The Greenbelt Corridor (GBC), located in a floodplain of the Elm Fork of the Trinity River, contains patches of bottomland forest and serves as part of Lake Lewisville’s flood control backwaters. This study examines forest structure and composition in relation to topographic position and forest stage in the GBC. Thirty two plots were surveyed within various stage classes, topographic positions, and USDA soil types. Trees were identified and measured for height and DBH. Density, basal area, and importance value for each of species was calculated. Soil and vegetation were analyzed using ANOVA, Principal Component Analysis, Canonical Correlation, Canonical Correspondence Analysis and Cluster Analysis. Tests confirmed that calcium carbonate and pH show significant differences with topographic positions but not with forest stage. Potassium shows no significant difference with soil texture class. Sand shows a strong negative correlation with moisture, organic matter, organic carbon and negative correlation with calcium carbonate and potassium. Silt shows positive correlation with moisture, organic matter, organic carbon, and calcium carbonate. Clay shows strong positive correlation with moisture, organic matter and organic carbon but negative correlations with pH. Swamp privet is dominant tree types in wetland forest. Sugarberry cedar elm, green ash and American elm are widely distributed species in the study area covering low ridges, flats, and slough. In total, density is significantly different in wetland low forest and late successional stage and basal area is significantly different in early successional stage and late successional stage. Other results show that clay is negatively correlated with American elm but positively correlated with cedar elm. Organic matter and moisture shows a strong positive correlation with cedar elm. Calcium carbonate is associated with green ash and swamp privet, sand is associated with sugarberry and red mulberry, silt and pH with cedar elm and bur oak.

A deorbiting drag device is being designed and built by the University of Toronto Institute for Aerospace Studies/Space Flight Laboratory (UTIAS/SFL) to be demonstrated on the Canadian Advanced Nanospace eXperiment 7 (CanX-7) satellite. CanX-7 will address the growing issue of space debris by designing a drag sail device that will be demonstrated for cubesat-sized satellites. Mission analysis done to ensure the drag device functions properly and deorbits within the required lifetime is performed while varying different properties such as drag coefficient, effective drag area, and solar cycle variations. The design evolution of the device is documented and the chosen design, along with several stages of prototyping, is described. The individual components that make up the device are described as are preliminary numerical analyzes. Finally, the test plan required for the device is described with several deployment experiments and risk reduction tests documented.

A deorbiting drag device is being designed and built by the University of Toronto Institute for Aerospace Studies/Space Flight Laboratory (UTIAS/SFL) to be demonstrated on the Canadian Advanced Nanospace eXperiment 7 (CanX-7) satellite. CanX-7 will address the growing issue of space debris by designing a drag sail device that will be demonstrated for cubesat-sized satellites. Mission analysis done to ensure the drag device functions properly and deorbits within the required lifetime is performed while varying different properties such as drag coefficient, effective drag area, and solar cycle variations. The design evolution of the device is documented and the chosen design, along with several stages of prototyping, is described. The individual components that make up the device are described as are preliminary numerical analyzes. Finally, the test plan required for the device is described with several deployment experiments and risk reduction tests documented.

No description available.

The renewed academic interest in using solar sails as a source of spacecraft propulsion has been accompanied by a recent fervor of investigations into non-ideal and off-nominal sail performance considerations. One of the most influential considerations, uncertain optical degradation, has been shown to present significant trajectory design difficulties. This paper investigates the potential of using a mid-course degradation model update to mitigate the risk of missing the target destination in a sample 300 day Earth-Venus trajectory. Using a range of potential degradation profiles, it is shown that correcting in the first half of the mission is highly likely to result in a trajectory that arrives sufficiently close to Venus at the end of the mission timeframe. Depending on the exact extent of the uncertainty, the data suggests that the latest a correction should take place ranges from 150 to 240 days into the mission. The influence of two different parameters, the extent and rate of degradation, are compared to show that the former of the two is more impactful on correcting timing than the latter.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17984号 / 工博第3813号 / 新制||工||1584(附属図書館) / 80828 / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 山川 宏, 教授 松尾 哲司, 准教授 中村 武恒 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The ISAS/JAXA Solar Power Sail mission, bound to explore the Jupiter trojans, will face many challenges during its journey. The landing manoeuvre is one of the most critical parts of any space mission that plans to investigate the surface of celestial bodies. Asteroids are mostly unknown bodies and in order to plan a successful landing on their surface, a great number of landing scenarios need to be taken into account. For the future mission to the Jupiter trojans, a study of the landing dynamics and their effects on the lander has to be done. A simple model of a lander has been created based on a design for the ISAS/JAXA Solar Power Sail mission, and the possible landing scenarios have been simulated. For this case, only the last part of the landing, which will be a free-fall has been taken into account. The lander is modelled as a rigid structure with a landing gear composed of four legs. The surface has been modelled as a flat plane with different inclinations and the possibility of including small obstacles or terrain roughness has been implemented. In the model, the lander is allowed 6 degrees of freedom. Several landing possibilities are tested with residual velocities and deviations in the starting point, and the stability of the lander is evaluated respect its geometry. Damping strategies have been considered to protect the instruments and reduce the impact, allowing for a safer landing. The effect of including crushable honeycomb dampers in the legs is also implemented, simulated and evaluated, by using a model of crushable honeycombs with different characteristics. In addition, the model includes also the position, direction and characteristics of the thrusters. Thus, it could be used to study other phases of the landing sequence where active control of the lander is needed, and evaluate the behaviour and response of different control-loop algorithms for attitude and position control of the lander.

Aims: The initial aim of this thesis was to understand the relationship between non-psychotropic medication and risk of suicidality. This was achieved by conducting a systematic review, which, among other conclusions, identified the need for improved estimation of risk of suicide and attempted suicide associated with antiepileptic drugs (AEDs). This stimulated this programme of research which sought to estimate the risk of suicide and other causes of unnatural death in people with epilepsy, the role of AEDs in fatal poisonings, the risk of self-harm in people with epilepsy and factors associated with self-harm amongst those people with epilepsy. Methods: Cohorts of individuals with prevalent epilepsy were identified separately in two population-based linked-primary care datasets: the Clinical Practice Research Datalink (CPRD) in England and the Secure Anonymised Information Linkage (SAIL) in Wales. Individuals were matched on age, gender and general practice to up to 20 people without epilepsy. The risks of cause-specific types of unnatural death (e.g. suicide, accident) were estimated using stratified Cox proportional hazards models, adjusted for level of deprivation. From each of the prevalent epilepsy cohorts, individuals with incident epilepsy, no history of self-harm and who were new users of the AEDs; carbamazepine, lamotrigine or valproate, were identified. The risk of first self-harm event associated with each AED compared to valproate was estimated using Inverse Probability of Treatment Weighting propensity score analysis. Estimates from each dataset were combined in a random effects meta-analysis. In the CPRD, the risk of self-harm in the incident epilepsy cohort versus a comparison cohort was estimated using a stratified Cox proportional hazards model. From this cohort, a nested case-control study was constructed. Individuals with a first self-harm event (cases) were matched to up to 20 people with no history of self-harm (controls). Conditional logistic regression was used to estimate the risk of self-harm associated with various factors including history of mental illness diagnoses, referrals and AED utilisation. Results: There were 44,678 and 14,051 people in the prevalent epilepsy cohorts and 891,429 and 279,365 in the comparison cohorts, in the CPRD and the SAIL respectively. Increased risks of suicide (HR 2.15, 95%CI 1.51-3.08) and accidental death (HR 2.97, 95%CI 2.54-3.48) were observed for people with epilepsy versus the comparison cohort, from the deprivation-adjusted meta-analysed estimates. Overall, AEDs were involved in 9.7% (95%CI 3.6%-19.9%) of the 62 poisoning deaths in people with epilepsy. There were 5,107 new users of carbamazepine, lamotrigine or valproate with incident epilepsy in the CPRD and 2,654 in the SAIL. No increased risk of self-harm was evident for carbamazepine (HR 1.53, 95%CI 0.89-2.64) or lamotrigine (HR 1.35, 95%CI 0.79-2.29), compared to valproate, from the meta-analysed estimates. In the CPRD, there were 11,690 individuals with incident epilepsy and 215,569 in the comparison cohort. The deprivation-adjusted hazard ratios for first self-harm event were 5.31 (95%CI 4.08-6.89) in the year following diagnosis and 3.31 (95%CI 2.85-3.84) in subsequent years. The nested-case control study derived from this incident epilepsy cohort included 273 cases of first self-harm and 3,790 controls. An increased risk of self-harm was associated with history of a mental illness diagnosis (OR 4.08, 95% CI 3.06-5.42) or referral to specialist psychiatric services (OR 3.41, 95% CI 2.63-4.43), compared to none; or being prescribed no AEDs (OR 1.47, 95% CI 1.01-2.12) or two AEDs (OR 1.84, 95% CI 1.33-2.55) in the 90 days prior to index date, compared to a single AED. Augmentation of AED treatment carried an elevated risk (OR 2.12, 95% CI 1.38-3.26) whereas there was no evidence to indicate that switching from one AED to another altered risk (OR 0.69, 95% CI 0.21-2.23). Conclusions: Compared to those without the condition, people with epilepsy are at an elevated risk of unnatural death, including suicide and accidental death, and nonfatal self-harm. The risk of self-harm is particularly elevated in the year following diagnosis of epilepsy but persists beyond this. Factors associated with increased risk of self-harm within the epilepsy population include prior mental illness and referral to psychiatric services. There was no evidence of difference in the risk of self-harm associated with carbamazepine or lamotrigine compared to valproate, but further replication of this result would be beneficial. However, treatment with multiple AEDs and augmentation of AED treatment increase the risk of self-harm within this population. These may be markers of uncontrolled epilepsy.

This study of Western Empire is split into two distinct parts: (1) historical research of the life of the vessel, relying on primary documents; and (2) analysis of the deep water survey data. The first part concentrates on the historical documents that constitute the history of Western Empire. The second part begins with a review of the tools and procedures used in performing the deep water survey. An analysis of the information that can be taken from such a study will follow, and it concludes with suggestions for remotely operated vehicle operators when performing an on-the-fly survey of shipwrecks in deep water. The official ship logs, crew agreements, and contemporary newspaper articles are used to recreate the life of Western Empire and shed light on a period in which wooden sailing ships were being displaced by iron ships and steam power.

Contributions to two missions are presented. The first is a demonstration mission called CanX-7 that uses a 4 square metre drag sail to de-orbit a 3.5 kg satellite. In order to estimate the effectiveness of the drag sail, a novel method is developed that takes into account the time-varying nature of the projected drag area. The Space Flight Laboratory designed drag sail is shown to be sufficient to de-orbit the CanX-7 spacecraft within the 25 year requirement. The Antarctic Broadband demonstrator spacecraft is a 20 cm cubical nanosatellite that will demonstrate the feasibility of a Ka-band link between the research community in Antarctica and stakeholders in Australia. In support of this mission, a passive thermal control subsystem is designed that will keep all the components within their operational temperature limits at all times throughout the mission.