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: Application of phycocyanin from microalgae Spirulina platensis as light harvesting in anatase TiO2 nanoparticle solar cell.
Abstrak: The dye sensitized solar cell (DSSC) has been assemblied used hybrid titanium oxide (TiO2) film/phycocyanin. The TiO2 film was synthesized by sol gel method with titanium chlorida (TiCl4) as precursor by hydrolysis used sulfuric acid (H2SO4). Furthermore, it calcinated for 2,5 hours in variation of annealing temperature (400oC, 600oC, 800oC, dan 1000oC). In XRD patterns exhibited which annealing temperature at 400oC to 800oC were anatase phase all. When annealed at temperature 1000oC, it caused phase transformation from anatase to rutile. The crystals size according to XRD patterns were 13,75 nm, 20,79 nm, 25,25 nm, 48,88 nm and particle size from SEM images were 43,06 nm, 44,91 nm dan 64,99 nm, 80,40 nm, respectively. The crystals and particle size increased with annealing temperature. The film thickness influenced material absorption. The optical measurement of TiO2 film and TiO2/phycocyanin hybrid film used UV-Vis spectrophotometer. Additional phycocyanin caused peak width of absorbed region from ultraviolet to visible region. The band gap energy of TiO2 can be calculated using the cut off wavelength obtained from the absorbance spectrum of a nanoparticles TiO2 films. Based on intersection between linear and energy (hv) axis. In this study just limited for anatase phase. It was caused anatase band gap is wider than rutile phase. That’s meaningful for solar cell application such as dye sensitized solar cell (DSSC). The absorption coefficient average at difference annealing temperature such as at 400oC, 600oC, 800oC were 8,1600x102, 1,7535x103 and 4,0154x102, where α < 104 include to direct transition. Band gap energy 400oC, 600oC, 800oC were 3,79 eV, 3,59 eV, and 3,35 eV, respectively. Based on this result, exhibition that band gap energy of TiO2 semiconductor film decreased with increasing annealing temperature. Spirulina platensis was cultivated in technical modification (Hastuti) with aeration under light intensity about 3000 lux. The cell density (stationer phase) for eighth day which OD value was more than 0,5. It means, the culture can be harvested. In 80 liters Spirulina platensis culture have been produced biomass dry about 10,46 gram and extracted phycocyanin in dry powders was 5,50 gram. The phycocyanin absorption spectrum at the wavelength of 619,36 nm (visible region) which had relaxation energy was 2,945 eV. The emission peak at the wavelength of 708,55 nm with relaxation energy about 2,793 eV. The Stokes shift based on difference energy absorption and emission calculated about 0,152 eV. Both of this showed phycocyanin can absorbed and radiated the sun light which received. This choice characteristic pigment was a good one related to sensitizer in solar cell application. Integration between light harvesting protein and TiO2 semiconductor surface had important role in improving of output as solar cell materials. The presence of carboxylate group (-COOH) made pigment be more efficient was due to anchored to the surface of TiO2 ampoter. The phycocyanin pigment had carboxylate group which reacted with TiO2 surface formed ester. The carboxylate group increased of dye electronics couple from excited state (p anti bonding orbital) to semiconductor acceptor state (TiO2 conduction band). The samples which made based on annealing temperature variation formed be solar cell respectively. Furthermore, cells be assembled for
Keyword: anatase, dye sensitized solar cell, efficiency, gap energy, phycocyanin