Effect of relative humidity on the lifting of charged sand grains in an electric field

The effect of acidity and relative humidity on bulk isoprene aerosol parameters has been investigated in several studies; however, few measurements have been conducted on individual aerosol compounds. The focus of this study has been the examination of the effect of acidity and relative humidity on secondary organic aerosol (SOA) chemical composition from isoprene photooxidation in the presence of nitrogen oxide (NOx). A detailed characterization of SOA at the molecular level was also investigated. Experiments were conducted in a 14.5 m3 smog chamber operated in flow mode. Based on a detailed analysis of mass spectra obtained from gas chromatography–mass spectrometry of silylated derivatives in electron impact and chemical ionization modes, ultra-high performance liquid chromatography/electrospray ionization/time-of-flight high-resolution mass spectrometry, and collision-induced dissociation in the negative ionization modes, we characterized not only typical isoprene products but also new oxygenated compounds. A series of nitroxy-organosulfates (NOSs) were tentatively identified on the basis of high-resolution mass spectra. Under acidic conditions, the major identified compounds include 2-methyltetrols (2MT), 2-methylglyceric acid (2mGA), and 2MT-OS. Other products identified include epoxydiols, mono- and dicarboxylic acids, other organic sulfates, and nitroxy- and nitrosoxy-OS. The contribution of SOA products from isoprene oxidation to PM2.5 was investigated by analyzing ambient aerosol collected at rural sites in Poland. Methyltetrols, 2mGA, and several organosulfates and nitroxy-OS were detected in both the field and laboratory samples. The influence of relative humidity on SOA formation was modest in non-acidic-seed experiments and stronger under acidic seed aerosol. Total secondary organic carbon decreased with increasing relative humidity under both acidic and non-acidic conditions. While the yields of some of the specific organic compounds decreased with increasing relative humidity, others varied in an indeterminate manner from changes in the relative humidity.

With increasing walnut production in California, walnuts are stored for longer times. It is increasingly important to optimize storage conditions, wherever possible, to reduce quality degradation. We examined the effects of temperature (5, 15, and 25 °C) and relative humidity (20%, 40%, and 60% in year 1 and 40%, 60%, and 80% in year 2) on the rate of quality degradation of four walnut varieties. The relationship between water activity and moisture content was investigated for each variety. In addition, the effects of harvest timing (early vs. late) and storage as shelled or in-shell product were investigated. Later harvested walnuts had darker kernel color ( P < 0.001), and walnuts stored as kernels (shelled) had higher rates of peroxide formation and free fatty acid development than walnuts stored in-shell. Temperature had a significant effect on quality with faster degradation at higher temperatures. There was a significant interaction between temperature and relative humidity effects on quality. The effects of relative humidity were often not significant at storage temperatures of 5 °C but were apparent at 15 °C and at 25 °C. Managing relative humidity during walnut storage is difficult under typical commercial storage conditions; however, when low temperature storage is used, quality is preserved even when relative humidity is not controlled, although storage at 80% relative humidity should be avoided. To reduce the rate of color darkening and rancidity development during commercial storage, operators should emphasize storage at lower temperatures, at least below 15 °C.

Effect of relative humidity on the enhancement of the triboelectrification efficiency utilizing water bridges between triboelectric materials

Torsional fretting wear behaviour of 7075 aluminium alloy in various relative humidity environments

SummaryTo investigate the effect of temperature and relative humidity (RH) on the absorption kinetics of self‐activated and moisture‐activated O2 scavengers for packaged food, kinetic parameters of each O2 scavenger were evaluated at 43%, 75% or 100% RH and at 10, 25 and 40 °C respectively. Absorption kinetics was well described by a first‐order reaction with an Arrhenius type behaviour. For moisture‐activated O2 scavengers, a proper high RH was needed to ensure a high O2 absorption capacity, as average O2 absorption capacity was 3.82 mL at 43% RH and 43.40 mL at 75% RH. When the temperature increased, O2 absorption rate constant ascended from 10 °C to 40 °C on an average of 0.153 and 0.306 h−1 in moisture‐activated and self‐activated O2 scavengers respectively. We could take the effect of temperature and RH into account when we chose different types of iron‐based O2 scavengers for packaged food.

Four air temperature levels of 23, 25, 27 and 29C, three humidity levels of 85, 90 and 95%R.H. and two photosynthetic photon flux (PPF) levels of 30 and 50 jumol m-2 s-1 were provided to investigate the effects of air temperature, relative humidity and light intensity on the evapotranspiration rate (EVTR) of watermelon grafted seedlings. EVTR of grafted seedlings increased with increasing air temperature and the passage of time after grafting. Also EVTR increased with decreasing relative humidity. EVTR of grafted seedlings at dark period reduced by half of those at photoperiod. Effect of relative humidity on the EVTR of grafted seedlings was distinctly shown at relatively high PPF. As the vapor pressure deficit decreased, the graft-taking of grafted seedlings increased. Under the high humidity more than 90%, EVTR was gradually increased with days after grafting and thus the scion and rootstock were also smoothly joined together. It is required to control optimally the environment for decreasing the vapor pressure deficit and preventing the wilting of grafted seedlings under artificial lighting during first 2–3 days after grafting. And then it is suggested to lower the relative humidity and raise the PPF by steps for the robust joining of grafted seedlings.

Objectives: This study was performed to examine bioaerosols in indoor air in public restrooms, as well as to assess the effects of air temperature and relative humidity on bioaerosol levels. Methods: A cross-sectional survey was performed in ten male and ten female restrooms. An air sampler (Anderson type) was used for sampling total suspended bacteria (TSB), Gram-negative bacteria (GNB), Gram-positive bacteria (GPB), opportunistic bacteria (OP), Staphylococcus spp., and total suspended fungi (TSF). Results: The levels of TSB were <TEX>$10-10^2CFU/m^3$</TEX> and TSF <TEX>$10-10^2CFU/m^3$</TEX>, respectively. The GNB level was <TEX>$0-10CFU/m^3$</TEX>, and GPB and OP levels were <TEX>$10-10^2CFU/m^3$</TEX>. Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) were detected in 90% of the restrooms. The GPB level was higher in the female restrooms than in the male restrooms (p < 0.05). TSB, GNB, and TSF showed higher levels in restrooms in buildings over 30 years old (p < 0.01). The main effect of air temperature or relative humidity and interaction effect of the two factors on the TSB level were significant (p < 0.05), while the effect of relative humidity on the TSF level was significant (p < 0.001). Conclusions: These results indicate that there is a wide variation in the bioaerosol levels among different restrooms. The observed differences in bioaerosol levels reflect different building histories. The effects of air temperature and/or relative humidity reveal that bioaerosol levels may vary according to season or time of day. Future research is needed to further characterize the relation between the bioaerosol levels and surface contamination in restrooms.

The energy used by information technology (IT) equipment and the supporting data center equipment keeps rising as data center proliferation continues unabated. In order to contain the rising computing costs, data center administrators are resorting to cost cutting measures such as not tightly controlling the temperature and humidity levels and in many cases installing air side economizers with the associated risk of introducing particulate and gaseous contaminations into their data centers. The ASHRAE TC9.9 subcommittee, on Mission Critical Facilities, Data Centers, Technology Spaces, and Electronic Equipment, has accommodated the data center administrators by allowing short period excursions outside the recommended temperature-humidity range, into allowable classes A1-A3. Under worst case conditions, the ASHRAE A3 envelope allows electronic equipment to operate at temperature and humidity as high as 24°C and 85% relative humidity for short, but undefined periods of time. This paper addresses the IT equipment reliability issues arising from operation in high humidity and high temperature conditions, with particular attention paid to the question of whether it is possible to determine the all-encompassing x-factors that can capture the effects of temperature and relative humidity on equipment reliability. The role of particulate and gaseous contamination and the aggravating effects of high temperature and high relative humidity will be presented and discussed. A method to determine the temperature and humidity x-factors, based on testing in experimental data centers located in polluted geographies, will be proposed.

Effect of different relative humidities (room, 10%, 46% and 97% R. H.) on the oil extracted from cottonseed stored for one year was studied. The oil extracted from recent non-stored cottonseed was used as a control. Moisture content and oil content in the seed and acid value, peroxide value and percentage gossypol in the oil were determined. The results obtained for the oil extracted from the seed stored under (room, 10% and 46% R. H.) showed a slight difference with the results obtained for the oil extracted from the non-stored conttonseed, while the results of the oil extracted from the seed stored under 97% R. H. showed a considerable difference. Fatty acids composition and unsaturated: saturated fatty acids ratio (U:S) were also evaluated in previous oils. Unsaturated fatty acids were decreased by storage. Accordingly U:S was also decreased. Effect of relative humidity during storage of the cottonseeds on refining and bleaching of the oil was also investigated. The oil of the cottonseed stored under (room, 10% and 46% R. H.) was satisfactorily refined and bleached, givining oils with good colour. While the oil of the cottonseed stored under 97% R. H. could not be satisfactorily refined and bleached. The oil was very dark in colour and did not response to refining and bleaching.

The effect of relative humidity on both air permeability and rate of carbonation is investigated. Descriptive models, based on data from an accelerated carbonation test, were developed to quantify the effects of the relative humidity and the air permeability on the rate of carbonation. The relationships between the rate of carbonation and physical properties, such as the permeation properties and compressive strength were established. It was found that the permeation measurements should only be used to estimate the likely rate of carbonation when the relative humidity of the concrete specimen is known.

The effect of relative humidity on activated carbon adsorption of trichloroethylene (TCE) was determined. Five levels of relative humidity were tested for each of four TCE influent concentrations. The effect of humidity was greatest at the lowest TCE influent concentration (300 mg/m3) and highest relative humidity involved (85%). Under those conditions the amount of TCE adsorbed was only 9% of the amount adsorbed at the same challenge concentrations and lowest relative humidity (5%). The effect of humidity was negligible at the highest TCE concentrations (1000 and 1300 mg/m3) and moderate level of relative humidity (25%). Under all other conditions tested the effect was intermediate to these extremes. Differences in TCE breakthrough curves caused by the presence of water vapor are presented and discussed. Data sets (grouped by relative humidity) fit the Dubinin - Polanyi equation equally well.

The effect of relative humidity (RH) of air on the mechanical properties of roasted turkey breast was studied using a rheological model. The raw turkey breast with a moisture content of ca. 75%, protein content of ca. 24% and fat content of ca. 1% was roasted in a convection steam oven at 180C and five RH levels (0, 20, 50, 70 and 90%). The elastic modulus decreased, whereas the flow consistency index and the flow limit increased with an increase in RH from 0 to 70%. Significant differences were observed in elastic modulus between RH levels of 0 and 20% versus 50, 70 and 90%. As regard the flow consistency index and the flow limit, significant differences were observed between 0 versus 50 and 70% RH levels. No significant differences in those values were reported at RH exceeding 50%. The flow consistency index was independent of RH of air level.Practical ApplicationsThe proposed method can be used to determine the effect of treatment parameters on the rheological properties of the analyzed product, and to assess its final quality. The presented mathematical model allows to evaluate the rheological properties of turkey breast meat roasted in a convection steam oven independently of the type of mechanical tests used to determine those values. The obtained results support the selection of roasting parameters (relative humidity) aimed at yielding a product with the desired rheological properties.

Spectral distribution changes in atmosphere have a significant impact on performance behaviour of photovoltaic system. Various atmospheric constituents absorb and reflect irradiance at different wavelengths, which results in changes in atmospheric spectrum. The performance of photovoltaic modules is influenced by spectra distribution of the respective site even if the irradiance level and the operating temperature remain unchanged. In this study, the effect of Relative Humidity (RH) and Ambient temperature is reported as a vital function for spectra distribution. Also, the mutual effect of POA (Plan of array) and Precipitable water content (Pwat) on PR (Performance ratio) gives a strong comprehensive correlation for predictive module performance analysis for the respective location.Spectral distribution changes in atmosphere have a significant impact on performance behaviour of photovoltaic system. Various atmospheric constituents absorb and reflect irradiance at different wavelengths, which results in changes in atmospheric spectrum. The performance of photovoltaic modules is influenced by spectra distribution of the respective site even if the irradiance level and the operating temperature remain unchanged. In this study, the effect of Relative Humidity (RH) and Ambient temperature is reported as a vital function for spectra distribution. Also, the mutual effect of POA (Plan of array) and Precipitable water content (Pwat) on PR (Performance ratio) gives a strong comprehensive correlation for predictive module performance analysis for the respective location.

The effects of air temperature, relative and specific humidity, wind speed, solar shortwave radiation, thermal longwave radiation, and rain on the performance of participants in the annual Stockholm Marathon from 1980 to 2008 were analysed statistically. The objective was to validate and extend previous studies by including data on finishing times of slower male and female runners and on the percentage of non-finishers. Due to decadal trends in the finishing time not related to weather, the finishing time anomaly (FTA) was calculated as the deviation of the annual finishing time from the linear trend of the finishing time. In all categories of runners, the single weather parameter with highest correlation with the FTA was the air temperature (correlation coefficient r = 0.66-0.73, with the highest values for slowest runners). Also, the solar shortwave radiation (r = 0.41-0.71), air relative humidity (r = -0.57 to -0.44) and, for male runners, the occurrence of rain (r = -0.51 to -0.42) reached a statistically significant correlation with the FTA, but the effects of the relative humidity and rain only arose from their negative correlation with the air temperature. The percentage of non-finishers (PNF) was significantly affected by the air temperature and specific humidity (r = 0.72 for multiple regression), which is a new result. Compared to faster runners, the results of slower runners were more affected by unfavourable weather conditions; this was previously known for runners with finishing times of 2.1-3 h, and now extended to finishing times of 4.7 h. Effects of warm weather were less evident for female than male runners, which was probably partly due to female runners' larger ratio of surface area to body mass and slower running speed.

Effect of Relative Humidity on the Mechanical Properties of Micro and Nanocomposites of Polyvinyl Alcohol