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[en] The accuracy of the quantitative sensing of volatile organic compounds by chemoresistive gas sensors suffers from the fluctuations in the background atmospheric conditions. This is caused by the drift-like terms introduced in the responses by these instabilities, which should be identified and compensated. Here, a mathematical model is presented for a specific chemoresistive gas sensor, which facilitates these identification and compensation processes. The resistive gas sensor was considered as a multi-input-single-output system. Along with the steady state value of the measured sensor resistance, the ambient humidity and temperature are the inputs to the system, while the concentration level of the target gas is the output. The parameters of the model were calculated based on the experimental database. The model was simulated by the utilization of an artificial neural network. This was connected to the sensor and could deliver the correct contamination level upon receiving the measured gas response, ambient humidity and temperature.
[en] The data centre at the Galician Institute of High Energy Physics (IGFAE) of the Santiago de Compostela University (USC) is a computing cluster with about 150 nodes and 1250 cores that hosts the LHCb Tiers 2 and 3. In this small data centre, and of course in similar or bigger ones, it is very important to keep optimal conditions of temperature, humidity and pressure. Therefore, it is a necessity to monitor the environment and be able to trigger alarms when operating outside the recommended settings. There are currently many tools and systems developed for data centre monitoring, but until recent years all of them were of commercial nature and expensive. In recent years there has been an increasing interest in the use of technologies based on Arduino due to its open hardware licensing and the low cost of this type of components. In this article we describe the system developed to monitor IGFAE's data centre, which integrates an Arduino controlled sensor network with the Nagios monitoring software. Sensors of several types, temperature, humidity and pressure, are connected to the Arduino board. The Nagios software is in charge of monitoring the various sensors and, with the help of Nagiosgraph, to keep track of the historic data and to produce the plots. An Arduino program, developed in house, provides the Nagios plugin with the readout of one or several sensors depending on the plugin's request. The Nagios plugin for reading the temperature sensors also broadcasts an SNMP trap when the temperature gets out of the allowed operating range.
[en] Highlights: • Triboelectric nanogenerator was prepared using force-assembled colloidal arrays. • The electrical performance was determined by the structures and colloidal size. • They displayed high electric output, stability, and humidity resistance. We introduce a novel, robust, cost-effective, and scalable approach for the preparation of a large-area force-assembled triboelectric nanogenerator (FTENG), which allows a stable and high electric output under a wide range of humidity conditions through its dual-sized morphology (i.e., microstructures and nanostructures). In this study, hexagonally packed colloidal arrays prepared by a force assembly approach rather than by conventional self-assembly were used as a mold for a triboelectric poly(dimethylsiloxane) (PDMS) replica with desired pattern shapes (intaglio and embossed structures) and sizes. The morphological size of the PDMS films was determined by the diameter of the force-assembled colloids. The electrical output performance of FTENGs composed of electrodes and a PDMS film increased substantially as the size of the micropores (for intaglio-structured PDMS) or embossed features (for embossed-structured PDMS) decreased. Furthermore, the triboelectric PDMS film with micro-/nanosized features (i.e., dual-embossed PDMS) displayed a remarkable electrical output of 207 V (open-circuit voltage under a compressive force of 90 N in relative humidity (RH) of 20%) and high hydrophobicity compared to that of PDMS films with flat, intaglio or embossed structures. This device maintained a high electric output even in a high-humidity environment (i.e., open-circuit output voltage ~175 V in RH 80%). Our approach using force-assembly and hierarchical surface morphology will provide a novel and effective framework for developing strong power sources in various self-powered electronics.
[en] The author surveys briefly the various factors that are to be considered in predicting the reliability of electronic instruments. Theoretical aspects of reliability are briefly described. Practical methods such as reliability prediction, redundancy, debugging and maintainability to achieve high reliability are enumerated. Effects of temperature and humidity on electronic components in general are discussed. Adverse effects of climatic conditions on nuclear electronic instruments are described and means to overcome them are suggested. Finally, the author expresses simple and inexpensive techniques to achieve high reliability. (author)
[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] To know the importance of different climate variables on reference crop evapotranspiration (ETo), a step-by-step sensitivity analysis of ETo to single, two, and multi-climate variables (C) was conducted. ETo in north, south, and entire Xinjiang Province, China, over 1961–2013 was estimated using the Penman-Monteith equation. Trends in the involved six Cs (i.e., minimum temperature—Tmin, average temperature—Tave, maximum temperature—Tmax, wind speed at 2 m—U2, sunshine hour—n, and relative humidity—RH) were detected by the modified Mann-Kendall test. Nineteen scenarios of changed Cs were preset to obtain recalculated ETo values considering the actual trend in each C and the Pearson’s correlation relationship between ETo and Cs. The results showed that ETo was mostly sensitive to Tmax, U2, and n. Sensitivity of ETo to the two overlapped changes of Tmin and Tmax caused larger increases in ETo than Tmax and Tave, Tave and Tmax, Tmax and (−n), Tmax and RH, Tmax and (−U2), and Tmin and Tave, but the overlapped changes (−U2) and (−n) caused larger decreases in ETo than the other two C scenarios. The simultaneously increased Tmax, Tmin, Tave, and RH plus decreased U2 and n had caused the actual decreases in ETo in Xinjiang. In general, the effects of decreased U2 and n on decreasing ETo compensated the effects of increased Tmax on decreasing ETo in Xinjiang.
[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 paper presents a humidity sorption sensor made with an ink-jet printing technique. Nafion was applied as a humidity sorption material. After the presentation of sensor construction and sensor fabrication technology, a lot of effort has been made for detailed sensor tests and characterization. The sensor model based on a RC transmission line with distributed parameters (Jachowicz and Senturia 1981/1982 Sensors Actuators 2 171–86) has been carefully described and validated by a comparison with the sensor empirical parameters, measured in a broad range of measurement frequencies. On the basis of achieved results, some general conclusions for humidity sorption sensors on both the sensor fabrication technology and the sensor modelling have been made and presented in this paper
[en] This paper presents a study of feasibility of different existing methodologies linked to field's data acquisition from remote meteorological stations. The data transmission serves to collect field's meteorological information, such as temperature, humidity and radiation. In our study the experimental data is registered in a weather station located about 100 km from University of Almeria. Various existing techniques are studied, especially Radio, GSM (global system of mobile communication) and GPRS (general packet radio service). In the result of these studies has been designed a system of field's data acquisition (herein referred as Meteologger) which we are going to present in this paper. The system is based on an ATmega 16 microcontroller, which scans 8 sensors together at any programmable intervals. This paper presents the study of the mentioned project, application and some main characteristics of the prototype system and its program. We attempt to implement the system, and subsequently present the performance of tests regarding the mentioned system. To verify its functioning some comparison of this measurement system with two others commercial data-acquisition system (Campbell and Hobo H8) has been carried out