305 research outputs found

    Hydraulic Modeling of Glacial Dam-Break Floods on the West Branch of the Susquehanna River, Pennsylvania

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    This study investigates the potential hydraulic conditions of catastrophic floods in the West Branch of the Susquehanna River (West Branch) during the middle to late Pleistocene period and the influence of these paleofloods on the current river bed form. The current channel bed form is characterized using sonar bathymetry data collection techniques. The paleofloods are hypothesized based on published geological evidence of early Pleistocene glacial Lake Lesley in the West Branch Valley, which was formed by a glacial ice dam that potentially failed during mild climate cycles in the Pleistocene period. A one-dimensional, steady hydraulic model is developed to simulate estimates of paleoflood peak discharges and the modern 100 year return period peak discharge. The computed water-surface profiles, shear stresses, and flood inundation maps could explain the erosional and depositional features identified by other researchers as being formed during the Pleistocene and could explain features revealed by the bathymetry data. Therefore, the hydraulic modeling results support previously inferred hypotheses of the occurrence of glacial dam-break floods on the West Branch of the Susquehanna River. The differences that are evident between the paleoflood simulations and the simulation of the modern 100 year peak discharge are attributable to valley constrictions that cause substantial backwater effects for the larger paleoflood discharges but not for the lower modern flood discharge volume. The ability to simulate potential paleofloods in the West Branch of the Susquehanna River complements the paleostage indicator work done by other researchers and enables innovative analysis of glaciofluvial processes and their effect on the current river bed form

    Post-Flood Cleanup Alternatives along Stream Corridors in Central Pennsylvania Helping Resolve River and Land Use Conflicts in an Economically and Ecologically Sustainable Manner

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    Report on managing river corridors of Central Pennsylvania in an economically and ecologically sustainable manner. Fluvial geomorphologists and civil engineers from Bucknell University present results of research and analysis of the impact of floods on Central Pennsylvania streams, bridges, dams, and roads. Ten sections cover 1. Key Concepts for Managing River Corridors in a Sustainable Manner; 2. Options for Managing the Conflict between Nature and Man; 3. The Physical Imperatives of River Systems; 4. Dynamic Equilibrium of Streams and Anticipating Adjustments in the Future; 5. The Conflict: Today’s Accounting; 6. Cost-Benefit Analysis; 7. Short vs. Long Term Solutions: A Choice of Management Scenarios; 8. “Stream-Cleaning” – allow gravel or “do nothing”? 9. Informing the Alternative Selection Process; 10. Managing Sustainably. The report focuses on the long term benefits of a geomorphic corridor management approach which can benefit both property owners and riparian ecosystems. The largest challenge is not in conducting the scientific analyses to determine the river’s slope and planform requirements, but rather in how to redefine the relationship of public and private investments with fluvial dynamics in an equitable manner over time within a watershed. The larger short term costs associated with using a geomorphic-based approach, where land conversion is necessary, become more acceptable and economically justifiable where channelization projects have failed repeatedly or in post flood remediation where major erosion, property damage, and channel avulsions have occurred. A passive geomorphic approach may be the most desirable alternative due to its lower maintenance costs but is highly dependent upon landowners willing to accept what may be significant changes in land use expectations. Concluding recommendations exhort State and Federal agencies involved with river resource management to work together to provide economic incentives and technical assistance for towns and landowners to make decisions that resolve immediate conflicts with the long term watershed solutions in mind

    Evaluation of Methodology Involved in a Selected Stock Market Timing Technique

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    An empirical study to determine the efficiency of a selected timing technique for stock market traders was conducted. The subject technique was devised by the founder of a well-known investment advisory service and utilized manipulations involving daily price advances and declines on the New York Stock Exchange. The technique was applied to twelve stocks meeting the prescribed selection criteria as well as Standard and Poor's five-hundred stock composite index for varying time periods during the three years ended June 30, 1966. The results of these tests were compared to those evolving through use of a simple buyand- hold policy applied to the same stocks during the same periods. The findings in all tests indicated that the subject technique was inefficient and substantially inferior to a naive buy-and-hold policy. Extremely interesting implications for further study were generated by certain of the test results. These results indicated that superior yields might be obtained by purchase of stocks which, pricewise, have recently outperformed the market as a whole. In addition to suggesting approaches to further research in this area, the pertinent fin.dings were related to past research efforts.Business Administratio

    Detection of unhealthy region of plant leaves and classification of plant leaf diseases using texture features

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    Plant diseases have turned into a dilemma as it can cause significant reduction in both quality and quantity of agricultural products.  Automatic detection of plant diseases is an essential research topic as it may prove benefits in monitoring large fields of crops, and thus automatically detect the symptoms of diseases as soon as they appear on plant leaves.  The proposed system is a software solution for automatic detection and classification of plant leaf diseases.  The developed processing scheme consists of four main steps, first a color transformation structure for the input RGB image is created, then the green pixels are masked and removed using specific threshold value followed by segmentation process, the texture statistics are computed for the useful segments, finally the extracted features are passed through the classifier.  The proposed algorithm’s efficiency can successfully detect and classify the examined diseases with an accuracy of 94%.  Experimental results on a database of about 500 plant leaves confirm the robustness of the proposed approach.   Keywords: HSI, color co-occurrence matrix, texture, SVM, plant leaf disease

    An improved approach for flight readiness certification: Probabilistic models for flaw propagation and turbine blade failure. Volume 1: Methodology and applications

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    An improved methodology for quantitatively evaluating failure risk of spaceflight systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with analytical modeling of failure phenomena to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in analytical modeling, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which analytical models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes. These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. State-of-the-art analytical models currently employed for designs failure prediction, or performance analysis are used in this methodology. The rationale for the statistical approach taken in the PFA methodology is discussed, the PFA methodology is described, and examples of its application to structural failure modes are presented. The engineering models and computer software used in fatigue crack growth and fatigue crack initiation applications are thoroughly documented

    An improved approach for flight readiness certification: Probabilistic models for flaw propagation and turbine blade failure. Volume 2: Software documentation

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    An improved methodology for quantitatively evaluating failure risk of spaceflights systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with analytical modeling of failure phenomena to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in analytical modeling, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which analytical models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes. These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. State-of-the-art analytical models currently employed for design, failure prediction, or performance analysis are used in this methodology. The rationale for the statistical approach taken in the PFA methodology is discussed, the PFA methodology is described, and examples of its application to structural failure modes are presented. The engineering models and computer software used in fatigue crack growth and fatigue crack initiation applications are thoroughly documented

    An improved approach for flight readiness certification: Methodology for failure risk assessment and application examples. Volume 2: Software documentation

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    An improved methodology for quantitatively evaluating failure risk of spaceflight systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with engineering analysis to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in engineering analyses of failure phenomena, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which engineering analysis models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes, These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. Conventional engineering analysis models currently employed for design of failure prediction are used in this methodology. The PFA methodology is described and examples of its application are presented. Conventional approaches to failure risk evaluation for spaceflight systems are discussed, and the rationale for the approach taken in the PFA methodology is presented. The statistical methods, engineering models, and computer software used in fatigue failure mode applications are thoroughly documented

    An improved approach for flight readiness certification: Methodology for failure risk assessment and application examples, volume 1

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    An improved methodology for quantitatively evaluating failure risk of spaceflight systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with engineering analysis to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in engineering analyses of failure phenomena, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which engineering analysis models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes. These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. Conventional engineering analysis models currently employed for design of failure prediction are used in this methodology. The PFA methodology is described and examples of its application are presented. Conventional approaches to failure risk evaluation for spaceflight systems are discussed, and the rationale for the approach taken in the PFA methodology is presented. The statistical methods, engineering models, and computer software used in fatigue failure mode applications are thoroughly documented

    First empirical evaluation of the link between attachment, social cognition and borderline features in adolescents

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    OBJECTIVE: Several developmental models of borderline personality disorder (BPD) emphasize the role of disrupted interpersonal relationships or insecure attachment. As yet, attachment quality and the mechanisms by which insecure attachment relates to borderline features in adolescents have not been investigated. In this study, we used a multiple mediational approach to examine the cross-sectional interplay between attachment, social cognition (in particular hypermentalizing), emotion dysregulation, and borderline features in adolescence, controlling for internalizing and externalizing symptoms. METHODS: The sample included 259 consecutive admissions to an adolescent inpatient unit (Mage=15.42, SD=1.43; 63.1% female). The Child Attachment Interview (CAI) was used to obtain a dimensional index of overall coherence of the attachment narrative. An experimental task was used to assess hypermentalizing, alongside self-report measures of emotion dyregulation and BPD. RESULTS: Our findings suggested that, in a multiple mediation model, hypermentalizing and emotion dysregulation together mediated the relation between attachment coherence and borderline features, but that this effect was driven by hypermentalizing; that is, emotion dysregulation failed to mediate the link between attachment coherence and borderline features while hypermentalizing demonstrated mediational effects. CONCLUSIONS: The study provides the first empirical evidence of well-established theoretical approaches to the development of BPD

    An improved approach for flight readiness certification: Methodology for failure risk assessment and application examples. Volume 3: Structure and listing of programs

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    An improved methodology for quantitatively evaluating failure risk of spaceflight systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with engineering analysis to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in engineering analyses of failure phenomena, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which engineering analysis models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes. These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. Conventional engineering analysis models currently employed for design of failure prediction are used in this methodology. The PFA methodology is described and examples of its application are presented. Conventional approaches to failure risk evaluation for spaceflight systems are discussed, and the rationale for the approach taken in the PFA methodology is presented. The statistical methods, engineering models, and computer software used in fatigue failure mode applications are thoroughly documented
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