3480516
Integrative negotiation in complex organizational agent systems
This paper addresses the problem of negotiation in a complex organizational context and tries to bridge the gap between self-interested negotiation and cooperative negotiation. An integrative negotiation mechanism is introduced, which enables agents to choose any attitude from the extremes of self-interested and cooperative to those that are partially self-interested and partially cooperative. This mechanism is based on and also extends the motivational qualities(MQ) framework for evaluating which task an agent should pursue at each time point. Experimental work verifies this mechanism and explores the question whether it always improves the social welfare to have an agent be completely cooperative.
47233627
Integrative negotiation in complex organizational agent systems
This paper introduces an integrative negotiation mechanism, which enables agents to choose any attitude from the extremes of self-interested and fully cooperative to those that are partially self-interested and partially cooperative. Experimental work verifies this mechanism and explores the question whether it always improves the social welfare to have an agent be completely cooperative. It is found that it is good for the organization to have agents being partially cooperative in their local negotiation with other agents rather than being fully cooperative, in order to deal more effectively with the uncertainty of not having a more informed view of the state of the entire agent organization.
35432211
Constrained Total Variation Minimization and Application in Computerized Tomography
We present a simple framework for solving different ill-posed inverse problems in image processing by means of constrained total variation minimizations. We argue that drawbacks commonly attributed to total variation algorithms (slowness and incomplete fit to the image model) can be easily bypassed by performing only a few number of iterations in our optimization process. We illustrate this approach in the context of computerized tomography, that comes down to inverse a Radon transform obtained by illuminating an object by straight and parallel beams of x-rays. This problem is ill-posed because only a finite number of line integrals can be measured, resulting in an incomplete coverage of the frequency plane and requiring, for a direct Fourier reconstruction, frequencies interpolation from a polar to a Cartesian grid. We introduce a new method of interpolation based on a total variation minimization constrained by the knowledge of frequency coefficients in the polar grid, subject to a Lipschitz regularity assumption. The experiments show that our algorithm is able to avoid Gibbs and noise oscillations associated to the direct Fourier method, and that it outperforms classical reconstruction methods such as filtered backprojection and Rudin-Osher-Fatemi total variation restoration, in terms of both PSNR and visual quality.
1561680
Design of full band IIR digital differentiators
This paper presents an efficient method for designing full band IIR digital differentiators in the complex Chebyshev sense. The proposed method is based on the formulation of a generalized eigenvalue problem by using the Remez multiple exchange algorithm. Therefore, a set of filter coefficients can be easily obtained by solving the eigenvalue problem to find the absolute minimum eigenvalue, and then the complex Chebyshev approximation is attained through a few iterations starting from a given initial guess. The proposed algorithm is computationally efficient because it not only retains the speed inherent in the Remez exchange algorithm, but also simplifies the interpolation step. One design example is presented and compared with the conventional methods. It can be seen that the design results obtained by using the proposed method are better than that in the conventional methods.
10589983
Group membership and wide-area master-worker computations
Group communications systems have been designed to provide an infrastructure for fault-tolerance in distributed systems, including wide-area systems. In our work on master-worker computation for GriPhyN, which is a large project in the area of the computational grid, we asked the question should we build our wide-area master-worker computation using wide-area group communications? This paper explains why we decided doing so was not a good idea.
5639888
Strategies for using additional resources in parallel hash-based join algorithms
Hash-based join is a compute- and memory-intensive algorithm. It achieves good performance and scales well to large datasets, if sufficient memory is available to hold the hash table and the distribution of computing had across nodes is balanced. We compare three adaptive algorithms that start with a partitioning of the hash table across a group of nodes and expand during the hash table building phase to additional resources, when memory on a node is used up. The split-based algorithm partitions the hash table range assigned to the node, on which memory is full, into two segments and assigns one of the segments to a new node in the system. The replication-based algorithm replicates the hash table range on a new node. The hybrid algorithm combines the first and second strategies in order to address each strategy's short comings. We perform an experimental performance evaluation of these algorithms on a PC cluster. Our results show that among the three algorithms, in most cases the hybrid algorithm either performs close to the better of the two or is the best algorithm.
26388893
Grouping edge points into line segments by sequential Hough transformation
An algorithm to group edge points into digital line segments with Hough transformation is described. The edge points are mapped onto the parameter domain discretized at specific intervals, on which peaks appear to represent different line segments. By modeling each peak as a Gaussian function in the parameter domain, a region to which the edge points are supposed to be mapped is determined. Then the edge points are grouped and the parameters for a line segment are computed. For the edges including multiple line segments, a sequential Hough transformation for detecting peaks one by one in the parameter domain is implemented, and the points from the region around each peak are grouped, thus the line segments are described. Experiments show the robustness of the algorithm implemented on both the generated edges disturbed by different noise levels and real images taken from an indoor environment.