Judul: Kondisi tata Air Sub Das Progo Hulu Kabupaten Temanggung Propinsi Jawa Tengah
Abstrak: Penelitian ini bertujuan untuk mengetahui perilaku tata air (fluktuasi debit dan kualitas air) Sub DAS Progo Hulu dan permasalahannya (erosi, sedimentasi, kesesuaian pemanfaatan lahan dengan fungsinya, tekanan penduduk, pendapatan/sumber pendapatan penduduk dan pemahaman terhadap upaya-upaya konservasi tanah dan air), serta sampai sejauh mana upaya-upaya rehabilitasi lahan dan konservasi tanah yang dilakukan untuk mengatasi permasalahan yang ada tersebut. Kesemuanya ini bisa menjadi indikator dari pengelolaan Sub DAS Progo Hulu tersebut.
Keyword: tata air

Judul: Kondisi tata air dan penutupan lahan di das Ciliwung Jawa Barat
Abstrak: Air adalah sumberdaya alam fisik yang mutlak diperlukan bagi hidup dan kehidupan makhluk hidup di muka bumi ini. Walaupun air dapat dijumpai dimana- mana dan merupakan kekayaan alam yang dapat kembali melalui siklus hidrologi, namun distribusi dan bentuk air terbatas. Daerah aliran sungai (DAS) adalah suatu wilayah yang menampung dan menyimpan air hujan. DAS juga merupakan suatu ekosistem dimana terdapat hubungan timbal-balik antara komponennya, diantaranya sumber daya tanah, vegetasi dan air sebagai obyek dan manusia sebagai subyek. Pengaturan tataguna lahan berpengaruh terhadap sistem hidrologi dalam ekosistem DAS. Hal ini terkadang secara tidak langsung dapat mengganggu kelestarian sumber daya alam di dalam DAS itu sendiri. Penelitian ini bertujuan untuk melihat dan menduga kondisi tata air (fluktuasi debit) di Sub. DAS Ciliwung Hulu dan Tengah yang berhubungan dengan perubahan tataguna lahan. Data yang diperlukan dalam hal ini adalah data curah hujan, debit Sungai Ciliwung dan penggunaan lahan selama periode tahun 1984-1995. Pada Sub. DAS Ciliwung Hulu curah hujan rata-rata bulanan tertinggi terjadi pada bulan Januari sebesar 527 mm dan terkecil pada bulan Juli sebesar 137 mm. Sedangkan debit sungai tertinggi terjadi pada bulan Februari sebesar 35,55 m³/dt dan debit sungai terkecil terjadi pada bulan Agustus sebesar 6,52 m²³/dt. Pada dasarnya perubahan curah hujan diikuti pula oleh perubahan debit sungai, jadi diantara keduanya terdapat hubungan yang erat. Selama periode tahun 1984-1995 terjadi perubahan penggunaan lahan di Sub. DAS Ciliwung Hulu. Dari perubahan penggunaan lahan mengakibatkan perubahan kemampuan lahan dalam meresapkan air. Kemampuan lahan banyak meresapkan air...
Keyword: 

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