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Sample records for search space reduction

  1. Significant speedup of database searches with HMMs by search space reduction with PSSM family models

    PubMed Central

    Beckstette, Michael; Homann, Robert; Giegerich, Robert; Kurtz, Stefan

    2009-01-01

    Motivation: Profile hidden Markov models (pHMMs) are currently the most popular modeling concept for protein families. They provide sensitive family descriptors, and sequence database searching with pHMMs has become a standard task in today's genome annotation pipelines. On the downside, searching with pHMMs is computationally expensive. Results: We propose a new method for efficient protein family classification and for speeding up database searches with pHMMs as is necessary for large-scale analysis scenarios. We employ simpler models of protein families called position-specific scoring matrices family models (PSSM-FMs). For fast database search, we combine full-text indexing, efficient exact p-value computation of PSSM match scores and fast fragment chaining. The resulting method is well suited to prefilter the set of sequences to be searched for subsequent database searches with pHMMs. We achieved a classification performance only marginally inferior to hmmsearch, yet, results could be obtained in a fraction of runtime with a speedup of >64-fold. In experiments addressing the method's ability to prefilter the sequence space for subsequent database searches with pHMMs, our method reduces the number of sequences to be searched with hmmsearch to only 0.80% of all sequences. The filter is very fast and leads to a total speedup of factor 43 over the unfiltered search, while retaining >99.5% of the original results. In a lossless filter setup for hmmsearch on UniProtKB/Swiss-Prot, we observed a speedup of factor 92. Availability: The presented algorithms are implemented in the program PoSSuMsearch2, available for download at http://bibiserv.techfak.uni-bielefeld.de/possumsearch2/. Contact: beckstette@zbh.uni-hamburg.de Supplementary information: Supplementary data are available at Bioinformatics online. PMID:19828575

  2. Data space reduction, quality assessment and searching of seismograms: autoencoder networks for waveform data

    NASA Astrophysics Data System (ADS)

    Valentine, Andrew P.; Trampert, Jeannot

    2012-05-01

    What makes a seismogram look like a seismogram? Seismic data sets generally contain waveforms sharing some set of visual characteristics and features - indeed, seismologists routinely exploit this when performing quality control 'by hand'. Understanding and harnessing these characteristics offers the prospect of a deeper understanding of seismic waveforms, and opens up many potential new techniques for processing and working with data. In addition, the fact that certain features are shared between waveforms suggests that it may be possible to transform the data away from the time domain, and represent the same information using fewer parameters. If so, this would be a significant step towards making fully non-linear tomographic inversions computationally tractable. Hinton & Salakhutdinov showed that a particular class of neural network, termed 'autoencoder networks', may be used to find lower-dimensional encodings of complex binary data sets. Here, we adapt their work to the continuous case to allow the use of autoencoders for seismic waveforms, and offer a demonstration in which we compress 512-point waveforms to 32-element encodings. We also demonstrate that the mapping from data to encoding space, and its inverse, are well behaved, as required for many applications. Finally, we sketch a number of potential applications of the technique, which we hope will be of practical interest across all seismological disciplines, and beyond.

  3. Correspondence: Searching sequence space

    SciTech Connect

    Youvan, D.C.

    1995-08-01

    This correspondence debates the efficiency and application of genetic algorithms (GAs) to search protein sequence space. The important experimental point is that such sparse searches utilize physically realistic syntheses. In this regard, all GA-based technologies are very similar; they {open_quotes}learn{close_quotes} from their initial sparse search and then generate interesting new proteins within a few iterations. Which GA-based technology is best? That probably depends on the protein and the specific engineering goal. Given the fact that the field of combinatorial chemistry is still in its infancy, it is probably wise to consider all of the proven mutagenesis methods. 19 refs.

  4. Substructure Search by Set Reduction

    ERIC Educational Resources Information Center

    Figueras, John

    1972-01-01

    The set reduction algorithm is based on set theory and Boolean algebra rather than the graph-theoretic approach. Time trials with a small file of organic chemical structures indicate that the algorithm can be economically used for substructure (or complete structure) sequential searches on a file containing 30,000-50,000 computer-coded structures.…

  5. Quantum Search in Hilbert Space

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    2003-01-01

    A proposed quantum-computing algorithm would perform a search for an item of information in a database stored in a Hilbert-space memory structure. The algorithm is intended to make it possible to search relatively quickly through a large database under conditions in which available computing resources would otherwise be considered inadequate to perform such a task. The algorithm would apply, more specifically, to a relational database in which information would be stored in a set of N complex orthonormal vectors, each of N dimensions (where N can be exponentially large). Each vector would constitute one row of a unitary matrix, from which one would derive the Hamiltonian operator (and hence the evolutionary operator) of a quantum system. In other words, all the stored information would be mapped onto a unitary operator acting on a quantum state that would represent the item of information to be retrieved. Then one could exploit quantum parallelism: one could pose all search queries simultaneously by performing a quantum measurement on the system. In so doing, one would effectively solve the search problem in one computational step. One could exploit the direct- and inner-product decomposability of the unitary matrix to make the dimensionality of the memory space exponentially large by use of only linear resources. However, inasmuch as the necessary preprocessing (the mapping of the stored information into a Hilbert space) could be exponentially expensive, the proposed algorithm would likely be most beneficial in applications in which the resources available for preprocessing were much greater than those available for searching.

  6. The connector space reduction mechanism

    NASA Technical Reports Server (NTRS)

    Milam, M. Bruce

    1990-01-01

    The Connector Space Reduction Mechanism (CSRM) is a simple device that can reduce the number of electromechanical devices on the Payload Interface Adapter/Station Interface Adapter (PIA/SIA) from 4 to 1. The device uses simplicity to attack the heart of the connector mating problem for large interfaces. The CSRM allows blind mate connector mating with minimal alignment required over short distances. This eliminates potential interface binding problems and connector damage. The CSRM is compatible with G and H connectors and Moog Rotary Shutoff fluid couplings. The CSRM can be used also with less forgiving connectors, as was demonstrated in the lab. The CSRM is NASA-Goddard exclusive design with patent applied for. The CSRM is the correct mechanism for the PIA/SIA interface as well as other similar berthing interfaces.

  7. Space searches with a quantum robot

    SciTech Connect

    Benioff, P.

    2000-02-15

    Quantum robots are described as mobile quantum computers and ancillary systems that move in and interact with arbitrary environments. Their dynamics is given as tasks which consist of sequences of alternating computation and action phases. A task example is considered in which a quantum robot searches a space region to find the location of a system. The possibility that the search can be more efficient than a classical search is examined by considering use of Grover's Algorithm to process the search results. This is problematic for two reasons. One is the removal of entanglements generated by the (reversible) search process. The other is that (ignoring the entanglement problem), the search process in 2 dimensional space regions is no more efficient than a classical search. However quantum searches of higher dimensional space regions are more efficient than classical searches. Reasons why quantum robots are interesting independent of these results are briefly summarized.

  8. Large N reduction on coset spaces

    SciTech Connect

    Kawai, Hikaru; Shimasaki, Shinji; Tsuchiya, Asato

    2010-04-15

    As an extension of our previous work concerning the large N reduction on group manifolds, we study the large N reduction on coset spaces. We show that large N field theories on coset spaces are described by certain corresponding matrix models. We also construct Chern-Simons-like theories on group manifolds and coset spaces, and give their reduced models.

  9. The Nature of Reduction in Space Weathering

    NASA Astrophysics Data System (ADS)

    McKay, D. S.; Allen, C. C.

    1993-07-01

    Space weathering is a broad term that includes a number of complex effects of the exposure of materials to the environment of space. The processes that drive space weathering include micrometeorite impact, radiation from the Sun and cosmic rays, and exposure to the vacuum of space. One of the important effects caused by these processes is the tendency for chemical reduction of oxide and silicate materials (including glasses), with accompanying loss of oxygen and production of reduced metal. Such chemical reduction and accompanying metal production may have an important influence on the chemistry of the outermost volume of individual grains as well as on the optical properties of this material. Hapke [1] discussed five processes that have been suggested for producing submicroscopic iron metal in the lunar soil: (1) shock reduction, (2) heating in a thermal blanket in vacuum, (3) shock heating of solar-wind-impregnated grains, (4) coatings deposited by solar wind sputtering, and (5) coatings deposited by impact vaporization. As noted by Hapke, "Processes (1) and (2) have been refuted by laboratory experiments. Processes (4) and (5) have produced submicroscopic iron metal in laboratory simulations. Although no experiments have been done to simulate process (3), it is widely accepted." We have been performing experimental reduction of simulated and actual lunar materials [2-5] and have shown that, under conditions of exposure to hydrogen at elevated temperatures, reduction of FeO readily occurs in ilmenite and lunar composition glass, and occurs at a slower rate in pyroxene and olivine. Even plagioclase feldspar containing minor FeO is readily reduced with formation of metallic iron blebs on surfaces [4]. A comparison of natural lunar samples to hydrogen-reduced samples or simulants in which we are searching for reduction evidence in various soil phases is underway. Preliminary data for mature soils show, in agreement with earlier results, that reduced iron produced in

  10. Olfactory searches with limited space perception

    PubMed Central

    Masson, Jean-Baptiste

    2013-01-01

    Various insects and small animals can navigate in turbulent streams to find their mates (or food) from sparse pheromone (odor) detections. Their access to internal space perception and use of cognitive maps still are heavily debated, but for some of them, limited space perception seems to be the rule. However, this poor space perception does not prevent them from impressive search capacities. Here, as an attempt to model these behaviors, we propose a scheme that can perform, even without a detailed internal space map, searches in turbulent streams. The algorithm is based on a standardized projection of the probability of the source position to remove space perception and on the evaluation of a free energy, whose minimization along the path gives direction to the searcher. An internal “temperature” allows active control of the exploration/exploitation balance during the search. We demonstrate the efficiency of the scheme numerically, with a computational model of odor plume propagation, and experimentally, with robotic searches of thermal sources in turbulent streams. In addition to being a model to describe animals’ searches, this scheme may be applied to robotic searches in complex varying media without odometry error corrections and in problems in which active control of the exploration/exploitation balance is profitable. PMID:23803855

  11. High temperature dimensional reduction in Snyder space

    NASA Astrophysics Data System (ADS)

    Nozari, K.; Hosseinzadeh, V.; Gorji, M. A.

    2015-11-01

    In this paper, we formulate the statistical mechanics in Snyder space that supports the existence of a minimal length scale. We obtain the corresponding invariant Liouville volume which properly determines the number of microstates in the semiclassical regime. The results show that the number of accessible microstates drastically reduces at the high energy regime such that there is only one degree of freedom for a particle. Using the Liouville volume, we obtain the deformed partition function and we then study the thermodynamical properties of the ideal gas in this setup. Invoking the equipartition theorem, we show that 2/3 of the degrees of freedom freeze at the high temperature regime when the thermal de Broglie wavelength becomes of the order of the Planck length. This reduction of the number of degrees of freedom suggests an effective dimensional reduction of the space from 3 to 1 at the Planck scale.

  12. Searching Across the International Space Station Databases

    NASA Technical Reports Server (NTRS)

    Maluf, David A.; McDermott, William J.; Smith, Ernest E.; Bell, David G.; Gurram, Mohana

    2007-01-01

    Data access in the enterprise generally requires us to combine data from different sources and different formats. It is advantageous thus to focus on the intersection of the knowledge across sources and domains; keeping irrelevant knowledge around only serves to make the integration more unwieldy and more complicated than necessary. A context search over multiple domain is proposed in this paper to use context sensitive queries to support disciplined manipulation of domain knowledge resources. The objective of a context search is to provide the capability for interrogating many domain knowledge resources, which are largely semantically disjoint. The search supports formally the tasks of selecting, combining, extending, specializing, and modifying components from a diverse set of domains. This paper demonstrates a new paradigm in composition of information for enterprise applications. In particular, it discusses an approach to achieving data integration across multiple sources, in a manner that does not require heavy investment in database and middleware maintenance. This lean approach to integration leads to cost-effectiveness and scalability of data integration with an underlying schemaless object-relational database management system. This highly scalable, information on demand system framework, called NX-Search, which is an implementation of an information system built on NETMARK. NETMARK is a flexible, high-throughput open database integration framework for managing, storing, and searching unstructured or semi-structured arbitrary XML and HTML used widely at the National Aeronautics Space Administration (NASA) and industry.

  13. NASA's Orbital Space Plane Risk Reduction Strategy

    NASA Technical Reports Server (NTRS)

    Dumbacher, Dan

    2003-01-01

    This paper documents the transformation of NASA s Space Launch Initiative (SLI) Second Generation Reusable Launch Vehicle Program under the revised Integrated Space Transportation Plan, announced November 2002. Outlining the technology development approach followed by the original SLI, this paper gives insight into the current risk-reduction strategy that will enable confident development of the Nation s first orbital space plane (OSP). The OSP will perform an astronaut and contingency cargo transportation function, with an early crew rescue capability, thus enabling increased crew size and enhanced science operations aboard the International Space Station. The OSP design chosen for full-scale development will take advantage of the latest innovations American industry has to offer. The OSP Program identifies critical technologies that must be advanced to field a safe, reliable, affordable space transportation system for U.S. access to the Station and low-Earth orbit. OSP flight demonstrators will test crew safety features, validate autonomous operations, and mature thermal protection systems. Additional enabling technologies may be identified during the OSP design process as part of an overall risk-management strategy. The OSP Program uses a comprehensive and evolutionary systems acquisition approach, while applying appropriate lessons learned.

  14. The Space Technology-7 Disturbance Reduction Systems

    NASA Technical Reports Server (NTRS)

    ODonnell, James R., Jr.; Hsu, Oscar C.; Hanson, John; Hruby, Vlad

    2004-01-01

    The Space Technology 7 Disturbance Reduction System (DRS) is an in-space technology demonstration designed to validate technologies that are required for future missions such as the Laser Interferometer Space Antenna (LISA) and the Micro-Arcsecond X-ray Imaging Mission (MAXIM). The primary sensors that will be used by DRS are two Gravitational Reference Sensors (GRSs) being developed by Stanford University. DRS will control the spacecraft so that it flies about one of the freely-floating Gravitational Reference Sensor test masses, keeping it centered within its housing. The other GRS serves as a cross-reference for the first as well as being used as a reference for .the spacecraft s attitude control. Colloidal MicroNewton Thrusters being developed by the Busek Co. will be used to control the spacecraft's position and attitude using a six degree-of-freedom Dynamic Control System being developed by Goddard Space Flight Center. A laser interferometer being built by the Jet Propulsion Laboratory will be used to help validate the results of the experiment. The DRS will be launched in 2008 on the European Space Agency (ESA) LISA Pathfinder spacecraft along with a similar ESA experiment, the LISA Test Package.

  15. Model reduction for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Williams, Trevor

    1992-01-01

    Model reduction is an important practical problem in the control of flexible spacecraft, and a considerable amount of work has been carried out on this topic. Two of the best known methods developed are modal truncation and internal balancing. Modal truncation is simple to implement but can give poor results when the structure possesses clustered natural frequencies, as often occurs in practice. Balancing avoids this problem but has the disadvantages of high computational cost, possible numerical sensitivity problems, and no physical interpretation for the resulting balanced 'modes'. The purpose of this work is to examine the performance of the subsystem balancing technique developed by the investigator when tested on a realistic flexible space structure, in this case a model of the Permanently Manned Configuration (PMC) of Space Station Freedom. This method retains the desirable properties of standard balancing while overcoming the three difficulties listed above. It achieves this by first decomposing the structural model into subsystems of highly correlated modes. Each subsystem is approximately uncorrelated from all others, so balancing them separately and then combining yields comparable results to balancing the entire structure directly. The operation count reduction obtained by the new technique is considerable: a factor of roughly r(exp 2) if the system decomposes into r equal subsystems. Numerical accuracy is also improved significantly, as the matrices being operated on are of reduced dimension, and the modes of the reduced-order model now have a clear physical interpretation; they are, to first order, linear combinations of repeated-frequency modes.

  16. Exhaustive search system and method using space-filling curves

    DOEpatents

    Spires, Shannon V.

    2003-10-21

    A search system and method for one agent or for multiple agents using a space-filling curve provides a way to control one or more agents to cover an area of any space of any dimensionality using an exhaustive search pattern. An example of the space-filling curve is a Hilbert curve. The search area can be a physical geography, a cyberspace search area, or an area searchable by computing resources. The search agent can be one or more physical agents, such as a robot, and can be software agents for searching cyberspace.

  17. International Space Station (ISS) Risk Reduction Activities

    NASA Technical Reports Server (NTRS)

    Fodroci, Michael

    2011-01-01

    As the assembly of the ISS nears completion, it is worthwhile to step back and review some of the actions pursued by the Program in recent years to reduce risk and enhance the safety and health of ISS crewmembers, visitors, and space flight participants. While the ISS requirements and initial design were intended to provide the best practicable levels of safety, it is always possible to reduce risk -- given the determination and commitment to do so. The following is a summary of some of the steps taken by the ISS Program Manager, by our International Partners, by hardware and software designers, by operational specialists, and by safety personnel to continuously enhance the safety of the ISS. While decades of work went into developing the ISS requirements, there are many things in a Program like the ISS that can only be learned through actual operational experience. These risk reduction activities can be divided into roughly three categories: (1) Areas that were initially noncompliant which have subsequently been brought into compliance or near compliance (i.e., Micrometeoroid and Orbital Debris [MMOD] protection, acoustics) (2) Areas where initial design requirements were eventually considered inadequate and were subsequently augmented (i.e., Toxicity Level 4 materials, emergency hardware and procedures) (3) Areas where risks were initially underestimated, and have subsequently been addressed through additional mitigation (i.e., Extravehicular Activity [EVA] sharp edges, plasma shock hazards) Due to the hard work and cooperation of many parties working together across the span of nearly a decade, the ISS is now a safer and healthier environment for our crew, in many cases exceeding the risk reduction targets inherent in the intent of the original design. It will provide a safe and stable platform for utilization and discovery.

  18. Search for complex organic molecules in space

    NASA Astrophysics Data System (ADS)

    Ohishi, Masatoshi

    2016-07-01

    It was 1969 when the first organic molecule in space, H2CO, was discovered. Since then many organic molecules were discovered by using the NRAO 11 m (upgraded later to 12 m), Nobeyama 45 m, IRAM 30 m, and other highly sensitive radio telescopes as a result of close collaboration between radio astronomers and microwave spectroscopists. It is noteworthy that many famous organic molecules such as CH3OH, C2H5OH, (CH3)2O and CH3NH2 were detected by 1975. Organic molecules were found in so-called hot cores where molecules were thought to form on cold dust surfaces and then to evaporate by the UV photons emitted from the central star. These days organic molecules are known to exist not only in hot cores but in hot corinos (a warm, compact molecular clump found in the inner envelope of a class 0 protostar) and even protoplanetary disks. As was described above, major organic molecules were known since 1970s. It was very natural that astronomers considered a relationship between organic molecules in space and the origin of life. Several astronomers challenged to detect glycine and other prebiotic molecules without success. ALMA is expected to detect such important materials to further consider the gexogenous deliveryh hypothesis. In this paper I summarize the history in searching for complex organic molecules together with difficulties in observing very weak signals from larger species. The awfully long list of references at the end of this article may be the most useful part for readers who want to feel the exciting discovery stories.

  19. Markovian Search Games in Heterogeneous Spaces

    SciTech Connect

    Griffin, Christopher H

    2009-01-01

    We consider how to search for a mobile evader in a large heterogeneous region when sensors are used for detection. Sensors are modeled using probability of detection. Due to environmental effects, this probability will not be constant over the entire region. We map this problem to a graph search problem and, even though deterministic graph search is NP-complete, we derive a tractable, optimal, probabilistic search strategy. We do this by defining the problem as a differential game played on a Markov chain. We prove that this strategy is optimal in the sense of Nash. Simulations of an example problem illustrate our approach and verify our claims.

  20. Drag reduction of the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Ahmed, Anwar; Javed Khan, Mohammad

    1991-01-01

    Wind-tunnel and water-tunnel experiments are conducted to determine which factors contribute to the base-pressure drag experienced by the Space Shuttle Orbiter. Testing is conducted on a 4.05-percent scale model in the TAMU Water Tunnel and Low Speed Wind Tunnel with passive near-wake flow-modification devices attached in some of the tests. The devices are evaluated on the basis of effectiveness in terms of increasing the base pressure. Base pressures increase when a base cavity is introduced; a smooth cavity increases pressure by 13 percent, and when v-grooves are introduced into the cavity the pressure increases by 19 percent. When the v-groove base cavity is combined with a fairing plate, the total base pressure reaches 25 percent. The experimental results suggest that the base drag of the Space Shuttle Orbiter can be effectively reduced by the use of a base-cavity mechanism.

  1. Model reduction results for flexible space structures

    NASA Technical Reports Server (NTRS)

    Williams, Trevor; Mostarshedi, Masoud

    1993-01-01

    This paper describes the novel subsystem balancing technique for obtaining reduced-order models of flexible structures, and investigates its properties fully. This method can be regarded as a combination of the best features of modal truncation (efficiency) and internal balancing (accuracy); it is particularly well suited to the typical practical case of structures which possess clusters of close modes. Numerical results are then presented demonstrating the results obtained by applying subsystem balancing to the Air Force Phillips Laboratory ASTREX testbed, the Jet Propulsion Laboratory antenna facility, and the NASA Marshall Space Flight Center ACES structure.

  2. A search for space energy alternatives

    NASA Technical Reports Server (NTRS)

    Gilbreath, W. P.; Billman, K. W.

    1978-01-01

    This paper takes a look at a number of schemes for converting radiant energy in space to useful energy for man. These schemes are possible alternatives to the currently most studied solar power satellite concept. Possible primary collection and conversion devices discussed include the space particle flux devices, solar windmills, photovoltaic devices, photochemical cells, photoemissive converters, heat engines, dielectric energy conversion, electrostatic generators, plasma solar collectors, and thermionic schemes. Transmission devices reviewed include lasers and masers.

  3. Space shuttle search and rescue experiment using synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Sivertson, W. E., Jr.; Larson, R. W.; Zelenka, J. S.

    1977-01-01

    The feasibility of a synthetic aperture radar for search and rescue applications was demonstrated with aircraft experiments. One experiment was conducted using the ERIM four-channel radar and several test sites in the Michigan area. In this test simple corner-reflector targets were successfully imaged. Results from this investigation were positive and indicate that the concept can be used to investigate new approaches focused on the development of a global search and rescue system. An orbital experiment to demonstrate the application of synthetic aperture radar to search and rescue is proposed using the space shuttle.

  4. Gravitational wave searches using the DSN (Deep Space Network)

    NASA Technical Reports Server (NTRS)

    Nelson, S. J.; Armstrong, J. W.

    1988-01-01

    The Deep Space Network Doppler spacecraft link is currently the only method available for broadband gravitational wave searches in the 0.01 to 0.001 Hz frequency range. The DSN's role in the worldwide search for gravitational waves is described by first summarizing from the literature current theoretical estimates of gravitational wave strengths and time scales from various astrophysical sources. Current and future detection schemes for ground based and space based detectors are then discussed. Past, present, and future planned or proposed gravitational wave experiments using DSN Doppler tracking are described. Lastly, some major technical challenges to improve gravitational wave sensitivities using the DSN are discussed.

  5. Space shuttle search and rescue experiment using synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Sivertson, W. E., Jr.; Larson, R. W.; Zelenka, J. S.

    1977-01-01

    Langley Research Center, NASA, is developing a concept for using a spaceborne synthetic aperture radar with passive reflectors for search and rescue applications. The feasibility of a synthetic aperture radar for search and rescue applications has been demonstrated with aircraft experiments. One experiment was conducted using the ERIM four-channel radar and several test sites in the Michigan area. In this test simple corner-reflector targets were successfully imaged. Results from this investigation were positive and indicate that the concept can be used to investigate new approaches focused on the development of a global search and rescue system. An orbital experiment to demonstrate the application of synthetic aperture radar to search and rescue is proposed using the space shuttle.

  6. Archaeological Remote Sensing: Searching for Fort Clatsop from Space

    NASA Technical Reports Server (NTRS)

    Karsmizki, Kenneth W.; Spruce, Joe; Giardino, Marco

    2002-01-01

    The Columbia Gorge Discovery Center and NASA's Stennis Space Center have teamed up to use high-resolution aerial and satellite-based remote sensing in the search for Lewis and Clark expedition campsites. A Space Act Agreement between NASA and the Discovery Center has evolved into a study that employs remote sensing, plus modern and historical map data for relocating several Lewis and Clark encampments. Satellite data being studied include 30-meter Landsat Thematic Mapper and 1-meter Space Imaging IKONOS data. This paper includes an overview of the working relationship between NASA and the Discovery Center. It also reports on geospatial analyses of the Fort Clatsop site to demonstrate the ways geospatial technologies interface with the written and cartographic records of the expedition and how they are applied to the search for Lewis and Clark campsites.

  7. An ant colony algorithm on continuous searching space

    NASA Astrophysics Data System (ADS)

    Xie, Jing; Cai, Chao

    2015-12-01

    Ant colony algorithm is heuristic, bionic and parallel. Because of it is property of positive feedback, parallelism and simplicity to cooperate with other method, it is widely adopted in planning on discrete space. But it is still not good at planning on continuous space. After a basic introduction to the basic ant colony algorithm, we will propose an ant colony algorithm on continuous space. Our method makes use of the following three tricks. We search for the next nodes of the route according to fixed-step to guarantee the continuity of solution. When storing pheromone, it discretizes field of pheromone, clusters states and sums up the values of pheromone of these states. When updating pheromone, it makes good resolutions measured in relative score functions leave more pheromone, so that ant colony algorithm can find a sub-optimal solution in shorter time. The simulated experiment shows that our ant colony algorithm can find sub-optimal solution in relatively shorter time.

  8. Subvoxel accurate graph search using non-Euclidean graph space.

    PubMed

    Abràmoff, Michael D; Wu, Xiaodong; Lee, Kyungmoo; Tang, Li

    2014-01-01

    Graph search is attractive for the quantitative analysis of volumetric medical images, and especially for layered tissues, because it allows globally optimal solutions in low-order polynomial time. However, because nodes of graphs typically encode evenly distributed voxels of the volume with arcs connecting orthogonally sampled voxels in Euclidean space, segmentation cannot achieve greater precision than a single unit, i.e. the distance between two adjoining nodes, and partial volume effects are ignored. We generalize the graph to non-Euclidean space by allowing non-equidistant spacing between nodes, so that subvoxel accurate segmentation is achievable. Because the number of nodes and edges in the graph remains the same, running time and memory use are similar, while all the advantages of graph search, including global optimality and computational efficiency, are retained. A deformation field calculated from the volume data adaptively changes regional node density so that node density varies with the inverse of the expected cost. We validated our approach using optical coherence tomography (OCT) images of the retina and 3-D MR of the arterial wall, and achieved statistically significant increased accuracy. Our approach allows improved accuracy in volume data acquired with the same hardware, and also, preserved accuracy with lower resolution, more cost-effective, image acquisition equipment. The method is not limited to any specific imaging modality and readily extensible to higher dimensions. PMID:25314272

  9. Feature space discriminant analysis for hyperspectral data feature reduction

    NASA Astrophysics Data System (ADS)

    Imani, Maryam; Ghassemian, Hassan

    2015-04-01

    Hyperspectral images contain a large number of spectral bands that allows us to distinguish different classes with more details. But, the number of available training samples is limited. Thus, feature reduction is an important step before classification of high dimensional data. Supervised feature extraction methods such as LDA, GDA, NWFE, and MMLDA use two criteria for feature reduction: between-class scatter and within-class scatter. We propose a supervised feature extraction method in this paper that uses a new criterion in addition to two mentioned measures. The proposed method, which is called feature space discriminant analysis (FSDA), at first, maximizes the between-spectral scatter matrix to increase the difference between extracted features. In the second step, FSDA, maximizes the between-class scatter matrix and minimizes the within-class scatter matrix simultaneously. The experimental results on five popular hyperspectral images show the better performance of FSDA in comparison with other supervised feature extraction methods in small sample size situation.

  10. The Space Physics of Life: Searching for Biosignatures on Habitable Icy Worlds Affected by Space Weathering

    NASA Technical Reports Server (NTRS)

    Cooper, John F.

    2006-01-01

    Accessible surfaces of the most likely astrobiological habitats (Mars, Europa, Titan) in the solar system beyond Earth are exposed to various chemical and hydrologic weathering processes directly or indirectly induced by interaction with the overlying space environment. These processes can be both beneficial, through provision of chemical compounds and energy, and destructive, through chemical dissociation or burial, to detectable presence of biosignatures. Orbital, suborbital, and surface platforms carrying astrobiological instrumentation must survive, and preferably exploit, space environment interactions to reach these habitats and search for evidence of life or its precursors. Experience from Mars suggests that any detection of biosignatures must be accompanied by characterization of the local chemical environment and energy sources including irradiation by solar ultraviolet photons and energetic particles from the space environment. Orbital and suborbital surveys of surface chemistry and astrobiological potential in the context of the space environment should precede targeted in-situ measurements to maximize probability of biosignature detection through site selection. The Space Physics of Life (SPOL) investigation has recently been proposed to the NASA Astrobiology Institute and is briefly described in this presentation. SPOL is the astrobiologically relevant study of the interactions and relationships of potentially? or previously inhabited, bodies of the solar system with the surrounding environments. This requires an interdisciplinary effort in space physics, planetary science, and radiation biology. The proposed investigation addresses the search for habitable environments, chemical resources to support life, and techniques for detection of organic and inorganic signs of life in the context of the space environment.

  11. Systematic Dimensionality Reduction for Quantum Walks: Optimal Spatial Search and Transport on Non-Regular Graphs

    PubMed Central

    Novo, Leonardo; Chakraborty, Shantanav; Mohseni, Masoud; Neven, Hartmut; Omar, Yasser

    2015-01-01

    Continuous time quantum walks provide an important framework for designing new algorithms and modelling quantum transport and state transfer problems. Often, the graph representing the structure of a problem contains certain symmetries that confine the dynamics to a smaller subspace of the full Hilbert space. In this work, we use invariant subspace methods, that can be computed systematically using the Lanczos algorithm, to obtain the reduced set of states that encompass the dynamics of the problem at hand without the specific knowledge of underlying symmetries. First, we apply this method to obtain new instances of graphs where the spatial quantum search algorithm is optimal: complete graphs with broken links and complete bipartite graphs, in particular, the star graph. These examples show that regularity and high-connectivity are not needed to achieve optimal spatial search. We also show that this method considerably simplifies the calculation of quantum transport efficiencies. Furthermore, we observe improved efficiencies by removing a few links from highly symmetric graphs. Finally, we show that this reduction method also allows us to obtain an upper bound for the fidelity of a single qubit transfer on an XY spin network. PMID:26330082

  12. Systematic Dimensionality Reduction for Quantum Walks: Optimal Spatial Search and Transport on Non-Regular Graphs

    NASA Astrophysics Data System (ADS)

    Novo, Leonardo; Chakraborty, Shantanav; Mohseni, Masoud; Neven, Hartmut; Omar, Yasser

    2015-09-01

    Continuous time quantum walks provide an important framework for designing new algorithms and modelling quantum transport and state transfer problems. Often, the graph representing the structure of a problem contains certain symmetries that confine the dynamics to a smaller subspace of the full Hilbert space. In this work, we use invariant subspace methods, that can be computed systematically using the Lanczos algorithm, to obtain the reduced set of states that encompass the dynamics of the problem at hand without the specific knowledge of underlying symmetries. First, we apply this method to obtain new instances of graphs where the spatial quantum search algorithm is optimal: complete graphs with broken links and complete bipartite graphs, in particular, the star graph. These examples show that regularity and high-connectivity are not needed to achieve optimal spatial search. We also show that this method considerably simplifies the calculation of quantum transport efficiencies. Furthermore, we observe improved efficiencies by removing a few links from highly symmetric graphs. Finally, we show that this reduction method also allows us to obtain an upper bound for the fidelity of a single qubit transfer on an XY spin network.

  13. Pure state consciousness and its local reduction to neuronal space

    NASA Astrophysics Data System (ADS)

    Duggins, A. J.

    2013-01-01

    The single neuronal state can be represented as a vector in a complex space, spanned by an orthonormal basis of integer spike counts. In this model a scalar element of experience is associated with the instantaneous firing rate of a single sensory neuron over repeated stimulus presentations. Here the model is extended to composite neural systems that are tensor products of single neuronal vector spaces. Depiction of the mental state as a vector on this tensor product space is intended to capture the unity of consciousness. The density operator is introduced as its local reduction to the single neuron level, from which the firing rate can again be derived as the objective correlate of a subjective element. However, the relational structure of perceptual experience only emerges when the non-local mental state is considered. A metric of phenomenal proximity between neuronal elements of experience is proposed, based on the cross-correlation function of neurophysiology, but constrained by the association of theoretical extremes of correlation/anticorrelation in inseparable 2-neuron states with identical and opponent elements respectively.

  14. Reduction of Sodium in the NASA Space Food System

    NASA Technical Reports Server (NTRS)

    Kloeris, Vickie L.

    2010-01-01

    Excessive sodium content of the average American diet is an issue that is gaining more and more attention due to the implications for chronic disease and thus health care costs. The typical astronaut or cosmonaut dining on the International Space Station (ISS) is consuming even more sodium per day than the average American due to the lack of refrigeration for food and the limited amount of fresh food in the diet. NASA has known for many years that the high sodium in the on orbit diet is an exacerbating factor for the bone loss that occurs in all crew members in microgravity. However, bone loss is reversed upon return to earth normal gravity. After ten years of having US crewmembers on ISS, additional medical issues have emerged in some long duration ISS crewmembers that are not necessarily being reversed upon return to earth. While it is not necessarily thought that the high sodium content of the diet is the cause of these issues, it is thought that reducing sodium intake could potentially help alleviate some of the on orbit symptoms. Thus, there is an urgent focus on sodium reduction in space food. This paper will discuss the strategies and progress of an on-going project at NASA to reformulate the US space food system to reduce the sodium content.

  15. Localization Versus Abstraction: A Comparison of Two Search Reduction Techniques

    NASA Technical Reports Server (NTRS)

    Lansky, Amy L.

    1992-01-01

    There has been much recent work on the use of abstraction to improve planning behavior and cost. Another technique for dealing with the inherently explosive cost of planning is localization. This paper compares the relative strengths of localization and abstraction in reducing planning search cost. In particular, localization is shown to subsume abstraction. Localization techniques can model the various methods of abstraction that have been used, but also provide a much more flexible framework, with a broader range of benefits.

  16. The geometry of Niggli reduction: SAUC – search of alternative unit cells

    PubMed Central

    McGill, Keith J.; Asadi, Mojgan; Karakasheva, Maria T.; Andrews, Lawrence C.; Bernstein, Herbert J.

    2014-01-01

    A database of lattices using the G 6 representation of the Niggli-reduced cell as the search key provides a more robust and complete search than older techniques. Searching is implemented by finding the distance from the probe cell to other cells using a topological embedding of the Niggli reduction in G 6, so that all cells representing similar lattices will be found. The embedding provides the first fully linear measure of distances between unit cells. Comparison of results with those from older cell-based search algorithms suggests significant value in the new approach. PMID:24587790

  17. Subsonic drag reduction of the Space Shuttle Orbiter

    NASA Astrophysics Data System (ADS)

    Khan, Mohammad Javed; Ahmed, Anwar; Varela-Rodriguez, Edmundo

    1995-01-01

    Various near-wake flow-modifying devices were experimentally evaluated for their effectiveness in increasing base pressure of the Space Shuttle Orbiter at low subsonic speed. The results confirmed the strong three-dimensional character of the orbiter near wake. A base cavity was found to be the most effective mechanism for increasing base pressure. However, for this mechanism to be effective, the cavity had to be longer than the main engine nozzles. Surface characteristics of the base cavity exposed to freestream had a strong influence on the base pressure. The trapped-vortex mechanism due to a back step was found to be effective in increasing the base pressure only in the region of the orbital-maneuvering-system pods. A combination of base-cavity and trapped-vortex mechanisms increased the base pressure by 25%, and the reduction in total drag was approximately 6%.

  18. Reduction Potato s hydric soil erosion using space technology

    NASA Astrophysics Data System (ADS)

    Guyot, E.; Rios, V.; Zelaya, D.; Rios, E.; Lepen, F.; Padilla, P.; Soria, F.

    The potato's crop has an econ omic importance in Tucuman's agricultural PBI (Gross Product Income) because its rank is fourth(4°). Production's potato area is a breakable agro system; its geographic location is in Pedemonte's agro-ecological region so is essential to handle hydric erosion. Therefore, the aim of this work is improve crop's potato irrigation management through satellite information merge with farm's practices. The space technology consented to obtain Digital Model Soil using both unique differential and dual frequency GPS signals and total station. The irrigation practices were carried out due to irrigation management (FAO) and satellite imagine software (ENVI). Preliminary results of this experience allowed to follow the crop's growing through multitemporal study; reprogramming farm's irrigation practices intended for manage reduction hydric erosion and heighten economically its productivity for the next period

  19. Positioning Reduction of Deep Space Probes Based on VLBI Tracking

    NASA Astrophysics Data System (ADS)

    Qiao, S. B.

    2011-11-01

    ) Investigate the application of Kalman filter to the positioning reduction of deep space probes and develop related software systems. In summary, the progress in this dissertation is made in the positioning reduction of deep space probes tracked by VLBI concerning the algorithm study, software development, real observation processing and so on, while a further study is still urgent and arduous.

  20. Space program payload costs and their possible reduction

    NASA Technical Reports Server (NTRS)

    Vanvleck, E. M.; Deerwester, J. M.; Norman, S. M.; Alton, L. R.

    1973-01-01

    The possible ways by which NASA payload costs might be reduced in the future were studied. The major historical reasons for payload costs being as they were, and if there are technologies (hard and soft), or criteria for technology advances, that could significantly reduce total costs of payloads were examined. Payload costs are placed in historical context. Some historical cost breakdowns for unmanned NASA payloads are presented to suggest where future cost reductions could be most significant. Space programs of NOAA, DoD and COMSAT are then examined to ascertain if payload reductions have been brought about by the operational (as opposed to developmental) nature of such programs, economies of scale, the ability to rely on previously developed technology, or by differing management structures and attitudes. The potential impact was investigated of NASA aircraft-type management on spacecraft program costs, and some examples relating previous costs associated with aircraft costs on the one hand and manned and unmanned costs on the other are included.

  1. Long-Term International Space Station (ISS) Risk Reduction Activities

    NASA Astrophysics Data System (ADS)

    Fodroci, M. P.; Gafka, G. K.; Lutomski, M. G.; Maher, J. S.

    2012-01-01

    As the assembly of the ISS nears completion, it is worthwhile to step back and review some of the actions pursued by the Program in recent years to reduce risk and enhance the safety and health of ISS crewmembers, visitors, and space flight participants. While the initial ISS requirements and design were intended to provide the best practicable levels of safety, it is always possible to further reduce risk - given the determination, commitment, and resources to do so. The following is a summary of some of the steps taken by the ISS Program Manager, by our International Partners, by hardware and software designers, by operational specialists, and by safety personnel to continuously enhance the safety of the ISS, and to reduce risk to all crewmembers. While years of work went into the development of ISS requirements, there are many things associated with risk reduction in a Program like the ISS that can only be learned through actual operational experience. These risk reduction activities can be divided into roughly three categories: Areas that were initially noncompliant which have subsequently been brought into compliance or near compliance (i.e., Micrometeoroid and Orbital Debris [MMOD] protection, acoustics) Areas where initial design requirements were eventually considered inadequate and were subsequently augmented (i.e., Toxicity Hazard Level- 4 [THL] materials, emergency procedures, emergency equipment, control of drag-throughs) Areas where risks were initially underestimated, and have subsequently been addressed through additional mitigation (i.e., Extravehicular Activity [EVA] sharp edges, plasma shock hazards) Due to the hard work and cooperation of many parties working together across the span of more than a decade, the ISS is now a safer and healthier environment for our crew, in many cases exceeding the risk reduction targets inherent in the intent of the original design. It will provide a safe and stable platform for utilization and discovery for years

  2. Long-Term International Space Station (ISS) Risk Reduction Activities

    NASA Technical Reports Server (NTRS)

    Forroci, Michael P.; Gafka, George K.; Lutomski, Michael G.; Maher, Jacilyn S.

    2011-01-01

    As the assembly of the ISS nears completion, it is worthwhile to step back and review some of the actions pursued by the Program in recent years to reduce risk and enhance the safety and health of ISS crewmembers, visitors, and space flight participants. While the initial ISS requirements and design were intended to provide the best practicable levels of safety, it is always possible to further reduce risk given the determination, commitment, and resources to do so. The following is a summary of some of the steps taken by the ISS Program Manager, by our International Partners, by hardware and software designers, by operational specialists, and by safety personnel to continuously enhance the safety of the ISS, and to reduce risk to all crewmembers. While years of work went into the development of ISS requirements, there are many things associated with risk reduction in a Program like the ISS that can only be learned through actual operational experience. These risk reduction activities can be divided into roughly three categories: Areas that were initially noncompliant which have subsequently been brought into compliance or near compliance (i.e., Micrometeoroid and Orbital Debris [MMOD] protection, acoustics) Areas where initial design requirements were eventually considered inadequate and were subsequently augmented (i.e., Toxicity hazard level-4 materials, emergency procedures, emergency equipment, control of drag-throughs) Areas where risks were initially underestimated, and have subsequently been addressed through additional mitigation (i.e., Extravehicular Activity [EVA] sharp edges, plasma shock hazards). Due to the hard work and cooperation of many parties working together across the span of more than a decade, the ISS is now a safer and healthier environment for our crew, in many cases exceeding the risk reduction targets inherent in the intent of the original design. It will provide a safe and stable platform for utilization and discovery for years to come.

  3. Improving Peptide Identification Sensitivity in Shotgun Proteomics by Stratification of Search Space

    PubMed Central

    Alves, Gelio; Yu, Yi-Kuo

    2013-01-01

    Due to its high specificity, trypsin is the enzyme of choice in shotgun proteomics. Nonetheless, several publications do report the identification of semi-tryptic and non-tryptic peptides. Many of these peptides are conjectured to be signaling peptides or to have formed during sample preparation. It is known that only a small fraction of tandem mass spectra from a trypsin-digested protein mixture can be confidently matched to tryptic peptides. Leaving aside other possibilities such as post-translational modifications and single amino acid polymorphisms, this suggests that many unidentified spectra originate from semi-tryptic and non-tryptic peptides. To include them in database searches, however, may not improve overall peptide identification due to possible sensitivity reduction from search space expansion. To circumvent this issue for E-value based search methods, we have designed a scheme that categorizes qualified peptides ( i.e., peptides whose molecular weight differences from the parent ion are within a specified error tolerance) into three tiers: tryptic, semi-tryptic and non-tryptic. This classification allows peptides belonging to different tiers to have different Bonferroni correction factors. Our results show that this scheme can significantly improve retrieval performance when compared to search strategies that assign equal Bonferroni correction factors to all qualified peptides. PMID:23668635

  4. Space Technology 7 Disturbance Reduction System - precision control flight Validation

    NASA Technical Reports Server (NTRS)

    Carmain, Andrew J.; Dunn, Charles; Folkner, William; Hruby, Vlad; Spence, Doug; O'Donnell, James; Markley, Landis; Maghami, Peiman; Hsu, Oscar; Demmons, N.; Roy, T.; Gasdaska, C.; Young, J.; Connolly, W.; McCormick, R.; Gasdaska, C.

    2005-01-01

    The NASA New Millennium Program Space Technology 7 (ST7) project will validate technology for precision spacecraft control. The Disturbance Reduction System (DRS) will be part of the European Space Agency's LISA Pathfinder project. The DRS will control the position of the spacecraft relative to a reference to an accuracy of one nanometer over time scales of several thousand seconds. To perform the control, the spacecraft will use a new colloid thruster technology. The thrusters will operate over the range of 5 to 30 micro-Newtons with precision of 0.1 micro- Newton. The thrust will be generated by using a high electric field to extract charged droplets of a conducting colloid fluid and accelerating them with a precisely adjustable voltage. The control reference will be provided by the European LISA Technology Package, which will include two nearly freefloating test masses. The test mass positions and orientations will be measured using a capacitance bridge. The test mass position and attitude will be adjustable using electrostatically applied forces and torques. The DRS will control the spacecraft position with respect to one test mass while minimizing disturbances on the second test mass. The dynamic control system will cover eighteen degrees of freedom: six for each of the test masses and six for the spacecraft. After launch in late 2009 to a low Earth orbit, the LISA Pathfinder spacecraft will be maneuvered to a halo orbit about the Earth-Sun L1 Lagrange point for operations.

  5. Searching for Planets with the Space Interferometry Mission

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen

    2000-01-01

    The Space Interferometry Mission (SIM) will be the first space-based long baseline Michelson interferometer designed for precision astrometry. It will address a wide range of problems in stellar astrophysics and Galactic structure, delivering precision astrometry of stars down to 20 magnitude throughout the entire Galaxy. SIM uses a 10-m Michelson interferometer in Earth-trailing solar orbit to provide 4 microarcsecond (gas) precision astrometry. With a 5-year mission lifetime, SIM will be a powerful tool for discovering planets around nearby stars, through detection of the stellar reflex motion. The astrometric method complements the radial velocity technique which as already yielded many new planets, with an important benefit of directly measuring planetary masses. SIM will have a single-measurement precision of 1 microarcsecond in a frame defined by nearby reference stars, enabling searches for planets with masses as small as a few earth masses around the nearest stars. More massive planets will be detectable to much larger distances. In addition to precision astrometry SIM will also serve an important role as a technology precursor for future astrophysics missions using interferometers. Two technologies demonstrated will be high dynamic-range aperture synthesis imaging at 10-milliarcsec resolution in the optical, and fringe nulling to 10 (exp -4).

  6. Space-based Search for Transiting Exoplanets Orbiting Bright Stars

    NASA Astrophysics Data System (ADS)

    Tsvetanov, Zlatan

    At the current stage of research transiting planets hold the key to advancing our knowledge of exoplanets as they are the only targets that allow determination of many of the key plane-tary parameters. Because the employed techniques are differential (either photometry or spec-troscopy) and the planet is significantly fainter the host star the dominant limitation is simply the number of photons. This puts a very high premium on transiting planets with bright parent stars. The ExoPlanet Task Force recognized the high value of planets transiting bright stars and identified the need to perform a wide area space-based transit survey. In this presentation I will describe a program that addresses the ExoPTF recommendation by using the output of one of the instruments on the currently operating space mission STEREO. STEREO is the third mission in NASA's Solar Terrestrial Probes program. It uses two nearly identical spacecrafts -one on an Earth-leading orbit and one on an Earth-trailing orbit -each equipped with a suit of five small telescopes to provide a stereoscopic view of the coronal mass ejections (CME) as they propagate away from the Sun. As each of these telescopes observes a portion of the heliospehre, they also image the star field in the background. For the purposes of this study we will consider only the images obtained by the HI-1 instruments. Other instruments, although showing the stellar background as well, do not have the data output suitable for a search for transiting exoplanets. This project described here has the potential of delivering a number of very high value targets for follow-up studies with a wide range of facilities, both ground-based and space-based. It will provide a complete survey of all bright stars (<10m) for 18% of the sky. The photometric data series have the sensitivity to detect all transiting hot-Jupiters and other gas giants with periods up to ˜20 days and even some Neptune size planets orbiting bright and/or late type stars. On

  7. Logistics Reduction and Repurposing Technology for Long Duration Space Missions

    NASA Technical Reports Server (NTRS)

    Broyan, James L.; Chu, Andrew; Ewert, Michael K.

    2014-01-01

    One of NASA's Advanced Exploration Systems (AES) projects is the Logistics Reduction and Repurposing (LRR) project, which has the goal of reducing logistics resupply items through direct and indirect means. Various technologies under development in the project will reduce the launch mass of consumables and their packaging, enable reuse and repurposing of items and make logistics tracking more efficient. Repurposing also reduces the trash burden onboard spacecraft and indirectly reduces launch mass by replacing some items on the manifest. Examples include reuse of trash as radiation shielding or propellant. This paper provides the status of the LRR technologies in their third year of development under AES. Advanced clothing systems (ACS) are being developed to enable clothing to be worn longer, directly reducing launch mass. ACS has completed a ground exercise clothing study in preparation for an International Space Station (ISS) technology demonstration in 2014. Development of launch packaging containers and other items that can be repurposed on-orbit as part of habitation outfitting has resulted in a logistics-to-living (L2L) concept. L2L has fabricated and evaluated several multi-purpose cargo transfer bags (MCTBs) for potential reuse on orbit. Autonomous logistics management (ALM) is using radio frequency identification (RFID) to track items and thus reduce crew requirements for logistics functions. An RFID dense reader prototype is under construction and plans for integrated testing are being made. Development of a heat melt compactor (HMC) second generation unit for processing trash into compact and stable tiles is nearing completion. The HMC prototype compaction chamber has been completed and system development testing is underway. Research has been conducted on the conversion of trash-to-gas (TtG) for high levels of volume reduction and for use in propulsion systems. A steam reformation system was selected for further system definition of the TtG technology

  8. Combinatorial search for oxygen reduction reaction electrocatalysts: A review

    NASA Astrophysics Data System (ADS)

    Jeon, Min Ku; Lee, Chang Hwa; Park, Geun Il; Kang, Kweon Ho

    2012-10-01

    Oxygen reduction reaction (ORR) is one of the most interesting research issues in the academia and industries due to its importance in polymer electrolyte membrane fuel cells. Development of new ORR catalysts with low cost and high activity is under intensive research, but it is a time-consuming process because of wide range of alloys to be explored. Combinatorial synthesis and high-throughput screening techniques were suggested as new experimental approaches to accelerate the ORR electrocatalyst research. The combinatorial method is focused on the synthesis of concentrated arrays and quick evaluation of the arrays via various screening techniques. In this report, the combinatorial approaches for the ORR catalyst research were reviewed based on the screening methods. Four screening techniques of optical screening, scanning electrochemical microscopy, multielectrode half cell, and multielectrode full cell were introduced as the representative ones. Other approaches were also briefly introduced. Merits and limitations of each method were discussed and representative research results of each method were shown in detail.

  9. Hiding and Searching Strategies of Adult Humans in a Virtual and a Real-Space Room

    ERIC Educational Resources Information Center

    Talbot, Katherine J.; Legge, Eric L. G.; Bulitko, Vadim; Spetch, Marcia L.

    2009-01-01

    Adults searched for or cached three objects in nine hiding locations in a virtual room or a real-space room. In both rooms, the locations selected by participants differed systematically between searching and hiding. Specifically, participants moved farther from origin and dispersed their choices more when hiding objects than when searching for…

  10. A hybrid, self-adjusting search algorithm for optimal space trajectory design

    NASA Astrophysics Data System (ADS)

    Bolle, Andrea; Circi, Christian

    2012-08-01

    The aim of the present paper is to propose a hybrid, self adjusting, search algorithm for space trajectory optimization. By taking advantage of both direct and indirect methods, the present algorithm allows the finding of the optimal solution through the introduction of some new control parameters, whose number is smaller than that of the Lagrange multipliers, and whose range is bounded. Eventually, the optimal solution is determined by means of an iterative self-adjustment of the search domain occurring at "runtime", without any correction by an external user. This new set of parameters can be found through a reduction process of the degrees of freedom, obtained through the transversality conditions before entering the search loop. Furthermore, such a process shows that Lagrange multipliers are subject to a deep symmetry mirroring the features of the state vector. The algorithm reliability and efficiency is assessed through some test cases, and by reproducing some optimal transfer trajectories: a full three-dimensional, minimum time Mars mission, an optimal transfer to Jupiter, and finally an injection into a circular Moon orbit.

  11. Mass Reduction: The Weighty Challenge for Exploration Space Flight

    NASA Technical Reports Server (NTRS)

    Kloeris, Vickie L.

    2014-01-01

    Meeting nutritional and acceptability requirements is critical for the food system for an exploration class space mission. However, this must be achieved within the constraints of available resources such as water, crew time, stowage volume, launch mass and power availability. ? Due to resource constraints, exploration class missions are not expected to have refrigerators or freezers for food storage, and current per person food mass must be reduced to improve mission feasibility. ? The Packaged Food Mass Reduction Trade Study (Stoklosa, 2009) concluded that the mass of the current space food system can be effectively reduced by decreasing water content of certain foods and offering nutrient dense substitutes, such as meal replacement bars and beverages. Target nutrient ranges were established based on the nutritional content of the current breakfast and lunch meals in the ISS standard menu. A market survey of available commercial products produced no viable options for meal replacement bar or beverage products. New prototypes for both categories were formulated to meet target nutrient ranges. Samples of prototype products were packaged in high barrier packaging currently used for ISS and underwent an accelerated shelf life study at 31 degC and 41 degC (50% RH) for 24 weeks. Samples were assessed at the following time points: Initial, 6 weeks, 12 weeks, and 24 weeks. Testing at each time point included the following: color, texture, water activity, acceptability, and hexanal analysis (for food bars only). Proof of concept prototypes demonstrated that meal replacement food bars and beverages can deliver a comparable macronutrient profile while reducing the overall mass when compared to the ISS Standard Menu. Future work suggestions for meal replacement bars: Reformulation to include ingredients that reduce hardness and reduce browning to increase shelf life. Micronutrient analysis and potential fortification. Sensory evaluation studies including satiety tests and

  12. The Direct Imaging Search of Exoplanets from Ground and Space

    NASA Astrophysics Data System (ADS)

    Dou, Jiangpei; Ren, Deqing; Zhu, Yongtian

    2015-08-01

    Exoplanets search is one of the hottest topics in both modern astronomy and public domain. Until now over 1990 exoplanets have been confirmed mostly by the indirect radial velocity and transiting approaches, yielding several important physical information such as masses and radius. The study of the physics of planet formation and evolution will focus on giant planets through the direct imaging.However, the direct imaging of exoplanets remains challenging, due to the large flux ratio difference and the nearby angular distance. In recent years, the extreme adaptive optics (Ex-AO) coronagraphic instrumentation has been proposed and developed on 8-meter class telescopes, which is optimized for the high-contrast imaging observation from ground, for the giant exoplanets and other faint stellar companions. Gemini Planet Imager (GPI) has recently come to its first light, with a development period over 10 years. The contrast level has been pushed to 10-6. Due to the space limitation or this or other reasons, none professional adaptive optics is available for most of current 3~4 meter class telescopes, which will limit its observation power to some extent, especially in the research of high-contrast imaging of exoplanets.In this presentation, we will report the latest observation results by using our Extreme Adaptive Optics (Ex-AO) as a visiting instrument for high-contrast imaging on ESO’s 3.58-meter NTT telescope at LSO, and on 3.5-meter ARC telescope at Apache Point Observatory, respectively. It has demonstrated the Ex-AO can be used for the scientific research of exoplanets and brown dwarfs. With a update of the currect configuration with critical hardware, the dedicated instrument called as EDICT for imaging research of young giant exoplanets will be presented. Meanwhile, we have fully demonstrated in the lab a contrast on the order of 10-9 in a large detection area, which is a critical technique for future Earth-like exoplanets imaging space missions. And a space

  13. Astrometric planet search around southern ultracool dwarfs. II. Astrometric reduction methods and a deep astrometric catalogue

    NASA Astrophysics Data System (ADS)

    Lazorenko, P. F.; Sahlmann, J.; Ségransan, D.; Martín, E. L.; Mayor, M.; Queloz, D.; Udry, S.

    2014-05-01

    Aims: We describe the astrometric reduction of images obtained with the FORS2/VLT camera in the framework of an astrometric planet search around 20 M/L-transition dwarfs. We present the correction of systematic errors, the achieved astrometric performance, and a new astrometric catalogue containing the faint reference stars in 20 fields located close to the Galactic plane. Methods: Remote reference stars were used both to determine the astrometric trajectories of the nearby planet search targets and to identify and correct systematic errors. Results: We detected three types of systematic errors in the FORS2 astrometry: the relative motion of the camera's two CCD chips, errors that are correlated in space, and an error contribution of as yet unexplained origin. The relative CCD motion probably has a thermal origin and typically is 0.001-0.010 px (~0.1-1 mas), but sometimes amounts to 0.02-0.05 px (3-6 mas). This instability and space-correlated errors are detected and mitigated using reference stars. The third component of unknown origin has an amplitude of 0.03-0.14 mas and is independent of the observing conditions. We find that a consecutive sequence of 32 images of a well-exposed star over 40 min at 0.6'' seeing results in a median rms of the epoch residuals of 0.126 mas. Overall, the epoch residuals are distributed according to a normal law with a χ2 value near unity. We compiled a catalogue of 12 000 stars with I-band magnitudes of 16-22 located in 20 fields, each covering ~ 2' × 2'. It contains I-band magnitudes, ICRF positions with 40-70 mas precision, and relative proper motions and absolute trigonometric parallaxes with a precision of 0.1 mas/yr and 0.1 mas at the bright end, respectively. Conclusions: This work shows that an astrometric accuracy of ~100 micro-arcseconds over two years can be achieved with a large optical telescope in a survey covering several targets and varying observing conditions. Based on observations made with ESO telescopes at the

  14. Hubble Space Telescope Space Telescope Imaging Spectrograph Search for an Atmosphere on Callisto: A Jovian Unipolar Inductor

    NASA Astrophysics Data System (ADS)

    Strobel, Darrell F.; Saur, Joachim; Feldman, Paul D.; McGrath, Melissa A.

    2002-12-01

    Hubble Space Telescope observations of Callisto with the Space Telescope Imaging Spectrograph were performed at both eastern and western elongations to search for the UV emissions diagnostic of the presence of O2, CO2, and/or CO atmospheres. We report upper limits of 5×10-5 photons cm-2 s-1 or 15 R for a uniform disk the diameter of Callisto on emissions of O I λ1304, O I λ1356, C I λ1561, C II λ1335, and CO fourth positive bands. These upper limits yield upper bounds on O2, CO2, and CO atmospheres far in excess of the detected CO2 atmosphere by R. W. Carlson. Our results are interpreted in terms of a strong electrodynamic interaction with the Jovian magnetosphere, which drives ~1.5×105 A through Callisto's highly conducting (~104 mho) ionosphere and generates a highly reduced ionospheric electric field, severely retarded ionospheric convection (~0.1 km s-1), and a factor of ~1500 reduction in the net electron impact emission rate. Callisto's highly conducting ionosphere renders it the most tenable unipolar inductor of the Galilean satellites.

  15. On the beam direction search space in computerized non-coplanar beam angle optimization for IMRT—prostate SBRT

    NASA Astrophysics Data System (ADS)

    Rossi, Linda; Breedveld, Sebastiaan; Heijmen, Ben J. M.; Voet, Peter W. J.; Lanconelli, Nico; Aluwini, Shafak

    2012-09-01

    In a recent paper, we have published a new algorithm, designated ‘iCycle’, for fully automated multi-criterial optimization of beam angles and intensity profiles. In this study, we have used this algorithm to investigate the relationship between plan quality and the extent of the beam direction search space, i.e. the set of candidate beam directions that may be selected for generating an optimal plan. For a group of ten prostate cancer patients, optimal IMRT plans were made for stereotactic body radiation therapy (SBRT), mimicking high dose rate brachytherapy dosimetry. Plans were generated for five different beam direction input sets: a coplanar (CP) set and four non-coplanar (NCP) sets. For CP treatments, the search space consisted of 72 orientations (5° separations). The NCP CyberKnife (CK) space contained all directions available in the robotic CK treatment unit. The fully non-coplanar (F-NCP) set facilitated the highest possible degree of freedom in selecting optimal directions. CK+ and CK++ were subsets of F-NCP to investigate some aspects of the CK space. For each input set, plans were generated with up to 30 selected beam directions. Generated plans were clinically acceptable, according to an assessment of our clinicians. Convergence in plan quality occurred only after around 20 included beams. For individual patients, variations in PTV dose delivery between the five generated plans were minimal, as aimed for (average spread in V95: 0.4%). This allowed plan comparisons based on organ at risk (OAR) doses, with the rectum considered most important. Plans generated with the NCP search spaces had improved OAR sparing compared to the CP search space, especially for the rectum. OAR sparing was best with the F-NCP, with reductions in rectum DMean, V40Gy, V60Gy and D2% compared to CP of 25%, 35%, 37% and 8%, respectively. Reduced rectum sparing with the CK search space compared to F-NCP could be largely compensated by expanding CK with beams with relatively

  16. Risk Reduction for Use of Complex Devices in Space Projects

    NASA Technical Reports Server (NTRS)

    Berg, Melanie; Poivey, Christian; Friendlich, Mark; Petrick, Dave; LaBel, Kenneth; Stansberry, Scott

    2007-01-01

    We present guidel!nes to reduce risk to an acceptable level when using complex devices in space applications. Application to Virtex 4 Field Programmable Gate Array (FPGA) on Express Logistic Carrier (ELC) project is presented.

  17. Learning Problem-Solving Rules as Search through a Hypothesis Space

    ERIC Educational Resources Information Center

    Lee, Hee Seung; Betts, Shawn; Anderson, John R.

    2016-01-01

    Learning to solve a class of problems can be characterized as a search through a space of hypotheses about the rules for solving these problems. A series of four experiments studied how different learning conditions affected the search among hypotheses about the solution rule for a simple computational problem. Experiment 1 showed that a problem…

  18. Recycling and source reduction for long duration space habitation

    NASA Technical Reports Server (NTRS)

    Hightower, T. M.

    1992-01-01

    A direct mathematical approach has been established for characterizing the performance of closed-loop life support systems. The understanding that this approach gives clearly illustrates the options available for increasing the performance of a life support system by changing various parameters. New terms are defined and utilized, such as Segregation Factor, Resource Recovery Efficiency, Overall Reclamation Efficiency, Resupply Reduction Factor, and Life Support Extension Factor. The effects of increases in expendable system supplies required due to increases in life support system complexity are shown. Minimizing resupply through increased recycling and source reduction is illustrated. The effects of recycling upon resupply launch cost is also shown. Finally, material balance analyses have been performed based on quantity and composition data for both supplies and wastes, to illustrate the use of this approach by comparing ten different closed-loop life support system cases.

  19. Heuristic search in robot configuration space using variable metric

    NASA Technical Reports Server (NTRS)

    Verwer, Ben J. H.

    1987-01-01

    A method to generate obstacle free trajectories for both mobile robots and linked robots is proposed. The approach generates the shortest paths in a configuration space. The metric in the configuration space can be adjusted to obtain a tradeoff between safety and velocity by imposing extra costs on paths near obstacles.

  20. Delay reduction and optimal foraging: variable-ratio search in a foraging analogue.

    PubMed Central

    Williams, W A; Fantino, E

    1994-01-01

    The present study investigated conditions under which the conditioned reinforcement principles of delay-reduction theory and views based on simple maximization of reinforcement rate make ordinally opposing predictions with respect to foraging-related choice behavior. The use of variable-ratio schedules in the choice phase also represents an extension of delay-reduction theory to schedules that may better mimic the effort involved in searching. Pigeons responded on modified concurrent-chains schedules in which equal variable-ratio schedules led to unequal variable-interval outcomes and unequal reinforcer amounts. All 4 subjects completed a minimum of two replications of conditions for which the predictions of delay-reduction theory and a simple rate-maximizing theory were opposed. Results were consistent with delay reduction's ordinal predictions in 11 of 11 replications of the divergent predictions favoring the smaller, more immediate alternative. The predictions of rate maximization were upheld only when they were consistent with those of delay reduction. Results are discussed in terms of conditioned reinforcement, sensitivity to reductions in delay to food, and possible rules of thumb that may be useful in characterizing foraging. PMID:8207354

  1. Mapping the Color Space of Saccadic Selectivity in Visual Search

    ERIC Educational Resources Information Center

    Xu, Yun; Higgins, Emily C.; Xiao, Mei; Pomplun, Marc

    2007-01-01

    Color coding is used to guide attention in computer displays for such critical tasks as baggage screening or air traffic control. It has been shown that a display object attracts more attention if its color is more similar to the color for which one is searching. However, what does "similar" precisely mean? Can we predict the amount of attention…

  2. Bioastronautics Roadmap: A Risk Reduction Strategy for Human Space Exploration

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The Bioastronautics Critical Path Roadmap is the framework used to identify and assess the risks to crews exposed to the hazardous environments of space. It guides the implementation of research strategies to prevent or reduce those risks. Although the BCPR identifies steps that must be taken to reduce the risks to health and performance that are associated with human space flight, the BCPR is not a "critical path" analysis in the strict engineering sense. The BCPR will evolve to accommodate new information and technology development and will enable NASA to conduct a formal critical path analysis in the future. As a management tool, the BCPR provides information for making informed decisions about research priorities and resource allocation. The outcome-driven nature of the BCPR makes it amenable for assessing the focus, progress and success of the Bioastronautics research and technology program. The BCPR is also a tool for communicating program priorities and progress to the research community and NASA management.

  3. Parallel state-space search for a first solution with consistent linear speedups

    SciTech Connect

    Kale, L.V.; Saletore, V.A. )

    1989-01-01

    Consider the problem of exploring a large state-space for a goal state. Although many such states may exist in the state-space, finding any one state satisfying the requirements is sufficient. All the methods known until now for conducting such search in parallel using multiprocessors fail to provide consistent linear speedups over sequential execution. The speedups vary between sub-linear speedups over sequential execution. The speedup, giving rise to speedup anomalies reported in literature. The authors present a prioritizing strategy which yields consistent speedups that are close to P with P processors, and that monotonically increase with the addition of processors. It achieves this by keeping the total number of nodes expanded during parallel search very close to that in a sequential search. In addition, the strategy requires substantially smaller memory over other methods. The performance of this strategy is demonstrated on a multiprocessor with several state-space search problems.

  4. A search for experiments to exploit the space shuttle environment, volume 2

    NASA Technical Reports Server (NTRS)

    Fenn, J. B.

    1979-01-01

    Institutions and laboratories in India, Japan, and Western Europe which were visited during a search for experiments to exploit the space shuttle environment are described. The facilities and current research interests of the various centers are discussed with particular emphasis given to the Indian Space Research Organization.

  5. Certain integrable system on a space associated with a quantum search algorithm

    SciTech Connect

    Uwano, Y. Hino, H.; Ishiwatari, Y.

    2007-04-15

    On thinking up a Grover-type quantum search algorithm for an ordered tuple of multiqubit states, a gradient system associated with the negative von Neumann entropy is studied on the space of regular relative configurations of multiqubit states (SR{sup 2}CMQ). The SR{sup 2}CMQ emerges, through a geometric procedure, from the space of ordered tuples of multiqubit states for the quantum search. The aim of this paper is to give a brief report on the integrability of the gradient dynamical system together with quantum information geometry of the underlying space, SR{sup 2}CMQ, of that system.

  6. Linking search space structure, run-time dynamics, and problem difficulty : a step toward demystifying tabu search.

    SciTech Connect

    Whitley, L. Darrell; Howe, Adele E.; Watson, Jean-Paul

    2004-09-01

    Tabu search is one of the most effective heuristics for locating high-quality solutions to a diverse array of NP-hard combinatorial optimization problems. Despite the widespread success of tabu search, researchers have a poor understanding of many key theoretical aspects of this algorithm, including models of the high-level run-time dynamics and identification of those search space features that influence problem difficulty. We consider these questions in the context of the job-shop scheduling problem (JSP), a domain where tabu search algorithms have been shown to be remarkably effective. Previously, we demonstrated that the mean distance between random local optima and the nearest optimal solution is highly correlated with problem difficulty for a well-known tabu search algorithm for the JSP introduced by Taillard. In this paper, we discuss various shortcomings of this measure and develop a new model of problem difficulty that corrects these deficiencies. We show that Taillard's algorithm can be modeled with high fidelity as a simple variant of a straightforward random walk. The random walk model accounts for nearly all of the variability in the cost required to locate both optimal and sub-optimal solutions to random JSPs, and provides an explanation for differences in the difficulty of random versus structured JSPs. Finally, we discuss and empirically substantiate two novel predictions regarding tabu search algorithm behavior. First, the method for constructing the initial solution is highly unlikely to impact the performance of tabu search. Second, tabu tenure should be selected to be as small as possible while simultaneously avoiding search stagnation; values larger than necessary lead to significant degradations in performance.

  7. Quasi-steady state reduction of molecular motor-based models of directed intermittent search.

    PubMed

    Newby, Jay M; Bressloff, Paul C

    2010-10-01

    We present a quasi-steady state reduction of a linear reaction-hyperbolic master equation describing the directed intermittent search for a hidden target by a motor-driven particle moving on a one-dimensional filament track. The particle is injected at one end of the track and randomly switches between stationary search phases and mobile nonsearch phases that are biased in the anterograde direction. There is a finite possibility that the particle fails to find the target due to an absorbing boundary at the other end of the track. Such a scenario is exemplified by the motor-driven transport of vesicular cargo to synaptic targets located on the axon or dendrites of a neuron. The reduced model is described by a scalar Fokker-Planck (FP) equation, which has an additional inhomogeneous decay term that takes into account absorption by the target. The FP equation is used to compute the probability of finding the hidden target (hitting probability) and the corresponding conditional mean first passage time (MFPT) in terms of the effective drift velocity V, diffusivity D, and target absorption rate λ of the random search. The quasi-steady state reduction determines V, D, and λ in terms of the various biophysical parameters of the underlying motor transport model. We first apply our analysis to a simple 3-state model and show that our quasi-steady state reduction yields results that are in excellent agreement with Monte Carlo simulations of the full system under physiologically reasonable conditions. We then consider a more complex multiple motor model of bidirectional transport, in which opposing motors compete in a "tug-of-war", and use this to explore how ATP concentration might regulate the delivery of cargo to synaptic targets. PMID:20169417

  8. Determining frequentist confidence limits using a directed parameter space search

    SciTech Connect

    Daniel, Scott F.; Connolly, Andrew J.; Schneider, Jeff

    2014-10-10

    We consider the problem of inferring constraints on a high-dimensional parameter space with a computationally expensive likelihood function. We propose a machine learning algorithm that maps out the Frequentist confidence limit on parameter space by intelligently targeting likelihood evaluations so as to quickly and accurately characterize the likelihood surface in both low- and high-likelihood regions. We compare our algorithm to Bayesian credible limits derived by the well-tested Markov Chain Monte Carlo (MCMC) algorithm using both multi-modal toy likelihood functions and the seven yr Wilkinson Microwave Anisotropy Probe cosmic microwave background likelihood function. We find that our algorithm correctly identifies the location, general size, and general shape of high-likelihood regions in parameter space while being more robust against multi-modality than MCMC.

  9. Federated Space-Time Query for Earth Science Data Using OpenSearch Conventions

    NASA Astrophysics Data System (ADS)

    Lynnes, C.; Beaumont, B.; Duerr, R. E.; Hua, H.

    2009-12-01

    The past decade has seen a burgeoning of remote sensing and Earth science data providers, as evidenced in the growth of the Earth Science Information Partner (ESIP) federation. At the same time, the need to combine diverse data sets to enable understanding of the Earth as a system has also grown. While the expansion of data providers is in general a boon to such studies, the diversity presents a challenge to finding useful data for a given study. Locating all the data files with aerosol information for a particular volcanic eruption, for example, may involve learning and using several different search tools to execute the requisite space-time queries. To address this issue, the ESIP federation is developing a federated space-time query framework, based on the OpenSearch convention (www.opensearch.org), with Geo and Time extensions. In this framework, data providers publish OpenSearch Description Documents that describe in a machine-readable form how to execute queries against the provider. The novelty of OpenSearch is that the space-time query interface becomes both machine callable and easy enough to integrate into the web browser's search box. This flexibility, together with a simple REST (HTTP-get) interface, should allow a variety of data providers to participate in the federated search framework, from large institutional data centers to individual scientists. The simple interface enables trivial querying of multiple data sources and participation in recursive-like federated searches--all using the same common OpenSearch interface. This simplicity also makes the construction of clients easy, as does existing OpenSearch client libraries in a variety of languages. Moreover, a number of clients and aggregation services already exist and OpenSearch is already supported by a number of web browsers such as Firefox and Internet Explorer.

  10. Teacher Education Physical Education: In Search of a Hybrid Space

    ERIC Educational Resources Information Center

    Lynch, Timothy

    2015-01-01

    It is argued that a learning environment underpinned by a strengths-based collaborative approach between universities and schools offers extended pre-service teacher learning opportunities and subsequently enhanced preparation. The term "hybrid space" describes the ideal environment of shared partnership where knowledge is jointly…

  11. Space telescope searches for black holes in galactic nuclei

    NASA Technical Reports Server (NTRS)

    Harms, Richard J.

    1989-01-01

    The Hubble Space Telescope (HST) will allow astronomers to obtain luminosity profiles, rotation curves, and velocity dispersions at angular scales that are an order of magnitude superior to those obtained previously. This enhanced spatial resolution will greatly improve the sensitivity for detecting centrally condensed matter in nearby galactic nuclei including, possibly, black holes.

  12. Deep Space Detectives: Searching for Planets Suitable for Life

    ERIC Educational Resources Information Center

    Pallant, Amy; Damelin, Daniel; Pryputniewicz, Sarah

    2013-01-01

    This article describes the High-Adventure Science curriculum unit "Is There Life in Space?" This free online investigation, developed by The Concord Consortium, helps students see how scientists use modern tools to locate planets around distant stars and explore the probability of finding extraterrestrial life. This innovative curriculum…

  13. Searching the Force Field Electrostatic Multipole Parameter Space.

    PubMed

    Jakobsen, Sofie; Jensen, Frank

    2016-04-12

    We show by tensor decomposition analyses that the molecular electrostatic potential for amino acid peptide models has an effective rank less than twice the number of atoms. This rank indicates the number of parameters that can be derived from the electrostatic potential in a statistically significant way. Using this as a guideline, we investigate different strategies for deriving a reduced set of atomic charges, dipoles, and quadrupoles capable of reproducing the reference electrostatic potential with a low error. A full combinatorial search of selected parameter subspaces for N-methylacetamide and a cysteine peptide model indicates that there are many different parameter sets capable of providing errors close to that of the global minimum. Among the different reduced multipole parameter sets that have low errors, there is consensus that atoms involved in π-bonding require higher order multipole moments. The possible correlation between multipole parameters is investigated by exhaustive searches of combinations of up to four parameters distributed in all possible ways on all possible atomic sites. These analyses show that there is no advantage in considering combinations of multipoles compared to a simple approach where the importance of each multipole moment is evaluated sequentially. When combined with possible weighting factors related to the computational efficiency of each type of multipole moment, this may provide a systematic strategy for determining a computational efficient representation of the electrostatic component in force field calculations. PMID:26925529

  14. Active Solution Space and Search on Job-shop Scheduling Problem

    NASA Astrophysics Data System (ADS)

    Watanabe, Masato; Ida, Kenichi; Gen, Mitsuo

    In this paper we propose a new searching method of Genetic Algorithm for Job-shop scheduling problem (JSP). The coding method that represent job number in order to decide a priority to arrange a job to Gannt Chart (called the ordinal representation with a priority) in JSP, an active schedule is created by using left shift. We define an active solution at first. It is solution which can create an active schedule without using left shift, and set of its defined an active solution space. Next, we propose an algorithm named Genetic Algorithm with active solution space search (GA-asol) which can create an active solution while solution is evaluated, in order to search the active solution space effectively. We applied it for some benchmark problems to compare with other method. The experimental results show good performance.

  15. A Space Station-based search for other planetary systems

    NASA Technical Reports Server (NTRS)

    Levy, E. H.

    1986-01-01

    The physical forces shaping and maintaining the form of the solar system and disk galaxies are reviewed to define the basis for an observational campaign from the Space Station, to find other planetary systems. The evolution of the distribution of types of matter in the solar system is regarded as typical of the formation of planetary systems around other stars. The observation campaign would cover 100 stars out to 10 pc and last 15-30 yr. Technological challenges which must be met to realize the telescope on the Station are described.

  16. An algorithm for constructing and searching spaces of alternative hypotheses.

    PubMed

    Griffin, Christopher; Testa, Kelly; Racunas, Stephen

    2011-06-01

    In this paper, we develop techniques for automated hypothesis-space exploration over data sets that may contain contradictions. To do so, we make use of the equivalence between two formulations: those of first-order predicate logic with prefix modal quantifiers under the finite-model hypothesis and those of mixed-integer linear programming (MILP) problems. Unlike other approaches, we do not assume that all logical assertions are true without doubt. Instead, we look for alternative hypotheses about the validity of the claims by identifying alternative optimal solutions to a corresponding MILP. We use a collection of slack variables in the derived linear constraints to indicate the presence of contradictory data or assumptions. The objective is to minimize contradictions between data and assertions represented by the presence of nonzero slack in the set of linear constraints. In this paper, we present the following: 1) a correspondence between first-order predicate logic with modal quantifier prefixes under the finite-model hypothesis and MILP problems and 2) an implicit enumeration algorithm for exploring the contradiction hypothesis space. PMID:21147596

  17. An Algorithm for Constructing and Searching Spaces of Alternative Hypotheses

    SciTech Connect

    Testa, Kelly M; Griffin, Christopher H

    2011-01-01

    In this paper, we develop techniques for automated hypothesis-space exploration over data sets that may contain contradictions. To do so, we make use of the equivalence between two formulations: those of first-order predicate logic with prefix modal quantifiers under the finite-model hypothesis and those of mixed-integer linear programming (MILP) problems. Unlike other approaches, we do not assume that all logical assertions are true without doubt. Instead, we look for alternative hypotheses about the validity of the claims by identifying alternative optimal solutions to a corresponding MILP. We use a collection of slack variables in the derived linear constraints to indicate the presence of contradictory data or assumptions. The objective is to minimize contradictions between data and assertions represented by the presence of nonzero slack in the set of linear constraints. In this paper, we present the following: 1) a correspondence between first-order predicate logic with modal quantifier prefixes under the finite-model hypothesis and MILP problems and 2) an implicit enumeration algorithm for exploring the contradiction hypothesis space.

  18. Searching for impact craters using space shuttle photography

    NASA Technical Reports Server (NTRS)

    Wood, C. A.; Dailey, C.; Daley, W.; Wells, G.

    1984-01-01

    Extrapolation of impact cratering rates derived from Canada and Europe suggests that in the cratonic regions of Australia, India, Africa, and Brazil, 14-15 impact craters 20 km diameter should have formed during the last 120 my, and survived erosional erasure. In fact, in these areas, only 2 craters are known that approximately qualify: (1) Gosses Bluff, 22 km, 130 + or - 6 my old, and; Strangways, 24 km and 150 + or - 70 my old. It is therefore likely that about a dozen relatively large and preserved impact craters await discovery in these less explored cratons. A larger number of younger and smaller craters must also exist. An informal search is reported for impact craters using photographs obtained by Shuttle astronauts. Photographs taken with the 250 mm lens on Hassalblad cameras have a resolution of 25 m and cover a nominal area of 50x60 sq km. A larger format Linhof camera with similar resolution but 4 times larger area was flown March 1984, and will fly again in the future. Shuttle imagery has numerous advantages in looking for impact craters and for other types of Earth observations.

  19. Search for Dormant Comets in Near-Earth Space

    NASA Astrophysics Data System (ADS)

    Kim, Yoonyoung

    2013-06-01

    It is considered that comets have been injected into near-Earth space from outer region (e.g. Kuiper-belt region), providing rich volatile and organic compounds to the earth. Some comets are still active while most of them are dormant with no detectable tails and comae. Here we propose to make a multi-band photometric observation of near-Earth objects (NEOs) with comet-like orbits. We select our targets out of infrared asteroidal catalogs based on AKARI and WISE observations. With a combination of taxonomic types by Subaru observation and albedos by AKARI or WISE, we aim to dig out dormant comet candidates among NEOs. Our results will provide valuable information to figure out the dynamical evolution and fate of comets. We would like to emphasize that this is the first taxonomic survey of dormant comets to utilize the infrared data archive with AKARI and WISE.

  20. Fast space-varying convolution using matrix source coding with applications to camera stray light reduction.

    PubMed

    Wei, Jianing; Bouman, Charles A; Allebach, Jan P

    2014-05-01

    Many imaging applications require the implementation of space-varying convolution for accurate restoration and reconstruction of images. Here, we use the term space-varying convolution to refer to linear operators whose impulse response has slow spatial variation. In addition, these space-varying convolution operators are often dense, so direct implementation of the convolution operator is typically computationally impractical. One such example is the problem of stray light reduction in digital cameras, which requires the implementation of a dense space-varying deconvolution operator. However, other inverse problems, such as iterative tomographic reconstruction, can also depend on the implementation of dense space-varying convolution. While space-invariant convolution can be efficiently implemented with the fast Fourier transform, this approach does not work for space-varying operators. So direct convolution is often the only option for implementing space-varying convolution. In this paper, we develop a general approach to the efficient implementation of space-varying convolution, and demonstrate its use in the application of stray light reduction. Our approach, which we call matrix source coding, is based on lossy source coding of the dense space-varying convolution matrix. Importantly, by coding the transformation matrix, we not only reduce the memory required to store it; we also dramatically reduce the computation required to implement matrix-vector products. Our algorithm is able to reduce computation by approximately factoring the dense space-varying convolution operator into a product of sparse transforms. Experimental results show that our method can dramatically reduce the computation required for stray light reduction while maintaining high accuracy. PMID:24710398

  1. Noise reduction evaluation of grids in a supersonic air stream with application to Space Shuttle

    NASA Technical Reports Server (NTRS)

    Seiner, J. M.; Manning, J. C.; Nystrom, P.; Pao, S. P.

    1977-01-01

    Near field acoustic measurements were obtained for a model supersonic air jet perturbed by a screen. Noise reduction potential in the vicinity of the space shuttle vehicle during ground launch when the rocket exhaust flow is perturbed by a grid was determined. Both 10 and 12 mesh screens were utilized for this experiment, and each exhibited a noise reduction only at very low frequencies in the near field forward arc. A power spectrum analysis revealed that a modest reduction of from 3 to 5 decibels exists below a Strouhal number S sub t = 0.11. Above S sub t = 0.11 screen harmonics increased the observed sound pressure level. The favorable noise reductions obtained with screens for S sub t 0.11 may be of substantial interest for the space shuttle at ground launch.

  2. Federated Space-Time Query for Earth Science Data Using OpenSearch Conventions

    NASA Technical Reports Server (NTRS)

    Lynnes, Chris; Beaumont, Bruce; Duerr, Ruth; Hua, Hook

    2009-01-01

    This slide presentation reviews a Space-time query system that has been developed to assist the user in finding Earth science data that fulfills the researchers needs. It reviews the reasons why finding Earth science data can be so difficult, and explains the workings of the Space-Time Query with OpenSearch and how this system can assist researchers in finding the required data, It also reviews the developments with client server systems.

  3. Configuration space Faddeev formalism: Λ + n + n bound state search

    NASA Astrophysics Data System (ADS)

    Suslov, Vladimir; Filikhin, Igor; Vlahovic, Branislav

    2015-04-01

    The HypHI Collaboration has recently reported the evidence for bound state of Λ + n + n system (Phys. Rev. C 88, 041001(R) (2013)). However, the theoretical analysis did not find Λ3n bound state (see, for instance, Phys. Lett. B 736, 93 (2014)). In the present work we will describe our attempt to construct a phenomenological three-body ΛNN force with the spin-isospin dependence that is attractive in the channel T=1, S=1/2. This dependence was tested to reproduce the value of ground state energy for Λ3H hypernuclei. The formalism of the configuration-space Faddeev equations is applied for Λ + n + n and Λ + n + p systems. As Λ + n interaction the s-wave potential simulating model NSC97f is used. This potential reproduces well the hyperon binding energy for Λ3H nuclei (J. Phys. G: 31, 389 (2005)). The details of the model and obtained results will be presented. This work is supported by the NSF (HRD-1345219) and NASA (NNX09AV07A).

  4. Searching for the layered structure of space at the LHC.

    SciTech Connect

    Anchordoqui, L. A.; Dai, D. C.; Goldberg, H.; Landsberg, G.; Shaughnessy, G.; Stojkovic, D.; Weiler, T. J.

    2011-06-23

    Alignment of the main energy fluxes along a straight line in a target plane has been observed in families of cosmic ray particles detected in the Pamir mountains. The fraction of events with alignment is statistically significant for families with superhigh energies and large numbers of hadrons. This can be interpreted as evidence for coplanar hard scattering of secondary hadrons produced in the early stages of the atmospheric cascade development. This phenomenon can be described within the recently proposed 'crystal world,' with latticized and anisotropic spatial dimensions. Planar events are expected to dominate particle collisions at a hard-scattering energy exceeding the scale {Lambda}{sub 3} at which space transitions from 3D{r_equilibrium}2D. We study specific collider signatures that will test this hypothesis. We show that the energy spectrum of Drell-Yan (DY) scattering is significantly modified in this framework. At the LHC, two jet and three jet events are necessarily planar, but four jet events can test the hypothesis. Accordingly, we study in a model-independent way the 5{sigma} discovery reach of the ATLAS and CMS experiments for identifying four jets coplanarities. For the extreme scenario in which all pp {yields} 4 jet scattering processes become coplanar above {Lambda}{sub 3}, we show that with an integrated luminosity of 10(100) fb{sup -1} the LHC experiments have the potential to discover correlations between jets if {Lambda}{sub 3} {approx}< 1.25(1.6) TeV.

  5. Exhaustive geographic search with mobile robots along space-filling curves

    SciTech Connect

    Spires, S.V.; Goldsmith, S.Y.

    1998-03-01

    Swarms of mobile robots can be tasked with searching a geographic region for targets of interest, such as buried land mines. The authors assume that the individual robots are equipped with sensors tuned to the targets of interest, that these sensors have limited range, and that the robots can communicate with one another to enable cooperation. How can a swarm of cooperating sensate robots efficiently search a given geographic region for targets in the absence of a priori information about the target`s locations? Many of the obvious approaches are inefficient or lack robustness. One efficient approach is to have the robots traverse a space-filling curve. For many geographic search applications, this method is energy-frugal, highly robust, and provides guaranteed coverage in a finite time that decreases as the reciprocal of the number of robots sharing the search task. Furthermore, it minimizes the amount of robot-to-robot communication needed for the robots to organize their movements. This report presents some preliminary results from applying the Hilbert space-filling curve to geographic search by mobile robots.

  6. Enhanced Airport Capacity Through Safe, Dynamic Reductions in Aircraft Separation: NASA's Aircraft VOrtex Spacing System (AVOSS)

    NASA Technical Reports Server (NTRS)

    OConnor, Cornelius J.; Rutishauser, David K.

    2001-01-01

    An aspect of airport terminal operations that holds potential for efficiency improvements is the separation criteria applied to aircraft for wake vortex avoidance. These criteria evolved to represent safe spacing under weather conditions conducive to the longest wake hazards, and are consequently overly conservative during a significant portion of operations. Under many ambient conditions, such as moderate crosswinds or turbulence, wake hazard durations are substantially reduced. To realize this reduction NASA has developed a proof-of-concept Aircraft Vortex Spacing System (AVOSS). Successfully operated in a real-time field demonstration during July 2000 at the Dallas Ft. Worth International Airport, AVOSS is a novel integration of weather sensors, wake sensors, and analytical wake prediction algorithms. Gains in airport throughput using AVOSS spacing as compared to the current criteria averaged 6%, with peak values approaching the theoretical maximum of 16%. The average throughput gain translates to 15-40% reductions in delay when applied to realistic capacity ratios at major airports.

  7. Changes in the temporomandibular joint space after functional treatment of disk displacement with reduction.

    PubMed

    Ma, ZhiGui; Xie, QianYang; Yang, Chi; Zhang, ShanYong; Shen, YuQing; Cai, XieYi

    2015-03-01

    This study aimed to evaluate the changes of temporomandibularjoint (TMJ) space in the treatment of disk displacement with reduction (DDWR) for class II cases. Forty-two adolescent patients with unilateral DDWR, who were successfully treated by functional appliance, were selected in this study. Magnetic resonance imaging scans were used before treatment (T1), at the start of treatment (T2), and after functional treatment (T3). Compared with the normal joint, the change of joint space index was calculated. The anterior, posterior, and superior joint spaces were analyzed on the largest sagittal plane among T1, T2, and T3. Student's t-test was used for statistical analysis. The mean treatment period was 10 months (6-16 mo). Functional appliance was effective in eliminating pain and clicking. During the phase of T1, the value of the joint space index of DDWR was significantly higher than that of the control (P < 0.05). There was a significant decrease in the anterior space and an increase in the postsuperior space at T2 (P < 0.01), and then the contrary changes occurred at T3. However, there was a significant increase in the postsuperior space and no significant decrease in the anterior space when T1 and T3 were compared. This study indicates that the TMJ space is well distributed after disk repositioning with functional treatment of DDWR. It is also suggested that the adaptive remodeling in TMJ occurs via functional treatment. PMID:25759936

  8. The Search for Dark Matter with the Fermi Gamma Ray Space Telescope

    SciTech Connect

    Bloom, Elliott

    2011-03-30

    The Fermi Gamma-Ray Space Telescope has been scanning the gamma ray sky since it was launched by NASA in June 2008 and has a mission lifetime goal of 10 years. Largely due to our particle physics heritage, one of the main physics topics being studied by the Fermi LAT Collaboration is the search for dark matter via indirect detection. My talk will review the progress of these studies, something on how the LAT detector enables them, and expectations for the future. I will discuss both gamma-ray and (electron + positron) searches for dark matter, and some resulting theoretical implications.

  9. Flat parameter-space metric for all-sky searches for gravitational-wave pulsars

    NASA Astrophysics Data System (ADS)

    Wette, Karl; Prix, Reinhard

    2013-12-01

    All-sky, broadband, coherent searches for gravitational-wave pulsars are computationally limited. It is therefore important to make efficient use of available computational resources, notably by minimizing the number of templates used to cover the signal parameter space of sky position and frequency evolution. For searches over the sky, however, the required template density (determined by the parameter-space metric) is different at each sky position, which makes it difficult in practice to achieve an efficient covering. Previous work on this problem has found various choices of sky and frequency coordinates that render the parameter-space metric approximately constant but that are limited to coherent integration times of either less than a few days or greater than several months. These limitations restrict the sensitivity achievable by hierarchical all-sky searches and hinder the development of follow-up pipelines for interesting gravitational-wave pulsar candidates. We present a new flat parameter-space metric approximation and associated sky and frequency coordinates, which do not suffer from these limitations. Furthermore, the new metric is numerically well conditioned, which facilitates its practical use.

  10. Min-Max Spaces and Complexity Reduction in Min-Max Expansions

    SciTech Connect

    Gaubert, Stephane; McEneaney, William M.

    2012-06-15

    Idempotent methods have been found to be extremely helpful in the numerical solution of certain classes of nonlinear control problems. In those methods, one uses the fact that the value function lies in the space of semiconvex functions (in the case of maximizing controllers), and approximates this value using a truncated max-plus basis expansion. In some classes, the value function is actually convex, and then one specifically approximates with suprema (i.e., max-plus sums) of affine functions. Note that the space of convex functions is a max-plus linear space, or moduloid. In extending those concepts to game problems, one finds a different function space, and different algebra, to be appropriate. Here we consider functions which may be represented using infima (i.e., min-max sums) of max-plus affine functions. It is natural to refer to the class of functions so represented as the min-max linear space (or moduloid) of max-plus hypo-convex functions. We examine this space, the associated notion of duality and min-max basis expansions. In using these methods for solution of control problems, and now games, a critical step is complexity-reduction. In particular, one needs to find reduced-complexity expansions which approximate the function as well as possible. We obtain a solution to this complexity-reduction problem in the case of min-max expansions.

  11. Calculation reduction method for color digital holography and computer-generated hologram using color space conversion

    NASA Astrophysics Data System (ADS)

    Shimobaba, Tomoyoshi; Nagahama, Yuki; Kakue, Takashi; Takada, Naoki; Okada, Naohisa; Endo, Yutaka; Hirayama, Ryuji; Hiyama, Daisuke; Ito, Tomoyoshi

    2014-02-01

    A calculation reduction method for color digital holography (DH) and computer-generated holograms (CGHs) using color space conversion is reported. Color DH and color CGHs are generally calculated on RGB space. We calculate color DH and CGHs in other color spaces for accelerating the calculation (e.g., YCbCr color space). In YCbCr color space, a RGB image or RGB hologram is converted to the luminance component (Y), blue-difference chroma (Cb), and red-difference chroma (Cr) components. In terms of the human eye, although the negligible difference of the luminance component is well recognized, the difference of the other components is not. In this method, the luminance component is normal sampled and the chroma components are down-sampled. The down-sampling allows us to accelerate the calculation of the color DH and CGHs. We compute diffraction calculations from the components, and then we convert the diffracted results in YCbCr color space to RGB color space. The proposed method, which is possible to accelerate the calculations up to a factor of 3 in theory, accelerates the calculation over two times faster than the ones in RGB color space.

  12. Reaction engineering for materials processing in space: Reduction of ilmenite by hydrogen and carbon monoxide

    NASA Technical Reports Server (NTRS)

    Zhao, Y.; Shadman, F.

    1991-01-01

    Oxygen is a consumable material which needs to be produced continuously in most space missions. Its use for propulsion as well as life support makes oxygen one of the largest volume chemicals to be produced in space. Production of oxygen from lunar materials is of particular interest and is very attractive possibility. The kinetics and mechanism of reduction of ilmenite by carbon monoxide and hydrogen at 800 to 1100 C were investigated. The temporal profiles of conversion for carbon monoxide have a sigmoidal shape and indicate the presence of three different stages (induction, acceleration, and deceleration) during the reduction reaction. The apparent activation energy decreases from 18 kcal/mole at 10 percent conversion to 10 kcal/mole at 50 percent conversion. The reaction is first order with respect to carbon monoxide under the experimental conditions studied. Both SEM and EDX analysis show that the diffusion of Fe product away from the reaction front and through the TiO2 phase, followed by the nucleation and growth of a separate Fe phase are important steps affecting the process kinetics. The results from hydrogen reduction show that the mechanism of ilmenite reduction by hydrogen is similar to that by carbon monoxide. However, the titanium dioxide can be further reduced by hydrogen at 800 to 1000 C. The detailed comparison and theoretical modeling of both reduction processes is presented.

  13. Program documentation for the space environment test division post-test data reduction program (GNFLEX)

    NASA Technical Reports Server (NTRS)

    Jones, L. D.

    1979-01-01

    The Space Environment Test Division Post-Test Data Reduction Program processes data from test history tapes generated on the Flexible Data System in the Space Environment Simulation Laboratory at the National Aeronautics and Space Administration/Lyndon B. Johnson Space Center. The program reads the tape's data base records to retrieve the item directory conversion file, the item capture file and the process link file to determine the active parameters. The desired parameter names are read in by lead cards after which the periodic data records are read to determine parameter data level changes. The data is considered to be compressed rather than full sample rate. Tabulations and/or a tape for generating plots may be output.

  14. Reduction of the spermatogonial population in rat testes flown on Space Lab-3

    NASA Technical Reports Server (NTRS)

    Philpott, D. E.; Stevenson, J.; Corbett, R.; Sapp, W.; Williams, C.

    1985-01-01

    Quantization of the testicular spermatogonial population reduction in six rats is performed 12 hours after their return from seven days aboard Space Lab-3. The observed 7.1 percent organ weight loss, and 7.5 percent stage six spermatogonial cell population reduction in comparison with control rats correlate very well. Accurate dosimetry was not conducted on board, but radiation can not be considered the primary cause of the observed change. The decrease in protein kinase in the heart of these rats indicates that stress from adapting to weightlessness, the final jet flight, or other sources, is an important factor.

  15. The Space Shuttle Decision: NASA's Search for a Reusable Space Vehicle

    NASA Technical Reports Server (NTRS)

    Heppenheimer, T. A.

    1999-01-01

    This significant new study of the decision to build the Space Shuttle explains the Shuttle's origins and early development. In addition to internal NASA discussions, this work details the debates in the late 1960s and early 1970s among policymakers in Congress, the Air Force, and the Office of Management and Budget over the roles and technical designs of the Shuttle. Examining the interplay of these organizations with sometimes conflicting goals, the author not only explains how the world's premier space launch vehicle came into being, but also how politics can interact with science, technology, national security, and economics in national government. The weighty policy decision to build the Shuttle represents the first component of the broader story: future NASA volumes will cover the Shuttle's development and operational histories.

  16. An Experiment in Photometric Data Reduction of Rapid Candence Flare Search Data

    NASA Astrophysics Data System (ADS)

    Vander Haagen, Gary A.; Owings, Larry E.

    2014-05-01

    A process was developed to utilize a single star for both tracking and as a differential reference for high time resolution flare surveys. A data pipeline was also developed to process and merge, time stamped, high data rate target and slow data rate comparison star data for million-line files. This process reduced the data reduction time and aided in identification and analysis of photometric flare events during nightly surveys. The optical system employed a pellicle beam splitter for dual beam data collection, one path for a CCD camera for alignment, tracking, and reference and a second beam for the silicon photomultiplier collection of the target data. Typical target photometric sampling rates were 100 samples/sec. Comparison star flux and sky background was available over a continuous cycle ranging from every 1-10 seconds dependent upon the guide stars magnitude and atmospheric stability. The data pipeline yielded target flux data with corrections for sky background, detector dark count, and differential compensation. The data pipeline was successfully tested using flare search data from YY Gem where 81.6 ksec or 22.7 hours of data were collected and 1-flare detected resulting in a flare rate of 0.044 flares/hour, consistent with cited research.

  17. An Experiment in Photometric Data Reduction of Rapid Cadence Flare Search Data (Abstract)

    NASA Astrophysics Data System (ADS)

    Vander Haagen, G. A.; Owings, L. E.

    2014-12-01

    (Abstract only) A process was developed to utilize a singe star both for tracking and as a differential reference for high time resolution flare surveys. A data pipeline was also developed to process and merge, time stamped, high data rate target and slow data rate comparison star data for million-line files. This process reduced the data reduction time and aided in identification and analysis of photometric flare events during nightly surveys. The optical system employed a pellicle beam splitter for dual beam data collection, one path for a CCD camera for alignment, tracking, and reference and a second path for the silicon photomultiplier collection of the target data. Typical target photometric sampling rates were 100 samples/second. Comparison star flux and sky background was available over a continuous cycle ranging from every 1 to 10 seconds, depending upon the guide star’s magnitude and the atmospheric stability. The data pipeline yielded target flux data with corrections for sky background, detector dark count, and differential compensation. The data pipeline was successfully tested using flare search data from YY Gem, where, 81.6 ksec (22.7 hours) of data were collected and one flare detected, resulting in a flare rate of 0.044 flare/hour, consistent with cited research.

  18. Space shuttle solid rocket booster main parachute damage reduction team report

    NASA Technical Reports Server (NTRS)

    Watts, G.

    1993-01-01

    This report gives the findings of the space shuttle solid rocket booster main parachute damage reduction team. The purpose of the team was to investigate the causes of main parachute deployment damage and to recommend methods to eliminate or substantially reduce the damage. The team concluded that the two primary causes of significant damage during deployment are vent entanglement and contact of the parachutes with the main parachute support structure. As an inexpensive but effective step towards damage reduction, the team recommends modification of the parachute packing procedure to eliminate vent entanglement. As the most effective design change, the team recommends a pilot chute-deployed soft-pack system. Alternative concepts are also recommended that provide a major reduction in damage at a total cost lower than the pilot chute-deployed soft pack.

  19. A mechanism of basal spacing reduction in sodium smectitic clay materials in contact with DNAPL wastes.

    PubMed

    Ayral-Cinar, Derya; Otero-Diaz, Margarita; Demond, Avery H

    2016-09-01

    There has been concern regarding the possible attack of clays in aquitards, slurry walls and landfill liners by dense nonaqueous phase liquid (DNAPL) wastes, resulting in cracking. Despite the fact that a reduction in basal spacing in sodium smectitic clay materials has been linked to cracking, no plausible mechanism by which this reduction occurs in contact with waste DNAPLs has been formulated. To elucidate a mechanism, screening studies were conducted that showed that the combination of an anionic surfactant (AOT), a nonionic surfactant (TritonX-100) and a chlorinated solvent, tetrachloroethylene (PCE), could replicate the basal spacing reduction and cracking behavior of water-saturated bentonite caused by two waste DNAPLs obtained from the field. FTIR measurements of this system showed a displacement of the HOH bending band of water symptomatic of desiccation. Sorption measurements showed that the uptake of AOT by bentonite increased eight fold in the presence of TritonX-100 and PCE. The evidence presented here supports a mechanism of syneresis, involving the extraction of water from the interlayer space of the clay through the synergistic sorption of a nonionic and anionic surfactant mixture. It is speculated that the solvation of water in reverse micellar aggregates is the process driving the syneresis. PMID:27343864

  20. Catalytic Tar Reduction for Assistance in Thermal Conversion of Space Waste for Energy Production

    NASA Technical Reports Server (NTRS)

    Caraccio, Anne Joan; Devor, Robert William; Hintze, Paul E.; Muscatello, Anthony C.; Nur, Mononita

    2014-01-01

    The Trash to Gas (TtG) project investigates technologies for converting waste generated during spaceflight into various resources. One of these technologies was gasification, which employed a downdraft reactor designed and manufactured at NASA's Kennedy Space Center (KSC) for the conversion of simulated space trash to carbon dioxide. The carbon dioxide would then be converted to methane for propulsion and water for life support systems. A minor byproduct of gasification includes large hydrocarbons, also known as tars. Tars are unwanted byproducts that add contamination to the product stream, clog the reactor and cause complications in analysis instrumentation. The objective of this research was to perform reduction studies of a mock tar using select catalysts and choose the most effective for primary treatment within the KSC downdraft gasification reactor. Because the KSC reactor is operated at temperatures below typical gasification reactors, this study evaluates catalyst performance below recommended catalytic operating temperatures. The tar reduction experimentation was observed by passing a model tar vapor stream over the catalysts at similar conditions to that of the KSC reactor. Reduction in tar was determined using gas chromatography. Tar reduction efficiency and catalyst performances were evaluated at different temperatures.

  1. Learning Problem-Solving Rules as Search Through a Hypothesis Space.

    PubMed

    Lee, Hee Seung; Betts, Shawn; Anderson, John R

    2016-07-01

    Learning to solve a class of problems can be characterized as a search through a space of hypotheses about the rules for solving these problems. A series of four experiments studied how different learning conditions affected the search among hypotheses about the solution rule for a simple computational problem. Experiment 1 showed that a problem property such as computational difficulty of the rules biased the search process and so affected learning. Experiment 2 examined the impact of examples as instructional tools and found that their effectiveness was determined by whether they uniquely pointed to the correct rule. Experiment 3 compared verbal directions with examples and found that both could guide search. The final experiment tried to improve learning by using more explicit verbal directions or by adding scaffolding to the example. While both manipulations improved learning, learning still took the form of a search through a hypothesis space of possible rules. We describe a model that embodies two assumptions: (1) the instruction can bias the rules participants hypothesize rather than directly be encoded into a rule; (2) participants do not have memory for past wrong hypotheses and are likely to retry them. These assumptions are realized in a Markov model that fits all the data by estimating two sets of probabilities. First, the learning condition induced one set of Start probabilities of trying various rules. Second, should this first hypothesis prove wrong, the learning condition induced a second set of Choice probabilities of considering various rules. These findings broaden our understanding of effective instruction and provide implications for instructional design. PMID:26292648

  2. Target-distractor similarity has a larger impact on visual search in school-age children than spacing.

    PubMed

    Huurneman, Bianca; Boonstra, F Nienke

    2015-01-01

    In typically developing children, crowding decreases with increasing age. The influence of target-distractor similarity with respect to orientation and element spacing on visual search performance was investigated in 29 school-age children with normal vision (4- to 6-year-olds [N = 16], 7- to 8-year-olds [N = 13]). Children were instructed to search for a target E among distractor Es (feature search: all flanking Es pointing right; conjunction search: flankers in three orientations). Orientation of the target was manipulated in four directions: right (target absent), left (inversed), up, and down (vertical). Spacing was varied in four steps: 0.04°, 0.5°, 1°, and 2°. During feature search, high target-distractor similarity had a stronger impact on performance than spacing: Orientation affected accuracy until spacing was 1°, and spacing only influenced accuracy for identifying inversed targets. Spatial analyses showed that orientation affected oculomotor strategy: Children made more fixations in the "inversed" target area (4.6) than the vertical target areas (1.8 and 1.9). Furthermore, age groups differed in fixation duration: 4- to 6-year-old children showed longer fixation durations than 7- to 8-year-olds at the two largest element spacings (p = 0.039 and p = 0.027). Conjunction search performance was unaffected by spacing. Four conclusions can be drawn from this study: (a) Target-distractor similarity governs visual search performance in school-age children, (b) children make more fixations in target areas when target-distractor similarity is high, (c) 4- to 6-year-olds show longer fixation durations than 7- to 8-year-olds at 1° and 2° element spacing, and (d) spacing affects feature but not conjunction search-a finding that might indicate top-down control ameliorates crowding in children. PMID:25613761

  3. Parameter-space metric for all-sky semicoherent searches for gravitational-wave pulsars

    NASA Astrophysics Data System (ADS)

    Wette, Karl

    2015-10-01

    The sensitivity of all-sky searches for gravitational-wave pulsars is primarily limited by the finite availability of computing resources. Semicoherent searches are a widely used method of maximizing sensitivity to gravitational-wave pulsars at fixed computing cost: the data from a gravitational-wave detector are partitioned into a number of segments, each segment is coherently analyzed, and the analysis results from each segment are summed together. The generation of template banks for the coherent analysis of each segment, and for the summation, requires knowledge of the metrics associated with the coherent and semicoherent parameter spaces respectively. We present a useful approximation to the semicoherent parameter-space metric, analogous to that presented in Wette and Prix [Phys. Rev. D 88, 123005 (2013)] for the coherent metric. The new semicoherent metric is compared to previous work in Pletsch [Phys. Rev. D 82, 042002 (2010)], and Brady and Creighton [Phys. Rev. D 61, 082001 (2000)]. We find that semicoherent all-sky searches require orders of magnitude more templates than previously predicted.

  4. Analysis of the tryptic search space in UniProt databases

    PubMed Central

    Alpi, Emanuele; Griss, Johannes; da Silva, Alan Wilter Sousa; Bely, Benoit; Antunes, Ricardo; Zellner, Hermann; Ríos, Daniel; O'Donovan, Claire; Vizcaíno, Juan Antonio; Martin, Maria J

    2015-01-01

    In this article, we provide a comprehensive study of the content of the Universal Protein Resource (UniProt) protein data sets for human and mouse. The tryptic search spaces of the UniProtKB (UniProt knowledgebase) complete proteome sets were compared with other data sets from UniProtKB and with the corresponding International Protein Index, reference sequence, Ensembl, and UniRef100 (where UniRef is UniProt reference clusters) organism-specific data sets. All protein forms annotated in UniProtKB (both the canonical sequences and isoforms) were evaluated in this study. In addition, natural and disease-associated amino acid variants annotated in UniProtKB were included in the evaluation. The peptide unicity was also evaluated for each data set. Furthermore, the peptide information in the UniProtKB data sets was also compared against the available peptide-level identifications in the main MS-based proteomics repositories. Identifying the peptides observed in these repositories is an important resource of information for protein databases as they provide supporting evidence for the existence of otherwise predicted proteins. Likewise, the repositories could use the information available in UniProtKB to direct reprocessing efforts on specific sets of peptides/proteins of interest. In summary, we provide comprehensive information about the different organism-specific sequence data sets available from UniProt, together with the pros and cons for each, in terms of search space for MS-based bottom-up proteomics workflows. The aim of the analysis is to provide a clear view of the tryptic search space of UniProt and other protein databases to enable scientists to select those most appropriate for their purposes. PMID:25307260

  5. Crew autonomy for deep space exploration: Lessons from the Antarctic Search for Meteorites

    NASA Astrophysics Data System (ADS)

    Love, Stanley G.; Harvey, Ralph P.

    2014-01-01

    Future piloted missions to explore asteroids, Mars, and other targets beyond the Moon will experience strict limitations on communication between vehicles in space and control centers on Earth. These limitations will require crews to operate with greater autonomy than any past space mission has demonstrated. The Antarctic Search for Meteorites (ANSMET) project, which regularly sends small teams of researchers to remote parts of the southern continent, resembles a space mission in many ways but does not rely upon a control center. It provides a useful crew autonomy model for planners of future deep space exploration missions. In contrast to current space missions, ANSMET gives the crew the authority to adjust competing work priorities, task assignments, and daily schedules; allows the crew to be the primary monitor of mission progress; demands greater crew accountability for operational errors; requires the crew to make the most of limited communication bandwidth; adopts systems designed for simple operation and failure recovery; and grants the crew a leading role in the selection and stowage of their equipment.

  6. A strategy for residual acceleration data reduction and dissemination. [from orbiting space laboratories

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.; Alexander, J. I. D.

    1991-01-01

    A data reduction plan is being developed to efficiently process residual acceleration data from orbiting space laboratories. Implementation of the reduction plan will result in a useful, manageable accelerometer data base which can be readily employed by principal investigators during post-flight analysis of experimental results. The data reduction plan will also assist in the characterization of the acceleration environment of orbiters, which is important for the planning of future experimental missions. Prototype versions of the reduction plan are being tested using accelerometer data recorded during the Spacelab 3 (SL3) mission. Transient disturbances caused by shuttle and experiment operations and crew activities are being cataloged. The magnitudes of such disturbances can be as much as 0.01 g, but are rarely sustained for more than a fraction of a second and tend to vary greatly in orientation. It is found that the recorded frequency components of the SL3 disturbances do not exceed tolerance limits determined from modeling for a selected experiment set.

  7. The Antarctic Search for Meteorites: The Future of Space, on Earth Today - EVA Knowledge Capture Outbrief

    NASA Technical Reports Server (NTRS)

    Love, Stan

    2013-01-01

    NASA astronaut Stan Love shared his experiences with the Antarctic Search for Meteorites (ANSMET), an annual expedition to the southern continent to collect valuable samples for research in planetary science. ANSMET teams operate from isolated, remote field camps on the polar plateau, where windchill factors often reach -40 F. Several astronaut participants have noted ANSMET's similarity to a space mission. Some of the operational concepts, tools, and equipment employed by ANSMET teams may offer valuable insights to designers of future planetary surface exploration hardware.

  8. Importance of interatomic spacing in catalytic reduction of oxygen in phosphoric acid

    NASA Technical Reports Server (NTRS)

    Jalan, V.; Taylor, E. J.

    1983-01-01

    A correlation between the nearest-neighbor distance and the oxygen reduction activity of various platinum alloys is reported. It is proposed that the distance between nearest-neighbor Pt atoms on the surface of a supported catalyst is not ideal for dual site absorption of O2 or 'HO2' and that the introduction of foreign atoms which reduce the Pt nearest-neighbor spacing would result in higher oxygen reduction activity. This may allow the critical 0-0 bond interatomic distance and hence the optimum Pt-Pt separation for bond rupture to be determined from quantum chemical calculations. A composite analysis shows that the data on supported Pt alloys are consistent with Appleby's (1970) data on bulk metals with respect to specific activity, activation energy, preexponential factor, and percent d-band character.

  9. Impact of scale space search on age- and gender-related changes in MRI-based cortical morphometry.

    PubMed

    Zhao, Lu; Boucher, Maxime; Rosa-Neto, Pedro; Evans, Alan C

    2013-09-01

    In magnetic resonance imaging based brain morphometry, Gaussian smoothing is often applied to increase the signal-to-noise ratio and to increase the detection power of statistical parametric maps. However, most existing studies used a single smoothing filter without adequately justifying their choices. In this article, we want to determine the extent for which performing a morphometry analysis using multiple smoothing filters, namely conducting a scale space search, improves or decreases the detection power. We first compared scale space search with single-filter analysis through a simulated population study. The multiple comparisons in our four-dimensional scale space searches were corrected for using a unified P-value approach. Our results illustrate that, compared with a single-filter analysis, a scale space search analysis can properly capture the variations in analysis results caused by variations in smoothing, and more importantly, it can obviously increase the sensitivity for detecting brain morphometric changes. We also show that the cost of an increased critical threshold for conducting a scale space search is very small. In the second experiment, we investigated age and gender effects on cortical volume, thickness, and surface area in 104 normal subjects using scale space search. The obtained results provide a perspective of scale space theory on the morphological changes with age and gender. These results suggest that, in exploratory studies of aging, gender, and disease, conducting a scale space search is essential, if we are to produce a complete description of the structural changes or abnormalities associated with these dimensions. PMID:22422546

  10. The Space Technology-7 Disturbance Reduction System Precision Control Flight Validation Experiment Control System Design

    NASA Technical Reports Server (NTRS)

    O'Donnell, James R.; Hsu, Oscar C.; Maghami, Peirman G.; Markley, F. Landis

    2006-01-01

    As originally proposed, the Space Technology-7 Disturbance Reduction System (DRS) project, managed out of the Jet Propulsion Laboratory, was designed to validate technologies required for future missions such as the Laser Interferometer Space Antenna (LISA). The two technologies to be demonstrated by DRS were Gravitational Reference Sensors (GRSs) and Colloidal MicroNewton Thrusters (CMNTs). Control algorithms being designed by the Dynamic Control System (DCS) team at the Goddard Space Flight Center would control the spacecraft so that it flew about a freely-floating GRS test mass, keeping it centered within its housing. For programmatic reasons, the GRSs were descoped from DRS. The primary goals of the new mission are to validate the performance of the CMNTs and to demonstrate precise spacecraft position control. DRS will fly as a part of the European Space Agency (ESA) LISA Pathfinder (LPF) spacecraft along with a similar ESA experiment, the LISA Technology Package (LTP). With no GRS, the DCS attitude and drag-free control systems make use of the sensor being developed by ESA as a part of the LTP. The control system is designed to maintain the spacecraft s position with respect to the test mass, to within 10 nm/the square root of Hz over the DRS science frequency band of 1 to 30 mHz.

  11. Searching for Faint Companions to Nearby Stars with the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Schroeder, Daniel J.; Golimowski, David A.

    1996-01-01

    A search for faint companions (FC's) to selected stars within 5 pc of the Sun using the Hubble Space Telescope's Planetary Camera (PC) has been initiated. To assess the PC's ability to detect FCs, we have constructed both model and laboratory-simulated images and compared them to actual PC images. We find that the PC's point-spread function (PSF) is 3-4 times brighter over the angular range 2-5 sec than the PSF expected for a perfect optical system. Azimuthal variations of the PC's PSF are 10-20 times larger than expected for a perfect PSF. These variations suggest that light is scattered nonuniformly from the surface of the detector. Because the anomalies in the PC's PSF cannot be precisely simulated, subtracting a reference PSF from the PC image is problematic. We have developed a computer algorithm that identifies local brightness anomalies within the PSF as potential FCs. We find that this search algorithm will successfully locate FCs anywhere within the circumstellar field provided that the average pixel signal from the FC is at least 10 sigma above the local background. This detection limit suggests that a comprehensive search for extrasolar Jovian planets with the PC is impractical. However, the PC is useful for detecting other types of substellar objects. With a stellar signal of 10(exp 9) e(-), for example, we may detect brown dwarfs as faint as M(sub I) = 16.7 separated by 1 sec from alpha Cen A.

  12. Exploration an the Search for Origins: A Vision for Ultraviolet-Optical-Infrared Space Astronomy

    NASA Technical Reports Server (NTRS)

    Dressler, Alan (Editor); Brown, Robert A.; Davidsen, Arthur F.; Ellis, Richard S.; Freedman, Wendy L.; Green, Richard F.; Hauser, Michael G.; Kirshner, Robert P.; Kulkarni, Shrinivas; Lilly, Simon J.; Margon, Bruce H.; Porco, Carolyn C.; Richstone, Douglas O.; Stockman, H. S.; Thronson, Harley A., Jr.; Tonry, John L.; Truran, James; Weiler, Edward J.

    1996-01-01

    Public support and enthusiasm for astronomy have been strong in the final decades of the twentieth century. Nowhere is this better demonstrated than with the Hubble Space Telescope (HCT), a grand endeavor, which is enabling astronomers to make giant strides in understanding our universe, our place in it, and our relation to it. The NASAs first infrared observatory, the Space Infrared Telescope Facility (SIRTF), promises to take the crucial next steps towards understanding the formation of stars and galaxies. Toward their completion, the HST and Beyond Committee identifies major goals, whose accomplishment will justify a commitment well into the next century: (1) the detailed study of the birth and evolution of normal galaxies such as the Milky Way; (2) the detection of Earth-like planets around other stars and the search for evidence of life on them; (3) NASA should develop a space observatory of aperture 4m or larger, optimized for imaging and spectroscopy over the wavelength range 1-5 microns; and (4) NASA should develop the capability for space interferometry.

  13. Direct-to-digital holography reduction of reference hologram noise and fourier space smearing

    DOEpatents

    Voelkl, Edgar

    2006-06-27

    Systems and methods are described for reduction of reference hologram noise and reduction of Fourier space smearing, especially in the context of direct-to-digital holography (off-axis interferometry). A method of reducing reference hologram noise includes: recording a plurality of reference holograms; processing the plurality of reference holograms into a corresponding plurality of reference image waves; and transforming the corresponding plurality of reference image waves into a reduced noise reference image wave. A method of reducing smearing in Fourier space includes: recording a plurality of reference holograms; processing the plurality of reference holograms into a corresponding plurality of reference complex image waves; transforming the corresponding plurality of reference image waves into a reduced noise reference complex image wave; recording a hologram of an object; processing the hologram of the object into an object complex image wave; and dividing the complex image wave of the object by the reduced noise reference complex image wave to obtain a reduced smearing object complex image wave.

  14. Never Use the Complete Search Space: a Concept to Enhance the Optimization Procedure for Monitoring Networks

    NASA Astrophysics Data System (ADS)

    Bode, F.; Reuschen, S.; Nowak, W.

    2015-12-01

    Drinking-water well catchments include many potential sources of contaminations like gas stations or agriculture. Finding optimal positions of early-warning monitoring wells is challenging because there are various parameters (and their uncertainties) that influence the reliability and optimality of any suggested monitoring location or monitoring network.The overall goal of this project is to develop and establish a concept to assess, design and optimize early-warning systems within well catchments. Such optimal monitoring networks need to optimize three competing objectives: a high detection probability, which can be reached by maximizing the "field of vision" of the monitoring network, a long early-warning time such that there is enough time left to install counter measures after first detection, and the overall operating costs of the monitoring network, which should ideally be reduced to a minimum. The method is based on numerical simulation of flow and transport in heterogeneous porous media coupled with geostatistics and Monte-Carlo, scenario analyses for real data, respectively, wrapped up within the framework of formal multi-objective optimization using a genetic algorithm.In order to speed up the optimization process and to better explore the Pareto-front, we developed a concept that forces the algorithm to search only in regions of the search space where promising solutions can be expected. We are going to show how to define these regions beforehand, using knowledge of the optimization problem, but also how to define them independently of problem attributes. With that, our method can be used with and/or without detailed knowledge of the objective functions.In summary, our study helps to improve optimization results in less optimization time by meaningful restrictions of the search space. These restrictions can be done independently of the optimization problem, but also in a problem-specific manner.

  15. NASA's Space Launch System Advanced Booster Engineering Demonstration and Risk Reduction Efforts

    NASA Technical Reports Server (NTRS)

    Crumbly, Christopher M.; May, Todd; Dumbacher, Daniel

    2012-01-01

    The National Aeronautics and Space Administration (NASA) formally initiated the Space Launch System (SLS) development in September 2011, with the approval of the program s acquisition plan, which engages the current workforce and infrastructure to deliver an initial 70 metric ton (t) SLS capability in 2017, while using planned block upgrades to evolve to a full 130 t capability after 2021. A key component of the acquisition plan is a three-phased approach for the first stage boosters. The first phase is to complete the development of the Ares and Space Shuttle heritage 5-segment solid rocket boosters for initial exploration missions in 2017 and 2021. The second phase in the booster acquisition plan is the Advanced Booster Risk Reduction and/or Engineering Demonstration NASA Research Announcement (NRA), which was recently awarded after a full and open competition. The NRA was released to industry on February 9, 2012, and its stated intent was to reduce risks leading to an affordable Advanced Booster and to enable competition. The third and final phase will be a full and open competition for Design, Development, Test, and Evaluation (DDT&E) of the Advanced Boosters. There are no existing boosters that can meet the performance requirements for the 130 t class SLS. The expected thrust class of the Advanced Boosters is potentially double the current 5-segment solid rocket booster capability. These new boosters will enable the flexible path approach to space exploration beyond Earth orbit, opening up vast opportunities including near-Earth asteroids, Lagrange Points, and Mars. This evolved capability offers large volume for science missions and payloads, will be modular and flexible, and will be right-sized for mission requirements. NASA developed the Advanced Booster Engineering Demonstration and/or Risk Reduction NRA to seek industry participation in reducing risks leading to an affordable Advanced Booster that meets the SLS performance requirements. Demonstrations and

  16. NASA's Space Launch System Advanced Booster Engineering Demonstration and/or Risk Reduction Efforts

    NASA Technical Reports Server (NTRS)

    Crumbly, Christopher M.; Dumbacher, Daniel L.; May, Todd A.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) formally initiated the Space Launch System (SLS) development in September 2011, with the approval of the program s acquisition plan, which engages the current workforce and infrastructure to deliver an initial 70 metric ton (t) SLS capability in 2017, while using planned block upgrades to evolve to a full 130 t capability after 2021. A key component of the acquisition plan is a three-phased approach for the first stage boosters. The first phase is to complete the development of the Ares and Space Shuttle heritage 5-segment solid rocket boosters (SRBs) for initial exploration missions in 2017 and 2021. The second phase in the booster acquisition plan is the Advanced Booster Risk Reduction and/or Engineering Demonstration NASA Research Announcement (NRA), which was recently awarded after a full and open competition. The NRA was released to industry on February 9, 2012, with a stated intent to reduce risks leading to an affordable advanced booster and to enable competition. The third and final phase will be a full and open competition for Design, Development, Test, and Evaluation (DDT&E) of the advanced boosters. There are no existing boosters that can meet the performance requirements for the 130 t class SLS. The expected thrust class of the advanced boosters is potentially double the current 5-segment solid rocket booster capability. These new boosters will enable the flexible path approach to space exploration beyond Earth orbit (BEO), opening up vast opportunities including near-Earth asteroids, Lagrange Points, and Mars. This evolved capability offers large volume for science missions and payloads, will be modular and flexible, and will be right-sized for mission requirements. NASA developed the Advanced Booster Engineering Demonstration and/or Risk Reduction NRA to seek industry participation in reducing risks leading to an affordable advanced booster that meets the SLS performance requirements

  17. InP based solar cells for space application: Reduction of external losses

    NASA Technical Reports Server (NTRS)

    Wu, X.; Coutts, T. J.; Dhere, R. G.; Gessert, T. A.; Dhere, N. G.

    1987-01-01

    Although InP-based solar cells have considerable potential for space applications, it is necessary to improve efficiencies to around the level of GaAs or Si cells before their excellent radiation resistance can be regarded as a dominant advantage. The authors concentrate on indium-tin-oxide/InP cells, presenting data relating to reduction of the contact resistance of the rear surface metallization, reduction of reflectance losses by choosing indium-tin-oxide deposition conditions to give specific optical properties, and reduction of losses associated with the grid. Simultaneous optimization of all of these has led to improved values of Jsc. For devices of approximately 1 cm2 in area, the largest Jsc achieved to date is 28.1 mA/aq cm (AM1.5, SERI/NASA direct normal spectrum, 25 C, total area, 100 mW/sq cm). For this particular cell, the equivalent AM0 value of Jsc was 34.6 mA/sq cm, which appears to be the largest reported for any InP-based cell.

  18. In-Space Propulsion, Logistics Reduction, and Evaluation of Steam Reformer Kinetics: Problems and Prospects

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.; Palaszewski, B. A.; Kulis, M. J.; Gokoglu, S. A.

    2015-01-01

    Human space missions generate waste materials. A 70-kg crewmember creates a waste stream of 1 kg per day, and a four-person crew on a deep space habitat for a 400+ day mission would create over 1600 kg of waste. Converted into methane, the carbon could be used as a fuel for propulsion or power. The NASA Advanced Exploration Systems (AES) Logistics Reduction and Repurposing (LRR) project is investing in space resource utilization with an emphasis on repurposing logistics materials for useful purposes and has selected steam reforming among many different competitive processes as the preferred method for repurposing organic waste into methane. Already demonstrated at the relevant processing rate of 5.4 kg of waste per day, high temperature oxygenated steam consumes waste and produces carbon dioxide, carbon monoxide, and hydrogen which can then be converted into methane catalytically. However, the steam reforming process has not been studied in microgravity. Data are critically needed to understand the mechanisms that allow use of steam reforming in a reduced gravity environment. This paper reviews the relevant literature, identifies gravity-dependent mechanisms within the steam gasification process, and describes an innovative experiment to acquire the crucial kinetic information in a small-scale reactor specifically designed to operate within the requirements of a reduced gravity aircraft flight. The experiment will determine if the steam reformer process is mass-transport limited, and if so, what level of forced convection will be needed to obtain performance comparable to that in 1-g.

  19. Reduction and Analysis of GALFACTS Data in Search of Compact Variable Sources

    NASA Astrophysics Data System (ADS)

    Wenger, Trey; Barenfeld, S.; Ghosh, T.; Salter, C.

    2012-01-01

    The Galactic ALFA Continuum Transit Survey (GALFACTS) is an all-Arecibo sky, full-Stokes survey from 1225 to 1525 MHz using the multibeam Arecibo L-band Feed Array (ALFA). Using data from survey field N1, the first field covered by GALFACTS, we are searching for compact sources that vary in intensity and/or polarization. The multistep procedure for reducing the data includes radio frequency interference (RFI) removal, source detection, Gaussian fitting in multiple dimensions, polarization leakage calibration, and gain calibration. We have developed code to analyze and calculate the calibration parameters from the N1 calibration sources, and apply these to the data of the main run. For detected compact sources, our goal is to compare results from multiple passes over a source to search for rapid variability, as well as to compare our flux densities with those from the NRAO VLA Sky Survey (NVSS) to search for longer time-scale variations.

  20. A search for experiments to exploit the space shuttle environment, volume 1

    NASA Technical Reports Server (NTRS)

    Fenn, J. B.

    1979-01-01

    A search for worthwhile experiments in pure and applied physics and chemistry which might take advantage of conditions achievable aboard the space shuttle is documented. Of particular interest were the very large pumping speeds at high or ultra high vacuum, the highly nonequilibrium composition of the ambient atmosphere, and the relative absence of gravitational effects. Ideas and suggestions were solicated in the course of visits to 31 research establishments in Western Europe, India, and Japan; conversations with over 90 scientists; and presentations at 3 international meetings. Intriguing possibilities emerged in the following arenas: (1) spectroscopy of the transition state in chemical reactions; (2) flame structure and analysis; (3) solid propellant combustion; (4) analysis of atmospheric composition; (5) turbulence effects on aerosol coagulation.

  1. Development and evaluation of a biomedical search engine using a predicate-based vector space model.

    PubMed

    Kwak, Myungjae; Leroy, Gondy; Martinez, Jesse D; Harwell, Jeffrey

    2013-10-01

    Although biomedical information available in articles and patents is increasing exponentially, we continue to rely on the same information retrieval methods and use very few keywords to search millions of documents. We are developing a fundamentally different approach for finding much more precise and complete information with a single query using predicates instead of keywords for both query and document representation. Predicates are triples that are more complex datastructures than keywords and contain more structured information. To make optimal use of them, we developed a new predicate-based vector space model and query-document similarity function with adjusted tf-idf and boost function. Using a test bed of 107,367 PubMed abstracts, we evaluated the first essential function: retrieving information. Cancer researchers provided 20 realistic queries, for which the top 15 abstracts were retrieved using a predicate-based (new) and keyword-based (baseline) approach. Each abstract was evaluated, double-blind, by cancer researchers on a 0-5 point scale to calculate precision (0 versus higher) and relevance (0-5 score). Precision was significantly higher (p<.001) for the predicate-based (80%) than for the keyword-based (71%) approach. Relevance was almost doubled with the predicate-based approach-2.1 versus 1.6 without rank order adjustment (p<.001) and 1.34 versus 0.98 with rank order adjustment (p<.001) for predicate--versus keyword-based approach respectively. Predicates can support more precise searching than keywords, laying the foundation for rich and sophisticated information search. PMID:23892296

  2. Mitigating local minima in full-waveform inversion by expanding the search space

    NASA Astrophysics Data System (ADS)

    van Leeuwen, Tristan; Herrmann, Felix J.

    2013-10-01

    Wave equation based inversions, such as full-waveform inversion and reverse-time migration, are challenging because of their computational costs, memory requirements and reliance on accurate initial models. To confront these issues, we propose a novel formulation of wave equation based inversion based on a penalty method. In this formulation, the objective function consists of a data-misfit term and a penalty term, which measures how accurately the wavefields satisfy the wave equation. This new approach is a major departure from current formulations where forward and adjoint wavefields, which both satisfy the wave equation, are correlated to compute updates for the unknown model parameters. Instead, we carry out the inversions over two alternating steps during which we first estimate the wavefield everywhere, given the current model parameters, source and observed data, followed by a second step during which we update the model parameters, given the estimate for the wavefield everywhere and the source. Because the inversion involves both the synthetic wavefields and the medium parameters, its search space is enlarged so that it suffers less from local minima. Compared to other formulations that extend the search space of wave equation based inversion, our method differs in several aspects, namely (i) it avoids storage and updates of the synthetic wavefields because we calculate these explicitly by finding solutions that obey the wave equation and fit the observed data and (ii) no adjoint wavefields are required to update the model, instead our updates are calculated from these solutions directly, which leads to significant computational savings. We demonstrate the validity of our approach by carefully selected examples and discuss possible extensions and future research.

  3. Medical Response, Search and Recovery during the Space Shuttle Columbia Accident Investigation

    NASA Technical Reports Server (NTRS)

    Stepaniak, Philip C.

    2010-01-01

    On February 1, 2003, the Space Shuttle Columbia broke apart during atmospheric re-entry on mission STS-107. After an event such as this, with high visibility and international interest, the operational challenge of recovering the crewmembers could not be underestimated. The Space Shuttle Program is organized to respond to a vehicle mishap using the resources of the Mishap Investigation Team (MIT). On the afternoon of Feb. 1, 2003, the MIT deployed to Barksdale Air Force Base (AFB), Louisiana. This location became the investigative center and interim storage location for crewmembers received from the Lufkin, Texas Disaster Field Office (DFO). The Lufkin DFO served as the primary area for all operations, including staging assets and deploying field teams for search, recovery and security of crewmember remains. More than 2,000 people from numerous organizations were involved with the recovery of the crew. All seven crewmembers of STS-107 were recovered and ceremonial last rights were administered. Astronaut and military personnel escorted the crew with honor to the MIT at Barksdale AFB, Louisiana. At Barksdale AFB a temporary morgue was established in an aircraft hangar and operated for approximately two weeks during which time coordination with the DFO field recovery teams, Armed Forces Institute of Pathology (AFIP) medical personnel, and the crew surgeons was on going. Families of crewmembers and NASA management were notified daily of the current findings. Working under the leadership of the MIT Lead, the medical team developed and executed a short-term plan to identify and relocate the crew with a military honor guard and protocol to the medical examiner at the Armed Forces Port Mortuary, Dover AFB, Delaware. After operations at Barksdale AFB were concluded the medical team transitioned back to Houston and a long-term plan was developed and implemented which involved the Air Force Mortuary Affairs at Randolph AFB, Texas. This plan was coordinated with search teams

  4. Search for spin-orbit-force reduction at {sup 106,108}Zr around r-process path

    SciTech Connect

    Sumikama, T.; Yoshinaga, K.; Watanabe, H.; and others

    2012-11-12

    Shell gap at the magic number N= 82 is important to reproduce the 2nd peak of r-process abundance. If a spin-orbit force is reduced in a very neutron-rich region, a shell quenching at N= 82 and a new shell closure at N70 are predicted. A shell evolution by the spin-orbit-force reduction can be searched for through the shape evolution of Zr isotopes around an expected double magic nuclei, {sup 110}Zr(Z = 40,N = 70). We performed {beta}-{gamma} and isomer spectroscopy at RIBF to observe low-lying states in {sup 106,108}Zr. The present results indicate a well deformed shape for {sup 106,108}Zr. The drastic reduction of the spin-orbit force most likely does not occur around {sup 110}Zr on an r-process path.

  5. A Hybrid Optimization Framework with POD-based Order Reduction and Design-Space Evolution Scheme

    NASA Astrophysics Data System (ADS)

    Ghoman, Satyajit S.

    The main objective of this research is to develop an innovative multi-fidelity multi-disciplinary design, analysis and optimization suite that integrates certain solution generation codes and newly developed innovative tools to improve the overall optimization process. The research performed herein is divided into two parts: (1) the development of an MDAO framework by integration of variable fidelity physics-based computational codes, and (2) enhancements to such a framework by incorporating innovative features extending its robustness. The first part of this dissertation describes the development of a conceptual Multi-Fidelity Multi-Strategy and Multi-Disciplinary Design Optimization Environment (M3 DOE), in context of aircraft wing optimization. M 3 DOE provides the user a capability to optimize configurations with a choice of (i) the level of fidelity desired, (ii) the use of a single-step or multi-step optimization strategy, and (iii) combination of a series of structural and aerodynamic analyses. The modularity of M3 DOE allows it to be a part of other inclusive optimization frameworks. The M 3 DOE is demonstrated within the context of shape and sizing optimization of the wing of a Generic Business Jet aircraft. Two different optimization objectives, viz. dry weight minimization, and cruise range maximization are studied by conducting one low-fidelity and two high-fidelity optimization runs to demonstrate the application scope of M3 DOE. The second part of this dissertation describes the development of an innovative hybrid optimization framework that extends the robustness of M 3 DOE by employing a proper orthogonal decomposition-based design-space order reduction scheme combined with the evolutionary algorithm technique. The POD method of extracting dominant modes from an ensemble of candidate configurations is used for the design-space order reduction. The snapshot of candidate population is updated iteratively using evolutionary algorithm technique of

  6. Searching the Sequence Space for Potent Aptamers Using SELEX in Silico.

    PubMed

    Zhou, Qingtong; Xia, Xiaole; Luo, Zhaofeng; Liang, Haojun; Shakhnovich, Eugene

    2015-12-01

    To isolate functional nucleic acids that bind to defined targets with high affinity and specificity, which are known as aptamers, the systematic evolution of ligands by exponential enrichment (SELEX) methodology has emerged as the preferred approach. Here, we propose a computational approach, SELEX in silico, that allows the sequence space to be more thoroughly explored regarding binding of a certain target. Our approach consists of two steps: (i) secondary structure-based sequence screening, which aims to collect the sequences that can form a desired RNA motif as an enhanced initial library, followed by (ii) sequence enrichment regarding target binding by molecular dynamics simulation-based virtual screening. Our SELEX in silico method provided a practical computational solution to three key problems in aptamer sequence searching: design of nucleic acid libraries, knowledge of sequence enrichment, and identification of potent aptamers. Six potent theophylline-binding aptamers, which were isolated by SELEX in silico from a sequence space containing 4(13) sequences, were experimentally verified to bind theophylline with high affinity: Kd ranging from 0.16 to 0.52 μM, compared with the dissociation constant of the original aptamer-theophylline, 0.32 μM. These results demonstrate the significant potential of SELEX in silico as a new method for aptamer discovery and optimization. PMID:26642994

  7. Hubble Space Telescope Snapshot Search for Planetary Nebulae in Globular Clusters of the Local Group

    NASA Astrophysics Data System (ADS)

    Bond, Howard E.

    2015-04-01

    Single stars in ancient globular clusters (GCs) are believed incapable of producing planetary nebulae (PNs), because their post-asymptotic-giant-branch evolutionary timescales are slower than the dissipation timescales for PNs. Nevertheless, four PNs are known in Galactic GCs. Their existence likely requires more exotic evolutionary channels, including stellar mergers and common-envelope binary interactions. I carried out a snapshot imaging search with the Hubble Space Telescope (HST) for PNs in bright Local Group GCs outside the Milky Way. I used a filter covering the 5007 Å nebular emission line of [O iii], and another one in the nearby continuum, to image 66 GCs. Inclusion of archival HST frames brought the total number of extragalactic GCs imaged at 5007 Å to 75, whose total luminosity slightly exceeds that of the entire Galactic GC system. I found no convincing PNs in these clusters, aside from one PN in a young M31 cluster misclassified as a GC, and two PNs at such large angular separations from an M31 GC that membership is doubtful. In a ground-based spectroscopic survey of 274 old GCs in M31, Jacoby et al. found three candidate PNs. My HST images of one of them suggest that the [O iii] emission actually arises from ambient interstellar medium rather than a PN; for the other two candidates, there are broadband archival UV HST images that show bright, blue point sources that are probably the PNs. In a literature search, I also identified five further PN candidates lying near old GCs in M31, for which follow-up observations are necessary to confirm their membership. The rates of incidence of PNs are similar, and small but nonzero, throughout the GCs of the Local Group. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, and from the data archive at STScI, which are operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  8. Smart LED lighting for major reductions in power and energy use for plant lighting in space

    NASA Astrophysics Data System (ADS)

    Poulet, Lucie

    optimizing conditions with red and blue LED lighting required 12 times less energy than with a traditional high-intensity discharge lighting system. This study paves the way for refinement of the smart lighting system and further, major reductions in ESM for space life-support systems and for ground-based controlled-environment agriculture. Project supported by NASA grant number NNX09AL99G.

  9. Multi scale Disaster Risk Reduction Systems Space and Community based Experiences over HKH Region

    NASA Astrophysics Data System (ADS)

    Gurung, D. R.; Shrestha, M.; Shrestha, N.; Debnath, B.; Jishi, G.; Bajracharya, R.; Dhonju, H. K.; Pradhan, S.

    2014-11-01

    An increasing trend in the recurrence of natural disasters and associated impacts due to Floods, Glacier Lake out bursts, landslides and forest fire is reported over Hindu Kush Himalyan (HKH) region. Climate change and anthropogenic coupled factors are identified as primary factors for such increased vulnerability. The large degree of poverty, lack of infrastructure, poor accessibility and uncertainties involved in understanding high altitude land surface and climate dynamics poses serious challenges in reducing disaster vulnerability and mitigating disaster impacts. In this context effective development of Disaster Risk Reduction (DRR) protocols and mechanisms have been realized as an urgent need. The paper presents the adoption and experiences of multi scale DRR systems across different Himalayan member countries ranging from community based indigenous early warning to space based emergency response and decision support systems. The Establishment of a Regional Flood Information System (HKH-HYCOS) over Ganges-Brahmaputra-Meghna (GBM) and Indus river basins promoted the timely exchange of flood data and information for the reduction of flood vulnerability within and among the participating countries. Satellite based forest fire alert systems evoked significant response among diverse stakeholders to optimize fire incidence and control. Satellite rainfall estimation products, satellite altimetry based flood early warning systems, flood inundation modelling and products, model derived hydrology flow products from different global data-sharing networks constitutes diverse information to support multi scale DRR systems. Community-based Flood Early Warning System (FEWS) enabled by wireless technology established over the Singara and Jiadhal rivers in Assam also stands as one of the promising examples of minimizing flood risk. Disaster database and information system and decision support tools in Nepal serves as potential tool to support diverse stakeholders.

  10. Space-related pharma-motifs for fast search of protein binding motifs and polypharmacological targets

    PubMed Central

    2012-01-01

    Background To discover a compound inhibiting multiple proteins (i.e. polypharmacological targets) is a new paradigm for the complex diseases (e.g. cancers and diabetes). In general, the polypharmacological proteins often share similar local binding environments and motifs. As the exponential growth of the number of protein structures, to find the similar structural binding motifs (pharma-motifs) is an emergency task for drug discovery (e.g. side effects and new uses for old drugs) and protein functions. Results We have developed a Space-Related Pharmamotifs (called SRPmotif) method to recognize the binding motifs by searching against protein structure database. SRPmotif is able to recognize conserved binding environments containing spatially discontinuous pharma-motifs which are often short conserved peptides with specific physico-chemical properties for protein functions. Among 356 pharma-motifs, 56.5% interacting residues are highly conserved. Experimental results indicate that 81.1% and 92.7% polypharmacological targets of each protein-ligand complex are annotated with same biological process (BP) and molecular function (MF) terms, respectively, based on Gene Ontology (GO). Our experimental results show that the identified pharma-motifs often consist of key residues in functional (active) sites and play the key roles for protein functions. The SRPmotif is available at http://gemdock.life.nctu.edu.tw/SRP/. Conclusions SRPmotif is able to identify similar pharma-interfaces and pharma-motifs sharing similar binding environments for polypharmacological targets by rapidly searching against the protein structure database. Pharma-motifs describe the conservations of binding environments for drug discovery and protein functions. Additionally, these pharma-motifs provide the clues for discovering new sequence-based motifs to predict protein functions from protein sequence databases. We believe that SRPmotif is useful for elucidating protein functions and drug discovery

  11. Update on Risk Reduction Activities for a Liquid Advanced Booster for NASA's Space Launch System

    NASA Technical Reports Server (NTRS)

    Crocker, Andrew M.; Doering, Kimberly B; Meadows, Robert G.; Lariviere, Brian W.; Graham, Jerry B.

    2015-01-01

    The stated goals of NASA's Research Announcement for the Space Launch System (SLS) Advanced Booster Engineering Demonstration and/or Risk Reduction (ABEDRR) are to reduce risks leading to an affordable Advanced Booster that meets the evolved capabilities of SLS; and enable competition by mitigating targeted Advanced Booster risks to enhance SLS affordability. Dynetics, Inc. and Aerojet Rocketdyne (AR) formed a team to offer a wide-ranging set of risk reduction activities and full-scale, system-level demonstrations that support NASA's ABEDRR goals. For NASA's SLS ABEDRR procurement, Dynetics and AR formed a team to offer a series of full-scale risk mitigation hardware demonstrations for an affordable booster approach that meets the evolved capabilities of the SLS. To establish a basis for the risk reduction activities, the Dynetics Team developed a booster design that takes advantage of the flight-proven Apollo-Saturn F-1. Using NASA's vehicle assumptions for the SLS Block 2, a two-engine, F-1-based booster design delivers 150 mT (331 klbm) payload to LEO, 20 mT (44 klbm) above NASA's requirements. This enables a low-cost, robust approach to structural design. During the ABEDRR effort, the Dynetics Team has modified proven Apollo-Saturn components and subsystems to improve affordability and reliability (e.g., reduce parts counts, touch labor, or use lower cost manufacturing processes and materials). The team has built hardware to validate production costs and completed tests to demonstrate it can meet performance requirements. State-of-the-art manufacturing and processing techniques have been applied to the heritage F-1, resulting in a low recurring cost engine while retaining the benefits of Apollo-era experience. NASA test facilities have been used to perform low-cost risk-reduction engine testing. In early 2014, NASA and the Dynetics Team agreed to move additional large liquid oxygen/kerosene engine work under Dynetics' ABEDRR contract. Also led by AR, the

  12. An Overview of Latest Model Reduction and Control Methods of Large Flexible Space Structures

    NASA Technical Reports Server (NTRS)

    Santiago, J. M.; Lange, W. J., Jr.; Jamshidi, M.

    1985-01-01

    The latest trends and theoretical developments involved with the modeling and control of Large Flexible Space Structures (LFSS) are described. The paper addresses first the basic problems, characteristics, and difficulties inherent in modeling and control of LFSS. Major sources of difficulties and errors are the stiffness and damping operators of the dynamic model. Extensions of Linear Quadratic Gaussian (LQG) theory as applied to LFSS are presented, including frequency-shaped cost functionals and perturbation methods. The minimum data/maximum entropy approach which uses a stochastic design model to overcome difficulties found in the LQG-based methods is described. Latest trends in system theory including balanced realization and singular-value analysis are used to determine reduced order controllers and models. Ad hoc methods such as component cost analysis and modal cost analysis are discussed in context with the closed-loop reduction problem of controller order versus performance. The minimum data/maximum entropy approach also addresses controller order versus performance. Those areas of control science and large scale systems that appear to have an important role in understanding and solving LFSS modeling and control are also identified.

  13. Template-space metric for searches for gravitational waves from the inspiral, merger, and ringdown of binary black holes

    NASA Astrophysics Data System (ADS)

    Kalaghatgi, Chinmay; Ajith, Parameswaran; Arun, K. G.

    2015-06-01

    Searches for gravitational waves (GWs) from binary black holes using interferometric GW detectors require the construction of template banks for performing matched filtering while analyzing the data. Placement of templates over the parameter space of binaries, as well as coincidence tests of GW triggers from multiple detectors make use of the definition of a metric over the space of gravitational waveforms. Although recent searches have employed waveform templates coherently describing the inspiral, merger and ringdown (IMR) of the coalescence, the metric used in the template banks and coincidence tests was derived from post-Newtonian inspiral waveforms. In this paper, we compute (semianalytically) the template-space metric of the IMR waveform family IMRPhenomB over the parameter space of masses and the effective spin parameter. We also propose a coordinate system, which is a modified version of post-Newtonian chirp time coordinates, in which the metric is slowly varying over the parameter space. The match function semianalytically computed using the metric has excellent agreement with the "exact" match function computed numerically. We show that the metric is able to provide a reasonable approximation to the match function of other IMR waveform families, such that the effective-one-body model calibrated to numerical relativity (EOBNRv2). The availability of this metric can contribute to improving the sensitivity of searches for GWs from binary black holes in the advanced detector era.

  14. A procedure of multiple period searching in unequally spaced time-series with the Lomb-Scargle method

    NASA Technical Reports Server (NTRS)

    Van Dongen, H. P.; Olofsen, E.; VanHartevelt, J. H.; Kruyt, E. W.; Dinges, D. F. (Principal Investigator)

    1999-01-01

    Periodogram analysis of unequally spaced time-series, as part of many biological rhythm investigations, is complicated. The mathematical framework is scattered over the literature, and the interpretation of results is often debatable. In this paper, we show that the Lomb-Scargle method is the appropriate tool for periodogram analysis of unequally spaced data. A unique procedure of multiple period searching is derived, facilitating the assessment of the various rhythms that may be present in a time-series. All relevant mathematical and statistical aspects are considered in detail, and much attention is given to the correct interpretation of results. The use of the procedure is illustrated by examples, and problems that may be encountered are discussed. It is argued that, when following the procedure of multiple period searching, we can even benefit from the unequal spacing of a time-series in biological rhythm research.

  15. Unique Search and Track Procedures Utilizing the Ground-based Electro-Optical Deep Space Surveillance (GEODSS) Worldwide Sites

    NASA Astrophysics Data System (ADS)

    Bruck, R.; Peppard, T.

    2012-09-01

    The GEODSS Vela Search Team, in conjunction with the Air Force, developed revolutionary new procedures to search for man-made objects in deep space. In the first-ever aggressive, proactive campaign against a series of lost satellites, three GEODSS optical detachments were employed to find Vela communication satellites launched in the 1960s. These satellites, in highly eccentric orbits, had not been tracked in over 40 years. The Team exploited GEODSS telescopes and technology for a mission they were not designed to perform by employing modified optical viewing parameters and new search techniques. Using the sun to provide illumination, while modifying optical parameters, the GEODSS team found 5 lost Vela satellites and enhanced the Air Force Space Command satellite catalog. In addition, the Team developed two new tactics, techniques & procedures to capture very hard-to-track objects. Revisit time was increased from intermittent and yearly tracking to weeks or better to find 3 Velas lost for over four decades. The Joint Space Operations Center (JSPOC) analysts stated that the Vela search and tracking was a great success. Additionally, a GEODSS Tactics Development Team was the first to use a deep space observing telescope to track satellites in near earth orbits and outside of the traditional observing period. The team was able to observe and provide metric track data on the International Space Station, Hubble Space Telescope and several other satellites in Near Earth Orbits. Additionally, data was collected before the civil sunset observing period on the Phobos-Grunt re-entry and an Iridium Communications Satellite in Low Earth Orbit. The ability to observe and then successfully repeat the process was an astronomical achievement. The GEODSS team accomplishments pushed the boundaries of the GEODSS system design and proved existing capabilities that had not yet been considered. Lessons learned were established for Vela & other orbit types.

  16. The millimeter wave spectrum of methyl cyanate: a laboratory study and astronomical search in space

    NASA Astrophysics Data System (ADS)

    Kolesniková, L.; Alonso, J. L.; Bermúdez, C.; Alonso, E. R.; Tercero, B.; Cernicharo, J.; Guillemin, J.-C.

    2016-06-01

    Aims: The recent discovery of methyl isocyanate (CH3NCO) in Sgr B2(N) and Orion KL makes methyl cyanate (CH3OCN) a potential molecule in the interstellar medium. The aim of this work is to fulfill the first requirement for its unequivocal identification in space, i.e. the availability of transition frequencies with high accuracy. Methods: The room-temperature rotational spectrum of methyl cyanate was recorded in the millimeter wave domain from 130 to 350 GHz. All rotational transitions revealed A-E splitting owing to methyl internal rotation and were globally analyzed using the ERHAM program. Results: The data set for the ground torsional state of methyl cyanate exceeds 700 transitions within J'' = 10-35 and K"a= 0-13 and newly derived spectroscopic constants reproduce the spectrum close to the experimental uncertainty. Spectral features of methyl cyanate were then searched for in Orion KL, Sgr B2(N), B1-b, and TMC-1 molecular clouds. Upper limits to the column density of methyl cyanate are provided. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00009.SV. Tables 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A75

  17. Reducing a Knowledge-Base Search Space When Data Are Missing

    NASA Technical Reports Server (NTRS)

    James, Mark

    2007-01-01

    This software addresses the problem of how to efficiently execute a knowledge base in the presence of missing data. Computationally, this is an exponentially expensive operation that without heuristics generates a search space of 1 + 2n possible scenarios, where n is the number of rules in the knowledge base. Even for a knowledge base of the most modest size, say 16 rules, it would produce 65,537 possible scenarios. The purpose of this software is to reduce the complexity of this operation to a more manageable size. The problem that this system solves is to develop an automated approach that can reason in the presence of missing data. This is a meta-reasoning capability that repeatedly calls a diagnostic engine/model to provide prognoses and prognosis tracking. In the big picture, the scenario generator takes as its input the current state of a system, including probabilistic information from Data Forecasting. Using model-based reasoning techniques, it returns an ordered list of fault scenarios that could be generated from the current state, i.e., the plausible future failure modes of the system as it presently stands. The scenario generator models a Potential Fault Scenario (PFS) as a black box, the input of which is a set of states tagged with priorities and the output of which is one or more potential fault scenarios tagged by a confidence factor. The results from the system are used by a model-based diagnostician to predict the future health of the monitored system.

  18. Searching the Future for the Legal Regime of Space Activities: the Need for Unification of National Space Legislation' Provisions

    NASA Astrophysics Data System (ADS)

    Negoda, S. A.

    2002-01-01

    space activities. For the future legal regime of space activities it is vital to preserve the existed principles and main provisions of the international space law. related legislations are developing rapidly. They become serious instrument for legal regulation of space activities. those projects with a foreign party involvement. Quite often partners in international space projects agree to choice a domestic law of one of them. They do this for defining a certain organizational and/or contractual issue (disputes settlement, for example) of the project. that such practice will spread widely. could help to preserve the existed important provisions of international space law (responsibility of states for their national activities, for instance). development of international space private law. We believe that solely special laws and regulations of national legislations could not regulate modern space activities. Being more and more commercial, space activities are becoming a real part of "downed to Earth" commercial activities. Therefore, in many countries provisions of civil, commercial, investment and other branches of national law are applied to such activities. which could low possible risks of such activities and to control them. Such unification seems to be suitable in the following fields: 1)implementation of provisions of international space law in national space laws; 2)definition of unified terminology, accepted by national laws of all parties; 3)unification in national legislations of a certain standards (insurance rates and rules, for instance); 4)unification in national laws of issues related to liability (for instance, a mutual wave of liability in certain types of 5)implementation in national laws of unified rules and procedures of space-related commercial disputes settlement; 6)unification of mechanisms for protection of space-related intellectual property. unification of their provisions. Special attention is paid to provisions of private law

  19. Reduction of space charge breakdown in e-beam irradiated nano/polymethyl methacrylate composites

    SciTech Connect

    Zheng Feihu; Zhang Yewen; An Zhenlian; Dong Jianxing; Lei Qingquan

    2013-01-07

    Fast discharge of numerous space charges in dielectric materials can cause space charge breakdown. This letter reports the role of nanoparticles in affecting space charge breakdown of nano/polymethyl methacrylate composites. Space charge distributions in the composites, implanted by electron beam irradiation, were measured by pressure wave propagation method. The results show that the nanoparticles have significant effects on the isothermal charge decay and space charge breakdown in the nanocomposites. The resistance to space charge breakdown in the nanocomposites is attributed to the combined action of the introduction of deep trapping states and the scattering effect by the added nanoparticles.

  20. A DFT-based genetic algorithm search for AuCu nanoalloy electrocatalysts for CO₂ reduction.

    PubMed

    Lysgaard, Steen; Mýrdal, Jón S G; Hansen, Heine A; Vegge, Tejs

    2015-11-14

    Using a DFT-based genetic algorithm (GA) approach, we have determined the most stable structure and stoichiometry of a 309-atom icosahedral AuCu nanoalloy, for potential use as an electrocatalyst for CO2 reduction. The identified core-shell nano-particle consists of a copper core interspersed with gold atoms having only copper neighbors and a gold surface with a few copper atoms in the terraces. We also present an adsorbate-dependent correction scheme, which enables an accurate determination of adsorption energies using a computationally fast, localized LCAO-basis set. These show that it is possible to use the LCAO mode to obtain a realistic estimate of the molecular chemisorption energy for systems where the computation in normal grid mode is not computationally feasible. These corrections are employed when calculating adsorption energies on the Cu, Au and most stable mixed particles. This shows that the mixed Cu135@Au174 core-shell nanoalloy has a similar adsorption energy, for the most favorable site, as a pure gold nano-particle. Cu, however, has the effect of stabilizing the icosahedral structure because Au particles are easily distorted when adding adsorbates. PMID:25924775

  1. HUBBLE SPACE TELESCOPE NARROWBAND SEARCH FOR EXTENDED Ly{alpha} EMISSION AROUND TWO z > 6 QUASARS

    SciTech Connect

    Decarli, Roberto; Walter, Fabian; Yang Yujin; Hennawi, Joseph F.; Rix, Hans-Walter; Venemans, Bram P.; Carilli, Chris L.; Fan Xiahoui; Kurk, Jaron; Riechers, Dominik; Strauss, Michael A.

    2012-09-10

    We search for extended Ly{alpha} emission around two z > 6 quasars, SDSS J1030+0524 (z = 6.309) and SDSS J1148+5251 (z = 6.419) using Wide Field Camera 3 narrowband filters on board the Hubble Space Telescope. For each quasar, we collected two deep, narrowband images, one sampling the Ly{alpha} line+continuum at the quasar redshifts and one of the continuum emission redward of the line. After carefully modeling the point-spread function, we find no evidence for extended Ly{alpha} emission. These observations set 2{sigma} limits of L(Ly{alpha}, extended) <3.2 Multiplication-Sign 10{sup 44} erg s{sup -1} for J1030+0524 and L(Ly{alpha}, extended) <2.5 Multiplication-Sign 10{sup 44} erg s{sup -1} for J1148+5251. Given the star formation rates typically inferred from (rest-frame) far-infrared measurements of z {approx} 6 quasars, these limits are well below the intrinsic bright Ly{alpha} emission expected from the recombination of gas photoionized by the quasars or by the star formation in the host galaxies, and point toward significant Ly{alpha} suppression or dust attenuation. However, small extinction values have been observed along the line of sight to the nuclei, thus reddening has to be coupled with other mechanisms for Ly{alpha} suppression (e.g., resonance scattering). No Ly{alpha} emitting companions are found, down to a 5{sigma} sensitivity of {approx}1 Multiplication-Sign 10{sup -17} erg s{sup -1} cm{sup -2} arcsec{sup -2} (surface brightness) and {approx}5 Multiplication-Sign 10{sup -17} erg s{sup -1} cm{sup -2} (assuming point sources).

  2. Optimal search strategies of space-time coupled random walkers with finite lifetimes.

    PubMed

    Campos, D; Abad, E; Méndez, V; Yuste, S B; Lindenberg, K

    2015-05-01

    We present a simple paradigm for detection of an immobile target by a space-time coupled random walker with a finite lifetime. The motion of the walker is characterized by linear displacements at a fixed speed and exponentially distributed duration, interrupted by random changes in the direction of motion and resumption of motion in the new direction with the same speed. We call these walkers "mortal creepers." A mortal creeper may die at any time during its motion according to an exponential decay law characterized by a finite mean death rate ω(m). While still alive, the creeper has a finite mean frequency ω of change of the direction of motion. In particular, we consider the efficiency of the target search process, characterized by the probability that the creeper will eventually detect the target. Analytic results confirmed by numerical results show that there is an ω(m)-dependent optimal frequency ω=ω(opt) that maximizes the probability of eventual target detection. We work primarily in one-dimensional (d=1) domains and examine the role of initial conditions and of finite domain sizes. Numerical results in d=2 domains confirm the existence of an optimal frequency of change of direction, thereby suggesting that the observed effects are robust to changes in dimensionality. In the d=1 case, explicit expressions for the probability of target detection in the long time limit are given. In the case of an infinite domain, we compute the detection probability for arbitrary times and study its early- and late-time behavior. We further consider the survival probability of the target in the presence of many independent creepers beginning their motion at the same location and at the same time. We also consider a version of the standard "target problem" in which many creepers start at random locations at the same time. PMID:26066127

  3. Optimal search strategies of space-time coupled random walkers with finite lifetimes

    NASA Astrophysics Data System (ADS)

    Campos, D.; Abad, E.; Méndez, V.; Yuste, S. B.; Lindenberg, K.

    2015-05-01

    We present a simple paradigm for detection of an immobile target by a space-time coupled random walker with a finite lifetime. The motion of the walker is characterized by linear displacements at a fixed speed and exponentially distributed duration, interrupted by random changes in the direction of motion and resumption of motion in the new direction with the same speed. We call these walkers "mortal creepers." A mortal creeper may die at any time during its motion according to an exponential decay law characterized by a finite mean death rate ωm. While still alive, the creeper has a finite mean frequency ω of change of the direction of motion. In particular, we consider the efficiency of the target search process, characterized by the probability that the creeper will eventually detect the target. Analytic results confirmed by numerical results show that there is an ωm-dependent optimal frequency ω =ωopt that maximizes the probability of eventual target detection. We work primarily in one-dimensional (d =1 ) domains and examine the role of initial conditions and of finite domain sizes. Numerical results in d =2 domains confirm the existence of an optimal frequency of change of direction, thereby suggesting that the observed effects are robust to changes in dimensionality. In the d =1 case, explicit expressions for the probability of target detection in the long time limit are given. In the case of an infinite domain, we compute the detection probability for arbitrary times and study its early- and late-time behavior. We further consider the survival probability of the target in the presence of many independent creepers beginning their motion at the same location and at the same time. We also consider a version of the standard "target problem" in which many creepers start at random locations at the same time.

  4. The Attentional Fields of Visual Search in Simultanagnosia and Healthy Individuals: How Object and Space Attention Interact.

    PubMed

    Khan, A Z; Prost-Lefebvre, M; Salemme, R; Blohm, G; Rossetti, Y; Tilikete, C; Pisella, L

    2016-03-01

    Simultanagnosia is a deficit in which patients are unable to perceive multiple objects simultaneously. To date, it remains disputed whether this deficit results from disrupted object or space perception. We asked both healthy participants as well as a patient with simultanagnosia to perform different visual search tasks of variable difficulty. We also modulated the number of objects (target and distracters) presented. For healthy participants, we found that each visual search task was performed with a specific "attentional field" depending on the difficulty of visual object processing but not on the number of objects falling within this "working space." This was demonstrated by measuring the cost in reaction times using different gaze-contingent visible window sizes. We found that bilateral damage to the superior parietal lobule impairs the spatial integration of separable features (within-object processing), shrinking the attentional field in which a target can be detected, but causing no deficit in processing multiple objects per se. PMID:25840422

  5. Assessment of Technology Readiness Level of a Carbon Dioxide Reduction Assembly (CRA) for use on International Space Station

    NASA Technical Reports Server (NTRS)

    Murdoch, Karen; Smith, Fred; Perry, Jay; Green, Steve

    2004-01-01

    When technologies are traded for incorporation into vehicle systems to support a specific mission scenario, they are often assessed in terms of Technology Readiness Level (TRL). TRL is based on three major categories of Core Technology Components, Ancillary Hardware and System Maturity, and Control and Control Integration. This paper describes the Technology Readiness Level assessment of the Carbon Dioxide Reduction Assembly (CRA) for use on the International Space Station. A team comprising of the NASA Johnson Space Center, Marshall Space Flight Center, Southwest Research Institute and Hamilton Sundstrand Space Systems International have been working on various aspects of the CRA to bring its TRL from 4/5 up to 6. This paper describes the work currently being done in the three major categories. Specific details are given on technology development of the Core Technology Components including the reactor, phase separator and CO2 compressor.

  6. State-space reduction and equivalence class sampling for a molecular self-assembly model.

    PubMed

    Packwood, Daniel M; Han, Patrick; Hitosugi, Taro

    2016-07-01

    Direct simulation of a model with a large state space will generate enormous volumes of data, much of which is not relevant to the questions under study. In this paper, we consider a molecular self-assembly model as a typical example of a large state-space model, and present a method for selectively retrieving 'target information' from this model. This method partitions the state space into equivalence classes, as identified by an appropriate equivalence relation. The set of equivalence classes H, which serves as a reduced state space, contains none of the superfluous information of the original model. After construction and characterization of a Markov chain with state space H, the target information is efficiently retrieved via Markov chain Monte Carlo sampling. This approach represents a new breed of simulation techniques which are highly optimized for studying molecular self-assembly and, moreover, serves as a valuable guideline for analysis of other large state-space models. PMID:27493765

  7. State-space reduction and equivalence class sampling for a molecular self-assembly model

    PubMed Central

    Han, Patrick; Hitosugi, Taro

    2016-01-01

    Direct simulation of a model with a large state space will generate enormous volumes of data, much of which is not relevant to the questions under study. In this paper, we consider a molecular self-assembly model as a typical example of a large state-space model, and present a method for selectively retrieving ‘target information’ from this model. This method partitions the state space into equivalence classes, as identified by an appropriate equivalence relation. The set of equivalence classes H, which serves as a reduced state space, contains none of the superfluous information of the original model. After construction and characterization of a Markov chain with state space H, the target information is efficiently retrieved via Markov chain Monte Carlo sampling. This approach represents a new breed of simulation techniques which are highly optimized for studying molecular self-assembly and, moreover, serves as a valuable guideline for analysis of other large state-space models. PMID:27493765

  8. Impact of an elastic sphere with an elastic half space revisited: Numerical analysis based on the method of dimensionality reduction

    PubMed Central

    Lyashenko, I. A.; Popov, V. L.

    2015-01-01

    An impact of an elastic sphere with an elastic half space under no-slip conditions (infinitely large coefficient of friction) is studied numerically using the method of dimensionality reduction. It is shown that the rebound velocity and angular velocity, written as proper dimensionless variables, are determined by a function of only the ratio of tangential and normal stiffness ("Mindlin-ratio"). The obtained numerical results can be approximated by a simple analytical expression. PMID:25684339

  9. Space Launch System NASA Research Announcement Advanced Booster Engineering Demonstration and/or Risk Reduction

    NASA Technical Reports Server (NTRS)

    Crumbly, Christopher M.; Craig, Kellie D.

    2011-01-01

    The intent of the Advanced Booster Engineering Demonstration and/or Risk Reduction (ABEDRR) effort is to: (1) Reduce risks leading to an affordable Advanced Booster that meets the evolved capabilities of SLS (2) Enable competition by mitigating targeted Advanced Booster risks to enhance SLS affordability. Key Concepts (1) Offerors must propose an Advanced Booster concept that meets SLS Program requirements (2) Engineering Demonstration and/or Risk Reduction must relate to the Offeror s Advanced Booster concept (3) NASA Research Announcement (NRA) will not be prescriptive in defining Engineering Demonstration and/or Risk Reduction

  10. Reduction of space-time by a constraint for C(0) metrics

    NASA Astrophysics Data System (ADS)

    Hortaçsu, M.; Özdemir, N.

    1994-01-01

    It is shown how a constraint imposed by the physical relevance of the solutions reduces the dimension of space-time. The C(0) metric given by Nutku is used to describe gravitational shock waves and the trivial case is looked at. It is found that imposing triviality on the solutions reduces the dimension of space-time by one.

  11. Site candidates for ground-based telescope devoted to space debris searching

    NASA Astrophysics Data System (ADS)

    Jiang, Hu; Hu, Haiying; Shen, Xue-min

    2015-12-01

    The demands for space debris scanning have been increasingly urgent in recent decade. The more space activities, the more urgent demands for space debris information. China has laid out space debris scanning from ground-based observation facilities. According to the latitudinal boundaries of China, north latitudes of 20deg, 30deg, 40deg, 50deg, 60deg are considered to be candidates for telescope sites. Space debris distribution is simulated under the assumption that telescopes are stationed in north latitudes of 20deg, 30deg, 40deg, 50deg, 60deg respectively. According to space debris simulations, it is recommended that the telescope dedicated to space debris scanning should be deployed in lower latitudes in order to achieve a better performance in detecting space debrises for China observing users.

  12. Guidelines for contingency planning NASA (National Aeronautics and Space Administration) ADP security risk reduction decision studies

    NASA Technical Reports Server (NTRS)

    Tompkins, F. G.

    1984-01-01

    Guidance is presented to NASA Computer Security Officials for determining the acceptability or unacceptability of ADP security risks based on the technical, operational and economic feasibility of potential safeguards. The risk management process is reviewed as a specialized application of the systems approach to problem solving and information systems analysis and design. Reporting the results of the risk reduction analysis to management is considered. Report formats for the risk reduction study are provided.

  13. Looking at scenes while searching for numbers: Dividing attention multiplies space

    PubMed Central

    Intraub, Helene; Daniels, Karen K.; Horowitz, Todd S.; Wolfe, Jeremy M.

    2015-01-01

    Observers tend to remember seeing a greater expanse of a scene than was shown (boundary extension [BE]). Is undivided visual attention necessary for BE? In Experiment 1, 108 observers viewed photographs with superimposed numerals (2s and 5s). Each appeared for 750 msec, followed by a masked interval and a test picture (same, closer up, or wider angled). Test pictures were rated as the same, closer, or wider angled on a 5-point scale. Visual attention was manipulated with a search task: The observers reported the number of 5s (zero, one, or two). The observers performed search only, picture rating only, or both (giving search priority). Search accuracy was unaffected by condition. BE occurred in both conditions but was greater with divided attention. The results were replicated using incidental BE tests (Experiments 2 and 3). We propose that anticipatory representation of layout occurs automatically during scene perception, with focal attention serving to constrain the boundary error. PMID:18927017

  14. Space-fractional Fokker-Planck equation and optimization of random search processes in the presence of an external bias

    NASA Astrophysics Data System (ADS)

    Palyulin, Vladimir V.; Chechkin, Aleksei V.; Metzler, Ralf

    2014-11-01

    Based on the space-fractional Fokker-Planck equation with a δ-sink term, we study the efficiency of random search processes based on Lévy flights with power-law distributed jump lengths in the presence of an external drift, for instance, an underwater current, an airflow, or simply the preference of the searcher based on prior experience. While Lévy flights turn out to be efficient search processes when the target is upstream relative to the starting point, in the downstream scenario, regular Brownian motion turns out to be advantageous. This is caused by the occurrence of leapovers of Lévy flights, due to which Lévy flights typically overshoot a point or small interval. Studying the solution of the fractional Fokker-Planck equation, we establish criteria when the combination of the external stream and the initial distance between the starting point and the target favours Lévy flights over the regular Brownian search. Contrary to the common belief that Lévy flights with a Lévy index α = 1 (i.e. Cauchy flights) are optimal for sparse targets, we find that the optimal value for α may range in the entire interval (1, 2) and explicitly include Brownian motion as the most efficient search strategy overall.

  15. NASA's New Laser Risk Reduction Program For Future Space Lidar Missions

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Singh, Upendra N.; Heaps, William S.; Cazeau, Tony

    2002-01-01

    NASA has been performing ground, airborne, and space-based scientific measurements since it was formed in 1958. Initial ground and airborne measurements were made with in situ instruments. By necessity, initial earth observation space-based missions were accomplished with passive remote sensing. Active microwave radar was added to the sensor repertoire in the late 1970s. A few key measurements important to NASA remain unaccomplished, however, despite the passive and radar successes. These critical measurements include space-based altimetry; and high spatial resolution profiling of aerosol properties, wind velocity, clouds, and molecular concentrations. Fortunately, a new technology, active optical radar or laser radar or lidar, has matured to the point that the last decade has seen a growing consideration of lidar for space missions. Part of the surge in consideration of lidar has been the tremendous progress in solid-state lasers fueled by advances in crystal growth quality and pump laser diode technology.

  16. NEAT: an astrometric space telescope to search for habitable exoplanets in the solar neighborhood

    NASA Astrophysics Data System (ADS)

    Crouzier, A.; Malbet, F.; Kern, P.; Feautrier, P.; Preiss, O.; Martin, G.; Henault, F.; Stadler, E.; Lafrasse, S.; Behar, E.; Saintpe, M.; Dupont, J.; Potin, S.; Lagage, P.-O.; Cara, C.; Leger, A.; Leduigou, J.-M.; Shao, M.; Goullioud, R.

    2014-03-01

    radial velocities and direct imaging, it will explore in a quasi systematic way the nearby planetary systems. The resulting catalog of planetary systems will be very useful to constrain planetary formation models. The second objective is to find very close Earth analogs. These will be top priority targets for a spectroscopic mission aimed at detecting biomarquers. The current activities related to NEAT revolve around 3 themes: i) a lab demonstration: an optical bench replicates the NEAT optical configuration and metrology system in order to demonstrate the feasibility of measuring centroids with a differential accuracy of 5 µpixels (corresponding to 0.3 micro arc sec on sky) ii) a definition phase study of the NEAT mission done by CNES (the "French Space Agency") iii) an end to end simulation of the NEAT data reduction pipeline: from astrometric and RVs measurements to planets All of these activities are focused on the need to answer the next ESA call for M class missions in 2014 with an improved NEAT concept.

  17. Militarization of space. (Latest citations from the NTIS data base). Published Search

    SciTech Connect

    Not Available

    1992-04-01

    The bibliography contains citations concerning existing and projected military use of space by the United States and foreign powers. Long term strategies, technical feasibility studies, and the use of space in tactical operations are considered. Space weapons, including high-energy lasers, shuttle operations, and the Strategic Defense Initiative (SDI) program are examined. (Contains 250 citations and includes a subject term index and title list.)

  18. OBJECTIVE REDUCTION OF THE SPACE-TIME DOMAIN DIMENSIONALITY FOR EVALUATING MODEL PERFORMANCE

    EPA Science Inventory

    In the United States, photochemical air quality models are the principal tools used by governmental agencies to develop emission reduction strategies aimed at achieving National Ambient Air Quality Standards (NAAQS). Before they can be applied with confidence in a regulatory sett...

  19. Pre-Launch Risk Reduction Activities Conducted at KSC for the International Space Station

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, Paul

    2011-01-01

    In the development of any large scale space-based multi-piece assembly effort, planning must include provisions for testing and verification; not only of the individual pieces but also of the pieces together. Without such testing on the ground, the risk to cost, schedule and technical performance increases substantially. This paper will review the efforts undertaken by the International Space Station (ISS), including the International Partners, during the pre-launch phase, primarily at KSC, to reduce the risks associated with the on-orbit assembly and operation of the ISS.

  20. Space Nuclear Reactor Electric Power. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning studies and conceptual designs of nuclear space power reactors to generate electric power for space missions. The citations cover the technology, safety aspects, and policy considerations. (Contains 250 citations and includes a subject term index and title list.)

  1. 14 CFR 1206.702 - Waiver or reduction of fees.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Waiver or reduction of fees. 1206.702 Section 1206.702 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION AVAILABILITY OF AGENCY RECORDS TO MEMBERS OF THE PUBLIC Search, Review, and Duplication Fees § 1206.702 Waiver...

  2. 14 CFR 1206.702 - Waiver or reduction of fees.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false Waiver or reduction of fees. 1206.702 Section 1206.702 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION AVAILABILITY OF AGENCY RECORDS TO MEMBERS OF THE PUBLIC Search, Review, and Duplication Fees § 1206.702 Waiver...

  3. 14 CFR 1206.702 - Waiver or reduction of fees.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Waiver or reduction of fees. 1206.702 Section 1206.702 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION AVAILABILITY OF AGENCY RECORDS TO MEMBERS OF THE PUBLIC Search, Review, and Duplication Fees § 1206.702 Waiver...

  4. 14 CFR 1206.702 - Waiver or reduction of fees.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Waiver or reduction of fees. 1206.702 Section 1206.702 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION AVAILABILITY OF AGENCY RECORDS TO MEMBERS OF THE PUBLIC Search, Review, and Duplication Fees § 1206.702 Waiver...

  5. Effects of Link Annotations on Search Performance in Layered and Unlayered Hierarchically Organized Information Spaces.

    ERIC Educational Resources Information Center

    Fraser, Landon; Locatis, Craig

    2001-01-01

    Investigated the effects of link annotations on high school user search performance in Web hypertext environments having deep (layered) and shallow link structures. Results confirmed previous research that shallow link structures are better than deep (layered) link structures, and also showed that annotations had virtually no effect on search…

  6. INDOOR RADON REDUCTION IN CRAWL-SPACE HOUSES: A REVIEW OF ALTERNATIVE APPROACHES

    EPA Science Inventory

    An analysis has been completed of the performance, mechanisms, and costs of alternative technologies for preventing radon entry into the living areas of houses having crawl-space foundations. Sub-membrane depressurization (SMD) is consistently the most effective technique, often ...

  7. Properties of heuristic search strategies

    NASA Technical Reports Server (NTRS)

    Vanderbrug, G. J.

    1973-01-01

    A directed graph is used to model the search space of a state space representation with single input operators, an AND/OR is used for problem reduction representations, and a theorem proving graph is used for state space representations with multiple input operators. These three graph models and heuristic strategies for searching them are surveyed. The completeness, admissibility, and optimality properties of search strategies which use the evaluation function f = (1 - omega)g = omega(h) are presented and interpreted using a representation of the search process in the plane. The use of multiple output operators to imply dependent successors, and thus obtain a formalism which includes all three types of representations, is discussed.

  8. Partition search

    SciTech Connect

    Ginsberg, M.L.

    1996-12-31

    We introduce a new form of game search called partition search that incorporates dependency analysis, allowing substantial reductions in the portion of the tree that needs to be expanded. Both theoretical results and experimental data are presented. For the game of bridge, partition search provides approximately as much of an improvement over existing methods as {alpha}-{beta} pruning provides over minimax.

  9. Rebound indentation problem for a viscoelastic half-space and axisymmetric indenter - Solution by the method of dimensionality reduction

    NASA Astrophysics Data System (ADS)

    Argatov, Ivan I.; Popov, Valentin L.

    2016-08-01

    The method of dimensionality reduction (MDR) is extended for the axisymmetric frictionless unilateral Hertz-type contact problem for a viscoelastic half-space and an arbitrary axisymmetric rigid indenter under the assumption that an arbitrarily evolving in time circular contact area remains singly connected during the whole process of indentation. In particular, the MDR is applied to study in detail the so-called rebound indentation problem, where the contact radius has a single maximum. It is shown that the obtained closed-form analytical solution for the rebound indentation displacement (recorded in the recovery phase, when the contact force vanishes) does not depend on the indenter shape.

  10. Crosstalk reduction in free space optical interconnects systems using microlenses with Gaussian transmittance

    NASA Astrophysics Data System (ADS)

    Al-Ababneh, Nedal

    2014-05-01

    A novel method to reduce the diffraction crosstalk for micro-lens based free space optical interconnects is presented. Instead of using microlenses with uniform transmittance apertures, the use of microlenses with non-uniform transmittance apertures is proposed. It is shown that the diffraction crosstalk which exists in the free space interconnects systems that use microlenses with uniform transmittance apertures can be substantially reduced by using microlenses with Gaussian transmittance. The optical field at the detectors array using both the uniform and Gaussian apertures have been derived and used to calculate the crosstalk. Numerical results have been introduced to show the improvement of the signal-to-crosstalk ratio when using the Gaussian transmittance for the microlens.

  11. Reduction of spermatogonia and testosterone in rat testes flown on Space Lab-3

    NASA Technical Reports Server (NTRS)

    Philpott, Delbert E.; Stevenson, J.; Black, S.; Sapp, W.; Williams, C.

    1986-01-01

    The effects of space flight on rat testes were investigated. The weight, spermatogonial cell count, and testosterone levels in six rats flown on Space Lab-3 were measured. It is observed that compared to ground control rats the average weight loss was 7.1 percent and the spermatogonial cell count decreased by 7.5 percent. The data reveal that the testosterone level for large control rats was 9.13 ng/ml and 0.31 ng/ml for flight rats; and 2.54 ng/ml and 0.233 ng/ml for smaller control and flight rats, respectively. It is noted that spermatogenesis and testosterone production are reduced during spaceflight.

  12. Reflected Sunlight Reduction and Characterization for a Deep-Space Optical Receiver Antenna (DSORA)

    NASA Technical Reports Server (NTRS)

    Clymer, B. D.

    1990-01-01

    A baffle system for the elimination of first-order specular and diffuse reflection of sunlight from the sunshade of a deep-space optical receiver telescope is presented. This baffle system consists of rings of 0.5cm blades spaced 2.5 cm apart on the walls of GO hexagonal sunshade tubes that combine to form the telescope sunshade. The shadow cast by the blades, walls, and rims of the tubes prevent all first-order reflections of direct sunlight from reaching the primary mirror of the telescope. A reflection model of the sunshade without baffles is also presented for comparison. Since manufacturers of absorbing surfaces do not measure data near grazing incidence, the reflection properties at anticipated angles of incidence must be characterized. A description of reflection from matte surfaces in term of bidirectional reflection distribution function (BRDF) is presented along with a discussion of measuring BRDF near grazing incidence.

  13. Space Radiation Quality Factors and the Delta Ray Dose and Dose-Rate Reduction Effectiveness Factor.

    PubMed

    Cucinotta, Francis A; Cacao, Eliedonna; Alp, Murat

    2016-03-01

    In this paper, the authors recommend that the dose and dose-rate effectiveness factor used for space radiation risk assessments should be based on a comparison of the biological effects of energetic electrons produced along a cosmic ray particles path in low fluence exposures to high dose-rate gamma-ray exposures of doses of about 1 Gy. Methods to implement this approach are described. PMID:26808878

  14. Cooperative learning over composite search spaces: Experiences with a multi-agent design system

    SciTech Connect

    Prasad, M.V.N.; Lesser, V.R.; Lander, S.E.

    1996-12-31

    We suggest the use of two learning techniques - short term and long term - to enhance search efficiency in a multi-agent design system by letting the agents learn about non-local requirements on the local search process. The first technique allows an agent to accumulate and apply constraining information about global problem solving, gathered as a result of agent communication, to further problem solving within the same problem instance. The second technique is used to classify problem instances and appropriately index and retrieve constraining information to apply to new problem instances. These techniques will be presented within the context of a multi-agent parametric-design application called STEAM. We show that learning conclusively improves solution quality and processing-time results.

  15. Development of a Wake Vortex Spacing System for Airport Capacity Enhancement and Delay Reduction

    NASA Technical Reports Server (NTRS)

    Hinton, David A.; OConnor, Cornelius J.

    2000-01-01

    The Terminal Area Productivity project has developed the technologies required (weather measurement, wake prediction, and wake measurement) to determine the aircraft spacing needed to prevent wake vortex encounters in various weather conditions. The system performs weather measurements, predicts bounds on wake vortex behavior in those conditions, derives safe wake spacing criteria, and validates the wake predictions with wake vortex measurements. System performance to date indicates that the potential runway arrival rate increase with Aircraft VOrtex Spacing System (AVOSS), considering common path effects and ATC delivery variance, is 5% to 12% depending on the ratio of large and heavy aircraft. The concept demonstration system, using early generation algorithms and minimal optimization, is performing the wake predictions with adequate robustness such that only 4 hard exceedances have been observed in 1235 wake validation cases. This performance demonstrates the feasibility of predicting wake behavior bounds with multiple uncertainties present, including the unknown aircraft weight and speed, weather persistence between the wake prediction and the observations, and the location of the weather sensors several kilometers from the approach location. A concept for the use of the AVOSS system for parallel runway operations has been suggested, and an initial study at the JFK International Airport suggests that a simplified AVOSS system can be successfully operated using only a single lidar as both the weather sensor and the wake validation instrument. Such a selfcontained AVOSS would be suitable for wake separation close to the airport, as is required for parallel approach concepts such as SOIA.

  16. Intelligent search and retrieval of a large multimedia knowledgebase for the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Clapis, Paul J.; Byers, William S.

    1990-01-01

    A document-retrieval assistant (DRA) in a microcomputer format is described which incorporates hypertext and natural language capabilities. Hypertext is used to introduce an intelligent search capability, and the natural-language interface permits access to specific data without the use of keywords. The DRA can be used to access and 'browse' the large multimedia database that is composed of project documentation from the HST.

  17. Great SEP events and space weather: 1. Experience of automatically searching for event beginnings; probabilities of false and missed events

    NASA Astrophysics Data System (ADS)

    Applbaum, David; Dorman, Lev; Pustil'Nik, Lev; Sternlieb, Abraham; Zagnetko, Alexander; Zukerman, Igor

    It is well known that during great SEP events, fluxes of energetic particles can be so big that the memory of computers and other electronics in space may be destroyed, and satellites and spacecraft may cease to function. According to the NOAA Space Weather Prediction Cen-ter, the following scales constitute dangerous solar radiation storms: S5-extreme (flux level of particles with energy ∼ 10 MeV more than 105 ); S4 - severe(f luxmorethan104 ); andS3 - strong(f luxmorethan103 ). In these persiods, it is necessary to switch off some of the electronics for a few hours energy particles (meaning those with a few GeV/nucleon and higher), whose transportation to Earthfrom the S20 minutes after they accelerate and escape into the solar wind) than the main bulk of the smaller energy particle 60 minutes later). Here we describe the principles and experience of the automatic function of the "SEP - Search" program. The positive result, showing the exact beginning of an SEP event on the Emilio Segre Observ 10.8GV ), is determined now automatically by simultaneously increasing by 2.5 St.Dev. in two sections of the ne search "programnext uses 1-mindata for checking whether or not the observed increase reflects the beginning Research "automatically starts to work online. We determine also the probabilities of false and missed alerts.

  18. EEG/ERP adaptive noise canceller design with controlled search space (CSS) approach in cuckoo and other optimization algorithms.

    PubMed

    Ahirwal, M K; Kumar, Anil; Singh, G K

    2013-01-01

    This paper explores the migration of adaptive filtering with swarm intelligence/evolutionary techniques employed in the field of electroencephalogram/event-related potential noise cancellation or extraction. A new approach is proposed in the form of controlled search space to stabilize the randomness of swarm intelligence techniques especially for the EEG signal. Swarm-based algorithms such as Particles Swarm Optimization, Artificial Bee Colony, and Cuckoo Optimization Algorithm with their variants are implemented to design optimized adaptive noise canceler. The proposed controlled search space technique is tested on each of the swarm intelligence techniques and is found to be more accurate and powerful. Adaptive noise canceler with traditional algorithms such as least-mean-square, normalized least-mean-square, and recursive least-mean-square algorithms are also implemented to compare the results. ERP signals such as simulated visual evoked potential, real visual evoked potential, and real sensorimotor evoked potential are used, due to their physiological importance in various EEG studies. Average computational time and shape measures of evolutionary techniques are observed 8.21E-01 sec and 1.73E-01, respectively. Though, traditional algorithms take negligible time consumption, but are unable to offer good shape preservation of ERP, noticed as average computational time and shape measure difference, 1.41E-02 sec and 2.60E+00, respectively. PMID:24407307

  19. Large space structure model reduction and control system design based upon actuator and sensor influence functions

    NASA Technical Reports Server (NTRS)

    Yam, Y.; Lang, J. H.; Johnson, T. L.; Shih, S.; Staelin, D. H.

    1983-01-01

    A model reduction procedure based on aggregation with respect to sensor and actuator influences rather than modes is presented for large systems of coupled second-order differential equations. Perturbation expressions which can predict the effects of spillover on both the aggregated and residual states are derived. These expressions lead to the development of control system design constraints which are sufficient to guarantee, to within the validity of the perturbations, that the residual states are not destabilized by control systems designed from the reduced model. A numerical example is provided to illustrate the application of the aggregation and control system design method.

  20. Study of wind change for the development of loads reduction techniques for the space shuttle

    NASA Technical Reports Server (NTRS)

    Adelfang, S. I.

    1987-01-01

    Wind change statistics are analyzed for Vandenberg AFB, California (VAFB) and Kennedy Space Center, Florida (KSC). Means and standard deviations of wind component change and vector wind change modulus within 3-9 and 9-16 km altitude bands are tabulated. The contribution to 3.5 hr wind component change by wind perturbations in various wavelength bands is evaluated. Probability distributions of maximum 3.5 hr wind change in an altitude band are presented and a model for wind change at a specified altitude is tested with data derived from six data bases from VAFB and Santa Monica, California.

  1. Autonomous image data reduction by analysis and interpretation. [for space missions

    NASA Technical Reports Server (NTRS)

    Eberlein, Susan; Yates, Gigi; Ritter, Niles

    1988-01-01

    Image data is a critical component of the scientific information acquired by space missions. Compression of image data is required due to the limited bandwidth of the data transmission channel and limited memory space on the acquisition vehicle. This need becomes more pressing when dealing with multispectral data where each pixel may comprise 300 or more bytes. An autonomous, real time, on-board image analysis system for an exploratory vehicle such as a Mars Rover is developed. The completed system will be capable of interpreting image data to produce reduced representations of the image, and of making decisions regarding the importance of data based on current scientific goals. Data from multiple sources, including stereo images, color images, and multispectral data, are fused into single image representations. Analysis techniques emphasize artificial neural networks. Clusters are described by their outlines and class values. These analysis and compression techniques are coupled with decision-making capacity for determining importance of each image region. Areas determined to be noise or uninteresting can be discarded in favor of more important areas. Thus limited resources for data storage and transmission are allocated to the most significant images.

  2. Space Radiation Cancer Risk Projections for Exploration Missions: Uncertainty Reduction and Mitigation

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis; Badhwar, Gautam; Saganti, Premkumar; Schimmerling, Walter; Wilson, John; Peterson, Leif; Dicello, John

    2002-01-01

    In this paper we discuss expected lifetime excess cancer risks for astronauts returning from exploration class missions. For the first time we make a quantitative assessment of uncertainties in cancer risk projections for space radiation exposures. Late effects from the high charge and energy (HZE) ions present in the galactic cosmic rays including cancer and the poorly understood risks to the central nervous system constitute the major risks. Methods used to project risk in low Earth orbit are seen as highly uncertain for projecting risks on exploration missions because of the limited radiobiology data available for estimating HZE ion risks. Cancer risk projections are described as a product of many biological and physical factors, each of which has a differential range of uncertainty due to lack of data and knowledge. Monte-Carlo sampling from subjective error distributions represents the lack of knowledge in each factor to quantify risk projection overall uncertainty. Cancer risk analysis is applied to several exploration mission scenarios. At solar minimum, the number of days in space where career risk of less than the limiting 3% excess cancer mortality can be assured at a 95% confidence level is found to be only of the order of 100 days.

  3. Fatigue-induced glenohumeral and scapulothoracic kinematic variability: Implications for subacromial space reduction.

    PubMed

    Chopp-Hurley, Jaclyn N; O'Neill, John M; McDonald, Alison C; Maciukiewicz, Jacquelyn M; Dickerson, Clark R

    2016-08-01

    Superior humeral head translation and scapula reorientation can reduce the subacromial space. While these kinematic abnormalities exist in injured populations, the effect of muscle fatigue is unclear. Additionally, these mechanisms were typically studied independently, thereby neglecting potential covariance. This research evaluated the influence of upper extremity muscle fatigue on glenohumeral and scapulothoracic kinematics and defined their relationship. Radiography and motion tracking systems captured these kinematic relationships, during scapula plane elevation, both before and after fatigue. Fatigue-induced changes in humeral head position, scapular orientation and the minimum subacromial space width were measured. High inter-subject variability existed for each measure which precluded identification of mean differences at the population level. However, significant scapular upward rotation occurred following fatigue (p=0.0002). Despite similar population mean results, between 39% and 57% of participants exhibited fatigue-related changes in disadvantageous orientations. Additionally, correlations between measures were generally fair (0.21-0.40) and highly dependent on elevation, likely attributed to the variable fatigue responses. Overall, the data confirms that fatigue-induced changes in kinematics poses highly variable risk of subacromial impingement syndrome across individuals. Thus, solely considering the "average" or mean population response likely underestimates potentially injurious fatigue consequences. PMID:26320811

  4. Reduction of scattering to an invariant finite displacement in an ambient space-time

    PubMed Central

    Segal, I. E.

    1984-01-01

    The scattering transformation S for a wave equation in Minkowski space M0 is reducible (rigorously in the classical case, necessarily partially heuristically in the nonlinear quantum case) to the action of a distinguished finite transformation ζ in the ambient universal cosmos M. M0 is invariantly imbedded in M, relative to any given point of observation, and the space-like surfaces x0 = s in M0 converge as s → ±∞ to finite light cones C± in M. The generator ζ of the infinite cyclic center of the connected group of all casuality-preserving transformations in M (isomorphic to SU(2,2)/Z2) carries C- into C+ and acts on solutions of relativistic wave equations as S, in an invariant bundle formulation. The establishment of S is simplified, the symmetry and regularity properties of S are enhanced, the scope of the scattering concept is extended to important equations such as those of Yang-Mills (lacking an invariant separation into free and interaction components), and the treatment of bound and scattering states is more unified. PMID:16593531

  5. Efficient and robust reforming catalyst in severe reaction conditions by nanoprecursor reduction in confined space.

    PubMed

    Dacquin, Jean-Philippe; Sellam, Djamila; Batiot-Dupeyrat, Catherine; Tougerti, Asma; Duprez, Daniel; Royer, Sébastien

    2014-02-01

    The in situ autocombustion synthesis route is shown to be an easy and efficient way to produce nanoscaled nickel oxide containing lanthanum-doped mesoporous silica composite. Through this approach, ~3 nm NiO particles homogeneously dispersed in the pores of silica are obtained, while lanthanum is observed to cover the surface of the silica pore wall. Subsequent reduction of such composite precursors under hydrogen generates Ni(0) nanoparticles of a comparable size. Control over the size and size distribution of metallic nanoparticles clearly improved catalytic activity in the methane dry reforming reaction. In addition, these composite materials exhibit excellent stability under severe reaction conditions. This was achieved through the presence of LaOx species, which reduced active-site carbon poisoning, and the confinement effect of the mesoporous support, which reduced metallic particle sintering. PMID:24323543

  6. Orienting of visuo-spatial attention in complex 3D space: Search and detection

    PubMed Central

    Ogawa, Akitoshi; Macaluso, Emiliano

    2015-01-01

    The ability to detect changes in the environment is necessary for appropriate interactions with the external world. Changes in the background go more unnoticed than foreground changes, possibly because attention prioritizes processing of foreground/near stimuli. Here, we investigated the detectability of foreground and background changes within natural scenes and the influence of stereoscopic depth cues on this. Using a flicker paradigm, we alternated a pair of images that were exactly same or differed for one single element (i.e., a color change of one object in the scene). The participants were asked to find the change that occurred either in a foreground or background object, while viewing the stimuli either with binocular and monocular cues (bmC) or monocular cues only (mC). The behavioral results showed faster and more accurate detections for foreground changes and overall better performance in bmC than mC conditions. The imaging results highlighted the involvement of fronto-parietal attention controlling networks during active search and target detection. These attention networks did not show any differential effect as function of the presence/absence of the binocular cues, or the detection of foreground/background changes. By contrast, the lateral occipital cortex showed greater activation for detections in foreground compared to background, while area V3A showed a main effect of bmC vs. mC, specifically during search. These findings indicate that visual search with binocular cues does not impose any specific requirement on attention-controlling fronto-parietal networks, while the enhanced detection of front/near objects in the bmC condition reflects bottom-up sensory processes in visual cortex. Hum Brain Mapp 36:2231–2247, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. PMID:25691253

  7. Search for non-Gaussianity in pixel, harmonic, and wavelet space: Compared and combined

    NASA Astrophysics Data System (ADS)

    Cabella, Paolo; Hansen, Frode; Marinucci, Domenico; Pagano, Daniele; Vittorio, Nicola

    2004-03-01

    We present a comparison between three approaches to test the non-Gaussianity of cosmic microwave background data. The Minkowski functionals, the empirical process method, and the skewness of wavelet coefficients are applied to maps generated from nonstandard inflationary models and to Gaussian maps with point sources included. We discuss the different power of the pixel, harmonic, and wavelet space methods on these simulated almost full-sky data (with Planck-like noise). We also suggest a new procedure consisting of a combination of statistics in pixel, harmonic, and wavelet space.

  8. Evolutionary computing for the design search and optimization of space vehicle power subsystems

    NASA Technical Reports Server (NTRS)

    Kordon, Mark; Klimeck, Gerhard; Hanks, David; Hua, Hook

    2004-01-01

    Evolutionary computing has proven to be a straightforward and robust approach for optimizing a wide range of difficult analysis and design problems. This paper discusses the application of these techniques to an existing space vehicle power subsystem resource and performance analysis simulation in a parallel processing environment. Out preliminary results demonstrate that this approach has the potential to improve the space system trade study process by allowing engineers to statistically weight subsystem goals of mass, cost and performance then automatically size power elements based on anticipated performance of the subsystem rather than on worst-case estimates.

  9. Strategy for the reduction of total integrated fluid logistics to the Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Gould, Marston J.; Shannon, David T., Jr.

    1993-01-01

    The use of an integrated environmental control and life support system (ECLSS) and secondary propulsion system (SRS) on the Space Station Freedom (SSF) has many potential advantages. Through the metabolism of food, the crew on-board the station will produce carbon dioxide as a waste gas and an excess of water in the form of urine and condensate. The processing of these waste fluids by the ECLSS could produce quantities of oxygen that would eliminate the need for cryogenic oxygen resupply and hydrogen, carbon dioxide, and/or methane that could be used with the addition of a resistojet system to provide a constant low thrust for station. This additional thrust would represent significant savings in required hydrazine resupply.

  10. Reduction of spillover effects on independent modal space control through optimal placement of sensors and actuators

    NASA Astrophysics Data System (ADS)

    Cinquemani, S.; Ferrari, D.; Bayati, I.

    2015-08-01

    The independent modal space control (IMSC) technique can be profitably used to suppress vibration in flexible structures by increasing the damping of the modes involved, without changing the corresponding natural frequencies and modal shapes. Reducing vibration means reducing the associated noise and enhancing the performance of the system and its fatigue durability. The main limitations of this approach are related to spillover effects due to the dynamics of unmodeled modes. This work investigates analytically how spillover effects in IMSC are closely related to the number and the position of thesensors and actuators involved, in addition to the reduced model adopted to synthesize the control itself. The performance of the IMSC technique is optimized by means of genetic algorithms to reduce spillover effects, finding the best placements for sensors and actuators. Theoretical aspects are supported by numerical simulations.

  11. Reduction of potatos due to hydric soil erosion using space technology

    NASA Astrophysics Data System (ADS)

    Guyot, E. C.; Ríos, V. H.; Zelaya, D. K.; Soria, F.; Ríos, E.; Padilla, P.

    The potato's crop is in the fourth ranking of economic importance in the agricultural Gross Income of Tucuman. The geographical location of its production area makes essential the handling of the hydric soil erosion problems. The purpose of this work is to improve potato crop irrigation management using space information combined with farm practice. The field measurements were carried out using Wide Area Differential Global Position Systems FUGRO OMNISTAR, total station, and double frequency Global Position Systems. The crop irrigation was pursued through scheduling irrigation's software whose input comes from satellites of the Matutinal Constellation (LandSat 7, SACC and TERRA). The preliminary results allowed reprograming the irrigation practices for the new crop's campaign in order to decrease hydric soil erosion.

  12. Evolutionary computing for the design search and optimization of space vehicle power subsystems

    NASA Technical Reports Server (NTRS)

    Kordon, M.; Klimeck, G.; Hanks, D.

    2004-01-01

    Evolutionary computing has proven to be a straightforward and robust approach for optimizing a wide range of difficult analysis and design problems. This paper discusses the application of these techniques to an existing space vehicle power subsystem resource and performance analysis simulation in a parallel processing environment.

  13. Conformational Space and Stability of ETD Charge Reduction Products of Ubiquitin

    NASA Astrophysics Data System (ADS)

    Lermyte, Frederik; Łącki, Mateusz Krzysztof; Valkenborg, Dirk; Gambin, Anna; Sobott, Frank

    2016-08-01

    Owing to its versatility, electron transfer dissociation (ETD) has become one of the most commonly utilized fragmentation techniques in both native and non-native top-down mass spectrometry. However, several competing reactions—primarily different forms of charge reduction—occur under ETD conditions, as evidenced by the distorted isotope patterns usually observed. In this work, we analyze these isotope patterns to compare the stability of nondissociative electron transfer (ETnoD) products, specifically noncovalent c/z fragment complexes, across a range of ubiquitin conformational states. Using ion mobility, we find that more extended states are more prone to fragment release. We obtain evidence that for a given charge state, populations of ubiquitin ions formed either directly by electrospray ionization or through collapse of more extended states upon charge reduction, span a similar range of collision cross-sections. Products of gas-phase collapse are, however, less stabilized towards unfolding than the native conformation, indicating that the ions retain a memory of previous conformational states. Furthermore, this collapse of charge-reduced ions is promoted if the ions are `preheated' using collisional activation, with possible implications for the kinetics of gas-phase compaction.

  14. The Reduction and Treatment of Serious Mental Illness during Long Duration Space Mission.

    NASA Astrophysics Data System (ADS)

    Mardon, Austin; Nichol, Kenneth; Mardon, Catherine; Mardon, Austin

    It is well known in the history of terrestrial naval expeditions that members of long expeditions could and did suffered from serious mental illnesses. Depression and even psychosis could inflict crew members, and in serious cases this sometimes resulted in violence directed towards others or themselves. There was little that the medical practitioners of the time could do to alleviate these illnesses. Modern psychiatry operates within a paradigm of the normalcy of the modern western standard of living. When we place humans outside these normal experiences, we place them in vulnerable positions. For the foreseeable future, spaceflight will continue to result in extremely physically, mentally and spiritually arduous expeditions. As we start our journey towards Mars and beyond, the time humans will be in the isolation of space, and subjected to these extraordinary stresses, will increase. The recent incident where an American astronaut had a mental collapse and was criminally charged is indicative of this real possibility. One solution could be to have more pre-screening but this only goes so far, especially when the rigorous training and the actual mission might cause psychological problems that were never present before hand. Eastern and Western philosophies and religious systems can provide a framework to draw upon to strengthen the mental and spiritual psyche of the astronauts on a long duration expedition. Meditative techniques and prayer techniques, if within the belief system of the astronaut, might serve to prevent or ameliorate the severity of a mental collapse should it occur during a space mission. Many of the American astronauts that went to the Moon reported having intense emotional and spiritual reactions based on the intensity of their experiences. For several of these men, the courses of their lives were changed. What astronauts will face by going back to the Moon and further a field to Mars, will be dangerous and extremely mentally taxing. At the

  15. SARSAT - Using space for the search and rescue of lives in distress

    NASA Astrophysics Data System (ADS)

    Flatow, F.; Trudell, B.

    A major cooperative effort between west and east bloc nations in developing a new space system for detecting ships and aircraft in distress is discussed. The compatible working of the SARSAT system developed by Canada, France, and the US and the COSPAS system developed by the Soviet bloc is summarized, and the SARSAT system is described. The method of location determination is presented, and the ELT and EPIRB, space segment, local user terminal, and mission control center subsystems of the SARSAT system are surveyed, showing block diagrams and data on spacecraft orbital parameters and ELT/EPIRB BECON characteristics. The current problem of ground-based interference is discussed. An outline of future development activities leading to the implementation of a fully operational system is included.

  16. SARSAT - Using space for the search and rescue of lives in distress

    NASA Technical Reports Server (NTRS)

    Flatow, F.; Trudell, B.

    1984-01-01

    A major cooperative effort between west and east bloc nations in developing a new space system for detecting ships and aircraft in distress is discussed. The compatible working of the SARSAT system developed by Canada, France, and the US and the COSPAS system developed by the Soviet bloc is summarized, and the SARSAT system is described. The method of location determination is presented, and the ELT and EPIRB, space segment, local user terminal, and mission control center subsystems of the SARSAT system are surveyed, showing block diagrams and data on spacecraft orbital parameters and ELT/EPIRB BECON characteristics. The current problem of ground-based interference is discussed. An outline of future development activities leading to the implementation of a fully operational system is included.

  17. Marine Microbial Mats and the Search for Evidence of Life in Deep Time and Space

    NASA Technical Reports Server (NTRS)

    Des Marais, David J.

    2011-01-01

    Cyanobacterial mats in extensive seawater evaporation ponds at Guerrero Negro, Baja California, Mexico, have been excellent subjects for microbial ecology research. The studies reviewed here have documented the steep and rapidly changing environmental gradients experienced by mat microorganisms and the very high rates of biogeochemical processes that they maintained. Recent genetic studies have revealed an enormous diversity of bacteria as well as the spatial distribution of Bacteria, Archaea and Eukarya. These findings, together with emerging insights into the intimate interactions between these diverse populations, have contributed substantially to our understanding of the origins, environmental impacts, and biosignatures of photosynthetic microbial mats. The biosignatures (preservable cells, sedimentary fabrics, organic compounds, minerals, stable isotope patterns, etc.) potentially can serve as indicators of past life on early Earth. They also can inform our search for evidence of any life on Mars. Mars exploration has revealed evidence of evaporite deposits and thermal spring deposits; similar deposits on Earth once hosted ancient microbial mat ecosystems.

  18. Searching for Bio-Precursors and Complex Organic Molecules in Space using the GBT

    NASA Technical Reports Server (NTRS)

    Cordiner, M.; Charnley, S.; Kisiel, Z.

    2012-01-01

    Using the latest microwave receiver technology, large organic molecules with abundances as low as approx. 10(exp -11) times that of molecular hydrogen are detectable in cold interstellar clouds via their rotational emission line spectra. We report new observations to search for complex molecules, including molecules of possible pre-biotic importance, using the newly-commissioned Kband focal plane array (KFPA) of the NRAO Robert C. Byrd Green Bank Telescope. Spectra are presented of the dense molecular cloud TMC-1, showing strict upper limits on the level of emission from nitrogen-bearing rings pyrimidine, quinoline and iso-quinoline, carbon-chain oxides C60, C70, HC60 and HC70, and the carbon-chain anion C4H-. The typical RMS brightness temperature noise levels we achieved are approx. 1 mK at around 20 GHz.

  19. The space microwave interferometer and the search for cosmic background gravitational wave radiation

    NASA Technical Reports Server (NTRS)

    Anderson, Allen Joel

    1989-01-01

    Present and planned investigations which use interplanetary spacecraft for gravitational wave searches are severely limited in their detection capability. This limitation has to do both with the Earth-based tracking procedures used and with the configuration of the experiments themselves. It is suggested that a much improved experiment can now be made using a multiarm interferometer designed with current operating elements. An important source of gravitational wave radiation, the cosmic background, may well be within reach of detection with these procedures. It is proposed to make a number of experimental steps that can now be carried out using TDRSS spacecraft and would conclude in the establishment of an operating multiarm microwave interferometer. This interferometer is projected to have a sensitivity to cosmic background gravitational wave radiation with an energy of less than 10(exp -4) cosmic closure density and to periodic waves generating spatial strain approaching 10(exp -19) in the range 0.1 to 0.001 Hz.

  20. MEPSA: A flexible peak search algorithm designed for uniformly spaced time series

    NASA Astrophysics Data System (ADS)

    Guidorzi, C.

    2015-04-01

    We present a novel algorithm aimed at identifying peaks within a uniformly sampled time series affected by uncorrelated Gaussian noise. The algorithm, called "MEPSA" (multiple excess peak search algorithm), essentially scans the time series at different timescales by comparing a given peak candidate with a variable number of adjacent bins. While this has originally been conceived for the analysis of gamma-ray burst light (GRB) curves, its usage can be readily extended to other astrophysical transient phenomena, whose activity is recorded through different surveys. We tested and validated it through simulated featureless profiles as well as simulated GRB time profiles. We showcase the algorithm's potential by comparing with the popular algorithm by Li and Fenimore, that is frequently adopted in the literature. Thanks to its high flexibility, the mask of excess patterns used by MEPSA can be tailored and optimised to the kind of data to be analysed without modifying the code. The C code is made publicly available.

  1. Solar dynamic power for space stations. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    Not Available

    1994-08-01

    The bibliography contains citations concerning hardware implementation and theoretical analyses of a proposed power supply for the NASA-sponsored space station. Performance and reliability predictions, life-cycle analyses, and comparisons with other types of power supplies are discussed. Descriptions of specific components, including heat pipes, thermal radiators, and steam turbines are also included. (Contains 250 citations and includes a subject term index and title list.)

  2. Passive solar space heating and cooling. (Latest citations from the NTIS Bibliographic database). NewSearch

    SciTech Connect

    Not Available

    1994-10-01

    The bibliography contains citations concerning the passive use of solar energy for space heating and cooling in buildings, houses, and homes. Citations discuss the design, performance, models, and economic analysis of heating and cooling systems. Topics include solar architecture, energy consumption analysis, energy conservation, and heat recovery. Also included are thermal comfort, quality of life, and housing for the elderly. (Contains a minimum of 209 citations and includes a subject term index and title list.)

  3. Robots for hazardous duties: Military, space, and nuclear facility applications. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1993-09-01

    The bibliography contains citations concerning the design and application of robots used in place of humans where the environment could be hazardous. Military applications include autonomous land vehicles, robotic howitzers, and battlefield support operations. Space operations include docking, maintenance, mission support, and intra-vehicular and extra-vehicular activities. Nuclear applications include operations within the containment vessel, radioactive waste operations, fueling operations, and plant security. Many of the articles reference control techniques and the use of expert systems in robotic operations. Applications involving industrial manufacturing, walking robots, and robot welding are cited in other published searches in this series. (Contains a minimum of 183 citations and includes a subject term index and title list.)

  4. Searches for gravitational waves from binary black hole coalescences with ground-based laser interferometers across a wide parameter space

    NASA Astrophysics Data System (ADS)

    Ray Pitambar Mohapatra, Satyanarayan

    This is an exciting time for Gravitational Wave (GW) theory and observations. From a theoretical standpoint, the grand-challenge problem of the full evolution of a Binary Black Hole (BBH) system has been solved numerically, and a variety of source simulations are made available steadfastly. On the observational side, the first generation of state-of-the-art GW detectors, LIGO and Virgo, have achieved their design goal, collected data and provided astrophysically meaningful limits. The second generation of detectors are expected to start running by 2015. Inspired by this zeitgeist, this thesis focuses on the detection of potential GW signatures from the coalescence of BBH in ground-based laser interferometers. The LIGO Scientific Collaboration has implemented different algorithms to search for transient GW signatures, targeting different portions of the BBH coalescence waveform. This thesis has used the existing algorithms to study the detection potential of GW from colliding BBH in LIGO in a wide range of source parameters, such as mass and spin of the black holes, using a sample of data from the last two months of the S5 LIGO science run (14 Aug 2007 to 30 Sept 2007). This thesis also uses numerical relativity waveforms made available via the Numerical INJection Analysis project (NINJA). Methods such as the Chirplet based analysis and the use of multivariate classifiers to optimize burst search algorithms have been introduced in this thesis. These performance studies over a wide parameter space were designed to optimize the discovery potential of ground-based GW detectors and defining strategies for the search of BBH signatures in advanced LIGO data, as a step towards the realization of GW astronomy.

  5. Groundwater Monitoring Network Design Using a Space-Filling/ Bias-Reduction Heuristic

    NASA Astrophysics Data System (ADS)

    Yan, T.; Singh, A.; Kelley, V.; Deeds, N.

    2012-12-01

    Groundwater monitoring network design is one of the primary goals of groundwater management. In this study, a heuristic method for selecting wells to monitor groundwater flow is developed. The approach selects wells to a) maximize spread within the monitoring area (space-filling objective), b) reduce bias in estimate of groundwater level (drawdown objective) by selecting pairs of well proximal and distant from pumping areas. By selecting pairs of monitoring wells, this method is able to capture the largest and smallest drawdown in the study area while ensuring the newly added monitoring wells are at the greatest distance from existing monitoring wells. One of the advantages of this method is that it does not require water level information, obtained either from field measurements or groundwater model runs, which might be unavailable at the time of the monitoring network design; instead, this method utilizes pumping rates and locations thus can take future planning into consideration. If water level data is available then that may be included by considering it in the drawdown objective. A FORTRAN code is developed to implement this method. By changing the weighting factors, users have the flexibility on deciding the importance of pumping and spatial information to their network designs. The method has been successfully applied to monitoring network design in Upper Trinity County Groundwater Conservation District in Texas. Monitoring wells were selected from thousands of existing wells and added to the current monitoring network. The results support the decision maker on the number and distribution of a new groundwater network using existing wells. The study can be extended to improve the application of desired future condition (DFC) for Groundwater Conservation Districts in Texas.

  6. Ab initio materials design using conformational space annealing and its application to searching for direct band gap silicon crystals

    NASA Astrophysics Data System (ADS)

    Lee, In-Ho; Oh, Young Jun; Kim, Sunghyun; Lee, Jooyoung; Chang, K. J.

    2016-06-01

    Lately, the so-called inverse method of materials design has drawn much attention, where specific material properties are initially assigned and target materials are subsequently searched for. Although this method has been successful for some problems, the success of designing complex crystal structures containing many atoms is often limited by the efficiency of the search method utilized. Here we combine the global optimization method of conformational space annealing (CSA) with first-principles quantum calculations and report a new scheme named AMADEUS (Ab initio MAterials DEsign Using cSa). We demonstrate the utility of AMADEUS through the discovery of direct band gap Si crystals. The newly-designed direct gap Si allotropes show excellent optical properties and the spectroscopic limited maximum efficiencies comparable to those of best-known non-silicon photovoltaic materials. Our scheme not only provides a new perspective for the inverse problem of materials design but also may serve as a new tool for the computational design of a wide range of materials.

  7. Space fullerenes: a computer search for new Frank-Kasper structures.

    PubMed

    Dutour Sikirić, Mathieu; Delgado-Friedrichs, Olaf; Deza, Michel

    2010-09-01

    A Frank-Kasper structure is a 3-periodic tiling of the Euclidean space E3 by tetrahedra such that the vertex figure of any vertex belongs to four specified patterns with, respectively, 20, 24, 26 and 28 faces. Frank-Kasper structures occur in the crystallography of metallic alloys and clathrates. A new computer enumeration method has been devised for obtaining Frank-Kasper structures of up to 20 cells in a reduced fundamental domain. Here, the 84 obtained structures have been compared with the known 27 physical structures and the known special constructions by Frank-Kasper-Sullivan, Shoemaker-Shoemaker, Sadoc-Mosseri and Deza-Shtogrin. PMID:20720324

  8. Oxidation and reduction under cover: Chemistry at the confined space between ultra-thin nanoporous silicates and Ru(0001)

    DOE PAGESBeta

    J. Anibal Boscoboinik; Zhong, Jian -Qiang; Kestell, John; Waluyo, Iradwikanari; Wilkins, Stuart; Mazzoli, Claudio; Barbour, Andi; Kaznatcheev, Konstantine; Shete, Meere; Tsapatsis, Michael

    2016-03-23

    The oxidation and reduction of Ru(0001) surfaces at the confined space between two-dimensional nanoporous silica frameworks and Ru(0001) have been investigated using synchrotron-based ambient pressure X-ray photoelectron spectroscopy (AP-XPS). The porous nature of the frameworks and the weak interaction between the silica and the ruthenium substrate allow oxygen and hydrogen molecules to go through the nanopores and react with the metal at the interface between the silica framework and the metal surface. In this work, three types of two-dimensional silica frameworks have been used to study their influence in the oxidation and reduction of the ruthenium surface at elevated pressuresmore » and temperatures. These frameworks are bilayer silica (0.5 nm thick), bilayer aluminosilicate (0.5 nm thick), and zeolite MFI nanosheets (3 nm thick). It is found that the silica frameworks stay essentially intact under these conditions, but they strongly affect the oxidation of ruthenium, with the 0.5 nm thick aluminosilicate bilayer completely inhibiting the oxidation. Furthermore, the latter is believed to be related to the lower chemisorbed oxygen content arising from electrostatic interactions between the negatively charged aluminosilicate framework and the Ru(0001) substrate.« less

  9. Comparative study of two image space noise reduction methods for computed tomography: bilateral filter and nonlocal means.

    PubMed

    Giraldo, Juan C Ramirez; Kelm, Zachary S; Guimaraes, Luis S; Yu, Lifeng; Fletcher, Joel G; Erickson, Bradley J; McCollough, Cynthia H

    2009-01-01

    Optimal noise control is important for improving image quality and reducing radiation dose in computed tomography. Here we investigated two image space based nonlinear filters for noise reduction: the bilateral filter (BF) and the nonlocal means (NLM) algorithm. Images from both methods were compared against those from a commercially available weighted filtered backprojection (WFBP) method. A standard phantom for quality assurance testing was used to quantitatively compare noise and spatial resolution, as well as low contrast detectability (LCD). Additionally, an image dataset from a patient's abdominal CT exam was used to assess the effectiveness of the filters on full dose and simulated half dose acquisitions. We found that both the BF and NLM methods improve the tradeoff between noise and high contrast spatial resolution with no significant difference in LCD. Results from the patient dataset demonstrated the potential of dose reduction with the denoising methods. Care must be taken when choosing the NLM parameters in order to minimize the generation of artifacts that could possibly compromise diagnostic value. PMID:19964998

  10. Space Shuttle main engine OPAD: The search for a hardware enhanced plume

    NASA Astrophysics Data System (ADS)

    Powers, W. T.; Cooper, A. E.; Wallace, Tim L.; Buntine, W. L.; Whitaker, K. W.

    1993-11-01

    The process of applying spectroscopy to the Space Shuttle Main Engine (SSME) for plume diagnostics, as it exists today, originated at Marshall Space Flight Center in Huntsville, Alabama, and its implementation was assured largely through the efforts of Sverdrup AEDC, in Tullahoma, Tennessee. This team continues to lead and guide efforts in the plume diagnostics arena. The process, Optical Plume Anomaly Detection (OPAD), formed the basis for various activities in the development of ground-based systems as well as the development of in-flight plume spectroscopy. OPAD currently provides and will continue to provide valuable information relative to future systems definitions, instrumentation development, code validation, and data diagnostic processing. OPAD is based on the detection of anomalous atomic and molecular species in the SSME plume using two complete, stand-alone optical spectrometers. To-date OPAD has acquired data on 44 test firings of the SSME at the Technology Test Bed (TTB) at MSFC. The purpose of this paper will be to provide an introduction to the OPAD system by discussing the process of obtaining data as well as the methods of examining and interpreting the data. It will encompass such issues as selection of instrumentation correlation of data to nominal engine operation, investigation of SSME component erosion via OPAD spectral data, necessity and benefits of plume seeding, application of artificial intelligence (AI) techniques to data analysis, and the present status of efforts to quantify specie erosion utilizing standard plume and chemistry codes as well as radiative models currently under development.

  11. Improved ligand binding energies derived from molecular dynamics: replicate sampling enhances the search of conformational space.

    PubMed

    Adler, Marc; Beroza, Paul

    2013-08-26

    Does a single molecular trajectory provide an adequate sample conformational space? Our calculations indicate that for Molecular Mechanics--Poisson-Boltzmann Surface Area (MM-PBSA) measurement of protein ligand binding, a single molecular dynamics trajectory does not provide a representative sampling of phase space. For a single trajectory, the binding energy obtained by averaging over a number of molecular dynamics frames in an equilibrated system will converge after an adequate simulation time. A separate trajectory with nearly identical starting coordinates (1% randomly perturbed by 0.001 Å), however, can lead to a significantly different calculated binding energy. Thus, even though the calculated energy converges for a single molecular dynamics run, the variation across separate runs implies that a single run inadequately samples the system. The divergence in the trajectories is reflected in the individual energy components, such as the van der Waals and the electrostatics terms. These results indicate that the trajectories sample different conformations that are not in rapid exchange. Extending the length of the dynamics simulation does not resolve the energy differences observed between different trajectories. By averaging over multiple simulations, each with a nearly equivalent starting structure, we find the standard deviation in the calculated binding energy to be ∼1.3 kcal/mol. The work presented here indicates that combining MM-PBSA with multiple samples of the initial starting coordinates will produce more precise and accurate estimates of protein/ligand affinity. PMID:23845109

  12. NASA Space Science and a Search for Ram-Pressure Stripping in the Hydra I Cluster

    NASA Technical Reports Server (NTRS)

    Brown, Beth

    2005-01-01

    The NASA Goddard Space Flight Center's Sciences and Exploration Directorate seeks to expand scientific knowledge through observational and theoretical research in the study of the Earth-Sun system, the solar system and the origins of life, and the birth and evolution of the universe. This talk will discuss some of the cutting-edge space science research being conducted at Goddard. In addition, I will discuss my research on ram-pressure stripping in cluster elliptical galaxies. Ram-pressure stripping is a method by which hot interstellar gas can be removed from a galaxy moving through a group or cluster of galaxies. Indirect evidence of ram-pressure stripping includes lowered X-ray brightness in a galaxy due to less X-ray emitting gas remaining in the galaxy. Here we present the initial results of our program to determine whether cluster elliptical galaxies have lower hot gas masses than their counterparts in less rich environments. This test requires the use of the high-resolution imaging of the Chandra Observatory and we present our analysis of the galaxies in the nearby cluster Hydra I.

  13. Space Shuttle main engine OPAD: The search for a hardware enhanced plume

    NASA Technical Reports Server (NTRS)

    Powers, W. T.; Cooper, A. E.; Wallace, Tim L.; Buntine, W. L.; Whitaker, K. W.

    1993-01-01

    The process of applying spectroscopy to the Space Shuttle Main Engine (SSME) for plume diagnostics, as it exists today, originated at Marshall Space Flight Center in Huntsville, Alabama, and its implementation was assured largely through the efforts of Sverdrup AEDC, in Tullahoma, Tennessee. This team continues to lead and guide efforts in the plume diagnostics arena. The process, Optical Plume Anomaly Detection (OPAD), formed the basis for various activities in the development of ground-based systems as well as the development of in-flight plume spectroscopy. OPAD currently provides and will continue to provide valuable information relative to future systems definitions, instrumentation development, code validation, and data diagnostic processing. OPAD is based on the detection of anomalous atomic and molecular species in the SSME plume using two complete, stand-alone optical spectrometers. To-date OPAD has acquired data on 44 test firings of the SSME at the Technology Test Bed (TTB) at MSFC. The purpose of this paper will be to provide an introduction to the OPAD system by discussing the process of obtaining data as well as the methods of examining and interpreting the data. It will encompass such issues as selection of instrumentation correlation of data to nominal engine operation, investigation of SSME component erosion via OPAD spectral data, necessity and benefits of plume seeding, application of artificial intelligence (AI) techniques to data analysis, and the present status of efforts to quantify specie erosion utilizing standard plume and chemistry codes as well as radiative models currently under development.

  14. Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. I. Sample Selection, Data Reduction, and NGC 7078 Results

    NASA Astrophysics Data System (ADS)

    Bellini, A.; Anderson, J.; van der Marel, R. P.; Watkins, L. L.; King, I. R.; Bianchini, P.; Chanamé, J.; Chandar, R.; Cool, A. M.; Ferraro, F. R.; Ford, H.; Massari, D.

    2014-12-01

    We present the first study of high-precision internal proper motions (PMs) in a large sample of globular clusters, based on Hubble Space Telescope (HST) data obtained over the past decade with the ACS/WFC, ACS/HRC, and WFC3/UVIS instruments. We determine PMs for over 1.3 million stars in the central regions of 22 clusters, with a median number of ~60,000 stars per cluster. These PMs have the potential to significantly advance our understanding of the internal kinematics of globular clusters by extending past line-of-sight (LOS) velocity measurements to two- or three-dimensional velocities, lower stellar masses, and larger sample sizes. We describe the reduction pipeline that we developed to derive homogeneous PMs from the very heterogeneous archival data. We demonstrate the quality of the measurements through extensive Monte Carlo simulations. We also discuss the PM errors introduced by various systematic effects and the techniques that we have developed to correct or remove them to the extent possible. We provide in electronic form the catalog for NGC 7078 (M 15), which consists of 77,837 stars in the central 2.'4. We validate the catalog by comparison with existing PM measurements and LOS velocities and use it to study the dependence of the velocity dispersion on radius, stellar magnitude (or mass) along the main sequence, and direction in the plane of the sky (radial or tangential). Subsequent papers in this series will explore a range of applications in globular-cluster science and will also present the PM catalogs for the other sample clusters. Based on proprietary and archival observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  15. Living with Stars: Future Space-Based Exoplanet Search and Characterization Missions

    NASA Astrophysics Data System (ADS)

    Fridlund, Malcolm; Rauer, Heike; Erikson, Anders

    The study of exoplanets have now been ongoing for more than 20 years. After a first phase of essentially discovery, a remarkable diversity has been found among the more than 1,700 objects that have been detected. Planetary bodies orbiting other stars have begun to be characterized physically, but the next stage of exploration, given an increase in sensitivities and resolutions will provide for data that can be used for comparative planetology in the real sense of the term, i.e. a direct comparison, both between objects outside the Solar System, as well as with objects within our home system. In this chapter we describe briefly all the space assets that are either in orbit, intended to be launched within the near future and also those that are decided for the intermediate time perspective.

  16. Oases{emdash}A space mission to search for habitable planets of other stars

    SciTech Connect

    Angel, R.; Woolf, N.; Leger, A.

    1996-03-01

    We do not yet know if nearby sun-like stars have planets resembling the solar system. In the past, telescopes have not had the power to resolve weak planet emission next to a bright star{emdash}it is as if from a thousand miles away one tried to see a glow worm next to a searchlight. But a telescope in space could now be built by NASA that could not only see Earth-like planets if they are there, but check if they have abundant water or even an atmosphere with oxygen, produced on Earth by primitive life. The name we have given to such a mission is OASES{emdash}Outpost for the Analysis and Spectroscopy of Exo-planetary Systems. {copyright} {ital 1996 American Institute of Physics.}

  17. Pattern drilling exploration: Optimum pattern types and hole spacings when searching for elliptical shaped targets

    USGS Publications Warehouse

    Drew, L.J.

    1979-01-01

    In this study the selection of the optimum type of drilling pattern to be used when exploring for elliptical shaped targets is examined. The rhombic pattern is optimal when the targets are known to have a preferred orientation. Situations can also be found where a rectangular pattern is as efficient as the rhombic pattern. A triangular or square drilling pattern should be used when the orientations of the targets are unknown. The way in which the optimum hole spacing varies as a function of (1) the cost of drilling, (2) the value of the targets, (3) the shape of the targets, (4) the target occurrence probabilities was determined for several examples. Bayes' rule was used to show how target occurrence probabilities can be revised within a multistage pattern drilling scheme. ?? 1979 Plenum Publishing Corporation.

  18. Searching for Black Holes in Space. The Key Role of X-Ray Observations

    NASA Astrophysics Data System (ADS)

    Pounds, Ken

    2014-09-01

    Although General Relativity had provided the physical basis of black holes, evidence for their existence had to await the Space Era when X-ray observations first directed the attention of astronomers to the unusual binary stars Cygnus X-1 and A0620-00. Subsequently, a number of faint Ariel 5 and Uhuru X-ray sources, mainly at high Galactic latitude, were found to lie close to bright Seyfert galaxies, suggesting the nuclear activity in AGN might also be driven by accretion in the strong gravity of a black hole. Detection of rapid X-ray variability with EXOSAT later confirmed that the accreting object in an AGN is almost certainly a supermassive black hole.

  19. Antimatter and Dark Matter Search in Space: BESS-Polar Results

    NASA Technical Reports Server (NTRS)

    Mitchell, John W.; Yamamoto, Akira

    2009-01-01

    The apex of the Balloon-borne Experiment with a Superconducting Spectrometer program was reached with the Antarctic flight of BESS-Polar II, during the 2007-2008 Austral Summer, that obtained 24.5 days of data on over 4.7 billion cosmic-ray events. The US-Japan BESS Collaboration uses elementary particle measurements to study the early Universe and provides fundamental data on the spectra of light cosmic-ray elements and isotopes. BESS measures the energy spectra of cosmic-ray antiprotons to investigate signatures of possible exotic sources, such as dark-matter candidates, and searches for heavier anti-nuclei that might reach Earth from antimatter domains formed during symmetry breaking processes in the early Universe. Since 1993, BESS has carried out eleven high-latitude balloon flights, two of long duration, that together have defined the study of antiprotons below about 4 GeV, provided standard references for light element and isotope spectra, and set the most sensitive limits on the existence of anti-deuterons and anti-helium, The BESS-Polar II flight took place at Solar Minimum, when the sensitivity of the low-energy antiproton measurements to a primary source is greatest. The rich BESS-Polar II dataset more than doubles the combined data from all earlier BESS flights and has 10-20 times the statistics of BESS data from the previous Solar Minimum. Here, we summarize the scientific results of BESS program, focusing on the results obtained using data from the long-duration flights of BESS-Polar I (2004) and BESS-Polar II.

  20. Improving 3d Spatial Queries Search: Newfangled Technique of Space Filling Curves in 3d City Modeling

    NASA Astrophysics Data System (ADS)

    Uznir, U.; Anton, F.; Suhaibah, A.; Rahman, A. A.; Mioc, D.

    2013-09-01

    The advantages of three dimensional (3D) city models can be seen in various applications including photogrammetry, urban and regional planning, computer games, etc.. They expand the visualization and analysis capabilities of Geographic Information Systems on cities, and they can be developed using web standards. However, these 3D city models consume much more storage compared to two dimensional (2D) spatial data. They involve extra geometrical and topological information together with semantic data. Without a proper spatial data clustering method and its corresponding spatial data access method, retrieving portions of and especially searching these 3D city models, will not be done optimally. Even though current developments are based on an open data model allotted by the Open Geospatial Consortium (OGC) called CityGML, its XML-based structure makes it challenging to cluster the 3D urban objects. In this research, we propose an opponent data constellation technique of space-filling curves (3D Hilbert curves) for 3D city model data representation. Unlike previous methods, that try to project 3D or n-dimensional data down to 2D or 3D using Principal Component Analysis (PCA) or Hilbert mappings, in this research, we extend the Hilbert space-filling curve to one higher dimension for 3D city model data implementations. The query performance was tested using a CityGML dataset of 1,000 building blocks and the results are presented in this paper. The advantages of implementing space-filling curves in 3D city modeling will improve data retrieval time by means of optimized 3D adjacency, nearest neighbor information and 3D indexing. The Hilbert mapping, which maps a subinterval of the [0, 1] interval to the corresponding portion of the d-dimensional Hilbert's curve, preserves the Lebesgue measure and is Lipschitz continuous. Depending on the applications, several alternatives are possible in order to cluster spatial data together in the third dimension compared to its

  1. AsteroidFinder - The Space-Borne Telescope to Search for NEO Asteroids

    NASA Astrophysics Data System (ADS)

    Hartl, M.; Mosebach, H.; Schubert, J.; Michaelis, H.; Mottola, S.; Kührt, E.; Schindler, K.

    2010-10-01

    This paper presents the mission profile as well as the optical configuration of the space-borne AsteroidFinder telescope. Its main objective is to retrieve asteroids with orbits interior to the earth's orbit. The instrument requires high sensitivity to detect asteroids with a limiting magnitude of equal or larger than 18.5mag (V-Band) and astrometric accuracy of 1arcsec (1σ). This requires a telescope aperture greater than 400cm2, high image stability, detector with high quantum efficiency (peak > 90%) and very low noise, which is only limited by zodiacal background. The telescope will observe the sky between 30° and 60° in solar elongation. The telescope optics is based on a Cook type TMA. An effective 2°×2° field of view (FOV) is achieved by a fast F/3.4 telescope with near diffraction-limited performance. The absence of centre obscuration or spiders in combination with an accessible intermediate field plane and exit pupil allow for efficient stray light mitigation. Design drivers for the telescope are the required point spread function (PSF) values, an extremely efficient stray light suppression (due to the magnitude requirement mentioned above), the detector performance, and the overall optical and mechanical stability for all orientations of the satellite. To accommodate the passive thermal stabilization scheme and the necessary structural stability, the materials selection for the telescope main structure and the mirrors are of vital importance. A focal plane with four EMCCD detectors is envisaged. The EMCCD technology features shorter integration times, which is in favor regarding the pointing performance of the satellite. The launch of the mission is foreseen for the year 2013 with a subsequent mission lifetime of at least 1 year.

  2. Connection space reduction mechanism

    NASA Technical Reports Server (NTRS)

    Milam, Malcolm Bruce (Inventor)

    1992-01-01

    A connector assembly comprised of two halves, each respectively including a shell type connector subassembly, one being an active half and the other being a passive half is described. The active half includes an alignment cusp that causes a coupling motion in response to coming in contact with the outer portion of the other half, which causes the respective connectors within the two subassemblies to move toward each other into coupling relationship at twice the rate at which the two subassemblies come together. Both halves are adapted to rotate about and translate along respective mutually orthogonal axes to facilitate an interconnection.

  3. A Search for Transits of GJ 581e and Characterization of the Host Star Variability Using MOST Space Telescope Photometry

    NASA Astrophysics Data System (ADS)

    Dragomir, Diana; Matthews, Jaymie M.; Kuschnig, Rainer; Rowe, Jason F.; Gladman, Brett J.; Guenther, David B.; Moffat, Anthony F. J.; Rucinski, Slavek M.; Sasselov, Dimitar; Weiss, Werner W.

    2012-11-01

    The GJ 581 system has been amply studied since its discovery in 2005: the number of known planets in the system has increased and their orbital parameters are among the most precisely determined for radial-velocity-detected exoplanets. We have acquired MOST space-based photometry during 2007 and 2009, with the aims of measuring the stellar variability and searching for transits of GJ 581e, respectively. We quantify our sensitivity to shallow transit signals using Monte Carlo simulations, and perform a transit search within the 3σ transit windows corresponding to both the circular and Keplerian orbit ephemerides. Our analysis rules out transits for a planet with an orbital period of 3.15 days (GJ 581e) having a radius larger than 1.62 R ⊕ (or a density lower than 2.39 g cm-3 for an orbital inclination of 90°) to 2σ confidence. Thus, if the planet transits, we can exclude hydrogen, helium, and water theoretical model compositions. The MOST photometry also allows us to rule out transits of GJ 581b within the Keplerian orbit-derived transit window for impact parameter values smaller than ~0.4 and confirm previous results which exclude transits for this planet within the circular orbit-derived transit window, for all plausible interior compositions. We find that the stellar brightness of GJ 581 is stable to within 1%, a characteristic which is favorable to the development of life in the habitable zone of the system. In the 2009 photometry, we detect a stellar signal with a period of 5.586 ± 0.051 days, which is close to the orbital period of GJ 581b (P = 5.37 days). However, further monitoring of the system is necessary to verify the nature of this variation. Based on data from the MOST satellite, a Canadian Space Agency mission operated by Microsatellite Systems Canada Inc. (MSCI; former Dynacon Inc.) and the Universities of Toronto and British Columbia, with the assistance of the University of Vienna.

  4. A Hubble space telescope search for a sub-Earth-sized exoplanet in the GJ 436 system

    SciTech Connect

    Stevenson, Kevin B.; Bean, Jacob L.; Fabrycky, Daniel; Kreidberg, Laura

    2014-11-20

    The detection of small planets orbiting nearby stars is an important step toward the identification of Earth twins. In previous work using the Spitzer Space Telescope, we found evidence to support at least one sub-Earth-sized exoplanet orbiting the nearby mid-M dwarf star GJ 436. As a follow up, here we used the Hubble Space Telescope (HST) to investigate the existence of one of these candidate planets, UCF-1.01, by searching for two transit signals as it passed in front of its host star. Interpretation of the data hinges critically on correctly modeling and removing the Wide Field Camera 3 (WFC3) instrument systematics from the light curves. Building on previous HST work, we demonstrate that WFC3 analyses need to explore the use of a quadratic function to fit a visit-long time-dependent systematic. This is important for establishing absolute transit and eclipse depths in the white light curves of all transiting systems. The work presented here exemplifies this point by putatively detecting the primary transit of UCF-1.01 with the use of a linear trend. However, using a quadratic trend, we achieve a better fit to the white light curves and a reduced transit depth that is inconsistent with previous Spitzer measurements. Furthermore, quadratic trends with or without a transit model component produce comparable fits to the available data. Using extant WFC3 transit light curves for GJ 436b, we further validate the quadratic model component by achieving photon-limited model fit residuals and consistent transit depths over multiple epochs. We conclude that, when we fit for a quadratic trend, our new data contradict the prediction of a sub-Earth-sized planet orbiting GJ 436 with the size, period, and ephemeris posited from the Spitzer data by a margin of 3.1σ.

  5. Identification of Predictive Cis-Regulatory Elements Using a Discriminative Objective Function and a Dynamic Search Space.

    PubMed

    Karnik, Rahul; Beer, Michael A

    2015-01-01

    The generation of genomic binding or accessibility data from massively parallel sequencing technologies such as ChIP-seq and DNase-seq continues to accelerate. Yet state-of-the-art computational approaches for the identification of DNA binding motifs often yield motifs of weak predictive power. Here we present a novel computational algorithm called MotifSpec, designed to find predictive motifs, in contrast to over-represented sequence elements. The key distinguishing feature of this algorithm is that it uses a dynamic search space and a learned threshold to find discriminative motifs in combination with the modeling of motifs using a full PWM (position weight matrix) rather than k-mer words or regular expressions. We demonstrate that our approach finds motifs corresponding to known binding specificities in several mammalian ChIP-seq datasets, and that our PWMs classify the ChIP-seq signals with accuracy comparable to, or marginally better than motifs from the best existing algorithms. In other datasets, our algorithm identifies novel motifs where other methods fail. Finally, we apply this algorithm to detect motifs from expression datasets in C. elegans using a dynamic expression similarity metric rather than fixed expression clusters, and find novel predictive motifs. PMID:26465884

  6. One concept, three implementations of 3D pharmacophore-based virtual screening: distinct coverage of chemical search space.

    PubMed

    Spitzer, Gudrun M; Heiss, Mathias; Mangold, Martina; Markt, Patrick; Kirchmair, Johannes; Wolber, Gerhard; Liedl, Klaus R

    2010-07-26

    Feature-based pharmacophore modeling is a well-established concept to support early stage drug discovery, where large virtual databases are filtered for potential drug candidates. The concept is implemented in popular molecular modeling software, including Catalyst, Phase, and MOE. With these software tools we performed a comparative virtual screening campaign on HSP90 and FXIa, taken from the 'maximum unbiased validation' data set. Despite the straightforward concept that pharmacophores are based on, we observed an unexpectedly high degree of variation among the hit lists obtained. By harmonizing the pharmacophore feature definitions of the investigated approaches, the exclusion volume sphere settings, and the screening parameters, we have derived a rationale for the observed differences, providing insight on the strengths and weaknesses of these algorithms. Application of more than one of these software tools in parallel will result in a widened coverage of chemical space. This is not only rooted in the dissimilarity of feature definitions but also in different algorithmic search strategies. PMID:20583761

  7. Identification of Predictive Cis-Regulatory Elements Using a Discriminative Objective Function and a Dynamic Search Space

    PubMed Central

    Karnik, Rahul; Beer, Michael A.

    2015-01-01

    The generation of genomic binding or accessibility data from massively parallel sequencing technologies such as ChIP-seq and DNase-seq continues to accelerate. Yet state-of-the-art computational approaches for the identification of DNA binding motifs often yield motifs of weak predictive power. Here we present a novel computational algorithm called MotifSpec, designed to find predictive motifs, in contrast to over-represented sequence elements. The key distinguishing feature of this algorithm is that it uses a dynamic search space and a learned threshold to find discriminative motifs in combination with the modeling of motifs using a full PWM (position weight matrix) rather than k-mer words or regular expressions. We demonstrate that our approach finds motifs corresponding to known binding specificities in several mammalian ChIP-seq datasets, and that our PWMs classify the ChIP-seq signals with accuracy comparable to, or marginally better than motifs from the best existing algorithms. In other datasets, our algorithm identifies novel motifs where other methods fail. Finally, we apply this algorithm to detect motifs from expression datasets in C. elegans using a dynamic expression similarity metric rather than fixed expression clusters, and find novel predictive motifs. PMID:26465884

  8. 14 CFR § 1206.702 - Waiver or reduction of fees.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Waiver or reduction of fees. § 1206.702 Section § 1206.702 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION AVAILABILITY OF AGENCY RECORDS TO MEMBERS OF THE PUBLIC Search, Review, and Duplication Fees § 1206.702 Waiver...

  9. A Hubble Space Telescope/Cosmic Origins Spectrograph Search for Warm-hot Baryons in the Mrk 421 Sight Line

    NASA Astrophysics Data System (ADS)

    Danforth, Charles W.; Stocke, John T.; Keeney, Brian A.; Penton, Steven V.; Shull, J. Michael; Yao, Yangsen; Green, James C.

    2011-12-01

    Thermally broadened Lyα absorbers (BLAs) offer an alternate method to using highly ionized metal absorbers (O VI, O VII, etc.) to probe the warm-hot intergalactic medium (WHIM, T = 105-107 K). Until now, WHIM surveys via BLAs have been no less ambiguous than those via far-UV and X-ray metal-ion probes. Detecting these weak, broad features requires background sources with a well-characterized far-UV continuum and data of very high quality. However, a recent Hubble Space Telescope/Cosmic Origins Spectrograph (COS) observation of the z = 0.03 blazar Mrk 421 allows us to perform a metal-independent search for WHIM gas with unprecedented precision. The data have high signal-to-noise ratio (S/N ≈ 50 per ~20 km s-1 resolution element) and the smooth, power-law blazar spectrum allows a fully parametric continuum model. We analyze the Mrk 421 sight line for BLA absorbers, particularly for counterparts to the proposed O VII WHIM systems reported by Nicastro et al. based on Chandra/Low Energy Transmission Grating observations. We derive the Lyα profiles predicted by the X-ray observations. The S/N of the COS data is high (S/N ≈ 25 pixel-1), but much higher S/N can be obtained by binning the data to widths characteristic of the expected BLA profiles. With this technique, we are sensitive to WHIM gas over a large (N H, T) parameter range in the Mrk 421 sight line. We rule out the claimed Nicastro et al. O VII detections at their nominal temperatures (T ~ 1-2 × 106 K) and metallicities (Z = 0.1 Z ⊙) at >~ 2σ level. However, WHIM gas at higher temperatures and/or higher metallicities is consistent with our COS non-detections. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.

  10. HUBBLE SPACE TELESCOPE PROPER MOTION (HSTPROMO) CATALOGS OF GALACTIC GLOBULAR CLUSTERS. I. SAMPLE SELECTION, DATA REDUCTION, AND NGC 7078 RESULTS

    SciTech Connect

    Bellini, A.; Anderson, J.; Van der Marel, R. P.; Watkins, L. L.; King, I. R.; Bianchini, P.; Chanamé, J.; Chandar, R.; Cool, A. M.; Ferraro, F. R.; Massari, D.; Ford, H.

    2014-12-20

    We present the first study of high-precision internal proper motions (PMs) in a large sample of globular clusters, based on Hubble Space Telescope (HST) data obtained over the past decade with the ACS/WFC, ACS/HRC, and WFC3/UVIS instruments. We determine PMs for over 1.3 million stars in the central regions of 22 clusters, with a median number of ∼60,000 stars per cluster. These PMs have the potential to significantly advance our understanding of the internal kinematics of globular clusters by extending past line-of-sight (LOS) velocity measurements to two- or three-dimensional velocities, lower stellar masses, and larger sample sizes. We describe the reduction pipeline that we developed to derive homogeneous PMs from the very heterogeneous archival data. We demonstrate the quality of the measurements through extensive Monte Carlo simulations. We also discuss the PM errors introduced by various systematic effects and the techniques that we have developed to correct or remove them to the extent possible. We provide in electronic form the catalog for NGC 7078 (M 15), which consists of 77,837 stars in the central 2.'4. We validate the catalog by comparison with existing PM measurements and LOS velocities and use it to study the dependence of the velocity dispersion on radius, stellar magnitude (or mass) along the main sequence, and direction in the plane of the sky (radial or tangential). Subsequent papers in this series will explore a range of applications in globular-cluster science and will also present the PM catalogs for the other sample clusters.

  11. A MAGELLAN-IMACS-IFU SEARCH FOR DYNAMICAL DRIVERS OF NUCLEAR ACTIVITY. I. REDUCTION PIPELINE AND GALAXY CATALOG

    SciTech Connect

    Westoby, P. B.; Mundell, C. G.; Maciejewski, W.; Baldry, I. K.; Nagar, N. M.; Emsellem, E.; Roth, M. M.; Gerssen, J.

    2012-03-01

    Using the IMACS integral-field unit (IFU) on the 6.5 m Magellan telescope, we have designed the first statistically significant investigation of the two-dimensional distribution and kinematics of ionized gas and stars in the central kiloparsec regions of a well-matched sample of Seyfert and inactive control galaxies selected from the Sloan Digital Sky Survey. The goals of the project are to use the fine spatial sampling (0.2 arcsec pixel{sup -1}) and large wavelength coverage (4000-7000 A) of the IMACS-IFU to search for dynamical triggers of nuclear activity in the central region where active galactic nucleus (AGN) activity and dynamical timescales become comparable, to identify and assess the impact of AGN-driven outflows on the host galaxy and to provide a definitive sample of local galaxy kinematics for comparison with future three-dimensional kinematic studies of high-redshift systems. In this paper, we provide the first detailed description of the procedure to reduce and calibrate data from the IMACS-IFU in 'long mode' to obtain two-dimensional maps of the distribution and kinematics of ionized gas and stars. The sample selection criteria are presented, the observing strategy is described, and resulting maps of the sample galaxies are presented along with a description of the observed properties of each galaxy and the overall observed properties of the sample.

  12. Linking structure to function: The search for active sites in non-platinum group metal oxygen reduction reaction catalysts

    DOE PAGESBeta

    Holby, Edward F.; Zelenay, Piotr

    2016-05-17

    Atomic-scale structures of oxygen reduction reaction (ORR) active sites in non-platinum group metal (non-PGM) catalysts, made from pyrolysis of carbon, nitrogen, and transition-metal (TM) precursors have been the subject of continuing discussion in the fuel cell electrocatalysis research community. We found that quantum chemical modeling is a path forward for understanding of these materials and how they catalyze the ORR. Here, we demonstrate through literature examples of how such modeling can be used to better understand non-PGM ORR active site relative stability and activity and how such efforts can also aid in the interpretation of experimental signatures produced by thesemore » materials.« less

  13. The search for a subsurface ocean in Ganymede with Hubble Space Telescope observations of its auroral ovals

    NASA Astrophysics Data System (ADS)

    Saur, Joachim; Duling, Stefan; Roth, Lorenz; Jia, Xianzhe; Strobel, Darrell F.; Feldman, Paul D.; Christensen, Ulrich R.; Retherford, Kurt D.; McGrath, Melissa A.; Musacchio, Fabrizio; Wennmacher, Alexandre; Neubauer, Fritz M.; Simon, Sven; Hartkorn, Oliver

    2015-03-01

    We present a new approach to search for a subsurface ocean within Ganymede through observations and modeling of the dynamics of its auroral ovals. The locations of the auroral ovals oscillate due to Jupiter's time-varying magnetospheric field seen in the rest frame of Ganymede. If an electrically conductive ocean is present, the external time-varying magnetic field is reduced due to induction within the ocean and the oscillation amplitude of the ovals decreases. Hubble Space Telescope (HST) observations show that the locations of the ovals oscillate on average by 2.0° ±1.3°. Our model calculations predict a significantly stronger oscillation by 5.8° ± 1.3° without ocean compared to 2.2°±1.3° if an ocean is present. Because the ocean and the no-ocean hypotheses cannot be separated by simple visual inspection of individual HST images, we apply a statistical analysis including a Monte Carlo test to also address the uncertainty caused by the patchiness of observed emissions. The observations require a minimum electrical conductivity of 0.09 S/m for an ocean assumed to be located between 150 km and 250 km depth or alternatively a maximum depth of the top of the ocean at 330 km. Our analysis implies that Ganymede's dynamo possesses an outstandingly low quadrupole-to-dipole moment ratio. The new technique applied here is suited to probe the interior of other planetary bodies by monitoring their auroral response to time-varying magnetic fields.

  14. Space.

    ERIC Educational Resources Information Center

    Web Feet K-8, 2001

    2001-01-01

    This annotated subject guide to Web sites and additional resources focuses on space and astronomy. Specifies age levels for resources that include Web sites, CD-ROMS and software, videos, books, audios, and magazines; offers professional resources; and presents a relevant class activity. (LRW)

  15. Biochemical assessment of the hibernator skeletal muscle properties in search of a potential countermeasure against muscle atrophy in space microgravity

    NASA Astrophysics Data System (ADS)

    Lee, K.; Park, J. Y.; Gwag, T.; Yoo, W.; Choi, I.

    Mammalian skeletal muscle undergoes significant loss of mass and tension capacity during spaceflight or hindlimb suspension This is contrasted by observed features of hibernators in that muscle mass and contractility remain fairly unchanged during a prolonged period of dormancy In an effort of finding potential countermeasure against muscle atrophy in space microgravity we thereby investigated the biochemical properties of the pectoral muscle in a winter-hibernating bat Murina leucogaster Two-dimensional electrophoresis on overall muscle proteins and western blot analysis on heat shock proteins HSP 60 kD 70 kD and 90 kD were conducted to compare levels of myofiber proteins and the stress responsive chaperone molecules in winter-hibernation WH versus summer-active bats SA No seasonal difference was found in the ratio of muscle mass to body mass for the pectoral muscles confirming similar results in previous reports Among more than thirty proteins identified only 14 of the proteins showed significant reduction in the level for WH compared to SA The level of HSP60 and HSP90 in WH were 63 and 71 that in SA respectively P quad 0 05 whereas that of HSP70 was not different between the two groups However when the WH were forced to arouse for 40 min from hibernation the level of HSP70 increased 1 4-fold and 1 51-fold that of WH and SA respectively while the level of HSP90 increased 1 57-fold that of WH These results suggest that the levels of many key contractile and regulatory proteins were retained during

  16. Nonlinear dimensionality reduction of CT histogram based feature space for predicting recurrence-free survival in non-small-cell lung cancer

    NASA Astrophysics Data System (ADS)

    Kawata, Y.; Niki, N.; Ohmatsu, H.; Aokage, K.; Kusumoto, M.; Tsuchida, T.; Eguchi, K.; Kaneko, M.

    2015-03-01

    Advantages of CT scanners with high resolution have allowed the improved detection of lung cancers. In the recent release of positive results from the National Lung Screening Trial (NLST) in the US showing that CT screening does in fact have a positive impact on the reduction of lung cancer related mortality. While this study does show the efficacy of CT based screening, physicians often face the problems of deciding appropriate management strategies for maximizing patient survival and for preserving lung function. Several key manifold-learning approaches efficiently reveal intrinsic low-dimensional structures latent in high-dimensional data spaces. This study was performed to investigate whether the dimensionality reduction can identify embedded structures from the CT histogram feature of non-small-cell lung cancer (NSCLC) space to improve the performance in predicting the likelihood of RFS for patients with NSCLC.

  17. A HUBBLE SPACE TELESCOPE/COSMIC ORIGINS SPECTROGRAPH SEARCH FOR WARM-HOT BARYONS IN THE Mrk 421 SIGHT LINE

    SciTech Connect

    Danforth, Charles W.; Stocke, John T.; Keeney, Brian A.; Penton, Steven V.; Shull, J. Michael; Yao Yangsen; Green, James C.

    2011-12-10

    Thermally broadened Ly{alpha} absorbers (BLAs) offer an alternate method to using highly ionized metal absorbers (O VI, O VII, etc.) to probe the warm-hot intergalactic medium (WHIM, T = 10{sup 5}-10{sup 7} K). Until now, WHIM surveys via BLAs have been no less ambiguous than those via far-UV and X-ray metal-ion probes. Detecting these weak, broad features requires background sources with a well-characterized far-UV continuum and data of very high quality. However, a recent Hubble Space Telescope/Cosmic Origins Spectrograph (COS) observation of the z = 0.03 blazar Mrk 421 allows us to perform a metal-independent search for WHIM gas with unprecedented precision. The data have high signal-to-noise ratio (S/N Almost-Equal-To 50 per {approx}20 km s{sup -1} resolution element) and the smooth, power-law blazar spectrum allows a fully parametric continuum model. We analyze the Mrk 421 sight line for BLA absorbers, particularly for counterparts to the proposed O VII WHIM systems reported by Nicastro et al. based on Chandra/Low Energy Transmission Grating observations. We derive the Ly{alpha} profiles predicted by the X-ray observations. The S/N of the COS data is high (S/N Almost-Equal-To 25 pixel{sup -1}), but much higher S/N can be obtained by binning the data to widths characteristic of the expected BLA profiles. With this technique, we are sensitive to WHIM gas over a large (N{sub H}, T) parameter range in the Mrk 421 sight line. We rule out the claimed Nicastro et al. O VII detections at their nominal temperatures (T {approx} 1-2 Multiplication-Sign 10{sup 6} K) and metallicities (Z = 0.1 Z{sub Sun }) at {approx}> 2{sigma} level. However, WHIM gas at higher temperatures and/or higher metallicities is consistent with our COS non-detections.

  18. Using the RDP Classifier to Predict Taxonomic Novelty and Reduce the Search Space for Finding Novel Organisms

    PubMed Central

    Lan, Yemin; Wang, Qiong; Cole, James R.; Rosen, Gail L.

    2012-01-01

    Background Currently, the naïve Bayesian classifier provided by the Ribosomal Database Project (RDP) is one of the most widely used tools to classify 16S rRNA sequences, mainly collected from environmental samples. We show that RDP has 97+% assignment accuracy and is fast for 250 bp and longer reads when the read originates from a taxon known to the database. Because most environmental samples will contain organisms from taxa whose 16S rRNA genes have not been previously sequenced, we aim to benchmark how well the RDP classifier and other competing methods can discriminate these novel taxa from known taxa. Principal Findings Because each fragment is assigned a score (containing likelihood or confidence information such as the boostrap score in the RDP classifier), we “train” a threshold to discriminate between novel and known organisms and observe its performance on a test set. The threshold that we determine tends to be conservative (low sensitivity but high specificity) for naïve Bayesian methods. Nonetheless, our method performs better with the RDP classifier than the other methods tested, measured by the f-measure and the area-under-the-curve on the receiver operating characteristic of the test set. By constraining the database to well-represented genera, sensitivity improves 3–15%. Finally, we show that the detector is a good predictor to determine novel abundant taxa (especially for finer levels of taxonomy where novelty is more likely to be present). Conclusions We conclude that selecting a read-length appropriate RDP bootstrap score can significantly reduce the search space for identifying novel genera and higher levels in taxonomy. In addition, having a well-represented database significantly improves performance while having genera that are “highly” similar does not make a significant improvement. On a real dataset from an Amazon Terra Preta soil sample, we show that the detector can predict (or correlates to) whether novel sequences will be

  19. Effects of spot size and spot spacing on lateral penumbra reduction when using a dynamic collimation system for spot scanning proton therapy

    NASA Astrophysics Data System (ADS)

    Hyer, Daniel E.; Hill, Patrick M.; Wang, Dongxu; Smith, Blake R.; Flynn, Ryan T.

    2014-11-01

    The purpose of this work was to investigate the reduction in lateral dose penumbra that can be achieved when using a dynamic collimation system (DCS) for spot scanning proton therapy as a function of two beam parameters: spot size and spot spacing. This is an important investigation as both values impact the achievable dose distribution and a wide range of values currently exist depending on delivery hardware. Treatment plans were created both with and without the DCS for in-air spot sizes (σair) of 3, 5, 7, and 9 mm as well as spot spacing intervals of 2, 4, 6 and 8 mm. Compared to un-collimated treatment plans, the plans created with the DCS yielded a reduction in the mean dose to normal tissue surrounding the target of 26.2-40.6% for spot sizes of 3-9 mm, respectively. Increasing the spot spacing resulted in a decrease in the time penalty associated with using the DCS that was approximately proportional to the reduction in the number of rows in the raster delivery pattern. We conclude that dose distributions achievable when using the DCS are comparable to those only attainable with much smaller initial spot sizes, suggesting that the goal of improving high dose conformity may be achieved by either utilizing a DCS or by improving beam line optics.

  20. Effects of spot size and spot spacing on lateral penumbra reduction when using a dynamic collimation system for spot scanning proton therapy.

    PubMed

    Hyer, Daniel E; Hill, Patrick M; Wang, Dongxu; Smith, Blake R; Flynn, Ryan T

    2014-11-21

    The purpose of this work was to investigate the reduction in lateral dose penumbra that can be achieved when using a dynamic collimation system (DCS) for spot scanning proton therapy as a function of two beam parameters: spot size and spot spacing. This is an important investigation as both values impact the achievable dose distribution and a wide range of values currently exist depending on delivery hardware. Treatment plans were created both with and without the DCS for in-air spot sizes (σair) of 3, 5, 7, and 9 mm as well as spot spacing intervals of 2, 4, 6 and 8 mm. Compared to un-collimated treatment plans, the plans created with the DCS yielded a reduction in the mean dose to normal tissue surrounding the target of 26.2-40.6% for spot sizes of 3-9 mm, respectively. Increasing the spot spacing resulted in a decrease in the time penalty associated with using the DCS that was approximately proportional to the reduction in the number of rows in the raster delivery pattern. We conclude that dose distributions achievable when using the DCS are comparable to those only attainable with much smaller initial spot sizes, suggesting that the goal of improving high dose conformity may be achieved by either utilizing a DCS or by improving beam line optics. PMID:25330783

  1. State-space representation of Li-ion battery porous electrode impedance model with balanced model reduction

    NASA Astrophysics Data System (ADS)

    Jun, Myungsoo; Smith, Kandler; Graf, Peter

    2015-01-01

    This paper presents an approximate time-domain solution for physics-based electrochemical lithium-ion cell battery models. The time-domain solution is represented in state-space form and can be easily used for the design of a state estimator or controller. It uses an interconnection-of-system approach to derive a state-space representation of a battery impedance model and provides a reduced order model based via the balanced truncation method. Simulation results are also provided to show the performance of the proposed model in the frequency domain.

  2. A hybrid color space for skin detection using genetic algorithm heuristic search and principal component analysis technique.

    PubMed

    Maktabdar Oghaz, Mahdi; Maarof, Mohd Aizaini; Zainal, Anazida; Rohani, Mohd Foad; Yaghoubyan, S Hadi

    2015-01-01

    Color is one of the most prominent features of an image and used in many skin and face detection applications. Color space transformation is widely used by researchers to improve face and skin detection performance. Despite the substantial research efforts in this area, choosing a proper color space in terms of skin and face classification performance which can address issues like illumination variations, various camera characteristics and diversity in skin color tones has remained an open issue. This research proposes a new three-dimensional hybrid color space termed SKN by employing the Genetic Algorithm heuristic and Principal Component Analysis to find the optimal representation of human skin color in over seventeen existing color spaces. Genetic Algorithm heuristic is used to find the optimal color component combination setup in terms of skin detection accuracy while the Principal Component Analysis projects the optimal Genetic Algorithm solution to a less complex dimension. Pixel wise skin detection was used to evaluate the performance of the proposed color space. We have employed four classifiers including Random Forest, Naïve Bayes, Support Vector Machine and Multilayer Perceptron in order to generate the human skin color predictive model. The proposed color space was compared to some existing color spaces and shows superior results in terms of pixel-wise skin detection accuracy. Experimental results show that by using Random Forest classifier, the proposed SKN color space obtained an average F-score and True Positive Rate of 0.953 and False Positive Rate of 0.0482 which outperformed the existing color spaces in terms of pixel wise skin detection accuracy. The results also indicate that among the classifiers used in this study, Random Forest is the most suitable classifier for pixel wise skin detection applications. PMID:26267377

  3. A Hybrid Color Space for Skin Detection Using Genetic Algorithm Heuristic Search and Principal Component Analysis Technique

    PubMed Central

    2015-01-01

    Color is one of the most prominent features of an image and used in many skin and face detection applications. Color space transformation is widely used by researchers to improve face and skin detection performance. Despite the substantial research efforts in this area, choosing a proper color space in terms of skin and face classification performance which can address issues like illumination variations, various camera characteristics and diversity in skin color tones has remained an open issue. This research proposes a new three-dimensional hybrid color space termed SKN by employing the Genetic Algorithm heuristic and Principal Component Analysis to find the optimal representation of human skin color in over seventeen existing color spaces. Genetic Algorithm heuristic is used to find the optimal color component combination setup in terms of skin detection accuracy while the Principal Component Analysis projects the optimal Genetic Algorithm solution to a less complex dimension. Pixel wise skin detection was used to evaluate the performance of the proposed color space. We have employed four classifiers including Random Forest, Naïve Bayes, Support Vector Machine and Multilayer Perceptron in order to generate the human skin color predictive model. The proposed color space was compared to some existing color spaces and shows superior results in terms of pixel-wise skin detection accuracy. Experimental results show that by using Random Forest classifier, the proposed SKN color space obtained an average F-score and True Positive Rate of 0.953 and False Positive Rate of 0.0482 which outperformed the existing color spaces in terms of pixel wise skin detection accuracy. The results also indicate that among the classifiers used in this study, Random Forest is the most suitable classifier for pixel wise skin detection applications. PMID:26267377

  4. Enabling and Enhancing Space Mission Success and Reduction of Risk through the Application of an Integrated Data Architecture

    NASA Technical Reports Server (NTRS)

    Brummett, Robert C.

    2008-01-01

    The engineering phases of design, development, test, and evaluation (DDT and E) and subsequent planning, preparation, and operation (Ops) of space vehicles in a complex and distributed environment requires massive and continuous flows of information across the enterprise and across temporal stages of the vehicle lifecycle. The resulting capabilities at each subsequent stage depend in part on the capture, preparation, storage, and subsequent provision of information from prior stages. The United States National Aeronautics and Space Administration (NASA) is currently designing a fleet of new vehicles that will replace the Space Shuttle and expand space operations and exploration capabilities. This includes the 2 stage human rated lift vehicle Ares 1 and its associated crew vehicle the Orion, and a service module; the heavy lift cargo vehicle, Ares 5, and an associated cargo stage known as the Earth Departure Stage; and a Lunar Lander vehicle that contains a descent stage, and ascent stage, and a habitation module. A variety of concurrent assorted ground operations infrastructure including software and facilities are also being developed, assorted technology and assembly designs and development for equipment such as EVA suits, life support systems, command and control technologies are also in the pipeline. The development is occurring in a distributed manner, with project deliverables being contributed by a large and diverse assortment of vendors and most space faring nations. Critical information about all of the components, software, and procedures must be shared during the DDT and E phases and then made readily available to the mission operations staff for access during the planning, preparation, and operations phases, and also need to be readily available for system to system interactions. The Constellation Data Systems Project (CxDS) is identifying the needs, and designing and deploying systems and processes to support these needs. This paper details the steps

  5. Key issues for the strategic-offensive-force reduction portion of the nuclear and space talks in Geneva. Interim report

    SciTech Connect

    Warner, E.L.; Kent, G.A.; DeValk, R.J.

    1985-12-01

    This note discusses approaches for the limitation and reduction of U.S. and Soviet strategic attack forces. It identifies three national security objectives that the United States and, arguably, the Soviet Union seek to obtain through a combination of strategic nuclear force deployments, arms control, and diplomacy: credible deterrence, strategic, crisis stability, and essential equivalence. It defines three measures that can be controlled to constrain the destructive capacity of intercontinental strategic attack forces: the amount of ballistic missile throwweight, the number of ballistic missile RVs, and the amount of bomber gross takeoff weight. It then considers an alternative approach, a weighted composite measure that yields a smaller initial difference between U.S. and Soviet ballistic missile forces than the pure throwweight approach, thus providing better prospects for successful compromise in negotiation. It concludes that the United States cannot reasonably expect to gain any treaty significant reductions in Soviet ballistic missile capabilities without being prepared to accept considerable constraints on the growth of the U.S. bomber force weapon-carrying potential.

  6. SEARCHING FOR TROJAN ASTEROIDS IN THE HD 209458 SYSTEM: SPACE-BASED MOST PHOTOMETRY AND DYNAMICAL MODELING

    SciTech Connect

    Moldovan, Reka; Matthews, Jaymie M.; Gladman, Brett; Bottke, William F.; Vokrouhlicky, David

    2010-06-10

    We have searched Microvariability and Oscillations of Stars (MOST) satellite photometry obtained in 2004, 2005, and 2007 of the solar-type star HD 209458 for Trojan asteroid swarms dynamically coupled with the system's transiting 'hot Jupiter' HD 209458b. Observations of the presence and nature of asteroids around other stars would provide unique constraints on migration models of exoplanetary systems. Our results set an upper limit on the optical depth of Trojans in the HD 209458 system that can be used to guide current and future searches of similar systems by upcoming missions. Using cross-correlation methods with artificial signals implanted in the data, we find that our detection limit corresponds to a relative Trojan transit depth of 1 x10{sup -4}, equivalent to {approx}1 lunar mass of asteroids, assuming power-law Trojan size distributions similar to Jupiter's Trojans in our solar system. We confirm with dynamical interpretations that some asteroids could have migrated inward with the planet to its current orbit at 0.045 AU, and that the Yarkovsky effect is ineffective at eliminating objects of >1 m in size. However, using numerical models of collisional evolution we find that, due to high relative speeds in this confined Trojan environment, collisions destroy the vast majority of the asteroids in <10 Myr. Our modeling indicates that the best candidates to search for exoTrojan swarms in 1:1 mean resonance orbits with 'hot Jupiters' are young systems (ages of about 1 Myr or less). Years of Kepler satellite monitoring of such a system could detect an asteroid swarm with a predicted transit depth of 3 x 10{sup -7}.

  7. CO2 Compressor Requirements for Integration of Space Station Carbon Dioxide Removal and Carbon Dioxide Reduction Assemblies

    NASA Technical Reports Server (NTRS)

    Jeng, Frank F.; Lewis, John F.; Graf, John; LaFuse, Sharon; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    This paper describes the analysis on integration requirements, CO2 compressor in particular, for integration of Carbon Dioxide Removal Assembly (CDRA) and CO2 Reduction Assembly (CRA) as a part of the Node 3 project previously conducted at JSC/NASA. A system analysis on the volume and operation pressure range of the CO2 accumulator was conducted. The hardware and operational configurations of the CO2 compressor were developed. The performance and interface requirements of the compressor were specified. An existing Four-Bed Molecular Sieve CO2 removal computer model was modified into a CDRA model and used in analyzing the requirements of the CDRA CO2 compressor. This CDRA model was also used in analyzing CDRA operation parameters that dictate CO2 pump sizing. Strategy for the pump activation was also analyzed.

  8. Directed searches for continuous gravitational waves from binary systems: Parameter-space metrics and optimal Scorpius X-1 sensitivity

    NASA Astrophysics Data System (ADS)

    Leaci, Paola; Prix, Reinhard

    2015-05-01

    We derive simple analytic expressions for the (coherent and semicoherent) phase metrics of continuous-wave sources in low-eccentricity binary systems for the two regimes of long and short segments compared to the orbital period. The resulting expressions correct and extend previous results found in the literature. We present results of extensive Monte Carlo studies comparing metric mismatch predictions against the measured loss of detection statistics for binary parameter offsets. The agreement is generally found to be within ˜10 %- 30 % . For an application of the metric template expressions, we estimate the optimal achievable sensitivity of an Einstein@Home directed search for Scorpius X-1, under the assumption of sufficiently small spin wandering. We find that such a search, using data from the upcoming advanced detectors, would be able to beat the torque-balance level [R. V. Wagoner, Astrophys. J. 278, 345 (1984); L. Bildsten, Astrophys. J. 501, L89 (1998).] up to a frequency of ˜500 - 600 Hz , if orbital eccentricity is well constrained, and up to a frequency of ˜160 - 200 Hz for more conservative assumptions about the uncertainty on orbital eccentricity.

  9. Methods for data reduction and loads analysis of Space Shuttle Solid Rocket Booster model water impact tests

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The methodology used to predict full scale space shuttle solid rocket booster (SRB) water impact loads from scale model test data is described. Tests conducted included 12.5 inch and 120 inch diameter models of the SRB. Geometry and mass characteristics of the models were varied in each test series to reflect the current SRB baseline configuration. Nose first and tail first water entry modes were investigated with full-scale initial impact vertical velocities of 40 to 120 ft/sec, horizontal velocities of 0 to 60 ft/sec., and off-vertical angles of 0 to plus or minus 30 degrees. The test program included a series of tests with scaled atmospheric pressure.

  10. A comprehensive study over the recent important reduction in SO2 and NO2 emissions from the power plants located in S-E Europe using space observations

    NASA Astrophysics Data System (ADS)

    Bocǎnealǎ, Corina; Constantin, Daniel-Eduard; Theys, Nicolas; Merlaud, Alexis; Van Roozendael, Michel

    2016-04-01

    The aim of this study is to investigate the recent important reduction of atmospheric SO2 and NO2 emissions from several power plants located in S-E Europe during 2005-2014 using space observations. The study is focused over three large power plants which are located in Romania and Bulgaria: Turceni (44.66°N, 23.38°E), Rovinari (44.9°N, 23.15°E) and Stara Zagora (42.43°N, 25.65°E). The space observations used in this work are based on OMI (Ozone Monitoring Instrument) and GOME-2 (Global Ozone Monitoring Experiment Measurements) measurements. The results obtained using data from satellites are compared with in-situ observations and calculated emissions. The OMI and GOME-2 observed SO2 and NO2 content is well correlated with the in-situ data and calculated SO2 and NOx emissions. This study investigates the potential of using satellite observations as an instrument to check quality air as a standard procedure by governmental and non-governmental institutions. To this aim, we compared the emissions calculated from ground and space with the European Directive 2001/80/EC which refers to the limitation of emissions of certain pollutants by large combustion plants.