中国科学院机构知识库网格系统: 检索

Soil organic matter content prediction using Vis-NIRS based on different wavelength optimization algorithms and inversion models 期刊论文 OAI收割
JOURNAL OF SOILS AND SEDIMENTS, 2023, 卷号: N/A
作者: Zhou, Wei; Xiao, Jieyun; Li, Haoran; Chen, Qi; Wang, Ting

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收藏 | 浏览/下载：15/0 | 提交时间：2023/05/06

Soil organic matter Visible near-infrared spectroscopy Competitive adaptive reweighted sampling Random forest Three-rivers source region

Constraining the X-Ray-Infrared Spectral Index of Second-timescale Flares from SGR 1935+2154 with Palomar Gattini-IR 期刊论文 OAI收割
The Astrophysical Journal, 2020, 卷号: 901, 页码: L7
作者: HXMT

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收藏 | 浏览/下载：24/0 | 提交时间：2022/02/08

Radio transient sources Magnetars Soft gamma-ray repeaters 2008 992 1471 Astrophysics - High Energy Astrophysical Phenomena Astrophysics - Instrumentation and Methods for Astrophysics Abstract: The Galactic magnetar SGR 1935+2154 has been reported to produce the first example of a bright millisecond-duration radio burst (FRB 200428) similar to the cosmological population of fast radio bursts (FRBs). The detection of a coincident bright X-ray burst represents the first observed multiwavelength counterpart of an FRB. However, the search for similar emission at optical wavelengths has been hampered by the high inferred extinction on the line of sight. Here, we present results from the first search for second-timescale emission from the source at near-infrared (NIR) wavelengths using the Palomar Gattini-IR observing system in the J band, enabled by a novel detector readout mode that allows short exposure times of ?0.84 s with 99.9% observing efficiency. With a total observing time of ?12 hr (?47,728 images) during its 2020 outburst, we place median 3Ҡlimits on the second-timescale NIR fluence of ?18 Jy ms (13.1 AB mag). The corresponding extinction-corrected limit is ?125 Jy ms for an estimated extinction of A_J = 2.0 mag. Our observations were sensitive enough to easily detect an NIR counterpart of FRB 200428 if the NIR emission falls on the same power law as observed across its radio to X-ray spectrum. We report nondetection limits from epochs of four simultaneous X-ray bursts detected by the Insight-HXMT and NuSTAR telescopes during our observations. These limits provide the most stringent constraints to date on fluence of flares at 10¹⁴ Hz, and constrain the fluence ratio of the NIR emission to coincident X-ray bursts to R_NIR ? 0.025 (fluence index ?0.35).

High-intensity attosecond X-ray source generation by using low-intensity spatial inhomogeneous mid-infrared pulse combined with an ultraviolet pulse 期刊论文 OAI收割
INTERNATIONAL JOURNAL OF MODERN PHYSICS B, 2017, 卷号: 31, 期号: 1
作者: Feng, Liqiang; Liu, Hang

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收藏 | 浏览/下载：70/0 | 提交时间：2019/06/20

High-order Harmonic Generation Attosecond X-ray Source Low-intensity Spatially Inhomogeneous Mid-infrared Pulse Xuv Controlling Pulse

Mixing ratio and carbon isotopic composition investigation of atmospheric CO2 in Beijing, China SCI/SSCI论文 OAI收割
2016
作者: Pang J. P.; Wen, X. F.; Sun, X. M.

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收藏 | 浏览/下载：25/0 | 提交时间：2017/11/09

Isotope ratio infrared spectroscopy (IRIS) delta C-13 Keeling plot Atmospheric CO2 source water-vapor urban atmosphere stable-isotopes delta-c-13 dioxide spectrometer spectroscopy city precipitation pollutants

Nitrogen use efficiency of atractylodes lancea plantlets in vitro under different inorganic nitrogen levels 期刊论文 OAI收割
Advanced Materials Research, 2013, 卷号: 610-613, 页码: 457-461
作者: Yanyou Wu; Kuan Zhao; Ying Chen; Jing Pang; Hongcheng Xu

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收藏 | 浏览/下载：15/0 | 提交时间：2020/12/23

Atractylodes Lancea image Analysis near Infrared Spectroscopy Nitrogen source Nitrogen Use Efficiency plantlet In Vitro

Simulation and experiment of the static FTIR based on micro multi-step mirrors (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies, May 24, 2011 - May 26, 2011, Beijing, China
作者:

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

In recent years Fourier transform spectrometer (FTS) with small size and low mass is required in many applications with growing need for real-time and small platform spectral detection. In this paper a micro Fourier transform infrared spectrometer (FTIR) based on spatial modulation mode was designed. This spectrometer has the advantages of high stability and simplified configuration. It also promises optical path differences (OPD) with high precision as MOEMS technology is used in manufacturing the key components. The simulation and the experiments with regard to this FTIR configuration have been done. Firstly the diffraction effect of the micro multi-step mirrors (MMSMs) is studied. We discuss the influence to the reversed spectrum by different mirror widths and different diffraction distances. Secondly we simulate and analyze the influence of the source solid angle to the spectral resolution. Thirdly we set up the theoretical model of the collimation error which is mainly from the defocus of the optical system and analyze the result caused by the collimation error. Fourthly a new discrete Fourier transform arithmetic using least-squares cosines progression (LSCP) is proposed which can reconstruct the spectrum with nonuniform sampled signals. Finally the MMSMs are fabricated used the MOEMS technology and the structural parameters are tested. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Design and demonstration of micro multi-step mirrors and light source in micro FTIR (EI CONFERENCE) 会议论文 OAI收割
6th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2011, February 20, 2011 - February 23, 2011, Kaohsiung, Taiwan
Liang Z.; Fu J.; Feng C.; Liang J.

收藏 | 浏览/下载：43/0 | 提交时间：2013/03/25

To obtain high resolution high signal-to-noise ratio (SNR) high reliability and real time in wide spectral range we study the space modulation Micro Fourier Transform Spectrometer (FTS) based on multi-step mirrors covering the spectral range of 3-5m and 8-12 m in theory and experiment. The influences of spectrum reconstruction caused by the diffraction and extended light source in Fourier Transform Infrared Spectrometer (FTIR) are analyzed. A method to reduce the noises in spectrum reconstruction and the relationship between coherent intensity and solid angle of light source are discussed. An extended light source with suitable size is chosen considering the requirement of SNR and spectrum resolving power in the optical design. Furthermore the fabrication of micro multi-step mirrors which is the core part of FTS is investigated. Three methods for fabricating multi-step micro mirrors are demonstrated. 2011 IEEE.

Design of programmable near infrared cold light source (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronics and Optoelectronics, ICEOE 2011, July 29, 2011 - July 31, 2011, Dalian, China
作者: Fu Q.; Wang B.; Wang B.; Wang R.

收藏 | 浏览/下载：31/0 | 提交时间：2013/03/25

In the near infrared spectroscopy detector of Charge-coupled Device requires very high stability for light source. We design the cold light source in the measurement of near infrared spectroscopy. Cold light source consists of high-power op amp OPA549 high current constant current source and proportion integral differential (PID) control algorithm. As is shown in the experimental results the method is better the overshoot is very small the stability is excellent in the process of soft-start. While light intensity was able to meet the requirements of near-infrared instruments to measure. 2011 IEEE.

The registration of aerial infrared and visible images (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Educational and Information Technology, ICEIT 2010, September 17, 2010 - September 19, 2010, Chongqing, China
作者: Liu J.; Wang Y.; Wang Y.; Wang Y.; Wang Y.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

In order to solve the registration problem of different source image existed on aerial image fusion algorithms based on Particle Swarm Optimization (PSO) are applied as search strategy in this paper and Alignment Metric (AM) is used as judgment. This study has realized the different source image registration of infrared and visible light with high speed high accuracy and high reliability. Basically with little restriction of gray level properties a new alignment measure is applied which can efficiently measure the image registration extent and tolerate noise well. Even more the intelligent optimization algorithm - Particle Swarm Optimization (PSO) is combined to improve the registration precision and rate of infrared and visible light. Experimental results indicate that the study attains the registration accuracy of pixel level and every registration time is cut down over 40 percent compared to traditional method. The match algorithm based on AM solves the registration problem that greater differences between different source images are existed on gray and characteristic. At the same time the adoption of combining the intelligent optimization algorithms significantly improves the searching efficiency and convergence speed of the algorithms and the registration result has higher accuracy and stability which builds up solid foundation for different source image fusion. The method in this paper has a magnificent effect and is easy for application and very suitable for engineering use. 2010 IEEE.

Fast color-transfer-based image fusion method for merging infrared and visible images (EI CONFERENCE) 会议论文 OAI收割
Multisensor, Multisource Information Fusion: Architectures, Algorithms, and Applications 2010, April 7, 2010 - April 8, 2010, Orlando, FL, United states
作者: Xu S.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

We present a computationally efficient color image fusion algorithm for merging infrared and visible images. At the core of the proposed method is the color transfer technique based on the linear YCBCR space. The method directly uses the grayscale fused image and the difference signals of the input images to construct the source YCBCR components then uses the statistical color transfer technique to form a color fused image that takes the target image's color characteristics. Two different strategies which respectively employ the pixel averaging fusion scheme and the multiresolution fusion scheme as the grayscale image fusion solution are proposed to fulfill different user needs. The simple strategy using the pixel averaging fusion scheme answers to a need of easy implementation and speed of use. And the complex strategy using the multiresolution fusion scheme answers to the high quality need of the fused products. In addition we also describe some useful theories about color-transfer-based image fusion. Experimental results show that the proposed color image fusion algorithm can effectively produce a natural appearing "daytime-like" color fused image and even using the pixel averaging fusion scheme to implement the grayscale fusion can also provide a pleasing result. 2010 Copyright SPIE - The International Society for Optical Engineering.