56,066 research outputs found

    Breaking Down Link Rot: The Chesapeake Project Legal Information Archive’s Examination of URL Stability

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    Ms. Rhodes explores URL stability, measured by the prevalence of link rot over a three-year period, among the original URLs for law- and policy-related materials published to the web and archived though the Chesapeake Project, a collaborative digital preservation initiative under way in the law library community. The results demonstrate a significant increase in link rot over time in materials originally published to seemingly stable organization, government, and state web sites

    Introducing Tapestries

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    Professor Jane Rhodes introduces Tapestries

    Determining Efficacy of a Passive Exoskeleton for Running

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    A Valparaiso University engineering senior design team is developing a lower-body exoskeleton prototype to increase the user’s running efficiency by 2%. The device is passive, which means that all elements of the system are powered by the user’s motion and impact with the ground. This is done via elastic fabric elements and spring steel actuators that are attached at the user’s hip, knee and ankle. The device’s effectiveness was tested using a VO2-max test in which the single test subject ran on a treadmill at a constant pace with and without the device. The test recorded the amount of oxygen consumed by the user during the trials, which is directly correlated to the calories burned by the user during the trials. As the experiment has a single test subject due to the user-specific dimensions of the prototype, many trials of the VO2 max test were performed in Spring 2020 to yield a larger sample size for analysis. The team used the output data to determine if there is statistically significant evidence that the user running with the device is more efficient than the user running without the device. Analysis was performed using Python and the proprietary software used to record data from VO2-max tests. A repeatable analysis pipeline was created to enable the research team to rapidly determine if changes to the design are beneficial. This pipeline was used to continue the development of the prototype throughout the Spring 2020 semester

    Homogenization of locally stationary diffusions with possibly degenerate diffusion matrix

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    This paper deals with homogenization of second order divergence form parabolic operators with locally stationary coefficients. Roughly speaking, locally stationary coefficients have two evolution scales: both an almost constant microscopic one and a smoothly varying macroscopic one. The homogenization procedure aims to give a macroscopic approximation that takes into account the microscopic heterogeneities. This paper follows "Diffusion in a locally stationary random environment" (published in Probability Theory and Related Fields) and improves this latter work by considering possibly degenerate diffusion matrices. The geometry of the homogenized equation shows that the particle is trapped in subspace of R^d.Comment: To appear in Annales de l'institut henri poincare (link of the journal: http://www.imstat.org/aihp/

    Scanning afocal laser velocimeter projection lens system

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    A method and apparatus for projecting and focusing parallel laser light beams from a laser doppler velocimeter on a target area are described. The system includes three lenses. Two lenses work together as a fixed afocal lens combination. The third lens is a movable scanning lens. Parallel laser beams travel from the velocimeter through the scanning lens and through the afocal lens combination and converge, i.e., are focused, somewhere beyond. Moving the scanning lens relative to the fixed afocal combination results in a scanning of the focus area along the afocal combination's optical axis

    Clevis joint for deployable space structures

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    This invention relates generally to pin clevis joints, and more particularly, to zero play pin clevis joints for connecting structural members of a deployable space structure. A joint includes a pin, a tang, and a shackle. The pin is tapered at the same angle as the bores extending through the projections of the shackle and the tang. A spring washer biases the tang onto the tapered sidewall of the pin. The invention solves the free play problem associated with deployable space structures by using a tapered pin which is held in tapered holes by the spring washers

    Preloaded space structural coupling joints

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    A coupling device for tubular members of large truss structures with a locking collar being the only moving part is described. Each tubular member is constructed with an end bell section that has a belled flange with a mating face, and a necked area which is smaller in diameter than the tubular members to be joined. A split ring is affixed to each tubular member and is constructed so that when two tubular members are laterally moved into axial alignment and the collar is rotated over it, the split ring loads the joint with axial forces by pressing the belled flange mating surfaces together, and a preloading force is provided by the collar mating with a taper on the outside of the split rings. All free play is thereby removed by preloaded force. A major object is to provide an ability to remove and replace individual tubular members without disturbing other structural parts of a truss structure. An additional anticipated use of this joint is to couple high pressure fluid lines
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