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1
Pokrovski, Gleb S., Jacques Roux, and Jean-Claude Harrichoury. "Fluid density control on vapor-liquid partitioning of metals in hydrothermal systems." Geology 33, no. 8 (August 1, 2005): 657–60. http://dx.doi.org/10.1130/g21475ar.1.
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Abstract Hot aqueous fluids, both vapor and saline liquid, are primary transporting media for metals in hydrothermal-magmatic systems. Despite the growing geological evidence that the vapor phase, formed through boiling of magmatic ore-bearing fluids, can selectively concentrate and transport metals, the physical-chemical mechanisms that control the metal vapor-liquid fractionation remain poorly understood. We performed systematic experiments to investigate the metal vapor-liquid partitioning in model water-salt-gas systems H2O-NaCl-KCl-HCl at hydrothermal conditions. Measurements show that equilibrium vapor-liquid fractionation patterns of many metals are directly related to the densities of the coexisting vapor and liquid phases. Despite differences in the vapor-phase chemistry of various metals that form hydroxide, chloride, or sulfide gaseous molecules of contrasting volatile properties, water-solute interaction is a key factor that controls the metal transfer by vapor-like fluids in Earth's crust. These findings allow quantitative prediction of the vapor-liquid distribution patterns and vapor-phase metal transport in a wide range of conditions. Our density model accounts well for the vapor-brine distribution patterns of Na, Si, Fe, Zn, As, Sb, and Ag observed in fluid inclusions from magmatic-hydrothermal deposits. For Au and Cu, the partitioning in favor of the liquid phase, predicted in a sulfur-free system, contrasts with the copper and gold enrichment observed in natural vapor-like inclusions. The formation of stable complexes of Cu and Au with reduced sulfur may allow for their enhanced transport by sulfur-enriched magmatic-hydrothermal vapors.
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Konyukhov, V. K., and N. I. Valentinova. "Transfer of water molecules in presence of low density water vapor." Journal of Physics: Conference Series 1560 (June 2020): 012018. http://dx.doi.org/10.1088/1742-6596/1560/1/012018.
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Song, Kun, Xichuan Liu, Taichang Gao, and Peng Zhang. "Estimating Water Vapor Using Signals from Microwave Links below 25 GHz." Remote Sensing 13, no. 8 (April 7, 2021): 1409. http://dx.doi.org/10.3390/rs13081409.
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Water vapor is a key element in both the greenhouse effect and the water cycle. However, water vapor has not been well studied due to the limitations of conventional monitoring instruments. Recently, estimating rain rate by the rain-induced attenuation of commercial microwave links (MLs) has been proven to be a feasible method. Similar to rainfall, water vapor also attenuates the energy of MLs. Thus, MLs also have the potential of estimating water vapor. This study proposes a method to estimate water vapor density by using the received signal level (RSL) of MLs at 15, 18, and 23 GHz, which is the first attempt to estimate water vapor by MLs below 20 GHz. This method trains a sensing model with prior RSL data and water vapor density by the support vector machine, and the model can directly estimate the water vapor density from the RSLs without preprocessing. The results show that the measurement resolution of the proposed method is less than 1 g/m3. The correlation coefficients between automatic weather stations and MLs range from 0.72 to 0.81, and the root mean square errors range from 1.57 to 2.31 g/m3. With the large availability of signal measurements from communications operators, this method has the potential of providing refined data on water vapor density, which can contribute to research on the atmospheric boundary layer and numerical weather forecasting.
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Wang, H., X. Liu, K. Chance, G. González Abad, and C. Chan Miller. "Water vapor retrieval from OMI visible spectra." Atmospheric Measurement Techniques 7, no. 6 (June 30, 2014): 1901–13. http://dx.doi.org/10.5194/amt-7-1901-2014.
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Abstract. There are distinct spectral features of water vapor in the wavelength range covered by the Ozone Monitoring Instrument (OMI) visible channel. Although these features are much weaker than those at longer wavelengths, they can be exploited to retrieve useful information about water vapor. They have an advantage in that their small optical depth leads to fairly simple interpretation as measurements of the total water vapor column density. We have used the Smithsonian Astrophysical Observatory (SAO) OMI operational retrieval algorithm to derive the slant column density (SCD) of water vapor using the 430–480 nm spectral region after extensive optimization. We convert from SCD to vertical column density (VCD) using the air mass factor (AMF), which is calculated using look-up tables of scattering weights and assimilated water vapor profiles. Our Level 2 product includes not only water vapor VCD but also the associated scattering weights and AMF. In the tropics, our standard water vapor product has a median SCD of 1.3 × 1023 molecules cm−2 and a median relative uncertainty of about 11%, about a factor of 2 better than that from a similar OMI algorithm that uses a narrower retrieval window. The corresponding median VCD is about 1.2 × 1023 molecules cm−2. We have examined the sensitivities of SCD and AMF to various parameters and compared our results with those from the GlobVapour product, the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic NETwork (AERONET).
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Wang, H., X. Liu, K. Chance, G. Gonzalez Abad, and C. Chan Miller. "Water vapor retrieval from OMI visible spectra." Atmospheric Measurement Techniques Discussions 7, no. 1 (January 22, 2014): 541–67. http://dx.doi.org/10.5194/amtd-7-541-2014.
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Abstract. There are distinct spectral features of water vapor in the wavelength range covered by the Ozone Monitoring Instrument (OMI) visible channel. Although these features are much weaker than those at longer wavelengths, they can be exploited to retrieve useful information about water vapor. They have an advantage in that their small optical depth leads to fairly simple interpretation as measurements of the total water vapor column density. We have used the Smithsonian Astrophysical Observatory (SAO)'s OMI operational retrieval algorithm to derive the Slant Column Density (SCD) of water vapor from OMI measurements using the 430–480 nm spectral region after extensive optimization of retrieval windows and parameters. The Air Mass Factor (AMF) is calculated using look-up tables of scattering weights and monthly mean water vapor profiles from the GEOS-5 assimilation products. We convert from SCD to Vertical Column Density (VCD) using the AMF and generate associated retrieval averaging kernels and shape factors. Our standard water vapor product has a median SCD of ~ 1.3 × 1023 molecule cm−2 and a median relative uncertainty of ~ 11% in the tropics, about a factor of 2 better than that from a similar OMI algorithm but using narrower retrieval window. The corresponding median VCD is ~ 1.2 × 1023 molecule cm−2. We have also explored the sensitivities to various parameters and compared our results with those from the Moderate-resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic NETwork (AERONET).
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Kim, Sun Min, Hyun Chul Kim, Chang-Yeoul Kim, Daeho Yoon, and Eunhae Koo. "The Relationship Between Water Transmission Rate and Defects on the Film Based on the Defect Analysis Using Fluorescent Calcein Probe." Journal of Nanoscience and Nanotechnology 20, no. 9 (September 1, 2020): 5469–72. http://dx.doi.org/10.1166/jnn.2020.17619.
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The most critical issue on flexible electronics such as organic solar cell, OLED, and flexible displays, is the protection of core active materials from the degradation by water and oxygen. The water vapor transmission rate (WVTR), the main characteristics of barrier films, is closely related to defect density in inorganic layers constructed in the film. In this study, a calcein fluorescent probe is used to examine the relationship between the water vapor transmission rate (WVTR) and the defect density of the film coated the inorganic oxide layer. By using the fluorescence characteristics of calcein dye molecules, the calcein can be used for the evaluation of water vapor transmission rate. The result shows that the defect density is linearly increasing with the water vapor transmission rate of barrier films. Furthermore, it is shown that the defect density is inversely proportional to the thickness of the inorganic layer of Al2O3. Based on these results, it is suggested that the defect density measurement of the inorganic layer can predict the water vapor transmission rate of the barrier film.
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Mei, Yuan, Weihua Liu, A. A. Migdiov, Joël Brugger, and A. E. Williams-Jones. "CuCl Complexation in the Vapor Phase: Insights from Ab Initio Molecular Dynamics Simulations." Geofluids 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/4279124.
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We investigated the hydration of the CuCl0 complex in HCl-bearing water vapor at 350°C and a vapor-like fluid density between 0.02 and 0.09 g/cm3 using ab initio molecular dynamics (MD) simulations. The simulations reveal that one water molecule is strongly bonded to Cu(I) (first coordination shell), forming a linear [H2O-Cu-Cl]0 moiety. The second hydration shell is highly dynamic in nature, and individual configurations have short life-spans in such low-density vapors, resulting in large fluctuations in instantaneous hydration numbers over a timescale of picoseconds. The average hydration number in the second shell (m) increased from ~0.5 to ~3.5 and the calculated number of hydrogen bonds per water molecule increased from 0.09 to 0.25 when fluid density (which is correlated to water activity) increased from 0.02 to 0.09 g/cm3 (fH2O 1.72 to 2.05). These changes of hydration number are qualitatively consistent with previous solubility studies under similar conditions, although the absolute hydration numbers from MD were much lower than the values inferred by correlating experimental Cu fugacity with water fugacity. This could be due to the uncertainties in the MD simulations and uncertainty in the estimation of the fugacity coefficients for these highly nonideal “vapors” in the experiments. Our study provides the first theoretical confirmation that beyond-first-shell hydrated metal complexes play an important role in metal transport in low-density hydrothermal fluids, even if it is highly disordered and dynamic in nature.
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Ding, Nan, Shubi Zhang, and Qiuzhao Zhang. "New parameterized model for GPS water vapor tomography." Annales Geophysicae 35, no. 2 (February 28, 2017): 311–23. http://dx.doi.org/10.5194/angeo-35-311-2017.
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Abstract. Water vapor is the basic parameter used to describe atmospheric conditions. It is rarely contained in the atmosphere during the water cycle, but it is the most active element in rapid space–time changes. Measuring and monitoring the distribution and quantity of water vapor is a necessary task. GPS tomography is a powerful means of providing high spatiotemporal resolution of water vapor density. In this paper, a spatial structure model of a humidity field is constructed using voxel nodes, and new parameterizations for acquiring data about water vapor in the troposphere via GPS are proposed based on inverse distance weighted (IDW) interpolation. Unlike the density of water vapor that is constant within a voxel, the density at a certain point is determined by IDW interpolation. This algorithm avoids the use of horizontal constraints to smooth voxels that are not crossed by satellite rays. A prime number decomposition (PND) access order scheme is introduced to minimize correlation between slant wet delay (SWD) observations. Four experimental schemes for GPS tomography are carried out in dry weather from 2 to 8 August 2015 and rainy days from 9 to 15 August 2015. Using 14 days of data from the Hong Kong Satellite Positioning Reference Station Network (SatRef), the results indicate that water vapor density derived from 4-node methods is more robust than that derived from that of 8 nodes or 12 nodes, or that derived from constant refractivity schemes and the new method has better performance under stable weather conditions than unstable weather (e.g., rainy days). The results also indicate that an excessive number of interpolations in each layer reduce accuracy. However, the accuracy of the tomography results is gradually reduced with increases in altitude below 7000 m. Moreover, in the case of altitudes between 7000 m and the upper boundary layer, the accuracy can be improved by a boundary constraint.
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Zhao, Qingzhi, Yibin Yao, and Wanqiang Yao. "Troposphere Water Vapour Tomography: A Horizontal Parameterised Approach." Remote Sensing 10, no. 8 (August 7, 2018): 1241. http://dx.doi.org/10.3390/rs10081241.
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Global Navigation Satellite System (GNSS) troposphere tomography has become one of the most cost-effective means to obtain three-dimensional (3-d) image of the tropospheric water vapour field. Traditional methods divide the tomography area into a number of 3-d voxels and assume that the water vapour density at any voxel is a constant during the given period. However, such behaviour breaks the spatial continuity of water vapour density in a horizontal direction and the number of unknown parameters needing to be estimated is very large. This is the focus of the paper, which tries to reconstruct the water vapor field using the tomographic technique without imposing empirical horizontal and vertical constraints. The proposed approach introduces the layered functional model in each layer vertically and only an a priori constraint is imposed for the water vapor information at the location of the radiosonde station. The elevation angle mask of 30° is determined according to the distribution of intersections between the satellite rays and different layers, which avoids the impact of ray bending and the error in slant water vapor (SWV) at low elevation angles on the tomographic result. Additionally, an optimal weighting strategy is applied to the established tomographic model to obtain a reasonable result. The tomographic experiment is performed using Global Positioning System (GPS) data of 12 receivers derived from the Satellite Positioning Reference Station Network (SatRef) in Hong Kong. The quality of the established tomographic model is validated under different weather conditions and compared with the conventional tomography method using 31-day data, respectively. The numerical result shows that the proposed method is applicable and superior to the traditional one. Comparisons of integrated water vapour (IWV) of the proposed method with that derived from radiosonde and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim data show that the root mean square (RMS)/Bias of their differences are 3.2/−0.8 mm and 3.3/−1.7 mm, respectively, while the values of traditional method are 5.1/−3.9 mm and 6.3/−5.9 mm, respectively. Furthermore, the water vapour density profiles are also compared with radiosonde and ECMWF data, and the values of RMS/Bias error for the proposed method are 0.88/0.06 g/m3 and 0.92/−0.08 g/m3, respectively, while the values of the traditional method are 1.33/0.38 g/m3 and 1.59/0.40 g/m3, respectively.
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Xi, Erte, Sean M. Marks, Suruchi Fialoke, and Amish J. Patel. "Sparse sampling of water density fluctuations near liquid-vapor coexistence." Molecular Simulation 44, no. 13-14 (April 21, 2018): 1124–35. http://dx.doi.org/10.1080/08927022.2018.1457218.
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Van Den Bulck, E. "Isotherm correlation for water vapor on regular-density silica gel." Chemical Engineering Science 45, no. 5 (1990): 1425–29. http://dx.doi.org/10.1016/0009-2509(90)87138-i.
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Sokratov, Sergey A., Atsushi Sato, and Yasushi Kamata. "Water vapor in the pore space of snow." Annals of Glaciology 32 (2001): 51–58. http://dx.doi.org/10.3189/172756401781819111.
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AbstractWater vapor in snow is responsible for two main processes connected to almost all studies where snow cover is involved: the snow-density change with time and snow recrystallization. Both processes are the result of a balance between evaporation and condensation on individual snow-crystal surfaces. However, such micro-scale mass balance has rarely been considered as a component of “macro-” heat and mass transfer in snow cover. The present work is an attempt to find a way of combining these two mass-exchange processes, as occurs in Nature. Density change and snow recrystallization rates are analyzed based on recently published temperature field observations around individual snow crystals, combined with experimental data on temperature distributions and recrystallization rates in snow under applied temperature gradients.
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Dong Fu and Xiao-Sen Li. "Investigation of Vapor−Liquid Nucleation for Water and Heavy Water by Density Functional Theory." Journal of Physical Chemistry C 111, no. 37 (August 29, 2007): 13938–44. http://dx.doi.org/10.1021/jp073971a.
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Yasuda, T., M. Miyama, and H. Yasuda. "Dynamic Water Vapor and Heat Transport through Layered Fabrics." Textile Research Journal 62, no. 4 (April 1992): 227–35. http://dx.doi.org/10.1177/004051759206200407.
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Dynamic water vapor and heat transport in the transient state was investigated for fabrics made of polyester, acrylic, cotton, and wool fibers. The overall dissipation rate of water vapor depends on both the vapor transport rate and the vapor absorption by fibers, which are mutually interrelated. Water vapor transport is governed by the vapor pressure gradient that develops across a fabric layer. When a fabric is subjected to given environmental conditions, the actual water vapor transport rate greatly differs depending on the nature of the fibers, even when other parameters are nearly identical, such as density, porosity, and thickness. The actual differential vapor pressure that develops across a layer depends on the water vapor absorption characteristics of the fibers. The higher the water vapor absorption rate, the lower the differential vapor pressure for water vapor transport and thus the lower the overall water vapor transport rate. However, the water vapor transport rate (when considering the actual differential vapor pressure across a fabric layer) is nearly identical regardless of fiber type, providing the fabric structures are kept nearly the same. Water vapor transport occurs through the open air spaces confined by fibers, and the nature of fibers does not greatly affect the characteristic vapor transport rate through these spaces. The temperature of the air space between two layers of fabric rises when water vapor transport occurs. This rise is nearly proportional to the water vapor absorption rate of a fabric, which is determined by the chemical nature of the constituent fibers.
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Ye, Shirong, Pengfei Xia, and Changsheng Cai. "Optimization of GPS water vapor tomography technique with radiosonde and COSMIC historical data." Annales Geophysicae 34, no. 9 (September 20, 2016): 789–99. http://dx.doi.org/10.5194/angeo-34-789-2016.
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Abstract. The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in numerical weather prediction. GPS tomography technique has been proved effectively for three-dimensional water vapor reconstruction. In this study, the tomography processing is optimized in a few aspects by the aid of radiosonde and COSMIC historical data. Firstly, regional tropospheric zenith hydrostatic delay (ZHD) models are improved and thus the zenith wet delay (ZWD) can be obtained at a higher accuracy. Secondly, the regional conversion factor of converting the ZWD to the precipitable water vapor (PWV) is refined. Next, we develop a new method for dividing the tomography grid with an uneven voxel height and a varied water vapor layer top. Finally, we propose a Gaussian exponential vertical interpolation method which can better reflect the vertical variation characteristic of water vapor. GPS datasets collected in Hong Kong in February 2014 are employed to evaluate the optimized tomographic method by contrast with the conventional method. The radiosonde-derived and COSMIC-derived water vapor densities are utilized as references to evaluate the tomographic results. Using radiosonde products as references, the test results obtained from our optimized method indicate that the water vapor density accuracy is improved by 15 and 12 % compared to those derived from the conventional method below the height of 3.75 km and above the height of 3.75 km, respectively. Using the COSMIC products as references, the results indicate that the water vapor density accuracy is improved by 15 and 19 % below 3.75 km and above 3.75 km, respectively.
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He, Jie Ying, Feng Lin Sun, Sheng Wei Zhang, and Yu Zhang. "The Analysis of Atmospheric Water Vapor Based on Ground-Based Microwave Radiometer." Key Engineering Materials 500 (January 2012): 335–40. http://dx.doi.org/10.4028/www.scientific.net/kem.500.335.
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The paper introduces a widely used atmospheric absorption models: MPM by Liebe in 1989. Using this absorption model, the paper simulates the temperature and humidity weighting functions and brightness temperature according to the different frequencies and bandwidth of the multi-channel ground-based microwave radiometer. The results show that simulated brightness temperatures are very well agreement with the observation values with an acceptable root mean square error. This paper uses widely used retrieval method of artificial neural network to obtain the water vapor density profiles and calculates the root mean square error of each dataset. Also, to improve the accuracy of retrievals, this paper adopts multi-layers neural network which has two hidden layers. The results show that the retrievals of water vapor density profiles based on ground-based microwave radiometer are agreement with the water vapor density profile which is observed by radiosonde. Grant Nos. GYHY200906035 China Meteorological Administration nonprofit sector (meteorology) special research
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Sängerlaub, Kucukpinar, and Müller. "Desiccant Films Made of Low-Density Polyethylene with Dispersed Silica Gel—Water Vapor Absorption, Permeability (H2O, N2, O2, CO2), and Mechanical Properties." Materials 12, no. 14 (July 18, 2019): 2304. http://dx.doi.org/10.3390/ma12142304.
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Silica gel is a well-known desiccant. Through dispersion of silica gel in a polymer, films can be made that absorb and desorb water vapor. The water vapor absorption becomes reversible by exposing such films to a water vapor pressure below that of the water vapor pressure during absorption, or by heating the film. The intention of this study was to achieve a better understanding about the water vapor absorption, permeability (H2O, N2, O2, CO2), and mechanical properties of films with dispersed silica gel. Low-density polyethylene (PE-LD) monolayer films with a nominal silica gel concentration of 0.2, 0.4, and 0.6 g dispersed silica gel per 1 g film (PE-LD) were prepared and they absorbed up to 0.08 g water vapor per 1 g of film. The water vapor absorption as a function of time was described by using effective diffusion coefficients. The steady state (effective) water vapor permeation coefficients of the films with dispersed silica gel were a factor of 2 to 14 (8.4 to 60.2·10−12 mg·cm·(cm²·s·Pa)−1, 23 °C) higher than for pure PE-LD films (4.3·10−12 mg·cm·(cm²·s·Pa)−1, 23 °C). On the other hand, the steady state gas permeabilities for N2, O2, and CO2 were reduced to around one-third of the pure PE-LD films. An important result is that (effective) water vapor permeation coefficients calculated from results of sorption and measured by permeation experiments yielded similar values. It has been found that it is possible to describe the sorption and diffusion behavior of water by knowing the permeability coefficient and the sorption capacity of the film (Peff.≈Seff.·Deff.). The tensile stress changed only slightly (values between 10 and 14 N mm−²), while the tensile strain at break was reduced with higher nominal silica gel concentration from 318 length-% (pure PE-LD film) to 5 length-% (PE-LD with 0.6 g dispersed silica gel per 1 g film).
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Hienola, A. I., H. Vehkamäki, I. Riipinen, and M. Kulmala. "Homogeneous vs. heterogeneous nucleation in water-dicarboxylic acid systems." Atmospheric Chemistry and Physics 9, no. 6 (March 17, 2009): 1873–81. http://dx.doi.org/10.5194/acp-9-1873-2009.
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Abstract. Binary heterogeneous nucleation of water-succinic/glutaric/malonic/adipic acid on nanometer-sized particles is investigated within the frame of classical heterogeneous nucleation theory. Homogeneous nucleation is also included for comparison. It is found that the nucleation probabilities depend on the contact angle and on the size of the seed particles. New thermodynamical properties, such as saturation vapor pressure, density and surface tension for all the dicarboxylic acid aqueous solutions are included in the calculations. While the new surface tension and density formulations do not bring any significant difference in the computed nucleation rate for homogeneous nucleation for succinic and glutaric acids, the use of the newly derived equations for the vapor pressure decrease the acid concentrations in gas phase by 3 orders of magnitude. According to our calculations, the binary heterogeneous nucleation of succinic acid-water and glutaric acid-water – although it requires a 3–4 orders of magnitude lower vapor concentrations than the homogeneous nucleation – cannot take place under atmospheric conditions. On the other hand binary homogeneous nucleation of adipic acid-water systems might be possible under conditions occuring in upper boundary layer. However, a more detailed characterization of the interaction between the surface and the molecules of the nucleating vapor should be considered in the future.
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Hienola, A. I., H. Vehkamäki, I. Riipinen, and M. Kulmala. "Homogeneous vs. heterogeneous nucleation in water-dicarboxylic acid systems." Atmospheric Chemistry and Physics Discussions 8, no. 5 (October 21, 2008): 18295–321. http://dx.doi.org/10.5194/acpd-8-18295-2008.
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Abstract. Binary heterogeneous nucleation of water-succinic/glutaric/malonic/adipic acid on nanometer-sized particles is investigated within the frame of classical heterogeneous nucleation theory. Homogeneous nucleation is also included for comparison. It is found that the nucleation probabilities depend on the contact angle and on the size of the seed particles. New thermodynamical properties, such as saturation vapor pressure, density and surface tension for all the dicarboxylic acid aqueous solutions are included in the calculations. While the new surface tension and density formulations do not bring any significant difference in the computed nucleation rate for homogeneous nucleation for succinic and glutaric acids, the use of the newly derived equations for the vapor pressure decrease the acid concentrations in gas phase with 3 orders of magnitude. According to our calculations, the binary heterogeneous nucleation of succinic acid-water and glutaric acid-water – although it requires a 3–4 orders of magnitude lower vapor concentrations than the homogeneous nucleation – cannot take place in atmospheric conditions. On the other hand binary homogeneous nucleation of adipic acid-water systems might be possible in conditions occuring in upper boundary layer. However, a more detailed characterization of the interaction between the surface and the molecules of the nucleating vapor should be considered in the future.
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Vejmelková, Eva, Monika Čáchová, Dana Koňáková, Pavel Reiterman, and Robert Černý. "Lime Plasters Containing Waste Ceramic Powder as Partial Replacement of Siliceous Aggregates." Advanced Materials Research 1035 (October 2014): 77–82. http://dx.doi.org/10.4028/www.scientific.net/amr.1035.77.
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Waste materials are utilized with an increasing frequency in the building industry, during the last decades. The motivation is both environmental and economical. In this paper, waste ceramic powder produced at the grinding of hollow brick blocks used in precise-walling technologies, is applied as a partial replacement of siliceous aggregates of lime plasters. The designed plaster mixes are analyzed from the point of view of their basic physical, mechanical, hygric and thermal properties. The bulk density, matrix density, open porosity, compressive strength, bending strength, water vapor diffusion permeability, water vapor diffusion coefficient, water vapor diffusion resistance factor, thermal conductivity and specific heat capacity are the investigated parameters. A reference lime plaster is analyzed as well, for the sake of comparison. Experimental results show a remarkable enhancement of mechanical properties of the plasters with the increasing dosage of ceramic powder. Moreover, the thermal insulation properties are improved and the water vapor diffusion capability of the plasters with ceramic powder increases.
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Kutikoff, Seth, Xiaomao Lin, Steven R. Evett, Prasanna Gowda, David Brauer, Jerry Moorhead, Gary Marek, et al. "Water vapor density and turbulent fluxes from three generations of infrared gas analyzers." Atmospheric Measurement Techniques 14, no. 2 (February 18, 2021): 1253–66. http://dx.doi.org/10.5194/amt-14-1253-2021.
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Abstract. Fast-response infrared gas analyzers (IRGAs) have been widely used over 3 decades in many ecosystems for long-term monitoring of water vapor fluxes in the surface layer of the atmosphere. While some of the early IRGA sensors are still used in these national and/or regional eco-flux networks, optically improved IRGA sensors are newly employed in the same networks. The purpose of this study was to evaluate the performance of water vapor density and flux data from three generations of IRGAs – LI-7500, LI-7500A, and LI-7500RS (LI-COR Bioscience, Inc., Nebraska, USA) – over the course of a growing season in Bushland, Texas, USA, in an irrigated maize canopy for 90 d. Water vapor density measurements were in generally good agreement, but temporal drift occurred in different directions and magnitudes. Means exhibited mostly shift changes that did not impact the flux magnitudes, while their variances of water vapor density fluctuations were occasionally in poor agreement, especially following rainfall events. LI-7500 cospectra were largest compared to LI-7500RS and LI-7500A, especially under unstable and neutral static stability. Agreement among the sensors was best under the typical irrigation-cooled boundary layer, with a 14 % interinstrument coefficient of variability under advective conditions. Generally, the smallest variances occurred with the LI-7500RS, and high-frequency spectral corrections were larger for these measurements, resulting in similar fluxes between the LI-7500A and LI-7500RS. Fluxes from the LI-7500 were best representative of growing season ET based on a world-class lysimeter reference measurement, but using the energy balance ratio as an estimate of systematic bias corrected most of the differences among measured fluxes.
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Sadeghpour, A., Z. Zeng, H. Ji, N. Dehdari Ebrahimi, A. L. Bertozzi, and Y. S. Ju. "Water vapor capturing using an array of traveling liquid beads for desalination and water treatment." Science Advances 5, no. 4 (April 2019): eaav7662. http://dx.doi.org/10.1126/sciadv.aav7662.
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Growing concern over the scarcity of freshwater motivates the development of compact and economic vapor capture methods for distributed thermal desalination or harvesting of water. We report a study of water vapor condensation on cold liquid beads traveling down a massive array of vertical cotton threads that act as pseudo-superhydrophilic surfaces. These liquid beads form through intrinsic flow instability and offer localized high-curvature surfaces that enhance vapor diffusion toward the liquid surface, a critical rate-limiting step. As the liquid flow rate increases, the bead spacing decreases, whereas the bead size and speed stay nearly constant. The resulting increase in the spatial bead density leads to mass transfer conductances and hence condensation rates per volume that are almost three times higher than the best reported values. Parallel and contiguous gas flow paths also result in a substantial reduction in gas pressure drop and hence electric fan power consumption.
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D’Angelo, M., S. Cazaux, I. Kamp, W. F. Thi, and P. Woitke. "Water delivery in the inner solar nebula." Astronomy & Astrophysics 622 (February 2019): A208. http://dx.doi.org/10.1051/0004-6361/201833715.
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Context. Endogenous or exogenous, dry or wet, various scenarios have been depicted for the origin of water on the rocky bodies in our solar system. Hydrated silicates found in meteorites and in interplanetary dust particles, together with observations of abundant water reservoirs in the habitable zone of protoplanetary disks, are evidence that support aqueous alteration of silicate dust grains by water vapor condensation in a nebular setting. Aims. We investigate the thermodynamics (temperature and pressure dependencies) and kinetics (adsorption rates and energies, surface diffusion and cluster formation) of water adsorption on surfaces of forsterite grains, constraining the location in the solar nebula where aqueous alteration of silicates by water vapor adsorption can occur efficiently and leads to the formation of phyllosilicates. We analyze the astrophysical conditions favorable for such hydration mechanism and the implications for water on solid bodies. Methods. The protoplanetary disk model (ProDiMo) code is tuned to simulate the thermochemical disk structure of the early solar nebula at three evolutionary stages. Pressure, temperature, and water vapor abundance within 1 au of the protosun were extracted and used as input for a Monte Carlo code to model water associative adsorption using adsorption energies that resemble the forsterite [1 0 0] crystal lattice. Results. Hydration of forsterite surfaces by water vapor adsorption could have occurred within the nebula lifetime already at a density of 108 cm−3, with increasing surface coverage for higher water vapor densities. Full surface coverage is attained for temperatures lower than 500 K, while for hotter grain surfaces water cluster formation plays a crucial role. Between 0.5 and 10 Earth oceans can arise from the agglomeration of hydrated 0.1 μm grains into an Earth-sized planet. However, if grain growth occurs dry and water vapor processes the grains afterward, this value can decrease by two orders of magnitude. Conclusions. This work shows that water cluster formation enhances the water surface coverage and enables a stable water layer to form at high temperature and low water vapor density conditions. Finally, surface diffusion of physisorbed water molecules shortens the timescale for reaching steady state, enabling phyllosilicate formation within the solar nebula timescale.
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Xia, Pengfei, Shirong Ye, Peng Jiang, Lin Pan, and Min Guo. "Assessing water vapor tomography in Hong Kong with improved vertical and horizontal constraints." Annales Geophysicae 36, no. 4 (July 9, 2018): 969–78. http://dx.doi.org/10.5194/angeo-36-969-2018.
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Abstract. In this study, we focused on the retrieval of atmospheric water vapor density by optimizing the tomography technique. First, we established a new atmospheric weighted average temperature model that considers the effects of temperature and height, assisted by Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) products. Next, we proposed a new method to determine the scale height of water vapor, which will improve the quality of vertical constraints. Finally, we determined the smoothing factor in the horizontal constraint based on Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) products. To evaluate the advantages of the optimized technique over the traditional method, we used GPS datasets collected in Hong Kong in August 2016 to estimate the vertical distribution of water vapor density using both methods. We further validated the tomography results from the optimized technique using radiosonde products. The results show that the water vapor density quality obtained by the optimized technique is 13.8 % better below 3.8 km and 8.1 % better above 3.8 km than that obtained by the traditional technique. We computed the success rate of the tomography technique based on the Pearson product-moment correlation coefficient (PCC) and root mean square (RMS). The success rate of the optimized topography technique was approximately 10 % higher than that of the traditional tomography method.
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Slusher, Joseph T., Peter T. Cummings, Yeqiong Hu, Carmen A. Vega, and John P. O'Connell. "Vapor-Liquid Equilibrium and Density Measurements of Alkylammonium Bromide + Propanol + Water Systems." Journal of Chemical & Engineering Data 40, no. 4 (July 1995): 792–98. http://dx.doi.org/10.1021/je00020a012.
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Remsing, Richard C., Erte Xi, Srivathsan Vembanur, Sumit Sharma, Pablo G. Debenedetti, Shekhar Garde, and Amish J. Patel. "Pathways to dewetting in hydrophobic confinement." Proceedings of the National Academy of Sciences 112, no. 27 (June 22, 2015): 8181–86. http://dx.doi.org/10.1073/pnas.1503302112.
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Liquid water can become metastable with respect to its vapor in hydrophobic confinement. The resulting dewetting transitions are often impeded by large kinetic barriers. According to macroscopic theory, such barriers arise from the free energy required to nucleate a critical vapor tube that spans the region between two hydrophobic surfaces—tubes with smaller radii collapse, whereas larger ones grow to dry the entire confined region. Using extensive molecular simulations of water between two nanoscopic hydrophobic surfaces, in conjunction with advanced sampling techniques, here we show that for intersurface separations that thermodynamically favor dewetting, the barrier to dewetting does not correspond to the formation of a (classical) critical vapor tube. Instead, it corresponds to an abrupt transition from an isolated cavity adjacent to one of the confining surfaces to a gap-spanning vapor tube that is already larger than the critical vapor tube anticipated by macroscopic theory. Correspondingly, the barrier to dewetting is also smaller than the classical expectation. We show that the peculiar nature of water density fluctuations adjacent to extended hydrophobic surfaces—namely, the enhanced likelihood of observing low-density fluctuations relative to Gaussian statistics—facilitates this nonclassical behavior. By stabilizing isolated cavities relative to vapor tubes, enhanced water density fluctuations thus stabilize novel pathways, which circumvent the classical barriers and offer diminished resistance to dewetting. Our results thus suggest a key role for fluctuations in speeding up the kinetics of numerous phenomena ranging from Cassie–Wenzel transitions on superhydrophobic surfaces, to hydrophobically driven biomolecular folding and assembly.
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Boylan, P., D. Helmig, and J. H. Park. "Characterization and mitigation of water vapor effects in the measurement of ozone by chemiluminescence with nitric oxide." Atmospheric Measurement Techniques 7, no. 5 (May 13, 2014): 1231–44. http://dx.doi.org/10.5194/amt-7-1231-2014.
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Abstract. Laboratory experiments were conducted to investigate the effects of water vapor on the reaction of nitric oxide with ozone in a gas-phase chemiluminescence instrument used for fast response and high sensitivity detection of atmospheric ozone. Water vapor was introduced into a constant level ozone standard and both ozone and water vapor signals were recorded at 10 Hz. The presence of water vapor was found to reduce, i.e. quench, the ozone signal. A dimensionless correction factor was determined to be 4.15 ± 0.14 × 10−3, which corresponds to a 4.15% increase in the corrected ozone signal per 10 mmol mol−1 of co-sampled water vapor. An ozone-inert water vapor permeable membrane (a Nafion dryer with a counterflow of dry air from a compressed gas cylinder) was installed in the sampling line and was shown to remove the bulk of the water vapor in the sample air. At water vapor mole fractions above 25 mmol mol−1, the Nafion dryer removed over 75% of the water vapor in the sample. This reduced the required ozone signal correction from over 11% to less than 2.5%. The Nafion dryer was highly effective at reducing the fast fluctuations of the water vapor signal (more than 97%) while leaving the ozone signal unaffected, which is a crucial improvement for minimizing the quenching interference of water vapor fluxes and required density correction in the determination of ozone fluxes by the eddy covariance technique.
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Imaki, Masaharu, Ryota Kojima, and Shumpei Kameyama. "Development of wavelength locking circuit for 1.53 micron water vapor monitoring coherent differential absorption LIDAR." EPJ Web of Conferences 176 (2018): 05039. http://dx.doi.org/10.1051/epjconf/201817605039.
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We have studied a ground based coherent differential absorption LIDAR (DIAL) for vertical profiling of water vapor density using a 1.5μm laser wavelength. A coherent LIDAR has an advantage in daytime measurement compared with incoherent LIDAR because the influence of background light is greatly suppressed. In addition, the LIDAR can simultaneously measure wind speed and water vapor density. We had developed a wavelength locking circuit using the phase modulation technique and offset locking technique, and wavelength stabilities of 0.123 pm which corresponds to 16 MHz are realized. In this paper, we report the wavelength locking circuits for the 1.5 um wavelength.
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Yang, Fei, Jiming Guo, Junbo Shi, Lv Zhou, Yi Xu, and Ming Chen. "A Method to Improve the Distribution of Observations in GNSS Water Vapor Tomography." Sensors 18, no. 8 (August 2, 2018): 2526. http://dx.doi.org/10.3390/s18082526.
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Water vapor is an important driving factor in the related weather processes in the troposphere, and its temporal-spatial distribution and change are crucial to the formation of cloud and rainfall. Global Navigation Satellite System (GNSS) water vapor tomography, which can reconstruct the water vapor distribution using GNSS observation data, plays an increasingly important role in GNSS meteorology. In this paper, a method to improve the distribution of observations in GNSS water vapor tomography is proposed to overcome the problem of the relatively concentrated distribution of observations, enable satellite signal rays to penetrate more tomographic voxels, and improve the issue of overabundance of zero elements in a tomographic matrix. Numerical results indicate that the accuracy of the water vapor tomography is improved by the proposed method when the slant water vapor calculated by GAMIT is used as a reference. Comparative results of precipitable water vapor (PWV) and water vapor density (WVD) profiles from radiosonde station data indicate that the proposed method is superior to the conventional method in terms of the mean absolute error (MAE), standard deviations (STD), and root-mean-square error (RMS). Further discussion shows that the ill-condition of tomographic equation and the richness of data in the tomographic model need to be discussed separately.
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Yao, Yibin, Linyang Xin, and Qingzhi Zhao. "An improved pixel-based water vapor tomography model." Annales Geophysicae 37, no. 1 (February 1, 2019): 89–100. http://dx.doi.org/10.5194/angeo-37-89-2019.
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Abstract. As an innovative use of Global Navigation Satellite System (GNSS), the GNSS water vapor tomography technique shows great potential in monitoring three-dimensional water vapor variation. Most of the previous studies employ the pixel-based method, i.e., dividing the troposphere space into finite voxels and considering water vapor in each voxel as constant. However, this method cannot reflect the variations in voxels and breaks the continuity of the troposphere. Moreover, in the pixel-based method, each voxel needs a parameter to represent the water vapor density, which means that huge numbers of parameters are needed to represent the water vapor field when the interested area is large and/or the expected resolution is high. In order to overcome the abovementioned problems, in this study, we propose an improved pixel-based water vapor tomography model, which uses layered optimal polynomial functions obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) by adaptive training for water vapor retrieval. Tomography experiments were carried out using the GNSS data collected from the Hong Kong Satellite Positioning Reference Station Network (SatRef) from 25 March to 25 April 2014 under different scenarios. The tomographic results are compared to the ECMWF data and validated by the radiosonde. Results show that the new model outperforms the traditional one by reducing the root-mean-square error (RMSE), and this improvement is more pronounced, at 5.88 % in voxels without the penetration of GNSS rays. The improved model also has advantages in more convenient expression.
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Yang, Fei, Jiming Guo, Junbo Shi, Yinzhi Zhao, Lv Zhou, and Shengdeng Song. "A New Method of GPS Water Vapor Tomography for Maximizing the Use of Signal Rays." Applied Sciences 9, no. 7 (April 6, 2019): 1446. http://dx.doi.org/10.3390/app9071446.
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The spatio-temporal distribution of atmospheric water vapor information can be obtained by global positioning system (GPS) water vapor tomography. GPS signal rays pass through the tomographic area from different boundaries because the scope of the research region (latitude, longitude, and altitude) is designated in the process of tomographic modeling, the influence of the geographic distribution of receivers, and the geometric location of satellite constellations. Traditionally, only signal rays penetrating the entire tomographic area are considered in the computation of water vapor information, whereas those passing through the sides are neglected. Therefore, the accuracy of the tomographic result, especially at the bottom of the area, does not reach its full potential. To solve this problem, this paper proposes a new method that simultaneously considers the discretized tomographic voxels and the troposphere outside the research area as unknown parameters. This method can effectively improve the utilization of existing GPS observations and increase the number of voxels crossed by satellite signals, especially by increasing the proportion of voxels penetrated. A tomographic experiment is implemented using GPS data from the Hong Kong Satellite Positioning Reference Station Network. Compared to the traditional method, the proposed method increases the number of voxels crossed by signal rays and the utilization of the observed data by 15.14% and 19.68% on average, respectively. Numerical results, including comparisons of slant water vapor (SWV), precipitable water vapor (PWV), and water vapor density profile, show that the proposed method is better than traditional methods. In comparison to the water vapor density profile, the root-mean-square error (RMS), mean absolute error (MAE), standard deviation (SD), and bias of the proposed method are 1.39, 1.07, 1.30, and −0.21 gm−3, respectively. For the SWV and PWV comparison, the RMS/MAE of the proposed method are 10.46/8.17 mm and 4.00/3.39 mm, respectively.
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Abbasi, Sadaf Aftab, Arzu Marmaralı, and Gözde Ertekin. "Thermal comfort properties of weft knitted quilted fabrics." International Journal of Clothing Science and Technology 32, no. 6 (May 4, 2020): 837–47. http://dx.doi.org/10.1108/ijcst-07-2019-0111.
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PurposeThis paper investigates the thermal comfort properties of quilted (jersey cord) fabrics produced with different width of diamond pattern, different filling yarn linear density and different types of material.Design/methodology/approachA total of 12 fabrics were knitted by varying the width of diamond pattern (1 and 3 cm), the filling yarn linear density (300 and 900 denier) and the type of materials (cotton, polyester and their combination). In this regard, air permeability, thermal conductivity, thermal resistance, thermal absorptivity and relative water vapor permeability of these fabrics were measured and evaluated statistically.FindingsThe results showed that fabrics knitted using cotton yarn in both front and back surfaces exhibit higher thermal conductivity, thermal absorptivity and relative water vapor permeability characteristics; whereas samples knitted using polyester yarn in both surfaces have higher air permeability and thermal resistance. As the linear density of filling yarn increases, thickness and thermal resistance of the samples increase and air permeability, thermal conductivity, water vapor permeability characteristics decrease. When the effect of the width of diamond pattern compared, it is seen that an increase in the width of pattern lead to an increase in thickness and thermal resistance and a decrease in thermal conductivity, thermal absorptivity and water vapor permeability values.Originality/valueMany researches were carried out on the thermal comfort properties of knitted fabrics, however there is a lack of research efforts regarding thermal comfort properties of quilted fabrics.
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Lill, A. "Water-Vapor Conductance and Shell Characteristics of Superb Lyrebird Eggs." Australian Journal of Zoology 35, no. 6 (1987): 553. http://dx.doi.org/10.1071/zo9870553.
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Superb lyrebirds exhibit a suite of breeding characteristics (a long incubation period, low incubation constancy, use of an enclosed nest, and winter nesting) which might cause an unusual pattern of gas exchange in the egg during incubation. This possibility was investigated by determining the egg's natural rate of water loss during incubation and its water vapour conductance, and by measuring shell parameters which influence these properties. The estimated fractional weight loss of the 61,5-g egg during incubation was 16%. This was similar to that in other species, as was the calculated water vapour pressure difference across the shell (27 Torr=3.6 kPa). The mean rate of water loss (194 mg day-') and the mean water vapour conductance (7.08 mg day-' Torr-' =53.23 mg day-' kPa-') of the egg were, however, relatively low. True shell thickness averaged 218 �m and pore density was 50-56 pores per square centimetre. Pores were unbranched and relatively evenly distributed. The fairly standard fractional weight loss over the 50-day incubation period resulted from the egg's low water vapour conductance which, in turn, stemmed mainly from a comparatively low pore density. It was concluded that the protracted incubation period, resulting from the low incubation constancy at low ambient temperatures, was probably the principal influence on the evolution of the small pore area and low water vapour conductance of the lyrebird egg.
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Zavershinskii, I. P., and D. P. Porfirev. "NUMERICAL SIMULATION OF THE SWIRLED FLOW OF WATER STEAM PLASMA WITH ALUMINUM MICROPARTICLES." Journal of Dynamics and Vibroacoustics 6, no. 4 (May 16, 2021): 25–34. http://dx.doi.org/10.18287/2409-4579-2020-6-4-25-34.
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A study of the discharge plasma with a vortex flow of an argon + water vapor mixture with aluminum particles in a tube of a plasma vortex reactor (PVR) was carried out. The parameters of the discharge, plasma, and working flow in the PVR have been measured. Spectral methods were used to estimate the electron temperature, rotational and vibrational temperatures of excited molecular complexes, the temperature of metal clusters, and the electron density of plasma. A kinetic scheme is proposed for calculating the operating modes in a reactor using a water vapor discharge with aluminum particles. Numerical simulation of a vortex flow of pure water vapor with aluminum particles in the presence of a heating source is carried out.
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Fasci, Eugenio, Hemanth Dinesan, Luigi Moretti, Andrea Merlone, Antonio Castrillo, and Livio Gianfrani. "Dual-laser frequency-stabilized cavity ring-down spectroscopy for water vapor density measurements." Metrologia 55, no. 5 (July 27, 2018): 662–69. http://dx.doi.org/10.1088/1681-7575/aad15e.
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Gilbert, William J. R., Javid Safarov, David L. Minnick, M. Alejandra Rocha, Egon P. Hassel, and Mark B. Shiflett. "Density, Viscosity, and Vapor Pressure Measurements of Water + Lithium Bis(trifluoromethylsulfonyl)imide Solutions." Journal of Chemical & Engineering Data 62, no. 7 (June 5, 2017): 2056–66. http://dx.doi.org/10.1021/acs.jced.7b00135.
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Yang, Zong-Quan, Yong-Zhong Wang, Zhong-Run Li, Cheng Zhang, Ling Hua, De-Chang Zeng, Gui-Wen Qiao, A. Ulyashin, and I. Gorolchuk. "The Enhancement in Critical Current Density of YBa2Cu3O7−y by Water Vapor Treatment." Physica Status Solidi (a) 155, no. 2 (June 16, 1996): 473–77. http://dx.doi.org/10.1002/pssa.2211550221.
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Ruf, Christopher S., and Calvin T. Swift. "Atmospheric Profiling of Water Vapor Density with a 20.5–23.5 GHz Autocorrelation Radiometer." Journal of Atmospheric and Oceanic Technology 5, no. 4 (August 1988): 539–46. http://dx.doi.org/10.1175/1520-0426(1988)005<0539:apowvd>2.0.co;2.
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Ilek, Anna, Courtney M. Siegert, and Adam Wade. "Hygroscopic contributions to bark water storage and controls exerted by internal bark structure over water vapor absorption." Trees 35, no. 3 (January 24, 2021): 831–43. http://dx.doi.org/10.1007/s00468-021-02084-0.
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Abstract Key message Hygroscopicity is a crucial element of bark water storage and can reach >60% of water holding capacity of bark depending on tree species Abstract Bark forms the outer layer of woody plants, and it is directly exposed to wetting during rainfall and reacts to changes in relative humidity, i.e., it may exchange water with the atmosphere through absorption and desorption of water vapor. A current paradigm of bark hydrology suggests that the maximum water storage of bark empties between precipitation events and is principally controlled by bark thickness and roughness. We hypothesize that (1) the ability of bark to absorb water vapor during non-rainfall periods (i.e., hygroscopicity) leads to partial saturation of bark tissues during dry periods that may alter the rate of bark saturation during rainfall, and (2) the degree of bark saturation through hygroscopic water is a function of internal bark structure, including porosity and density, that varies among species. To address these questions, we conducted laboratory experiments to measure interspecific differences in bark physical structure as it relates to water storage mechanisms among common tree species (hickory (Carya spp.), oak (Quercus spp.), sweetgum (Liquidambar styraciflua), and loblolly pine (Pinus taeda)) in the southeastern United States. Furthermore, we considered how these properties changed across total bark, outer bark, and inner bark. We found a distinct difference between hickory and oak, whereby hickory had 5.6% lower specific density, 31.1% higher bulk density, and 22.4% lower total porosity of outer bark resulting in higher hygroscopicity compared to oaks. For all species, hygroscopicity increased linearly with bulk density (R2 = 0.65–0.81) and decreased linearly with total porosity (R2 = 0.64–0.88). Overall, bark hygroscopicity may constitute an average of 30% of total bark water storage capacity. Therefore, in humid climates like those of the southeastern USA, the proportion of bark that remains saturated during non-storm conditions should not be considered negligible.
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Xu, Wen Jing, and Hong Yan Liu. "Ground-Based Microwave Radiometer Profiler Observations before a Heavy Rainfall." Applied Mechanics and Materials 137 (October 2011): 312–15. http://dx.doi.org/10.4028/www.scientific.net/amm.137.312.
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Ground-based 12-channel microwave radiometer profiler TP/WVP-3000 can provide temperature and vapor density profile per minute up to 10 km height. The observations feature apparent change before heavy rainfall obtained by TP/WVP-3000 is presented in this paper. It demonstrates the detailed thermodynamic features that the atmosphere becomes colder and drier above height 3-4 km about 9 hours before the rain, the integrated water vapor gradually increases from 5 cm to 9 cm, the integrated cloud water change from near zero to 15 mm and the vapor density also increases rapidly about half an hour before the rain, which can be concluded that the radiometer profiler is able to improve the understanding of mesoscale weather in this case due to the profiler significantly improves the temporal resolution of atmospheric thermodynamic observations.
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Xia, P., C. Cai, and Z. Liu. "GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles." Annales Geophysicae 31, no. 10 (October 24, 2013): 1805–15. http://dx.doi.org/10.5194/angeo-31-1805-2013.
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Abstract. Traditionally, balloon-based radiosonde soundings are used to study the spatial distribution of atmospheric water vapour. However, this approach cannot be frequently employed due to its high cost. In contrast, GPS tomography technique can obtain water vapour in a high temporal resolution. In the tomography technique, an iterative or non-iterative reconstruction algorithm is usually utilised to overcome rank deficiency of observation equations for water vapour inversion. However, the single iterative or non-iterative reconstruction algorithm has their limitations. For instance, the iterative reconstruction algorithm requires accurate initial values of water vapour while the non-iterative reconstruction algorithm needs proper constraint conditions. To overcome these drawbacks, we present a combined iterative and non-iterative reconstruction approach for the three-dimensional (3-D) water vapour inversion using GPS observations and COSMIC profiles. In this approach, the non-iterative reconstruction algorithm is first used to estimate water vapour density based on a priori water vapour information derived from COSMIC radio occultation data. The estimates are then employed as initial values in the iterative reconstruction algorithm. The largest advantage of this approach is that precise initial values of water vapour density that are essential in the iterative reconstruction algorithm can be obtained. This combined reconstruction algorithm (CRA) is evaluated using 10-day GPS observations in Hong Kong and COSMIC profiles. The test results indicate that the water vapor accuracy from CRA is 16 and 14% higher than that of iterative and non-iterative reconstruction approaches, respectively. In addition, the tomography results obtained from the CRA are further validated using radiosonde data. Results indicate that water vapour densities derived from the CRA agree with radiosonde results very well at altitudes above 2.5 km. The average RMS value of their differences above 2.5 km is 0.44 g m−3.
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Peters, Ole, J. David Neelin, and Stephen W. Nesbitt. "Mesoscale Convective Systems and Critical Clusters." Journal of the Atmospheric Sciences 66, no. 9 (September 1, 2009): 2913–24. http://dx.doi.org/10.1175/2008jas2761.1.
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Abstract Size distributions and other geometric properties of mesoscale convective systems (MCSs), identified as clusters of adjacent pixels exceeding a precipitation threshold in satellite radar images, are examined with respect to a recently identified critical range of water vapor. Satellite microwave estimates of column water vapor and precipitation show that the onset of convection and precipitation in the tropics can be described as a phase transition, where the rain rate and likelihood of rainfall suddenly increase as a function of water vapor. This is confirmed in Tropical Rainfall Measuring Mission radar data used here. Percolation theory suggests that cluster properties should be highly sensitive to changes in the density of occupied pixels, which here translates into a rainfall probability, which in turn sensitively depends on the water vapor. To confirm this, clusters are categorized by their prevalent water vapor. As expected, mean cluster size and radius of gyration strongly increase as the critical water vapor is approached from below. In the critical region one finds scale-free size distributions spanning several orders of magnitude. Large clusters are typically from the critical region: at low water vapor most clusters are small, and supercritical water vapor values are too rare to contribute much. The perimeter of the clusters confirms previous observations in satellite, field, and model data of robust nontrivial scaling. The well-known area–perimeter scaling is fully compatible with the quantitative prediction from the plausible null model of gradient percolation, where the accessible hull is a fractal object with dimension 4/3.
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Livingston, J. M., B. Schmid, P. B. Russell, J. R. Podolske, J. Redemann, and G. S. Diskin. "Comparison of Water Vapor Measurements by Airborne Sun Photometer and Diode Laser Hygrometer on the NASA DC-8." Journal of Atmospheric and Oceanic Technology 25, no. 10 (October 1, 2008): 1733–43. http://dx.doi.org/10.1175/2008jtecha1047.1.
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Abstract In January–February 2003, the 14-channel NASA Ames airborne tracking sun photometer (AATS) and the NASA Langley/Ames diode laser hygrometer (DLH) were flown on the NASA DC-8 aircraft. The AATS measured column water vapor on the aircraft-to-sun path, while the DLH measured local water vapor in the free stream between the aircraft fuselage and an outboard engine cowling. The AATS and DLH measurements have been compared for two DC-8 vertical profiles by differentiating the AATS column measurement and/or integrating the DLH local measurement over the altitude range of each profile (7.7–10 km and 1.1–12.5 km). These comparisons extend, for the first time, tests of AATS water vapor retrievals to altitudes >∼6 km and column contents <0.1 g cm−2. To the authors’ knowledge, this is the first time suborbital spectroscopic water vapor measurements using the 940-nm band have been tested in conditions so high and dry. Values of layer water vapor (LWV) calculated from the AATS and DLH measurements are highly correlated for each profile. The composite dataset yields r 2 0.998, rms difference 7.7%, and bias (AATS minus DLH) 1.0%. For water vapor densities AATS and DLH had r 2 0.968, rms difference 27.6%, and bias (AATS minus DLH) −4.2%. These results for water vapor density compare favorably with previous comparisons of AATS water vapor to in situ results for altitudes <∼6 km, columns ∼0.1 to 5 g cm−2, and densities ∼0.1 to 17 g m−3.
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Chen, Yi, Thuy Hang Nguyen, Shao Lin Zhang, Z. Zhang, Hongyan Yue, Jiawen Jian, and Woo-Chul Yang. "Study on the detection behavior of defect-rich single-walled carbon nanotubes toward perchlorate." Functional Materials Letters 11, no. 02 (April 2018): 1850032. http://dx.doi.org/10.1142/s1793604718500327.
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Defect-rich single-walled carbon nanotubes (SWCNTs) were prepared by a water vapor flow-assisted chemical vapor deposition process. The correlation between defect density and water flow was quantitively studied using Raman spectrum. The detection capabilities of defective SWCNTs films toward perchlorate anions were investigated. It was found the defect-rich SWCNTs could adsorb more perchlorate anions owing to the strong chemical bonding between anions and defective sites. However, the detective response of defective SWCNTs toward perchlorate was not in compliance with anion adsorption. A tradeoff phenomenon between response and adsorption was found as the defect density of SWCNTs increased. This work is expected to provide a guidance to the future design of SWCNTs based ion detector.
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Vejmelková, Eva, Petr Máca, Petr Konvalinka, and Robert Černý. "Innovative Lime-Pozzolana Renders for Reconstruction of Historical Buildings." Advanced Materials Research 324 (August 2011): 372–75. http://dx.doi.org/10.4028/www.scientific.net/amr.324.372.
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Bulk density, matrix density, open porosity, compressive strength, bending strength, water sorptivity, moisture diffusivity, water vapor diffusion coefficient, thermal conductivity, specific heat capacity and thermal diffusivity of two innovative renovation renders on limepozzolana basis are analyzed. The obtained results are compared with reference lime plaster and two commercial renovation renders, and conclusions on the applicability of the particular renders in practical reconstruction works are drawn.
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Wagner, T., S. Beirle, H. Sihler, and K. Mies. "A feasibility study for the retrieval of the total column precipitable water vapor from satellite observations in the blue spectral range." Atmospheric Measurement Techniques Discussions 6, no. 2 (April 12, 2013): 3643–74. http://dx.doi.org/10.5194/amtd-6-3643-2013.
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Abstract. We present a new algorithm for satellite retrievals of the atmospheric water vapor column in the blue spectral range. The water vapor absorption cross section in the blue spectral range is much weaker than in the red spectral range. Thus the detection limit and the uncertainty of individual observations is systematically larger than for retrievals at longer wavelengths. Nevertheless, water vapor retrievals in the blue spectral range have also several advantages: since the surface albedo in the blue spectral range is similar over land and ocean, water vapor retrievals are more consistent than for longer wavelengths. Compared to retrievals at longer wavelengths, over ocean the sensitivity for atmospheric layers close to the surface is higher due to the (typically 2 to 3 times) higher ocean albedo in the blue. Water vapor retrievals in the blue spectral range are also possible for satellite sensors, which do not measure at longer wavelengths of the visible spectral range like the Ozone Monitoring instrument (OMI). We investigated details of the water vapor retrieval in the blue spectral range based on radiative transfer simulations and observations from the Global Ozone Monitoring Experiment 2 (GOME-2) and OMI. It is demonstrated that it is possible to retrieve the atmospheric water vapor column density in the blue spectral range over most parts of the globe. The findings of our study are of importance also for future satellite missions like e.g. Sentinel 4 and 5.
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Fourteau, Kévin, Florent Domine, and Pascal Hagenmuller. "Impact of water vapor diffusion and latent heat on the effective thermal conductivity of snow." Cryosphere 15, no. 6 (June 18, 2021): 2739–55. http://dx.doi.org/10.5194/tc-15-2739-2021.
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Abstract. Heat transport in snowpacks is understood to occur through the two processes of heat conduction and latent heat transport carried by water vapor, which are generally treated as decoupled from one another. This paper investigates the coupling between both these processes in snow, with an emphasis on the impacts of the kinetics of the sublimation and deposition of water vapor onto ice. In the case when kinetics is fast, latent heat exchanges at ice surfaces modify their temperature and therefore the thermal gradient within ice crystals and the heat conduction through the entire microstructure. Furthermore, in this case, the effective thermal conductivity of snow can be expressed by a purely conductive term complemented by a term directly proportional to the effective diffusion coefficient of water vapor in snow, which illustrates the inextricable coupling between heat conduction and water vapor transport. Numerical simulations on measured three-dimensional snow microstructures reveal that the effective thermal conductivity of snow can be significantly larger, by up to about 50 % for low-density snow, than if water vapor transport is neglected. A comparison of our numerical simulations with literature data suggests that the fast kinetics hypothesis could be a reasonable assumption for modeling heat and mass transport in snow. Lastly, we demonstrate that under the fast kinetics hypothesis the effective diffusion coefficient of water vapor is related to the effective thermal conductivity by a simple linear relationship. Under such a condition, the effective diffusion coefficient of water vapor is expected to lie in the narrow 100 % to about 80 % range of the value of the diffusion coefficient of water vapor in air for most seasonal snows. This may greatly facilitate the parameterization of water vapor diffusion of snow in models.
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Sokratov, Sergey A., and Norikazu Maeno. "Wavy temperature and density distributions formed in snow." Annals of Glaciology 26 (1998): 73–76. http://dx.doi.org/10.1017/s0260305500014592.
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Precise measurements of temperature and density distributions in snow under an applied temperature gradient showed that alternation of evaporation and condensation zones is formed and causes the wavy patterns in quasi-steady temperature and density distributions. In samples with a snow density of 200–500 kg2m−3the wavelength was 3–7 cm and the amplitude was roughly 2°C. The present result gives a clue to explaining the wide range of previously measured water-vapor diffusion coefficients in snow.
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Dai, Guangyao, Dietrich Althausen, Julian Hofer, Ronny Engelmann, Patric Seifert, Johannes Bühl, Rodanthi-Elisavet Mamouri, Songhua Wu, and Albert Ansmann. "Calibration of Raman lidar water vapor profiles by means of AERONET photometer observations and GDAS meteorological data." Atmospheric Measurement Techniques 11, no. 5 (May 8, 2018): 2735–48. http://dx.doi.org/10.5194/amt-11-2735-2018.
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Abstract. We present a practical method to continuously calibrate Raman lidar observations of water vapor mixing ratio profiles. The water vapor profile measured with the multiwavelength polarization Raman lidar PollyXT is calibrated by means of co-located AErosol RObotic NETwork (AERONET) sun photometer observations and Global Data Assimilation System (GDAS) temperature and pressure profiles. This method is applied to lidar observations conducted during the Cyprus Cloud Aerosol and Rain Experiment (CyCARE) in Limassol, Cyprus. We use the GDAS temperature and pressure profiles to retrieve the water vapor density. In the next step, the precipitable water vapor from the lidar observations is used for the calibration of the lidar measurements with the sun photometer measurements. The retrieved calibrated water vapor mixing ratio from the lidar measurements has a relative uncertainty of 11 % in which the error is mainly caused by the error of the sun photometer measurements. During CyCARE, nine measurement cases with cloud-free and stable meteorological conditions are selected to calculate the precipitable water vapor from the lidar and the sun photometer observations. The ratio of these two precipitable water vapor values yields the water vapor calibration constant. The calibration constant for the PollyXT Raman lidar is 6.56 g kg−1 ± 0.72 g kg−1 (with a statistical uncertainty of 0.08 g kg−1 and an instrumental uncertainty of 0.72 g kg−1). To check the quality of the water vapor calibration, the water vapor mixing ratio profiles from the simultaneous nighttime observations with Raman lidar and Vaisala radiosonde sounding are compared. The correlation of the water vapor mixing ratios from these two instruments is determined by using all of the 19 simultaneous nighttime measurements during CyCARE. Excellent agreement with the slope of 1.01 and the R2 of 0.99 is found. One example is presented to demonstrate the full potential of a well-calibrated Raman lidar. The relative humidity profiles from lidar, GDAS (simulation) and radiosonde are compared, too. It is found that the combination of water vapor mixing ratio and GDAS temperature profiles allow us to derive relative humidity profiles with the relative uncertainty of 10–20 %.
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JAWAD, NAEEM, ADNAN MAZARI, AKCAGUN ENGIN, HAVELKA ANTONIN, and KUS ZDENEK. "Analysis of thermal properties, water vapor resistance and radiant heat transmission through different combinations of firefighter protective clothing." Industria Textila 69, no. 06 (January 1, 2019): 458–65. http://dx.doi.org/10.35530/it.069.06.1463.
Full textAbstract:
This experimental work is an effort to seek the possibility of improvement in thermal protective performance of firefighter protective clothing at different levels of heat flux density. Improvement in thermal protective performance means enhancement in the time of exposure against the heat flux, which will provide extra time to firefighters to perform their duties without suffering from severe injuries. Four different multilayer combinations of firefighter protective clothing were investigated. Each combination consists of outer shell, moisture barrier and thermal liner. Aerogel sheet was also employed as a substitute to thermal barrier. Initially, properties like thermal resistance, thermal conductivity, and water vapor resistance of multilayer fabric assemblies were investigated. Later on these combinations were exposed to different levels of radiant heat flux density i.e. at 10, 20 and 30 kW/m2 as per ISO 6942 standard. It was noted that those combinations in which aerogel blanket was used as thermal barrier acquire greater thermal resistance, water vapor resistance and have less transmitted heat flux density values.