Abstract: This paper is a review of the techniques commonly used for pre-processing and processing of information obtained with different types of sensors. It also analyzes sensor modeling techniques, which are important when one wants to characterize the sensor responses and even get virtual sensors or estimators. This paper makes special emphasis on gas sensors MOS type, which are used particularly in electronic nose system, reason that in the article makes an overview of the problems most commonly reported in the olfactory systems electronic and applications related shall refer to this theme. In the last section provides some conclusions on the revision and will be discussed the possible work on the issues exposed.

Keywords: Modeling sensors, gas sensors, electronic nose systems, virtual sensors.

Abstract: The purpose of this paper is to present a review of techniques have been used to counteract the drift in chemical sensors commonly used in electronic nose systems. The drifts are changes in sensor response due to many factors and it is necessary to minimize their effects, one choice is controlling all parameters of the measure or applying processes and calibration algorithms to counteract the excesses that can not be controlled. This problem has been attacked from different approaches, the first of which corresponds to the correction of drift from the design and construction of new sensors, the second corresponds to the correction of the drifts in the classification stage, designing and implementing powerful classifiers improve the accuracy in the response and the discriminating power of electronic nose systems, the third approach addresses the problem from the space of representation of the feature set of the volatiles sensed, that is enhancing the response of the sensors in the characterization stage to perform the tasks of classifying and pattern recognition. This article presents a review of the most relevant works developed to mitigate this problem frequently presented in electronic nose systems with arrays of chemical sensors. Each approach has advantages and disadvantages for removing the drift, it will focus on techniques that address the problem from the preprocessed signal response of the sensor array, such as independent component analysis (ICA), principal component analysis (PCA), common principal component analysis (CPCA), between other techniques. This will allow us to conclude which is the best way to tackle the problem of drift and contribute to future work in this area.

Keywords: drift counteraction, Electronic Nose, gas-sensor

Abstract: CdSe quantum dot semiconductor optical amplifier is studied theoretically where the linear Absorption and emission coefficients, noise figure and small-signal gain are studied. a low noise figure is specified from these calculations.

Keywords: linear Absorption coefficient, linear emission coefficient, Rate equations (REs), noise figure.

Abstract: Chemically sensitive coatings according to supra-molecular chemistry are preferably combined with mass-sensitive devices. Thus, the quartz-crystal-balance (QCM) and the surface acoustic wave (SAW) oscillator allow to monitor inclusion phenomena from nano-gram down to the sub-femto-gram range. A deeper insight into the inclusion process of analytes by e.g. cyclodextrins, calixarenes and paracyclophanes was gained by modelling procedures which made the prediction of sensitivity and selectivity possible. The robustness of the coatings is enhanced by cross-linking which leads to functionalized polymers. This strategy is further developed by imprinting, in most cases the template is identical to the analyte. Both gas- and liquid-phase measurements can be performed. The detection of aromatic, halogenated and polycyclic hydrocarbons is possible. Even complex mixtures are accessible to monitor e.g. oil degradation, composting and also process control procedures.

Abstract: Generally, the detection of particular DNA sequence is carried out by gel electrophoresis of DNA fragments amplified by polymerase chain reaction (PCR) using primers which are specific complementary sequence with the chosen region of DNA. Although, gel electrophoresis is simple and effective for detection of PCR products, ethidium bromide which is a common stain is a carcinogen. This approach lays the groundwork for incorporating the method into an integrated system for rapid PCR-based DNA analysis. Quartz crystal microbalance (QCM) biosensor is an extremely sensitive mass sensor, capable of measuring nanogram levels of mass changes. This is a great potential market for simple, cheap, rapid, and quantitative detection of specific genes. QCM require any non-labeling such as radio isotope, enzyme, and fluorescence tag. Therefore, the QCM appears to be a suitable and simple device for direct detection and label free monitoring of complementary olignucleotide hybridization for detection of application in many fields of work such as clinical diagnosis, epidemiology study, and bioterrorist weapon survey.

Keywords: Biosensors, Quartz crystal microbalance; DNA; Immobilization; Hybridization.

Abstract: This paper describes the emerging technology of computer aided leaf digital image analysis. It is based on a fast, non-destructive measurement technique of leaf chlorophyll content imaging based on measurements of leaf reflectance. The validity of the method is demonstrated by direct comparison of conventional extraction of both leaf chlorophyll pigments from the same species with chlorophyll estimates based on leaf reflectance imagery.
The leaves of the species selected for this paper are characterized by heterogeneous chlorophyll distributions. The application of software developed for image analysis at the spatial level (2D) of physiological processes or state variables does allow revealing the morphological 31 structures at the origin of the spatial variation of leaf chlorophyll.

Keywords: Physical modelling, leaf chlorophyll imaging, spatial analysis, RGB camera.