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: Kasus Perkebunan Rakyat di Kecamatan Tulang Bawang Tengah, Kabupaten Tulang Bawang, Lampung
Abstrak: This research compared rubber quality between smallholder rubber farmers in rubber development program village and non-program village. The objectives of the research were to describe the socioeconomic characteristics of the farmers, describe the rubber farm conditions, identify cause of low-quality rubber, identify farmer’s efforts to increase rubber quality, to describe and to test relationship between socioeconomic characteristics of the farmers, technical factors, and rubber quality among them, and to analyze the net increase of farmer income after use of rubber quality improvement technology. Data for the research were generated from 64 respondents randomly (stratified cluster sampling) from three villages; one village was rubber development program village and two else were non-program villages. Descriptive statistics, qualitative analysis and binary logistic regression model were used in analysing the data. The empirical data showed that majority of farmers were over 40 years: 54.69 percent were middle age (40-60 years) and 31.25 percent were old age (over 60 years). Findings revealed that majority of farmers (93.75 percent) cultivated their rubber plantation by intercropping system. The result of analysis showed that smallholder rubber farmers in rubber development program village produced lower grade rubber (average 6.13) than rubber farmers in non-program village (average 6.98). The cause of that was the use of additive coagulant such as extract of Gadung tuber (Dioscorea hispida Dennst). The identification result suggest that the causes of low-quality rubber were the use of coagulant other than formic acid and existence of contaminants such as wood shavings (tatal), leafs and black dry rubber in coagulump. The empirical result revealed that majority of farmers did efforts to increase rubber quality such as cleaning of collecting pans periodic (57,81 percent), keeping of coagulump from contaminants (57,81 percent), but just a little farmer used trained tappers (32,81 percent), cleaning of collecting cups before tapping(28,12 percent ), dissociating types of coagulump (9,38 percent). There were no farmers using of formic acid as coagulant. The qualitative analysis indicated relationship between membership of farmer institution and soscial acivities, education, family income, family size, farm size, use of TSP as coagulant and rubber quality. The binary logistic regression model revealed relationship between age, education (negative relationship), family size, membership of farmer institution, familu size, (positive relationship) and rubber quality at 20 percent probability level. The partial budgets analysis proved that use of formic acid as coagulant was profitable in program village and non-program village, but there were no farmers using of formic acid as coagulant because it was scarce (difficult to find).
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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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