scholarly journals A Fast-Response Calorimeter with Dynamic Corrections for Transient Heat Transfer Measurements

2020 ◽  
Vol 10 (17) ◽  
pp. 6143
Author(s):  
Shizhong Zhang ◽  
Qiu Wang ◽  
Jinping Li ◽  
Xiaoyuan Zhang ◽  
Hong Chen
Keyword(s):  
Heat Dissipation ◽  
Fast Response ◽  
Correction Method ◽  
Shock Tunnel ◽  
Test Time ◽  
Correction Coefficient ◽  
Filling Material ◽  
Dynamic Correction ◽  
Detonation Shock ◽  
Measurement Deviation

Robust fast-response transient calorimeters with novel calorimeter elements have attracted the attention of researchers as new synthetic materials have been developed. This sensor uses diamonds as the calorimeter element, and a platinum film resistance is sputtered on the back to measure the temperature. The surface heat flux is obtained based on the calorimetric principle. The sensor has the advantages of high sensitivity and not being prone to erosion. However, non-ideal conditions, such as heat dissipation from the calorimeter element to the surroundings, can lead to measurement deviation and result in challenges for sensor miniaturization. In this study, a novel transient calorimeter (NTC) with two different sizes was developed using air or epoxy as the back-filling material. Numerical simulations were conducted to explain the complex heat exchange between the calorimeter element and its surroundings, which showed that it deviated from the assumption of an ideal calorimeter sensor. Accordingly, a dynamic correction method was proposed to compensate for the energy loss from the backside of the calorimeter element. The numerical results showed that the dynamic correction method significantly improved the measurement deviation, and the relative error was within 2.3% if the test time was smaller than 12 ms in the simulated cases. Detonation shock tunnel experiments confirmed the results of the dynamic correction method and demonstrated a practical method to obtain the dynamic correction coefficient. The accuracy and feasibility of the dynamic correction method were verified in a single detonation shock tunnel and under shock tube conditions. The NTC calorimeter exhibited good repeatability in all experiments.

Aerodynamic Drag Measurement in a High-Enthalpy Shock Tunnel

2018 ◽  
Author(s):  
Yunpeng Wang ◽  
Zonglin Jiang ◽  
Honghui Teng
Keyword(s):  
Natural Frequencies ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Shock Tunnel ◽  
Test Time ◽  
Test Duration ◽  
Flow State ◽  
High Enthalpy

Shock tunnels create very high temperature and pressure in the nozzle plenum and flight velocities up to Mach 20 can be simulated for aerodynamic testing of chemically reacting flows. However, this application is limited due to milliseconds of its test duration (generally 500 μs–20 ms). For the force test in the conventional hypersonic shock tunnel, because of the instantaneous flowfield and the short test time [1–4], the mechanical vibration of the model-balance-support (MBS) system occurs and cannot be damped during a shock tunnel run. The inertial forces lead to low frequency vibrations of the model and its motion cannot be addressed through digital filtering. This implies restriction on the model’s size and mass as its natural frequencies are inversely proportional the length scale of the model. As to the MBS system, sometimes, the lowest natural frequency of 1 kHz is required for the test time of typically 5 ms in order to get better measurement results [2]. The higher the natural frequencies, the better the justification for the neglected acceleration compensation. However, that is very harsh conditions to design a high-stiffness MBS structure, particularly a drag balance. Therefore, it is very hard to carried out the aerodynamic force test using traditional wind tunnel balances in the shock tunnel, though its test flow state with the high-enthalpy is closer to the real flight condition.

scholarly journals Performance of the FMI cosine error correction method for the Brewer spectral UV measurements

2018 ◽  
Vol 11 (9) ◽  
pp. 5167-5180 ◽  
Author(s):  
Kaisa Lakkala ◽  
Antti Arola ◽  
Julian Gröbner ◽  
Sergio Fabian León-Luis ◽  
Alberto Redondas ◽  
...  
Keyword(s):  
Error Correction ◽  
Correction Method ◽  
Uv Spectra ◽  
Correction Coefficient ◽  
Finnish Meteorological Institute ◽  
Angular Response ◽  
Error Correction Method ◽  
Radiation Distribution ◽  
Rapid Changes ◽  
Relative Differences

Abstract. Non-ideal angular response of a spectroradiometer is a well-known error source of spectral UV measurements and for that reason instrument specific cosine error correction is applied. In this paper, the performance of the cosine error correction method of Brewer spectral UV measurements in use at the Finnish Meteorological Institute (FMI) is studied. Ideally, the correction depends on the actual sky radiation distribution, which can change even during one spectral scan due to rapid changes in cloudiness. The FMI method has been developed to take into account the changes in the ratio of direct to diffuse sky radiation and it derives a correction coefficient for each measured wavelength. Measurements of five Brewers were corrected for the cosine error and the results were compared to the reference travelling spectroradiometer (QASUME). Measurements were performed during the RBCC-E (Regional Brewer Calibration Center – Europe) X Campaign held at El Arenosillo, Huelva (37∘ N, 7∘ W), Spain, in 2015. In addition, results of site audits of FMI's Brewers in Sodankylä (67∘ N, 27∘ E) and Jokioinen (61∘ N, 24∘ E) during 2002–2014 were studied. The results show that the spectral cosine error correction varied between 4 and 14 %. After that the correction was applied to Brewer UV spectra the relative differences between the QASUME and the Brewer diminished even by 10 %. The study confirms that the method, originally developed for measurements at high latitudes, can be used at mid-latitudes as well. The method is applicable to other Brewers as far as the required input parameters, i.e. total ozone, aerosol information, albedo, instrument specific angular response and slit function are available.

scholarly journals Terrain-Based Shadow Correction Method for Assessing Supraglacial Features on the Greenland Ice Sheet

2021 ◽  
Vol 2 ◽  
Author(s):  
Sasha. Z. Leidman ◽  
Åsa K. Rennermalm ◽  
Richard G. Lathrop ◽  
Matthew. G. Cooper
Keyword(s):  
Land Surface ◽  
Greenland Ice Sheet ◽  
Correction Method ◽  
Correction Coefficient ◽  
Digital Elevation ◽  
Aerial Vehicle ◽  
Sediment Cover ◽  
Elevation Model ◽  
Uav Images ◽  
Gis Software

The presence of shadows in remotely sensed images can reduce the accuracy of land surface classifications. Commonly used methods for removing shadows often use multi-spectral image analysis techniques that perform poorly for dark objects, complex geometric models, or shaded relief methods that do not account for shadows cast on adjacent terrain. Here we present a new method of removing topographic shadows using readily available GIS software. The method corrects for cast shadows, reduces the amount of over-correction, and can be performed on imagery of any spectral resolution. We demonstrate this method using imagery collected with an uncrewed aerial vehicle (UAV) over a supraglacial stream catchment in southwest Greenland. The structure-from-motion digital elevation model showed highly variable topography resulting in substantial shadowing and variable reflectance values for similar surface types. The distribution of bare ice, sediment, and water within the catchment was determined using a supervised classification scheme applied to the corrected and original UAV images. The correction resulted in an insignificant change in overall classification accuracy, however, visual inspection showed that the corrected classification more closely followed the expected distribution of classes indicating that shadow correction can aid in identification of glaciological features hidden within shadowed regions. Shadow correction also caused a substantial decrease in the areal coverage of dark sediment. Sediment cover was highly dependent on the degree of shadow correction (k coefficient), yet, for a correction coefficient optimized to maximize shadow brightness without over-exposing illuminated surfaces, terrain correction resulted in a 49% decrease in the area covered by sediment and a 29% increase in the area covered by water. Shadow correction therefore reduces the overestimation of the dark surface coverage due to shadowing and is a useful tool for investigating supraglacial processes and land cover change over a wide variety of complex terrain.

scholarly journals Coaxial Thermocouples for Heat Transfer Measurements in Long-Duration High Enthalpy Flows

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5254
Author(s):  
Shizhong Zhang ◽  
Qiu Wang ◽  
Jinping Li ◽  
Xiaoyuan Zhang ◽  
Hong Chen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Thermal Effusivity ◽  
Fast Response ◽  
Test Time ◽  
Physical Parameters ◽  
Fourier Number ◽  
High Enthalpy ◽  
Long Duration

Coaxial thermocouples have the advantages of fast response and good durability. They are widely used for heat transfer measurements in transient facilities, and researchers have also considered their use for long-duration heat transfer measurements. However, the model thickness, transverse heat transfer, and changes in the physical parameters of the materials with increasing temperature influence the accuracy of heat transfer measurements. A numerical analysis of coaxial thermocouples is conducted to determine the above influences on the measurement deviation. The minimum deviation is obtained if the thermal effusivity of chromel that changes with the surface temperature is used to derive the heat flux from the surface temperature. The deviation of the heat flux is less than 5.5% when the Fourier number is smaller than 0.255 and 10% when the Fourier number is smaller than 0.520. The results provide guidance for the design of test models and coaxial thermocouples in long-duration heat transfer measurements. The numerical calculation results are verified by a laser radiation heating experiment, and heat transfer measurements using coaxial thermocouples in an arc tunnel with a test time of several seconds are performed.

Research on the Positioning Technology and Attitude Solution Based on STM32

2014 ◽  
Vol 898 ◽  
pp. 910-913
Author(s):  
Hui Can Lin ◽  
Tao Guo ◽  
Yu Shi ◽  
Yang Liu ◽  
Zi Jing Zhong
Keyword(s):  
High Precision ◽  
Linear Prediction ◽  
Fast Response ◽  
Correction Method ◽  
Mems Devices ◽  
Electromagnetic Environment ◽  
Information Monitoring ◽  
Kalman Filter Algorithm ◽  
Suppress Noise ◽  
Attitude Sensor

Aircraft control, the training process to locate the aircraft attitude and heading information monitoring requires high-precision gesture as a feedback input, application STM32F103T8 processor design a combination of positioning technology and attitude sensor acquisition system. Measurement module with low power consumption, fast response and high accuracy, the use of high precision MEMS devices with 32-bit processors STM32F103T8 good data processing capabilities. For sensor characteristics, extended Kalman filter algorithm is designed based on dual quaternion vector correction method, enhanced anti-jamming capability; characteristics of complex electromagnetic environment, an improved forward linear prediction filtering method, processing the received GPS data, improving positioning accuracy. The results show that the proposed method effectively suppress noise, gesture detection, accurate and fast.

scholarly journals Modeling and Analysis of Nonlinear Axial Force Generated by Automotive Drive-shaft Systems Based on Fractal Theory

2021 ◽  
Author(s):  
Huayuan Feng ◽  
Wen-Bin Shangguan
Keyword(s):  
Fractal Theory ◽  
Surface Characteristics ◽  
Correction Method ◽  
Fractal Model ◽  
Drive Shaft ◽  
Correction Coefficient ◽  
Modeling And Analysis ◽  
Shaft System ◽  
Fractal Parameters ◽  
Micro Level

Abstract The nonlinear generated axial force (NGAF) of an automotive drive-shaft system is mainly induced by the tripod joint in the drive-shaft system, which will lead to vibration and noise of a vehicle. On the basis of fractal theory, this paper conducts modeling and analysis of the NGAF from the micro level to study the NGAF more effectively. In order to describe the micro contact and friction states between rollers and tracks inside the tripod joint more accurately, a correction method for correcting the distribution function of asperities between rollers and tracks is proposed. Based on the proposed correction method and a calculation model of the NGAF, a fractal model of the NGAF considering rough surface characteristics is established. The fractal model is mainly related to the fractal parameters, the material parameters, the operating conditions and the correction coefficient of the distribution function of asperities. Using Sobol' global sensitivity analysis method, the first order and overall global sensitivities of the fractal model of the NGAF are subsequently analyzed to determine the influence of the factors on the NGAF. The effectiveness of the fractal model and the analytical method for the NGAF is verified by the experiment and calculation examples. The results show that modeling and analysis of the NGAF considering rough surface characteristics are essential to reveal the relationships between the NGAF and the fractal parameters, the material parameters and the correction coefficient from the micro level, which is helpful for the design and analysis of the NGAF of the drive-shaft system.

Proposal on dynamic correction method for resonance ionization mass spectrometry

LAP 2012 ◽  
2013 ◽  
pp. 47-51
Author(s):  
Takuma Noto ◽  
Hideki Tomita ◽  
Sven Richter ◽  
Fabian Schneider ◽  
Klaus Wendt ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Correction Method ◽  
Ionization Mass Spectrometry ◽  
Resonance Ionization ◽  
Ionization Mass ◽  
Dynamic Correction ◽  
Resonance Ionization Mass Spectrometry

Effect of Mass Added to a Force Transducer on the Dynamic-Force Correction Method

2019 ◽  
Vol 888 ◽  
pp. 72-77
Author(s):  
Akihiro Takita ◽  
Taku Iwashita ◽  
Yusaku Fujii
Keyword(s):  
Effective Mass ◽  
Dynamic Error ◽  
Force Transducer ◽  
Spring Constant ◽  
Experimental Result ◽  
Correction Coefficient ◽  
Dynamic Force ◽  
Additional Mass ◽  
Dynamic Correction ◽  
Effective Spring Constant

Dynamic-error caused by the mass attached to the sensing part of a force transducer is experimentally investigated using the Levitation Mass Method (LMM), in which the dynamic-force applied to the force transducer is measured based on the definition of force, i.e. the product of mass and acceleration. It is experimentally proved that the change in the dynamic correction coefficient (DCC) is proportional to the additional mass as expected by the theory. The effective mass and the effective spring constant of the transducer with the additional mass are estimated from the experimental result. It is experimentally proved that the DCC for the transducer with the additional mass can be calculated using the estimated properties, i.e. the effective mass and the effective spring constant, and the dynamic-error can be corrected with the calculated DCC.

scholarly journals A Correction Method of Mixed Pesticide Content Prediction in Apple by Using Raman Spectra

2019 ◽  
Vol 9 (8) ◽  
pp. 1699 ◽  
Author(s):  
Li ◽  
Peng ◽  
Qin ◽  
Chao
Keyword(s):  
Quantitative Analysis ◽  
Detection System ◽  
Correction Method ◽  
Correction Coefficient ◽  
Characteristic Peak ◽  
Peak Intensity ◽  
Spectral Detection ◽  
The Difference ◽  
Lagrangian Interpolation ◽  
Raman Spectral

In the study, a new correction method was applied to reduce error during Raman spectral detection on mixed pesticide residue in apples. Combined with self-built pesticide residues detection system by Raman spectroscopy and the application of surface enhancement technology, rapid real-time qualitative and quantitative analysis of deltamethrin and acetamiprid residues in apples could be applied effectively. In quantitative analysis, compared with the intensity value of characteristic peaks of single pesticide with same concentration, the intensity value of characteristic peaks of the two pesticides decreased after mixing the pesticides, which affected the results severely. By comparing the difference in the intensity of characteristic peaks of single and mixed pesticides, a correction method was proposed to eliminate the influence of pesticides mixture. Characteristic peak intensity values of gradient concentration pesticide from 100 mg·kg−1 to 10−3 mg·kg−1 and Lagrangian interpolation were applied in the correction method. And a smooth surface was applied to describe the correction coefficient of characteristic peak intensity. Through detecting the characteristic peak intensity values of the mixed pesticide, correction coefficient would be obtained. Then real values of the peak intensity of pesticides and the content of each component of the mixed pesticide would be acquired by the correction method. Correlation coefficient of model validation exceeded 0.88 generally and Root Mean Square Error also decreased obviously after correction, which proved the reliability of the method.

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