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[en] Electrostatic collection technique is widely used in various radon monitors. The mechanism of this kind of radon monitor is that the positive Po particles, produced by decay of radon, can be collected on the surface of detector in electric field. Collection efficiency, therefore, could be affected by air humidity. Calibration under different humidity conditions or test of humidity response is necessary consequently. In this study, a humidity control technique based on Nafion membrane tube (NMT) is developed. Under a consistent flowrate with a certain stable level of radon concentration and humidity of main-path inlet, the humidity of outlet sample gas from the main-path can be adjusted and stably controlled at a certain level by changing side-path's flowrates of NMT. By adjusting main and side-path flowrate, RH of outlet gas of the main-path can be controlled from 5.3 to 80.0%. Theoretical study were also performed. Based on this, humidity influence calibration of an electrostatic radon monitor was performed, and a relationship between the sensitivity of the radon monitor and relative humidity was obtained. (authors)
[en] This paper investigates monthly, seasonal, and annual trends in rainfall, streamflow, temperature, and humidity amounts at Urmia lake (UL) basin and analyzes the interaction between these variables and UL’s water level fluctuation during the 1971–2013 period. Two new methods including nonparametric hybrid wavelet Mann–Kendall test and Şen’s methodology have been used to determine potential trends in the variables and their dominant periods. The results showed significant decreasing trends in the water level and streamflow series, moderate decreasing trend in the rainfall and relative humidity series, and increasing trends in the observed temperature data. The 8- , 12-month, and 2-year periods were detected as the dominant periods of the variables in monthly, seasonal, and annual timescales, respectively. The results from the interaction analysis revealed that the main factor influencing the water level at UL is decreasing trend in the streamflow series. Both the monthly series of UL’s water level and the streamflow series of the stations indicated two start points of significant decreasing trend in 1973 and 1998. Furthermore, a comparative analysis among the applied methods indicated a good agreement between the results of hybrid wavelet Mann–Kendall test and Şen’s trend analyzing method.
[en] Abstract Background: Relative humidity (RH) is one of the key environmental parameters in many experimental processes, and RH control is particularly important for in-situ synchrotron radiation experiments. However, there is no suitable commercial RH control equipment available for such experiments. Purpose: Based on the dynamic control of microcontroller, this study aims to develop an integrated set of numerically controlled (NC) RH control device, which can be conveniently loaded on the synchrotron radiation end-stations. Methods: A moisture channel and another dry air channel are connected to the sample chamber for humidification and dehumidification respectively. The dynamic equilibrium of RH at various values is controlled by the microcontroller using a fuzzy algorithm. Results: This device can hold the RH with an error of ± 1.0% at any set value from 20% to 94%. It also can increase the RH from 20% to 90% and decrease the RH from 90% to 20% with an error of ± 1.5% at a constant speed. Conclusion: This device can provide RH controlling environment with three switchable operation modes including RH holding, increasing and decreasing. It can meet various requirements of humidity control in kinds of synchrotron radiation in-situ experiments. (authors)
[en] In this paper, the effect of humidity conditions on thermal buckling analysis of graphene system contained two layers under different boundary conditions is investigated. The two-variable shear deformation plate theory is employed with the nonlocal continuum theory to deduce the governing stability equations. These equations are solved analytically to obtain the thermal buckling of the nanoplate system with simply supported, clamped and free boundary conditions. The present system of double-layered graphene sheets is composed from two sheets of graphene joined together by an elastic medium and hedged by two-parameter foundations. The external foundations are modeled as Winkler–Pasternak model. Two characteristic types of thermal buckling are considered: synchronous and asynchronous modes of buckling. The temperature rise and moisture concentration are assumed as a fixed, linear or nonlinear function of z (along the thickness direction). For the validation of the formulations, the present results are compared with those published in the references. Furthermore, the influences of the nonlocal parameter, humidity and other parameters on thermal buckling of double-layered graphene system are all discussed. (paper)
[en] Highlights: • Shrinkage of concrete is measured with various temperature and humidity conditions. • The fib MC2010 shrinkage model is accurate for low RH and high T conditions. • The fib MC2010 shrinkage model slightly underestimate for other conditions. • The fib MC2010 creep model conservatively predicts creep strains. - Abstract: Creep and shrinkage of concrete is influenced by many factors including relative humidity and temperature. The combined effect of low relative humidity (<20%) and high temperature (38 °C) on creep and shrinkage of concrete is uncertain as limited tests have been conducted in this domain. Also unknown is the ability of the fib MC2010 model code in predicting the shrinkage and creep at the environment. This paper presents the results of experiments conducted in which concrete was cast and exposed to the aforementioned environmental conditions. The shrinkage and creep behaviour of the concrete was observed for 110 days, and experimental results were compared with predicted values using fib MC2010 model code.
[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] Many animals move within ground composed of granular media (GM); the resistive properties of such substrates can depend on water content and compaction, but little is known about how such parameters affect locomotion or the physics of drag and penetration. Using apparatus to control compaction of GM, our recent studies of movement in dry GM have revealed locomotion strategies of specialized dry-sand-swimming reptiles. However, these animals represent a small fraction of the diversity and presumed burial strategies of fossorial reptilian fauna. Here we develop a system to create states of wet GM of varying moisture content and compaction in quantities sufficient to study the burial and subsurface locomotion of the Ocellated skink (C. ocellatus), a generalist lizard. X-ray imaging revealed that in wet and dry GM the lizard slowly buried ( s) propagating a wave from head to tail, while moving in a start-stop motion. During forward movement, the head oscillated, and the forelimb on the convex side of the body propelled the animal. Although body kinematics and ‘slip’ were similar in both substrates, the burial depth was smaller in wet GM. Penetration and drag force experiments on smooth cylinders revealed that wet GM was more resistive than dry GM. In total, our measurements indicate that while the rheology of the dry and wet GM differ substantially, the lizard's burial motor pattern is conserved across substrates, while its burial depth is largely constrained by environmental resistance. (paper)
[en] The interannual variability of typhoon onset date in western North Pacific (WNP) during 1979–2015 is investigated. The average date in the earlier (later) onset group is early April (late July). A diagnosis of the genesis potential index shows that the key factor affecting the earlier and later onset lies in the background moisture field. According to their evolution feature, the earlier onset cases are further divided into two sub-groups. In the first sub-group, positive specific humidity anomalies were confined in the western WNP and caused primarily by circulation anomalies associated with a La Niña in the equatorial eastern Pacific. In the second sub-group, positive specific humidity anomalies were confined in the eastern WNP and caused by anomalous convection associated with the Pacific Meridional Mode (PMM) in the tropical and subtropical eastern Pacific. In the later onset composite, negative specific humidity anomalies appear in the WNP, and were accompanied by an anomalous anticyclone in situ and a V-shape negative SSTA pattern in the western Pacific. In addition, the change of background vertical wind shear (VWS) also influences the TC onset date. A decrease (increase) in the VWS magnitude and an easterly (westerly) shear anomaly occur in the earlier (later) onset composite. Physically it is argued that both the magnitude of the VWS and the sign of anomalous zonal wind shear may affect TC formation in the WNP.
[en] LnFeO3 (Ln = Sm, Nd, La) nanofibers are synthesized via electrospinning and the humidity sensors based on LnFeO3 nanofibers are fabricated and measured at different relative humidity to investigate the humidity sensing properties. The optimal working frequency of LnFeO3 nanofibers humidity sensors are all 100 Hz at which the sensors are of good linearity and high response. Compared with other LnFeO3 nanofibers humidity sensors, SmFeO3 nanofibers humidity sensor shows the best sensitivity and the impedance variation is more than five orders of magnitude with the relative humidity changing from 11% to 95%. The response time is about 10 s and the impedance versus RH curve is of good linearity. (The linear correlation coefficient is 0.98.) The results indicate that the SmFeO3 nanofibers with low Ln–O binding energy exhibit the best humidity sensing properties compared with others. We expect that our work has a great significance for fabricating high-performance humidity sensors. (paper)