133 research outputs found

    Cosmological Constraints from the double source plane lens SDSSJ0946+1006

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    We present constraints on the equation of state of dark energy, ww, and the total matter density, ΩM\Omega_{\mathrm{M}}, derived from the double-source-plane strong lens SDSSJ0946+1006, the first cosmological measurement with a galaxy-scale double-source-plane lens. By modelling the primary lens with an elliptical power-law mass distribution, and including perturbative lensing by the first source, we are able to constrain the cosmological scaling factor in this system to be β1=1.404±0.016\beta^{-1}=1.404 \pm 0.016, which implies ΩM=0.330.26+0.33\Omega_{\mathrm{M}}= 0.33_{-0.26}^{+0.33} for a flat Λ\Lambda cold dark matter (Λ\LambdaCDM) cosmology. Combining with a cosmic microwave background prior from Planck, we find ww = 1.170.21+0.20-1.17^{+0.20}_{-0.21} assuming a flat wwCDM cosmology. This inference shifts the posterior by 1σ{\sigma} and improves the precision by 30 per cent with respect to Planck alone, and demonstrates the utility of combining simple, galaxy-scale multiple-source-plane lenses with other cosmological probes to improve precision and test for residual systematic biases.Comment: 9 Pages, 7 Figures. Updated version as published in MNRA

    Improving the Fun Factor at Valpo: A Student Retention Strategy

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    Retention is identified by the university as problem that needs be addressed a part of the overall strategy to improve enrollment at Valpo. This team brainstormed about possible retention issues and discovered that often students describe the campus as “boring” or “uneventful.” Valpo students were polled via the Internet and additional questionnaire handouts on campus. Many students felt as though they lacked information about events on campus and that their RA did not interact with them enough. This data established the extensiveness and the depth of the “lack of fun” problem. Research further revealed that a lot of the events/activities that the students wanted to see at Valpo were already here. So there is definitely a communication breakdown. Students expressed the need for more outreach and encouragement, especially from their immediate authority figure, their RAs, to inform them of what’s going on at Valpo. There was an expressed need for a newsletter that updated students on campus activities via email. (The Torch is too inflexible). Changes need to be made to inform students about campus events. Students proposed a student email newsletter similar to the one sent out to staff (the Campus Chronicle). Students also expressed concern about how the events and activities are promoted to the students, which generally excludes others – the “silo” effect. Since most students must live on campus until they’re upperclassmen, this further increased the issue students have with lack of “fun” on campus. The campaign team will be presenting these research findings to different groups such as IMC and Residential Life

    Automated Lensing Learner: Automated Strong Lensing Identification with a Computer Vision Technique

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    Forthcoming surveys such as the Large Synoptic Survey Telescope (LSST) and Euclid necessitate automatic and efficient identification methods of strong lensing systems. We present a strong lensing identification approach that utilizes a feature extraction method from computer vision, the Histogram of Oriented Gradients (HOG), to capture edge patterns of arcs. We train a supervised classifier model on the HOG of mock strong galaxy-galaxy lens images similar to observations from the Hubble Space Telescope (HST) and LSST. We assess model performance with the area under the curve (AUC) of a Receiver Operating Characteristic (ROC) curve. Models trained on 10,000 lens and non-lens containing images images exhibit an AUC of 0.975 for an HST-like sample, 0.625 for one exposure of LSST, and 0.809 for 10-year mock LSST observations. Performance appears to continually improve with the training set size. Models trained on fewer images perform better in absence of the lens galaxy light. However, with larger training data sets, information from the lens galaxy actually improves model performance, indicating that HOG captures much of the morphological complexity of the arc finding problem. We test our classifier on data from the Sloan Lens ACS Survey and find that small scale image features reduces the efficiency of our trained model. However, these preliminary tests indicate that some parameterizations of HOG can compensate for differences between observed mock data. One example best-case parameterization results in an AUC of 0.6 in the F814 filter image with other parameterization results equivalent to random performance.Comment: 18 pages, 14 figures, summarizing results in figure

    Experimental Investigation of Film Cooling in a Supersonic Environment

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    This thesis reports the results of an experimental investigation of film cooling in a supersonic environment using a modified version of an apparatus originally developed by Daanish Maqbool. A test matrix of conditions relevant to those found in the nozzle extension of the NASA J-2X rocket engine was used as the basis for the testing plan. A film heater was designed and constructed to enable operation at all points in the test matrix. Temperature-time histories from thermocouples embedded in the test section walls were used to compute the spatial evolution of the film cooling effectiveness at each test condition. The results were compared to numerical simulations by NASA's Loci-CHEM CFD tool. Standard speed (30 Hz) Schlieren videos of the film injection region were recorded and new machine vision-based techniques for automatically extracting flow information from Schlieren images were implemented

    Brief Communication

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    The comparison -essentially vector subtraction -gives the direction to the goal. This whole process, which we call vector navigation, was found to be calibrated at recognised sites, such as the nest and a familiar feeder, throughout the life of a forager. If a forager was trained around a one-way circuit in which the result of PI on the return route did not match the result on the outward route, calibration caused the ant's trajectories to be misdirected. We propose a model of vector navigation to suggest how calibration could produce such trajectories

    Still no convincing evidence for cognitive map use by honeybees

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    Cheeseman et al. (1) claim that an ability of honey bees to travel home through a landscape with conflicting information from a celestial compass proves the bees' use of a cognitive map. Their claim involves a curious assumption about the visual information that can be extracted from the terrain: that there is sufficient information for a bee to identify where it is, but insufficient to guide its path without resorting to a cognitive map. We contend that the authors’ claims are unfounded

    OPEN : an open-source platform for developing smart local energy system applications

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    This paper presents OPEN, an open-source software platform for integrated modelling, control and simulation of smart local energy systems. Electric power systems are undergoing a fundamental transition towards a significant proportion of generation and flexibility being provided by distributed energy resources. The concept of ‘smart local energy systems’ brings together related strategies for localised management of distributed energy resources, including active distribution networks, microgrids, energy communities, multi-energy hubs, peer-to-peer trading platforms and virtual power plants. OPEN provides an extensible platform for developing and testing new smart local energy system management applications, helping to bridge the gap between academic research and industry translation. OPEN combines features for managing smart local energy systems which are not provided together by existing energy management tools, including multi-phase distribution network power flow, energy market modelling, nonlinear energy storage modelling and receding horizon optimisation. The platform is implemented in Python with an object-oriented structure, providing modularity and allowing it to be easily integrated with third-party packages. Case studies are presented, demonstrating how OPEN can be used for a range of smart local energy system applications due to its support of multiple model fidelities for simulation and control
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