Judul: Variation in Natural Durability of Surian (Toona sinensis Roem.) Wood from a Single Tree
Abstrak: Surian (Toona sinensis) merupakan salah satu pohon cepat tumbuh yang banyak ditemukan di Indonesia. Kayunya sudah dijadikan komponen perahu, rumah dan meubel meski baru diperdagangkan secara lokal. Variasi keawetan alami kayu surian masih belum banyak diketahui. Penelitian ini bertujuan mempelajari variasi vertikal dan variasi radial keawetan alami kayu surian dalam satu batang pohon untuk menentukan tindakan pengawetan yang harus diambil dalam rangka pemanfaatan kayu secara maksimal. Contoh uji berupa kayu surian yang mewakili bagian pangkal-tengah-ujung (variasi vertikal atau faktor ketinggian) dan gubal peralihan-teras (cariasi radial atau faktor kedalaman) dalam batang. Sebagai pembanding digunakan kayu pinus. Keawetan alami dievaluasi berdasarkan kehilangan berat dan kerusakan contoh uji setelah dikubur 3 bulan. Hasil penelitian menunjukkan keawetan alami kayu bervariasi menurut ketinggian dan kedalaman batang. Keawetan alami cenderung berkurang dari pangkal ke ujung batang mau pun dari teras ke gubal. Kehilangan berat dipengaruhi oleh faktor ketinggian dan kedalaman, sedangkan kerusakan contoh uji dipengaruhi oleh faktor ketinggian, kedalaman dan interaksi keduanya. Keawetan alami kayu surian secara keseluruhan lebih baik dibandingkan kayu pinus., Surian (Toona sinensis) is one of the fast-growing tree species found in Indonesia. The wood is already used locally as a component for boats, houses and furniture. Since variations in natural durability of this wood are still limited, it is necesary to conduct a study on this aspect. This study aims to investigate variations in natural durability of surian wood, especially from a single tree, both vertical and radial directions in order to determine proper preservative treatment. The test sample was surian wood which represents the bottom-middle-tip as well as the heartwood transition-sapwood. As a comparison, pine wood was utilized. Natural durability of wood was evaluated based on weight loss and damage percentage in cross-section of wood samples after being buried for 3 months. Results showed that natural durability of this wood varies in vertical and radial directions. It tends to decrease from the bottom to the tip of the trunk and from pith (heartwood) to the bark (sapwood). The weight loss percentage was influenced by the height and depth factors, while the damage was influenced by the height, depth and the interaction of these two factors. Overall, natural durability of surian wood is better than that of pine wood.
Keyword: natural durability, pine, radial variation, surian, Toona sinensis, vertical variation

Judul: Variasi Sifat Mekanis Kayu Surian (Toona sinensis Roem.) Dalam Sebatang Pohon
Abstrak: Surian (T. sinensis) adalah salah satu jenis kayu yang berpotensi untuk dijadikan bahan baku industri. Sayangnya, informasi tentang variasi sifat mekanisnya masih sangat terbatas. Penelitian ini bertujuan untuk mengkaji variasi vertikal dan variasi radial beberapa sifat mekanis kayu surian dalam sebatang pohon. Kayu contoh berasal dari pohon surian yang tumbuh sehat di kebun masyarakat di Provinsi Sumatera Barat. Keteguhan lentur statis (MOE dan MOR), keteguhan tekan sejajar serat (σtk//) dan kekerasan kayu kondisi kering udara diukur dengan mengacu kepada BS-373:1957. Hasil penelitian menunjukkan MOE dan MOR tidak bervariasi menurut faktor ketinggian (pangkal-tengah-ujung) mau pun kedalaman (teras-peralihan-gubal), namun kekerasan tangensialnya dipengaruhi oleh inter-aksi kedua faktor. Nilai σtk// dan kekerasan radial hanya dipengaruhi oleh faktor ketinggian. Rata-rata MOE dan MOR berturut-turut adalah 80.626,29 dan 766,65 kg cm-2, rata-rata σtk//nya 331,42 kg cm-2 (pangkal), 375,85 kg cm-2 (tengah) dan 374,41 kg cm-2 (ujung), sedangkan kekerasan radial di pangkal, tengah dan ujung batang masing-masing adalah 358,82, 407,39 dan 488,51 kg cm-2. Kekerasan tangensial kayu teras, peralihan, dan gubal di pangkal dan tengah batang tidak berbeda, namun mereka berbeda dengan yang di ujung batang. Kekerasan tangensial berkisar 339,08 hingga 572,24 kg cm-². Kayu hasil penelitian masuk dalam kelas kuat II‒III.
Keyword: heartwood, mechanical properties, sapwood, surian, transition zone.

Judul: Model Input-output dalam Masalah Network Flow
Abstrak: Production process is a process, which is done by industry, to transform input into output. According to the type of output and its activity, industry can be classified into various sectors, which are connected to each other. Therefore, a model to analyze the connection among sections is needed. The model is known as input-output model (IO model). IO model presents an IO table, which shows informations about the transaction between goods and services in each economic sector. Furthermore, the IO model also shows that the amount of all input is the same as the amount of all output. In this paper, the transaction of each economic sector in IO table is analyzed using network flow theory. The formulated network flow problem implies that each sector represents partly as a producer and also as a consumer. This paper also solves a minimum cost circulation problem.
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