Search

Copyright of Acta Edulis Fungi is the property of Acta Edulis Fungi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To analyze the influences of surfaces topography on the laser damage and performance of KH2PO4 (KDP) crystal, the frequency features of machined surface KDP crystal surfaces were extracted and reconstructed by power spectral density and continuous wavelet transform. Wave optics theory was used to analyze the influences of frequency features on the subsurface light temperature fields of KDP crystals irradiated by 1.064 µm laser wavelength with the power of 20 MW/µm² for Ins. The results show that temperature of KDP crystals becomes larger with wavelength of surface frequencies closer to incident laser wavelength(1.064 µm). If the wavelength is over 20 µm, temperature of KDP crystals is unchanged with the changing of frequency features. The obvious wavelengths on the machined surface of KDP crystals obtained by cutting experiments are as 14 µm, 50 µm and 140 µm respectively, and the subsurface temperature of KDP crystal affected by these frequency features rises are as 56K, 22K and 12K. Maximum temperature of KDP crystals Increases with the increasing of amplitude under the same wavelength. With the increasing of surface frequency wavelength, the positon of the maximum temperature extends to the interior of the KDP crystals. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the low measurement precision, small measurement range and low stability of traditional displacement sensors, this paper propose and implement a displacement sensor based on varied line-space grating, with the displacement characteristic test and the error problems in the measurement process are accomplished and analyzed, respectively. In the experiment, the varied line-space grating is placed on the electric displacement platform. The incident position of the light spot is controlled by adjusting the displacement of the platform. Besides, the correlation between the grating displacement and the wavelength of the reflection spectrum first-order diffraction center is established to realize the wavelength coding of the displacement. The platform movement range is 0~20 mm, with step length of 2 mm, and the round trip repeated measurement is made for 6 times. The central wavelength at each shift point is recorded and the displacement characteristics of the sensor are calibrated. Based on the error analysis of the central wavelength data generated by repeated measurements at each shift point, the standard deviation of multiple measurements at each point is analyzed by using Bessel formula combined with the Pieters method. The reliability of the data is further determined by combining with the 3σ criteria. The experimental results show that the sensor system has no systematic error and gross error. Also, the wavelength and displacement of the sensor change linearly, and the linearity of multiple repetitions is better than 0.994 6. The average displacement sensitivity of the sensor's full range is 16.67 nm/mm. The content of this paper can provide a certain research reference for displacement sensing system based on varied line-space grating.

Copyright of Study on Optical Communications / Guangtongxin Yanjiu is the property of Study on Optical Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Central China Normal University is the property of Huazhong Normal University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem that the traditional machine vision has low discrimination accuracy when realizing the fresh level recognition of spinach, A new method for fresh grade recognition of spinach based on hyperspectral and deep learning was conducted in this study. Round leaf spinach stored in room temperature 10oC on a daily basis was regarded as research objects. The spinach was divided into three grades of fresh, relatively fresh and corruption according to the score calculated by considering 6 factors: fresh spinach days of storage, appearance, water content, chlorophyll a, chlorophyll b, and carotenoids. After 6 ROI areas was obtained from the hyperspectral image of spinach leaves shot with high spectrum imaging instrument, the mean reflectance of ROI region was calculated. Based on the grouping elite strategy genetic algorithm, an adaptive grouping strategy was used to screen out a set of wavelengths A, A={389.55 nm, 401.629 nm, 742.325 nm, 949.939 nm, 1 025.662 nm}. Then the artificial grouping strategy was also used for wavelength screening. The number of statistical groups was the wavelength selected by n = 1, 2, 3...n, and the four frequencies with the highest frequency were placed in the set B, B={389.55 nm, 536.365 nm, 742.325 nm, 1 025.662 nm }. The six wavelengths in the A∪B set were combined as the final selected wavelengths, and these wavelengths were better able to identify the fresh grade of spinach. Define training set R and test set T, R and T each containing 240 spinach samples. Using the SVM classifier, based on the spine reflectance corresponding to the six wavelengths, a fresh grade classification test based on the spectral characteristics to define spinach was separately performed. After 10 trials, the mean value of recognition accuracy was obtained, and the three wavelengths with the highest recognition rate were found, which were 389.55, 742.325 and 1 025.662 nm, respectively. The corresponding recognition rates were 62.08%, 60.00% and 60.42%, respectively. This indicated that the recognition rate of spinach fresh grade was low based on spectral characteristics. In addition to the spectral properties, spinach's hyperspectral image also contains rich image information corresponding to all wavelengths, so further spine fresh grade recognition based on image features can be performed. The spinach images corresponding to the three wavelengths extracted from the hyperspectral image set constituted an image sample library. Based on the deep learning technology, the spine fresh grade recognition model was established. The recognition experiments were carried out on four types of images (NormImg389、NormImg742、NormImg1 025 和NormImg_merge) in the image sample library. The average recognition accuracy of the three experiments was 79.69%, 68.75%, 69.27% and 80.99%. The NormImg389 and NormImg_merge test sets had higher recognition rates, which were close to 80%. The image recognition rate of spinach in NormImg_merge was up to 80.99%, which indicated that when the spinach fresh level recognition was performed, the images corresponding to the three wavelengths were merged. Identifying can get the best classification results. This study achieved the non-destructive testing of the fresh grade of round leaf spinach, and the research results provided quality assurance for industrial processing and marketing, which has practical and theoretical significance. [ABSTRACT FROM AUTHOR]

Potential-induced degradation (PID) is one of the most important and prominent module degradation mechanisms leading to significant yield losses. It was shown that Na decorated stacking faults at the SiNX/Si interface region are responsible for the mechanism of increasing non-saturation hanging states density at the front surface. In order to investigate the characteristics of recombination of non-equilibrium minority carriers at the front surface, the paper analyzes the band gap structure and electrical field at surface of solar cells material after PID test, and then deduces the model of front surface recombination velocity by measuring internal quantum efficiency (IQE) of solar cells under short wavelength monochromatic light, which is derived by Poisson equation, and continuity equation and current density equation of semiconductor physics. For the certain sample, the parameters of the materials are known, such as absorbance coefficient, and hole diffusion coefficient, and p-n junction depth, and hole diffusion length, which is modified by electrical field at front surface. And then, the front surface recombination velocity of the samples after PID test is calculated by the IQE model, which is measured by QE (quantum efficiency) equipment. In this paper, the experiment is carried out at the p-type base region with (100) p type CZ monocrystalline silicon, whose impurity density is 1.5×1016 cm-3, minority carrier lifetime is 7.2 μs, and area is 100 mm × 100 mm. The samples are prepared using constant source for the POCl3 diffusion, which is followed by plating SiNX as passivation and anti-reflection film. The last procedure is printing aluminum slurry at the back surface of samples as black electric field, where impurity density is 1×1020 cm-3. At the same time, different diffusion conditions and front surface velocity are simulated by PC1D software, in order to study the influencing mechanism of impurity and velocity at front surface of samples after PID test. And then, the front surface recombination velocity of the samples is calculated and compared with the samples which are PID-free, which shows that the values of surface recombination velocity are more reliable when using wavelengths in range of 310-360 nm than other wavelengths. Additionally, I-V characteristics of the samples before and after PID test are simulated by PC1D. It is obvious that the output characteristics of the sample 1, which has good passivation and low front surface velocity, are degraded most seriously after PID test than others. It is assumed that Na ions drift through the SiNx layer under the influence of a strong electric field and increase the impurity density at front surface, which leads to I-V characteristics degradation. For the sample 2 and the sample 4, which have poor passivation and low impurity density at front surface, electron barrier at front surface region can reduce the impacts from Na ions. Correspondingly, the open circuit voltage of these samples has few effects, however short circuit current of the samples is decreased. The result of the sample 3 shows that PID has little influence on the output electric characteristics of solar cell with higher impurity density at front surface, whether the passivation condition is good or not. In general, the experiments indicate that surface recombination velocity of PID solar cells is higher than that of PID-free, and I-V characteristics of solar cells, which have good passivation conditions and low front surface recombination velocity, are deteriorated, however, PID has few effects on the solar cells with the poor passivation conditions and high front surface recombination velocity. [ABSTRACT FROM AUTHOR]

With the rapid development of economy and modern industrial and agriculture, more and more heavy metals such as cadmium, copper and zinc come into environment. Heavy metals are not only polluting soil, water and air, but also affecting crops growth and the yield, and affecting food security and human health by food chain. It was reported that heavy metal contamination of arable land in China has reached 20 million hm2, accounting for the country's total cultivated area of 1/6. Therefore, many researchers pay more attention to the heavy metal pollution problems increasingly. At present, researchers usually use chemical and biological methods to test the pollution extent of different heavy metals. Those methods are time consuming and even cause the second environmental pollution. Using spectral analysis to monitor the heavy metals stress on crops is an innovative approach. However, the effect of heavy metal pollution on crops spectrum is still in the exploration stage. Because of the effect of different factors such as plants and environment, the diagnosis of heavy metal stress mechanism on plant is still unclear. The crop tolerance at different growth stages are different from heavy metals, therefor, to explore the critical concentration of different heavy metals stress on crops at the different growth stages has certain practical significance. In order to monitor the crop stress of heavy metal pollution rapidly, under open field plot conditions and using canopy spectral analysis, the canopy spectral features of wheat at different stages of tillering, jointing and heading were studied at the different treatments of Cu (0, 100, 300, 600 and 900 mg/kg) and Zn (0, 250, 500, 750 and 1 000 mg/kg), according to the national soil quality standard (GB15618-1995) of China. The experiment was conducted in the experimental field of Qingdao Academy of Agricultural Sciences in Chengyang District of Qingdao City, in October 2014 to June 2015. The total area of the test plot was 180 m2, and the test soil type is Shajiang black soil, with the pH value of 6.85, the organic matter content of 22.6 g/kg, nitrogen content of 94.6 mg/kg, available phosphorus content of 77.5 mg/kg, the available potassium content of 113 mg/kg, copper content of 28.1 mg/kg and zinc content of 73 mg/kg. The experiment was conducted by traditional management. The results indicated that at different concentration treatments of copper (Cu) and zinc (Zn), the canopy spectral reflectance in the visible band (350-760 nm) increased obviously with the concentration treatments increasing of Cu and Zn at the tillering and jointing stages of wheat, however, the canopy spectral reflectance of near infrared band (760-900nm) reduced with the increasing concentration of Cu and Zn treatment levels. Wheat canopy spectral reflectance appeared red edge position and red valley position shifting toward short wavelength called “blue shift” at tillering stage of wheat under the different concentration treatments of Cu and Zn. At the tillering stage of wheat, copper treatments of 600 and 900 mg/kg and at the jointing stage copper treatment of 900 mg/kg, the red edge normalized index value (NDVI705) were less than 0.2. At the tillering stage, zinc treatments of 750 and 1 000 mg/kg, the red edge normalized index value (NDVI705) was less than 0.2. This research also indicated that the wheat canopy spectral features response obviously to the threshold values concentration treatment level of Cu were between 300 and 600 mg/kg, and Zn were between 500 g and 750 mg/kg. [ABSTRACT FROM AUTHOR]

During the past decades, soil hyperspectral reflectance had been showed to be a rapid, convenient, lowcost and alternative method for estimating soil key properties. However, the hyperspectral dataset may have thousands of variables because modern spectroscopy instruments usually had a high resolution. Moreover, the fullspectrum includes many wavelengths which could contribute the collinearity, redundancy and noise to models. Thus, the key variable selection is an important step in soil hyperspectral modeling analysis. The main objectives of this study were to compare the prediction accuracy of different models developed by using several variable selection algorithms for the estimation of soil organic matter (SOM), and the performance of fullspectrum partial least squares regression (PLSR) was also used to compare with. Fifty six soil samples at 0-20 cm depth were collected from Gong’an Countyin Jianghan Plain. The spectral reflectance of soil samples was measured by an ASD FieldSpec3 instrument under the laboratory conditions. Meanwhile, physical and chemical properties of these soil samples were analyzed. KennardStone algorithm was used to divide soil samples into calibration sets with 40 samples and prediction sets with 16 samples. Different spectral preprocessing methods were conducted for raw soil reflectance. Then three variable selection methods such as UVE (uninformative variables elimination), CARS (competitive adaptive reweighted sampling), SPA (successive projections algorithm) were used to select key variables. At last, based on variables selected by different methods, we used partial least squares regression method with full cross validation to build quantitative inversion models for SOM. The prediction accuracies of these optimal models were assessed by comparing determination coefficients (R2), root mean squared error (RMSE) and relative percent deviation (RPD) between the estimated and measured SOM. The results showed that, the prediction accuracies of different spectral preprocessing methods were significantly diverse, and SavitzkyGolay1st derivative smoothing with nine points (SG +1stD) was the best preprocessing method, from which the improvements of approximately 37.29% in RPD were achieved for SOM prediction.Among the three single variable selection methods, CARS method was superior to other two variable selection methods while retaining good model prediction accuracy with R2 value of 0.88 and RPD value of 2.84, and it could extract the key variables for SOM effectively.Comparing all variable selection methods comprehensively, the PLSR model built by using CARSSPA method on 37 characteristic wavelengths selected from fullspectrum of 2001 wavelengths achieved the optimal performance.Its values of determination coefficients R2 and relative percent deviation (RPD) between the estimated and measured SOM for the predicted model were 0.92 and 3.60, respectively. By using CARSSPA method, the total number of selected variables was only 1.85% of fullspectrum. And the CARS-SPA-PLSR model was feasible and reliable for estimating the SOM using the hyperspectral reflectance of soil samples under the laboratory conditions. Appropriate variable selection could enhance the performance of a model, simplify the regression models, and increase the accuracies of SOM estimation. In the future, the CARS-SPA-PLSR inversion model can be used as a reference for development of proximal soil sensing devices for this region and online monitoring of SOM. [ABSTRACT FROM AUTHOR]

Copyright of Cotton Textile Technology is the property of Cotton Textile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fiber Bragg grating(FBG) fire detector was packaged by use of a special alloy material.Related temperature sensing experiment showed that temperature sensitivity of the fire detector is(1.755 times) than bare grating,and temperature sensitization was achieved.A mine-used fire detection system with FBG was designed by use of the fire detector and FBG wavelength demodulation device,data transmission and control bus,data control center,etc.The system uses the FBG wavelength demodulation device to demodulate wavelength of light signal which is reflected by field detecting FBG and measure the changing rate of the wavelength,then,firing or not could be known through the changing rate of the wavelength.The experiment showed that the system has high accuracy of fire detection and can shorten warning time.

Orius sauteri is used as a biological control agent against agricultural pests such as thrips and whiteflies. We investigated the spectral wavelength preference of O. sauteri in a hexagonal arena equipped with six LED lights of different colors: UV (365 nm), violet (405 nm), blue (450 nm), green (525 nm), orange (590 nm), and red (660 nm). Adults were released in the center of the arena and their phototactic behavior toward the LED lights was observed. Approximately 50% of non-mated individuals moved toward the violet light, with no difference between sexes. The spectral preference of males did not change after mating, whereas the preference of females changed dramatically from violet to UV after three days' mating [ABSTRACT FROM AUTHOR]

Trapping tests for melon thrips, Thrips palmi, were carried out using 17 colored resin sheets, 8 LED lights, and 2 types of plate. Among the colored resin traps, more thrips were captured by resin with a peak spectral reflectance between 481 and 523 nm. Among the 8 LED light traps covered with a diffuser, more thrips were captured by LED traps with peak wavelengths of 500 or 525 nm. When the LED light traps were covered by a transparent acrylic plate, the 470-nm LED trap captured as many thrips as the 525-nm LED trap, and both produced the highest capture rate. In an experiment that combined LED traps with one of three wavelengths( 470, 500, or 525 nm) and either a diffuser or a transparent plate, the 470-nm LED trap captured fewer thrips than the other combinations, and the 470-nm trap covered by a diffuser captured significantly fewer thrips than the same trap covered by a transparent plate. Significantly higher captures were obtained using 500- or 525-nm LEDs covered by transparent plates. Thus, melon thrips were stably attracted to light at wavelengths from 500 to 525 nm. [ABSTRACT FROM AUTHOR]

We studied the effective action spectrum of phototactic behavior and compound eye spectral sensitivity in the yellow tea thrips, Scirtothrips dorsalis Hood. We compared positive phototactic responses in S. dorsalis among several light wavelengths( 355, 405, 468, 525, 590, 631, 660 nm). Scirtothrips dorsalis showed strong positive phototaxis at 355 and 525 nm. We determined the spectral sensitivity of the compound eye by recording electroretinographic (ERG) responses to monochromatic stimuli ranging from 300 to 740 nm. The spectral sensitivity showed peaks at 360 and 520 nm. These results suggest that the action spectrum of the phototactic behavior of S. dorsalis matches its eye's spectral sensitivity. [ABSTRACT FROM AUTHOR]