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• 31. [Article] Long-Term Stability of 14YT-4Sc Alloy at High Temperature

  14YT alloy (Fe-14Cr-0.25wt.%Y2O3-0.4wt.%Ti) with 4 at.% Sc addition was previously reported to exhibit a nanoscale microstructure and high strength when annealed at temperatures up to 1000 °C (0.65Tm) ...

  Citation × Citation Citation Abstract Copy Title: Long-Term Stability of 14YT-4Sc Alloy at High Temperature Author: Li, Lulu, Xu, Weizong, Saber, Mostafa, Zhu, Yuntian, Koch, Carl C., Scattergood, Ronald O. Year: 2015 14YT alloy (Fe-14Cr-0.25wt.%Y2O3-0.4wt.%Ti) with 4 at.% Sc addition was previously reported to exhibit a nanoscale microstructure and high strength when annealed at temperatures up to 1000 °C (0.65Tm) for 1 hour. Here we report that the microstructure and mechanical behavior of 14YT-4Sc alloy after long-term annealing for up to 60 hours at 1000 °C. FIB analysis shows abnormal grain growth with annealing time, while a large fraction of the matrix still consists of nanoscale grains. TEM images reveal a slight growth of nano grains, with estimated grain growth exponent, n, to be 0.29. Sc-Ti-Y-O enriched nano oxide particles (nm) were observed in EDS mapping of the 14YT-4Sc-60h sample. The nano-structure retention at the high temperature of 1000 °C for 60 hours is attributed to these complex nano oxides. Title: Long-Term Stability of 14YT-4Sc Alloy at High Temperature Author: Li, Lulu, Xu, Weizong, Saber, Mostafa, Zhu, Yuntian, Koch, Carl C., Scattergood, Ronald O. Year: 2015 14YT alloy (Fe-14Cr-0.25wt.%Y2O3-0.4wt.%Ti) with 4 at.% Sc addition was previously reported to exhibit a nanoscale microstructure and high strength when annealed at temperatures up to 1000 °C (0.65Tm) for 1 hour. Here we report that the microstructure and mechanical behavior of 14YT-4Sc alloy after long-term annealing for up to 60 hours at 1000 °C. FIB analysis shows abnormal grain growth with annealing time, while a large fraction of the matrix still consists of nanoscale grains. TEM images reveal a slight growth of nano grains, with estimated grain growth exponent, n, to be 0.29. Sc-Ti-Y-O enriched nano oxide particles (nm) were observed in EDS mapping of the 14YT-4Sc-60h sample. The nano-structure retention at the high temperature of 1000 °C for 60 hours is attributed to these complex nano oxides. Close

• 32. [Article] Influence of Scandium Addition on the High-Temperature Grain Size Stabilization of Oxide-Dispersion-Strengthened (ODS) Ferritic Alloy

  The influence of 1–4 at% Sc addition on the thermal stability of mechanically alloyed ODS ferritic alloy was studied in this work. Sc addition was found to significantly stabilize grain size and microhardness ...

  Citation × Citation Citation Abstract Copy Title: Influence of Scandium Addition on the High-Temperature Grain Size Stabilization of Oxide-Dispersion-Strengthened (ODS) Ferritic Alloy Author: Li, Lulu, Xu, Weizong, Saber, Mostafa, Zhu, Yuntian, Koch, Carl C., Scattergood, Ronald O. Year: 2015 The influence of 1–4 at% Sc addition on the thermal stability of mechanically alloyed ODS ferritic alloy was studied in this work. Sc addition was found to significantly stabilize grain size and microhardness at high temperatures. Grain sizes of samples with 1 and 4 at% Sc was found maintained in the nanoscale range at temperatures up to 1000 °C with hardness maintained at 5.6 and 6.7 GPa, respectively. The detailed microstructure was also investigated from EDS elemental mapping, where nanofeatures [ScTiO] were observed, while nanosized [YTiO] particles were rarely seen. This is probably due to the concentration difference between Sc and Y, leading to the formation of [ScTiO] favoring that of [YTiO]. Precipitation was considered as the major source for the observed high temperature stabilization. In addition, 14YT–Sc alloys without large second phases such as Ti-oxide can exhibit better performance compared to conventional ODS materials. Title: Influence of Scandium Addition on the High-Temperature Grain Size Stabilization of Oxide-Dispersion-Strengthened (ODS) Ferritic Alloy Author: Li, Lulu, Xu, Weizong, Saber, Mostafa, Zhu, Yuntian, Koch, Carl C., Scattergood, Ronald O. Year: 2015 The influence of 1–4 at% Sc addition on the thermal stability of mechanically alloyed ODS ferritic alloy was studied in this work. Sc addition was found to significantly stabilize grain size and microhardness at high temperatures. Grain sizes of samples with 1 and 4 at% Sc was found maintained in the nanoscale range at temperatures up to 1000 °C with hardness maintained at 5.6 and 6.7 GPa, respectively. The detailed microstructure was also investigated from EDS elemental mapping, where nanofeatures [ScTiO] were observed, while nanosized [YTiO] particles were rarely seen. This is probably due to the concentration difference between Sc and Y, leading to the formation of [ScTiO] favoring that of [YTiO]. Precipitation was considered as the major source for the observed high temperature stabilization. In addition, 14YT–Sc alloys without large second phases such as Ti-oxide can exhibit better performance compared to conventional ODS materials. Close

• 33. [Article] Mixing Times of Organic Molecules Within Secondary Organic Aerosol Particles: A Global Planetary Boundary Layer Perspective

  When simulating the formation and life cycle of secondary organic aerosol (SOA) with chemical transport models, it is often assumed that organic molecules are well mixed within SOA particles on the timescale ...

  Citation × Citation Citation Abstract Copy Title: Mixing Times of Organic Molecules Within Secondary Organic Aerosol Particles: A Global Planetary Boundary Layer Perspective Author: Maclean, Adrian M., Butenhoff, Christopher L., Grayson, James W., Barsanti, Kelley, Jimenez, Jose L., Bertram, Allan K. Year: 2017 When simulating the formation and life cycle of secondary organic aerosol (SOA) with chemical transport models, it is often assumed that organic molecules are well mixed within SOA particles on the timescale of 1 h. While this assumption has been debated vigorously in the literature, the issue remains unresolved in part due to a lack of information on the mixing times within SOA particles as a function of both temperature and relative humidity. Using laboratory data, meteorological fields, and a chemical transport model, we estimated how often mixing times are < 1 h within SOA in the planetary boundary layer (PBL), the region of the atmosphere where SOA concentrations are on average the highest. First, a parameterization for viscosity as a function of temperature and RH was developed for α-pinene SOA using room-temperature and low-temperature viscosity data for α-pinene SOA generated in the laboratory using mass concentrations of ∼ 1000 µg m−3. Based on this parameterization, the mixing times within α-pinene SOA are < 1 h for 98.5 % and 99.9 % of the occurrences in the PBL during January and July, respectively, when concentrations are significant (total organic aerosol concentrations are > 0.5 µg m−3 at the surface). Next, as a starting point to quantify how often mixing times of organic molecules are < 1 h within α-pinene SOA generated using low, atmospherically relevant mass concentrations, we developed a temperature independent parameterization for viscosity using the room temperature viscosity data for α-pinene SOA generated in the laboratory using a mass concentration of ~70 μg m-3. Based on this temperature-independent parameterization, mixing times within α-pinene SOA are < 1 h for 27 and 19.5% of the occurrences in the PBL during January and July, respectively, when concentrations are significant. However, associated with these conclusions are several caveats, and due to these caveats we are unable to make strong conclusions about how often mixing times of organic molecules are < 1 h within pinene SOA generated using low, atmospherically relevant mass concentrations. Finally, a parameterization for viscosity of anthropogenic SOA as a function of temperature and RH was developed using sucrose–water data. Based on this parameterization, and assuming sucrose is a good proxy for anthropogenic SOA, 70 and 83% of the mixing times within anthropogenic SOA in the PBL are < 1 h for January and July, respectively, when concentrations are significant. These percentages are likely lower limits due to the assumptions used to calculate mixing times. Title: Mixing Times of Organic Molecules Within Secondary Organic Aerosol Particles: A Global Planetary Boundary Layer Perspective Author: Maclean, Adrian M., Butenhoff, Christopher L., Grayson, James W., Barsanti, Kelley, Jimenez, Jose L., Bertram, Allan K. Year: 2017 When simulating the formation and life cycle of secondary organic aerosol (SOA) with chemical transport models, it is often assumed that organic molecules are well mixed within SOA particles on the timescale of 1 h. While this assumption has been debated vigorously in the literature, the issue remains unresolved in part due to a lack of information on the mixing times within SOA particles as a function of both temperature and relative humidity. Using laboratory data, meteorological fields, and a chemical transport model, we estimated how often mixing times are < 1 h within SOA in the planetary boundary layer (PBL), the region of the atmosphere where SOA concentrations are on average the highest. First, a parameterization for viscosity as a function of temperature and RH was developed for α-pinene SOA using room-temperature and low-temperature viscosity data for α-pinene SOA generated in the laboratory using mass concentrations of ∼ 1000 µg m−3. Based on this parameterization, the mixing times within α-pinene SOA are < 1 h for 98.5 % and 99.9 % of the occurrences in the PBL during January and July, respectively, when concentrations are significant (total organic aerosol concentrations are > 0.5 µg m−3 at the surface). Next, as a starting point to quantify how often mixing times of organic molecules are < 1 h within α-pinene SOA generated using low, atmospherically relevant mass concentrations, we developed a temperature independent parameterization for viscosity using the room temperature viscosity data for α-pinene SOA generated in the laboratory using a mass concentration of ~70 μg m-3. Based on this temperature-independent parameterization, mixing times within α-pinene SOA are < 1 h for 27 and 19.5% of the occurrences in the PBL during January and July, respectively, when concentrations are significant. However, associated with these conclusions are several caveats, and due to these caveats we are unable to make strong conclusions about how often mixing times of organic molecules are < 1 h within pinene SOA generated using low, atmospherically relevant mass concentrations. Finally, a parameterization for viscosity of anthropogenic SOA as a function of temperature and RH was developed using sucrose–water data. Based on this parameterization, and assuming sucrose is a good proxy for anthropogenic SOA, 70 and 83% of the mixing times within anthropogenic SOA in the PBL are < 1 h for January and July, respectively, when concentrations are significant. These percentages are likely lower limits due to the assumptions used to calculate mixing times. Close

• 34. [Article] The Effect of Seasonal Temperature Changes on the Light-Use Efficiency of Two Coral Communities

  37 pages. A thesis presented to the Departments of Biology and Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor ...

  Citation × Citation Citation Abstract Copy Title: The Effect of Seasonal Temperature Changes on the Light-Use Efficiency of Two Coral Communities Author: Saraceno, Hannah McKenzie Year: 2017 37 pages. A thesis presented to the Departments of Biology and Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2017 Title: The Effect of Seasonal Temperature Changes on the Light-Use Efficiency of Two Coral Communities Author: Saraceno, Hannah McKenzie Year: 2017 37 pages. A thesis presented to the Departments of Biology and Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2017 Close

• 35. [Article] Hydrodynamic and Water Quality Modeling of the Chehalis River in Washington

  The Chehalis River Basin is located in the southwest region of Washington and is over 125 miles long flowing through agricultural, residential, industrial, and forest land. Four major rivers, many smaller ...

  Citation × Citation Citation Abstract Copy Title: Hydrodynamic and Water Quality Modeling of the Chehalis River in Washington Author: Van Glubt, Sarah, Wells, Scott A., Berger, Chris J. Year: 2017 The Chehalis River Basin is located in the southwest region of Washington and is over 125 miles long flowing through agricultural, residential, industrial, and forest land. Four major rivers, many smaller creeks, five wastewater treatment plants, and groundwater discharge to the Chehalis River. Flooding is a major problem in the relatively flat areas surrounding the cities of Chehalis and Centralia. As a result, construction of a flood-control dam in the upper basin has been proposed. One major concern of constructing a dam is the potentially severe impacts to fish health and habitat. The Chehalis River has routinely violated water quality standards for primarily temperature and dissolved oxygen. CE-QUAL-W2, a two-dimensional (longitudinal and vertical) hydrodynamic and water quality model, was used to simulate the Chehalis River, including free flowing river stretches and stratified (in summer) lake-like stretches. The goals of this research were to assess the flood retention structure’s impacts to water quality, as well as river responses to potential climate change scenarios. In order to use the model to achieve these goals, calibration to field data for flow, temperature, and water quality constituents was performed for the years 2013 and 2014. Once calibration was complete, model scenarios for future climate conditions and dam operating regimes were conducted. Future conditions showed predictions of warmer water temperatures and slight changes to water quality conditions on the river. As fish in the area prefer cooler water temperatures, this could pose a threat to fish health and habitat. Flood retention structures with the purpose of flood retention only (only operating during times of flooding) gave model predictions for daily maximum temperature higher than structures that employed flood retention and flow augmentation (operating during all times of the year). This suggested the management of flow passage or retention by the dam is important for water quality on the river. Title: Hydrodynamic and Water Quality Modeling of the Chehalis River in Washington Author: Van Glubt, Sarah, Wells, Scott A., Berger, Chris J. Year: 2017 The Chehalis River Basin is located in the southwest region of Washington and is over 125 miles long flowing through agricultural, residential, industrial, and forest land. Four major rivers, many smaller creeks, five wastewater treatment plants, and groundwater discharge to the Chehalis River. Flooding is a major problem in the relatively flat areas surrounding the cities of Chehalis and Centralia. As a result, construction of a flood-control dam in the upper basin has been proposed. One major concern of constructing a dam is the potentially severe impacts to fish health and habitat. The Chehalis River has routinely violated water quality standards for primarily temperature and dissolved oxygen. CE-QUAL-W2, a two-dimensional (longitudinal and vertical) hydrodynamic and water quality model, was used to simulate the Chehalis River, including free flowing river stretches and stratified (in summer) lake-like stretches. The goals of this research were to assess the flood retention structure’s impacts to water quality, as well as river responses to potential climate change scenarios. In order to use the model to achieve these goals, calibration to field data for flow, temperature, and water quality constituents was performed for the years 2013 and 2014. Once calibration was complete, model scenarios for future climate conditions and dam operating regimes were conducted. Future conditions showed predictions of warmer water temperatures and slight changes to water quality conditions on the river. As fish in the area prefer cooler water temperatures, this could pose a threat to fish health and habitat. Flood retention structures with the purpose of flood retention only (only operating during times of flooding) gave model predictions for daily maximum temperature higher than structures that employed flood retention and flow augmentation (operating during all times of the year). This suggested the management of flow passage or retention by the dam is important for water quality on the river. Close

• 36. [Article] Effect of Oxygen Content on Thermal Stability of Grain Size for Nanocrystalline Fe10Cr and Fe14Cr4Hf Alloy Powders

  Low oxygen content powders of high purity elemental Fe, Cr and Hf were produced in a glove box by mechanically filing the solid materials. Fe10Cr and Fe14Cr4Hf nanocrystalline alloy powders were processed ...

  Citation × Citation Citation Abstract Copy Title: Effect of Oxygen Content on Thermal Stability of Grain Size for Nanocrystalline Fe10Cr and Fe14Cr4Hf Alloy Powders Author: Roodposhti, Peiman Shahbeigi, Saber, Mostafa, Koch, Carl, Scattergood, Ronald Year: 2017 Low oxygen content powders of high purity elemental Fe, Cr and Hf were produced in a glove box by mechanically filing the solid materials. Fe10Cr and Fe14Cr4Hf nanocrystalline alloy powders were processed using these elemental powders in conjunction with SPEX ball milling. The grain-size stability of the nanocrystalline alloy powders was investigated for selected annealing temperatures. High temperature stabilization can be achieved by Zener pinning (kinetic mechanism) or segregation of Hf to grain boundaries (thermodynamic mechanism). Solute drag mechanisms can be effective at lower annealing temperatures. Recent regular solution models developed by the authors predict that Hf would facilitate thermodynamic grain-size stabilization in Fe14Cr4Hf alloys at high temperatures. However Hf-base reactions such as intermetallic phase or oxide formation can favor kinetic stabilization and this can dominate over a contribution from thermodynamic stabilization. In contrast, grain-size stabilization in Fe10Cr alloy would be a result of solute drag by the Cr solutes at lower temperatures. The results from previous investigations on Fe10Cr and Fe14Cr4Hf nanocrystalline alloys were (unknowingly at the time) influenced by the fact that the commercially available high purity elemental powders used for SPEX ball mill processing contained significant amounts of oxygen impurity. The results obtained in this investigation using identical processing methods with low oxygen content powders for synthesizing the alloys provide further insight into their stabilization mechanisms. Title: Effect of Oxygen Content on Thermal Stability of Grain Size for Nanocrystalline Fe10Cr and Fe14Cr4Hf Alloy Powders Author: Roodposhti, Peiman Shahbeigi, Saber, Mostafa, Koch, Carl, Scattergood, Ronald Year: 2017 Low oxygen content powders of high purity elemental Fe, Cr and Hf were produced in a glove box by mechanically filing the solid materials. Fe10Cr and Fe14Cr4Hf nanocrystalline alloy powders were processed using these elemental powders in conjunction with SPEX ball milling. The grain-size stability of the nanocrystalline alloy powders was investigated for selected annealing temperatures. High temperature stabilization can be achieved by Zener pinning (kinetic mechanism) or segregation of Hf to grain boundaries (thermodynamic mechanism). Solute drag mechanisms can be effective at lower annealing temperatures. Recent regular solution models developed by the authors predict that Hf would facilitate thermodynamic grain-size stabilization in Fe14Cr4Hf alloys at high temperatures. However Hf-base reactions such as intermetallic phase or oxide formation can favor kinetic stabilization and this can dominate over a contribution from thermodynamic stabilization. In contrast, grain-size stabilization in Fe10Cr alloy would be a result of solute drag by the Cr solutes at lower temperatures. The results from previous investigations on Fe10Cr and Fe14Cr4Hf nanocrystalline alloys were (unknowingly at the time) influenced by the fact that the commercially available high purity elemental powders used for SPEX ball mill processing contained significant amounts of oxygen impurity. The results obtained in this investigation using identical processing methods with low oxygen content powders for synthesizing the alloys provide further insight into their stabilization mechanisms. Close

• 37. [Article] Static Fatigue Lifetime of Optical Fibers Assessed Using Boltzmann-Arrhenius-Zhurkov (BAZ) Model

  The recently suggested probabilistic design-for-reliability (PDfR) concept and particularly its physically meaningful and flexible Boltzmann–Arrhenius–Zhurkov (BAZ) model, can be effectively employed as ...

  Citation × Citation Citation Abstract Copy Title: Static Fatigue Lifetime of Optical Fibers Assessed Using Boltzmann-Arrhenius-Zhurkov (BAZ) Model Author: Suhir, Ephraim Year: 2017 The recently suggested probabilistic design-for-reliability (PDfR) concept and particularly its physically meaningful and flexible Boltzmann–Arrhenius–Zhurkov (BAZ) model, can be effectively employed as an attractive replacement of the widely used today purely empirical and physically unsubstantiated power law relationship for assessing the static fatigue (delayed fracture) lifetime of optical silica fibers. In this analysis the BAZ model is employed to estimate the static fatigue lifetime of an optical silica fiber under the combined action of tensile loading and an elevated temperature. The PDfR concept has its experimental basis in the highly-focused and highly-cost-effective failure-oriented accelerated testing (FOAT). Accordingly, it is shown how the PDfR concept, BAZ model and FOAT data can be effectively used, when there is a need to assess the long-term tensile strength (static fatigue life) of a coated optical fiber subjected to the combined action of tensile loading and elevated temperature. Although the role of elevated humidity might be insignificant owing to the elevated temperature conditions, this role can be accounted for, if there is a need for that, as well, by using multi-parametric BAZ model. Since the principle of superposition does not work in reliability engineering, all the three stressors, namely, the elevated temperature, tensile stress and relative humidity, should be applied concurrently to the specimen under test, and their coupling, if any, should and could be considered by the FOAT based on the BAZ model. The numerical example is carried out, however, for the case when only the elevated temperature and tensile stress are applied. The results of the analysis can be employed in the design and testing of optical silica fibers. Title: Static Fatigue Lifetime of Optical Fibers Assessed Using Boltzmann-Arrhenius-Zhurkov (BAZ) Model Author: Suhir, Ephraim Year: 2017 The recently suggested probabilistic design-for-reliability (PDfR) concept and particularly its physically meaningful and flexible Boltzmann–Arrhenius–Zhurkov (BAZ) model, can be effectively employed as an attractive replacement of the widely used today purely empirical and physically unsubstantiated power law relationship for assessing the static fatigue (delayed fracture) lifetime of optical silica fibers. In this analysis the BAZ model is employed to estimate the static fatigue lifetime of an optical silica fiber under the combined action of tensile loading and an elevated temperature. The PDfR concept has its experimental basis in the highly-focused and highly-cost-effective failure-oriented accelerated testing (FOAT). Accordingly, it is shown how the PDfR concept, BAZ model and FOAT data can be effectively used, when there is a need to assess the long-term tensile strength (static fatigue life) of a coated optical fiber subjected to the combined action of tensile loading and elevated temperature. Although the role of elevated humidity might be insignificant owing to the elevated temperature conditions, this role can be accounted for, if there is a need for that, as well, by using multi-parametric BAZ model. Since the principle of superposition does not work in reliability engineering, all the three stressors, namely, the elevated temperature, tensile stress and relative humidity, should be applied concurrently to the specimen under test, and their coupling, if any, should and could be considered by the FOAT based on the BAZ model. The numerical example is carried out, however, for the case when only the elevated temperature and tensile stress are applied. The results of the analysis can be employed in the design and testing of optical silica fibers. Close

• 38. [Article] Development of a Steady-State River Hydrodynamic and Temperature Model Based on CE-QUAL-W2

  CE-QUAL-W2 is a 2-D hydrodynamic and water quality model that has been applied to reservoirs, lakes, river systems, and estuaries throughout the world. However, when this model is applied for shallow systems, ...

  Citation × Citation Citation Abstract Copy Title: Development of a Steady-State River Hydrodynamic and Temperature Model Based on CE-QUAL-W2 Author: Xu, Wenwei Year: 2014 CE-QUAL-W2 is a 2-D hydrodynamic and water quality model that has been applied to reservoirs, lakes, river systems, and estuaries throughout the world. However, when this model is applied for shallow systems, this model requires a long calculation time to maintain numerical stability, compared to applications of reservoirs or deeper river systems. To solve this problem, a new hydrodynamic and temperature model was built based on the framework of CE-QUAL-W2 but that allows for steady-state hydrodynamic computations. By calculating the hydrodynamics at steady-state, the time step for stability is relaxed and simulations can proceed at much higher time steps. The rest of the model framework is still used for water quality state variables, in this case, temperature. The algorithm used for computing the water surface elevation is Manning's equation. This thesis study is one part of the Willamette Water 2100 project (Santelmann et al., 2012), which examines hydrological, ecological, and human factors affecting water scarcity in the Willamette River Basin. This study included three stages: (1) Convert six existing CE-QUAL-W2 V3.1 models into a newer version: CE-QUAL-W2 V3.7. (2) Develop the steady-state model code in FORTRAN. (3) Test the steady-state model on three river systems in the Willamette River Basin at Year 2001 and 2002. The result proved that the steady-state model could reduce the computing time by 90% for river applications, while predicting dynamic river temperature with high accuracy at a two-minute time scale. This new model will be employed to simulate the future of the Willamette River System at a decadal or centennial timescales, addressing river temperature concerns and fish habitat issues. Title: Development of a Steady-State River Hydrodynamic and Temperature Model Based on CE-QUAL-W2 Author: Xu, Wenwei Year: 2014 CE-QUAL-W2 is a 2-D hydrodynamic and water quality model that has been applied to reservoirs, lakes, river systems, and estuaries throughout the world. However, when this model is applied for shallow systems, this model requires a long calculation time to maintain numerical stability, compared to applications of reservoirs or deeper river systems. To solve this problem, a new hydrodynamic and temperature model was built based on the framework of CE-QUAL-W2 but that allows for steady-state hydrodynamic computations. By calculating the hydrodynamics at steady-state, the time step for stability is relaxed and simulations can proceed at much higher time steps. The rest of the model framework is still used for water quality state variables, in this case, temperature. The algorithm used for computing the water surface elevation is Manning's equation. This thesis study is one part of the Willamette Water 2100 project (Santelmann et al., 2012), which examines hydrological, ecological, and human factors affecting water scarcity in the Willamette River Basin. This study included three stages: (1) Convert six existing CE-QUAL-W2 V3.1 models into a newer version: CE-QUAL-W2 V3.7. (2) Develop the steady-state model code in FORTRAN. (3) Test the steady-state model on three river systems in the Willamette River Basin at Year 2001 and 2002. The result proved that the steady-state model could reduce the computing time by 90% for river applications, while predicting dynamic river temperature with high accuracy at a two-minute time scale. This new model will be employed to simulate the future of the Willamette River System at a decadal or centennial timescales, addressing river temperature concerns and fish habitat issues. Close

• 39. [Article] Using Spatially Explicit Indicators to Investigate Watershed Characteristics and stream temperature relationships

  We generate a series of novel indicators of spatially explicit watershed permeability and runoff characteristics to examine the relationship between land cover and water temperature parameters in a rapidly ...

  Citation × Citation Citation Abstract Copy Title: Using Spatially Explicit Indicators to Investigate Watershed Characteristics and stream temperature relationships Author: Grabowski, Zbigniew J., Watson, Eric, Chang, Heejun Year: 2016 We generate a series of novel indicators of spatially explicit watershed permeability and runoff characteristics to examine the relationship between land cover and water temperature parameters in a rapidly urbanizing watershed. Our framework provides a readily adaptable method to examine the thermal sensitivity of streams based upon the underlying geomorphological and surface characteristics of drainage basins. Using four model groups each using a different landscape characteristic weighting scheme (Model Group 1: areal averages; Model Group 2: inverse distance by total flow length; Model Group 3: overland distance to stream network and distance squared; Model Group 4: proportional flow accumulation), we examined the predictive capacity of 19 variables, including combinations of simplified land cover, elevation, slope, and flow accumulation, on five stream thermal properties: seven day moving average of daily minimum and maximum, seasonal mean temperature, a novel metric of thermal 'flashiness', and total days with maximum temperature exceeding 17.8°C. We find that the use of spatially explicit landscape indicators combining watershed processes improves the performance of regressions for predicting a number of ecologically relevant stream temperature variables. Improved indicators of watershed condition lend themselves for rapid investigation of the relationship between stream thermal conditions and landscape characteristics in watersheds modified by human land uses, ultimately providing a more hydrologically meaningful indicator for the impacts of landscape change. Title: Using Spatially Explicit Indicators to Investigate Watershed Characteristics and stream temperature relationships Author: Grabowski, Zbigniew J., Watson, Eric, Chang, Heejun Year: 2016 We generate a series of novel indicators of spatially explicit watershed permeability and runoff characteristics to examine the relationship between land cover and water temperature parameters in a rapidly urbanizing watershed. Our framework provides a readily adaptable method to examine the thermal sensitivity of streams based upon the underlying geomorphological and surface characteristics of drainage basins. Using four model groups each using a different landscape characteristic weighting scheme (Model Group 1: areal averages; Model Group 2: inverse distance by total flow length; Model Group 3: overland distance to stream network and distance squared; Model Group 4: proportional flow accumulation), we examined the predictive capacity of 19 variables, including combinations of simplified land cover, elevation, slope, and flow accumulation, on five stream thermal properties: seven day moving average of daily minimum and maximum, seasonal mean temperature, a novel metric of thermal 'flashiness', and total days with maximum temperature exceeding 17.8°C. We find that the use of spatially explicit landscape indicators combining watershed processes improves the performance of regressions for predicting a number of ecologically relevant stream temperature variables. Improved indicators of watershed condition lend themselves for rapid investigation of the relationship between stream thermal conditions and landscape characteristics in watersheds modified by human land uses, ultimately providing a more hydrologically meaningful indicator for the impacts of landscape change. Close

• 40. [Article] Power core (PC) Embedding a Plurality of IC Devices and Sandwiched Between Two Dissimilar Insulated Metal Substrates (IMS’): Predicted Thermal Stresses

  Power core (PC) sandwiched between two insulated metal substrates (IMS) and embedding active and passive integrated circuit (IC) devices is currently viewed as an attractive advanced packaging option having ...

  Citation × Citation Citation Abstract Copy Title: Power core (PC) Embedding a Plurality of IC Devices and Sandwiched Between Two Dissimilar Insulated Metal Substrates (IMS’): Predicted Thermal Stresses Author: Suhir, Ephraim, Nicolics, Johann Year: 2016 Power core (PC) sandwiched between two insulated metal substrates (IMS) and embedding active and passive integrated circuit (IC) devices is currently viewed as an attractive advanced packaging option having a strong potential in the automotive industry and beyond. A natural reliability concern, however, is the level of the thermally induced stresses in a tri-material assembly of the type in question. Accordingly, an analytical (mathematical) stress model is developed for the evaluation of these stresses. The stresses include normal stresses acting in the cross-sections of the assembly components, and the interfacial shearing and peeling stresses acting at the interfaces of these components and at the interfaces of the embedded IC devices. The model can be helpful in the stress-analysis and physical design of the assemblies, in which the PC is sandwiched between two IMS’. It can be used also in other areas of engineering, where tri-material assemblies comprised of dissimilar materials and subjected to the change in temperature are employed. The general concepts are illustrated by a detailed numerical example. The analysis is an extension of the study carried out earlier for a bow-free assembly. It is noteworthy that although the calculations are carried out for the case when the assembly is cooled down from an elevated temperature to a low temperature, since a linear approach is used and the stresses are proportional to the change in temperature, whatever its sign or the magnitude is, the developed model is equally applicable to any change in temperature. Title: Power core (PC) Embedding a Plurality of IC Devices and Sandwiched Between Two Dissimilar Insulated Metal Substrates (IMS’): Predicted Thermal Stresses Author: Suhir, Ephraim, Nicolics, Johann Year: 2016 Power core (PC) sandwiched between two insulated metal substrates (IMS) and embedding active and passive integrated circuit (IC) devices is currently viewed as an attractive advanced packaging option having a strong potential in the automotive industry and beyond. A natural reliability concern, however, is the level of the thermally induced stresses in a tri-material assembly of the type in question. Accordingly, an analytical (mathematical) stress model is developed for the evaluation of these stresses. The stresses include normal stresses acting in the cross-sections of the assembly components, and the interfacial shearing and peeling stresses acting at the interfaces of these components and at the interfaces of the embedded IC devices. The model can be helpful in the stress-analysis and physical design of the assemblies, in which the PC is sandwiched between two IMS’. It can be used also in other areas of engineering, where tri-material assemblies comprised of dissimilar materials and subjected to the change in temperature are employed. The general concepts are illustrated by a detailed numerical example. The analysis is an extension of the study carried out earlier for a bow-free assembly. It is noteworthy that although the calculations are carried out for the case when the assembly is cooled down from an elevated temperature to a low temperature, since a linear approach is used and the stresses are proportional to the change in temperature, whatever its sign or the magnitude is, the developed model is equally applicable to any change in temperature. Close