Judul: Characterization of Natural Rubber Coagulum Quality by Ultrasonic Method
Abstrak: Raw rubber is prepared mostly in the the form of coagulum by the small holders. Its quality is commonly judged subjectively by visual measure to determine the dry rubber content, moisture content and foreign materials. Ultrasonic method, as a non-destructive objective alternative, may be considered for the evaluation of coagulum quality. The objectives of this research were to assess the relationship of coagulum quality with the rubber elasticity and the properties of ultrasonic wave, to develop the mathematical model to relate the coagulum quality with the acoustic characteristics, and to apply neural network in determining dry rubber content. Test samples were based on model, made by coagulating fresh latex with formic acid and the addition of foreign materials. The foreign materials were limited to sand, rubber wood shavings, and their mixture. The result showed that increasing moisture content of 18-43% caused the increasing density, decreasing Young modulus, as well as decreasing attenuation and wave velocity. The increasing of sand up to 20% caused the increasing of density from 930 to 1014 kg m-3, the Young modulus from 0.295 to 1.12 MPa, the attenuation from 504 to 1520 dB m-1, and the decreasing of wave velocity from 1516 m s-1 to 1441 m s-1. The increasing of wood shavings up to 20% caused the increasing of wave velocity from 1481 to 1545 m s-1, the attenuation from 504 to 1,108 dBm-1, and the decreasing of density from 975 to 869 kg m-3., Bahan olah karet sebagian besar terbentuk koagulum dan berasal dari perkebunan rakyat. Penilaian mutunya secara umum dilakukan subyektif melalui pengamatan visual untuk penentuan kader karet kering, kadar air dan kadar kotoran. Metode ultrasonic, sebagai metode yang bersifat obyektif dan tidak merusak, diharapkan dapat dijadikan metode alternative untuk evaluasi mutu koagulum.
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Judul: Pembuatan Karet Remah Dari Campuran "Latex", "Unsmoked Sheets", Field Coagulum" dan Minyak Pelunak
Abstrak: Tujuan penelitian ini adalah guna mengetahui kemung kinan pembuatan karet ideal untuk ban (Ideal tyre rubber) dengan menggunakan karet remah dari campuran latek, "ung moked sheets", "field coagulum" yang ada di Indonesia dan minyak pelunak. Sebagai perlakuan dalam percobaan ini yaitu pertama pengaruh campuran bahan karet (dalam persen kadar karet kering) antara latek dengan komposisi 30 persen, "unsmo- ked sheets" dangan komposisi O persen, 10 persen, 20 per. sen, 30 persen, 40 persen, 50 persen, "field coagulum" "slab" dengan komposisi 0 persen, 10 persen, 20 persen, 30 persen, 40 persen, 50 persen, 60 persen, "scrap" deng an komposisi 0 persen, 10 persen, 20 persen, 30 persen, 40 persen, 50 persen, 60 persen, "alab" + "scrap" dengan komposisi O persen, 10 persen, 20 persen, 30 persen, 40 persen, 50 persen, 60 persen, kedua ingin mengetahui pe- ngaruh minyak pelunak dengan komposisi 0 persen dan 10 persen. Rancangan percobaan yang digunakan adalah ran- cangan acak lengkap dengan 2 ulangan. Pemeriksaan yang dilakukan ilah penentuan aceton ekstrak, viskositas ...
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Judul: Spatiotemporal Data Model Development on Hotspot Data with an Event-based Spatiotemporal Data Model (ESTDM) Concept
Abstrak: Hotspot data that has been existed all this time is still in the form of usual spatial data which is not enough to keep temporal information and information about how a hotspot evolved. There are so many disadvantages in keeping the hotspot data. Therefore a data model that can keep enough information to represent the hotspot evolution is needed, and also can handle the lack of keeping the previous hotspot data. An Event-based Spatiotemporal Data Model (ESTDM) concept is propose to overcome this problem. Appearance and disappearance process that occurs on hotspot will be used as base for spatiotemporal data model development on hotspot data. This research aims to implement an Event-based Spatiotemporal Data Model (ESTDM) concept into PostgreSQL. As a result, we can get the informations about spatial information and temporal information about geographical information changes to represent hotspot evolution from spatiotemporal query such as show hotspot that reappear after experience disappearance before. These queries make analyze a hotspot easier. The result of these queries can be visualized in a Indonesian map then with histories about period of appearance and disappearance of hotspot.
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