With the growing threat of orbital debris impacts to space structures, the development of space shielding concepts has been a critical research topic. In this study, numerical simulations of the hypervelocity impact response of stacked aluminum 6061-T6 sheets were performed to assess the effects of layering on penetration resistance. This work was initially motivated by set of experimental tests where a stack of four aluminum sheets of equal thickness was observed to have a higher hypervelocity ballistic resistance than a monolithic aluminum sheet with the same total thickness. A set of smoothed particle hydrodynamic simulations predicted a 40% increase in the ballistic limit for a 6-layer target compared to a monolithic sheet. In addition, the effect of variable sheet thickness and sheet ordering on the impact resistance was investigated, while still maintaining a constant overall thickness. A set of thin layers in front of a thick layer generally lead to a higher predicted ballistic limit than the inverse configuration. This work demonstrates an increase in the performance of advanced space shielding structures associated with multi-layering. This suggests that it may be possible to dramatically improve the performance of such structures by tailoring the material properties, interfaces, and layering concepts.

This thesis aimed to improve decision-maker access to economic information by testing a pricejusting methodology to annually update expenditure information for economic impacts analyses and by conducting a trends analysis of economic sector contributions to a regional economy. A secondary data analysis of historical angler survey data generated expenditure profiles adjusted over time using price indices. A replication survey was conducted to compare expenditures. Grouping anglers by trip type (one-day/multiple-day) resulted in expenditure profiles that were generally consistent over time as anglers spent approximately $75 and $130 on one-day and multiple-day trips, respectively. These expenditures resulted in total economic impacts of over $13 million. A series of automatic social accounting matrices (ASAM) were then employed to execute economic base analyses, quantifying the role of sectors in the regional economy. The tourism sector consistently contributed over 20% of gross employment and almost 10% of gross output over time.

The existing research in the field of tourism has exhibited a clearer understanding of how residents perceive the dynamic and complex phenomena of tourism. Since the goals of tourism planning and development are to seek maximization of benefits and minimization of the costs of tourism, it is apparent that the effective evaluation of tourism impacts will be valuable information in successful strategies for tourism product development and operation. With these perspectives, this study attempted to investigate the underlying dimensions explaining residents' perceived tourism impacts and to identify relationships between determinants and residents' perceived tourism impacts. The social exchange theory provided a fundamental framework for this study. The dimensions of the tourism impacts were addressed by explicating economic, social/cultural, environmental/physical impacts of tourism development from literature review. Ten determinants which affect residents' perception were identified from past research on tourism impacts: birthplace, length of residency, community attachment, tourism related jobs, recreational activity, tourist contacts, tourism policy participation, travel experience, levels of tourism development, and growth of community. Norfolk/Virginia Beach/Newport News MSAs areas were selected as the study area because these areas provide fine multifaceted tourism attractions, generates many tourists, and influences the host community' life. A total of 316 useful respondents (13.2%) were analyzed by using the SPSS program. Two research questions were proposed. Factor analysis, multiple regression analysis, and multivariate analysis of variance (MANAOVA) were performed. From the findings of this study, residents perceived the impacts of tourism as five different dimensions embodying economic benefits, social costs, cultural enrichment, environmental deterioration, and physical enhancement. Their perceptions were affected by eight out of ten determinants. Generally, a higher level of tourism development and growth of community affects residents' perceptions of tourism impacts. Residents who were natives, who have higher community attachment, and who had been living in the research area for a shorter time period had more concerns about the perceived impacts of tourism. In addition, perceived tourism impacts were significantly differed across household incomes and ethnic groups. For future study, it is suggested that a further investigation of determinants affecting residents' perceptions is needed for better understanding and explanation of the impacts of tourism. It is believed that this study would help tourism planners and developers formulate and implement better strategies. / Master of Science

No / This paper engages with policy on meeting development goals for water through interventions, which promote good governance. Addressing an under-researched area, we propose a new analytical framework for understanding water governance, not as a set of abstract principles, but as interlinked processes with variable practical outcomes for poor people. The framework is informed by theories of governance, institutions and structuration, empirical research and field insights. We apply the framework to a case in south-western Tanzania, and we identify a range of issues for further research, particularly relating to water access for the poor.

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The Hybrid III and NOCSAE headforms are two headforms used in impact testing, though their vibrational characteristics are not well understood. They may have different kinematic responses in various impact scenarios if the impact excites any of their natural frequencies; resonance is especially likely to occur in short-duration impacts with a wider frequency spectrum. The same impact on two headforms that perform similarly in blunt impacts can be much different in shorter-duration projectile impacts due to the vibrational responses. The research presented in this thesis had three objectives: to identify the natural frequencies of the Hybrid III and NOCSAE headforms and compare them with published human head values to determine which has a more biofidelic vibrational response; to quantify the frequency response of different baseball catcher's masks and assess their abilities to limit vibrations transferred to the headforms; and to compare kinematic and frequency responses between headforms in different impact scenarios (high-speed, low-mass projectile impacts vs. low-speed, high-mass pendulum impacts) and see how they are affected by various types of head protection. The results show the importance of considering frequency content in impact testing, suggesting that the NOCSAE headform may be more biofidelic in short-duration impacts since its natural frequencies better align with those seen in the human head. The catcher's masks experienced greater vibrational responses than the headforms, but since the NOCSAE's first natural frequency falls within the bandwidth being excited, resonance was seen in this headform's acceleration responses for the projectile baseball impacts. Lastly, while both headforms had higher peak linear accelerations (PLAs) from the short-duration projectile impacts than the pendulum impacts, the projectile impacts caused high frequencies to be excited in the NOCSAE headform, while only exciting low frequencies in the Hybrid III. These results may not be as relevant for long-duration loadings, as indicated by the similar responses between headforms for both the pendulum and helmeted projectile impacts. However, when a wide range of frequencies are being excited with short-duration impacts, these results are important to consider, since natural frequency excitation can influence head injury risk due to higher accelerations. / Master of Science / The Hybrid III and NOCSAE headforms are dummy headforms used in impact testing, but their vibrational characteristics are poorly understood. They may perform differently in certain loading environments due to structural differences; their frequency responses might differ based on impact characteristics. Short-duration impacts excite a wider range of frequencies than longer-duration (padded) impacts. While headforms generally perform similarly during padded impacts where resonant frequencies are avoided, excitation of these frequencies during short-duration impacts can result in different kinematic measurements between headforms. The research presented in this thesis had three objectives: to identify the natural frequencies of the Hybrid III and NOCSAE headforms and compare them with published human values to determine which better represents the head's vibrational response; to quantify the vibrational characteristics of different baseball catcher's masks and assess their abilities to limit vibrations transferred to the headforms; and to compare kinematic and frequency responses between headforms in different impact scenarios (high-speed, low-mass projectile impacts vs. low-speed, high-mass pendulum impacts) and see how they are affected by various helmets. The results show the importance of considering frequency content in impact testing, suggesting that the NOCSAE headform behaves more like the human head in short-duration impacts. Even though the catcher's masks "rang" more than the headforms, the vibrations from the projectile impact were in the appropriate range to excite the NOCSAE's natural frequencies. Thus, there was still an oscillatory response in this headform even when protected with the mask. Lastly, the projectile impacts caused higher accelerations in both headforms than the pendulum impacts. However, high frequencies were only experienced by the NOCSAE headform due to the projectile impacts; for the same impact, the Hybrid III just had low frequencies excited. These results are not as relevant for long-duration impacts, since there were similar responses in both headforms for both the pendulum and helmeted projectile impacts. However, they are very applicable for the short-duration impacts that excite a wide range of frequencies, since natural frequency excitation can increase the risk of head injury due to higher acceleration magnitudes.

The goals of this study were to measure the ability of catcher's masks to attenuate head accelerations upon impact with a baseball, and to compare these head accelerations to established injury thresholds for concussions. Testing involved using a pneumatic cannon to shoot baseballs at an instrumented (3-2-2-2 accelerometer array) Hybrid III headform (a 50th percentile male head and neck) with and without a catcher's mask on the head. The ball speed was controlled from approximately 26.8 – 35.8 m/s (60 – 80 mph) and regulation NCAA baseballs were used. Peak linear resultant acceleration was 140 – 180 g without a mask and 16 – 30 g with a mask over the range of balls speeds investigated. Peak angular resultant acceleration was 19500 – 25700 rad/sec2 without a mask and 2250 – 3230 rad/sec2 with a mask. The Head Injury Criterion was 93 – 181 without a mask and 3 – 13 with a mask and the Severity index was 110 – 210 without a mask and 3 – 15 with a mask. Catcher's masks reduced head acceleration metrics by approximately 85% when baseballs were impacted with just the headform. Head accelerations with a catcher's mask were substantially lower than contemporary injury thresholds, yet evidence indicates that baseball impacts to the mask still result in concussions. / Master of Science

This thesis contains two studies that explore different methods of visitor management in recreation. The management strategies studied here are both relatively indirect approaches intended to minimize the environmental and social impacts that visitors cause in protected areas. The Annapolis Rocks study focuses on visitors' evaluations of a site management strategy that shifted camping from a flat, open area to constructed side-hill campsites. A visitor questionnaire was administered before and after the treatment to determine visitors' ratings of importance and satisfaction for various campsite attributes. We found some evidence of visitor displacement but concluded that the site management strategy supported the intentions of the managers. The Leave No Trace study evaluates the effectiveness of the Trainer courses in improving the knowledge, ethics, and behavior of the participants and encouraging them to teach others in the community. This study employed pre-course, post-course, and follow-up questionnaires to evaluate the participants' short-term and long-term gains from the course. Trainer course participants showed significant short-term and long-term gains from the course, with a slight decline in the total gain four months after the course. The participants showed improvements in low-impact behaviors, suggesting that education is an effective visitor management strategy. These studies demonstrate that managers can be successful at controlling visitor impacts without relying on stringent regulations and enforcement. / Master of Science

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