检索结果-南通市图书馆

Prediction of soil organic carbon stock combining Sentinel-1 and Sentinel-2 images in the Zoige Plateau, the northeastern Qinghai-Tibet Plateau

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2024年第2期13卷 165-176页

作者： Junjie Lei Changli Zeng Lv Zhang xiaogang Wang Chanhua Ma Tao Zhou Benjamin Laffitte Ke Luo Zhihan Yang Xiaolu tang State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Sichuan Academy of Geological Survey Sichuan Institute of Nuclear Geological Survey College of Earth Sciences Chengdu University of Technology Tianfu Yongxing Laboratory

Background Soil organic carbon（SOC） is a critical component of the global carbon cycle, and an accurate estimate of regional SOC stock（SOCS） would significantly improve our understanding of SOC sequestration and cycles. Zoige Plateau, locating in the northeastern Qinghai-Tibet Plateau, has the largest alpine marsh wetland worldwide and exhibits a high sensitivity to climate fluctuations. Despite an increasing use of optical remote sensing in predicting regional SOCS, optical remote sensing has obvious limitations in the Zoige Plateau due to highly cloudy weather, and knowledge of on the spatial patterns of SOCS is limited. Therefore, in the current study, the spatial distributions of SOCS within 100 cm were predicted using an XGBoost model—a machine learning approach, by integrating Sentinel-1, Sentinel-2 and field observations in the Zoige *** The results showed that SOC content exhibited vertical distribution patterns within 100 cm, with the highest SOC content in topsoil. The tenfold cross-validation approach showed that XGBoost model satisfactorily predicted the spatial patterns of SOCS with a model efficiency of 0.59 and a root mean standard error of 95.2 Mg ha-1. Predicted SOCS showed a distinct spatial heterogeneity in the Zoige Plateau, with an average of 355.7 ± 123.1 Mg ha-1within 100 cm and totaled 0.27 × 10～9 Mg *** High SOC content in topsoil highlights the high risks of significant carbon loss from topsoil due to human activities in the Zoige Plateau. Combining Sentinel-1 and Sentinel-2 satisfactorily predicted SOCS using the XGBoost model, which demonstrates the importance of selecting modeling approaches and satellite images to improve efficiency in predicting SOCS distribution at a fine spatial resolution of 10 m. Furthermore, the study emphasizes the potential of radar（Sentinel-1） in developing SOCS mapping, with the newly developed fine-resolution mapping having important applications in land management, ecological resto

关键词： SOC Vegetation index Texture XGBoost Sentinel-1 Sentinel-2

Platform Competition for Advertisers and Viewers in Media Markets with Endogenous Content and Advertising

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2020年第1期29卷 36-54页

作者： xiaogang Lin Rui Hou Yongwu Zhou School of Management Guangdong University of TechnologyGuangzhou 510520China School of Business Administration South China University of TechnologyGuangzhou 510641China

In this paper,we investigate two competing pay-tv platforms or free-to-air media platforms that consist of two groups of agents:viewers and *** pay-tv platforms can receive revenues from charging viewers pay-per-view prices and advertising,while the free-to-air platforms can only obtain all incomes from *** discuss and compare advertising intensities and program content provisions of the two competing media *** findings show that if the extent to which viewers dislike advertising(the nuisance for advertising)is more massive than the marginal benefit that advertisers receive from an additional viewer,the pay-tv stations tend to maximally differentiate their program content and charge the viewers higher pay-per-view *** the nuisance approaches to the marginal benefit,however,both stations should offer similar program content,and charge the viewers lower prices under certain ***,if both platforms provide duplicated content,they should subsidize the *** contrast,we show that the free-to-air media platforms never duplicate program content with a positive nuisance for advertising,and tend to offer maximal differentiated content if the nuisance is sufficiently ***,we reveal that if the viewers greatly dislike advertising(care less about advertising),the advertising volume of the pay-tv platforms is lower(higher)than that of the free-to-air ***,we extend our base model to the case in which a pay-tv platform competes against a free-to-air station,and numerically show that the profit of the pay-tv platform may be larger or smaller than that of the free-to-air station.

关键词： Media platforms two-sided markets content provision advertising intensity product differentiation

Clustering routing algorithm of wireless sensor networks based on Bayesian game

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

Journal of Systems Engineering and Electronics 2012年第1期23卷 154-159页

作者： Gengzhong Zheng Sanyang Liu xiaogang Qi School of Computer Science and Technology Xidian University Xi＇an 710071 R R. China Department of Mathematics and Information Technology Hanshan Normal University Chaozhou 521041 R R. China School of Science Xidian University Xi＇an 710071 R R. China

To avoid uneven energy consuming in wireless sen- sor networks, a clustering routing model is proposed based on a Bayesian game. In the model, Harsanyi transformation is introduced to convert a static game of incomplete information to the static game of complete but imperfect information. In addition, the existence of Bayesian nash equilibrium is proved. A clustering routing algorithm is also designed according to the proposed model, both cluster head distribution and residual energy are considered in the design of the algorithm. Simulation results show that the algorithm can balance network load, save energy and prolong network lifetime effectively.

关键词： wireless sensor networks (WSNs) clustering routing Bayesian game energy efficiency.

Flexible-on-rigid heteroepitaxial metal-organic frameworks induced by template lattice change

在线全文

学校读者我要写书评

暂无评论

Nano Research 2022年第5期15卷 4693-4699页

作者： xiaogang Wang Han Cheng XianZheng Zhang Key Laboratory of Biomedical Polymers of Ministry of Education&Department of Chemistry Wuhan UniversityWuhan 430072China

Hybrid-phase metal-organic frameworks(MOFs)are a class of intriguing heterostructures for diverse applications,the properties of which are governed by their chemical composition,framework topology,and ***,we report the structural and morphological evolution of flexible MOFs induced by the lattice change of template during heteroepitaxial *** demonstrate that the epitaxially grown flexible Fe-MOFs can be varied from one structure to another to adapt to the lattice of the template ***,flexible Fe-MOFs with similar chemical compositions and topology can be epitaxially grown on different Zr-MOFs over huge lattice constant *** also demonstrate that the morphology of the heterostructures is affected by the degree of lattice difference between the template MOFs and the epitaxial *** reported results could pave the way toward the rational design of hybrid-phase MOFs guided by the principles of reticular chemistry.

关键词： metal-organic framework(MOF) heteroepitaxial growth MOF-on-MOF structural evolution heterostructure

New optimized flux difference schemes for improving high-order weighted compact nonlinear scheme with applications

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

Applied Mathematics and Mechanics(English Edition) 2021年第3期42卷 405-424页

作者： Shichao ZHENG xiaogang DENG Dongfang WANG College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

To improve the spectral characteristics of the high-order weighted compact nonlinear scheme(WCNS),optimized flux difference schemes are *** disadvantages in previous optimization routines,i.e.,reducing formal orders,or extending stencil widths,are avoided in the new optimized schemes by utilizing fluxes from both cell-edges and *** are implemented with Fourier analysis for linear schemes and the approximate dispersion relation(ADR)for nonlinear *** difference schemes are restored near discontinuities to suppress numerical oscillations with use of a shock sensor based on smoothness *** results of several benchmark numerical tests indicate that the new optimized difference schemes outperform the classical schemes,in terms of accuracy and resolution for smooth wave and vortex,especially for long-time *** optimized schemes increases the total CPU time by less than 4%.

关键词： optimization flux difference weighted compact nonlinear scheme(WCNS) resolution spectral error

A review of the bio-tribology of medical devices

在线全文

学校读者我要写书评

暂无评论

Friction 2022年第1期10卷 4-30页

作者： xiaogang ZHANG Yali ZHANG Zhongmin JIN School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049China School of Mechanical Engineering University of Leeds.Leeds LS29JTUK

Numerous medical devices have been applied for the treatment or alleviation of various *** issues widely exist in those medical devices and play vital roles in determining their performance and service *** this review,the bio-tribological issues involved in commonly used medical devices are identified,including artificial joints,fracture fixation devices,skin-related devices,dental restoration devices,cardiovascular devices,and surgical *** current understanding of the bio-tribological behavior and mechanism involved in those devices is *** advances in the improvement of tribological properties are *** and future developments for the prospective of bio-tribological performance are highlighted.

关键词： bio-tribology medical devices wear friction

Controlled patterning of upconversion nanocrystals through capillary force

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2020年第5期38卷 546-551页

作者： Yiming Wu Jiahui Xu xiaogang Liu Department of Chemistry National University of SingaporeU7543Singapore The N.1 Institute for Health National University of Singapore117456Singapore

Lanthanide-doped upconversion nanoparticles(UCNPs)can absorb near-infrared photons and convert them into visible and ultraviolet *** nanomaterials possess extraordinary optical performance and hold potential as active platforms for a variety of technological *** ability to fabricate highly ordered nanoparticle-based photonic elements over a large area is of fundamental significance for luminescence *** all the efforts made,however,large-area spatial patterning of UCNPs into ordered arrays with high controllability remains a *** this study,we report a highthroughput strategy to pattern optical nanomaterials through the use of polymer microspheres and templated assembly of *** technique utilizes capillary force to drive hybrid clusters into the physical template,resulting in large-area,spatially ordered arrays of *** findings reported in this work may promote the development of novel nonlinear optical devices,such as solid-state laser arrays,high-density optical storage,and anti-counterfeiting labels.

关键词： Upconversion nanoparticles Self-assembly Patterning Rare earths

Exclusive Hypothesis Testing for Cox's Proportional Hazards Model

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第5期37卷 2157-2172页

作者： WU Qiang TONG Xingwei DUAN xiaogang School of Statistics Beijing Normal UniversityBeijing 100875China

Exclusive hypothesis testing is a new and special class of hypothesis *** kind of testing can be applied in survival analysis to understand the association between genomics information and clinical information about the survival ***,it is well known that Cox's proportional hazards model is the most commonly used model for regression analysis of failure *** this paper,the authors consider doing the exclusive hypothesis testing for Cox's proportional hazards model with right-censored *** authors propose the comprehensive test statistics to make decision,and show that the corresponding decision rule can control the asymptotic TypeⅠerrors and have good powers in *** numerical studies indicate that the proposed approach works well for practical situations and it is applied to a set of real data arising from Rotterdam Breast Cancer Data study that motivated this study.

关键词： Comprehensive test statistics Cox’s proportional hazards model exclusive hypothesis testing right-censored data Type I error

Surface activation of colloidal indium phosphide nanocrystals

在线全文

学校读者我要写书评

暂无评论

Nano Research 2017年第3期10卷 941-958页

作者： Yang Li Chaodan Pu xiaogang Peng Center for Chemistry of Novel & High-Performance Materials Department of Chemistry Zhejiang University Hangzhou 310027 China

Against general wisdom in crystallization, the nucleation of InP and III-V quantum dots （QDs） often dominates their growth. Systematic studies on InP QDs identified the key reason for this： the dense and tight alkanoate-ligand shell around each nanocrystal. Different strategies were explored to enable necessary ligand dynamics--i.e., ligands rapidly switching between being bonded to and detached from a nanocrystal upon thermal agitation--on nanocrystals to simultaneously retain colloidal stability and allow appreciable growth. Among all the surface-activation reagents tested, 2,4-diketones （such as acetylacetone） allowed the full growth of InP QDs with indium alkanoates and trimethylsilylphosphine as precursors. While small fatty acids （such as acetic acid） were partially active, common neutral ligands （such as fatty amines, organophosphines, and phosphine oxides） showed limited activation effects. The existing amine-based synthesis of InP QDs was activated by acetic acid formed in situ. Surface activation with common precursors enabled the growth of InP QDs with a distinguishable absorption peak between ~450 and 650 nm at mild temperatures （140-180 ~C）. Furthermore, surface activation was generally applicable for InAs and III-V based core/shell QDs.

关键词： quantum dots nanocrystals indium phosphide surface