3,175 research outputs found

    An investigation of using an RQP based method to calculate parameter sensitivity derivatives

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    Estimation of the sensitivity of problem functions with respect to problem variables forms the basis for many of our modern day algorithms for engineering optimization. The most common application of problem sensitivities has been in the calculation of objective function and constraint partial derivatives for determining search directions and optimality conditions. A second form of sensitivity analysis, parameter sensitivity, has also become an important topic in recent years. By parameter sensitivity, researchers refer to the estimation of changes in the modeling functions and current design point due to small changes in the fixed parameters of the formulation. Methods for calculating these derivatives have been proposed by several authors (Armacost and Fiacco 1974, Sobieski et al 1981, Schmit and Chang 1984, and Vanderplaats and Yoshida 1985). Two drawbacks to estimating parameter sensitivities by current methods have been: (1) the need for second order information about the Lagrangian at the current point, and (2) the estimates assume no change in the active set of constraints. The first of these two problems is addressed here and a new algorithm is proposed that does not require explicit calculation of second order information

    An investigation of new methods for estimating parameter sensitivities

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    The method proposed for estimating sensitivity derivatives is based on the Recursive Quadratic Programming (RQP) method and in conjunction a differencing formula to produce estimates of the sensitivities. This method is compared to existing methods and is shown to be very competitive in terms of the number of function evaluations required. In terms of accuracy, the method is shown to be equivalent to a modified version of the Kuhn-Tucker method, where the Hessian of the Lagrangian is estimated using the BFS method employed by the RQP algorithm. Initial testing on a test set with known sensitivities demonstrates that the method can accurately calculate the parameter sensitivity

    Typicality and Familiarity Effects in Children\u27s Memory: the Interaction of Processing and the Knowledge Base.

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    Third- and sixth-graders and adults participated in an experiment based upon Hunt and Einstein\u27s (1981) theory which relates study activities or processing task to subsequent memory performance. Participants performed a processing task designed to emphasize either relational or item-specific information. In addition, the information about the words available in each subject\u27s knowledge base was measured in two ways: relational information was assessed with a typicality rating task and item-specific information was assessed with an attribute listing task. The experiment consisted of three phases. In the first phase subjects performed one of two processing tasks on a list containing typical, atypical and unfamiliar exemplers of a semantic category. One group of subjects sorted the words into categories (the relational task) the other group rated the words for pleasantness (the item-specific task). In the second phase, subjects\u27 memory for the words was tested on a free recall test. In the third phase the knowledge base assessment tasks were performed. The knowledge base measures indicated: the relative amount of relational versus item-specific information available for typical, atypical and unfamiliar words is different for each type of word and that amount of relational and item-specific information in the knowledge base changes with age. As predicted by the theory, recall was influenced by the interaction of word type with processing task. Finally, parallels between free recall results and the knowledge base measures indicated that knowledge base development interacts with the processing task to influence what is recalled by subjects at the three age levels

    Where should buffers go? Modeling riparian habitat connectivity in northeast Kansas

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    Through many funding programs, riparian buffers are being created on agricultural lands to address significant water quality problems. Society and landowners are demanding many other environmental and social services (e.g., wildlife habitat and income diversification) from this practice. Resource planners therefore need to design riparian buffer systems in the right places to provide multiple services. However, scientific guidance for this is lacking. We developed a geographic information system (GIS)-based assessment method for quickly identifying where buffers can be established to restore connectivity of riparian areas for the benefit of terrestrial wildlife. An area in northeastern Kansas was selected to evaluate this tool. Species with limited dispersal capabilities were used as indicators for riparian connectivity. To improve connectivity, results indicated that 22 percent of the perennial stream length in the study area would need riparian buffers. This coarse-filter approach appears to be appropriate for large area planning and can be used singly or in combination with other GIS-guided resource assessments to guide riparian buffer design and implementation

    Lunar Constellation of Frozen Elliptical Inclined Orbits

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    A document discusses the design of orbits of spacecraft for relaying communications between Earth stations and robotic and human explorers in craters in one of the polar regions on the Moon

    Measles Rash Identification Using Residual Deep Convolutional Neural Network

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    Measles is extremely contagious and is one of the leading causes of vaccine-preventable illness and death in developing countries, claiming more than 100,000 lives each year. Measles was declared eliminated in the US in 2000 due to decades of successful vaccination for the measles. As a result, an increasing number of US healthcare professionals and the public have never seen the disease. Unfortunately, the Measles resurged in the US in 2019 with 1,282 confirmed cases. To assist in diagnosing measles, we collected more than 1300 images of a variety of skin conditions, with which we employed residual deep convolutional neural network to distinguish measles rash from other skin conditions, in an aim to create a phone application in the future. On our image dataset, our model reaches a classification accuracy of 95.2%, sensitivity of 81.7%, and specificity of 97.1%, indicating the model is effective in facilitating an accurate detection of measles to help contain measles outbreaks

    Measurement of vortex flow fields

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    A 3-D laser fluorescence anemometer (LFA) was designed, built, and demonstrated for use in the Langley 16 x 24 inch Water Tunnel. Innovative optical design flexibility combined with compact and portable data acquisition and control systems were incorporated into the instrument. This will allow its use by NASA in other test facilities. A versatile fiber optic system facilities normal and off-axis laser beam alignment, removes mirror losses and improves laser safety. This added optical flexibility will also enable simple adaptation for use in the adjacent jet facility. New proprietary concepts in transmitting color separation, light collection, and novel prism separation of the scattered light was also designed and built into the system. Off-axis beam traverse and alignment complexity led to the requirement for a specialized, programmable transverse controller, and the inclusion of an additional traverse for the off-axis arm. To meet this challenge, an 'in-house' prototype unit was designed and built and traverse control software developed specifically for the water tunnel traverse applications. A specialized data acquisition interface was also required. This was designed and built for the LFA system

    Mid- and Late-Life Divorce and Parents' Perceptions of Emerging Adult Children's Emotional Reactions

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    A paucity of research exists pertaining to the experiences of emerging adult children in the context of parental divorce. This study uses Paul R. Amato's divorce-stress-adjustment framework to organize a set of predictors that potentially influence parents' perceptions of their emerging adult children's emotional reactions to a divorce. Data come from a nationally representative AARP study, from which we analyzed a sample of 283 parents who experienced a divorce at age 40 years or older. Results indicate that parental gender, nature of contact with the ex-partner, divorce timing, time spent contemplating divorce, a history of parental divorce, and the reason for divorce influence parents' perceptions of their emerging adult children's reaction to the divorce. Implications, limitations, and future direction for research are discussed
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