Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 21 for “"air permeability"”.
-
Longitudinal air permeability of lodgepole pine
The longitudinal air permeabilities of the wood of 1116 specimens from 279 trees, two sapwood and two heartwood replicates, representing two varieties of lodgepole pine (Pinus contorta, vars. latifolia and murrayana) were measured with a steady state apparatus. It was found that the mean ratio of …
-
Design, performance, and analysis of a multi-level air permeability test
… system to identify zones most conductive to air transport and quantify kair in sequential soil layers is presented. A multi-level extraction well, with alternating solid and screened sections, was utilized to characterize multi-layered media. The field site, located in the Carolina Slate Belt …
-
Development of a Method for Measuring Rock Mass Air Permeability and Applications to Underground Mining
… hydraulic properties, however, flow tests for permeability are challenging due to inconsistent flow. Pumping tests are not feasible due to associated stability concerns. Methods using air for estimating rock mass hydraulic properties were determined to be the best option for testing. Equipment, …
-
The Effects of Household Fabric Softeners on the Thermal Comfort and Flammability of Cotton and Polyester Fabrics
… to thermal comfort, water vapor transmission and air permeability, were examined. A 3 X 2 X 3 experimental design (i.e., 18 experimental cells) was developed to conduct the research. Three independent variables were selected: fabric softener treatments (i.e., rinse cycle softener, dryer sheet …
-
A comparative study of athletic apparel made from cotton/flax, cotton/polyester, and polyester/flax blends
… such as wicking, vapor transmission, and air permeability. Currently, most sports apparel is made from a blend of polyester or other synthetic fibers. Through examining the uniqueness of natural fibers, such as cotton and flax, the advantages and benefits of using a higher percentage of …
-
Influence of near surface moisture gradients in concrete on 'Autoclam' permeation measurements
… conditions in the concrete on 'Autoclam' air permeability and sorptivity measurements. An analysis of the results indicated a unique relationship between the air permeability and the relative humidity recorded in a 10 mm deep drilled hole. A linear relationship was found between the …
-
Suitability of Casuarina equisetifolia as utility poles in Senegal
… as follows: (1) to determine the longitudinal air permeability of the species with regard to its treatability; (2) to determine the treatability of the wood using a full-cell process; (3) to determine the mechanical properties of the species relative to its use as utility poles in Senegal. The …
-
The modification of fuel cell-based breath alcohol sensor materials to improve water retention of sensing performance
… compared to carbon cloth GDLs due to the lower air permeability. This came at a cost however in that with a lower air permeability, less ethanol vapour would reach the catalytic sites, reducing sensing performance.
-
A study of heat transfer through clothing assemblies
… results. The effects of wind velocity, air permeability and stiffness of the outer fabrics, air permeability and thickness of the inner fibrous battings, and the dimensions of the human body on the clothing thermal insulation have also been examined and discussed. Furthermore, based on …
-
Improving quality on a nonwovens line
… a significant effect on the quality measures--air permeability, caliper, basis weight, and appearance--of the filter media. Then a second experiment was run to study fewer variables in more detail. The data were interpreted with ANOVA and regression models. This research makes three general …
-
The integration of non-destructive test methods in the South African Durability Index approach
… RC [reinforced concrete] structures. The oxygen permeability index (OPI) test is being standardised in South Africa, and has been implemented in a large scale project by the South African National Roads Agency Limited (SANRAL). However, the semi-invasive nature of the test method (due to core …
-
Evaluation of the effect of fines on asphalt concrete
… specific surface area factors using the Blaine air permeability apparatus. By using the factors obtained, the voids in the mineral aggregate (VMA) and asphalt thickness are calculated. The measured specific surface area of the crushed limestone fines is much greater than the values computed …
-
Influence of curing on the properties of concretes and mortars in hot climates
… countries, on the pore size distribution, permeability, water absorption and compressive strength of cement mortars and concretes made with and without pulverized fuel ash (pfa) and ground granulated blast-furnace slag (ggbs). Three 00 environments were chosen as follows: 1) 20C+70%RH, 2) …
-
The effect of winter grazing and a nitrification inhibitor on nitrous oxide emissions and denitrification in a stony soil
Intensive grazing of forage crops by dairy cows is common practice during the winter months in the Canterbury region of New Zealand. Such intensive grazing on wet soil increases the risk of denitrification and the production of the powerful greenhouse gas, nitrous oxide (N₂O). However, at the …
-
Porous titanium felts as alternative metal gas diffusion layers for low temperature PEM fuel cells
… attributed to greater porosity which enhanced air permeability, as well as better ohmic resistance which remained low across thicknesses. Subsequently, a hydrophobic treatment of 5 wt% PTFE was shown to improve performance and flooding resistance of the 400 µm titanium felt relative to the …
-
Ternary combination concretes using GGBS, fly ash & limestone: strength, permeation & durability properties
… (initial surface absorption and sorptivity) and permeability (water penetration and air permeability)) and durability properties (accelerated carbonation and chloride ingress) of the test concrete were also investigated. At 28 days, for low GGBS levels, the binary concretes gave reduced …
-
The relationship between the loop length and properties of some plain weft-knitted fabrics
… increase in loop length leads to an increase in air permeability and percentage weight loss when the fabric subjected to abrasion. It is found that for two-end fabrics the percentage weight loss is non-linearly related to the loop length and this reflects the yarn arrangement within the …
-
Fundamental investigations on the barrier effect of polyester micro fiber fabrics towards particle-loaded liquids induced by surface hydrophobization
… the materials for 20 times no significant impairment of hydrophobic character has been noticed in case of fluorocarbon finishing agents as well as by the surface treated with C2H4 followed by C2F6 plasma (i.e., a two-step technique), wherein a complete loss of hydrophobic effect washing the …
-
Dynamic Botanical Filtration System for Indoor Air Purification
<p>A dynamic botanical air filtration (DBAF) system was developed, tested and modeled for indoor air purification. The DBAF system consisted of an activated-carbon/hydroculture-based root bed for potted-plant, a fan for driving air through the root bed for purification, and an irrigation system for …
-
Evaluation of Moisture Diffusion Theories in Porous Materials
… for structural damage, as well as poor indoor air quality. For these reasons, the need to understand transfer mechanisms and predict moisture transport through building materials has increased over the last couple of decades. Although moisture diffusion phenomenon in the isothermal regime has …
Page 1 of 2