Browsing by Subject "Instrumentation"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    An arc across fields of study: electricity in Physics and Chemistry (1751-1807)
    (2010-10) Fisher, Amy Alice
    Electricity does not obey disciplinary boundaries, yet its history is dominated by stories of heroic physicists and engineers. These histories do not reflect its dynamic nature. My dissertation analyzes how the concept ‘electricity’ evolved from a material fluid to a force as scientists’ chemical concepts changed. By analyzing the history of electricity from a chemical perspective, my dissertation demonstrates that the study of electrical phenomena played an important role in the emerging field of chemistry. It focuses on the period between 1751, when Benjamin Franklin published Experiments and Observations on Electricity, and 1807, when Humphry Davy published On Some Chemical Agencies of Electricity.
  • Thumbnail Image
    Item
    Instrumentation and Fabrication of Two High-Strength Concrete Prestressed Bridge Girders
    (Minnesota Department of Transportation, 1998-01) Kielb, Jeffrey; French, Catherine E.; Leon, Roberto T.; Shield, Carol K.
    This report describes the design, instrumentation, construction, and test set-up of two high-strength concrete prestressed bridge girders. The girder specimens were constructed to evaluate prestress transfer length, prestress losses, flexural fatigue, ultimate flexural strength, and ultimate shear strength. Each test girder was a 132.75-foot long, 46-inch deep, Minnesota Department of Transportation (Mn/DOT) 45M girder section reinforced with 46 0.6-inch diameter 270 ksi prestressing strands. The 28-day nominal compressive strength of the girders was 10,500 psi. Each girder was made composite with a 9-inch thick, 48-inch wide composite concrete deck cast on top with a nominal compressive strength of 4000 psi. Girder I used a concrete mix incorporating crushed limestone aggregate while Girder II utilized round glacial gravel aggregate in the mix with the addition of microsilica. In addition, the two test girders incorporated two different end patterns of prestressing--draping versus a combination of draping and debonding--and two different stirrup configurations--standard Mn/DOT U versus a modified U with leg extensions. More than 200 strain gages were imbedded in each girder during construction. Other reports present flexural and shear testing results.
  • Thumbnail Image
    Item
    Instrumentation of Navistar Truck for Data Collection
    (Minnesota Department of Transportation, 2013-01) Alexander, Lee; Phanomchoeng, Gridsada; Rajamani, Rajesh
    The overarching goal of this project was to instrument the new MnDOT Navistar truck used at MN Road. A rugged data acquisition, data recording and wireless transmission system was established for collection of various sensor signals from the truck. The truck was instrumented with a suite of 20 accelerometers, with these accelerometers being located both on the five axles of the truck and on the tractor and trailer bodies. In addition, the truck was instrumented with a differential GPS system and an inertial measurement unit in the tractor cab. A cRIO-based data acquisition system, a rugged laptop and Labview software together serve as a flexible platform for data acquisition. A wireless communication system has been established to communicate trigger signals to roadside cabinets when the truck is at desired GPS locations on the road. Data recording by in-pavement sensors is triggered by this system. Software has also been set up for automatic downloading of data from the truck to a server on the network at MN Road. The experimental performance of the developed system has been verified by multiple tests conducted by the research team. The above instrumentation of the truck will enable data collection on truck vibrations, enable analysis of correlations between truck vibrations and variations in signals of weigh-inmotion sensors, and enable recording of truck movements and pavement loads at MnROAD.
  • Thumbnail Image
    Item
    Load Rating Assessment of Three Slab-Span Bridges Over Shingle Creek
    (Minnesota Department of Transportation, 2022-08) Hill, Kendall A.; Dymond, Benjamin Z.; Hedegaard, Brock D.; Linderman, Lauren E.
    Three slab-span bridges crossing Shingle Creek in Brooklyn Center, Minnesota, have poor American Association of State Highway and Transportation Officials (AASHTO) load rating factors for certain truck configurations. Characterization of load distribution is useful for determining the load rating of bridges, but results in the literature have shown that the AASHTO code results in conservative load rating factors. The focus of this study was to determine if the load rating of the three concrete slab-span bridges was conservative and could be improved using results from live load testing and finite element analysis. Field testing used a suite of instrumentation that included displacement transducers, strain gauges, accelerometers, and tiltmeters. A three-dimensional solid-element finite element model was used to determine an expected range of behaviors and corroborate the field data regarding how load distributed when placed near and away from a barrier. In addition, a method for developing a simple plate model of slab span bridges was developed considering in-situ material properties and effects of secondary elements such as barriers. Results indicated that the AASHTO load rating was conservative, and an improved rating factor could be obtained considering the field test data and computational modeling results.
  • Thumbnail Image
    Item
    Lubricity of biomedical conduits
    (2013-12) Turner, Thomas James
    The research is motivated by the need to explore the inputs and mechanisms responsible for the creation of beneficial tribological coatings on medical grade silicone rubber tubing and how to quantify them. Despite the fact that biomedical conduits are routinely made lubricious by a host of different methods, there is an insufficiency in the present state of knowledge with regard to how to precisely quantify conduit bore lubricity. Test methods, newly invented, to characterize tubing bore lubricity are described in detail with greater emphasis on the extraction of coefficients of friction relative to historical testing methods. A new invention for characterizing the lubricity of biomedical conduits makes use of a pressure cuff or air-bladder to compress a plasma-treated silicone tubing sample onto a friction element. The instrument setup is a metal sliding-friction-element/silicone- tubing system. The tubing is stationary while the friction element that has been inserted into the tubing bore is pulled. The tubing is held in place with a known and regulated pressure, which allows the normal force pressing on the sliding component to be known. The pull force (tangential force) is registered and recorded using a commercial pull-test frame. Knowing the normal and tangential forces means that the coefficient of friction for the system can be extracted using this instrument.The running-in behavior observed during biomedical conduit friction assessment is quantified and a hypothesis regarding its source is set forth. The theme of the hypothesis is that material related to the constituents of silicone rubber is taken up by the friction element (coil, in this case) over several test cycles and thereby alters the system until it stabilizes. Subsequently, the coil becomes equilibrated with the chemical makeup of its environment, and this is why the resistance force stabilizes. The results of extensive experimentation showed that pristine coils displayed markedly more running-in phenomenon when compared to either an exercised coil or a stored-in-silicone tubing coil.The outcome of the thesis is a thorough understanding of tubing bore lubricity quantification.
  • Thumbnail Image
    Item
    Monitoring and Assessment Program for Wabasha County Bridge
    (1998-09) Fick, Damon R.; Schultz, Arturo E.; Bergson, Paul M.; Galambos, Theodore V.
    A 143-m (470-foot) span steel truss bridge, the Wabasha County Bridge crosses the Mississippi River at Wabasha, Minn. In November 1996, the Minnesota Department of Transportation (Mn/DOT) implemented a retrofit strategy to mitigate perceptible vibrations in several truss members at moderate and strong wind gusts. In this strategy, Mn/DOT installed a "central cord" of tubular members, halfway between top and bottom cords, to reduce the effective length of the truss members, thereby increasing the natural frequencies of vibration and reducing the amplitude of vibration and the associated strains. This report documents the monitoring and assessment program used to investigate the dynamic response and efficacy of the retrofit strategy for the Wabasha Country Bridge. Researchers determined amplitudes and frequencies of the vibration for the longest diagonal member. The measured frequencies are larger than those estimated before the retrofit and have resulted in reduced strains and displacements from vibration. Maximum strain levels at the quarter point of the member are estimated to be small after the retrofit, with peak values corresponding to 8.6 MPa (1.2 ksi).
  • Thumbnail Image
    Item
    New Instrumentation and Methods for Studying Heterogeneous Vapor Uptake by Aerosol Particles Ranging In Size From One Molecule to 10nm
    (2013-10) Oberreit, Derek
    Aerosol particles in the presence of a vapor will often change in size and composition due to heterogeneous vapor uptake. The physics and thermodynamics of this phenomenon are not well understood for particles less than ~10 nm where traditional models using bulk properties begin to break down. Further, existing methods for measuring/quantifying vapor uptake by particles are not effective for examining particles below 5 nm in size, and at relatively high vapor saturation ratios. This dissertation presents two new methods for measuring vapor uptake by aerosol particles in this size range. Each system measures the change in electrical mobility (which can be related to size) of aerosol particles when they are introduced to a vapor of known concentration. The first system consists of a tandem High Resolution Differential Mobility Analyzer - Drift Tube Ion Mobility Analyzer (HRDMA-DTIMS) for measuring uptake by particles ranging from ~2nm to >12nm, and the second system is a tandem HRDMA-Mass Spectrometer for measuring uptake by particles ranging from a single molecule to ~2nm. For the HRDMA-DTIMS system a new drift tube ion mobility spectrometer was developed and is described, with the goal of high resolution and fast measurement times. The device is capable of sub second mobility distribution scans and resolving powers similar to DMAs currently used in similar vapor uptake experiments. Measurement of water vapor uptake by hygroscopic salts of lithium iodide and sodium iodide particles compared to theoretical calculations exposes the flaws in existing vapor uptake models. The precision of the growth factor (wet diameter / dry diameter) measured using this system is shown to be ~0.2% for the presented data. For the HRDMA-MS system we are able to identify electrospray generated ions of a specific composition and then measure their change in electrical mobility as a function of relative humidity. Using this system we measured vapor uptake by alkyl halide salt cluster ions ranging from one to 27 molecules. We also describe how structures determined using density functional theory can be used to estimate the change in electrical mobility due to additions of vapor molecules. In addition to describing new instrumentation and systems, a model for estimating mobility changes based on collision mechanics as well as thermodynamics of individual molecule uptake is presented. This model can be applied to any vapor uptake measurement systems.