http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/99 2026-05-17T10:14:11Z 2026-05-17T10:14:11Z Vinh, Trong Le http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/973 2011-04-20T04:52:59Z 2007-01-01T00:00:00Z

Title: GA-based dynamic survivable routing in WDM optical networks with shared backup paths Authors: Vinh, Trong Le Abstract: This paper considers the problem of dynamic survivable routing in WDM networks with single link failure model. This work mainly concerns in how to dynamically determine a protection cycle (i.e., two link-disjoint paths between a node pair) to establish a dependable lightpath with backup paths sharing. The problem is identified as NP-complete, thus a heuristic for finding near optimal solution with reasonable computation time is usually preferred. Inspired from the principle of genetic algorithms (GA), a GA-based survivable routing algorithm for the problem with a new fitness function, which allows us to improve blocking performance, will be proposed. Extensive simulation results upon the ns-2 network simulator and two typical network topologies show that our algorithm can achieve a significantly lower blocking probability than conventional algorithms. Description: VNU Journal of Science, Mathematics - Physics. Vol. 23 (2007), No 2, P. 122-130

2007-01-01T00:00:00Z Hoang, Chi Thanh http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/964 2011-04-20T04:49:24Z 2007-01-01T00:00:00Z

Title: Some methods for transforming sequential processes into concurrent ones Authors: Hoang, Chi Thanh Abstract: In this paper we investigate and build up three methods for transforming sequential processes of a net system into concurrent ones. These methods are based on: trace languages, shiftleft and case graphs. They are also presented by detail algorithms and can be applied to other models of concurrent systems. Description: VNU Journal of Science, Mathematics - Physics. Vol. 23 (2007), No 2, P. 113-121

2007-01-01T00:00:00Z Le, Van Ngoc Nguyen, Thi Thanh Huyen Nguyen, Hao Quang http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/958 2011-04-20T04:46:26Z 2007-01-01T00:00:00Z

Title: Study on Monte-Carlo calculation of peak efficiencies of the superpure Hp Ge detector (Gmx) in environmental gamma spectrometry with using MCNP4C2 Authors: Le, Van Ngoc; Nguyen, Thi Thanh Huyen; Nguyen, Hao Quang Abstract: Monte-Carlo modeling allows calculating the detector efficiency in gamma spectrometry of environmental samples with taking into consideration both the photon selfabsorption in sample itself and absorption in all other materials between the sample and the detector’s active part. In this paper, the peak efficiencies of the Hp Ge detector (GMX) for gammas at various energies (emitted isotropically from the standard disk source and volumetric source - environmental sample, in which the different radionuclides are present) are calculated based on MCNP4C2-Monte-Carlo multi-purpose radiation transport code system developed in the Los-Alamos laboratory, U.S.A. The obtained calculating results are compared with the experimentally measured data and a good agreement between them is shown out. Description: VNU Journal of Science, Mathematics - Physics. Vol. 23 (2007), No 2, P. 99-104

2007-01-01T00:00:00Z Trinh, Thi Loan Le, Hong Ha Nguyen, Ngoc Long http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/951 2011-04-20T04:42:36Z 2007-01-01T00:00:00Z

Title: Optical transition of Eu3+ in Mg(Al1-x Eux)2O4 Authors: Trinh, Thi Loan; Le, Hong Ha; Nguyen, Ngoc Long Abstract: The powders of Mg(Al1-xEux)2O4 have been synthesized by sol-gel method. Optical properties of the material were investigated. The nature of lines in luminescence spectra is related to the electron transitions of Eu3+ ions corresponding to different sites in the lattice. The influence of Eu concentration on optical spectra was studied. Description: VNU Journal of Science, Mathematics - Physics. Vol. 23 (2007), No 2, P. 84-91

2007-01-01T00:00:00Z