KEYWORDS: Emissivity, Neural networks, Evolutionary algorithms, Data processing, Data modeling, Temperature metrology, Education and training, Optical engineering, Rockets, Pyrometry
A generalized inverse matrix-recurrent neural network (GIM-RNN) data processing algorithm for unknown emissivity was proposed to measure high-temperature by multiwavelength pyrometer (MWP). First, emissivity classification was realized quickly according to a solution from generalized inverse algorithm to underdetermined multiwavelength equation group. According to the relationship between the emissivity of 2 adjacent channels of the 6 channel thermometer used in this paper, 243 emissivity models (1 * 3 * 3 * 3 * 3 * 3) were designed for classification. Twelve of them were shown on the schematic diagram in the text. To make the figure clear and easy to observe, the prediction results of six common emissivity models were listed as the experimental results. Then, it was input into the corresponding RNN subnetwork to inverse temperature precisely. Simulation results showed that in the range of 1500 to 3000 K temperature, the relative error of the test set was within 1.0% for the network trained after classification by GIM, whereas the relative error of the test set was within 1.2% for the network trained without GIM classification. After 5.0% random noise was added to the inputting data, the relative error still was controlled within 1.5%, which reflected the good antinoise performance of the algorithm. Multispectral measurement data of rocket engine plumes is processed by the proposed algorithm in this manuscript. The inversion results are consistent with the theoretical results. It is indicated that the proposed algorithm has good adaptability to different materials. It is expected to become a general data processing algorithm for MWP.
This paper presents the detection and quantification of hogwash oil in soybean oils by means of absorption spectroscopy. Three types of soybean oils were adulterated with different concentrations of hogwash oil. The spectra were measured in the visible band using a white LED and a low-cost spectrometer. The measured spectra were processed by means of multivariate analysis to distinguish the adulteration and, for each soybean oil, to quantify the adulterant concentration. Then the visible spectra were sliced into two bands for modeling a simple setup made of two LEDs only. The successful results indicate potentials for implementing a smartphone-compatible device for self-assessment of soybean oil quality.
A numerical simulation pattern based on finite element algorithm is proposed for calculation of selective laser sintering
transient temperature field. The patter is based on the transient thermal radiation and the boundary conditions is
concerned soundly, particularly during the transient sintering the relation between thermal conductivity and transient
sintering temperature is set up on the basis of practical test to simulate practical sinter process. As a typical and
comprehensive sample, polystyrene SLS transient temperature field is analyzed. In the process of sintering the cube of
72mm×7mm×5mm, in case different parameters (laser power, scanning speed), both in a time the scanning line
temperature and in a point the temperature variation with time could realize. At a time, the simulation result accords with
the practical measurement result using the infrared thermometer. The results show the simulation transient sintering
temperature is 252°C and that of practical measurement is 241°C with laser scanning speed 2000mm/s and laser output
power 15W. the simulation transient sintering temperature is 313°C and that of practical measurement is 299°C with
laser scanning speed 1750mm/s and laser output power 40W. With the simulation system of SLS transient temperature
field developed in this paper, the SLS transient temperature field could be obtained rapidly and precisely to different
materials and parameters, the basis of selecting sintering parameters soundly and next analyzing of stresses and defects
were found firmly.
The backscattering coefficient and intensities of soot particles were calculated using Mie scattering theory for the
different incidences laser wavelengths and particle radii with complex refractive index also talked into consideration.
The calculation results indicated that at a scatter angle of 180°,the backscattering intensities can go up by 30% of
forward scattering intensities at different radii of particles if the resource laser wavelength is properly selected. This
conclusion provides a theoretical basis for the selection of laser sources and detector aiming at enhancing Signal Noise
Ratio.
An Orthogonal area array CCD spectrum tomography experimental system has been proposed to realize real-time
temperature diagnosis of Ar plasma jet. According to two-orthogonal-view reconstruction algorithm, two orthogonal
intensity signals can realize the emission coefficient field construction, then using spectrum relativity intensity method,
temperature field can be reconstructed. In this paper, two filters with different wavelength have been placed in front of
two-view orthogonal CCD, and plasma jet image has been obtained, of which point light intensity has been gotten using
digital image process technology according to the image of Ar plasma jet from CCD. Then using two-orthogonal-view
reconstruction algorithm and spectrum relativity intensity method reconstructed the Ar plasma jet temperature field.
The result shows that it agreed with the results from fiber scanning diagnosis system. The proposed experimental device
contented the real-time diagnosis request of plasma jet. It provided stabile base for real-time diagnosis of plasma jet
density field, pressure field and velocity field.
The "infrared laser atmospheric communication between warships" mainly solves the problems of secrecy and real-time communication in modern warfare condition. Concerning infrared laser atmospheric communication, the primary problem we should solve is how to acquire, point, and trace an object (shorted for APT) using the optical systems on warships. Therefore, a suitable platform is necessary. The platform is proposed in this paper, which includes the platform's general design framework and principle, the acquisition and tracing algorithm of optical signals, and technical targets. The algorithm is simple and practical. The design of the platform is practically significant for more research in infrared laser atmospheric communication system.
In the course of selective laser sintering (SLS), transient temperature has directly effect on protyping mechanism and quality. According to the analysis of transient temperature, infrared thermograph test method is proposed in this paper. Point and line temperature is measured immediately, and the test result is compared with numerical simulation. The result indicates that the test agrees with theory, and the proposed method provides steady base for selecting sintering parameter reasonable.
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