Judul: Studi Metode Infiltrasi Falling Head dan Constant Head pada Beberapa Variasi Ketinggian Genangan Air
Abstrak: Field measurement of infiltration rate using both of falling head and constant head method has an opportunity to generate different infiltration capacity values due to the different of hydraulic head and the way of water being added to infiltrometer. The purpose of this study was to compare the infiltration capacity based on falling head and constant head method and to see the effect of various hydraulic head in the infiltrometer on the infiltration capacity. Infiltration field measurement was done in Latosol Darmaga, Bogor. Falling head method was done in two different ways, namely within a certain time interval and within a certain water drop interval. Hydraulic head used during measurement were 10 cm, 15 cm, and 20 cm. The falling head and constant head method generated different infiltration capacity values. The falling head method based on time interval generated different values of infiltration capacity at 10 cm, 15 cm, and 20 cm hydraulic head of respectively 5.07 cm/hour, 6.13 cm/hour, and 4.67 cm/hour. The falling head method based on water drop interval at 10 cm, 15 cm, and 20 cm hydraulic head generated infiltration capacity values of respectively 17.47 cm/hour, 17.18 cm/hour, and 20.60 cm/hour. The constant head method at 10 cm, 15 cm, and 20 cm hydraulic head generated infiltration capacity values of respectively 15.77 cm/hour, 24.17 cm/hour, and 25.90 cm/hour. Infiltration field measurement using the falling head method either based on time interval or water drop interval did not show an increasing trend of infiltration capacity values due to the increase of hydraulic head. However, the infiltration field measurement using constant head showed an increasing trend of the infiltration capacity values due to the increase of hydraulic head.
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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: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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