Judul: Model Regresi Logistik Terboboti Geografis (Studi Kasus : Pemodelan Kemiskinan di Provinsi Jawa Timur)
Abstrak: Geographically Weighted Logistic Regression (GWLR) model is locally logistic regression model. The data in this model is assumed following Binomial distribution and the geographical factor is considered. The geographical factor is used to analyze spatial data from nonstationary processes. The basic idea of this model consider the geography or location as the weight in parameter estimation. The parameter estimator is obtained from Iteratively Reweighted Least Square method by giving different weight for different location. Model for determining the poverty level with a global logistic regression was not suitable to be applied in all districts of East Java Province, because it could be a predictor effect on the poverty level in the region but in other regions the predictor is not significant. The data in this research is from National Social Economy Survey 2008. This research will determine the factors that affect the poverty level in the East Java Province using logistic regression model and GWLR model with a weighting adaptive bi-square kernel function. The results showed that the classification accuracy of logistic regression model was 78.90% and the classification accuracy of GWLR model was 89.47%. GWLR model with a weighting adaptive bi-square kernel function was better than logistic regression model because it had the high classification accuracy and small AIC value.
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Judul: Model Regresi Terboboti Geografis dengan Pembobot Kernel Normal dan Kernel Kuadrat Ganda untuk Data Kemiskinan (Kasus 35 Desa atau Kelurahan di Kabupaten Jember)
Abstrak: Detection of the rural poverty, usually using the average expenditure per capita with a global analysis and the results are applied to all villages. But poverty is very likely influenced by region (space) and neighborhood, so the data between observation difficult to take independent. Geographically Weighted Regression (GWR) is an analysis to accommodate the spatial by involving geographical weighted, which is weighted geographically. Observations on the location of more weight with a smaller weight, according to Tobler's first law of geography which states that the location near the effect will be even greater. In this paper, the weighting used for the GWR model is Gaussian kernel function and bi-square kernel, with their each bandwidth values respectively. Optimal bandwidth can be obtained by minimizing the value of cross validation coefficient (CV). The results showed that the GWR model is more effective than the global regression. According to the mean square error (MSE) values, Gaussian kernel function is better than bi-square kernel as GWR weighting to analyze the data on average expenditure per capita of 35 villages in Jember Regency.
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Judul: Nanokristalin Pirit (FeS2) sebagai Material Semikonduktor Fotovoltaik.
Abstrak: Teknologi fotovoltaik adalah suatu proses yang dapat mengubah sinar matahari menjadi energi listrik dengan media semikonduktor. Penggunaan sel surya untuk fotovoltaik hanya dapat mengonversi radiasi matahari menjadi energi listrik kurang dari 20%. Efisiensi akan meningkat ketika material semikonduktor untuk fotovoltaik dibuat menjadi ukuran nano. Pirit merupakan salah satu material semikonduktor fotovoltaik yang memiliki energi pita celah (Eg) dalam kisaran 0.8–0.95 eV. Energi pita celah tersebut terbukti meningkat ketika disintesis dengan metode hidrotermal menggunakan beragam molar [S]:[Fe] pada suhu 200 °C dalam 24 jam. Nilai energi pita celah yang dihasilkan adalah 1.58–2.073 eV. Ukuran nanokristalin pirit yang dihasilkan berada pada kisaran 21.04–58.77 nm menurut data Particle Size Analyzer. Besarnya ukuran nanokristal pirit yang tumbuh kurang dari 50 nm merupakan poin penting untuk aplikasi fotovoltaik.
Keyword: Hidrotermal, fotovoltaik, nanokristal, pirit