Judul: Penurunan Habitat Mangrove dengan Pendekatan Spasial sebagai Dasar Pengelolaan Ekosistem di Muara Sungai Sesayap, Tana Tidung, Kalimantan Utara.
Abstrak: Ekosistem mangrove di muara Sungai Sesayap mengalami penurunan luasan akibat konversi lahan. Penelitian ini bertujuan untuk menentukan kondisi mangrove berdasarkan luas habitat dan kualitas lingkungan. Penelitian dilakukan di muara Sungai Sesayap. Pengambilan sampel tanah dan air menggunakan metode purposive sampling. Sampel sediman diambil pada tanggal 22 Juli 2017 dan pengambilan sampel air pada tanggal 24 September 2017. Kualitas perairan yang digambarkan oleh suhu, salinitas, TDS, TSS, COD dan BOD masih mendukung terhadap pertumbuhan mangrove. Namun tingkat kekeruhan perairan tersebut tinggi. Jenis tekstur sedimen pada lokasi penelitian didominasi oleh fraksi lumpur. Sedimen di lokasi ini masih mendukung terhadap pertumbuhan mangrove meskipun kandungan Mg pada tanah rendah. Luas tutupan lahan mangrove pada tahun 2005 seluas 6350 hektar dan pada tahun 2017 seluas 4225 hektar. Luasan Mangrove di muara Sungai Sesayap mengalami degradasi karena adanya konversi lahan menjadi tambak. Luas tutupan mangrove yang berkurang perlu di lakukan pengelolaan untuk memulihkan fungsi serta manfaatnya.
Keyword: koversi lahan, mangrove, sedimen, tambak

Judul: Kajian Pengelolaan Ekosistem Mangrove Secara Berkelanjutan Kota Tarakan Kalimantan Timur (Studi Kasus Desa Binalatung Kecamatan Tarakan Timur)
Abstrak: Potensi sumberdaya pesisir Kota Tarakan, hingga saat ini belum mengalami pengelolaan yang optimal. Ekosistem hutan mangrove merupakan salah satu potensi yang dimiliki, dan saat ini mengalami degradasi yang sangat tinggi. Kondisi tersebut akan berdampak terhadap keberlanjutan pembangunan di masa yang akan datang. Pengelolaan sumberdaya secara optimal dan berkelanjutan akan memberikan manfaat terhadap masyarakat (welfare society) dan manfaat terhadap negara (welfare state). Tujuan penelitian yaitu 1) Mengetahui potensi dan permasalahan pemanfaatan ekosistem hutan mangrove, 2) Merumuskan alternatif pengelolaan ekosistem hutan mangrove. Penelitian ini bersifat studi kasus (case study) dengan mengambil data primer dan data sekunder. Analisis yang dilakukan adalah analisis potensi biofisik, analisis NET (nilai ekonomi total) dan analisis MCDM (multy criteria decision making). Hasil penelitian diperoleh bahwa nilai kerapatan relatif jenis (RDi) api-api (Avicennia sp) sebesar 51,37% dan prepat (Sonneratia sp) sebesar 48,63%, nilai frekuensi relatif jenis (RFi) api-api (Avicennia sp) sebesar 50% dan prepat (Sonneratia sp) sebesar 50%, nilai penutupan relatif jenis (RCi) api-api (Avicennia sp) sebesar 49,86% dan prepat (Sonneratia sp) sebesar 50,14%, berdasarkan hasil tersebut diperoleh bahwa peranan api-api (Avicennia sp) lebih dominan dalam ekosistem dibanding dengan jenis prepat (Sonneratia sp) dengan indeks nilai penting (INP) untuk api-api (Avicennia sp) sebesar 151,23 dan prepat (Sonneratia sp) sebesar 148,77. Nilai ekonomi total (NET) diperoleh Rp.1.112.305.240. Hasil pengamatan dan pengukuran diperoleh bahwa penyebab utama terjadinya degradasi hutan mangrove yakni sedimentasi di muara sungai dan genangan air tawar yang tinggi. Untuk itu diperlukan alternatif pengelolaan ekosistem hutan mangrove kedepan. Berdasarkan hasil analisis MCDM diperoleh bahwa program rehabilitasi kawasan hutan mangrove merupakan alternatif utama dengan nilai keputusan 0,525, dan alternatif kedua yakni program pengelolaan DAS dengan nilai keputusan 0,418.
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Judul: Algorithm Construction of HLI Hash Function
Abstrak: Cryptography is a study of mathematical techniques related to aspects of information security regarding on confidentiality, data integrity, entity authentication, and data origin authentication. Data integrity is a service, which is associated with the conversion of data carried out by unauthorized parties. To maintain data integrity, one can use hash functions. An hash function is a computationally efficient function to map an arbitrary length bitstring to a fixed length bitstring called as hash value. The use of hash function in maintaining the information integrity and authentication is in digital signatures, virus protection, and software distribution. Illustration of the hash function in the integrity and authentication of information that is emailed as follow. The sender sends the information and hash value to the recipient. If the hash value of the information is equal to the hash value that is sent by the sender, then information has not been changed. Otherwise the information has been changed. An hash function has two properties, one way and collision resistance. An hash function is called one way if it is computationally infeasible to find any input such that when given any hash value . Meanwhile an hash function is called collision resistant if it is computationally infeasible to find any two inputs where such that . The purpose of this study is to construct a HLI hash function algorithm, to analyze the speed and security of the hash functions as a results of construction. Furthermore, it is to compare it with SWIFFT. Hash function is constructed based on the result of algebraic operations on modular polynomial ringwith . Modular polynomial ring noted as is a set of all polynomials of degree at most with coefficients in . can be represented as a set of integer vector of modulo in dimension . So, it is simple to implement in a computer. In vector operations, is lattice . Furthermore, alattice that is defined from certain polynomial ring is called ideal lattice. HLI hash function is consists of addition and multiplication algorithm in the ring. Addition algorithm consists of sumation operations of modulo and multiplication consists of multiplication operations of modulo . Generally, algorithm of HLI hash function consists of multiplication operations of modulo and addition operations of modulo . However, if the input is binary number then multiplication algorithm only consists of multiplication operation of modulo , so algorithm of HLI hash function consists of multiplication operations of modulo and addtion operations of modulo . An hash function is secured if it has two properties, i.e., one way and collision resistance. HLI hash function hash is one way, it is following the proof of Micciancio. It is has collision resistant because of polynomial is irreducible over and monic. Moreover, it is proved that for every unit vector , the vector is small vector. If the input of hash function is a binary number then HLI hash function only involves addition operations of modulo . So the time that used almost same with SWIFFT. The excellence of HLI hash function is the key size smaller than SWIFFT. This effect on
Keyword: hash function, modular polynomial ring, lattice