Browsing by Subject "Moisture"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Hygrothermal Performance of Residential Cantilevered Floors
    (2014-05) Stone, Richard Byron
    This field investigation was designed to compare three insulation strategies commonly used in residential cantilevered floors. The first objective is to determine floor surface temperatures above insulated cantilever cavities, with respect to occupant thermal comfort. The second objective is to determine moisture behavior within insulated cantilever cavities, with respect to durability. The experimental set-up was installed in the cantilevered floor of an existing Minnesota home. The first six months of investigation, from mid-summer into early winter, provided data for analysis and discussion presented in this thesis. Investigation results support the view that cantilevered floor cavities open to adjacent conditioned space have warmer floor surfaces above them. Condensation and wetting in some cantilever cavities during colder weather suggests that durability risks are increased in cavities where there is air movement through the thermal insulation. Further investigation is expected to provide a more comprehensive representation of the annual hygrothermal cycle.
  • Thumbnail Image
    Item
    On impedance based RF dielectric sensors and applications in agricultural materials.
    (2010-08) Braun, Joshua D.
    Increasing numbers of commercially available sensors claim to use the dielectric response of grains and other agricultural materials to sense moisture and additional properties. A review of past and current research in this area gives a basis for investigating the efficacy and potential of one such instrument. A variety of materials, including corn, soybeans, wheat, ground feed, and soils were examined. Potential factors for varietal classification within and material type classification between samples was determined to be impractical due to the strong confounding effect of moisture dependence. Sensor electrode topology was briefly touched on, raising interesting questions about effects of geometry in dielectric sensors. The effect of material presentation was also evaluated for both static and flowing samples. Using continuously flowing samples, several varieties of corn were tested to evaluate existing density independent moisture functions and density functions. The results verified the effectiveness of many functions previously only studied in the microwave range for radio frequency instruments. In addition, a new density prediction function was discovered to have significantly better performance at radio frequencies.