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Full-Text Articles in Physical Sciences and Mathematics

Angular Mobility Assisted Coverage In Directional Sensor Networks, Cyriac Kandoth, Sriram Chellappan Dec 2009

Angular Mobility Assisted Coverage In Directional Sensor Networks, Cyriac Kandoth, Sriram Chellappan

Computer Science Faculty Research & Creative Works

In this paper, we consider the issue of angular mobility assisted coverage enhancement in directional camera sensor networks. in our model, each sensor can visually capture (i.e. sense) events within a sector in its field of view and can also rotate about a fixed axis to enhance its coverage. the problem we particularly address is how to enhance blanket coverage leveraging angular mobility of the sensors in the network starting from an arbitrary initial deployment. the core idea of our algorithm, called the Face Away algorithm, is to use the known directions of neighboring sensors to find the direction with …


Digital Logic Based Encoding Strategies For Steganography On Voice-Over-Ip, Hui Tian, Ke Zhou, Hong Jiang, Dan Feng Oct 2009

Digital Logic Based Encoding Strategies For Steganography On Voice-Over-Ip, Hui Tian, Ke Zhou, Hong Jiang, Dan Feng

CSE Conference and Workshop Papers

This paper presents three encoding strategies based on digital logic for steganography on Voice over IP (VoIP), which aim to enhance the embedding transparency. Differing from previous approaches, our strategies reduce the embedding distortion by improving the similarity between the cover and the covert message using digital logical transformations, instead of reducing the amount of the substitution bits. Therefore, by contrast, our strategies will improve the embedding transparency without sacrificing the embedding capacity. Of these three strategies, the first one adopts logical operations, the second one employs circular shifting operations, and the third one combines the operations of the first …


Optimal-Location-Selection Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li Aug 2009

Optimal-Location-Selection Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li

Research Collection School Of Computing and Information Systems

This paper introduces and solves a novel type of spatial queries, namely, Optimal-Location-Selection (OLS) search, which has many applications in real life. Given a data object set D_A, a target object set D_B, a spatial region R, and a critical distance d_c in a multidimensional space, an OLS query retrieves those target objects in D_B that are outside R but have maximal optimality. Here, the optimality of a target object b \in D_B located outside R is defined as the number of the data objects from D_A that are inside R and meanwhile have their distances to b not exceeding …


On Efficient Mutual Nearest Neighbor Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li Aug 2009

On Efficient Mutual Nearest Neighbor Query Processing In Spatial Databases, Yunjun Gao, Baihua Zheng, Gencai Chen, Qing Li

Research Collection School Of Computing and Information Systems

This paper studies a new form of nearest neighbor queries in spatial databases, namely, mutual nearest neighbour (MNN) search. Given a set D of objects and a query object q, an MNN query returns from D, the set of objects that are among the k1 (≥ 1) nearest neighbors (NNs) of q; meanwhile, have q as one of their k2(≥ 1) NNs. Although MNN queries are useful in many applications involving decision making, data mining, and pattern recognition, it cannot be efficiently handled by existing spatial query processing approaches. In this paper, we present …


Generating Derivative Structures From Multilattices: Algorithm And Application To Hcp Alloys, Gus L. W. Hart, Rodney W. Forcade Jul 2009

Generating Derivative Structures From Multilattices: Algorithm And Application To Hcp Alloys, Gus L. W. Hart, Rodney W. Forcade

Faculty Publications

We present an algorithm for generating all derivative superstructures of a nonprimitive parent lattice. The algorithm has immediate application in important materials design problems such as modeling hexagonal-close-packed (hcp) alloys. Extending the work of Hart and Forcade [Phys. Rev. B 77, 224115 (2008)] (which applies only to Bravais lattices), this approach applies to arbitrary multilattices. The algorithm enumerates superlattices and atomic configurations using permutation groups rather than direct geometric comparisons. The key concept is to use the quotient group associated with each superlattice to determine all unique atomic configurations. The algorithm is very efficient; the run time scales linearly with …


Computing Prime Harmonic Sums, Eric Bach, Dominic Klyve, Jonathan P. Sorenson Jan 2009

Computing Prime Harmonic Sums, Eric Bach, Dominic Klyve, Jonathan P. Sorenson

Scholarship and Professional Work - LAS

We discuss a method for computing Σ �≤� 1/�, using time about �2/3 and space about �1/3. It is based on the Meissel-Lehmer algorithm for computing the prime-counting function �(�), which was adapted and improved by Lagarias, Miller, and Odlyzko. We used this algorithm to determine the first point at which the prime harmonic sum first crosses.