We report here the development of a compact, open-path CO2 and H2O sensor based on the newly introduced scanned-wavelength modulation spectroscopy with the first harmonic phase angle (scanned-WMS-θ1f) method for high-sensitivity, high temporal resolution, ground-based measurements. The considerable advantage of the sensor, compared with existing commercial ones, lies in its fast response of 500 Hz that makes this instrument ideal for resolving details of high-frequency turbulent motion in exceptionally dynamic coastal regions. The good agreement with a commercial nondispersive infrared analyzer supports the utility and accuracy of the sensor. Allan variance analysis shows that the concentration measurement sensitivities can reach 62 ppb CO2 in 0.06 s and 0.89 ppm H2O vapor in 0.26 s averaging time. Autonomous field operation for 15-day continuous measurements of greenhouse gases (CO2/H2O) was performed on a shore-based monitoring tower in Daya Bay, demonstrating the sensor’s long-term performance. The capability for high-quality fast turbulent atmospheric gas observations allow the potential for better characterization of oceanographic processes.
Trust is the foundation of interpersonal relationship and interaction as in social networks as in real world. Previous researches about the trust between users mainly focus on nonadjacent users in social networks, where the trust between adjacent users is assumed to be known. However, in most social networks, the trust between adjacent users is unknown, that limits the applications of those nonadjacent users trust models. In this paper, we propose an adjacent users trust measurement model(AUTrust) and discuss how to construct a trust social network with AUTrust. The factors affecting trust between users could be classified into three dimensions: (i) similarity between users, (ii) familiarity between users, (iii) users' social reputation. The last two dimensions can be used to reflect asymmetry of trust between users. Then we discuss the methods of quantifying trust with these dimensions. Users' information that AUTrust needs can be collected with API provided by social networks, so the model can be widely applied to social networks. Finally, we evaluated the model on 10-million-level Ten cent Weibo dataset, and the experiment proves the practicability and universality of AUTrust model.
Robust marine carbon sensors with small size, low power consumption, and high sensitivity provide greater insight into the carbon cycle studies and resolve environmental variability. We report here the development of a diminutively integrated tunable diode laser absorption spectroscopy (TDLAS) system with a specially designed multipass gas cell for small amounts of dissolved gas extractions and measurements. It was used to detect and monitor carbon dioxide (CO2) dissolved in water and seawater. Systematic experiments have been carried out for system evaluation in the lab. Extracted CO2 was determined via its 4989.9 cm−1 optical absorption line. The achieved TDLAS measurement precision was 4.18 ppm for CO2, measured by averaging up to 88 s. The integrated absorbance was found to be linear to gas concentrations over a wide range. Comparison measurements of the atmospheric CO2 values with a commercial instrument confirmed a good accuracy of our TDLAS-based system. The first test campaign was also accomplished with a hollow fiber membrane contactor, and concentrations of CO2 were quantitatively detected with partial degasification operations. The results clearly show the ability to continuously measure dissolved gases and highlight the potential of the system to help us better understand physical and geochemical processes in a marine environment.