1,898 research outputs found
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SOAR (Support Office for Aerogeophysical Research) Annual Report 1995/1996
The Support Office for Aerogeophysical Research (SOAR) was a facility of the National Science Foundation's Office of Polar Programs whose mission is to make airborne geophysical observations available to the broad research community of geology, glaciology and other sciences. The central office of the SOAR facility is located in Austin, Texas within the University of Texas Institute for Geophysics. Other institutions with significant responsibilities are the Lamont Doherty Earth Observatory of Columbia University and the Geophysics Branch of the U.S . Geological Survey. This report summarizes the goals and accomplishments of the SOAR facility during 1995/1996 and plans for the next year.National Science Foundation's Office of Polar ProgramsInstitute for Geophysic
Integrated design of structures, controls, and materials
In this talk we shall discuss algorithms and CAD tools for the design and analysis of structures for high performance applications using advanced composite materials. An extensive mathematical theory for optimal structural (e.g., shape) design was developed over the past thirty years. Aspects of this theory have been used in the design of components for hypersonic vehicles and thermal diffusion systems based on homogeneous materials. Enhancement of the design methods to include optimization of the microstructure of the component is a significant innovation which can lead to major enhancements in component performance. Our work is focused on the adaptation of existing theories of optimal structural design (e.g., optimal shape design) to treat the design of structures using advanced composite materials (e.g., fiber reinforced, resin matrix materials). In this talk we shall discuss models and algorithms for the design of simple structures from composite materials, focussing on a problem in thermal management. We shall also discuss methods for the integration of active structural controls into the design process
Optimal Stochastic Scheduling of Power Generation Systems with Scheduling Delays and Large Cost Differentials
The optimal scheduling or unit commitment of power generation systems to meet a random demand involves the solution of a class of dynamic programming inequalities for the optimal cost and control law. We study the behavior of this optimality system in terms of two parameters: (i) a scheduling delay, e.g., the startup time of a generation unit; and (ii) the relative magnitudes of the costs (operating or starting) of different units. In the first case we show that under reasonable assumptions the optimality system has a solution for all values of the delay, and, as the delay approaches zero, that the solutions converge uniformly to those of the corresponding system with no delays. In the second case we show that as the cost of operating or starting a given machine increases relative to the costs of the other machines, there is a point beyond which the expensive machine is not used, except in extreme situations. We give a formula for the relative costs that characterize this point. Moreover, we show that as the relative cost of the expensive machine goes to infinity the optimal cost of the system including the expensive machine approaches the optimal cost of the system without the machine
Anatomy Word-Learning in Undergraduate Speech-Language Pathology Students
This study compared the effectiveness of a vocabulary list (i.e., explicit environment) to a textbook passage (i.e, authentic environment) for the initial exposure of domain-specific vocabulary from an anatomy textbook. Forty-two undergraduate Speech-Language Pathology students participated. The study\u27s materials are from Anatomy and Physiology for Speech Language and Hearing, fifth edition (Seikel et al., 2016). The selection is a subtopic on the topic of the anatomy of the cerebrum. Twenty-five vocabulary words within this section are bolded by the textbook to emphasize their importance. These words were targeted in the two different conditions, authentic (textbook) and explicit (vocabulary list). The gain scores from pretest to posttest between groups (i.e., authentic vs. explicit) were similar, and this was true of students with both high and low reading abilities, as measured by the reading score from the American College Testing (ACT). Student performance was highly variable, and many students performed poorly regardless of condition. The results of the study revealed no significant differences between participants who were in conditions that received vocabulary words within the context of a textbook or isolated in a list. This poor performance may be related to research design or student reading habits in general
Effect of forward motion on engine noise
Methods used to determine a procedure for correcting static engine data for the effects of forward motion are described. Data were analyzed from airplane flyover and static-engine tests with a JT8D-109 low-bypass-ratio turbofan engine installed on a DC-9-30, with a CF6-6D high-bypass-ratio turbofan engine installed on a DC-10-10, and with a JT9D-59A high-bypass-ratio turbofan engine installed on a DC-10-40. The observed differences between the static and the flyover data bases are discussed in terms of noise generation, convective amplification, atmospheric propagation, and engine installation. The results indicate that each noise source must be adjusted separately for forward-motion and installation effects and then projected to flight conditions as a function of source-path angle, directivity angle, and acoustic range relative to the microphones on the ground
A unique photosynthetic reaction center from Heliobacterium chlorum
AbstractA previously unknown type of photosynthetic reaction center in the brownish-green bacterium Heliobacterium chlorum is described. The reaction center is tightly bound in a highly proteinaceous undifferentiated plasma membrane and contains bacteriochlorophyll g, which has major in vivo absorbancies at 788, 576 and 370 nm. The purified membrane shows a reversible photobleaching at 798 nm; the reaction center bacteriochlorophyll g is designated P798. A reversible photobleaching at 553 nm is assigned to photooxidation of a membrane-bound c-type cytochrome. The membrane structure, pigment composition and photochemical properties suggest that H. chlorum may represent a fifth family of anoxygenic photosynthetic procaryotes
Recommended from our members
SOAR (Support Office for Aerogeophysical Research) Annual Report 1996/1997
The Support Office for Aerogeophysical Research (SOAR) was a facility of the National Science Foundation's Office of Polar Programs whose mission is to make airborne geophysical observations available to the broad research community of geology, glaciology and other sciences. The central office of the SOAR facility is located in Austin, Texas within the University of Texas Institute for Geophysics. Other institutions with significant responsibilities are the Lamont Doherty Earth Observatory of Columbia University and the Geophysics Branch of the U.S . Geological Survey. This report summarizes the goals and accomplishments of the SOAR facility during 1996/1997 and plans for the next year.National Science Foundation's Office of Polar ProgramsInstitute for Geophysic
Stability of uncertain systems.
Massachusetts Institute of Technology. Dept. of Electrical Engineering. Thesis. 1971. Ph.D.MICROFICHE COPY ALSO AVAILABLE IN BARKER ENGINEERING LIBRARY.Vita.Bibliography: leaves 119-124.Ph.D
Nonlinear and Adaptive Control of Flexible Space Structures
Introduction An important class of spacecraft missions involve deployed payload apertures attached to cantilevered flexible appendages. Dynamic response of attitude control and LOS pointing for such systems can involve nonlinear control structure interaction. A benchmark problem for slewing and pointing control of a realistic flexible spacecraft is provided by the NASA/ IEEE SCOLE design challeng
Long-lived quantum coherence in photosynthetic complexes at physiological temperature
Photosynthetic antenna complexes capture and concentrate solar radiation by
transferring the excitation to the reaction center which stores energy from the
photon in chemical bonds. This process occurs with near-perfect quantum
efficiency. Recent experiments at cryogenic temperatures have revealed that
coherent energy transfer - a wavelike transfer mechanism - occurs in many
photosynthetic pigment-protein complexes (1-4). Using the Fenna-Matthews-Olson
antenna complex (FMO) as a model system, theoretical studies incorporating both
incoherent and coherent transfer as well as thermal dephasing predict that
environmentally assisted quantum transfer efficiency peaks near physiological
temperature; these studies further show that this process is equivalent to a
quantum random walk algorithm (5-8). This theory requires long-lived quantum
coherence at room temperature, which never has been observed in FMO. Here we
present the first evidence that quantum coherence survives in FMO at
physiological temperature for at least 300 fs, long enough to perform a
rudimentary quantum computational operation. This data proves that the
wave-like energy transfer process discovered at 77 K is directly relevant to
biological function. Microscopically, we attribute this long coherence lifetime
to correlated motions within the protein matrix encapsulating the chromophores,
and we find that the degree of protection afforded by the protein appears
constant between 77 K and 277 K. The protein shapes the energy landscape and
mediates an efficient energy transfer despite thermal fluctuations. The
persistence of quantum coherence in a dynamic, disordered system under these
conditions suggests a new biomimetic strategy for designing dedicated quantum
computational devices that can operate at high temperature.Comment: PDF files, 15 pages, 3 figures (included in the PDF file
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