Population based Ant Colony Optmization on FPGA

We propose to modify a type of ant algorithm called Population based Ant Colony Optimization (P-ACO) to allow implementation on an FPGA architecture. Ant algorithms are adapted from the natural behavior of ants and used to find good solutions to combinatorial optimization problems. General layout on the FPGA and algorithmic description are covered. The most notable achievements featured in this paper are a runtime reduction and including the approximation of the heuristic function by a small set of favored decisions which changes over time

Edge and bulk effects in the Terahertz-photoconductivity of an antidot superlattice

We investigate the Terahertz(THz)-response of a square antidot superlattice by means of photoconductivity measurements using a Fourier-transform-spectrometer. We detect, spectrally resolved, the cyclotron resonance and the fundamental magnetoplasmon mode of the periodic superlattice. In the dissipative transport regime both resonances are observed in the photoresponse. In the adiabatic transport regime, at integer filling factor $\nu =2$, only the cyclotron resonance is observed. From this we infer that different mechanisms contribute to converting the absorption of THz-radiation into photoconductivity in the cyclotron and in the magnetoplasmon resonances, respectively.Comment: 15 pages, 4 figures, submitted to Phys. Rev.

Partial task compaction reduces queuing delays in partitionable-array machines

Partitionable-array machines have emerged aspopular target architectures for e orts to devise effective on-line processor allocation strategies. As the available processors become fragmented, contiguous processor allocation schemes can fail to allocate a task despite there being sufficient processors in total to service the request. Tasks consequently wait longer to be serviced, and the system response degrades. In this paper, we report on the use of partial task compaction to improve the performance of contiguous processor allocation methods for partitionable linear arrays. A quadratic sequential time algorithm to schedule the ordered compaction of tasks on a reconfigurable bus system is presented. The length of the schedule is shown to be within twice that of the minimum schedule length. Experimental results indicate that the algorithm almost eliminates the problem of fragmentation, and reduces the system response time by significantly reducing allocation delays