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A Numerical Calculation Algorithm of the Inclination Function Based on the Representation of SO(3) Group

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 137-148页

作者： Yu-xiao Wei Wen-lin tang Department of Geophysics School of Geology Engineering and GeomaticsChang’An UniversityXi’an710064China Key Laboratory of Electronics and Information Technology for Space Systems National Space Science CenterChinese Academy of SciencesBeijing100190China

In the determination of the Earth gravity field in satellite geodesy, the inclination functions represent the projection of data observed along the orbital plane of a satellite orbit into the sphere in the terrestial reference frame. The inclination functions in this work is studied from a group theoretical perspective. The inclination functions are proved to generate a representation of the SO(3) group. An orthogonal relation of the inclination functions is derived and some recurrence relations for the inclination functions are given, based on which an algorithm to calculate the inclination functions is proposed.

关键词： SO(3)group inclination function satellite geodesy representation of SO(3)

Interaction of Ca^(2+) and soil humic acid characterized by a joint experimental platform of potentiometric titration, UV–visible spectroscopy, and fluorescence spectroscopy

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Acta Geochimica 2021年第3期40卷 300-311页

作者： Haiming tang Baohua xiao Peiwen xiao State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of SciencesGuiyang 550081GuizhouChina University of Chinese Academy of Sciences Beijing 100049China

Rocky desertification has become a major environmental issue in the karst region of southwestern China.Karst rocky desertification was more severe in regions of limestone soil than in adjacent regions of other soils,despite the relatively higher soil organic matter(SOM)content in limestone soil.The underlying mechanism remains ambiguous.We speculated that the geochemical characteristics of limestone soils in the karst region plays an essential role,especially the high calcium content of limestone soil.To test this hypothesis,we collected limestone soil samples from a limestone soil profile in the southwestern China karst region and extracted humic acid(HA)from these limestone soil samples.We investigated the interaction of Ca^(2+)and three HA samples on a joint experimental platform,which consists of an automatic potentiometric titrator,a UV–visible spectrometer,and a Fluorescence spectrometer.HA solutions were titrated by Ca^(2+)and optical spectra of the HA solutions were monitored during the titration experiments.The results indicated that:(1)the interaction of Ca^(2+)and HA is a combined process of adsorption and complexation.Adsorption dominated the overall distribution behavior of Ca^(2+),which could be fit by Langmuir and Freundlich isotherm models.Complexation was distinguished only when the concentration of Ca2+is low;(2)the changes of UV–visible spectroscopy and excitation–emission matrix fluorescencespectroscopy spectra of HA samples when they were binding with Ca^(2+)implied the apparent molecular size and structure of HA became larger and more complex;(3)the combination of Ca^(2+)and HA plays an important role in the SOM preservation of limestone soils but the stability of the Ca–HA association was relatively weak.The present study draws attention to maintaining the relatively higher Ca^(2+)concentration in limestone soils in ecologic restoration attempts in karst regions.

关键词： Limestone soil Humic acid Calcium Interaction Titration UV–Vis EEM

SAR image despeckling with a multilayer perceptron neural network

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International Journal of Digital Earth 2019年第3期12卷 354-374页

作者： Xiao Tang Lei Zhang xiaoli Ding Department of Land Surveying and Geo-informatics The Hong Kong Polytechnic UniversityKowloonHong Kong

Speckle noise in synthetic-aperture radar (SAR) images severely hindersremote sensing applications;therefore, the appropriate removal ofspeckle noise is crucial. This paper elaborates on the multilayerperceptron (MLP) neural-network model for SAR image despeckling byusing a time series of SAR images. Unlike other filtering methods thatuse only a single radar intensity image to derive their parameters andfilter that single image, this method can be trained using archivedimages over an area of interest to self-learn the intensitycharacteristics of image patches and then adaptively determine theweights and thresholds by using a neural network for imagedespeckling. Several hidden layers are designed for feedforwardnetwork training, and back-propagation stochastic gradient descent isadopted to reduce the error between the target output and neuralnetwork output. The parameters in the network are automaticallyupdated in the training process. The greatest advantage of MLP is thatonce the despeckling parameters are determined, they can be used toprocess not only new images in the same area but also images incompletely different locations. Tests with images from TerraSAR-X inselected areas indicated that MLP shows satisfactory performance withrespect to noise reduction and edge preservation. The overall imagequality obtained using MLP was markedly higher than that obtainedusing numerous other filters. In comparison with other recentlydeveloped filters, this method yields a slightly higher image quality,and it demonstrates the powerful capabilities of computer learningusing SAR images, which indicate the promising prospect of applyingMLP to SAR image despeckling.

关键词： Multilayer perceptron synthetic aperture radar despeckling neural network

C^(0) conjugacy between PM functions with nonmonotonicity height equal to 1

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Science China Mathematics 2021年第9期64卷 1993-2006页

作者： Xiao Tang School of Mathematics Sichuan UniversityChengdu610064China

In this paper,a topological classification of piecewise monotone functions(abbreviated as PM functions)with nonmonotonicity height equal to 1 which are strictly increasing on their characteristic intervals and have fi... 详细信息

关键词： topological conjugacy PM function nonmonotonicity height piecewise construction

Cnoidal waves and their soliton limits in single mode fiber lasers

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Photonics Research 2024年第3期12卷 543-551页

作者： xiao HU TUPEI CHEN SEONGWOO YOO DINGYUAN tang Julong College Shenzhen Technology UniversityShenzhen 518118China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore

Cnoidal waves are a type of nonlinear periodic wave solutions of the nonlinear dynamic equations.They are well known in fluid dynamics,but it is not the case in optics.In this paper we show both experimentally and numerically that cnoidal waves could be formed in a fiber laser either in the net normal or net anomalous cavity dispersion regime,especially because,as the pump power is increased,the formed cnoidal waves could eventually evolve into a train of bright(in the net anomalous cavity dispersion regime)or dark(in the net normal cavity dispersion regime)solitons.Numerical simulations of the laser operation based on the extended nonlinear Schrödinger equation(NLSE)have well reproduced the experimental observations.The result not only explains why solitons can still be formed in a fiber laser even without mode locking but also suggests a new effective way of automatic stable periodic pulse train generation in lasers with a nonlinear cavity.

关键词： fiber pump mode

Physical-data Fusion Modeling Method for Energy Consumption Analysis of Smart Building

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Journal of Modern Power Systems and Clean Energy 2022年第2期10卷 482-491页

作者： xiao Han Chaohai Zhang Yi tang Yujian Ye the Jiangsu Key Laboratory of New Energy Generation and Power Conversion Nanjing University of Aeronautics and AstronauticsNanjing 211106China the School of Electrical Engineering Southeast UniversityNanjing 210096China the Department of Electrical and Electronic Engineering Imperial College LondonLondonU.K.

The energy consumption of buildings accounts for approximately 40%of total energy consumption.An accurate energy consumption analysis of buildings can not only promise significant energy savings but also help estimate the demand response potential more accurately,and consequently brings benefits to the upstream power grid.This paper proposes a novel physical-data fusion modeling(PFM)method for modeling smart buildings that can accurately assess energy consumption.First,a thermal process model of buildings and an electrical load model that focus on building heating,ventilation,and air conditioning(HVAC)systems are presented to analyze the thermal-electrical conversion process of energy consumption of buildings.Second,the PFM method is used to improve the accuracy of the energy consumption analysis model for buildings by modifying the parameters that are difficult to measure in the physical model(i.e.,it effectively modifies the electrical load model based on the proposed PFM method).Finally,case studies involving a real-world dataset recorded in a high-tech park in Changzhou,China,demonstrate that the proposed method exhibits superior performance with respect to the traditional physical modeling(TPM)method and data-driven modeling(DDM)method in terms of the achieved accuracy.

关键词： Smart building physical-data fusion modeling method energy consumption precision model thermal-electrical conversion.

Radiative properties of alumina/aluminum particles and influence on radiative heat transfer in solid rocket motor

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Chinese Journal of Aeronautics 2022年第2期35卷 98-116页

作者： Xuefan HAO Hu ZHANG xiao HOU Guihua tang State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an 710049China Shaanxi Key Laboratory of Environment and Control for Flight Vehicle Xi'an Jiaotong UniversityXi’an 710049China College of Astronautics Northwestern Polytechnical UniversityXi’an 710072China Key Laboratory of Thermo-Fluid Science and Engineering Ministry of EducationXi’an Jiaotong UniversityXi’an 710049China

The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties of alumina particles while the study considering the presence of aluminum is lacking.In addition,the thermal radiation inside the SRM with consideration of the participating particles is seldom studied.In this work,the multiscale method of predicting the thermal environment inside SRMs is established from the particle radiation at microscale to the twophase flow and heat transfer at macroscale.The effective gray radiative properties of individual particles(alumina,aluminum,and hybrid alumina/aluminum)and particles cloud are investigated with the Mie theory and approximate method.Then a numerical method for predicting the thermal environment inside SRMs with considering particle radiation is established and applied in a subscale motor.The convective and radiative heat flux distributions along inner wall of motor are obtained,and it is found that the heat transfer in the combustion chamber is dominated by thermal radiation and the radiative heat flux is essentially a constant of 5.6–6.8 MW/m^(2).The convective heat transfer plays a dominant role in the nozzle and the heat flux reaches the maximum value of 11.2 MW/m^(2) near the throat.As the combustion efficiency of aluminum drops,the radiative heat flux remains unchanged in most regions and increases slightly along the diverging section wall of the nozzle.

关键词： Alumina Aluminum Condensed phase particle Radiative heat transfer Radiative properties Solid rocket motor

Reduction of N2O emissions by DMPP depends on the interactions of nitrogen sources(digestate vs. urea) with soil properties

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Journal of Integrative Agriculture 2023年第1期22卷 251-264页

作者： LI Hao-ruo SONG xiao-tong Lars RBAKKEN JU xiao-tang College of Resources and Environmental Sciences China Agricultural UniversityBeijing 100193P.R.China State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085P.R.China College of Tropical Crops Hainan UniversityHaikou 570228P.R.China Faculty of Chemistry Biotechnology and Food ScienceNorwegian University of Life Science(NMBU)Ås 1430Norway

The inhibition of nitrification by mixing nitrification inhibitors(NI)with fertilizers is emerging as an effective method to reduce fertilizer-induced nitrous oxide(N_(2)O)emissions.The additive 3,4-dimethylpyrazole phosphate(DMPP)apparently inhibits ammonia oxidizing bacteria(AOB)more than ammonia oxidizing archaea(AOA),which dominate the nitrification in alkaline and acid soil,respectively.However,the efficacy of DMPP in terms of nitrogen sources interacting with soil properties remains unclear.We therefore conducted a microcosm experiment using three typical Chinese agricultural soils with contrasting pH values(fluvo-aquic soil,black soil and red soil),which were fertilized with either digestate or urea in conjunction with a range of DMPP concentrations.In the alkaline fluvo-aquic soil,fertilization with either urea or digestate induced a peak in N_(2)O emission(60μg N kg^(-1)d^(-1))coinciding with the rapid nitrification within 3 d following fertilization.DMPP almost eliminated this peak in N_(2)O emission,reducing it by nearly 90%,despite the fact that the nitrification rate was only reduced by 50%.In the acid black soil,only the digestate induced an N_(2)O emission that increased gradually,reaching its maximum(20μg N kg^(-1)d^(-1))after 5–7 d.The nitrification rate and N_(2)O emission were both marginally reduced by DMPP in the black soil,and the N_(2)O yield(N_(2)O-N per NO2–+NO3–-N produced)was exceptionally high at 3.5%,suggesting that the digestate induced heterotrophic denitrification.In the acid red soil,the N_(2)O emission spiked in the digestate and urea treatments at 50 and 10μg N kg^(-1)d^(-1),respectively,and DMPP reduced the rates substantially by nearly 70%.Compared with 0.5%DMPP,the higher concentrations of DMPP(1.0 to 1.5%)did not exert a significantly(P<0.05)better inhibition effect on the N_(2)O emissions in these soils(either with digestate or urea).This study highlights the importance of matching the nitrogen sources,soil properties and NIs to achieve a high efficiency of N_(2)O emission

关键词： nitrous oxide digestate urea nitrification inhibitors DMPP alkaline soils acid soils

Dilemmas in diagnosis and management of hemophagocytic lymphohistiocytosis in children

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World Journal of Pediatrics 2020年第4期16卷 333-340页

作者： xiao-Jun Xu Yong-Min tang Division of Hematology-Oncology Children’s HospitalZhejiang University School of MedicineKey Laboratory of Reproductive Genetics of Ministry of EducationZhejiang UniversityHangzhou310003China

Background Hemophagocytic lymphohistiocytosis(HLH)is a life-threatening entity which is characterized by severe hyperinflammation.Now the HLH-2004 protocol has been widely accepted and clinically used;however,many questions still remain in clinical practice.In this review,we discuss the dilemmas in the diagnosis and treatment of HLH in children.Data sources Original research for articles and literature reviews published in PubMed was carried out using the key term“hemophagocytic lymphohistiocytosis”.Results As the gene sequencing technology progresses,the range of causal mutations and primary HLH has been redefined.The monoallelic variants may contribute to the pathogenesis of the disease.Many conditions without defective cytotoxicity of T or NK cells may lead to HLH,such as primary immunodeficiency(PID)and dysregulated immune activation or proliferation(DIAP).HLH shares overlapping clinical and laboratory characteristics with severe sepsis,but usually the single values are more pronounced in HLH than sepsis.H score is another approach to help the diagnosis of secondary HLH.Specific Th1/Th2 cytokine patterns are very helpful tools to differentiate HLH(reactivation of HLH)from sepsis.Moreover,it also has been used successfully to stratify the therapy intensity.The treatment of HLH should consider underlying diseases,triggers and severity.HLH-94 is recommended for patients who need etoposide-based therapy.Conclusions Dramatic progress has been made during the past decades in understanding the pathophysiology of HLH.However,diagnosis and treatment of HLH remain with many dilemmas because of the heterogeneous nature of the disease.Better understanding new gene defects and more effective diagnostic approaches and salvage regimens are goals for the future.

关键词： Cytokine Hemophagocytic lymphohistiocytosis Sepsis Transplantation