<p> This study assessed biomass and carbon (C) allocation in a chronosequence of four White pine (Pinus strobus L.) plantation forests planted in 2002 (WPP02), 1989 (WPP89), 1974 (WPP74), and in 1939 (WPP39), in southern Ontario, Canada. A plotbased inventory and destructive tree sampling were conducted in 2004 to assess allocation of oiomass and C in ecosystem components, as well as allometry of tree biomass. Seasonal and annual patterns of litter and branch fall were also determined.</p> <p>Individual tree biomass components as well as sapwood area have strong site specific allometric relationships with tree diameter. Except for foliage biomass, strong single allometric equations could also be obtained across all sites and stand ages. Whereas allometry of individual tree components may be affected by site conditions and stand age, total tree biomass solely depended on tree diameter. This suggests that total biomass of White pine may be predicted from single allometric equations with DBH as input variable across sites and even across regions.</p> <p>Relative partitioning of tree biomass components was strongly related to tree age. Stem biomass gains major importance with increasing tree age at the cost of all other components comprising 69% of total tree biomass after 65 years. Whereas site conditions influenced the absolute amount of biomass and allometry of individual tree components, they did not affect their relative partitioning </p> <p> Only biomass of trees, woody debris, and small roots (2-5mm) showed agerelated patterns by increasing with greater stand age. Increase in tree biomass was highest during the early decades after establishment and after thinning practices. </p> <p> C storage in forest floor was 0.8, 7.5, 5.4, and 12.1 t C ha⁻¹ and C content in mineral soil was 37.2, 33.9, 39.1, and 36.7 t C ha⁻¹ at WPP02, WPP89, WPP74, and WPP39, respectively. Biomass of roots < 5mm was 0.3, 6.0, 8.9, and 7.5 t ha⁻¹ at WPP02, WPP89, WPP74 and WPP39, respectively. Annual litter fall was age independent with 5, 3 and 4 t ha⁻¹ y⁻¹ at WPP89, WPP74, and WPP39, whereas branch fall increased with age and basal area to 0.007, 0.17, and 1.38 t ha⁻¹ y⁻¹ at WPP89, WPP74, and WPP39, respectively. Average total tree biomass was 0.4, 67, 122, and 547 kg per tree with an uncertainty of less than 1, 5, 3, and 1 % at WPP02, WPP89, WPP74 and WPP39, respectively. Belowground to aboveground tree biomass ratio was 0.35, 0.19, 0.14, and 0.17 forWPP02, WPP89, WPP74, and WPP39, respectively, which suggests a considerable amount of C stored in root biomass. Above and below ecosystem C increased with an average rate of 1.9 and 0.5 t C ha⁻¹ y⁻¹ across the chronosequence, reaching 122 and 66 t C ha⁻¹ y⁻¹ respectively at age 65. Total net ecosystem C accumulation between age 2 and 65 was 147 t C ha⁻¹. Inventories limited to stem biomass may underestimate total tree biomass by up to 3 5% and total ecosystem C by up to 62%.</p> <p> Thus, estimations of C storage in forest ecosystems should include all above and belowground C pools, and its accuracy may be improved by predicting total treebiomass with allometric equations related to stand age and tree diameter.</p> / Thesis / Master of Science (MSc)

Small diameter trees refer to the trees with diameter at breast height (DBH) ranging from 5 to 11 inches. This research focuses on the resource analysis and spatial distribution of small-diameter tree (SDT) volume in Mississippi by a set of grouping variables including DBH class, species, stand size, forest cover type, ownership, and county groups. Regression and spatial interpolation techniques were used to predict the SDT volume for pine, hardwood, and mixed forest covers. Regression analysis resulted in a low regression coefficient (R2) without inventory data for all the forest cover types. The mean SDT volume to the total volume was greatest for pine (0.6), followed by mixed (0.4), and hardwood (0.3) forest cover. Non-spatial estimates indicated the total volume within respective groups. The spatial and non-spatial estimates of SDT resources can guide forest management personnel to effectively focus their management efforts.

<p> Silicon solar cells were produced using inexpensive techniques for obtaining high efficiencies. Large area cells were made with efficiencies greater than 10% (AM1) which were subsequently mounted on a Solar panel for future evaluation. </p> / Thesis / Master of Engineering (MEngr)

<p> In experimental microdosimetry one of the goals is to measure the absorbed dose in microscopic volumes of tissue. The traditional spherical tissue-equivalent proportional counter (TEPC) is the most common detector currently used for microdosimetry. A new microdosimetric detector based on a thick gas electron multiplier (THGEM) was developed. To investigate the feasibility of the THGEM type detector for microdosimetry, a prototype detector was designed and manufactured. The THGEM detector is robust, easy to manufacture and is cost effective. The THGEM foil is composed of a thin FR4-epoxy insulator coated with copper on both sides. The THGEM contains 32 holes each with a diameter of 0.35 mm and pitch of 0.64 mm. The sensitive volume of the detector is a right cylinder with a diameter of ~5 mm and height of ~5 mm and is located in the center of the detector. Systematic tests were conducted at the McMaster Accelerator Laboratory to investigate its overall performance. A neutron-gamma ray radiation field was generated using the 7Li(p,n) reaction. The detector was operated at low bias voltages initially to test the stability and then the relative multiplication gain was measured as a function of the operating high voltage. The detector performance was observed with different THGEM insulator thicknesses ranging from 0.12 mm to 1.48 mm. The multiplication gain was assessed and both neutron and gamma-ray radiation was detected by the THGEM detector. The spectra obtained with the THGEM detector were analyzed and compared to the data collected with the standard spherical TEPC. The investigations provided information about the THGEM detector operation for microdosimetry and the THGEM microdosimetric spectra observed are comparable to the standard TEPC data.</p> / Thesis / Doctor of Philosophy (PhD)

The current study is an experimental and analytical investigation of JIB within the nucleate and transition boiling regimes. This study focuses on studying JIB within the stagnation zone of a free water jet. An experimental setup has been designed and built at the Thermal Processing Laboratory (TPL) with the capability of carrying out boiling experiments at heat fluxes up to 12 MW/m2. The JIB curves have been obtained under steady-state conditions for a wide range of jet conditions, higher than those considered during previous JIB studies. The effect of jet velocity, up to 3.8 m/s, and degree of subcooling, up to 49 °C, on the JIB curve has been studied. The results showed that both jet velocity and degree of subcooling have a weak effect on the nucleate boiling regime and significantly affect the transition boiling regime. Bubble dynamics under the impinging jet within the nucleate boiling regime and the stability of the vapor layer within the transition boiling regime have been investigated. An analytical mechanistic model, based on force balance and thermal balance equations, has been developed to predict the bubble growth rate and the BDD. The developed model was validated using current experimental data. The model gave a relative deviation of 17.8 %. Results of the mechanistic model within the stagnation zone showed that, amongst the three heat transfer mechanisms that affect bubble growth (i.e., the microlayer evaporation, the heat from the superheated layer, the convection heat loss to subcooled liquid), the microlayer evaporation is the most significant contributor to the rate of bubble growth. The current work conducted within the transition boiling regime was focused on the determination of the total wall heat flux within the stagnation zone, both experimentally and analytically. Steady-state experiments have been carried out during which the vapor layer stability was examined. The vapor layer breakup frequency was measured using a fiber-optic probe. Experiments were conducted at a jet velocity of 1 m/s and degrees of subcooling between 11 and 49 ºC. / Thesis / Doctor of Philosophy (PhD)

Southern bottomland hardwood forests lack effective growth and yield predictive models primarily due to the complexity of the ecosystems. These models are important tools for relative comparison of management schemes and making sound management decisions to obtain optimal future yields. Starting in 1982, 150 red oak-sweetgum bottomland hardwood growth and yield plots were established in northern and central parts of Mississippi. These plots were remeasured in 1988, 1992, 1993, 2005, 2006, and 2007 along with the addition of new plots. A diameter distribution model was developed from stand level component equations constructed in a previous study (Iles 2008; Schultz et al. 2010). The equations created performed well when testing the predicted survival and diameter growth against the observed data. The resulting growth and yield system will be a basis for better decision making in the comparison of management alternatives as well as increased conservation and efficient utilization of wood products.

There have been several studies that aim to determine the most superior Weibull parameter recovery approach of specifying a given forest stand’s Weibull diameter distribution, but no consensus has been made. The lack of agreement could be attributed to studies using different moments/percentile prediction models as well as using different plot size data. This study investigates how plot size and prediction model form affects the performance for moments, hybrid, and percentile Weibull parameter recovery approaches. Five plot sizes and three moments/percentile prediction models were used to determine their effects. Weibull parameters were calculated using each recovery method for each plot size and moments/percentile prediction model combination. Each combination’s diameter distribution was recovered and assessed using absolute error index. Results showed that plot size affected rank of precision for parameter recovery methods. Findings suggest that order statistics may be important in recovering Weibull distribution parameters from stand diameter summary statistics.

No description available.

No description available.

No description available.