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Polynomial-time hierarchy of computable reals

Journal of Computational Information Systems 2011年第4期7卷 1108-1115页

作者： Chen, Qingliang Su, Kaile Wu, Lijun Department of Computer Science Jinan University Guangzhou 510632 China Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University Shanghai China Key Laboratory of High Confidence Software Technologies Ministry of Education Peking University Beijing China Institute for Integrated and Intelligent Systems Griffith University Brisbane Australia School of Computer Science and Engineering University of Electronic Science and Technology Chengdu 610054 China

In mathematics, various representations of real numbers have been investigated and all these representations are proved to be mathematically equivalent. Furthermore, it is known that all effective versions of these representations lead to the same class of "computable real numbers". However, when subrecursive (such as primitive recursive) is taken into account, these representations can lead to different notions of "computable real numbers". This paper will look into the polynomial-time version of the problem for computable real numbers under different representations. We will summarize the known results to exhibit the comprehensive hierarchy they form. Our goal is to clarify systematically how the polynomial-time computability depends on the representations of the real numbers. Copyright © 2011 Binary Information Press.

关键词： Polynomial approximation

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Directional diagnosis for wireless sensor networks

Directional diagnosis for wireless sensor networks

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International Conference on Distributed Computing in Sensor Systems (DCOSS)

作者： Wei Gong Kebin Liu Yunhao Liu Xibin Zhao Ming Gu Tsinghua University Beijing Beijing CN Department of Computer Science Hong Kong University of Science and Technology Hong Kong China Key Laboratory of Information System Security of Ministry of Education TNLIST School of Software Tsinghua University China

Network diagnosis is crucial in managing a wireless sensor network (WSN) since many network-related faults, such as node and link failures, can easily happen. Diagnosis tools usually consist of two key components, information collection and root-cause deduction, while in most cases information collection process is independent with root-cause deduction. This results in either redundant information which might pose high communication burden on WSNs, or incomplete information for root-cause inference that leads false judgments. To address the issue, we propose DID, a directional diagnosis approach, in which the diagnosis information acquirement is guided by the fault inference process. Through several rounds of incremental information probing and fault reasoning, root causes of the network abnormalities with high credibility are deduced. We employ a node tracing scheme to reconstruct the topical topology of faulty regions and build the inference model accordingly. We implement the DID approach in our forest monitoring sensor network system, GreenOrbs. Experimental results validate the scalability and effectiveness of this design.

关键词： Network topology Probes Topology Wireless sensor networks Sensors Relays Probabilistic logic

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RASS: A real-time, accurate and scalable system for tracking transceiver-free objects

RASS: A real-time, accurate and scalable system for tracking...

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IEEE International Conference on Pervasive Computing and Communications (PerCom)

作者： Dian Zhang Yunhuai Liu Lionel M. Ni College of Software Shenzhen University China Department of Computer Science and Engineering Hong Kong University of Science and Technology Hong Kong China Shenzhen Institutes of Advanced Technology Chinese Academy and Sciences China Shanghai Key Laboratory of Scalable Computing and Systems Shanghai Jiaotong University China

Transceiver-free object tracking is to trace a moving object without carrying any communication device in an environment where the environment is pre-deployed with some monitoring nodes. Among all the tracking technologies, RF-based technology is an emerging research field facing many challenges. Although we proposed the original idea, until now there is no method achieving scalability without sacrificing latency and accuracy. In this paper, we put forward a real-time tracking system RASS, which can achieve this goal and is promising in the applications like the safeguard system. Our basic idea is to divide the tracking field into different areas, with adjacent areas using different communication channels. So the interference among different areas can be prevented. For each area, three communicating nodes are deployed on the ceiling as a regular triangle to monitor this area. In each triangle area, we use a Support Vector Regression (SVR) model to locate the object. This model simulates the relationship between the signal dynamics caused by the object and the object position. It not only considers the ideal case of signal dynamics caused by the object, but also utilizes their irregular information. As a result it can reach the tracking accuracy to around 1m by just using three nodes in a triangle area with 4m in each side. The experiments show that the tracking latency of the proposed RASS system is bounded by only about 0.26s. Our system scales well to a large deployment field without sacrificing the latency and accuracy.

关键词： Accuracy Wireless communication Wireless sensor networks Interference Lead Synchronization Predictive models

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Strong Barrier Coverage Using Directional Sensors with Arbitrarily Tunable Orientations

Strong Barrier Coverage Using Directional Sensors with Arbit...

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International Conference on Mobile Ad-hoc and Sensor Networks, MSN

作者： Dan Tao Xu-Fei Mao Shao-Jie Tang Hai-Tao Zhang Hua-Dong Ma Hai-Jiang Xie School of Electronic and Information Engineering Beijing Jiaotong University Beijing China Beijing Key Laboratory of Intelligent Telecommunication Software and Multimedia Beijing University슠of Posts and슠Telecommunications Beijing China Department of Computer Science Illinois Institute of Technology Chicago IL USA Department of Computer Science and Technology XiAn JiaoTong University XiAn China

Barrier coverage is an important problem for sensor networks to fulfill some given sensing tasks. Barrier coverage guarantees the detection of events happened crossing a barrier of sensors. In majority study of barrier coverage using sensor networks, sensors are assumed to have an isotropic sensing model. However, in many applications such as monitoring an area using video camera, the sensors have directional sensing model. In this paper, we investigate strong barrier coverage using directional sensors, where sensors have arbitrarily tunable orientations to provide good coverage. We investigate the problem of finding appropriate orientations of directional sensors such that they can provide strong barrier coverage. By exploiting geographical relations among directional sensors and deployment region boundaries, we first introduce the concept of virtual node to reduce the solution space from continuous domain to discrete domain. We then construct a directional barrier graph (DBG) to model this barrier coverage question such that we can quickly answer whether there are directional sensors' orientations that can provide strong barrier coverage over a given belt region. If the belt region is strong barrier covered, we then develop energy-efficient solutions to find strong barrier path(s) that will approximately minimize the total or the maximum rotation angles of all directional sensors. Extensive simulations are conducted to verify the effectiveness of our solution.

关键词： Sensors Belts Clocks Numerical models Educational institutions Cameras Complexity theory

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Extracting Semantic Subgraphs to Capture the Real Meanings of Ontology Elements

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Tsinghua science and technology 2010年第6期15卷 724-733页

作者：汪鹏徐宝文周毓明 School of Computer Science and Engineering Southeast University State Key Laboratory for Novel Software Technology Nanjing University Department of Computer Science and Technology Nanjing University

An element may have heterogeneous semantic interpretations in different ontologies. Therefore, understanding the real local meanings of elements is very useful for ontology operations such as querying and reasoning, which are the foundations for many applications including semantic searching, ontology matching, and linked data analysis. However, since different ontologies have different preferences to describe their elements, obtaining the semantic context of an element is an open problem. A semantic subgraph was proposed to capture the real meanings of ontology elements. To extract the semantic subgraphs, a hybrid ontology graph is used to represent the semantic relations between elements. An extracting algorithm based on an electrical circuit model is then used with new conductivity calculation rules to improve the quality of the semantic subgraphs. The evaluation results show that the semantic subgraphs properly capture the local meanings of elements. Ontology matching based on semantic subgraphs also demonstrates that the semantic subgraph is a promising technique for ontology applications.

关键词： ontology ontology graph semantic subgraph ontology matching

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The integration of skin color segmentation and self-adapted template matching for the robust face detection

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International Review on computers and software 2011年第5期6卷 795-805页

作者： Zhiwen, Wang Shao-Zi, Li Ying, Dai Cognitive Science Department Xiamen University Xiamen 361005 China Department of Computer and Engineering Guangxi University of Technology Liuzhou 545006 China Fujian Key Laboratory of the Brain-like Intelligent Systems Xiamen University Xiamen 361005 China Faculty of Software and Info. Science Iwate Pref. University Iwate Japan

In this paper, an approach of integrating skin color segmentation and self-adapted template matching for the robust face detection is proposed. According to the clustering properties of the skin color of human faces in the YCbCr color space, the regions which close to the skin color are separated from the image by using Gaussian mixture model in order to achieve the purpose of rapidly detecting the external face. The influence of the brightness on the detection of the human faces is eliminated by using the illumination compensation technology, and also the confusion of the regions with the closed skin color with the human face is overcome by the adaptive template matching. Computation in the matching process is reduced by using the second matching algorithm. Experimental results show that proposed method can rapidly detect the human faces from a variety of images, while those detected faces include several of facial images with the different sizes, poses, races under the different illumination conditions. © 2011 Praise Worthy Prize S.r.l. - All rights reserved.

关键词： Template matching

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Breakdown voltage enhancement for power AlGaN/GaN HEMTs with Air-bridge Field Plate

Breakdown voltage enhancement for power AlGaN/GaN HEMTs with...

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IEEE Conference on Electron Devices and Solid-state Circuits

作者： Gang Xie Edward Xu Junmin Lee Niloufar Hashemi Fred Y. Fu Bo Zhang W.T. Ng State key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology Chengdu China The Edward S. Rogers Sr. Department of Electrical and Computer Engineering University of Toronto Toronto ONT Canada Crosslight software Inc. Burnaby BC Canada

This paper presents a breakdown voltage enhancement technique for power AlGaN/GaN HEMTs by using novel Air-bridge Field Plate (AFP). The device features a metal field plate that jumps from the source over the gate region and lands between gate and drain. Simulation results show that the HEMTs with Air-bridge Field Plate can provide a new degree of freedom to modulate the device surface electric field. In a device with gate to drain distance of 6 μm, gate length of 0.8 μm, two times higher forward blocking voltage of 450 V was obtained at V GS = -5 V when compared to a device with an optimized conventional field plate device (240 V) for a given process.

关键词： HEMTs MODFETs Gallium nitride Logic gates Aluminum gallium nitride Electric fields Silicon compounds

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Histogram-based image hashing for searching content-preserving copies

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2011年 6730 LNCS卷 83-108页

作者： Xiang, Shijun Kim, Hyoung Joong Department of Electronic Engineering School of Information Science and Technology Jinan University Guangzhou China State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing China CIST Graduate School of Information Management and Security Korea University Seoul Korea Republic of

ISBN: (纸本)9783642245558

Image hashing as a compact abstract can be used for content search. Towards this end, a desired image hashing function should be resistant to those content-preserving manipulations (including additive-noise like processing and geometric deformation operations). Most countermeasures proposed in the literature usually focus on the problem of additive noises and global affine transform operations, but few are resistant to recently reported random bending attacks (RBAs). In this paper, we address an efficient and effective image hashing algorithm by using the resistance of two statistical features (image histogram in shape and mean value) for those challenging geometric deformations. Since the features are extracted from Gaussian-filtered images, the hash is also robust to common additive noise-like operations (e.g., lossy compression, low-pass filtering). The hash uniqueness is satisfactory for different sources of images. With a large number of real-world images, we construct a hash-based image search system to show that the hash function can be used for searching content-preserving copies from the same source. © 2011 Springer-Verlag Berlin Heidelberg.

关键词： Additive noise

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Optimal data scheduling for P2P VoD streaming systems

Optimal data scheduling for P2P VoD streaming systems

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16th IEEE International Conference on Parallel and Distributed Systems, ICPADS 2010

作者： Yu, Qifeng Chen, Daoxu Department of Computer Science and Technology State Key Laboratory for Novel Software and Technology Nanjing University China

ISBN: (纸本)9780769543079

Media streaming services have been much more popular nowadays, and these services consume lots of network bandwidth. Peer-to-Peer(P2P) technology has been employed in the streaming systems to save the server bandwidth consumption and enhance the system scalability. In a P2P streaming system, the quality of the data scheduling scheme will largely affect the server stress that being saved. In this paper, we present our optimal data scheduling scheme to achieve both server stress minimization and fairness among users when the playback continuities of the users are guaranteed. The data scheduling scheme we proposed is based on the maximum network flow problem, and it is proved to be polynomial. Simulations also show that the time consumption for the computation of the optimal scheduling is acceptable, and the result of the scheduling also achieves small node degree bound which makes it practical. © 2010 IEEE.

关键词： Scheduling

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A binary graph reduction algorithm for multi-constrained QoS routing 10

A binary graph reduction algorithm for multi-constrained QoS...

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Proceedings of the Second Asia-Pacific Symposium on Internetware

作者： Zhang, Sheng Qian, Zhuzhong Lu, Sanglu Chen, Daoxu State Key Laboratory for Novel Software Technology Nanjing University China Department of Computer Science and Technology China

ISBN: (纸本)9781450306942

A lot of network services and applications are being designed to support quality-of-service (QoS) routing. One of the key problems is to find a feasible path that satisfies multiple QoS requirements, i.e., Multi-Constrained Path (MCP) problem which is known to be NP-complete. Many heuristic and approximation algorithms have been proposed to solve this problem. However, most of them converted it into the classic shortest path problem by transforming multiple QoS weights into single weight. In this paper, we propose a binary graph reduction (BGR) algorithm to convert network graph into a simplified graph by removing redundant edges before constructing a routing path. BGR improves system performance from two aspects: i) BGR decreases the decision-making time, which then decreases the delay of end users;ii) BGR removes some abnormal anti-heuristic redundant edges from network graph, so that the actual routing algorithm could get a better result. We use a multimedia delivery system to illustrate these advantages in this paper. Simulation results also approve the efficiency of the proposed BGR algorithm.

关键词： Quality of service

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