Search

Search Results

• 1. [Article] Numerical Modeling and Analyses of Steel Bridge Gusset Plate Connections

  Gusset plate connections are commonly used in steel truss bridges to connect individual members together at a node. Many of these bridges are classified as non-load-path-redundant bridges, meaning a failure ...

  Citation × Citation Citation Abstract Copy Title: Numerical Modeling and Analyses of Steel Bridge Gusset Plate Connections Author: Kay, Thomas Sidney Year: 2011 Gusset plate connections are commonly used in steel truss bridges to connect individual members together at a node. Many of these bridges are classified as non-load-path-redundant bridges, meaning a failure of a single truss member or connection could lead to collapse. Current gusset plated design philosophy is based upon experimental work from simplified, small-scale connections which are seldom representative of bridge connections. This makes development of a refined methodology for conducting high-fidelity strength capacity evaluations for existing bridge connections a highly desirable goal. The primary goal of this research effort is to develop an analytical model capable of evaluating gusset plate stresses and ultimate strength limit states. A connection-level gusset connection model was developed in parallel with an experimental testing program at Oregon State University. Data was collected on elastic stress distributions and ultimate buckling capacity. The analytical model compared different bolt modeling techniques on their effectiveness in predicting buckling loads and stress distributions. Analytical tensile capacity was compared to the current bridge gusset plate design equations for block shear. Results from the elastic stress analysis showed no significant differences between the bolt modeling techniques examined, and moderate correlation between analytical and experimental values. Results from the analytical model predicted experimental buckling capacity within 10% for most of the bolt modeling techniques examined. Tensile capacity was within 7% of the calculated tensile nominal capacity for all bolt modeling techniques examined. A preliminary parametric study was conducted to investigate the effects of member flexural stiffness and length on gusset plate buckling capacity, and showed an increase in member length or decrease in member flexural stiffness resulted in diminished gusset plate buckling capacity. Title: Numerical Modeling and Analyses of Steel Bridge Gusset Plate Connections Author: Kay, Thomas Sidney Year: 2011 Gusset plate connections are commonly used in steel truss bridges to connect individual members together at a node. Many of these bridges are classified as non-load-path-redundant bridges, meaning a failure of a single truss member or connection could lead to collapse. Current gusset plated design philosophy is based upon experimental work from simplified, small-scale connections which are seldom representative of bridge connections. This makes development of a refined methodology for conducting high-fidelity strength capacity evaluations for existing bridge connections a highly desirable goal. The primary goal of this research effort is to develop an analytical model capable of evaluating gusset plate stresses and ultimate strength limit states. A connection-level gusset connection model was developed in parallel with an experimental testing program at Oregon State University. Data was collected on elastic stress distributions and ultimate buckling capacity. The analytical model compared different bolt modeling techniques on their effectiveness in predicting buckling loads and stress distributions. Analytical tensile capacity was compared to the current bridge gusset plate design equations for block shear. Results from the elastic stress analysis showed no significant differences between the bolt modeling techniques examined, and moderate correlation between analytical and experimental values. Results from the analytical model predicted experimental buckling capacity within 10% for most of the bolt modeling techniques examined. Tensile capacity was within 7% of the calculated tensile nominal capacity for all bolt modeling techniques examined. A preliminary parametric study was conducted to investigate the effects of member flexural stiffness and length on gusset plate buckling capacity, and showed an increase in member length or decrease in member flexural stiffness resulted in diminished gusset plate buckling capacity. Close

• 2. [Article] Analysis of Induced Travel in the 1995 NPTS

  In this paper we estimate the relationship between road capacity and vehicle miles of travel (VMT) from a sample of 12,000 respondents from 48 urban areas in the 1995 Nationwide Personal Transportation ...

  Citation × Citation Citation Abstract Copy Title: Analysis of Induced Travel in the 1995 NPTS Author: Strathman, James G., Dueker, Kenneth, Sanchez, Thomas W., Zhang, Jihong, Riis, Ann-Elizabeth Year: 2000 In this paper we estimate the relationship between road capacity and vehicle miles of travel (VMT) from a sample of 12,000 respondents from 48 urban areas in the 1995 Nationwide Personal Transportation Survey (NPTS). Our approach seeks to account for the effects of residential location, employment location, and commute mode choice in estimating the effect of capacity on VMT. VMT is found to be directly related to road capacity, as well as indirectly related through the influence of road capacity on residential and work place densities. Title: Analysis of Induced Travel in the 1995 NPTS Author: Strathman, James G., Dueker, Kenneth, Sanchez, Thomas W., Zhang, Jihong, Riis, Ann-Elizabeth Year: 2000 In this paper we estimate the relationship between road capacity and vehicle miles of travel (VMT) from a sample of 12,000 respondents from 48 urban areas in the 1995 Nationwide Personal Transportation Survey (NPTS). Our approach seeks to account for the effects of residential location, employment location, and commute mode choice in estimating the effect of capacity on VMT. VMT is found to be directly related to road capacity, as well as indirectly related through the influence of road capacity on residential and work place densities. Close

• 3. [Article] New Lathe Decision

  Consolidated Metco produces cast aluminum truck parts for class 8 trucks. The company has two plant locations and intends to expand in capacity to meet the increasing demand. The plant manager wants to ...

  Citation × Citation Citation Abstract Copy Title: New Lathe Decision Author: Smith, Don Year: 1993 Consolidated Metco produces cast aluminum truck parts for class 8 trucks. The company has two plant locations and intends to expand in capacity to meet the increasing demand. The plant manager wants to purchase a new lathe or lathes to provide adequate capacity. The author assesses the capacity requirements and evaluates the candidate machines. He compares the technical and financial options. He conducts an economic analysis to reach the final decision. Title: New Lathe Decision Author: Smith, Don Year: 1993 Consolidated Metco produces cast aluminum truck parts for class 8 trucks. The company has two plant locations and intends to expand in capacity to meet the increasing demand. The plant manager wants to purchase a new lathe or lathes to provide adequate capacity. The author assesses the capacity requirements and evaluates the candidate machines. He compares the technical and financial options. He conducts an economic analysis to reach the final decision. Close

• 4. [Article] The Effects of Roadway Capacity on Peak Narrowing - Evidence from 1995 NPTS

  Spreading of the peak is one effect of increased peak-period congestion. Due to peak spreading, the travel-time impact of congestion is mitigated for some travelers, but the inconvenience of traveling ...

  Citation × Citation Citation Abstract Copy Title: The Effects of Roadway Capacity on Peak Narrowing - Evidence from 1995 NPTS Author: Zhang, Jihong, Rufolo, Anthony M., Dueker, Kenneth, Strathman, James G. Year: 2000 Spreading of the peak is one effect of increased peak-period congestion. Due to peak spreading, the travel-time impact of congestion is mitigated for some travelers, but the inconvenience of traveling at a less-preferred time also has a cost. Alternatively, increases in capacity have their impacts on peak-period congestion mitigated by a narrowing of the peak. This reduces the travel-time savings, but it generates a benefit for those traveling closer to their preferred times. This benefit from capacity improvements has largely been ignored, and one reason is the difficulty of quantifying the effect. This paper reports on some crude attempts to quantify the peak-narrowing effect of increased capacity. Using 1995 Nationwide Personal Transportation Survey (NPTS) data, this study investigates how workers in Metropolitan Statistical Areas (MSAs) in the US respond to roadway capacity differences in terms of changing their departure time to work. It is assumed that there is some distribution of travel times given by a mean and some measure of deviation from the mean. Peak narrowing is then measured by decreases in the deviation from the mean. The peak narrowing effects are modeled for both the morning commute and all departures from home for work at any time of the day. As expected, in urban areas with higher roadway capacity per capita, workers tend to depart from home closer to the peak time. For the morning commute, the model estimates that each one-percent increase in lane-miles per capita results in workers departing from home about 5.75 percent closer to the peak time. The effects of roadway capacity are found to be statistically significant in both models. Title: The Effects of Roadway Capacity on Peak Narrowing - Evidence from 1995 NPTS Author: Zhang, Jihong, Rufolo, Anthony M., Dueker, Kenneth, Strathman, James G. Year: 2000 Spreading of the peak is one effect of increased peak-period congestion. Due to peak spreading, the travel-time impact of congestion is mitigated for some travelers, but the inconvenience of traveling at a less-preferred time also has a cost. Alternatively, increases in capacity have their impacts on peak-period congestion mitigated by a narrowing of the peak. This reduces the travel-time savings, but it generates a benefit for those traveling closer to their preferred times. This benefit from capacity improvements has largely been ignored, and one reason is the difficulty of quantifying the effect. This paper reports on some crude attempts to quantify the peak-narrowing effect of increased capacity. Using 1995 Nationwide Personal Transportation Survey (NPTS) data, this study investigates how workers in Metropolitan Statistical Areas (MSAs) in the US respond to roadway capacity differences in terms of changing their departure time to work. It is assumed that there is some distribution of travel times given by a mean and some measure of deviation from the mean. Peak narrowing is then measured by decreases in the deviation from the mean. The peak narrowing effects are modeled for both the morning commute and all departures from home for work at any time of the day. As expected, in urban areas with higher roadway capacity per capita, workers tend to depart from home closer to the peak time. For the morning commute, the model estimates that each one-percent increase in lane-miles per capita results in workers departing from home about 5.75 percent closer to the peak time. The effects of roadway capacity are found to be statistically significant in both models. Close

• 5. [Article] Political Performance, Leadership, and Regional Integration in Europe: An Examination of the French and German Roles

  Prior research on a regional leader’s role in the deepening of regional integration assumes that economic power translates directly into political capabilities. Relative political capacity among states ...

  Citation × Citation Citation Abstract Copy Title: Political Performance, Leadership, and Regional Integration in Europe: An Examination of the French and German Roles Author: Genna, Gaspare M., Yesilada, Birol, Noordijk, Peter Andrew Year: 2013 Prior research on a regional leader’s role in the deepening of regional integration assumes that economic power translates directly into political capabilities. Relative political capacity among states is central to the creation and deepening of regional integration since it is this capacity that smoothes out the transition from a closed to an open economy. Should a state have low levels of this capacity but desire openness, it will partner with regional leaders given the leaders’ higher relative political capacity. However, the leaders’ subsidy of a partner’s capacity comes at a price. The leaders would trade political capacity for forming a regional bloc along its preferences. A partner will join with a regional leader so long as it is satisfied with the leaders’ preferences. By doing so, it reduces the cost of the subsidy. Our analysis of European integration indicates that French and German relative political capacities are an important factor in the continent’s unifying efforts by conditioning institutional homogeneity and capital stocks mobility, both of which are critical for political and economic union. However, the German effect contrasts with the French effect in that we discover greater German effectiveness in mitigating potential barriers to integration. Title: Political Performance, Leadership, and Regional Integration in Europe: An Examination of the French and German Roles Author: Genna, Gaspare M., Yesilada, Birol, Noordijk, Peter Andrew Year: 2013 Prior research on a regional leader’s role in the deepening of regional integration assumes that economic power translates directly into political capabilities. Relative political capacity among states is central to the creation and deepening of regional integration since it is this capacity that smoothes out the transition from a closed to an open economy. Should a state have low levels of this capacity but desire openness, it will partner with regional leaders given the leaders’ higher relative political capacity. However, the leaders’ subsidy of a partner’s capacity comes at a price. The leaders would trade political capacity for forming a regional bloc along its preferences. A partner will join with a regional leader so long as it is satisfied with the leaders’ preferences. By doing so, it reduces the cost of the subsidy. Our analysis of European integration indicates that French and German relative political capacities are an important factor in the continent’s unifying efforts by conditioning institutional homogeneity and capital stocks mobility, both of which are critical for political and economic union. However, the German effect contrasts with the French effect in that we discover greater German effectiveness in mitigating potential barriers to integration. Close

• 6. [Article] Rooftop PV Impacts on Fossil Fuel Electricity Generation and CO2 Emissions in the Pacific Northwest

  This thesis estimates the impacts of rooftop photovoltaic (PV) capacity on electricity generation and CO2 emissions in America's Pacific Northwest. The region's demand for electricity is increasing at ...

  Citation × Citation Citation Abstract Copy Title: Rooftop PV Impacts on Fossil Fuel Electricity Generation and CO2 Emissions in the Pacific Northwest Author: Weiland, Daniel Albert Year: 2013 This thesis estimates the impacts of rooftop photovoltaic (PV) capacity on electricity generation and CO2 emissions in America's Pacific Northwest. The region's demand for electricity is increasing at the same time that it is attempting to reduce its greenhouse gas emissions. The electricity generated by rooftop PV capacity is expected to displace electricity from fossil fueled electricity generators and reduce CO2 emissions, but when and how much? And how can this region maximize and focus the impacts of additional rooftop PV capacity on CO2 emissions? To answer these questions, an hourly urban rooftop PV generation profile for 2009 was created from estimates of regional rooftop PV capacity and solar resource data. That profile was compared with the region's hourly fossil fuel generation profile for 2009 to determine how much urban rooftop PV generation reduced annual fossil fuel electricity generation and CO2 emissions. Those reductions were then projected for a range of additional multiples of rooftop PV capacity. The conclusions indicate that additional rooftop PV capacity in the region primarily displaces electricity from natural gas generators, and shows that the timing of rooftop PV generation corresponds with the use of fossil fuel generators. Each additional Wp/ capita of rooftop PV capacity reduces CO2 emissions by 9,600 to 7,300 tons/ year. The final discussion proposes some methods to maximize and focus rooftop PV impacts on CO2 emissions, and also suggests some questions for further research. Title: Rooftop PV Impacts on Fossil Fuel Electricity Generation and CO2 Emissions in the Pacific Northwest Author: Weiland, Daniel Albert Year: 2013 This thesis estimates the impacts of rooftop photovoltaic (PV) capacity on electricity generation and CO2 emissions in America's Pacific Northwest. The region's demand for electricity is increasing at the same time that it is attempting to reduce its greenhouse gas emissions. The electricity generated by rooftop PV capacity is expected to displace electricity from fossil fueled electricity generators and reduce CO2 emissions, but when and how much? And how can this region maximize and focus the impacts of additional rooftop PV capacity on CO2 emissions? To answer these questions, an hourly urban rooftop PV generation profile for 2009 was created from estimates of regional rooftop PV capacity and solar resource data. That profile was compared with the region's hourly fossil fuel generation profile for 2009 to determine how much urban rooftop PV generation reduced annual fossil fuel electricity generation and CO2 emissions. Those reductions were then projected for a range of additional multiples of rooftop PV capacity. The conclusions indicate that additional rooftop PV capacity in the region primarily displaces electricity from natural gas generators, and shows that the timing of rooftop PV generation corresponds with the use of fossil fuel generators. Each additional Wp/ capita of rooftop PV capacity reduces CO2 emissions by 9,600 to 7,300 tons/ year. The final discussion proposes some methods to maximize and focus rooftop PV impacts on CO2 emissions, and also suggests some questions for further research. Close

• 7. [Article] Bicycle Level of Service: Where are the Gaps in Bicycle Flow Measures?

  Bicycle use is increasing in many parts of the U.S. Local and regional governments have set ambitious bicycle mode share goals as part of their strategy to curb greenhouse gas emissions and relieve traffic ...

  Citation × Citation Citation Abstract Copy Title: Bicycle Level of Service: Where are the Gaps in Bicycle Flow Measures? Author: Johnson, Pamela Christine Year: 2014 Bicycle use is increasing in many parts of the U.S. Local and regional governments have set ambitious bicycle mode share goals as part of their strategy to curb greenhouse gas emissions and relieve traffic congestion. In particular, Portland, Oregon has set a 25% mode share goal for 2030 (PBOT 2010). Currently bicycle mode share in Portland is 6.1% of all trips. Other cities and regional planning organizations are also setting ambitious bicycle mode share goals and increasing bicycle facilities and programs to encourage bicycling. Increases in bicycle mode share are being encouraged to increase. However, cities with higher-than-average bicycle mode share are beginning to experience locations with bicycle traffic congestion, especially during peak commute hours. Today, there are no established methods are used to describe or measure bicycle traffic flows. In the 1960s, the Highway Capacity Manual (HCM) introduced Level of Service (LOS) measurements to describe traffic flow and capacity of motor vehicles on highways using an A-to-F grading system; "A" describes free flow traffic with no maneuvering constraints for the driver and an "F" grade corresponds to over capacity situations in which traffic flow breaks down or becomes "jammed". LOS metrics were expanded to highway and road facilities, operations and design. In the 1990s, the HCM introduced LOS measurements for transit, pedestrians, and bicycles. Today, there are many well established and emerging bicycle level of service (BLOS) methods that measure the stress, comfort and perception of safety of bicycle facilities. However, it was been assumed that bicycle traffic volumes are low and do not warrant the use of a LOS measure for bicycle capacity and traffic flow. There are few BLOS methods that take bicycle flow into consideration, except for in the case of separated bicycle and bicycle-pedestrian paths. This thesis investigated the state of BLOS capacity methods that use bicycle volumes as a variable. The existing methods were applied to bicycle facility elements along a corridor that experiences high bicycle volumes in Portland, Oregon. Using data from the study corridor, BLOS was calculated and a sensitivity analysis was applied to each of the methods to determine how sensitive the models are to each of the variables used. An intercept survey was conducted to compare the BLOS capacity scores calculated for the corridor with the users' perception. In addition, 2030 bicycle mode share for the study corridor was estimated and the implications of increased future bicycle congestion were discussed. Gaps in the BLOS methods, limitations of the thesis study and future research were summarized. In general, the existing methods for BLOS capacity are intended for separated paths; they are not appropriate for existing high traffic flow facilities. Most of the BLOS traffic flow methods that have been developed are most sensitive to bicycle volumes. Some of these models may be a good starting point to improve BLOS capacity and traffic flow measures for high bicycle volume locations. Without the tools to measure and evaluate the patterns of bicycle capacity and traffic flow, it will be difficult to monitor and mitigate bicycle congestion and to plan for efficient bicycle facilities in the future. This report concludes that it is now time to develop new BLOS capacity measures that address bicycle traffic flow. Title: Bicycle Level of Service: Where are the Gaps in Bicycle Flow Measures? Author: Johnson, Pamela Christine Year: 2014 Bicycle use is increasing in many parts of the U.S. Local and regional governments have set ambitious bicycle mode share goals as part of their strategy to curb greenhouse gas emissions and relieve traffic congestion. In particular, Portland, Oregon has set a 25% mode share goal for 2030 (PBOT 2010). Currently bicycle mode share in Portland is 6.1% of all trips. Other cities and regional planning organizations are also setting ambitious bicycle mode share goals and increasing bicycle facilities and programs to encourage bicycling. Increases in bicycle mode share are being encouraged to increase. However, cities with higher-than-average bicycle mode share are beginning to experience locations with bicycle traffic congestion, especially during peak commute hours. Today, there are no established methods are used to describe or measure bicycle traffic flows. In the 1960s, the Highway Capacity Manual (HCM) introduced Level of Service (LOS) measurements to describe traffic flow and capacity of motor vehicles on highways using an A-to-F grading system; "A" describes free flow traffic with no maneuvering constraints for the driver and an "F" grade corresponds to over capacity situations in which traffic flow breaks down or becomes "jammed". LOS metrics were expanded to highway and road facilities, operations and design. In the 1990s, the HCM introduced LOS measurements for transit, pedestrians, and bicycles. Today, there are many well established and emerging bicycle level of service (BLOS) methods that measure the stress, comfort and perception of safety of bicycle facilities. However, it was been assumed that bicycle traffic volumes are low and do not warrant the use of a LOS measure for bicycle capacity and traffic flow. There are few BLOS methods that take bicycle flow into consideration, except for in the case of separated bicycle and bicycle-pedestrian paths. This thesis investigated the state of BLOS capacity methods that use bicycle volumes as a variable. The existing methods were applied to bicycle facility elements along a corridor that experiences high bicycle volumes in Portland, Oregon. Using data from the study corridor, BLOS was calculated and a sensitivity analysis was applied to each of the methods to determine how sensitive the models are to each of the variables used. An intercept survey was conducted to compare the BLOS capacity scores calculated for the corridor with the users' perception. In addition, 2030 bicycle mode share for the study corridor was estimated and the implications of increased future bicycle congestion were discussed. Gaps in the BLOS methods, limitations of the thesis study and future research were summarized. In general, the existing methods for BLOS capacity are intended for separated paths; they are not appropriate for existing high traffic flow facilities. Most of the BLOS traffic flow methods that have been developed are most sensitive to bicycle volumes. Some of these models may be a good starting point to improve BLOS capacity and traffic flow measures for high bicycle volume locations. Without the tools to measure and evaluate the patterns of bicycle capacity and traffic flow, it will be difficult to monitor and mitigate bicycle congestion and to plan for efficient bicycle facilities in the future. This report concludes that it is now time to develop new BLOS capacity measures that address bicycle traffic flow. Close

• 8. [Article] Building Bridges with Social Capital in the European Union

  A culture of accommodation and tolerance is a necessary part of establishing and preserving a functional multi-national and multi-ethnic European Union. Civil society organizations and their associated ...

  Citation × Citation Citation Abstract Copy Title: Building Bridges with Social Capital in the European Union Author: Noordijk, Peter Andrew Year: 2013 A culture of accommodation and tolerance is a necessary part of establishing and preserving a functional multi-national and multi-ethnic European Union. Civil society organizations and their associated social capital have been shown to foster civic capacity and achievement of public policy goals. However, social capital that is based on group identity can also contribute to a sense of intolerance towards out-groups, undermining the stated tolerance objectives of the social pillar of the European Union. States with a strong presence alongside civil society are expected to be curb the development of the exclusionary bonding form of social capital in favor of bridging social capital which will improve progress toward policy goals. This study tests the link between government capacity, social capital and tolerance using data from the 1990-2009 waves of the World Values Survey and European Values Study. Using path analysis and multi-level models of the relationships between political capacity, social capital and intolerance, the model establishes that government capacity enhances bridging social capital and which increases social tolerance. The study fills a gap in understanding how government capacity and policy can result in improved social capital even with greater diversity. A proposed relationship between political capacity and bonding forms of social capital was not supported. Title: Building Bridges with Social Capital in the European Union Author: Noordijk, Peter Andrew Year: 2013 A culture of accommodation and tolerance is a necessary part of establishing and preserving a functional multi-national and multi-ethnic European Union. Civil society organizations and their associated social capital have been shown to foster civic capacity and achievement of public policy goals. However, social capital that is based on group identity can also contribute to a sense of intolerance towards out-groups, undermining the stated tolerance objectives of the social pillar of the European Union. States with a strong presence alongside civil society are expected to be curb the development of the exclusionary bonding form of social capital in favor of bridging social capital which will improve progress toward policy goals. This study tests the link between government capacity, social capital and tolerance using data from the 1990-2009 waves of the World Values Survey and European Values Study. Using path analysis and multi-level models of the relationships between political capacity, social capital and intolerance, the model establishes that government capacity enhances bridging social capital and which increases social tolerance. The study fills a gap in understanding how government capacity and policy can result in improved social capital even with greater diversity. A proposed relationship between political capacity and bonding forms of social capital was not supported. Close

• 9. [Article] Variation in Green Roof Storage Capacity, Associated Drivers, and Implications for Stormwater Management in Portland, Oregon

  Greens roofs, also known as ecoroofs or living roofs, provide numerous ecosystem services and are becoming widely integrated into urban stormwater management systems. Despite a long and robust history ...

  Citation × Citation Citation Abstract Copy Title: Variation in Green Roof Storage Capacity, Associated Drivers, and Implications for Stormwater Management in Portland, Oregon Author: Estrella, Melecio Year: 2016 Greens roofs, also known as ecoroofs or living roofs, provide numerous ecosystem services and are becoming widely integrated into urban stormwater management systems. Despite a long and robust history of green roof projects in Portland, Oregon, there is a distinct lack of research on in situ performance. This thesis addressed this gap by investigating the hydrologic performance of five green roofs in Portland for a time period spanning November through February. Despite difficulty with the sensor calibrations, our analysis of moisture content data from these roofs revealed variation in: (1) total evapotranspiration, which serves as a proxy for total stormwater retention, and (2) storage capacity, which was defined as the difference between average maximum and minimum substrate volumetric water content measured under field conditions. Evapotranspiration was predicted by storage capacity following first order growth using non-linear regression analysis, suggesting that increasing storage capacity should correspond with increases in evapotranspiration and retention up until an inflection point of possibly 8-9mm beyond which the effect diminishes. Storage capacity was further shown to be correlated with substrate properties such as organic matter content and coefficient of curvature. Finally, retention values of 13.4% - 32.8% for Portland’s rainy season in 2015-2016 were found to be substantially lower than optimal annual values reported in other studies in Portland as well as cities around the world. This suggests that Portland’s green roofs may not perform as well as expected during months of high precipitation, which are the times when hydrologic performance is most critical. Further research should consider seasonal green roof performance in the Pacific Northwest and also revisit storage capacity as a parameter to include in future design standards. Title: Variation in Green Roof Storage Capacity, Associated Drivers, and Implications for Stormwater Management in Portland, Oregon Author: Estrella, Melecio Year: 2016 Greens roofs, also known as ecoroofs or living roofs, provide numerous ecosystem services and are becoming widely integrated into urban stormwater management systems. Despite a long and robust history of green roof projects in Portland, Oregon, there is a distinct lack of research on in situ performance. This thesis addressed this gap by investigating the hydrologic performance of five green roofs in Portland for a time period spanning November through February. Despite difficulty with the sensor calibrations, our analysis of moisture content data from these roofs revealed variation in: (1) total evapotranspiration, which serves as a proxy for total stormwater retention, and (2) storage capacity, which was defined as the difference between average maximum and minimum substrate volumetric water content measured under field conditions. Evapotranspiration was predicted by storage capacity following first order growth using non-linear regression analysis, suggesting that increasing storage capacity should correspond with increases in evapotranspiration and retention up until an inflection point of possibly 8-9mm beyond which the effect diminishes. Storage capacity was further shown to be correlated with substrate properties such as organic matter content and coefficient of curvature. Finally, retention values of 13.4% - 32.8% for Portland’s rainy season in 2015-2016 were found to be substantially lower than optimal annual values reported in other studies in Portland as well as cities around the world. This suggests that Portland’s green roofs may not perform as well as expected during months of high precipitation, which are the times when hydrologic performance is most critical. Further research should consider seasonal green roof performance in the Pacific Northwest and also revisit storage capacity as a parameter to include in future design standards. Close

• 10. [Article] Model for Network Assignment Problem of Capacitated Freight with Disruptions

  A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability ...

  Citation × Citation Citation Abstract Copy Title: Model for Network Assignment Problem of Capacitated Freight with Disruptions Author: Figliozzi, Miguel, Unnikrishnan, Avinash, Shahabi, Mehrdad Year: 2012 A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability of a user to reconsider and adapt his or her routing decisions in response to newly acquired information about network disruption. When real-time tracking and monitoring of network shipments allow companies a routing recourse, network capacity must be simultaneously considered. If a disruption significantly alters network flows, the capacity of alternative or secondary routes may be quickly reached. A new freight mathematical model with a capacitated network and adaptive routing was developed and solved. Results showed that simultaneous consideration of recourse and capacity constraints was superior to benchmark results obtained with nonadaptive deterministic behavior. Title: Model for Network Assignment Problem of Capacitated Freight with Disruptions Author: Figliozzi, Miguel, Unnikrishnan, Avinash, Shahabi, Mehrdad Year: 2012 A modeling framework is proposed for the freight network assignment problem with recourse, network travel time and cost disruptions, and link flow capacity constraints. "Recourse" is defined as the ability of a user to reconsider and adapt his or her routing decisions in response to newly acquired information about network disruption. When real-time tracking and monitoring of network shipments allow companies a routing recourse, network capacity must be simultaneously considered. If a disruption significantly alters network flows, the capacity of alternative or secondary routes may be quickly reached. A new freight mathematical model with a capacitated network and adaptive routing was developed and solved. Results showed that simultaneous consideration of recourse and capacity constraints was superior to benchmark results obtained with nonadaptive deterministic behavior. Close