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• 511. [Article] Modification of Lower Plenum Structure for Mixing Promotion during Normal Operation of the High Temperature Gas Cooled Reactor

  Since High Temperature Gas-cooled Reactors are being considered as most promising design of upcoming IV Gen reactors, thus key research areas were identified to address safety aspects of this design. Number ...

  Citation × Citation Citation Abstract Copy Title: Modification of Lower Plenum Structure for Mixing Promotion during Normal Operation of the High Temperature Gas Cooled Reactor Author: Gradecka, Malwina Since High Temperature Gas-cooled Reactors are being considered as most promising design of upcoming IV Gen reactors, thus key research areas were identified to address safety aspects of this design. Number of simulations and experiments need to be conducted in this field. In this study thermal-hydraulics aspects of coolant flow through Lower Plenum (LP) of HTGR were considered. In specific: flow characteristics, risk of temperature stratification in LP and hot streaking. As power profile is non-uniform across the core, jets of coolant exit the core region at different temperatures and enter the LP impinging on LP floor creating possibility of hot spots at LP structure and temperature stratification in the plenum itself. Large local temperature gradients can cause material degradation effects. To address those issues numerical simulation and an experiment were developed. The numerical simulation provides coolant flow velocity and temperature fields. The purpose of this study is developing a method for gas mixing promotion in the Lower Plenum of HTTF to reduce risk of the hot streaking and thermal stratification phenomena during normal operation. Following aspect are being examined: identification of gas flow behavior in lower plenum of HTTF based on CFD simulations, identification of hot streaking issue in the HTTF lower plenum using CFD tools, scooping study for available methods for mixing promotion and computational investigation of efficiency of selected method. Study includes description of experimental setup of HTTF, guidance for LP CFD modeling, results and analysis of CFD simulations and proposition of thermal mixing enhancement using available methods. Title: Modification of Lower Plenum Structure for Mixing Promotion during Normal Operation of the High Temperature Gas Cooled Reactor Author: Gradecka, Malwina Since High Temperature Gas-cooled Reactors are being considered as most promising design of upcoming IV Gen reactors, thus key research areas were identified to address safety aspects of this design. Number of simulations and experiments need to be conducted in this field. In this study thermal-hydraulics aspects of coolant flow through Lower Plenum (LP) of HTGR were considered. In specific: flow characteristics, risk of temperature stratification in LP and hot streaking. As power profile is non-uniform across the core, jets of coolant exit the core region at different temperatures and enter the LP impinging on LP floor creating possibility of hot spots at LP structure and temperature stratification in the plenum itself. Large local temperature gradients can cause material degradation effects. To address those issues numerical simulation and an experiment were developed. The numerical simulation provides coolant flow velocity and temperature fields. The purpose of this study is developing a method for gas mixing promotion in the Lower Plenum of HTTF to reduce risk of the hot streaking and thermal stratification phenomena during normal operation. Following aspect are being examined: identification of gas flow behavior in lower plenum of HTTF based on CFD simulations, identification of hot streaking issue in the HTTF lower plenum using CFD tools, scooping study for available methods for mixing promotion and computational investigation of efficiency of selected method. Study includes description of experimental setup of HTTF, guidance for LP CFD modeling, results and analysis of CFD simulations and proposition of thermal mixing enhancement using available methods. Close

• 512. [Article] Bioenergetics and survival of chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon in heated seawater

  The use of heated seawater for enhancing the culture of Pacific salmon was investigated. Food consumption rate, gross food conversion efficiency, growth rate, and survival of chum (Oncorhynchus keta) and ...

  Citation × Citation Citation Abstract Copy Title: Bioenergetics and survival of chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon in heated seawater Author: Kepshire, Bernard Michael The use of heated seawater for enhancing the culture of Pacific salmon was investigated. Food consumption rate, gross food conversion efficiency, growth rate, and survival of chum (Oncorhynchus keta) and pink (O. gorbuscha} salmon fed to satiation were determined in relation to water temperature and body weight. Both species of salmon were raised at temperatures of 55°, 60°, 65°, and 70°F. The highest food consumption rate, gross food conversion efficiency, growth rate, and survival of chum salmon occurred at temperatures of 65°, 55°, 55°-65°, and 55°F, respectively, while those of pink salmon occurred at 65°, 55°-65°, 60°-65° and 55 -60°F, respectivety. The response to all conditions measured was poorest for chum and pink salmon at 70°F. Pink salmon generally had a higher food consumption rate, gross food conversion efficiency, and growth rate than chum salmon. Food consumption rate, gross food conversion efficiency, growth rate, and survival of chum and pink salmon decreased as body weight increased. As body weight increased, food consumption rate, gross food conversion efficiency, and growth rate generally decreased more at 60°-65°F than at 55°F for chum salmon, and more at 65°-70°F than at lower temperatures for pink salmon. Survival was influenced by behavior and disease in addition to temperature. Diseases encountered were bacterial kidney disease and vibriosis, of which the former was most prevalent. Chum and pink salmon can be cultured in heated seawater at temperatures not exceeding 65°F. Good growth (>5% gain in body weight/day) and survival (60-100%) can be expected. Title: Bioenergetics and survival of chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon in heated seawater Author: Kepshire, Bernard Michael The use of heated seawater for enhancing the culture of Pacific salmon was investigated. Food consumption rate, gross food conversion efficiency, growth rate, and survival of chum (Oncorhynchus keta) and pink (O. gorbuscha} salmon fed to satiation were determined in relation to water temperature and body weight. Both species of salmon were raised at temperatures of 55°, 60°, 65°, and 70°F. The highest food consumption rate, gross food conversion efficiency, growth rate, and survival of chum salmon occurred at temperatures of 65°, 55°, 55°-65°, and 55°F, respectively, while those of pink salmon occurred at 65°, 55°-65°, 60°-65° and 55 -60°F, respectivety. The response to all conditions measured was poorest for chum and pink salmon at 70°F. Pink salmon generally had a higher food consumption rate, gross food conversion efficiency, and growth rate than chum salmon. Food consumption rate, gross food conversion efficiency, growth rate, and survival of chum and pink salmon decreased as body weight increased. As body weight increased, food consumption rate, gross food conversion efficiency, and growth rate generally decreased more at 60°-65°F than at 55°F for chum salmon, and more at 65°-70°F than at lower temperatures for pink salmon. Survival was influenced by behavior and disease in addition to temperature. Diseases encountered were bacterial kidney disease and vibriosis, of which the former was most prevalent. Chum and pink salmon can be cultured in heated seawater at temperatures not exceeding 65°F. Good growth (>5% gain in body weight/day) and survival (60-100%) can be expected. Close

• 513. [Article] On the reduction and interpretation of ocean-floor temperature and heat flow data

  In this thesis, the interpretation and reduction of ocean heat flow measurements are discussed on the basis of theoretical models. The instrument effect x heat flow measurements is investigated for the case ...

  Citation × Citation Citation Abstract Copy Title: On the reduction and interpretation of ocean-floor temperature and heat flow data Author: Shih, Keh-gong In this thesis, the interpretation and reduction of ocean heat flow measurements are discussed on the basis of theoretical models. The instrument effect x heat flow measurements is investigated for the case of long period measurements by studying the heat conduction along the measurement probe for both steady and unsteady state bottom temperatures. This effect is found to be unimportant. Measurement errors due to recent bottom temperature transients are studied and the possible magnitude of such errors is estimated. Moreover, effects of climatic variation on the ocean floor temperature are estimated on the basis of diffusion models. It is shown that climatic variations with periods longer than one thousand years will be unattenuated and will affect the entire ocean floor. The perturbation method is used to study the effects of an irregular topography and a variable thickness of ocean floor sediments on the heat flow. Some special examples are given to provide a comparison between the perturbation solutions and exact solutions of similar problems. The perturbation method is also applied to a buried body with different thermal conductivity from its surroundings and the reliability of the perturbation solution is examined. Heat flow anomalies due to heat transport by magma intruded into crustal layers is studied by solving the heat conduction equation. It is shown that magmatic intrusions can lead to very large surface heat flow anomalies. Finally, the possibility of deriving the ocean floor thermal gradient on the basis of on-ship measurements performed on sediment cores is investigated. The results appear positive. The temperature variations in flowing wells and the temperature variation in a cylindrical sediment core influenced by the movement of water along the axis of the core are also studied. Title: On the reduction and interpretation of ocean-floor temperature and heat flow data Author: Shih, Keh-gong In this thesis, the interpretation and reduction of ocean heat flow measurements are discussed on the basis of theoretical models. The instrument effect x heat flow measurements is investigated for the case of long period measurements by studying the heat conduction along the measurement probe for both steady and unsteady state bottom temperatures. This effect is found to be unimportant. Measurement errors due to recent bottom temperature transients are studied and the possible magnitude of such errors is estimated. Moreover, effects of climatic variation on the ocean floor temperature are estimated on the basis of diffusion models. It is shown that climatic variations with periods longer than one thousand years will be unattenuated and will affect the entire ocean floor. The perturbation method is used to study the effects of an irregular topography and a variable thickness of ocean floor sediments on the heat flow. Some special examples are given to provide a comparison between the perturbation solutions and exact solutions of similar problems. The perturbation method is also applied to a buried body with different thermal conductivity from its surroundings and the reliability of the perturbation solution is examined. Heat flow anomalies due to heat transport by magma intruded into crustal layers is studied by solving the heat conduction equation. It is shown that magmatic intrusions can lead to very large surface heat flow anomalies. Finally, the possibility of deriving the ocean floor thermal gradient on the basis of on-ship measurements performed on sediment cores is investigated. The results appear positive. The temperature variations in flowing wells and the temperature variation in a cylindrical sediment core influenced by the movement of water along the axis of the core are also studied. Close

• 514. [Article] Diffusion of oxygen and carbon dioxide through soil with temperature and water content effects on sink/source strength

  Gaseous diffusion equations which describe the diffusion of oxygen and carbon dioxide through soil have been studied by several investigators. However, these efforts seldom considered gaseous diffusion ...

  Citation × Citation Citation Abstract Copy Title: Diffusion of oxygen and carbon dioxide through soil with temperature and water content effects on sink/source strength Author: Ying, Ouyang Gaseous diffusion equations which describe the diffusion of oxygen and carbon dioxide through soil have been studied by several investigators. However, these efforts seldom considered gaseous diffusion through soil together with the effects of soil environmental factors such as soil temperature and soil water content on sink or source strength. Three gaseous diffusion equations have been formulated and solved. The problems considered are: (1) diffusion through a soil profile for conditions where the sink strength varies with temperature and is constant with time; (2) diffusion through a soil profile for conditions where the source strength varies with water content and temperature but is constant with time; (3) diffusion through a soil profile for conditions where the sink strength varies with time. The choices of mathematical representations of sink or source terms in the three equations are based on experiments reported in the literature by several authors. These sink or source models provide approximations of the relationships between the respiration activities of plant roots or soil microorganisms and the soil conditions such as temperature and water content. The new formulation for the effects of the soil temperature and soil water content on the diffusion coefficient was developed. Finite difference methods (Crank-Nicolson method) were used to solve the diffusion equations. Solutions obtained by solving the diffusion equations for three different environmental settings illustrate that soil temperature and water content have a strong effect on gaseous diffusion through the soil by controlling the sink or source strength. Results point to the need for better knowledge of the response of biological organisms in the soil to changing environmental conditions. Title: Diffusion of oxygen and carbon dioxide through soil with temperature and water content effects on sink/source strength Author: Ying, Ouyang Gaseous diffusion equations which describe the diffusion of oxygen and carbon dioxide through soil have been studied by several investigators. However, these efforts seldom considered gaseous diffusion through soil together with the effects of soil environmental factors such as soil temperature and soil water content on sink or source strength. Three gaseous diffusion equations have been formulated and solved. The problems considered are: (1) diffusion through a soil profile for conditions where the sink strength varies with temperature and is constant with time; (2) diffusion through a soil profile for conditions where the source strength varies with water content and temperature but is constant with time; (3) diffusion through a soil profile for conditions where the sink strength varies with time. The choices of mathematical representations of sink or source terms in the three equations are based on experiments reported in the literature by several authors. These sink or source models provide approximations of the relationships between the respiration activities of plant roots or soil microorganisms and the soil conditions such as temperature and water content. The new formulation for the effects of the soil temperature and soil water content on the diffusion coefficient was developed. Finite difference methods (Crank-Nicolson method) were used to solve the diffusion equations. Solutions obtained by solving the diffusion equations for three different environmental settings illustrate that soil temperature and water content have a strong effect on gaseous diffusion through the soil by controlling the sink or source strength. Results point to the need for better knowledge of the response of biological organisms in the soil to changing environmental conditions. Close

• 515. [Article] Scaling study of the depressurized conduction cooldown event in the high temperature test facility using RELAP5-3D/ATHENA

  In 2008, the Department of Energy (DOE) and Nuclear Regulatory Commission (NCR) decided that the Next Generation Nuclear Plant (NGNP) would be the Very High Temperature Reactor (VHTR). In support of the ...

  Citation × Citation Citation Abstract Copy Title: Scaling study of the depressurized conduction cooldown event in the high temperature test facility using RELAP5-3D/ATHENA Author: Aldridge, Robert J. In 2008, the Department of Energy (DOE) and Nuclear Regulatory Commission (NCR) decided that the Next Generation Nuclear Plant (NGNP) would be the Very High Temperature Reactor (VHTR). In support of the licensing and validation effort of the VHTR, Oregon State University was tasked with designing, building, and operating a thermal hydraulic test facility, the High Temperature Test Facility (HTTF). It is expected that the HTTF will provide data on the systemic response of the Modular High Temperature Gas Reactor (MHTGR) during the Depressurized Conduction Cooldown (DCC) event to validate safety analysis codes and the safety concept of the VHTR. The objective of this thesis was to determine the ability of the HTTF to model the DCC event compared to the MHTGR. To do this, a thermal hydraulic systems code, RELAP5-3D/ATHENA, was used to compare the systemic response of the MHTGR and HTTF during the DCC event. Two phases of the DCC event were modeled, the molecular diffusion phase and natural circulation phase. Each phase was modeled as a Separate Effects Test (SET) and as an Integral Effects Test (IET). For each test, the radial temperature profile, peak fuel temperature as a function of time, time to peak fuel temperature, air front velocity, time to onset of natural circulation, and natural circulation flow rates were compared to the MHTGR response. This thesis also provides an analysis of the scaling distortions inherent to the HTTF. Title: Scaling study of the depressurized conduction cooldown event in the high temperature test facility using RELAP5-3D/ATHENA Author: Aldridge, Robert J. In 2008, the Department of Energy (DOE) and Nuclear Regulatory Commission (NCR) decided that the Next Generation Nuclear Plant (NGNP) would be the Very High Temperature Reactor (VHTR). In support of the licensing and validation effort of the VHTR, Oregon State University was tasked with designing, building, and operating a thermal hydraulic test facility, the High Temperature Test Facility (HTTF). It is expected that the HTTF will provide data on the systemic response of the Modular High Temperature Gas Reactor (MHTGR) during the Depressurized Conduction Cooldown (DCC) event to validate safety analysis codes and the safety concept of the VHTR. The objective of this thesis was to determine the ability of the HTTF to model the DCC event compared to the MHTGR. To do this, a thermal hydraulic systems code, RELAP5-3D/ATHENA, was used to compare the systemic response of the MHTGR and HTTF during the DCC event. Two phases of the DCC event were modeled, the molecular diffusion phase and natural circulation phase. Each phase was modeled as a Separate Effects Test (SET) and as an Integral Effects Test (IET). For each test, the radial temperature profile, peak fuel temperature as a function of time, time to peak fuel temperature, air front velocity, time to onset of natural circulation, and natural circulation flow rates were compared to the MHTGR response. This thesis also provides an analysis of the scaling distortions inherent to the HTTF. Close

• 516. [Article] Low temperature deformation characteristics of yttrium single crystals

  First order prism slip in yttrium single crystals containing a total interstitial impurity content of about 200 wt ppm is almost entirely stage II deformation with a work hardening rate θ/μ of 2·10⁻ ³ ...

  Citation × Citation Citation Abstract Copy Title: Low temperature deformation characteristics of yttrium single crystals Author: Sokaski, Michael First order prism slip in yttrium single crystals containing a total interstitial impurity content of about 200 wt ppm is almost entirely stage II deformation with a work hardening rate θ/μ of 2·10⁻ ³ . The athermal temperature is about 300°K. Below this temperature an interstitial mechanism is rate controlling for dislocations moving on the first order prism planes. The obstacle energy is 0.31 eV and is substantially independent of temperature. The oxygen impurity does not influence the thermal component of the flow stress, although the athermal component increases with oxygen content. Above 300°K an intersection mechanism controls dislocation movement. Second order pyramidal slip is also almost entirely stage II deformation, but the work hardening rate is 10·10 ⁻³ . The critical resolved shear stress for second order pyramidal slip is about two times higher than for first order prism slip. The athermal temperature is approximately 300°K. Fleischer's criteria supporting an interstitial mechanism as rate controlling for dislocations moving on the second order pyramidal planes are satisfied in the entire temperature range that was investigated, i.e. 77°K to 297°K. The obstacle energy is 0.54 eV at the athermal temperature. However, the Dorn-Rajnak model supporting a Peierls mechanism is satisfied below 165°K, thus this mechanism could be rate controlling below 165°K. Second order pyramidal slip is active when the tensile axis is less than 37 degrees from the C-axis at 300°K. First order prism slip is active at all other orientations. Basal slip could not be activated at any orientation. Title: Low temperature deformation characteristics of yttrium single crystals Author: Sokaski, Michael First order prism slip in yttrium single crystals containing a total interstitial impurity content of about 200 wt ppm is almost entirely stage II deformation with a work hardening rate θ/μ of 2·10⁻ ³ . The athermal temperature is about 300°K. Below this temperature an interstitial mechanism is rate controlling for dislocations moving on the first order prism planes. The obstacle energy is 0.31 eV and is substantially independent of temperature. The oxygen impurity does not influence the thermal component of the flow stress, although the athermal component increases with oxygen content. Above 300°K an intersection mechanism controls dislocation movement. Second order pyramidal slip is also almost entirely stage II deformation, but the work hardening rate is 10·10 ⁻³ . The critical resolved shear stress for second order pyramidal slip is about two times higher than for first order prism slip. The athermal temperature is approximately 300°K. Fleischer's criteria supporting an interstitial mechanism as rate controlling for dislocations moving on the second order pyramidal planes are satisfied in the entire temperature range that was investigated, i.e. 77°K to 297°K. The obstacle energy is 0.54 eV at the athermal temperature. However, the Dorn-Rajnak model supporting a Peierls mechanism is satisfied below 165°K, thus this mechanism could be rate controlling below 165°K. Second order pyramidal slip is active when the tensile axis is less than 37 degrees from the C-axis at 300°K. First order prism slip is active at all other orientations. Basal slip could not be activated at any orientation. Close

• 517. [Article] Thermodynamic analysis of geothermal energy systems with forced recovery from aquifers

  A thermodynamic analysis of forced geoheat recovery from aquifers has been accomplished. The system investigated consists of a single recharging-discharging well pair, in a horizontally extensive aquifer, with ...

  Citation × Citation Citation Abstract Copy Title: Thermodynamic analysis of geothermal energy systems with forced recovery from aquifers Author: Lee, Se Kyoun A thermodynamic analysis of forced geoheat recovery from aquifers has been accomplished. The system investigated consists of a single recharging-discharging well pair, in a horizontally extensive aquifer, with either power generation or space heating as surface applications. The space heating systems investigated are (i)direct heating, (ii)heat pumps and (iii)a combination of direct heating and heat pumps. The thermodynamic performance parameters considered are the effectiveness (Second Law Efficiency) and fossil fuel savings. Previous work on this problem has considered only the surface system with a specified temperature at the wellhead. Also, in the previous work, the surface system was either power generation only or heating only. This thesis includes the subsurface system in the analysis and the surface application of this work is treated as an important parameter. Due to the interaction between the surface and subsurface systems, the load conditions and geologic conditions play important roles in determining the optimum operation. The analysis indicates that the well separation should be large enough to insure a constant production temperature during the project life time. For high temperature resources(higher than about 435 K), power generation yields the best performance and is therefore recommended. The relative desirability of the combination (heating and heat pumps) requires consideration of the load condition, resource temperature and other geologic conditions. Such evaluations for these automatically determine the appropriate ranges of direct heating. The optimum operation of each system is also dependent on the same parameters as well as the injection temperature. Analysis also has been done on a given well system with a small well separation. In such a case, operation must be continued after thermal breakthrough in order to obtain a moderate output for the life of the system. Power generation and the combination do not have good performance with this model. Direct heating, with careful control of flow rate, appears to be the preferred system. For low temperature resources, heat pumps can only be used with careful control of the flow rate and injection temperature. Title: Thermodynamic analysis of geothermal energy systems with forced recovery from aquifers Author: Lee, Se Kyoun A thermodynamic analysis of forced geoheat recovery from aquifers has been accomplished. The system investigated consists of a single recharging-discharging well pair, in a horizontally extensive aquifer, with either power generation or space heating as surface applications. The space heating systems investigated are (i)direct heating, (ii)heat pumps and (iii)a combination of direct heating and heat pumps. The thermodynamic performance parameters considered are the effectiveness (Second Law Efficiency) and fossil fuel savings. Previous work on this problem has considered only the surface system with a specified temperature at the wellhead. Also, in the previous work, the surface system was either power generation only or heating only. This thesis includes the subsurface system in the analysis and the surface application of this work is treated as an important parameter. Due to the interaction between the surface and subsurface systems, the load conditions and geologic conditions play important roles in determining the optimum operation. The analysis indicates that the well separation should be large enough to insure a constant production temperature during the project life time. For high temperature resources(higher than about 435 K), power generation yields the best performance and is therefore recommended. The relative desirability of the combination (heating and heat pumps) requires consideration of the load condition, resource temperature and other geologic conditions. Such evaluations for these automatically determine the appropriate ranges of direct heating. The optimum operation of each system is also dependent on the same parameters as well as the injection temperature. Analysis also has been done on a given well system with a small well separation. In such a case, operation must be continued after thermal breakthrough in order to obtain a moderate output for the life of the system. Power generation and the combination do not have good performance with this model. Direct heating, with careful control of flow rate, appears to be the preferred system. For low temperature resources, heat pumps can only be used with careful control of the flow rate and injection temperature. Close

• 518. [Article] Lasers in the Sky : Distributed Temperature Sensing and a Micro-Meteorological Approach to Quantifying Evapotranspiration

  Lower atmospheric flux measurements are a difficult subset of atmospheric data to accurately collect. The interplay of cost, precision, specialty, resolution and repeatability compound an already difficult ...

  Citation × Citation Citation Abstract Copy Title: Lasers in the Sky : Distributed Temperature Sensing and a Micro-Meteorological Approach to Quantifying Evapotranspiration Author: Predosa, Robert Lower atmospheric flux measurements are a difficult subset of atmospheric data to accurately collect. The interplay of cost, precision, specialty, resolution and repeatability compound an already difficult experimental problem. In response to this, a new, novel instrumentation approach to measuring within the atmospheric boundary layer (ABL) is introduced. The combination of Unmanned Aerial Vehicles (UAVs) and Distributed Temperature Sensing (DTS) technology are an unlikely pairing that show great potential for providing unprecedented levels of spatial and temporal resolution of the natural world. This pairing was deployed to the Oxbow Conservation Area near Bates, OR in July 2015 to measure vertically stratified temperature profiles. Additional modifications to the fiber optic cables were done in order to replicate the sling psychrometer approach to measuring humidity values by replicating a ‘dry’ and ‘wet’ bulb thermometer capable of measuring temperature gradients at high spatial and temporal resolutions. Out of 23 UAV flights conducted, thirteen provided usable data. Measurements and calculations were compared to a co-located Open Path Gas Analyzer and Sonic Anemometer (Irgason) for accuracy and precision. Four flights showed strong correlation to Eddy-Covariance calculations on sensible heat and evaporative flux. Moreso, the modified DTS field deployment provided new insights into stratified heterogeneities in vapor pressure, temperature, sensible heat, evaporative flux and temperature variance. Title: Lasers in the Sky : Distributed Temperature Sensing and a Micro-Meteorological Approach to Quantifying Evapotranspiration Author: Predosa, Robert Lower atmospheric flux measurements are a difficult subset of atmospheric data to accurately collect. The interplay of cost, precision, specialty, resolution and repeatability compound an already difficult experimental problem. In response to this, a new, novel instrumentation approach to measuring within the atmospheric boundary layer (ABL) is introduced. The combination of Unmanned Aerial Vehicles (UAVs) and Distributed Temperature Sensing (DTS) technology are an unlikely pairing that show great potential for providing unprecedented levels of spatial and temporal resolution of the natural world. This pairing was deployed to the Oxbow Conservation Area near Bates, OR in July 2015 to measure vertically stratified temperature profiles. Additional modifications to the fiber optic cables were done in order to replicate the sling psychrometer approach to measuring humidity values by replicating a ‘dry’ and ‘wet’ bulb thermometer capable of measuring temperature gradients at high spatial and temporal resolutions. Out of 23 UAV flights conducted, thirteen provided usable data. Measurements and calculations were compared to a co-located Open Path Gas Analyzer and Sonic Anemometer (Irgason) for accuracy and precision. Four flights showed strong correlation to Eddy-Covariance calculations on sensible heat and evaporative flux. Moreso, the modified DTS field deployment provided new insights into stratified heterogeneities in vapor pressure, temperature, sensible heat, evaporative flux and temperature variance. Close

• 519. [Article] Rainfall seasonality and an ecohydrological feedback offset the potential impact of climate warming on evapotranspiration and groundwater recharge

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291944-7973.

  Citation × Citation Citation Abstract Copy Title: Rainfall seasonality and an ecohydrological feedback offset the potential impact of climate warming on evapotranspiration and groundwater recharge Author: McDonnell, Jeffrey J., Pangle, Luke A., Gregg, Jillian W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291944-7973. Title: Rainfall seasonality and an ecohydrological feedback offset the potential impact of climate warming on evapotranspiration and groundwater recharge Author: McDonnell, Jeffrey J., Pangle, Luke A., Gregg, Jillian W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291944-7973. Close

• 520. [Article] The influence of certain environmental and edaphic factors on germination and emergence of Bromus tectorum L.

  The influence of certain environmental and edaphic factors on the germination and emergence of downy brome (Bromus tectorum L.) was investigated in the laboratory. A preliminary study was conducted to ...

  Citation × Citation Citation Abstract Copy Title: The influence of certain environmental and edaphic factors on germination and emergence of Bromus tectorum L. Author: Thill, Donald Cecil, 1950- The influence of certain environmental and edaphic factors on the germination and emergence of downy brome (Bromus tectorum L.) was investigated in the laboratory. A preliminary study was conducted to determine the osmotic stability of mannitol and polyethylene glycol 20,000 (PEG) solutions, which are commonly used to simulate water stress in seed germination studies, and to compare osmotic versus matric potential effects on the germination of winter wheat (Triticum aestivum L.). Lacking a weed seed source of known genetic uniformity and high percentage germination, wheat, which has both of these traits, was used as the test plant. Solutions of mannitol, PEG, and KCL (standard), with water potentials ranging from -3.5 to -18.0 bars, were incubated at 10, 20, and 30 C and analyzed periodically for water potential using thermocouple psychrometry. In addition, percentage and rate of germination of wheat seeds placed in moist soil or in 27-day-old or freshly prepared solutions of mannitol and PEG were compared. The osmotic potential of the different mannitol solutions and the -9.1 and -17.4 bar PEG solutions did not change with time. However, the osmotic potential of the -4.0 and -6.4 bar PEG solutions decreased about 1.0 bar. Percentage and rate of germination of winter wheat was the same in the 27-day-old and freshly prepared mannitol and PEG solutions; but at equal potentials, the germination rate was most rapid in the mannitol solutions. Wheat emergence rate from watered soil was linearly related to germination rate in PEG, but not mannitol solutions. Hence, the slight instability of PEG solutions appears to be of no biological consequence in seed germination studies. The interactive influence of soil matric potential and temperature on the percentage of downy brome seedling emergence was determined using soil ranging in matric potentials from -2 to -16 bars, and incubated at alternating and constant mean temperatures from 5.1 to 20 C. The interactive effects of soil bulk density, ranging from 0.9 to 1.3 g cm⁻³, and soil matric potentials, from -2 to -13 bars, on the percentage of seedling emergence was also examined. Reductions in soil matric potential markedly reduced the percentage of emergence. Overall, emergence was better at constant than at alternating temperatures. At higher matric potentials, downy brome emerged faster at warmer temperatures, while at very low matric potentials the percentage of seedling emergence was least restricted at cooler temperatures. Cold soil temperatures markedly reduced emergence at all levels of soil moisture. Soil matric potentials did not affect the percentage of emergence of seedlings grown from seed lots harvested during climatologically diverse years. Emergence, but not germination, was inhibited by increased levels of soil compaction. No significant soil compaction x moisture interaction was observed as measured by final seedling emergence. Under rangeland and wasteland conditions, the successful seedling establishment of downy brome is probably most limited by warm, dry soils or very cold soils (subzero temperatures for part of the day). All other moisture-temperature conditions appear intermediate to these two extremes in effect on establishment. Under cultivated field conditions soil compaction appears to be the major factor controlling successful seedling establishment. The effect of high-temperature on overcoming initial postharvest dormancy, and the possible occurrence of natural endogenous germination rhythms in downy brome seeds were investigated. Afterripening temperatures from 0 to 50 C, for periods of 0 to 28 days, had little effect on downy brome germination in petri dishes at 15 and 20 C incubation temperature. However, at 30 C germination temperature, the percentage of germination was significantly increased by short periods of afterripening at 50 C. Similar results occurred at 20 to 40 C afterripening after 14 to 28 days exposure. In general, high-temperature afterripening conditions (40 to 50 C) initially increased downy brome germination at 30 C incubation temperature, with prolonged exposure tending to decrease germination. No endogenously controlled germination rhythms were observed in downy brome seeds. Title: The influence of certain environmental and edaphic factors on germination and emergence of Bromus tectorum L. Author: Thill, Donald Cecil, 1950- The influence of certain environmental and edaphic factors on the germination and emergence of downy brome (Bromus tectorum L.) was investigated in the laboratory. A preliminary study was conducted to determine the osmotic stability of mannitol and polyethylene glycol 20,000 (PEG) solutions, which are commonly used to simulate water stress in seed germination studies, and to compare osmotic versus matric potential effects on the germination of winter wheat (Triticum aestivum L.). Lacking a weed seed source of known genetic uniformity and high percentage germination, wheat, which has both of these traits, was used as the test plant. Solutions of mannitol, PEG, and KCL (standard), with water potentials ranging from -3.5 to -18.0 bars, were incubated at 10, 20, and 30 C and analyzed periodically for water potential using thermocouple psychrometry. In addition, percentage and rate of germination of wheat seeds placed in moist soil or in 27-day-old or freshly prepared solutions of mannitol and PEG were compared. The osmotic potential of the different mannitol solutions and the -9.1 and -17.4 bar PEG solutions did not change with time. However, the osmotic potential of the -4.0 and -6.4 bar PEG solutions decreased about 1.0 bar. Percentage and rate of germination of winter wheat was the same in the 27-day-old and freshly prepared mannitol and PEG solutions; but at equal potentials, the germination rate was most rapid in the mannitol solutions. Wheat emergence rate from watered soil was linearly related to germination rate in PEG, but not mannitol solutions. Hence, the slight instability of PEG solutions appears to be of no biological consequence in seed germination studies. The interactive influence of soil matric potential and temperature on the percentage of downy brome seedling emergence was determined using soil ranging in matric potentials from -2 to -16 bars, and incubated at alternating and constant mean temperatures from 5.1 to 20 C. The interactive effects of soil bulk density, ranging from 0.9 to 1.3 g cm⁻³, and soil matric potentials, from -2 to -13 bars, on the percentage of seedling emergence was also examined. Reductions in soil matric potential markedly reduced the percentage of emergence. Overall, emergence was better at constant than at alternating temperatures. At higher matric potentials, downy brome emerged faster at warmer temperatures, while at very low matric potentials the percentage of seedling emergence was least restricted at cooler temperatures. Cold soil temperatures markedly reduced emergence at all levels of soil moisture. Soil matric potentials did not affect the percentage of emergence of seedlings grown from seed lots harvested during climatologically diverse years. Emergence, but not germination, was inhibited by increased levels of soil compaction. No significant soil compaction x moisture interaction was observed as measured by final seedling emergence. Under rangeland and wasteland conditions, the successful seedling establishment of downy brome is probably most limited by warm, dry soils or very cold soils (subzero temperatures for part of the day). All other moisture-temperature conditions appear intermediate to these two extremes in effect on establishment. Under cultivated field conditions soil compaction appears to be the major factor controlling successful seedling establishment. The effect of high-temperature on overcoming initial postharvest dormancy, and the possible occurrence of natural endogenous germination rhythms in downy brome seeds were investigated. Afterripening temperatures from 0 to 50 C, for periods of 0 to 28 days, had little effect on downy brome germination in petri dishes at 15 and 20 C incubation temperature. However, at 30 C germination temperature, the percentage of germination was significantly increased by short periods of afterripening at 50 C. Similar results occurred at 20 to 40 C afterripening after 14 to 28 days exposure. In general, high-temperature afterripening conditions (40 to 50 C) initially increased downy brome germination at 30 C incubation temperature, with prolonged exposure tending to decrease germination. No endogenously controlled germination rhythms were observed in downy brome seeds. Close