Judul: Rainfall Prediction with Ridge Regression and LASSO Regression Based on TRMM (Case Study: Rainfall in Indramayu)
Abstrak: Curah hujan tidak mudah untuk diprediksi. Salah satu tujuan prediksi ini adalah melengkapi data hilang yang terjadi saat pengamatan. Data presipitasi dari satelit, Tropical Rainfall Measuring Mission (TRMM), digunakan untuk tujuan tersebut. Seringkali data dari titik koordinat TRMM terdekat ataupun rataan dari beberapa titik koordinat TRMM sekitarnya digunakan untuk mengisi data pengamatan yang hilang. Metode regresi LASSO dan regresi gulud digunakan untuk pendugaan data amatan curah hujan yang hilang dan bebas dari multikolinearitas. hasilnya menunjukkan bahwa nilai RMSEP pemodelan sebesar 63.110 untuk regresi gulud dan 64.307 untuk regresi LASSO. Hasil tersebut masih lebih besar daripada hasil metode regresi linier berganda dengan RMSEP pemodelan sebesar 60.511. Namun setelah menambahkan peubah boneka bulan pada metode regresi gulud dan regresi LASSO nilai RMSEP pemodelan adalah berturut-turut sebesar 57.216 dan 56.044.
Keyword: Bogor Agricultural University, Institut Pertanian Bogor, IPB, LASSO, Rainfall, Ridge regression, TRMM, Pendugaan data amatan, Data yang hilang, Data satelit

Judul: Pengembangan Model Penduga Hujan Bulanan Menggunakan Data Satelit TRMM pada Tiga Pola Hujan di Indonesia
Abstrak: Rainfall is one of the atmosphere parameters which is quite difficult to predict because of its very high variability on space and time. The recent development of rainfall observation technology nowadays is using rainfall satellite. This satellite has near real time rainfall monitoring, wide coverage and fast access. In this study, climatological analysis of rainfall pattern, statistical analysis to evaluate and validate TRMM data using selected ground stations and TRMM data, development of correction factor for TRMM data and monthly rainfall prediction using ARIMA model, have been done in three regions with different rainfall pattern. Those areas are monsoonal pattern in Lampung, East Java and Kalimantan Selatan; equatorial pattern in North Sumatera and West Kalimantan; and local pattern in Maluku. The validation analysis showed very high correlation with the gauge data for monsoonal pattern area (>0.80), high correlation for equatorial (>0.60) and local pattern area (>0.75). Each pattern area has a correction equation. In general, the error of corrected TRMM data decreased for monsoonal, equatorial and local pattern. The model of monthly rainfall prediction has been developed for corrected TRMM data with 95% level significance. The verification of model showed high coefficient correlation (r) in local pattern and monsoonal pattern, but lower on equatorial pattern.
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Judul: Bioelectricity Production from Citrobacter freundii GBH253 and Chlorella pyrenoidosa on Microbial Fuel Cell Anode with Different Carbon Sources
Abstrak: Microbial Fuel Cell (MFC) development has significantly increased from various aspects to get higher and more stable electricity. Developing MFC on microorganism aspect is very important because it plays a crucial role in the MFC system. C. freundii GBH253 is one of the potential exoelectrogen bacterium that could be developed for the MFC system. Integrating C. freundii GBH253 and electricity-producing microalgae, such as C. pyrenoidosa, in the anode of MFC could get more stable and higher electricity. In this study, C. freundii GBH253 and C. pyrenoidosa were coupled to produce electricity from different substrates. C. freundii GBH253 and C. pyrenoidosa were tested on three different media types before being tested on MFC. They were also examined for the co-cultivation test to determine the symbiotic relationship between the two microorganisms. The MFC test was conducted using the Randomized Block Design Factorial and the Tukey test to see significant differences from each treatment. The parameters observed in this study were voltage, power density, Chemical Oxygen Demand (COD), Coulombic Efficiency (CE), pH, and volatile fatty acid (VFA). C. freundii GBH253 cannot grow on microalgae medium, while C. pyrenoidosa could grow on bacterial medium and a mixture of bacterium and microalgae media. The bacterium gained benefit from co-culture with microalgae. In the MFC test, electricity was generated in all treatments, which bacterium + microalgae with acetate treatment could generate power density up to 211,97 mW/m2 and the most stable compared to others. Production of electricity in bacterium-microalgae combination dominated by the bacterium; hence, microalgae still help bacterium by producing electricity and raised the COD value. The pH value of all treatments was higher than the initial pH. Acetate and phenol were VFA produced in all treatments, whereas butyric acid and propionic acid were found in some treatments. Pearson correlation showed that some VFA highly correlated with power density.
Keyword: Chlorella pyrenoidosa, Substrate, Microbial Fuel Cell, Electricity Producing Microalgae, Volatile Fatty Acid, Citrobacter freundii