Judul: Kegunaan data anomali suhu muka laut Pasifik (NINO 3.4) untuk prediksi produksi padi di Indonesia
Abstrak: Indonesia as the third largest producer of rice still frequently experience the crop failure due to extreme climate events. The decline of rice production will lead to instability of food security since the rice price will rising and harm poor people who spend a larger portion of their income on rice than do wealthier member of society. This study aims to know the relationship between the rice production at each province in Indonesia with the sea surface temperature anomalies (SSTA) of Nino 3.4, which is one index of ENSO. The correlation between SSTA Nino 3.4 with paddy production ranged between 0.40 to 0.70, which means that the SSTA of Nino 3.4 data has a strong correlation with paddy production data so it can be used as a predictor. The correlation shows that if SSTA Nino 3.4 increasing (El-Nino event), the rice production on January-April declining, while the production on Mei-August and on September-December rising, it is due to the advancing of planting date. But the increase of rice production on Mei-August and on September-December are not as big as the decline on January-April. The provinces that their rice production are influenced by ENSO are the provinces which the rainfall type are monsoon. The best predictor for paddy production is SSTA September one year before. R2 of the prediction model for January-April production >40% which means that the model is good to explain the diversity of production data. While the model for Mei-August and on September-December production are not considered good to explain the diversity of the production data. It is expected that these forecast can be used by the governments and other parties who have interest in establishing a strategy in order to maintain the stability of food security in Indonesia.
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Judul: The Analyse of Oil Palm Productivity Prediction Using Anomaly of Sea Surface Temperature at Nino-3,4
Abstrak: Yield variability of oil palm (fresh fruit bunch, FFB) is determined by interaction between genetics, ages, environmental (soil and climate), and technical culture factors. Climate factor may explain most of the yield variability if other factors are not very variable. One of the main climate factors affecting the yield of palm oil in Indonesia is rainfall. This study was conducted to evaluate impact of rainfall variability on production of palm oil in 26 big plantations in Sumatra Island with assumption that conditions of non-climatic factors such as varieties (genetic), technical culture is relatively homogenous. As many studies suggest that rainfall variability in Indonesia is strongly influenced by ENSO phenomenon, we analyse the potential use of ENSO index (based on anomaly of sea surface temperature/ASST at Nino-3,4) to predict palm oil yield in the plantations. The prediction models was developed using a number of steps. First is to remove the effect of age and seasonality of palm oil yield from the data series using non linear equation and Fourier regression (called as detrended yield). Second is to develop relationship between the anomaly of the detrended yield and anomaly of ASST in region 3,4. Third is to construct model to predict palm oil production in the plantation using stochastic spreadsheet based on equations developed in the previous steps. The result of analysis showed that the non-linear function can explain well the relationship between yield and age. The model could explain between 60% and 90% of the variability of palm oil production across the 26 plantations. Furthermore, the study suggests that the ENSO impact on yield variability was only significant in seven plantations located in areas that have south moonsonal rainfall type (South part of Sumatra such as part of Jambi, Lampung and South Sumatra). It was found that the ASST in region 3,4 is potential to be used for predicting production of palm oil in the seven plantations. The result of validation showed that there is no significant different between observed and predicted data (tvalue < ttable; α=1%).
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular