Judul: Mempelajari Neraca Air Tanah Harian untuk Estimasi Besarnya ETc dan Kc Tanaman Teh di PTPN VII Perkebunan Gunung Mas Puncak, Jawa Barat
Abstrak: Didalam proses pertanian, air merupakan salah satu faktor terpenting. Kebutuhan air bagi tanaman sebagian besar dari air tanah yang diserap akar tanaman dan ditranspirasikan melalui daun (Suseno, 1974). Banyaknya air yang diperlukan tanaman tergantung antara lain pada jenis tanaman, fase pertumbuhan dan evapotranspirasi yang ada hubungannya dengan faktor lingkungan seperti iklim, kesuburan tanah dan kelembaban tanah (Richards dan Wedleich, 1952). Hubungan antara kandungan air tanah dan pertumbuhan tanaman antara lain dapat dikemukakan bahwa pertumbuhan tanaman dapat dipengaruhi oleh bertambahnya kekeringan setelah kapasitas lapang. Pada lapisan tanah atas kandungan air tanah akan berkurang karena evaporasi dan transpirasi yang sangat dipengaruhi oleh unsur-unsur klimatologi, jenis tanah dan kedalaman tanah.
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Judul: Kebutuhan air tanaman tebu dan hubungannya dengan pemberian air secara curah dan tetes
Abstrak: Tanaman tebu merupakan tanaman yang membutuhkan banyak air selama masa pertumbuhan vegetatifnya, tetapi tidak menyukai air yang berlebihan dan menginginkan kondisi air tanah rendah selama masa pemasakan. Kandungan air pada tanaman tebu yang berlebihan atau kekurangan akan menimbulkan gangguan fisiologis karena air merupakan salah satu faktor pembatas bagi pertumbuhan tanaman tebu. Penelitian ini bertujuan menentukan kebutuhan air tanaman tebu berdasarkan ketersediaan air hujan dan hubungannya dengan pemberian air secara curah dan tetes (studi kasus di PT. Gunung Madu Plantations, Lampung). Perhitungan kebutuhan air tanaman tebu dilakukan dengan metode radiasi sedangkan penentuan besarnya curah hujan efektif dengan metode USDA (1969). Menurut Doorenbos dan Kassam (1979), bila tidak tersedia air yang cukup bagi tanaman maka ETa < ETm dan hal ini akan mempengaruhi hasil. Pengaruhnya tergantung pada spesies tanaman, lama waktu terjadinya, besar tingkat kekurangan dan tingkat pertumbuhan tanaman pada saat itu. Perhitungan rata-rata ETa bulanan pada tanaman dapat diperoleh dengan menggunakan indeks ketersediaan air tanah atau ASI (Available Soil Water Index) ASI menunjukkan bagian dari bulan dimana ketersediaan air tanah cukup untuk memenuhi kebutuhan air tanaman (ETa = ETm). Kombinasi dari nilai ASI, ETm dan sisa ketersediaan air tanah ((1-p)Sa.D) memberikan besarnya ETa rata-rata harian. Tekstur tanah dilokasi penelitian adalah lempung berpasir dengan persentase kandungan pasir 60.37%, debu 31.77% dan liat 7.86%. Kadar air tanah tersedia 11.24% volume dengan kondisi pada kapasitas lapang (pF 2.54) 30.92% volume, pada titik layu permanen (pF 4.2) 19.68% volume, pada titik jenuh (pF 1) 37.34% volume dan pada pF 2 kadar air tanah sebesar 35.41% volume. ..
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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