Post-Silicon validation is playing an increasingly important role as more chips are failing in the functional mode due to either manufacturing defects escaped during scan-based tests or design bugs missed during pre-silicon validation. Critical to the diagnosis engineer is the ability to observe as many relevant internal signal values as possible during debug. To do so, trace buffers have been proposed for enhancing the observability of internal signals during post-silicon debug. Trace Buffers are used to trace (record the values of) the internal signals in real-time when chip is in its normal operation. However, existing trace buffer architectures trace very few signals for a large number of cycles. Thus, even with a good subset of signals traced, one often still cannot restore all the relevant values in the circuit. In this work, we propose two different flexible trace buffer architectures that can restore the values for all signals by making the trace signals configurable. In addition, the buffer space can also be shared among different traced signals which makes the architectures highly flexible. As compared to conventional trace buffer architectures, the new architectures have comparable area overhead but offer the ability to restore all signals in the circuit. For cases of less than 100% restoration, the ability of circuit invariants to improve the signal restoration is explored. A promising direction for the future work is provided where targeted invariants may lead to better restoration scenario during post-silicon validation. / Master of Science

Excess nutrient pollution and eutrophication are widespread problems that must be solved at watershed scales, and stream restoration is increasingly implemented as a solution. Yet few studies evaluate the cumulative effects of multiple individual restoration projects on watershed-scale nutrient loading. We constructed a HEC-RAS model of stream restoration implemented throughout a generic 4th order watershed typical of the Piedmont physiographic province of the eastern USA. We simulated restoration of hyporheic exchange as one increasingly popular technique that receives dissolved nitrate-nitrogen (NO3--N) mitigation credit under the Chesapeake Bay TMDL. We populated the model with hyporheic exchange (0.3% of surface flow per hyporheic-exchange inducing in-stream restoration structure) and NO3--N removal (supply-limited denitrification removes all NO3--N that enters the hyporheic zone) values from prior literature on in-stream structures and related restoration techniques. We then varied the percentage of stream channels in the watershed in which restoration occurred. For watersheds with less than 100% of stream channels restored, we also varied where in the watershed (i.e. stream order) that restoration occurred. We found that hyporheic restoration in our 4th order watersheds has the potential to reduce NO3--N loading to downstream waterbodies by up to 83%, but that a maximum of <100% reduction exists given certain watershed characteristics. Model results revealed a nonlinear relationship between percent of stream channels restored and percent NO3--N loading reduction that occurred at the watershed outlet. This indicates that the effects of individual projects are not linearly additive, and must be evaluated in the context of how much of the watershed has already been restored. We also found that restoration was more effective at reducing NO3--N loading when it occurred in higher order streams (e.g., 3rd and 4th order), yielding load reductions upward of 30% compared to < 10% in lower order streams (e.g., 1st and 2nd order). Thus, the location of an individual restoration project within a watershed is important in determining its effect on NO3--N. Overall, our results indicate that hyporheic restoration can have significant effects on watershed NO3--N loading to downstream waterbodies, yet the watershed must be viewed as a whole to understand the potential impacts of any particular project under consideration. / Master of Science / Nutrient pollution and harmful algal blooms are widespread problems that must be solved at watershed scales, and stream restoration is increasingly implemented as a solution. Yet few studies evaluate the cumulative effects of multiple individual restoration projects on watershed-scale nutrient loading. We constructed a HEC-RAS model of stream restoration implemented throughout a generic watershed typical of the mid-Atlantic USA. We simulated restoration of nutrient-reducing groundwater flow cells along a stream corridor (hyporheic exchange) as one increasingly popular technique that is emphasized under the Chesapeake Bay TMDL. We populated the model with hyporheic exchange and nitrate-nitrogen (NO3--N) removal values from prior literature on in-stream structures and related restoration techniques. We then varied the percentage of stream channels in the watershed in which restoration occurred. For watersheds with less than 100% of stream channels restored, we also varied where in the watershed (i.e. stream order) that restoration occurred. We found that hyporheic restoration in our watershed has the potential to reduce NO3--N loading to downstream waterbodies by up to 83%, but that a maximum of less than 100% reduction exists given certain watershed characteristics. Model results revealed a nonlinear relationship between percent of stream channels restored and percent NO3--N load reduction that occurred at the watershed outlet. This indicates that the effects of individual projects are not linearly additive, and must be evaluated in the context of how much of the watershed has already been restored. We also found that restoration was more effective at reducing NO3--N loading when it occurred in larger streams, yielding load reductions upward of 30% compared to less than 10% in smaller streams. Thus, the location of an individual restoration project within a watershed is important in determining its effect on NO3--N. Understanding the maximum possible degree of NO3--N reducing hyporheic exchange is an important step for practitioners and policy-makers in choosing the most effective location for a stream restoration based on a project's goals, and cannot be done without analyzing the watershed as a whole. With more watershed-scale planning and a better understanding of certain physical characteristics, we can choose restoration locations and strategies that will ultimately work more efficiently toward reaching a nutrient reduction goal.

As a response to rising wildfire hazard and forest structure and composition concerns, the National Fire and Fire Surrogate Study was established in 2000 to determine how fuel reduction and ecosystem restoration techniques might affect ecosystem properties and processes across the United States. Soil chemistry and the southern Appalachian Mountains were an ecosystem property and ecoregion of interest, respectively. Treatments utilized at this site included: prescribed fire alone (3 burns), mechanical cutting of understory shrubs and midstory trees alone (2 cuttings), and a combination of the two (2 installations). Soils were sampled in 2018 to determine potential treatment impacts for: O horizon and mineral soil (0-10 cm depth) carbon (C), nitrogen (N), carbon:nitrogen (C:N) and mineral soil calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), and pH. Results suggested slight, but statistically significant changes in O horizon C and N and mineral soil C, N, C:N, Ca, and P values from 2001-2018 differed statistically between the treatments. Soil responses differed significantly between the replications utilized in this study and also did not fully agree with results from previous sampling that occurred following the first implementation of these treatments. This research highlights the spatial and temporal nature of soil responses to management. When considered with previously reported vegetation and fuels results from this site, it appeared that prescribed burning with and without mechanical cutting presented the most promise to achieve ecosystem restoration and fuel reduction properties without altering forest soil chemistry. / Master of Science / Fire was historically present in the southern Appalachian Mountains from both natural and anthropogenic sources. A common natural cause resulted from lightning ignitions while some common anthropogenic sources resulted from Native American ignitions. Their fire-use goals included understory clearing, reduction of pests and diseases, hunting, and even warfare. These practices were adopted by early European settlers and were implemented regularly across the landscape through the late 19th century. In the early 20th century, however, fire exclusion policies were implemented across broad acreages of the continental United States. Over 80 years later, such policies led to forests that have been altered from their historic composition. Some of these alterations include changes to plant species composition. In portions of eastern United States forests, fire intolerant, shade tolerant species now exert a dominant influence beyond what would be expected in a frequently altered state. This process, referred to as mesophication, is a positive-feedback cycle that changes the composition of the forest floor, as well, as a result of the vegetative composition alterations. This cycle has led to substantial forest floor fuel accumulations comprised of vegetative litter and duff. Essentially, this policy shift and subsequent fuel alteration has potentially increased wildfire hazard when dry weather conditions and ignitions coalesce. In 2000, the National Fire and Fire Surrogate Study (FFSS) was designed and implemented to study ecosystem responses to fuel reduction treatments in 13 locations across the United States. One of these locations was the southern Appalachian Mountains near Hendersonville, North Carolina. For this particular study, soil chemistry was the observed ecosystem trait. The treatments included untreated control, prescribed fire, mechanical cutting of vegetation, and a combination of prescribed fire and cutting. From 2001-2018, 4 prescribed burns, 2 cutting treatments, and 2 combination treatments have been implemented. Prior to the first treatments in 2001, soils were sampled to determine pre-treatment soil chemistry. In 2018, soils were re-sampled to determine the potential long-term impacts of repeated implementations of these management techniques on forest soil chemistry. Overall, the results suggested that forest soil chemistry was altered in ways that do not appear biologically significant and may in fact fail to alter soils in ways that might benefit and sustain long-term ecological restoration objectives. Continued treatment applications may be necessary to obtain more desirable conditions.

Several Municipalities in Virginia are currently developing and implementing watershed programs. While programmatic goals and objectives vary, all seek to incorporate stream restoration project work. Decision support tools exist for many aspects of watershed and water resources management, however, there are currently no such tools to aid municipalities in their stream restoration efforts. This study details the development of such a decision support tool for the Henrico County Stream Assessment/Watershed Management Program based on the assessment of stream restoration opportunities and feasibility constraints. A framework for the development of future municipal watershed programs is presented and related issues are discussed. / Master of Landscape Architecture

This thesis presents recommendations for controlling quality in structural interventions on historic properties. Recognizing that establishing quality in the early stages of an intervention can set the standard of quality for an entire project, these recommendations are for the first phase of an intervention, the Pre-Construction Phase. To create these recommendations, first a literature review of past and present intervention methods is conducted. After breaking down the Pre-Construction Phase first into a series of steps, and then each step into a series of details, a standard of quality is established for each detail. The available methods for conducting each detail are then analyzed. Using the literature review and the established standards of quality, recommendations are made as to which method is most appropriate for a given project. These recommendations are applied to two case studies, the structural interventions of Boykin's Tavern and Fallingwater. Finally, conclusions on the use of the proposed quality control recommendations are drawn, and suggestions are given for further work in this field. / Master of Science

Oaks (Quercus spp.) are an important part of the forested landscape in the eastern United States. Although oak is increasing in standing volume, an oak regeneration bottleneck has occurred throughout its range in recent decades. Subsequently, as oak overstory is being harvested, rarely is oak recruited into the overstory to maintain the historic dominance of overstory oak. In the absence of fire and subsequent canopy closure, mesic species have proliferated, frequently forming a dense understory, inhibiting oak regeneration success. This study was developed to determine species dynamics between oak and oak competitors in response to silvicultural treatments in the southern Appalachian Mountains of North Carolina. The treatments were: a shelterwood treatment (25-30% basal area reduction through mid-story removal with herbicides), a prescribed fire treatment (two late dormant season fires occurred over a 9-year period), a shelterwood and burn treatment (prescribed fire 3-5 years following 30-40% basal area removal), and an unmanaged control. To determine treatment impacts on the regeneration layer, importance value and stems ha-1 were calculated at the species group and individual species level 0- and 9- years post initial treatment. A principal component analysis and an analysis of basal area by treatment 0- and 9-years post-treatment were used to determine the influence of site-specific characteristics on regeneration layer response. The greatest relative increases in importance values were 1401% and 2995% for the red oak group and yellow-poplar (Liriodendron tulipifera), respectively, in the shelterwood and burn (SWB). Change in all species groups were predominantly influenced by the smallest size-class (<0.6 m tall), with the exception of northern red oak (Q. rubra) and yellow-poplar in the SWB. The SWB significantly reduced importance values of all shade tolerant species groups and was the only treatment to decrease red maple (Acer rubrum) importance value and density over the study years. The prescribed fire (RXF) treatment increased red oak group importance value, while simultaneously decreasing yellow-poplar importance value and increasing red maple importance value. Changes in the red oak group in the SWB and the RXF were driven by northern red oak and scarlet oak (Q. coccinea), respectively. Treatments do not appear to change the competitive status of the white oak group. Elevation was closely associated with the red oak group. Yellow-poplar importance value increases, white oak group importance value increases, and site index were closely associated. Decreases in basal area were greatest in the SWB, and the SWB was the only treatment to significantly decrease overstory basal area. The RXF and SWB treatments improved the competitive status of only some oak species, but modifications to these treatments may result in better control of yellow-poplar and red maple competition, further improving oak's competitive status. Site specific factors such as elevation and site index may have impacted the regeneration layer response to treatments. / Master of Science / Oak-hickory (Quercus and Carya spp.) and oak-pine (Quercus and Pinus spp.) forest types occupy approximately 57 million and 11 million hectares of forestland in the eastern United States, respectively. Oaks are considered ecological and economic keystone species throughout the eastern U.S and maintenance of this genus in eastern U.S. forests has been a primary regional focus for decades. Historic disturbance regimes are estimated to have been much different than they are today. Fire was a common disturbance mechanism prior to fire suppression in the early 20th century. Frequent fires maintained much of the oak component historically. In the absence of fire, the species found in the understories of mature oak stands are commonly mesophytic species, such as yellow-poplar (Liriodendron tulipifera L.) and red maple (Acer rubrum L.). Over the last several decades, research has been conducted to investigate the impacts of treatments targeting the promotion of oak regeneration, but results have been varied and valuable long-term studies are rare. To determine the effects of treatments on the regeneration dynamics of oak and its competitors, four treatments were compared in the southern Appalachian Mountains. Treatments included a control, shelterwood harvest (SW), prescribed fire (RXF), and a shelterwood and burn (SWB). Stand structure and composition were monitored over a 9-year period post-treatment. Overall, results indicate the shelterwood and burn treatment has the greatest potential to improve the competitiveness of the red oak group in the regeneration layer, but yellow-poplar competition in the shelterwood and burn will need be addressed, considering its large increases in this treatment. Although increases in the red oak group were not as great as increases in the RXF treatment compared with the SWB, fire does show promise as a method to increase oak regeneration success. Changes in red oak group importance value varied with elevation, emphasizing results of treatments can be affected by site characteristics. Treatments were not successful at enhancing the competitive status of white oak (Quercus alba L.). Silvicultural treatments can be used to improve the competitive status of oak on sites in the southern Appalachian Mountains, but close monitoring of species dynamics throughout the rotation are needed to ensure long-term oak success.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

published_or_final_version / abstract / Conservation / Master / Master of Science in Conservation

published_or_final_version / Urban Planning and Environmental Management / Master / Master of Science in Urban Planning

1. Realigning rivers is becoming common as a solution to conflicting needs of land development and ecosystem preservation. Although an increasing number of projects are monitored, exactly how these channels develop as functional stream ecosystems is still poorly understood. Mining in the upper catchment of the River Nith (Scotland) required the realignment of 3km (approx.) of river. The engineered channel was designed around sound geomorphological principles of sediment transport and supply with a sinuous planform and pool-riffle sequences along the installed gravel-bed. 2. A comprehensive survey covering biotic and abiotic development was devised and implemented to test models and hypotheses relating to the development riverine habitats over the first three years. 2. Physical habitat development at the reach scale was investigated using fixed-point photography and differential GPS surveys of the thalweg and of cross-sectional form every 100m. This revealed the development of a relatively diverse streambed habitat in response to both the channel slope and planform. However, other than at meander bends where asymmetry developed over several years, little change was observed to the form of the engineered riverbanks. 3. Kick-net surveys of benthic invertebrate communities at 10 sites showed a negative relationship between specific measures of diversity and downstream distance during the early stages of development. (e.g. Richness with chainage at the 6 month stage) but the relationship degrades rapidly and is likely in part to appear as a result of low population densities. 4. Survey of transects through the riparian zone perpendicular to the river indicated that colonisation by vegetation is also related to distance along the realignment but physical habitat and geographical factors play a more dominant role over development (Canonical correspondence analysis of vegetation data in 2007) 5. Many of the indices of diversity for both biotic and abiotic elements of the ecosystem proved ineffective at detecting development at the reach scale. This may be because significant changes occur at a smaller scale than was detected by the surveys. It is likely that greater resolution is required to detect more ecologically meaningful relationships and patterns. 6. Overall study shows constructed realignments can rapidly develop a diverse streambed community within 24 months. Riparian communities are slower to develop because of the slow development of riverbank habitat diversity. Other ecosystem properties such as resilience and connectivity may take much longer.