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Stochastically Perturbed Parameterizations for the Process-Level Representation of Model Uncertainties in the CMA Global Ensemble Prediction System

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Journal of Meteorological Research 2022年第5期36卷 733-749页

作者： fei peng Xiaoli LI Jing CHEN CMA Earth System Modeling and Prediction Centre China Meteorological Administration(CMA)Beijing 100081 State Key Laboratory of Severe Weather China Meteorological AdministrationBeijing 100081 National Meteorological Centre China Meteorological AdministrationBeijing 100081

To represent model uncertainties at the physical process level in the China Meteorological Administration global ensemble prediction system(CMA-GEPS),a stochastically perturbed parameterization(SPP)scheme is developed by perturbing 16 parameters or variables selected from three physical parameterization schemes for the planetary boundary layer,cumulus convection,and cloud *** chosen quantity is perturbed independently with temporally and spatially correlated perturbations sampled from log-normal *** of the SPP scheme on CMA-GEPS are investigated comprehensively by using the stochastically perturbed parametrization tendencies(SPPT)scheme as a *** the absence of initial-condition perturbations,perturbation structures introduced by the two schemes are investigated by analyzing the ensemble spread of three forecast variables’physical tendencies and perturbation energy in ensembles generated by the separate use of SPP and *** is revealed that both schemes yield different perturbation structures and can simulate different sources of model *** initialcondition perturbations are activated,the influences of the two schemes on the performance of CMA-GEPS are assessed by calculating verification scores for both upper-air and surface *** improvements in ensemble reliability and probabilistic skill introduced by SPP and SPPT are mainly located in the ***,the vast majority of the reliability improvements(including increases in ensemble spread and reductions in outliers)are statistically significant,and a smaller proportion of the improvements in probabilistic skill(i.e.,decreases in continuously ranked probability score)reach statistical *** with SPPT,SPP generally has more beneficial impacts on200-hPa and 2-m temperature,along with 925-hPa and 2-m specific humidity,during the whole 15-day forecast *** other examined variables,such as 850-hPa zonal wind,850-hPa temperature,and

关键词： model uncertainty global ensemble forecast stochastic physics parameter perturbation perturbation structure

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Minimal two-spheres with constant curvature in the quaternionic projective space

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Science China Mathematics 2020年第5期63卷 993-1006页

作者： Jie fei Chiakuei peng Xiaowei Xu Department of Mathematical Sciences Xi’an Jiaotong-Liverpool UniversitySuzhou 215123China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Mathematics University of Science and Technology of ChinaHefei 230026China Wu Wen-Tsun Key Laboratory of Mathematics University of Science and Technology of ChinaChinese Academy of SciencesHefei 230026China

In this paper we completely classify the homogeneous two-spheres,especially,the minimal homogeneous ones in the quaternionic projective space *** to our classification,more minimal constant curved two-spheres in HPnare obtained than what Ohnita conjectured in the paper"Homogeneous harmonic maps into complex projective *** J Math,1990,13:87–116".

关键词： minimal two-sphere Gauss curvature quaternionic projective space

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On the Factors Influencing the High Stretch-Flangeability of a Low-Density 1180 MPa Fe-Mn-Al-C-Nbδ-QP Steel

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1291-1300页

作者： Dan‑Dan Cui peng Chen peng‑fei Wang Xiao‑Wu Li Department of Materials Physics and Chemistry School of Materials Science and Engineeringand Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education)Northeastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

Low-densityδ-quenching and partitioning(δ-QP)steels with excellent strength and ductility have been recently ***,there are still rare reports on the formability of δ-QP steels,which are critical for satisfying the manufacture of structural parts during the application in automotive *** the present work,an 1180 MPa Fe–Mn–Al–C–Nbδ-QP steel with a high ductility was adopted for the stretch–flangeability ***δ-QP steel was developed by separated quenching and partitioning processes.A good hole expansion ratio(HER)of 34.9±0.9%was obtained in the quenched steel,but it has been further increased to 52.2%by the tempering *** improved stretch–flangeability was attributed to the enhanced austenite stability and deformation *** the one hand,the stability of austenite was increased by carbon partitioning during tempering,which reduced crack possibility via the suppression of the fresh martensite *** the other hand,the tempering treatment released the internal stress caused by martensitic transformation and reduced the difference in strength among different phases,resulting in an increase in the resistance to crack initiation and propagation.

关键词： Hole expansion ratio Low-densityδ-quenching and partitioning(δ-QP)steel Stretch-flangeability Austenite stability Deformation uniformity

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Exergy analysis of operation process of district heating systems

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Journal of Central South University 2017年第7期24卷 1663-1670页

作者： JIE peng-fei KONG Xiang-fei LI Jing School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China School of Energy and Environmental Engineering Hebei University of TechnologyTianjin 300401China China Environmental Resources Technology Co. LtdBeijing 100012China

The nature of the exergy consumption of district heating(DH) systems can not be explained clearly using the first law of *** analysis method was used.A case study based on a DH system in Inner Mongolia,China,was carried *** impact of operating parameters and design parameters on the energy quality of circulating water and exergy losses of DH systems during heat distribution was *** show that the energy quality of circulating water and exergy losses of DH systems during heat distribution could be reduced by decreasing the indoor temperature or increasing radiator *** with other factors,the outdoor temperature and indoor temperature have a greater impact on the energy quality of circulating water,exergy losses of circulating water,and total exergy losses during heat *** the outdoor temperature varied by 10.00%,the average variation rates of such parameters were 85.12%,90.02%,and 64.60%,*** the outdoor temperature was 273.00 K and indoor temperature varied by 50.00%,the average variation rates of such parameters were 83.88%,99.34% and 32.87%,*** can be observed that the energy quality and exergy losses of DH systems can be reduced in the operation process.

关键词： energy quality coefficient exergy loss rate design parameters operating parameters energy conservation measures

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Studies on a Novel Characteristic Atom-pair Holographic Code Applied to Quantitative Structure-chromatographic Retention Relationship of Organic Compounds

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Chinese Journal of Structural Chemistry 2006年第11期25卷 1337-1342页

作者： ZHOU peng TIAN fei-fei WANG Jiao-Na LI Zhi-Liang College of Chemistry and Chemical Engineering Chongqing University Chongqing 400044 China State Key Laboratory of Chemo/Biosensing and Chemometrics Changsha 410012 China

6 Atomic fragment types of organic compound have been defined, and the multilevel atom-pair frequency matrix has been constructed according to the occurrence number in pairs of atomic fragments with different bond lengths in the molecule. On the basis of them, a novel molecular coding technique： characteristic atom-pair holographic code （CAHC）, is obtained. To some extent, this method exhibits a large number of benefits at the same time. For example, it can calculate 2D molecular topological descriptor easily, operate without difficulty and possess definite physicochemical meaning of 3D molecular structural characterization methods, and may fetch the complicated information of molecule, etc. Therefore, it is appropriate for the study on quantitative structure-property/activity relationship （QSPR/QSAR） of medicines and biological molecules. We attempt in this paper to utilize the method of CAHC to the quantitative prediction of reversed-phase liquid chromatogram （RPLC） retention data of 33 purine derivatives and 24 steroids. The fitting multiple correlation coefficient R2, cross-validated multiple correlation coefficient Q2 and predicted ability Q^2 pred over test set＇s samples of obtained partial least-square （PLS） regression model are respectively 0.990, 0.893 and 0.977, 0.897, 0.941.

关键词： characteristic atom-pair holographic code quantitative structure-chromatographic retention relationship characterization of molecular structure partial least-square regression

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Staging liver fibrosis with various diffusion-weighted magnetic resonance imaging models

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World Journal of Gastroenterology 2024年第9期30卷 1164-1176页

作者： Yan-Li jiang Juan Li peng-fei Zhang Feng-Xian Fan Jie Zou Pin Yang peng-fei Wang Shao-Yu Wang Jing Zhang Department of Magnetic Resonance Imaging The Second Hospital&Clinical Medical SchoolLanzhou UniversityLanzhou 730030Gansu ProvinceChina Second Clinical School Lanzhou UniversityLanzhou 730030Gansu ProvinceChina Gansu Province Clinical Research Center for Functional and Molecular Imaging The Second Hospital&Clinical Medical SchoolLanzhou UniversityLanzhou 730030Gansu ProvinceChina Department of Hepatology The Second Hospital&Clinical Medical SchoolLanzhou UniversityLanzhou 730030Gansu ProvinceChina MR Scientific Marketing Siemens HealthineersXi’an 710065Shaanxi ProvinceChina

BACKGROUND Diffusion-weighted imaging(DWI)has been developed to stage liver ***,its diagnostic performance is inconsistent among ***,it is worth studying the diagnostic value of various diffusion models for liver fibrosis in one *** To evaluate the clinical potential of six diffusion-weighted models in liver fibrosis staging and compare their diagnostic *** This prospective study enrolled 59 patients suspected of liver disease and scheduled for liver biopsy and 17 healthy *** participants underwent multi-b value *** main DWI-derived parameters included Mono-apparent diffusion coefficient(ADC)from mono-exponential DWI,intravoxel incoherent motion model-derived true diffusion coefficient(IVIM-D),diffusion kurtosis imaging-derived apparent diffusivity(DKI-MD),stretched exponential model-derived distributed diffusion coefficient(SEM-DDC),fractional order calculus(FROC)model-derived diffusion coefficient(FROC-D)and FROC model-derived microstructural quantity(FROC-μ),and continuous-time random-walk(CTRW)model-derived anomalous diffusion coefficient(CTRW-D)and CTRW model-derived temporal diffusion heterogeneity index(CTRW-α).The correlations between DWI-derived parameters and fibrosis stages and the parameters’diagnostic efficacy in detecting significant fibrosis(SF)were assessed and *** CTRW-D(r=-0.356),CTRW-α(r=-0.297),DKI-MD(r=-0.297),FROC-D(r=-0.350),FROC-μ(r=-0.321),IVIM-D(r=-0.251),Mono-ADC(r=-0.362),and SEM-DDC(r=-0.263)were significantly correlated with fibrosis *** areas under the ROC curves(AUCs)of the combined index of the six models for distinguishing SF(0.697-0.747)were higher than each of the parameters alone(0.524-0.719).The DWI models’ability to detect SF was *** combined index of CTRW model parameters had the highest AUC(0.747).CONCLUSION The DWI models were similarly valuable in distinguishing SF in patients with liver *** combined index of CTRW paramet

关键词： Liver fibrosis Magnetic resonance imaging Diffusion-weighted magnetic resonance Liver biopsy Significant fibrosis

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Synthesis and Optical Properties of Hyperbranched PAEKs Containing Porphyrin and Its Metal Derivatives

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Chinese Journal of Polymer Science 2014年第1期32卷 73-83页

作者： Xu jiang Yin-long Du Chuan Liu peng-fei Huo Zhi Geng Shu-ling Zhang 王贵宾 College of Chemistry Engineering Research Center of High Performance Plastics Ministry of Education Jilin University

Novel functional hyperbranched poly（aryl ether ketone）s （HPAEKs） bonded with nonlinear optical chromophores （meso-tetrakis（4-hydroxyphenyl） porphyrin, THPP and its metal derivatives） were synthesized and characterized by IH-NMR and UV-Vis absorption spectra. The incorporation of chromophores into HPAEKs endowed HPAEKs novel NLO and OL properties. Indeed, dendritic architecture allowed for maximum dispersion of the chromophores, avoided aggregation, more optical limiting property was obtained. Simultaneously, they retained the excellent properties of the materials, particularly in thermal stability. Their optical properties were evaluated by nonlinear optical analyses and optical limiting. The results showed that these polymers possessed good optical limiting （OL） property and large nonlinear optical （NLO） susceptibilities （ca. 10-12 esu）. All polymers containing chromophores presented excellent thermal stability （DT5 〉 524.17 ℃）.

关键词： Porphyrin Poly(aryl ether ketone)s Hyperbranched Optical limiting.

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Molecular surface functionalization of In_(2)O_(3) to tune interfacial microenvironment for enhanced catalytic performance of CO_(2) electroreduction

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Nano Research 2024年第3期17卷 1242-1250页

作者： Suwen WangQiang GaoCui Xu Shuai jiang Mengyang Zhang Xianjun Yin Hui-Qing peng Bin Liu Yu-fei Song State Key Laboratory of Chemical Resource Engineering Beijing Advanced Innovation Center for Soft Matter Science and EngineeringCollege of ChemistryBeijing University of Chemical TechnologyBeijing 100029China

Indium-based materials(e.g.,In_(2)O_(3))are a class of promising non-noble metal-based catalysts for electroreduction of carbon dioxide(CO_(2)).However,competitive hydrogen reduction reaction(HER)on indium-based catalysts hampers CO_(2) reduction reaction(CO_(2)RR)*** herein tune the interfacial microenvironment of In_(2)O_(3) through chemical graft of alkyl phosphoric acid molecules using a facile solution-processed strategy for the first time,which is distinguished from other researches that tailor intrinsic activity of In_(2)O_(3) *** surface functionalization of alkyl phosphoric acids over In_(2)O_(3) is demonstrated to remarkably boost CO_(2) *** example,octadecylphosphonic acid modified In_(2)O_(3) exhibits Faraday efficiency for H_(2) H_(2) H_(2)(FE)of as low as 6.6%and FEHCOOH of 86.5%at-0.67 V ***,which are far superior to parent In_(2)O_(3) counterparts(FE of 24.0%and FEHCOOH of 63.1%).Moreover,the enhancing effect of alkyl phosphoric acid functionalization is found to be closely related to the length of alkyl *** virtue of comprehensive experimental characterizations and molecular dynamics simulations,it is revealed that the modification of alkyl phosphoric acids significantly alters the interface microenvironment of the electrocatalyst,which changes the electrocatalyst surface from hydrophilic and aerophobic to hydrophobic and *** this case,the water molecules are pushed away and more CO_(2) molecules are trapped,increasing local CO_(2) concentration at In_(2)O_(3) active sites,thus leading to the significantly enhanced CO_(2)RR and suppressed *** work highlights the importance of regulating the interfacial microenvironment of inorganic catalysts by molecular surface functionalization as a means for promoting the electrochemical performance in electrosynthesis and beyond.

关键词： carbon dioxide(CO_(2))electroreduction interfacial microenvironment molecular surface functionalization In_(2)O_(3)catalyst water and CO_(2)diffusion

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Numerical Study on Scale Effect of Form Factor for DTMB5415, KCS,KVLCC2, and 4000TEU Container Ship

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China Ocean Engineering 2021年第5期35卷 767-778页

作者： WANG Zhan-zhi MIN Shao-song peng fei Department of Naval Architecture and Ocean Engineering Naval University of EngineeringWuhan 430033China

Four ships,a twin-propeller naval ship,two single-propeller container ships,and a single-propeller very large crude carrier(VLCC),were studied to investigate the scale effect of the form *** viscous flow fields of the ships at different scales were solved numerically via the Reynolds-averaged Navier–Stokes method combined with the shear stress transport k–ωturbulence *** numerical method was validated through comparisons with experimental data,and numerical uncertainty analysis was carried out based on the ITTC recommended *** this basis,scale effects of the form factor were analyzed using different friction lines,and scale effects of flow fields and the mean axial wake fractions were further analyzed in *** results showed that the form factor exhibited scale effects when adopting the ITTC-1957 line,and it increased with the increase in the Reynolds *** scale effect of the form factor reduces the prediction precision of the full-scale ship *** friction line has a significant effect on the form *** form factor exhibits little dependence on the Reynolds number when using the numerical friction line or the Katsui line,which is useful for full-scale ship resistance *** the increasing Reynolds number,the boundary layer thickness becomes thinner and the axial velocity contour contracts toward the center plane,and there is nearly a linear relationship between the reciprocal of mean axial wake fraction on propeller disc and Reynolds number in logarithmic scale for the three types of ship forms.

关键词： form factor scale effect ITTC-1957 line numerical calculation flow field

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Theoretical analysis on elastic buckling of nanobeams based on stress-driven nonlocal integral model

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Applied Mathematics and Mechanics(English Edition) 2020年第2期41卷 207-232页

作者： peng jiang Hai QING Cunfa GAO State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Several studies indicate that Eringen's nonlocal model may lead to some inconsistencies for both Euler-Bernoulli and Timoshenko beams, such as cantilever beams subjected to an end point force and fixed-fixed beams subjected a uniform distributed load. In this paper, the elastic buckling behavior of nanobeams, including both EulerBernoulli and Timoshenko beams, is investigated on the basis of a stress-driven nonlocal integral model. The constitutive equations are the Fredholm-type integral equations of the first kind, which can be transformed to the Volterra integral equations of the first kind. With the application of the Laplace transformation, the general solutions of the deflections and bending moments for the Euler-Bernoulli and Timoshenko beams as well as the rotation and shear force for the Timoshenko beams are obtained explicitly with several unknown constants. Considering the boundary conditions and extra constitutive constraints, the characteristic equations are obtained explicitly for the Euler-Bernoulli and Timoshenko beams under different boundary conditions, from which one can determine the critical buckling loads of nanobeams. The effects of the nonlocal parameters and buckling order on the buckling loads of nanobeams are studied numerically, and a consistent toughening effect is obtained.

关键词： Laplace transformation Volterra integral equation Fredholm integral equation stress-driven nonlocal integral model

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