The main study objective was to develop robust processing and analysis techniques to facilitate the use of small-footprint lidar data for estimating forest biophysical parameters measuring individual trees identifiable on the three-dimensional lidar surface. This study derived the digital terrain model from lidar data using an iterative slope-based algorithm and developed processing methods for directly measuring tree height, crown diameter, and stand density. The lidar system used for this study recorded up to four returns per pulse, with an average footprint of 0.65 m and an average distance between laser shots of 0.7 m. The lidar data set was acquired over deciduous, coniferous, and mixed stands of varying age classes and settings typical of the southeastern United States (37° 25' N, 78° 41' W). Lidar processing techniques for identifying and measuring individual trees included data fusion with multispectral optical data and local filtering with both square and circular windows of variable size. The window size was based on canopy height and forest type. The crown diameter was calculated as the average of two values measured along two perpendicular directions from the location of each tree top, by fitting a four-degree polynomial on both profiles. The ground-truth plot design followed the U.S. National Forest Inventory and Analysis (FIA) field data layout. The lidar-derived tree measurements were used with regression models and cross-validation to estimate plot level field inventory data, including volume, basal area, and biomass. FIA subplots of 0.017 ha each were pooled together in two categories, deciduous trees and pines. For the pine plots, lidar measurements explained 97% of the variance associated with the mean height of dominant trees. For deciduous plots, regression models explained 79% of the mean height variance for dominant trees. Results for estimating crown diameter were similar for both pines and deciduous trees, with R2 values of 0.62-0.63 for the dominant trees. R2 values for estimating biomass were 0.82 for pines (RMSE 29 Mg/ha) and 0.32 for deciduous (RMSE 44 Mg/ha). Overall, plot level tree height and crown diameter calculated from individual tree lidar measurements were particularly important in contributing to model fit and prediction of forest volume and biomass. / Ph. D.

Based upon the principles of equality, respect, and dignity for an organization and its community, Robert K. Greenleaf (1977) dedicated his life to conceptualizing and defining the humanistic philosophy of "servant leadership." With service and leadership sometimes seen as opposites, servant leaders are often misunderstood and perhaps underestimated. The purpose of this study was to create a well-defined comprehensive portrait of a servant leader by identifying key descriptors of the characteristics and behaviors of servant leaders and the work environments where they are effective. The research procedure consisted of a three-round Delphi to gain consensus on responses to four key research questions. From your experience and observation, what are the key words or phrases that describe (1) the characteristics that distinguish servant leaders, (2) the behaviors that distinguish servant leaders, (3) the work environments in which servant leaders are effective, and (4) the work environments in which servant leaders are ineffective? The following groups were represented on the panel of experts: (a) appointed and elected officials, (b) authors, (c) business leaders, (d) clergy, (e) educators, (f) leaders of associations, and (g) leaders of volunteer organizations. The first round Delphi instrument was open-ended. The second round gained opinion by adding a Likert scale to the results of the first round. The third round Delphi instrument was used to gather opinions from each panel member using a revised Likert scale instrument. In the third round each panelist received the statistical information calculated from the second round. The characteristics, behaviors, and effective work environments, as agreed upon consensually by the panel of experts in the third round, were reported. Twenty-eight panelists participated in each of the three rounds of the Delphi study. The characteristics, behaviors, and effective work environments of servant leaders, as determined by the panel of experts, are presented and discussed. A Servant Leadership Inventory was created from the data. The self-rating inventory is offered as an instrument to create discussion and increase awareness about leadership based on service to others. / Ed. D.

Student misconceptions in science are common and may be present even for students who are academically successful. Concept inventories, multiple-choice tests in which the distractors map onto common, previously identified misconceptions, are commonly used by researchers and educators to gauge the prevalence of student misconceptions in science. Distractor analysis of concept inventory responses could be used to create profiles of individual student misconceptions which could provide deeper insight into the phenomenon and provide useful information for instructional planning, but this is rarely done as the inventories are not designed to facilitate it. Researchers in educational measurement have suggested that diagnostic cognitive models (DCMs) could be used to diagnose misconceptions and to create such misconception profiles. DCMs are multidimensional, confirmatory latent class models which are designed to measure the mastery/presence of fine-grained skills/attributes. By replacing the skills/attributes in the model with common misconceptions, DCMs could be used to filter students into misconception profiles based on their responses to concept inventory-like questions. A few researchers have developed new DCMs that are specifically designed to do this and have retrofitted data from existing concept inventories to them. However, cognitive diagnostic assessments, which are likely to display better model fit with DCMs, have not been developed. This project developed a cognitive diagnostic assessment to measure knowledge and misconceptions about Newton's laws and fitted it with the deterministic input noisy-and-gate (DINA) model. Experienced physics instructors assessed content validity and Q-matrix alignment. A pilot test with 100 undergraduates was conducted to assess item quality within a classical test theory framework. The final version of the assessment was field tested with 349 undergraduates. Results showed that response data displayed acceptable fit to the DINA model at the item level, but more questionable fit at the overall model level; that responses to selected items were similar to those given to two items from the Force Concept Inventory; and that, although all students were likely to have misconceptions, those with lower knowledge scores were more likely to have misconceptions. / Doctor of Philosophy / Misconceptions about science are common even among well-educated adults. Misconceptions range from incorrect facts to personal explanations for natural phenomena that make intuitive sense but are incorrect. Frequently, they exist in people's minds alongside correct science knowledge. Because of this, misconceptions are often difficult to identify and to change. Students may be academically successful and still retain their misconceptions. Concept inventories, multiple-choice tests in which the incorrect answer choices appeal to students with common misconceptions, are frequently used by researchers and educators to gauge the prevalence of student misconceptions in science. Analysis of incorrect answer choices to concept inventory questions can be used to determine individual student's misconceptions, but it is rarely done because the inventories are not known to be valid measures for this purpose. One source of validity for tests is the statistical model that is used to calculate test scores. In valid tests, student's answers to the questions should follow similar patterns to those predicted by the model. For instance, students are likely to get questions about the same things either all correct or all incorrect. Researchers in educational measurement have proposed that certain types of innovative statistical models could be used to develop tests that identify student's misconceptions, but no one has done so. This project developed a test to measure knowledge and misconceptions about forces and assessed how well it predicted student's misconceptions compared to two statistical models. Results showed that the test predicted student's knowledge in good agreement and misconceptions in moderate agreement with the statistical models; that students tended to answer selected questions in the same way that they answered two similar questions from an existing test about forces; and that, although students with lower test scores were more likely to have misconceptions, students with high test scores also had misconceptions.

This work considers inventory systems with two demand classes, where advance demand information is available. Three related scenarios are presented: three-stage production-inventory systems are studied in first two, whereas pure inventory systems are studied in the last scenario. In the first scenario, continuous review production-inventory systems are considered, where only one class provides advance demand information and early demand fulfillment is permitted. A new approach for production replenishment and order fulfillment in such systems is proposed, which combines the benefits of early fulfillment with Kanban-based pull systems. Simulation is used to compare the performance of the resulting policy with two other policies for a variety of scenarios (depending on the arrival rates, system utilizations, cost structures, arrival ratio, priority levels and amount of the advance demand information). A simulation-based lower bound on the optimal cost is established for some specific scenarios. The proposed policy outperforms the existing policies in every setting considered. Also, the proposed policy has added advantage of both retaining the benefit at high system utilizations and increasing the benefit up to the maximum level of advance demand information provided. A small fraction of customers providing advance demand information with early fulfillment acceptable is shown to have higher benefit than all customers providing same advance demand information with no early fulfillment. In second scenario, both classes provide advance demand information in production-inventory systems, though only one class accepts early fulfillment. Different levels of system utilization, arrival ratio and backorder cost are considered in the simulation experiments to show the superiority of early fulfillment. Also, experiments suggest that lowering the expected supply lead time may be more beneficial than increasing the demand lead time by the same amount for production-inventory systems with utilization dependent supply lead times. In third scenario, pure inventory systems are considered, where the demand classes provide different amount of advance demand information, and only one class accepts early fulfillment. The structure of an optimal policy is analytically characterized for periodic review systems under some specific conditions. / Ph. D.

This research was undertaken to investigate the assessment of the spatial visualization skills of first-year engineering students. This research was conducted through three approaches: (1) a review of cogent research framed by a spatial visualization matrix, (2) the development and validation of an Engineering Graphics Concept Inventory, and (3) an investigation into the relationship into the correlations between 3D modeling skills and performance on the Purdue Spatial Visualization Test: Rotations (PSVT:R) and the Mental Cutting Test (MCT). The literature reviewed spans the field of published research from the early 1930's to the present. This review expands and provides a new direction on published research as it is viewed through the lenses of the four common pedagogical approaches to teaching spatial visualization: the standard approach, the remedial approach, computer-aided design, and the theory-informed approach. A spatial visualization matrix of criteria was developed to evaluate each of the methods. The four principle criteria included: learning outcomes, active and engaged learning, stage of knowledge, and explanatory power. Key findings from the literature review indicate the standard method is not the most effective method to teaching spatial visualization while the theory-informed method as evaluated by the matrix is the most effective pedagogical approach of the four methods evaluated. The next phase of this research focused on the two-year development, validation, and reliability of an Engineering Graphics Concept Inventory given to over 1300 participants from three universities. A Delphi method was used to determine the key concepts identified by the expert panel to be included in the inventory. A student panel of 20 participants participated in the pilot study of "think aloud" protocols to refine inventory test items and to generate the appropriate distractors. Multiple pilot studies coupled with a detailed psychometric analysis provided the feedback and direction needed for the adjustment of test items. The reported Cronbach's α for the final instrument is .73, which is within the acceptable range. The inventory is ready to be implemented and the predictability of the instrument, in reference to students' spatial visualization skills, to be researched. The final chapter of this research was a correlational study of the relationship between first-year engineering student's 3D modeling frameworks and their performance on the PSVT:R and the MCT. 3D modeling presence in graphical communications has steadily increased over the last 15 years; however there has been little research on the correlations between the standard visualization tests and 3D modeling. 220 first-year engineering students from Embry-Riddle Aeronautical University participated in the study in the fall of 2011. The main findings from this research indicate there is no significant correlational relationship between the PSVT:R and a student's 3D modeling ability, but there is one for the MCT. The significant correlational factors reported for the MCT and modeling aptitude for the three assignments are: r = .32 (p < 0.05), .36 (p< 0.01), and .47 (p< 0.01). These findings may be used by undergraduate educators and course administrators to more effectively organize engineering graphics education to yield students with deeper, more meaningful knowledge about engineering graphics and its inherent connection throughout the engineering curriculum. Together these three studies represent a sequential exploratory mixed methods approach that intertwines qualitative interviews and observations to frame the quantitative instrument and data collection. Results of this study can be used to guide the assessment of incoming freshmen engineering students, and the modification and development of engineering graphics courses. / Ph. D.

yes / Simulation is undoubtedly a very useful tool for modelling a system specifically in the presence of stochastic elements and complex interactions between the system entities. In this paper, a simulation model to support decision making in ship scheduling for Maritime Inventory Routing Problem (MIRP) with particular application to cement distribution is presented. The system under study is a combined discrete and continuous system, where a heterogeneous fleet of ships with various sizes and types of contracts transport bulk cement products from production facility (Central Supply, CS) of a cement company to its packing plants (Distribution Centres, DCs). The simulation model in this study has been designed and developed thoroughly to emulate the complexity of the real system of the MIRP. The simulation model has demonstrated the capability to provide support for decision making in ship scheduling of the heterogeneous shipping fleet in the following forms: (a) real time states of inventory levels at CS and DCs and (b) ships’ routing. In addition, one of the main strength of this simulation model is its flexibility. It can be easily expanded or adjusted to different size of system entities for example number of CSs, DCs, berths, vessels, and products. / Support for this research is provided by the Directorate of Higher Education, Ministry of National Education, Republic of Indonesia

Emerald ash borer (Agrilus planipennis Fairmaire) (EAB) is an invasive, wood-boring beetle (Coleoptera: Buprestidae) introduced unintentionally to the United States from East Asia that infests and eventually kills native ash trees (Fraxinus spp.). First detected near Detroit, Michigan in 2002, EAB had spread to fifteen U.S. states by 2011, killing an estimated 50 million ash trees along the way. EAB was first discovered in Virginia in 2003 and re-infested the state in 2008, raising concerns over impacts that the invasive pest might have on municipal urban forests and street trees. Despite these concerns, little is known about native ash abundance in Virginia's urban forests; as a result, potential EAB impacts have been difficult to project. In this study, street tree assessments were conducted in fourteen Virginia municipalities using i-Tree Streets®, which is a software program developed by the U.S. Forest Service that uses field inventory data to estimate street tree abundance and composition along with the quantity and monetary worth of functional benefits provided by these street trees. In addition to estimating potential losses of functional benefits provided by native ash street trees, information obtained from Virginia Dept. of Transportation was used to estimate the potential cost of removing these trees from the street side. The assessment indicated that there are about 4,600 native ash street trees in the fourteen studied localities and that native ash species comprise about 2% of municipal street tree populations on average. The highest relative abundance of native ash was found in Winchester City (5.8% of all street trees) whereas Richmond City had the greatest number of native ash street trees (estimated at 1,417). In terms of species importance (which accounts for both the relative abundance and relative size of trees in the population), only two localities (City of Roanoke and Town of Abingdon) had a native Fraxinus species among the top-five most important street tree species in the locality. In contrast, every municipality had at least one Acer species among the top-five, and eight of fourteen localities had at least one top-five Quercus species. Native ash street trees in the studied localities were estimated to provide functional benefits (energy conservation, stormwater mitigation, air pollution abatement, carbon sequestration, and aesthetic contributions) valued at over $535,000 annually, or roughly $38,000 per locality. In addition, carbon stored in these trees (about 17 million kilograms) was valued at nearly $277 thousand. The total estimated cost of removing lost ash trees was estimated at nearly $1.75 million, averaging about $124,000 for each municipality, and replacing the canopy cover and basal area provided by existing native ash street trees would exceed $17 million. In total, the studied localities would incur a gross financial impact of about $20.26 million due to losses of functional benefits and structural assets provided by native ash street trees. / Master of Science

A specialized lot size model for procurement of direct material items is applied in a specific manufacturing firm. Simulation studies are utilized for determining the effectiveness of the lot size model for use in a multiproduct MRP production system having a specific product structure. Measures of effectiveness with respect to cost categories including shortage frequency, material costs and holding costs will be obtained based on a range of demand patterns and levels. These studies focus on five end items representative of the population of brands manufactured at the company under consideration. The results of the study provide a methodological basis for system wide implementation of model based material ordering policy. / M.S.

Recursion is one of the most important and hardest topics in lower division computer science courses. As it is an advanced programming skill, the best way to learn it is through targeted practice exercises. But the best practice problems are hard to grade. As a consequence, students experience only a small number of problems. The dearth of feedback to students regarding whether they understand the material compounds the difficulty of teaching and learning CS2 topics. We present a new way for teaching such programming skills. Students view examples and visualizations, then practice a wide variety of automatically assessed, small-scale programming exercises that address the sub-skills required to learn recursion. The basic recursion tutorial (RecurTutor) teaches material typically encountered in CS2 courses. The advanced recursion in binary trees tutorial (BTRecurTutor) covers advanced recursion techniques most often encountered post CS2. It provides detailed feedback on the students' programming exercise answers by performing semantic code analysis on the student's code. Experiments showed that RecurTutor supports recursion learning for CS2 level students. Students who used RecurTutor had statistically significant better grades on recursion exam questions than did students who used a typical instruction. Students who experienced RecurTutor spent statistically significant more time on solving programming exercises than students who experienced typical instruction, and came out with a statistically significant higher confidence level. As a part of our effort in enhancing recursion learning, we have analyzed about 8000 CS2 exam responses on basic recursion questions. From those we discovered a collection of frequently repeated misconceptions, which allowed us to create a draft concept inventory that can be used to measure student's learning of basic recursion skills. We analyzed about 600 binary tree recursion programming exercises from CS3 exam responses. From these we found frequently recurring misconceptions. The main goal of this work is to enhance the learning of recursion. On one side, the recursion tutorials aim to enhance student learning of this topic through addressing the main misconceptions and allow students to do enough practice. On the other side, the recursion concept inventory assesses independently student learning of recursion regardless of the instructional methods. / Ph. D.

Nontimber forest products (NTFPs) play an important role in the lives of people who rely on forests. An absence of data on the size of harvests, their location, and the economic value of NTFPs prevents effective management and full utilization by all stakeholder groups. We set out to measure one important NTFP sector -- the medicinal plant trade in the diverse deciduous forests of the eastern United States, by surveying licensed buyers of ginseng (Panax quinquefolius) in 15 states about purchasing of other untracked species. To combat potential coverage and non-response bias we created a place-based model that predicted the probability of purchasing non-ginseng medicinals based on buyer location and used this to build more robust estimates. This viable method for estimating NTFP output is a replicable system that can be applied in other regions and for other products. We reviewed the literature and hypothesized biophysical and socioeconomic factors that might contribute to the prevalence of non-ginseng purchasing, and tested them on the respondents using multinomial logistic regression. The significant variables were used in two-step cluster analysis to categorize respondents and non-respondents in high or low production areas. Volume was assigned to non-respondents based on respondent behavior within each cluster. Both were then summed to estimate total output. The results depict trade volume and prices paid to harvesters for 11 medicinal NTFP species. There was significant variation between products. Two species, black cohosh (Actaea racemosa) and goldenseal (Hydrastis canadensis), accounted for 72 percent of trade volume and 77 percent of the value paid to harvesters. The total first-order value for all species estimated was 4.3 million $USD. The discrepancy between point-of-sale and retail value implies room for increasing value for all stakeholders at the base of the supply chain. Harvests for most species were concentrated in the central Appalachian coalfields. We also sought to understand what motivated or deterred participation by conducting qualitative interviews with buyers and other stakeholders. Buyers were interested in knowing the size and value of the trade, but had concerns about losing access to the resource, which was rooted in past experience with land managers and policy-makers, and conflicting discourse between stakeholders about the state of the trade and of wild populations. Many institutional deliverables are not well matched with the realities or priorities of the traditional trade. We describe potential avenues for collaboration and reciprocity, including providing market research and certifying or providing technical support for sustainably wild harvested material in addition to ongoing support for cultivation. / PHD / Nontimber forest products (NTFPs) are sources of sustenance and livelihood for people around the world. This broad category includes parts of plants such as barks, roots, and fruits, and fungi harvested for food, medicine, decoration, for use in crafts and cultural and spiritual ceremonies. They are harvested for personal use, and sold into local and global supply chains. Commercially harvested NTFPs have a dual nature. They have the potential for providing income without having the kind of large-scale disturbance caused by logging or other more impactful extractive industry. At the same time, most forests are not managed for NTFP production, and the ecological impacts of most NTFP activity are difficult to assess. Habitat loss and harvesting pressure has led to the monitoring and regulation in the trade of one iconic medicinal NTFP American ginseng (Panax quinquefolius) For the majority of NTFPs, the scale, value and distribution of the trade is unknown, presenting a barrier to effective management and institutional investment in the trade. We sought to better understand one important NTFP supply chain, the trade in medicinal plants occurring in eastern deciduous forests using a voluntary survey program. To accomplish this, we surveyed and interviewed registered ginseng buyers in 15 states about the other products they purchase. This dissertation is divided into three parts with three different objectives. The first is to describe the trade in medicinal NTFPs from eastern forests. This includes what species are being harvested, how harvests are distributed throughout the study area, the value of surveyed species to producers, and market structure close to the point of sale. We found that the majority of the trade was taking place in central Appalachia. The majority of the trade in terms of value and total output was concentrated in two species, goldenseal (Hydrastis canadensis) and black cohosh (Actaea racemosa). The second chapter seeks to create a replicable method for projecting total volume for the most commonly harvested species, including predicting the buying of the majority of respondents who did not participated. We created a model that predicted the likelihood of a respondent purchasing non-ginseng based on characteristics of their location associated with the trade. The third chapter uses interviews with buyers and other participants to explore how to improve participation in NTFP studies and make the results more useful for stakeholders.