Judul: Karakteristik Kekeringan Hidrologi di Wilayah Kalimantan Bagian Timur
Abstrak: This study aimed to identify the hydrological drought using groundwater recharge component and analyze the relation between hydrological drought and ENSO phenomena. Water balance model with monthly rainfall and ETp input was used to assess the monthly recharge value from 1901 to 2009. In this study we used a monthly varying threshold method. The threshold varied depending on the climate regime and soil condition. Drought in groundwater was considered when the monthly recharge is below the drought threshold. We found that the longer drought duration, the volume deficit would significantly increase. Additionally, the longer drought duration, the number of drought events would significantly reduce. This study indicates that Samarinda region under peat soil and forest cover is more prone to drought as indicated by the highest drought frequency (56). In other hand, Banjarmasin region under mineral and forest cover is less vulnerable to drought. Furthermore, this study shows that peat soils are more pronounced to severe drought than mineral soils. Our findings also confirmed that strong El-Niňo would trigger severe hydrological droughts.
Keyword: Bogor Agricultural University (IPB), ENSO, duration, threshold, volume deficit, recharge

Judul: Karakteristik Kekeringan Hidrologi pada Wilayah Kalimantan Bagian Barat
Abstrak: Hydrological drought is a drought type, which influences the availability of water bodies including groundwater. This study aimed to analyze the characteristics of hydrological drought and their relationship with El Niño (ENSO) in the western part of Kalimantan. This study used a soil water balance model to estimate monthly groundwater recharge with an input of monthly air temperature and rainfall for 1901-2009. The model was run for two different two soil types (mineral and peat) under natural forest. Hydrological drought on groundwater recharge was identified using monthly varying threshold method. We found that drought duration was about two to five consecutive months either in peat or mineral soil. The southern part of the region was more prone to drought particularly for peat soil. Furthermore, our study confirmed that hydrological drought are more severe than meteorological drought as indicated by the largest duration of drought in recharge until eleven months, whereas meteorological drought only nine months. In strong El Niño years, drought occurences are more severe as indicated by high deficit volume
Keyword: Bogor Agricultural University (IPB), deficit volume., recharge, ENSO, duration, threshold

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
Keyword: