Factors controlling upper tropospheric relative humidity

Directory of Open Access Journals (Sweden)

B. Kärcher

2004-03-01

Full Text Available Factors controlling the distribution of relative humidity in the absence of clouds are examined, with special emphasis on relative humidity over ice (RHI under upper tropospheric and lower stratospheric conditions. Variations of temperature are the key determinant for the distribution of RHI, followed by variations of the water vapor mixing ratio. Multiple humidity modes, generated by mixing of different air masses, may contribute to the overall distribution of RHI, in particular below ice saturation. The fraction of air that is supersaturated with respect to ice is mainly determined by the distribution of temperature. The nucleation of ice in cirrus clouds determines the highest relative humdity that can be measured outside of cirrus clouds. While vertical air motion and ice microphysics determine the slope of the distributions of RHI, as shown in a separate study companion (Haag et al., 2003, clouds are not required to explain the main features of the distributions of RHI below the ice nucleation threshold.

Key words. Atmospheric composition and structure (pressure, density and temperature; troposphere – composition and chemistry; general or miscellaneous

Relationship between relative humidity and the dew point ...

African Journals Online (AJOL)

This research was aimed at determining the relationship between relative humidity and the dew point temperature in Benin City, Edo State, Nigeria. The dew point temperature was approximated from the measured air temperature and relative humidity with the aid of a currently self-designed weather monitoring system.

Clinker mineral hydration at reduced relative humidities

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede; Hansen, Per Freiesleben; Lachowski, Eric E.

1999-01-01

and experimental data are presented showing that C(3)A can hydrate at lower humidities than either C3S or C2S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C(3)A hydrates at low humidity, the characteristic hydration product is C(3)AH(6......Vapour phase hydration of purl cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both the oretical considerations...

Performance Evaluation of a Modular Design of Wind Tower with Wetted Surfaces

Directory of Open Access Journals (Sweden)

Sajad M.R. Khani

2017-06-01

Full Text Available Wind towers or wind catchers, as passive cooling systems, can provide natural ventilation in buildings located in hot, arid regions. These natural cooling systems can provide thermal comfort for the building inhabitants throughout the warm months. In this paper, a modular design of a wind tower is introduced. The design, called a modular wind tower with wetted surfaces, was investigated experimentally and analytically. To determine the performance of the wind tower, air temperature, relative humidity (RH and air velocity were measured at different points. Measurements were carried out when the wind speed was zero. The experimental results were compared with the analytical ones. The results illustrated that the modular wind tower can decrease the air temperature significantly and increase the relative humidity of airflow into the building. The average differences for air temperature and air relative humidity between ambient air and air exiting from the wind tower were approximately 10 °C and 40%, respectively. The main advantage of the proposed wind tower is that it is a modular design that can reduce the cost of wind tower construction.

High resolution vertical profiles of wind, temperature and humidity obtained by computer processing and digital filtering of radiosonde and radar tracking data from the ITCZ experiment of 1977

Science.gov (United States)

Danielson, E. F.; Hipskind, R. S.; Gaines, S. E.

1980-01-01

Results are presented from computer processing and digital filtering of radiosonde and radar tracking data obtained during the ITCZ experiment when coordinated measurements were taken daily over a 16 day period across the Panama Canal Zone. The temperature relative humidity and wind velocity profiles are discussed.

Effect of relative humidity on growth of sodium oxide aerosols

International Nuclear Information System (INIS)

Sundarajan, A.R.; Mitragotri, D.S.; Mukunda Rao, S.R.

1982-01-01

Behavior of aerosol resulting from sodium fires in a closed vessel is investigated and the changes in the particle size distribution of the aerosol due to coagulation and humidity have been studied. The initial mass concentration is in the range of 80 -- 500 mg/m 3 and the relative humidity is varied between 50 to 98%. The initial size of the released aerosol is found to be 0.9 μm. Equilibrium diameters of particles growing in humid air have been computed for various humidity levels using water activity of sodium hydroxide. Both theoretical and experimental results have yielded growth ratios of about 3 at about 95% relative humidity. It is recommended that the computer codes dealing with aerosol coagulation behavior in reactor containment should include an appropriate humidity-growth function. (author)

On the distribution of relative humidity in cirrus clouds

Directory of Open Access Journals (Sweden)

P. Spichtinger

2004-01-01

Full Text Available We have analysed relative humidity statistics from measurements in cirrus clouds taken unintentionally during the Measurement of OZone by Airbus In-service airCraft project (MOZAIC. The shapes of the in-cloud humidity distributions change from nearly symmetric in relatively warm cirrus (warmer than −40°C to considerably positively skew (i.e. towards high humidities in colder clouds. These results are in agreement to findings obtained recently from the INterhemispheric differences in Cirrus properties from Anthropogenic emissions (INCA campaign (Ovarlez et al., 2002. We interprete the temperature dependence of the shapes of the humidity distributions as an effect of the length of time a cirrus cloud needs from formation to a mature equilibrium stage, where the humidity is close to saturation. The duration of this transitional period increases with decreasing temperature. Hence cold cirrus clouds are more often met in the transitional stage than warm clouds.

Lower-tropospheric humidity: climatology, trends and the relation to the ITCZ

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Alexander Läderach

2013-07-01

Full Text Available The tropical region is an area of maximum humidity and serves as the major humidity source of the globe. Among other phenomena, it is governed by the so-called Inter-Tropical Convergence Zone (ITCZ which is commonly defined by converging low-level winds or enhanced precipitation. Given its importance as a humidity source, we investigate the humidity fields in the tropics in different reanalysis data sets, deduce the climatology and variability and assess the relationship to the ITCZ. Therefore, a new analysis method of the specific humidity distribution is introduced which allows detecting the location of the humidity maximum, the strength and the meridional extent. The results show that the humidity maximum in boreal summer is strongly shifted northward over the warm pool/Asia Monsoon area and the Gulf of Mexico. These shifts go along with a peak in the strength in both areas; however, the extent shrinks over the warm pool/Asia Monsoon area, whereas it is wider over the Gulf of Mexico. In winter, such connections between location, strength and extent are not found. Still, a peak in strength is again identified over the Gulf of Mexico in boreal winter. The variability of the three characteristics is dominated by inter-annual signals in both seasons. The results using ERA-interim data suggest a positive trend in the Gulf of Mexico/Atlantic region from 1979 to 2010, showing an increased northward shift in the recent years. Although the trend is only weakly confirmed by the results using MERRA reanalysis data, it is in phase with a trend in hurricane activity – a possible hint of the importance of the new method on hurricanes. Furthermore, the position of the maximum humidity coincides with one of the ITCZ in most areas. One exception is the western and central Pacific, where the area is dominated by the double ITCZ in boreal winter. Nevertheless, the new method enables us to gain more insight into the humidity distribution, its variability and

A Trial Intercomparison of Humidity Generators at Extremes of Range Using Relative Humidity Transmitters

Science.gov (United States)

Stevens, M.; Benyon, R.; Bell, S. A.; Vicente, T.

2008-10-01

In order to effectively implement the Mutual Recognition Arrangement (MRA) of the International Committee for Weights and Measures (CIPM), national metrology institutes (NMIs) are required to support their claims of calibration and measurement capability (CMC) with a quality system compliant with ISO/IEC 17025, and with suitable evidence of participation in key or supplementary comparisons. The CMC review process, both at regional and inter-regional levels, uses criteria that combine the provisions mentioned above, together with additional evidence demonstrating scientific and technical competence of the institutes. For dew-point temperatures, there are key comparisons in progress under the Consultative Committee for Thermometry (CCT) and under the European regional metrology organisation (EUROMET), together with information available on past regional supplementary comparisons. However, for relative humidity there are, to date, no such comparisons available to support CMC entries. This paper presents and discusses the results of a preliminary investigation of the use of relative humidity and temperature transmitters in order to determine their suitability for the intercomparison of standard humidity generators in support of CMC claims for the calibration of relative humidity instruments. The results of a recent bilateral comparison between 2 NMIs at the extremes of the range up to 98%rh at 70 °C, and down to 1%rh at -40 °C are reported. Specific precautions and recommendations on the use of the devices as transfer standards are presented.

Mycotoxin production in wheat grains by different Aspergilli in relation to different relative humidities and storage periods.

Science.gov (United States)

Atalla, Mohamed Mabrouk; Hassanein, Naziha Mohamed; El-Beih, Ahmed Atef; Youssef, Youssef Abdel-ghany

2003-02-01

Four different Aspergilli (Aspergillus oryzae, A. parasiticus, A. terreus and A. versicolor) were grown on wheat grains underdifferent degrees of relative humidity 14, 50, 74, 80 and 90%. Samples of wheat grains were taken monthly for a period of six months and examined for mycotoxin production. A. oryzae was found to produce aflatoxins B1, B2, zearalenone, DON and T-2 toxins under elevated degrees of humidity and prolonged periods of storage. A. parasiticus produced aflatoxins B1, G1, NIV, DON and T-2 toxins in high concentrations during a period of not more than three months storage at 14% relative humidity; at an increased level of relative humidity of 74% ochratoxin A, zearalenone and sterigmatocystin were also produced at high levels. The isolate was drastic in toxin production. A. terrus produced toxins at 14% relative humidity (aflatoxin G2 and DON) at levels much higher than any other prevalent degrees of humidity. A. versicolor is highly sensitive to relative humidity and grain moisture content It produced aflatoxins B1, G1, NIV and DON at a relative humidity of 50% and another toxins (aflatoxin G2, ochratoxins A, B and zearalenone) at 74%. The microorganism can be considered a trichothecene producer under suitable relative humidity.

High accuracy acoustic relative humidity measurement in duct flow with air.

Science.gov (United States)

van Schaik, Wilhelm; Grooten, Mart; Wernaart, Twan; van der Geld, Cees

2010-01-01

An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and relative humidity (RH) instantaneously, by applying two ultrasonic transducers and an array of four temperature sensors. Measurement ranges are: gas velocity of 0-12 m/s with an error of ± 0.13 m/s, temperature 0-100 °C with an error of ± 0.07 °C and relative humidity 0-100% with accuracy better than 2 % RH above 50 °C. Main advantage over conventional humidity sensors is the high sensitivity at high RH at temperatures exceeding 50 °C, with accuracy increasing with increasing temperature. The sensors are non-intrusive and resist highly humid environments.

Crystallization speed of salbutamol as a function of relative humidity and temperature.

Science.gov (United States)

Zellnitz, Sarah; Narygina, Olga; Resch, Christian; Schroettner, Hartmuth; Urbanetz, Nora Anne

2015-07-15

Spray dried salbutamol sulphate and salbutamol base particles are amorphous as a result of spray drying. As there is always the risk of recrystallization of amorphous material, the aim of this work is the evaluation of the temperature and humidity dependent recrystallization of spray dried salbutamol sulphate and base. Therefore in-situ Powder X-ray Diffraction (PXRD) studies of the crystallization process at various temperature (25 and 35 °C) and humidity (60%, 70%, 80%, 90% relative humidity) conditions were performed. It was shown that the crystallization speed of salbutamol sulphate and base is a non-linear function of both temperature and relative humidity. The higher the relative humidity the higher is the crystallization speed. At 60% relative humidity salbutamol base as well as salbutamol sulphate were found to be amorphous even after 12 h, however samples changed optically. At 70% and 90% RH recrystallization of salbutamol base is completed after 3 h and 30 min and recrystallization of salbutamol sulphate after 4h and 1h, respectively. Higher temperature (35 °C) also leads to increased crystallization speeds at all tested values of relative humidity. Copyright © 2015 Elsevier B.V. All rights reserved.

An Inexpensive, Stable, and Accurate Relative Humidity Measurement Method for Challenging Environments.

Science.gov (United States)

Zhang, Wei; Ma, Hong; Yang, Simon X

2016-03-18

In this research, an improved psychrometer is developed to solve practical issues arising in the relative humidity measurement of challenging drying environments for meat manufacturing in agricultural and agri-food industries. The design in this research focused on the structure of the improved psychrometer, signal conversion, and calculation methods. The experimental results showed the effect of varying psychrometer structure on relative humidity measurement accuracy. An industrial application to dry-cured meat products demonstrated the effective performance of the improved psychrometer being used as a relative humidity measurement sensor in meat-drying rooms. In a drying environment for meat manufacturing, the achieved measurement accuracy for relative humidity using the improved psychrometer was ±0.6%. The system test results showed that the improved psychrometer can provide reliable and long-term stable relative humidity measurements with high accuracy in the drying system of meat products.

High Accuracy Acoustic Relative Humidity Measurement inDuct Flow with Air

Directory of Open Access Journals (Sweden)

Cees van der Geld

2010-08-01

Full Text Available An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and relative humidity (RH instantaneously, by applying two ultrasonic transducers and an array of four temperature sensors. Measurement ranges are: gas velocity of 0–12 m/s with an error of ±0.13 m/s, temperature 0–100 °C with an error of ±0.07 °C and relative humidity 0–100% with accuracy better than 2 % RH above 50 °C. Main advantage over conventional humidity sensors is the high sensitivity at high RH at temperatures exceeding 50 °C, with accuracy increasing with increasing temperature. The sensors are non-intrusive and resist highly humid environments.

Coexistence of Dunes and Humid Conditions at Titan's Tropics

Science.gov (United States)

Radebaugh, Jani; Lorenz, R. D.; Lunine, J. I.; Kirk, R. L.; Ori, G. G.; Farr, T. G.; Malaska, M.; Le Gall, A.; Liu, Z. Y. C.; Encrenaz, P. J.; Paillou, P.; Hayes, A.; Lopes, R. M. C.; Turtle, E. P.; Wall, S. D.; Stofan, E. R.; Wood, C. A.; Cassini RADAR Team

2012-10-01

At Titan's equatorial latitudes there are tens of thousands of dunes, a landform typical of desert environments where sand does not become anchored by vegetation or fluids. Model climate simulations predict generally dry conditions at the equator and humid conditions near the poles of Titan, where lakes of methane/ethane are found. However, moderate relative methane humidity was observed at the Huygens landing site, recent rainfall was seen by Cassini ISS near the Belet Sand Sea, and a putative transient lake in Shangri-La was observed by Cassini VIMS, all of which indicate abundant fluids may be present, at least periodically, at Titan's equatorial latitudes. Terrestrial observations and studies demonstrate dunes can exist and migrate in conditions of high humidity. Active dunes are found in humid climates, indicating the movement of sand is not always prohibited by the presence of fluids. Sand mobility is related to precipitation, evaporation and wind speed and direction. If dune surfaces become wetted by rainfall or rising subsurface fluids, they can become immobilized. However, winds can act to dry the uppermost layers, freeing sands for saltation and enabling dune migration in wet conditions. Active dunes are found in tropical NE Brazil and NE Australia, where there are alternating dry and wet periods, a condition possible for Titan's tropics. Rising and falling water levels lead to the alteration of dune forms, mainly from being anchored by vegetation, but also from cementation by carbonates or clays. Studies of Titan's dunes, which could undergo anchoring of organic sediments by hydrocarbon fluids, could inform the relative strength of vegetation vs. cementation at humid dune regions on Earth. Furthermore, a comprehensive survey of dune morphologies near regions deemed low by SARTopo and stereo, where liquids may collect in wet conditions, could reveal if bodies of liquid have recently existed at Titan's tropics.

Calibration of Relative Humidity Sensors using a Dew Point Generator

OpenAIRE

Brooks, Milo

2010-01-01

A relative humidity sensor can be calibrated using a dew point generator to continuously supply an air stream of known constant humidity and a temperature chamber to control the dew point and ambient temperature.

The impact of relative humidity and atmospheric pressure on mortality in Guangzhou, China.

Science.gov (United States)

Ou, Chun Quan; Yang, Jun; Ou, Qiao Qun; Liu, Hua Zhang; Lin, Guo Zhen; Chen, Ping Yan; Qian, Jun; Guo, Yu Ming

2014-12-01

Although many studies have examined the effects of ambient temperatures on mortality, little evidence is on health impacts of atmospheric pressure and relative humidity. This study aimed to assess the impacts of atmospheric pressure and relative humidity on mortality in Guangzhou, China. This study included 213,737 registered deaths during 2003-2011 in Guangzhou, China. A quasi-Poisson regression with a distributed lag non-linear model was used to assess the effects of atmospheric pressure/relative humidity. We found significant effect of low atmospheric pressure/relative humidity on mortality. There was a 1.79% (95% confidence interval: 0.38%-3.22%) increase in non-accidental mortality and a 2.27% (0.07%-4.51%) increase in cardiovascular mortality comparing the 5th and 25th percentile of atmospheric pressure. A 3.97% (0.67%-7.39%) increase in cardiovascular mortality was also observed comparing the 5th and 25th percentile of relative humidity. Women were more vulnerable to decrease in atmospheric pressure and relative humidity than men. Age and education attainment were also potential effect modifiers. Furthermore, low atmospheric pressure and relative humidity increased temperature-related mortality. Both low atmospheric pressure and relative humidity are important risk factors of mortality. Our findings would be helpful to develop health risk assessment and climate policy interventions that would better protect vulnerable subgroups of the population. Copyright © 2014 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Particle backscatter and relative humidity measured across cirrus clouds and comparison with microphysical cirrus modelling

Directory of Open Access Journals (Sweden)

M. Brabec

2012-10-01

Full Text Available Advanced measurement and modelling techniques are employed to estimate the partitioning of atmospheric water between the gas phase and the condensed phase in and around cirrus clouds, and thus to identify in-cloud and out-of-cloud supersaturations with respect to ice. In November 2008 the newly developed balloon-borne backscatter sonde COBALD (Compact Optical Backscatter and AerosoL Detector was flown 14 times together with a CFH (Cryogenic Frost point Hygrometer from Lindenberg, Germany (52° N, 14° E. The case discussed here in detail shows two cirrus layers with in-cloud relative humidities with respect to ice between 50% and 130%. Global operational analysis data of ECMWF (roughly 1° × 1° horizontal and 1 km vertical resolution, 6-hourly stored fields fail to represent ice water contents and relative humidities. Conversely, regional COSMO-7 forecasts (6.6 km × 6.6 km, 5-min stored fields capture the measured humidities and cloud positions remarkably well. The main difference between ECMWF and COSMO data is the resolution of small-scale vertical features responsible for cirrus formation. Nevertheless, ice water contents in COSMO-7 are still off by factors 2–10, likely reflecting limitations in COSMO's ice phase bulk scheme. Significant improvements can be achieved by comprehensive size-resolved microphysical and optical modelling along backward trajectories based on COSMO-7 wind and temperature fields, which allow accurate computation of humidities, homogeneous ice nucleation, resulting ice particle size distributions and backscatter ratios at the COBALD wavelengths. However, only by superimposing small-scale temperature fluctuations, which remain unresolved by the numerical weather prediction models, can we obtain a satisfying agreement with the observations and reconcile the measured in-cloud non-equilibrium humidities with conventional ice cloud microphysics. Conversely, the model-data comparison provides no evidence that additional

Laboratory study of SO2 dry deposition on limestone and marble: Effects of humidity and surface variables

Science.gov (United States)

Spiker, E. C.; Hosker, R.P.; Weintraub, V.C.; Sherwood, S.I.

1995-01-01

The dry deposition of gaseous air pollutants on stone and other materials is influenced by atmospheric processes and the chemical characteristics of the deposited gas species and of the specific receptor material. Previous studies have shown that relative humidity, surface moisture, and acid buffering capability of the receptor surface are very important factors. To better quantify this behavior, a special recirculating wind tunnel/environmental chamber was constructed, in which wind speed, turbulence, air temperature, relative humidity, and concentrations of several pollutants (SO2, O3, nitrogen oxides) can be held constant. An airfoil sample holder holds up to eight stone samples (3.8 cm in diameter and 1 cm thick) in nearly identical exposure conditions. SO2 deposition on limestone was found to increase exponentially with increasing relative humidity (RH). Marble behaves similarly, but with a much lower deposition rate. Trends indicate there is little deposition below 20% RH on clean limestone and below 60% RH on clean marble. This large difference is due to the limestone's greater porosity, surface roughness, and effective surface area. These results indicate surface variables generally limit SO2 deposition below about 70% RH on limestone and below at least 95% RH on marble. Aerodynamic variables generally limit deposition at higher relative humidity or when the surface is wet.The dry deposition of gaseous air pollutants on stone and other materials is influenced by atmospheric processes and the chemical characteristics of the deposited gas species and of the specific receptor material. Previous studies have shown that relative humidity, surface moisture, and acid buffering capability of the receptor surface are very important factors. To better quantify this behavior, a special recirculating wind tunnel/environmental chamber was constructed, in which wind speed, turbulence, air temperature, relative humidity, and concentrations of several pollutants (SO2, O3

Temperature-dependent deliquescence relative humidities and water activities using humidity controlled thermogravimetric analysis with application to malonic acid.

Science.gov (United States)

Beyer, Keith D; Schroeder, Jason R; Kissinger, Jared A

2014-04-03

We utilize a new experimental technique, humidity-controlled thermogravimetric analysis (HTGA), to determine temperature-dependent deliquescence relative humidities (DRH) and to determine the equilibrium concentration of a solution at a given temperature and relative humidity. To that end, we have investigated the malonic acid/water system determining the DRH and concentration/RH relationship in the temperature range 303-278 K. Excellent agreement is found with literature values for the DRH of malonic acid as a function of temperature and for the concentration/RH relationship at several temperatures. Thus, we extend the DRH and concentration/RH relationship to a broader temperature range and are using the HTGA experiments to investigate other organic acids.

Statistical modeling of temperature, humidity and wind fields in the atmospheric boundary layer over the Siberian region

Science.gov (United States)

Lomakina, N. Ya.

2017-11-01

The work presents the results of the applied climatic division of the Siberian region into districts based on the methodology of objective classification of the atmospheric boundary layer climates by the "temperature-moisture-wind" complex realized with using the method of principal components and the special similarity criteria of average profiles and the eigen values of correlation matrices. On the territory of Siberia, it was identified 14 homogeneous regions for winter season and 10 regions were revealed for summer. The local statistical models were constructed for each region. These include vertical profiles of mean values, mean square deviations, and matrices of interlevel correlation of temperature, specific humidity, zonal and meridional wind velocity. The advantage of the obtained local statistical models over the regional models is shown.

Autogenous Deformation and Change of the Relative Humidity in Silica Fume-Modified Cement Paste

DEFF Research Database (Denmark)

Jensen, Ole mejlhede; Hansen, Per Freiesleben

1996-01-01

Even during sealed curing and at a constant temperature a hardening cement paste will deform and the relative humidity within its pores will lower. This autogenous deformation and autogenous relative humidity change may be so significant that the cement paste cracks if the deformation is restrained....... This article focuses on the influence of silica fume addition on autogenous deformation and autogenous relative humidity change. Continuous measurement of autogenous deformation and autogenous relative humidity change for more than 1 year and 1« years, respectively, was performed. The investigations show...... thatsilica fume addition markedly increases the autogenous shrinkage as well as the autogenous relative humidity change....

Effect of relative humidity on solar potential

International Nuclear Information System (INIS)

Soezen, Adnan; Arcaklioglu, Erol

2005-01-01

In this study, the effect of relative humidity on solar potential is investigated using artificial neural-networks. Two different models are used to train the neural networks. Meteorological and geographical data (latitude, longitude, altitude, month, mean sunshine-duration, and mean temperature) are used in the input layer of the network (Model 1). But, relative humidity values are added to one network in model (Model 2). In other words, the only difference between the models is relative humidity. New formulae based on meteorological and geographical data, have been developed to determine the solar energy potential in Turkey using the networks' weights for both models. Scaled conjugate gradient (SCG) and Levenberg-Marquardt (LM) learning algorithms and a logistic sigmoid transfer-function were used in the network. The best approach was obtained by the SCG algorithm with nine neurons for both models. Meteorological data for the four years, 2000-2003, for 18 cities (Artvin, Cesme, Bozkurt, Malkara, Florya, Tosya, Kizilcahamam, Yenisehir, Edremit, Gediz, Kangal, Solhan, Ergani, Selcuk, Milas, Seydisehir, Siverek and Kilis) spread over Turkey have been used as data in order to train the neural network. Solar radiation is in output layer. One month for each city was used as test data, and these months have not been used for training. The maximum mean absolute percentage errors (MAPEs) for Tosya are 2.770394% and 2.8597% for Models 1 and 2, respectively. The minimum MAPEs for Seydisehir are 1.055205% and 1.041% with R 2 (99.9862%, 99.9842%) for Models 1 and 2, respectively, in the SCG algorithm with nine neurons. The best value of R 2 for Models 1 and 2 are for Seydisehir. The minimum value of R 2 for Model 1 is 99.8855% for Tosya, and the value for Model 2 is 99.9001% for Yenisehir. Results show that the humidity has only a negligible effect upon the prediction of solar potential using artificial neural-networks

Roller compaction: Effect of relative humidity of lactose powder.

Science.gov (United States)

Omar, Chalak S; Dhenge, Ranjit M; Palzer, Stefan; Hounslow, Michael J; Salman, Agba D

2016-09-01

The effect of storage at different relative humidity conditions, for various types of lactose, on roller compaction behaviour was investigated. Three types of lactose were used in this study: anhydrous lactose (SuperTab21AN), spray dried lactose (SuperTab11SD) and α-lactose monohydrate 200M. These powders differ in their amorphous contents, due to different manufacturing processes. The powders were stored in a climatic chamber at different relative humidity values ranging from 10% to 80% RH. It was found that the roller compaction behaviour and ribbon properties were different for powders conditioned to different relative humidities. The amount of fines produced, which is undesirable in roller compaction, was found to be different at different relative humidity. The minimum amount of fines produced was found to be for powders conditioned at 20-40% RH. The maximum amount of fines was produced for powders conditioned at 80% RH. This was attributed to the decrease in powder flowability, as indicated by the flow function coefficient ffc and the angle of repose. Particle Image Velocimetry (PIV) was also applied to determine the velocity of primary particles during ribbon production, and it was found that the velocity of the powder during the roller compaction decreased with powders stored at high RH. This resulted in less powder being present in the compaction zone at the edges of the rollers, which resulted in ribbons with a smaller overall width. The relative humidity for the storage of powders has shown to have minimal effect on the ribbon tensile strength at low RH conditions (10-20%). The lowest tensile strength of ribbons produced from lactose 200M and SD was for powders conditioned at 80% RH, whereas, ribbons produced from lactose 21AN at the same condition of 80% RH showed the highest tensile strength. The storage RH range 20-40% was found to be an optimum condition for roll compacting three lactose powders, as it resulted in a minimum amount of fines in the

Relationship of the moisture content of Finnish wheat flour and relative humidity

Directory of Open Access Journals (Sweden)

Yu-Yen Linko

1968-01-01

Full Text Available Changes in the moisture content of Finnish commercial wheat flour stored at variable relative humidities, representing the conditions typical of flour storage in Finland, were investigated. It could be shown that flour of 15 % moisture at the time of packing tends to dry considerably during normal storage conditions. Owing to the hysteresis effect, the moisture content of once dried flour is not likely to reach detrimental levels during normal storage, even if the relative humidity would exceed the critical level of 75—80 % for short periods. Minimum warehouse relative humidity was observed during Januay, at which time flour moisture had decreased to 6.7 %. The equilibrium humidity for flour of 15 % original moisture content was found to be about 70 %.

CONTROLLING FACTORS OF POTENTIAL EVAPOTRANSPIRATION ABOVE GRASSLAND IN HUMID AND ARID AREA

Directory of Open Access Journals (Sweden)

. Yanto

2013-05-01

Full Text Available Potential evapotranspiration (PET is an importance process in water balance studies controlled by a number of meteorological factors such as temperature, wind speed, atmospheric pressure, solar radiation, vapor pressure gradient, relative humidity and biological factors such as vegetation type, canopy height and plant density that varied in time-scale and in spatial scale. Of all those variables, determining the most controlling factors of evapotranspiration in humid and arid area is of interest of this paper. Two sites representing humid and arid area i.e. Fermi Prairie site in Illinois and Audubon Research Ranch in Arizona respectively were investigated in this study.  The flux data employed in this study was acquired from Ameriflux Netwotk. Penmann-Monteith formula is employed in to estimate evapotranspiration rate in both sites. The result shows that the PET is in dependence on the considered meteorological factor such as shortwave radiation, vapor pressure, air temperature, wind speed, net radiation and vapor pressure deficit. It is also can be inferred from the analysis that PET is also strongly controlled by vegetation factors represented as stomatal resistance. Keywords: Potential evapotranspiration, Penmann-Monteith, humid, arid.

SIZE DISTRIBUTION OF SEA-SALT EMISSIONS AS A FUNCTION OF RELATIVE HUMIDITY

Science.gov (United States)

This note presents a straightforward method to correct sea-salt-emission particle-size distributions according to local relative humidity. The proposed method covers a wide range of relative humidity (0.45 to 0.99) and its derivation incorporates recent laboratory results on sea-...

Doppler Lidar Wind Value-Added Product

Energy Technology Data Exchange (ETDEWEB)

Newsom, R. K. [DOE ARM Climate Research Facility, Washington, DC (United States); Sivaraman, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Shippert, T. R. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. D. [DOE ARM Climate Research Facility, Washington, DC (United States)

2015-07-01

Wind speed and direction, together with pressure, temperature, and relative humidity, are the most fundamental atmospheric state parameters. Accurate measurement of these parameters is crucial for numerical weather prediction. Vertically resolved wind measurements in the atmospheric boundary layer are particularly important for modeling pollutant and aerosol transport. Raw data from a scanning coherent Doppler lidar system can be processed to generate accurate height-resolved measurements of wind speed and direction in the atmospheric boundary layer.

Retrieval of relative humidity from CSIR-NLC mobile LIDAR backscatter measurements

CSIR Research Space (South Africa)

Tesfaye, M

2009-09-01

Full Text Available data was collected over 23 hours. The above data sets were used to determine the retrieved relative humidity and compared with Irene (near to Pretoria) weather balloon humidity measurements. The results of the comparative study are presented...

Analysis of air temperature and relative humidity: study of microclimates

OpenAIRE

Elis Dener Lima Alves; Marcelo Sacardi Biudes

2012-01-01

Understanding the variability of climate elements in time and space is fundamental to the knowledge of the dynamics of microclimate. Thus, the objective was to analyze the variability of air temperature and relative humidity on the Cuiabá campus of the Federal University of Mato Grosso, and, through the clustering technique, to analyze the formation of groups to propose a zoning microclimate in the area study. To this end, collection data of air temperature and relative humidity at 15 points ...

A mathematical correlation between variations in solar radiation parameters. 2. Global radiation, air temperature and specific humidity

International Nuclear Information System (INIS)

Njau, E.C.

1988-06-01

We derive from first principles, an equation which expresses global radiation as a function of specific humidity and air temperature at screen height. The practical validity of this equation is tested by using humidity, air temperature and global radiation data from Tanzania. It is shown that global radiation values calculated on the basis of the derived equation agree with measured radiation values to within ± 8% as long as the prevalent (horizontal) winds are either calm or light. It is noted that the equation is equally valid at times of strong horizontal winds provided that the temperature and humidity measuring site is sufficiently shielded from the winds. This implies that meteorological stations that are (for some unavoidable reasons) unable to stock pyranometers can still procure reasonable estimates of local global radiation as long as they can, at least, stock the relatively cheaper barometers and wet- and dry-bulb psychrometers. (author). 12 refs, 1 fig., 4 tabs

EDITORIAL: Humidity sensors Humidity sensors

Science.gov (United States)

Regtien, Paul P. L.

2012-01-01

All matter is more or less hygroscopic. The moisture content varies with vapour concentration of the surrounding air and, as a consequence, most material properties change with humidity. Mechanical and thermal properties of many materials, such as the tensile strength of adhesives, stiffness of plastics, stoutness of building and packaging materials or the thermal resistivity of isolation materials, all decrease with increasing environmental humidity or cyclic humidity changes. The presence of water vapour may have a detrimental influence on many electrical constructions and systems exposed to humid air, from high-power systems to microcircuits. Water vapour penetrates through coatings, cable insulations and integrated-circuit packages, exerting a fatal influence on the performance of the enclosed systems. For these and many other applications, knowledge of the relationship between moisture content or humidity and material properties or system behaviour is indispensable. This requires hygrometers for process control or test and calibration chambers with high accuracy in the appropriate temperature and humidity range. Humidity measurement methods can roughly be categorized into four groups: water vapour removal (the mass before and after removal is measured); saturation (the air is brought to saturation and the `effort' to reach that state is measured); humidity-dependent parameters (measurement of properties of humid air with a known relation between a specific property and the vapour content, for instance the refractive index, electromagnetic spectrum and acoustic velocity); and absorption (based on the known relation between characteristic properties of non-hydrophobic materials and the amount of absorbed water from the gas to which these materials are exposed). The many basic principles to measure air humidity are described in, for instance, the extensive compilations by Wexler [1] and Sonntag [2]. Absorption-type hygrometers have small dimensions and can be

Bacterial pleomorphism and competition in a relative humidity gradient

NARCIS (Netherlands)

de Goffau, Marcus C.; Yang, Xiaomei; van Dijl, Jan Maarten; Harmsen, Hermie J. M.

The response of different bacterial species to reduced water availability was studied using a simple relative humidity gradient technique. Interestingly, distinct differences in morphology and growth patterns were observed between populations of the same species growing at different relative

Clinker mineral hydration at reduced relative humidities

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede

1998-01-01

This report deals with gas phase hydration of pure cement clinker minerals at reduced relative humidities. This is an important subject in relation to modern high performance concrete which may self-desiccate during hydration. In addition the subject has relevance to storage stability where...... prehydration may occur. In the report both theoretical considerations and experimental data are presented. It is suggested that the initiation of hydration during water vapour exposure is nucleation controlled....

Relative humidity measurements with thermocouple psychrometer and capacitance sensors

International Nuclear Information System (INIS)

Mao, Naihsien.

1991-01-01

The relative humidity is one of the important hydrological parameters affecting waste package performance. Water potential of a system is defined as the amount of work required to reversibly and isothermally move an infinitesimal quantity of water from a pool of pure water to that system at the same elevation. The thermocouple psychrometer, which acts as a wet-dry bulb instrument based on the Peltier effect, is used to measure water potential. The thermocouple psychrometer works only for relative humidity greater than 94 percent. Other sensors must be used for drier conditions. Hence, the author also uses a Vaisala Humicap, which measures the capacitance change due to relative humidity change. The operation range of the Humicap (Model HMP 135Y) is from 0 to 100 percent relative humidity and up to 160C (320F) in temperature. A psychrometer has three thermocouple junctions. Two copper-constantan junctions serve as reference temperature junctions and the constantan-chromel junction is the sensing junction. Current is passed through the thermocouple causing cooling of the sensing junction by the Peltier effect. When the temperature of the junction is below the dew point, water will condense upon the junction from the air. The Peltier current is discontinued and the thermocouple output is recorded as the temperature of the thermocouple returns to ambient. The temperature changes rapidly toward the ambient temperature until it reaches the wet bulb depression temperature. At this point, evaporation of the water from the junction produces a cooling effect upon the junction that offsets the heat absorbed from the ambient surroundings. This continues until the water is depleted and the thermocouple temperature returns to the ambient temperature (Briscoe, 1984). The datalogger starts to take data roughly at the wet bulb depression temperature

Temperature and relative humidity dependence of radiochromic film dosimeter response to gamma electron radiation

DEFF Research Database (Denmark)

McLaughlin, W.L.; Puhl, J.M.; Miller, A.

1995-01-01

on some earlier studies, their response functions have been reported to be dependent on the temperature and relative humidity during irradiation. The present study investigates differences in response over practical ranges of temperature, relative humidity, dose, and for different recent batches of films...... humidity) and should be calibrated under environmental conditions (temperature) at which they will be used routinely....

Short term change in relative humidity during the festival of Diwali in India

Science.gov (United States)

Ganguly, Nandita D.

2015-07-01

The changes in humidity levels during the Diwali festivities have been examined over a period of 13 years at three Indian metro cities: Ahmedabad, New Delhi and Kolkata. A small short term increase in relative humidity even in the absence of transport of humid air from Arabian Sea and Bay of Bengal has been observed. The relative humidity levels were found to be exceeding the ambient levels during night and lying below the ambient levels during morning hours, indicating an increase in the survival rates of viruses responsible for the transmission of viral infections, as well as triggering immune-mediated illnesses such as asthma during Diwali.

Integrated CMOS dew point sensors for relative humidity measurement

Science.gov (United States)

Savalli, Nicolo; Baglio, Salvatore; Castorina, Salvatore; Sacco, Vincenzo; Tringali, Cristina

2004-07-01

This work deals with the development of integrated relative humidity dew point sensors realized by adopting standard CMOS technology for applications in various fields. The proposed system is composed by a suspended plate that is cooled by exploiting integrated Peltier cells. The cold junctions of the cells have been spread over the plate surface to improve the homogeneity of the temperature distribution over its surface, where cooling will cause the water condensation. The temperature at which water drops occur, named dew point temperature, is a function of the air humidity. Measurement of such dew point temperature and the ambient temperature allows to know the relative humidity. The detection of water drops is achieved by adopting a capacitive sensing strategy realized by interdigited fixed combs, composed by the upper layer of the adopted process. Such a capacitive sensor, together with its conditioning circuit, drives a trigger that stops the cooling of the plate and enables the reading of the dew point temperature. Temperature measurements are achieved by means of suitably integrated thermocouples. The analytical model of the proposed system has been developed and has been used to design a prototype device and to estimate its performances. In such a prototype, the thermoelectric cooler is composed by 56 Peltier cells, made by metal 1/poly 1 junctions. The plate has a square shape with 200 μm side, and it is realized by exploiting the oxide layers. Starting from the ambient temperature a temperature variation of ΔT = 15 K can be reached in 10 ms thus allowing to measure a relative humidity greater than 40%.

Relative Humidity in the Tropopause Saturation Layer

Science.gov (United States)

Selkirk, H. B.; Schoeberl, M. R.; Pfister, L.; Thornberry, T. D.; Bui, T. V.

2017-12-01

The tropical tropopause separates two very different atmospheric regimes: the stable lower stratosphere where the air is both extremely dry and nearly always so, and a transition layer in the uppermost tropical troposphere, where humidity on average increases rapidly downward but can undergo substantial temporal fluctuations. The processes that control the humidity in this layer below the tropopause include convective detrainment (which can result in either a net hydration or dehydration), slow ascent, wave motions and advection. Together these determine the humidity of the air that eventually passes through the tropopause and into the stratosphere, and we refer to this layer as the tropopause saturation layer or TSL. We know from in situ water vapor observations such as Ticosonde's 12-year balloonsonde record at Costa Rica that layers of supersaturation are frequently observed in the TSL. While their frequency is greatest during the local rainy season from June through October, supersaturation is also observed in the boreal winter dry season when deep convection is well south of Costa Rica. In other words, local convection is not a necessary condition for the presence of supersaturation. Furthermore, there are indications from airborne measurements during the recent POSIDON campaign at Guam that if anything deep convection tends to `reset' the TSL locally to a state of just-saturation. Conversely, it may be that layers of supersaturation are the result of slow ascent. To explore these ideas we take Ticosonde water vapor observations from the TSL, stratify them on the basis of relative humidity and report on the differences in the the history of upstream convective influence between supersaturated parcels and those that are not.

NOS CO-OPS Meteorological Data, Relative Humidity, 6-Minute

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has Relative Humidity data from NOAA NOS Center for Operational Oceanographic Products and Services (CO-OPS). WARNING: These preliminary data have not...

Relative Humidity Sensing Properties Of Cu2O Doped ZnO Nanocomposite

International Nuclear Information System (INIS)

Pandey, N. K.; Tiwari, K.; Tripathi, A.; Roy, A.; Rai, A.; Awasthi, P.

2009-01-01

In this paper we report application of Cu 2 O doped ZnO composite prepared by solid state reaction route as humidity sensor. Pellet samples of ZnO-Cu 2 O nanocrystalline powders with 2, 5 and 10 weight% of Cu 2 O in ZnO have been prepared. Pellets have been annealed at temperatures of 200-500 deg. C and exposed to humidity. It is observed that as relative humidity increases, resistance of the pellet decreases for the humidity from 10% to 90%. Sample with 5% of Cu 2 O doped in ZnO and annealed at 500 deg. C shows best results with sensitivity of 1.50 MΩ/%RH. In this case the hysteresis is low and the reproducibility high, making it the suitable candidate for humidity sensing.

Effect of the irradiation temperature and relative humidity on PVG dosifilm

International Nuclear Information System (INIS)

Jia Haishun; Chen Wenxiu; Shen Yuxin

1999-01-01

The effect of environmental factors, such as irradiation temperature and relative humidity, on the PVG dosifilm irradiated by EB was tested. Experiments show that the temperature coefficient of irradiated PVG dosifilm was 0.008 deg. C -1 from 20 deg. C to 55 deg. C, and the humidity coefficient was 0.006 per r.h. (%) from r.h. 0% to 76%. The PVG dosifilm can be used as a routine dosimeter for dose measurement for low-energy EB processing. The absorbed dose values for various irradiation temperature and humidity can be corrected based on experimental data. (author)

Effects of relative humidity on banana fruit drop

NARCIS (Netherlands)

Saengpook, C.; Ketsa, S.; Doorn, van W.G.

2007-01-01

Commercial ripening of banana fruit occurs at high relative humidity (RH), which prevents browning of damaged skin areas. In experiments with ripening at high RH (94 ± 1%) the individual fruit (fingers) of `Sucrier¿ (Musa acuminata, AA Group) banana exhibited a high rate of drop. The falling off of

Diurnal flight behavior of Ichneumonoidea (Insecta: Hymenoptera) related to environmental factors in a tropical dry forest.

Science.gov (United States)

González-Moreno, A; Bordera, S; Leirana-Alcocer, J; Delfín-González, H

2012-06-01

The biology and behavior of insects are strongly influenced by environmental conditions such as temperature and precipitation. Because some of these factors present a within day variation, they may be causing variations on insect diurnal flight activity, but scant information exists on the issue. The aim of this work was to describe the patterns on diurnal variation of the abundance of Ichneumonoidea and their relation with relative humidity, temperature, light intensity, and wind speed. The study site was a tropical dry forest at Ría Lagartos Biosphere Reserve, Mexico; where correlations between environmental factors (relative humidity, temperature, light, and wind speed) and abundance of Ichneumonidae and Braconidae (Hymenoptera: Ichneumonoidea) were estimated. The best regression model for explaining abundance variation was selected using the second order Akaike Information Criterion. The optimum values of temperature, humidity, and light for flight activity of both families were also estimated. Ichneumonid and braconid abundances were significantly correlated to relative humidity, temperature, and light intensity; ichneumonid also showed significant correlations to wind speed. The second order Akaike Information Criterion suggests that in tropical dry conditions, relative humidity is more important that temperature for Ichneumonoidea diurnal activity. Ichneumonid wasps selected toward intermediate values of relative humidity, temperature and the lowest wind speeds; while Braconidae selected for low values of relative humidity. For light intensity, braconids presented a positive selection for moderately high values.

Morphological and Relative Humidity Sensing Properties of Pure ZnO Nanomaterial

Directory of Open Access Journals (Sweden)

N. K. Pandey

2010-11-01

Full Text Available In this paper we report the resistive type humidity sensing properties of pure ZnO nanomaterial prepared by solid-state reaction method. Pellets of pure ZnO nanocrystalline powder have been made with 10 weight % of glass powder at pressure of 260 MPa by hydraulic press machine for 3 hours. These pellets have been sintered at temperatures 200 °C - 500 °C in an electric muffle furnace for 3 hours at heating rate of 5°C/min. After sintering, these pellets have been exposed to humidity in a specially designed humidity chamber at room temperature. It has been observed that as relative humidity increases, resistance of the pellets decreases for entire range of humidity i.e. 10 % to 90 %. The sensing element of ZnO shows best results with sensitivity of 11.13 MΩ/%RH for the annealing temperature of 400 °C. This sensing element manifests lower hysteresis, less effect of aging and high reproducibility for annealing temperature 400 °C. SEM micrographs show that the sensing elements manifest porous structure with a network of pores that are expected to provide sites for humidity adsorption. The average grain size calculated from SEM micrograph is 236 nm. XRD pattern shows peaks of hexagonal zincite. As calculated from Scherer’s formula, the average crystalline size for this sensing element is 59.4 nm. For this sensing element, the values of activation energy from the Arrhenius plot is 0.041 eV for temperature range 200 °C - 400 °C and 0.393 eV for temperature range 400 °C - 500 °C. The adsorption of water molecules on the surface takes place via a dissociative chemisorption process leading to release of electrons. ZnO has electron vacancy. Hence, because of this reaction, the electrons are accumulated at the ZnO surface and consequently, the resistance of the sensing element decreases with increase in relative humidity.

Physiological and subjective responses to low relative humidity.

Science.gov (United States)

Sunwoo, Yujin; Chou, Chinmei; Takeshita, Junko; Murakami, Motoko; Tochihara, Yutaka

2006-01-01

In order to investigate the influence of low relative humidity, we measured saccharin clearance time (SCT), frequency of blinking, heart rate (HR), blood pressure, hydration state of skin, transepidermal water loss (TEWL), recovery sebum level and skin temperature as physiological responses. We asked subjects to judge thermal, dryness and comfort sensations as subjective responses using a rating scale. Sixteen non-smoking healthy male students were selected. The pre-room conditions were maintained at an air temperature (Ta) of 25 degrees C and a relative humidity (RH) of 50%. The test room conditions were adjusted to provide a Ta of 25 degrees C and RH levels of 10%, 30% and 50%.RH had no effect on the activity of the sebaceous gland and on cardiovascular reactions like blood pressure and HR. However, it was obvious that low RH affects SCT, the dryness of the ocular mucosa and the stratum corneum of the skin and causes a decrease in mean skin temperature. Under 30% RH, the eyes and skin become dry, and under 10% RH the nasal mucous membrane becomes dry as well as the eyes and skin, and the mean skin temperature decreases. These findings suggested that to avoid dryness of the eyes and skin, it is necessary to maintain an RH greater than 30%, and to avoid dryness of the nasal mucous membrane, it is necessary to maintain an RH greater than 10%. Subjects felt cold immediately after a change in RH while they had only a slight perception of dryness at the change of humidity.

Seasonal Variations of Indoor Microbial Exposures and Their Relation to Temperature, Relative Humidity, and Air Exchange Rate

DEFF Research Database (Denmark)

Frankel, Mika; Bekö, Gabriel; Timm, Michael

2012-01-01

with temperature, relative humidity, and air exchange rates in Danish homes. Airborne inhalable dust was sampled in five Danish homes throughout the four seasons of 1 year (indoors, n = 127; outdoors, n = 37). Measurements included culturable fungi and bacteria, endotoxin, N-acetyl-beta-d-glucosaminidase, total...... inflammatory potential, particles (0.75 to 15 μm), temperature, relative humidity, and air exchange rates. Significant seasonal variation was found for all indoor microbial exposures, excluding endotoxin. Indoor fungi peaked in summer (median, 235 CFU/m3) and were lowest in winter (median, 26 CFU/m3). Indoor...... of inhalable dust and number of particles. Temperature and air exchange rates were positively associated with fungi and N-acetyl-beta-d-glucosaminidase and negatively with bacteria and the total inflammatory potential. Although temperature, relative humidity, and air exchange rates were significantly...

The effect of relative humidity on germination of Sporangia of Phytophthora ramorum

Science.gov (United States)

Sporangia of three isolates of P. ramorum representing three different clonal lineages were subjected to relative humidity (RH) levels between 80 and 100% for exposure periods ranging from 1 to 24 h at 20°C in darkness. Airtight snap-lid plastic containers (21.5 x 14.5 x 5 cm) were used as humidity ...

Bond Strength of Resin Composite to Dentin with Different Adhesive Systems: Influence of Relative Humidity and Application Time.

Science.gov (United States)

Amsler, Fabienne; Peutzfeldt, Anne; Lussi, Adrian; Flury, Simon

2015-06-01

To investigate the influence of relative humidity and application time on bond strength to dentin of different classes of adhesive systems. A total of 360 extracted human molars were ground to mid-coronal dentin. The dentin specimens were treated with one of six adhesive systems (Syntac Classic, OptiBond FL, Clearfil SE Bond, AdheSE, Xeno Select, or Scotchbond Universal), and resin composite (Filtek Z250) was applied to the treated dentin surface under four experimental conditions (45% relative humidity/application time according to manufacturers' instructions; 45% relative humidity/reduced application time; 85% relative humidity/application time according to manufacturers' instructions; 85% relative humidity/reduced application time). After storage (37°C, 100% humidity, 24 h), shear bond strength (SBS) was measured and data analyzed with nonparametric ANOVA followed by Kruskal-Wallis tests and Mann-Whitney U-tests with Bonferroni-Holm correction for multiple testing (level of significance: α = 0.05). Increased relative humidity and reduced application time had no effect on SBS for Clearfil SE Bond and Scotchbond Universal (p = 1.00). For Syntac Classic, OptiBond FL, AdheSE, and Xeno Select there was no effect on SBS of reduced application time of the adhesive system (p ≥ 0.403). However, increased relative humidity significantly reduced SBS for Syntac Classic, OptiBond FL, and Xeno Select irrespective of application time (p ≤ 0.003), whereas for AdheSE, increased relative humidity significantly reduced SBS at recommended application time only (p = 0.002). Generally, increased relative humidity had a detrimental effect on SBS to dentin, but reduced application time had no effect.

Relative Humidity Sensor Based on No-Core Fiber Coated by Agarose-Gel Film

Directory of Open Access Journals (Sweden)

Wei Xu

2017-10-01

Full Text Available A relative humidity (RH sensor based on single-mode–no-core–single-mode fiber (SNCS structure is proposed and experimentally demonstrated. The agarose gel is coated on the no-core fiber (NCF as the cladding, and multimode interference (MMI occurs in the SNCS structure. The transmission spectrum of the sensor is modulated at different ambient relative humidities due to the tunable refractive index property of the agarose gel film. The relative humidity can be measured by the wavelength shift and intensity variation of the dip in the transmission spectra. The humidity response of the sensors, coated with different concentrations and coating numbers of the agarose solution, were experimentally investigated. The wavelength and intensity sensitivity is obtained as −149 pm/%RH and −0.075 dB/%RH in the range of 30% RH to 75% RH, respectively. The rise and fall time is tested to be 4.8 s and 7.1 s, respectively. The proposed sensor has a great potential in real-time RH monitoring.

Estimating relations between temperature, relative humidity as independed variables and selected water quality parameters in Lake Manzala, Egypt

Directory of Open Access Journals (Sweden)

Gehan A.H. Sallam

2018-03-01

Full Text Available In Egypt, Lake Manzala is the largest and the most productive lake of northern coastal lakes. In this study, the continuous measurements data of the Real Time Water Quality Monitoring stations in Lake Manzala were statistically analyzed to measure the regional and seasonal variations of the selected water quality parameters in relation to the change of air temperature and relative humidity. Simple formulas are elaborated using the DataFit software to predict the selected water quality parameters of the Lake including pH, Dissolved Oxygen (DO, Electrical Conductivity (EC, Total Dissolved Solids (TDS, Turbidity, and Chlorophyll as a function of air temperature, relative humidity and quantities and qualities of the drainage water that discharge into the lake. An empirical positive relation was found between air temperature and the relative humidity and pH, EC and TDS and negative relation with DO. There is no significant effect on the other two parameters of turbidity and chlorophyll.

Relation of temperature and humidity to the risk of recurrent gout attacks.

Science.gov (United States)

Neogi, Tuhina; Chen, Clara; Niu, Jingbo; Chaisson, Christine; Hunter, David J; Choi, Hyon; Zhang, Yuqing

2014-08-15

Gout attack risk may be affected by weather (e.g., because of volume depletion). We therefore examined the association of temperature and humidity with the risk of recurrent gout attacks by conducting an internet-based case-crossover study in the United States (in 2003-2010) among subjects with a diagnosis of gout who had 1 or more attacks during 1 year of follow-up. We examined the association of temperature and humidity over the prior 48 hours with the risk of gout attacks using a time-stratified approach and conditional logistic regression. Among 632 subjects with gout, there was a significant dose-response relationship between mean temperature in the prior 48 hours and the risk of subsequent gout attack (P = 0.01 for linear trend). Higher temperatures were associated with approximately 40% higher risk of gout attack compared with moderate temperatures. There was a reverse J-shaped relationship between mean relative humidity and the risk of gout attacks (P = 0.03 for quadratic trend). The combination of high temperature and low humidity had the greatest association (odds ratio = 2.04, 95% confidence interval: 1.26, 3.30) compared with moderate temperature and relative humidity. Thus, high ambient temperature and possibly extremes of humidity were associated with an increased risk of gout attack, despite the likelihood that individuals are often in climate-controlled indoor environments. © The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Experimental drying shrinkage of hardened cement pastes as a function of relative humidity

DEFF Research Database (Denmark)

Hansen, Kurt Kielsgaard; Baroghel, V.B.

1996-01-01

The results of an experimental study concerning drying shrinkage measured as a function of relative humidity on thin specimens of mature hardened cement pastes are presented. The results obtained at two laboratories are compared.......The results of an experimental study concerning drying shrinkage measured as a function of relative humidity on thin specimens of mature hardened cement pastes are presented. The results obtained at two laboratories are compared....

Tapered Fiber Coated with Hydroxyethyl Cellulose/Polyvinylidene Fluoride Composite for Relative Humidity Sensor

Directory of Open Access Journals (Sweden)

M. Z. Muhammad

2013-01-01

Full Text Available A simple relative humidity (RH sensor is demonstrated using a tapered fiber coated with hydroxyethyl cellulose/polyvinylidene fluoride (HEC/PVDF composite as a probe. This coating acts as an inner cladding whose refractive index decreases with the rise in humidity and thus allows more light to be transmitted in humid state. A difference of up to 0.89 dB of the transmitted optical power is observed when RH changes from 50% to 80% in case of the silica fiber probe. The proposed sensor has a sensitivity of about 0.0228 dB/%RH with a slope linearity of more than 99.91%. In case of the plastic optical fiber (POF probe, the output voltage of the sensor increases linearly with a sensitivity of 0.0231 mV/%RH and a linearity of more than 99.65% as the relative humidity increases from 55% to 80%.

Biases of the MET Temperature and Relative Humidity Sensor (HMP45) Report

Energy Technology Data Exchange (ETDEWEB)

Kyrouac, Jenni [Argonne National Lab. (ANL), Argonne, IL (United States); Theisen, Adam [Univ. of Oklahoma, Norman, OK (United States)

2017-06-30

The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility Data Quality (DQ) Office was alerted to a potential bias in the surface meteorological instrumentation (MET) temperature when compared with a nearby Mesonet station. This led to an investigation into this problem that was expanded to include many of the other extended facilities (EF) and both the temperature and relative humidity (RH) variables. For this study, the Mesonet was used as the standard reference due to results that showed an increased accuracy in high-humidity environments along with the fact that the Mesonet had previous documented a problem with the HMP45C sensors. Some differences between the sites were taken into account during the analysis: 1. ARM MET sensors were upgraded from an HMP35 to an HMP45 throughout 2007 2. Mesonet switched to aspirated shields in 2009 – To mitigate the differences between aspirated and non-aspirated measurements, data were only analyzed when the wind speed was higher than 3 m/s. This reduced the uncertainty for the non-aspirated measurements from 1.51 ºC to 0.4 ºC. 3. ARM MET is mounted 0.5m higher than the Mesonet station (2.0m versus 1.5m) – This is assumed to have a negligible effect on the differences. 4. Sites were not co-located – For some locations, the distances between sites were as much as 45 km. As part of the investigation into the differences, the Mesonet had reported that the HMP45 sensors had a low-temperature bias in high-humidity environments. This was verified at two different sites where the ARM measurements were compared with the Mesonet measurements. The Mesonet provided redundant temperature measurements from two different sensors at each site. These measurements compared fairly well, while the ARM sensor showed a bias overnight when the humidities were higher. After reviewing the yearly average differences in the data and analyzing the RH data during fog events when we assume it should be

Hydration behaviour of synthetic saponite at variable relative humidity

Indian Academy of Sciences (India)

Hydration behaviour of synthetic saponite was examined by X-ray powder diffraction simulation at various relative humidities (RH). The basal spacing of the Ca-saponite increased stepwise with increase in RH. The (00) reflections observed reflect single or dual hydration states of smectite. Quasi-rational, intermediate, or ...

Wind Farm Wake: The Horns Rev Photo Case

Directory of Open Access Journals (Sweden)

Pierre-Elouan Réthoré

2013-02-01

Full Text Available The aim of the paper is to examine the nowadays well-known wind farm wake photographs taken on 12 February 2008 at the offshore Horns Rev 1 wind farm. The meteorological conditions are described from observations from several satellite sensors quantifying clouds, surface wind vectors and sea surface temperature as well as ground-based information at and near the wind farm, including Supervisory Control and Data Acquisition (SCADA data. The SCADA data reveal that the case of fog formation occurred 12 February 2008 on the 10:10 UTC. The fog formation is due to very special atmospheric conditions where a layer of cold humid air above a warmer sea surface re-condensates to fog in the wake of the turbines. The process is fed by warm humid air up-drafted from below in the counter-rotating swirl generated by the clock-wise rotating rotors. The condensation appears to take place primarily in the wake regions with relatively high axial velocities and high turbulent kinetic energy. The wind speed is near cut-in and most turbines produce very little power. The rotational pattern of spiraling bands produces the large-scale structure of the wake fog.

Improvement of lithium chloride dew-point hygrometer for direct reading and controlling of relative humidity

Energy Technology Data Exchange (ETDEWEB)

Zhang, X.Z.; Chu, Y.

1986-01-01

The lithium chloride dew-point hygrometer has many advantages over other types of hygrometers. However, it only reads and controls the dew-point temperature of air instead of the relative humidity, which is more important in industry, agriculture, food storage, and hygiene. This paper describes a new hygrometer which is based on the same principle as the lithium chloride dew-point hygrometer, but it can read and control the relative humidity directly. The instrument is quick in response and the ranges of temperature and relative humidity are quite large. Its accuracy is normally within 3% RH and its precision is within 2% RH.

Sensitivity of honeybee hygroreceptors to slow humidity changes and temporal humidity variation detected in high resolution by mobile measurements.

Science.gov (United States)

Tichy, Harald; Kallina, Wolfgang

2014-01-01

The moist cell and the dry cell on the antenna of the male honeybee were exposed to humidities slowly rising and falling at rates between -1.5%/s and +1.5%/s and at varying amplitudes in the 10 to 90% humidity range. The two cells respond to these slow humidity oscillations with oscillations in impulse frequency which depend not only on instantaneous humidity but also on the rate with which humidity changes. The impulse frequency of each cell was plotted as a function of these two parameters and regression planes were fitted to the data points of single oscillation periods. The regression slopes, which estimate sensitivity, rose with the amplitude of humidity oscillations. During large-amplitude oscillations, moist and dry cell sensitivity for instantaneous humidity and its rate of change was high. During small-amplitude oscillations, their sensitivity for both parameters was low, less exactly reflecting humidity fluctuations. Nothing is known about the spatial and temporal humidity variations a honeybee may encounter when flying through natural environments. Microclimatic parameters (absolute humidity, temperature, wind speed) were measured from an automobile traveling through different landscapes of Lower Austria. Landscape type affected extremes and mean values of humidity. Differences between peaks and troughs of humidity fluctuations were generally smaller in open grassy fields or deciduous forests than in edge habitats or forest openings. Overall, fluctuation amplitudes were small. In this part of the stimulus range, hygroreceptor sensitivity is not optimal for encoding instantaneous humidity and the rate of humidity change. It seems that honeybee's hygroreceptors are specialized for detecting large-amplitude fluctuations that are relevant for a specific behavior, namely, maintaining a sufficiently stable state of water balance. The results suggest that optimal sensitivity of both hygroreceptors is shaped not only by humidity oscillation amplitudes but also

Influence of relative humidity on radiosensitivity of Aspergillus flavus Link. infecting cocoa beans

International Nuclear Information System (INIS)

Amoako-Atta, B.; Odamtten, G.T.; Appiah, V.

1981-01-01

The first part of this paper deals with the moisture sorption isotherms of dried cocoa beans under different relative humidities of 55, 65, 75, 85 or 95%. The second part evaluates the effects of relative humidity (RH), initial moisture content (m.c.) of cocoa beans, and different radiation exposure doses (0, 250, 350, 450, 500 or 550 krad) on Aspergillus flavus spore inoculated cocoa beans kept in fixed RH environmental chamber of 75 or 85% RH post-irradiation for forty days. The results discussed suggest that the m.c. of beans increased from an initial level of 6.4% to 7, 7.8 and 8.9% at 55, 65, and 75% respectively, after a storage period of 6-8 days. However, beans stored under 85% or 95% RH continued to absorb moisture from their respective environments indefinitely during the 64-day storage period. Furthermore, the ambient relative humidity to which the beans are subjected before or after irradiation significantly affect the radiosensitivity of toxigenic A. flavus; the differences in such radiosensitivity are influenced by either the available moisture or the initial m.c. of the beans to the inoculum. The authors conclude from their study that high environmental RH increased the radio-resistance of A. flavus spores making it difficult to establish a radiation decontamination level of practical value under a tropical environment with high ambient relative humidity. (author)

Effect of Temperature and Relative Humidity on the Growth of ...

African Journals Online (AJOL)

were used to determine the temperature effect on the growth of H. fulvum. Maximum growth of H. ... The fungus showed maximum growth at 92.5 and 100% relative humidity. .... recommended that fruits and vegetables should be stored at low ...

Fabrication of a capacitive relative humidity sensor using aluminum thin films deposited on etched printed circuit board

Directory of Open Access Journals (Sweden)

Lee Jacqueline Ann L.

2016-01-01

Full Text Available A capacitive humidity-sensing device was created by thermal evaporation of 99.999% aluminum. The substrate used for the coating was etched double-sided printed circuit board. The etched printed circuit board serves as the dielectric of the capacitor while the aluminum thin films deposited on either side serve as the plates of the capacitor. The capacitance was measured before and after exposure to humidity. The device was then calibrated by comparing the readings of capacitance with that of the relative humidity sensor of the Vernier LabQuest2. It was found that there is a linear relationship between the capacitance and relative humidity given by the equation C=1.418RH+29.139 where C is the capacitance and RH is the relative humidity. The surface of the aluminum films is porous and it is through these pores that water is adsorbed and capillary condensation occurs, thereby causing the capacitance to change upon exposure to humidity.

Diffusion coefficients for unattached decay products of thoron - dependence on ventilation and relative humidity

International Nuclear Information System (INIS)

Kotrappa, P.; Bhanti, D.P.; Raghunath, B.

1976-01-01

The results of a study of the diffusivity of unattached decay products of thoron with respect to air changes using a recently developed diffusion sampler are reported. The dependence of diffusivity of radon/thoron decay products on relative humidity has also been investigated by measurement of diffusion coefficients in an atmosphere where relative humidities varied from 5 to 90%. Results are shown tabulated. (U.K.)

Uncertainties in downscaled relative humidity for a semi-arid region ...

Indian Academy of Sciences (India)

variables are extracted from the (1) National Centers for Environmental Prediction ... and (2) simulations of the third generation Canadian Coupled Global Climate ... Ef, MAE and P. Cumulative distribution functions were prepared from the ... Climate change; downscaling; hydroclimatology; relative humidity; multi-step linear ...

Seasonal variations of indoor microbial exposures and their relation to temperature, relative humidity, and air exchange rate.

Science.gov (United States)

Frankel, Mika; Bekö, Gabriel; Timm, Michael; Gustavsen, Sine; Hansen, Erik Wind; Madsen, Anne Mette

2012-12-01

Indoor microbial exposure has been related to adverse pulmonary health effects. Exposure assessment is not standardized, and various factors may affect the measured exposure. The aim of this study was to investigate the seasonal variation of selected microbial exposures and their associations with temperature, relative humidity, and air exchange rates in Danish homes. Airborne inhalable dust was sampled in five Danish homes throughout the four seasons of 1 year (indoors, n = 127; outdoors, n = 37). Measurements included culturable fungi and bacteria, endotoxin, N-acetyl-beta-d-glucosaminidase, total inflammatory potential, particles (0.75 to 15 μm), temperature, relative humidity, and air exchange rates. Significant seasonal variation was found for all indoor microbial exposures, excluding endotoxin. Indoor fungi peaked in summer (median, 235 CFU/m(3)) and were lowest in winter (median, 26 CFU/m(3)). Indoor bacteria peaked in spring (median, 2,165 CFU/m(3)) and were lowest in summer (median, 240 CFU/m(3)). Concentrations of fungi were predominately higher outdoors than indoors, whereas bacteria, endotoxin, and inhalable dust concentrations were highest indoors. Bacteria and endotoxin correlated with the mass of inhalable dust and number of particles. Temperature and air exchange rates were positively associated with fungi and N-acetyl-beta-d-glucosaminidase and negatively with bacteria and the total inflammatory potential. Although temperature, relative humidity, and air exchange rates were significantly associated with several indoor microbial exposures, they could not fully explain the observed seasonal variations when tested in a mixed statistical model. In conclusion, the season significantly affects indoor microbial exposures, which are influenced by temperature, relative humidity, and air exchange rates.

Transfer Efficiency of Bacteria and Viruses from Porous and Nonporous Fomites to Fingers under Different Relative Humidity Conditions

Science.gov (United States)

Gerba, Charles P.; Tamimi, Akrum H.; Kitajima, Masaaki; Maxwell, Sheri L.; Rose, Joan B.

2013-01-01

Fomites can serve as routes of transmission for both enteric and respiratory pathogens. The present study examined the effect of low and high relative humidity on fomite-to-finger transfer efficiency of five model organisms from several common inanimate surfaces (fomites). Nine fomites representing porous and nonporous surfaces of different compositions were studied. Escherichia coli, Staphylococcus aureus, Bacillus thuringiensis, MS2 coliphage, and poliovirus 1 were placed on fomites in 10-μl drops and allowed to dry for 30 min under low (15% to 32%) or high (40% to 65%) relative humidity. Fomite-to-finger transfers were performed using 1.0 kg/cm2 of pressure for 10 s. Transfer efficiencies were greater under high relative humidity for both porous and nonporous surfaces. Most organisms on average had greater transfer efficiencies under high relative humidity than under low relative humidity. Nonporous surfaces had a greater transfer efficiency (up to 57%) than porous surfaces (humidity, as well as under high relative humidity (nonporous, up to 79.5%; porous, <13.4%). Transfer efficiency also varied with fomite material and organism type. The data generated can be used in quantitative microbial risk assessment models to assess the risk of infection from fomite-transmitted human pathogens and the relative levels of exposure to different types of fomites and microorganisms. PMID:23851098

Effect of relative humidity on migration of BP from paperboard into a food simulant

DEFF Research Database (Denmark)

Barnkob, Line Lundbæk; Petersen, Jens Højslev

In the scientific literature it is obligatory to control and report the test time and temperature applied when testing migration but it is not current practice to either control or report the relative humidity (RH).......In the scientific literature it is obligatory to control and report the test time and temperature applied when testing migration but it is not current practice to either control or report the relative humidity (RH)....

A method for high accuracy determination of equilibrium relative humidity

DEFF Research Database (Denmark)

Jensen, O.M.

2012-01-01

This paper treats a new method for measuring equilibrium relative humidity and equilibrium dew-point temperature of a material sample. The developed measuring device is described – a Dew-point Meter – which by means of so-called Dynamic Dew-point Analysis permits quick and very accurate...

Statistical analysis of the effects of relative humidity and temperature ...

African Journals Online (AJOL)

Meteorological data from the Department of Satellite Application Facility on Climate Monitoring (CMSAF), DWD Germany have been used to study and investigate the effect of relative humidity and temperature on refractivity in twenty six locations grouped into for climatic regions aloft Nigeria (Coastal, Guinea savannah, ...

Wind forces and related saltation transport

NARCIS (Netherlands)

Leenders, J.K.; van Boxel, J.H.; Sterk, G.

2005-01-01

The effect of several wind characteristics on sand transport was studied in three experiments in north Burkina Faso, West Africa. The first experiment is used to analyse the relation between wind speed and shear stress fluctuations across height. The second experiment is used to study the relation

Effect of the temperature and relative humidity in dosemeters used for personnel monitoring

International Nuclear Information System (INIS)

Antonio Filho, J.

1982-12-01

The systematics of the combined effect of temperature and humidity on photographic dosimeters of the type Agfa-Gevaert, Kodak type II, III and the thermoluminescent dosimeters LiF:Mg,Ti (TLD-100, Harshaw), D-CaSO 4 :Dy-0,4 (Teledyne), e CaSO 4 :Dy+NaCl (IPEN), used in personal monitoring in Brazil was investigated, in the temperature range of 20 0 C to 50 0 C and relative humidity of 65% to 95%, in order to determine the best manner of utilization of these detectors in Brazilian climatic conditions. The dosimeters were studied in different forms of packing-sheet such as aluminezed paper and polyethylene. For the determination of the systematics, the dosimeters were irradiated in three conditions: before, during and after of storage in climatic chambers to a maximum period of 60 days. It was found that the dosimetric filmes and thermoluminescent dosimeter CaSO 4 :Dy+NaCl without protection, presented a high dependence to temperature and humidity, and when protected presented good results. Therefore, the best manner of utilization of these monitors in environments with relative humidity and temperature greater them 75% and 30 0 C respectively, is achieved with the protection of aluminized paper. The LiF:Mg,Ti and D+CaSO 4 :Dy-0,4 dosimeters can be utilized in their original form because they presented low dependence with humidity and temperature in the range studied. (Author) [pt

Engineering handbook on the atmospheric environmental guidelines for use in wind turbine generator development

Science.gov (United States)

Frost, W.; Long, B. H.; Turner, R. E.

1978-01-01

The guidelines are given in the form of design criteria relative to wind speed, wind shear, turbulence, wind direction, ice and snow loading, and other climatological parameters which include rain, hail, thermal effects, abrasive and corrosive effects, and humidity. This report is a presentation of design criteria in an engineering format which can be directly input to wind turbine generator design computations. Guidelines are also provided for developing specialized wind turbine generators or for designing wind turbine generators which are to be used in a special region of the United States.

Pressure and Relative Humidity Measurement Devices for Mars 2020 Rover

Science.gov (United States)

Hieta, M.; Genzer, M.; Nikkanen, T.; Haukka, H.; Harri, A.-M.; Polkko, J.; Rodriguez-Manfredi, J. A.

2017-09-01

One of the scientific payloads onboard the NASA Mars 2020 rover mission is Mars Environmental Dynamic Analyzer (MEDA): a set of environmental sensors for Mars surface weather measurements. Finnish Meteorological Institute (FMI) provides a pressure measurement device (MEDA PS) and a relative humidity measurement device (MEDA HS) for MEDA.

Diffusion through Pig Gastric Mucin: Effect of Relative Humidity.

Directory of Open Access Journals (Sweden)

Anna Runnsjö

Full Text Available Mucus covers the epithelium found in all intestinal tracts, where it serves as an important protecting barrier, and pharmaceutical drugs administrated by the oral, rectal, vaginal, ocular, or nasal route need to penetrate the mucus in order to reach their targets. Furthermore, the diffusion in mucus as well as the viscosity of mucus in the eyes, nose and throat can change depending on the relative humidity of the surrounding air. In this study we have investigated how diffusion through gels of mucin, the main protein in mucus, is affected by changes in ambient relative humidity (i.e. water activity. Already a small decrease in water activity was found to give rise to a significant decrease in penetration rate through the mucin gel of the antibacterial drug metronidazole. We also show that a decrease in water activity leads to decreased diffusion rate in the mucin gel for the fluorophore fluorescein. This study shows that it is possible to alter transport rates of molecules through mucus by changing the water activity in the gel. It furthermore illustrates the importance of considering effects of the water activity in the mucosa during development of potential pharmaceuticals.

Measurement of Temperature and Relative Humidity with Polymer Optical Fiber Sensors Based on the Induced Stress-Optic Effect

Science.gov (United States)

Pontes, Maria José

2018-01-01

This paper presents a system capable of measuring temperature and relative humidity with polymer optical fiber (POF) sensors. The sensors are based on variations of the Young’s and shear moduli of the POF with variations in temperature and relative humidity. The system comprises two POFs, each with a predefined torsion stress that resulted in a variation in the fiber refractive index due to the stress-optic effect. Because there is a correlation between stress and material properties, the variation in temperature and humidity causes a variation in the fiber’s stress, which leads to variations in the fiber refractive index. Only two photodiodes comprise the sensor interrogation, resulting in a simple and low-cost system capable of measuring humidity in the range of 5–97% and temperature in the range of 21–46 °C. The root mean squared errors (RMSEs) between the proposed sensors and the reference were 1.12 °C and 1.36% for the measurements of temperature and relative humidity, respectively. In addition, fiber etching resulted in a sensor with a 2 s response time for a relative humidity variation of 10%, which is one of the lowest recorded response times for intrinsic POF humidity sensors. PMID:29558387

Using Relative Humidity Forecasts to Manage Meningitis in the Sahel

Science.gov (United States)

Pandya, R. E.; Adams-Forgor, A.; Akweogno, P.; Awine, T.; Dalaba, M.; Dukic, V.; Dumont, A.; Hayden, M.; Hodgson, A.; Hopson, T. M.; Hugonnet, S.; Yoksas, T. C.

2012-12-01

Meningitis epidemics in the Sahel occur quasi-regularly and with devastating impact. In 2008, for example, eighty-eight thousand people contracted meningitis and over five thousand died. Until very recently, the protection provided by the only available vaccine was so limited and short-lived that the only practical strategy for vaccination was reactive: waiting until an epidemic occurred in the region and then vaccinating in that region to prevent the epidemic's further growth. Even with that strategy, there were still times when demand outpaced available vaccine. While a new vaccine has recently been developed that is effective and inexpensive enough to be used more broadly and proactively, it is only effective against the strain of bacteria that causes the most common kind of bacterial meningitis. As a result, there will likely be continued need for reactive vaccination strategies. It is widely known that meningitis epidemics in the Sahel occur only in the dry season. Our project investigated this relationship, and several independent lines of evidence demonstrate a robust relationship between the onset of the rainy season, as marked by weekly average relative humidity above 40%, and the end of meningitis epidemics. These lines of evidence include statistical analysis of two years of weekly meningitis and weather data across the Sahel, cross-correlation of ten years of meningitis and weather data in the Upper East region of northern Ghana, and high-resolution weather simulations of past meningitis seasons to interpolate available weather data. We also adapted two techniques that have been successfully used in public health studies: generalized additive models, which have been used to relate air quality and health, and a linearized version of the compartmental epidemics model that has been used to understand MRSA. Based on these multiple lines of evidence, average weekly relative humidity forecast two weeks in advance appears consistently and strongly related to

Why alite stops hydrating below 80% relative humidity

International Nuclear Information System (INIS)

Flatt, Robert J.; Scherer, George W.; Bullard, Jeffrey W.

2011-01-01

It has been observed that the hydration of cement paste stops when the relative humidity drops below about 80%. A thermodynamic analysis shows that the capillary pressure exerted at that RH shifts the solubility of tricalcium silicate, so that it is in equilibrium with water. This is a reflection of the chemical shrinkage in this system: according to Le Chatelier's principle, since the volume of the products is less than that of the reactants, a negative (capillary) pressure opposes the reaction.

Nacre-like hybrid films: Structure, properties, and the effect of relative humidity.

Science.gov (United States)

Abba, Mohammed T; Hunger, Philipp M; Kalidindi, Surya R; Wegst, Ulrike G K

2015-03-01

Functional materials often are hybrids composed of biopolymers and mineral constituents. The arrangement and interactions of the constituents frequently lead to hierarchical structures with exceptional mechanical properties and multifunctionality. In this study, hybrid thin films with a nacre-like brick-and-mortar microstructure were fabricated in a straightforward and reproducible manner through manual shear casting using the biopolymer chitosan as the matrix material (mortar) and alumina platelets as the reinforcing particles (bricks). The ratio of inorganic to organic content was varied from 0% to 15% and the relative humidities from 36% to 75% to determine their effects on the mechanical properties. It was found that increasing the volume fraction of alumina from 0% to 15% results in a twofold increase in the modulus of the film, but decreases the tensile strength by up to 30%, when the volume fraction of alumina is higher than 5%. Additionally, this study quantifies and illustrates the critical role of the relative humidity on the mechanical properties of the hybrid film. Increasing the relative humidity from 36% to 75% decreases the modulus and strength by about 45% and triples the strain at failure. These results suggest that complex hybrid materials can be manufactured and tailor made for specific applications or environmental conditions. Copyright © 2015. Published by Elsevier Ltd.

Effect of varying relative humidity on the rancidity of cashew ...

African Journals Online (AJOL)

Post harvest deterioration by microbes due to improper storage condition is considered to be the major cause of spoilage and rancidity of most oil-bearing seeds like cashew nuts through lipolytic action of lipase enzyme. Roasted cashew nuts were subjected to four different storage conditions with different relative humidity ...

Influence of relative humidity on tensile and compressive creep of ...

African Journals Online (AJOL)

This paper presents an experimental study on the influence of ambient relative humidity on tensile creep of plain concrete amended with Ground Granulated Blast - furnace Slag and compares it with its influence on compressive creep. Tensile and compressive creep tests were carried out on concrete specimens of 34.49 ...

Atmospheric air density analysis with Meteo-40S wind monitoring system

Directory of Open Access Journals (Sweden)

Zahariea Dănuţ

2017-01-01

Full Text Available In order to estimate the wind potential of wind turbine sites, the wind resource maps can be used for mean annual wind speed, wind speed frequency distribution and mean annual wind power density determination. The general evaluation of the wind resource and the wind turbine ratings are based on the standard air density measured at sea level and at 15°C, ρs=1.225 kg/m3. Based on the experimental data obtained for a continental climate specific location, this study will present the relative error between the standard air density and the density of the dry and the moist air. Considering a cold day, for example on Friday 10th February 2017, on 1-second measurement rate and 10-minute measuring interval starting at 16:20, the mean relative errors obtained are 10.4145% for dry air, and 10.3634% for moist air. Based on these results, a correction for temperature, atmospheric air pressure and relative humidity should be always considered for wind resource assessment, as well as for the predicting the wind turbines performance.

models of hourly dry bulb temperature and relative humidity of key

African Journals Online (AJOL)

user

3: Worst cases of MFE for Dry bulb temperature and Relative humidity. Fig. 4: Best cases of ... the Second Joint International Conference of. University of Ilorin, Ilorin, Nigeria and University ... Erbs, D. G., “Models and Applications for Weather.

A vantage from space can detect earlier drought onset: an approach using relative humidity.

Science.gov (United States)

Farahmand, Alireza; AghaKouchak, Amir; Teixeira, Joao

2015-02-25

Each year, droughts cause significant economic and agricultural losses across the world. The early warning and onset detection of drought is of particular importance for effective agriculture and water resource management. Previous studies show that the Standard Precipitation Index (SPI), a measure of precipitation deficit, detects drought onset earlier than other indicators. Here we show that satellite-based near surface air relative humidity data can further improve drought onset detection and early warning. This paper introduces the Standardized Relative Humidity Index (SRHI) based on the NASA Atmospheric Infrared Sounder (AIRS) observations. The results indicate that the SRHI typically detects the drought onset earlier than the SPI. While the AIRS mission was not originally designed for drought monitoring, we show that its relative humidity data offers a new and unique avenue for drought monitoring and early warning. We conclude that the early warning aspects of SRHI may have merit for integration into current drought monitoring systems.

Do Wind Turbines Affect Weather Conditions?: A Case Study in Indiana

Directory of Open Access Journals (Sweden)

Meghan F. Henschen

2011-01-01

Full Text Available Wind turbines are becoming increasingly widespread in the United States as the world looks for cleaner sources of energy. Scientists, policymakers, and citizens have strong opinions regarding the positive and negative effects of wind energy projects, and there is a great deal of misinformation about wind energy circulating on the Web and other media sources. The purpose of this study is to gain a better understanding of how the rotation of hundreds of turbines can influence local weather conditions within a wind farm and in the surrounding areas. This experiment measures temperature, atmospheric pressure, wind speed, wind direction, relative humidity, and evaporation with five weather instruments at Meadow Lake Wind Farm located in White, Jasper, and Benton Counties, Indiana, from November 4 through November 18, 2010. The data show that as wind passes throughout the wind farm, the air warms during the overnight and early morning hours and cools during daytime hours. Observed lower humidity rates and higher evaporation rates downwind also demonstrate that the air dries out as it travels through the wind farm. Further research over multiple seasons is necessary to examine the effects of warmer nighttime temperatures and drier conditions progressively downwind of the installation. Nevertheless, wind turbines did not negatively affect local weather patterns in our small-scale research and may actually prevent frost, which could have important positive implications for farmers by potentially prolonging the growing season.

In-situ Air Temperature and Relative Humidity in Greenbelt, MD, 2013-2015

Data.gov (United States)

National Aeronautics and Space Administration — This data set describes the temperature and relative humidity at 12 locations around Goddard Space Flight Center in Greenbelt MD at 15 minute intervals between...

High accuracy acoustic relative humidity measurement in duct flow with air

NARCIS (Netherlands)

Schaik, van W.; Grooten, M.H.M.; Wernaart, T.; Geld, van der C.W.M.

2010-01-01

An acoustic relative humidity sensor for air-steam mixtures in duct flow is designed and tested. Theory, construction, calibration, considerations on dynamic response and results are presented. The measurement device is capable of measuring line averaged values of gas velocity, temperature and

Modeling of humidity-related reliability in enclosures with electronics

DEFF Research Database (Denmark)

Hygum, Morten Arnfeldt; Popok, Vladimir

2015-01-01

Reliability of electronics that operate outdoor is strongly affected by environmental factors such as temperature and humidity. Fluctuations of these parameters can lead to water condensation inside enclosures. Therefore, modelling of humidity distribution in a container with air and freely exposed...

An effect of humid climate on micro structure and chemical component of natural composite (Boehmeria nivea-Albizia falcata based wind turbine blade

Directory of Open Access Journals (Sweden)

Sudarsono S.

2018-01-01

Full Text Available In this work, wind turbine blade NACA 4415 is fabricated from natural composite of Boehmeria nivea and Albizia falcate. The composite fabrication method used is hand lay up method. The aim of the work is to investigate an effect of humid climate of coastal area on micro structure and chemical composition of composite material of the blade. The wind turbine is tested at Pantai Baru, Bantul, Yogyakarta for 5.5 months. The micro structure scanning is performed with Scanning Electron Microscope (SEM and material component is measured with Energy Dispersive X-ray spectrometer (EDS. The samples are tested before and after the use within 5.5 month at the location. The results show that composite material inexperienced interface degradation and insignificant change of micro structure. From EDS test, it is observed that Na filtration reduces C and increases O in composite material after 5.5 months.

An effect of humid climate on micro structure and chemical component of natural composite (Boehmeria nivea-Albizia falcata) based wind turbine blade

Science.gov (United States)

Sudarsono, S.; Purwanto; Sudarsono, Johny W.

2018-02-01

In this work, wind turbine blade NACA 4415 is fabricated from natural composite of Boehmeria nivea and Albizia falcate. The composite fabrication method used is hand lay up method. The aim of the work is to investigate an effect of humid climate of coastal area on micro structure and chemical composition of composite material of the blade. The wind turbine is tested at Pantai Baru, Bantul, Yogyakarta for 5.5 months. The micro structure scanning is performed with Scanning Electron Microscope (SEM) and material component is measured with Energy Dispersive X-ray spectrometer (EDS). The samples are tested before and after the use within 5.5 month at the location. The results show that composite material inexperienced interface degradation and insignificant change of micro structure. From EDS test, it is observed that Na filtration reduces C and increases O in composite material after 5.5 months.

Effect of relative humidity on the tribological properties of hydrogenated diamond-like carbon films in a nitrogen environment

International Nuclear Information System (INIS)

Li Hongxuan; Xu Tao; Wang Chengbing; Chen Jianmin; Zhou Huidi; Liu Huiwen

2005-01-01

Hydrogenated diamond-like carbon (DLC) films were deposited on Si (100) wafers by a plasma enhanced chemical vapour deposition technique using CH 4 plus Ar as the feedstock. The friction and wear properties of the resulting films under different relative humidities, ranging from 5% to 100%, in a nitrogen environment, were measured using a ball-on-disc tribometer, with Si 3 N 4 balls as the counterparts. The friction surfaces of the films and Si 3 N 4 balls were observed on a scanning electron microscope, and investigated by x-ray photoelectron spectroscopy. The results showed that the friction coefficient increased continuously from 0.025 to 0.09 with increase in relative humidity from 5% to 100%, while the wear rate of the films sharply decreased and reached a minimum at a relative humidity of 40%, then it increased with further increase of the relative humidity. The interruption of the transferred carbon-rich layer on the Si 3 N 4 ball, and the friction-induced oxidation of the films at higher relative humidity were proposed as the main reasons for the increase in the friction coefficient. Moreover, the oxidation and hydrolysis of the Si 3 N 4 ball at higher relative humidity, leading to the formation of a tribochemical film, which mainly consists of silica gel, on the friction surface, are also thought to influence the friction and wear behaviour of the hydrogenated DLC films

Dependence of alpha radionuclide diffusion and deposition on relative air humidity

International Nuclear Information System (INIS)

Danis, A.; Ciubotariu, M.; Oncescu, M.; Mocsy, I.; Tomulescu, V.

2000-01-01

The diffusion and deposition of the gaseous and solid alpha radionuclides/aerosols depend strongly on the relative air humidity. This dependence gets a great significance in the case of radon and their genetically related alpha radionuclides monitoring in the dwelling and working places for radioprotection purposes, particularly in establishing the equilibrium factor. For the gaseous and solid alpha radionuclides genetically related, Rn-222 and its solid alpha descendants including their aerosols obtained by radionuclide attachments to different particles present in air, the vertical gradient of volume concentrations was experimentally determined. The experiments were performed in: an airtight tubular laboratory chamber, a house cellar (Cluj-Napoca) and the entrance gallery of an abandoned mine (Avram Iancu, Bihor), in which the relative humidity was ranging from 65% up to 96%. For the laboratory chamber, these radionuclides were generated by a calibrated Ra-226 source, prepared at the Radionuclide Production Centre, IPNE-HH, Bucharest. The source was included into an air tight device with a well known volume and it was used only after 40 days, when the Ra-226 and its alpha descendants were under radioactive equilibrium. For the diffusion/deposition studies, this source was coupled with the airtight laboratory chamber. In the mine gallery and house cellar, the radon and its descendants were naturally and continuously generated by radium sources in soil and building materials. The alpha volume concentration determinations required the use of a very accurate and sensitive alpha measurement method. These requirements were met by the alpha track method. This method was used by us in the following conditions: the CR-39 plastic track detector (Page, England) for the detection of the alpha particles and the optical microscopy for the study of alpha tracks (Wild stereomicroscope M7S and a Karl Zeiss Jena binocular microscope). The volume concentrations of radon and the

Quantitative Ethylene Measurements with MOx Chemiresistive Sensors at Different Relative Air Humidities

Directory of Open Access Journals (Sweden)

Matic Krivec

2015-11-01

Full Text Available The sensitivity of two commercial metal oxide (MOx sensors to ethylene is tested at different relative humidities. One sensor (MiCS-5914 is based on tungsten oxide, the other (MQ-3 on tin oxide. Both sensors were found to be sensitive to ethylene concentrations down to 10 ppm. Both sensors have significant response times; however, the tungsten sensor is the faster one. Sensor models are developed that predict the concentration of ethylene given the sensor output and the relative humidity. The MQ-3 sensor model achieves an accuracy of ±9.2 ppm and the MiCS-5914 sensor model predicts concentration to ±7.0 ppm. Both sensors are more accurate for concentrations below 50 ppm, achieving ±6.7 ppm (MQ-3 and 5.7 ppm (MiCS-5914.

Neutron diffraction for studying the influence of the relative humidity on the carbonation process of cement pastes

International Nuclear Information System (INIS)

Galan, I; Andrade, C; Castellote, M; Rebolledo, N; Sanchez, J; Toro, L; Puente, I; Campo, J; Fabelo, O

2011-01-01

The effect of humidity on hydrated cement carbonation has been studied by means of in-situ neutron diffraction measurements. The evolution of the main crystalline phases in the bulk of the sample, portlandite and calcite, has been monitored during the process. Data obtained from neutron diffraction allow the quantification of the phases involved. The results highlight the great influence of humidity on carbonation. At very low humidity there are almost no changes. Between 53 and 75% relative humidity, portlandite decrease and calcite increase data can be fitted to exponential decay functions. At very high humidity portlandite remains nearly constant while calcite increases slightly with time, almost linearly.

The relative influence of body characteristics on humid heat stress response

NARCIS (Netherlands)

Havenith, G.; Luttikholt, V. G.; Vrijkotte, T. G.

1995-01-01

The present study was designed to determine the relative importance of individual characteristics such as maximal oxygen uptake (VO2max), adiposity, DuBois body surface area (AD), surface to mass ratio (AD: mass) and body mass, for the individual's reaction to humid heat stress. For this purpose 27

Health Effects Related to Wind Turbine Noise Exposure

DEFF Research Database (Denmark)

Schmidt, Jesper Hvass; Klokker, Mads

2014-01-01

BACKGROUND: Wind turbine noise exposure and suspected health-related effects thereof have attracted substantial attention. Various symptoms such as sleep-related problems, headache, tinnitus and vertigo have been described by subjects suspected of having been exposed to wind turbine noise...... existing statistically-significant evidence indicating any association between wind turbine noise exposure and tinnitus, hearing loss, vertigo or headache. LIMITATIONS: Selection bias and information bias of differing magnitudes were found to be present in all current studies investigating wind turbine...

Physiological and subjective responses to low relative humidity in young and elderly men.

Science.gov (United States)

Sunwoo, Yujin; Chou, Chinmei; Takeshita, Junko; Murakami, Motoko; Tochihara, Yutaka

2006-05-01

In order to compare the physiological and the subjective responses to low relative humidity of elderly and young men, we measured saccharin clearance time (SCT), frequency of blinking, hydration state of the skin, transepidermal water loss (TEWL), sebum level recovery and skin temperatures as physiological responses. We asked subjects to evaluate thermal, dryness and comfort sensations as subjective responses using a rating scale. Eight non-smoking healthy male students (21.7+/-0.8 yr) and eight non-smoking healthy elderly men (71.1+/-4.1 yr) were selected. The pre-room conditions were maintained at an air temperature (Ta) of 25 degrees C and a relative humidity (RH) of 50%. The test-room conditions were adjusted to provide 25 degrees C Ta and RH levels of 10%, 30% and 50%. RH had no effect on the activity of the sebaceous gland or change of mean skin temperature. SCT of the elderly group under 10% RH was significantly longer than that of the young group. In particular, considering the SCT change, the nasal mucous membrane seems to be affected more in the elderly than in the young in low RH. Under 30% RH, the eyes and skin become dry, and under 10% RH the nasal mucous membrane becomes dry as well as the eyes and skin. These findings suggested that to avoid dryness of the eyes and skin, it is necessary to maintain greater than 30% RH, and to avoid dryness of the nasal mucous membrane, it is necessary to maintain greater than 10% RH. On the thermal sensation of the legs, at the lower humidity level, the elderly group felt cooler than the young group. On the dry sensation of the eyes and throat, the young group felt drier than the elderly group at the lower humidity levels. From the above results, the elderly group had difficulty in feeling dryness in the nasal mucous membrane despite being easily affected by low humidity. On the other hand, the young group felt the change of humidity sensitively despite not being severely affected by low humidity. Ocular mucosa and

Effect of Temperature and Relative Humidity on the Growth of ...

African Journals Online (AJOL)

The effects of temperature and relative humidity on the growth of Helminthosporium fulvum were investigated. Various temperature regimes of 10oC, 15oC, 20oC, 25oC, 30oC, 35oC and 40¢ªC were used to determine the temperature effect on the growth of H. fulvum. Maximum growth of H. fulvum was obtained at 25¢ªC ...

Quantifying the Role of Atmospheric Forcing in Ice Edge Retreat and Advance Including Wind-Wave Coupling

Science.gov (United States)

2015-09-30

Low-Level Profiles, Pressure, Temperature, Humidity Rawinsonde (Kite, Tethered Balloon , Unmanned Aerial vehicle) Wave Characteristics, Wind wave and...Thermistor, Ship intake, Manual Bucket Tropospheric Profiles, 4/day – Pressure, Temperature, Humidity, Wind Vector Rawinsonde (Weather Balloon

Effects of relative humidity, temperature, and population density on production of cuticular hydrocarbons in housefly Musca domestica L.

NARCIS (Netherlands)

Noorman, N; Den Otter, CJ

The production of cuticular hydrocarbons by both males and females of Musca domestica L. under very wet conditions (90% relative humidity) compared to the production at 50 and 20% relative humidity is delayed up to at least 3 days after emergence from the pupae. Eight days after emergence, however,

Effect of Relative Humidity on Adsorption Breakthrough of CO2 on Activated Carbon Fibers

Directory of Open Access Journals (Sweden)

Yu-Chun Chiang

2017-11-01

Full Text Available Microporous activated carbon fibers (ACFs were developed for CO2 capture based on potassium hydroxide (KOH activation and tetraethylenepentamine (TEPA amination. The material properties of the modified ACFs were characterized using several techniques. The adsorption breakthrough curves of CO2 were measured and the effect of relative humidity in the carrier gas was determined. The KOH activation at high temperature generated additional pore networks and the intercalation of metallic K into the carbon matrix, leading to the production of mesopore and micropore volumes and providing access to the active sites in the micropores. However, this treatment also resulted in the loss of nitrogen functionalities. The TEPA amination has successfully introduced nitrogen functionalities onto the fiber surface, but its long-chain structure blocked parts of the micropores and, thus, made the available surface area and pore volume limited. Introduction of the power of time into the Wheeler equation was required to fit the data well. The relative humidity within the studied range had almost no effects on the breakthrough curves. It was expected that the concentration of CO2 was high enough so that the impact on CO2 adsorption capacity lessened due to increased relative humidity.

Influence of relative humidity and temperature on quantity of electric charge of static protective clothing used in petrochemical industry

Science.gov (United States)

Zhang, Yunpeng; Liu, Quanzhen; Liu, Baoquan; Li, Yipeng; Zhang, Tingting

2013-03-01

In this paper, the working principle of static protective clothing and its testing method of quantity of electric charge are introduced, and the influence of temperature and relative humidity on the quantity of electric charge (qe) of static protective clothing is studied by measuring qe of different clothing samples. The result shows that temperature and relative humidity can influence qe of static protective clothing to some extent and the influence of relative humidity is bigger than that of temperature. According to experimental results, the relationship of qe and relative humidity and temperature was analysed, and the safety boundary of quantity of electric charge is discussed. In order to reduce the occurrence of electrostatic accidents and ensure safe production and operation of petrochemical industry, some suggestions on choosing and using of static protective clothing are given for guaranteeing its static protective performance.

Energy-Efficient Management of Mechanical Ventilation and Relative Humidity in Hot-Humid Climates

Energy Technology Data Exchange (ETDEWEB)

Withers, Jr., Charles R. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States)

2016-12-01

In hot and humid climates, it is challenging to energy-efficiently maintain indoor RH at acceptable levels while simultaneously providing required ventilation, particularly in high performance low cooling load homes. The fundamental problem with solely relying on fixed capacity central cooling systems to manage moisture during low sensible load periods is that they are oversized for cooler periods of the year despite being 'properly sized' for a very hot design cooling day. The primary goals of this project were to determine the impact of supplementing a central space conditioning system with 1) a supplemental dehumidifier and 2) a ductless mini-split on seasonal energy use and summer peak power use as well as the impact on thermal distribution and humidity control inside a completely furnished lab home that was continuously ventilated in accordance with ASHRAE 62.2-2013.

Influence of relative humidity and temperature on quantity of electric charge of static protective clothing used in petrochemical industry

International Nuclear Information System (INIS)

Zhang, Yunpeng; Liu, Quanzhen; Liu, Baoquan; Li, Yipeng; Zhang, Tingting

2013-01-01

In this paper, the working principle of static protective clothing and its testing method of quantity of electric charge are introduced, and the influence of temperature and relative humidity on the quantity of electric charge (q e ) of static protective clothing is studied by measuring q e of different clothing samples. The result shows that temperature and relative humidity can influence q e of static protective clothing to some extent and the influence of relative humidity is bigger than that of temperature. According to experimental results, the relationship of q e and relative humidity and temperature was analysed, and the safety boundary of quantity of electric charge is discussed. In order to reduce the occurrence of electrostatic accidents and ensure safe production and operation of petrochemical industry, some suggestions on choosing and using of static protective clothing are given for guaranteeing its static protective performance.

The effect of relative humidity on output performance of inclined and ...

African Journals Online (AJOL)

The set-up of 70 Watts solar panel was inclined stationary at 150 for maximum solar reception while the set-up of 80 Watts solar panel had automatic solar tracker for effective capturing of solar radiation. For 70 Watts solar panel, the maximum power output of 59.99 Watt was obtained when the relative humidity was 30%.

Ultrahigh humidity sensitivity of graphene oxide.

Science.gov (United States)

Bi, Hengchang; Yin, Kuibo; Xie, Xiao; Ji, Jing; Wan, Shu; Sun, Litao; Terrones, Mauricio; Dresselhaus, Mildred S

2013-01-01

Humidity sensors have been extensively used in various fields, and numerous problems are encountered when using humidity sensors, including low sensitivity, long response and recovery times, and narrow humidity detection ranges. Using graphene oxide (G-O) films as humidity sensing materials, we fabricate here a microscale capacitive humidity sensor. Compared with conventional capacitive humidity sensors, the G-O based humidity sensor has a sensitivity of up to 37800% which is more than 10 times higher than that of the best one among conventional sensors at 15%-95% relative humidity. Moreover, our humidity sensor shows a fast response time (less than 1/4 of that of the conventional one) and recovery time (less than 1/2 of that of the conventional one). Therefore, G-O appears to be an ideal material for constructing humidity sensors with ultrahigh sensitivity for widespread applications.

Inter-Laboratory Comparison for Calibration of Relative Humidity Devices Among Accredited Laboratories in Malaysia

Science.gov (United States)

Hussain, F.; Khairuddin, S.; Othman, H.

2017-01-01

An inter-laboratory comparison in relative humidity measurements among accredited laboratories has been coordinated by the National Metrology Institute of Malaysia. It was carried out to determine the performance of the participating laboratories. The objective of the comparison was to acknowledge the participating laboratories competencies and to verify the level of accuracies declared in their scope of accreditation, in accordance with the MS ISO/IEC 17025 accreditation. The measurement parameter involved was relative humidity for the range of 30-90 %rh at a nominal temperature of 50°C. Eight accredited laboratories participated in the inter-laboratory comparison. Two units of artifacts have been circulated among the participants as the transfer standards.

Air humidity requirements for human comfort

DEFF Research Database (Denmark)

Toftum, Jørn; Fanger, Povl Ole

1999-01-01

level near 100% rh. For respiratory comfort are the requirements much more stringent and results in lower permissible indoor air humidities. Compared with the upper humidity limit specified in existing thermal comfort standards, e.g. ASHRAE Addendum 55a, the humidity limit based on skin humidity......Upper humidity limits for the comfort zone determined from two recently presented models for predicting discomfort due to skin humidity and insufficient respiratory cooling are proposed. The proposed limits are compared with the maximum permissible humidity level prescribed in existing standards...... for the thermal indoor environment. The skin humidity model predicts discomfort as a function of the relative humidity of the skin, which is determined by existing models for human heat and moisture transfer based on environmental parameters, clothing characteristics and activity level. The respiratory model...

Presence of stratospheric humidity in the ozone column depletion on the west coast of South America

International Nuclear Information System (INIS)

Da Silva, M. Luis; Gutierrez, O. Luis; Morales, S. Luis; Universidad de Chile, Santiago; Torres, C. Arnaldo

2006-01-01

The ozone column depletion over the western coast of South America has been previously explained, based on the existence of winds in the area of the depletion, which cause compression and thinning of the ozone layer. However, the presence of humidity and methane transported by these winds to the stratosphere where the ozone depletion is present gives evidence that these compounds also participate in the depletion of the ozone layer. These two compounds, humidity and methane, are analysed during the ozone depletion of January, 1998. It is observed that when humidity presents fluctuations, ozone has fluctuations too. A maximum of humidity corresponds to a minimum of ozone, but there is a shift in altitude between them. This shift is observed in the stratosphere and upper troposphere and corresponds to approximately 500 m. It is important to point out that during this event El Nino was present and the sources of methane are the Amazon forest and the Pacific Ocean. The data for this study was obtained from NASA and HALOE

Humidity Graphs for All Seasons.

Science.gov (United States)

Esmael, F.

1982-01-01

In a previous article in this journal (Vol. 17, p358, 1979), a wet-bulb depression table was recommended for two simple experiments to determine relative humidity. However, the use of a graph is suggested because it gives the relative humidity directly from the wet and dry bulb readings. (JN)

High relative humidity pre-harvest reduces post-harvest proliferation of Salmonella in tomatoes.

Science.gov (United States)

Devleesschauwer, Brecht; Marvasi, Massimiliano; Giurcanu, Mihai C; Hochmuth, George J; Speybroeck, Niko; Havelaar, Arie H; Teplitski, Max

2017-09-01

Outbreaks of human illness caused by enteric pathogens such as Salmonella are increasingly linked to the consumption of fruits and vegetables. Knowledge on the factors affecting Salmonella proliferation on fresh produce therefore becomes increasingly important to safeguard public health. Previous experiments showed a limited impact of pre-harvest production practices on Salmonella proliferation on tomatoes, but suggested a significant effect of harvest time. We explored the data from two previously published and one unpublished experiment using regression trees, which allowed overcoming the interpretational difficulties of classical statistical models with higher order interactions. We assessed the effect of harvest time by explicitly modeling the climatic conditions at harvest time and by performing confirmatory laboratory experiments. Across all datasets, regression trees confirmed the dominant effect of harvest time on Salmonella proliferation, with humidity-related factors emerging as the most important underlying climatic factors. High relative humidity the week prior to harvest was consistently associated with lower Salmonella proliferation. A controlled lab experiment confirmed that tomatoes containing their native epimicrobiota supported significantly lower Salmonella proliferation when incubated at higher humidity prior to inoculation. The complex interactions between environmental conditions and the native microbiota of the tomato crop remain to be fully understood. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaporative Cooler Use Influences Temporal Indoor Relative Humidity but Not Dust Mite Allergen Levels in Homes in a Semi-Arid Climate.

Science.gov (United States)

Johnston, James D; Tuttle, Steven C; Nelson, Morgan C; Bradshaw, Rebecca K; Hoybjerg, Taylor G; Johnson, Julene B; Kruman, Bryce A; Orton, Taylor S; Cook, Ryan B; Eggett, Dennis L; Weber, K Scott

2016-01-01

Concerns about energy consumption and climate change make residential evaporative coolers a popular alternative to central air conditioning in arid and semi-arid climates. However, evaporative coolers have been shown to significantly increase indoor relative humidity and dust mite allergen levels in some studies, while showing no association in other studies. Improved measurement of temporal fluctuations in indoor relative humidity may help identify factors that promote mite growth in homes in dry climates. Dust samples and continuous indoor relative humidity measurements were collected from homes with central air conditioning and homes with evaporative coolers in Utah. Samples were collected over two seasons, winter/spring (Jan-Apr) and summer (July-Sept), 2014. Dust samples were analyzed for Der p 1 and Der f 1 using a two-site monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) analysis. Housing characteristics including age of home, occupant density, and age of mattresses, furniture, and carpeting were also measured. Positive Der p 1 or Der f 1 samples were found in 25.0% of the homes and there was no difference in mean allergen levels by type of air conditioning. Indoor relative humidity was significantly higher in homes with evaporative coolers compared to those with central air conditioning during the summer. Homes with evaporative coolers also spent significantly more time during summer above 55.0% and 65.0% relative humidity compared to central air homes, but not above 75.0%. Findings from this study suggest that increased humidity from evaporative coolers may not be sufficient to exceed the critical equilibrium humidity or maintain humidity excursions for sufficient duration in relatively larger single-family homes in semi-arid climates to support mite growth and reproduction.

The role of absorbent building materials in moderating changes of relative humidity

DEFF Research Database (Denmark)

Padfield, Tim

The problem studied in this work is, how porous, absorbent materials surroundning or placed in a room influence the relative humidity of the room. This is of interest in designing precautions and machinery to monitor the indoor climate in museums and dwelling rooms. - A novel technique for the in...

Influence of the stratospheric humidity and methane on the ozone column depletion over the western side of South America

International Nuclear Information System (INIS)

Da Silva, L.; Morales, L.; Cordero, R.R.

2009-01-01

The ozone column depletion over the western side of South America has been previously explained as a consequence of winds in the area of the depletion, which lead to the compression and thinning of the ozone layer. However, humidity and methane (originated in the Amazon forest and the Pacific Ocean) transported by these winds toward the stratosphere may also have a role in the ozone depletion. Oxidation of methane generates additional humidity, which in turn reacts with ozone, destroying it. Humidity and methane levels were measured by NASA and HALOE during an ozone depletion event (January 1998) that occurred along with El Nino. By analyzing these measurements, we found that, at different altitudes, changes in the humidity seem to be associated with changes in the ozone such that an increment of humidity may lead to an ozone depletion. Moreover, we found that during the event, the sum 2CH4+H2O was roughly constant only at altitudes lower than 50 km; the ratio CH4/H2O exhibited an exponential decay with the altitude that may allow assessing the generation mechanism of stratospheric humidity from methane.

Humidity requirements in WSCF Laboratories

International Nuclear Information System (INIS)

Evans, R.A.

1994-01-01

The purpose of this paper is to develop and document a position on Relative Humidity (RH) requirements in the WSCF Laboratories. A current survey of equipment vendors for Organic, Inorganic and Radiochemical laboratories indicate that 25% - 80% relative humidity may meet the environmental requirements for safe operation and protection of all the laboratory equipment

Population growth and development of Liposcelis pearmani (Psocoptera: Liposcelididae) at constant temperatures and relative humidities.

Science.gov (United States)

Aminatou, B A; Gautam, S G; Opit, G P; Talley, J; Shakya, K

2011-08-01

Psocids of genus Liposcelis are now considered serious pests of stored products. We investigated the effects of eight temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, and 40.0°C) and four relative humidities (43, 55, 63, and 75%) on population growth and development of the psocid Liposcelis pearmani Lienhard. L. pearmani did not survive at 37.5 and 40.0°C, at all relative humidities tested; at 43% RH, at all temperatures tested; and at 55% RH, at 32.5 and 35°C. The greatest population growth was recorded at 32.5°C and 75% RH (32-fold growth). L. pearmani males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 17, 63, and 20%, respectively. Female L. pearmani have two to five instars, and the percentages of females with two, three, four, and five instars were 5, 39, 55, and 1%, respectively. We developed temperature-dependent development equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages. Based on 30-d population growth, L. pearmani cannot survive at temperatures >35.0°C; does not thrive at low relative humidities (55%), at temperatures above 25°C; and has a high optimum relative humidity for population growth (75%). Therefore, we expect it to have a more limited distribution compared with other Liposcelis species. These data provide a better understanding of how temperature and RH may influence L. pearmani population dynamics and can be used in population growth models to help develop effective management strategies for this psocid, and to predict its occurrence.

Evaporative Cooler Use Influences Temporal Indoor Relative Humidity but Not Dust Mite Allergen Levels in Homes in a Semi-Arid Climate.

Directory of Open Access Journals (Sweden)

James D Johnston

Full Text Available Concerns about energy consumption and climate change make residential evaporative coolers a popular alternative to central air conditioning in arid and semi-arid climates. However, evaporative coolers have been shown to significantly increase indoor relative humidity and dust mite allergen levels in some studies, while showing no association in other studies. Improved measurement of temporal fluctuations in indoor relative humidity may help identify factors that promote mite growth in homes in dry climates. Dust samples and continuous indoor relative humidity measurements were collected from homes with central air conditioning and homes with evaporative coolers in Utah. Samples were collected over two seasons, winter/spring (Jan-Apr and summer (July-Sept, 2014. Dust samples were analyzed for Der p 1 and Der f 1 using a two-site monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA analysis. Housing characteristics including age of home, occupant density, and age of mattresses, furniture, and carpeting were also measured. Positive Der p 1 or Der f 1 samples were found in 25.0% of the homes and there was no difference in mean allergen levels by type of air conditioning. Indoor relative humidity was significantly higher in homes with evaporative coolers compared to those with central air conditioning during the summer. Homes with evaporative coolers also spent significantly more time during summer above 55.0% and 65.0% relative humidity compared to central air homes, but not above 75.0%. Findings from this study suggest that increased humidity from evaporative coolers may not be sufficient to exceed the critical equilibrium humidity or maintain humidity excursions for sufficient duration in relatively larger single-family homes in semi-arid climates to support mite growth and reproduction.

Development of data logger for atmospheric pressure, temperature and relative humidity for gas-filled detector

International Nuclear Information System (INIS)

Sahu, S.; Sahu, P.K.; Bhuyan, M.R.; Biswas, S.; Mohanty, B.

2014-01-01

At IoP-NISER an initiative has been taken to build and test micro-pattern gas detector such as Gas Electron Multiplier (GEM) for several upcoming High-Energy Physics (HEP) experiment projects. Temperature (t), atmospheric pressure (p) and relative humidity (RH) monitor and recording is very important for gas filled detector development. A data logger to monitor and record the ambient parameters such as temperature, relative humidity and pressure has been developed. With this data logger continuous recording of t, p, RH and time stamp can be done with a programmable sampling interval. This data is necessary to correct the gain of a gas filled detector

Climate risk assessment in museums : degradation risks determined from temperature and relative humidity data

NARCIS (Netherlands)

Martens, M.H.J.

2012-01-01

The main subject of this thesis is the determination of climate risks to objects in museums on the basis of measured and/or simulated temperature and relative humidity data. The focus is on the quantification of climate related risks for the preservation quality of indoor climate in Dutch museums.

Humidity Sensing in Drosophila.

Science.gov (United States)

Enjin, Anders; Zaharieva, Emanuela E; Frank, Dominic D; Mansourian, Suzan; Suh, Greg S B; Gallio, Marco; Stensmyr, Marcus C

2016-05-23

Environmental humidity influences the fitness and geographic distribution of all animals [1]. Insects in particular use humidity cues to navigate the environment, and previous work suggests the existence of specific sensory mechanisms to detect favorable humidity ranges [2-5]. Yet, the molecular and cellular basis of humidity sensing (hygrosensation) remains poorly understood. Here we describe genes and neurons necessary for hygrosensation in the vinegar fly Drosophila melanogaster. We find that members of the Drosophila genus display species-specific humidity preferences related to conditions in their native habitats. Using a simple behavioral assay, we find that the ionotropic receptors IR40a, IR93a, and IR25a are all required for humidity preference in D. melanogaster. Yet, whereas IR40a is selectively required for hygrosensory responses, IR93a and IR25a mediate both humidity and temperature preference. Consistent with this, the expression of IR93a and IR25a includes thermosensory neurons of the arista. In contrast, IR40a is excluded from the arista but is expressed (and required) in specialized neurons innervating pore-less sensilla of the sacculus, a unique invagination of the third antennal segment. Indeed, calcium imaging showed that IR40a neurons directly respond to changes in humidity, and IR40a knockdown or IR93a mutation reduced their responses to stimuli. Taken together, our results suggest that the preference for a specific humidity range depends on specialized sacculus neurons, and that the processing of environmental humidity can happen largely in parallel to that of temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Humidity control device in a reactor container

International Nuclear Information System (INIS)

Aizawa, Motohiro; Igarashi, Hiroo; Osumi, Katsumi; Kimura, Takashi.

1986-01-01

Purpose: To provide a device capable of maintaining the inside of a container under high humidity circumstantial conditions causing less atmospheric corrosions, in order to prevent injuries due to atmospheric corrosions to smaller diameter stainless steel pipeways in the reactor container. Constitution: Stress corrosion cracks (SCC) to the smaller diameter stainless steel pipeways are caused dependent on the relative humidity and it is effective as the countermeasure against SCC to maintain the relative humidity at a low level less than 30 % or high level greater than 60 %. Based on the above findings, a humidity control device is disposed so as to maintain the relative humidity for the atmosphere within a reactor core on a higher humidity region. The device is adapted such that recycling gas in the dry-well coolant circuit is passed through an orifice to atomize the water introduced from feedwater pipe and introduce into a reactor core or such that the recycling gases in the dry-well cooling circuit are bubbled into water to remove chlorine gas in the reactor container gas thereby increasing the humidity in the reactor container. (Kamimura, M.)

Coupled effects of the temperature and the relative humidity on gecko adhesion

International Nuclear Information System (INIS)

Peng, Zhilong; Yang, Yazheng; Chen, Shaohua

2017-01-01

To explain the inconsistent results of experiments on temperature-dependent gecko adhesion, a theoretical peeling model is established wherein a nano-thin film is adopted to simulate a gecko spatula. The model considers not only the respective effects of temperature and environmental humidity on the peel-off force but also the coupled effect of both factors. Increasing temperature is found to lead to a decreasing peel-off force if the environmental humidity is uncontrolled. However, if the environmental humidity is constant, the peel-off force is insensitive to the temperature and remains almost constant. The synthetic theoretical analysis demonstrates that the seemingly contradictory results of temperature-dependent gecko adhesion experiments are actually consistent under their respective experimental conditions. This inconsistency is mainly due to the environmental humidity, which varies with the changing temperature if it is not artificially controlled. The results cannot only reasonably explain the different experimental results for the effect of temperature on gecko adhesion but can also facilitate the design of temperature-controlled or humidity-controlled adhesion sensors by tuning the environmental humidity or temperature. (paper)

Assistance to States on Policies Related to Wind Energy Issues

Energy Technology Data Exchange (ETDEWEB)

Brown, Matthew, H; Decesaro, Jennifer; DOE Project Officer - Keith Bennett

2005-07-15

This final report summarizes work carried out under agreement with the US Department of Energy, related to wind energy policy issues. This project has involved a combination of outreach and publications on wind energy, with a specific focus on educating state-level policymakers. Education of state policymakers is vitally important because state policy (in the form of incentives or regulation) is a crucial part of the success of wind energy. State policymakers wield a significant influence over all of these policies. They are also in need of high quality, non-biased educational resources which this project provided. This project provided outreach to legislatures, in the form of meetings designed specifically for state legislators and legislative staff, responses to information requests on wind energy, and publications. The publications addressed: renewable energy portfolio standards, wind energy transmission, wind energy siting, case studies of wind energy policy, avian issues, economic development, and other related issues. These publications were distributed to legislative energy committee members, and chairs, legislative staff, legislative libraries, and other related state officials. The effect of this effort has been to provide an extensive resource of information about wind information for state policymakers in a form that is useful to them. This non-partisan information has been used as state policymakers attempt to develop their own policy proposals related to wind energy in the states.

Physical activity profile of 2014 FIFA World Cup players, with regard to different ranges of air temperature and relative humidity

Science.gov (United States)

Chmura, Paweł; Konefał, Marek; Andrzejewski, Marcin; Kosowski, Jakub; Rokita, Andrzej; Chmura, Jan

2017-04-01

The present study attempts to assess changes in soccer players' physical activity profiles under the simultaneous influence of the different combinations of ambient temperature and relative humidity characterising matches of the 2014 FIFA World Cup hosted by Brazil. The study material consisted of observations of 340 players representing 32 national teams taking part in the tournament. The measured indices included total distances covered; distances covered with low, moderate, or high intensity; numbers of sprints performed, and peak running speeds achieved. The analysis was carried out using FIFA official match data from the Castrol Performance Index system. Ultimately, consideration was given to a combination of three air temperature ranges, i.e. below 22 °C, 22-28 °C, and above 28 °C; and two relative humidity ranges below 60 % and above 60 %. The greatest average distance recorded (10.54 ± 0.91 km) covered by players at an air temperature below 22 °C and a relative humidity below 60 %, while the shortest (9.83 ± 1.08 km) characterised the same air temperature range, but conditions of relative humidity above 60 % ( p ≤ 0.001). Two-way ANOVA revealed significant differences ( p ≤ 0.001) in numbers of sprints performed by players, depending on whether the air temperature range was below 22 °C (40.48 ± 11.17) or above 28 °C (30.72 ± 9.40), but only where the relative humidity was at the same time below 60 %. Results presented indicate that the conditions most comfortable for physical activity on the part of players occur at 22 °C, and with relative humidity under 60 %.

Health effects related to wind turbine noise exposure: a systematic review.

Science.gov (United States)

Schmidt, Jesper Hvass; Klokker, Mads

2014-01-01

Wind turbine noise exposure and suspected health-related effects thereof have attracted substantial attention. Various symptoms such as sleep-related problems, headache, tinnitus and vertigo have been described by subjects suspected of having been exposed to wind turbine noise. This review was conducted systematically with the purpose of identifying any reported associations between wind turbine noise exposure and suspected health-related effects. A search of the scientific literature concerning the health-related effects of wind turbine noise was conducted on PubMed, Web of Science, Google Scholar and various other Internet sources. All studies investigating suspected health-related outcomes associated with wind turbine noise exposure were included. Wind turbines emit noise, including low-frequency noise, which decreases incrementally with increases in distance from the wind turbines. Likewise, evidence of a dose-response relationship between wind turbine noise linked to noise annoyance, sleep disturbance and possibly even psychological distress was present in the literature. Currently, there is no further existing statistically-significant evidence indicating any association between wind turbine noise exposure and tinnitus, hearing loss, vertigo or headache. Selection bias and information bias of differing magnitudes were found to be present in all current studies investigating wind turbine noise exposure and adverse health effects. Only articles published in English, German or Scandinavian languages were reviewed. Exposure to wind turbines does seem to increase the risk of annoyance and self-reported sleep disturbance in a dose-response relationship. There appears, though, to be a tolerable level of around LAeq of 35 dB. Of the many other claimed health effects of wind turbine noise exposure reported in the literature, however, no conclusive evidence could be found. Future studies should focus on investigations aimed at objectively demonstrating whether or not

Efficiency of producing anion and relative humidity of the indigenous woody plants in Jeju islands

Science.gov (United States)

Son, S.-G.; Kim, K.-J.; Kim, H.-J.; Kim, C.-M.; Byun, K.-O.

2009-04-01

This study is to evaluate the ability of interior plants to produce anion and relative humidity that can purify polluted indoor air. Four indigenous woody plants in Jeju islands such as Sarcandra glaber (Thunb.) Nakai, Illicium anisatum L, Cleyera japonica Thunb. and Ilex rotunda Thunb. were used. Sansevieria trifasciata cv. Laurentii was also used as a comparative plant. The amount of anion and increment of relative humidity produced by five species of indoor plants was assessed by anion measurement (ITC-201A)in a sealed acryl chamber (118Ã-118Ã-119.5cm). The highest amount of anion was 515 ea/cm3produced by I. rotunda. The amounts of anion were 293 ea/cm3, 273 ea/cm3, and 211 ea/cm3 in S. glaber, I. anisatum and C. japonica, respecively while it was 220 ea/cm3 in S. trifasciata. The increment of relative humidity was highest in I. anisatum as 27.4% while it was lowest in S. trifasciata as 14.0%. This result suggested that all four indigenous plants tested were more effective to purify the indoor polluted air than S. trifasciata. Key words: interior plant, S. glaber, I. anisatum, C. japonica, I. rotunda, indoor polluted air

The influence of air temperature and relative humidity on dynamics of water potential in Betula pendula (Betulaceae trees

Directory of Open Access Journals (Sweden)

G. P. Тikhova

2017-02-01

Full Text Available Linear multiple models were developed to describe diurnal and seasonal dynamics of water potential (Ψ of the foliated shoots in the plants of Betula genus related to air temperature and relative humidity in the middle taiga (southern Karelia. The results of the study revealed unidirectional changes, but different effect strength of air temperature and relative humidity on Ψ of the foliated shoots of common silver birch (Betula pendula Roth and curly (Karelian birch (Betula pendula Roth var. carelica. It was shown that increasing air temperature 1°С results in similar decreasing of Ψ value equal to 0.037–0.038 MPa in both of the birches (p > 0.05. Since the diurnal air temperature range achieves 10–15 °С, the contribution of this factor may be up to 0.57 MPa. On the contrary, the contribution of relative air humidity to Ψ value differs significantly in distinct birch forms (p < 0.05. In this case the change range of Ψ value in silver birch and curly birch may be up to 0.46 (0.015 MPa/1 % RH and 0.52 МПа (0.017 MPa/1 % RH, respectively. The results indicate that curly birch responds to the increase of relative air humidity with higher magnification of Ψ in comparison with common silver birch.

Nucleation and Crystal Growth of Organic-Inorganic Lead Halide Perovskites under Different Relative Humidity.

Science.gov (United States)

Gao, Hao; Bao, Chunxiong; Li, Faming; Yu, Tao; Yang, Jie; Zhu, Weidong; Zhou, Xiaoxin; Fu, Gao; Zou, Zhigang

2015-05-06

Organic-inorganic lead halide perovskite compounds are very promising materials for high-efficiency perovskite solar cells. But how to fabricate high-quality perovksite films under controlled humidity conditions is still an important issue due to their sensitivity to moisture. In this study, we investigated the influence of ambient humidity on crystallization and surface morphology of one-step spin-coated perovskite films, as well as the performance of solar cells based on these perovskite films. On the basis of experimental analyses and thin film growth theory, we conclude that the influence of ambient humidity on nucleation at spin-coating stage is quite different from that on crystal growth at annealing stage. At the spin-coating stage, high nucleation density induced by high supersaturation prefers to appear under anhydrous circumstances, resulting in layer growth and high coverage of perovskite films. But at the annealing stage, the modest supersaturation benefits formation of perovskite films with good crystallinity. The films spin-coated under low relative humidity (RH) followed by annealing under high RH show an increase of crystallinity and improved performance of devices. Therefore, a mechanism of fast nucleation followed by modest crystal growth (high supersaturation at spin-coating stage and modest supersaturation at annealing stage) is suggested in the formation of high-quality perovskite films.

Effect of ambient temperature and relative humidity on interfacial temperature during early stages of drop evaporation.

Science.gov (United States)

Fukatani, Yuki; Orejon, Daniel; Kita, Yutaku; Takata, Yasuyuki; Kim, Jungho; Sefiane, Khellil

2016-04-01

Understanding drop evaporation mechanisms is important for many industrial, biological, and other applications. Drops of organic solvents undergoing evaporation have been found to display distinct thermal patterns, which in turn depend on the physical properties of the liquid, the substrate, and ambient conditions. These patterns have been reported previously to be bulk patterns from the solid-liquid to the liquid-gas drop interface. In the present work the effect of ambient temperature and humidity during the first stage of evaporation, i.e., pinned contact line, is studied paying special attention to the thermal information retrieved at the liquid-gas interface through IR thermography. This is coupled with drop profile monitoring to experimentally investigate the effect of ambient temperature and relative humidity on the drop interfacial thermal patterns and the evaporation rate. Results indicate that self-generated thermal patterns are enhanced by an increase in ambient temperature and/or a decrease in humidity. The more active thermal patterns observed at high ambient temperatures are explained in light of a greater temperature difference generated between the apex and the edge of the drop due to greater evaporative cooling. On the other hand, the presence of water humidity in the atmosphere is found to decrease the temperature difference along the drop interface due to the heat of adsorption, absorption and/or that of condensation of water onto the ethanol drops. The control, i.e., enhancement or suppression, of these thermal patterns at the drop interface by means of ambient temperature and relative humidity is quantified and reported.

Cultivar Differences in Plant Transpiration Rate at High Relative Air Humidity Are Not Related to Genotypic Variation in Stomatal Responsiveness

DEFF Research Database (Denmark)

Gebraegziabher, Habtamu Giday; Kjær, Katrine Heinsvig; Ottosen, Carl-Otto

2015-01-01

Plants grown at high relative air humidity (RH) often show disturbed water relations due to less responsive stomata. The attenuation of stomatal responsiveness as a result of high RH during leaf expansion depends on the cultivar. We hypothesized that tolerant cultivars to high RH experience a low...

The effects of building-related factors on classroom relative humidity among North Carolina schools participating in the 'Free to Breathe, Free to Teach' study.

Science.gov (United States)

Angelon-Gaetz, K A; Richardson, D B; Lipton, D M; Marshall, S W; Lamb, B; LoFrese, T

2015-12-01

Both high and low indoor relative humidity (RH) directly impact Indoor Air Quality (IAQ), an important school health concern. Prior school studies reported a high prevalence of mold, roaches, and water damage; however, few examined associations between modifiable classroom factors and RH, a quantitative indicator of dampness. We recorded RH longitudinally in 134 North Carolina classrooms (n = 9066 classroom-days) to quantify the relationships between modifiable classroom factors and average daily RH below, within, or above levels recommended to improve school IAQ (30-50% or 30-60% RH). The odds of having high RH (>60%) were 5.8 [95% Confidence Interval (CI): 2.9, 11.3] times higher in classrooms with annual compared to quarterly heating, ventilating, and air-conditioning (HVAC) system maintenance and 2.5 (95% CI: 1.5, 4.2) times higher in classrooms with HVAC economizers compared to those without economizers. Classrooms with direct-expansion split systems compared to chilled water systems had 2.7 (95% CI: 1.7, 4.4) times higher odds of low RH (60%) of those without setbacks. This research suggests actionable decision points for school design and maintenance to prevent high or low classroom RH. This study combines longitudinal measurements of classroom relative humidity with school inspection data from several schools to describe the problem of relative humidity control in schools. Our findings on how maintenance and mechanical factors affect classroom humidity provide suggestions on building operations policies and heating, ventilating, and air-conditioning (HVAC) design considerations that may improve classroom relative humidity control. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Evaporation Kinetics of Laboratory Generated Secondary Organic Aerosols at Elevated Relative Humidity

Energy Technology Data Exchange (ETDEWEB)

Wilson, Jacqueline M.; Imre, D.; Beranek, Josef; Shrivastava, ManishKumar B.; Zelenyuk, Alla

2015-01-06

Secondary organic aerosols (SOA) dominate atmospheric organic aerosols that affect climate, air quality, and health. Recent studies indicate that, contrary to previously held assumptions, at low relative humidity (RH) these particles are semi-solid and evaporate orders of magnitude slower than expected. Elevated relative humidity has the potential to affect significantly formation, properties, and atmospheric evolution of SOA particles. Here we present a study of the effect of RH on the room-temperature evaporation kinetics of SOA particles formed by ozonolysis of α-pinene and limonene. Experiments were carried out on SOA particles generated, evaporated, and aged at 0%, 50% and 90% RH. We find that in all cases evaporation begins with a relatively fast phase, during which 30% to 70% of the particle mass evaporates in 2 hours, followed by a much slower evaporation rate. Evaporation kinetics at 0% and 50% RH are nearly the same, while at 90% RH a slightly larger fraction evaporates. In all cases, aging the particles prior to inducing evaporation reduces the evaporative losses, with aging at elevated RH leading to more significant effect. In all cases, SOA evaporation is nearly size-independent, providing direct evidence that oligomers play a crucial role in determining the evaporation kinetics.

Role of relative humidity in processing and storage of seeds and assessment of variability in storage behaviour in Brassica spp. and Eruca sativa.

Science.gov (United States)

Suma, A; Sreenivasan, Kalyani; Singh, A K; Radhamani, J

2013-01-01

The role of relative humidity (RH) while processing and storing seeds of Brassica spp. and Eruca sativa was investigated by creating different levels of relative humidity, namely, 75%, 50%, 32%, and 11% using different saturated salt solutions and 1% RH using concentrated sulphuric acid. The variability in seed storage behaviour of different species of Brassica was also evaluated. The samples were stored at 40 ± 2°C in sealed containers and various physiological parameters were assessed at different intervals up to three months. The seed viability and seedling vigour parameters were considerably reduced in all accessions at high relative humidity irrespective of the species. Storage at intermediate relative humidities caused minimal decline in viability. All the accessions performed better at relative humidity level of 32% maintaining seed moisture content of 3%. On analyzing the variability in storage behaviour, B. rapa and B. juncea were better performers than B. napus and Eruca sativa.

Development of relative humidity models by using optimized neural network structures

Energy Technology Data Exchange (ETDEWEB)

Martinez-romero, A.; Ortega, J. F.; Juan, J. A.; Tarjuelo, J. M.; Moreno, M. A.

2010-07-01

Climate has always had a very important role in life on earth, as well as human activity and health. The influence of relative humidity (RH) in controlled environments (e.g. industrial processes in agro-food processing, cold storage of foods such as fruits, vegetables and meat, or controls in greenhouses) is very important. Relative humidity is a main factor in agricultural production and crop yield (due to the influence on crop water demand or the development and distribution of pests and diseases, for example). The main objective of this paper is to estimate RH [maximum (RHmax), average (RHave), and minimum (RHmin)] data in a specific area, being applied to the Region of Castilla-La Mancha (C-LM) in this case, from available data at thermo-pluviometric weather stations. In this paper Artificial neural networks (ANN) are used to generate RH considering maximum and minimum temperatures and extraterrestrial solar radiation data. Model validation and generation is based on data from the years 2000 to 2008 from 44 complete agroclimatic weather stations. Relative errors are estimated as 1) spatial errors of 11.30%, 6.80% and 10.27% and 2) temporal errors of 10.34%, 6.59% and 9.77% for RHmin, RHmax and RHave, respectively. The use of ANNs is interesting in generating climate parameters from available climate data. For determining optimal ANN structure in estimating RH values, model calibration and validation is necessary, considering spatial and temporal variability. (Author) 44 refs.

Measuring relative humidity in the radioactive environment of the IRRAD proton facility

CERN Document Server

Paerg, Marten

2017-01-01

The aim of the project was to obtain information on relative humidity conditions at different locations in the IRRAD proton facility. Due to high radiation levels inside the facility, different sensors had to be qualified and dedicated electronics had to be built to transfer the data of the sensors over long wires to a less radioactive area, where it could be collected.

Creep behavior of sweetgum OSB: effect of load level and relative humidity

Science.gov (United States)

J.H. Pu; R.C. Tang; Chung-Yun Hse

1994-01-01

Flexural creep behavior of laboratory-fabricated sweetgum oriented strandboard (OSB). under constnat (65% and 95%) and cyclic (65% 95% at a 96-hr. frequency) relative humidity (RH) conditions at 75 F (23.9 C) is presented. Two levels (4.5% and 6.5%) of resin content (RC) of phenol-formaldehyde were used in fabricating the test panels. Two load levels (20% and...

Influence of temperature on autogenous deformation and relative humidity change in hardening cement paste

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede; Hansen, Per Freiesleben

1999-01-01

This paper deals with autogenous deformation and autogenous relative humidity change (RH change) in hardening cement paste. Theoretical considerations and experimental data are presented, which elucidate the influence of temperature on these properties. This is an important subject in the control...

Synergistic interactions within disturbed habitats between temperature, relative humidity and UVB radiation on egg survival in a diadromous fish.

Directory of Open Access Journals (Sweden)

Michael J H Hickford

Full Text Available Anthropogenic impacts, including urbanization, deforestation, farming, and livestock grazing have altered riparian margins worldwide. One effect of changes to riparian vegetation is that the ground-level light, temperature, and humidity environment has also been altered. Galaxias maculatus, one of the most widely distributed fishes of the southern hemisphere, lays eggs almost exclusively beneath riparian vegetation in tidally influenced reaches of rivers. We hypothesized that the survival of these eggs is greatly affected by the micro-environment afforded by vegetation, particularly relating to temperature, humidity and UVB radiation. We experimentally reduced riparian vegetation height and altered shading characteristics, tracked egg survival, and used small ground-level temperature, humidity and UVB sensors to relate survival to ground-level effects around egg masses. The ground-level physical environment was markedly different from the surrounding ambient conditions. Tall dense riparian vegetation modified ambient conditions to produce a buffered temperature regime with constant high relative humidity, generally above 90%, and negligible UVB radiation at ground-level. Where vegetation height was reduced, frequent high temperatures, low humidity, and high UVB irradiances reduced egg survival by up to 95%. Temperature effects on egg survival were probably indirect, through reduced humidity, because developing eggs are known to survive in a wide range of temperatures. In this study, it was remarkable how such small variations in relatively small sites could have such a large effect on egg survival. It appears that modifications to riparian vegetation and the associated changes in the physical conditions of egg laying sites are major mechanisms affecting egg survival. The impacts associated with vegetational changes through human-induced disturbances are complex yet potentially devastating. These effects are particularly important because they

Humidity and Buildings. Technical Paper No. 188.

Science.gov (United States)

Hutcheon, N. B.

Modified and controlled relative humidity in buildings for certain occupancies is discussed. New criteria are used in determining the needs, desirability and problems associated with humidities in a building. Severe winter climate requires that special attention be given to the problems associated with increased indoor humidities during cold…

Relative humidity impact on aerosol parameters in a Paris suburban area

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H. Randriamiarisoa

2006-01-01

Full Text Available Measurements of relative humidity (RH and aerosol parameters (scattering cross section, size distributions and chemical composition, performed in ambient atmospheric conditions, have been used to study the influence of relative humidity on aerosol properties. The data were acquired in a suburban area south of Paris, between 18 and 24 July 2000, in the framework of the 'Etude et Simulation de la Qualité de l'air en Ile-de-France' (ESQUIF program. According to the origin of the air masses arriving over the Paris area, the aerosol hygroscopicity is more or less pronounced. The aerosol chemical composition data were used as input of a thermodynamic model to simulate the variation of the aerosol water mass content with ambient RH and to determine the main inorganic salt compounds. The coupling of observations and modelling reveals the presence of deliquescence processes with hysteresis phenomenon in the hygroscopic growth cycle. Based on the Hänel model, parameterisations of the scattering cross section, the modal radius of the accumulation mode of the size distribution and the aerosol water mass content, as a function of increasing RH, have been assessed. For the first time, a crosscheck of these parameterisations has been performed and shows that the hygroscopic behaviour of the accumulation mode can be coherently characterized by combined optical, size distribution and chemical measurements.

Odors and sensations of humidity and dryness in relation to sick building syndrome and home environment in Chongqing, China.

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Juan Wang

Full Text Available The prevalence of perceptions of odors and sensations of air humidity and sick building syndrome symptoms in domestic environments were studied using responses to a questionnaire on the home environment. Parents of 4530 1-8 year old children from randomly selected kindergartens in Chongqing, China participated. Stuffy odor, unpleasant odor, pungent odor, mold odor, tobacco smoke odor, humid air and dry air in the last three month (weekly or sometimes was reported by 31.4%, 26.5%, 16.1%, 10.6%, 33.0%, 32.1% and 37.2% of the parents, respectively. The prevalence of parents' SBS symptoms (weekly or sometimes were: 78.7% for general symptoms, 74.3% for mucosal symptoms and 47.5% for skin symptoms. Multi-nominal regression analyses for associations between odors/sensations of air humidity and SBS symptoms showed that the odds ratio for "weekly" SBS symptoms were consistently higher than for "sometimes" SBS symptoms. Living near a main road or highway, redecoration, and new furniture were risk factors for perceptions of odors and sensations of humid air and dry air. Dampness related problems (mold spots, damp stains, water damage and condensation were all risk factors for perceptions of odors and sensations of humid air and dry air, as was the presence of cockroaches, rats, and mosquitoes/flies, use of mosquito-repellent incense and incense. Protective factors included cleaning the child's bedroom every day and frequently exposing bedding to sunshine. In conclusion, adults' perceptions of odors and sensations of humid air and dry air are related to factors of the home environment and SBS symptoms are related to odor perceptions.

7 CFR 28.301 - Measurement: humidity; temperature.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Measurement: humidity; temperature. 28.301 Section 28... for Length of Staple § 28.301 Measurement: humidity; temperature. The length of staple of any cotton... its fibers under a relative humidity of the atmosphere of 65 percent and a temperature of 70° F. ...

The influence of temperature and humidity on abundance and richness of Calliphoridae (Diptera

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Rodrigo R. Azevedo

2013-06-01

Full Text Available The blowfly species are important components in necrophagous communities of the Neotropics. Besides being involved in the degradation of animal organic matter, they may serve as vectors for pathogens and parasites, and also cause primary and secondary myiasis. The occurrence pattern of these species is well defined, yet it is still not very clear which of these environmental factors determine the structure of the assemblies. This paper was developed to evaluate the influence of mean temperature and relative humidity variation in the abundance and richness of blowflies in the Brazilian southernmost state, Rio Grande do Sul, where temperature variation is well marked throughout the year. To evaluate this objective, WOT (Wind Oriented Trap were installed with beef liver as bait in three environments for 10 consecutive days in each month between July 2003 and June 2004. A total of 13,860 flies were collected distributed among 16 species with a higher frequency of Lucilia eximia (Wiedemann, 1819 and Chrysomya albiceps (Wiedemann, 1819. The mean temperature and relative humidity influence the richness of blowflies, with greater richness and abundance in late spring and early summer, whereas abundance was only influenced by temperature. Each species responded differently with respect to these variables, where L. eximia is not influenced by any of the two abiotic factors, despite the high abundance presented. This paper presents the results of the sensitivity for the presence or absence of species of Calliphoridae and on the variation of the abundance of these species under regime temperature changes and relative humidity with implications for public health and animal management.

The sensitivity to humidity of radon monitoring instruments

International Nuclear Information System (INIS)

Schmied, H.

1984-01-01

In a project funded by the Swedish Building Research Council (BFR) a continuous radon monitoring instrument (RGA-400 EDA Instr. Inc.) with electrostatic field collection has been calibrated. The original calibration factor gave no reliable radon readings and was therefore corrected for relative humidity by EDA. From four calibrations in the radon chamber at the Swedish Radiation Protection Board (SSI) it was clear that the instrument was sensitive to absolute humidity, which gave better agreement than relative humidity or temperature. Sensitivity to humidity for this principle of measure ment has been presented in various papers without presenting any combined influence with temperature, which can lead to the wrong conclusions, especially when the temperature levels differ. Some laboratories use humidity absorbants to overcome this humidity dependence. In this paper the calibration results for the FGA-400 radon readings only, are presented. (Author)

Application of graphene oxide based Microfiber-Knot resonator for relative humidity sensing

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S.R. Azzuhri

2018-06-01

Full Text Available A relative humidity (RH sensor is proposed and demonstrated using a micro-knot resonator (MKR enhanced with a layer graphene oxide (GO coating. The MKR is fabricated by means of tapering a standard fiber, with the GO coating added by the drop-cast method. The proposed sensor is tested for an RH range of between 0% and 80% at 20% intervals, and the configurations with and without the GO coating achieve sensitivities of 0.0104 nm/% and 0.0095 nm/%, respectively. The MKR configuration without the GO coating has a linear response correlation coefficient of 0.9098 and a resolution of 0.1%, while the configuration with the GO coating has a linear response correlation coefficient of 0.9548 and a resolution of 0.096% which is better. The proposed sensor has multiple applications, especially in the area of climate and atmospheric measurement and monitoring. Keywords: Microfiber, Resonator, Humidity sensor

Relative humidity sensor based on surface plasmon resonance of D-shaped fiber with polyvinyl alcohol embedding Au grating

Science.gov (United States)

Yan, Haitao; Han, Daofu; Li, Ming; Lin, Bo

2017-01-01

This paper presents the design, fabrication, and characterization of a D-shaped fiber coated with polyvinyl alcohol (PVA) embedding an Au grating-based relative humidity (RH) sensor. The Au grating is fabricated on a D-shaped fiber to match the wave-vector and excite the surface plasmon, and the PVA is embedded in the Au grating as a sensitive cladding film. The refractive index of PVA changes with the ambient humidity. Measurements in a controlled environment show that the RH sensor can achieve a sensitivity of 5.4 nm per relative humidity unit in the RH range from 0% to 70% RH. Moreover, the surface plasmon resonance can be realized and used for RH sensing at the C band of optical fiber communication instead of the visible light band due to the metallic grating microstructure on the D-shaped fiber.

Statistical Modelling of Temperature and Moisture Uptake of Biochars Exposed to Selected Relative Humidity of Air

Directory of Open Access Journals (Sweden)

Luciane Bastistella

2018-02-01

Full Text Available New experimental techniques, as well as modern variants on known methods, have recently been employed to investigate the fundamental reactions underlying the oxidation of biochar. The purpose of this paper was to experimentally and statistically study how the relative humidity of air, mass, and particle size of four biochars influenced the adsorption of water and the increase in temperature. A random factorial design was employed using the intuitive statistical software Xlstat. A simple linear regression model and an analysis of variance with a pairwise comparison were performed. The experimental study was carried out on the wood of Quercus pubescens, Cyclobalanopsis glauca, Trigonostemon huangmosun, and Bambusa vulgaris, and involved five relative humidity conditions (22, 43, 75, 84, and 90%, two mass samples (0.1 and 1 g, and two particle sizes (powder and piece. Two response variables including water adsorption and temperature increase were analyzed and discussed. The temperature did not increase linearly with the adsorption of water. Temperature was modeled by nine explanatory variables, while water adsorption was modeled by eight. Five variables, including factors and their interactions, were found to be common to the two models. Sample mass and relative humidity influenced the two qualitative variables, while particle size and biochar type only influenced the temperature.

Determination of equilibrium humidities using temperature and humidity controlled X-ray diffraction (RH-XRD)

International Nuclear Information System (INIS)

Linnow, Kirsten; Steiger, Michael

2007-01-01

Confined growth of crystals in porous building materials is generally considered to be a major cause of damage. We report on the use of X-ray diffraction under controlled conditions of temperature and relative humidity (RH-XRD) for the investigation of potentially deleterious phase transition reactions. An improved procedure based on rate measurements is used for the accurate and reproducible determination of equilibrium humidities of deliquescence and hydration reactions. The deliquescence humidities of NaCl (75.4 ± 0.5% RH) and Ca(NO 3 ) 2 .4H 2 O (50.8 ± 0.7% RH) at 25 deg. C determined with this improved RH-XRD technique are in excellent agreement with available literature data. Measurement of the hydration of anhydrous Ca(NO 3 ) 2 to form Ca(NO 3 ) 2 .2H 2 O revealed an equilibrium humidity of 10.2 ± 0.3%, which is also in reasonable agreement with available data. In conclusion, dynamic X-ray diffraction measurements are an appropriate method for the accurate and precise determination of equilibrium humidities with a number of interesting future applications

Effect of relative humidity and temperature control on in-cabin thermal comfort state: Thermodynamic and psychometric analyses

International Nuclear Information System (INIS)

Alahmer, A.; Omar, M.A.; Mayyas, A.; Dongri, Shan

2011-01-01

This manuscript discusses the effect of manipulating the Relative Humidity RH of in-cabin environment on the thermal comfort and human occupants' thermal sensation. The study uses thermodynamic and psychometric analyses, to incorporate the effect of changing RH along with the dry bulb temperature on human comfort. Specifically, the study computes the effect of changing the relative humidity on the amount of heat rejected from the passenger compartment and the effect of relative humidity on occupants comfort zone. A practical system implementation is also discussed in terms of an evaporative cooler design. The results show that changing the RH along with dry bulb temperature inside vehicular cabins can improve the air conditioning efficiency by reducing the heat removed while improving the Human comfort sensations as measured by the Predicted Mean Value PMV and the Predicted Percentage Dissatisfied PPD indices. - Highlights: → Investigates the effect of controlling the RH and dry bulb temperature on in-cabin thermal comfort and sensation. → Conducts the thermodynamic and psychometric analyses for changing the RH and temperature for in-cabin air conditioning. → Discusses a possible system implementation through an evaporative cooler design.

Effects of humidity and interlayer cations on the frictional strength of montmorillonite

Science.gov (United States)

Tetsuka, Hiroshi; Katayama, Ikuo; Sakuma, Hiroshi; Tamura, Kenji

2018-04-01

We developed a humidity control system in a biaxial friction testing machine to investigate the effect of relative humidity and interlayer cations on the frictional strength of montmorillonite. We carried out the frictional experiments on Na- and Ca-montmorillonite under controlled relative humidities (ca. 10, 30, 50, 70, and 90%) and at a constant temperature (95 °C). Our experimental results show that frictional strengths of both Na- and Ca-montmorillonite decrease systematically with increasing relative humidity. The friction coefficients of Na-montmorillonite decrease from 0.33 (at relative humidity of 10%) to 0.06 (at relative humidity of 93%) and those of Ca-montmorillonite decrease from 0.22 (at relative humidity of 11%) to 0.04 (at relative humidity of 91%). Our results also show that the frictional strength of Na-montmorillonite is higher than that of Ca-montmorillonite at a given relative humidity. These results reveal that the frictional strength of montmorillonite is sensitive to hydration state and interlayer cation species, suggesting that the strength of faults containing these clay minerals depends on the physical and chemical environment.[Figure not available: see fulltext.

Analysis of the system efficiency of an intermediate temperature proton exchange membrane fuel cell at elevated temperature and relative humidity conditions

International Nuclear Information System (INIS)

Jeon, Seung Won; Cha, Dowon; Kim, Hyung Soon; Kim, Yongchan

2016-01-01

Highlights: • System efficiency of PEMFC is evaluated at elevated temperature and humidity. • Operating parameters are optimized using response surface methodology. • The optimal operating parameters are T = 90.6 °C, RH = 100.0%, and ζ = 2.07. • The power output and system efficiency are 1.28 W and 15.8% at the optimum. • The system efficiency can be effectively improved by increasing relative humidity. - Abstract: Humidification of the membrane is very important in a proton exchange membrane fuel cell (PEMFC), to maintain high ionic conductivity. At an elevated temperature, a large amount of thermal energy is required for humidification because of the exponentially increased saturation vapor pressure. In this study, the system efficiency of a PEMFC was evaluated by considering the heat required for preheating/humidification and compression work. Three-dimensional steady-state simulations were conducted using Fluent 14 to simulate the electrochemical reactions. The operating conditions were optimized using response surface methodology by considering both the fuel cell output and system efficiency. In addition, the effects of operating parameters such as the temperature, relative humidity, and stoichiometric ratio were investigated. The system efficiency can be improved more effectively by increasing relative humidity rather than increasing operating temperature because the ionic conductivity of the membrane was strongly influenced by the relative humidity.

Trends in mean maximum temperature, mean minimum temperature and mean relative humidity for Lautoka, Fiji during 2003 – 2013

Directory of Open Access Journals (Sweden)

Syed S. Ghani

2017-12-01

Full Text Available The current work observes the trends in Lautoka’s temperature and relative humidity during the period 2003 – 2013, which were analyzed using the recently updated data obtained from Fiji Meteorological Services (FMS. Four elements, mean maximum temperature, mean minimum temperature along with diurnal temperature range (DTR and mean relative humidity are investigated. From 2003–2013, the annual mean temperature has been enhanced between 0.02 and 0.080C. The heating is more in minimum temperature than in maximum temperature, resulting in a decrease of diurnal temperature range. The statistically significant increase was mostly seen during the summer months of December and January. Mean Relative Humidity has also increased from 3% to 8%. The bases of abnormal climate conditions are also studied. These bases were defined with temperature or humidity anomalies in their appropriate time sequences. These established the observed findings and exhibited that climate has been becoming gradually damper and heater throughout Lautoka during this period. While we are only at an initial phase in the probable inclinations of temperature changes, ecological reactions to recent climate change are already evidently noticeable. So it is proposed that it would be easier to identify climate alteration in a small island nation like Fiji.

The influence of relative humidity on the dust measurement with the FH 62 I-N [1 m3.h-1

International Nuclear Information System (INIS)

Krasenbrink, A.

1990-01-01

The influence of relative humidity (rh) can be noticed evidently at continuous dust measurements if humidity increases rapidly up to more than 90%. This work investigated the possibilities to reduce the resulting error of taking up humidity by using two different types of glass fibre filters, the usual GF10 and its hydrophobic version GF10 HY. Compared with the results of the GF10 it could be shown that the GF10 HY takes up only 63% of humidity per time, yielding a concentration peak with an amount of 66% of the GF10 value. The total amount of absorbed humidity in mass units of the dust monitor differed between 30 μg and 50 μg for the GF10, and between 20 μg and 40 μg for the GF10 HY filter. (orig.) [de

Effects of ambient temperature, humidity, and other meteorological variables on hospital admissions for angina pectoris.

Science.gov (United States)

Abrignani, Maurizio G; Corrao, Salvatore; Biondo, Giovan B; Lombardo, Renzo M; Di Girolamo, Paola; Braschi, Annabella; Di Girolamo, Alberto; Novo, Salvatore

2012-06-01

Seasonal peaks in cardiovascular disease incidence have been widely reported, suggesting weather has a role. The aim of our study was to determine the influence of climatic variables on angina pectoris hospital admissions. We correlated the daily number of angina cases admitted to a western Sicilian hospital over a period of 12 years and local weather conditions (temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure) on a day-to-day basis. A total of 2459 consecutive patients were admitted over the period 1987-1998 (1562 men, 867 women; M/F - 1:8). A seasonal variation was found with a noticeable winter peak. The results of Multivariate Poisson analysis showed a significant association between the daily number of angina hospital admission, temperature, and humidity. Significant incidence relative ratios (95% confidence intervals/measure unit) were, in males, 0.988 (0.980-0.996) (p = 0.004) for minimal temperature, 0.990 (0.984-0.996) (p = 0.001) for maximal humidity, and 1.002 (1.000-1.004) (p = 0.045) for minimal humidity. The corresponding values in females were 0.973 (0.951-0.995) (p < 0.017) for maximal temperature and 1.024 (1.001-1.048) (p = 0.037) for minimal temperature. Environmental temperature and humidity may play an important role in the pathogenesis of angina, although it seems different according to the gender. These data may help to understand the mechanisms that trigger ischemic events and to better organize hospital assistance throughout the year.

Low Humidity Characteristics of Polymer-Based Capacitive Humidity Sensors

OpenAIRE

Majewski Jacek

2017-01-01

Polymer-based capacitive humidity sensors emerged around 40 years ago; nevertheless, they currently constitute large part of sensors’ market within a range of medium (climatic and industrial) humidity 20−80%RH due to their linearity, stability and cost-effectiveness. However, for low humidity values (0−20%RH) that type of sensor exhibits increasingly nonlinear characteristics with decreasing of humidity values. This paper presents the results of some experimental trials of CMOS polymer-based ...

Influence of air humidity on polymeric microresonators

International Nuclear Information System (INIS)

Schmid, S; Kühne, S; Hierold, C

2009-01-01

The influence of air humidity on polymeric microresonators is investigated by means of three different resonator types. SU-8 microbeams, SU-8 microstrings and a silicon micromirror with SU-8 hinges are exposed to relative humidities between 3% and 60%. The shifts of the resonant frequencies as a function of the relative humidity (RH) are explained based on mechanical models which are extended with water absorption models in polymer materials. The dominant effect causing the resonant frequency change is evaluated for each structure type. The eigenfrequency of the microstrings and the micromirror in the out-of-plane mode, which both mainly are defined by the pre-stress of the polymeric structures, are found to be highly sensitive to changes of air humidity. The humidity-induced (hygrometric) volume expansion reversibly reduces the pre-stress which results in relative frequency changes of up to 0.78%/%RH for the microstrings. A maximum coefficient of humidity-induced volume expansion for SU-8 of α hyg = 52.3 ppm/%RH is evaluated by fitting the data with the analytical model. It was found that microstrings that were stored at 150 °C over 150 h are more moisture sensitive compared to structures that were stored at room temperature. For the SU-8 microbeams and the micromirror in the tilt mode, the eigenfrequency is mainly defined by the modulus of the polymer material. The measured relative resonant frequency changes were below 1% for the given RH range. For low RH values, antiplasticization is observed (the modulus increases) followed by a plasticization for increasing RH values

Investigation of the influence of the microcapillary structure of natural skins on relative humidity in vacuum-sorption humidification

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Larina Ludmila

2017-01-01

Full Text Available The article presents the results of studies confirming the law of the gamma distribution of microcapillaries in the structure of materials having a stochastic structure, for example, natural skins. The relative humidity of the latter depends on the mass of moisture collected by the microcapillaries, with heat and mass transfer under vacuum conditions. Numerical values of relative humidity in this case may differ from those recommended by footwear manufacturing technologies and should be considered as an integral part of the phenomenon of high-intensity heat and mass transfer under vacuum conditions and be determined by the proposed models.

Population Growth and Development of the Psocid Liposcelis fusciceps (Psocoptera: Liposcelididae) at Constant Temperatures and Relative Humidities.

Science.gov (United States)

Gautam, S G; Opit, G P; Shakya, K

2016-02-01

We investigated the effects of seven temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, and 37.5°C) and four relative humidities (43, 55, 63, and 75%) on population growth and development of the psocid Liposcelis fusciceps Badonnel (Psocoptera: Liposcelididae). Results demonstrated that L. fusciceps did not survive at 43% RH, at all temperatures tested. At 55% RH, L. fusciceps did not survive at the highest three temperatures and no psocids survived at 37.5°C and 63% RH. The highest population growth was recorded at 30.0°C and 75% RH where populations increased 16-fold from an initial population of five females. L. fusciceps males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 28, 70, and 2%, respectively. Female L. fusciceps have two to five instars, and the percentages of females with two, three, four, and five instars were 2, 33, 63, and 2%, respectively. The total developmental time for males was shorter than females. We developed temperature-dependent development equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages. Based on 30-d population growth, L. fusciceps can survive and multiply at a relative humidity of 55% at 22.5-30.0°C, but does better at 27.5-32.5°C and a higher relative humidity of 75%. Relative humidities of ≤ 63% and temperatures of ≥ 32.5°C are detrimental to L. fusciceps. These data provide a better understanding of L. fusciceps population dynamics and can be used to develop effective management strategies for this psocid. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Indoor air purification by dielectric barrier discharge combined with ionic wind: physical and microbiological investigations

Science.gov (United States)

Timmermann, E.; Prehn, F.; Schmidt, M.; Höft, H.; Brandenburg, R.; Kettlitz, M.

2018-04-01

A non-thermal plasma source based on a surface dielectric barrier discharge (DBD) is developed for purification of recirculating air in operating theatres in hospitals. This is a challenging application due to high flow rates, short treatment times and the low threshold for ozone in the ventilated air. Therefore, the surface DBD was enhanced in order to generate an ionic wind, which can deflect and thus, filter out airborne microorganisms. Electrical and gas diagnostics as well as microbiological experiments were performed in a downscaled plasma source under variation of various electrical parameters, but application-oriented airflow velocity and humidity. The dependence of electrical power and ozone concentration as well as charged particles in the plasma treated air on frequency, voltage and relative humidity is presented and discussed. The presence of humidity causes a more conductive dielectric surface and thus a weaker plasma formation, especially at low frequency. The airborne test bacteria, Escherichia coli, showed significant effect to plasma treatment (up to 20% reduction) and to plasma with ionic wind (up to 90% removal); especially a configuration with 70% removal and an accompanying ozone concentration of only 360 ppb is promising for future application.

VAB Temperature and Humidity Study

Science.gov (United States)

Lane, John E.; Youngquist, Robert C.; Muktarian, Edward; Nurge, Mark A.

2014-01-01

In 2012, 17 data loggers were placed in the VAB to measure temperature and humidity at 10-minute intervals over a one-year period. In 2013, the data loggers were replaced with an upgraded model and slight adjustments to their locations were made to reduce direct solar heating effects. The data acquired by the data loggers was compared to temperature data provided by three wind towers located around the building. It was found that the VAB acts as a large thermal filter, delaying and reducing the thermal oscillations occurring outside of the building. This filtering is typically more pronounced at higher locations in the building, probably because these locations have less thermal connection with the outside. We surmise that the lower elevations respond more to outside temperature variations because of air flow through the doors. Temperatures inside the VAB rarely exceed outdoor temperatures, only doing so when measurements are made directly on a surface with connection to the outside (such as a door or wall) or when solar radiation falls directly on the sensor. A thermal model is presented to yield approximate filter response times for various locations in the building. Appendix A contains historical thermal and humidity data from 1994 to 2009.

A study of a wind catcher assisted adsorption cooling channel for natural cooling of a 2-storey building

International Nuclear Information System (INIS)

Haghighi, A.P.; Pakdel, S.H.; Jafari, A.

2016-01-01

This study proposes a new system composing of a wind catcher and a solar driven two-bed silica gel–water adsorption chiller in order to provide natural cooling of a two-story building. The wind catcher provides the required ventilation, and the air flowing though the wind catcher is cooled by the cooling plates fed by the adsorption chiller. The performance of the system is studied theoretically under different ambient conditions such as wind velocity, solar radiation, air temperature and relative humidity. In addition, the influence of geometric parameters such as size of the apertures, wind catcher's height and dimensions of the cooling plates and the number of them are studied. Furthermore, the system's capability to provide thermal comfort in the living space is investigated. It is found that at lower ACH (air change per hour) values, inlet air's temperature and absolute humidity reduce more. In addition, with the rise of the cooling plates' length, the cooling effect increases. The results indicated that with the increase of ACH values, thermal comfort condition is achieved for larger cooling demands. Furthermore, the system was found to be able to cool the air between 10 and 20 °C under different ambient conditions. - Highlights: • A new system consisting of a wind catcher and a solar adsorption chiller is proposed. • The values of ACH were compared under different geometrical parameters. • With the increase of ACH, thermal comfort can be achieved for larger cooling demands. • Thermal comfort is achieved for a maximum of 2200 W cooling demand in a 50 m 3 room. • Application of the system is found to be beneficial in hot and humid climates.

Ambient humidity and the skin: the impact of air humidity in healthy and diseased states.

Science.gov (United States)

Goad, N; Gawkrodger, D J

2016-08-01

Humidity, along with other climatic factors such as temperature and ultraviolet radiation, can have an important impact on the skin. Limited data suggest that external humidity influences the water content of the stratum corneum. An online literature search was conducted through Pub-Med using combinations of the following keywords: skin, skin disease, humidity, dermatoses, dermatitis, eczema, and mist. Publications included in this review were limited to (i) studies in humans or animals, (ii) publications showing relevance to the field of dermatology, (iii) studies published in English and (iv) publications discussing humidity as an independent influence on skin function. Studies examining environmental factors as composite influences on skin health are only included where the impact of humidity on the skin is also explored in isolation of other environmental factors. A formal systematic review was not feasible for this topic due to the heterogeneity of the available research. Epidemiological studies indicated an increase in eczema with low internal (indoors) humidity and an increase in eczema with external high humidity. Other studies suggest that symptoms of dry skin appear with low humidity internal air-conditioned environments. Murine studies determined that low humidity caused a number of changes in the skin, including the impairment of the desquamation process. Studies in humans demonstrated a reduction in transepidermal water loss (TEWL) (a measure of the integrity of the skin's barrier function) with low humidity, alterations in the water content in the stratum corneum, decreased skin elasticity and increased roughness. Intervention with a humidifying mist increased the water content of the stratum corneum. Conversely, there is some evidence that low humidity conditions can actually improve the barrier function of the skin. Ambient relative humidity has an impact on a range of parameters involved in skin health but the literature is inconclusive. Further

Hourly Wind Speed Interval Prediction in Arid Regions

Science.gov (United States)

Chaouch, M.; Ouarda, T.

2013-12-01

context, probabilistic forecasts might be more relevant than point forecasts for the planner to build scenarios In this paper, we are interested in estimating predictive intervals of the hourly wind speed measures in few cities in United Arab emirates (UAE). More precisely, given a wind speed time series, our target is to forecast the wind speed at any specific hour during the day and provide in addition an interval with the coverage probability 0flexible because it does not need a specification of the model to work with (such as normal distribution or a linear relation). Here, we use a covariable that is correlated to the wind speed. In practice, many possible choices of the covariate are available. In fact, in addition to its historical data, the wind speed is highly correlated to temperature, humidity and wind direction. In this paper a comparison, in terms of Mean Absolute Prediction Errors and Interquartile Range, between those choices will be provided to show which covariates are more suitable to forecast wind speed.

A Note on the Spatio Temporal Variations in the Temperature and Relative Humidity over Akure, Ondo State, Nigeria

Science.gov (United States)

Eludoyin, A. O.; Akinbode, O. M.; Archibong, E. O.

2007-07-01

This study was carried out in one of the Administrative State Capitals in the southwestern part of Nigeria. Its aim is to serve as a baseline data for highlighting the effect of spatial distribution of settlements, population, and socioeconomic activities on urban air temperature and relative humidity. The main objective of the study is to assess the impact of urban growth on the microclimate of the administrative city. Temperature and relative humidity data from 1992 to 2001 were obtained from the three existing meteorological stations in Akure, the Administrative Capital of Ondo State, Nigeria, namely the Federal Ministry of Aviation, Akure Airport station (FMA), Federal University of Technology, Akure (FUTA) and the Federal School of Agriculture (SOA). Air temperature and relative humidity measurements along primary roads and in the built up areas were obtained from seventeen stations, using sling psychrometer. The data were subsequently analysed for spatial and temporal variations. The results obtained indicated that while the maximum, average and minimum temperatures showed significant annual variations, the spatial variations among the existing meteorological stations were not significant. The city is characterized by increasing annual mean temperatures whose maximum was significantly higher than that of Ondo town — another important town within the state. The annual mean temperatures ranged between 26.2°C and 30.4°C. Minimum and maximum temperatures varied from 12.3°C to 26°C and 22.5°C to 39.6°C, respectively while the relative humidity ranged between 27.5% and 98.2%. Urban `heat island' intensity was exhibited around central business district of the Oba market. 2007 American Institute of Physics

Uncertainly Analysis of Two Types of Humidity Sensors by a Humidity Generator with a Divided-Flow System

Science.gov (United States)

Chen, Ling-Hsi

2018-01-01

Humidity measurement is an important technique for the agricultural, foods, pharmaceuticals, and chemical industries. For the sake of convenience, electrical relative humidity (RH) sensors have been widely used. These sensors need to be calibrated to ensure their accuracy and the uncertainty measurement of these sensors has become a major concern. In this study, a self-made divided-flow generator was established to calibrate two types of electrical humidity sensors. The standard reference humidity was calculated from dew-point temperature and air dry-bulb temperature measured by a chilled mirror monitor. This divided-flow generator could produce consistent result of RH measurement results. The uncertainty of the reference standard increased with the increase of RH values. The combined uncertainty with the adequate calibration equations were ranged from 0.82% to 1.45% RH for resistive humidity sensors and 0.63% to 1.4% for capacitive humidity sensors, respectively. This self-made, divided-flow generator, and calibration method are cheap, time-saving, and easy to be used. Thus, the proposed approach can easily be applied in research laboratories. PMID:29466313

Uncertainly Analysis of Two Types of Humidity Sensors by a Humidity Generator with a Divided-Flow System.

Science.gov (United States)

Chen, Ling-Hsi; Chen, Chiachung

2018-02-21

Humidity measurement is an important technique for the agricultural, foods, pharmaceuticals, and chemical industries. For the sake of convenience, electrical relative humidity (RH) sensors have been widely used. These sensors need to be calibrated to ensure their accuracy and the uncertainty measurement of these sensors has become a major concern. In this study, a self-made divided-flow generator was established to calibrate two types of electrical humidity sensors. The standard reference humidity was calculated from dew-point temperature and air dry-bulb temperature measured by a chilled mirror monitor. This divided-flow generator could produce consistent result of RH measurement results. The uncertainty of the reference standard increased with the increase of RH values. The combined uncertainty with the adequate calibration equations were ranged from 0.82% to 1.45% RH for resistive humidity sensors and 0.63% to 1.4% for capacitive humidity sensors, respectively. This self-made, divided-flow generator, and calibration method are cheap, time-saving, and easy to be used. Thus, the proposed approach can easily be applied in research laboratories.

Proposition of Regression Equations to Determine Outdoor Thermal Comfort in Tropical and Humid Environment

Directory of Open Access Journals (Sweden)

Sangkertadi Sangkertadi

2012-05-01

Full Text Available This study is about field experimentation in order to construct regression equations of perception of thermalcomfort for outdoor activities under hot and humid environment. Relationships between thermal-comfort perceptions, micro climate variables (temperatures and humidity and body parameters (activity, clothing, body measure have been observed and analyzed. 180 adults, men, and women participated as samples/respondents. This study is limited for situation where wind velocity is about 1 m/s, which touch the body of the respondents/samples. From questionnaires and field measurements, three regression equations have been developed, each for activity of normal walking, brisk walking, and sitting.

A Standard CMOS Humidity Sensor without Post-Processing

OpenAIRE

Nizhnik, Oleg; Higuchi, Kohei; Maenaka, Kazusuke

2011-01-01

A 2 ?W power dissipation, voltage-output, humidity sensor accurate to 5% relative humidity was developed using the LFoundry 0.15 ?m CMOS technology without post-processing. The sensor consists of a woven lateral array of electrodes implemented in CMOS top metal, a Intervia Photodielectric 8023?10 humidity-sensitive layer, and a CMOS capacitance to voltage converter.

Impact of wind-driven rain on historic brick wall buildings in a moderately cold and humid climate: Numerical analyses of mould growth risk, indoor climate and energy consumption

DEFF Research Database (Denmark)

Masaru, Abuku; Janssen, Hans; Roels, Staf

2009-01-01

This paper gives an onset to whole building hygrothermal modelling in which the interaction between interior and exterior climates via building enclosures is simulated under a moderately cold and humid climate. The focus is particularly on the impact of wind-driven rain (WDR) oil the hygrothermal...... response, mould growth at interior wall surfaces, indoor climate and energy consumption. First the WDR load oil the facades of a 4 m x 4 m x 10 m tower is determined. Then the hygrothermal behaviour of the brick walls is analysed oil a horizontal slice through the tower. The simulations demonstrate...

Biochars as Innovative Humidity Sensing Materials

Directory of Open Access Journals (Sweden)

Daniele Ziegler

2017-12-01

Full Text Available In this work, biochar-based humidity sensors were prepared by drop-coating technique. Polyvinylpyrrolidone (PVP was added as an organic binder to improve the adhesion of the sensing material onto ceramic substrates having platinum electrodes. Two biochars obtained from different precursors were used. The sensors were tested toward relative humidity (RH at room temperature and showed a response starting around 5 RH%, varying the impedance of 2 orders of magnitude after exposure to almost 100% relative humidity. In both cases, biochar materials are behaving as p-type semiconductors under low amounts of humidity. On the contrary, for higher RH values, the impedance decreased due to water molecules adsorption. When PVP is added to SWP700 biochar, n-p heterojunctions are formed between the two semiconductors, leading to a higher sensitivity at low RH values for the sensors SWP700-10% PVP and SWP700-20% PVP with respect to pure SWP700 sensor. Finally, response and recovery times were both reasonably fast (in the order of 1 min.

Adjustment of web-building initiation to high humidity: a constraint by humidity-dependent thread stickiness in the spider Cyrtarachne.

Science.gov (United States)

Baba, Yuki G; Kusahara, Miki; Maezono, Yasunori; Miyashita, Tadashi

2014-07-01

Cyrtarachne is an orb-weaving spider belonging to the subfamily Cyrtarachninae (Araneidae) which includes triangular-web-building Pasilobus and bolas spiders. The Cyrtarachninae is a group of spiders specialized in catching moths, which is thought to have evolved from ordinary orb-weaving araneids. Although the web-building time of nocturnal spiders is in general related to the time of sunset, anecdotal evidence has suggested variability of web-building time in Cyrtarachne and its closely related genera. This study has examined the effects of temperature, humidity, moonlight intensity, and prey (moths) availability on web-building time of Cyrtarachne bufo, Cyrtarachne akirai, and Cyrtarachne nagasakiensis. Generalized linear mixed model (GLMM) have revealed that humidity, and not prey availability, was the essential variable that explained the daily variability of web-building time. Experiments measuring thread stickiness under different humidities showed that, although the thread of Cyrtarachne was found to have strong stickiness under high humidity, low humidity caused a marked decrease of thread stickiness. By contrast, no obvious change in stickiness was seen in an ordinary orb-weaving spider, Larinia argiopiformis. These findings suggest that Cyrtarachne adjusts its web-building time to favorable conditions of high humidity maintaining strong stickiness, which enables the threads to work efficiently for capturing prey.

Air temperature and relative humidity in Dome Fuji Station buildings, East Antarctic ice sheet, in 2003

Directory of Open Access Journals (Sweden)

Takao Kameda

2008-06-01

Full Text Available In order to clarify the living condition in Dome Fuji Station in 2003, air temperature and relative humidity in the station were measured. Thermocouples with data logger and a ventilated psychrometer were used for the measurements. Average air temperature from February 11, 2003 to January 14, 2004 (missing period: July 19 to August 17 in the Dome Fuji Station buildings were as follows: Generator room 24.7℃, Dining room 23.5℃, Observation room 21.1℃, Dormitory room 18.2℃, Corridor 18.2℃, Food storage 8.2℃ and Old ice coring site -51.3℃. Average outside air temperature (1.5m height from the snow surface during the period was -54.4℃. A remarkable increase of outside air temperature (+30℃ at maximum due to a blocking high event was observed from October 31, 2003 to November 10, 2003 at Dome Fuji, during which increase of air temperature from 5 to 8°C in the station buildings was recorded. Snow on the station buildings was partly melted and some of the melted water penetrated into the station. This was the only time snow melted during the wintering over party's stay at the station. Average relative humidity in the station buildings obtained using a small humidifier was about 25%; the relative humidity without using the humidifier ranged from 9.0 to 22.9%.

External effects related to biogas and wind power

DEFF Research Database (Denmark)

Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

1998-01-01

Energy produced by wind power and biogas is today more expensive than energy produced by fossil fuels. However, by including external costs related to the technologies, the renewable technologies are expected to result in social benefits compared to the conventional power technologies. The paper...... will focus on estimates of externalities related to wind and biogas energy supplies using the ExternE methodology developed in a major study launched by the European Comission. External costs are the costs imporsed on society that are not included in the market price (e.g. effects of air pollution on health...

Density of loose-fill insulation material exposed to cyclic humidity conditions

DEFF Research Database (Denmark)

Rasmussen, Torben Valdbjørn

the granulated loose-fill material is exposed to a climate that is characterised as cyclic humidity conditions (a constant temperature and a relative humidity alternating between two predetermined constant relative humidity levels). A better understanding of the behaviour of granulated loose-fill material...

Temperature, humidity and time. Combined effects on radiochromic film dosimeters

DEFF Research Database (Denmark)

Abdel-Fattah, A.A.; Miller, A.

1996-01-01

The effects of both relative humidity and temperature during irradiation on the dose response of FWT-60-00 and Riso B3 radiochromic film dosimeters have been investigated in the relative humidity (RH) range 11-94% and temperature range 20-60 degrees C for irradiation by Co-60 photons and 10-Me......V electrons. The results show that humidity and temperature cannot be treated as independent variables, rather there appears to be interdependence between absorbed dose, temperature, and humidity. Dose rate does not seem to play a significant role. The dependence of temperature during irradiation is +0.......25 +/- 0.1% per degrees C for the FWT-60-00 dosimeters and +0.5 +/- 0.1% per degrees C For Riso B3 dosimeters at temperatures between 20 and 50 degrees C and at relative humidities between 20 and 53%. At extreme conditions both with respect to temperature and to humidity, the dosimeters show much stronger...

Changes of pressure and humidity affect olfactory function.

Science.gov (United States)

Kuehn, Michael; Welsch, Heiko; Zahnert, Thomas; Hummel, Thomas

2008-03-01

The present study aimed at investigating the question whether olfactory function changes in relation to barometric pressure and humidity. Using climate chambers, odor threshold and discrimination for butanol were tested in 75 healthy volunteers under hypobaric and hyperbaric, and different humidity conditions. Among other effects, olfactory sensitivity at threshold level, but not suprathreshold odor discrimination, was impaired in a hypobaric compared to a hyperbaric milieu, and thresholds were lower in humid, compared to relatively dry conditions. In conclusion, environmental conditions modulate the sense of smell, and may, consecutively, influence results from olfactory tests.

Humidity Effects on Fragmentation in Plasma-Based Ambient Ionization Sources.

Science.gov (United States)

Newsome, G Asher; Ackerman, Luke K; Johnson, Kevin J

2016-01-01

Post-plasma ambient desorption/ionization (ADI) sources are fundamentally dependent on surrounding water vapor to produce protonated analyte ions. There are two reports of humidity effects on ADI spectra. However, it is unclear whether humidity will affect all ADI sources and analytes, and by what mechanism humidity affects spectra. Flowing atmospheric pressure afterglow (FAPA) ionization and direct analysis in real time (DART) mass spectra of various surface-deposited and gas-phase analytes were acquired at ambient temperature and pressure across a range of observed humidity values. A controlled humidity enclosure around the ion source and mass spectrometer inlet was used to create programmed humidity and temperatures. The relative abundance and fragmentation of molecular adduct ions for several compounds consistently varied with changing ambient humidity and also were controlled with the humidity enclosure. For several compounds, increasing humidity decreased protonated molecule and other molecular adduct ion fragmentation in both FAPA and DART spectra. For others, humidity increased fragment ion ratios. The effects of humidity on molecular adduct ion fragmentation were caused by changes in the relative abundances of different reagent protonated water clusters and, thus, a change in the average difference in proton affinity between an analyte and the population of water clusters. Control of humidity in ambient post-plasma ion sources is needed to create spectral stability and reproducibility.

Trends in continental temperature and humidity directly linked to ocean warming.

Science.gov (United States)

Byrne, Michael P; O'Gorman, Paul A

2018-05-08

In recent decades, the land surface has warmed substantially more than the ocean surface, and relative humidity has fallen over land. Amplified warming and declining relative humidity over land are also dominant features of future climate projections, with implications for climate-change impacts. An emerging body of research has shown how constraints from atmospheric dynamics and moisture budgets are important for projected future land-ocean contrasts, but these ideas have not been used to investigate temperature and humidity records over recent decades. Here we show how both the temperature and humidity changes observed over land between 1979 and 2016 are linked to warming over neighboring oceans. A simple analytical theory, based on atmospheric dynamics and moisture transport, predicts equal changes in moist static energy over land and ocean and equal fractional changes in specific humidity over land and ocean. The theory is shown to be consistent with the observed trends in land temperature and humidity given the warming over ocean. Amplified land warming is needed for the increase in moist static energy over drier land to match that over ocean, and land relative humidity decreases because land specific humidity is linked via moisture transport to the weaker warming over ocean. However, there is considerable variability about the best-fit trend in land relative humidity that requires further investigation and which may be related to factors such as changes in atmospheric circulations and land-surface properties.

Comparison of land surface humidity between observations and CMIP5 models

Science.gov (United States)

Dunn, Robert J. H.; Willett, Kate M.; Ciavarella, Andrew; Stott, Peter A.

2017-08-01

We compare the latest observational land surface humidity dataset, HadISDH, with the latest generation of climate models extracted from the CMIP5 archive and the ERA-Interim reanalysis over the period 1973 to present. The globally averaged behaviour of HadISDH and ERA-Interim are very similar in both humidity measures and air temperature, on decadal and interannual timescales. The global average relative humidity shows a gradual increase from 1973 to 2000, followed by a steep decline in recent years. The observed specific humidity shows a steady increase in the global average during the early period but in the later period it remains approximately constant. None of the CMIP5 models or experiments capture the observed behaviour of the relative or specific humidity over the entire study period. When using an atmosphere-only model, driven by observed sea surface temperatures and radiative forcing changes, the behaviour of regional average temperature and specific humidity are better captured, but there is little improvement in the relative humidity. Comparing the observed climatologies with those from historical model runs shows that the models are generally cooler everywhere, are drier and less saturated in the tropics and extra-tropics, and have comparable moisture levels but are more saturated in the high latitudes. The spatial pattern of linear trends is relatively similar between the models and HadISDH for temperature and specific humidity, but there are large differences for relative humidity, with less moistening shown in the models over the tropics and very little at high latitudes. The observed drying in mid-latitudes is present at a much lower magnitude in the CMIP5 models. Relationships between temperature and humidity anomalies (T-q and T-rh) show good agreement for specific humidity between models and observations, and between the models themselves, but much poorer for relative humidity. The T-q correlation from the models is more steeply positive than

Reversible adhesion switching of porous fibrillar adhesive pads by humidity.

Science.gov (United States)

Xue, Longjian; Kovalev, Alexander; Dening, Kirstin; Eichler-Volf, Anna; Eickmeier, Henning; Haase, Markus; Enke, Dirk; Steinhart, Martin; Gorb, Stanislav N

2013-01-01

We report reversible adhesion switching on porous fibrillar polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) adhesive pads by humidity changes. Adhesion at a relative humidity of 90% was more than nine times higher than at a relative humidity of 2%. On nonporous fibrillar adhesive pads of the same material, adhesion increased only by a factor of ~3.3. The switching performance remained unchanged in at least 10 successive high/low humidity cycles. Main origin of enhanced adhesion at high humidity is the humidity-induced decrease in the elastic modulus of the polar component P2VP rather than capillary force. The presence of spongelike continuous internal pore systems with walls consisting of P2VP significantly leveraged this effect. Fibrillar adhesive pads on which adhesion is switchable by humidity changes may be used for preconcentration of airborne particulates, pollutants, and germs combined with triggered surface cleaning.

Laboratory Studies of Temperature and Relative Humidity Dependence of Aerosol Nucleation during the TANGENT 2017 IOP Study

Science.gov (United States)

Ouyang, Q.; Tiszenkel, L.; Stangl, C. M.; Krasnomowitz, J.; Johnston, M. V.; Lee, S.

2017-12-01

In this poster, we will present recent measurements of temperature and relative humidity dependence of aerosol nucleation of sulfuric acid under the conditions representative of the ground level to the free troposphere. Aerosol nucleation is critically dependent on temperature, but the current global aerosol models use nucleation algorithms that are independent of temperature and relative humidity due to the lack of experimental data. Thus, these models fail to simulate nucleation in a wide range of altitude and latitude conditions. We are currently conducting the Tandem Aerosol Nucleation and Growth Environment Tube (TANGENT) the intense observation period (IOP) experiments to investigate the aerosol nucleation and growth properties independently, during nucleation and growth. Nucleation takes place from sulfuric acid, water and some base compounds in a fast flow nucleation tube (FT-1). Nucleation precursors are detected with two chemical ionization mass spectrometers (CIMS) and newly nucleated particles are measured with a particle size magnifier (PSM) and a scanning mobility particle sizers (SMPS). Then these particles grow further in the second flow tube (FT-2) in the presence of oxidants of biogenic organic compounds. Chemical compositions of grown particles are further analyzed with a nano-aerosol mass spectrometer (NAMS). Our experimental results will provide a robust algorithm for aerosol nucleation and growth rates as a function of temperature and relative humidity.

In situ aerosol characterization at Cape Verde. Part 2: Parametrization of relative humidity- and wavelength-dependent aerosol optical properties

Energy Technology Data Exchange (ETDEWEB)

Schladitz, Alexander; Muller, Thomas; Nordmann, Stephan; Tesche, Matthias; Wiedensohler, Alfred (Leibniz Institute for Tropospheric Research (IfT), Leipzig (Germany)), e-mail: alexander.schladitz@tropos.de; Gross, Silke; Freudenthaler, Volker; Gasteiger, Josef (Meteorological Institute, Ludwig-Maximilians-Universitaet, Munich (Germany))

2011-09-15

An observation-based numerical study of humidity-dependent aerosol optical properties of mixed marine and Saharan mineral dust aerosol is presented. An aerosol model was developed based on measured optical and microphysical properties to describe the marine and Saharan dust aerosol at Cape Verde. A wavelength-dependent optical equivalent imaginary part of the refractive index and a scattering non-sphericity factor for Saharan dust were derived. Simulations of humidity effects on optical properties by the aerosol model were validated with relative measurements of the extinction coefficient at ambient conditions. Parametrizations were derived to describe the humidity dependence of the extinction, scattering, and absorption coefficients as well as the asymmetry parameter and single scattering albedo. For wavelengths (300-950 nm) and dry dust volume fractions (0-1), aerosol optical properties as a function of relative humidity (RH = 0-90%) can be calculated from tabulated parameters. For instance, at a wavelength of 550 nm, a volume fraction of 0.5 of dust on the total particle volume (dry conditions) and a RH of 90%, the enhancements for the scattering, extinction and absorption coefficients are 2.55, 2.46 and 1.04, respectively, while the enhancements for the asymmetry parameter and single scattering albedo are 1.11 and 1.04

Influence of relative humidity of air on the level of aqueous tritium in corn, wheat and sunflower

International Nuclear Information System (INIS)

Indeka, L.

1981-01-01

The short-term changes in level of aqueous tritium in the leaves in relation to the air humidity were studied. The experiments were carried out on corn in which the transpiration is relatively small, on sunflower with very high transpiration and on wheat with intermediate transpiration. (M.F.W.)

Attribution of observed surface humidity changes to human influence.

Science.gov (United States)

Willett, Katharine M; Gillett, Nathan P; Jones, Philip D; Thorne, Peter W

2007-10-11

Water vapour is the most important contributor to the natural greenhouse effect, and the amount of water vapour in the atmosphere is expected to increase under conditions of greenhouse-gas-induced warming, leading to a significant feedback on anthropogenic climate change. Theoretical and modelling studies predict that relative humidity will remain approximately constant at the global scale as the climate warms, leading to an increase in specific humidity. Although significant increases in surface specific humidity have been identified in several regions, and on the global scale in non-homogenized data, it has not been shown whether these changes are due to natural or human influences on climate. Here we use a new quality-controlled and homogenized gridded observational data set of surface humidity, with output from a coupled climate model, to identify and explore the causes of changes in surface specific humidity over the late twentieth century. We identify a significant global-scale increase in surface specific humidity that is attributable mainly to human influence. Specific humidity is found to have increased in response to rising temperatures, with relative humidity remaining approximately constant. These changes may have important implications, because atmospheric humidity is a key variable in determining the geographical distribution and maximum intensity of precipitation, the potential maximum intensity of tropical cyclones, and human heat stress, and has important effects on the biosphere and surface hydrology.

Humidity: A review and primer on atmospheric moisture and human health.

Science.gov (United States)

Davis, Robert E; McGregor, Glenn R; Enfield, Kyle B

2016-01-01

Research examining associations between weather and human health frequently includes the effects of atmospheric humidity. A large number of humidity variables have been developed for numerous purposes, but little guidance is available to health researchers regarding appropriate variable selection. We examine a suite of commonly used humidity variables and summarize both the medical and biometeorological literature on associations between humidity and human health. As an example of the importance of humidity variable selection, we correlate numerous hourly humidity variables to daily respiratory syncytial virus isolates in Singapore from 1992 to 1994. Most water-vapor mass based variables (specific humidity, absolute humidity, mixing ratio, dewpoint temperature, vapor pressure) exhibit comparable correlations. Variables that include a thermal component (relative humidity, dewpoint depression, saturation vapor pressure) exhibit strong diurnality and seasonality. Humidity variable selection must be dictated by the underlying research question. Despite being the most commonly used humidity variable, relative humidity should be used sparingly and avoided in cases when the proximity to saturation is not medically relevant. Care must be taken in averaging certain humidity variables daily or seasonally to avoid statistical biasing associated with variables that are inherently diurnal through their relationship to temperature. Copyright © 2015 Elsevier Inc. All rights reserved.

Mitigation of aflatoxin contamination in maize kernels is related to the metabolic alternation of reactive oxygen and nitrogen species by relative humidity

Science.gov (United States)

Environmental factors have been shown to be linked to exacerbated infection of maize kernels by Aspergillus flavus and subsequent aflatoxin contamination. Kernel resistance to aflatoxin contamination is associated with kernel water content and relative humidity during in vitro assays examining aflat...

Deformation of high performance concrete plate under humid tropical weather

Science.gov (United States)

Niken, C.; Elly, T.; Supartono, FX; Laksmi, I.

2018-03-01

This paper presents the relationship between surrounding relative humidity and temperature on deformation behavior of one sample concrete plate with compressive strength of 60MPa. This research was done in Indonesia that is in humid tropical weather. A specimens measuring 3000 mm × 1600 mm × 150 mm were used. The behavior was obtained by using four embedded vibrating wire strain gauges (VWESG). As a result there is a very strong relationship between humidity and deformation at the age range of 7 until 21 days. The largest deformation occurs in the corner and the fluctuation of deformation in side position is larger than in the corner and in the middle. The peaks of surrounding relative humidity were fully followed by the deepest valley of deformation on time in the corner, while in another position the range delay time was 8 - 11 hours. There is a strong relationship between surrounding temperature and deformation at the range of 7 until 14 days. The influenced of surrounding relative humidity to concrete behavior is faster and longer than surrounding temperature. The influence of surrounding temperature in humid tropical weather was shorter than in non-humid tropical weather.

Humidity Sensors Printed on Recycled Paper and Cardboard

Directory of Open Access Journals (Sweden)

Matija Mraović

2014-07-01

Full Text Available Research, design, fabrication and results of various screen printed capacitive humidity sensors is presented in this paper. Two types of capacitive humidity sensors have been designed and fabricated via screen printing on recycled paper and cardboard, obtained from the regional paper and cardboard industry. As printing ink, commercially available silver nanoparticle-based conductive ink was used. A considerable amount of work has been devoted to the humidity measurement methods using paper as a dielectric material. Performances of different structures have been tested in a humidity chamber. Relative humidity in the chamber was varied in the range of 35%–80% relative humidity (RH at a constant temperature of 23 °C. Parameters of interest were capacitance and conductance of each sensor material, as well as long term behaviour. Process reversibility has also been considered. The results obtained show a mainly logarithmic response of the paper sensors, with the only exception being cardboard-based sensors. Recycled paper-based sensors exhibit a change in value of three orders of magnitude, whereas cardboard-based sensors have a change in value of few 10s over the entire scope of relative humidity range (RH 35%–90%. Two different types of capacitor sensors have been investigated: lateral (comb type sensors and modified, perforated flat plate type sensors. The objective of the present work was to identify the most important factors affecting the material performances with humidity, and to contribute to the development of a sensor system supported with a Radio Frequency Identification (RFID chip directly on the material, for use in smart packaging applications. Therefore, the authors built a passive and a battery-supported wireless module based on SL900A smart sensory tag’s IC to achieve UHF-RFID functionality with data logging capability.

Cluster size influence on the survivability of Rhipicephalus Boophilus microplus larvae under low relative humidity stress

Science.gov (United States)

Low relative humidity (RH) levels (=63%) have been previously shown to be a determining factor in the survival of southern cattle fever tick, Rhipicephalus microplus, larvae, regardless of temperature. Supporting this observation, large larval clusters can retain more water than isolated larvae. Th...

Life cycle assessment of a wind farm and related externalities

DEFF Research Database (Denmark)

Schleisner, Liselotte

2000-01-01

This paper concentrates on the assessment of energy and emissions related to the production and manufacture of materials for an offshore wind farm as well as a wind farm on land based on a life cycle analysis (LCA) model. In Denmark a model has been developed for life cycle assessments of different...... materials. The model is able to assess the energy use related to the production, transportation and manufacture of 1 kg of material. The energy use is divided into fuels used in order to estimate the emissions through the life cycle. In the paper the model and the attached assumptions are described......, and the model is demonstrated for two wind farms. The externalities for the wind farms are reported, showing the importance of life cycle assessment for renewable energy technologies. (C) 2000 Elsevier Science Ltd. All rights reserved....

Long-term Effects of Relative Humidity on Properties of Microwave Hardened Moulding Sand with Sodium Silicate

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Stachowicz M.

2017-09-01

Full Text Available Moulding sands containing sodium silicate (water-glass belong to the group of porous mixture with low resistance to increased humidity. Thanks to hydrophilic properties of hardened or even overheated binder, possible is application of effective methods of hydrous reclamation consisting in its secondary hydration. For the same reason (hydrophilia of the binder, moulds and foundry cores made of high-silica moulding sands with sodium silicate are susceptible to the action of components of atmospheric air, including the contained steam. This paper presents results of a research on the effect of (relative humidity on mechanical and technological properties of microwave-hardened moulding mixtures. Specimens of the moulding sand containing 1.5 wt% of sodium water-glass with module 2.5 were subjected, in a laboratory climatic chamber, to long-term action of steam contained in the chamber atmosphere. Concentration of water in atmospheric air was stabilized for 28 days (672 h according to the relative humidity parameter that was ca. 40%, 60% and 80% at constant temperature 20 °C. In three cycles of the examinations, the specimens were taken out from the chamber every 7 days (168 h and their mechanical and technological parameters were determined. It was found on the grounds of laboratory measurements that moulds and cores hardened with microwaves are susceptible to action of atmospheric air and presence of water (as steam intensifies action of the air components on glassy film of sodium silicate. Microwave-hardened moulding sands containing sodium silicate may be stored on a long-term basis in strictly determined atmospheric conditions only, at reduced humidity. In spite of a negative effect of steam contained in the air, the examined moulding mixtures maintain a part of their mechanical and technological properties, so the moulds and foundry cores stored in specified, controlled conditions could be still used in manufacture.

Static flexural properties of hedgehog spines conditioned in coupled temperature and relative humidity environments.

Science.gov (United States)

Kennedy, Emily B; Hsiung, Bor-Kai; Swift, Nathan B; Tan, Kwek-Tze

2017-11-01

Hedgehogs are agile climbers, scaling trees and plants to heights exceeding 10m while foraging insects. Hedgehog spines (a.k.a. quills) provide fall protection by absorbing shock and could offer insights for the design of lightweight, material-efficient, impact-resistant structures. There has been some study of flexural properties of hedgehog spines, but an understanding of how this keratinous biological material is affected by various temperature and relative humidity treatments, or how spine color (multicolored vs. white) affects mechanics, is lacking. To bridge this gap in the literature, we use three-point bending to analyze the effect of temperature, humidity, spine color, and their interactions on flexural strength and modulus of hedgehog spines. We also compare specific strength and stiffness of hedgehog spines to conventional engineered materials. We find hedgehog spine flexural properties can be finely tuned by modifying environmental conditioning parameters. White spines tend to be stronger and stiffer than multicolored spines. Finally, for most temperature and humidity conditioning parameters, hedgehog spines are ounce for ounce stronger than 201 stainless steel rods of the same diameter but as pliable as styrene rods with a slightly larger diameter. This unique combination of strength and elasticity makes hedgehog spines exemplary shock absorbers, and a suitable reference model for biomimicry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Calibration of Relative Humidity Devices in Low-pressure, Low-temperature CO2 Environment

Science.gov (United States)

Genzer, Maria; Polkko, Jouni; Nikkanen, Timo; Hieta, Maria; Harri, Ari-Matti

2017-04-01

Calibration of relative humidity devices requires in minimum two humidity points - dry (0%RH) and (near)saturation (95-100%RH) - over the expected operational temperature and pressure range of the device. In terrestrial applications these are relatively easy to achieve using for example N2 gas as dry medium, and water vapor saturation chambers for producing saturation and intermediate humidity points. But for example in applications intended for meteorological measurements on Mars there is a need to achieve at least dry and saturation points in low-temperature, low-pressure CO2 environment. We have developed a custom-made, small, relatively low-cost calibration chamber able to produce both dry points and saturation points in Martian range pressure CO2, in temperatures down to -70°C. The system utilizes a commercially available temperature chamber for temperature control, vacuum vessels and pumps. The main pressure vessel with the devices under test inside is placed inside the temperature chamber, and the pressure inside is controlled by pumps and manual valves and monitored with a commercial pressure reference with calibration traceable to national standards. Air, CO2, or if needed another gas like N2, is used for filling the vessel until the desired pressure is achieved. Another pressure vessel with a dedicated pressure pump is used as the saturation chamber. This vessel is placed in the room outside the temperature chamber, partly filled with water and used for achieving saturated water vapor in room-temperature low-pressure environment. The saturation chamber is connected to the main pressure vessel via valves. In this system dry point, low-pressure CO2 environment is achieved by filling the main pressure vessel with dry CO2 gas until the desired pressure is achieved. A constant flow of gas is maintained with the pump and valves and monitored with the pressure reference. The saturation point is then achieved by adding some water vapor from the saturation

Methods of humidity determination Part II: Determination of material humidity

OpenAIRE

Rübner, Katrin; Balköse, Devrim; Robens, E.

2008-01-01

Part II covers the most common methods of measuring the humidity of solid material. State of water near solid surfaces, gravimetric measurement of material humidity, measurement of water sorption isotherms, chemical methods for determination of water content, measurement of material humidity via the gas phase, standardisation, cosmonautical observations are reviewed.

A distribution law for relative humidity in the upper troposphere and lower stratosphere derived from three years of MOZAIC measurements

Directory of Open Access Journals (Sweden)

K. Gierens

1999-09-01

Full Text Available Data from three years of MOZAIC measurements made it possible to determine a distribution law for the relative humidity in the upper troposphere and lower stratosphere. Data amounting to 13.5% of the total were obtained in regions with ice supersaturation. Troposphere and stratosphere are distinguished by an ozone concentration of 130 ppbv as threshold. The probability of measuring a certain amount of ice supersaturation in the troposphere decreases exponentially with the degree of ice supersaturation. The probability of measuring a certain relative humidity in the stratosphere (both with respect to water and ice decreases exponentially with the relative humidity. A stochastic model that naturally leads to the exponential distribution is provided. Mean supersaturation in the troposphere is about 15%, whereas ice nucleation requires 30% supersaturation on the average. This explains the frequency of regions in which aircraft induce persistent contrails but which are otherwise free of clouds. Ice supersaturated regions are 3-4 K colder and contain more than 50% more vapour than other regions in the upper troposphere. The stratospheric air masses sampled are dry, as expected, having mean relative humidity over water of 12% and over ice of 23%, respectively. However, 2% of the stratospheric data indicate ice supersaturation. As the MOZAIC measurements have been obtained on commercial flights mainly between Europe and North America, the data do not provide a complete global picture, but the exponential character of the distribution laws found is probably valid globally. Since water vapour is the most important greenhouse gas and since it might enhance the anthropogenic greenhouse effects via positive feedback mechanisms, it is important to represent its distribution correctly in climate models. The discovery of the distribution law of the relative humidity makes possible simple tests to show whether the hydrological cycle in climate models is

Humidity level In psychrometric processes

International Nuclear Information System (INIS)

Mojsovski, Filip

2008-01-01

When a thermal engineer needs to control, rather than merely moderate humidity, he must focus on the moisture level as a separate variable - not simply an addition of temperature control. Controlling humidity generally demands a correct psychrometric approach dedicated to that purpose [1].Analysis of the humidity level in psychrometric thermal processes leads to relevant data for theory and practice [2]. This paper presents: (1) the summer climatic curve for the Skopje region, (2) selected results of investigation on farm dryers made outside laboratories. The first purpose of such activity was to examine relations between weather conditions and drying conditions. The estimation of weather condition for the warmest season of the year was realized by a summer climatic curve. In the science of drying, basic drying conditions are temperature, relative humidity and velocity of air, thickness of dried product and dryer construction. The second purpose was to realize correct prediction of drying rates for various psychrometrics drying processes and local products. Test runs with the dryer were carried out over a period of 24 h, using fruits and vegetables as experimental material. Air flow rate through the dryer of 150 m3/h, overall drying rate of 0.04 kg/h and air temperature of 65 oC were reached. Three types of solar dryers, were exploited in the research.

Humidity Response of Polyaniline Based Sensor

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Mamta PANDEY

2010-02-01

Full Text Available Abstract: This paper presents hitherto unreported humidity sensing capacity of emeraldine salt form of polyaniline. Humidity plays a major role in different processes in industries ranging from food to electronic goods besides human comfort and therefore its monitoring is an essential requirement during various processes. Polyaniline has a wide use for making sensors as it can be easily synthesized and has long stability. Polyaniline is synthesized here by chemical route and is found to sense humidity as it shows variation in electrical resistance with variation in relative humidity. Results are presented here for a range of 15 to 90 RH%. The resistance falls from 5.8 to 0.72 Giga ohms as RH varies from 15 to 65 % and then falls to 13.9 Mega ohms as RH approaches 90 %. The response and recovery times are also measured.

Humidity Sensor Based on Multi-Walled Carbon Nanotube Thin Films

International Nuclear Information System (INIS)

Cao, C.L.; Hu, C.G.; Fang, L.; Wang, S.X.; Cao, C.L.; Tian, Y.S.; Pan, C.Y.

2009-01-01

The properties of the humidity sensors made of chemically treated and untreated multi-walled carbon nano tube (MWCNT) thin films are investigated systematically. It shows that both the chemically treated and untreated MWCNT thin films demonstrate humidity sensitive properties, but the former have stronger sensitivity than the latter. In the range of 11%-98% relative humidity (RH), the resistances of the chemically treated and untreated MWCNT humidity sensors increase 120% and 28%, respectively. Moreover, the treated humidity sensors showed higher sensitivity and better stability. In addition, the response and recover properties, and stabilization of the humidity sensors are measured, and the humidity sensitive mechanisms of the sensors are analyzed. The humidity sensitivity of carbon nano tube thin films indicates it promise as a kind of humidity sensitive material

Effect of humidity on thoron adsorption in activated charcoal bed

International Nuclear Information System (INIS)

Sudeep Kumara, K.; Karunakara, N.; Yashodhara, I.; Sapra, B.K.; Sahoo, B.K.; Gaware, J.J.; Kanse, S.D.; Mayya, Y.S.

2014-01-01

Activated charcoal is a well-known adsorber of 222 Rn and 220 Rn gases. This property can be effectively used for remediation of these gases in the workplaces of uranium and thorium processing facilities. However, the adsorption on charcoal is sensitive to variation in temperature and humidity. The successful designing and characterization of adsorption systems require an adequate understanding of these sensitivities. The study has been carried out towards this end, to delineate the effect of relative humidity on the efficacy of 220 Rn mitigations in a charcoal bed. Air carrying 220 Rn from a Pylon source was passed through a column filled with coconut shell-based granular activated charcoal. The relative humidity of the air was controlled, and the transmission characteristics were examined at relative humidity varying from 45% to 60%. The mitigation factor was found to decrease significantly with an increase of humidity in the air. (author)

Influence of Wind Strength and Duration on Relative Hypoxia Reductions by Opposite Wind Directions in an Estuary with an Asymmetric Channel

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Ping Wang

2016-09-01

Full Text Available Computer model experiments are applied to analyze hypoxia reductions for opposing wind directions under various speeds and durations in the north–south oriented, two-layer-circulated Chesapeake estuary. Wind’s role in destratification is the main mechanism in short-term reduction of hypoxia. Hypoxia can also be reduced by wind-enhanced estuarine circulation associated with winds that have down-estuary straining components that promote bottom-returned oxygen-rich seawater intrusion. The up-bay-ward along-channel component of straining by the southerly or easterly wind induces greater destratification than the down-bay-ward straining by the opposite wind direction, i.e., northerly or westerly winds. While under the modulation of the west-skewed asymmetric cross-channel bathymetry in the Bay’s hypoxic zone, the westward cross-channel straining by easterly or northerly winds causes greater destratification than its opposite wind direction. The wind-induced cross-channel circulation can be completed much more rapidly than the wind-induced along-channel circulation, and the former is usually more effective than the latter in destratification and hypoxia reduction in an early wind period. The relative importance of cross-channel versus along-channel circulation for a particular wind direction can change with wind speed and duration. The existence of month-long prevailing unidirectional winds in the Chesapeake is explored, and the relative hypoxia reductions among different prevailing directions are analyzed. Scenarios of wind with intermittent calm or reversing directions on an hourly scale are also simulated and compared.

Temperature, humidity and time., Combined effects on radiochromic film dosimeters

International Nuclear Information System (INIS)

Abdel-Fattah, A.A.; Miller, A.

1996-01-01

The effects of both relative humidity and temperature during irradiation on the dose response of FWT-60-00 and Riso B3 radiochromic film dosimeters have been investigated in the relative humidity (RH) range 11-94% and temperature range 20-60 o C for irradiation by 60 Co photons and 10-MeV electrons. The results show that humidity and temperature cannot be treated as independent variables, rather there appears to be interdependence between absorbed dose, temperature, and humidity. Dose rate does not seem to play a significant role. The dependence of temperature during irradiation is + 0.25 ± 0.1% per o C for the FWT-60-00 dosimeters and +0.5 ± 0.1% per o C for Riso B3 dosimeters at temperatures between 20 and 50 o C and at relative humidities between 20 and 53%. At extreme conditions both with respect to temperature and to humidity, the dosimeters show much stronger dependences. Whenever possible one should use dosimeters sealed in pouches under controlled intermediate humidity conditions (30-50%) or, if that is impractical, one should maintain conditions of calibration as close as possible to the conditions of use. Without that precaution, severe dosimetry errors may result. (author)

INFLUENCE OF TEMPERATURE AND RELATIVE HUMIDITY ON THE STUDDED AGARICUS BLAZEI MURRILL MUSHROOM COMPOST

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Sándor Rózsa

2017-12-01

Full Text Available Almond mushroom, Agaricus blazei Murrill, is the so-called secondary saprophyte, developing on partially processed substrate, in which microorganisms reduced complex ligno-cellulose compounds. Numerous authors have shown that due to the similar life cycle in the cultivation of almond mushroom technologies developed for white button mushroom may be applied. However, almond mushroom requires high temperature and high humidity as well as access to light to form fruiting bodies. In Brazil, due to the advantageous climatic conditions this species is frequently grown outdoors; however, in other countries - mainly due to its high temperature requirements - such cultivation system is risky and may only be successful during very warm summers. In this study, we analyzed four kind of compost studded by Agaricus blazei Murrill mushroom mycelium. We recorded every hour the air and compost temperature and the air relative humidity. The best studded compost was the classical, followed by synthetic and then by the mixt compost.

The influence of oxygen, partial vacuum, temperature, relative humidity combined with gamma radiation on the mosquito, Culex pipiens complex l. I. Effect of exposure to temperature and relative humidity alone.

OpenAIRE

Hafez, Mahmood [محمود حافظ; Abdel-Rahmen, A. M.; Osman, A. Z.; Wakid, A. M.; Hafez, M. K.

1993-01-01

The results revealed that a temperature of 10°C was the most effective temperature on pupal mortality of Culex pipiens complex L. followed by 32°C then 20 and 26°C. There was a gradual increase in pupal mortality with increasing the time of exposure to temperatures. The pupal mortality increased with decreasing the relative humidity levels at the same time of exposure. Exposure for short time periods did not affect significantly the pupal mortality. Increasing the exposure time increased m...

The influence of humidity on the kinetics of local anodic oxidation

International Nuclear Information System (INIS)

BartosIk, M; Skoda, D; Tomanec, O; Kalousek, R; Jansky, P; Zlamal, J; Spousta, J; Sikola, T

2007-01-01

In this paper the influence of relative humidity on fabrication of nanostructures at GaAs (100) surfaces by local anodic oxidation (LAO) is reported. The attention was paid both to the dimensions of oxide nanolines prepared at different relative humidities for tip-surface voltages of 6 - 9 V and tip speeds of 10 - 200 nm/s, and to the profiles corresponding to line trenches (etched in HCl after the nanoxidation). Contrary to the expectations the height and the half-width of oxide nanolines did not increase with relative humidity in the whole interval from 35% to 90%, but for lower relative humidities (< 50%) the lines were comparable in size to those prepared at 90%. However, this was accompanied with instabilities in the oxidation process resulting most probably from enhanced size variations of the water meniscus between the tip and the surface at these low humidities

Influence of humidity on the graphene band gap

International Nuclear Information System (INIS)

Zakaryan, H.A.; Aroutiounian, V.M.

2015-01-01

Influences of the humidity on graphene properties are studied and comparisons of graphene and polymer humidity sensors are carried out. Graphene sensors have remarkable response compare to nanoporous polymer membranes. The resistance of polymer sensors is 150 GOhm and decreases in 7.5 times at 60 per cent of the relative humidity. For graphene, resistance drops 4 times starting from ~100 kOhm. This is connected with the extension of graphene band gap. The reason of this is adsorbed water, which can create defects in the lattice or can transfer charge which depends on relative position of HOMO/LUMO of water and Dirac point of graphene

Cross-Sensitivity Of Aethalometer Measurements To Relative Humidity

Energy Technology Data Exchange (ETDEWEB)

Hannemann, A.; Baltensperger, U.; Weingartner, E.

2005-03-01

Absorptive light reduction by atmospheric aerosols is important with respect to their climate forcing. An instrument to measure light absorption is the aethalometer, which is routinely used to measure the attenuation of light transmitted through aerosol-laden fibre filters. Measurements have shown that the condensable gases require a correction for artefacts. We present the first corrections for hydrophobic Palas soot-laden filters for the whole humidity range, enhancing the accuracy of aethalometer datasets. (author)

Determination of partition and diffusion coefficient of formaldehyde in selected building materials and impact of relative humidity

Science.gov (United States)

The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, "green" gypsum wallboard, and "green" carpet) under three relative humidity (RH) conditions (20%, 50% and 70% RH). A dynamic dual-chamber test meth...

Water sorption in wood and modified wood at high values of relative humidity

DEFF Research Database (Denmark)

Engelund, Emil Tang; Thygesen, Lisbeth Garbrecht; Hoffmeyer, Preben

2010-01-01

A theoretical study of the amount of moisture held in wood as capillary condensed water in the relative humidity (RH) range of 90–99.9% is carried out. The study is based on idealized geometries of the softwood structure related to micrographs. It is confined to structural elements such as bordered......, and different degrees of pit aspiration are assigned to earlywood and latewood. We suggest based on the results that capillary condensation makes only a very small contribution to the equilibrium moisture content. At 99.9% RH the contribution amounts to less than 0.0035 kg water per kg dry wood. This is in line...

Ground-level climate at a peatland wind farm in Scotland is affected by wind turbine operation

Science.gov (United States)

Armstrong, Alona; Burton, Ralph R.; Lee, Susan E.; Mobbs, Stephen; Ostle, Nicholas; Smith, Victoria; Waldron, Susan; Whitaker, Jeanette

2016-04-01

The global drive to produce low-carbon energy has resulted in an unprecedented deployment of onshore wind turbines, representing a significant land use change for wind energy generation with uncertain consequences for local climatic conditions and the regulation of ecosystem processes. Here, we present high-resolution data from a wind farm collected during operational and idle periods that shows the wind farm affected several measures of ground-level climate. Specifically, we discovered that operational wind turbines raised air temperature by 0.18 °C and absolute humidity (AH) by 0.03 g m-3 during the night, and increased the variability in air, surface and soil temperature throughout the diurnal cycle. Further, the microclimatic influence of turbines on air temperature and AH decreased logarithmically with distance from the nearest turbine. These effects on ground-level microclimate, including soil temperature, have uncertain implications for biogeochemical processes and ecosystem carbon cycling, including soil carbon stocks. Consequently, understanding needs to be improved to determine the overall carbon balance of wind energy.

Investigations of microelectronic humidity sensors made of composite oxides thin films

International Nuclear Information System (INIS)

Pogossyan, A.S.; Arutyunyan, V.M.

1996-01-01

Basic characteristics (the moisture sensitivity, lag, hysteresis and stability) of humidity sensors made of Fe 2 O 3 thin films with different K 2 content, as well as CaSiO 3 and NaBiTi 2 O 6 films,-new materials for the humidity sensors, are investigated. A composition Fe 2 O 3 (K) is found to be optimal with respect to high moisture sensitivity, speed of response, and a linearity in a wide range of the relative humidity. A mechanism of the moisture-sensitivity of films investigated is discussed. Criteria for the design parameters of the high-impedance humidity sensors are defined with the aim to broadening of the working range of the relative humidity in a side way of low values of the humidity.10 refs

Humidity effects on wire insulation breakdown strength.

Energy Technology Data Exchange (ETDEWEB)

Appelhans, Leah

2013-08-01

Methods for the testing of the dielectric breakdown strength of insulation on metal wires under variable humidity conditions were developed. Two methods, an ASTM method and the twisted pair method, were compared to determine if the twisted pair method could be used for determination of breakdown strength under variable humidity conditions. It was concluded that, although there were small differences in outcomes between the two testing methods, the non-standard method (twisted pair) would be appropriate to use for further testing of the effects of humidity on breakdown performance. The dielectric breakdown strength of 34G copper wire insulated with double layer Poly-Thermaleze/Polyamide-imide insulation was measured using the twisted pair method under a variety of relative humidity (RH) conditions and exposure times. Humidity at 50% RH and below was not found to affect the dielectric breakdown strength. At 80% RH the dielectric breakdown strength was significantly diminished. No effect for exposure time up to 140 hours was observed at 50 or 80%RH.

Defining relative humidity in terms of water activity. Part 1: definition

Science.gov (United States)

Feistel, Rainer; Lovell-Smith, Jeremy W.

2017-08-01

Relative humidity (RH) is a quantity widely used in various fields such as metrology, meteorology, climatology or engineering. However, RH is neither uniformly defined, nor do some definitions properly account for deviations from ideal-gas properties, nor is the application range of interest fully covered. In this paper, a new full-range definition of RH is proposed that is based on the thermodynamics of activities in order to include deviations from ideal-gas behaviour. Below the critical point of pure water, at pressures p  definition is consistent with de-facto standard RH definitions published previously and recommended internationally. Virial approximations are reported for estimating small corrections to the ideal-gas equations.

All-Optical Graphene Oxide Humidity Sensors

Directory of Open Access Journals (Sweden)

Weng Hong Lim

2014-12-01

Full Text Available The optical characteristics of graphene oxide (GO were explored to design and fabricate a GO-based optical humidity sensor. GO film was coated onto a SU8 polymer channel waveguide using the drop-casting technique. The proposed sensor shows a high TE-mode absorption at 1550 nm. Due to the dependence of the dielectric properties of the GO film on water content, this high TE-mode absorption decreases when the ambient relative humidity increases. The proposed sensor shows a rapid response (<1 s to periodically interrupted humid air flow. The transmission of the proposed sensor shows a linear response of 0.553 dB/% RH in the range of 60% to 100% RH.

All-optical graphene oxide humidity sensors.

Science.gov (United States)

Lim, Weng Hong; Yap, Yuen Kiat; Chong, Wu Yi; Ahmad, Harith

2014-12-17

The optical characteristics of graphene oxide (GO) were explored to design and fabricate a GO-based optical humidity sensor. GO film was coated onto a SU8 polymer channel waveguide using the drop-casting technique. The proposed sensor shows a high TE-mode absorption at 1550 nm. Due to the dependence of the dielectric properties of the GO film on water content, this high TE-mode absorption decreases when the ambient relative humidity increases. The proposed sensor shows a rapid response (<1 s) to periodically interrupted humid air flow. The transmission of the proposed sensor shows a linear response of 0.553 dB/% RH in the range of 60% to 100% RH.

A high sensitivity nanomaterial based SAW humidity sensor

Energy Technology Data Exchange (ETDEWEB)

Wu, T-T; Chou, T-H [Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan (China); Chen, Y-Y [Department of Mechanical Engineering, Tatung University, Taipei 104, Taiwan (China)], E-mail: wutt@ndt.iam.ntu.edu.tw

2008-04-21

In this paper, a highly sensitive humidity sensor is reported. The humidity sensor is configured by a 128{sup 0}YX-LiNbO{sub 3} based surface acoustic wave (SAW) resonator whose operating frequency is at 145 MHz. A dual delay line configuration is realized to eliminate external temperature fluctuations. Moreover, for nanostructured materials possessing high surface-to-volume ratio, large penetration depth and fast charge diffusion rate, camphor sulfonic acid doped polyaniline (PANI) nanofibres are synthesized by the interfacial polymerization method and further deposited on the SAW resonator as selective coating to enhance sensitivity. The humidity sensor is used to measure various relative humidities in the range 5-90% at room temperature. Results show that the PANI nanofibre based SAW humidity sensor exhibits excellent sensitivity and short-term repeatability.

Empirical model for estimating dengue incidence using temperature, rainfall, and relative humidity: a 19-year retrospective analysis in East Delhi.

Science.gov (United States)

Ramachandran, Vishnampettai G; Roy, Priyamvada; Das, Shukla; Mogha, Narendra Singh; Bansal, Ajay Kumar

2016-01-01

Aedes mosquitoes are responsible for transmitting the dengue virus. The mosquito lifecycle is known to be influenced by temperature, rainfall, and relative humidity. This retrospective study was planned to investigate whether climatic factors could be used to predict the occurrence of dengue in East Delhi. The number of monthly dengue cases reported over 19 years was obtained from the laboratory records of our institution. Monthly data of rainfall, temperature, and humidity collected from a local weather station were correlated with the number of monthly reported dengue cases. One-way analysis of variance was used to analyse whether the climatic parameters differed significantly among seasons. Four models were developed using negative binomial generalized linear model analysis. Monthly rainfall, temperature, humidity, were used as independent variables, and the number of dengue cases reported monthly was used as the dependent variable. The first model considered data from the same month, while the other three models involved incorporating data with a lag phase of 1, 2, and 3 months, respectively. The greatest number of cases was reported during the post-monsoon period each year. Temperature, rainfall, and humidity varied significantly across the pre-monsoon, monsoon, and post-monsoon periods. The best correlation between these three climatic factors and dengue occurrence was at a time lag of 2 months. This study found that temperature, rainfall, and relative humidity significantly affected dengue occurrence in East Delhi. This weather-based dengue empirical model can forecast potential outbreaks 2-month in advance, providing an early warning system for intensifying dengue control measures.

Study on radon concentration monitoring using activated charcoal canisters in high humidity environments

International Nuclear Information System (INIS)

Wang Yuexing; Wang Haijun; Yang Yifang; Qin Sichang; Wang Zhentao; Zhang Zhenjiang

2009-01-01

The effects of humidity on the sensitivity using activated charcoal canisters for measuring radon concentrations in high humidity environments were studied. Every canister filled with 80 g of activated charcoal, and they were exposed to 48 h or 72 h in the relative humidity of 68%, 80%, 88% and 96% (28 degree C), respectively. The amount of radon absorbed in the canisters was determined by counting the gamma rays from 214 Pb and 214 Bi (radon progeny). The results showed that counts decreased with the increase of relative humidity. There was a negative linear relationship between count and humidity. In the relative humidity range of 68%-96%, the sensitivity of radon absorption decreased about 2.4% for every 1% (degree)rise in humidity. The results also showed that the exposure time of the activated charcoal canisters should be less than 3 days. (authors)

Relationships of relative humidity with PM2.5 and PM10 in the Yangtze River Delta, China.

Science.gov (United States)

Lou, Cairong; Liu, Hongyu; Li, Yufeng; Peng, Yan; Wang, Juan; Dai, Lingjun

2017-10-23

Severe particulate matter (PM, including PM 2.5 and PM 10 ) pollution frequently impacts many cities in the Yangtze River Delta (YRD) in China, which has aroused growing concern. In this study, we examined the associations between relative humidity (RH) and PM pollution using the equal step-size statistical method. Our results revealed that RH had an inverted U-shaped relationship with PM 2.5 concentrations (peaking at RH = 45-70%), and an inverted V-shaped relationship (peaking at RH = 40 ± 5%) with PM 10 , SO 2 , and NO 2 . The trends of polluted-day number significantly changed at RH = 70%. The very-dry (RH humidity (RH = 60-70%) conditions positively affected PM 2.5 and exerted an accumulation effect, while the mid-humidity (RH = 70-80%), high-humidity (RH = 80-90%), and extreme-humidity (RH = 90-100%) conditions played a significant role in reducing particle concentrations. For PM 10 , the accumulation and reduction effects of RH were split at RH = 45%. Moreover, an upward slope in the PM 2.5 /PM 10 ratio indicated that the accumulation effects from increasing RH were more intense on PM 2.5 than on PM 10 , while the opposite was noticed for the reduction effects. Secondary transformations from SO 2 and NO 2 to sulfate and nitrate were mainly responsible for PM 2.5 pollution, and thus, controlling these precursors is effective in mitigating the PM pollution in the YRD, especially during winter. The conclusions in this study will be helpful for regional air-quality management.

Impacts of Present and Future Climate Variability On Agriculture and Forestry in the Humid and Sub-Humid Tropics

International Nuclear Information System (INIS)

Zhao, Y.; Wang, C.; Wang, S.; Tibig, Lourdes V.

2005-01-01

Although there are different results from different studies, most assessments indicate that climate variability would have negative effects on agriculture and forestry in the humid and sub-humid tropics. Cereal crop yields would decrease generally with even minimal increases in temperature. For commercial crops, extreme events such as cyclones, droughts and floods lead to larger damages than only changes of mean climate. Impacts of climate variability on livestock mainly include two aspects; impacts on animals such as increase of heat and disease stress-related death, and impacts on pasture. As to forestry, climate variability would have negative as well as some positive impacts on forests of humid and sub-humid tropics. However, in most tropical regions, the impacts of human activities such as deforestation will be more important than climate variability and climate change in determining natural forest cover

Effect of fabric texture and material on perceived discomfort at high humidity

DEFF Research Database (Denmark)

Toftum, Jørn; Rasmussen, Leif W.; Mackeprang, Jørgen

1999-01-01

This study investigated the effect of material (cotton/polyester) and texture (woven/knitted) of the inner layer of a clothing ensemble on human discomfort at high skin humidity. No clear effect on discomfort of material and texture could be detected. However, acceptability of skin humidity de......-crea-sed with increasing relative skin humidity. A model was developed that predicts the percentage of persons dissatisfied due to humid skin as a function of relative skin humidity. The model applies for woven and knitted cot-ton and polyester materials and for activity levels typical for office work. Even at very high...

Self-calibrated humidity sensor in CMOS without post-processing.

Science.gov (United States)

Nizhnik, Oleg; Higuchi, Kohei; Maenaka, Kazusuke

2012-01-01

A 1.1 μW power dissipation, voltage-output humidity sensor with 10% relative humidity accuracy was developed in the LFoundry 0.15 μm CMOS technology without post-processing. The sensor consists of a woven lateral array of electrodes implemented in CMOS top metal, a humidity-sensitive layer of Intervia Photodielectric 8023D-10, a CMOS capacitance to voltage converter, and the self-calibration circuitry.

Self-Calibrated Humidity Sensor in CMOS without Post-Processing

OpenAIRE

Nizhnik, Oleg; Higuchi, Kohei; Maenaka, Kazusuke

2011-01-01

A 1.1 μW power dissipation, voltage-output humidity sensor with 10% relative humidity accuracy was developed in the LFoundry 0.15 μm CMOS technology without post-processing. The sensor consists of a woven lateral array of electrodes implemented in CMOS top metal, a humidity-sensitive layer of Intervia Photodielectric 8023D-10, a CMOS capacitance to voltage converter, and the self-calibration circuitry.

Effect of humidity and interlayer cation on frictional strength of montmorillonite

Science.gov (United States)

Tetsuka, H.; Katayama, I.; Sakuma, H.; Tamura, K.

2016-12-01

Smectite has been ubiquitously seen in fault gouge (Schleicher et al., 2006; Kuo et al., 2009; Si et al., 2014; Kameda, 2015) and is characteristic by low frictional coefficient (Saffer et al., 2001; Ikari et al., 2007); consequently, it has a key role in fault dynamics. The frictional strength of montmorillonite (a typical type of smectite) is affected by mainly two factors, 1) hydration state and 2) interlayer cation. Previous laboratory experiments have shown that the frictional strength of montmorillonite changes with hydration state (Ikari et al., 2007) and with interlayer cation (Behnsen and Faulkner, 2013). However, experimental study for frictional strengths of interlayer cation-exchanged montmorillonite under controlled hydration state has not been reported. We are developing humidity control system in biaxial friction testing machine and try to investigate the effect of relative humidity and interlayer cation on frictional strength of montmorillonite. The humidity control system consists of two units, 1) the pressure vessel (core holder) unit controlled by a constant temperature and 2) the vapor generating unit controlled by variable temperature. We control relative humidity around sample, which is calculated from the temperature around sample and the vapor pressure at vapor generating unit. Preliminary experiments under controlled humidity show frictional coefficient of montmorillonite decrease with increasing relative humidity. In the meeting, we will report the systematic study of frictional coefficient as function of relative humidity and interlayer cation species.

Effects of atmospheric humidity on uptake of elemental iodine by plants

International Nuclear Information System (INIS)

Angeletti, L.; Guenot, J.; Caput, C.

1983-01-01

A laboratory study was performed under controlled experimental conditions in order to evaluate the effects of the relative humidity and the exposure time on the velocity of deposition of vapour iodine onto aerials parts of plants. The results show that: - the deposition velocity increases by a factor of 2 for each increase of relative humidity of 25%, - the deposition velocity is independent of the exposure time. The foliar uptake of vapour iodine seems to be related both to stomatal opening and cuticular sorption. The importance of cuticular sorption increases rapidly with the relative humidity [fr

Effect of relative humidity on lipid oxidation in freezedried emulsions

Directory of Open Access Journals (Sweden)

Chinachoti, P.

2000-10-01

Full Text Available Oxidative stability was studied in a freeze-dried emulsion consisting of linoleic acid (LA, Tween-20, sucrose and maltodextrin in the presence of a catalyst (FeSO4/ascorbic acid. Changes in residual LA and conjugated dienes as a function of time were monitored at 0, 32, 43 and 75% relative humidities (RH. Based on GC analyses, LA oxidation was more significant in the surface fraction than the entrapped. The loss of surface oil upon storage may also be due to partial entrapment. However faster oxidation of the surface oil was confirmed by measurement of diene conjugation. Oxidation was more rapid at the lower relative humidities (0 and 32% RH and decreased with increasing RH. At high moisture, physical modifications in the sample were observed, including reduced porosity, structural collapse, reduction of the surface oil and coalescence of oil droplets triggered by sucrose crystallization. These may be responsible for the decreased oxidation. Sucrose crystallization at the higher humidities inhibited oxidation. In addition, while samples with similar glass transition temperature (Tg range behaved differently, samples with different glass transition range showed similar oxidative behaviour. Microstructural changes leading to oil entrapment and oil droplet coalescence were found to be significant, in this case.Se ha estudiado la estabilidad oxidativa en una emulsión liofilizada compuesta de ácido linoleico (LA, Tween-20, sacarosa y maltodextrina en presencia de un catalizador (FeSO4/ácido ascórbico. Los cambios en ácido linoleico remanente (LA y dienos conjugados en función del tiempo fueron monitorizados a humedades relativas (RH del 0, 32, 43 y 75%. Basado en análisis por cromatografía gaseosa, la oxidación de LA fue más significativa en la fracción superficial que en la encapsulada. La pérdida de aceite superficial con el almacenamiento puede deberse también al encapsulado parcial. Sin embargo, la más rápida oxidación del aceite

Anomalous water expulsion from carbon-based rods at high humidity

Science.gov (United States)

Nune, Satish K.; Lao, David B.; Heldebrant, David J.; Liu, Jian; Olszta, Matthew J.; Kukkadapu, Ravi K.; Gordon, Lyle M.; Nandasiri, Manjula I.; Whyatt, Greg; Clayton, Chris; Gotthold, David W.; Engelhard, Mark H.; Schaef, Herbert T.

2016-09-01

Three water adsorption-desorption mechanisms are common in inorganic materials: chemisorption, which can lead to the modification of the first coordination sphere; simple adsorption, which is reversible; and condensation, which is irreversible. Regardless of the sorption mechanism, all known materials exhibit an isotherm in which the quantity of water adsorbed increases with an increase in relative humidity. Here, we show that carbon-based rods can adsorb water at low humidity and spontaneously expel about half of the adsorbed water when the relative humidity exceeds a 50-80% threshold. The water expulsion is reversible, and is attributed to the interfacial forces between the confined rod surfaces. At wide rod spacings, a monolayer of water can form on the surface of the carbon-based rods, which subsequently leads to condensation in the confined space between adjacent rods. As the relative humidity increases, adjacent rods (confining surfaces) in the bundles are drawn closer together via capillary forces. At high relative humidity, and once the size of the confining surfaces has decreased to a critical length, a surface-induced evaporation phenomenon known as solvent cavitation occurs and water that had condensed inside the confined area is released as a vapour.

Surface-type humidity sensor based on cellulose-PEPC for telemetry systems

International Nuclear Information System (INIS)

Karimov, Kh. S.; Saleem, M.; Qasuria, T. A.; Farooq, M.

2011-01-01

Au/cellulose-PEPC/Au surface-type humidity sensors were fabricated by drop-casting cellulose and poly-N-epoxypropylcarbazole (PEPC) blend thin films. A blend of 2wt% of each cellulose and PEPC in benzol was used for the deposition of humidity sensing films. Blend films were deposited on glass substrates with preliminary deposited surface-type gold electrodes. Films of different thicknesses of cellulose and PEPC composite were deposited by drop-casting technique. A change in electrical resistance and capacitance of the fabricated devices was observed by increasing the relative humidity in the range of 0-95% RH. It was observed that the capacitances of the sensors increase, while their resistances decrease with increasing the relative humidity. The sensors were connected to op-amp square wave oscillators. It was observed that with increasing the relative humidity, the oscillator's frequencies were also increased in the range of 4.2-12.0 kHz for 65 μm thick film sample, 4.1-9.0 kHz for 88 μm thick film sample, and 4.2-9.0 kHz for 210 μm sample. Effects of film thickness on the oscillator's frequency with respect to humidity were also investigated. This polymer humidity sensor controlled oscillator can be used for short-range and long-range remote systems at environmental monitoring and assessment of the humidity level. (semiconductor integrated circuits)

Humidity Detection Using Metal Organic Framework Coated on QCM

KAUST Repository

Kosuru, Lakshmoji; Bouchaala, Adam M.; Jaber, Nizar; Younis, Mohammad I.

2016-01-01

of a quartz crystal microbalance. The resonance frequencies of these sensors with varying relative humidity (RH) from 22% RH to 69% RH are measured using impedance analysis method. The sensitivity, humidity hysteresis, response, and recovery times

The effects of temperature, relative humidity, light, and resource quality on flight initiation in the red flour beetle, Tribolium castaneum.

Science.gov (United States)

Drury, Douglas W; Whitesell, Matthew E; Wade, Michael J

2016-03-01

We investigated the environmental conditions that induce a flight response in the red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), including resource quality, temperature, relative humidity, and light. Over 72-h trial periods, we observed the proportion of individuals emigrating by flight to range from 0.0 in extreme heat or cold to 0.82 with starvation. Resource quality, presence of a light source, and temperature all directly influenced the initiation of the flight response. We did not detect any effect of relative humidity or sudden change in temperature on the incidence of flight. We discuss our findings in the context of Tribolium ecology and evolution.

Influence of the relative humidity and the temperature on the in-vivo friction behaviour of human skin

NARCIS (Netherlands)

Klaassen, M.; Schipper, D. J.; Masen, M.A.

2016-01-01

Both temperature and relative humidity are known to influence the frictional behaviour of human skin. However, literature does not completely cover to what extent both parameters play a role. Measurements were conducted using an in-house built reciprocating tribometer inside an enclosure in which

Fabrication and Characterization of a CMOS-MEMS Humidity Sensor

Science.gov (United States)

Dennis, John-Ojur; Ahmed, Abdelaziz-Yousif; Khir, Mohd-Haris

2015-01-01

This paper reports on the fabrication and characterization of a Complementary Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) device with embedded microheater operated at relatively elevated temperatures (40 °C to 80 °C) for the purpose of relative humidity measurement. The sensing principle is based on the change in amplitude of the device due to adsorption or desorption of humidity on the active material layer of titanium dioxide (TiO2) nanoparticles deposited on the moving plate, which results in changes in the mass of the device. The sensor has been designed and fabricated through a standard 0.35 µm CMOS process technology and post-CMOS micromachining technique has been successfully implemented to release the MEMS structures. The sensor is operated in the dynamic mode using electrothermal actuation and the output signal measured using a piezoresistive (PZR) sensor connected in a Wheatstone bridge circuit. The output voltage of the humidity sensor increases from 0.585 mV to 30.580 mV as the humidity increases from 35% RH to 95% RH. The output voltage is found to be linear from 0.585 mV to 3.250 mV as the humidity increased from 35% RH to 60% RH, with sensitivity of 0.107 mV/% RH; and again linear from 3.250 mV to 30.580 mV as the humidity level increases from 60% RH to 95% RH, with higher sensitivity of 0.781 mV/% RH. On the other hand, the sensitivity of the humidity sensor increases linearly from 0.102 mV/% RH to 0.501 mV/% RH with increase in the temperature from 40 °C to 80 °C and a maximum hysteresis of 0.87% RH is found at a relative humidity of 80%. The sensitivity is also frequency dependent, increasing from 0.500 mV/% RH at 2 Hz to reach a maximum value of 1.634 mV/% RH at a frequency of 12 Hz, then decreasing to 1.110 mV/% RH at a frequency of 20 Hz. Finally, the CMOS-MEMS humidity sensor showed comparable response, recovery, and repeatability of measurements in three cycles as compared to a standard sensor that directly

Fabrication and Characterization of a CMOS-MEMS Humidity Sensor.

Science.gov (United States)

Dennis, John-Ojur; Ahmed, Abdelaziz-Yousif; Khir, Mohd-Haris

2015-07-10

This paper reports on the fabrication and characterization of a Complementary Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) device with embedded microheater operated at relatively elevated temperatures (40 °C to 80 °C) for the purpose of relative humidity measurement. The sensing principle is based on the change in amplitude of the device due to adsorption or desorption of humidity on the active material layer of titanium dioxide (TiO2) nanoparticles deposited on the moving plate, which results in changes in the mass of the device. The sensor has been designed and fabricated through a standard 0.35 µm CMOS process technology and post-CMOS micromachining technique has been successfully implemented to release the MEMS structures. The sensor is operated in the dynamic mode using electrothermal actuation and the output signal measured using a piezoresistive (PZR) sensor connected in a Wheatstone bridge circuit. The output voltage of the humidity sensor increases from 0.585 mV to 30.580 mV as the humidity increases from 35% RH to 95% RH. The output voltage is found to be linear from 0.585 mV to 3.250 mV as the humidity increased from 35% RH to 60% RH, with sensitivity of 0.107 mV/% RH; and again linear from 3.250 mV to 30.580 mV as the humidity level increases from 60% RH to 95% RH, with higher sensitivity of 0.781 mV/% RH. On the other hand, the sensitivity of the humidity sensor increases linearly from 0.102 mV/% RH to 0.501 mV/% RH with increase in the temperature from 40 °C to 80 °C and a maximum hysteresis of 0.87% RH is found at a relative humidity of 80%. The sensitivity is also frequency dependent, increasing from 0.500 mV/% RH at 2 Hz to reach a maximum value of 1.634 mV/% RH at a frequency of 12 Hz, then decreasing to 1.110 mV/% RH at a frequency of 20 Hz. Finally, the CMOS-MEMS humidity sensor showed comparable response, recovery, and repeatability of measurements in three cycles as compared to a standard sensor that directly

Multi-channel fiber optic dew and humidity sensor

Science.gov (United States)

Limodehi, Hamid E.; Mozafari, Morteza; Amiri, Hesam; Légaré, François

2018-03-01

In this article, we introduce a multi-channel fiber optic dew and humidity sensor which works using a novel method based on relation between surface plasmon resonance (SPR) and water vapor condensation. The proposed sensor can instantly detect moisture or dew formation through its fiber optic channels, separately situated in different places. It enables to simultaneously measure the ambient Relative Humidity (RH) and dew point temperature of several environments with accuracy of 5%.

Building America Case Study: Energy Efficient Management of Mechanical Ventilation and Relative Humidity in Hot-Humid Climates, Cocoa, Florida

Energy Technology Data Exchange (ETDEWEB)

2017-01-01

In hot and humid climates, it is challenging to energy-efficiently maintain indoor RH at acceptable levels while simultaneously providing required ventilation, particularly in high performance low cooling load homes. The fundamental problem with solely relying on fixed capacity central cooling systems to manage moisture during low sensible load periods is that they are oversized for cooler periods of the year despite being 'properly sized' for a very hot design cooling day. The primary goals of this project were to determine the impact of supplementing a central space conditioning system with 1) a supplemental dehumidifier and 2) a ductless mini-split on seasonal energy use and summer peak power use as well as the impact on thermal distribution and humidity control inside a completely furnished lab home that was continuously ventilated in accordance with ASHRAE 62.2-2013.

A dual-biomarker approach for quantification of changes in relative humidity from sedimentary lipid D∕H ratios

Directory of Open Access Journals (Sweden)

O. Rach

2017-07-01

Full Text Available Past climatic change can be reconstructed from sedimentary archives by a number of proxies. However, few methods exist to directly estimate hydrological changes and even fewer result in quantitative data, impeding our understanding of the timing, magnitude and mechanisms of hydrological changes. Here we present a novel approach based on δ2H values of sedimentary lipid biomarkers in combination with plant physiological modeling to extract quantitative information on past changes in relative humidity. Our initial application to an annually laminated lacustrine sediment sequence from western Europe deposited during the Younger Dryas cold period revealed relative humidity changes of up to 15 % over sub-centennial timescales, leading to major ecosystem changes, in agreement with palynological data from the region. We show that by combining organic geochemical methods and mechanistic plant physiological models on well characterized lacustrine archives it is possible to extract quantitative ecohydrological parameters from sedimentary lipid biomarker δ2H data.

Effect of humidity on the filter pressure drop

International Nuclear Information System (INIS)

Vendel, J.; Letourneau, P.

1995-01-01

The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO 2 ). Cesium hydroxyde (CsOH) of size of 2 μ M AMMD has been generated by an ultrasonic generator and the 0.7 μm AMMD titanium oxyde has been dispersed by a open-quotes turn-tableclose quotes generator. As it is noted in the BISWAS'publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced

Effect of humidity on the filter pressure drop

Energy Technology Data Exchange (ETDEWEB)

Vendel, J.; Letourneau, P. [Institut de Protection et de Surete Nucleaire, Gif-sur-Yvette (France)

1995-02-01

The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO{sub 2}). Cesium hydroxyde (CsOH) of size of 2 {mu} M AMMD has been generated by an ultrasonic generator and the 0.7 {mu}m AMMD titanium oxyde has been dispersed by a {open_quotes}turn-table{close_quotes} generator. As it is noted in the BISWAS`publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced.

Results of the Phoenix Relative Humidity Sensor Recalibration

Science.gov (United States)

Martinez, G.; Fischer, E.; Renno, N. O.

2017-12-01

We show results of the recalibration of the Thermal and Electrical Conductivity Probe (TECP) relative humidity (RH) sensor of the Phoenix Mars lander [Zent et al., 2009]. Due to uncertainties in its pre-flight calibration, which partially overlapped the environmental conditions found at the Phoenix landing site [Tamppari et al., 2010], only the raw, unprocessed output of the TECP RH sensor is available in NASA's Planetary Data System (PDS). The sensor's calibration was revised in 2016 to correct for inaccuracies at the lowest temperatures [Zent et al., 2016], but the new processed RH values were not posted in the PDS. We have been using a spare engineering unit of the TECP to recalibrate the sensor in the full range of Phoenix landing site conditions in the Michigan Mars Environmental Chamber (MMEC) [Fischer et al., 2016]. We compare raw output data of the engineering unit in the MMEC with that of the flight unit from the preflight calibration. We observed that the engineering unit's RH sensor output was shifted to higher values compared to the flight unit's output at the same conditions of temperature and humidity. Based on this shift, we use a translation function that fits the in-situ measurements of the flight unit into the engineering unit output space. To improve the accuracy of this function, we use additional observations corresponding to saturated conditions when near-surface fog was observed [Whiteway et al., 2009], as well as observations around noon when the RH is expected to be below 5%. The entire range of conditions observed on the Martian surface is covered in our recalibration. The raw output of the sensor is used to obtain a new calibration function. This allows us to obtain high-level RH data at Martian polar conditions. The recalibrated data will be posted in the PDS. REFERENCES: Fischer, E., et al. (2016), Astrobiology, 16, 12, doi: 10.1089/ast.2016.1525. Tamppari, L. K., et al. (2010), J. Geophys. Res., 115, E00E17, doi:10.1029/2009JE003415

Determination of partition and diffusion coefficients of formaldehyde in selected building materials and impact of relative humidity (journal)

Science.gov (United States)

The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, "green" gypsum wallboard, and "green" carpet) under three relative humidity (RH) conditions (20%, 50% and 70% RH). A dynamic dual-chamber test meth...

Development of La3+ Doped CeO2 Thick Film Humidity Sensors

Directory of Open Access Journals (Sweden)

Chunjie Wang

2014-01-01

Full Text Available The humidity sensitive characteristics of the sensor fabricated from 10 mol% La2O3 doped CeO2 nanopowders with particle size 17.26 nm synthesized via hydrothermal method were investigated at different frequencies. It was found that the sensor shows high humidity sensitivity, rapid response-recovery characteristics, and narrow hysteresis loop at 100 Hz in the relative humidity range from 11% to 95%. The impedance of the sensor decreases by about five orders of magnitude as relative humidity increases. The maximum humidity hysteresis is about 6% RH, and the response and recovery time is 12 and 13 s, respectively. These results indicate that the nanosized La2O3 doped CeO2 powder has potential application as high-performance humidity sensor.

A CMOS Humidity Sensor for Passive RFID Sensing Applications

Directory of Open Access Journals (Sweden)

Fangming Deng

2014-05-01

Full Text Available This paper presents a low-cost low-power CMOS humidity sensor for passive RFID sensing applications. The humidity sensing element is implemented in standard CMOS technology without any further post-processing, which results in low fabrication costs. The interface of this humidity sensor employs a PLL-based architecture transferring sensor signal processing from the voltage domain to the frequency domain. Therefore this architecture allows the use of a fully digital circuit, which can operate on ultra-low supply voltage and thus achieves low-power consumption. The proposed humidity sensor has been fabricated in the TSMC 0.18 μm CMOS process. The measurements show this humidity sensor exhibits excellent linearity and stability within the relative humidity range. The sensor interface circuit consumes only 1.05 µW at 0.5 V supply voltage and reduces it at least by an order of magnitude compared to previous designs.

A CMOS Humidity Sensor for Passive RFID Sensing Applications

Science.gov (United States)

Deng, Fangming; He, Yigang; Zhang, Chaolong; Feng, Wei

2014-01-01

This paper presents a low-cost low-power CMOS humidity sensor for passive RFID sensing applications. The humidity sensing element is implemented in standard CMOS technology without any further post-processing, which results in low fabrication costs. The interface of this humidity sensor employs a PLL-based architecture transferring sensor signal processing from the voltage domain to the frequency domain. Therefore this architecture allows the use of a fully digital circuit, which can operate on ultra-low supply voltage and thus achieves low-power consumption. The proposed humidity sensor has been fabricated in the TSMC 0.18 μm CMOS process. The measurements show this humidity sensor exhibits excellent linearity and stability within the relative humidity range. The sensor interface circuit consumes only 1.05 μW at 0.5 V supply voltage and reduces it at least by an order of magnitude compared to previous designs. PMID:24841250

A CMOS humidity sensor for passive RFID sensing applications.

Science.gov (United States)

Deng, Fangming; He, Yigang; Zhang, Chaolong; Feng, Wei

2014-05-16

This paper presents a low-cost low-power CMOS humidity sensor for passive RFID sensing applications. The humidity sensing element is implemented in standard CMOS technology without any further post-processing, which results in low fabrication costs. The interface of this humidity sensor employs a PLL-based architecture transferring sensor signal processing from the voltage domain to the frequency domain. Therefore this architecture allows the use of a fully digital circuit, which can operate on ultra-low supply voltage and thus achieves low-power consumption. The proposed humidity sensor has been fabricated in the TSMC 0.18 μm CMOS process. The measurements show this humidity sensor exhibits excellent linearity and stability within the relative humidity range. The sensor interface circuit consumes only 1.05 µW at 0.5 V supply voltage and reduces it at least by an order of magnitude compared to previous designs.

Effects of air psychrometrics on the exergetic efficiency of a wind farm at a coastal mountainous site – An experimental study

DEFF Research Database (Denmark)

Xydis, George

2012-01-01

In this paper, the most important energy and exergy characteristics of wind energy were examined. Atmospheric variables as air temperature, humidity and pressure and their effects on the wind turbine output were investigated toward wind energy exploitation. It was shown that these usually...

Dynamics of spatial heterogeneity of stomatal closure in Tradescantia virginiana altered by growth at high relative air humidity

NARCIS (Netherlands)

Rezaei Nejad, A.; Harbinson, J.; Meeteren, van U.

2006-01-01

The spatial heterogeneity of stomatal closure in response to rapid desiccation of excised well-watered Tradescantia virginiana leaves grown at moderate (55%) or high (90%) relative air humidity (RH) was studied using a chlorophyll fluorescence imaging system under non-photorespiratory conditions.

Population growth and development of the psocid Liposcelis rufa (Psocoptera: Liposcelididae) at constant temperatures and relative humidities.

Science.gov (United States)

Gautam, S G; Opit, G P; Giles, K L

2010-10-01

We investigated the effects of eight temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, and 40.0 degrees C) and four relative humidities (43, 55, 63, and 75%) on population growth and development of the psocid Liposcelis rufa Broadhead (Psocoptera: Liposcelididae). L. rufa did not survive at 43% RH, at all temperatures tested; at 55% RH, at the highest four temperatures; and at 63% RH and 40.0 degrees C. The greatest population growth was recorded at 35.0 degrees C and 75% RH (73-fold growth). At 40.0 degrees C, L. rufa populations declined or barely grew. L. rufa males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 31, 54, and 15%, respectively. Female L. rufa have two to five instars, and the percentages of females with two, three, four, and five instars were 2, 44, 42, and 12%, respectively. The life cycle was shorter for males than females. We developed temperature-dependent developmental equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages. The ability of L. rufa to reproduce at a relative humidity of 55% and temperatures of 22.5-30.0 degrees C and at relative humidities of 63-75% and temperatures of 22.5-37.5 degrees C, in addition to being able to survive at 40.0 degrees C, suggests that this species would be expected to have a broader distribution than other Liposcelis species. These data provide a better understanding of L. rufa population dynamics and can be used to help develop effective management strategies for this psocid.

Modelling and Control of Ionic Electroactive Polymer Actuators under Varying Humidity Conditions

Directory of Open Access Journals (Sweden)

S. Sunjai Nakshatharan

2018-02-01

Full Text Available In this work, we address the problem of position control of ionic electroactive polymer soft actuators under varying relative humidity conditions. The impact of humidity on the actuation performance of ionic actuators is studied through frequency response and impedance spectroscopy analysis. Considering the uncertain performance of the actuator under varying humidity conditions, an adaptable model using the neural network method is developed. The model uses relative humidity magnitude as one of the model parameters, making it robust to different environmental conditions. Utilizing the model, a closed-loop controller based on the model predictive controller is developed for position control of the actuator. The developed model and controller are experimentally verified and found to be capable of predicting and controlling the actuators with excellent tracking accuracy under relative humidity conditions varying in the range of 10–90%.

Tree-ring stable carbon isotope-based April-June relative humidity reconstruction since ad 1648 in Mt. Tianmu, China

Science.gov (United States)

Liu, Yu; Ta, Weiyuan; Li, Qiang; Song, Huiming; Sun, Changfeng; Cai, Qiufang; Liu, Han; Wang, Lu; Hu, Sile; Sun, Junyan; Zhang, Wenbiao; Li, Wenzhu

2018-03-01

Based on accurate dating, we have determined the stable carbon isotope ratios (δ13C) of five Cryptomeria fortunei specimens from Mt. Tianmu, a subtropical area in southern China. The five δ13C time series records are combined into a single representative δ13C time series using a "numerical mix method." These are normalized to remove temporal variations of δ13 C in atmospheric CO2 to obtain a carbon isotopic discrimination (Δ13C) time series, in which we observe a distinct correlation between Δ13C and local April to June mean relative humidity ( RH AMJ ) (n = 64, r = 0.858, p use this relationship to reconstruct RH AMJ variations from ad 1648 to 2014 at Mt. Tianmu. The reconstructed sequence show that over the past 367 years, Mt. Tianmu area was relatively wet, but in the latter part of the twentieth century, under the influence of increasing global warming, it has experienced a sharp reduction in relative humidity. Spatial correlation analysis reveals a significant negative correlation between RH AMJ at Mt. Tianmu and Sea Surface Temperature (SSTs) in the western equatorial Pacific and Indian Ocean. In other words, there is a positive correlation between tree-ring δ13C in Mt. Tianmu and SSTs. Both observed and reconstructed RH AMJ show significant positive correlations with East Asian and South Asian monsoons from 1951 to 2014, which indicate that RH AMJ from Mt. Tianmu reflects the variability of the Asian summer monsoon intensity to a great extent. The summer monsoon has weakened since 1960. However, an increase in relative humidity since 2003 implies a recent enhancement in the summer monsoon.

Influence of relative humidity in the preservation of irradiated avocados. Part of a coordinated programme on insect disinfestation of food and agricultural products by irradiation

International Nuclear Information System (INIS)

Karmelic, V.J.

1985-02-01

Avocados were irradiated with gamma rays (Cs-137) and subjected to thermal treatment. Relative humidity (RH) is an important factor in this preservation; the higher the RH the longer the shelf-life. PVC was used to maintain the humidity of the fruits

A new approach to very short term wind speed prediction using k-nearest neighbor classification

International Nuclear Information System (INIS)

Yesilbudak, Mehmet; Sagiroglu, Seref; Colak, Ilhami

2013-01-01

Highlights: ► Wind speed parameter was predicted in an n-tupled inputs using k-NN classification. ► The effects of input parameters, nearest neighbors and distance metrics were analyzed. ► Many useful and reasonable inferences were uncovered using the developed model. - Abstract: Wind energy is an inexhaustible energy source and wind power production has been growing rapidly in recent years. However, wind power has a non-schedulable nature due to wind speed variations. Hence, wind speed prediction is an indispensable requirement for power system operators. This paper predicts wind speed parameter in an n-tupled inputs using k-nearest neighbor (k-NN) classification and analyzes the effects of input parameters, nearest neighbors and distance metrics on wind speed prediction. The k-NN classification model was developed using the object oriented programming techniques and includes Manhattan and Minkowski distance metrics except from Euclidean distance metric on the contrary of literature. The k-NN classification model which uses wind direction, air temperature, atmospheric pressure and relative humidity parameters in a 4-tupled space achieved the best wind speed prediction for k = 5 in the Manhattan distance metric. Differently, the k-NN classification model which uses wind direction, air temperature and atmospheric pressure parameters in a 3-tupled inputs gave the worst wind speed prediction for k = 1 in the Minkowski distance metric

Relative humidity effects on water vapour fluxes measured with closed-path eddy-covariance systems with short sampling lines

DEFF Research Database (Denmark)

Fratini, Gerardo; Ibrom, Andreas; Arriga, Nicola

2012-01-01

It has been formerly recognised that increasing relative humidity in the sampling line of closed-path eddy-covariance systems leads to increasing attenuation of water vapour turbulent fluctuations, resulting in strong latent heat flux losses. This occurrence has been analyzed for very long (50 m...... from eddy-covariance systems featuring short (4 m) and very short (1 m) sampling lines running at the same clover field and show that relative humidity effects persist also for these setups, and should not be neglected. Starting from the work of Ibrom and co-workers, we propose a mixed method...... and correction method proposed here is deemed applicable to closed-path systems featuring a broad range of sampling lines, and indeed applicable also to passive gases as a special case. The methods described in this paper are incorporated, as processing options, in the free and open-source eddy...

Effect of relative humidity on onset of capillary forces for rough surfaces.

Science.gov (United States)

Zarate, Nyah V; Harrison, Aaron J; Litster, James D; Beaudoin, Stephen P

2013-12-01

Atomic force microscopy (AFM) was used to investigate the effect of relative humidity (RH) on the adhesion forces between silicon nitride AFM probes, hydrophilic stainless steel, and hydrophobic Perspex® (polymethylmethacrylate, PMMA). In addition, AFM-based phase contrast imaging was used to quantify the amount and location of adsorbed water present on these substrates at RH levels ranging from 15% to 65% at 22°C. Both the adhesion forces and the quantities of adsorbed moisture were seen to vary with RH, and the nature of this variation depended on the hydrophobicity of the substrate. For the Perspex®, both the adhesion force and the amount of adsorbed moisture were essentially independent of RH. For the stainless steel substrate, adsorbed moisture increased continuously with increasing RH, while the adhesion force rose from a minimum at 15% RH to a broad maximum between 25% and 35% RH. From 35% to 55% RH, the adhesion force dropped continuously to an intermediate level before rising again as 65% RH was approached. The changes in adhesion force with increasing relative humidity in the case of the stainless steel substrate were attributed to a balance of effects associated with adsorbed, sub-continuum water on the cantilever and steel. Hydrogen bonding interactions between these adsorbed water molecules were thought to increase the adhesion force. However, when significant quantities of molecular water adsorbed, these molecules were expect to decrease adhesion by screening the van der Waals interactions between the steel and the cantilever tip, and by increasing the separation distance between these solid surfaces when they were 'in contact'. Finally, the slight increase in adhesion between 55% and 65% RH was attributed to true capillary forces exerted by continuum water on the two solid surfaces. Copyright © 2013 Elsevier Inc. All rights reserved.

Integrated monitoring of wind plant systems

Science.gov (United States)

Whelan, Matthew J.; Janoyan, Kerop D.; Qiu, Tong

2008-03-01

Wind power is a renewable source of energy that is quickly gaining acceptance by many. Advanced sensor technologies have currently focused solely on improving wind turbine rotor aerodynamics and increasing of the efficiency of the blade design and concentration. Alternatively, potential improvements in wind plant efficiency may be realized through reduction of reactionary losses of kinetic energy to the structural and substructural systems supporting the turbine mechanics. Investigation of the complete dynamic structural response of the wind plant is proposed using a large-scale, high-rate wireless sensor network. The wireless network enables sensors to be placed across the sizable structure, including the rotating blades, without consideration of cabling issues and the economic burden associated with large spools of measurement cables. A large array of multi-axis accelerometers is utilized to evaluate the modal properties of the system as well as individual members and would enable long-term structural condition monitoring of the wind turbine as well. Additionally, environmental parameters, including wind speed, temperature, and humidity, are wirelessly collected for correlation. Such a wireless system could be integrated with electrical monitoring sensors and actuators and incorporated into a remote multi-turbine centralized plant monitoring and control system.

Vacuum FTIR Observation on the Dynamic Hygroscopicity of Aerosols under Pulsed Relative Humidity.

Science.gov (United States)

Leng, Chun-Bo; Pang, Shu-Feng; Zhang, Yun; Cai, Chen; Liu, Yong; Zhang, Yun-Hong

2015-08-04

A novel approach based on a combination of a pulse RH controlling system and a rapid scan vacuum FTIR spectrometer (PRHCS-RSVFTIR) was utilized to investigate dynamic hygroscopicity of two atmospheric aerosols: ammonium sulfate ((NH4)2SO4) and magnesium sulfate (MgSO4). In this approach, rapid-scan infrared spectra of water vapor and aerosols were obtained to determine relative humidity (RH) in sample cell and hygroscopic property of aerosols with a subsecond time resolution. Heterogeneous nucleation rates of (NH4)2SO4 were, for the first time, measured under low RH conditions (nucleation kinetics of liquid aerosols.

Assurance of MOZAIC/IAGOS relative humidity data quality by evaluating the Capacitive Hygrometer during airborne field studies

Science.gov (United States)

Neis, Patrick; Smit, Herman G. J.; Rohs, Susanne; Rolf, Christian; Krämer, Martina; Ebert, Volker; Buchholz, Bernhard; Bundke, Ulrich; Finger, Fanny; Klingebiel, Marcus; Petzold, Andreas

2015-04-01

Water vapour is a major parameter in weather prediction and climate research but the interaction between the water vapour in the upper troposphere and lowermost stratosphere (UT/LS) and tropopause dynamics are not well understood. A continuous measurement of upper tropospheric humidity (UTH) is difficult because the abundance of UTH is highly variable on spatial and temporal scales that cannot be resolved, neither by the global radiosondes network nor by satellites. Since 1994, data with high spatial and temporal resolution for relative humidity are provided by the in-situ measurements aboard civil passenger aircraft from the MOZAIC/IAGOS-programme (www.iagos.org). The data set emerging from this long-term observation effort builds the backbone of the ongoing in-situ UTH climatology and trend analyses. In order to assess the validity of the long-term water vapour data and its limitations, an analysis of the humidity data sets of two field campaigns is presented. The validation of applied measurement methods, i.e. the MOZAIC/IAGOS Capacitive Hygrometer, is valued on the basis of the aircraft campaigns CIRRUS-III (2006) and AIRTOSS-ICE (2013), where research-grade water vapour instruments were operated simultaneously to the MOZAIC/IAGOS Capacitive Hygrometers. The performance of the MOZAIC Capacitive Hygrometer (MCH; operated from 1994 to 2014 on MOZAIC aircraft) and the advanced IAGOS Capacitive Hygrometer (ICH; operated since 2011 on IAGOS aircraft) are explored in clear sky, in the vicinity of and inside cirrus clouds as a blind intercomparison to the research-grade water vapour instruments. From these intercomparisons the qualification of the Capacitive Hygrometer for the use in long-term observation programmes is successfully demonstrated and the continuation of high data quality is confirmed for the transition from MCH to ICH. In particular the Capacitive Hygrometer response time to changes in relative humidity could be determined for the full range of

Frost Growth and Densification on a Flat Surface in Laminar Flow with Variable Humidity

Science.gov (United States)

Kandula, M.

2012-01-01

Experiments are performed concerning frost growth and densification in laminar flow over a flat surface under conditions of constant and variable humidity. The flat plate test specimen is made of aluminum-6031, and has dimensions of 0.3 mx0.3 mx6.35 mm. Results for the first variable humidity case are obtained for a plate temperature of 255.4 K, air velocity of 1.77 m/s, air temperature of 295.1 K, and a relative humidity continuously ranging from 81 to 54%. The second variable humidity test case corresponds to plate temperature of 255.4 K, air velocity of 2.44 m/s, air temperature of 291.8 K, and a relative humidity ranging from 66 to 59%. Results for the constant humidity case are obtained for a plate temperature of 263.7 K, air velocity of 1.7 m/s, air temperature of 295 K, and a relative humidity of 71.6 %. Comparisons of the data with the author's frost model extended to accommodate variable humidity suggest satisfactory agreement between the theory and the data for both constant and variable humidity.

Relative humidity and activity patterns of Ixodes scapularis (Acari: Ixodidae)

Science.gov (United States)

Berger, K.A.; Ginsberg, Howard S.; Gonzalez, L.; Mather, T.N.

2014-01-01

Laboratory studies have shown clear relationships between relative humidity (RH) and the activity and survival of Ixodes scapularis Say (blacklegged tick). However, field studies have produced conflicting results. We examined this relationship using weekly tick count totals and hourly RH observations at three field sites, stratified by latitude, within the state of Rhode Island. Records of nymphal tick abundance were compared with several RH-related variables (e.g., RH at time of sampling and mean weekly daytime RH). In total, 825 nymphs were sampled in 2009, a year of greater precipitation, with a weighted average leaf litter RH recorded at time of sampling of 85.22%. Alternatively, 649 nymphs were collected in 2010, a year of relatively low precipitation, and a weighted average RH recorded at time of sampling was 75.51%. Negative binomial regression analysis of tick count totals identified cumulative hours <82% RH threshold as a significant factor observed in both years (2009: P = 0.0037; 2010: P < 0.0001). Mean weekly daytime RH did not significantly predict tick activity in either year. However, mean weekly daytime RH recorded with 1-wk lag before sample date was a significant variable (P = 0.0016) in 2010. These results suggest a lag effect between moisture availability and patterns of tick activity and abundance. Differences in the relative importance of each RH variable between years may have been due to abnormally wet summer conditions in 2009.

Modeling the effects of temperature and relative humidity on gas exchange of prickly pear cactus (Opuntia spp.) stems

NARCIS (Netherlands)

Guevara-Arauza, J.C.; Yahia, E.M.; Cedeno, L.; Tijskens, L.M.M.

2006-01-01

A model to estimate gas profile of modified atmosphere packaged (MAP) prickly pear cactus stems was developed and calibrated. The model describes the transient gas exchange taking in consideration the effect of temperature (T) and relative humidity (RH) on film permeability (FPgas), respiration rate

Study of the association of atmospheric temperature and relative humidity with bulk tank milk somatic cell count in dairy herds using Generalized additive mixed models.

Science.gov (United States)

Testa, Francesco; Marano, Giuseppe; Ambrogi, Federico; Boracchi, Patrizia; Casula, Antonio; Biganzoli, Elia; Moroni, Paolo

2017-10-01

Elevated bulk tank milk somatic cell count (BMSCC) has a negative impact on milk production, milk quality, and animal health. Seasonal increases in herd level somatic cell count (SCC) are commonly associated with elevated environmental temperature and humidity. The Temperature Humidity Index (THI) has been developed to measure general environmental stress in dairy cattle; however, additional work is needed to determine a specific effect of the heat stress index on herd-level SCC. Generalized Additive Model methods were used for a flexible exploration of the relationships between daily temperature, relative humidity, and bulk milk somatic cell count. The data consist of BMSCC and meteorological recordings collected between March 2009 and October 2011 of 10 dairy farms. The results indicate that, an average increase of 0.16% of BMSCC is expected for an increase of 1°C degree of temperature. A complex relationship was found for relative humidity. For example, increase of 0.099%, 0.037% and 0.020% are expected in correspondence to an increase of relative humidity from 50% to 51%, 80% to 81%; and 90% to 91%, respectively. Using this model, it will be possible to provide evidence-based advice to dairy farmers for the use of THI control charts created on the basis of our statistical model. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of Relative Humidity and CO2 Concentration on the Properties of Carbonated Reactive MgO Cement Based Materials

Science.gov (United States)

Bilan, Yaroslav

Sustainability of modern concrete industry recently has become an important topic of scientific discussion, and consequently there is an effort to study the potential of the emerging new supplementary cementitious materials. This study has a purpose to investigate the effect of reactive magnesia (reactive MgO) as a replacement for general use (GU) Portland Cements and the effect of environmental factors (CO2 concentrations and relative humidity) on accelerated carbonation curing results. The findings of this study revealed that improvement of physical properties is related directly to the increase in CO2 concentrations and inversely to the increase in relative humidity and also depends much on %MgO in the mixture. The conclusions of this study helped to clarify the effect of variable environmental factors and the material replacement range on carbonation of reactive magnesia concrete materials, as well as providing an assessment of the optimal conditions for the effective usage of the material.

Impact of individually controlled facially applied air movement on perceived air quality at high humidity

DEFF Research Database (Denmark)

Skwarczynski, Mariusz; Melikov, Arsen Krikor; Kaczmarczyk, J.

2010-01-01

and local air velocity under a constant air temperature of 26 degrees C, namely: 70% relative humidity without air movement, 30% relative humidity without air movement and 70% relative humidity with air movement under isothermal conditions. Personalized ventilation was used to supply room air from the front...

Life table parameters of three Mirid Bug (Adelphocoris species (Hemiptera: Miridae under contrasted relative humidity regimes.

Directory of Open Access Journals (Sweden)

Hongsheng Pan

Full Text Available The genus Adelphocoris (Hemiptera: Miridae is a group of important insect pests of Bt cotton in China. The three dominant species are A. lineolatus, A. suturalis, and A. fasciaticollis, and these species have different population dynamics. The causal factors for the differences in population dynamics have not been determined; one hypothesis is that humidity may be important for the growth of Adelphocoris populations. In the laboratory, the demographic parameters of the three Adelphocoris species were compared when the mirid bugs were subjected to various levels of relative humidity (40, 50, 60, 70 and 80% RH. Middle to high levels of RH (60, 70 and 80% were associated with higher egg and nymph survival rates and increased adult longevity and female fecundity. Lower humidity levels (40 and 50% RH had negative effects on the survival of nymphs, adult longevity and fecundity. The intrinsic rate of increase (rm, the net reproductive rate (R0 and the finite rate of increase (λ for each Adelphocoris species increased with increasing RH. Significant positive relationships were found between RH and the life table parameters, rm, R0 and λ for the three Adelphocoris species. These results will help to better understand the phenology of the three Adelphocoris species, and the information can be used in population growth models to optimize pest forecasting and management strategies for these key pests.

circadian rhythm of calling behavior in the emei music frog (babina daunchina)is associated with habitat temperature and relative humidity

Institute of Scientific and Technical Information of China (English)

无

2011-01-01

generally,the function of vocalizations made by male anurans are to attract females or defend resources.typically,males vocalize in choruses during one or more periods in a twenty-four-hour cycle,which varies,however,among species.nevertheless,the causal factors influencing circadian variations of calling patterns in anuran species are not clear.in this study,male chorus vocalizations were monitored in the emei music frog (babina daunchina)for 17 consecutive days during the breeding season,while its habitat air temperature and relative humidity in the course of experiments were measured as well.the results revealed that the circadian calling patterns were characterized by two periods of peak vocalization,which were observed from 0500 h to 0700 h and from 1300 h to 2000 h,while the lowest activity period was found from 2100 h to 2200 h.both calls/h and notes/h were positively correlated with air temperature and negatively with relative humidity.overall,our data indicate that the emei music frogs (b.daunchina)could regulate their vocal activities based on the changes of physical micro-environment (e.g.,temperature or humidity)to maximize reproductive success.

Long-term corrosion/oxidation studies under controlled humidity conditions

International Nuclear Information System (INIS)

Gdowski, G.

1997-01-01

Independent of thermal loading scenarios, the waste packages at the potential repository at Yucca Mountain, Nevada will be exposed to environmental conditions where there is the possibility of significant water film formation occurring on the waste packages. Water films can cause aggressive aqueous film electrochemical corrosion on susceptible metals or alloys. Water film formation will be facilitated when relative humidities are high, when hygroscopic salts are present on the surfaces, when corrosion products are hygroscopic, and when particles form crevices with the surfaces (capillary effect). Also certain gaseous contaminants, such as, NO x and SO 2 , can facilitate water film formation. It should be noted that water film formation can occur at isolated spots (e.g. surface defects and salt particles) and need not cover the entire surface for electrochemical corrosion to occur. This activity will characterize the long term corrosion of metal specimens at two nominal relative humidities (50 and 85%) and at 80 C. Under the low relative humidity (50%) condition, water film formation is expected to be limited and therefore aqueous film electrochemical corrosion is expected also to be limited. Under the high relative humidity (85%) condition, significant water film formation is expected to occur under some test conditions, and subsequently aqueous film electrochemical corrosion will occur on susceptible materials

A complete parameterisation of the relative humidity and wavelength dependence of the refractive index of hygroscopic inorganic aerosol particles

Directory of Open Access Journals (Sweden)

M. I. Cotterell

2017-08-01

Full Text Available Calculations of aerosol radiative forcing require knowledge of wavelength-dependent aerosol optical properties, such as single-scattering albedo. These aerosol optical properties can be calculated using Mie theory from knowledge of the key microphysical properties of particle size and refractive index, assuming that atmospheric particles are well-approximated to be spherical and homogeneous. We provide refractive index determinations for aqueous aerosol particles containing the key atmospherically relevant inorganic solutes of NaCl, NaNO3, (NH42SO4, NH4HSO4 and Na2SO4, reporting the refractive index variation with both wavelength (400–650 nm and relative humidity (from 100 % to the efflorescence value of the salt. The accurate and precise retrieval of refractive index is performed using single-particle cavity ring-down spectroscopy. This approach involves probing a single aerosol particle confined in a Bessel laser beam optical trap through a combination of extinction measurements using cavity ring-down spectroscopy and elastic light-scattering measurements. Further, we assess the accuracy of these refractive index measurements, comparing our data with previously reported data sets from different measurement techniques but at a single wavelength. Finally, we provide a Cauchy dispersion model that parameterises refractive index measurements in terms of both wavelength and relative humidity. Our parameterisations should provide useful information to researchers requiring an accurate and comprehensive treatment of the wavelength and relative humidity dependence of refractive index for the inorganic component of atmospheric aerosol.

Retrofit device and method to improve humidity control of vapor compression cooling systems

Science.gov (United States)

Roth, Robert Paul; Hahn, David C.; Scaringe, Robert P.

2016-08-16

A method and device for improving moisture removal capacity of a vapor compression system is disclosed. The vapor compression system is started up with the evaporator blower initially set to a high speed. A relative humidity in a return air stream is measured with the evaporator blower operating at the high speed. If the measured humidity is above the predetermined high relative humidity value, the evaporator blower speed is reduced from the initially set high speed to the lowest possible speed. The device is a control board connected with the blower and uses a predetermined change in measured relative humidity to control the blower motor speed.

Preparation and Humidity Sensing Properties of KCl/MCM-41 Composite

International Nuclear Information System (INIS)

Li, Liu; Lian-Yuan, Wang; Wei, Li; Li-Ying, Kou; Zhi-Cheng, Zhong; Li-Fang, Liu

2010-01-01

KCl/mobil composition of matter-41 (MCM-41) composite has been synthesized via a heat-treating process and characterized by x-ray diffraction, high resolution transmission electron microscopy, and nitrogen adsorption/desorption isotherms. In contrast with pure MCM-41, KCl/MCM-41 composite exhibits improved humidity sensing properties within the relative humidity range of 11–95%. The impedance of KCl/MCM-41 composite changes by about four orders of magnitude over the whole humidity range with the response time and the recovery times are about 30 s and 35 s, respectively. Small humidity hysteresis and good stability are also observed based on our product. These results make our product a good candidate in fabricating humidity sensors with high performances and low synthetic complexity

A Humidity Sensing Organic-Inorganic Composite for Environmental Monitoring

Directory of Open Access Journals (Sweden)

Khasan S. Karimov

2013-03-01

Full Text Available In this paper, we present the effect of varying humidity levels on the electrical parameters and the multi frequency response of the electrical parameters of an organic-inorganic composite (PEPC+NiPc+Cu2O-based humidity sensor. Silver thin films (thickness ~200 nm were primarily deposited on plasma cleaned glass substrates by the physical vapor deposition (PVD technique. A pair of rectangular silver electrodes was formed by patterning silver film through standard optical lithography technique. An active layer of organic-inorganic composite for humidity sensing was later spun coated to cover the separation between the silver electrodes. The electrical characterization of the sensor was performed as a function of relative humidity levels and frequency of the AC input signal. The sensor showed reversible changes in its capacitance with variations in humidity level. The maximum sensitivity ~31.6 pF/%RH at 100 Hz in capacitive mode of operation has been attained. The aim of this study was to increase the sensitivity of the previously reported humidity sensors using PEPC and NiPc, which has been successfully achieved.

Effect of humidity and temperature on the survival of Listeria monocytogenes on surfaces.

Science.gov (United States)

Redfern, J; Verran, J

2017-04-01

Listeria monocytogenes is a pathogenic bacterium, with human disease and infection linked to dairy products, seafood, ready-to-eat meat and raw & undercooked meats. Stainless steel is the most common food preparation surface and therefore, it is important to understand how food storage conditions such as surface materials, temperature and relative humidity can affect survival of L. monocytogenes. In this study, survival of L. monocytogenes on stainless steel was investigated at three temperatures (4, 10 and 21°C), each approx. 11, 50 and 85% humidity. Results indicate that the lower the temperature, the more cells were recovered in all three humidity environments, while medium humidity enhances survival, irrespective of temperature. Lower humidity decreases recovery at all temperatures. These data support the guidance noted above that humidity control is important, and that lower humidity environments are less likely to support retention of viable L. monocytogenes on a stainless steel surface. Understanding survival of potential food-borne pathogens is essential for the safe production and preparation of food. While it has long been 'common knowledge' that relative humidity can affect the growth and survival of micro-organisms, this study systematically describes the survival of L. monocytogenes on stainless steel under varying humidity and temperatures for the first time. The outcomes from this paper will allow those involved with food manufacture and preparation to make informed judgement on environmental conditions relating to humidity control, which is lacking in the food standards guidelines. © 2017 The Society for Applied Microbiology.

Ethylene sensitivity and relative air humidity regulate root hydraulic properties in tomato plants.

Science.gov (United States)

Calvo-Polanco, Monica; Ibort, Pablo; Molina, Sonia; Ruiz-Lozano, Juan Manuel; Zamarreño, Angel María; García-Mina, Jose María; Aroca, Ricardo

2017-11-01

The effect of ethylene and its precursor ACC on root hydraulic properties, including aquaporin expression and abundance, is modulated by relative air humidity and plant sensitivity to ethylene. Relative air humidity (RH) is a main factor contributing to water balance in plants. Ethylene (ET) is known to be involved in the regulation of root water uptake and stomatal opening although its role on plant water balance under different RH is not very well understood. We studied, at the physiological, hormonal and molecular levels (aquaporins expression, abundance and phosphorylation state), the plant responses to exogenous 1-aminocyclopropane-1-carboxylic acid (ACC; precursor of ET) and 2-aminoisobutyric acid (AIB; inhibitor of ET biosynthesis), after 24 h of application to the roots of tomato wild type (WT) plants and its ET-insensitive never ripe (nr) mutant, at two RH levels: regular (50%) and close to saturation RH. Highest RH induced an increase of root hydraulic conductivity (Lp o ) of non-treated WT plants, and the opposite effect in nr mutants. The treatment with ACC reduced Lp o in WT plants at low RH and in nr plants at high RH. The application of AIB increased Lp o only in nr plants at high RH. In untreated plants, the RH treatment changed the abundance and phosphorylation of aquaporins that affected differently both genotypes according to their ET sensitivity. We show that RH is critical in regulating root hydraulic properties, and that Lp o is affected by the plant sensitivity to ET, and possibly to ACC, by regulating aquaporins expression and their phosphorylation status. These results incorporate the relationship between RH and ET in the response of Lp o to environmental changes.

Impact of individually controlled facially applied air movement on perceived air quality at high humidity

Energy Technology Data Exchange (ETDEWEB)

Skwarczynski, M.A. [Faculty of Environmental Engineering, Institute of Environmental Protection Engineering, Department of Indoor Environment Engineering, Lublin University of Technology, Lublin (Poland); International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Copenhagen (Denmark); Melikov, A.K.; Lyubenova, V. [International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Copenhagen (Denmark); Kaczmarczyk, J. [Faculty of Energy and Environmental Engineering, Department of Heating, Ventilation and Dust Removal Technology, Silesian University of Technology, Gliwice (Poland)

2010-10-15

The effect of facially applied air movement on perceived air quality (PAQ) at high humidity was studied. Thirty subjects (21 males and 9 females) participated in three, 3-h experiments performed in a climate chamber. The experimental conditions covered three combinations of relative humidity and local air velocity under a constant air temperature of 26 C, namely: 70% relative humidity without air movement, 30% relative humidity without air movement and 70% relative humidity with air movement under isothermal conditions. Personalized ventilation was used to supply room air from the front toward the upper part of the body (upper chest, head). The subjects could control the flow rate (velocity) of the supplied air in the vicinity of their bodies. The results indicate an airflow with elevated velocity applied to the face significantly improves the acceptability of the air quality at the room air temperature of 26 C and relative humidity of 70%. (author)

The effect of humidity on the detection of radon

International Nuclear Information System (INIS)

Money, M.; Heaton, B.

1976-01-01

As part of the investigation into the performance of a radon monitoring system the effect of altering the humidity on the levels of radon detected by the system whilst attempting to keep other factors constant, has been investigated. The variations in the levels of radon detected in four experiments, as the humidity of the surrounding atmosphere was artificially raised, are shown graphically together with the variations in temperature and water vapour pressure, as calculated from the relative humidity and saturation vapour pressure. In each case a general rise and fall in radon detected follows a similar rise and fall in humidity, but temperature rise has only a small effect on the radon emanation rate. As the levels of humidity do not alter the rate of emanation it is assumed that the efficiency of collection is altered in some way. Mechanisms are discussed. (U.K.)

Influences of thickness, scanning velocity and relative humidity on the frictional properties of WS2 nanosheets

Science.gov (United States)

Feng, Dongdong; Peng, Jinfeng; Liu, Sisi; Zheng, Xuejun; Yan, Xinyang; He, Wenyuan

2018-01-01

Distinguishing with the traditional cantilever mechanics method, we propose the extended cantilever mechanics method to calibrate the lateral calibration factor by using the normal spring constant obtained from atomic force microscopy (AFM) but not the Young’s modulus and the width of the cantilever, before the influences of thickness, scanning velocity and humidity on the frictional properties are investigated via friction measurement performed by the lateral force mode (LFM) of AFM. Tungsten disulfide (WS2) nanosheets were prepared through hydrothermal intercalation and exfoliation route, and AFM and Raman microscope were used to investigate the frictional properties, thickness and crystalline structure. The friction force and coefficient decrease monotonically with the increase of the nanosheet’s thickness, and the friction coefficient minimum value is close to 0.012 when the thickness larger than 5 nm. The friction property variation on the nanosheet’s thickness can be explained by the puckering effect of tip-sheet adhesion according thickness dependence of bending stiffness in the frame of continuum mechanics. The friction force is a constant value 1.7 nN when the scanning speed larger than the critical value 3.10 μm s-1, while it logarithmically increases for the scanning speed less than the critical value. It is easy to understand through the energy dissipation model and the thermally activated effect. The friction force and friction coefficient increase with the relative humidity at the range of 30%-60%, and the latter is at the range of 0.010-0.013. Influence of relative humidity is discussed via the increasing area of the water monolayer during the water adsorption process. The research can not only enrich nanotribology theory, but also prompt two dimensions materials for nanomechanical applications.

Effects of humidity and surfaces on the melt crystallization of ibuprofen.

Science.gov (United States)

Lee, Dong-Joo; Lee, Suyang; Kim, Il Won

2012-01-01

Melt crystallization of ibuprofen was studied to understand the effects of humidity and surfaces. The molecular self-assembly during the amorphous-to-crystal transformation was examined in terms of the nucleation and growth of the crystals. The crystallization was on Al, Au, and self-assembled monolayers with -CH(3), -OH, and -COOH functional groups. Effects of the humidity were studied at room temperature (18-20 °C) with relative humidity 33%, 75%, and 100%. Effects of the surfaces were observed at -20 °C (relative humidity 36%) to enable close monitoring with slower crystal growth. The nucleation time of ibuprofen was faster at high humidity conditions probably due to the local formation of the unfavorable ibuprofen melt/water interface. The crystal morphologies of ibuprofen were governed by the nature of the surfaces, and they could be associated with the growth kinetics by the Avrami equation. The current study demonstrated the effective control of the melt crystallization of ibuprofen through the melt/atmosphere and melt/surface interfaces.

Studies on the effect of the relative humidity of the atmosphere on the growth and physiology of rice [Oryza sativa] plants, 10: Effect of ambient humidity on the translocation of assimilated 13C in leaves

International Nuclear Information System (INIS)

Hirai, G.; Okumura, T.; Takeuchi, S.; Tanaka, O.; Chujo, H.; Tanaka, N.

1996-01-01

13C-labeled CO2 was fed to rice seedlings for 60 min in the light under low (60%) or high (90%) humidity. The amount of 13C assimilated by the leaves under high humidity was much greater than that by the plants under low humidity. The 13C-labeled CO2 was fed to the plants for 60 min at 75% humidity and then the plants were kept at 60 or 90% humidity under illumination. In 10 hours after the end of 13C feeding, the amount of 13C and 13C content increased in the roots of the plants kept under high humidity. On the other hand, they increased in the sixth leaf and the transfer of 13C to the roots was very low in the plants kept under low humidity. These results support our previous observations that dry matter production of the plants grown under high humidity was higher than that of the plants grown under low humidity, that the dry matter increase of roots in the plants grown under high humidity was higher than that of the plants grown under low humidity and that the stress caused by low humidity increased the partition of dry matter to the top of plants

Power spectral density analysis of wind-shear turbulence for related flight simulations. M.S. Thesis

Science.gov (United States)

Laituri, Tony R.

1988-01-01

Meteorological phenomena known as microbursts can produce abrupt changes in wind direction and/or speed over a very short distance in the atmosphere. These changes in flow characteristics have been labelled wind shear. Because of its adverse effects on aerodynamic lift, wind shear poses its most immediate threat to flight operations at low altitudes. The number of recent commercial aircraft accidents attributed to wind shear has necessitated a better understanding of how energy is transferred to an aircraft from wind-shear turbulence. Isotropic turbulence here serves as the basis of comparison for the anisotropic turbulence which exists in the low-altitude wind shear. The related question of how isotropic turbulence scales in a wind shear is addressed from the perspective of power spectral density (psd). The role of the psd in related Monte Carlo simulations is also considered.

Humidity data for 9975 shipping packages with cane fiberboard

Energy Technology Data Exchange (ETDEWEB)

Daugherty, W. L. [Savannah River Site (SRS), Aiken, SC (United States)

2016-05-01

The 9975 surveillance program is developing a technical basis to support extending the storage period of 9975 packages in K-Area Complex beyond the currently approved 15 years. A key element of this effort is developing a better understanding of degradation of the fiberboard assembly under storage conditions. This degradation is influenced greatly by the moisture content of the fiberboard, which is not well characterized on an individual package basis. Direct measurements of humidity and fiberboard moisture content have been made on two test packages with cane fiberboard and varying internal heat levels from 0 up to 19W. With an internal heat load, a temperature gradient in the fiberboard assembly leads to varying relative humidity in the air around the fiberboard. However, the absolute humidity tends to remain approximately constant throughout the package. The moisture content of fiberboard varies under the influence of several phenomena. Changes in local fiberboard temperature (from an internal heat load) can cause fiberboard moisture changes through absorption or evaporation. Fiberboard degradation at elevated temperature will produce water as a byproduct. And the moisture level within the package is constantly seeking equilibrium with that of the surrounding room air, which varies on a daily and seasonal basis. One indicator of the moisture condition within a 9975 package might be obtained by measuring the relative humidity in the upper air space, by inserting a humidity probe through a caplug hole. However, the data indicate that for the higher internal heat loads (15 and 19 watts), a large variation in internal moisture conditions produces little or no variation in the air space relative humidity. Therefore, this approach does not appear to be sensitive to fiberboard moisture variations at the higher heat loads which are of most interest to maintaining fiberboard integrity.

The effect of environmental humidity and temperature on skin barrier function and dermatitis

DEFF Research Database (Denmark)

Engebretsen, K A; Johansen, J D; Kezic, S

2016-01-01

existing dermatoses. We searched the literature for studies that evaluated the mechanisms behind this phenomenon. Commonly used meteorological terms such as absolute humidity, relative humidity and dew point are explained. Furthermore, we review the negative effect of low humidity, low temperatures...

A simulation-based Data Envelopment Analysis (DEA model to evaluate wind plants locations

Directory of Open Access Journals (Sweden)

Hossein Sameie

2015-04-01

Full Text Available As the world is getting overpopulated and over polluted the human being is seeking to utilize new sources of energy that are cleaner, cheaper, and more accessible. Wind is one of these clean energy sources that is accessible everywhere on the planet earth. This source of energy cannot be stored for later use; therefore, environmental circumstances and geographical location of wind plants are crucial matters. This study proposes a model to decide on the optimum location for a wind farm among the demand area. To tackle the uncertainty related to the geographical position of the nominated location such as wind speed; altitude; mean temperature; and humidity; a simulation method is applied on the problem. Other factors such as the time that a plant is out of service and demand fluctuations also have been considered in the simulation phase. Moreover, a probability distribution function is calculated for the turbine power. Then Data Envelopment Analysis (DEA performs the selection between all the nominated locations for wind farm. The proposed model takes into account several important elements of the problems. Elements such as land cost; average power received from the wind blowing; demand point population etc. are considered at the same time to select the optimum location of wind plants. Finally, the model is applied on a real case in order to demonstrate its reliability and applicability.

Perception of temperature and wind by users of public outdoor spaces: relationships with weather parameters and personal characteristics.

Science.gov (United States)

Andrade, Henrique; Alcoforado, Maria-João; Oliveira, Sandra

2011-09-01

We aim to understand the relationship between people's declared bioclimatic comfort, their personal characteristics (age, origin, clothing, activity and motivation, etc.) and the atmospheric conditions. To attain this goal, questionnaire surveys were made concurrently with weather measurements (air temperature, relative humidity, solar and long-wave radiation and wind speed) in two open leisure areas of Lisbon (Portugal), during the years 2006 and 2007. We analysed the desire expressed by the interviewees to decrease, maintain or increase the values of air temperature and wind speed, in order to improve their level of comfort. Multiple logistic regression was used to analyse the quantitative relation between preference votes and environmental and personal parameters. The preference for a different temperature depends on the season and is strongly associated with wind speed. Furthermore, a general decrease of discomfort with increasing age was also found. Most people declared a preference for lower wind speed in all seasons; the perception of wind shows significant differences depending on gender, with women declaring a lower level of comfort with higher wind speed. It was also found that the tolerance of warmer conditions is higher than of cooler conditions, and that adaptive strategies are undertaken by people to improve their level of comfort outdoors.

The effect of temperature and relative humidity on survival of unfed hyalomma impeltatum (acarina: ixodidae)

OpenAIRE

Hagras, Ahmed E. E. [احمد الوزير هجرس; Babiker, A. A.; Khalil, G. M.

1991-01-01

This work investigates survival of unfed Hyalomma impeltatum in which 8089 larvae, 3946 nymphs, 2058 males and 2304 females held at different combinations of temperature (21, 25, 29 and 34°C) and relative humidity (RH) (32, 52, 75 and 97%) levels. Survival was significantly improved with rise in RH and fall in temperature in all stages. The magnitude of the effect of RH and temperature on survival varied significantly between stages. Changes in RH and temperature had a stronger impact on surv...

The Climatology Module CLIMAT

National Research Council Canada - National Science Library

Avara, Elton

1998-01-01

... (temperature, dew point temperature, absolute humidity, relative humidity, horizontal visibility, sea level pressure, wind speed, wind direction, cloudbase height, cloud cover, and Pasquill stability category...

Objective and Subjective Responses to Low Relative Humidity in an Office Intervention Study

DEFF Research Database (Denmark)

Lagercrantz, Love Per; Wyon, David; Meyer, H. W.

2003-01-01

and objective (clinical) measurements were applied. The following effects of increased humidity were significant, though small: the air was evaluated as less dry (though still on the dry side of neutral), eyes smarted less (by 10% of full scale) eye irritation decreased (by 11%), symptoms of dry throat, mouth......The impact of dry indoor air on comfort and health in winter was investigated in a crossover intervention study in two floors of an office building in northern Sweden. The indoor air humidity (normally 10-20% RH) was raised to 23-24% RH, one floor at a time, using steam humidifiers. Questionnaires...

Regional and site-specific absolute humidity data for use in tritium dose calculations

International Nuclear Information System (INIS)

Etnier, E.L.

1980-01-01

Due to the potential variability in average absolute humidity over the continental U.S., and the dependence of atmospheric 3 H specific activity on absolute humidity, availability of regional absolute humidity data is of value in estimating the radiological significance of 3 H releases. Most climatological data are in the form of relative humidity, which must be converted to absolute humidity for dose calculations. Absolute humidity was calculated for 218 points across the U.S., using the 1977 annual summary of U.S. Climatological Data, and is given in a table. Mean regional values are shown on a map. (author)

Highly Sensitive and Fast Response Colorimetric Humidity Sensors Based on Graphene Oxides Film.

Science.gov (United States)

Chi, Hong; Liu, Yan Jun; Wang, FuKe; He, Chaobin

2015-09-16

Uniform graphene oxide (GO) film for optical humidity sensing was fabricated by dip-coating technique. The resulting GO thin film shows linear optical shifts in the visible range with increase of humidity in the whole relative humidity range (from dry state to 98%). Moreover, GO films exhibit ultrafast sensing to moisture within 250 ms because of the unique atomic thinness and superpermeability of GO sheets. The humidity sensing mechanism was investigated using XRD and computer simulation. The ultrasensitive humidity colorimetric properties of GOs film may enable many potential applications such as disposable humidity sensors for packaging, health, and environmental monitoring.

Room temperature humidity sensor based on polyaniline-tungsten disulfide composite

Science.gov (United States)

Manjunatha, S.; Chethan, B.; Ravikiran, Y. T.; Machappa, T.

2018-05-01

Polyaniline-tungsten disulfide (PANI-WS2) composite was synthesized using in situ polymerization technique by adding finely grinded powder of WS2 during the polymerization of aniline. Field emission scanning electron microscopy (FESEM) images showed the granular morphology with porous nature. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of carbon, nitrogen, chlorine of PANI, tungsten and sulfur elements of WS2. Humidity sensing property of the composite was investigated by plotting change in its resistance with different relative humidity environments ranging from 10 to 97% RH. Decrease in resistance of the composite was observed with increase in relative humidity. Maximum sensing response of the composite was found to be 88.46%. Response and recovery times of the composite at 97%RH were fair enough to fabricate a sensor based on it. Stability of the composite with respect to the humidity sensing behavior was observed to be unchanged even after two months.

Humidity fluctuations in the marine boundary layer measured at a coastal site with an infrared humidity sensor

DEFF Research Database (Denmark)

Sempreviva, A.M.; Gryning, Sven-Erik

1996-01-01

An extensive set of humidity turbulence data has been analyzed from 22-m height in the marine boundary layer. Fluctuations of humidity were measured by an ''OPHIR'', an infrared humidity sensor with a 10 Hz scanning frequency and humidity spectra were produced. The shapes of the normalized spectra...... follow the established similarity functions. However the 10-min time averaged measurements underestimate the value of the absolute humidity. The importance of the humidity flux contribution in a marine environment in calculating the Obukhov stability length has been studied. Deviations from Monin......-Obukhov similarity theory seem to be connected to a low correlation between humidity and temperature....

Wind conditions for wind turbine design

Energy Technology Data Exchange (ETDEWEB)

Maribo Pedersen, B.

1999-04-01

Delegates from Europe and USA attended the meeting and discussed general aspects of wind conditions for wind turbine design. The subjects and the presented papers covered a very broad range of aspects of wind conditions and related influence on the wind turbine. (EHS)

Study on the Correlation between Humidity and Material Strains in Separable Micro Humidity Sensor Design

Directory of Open Access Journals (Sweden)

Chih-Yuan Chang

2017-05-01

Full Text Available Incidents of injuries caused by tiles falling from building exterior walls are frequently reported in Taiwan. Humidity is an influential factor in tile deterioration but it is more difficult to measure the humidity inside a building structure than the humidity in an indoor environment. Therefore, a separable microsensor was developed in this study to measure the humidity of the cement mortar layer with a thickness of 1.5–2 cm inside the external wall of a building. 3D printing technology is used to produce an encapsulation box that can protect the sensor from damage caused by the concrete and cement mortar. The sensor is proven in this study to be capable of measuring temperature and humidity simultaneously and the measurement results are then used to analyze the influence of humidity on external wall tile deterioration.

Wind Farm Wake: The 2016 Horns Rev Photo Case

Directory of Open Access Journals (Sweden)

Charlotte Bay Hasager

2017-03-01

Full Text Available Offshore wind farm wakes were observed and photographed in foggy conditions at Horns Rev 2 on 25 January 2016 at 12:45 UTC. These new images show highly contrasting conditions regarding the wind speed, turbulence intensity, atmospheric stability, weather conditions and wind farm wake development as compared to the Horns Rev 1 photographs from 12 February 2008. The paper examines the atmospheric conditions from satellite images, radiosondes, lidar and wind turbine data and compares the observations to results from atmospheric meso-scale modelling and large eddy simulation. Key findings are that a humid and warm air mass was advected from the southwest over cold sea and the dew-point temperature was such that cold-water advection fog formed in a shallow layer. The flow was stably stratified and the freestream wind speed was 13 m/s at hub height, which means that most turbines produced at or near rated power. The wind direction was southwesterly and long, narrow wakes persisted several rotor diameters downwind of the wind turbines. Eventually mixing of warm air from aloft dispersed the fog in the far wake region of the wind farm.

Effects of Humidity and Surfaces on the Melt Crystallization of Ibuprofen

Directory of Open Access Journals (Sweden)

Il Won Kim

2012-08-01

Full Text Available Melt crystallization of ibuprofen was studied to understand the effects of humidity and surfaces. The molecular self-assembly during the amorphous-to-crystal transformation was examined in terms of the nucleation and growth of the crystals. The crystallization was on Al, Au, and self-assembled monolayers with –CH₃, –OH, and –COOH functional groups. Effects of the humidity were studied at room temperature (18–20 °C with relative humidity 33%, 75%, and 100%. Effects of the surfaces were observed at −20 °C (relative humidity 36% to enable close monitoring with slower crystal growth. The nucleation time of ibuprofen was faster at high humidity conditions probably due to the local formation of the unfavorable ibuprofen melt/water interface. The crystal morphologies of ibuprofen were governed by the nature of the surfaces, and they could be associated with the growth kinetics by the Avrami equation. The current study demonstrated the effective control of the melt crystallization of ibuprofen through the melt/atmosphere and melt/surface interfaces.

System-in Package of Integrated Humidity Sensor Using CMOS-MEMS Technology.

Science.gov (United States)

Lee, Sung Pil

2015-10-01

Temperature/humidity microchips with micropump were fabricated using a CMOS-MEMS process and combined with ZigBee modules to implement a sensor system in package (SIP) for a ubiquitous sensor network (USN) and/or a wireless communication system. The current of a diode temperature sensor to temperature and a normalized current of FET humidity sensor to relative humidity showed linear characteristics, respectively, and the use of the micropump has enabled a faster response. A wireless reception module using the same protocol as that in transmission systems processed the received data within 10 m and showed temperature and humidity values in the display.

Graphene based humidity-insensitive films

KAUST Repository

Tai, Yanlong

2017-09-08

A humidity nonsensitive material based on reduced-graphene oxide (r-GO) and methods of making the same are provided, in an embodiment, the materia! has a resistance/humidity variation of about -15% to 15% based on different sintering time or temperature. In an aspect, the resistance variation to humidity can be close to zero or -0.5% to 0.5%, showing a humidity non sensitivity property. In an embodiment, a humidity nonsensitive material based on the r-GO and carbon nanotube (CNT) composites is provided, wherein the ratio of CNT to r-GO is adjusted. The ratio can be adjusted based on the combined contribution of carbon nanotube (positive resistance variation) and reduced- graphene oxide (negative resistance variation) behaviors.

Effect of temperature and relative humidity on the water vapour permeability and mechanical properties of cassava starch and soy protein concentrate based edible films.

Science.gov (United States)

Chinma, C E; Ariahu, C C; Alakali, J S

2015-04-01

The effect of temperature and relative humidity on the water vapour permeability (WVP) and mechanical properties of cassava starch and soy protein concentrate (SPC) based edible films containing 20 % glycerol level were studied. Tensile strength and elastic modulus of edible films increased with increase in temperature and decreased with increase in relative humidity, while elongation at break decreased. Water vapour permeability of the films increased (2.6-4.3 g.mm/m(2).day.kPa) with increase in temperature and relative humidity. The temperature dependence of water vapour permeation of cassava starch-soy protein concentrate films followed Arrhenius relationship. Activation energy (Ea) of water vapour permeation of cassava starch-soy protein concentrate edible films ranged from 1.9 to 5.3 kJ/mol (R (2)  ≥ 0.93) and increased with increase in SPC addition. The Ea values were lower for the bio-films than for polyvinylidene chloride, polypropylene and polyethylene which are an indication of low water vapour permeability of the developed biofilms compared to those synthetic films.

Influence of Air Humidity and Water Particles on Dust Control Using Ultrasonic Atomization

Science.gov (United States)

Okawa, Hirokazu; Nishi, Kentaro; Shindo, Dai; Kawamura, Youhei

2012-07-01

The influence of air humidity and water particles on dust control was examined using ultrasonic atomization at 2.4 MHz, an acrylic box (61 L), and four types of ore dust samples: green tuff (4 µm), green tuff (6 µm), kaolin, and silica. It was clearly demonstrated that ultrasonic atomization was effective in raising humidity rapidly. However, at high relative air humidity, the water particles remained stable in the box without changing to water vapor. Ultrasonic atomization was applied to suppress dust dispersion and 40-95% dust reduction was achieved at 83% relative air humidity. Dust dispersion was more effective with ultrasonic atomization than without.

Direct versus indirect effects of tropospheric humidity changes on the hydrologic cycle

International Nuclear Information System (INIS)

Sherwood, S C

2010-01-01

Abundant evidence indicates that tropospheric specific humidity increases in a warmer atmosphere, at rates roughly comparable to those at constant relative humidity. While the implications for the planetary energy budget and global warming are well recognized, it is the net atmospheric cooling (or surface heating) that controls the hydrologic cycle. Relative humidity influences this directly through gas-phase radiative transfer, and indirectly by affecting cloud cover (and its radiative effects) and convective heating. Simple calculations show that the two indirect impacts are larger than the direct impact by roughly one and two orders of magnitude respectively. Global or regional relative humidity changes could therefore have significant indirect impacts on energy and water cycles, especially by altering deep convection, even if they are too small to significantly affect global temperature. Studies of climate change should place greater emphasis on these indirect links, which may not be adequately represented in models.

Wind Speed Prediction Using a Univariate ARIMA Model and a Multivariate NARX Model

Directory of Open Access Journals (Sweden)

Erasmo Cadenas

2016-02-01

Full Text Available Two on step ahead wind speed forecasting models were compared. A univariate model was developed using a linear autoregressive integrated moving average (ARIMA. This method’s performance is well studied for a large number of prediction problems. The other is a multivariate model developed using a nonlinear autoregressive exogenous artificial neural network (NARX. This uses the variables: barometric pressure, air temperature, wind direction and solar radiation or relative humidity, as well as delayed wind speed. Both models were developed from two databases from two sites: an hourly average measurements database from La Mata, Oaxaca, Mexico, and a ten minute average measurements database from Metepec, Hidalgo, Mexico. The main objective was to compare the impact of the various meteorological variables on the performance of the multivariate model of wind speed prediction with respect to the high performance univariate linear model. The NARX model gave better results with improvements on the ARIMA model of between 5.5% and 10. 6% for the hourly database and of between 2.3% and 12.8% for the ten minute database for mean absolute error and mean squared error, respectively.

Humidity sensation requires both mechanosensory and thermosensory pathways in Caenorhabditis elegans.

Science.gov (United States)

Russell, Joshua; Vidal-Gadea, Andrés G; Makay, Alex; Lanam, Carolyn; Pierce-Shimomura, Jonathan T

2014-06-03

All terrestrial animals must find a proper level of moisture to ensure their health and survival. The cellular-molecular basis for sensing humidity is unknown in most animals, however. We used the model nematode Caenorhabditis elegans to uncover a mechanism for sensing humidity. We found that whereas C. elegans showed no obvious preference for humidity levels under standard culture conditions, worms displayed a strong preference after pairing starvation with different humidity levels, orienting to gradients as shallow as 0.03% relative humidity per millimeter. Cell-specific ablation and rescue experiments demonstrate that orientation to humidity in C. elegans requires the obligatory combination of distinct mechanosensitive and thermosensitive pathways. The mechanosensitive pathway requires a conserved DEG/ENaC/ASIC mechanoreceptor complex in the FLP neuron pair. Because humidity levels influence the hydration of the worm's cuticle, our results suggest that FLP may convey humidity information by reporting the degree that subcuticular dendritic sensory branches of FLP neurons are stretched by hydration. The thermosensitive pathway requires cGMP-gated channels in the AFD neuron pair. Because humidity levels affect evaporative cooling, AFD may convey humidity information by reporting thermal flux. Thus, humidity sensation arises as a metamodality in C. elegans that requires the integration of parallel mechanosensory and thermosensory pathways. This hygrosensation strategy, first proposed by Thunberg more than 100 y ago, may be conserved because the underlying pathways have cellular and molecular equivalents across a wide range of species, including insects and humans.

Effect of temperature and relative humidity on the development times and survival of Synopsyllus fonquerniei and Xenopsylla cheopis, the flea vectors of plague in Madagascar.

Science.gov (United States)

Kreppel, Katharina S; Telfer, Sandra; Rajerison, Minoarisoa; Morse, Andy; Baylis, Matthew

2016-02-11

Plague, a zoonosis caused by Yersinia pestis, is found in Asia, the Americas but mainly in Africa, with the island of Madagascar reporting almost one third of human cases worldwide. In the highlands of Madagascar, plague is transmitted predominantly by two flea species which coexist on the island, but differ in their distribution. The endemic flea, Synopsyllus fonquerniei, dominates flea communities on rats caught outdoors, while the cosmopolitan flea, Xenopsylla cheopis, is found mostly on rats caught in houses. Additionally S. fonquerniei seems restricted to areas above 800 m. Climatic constraints on the development of the two main vectors of plague could explain the differences in their distribution and the seasonal changes in their abundance. Here we present the first study on effects of temperature and relative humidity on the immature stages of both vector species. We examined the two species' temperature and humidity requirements under experimental conditions at five different temperatures and two relative humidities. By employing multivariate and survival analysis we established the impact of temperature and relative humidity on development times and survival for both species. Using degree-day analysis we then predicted the average developmental threshold for larvae to reach pupation and for pupae to complete development under each treatment. This analysis was undertaken separately for the two relative humidities and for the two species. Development times and time to death differed significantly, with the endemic S. fonquerniei taking on average 1.79 times longer to complete development and having a shorter time to death than X. cheopis under adverse conditions with high temperature and low humidity. Temperature had a significant effect on the development times of flea larvae and pupae. While humidity did not affect the development times of either species, it did influence the time of death of S. fonquerniei. Using degree-day analysis we estimated an

Indoor air humidity, air quality, and health - An overview.

Science.gov (United States)

Wolkoff, Peder

2018-04-01

There is a long-standing dispute about indoor air humidity and perceived indoor air quality (IAQ) and associated health effects. Complaints about sensory irritation in eyes and upper airways are generally among top-two symptoms together with the perception "dry air" in office environments. This calls for an integrated analysis of indoor air humidity and eye and airway health effects. This overview has reviewed the literature about the effects of extended exposure to low humidity on perceived IAQ, sensory irritation symptoms in eyes and airways, work performance, sleep quality, virus survival, and voice disruption. Elevation of the indoor air humidity may positively impact perceived IAQ, eye symptomatology, and possibly work performance in the office environment; however, mice inhalation studies do not show exacerbation of sensory irritation in the airways by low humidity. Elevated humidified indoor air appears to reduce nasal symptoms in patients suffering from obstructive apnea syndrome, while no clear improvement on voice production has been identified, except for those with vocal fatigue. Both low and high RH, and perhaps even better absolute humidity (water vapor), favors transmission and survival of influenza virus in many studies, but the relationship between temperature, humidity, and the virus and aerosol dynamics is complex, which in the end depends on the individual virus type and its physical/chemical properties. Dry and humid air perception continues to be reported in offices and in residential areas, despite the IAQ parameter "dry air" (or "wet/humid air") is semantically misleading, because a sensory organ for humidity is non-existing in humans. This IAQ parameter appears to reflect different perceptions among other odor, dustiness, and possibly exacerbated by desiccation effect of low air humidity. It is salient to distinguish between indoor air humidity (relative or absolute) near the breathing and ocular zone and phenomena caused by moisture

Noise pollution from wind turbine gears loudness of structural noise sources related to gears

International Nuclear Information System (INIS)

Crone, A.

1995-04-01

The purpose of the project has been to develop a method for determination of the structure-borne noise source strength of the gearbox in a typical modern Danish wind turbine construction, with special reference to the tonal noise emission form the turbines. Through study and evaluation of eight potential methods, a simple method has ben formulated. The method is based on measurements of the free vibration velocity level on the gearbox in a load test bed. The relation between this source strength measure and the gearbox related noise from wind turbines has been documented by measurements made during the project together with earlier measurements. The method is intended as a tool for the wind turbine manufacturer, for control of the gearbox related noise from the wind turbines, due to structure-borne noise from the gearbox. It may be used for preparation of specifications to the gearbox manufacturer on test procedure and acceptable source strength levels. Also, it may be used for evaluation of the transmission and radiation of gearbox related noise, for example in order to uncover weaknesses in a prototype turbine. Suggestions for adaptation and evolution of the method has been given, thereby improving the strength of the method for the individual wind turbine manufacturer. (au) 19 refs

MetHumi - Humidity Device for Mars MetNet Lander

Science.gov (United States)

Genzer, Maria; Polkko, Jouni; Harri, Ari-Matti; Schmidt, Walter; Leinonen, Jussi; Mäkinen, Teemu; Haukka, Harri

2010-05-01

MetNet Mars Mission focused for Martian atmospheric science is based on a new semihard landing vehicle called the MetNet Lander (MNL). The MNL will have a versatile science payload focused on the atmospheric science of Mars. The scientific payload of the MetNet Mission encompasses separate instrument packages for the atmospheric entry and descent phase and for the surface operation phase. MetHumi is the humidity sensor of MetNet Lander designed to work on Martian surface. It is based on Humicap® technology developed by Vaisala, Inc. MetHumi is a capacitive type of sensing device where an active polymer film changes capacitance as function of relative humidity. One MetHumi device package consists of one humidity transducer including three Humicap® sensor heads, an accurate temperature sensor head (Thermocap® by Vaisala, Inc.) and constant reference channels. MetHumi is very small, lightweighed and has low power consumption. It weighs only about 15 g without wires, and consumes 15 mW of power. MetHumi can make meaningful relative humidity measurements in range of 0 - 100%RH down to -70°C ambient temperature, but it survives even -135°C ambient temperature.

Characterization of sound emitted by wind machines used for frost control

Energy Technology Data Exchange (ETDEWEB)

Gambino, V.; Gambino, T. [Aercoustics Engineering Ltd., Toronto, ON (Canada); Fraser, H.W. [Ontario Ministry of Agriculture, Food and Rural Affairs, Vineland, ON (Canada)

2007-07-01

Wind machines are used in Niagara-on-the-Lake to protect cold-sensitive crops against cold injury during winter's extreme cold temperatures,spring's late frosts and autumn's early frosts. The number of wind machines in Ontario has about doubled annually from only a few in the late 1990's, to more than 425 in 2006. They are not used for generating power. Noise complaints have multiplied as the number of wind machines has increased. The objective of this study was to characterize the sound produced by wind machines; learn why residents are annoyed by wind machine noise; and suggest ways to possibly reduce sound emissions. One part of the study explored acoustic emission characteristics, the sonic differences of units made by different manufacturers, sound propagation properties under typical use atmospheric conditions and low frequency noise impact potential. Tests were conducted with a calibrated Larson Davis 2900B portable spectrum analyzer. Sound was measured with a microphone whose frequency response covered the range 4 Hz to 20 kHz. The study examined and found several unique acoustic properties that are characteristic of wind machines. It was determined that noise from wind machines is due to both aerodynamic and mechanical effects, but aerodynamic sounds were found to be the most significant. It was concluded that full range or broadband sounds manifest themselves as noise components that extend throughout the audible frequency range from the bladepass frequency to upwards of 1000 Hz. The sound spectrum of a wind machine is full natural tones and impulses that give it a readily identifiable acoustic character. Atmospheric conditions including temperature, lapse rate, relative humidity, mild winds, gradients and atmospheric turbulence all play a significant role in the long range outdoor propagation of sound from wind machines. 6 refs., 6 figs.

On the relation between ionospheric winter anomalies and solar wind

International Nuclear Information System (INIS)

Rumi, G.C.

2001-01-01

There are two different winter anomalies. A small one that appears in connection with ionization at relatively low latitudes in the bottom of the D-region of the ionosphere. There, the electron densities in the winter happen to be less than should be expected. On the other hand, the classic winter anomaly is present when in the winter the upper D-region, again at relatively low latitudes, has more ionization than should be expected. Both these effects are due to the slant compression of the geomagnetic field produced by the solar wind in the wind in the winter season (which is, of course, the summer season when reference is made to events in the other hemisphere). It is shown that the small winter anomaly is a consequence of a hemispheric imbalance in the flux of galactic cosmic rays determined by the obliquely distorted geomagnetic field. It is shown that the standard winter anomaly can be ascribed to the influx of a super solar wind, which penetrates into the Earth's polar atmosphere down to E-region, heights and, duly concentrated through a funneling action at the winter pole of the distorted geomagnetic field, slows down the winter polar vortex. An equatorward motion of the polar air with its content of nitric oxide brings about the excess of ionization in the upper D-region at lower latitudes. The experimentally observed rhythmic recurrence of the upper winter anomaly is correlated to a possible rhythmic recurrence of the super solar wind. The actual detection of the upper winter anomaly could yield some information on the velocity of the basic solar wind. A by-product of the present analysis, the determination of Γ, the coefficient of collisional detachment of the electrons from the O 2 - ions, is presented in the Appendix

On the relation between ionospheric winter anomalies and solar wind

Energy Technology Data Exchange (ETDEWEB)

Rumi, G.C. [Lecco, (Italy)

2001-06-01

There are two different winter anomalies. A small one that appears in connection with ionization at relatively low latitudes in the bottom of the D-region of the ionosphere. There, the electron densities in the winter happen to be less than should be expected. On the other hand, the classic winter anomaly is present when in the winter the upper D-region, again at relatively low latitudes, has more ionization than should be expected. Both these effects are due to the slant compression of the geomagnetic field produced by the solar wind in the wind in the winter season (which is, of course, the summer season when reference is made to events in the other hemisphere). It is shown that the small winter anomaly is a consequence of a hemispheric imbalance in the flux of galactic cosmic rays determined by the obliquely distorted geomagnetic field. It is shown that the standard winter anomaly can be ascribed to the influx of a super solar wind, which penetrates into the Earth's polar atmosphere down to E-region, heights and, duly concentrated through a funneling action at the winter pole of the distorted geomagnetic field, slows down the winter polar vortex. An equatorward motion of the polar air with its content of nitric oxide brings about the excess of ionization in the upper D-region at lower latitudes. The experimentally observed rhythmic recurrence of the upper winter anomaly is correlated to a possible rhythmic recurrence of the super solar wind. The actual detection of the upper winter anomaly could yield some information on the velocity of the basic solar wind. A by-product of the present analysis, the determination of {gamma}, the coefficient of collisional detachment of the electrons from the O{sub 2} {sup -} ions, is presented in the Appendix.

Colorimetric humidity sensor based on liquid composite materials for the monitoring of food and pharmaceuticals.

Science.gov (United States)

Bridgeman, Devon; Corral, Javier; Quach, Ashley; Xian, Xiaojun; Forzani, Erica

2014-09-09

Using supported ionic-liquid membrane (SILM)-inspired methodologies, we have synthesized, characterized, and developed a humidity sensor by coating a liquid composite material onto a hygroscopic, porous substrate. Similar to pH paper, the sensor responds to the environment's relative humidity and changes color accordingly. The humidity indicator is prepared by casting a few microliters of low-toxicity reagents on a nontoxic substrate. The sensing material is a newly synthesized liquid composite that comprises a hygroscopic medium for environmental humidity capture and a color indicator that translates the humidity level into a distinct color change. Sodium borohydride was used to form a liquid composite medium, and DenimBlu30 dye was used as a redox indicator. The liquid composite medium provides a hygroscopic response to the relative humidity, and DenimBlu30 translates the chemical changes into a visual change from yellow to blue. The borate-redox dye-based humidity sensor was prepared, and then Fourier transform infrared spectroscopy, differential scanning calorimetry, and image analysis methods were used to characterize the chemical composition, optimize synthesis, and gain insight into the sensor reactivity. Test results indicated that this new sensing material can detect relative humidity in the range of 5-100% in an irreversible manner with good reproducibility and high accuracy. The sensor is a low-cost, highly sensitive, easy-to-use humidity indicator. More importantly, it can be easily packaged with products to monitor humidity levels in pharmaceutical and food packaging.

Fabrication and Evaluation of a Graphene Oxide-Based Capacitive Humidity Sensor.

Science.gov (United States)

Feng, Jinfeng; Kang, Xiaoxu; Zuo, Qingyun; Yuan, Chao; Wang, Weijun; Zhao, Yuhang; Zhu, Limin; Lu, Hanwei; Chen, Juying

2016-03-01

In this study, a CMOS compatible capacitive humidity sensor structure was designed and fabricated on a 200 mm CMOS BEOL Line. A top Al interconnect layer was used as an electrode with a comb/serpent structure, and graphene oxide (GO) was used as sensing material. XRD analysis was done which shows that GO sensing material has a strong and sharp (002) peak at about 10.278°, whereas graphite has (002) peak at about 26°. Device level CV and IV curves were measured in mini-environments at different relative humidity (RH) level, and saturated salt solutions were used to build these mini-environments. To evaluate the potential value of GO material in humidity sensor applications, a prototype humidity sensor was designed and fabricated by integrating the sensor with a dedicated readout ASIC and display/calibration module. Measurements in different mini-environments show that the GO-based humidity sensor has higher sensitivity, faster recovery time and good linearity performance. Compared with a standard humidity sensor, the measured RH data of our prototype humidity sensor can match well that of the standard product.

Wind Farm Wake: The 2016 Horns Rev Photo Case

DEFF Research Database (Denmark)

Hasager, Charlotte Bay; Nygaard, Nicolai Gayle; Volker, Patrick

2017-01-01

are that a humid and warm air mass was advected from the southwest over cold sea and the dew-point temperature was such that cold-water advection fog formed in a shallow layer. The flow was stably stratified and the freestream wind speed was 13 m/s at hub height, which means that most turbines produced at or near...

Humidity effects on scanning polarization force microscopy imaging

Energy Technology Data Exchange (ETDEWEB)

Shen, Yue, E-mail: shenyue@isl.ac.cn [Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008 (China); Key Laboratory of Interfacial Physics and Technology of Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhou, Yuan, E-mail: zhouy@isl.ac.cn [Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008 (China); Sun, Yanxia; Zhang, Lijuan [Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Ying; Hu, Jun; Zhang, Yi [Key Laboratory of Interfacial Physics and Technology of Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

2017-08-01

Highlights: • The humidity dramatically affects the contrast of scanning polarization force microscopy (SPFM) imaging on mica surface. • This influence roots in the sensitive dielectric constant of mica surface to the humidity change. • A strategy of controllable and repeatable imaging the local dielectric properties of nanomaterials with SPFM is proposed. - Abstract: Scanning polarization force microscopy (SPFM) is a useful surface characterization technique to visually characterize and distinguish nanomaterial with different local dielectric properties at nanometer scale. In this paper, taking the individual one-atom-thick graphene oxide (GO) and reduced graphene oxide (rGO) sheets on mica as examples, we described the influences of environmental humidity on SPFM imaging. We found that the apparent heights (AHs) or contrast of SPFM imaging was influenced significantly by relative humidity (RH) at a response time of a few seconds. And this influence rooted in the sensitive dielectric constant of mica surface to the RH change. While dielectric properties of GO and rGO sheets were almost immune to the humidity change. In addition, we gave the method to determine the critical humidity at which the contrast conversion happened under different conditions. And this is important to the contrast control and repeatable imaging of SPFM through RH adjusting. These findings suggest a strategy of controllable and repeatable imaging the local dielectric properties of nanomaterials with SPFM, which is critically important for further distinguishment, manipulation, electronic applications, etc.

Proceedings of the Canadian Wind Energy Association's 2009 wind matters conference : wind and power systems

International Nuclear Information System (INIS)

2009-01-01

This conference provided a forum for wind energy and electric power industry experts to discuss issues related to wind and power systems. An overview of wind integration studies and activities in Canada and the United States was provided. New tools and technologies for facilitating the integration of wind and improve market conditions for wind energy developers were presented. Methods of increasing wind penetration were evaluated, and technical issues related to wind interconnections throughout North America were reviewed. The conference was divided into the following 5 sessions: (1) experiences with wind integration, and lessons learned, (2) update on ongoing wind integration initiatives in Canada and the United States, (3) initiatives and tools to facilitate wind integration and market access, (4) developments in wind interconnection and grid codes, (5) wind energy and cold weather considerations, and (6) challenges to achieving the 20 per cent WindVision goal in Canada. The conference featured 21 presentations, of which 13 have been catalogued separately for inclusion in this database. refs., tabs., figs

Floral humidity as a reliable sensory cue for profitability assessment by nectar-foraging hawkmoths.

Science.gov (United States)

von Arx, Martin; Goyret, Joaquín; Davidowitz, Goggy; Raguso, Robert A

2012-06-12

Most research on plant-pollinator communication has focused on sensory and behavioral responses to relatively static cues. Floral rewards such as nectar, however, are dynamic, and foraging animals will increase their energetic profit if they can make use of floral cues that more accurately indicate nectar availability. Here we document such a cue--transient humidity gradients--using the night blooming flowers of Oenothera cespitosa (Onagraceae). The headspace of newly opened flowers reaches levels of about 4% above ambient relative humidity due to additive evapotranspirational water loss through petals and water-saturated air from the nectar tube. Floral humidity plumes differ from ambient levels only during the first 30 min after anthesis (before nectar is depleted in wild populations), whereas other floral traits (scent, shape, and color) persist for 12-24 h. Manipulative experiments indicated that floral humidity gradients are mechanistically linked to nectar volume and therefore contain information about energy rewards to floral visitors. Behavioral assays with Hyles lineata (Sphingidae) and artificial flowers with appropriate humidity gradients suggest that these hawkmoth pollinators distinguish between subtle differences in relative humidity when other floral cues are held constant. Moths consistently approached and probed flowers with elevated humidity over those with ambient humidity levels. Because floral humidity gradients are largely produced by the evaporation of nectar itself, they represent condition-informative cues that facilitate remote sensing of floral profitability by discriminating foragers. In a xeric environment, this level of honest communication should be adaptive when plant reproductive success is pollinator limited, due to intense competition for the attention of a specialized pollinator.

Floral humidity as a reliable sensory cue for profitability assessment by nectar-foraging hawkmoths

Science.gov (United States)

von Arx, Martin; Goyret, Joaquín; Davidowitz, Goggy; Raguso, Robert A.

2012-01-01

Most research on plant–pollinator communication has focused on sensory and behavioral responses to relatively static cues. Floral rewards such as nectar, however, are dynamic, and foraging animals will increase their energetic profit if they can make use of floral cues that more accurately indicate nectar availability. Here we document such a cue—transient humidity gradients—using the night blooming flowers of Oenothera cespitosa (Onagraceae). The headspace of newly opened flowers reaches levels of about 4% above ambient relative humidity due to additive evapotranspirational water loss through petals and water-saturated air from the nectar tube. Floral humidity plumes differ from ambient levels only during the first 30 min after anthesis (before nectar is depleted in wild populations), whereas other floral traits (scent, shape, and color) persist for 12–24 h. Manipulative experiments indicated that floral humidity gradients are mechanistically linked to nectar volume and therefore contain information about energy rewards to floral visitors. Behavioral assays with Hyles lineata (Sphingidae) and artificial flowers with appropriate humidity gradients suggest that these hawkmoth pollinators distinguish between subtle differences in relative humidity when other floral cues are held constant. Moths consistently approached and probed flowers with elevated humidity over those with ambient humidity levels. Because floral humidity gradients are largely produced by the evaporation of nectar itself, they represent condition-informative cues that facilitate remote sensing of floral profitability by discriminating foragers. In a xeric environment, this level of honest communication should be adaptive when plant reproductive success is pollinator limited, due to intense competition for the attention of a specialized pollinator. PMID:22645365

Lead Oxide- PbO Humidity Sensor

Directory of Open Access Journals (Sweden)

Sk. Khadeer Pasha

2010-11-01

Full Text Available Alcohol thermal route has been used to synthesize nanocrystalline PbO at a low temperature of 75 oC using lead acetate. The synthesized PbO (P75 was annealed in the temperatures ranging from 200-500 oC for 2 h to study the effect of crystal structure and phase changes and were labeled as P200, P300, P400 and P500, respectively. X-Ray diffraction and FT-IR spectroscopy were carried out to identify the structural phases and vibrational stretching frequencies respectively. The TEM images revealed the porous nature of P75 sample which is an important criterion for the humidity sensor. The dc resistance measurements were carried out in the relative humidity (RH range 5-98 %. Among the different prepared, P75 possessed the highest humidity sensitivity of 6250, while the heat treated sample P500 have a low sensitivity of 330. The response and recovery characteristics of the maximum sensitivity sample P75 were 170 s and 40 s respectively.

Mixing of secondary organic aerosols versus relative humidity

Science.gov (United States)

Ye, Qing; Robinson, Ellis Shipley; Ding, Xiang; Ye, Penglin

2016-01-01

Atmospheric aerosols exert a substantial influence on climate, ecosystems, visibility, and human health. Although secondary organic aerosols (SOA) dominate fine-particle mass, they comprise myriad compounds with uncertain sources, chemistry, and interactions. SOA formation involves absorption of vapors into particles, either because gas-phase chemistry produces low-volatility or semivolatile products that partition into particles or because more-volatile organics enter particles and react to form lower-volatility products. Thus, SOA formation involves both production of low-volatility compounds and their diffusion into particles. Most chemical transport models assume a single well-mixed phase of condensing organics and an instantaneous equilibrium between bulk gas and particle phases; however, direct observations constraining diffusion of semivolatile organics into particles containing SOA are scarce. Here we perform unique mixing experiments between SOA populations including semivolatile constituents using quantitative, single-particle mass spectrometry to probe any mass-transfer limitations in particles containing SOA. We show that, for several hours, particles containing SOA from toluene oxidation resist exchange of semivolatile constituents at low relative humidity (RH) but start to lose that resistance above 20% RH. Above 40% RH, the exchange of material remains constant up to 90% RH. We also show that dry particles containing SOA from α-pinene ozonolysis do not appear to resist exchange of semivolatile compounds. Our interpretation is that in-particle diffusion is not rate-limiting to mass transfer in these systems above 40% RH. To the extent that these systems are representative of ambient SOA, we conclude that diffusion limitations are likely not common under typical ambient boundary layer conditions. PMID:27791066

Mixing of secondary organic aerosols versus relative humidity.

Science.gov (United States)

Ye, Qing; Robinson, Ellis Shipley; Ding, Xiang; Ye, Penglin; Sullivan, Ryan C; Donahue, Neil M

2016-10-24

Atmospheric aerosols exert a substantial influence on climate, ecosystems, visibility, and human health. Although secondary organic aerosols (SOA) dominate fine-particle mass, they comprise myriad compounds with uncertain sources, chemistry, and interactions. SOA formation involves absorption of vapors into particles, either because gas-phase chemistry produces low-volatility or semivolatile products that partition into particles or because more-volatile organics enter particles and react to form lower-volatility products. Thus, SOA formation involves both production of low-volatility compounds and their diffusion into particles. Most chemical transport models assume a single well-mixed phase of condensing organics and an instantaneous equilibrium between bulk gas and particle phases; however, direct observations constraining diffusion of semivolatile organics into particles containing SOA are scarce. Here we perform unique mixing experiments between SOA populations including semivolatile constituents using quantitative, single-particle mass spectrometry to probe any mass-transfer limitations in particles containing SOA. We show that, for several hours, particles containing SOA from toluene oxidation resist exchange of semivolatile constituents at low relative humidity (RH) but start to lose that resistance above 20% RH. Above 40% RH, the exchange of material remains constant up to 90% RH. We also show that dry particles containing SOA from α-pinene ozonolysis do not appear to resist exchange of semivolatile compounds. Our interpretation is that in-particle diffusion is not rate-limiting to mass transfer in these systems above 40% RH. To the extent that these systems are representative of ambient SOA, we conclude that diffusion limitations are likely not common under typical ambient boundary layer conditions.

Absolute humidity and the seasonal onset of influenza in the continental United States.

Directory of Open Access Journals (Sweden)

Jeffrey Shaman

2010-02-01

Full Text Available Much of the observed wintertime increase of mortality in temperate regions is attributed to seasonal influenza. A recent reanalysis of laboratory experiments indicates that absolute humidity strongly modulates the airborne survival and transmission of the influenza virus. Here, we extend these findings to the human population level, showing that the onset of increased wintertime influenza-related mortality in the United States is associated with anomalously low absolute humidity levels during the prior weeks. We then use an epidemiological model, in which observed absolute humidity conditions temper influenza transmission rates, to successfully simulate the seasonal cycle of observed influenza-related mortality. The model results indicate that direct modulation of influenza transmissibility by absolute humidity alone is sufficient to produce this observed seasonality. These findings provide epidemiological support for the hypothesis that absolute humidity drives seasonal variations of influenza transmission in temperate regions.

Stratified magnetically driven accretion-disk winds and their relations to jets

International Nuclear Information System (INIS)

Fukumura, Keigo; Tombesi, Francesco; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Contopoulos, Ioannis

2014-01-01

We explore the poloidal structure of two-dimensional magnetohydrodynamic (MHD) winds in relation to their potential association with the X-ray warm absorbers (WAs) and the highly ionized ultra-fast outflows (UFOs) in active galactic nuclei (AGNs), in a single unifying approach. We present the density n(r, θ), ionization parameter ξ(r, θ), and velocity structure v(r, θ) of such ionized winds for typical values of their fluid-to-magnetic flux ratio, F, and specific angular momentum, H, for which wind solutions become super-Alfvénic. We explore the geometrical shape of winds for different values of these parameters and delineate the values that produce the widest and narrowest opening angles of these winds, quantities necessary in the determination of the statistics of AGN obscuration. We find that winds with smaller H show a poloidal geometry of narrower opening angles with their Alfvén surface at lower inclination angles and therefore they produce the highest line of sight (LoS) velocities for observers at higher latitudes with the respect to the disk plane. We further note a physical and spatial correlation between the X-ray WAs and UFOs that form along the same LoS to the observer but at different radii, r, and distinct values of n, ξ, and v consistent with the latest spectroscopic data of radio-quiet Seyfert galaxies. We also show that, at least in the case of 3C 111, the winds' pressure is sufficient to contain the relativistic plasma responsible for its radio emission. Stratified MHD disk winds could therefore serve as a unique means to understand and unify the diverse AGN outflows.

New calculation method for thermodynamic properties of humid air in humid air turbine cycle – The general model and solutions for saturated humid air

International Nuclear Information System (INIS)

Wang, Zidong; Chen, Hanping; Weng, Shilie

2013-01-01

The article proposes a new calculation method for thermodynamic properties (i.e. specific enthalpy, specific entropy and specific volume) of humid air in humid air turbine cycle. The research pressure range is from 0.1 MPa to 5 MPa. The fundamental behaviors of dry air and water vapor in saturated humid air are explored in depth. The new model proposes and verifies the relationship between total gas mixture pressure and gas component pressures. This provides a good explanation of the fundamental behaviors of gas components in gas mixture from a new perspective. Another discovery is that the water vapor component pressure of saturated humid air equals P S , always smaller than its partial pressure (f·P S ) which was believed in the past researches. In the new model, “Local Gas Constant” describes the interaction between similar molecules. “Improvement Factor” is proposed for the first time by this article, and it quantitatively describes the magnitude of interaction between dissimilar molecules. They are combined to fully describe the real thermodynamic properties of humid air. The average error of Revised Dalton's Method is within 0.1% compared to experimentally-based data. - Highlights: • Our new model is suitable to calculate thermodynamic properties of humid air in HAT cycle. • Fundamental behaviors of dry air and water vapor in saturated humid air are explored in depth. • Local-Gas-Constant describes existing alone component and Improvement Factor describes interaction between different components. • The new model proposes and verifies the relationship between total gas mixture pressure and component pressures. • It solves saturated humid air thoroughly and deviates from experimental data less than 0.1%

Effects of Humidity and Surfaces on the Melt Crystallization of Ibuprofen

OpenAIRE

Lee, Dong-Joo; Lee, Suyang; Kim, Il Won

2012-01-01

Melt crystallization of ibuprofen was studied to understand the effects of humidity and surfaces. The molecular self-assembly during the amorphous-to-crystal transformation was examined in terms of the nucleation and growth of the crystals. The crystallization was on Al, Au, and self-assembled monolayers with –CH₃, –OH, and –COOH functional groups. Effects of the humidity were studied at room temperature (18–20 °C) with relative humidity 33%, 75%, and 100%. Effects of t...

Angle-tip Fiber Probe as Humidity Sensor

Directory of Open Access Journals (Sweden)

Pabitra NATH

2010-05-01

Full Text Available In this paper, I present a simple fiber optic relative humidity sensor (FORHS using an angled-tip multimode optical fiber. The sensing region is fabricated by coating moisture sensitive Cobalt Chloride (CoCl2 doped polyvinyl alcohol (PVA film on the surface of fiber optic tip. Light signal introducing from flat-end of the fiber is back-reflected at the fiber tip-air interface by the effect of total internal refection. The change of relative humidity (RH in the outstanding medium affects of evanescent field absorption at the fiber tip-sensing film interface thus, modulates the back-reflected signal. With the present sensing investigation, RH ranging from 5 % to 95 % can be measured with high degree of repeatability and has a fast response time of about 2 seconds.

Habitat use of bats in relation to wind turbines revealed by GPS tracking

Science.gov (United States)

Roeleke, Manuel; Blohm, Torsten; Kramer-Schadt, Stephanie; Yovel, Yossi; Voigt, Christian C.

2016-07-01

Worldwide, many countries aim at countering global climate change by promoting renewable energy. Yet, recent studies highlight that so-called green energy, such as wind energy, may come at environmental costs, for example when wind turbines kill birds and bats. Using miniaturized GPS loggers, we studied how an open-space foraging bat with high collision risk with wind turbines, the common noctule Nyctalus noctula (Schreber, 1774), interacts with wind turbines. We compared actual flight trajectories to correlated random walks to identify habitat variables explaining the movements of bats. Both sexes preferred wetlands but used conventionally managed cropland less than expected based on availability. During midsummer, females traversed the land on relatively long flight paths and repeatedly came close to wind turbines. Their flight heights above ground suggested a high risk of colliding with wind turbines. In contrast, males recorded in early summer commuted straight between roosts and foraging areas and overall flew lower than the operating range of most turbine blades, suggesting a lower collision risk. Flight heights of bats suggest that during summer the risk of collision with wind turbines was high for most studied bats at the majority of currently installed wind turbines. For siting of wind parks, preferred bat habitats and commuting routes should be identified and avoided.

Can thermal perception in a building be predicted by the perceived spatial openness of a building in a hot and humid climate?

NARCIS (Netherlands)

Du, X.; Bokel, R.M.J.; van den Dobbelsteen, A.A.J.F.; Brotas, Luisa; Roaf, Susan; Nicol, Fergus

2017-01-01

The authors wanted to prove that there is a large correlation between the concepts spatial openness and comfort (visual, wind speed and thermal) perception in people’s minds in a hot and humid climate in summer in order to be able to use spatial configuration parameters such as openness,

Controlling indoor climate. Passive cooling of residential buildings in hot-humid climates in China

Energy Technology Data Exchange (ETDEWEB)

Zhiwu, Wang

1996-10-01

Overheating is a paramount problem in residential buildings in hot and humid climates in China during summer. This study aims to deal with the overheating problem and the problem of poor air quality in dwellings. The main objective is to improve indoor thermal conditions by passive cooling approaches, climatisation techniques in buildings without auxiliary cooling from air conditioning equipment. This thesis focuses on the study of cross-ventilation in apartments, which is one of the most effective ways of natural cooling in a hot humid climate, but is also one of the least understood parts in controlling indoor climate. The Computational Fluid Dynamics (CFD) technique is used, which is a new approach, since cross-ventilation studies have been conventionally made by wind tunnel tests. The validations of the CFD technique are examined by a comparison between wind tunnel tests and computer simulations. The factors influencing indoor air movement are investigated for a single room. Cross-ventilation in two apartments is studied, and the air change efficiency in a Chinese kitchen is calculated with CFD techniques. The thermal performance of ventilated roofs, a simple and widely used type of roof in the region, is specially addressed by means of a full-scale measurement, wind tunnel tests and computer simulations. An integrated study of passive cooling approaches and factors affecting indoor thermal comfort is carried out through a case study in a southern Chinese city, Guangzhou. This thesis demonstrates that passive cooling measure have a high potential in significantly improving indoor thermal conditions during summer. This study also gives discussions and conclusions on the evaluation of indoor thermal environment; effects influencing cross-ventilation in apartments; design guidelines for ventilated roofs and an integrated study of passive cooling. 111 refs, 83 figs, 65 tabs

Fabrication of Porous Silicon Based Humidity Sensing Elements on Paper

Directory of Open Access Journals (Sweden)

Tero Jalkanen

2015-01-01

Full Text Available A roll-to-roll compatible fabrication process of porous silicon (pSi based sensing elements for a real-time humidity monitoring is described. The sensing elements, consisting of printed interdigitated silver electrodes and a spray-coated pSi layer, were fabricated on a coated paper substrate by a two-step process. Capacitive and resistive responses of the sensing elements were examined under different concentrations of humidity. More than a three orders of magnitude reproducible decrease in resistance was measured when the relative humidity (RH was increased from 0% to 90%. A relatively fast recovery without the need of any refreshing methods was observed with a change in RH. Humidity background signal and hysteresis arising from the paper substrate were dependent on the thickness of sensing pSi layer. Hysteresis in most optimal sensing element setup (a thick pSi layer was still noticeable but not detrimental for the sensing. In addition to electrical characterization of sensing elements, thermal degradation and moisture adsorption properties of the paper substrate were examined in connection to the fabrication process of the silver electrodes and the moisture sensitivity of the paper. The results pave the way towards the development of low-cost humidity sensors which could be utilized, for example, in smart packaging applications or in smart cities to monitor the environment.

Evaluation of wind farm efficiency and wind turbine wakes at the Nysted offshore wind farm

DEFF Research Database (Denmark)

Barthelmie, Rebecca Jane; Jensen, L.E.

2010-01-01

Here, we quantify relationships between wind farm efficiency and wind speed, direction, turbulence and atmospheric stability using power output from the large offshore wind farm at Nysted in Denmark. Wake losses are, as expected, most strongly related to wind speed variations through the turbine...... thrust coefficient; with direction, atmospheric stability and turbulence as important second order effects. While the wind farm efficiency is highly dependent on the distribution of wind speeds and wind direction, it is shown that the impact of turbine spacing on wake losses and turbine efficiency can...... be quantified, albeit with relatively large uncertainty due to stochastic effects in the data. There is evidence of the ‘deep array effect’ in that wake losses in the centre of the wind farm are under-estimated by the wind farm model WAsP, although overall efficiency of the wind farm is well predicted due...

Humidity dependence of adhesion for silane coated microcantilevers

International Nuclear Information System (INIS)

De Boer, Maarten P.; Mayer, Thomas M.; Carpick, Robert W.; Michalske, Terry A.; Srinivasan, U.; Maboudian, R.

1999-01-01

This study examines adhesion between silane-coated micromachined surfaces that are exposed to humid conditions. Our quantitative values for interfacial adhesion energies are determined from an in-situ optical measurement of deformations in partly-adhered cantilever beams. We coated micromachined cantilevers with either ODTS (C(sub 18)H(sub 37)SiCl(sub 3)) or FDTS (C(sub 8)F(sub 17)C(sub 2)H(sub 4)SiCl(sub 3)) with the objective of creating hydrophobic surfaces whose adhesion would be independent of humidity. In both cases, the adhesion energy is significantly lower than for uncoated, hydrophilic surfaces. For relative humidities (RH) less than 95% (ODTS) and 80% (FDTS) the adhesion energy was extremely low and constant. In fact, ODTS-coated beams exposed to saturated humidity conditions and long (48 hour) exposures showed only a factor of two increase in adhesion energy. Surprisingly, FDTS coated beams, which initially have a higher contact angle (115(degree)) with water than do ODTS coated beams (112(degree)), proved to be much more sensitive to humidity. The FDTS coated surfaces showed a factor of one hundred increase in adhesion energy after a seven hour exposure to 90% RH. Atomic force microscopy revealed agglomerated coating material after exposed to high RH, suggesting a redistribution of the monolayer film. This agglomeration was more prominent for FDTS than ODTS. These findings suggest a new mechanism for uptake of moisture under high humidity conditions. At high humidities, the silane coatings can reconfigure from a surface to a bulk phase leaving behind locally hydrophilic sites which increase the average measured adhesion energy. In order for the adhesion increase to be observed, a significant fraction of the monolayer must be converted from the surface to the bulk phase

Fabrication and Evaluation of a Graphene Oxide-Based Capacitive Humidity Sensor

Directory of Open Access Journals (Sweden)

Jinfeng Feng

2016-03-01

Full Text Available In this study, a CMOS compatible capacitive humidity sensor structure was designed and fabricated on a 200 mm CMOS BEOL Line. A top Al interconnect layer was used as an electrode with a comb/serpent structure, and graphene oxide (GO was used as sensing material. XRD analysis was done which shows that GO sensing material has a strong and sharp (002 peak at about 10.278°, whereas graphite has (002 peak at about 26°. Device level CV and IV curves were measured in mini-environments at different relative humidity (RH level, and saturated salt solutions were used to build these mini-environments. To evaluate the potential value of GO material in humidity sensor applications, a prototype humidity sensor was designed and fabricated by integrating the sensor with a dedicated readout ASIC and display/calibration module. Measurements in different mini-environments show that the GO-based humidity sensor has higher sensitivity, faster recovery time and good linearity performance. Compared with a standard humidity sensor, the measured RH data of our prototype humidity sensor can match well that of the standard product.

Artificial Fruit: Postharvest Online Monitoring of Agricultural Food by Measuring Humidity and Temperature

Science.gov (United States)

Hübert, T.; Lang, C.

2012-09-01

An online monitoring of environmental and inherent product parameters is required during transportation and storage of fruit and vegetables to avoid quality degradation and spoilage. The control of transpiration losses is suggested as an indicator for fruit freshness by humidity measurements. For that purpose, an electronic sensor is surrounded by a wet porous fiber material which is in contact with the outer atmosphere. Transpiration reduces the water content of the porous material and thus also the internal water activity. The sensor system, known as "artificial fruit," measures the relative humidity and temperature inside the wet material. Humidity and temperature data are collected and transmitted on demand by a miniaturized radio communication unit. The decrease in the measured relative humidity has been calibrated against the mass loss of tomatoes under different external influencing parameters such as temperature, humidity, and air flow. Current battery life allows the sensor system, embedded in a fruit crate, to transmit data on transpiration losses via radio transmission for up to two weeks.

Influence of relative humidity and physical load during storage on dustiness of inorganic nanomaterials: implications for testing and risk assessment

Energy Technology Data Exchange (ETDEWEB)

Levin, Marcus, E-mail: mle@nrcwe.dk [Technical University of Denmark, Department of Micro and Nanotechnology (Denmark); Rojas, Elena [CIC biomaGUNE (Spain); Vanhala, Esa; Vippola, Minnamari [Finnish Institute of Occupational Health (Finland); Liguori, Biase; Kling, Kirsten I.; Koponen, Ismo K. [National Research Centre for the Working Environment (Denmark); Mølhave, Kristian [Technical University of Denmark, Department of Micro and Nanotechnology (Denmark); Tuomi, Timo [Finnish Institute of Occupational Health (Finland); Gregurec, Danijela; Moya, Sergio [CIC biomaGUNE (Spain); Jensen, Keld A. [National Research Centre for the Working Environment (Denmark)

2015-08-15

Dustiness testing using a down-scaled EN15051 rotating drum was used to investigate the effects of storage conditions such as relative humidity and physical loading on the dustiness of five inorganic metal oxide nanostructured powder materials. The tests consisted of measurements of gravimetrical respirable dustiness index and particle size distributions. Water uptake of the powders during 7 days of incubation was investigated as an explanatory factor of the changes. Consequences of these varying storage conditions in exposure modelling were tested using the control banding and risk management tool NanoSafer. Drastic material-specific effects on powder respirable dustiness index were observed with the change in TiO{sub 2} from 30 % RH (639 mg/kg) to 50 % RH (1.5 mg/kg). All five tested materials indicate a decreasing dustiness index with relative humidity increasing from 30 to 70 % RH. Test of powder water uptake showed an apparent link with the decreasing dustiness index. Effects of powder compaction appeared more material specific with both increasing and decreasing dustiness indices observed as an effect of compaction. Tests of control banding exposure models using the measured dustiness indices in three different exposure scenarios showed that in two of the tested materials, one 20 % change in RH changed the exposure banding from the lowest level to the highest. The study shows the importance of powder storage conditions prior to tests for classification of material dustiness indices. It also highlights the importance of correct storage information and relative humidity and expansion of the dustiness test conditions specifically, when using dustiness indices as a primary parameter for source strength in exposure assessment.

Influence of relative humidity and physical load during storage on dustiness of inorganic nanomaterials: implications for testing and risk assessment

International Nuclear Information System (INIS)

Levin, Marcus; Rojas, Elena; Vanhala, Esa; Vippola, Minnamari; Liguori, Biase; Kling, Kirsten I.; Koponen, Ismo K.; Mølhave, Kristian; Tuomi, Timo; Gregurec, Danijela; Moya, Sergio; Jensen, Keld A.

2015-01-01

Dustiness testing using a down-scaled EN15051 rotating drum was used to investigate the effects of storage conditions such as relative humidity and physical loading on the dustiness of five inorganic metal oxide nanostructured powder materials. The tests consisted of measurements of gravimetrical respirable dustiness index and particle size distributions. Water uptake of the powders during 7 days of incubation was investigated as an explanatory factor of the changes. Consequences of these varying storage conditions in exposure modelling were tested using the control banding and risk management tool NanoSafer. Drastic material-specific effects on powder respirable dustiness index were observed with the change in TiO 2 from 30 % RH (639 mg/kg) to 50 % RH (1.5 mg/kg). All five tested materials indicate a decreasing dustiness index with relative humidity increasing from 30 to 70 % RH. Test of powder water uptake showed an apparent link with the decreasing dustiness index. Effects of powder compaction appeared more material specific with both increasing and decreasing dustiness indices observed as an effect of compaction. Tests of control banding exposure models using the measured dustiness indices in three different exposure scenarios showed that in two of the tested materials, one 20 % change in RH changed the exposure banding from the lowest level to the highest. The study shows the importance of powder storage conditions prior to tests for classification of material dustiness indices. It also highlights the importance of correct storage information and relative humidity and expansion of the dustiness test conditions specifically, when using dustiness indices as a primary parameter for source strength in exposure assessment

Opposing effects of humidity on rhodochrosite surface oxidation.

Science.gov (United States)

Na, Chongzheng; Tang, Yuanzhi; Wang, Haitao; Martin, Scot T

2015-03-03

Rhodochrosite (MnCO3) is a model mineral representing carbonate aerosol particles containing redox-active elements that can influence particle surface reconstruction in humid air, thereby affecting the heterogeneous transformation of important atmospheric constituents such as nitric oxides, sulfur dioxides, and organic acids. Using in situ atomic force microscopy, we show that the surface reconstruction of rhodochrosite in humid oxygen leads to the formation and growth of oxide nanostructures. The oxidative reconstruction consists of two consecutive processes with distinctive time scales, including a long waiting period corresponding to slow nucleation and a rapid expansion phase corresponding to fast growth. By varying the relative humidity from 55 to 78%, we further show that increasing humidity has opposing effects on the two processes, accelerating nucleation from 2.8(±0.2) × 10(-3) to 3.0(±0.2) × 10(-2) h(-1) but decelerating growth from 7.5(±0.3) × 10(-3) to 3.1(±0.1) × 10(-3) μm(2) h(-1). Through quantitative analysis, we propose that nanostructure nucleation is controlled by rhodochrosite surface dissolution, similar to the dissolution-precipitation mechanism proposed for carbonate mineral surface reconstruction in aqueous solution. To explain nanostructure growth in humid oxygen, a new Cabrera-Mott mechanism involving electron tunneling and solid-state diffusion is proposed.

The relation between Puelche wind and the occurrence of forest fires in Bio Bio region, Chile

International Nuclear Information System (INIS)

Inzunza, Juan Carlos

2009-01-01

This paper presents a study of the relation between Puelche wind and forest fires in the Bio Bio Region, Chile. To establish a relationship between Puelche wind and forest fire generation, different data analysis methods and statistics test were applied. The relation between the total number of fires in the season and the days with Puelche wind were not statistically significant. When analyzing daily averages of fires produced with and without Puelche wind for each season, the highest daily fire occurrence values were found when there is Puelche wind, indicating that this event produces a strong effect on the daily occurrence of fires since these increased by 90% in comparison to the days without Puelche wind. The results of the difference between the number of fires with and without Puelche wind with respect to the average number of total fires indicate that the days with Puelche wind surpass both the total and the average values for days without Puelche wind, confirming the strong effect that a Puelche wind day has on forest fires. The greatest number of fires produced with Puelche wind occurs in the Province of Concepcion. This Province is the most affected by Puelche wind conditions despite having the smallest surface area for the region studied. Still, it is the most populous province of the region and has the greatest surface area with forests and plantations with respect to its size. Consequently, Puelche wind is a factor that increases the occurrence of forest fires and favors their propagation.

The impact of particle size, relative humidity, and sulfur dioxide on iron solubility in simulated atmospheric marine aerosols.

Science.gov (United States)

Cartledge, Benton T; Marcotte, Aurelie R; Herckes, Pierre; Anbar, Ariel D; Majestic, Brian J

2015-06-16

Iron is a limiting nutrient in about half of the world's oceans, and its most significant source is atmospheric deposition. To understand the pathways of iron solubilization during atmospheric transport, we exposed size segregated simulated marine aerosols to 5 ppm sulfur dioxide at arid (23 ± 1% relative humidity, RH) and marine (98 ± 1% RH) conditions. Relative iron solubility increased as the particle size decreased for goethite and hematite, while for magnetite, the relative solubility was similar for all of the fine size fractions (2.5-0.25 μm) investigated but higher than the coarse size fraction (10-2.5 μm). Goethite and hematite showed increased solubility at arid RH, but no difference (p > 0.05) was observed between the two humidity levels for magnetite. There was no correlation between iron solubility and exposure to SO2 in any mineral for any size fraction. X-ray absorption near edge structure (XANES) measurements showed no change in iron speciation [Fe(II) and Fe(III)] in any minerals following SO2 exposure. SEM-EDS measurements of SO2-exposed goethite revealed small amounts of sulfur uptake on the samples; however, the incorporated sulfur did not affect iron solubility. Our results show that although sulfur is incorporated into particles via gas-phase processes, changes in iron solubility also depend on other species in the aerosol.

Estimating return periods of extreme values from relatively short time series of winds

Science.gov (United States)

Jonasson, Kristjan; Agustsson, Halfdan; Rognvaldsson, Olafur; Arfeuille, Gilles

2013-04-01

An important factor for determining the prospect of individual wind farm sites is the frequency of extreme winds at hub height. Here, extreme winds are defined as the value of the highest 10 minutes averaged wind speed with a 50 year return period, i.e. annual exceeding probability of 2% (Rodrigo, 2010). A frequently applied method to estimate winds in the lowest few hundred meters above ground is to extrapolate observed 10-meter winds logarithmically to higher altitudes. Recent study by Drechsel et al. (2012) showed however that this methodology is not as accurate as interpolating simulated results from the global ECMWF numerical weather prediction (NWP) model to the desired height. Observations of persistent low level jets near Colima in SW-Mexico also show that the logarithmic approach can give highly inaccurate results for some regions (Arfeuille et al., 2012). To address these shortcomings of limited, and/or poorly representative, observations and extrapolations of winds one can use NWP models to dynamically scale down relatively coarse resolution atmospheric analysis. In the case of limited computing resources one has typically to make a compromise between spatial resolution and the duration of the simulated period, both of which can limit the quality of the wind farm siting. A common method to estimate maximum winds is to fit an extreme value distribution (e.g. Gumbel, gev or Pareto) to the maximum values of each year of available data, or the tail of these values. If data are only available for a short period, e.g. 10 or 15 years, then this will give a rather inaccurate estimate. It is possible to deal with this problem by utilizing monthly or weekly maxima, but this introduces new problems: seasonal variation, autocorrelation of neighboring values, and increased discrepancy between data and fitted distribution. We introduce a new method to estimate return periods of extreme values of winds at hub height from relatively short time series of winds, simulated

Coronal mass ejections and disturbances in solar wind plasma parameters in relation with geomagnetic storms

International Nuclear Information System (INIS)

Verma, P L; Singh, Puspraj; Singh, Preetam

2014-01-01

Coronal Mass Ejections (CMEs) are the drastic solar events in which huge amount of solar plasma materials are ejected into the heliosphere from the sun and are mainly responsible to generate large disturbances in solar wind plasma parameters and geomagnetic storms in geomagnetic field. We have studied geomagnetic storms, (Dst ≤-75 nT) observed during the period of 1997-2007 with Coronal Mass Ejections and disturbances in solar wind plasma parameters (solar wind temperature, velocity, density and interplanetary magnetic field) .We have inferred that most of the geomagnetic storms are associated with halo and partial halo Coronal Mass Ejections (CMEs).The association rate of halo and partial halo coronal mass ejections are found 72.37 % and 27.63 % respectively. Further we have concluded that geomagnetic storms are closely associated with the disturbances in solar wind plasma parameters. We have determined positive co-relation between magnitudes of geomagnetic storms and magnitude of jump in solar wind plasma temperature, jump in solar wind plasma density, jump in solar wind plasma velocity and jump in average interplanetary magnetic field with co-relation co-efficient 0 .35 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma temperature, 0.19 between magnitude of geomagnetic storms and magnitude of jump in solar wind density, 0.34 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma velocity, 0.66 between magnitude of geomagnetic storms and magnitude of jump in average interplanetary magnetic field respectively. We have concluded that geomagnetic storms are mainly caused by Coronal Mass Ejections and disturbances in solar wind plasma parameters that they generate.

Relative Humidity and the Susceptibility of Austenitic Stainless Steel to Stress Corrosion Cracking in an impure Plutonium Oxide Environment

Energy Technology Data Exchange (ETDEWEB)

Zapp, P.; Duffey, J.; Lam, P.; Dunn, K.

2010-05-05

Laboratory tests to investigate the corrosivity of moist plutonium oxide/chloride salt mixtures on 304L and 316L stainless steel coupons showed that corrosion occurred in selected samples. The tests exposed flat coupons for pitting evaluation and 'teardrop' stressed coupons for stress corrosion cracking (SCC) evaluation at room temperature to various mixtures of PuO{sub 2} and chloride-bearing salts for periods up to 500 days. The exposures were conducted in sealed containers in which the oxide-salt mixtures were loaded with about 0.6 wt % water from a humidified helium atmosphere. Observations of corrosion ranged from superficial staining to pitting and SCC. The extent of corrosion depended on the total salt concentration, the composition of the salt and the moisture present in the test environment. The most significant corrosion was found in coupons that were exposed to 98 wt % PuO{sub 2}, 2 wt % chloride salt mixtures that contained calcium chloride and 0.6 wt% water. SCC was observed in two 304L stainless steel teardrop coupons exposed in solid contact to a mixture of 98 wt % PuO{sub 2}, 0.9 wt % NaCl, 0.9 wt % KCl, and 0.2 wt % CaCl{sub 2}. The cracking was associated with the heat-affected zone of an autogenous weld that ran across the center of the coupon. Cracking was not observed in coupons exposed to the headspace gas above the solid mixture, or in coupons exposed to other mixtures with either no CaCl{sub 2} or 0.92 wt% CaCl{sub 2}. SCC was present where the 0.6 wt % water content exceeded the value needed to fully hydrate the available CaCl{sub 2}, but was absent where the water content was insufficient. These results reveal the significance of the relative humidity in the austenitic stainless steels environment to their susceptibility to corrosion. The relative humidity in the test environment was controlled by the water loading and the concentration of the hydrating salts such as CaCl{sub 2}. For each salt or salt mixture there is a threshold

Polymer Optical Fibre Bragg Grating Humidity Sensor at 100ºC

DEFF Research Database (Denmark)

Woyessa, Getinet; Fasano, Andrea; Markos, Christos

2016-01-01

We have demonstrated a polymer optical fibre Bragg grating humidity sensor that can be operated up to 100ºC. The sensor has been fabricated from a polycarbonate (PC) microstructured polymer optical fibre Bragg grating (mPOFBG). PC mPOFBG gave a relative humidity (RH) sensitivity of 6.95±0.83 pm...

MoS2-modified ZnO quantum dots nanocomposite: Synthesis and ultrafast humidity response

International Nuclear Information System (INIS)

Ze, Lu; Yueqiu, Gong; Xujun, Li; Yong, Zhang

2017-01-01

Highlights: • MoS 2 @ZnO QDs composite structure was synthesized by two-steps methods. • Ultrafast humidity sensing response is achieved by MoS 2 @ZnO QDs humidity sensor. • Sensor performs excellent cycle stability from 11% to 95% RH. • Humidity sensor could detect wide humidity range (11–95%). - Abstract: In this work, ZnO quantum dots (QDs), layered MoS 2 and MoS 2 -modified ZnO QDs (MoS 2 @ZnO QDs) nanocomposite were synthesized and then applied as humidity sensor. The crystal structure, morphology and element distribution of ZnO QDs, MoS 2 and MoS 2 @ZnO QDs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectrometry, respectively. The humidity sensing characteristics of the MoS 2 and MoS 2 @ZnO QDs against various relative humidity were measured at room temperature. The results show that the MoS 2 @ZnO QDs sensor exhibits high sensitivity with an impedance variation of three or four orders of magnitude to relative humidity range of 11–95% and it exhibits a short response-recovery time (1 s for adsorption and 20 s for desorption) and excellent repeatability. The mechanisms of the excellent performance for humidity sensing of MoS 2 @ZnO QDs sensor were discussed based on its impedance properties. Our work could offer guidelines to design higher performance especially ultrafast humidity response sensor utilizing the nanocomposite structure with two dimensional material and QDs.

Validation and Spatiotemporal Distribution of GEOS-5-Based Planetary Boundary Layer Height and Relative Humidity in China

Science.gov (United States)

Si, Yidan; Li, Shenshen; Chen, Liangfu; Yu, Chao; Wang, Zifeng; Wang, Yang; Wang, Hongmei

2018-04-01

Few studies have specifically focused on the validation and spatiotemporal distribution of planetary boundary layer height (PBLH) and relative humidity (RH) data in China. In this analysis, continuous PBLH and surface-level RH data simulated from GEOS-5 between 2004 and 2012, were validated against ground-based observations. Overall, the simulated RH was consistent with the statistical data from meteorological stations, with a correlation coefficient of 0.78 and a slope of 0.9. However, the simulated PBLH was underestimated compared to LIDAR data by a factor of approximately two, which was primarily because of poor simulation in late summer and early autumn. We further examined the spatiotemporal distribution characteristics of two factors in four regions—North China, South China, Northwest China, and the Tibetan Plateau. The results showed that the annual PBLH trends in all regions were fairly moderate but sensitive to solar radiation and precipitation, which explains why the PBLH values were ranked in order from largest to smallest as follows: Tibetan Plateau, Northwest China, North China, and South China. Strong seasonal variation of the PBLH exhibited high values in summer and low values in winter, which was also consistent with the turbulent vertical exchange. Not surprisingly, the highest RH in South China and the lowest RH in desert areas of Northwest China (less than 30%). Seasonally, South China exhibited little variation, whereas Northwest China exhibited its highest humidity in winter and lowest humidity in spring, the maximum values in the other regions were obtained from July to September.

Thin plasma-polymerized layers of hexamethyldisiloxane for humidity sensor development

International Nuclear Information System (INIS)

Guermat, N.; Bellel, A.; Sahli, S.; Segui, Y.; Raynaud, P.

2009-01-01

The response of resistive-type sensors based on thin hexamethyldisiloxane layers to relative humidity (RH) was evaluated. Humidity sensitive layers were plasma polymerized at low frequency glow discharge using a capacitively coupled parallel plate reactor. The sensor design comprises the absorbing layer deposited on clean glass substrate with comb-shape aluminum electrodes (interdigitated structure). The change in electrical impedance of the sensing film was monitored as the device was exposed to humidity. The variation of the plasma-polymerization parameters resulted in different humidity sensing properties which could be correlated to the results of Fourier transform infrared spectroscopy (FTIR). The deposited films exhibited a detectable response to RH ranging from 30 to 95% with low hysteresis, good reproducibility and stability in long-term use. Films with a greater thickness showed a significant decrease in the humidity sensing capability. FTIR analysis revealed the presence of SiH bonding groups, which are frequently linked to the film density. The increase in the plasma discharge power induced also a significant decrease in the diffusion process of water vapor inside the sensitive layer bulk.

Endurance Wind Power : practical insights into small wind

International Nuclear Information System (INIS)

Hicks, D.

2008-01-01

This presentation discussed practical issues related to purchasing and installing small wind turbines in Canada. Wind power capacity can be estimated by looking at provincial wind maps as well as by seeking wind data at local airports. Wind resources are typically measured at heights of between 20 meters and 50 m. The height of a wind turbine tower can significantly increase the turbine's wind generating capacity. Turbine rotors should always be placed 30 feet higher than obstacles within 500 feet. Many provinces have now mandated utilities to accept renewable energy resources from grid-connected wind energy plants. Net billing systems are used to determine the billing relationship between power-producing consumers and the utilities who will buy the excess power and sell it to other consumers. Utilities are not yet mandated to purchase excess power, and it is likely that federal and provincial legislation will be needed to ensure that net billing systems continue to grow. Many Canadian municipalities have no ordinances related to wind turbine placements. Consumers interested in purchasing small wind turbines should ensure that the turbine has been certified by an accredited test facility and has an adequate safety system. The noise of the turbine as well as its power performance in relation to the purchaser's needs must also be considered. It was concluded that small wind turbines can provide a means for electricity consumers to reduce their carbon footprint and hedge against the inflationary costs of fossil-fuelled energy resources. tabs., figs

Aging Impairs Whole-Body Heat Loss in Women under Both Dry and Humid Heat Stress.

Science.gov (United States)

Notley, Sean R; Poirier, Martin P; Hardcastle, Stephen G; Flouris, Andreas D; Boulay, Pierre; Sigal, Ronald J; Kenny, Glen P

2017-11-01

This study was designed to determine whether age-related impairments in whole-body heat loss, which are known to exist in dry heat, also occur in humid heat in women. To evaluate this possibility, 10 young (25 ± 4 yr) and 10 older (51 ± 7 yr) women matched for body surface area (young, 1.69 ± 0.11; older, 1.76 ± 0.14 m, P = 0.21) and peak oxygen consumption (V˙O2peak) (young, 38.6 ± 4.6; older, 34.8 ± 6.6 mL·kg·min, P = 0.15) performed four 15-min bouts of cycling at a fixed metabolic heat production rate (300 W; equivalent to ~45% V˙O2peak), each separated by a 15-min recovery, in dry (35°C, 20% relative humidity) and humid heat (35°C, 60% relative humidity). Total heat loss (evaporative ± dry heat exchange) and metabolic heat production were measured using direct and indirect calorimetry, respectively. Body heat storage was measured as the temporal summation of heat production and loss. Total heat loss was lower in humid conditions compared with dry conditions during all exercise bouts in both groups (all P body heat storage in young and older women, respectively (both P body heat storage was 29% and 16% greater in older women compared with young women in dry and humid conditions, respectively (both P < 0.05). Increasing ambient humidity reduces heat loss capacity in young and older women. However, older women display impaired heat loss relative to young women in both dry and humid heat, and may therefore be at greater risk of heat-related injury during light-to-moderate activity.

Analysis of heat transfer and frost layer formation on a cryogenic tank wall exposed to the humid atmospheric air

International Nuclear Information System (INIS)

Kim, Kyoung-Hoon; Ko, Hyung-Jong; Kim, Kyoungjin; Kim, Yong-Wook; Cho, Kie-Joo

2009-01-01

In this paper heat transfer characteristics and frost layer formation are investigated numerically on the surface of a cryogenic oxidizer tank for a liquid propulsion rocket, where a frost layer could be a significant factor in maintaining oxidizer temperature within a required range. Frost formation is modeled by considering mass diffusion of water vapor in the air into the frost layer and various heat transfer modes such as natural and forced convection, latent heat, solar radiation of short wavelength, and ambient radiation of long wavelength. Computational results are first compared with the available measurements and show favorable agreement on thickness and effective thermal conductivity of the frost layer. In the case of the cryogenic tank, a series of parametric studies is presented in order to examine the effects of important parameters such as temperature and wind speed of ambient air, air humidity, and tank wall temperature on the frost layer formation and the amount of heat transfer into the tank. It is found that the heat transfer by solar radiation is significant and also that heat transfer strongly depends on air humidity, ambient air temperature, and wind speed but not tank wall temperature.

Far offshore wind conditions in scope of wind energy

NARCIS (Netherlands)

Holtslag, M.C.

2016-01-01

Far offshore atmospheric conditions are favourable for wind energy purposes since mean wind speeds are relatively high (i.e., high power production) while turbulence levels are relatively low (i.e., less fatigue loads) compared to onshore conditions. Offshore wind energy, however, is still expensive

Field test of an all-semiconductor laser-based coherent continuous-wave Doppler lidar for wind energy applications

DEFF Research Database (Denmark)

Sjöholm, Mikael; Dellwik, Ebba; Hu, Qi

-produced all-semiconductor laser. The instrument is a coherent continuous-wave lidar with two fixed-focus telescopes for launching laser beams in two different directions. The alternation between the telescopes is achieved by a novel switching technique without any moving parts. Here, we report results from...... signal strength from external atmospheric parameters such as relative humidity and concentrations of atmospheric particles is discussed. This novel lidar instrument design seems to offer a promising low-cost alternative for prevision remote sensing of wind turbine inflow....

Formaldehyde emissions from ULEF- and NAF-bonded commercial hardwood plywood as influenced by temperature and relative humidity

Science.gov (United States)

Charles R. Frihart; James M. Wescott; Michael J. Birkeland; Kyle M. Gonner

2010-01-01

It is well documented in the literature that temperature and humidity can influence formaldehyde emissions from composite panels that are produced using urea-formaldehyde (UF) adhesives. This work investigates the effect of temperature and humidity on newer, ultra-low emitting formaldehyde urea formaldehyde (ULEF-UF) and no-added formaldehyde (NAF) adhesives. A...

Population growth and development of the psocid Liposcelis brunnea (Psocoptera: Liposcelididae) at constant temperatures and relative humidities.

Science.gov (United States)

Opit, G P; Throne, J E

2009-06-01

We studied the effects of temperature and relative humidity on population growth and development of the psocid Liposcelis brunnea Motschulsky. L. brunnea did not survive at 43% RH, but populations increased from 22.5 to 32.5 degrees C and 55-75% RH. Interestingly, we found population growth was higher at 63% RH than at 75% RH, and the greatest population growth was recorded at 32.5 degrees C and 63% RH. At 35 degrees C, L. brunnea nymphal survivorship was 33%, and populations declined or barely grew. L. brunnea males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 13, 82, and 5%, respectively. Female L. brunnea have three to five instars, and the percentages of females with three, four, and five instars were 18, 78, and 4%, respectively. The life cycle was shorter for males than females. We developed temperature-dependent development equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages and nymphal survivorship. The ability of L. brunnea to multiply rather rapidly at 55% RH may allow it to thrive under conditions of low relative humidity where other Liposcelis species may not. These data give us a better understanding of L. brunnea population dynamics and can be used to help develop effective management strategies for this psocid.

Wind-related orientation patterns in diurnal, crepuscular and nocturnal high-altitude insect migrants

Directory of Open Access Journals (Sweden)

Gao eHu

2016-02-01

Full Text Available Most insect migrants fly at considerable altitudes (hundreds of meters above the ground where they utilize fast-flowing winds to achieve rapid and comparatively long-distance transport. The nocturnal aerial migrant fauna has been well studied with entomological radars, and many studies have demonstrated that flight orientations are frequently grouped around a common direction in a range of nocturnal insect migrants. Common orientation typically occurs close to the downwind direction (thus ensuring that a large component of the insects’ self-powered speed is directed downstream, and in nocturnal insects at least, the downwind headings are seemingly maintained by direct detection of wind-related turbulent cues. Despite being far more abundant and speciose, the day-flying windborne migrant fauna has been much less studied by radar; thus the frequency of wind-related common orientation patterns and the sensory mechanisms involved in their formation remain to be established. Here we analyze a large dataset of >600,000 radar-detected ‘medium-sized’ windborne insect migrants (body mass from 10 to 70 mg, flying hundreds of meters above southern UK, during the afternoon, in the period around sunset, and in the middle of the night. We found that wind-related common orientation was almost ubiquitous during the day (present in 97% of all ‘migration events’ analyzed, and was also frequent at sunset (85% and at night (81%. Headings were systematically offset to the right of the flow at night-time (as predicted from the use of turbulence cues for flow assessment, but there was no directional bias in the offsets during the day or at sunset. Orientation ‘performance’ significantly increased with increasing flight altitude throughout the day and night. We conclude by discussing sensory mechanisms which most likely play a role in the selection and maintenance of wind-related flight headings.

Reindeer habitat use in relation to two small wind farms, during preconstruction, construction, and operation.

Science.gov (United States)

Skarin, Anna; Alam, Moudud

2017-06-01

Worldwide there is a rush toward wind power development and its associated infrastructure. In Fennoscandia, large-scale wind farms comprising several hundred windmills are currently built in important grazing ranges used for Sámi reindeer husbandry. In this study, reindeer habitat use was assessed using reindeer fecal pellet group counts in relation to two relatively small wind farms, with 8 and 10 turbines, respectively. In 2009, 1,315 15-m 2 plots were established and pellet groups were counted and cleaned from the plots. This was repeated once a year in May, during preconstruction, construction, and operation of the wind farms, covering 6 years (2009-2014) of reindeer habitat use in the area. We modeled the presence/absence of any pellets in a plot at both the local (wind farm site) and regional (reindeer calving to autumn range) scale with a hierarchical logistic regression, where spatial correlation was accounted for via random effects, using vegetation type, and the interaction between distance to wind turbine and time period as predictor variables. Our results revealed an absolute reduction in pellet groups by 66% and 86% around each wind farm, respectively, at local scale and by 61% at regional scale during the operation phase compared to the preconstruction phase. At the regional, scale habitat use declined close to the turbines in the same comparison. However, at the local scale, we observed increased habitat use close to the wind turbines at one of the wind farms during the operation phase. This may be explained by continued use of an important migration route close to the wind farm. The reduced use at the regional scale nevertheless suggests that there may be an overall avoidance of both wind farms during operation, but further studies of reindeer movement and behavior are needed to gain a better understanding of the mechanisms behind this suggested avoidance.

Satellite winds as a tool for offshore wind resource assessment: The Great Lakes Wind Atlas

DEFF Research Database (Denmark)

Doubrawa, Paula; Barthelmie, Rebecca Jane; Pryor, Sara C.

2015-01-01

and combine all scenes into one wind speed map. QuikSCAT winds undergo a seasonal correction due to lack of data during the cold season that is based on its ratio relative to buoy time series. All processing steps reduce the biases of the individual maps relative to the buoy observed wind climates. The remote...

Daily indoor-to-outdoor temperature and humidity relationships: a sample across seasons and diverse climatic regions.

Science.gov (United States)

Nguyen, Jennifer L; Dockery, Douglas W

2016-02-01

The health consequences of heat and cold are usually evaluated based on associations with outdoor measurements collected at a nearby weather reporting station. However, people in the developed world spend little time outdoors, especially during extreme temperature events. We examined the association between indoor and outdoor temperature and humidity in a range of climates. We measured indoor temperature, apparent temperature, relative humidity, dew point, and specific humidity (a measure of moisture content in air) for one calendar year (2012) in a convenience sample of eight diverse locations ranging from the equatorial region (10 °N) to the Arctic (64 °N). We then compared the indoor conditions to outdoor values recorded at the nearest airport weather station. We found that the shape of the indoor-to-outdoor temperature and humidity relationships varied across seasons and locations. Indoor temperatures showed little variation across season and location. There was large variation in indoor relative humidity between seasons and between locations which was independent of outdoor airport measurements. On the other hand, indoor specific humidity, and to a lesser extent dew point, tracked with outdoor, airport measurements both seasonally and between climates, across a wide range of outdoor temperatures. These results suggest that, in general, outdoor measures of actual moisture content in air better capture indoor conditions than outdoor temperature and relative humidity. Therefore, in studies where water vapor is among the parameters of interest for examining weather-related health effects, outdoor measurements of actual moisture content can be more reliably used as a proxy for indoor exposure than the more commonly examined variables of temperature and relative humidity.

Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels

Directory of Open Access Journals (Sweden)

Sang Soon Hwang

2009-11-01

Full Text Available In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, with simple micro parallel flow channels. It is known that the humidity at the cathode flow channel becomes very important for enhancing the ion conductivity of polymer membrane because fully humidified condition was normally set at anode. To investigate the effect of humidity on the performance of a fuel cell, in this study humidification was set to 100% at the anode flow channel and was changed by 0–100% at the cathode flow channel. Results showed that the maximum power density could be obtained under 60% humidified condition at the cathode where oxygen concentration was moderately high while maintaining high ion conductivity at a membrane.

Bird Movements and Behaviors in the Gulf Coast Region: Relation to Potential Wind-Energy Developments

Energy Technology Data Exchange (ETDEWEB)

Morrison, M. L.

2006-06-01

The purpose of this paper is to discuss the possible impacts of wind development to birds along the lower Gulf Coast, including both proposed near-shore and offshore developments. The report summarizes wind resources in Texas, discusses timing and magnitude of bird migration as it relates to wind development, reviews research that has been conducted throughout the world on near- and offshore developments, and provides recommendations for research that will help guide wind development that minimizes negative impacts to birds and other wildlife resources.

Exploring the effects of symmetrical and asymmetrical relative humidity on the performance of H{sub 2}/air PEM fuel cell at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Saleh, Mahmoud M.; Okajima, Takeoshi; Kitamura, Fusao; Ohsaka, Takeo [Department of Electronic Chemistry, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Hayase, Masahiko [Development Department, NF Co., 6-3-20 Tsunashima-higashi, Kohoku-ku, Yokohama 223-8508 (Japan)

2007-02-10

This article is dedicated to study the interlinked effects of symmetric relative humidity (RH), and asymmetric RH on the performance of H{sub 2}/air PEM fuel cell at different temperatures. The symmetric and asymmetric RH were achieved by setting the cathode relative humidity (RHC) and anode relative humidity (RHA) as equal and unequal values, respectively. The cell performance was evaluated by collecting polarization curves of the cell at different RH, RHC and RHA and at different cell temperatures (T{sub cell}). The polarization curves along with the measured internal cell resistance (membrane resistance) were discussed in the light of the present fuel cell theory. The results showed that symmetric relative humidity has different impacts depending on the cell temperature. While at RH of 35% the cell can show considerable performance at T{sub cell} = 70 C, it is not so at T{sub cell} = 90 C. At T{sub cell} = 70 C, the cell potential increases with RH at lower and medium current densities but decreases with RH at higher currents. This was attributed to the different controlling processes at higher and lower current densities. This trend at 70 C is completely destroyed at 90 C. Operating our PEM fuel cell at dry H{sub 2} gas conditions (RHA = 0%) is not detrimental as operating the cell at dry Air (O{sub 2}) conditions (RHC = 0%). At RHA = 0% and humidified air, water transport by back diffusion from the cathode to the anode at the employed experimental conditions can support reasonable rehydration of the membrane and catalysts. At RHA = 0, a possible minimum RHC for considerable cell operation is temperature dependent. At RHC = 0 conditions, the cell can operate only at RHA = 100% with a loss that depends on T{sub cell}. It was found that the internal cell resistance depends on RH, RHA, RHC and T{sub cell} and it is consistent with the observed cell performance. (author)

3D WindScanner lidar measurements of wind and turbulence around wind turbines, buildings and bridges

Science.gov (United States)

Mikkelsen, T.; Sjöholm, M.; Angelou, N.; Mann, J.

2017-12-01

WindScanner is a distributed research infrastructure developed at DTU with the participation of a number of European countries. The research infrastructure consists of a mobile technically advanced facility for remote measurement of wind and turbulence in 3D. The WindScanners provide coordinated measurements of the entire wind and turbulence fields, of all three wind components scanned in 3D space. Although primarily developed for research related to on- and offshore wind turbines and wind farms, the facility is also well suited for scanning turbulent wind fields around buildings, bridges, aviation structures and of flow in urban environments. The mobile WindScanner facility enables 3D scanning of wind and turbulence fields in full scale within the atmospheric boundary layer at ranges from 10 meters to 5 (10) kilometers. Measurements of turbulent coherent structures are applied for investigation of flow pattern and dynamical loads from turbines, building structures and bridges and in relation to optimization of the location of, for example, wind farms and suspension bridges. This paper presents our achievements to date and reviews briefly the state-of-the-art of the WindScanner measurement technology with examples of uses for wind engineering applications.

A Correction Method for UAV Helicopter Airborne Temperature and Humidity Sensor

Directory of Open Access Journals (Sweden)

Longqing Fan

2017-01-01

Full Text Available This paper presents a correction method for UAV helicopter airborne temperature and humidity including an error correction scheme and a bias-calibration scheme. As rotor downwash flow brings measurement error on helicopter airborne sensors inevitably, the error correction scheme constructs a model between the rotor induced velocity and temperature and humidity by building the heat balance equation for platinum resistor temperature sensor and the pressure correction term for humidity sensor. The induced velocity of a spatial point below the rotor disc plane can be calculated by the sum of the induced velocities excited by center line vortex, rotor disk vortex, and skew cylinder vortex based on the generalized vortex theory. In order to minimize the systematic biases, the bias-calibration scheme adopts a multiple linear regression to achieve a systematically consistent result with the tethered balloon profiles. Two temperature and humidity sensors were mounted on “Z-5” UAV helicopter in the field experiment. Overall, the result of applying the calibration method shows that the temperature and relative humidity obtained by UAV helicopter closely align with tethered balloon profiles in providing measurements of the temperature profiles and humidity profiles within marine atmospheric boundary layers.

Improved running performance in hot humid conditions following whole body precooling.

Science.gov (United States)

Booth, J; Marino, F; Ward, J J

1997-07-01

On two separate occasions, eight subjects controlled speed to run the greatest distance possible in 30 min in a hot, humid environment (ambient temperature 32 degrees C, relative humidity 60%). For the experimental test (precooling), exercise was preceeded by cold-water immersion. Precooling increased the distance run by 304 +/- 166 m (P body temperature decreased from 36.5 +/- 0.1 degrees C to 33.8 +/- 0.2 degrees C following precooling (P body sweating are not different between tests. In conclusion, water immersion precooling increased exercise endurance in hot, humid conditions with an enhanced rate of heat storage and decreased thermoregulatory strain.

Prediction of Fog/Visibility over India using NWP Model

Indian Academy of Sciences (India)

54

fog which is driven by NWP model forecast of surface relative humidity and wind speed. The performance of NWP model forecast of visibility is found comparable to that from simple fog model driven by NWP forecast of relative humidity and wind speed. Keywords: Visibility, Fog, Insat-3D, METARS, NCUM, North India.

Separation of dry and wet periods from regular weather station data for the analysis of wind erosion risk

DEFF Research Database (Denmark)

Naeini, Mohammadali Saremi; Fister, Wolfgang; Heckrath, Goswin Johann

importance, soil moisture content is often ignored in the analysis of wind data for wind erosion studies. The main reason most probably being the lack of soil moisture sensors in conventional climate stations. Soil moisture at a given point in time is determined by rain (e.g. rainfall amount, duration......), climate (e.g. air temperature, solar radiation, evaporation) and soil (e.g. infiltration rate, adhesion). The purpose of this study is to overcome the lack of soil moisture data for wind erosion risk assessment by developing a method to estimate the soil wetness based on easy available weather data......, such as daily precipitation, hourly/sub hourly ambient air temperature and hourly/sub hourly relative humidity. This new method was used to identify periods of wet and dry soil moisture conditions of a time series from 20 weather stations in Denmark. The length of the time series varied between 8 to 37 years...

Fiber optic humidity sensor using water vapor condensation.

Science.gov (United States)

Limodehi, Hamid E; Légaré, François

2017-06-26

The rate of vapor condensation on a solid surface depends on the ambient relative humidity (RH). Also, surface plasmon resonance (SPR) on a metal layer is sensitive to the refractive index change of its adjacent dielectric. The SPR effect appears as soon as a small amount of moisture forms on the sensor, resulting in a decrease in the amount of light transmitted due to plasmonic loss. Using this concept, we developed a fiber optic humidity sensor based on SPR. It can measure the ambient RH over a dynamic range from 10% to 85% with an accuracy of 3%.

Humidity influence on the adhesion of SU-8 polymer from MEMS applications

Directory of Open Access Journals (Sweden)

Birleanu Corina

2017-01-01

Full Text Available In this paper, the adhesion behaviors of SU-8 polymer thin film from MEMS application were investigated as a function of relative humidity. The adhesion test between the AFM tip and SU-8 polymer have been extensively studied using the atomic force microscope (AFM, for a relative humidity (RH varying between 20 and 90%. The samples for tests are SU-8 polymers hard baked at different temperatures. The hard bake temperature changes the tribo-mechanical properties of polymers. The paper reports the measurements and the modeling of adhesion forces versus humidity in controlled ranges between 20 to 90%RH. To investigate the effect of relative humidity on adhesion for SU-8 polymer hard baked we used an analytical method which encompasses the effect of capillarity as well as the solid-to-solid interaction. While the capillary force expression is considered to be the sum of the superficial tension and the Laplace force for the solid-solid interaction is expressed by the Derjagin, Muller and Toropov (DMT model of solids adhesion. The analytical results obtained are in accordance with those obtained experimentally.

Effect of Humidity in Air on Performance and Long-Term Durability of SOFCs

DEFF Research Database (Denmark)

Hagen, Anke; Chen, Ming; Neufeld, Kai

2009-01-01

Anode supported SOFCs based on Ni-YSZ anodes, YSZ electrolytes, and LSM-YSZ cathodes were studied with respect to durability in humid air (~4%) over typically 1500 hours. Operating temperature and current density were varied between 750 and 850 oC and 0.25-0.75 A/cm2, respectively. It was found...... that the introduction of humidity affected the cell voltage under polarization of the cell and that this effect was (at least partly) reversible upon switching off the humidity, probably related to a segregation of impurities towards the three phase boundary in the presence of humidity. Generally, the studied cells...... were successfully operated in humid air under technologically relevant conditions. Improvements at the cathode/electrolyte interface made it possible to obtain highly stable cells, which can be operated under high current density and at 750 oC in humid air - conditions that are known to cause...

Sealed Attics Exposed to Two Years of Weathering in a Hot and Humid Climate

Energy Technology Data Exchange (ETDEWEB)

Miller, William A [ORNL; Railkar, Sudhir [GAF; Shiao, Ming C [ORNL; Desjarlais, Andre Omer [ORNL

2016-01-01

Field studies in a hot, humid climate were conducted to investigate the thermal and hygrothermal performance of ventilated attics and non-ventilated semi-conditioned attics sealed with open-cell and with closed-cell spray polyurethane foam insulation. Moisture pin measurements made in the sheathing and absolute humidity sensor data from inside the foam and from the attic air show that moisture is being stored in the foam. The moisture in the foam diffuses to and from the sheathing dependent on the pressure gradient at the foam-sheathing interface which is driven by the irradiance and night-sky radiation. Ventilated attics in the same hot, humid climate showed less moisture movement in the sheathing than those sealed with either open- or closed-cell spray foam. In the ventilated attics the relative humidity drops as the attic air warms; however, the opposite was observed in the sealed attics. Peaks in measured relative humidity in excess of 80 90% and occasionally near saturation (i.e., 100%) were observed from solar noon till about 8 PM on hot, humid days. The conditioned space of the test facility is heated and cooled by an air-to-air heat pump. Therefore the partial pressure of the indoor air during peak irradiance is almost always less than that observed in the sealed attics. Field data will be presented to bring to light the critical humidity control issues in sealed attics exposed to hot, humid climates.

A CMOS smart temperature and humidity sensor with combined readout.

Science.gov (United States)

Eder, Clemens; Valente, Virgilio; Donaldson, Nick; Demosthenous, Andreas

2014-09-16

A fully-integrated complementary metal-oxide semiconductor (CMOS) sensor for combined temperature and humidity measurements is presented. The main purpose of the device is to monitor the hermeticity of micro-packages for implanted integrated circuits and to ensure their safe operation by monitoring the operating temperature and humidity on-chip. The smart sensor has two modes of operation, in which either the temperature or humidity is converted into a digital code representing a frequency ratio between two oscillators. This ratio is determined by the ratios of the timing capacitances and bias currents in both oscillators. The reference oscillator is biased by a current whose temperature dependency is complementary to the proportional to absolute temperature (PTAT) current. For the temperature measurement, this results in an exceptional normalized sensitivity of about 0.77%/°C at the accepted expense of reduced linearity. The humidity sensor is a capacitor, whose value varies linearly with relative humidity (RH) with a normalized sensitivity of 0.055%/% RH. For comparison, two versions of the humidity sensor with an area of either 0.2 mm2 or 1.2 mm2 were fabricated in a commercial 0.18 μm CMOS process. The on-chip readout electronics operate from a 5 V power supply and consume a current of approximately 85 µA.

Wind farm project economics : value of wind

Energy Technology Data Exchange (ETDEWEB)

Bills-Everett, T. [Mainstream Renewable Power, Toronto, ON (Canada)

2010-07-01

This PowerPoint presentation discussed methods of increasing the value of wind power projects. Appropriate turbine selection and layout is needed to ensure that wind resources are fully developed. Construction costs have a significant impact on project costs. The world turbine price index has not significantly fluctuated since 2006. Operating costs, and the value of wind power projects, are linked with OPEX fluctuations. Wind power projects can significantly reduce greenhouse gas (GHG) emissions. An increase in wind power capacity will reduce the overall cost of energy produced from wind power. Countries can use wind power as part of a renewable energy portfolio designed to reduce risks related to diminishing petroleum supplies. Wind power will help to ensure a global transition to renewable energy use. tabs., figs.

Hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil

Directory of Open Access Journals (Sweden)

THIAGO R. RODRIGUES

Full Text Available ABSTRACT Matter and energy flux dynamics of wetlands are important to understand environmental processes that govern biosphere-atmosphere interactions across ecosystems. This study presents analyses about hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil. This study was conducted in Private Reserve of Natural Heritage (PRNH SESC, 16º39'50''S; 56º47'50''W in Brazilian Wetland. According to Curado et al. (2012, the wet season occurs between the months of January and April, while the June to September time period is the dry season. Results presented same patterns in energies fluxes in all period studied. Wind speed and air temperature presented same patterns, while LE was relative humidity presented inverse patterns of the air temperature. LE was predominant in all seasons and the sum of LE and H was above 90% of net radiation. Analyses of linear regression presented positive interactions between wind speed and LE, and wind speed and H in all seasons, except in dry season of 2010. Confidence coefficient regression analyses present statistical significance in all wet and dry seasons, except dry season of 2010, suggest that LE and H had interaction with other micrometeorological variables.

Impact of small variations in temperature and humidity on the reproductive activity and survival of Aedes aegypti (Diptera, Culicidae)

International Nuclear Information System (INIS)

Costa, Ethiene Arruda Pedrosa de Almeida; Santos, Eloina Maria de Mendonca; Correia, Juliana Cavalcanti; Albuquerque, Cleide Maria Ribeiro de

2010-01-01

In short space of time increase in temperature and rainfall can affect vector populations and, consequently, the diseases for them transmitted. The present study analyzed the effect of small temperature and humidity variations on the fecundity, fertility and survival of Aedes aegypti. These parameters were analyzed using individual females at temperatures ranging from 23 to 27 deg C (mean 25 deg C); 28 to 32 deg C (mean 30 deg C) and 33 to 37 deg C (mean 35 deg C) associated to 60 +- 8% and 80 +- 6% relative humidity. Females responded to an increase in temperature by reducing egg production, oviposition time and changing oviposition patterns. At 25 deg C and 80% relative humidity, females survived two-fold more and produced 40% more eggs when compared to those kept at 35 deg C and 80% relative humidity. However, in 45% of females kept at 35 deg C and 60% relative humidity oviposition was inhibited and only 15% females laid more than 100 eggs, suggesting that the intensity of the temperature effect was influenced by humidity. Gradual reductions in egg fertility at 60% relative humidity were observed with the increase in temperature, although such effect was not found in the 80% relative humidity at 25 deg C and 30 deg C. These results suggest that the reduction in population densities recorded in tropical areas during seasons when temperatures reach over 35 deg C is likely to be strongly influenced by temperature and humidity, with a negative effect on several aspects of mosquito biology. (author)

Absorbing aerosols at high relative humidity: linking hygroscopic growth to optical properties

Directory of Open Access Journals (Sweden)

J. Michel Flores

2012-06-01

Full Text Available One of the major uncertainties in the understanding of Earth's climate system is the interaction between solar radiation and aerosols in the atmosphere. Aerosols exposed to high humidity will change their chemical, physical, and optical properties due to their increased water content. To model hydrated aerosols, atmospheric chemistry and climate models often use the volume weighted mixing rule to predict the complex refractive index (RI of aerosols when they interact with high relative humidity, and, in general, assume homogeneous mixing. This study explores the validity of these assumptions. A humidified cavity ring down aerosol spectrometer (CRD-AS and a tandem hygroscopic DMA (differential mobility analyzer are used to measure the extinction coefficient and hygroscopic growth factors of humidified aerosols, respectively. The measurements are performed at 80% and 90%RH at wavelengths of 532 nm and 355 nm using size-selected aerosols with different degrees of absorption; from purely scattering to highly absorbing particles. The ratio of the humidified to the dry extinction coefficients (fRH_ext(%RH, Dry is measured and compared to theoretical calculations based on Mie theory. Using the measured hygroscopic growth factors and assuming homogeneous mixing, the expected RIs using the volume weighted mixing rule are compared to the RIs derived from the extinction measurements.

We found a weak linear dependence or no dependence of fRH(%RH, Dry with size for hydrated absorbing aerosols in contrast to the non-monotonically decreasing behavior with size for purely scattering aerosols. No discernible difference could be made between the two wavelengths used. Less than 7% differences were found between the real parts of the complex refractive indices derived and those calculated using the volume weighted mixing rule, and the imaginary parts had up to a 20% difference. However, for substances with growth factor less than 1

Atmospheric balance of the humidity and estimate of the precipitation recycled in Colombia according to the re-analysis NCEP/NCAR

International Nuclear Information System (INIS)

Cuartas, Adriana; Poveda, German

2002-01-01

The magnitudes of the entrance humidity flows and exit are considered and the amount of precipitable water at different levels from the atmospheric column on Colombia. The water balance is quantified in the Colombian atmosphere; the regions and the atmospheric levels of entrance and exit of humidity are identified. The hypothesis that in the long term the net atmospheric humidity influence must be equal to the average of long term of the net run-off is verified. In addition, the percentage of recycled precipitation is considered on the Colombian territory. The variability during the two phases of the ENSO is analyzed. The calculations are made with the information of the climatic project Reanalysis developed by the National Center for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR), with the collaboration of the National Oceanic and Atmospheric Administration (NOAA)/National Environmental Satellite of the U.S.A. For this work it was counted on monthly information of 41 years between 1958-1998. The hydrological information was obtained from the project Balances Hidrologicos de Colombia, 1999, made by the Posgrado de Recursos Hidraulicos, de la Universidad Nacional, with the support of COLCIENCIAS and the Unidad de Planeacion Minero Energetica-UPME. The results showed the average value of the net influence of humidity to the atmosphere of Colombia is of 5716 mm/year, with a great variability in both phases of the ENSO. The greater humidity advection towards Colombia occurs in the low levels of pressure (between 1000 and 850 hPa), and originating of all the directions, mainly of trade winds of the east and trade winds of the west. Also one was that the greater humidity transport towards Colombia occurs in trimesters DJF and MAM, with average values 505,1 and 606,6 mm/year, respectively. It was observed that the hypothesis that in the long term, the net atmospheric flux, is equal to the net terrestrial run-off, reasonably is adapted for

A Resistive Humidity Sensor Based on Nanostructured WO3-ZnO Composites

Directory of Open Access Journals (Sweden)

Karunesh Tiwari

2011-11-01

Full Text Available Paper reports morphological and humidity sensing studies of WO3 and WO3-ZnO composite pellets prepared in the weight % ratio of 10:1, 4:1 and 2:1 by solid-state reaction route. The pellets have been annealed at temperatures of 300-500 °C. XRD pattern shows peaks of ZnWO4 formed due to solid state reaction between WO3 and ZnO. SEM micrographs show that the sensing elements manifest porous structure. Granulation and tendency to agglomerate seen in the SEM micrograph are due to the presence of zinc ions in ZnWO4. Nanoparticles are having their sizes in the range 37-182 nm. The average Kelvin radius at 20˚C room temperature is 27 Ả. Humidity sensing application of the pellets has been studied in a humidity control cabinet. It is observed that as relative humidity increases, there is decrease in the resistance of pellets in the range 10-85 % RH. Sensing element of WO3-ZnO in 2:1 weight % ratio shows best results in 10-85 % relative humidity range. The average sensitivity of this sample is 1.25 MΩ/%RH. This sensing element shows good reproducibility, low hysteresis and less effect of aging.

Calibration and validation processes for relative humidity measurement by a Hygrochron iButton.

Science.gov (United States)

Shin, Mirim; Patton, Raymond; Mahar, Trevor; Ireland, Angus; Swan, Paul; Chow, Chin Moi

2017-10-01

Accurate relative humidity (RH) measurement is demanded in studies of thermal comfort. Thermal discomfort occurs when the near-to-skin temperature or RH is outside of the thermal comfort zone. The Hygrochron, a small wireless device which measures both temperature and RH, would be suitable and convenient in exercise or sleep studies. However, the RH measurement has not been validated. This paper has three parts. Part 1: In evaluating the sensor surface for RH detection, four Hygrochrons were placed on a wet paper towel. Two were placed on the towel with the protruding surface facing up and the other two facing down. The results showed that the Hygrochron with the protruding side was the sensor surface for detecting RH. Part 2: Twenty-seven Hygrochrons were calibrated in a humidity calibration chamber at a RH range from 40 to 90% at a constant temperature from 32 to 37°C. The mean bias was -1.08% between the Hygrochrons and the calibration chamber. The Hygrochron overestimated RH at the lower range (40-60%) and underestimated RH at the higher range (80-90%). The application of individual regression equations to each Hygrochron improved accuracy and reduced the mean bias to -0.002%. However, one Hygrochron showed outlier values that may be due to a manufacturing defect. Part 3: The reproducibility of Hygrochron for RH measurements was tested twice at the same condition of 35°C over a three-month interval. The intra-class coefficient was 0.996 to 1.000 with non-significant differences in the mean RH between test and re-test results (p=0.159). Hygrochrons are valid for RH measurements which show high reproducibility. It is recommended that Hygrochrons be calibrated over a range of desired RH and temperature prior to use to improve accuracy and detect any manufacturing defects. Copyright © 2017 Elsevier Inc. All rights reserved.

Graphene based humidity-insensitive films

KAUST Repository

Tai, Yanlong; Lubineau, Gilles

2017-01-01

A humidity nonsensitive material based on reduced-graphene oxide (r-GO) and methods of making the same are provided, in an embodiment, the materia! has a resistance/humidity variation of about -15% to 15% based on different sintering time

Kinetically Determined Hygroscopicity and Efflorescence of Sucrose-Ammonium Sulfate Aerosol Droplets under Lower Relative Humidity.

Science.gov (United States)

Wang, Lin-Na; Cai, Chen; Zhang, Yun-Hong

2017-09-14

Organic aerosols will likely form in semisolid, glassy, and high viscous state in the atmosphere, which show nonequilibrium kinetic characteristics at low relative humidity (RH) conditions. In this study, we applied optical tweezers to investigate the water transport in a sucrose/(NH 4 ) 2 SO 4 droplet with high organic to inorganic mole ratio (OIR). The characteristic time ratio between the droplet radius and the RH was used to describe the water mass transfer difference dependent on RH. For OIR greater than 1:1 in sucrose/(NH 4 ) 2 SO 4 droplets, the characteristic time ratio at low RH (∼60%). We also coupled vacuum FTIR spectrometer and a high-speed photography to study the efflorescence process in sucrose/(NH 4 ) 2 SO 4 droplets with low OIR. The crystalline fraction of (NH 4 ) 2 SO 4 was used to understand efflorescence behavior when the RH was linearly decreasing with a velocity of 1.2% RH min -1 . Because of suppression of (NH 4 ) 2 SO 4 nucleation by addition of sucrose, the efflorescence relative humidity (ERH) of (NH 4 ) 2 SO 4 decrease from the range of ∼48.2% to ∼36.1% for pure (NH 4 ) 2 SO 4 droplets to from ∼44.7% to ∼25.4%, from ∼43.2% to ∼21.2%, and from ∼41.7% to ∼21.1% for the mixed droplets with OIR of 1:4, 1:3, and 1:2, respectively. No crystallization was observed when the OIR is higher than 1:1. Suppression of (NH 4 ) 2 SO 4 crystal growth was also observed under high viscous sucrose/(NH 4 ) 2 SO 4 droplets at lower RH.

Humidity control of an incubator using the microcontroller-based active humidifier system employing an ultrasonic nebulizer.

Science.gov (United States)

Güler, I; Burunkaya, M

2002-01-01

Relative humidity levels of an incubator were measured and controlled. An ultrasonic nebulizer system as an active humidifier was used to humidify the incubator environment. An integrated circuit-type humidity sensor was used to measure the humidity level of the incubator environment. Measurement and control processes were achieved by a PIC microcontroller. The high-performance and high-speed PIC provided the flexibility of the system. The developed system can be used effectively for the intensive care of newborns and/or premature babies. Since the humidifier generates an aerosol in ambient conditions, it is possible to provide the high relative humidity level for therapeutic and diagnostic purposes in medicine.

Attitudes towards offshore wind farms-The role of beach visits on attitude and demographic and attitude relations

International Nuclear Information System (INIS)

Ladenburg, Jacob

2010-01-01

Presently, less than a handful of papers have analysed the attitude towards offshore wind farms in a population living in an area with offshore wind farms. This leaves the experience-based attitude and demographic relations analysis relatively unexplored. The present studies aims at covering some of that seemingly uncharted territory by analysing attitudes from a sample of more than 1000 respondents. Applying an Ordered Probit Model, the results show general positive attitudes towards offshore wind farms and that the attitude formation seems to be a function of the gender, income, level of education, visit frequency and type of visit to the beach and the view to on-land turbines from the residence. Interestingly and perhaps the most interesting results, the observed relations between demographics and attitude are found to be dependent on the type and frequency of usage of the beach among the respondents. Attitudes towards offshore wind farms and demographic associations are thus found to be more evident in the case that respondents do use not the beach for walking on a relatively frequent basis but much weaker if the respondent use the beach on a frequent basis. However, these results are sensitive to the type of beach usage. This suggests that attitude formation towards offshore wind farms appear to be dependent on a combination of the type and frequency of use of the beach. To the author's knowledge these findings are novel, as such relation has not yet been identified in the literature. As such, the results shed light on a new angle in both the literature focusing on the opposition formation towards wind power projects in general and offshore wind farms in particular.

Controlled humidity gas circulators

International Nuclear Information System (INIS)

Gruner, S.M.

1981-01-01

A programmable circulator capable of regulating the humidity of a gas stream over a wide range of humidity is described. An optical dew-point hygrometer is used as a feedback element to control the addition or removal of water vapor. Typical regulation of the gas is to a dew-point temperature of +- 0.2 0 C and to an accuracy limited by the dew-point hygrometer

A nafion coated capacitive humidity sensor on a flexible PET substrate

KAUST Repository

Sapsanis, Christos

2017-03-07

This paper reports a simple and low-cost technique for fabricating low-power capacitive humidity sensors without the use of a cleanroom environment. A maskless laser engraving system was utilized to fabricate two different gold electrode structures, interdigitated electrodes and Hilbert\\'s fifth-order fractal. The capacitive structures were implemented on a flexible PET substrate. The usage of Nafion, a well-known polymer for its hydrophilic properties as a sensing film, was attempted on the PET and outperformed the current efforts in flexible substrates. Its humidity sensing properties were evaluated in an automated gas setup with a relative humidity (RH %) ranging from 15% to 95 %.

A nafion coated capacitive humidity sensor on a flexible PET substrate

KAUST Repository

Sapsanis, Christos; Buttner, Ulrich; Omran, Hesham; Belmabkhout, Youssef; Shekhah, Osama; Eddaoudi, Mohamed; Salama, Khaled N.

2017-01-01

This paper reports a simple and low-cost technique for fabricating low-power capacitive humidity sensors without the use of a cleanroom environment. A maskless laser engraving system was utilized to fabricate two different gold electrode structures, interdigitated electrodes and Hilbert's fifth-order fractal. The capacitive structures were implemented on a flexible PET substrate. The usage of Nafion, a well-known polymer for its hydrophilic properties as a sensing film, was attempted on the PET and outperformed the current efforts in flexible substrates. Its humidity sensing properties were evaluated in an automated gas setup with a relative humidity (RH %) ranging from 15% to 95 %.

Night ventilation at courtyard housing estate in warm humid tropic for sustainable environment

Science.gov (United States)

Defiana, Ima; Teddy Badai Samodra, FX; Setyawan, Wahyu

2018-03-01

The problem in the night-time for warm humid tropic housing estate is thermal discomfort. Heat gains accumulation from building envelope, internal heat gains and activities of occupants influence indoor thermal comfort. Ventilation is needed for transfer or removes heat gains accumulation to outdoor. This study describes the role of an inner courtyard to promote pressure difference. Pressure difference as a wind driven force to promote wind velocity thereby could transfer indoor heat gains accumulation to outdoor of building. A simulation used as the research method for prediction wind velocity. Purposive sampling used as the method to choose building sample with similar inner courtyards. The field survey was conducted to obtain data of inner courtyard typologies and two housing were used as model simulation. Furthermore, the simulation is running in steady state mode, at 05.00 pm when the occupants usually close window. But the window should be opened in the night-time to transfer indoor heat gain to outdoor. The result shows that the factor influencing physiological cooling as consequences of inner courtyard are height to width ratio, the distance between inner courtyard to windward, window configuration and the inner courtyard design-the proportion between the length, the width, and the height.

Comparison of Single-Point and Continuous Sampling Methods for Estimating Residential Indoor Temperature and Humidity.

Science.gov (United States)

Johnston, James D; Magnusson, Brianna M; Eggett, Dennis; Collingwood, Scott C; Bernhardt, Scott A

2015-01-01

Residential temperature and humidity are associated with multiple health effects. Studies commonly use single-point measures to estimate indoor temperature and humidity exposures, but there is little evidence to support this sampling strategy. This study evaluated the relationship between single-point and continuous monitoring of air temperature, apparent temperature, relative humidity, and absolute humidity over four exposure intervals (5-min, 30-min, 24-hr, and 12-days) in 9 northern Utah homes, from March-June 2012. Three homes were sampled twice, for a total of 12 observation periods. Continuous data-logged sampling was conducted in homes for 2-3 wks, and simultaneous single-point measures (n = 114) were collected using handheld thermo-hygrometers. Time-centered single-point measures were moderately correlated with short-term (30-min) data logger mean air temperature (r = 0.76, β = 0.74), apparent temperature (r = 0.79, β = 0.79), relative humidity (r = 0.70, β = 0.63), and absolute humidity (r = 0.80, β = 0.80). Data logger 12-day means were also moderately correlated with single-point air temperature (r = 0.64, β = 0.43) and apparent temperature (r = 0.64, β = 0.44), but were weakly correlated with single-point relative humidity (r = 0.53, β = 0.35) and absolute humidity (r = 0.52, β = 0.39). Of the single-point RH measures, 59 (51.8%) deviated more than ±5%, 21 (18.4%) deviated more than ±10%, and 6 (5.3%) deviated more than ±15% from data logger 12-day means. Where continuous indoor monitoring is not feasible, single-point sampling strategies should include multiple measures collected at prescribed time points based on local conditions.

Statistical analysis of dispersion relations in turbulent solar wind fluctuations using Cluster data

Science.gov (United States)

Perschke, C.; Narita, Y.

2012-12-01

Multi-spacecraft measurements enable us to resolve three-dimensional spatial structures without assuming Taylor's frozen-in-flow hypothesis. This is very useful to study frequency-wave vector diagram in solar wind turbulence through direct determination of three-dimensional wave vectors. The existence and evolution of dispersion relation and its role in fully-developed plasma turbulence have been drawing attention of physicists, in particular, if solar wind turbulence represents kinetic Alfvén or whistler mode as the carrier of spectral energy among different scales through wave-wave interactions. We investigate solar wind intervals of Cluster data for various flow velocities with a high-resolution wave vector analysis method, Multi-point Signal Resonator technique, at the tetrahedral separation about 100 km. Magnetic field data and ion data are used to determine the frequency- wave vector diagrams in the co-moving frame of the solar wind. We find primarily perpendicular wave vectors in solar wind turbulence which justify the earlier discussions about kinetic Alfvén or whistler wave. The frequency- wave vector diagrams confirm (a) wave vector anisotropy and (b) scattering in frequencies.

Measuring tropospheric wind with microwave sounders

Science.gov (United States)

Lambrigtsen, B.; Su, H.; Turk, J.; Hristova-Veleva, S. M.; Dang, V. T.

2017-12-01

In its 2007 "Decadal Survey" of earth science missions for NASA the U.S. National Research Council recommended that a Doppler wind lidar be developed for a three-dimensional tropospheric winds mission ("3D-Winds"). The technology required for such a mission has not yet been developed, and it is expected that the next Decadal Survey, planned to be released by the end of 2017, will put additional emphasis on the still pressing need for wind measurements from space. The first Decadal Survey also called for a geostationary microwave sounder (GMS) on a Precipitation and All-weather Temperature and Humidity (PATH) mission, which could be used to measure wind from space. Such a sounder, the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR), has been developed at the Jet Propulsion Laboratory (JPL). The PATH mission has not yet been funded by NASA, but a low-cost subset of PATH, GeoStorm has been proposed as a hosted payload on a commercial communications satellite. Both PATH and GeoStorm would obtain frequent (every 15 minutes of better) measurements of tropospheric water vapor profiles, and they can be used to derive atmospheric motion vector (AMV) wind profiles, even in the presence of clouds. Measurement of wind is particularly important in the tropics, where the atmosphere is largely not in thermal balance and wind estimates cannot generally be derived from temperature and pressure fields. We report on simulation studies of AMV wind vectors derived from a GMS and from a cluster of low-earth-orbiting (LEO) small satellites (e.g., CubeSats). The results of two separate simulation studies are very encouraging and show that a ±2 m/s wind speed precision is attainable, which would satisfy WMO requirements. A GMS observing system in particular, which can be implemented now, would enable significant progress in the study of atmospheric dynamics. Copyright 2017 California Institute of Technology. Government sponsorship acknowledged

Humidity sensing behaviour of polyaniline/magnesium chromate

Indian Academy of Sciences (India)

The decrease in electrical resistance was observed when the polymer composites were exposed to the broad range of relative humidity (ranging between 20 and 95% RH). This decrease is due to increase in surface electrical conductivity resulting from moisture absorption and due to capillary condensation of water causing ...

Optical fiber relative humidity sensor based on a FBG with a di-ureasil coating.

Science.gov (United States)

Correia, Sandra F H; Antunes, Paulo; Pecoraro, Edison; Lima, Patrícia P; Varum, Humberto; Carlos, Luis D; Ferreira, Rute A S; André, Paulo S

2012-01-01

In this work we proposed a relative humidity (RH) sensor based on a Bragg grating written in an optical fiber, associated with a coating of organo-silica hybrid material prepared by the sol-gel method. The organo-silica-based coating has a strong adhesion to the optical fiber and its expansion is reversibly affected by the change in the RH values (15.0-95.0%) of the surrounding environment, allowing an increased sensitivity (22.2 pm/%RH) and durability due to the presence of a siliceous-based inorganic component. The developed sensor was tested in a real structure health monitoring essay, in which the RH inside two concrete blocks with different porosity values was measured over 1 year. The results demonstrated the potential of the proposed optical sensor in the monitoring of civil engineering structures.

Reproductive success of Horned Lark and McCown's Longspur in relation to wind energy infrastructure

Science.gov (United States)

Mahoney, Anika; Chalfoun, Anna D.

2016-01-01

Wind energy is a rapidly expanding industry with potential indirect effects to wildlife populations that are largely unexplored. In 2011 and 2012, we monitored 211 nests of 2 grassland songbirds, Horned Lark (Eremophila alpestris) and McCown's Longspur (Rhynchophanes mccownii), at 3 wind farms and 2 undeveloped reference sites in Wyoming, USA. We evaluated several indices of reproductive investment and success: clutch size, size-adjusted nestling mass, daily nest survival rate, and number of fledglings. We compared reproductive success between wind farms and undeveloped sites and modeled reproductive success within wind farms as a function of wind energy infrastructure and habitat. Size-adjusted nestling mass of Horned Lark was weakly negatively related to turbine density. In 2011, nest survival of Horned Lark decreased 55% as turbine density increased from 10 to 39 within 2 km of the nest. In 2012, however, nest survival of Horned Lark was best predicted by the combination of vegetation height, distance to shrub edge, and turbine density, with survival increasing weakly with increasing vegetation height. McCown's Longspur nest survival was weakly positively related to vegetation density at the nest site when considered with the amount of grassland habitat in the neighborhood and turbine density within 1 km of the nest. Habitat and distance to infrastructure did not explain clutch size or number of fledglings for either species, or size-adjusted nestling mass for McCown's Longspur. Our results suggest that the influence of wind energy infrastructure varies temporally and by species, even among species using similar habitats. Turbine density was repeatedly the most informative measure of wind energy development. Turbine density could influence wildlife responses to wind energy production and may become increasingly important to consider as development continues in areas with high-quality wind resources.

MoS{sub 2}-modified ZnO quantum dots nanocomposite: Synthesis and ultrafast humidity response

Energy Technology Data Exchange (ETDEWEB)

Ze, Lu [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Yueqiu, Gong, E-mail: yqgong@xtu.edu.cn [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Xujun, Li; Yong, Zhang [School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105 (China)

2017-03-31

Highlights: • MoS{sub 2}@ZnO QDs composite structure was synthesized by two-steps methods. • Ultrafast humidity sensing response is achieved by MoS{sub 2}@ZnO QDs humidity sensor. • Sensor performs excellent cycle stability from 11% to 95% RH. • Humidity sensor could detect wide humidity range (11–95%). - Abstract: In this work, ZnO quantum dots (QDs), layered MoS{sub 2} and MoS{sub 2}-modified ZnO QDs (MoS{sub 2}@ZnO QDs) nanocomposite were synthesized and then applied as humidity sensor. The crystal structure, morphology and element distribution of ZnO QDs, MoS{sub 2} and MoS{sub 2}@ZnO QDs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectrometry, respectively. The humidity sensing characteristics of the MoS{sub 2} and MoS{sub 2}@ZnO QDs against various relative humidity were measured at room temperature. The results show that the MoS{sub 2}@ZnO QDs sensor exhibits high sensitivity with an impedance variation of three or four orders of magnitude to relative humidity range of 11–95% and it exhibits a short response-recovery time (1 s for adsorption and 20 s for desorption) and excellent repeatability. The mechanisms of the excellent performance for humidity sensing of MoS{sub 2}@ZnO QDs sensor were discussed based on its impedance properties. Our work could offer guidelines to design higher performance especially ultrafast humidity response sensor utilizing the nanocomposite structure with two dimensional material and QDs.

Kinetics of moisture-induced hydrolysis in powder blends stored at and below the deliquescence relative humidity: investigation of sucrose-citric acid mixtures.

Science.gov (United States)

Kwok, Kaho; Mauer, Lisa J; Taylor, Lynne S

2010-11-24

Previous studies have shown that deliquescent organic compounds frequently exhibit chemical instability when stored in environmental conditions above their deliquescence relative humidity (RH). The goal of the current study was to investigate the effect of atmospheric moisture on the long-term chemical stability of crystalline sucrose-citric acid mixtures following storage at RHs at and below the mutual deliquescence relative humidity (MDRH). Interestingly, it was found that sucrose hydrolysis can occur below the MDRH of 64% and was observed for samples stored at 54% RH. However, hydrolysis was not seen for samples stored at 33 or 43% RH. The rate of sucrose hydrolysis could be modeled by taking into account the rate and extent of moisture uptake, which in turn was dependent on the composition of the powder and the storage RH. A reaction mechanism initiated by capillary condensation and involving additional deliquescence lowering by the degradation products formed as a result of sucrose hydrolysis (glucose and fructose) was proposed.

The Effect of Venue and Wind on the Distance of a Hammer Throw

Science.gov (United States)

Hunter, Iain

2005-01-01

In track and field, gravity and air resistance act on the hammer after it has been released. Both of these forces depend on altitude and latitude. In addition, air resistance also depends on wind, temperature, humidity, and barometric pressure. Often, air resistance and varying gravity throughout the earth are not considered when throwing…

Health symptoms in relation to temperature, humidity, and self-reported perceptions of climate in New York City residential environments

Science.gov (United States)

Quinn, Ashlinn; Shaman, Jeffrey

2017-07-01

Little monitoring has been conducted of temperature and humidity inside homes despite the fact that these conditions may be relevant to health outcomes. Previous studies have observed associations between self-reported perceptions of the indoor environment and health. Here, we investigate associations between measured temperature and humidity, perceptions of indoor environmental conditions, and health symptoms in a sample of New York City apartments. We measured temperature and humidity in 40 New York City apartments during summer and winter seasons and collected survey data from the households' residents. Health outcomes of interest were (1) sleep quality, (2) symptoms of heat illness (summer season), and (3) symptoms of respiratory viral infection (winter season). Using mixed-effects logistic regression models, we investigated associations between the perceptions, symptoms, and measured conditions in each season. Perceptions of indoor temperature were significantly associated with measured temperature in both the summer and the winter, with a stronger association in the summer season. Sleep quality was inversely related to measured and perceived indoor temperature in the summer season only. Heat illness symptoms were associated with perceived, but not measured, temperature in the summer season. We did not find an association between any measured or perceived condition and cases of respiratory infection in the winter season. Although limited in size, the results of this study reveal that indoor temperature may impact sleep quality, and that thermal perceptions of the indoor environment may indicate vulnerability to heat illness. These are both important avenues for further investigation.

The relative impact of photoionizing radiation and stellar winds on different environments

Science.gov (United States)

Haid, S.; Walch, S.; Seifried, D.; Wünsch, R.; Dinnbier, F.; Naab, T.

2018-05-01

Photoionizing radiation and stellar winds from massive stars deposit energy and momentum into the interstellar medium (ISM). They might disperse the local ISM, change its turbulent multi-phase structure, and even regulate star formation. Ionizing radiation dominates the massive stars' energy output, but the relative effect of winds might change with stellar mass and the properties of the ambient ISM. We present simulations of the interaction of stellar winds and ionizing radiation of 12, 23, and 60 M⊙ stars within a cold neutral (CNM, n0 = 100 cm-3), warm neutral (WNM, n0 = 1, 10 cm-3) or warm ionized (WIM, n0 = 0.1 cm-3) medium. The FLASH simulations adopt the novel tree-based radiation transfer algorithm TREERAY. With the On-the-Spot approximation and a temperature-dependent recombination coefficient, it is coupled to a chemical network with radiative heating and cooling. In the homogeneous CNM, the total momentum injection ranges from 1.6× 104 to 4× 105 M⊙ km s-1 and is always dominated by the expansion of the ionized HII region. In the WIM, stellar winds dominate (2× 102 to 5× 103 M⊙ km s-1), while the input from radiation is small (˜ 102 M⊙ km s-1). The WNM (n0 = 1 cm-3) is a transition regime. Energetically, stellar winds couple more efficiently to the ISM (˜ 0.1 percent of wind luminosity) than radiation (< 0.001 percent of ionizing luminosity). For estimating the impact of massive stars, the strongly mass-dependent ratios of wind to ionizing luminosity and the properties of the ambient medium have to be considered.

Quality and Control of Water Vapor Winds

Science.gov (United States)

Jedlovec, Gary J.; Atkinson, Robert J.

1996-01-01

Water vapor imagery from the geostationary satellites such as GOES, Meteosat, and GMS provides synoptic views of dynamical events on a continual basis. Because the imagery represents a non-linear combination of mid- and upper-tropospheric thermodynamic parameters (three-dimensional variations in temperature and humidity), video loops of these image products provide enlightening views of regional flow fields, the movement of tropical and extratropical storm systems, the transfer of moisture between hemispheres and from the tropics to the mid- latitudes, and the dominance of high pressure systems over particular regions of the Earth. Despite the obvious larger scale features, the water vapor imagery contains significant image variability down to the single 8 km GOES pixel. These features can be quantitatively identified and tracked from one time to the next using various image processing techniques. Merrill et al. (1991), Hayden and Schmidt (1992), and Laurent (1993) have documented the operational procedures and capabilities of NOAA and ESOC to produce cloud and water vapor winds. These techniques employ standard correlation and template matching approaches to wind tracking and use qualitative and quantitative procedures to eliminate bad wind vectors from the wind data set. Techniques have also been developed to improve the quality of the operational winds though robust editing procedures (Hayden and Veldon 1991). These quality and control approaches have limitations, are often subjective, and constrain wind variability to be consistent with model derived wind fields. This paper describes research focused on the refinement of objective quality and control parameters for water vapor wind vector data sets. New quality and control measures are developed and employed to provide a more robust wind data set for climate analysis, data assimilation studies, as well as operational weather forecasting. The parameters are applicable to cloud-tracked winds as well with minor