Results 1 - 10 of 374
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[en] A common coldrex, paracetamol, was used as humidity sensing material. The capacitance-type humidity sensor was fabricated by aerosol deposition method. The humidity sensitive properties were investigated through dielectric measurements. Our results reveal that the sensor has exciting performances in high relative humidity. Both −OH and −NH groups have contributions to water absorption. The −OH groups lead to a water-containing surface layer giving rise to pronounced Maxwell-Wagner response, which in turn, yields the humidity response that can be easily adjusted by an external electric field. This work indicates that the paracetamol is a promising humidity sensing material. (paper)
[en] Soil moisture (SM) feedback on climate variables especially temperature is an important aspect in land-atmosphere coupling. Based on the Global Land Data Assimilation System (GLDAS) V2.0 SM data and the gridded observational temperature data, we statistically analyze the thermal feedback of SM over North China (NC). The results show that SM exerts a decreasing trend under the background of evident warming over NC, inducing a decadal enhancement of SM feedbacks on the local temperature and extreme hot events. The SM feedback contributes 6% of the total air temperature variation during 1961–2012, while it reaches 36% after the regional warming during 1994–2012. Such SM affecting temperature is mainly reflected in its feedback on daily maximum temperature, which is also intensified during the warm period. The decadal intensification is also found in the feedback of SM on hot extremes. Further analyses show that the abnormal changes of the latent and sensible heat fluxes caused by the SM anomaly are the main reasons that affect the thermal conditions. Besides, the rising Bowen ratio indicates that upward thermal transfer on the land surface is enhanced in recent years, which suggests that the atmosphere is more sensible to the abnormal heating on the ground. This consequently translates into the decadal intensification of the local thermal feedback of SM in summer over NC.
[en] Reliable tools for monitoring heat and moisture exchanger (HME) performance are in high demand by physicians, in order to assess the proper air conditioning delivered to intensive care unit (ICU) patients undergoing mechanical ventilation. To date, there is no system that comprehends all the requirements for clinical applications, in terms of performance and design. In this paper, a compact measurement system is proposed for monitoring HME performance in vivo, comparing the results with in vitro testing outcomes. The portable system presented is connected to the ventilation circuit close to the HME and assures wide compatibility with the new generation of smart devices because of its embedded Bluetooth low-energy module. Low power consumption ensures long-term monitoring capability of more than 24 h. Laboratory tests performed both in static and dynamic conditions showed rise- and fall-times for humidity measurements between 1 s and 1.8 s, compatible with many common variations in working operative conditions during mechanical ventilation. Clinical tests performed in the ICU demonstrated the possibility to effectively and continuously monitor in vivo HME performance. Furthermore, the comparison of the in vivo performances with the in vitro standard procedure and the agreement of the parameter ranges monitored allowed us to confirm the reliability of the system, highlighting the usefulness of this approach for proper real time HME monitoring. (paper)
[en] This work presents the computational evaluation of a new model for relative humidity sensor based on the principle of intermodal interference using a square-section no-core tapered optical fiber compared to a classical cylindrical tapered optical fiber sensor. Attempting at a new application of this type of sensor, simulations were carried out in the range of up to 60% of relative humidity, the main interest range of the pharmaceutical industry. Several materials were used in its modeling and an analysis was developed in its constructive dimensions, in order to verify the influence of each of them on the sensor performance.
[en] Recently, the humidity sensors have captivated huge attention for making human life more comfortable and to diagnose several diseases. Here, we reported the excellent humidity responsiveness of V0.5Sn0.5Se2 ternary alloy for human breath monitoring and touchless positioning interface. The resistive sensor based on direct vapour transport grown bulk crystal of V0.5Sn0.5Se2 ternary alloy is fabricated and explored for its static response in different humidity levels ranging from 20 to 90%. The sensor showed excellent dynamic switching characteristics between relative humidity of 20% and 90% with responsivity of 6.78%, response time of 3.2 s and recovery time of 2.3 s. Subsequently, the sensor is exploited for giant responsiveness for human breath monitoring and words recognitions. The sensor exhibited quite distinct response towards different words namely, “Pratik”, “Chetan” and “Mohit”. Besides, novel touch-less positioning interface is explained with respect to humidity variation. Overall, the results advocate development of resistive sensors for intended humidity, biomedical as well as for intelligent touch-less sensing applications.
[en] Recording high quality biosignals by dry textile electrodes is a common challenge in medical health monitoring garments. The aim of this study was to improve skin–electrode interface and enhance the quality of recorded electrocardiography (ECG) signals by modification of textile electrodes embedded in WearItMed smart garment. The garment has been developed for long-term health monitoring in patients suffering from epilepsy and Parkinson’s disease. A skin-friendly electro-conductive elastic paste was formulated to coat and modify the surface of the knitted textile electrodes. The modifications improved the surface characteristics of the electrodes by promoting a more effective contact area between skin and electrode owing to a more even surface, fewer pores, greater surface stability against touch, and introduction of humidity barrier properties. The modifications decreased the skin–electrode contact impedance, and consequently improved the recorded ECG signals obviously when low pressure was applied to the electrodes, therefore contributed to greater patient comfort. The created contact surface allowed the natural humidity of the skin/sweat to ease the signal transfer between the electrode and the body, while introducing a shorter settling time and retaining moisture over a longer time. Microscopic images, ECG signal measurements, electrode–skin contact impedance at different pressures and times, and water absorbency were measured and reported.
[en] In spite of extensive investigation and applications, influence of oxygen (O), and humidity on polyaniline (PANI) behaviour is not well understood. For this reason we have performed semi-empirical quantum mechanics, and ab-initio calculations of the pernigraniline base (PNB) PANI oligomers, of various lengths, before and after approach of H2O, O2 , and hydroxyl (OH −) group, and attachment of OH − and O to various molecular positions. Structure, charge and electrostatic potential distribution, relevant energies and enthalpies, infrared and electronic spectra of the PNB tetramer equilibrium conformation, and their changes induced by specific OH − , and O attachments are determined. These results provide identification of the most probable positions for O2 and H2O approach to PNB_PANI, enthalpies of OH − and O attachments to them, changes of molecular properties induced by the attachments, and infrared and electronic modes that are most suitable for the attachments detection. The results are compared to the existing experimental data, and the results of similar calculations, and implications for the PNB_PANI applications are notified. © 2019 Elsevier B.V.
[en] The objective of this study is to develop a simulation model of polymer desorption under on-car experimental conditions, which is one of the main factors in condensation phenomena for automotive headlamp, and to verify its accuracy by comparison with experimental results. The numerical model is composed of the species transport equation for absolute humidity, and the water film thickness equation for evaporation and condensation. To apply the temperature boundary conditions on the walls inside the headlamp as the on-car test conditions, a time-dependent average temperature is utilized to simplify the numerical simulation. The Arrhenius type flux obtained using the Karl– Fischer Titration instrument is used for the polymer desorption on the headlamp walls for the species transport equation. The numerical average absolute humidity is compared with the experimental absolute humidity taken at a specific location. The results showed that the absolute humidity decreases sharply, i.e., when condensation occurs inside the headlamp, at the same time in the simulations and experiments.
[en] This study investigates, for the purpose of fog forecasting, the impacts of topography and land use changes on the characteristics of turbulence that directly contribute to the formation and dissipation of fog off the west coast of the Korean Peninsula using the Weather Research and Forecasting model version 3.5.1. During the investigation period, there are 59 coastal ground fog and 29 sea fog events. Local meteorological characteristics of coastal ground fog were similar to those of radiation fog typically seen over the land surface since the reclaimed island was constructed. After the sun rises, relative humidity over the land surface decreases rapidly—within a couple of hours—due to surface heating, which is controlled directly by shortwave radiation. Over the sea surface, however, the sea fog remains, with the relative humidity higher than 95% even during the daytime. For two selected cases, topography and land use were modified to identify turbulence characteristics through numerical modeling. This modification contributed to better forecasting the formation and dissipation of fog by changing characteristics of sensible and latent heat flux in the land surface model and then planetary boundary layer over the reclaimed island.
[en] The differences in planetary boundary layer characteristics, in particular atmospheric boundary layer height (ABLH), humidity, and local circulations in pre-monsoon and monsoon period over the Erhai Lake, were simulated by the lake-atmosphere coupled model WRF v3.7.1. No lake simulations were also conducted to investigate lake effects over complex topography. During pre-monsoon period, local circulation was fully developed under weak synoptic system. The ABLH ran up to 2300 m or so. During monsoon period, temperature difference between land and lake became smaller, resulting in weaker local circulations. The height of circulation reduced by 500 m, and ABLH ran up to 1100 m during the day. Enhanced soil moisture and low surface temperature due to monsoon rainfalls in July could be the main reason for the slightly lower ABLH over the Erhai Lake area. Specific humidity of the boundary layer increased 8.8 g kg−1 or so during monsoon period. The Erhai Lake enlarged thermal contrast between valley and mountain slope in the Dali Basin. The lake reduced air temperature by 2~3 °C during daytime and increased air temperature by nearly 2 °C in the evening. Due to its small roughness length and large thermal capacity, the Erhai Lake enlarged lake-land temperature difference and local wind speed. A cyclonic circulation was maintained by the combination of mountain breeze and land breeze in the south of the lake. The lake decreased air temperature, increased specific humidity, and reduced ABLH during daytime, whereas the opposite effect is presented at night.