Study on Human Temperature Measurement by Infrared Thermography

Increased temperature in humans is one of symptoms of infectious diseases. Infrared thermography is a popular method for measuring temperature as it offers fast and non-contact temperature measurement. However, and despite many advantages, its real accuracy for human temperature measurement is not sufficient in many cases. This study was focused on a statistical evaluation of human temperature measurement reliability. The goal of the experiment was to find limitations of thermography at near-laboratory conditions. More than 300 measurements were made simultaneously by a thermography and an arm-pit thermometer on a closed group of persons during several months. The results showed that standard deviations of the performed armpit and thermographic temperature measurement were about 0.15 and 0.36 °C, respectively, but that a temperature shift and a dependence on ambient conditions can occur due to the used experimental configuration.

Design and Research of Non-contact Temperature Measurement and Identity Recognition System

With the rapid spread of the new crown epidemic, prevention of the epidemic has become an important task in daily life. As of now, the cumulative number of confirmed cases in the world has exceeded 150 million, and the epidemic prevention situation is very serious. In the face of the spread of the epidemic, effective temperature measurement, mask recognition, and face recognition are necessary for mobile personnel. Traditional methods such as the deployment of Raspberry Pi, windows platform, etc. can better meet the above requirements, but there are disadvantages such as low number of recognition frames, low accuracy, and bulky equipment. Due to the large market demand, the cost of the chip has also risen. If the above-mentioned functions are deployed according to the traditional method, the cost is relatively high, which increases the economic pressure on small and medium-sized enterprises. The main work of this research is to solve related functions through a processor Kendryte K210 based on the open source instruction set RISC-V. So as to realize a portable and low-cost non-contact temperature measuring device. The paper introduces a low-cost solution based on K210 on the basis of comprehensive discussion of multi-party implementation methods. Based on this processor, the face recognition and mask recognition functions based on YOLOv2 training are deployed through its machine vision and machine hearing capabilities. The temperature is measured by an external MLX90614 sensor; the serial port screen and the voice module JQ8400 are used for user interaction, which meets the guidance of users to the greatest extent. In the design of the hardware circuit, a lithium battery charging and boosting mobile power board based on MH-CD42 is designed. The user can supply power through an external lithium battery to realize the portability of the system.

Uncertainty of Thermographic Temperature Measurement with an Additional close-up Lens

The thermographic temperature measurement is burdened with uncertainty. This non-contact temperature measurement method makes it possible to measure the temperature of the electrical device under load. When the observed object is small (a few square millimeters) the spatial resolution of the thermographic cameras is often insufficient. In this case, the use of the additional macro lens is needed. After using an additional lens, the uncertainty of the thermographic measurement is different from the uncertainty of thermographic measurement without an additional lens. The values of the uncertainty contributions depend on the conditions during the measurement and the used methodology. The authors constructed an uncertainty budget of thermographic temperature measurement with an additional macro lens, based on EA-4/02 (European Accreditation publications). The uncertainty contributions were also calculated. On the basis of the calculated values of the uncertainty contributions, it was determined which factor had the greatest impact on the value of the thermographic temperature measurement with an additional lens.

Effect of Micro-Textured Surfaces and Sliding Speed on the Lubrication Mechanism and Friction-Wear Characteristics of CF/PEEK Rubbing against 316L Stainless Steel under Seawater Lubrication

In this work, the lubrication mechanism and friction-wear characteristics of the friction pair between carbon-fiber-reinforced polyether ether ketone (CF/PPEK) and 316L stainless steel with a micro-hemispherical pit textured surface at different sliding speeds under seawater lubrication were studied through numerical simulation and experimental investigation. The study results indicate that the seawater moves following the sliding direction of the upper specimen, forms a vortex ring flow in the hemispherical pit of the bottom specimen, uses the convergent gap to generate a hydrodynamic effect, produces the bearing capacity, and realizes fluid lubrication. The hemispherical pit diminishes the abrasive wear during the friction process by storing the wear debris, and the main wear forms of the hemispherical-pit surface friction pair are oxidative wear and adhesive wear. The friction coefficient of the hemispherical-pit surface friction pair is 0.018–0.027, the specimen contact temperature is 40.2–55.1 °C, and it is always in the hydrodynamic lubrication state in a rotation speed ranging from 1000 r/min to 1750 r/min. As the sliding speed increases, the specimen contact temperature climbs, and the oxidation reaction gradually becomes full. Oxidative wear and adhesive wear alternately play a dominant role in the friction, and the wear rate first decreases and then increases sharply.

Effect of contact temperature, normal load and dry sliding velocity on the coefficient of friction and wear behavior of nickel based super alloy

Purpose The purpose of the present paper aims to, study the coefficient of friction and wear behavior of nickel based super alloys used in manufacturing of gas and steam turbine blades. In present paper, parametric study focuses on normal load, dry sliding velocity and contact temperature influence on coefficient of friction and wear of a nickel based super alloy material. Design/methodology/approach Experimental investigation is carried out to know the effect of varying load at constant sliding velocity and varying sliding velocity at constant load on coefficient of friction and wear behavior of nickel based super alloy material. The experiments are carried out on a nickel based super alloy material using pin on disk apparatus by load ranging from 30 N to 90 N and sliding velocity from 1.34 m/s to 2.67 m/s. The contact temperature between pin and disk is measured using K-type thermocouple for all test conditions to know effect of contact temperature on coefficient of friction and wear behavior of nickel based super alloy material. Analytical calculations are carried out to find wear rate and wear coefficient of the test specimen and are compared with experimental results for validation of experimental setup. Regression equations are generated from experimental results to estimate coefficient of friction and wear in the range of test conditions. Findings From the experimental results, it is observed that by increasing the normal load or sliding velocity, the contact temperature between the pin and disk increases, the coefficient of friction decreases and wear increases. Analysis of variance (ANOVA) is used to study the influence of individual parameters like normal load, dry sliding speed and sliding distance on the coefficient of friction and wear of nickel based super alloy material. Originality/value This is the first time to study effect of contact temperature on the coefficient of friction and wear behavior of nickel-based super alloy used for gas and steam turbine blades. Separate regression equations have been developed to determine the coefficient of friction and wear for the entire range of speed of gas turbine blades made of nickel based super alloy. The regression equations are also validated against experimental results.

Scuffing load capacity calculation of worm gears

Worm gears with wheels of harder materials, such as cast iron or steel, are often prone to the damage type scuffing, which can cause a sudden and rapid failure of the gear box. Contact temperature is a suitable criterion to determine the scuffing safety for other types of gears. However, for worm gears, a scuffing load capacity calculation is not available at the moment. This paper presents a numerical temperature simulation for worm gears that considers transient multidimensional heat transfer and local frictional loading due to the contact. Based on the results of this simulation, this paper derives a simplified calculation of worm gear contact temperatures. The calculation only contains input parameters that are already part of current standards. Its result, the contact temperature of worm gears, can be used to rate the scuffing load capacity.