中国科学院机构知识库网格系统: 检索

Effect of biochar on permeability of compacted soil and its microscopic mechanism 期刊论文 OAI收割
CANADIAN GEOTECHNICAL JOURNAL, 2022
作者: Wan, Yong; Dong, Zhiwei; He, Xingxing; Liu, Ruiqi; Cai, Yangyang

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收藏 | 浏览/下载：18/0 | 提交时间：2023/08/02

biochar-amended soil physical properties permeability coefficient microporous structure influence mechanism

Spatiotemporal variation in groundwater level within the Manas River Basin, Northwest China: Relative impacts of natural and human factors 期刊论文 OAI收割
OPEN GEOSCIENCES, 2021, 卷号: 13, 期号: 1, 页码: 626-638
作者: Wu, Yage; Yang, Guang; Tian, Lijun; Gu, Xinchen; Li, Xiaolong

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收藏 | 浏览/下载：26/0 | 提交时间：2021/10/21

groundwater level influence factor contrast coefficient Manas River Basin

Composition and spatial difference of agro-industry carbon footprint in Hebei province, North China 期刊论文 OAI收割
ECOLOGICAL INDICATORS, 2019, 卷号: 97, 页码: 141-149
作者: Xie, Luyue; Xue, Qian; Yuan, Zaijian

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收藏 | 浏览/下载：40/0 | 提交时间：2020/01/10

Input-output table Agro-industry Carbon footprint Spatial difference Influence coefficient

Mining spatial information to investigate the evolution of karst rocky desertification and its human driving forces in Changshun, China 期刊论文 OAI收割
SCIENCE OF THE TOTAL ENVIRONMENT, 2013, 卷号: 458, 页码: 419-426
Xu, ErQi(许尔琪); Zhang, HQ; Li, MX

收藏 | 浏览/下载：26/0 | 提交时间：2013/08/20

Karst rocky desertification Human driving forces Fine scale Spatial technique Standard coefficient of influence

Mining spatial information to investigate the evolution of karst rocky desertification and its human driving forces in Changshun, China SCI/SSCI论文 OAI收割
2013
Xu E. Q.; Zhang H. Q.; Li M. X.

收藏 | 浏览/下载：33/0 | 提交时间：2014/12/24

Karst rocky desertification Human driving forces Fine scale Spatial technique Standard coefficient of influence guizhou province southwestern china county areas land environment region zone

Theoretical analysis of emission characteristics of second-order distributed feedback semiconductor lasers (EI CONFERENCE) 会议论文 OAI收割
Semiconductor Lasers and Applications IV, October 18, 2010 - October 19, 2010, Beijing, China
作者: Liu Y.; Liu Y.; Qin L.; Liu Y.; Wang L.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

Based on the modified coupled-wave theory the emission characteristics including threshold gain photon density distribution in the cavity and external differential quantum efficiency for second-order DFB lasers are investigated. Numerical simulation results show that for given device structure with wavelength of 1.55 m the feedback coupling coefficient and the surface radiation coupling coefficient of the second-order grating have great influence on the emission characteristics of the device. By choosing different duty cycles of the grating we can change the two coupling coefficients which affect the emission characteristics. For an overall consideration an optimal duty cycle of 0.43 is chosen. The optimized results show that the device works without degeneracy modes and spatial burning hole. Besides the side-mode suppress ratio (SMSR) and external differential quantum efficiency reach as high as 42 dB and 47% respectively. 2010 SPIE.

Chirp estimation of PZT for integrating-bucket method (EI CONFERENCE) 会议论文 OAI收割
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, April 26, 2010 - April 29, 2010, Dalian, China
作者: Zhang J.; Liu W.; Zhang J.; Zhang J.

收藏 | 浏览/下载：21/0 | 提交时间：2013/03/25

The nonlinear response of the PZT for the integrating bucket method is studied by our proposed method: discrete chirp Fourier transform (DCFT) and maximum likelihood estimation (MLE) techniques for the integrating bucket method. Based on the signal processing theory the intensity obtained from CCD is processed by the DCFT and thus nonlinear response and chirp coefficient of the PZT can be coarsely estimated. This is followed by the MLE method in which an iterative optimization process is complemented for accurately estimating the nonlinear response and chirp coefficient of the PZT. One key advantage of the proposed method is that not only the nonlinear response and chirp coefficient of the PZT can be acquired but also initial phase acquired. Our method is tested by simulating conditions under which a certain magnitude of nonlinearity is assumed. Nonlinear response attained by the DCFT is compared to that attained by the MLE and a difference between the actual nonlinear response of the PZT and our accurate estimation by the proposed method is revealed. Several factors that will have influence on the nonlinear response of the PZT are discussed. 2010 Copyright SPIE - The International Society for Optical Engineering.

Experiments of second harmonic generation output in pulsed TEA CO 2 laser (EI CONFERENCE) 会议论文 OAI收割
High-Power Lasers and Applications V, October 18, 2010 - October 19, 2010, Beijing, China
作者: Li D.

收藏 | 浏览/下载：52/0 | 提交时间：2013/03/25

It is always the hot subject to realize the output of high-power laser in the range of 3-5m wavelength. This rang of wave band has greatly important applications in military because it located in the atmosphere window. Generally there are two ways to obtain this range of laser wavelength. One way is through optical parameter oscillation (OPO) from shorter laser wavelength and the other is through second harmonic generation (SHG) from longer laser wavelength. Firstly the comparison between tow nonlinear crystals ZnGeP2 and AgGaSe2 is conducted for their nonlinear coefficient and damaging threshold in theory. The theoretical results show that the crystal AgGaSe 2 is more suitable for the SHG of pulsed TEA CO2 laser. When using pulsed TEA CO2 laser with wavelength of 9.3m to pumping AgGaSe2 SHG crystal the wavelength of 4.65m is obtained. In the condition of repetition rate 100Hz the upmost output power of single pulse is up to level of 1W which corresponding efficiency of SHG is about 6%. The experimental results show that the polarization of laser beam has greatly influence on the SHG output of the crystal. Under the radiation of 3MW/cm 2 from fundamental wave and the right position for maximal SHG output in the crystal when polarization of laser beam rotates 4.5 the SHG output of energy decrease about 30%. The research of this paper will make a foundation for further development of mid-infrared laser. 2010 Copyright SPIE - The International Society for Optical Engineering.

A sensitive solid-phase time-resolved fluorescence immunoassay apparatus (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging, June 17, 2009 - June 19, 2009, Beijing, China
作者: Song K.-F.; Li J.-L.; Zhang W.-L.; Wang Y.-L.

收藏 | 浏览/下载：37/0 | 提交时间：2013/03/25

In the device a He-Ne laser of flash frequency 1-20 Hz was adopted as exciting light source and three key technical problems have been solved successfully in order to enhance the detecting sensitivity and measuring stability of the device for time-resolved fluorimmunoassays(TRFIA) [1]. The first one is to design optimum exciting optical system so that the exciting light beam excite the sample most effectively. The second one is to have a project spectrum filter which can reduce the affection of the background light to the photomultiplier tube and also ensure influence of the stray light and mixed diffusion light to the sample fluorescence to the least the sample fluorescence through the integrating sphere and come to the grating monochromator The right wavelength will be chosed through changing the angle of incidence of the grating monochromator. The third one is to simulate the principle of sample averaging of BOXCAR averager. In the device SCM was used as primary controller and CPLD was used as timing controller. Through the preparation process signal-to-noise ratio(SNR) will be improved also adjust delay time ampling frequency and sampling number arbitrarily. By testing the sensitivity is 10-12mol/L(substance marked by Eu3+) examination repeat is &le2.5% examination linearity is from 10 -8mol/L to 10-12mol/L correlation coefficient is 99.98%(p&le0.01). The instrument is advanced for ultrasensitive detection of antigen and antibody and solve the tumor genetic variation the virus protein detection. 2009 SPIE.

Spatial variability of surface soil moisture content in a re-vegetated desert area in Shapotou, Northern China 期刊论文 iSwitch采集
JOURNAL OF ARID ENVIRONMENTS, 2008, 卷号: 72, 期号: 9, 页码: 1675-1683
作者: Pan, Y. -X.; Wang, X. -P.; Jia, R. -L.; Chen, Y. -W.; He, M. -Z.

收藏 | 浏览/下载：30/0 | 提交时间：2019/10/08

coefficient of variation grid-scale influence factors soil texture topography vegetation