaluated. Before veneer manufacturing, sengon logs were boiled at 50 oC and 75 oC for 4 and 8 hours respectively. The boiled logs were peeled to produce veneer of 1 mm, 1.5 mm, 2 mm in thickness. Lathe checks of veneers were measured on the loosed side at every 5 mm veneer length under an optical video microscope and their frequency, depth, and length were characterized. Twenty sampling points of 5 mm veneer length were prepared from each segmented ring of 1 cm width from pith to bark. Isocyanate resin adhesive were used to produce laminated veneer lumber (LVL) of 20 mm thick, which consisted of 24-ply of 1 mm veneer thick, 14-ply of 1.5 mm veneer thick, and 11-ply of 2 mm veneer thick, for glue bond and bending strength test. Results showed that wood juvenility and veneer thickness determined the frequency, depth and length of lathe checks for the sengon rotary-cut veneers. In general, the frequency of lathe checks of the veneer increases with increasing veneer thickness, and also increases from pith to bark. Boiling of logs before rotary-cutting could decreases the frequency of lathe check of the veneer. The results indicated that boiling of logs at 50 oC for 8 h and at 75 oC at least 4 h before peeling the logs could minimize the frequency of lathe check in manufacturing rotary cut veneer thickness of 1 mm, 1.5 mm, and 2 mm from juvenile wood of fast growing sengon. The frequency of lathe check affect significantly the glue bond and bending strength, in which the glue bond, Modulus of Elasticity (MOE), and Modulus of Rupture (MOR) decrease as the frequency of lathe checks increases.The authors thank the Directorate for Research and Community Service of the Ministry of National Education for the Republic of Indonesia for the research gran
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