Moisture Transmission Research Articles

Influence of Soil Moisture Transmission Scheme Improvement in CLM4.0 on Simulation of Land Surface Process in Qinghai-Xizang Plateau

Using the Community Land Model version 4.0(CLM4.0) and the observed meteorological data at Maqu station in the Qinghai-Xizang Plateau from 25 May to 31 December 2010 as the forcing data,several simulation experiments have been done.After evaluating the model simulation performance,the model sensitivity to the sand content and the effect of soil moisture transmission scheme improvement on the simulation of land surface process in the Qinghai-Xizang Plateau,it is found that the model can reflect the variation trend of soil temperature and moisture,surface radiation,turbulance energy at Maqu station,but the simulated soil temperature is low and sensible heat flux is too large.The increase of the sand content will decrease the water holding capacity of soil,which leads to the sensible heat flux increasing and latent heat flux decreasing in summer.The organic matters added in CLM4.0 have an important influence on the simulation of both soil temperature and moisture,however,the modified Richards equation and runoff parameters affect much more the simulation of soil moisture,which is a guide to the improvement of other land surface models.

Use of aluminum‐coated interlayers to develop a cold‐protective fibrous assembly

ABSTRACTIn this article, we report on an experimental investigation of the thermal insulation and moisture vapor resistance of a thermal insulation assembly consisting of polyester battings and metal‐coated thin nonwoven interlayers. Because of the blocking of radiation by the coated metal nanoparticles, the thermal radiative conductivity of the interlayer decreased from 0.0249 to 0.0194 W/m K after coating. We found that the thermal insulation of the fibrous assembly could be greatly improved without any significant effect on the moisture transfer through the incorporation of metal‐coated interlayers between the fibrous battings in appropriate patterns. The thermal resistance of the assembly increased gradually with increasing number of incorporated interlayers until it reached a plateau. The presence of more metal‐coated interlayers closer to the hot (heat‐source) side was beneficial to higher thermal insulation. The moisture vapor resistance of the assembly showed no significant changes with increasing number of interlayers. The incorporation of three interlayers showed the best thermal insulation properties with little effect on the moisture transmission. This kind of thermal insulation assembly will have significant advantages in cold‐protective clothing because of its high insulation properties and breathability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40205.

In situ forming antibacterial dextran blend hydrogel for wound dressing: SAA technology vs. spray drying

This study focuses on designing microparticulate carriers based on high-mannuronic alginate and amidated pectin blend loaded with gentamicin sulphate able to move rapidly from dry to soft hydrogel. Supercritical assisted atomization was used to produce microparticles in form of dry powder and characteristics were compared with those obtained by spray-drying. Particles with very high encapsulation efficiency (∼100%) and small diameter (less than 2μm) showed good flowability and high fluid uptake enabling wound site filling and limiting bacterial proliferation. Moisture transmission of the in situ formed hydrogel was about 95g/m2h, ideal to avoid wound dehydration or occlusion phenomena. All formulations presented a burst effect, suitable to prevent infection spreading at the beginning of the therapy, followed by prolonged release (4–10 days) related to drug/polymers ratio. Antimicrobial tests showed stronger effect than pure GS over time (up-to 24 days) and the ability to degrade preformed biofilms, essential to properly treat infected wounds.

Thermophysiological comfort characteristics of plated knitted fabrics

Thermophysiological comfort properties of polyester elastane-plated fabric have been studied by varying the polyester filament shape factor, elastane linear density, and fabric loop length. Thermal and evaporative resistances were measured using sweating guarded hot plate. Absorption and wicking properties were measured using M/K GATS. Moisture management properties were measured by moisture management tester. Multilinear regression equations were calculated for all the properties by using generalized linear model (GLM). The hypothesis tests were performed on estimated model (GLM) and the probability values (p-values) were calculated for each variable. Most of the heat and moisture transmission properties were found to be significantly affected by all three variables (i.e. filament shape factor, elastane linear density, and fabric loop length) at 95% level of significance.

Characterization of Moisture Diffusion into Polymeric Thin Film

The moisture within polymeric material typically used in electronic devices causes popcorn failures due to the vapor pressure in addition to the thermal stress. The knowledge of characteristics of moisture diffusion into the material is essential in the optimal material development and reliability assessment. The clarified procedures for measuring moisture sorption properties in a thin film form of semicrystalline polyethylene terephthalate (PET) using thermo-gravimetry and differential permeation are studied. The effective diffusivity of moisture into the material obtained from both the moisture transmission through the material and the solubility of moisture is proposed as a reliable method than the direct half time approximation over various water activities and temperatures. The parameterized isothermal desorption process according to Arrhenius equation investigates the possible effect of moisture on the polymer matrix as a form of bound water with polarity. The activation energy of diffusivity and solubility required for moisture diffusion into the material is discussed together with the required energy for evaporation of water.

Atmospheric Moisture Variability and Transmission of Hemorrhagic Fever with Renal Syndrome in Changsha City, Mainland China, 1991–2010

BackgroundThe transmission of hemorrhagic fever with renal syndrome (HFRS) is influenced by environmental determinants. This study aimed to explore the association between atmospheric moisture variability and the transmission of hemorrhagic fever with renal syndrome (HFRS) for the period of 1991–2010 in Changsha, China.Methods and FindingsWavelet analyses were performed by using monthly reported time series data of HFRS cases to detect and quantify the periodicity of HFRS. A generalized linear model with a Poisson distribution and a log link model were used to quantify the relationship between climate and HFRS cases, highlighting the importance of moisture conditions. There was a continuous annual oscillation mode and multi-annual cycle around 3–4 years from 1994 to 1999. There was a significant association of HFRS incidence with moisture conditions and the Multivariate El Niño–Southern Oscillation Index (MEI). Particularly, atmospheric moisture has a significant effect on the propagation of HFRS; annual incidence of HFRS was positively correlated with annual precipitation and annual mean absolute humidity.ConclusionsThe final model had good accuracy in forecasting the occurrence of HFRS and moisture condition can be used in disease surveillance and risk management to provide early warning of potential epidemics of this disease.

Modeling and Simulation of Moisture Transmission through Fibrous Structures Part II: Liquid Water Transmission

Modeling and Simulation of Moisture Transmission through Fibrous Structures Part II: Liquid Water Transmission

Modeling and Simulation of Moisture Transmission through Fibrous Structures Part I: Water Vapour Transmission

Modeling and Simulation of Moisture Transmission through Fibrous Structures Part I: Water Vapour Transmission

Simulation of Eco-hydrological Process in Hani Terrace wetland

Hani terrace is a precious legacy which Hani people created from generation to generation; it has been in good running for over thousand years. It is a complete new attempt to reveal the good running mechanism of Hani terrace from the eco-hydrological process, which is to reveal the terrace's interactive influence relationship with local ecological effect from the core of its hydrological element. In this article, on the basis of eco-hydrology process, the paper initially constructs a rainfall interception model, evapotranspiration model, plant - soil moisture transmission model, groundwater model, and eco-hydro-chemistry process simulation model, finally finds out initially ecological effect of Hani terrace wetland based on all models.

Humidity, Pressure, and Temperature Measurements in an Interdigitated-Flow PEM Hydrogen Fuel Cell

In situ measurements of humidity, temperature, and pressure are demonstrated for a polymer electrolyte membrane (PEM) fuel cell of interdigitated gas flow channel layout. Sensors are embedded at the flowfield edges, sampling air, and hydrogen at several positions along the flow channels. The measurements provide, for the first time, real-time localized data for this configuration of fuel cell. The results show that, for the interdigitated flowfield, moisture freely permeates through the membrane electrode assembly (MEA). This is in contrast to lower net moisture transmission through the same MEA used in a serpentine flowfield.

Study on Wearability of Multi-Component Blended Fabrics

In order to study the wearability of multi-component blended fabrics, there are 9 kinds of fabrics which belong to A, B and C three series were woven. They were blended with different proportions e.g. PTT, PLA, Cooldry, triangular shaped polyester yarn, cotton, hemp, viscose, conductive filament, and so on. Anti-pilling property, crease recovery, drapability, moisture transmission and air permeability of the fabrics were tested and analyzed. From the test results, following conclusions can be gotten. 1) The anti-pilling property is good for fabrics with tighter weave construction; 2) The crease recovery is good for fabrics with smaller weft density; 3) The moisture permeability is good for fabrics with smaller tightness; 4) The crease resistance, drapability, moisture permeability and air permeability of the fabrics can be improved by looser weave construction and smaller binding point.

Compression behavior of warp-knitted spacer fabrics for cushioning applications

Cushioning materials generally absorb kinetic mechanical energy under compression actions at a relatively constant stress over a large range of displacement. However, cushioning materials widely used today are polyurethane (PU) foams with low moisture transmission. As a new class of three-dimensional textile structures, warp-knitted spacer fabrics not only have much better moisture transmission property than PU foams, but also have the similar cushioning performance if appropriate structural parameters are adopted. This paper reports an experimental study on the compression behavior of a series of warp-knitted fabrics made for cushioning applications. These fabrics were produced on a double-needle bar warp knitting machine of gauge 18 by varying different structural parameters including spacer yarn inclination angle and fineness, fabric thickness, and outer layer structure. Both the compression stress-strain curves and energy efficiency diagrams from the testing results were used to analyze the compression behavior of these fabrics and the effect of each structural parameter. The results indicate that warp-knitted spacer fabrics are an ideal class of the energy absorbers for cushioning applications and their energy-absorption capacity can easily be tailored to meet specific end-use requirements by simply varying their structural parameters with the help of efficiency diagrams.

The effect of added fullness and ventilation holes in T-shirt design on thermal comfort

This paper reports on an experimental investigation on the effect of added fullness and ventilation holes in T-shirt design on clothing comfort measured in terms of thermal insulation and moisture vapour resistance. Four T-shirts in four different sizes (S, M, L, XL) were cut under the traditional sizing method while another (F-1) was cut with specially added fullness to create a ‘flared’ drape. A thermal manikin ‘Walter’ was used to measure the thermal insulation and moisture vapour resistance of the T-shirts in a chamber with controlled temperature, relative humidity and air velocity. The tests included four conditions: manikin standing still in the no-wind and windy conditions and walking in the no-wind and windy condition. It was found that adding fullness in the T-shirt design (F-1) to create the ‘flared’ drape can significantly reduce the T-shirt's thermal insulation and moisture vapour resistance under walking or windy conditions. Heat and moisture transmission through the T-shirt can be further enhanced by creating small apertures on the front and back of the T-shirt with specially added fullness. Statement of Relevance: The thermal comfort of the human body is one of the key issues in the study of ergonomics. When doing exercise, a human body will generate heat, which will eventually result in sweating. If heat and moisture are not released effectively from the body, heat stress may occur and the person's performance will be negatively affected. Therefore, contemporary athletic T-shirts are designed to improve the heat and moisture transfer from the wearer. Through special cutting, such athletic T-shirts can be designed to improve the ventilation of the wearer.

A study on thermophysiological comfort properties of fabrics in relation to constituent fibre fineness and cross-sectional shapes

The present study reports the effect of linear densities and profiles of polyester fibres on the physiological properties of their fabrics. Four different polyester fibre finenesses along with microdenier and four cross-sectional shapes (circular, scalloped oval, tetrakelion and trilobal) were selected to produce two sets of 2/1 twill fabrics; one composed of 100% polyester and the other 67:33 P/V blends. In studying the thermophysiological component of the clothing comfort, heat, air and moisture transmission characteristics of the fabrics were assessed. The principal thermal properties, such as thermal absorptivity, thermal resistance and thermal conductivity, were experimentally evaluated, using the Alambeta instrument. The study of the obtained results established the fabrics of non-circular cross-sections as against circular ones, and increase in the linear density results in higher thermal resistance, lower thermal conductivity and lower thermal absorptivity. Wicking behaviour of fabrics was studied under two conditions–wicking from an infinite liquid reservoir (transverse wicking) and wicking from a finite liquid reservoir (single drop wicking into the fabrics). Increase in fibre linear density enhances transplaner wicking but slows down the spreading speed of water drops. Air permeability and moisture vapour permeability are found to be positively correlated with fibre decitex. The role of fibre cross-sectional shapes in influencing mass-flow characteristics is quite considerable. Use of non-circular polyester in place of a circular one augments the wickability of liquid water along with the permeability of air and moisture vapour through the fabrics, revealing their high porosity, which assists air and moisture to propagate. Mixing viscose into polyester brings down the air permeability and moisture vapour transmission rate (MVTR) of fabrics. Results show that moisture absorption of viscose is an important factor in influencing the moisture transport characteristics including both wickability and MVTR of 100% viscose and P/V-blended fabrics.

A Study on Moisture Permeation through Fabrics (Part 5) Air Permeation and Moisture Transmission of Polyester Fabrics

A Study on Moisture Permeation through Fabrics (Part 5) Air Permeation and Moisture Transmission of Polyester Fabrics

Thermal Protective Performance and Moisture Transmission of Firefighter Protective Clothing Based on Orthogonal Design

This study is to investigate thermal protection and moisture transmission of firefighter clothing and how combinations of materials influence the thermal protection and moisture transmission. An orthogonal design is applied for planning the experiment. Eight different material combinations, which simulate three-layer firefighter protective clothing system, are studied. The thermal protective performance (TPP) and water vapor transmission rate of combinations are tested. The experiment data are discussed by analysis of range and variance. Meanwhile, influence of each layer on clothing performance is also studied. Results show that outer shell fabric and moisture barrier layer have significant effects on TPP and moisture transmission property, respectively.

Hygroscopic Behaviour Modelling of Syntactic Foams in the Presence of Trapping and Diffuse Interfaces

In order to determine the role of reinforcement–matrix interfaces in the infiltration of water molecules within a composite material, we introduced a very thin layer that was highly diffusive and trapping between reinforcements and matrix. A finite element discretization of such an extremely thin surface layer poses numerical difficulties. To resolve this problem, we sought to substitute this interfacial surface, whose thickness is very low, with a thicknessless interface which has equivalent diffusion behaviour. Using asymptotic development techniques, we also established a minimum interface limit which is asymptotically equivalent to the problem of moisture transmission through a very thin highly diffusive and trapping layer. Using the method of homogenization environments periodicals and model Langmuir, we determined hygroscopic behaviour equivalent to the syntactic foams while taking account of interface law proposed. Determination of the diffusion coefficients and trapping is then compared with the experimental results.

Moisture Flow through Blended Fabrics – Effect of Hydrophilicity

Moisture flow through blended material is a complex phenomenon. Clothing should possess good water vapour as well as liquid moisture transmission property, for providing the thermophysiological clothing comfort. The clothing should take up the moisture from the skin as well as transmit it to the atmosphere. Higher hydrophilicity of a material is known for good absorption, but how it really helps to transmit the moisture, has been studied in the present work. Polyester and viscose have been chosen as the blending fibers and 8 fabrics with different blend proportions were developed. Water vapour transmission of the fabrics was measured using the PERMETEST. Liquid water transmission property of the fabrics was examined using a gravimetric inplane wicking tester and a vertical wicking tester. From the experimental result it has been observed that water vapour permeability and absorbency of the material increases with the increase in number of hydrophilic group in the material, but it has an adverse effect on the liquid moisture transmission behavior of the material. The vertical as well as horizontal wicking of the material decreases with the increase in viscose proportion in the polyester/viscose blended fabrics.

Studies on moisture transmission properties of PV-blended fabrics

Moisture transmission properties are most important for fabric comfort. We have studied the moisture transmission properties of the plain-woven fabric produced with polyester–viscose-(PV) blended yarns. PV-blended yarns of varying blend proportion, yarn count and twist levels have been used for fabric manufacture. A three-variable Box and Behnken factorial design technique has been used to study the interaction effects of the above variables on the aforesaid characteristics of fabrics. The interactive effect of these three variables on the air permeability, water vapour permeability, in-plane wicking and vertical wicking of PV-blended fabrics has been studied and the response surface equations for all the properties have been derived; also, the design variables have been optimized for all the moisture transmission-related properties. Most of the moisture transmission characteristics were found to be affected significantly by blend proportion, count and twist levels at 95% level of significance with the present variables.

Effect of compression on the liquid absorption of Chinese fir wood with different heartwood-to-sapwood ratios

In this study, the Chinese fir (Cunninghamia lanceolata Hook.) specimens with different ratios of heartwood thickness to sapwood thickness (HS) were radially compressed at different compression speeds, and then absorbed amine copper quat-type D (ACQ-D) preservative solution under the negative-pressure produced by the recovery of compression deformation. The liquid uptake (Al), the recovery rate of compression deformation (Rs) and the chemical absorption (Ac) of samples were determined, as well as the overall distribution of density and effective component of ACQ-D (i.e., copper in wood), the mechanical properties such as surface hardness were also measured. The Al, Rs, Ac values of compressed samples including the whole heartwood ones were higher than those of uncompressed samples, showing that radial compression had an obvious positive effect on improving the liquid absorption of heartwood. Higher compression speed of 3 mm·min−1 is preferable since the samples with that speed could reach the highest Al and Ac; in addition, more deformation fixation has been produced possibly because of the faster heat and moisture transmission at the higher compressed speed, and more bonds of hydrophobic nature were formed, leading to the higher surface hardness and density. A consistent tendency of the density distribution and the copper retentions along the thickness direction could be explained that the layers with higher density have smaller volumes of void areas, and more chemicals were absorbed and fixed, resulting in the higher copper retentions.