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110 results on '"He, Guoxing"'

3. Gauss sums of some matrix groups over $\Bbb Z/n\Bbb Z$

Author

Hu, Su, He, Guoxing, Meng, Yingtong, and Li, Yan

Subjects
Mathematics - Number Theory
Abstract

In this paper, we will explicitly calculate Gauss sums for the general linear groups and the special linear groups over $\Bbb Z_n$, where $\Bbb Z_n=\Bbb Z/n \Bbb Z$ and $n>0$ is an integer. For $r$ being a positive integer, the formulae of Gauss sums for ${\rm GL}_r(\Bbb Z_n)$ can be expressed in terms of classical Gauss sums over $\Bbb Z_n$, while the formulae of Gauss sums for ${\rm SL}_r(\Bbb Z_n)$ can be expressed in terms of hyper-Kloosterman sums over $\Bbb Z_n$. As an application, we count the number of $r\times r$ invertible matrices over $\Bbb Z_n$ with given trace by using the the formulae of Gauss sums for ${\rm GL}_r(\Bbb Z_n)$ and the orthogonality of Ramanujan sums., Comment: 14 pages

Published
2018

8. Response of potential grassland vegetation to historical and future climate change in Inner Mongolia

Author

Liu Xiao-ni, Wang Hong-xia, Zhang De-gang, He Guoxing, Sun Bin, Ji Tong, Ren Zhengcao, Pan Dong-Rong, Li Qiang, and Han Tianhu

Subjects
geography, geography.geographical_feature_category, Ecology, Alpine-steppe, Steppe, Vegetation, Arid, Grassland, Tundra, Temperate climate, Environmental science, Physical geography, Precipitation, Ecology, Evolution, Behavior and Systematics
Abstract

Assessing current and potential future grassland vegetation types and distribution has important practical implications in grassland management. In this study, historical and projected climate data from Inner Mongolia were used to classify grassland classes for two historical (1960–1986 and 1986–2011) and two future periods (2021–2024 and 2041–2060) using the Comprehensive and Sequential Classification System (CSCS). Changes of grassland classes in these time periods were investigated. The results indicated that (1) using the CSCS provided an efficient approach to investigate the impact of historical and future climate on grassland classes and their distribution in Inner Mongolia over time and space; (2) since 1986, the precipitation in Inner Mongolia has declined, decreasing the semi-humid zone area and expanding that of arid and semi-arid areas. The area of Tundra and alpine steppe, Temperate zonal humid grassland and Temperate zonal forest steppe decreased, and that of Frigid desert, Semi-desert, and Steppe group increased; and (3) under the projected increase in temperature and decrease in precipitation in large areas in Inner Mongolia by 2060, the area of arid grassland classes will likely expand (Frigid desert, Semi-desert, and Steppe), and the grassland classes of Tundra and alpine steppe may gradually disappear. Government investment in infrastructure and grassland management measures such as introducing drought tolerant grass species and improved precipitation utilisation through irrigation are needed to adapt to the changing climate. Inner Mongolia should take advantage of the benefits of the increase in temperature in the eastern semi-humid region that would permit reduced grazing pressure in the western arid region.

Published
2021

14. Color temperature tunable white-light light-emitting diode clusters with high color rendering index

Author

He, Guoxing and Zheng, Lihong

Subjects
Color -- Research, Light-emitting diodes -- Optical properties, Light -- Optical properties, Astronomy, Physics
Abstract

A model for LED spectra at different drive currents is established. The simulation program of color rendering of a white-light LED cluster is developed according to the principle of additive color mixtures. The program can predict not only the spectral power distribution, chromaticity coordinates, correlated color temperature (CCT), and color rendering index (CRI), but also the drive currents of LEDs, luminous flux, input power, and luminous efficacy of white-light LED clusters. Three types of CCT tunable white-light LED clusters [warm-white/red/green/blue (WW/R/G/B), neutral-white (NW)/R/G/B, and cool-white/ R/amber/G clusters] with high CRI are found by simulation analysis and realized in our laboratory. The experimental results show that the WW/R/G/B cluster can realize CCT tunable white light with high CRIs (above 90) but lower luminous efficacies (below 65 lm/W), and that the NW/R/G/B cluster can realize CCT tunable white light with high CRIs (above 86), as well as high luminous efficacies (above 641m/W). [c] 2010 Optical Society of America OCIS codes: 230.3670, 330.1715.

Published
2010

16. Optimization of the light‐emitting diode daylight simulator based on the CIE metamerism index method.

Author

Zhao, Yifei, Zhong, Ping, and He, Guoxing

Subjects
LIGHT emitting diodes, DAYLIGHT, PHOSPHORS, QUANTUM dots
Abstract

By using spectral loss simulation, it was found that six spectral bands are needed to produce a daylight simulator with good performance. The optimization model for both Commission Internationale de l'Eclairage metamerism index and luminous efficacy (LE) of light‐emitting diode (LED) daylight simulator (LDS) was developed. The optimal LDSs with AA grade for D50, D55, D65, and D75 illuminants should consist of the violet LEDs with violet phosphor excited by an ultraviolet chip, and the white LEDs with green, yellow, and red phosphors excited by a blue chip. Their limit luminous efficacies under the ideal case could reach 179 to 204 lm/W. And finally, a scheme for a spectrally tunable LDS with AA grade was presented. [ABSTRACT FROM AUTHOR]

Published
2022
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19. Species composition and community structure of the Yulongxueshan (Jade Dragon Snow Mountains) forest dynamics plot in the cold temperate spruce-fir forest, Southwest China

Author

He Guoxing, Xu Kun, HE Rong-Hua, Li Dezhu, Chen Zhi-Fa, Liu De-Tuan, and Huang Hua

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Ecology, Forest dynamics, Biodiversity, Tropics, Species diversity, Forestry, Vegetation, Snow, 010603 evolutionary biology, 01 natural sciences, Geography, Habitat, Temperate climate, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Nature and Landscape Conservation
Published
2017

25. Optimization of a spectrally tunable daylight simulator using four quantum dot light‐emitting diodes for visual appraisal of color.

Author

Feng, Qi, Zhao, Yifei, Ding, Ke, Zhong, Ping, and He, Guoxing

Subjects
QUANTUM dots, DAYLIGHT, QUANTUM wells, QUANTUM efficiency, DIODES, LIGHT emitting diodes, TUNABLE lasers
Abstract

An optimization model for luminous efficacy of a spectrally tunable light‐emitting diode (LED) daylight simulator under constraint of metamerism index was developed. It was first reported that the optimal spectrally tunable LED daylight simulator of AA grade for D50, D55, D65, and D75 standard illuminants could consist of two quantum dot‐integrated LEDs (QDLEDs) with the ultraviolet chip and two other QDLEDs with the blue chip. The optimized spectral parameters of each QDLED, as well as photometric and colorimetric performances of D50, D55, D65, and D75 daylight simulators, were obtained by maximizing luminous efficacy under the metamerism index for both a visible and ultraviolet range less than 0.25. The limit luminous efficacies of four daylight simulators using four QDLEDs under the ideal case will reach 181 lm/W to 205 lm/luminous efficacies with a radiant efficiency of both the ultraviolet and blue chips of 60%, as well as a quantum efficiency of a quantum dots layer of 90%, will reach 100 lm/W to 112 lm/W. [ABSTRACT FROM AUTHOR]

Published
2020
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