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Measurement Uncertainty
Published in Stanislaw Zurek, Characterisation of Soft Magnetic Materials Under Rotational Magnetisation, 2017
The base clock accuracy is given as ±0.01%, which at 50 Hz corresponds to 0.005 Hz. Therefore, absolute uncertainty 0.005 Hz can be assumed with a rectangular distribution. (But of course the frequency can be measured directly and then also the specification of the frequency meter will need to be taken into account.)
Load Management Framework in Smart Grids: A Meta-Analysis and Review
Published in IETE Technical Review, 2022
Ernad Jabandžić, Tatjana Konjić, Dženana Tomašević
When measuring, one determines time and location when and where it is performed, as well as metering devices used to conduct the activity. Thirty one per cent papers state that the measurement is performed on the electricity consumer side [112,115–117,123,125,127], while 40% of them state that it is conducted on the residential electricity consumers side [92,99,113,114,118–120,127]. Load measurement and monitoring are performed on the low voltage (LV) distribution substation in 19% of papers [27,121,122,124]. 10% of papers conduct research on distributed generation systems based on measurement on the exit of distributed sources [128,129]. When a time period and frequency are considered, the situation is as follows: 59% of papers talk about the real-time measurement without reporting the sampling intervals [114–116,118,120,123–129], 22% deal with the real time measurement, but with some of the following sampling intervals: 1, 10, 15, 30, or 60 minutes [92,99,112,117,119], 9% of them select measurement on the seasonal basis [121,122], 5% analyse the short time measurements, i.e. two days in different seasons [27], and 5% consider measurement in a 12-month period [113]. Authors in [27,92,99,116–118,120–127] use smart meters when doing the measurement which represent 64% of the literature. The rest of 36% report other devices for measurement purposes (advanced metering infrastructure, ammeter, wattmeter, frequency meter, etc.) [112–115,119,128,129].
Study on the influence of an underground low-light environment on human safety behavior
Published in International Journal of Occupational Safety and Ergonomics, 2022
Jing Li, Zhen Wang, Yaru Qin, Ruikang Qi, Gui Fu, Baochang Li, Lei Yang
It is believed that fatigue is linked to safety behavior. This is because, when tired, people will slow down their thinking and movements and lose concentration, and their coordination and accuracy of movements also decline. As a result, their safety behavior ability will be reduced [23]. Operators feel oppressed in an underground coal mine because of low lighting, noise, dust and narrow channels, and fatigue will cause distraction and sleepiness, which will increase the probability of an accident. Generally, the flash fusion frequency is used to measure human fatigue and the frequency of flash fusion will be reduced with the growth of fatigue. In this article, a BD-II-118 (Beijing qingniaotianqiao Instrument and Equipment Co., Ltd, China) flash fusion frequency meter was used to measure the critical frequency of flash fusion of subjects, as shown in Figure 1. Generally, the frequency of flash fusion will reduce with an increase in fatigue. While the frequency of flash fusion may vary for different individuals, the figure mainly ranges from 30 to 40 Hz [24].
Comparative study between fully tethered and free swimming at different paces of swimming in front crawl
Published in Sports Biomechanics, 2019
Mathias Samson, Tony Monnet, Anthony Bernard, Patrick Lacouture, Laurent David
Experimentations were conducted in a specific pool of the Pprime Institute (Figure 1). The swimmers began by the free swimming tests, and after a complete recovery period (about 15 min) and a period of adaptation, they performed the tethered swimming tests. Before the free swimming test, a dry warm-up was carried out (ten minutes), followed by an in-water warm-up (five minutes). In the free swimming conditions, swimmers have performed three runs at the three characteristic paces of swimming: sprint (corresponding to 50 and 100 m distances), middle-distance (200 and 400 m) and distance (800 and 1500 m) with five minutes of passive recovery between each run. The reader is referred to the article of Samson et al. (2015) to get the details of the free swimming protocol. After a full rest period and a short warm-up period in the water (a few minutes), they performed the tethered swimming tests. The swimmers were tethered with a non-deformable cable fixed on a belt around the pelvic, and connected to an edge of the specific pool (Figure 1). In tethered condition, swimmers swam with arms and legs at a predicted pace (distance, middle-distance and sprint) during 14 strokes without inspiring (to eliminate possible effects of breathing on the swimming). The instructions were given to swim at competition level speed. The measurement of stroke frequency (with a chrono-frequency meter: IHM®, C500 model, France) was an indicator to check if the swimmer was performing the required pace. The measurements were limited to the last 10 strokes. An aquatic stroke begins when the tip of the middle finger of the hand enters into the water and finishes when it exits. Each instant of the entry and the exit of the hand in water were carefully identified using a video system (Basler Cameras, 50 Hz of sampling frequency, Germany) synchronised with the optoelectronic system.