scholarly journals Wireless Passive High-Temperature Sensor Readout System for Rotational-Speed Measurement

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yingping Hong ◽  
Pengyu Jia ◽  
Xihao Guan ◽  
Jijun Xiong ◽  
Wenyi Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Rotational Speed ◽  
Maximum Temperature ◽  
Readout System ◽  
Passive Measurement ◽  
Signal Conversion ◽  
Speed Measurement ◽  
Signal Demodulation ◽  
Characteristic Signal ◽  
Frequency Demodulation

Rotational-speed measurement in harsh environments is an important topic. However, the high rotation results in rapid frequency variations in the signals of a sensor and changes in physical properties under extreme thermal circumstances cause significant difficulties in reading signals. To address this problem, we adopt wireless passive measurement methods to design a special characteristic signal circuit module that achieves precise measurement of rotational speed at high temperatures. The sensor and the readout system include a variable frequency source, a readout antenna, and a radio frequency demodulation circuit. Herein, a demodulation detector of the signal conversion circuit is designed and used in the envelope detection module of the single sideband demodulation method. In addition, a conversion circuit test platform for high-temperature environment sensor signal is developed. From the testing, the output signal demodulation of the sensor was observed under a maximum temperature of 700°C with error less than 0.12%. The new sensor and measurement method do not require physical leads and achieve wireless noncontact accurate measurement of rotational speed at high temperature.

scholarly journals Digital Approach to Rotational Speed Measurement Using an Electrostatic Sensor

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2540 ◽  
Author(s):  
Lin Li ◽  
Hongli Hu ◽  
Yong Qin ◽  
Kaihao Tang
Keyword(s):  
Rotational Speed ◽  
Sampling Rate ◽  
Correlation Method ◽  
Response Speed ◽  
Square Wave ◽  
Signal Conversion ◽  
Speed Measurement ◽  
Auto Correlation ◽  
Relative Errors ◽  
A Charge

In industrial production processes, rotational speed is a key parameter for equipment condition monitoring and fault diagnosis. To achieve rotational speed measurement of rotational equipment under a condition of high temperature and heavy dust, this article proposes a digital approach using an electrostatic sensor. The proposed method utilizes a strip of a predetermined material stuck on the rotational shaft which will accumulate a charge because of the relative motion with the air. Then an electrostatic sensor mounted near the strip is employed to obtain the fluctuating signal related to the rotation of the charged strip. Via a signal conversion circuit, a square wave, the frequency of which equals that of the rotation shaft can be obtained. Having the square wave, the M/T method and T method are adopted to work out the rotational speed. Experiments were conducted on a laboratory-scale test rig to compare the proposed method with the auto-correlation method. The largest relative errors of the auto-correlation method with the sampling rate of 2 ksps, 5 ksps are 3.2% and 1.3%, respectively. The relative errors using digital approaches are both within ±4‰. The linearity of the digital approach combined with the M/T method or T method is also superior to that of the auto-correlation method. The performance of the standard deviations and response speed was also compared and analyzed to show the priority of the digital approach.

Quantitative FM Spectroscopy at High Temperatures: The Detection of 1CH2 behind Shock Waves

2000 ◽  
Vol 214 (12) ◽  
Author(s):  
G. Friedrichs ◽  
H.Gg. Wagner
Keyword(s):  
High Temperature ◽  
Shock Waves ◽  
High Temperatures ◽  
Frequency Modulation ◽  
Modulation Frequency ◽  
Optical Power ◽  
Time Resolved ◽  
Signal Conversion ◽  
High Modulation ◽  
Singlet Methylene

The technique of time resolved frequency modulation (FM) spectroscopy has been shown to provide a very sensitive means to detect small radicals behind shock waves. Features of high temperature FM spectroscopy behind shock waves will be discussed and a general signal conversion procedure to carry out quantitative concentration measurements will be presented.Using a high modulation frequency, a high modulation index and high total optical power, singlet methylene radicals (α

scholarly journals Study on the Stability of the Electrical Connection of High-Temperature Pressure Sensor Based on the Piezoresistive Effect of P-Type SiC

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 216
Author(s):  
Yongwei Li ◽  
Ting Liang ◽  
Cheng Lei ◽  
Qiang Li ◽  
Zhiqiang Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
Extreme Environment ◽  
Maximum Temperature ◽  
Piezoresistive Effect ◽  
Electrical Connection ◽  
Contact Stability ◽  
The Stability ◽  
P Type

In this study, a preparation method for the high-temperature pressure sensor based on the piezoresistive effect of p-type SiC is presented. The varistor with a positive trapezoidal shape was designed and etched innovatively to improve the contact stability between the metal and SiC varistor. Additionally, the excellent ohmic contact was formed by annealing at 950 °C between Ni/Al/Ni/Au and p-type SiC with a doping concentration of 1018cm−3. The aging sensor was tested for varistors in the air of 25 °C–600 °C. The resistance value of the varistors initially decreased and then increased with the increase of temperature and reached the minimum at ~450 °C. It could be calculated that the varistors at ~100 °C exhibited the maximum temperature coefficient of resistance (TCR) of ~−0.35%/°C. The above results indicated that the sensor had a stable electrical connection in the air environment of ≤600 °C. Finally, the encapsulated sensor was subjected to pressure/depressure tests at room temperature. The test results revealed that the sensor output sensitivity was approximately 1.09 mV/V/bar, which is better than other SiC pressure sensors. This study has a great significance for the test of mechanical parameters under the extreme environment of 600 °C.

Study on the Thermo-Hydrodynamic of a Dry Gas Seal in Helium Circulator for High Temperature Gas-Cooled Reactor

2011 ◽  
Author(s):  
Jianshu Lin ◽  
Hong Wang
Keyword(s):  
High Temperature ◽  
Film Flow ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Analysis Method ◽  
Dry Gas Seal ◽  
Safety Requirements ◽  
Simulation Results ◽  
Gas Seals ◽  
High Temperature Gas

A comprehensive analysis method is proposed to resolve the problem of simulating a complex thermo-flow with two kinds of distinct characteristic length in the dry gas seal, and a conjugated simulation of the complicated heat transfer and the gas film flow is carried out by using the commercial CFD software CFX. By using the proposed method, a three dimensional of velocity and pressure field in the gas film flow and the temperature distribution within the sealing rings are investigated for three kinds of film thickness, respectively. A comparison of thermo-hydrodynamics of the dry gas seals is conducted between the sealed gas of air and helium. The latter one is used in a helium circulator for High Temperature Gas-cooled Reactor (HTGR). From comparisons and discussions of a series of simulation results, it will be found that the comprehensive proposal is effective and simulation results are reasonable, and the maximum temperature rise in the dry gas seal is within the acceptable range of HTGR safety requirements.

scholarly journals OPTIMIZATION OF INORGANIC COMPONENTS OF FIRE PROTECTIVE VARNISH FOR WOOD

2021 ◽  
pp. 123-132
Author(s):  
Yu. Tsapko ◽  
◽  
А. Tsapko ◽  
O. Bondarenko ◽  
V. Lomaha ◽  
...  
Keyword(s):  
High Temperature ◽  
Fire Retardant ◽  
Protective Layer ◽  
Combustion Products ◽  
Wood Products ◽  
Maximum Temperature ◽  
Protective Film ◽  
Insulating Layer ◽  
Combustible Gases ◽  
Material Studies

Abstract. The processes of creation of fire-retardant varnish for wood consisting of a mixture of inorganic and polymeric substances are investigated in the work. It is established that the optimization of the inorganic component leads to a directional ratio of mineral acids and urea capable of effective fire protection of the material. Studies have shown that at the initial temperature of gaseous combustion products T = 68 °C, when exposed to the radiation panel, the untreated sample ignited after 146 s, the flame spread over the entire surface, instead, the sample fire-protected varnish did not ignite, the maximum temperature was 105 °C. In this case, as evidenced by the results of heat resistance, there is a change in the structure of the protective film of the coating. The thickness of the protective layer increases due to the decomposition of the composition, which leads to inhibition of oxidation in the gas and condensed phase, change the direction of decomposition towards the formation of non-combustible gases and combustible coke residue, reduce material combustion and increase flammability index. The coating under the influence of high temperature promotes the formation of a heat-insulating layer of coke, which prevents burning and the passage of high temperature to the material, which is confirmed by the absence of the process of ignition of fire-retardant wood. Features of braking of process of ignition and distribution of a flame of the wood processed by a varnish which consist in several aspects are established. This is the formation of a heat-insulating layer of coke, which prevents burning and the passage of high temperatures to the material, which is confirmed by the absence of the process of ignition of fire-retardant reeds. This indicates the possibility of targeted control of high temperature transfer processes to organic material through the use of special coatings for wood products.

scholarly journals OVEN OR FIREPLACE? (EXPERIMENTAL FIRINGS OF THE VESSELS)

2015 ◽  
Vol 4 (3) ◽  
pp. 37-55
Author(s):  
Yelena Vitalievna Volkova
Keyword(s):  
High Temperature ◽  
Basic Knowledge ◽  
Maximum Temperature ◽  
Firing Process ◽  
Cow Dung ◽  
Natural Clay ◽  
Analytical Studies

The paper contains the results of the field experimental firings in fireplaces and in ovens made on the basis of Samara pottery experimental expedition (Dr N.P. Salugina is the leader of the expedition) in 2013. The author put forward two goals: one is to discover the basic knowledge on firing process with various kinds of fuel, and second is to find out the specific features to discern the vessels fired in fireplaces from the vessels fired in ovens. 20 vessels were prepared to the experiment. The first 10 pots were made of natural clay and the second 10 vessels were made of pottery paste (clay + grog + cow dung). Five simultaneous firings with various kinds of fuel were organized in fireplace and in oven. The author describes in detail the program, main steps, and maximum temperature of firings, the photos of the vessels, and the results of their analytical studies. After the experiments the author came to the next conclusions: firstly - there are absent the reliable features to distinguish the vessels fired in fireplace and in oven, secondly - there is one dependence between a kind pottery paste and a color of fired vessels and another relation between pottery paste and a degree of high-temperature baking of vessels.

Diurnally Alternating Temperatures Stimulate Sprouting of Purple Nutsedge (Cyperus rotundus) Tubers

Weed Science ◽  
1996 ◽  
Vol 44 (1) ◽  
pp. 122-125 ◽  
Author(s):  
Joel E. Miles ◽  
Roy K. Nishimoto ◽  
Osamu Kawabata
Keyword(s):  
High Temperature ◽  
Cyperus Rotundus ◽  
Maximum Temperature ◽  
Temperature Cycle ◽  
Purple Nutsedge ◽  
Tuber Temperature ◽  
Tuber Sprouting ◽  
Alternating Temperature ◽  
Increasing Temperature ◽  
Temperature Responses

Experiments were conducted to determine the response of purple nutsedge tuber sprouting to diurnally alternating temperature. These experiments compared the response to alternating and constant temperatures and determined the effect of the amplitude of alternation and time of exposure to the maximum temperature. Tuber sprouting was more rapid and complete with alternating temperatures than with constant temperatures. Increasing temperature fluctuation from 0 to 6 C for 12 h daily linearly increased total tuber sprouting. As little as 30 min exposure to high temperature per day provided nearly the same level of sprouting as a 12 h alternating temperature cycle. This phenomenon should be considered when conducting studies to describe tuber temperature responses or when predicting tuber sprouting and emergence.

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