Assessment of the final metrological characteristics of a MOEMS-based NDIR spectrometer through system modeling and data processing

A model of a miniaturized non-dispersive infrared (NDIR) gas analysis system, aiming to predict the final system specifications, is presented. It comprises the different elements of the NDIR detector, including a surface micromachined Fabry-Perot tunable filter. These models have been used to estimate the response of the NDIR system to different gas mixtures. Multivariate regression methods like partial least squares allow recovering the true sample composition from the IR absorption spectra measured with the NDIR system, despite the limited selectivity of the filter. Combining model and data processing permits to predict the effect on the final system specification of design parameters. Here, we compare the effect of the technology used for the filter on the system errors.     

Infants of diabetic mothers (IDM). II -- Fibronectin and perinatal morbidity

OBJECTIVE: The objective of this study was to determine fibronectin levels in umbilical cord blood of infants of diabetic mothers (IDM) and evaluate a possible correlation with perinatal pathology. PATIENTS AND METHODS: A prospective study of 58 IDM (33 males and 25 females) and 58 control newborns (NB) (33 males and 25 females) was carried out. RESULTS: There were no differences in fibronectin levels between the two groups nor between the sexes. Perinatal morbidity was higher in the IDM group, but there was no correlation between fibronectin levels and the presence of perinatal pathology. CONCLUSIONS: Fibronectin levels are not useful in the perinatal evaluation of infants of diabetic mothers.     

Silphinene Sesquiterpenes as Model Insect Antifeedants

Silphinene sesquiterpenes are established chrysomelid antifeedants. In this work, nine silphinene analogs, 11-acetoxy-5-angeloyloxysilphinen-3-one (1), 11-acetoxy-5-tigloyloxysilphinen-3-one (2), 11-acetoxy-5-iso- butyryloxysilphinen-3-one (3), 11-hydroxy-5-angeloyloxysilphinen-3-one (4), 11,5-dihydroxysilphinen-3-one (5), 11,5-diacetoxysilphinen-3-one (6), 5,11-diisobutyryloxysilphinen-3-one (7), silphinen-3,5,11-trione (8), and O-methyl-5-epicantabrenolic acid methyl ester (10), and a presilphiperfolane sesquiterpene (9) were tested against several divergent insect species, including the lepidopteran Spodoptera littoralis, the chrysomelid Leptinotarsa decemlineata, and five aphid species, and their antifeedant effects were compared with those of picrotoxinin, a GABA-antagonist, and thymol, an allosteric modulator for insect GABA receptors. All insects tested responded to at least one silphinene analog and/or GABA antagonist. Compound 3 and thymol were effective antifeedants against all species tested except S. littoralis, with varying potencies according to their feeding ecologies. The toxicity of these compounds was species-dependent and did not correlate with their antifeedant effect.     

Study of the Catalytic Ozonation of Humic Substances in Water and Their Ozonation Byproducts

It is shown that using transition metals, especially Mn(II) and Ag(I), during ozonation of humic substances in water allows important reductions in the content of organic matter. Characterization of the organic compounds resulting from ozonation was made by concentrating the sample through liquid-liquid extraction or derivation with PFBOA.HCl, along with the GC/MS and GC/ECD techniques. In total, 110 different organic compounds were identified using GC/MS; mainly carboxylic acids, aromatics, hydrocarbons, aldehydes, ketones, and furan-carboxylic acids. The percentages of elimination or formation levels reached during ozonation are discussed.     

Optimal Trajectory Planning for Wheeled Mobile Robots Based on Kinematics Singularity

This research introduces a new optimality criterion for motion planning of wheeled mobile robots based on a cost index that assesses the nearness to singularity of forward and inverse kinematic models. Slip motions, infinite estimation error and impossible control actions are avoided escaping from singularities. In addition, high amplification of wheel velocity errors and high wheel velocity values are also avoided by moving far from the singularity. The proposed cost index can be used directly to complement path-planning and motion-planning techniques (e.g. tree graphs, roadmaps, etc.) in order to select the optimal collision-free path or trajectory among several possible solutions. To illustrate the applications of the proposed approach, an industrial forklift, equivalent to a tricycle-like mobile robot, is considered in a simulated environment. In particular, several results are validated for the proposed optimality criterion, which are extensively compared to those obtained with other classical optimality criteria, such as shortest-path, time-optimal and minimum-energy.     

A new control scheme for visual servoing

This research presents a new control scheme for visual servoing that takes into account the delay introduced by image acquisition and image processing. Firstly, previous control schemes for visual servoing are discussed and then a new control scheme is proposed and fully described. Afterwards, the capabilities (steady-state errors, stability margins, step time response, etc.) of the proposed control scheme and of previous ones are analytically analyzed and compared. Next, several simulations and experimental results are provided to validate the analytical results and to illustrate the benefits of the proposed control scheme. In particular, it is shown that this new control scheme clearly improves the performance of the previous ones.     

Water network cost optimization in a paper mill based on a new library of mathematical models

The increasing costs associated with water supply and the disposal of wastewater has stimulated industries to seek more efficient water management systems. Mathematical modelling and simulation can be a very valuable tool for the study of the multiple alternatives available whilst assessing optimum solutions for water management in industry. This study introduces a new steady state model library able to reproduce industrial water circuits. It has been implemented in a novel software framework for the representation, simulation and optimization of industrial water networks. A water circuit representing a paper mill has been modelled and simulated showing the capability to reproduce real case studies. Alternative scenarios for the water network have also been tested to assess the capability of the models to optimize water circuits minimizing total cost.     

A glass/silicon technology for low-power robust gas sensors

Semiconductor gas sensors are devices based on metallic oxides that operate at high temperatures for achieving good sensitivities to the gases of interest. Silicon micromachined structures are often used as platforms for obtaining both high temperatures and low-power consumption at the same time. In this paper, a microstructure based on the combination of micromachined silicon substrates and glass wafers is presented. The device incorporates an array of four different thin-film gas sensors that, depending on the design, can operate at the same or at different temperatures. The designs have been optimized by the finite element method (FEM) and the geometrical parameters of the structure have been selected in order to reduce the power consumption. The full process fabrication is presented. It is based on the combination of bulk micromachining, glass structuring, anodic bonding, and sensitive material deposition. Electrical, thermal, and mechanical tests have been done to demonstrate that the devices show high robustness and can reach high temperatures with low-power consumption.