中国科学院机构知识库网格系统: 检索

Nonlinear Responses of Droughts Over China to Volcanic Eruptions at Different Drought Phases 期刊论文 OAI收割
GEOPHYSICAL RESEARCH LETTERS, 2022, 卷号: 49, 期号: 4, 页码: 11
作者: Chen, Kefan; Ning, Liang; Liu, Zhengyu; Liu, Jian; Yan, Mi

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volcanic eruption persistent drought different drought phases nonlinear effects climate modeling

Loading Effect of Chitosan Derivative Nanoparticles on Different Antigens and Their Immunomodulatory Activity on Dendritic Cells 期刊论文 OAI收割
MARINE DRUGS, 2021, 卷号: 19, 期号: 10, 页码: 15
作者: Xu, Chaojie; Xing, Ronge; Liu, Song; Qin, Yukun; Li, Kecheng

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chitosan derivative nanoparticles different antigens antigen selectivity encapsulation efficiency immune effects

烟台牟平海洋牧场季节性低氧对大型底栖动物群落的生态效应 期刊论文 OAI收割
生物多样性, 2019, 卷号: 27, 期号: 2, 页码: 200-210
作者: 李宝泉

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收藏 | 浏览/下载：21/0 | 提交时间：2020/06/17

低氧群落结构群落恢复敏感种机会种 hypoxia community structure community recovery sensitive species opportunistic species Hypoxia is a common phenomenon in the world's oceans, especially in the shallow waters of coastal zones. Rates of hypoxia are increasing due to global climatic changes and anthropogenic activities. Hypoxia can cause mass mortality of marine animals and can have severe negative impacts on marine ecosystems. To better understand the effects of hypoxia on macrobenthic communities, a survey was carried out in the Muping Marine Ranch (Yantai) during June, August and September of 2016. Results showed that seasonal hypoxia led to changes in benthic community structure, especially in terms of species composition and dominant species. The dominant species were Polychaeta Lumbrinereis latreilli, Sternaspis scutata and Mollusca Endopleura lubrica in summer. The opportunistic species Lumbrinereis latreilli increased, whereas, sensitive species such as Leptomya minuta, Glycera chirori, Upogebia major, Pontocrates altamarimus, Eriopisella sechellensis decreased during the hypoxic period of August. Hypoxia also reduced biodiversity indices. The effect of hypoxia on abundance and biomass were not significant, mainly because of the increase in the opportunistic Lumbrinereis latreilli, which counteracted the decline in abundance and biomass of other species. Individual physiological tolerance to hypoxia was different among species. Lumbrinereis latreilli showed higher tolerance to hypoxia in dissolved oxygen (DO) = 1.0 mg/L compared to other species. Some sensitive species, such as Leptomya minuta, Upogebia major, Pontocrates altamarimus and Eriopisella sechellensis showed lower tolerance when DO < 2.5 mg/L. When DO increased to 2.5 mg/L, the macrobenthic community start to recover gradually. The recovery extent and time needed were closely related to the degree of seasonal hypoxia.

The research of digltal CR medicine image adapitive enhancement method (EI CONFERENCE) 会议论文 OAI收割
4th International Conference on Mechanical and Electrical Technology, ICMET 2012, July 24, 2012 - July 26, 2012, Kuala Lumpur, Malaysia
Ming-Hui Z.; Yao-Yu Z.

收藏 | 浏览/下载：66/0 | 提交时间：2013/03/25

Digital CR medicine radiation image is in doctor's favor and has became medicine imaging technology new hot spot because of its high gray contrast powerful computer disposal function little radiation dosage non-film diagnosis different area consultation. But degradation of digital X-ray medical image such as low contrast and blurring during radiographic imaging caused by complexity of body tissue and effects of X-ray scattering and electrical noise etc. can worsen the results of analysis and diagnosis. So it is usually needed that CR medicine image is enhanced to improve its vision quality and easy to doctor's more accurate diagnosis. The general enhancement algorithms over enhancing the contrast and lose image details aiming at the defects an enhancement algorithm for CR image is proposed based on the ratio of deviation to mean of domain. The arithmetic enhance CR image edge details by adjusting factor K based on the ratio of deviation to mean of domain of CR image. Experiment results demonstrate that the algorithm enhances CR image detail and CR image enhanced has good visual effect the adaptive enhancement method is fit for CR medicine image. (2012) Trans Tech Publications Switzerland.

Research on infrared dim-point target detection and tracking under sea-sky-line complex background (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China
作者: Dong Y.-X.; Zhang H.-B.

收藏 | 浏览/下载：111/0 | 提交时间：2013/03/25

Target detection and tracking technology in infrared image is an important part of modern military defense system. Infrared dim-point targets detection and recognition under complex background is a difficulty and important strategic value and challenging research topic. The main objects that carrier-borne infrared vigilance system detected are sea-skimming aircrafts and missiles. Due to the characteristics of wide field of view of vigilance system the target is usually under the sea clutter. Detection and recognition of the target will be taken great difficulties.There are some traditional point target detection algorithms such as adaptive background prediction detecting method. When background has dispersion-decreasing structure the traditional target detection algorithms would be more useful. But when the background has large gray gradient such as sea-sky-line sea waves etc.The bigger false-alarm rate will be taken in these local area.It could not obtain satisfactory results. Because dim-point target itself does not have obvious geometry or texture feature in our opinion from the perspective of mathematics the detection of dim-point targets in image is about singular function analysis.And from the perspective image processing analysis the judgment of isolated singularity in the image is key problem. The foregoing points for dim-point targets detection its essence is a separation of target and background of different singularity characteristics.The image from infrared sensor usually accompanied by different kinds of noise. These external noises could be caused by the complicated background or from the sensor itself. The noise might affect target detection and tracking. Therefore the purpose of the image preprocessing is to reduce the effects from noise also to raise the SNR of image and to increase the contrast of target and background. According to the low sea-skimming infrared flying small target characteristics the median filter is used to eliminate noise improve signal-to-noise ratio then the multi-point multi-storey vertical Sobel algorithm will be used to detect the sea-sky-line so that we can segment sea and sky in the image. Finally using centroid tracking method to capture and trace target. This method has been successfully used to trace target under the sea-sky complex background. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Study on the calculation and application for asphericity of rectangle off-axis aspherics (EI CONFERENCE) 会议论文 OAI收割
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, November 19, 2008 - November 21, 2008, Chengdu, China
作者: Xuan B.; Song S.-M.; Xie J.-J.; Xie J.-J.; Zhang H.

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Asphericity which affects the manufacturing process and the grinding quantity is an important parameter of optical aspherics. In this paper the approximation the least square fitting wavefront aberration sag methods are given for the calculation of optical asphericity. The effects of different definitions of optical asphericity are analysed to optimize the process of manufacture. A sag method is presented to solve the best-fit sphere and asphericity for an off-aixs aspheric mirror with a rectangle aperture of 180mm145mm and polishing quantity and distribution plots are given. The optical manufacturing and testing technology for different choices of best-fit spheres and asphericity are described and analyzed. Therefore proper definition of optical asphericity which is useful to manufacturing is very important for optical fabrication and test. 2009 SPIE.

Double-swing method used for polishing off-axis aspherical mirrors (EI CONFERENCE) 会议论文 OAI收割
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, November 19, 2008 - November 21, 2008, Chengdu, China
作者: Chen Y.; Song S.-M.; Xuan B.; Wang P.; Li J.-F.

收藏 | 浏览/下载：45/0 | 提交时间：2013/03/25

Based on the characteristics of off-axis aspherical surface the comparison of simulation effects under different parameters is made. In order to achieve optimal parameters a new method used for polishing off-axis aspherical mirrors-Double-Swing Method (DSM) is proposed in this paper a high order off-axis rectangle aspherical mirror has been polished by DSM. The final result of profile measurements of 12nm and the polishing mechanism of DSM is introduced. The mathematical model of the DSM with steady movement state is established.The movement of this mathematical model is simulated in a programming language RMS is achieved. The result indicates that the method is of practice and has even higher working efficiency and precision. 2009 SPIE.

不同玻璃组分对掺铒碲酸盐玻璃光谱性质的影响 期刊论文 OAI收割
光子学报, 2008, 卷号: 37, 期号: s1
于春雷; 温磊; 汪国年; 张军杰; 胡丽丽

收藏 | 浏览/下载：1307/380 | 提交时间：2009/09/24

Alkaline earths Different effects Er³⁺ Fluorescence properties Fluorescence spectrum Glass compositions Glass modifiers Infrared wavelengths Ligand fields Luminescence lifetimes Melting methods Metal oxides Polarization effects Spectroscopic properties Tellurite glass

The synthesis and field emission property of carbon nanotubes on carbon fibers substrate (EI CONFERENCE) 会议论文 OAI收割
Technical Digest of the 20th International Vacuum Nanoelectronics Conference, IVNC 07, July 8, 2008 - July 12, 2008, Chicago, IL, United states
Leyong Z.; Weibiao W.; Jingqiu L.; Yuxue X.; Da L.; Song C.; Haifeng Z.

收藏 | 浏览/下载：33/0 | 提交时间：2013/03/25

Using ferrocene as catalyst precursor C2H2 as carbon source carbon nanotubes (CNTs) with uniform density were synthesized on carbon fibers substrate by floating catalyst method. The morphology and microstructure were characterized by field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscopy (HRTEM). The observation showed that the length of CNTs is about 2 m the average space between adjacent CNTs is about 300 nm and the diameter of CNT is about 45 nm. The less dense "short and stubby" aligned CNTs films should have good electron field emission characteristics. The results of field emission showed that the emission current of CNTs/carbon fibers was 5 A at the field of 2.5 V/m and the emission current can be 280 A with a field of 7 V/m (the specimen area is 0.25 cm2 and the distance between cathode and anode is 200 m). The calculation based on the F-N plot indicated that the field enhancement factor of CNTs tip is 499122. Using the conductivity and chemical stability of carbon fibers and the uniform and sparse density distribution of CNTs on carbon fibers substrate the tip predominance of carbon nanotubes can be exerted and simultaneously the effect of screening effects between adjacent carbon nanotubes on the field emission performance can also be effectively decreased. The CNTs synthesized on carbon fibers substrate has many predominances for the fabrication of cold cathode devices. For example using the removability of carbon fibers the cathode of CNTs/carbon fibers can be arbitrarily moved enlaced or combined to form different patterns and the cathode of CNTs/carbon fibers can be also fabricated in large size. Therefore CNTs/carbon fibers may have potential application in field emission displays.

The spectral feature analysis of semiconductor thin disk laser (EI CONFERENCE) 会议论文 OAI收割
Optoelectronic Materials and Devices II, November 2, 2007 - November 5, 2007, Wuhan, China
作者: Li J.; Wang L.-J.; Wang L.-J.; Ning Y.-Q.; Li J.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of semiconductor disk laser and analyses the heat effect by the experimentally measured photoluminescence spectrum of the laser chip at different pump power and different temperature. We can see that: with increasing pump power the thermal effects of the gain material becomes seriously and causes the saturation of carrier lifetime so the electron-hole pair created in the absorbtion layer have no enough time to rate to one of the wells and the non-radiative recombination happens in the barrier. When the thermal effects becomes stronger the chip will not lasing. This phenomenon is from the smaller energy offset between barrier and quantum well. We optimize the original structure design and experimental technology. A non-absorbing AlGaAs layer who is transparent to the pumping and laser wavelength is added to confine the carriers in the quantum wells. At the same time a DBR with double reflecting band is induced to improve the absorbing efficiency of the pumping light. The single QW is replaced by the three narrow QWs This three QWs structure can add the quantum state of QW increase the recombination probability of carriers in the QWs and reduce the heat effect. The chemical etch equipment is also improved to control the surface unevenness to be within 50 nm.