3,532 research outputs found

    A parallel and adaptive multigrid solver for the solutions of the optimal control of geometric evolution laws in two and three dimensions

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    We present a problem concerning the optimal control of geometric evolution laws. This is a minimisation problem that aims to find a control η which minimises the objective functional J subject to some imposed constraints. We apply this methodology to an application of whole cell tracking. Given two sets of data of cell morphologies, we may solve the optimal control problem to dynamically reconstruct the cell movements between the time frame of these two sets of data. This problem is solved in two and three space dimensions, using a state-of-the-art numerical method, namely multigrid, with adaptivity and parallelism

    An optimal control approach to cell tracking

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    Cell tracking is of vital importance in many biological studies, hence robust cell tracking algorithms are needed for inference of dynamic features from (static) in vivo and in vitro experimental imaging data of cells migrating. In recent years much attention has been focused on the modelling of cell motility from physical principles and the development of state-of-the art numerical methods for the simulation of the model equations. Despite this, the vast majority of cell tracking algorithms proposed to date focus solely on the imaging data itself and do not attempt to incorporate any physical knowledge on cell migration into the tracking procedure. In this study, we present a mathematical approach for cell tracking, in which we formulate the cell tracking problem as an inverse problem for fitting a mathematical model for cell motility to experimental imaging data. The novelty of this approach is that the physics underlying the model for cell migration is encoded in the tracking algorithm. To illustrate this we focus on an example of Zebrafish (Danio rerio's larvae) Neutrophil migration and contrast an ad-hoc approach to cell tracking based on interpolation with the model fitting approach we propose in this study

    Spherical solid-propellant rocket motor Patent

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    Spherical solid propellant rocket engine desig

    The Use of Gamification and Its Impact on Crowdfunding Participation:

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    This action research study examined how the use of two gamification tools (CreatiCUBE and Children Story Time) can increase the interest of venture capitalists to invest in the start-up company that designed both tools. Data were collected through interviews and field notes using convenience sampling. The eight participants in this study were people who had previous knowledge of and supported the two projects. The initial findings revealed that participants and potential investors were inclining to support Children Story Time rather than CreatiCUBE. The flexible nature of action research allowed a refocus of the study on the latter gamification tool. Four themes emerged from the analysis of data: 1) participants had no particular interest in funding; 2) funding was a byproduct of market demand; 3) Children Story Time was a market-disrupting tool; and 4) strategies emerged to secure venture capital investment. Three analytical theories shed light on the findings: Bourdieu’s cultural capital theory and Csikszentmikalyi’s flow and transactional leadership theories. Findings provide evidence that, to secure financial investment, startup entrepreneurs need to immerse in the cultural capital of their community and appeal to the support of close friends and family members to create a workable application, demonstrate the application has over 10,000 daily users, and hold a successful Kickstarter campaign

    High-throughput in-situ characterization and modelling of precipitation kinetics in compositionally graded alloys

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    The development of new engineering alloy chemistries is a time consuming and iterative process. A necessary step is characterization of the nano/microstructure to provide a link between the processing and properties of each alloy chemistry considered. One approach to accelerate the identification of optimal chemistries is to use samples containing a gradient in composition, ie. combinatorial samples, and to investigate many different chemistries at the same time. However, for engineering alloys, the final properties depend not only on chemistry but also on the path of microstructure development which necessitates characterization of microstructure evolution for each chemistry. In this contribution we demonstrate an approach that allows for the in-situ, nanoscale characterization of the precipitate structures in alloys, as a function of aging time, in combinatorial samples containing a composition gradient. The approach uses small angle x-ray scattering (SAXS) at a synchrotron beamline. The Cu-Co system is used for the proof-of-concept and the combinatorial samples prepared contain a gradient in Co from 0% to 2%. These samples are aged at temperatures between 450{\textdegree}C and 550{\textdegree}C and the precipitate structures (precipitate size, volume fraction and number density) all along the composition gradient are simultaneously monitored as a function of time. This large dataset is used to test the applicability and robustness of a conventional class model for precipitation that considers concurrent nucleation, growth and coarsening and the ability of the model to describe such a large dataset.Comment: Published in Acta Materiali

    Long term time-lapse microgravity and geotechnical monitoring of relict salt-mines, Marston, Cheshire, UK.

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    The area around the town of Northwich in Cheshire, U. K., has a long history of catastrophic ground subsidence caused by a combination of natural dissolution and collapsing abandoned mine workings within the underlying Triassic halite bedrock geology. In the village of Marston, the Trent and Mersey Canal crosses several abandoned salt mine workings and previously subsiding areas, the canal being breached by a catastrophic subsidence event in 1953. This canal section is the focus of a long-term monitoring study by conventional geotechnical topographic and microgravity surveys. Results of 20 years of topographic time-lapse surveys indicate specific areas of local subsidence that could not be predicted by available site and mine abandonment plan and shaft data. Subsidence has subsequently necessitated four phases of temporary canal bank remediation. Ten years of microgravity time-lapse data have recorded major deepening negative anomalies in specific sections that correlate with topographic data. Gravity 2D modeling using available site data found upwardly propagating voids, and associated collapse material produced a good match with observed microgravity data. Intrusive investigations have confirmed a void at the major anomaly. The advantages of undertaking such long-term studies for near-surface geophysicists, geotechnical engineers, and researchers working in other application areas are discussed

    Modernization of the Walker River Irrigation District Water Gauges

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    The Irrigation Training and Research Center (ITRC) and Walker River Irrigation District (WRID) collaborated on WRID’s Water Gauge Improvement Project with support from the Bureau of Reclamation, U.S. Department of Interior in Carson City, Nevada. This paper presents a summary of the proposed plan and implementation for improving water gauges in WRID with strategic engineering recommendations for new hardware and control equipment; water management strategies; flow measurement devices; and integration of a new district-wide SCADA system. Field investigations and engineering analyses were carried out by the ITRC in 2009 to inspect existing WRID infrastructure, to review current operational procedures, and to interview district staff. This information was analyzed and compiled to summarize the scope of work for system improvements. The ITRC prioritized the order of engineering implementation and automation recommendations, provided planning-level cost estimates, and has assisted WRID in organizing implementation over the past five years

    Case Study: Modernization of the Walker River Irrigation District

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    The Irrigation Training and Research Center (ITRC) and Walker River Irrigation District (WRID) collaborated on the modernization of WRID with support from the Bureau of Reclamation, U.S. Department of Interior in Carson City, Nevada. This paper presents an update to the USCID case study that was presented in 2014 on the initial proposed plan for improving water gauges throughout WRID. There has been phased implementation of the initial proposed plan as well as modification and expansion of that plan. The initial scope of work for system improvements was developed by ITRC in 2009 following field investigations and engineering analyses of existing WRID infrastructure and operational procedures. The initial plan identified twenty primary sites for water gauge improvement and provided strategic engineering recommendations for new hardware, control equipment, and flow measurement devices for the sites, as well as water management strategies and integration of a new SCADA system for the entire district. Additionally, the plan prioritized the order of engineering implementation and automation recommendations and provided planning-level cost estimates. Over the following eight years, ITRC has assisted WRID in organizing implementation, including site-specific designs as well as updating hardware and control equipment recommendations to align with current technology. To date, twelve of the original twenty sites have been implemented. Twenty additional sites have been identified, fourteen of which have already been implemented. Additionally, up to six buffer reservoir sites located throughout the district are currently being developed

    Geodynamic setting and origin of the Oman/UAE ophiolite

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    The ~500km-long mid-Cretaceous Semail nappe of the Sultanate of Oman and UAE (henceforth referred to as the Oman ophiolite) is the largest and best-preserved ophiolite complex known. It is of particular importance because it is generally believed to have an internal structure and composition closely comparable to that of crust formed at the present-day East Pacific Rise (EPR), making it our only known on-land analogue for ocean lithosphere formed at a fast spreading rate. On the basis of this assumption Oman has long played a pivotal role in guiding our conceptual understanding of fast-spreading ridge processes, as modern fast-spread ocean crust is largely inaccessible
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