This paper examines the formation of self-organizing feature maps (SOFM) by the direct optimization of a cost function through a genetic algorithm (GA). The resulting SOFM is expected to produce simultaneously a topol...
详细信息
This paper examines the formation of self-organizing feature maps (SOFM) by the direct optimization of a cost function through a genetic algorithm (GA). The resulting SOFM is expected to produce simultaneously a topologically correct mapping between input and output spaces and a low quantization error. The proposed approach adopts a cost (fitness) function which is a weighted combination of indices that measure these two aspects of the map quality, specifically, the quantization error and the Pearson correlation coefficient between the corresponding distances in input and output spaces. The resulting maps are compared with those generated by the Kohonen's self-organizing map (SOM) algorithm in terms of the quantization error (QE), the weighted topological error (WTE) and the Pearson correlation coefficient (PCC) indices. The experiments show the proposed approach produces better values of the quality indices as well as is more robust to outliers.
The lattice cellular Potts model is widely used to represent physical and biological cellular systems. Standard implementations of this model in the literature employ inefficient Monte Carlo protocols to select elemen...
详细信息
The development of programs for parallel architectures focusing to achieve high indices of performance is a hard task. The programmer must deal with two classes of problems, one related to describing the application c...
详细信息
Most of the traffic in the Internet nowadays is transmitted using TCP, or transport control protocol. The stability of the Internet depends on the congestion control being performed by this protocol, as well as equiva...
详细信息
Most of the traffic in the Internet nowadays is transmitted using TCP, or transport control protocol. The stability of the Internet depends on the congestion control being performed by this protocol, as well as equivalent mechanisms employed by other protocols. The ECN technique (explicit congestion notification), in which packets forwarded by routers are marked whenever congestion is about to occur (or already occurring), allows a transmitter to reduce the sending rate accordingly without relying on packet drops. ECN has not been fully explored, particularly regarding multicast protocols. This paper presents models of poll-based reliable multicast protocols and extends them with a new single-rate congestion control mechanism that harnesses ECN. Simulation results show that it provides fairness between flows from multiple sources, and is TCP-friendly. Further, they demonstrate the substantial efficiency gain obtained with the use of ECN in multicast.
The development of programs for parallel architectures focusing to achieve high indices of performance is a hard task. The programmer must deal with two classes of problems, one related to describing the application c...
详细信息
The development of programs for parallel architectures focusing to achieve high indices of performance is a hard task. The programmer must deal with two classes of problems, one related to describing the application concurrency and data dependencies, and other related to exploiting efficiently the processing resources of the architecture, in order to obtain an efficient implementation for a specific hardware configuration. Since cluster technology allows building parallel computers are highly scalable - particularly in terms of number of nodes, processors and amount of memory - programming and execution levels must be considered independently to achieve performance portability. This paper presents Anahy, an environment for exploiting high performance computing on cluster architectures. It is highlighted the Anahy programming interface and some features of its implementation as well as a performance evaluation.
At 70 miles per hour, overcoming aerodynamic drag represents about 65% of the total energy expenditure for a typical heavy truck vehicle. The goal of this US Department of Energy supported consortium is to establish a...
详细信息
暂无评论