17466332
Nowhere-zero 3-flows in products of graphs
A graph G is an odd-circuit tree if every block of G is an odd length circuit. It is proved in this paper that the product of every pair of graphs G and H admits a nowhere-zero 3-flow unless G is an odd-circuit tree and H has a bridge. This theorem is a partial result to the Tutte’s 3-flow conjecture and generalizes a result by Imrich and Skrekovski [7] that the product of two bipartite graphs admits a nowhere-zero 3-flow. A byproduct of this theorem is that every bridgeless Cayley graph G 1⁄4 Cayð ;SÞ on an abelian group with a minimal generating set S admits a nowhere-zero 3-flow except for odd prisms. 2005 Wiley Periodicals, Inc. J Graph Theory 50: 79–89, 2005
11462933
On flows in bidirected graphs
Bouchet conjectured that every bidirected graph which admits a nowhere-zero bidirected flow will admit a nowhere-zero bidirected 6-flow [A. Bouchet, Nowhere-zero integer flows on a bidirected graph, J. Combin. Theory Ser. B 34 (1983) 279-292]. He proved that this conjecture is true with 6 replaced by 216. Zyka proved in his Ph.D dissertation that it is true with 6 replaced by 30. Khelladi proved it is true with 6 replaced with 18 for 4-connected graphs [A. Khelladi, Nowhere-zero integer chains and flows in bidirected graphs, J. Combin. Theory Ser. B 43 (1987) 95-115]. In this paper, we prove that Bouchet's conjecture is true for 6-edge connected bidirected graphs.
46565546
Arc-disjoint circuits in digraphs
36530209
Determination of the star valency of a graph
The star valency of a graph G is the minimum, over all star decompositions π, of the maximum number of elements in π incident with a vertex. The maximum average degree of G, denoted by dmax-ave(G), is the maximum average degree of all subgraphs of G. In this paper, we prove that the star valency of G is either ⌈dmax-ave(G)/2⌉ or ⌈dmax-ave(G)/2⌉ + 1, and provide a polynomial time algorithm for determining the star valency of a graph.
17086856
A note about shortest cycle covers
Let G be a graph with odd edge-connectivity r. It is proved in this paper that if r>3, then G has a 3-cycle (1,2)-cover of total length at most ((r+1)|E(G)|)/r.
13303898
Chords of longest circuits in 3-connected graphs
Thomassen conjectured that every longest circuit of a 3-connected graph has a chord. The conjecture is verified in this paper for projective planar graphs with minimum degree at least 4.
15885692
Localization in Wireless Sensor Grids
This work reports experiences on using radio ranging to position sensors in a grid topology. The implementation is simple, efficient, and could be practically distributed. The paper describes an implementation and experimental result based on RSSI distance estimation. Novel techniques such as fuzzy membership functions and table lookup are used to obtain more accurate result and simplify the computation. An 86% accuracy is achieved in the experiment in spite of inaccurate RSSI distance estimates with errors up to 60%.
2587849
Quantifying aspects in middleware platforms
Middleware technologies such as Web Services, CORBA and DCOM have been very successful in solving distributed computing problems for a large family of application domains. As middleware systems are getting widely adopted and more functionally mature, it is also increasingly difficult for the architecture of middleware to achieve a high level of adaptability and configurability, due to the limitations of traditional software decomposition methods. Aspect oriented programming has brought us new design perspectives because it permits the superimpositions of multiple abstraction models on top of one another. It is a very powerful technique in separating and simplifying design concerns. In this paper, we first show that, through the quantification of aspects in the legacy implementations, the modularity of middleware architecture is greatly hindered by the ubiquitous existence of tangled logic. We then go one step further by factoring out a number of aspects identified in the mining work and re-implementing them as aspect programs. The aspect oriented re-factorization allows us to apply a set of software engineering metrics to quantify the changes of the re-factored system in both the structural complexity and the runtime performance. The aspect oriented re-factoring proves that the aspect oriented programming is capable of composing orthogonal design requirements. The final "woven" system is able to correctly provide both the fundamental functionality and the "aspectized" functionality with negligible overhead and a leaner architecture. Further more, the configurability of middleware is dramatically increased because the "aspectized" features can be configured in and out during the compile-time
14923326
Co-histogram and Image Degradation Evaluation
The tool for image degradation evaluation addressed in this paper is called co-histogram, which is a statistic graph generated by counting the corresponding pixel pairs of two images. The graph is a two-dimensional joint probability distribution of the two images. A co-histogram shows how the pixels are distributed among combinations of two image pixel values. By means of co-histogram, we can have a visual understanding of PSNR, and the symmetry of a co-histogram is also significant for objective evaluation of image degradation. Our experiments with image degradation models of image compression, convolution blurring and geometric distortion perform the importance of the co-histogram.
40273501
Pattern Discovery in Probabilistic Databases
Modeling probabilistic data is one of important issues in databases due to the fact that data is often uncertainty in real-world applications. So, it is necessary to identify potentially useful patterns in probabilistic databases. Because probabilistic data in 1NF relations is redundant, previous mining techniques don't work well on probabilistic databases. For this reason, this paper proposes a new model for mining probabilistic databases. A partition is thus developed for preprocessing probabilistic data in a probabilistic databases. We evaluated the proposed technique, and the experimental results demonstrate that our approach is effective and efficient.
36704299
Error differentiation with measurements based on wave patterns
We investigate the efficiency and fairness potential of an error differentiation mechanism with measurements based on wave patterns. Our work is focused on a receiver-oriented protocol, TCP-Real that allows for measurement-based congestion detection and error recovery instead of a 'blind' increase/decrease window adjustment. We conduct a comparative evaluation of congestion control mechanisms of standard TCP, TCP-Real, and TCP-friendly protocols in multiplexed wired/wireless networks for both delay-tolerant and delay-sensitive applications. We show that the receiver-oriented communication of TCP-Real (i) diminishes the impact of reverse path asymmetry on the transmission rate, (ii) allows for error recovery tactics that are responsive to the nature of the error detected (i.e. congestion versus bit corruption), and (iii) dictates transmission rate adjustments that conform to the level of present contention. As a direct impact of this design, we realize the inherent properties of our protocol to produce comprehensive dynamics in heterogeneous environments, in contrast to the occasionally limited efficiency of standard TCP and the application-specific design of TCP-friendly protocols.