Judul: Analisis Pengaruh Faktor Cuaca Untuk Prediksi Serangan Organisme Pengganggu Tanaman (OPT) pada Tanaman Bawang
Abstrak: Pest and disease are the main factors which cause low onion productivity in Brebes. The aim of this reasearch was to find out the effect of weather parameter and pest predator toward the intensity of pest attack (Spodoptera exigua, Liriomyza sp dan Thrips tabaci) using Correlation, Stepwise Regression and Principal Component Regresion technique in two regions. The intensity of Spodoptera exigua, Liriomyza sp and Thrips tabaci attack were influenced by various weather variables from at least one of the combined data of Tmax, Tmin, RH and rain , one until three weeks before the attack period. The intensity of the Spodoptera exigua’s attack showed significant positive correlation with the intensity of the attack in the previous week and predator, while Tmax, RH and rain showed significant negative relationship. The intensity of the Liriomyza sp’s attack showed a significant negative correlation with Tmax, Tmin, RH and rain. Thrips tabaci particularly showed significant negative correlation with Tmax and Tmin. The regression result using Stepwise method for predicting the intensity of Spodoptera exigua's pest attack in region 1 (Karangbale and Pamulian) and region 2 (Kedungbokor, Larangan and Sitanggal) based on intensity attack data from previous week, the predator and weather elements showed a high R2 value if it is analyzed for each areas, that are 99,7% and 100% and for Lyriomiza sp with the R2 value are 45,9% and 94,8%. Particularly for Thrips tabaci, attack analysis based on weather element got a good value if both areas are combined, that is 39,6%. Used of the data, though the obtained linear regression equation get high values of R 2 but has not shown the consistency of weather influenced between sites, the weather and other physical factors observed were no different. For each region and each pest’s cases, the affected weather elements are different.
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Judul: Analisis Pengaruh Faktor Iklim Terhadap Tingkat Serangan Hama Wereng Cokelat (Studi Kasus: Kabupaten Karawang)
Abstrak: Brown Planthopper (Nilaparvata lugens Stal) is one of the limiting factors that cause decline in rice production. Based on existing data, the highest level of infestation occurred in 1998 in three areas of West Java, namely Karawang, Subang, and Indramayu at a total of 40.000 ha. The purpose of this study was to determine the effect of climatic elements on the level of infestation by brown planthopper on rice plantation in Karawang Regency. Climatic elements are used as the independent variable (x) and area infested by brown planthopper as the dependent variable (Y). A quadratic regression and multiple regression were used for the analysis. Quadratic regression analysis is used to express the relationship between the area infested and the climatic elements. Multiple linear regression analysis was performed to obtain the relationship of five climatic factors, namely the maximum temperature, minimum temperature, average temperature, humidity, and rainfall as a whole against area infested by brown planthopper. Climatic element that had the most influence was the minimum temperature with the value of the coefficient of determination (R2 = 17.6%) and with the regression equation of LS = - 8276 + Tm 797.6 - 18.69 TM2. The equation obtained from multiple regression analysis was LS = 905 - 28.0 Tr - 0:12 RH + CH 0210, with R2 = 7.2 %. These results suggested that there was a weak relationship between the area of infestation and the climatic elements.
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Judul: Membran Komposit Kitosan-Zeolit untuk Aplikasi Direct Methanol Fuel Cell
Abstrak: Direct methanol fuel cell (DMFC) is a fuel cell that utilize methanol as the fuel source. The electrolyte membrane used in the DMFC system in this research was chitosan-zeolite composite membrane. The composite membrane was synthesized with chitosan-zeolite composition variation of 1:1, 1:2, 1:3, and 2:1. The membranes were analyzed by Fourier transform infrared spectrophotometer (FTIR) and scanning electron microscope, and for the specific gravity. Membrane performances were tested with methanol uptake, methanol permeability, conductivity, and potential difference in the DMFC system. The FTIR spectrum showed no formation of new functional groups inducating that the composite membrane was a result of physical mixing. Morphological analysis showed that the membrane was nonporous. Chitosan-zeolite 1:3 composite membrane had the highest specific gravity and methanol uptake, 1.4226 g/mL and 41.44%, respectively. The highest proton conductivity was showed by the 1:2 chitosanzeolite composite membrane, namely 7.2946× 10-7 S/cm. Based on this research results, chitosan-zeolite composite membrane can be applied in DMFC system.
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