Judul: Deteksi Nilai Hambur Balik Berbagai Objek (Bola sphere, Keramba dan Dasar watertank) Menggunakan Instrumen Single Beam Transducer
Abstrak: Nilai hambur balik dari setiap target memiliki nilai hambur balik yang berbeda-beda hal tersebut di karenakan setiap target memiliki karakteristik yang berbeda-beda. Alat hidroakustik akan mengirimkan sinyal suara berupa echo ketika mengenai obyek, kemudian sinyal tersebut di tampilkan dalam bentuk echogram. Tujuan penelitian ini yaitu menganalisis nilai hambur balik dari objek bola sphere, karamba dan dasar watertank. Hasil yang di peroleh yaitu nilai Target Strength dari bola Sphere sebesar -40.56 ± 5.5dB untuk nilai Volume backscattering Strenght keramba sebesar -40.76 ± 3.42 dB sedangkan untuk nilai Surface Scattering Strenght dari dasar watertank adalah -1.23 ± 2.56 dB. Penelitian ini membuktikan adanya perbedaan nilai hambur balik dari setiap objek yang berbeda-beda.
Keyword: hidroakustik, hambur balik, bola sphere, karamba, watertank

Judul: Deteksi Objek Dasar di Perairan Punggur Batam berdasarkan Nilai Hamburbalik Akustik
Abstrak: Deteksi objek dasar perairan merupakan proses analisa objek yang menggunakan kemampuan teknologi sonar. Side scan sonar (SSS) adalah alat yang menggunakan komponen satu beam (Single beam) yang dapat menampilkan citra dalam bentuk dua dimensi (2D). Tujuan dari penelitian ini adalah menganalisa dan mendeteksi objek dasar perairan. Data side scan sonar dengan format Xtf diproses dengan menggunakan koreksi radiometrik dan geometrik melalui perangkat lunak SonarWiz 7 untuk mendapatkan klasifikasi citra. Proses ekstraksi data menggunakan perangkat lunak SeiSee 2.2 untuk menampilkan nilai amplitudo dan waktu. Trace diambil sesuai nomor ping target. Trace data dikonversi ke dalam format txt atau xls kemudian data trace diinput ke dalam perangkat lunak Matlab r2017a untuk menampilkan grafik amplitudo (mV). Analisis hamburbalik menggunakan perhitungan logaritma yaitu 20Log10 (Vt/V0) dengan Vt merupakan dominan dan V0 amplitudo maksimum. Berdasarkan hamburbalik SSS di perairan Punggur Batam diperoleh 6 target yang memiliki nilai hamburbalik -3,32 dB, -5,71 dB, -1,13 dB, -6,81 dB, -4,86 dB, dan -3,74 dB. Besar kecilnya nilai hamburbalik yang didapatkan dipengaruhi oleh amplitudo target., Detection of underwater objects is an object analysis process that uses the capabilities of sonar technology. Side scan sonar is a tool that uses Single beam which can display images in two dimensions (2D). The purpose of this study is to analyze and detect objects on the bottom of the waters. Side scan sonar (SSS) data in Xtf format was processed using radiometric and geometric corrections with SonarWiz 7 software to obtain image classifications. The data extraction process used SeiSee 2.2 software to show the amplitude and time values. Traces were taken based on the target ping number. The trace data were converted into txt or xls format then the trace data was inputted into the Matlab r2017a software to show an amplitude (mV) graph. The backscatter analysis used a logarithmic calculation, 20Log10 (Vt/V0) with Vt being the dominant and V0 being the maximum amplitude. Based on the SSS backscattering in the waters of Punggur Batam we got 6 targets which had backscatter values about -3.32 dB, -5.71 dB, -1.13 dB, -6.81 dB, -4.86 dB, and -3.74 dB. The size of the backscatter value was influenced by the target amplitude.
Keyword: Backscatter, Punggur Waters, Side Scan Sonar

Judul: Lejeuneaceae Subfamily Ptychanthoideae (Hepaticae) in  West Java
Abstrak: Subfamily Ptychanthoideae of the family Lejeuneaceae (Hepaticae) in West Java is still poorly known. Publications on this subfamily are out of dated and written in the 19th or early of 20th century. The last taxonomic treatment of Ptychanthoideae of West Java was in 1933, many species names have changed since then. Studies on Ptychanthoideae of West Java are urgently needed. Studies on the Ptychanthoideae were based on the specimens collected from West Java. A total number of 361 of specimens deposited in the Herbarium Bogoriense (BO), Herbarium Biotrop (BIOT), Gottingen Herbarium (GOET) and Bangi Herbarium (UKMB) were examined, those are old and several recent specimens collected in West Java. Recent collections were made from Telaga Warna, Ciater, Gunung Halimun Salak National Park, Cibodas Botanical Garden, Bodogol Education Center and Conservation (Gunung Gede Pangrango National Park), University of Indonesia Campus Depok, including several collections from Banten Province. Twenty four species of Lejeuneaceae subfamily Ptychanthoideae are known from West Java, belonging to 8 genera namely Acrolejeunea (Spruce) Schiffn. (2 species), Archilejeunea (Spruce) Schiffn. (1 species), Lopholejeunea (Spruce) Schiffn. (10 species), Mastigolejeunea (Spruce) Schiffn. (3 species), Ptychanthus Nees (1 species), Schiffneriolejeunea Verd. (1 species), Spruceanthus Verd. (2 species) and Thysananthus Lindenb. (4 species). Two new records of Ptychanthoideae: Mastigolejeunea indica Steph. and Thysananthus minor Verdoorn are reported for Java. A determination key to the species is presented including their descriptions and illustrations.
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