Drop In Relative Humidity Research Articles

Development of craquelure patterns in paintings on canvas

Canvas paintings are layered structures composed of canvas support sized with animal glue, a preparatory layer of the ground, and paint and varnish layers on the top. Preventing or limiting humidity-induced stresses in these structures requires an understanding of the relevant processes and risks. A three-dimensional model of a canvas painting was used to analyse stresses and crack development in the two-layer structure comprised of a glue-sized canvas on a wooden stretcher with a layer of stiff chalk-glue ground representing a pictorial layer in historic canvas paintings. The model was subjected to a large relative humidity fall which induced shrinkage of the glue-sized canvas. The modelling revealed that when a stretcher with flexible wooden bars is considered, high tensile stresses arise in the ground layer at the corners of the painting, and cracks are formed in these areas in the direction perpendicular to the painting’s diagonal. Ratios of critical distances between cracks to the ground layer thickness for which stresses in the midpoints between the cracks dropped to below the level inducing fracture in the material were estimated for various magnitudes of the relative humidity drop and thicknesses of the ground layer. Increasing ground layer thickness limits the hygric response of the sized canvas and makes the paintings less vulnerable to humidity variations. The ratio of stress along the diagonal calculated for painting with one crack to the solution without cracks was described by the double Lorentz function. A simple procedure of calculating stress variations along the diagonal—using the function—on a sequential addition of cracks was developed. Cracks in central parts of canvas painting were found to be induced by permanent cumulative drying shrinkage of the oil-based paints and grounds due to the evolution of the molecular composition of the oil binder. The outcome of the modelling indicated that the risk of cracking of the pictorial layers in canvas paintings due to drops in ambient relative humidity was small.

Hydroclimate of the Messinian Salinity Crisis constrained from paleo-water triple oxygen, hydrogen, and strontium isotopes

Giant evaporite deposits formed during the Messinian Salinity Crisis (MSC) in the Mediterranean Sea during the upper Miocene. The primary cause is a restricted Atlantic-Mediterranean connection, but the detailed hydroclimate evolution of this event is still a matter of debate. Here we reconstruct the triple oxygen and hydrogen isotopic composition of paleo brines from structurally bonded water in Messinian gypsum from Cyprus. A two-stage evaporation model is constructed to best approximate the hydrological conditions at which Messinian gypsum formed in marginal basins of the Mediterranean Sea. Subsequently, hydroclimatic parameters like paleo relative humidity (RH) are modelled using an iterative curve fitting isotope model approach. The results of our limited dataset reveal a slightly lower RH during the third compared to the second stage of the MSC. This apparent drop in RH is consistent with previous observations from the literature.Besides absolute values of RH, our model allows reconstructing the triple oxygen and hydrogen isotopic composition of the open Mediterranean Sea. This provides an estimate for the proportions of continental water vs. Atlantic seawater flowing into the basin, serving as a proxy for the size of the strait of Gibraltar. The model implies a continental water fraction of around 75–81 % both for the second and third stage of the MSC. In addition, we determined the 87Sr/86Sr of our samples to: i) confirm their stratigraphy; and ii) estimate the relative proportion of continental water vs. Atlantic seawater entering the Mediterranean using Sr mass balance calculations. The combined oxygen and Sr isotope records indicate a persistent connection to the Atlantic supporting the hypothesis that the striking drop in 87Sr/86Sr at the beginning of MSC stage 3 is mainly related to an increased contribution of continental water with low 87Sr/86Sr and high Sr concentrations from the Paratethys. Our results show that the combination of triple oxygen, hydrogen, and Sr isotope data provides a powerful tool to disentangle paleo-hydroclimate even in such complicated hydrological settings as the Mediterranean Sea during the MSC.

Dehydration stress and Mayaro virus vector competence in Aedes aegypti.

Relative humidity (RH) is an environmental variable that affects mosquito physiology and can impact pathogen transmission. Low RH can induce dehydration in mosquitoes, leading to alterations in physiological and behavioral responses such as blood-feeding and host-seeking behavior. We evaluated the effects of a temporal drop in RH (RH shock) on mortality and Mayaro virus vector competence in Ae. aegypti. While dehydration induced by humidity shock did not impact virus infection, we detected a significant effect of dehydration on mosquito mortality and blood-feeding frequency, which could significantly impact transmission dynamics.

Winter heat waves characteristics associated with downslope windstorm in south Brazil

AbstractThe air temperature anomaly was analysed in 16 consecutive winters from 2004 to 2019 in southern Brazil using reanalysis data and hourly atmospheric observations. In this study, 13 heat wave (HW) episodes were identified using the percentile methodology. All identified episodes are associated with the occurrence of a downslope windstorm known as Vento Norte (VNOR; Portuguese for ‘North Wind’). The VNOR is characterized by a sharp increase in air temperature combined with constant, strong, gusty winds from the north and a drop in relative humidity. The average duration was about 5 days for HW and 18 h for VNOR being than in 59.5% of the HW hours, the VNOR windstorm was also detected. The main atmospheric variables were compared during the periods of winter, HW and the VNOR windstorm. The analysis showed that HW alters local weather and climate conditions, with the more pronounced features associated with the VNOR flow. A more detailed investigation comparing the atmospheric variables collected north and south of an abrupt change in terrain altitude (400 m) revealed that the main cause of the amplification of the atmospheric variable anomalies in the centre of the state of Rio Grande do Sul was the simultaneous occurrence of HW and VNOR.

Numerical modelling of mechanical degradation of canvas paintings under desiccation

Mechanical damage in oil paintings on canvas show up as cracks and loss of original paint. Several parameters can contribute to this type of degradation. These paintings have a complex layered structure, typically composed of minimum four or more hygroscopic materials, each of which has different (non-linear) material properties and geometrical complexities. The mechanical degradation of canvas paintings occurs because each of these materials have diverse responses under fluctuating environmental conditions, especially temperature and relative humidity (RH). By examining the geometrical complexities and the non-linear material properties, this paper presents an investigation of three degradation phenomena under desiccation: (1) bulging formation around the corners, (2) crack formation in glue and ground layers, and (3) plastic deformation in the ground and oil paint layers.This on-going investigation provides further insights into the global and local stress distribution in typically constructed oil canvas paintings. This includes finite element method (FEM) and extended-FEM (XFEM) computer models at various scales, under desiccation from the initial RH of 90%, and 50–10%. The models consist of four to five different materials, namely lead white oil paint, red iron oxide oil paint, rabbit skin glue, linen canvas, and a spruce stretcher. The models were constructed using several combinations of materials to conduct parametric studies on the effects of glue shrinkage in paintings due to desiccation, and changing the mechanical properties of the ground layers. The relevant geometrical and mechanical properties with respect to the stress relaxation conditions are discussed in detail.The simulation results of the full-scale models show that the shrinkage of glue lowers the level of induced tension stresses in the paint layers in the central area of the painting due to the inward bowing of the stretcher. The inward deformation of the stretcher can be 4.5 times as large in a painting with a glue layer as in one without. This indicates the difficulty in forming cracks near the center of paintings purely by desiccation; however, in close-up cross-section model, cracks of 20 μm in length could still be observed in the ground exposed to an extreme RH change of 90% to 10%.The analysis of cross-section models with the full geometrical complexity for the corners showed that multiple cracks are likely to form in ground and paint layers in the corners when desiccated by 40%; RH 50–10%. Furthermore, in extreme cases with stiffer ground/paint such as zinc white, cracks can form from smaller drop in RH; RH 50% to 35%. Such cracks are form in the ground layers, and therefore, are not initially visible as they are positioned below the uncracked paint layer. This result can be the possible explanation for cracks in the ground, which are initially invisible with the naked eye, but can be revealed with X-radiographs.The results support the hypothesis that fluctuations in relative humidity can cause hidden cracks in the lower layers, which can eventually propagate further into the upper-lying paint layers of paintings. The cracks typically form when the desiccation reaches a 40% drop, but in cases of brittle materials the drop causing cracks can be lower. The actual RH drop causing cracks depends on the specific material composition.

Thermodynamic modelling of perchlorate/chloride and perchlorate/chlorate deliquescence at Mars-relevant temperatures

Perchlorate (ClO4−) salts were discovered on Mars and are known to absorb water vapor from the atmosphere and deliquesce into the aqueous phase. Other species such as chlorides (Cl−) and chlorates (ClO3−) were also identified; these species can affect the deliquescence of perchlorates. Here we generate phase diagrams of perchlorate/chloride and perchlorate/chlorate binary mixtures for K, Na, Mg and Ca in the temperature range 223–273 K. Using a new approach based on thermodynamic modelling of evaporation, we determined the deliquescence relative humidity (the minimum relative humidity at which a salt converts into a liquid by absorbing atmospheric water vapor) and the eutonic relative humidity (the minimum relative humidity at which two salts are in equilibrium with liquid) for binary salt mixtures. Our modelling results show that the deliquescence relative humidity values of all salt mixtures is always lower than that of each individual end-member salt at a fixed temperature, typically a few percent lower. The closer the eutonic is to one of the end-member, the smaller the decrease in relative humidity compared to the pure pole. Thus, only eutonics which are far from both poles exhibit a significant drop in relative humidity. Moreover, the eutonic relative humidity always increases with decreasing temperature, which does not favor liquids in the dry and cold Martian environment. Finally, the increased stability of water ice at the lowest temperatures always reduces or even eliminates the stability of liquids. Therefore, the favorable temperature and relative humidity conditions under which binary salt liquid mixtures exist are generally not significantly improved compared to single salts.

Investigation of June 2020 giant Saharan dust storm using remote sensing observations and model reanalysis

This paper investigates the characteristics and impact of a major Saharan dust storm during June 14th–19th 2020 on atmospheric radiative and thermodynamics properties over the Atlantic Ocean. The event witnessed the highest ever aerosol optical depth for June since 2002. The satellites and high-resolution model reanalysis products well captured the origin and spread of the dust storm. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measured total attenuated backscatter and aerosol subtype profiles, lower angstrom exponent values (~ 0.12) from Modern-Era Retrospective Analysis for Research and Application—version 2 (MERRA-2) and higher aerosol index value from Ozone monitoring instrument (> 4) tracked the presence of elevated dust. It was found that the dust AOD was as much as 250–300% higher than their climatology resulting in an atmospheric radiative forcing ~ 200% larger. As a result, elevated warming (8–16%) was observed, followed by a drop in relative humidity (2–4%) in the atmospheric column, as evidenced by both in-situ and satellite measurements. Quantifications such as these for extreme dust events provide significant insights that may help in understanding their climate effects, including improvements to dust simulations using chemistry-climate models.

Mount Everest's photogenic weather during the post‐monsoon

Mount Everest's photogenic weather during the post‐monsoon

Experimental Investigation and Neural network based parametric prediction in a multistage reciprocating humidifier

Cooling of the buildings is very much mandatory in summer and to meet this, considerable energy will be spent for cooling purpose across the world. Present work focuses on the multistage evaporative cooling pads where four different packing are used to analyze the different humidification output parameters. Cam shaft which is powered by the motor gives reciprocating motion to the cooling pads which is made to dip inside the stagnant water. Input operating parameters such as air velocity, cam shaft speed and the number of cooling pads are varied and the output parameters like pressure drop, cooling effect, coefficient of performance, relative humidity drop and energy consumption rate are determined. Results indicated that, there is an increase in COP, pressure drop and the energy consumption rate with the rise in the air velocity. Artificial neural network has been used for predicting the performance parameters of the experimental results. 3-15-4 structured MLP based network is considered and is trained by using trainscg, trainlm and using trainbr networks. Results indicated a good prediction capability of ANN techniques with MRE of test data lying below 12%. Trainbr outperformed the other two networks as the correlation coefficient was much higher and MRE was lower for both training as well as test data.

Energy density and fracture parameters of coated Scots pine

An attempt was made to investigate the Michalski’s proven fluctuation theory through the use of the fracture characteristic and the energy density – dynamic surface value – of Scots pine coated with Renaissance wax, paraloid, and tar. The slices were acclimatized in a climate chamber with an abrupt drop of relative humidity from 80% to 30% while being monitored by acoustic emission. During this period, macro-cracks were formed in the slices coated with the paraloid and tar while those coated with Renaissance wax were remained undamaged. Moreover, fracture tests along with the Finite Element Analysis (FEA) were utilized to calculate the critical values of the stress intensity factor. Furthermore, the alternative correlation, accounting for the effect of different specimens’ length, introduced into the ASTM E833 standard resulting in agreeable values of fracture toughness as compared with the experimental data. Finally, the relation between the crack propagation and the fracture toughness with the ductile (load increase) and the brittle (load decrease) portions of the dynamic surface value (DSV) was investigated. It was observed that the impact of the latter portion in the crack propagation of the undamaged slices was more dominant, while the portion contributed almost the same in crack propagation of the damaged slices.

Experimental investigation of transient thermal comfort for the indoor vegetation

ABSTRACT Present work focuses on sustainable energy-based technique for achieving the required thermal comfort inside a greenhouse unit. A region of definite volume is built, and the plants are placed inside it. Evaporative cooling setup consists of cooling pads, water spray unit and a blower are designed to regulate the ventilation inside the space. Experiments are conducted for a fixed peak time and changing the flow rate of air. Results indicated that the maximum temperature drop, and relative humidity drop values are observed to be 7.7°C and 22%. It is seen that optimum performance could be obtained for an airflow rate of 12 m/s and the corresponding Coefficient of Performance (COP), evaporation rate and cooling efficiency values are 2.4787, 0.1181 g/s and 60.05%, respectively.

Influence of zeolite addition on mechanical performance and shrinkage of high strength Engineered Cementitious Composites

In this study, calcined zeolite particles were used as internal curing agent to replace cement and quartz sand simultaneously in Ordinary Portland Cement(OPC) based Engineered Cementitious Composites(ECC) material. The influence of the zeolite-cement replacement on the mechanical performance and the shrinkage of the materials were experimentally investigated. ECC specimens with water-binder ratio of 0.2 and zeolite content of 192 kg/m3 were prepared, and the zeolite-cement replacements were controlled as 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%. Compression test, uniaxial tension, shrinkage and relative humidity test were conducted on the specimens. The test results show that, with the increase of the zeolite-cement replacement, the strength of the material first increases and then decreases, and the crack width control ability during tension process is improved. The autogenous shrinkage control ability and the relative humidity of the material are also improved, while the zeolite-cement replacement has little influence on the drying shrinkage and the relative humidity drop caused by environmental drying.

Numerical modelling of climate-induced fracture and deformation in wood: Application to historical museum objects

Damage in oak wood museum objects under indoor climate variations (relative humidity, temperature) is studied using a thermo-hygro-mechanical model. The model incorporates the effects of moisture sorption hysteresis and discrete cracking, and is implemented within a finite element framework using a staggered update procedure. Sorption experiments were performed in order to calibrate the moisture sorption hysteresis model. The basic features of the coupled formulation are stepwisely demonstrated by solving the response of a basic oak wood specimen under a sequence of thermo-hygro-mechanical loading conditions of increasing complexity. These simulations show that the deformation and fracture generated by thermal variations representative of indoor museum conditions are minor compared to the contributions caused by relative humidity variations. Subsequently, the hygro-mechanical response of an oak wood cabinet door panel is analysed under a drop in relative humidity from 60% to 20%, and the results are compared to those obtained by experiments. The numerical and experimental results are in good agreement, and indicate that at the connection between the cleated end and the vertical boards the restrained hygric shrinkage is maximal, which stimulates local crack development. The susceptibility to fracture only becomes activated after the oak wood has reached a certain age, as the effect of aging induces a decrease of the oak wood tensile strength perpendicular to the grain direction with time. Further, when the initial moisture content lies on the desorption boundary curve, the amount of fracture generated is larger compared to when it lies on the adsorption boundary curve. Also, fracture only nucleates after a specific drop in relative humidity, whereby the crack growth under a continuous decrease in relative humidity initially develops relatively fast, but at a certain stage decreases substantially and becomes (almost) zero when reaching a fully developed failure crack. The location and orientation of this failure crack are in accordance with in situ observations on historical oak wood cabinets.

Modeling Temperature- and Humidity-Dependent Kinetics of Oxygen Reduction Reaction

Designing active catalysts for oxygen reduction reaction (ORR) is one of the major challenges for polymer electrolyte fuel cells. Density functional theory (DFT) calculations have made significant contributions on understanding ORR pathways, rate-limiting step and catalytic activity on various transition metal surfaces 1-5. However, all these theoretical studies are for reactions at room temperature in aqueous liquid electrolytes. The condition is significantly different from actual operation conditions of fuel cells [60 to 80 °C and 30 to 100 % relative humidity (RH)]. Although the DFT models reasonably explain experimental results obtained by the rotating disk electrode (RDE) at room temperature in aqueous liquid electrolytes, the reaction mechanism and catalytic activity at the operating conditions can be significantly different. Here, we examine effects of temperature and RH on the ORR by using a micro-kinetic model. The examination indicates that both the rate-limiting step and material-dependence of the catalytic activity are strongly influenced by both temperature and RH.The theoretical analyses were carried out by extending a micro-kinetic model proposed by Hansen et al5 to higher temperature and lower RH conditions. For the extension, following assumptions were adopted. Free energies for reaction intermediates (adsorbed O, OH and HO2) are independent of temperature and relative humidity (RH) and fixed at the values in the original model.An additional reaction barrier due to the solvent reorganization, which was introduced to explain the experimentally observed prefactor in the original model, is entirely attributed to be enthalpic. The assumption (1) can be partially validated by relatively small entropies of the adsorbed species comparing with gaseous species. Because the assumption (2) is not verified, we also carried out the same simulation assuming that the solvent reorganization barrier is fully entropic [we define this assumption as (3)].Figures 1 (a) and (c) show the calculated ORR current density at 0.9V vs. reversible hydrogen electrode (RHE) under 1 atm O2 under the assumption (2) as a function of the binding energy of OH adsorbate vs. that of Pt (111). Figures 1 (b) and (d) show the calculated ORR current density in the same way as Figures 1 (a) and (c) under the assumption (3). In all conditions, in the right leg of the volcano-plot, where the OH binding energy is larger than the optimal point, the reaction is limited by the formation of the reaction intermediates. On the other hand, in the left leg of the volcano, the reaction is limited by the removal of the OH adsorbate. Regardless the type of the assumption [(2) or (3)], both the optimal catalytic activity and the optimal OH binding energy decrease with the rise in the temperature from 25 to 80 °C [see Figs. 1 (a) and (b)]. The low catalytic activity at high temperature is attributed to the drop in the reversible potential of ORR at high temperature. The shift in the optimal OH binding energy is attributed to the destabilization of OH adsorbate relative to the non-adsorbed species, which hold larger entropies than the adsorbates. The drop in RH enhances the optimal catalytic activity, while the opposite shift is observed for the optimal OH binding energy [see Figs. 1 (c) and (d)]. The both trends stem from the lowering of the water activity, which promotes the OH removal from the surface. All in all, our theoretical analyses indicate that the optimal OH binding energy strongly depends on both temperature and RH, indicating that the optimal catalyst at low temperature and in aqueous liquid electrolytes may not be optimal anymore at high temperature and low RH. Although our theoretical analyses strongly rely on non-verified assumptions (1)-(3) and the DFT model adopting the ice-like water,1 which is unlikely a proper model of the electrolyte at high temperature and low RH, the observation indicates the significance of more precise understanding of temperature-, RH- and material-dependence of ORR.In the presentation, we will present experimental data on temperature- and RH-dependent ORR activity and discuss the validity of the theoretical model. References J. K. Nørskov et al., J. Phys. Chem. B, 108, 17886 (2004).J. Greeley et al., Nat. Chem., 1, 552 (2009).J. X. Wang et al., J. Phs. Chem. A, 111, 12702 (2007).R. Jinnouch et al., Phys. Chem. Chem. Phys., 13, 21070 (2011).H. A. Hansen et al., J. Phys. Chem. C, 118, 6706 (2014). Figure 1

Widely sensitive optical humidity module by using acrylic resin and a position sensitivity detector

Humidity sensor module fabricated using acrylic resin and PSD (position sensitivity detector). In order to directly convert to electrical signal from output signal of optical humidity sensor system consisted of a light source, a gap, and an acrylic resin film coated on PSD. For the purpose of convert to 4–20 mA signal from current change according to the relative humidity (RH) integrated amplification of output current and 4–20 mA module by a 0.8 µm analog mixed CMOS process. Using the fabricated humidity sensor and Pt-100 accomplished one-bodied temperature-humidity sensor module and tested. The experimental results show that the sensitivity and linearity of sensor get better, while the thickness of the acrylic resin film is increased. The linearity of RH-current characteristics is good in the measuring range from 10 to 90% at 15 °C. The sensitivity of this sensor is 6.52–7.34μA/% RH. Furthermore, the current at PSD is measured with the rise and drop of RH, and the four times repetition is also recorded, which all demonstrate the good stability and repeatability of our proposed structure.

The role of spring dry zonal advection in summer drought onset over the US Great Plains

Abstract. This study addresses the role of the atmospheric moisture budget in determining the onset and development of summer droughts over the North American Great Plains (GP) using two state-of-the-art reanalysis datasets. We identified zonal moisture advection as the main cause of severe tropospheric drying during the extreme droughts in the southern GP in 2011 and northern GP in 2012. For both events, the eastward advection of anomalously dry and warm air in the free troposphere in spring set the stage for summer drought. This led to a sharp drop in relative humidity above the boundary layer, enhancing dry entrainment and suppressing deep convection. Further breakdown of the zonal advection into dynamic (caused by circulation anomalies) and thermodynamic (caused by moisture anomalies) contributions reveals dominance of thermodynamic advection in the tropospheric drying observed during the onset of both 2011 and 2012 droughts. The dependence of thermodynamic advection on the moisture gradient links springtime precipitation in the Rockies and southwestern US, the source region of the anomalous dry advection, to the GP summer precipitation (with correlations > 0.4 using gauge-based data). Identifying this previously overlooked precursor of the GP summer droughts improves our predictive understanding of drought onset mechanisms over the region.

Satellite and ground-based observation of pre-earthquake signals—a case study on the Central Italy region earthquakes

The complexity in earthquake occurrences has forced scientists to adopt an interdisciplinary approach for the development short-term forecasting model. In this manuscript, the authors have presented an interdisciplinary scheme involving pre-earthquake signals like geo-electrical measurements, relative humidity (RH) and outgoing longwave radiation (OLR). Prior to the occurrence of earthquakes, these parameters show exceptional deviation and indicate the nucleation of the earthquakes at the seismically active zones. Variations in the geo-electrical potential are observed prior to the occurrence of the earthquakes due to the physical and chemical interactions between hydrogen and Earth’s interior, which in turn facilitates the migration of the H+ ions through the interior of the earth. Also, this migration process weakens lithosphere, which produces non-synchronous stress variations along the fault interface. Due to the increased stress, the radioactive radon comes out from the voids of the rocks, ionizes the atmospheric air, which leads to the release of latent heat, and can be observed in the form of anomalous drop in RH and rise in OLR. Prior to the occurrence of Central Italy region earthquakes of the year 2016 (M > 6.0), the above-mentioned parameters have shown a significant variation than ± 2σ level.

Investigation on the potential utilization of zeolite as an internal curing agent for autogenous shrinkage mitigation and the effect of modification

This paper presents an experimental investigation on the potential utilization of one natural zeolite as an internal curing agent for mitigation of self-desiccation and the subsequent autogenous shrinkage of cement paste with low w/b ratio (0.25). Incorporation of 20% zeolite by mass leads to higher internal relative humidity (90.4%) during the first 7 d compared to that of control sample (78.1%). It is indicating that the zeolite under investigated shows partially elimination effect on the self-desiccation and the autogenous shrinkage as well based on the time-zero defined by the onset of internal relative humidity drop. To obtain improved internal curing property, attempts have been done to modify the pore structure of zeolite by acid treatment and/or thermal treatment. However, both nitric acid treatment and thermal treatment shows negative effect on the improvement of internal curing property of zeolite. Because nitric acid treatment tends to increase the BET surface area of zeolite by increasing the volume of 2–7 nm pores, and the thermal treatment tends to reduce the porosity rather than to enlarge the pore size of zeolite.

Application of a ventilation fan-misting bank on pigs kept in a stationary trailer before unloading: Effects on trailer microclimate, and pig behaviour and physiological response

The aim of this study was to evaluate the effectiveness of water misting with forced ventilation on a stationary trailer on internal vehicle ambient conditions, and behavioural and physiological response of market pigs. During 6 shipments, two identical 2-axle pot-belly trailers transported 191 pigs each (126 ± 5 kg BW) to the same slaughter plant (135 km). On arrival, trailers were kept stationary in the yard for 30 min before unloading. One trailer was positioned along a fan-misting bank (PBVM), while the other trailer had no access to this cooling system (PBC). The PBVM treatment consisted of 10 min of fan-assisted ventilation (phase 1, P1) followed by 10 min of ventilation and water misting (phase 2, P2) and a final 10 min of ventilation (phase 3, P3). Within each trailer, 4 compartments (rear-top [C4], front-middle [C5], center-middle [C7], and front-bottom [C9]) were chosen for data collection. The air temperature (T) and relative humidity (RH) were monitored using data loggers. The percentage of lying pigs during each phase, and the latency to lie down and the frequency of drinking during lairage were calculated. Gastrointestinal tract temperature (GTT) and exsanguination blood lactate, hematocrit, creatine kinase and cortisol concentrations were assessed. Data from the last 5 min of P1 (wait 1), P2 (wait 2), and P3 (wait 3) were analysed. In wait 1, the application of the fan-assisted ventilation resulted in lower (P ≤ 0.05) T and temperature-humidity index (THI) in the PBVM compared to the PBC. A greater (P ≤ 0.05) drop in RH was recorded in C5 and C7 of the PBVM compared to the same compartments in the PBC. In wait 3, T and THI were lower (P < 0.001) in PBVM compared to PBC, but the RH was higher (P < 0.01). Pigs from C4 in the PBVM had a greater (P < 0.001) activity during phases 2 and 3, and a reduced latency to lie down in the lairage pen compared to the same compartment in the PBC (P ≤ 0.05). A higher (P ≤ 0.05) GTT drop was recorded until 1 h after lairage in pigs located in PBC compared to those transported in PBVM. Although the efficiency of the fan-misting bank varied by compartment location, this cooling system appears to be effective in improving the trailer internal thermal environment and thermal comfort of pigs kept in a stationary trailer.

Mathematical Modelling of Drying Kinetics of Wheat in Electron Fired Fluidized Bed Drying System

The conventional method of electrical heating is replaced by electron firing system. The drying kinetics of wheat is studied using electron fired fluidized bed dryer. The results are simulated by using ANSYS. It was observed that the graphs are in agreement with each other. Therefore, the new proposed electronic firing system can be employed instead of electrical firing. It was observed that the drop in Relative Humidity in case of Electrical heating is 68.75% for temp reaching up to 70° C in 67 sec for pressure drop of 13 psi while for the electronic Firing system it is 67.6 % temp reaches to 70° C in 70 sec for pressure drop of 12.67 psi. As the results are in agreement with each other it was concluded that for the grains like wheat which has low initial moisture content both systems can be used.