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Flow Switches
Published in Béla G. Lipták, Flow Measurement, 2020
Microwave switches detect the flow of solids by detecting motion, or the absence of it. In the microwave-type motion detector the transducer emits a 24 GHz signal into the flowing solid stream and analyzes the reflected frequency (Doppler effect) to determine the speed of the object that reflected it. The sensitivity of the solids flow switch is adjustable, so that it might be used to detect flow/no-flow or trip at a velocity as low as 6 in./min (15 cm/min) when the pipe is full or at a velocity of one particle every 5 seconds in a free-falling gravity flow system. Units are available in aluminum or stainless steel and can be connected to a pipe by a coupling or flange (Figure 6g) or can look through windows or nonmetallic walls without any openings. The units are intrinsically safe and can be used at working pressures up to 15 PSIG (1 bar). The switch can also observe motion at a distance of several feet from the detector and can tolerate 0.5 in. of nonconductive coating buildup or 0.1 in. of conductive coating buildup.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Many other sensors are used for position, displacement, and proximity sensing. Most of these sensors can also be used as motion detectors by the use of suitable signal processing and display techniques. Some of these sensors include: Position-sensitive detectorsProximity sensors with polarized lightPhoto beam sensorsFiber optic sensorsGrating sensors such as encoded discsUltrasonic sensorsMicrowave and Doppler radar sensors
Human Occupancy Detectors
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
There are two types of the IR motion detectors: passive and active. Here we briefly overview the passive passive infrared (PIR) detectors as most popular for the security and energy management systems. The PIR sensing element is responsive to mid- and far-IR radiation within a spectral range from approximately 4 to 20 μm where most of the thermal power emanated by humans is concentrated (body surface temperatures ranging from about 28°C and up). There are three types of the sensing elements that are potentially useful for that detector: bolometers, thermopiles, and pyroelectrics; however, the pyroelectric elements are used almost exclusively for motion detection thanks to their simplicity, low cost, high responsivity, and broad dynamic range. Let’s see how a pyroelectric may be employed in a practical motion sensor design.
Autonomous monitoring framework for resource-constrained environments
Published in Cyber-Physical Systems, 2018
Sajid Nazir, Hassan Hamdoun, Fabio Verdicchio, Gorry Fairhurst
The motion detector is highly sensitive to ensure nearly all targets passing in the area of interest are detected. We found that in only two cases the motion sensor was not triggered, despite a target being visible in the background of a time-lapse image; this was due to the animal being too far to trigger the PIR sensor. The downside of a highly sensitive detector is that it could be triggered by moving vegetation, as many sensor-triggered images did not contain an actual target. However, a difference image had white blobs corresponding to animal location. With no animal or other moving object in the scene, this difference would be a totally black image. In all such cases, image processing on the captured images eliminates all false positives (47 images) without discarding any relevant information (19 images).
Design reviews on a multipurpose power sockets for different applications
Published in Cogent Engineering, 2018
Chin jie Wong, Umar Nirmal, Sharmeeni Murugan
A motion detector sensor is a device that detects the objects that are in motion, particularly human. The appliance is used to together with an integrated system to automatically perform an order or command when the motion of user is detected. Passive infrared sensor and occupancy sensor are examples of motion detector sensor. A passive infrared sensor (PIR sensor) is an electronic device that measures the infrared ray (IR) that is radiating from the particular object that is either in motion or in stand still position. When an object passes through a certain compound, said a wall, the temperature at that point in the sensor’s viewpoint will rise from room temperature to body temperature. The temperature falls back to room temperature when the object passes by the area. The sensor converts the resulting change in the incoming IR into output voltage which will trigger the detection. The PIR sensor can also detect objects with similar temperature but different surface characteristics as the surface may have different IR emission pattern. While occupancy sensor consists of various indoor motion detecting devices used to notice the presence of a person in a room or space.
Aging and technology: understanding the issues and creating a base for technology designers
Published in Journal of Medical Engineering & Technology, 2021
Monitoring the environment in which the elders live is important to keep them safe, and sensors are the dominant technology used in this context. According to Bharucha et al. [86], several technologies have been used for this purpose. Motion detectors have been used to check motion and postures and to detect any deviation from the norm. Several other products have been used, such as light sensors, door and window sensors that detect openings, leak and spill sensors to detect liquid spills, glass and leak sensors to detect if a glass was shattered, and electrical usage and water/sewer usage sensors that detect changes in those two utilities. Finally, pressure and force sensors are used to detect pressure.