Abstract
Recent developed button heat pulse probes (BHPP) demonstrated a great potential for soil water content measurements. This new probe compared to conventional heat pulse probes (HPP), does not use needles, and measurement accuracy is significantly improved. This new design, with the possibility to assembly the probe and electronics in the same package, with low-cost, and with less power consumption compared to conventional HPP, make it suitable to be connected to wireless data acquisition systems in precision agriculture. The probe was tested in agar to demonstrate the potential advantages of the button heat pulse sensor for soil water content measurements. It was possible to have an 0.5 °C temperature rise with only 156mW of power consumption, a ten times power reduction in heat-pulse soil water content measurements. These tests showed the potential use of the button heat pulse sensor for the determination of soil water content. © 2010 IEEE.

Abstract
This article describes the concept, design, fabrication and experimental results of a touchscreen based on acoustic pulse recognition. It uses piezoelectric transducers fabricated from the piezoelectric polymer poly(vinylidene fluoride), PVDF, in its beta phase. The transducers are located at the edges of the panel in order to receive the acoustic pulses generated by the touches. Each transducer is connected to a readout electronic circuit composed by a differential charge amplifier and a comparator, whose output signal is attached to a microcontroller. The microcontroller uses an algorithm to determine the location of the touch, based on the time differences of the transducer signals. The touchscreen itself is made of ordinary glass, providing good durability and optical transparency. The experimental results obtained with the first prototype demonstrate the effectiveness of the method.

Abstract
The problem of predicting the next request during a user's navigation session has been extensively studied. In this context, higher-order Markov models have been widely used to model navigation sessions and to predict the next navigation step, while prediction accuracy has been mainly evaluated with the hit and miss score. We claim that this score, although useful, is not sufficient for evaluating next link prediction models with the aim of finding a sufficient order of the model, the size of a recommendation set, and assessing the impact of unexpected events on the prediction accuracy. Herein, we make use of a variable length Markov model to compare the usefulness of three alternatives to the hit and miss score: the Mean Absolute Error, the Ignorance Score, and the Brier score. We present an extensive evaluation of the methods on real data sets and a comprehensive comparison of the scoring methods.

Abstract
In this paper we present a software tool to be used in residential/household generic power circuitry analysis and simulation, under non-linear loads. This tool can both be used by electrical engineers and by students of electrical engineering. It has an easy-to-use, friendly interface, and can be used to teach design techniques or as a laboratory tool to study the applicability of known methods to real world practical situations. Also, the users may supply their own data. The simulated results are very close to the measured ones.

Abstract
Despite huge advances in wireless communications in the last few years, underwater wireless communications is still a not fully developed technology, due to the lack of efficiency of radio waves for underwater communication. This problem can be overcome by using acoustic waves instead. In order to implement high-speed acoustic communications, it is imperative to develop transducers with high performance at high frequency. In this paper, a study of both piezoelectric ceramics and polymers used as water-coupled ultrasonic transducers is presented. As the main goal is to analyze their performance for high-speed communications, the behaviour of the piezoelectric ceramic (lead zirconate titanate, PZT) and the piezoelectric polymer (poly(vynilidene fluoride), PVDF) at high frequencies in underwater environment are compared. Results show that PVDF has a better response under the same ideal conditions, mainly with increasing frequency. (C) 2010 Published by Elsevier Ltd.

Abstract