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Circuits and Circuit Laws
Published in Richard Cadena, Electricity for the Entertainment Electrician & Technician, 2021
Every time you make an electrical connection you are completing a circuit, and every circuit forms a loop from the supply, through the load or loads, and back to the supply. (A load is anything you plug in or anything that uses electricity, like a light, video projector, or chain motor.) Every electrical circuit exhibits the following behaviors: Electricity Always Tries to Return to Its Source. When current flows, it seeks a path back to its supply. The supply provides the energy, which flows through the circuit, and then back to the supply. The supply can be a battery, a transformer, a generator, or it could be a natural source like lightning. It may not be readily apparent, but when lightning flows from cloud to earth or from earth to cloud, it is returning to its source. If you think of the earth and its atmosphere as the source, then that makes sense.Electricity will not flow through any path that does not allow it to return to its source. For example, when a bird lands on a high-voltage transmission line, there is no path through the bird that takes the current back to the supply; therefore, the bird will not get shocked. The drawing in Figure 2.2 illustrates that. The symbol on the left indicates an alternating current (AC) supply, and a bird has landed on the conductor, but there is no path through the bird that can carry current back to the supply; therefore, the bird in this illustration will be safe.
3D modeling and measuring of tire-pavement contact pressure
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
E.Y. Manyo, I. Leandry, B. Picoux, P. Reynaud, F. Allou, C. Petit
Basic principle of this optical technique consists in projecting a pattern of fringes on the specimen and in recording an image of the deformed fringes by specimen surface with another point of view. In fact, a pattern of fringes is generated by acomputer and projected on the specimen surface by the video projector. The projected fringes are deformed by the tested surface and images of those fringes are recorded by a CCD camera. Those images are then analysed in order to obtain the projected pattern phase. Roughness information is contained in this pattern phase. In this study, the fringe intensity is given by: () I(θ)=I0⋅(1+cos(θ+φ))
The Transmission and Reproduction of Audio Post Production Material
Published in Hilary Wyatt, Tim Amyes, Audio Post Production for Television and Film, 2013
The images produced by the best modern video projectors today are almost indistinguishable in quality from the images thrown by a film projector. Images must have high definition, excellent contrast, good colour rendering and be bright; to produce all this from a video projector requires state-of-the-art technology (which simple mechanical film projectors do not need!). Video images often suffer from insufficient illumination; lamp technology is available to create the necessary lumens, but the heat the lamp produces is excessive. A single 35-mm projection frame stays in front of the lamp for just 0.041 seconds. In the video projector the device producing the picture is held in front of the lamp permanently. Digital Micromirror Devices (DMD) provide a solution to heat problems. Light is not passed through the device, as with a liquid crystal display (LCD) device, but is reflected through a multitude of small, coloured metal mirrors, which in turn reflect the heat when light is reflected onto the screen. Lamp life is unfortunately short, and the projectors cost about five times more than a comparable film projector.
3D Digital Survey of Iron Tie-Rods in Masonry Buildings: Cross-Sections Analysis and Error Estimation
Published in International Journal of Architectural Heritage, 2019
Carlo Battini, Chiara Calderini, Rita Vecchiattini
The instrumentation used for the survey of tie-rods is a low-cost scanner called SLS-2 and produced by DAVID System Vision GmbH (https://www.david-3d.com/support/david4/introduction), together with its management software DAVID Laser scanner, able to acquire models with an accuracy that reaches 0.05% of the maximum size scanned. In particular, the instrumentation consists of a monochrome CMOS camera, with WXGA resolution (1280x940 pixels), with 25 frames per second and a focal length of 12 mm, a graduated bar, and an Acer K132 video projector. The system, called triangulation, provides for projection, through the projector, of black and white stripes on the surface of the object to be detected, both horizontally and vertically; at the same time, the camera acquires these stripes that are deformed by the geometry of the portion of scanned surface. Before each survey campaign, after the base components are assembled (camera, projector, and graduated bar), the system is calibrated using the calibration panel contained in the SLS-2 package that allows calculation of the focal length, the radial correction coefficient k1, the left scale factor and the coordinates of the main point cx and cy (Figure 4). This operation allows to define the precision that the survey must reach. In fact, knowing the resolution of the camera, increasing the distance from the instrumentation, the resolution and the accuracy of the acquisition decrease.
The development of perceptual-cognitive skills in youth volleyball players
Published in Journal of Sports Sciences, 2021
Silke De Waelle, Griet Warlop, Matthieu Lenoir, Simon J. Bennett, Frederik J.A. Deconinck
The video clips were back projected, using an LED video projector (LG PH550G, Seoul, South Korea) with HD resolution onto a 1.07 m (w) x 0.6 m (l) projection screen. The projector was placed 1.5 m from the screen on a table, while the subjects were placed behind the table at 2.00 m from the screen (see Figure 6). To facilitate immersion in the volleyball game that was displayed, participants would be standing up for the anticipation and decision-making tests. However, to enable easy writing in the pattern recall test, participants were seated at the table for that test. The participants’ responses for the anticipation and decision-making tests were recorded using a standard Dell keyboard with a wired USB connection. OpenSesame software was used to display the videos and record the participants responses (Mathôt et al., 2012). This software is designed specifically for behavioural experiments and allows for efficient stimulus presentation with sub-millisecond timing.2All standard keyboards are subject to timing lag. According to Damian (2010) the average lag caused by keyboards in scientific experiments is around 30 ms, and Damian (2010) concluded that the variation in human performance is considerably larger than any variation due to response device imprecision. Software packages can also cause lag, and for OpenSesame, Bridges et al. (2020) showed that, for onset of visual stimuli and response times, timing lag in OpenSesame is minimal (3.85 ± 0.7 ms for visual onset and 8.27 ± 1.22 ms for response time measurement).
The reduction of low-income housing stigma with facade features; low- and medium-sized cities
Published in Architectural Engineering and Design Management, 2023
Mehrnaz Ramzanpour, Ali Sharghi, Abdolmajid Nourtaghani, Bahram Saleh Sedghpour
Each slide has an image (in size of 99×110 cm and at a 300-dpi resolution) in the gray background via the video projector on the screen with the dimension of 1.80×1.80 meters, in front of the participant with a distance of 2.5 meters (video projector, NEC M-350XG). First, the purpose and process of the survey were explained to each participant. In the experiment, participants were asked to rate the facade separately, assuming that LIH was to be built in their city. This process was repeated for all 24 images. There was no time limit for responding to the questions (about 20–25 min for each person). The order of the display of slides was random. The research steps are indicated in Figure 2.