By means of subsequent additive gold evaporations each electrode has shown a different thickness, resulting in distinct oscillation frequencies, always lower than that of the blank quartz. The geometry of each electrode has been tuned in order to keep most of the vibrational energy near to the region of the electrodes (energy trapping) and their area has been taken below the Bechmann’s number, so that the responses of the anharmonic overtones are negligible [14]. With this particular design and optimizing the distance between the electrodes [15], it is possible to maintain the channel-to-channel interference at a very low level.The implemented MQCM (Figure 1) is a four-ports network, characterized by a scattering matrix, representing the reflected and transmitted powers at each port, in the frequency domain.

In this way, the network is fully characterized by knowing the 10 independent coefficients, Sij.Figure 1.The prototype of a MQCM layed on a single quartz plate used for the electrical characterization.The outline of the scattering matrix measurements is depicted in Figure 2. The Sij parameters have been measured by a network analyzer (Agilent Technologies E5061A), exciting the jth port with a driving power in the frequency range of interest and reading the reflected power on the ith port. Contemporarily, the remaining two ports have been closed with the internal adapting impedance of the instrument, i.e. 50��.Figure 2.Outline of the scattering coefficients measurements for the MQCM device, represented as a four-ports network (on the left).

The scattering matrix (on the right) is characterized by 10 independent parameters, since the matrix is reciprocal (i.e. sij=s …The resulting scattering parameters are plotted in Figure 3 and and4.4. The absolute values of the reflection parameters point out the good separation of the four channels in the frequency range of interest, while the moduli of the transmission parameters, showing typical values of less than -60 dB, indicate the low existing channel-to-channel crosstalk, always less than -40 dB [16]. This result ensures that the channels oscillate almost independently on each others.Figure 3.Moduli of the reflection parameters of the four ports network corresponding to the MQCM.Figure 4.Moduli of the transmission parameters of the four ports network corresponding to the MQCM.

In order to test the characteristics of the MQCM transducer a chemical sensor has been implemented utilizing a new semiconducting co-polymer, namely poly [phenylacetylene-(co-2-hydroxyethyl methacrylate)] (P(PA/HEMA)), synthesized in the form of monodispersed nanospheres. Entinostat The use of different reaction conditions during the synthesis of this co-polymer allows to modulate dimension, polydispersity and superficial charge of the beads [17].

For turbulent flows, the velocity field can be decomposed into a mean flow and a fluctuati
Small satellites have the advantages of lower costs as well as programmable positioning and sensor modes, and can thus be customized to address environmental monitoring tasks which are challenging for routine commercial satellites. Monitoring of aerosol concentrations as an indicator of air quality at local scale is such a problem due to the need for high temporal, spatial and spectral resolution combined in one sensor. This paper demonstrates that a small satellite CHRIS/PROBA has both the spectral and spatial sensitivity to accurately retrieve aerosols at a detailed level, although its orbit does not offer adequate temporal resolution for continuous monitoring.

There is currently no reliable method for the monitoring of air quality over urban areas using remote sensing. Methodologies by Tanr�� et al. [1], Sifakis et al. [2], Kaufman and Tanr�� [3], Hsu et al. [4] do not provide consistent results over spatially complex regions due to inadequate spatial and temporal resolution combined with a lack of suitable algorithms. Batimastat Furthermore there has been little effort to map air quality at detailed level. According to Li et al. [5], aerosols over a 50 km2 domain do not vary much, except over regions near major emission sources, and most previous remote sensing studies have not addressed variability in air quality at fine resolution.

Thus the MODIS standard Aerosol product MOD04 is at the coarse resolution Entinostat of 10 km. Hsu et al.’s [4] deep blue algorithm, which requires two blue bands (eg.

MODIS 412 nm and 470 nm bands) for AOT retrieval over bright surfaces has only been demonstrated successfully for large homogeneous surfaces such as deserts, but not for areas of complex land cover. The differential texture analysis method of Sifakis et al. [6] and Retalis et al. [7] operates at coarse resolutions of ca. 500 m due to the need for a large kernel size for texture analysis. The method has not been validated empirically due to the lack of AOT validation data, and it suffers from land cover changes over time which is common in human-dominated landscapes.

In Hong Kong, air quality modeling by the Environmental Protection Department (EPD) suffers from the distant location and uncertainty of the data sources outside Hong Kong, making model output at resolutions higher than 1.5 km meaningless. Even at this coarse resolution very little variation in air quality over the 1,060 km2 of Hong Kong’s territory is evident, although data from the 14 ground stations suggests substantial spatial variation [8].