检索结果-南通市图书馆

Wind speed inversion and in-orbit assessment of the imaging altimeter on Tiangong-2 space station

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2020年第12期39卷 114-120页

作者： Youguang Zhang Qingliu Bao Mingsen Lin Shuyan lang Key Laboratory of Space Ocean Remote Sensing and Application National Satellite Ocean Application ServiceBeijing 100081China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Beijing Piesat Information Technology Co. Ltd.Beijing 100195China

Imaging altimeter(IALT)is a new type of radar altimeter *** contrast to the conventional nadir-looking altimeters,such as HY-2 A altimeter,Jason-1/2,and TOPEX/Poseidon,IALT observes the earth surface at low incident angles(2.5°–8°),so its swath is much wider and its spatial resolution is much higher than the previous *** paper presents a wind speed inversion method for the recently launched IALT onboard Tiangong-2 space *** the current calibration results of IALT do not agree well with the well-known wind geophysical model function at low incidence angles,a neural network is used to retrieve the ocean surface wind speed in this *** wind speed inversion accuracy is evaluated by comparing with the ECMWF reanalysis wind speed,buoy wind speed,and in-situ ship *** results show that the retrieved wind speed bias is about–0.21 m/s,and the root-mean-square(RMS)error is about 1.85 m/*** wind speed accuracy of IALT meets the performance requirement.

关键词： imaging altimeter ocean surface wind speed inversion accuracy analysis in-orbit assessment

Rutin pretreatment promotes microglial M1 to M2 phenotype polarization

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2021年第12期16卷 2499-2504页

作者： Guang-Ping lang Can Li Ying-Ying Han Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education Zunyi Medical UniversityZunyiGuizhou ProvinceChina Special Key Laboratory of Oral Diseases Research Higher Education Institutions of Guizhou ProvinceZunyi Medical UniversityZunyiGuizhou ProvinceChina

Microglial cells are important resident innate immune components in the central nervous system that are often activated during *** microglia can display one of two phenotypes,M1 or M2,which each play distinct roles in ***,a dietary flavonoid,exhibits protective effects against ***,whether rutin is able to influence the M1/M2 polarization of microglia remains *** this study,in vitro BV-2 cell models of neuroinflammation were established using 100 ng/mL lipopolysaccharide to investigate the effects of 1-hour rutin pretreatment on microglial *** results revealed that rutin pretreatment reduced the expression of the proinflammatory cytokines tumor necrosis factor-α,interleukin-1β,and interleukin-6 and increased the secretion of *** pretreatment also downregulated the expression of the M1 microglial markers CD86 and inducible nitric oxide synthase and upregulated the expression of the M2 microglial markers arginase 1 and *** pretreatment inhibited the expression of Toll-like receptor 4 and myeloid differentiation factor 88 and blocked the phosphorylation of I kappa B kinase and nuclear factor-kappa *** results showed that rutin pretreatment may promote the phenotypic switch of microglia M1 to M2 by inhibiting the Toll-like receptor 4/nuclear factor-kappa B signaling pathway to alleviate lipopolysaccharide-induced neuroinflammation.

关键词： BV-2 cells flavonoid M1 microglia M2 microglia microglia activation microglia polarization neuroinflammation proinflammatory cytokines rutin TLR-4 signaling

Differences between CMIP6 and CMIP5 Models in Simulating Climate over China and the East Asian Monsoon

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2020年第10期37卷 1102-1118,I0002-I0017页

作者： Dabang JIANG Dan HU Zhiping TIAN and Xianmei lang Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China University of Chinese Academy of Sciences Beijing 100049China

We compare the ability of coupled global climate models from the phases 5 and 6 of the Coupled Model Intercomparison Project(CMIP5 and CMIP6,respectively)in simulating the temperature and precipitation climatology and interannual variability over China for the period 1961–2005 and the climatological East Asian monsoon for the period 1979–*** 92 models are able to simulate the geographical distribution of the above variables reasonably *** with earlier CMIP5 models,current CMIP6 models have nationally weaker cold biases,a similar nationwide overestimation of precipitation and a weaker underestimation of the southeast–northwest precipitation gradient,a comparable overestimation of the spatial variability of the interannual variability,and a similar underestimation of the strength of winter monsoon over northern *** comparison indicates that models have improved from CMIP5 to CMIP6 for climatological temperature and precipitation and winter monsoon but display little improvement for the interannual temperature and precipitation variability and summer *** ability of models relates to their horizontal resolutions in certain *** the multi-model arithmetic mean and median display similar skills and outperform most of the individual models in all considered aspects.

关键词： global climate models climatology interannual variability model performance China East Asia

Tf_2O-TMDS combination for the direct reductive transformation of secondary amides to aldimines,aldehydes, and/or amines

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2016年第12期59卷 1638-1644页

作者： Qi-Wei lang Xiu-Ning Hu Pei-Qiang Huang Department of Chemistry Fujian Provincial Key Laboratory of Chemical Biology Collaborative Innovation Center of Chemistry for Energy Materials College of Chemistry and Chemical Engineering Xiamen University

The direct partial reduction of highly stable secondary amides to more reactive aldimines and aldehydes is a challenging yet highly demanding transformation. In this context, only three methods have been reported. We report herein an improved version of the Charette's method. Our protocol consists of activation of secondary amides with triflic anhydride/2-fluoropyridine,and partial reduction of the resulting intermediates with 1,1,3,3-tetramethyldisiloxane(TMDS), which delivered aldimines or aldehydes upon acidic hydrolysis. Aromatic amides were reduced to the corresponding aldimines in 85%–100% NMR yields,and yields(NMR) from aliphatic amides were 72%–86%. Acidic hydrolysis of the aldimine intermediates afforded, in one-pot,the corresponding aldehydes in 80%–96% yields. A simple protocol was established to isolate labile aldimines in pure form in92%–96% yields. The improved method gave generally higher yields as compared to the known ones, and features the use of cheaper and more atom-economical TMDS as a chemoselective reducing agent. In addition, a convenient extraction protocol has been established to allow the isolation of amines, which constitutes a mild method for the N-deacylation of amides, another highly desirable transformation. The extended method retains the advantages of the original method of Charette in terms of mild conditions, good functional group tolerance, and excellent chemoselectivity.

关键词： secondary amides amide activation partial reduction aldimines N-deacylation

Complete moment convergence for weighted sums of widely orthant-dependent random variables and its application in nonparametric regression models

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2022年第4期17卷 571-590页

作者： Lu CHENG Junjun lang Yan SHEN Xuejun WANG School of Mathematical Sciences Anhui UniversityHefei230601China

We establish some results on the complete moment convergence for weighted sums of widely orthant-dependent(WOD)random variables,which improve and extend the corresponding results of ***,***,and ***[***.,2019,13(1):251–260].As an application of the main results,we investigate the complete consistency for the estimator in a nonparametric regression model based on WOD errors and provide some simulations to verify our theoretical results.

关键词： Widely orthant-dependent random variables complete moment convergence nonparametric regression model

Unsteady characteristic research on aerodynamic interaction of slotted wingtip in flapping kinematics

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

Chinese Journal of Aeronautics 2022年第4期35卷 82-101页

作者： Dan LIU Bifeng SONG Wenqing YANG Dong XUE Xinyu lang School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Yangtze River Delta Research Institute.Northwestern Polytechnical University Taiccing 215400China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China

The slotted wingtip structure of birds is considered to be the product of improving flight efficiency in the process of evolution. It can change the vortex structure of wingtip and improve aerodynamic efficiency. This paper reports a numerical investigation of slotted wing configuration undergoing bio-inspired flapping kinematics(consisting of plunging and in-line movement)extracted from a free-flying bald eagle wing. The aim is to eluci-date the collective mechanism of the flow generated by slotted tips and the lift contribution of each tip. Specifi-cally, the objective of the study is to determine how changes in the wing spacing affect the resulting aerodynamic interaction between the slotted tips and how that affects the force generation and efficiency. Changes in the phase angle between the flapping motions of slotted tips, as well as the spacings among them,can affect the resulting vortex inter-actions. The rear tips often operates in the wake of the frontal tips and, meanwhile, the vortex generated by the movement of the rear tips promote the frontal *** interaction of vortices in time and space leads to wing-wing interference and the flow around slotted tips becomes complicated and unstable. The innovative study of wingtip slot in unsteady state leads us to find that the aerodynamic interaction among slotted tips makes the overall lift characteristic better than that of the unslotted wings. The slotted wing configuration can efficiently convert more energy into lift. As the flapping frequency increases, the collective feature of slotted wing with constantly changing gaps can be more advantageous to enhance lift-generation performance.

关键词： Aerodynamic interaction Aerodynamic mechanism Flapping Unsteady behavior Wingtip slots

Analysis on the Mutation and Time-Varying Characteristics of Coal Price System Evolution from the Perspective of Finance

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2021年第4期34卷 1501-1521页

作者： CHAI Jian LEI Junchan SHI Huiting ZHANG Xuejun lang Meiling School of Economics and Management Xidian UniversityXi'an 710126China

Coal is essential to ensure China’s energy *** sudden or gradual change of coal price reflects the degree of disequilibrium or expected disequilibrium of coal supply and demand,which will not be conducive to energy ***,it is important to analyze the change points of coal price and explore the reason of the price *** paper analyses the coal price from January2008 to June 2019 as the perspective of the financial ***,the PPM-DBSCAN model is used to identify the mutation point of coal price ***,path analysis is used to extract the core driving factors that affect coal ***,the authors construct a time-varying and time-lag effect analysis model for structural changes of coal price based on the TVP-VAR *** results show that there are 11 mutation points of coal price *** market factors,coal supply and demand and alternative factors are the reasons of coal price *** authors find that the imbalance of coal supply and demand in traditional view cannot fully explain the fluctuation of coal *** impact of the financial market and non-thermal power generation have more influence on the coal price.

关键词： Coal price financial market mutation

A new scattering similarity based metric for ship detection in polarimetric synthetic aperture radar image

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2020年第5期39卷 145-150页

作者： Haitao lang Yunhong Tao Lihui Niu Hongji Shi College of Mathematics and Physics Beijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of Environmentally Harmful Chemicals Analysis Beijing University of Chemical TechnologyBeijing 100029China

A new paradigm for ship detection in polarimetric synthetic aperture radar(Pol-SAR)image is *** firstly utilize the scattering similarity parameters to investigate the differences of scattering mechanism between ships and sea *** on these differences,we propose a novel ship detection metric,denoted as the scattering similarity based metric(SSM),to conduct ship detection *** distribution model of SSM metric is investigated and modeled by kernel density estimation(KDE).Based on the statistical distribution,an adaptive constant false alarm rate(CFAR)detection scheme is *** compare the proposed SSM with two classic polarimetric metrics,i.e.,the polarimetric cross-entropy(PCE)and the reflection symmetry metric(RSM).The experimental results conducted on C-band RADARSAT-2 Pol-SAR data demonstrate the feasibility and advantage of the proposed SSM metric both in sea clutter modeling and in ship detection.

关键词： Pol-SAR scattering similarity KDE CFAR ship detection

Enhance hydrates formation with stainless steel fiber for high capacity methane storage

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2022年第10期50卷 435-443页

作者： Zhixia Deng Shuanshi Fan Yanhong Wang Xuemei lang Gang Li School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou 510640China Guangdong Engineering Technology Research Center of Advanced Insulating Coating Zhuhai 519175China Institute of Modern Industrial Innovation South China University of TechnologyZhuhai 519175China Key Laboratory of Fuel Cell Technology of Guangdong Province Guangzhou 510640China

In order to realize efficient gas storage of hydrate,stainless steel fiber(SSF)was added to 0.03%(mass)sodium dodecyl sulfate(SDS)solution for gas storage *** can not only improve the problem that hydration heat cannot be removed effectively in the hydration process,but also improve gas storage speed and gas storage by increasing hydrate nucleation *** the experimental conditions(273.2 K,5-9 MPa),the peaks of temperature rise in SDS+SSF systems were found to become much smaller than those in SDS *** maximum gas storage rate and the maximum methane uptake of SSF+SDS system reached 9.89-24.90 cm^(3)·g^(-1)·min^(-1) and 178.65-200.89 cm^(3)·(g H_(2)O)-1,*** with the surfactant SDS solution without SSF,they increased by 10.47%-33.22%and 9.16%-25.36%,*** effect of SSF length on gas storage performance was *** to the continuous thermal conduction network,longer SSF showed a higher gas storage capacity and methane uptake rate compared with shorter *** the same time,compared with other metal fillers,SSF+SDS not only had excellent gas storage performance,but also the amount of SSF(0.1 g·ml^(-1))was only 7.6%of foamed aluminum,and the volume gas storage density was increased by 145.4%.The use of stainless steel fiber made the best use of the thermal conductivity of metal,reduced the amount of metal used,and improved the volume density and mass density of gas storage.

关键词： Methane Stainless steelfiber Gas storagecapacity Hydrate Gas storagerate Heat transfer