Real-Time odor classification through sequential bayesian filtering

The classification of volatiles substances with an e-nose is still a challenging problem, particularly when working under real-time, out-of-the-lab environmental conditions where the chaotic and highly dynamic characteristics of the gas transportation induce an almost permanent transient state in the e-nose readings. In this work, a sequential Bayesian filtering approach is proposed to efficiently integrate information from previous e-nose observations while updating the belief about the gas class on a real-time basis. We validate our proposal with two real olfaction datasets composed of dynamic time-series experiments (gas transitions are Considered, but no mixture of gases), showing an improvement in the classification rate when compared to a stand-alone probabilistic classifier.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Planar Odometry from a Radial Laser Scanner. A Range Flow-based Approach

In this paper we present a fast and precise method to estimate the planar motion of a lidar from consecutive range scans. For every scanned point we formulate the range flow constraint equation in terms of the sensor velocity, and minimize a robust function of the resulting geometric constraints to obtain the motion estimate. Conversely to traditional approaches, this method does not search for correspondences but performs dense scan alignment based on the scan gradients, in the fashion of dense 3D visual odometry. The minimization problem is solved in a coarse-to-fine scheme to cope with large displacements, and a smooth filter based on the covariance of the estimate is employed to handle uncertainty in unconstraint scenarios (e.g. corridors). Simulated and real experiments have been performed to compare our approach with two prominent scan matchers and with wheel odometry. Quantitative and qualitative results demonstrate the superior performance of our approach which, along with its very low computational cost (0.9 milliseconds on a single CPU core), makes it suitable for those robotic applications that require planar odometry. For this purpose, we also provide the code so that the robotics community can benefit from it.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Spanish Government under project DPI2014-55826-R and the grant program FPI-MICINN 2012

Bit error evaluation of optically preamplified direct detection receiver with Fabry-Perot optical filters

The error performance of a preamplified, direct detection receiver with an optical filter of the Lorentzian type is studied. The analysis takes into account the influence of the optical intersymbol interference (ISI). A closed-form expression of the moment generating function (MGF) of the decision variable is derived. Error probabilities are evaluated from the MGF using a saddlepoint approximation. The Gaussian approximation is also examined. The detection sensitivity in terms of a quantum limit is calculated. The results show that there exists an optimum optical bandwidth, the reason being a tradeoff between the effect of ISI and the spontaneous emission noise. It is also shown that the Gaussian approximation gives a good estimate of the error probability, allowing to find in a simple manner the optimum parameters of optically preamplified, direct detection receive

A novel approach to bioelectrical impedance plethysmography for the assessment of arterial and venous circulatory problems in the forearm

Peripheral vascular disease (PVD) and/or peripheral arterial disease (PAD) are sicknesses known to inadequate delivery of either arterial or venous blood towards the extremities. Such sickness may trigger complications owing to the lack of transport of oxygen and nutrients, thus causing hypoxic events that may eventually prompt to ischaemic tissue or even the loss of the compromised limb. One of the most prominent indicators of prosperous health is blood volume and flow. The basic information within these health parameters may show cardiovascular problems or the advance of further complications related to other diseases like diabetes. In clinical setting, there effective methods to measure these parameters like Doppler ultrasound, photoplethysmography or venous occlusion plethysmography. These methods take measurements from either single vessels and/or small volume of tissue. However, it is difficult to establish a relation between the obstruction of arterial and/or venous circulation and the amount of blood received by the tissue. Bioelectrical impedance plethysmography (iPG) measures blood changes by driving a small amount of AC current into the body and after measuring the potential created by fluids flowing through tissue. This technique apart from taking measures within defined volumes of tissue, it is easy to use as only needs four electrodes on the skin. Hence, a bespoken bioelectrical impedance device including hardware and software was built ready to measure changes in blood volume/flow in the upper limbs. The system was assessed in an in-vivo controlled environment with 8 participants. The blood flow towards their left arms was altered by constricting the upper arm with a cuff at three levels: 1) below venous pressure 2) amongst venous and arterial pressure and 3) during total occlusion. Simultaneously, measurements from various instruments like ECG, Doppler ultrasound, laser Doppler flowmetry and PPG were taken and compared to the measurements obtained from the iPG instrument and defining its correlation with the impedimetric signal. The results from the experiments showed that the bioelectrical impedance signal changed in basal and arterial pulses showing specific characteristics for each kind of occlusion. The data indicated that it is possible to differentiate between a venous and arterial occlusion by examining both components of the impedance signal. The impedance during venous occlusion dropped in average 0.658±0.230% from the baseline. On the other hand, during arterial occlusion the base impedance dropped in a higher rate approximately 1.13±04.82%, indicating a differentiator during both type of blood flow disruption. Furthermore, the impedance plethysmography waveform morphology also reshaped during these occlusive periods. The whole waveform during artificial venous obstruction increased in magnitude, the systolic peak rose 31.80%, the dicrotic notch 47.73% and the diastolic point 31.92%, where the value of the latter was higher than the dicrotic notch point. In contrast, in the time of partial arterial occlusion the waveform also increased in size at all these points, but its shape was altered. The impedance magnitude at the diastolic point went below the ones at the dicrotic notch. These fluctuations provided additional further information that it might be possible to differentiate amongst venous and arterial occlusions. By consolidating the data obtained by the iPG device, it is possible to produce an index ratio between the basal impedance and these three reference points which may help to identify early circulatory problems in the arterial and/or venous systems

NOTEWORTHY BIRD RECORDS IN SONTECOMAPAN, VERACRUZ, MEXICO

Registramos observaciones sobresalientes de aves en el sur del estado de Veracruz. Se reporta la tercera localidad donde se ha registrado la polluela pechigris (Laterallu sexilis) para el país, el primer registro para el estado del rascón cuello rufo (Aramides axillaris), el segundo registro de colimbo mayor (Gavia immer) para el sur del estado, así como el registro de una pareja de hocofaisanes (Crax rubra) en el área de manglar de Sontecomapan

Dynamic images to address conceptual nodes about mechanical waves: Example materials and preliminary results of the experimentation of the teacher training module IMAGONDE

In the framework of the 2002-03 project “Fisica per la Formazione Culturale - FORMazione Insegnanti” funded by Italy ministry of Education, a set of training materials, focused on mechanical waves, has been developed. The core of the materials is represented by animated images purposely designed in order to: 1) address intrinsically dynamic aspects of one-dimensional impulses/waves propagation on a string; 2) have the trainees reflect upon students’ difficulties in reading/interpreting static images (as the ones which are featured in common textbooks) and animations. In this paper we discuss example materials concerning transversal impulses on strings to address conceptual nodes such as: 1) configuration of the string at a given time and its abstract representation; 2) displacement vs. time graph of a string element and its abstract representation; 3) relationships between the two abstract representations; 4) modelization of mechanical wave propagation in one dimension. Moreover the results of the experimentation of the training materials in the framework of the Post Graduate School to Became Physics Teacher in Secondary Schools are presented and commented

Online Estimation of 2D Wind Maps for Olfactory Robots

This work introduces a novel solution to approximate in real time the 2D wind flow present in a geometrically known environment. It is grounded on the probabilistic framework provided by a Markov random field and enables the estimation of the most probable wind field from a set of noisy observations, for the case of incompressible and steady wind flow. Our method delivers reasonably precise results without falling into common unrealistic assumptions like homogeneous wind flow, absence of obstacles, etc., and performs very efficiently (less than 0.5 seconds for an environment represented with a 100x100 cell grid). This approach is then quite suitable for applications that require real-time estimation of the wind flow, as for example, the localization of gas sources, prediction of the gas dispersion, or the mapping of the gas distribution of different chemicals released in a given scenario.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech