Paradigms for service robotics

Suthakorn, Jackrit The Johns Hopkins University 2003 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Most of the robots produced to date have been <italic>industrial</italic> robots. These robots have taken the place of human laborers in hazardous, boring, or otherwise dangerous manufacturing tasks. The number of robots being used in industrial production has grown significantly. In contrast, the use of personal robots, often called service robots, is still limited. Service robots perform tasks for people rather than serving an industrial manufacturer. Of late, the idea of service robotics has become a more interesting topic for both robotics researchers and the general public. The objective of this dissertation is to explore various concepts and applications in service robotics. This research is separated into three parts. <italic>Binary robotic manipulators</italic>. Continuous actuators, such as motors, actuate most robotic manipulators. These actuators require complex and expensive control and sensor systems. In this study, Discretely Actuated Hyper-Redundant (DAHR) manipulators are shown to be viable candidates for use in many applications. This study consists of describing the DAHR concept, formulating and numerically implementing a new inverse kinematics algorithm for this type of robotic manipulator using only the “mean” of the workspace density function; constructing a prototype, and performing experiments with the prototype. <italic>Robotic library systems</italic>. The robotic library system described here is a part of a unique robotics project called “Comprehensive Access to Printed Materials” (CAPM) at the Johns Hopkins University. The goal of the CAPM project is to design and build a prototype robotic library system for an off-site shelving facility of the JHU. The design, descriptions, and experimental results of a prototype mobile manipulator are reported. <italic>Self-replicating robots</italic>. The concept of a self-replicating machine was introduced more than fifty years ago by John yon Neumann. However, prior to the work performed in this dissertation, a fully autonomous self-replicating mechanical system, such as a self-replicating robot, had yet to be implemented. In this study, a set of underlying principles of self-replicating robotic systems is introduced. A series of prototype designs and their experimental results is described in stages beginning with a remote-controlled replicating robotic system, a semi-autonomous replicating robotic system, and finally a fully autonomous self-replicating system.

Singular behavior of minimal surfaces and mean curvature flow

Kleene, Stephen James The Johns Hopkins University 2010 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

This document records three distinct theorems that the author proved, along with his collaborators, while a graduate student at The Johns Hopkins University. The author, with M. Calle and J. Kramer, generalized a sharp estimate of Tobias Colding and William Minicozzi for the extinction time of convex hyper-surfaces in euclidean space moving by their mean curvature vector to a much broader class of evolutions studied by Ben Andrews in (1). Also, the author gave an alternate proof, first given by D. Hoffman and B. White in (17), of very poor limiting behavior for sequences of minimal surfaces in euclidean three space. Finally, the author, together with N. Moller in (23) constructed a new family of asymptotically conical ends that satisfy the mean curvature self shrinking equation in euclidean three space in all dimensions.

Flow problems in hyperbolic space

Xiao, Ling The Johns Hopkins University 2013 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The aim of this dissertation is threefold and it records three distinct results that the author along with her collaborators proved, during her time as a graduate student at The Johns Hopkins University. Firstly, with L. Lin, in [33] we defined a new modified mean curvature flow (MMCF) in hyperbolic space Hn+1 . We showed the existence, uniqueness and convergence of the MMCF of complete embedded star-shaped hypersurfaces with prescribed asymptotic boundary at infinity. The proofs of our main theorems closely follow the work of Guan and Spruck [16], and may be thought of as a parabolic analogue. Secondly, in [37] the author investigated the existence, convergence and uniqueness of the modified curvature flow of convex hypersurfaces (MCFC) in hyperbolic space with a prescribed asymptotic boundary. Finally, the author extended her result in [37] to the case of finding the general curvature flow of complete hypersurfaces (MGCF) in hyperbolic space with a prescribed asymptotic boundary at infinity. This is part of the project of generalizing Guan and Spruck's result in [20].

Data management in environmental monitoring sensor networks

Gupchup, Jayant The Johns Hopkins University 2012 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Data gathered from multi-month to multi-year battery-powered environmental monitoring sensor networks present numerous challenges. This thesis explores three problems. First, design issues related to loading, storing and data integrity are studied in detail. An end-to-end system addressing these tasks by decoupling deployment-specific and deployment-independent phases is presented. This solution places a strong emphasis on the ability to trace the origins of every collected measurement for provenance and scientific reproducibility. Second, we explore the problem of assigning accurate global timestamps to the measurements collected using the motes' local clocks. In deployments lacking a persistent gateway, a data-driven approach is employed to assign timestamps to within 10 parts per million. Building on these experiences, we developed a novel low-power approach to accurately timestamp measurements in the presence of random, frequent mote reboots. The system is tested in simulation and on a real deployment in a Brazilian rain forest. It is able to achieve an accuracy in the order of seconds for more than 99% of measurements even when a global clock source is missing for days to months. Lastly, this thesis explores a generic data-driven approach to reduce communication costs in order to increase network lifetime. In particular, spatial correlation among sampling stations is leveraged to adaptively retrieve data from a small subset of informative sensors rather than all instrumented locations. Soil temperature data collected every half hour for four months from 50 locations is used to evaluate this system. The method achieves a factor of two reduction in collected data with a median error of 0.06°C and 95th percentile error of 0.325°C. This work is part of the Life Under Your Feet project developed at the Hopkins Inter-Networking Research (HiNRG) and eScience Labs at the Johns Hopkins University. At the time of writing, the data collected for this project is available at http://www.lifeunderyourfeet.org.

The exotic rhythms of Don Ellis

Fenlon, Sean Patrick Peabody Institute of the Johns Hopkins University 2002 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

This dissertation examines the rhythmic innovations of jazz musician and composer Don Ellis (1934–1978), both in Ellis's theory and in his musical practice. It begins with a brief biographical overview of Ellis and his musical development. It then explores the historical development of jazz rhythms and meters, with special attention to Dave Brubeck and Stan Kenton, Ellis's predecessors in the use of “exotic” rhythms. Three documents that Ellis wrote about his rhythmic theories are analyzed: “An Introduction to Indian Music for the Jazz Musician” (1965), <italic> The New Rhythm Book</italic> (1972), and <italic>Rhythm</italic> (c. 1973). Based on these sources a general framework is proposed that encompasses Ellis's important concepts and innovations in rhythms. This framework is applied in a narrative analysis of “Strawberry Soup” (1971), one of Don Ellis's most rhythmically-complex and also most-popular compositions.

Chromosomal and carcinogenic effects of sequential HZE and low-LET irradiations

Simonson, Dustin Mark The Johns Hopkins University 2002 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

All persons are exposed to a natural background of ionizing radiations with different spatial patterns of energy deposition resulting in differential biologic response. Astronauts, aircrew and radioactive contamination clean-up personnel are exposed to particularly complex radiation spectra. The current method for calculating radiation-induced exposure limits in mixed radiation environments is based on the linear summation of non-threshold risks, a methodology grounded in the premise that each component of the radiation field acts independently of the presence of other components. The assumption of effect independence of in-vitro exposed samples was tested by evaluating the frequency of chromosome aberrations induced by sequential irradiation of immortalized human mammary epithelial cells with 1 GeV/nucleon <super> 56</super>Fe ions and <super>137</super>Cs gamma-rays. Experimental response was found to be significantly less than calculated on the basis of effect independence, but only when <super>56</super>Fe ions preceded the photon exposure. That there was order dependence is interpreted as evidence that response may not simply be a result of interactions between similar sublesions but rather may involve qualitatively different time-ordered parameters. The presence of this sub-additive response is phenomenologically similar to adaptive response, which had not been previously reported as a consequence to high-energy heavy ion irradiation. Calculations based on effect independence predict a significantly greater average number and lifetime cumulative incidence of breast cancers in female Sprague-Dawley rats irradiated with both <super>56</super>Fe ions and 250 MeV protons than was experimentally observed. This finding supports the hypothesis that the presence of non-additive response is not exclusively an <italic> in vitro</italic> phenomenon. Results from an evaluation of mammary epithelial cell response induced in a rat cancer model are marginally consistent with the use of <italic>in vivo</italic> induced chromosome aberrations as a biomarker of breast cancer risk. There is also an apparent association between the two endpoints relating to dependence on radiation quality. In conclusion, these data demonstrate that sequential exposures to both HZE and low-LET radiation may result in chromosomal and carcinogenic response that is inconsistent with effect independence. These results provide evidence that the linear summation of health risks from mixed HZE and low-LET radiation fields may not accurately reflect true risk.

The Armagnac faction: New patterns of political violence in late medieval France (Bernard VII, Count of Armagnac)

Pollack-Lagushenko, Timur R The Johns Hopkins University 2004 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

This dissertation examines the formation of political factions in France during the reign of Charles VI. I examine these political divisions, and the resulting violent struggles, not as aberrations but as parts of the emerging system of late medieval and early modern politics. My research shows that through factionalization different social groups were able to integrate local conflicts into a single system of national contestation, and that this praxis preserved a traditional set of hierarchical relationships during a period of massive economic dislocation. In order to analyze this new pattern of politics and violence, I focus on the clientele and alliances of Bernard VII, count of Armagnac, and demonstrate how elites from the traditionally autonomous and politically fragmented regions of Languedoc and Gascony became embroiled in the War of the Armagnacs and Burgundians. My study treats factionalization as a "total" social phenomenon: I examine the evolution of Armagnac seigneurial and comital powers, the interaction between the "national" civil war and the pre-existing tensions and disputes within southern France, the Armagnacs' organization and use of violence, and the interpenetration of faction and the royal government. The construction of new political networks that connected the intrigues within the royal council to struggles in distant and hereto isolated communities was part of an effort to control the crown's capacity for legitimation and the transfer of income in the form of taxes and wages. Many relationships that constituted the faction were not initiated by the count, but by relatively humble groups, such as peasants and artisans, as well as local elites, such as members of the middle nobility and urban consulates, who used bonds with social superiors to organize violence against local opponents and to secure military, financial and legal support from distant adherents of the same faction. Cooperation within factions was based not on traditional feudal bonds, but on new forms of voluntary association and service. In some key cases, mutual support was secured by strategic marriages and formal alliances, but more typically adherence to a faction involved simply the adoption of "nationally" recognized symbols and party labels.

Negotiating lordship: Efforts of the Consulat of Toulouse to retain autonomy under Capetian rule (ca. 1229--1315) (France)

Gardner, Christopher Kenrick The Johns Hopkins University 2002 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The dissertation explores the resistance and negotiations enjoined by the members of the town council of Toulouse (the Consulat) with the Capetian royal family, who came into possession of the town via the Treaty of Paris of 1229. My study investigates the ways the inhabitants sought to retain their juridical and jurisdictional autonomy as the Capetians sought to impose their oversight of the courts and administration of the town. Emphasis is placed on the agency of the Consules and their supporters to redefine their legal and cultural identities in a context of legal and administrative intrusion. The practical machinations of governance in an era of institutional experimentation (not “state-building,” as is often presumed) are also explored. The leading families of Toulouse who participated on the Consulat successfully resisted many of the demands placed upon them by the Capetian prince, Count Alfonse (1249–1271), and his successor, King Philip III (r.1271–1285), via a process I term “loyal resistance,” namely, avowals of loyalty from the Consules and <italic>universitas</italic> of Toulouse coupled with sweeping demands that severely limited the exercise of Capetian governance. The clearest examples of the process are the oaths periodically exchanged between townsfolk and lord, and oaths between the 1180s and 1315 are studied in some detail. The oaths were not merely formulae designed to reinforce a relationship between townsfolk and lord, but statements over which the Consules fought to have their lord guarantee their customary authority. Oaths were not the only means by which “loyal resistance” was practiced. Petitions for aid or impositions of taxes (invariably for military campaigns) from various lords of the town were met with demands for the expansion and/or protection of Consular prerogatives. Only at the turn of the fourteenth century did the Consules begin to align their judicial and administrative practices with those of Philip IV, an alignment that reflected both shifts in the understanding of adjudication within Toulouse and the awareness that the (re)emerging powers of the regional nobility undermined the abilities of the Consules to capture the attention of their lord.

Time-resolved infrared study of the photoinduced Wolff rearrangement and carbene intermediates

Wang, Yuhong The Johns Hopkins University 2003 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

To clarify the role of diazocarbonyl excited states in photoinduced Wolff rearrangement chemistry, time-resolved infrared (TRIR) spectroscopy has been used to study a series of acyclic and cyclic diazocarbonyl compounds and the subsequently produced carbenes. TRIR spectroscopic analysis of the growth rates of the corresponding ketene rearrangement products provided direct evidence to support the hypothesis that the reaction pathway of Wolff rearrangement is strongly influenced by the conformation of the diazo precursor. The solvent dependence of the 2-naphthyl(carbomethoxy)carbene singlet/triplet energy gap has been examined by TRIR spectroscopy and computational methods. The ground state of 2-naphthyl(carbomethoxy)carbene changes from the triplet state in hexane to the singlet state in acetonitrile. Preferential stabilization of the singlet carbene is the result of its increased dipole moment in polar solvents. This is consistent with B3LYP calculations. The effect of aromatic substitution on the singlet/triplet energy gap in substituted phenyl(carbomethoxy)carbene(X-Ph-C-COOCH₃, <bold> PCC</bold>) has been explored by TRIR spectroscopy and compared to gas-phase computational results. The absence of solvent perturbation in the TRIR spectra of <italic>p</italic>-N(CH₃)₂-<bold>PCC</bold> and parent <bold> PCC</bold> is consistent with the ground states lying >±2 kcal/mol from the next available electronic state, in line with the computational results. The observation of solvent perturbation in the TRIR spectra of <italic>p</italic>-OCH₃-<bold>PCC</bold> and <italic>p</italic>-CH₃-<bold>PCC</bold> implies that their ground states lie <±1 kcal/mol from their next available electronic state. TRIR spectroscopic study and comparison with the computational results of meta-substituted <bold>PCC</bold> species are also presented. Photoinduced Wolff rearrangement of 2-diazo-N,N-dimethyl phenyl acetamide has been studied by TRIR spectroscopy in Freon-113. NMR analysis of this diazoamide in acetonitrile with varying amounts methanol showed that the β-lactam product is formed only from the corresponding carbene and not from a diazoamide excited state. Preliminary results concerning a new diazeniumdiolate coupling methodology and TRIR spectroscopic studies of benzoyl nitrene and 2-diazo-1,3-diphenyl-1,3-propanedione are also discussed.

Is pharmacological prevention of Alzheimer's disease a realistic goal? Evidence from the Cache County Study

Zandi, Peter P The Johns Hopkins University 2002 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Growing evidence suggests that several classes of commonly used medicines may prevent the onset of Alzheimer's disease (AD). Among the most promising of these are non-steroidal anti-inflammatory drugs (NSAIDs), estrogens (HRT) and antioxidant vitamins. Other candidates include HMG-CoA reductase inhibitors (statins) and H-2 receptor antagonists (H2RAs). We examined the neuro-protective effects of these compounds in a series of cross-sectional and prospective studies using data from the Cache County Study, a longitudinal investigation of AD and other dementing illnesses among the elderly (age 65+) of Cache County, Utah (USA). In a prospective study of NSAIDs, we found that regular use of these compounds reduced the risk of developing AD. Former use appeared to afford the greatest protection, while current use was associated with little benefit unless such use extended for more than three years. Findings from a prospective study of HRT were similar. Longer durations of HRT were associated with incremental reductions in risk of AD, but current use only provided some benefit if such use exceeded ten years. In a cross-sectional study of antioxidant vitamins, we found that use of vitamins E and C together was associated with a reduced risk of AD. These findings were replicated in a preliminary analysis of prospective data. In cross-sectional studies of statins and H2RAs, we found that use of either was inversely associated with prevalence of AD. These findings, however, wore not sustained in follow-up prospective studies. There was more consistent evidence suggesting that statins that do not cross the blood-brain barrier offer greater protection than those that do. These studies support the conclusion that use of NSAIDs, HRT or antioxidant vitamins can prevent the onset of AD. In the case of NSAIDs and HRT, they may only be effective if taken at least several years prior to the onset of dementia before disease-related damage to the brain is too extensive. The only way to demonstrate the efficacy of these compounds is to conduct randomized prevention trials. Given our findings with NSAIDs and HRT, it may take several years for their protective effects to become apparent in such trials.