Judul: Analisis Nilai Intensitas Hamburbalik Multibeam Echosounder untuk Klasifikasi Sedimen di Pulau Damar Besar, Kepulauan Seribu
Abstrak: Salah satu teknologi hidroakustik yang dapat digunakan untuk klasifikasi dan memetakan jenis sedimen dasar perairan adalah multibeam echosounder (MBES). MBES memancarkan lebih dari satu beam dengan pola pancaran melebar dan memanjang dari badan kapal. Penggunaan MBES dapat menghasilkan data hamburbalik yang mampu menentukan jenis dasar perairan. Tujuan penelitian ini untuk mengklasifikasi sedimen dasar perairan Pulau Damar Besar. Klasifikasi sedimen dilakukan dengan melihat nilai intensitas hamburbalik dan ditentukan jenis sedimen berdasarkan nilai rentang hamburbalik dalam pembagian kelas yang sudah ada pada data penelitian terdahulu. Selain itu klasifikasi sedimen ditentukan berdasarkan visual dan tesktur dari pengambilan sedimen di lapang. Sedimen dasar perairan Pulau Damar Besar dapat diklasifikasikan menjadi 8 kelas dengan rentang nilai hamburbalik yaitu lumpur halus -34.92 dB s/d -33.01 dB, lumpur sedang -32.99 dB s/d -31.01 dB, lumpur kasar -30.99 dB s/d -30.55 dB, pasir lanauan -28.99 dB s/d -27 dB, pasir berlumpur -26.99 dB s/d -25 dB, pasir liat -24.99 dB s/d -23 dB, pasir sangat halus -22.99 dB s/d -21.01 dB, dan pasir halus -20.99 dB s/d -19.04 dB., One of hydroacoustic technology that can be used to classify and map the type of bottom water sediment is multibeam echosounder (MBES). MBES emits more than one beam with a scatter pattern widening and extending from the ship's body. The use of MBES can produce backscatter data that is able to determine the type of bottom water. The purpose of this study was to classify the sediments of Damar Besar Island bottom water. Sediment classification was carried out by looking at the value of backscatter intensity and determining the type of sediment based on the value of the scattering range in the class division that already exists in the previous research data. In addition, the classification of sediments was determined on the basis of visuals and texture from taking sediments in the research location. The sediment of the bottom water of Damar Besar Island can be classified into 8 classes with a backscatter intensity value range, namely fine silt -34.92 dB to -33.01 dB, medium silt -32.99 dB to -31.01 dB, coarsed silt -30.99 dB to -30.55 dB, silty sand -28.99 dB to -27 dB, muddy sand -26.99 dB to -25 dB, clayed sand -24.99 dB to -23 dB, very fine sand -22.99 dB to -21.01 dB, and fine sand -20.99 dB to -19.04 dB.
Keyword: backscatter intensity, sediment classification, multibeam echosounder, Damar Besar Island, bottom water sediment

Judul: Pengukuran dan analisis nilai hambur balik akustik untuk klasifikasi dasar perairan dan hubungannya dengan makrozoobentos di Delta Mahakam
Abstrak: Riverbed substrate is a one of potential abiotic resources. It is useful as habitat, foraging area, and spawning area for most aquatic organisms (Susanto 2000). Riverbed has a very complex substrate composition from small sized substrate into rocky substrate. Over exploitation makes the quality and composition of bottom waters changed. Research on aquatic habitats are usually based on a sampling basis using a corer or a van veen grabber (Romimohtarto and Juwana 2009). But it is not time efficient, covering only narrow area and can be applied only in limited location. One of method that can help to overcome this deficiency is using hydroacoustic technology. Hydroacoustic technology is a technology which used to detect underwater objects by using sound propagation. Acoustic classification system of bottom substrate can predict the substrate type and its geotechnical properties. Hydroacoustic also has been widely used in various applications including marine geology, civil engineering, military science, and fisheries (Lambert et al. 2002; Richardson et al. 2002). This technology is able to provide information regarding the relief of the bottom, fish density, direction and movement of fish, as well as the type of bottom substrate in a relatively rapid and extensive reach. Sea bottom has characteristic in reflecting and scattering sound waves as well as the waters of the sea surface. The resulting effect is more complex due to the nature of the sea floor that is composed of diverse elements ranging from hard rock to soft clay and layers that have different compositions (Urick 1983). Some initial researches on aquatic habitats in Indonesia have been conducted by Manik et al. (2006) using the measurement of surface backscattering strength (SS) of Quantitative Echo Sounder (QES) and the SS value for identification of fish habitat, Pujiyati (2008) which using hydroacoustic method for relationship analysis between bottom substrate types with fish demersal community, Harahap (2010) in quantification of the value of bottom acoustic backscatter using multibeam echosounder, and Allo (2011) which applying the method of Manik et al. (2006) for the quantification and characterization of acoustic backscattering of bottom habitat in the Seribu island. This study was conducted in two phases. The first phase is collection of field data and the second is data processing and analyzing phase. Acoustic data collected were using hydroacoustics instrument SIMRAD EY60 120 kHz frequency and recorded by ER60 software. Sampling substrate was conducted at 9 stations acoustic data recording. Analysis of acoustic data include the value of SV E1, SV E2, and SS. Analysis of the substrate data include the percentage of the fraction (sand, silt, clay), and macrozoobenthos (density, diversity, dominance). Analysis of the relationship between acoustic values, the fraction of the substrate, and macrozoobenthos are using Principal Component Analysis (PCA). The results showed that the type of substrates that are found on sites are sand, muddy sand, sandy mud, and mud. Based on the value of SS for sand (- 12.97 dB), muddy sand (-13.96 dB), sandy mud (-17.14 dB and -15.64 dB), and mud (-30.87 dB to -19.25 dB). It shows also that sand has a high substrate roughness, hardness, and
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf