A TCAM-based solution for integrated traffic anomaly detection and policy filtering

The survivability of the future Internet is largely dependent on whether it will be able to successfully address both security and performance issues facing the Internet. On one hand, the Internet becomes more and more vulnerable due to fast spreading malicious attacks. On the other hand, it is under great stress to meet ever growing/changing application demands while having to sustain multi-gigabit forwarding performance. In this paper, we propose a Ternary Content Addressable Memory (TCAM) coprocessor based solution for high speed, integrated TCP flow anomaly detection and policy filtering. The attacking packets with spoofed source IP addresses are detected through two-dimensional (2D) matching. The key features of the solution are: (1) setting flag bits in TCAM action code to support various packet treatments; (2) managing TCP flow state in pair to do 2D matching. We evaluate the solution’s ability to detect TCP-based flooding attacks based on real-world-trace simulations. The results show that the proposed solution can match up OC-192 line rate. The possible modifications of the solution for the detection of low rate TCP-targeted attacks are also discussed.     

The design and implementation of a session layer for delay-tolerant networks

The DTN architecture is based around sender-initiated unicast communication that is insufficient or inconvenient to meet the needs of many applications. To address these limitations, we define a DTN session layer and associated extensions to the DTN bundle protocol that more naturally support receiver-driven applications and multicast communication. Within a session, we provide mechanisms allowing applications to convey ordering relationships between successive transmissions that can be used by the network to help ensure a distributed application’s delivery ordering expectations are met. We also extend the bundle protocol’s expiration procedures to support more efficient network utilization by allowing in-network deletion of obsolete messages. We present the design rationale and describe our implementation of these mechanisms and discuss their advantages in meeting the needs of several popular types of applications.     

Partial 3D Shape Retrieval by Reeb Pattern Unfolding

This paper presents a novel approach for fast and efficient partial shape retrieval on a collection of 3D shapes. Each shape is represented by a Reeb graph associated with geometrical signatures. Partial similarity between two shapes is evaluated by computing a variant of their maximum common sub-graph.
By investigating Reeb graph theory, we take advantage of its intrinsic properties at two levels. First, we show that the segmentation of a shape by a Reeb graph provides charts with disk or annulus topology only. This topology control enables the computation of concise and efficient sub-part geometrical signatures based on parameterisation techniques. Secondly, we introduce the notion of Reeb pattern on a Reeb graph along with its structural signature. We show this information discards Reeb graph structural distortion and still depicts the topology of the related sub-parts. The number of combinations to evaluate in the matching process is then dramatically reduced by only considering the combinations of topology equivalent Reeb patterns.
The proposed framework is invariant against rigid transformations and robust against non-rigid transformations and surface noise. It queries the collection in interactive time (from 4 to 30 seconds for the largest queries). It outperforms the competing methods of the SHREC 2007 contest in term of NDCG vector and provides, respectively, a gain of 14.1% and 40.9% on the approaches by Biasotti et al. [ BMSF06 ] and Cornea et al. [ CDS*05 ].
As an application, we present an intelligent modelling-by-example system which enables a novice user to rapidly create new 3D shapes by composing shapes of a collection having similar sub-parts.     

Design and analysis of robust fault detection filter using LMI tools

In this paper, the robust fault detection filter design problem for linear time invariant (LTI) systems with unknown inputs and modeling uncertainties is studied. The basic idea of our study is to formulate the robust fault detection filter design as a H_∞ model-matching problem. A solution of the optimal problem is then presented via a linear matrix inequality (LMI) formulation. The main results include the formulation of robust fault detection filter design problems, the derivation of a sufficient condition for the existence of a robust fault detection filter and construction of a robust fault detection filter based on the iterative of LMI algorithm.     

Benchmarking Image Segmentation Algorithms

We present a thorough quantitative evaluation of four image segmentation algorithms on images from the Berkeley Segmentation Database. The algorithms are evaluated using an efficient algorithm for computing precision and recall with regard to human ground-truth boundaries. We test each segmentation method over a representative set of input parameters, and present tuning curves that fully characterize algorithm performance over the complete image database. We complement the evaluation on the BSD with segmentation results on synthetic images. The results reported here provide a useful benchmark for current and future research efforts in image segmentation.     

A new process for fabricating tip-shaped polymer microstructure array with patterned metallic coatings

In this paper, we present a new process for fabricating tip-shaped polymer microstructure array coated by patterned metal layer. This new process involves three techniques including: micro-molding, patterned metal layer transfer, and electrochemical-based sacrificial layer. As we know, it is very difficult to remove the extra photoresist (PR) in the concave areas in traditional micro-fabrication technology, which hinders patterning metal layers on three-dimensional (3D) microstructures. The electrochemical-based sacrificial layer technique can effectively resolve this problem, which is verified by scanning electron microscopy (SEM) characterization. Comparative study between the 3D metal-coated polyimide microstructures fabricated with and without the electrochemical-based sacrificial layer step is also performed and SEM images proved the effect of the presented process. The applicability of the developed process is also demonstrated with the successful fabrication of a pyramid-shaped polyimide microelectrodes array for neural stimulation.     

An efficient image-mosaicing method based on multifeature matching

Mosaicing is connecting two or more images and making a new wide area image with no visible seam-lines. Several algorithms have been proposed to construct mosaics from image sequence where the camera motion is more or less complex. Most of these methods are based either on the interest points matching or on theoretical corner models. This paper describes a fully automated image-mosaicing method based on the regions and the Harris points primitives. Indeed, in order to limit the search window of potential homologous points, for each point of interest, regions segmentation and matching steps are being performed. This enables us to improve the reliability and the robustness of the Harris points matching process by estimating the camera motion. The main originality of the proposed system resides in the preliminary manipulation of regions matching, thus making it possible to estimate the rotation, the translation and the scale factor between two successive images of the input sequence. This estimation allows an initial alignment of the images along with the framing of the interest points search window, and therefore reducing considerably the complexity of the interest points matching algorithm. Then, the resolution of a minimization problem, altogether considering the couples of matched-points, permits us to perform the homography. In order to improve the mosaic continuity around junctions, radiometric corrections are applied. The validity of the herewith described method is illustrated by being tested on several sequences of complex and challenging images captured from real-world indoor and outdoor scenes. These simulations proved the validity of the proposed method against camera motions, illumination variations, acquirement conditions, moving objects and image noise. To determine the importance of the regions matching stage in motion estimation, as well as for the framing of the search window associated to a point of interest, we compared the matching points results of this described method with those produced using the zero-mean normalized cross correlation score (without regions matching). We made this comparison in the case of a simple motion (without the presence of a rotation around optical axis and/or a scale factor), in the case of a rotation and in the general case of an homothety. For justifying the effectiveness of this method, we proposed an objective assessment by defining a reconstruction error.

基于模式驱动和模糊查询的模式发现方法

在蛋白质序列的比对研究中,拥有相似模式的蛋白质常常具有相似的功能.通过已知的蛋白质序列模式可以很方便地对新蛋白质序列的功能结构进行研究和确认.蛋白质序列的发现已成为一个很有意义的题目.对基于模式驱动Pratt算法进行改进以提高其效率,在原来基础上引入模糊查询方法,能够更为快捷地从互不相关的蛋白质序列集合中找出最具代表性的蛋白质模式.     

深层网查询接口的自动集成

深层网数据库的访问方式主要是通过查询接口,所以查询接口是外部访问深层网数据库的门户.为了能够同时访问同一领域多个Web数据库,需要对多个Web数据库的查询接口进行集成.因此,提出基于本体的深层网查询接口集成方法.首先构建领域核心本体,在模式匹配过程中,不断完善核心本体;然后,以本体作为媒介,在不同查询接口模式间建立属性映射关系,发现属性间的语义关联;最后,根据本体概念出现的频数生成集成接口.实验表明提出的深层网查询接口自动集成方法是可行的和高效的.