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• 11. [Article] Determining Initial Firing Temperatures of Thule Era (1000-250 ya) Pottery from Two Northwest Alaskan Archaeological Sites

  This research was conducted to investigate the initial firing temperatures (IFT) of pottery from two archaeological sites in Northwest Alaska. Arctic ceramics are consistently described as low-fired technology ...

  Citation × Citation Citation Abstract Copy Title: Determining Initial Firing Temperatures of Thule Era (1000-250 ya) Pottery from Two Northwest Alaskan Archaeological Sites Author: Duelks, Jonathan Year: 2015 This research was conducted to investigate the initial firing temperatures (IFT) of pottery from two archaeological sites in Northwest Alaska. Arctic ceramics are consistently described as low-fired technology in archaeological and ethnographic literature. However, regional and temporal variation in the quality and hardness of arctic ceramics suggests variation in firing temperatures. To describe all Arctic pottery as low-fired ignores variation in firing temperatures and ultimately in the production process. Sherds from two archaeological locales, the Cape Krusenstern site complex and the Ahteut village site, were selected to represent sites with differential access to fuel resources. IFT’s were estimated by measuring color change in a stepwise refiring experiment. Preliminary results indicate that a majority of sherds from Cape Krusenstern had lower initial firing temperatures than did sherds from Ahteut. Additionally, this experiment indicates that (1) a majority of the sherds contained residual organic content, (2) shows the effects of the presence of organic content on a refiring experiment, and (3) confirms that vessels from these two sites were originally fired under reducing atmospheres. These results do provide a better understanding of the production process of arctic ceramics. The difference between the initial firing atmosphere and the refiring atmosphere, as well as the presence of organic content, may be masking the true indications of initial firing temperatures. Because of these confounding factors additional research, including alternative methods of estimating initial firing temperatures, are necessary. Beyond reconstructing the production process of Northwest Alaskan ceramics, understanding initial firing temperatures provides important information regarding environmental constraints on the ceramic production process and the methods precontact potters used to overcome them. This work also adds to our understanding of fuel use and management. Title: Determining Initial Firing Temperatures of Thule Era (1000-250 ya) Pottery from Two Northwest Alaskan Archaeological Sites Author: Duelks, Jonathan Year: 2015 This research was conducted to investigate the initial firing temperatures (IFT) of pottery from two archaeological sites in Northwest Alaska. Arctic ceramics are consistently described as low-fired technology in archaeological and ethnographic literature. However, regional and temporal variation in the quality and hardness of arctic ceramics suggests variation in firing temperatures. To describe all Arctic pottery as low-fired ignores variation in firing temperatures and ultimately in the production process. Sherds from two archaeological locales, the Cape Krusenstern site complex and the Ahteut village site, were selected to represent sites with differential access to fuel resources. IFT’s were estimated by measuring color change in a stepwise refiring experiment. Preliminary results indicate that a majority of sherds from Cape Krusenstern had lower initial firing temperatures than did sherds from Ahteut. Additionally, this experiment indicates that (1) a majority of the sherds contained residual organic content, (2) shows the effects of the presence of organic content on a refiring experiment, and (3) confirms that vessels from these two sites were originally fired under reducing atmospheres. These results do provide a better understanding of the production process of arctic ceramics. The difference between the initial firing atmosphere and the refiring atmosphere, as well as the presence of organic content, may be masking the true indications of initial firing temperatures. Because of these confounding factors additional research, including alternative methods of estimating initial firing temperatures, are necessary. Beyond reconstructing the production process of Northwest Alaskan ceramics, understanding initial firing temperatures provides important information regarding environmental constraints on the ceramic production process and the methods precontact potters used to overcome them. This work also adds to our understanding of fuel use and management. Close

• 12. [Article] Hydrodynamic and Water Quality Modeling of the Chehalis River Using CE-QUAL-W2

  The Chehalis River Basin is located in the southwest region of Washington State, originating in the Olympic Mountains and flowing to Grays Harbor and the Pacific Ocean. The Chehalis River is over 125 miles, ...

  Citation × Citation Citation Abstract Copy Title: Hydrodynamic and Water Quality Modeling of the Chehalis River Using CE-QUAL-W2 Author: Van Glubt, Sarah Year: 2017 The Chehalis River Basin is located in the southwest region of Washington State, originating in the Olympic Mountains and flowing to Grays Harbor and the Pacific Ocean. The Chehalis River is over 125 miles, exists within five counties, and flows through agricultural, residential, industrial, and forest land areas. Four major rivers discharge to the Chehalis River, as well as many smaller creeks, five wastewater treatment plants, and groundwater flows. Flooding is a major problem in the relatively flat areas surrounding the cities of Chehalis and Centralia, with severe consequences for property, safety and transportation. 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, and has had multiple water quality and Total Maximum Daily Load studies beginning in 1990. 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. This involved developing meteorological data, riparian shading data, and flow, temperature, water quality records for all tributaries during the calibration period of January 1, 2013 to December 31, 2014. System cross-sectional geometry data were also required for the model grid. Because of the short travel time in the river, the model was sensitive to boundary condition data, wind speed, bathymetry, nutrient kinetics, and algae, epiphyton, and zooplankton kinetics. 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 also showed impacts to river temperature and water quality. 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. As this research continues improvements will be made, particularly to temperature and water quality constituents. Additional data for the system would be beneficial to this process. Model predictions of temperature were sensitive to meteorological data, including cloud cover, which were largely estimated based on solar radiation. Additional meteorological data throughout the basin would be useful to temperature results. Temperature results were also sensitive to the model bathymetry, and additional investigations into segments widths and water depths may improve temperature predictions. Water quality constituent data were largely lacking for the system. Many estimation techniques and approximations were used for input water quality constituents for the model upstream boundary and tributaries when little or no data were available, introducing uncertainty to the model. It was not possible to calibrate pH to field data because alkalinity data were essentially unavailable. However, other constituents had good agreement between model predictions and field data, including dissolved oxygen, nitrates, total phosphorus, and total suspended solids. Title: Hydrodynamic and Water Quality Modeling of the Chehalis River Using CE-QUAL-W2 Author: Van Glubt, Sarah Year: 2017 The Chehalis River Basin is located in the southwest region of Washington State, originating in the Olympic Mountains and flowing to Grays Harbor and the Pacific Ocean. The Chehalis River is over 125 miles, exists within five counties, and flows through agricultural, residential, industrial, and forest land areas. Four major rivers discharge to the Chehalis River, as well as many smaller creeks, five wastewater treatment plants, and groundwater flows. Flooding is a major problem in the relatively flat areas surrounding the cities of Chehalis and Centralia, with severe consequences for property, safety and transportation. 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, and has had multiple water quality and Total Maximum Daily Load studies beginning in 1990. 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. This involved developing meteorological data, riparian shading data, and flow, temperature, water quality records for all tributaries during the calibration period of January 1, 2013 to December 31, 2014. System cross-sectional geometry data were also required for the model grid. Because of the short travel time in the river, the model was sensitive to boundary condition data, wind speed, bathymetry, nutrient kinetics, and algae, epiphyton, and zooplankton kinetics. 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 also showed impacts to river temperature and water quality. 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. As this research continues improvements will be made, particularly to temperature and water quality constituents. Additional data for the system would be beneficial to this process. Model predictions of temperature were sensitive to meteorological data, including cloud cover, which were largely estimated based on solar radiation. Additional meteorological data throughout the basin would be useful to temperature results. Temperature results were also sensitive to the model bathymetry, and additional investigations into segments widths and water depths may improve temperature predictions. Water quality constituent data were largely lacking for the system. Many estimation techniques and approximations were used for input water quality constituents for the model upstream boundary and tributaries when little or no data were available, introducing uncertainty to the model. It was not possible to calibrate pH to field data because alkalinity data were essentially unavailable. However, other constituents had good agreement between model predictions and field data, including dissolved oxygen, nitrates, total phosphorus, and total suspended solids. Close

• 13. [Article] Approximate Equations of State in Two-Temperature Plasma Mixtures

  Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring ...

  Citation × Citation Citation Abstract Copy Title: Approximate Equations of State in Two-Temperature Plasma Mixtures Author: Ramshaw, John D., Cook, Andrew W. Year: 2014 Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring the separated materials to be in temperature and pressure equilibrium. Iterative numerical algorithms have been employed to enforce this equilibration and compute the resulting approximate state relations in single-temperature mixtures. In partially ionized gas mixtures, there is both theoretical and empirical evidence that equilibrating the chemical potentials, number densities, or partial pressures of the free electrons is likely to produce more accurate results than equilibrating the total pressures. Moreover, in many situations of practical interest the free electrons and heavy particles have different temperatures. In this paper, we present a generalized algorithm for equilibrating the heavy-particle and electron temperaturesand a third user-specified independent thermodynamic variable in a two-temperature plasmamixture. Test calculations based on the equilibration of total pressure vs. electron pressure are presented for three different mixtures. Title: Approximate Equations of State in Two-Temperature Plasma Mixtures Author: Ramshaw, John D., Cook, Andrew W. Year: 2014 Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring the separated materials to be in temperature and pressure equilibrium. Iterative numerical algorithms have been employed to enforce this equilibration and compute the resulting approximate state relations in single-temperature mixtures. In partially ionized gas mixtures, there is both theoretical and empirical evidence that equilibrating the chemical potentials, number densities, or partial pressures of the free electrons is likely to produce more accurate results than equilibrating the total pressures. Moreover, in many situations of practical interest the free electrons and heavy particles have different temperatures. In this paper, we present a generalized algorithm for equilibrating the heavy-particle and electron temperaturesand a third user-specified independent thermodynamic variable in a two-temperature plasmamixture. Test calculations based on the equilibration of total pressure vs. electron pressure are presented for three different mixtures. Close

• 14. [Article] TEMPERATURE CHANGES IN HUMAN SKELETAL MUSCLE DURING SINGLE LEG DYNAMIC KNEE EXTENSION EXERCISE

  49 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Arts, Summer ...

  Citation × Citation Citation Abstract Copy Title: TEMPERATURE CHANGES IN HUMAN SKELETAL MUSCLE DURING SINGLE LEG DYNAMIC KNEE EXTENSION EXERCISE Author: Peck, Mairin Year: 2016, 2015 49 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Arts, Summer 2015. Title: TEMPERATURE CHANGES IN HUMAN SKELETAL MUSCLE DURING SINGLE LEG DYNAMIC KNEE EXTENSION EXERCISE Author: Peck, Mairin Year: 2016, 2015 49 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Arts, Summer 2015. Close

• 15. [Article] Towards p-Type Conductivity in SnO2Nanocrystals through Li Doping and Its Applications in Porous Diodes for Room Temperature Chlorine Gas Detection

  This work examined electrical transport properties and Li doping in SnO2synthesized by the sol–gel method. Solid-state 7Li-NMR line shapes revealed that Li ions occupy two distinct sites with differing ...

  Citation × Citation Citation Abstract Copy Title: Towards p-Type Conductivity in SnO2Nanocrystals through Li Doping and Its Applications in Porous Diodes for Room Temperature Chlorine Gas Detection Author: Chaparadza, Allen, Rananavare, Shankar Year: 2016 This work examined electrical transport properties and Li doping in SnO2synthesized by the sol–gel method. Solid-state 7Li-NMR line shapes revealed that Li ions occupy two distinct sites with differing dynamic mobilities. The chemical exchange rate between the two sites is, however, too slow for detection on the NMR timescale. Compressed nanoparticulate films of this doped semiconductor exhibited a positive Seebeck coefficient implying a p-type conductivity. A variable-temperature direct current conductivity, over a 25–350 °C temperature range, followed an Efros–Shklovskii variable range hopping (ES-VRH) conduction mechanism (ln(ρ) versus T−1/2) at temperatures below 100 °C with a crossover to 2D Mott variable range hopping (M-VRH) (ln(ρ) versus T−1/3) conduction at temperatures above 250 °C. In a transition region between these two limiting behaviors, direct current resistivity exhibited an anomalous temperature-independent plateau. We suggest that its origin may lie in a carrier inversion phenomenon wherein the majority carriers switch from holes to electrons due to Li ion expulsion from the crystalline core and creation of oxygen vacancies generated by loss of oxygen at elevated temperatures. Using a compression technique, porous diodes consisting of n-type (antimony doped SnO2) and the p-type (lithium-doped) nano-particulate films were prepared. Typical current-voltage curves of such devices resembled the behavior of a typical diode but for one key difference; owing to the porosity of the film, areas near the p-n interface and the p- and n-regions are accessible to gaseous analytes. This access is not possible in conventional diodes fabricated through contemporary planar technology. The gas sensing properties of the diodes were investigated by using Cl2, Br2, HCl, NO, NO2, CHCl3, NH3 and H2. Of all the gases tested, the sensor had very good sensitivity to Cl2 and had a response of 80 at 400 ppb of Cl2. The response time of the sensor was ~30 s at room temperature but the recovery time was temperature dependent. At room temperature the recovery time was 80s after 400 ppb chlorine exposure. The sensors were also found to recover quickly (~ 30 s) when the junctions were biased. Reverse biasing the diode provides a controllable band-bending at a p-n junction that could influence the electron-transfer rates from the adsorbates which create intra-band localized states. As a result reverse biasing can provide a means of desorbing the analyzed species. This approach eliminates the requirement to remove adsorbates by elevating the sensor temperature and hence improves on the energy efficiency of these types of sensors. Title: Towards p-Type Conductivity in SnO2Nanocrystals through Li Doping and Its Applications in Porous Diodes for Room Temperature Chlorine Gas Detection Author: Chaparadza, Allen, Rananavare, Shankar Year: 2016 This work examined electrical transport properties and Li doping in SnO2synthesized by the sol–gel method. Solid-state 7Li-NMR line shapes revealed that Li ions occupy two distinct sites with differing dynamic mobilities. The chemical exchange rate between the two sites is, however, too slow for detection on the NMR timescale. Compressed nanoparticulate films of this doped semiconductor exhibited a positive Seebeck coefficient implying a p-type conductivity. A variable-temperature direct current conductivity, over a 25–350 °C temperature range, followed an Efros–Shklovskii variable range hopping (ES-VRH) conduction mechanism (ln(ρ) versus T−1/2) at temperatures below 100 °C with a crossover to 2D Mott variable range hopping (M-VRH) (ln(ρ) versus T−1/3) conduction at temperatures above 250 °C. In a transition region between these two limiting behaviors, direct current resistivity exhibited an anomalous temperature-independent plateau. We suggest that its origin may lie in a carrier inversion phenomenon wherein the majority carriers switch from holes to electrons due to Li ion expulsion from the crystalline core and creation of oxygen vacancies generated by loss of oxygen at elevated temperatures. Using a compression technique, porous diodes consisting of n-type (antimony doped SnO2) and the p-type (lithium-doped) nano-particulate films were prepared. Typical current-voltage curves of such devices resembled the behavior of a typical diode but for one key difference; owing to the porosity of the film, areas near the p-n interface and the p- and n-regions are accessible to gaseous analytes. This access is not possible in conventional diodes fabricated through contemporary planar technology. The gas sensing properties of the diodes were investigated by using Cl2, Br2, HCl, NO, NO2, CHCl3, NH3 and H2. Of all the gases tested, the sensor had very good sensitivity to Cl2 and had a response of 80 at 400 ppb of Cl2. The response time of the sensor was ~30 s at room temperature but the recovery time was temperature dependent. At room temperature the recovery time was 80s after 400 ppb chlorine exposure. The sensors were also found to recover quickly (~ 30 s) when the junctions were biased. Reverse biasing the diode provides a controllable band-bending at a p-n junction that could influence the electron-transfer rates from the adsorbates which create intra-band localized states. As a result reverse biasing can provide a means of desorbing the analyzed species. This approach eliminates the requirement to remove adsorbates by elevating the sensor temperature and hence improves on the energy efficiency of these types of sensors. Close

• 16. [Article] Daytime Variation of Urban Heat Islands: The Case Study of Doha, Qatar

  Recent evidence suggests that urban forms and materials can help to mediate temporal variation of microclimates and that landscape modifications can potentially reduce temperatures and increase accessibility ...

  Citation × Citation Citation Abstract Copy Title: Daytime Variation of Urban Heat Islands: The Case Study of Doha, Qatar Author: Makido, Yasuyo, Shandas, Vivek, Ferwati, Salim, Sailor, David J. Year: 2016 Recent evidence suggests that urban forms and materials can help to mediate temporal variation of microclimates and that landscape modifications can potentially reduce temperatures and increase accessibility to outdoor environments. To understand the relationship between urban form and temperature moderation, we examined the spatial and temporal variation of air temperature throughout one desert city—Doha, Qatar—by conducting vehicle traverses using highly resolved temperature and GPS data logs to determine spatial differences in summertime air temperatures. To help explain near-surface air temperatures using land cover variables, we employed three statistical approaches: Ordinary Least Squares (OLS), Regression Tree Analysis (RTA), and Random Forest (RF). We validated the predictions of the statistical models by computing the Root Mean Square Error (RMSE) and discovered that temporal variations in urban heat are mediated by different factors throughout the day. The average RMSE for OLS, RTA and RF is 1.25, 0.96, and 0.65 (in Celsius), respectively, suggesting that the RF is the best model for predicting near-surface air temperatures at this study site. We conclude by recommending the features of the landscape that have the greatest potential for reducing extreme heat in arid climates. Title: Daytime Variation of Urban Heat Islands: The Case Study of Doha, Qatar Author: Makido, Yasuyo, Shandas, Vivek, Ferwati, Salim, Sailor, David J. Year: 2016 Recent evidence suggests that urban forms and materials can help to mediate temporal variation of microclimates and that landscape modifications can potentially reduce temperatures and increase accessibility to outdoor environments. To understand the relationship between urban form and temperature moderation, we examined the spatial and temporal variation of air temperature throughout one desert city—Doha, Qatar—by conducting vehicle traverses using highly resolved temperature and GPS data logs to determine spatial differences in summertime air temperatures. To help explain near-surface air temperatures using land cover variables, we employed three statistical approaches: Ordinary Least Squares (OLS), Regression Tree Analysis (RTA), and Random Forest (RF). We validated the predictions of the statistical models by computing the Root Mean Square Error (RMSE) and discovered that temporal variations in urban heat are mediated by different factors throughout the day. The average RMSE for OLS, RTA and RF is 1.25, 0.96, and 0.65 (in Celsius), respectively, suggesting that the RF is the best model for predicting near-surface air temperatures at this study site. We conclude by recommending the features of the landscape that have the greatest potential for reducing extreme heat in arid climates. Close

• 17. [Article] Estimation of Transient Temperature Distribution during Quenching, via a Parabolic Model

  A material-independent model to estimate the transient temperature distribution in a test probe quenched by immersion is presented in this study. This model is based on the assumption that, under one-dimensional ...

  Citation × Citation Citation Abstract Copy Title: Estimation of Transient Temperature Distribution during Quenching, via a Parabolic Model Author: Lozano, Diego E., Martinez-Solis, Gabriela, Mercado-Solis, Rafael David, Colás, Rafael, Totten, George E. Year: 2015 A material-independent model to estimate the transient temperature distribution in a test probe quenched by immersion is presented in this study. This model is based on the assumption that, under one-dimensional unsteady heat conduction, the radial temperature distribution at the end of an interval belongs to the equation of a parabola. The model was validated using AISI 304 stainless steel test probes (Φ8×40 mm and Φ12×60 mm) quenched from 850 to 900 °C in water and in water-based NaNO2 solutions at 25 °C and in canola oil at 50 °C. Additionally, square test probes (20×20×100 mm) were quenched from 550 °C in water. The test probes were equipped with embedded thermocouples for temperature-versus-time data logging at the core, one-quarter thickness and 1 mm below the surface. In each experiment, the data recordings from the core and near-surface thermocouples were employed for the temperature calculations while the data from the one-quarter thickness thermocouple were employed for model validity verifications. In all cases, the calculated temperature distributions showed good correlations with the experimentally obtained values. Based on the results of this work, it is concluded that this approach constitutes a simple, quick and efficient tool for estimating transient surface and radial temperature distributions and represents a useful resource for quenchant cooling rate calculations and heat transfer characterizations. Title: Estimation of Transient Temperature Distribution during Quenching, via a Parabolic Model Author: Lozano, Diego E., Martinez-Solis, Gabriela, Mercado-Solis, Rafael David, Colás, Rafael, Totten, George E. Year: 2015 A material-independent model to estimate the transient temperature distribution in a test probe quenched by immersion is presented in this study. This model is based on the assumption that, under one-dimensional unsteady heat conduction, the radial temperature distribution at the end of an interval belongs to the equation of a parabola. The model was validated using AISI 304 stainless steel test probes (Φ8×40 mm and Φ12×60 mm) quenched from 850 to 900 °C in water and in water-based NaNO2 solutions at 25 °C and in canola oil at 50 °C. Additionally, square test probes (20×20×100 mm) were quenched from 550 °C in water. The test probes were equipped with embedded thermocouples for temperature-versus-time data logging at the core, one-quarter thickness and 1 mm below the surface. In each experiment, the data recordings from the core and near-surface thermocouples were employed for the temperature calculations while the data from the one-quarter thickness thermocouple were employed for model validity verifications. In all cases, the calculated temperature distributions showed good correlations with the experimentally obtained values. Based on the results of this work, it is concluded that this approach constitutes a simple, quick and efficient tool for estimating transient surface and radial temperature distributions and represents a useful resource for quenchant cooling rate calculations and heat transfer characterizations. Close

• 18. [Article] Solder Material Experiencing Low Temperature Inelastic Stress and Random Vibration Loading: Predicted Remaining Useful Lifetime

  Although there exist promising ways to avoid inelastic strains in solder joints of the second level interconnections in IC package designs, it still appears more typical than not that the peripheral joints ...

  Citation × Citation Citation Abstract Copy Title: Solder Material Experiencing Low Temperature Inelastic Stress and Random Vibration Loading: Predicted Remaining Useful Lifetime Author: Suhir, Ephraim, Ghaffarian, Reza, Yi, Sung Year: 2017 Although there exist promising ways to avoid inelastic strains in solder joints of the second level interconnections in IC package designs, it still appears more typical than not that the peripheral joints of a package/PCB assembly experience inelastic strains. This takes place at low temperature conditions, when the deviation from the high fabrication temperature is the largest and the induced thermal stresses are the highest. On the other hand, it is well known that it is the combination of low temperatures and repetitive dynamic loading that accelerate dramatically the propagation of fatigue cracks, whether elastic or inelastic. Accordingly, a modification of the recently suggested Boltzmann–Arrhenius–Zhurkov model is developed for the evaluation of the remaining useful lifetime of the second level solder joint interconnection whose peripheral joints experience inelastic strains. The experimental basis of the approach is the highly focused and highly cost-effective failure-oriented-accelerated-testing (FOAT). The FOAT specimens are subjected in our methodology to the combined action of low temperatures (not to elevated temperatures, as in the classical Arrhenius model) and random vibrations with the given input energy spectrum. The suggested methodology is viewed as a possible, effective and attractive alternative to temperature cycling. As long as inelastic deformations take place, it is assumed that it is these deformations that determine the fatigue lifetime of the solder material, and the state of stress in the elastic mid-portion of the assembly does not have to be accounted for. The roles of the size and stiffness of this mid-portion have to be considered, however, when determining the very existence and establishing the size of the inelastic zones at the peripheral portions of the designs. The general concept is illustrated by a numerical example. Although this example is carried out for a ball-grid-array design, it is applicable to highly popular column-grid-array (CGA) and quad-flat-no-lead (QFN) designs as well. It is noteworthy that it is much easier to avoid inelastic strains in CGA and QFN structures than in the addressed BGA design. The random vibrations are considered in the developed methodology as a white noise of the given (m/s2)2/Hz—the ratio of the acceleration amplitudes squared to the vibration frequency. © 2016, Springer Science+Business Media New York. Title: Solder Material Experiencing Low Temperature Inelastic Stress and Random Vibration Loading: Predicted Remaining Useful Lifetime Author: Suhir, Ephraim, Ghaffarian, Reza, Yi, Sung Year: 2017 Although there exist promising ways to avoid inelastic strains in solder joints of the second level interconnections in IC package designs, it still appears more typical than not that the peripheral joints of a package/PCB assembly experience inelastic strains. This takes place at low temperature conditions, when the deviation from the high fabrication temperature is the largest and the induced thermal stresses are the highest. On the other hand, it is well known that it is the combination of low temperatures and repetitive dynamic loading that accelerate dramatically the propagation of fatigue cracks, whether elastic or inelastic. Accordingly, a modification of the recently suggested Boltzmann–Arrhenius–Zhurkov model is developed for the evaluation of the remaining useful lifetime of the second level solder joint interconnection whose peripheral joints experience inelastic strains. The experimental basis of the approach is the highly focused and highly cost-effective failure-oriented-accelerated-testing (FOAT). The FOAT specimens are subjected in our methodology to the combined action of low temperatures (not to elevated temperatures, as in the classical Arrhenius model) and random vibrations with the given input energy spectrum. The suggested methodology is viewed as a possible, effective and attractive alternative to temperature cycling. As long as inelastic deformations take place, it is assumed that it is these deformations that determine the fatigue lifetime of the solder material, and the state of stress in the elastic mid-portion of the assembly does not have to be accounted for. The roles of the size and stiffness of this mid-portion have to be considered, however, when determining the very existence and establishing the size of the inelastic zones at the peripheral portions of the designs. The general concept is illustrated by a numerical example. Although this example is carried out for a ball-grid-array design, it is applicable to highly popular column-grid-array (CGA) and quad-flat-no-lead (QFN) designs as well. It is noteworthy that it is much easier to avoid inelastic strains in CGA and QFN structures than in the addressed BGA design. The random vibrations are considered in the developed methodology as a white noise of the given (m/s2)2/Hz—the ratio of the acceleration amplitudes squared to the vibration frequency. © 2016, Springer Science+Business Media New York. Close

• 19. [Article] Evaluation of Large‑Scale Meteorological Patterns Associated with Temperature Extremes in the NARCCAP Regional Climate Model Simulations

  Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate ...

  Citation × Citation Citation Abstract Copy Title: Evaluation of Large‑Scale Meteorological Patterns Associated with Temperature Extremes in the NARCCAP Regional Climate Model Simulations Author: Loikith, Paul C., Waliser, Duane E., Lee, Huikyo, Neelin, J. David, Lintner, Benjamin, McGinnis, Seth, Mears, Linda, Kim, Jinwon Year: 2015 Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate Change Assessment Program. LSMPs are characterized through composites of surface air temperature, sea level pressure, and 500 hPa geopotential height anomalies concurrent with extreme temperature days. Six of the seventeen RCM simulations are driven by boundary conditions from reanalysis while the other eleven are driven by one of four global climate models (GCMs). Four illustrative case studies are analyzed in detail. Model fidelity in LSMP spatial representation is high for cold winter extremes near Chicago. Winter warm extremes are captured by most RCMs in northern California, with some notable exceptions. Model fidelity is lower for cool summer days near Houston and extreme summer heat events in the Ohio Valley. Physical interpretation of these patterns and identification of wellsimulated cases, such as for Chicago, boosts confidence in the ability of these models to simulate days in the tails of the temperature distribution. Results appear consistent with the expectation that the ability of an RCM to reproduce a realistically shaped frequency distribution for temperature, especially at the tails, is related to its fidelity in simulating LMSPs. Each ensemble member is ranked for its ability to reproduce LSMPs associated with observed warm and cold extremes, identifying systematically high performing RCMs and the GCMs that provide superior boundary forcing. The methodology developed here provides a framework for identifying regions where further process-based evaluation would improve the understanding of simulation error and help guide future model improvement and downscaling efforts. Title: Evaluation of Large‑Scale Meteorological Patterns Associated with Temperature Extremes in the NARCCAP Regional Climate Model Simulations Author: Loikith, Paul C., Waliser, Duane E., Lee, Huikyo, Neelin, J. David, Lintner, Benjamin, McGinnis, Seth, Mears, Linda, Kim, Jinwon Year: 2015 Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate Change Assessment Program. LSMPs are characterized through composites of surface air temperature, sea level pressure, and 500 hPa geopotential height anomalies concurrent with extreme temperature days. Six of the seventeen RCM simulations are driven by boundary conditions from reanalysis while the other eleven are driven by one of four global climate models (GCMs). Four illustrative case studies are analyzed in detail. Model fidelity in LSMP spatial representation is high for cold winter extremes near Chicago. Winter warm extremes are captured by most RCMs in northern California, with some notable exceptions. Model fidelity is lower for cool summer days near Houston and extreme summer heat events in the Ohio Valley. Physical interpretation of these patterns and identification of wellsimulated cases, such as for Chicago, boosts confidence in the ability of these models to simulate days in the tails of the temperature distribution. Results appear consistent with the expectation that the ability of an RCM to reproduce a realistically shaped frequency distribution for temperature, especially at the tails, is related to its fidelity in simulating LMSPs. Each ensemble member is ranked for its ability to reproduce LSMPs associated with observed warm and cold extremes, identifying systematically high performing RCMs and the GCMs that provide superior boundary forcing. The methodology developed here provides a framework for identifying regions where further process-based evaluation would improve the understanding of simulation error and help guide future model improvement and downscaling efforts. Close

• 20. [Article] A Metabolic Hypothesis for the Evolution of Temperature Effects on the Arterial PCO2 and pH of Vertebrate Ectotherms

  Body temperature increases in ectothermic vertebrates characteristically lead to both increases in arterial PCO2 (PaCO2) and declines in resting arterial pH (pHa) of about 0.017 pH units/°C increase in ...

  Citation × Citation Citation Abstract Copy Title: A Metabolic Hypothesis for the Evolution of Temperature Effects on the Arterial PCO2 and pH of Vertebrate Ectotherms Author: Hillman, Stanley S., Hedrick, Michael Scott Year: 2017 Body temperature increases in ectothermic vertebrates characteristically lead to both increases in arterial PCO2 (PaCO2) and declines in resting arterial pH (pHa) of about 0.017 pH units/°C increase in temperature. This ‘alphastat’ pH pattern has previously been interpreted as being evolutionarily-driven by the maintenance of a constant protonation state on the imidazole moiety of histidine protein residues, hence stabilizing protein structure-function. Analysis of the existing data for interclass responses of ectothermic vertebrates show different degrees of PaCO2 increases and pH declines with temperature between the classes with reptiles>amphibians>fish. The PaCO2 at the temperature where maximal aerobic metabolism (VO2max) is achieved is significantly and positively correlated with temperature for all vertebrate classes. For ectotherms, the PaCO2 where VO2max is greatest is also correlated with VO2max indicating there is an increased driving force for CO2 efflux that is lowest in fish, intermediate in amphibians and highest in reptiles. The pattern of increased PaCO2 and the resultant reduction of pHa to increased body temperature would serve to increase CO2 efflux, O2 delivery, blood buffering capacity and maintain ventilatory scope. This represents a new hypothesis for the selective advantage of arterial pH regulation from a systems physiology perspective in addition to the advantages of maintenance of protein structure-function. Title: A Metabolic Hypothesis for the Evolution of Temperature Effects on the Arterial PCO2 and pH of Vertebrate Ectotherms Author: Hillman, Stanley S., Hedrick, Michael Scott Year: 2017 Body temperature increases in ectothermic vertebrates characteristically lead to both increases in arterial PCO2 (PaCO2) and declines in resting arterial pH (pHa) of about 0.017 pH units/°C increase in temperature. This ‘alphastat’ pH pattern has previously been interpreted as being evolutionarily-driven by the maintenance of a constant protonation state on the imidazole moiety of histidine protein residues, hence stabilizing protein structure-function. Analysis of the existing data for interclass responses of ectothermic vertebrates show different degrees of PaCO2 increases and pH declines with temperature between the classes with reptiles>amphibians>fish. The PaCO2 at the temperature where maximal aerobic metabolism (VO2max) is achieved is significantly and positively correlated with temperature for all vertebrate classes. For ectotherms, the PaCO2 where VO2max is greatest is also correlated with VO2max indicating there is an increased driving force for CO2 efflux that is lowest in fish, intermediate in amphibians and highest in reptiles. The pattern of increased PaCO2 and the resultant reduction of pHa to increased body temperature would serve to increase CO2 efflux, O2 delivery, blood buffering capacity and maintain ventilatory scope. This represents a new hypothesis for the selective advantage of arterial pH regulation from a systems physiology perspective in addition to the advantages of maintenance of protein structure-function. Close