Judul: Performance Test of Soil Volume Measurement Instrument with Air Pressure Principle
Abstrak: Perbandingan volume fase padat, cair, dan gas pada tanah merupakan hal yang penting karena mempengaruhi sifat fisik tanah dan pertumbuhan tanaman. Total volume fase padat dan cair tanah disebut sebagai volume aktual. Bila volume aktual diketahui, sifat-sifat fisik dasar tanah dapat diperoleh dengan sangat sederhana dan sistematis. Salah satu sifat fisik yang dapat ditentukan adalah kadar air. Alat ukur volume tanah yang sudah sering digunakan adalah Three Phase Meter OSK 10014R Serial No.1855 Ogawa seiki. Namun, alat tersebut memiliki harga yang cukup mahal. Oleh karena itu, dibuat alternatif alat lain dengan prinsip yang sama dan harga yang lebih terjangkau, yang disebut Three Phase Meter sederhana. Penelitian ini bertujuan menguji ketelitian serta ketepatan alat Three Phase Meter sederhana untuk pengukuran volume aktual pada tanah gambut dengan menerapkan prinsip hukum Boyle. Alat diuji menggunakan sampel benda padat volume 0 ml, 30 ml, 50 ml, dan 80 ml sebagai standar. Sampel dimasukkan ke dalam tabung alat, lalu ditambahkan udara melalui syringe sehingga tekanan udara di dalam tabung mencapai 8 kPa. Setelah berhasil diuji menggunakan standar, alat diuji dengan contoh tanah gambut utuh dalam ring sampler berukuran 100 cm3. Pengujian ketelitian dilakukan dengan cara pengukuran 5 kali ulangan, sedangkan ketepatan diketahui dengan membandingkan hasil pengukuran dengan hasil teoritis. Volume aktual tanah gambut yang didapatkan dari pengukuran menunjukkan hasil yang tidak jauh berbeda pada antar ulangan. Hasil pengujian ketelitian alat menunjukkan rata-rata nilai sebesar 99.5%. Hasil pengukuran alat dan teoritis menunjukkan nilai rata-rata ketepatan sebesar 97.9% dengan nilai kesalahan relatif kecil, yaitu sebesar 2.1%. Nilai tersebut menunjukkan bahwa pengukuran menggunakan Three Phase Meter sederhana memiliki ketepatan yang tinggi karena nilai pengukuran dengan alat mendekati nilai teoritis. Dengan demikian, alat Three Phase Meter sederhana layak digunakan untuk mengukur volume aktual pada tanah., The volume ratio of the solid, liquid, and gas phases of soil is important because it shows the physical properties of soil and affects plant growth. The total volume of solid and liquid phases of soil is referred to the actual volume. When the actual volume is known, the basic physical properties of soil can be obtained simply and systematically, such as water content. The common instrument which is used for measuring soil volume is Three Phase Meter OSK 10014R Serial No.1855 Ogawa Seiki. However, the instrument is quite expensive, therefore, an alternative instrument with same principle and more affordable price was created, called a simple Three Phase Meter. This study aimed to test the performance, such as the accuracy and the precision of the simple Three Phase Meter with the application of Boyle's law principle, to measure the actual volume of peat soil. The instrument was tested using solid samples with volumes of 0 ml, 30 ml, 50 ml, and 80 ml as standards. The sample was inserted into the instrument tube and then air was added through syringe so that the air pressure in the tube reached 8 kPa. After successfully testing the solid samples, the instrument was tested with samples of peat soil in a ring sampler measuring 100 cm3. The instrument precision was known by repeating the measurement five times, while the
Keyword: gambut, kadar air, tekanan udara, Three Phase Meter, volume aktual

Judul: Pengukuran Retensi Air Tanah Gambut Menggunakan Kombinasi Three Phase Meter dan Ceramic Plate
Abstrak: Characterization of physical properties of tropical peat soil were mostly done based on the characterization of subtropical peat, without considering the differences between them. Among the physical properties of tropical peat, water retention and particle density (PD) are rarely measured. Appropriate measurement method for both are obviously required because these values are very important in peatlands management. This study was aimed to measure water retention of peat soil, to understand the water retention, to draw the pF curves and also to study the effect of changes in soil moisture content on peat volume. Peat soil samples were taken from three locations with different reclamation age. Peat water retention were measured using Ceramic Plate, peat volume were measured using Three Phase Meter, and pF curve equation was made using Genucthen (1980) model. The results showed that the pattern of soil water retention in peat at three locations with different land uses were similar. Water in peat soil was easily lost at low pressure ( pF 0-2 ) and strongly bound by peat soil material at a higher pressure ( pF 2-4.2 ). Peat pore was dominated by fine pore ( ± 40 % v/v ) and very fast drainage pore ( ± 30 % v/v ). Interval of available water was very small ( < 10 % v/v ). The changes of water content would affect the volume of peat. Peat soils swell and shrink significantly. The intensity of the swell and sringkage are estimated to depend on the origin and degree of decomposition of peat materials. PD of peats were found to vary, so direct measurement must be performed.
Keyword: water retention, pF curves, peat, Genucthen

Judul: Penyusunan Overlap Graph menggunakan Suffix Tree pada DNA Sequence
Abstrak: The DNA sequence assembly is very important in genome analysis. This step aims to reconstruct contigous DNA fragment (contigs) from short fragment by concatenating fragments based on the overlap region among them. This method employs overlap graph for solving the problems. In this graph, nodes represent fragments and edges represent overlap. This research developed a software for constructing overlap graph using suffix tree. The evaluation was conducted by measuring the number of nodes, number of edges, and the execution time in many values of minimum overlap. The minimum overlap is defined as the minimum length of substring which is considered as the overlap region between two fragments. The evaluation results showed that the number of nodes, the number of edges, and the execution time were increased with the decreasing of the minimum overlap value.
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