7 resultados para Artificial satellites in search and rescue operations.

em DRUM (Digital Repository at the University of Maryland)


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Composers from all eras and of all ethnicities explore spirituality and prayer by using one or a combination of the following ideas: having a spiritual concept in mind when composing certain pieces, quoting hymns, being influenced by their own personal beliefs, or portraying spiritual figures and ideas in their works. Some musical works are inspired by spirituality; others, as in the case of Bloch's Nigun, even serve as prayers themselves. These recitals gave me the opportunity to approach a wide variety of musical styles while discovering my own mode for expression. The unaccompanied violin works throughout this project trace a distinct lineage from the baroque to the twentieth century. Biber's appendix to the Rosary Sonatas, the Passacaglia for solo violin, is a crucial predecessor to Bach's monumental Chaconne. Eugene Ysaye was inspired to write the Six Sonatas, Op. 27 after he attended a performance of Bach's Sonatas and Partitas given by Josef Szigeti. Ysaye's second solo sonata blatantly quotes Bach's Partita No.3 in E major throughout the first movement. Every movement also contains quotations from and variations on the plainchant Dies Irae. Although each of the solo violin works presented in this project may be viewed as virtuosic concert pieces, each piece allows the performer to transcend the technical hurdles-and perhaps even utilize them-to serve a higher, artistic and spiritual purpose while alone on the concert stage. Each of the sonata works in this project requires a close, equal collaboration between violinist and pianist, rather than displaying the violinist as soloist.

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Photosynthesis –the conversion of sunlight to chemical energy –is fundamental for supporting life on our planet. Despite its importance, the physical principles that underpin the primary steps of photosynthesis, from photon absorption to electronic charge separation, remain to be understood in full. Electronic coherence within tightly-packed light-harvesting (LH) units or within individual reaction centers (RCs) has been recognized as an important ingredient for a complete understanding of the excitation energy transfer (EET) dynamics. However, the electronic coherence across units –RC and LH or LH and LH –has been consistently neglected as it does not play a significant role during these relatively slow transfer processes. Here, we turn our attention to the absorption process, which, as we will show, has a much shorter built-in timescale. We demonstrate that the- often overlooked- spatially extended but short-lived excitonic delocalization plays a relevant role in general photosynthetic systems. Most strikingly, we find that absorption intensity is, quite generally, redistributed from LH units to the RC, increasing the number of excitations which can effect charge separation without further transfer steps. A biomemetic nano-system is proposed which is predicted to funnel excitation to the RC-analogue, and hence is the first step towards exploiting these new design principles for efficient artificial light-harvesting.

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The last two decades have seen many exciting examples of tiny robots from a few cm3 to less than one cm3. Although individually limited, a large group of these robots has the potential to work cooperatively and accomplish complex tasks. Two examples from nature that exhibit this type of cooperation are ant and bee colonies. They have the potential to assist in applications like search and rescue, military scouting, infrastructure and equipment monitoring, nano-manufacture, and possibly medicine. Most of these applications require the high level of autonomy that has been demonstrated by large robotic platforms, such as the iRobot and Honda ASIMO. However, when robot size shrinks down, current approaches to achieve the necessary functions are no longer valid. This work focused on challenges associated with the electronics and fabrication. We addressed three major technical hurdles inherent to current approaches: 1) difficulty of compact integration; 2) need for real-time and power-efficient computations; 3) unavailability of commercial tiny actuators and motion mechanisms. The aim of this work was to provide enabling hardware technologies to achieve autonomy in tiny robots. We proposed a decentralized application-specific integrated circuit (ASIC) where each component is responsible for its own operation and autonomy to the greatest extent possible. The ASIC consists of electronics modules for the fundamental functions required to fulfill the desired autonomy: actuation, control, power supply, and sensing. The actuators and mechanisms could potentially be post-fabricated on the ASIC directly. This design makes for a modular architecture. The following components were shown to work in physical implementations or simulations: 1) a tunable motion controller for ultralow frequency actuation; 2) a nonvolatile memory and programming circuit to achieve automatic and one-time programming; 3) a high-voltage circuit with the highest reported breakdown voltage in standard 0.5 μm CMOS; 4) thermal actuators fabricated using CMOS compatible process; 5) a low-power mixed-signal computational architecture for robotic dynamics simulator; 6) a frequency-boost technique to achieve low jitter in ring oscillators. These contributions will be generally enabling for other systems with strict size and power constraints such as wireless sensor nodes.

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Problem This dissertation presents a literature-based framework for communication in science (with the elements partners, purposes, message, and channel), which it then applies in and amends through an empirical study of how geoscientists use two social computing technologies (SCTs), blogging and Twitter (both general use and tweeting from conferences). How are these technologies used and what value do scientists derive from them? Method The empirical part used a two-pronged qualitative study, using (1) purposive samples of ~400 blog posts and ~1000 tweets and (2) a purposive sample of 8 geoscientist interviews. Blog posts, tweets, and interviews were coded using the framework, adding new codes as needed. The results were aggregated into 8 geoscientist case studies, and general patterns were derived through cross-case analysis. Results A detailed picture of how geoscientists use blogs and twitter emerged, including a number of new functions not served by traditional channels. Some highlights: Geoscientists use SCTs for communication among themselves as well as with the public. Blogs serve persuasion and personal knowledge management; Twitter often amplifies the signal of traditional communications such as journal articles. Blogs include tutorials for peers, reviews of basic science concepts, and book reviews. Twitter includes links to readings, requests for assistance, and discussions of politics and religion. Twitter at conferences provides live coverage of sessions. Conclusions Both blogs and Twitter are routine parts of scientists' communication toolbox, blogs for in-depth, well-prepared essays, Twitter for faster and broader interactions. Both have important roles in supporting community building, mentoring, and learning and teaching. The Framework of Communication in Science was a useful tool in studying these two SCTs in this domain. The results should encourage science administrators to facilitate SCT use of scientists in their organization and information providers to search SCT documents as an important source of information.

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Theories of sparse signal representation, wherein a signal is decomposed as the sum of a small number of constituent elements, play increasing roles in both mathematical signal processing and neuroscience. This happens despite the differences between signal models in the two domains. After reviewing preliminary material on sparse signal models, I use work on compressed sensing for the electron tomography of biological structures as a target for exploring the efficacy of sparse signal reconstruction in a challenging application domain. My research in this area addresses a topic of keen interest to the biological microscopy community, and has resulted in the development of tomographic reconstruction software which is competitive with the state of the art in its field. Moving from the linear signal domain into the nonlinear dynamics of neural encoding, I explain the sparse coding hypothesis in neuroscience and its relationship with olfaction in locusts. I implement a numerical ODE model of the activity of neural populations responsible for sparse odor coding in locusts as part of a project involving offset spiking in the Kenyon cells. I also explain the validation procedures we have devised to help assess the model's similarity to the biology. The thesis concludes with the development of a new, simplified model of locust olfactory network activity, which seeks with some success to explain statistical properties of the sparse coding processes carried out in the network.

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My dissertation presented seven violin concertos in three recital programs. Three of these concertos are acknowledged masterpieces performed in established concert venues throughout the world. They are the concertos of Mozart, Beethoven and Tchaikovsky. The other four are less standard and are composed by Viotti, Kreutzer, Rode and Spohr. These less standard concertos were popular during their time yet they seem not to have stood the test of time. A curriculum devoted exclusively to the standard concertos creates problems for the young violinist. The Mozart violin concertos are often the first standard concertos that the young violin student encounters. They are considered to be the least technically demanding of the standard concertos. The next most advanced standard concertos that the student will usually encounter are Bruch’s G minor concerto, Wieniawski’s D minor concerto and Barber’s concerto. The trouble is that the work on Mozart concertos does not adequately prepare a student for the next most advanced standard concerto. There is a discontinuous leap in the progression of technical difficulty between the Mozart concertos and the next most advanced concertos. Likewise the standard concerto repertoire provides no smooth historical or stylistic progression between the Mozart concertos and the next most advanced concertos. If the young violinist is limited to the standard repertoire then she has no smooth progression either technical, historical or stylistic. I seek to demonstrate that, by adding concertos of Spohr, Viotti, Kreutzer, and Rode to the standard violin curriculum, one could remedy this problem. The first and third recitals were performed in the Gildenhorn Recital Hall and the second recital in the School of Music’s Smith Lecture Hall, both at the University of Maryland. All three recitals can be found in the Digital Repository at the University of Maryland (DRUM).

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A pressing challenge for the study of animal ethics in early modern literature is the very breadth of the category “animal,” which occludes the distinct ecological and economic roles of different species. Understanding the significance of deer to a hunter as distinct from the meaning of swine for a London pork vendor requires a historical investigation into humans’ ecological and cultural relationships with individual animals. For the constituents of England’s agricultural networks – shepherds, butchers, fishwives, eaters at tables high and low – animals matter differently. While recent scholarship on food and animal ethics often emphasizes ecological reciprocation, I insist that this mutualism is always out of balance, both across and within species lines. Focusing on drama by William Shakespeare, Ben Jonson, and the anonymous authors of late medieval biblical plays, my research investigates how sixteenth-century theaters use food animals to mediate and negotiate the complexities of a changing meat economy. On the English stage, playwrights use food animals to impress the ethico-political implications of land enclosure, forest emparkment, the search for new fisheries, and air and water pollution from urban slaughterhouses and markets. Concurrent developments in animal husbandry and theatrical production in the period thus led to new ideas about emplacement, embodiment, and the ethics of interspecies interdependence.