Judul: Pengaruh penutupan vegetasi pantai terhadap kemungkinan intrusi air laut di pesisir pantai Pangandaran
Abstrak: Pengaruh penutupan tanah oleh vegetasi terhadap kuantitas dan kualitas air telah sering dibicarakan orang namun yang khusus menyangkut intrusi air laut masih sangat terbatas. Selain itu, daerah-daerah pesisir sering merupakan daerah yang tidak memiliki sumber air yang layak disebabkan telah terjadinya proses intrusi. Penelitian ini bertujuan untuk mengetahui bagaimana pengaruh penutupan vegetasi pantai terhadap intrusi dan apakah intrusi telah terjadi di Pantai Pangandaran. Pengambilan contoh air dilakukan di Pangandaran pada dua kondisi penutupan vegetasi, yaitu bervegetasi (A1) dan tanpa vegetasi (A2). Penutupan vegetasi pada A₁ yang ditemui di lokasi penelitian adalah berupa hutan pantai sekunder tua yang didominasi oleh jenis-jenis Laban (Vitex pubescens), Kisegel (Dillenia exellsa), dan Marong (Cratoxylon formosum). Sedangkan pada penutupan A2 berupa perumahan penduduk yang rapat. Model yang digunakan dalam penelitian ini adalah analisis faktorial 2 x 3 dengan 3 ulangan.
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Judul: Pengaruh Berbagai Penutupan Lahan Terhadap Tingkat Erosi dan Aliran Permukaan (Studi Kasus di RPH Tanggulun, BKPH Kalijati, KPH Purwakarta)
Abstrak: Vegetasi penutup tanah sangat penting. Vegetasi berperan dalam memberi naungan, memperlunak suhu ekstrim, menghambat angin, debu dan suara, rnengintersepsi hujan, rnengurangi nm off, meningkatkan kelembaban dan menghambat erosi serta pengeringan permukaan (Lee, 1988). Vegetasi penutup tanah yang berbeda akan menghasilkan Iimpasan permukaan dan erosi yang berbeda, dimana vegetasi penutup tanah yang lebih baik akan memperkecil fluktuasi aliran permukaan dan erosi. Semakin rapat atau banyaknya vegetasi penutupan lahan maka semakin efektif pengaruh vegetasi dalam melindungi permukaan tanah dan ancaman erosi.
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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