Overlay Protection Against Link Failures Using Network Coding

This paper introduces a network coding-based protection scheme against single and multiple link failures. The proposed strategy ensures that in a connection, each node receives two copies of the same data unit: one copy on the working circuit, and a second copy that can be extracted from linear combinations of data units transmitted on a shared protection path. This guarantees instantaneous recovery of data units upon the failure of a working circuit. The strategy can be implemented at an overlay layer, which makes its deployment simple and scalable. While the proposed strategy is similar in spirit to the work of Kamal '07 & '10, there are significant differences. In particular, it provides protection against multiple link failures. The new scheme is simpler, less expensive, and does not require the synchronization required by the original scheme. The sharing of the protection circuit by a number of connections is the key to the reduction of the cost of protection. The paper also conducts a comparison of the cost of the proposed scheme to the 1+1 and shared backup path protection (SBPP) strategies, and establishes the benefits of our strategy.Comment: 14 pages, 10 figures, accepted by IEEE/ACM Transactions on Networkin

Keragaman Dan Kelimpahan Sumberdaya Ikan Di Perairan Hutan Mangrove Pulau Unggas Air Bangis Pasaman Barat

Hutan mangrove merupakan ekosistem unik dan mempunyai tiga fungsi pokok yaitu ekologi, fisik dan ekonomi. Di kawasan perairan hutan bakau Pulau Unggas, Air Bangis, Pasaman Barat. Tujuan penelitian ini adalah untuk menentukan keragaman dan kelimpahan sumberdaya perikanan disekitar perairan Pulau Unggas. Alat dan bahan yang digunakan adalah metode survei dari 4 stasiun. Dari sampel ikan yang ditangkap menggunakan alat penangkap ikan monofilamen net dengan ukuran mata jaring 1,5 inchi dan panjang jaring 120 meter. Telah ditemui 7 suku dan 16 jenis ikan yang dominan adalah suku Lutjanidae 4 jenis dan 3 jenis pada suku Carangidae. Dari hasil analisis data didapat nilai indeks keanekaragam 0,452–0,970, kemerataan 0,620–0,950, kekayaan 0,565–1,820 dan kesamaan 0,50–1,334. Dari nilai distribusi alat penangkapan ikan tiap individu didapati nilai rata-rata 0,785

On some generalized ageing orderings

Some partial orderings which compare probability distributions with the expo- nential distribution, are found to be very useful to understand the phenomenon of ageing. Here, we introduce some new generalized partial orderings which de- scribe the same kind of characterization of some generalized ageing classes. We give some equivalent conditions for each of the orderings. Inter-relations among the generalized orderings have also been discussed