Judul: Effect of Vegetation Density and Soil Physical Characteristics on Infiltration Rate in the Jasinga Silviculture Teaching Industry (JSTI) Area
Abstrak: Hutan Jasinga Silviculture Teaching Industry (JSTI) termasuk hutan penelitian dengan kondisi ekosistem yang belum banyak diketahui. Dibutuhkan penelitian pada ekosistem setempat terutama terkait vegetasi, tanah, dan siklus hidrologi. Tutupan lahan vegetasi di Hutan JSTI belum merata yang memengaruhi resapan air tanah (laju infiltrasi). Penelitian ini bertujuan mengidentifikasi komposisi vegetasi dan sifat fisik tanah yang memengaruhi laju infiltrasi. Plot ditentukan melalui teknik purposive sampling berdasarkan kerapatan vegetasi. Komposisi vegetasi diketahui berdasarkan indeks nilai penting (INP). Laju infiltrasi diukur menggunakan double-ring infiltrometer. Hasil penelitian menunjukkan bahwa komposisi vegetasi bervariasi sesuai dengan tingkat kerapatan tajuk. Struktur tanah berupa subangular blocky dengan tekstur liat, kadar bahan organik tergolong tinggi (>4%), bulk density tergolong sedang, porositas yang didominasi kategori porous, serta kadar air dan laju infiltrasi plot vegetasi rapat cenderung lebih besar dibandingkan plot vegetasi jarang. Parameter kerapatan vegetasi dan sifat fisik tanah yang dianalisis memiliki pengaruh yang kuat hingga sangat kuat dengan laju infiltrasi tanah., The Jasinga Silviculture Teaching Industry (JSTI) forest is a research forest with ecosystem conditions that have yet to be widely known. Research on the local ecosystem is needed, especially regarding vegetation, soil, and the hydrological cycle. Vegetation land cover in the JSTI Forest is uneven, which affects groundwater absorption (infiltration rate). This study aims to identify the vegetation composition and soil physical properties that affect the infiltration rate. Plots were determined through a purposive sampling technique based on stand density. Vegetation composition is known based on the important value index (IVI). The infiltration rate was measured using a double-ring infiltrometer. The results showed that the composition of the vegetation varies according to the level of crown density. The soil structure is subangular blocky with a clay texture, the organic matter content is high (> 4%), the bulk density is moderate, the porous category dominates the porosity, the water content and infiltration rate of dense vegetation plots was more excellent than sparse vegetation plots. Vegetation density parameters and soil physical properties analyzed have a strong to very strong relations with soil infiltration rate.
Keyword: erosion, vegetation density, groundwater infiltration

Judul: Keragaan Infiltrasi Tanah Latosol pada Beberapa Penggunaan Lahan di DAS Ciujung
Abstrak: Land use is an important aspect in maintaining ecosystem sustainability, particularly in the watershed ecosystem. Land use determines to physical, chemical, and biological characteristics of soil. These soil characteristics influence to the growth of plants and the performances of water infiltration into soil. Infiltration is an essential part of the hydrological cycle that has an important role water availability in the soil. Infiltration process have an important role to the distribution of rainfall and control to runoff, flood, erosion and ground water storage and finally will determines the availability of river discharge in dry season. The aims of this research is to assess the performance of soil infiltration in various land use in Ciujung watershed. The study was conducted on three land use types that included plantative forest (HT), dense mixed garden (KCR), and less-dense mixed garden (KCTR). The field observation was done by using the Double Ring infiltrometer method, while the the analysis of the physical and chemical and other soil characteristics were done in the Laboratory of Soil and Water Conservation, Department of Soil Science and Land Resources, Faculty of Agriculture. The results of this research showed that the infiltration rate is strongly influenced by land use. Infiltration rate is the highest and most stable on HT land use, followed by KCR and KCTR. Constant infiltration rate at HT and KCR is belonging to quickly class, while at KCTR is relatively moderate to fast. The magnitude of the rate constant infiltration in HT (23.4 cm h-1) is higher than KCR (13.2 cm h-1) and KCTR (6.0 cm h-1). The high rate infiltration of the soil on the land use of HT support it able to accommodate as much water (6.45 dm3) that higher than at KCR (3,66 dm3) and at KCTR (1.52 dm3). Infiltration rate is influenced by pores with large size (PDSC), while the volume of water infiltration is more influenced by the total porosity of the soil. Besides it is influenced by land use, soil infiltration in the study area is also determined by the physical and chemical characteristic of the soil organic matter, bulk density, total porosity, aggregate stability, macro pores, very fast drainage pore (PDSC), and soil texture.
Keyword: Bogor Agricultural University (IPB), infiltration volume., physical and chemical characterstics of soil, land use, Infiltration rate

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: