Non-cooled infrared thermal imager is the most widely used instrument for infrared temperature measurement. Sometimes the field environment is different from the correctional environment, and because the off-site environment is unpredictable, the original temperature measurement software is not enough to represent the off-site environment. Therefore, it is necessary to investigate the effect of self-radiation on measurement accuracy of the tested object under the condition of changeable off-site environment. In this study, the relationship between the gray value of infrared image and the change of blackbody temperature, environmental temperature and the temperature of infrared thermal imager are deduced by experimental method. A model is established and solved to reduce the radiation effect of infrared thermal imager on the accuracy of infrared temperature measurement.
Abstract With the gradual development of integrated circuits to thin, high-performance and versatile of electronic products is becoming more and more powerful, and its integration and assembly density continue to improve, which will lead to the increase of its working power consumption and heat. If not timely treatment of heat dissipation problems, which will lead to heat concentration in the diode PN junction, it will reduce the service life of LED lights, and in severe cases, it will even burn the LED device. Therefore, it is crucial to improve heat dissipation efficiency of LED and reduce the junction temperature of chip. An LED structure with aluminum material and an LED structure with graphene material are analyzed by finite element method to study the heat dissipation efficiency of the graphene material. The results reveal that the heat dissipation effect of high conductivity graphene composites provides a convenient evaluation method for the subsequent use of the new materials. The research in this paper shows that the software simulation method can effectively analyze the thermal conductivity of practical engineering applications.
Fever is an important clinical manifestation of new coronavirus pneumonia. In public health emergencies, it is necessary to start fever screening to control the rapid spread of influenza. The measurement and calibration technology of infrared body temperature screening instrument has been developed in recent years, and there are still shortcomings in the field use of infrared screening instrument. In order to fully understand the performance parameters of infrared screening instrument, further improve the performance of equipment and establish a unified reference standards. This study analysis and investigates the test results and performance parameters of multiple screening machines, improving the standardization and effectiveness of fever screening. The results indicate that blackbody can effectively reduce the error, avoid the appearance of larger error, large temperature fluctuation, and restrain the phenomenon of temperature drift to a certain extent.
Infrared temperature measurement has a wide range and more applications, due to infrared temperature measurement does not need to contact with the object under test. However, the accuracy of infrared temperature measurement is difficult to reach a satisfactory degree, which limits the development and application of infrared temperature measurement method. This study explores how the atmospheric transmittance affects the temperature measurement accuracy of infrared thermal imager. Based on the composition of atmosphere, the major reason affecting atmospheric transmittance have been found. Meanwhile, according to the influence of water vapor and carbon dioxide absorption, aerosol, atmospheric molecule and other suspended particles, attenuation of atmospheric transmittance caused by complex weather conditions, such as rain and snow. Atmospheric transmission model is proposed, and the theoretical formula for calculating atmospheric transmittance is obtained.
Unilateral external fixators are commonly used to stabilize the fractured tibia bone. Compared to static fixation, axial dynamization has been shown in previous studies to promote callus formation, improve bone healing at fracture sites, and non-axial movements are not conductive to the bone healing and remodeling. In the later stage of fracture correction, patients can bear a certain load and can realize walking and other movements. Gait motion is the active axial dynamic motion. However, it is still unknown how the displacement change at the fracture site during gait movement motion. So the aim of this study is to use transient dynamic finite element method to simulate the actual walking gait process of the human body based on two unilateral fixators. The results reveal that compared Dyna-extor fixator, the Orthofix fixator has a better stability and flexibility during active dynamization motion. This study helps clinicians to plan and execute to training patients, meanwhile facilitates appro priate application of fixators to achieve either active or controlled axial dynamic movement, so that the orthopedist has a better understanding of the biomechanical environment at the fracture site.
Dry block furnaces are widely used in on-site measurement and calibration of food, petrochemical, pharmaceutical, semiconductor, and other manufacturing enterprises. The accuracy of dry-block furnace temperature measurement has always been a problem for temperature calibrator. The research on the dry-block furnace mainly focuses on the stability measurement, the on-site temperature calibration method, the temperature distribution uniformity and so on. Therefore, the axial temperature distribution of dry-block furnace is an important factor affecting its accuracy. In this study, the dry-block furnace (Const 660 produced in China) is selected as the research object to study the relationship between calibration temperature and axial temperature distribution of dry well furnace by experimental method. The results found that from the bottom of the furnace to the wellhead side, the temperature probe insertion depth should be as close as possible to the bottom of the well, and the closer the calibration temperature is to the ambient temperature, the higher the accuracy of the temperature measurement. The study provides more comprehensive and reliable experimental data for the application of dry-block furnace in field temperature calibration, so as to improve the accuracy of temperature measurement and better application of dry block furnace.
Abstract With the wide application and rapid development of infrared temperature measurement, which has attracted wide spread interest in the field of non-contact temperature measurement due to its unique advantages. Measurement of the real temperature of the measured object is an important task in many disciplines, especially critical and difficult for the non-contact measurement. However, the accuracy of the infrared thermography technique is difficult to reach a satisfactory level, and cannot meet the requirements of high accuracy, due to the emissivity cannot be determined in outdoor environments. It is very meaningful to determinate the emissivity and accurate temperature of the object in outdoor heterogeneous environments. The influence of external environmental factors on the object surface emissivity are analyzed in this study, which is very important to improve the measurement accuracy of the infrared thermal imaging instrument. This study reveals that the increased temperature will lead in the increase of the emissivity of nonmetallic materials first and then decreases slowly. In addition, as the ambient temperature higher, the emission rate of non-metallic object becomes smaller.
Dry block furnaces are widely used in on-site measurement and calibration of food, petrochemical, pharmaceutical, semiconductor, and other manufacturing enterprises for their advantages such as pollution-free, simple operation, easy to carry, fast rise and fall, and wide usable temperature range. The accuracy of dry-block furnace temperature measurement is always a problem for calibrator. The stability of dry-block furnace is an important factor affecting its accuracy. In conventional dry block calibrators, the drift of the internal reference thermometer and temperature gradients in the normalization block are the main contributors to the accuracy. However, the experimental comparison of the stability of the different brands dry-block furnace at different calibration temperatures is rare. we carry out validation and evaluation project to evaluate the stability of dry-block furnaces of two brands at home and abroad, the relationship between calibration temperature and stability of dry well furnace is analyzed by experiments. The results show that the overall stability of RTC158 is better than that of Const660. The measurement accuracy of RTC158 is better than that of Const660. We hope that this experiment can provide more comprehensive and reliable experimental data for the application of dry well furnace in field temperature calibration, so as to improve the accuracy of temperature measurement.
Abstract The dry block temperature calibrator uses air as the calibration medium with small volume and light weight, and therefore is widely applied in field calibration work. With the improvement and vigorous development of the technology of domestic instruments, the technology of domestic dry body furnace is also developing rapidly. Whether the performance of domestic dry block temperature calibrator is better than the foreign instruments, this question is not very clear yet. Therefore, this study focuses on the comparative analysis of the performance parameters of the two dry-type temperature calibrators of Foreign dry furnace-RTC158 and domestic dry furnace-Const660, such as temperature deviation, temperature volatility, axial deviation, and radial deviation. The results reveal that the comprehensive performance of domestic instrument-Const660 is better than foreign instrument-RTC158.
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