ABSTRACT
Lysimachiadanxiashanensis, a new Primulaceae species, endemic to the Danxia landscape in Guangdong Province, China, is described and illustrated. This new species is morphologically similar to L.pseudohenryi, L.phyllocephala, L.congestiflora and L.kwangtungensis, but it differs from the similar species by its purplish-red plants, petiole without wings, calyx with orange glandular and the corolla margin serrated on upper half with orange-red glandular punctates. This new species belongs to Lysimachiasubgen.Lysimachiasect.Nummularia. Phylogenetic analysis confirmed that L.danxiashanensis is a distinct clade, based on the combined data of ITS and rbcL sequences. The conservation status of the new species was evaluated as Endangered (EN) according to IUCN Red List Categories and Criteria.
ABSTRACT
The isothermal surface equation of tri-band radiation thermometry with linear emissivity model has been deduced, based on tri-band radiation measurement equations. The isothermal surface equation is the point multiplication of measurement signal vector and measurement signal coefficient vector. The solution algorithm for tri-band radiation thermometry defined as dichotomy with coefficients stored in this paper has been developed because of the characteristics of measurement signal vector which is only the function of temperature and the advantage of dichotomy in solving non-linear equation. And the solution algorithm has been achieved by C++ program. The curves of isothermal surface equations at specific measurement signal vectors have been investigated and the results show that the curves are monotone at a greater range of temperature and the tail of curves tend to be positive from minus with the increase of V3. The analyses of error and time complexity have been carried out and the results show that the maximum error is (Tmax-Tmin)/2num+1 when the number for the solution algorithm is Num, and there are about 3Num+1 multiplication and 2Num+1 addition in every dichotomy process without division and logarithm, which can crease the solving rate dramatically.
ABSTRACT
For the influence of temperature drift of the spectral responsivity on the repeatability infrared spectral emissivity measurement system, a temperature drift correction method is proposed based on the polynomial fitting. By analyzing the function of detector output voltage depended on its temperature. After studying the functional relationship between the temperature and spectral responsivity of detector, the spectral response curve varies with temperature is fitted and get the fitting equation. Calculating the drift correction factor of spectral responsivity, the output voltage of infrared detector is corrected. The effect of spectral response drift on the output voltage of detector is eliminated. With the development of temperature drift correction device of spectral responsivity, the temperature drift curve of spectral response is measured. Compared to the exponential fitting, the fitting consistency of sixth-order polynomial curve is excellent. Because of the application of this method, the repeatability of spectral emissivity measurement system is improved.
ABSTRACT
For the inevitable errors of the monochromator in the process of producing and installing, it must be calibrated before being used. For the traditional calibration method using mercury lamp, the number of wavelengths limits the calibration precision of the monochromator. Based on the principle of grating monochromator, calibration method for the monochromator based on continuous spectrum light source is proposed. Calibration system is designed and built, which is composed of broadband light source using tungsten halogen lamp, power source, light filter, the monochromator, spectroscopy to detect the intensity of the monochromator output, and computer. Divide the intensity detected on the output of monochromator by the intensity detected directly the tungsten halogen lamp. The result is the transmissivity function of the monochromator eliminating the influence of the halogen tungsten lamp radiation and the spectrometer response function. On a certain dial number, the transmissivity function is measured, normalized and the peak wavelength is calculated. 22 groups of wavelength data and dial number are acquired. 8, 14, 18, 22 points are chosen separately to calibrate the relationship between the wavelength and the dial number of monochromator by linear fitting and quadratic fitting. Experimental results show the calibration result in 22 points is better than others, (8 points similar to the calibration method using mercury lamp). The result of quadratic fitting with 22 points as the final result is better than linear fitting. So the calibration method for monochromator using the continuous spectrum light source with more calibration points is superior to the traditional calibration method using mercury lamp.
ABSTRACT
In order to measure the temperature of the object in the case of non-diffuse emission within a finite solid angle, a new concept for radiation thermometry, the apparent emissivity, has been presented firstly after a proper mathematical transformation of the radiation measurement equation and its characteristics have also been investigated. The results indicated that although the apparent emissivity is complex in form, it is only the function of the wavelength for one measurement even if the object is non-diffuse. So the temperature of the object in the case of non-diffuse emission within a finite solid angle can be solved by modeling the apparent emissivity. Then the equations for monochromatic and wavelength radiation measurement were deduced. At the same time, the measurement of temperature for a finite area was investigated, and it can be found that if the temperatures of the finite area are the same, they can also be determined by modeling the apparent emissivity.
ABSTRACT
In view of the influence of non-ideal reference standard on spectral emissivity measurement, by analyzing the principle of infrared emissivity measurement system based on integrating sphere reflectometer, a calibration method suitable for measuring spectral emissivity system using the reflection measurement was proposed. By fitting a spectral reflectance curve of the reference standard sample to the given reflectance data, the correction coefficient of measurement system was computed. Then the output voltage curve of reference standard sample was corrected by this coefficient. The system error caused by the imperfection of reference standard was eliminated. The correction method was applied to the spectral emissivity measurement system based on integrating sphere reflectometer. The results measured by the corrected system and the results measured by energy comparison measurement were compared to verify the feasibility and effectivity of this correction method in improving the accuracy of spectral emissivity measurement.
ABSTRACT
At present, Multispectral pyrometer used in high-temperature measurement has already had high resolution and high signal to noise ratio. However, the non-source temperature (higher than 3 000 degrees C) calibration falls far behind the development of multispectral pyrometer and has already seriously hindered the precision and application range of the pyrometer. In order to break through the limitation of calibration of non-source temperature, a new calibration method was put forward in the present paper. The temperature-voltage (T-U) model was formed based on power function where output voltage U of the multispectral pyrometer was derived from its corresponding known temperature point. Based on the model, derivative least square method was used to obtain the parameters of the model to realize the non-source temperature calibration. Both theoretical and experimental data proved the efficiency and precision of the calibration method. In addition, within the spectral range of high-temperature measurement pyrometer (0.4-1.1 microm), the range of non-source temperature calibration with precision better than 3 per thousand, 1% and 3% respectively have been divided theoretically.
ABSTRACT
To study thermal radiation properties of special materials at high temperature in aerospace fields, the ultrahigh temperature spectral emissivity measurement system with Fourier spectrometer has been established. The linearity of system is the guarantee of emissivity measurement precision. Through measuring spectral radiation signals of a blackbody source at different temperatures, the function relations between spectral signal values and blackbody spectral radiation luminance of every spectrum points were calculated with the method of multi-temperature and multi-spectrum linear fitting. The spectral radiation signals of blackbody were measured between 1 000 degrees C and 2 000 degrees C in the spectral region from 3 to 20 microm. The linear relations between spectral signal and theory line at wavelength of 4 microm were calculated and introduced. The spectral response is well good between 4 and 18 microm, the spectral linearity are less than 1% except CO2 strong absorption spectrum regions. The results show that when the errors of measured spectrum radiation and linear fitting theory lines are certain, the higher the temperature, the smaller the spectral errors on emissivity. The linearity analysis of spectrum response is good at eliminating errors caused by individual temperature' disturbance to the spectra.
ABSTRACT
Tunable diode laser absorption spectroscopy (TDLAS) was characterized by ultra-narrow line width laser and wavelength modulation, which makes it possible to scan a single absorption line. TDLAS has an advantage in trace gas analysis for its high resolution, high sensitivity and quick response. The 1 626.8 nm absorption line of ethylene was selected for detecting by analyzing its absorption line characteristic. The TDLAS system was developed with a white type multi-pass cell, combined with wavelength modulation and harmonic detection. Ethylene concentration ranges from 20 to 1 200 ppmv were tested using this system. The estimated detection limit of the system is 10 ppmv.
ABSTRACT
A kind of multi-target multi-spectral thermometer has been developed to be used in large explosive environment. At the moment of explosion, the thermometer simultaneously collects explosion flame radiation energy under different spectra after the lights go through the prism spectrometer. The second measurement method was used to calculate true temperature and emissivity of the explosion flame. The fiber-optic long-distance transmission technique and fiber coupling technique were used for the first time in optical system design, which largely solves the problems of anti-vibration, anti-explosion and anti-electromagnetic interference for the core of the instrument. The high-speed acquisition system and multi-stage amplification system were used to realize instaneous collection of the rapidly changing explosion flame temperature. The wireless long-distance transmission was used to ensure the staff safety.
ABSTRACT
For realizing real-time 3D temperature field reconstruction of Ar plasma jet, an orthogonal area array CCD (charge coupled device) spectrum tomography experimental system was proposed according to spectrum relative intensity diagnosis method. The size of tested field was measured using comparison between the tested field image caught through CCD and the plotting paper image when plotting paper was placed in the tested field position with no plasma jet; the emission intensity distribution of tested field was obtained using stepping motor taking fiber probe to scan tested field, and the spectrum analysis instrument was used to show the spectrum intensity information. Based on spectrum selection principle of the spectrum relative intensity method, spectra at 696.5 and 763.5 nm were studied as characteristic spectrum. Novel grad attenuation was designed based on the size and intensity distribution of tested field for not exceeding limen of CCD and avoiding the spectrum information loss at tested field edge. The narrowband filter was set between grad attenuation and CCD, so the whole tested spectrum information can be stored in computer real-time. According to orthogonal two-view spectrum tomography reconstruction algorithm, when tested field is axially symmetric, the reconstruction result is well. So four area array CCDs is placed orthogonally, and the same spectrum narrowband filters are placed in front of two orthogonal CCDs to reconstruct 3D emissivity factor field. Based on the 3D emissivity factor field and spectrum relative intensity theory, 3D temperature field of the tested field was reconstructed satisfactorily. The reconstruction result showed that it agreed with the results from fiber scanning diagnosis system, and the uncertain degreed is 3.3%. The proposed experimental device meets the needs of real-time 3D temperature field reconstruction. It provided a stable base for real-time diagnosis of plasma jet density field, pressure field and velocity field.
ABSTRACT
The plume temperature of a solid propellant rocket engine (SPRE) is a fundamental parameter in denoting combustion status. It is necessary to measure the temperature along both the axis and the radius of the engine. In order to measure the plume temperature distribution of a solid propellant rocket engine, the multi-spectral thermometry has been approved. Previously the pyrometer was developed in the Harbin Institute of Technology of China in 1999, which completed the measurement of SPRE plume temperature and its distribution with multi-spectral technique in aerospace model development for the first time. Following this experience, a new type of multi-target multi-spectral high-speed pyrometer used in the ground experiments of SPRE plume temperature measurement was developed. The main features of the instrument include the use of a dispersing prism and a photo-diode array to cover the entire spectral band of 0.4 to 1.1 microm. The optic fibers are used in order to collect and transmit the thermal radiation fluxes. The instrument can measure simultaneously the temperature and emissivity of eight spectra for six uniformly distributed points on the target surface, which are well defined by the hole on the field stop lens. A specially designed S/H (Sample/Hold) circuit, with 48 sample and hold units that were triggered with a signal, measures the multi-spectral and multi-target outputs. It can sample 48 signals with a less than 10ns time difference which is most important for the temperature calculation.
ABSTRACT
The problem of determining the particle size range in the visible-infrared region was studied using the independent model algorithm in the total scattering technique. By the analysis and comparison of the accuracy of the inversion results for different R-R distributions, the measurement range of particle size was determined. Meanwhile, the corrected extinction coefficient was used instead of the original extinction coefficient, which could determine the measurement range of particle size with higher accuracy. Simulation experiments illustrate that the particle size distribution can be retrieved very well in the range from 0. 05 to 18 microm at relative refractive index m=1.235 in the visible-infrared spectral region, and the measurement range of particle size will vary with the varied wavelength range and relative refractive index. It is feasible to use the constrained least squares inversion method in the independent model to overcome the influence of the measurement error, and the inverse results are all still satisfactory when 1% stochastic noise is added to the value of the light extinction.
Subject(s)
Infrared Rays , Light , Scattering, Radiation , Particle Size , Spectrophotometry , Spectrophotometry, InfraredABSTRACT
Considering some defects of back-propagation neural network (BP), a new algorithm combining genetic algorithm (GA) with BP was described. The application of GA-BP to the data processing of multi-spectral thermometry was proposed. The simulation experiments, based on GA-BP algorithm and BP neural network respectively, show that the recognition precision of trained emissivity samples is +/-5 K and +/-10 K respectively, and that of untrained emissivity samples is +/-10 K and +/-20 K respectively. No matter GA-BP algorithm or BP neural network is used, in general, the recognition precision of trained emissivity samples is higher than that of untrained emissivity samples. The recognition precision of true temperature is lower near the edge of sample sets. The GA-BP algorithm was more efficient than the BP neural network in the true temperature measurement.
