Dongyang Long
Sun Yat-sen University
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Publication
Featured researches published by Dongyang Long.
Applied Mathematical Modelling | 2003
Ming Li; Wei Zhao; Weijia Jia; Dongyang Long; Chi-Hung Chi
Abstract The approach to model autocorrelation functions of real-traffic traces in communication networks is presented based on optimal approximation in Hilbert space. The verifications are carried out with the real-traffic traces.
International Journal of Information Technology and Decision Making | 2003
Ming Li; Chi-Hung Chi; Weijia Jia; Wei Zhao; Wanlei Zhou; Jiannong Cao; Dongyang Long; Qiang Meng
There are two statistical decision making questions regarding statistically detecting sings of denial-of-service flooding attacks. One is how to represent the distributions of detection probability, false alarm probability and miss probability. The other is how to quantitatively express a decision region within which one may make a decision that has high detection probability, low false alarm probability and low miss probability. This paper gives the answers to the above questions. In addition, a case study is demonstrated.
Lecture Notes in Computer Science | 2004
Ming Li; Chi-Hung Chi; Dongyang Long
Detecting signs of distributed denial-of-service (DDOS) flood attacks based on traffic time series analysis needs characterizing traffic series using a statistical model. The essential thing about this model should consistently characterize various types of traffic (such as TCP, UDP, IP, and OTHER) in the same order of magnitude of modeling accuracy. Our previous work [1] uses fractional Gaussian noise (FGN) as a tool for featuring traffic series for the purpose of reliable detection of signs of DDOS flood attacks. As a supplement of [1], this article gives experimental investigations to show that FGN can yet be used for modeling autocorrelation functions of various types network traffic (TCP, UDP, IP, OTHER) consistently in the sense that the modeling accuracy (expressed by mean square error) is in the order of magnitude of 10− − 3.
international conference on algorithms and architectures for parallel processing | 2005
Dan Wu; Dongyang Long; Changji Wang; Zhanpeng Guan
A new approach to fight against Internet worms through the use the worm-killing worm has been presented. This paper attempts to model the interaction between the two worms using the divide-and-conquer strategy. We extends the idea of the killer-worm and divide it into three basic types. 1) Patching type: It only installs the patches on the susceptible machines; 2) Predator type: It only kills the worm (it may also patch the infected machines); 3) Composition type: It does both the jobs. The state transition diagram of the two worms and a mathematical model for every type are given. The results by dynamic simulation with the help of MATLAB are obtained.
international conference on information technology coding and computing | 2001
Dongyang Long; Weijia Jia
Novel maximal encoding, encoding, and maximal prefix encoding different from Huffman encoding are introduced. It is proven that for finite source alphabets all Huffman codes are optimal maximal codes, codes, and maximal prefix codes. Conversely, the above three types optimal codes need not to be the Huffman codes. Completely similar to Huffman codes, we prove that for every random variable with a countably infinite set of outcomes and with finite entropy there exists an optimal maximal code (code, maximal prefix code) which can be constructed from optimal maximal codes (codes, maximal prefix codes) for truncated versions of the random variable, and furthermore, that the average code word lengths of any sequence of optimal maximal codes (codes, maximal prefix codes) for the truncated versions converge to that of the optimal maximal code (cone, maximal prefix code).
parallel and distributed computing applications and technologies | 2004
Ming Li; Jingao Liu; Dongyang Long
Attentions are increasingly paid to reliable detection of intrusions as can be seen from [1, 2]. As a matter of fact, the challenge is to develop a system that detects close to 100 percent of attacks with minimal false positives. We are still far from achieving this goal [1, p. 28]. In this regard, our early work discusses a reliable approach regarding detection of signs of distributed denial-of-service (DDOS) attacks [3], where arrival time series of a protected site is specifically featured by autocorrelation function. As a supplementary to [3], this article specifically focuses on abstractly discussing probability principle involved in [3] such that the present probability principle of detection is flexible in practical applications. In addition to this, the selection of a threshold for a given detection probability is also given.
conference information and communication technology | 2002
Dongyang Long
Novel maximal coding compression techniques for the most important file-the text file of any full-text retrieval system are discussed in this paper. As a continuation of our previous work, we show that the optimal maximal coding schemes coincide with the optimal uniquely decodable coding schemes. An efficient algorithm generating an optimal maximal code (or an optimal uniquely decodable code) is also given. Similar to the Huffman codes, from the computational difficulty and the information-theoretic impossibility point of view, the problem of breaking an optimal maximal code is further investigated. Due to the Huffman code being a proper subclass of the optimal maximal code, which is good at applying to a large information retrieval system and consequently improving the system security.
International Journal of Computer Mathematics | 2003
Dongyang Long; Weijia Jia; Ming Li
Existence of the optimal prefix codes is shown in this paper. Relationship between the optimal prefix code and the Huffman code is also discussed. We prove that all Huffman codes are optimal prefix codes and conversely optimal prefix codes need not be Huffman codes. Especially, the problem of whether the optimal prefix code has to be maximal is presented. Although for information source alphabets of being not greater than four letters we show that an optimal prefix code must be maximal, it remains to be an open problem in general. As seen from Huffman codes, optimal prefix codes are used not only for statistical modeling but also for dictionary methods. Moreover, it is obtained that the complexity of breaking an optimal prefix code is NP-complete from the viewpoint of computational difficulty.
pacific rim conference on multimedia | 2001
Dongyang Long; Weijia Jia
Novel coding schemes are introduced and relationships between optimal codes and Huffman codes are discussed. It is shown that, for finite source alphabets, the Huffman coding is the optimal coding, and conversely the optimal coding needs not to be the Huffman coding. It is also proven that there always exists the optimal coding for infinite source alphabets. We show that for every random variable with a countable infinite set of outcomes and finite entropy there exists an optimal code constructed from optimal codes for truncated versions of the random variable. And the average code word lengths of any sequence of optimal codes for the truncated versions converge to that of the optimal code. Furthermore, a case study of data compression is given. Comparing with the Huffman coding, the optimal coding is a more flexible compression method used not only for statistical modeling but also for dictionary schemes.
network and parallel computing | 2004
Ming Li; Jingao Liu; Dongyang Long
Paxson and Floyd (IEEE/ACM T. Netw. 1995) remarked the limita- tion of fractional Gaussian noise (FGN)) in accurately modeling LRD network traffic series. Beran (1994) suggested developing a sufficient class of paramet- ric correlation form for modeling whole correlation structure of LRD series. M. Li (Electr. Letts., 2000) gave an empirical correlation form. This paper 1 extends Lis previous letter by analyzing it in Hilbert space and showing its flexibility in data modeling by comparing it with FGN (a commonly used traffic model). The verifications with real traffic suggest that the discussed correlation struc- ture can be used to flexibly model LRD traffic series.