Mostrando recursos 1 - 20 de 191.998

  1. Development of an information fusion system for engine diagnostics and health management

    Allan J Volponi; Tom Brotherton
    Aircraft gas-turbine engine data is available from a variety of sources including on-board sensor measurements, maintenance histories, and component models. An ultimate goal of Propulsion Health Management (PHM) is to maximize the amount of meaningful information that can be extracted from disparate data sources to obtain comprehensive diagnostic and prognostic knowledge regarding the health of the engine. Data Fusion is the integration of data or information from multiple sources, to achieve improved accuracy and more specific inferences than can be obtained from the use of a single sensor alone. The basic tenet underlying the data/information fusion concept is to leverage...

  2. Locating Mobile Nodes with EASE: Learning Efficient Routes from Encounter Histories Alone

    Matthias Grossglauser; Martin Vetterli
    Abstract—Routing in large-scale mobile ad hoc networks is challenging because all the nodes are potentially moving. Geographic routing can partially alleviate this problem, as nodes can make local routing decisions based solely on the destinations ’ geographic coordinates. However, geographic routing still requires an efficient location service, i.e., a distributed database recording the location of every destination node. Devising efficient, scalable, and robust location services has received considerable attention in recent years. The main purpose of this paper is to show that node mobility can be exploited to disseminate destination location information without incurring any communication overhead. We achieve this...

  3. Abstraction Mechanisms in Hypertext

    Pankaj K. Garg
    Abstraction is the means by which information can be stored and retrieved from an information structure at different levels of detail and from different perspectives. As such, abstraction mech-anisms in hypertext are interesting to study and, evaluate. In this paper we study the abstraction mechanisms in hypertext born a theoretical perspective. Abstractions then become various first-order logic formulae. Specifically we consider abstractions: sets, sequences, aggregations, generalizations, revisions, and information structures. Interesting results of this work are the definition of level of generality of a hypertext node, the demonstration of revision histories as a partial order, and the notion of compatible-similar...

  4. Keywords: Text processing, text formatting, UNIX.

    Abstract: In a software development project of any appreciable size, the production of usable, accurate documentation may well consume more effort than the production of the software itself. Several years of experience on many Programmer's Workbench projects have shown that document preparation should not be separated from software development and that the combination of a flexible operating system, a powerful command language, and good text processing facilities permits quick and convenient production of many kinds of documentation which might be oth-erwise unobtainable, impractical, or very expensive. Our basic approach has been to develop techniques for effective combina-tion of existing UNIX...

  5. Minimum Recombination Histories by Branch and Bound

    Rune B. Lyngsø; Yun S. Song
    Abstract. Recombination plays an important role in creating genetic diversity within species, and inferring past recombination events is central to many problems in genetics. Given a set M of sampled sequences, finding an evolutionary history for M with the minimum number of recombination events is a computationally very challenging problem. In this paper, we present a novel branch and bound algorithm for tackling that problem. Our method is shown to be far more efficient than the only preexisting exact method, described in [1]. Our software implementing the algorithm discussed in this paper is publicly available. 1

  6. Extracting change-patterns from cvs repositories

    Salah Bouktif; Yann-gaël Guéhéneuc; Giuliano Antoniol
    Often, the only sources of information about the evolution of software systems are the systems themselves and their histories. Version control repositories contain information on several thousand of files and on millions of changes. We propose an approach based on dynamic time warping to discover change-patterns, which, for example, describe files that change together almost all the time. We define the Synchrony changepattern to answer the question: given a software system and one file under modification, what others files must be changed? We have applied our approach on PADL, a software system developed in Java, and on Mozilla. Interesting results...

  7. The Serializability of Concurrent Database Updates

    Christos H. Papadimitriou
    ABSTRACT A sequence of interleaved user transactions in a database system may not be ser:ahzable, t e, equivalent to some sequential execution of the individual transactions Using a simple transaction model, it ~s shown that recognizing the transaction histories that are serlahzable is an NP-complete problem. Several efficiently recognizable subclasses of the class of senahzable histories are therefore introduced; most of these subclasses correspond to senahzabdity principles existing in the hterature and used in practice Two new principles that subsume all previously known ones are also proposed Necessary and sufficient conditions are given for a class of histories to be...

  8. Experiments in UNIX command prediction

    Brian D. Davison; Haym Hirsh
    A good user interface is central to the success of most products. Our research is concerned with improving an interface by making it adaptive |changing over time as it learns more about the user. In this paper we consider the task of modifying a UNIX shell to learn to predict the next command executed as one sample adaptive user interface. To this end, we have collected command histories (some extensive) from 77 people, and have calculated the predictive accuracy for each of ve methods over this dataset. The algorithm with the highest performance produces an average online predictive accuracy of...

  9. A Fast Texture Synthesis Technique using Spatial Neighborhood

    Muath Sabha; Philip Dutré; Muath Sabha; Philip Dutré; Muath Sabha; Philip Dutré
    In this technical report, we present a texture synthesis technique that stores all possible histories in memory structure acting as a Finite State Machine. The histories, which are the most probable spatial neighborhood for each pixel or patch, are stored in each state of the FSM. After constructing that structure, the synthesis goes very fast and smooth in a raster scan order. We found that our technique works well for a wide variety of textures, ranging from stochastic to regular structured textures, including near-regular textures. We show that our technique is faster, and gives better results than previous pixel- or...

  10. Search histories for user support in user interfaces

    Anita Komlodi; Dagobert Soergel
    The authors describe user interface tools based on search histories to support legal information seekers. The design of the tools was informed by the results of a user study (Komlodi, 2002a) that examined the use of human memory, external memory aids, and search histories in legal information seeking and derived interface design recommendations for information storage and retrieval systems. The data collected were analyzed to identify potential task areas where search histories can support information seeking and use. The results show that many information-seeking tasks can take advantage of automatically and manually recorded history information. These findings encouraged the design...

  11. Calibration of time history simulation methods

    Gail M. Atkinson; Paul Somerville; Gail M. Atkinson; Paul G. Somerville
    Abstract Ground-motion time histories for use in engineering analyses of structures in eastern North America re often simulated from seismological models, owing to the paucity of real recordings in the magnitude and distance ranges of interest. Two simulation methods have been widely used in recent years: the stochastic method and the ray-theory method. In the stochastic method, as im-plemented in this study, ground motion is treated as filtered Gaussian noise whose underlying spectrum is determined from an empirical region-specific seismological model of the source and propagation processes. In the ray-theory method, as implemented in this study, the ground motions are...

  12. PEOPLE OF COLOR IN ALLIANCE From Theory to Practice

    Renee Miyuki Okamura; Renee Miyuki Okamura; Phillip Clay; Miyuki Okamura
    This thesis examines why and how people of color form alliances across racial lines. Through books, articles, interviews and one case study, I have found that alliances are an important strategy in community development. By joining together in alliance, people of color pool their human and economic resources to achieve goals they would have difficulty reaching alone. In the process of building these alliances, people of color create and model pluralistic institutions. As they struggle towards their goals, allies develop mutual respect and understanding. They institutionalize their diversity by including and valuing a broad range of cultures, histories, experiences, and...

  13. Better Outcome of Schizophrenia in India: A Natural Selection Against

    Severe Forms; Jagadisha Thirthalli; Sanjeev Jain
    Regional variations are observed in outcome of schizophre-nia, but reasons remain unclear. Outcome of schizophrenia is reported to be better in India. In this report based on cen-sus data, we highlight substantially greater mortality ob-served among the mentally ill than among the general population during famines in India in the 19th century. A possible selection against the most severe forms of schizophrenia could account for greater occurrence of better-outcome phenotypes. Population histories and en-vironmental influences, including epigenetics, need to be considered to further investigate differences between schizophrenia phenotypes.

  14. Current Views on the Etiology of Schizophrenia

    Rosemary Creed Lukton
    Social workers have traditionally held to psy-chological and sociological explanations of the causes of schizophrenia. But recent research is rapidly uncovering evidence for genetic and biochemical sources of the disorder. This may well prompt a reorientation of current treat-ment modalities. IN A RECENT experiment, eight psychologically sound "pseudo-patients " presented themselves to psychiatrists at twelve psychiatric hospitals. Feigning symptoms and pre-senting false case histories, they were able to have them-selves admitted to these hospitals with a diagnosis of schizophrenia. Once admitted, they behaved normally and cooperatively, but in no instance did hospital personnel question or alter the original diagnosis on...

  15. International Outsourcing, the Nature of Tasks, and Occupational Stability – Empirical Evidence for Germany,” Ruhr Economic Papers No

    Daniel Baumgarten
    Preliminary draft. Please do not cite without permission! Using a large administrative data set of individual employment histories in Ger-many, this paper studies how occupational stability is affected by the international fragmentation of production processes. Moreover, a rich data set on tasks performed in occupations is used to better characterize the sources of worker vulnerability. The impact of both international material outsourcing (in the manufacturing sector) and international service outsourcing (in the service sector) on occupational stability is found to vary with the intensity of non-routine and interactive tasks of the occupa-tion. Stability is the less negatively affected the higher...

  16. Brief Communication 257 Vet. Pathol. 21: 257-258 (1984) Spontaneous Uterine Tumors in Three Cats

    S. Papparella; F. Roperto
    It is uncommon to find uterine tumors in domestic ani-mals. Those with highest incidence are leiomyomas (bitch, cow), carcinoma (cow) and adenocarcinoma in the rab-and include fibroma,'.2 uncommon reports of adenocarcinoma*. ' I. l6 and a mixed mesodermal tumor: We report three cat uterine tumors brought to us during a five-year period. No clinical histories were available because only the uteri were submitted after hysterectomy. All tumors were fixed in 10 % saline formalin; selected tissues were embedded in paraffin, sectioned at 6 pm, and stained with hematoxylin and eosin, Verhoeff s-van Gieson's, and Gomo-ri's stains. Cat 1 was an...

  17. METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 34A, SEPTEMBER 2003—1941 The Importance of Viscoplastic Strain Rate in the Formation of Center Cracks during the Start-Up Phase of Direct-Chill Cast Aluminum

    Extrusion Ingots; S. Benum; D. Mortensen; H. G. Fjær; J. -m. Drezet
    A comparison of experimental observations and computer simulations shows that trends in the occur-rence and severity of center cracks in direct-chill (DC) cast ingots due to different initial casting speed histories may best be explained by the changes in viscoplastic strain rate close to the center of the base of the ingot. The thermomechanical histories of five ingots were simulated and correlations between stresses, strains, strain rates, and liquid pressure drops due to feeding restrictions were considered. I.

  18. NOTES AND ISSUES The Reliability of Retrospective Unemployment History Data

    Shirley Dex; Andrew Mcculloch
    This paper sets out to examine the reliability of data on men’s and women’s past experiences of unemployment spells which has been gained by asking individuals to recall these spells and the dates of their occur-rence. Surveys seek individuals ’ history data either to gain information about the initial conditions of respondents, or to examine these histories in their own right. It is much less expensive to collect data about individuals ’ histories by asking them to recall their experiences than it is to collect the same data from a panel survey over many years. However, important questions arise concerning...

  19. Yersinia Pestis: New Evidence for an Old Infection

    Kirsten Bos; Philip Stevens; Kay Nieselt; Johannes Krause; Kirsten I. Bos; Philip Stevens; Kay Nieselt; Hendrik N. Poinar; Sharon N. Dewitte; Johannes Krause
    The successful reconstruction of an ancient bacterial genome from archaeological material presents an important methodological advancement for infectious disease research. The reliability of evolutionary histories inferred by the incorporation of ancient data, however, are highly contingent upon the level of genetic diversity represented in modern genomic sequences that are publicly accessible, and the paucity of available complete genomes restricts the level of phylogenetic resolution that can be obtained. Here we add to our original analysis of the Yersinia pestis strain implicated in the Black Death by consolidating our dataset for 18 modern genomes with single nucleotide polymorphism (SNP) data for...

  20. An Assessment of the Extent of Child Maltreatment Using Administrative Databases. Assessment

    Steven M. Banks
    This study examined the extent of violence toward children and factors associated with child maltreatment in Florida using a cohort of children (N = 499,330) who were adjudged to be victims of maltreatment between July 1, 1996, and June 30, 2003. To assess the extent of maltreatment, five indicators were proposed and examined. Multivariate analyses found that prior referral, having more than one type of maltreatment during an initial incident, and caregiver absence best predicted the recurrence of maltreatment. Caregivers ’ alcohol and substance use were strong predictors of neglect and threatened harm but not of abuse. Finally, multilevel analyses...

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