检索结果-南通市图书馆

Spatial Process of Green Infrastructure Changes Associated with Rapid Urbanization in Shenzhen,China

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2013年第1期23卷 113-128页

作者： CHANG Qing LI Shuangcheng WANG Yanglin WU Jiansheng xie Miaomiao Department of Ornamental Horticulture and Landscape Architecture China Agricultural University College of Urban and Environmental Sciences Peking University Key Laboratory for Environmental and Urban Sciences Shenzhen Graduate SchoolPeking University School of Land Science and Technology China University of Geosciences

Through a case study of Shenzhen City,China,this study focused on a quantitative method for analyzing the spatial processes involved in green infrastructure changes associated with rapid *** on RS,GIS and SPSS statistics software,the approach includes selection of the square analysis units and representative landscape metrics,quantification of the change types of landscape metrics in all analysis units through two indices and hierarchical cluster analysis of the above analysis units with different landscape metric change types(*** attributes).The analyses verify that there is a significant sequence of continuous changes in green infrastructure in *** are the perforation,the segmentation,the fragmentation,the evanescence and the filling-in processes,which have a good spatio-temporal correspondence with urbanization and reflect the synthetic influence of urban planning,government policies and *** with other studies on quantifying the spatial pattern,this study provides an alternative probe into linking the spatial pattern to spatial processes and the corresponding ecological processes in the *** spatio-temporal processes offer many opportunities for identifying,protecting and restoring key elements in an urban green infrastructure network for areas in the early stages of urbanization or for non-urbanized areas.

关键词： spatial process landscape metrics dynamic change green infrastructure urbanization

Porous S-doped carbon nitride foam with accelerated charge dynamics for synchronous photocatalytic hydrogen production and highly selective oxidation of amines

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第8期17卷 6860-6869页

作者： Yu He Aiping Wu Nan Wang Ying xie Chungui Tian honggang Fu Key Laboratory of Functional Inorganic Material Chemistry(Ministry of Education of the People’s Republic of China) Heilongjiang UniversityHarbin 150080China

Photocatalytic hydrogen evolution coupled with organic oxidation holds great promise for converting solar energy into high-valueadded chemicals,but it is hampered by sluggish charge dynamics and limited redox ***,a porous S-doped carbon nitride(S-C_(3)N_(4−y))foam assembled from ultrathin nanosheets with rich nitrogen vacancies was synthesized using a molecular selfassembly *** S dopants and N vacancies synergistically adjusted the band structure,facilitating light absorption and enhancing the oxidation ***,the ultrathin nanosheets and porous structure provided more exposed active sites and facilitated mass and charge ***,S-C_(3)N_(4−y) foam exhibited enhanced photocatalytic activities for synchronous hydrogen evolution(4960μmol/(h·g))and benzylamine oxidation to N-benzylidenebenzylamine(4885μmol/(h·g))with high selectivity of>99%,which were approximately 17.6 and 72.9 times higher than those of bulk CN,*** photocatalytic coupling pairing reaction promotes the water splitting by consuming H2O2,thereby improving the hydrogen evolution efficiency and achieving the production of high value-added *** study provides an effective route for regulating the morphology and band structure of carbon nitride for synthesizing highly valuable chemicals.

关键词： photocatalysis S-doped carbon nitride band structure regulation hydrogen evolution coupled with benzylamine oxidation reaction mechanism

A star-like photodetector for angle-based light sensing in 3D space

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第8期17卷 7567-7573页

作者： Qi Pan Sisi Chen hongfei xie Qiling Xu Meng Su Yanlin Song College of Chemistry Zhengzhou UniversityZhengzhou 450051China Key Laboratory of Green Printing CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of Sciences(ICCAS)Beijing Engineering Research Center of Nanomaterials for Green Printing TechnologyBeijing National Laboratory for Molecular Sciences(BNLMS)Beijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The development of three-dimensional(3D)space light angle detection is vital in optical technology for applications such as 3D imaging,computer vision,and augmented *** methods involve advanced sensors and algorithms,including time-offlight cameras,which need multiple cameras and light sources to improve ***,it is a great challenge to integrate these complex components into compact *** semiconductor structures offer optical resonance characteristics,enabling precise light–matter interaction regulation.A 3D star-like photodetector,fabricated using a template assistant printing strategy,demonstrates optical resonances of the subwavelength facade and the shielding effect of spatial *** achieves light angle detection with the resolution of 10°in vertical space and the resolution of 36°in horizontal space,making it a promising prototype for various applications.

关键词： photodetector light angle detection printing subwavelength structure shielding effect

Achievable Uplink Rate Analysis for Distributed Massive MIMO Systems with Interference from Adjacent Cells

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Communications 2017年第5期14卷 112-123页

作者： Xiangdong Jia Mangang xie Meng Zhou hongbo Zhu Longxiang Yang College of Computer Science and Engineering Northwest Normal University Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications

This work focuses on the multicell multi-user distributed massive MIMO(DM-MIMO)systems,of which each user is equipped with single antenna and the base stations(BSs)consists of distributed antenna units. We first investigate the arbitrary BS antenna topology scenario. The derivation indicates that in this case the achievable uplink rate of an arbitrary user in central cell depends on both the number of BS's antennas and the users' access distance to each distributed antenna unit(DAU). As a result,the performance analysis based on the derivations is difficult. To overcome this issue and achieve clearer insight,we then consider a circularly distributed BS antenna array and obtain the asymptotic uplink rate of an arbitrary user by considering the asymptotic case where the number of antennas of BSs tends to infinity. It is achieved that the asymptotic uplink rate only depends on the distance from users' position to the center of reference cell. The presented numerical results show clearly that the distributed massive MIMO systems outperform the centralized ones. Moreover,it is also achieved that the interference from the adjacent cells imposes great impact on system performance. Besides this,in numerical analysis the averageasymptotic uplink rate of a user is presented,which is free of the users' position and only depends on the radius of circular antenna arrays. It is achieved the maximum average uplink rate would be achieved when the radius of circularly distributed antenna array goes to its optimization location.

关键词： wireless communications massive MIMO distributed antenna array ergodic rate adjacent cell interference

Digital Element Earth

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2011年第1期85卷 1-16页

作者： xie Xuejing WANG Xueqiu CHENG Hangxin CHENG Zhizhong YAO Wensheng Institute of Geophysical and Geochemical Exploration CAGS 84 Jinguang Road Langfang Hebei Province 065000 China

The resources and environmental problems are the two most fundamental issues facing all nations in the world. Everything in and on the Earth - minerals, animals and plants -is made from one, or generally some combination of, chemical elements, which are scientifically listed in the periodic table. Thus it is important to understand the present abundance and spatial distribution of all the elements across the Earth＇s surface. Such kinds of data can only be obtained at present and for the foreseeable future by on-earth geochemical mapping at all scales. The 30-year efforts made by Chinese geochemists in carrying out multi-element, multi-media, multi-scale geochemical mapping projects to delineate 39-76 element distribution at home and abroad culminated in a successful case of high- quality geochemical data acquirement. The new idea for a four-level plan for global geochemical mapping was advanced to obtain global data in the foreseeable future and the collection of updated geochemical information. Such information needs to be easily accessible not only by the science community, but also by industry, agriculture, governments, and even individuals, by all who would make an effort to promote sustainable riving on our planet. The concept of a Digital Element Earth （DEE） fulfills the aims.

关键词： Digital Element Earth chemical elements geochemical mapping sustainable development

The correlation between expansion speed and magnetic field in solar flare ribbons

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2009年第11期52卷 1754-1759页

作者： xie WenBin WANG HaiMin JING Ju BAO XingMing ZHANG hongQi Key Laboratory of Solar Activity National Astronomical Observatories of ChinaBeijing 100012China Physics Department New Jersey Institute of TechnologyNewarkNJ07102USA Jilin Normal University Jilin 136000China

In this paper, we study the correlation between the expansion speed of two-ribbon flares and the magnetic field measured in the ribbon location, and compare such correlation for two events with different magnetic configurations. These two events are: an M1.0 flare in the quiet sun on September 12, 2000 and an X2.3 flare in Active Region NOAA 9415 on April 10, 2001. The magnetic configuration of the M1.0 flare is simple, while that of X2.3 event is complex. We have derived a power-law correlation between the ribbon expansion speed (V r) and the longitudinal magnetic field (Bz) with an empirical relationship V r = A×Bz-δ, where A is a constant and δ is the index of the power-law correlation. We have found that δ for the M1.0 flare in the simple magnetic configuration is larger than that for the X2.3 flare in the complex magnetic configuration.

关键词： solar activity solar flares solar magnetic field

An efficient projection defocus algorithm based on multi-scale convolution kernel templates

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science C(Computers and Electronics) 2013年第12期14卷 930-940页

作者： Bo ZHU Li-jun xie Guang-hua SONG Yao ZHENG School of Aeronautics and Astronautics Zhejiang University Center for Engineering and Scientific Computation Zhejiang University

The focal problems of projection include out-of-focus projection images from the projector caused by incomplete mechanical focus and screen-door effects produced by projection pixilation. To eliminate these defects and enhance the imaging quality and clarity of projectors, a novel adaptive projection defocus algorithm is proposed based on multi-scale convolution kernel templates. This algorithm applies the improved Sobel-Tenengrad focus evaluation function to calculate the sharpness degree of intensity equalization and then constructs multi-scale defocus convolution kernels to remap and render the defocus projection image. The resulting projection defocus corrected images can eliminate out-of-focus effects and improve the sharpness of uncorrected images. Experiments show that the algorithm works quickly and robustly and that it not only effectively eliminates visual artifacts and can run on a self-designed smart projection system in real time but also significantly improves the resolution and clarity of the observer's visual perception.

关键词： Projection focal Sobel-Tenengrad evaluation function Projector defocus Multi-scale convolution kernels

Temperature Distribution of Iron Ore Pellet Bed in Grate

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2012年第2期19卷 7-11页

作者： FENG Jun-xiao xie Zhi-yin CHEN Yan-mei School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China

The temperature distribution of iron ore pellet bed in grate has a significant effect on pellet production and quality control, but the related work is scarce. A well-designed test was successfully carried out by means of tracking measurement and the temperature distribution and variation in pellet layers were obtained. The effects of blast tem- perature, blast velocity and oxidation reaction on the pellet layer temperature were studied. According to the analy- sis, the inlet air temperature in the up-draught drying zone （UDD） and blast temperature in the Preheating I （PH I） zone should be raised, and the length of the down-draught drying zone （DDD） should be properly increased.

关键词： grate iron ore pellet bed temperature distribution industrial test

Non-injection gram-scale synthesis of cesium lead halide perovskite quantum dots with controllable size and composition

在线全文

学校读者我要写书评

暂无评论

Nano Research 2016年第7期9卷 1994-2006页

作者： Xu Chen Lucheng Peng Keke Huang Zhan Shi Renguo xie Wensheng Yang College of Chemistry Jilin University Changchun 130012 China State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 China

Metal-halide perovskites are novel optoelectronic materials that are considered good candidates for solar harvesting and light emitting applications. In this study, we develop a reproducible and low-cost approach for synthesizing high- quality cesium lead halide perovskite （CsPbX3, X = CI, Br, and I or C1/Br and I/Br） nanocrystals （NCs） by direct heating of precursors in octadecene in air. Experimental results show that the particle size and composition of as-prepared CsPbX3 nanocrystals can be successfully tuned by a simple variation of reaction temperature. The emission peak positions of the as-prepared nanocrystals can be conveniently tuned from the UV to the NIR （360-700 nm） region, and the quantum yield of the as-obtained samples （green and red emissions） can reach up to 87%. The structures and chemical compositions of the as-obtained NCs were characterized by transmission electron microscopy, X-ray diffraction, and elemental analysis. This proposed synthetic route can yield large amounts of high-quality NCs with a one-batch reaction, usually on the gram scale, and could pave the way for further applications of perovskite-based light-emitting and photovoltaic solar cells.

关键词： metal-halide perovskites gram-scale synthesis controllable size andcomposition optoelectronic materials