1,863 research outputs found

    Spatially Sampled Robust Repetitive Control

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    Development of Integration Software for Multiple Inkjet Functionalization Systems

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    Inkjet printing is widely used in functional product manufacturing. Performing a printing task requires communication and synchronization among multiple subsystems (e.g. motion and drop ejection), which introduces complexity in the overall printing system. A user interface has been developed, which enables users to input printing parameters and patterns for printing functional materials. The interface then sends commands to the controllers that execute the printing process. The software can also be expanded to carry out standard experiments for functional printing research and characterization. Moreover, the software is transferable to multiple systems. One application explored using the software is drug anti- counterfeiting research by printing edible coloring onto pills

    Processing liquid metal for conformable electronics

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    Future generations of robots, electronics, and assistive medical devices will include systems that are soft, elastically deformable, and may adapt their functionality in unstructured environments. This will require soft active materials for power circuits and sensing of deformation and contact pressure. Liquid-embedded elastomer electronics offer one solution as key elements of highly deformable and soft robotic systems. Several designs for stretchable conductors and soft sensory skins (including strain, pressure, and curvature sensors) based on a liquid-embedded-elastomer approach have been developed. Many of these fluid–elastomer composites utilize liquid metal alloys due to their high conductivities and inherent compliance. Understanding how these alloys can be processed for high-yield manufacturability is critical to the development of parallel processing technology, which is needed to create more complex and low-cost systems. This discussion will highlight surface interactions between droplets of gallium–indium alloys and elastomeric substrates, and the implementation of this study to selective patterning, direct-writing, and inkjet printing of hyperelastic electronic components

    MODELING AND EXPERIMENTAL VERIFICATION OF TORQUE RIPPLE IN PERMANENT MAGNET DC MOTORS

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    ABSTRACT In this paper we have developed a simple parametric model based on motor geometries to estimate the torque ripple in permanent-magnet DC (PMDC) motors. Torque ripple is the combined results of many different motor design parameters such as magnetic material properties and geometry as well as rotor slot geometry. As the PMDC motors are being used in more precision applications while being produced at a lower price, the effect of torque ripple is becoming an important issued for precision motion control. The main objective of this study is to identify motor parameters that affect the magnitude of the torque ripples as well as developing a cost effective measuring device for motor vendors. The analytical model focused on the effect of air gap volume on effective magnetic flux and in terms impact the torque generation. The effectiveness of the proposed model was verified by experimental data collected with motors from four large volume motor vendors that meets the same design specification. Sensitivity analysis was also performed to identify the key motor parameters that impacted the magnitude of the torque ripple. INTRODUCTION The use of brushed permanent magnet DC (PMDC) motors in machines that are used in precision application has become more common over the years. The reason for this trend is due to an increase in quality and cost effectiveness through advances in manufacturing processes. These advances have not however eliminated a periodic fluctuation of the output torque of the motor which is dependent on angular position and can be termed torque ripple (TR). This paper will first discuss a model of the motor developed torque T D and TR and then compar

    Development and Evaluation of Low-Cost CO2 Sensors for Buildings

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    There is a significant opportunity to improve building energy efficiency and indoor environmental quality by accurately monitoring CO2 levels. However, current CO2 sensors tend to be expensive or require regular recalibration. This work presents research related to the initial development and evaluation of two novel CO2 sensors based on chemiresistive and resonant mass sensing techniques. Prototype sensors were assessed in a bench-top test chamber at temperatures, humidity levels, and CO2 concentrations, typical of indoor environments. Under these conditions, prototype sensors required only 60 mW of power, or less. Further, each sensor was developed to have a footprint of less than 25 mm2 and a cost of less than $50. Given the relative low cost, small size, and potential for low power consumption, these sensors may serve as an attractive alternative to the commercial CO2 sensors that are currently available

    Mass Calibration and Cosmological Analysis of the SPT-SZ Galaxy Cluster Sample Using Velocity Dispersion σv\sigma_v and X-ray YXY_\textrm{X} Measurements

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    We present a velocity dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg2 of the survey along with 63 velocity dispersion (σv\sigma_v) and 16 X-ray Yx measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. The calibrations using σv\sigma_v and Yx are consistent at the 0.6σ0.6\sigma level, with the σv\sigma_v calibration preferring ~16% higher masses. We use the full cluster dataset to measure σ8(Ωm/0.27)0.3=0.809±0.036\sigma_8(\Omega_ m/0.27)^{0.3}=0.809\pm0.036. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming the sum of the neutrino masses is ∑mν=0.06\sum m_\nu=0.06 eV, we find the datasets to be consistent at the 1.0σ\sigma level for WMAP9 and 1.5σ\sigma for Planck+WP. Allowing for larger ∑mν\sum m_\nu further reconciles the results. When we combine the cluster and Planck+WP datasets with BAO and SNIa, the preferred cluster masses are 1.9σ1.9\sigma higher than the Yx calibration and 0.8σ0.8\sigma higher than the σv\sigma_v calibration. Given the scale of these shifts (~44% and ~23% in mass, respectively), we execute a goodness of fit test; it reveals no tension, indicating that the best-fit model provides an adequate description of the data. Using the multi-probe dataset, we measure Ωm=0.299±0.009\Omega_ m=0.299\pm0.009 and σ8=0.829±0.011\sigma_8=0.829\pm0.011. Within a ν\nuCDM model we find ∑mν=0.148±0.081\sum m_\nu = 0.148\pm0.081 eV. We present a consistency test of the cosmic growth rate. Allowing both the growth index γ\gamma and the dark energy equation of state parameter ww to vary, we find γ=0.73±0.28\gamma=0.73\pm0.28 and w=−1.007±0.065w=-1.007\pm0.065, demonstrating that the expansion and the growth histories are consistent with a LCDM model (γ=0.55; w=−1\gamma=0.55; \,w=-1).Comment: Accepted by ApJ (v2 is accepted version); 17 pages, 6 figure

    Analysis of Sunyaev-Zel'dovich Effect Mass-Observable Relations using South Pole Telescope Observations of an X-ray Selected Sample of Low Mass Galaxy Clusters and Groups

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    (Abridged) We use 95, 150, and 220GHz observations from the SPT to examine the SZE signatures of a sample of 46 X-ray selected groups and clusters drawn from ~6 deg^2 of the XMM-BCS. These systems extend to redshift z=1.02, have characteristic masses ~3x lower than clusters detected directly in the SPT data and probe the SZE signal to the lowest X-ray luminosities (>10^42 erg s^-1) yet. We develop an analysis tool that combines the SZE information for the full ensemble of X-ray-selected clusters. Using X-ray luminosity as a mass proxy, we extract selection-bias corrected constraints on the SZE significance- and Y_500-mass relations. The SZE significance- mass relation is in good agreement with an extrapolation of the relation obtained from high mass clusters. However, the fit to the Y_500-mass relation at low masses, while in good agreement with the extrapolation from high mass SPT clusters, is in tension at 2.8 sigma with the constraints from the Planck sample. We examine the tension with the Planck relation, discussing sample differences and biases that could contribute. We also present an analysis of the radio galaxy point source population in this ensemble of X-ray selected systems. We find 18 of our systems have 843 MHz SUMSS sources within 2 arcmin of the X-ray centre, and three of these are also detected at significance >4 by SPT. Of these three, two are associated with the group brightest cluster galaxies, and the third is likely an unassociated quasar candidate. We examine the impact of these point sources on our SZE scaling relation analyses and find no evidence of biases. We also examine the impact of dusty galaxies using constraints from the 220 GHz data. The stacked sample provides 2.8σ\sigma significant evidence of dusty galaxy flux, which would correspond to an average underestimate of the SPT Y_500 signal that is (17+-9) per cent in this sample of low mass systems.Comment: 15 pages, 7 figure
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