Entity

Time filter

Source Type

Vietnam, China

Minh Hau T.,Kunming University of Science and Technology | Minh Hau T.,Tuyhoa Industrial College | Yu X.,Kunming University of Science and Technology | Zhou D.,Kunming University of Science and Technology | And 4 more authors.
Optical Materials | Year: 2013

The Bi-Er co-doped lanthanum aluminosilicate glasses, which exhibited a broadband near-infrared emission, were developed and observed in using the optical absorption and photoluminescence spectra. A super broadband near-infrared emission extending from 1.0 to 1.8 μm with a full-width at half-maximum of 450 nm which covered the whole O, E, S, C and L bands, was observed in Bi-Er co-doped samples under 808 nm excitation, as a result of the overlap of the Bi-related emission band (1270 nm) and the emission from Er 3+ 4I13/2 → 4I15/2 transition (1545 nm). This report will discuss about a possible mechanism for energy transfer between Bi-related centers and Er3+ ion. © 2012 Elsevier B.V. All rights reserved. Source


Truong D.-T.,Nanjing Southeast University | Truong D.-T.,A+ Network | Truong D.-T.,Tuyhoa Industrial College | Cheng G.,Nanjing Southeast University | And 7 more authors.
Journal of Internet Technology | Year: 2016

Modern botnets such as Zeus, Conficker have started employing a technique called domain fluxing to prevent a naive blacklisting approach employed by network administrators. Domain fluxing bots generate a list of Pseudo-Random Domain names (PRD) or base on a predefined algorithm, called Domain name Generation Algorithm (DGA) for botnet operators to command and control (C&C) their bots. It is a pressing issue today to prevent or least reduce their destructive actions. In this paper, we focus on detecting domain-flux botnet within the monitored network based on DNS traffic features. First, we present a method to identify bot-infected machines based on the similar periodic time intervals series of DNS queries. Then, in order to detect C&C Server, we monitor the stream of active DNS queries from bot-infected machines, and introduce a method to extract related feature values aiming to distinguish bot-generated domain names from humangenerated ones base on a classifier model that we previously trained. We use five various machine learning algorithms to train classifier models and evaluate the effectiveness of detection. The experimental results showed that the proposed method achieves the highest detection efficiency for decision trees algorithms (J48) with the average overall accuracy up to 98.5% and false positive rate is 1.2%. Source


Minh Hau T.,Kunming University of Science and Technology | Minh Hau T.,Tuyhoa Industrial College | Wang R.,Kunming University of Science and Technology | Yu X.,Kunming University of Science and Technology | And 5 more authors.
Journal of Physics and Chemistry of Solids | Year: 2012

The Bi-Tm-Er co-doped SiO 2-Al 2O 3-La 2O 3 (SAL) glasses, which exhibited a broadband near-infrared (NIR) emission, were investigated by the optical absorption and photoluminescence spectra. A super broadband NIR emission extending from 0.95 to 1.6 μm with a full-width at half-maximum (FWHM) of 430 nm which covered the whole O, E, S, C and L bands, was observed in Bi-Tm-Er co-doped samples under 808 nm excitation, as a result of the overlap of the Bi-related emission band (centered at 1270 nm) and the emission from Tm 3+ 3H 4→ 3F 4 transition (1450 nm) as well as Er 3+ 4I 13/2→ 4I 15/2 transition (1545 nm). In addition, a super broadband emission with amplitude relatively flat from 0.95 to 2.1 μm has been observed. The possible energy transfer between Bi-related centers, Tm 3+ ions and Er 3+ ions was proposed. © 2012 Elsevier Ltd. All rights reserved. Source


Tuan B.M.,Nanjing Southeast University | Tuan B.M.,Tuyhoa Industrial College | Chen Y.,Nanjing Southeast University
Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) | Year: 2014

The stress intensity factor (SIF) and stress fields at the crack tips of a center crack and an edge crack are investigated by the finite element method (FEM) and the nodal displacement method. With the use of the 8 node isoparametric quadrilateral element and the quarter singular element, the influence of meshing density and crack length on the calculation accuracy is studied. The nodal density in sub-region around the crack tips is improved, which can ensure the calculation accuracy and save computing time. The code for calculating and analyzing stress intensity factor, stress fields and displacement fields at the crack tips for mode I and mode II SIFs of plate is written in Matlab/Simulink. The results of the FEM-code are compared with those of the exact methods. The results show that this proposed method can improve the calculation accuracy and the converging speed. The algorithm is reasonable and the results can be used to improve the precision of simulation results and guide engineering design. Source


Tu T.D.,Nanjing Southeast University | Tu T.D.,A+ Network | Tu T.D.,Tuyhoa Industrial College | Guang C.,Nanjing Southeast University | And 3 more authors.
2015 International Conference on Computing, Management and Telecommunications, ComManTel 2015 | Year: 2015

Modern botnets such as Zeus and Conficker com-monly utilize a technique called domain fluxing or a Domain Generation Algorithm (DGA) to generate a large number of pseudo-random domain names dynamically for botnet operators to control their bots. These botnets are becoming one of the most serious threats to the Internet security on a global scale. In this paper, we present a method based on analyzing the similar peri-odic time intervals series of DNS queries to identify DGA-bot infected machines. This method passively captures all DNS traffic from the gateway of monitor network. Firstly, we group queries of the same domain name that is requested by hosts, and then extracts time interval series between adjacent queries. Secondly, we measure the similar periodicity of DNS queries by calculating the squared Euclidean distance between each pair of their time interval series. Finally, we apply a hierarchical clustering algo-rithm to cluster high similar domain names. The experiment re-sults show that the domain names are generated by the same botnet or DGA would be grouped into the same cluster, thus all of the hosts that query to these clusters are marked as compro-mised hosts running a domain-flux botnet within monitor net-work. © 2015 IEEE. Source

Discover hidden collaborations