333,153 research outputs found
Sometimes the Internet reads the question wrong: childrenâs search strategies & difficulties
When children search for information on a given topic, how do they go about searching for and retrieving information? What can their information seeking strategies tell us about the development of search interfaces for children's digital libraries, search engines and information repositories? We interviewed New Zealand (NZ) school children to seek insights into how they are conducting information searches during their education
Searching for partial Hadamard matrices
Three algorithms looking for pretty large partial Hadamard ma-
trices are described. Here âlargeâ means that hopefully about a third of a
Hadamard matrix (which is the best asymptotic result known so far, [8]) is
achieved. The first one performs some kind of local exhaustive search, and
consequently is expensive from the time consuming point of view. The second
one comes from the adaptation of the best genetic algorithm known so far
searching for cliques in a graph, due to Singh and Gupta [21]. The last one
consists in another heuristic search, which prioritizes the required processing
time better than the final size of the partial Hadamard matrix to be obtained. In
all cases, the key idea is characterizing the adjacency properties of vertices in a
particular subgraph Gt of Itoâs Hadamard Graph (4t) [18], since cliques of
order m in Gt can be seen as (m + 3) Ă 4t partial Hadamard matrices.Ministerio de Ciencia e InnovaciĂłn MTM2008-06578Junta de AndalucĂa FQM-016Junta de AndalucĂa P07-FQM-0298
Optimization of graded multilayer designs for astronomical x-ray telescopes
We developed a systematic method for optimizing the design of depth-graded multilayers for astronomical hard-x-ray and soft-Îł-ray telescopes based on the instrumentâs bandpass and the field of view. We apply these methods to the design of the conical-approximation Wolter I optics employed by the balloon-borne High Energy Focusing Telescope, using W/Si as the multilayer materials. In addition, we present optimized performance calculations of mirrors, using other material pairs that are capable of extending performance to photon energies above the W K-absorption edge (69.5 keV), including Pt/C, Ni/C, Cu/Si, and Mo/Si
A Multi-variate Discrimination Technique Based on Range-Searching
We present a fast and transparent multi-variate event classification
technique, called PDE-RS, which is based on sampling the signal and background
densities in a multi-dimensional phase space using range-searching. The
employed algorithm is presented in detail and its behaviour is studied with
simple toy examples representing basic patterns of problems often encountered
in High Energy Physics data analyses. In addition an example relevant for the
search for instanton-induced processes in deep-inelastic scattering at HERA is
discussed. For all studied examples, the new presented method performs as good
as artificial Neural Networks and has furthermore the advantage to need less
computation time. This allows to carefully select the best combination of
observables which optimally separate the signal and background and for which
the simulations describe the data best. Moreover, the systematic and
statistical uncertainties can be easily evaluated. The method is therefore a
powerful tool to find a small number of signal events in the large data samples
expected at future particle colliders.Comment: Submitted to NIM, 18 pages, 8 figure
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