Evaluating the Effectiveness of Ensembles of Decision Trees in Disambiguating Senseval Lexical Samples

This paper presents an evaluation of an ensemble--based system that participated in the English and Spanish lexical sample tasks of Senseval-2. The system combines decision trees of unigrams, bigrams, and co--occurrences into a single classifier. The analysis is extended to include the Senseval-1 data.Comment: Appears in the Proceedings of the ACL-02 Workshop on Word Sense Disambiguation: Recent Successes and Future Directions, July 11, 2002, Philadelphia, P

Stochastic Multipath Model for the In-Room Radio Channel based on Room Electromagnetics

We propose a stochastic multipath model for the received signal for the case where the transmitter and receiver, both with directive antennas, are situated in the same rectangular room. This scenario is known to produce channel impulse responses with a gradual specular-to-diffused transition in delay. Mirror source theory predicts the arrival rate to be quadratic in delay, inversely proportional to room volume and proportional to the product of the antenna beam coverage fractions. We approximate the mirror source positions by a homogeneous spatial Poisson point process and their gain as complex random variables with the same second moment. The multipath delays in the resulting model form an inhomogeneous Poisson point process which enables derivation of the characteristic functional, power/kurtosis delay spectra, and the distribution of order statistics of the arrival delays in closed form. We find that the proposed model matches the mirror source model well in terms of power delay spectrum, kurtosis delay spectrum, order statistics, and prediction of mean delay and rms delay spread. The constant rate model, assumed in e.g. the Saleh-Valenzuela model, is unable to reproduce the same effects.Comment: 14 pages, Manuscript Submitted to IEEE Transaction on Antennas and Propagatio

Sustainable production systems for organic apple production

Organic apples are often sold for fresh consumption and therefore have to obtain high quality requirements. The fruits must obtain the right size and be undamaged without important infections of pest and diseases. Apple scab causes brown or black spots on the fruits and severe infections can result in fruits not suitable for consumption. This disease causes big reduction in yield and quality in organic production. Copper is an effective fungicide to control diseases and is used in organic apple production in some European countries. Copper has not been permitted in Denmark the last 10 years and the European Union wants to reject it from the list of pesticides permitted in organic production. To improve the quality and yield in organic apple production, it is important to find the best culture techniques. Combinations of cultivars, nitrogen availability, rootstocks and planting distances are tried to prevent or reduce apple scab infections