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Waves and electromagnetic radiation
Published in Andrew Norton, Dynamic Fields and Waves, 2019
Although light is generally unpolarized, it is possible to polarize it by various means; and polarized light has several applications. Probably the best-known method of polarizing light is to pass it through a polarizing filter (known commercially as ‘Polaroid’). When light, initially with many electric field orientations, passes through a polarizing filter, it emerges with only one allowed electric field orientation, as shown in Figure 2.38. The polarizing direction of the filter is established during manufacture by the orientation of the molecules of the polarizing material (which are at right-angles to the allowed electric field orientation). If the polarized light then meets a second polarizing filter, with its polarizing direction at right-angles to that of the first filter, no light at all can pass. Two such Polaroid sheets are said to be crossed.
P
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
polarization-sensitive device electric susceptibility and the applied electric field intensity. polarization-sensitive device device that exhibits behavior dependent on the polarization of the incident electromagnetic wave. A polarizing filter exhibits transmission as a function of the polarization of the light incident on it. polarized capacitor an electrolytic capacitor in which the dielectric film is formed on only one metal electrode. The impedance to the flow of current is then greater in one direction than in the other. Reversed polarity can damage the part if excessive current flow occurs. pole (1) the values of a complex function which cause the value of the function to equal infinity (positive or negative). The poles are all natural frequencies of vibration, or resonances of the circuit described by the equation, but occur at infinite (finite if loss is present) attenuation. They are properties of the function itself, and are not influenced by any other elements in the system (immune to load pulling). (2) one end of a magnet or electromagnet in electrical machines, created by the flux of the machine. (3) the root s of the denominator D(s) = 0, for irreducible rational function X (s) = N (s)D(s) at which points X (s) become unbounded. Rational functions important to signal processing applications include Laplace transforms; the pole locations of Laplace transforms provide valuable information on system stability and other behaviors. pole line any power line which is carried overhead on utility poles. pole of 2-D transfer matrix numbers ( p1 , p2 ) T (z 1 , z 2 ) = a pair of complex that are the root of the 2-D polynomial d(z 1 , z 2 ), i.e., d( p1 , p2 ) = 0, where R p×m [z 1 , z 2 ] is the set of p × m polynomial matrices in z 1 and z 2 with real coefficients. pole pitch the angular distance (normally in electrical degrees) between the axes of two poles in an electrical machine. pole top pin a steel pin onto which a pin insulator is screwed. pole-coefficient sensitivity when a coefficient dk of the polynomial D(s) = d0 + d1 s + d2 s 2 + . . . is a variable parameter then the roots of the polynomial are functions of this parameter. If these roots are simple, one can use the pole-coefficient sensitivity Sd ( pi ) = d pi /d
Detecting a spreading non-indigenous species using multiple methodologies
Published in Lake and Reservoir Management, 2020
Mattias L. Johansson, Sharon Y. Lavigne, Charles W. Ramcharan, Daniel D. Heath, Hugh J. MacIsaac
To assess the detection of veligers using FlowCam, the same samples that were used in CPLM were shaken vigorously by hand, and a 3 mL subsample (0.06–0.18 m3 water sampled) was removed using a disposable plastic pipette. We mixed each subsample with 3 mL of polyvinylpyrrolidone (PVP) solution to increase viscosity and to slow the movement of particles through the flow cell. A 4× objective was used on the FlowCam. We set the flow of plankton through the flow cell to the lowest setting to ensure that the maximum number of particles was captured. A cross-polarizing filter (XPL) was attached to the FlowCam to increase visibility of veligers. We imaged particles using the Image Management System (IMS) under autoimaging mode. We analyzed and manually enumerated captured images of plankton using Visual Spreadsheet software, since many of the images captured by FlowCam IMS software were not veligers (most images captured debris or other plankton), and many veligers were captured only as partial images. Because no native bivalves produce veliger larvae, we could easily confirm dreissenids from manual, visual inspection of saved images (Fluid Imaging Technologies Inc 2011). To assess the possibility that 3 mL subsamples created volume-based artifacts in our veliger counts, we also tested our FlowCam results using subsample volumes of 1 mL (representing 0.02–0.06 m3 lake water sampled), 5 mL (0.1–0.3 m3), 10 mL (0.2–0.6 m3), 15 mL (0.3–0.9 m3), and 25 mL (0.5–1.5 m3) from one high-abundance (southern site) sample and one low-abundance (northern site) sample.
Surface parameters measurement of braided preform based on local edge extreme
Published in The Journal of The Textile Institute, 2019
Zhitao Xiao, Lei Pei, Fang Zhang, Ying Sun, Lei Geng, Jun Wu, Jun Tong, Jia Wen
The image acquisition system mainly consists of a CCD camera with a circular polarizing filter (CPF) and a dome light source (DLS). As illustrated in Figure 5, the braid sample is placed on the horizontal measurement platform followed by the micrometer on one side of the braid, and the surfaces of the micrometer and braid should be kept on the same horizontal plane. The CCD camera with camera lens and CPF attached is then vertically installed over the braid. The DLS is put in front of the braid, and the optical center of the camera is made to go through the center axis of light hole of DLS and the center of braid surface. Finally, the CPF is rotated and the camera exposure value is adjusted to acquire a good image. The CCD camera is an industrial black-and-white CCD camera, so the acquired images are gray-level images.
The Effect of Offset on Burner Fire Whirls
Published in Combustion Science and Technology, 2023
The SPIV system used to analyze the data was identical to that used in Hartl and Smits (2016), with the exception that more recent software was used to analyze the data (DaVis 8.3.0.775). The laser sheet, approximately (1–2 mm) thick, was generated using a 2.5 W pulsed 532 nm Nd:YAG laser (Litron Nano-L 50–50PIV) with 50 mJ per pulse, 532 nm mirrors, a beam focuser and a − 10 mm focal length light sheet generator. Hollow glass microspheres 11.7 m in average diameter were used, with an estimated response time of 170 s inside the whirl core and 420 s outside the whirl core. The particles were introduced into the enclosure through a 12.5 mm tube at one corner, directed parallel to the gap between the staggered cylinder halves. Two Imager sCMOS cameras framing at 25 Hz were used to image the particles. The cameras were placed approximately apart about the center of the data window. To reduce the effects of the flame luminosity, a circular polarizing filter and a 532 nm narrow-band pass filter were placed in front of each camera. The image data were analyzed using successive windows with 50% overlap of , , px, with two final passes at px, yielding vectors. Further details of the experiment and the data acquisition procedures can be found in Hartl and Smits (2016), Hartl (2016), Hartl and Smits (2019).