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: Valuasi Sumberdaya Mangrove sebagai Pertimbangan dalam Upaya Rehabilitasi Ekosistem Mangrove di Muara Sungai Sesayap Kabupaten Tana Tidung.
Abstrak: Mangrove mempunyai jasa ekosistem yang bernilai ekonomi. Manfaat mangrove dapat dirasakan secara langsung dan tidak langsung. Pengelolaan mangrove menjadi perhatian penting seiring terjadinya penurunan mangrove akibat konversi lahan. Penelitian ini bertujuan untuk mengidentifikasi dan menghitung nilai ekonomi sumberdaya ekosistem mangrove, serta efektivitas tingkat rehabilitasi untuk bahan pertimbangan dalam pengelolaan ekosistem mangrove di muara Sungai Sesayap, Kabupaten Tana Tidung. Metode yang digunakan pada penelitian ini adalah analisis kuantitaif yaitu analisis effort of production dan benefit transfer. Ekosistem mangrove di muara Sungai Sesayap dalam satu dekade ini telah terjadi penurunan luasan sebesar 30,15%. Nilai ekonomi total (NET) ekosistem mangrove di muara Sungai Sesayap sebesar Rp 204.778.669/ha/tahun. Nilai efektivitas rehabilitasi ekosistem mangrove di daerah rehabilitasi muara Sungai Sesayap mencapai 50,45%. Nilai efektivitas rehabilitasi menunjukan efektif dan dapat menjadi bahan pertimbangan bagi perencanaan penganggaran (budgeting) dalam mengelola ekosistem mangrove.
Keyword: ekonomi sumberdaya, mangrove, valuasi, rehabilitasi

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