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D.c. transients
Published in John Bird, Electrical and Electronic Principles and Technology, 2017
The internal workings of a camera flash are an example of the application of C–R circuits. When a camera is first switched on, a battery slowly charges a capacitor to its full potential via a C–R circuit. When the capacitor is fully charged, an indicator (red light) typically lets the photographer know that the flash is ready for use. Pressing the shutterbutton quickly discharges the capacitor through the flash (i.e. a resistor). The current from the capacitor is responsible for the bright light that is emitted. The flash rapidly draws current in order to emit the bright light. The capacitor must then be discharged before the flash can be used again.
Design Recommendations towards Developing a Smartphone-Based Point-of-Care Tool for Rural Bangladeshi Users
Published in International Journal of Human–Computer Interaction, 2023
Md Kamrul Hasan, Devansh Saxena, Yakin Rubaiat, Sheikh Iqbal Ahamed, Shion Guha
The BEst app included some basic interfaces for the participants. The login page allowed participants to enter valid credentials (id and password). If unregistered, the app directed the user to register with gender, age, name, and password where the name was optional (Figure A1(a)). After successfully logging into the app, the user could select a LED light source name they wanted to use. Then they attached the LED box (e.g., 850 nm) with the index finger (Figure A1(c–f)) and recorded a fingertip video. After one video, the next fingertip video can be recorded, returning to this interface. The option “Camera flash” was selected when only camera flash was used while recording a video. In other cases, if a user selected, for example, 940 nm, only the LED box lights were available for video recording. Attaching a LED box and choosing a light source, participants pressed the “Start Recording” button (Figure A1(c–f)). The video recording module included two buttons and three labels. Among the two buttons, the “Cancel” button could stop a video recording at any moment, and the “Submit” button showed a recorded video was transferred to a cloud server for further (animated) processing.
A Comprehensive Survey on the Detection of Diabetic Retinopathy
Published in IETE Journal of Research, 2022
Jackman and Webster [5] first published photographs of the retina in 1886. The scientist Frederick Dimmer [6] developed the first fundus camera. This was the only developed camera at that time, which was considerably large. J. W. Nordenson created the first modern fundus camera in 1925, which was made available commercially by Carl Zeiss Company in 1926 with a 10° field of view. In 1953, the camera was available with an electronic flash. In the late 1960s, scientists invented the first photographic technique. This imaging technique came with fluorescein retinal angiography. Novotny and D. L. Alvis [7] published their fluorescein angiography (FA) technique on human eyes in 1961. They were later considered the originators of this imaging modality. FA has become a base for diagnosing, managing and treating retinal vascular diseases. A fundus camera was designed to improve the field of view. Pomerantzeff [8] proposed the Equator-Plus camera. This was the only wide-angle camera with a 148° field of view.
Visualization and size-measurement of droplets generated by Flow Blurring® in a high-pressure environment
Published in Aerosol Science and Technology, 2018
Luis B. Modesto-López, Alfonso M. Gañán-Calvo
An ultra-high speed Shimadzu video camera (HPV-2), capable of recording up to 106 frames-per-second (fps), was focused through one of the sapphire windows, and illuminated with a high-intensity flash placed on the opposite side (Figure 1b). The flash was synchronized with the video camera through an external trigger. The camera began recording 1 ms after the trigger was manually switched on. DI water or ethanol was fed to the FB nozzle with a Shimadzu high-performance liquid chromatography (HPLC) pump (model LC-10AD). The gas inlet pressure (Po) and chamber pressure (Pi) were monitored with digital, high-pressure WIKA manometers capable of measuring up to 10 MPa (model CPG1000). Additional gas was supplied through the ‘corona’ around the FB nozzle (see previous subsection), to increase the chamber pressure up to a desired value. The gas inlet pressure, Po, was varied in the range 1.2–5 MPa and, the chamber pressure, Pi, was maintained from 200 kPa to 3 MPa below Po, as indicated in each set of measurements. Typical liquid flow rates, Q, used in this work were 0.3 and 0.5 mL/min (low range), 1 mL/min (medium range), and 5 mL/min (high range).