Poor air quality is a major public health concern in both developed and developing countries. Continued exposure to environments with high pollutant content is estimated to cause nearly 2.5 million premature deaths per year all over the world, including 370,000 in Europe. The worldwide concern about pollution is reflected in the development and implementation of increasingly stringent policies to limit the wide range of contaminants that contribute to poor air quality. However, the sensing of these contaminants in a comprehensive, reliable, and low-cost manner still remains a major challenge. Electronic noses are intelligent systems that can classify and quantify different gases and odors. In this article, the authors evaluate which classification approaches are most effective for identifying and distinguishing between environmental pollutants, and they describe a novel Web-based software framework that incorporates these classifiers to detect pollutants.

Insufficient control of tomato ripening before harvesting and infection by fungal pests produce large economic losses in world tomato production. Aroma is an indicative parameter of the state of maturity and quality of the tomato. This study aimed to design an electronic system (TOMATO-NOSE) consisting of an array of 12 electrochemical sensors, commercial metal oxide semiconductor sensors, an optical camera for a lateral flow reader, and a smartphone application for device control and data storage. The system was used with tomatoes in different states of ripeness and health, as well as tomatoes infected with Botrytis cinerea. The results obtained through principal component analysis of the olfactory pattern of tomatoes and the reader images show that TOMATO-NOSE is a good tool for the farmer to control tomato ripeness before harvesting and for the early detection of Botrytis cinerea.

This work presents the performance analysis of an Ultrasonic Local Positioning System (ULPS). The system is composed of four beacons, forming a square structure in the ceiling of a rectangular room, that emit orthogonal Kasami codes BPSK modulated with a carrier frequency of 50 kHz. These emissions are detected by the receiver by pulse compression, giving the system high precision and robustness to noise. A complete model of the system has been built to conduct this study, considering effects such as the ultrasonic transducers response, signal attenuation in air, multipath propagation, reflection coefficient of walls and floor and receiver response. This model helps to identify critical zones where the self-induced noise generated in the cross-correlations masks the main peaks of the auto-correlations, making it difficult to obtain reliable Time-of-Flights from which the receiver's position is determined. Also, the dependence of these critical zones with different parameters integrated in the model is investigated.

The liquid bridge can be used either as an accelerometer for steady accelerations or as a tensiometer. This can be done by fitting the theoretical predictions to the observed contours. The procedure involves two calculations. First, the contour has to be recognized in a liquid bridge image. The result is either a curve or a set of points which represent the contour. Second, the values of the parameters characterizing the contour have to be inferred by fitting the theoretical predictions. In this contribution, a method to perform this double calculation is presented. The method is used to measure both the volume of the liquid bridge and the Bond number in several experiments. The results are compared with those obtained from a procedure established previously. Finally, the relative advantages of the two methods are discussed.

Ultrasonic positioning systems presents performance problems when the object to be localized is in movement. The reasons are the degradation suffered by emitted sequences because of Doppler shifts, and the low level of orthogonality of the set of codes when they are being identified in different beacons. In this work, a search of a set of four 256-element polyphase sequences has been carried out, in order to improve the resilience to velocity possessed by other well-known codes, maintaining good orthogonality properties. As result, the obtained set can be used in an ultrasonic Local Positioning System (LPS), where the codes can be detected up to 1.5 m/s.

This study addresses the development of a miniaturized wireless sensing module (electronic nose) for a personal use in air quality detection.