Judul: Struktur Komunitas Makrozoobentos di Perairan Kali Baru Kodya Bengkulu
Abstrak: Penelitian bertujuan untuk mengetahui struktur kornunitas makrozoobentos akibat beban rnasukan bahan organik dari kegiatan yang berbeda. Penelitian dilaksanakan bulan Maret sarnpai Mei 1998, di perairan Kali Baru Kodya Bengkulu. Penentuan stasiun pengarnatan di dasarkan atas perbedaan beban rnasukan dari aktivitas rnanusia. Stasiun A (aktivitas: industri periknan, pernukirnan, dan pelabuhan perikanan), stasiun B (aktivitas: di tarnbak), dan stasiun C (tidak ada aktivitas manusia yang menonjol). Pengarnbilan sarnpel rnakrozoobentos, air dan substrat dilakukan sebanyak 7 (tujuh) kali, pada waktu surut.
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Judul: Struktur komunitas makrrozoobenthos sebagai indikator perubahan kualitas perairan di Kali Surabaya
Abstrak: Seiring meningkatnya laju pertumbuhan penduduk dan aktivitas pembangunan di segala sektor, menyebabkan produksi limbah industri dan domestik akan semakin meningkat. Hal ini tentunya berpengaruh terhadap kondisi Kali Surabaya. Perubahan kondisi perairan sungai akibat beban masukan limbah menyebabkan menghilangnya beberapa organisme diantaranya makrozoobenthos. Penelitian ini bertujuan untuk mempelajari kondisi perairan Kali Surabaya, dengan mengetahui struktur komunitas makrozoobenthos dan kemungkinan adanya gangguan seperti pencemaran perairan terhadap komunitas makrozoobenthos melalui penerapan Kurva Perbandingan Kelimpahan-Biomas (Kurva ABC). Penelitian dilakukan di ruas-ruas Kali Surabaya sepanjang kurang lebih 37 km pada bulan April sampai Mei 1998. Stasiun penelitian ditentukan secara sistematik. Lokasi penelitian dibagi menjadi sebelas stasiun pengamatan. Untuk mengetahuI kondisi struktur komunitas makrozoobenthos maka dilakukan analisis komposisi, kepadatan, indeks keanekaragaman, indeks keseragaman dan indeks dominansi. Tingkat pencemaran perairan diduga dengan analisis Kurva ABC (Abundance and Biomass Comparisson) dan lndeks Mutu Lingkungan (IML) perairan. Makrozoobenthos yang didapatkan di lokasi penelitian terdiri alas empat kelas yaitu Gastropoda, Pelecypoda, Oligochaeta dan Diptera. Komposisi makrozoobenthos yang didapatkan mengalami perubahan yang ekstrim dengan komposisi kelas Oligochaeta merupakan kelas biota yang dominan. Kepadatan makrozoobenthos mengalami variasi dari St. I (hulu) menuju St. XI (hilir). Nilai indeks keanekaragaman menunjukkan keanekaragaman yang rendah kecuali pada St. Ill, IV dan VIII. Nilai indeks keseragaman juga menunjukkan nilai yang cukup bervariasi kecuali pada St. I dan XI hanya didapatkan satu jenis. Sedangkan nilai indeks dominansi sebagian besar mendekati nilai 1, dengan demikian hampir semua stasiun pengamatan terjadi dominansi organisme. Berdasarkan nilai-nilai indeks tersebut maka diperkirakan ruas-ruas kali Surabaya mengalami gangguan lingkungan berupa pencemaran. Hasil analisis perbandingan kelimpahan-biomass (Kurva ABC) menunjukkan bahwa perairan Kali Surabaya sebagian besar telah tercemar, kecuali St. VII termasuk dalam kriteria agak tercemar.
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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