Search

Solar power is a demand of our planet in coming days due to the depletion of non-renewable sources of energy. The renewable sources of energy are responsible for 80 % of world’s power and we all are directly dependent on non-renewable source which will only last in coming decades. Due to increase in power demands new development in renewable sources of energy are going on due to which on commercial level solar cell achieved an efficiency of 15 – 20 % and improving day by day. At a panel inclination of 22 oC, the effect of panel temperature and relative humidity on photovoltaic are studied. A precision digital hygrometer and thermometer, and a digital clamp meter were used in the process. Results obtained show that the effect of relative humidity on current, voltage, power of single and 10 panels combined together. The results also show that voltage and current remain fairly stable between 15 % to 35 % relative humidity. Panel’s temperature also plays a significant role on performance after 55 ºC, the voltage started dropping in both cases. Output from the wind turbine has also been measured on a working condition day, and different readings have been recorded with an interval of 15 mins at different wind speeds. It works by converting the kinetic energy in the wind first into rotational kinetic energy in the turbine and then electrical energy that can be supplied. The output energy comes directly depend on speed of wind and the blades swept area. Renewable Energy Hybrid System (REHS) is a system that utilizes two sources or more of renewable energy. As an advantage, it will produce continuous source of energy and utilizing one source in the absence of other source(s). The aim of this study is to enhance the energy output of renewable energy system which is the wind turbine by incorporating solar panels. [ABSTRACT FROM AUTHOR]

Measuring the relative humidity of air is an important challenge for meteorological measurements, food conservation, building design, and evaporation control, among other applications. Relative humidity can be measured with a psychrometer, which is a hygrometer composed of two identical thermometers. The bulb of one thermometer is covered by a wick soaked with water so that evaporative cooling makes it indicate a lower temperature than the dry-bulb thermometer; it is possible to determine the relative humidity from the difference between these readings. We describe both a model and an experimental setup to illustrate the principle of a psychrometer for a pedagogical laboratory. The science of psychrometry could be more broadly taught at the undergraduate level to help introduce students to aspects of measurement techniques, fluid mechanics, heat transfer, and non-equilibrium thermodynamics. [ABSTRACT FROM AUTHOR]

This study aimed to obtain reference dosimetry practices for flattened photon and electron beams. A questionnaire survey on these practices was sent to 37 facilities that performed radiotherapy using these beams in Fukui, Ishikawa, Niigata and Toyama, Japan. The survey comprised equipment (dosemeters, water phantoms, thermometers, barometers and hygrometers) and procedures for reference dosimetry (water used as the phantoms, verification of chamber placement, periodic checks of ion recombination- and polarity-corrections, pre-irradiation and relative humidity monitoring). Responses were received from 19 institutions. In the 19 institutions, a reference-class dosemeter was used for the reference dosimetry. In 6 of the 19 institutions, a 10-year-old or older dosemeter was used. Any barometers, thermometers and hygrometers were not recalibrated. Dosimetry equipment necessitates regular maintenance. Moreover, it is necessary to have a backup dosimetry system in clinics to account for potential malfunctions or instances when the primary system is sent for calibration. [ABSTRACT FROM AUTHOR]

The mid-infrared lightweight stratospheric hygrometer, "Pico-Light H2O", the successor of Pico-SDLA H2O, is presented and its performances are evaluated during the AsA 2022 balloon-borne intercomparison campaign conducted at CNES Aire-sur-l'Adour (AsA) balloon launch facility and the Aeroclub d'Aire-sur-l'Adour. The Pico-Light instrument primarily been developed for sounding of the upper troposphere and stratosphere. Though, during the AsA 2022 campaign we expand the range of comparison including the lower troposphere additionally. Three different types of hygrometers and two models of radiosonde were flown, operated by the French Space Agency (CNES) and the NOAA Global Monitoring Laboratory (GML) scientific teams: Pico-Light H2O, the NOAA Frost Point Hygrometer (FPH), the micro hygrometer (in an early phase of development), M20 and iMet-4 sondes. In this frame, we intend to validate measurements of Pico-Light H2O through a first intercomparison with the NOAA FPH instrument. The in situ monitoring of water vapour in the UT-LS keeps being very challenging from an instrumental point of view because of the very small amounts of water vapour to be measured in these regions of the atmosphere. Between the lapse rate tropopause (11 to 12.3 km) and 20 km, the mean relative difference between water vapour mixing ratio measurements by Pico-Light H2O and NOAA FPH was (4.2 ± 7.7) %, mean tropospheric difference is was (3.84 ± 23.64)%, with differences depending on the altitude range considered. In the troposphere, relative humidity over water (RH) comparisons leads to an agreement between both Pico-Light and NOAA FPH of -0.2% on average, with excursions of about 30% RH due to moisture variability. Expanding the comparison to meteorological sondes, the iMet-4 sondes agree well with both Pico-Light and FPH between ground and 7.5 km (within ± 3% RH) and so does for M20 sondes, up to 13 km, which are wet biased by 3% RH and dry biased by 20% in case of saturation. [ABSTRACT FROM AUTHOR]

The quantities that are usually measured are time, pressure, temperature, and relative humidity to mention but a few. The word humidity is used when we are dealing with water vapor which is a gas. The instrument used to measure the humidity is the hygrometer that can be based on electronics, optics, mechanics, chemicals, and others. The measurement of humidity shows its importance in applications such as food processing, meteorological, semiconductor, building and construction, medical, and automotive to mention but a few. This paper shows the adaptation of an optical interferometer, the Fabry-Perot (F-P), to measure the relative humidity. The transductors that have been probed are gelatin-thin films that are inserted between the mirrors of the FP. When water molecules are absorbed (desorbed) by the gelatin film, its refractive index and thickness change giving a movement of the rings in the interference pattern. The calibration plot comprises the ring displacement as a function of the relative humidity. [ABSTRACT FROM AUTHOR]

Climate change causes extreme heat and high humidity in some regions. The wet-bulb temperature (Tw) is a heat stress index, and the threshold is 35 °C. It is difficult to measure the value of Tw using a psychrometer, but the Tw value can be calculated using the air temperature and humidity. To provide accuracy for the Tw calculation, an empirical equation is established using regression analysis. This study defines the empirical equation as Tw = − 4.391976 + 0.0198197 RH + 0.526359 Td + 0.00730271 RH · Td + 2.4315 × 10 − 4 RH 2 − 2.58101 × 10 − 5 Td · RH 2 , where Td is the air temperature in °C and RH is the relative humidity in %. This equation applies to a temperature of 20~45 °C and RH of 40~99%. The fit is better than that for the Stull equation in this range. The prediction accuracy is 0.022 °C and there is no fixed pattern for the error distribution for the range of Td and RH. The measurement uncertainty for Tw values for thermometer and humidity sensors that are not calibrated is 1.4~2.2%. If these sensors are calibrated, the measurement uncertainty for Tw values is 0.16~0.28 °C. Therefore, well-calibrated sensors are necessary to enhance the accuracy of the Tw predictive equation. [ABSTRACT FROM AUTHOR]

Nineteen limb-viewing data sets (occultation, passive thermal, and UV scattering) and two nadir upper tropospheric humidity (UTH) data sets are intercompared and also compared to frost-point hygrometer balloon sondes. The upper troposphere considered here covers the pressure range from 300–100 hPa. UTH is a challenging measurement, because concentrations vary between 2–1000 ppmv (parts per million by volume), with sharp changes in vertical gradients near the tropopause. Cloudiness in this region also makes the measurement challenging. The atmospheric temperature is also highly variable ranging from 180–250 K. The assessment of satellite-measured UTH is based on coincident comparisons with balloon frost-point hygrometer sondes , multi-month mapped comparisons, zonal mean time series comparisons, and coincident satellite-to-satellite comparisons. While the satellite fields show similar features in maps and time series, quantitatively they can differ by a factor of 2 in concentration, with strong dependencies on the amount of UTH. Additionally, time-lag response-corrected Vaisala RS92 radiosondes are compared to satellites and the frost-point hygrometer measurements. In summary, most satellite data sets reviewed here show on average ∼30 % agreement amongst themselves and frost-point data but with an additional ∼30 % variability about the mean bias. The Vaisala RS92 sonde, even with a time-lag correction, shows poor behavior for pressures less than 200 hPa. [ABSTRACT FROM AUTHOR]

As the near-surface atmosphere over the Antarctic Plateau is cold and pristine, its physico-chemical conditions resemble to a certain extent those of the high-troposphere where cirrus clouds form. In this paper, we carry out an observational analysis of two shallow fog clouds forming at cirrus-temperatures - that is, temperatures lower than 235 K - at Dome C, inner Antarctic Plateau. The combination of lidar profiles with temperature and humidity measurements from advanced thermo-hygrometers along a 45-m mast makes it possible to characterise the formation and development of the fog. High supersaturations with respect to ice are observed before the initiation of fog and the values attained suggest that the nucleation process at play is the homogeneous freezing of solution aerosol droplets. To our knowledge, this is the first time that in situ observations show that this nucleation pathway can be at the origin of an ice fog. Once nucleation occurs, the relative humidity gradually decreases down to subsaturated values with respect to ice in a few hours, likely owing to vapour deposition onto ice crystals and turbulent mixing. The development of fog is tightly coupled with the dynamics of the boundary-layer which, in the first study case, experiences a weak diurnal cycle while in the second case, transits from a very stable to a weakly stable dynamical regime. Overall, this paper highlights the potential of the site of Dome C for carrying out observational studies of cloud microphysical processes in natural conditions and using in-situ ground-based instruments. [ABSTRACT FROM AUTHOR]

This is a review of high-frequency methods for measuring and controlling the humidity of various materials. The moisture of cotton seeds is a major factor affecting their qualitative and quantitative characteristics in technologies for their storage, transport, and processing. Thus, direct humidity measurements of cotton seeds during processing is an important problem. A mathematical model of a high-frequency hygrometer for cotton seeds is constructed in which the test material is represented as a complicated dielectric in an electric field. A substitution circuit containing a capacitance between electrodes is proposed, along with capacitances and resistances corresponding to different forms of polarization. Four variants of the substitution circuit are examined which approximately describe the dependence of the tangent of the dielectric loss angle on the frequency of the electromagnetic field. It is shown that the simplest parallel two-component RC substitution circuit corresponds most closely to the actual object of measurement at frequencies of 105–108 Hz. [ABSTRACT FROM AUTHOR]

• We report a new method for humidity measurements by using human hairs. • A short segment of a single strand of hair mounted on a machined jig simply constitutes a mechanical resonator. • The hair resonator offers high spatial and temporal resolutions with the aid of its miniaturized dimension. • Historical hair hygrometers are successfully revisited with improved performance. Hairs have long been used for humidity sensing with the aid of their unique property, elongation upon the increase of ambient humidity. However, relatively long strands of hairs are required to induce measurable length change. While such long strands of hairs amplify the readout signal, they, in turn, compromise the spatiotemporal resolution. Here, we revisit the hair hygrometer, firstly demonstrated by a Swiss physicist and geologist, Horace Bénédict de Saussure in 1783, by making suspended string resonators with a short segment of human hairs. A short segment of human hair is placed onto a substrate with a through-hole and then firmly fixed under tension to make a taut suspended string. As a final step, a thin gold layer is locally deposited onto the suspended hair through a shadow mask. While the prepared hair resonator is driven by a piezo actuator, its resonance frequency is optically measured. Measurements confirm that the resonance frequency of the hair resonator decreases as the relative humidity increases. The water absorption decreases both the tension and the stiffness of the hair resonator and increases the inertial mass of the hair resonator, all of which contribute to the reduction of the resonance frequency. [ABSTRACT FROM AUTHOR]

Copyright of Listy Cukrovarnicke a Reparske is the property of VUC Praha a.s. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new technique of depositing a poly(vinyl alcohol) (PVA) coating with an airbrush on the cylindrical surface of an optical fiber with real‐time spectral monitoring is presented. The method is applied for creating hygroscopic PVA coating as a part of the tilted‐fiber Bragg‐grating (TFBG)‐assisted fiber hygrometer samples. By monitoring the transmission spectra of the samples placed in a climatic chamber with variable relative humidity, the performance of the resulting coating is evaluated. Experimental data are presented, demonstrating the effectiveness of the described technique for humidity‐sensing purposes. [ABSTRACT FROM AUTHOR]

A concept of a highly sensitive and fast-response airborne optoelectronic hygrometer, based on the absorption spectroscopy with laser light tuned to an intense ro-vibronic absorption line of H2O in the 1391- 1393 nm range is presented. The target application of this study is airborne atmospheric measurements, in particular at the top of troposphere and in stratosphere. The cavity ring-down spectroscopy was used to achieve high sensitivity. In order to avoid interference of the results by water desorbed from the instrument walls, the open-path solution was applied. Tests of the instrument, performed in a climatic chamber, have shown some advantages of this concept over typical hygrometers designed for similar applications. [ABSTRACT FROM AUTHOR]

Accurate measurement of water vapor in the climate-sensitive region near the tropopause is very challenging. Unexplained systematic discrepancies between measurements at low water vapor mixing ratios made by different instruments on airborne platforms have limited our ability to adequately address a number of relevant scientific questions on the humidity distribution, cloud formation and climate impact in that region. Therefore, during the past decade, the scientific community has undertaken substantial efforts to understand these discrepancies and improve the quality of water vapor measurements. This study presents a comprehensive intercomparison of airborne state-of-the-art in situ hygrometers deployed on board the DLR (German Aerospace Center) research aircraft HALO (High Altitude and LOng Range Research Aircraft) during the Midlatitude CIRRUS (ML-CIRRUS) campaign conducted in 2014 over central Europe. The instrument intercomparison shows that the hygrometer measurements agree within their combined accuracy (±10% to 15 %, depending on the humidity regime); total mean values agree within 2.5 %. However, systematic differences on the order of 10% and up to a maximum of 15% are found for mixing ratios below 10 parts per million (ppm) H2O. A comparison of relative humidity within cirrus clouds does not indicate a systematic instrument bias in either water vapor or temperature measurements in the upper troposphere. Furthermore, in situ measurements are compared to model data from the European Centre for Medium-Range Weather Forecasts (ECMWF) which are interpolated along the ML-CIRRUS flight tracks. We find a mean agreement within ±10% throughout the troposphere and a significant wet bias in the model on the order of 100% to 150% in the stratosphere close to the tropopause. Consistent with previous studies, this analysis indicates that the model deficit is mainly caused by too weak of a humidity gradient at the tropopause. [ABSTRACT FROM AUTHOR]

This paper assesses the performance of water vapor measurements by Sondeur Atmosphérique du Profild’ Humidité Intertropicale par Radiométrie (SAPHIR), microwave limb sounder (MLS), and the global reanalysis water vapor data [Modern Era Retrospective analysis for Research and Applications (MERRA) and European Center for Medium-Range Weather Forecasts reanalysis (ERA) interim] by comparing with water vapor-measured in situ by cryogenic frost-point hygrometer (CFH) at two tropical stations, Trivandrum (8.5°N, 76.9°E) and Hyderabad (17.47°N, 78.58°E). The iMet-1 radiosonde though overestimates frost-point temperature (3%–5%) in the 4–10-km altitude region with respect to CFH, it agrees well with CFH observations in the upper troposphere and the lower troposphere with a mean difference <2% and ~1%, respectively. SAPHIR–CFH intercomparison is done for the troposphere region, and MLS, MERRA, and ERA interim are compared with CFH in the lower stratosphere region. SAPHIR and CFH comparison shows a reasonable agreement between both the datasets with a relative humidity difference of about 15% in the lower and middle troposphere and a dry bias of ~40% in the upper troposphere. Intercomparison between CFH and MLS water vapor mixing ratios (WVMRs) shows a small wet bias (−10% to −20%) for the MLS in the lower stratospheric region between 100 and 50 hPa and a small dry bias (<10%) above that region. This paper shows that the MLS always underestimates when the CFH WVMR is greater than 6 ppmv and overestimates when the WVMR is less than 2 ppmv. The intercomparison of CFH with MERRA and ERA interim specific humidity shows results similar to that with MLS. [ABSTRACT FROM AUTHOR]

Capacitive hygrometers are widely used in industrial and environmental measurements. One of the limitations of these sensors is their temperature dependence. While in temperatures beyond 50 °C the effect has been proven to be significant, for standard conditions in calibration laboratories the magnitude of this dependence has not been rigorously studied. This paper presents the analysis and results of a study of the temperature influence in the calibration of capacitive hygrometers designed for monitoring environmental conditions. Ninety measurements were taken on 15 models of capacitive hygrometers using a two-pressure humidity generator between 30%rh and 80%rh and temperatures from 20 to 30 °C. A three-way analysis of variance (ANOVA) was used to evaluate the data. The results show that the calibration correction is independent of the temperature for the conditions considered; however, there is a correlation between the temperature and the devices, indicating that the gradients in temperature affect each technology of fabrication in a different way. [ABSTRACT FROM AUTHOR]

This paper describes the dew point temperature hygrometer as a complex microsystem manufactured using inkjet printing directly on the surface of a Peltier couple heat pump. The principle of the structure’s fabrication is similar to that of other sensors printed directly on textiles, paper or thin foils, but is much more difficult to perform. Both the principle of specific detector construction as well as some technological aspects are discussed in the paper. All three elements of the detector i.e. thermoresistor, heater and impedance dew detector are widely characterized to ascertain the performance of each. Final tests of the whole dew point hygrometer operation parameters are carefully reported and discussed in the conclusions. [ABSTRACT FROM AUTHOR]

To investigate if the LI-COR humidity sensor can be used as a replacement of the Lyman-alpha sensor for airborne applications, the measurement data of the Lymanalpha and several LI-COR sensors are analysed in direct intercomparison flights on different airborne platforms. One vibration isolated closed-path and two non-isolated open-path LI-COR sensors were installed on a Dornier 128 twin engine turbo-prop aircraft. The closed-path sensor provided absolute values and fluctuations of the water vapour mixing ratio in good agreement with the Lyman-alpha. The signals of the two open-path sensors showed considerable high-frequency noise, and the absolute value of the mixing ratio was observed to drift with time in this vibrational environment. On the helicopter-towed sensor system Helipod, with very low vibration levels, the open-path LI-COR sensor agreed very well with the Lyman-alpha sensor over the entire frequency range up to 3 Hz. The results show that the LI-COR sensors are well suited for airborne measurements of humidity fluctuations, provided that a vibrationless environment is given, and this turns out to be more important than close sensor spacing. [ABSTRACT FROM AUTHOR]

The properties of fast hygrometers, the Lyman-Alpha and different LICOR humidity sensors, are analysed in direct intercomparison flights on different airborne platforms. One vibration isolated closed-path and two non-isolated open path LICOR sensors were installed on the twin engine turbo-prop aircraft Dornier 128. The closed-path sensor provided absolute values and fluctuations of the water vapour mixing ratio in good agreement with the Lyman-Alpha. The signals of the two open-path sensors showed considerable high frequency noise, and the absolute value of the mixing ratio was observed to drift with time in this vibrational environment. On the helicopter-towed sonde Helipod with very low vibration level the open-path LICOR sensor agreed very well with the Lyman-Alpha over the entire frequency range up to 3 Hz. The results show that the LICOR sensors are well suited for airborne measurements of humidity fluctuations, provided that a vibrationsless environment is given, and this turns out to be more important than close sensor spacing. [ABSTRACT FROM AUTHOR]

Understanding the mechanism of humidity transduction calls for experimental data and a theory to interpret the data and design new experiments. A comprehensive theory of humidity transduction must start with agreement on what humidity parameters are measured by hygroreceptors and processed by the brain. Hygroreceptors have been found in cuticular sensilla of a broad range of insect species. Their structural features are far from uniform. Nevertheless, these sensilla always contain an antagonistic pair of a moist cell and a dry cell combined with a thermoreceptive cold cell. The strategy behind this arrangement remains unclear. Threemainmodels of humidity transduction have been proposed. Hygroreceptors could operate as mechanical hygrometers, psychrometers or evaporation detectors. Each mode of action measures a different humidity parameter. Mechanical hygrometers measure the relative humidity, psychrometers indicate the wet-bulb temperature, and evaporimeters refer to the saturation deficit of the air. Here we assess the validity of the different functions by testing specific predictions drawn from each of themodels. The effect of air temperature on the responses to humidity stimulation rules out the mechanical hygrometer function, but it supports the psychrometer function and highlights the action as evaporation rate detector. We suggest testing the effect of the flow rate of the air stream used for humidity stimulation. As the wind speed strongly affects the power of evaporation, experiments with changing saturation deficit at different flow rates would improve our knowledge on humidity transduction. [ABSTRACT FROM AUTHOR]

This study developed a novel psychrometer design in which air is pumped by a 0.35-W minifan through a chamber with a hanging wet wick and a single-packaged contactless infrared thermometer aimed at the wick. The thermometer is small sized, low cost, commercially available, and comes factory calibrated with a digital I 2 C communication port. It can measure the temperatures of the package itself (dry bulb) and the wick surface (wet bulb). For the fast conversions of relative humidity (RH) and vapour pressure deficit Δ e from both dry- and wet-bulb temperatures in a low-end microcontroller, a method for deriving a fifth-order polynomial approximation equation for saturation vapour pressure e s is presented. This equation enables the calculation to be rapidly executed on the microcontroller. An error analysis of conversion conducted taking the Goff–Gratch equations as a standard indicates that at temperatures ranging from 0 °C to 55 °C, the computational accuracy for RH reading is within +0.02 to −0.005, compared with ±0.1 derived for the Magnus form; in addition, the accuracy for Δ e is within +0.002 to −0.0013 hPa, compared with +0.23 to −0.024 hPa derived for the Magnus form. For predicting the water evaporation of the psychrometer according to its own climate parameters, a model based on the simplified Penman Equation was constructed; the predictive error for water mass loss is within ±2 g for a 325-g evaporation. [ABSTRACT FROM AUTHOR]

A joint project between the National Institute of Metrology Thailand (NIMT) and the Thai Meteorology Department (TMD) was established for improving the traceability of meteorology measurements at automatic weather stations (AWSs) in Thailand. The project aimed to improve traceability of air temperature, relative humidity and atmospheric pressure by implementing on-site calibration facilities and developing of new calibration procedures. First, new portable calibration facilities for air temperature, humidity and pressure were set up as working standard of the TMD. A portable humidity calibrator was applied as a uniform and stable source for calibration of thermo-hygrometers. A dew-point hygrometer was employed as reference hygrometer and a platinum resistance thermometer (PRT) traceable to NIMT was used as reference thermometer. The uniformity and stability in both temperature and relative humidity were characterized at NIMT. A transportable pressure calibrator was used for calibration of air pressure sensor. The estimate overall uncertainty of the calibration setup is 0.2 K for air temperature, 1.0 % for relative humidity and 0.2 hPa for atmospheric pressure, respectively. Second, on-site calibration procedures were developed and four AWSs in the central part and the northern of Thailand were chosen as pilot stations for on-site calibration using the new calibration setups and developed calibration procedures. At each station, the calibration was done at the minimum temperature, average temperature and maximum temperature of the year, for air temperature, 20 %, 55 % and 90 % for relative humidity at the average air temperature of that station and at a one-year statistics pressure range for atmospheric pressure at ambient temperature. Additional in-field uncertainty contributions such as the temperature dependence on relative humidity measurement were evaluated and included in the overall uncertainty budget. Preliminary calibration results showed that using a separate PRT probe at these AWSs would be recommended for improving the accuracy of air temperature measurement. In case of relative humidity measurement, the data logger software is needed to be upgraded for achieving higher accuracy of less than 3 %. For atmospheric pressure measurement, a higher accuracy barometer traceable to NIMT could be used to reduce the calibration uncertainty to below 0.2 hPa. [ABSTRACT FROM AUTHOR]

The term “Time-zero”, i.e., the time for the start of autogenous shrinkage measurement, is usually used for estimating the cracking potential of structural components. Accurate determination of the “time-zero” is therefore critical for autogenous shrinkage measurement, which is the main objective of this study. There is a general agreement about the existence of a relationship between autogenous shrinkage and RH changes in hardening cement paste. An improved hygrometer method was developed for monitoring the change of internal RH in cement pastes 1 h after casting. This provides immediate experimental results of RH change for determining the “time-zero”. It indicates that the internal RH of cement pastes does not decrease immediately after the final setting time. A new “time-zero” is defined as the onset of internal RH drop, which is more reasonable for estimating the cracking potential of cement-based materials, compared to the “time-zero” represented by the final setting time. [ABSTRACT FROM AUTHOR]

A prototype thermohygrometer was built with data logger base on an Arduino board to measure temperature and humidity inside buildings, which consisted of an Arduino Mega 2560 256K memory microprocessor, 16MHZ frequency, DHT 22 sensor with precision: ± 0.5°C, ± 1°C and 10s of response for temperature, as well as ± 2% of relative humidity of precision with 5s of response for relative humidity. Finally, an SD reader module with 32GB of memory for the data logger registry was added. The temperature and humidity were measured every 10 minutes for 24 hours where the functionality of the thermo-hygrometer was checked; however, statistically significant differences were obtained (p> 0.05) for humidity. However, in spite of the unexpected differences with the humidity variable which it is necessary to follow methodological procedures for its optimization, was possible to build a prototype thermo-hygrometer that registered similar values for the temperature to designs validated in the commercial thermo-hygrometer market. The built prototype thermo-hygrometer was feasible and with a lower cost, which means it can be used in studies on indoor temperature measurement in buildings. [ABSTRACT FROM AUTHOR]

The microclimate at work is a very important element that puts a mark on worker health. The paper presents the methodology for determining and appreciating the professional microclimate through its components: air temperature; Relative air humidity; Airflow velocity; Caloric radiation; The working surface temperature at work. The aim of the paper is to educate in order to obtain an appropriate microclimate to avoid overworking of the visual analyzer, stimulate higher nerve activity processes, increase working capacity, prevent occupational diseases, work accidents and chronic fatigue. [ABSTRACT FROM AUTHOR]

A prototype optoelectronic hygrometer, based on absorption of laser light tuned to absorption specific rovibronic absorption line of H2O at 1364.68961 nm is described. Target application is meteorology, in particular precise and fast measurements of small-scale humidity fluctuations in turbulent atmospheric flows. Tests of the prototype instrument performed in the atmospheric boundary layer have proven the advantage of this optoelectronic sensor over typical, commercially available UV hygrometers designed for similar applications [ABSTRACT FROM AUTHOR]

The Russian national humidity standard of gases has been modernized in order to increase the number of reproducible quantities of humidity (relative humidity, dew/frost-point temperature, mole fraction) and to extend the humidity and operating temperature ranges. The basis of the standard comprises two humidity generators with operating temperature ranges from $$5\,^{\circ }\hbox {C}$$ to $$90\,^{\circ }\hbox {C}$$ and from $$-60\,^{\circ }\hbox {C}$$ to $$15\,^{\circ }\hbox {C}$$ . The common working range (from $$5\,^{\circ }\hbox {C}$$ to $$15\,^{\circ }\hbox {C}$$ ) allows comparison of the generators. The generators use the two-pressure method to generate humid gas defined in terms of the relative humidity (from 5 %rh to 98 %rh at temperatures from $$90\,^{\circ }\hbox {C}$$ to $$-60\,^{\circ }\hbox {C}$$ ) and the one-pressure (or phase equilibrium) method to generate humid gas defined in terms of the vapor mole fraction (from 0.6 ppm to $$700\times 10^{3}$$ ppm) and dew/frost-point temperature (from $$-79\,^{\circ }\hbox {C}$$ to $$90\,^{\circ }\hbox {C}$$ ). The expanded uncertainty in the relative humidity is no more than 0.2 %rh, no more than 1.2 % in the vapor mole fraction, and no more than $$0.12\,^{\circ }\hbox {C}$$ in the dew/frost-point temperature. The ordinary hygrometers are traceable to the national primary standard in accordance with the state hierarchical chain for measuring means of gas humidity. The state hierarchical chain consists of three branches for means of measurements: (a) mole fraction, (b) dew/frost-point temperature, and (c) relative humidity with each branch represented as the scheme: primary standard-secondary standard-working standard-ordinary hygrometer. Calibration and verification of working standards and ordinary hygrometers, and their traceability to the primary standard use methods of (i) direct measurements, (ii) direct comparison, or (iii) comparison with a comparator. [ABSTRACT FROM AUTHOR]

Over the past decades, virtual meters or sensors have been rapidly developed and widely adopted within a number of different fields especially in the building section, and have enabled many intelligent features that would otherwise not be possible and economical. Ambient wet-bulb temperature is normally measured either by a psychrometer, or a combination of dry-bulb temperature sensor and relative humidity sensor. These physical sensors are notoriously costly and problematic considering their accuracy and reliability. Furthermore, ambient wet-bulb temperature is critical in a water-cooled chiller plant to enhance its holistic energy efficiency through specific control strategies, such as cooling tower temperature relief, condenser water supply temperature reset, and so on. This paper introduces a virtual ambient wet-bulb sensor through a black-box method using one low-cost dry-bulb temperature sensor and local weather data, either typical meteorological year (TMY) or real-time weather data. A control algorithm for the cooling tower fan operation was also developed to calibrate this virtual wet-bulb sensor, thus to minimize its measuring deviation. Two case studies in Beijing, China and Texas, USA were adopted to demonstrate the feasibility of this strategy under different climate scenarios. It shows that the virtual sensor combined with the control algorithm has high potential to improve the accuracy of the ambient wet-bulb temperature, and guarantee the chiller plant performance by the proposed control strategies. [ABSTRACT FROM AUTHOR]

This paper deals with the development of an accurate and precise humidity sensor, which is based on the extension of Thompson and Lampard theorem and a sol–gel-based thermally and chemically stable metal oxide thin film. In light of the extension of the theorem, most appropriate conductors are shaped around the material and the resulting sensor has cross conductance, which is the function of thickness only. It is fabricated and tested for different ranges of humidity. It is found that the fabricated sensor has outstanding static and dynamic characteristics. [ABSTRACT FROM PUBLISHER]

In this paper, we are proposing a novel rapid sol–gel thin-film porous metal–oxide-based surface acoustic wave (SAW) humidity sensor. For the SAW sensor, the center frequency of 433.92 MHz has been selected, and the device has been configured in a high-frequency oscillator circuit to explore the frequency response in the presence of water vapor. The sensitive thin film of sol–gel $\gamma $ -Al2O3 coated with a drop dry method offers very high surface-to-volume ratio with the distribution of micropores making the sensor highly sensitive for moisture detection. Pore morphologies of the film have been studied by field emission scanning electron microscope and atomic force microscopy. The \gamma $ phase of alumina of the film has been characterized with X-ray diffraction. The sensor has been tested from 3% relative humidity (RH) to 85% RH. The proposed sensor has very fast ( T_{r}= 1 s) response time and excellent yield ratio in comparison with the conventional commercial capacitive aluminum oxide sensor. The sensitivity (3%–20% RH) and the hysteresis (3%–85% RH) are found to be 120-Hz/% RH and 0.3%, respectively. The sensor can be useful for different applications, including moisture dispersion inside electronic gadgets, dryers, ovens, textile production, semiconductor device processing, food processing, medicine, and sealed packages. [ABSTRACT FROM PUBLISHER]

A collimated surface acoustic wave (SAW) circles around the equator of a sphere hundreds of times. Because of the long distance travel of the collimated SAW, a small change in the SAW propagation caused by the environment of the sphere can be accumulated as a measurable range in amplitude and/or in delay time. So, a spherical SAW device enables highly sensitive water-vapor measurements. In this paper, deep sub $$\upmu \hbox {mol}{\cdot }\hbox {mol}^{-1}$$ water-vapor detection by 1 mm diameter quartz crystal ball SAW sensors is described. To measure such a low water-vapor concentration in real time, it is necessary to compensate the temperature dependence of the ball SAW sensor, which is about 20 $$\hbox {ppm}{\cdot }^{\circ }\hbox {C}^{-1}$$ in delay time change. A dual-frequency burst analog detector was developed for the temperature compensation in real time. By using a harmonic SAW sensor, which was excited by 80 MHz and 240 MHz at the same time, it was confirmed that the delay time drift for a temperature range of $$21.0\, ^{\circ }\hbox {C} \pm 1.0\,^ {\circ }\hbox {C}$$ became less than 0.05 ppm in delay time change. By using dual-ball SAW sensors (which included a 150 MHz sensor with a water-vapor sensitive layer and a 240 MHz sensor as a reference), water-vapor concentrations from 0.1 $$\upmu \hbox {mol}{\cdot }\hbox {mol}^{-1}$$ to $$5\; \upmu \hbox {mol}{\cdot }\hbox {mol}^{-1}$$ were successfully measured. It appears that the delay time change is proportional to the square root of the water-vapor concentration. The detection limit determined by the electrical noise of the system was estimated at $$0.01\; \upmu \hbox {mol}{\cdot }\hbox {mol}^{-1}$$ . [ABSTRACT FROM AUTHOR]

The goal of interlaboratory comparisons is to verify the competence of accredited or non-accredited laboratories, including verification of the reported measurement uncertainties, whenever possible. An interlaboratory comparison consists of measurement results of a laboratory and a reference laboratory which is competent to run the comparison and provides traceability at the required uncertainty level. In Turkey, the demand for an interlaboratory comparison in the humidity field increased drastically in parallel to an increasing number of accredited laboratories in this field. Therefore, a national interlaboratory comparison in the scope of relative humidity in the range between 11 %rh and 95 %rh at $$23\, {}^{\circ }\hbox {C}$$ was initiated by TUBITAK UME in 2011. Two hygrometers were calibrated at TUBITAK UME in the above-mentioned range and characterized in terms of long-term stability, temperature dependence, and hysteresis. One of the hygrometers is used throughout this comparison. The second one was kept aside as a backup device in case of a malfunction of the first device. Organization and evaluation of the interlaboratory comparison in the scope of relative humidity were performed according to the EN ISO/IEC 17043:2010 'Conformity assessment-general requirements for proficiency testing' among thirteen national laboratories. Evaluation of comparison results are performed by normalized error analysis. It was found that among the 95 realized points of comparison, 85 (89 %) had $$E_{n} \le 1$$ and only 10 (11 %) had $$E >1$$ . [ABSTRACT FROM AUTHOR]

Moisture content is a key factor regardless of the activity carried out inside the natural gas industry (production, processing, transmission, etc.). Not only does the efficiency of the final product, known as heating value, decrease when the water content is high, but it can also trigger potentially dangerous conditions due to the formation of hydrates, that can block pipelines and damage pumping devices and produce other negative effects. For these reasons, accurate measurement and control of humidity is absolutely essential. However, current practice for such moisture measurements is for the devices to be calibrated at atmospheric pressure and in nitrogen or air as the matrix gas, conditions that vary significantly from those present in the actual industrial process. For that, eleven hygrometers based on different measurement principles (chilled-mirror, electrolytic sensor, a spectroscopic analyzer, polymeric and metal oxide humidity sensors) have been compared at facilities of the main carrier of natural gas in Spain, using natural gas at absolute pressures between 0.1 MPa and 6 MPa, and for a range of water content from 13 ppm v to 250 ppm v . Their relative performance is described in terms of the response times, long term stability, hysteresis and behaviour under large pressure changes. Most instruments, exceptions are detailed in the article, show good behaviour regarding response time, hysteresis and under sudden pressure changes. In contrast, drift can be identified in most of the aluminium oxide probes tested. [ABSTRACT FROM AUTHOR]

This paper proposes a method to resolve a strong coupling between temperature and relative humidity in drying room control systems. The coupling issue not only affects the control accuracy but also causes system instability, unnecessary adjustment, and extra energy consumption. A real-time temperature and relative humidity decoupling control method is reported in this paper. An improved aspirated psychrometer was used as a relative humidity measurement unit, which achieved relative humidity measurement accuracy of ±0.7%. The decoupling approach was developed based on a large real-time drying room, whose physical size was 22 × 15 × 3.5 m. A decoupling approach was developed using the adaptive neuro-fuzzy inference system for the control of temperature and relative humidity in the drying room. The simulated result shows that after the decoupling treatment, the relative humidity fluctuation was reduced from ±2.5% to ±0.6%. [ABSTRACT FROM AUTHOR]

This paper describes a tunable diode laser-based dual-channel photoacoustic (PA) humidity measuring system primarily designed for aircraft-based environment research. It is calibrated for total pressure and water vapor (WV) volume mixing ratios (VMRs) possible during airborne applications. WV VMR is calculated by using pressure-dependent calibration curves and a cubic spline interpolation method. Coverage of the entire atmospheric humidity concentration range that might be encountered during airborne measurements is facilitated by applying an automated sensitivity mode switching algorithm. The calibrated PA system was validated through laboratory and airborne intercomparisons, which proved that the repeatability, the estimated accuracy and the response time of the system are 0.5 ppmV or 0.5 % of the actual reading (whichever value is the greater), 5 % of the actual reading within the VMR range of 1-12 000 ppmV and 2 s, respectively. The upper detection limit of the system is theoretically about 85 000 ppmV, limited only by condensation of water vapor on the walls of the 318 K heated PA cells and inlet lines, and was experimentally verified up to 20 000 ppmV. The unique advantage of the presented system is its applicability for simultaneous water vapor and total water volume mixing ratio measurements. [ABSTRACT FROM AUTHOR]

The MOZAIC Capacitive Hygrometer (MCH) is usually operated onboard of passenger aircraft in the framework of MOZAIC (Measurement of Ozone by AIRBUS In-Service Aircraft). In order to evaluate the performance of the MCH, it was operated aboard a Learjet 35A aircraft as part of the CIRRUS-III field study together with a closed-cell Lyman-α fluorescence hygrometer (FISH) and an open path tunable diode laser system (OJSTER) for water vapour measurement. After reducing the data set to MOZAICrelevant conditions, the 1Hz relative humidity (RH) cross correlation between MCH and reference instruments FISH (clear sky) and OJSTER (in-cirrus) yielded a remarkably good agreement of R² = 0.97 and slope m = 0.96 and provided the MCH uncertainty of 5% RH. Probability distribution functions of RH deduced from MCH and reference instruments agreed well over the entire range of observations. The main limitation for the use of MCH data is related to sensor temperatures below the calibration limit of Tsensor = -40°C (corresponds to ambient temperature of Tambient = -70°C at typical cruising speed of long-haul passenger aircraft), which causes a delay in the sensor's time response. Good performance of MCH for clear sky as well as for in-cirrus conditions demonstrated the sensor robustness also for operation inside ice clouds. [ABSTRACT FROM AUTHOR]

A microcontroller-based digital hygrometer system using a low-cost moisture sensor in the range of 3.7–100 ppm has been developed. The sensor is of capacitive type and consists of nanoporous thin film of alumina (\gamma - \Al2\O3) dip coated in between two parallel gold electrodes onto an alumina substrate. The behavior of the sensor has been modeled with an object to develop a signal processing circuit to convert capacitance change into frequency. The detection electronics circuit is based on a relaxation oscillator whose output is suitable for interfacing with a digital device. The sensor has been characterized with the circuit and then output frequency is calibrated in terms of ppm. The accuracy of the digital hygrometer when compared with the commercial dew point meter is found to be $\pm\!$ 1 PPM. [ABSTRACT FROM PUBLISHER]

The AquaVIT-1 intercomparison of atmospheric water vapor measurement techniques was conducted at the aerosol and cloud simulation chamber AIDA (Aerosol Interaction and Dynamics in the Atmosphere) at the Karlsruhe Institute of Technology, Germany, in October 2007. The overall objective was to intercompare state-of-the-art and prototype atmospheric hygrometers with each other and with independent humidity standards under controlled conditions. This activity was conducted as a blind intercomparison with coordination by selected referees. The effort was motivated by persistent discrepancies found in atmospheric measurements involving multiple instruments operating on research aircraft and balloon platforms, particularly in the upper troposphere and lower stratosphere, where water vapor reaches its lowest atmospheric values (less than 10 ppm). With the AIDA chamber volume of 84m3, multiple instruments analyzed air with a common water vapor mixing ratio, by extracting air into instrument flow systems, by locating instruments inside the chamber, or by sampling the chamber volume optically. The intercomparison was successfully conducted over 10 days during which pressure, temperature, and mixing ratio were systematically varied (50 to 500 hPa, 185 to 243 K, and 0.3 to 152 ppm). In the absence of an accepted reference instrument, the absolute accuracy of the instruments was not established. To evaluate the intercomparison, the reference value was taken to be the ensemble mean of a core subset of the measurements. For these core instruments, the agreement between 10 and 150 ppm of water vapor is considered good with variation about the reference value of about ±10% (±1σ). In the region of most interest between 1 and 10 ppm, the core subset agreement is fair with variation about the reference value of ±20% (±1σ). The upper limit of precision was also derived for each instrument from the reported data. The implication for atmospheric measurements is that the substantially larger differences observed during in-flight intercomparisons stem from other factors associated with the moving platforms or the non-laboratory environment. The success of AquaVIT-1 provides a template for future intercomparison efforts with water vapor or other species that are focused on improving the analytical quality of atmospheric measurements on moving platforms. [ABSTRACT FROM AUTHOR]

We investigate the effects of humidity on the vibrations of carbon nanotubes (CNTs) using two types of CNT cantilevers: open-ended and close-ended CNT cantilevers. As the humidity increases, the resonant frequency of the open-ended CNT cantilever decreases due to the adsorption of water molecules onto the CNT tip, whereas that of the close-ended CNT cantilever increases probably due to the change in the viscosity of the air surrounding the CNT cantilever, which is negatively correlated with the humidity of air. Our findings suggest that a close-ended CNT cantilever is more suitable for a quick-response and ultrasensitive hygrometer because it continuously reads the viscosity change of moist air in the vicinity of the CNT. [ABSTRACT FROM AUTHOR]

Natural bentonite (BNT) nanoclay and a polyimide (PI) film were used to fabricate durable bilayer-type actuators driven by airborne moisture. The BNT/PI actuators, optimized for the layer thickness and dimensions, displayed a linear response over the relative humidity (RH) range of 4 – 92% with the curvature sensitivity of 0.35 cm−1%RH−1. It also showed good selectivity to moisture against common organic solvent vapors and excellent reproducibility for up to 200 consecutive operations. Systematic investigations on the materials properties for the individual layers revealed that the bending occurred upon the adsorption of water vapor because the BNT layer underwent greater volume expansion and loss of stiffness than the PI layer. These BNT/PI actuators were successfully applied to create three different prototypes of user-friendly, stand-alone hygrometers: a clock-like hygrometer, an emoticon-display hygrometer, and a humidity-switch-based LED hygrometer. • A new moisture-driven bilayer actuator using water-expandable BNT nanoclays. • Linear and reliable bending over a wide RH range of 4–92% with sufficient sensitivity and selectivity to water vapor. • Bending mechanism based on the humidity-driven expansion induced by water absorption of the BNT. • Development of three prototypes of user-friendly and stand-alone hygrometers as well as a humidity switch. [ABSTRACT FROM AUTHOR]

The bioclimatic factor is a useful tool in scientific research because it provides a wide range of assessment techniques of either positive or negative influences that a climate of a region may have on human health. This study focuses on the analysis of the thermo-hygrometric index (THI), which was calculated according to air temperature and humidity value variations throughout the year, to provide information on the extent and intensity of the area of bioclimatic comfort and/or discomfort in Southern Dobrogea tableland area, subjected to various climatic influences. [ABSTRACT FROM AUTHOR]

Accurately determining seed moisture and efficiently drying seeds is a critically needed capacity for seed management. In this article, instructions are provided to make a moisture test chamber for easily assessing seed moisture content with a handheld hygrometer. In addition, I provide instructions for assembling a relatively inexpensive pressurized seed drier from readily available components using simple hand tools. Basic instructions for using the hygrometer and test chamber and the dryer are also provided. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous LaFeO3 with high surface area and pore volume was prepared through a nanocasting route by using mesoporous silica SBA-15 as a hard template. The structure and chemical composition of the sample were characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS). The humidity sensing properties of the mesoporous LaFeO3 were investigated. Impedance greatly changes by more than five orders magnitude (1.7×106 to 4.5kΩ) when the relative humidity varies from 11% to 98% at 10Hz, and it also exhibits the satisfactory response time, hysteresis and stability. The sensor utilizing mesoporous LaFeO3 via nanocasting method displays superior humidity performance compared to that using bulk LaFeO3 via sol–gel technique. Such sensing behavior of the mesoporous LaFeO3 can be attributed to the high surface area (83.2m2/g) and porosity, which lead to highly effective interaction between the water molecules and the surface active sites. A possible mechanism is discussed to explain the excellent performance of the humidity sensing device using the mesoporous LaFeO3. [Copyright &y& Elsevier]

Abstract: Humidity sensors were made by coating 25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene (TBHC) and 5-(4′-nitrophenyl)azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene (NTBHC) thin films on a gold electrode of a quartz crystal microbalance (QCM). The thin films were analyzed by atomic force microscopy (AFM). The humidity sensing properties, including sensitivity, sensing linearity, hysteresis, cross-sensitivity effects and long-term stability were also investigated. Water vapor molecules that were adsorbed onto the NTBHC thin film exhibited a larger frequency shift than those adsorbed onto TBHC thin films. Adsorption dynamic analysis and a molecular mechanical calculation (of the association constant) were made to elucidate the way in which a substituent on the upper and lower rims of calix[4]arene increases the sensitivity to humidity. [Copyright &y& Elsevier]