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Whole-process modeling of titanium disc forming for gradient distributions of temperature and deformation

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Chinese Journal of Aeronautics 2020年第12期33卷 3550-3563页

作者： Hongwei LI Bin CHEN Mei zhan jing HE Xinxin SUN Xin zhanG State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi'an 710072China

Gradient distributions of temperature and deformation(GDTD)are crucial for achieving dual-performance discs of titanium alloys which is required by the service environment of ***,heating,cooling and deforming sequence in the whole process of the titanium disc forming,which leads to difficulties for achieving GDTD due to a lot of *** solve this problem,a whole-process model of the titanium disc forming for GDTD has been *** the model,heating and cooling via heat radiation,conduction and convection,and deforming by local loading with mold chilling are all *** on heating and cooling as well as deforming were carried out by using a furnace and the Gleeble-3500 *** experimental data are used to determine thermal parameters and constitutive relations of the IMI834 titanium alloy,and then to verify the reliability of the *** the model was used to simulate the evolution rules of temperature and deformation of the titanium *** results show that the heating surface,furnace temperature,billet profile and loading rate play the core role for the control of GDTD,and thus a set of parameters were ***,this work provides a base for developing a new forming technology of the dual-performance titanium discs with the approach of local heating and local loading.

关键词： Gradient distributions of temperature and deformation Heat conduction Heat radiation Mold chilling Titanium disc Whole-process modelling

Soil Moisture Monitoring Based on Land Surface Temperature-Vegetation Index Space Derived from MODIS Data

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Pedosphere 2014年第4期24卷 450-460页

作者： zhanG Feng zhanG Li-wen SHI jing-jing HUANG jing-Feng Institute of Agricultural Remote Sensing and Information Technology Zhejiang University

Soil moisture has been considered as one of the main indicators that are widely used in the fields of hydrology, climate, ecology and others. The land surface temperature-vegetation index （LST-VI） space has comprehensive information of the sensor from the visible to thermal infrared band and can well reflect the regional soil moisture conditions. In this study, 9 pairs of moderate-resolution imaging spectroradiometer （MODIS） products （MOD09A1 and MODllA2）, covering 5 provinces in Southwest China, were chosen to construct the LST-VI space, and then the spatial distribution of soil moisture in 5 provinces of Southwest China was monitored by the temperature vegetation dryness index （TVDI）. Three LST-VI spaces were constructed by normalized difference vegetation index （NDVI）, enhanced vegetation index （EVI）, and modified soil-adjusted vegetation index （MSAVI）, respectively. The correlations between the soil moisture data from 98 sites and the 3 TVDIs calculated by LST-NDVI, LST-EVI and LST-MSAVI, respectively, were analyzed. The results showed that TVDI was a useful parameter for soil surface moisture conditions. The TVDI calculated from the LST-EVI space （TVDIE） revealed a better correlation with soil moisture than those calculated from the LST-NDVI and LST-MSAVI spaces. From the different stages of the TVDIE space, it is concluded that TVDIE can effectively show the temporal and spatial differences of soil moisture, and is an effective approach to monitor soil moisture condition.

关键词： enhanced vegetation index modified soil-adjusted vegetation index normalized difference vegetation index temperature vegetation dryness indices

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Mira Symbiotic Stars

Chinese Journal of Astronomy and Astrophysics 2007年第1期7卷 101-110页

作者： Guo-Liang Lu Chun-Hua Zhu zhan-wen Han National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 Department of Physics Xinjiang University Urumqi 830046

We have carried out a detailed study of Mira symbiotic stars by means of a population synthesis code. We estimate the number of Mira symbiotic stars in the Galaxy as 1700 - 3100 and the Galactic occurrence rate of Mira symbiotic novae as from -0.9 to 6.0 yr^-1, depending on the model assumptions. The distributions of the orbital periods, the masses of the components, mass-loss rates of cool components, mass-accretion rates of hot components and Mira pulsation periods in Mira symbiotic stars are simulated. By a comparison of the number ratio of Mira symbiotic stars to all symbiotic stars, we find the model with the stellar wind model of Winters et al. to be reasonable.

关键词： binaries symbiotic-Galaxy stellar content-stars Mira variables

Deep Fault Diagnosis for Rotating Machinery with Scarce Labeled Samples

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Chinese Journal of Electronics 2020年第4期29卷 693-704页

作者： zhanG jing TIAN jing wen Tao YANG Xiaohui RAO Yong XU Xiaobin School of Automation Hangzhou Dianzi University School of Electronic and Information Engineering Beijing Jiaotong University School of Mathematics and Statistics Henan University Hofon Automation Co. Ltd

Early and accurately detecting faults is crucial for the modern manufacturing *** proposed a novel Deep fault diagnosis(DFD) method for rotating machinery with scarce labeled samples.A spectrogram of the raw vibration signal is calculated by applying a Short-time Fourier transform(STFT).Several candidate Support vector machine(SVM) models are trained with different combinations of features in the feature pool with scarce labeled *** evaluating the pretrained SVM models on the validation set, the most discriminative features and best-performed SVM models can be selected, which are used to make predictions on the unlabeled *** predicted labels reserve the expert knowledge originally carried by the SVM *** are combined together with the scarce fine labeled samples to form an Augmented training set(ATS).Finally,a novel 2D deep Convolutional neural network(CNN)model is trained on the ATS to learn more discriminative features and a better *** results on two fault diagnosis datasets demonstrate the effectiveness of the proposed DFD.

关键词： Fault diagnosis Deep CNN Spectrograms Knowledge-transferring

The surviving companions in type Ia supernova remnants

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Research in Astronomy and Astrophysics 2017年第8期17卷 69-80页

作者： li-qing chen xiang-cun meng zhan-wen han yunnan observatories chinese academy of scienceskunming 650216china key laboratory for the structure and evolution of celestial objects chinese academy of scienceskunming 650216china university of chinese academy of sciences beijing 100049china center for astronomical mega-science chinese academy of sciencesbeijing 100012china

The single-degenerate(SD)model is one of the most popular progenitor models of type Ia supernovae(SNe Ia),in which the companion star can survive after an SN Ia explosion and show peculiar ***,searching for the surviving companion in type Ia supernova remnants(SNRs)is a potential method to verify the SD *** the SN 1604 remnant(Kepler’s SNR),although Chandra X-ray observation suggests that the progenitor is most likely a WD+AGB system,the surviving companion has not been *** possible reason is rapid rotation of the white dwarf(WD),causing explosion of the WD to be delayed for a spin-down timescale,and then the companion evolved into a WD before the supernova explosion,so the companion is too dim to be *** aim to verify this possible explanation by carrying out binary evolution *** this paper,we use Eggleton’s stellar evolution code to calculate the evolution of binaries consisting of a WD+red giant(RG).We assume that the rapidly rotating WD can continuously increase its mass when its mass exceeds the Chandrasekhar mass limit(MCh=1.378 M_⊙)until the mass-transfer rate decreases to be lower than a critical ***,we obtain the final masses of a WD in the range 1.378 M_⊙ to 2.707 M_⊙.We also show that if the spin-down time is less than 10~6yr,the companion star will be very bright and easily observed;but if the spin-down time is as long as^10~7 yr,the luminosities of the surviving companion would be lower than the detection *** simulation provides guidance in hunting for the surviving companion stars in SNRs,and the fact that no surviving companion has been found in Kepler’s SNR may not be definite evidence disfavoring the SD origin of Kepler’s SN.

关键词： stars evolution—binaries symbiotic—supernovae individual(SN 1604,SN 1006)

Formability enhancement in hot spinning of titanium alloy thin-walled tube via prediction and control of ductile fracture

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Chinese Journal of Aeronautics 2022年第2期35卷 320-331页

作者： Pengfei GAO Chao YU Mingwang FU Lu XING Mei zhan jing GUO State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of High-Performance Precision Forming Technology and EquipmentSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HornKowloonHong Kong 999077China Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900China

The damage and fracture in hot spinning of titanium alloy is a very complex process under the combined effects of microstructure evolution and stress *** this study,their dependences on processing parameters were investigated by an integrated FE model considering microstructure and damage evolution,and revealing the effects of microstructure and stress states on damage *** results show that the inner surface of workpiece with the largest voids volume fraction is the place with the greatest potential of *** is mainly attributed to the superposition effects of positive stress triaxiality and the smallest dynamic recrystallization(DRX)fraction andβphase fraction at the inner *** damage degree is decreased gradually with the increase of initial spinning temperature and roller fillet ***,it is first decreased and then increased with the increases of spinning pass and roller feed rate,which can be explained based on the variations ofβphase fraction,DRX fraction,stress state and tensile plastic strain with processing *** addition,the dominant influencing mechanisms were identified and ***,the thickness reduction without defect in the hot spinning of TA15 alloy tube is greatly increased by proposing an optimal processing scheme.

关键词： Control of ductile fracture Dynamic recrystallization Forming limit Hot spinning Titanium alloy tube

A Study of Binary Stellar Population Synthesis of Elliptical Galaxies

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Chinese Journal of Astronomy and Astrophysics 2006年第6期6卷 669-679页

作者： Zhong-Mu Li Feng-Hui zhang zhan-wen Han National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 Graduate School of Chinese Academy of Sciences Beijing 100049

We determined the relative stellar ages and metallicities of about 80 elliptical galaxies in both low and high density environments using the latest binary stellar population （BSP） synthesis model and tested the predictions of a recent hierarchical formation model that adopted the new ACDM cosmology. The stellar ages and metallicities were estimated from two high-quality published spectra line indices, the Hβ and [MgFe] indices. The results show that the stellar populations of elliptical galaxies are older than 3.9 Gyr and more metal rich than 0.02. Most of our results are in agreement with the model predictions; （1） elliptical galaxies in denser environment are redder and have older populations than field galaxies; （2） elliptical galaxies with more massive stellar components are redder and have older and more metal rich populations than less massive ones; （3） the most massive galaxies have the oldest and most metal rich stars. However, some of our results differ from the model predictions on the metallicity distributions of low- and high-density elliptical galaxies and the dependence on the distance to the cluster center.

关键词： galaxies stellar content- galaxies formation- galaxies elliptical and lenticular, cD

NIR Emission Nanoparticles Based on FRET Composed of AIE Luminogens and NIR Dyes for Two-photon Fluorescence Imaging

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Chinese Journal of Polymer Science 2019年第4期37卷 401-408,I0007页

作者： Lei-jing Liu wen Liu Guang Jia Zhi-Yuan Wu Bin Xu Jun Qian wen-jing Tian State Key Lab for Supramolecular Structure and Materials Jilin University State Key Laboratory of Modern Optical Instrumentations Centre for Optical and Electromagnetic ResearchJORCEP (Sino-Swedish Joint Research Center of Photonics)Zhejiang University

Near-infrared(NIR) nanoparticles(NPs) based on fluorescence resonance energy transfer(FRET) were prepared by coencapsulation of a red aggregation-induced emission(AIE) molecule, 2-(4-bromophenyl)-3-(4-(4-(diphenylamino)styryl)phenyl)fumaronitrile(TB), and a commercial NIR fluorescence dye, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide)(NIR775) with an amphiphilic polymer poly(styrene-co-maleic anhydride)(PSMA). The surface of the NPs, PSMA@TB/NIR775, was modified with poly(ethylene glycol)(PEG) to increase the in vivo biocompatibility of the NPs. The PSMA@TB/NIR775 NPs showed a strong NIR(780 nm) narrow emission and excellent two-photon absorption property. Moreover, the NPs exhibited good monodispersity, stability, and low *** the excitation of a 1040 nm femtosecond(fs) laser, the emission peaks at 680 nm of TB and 780 nm of NIR775 excited by FRET were obtained. We utilized PSMA@TB/NIR775 NPs as fluorescent contrast agents for two-photon excited NIR microscopic imaging, and good NIR imaging effect of mouse brain vasculature was obtained with the imaging depth of about 150 μm. The FRET strategy by coencapsulating AIE molecule and NIR dye will be helpful in preparing more narrow emission NIR probes for deep-tissue biological imaging.

关键词： NIR emission AIE FRET Two-photon imaging Amphiphilic polymer

α-C(sp^(3))-H Arylation of Cyclic Carbonyl Compounds

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Natural Products and Bioprospecting 2021年第4期11卷 379-404页

作者： Mei Wang Wei Wang Dashan Li wen-jing Wang Rui zhan Li-Dong Shao Yunnan Key Laboratory of Southern Medicinal Utilization School of Chinese Materia MedicaYunnan University of Chinese MedicineKunming 650050China School of Chemistry and Chemical Engineering Yunnan Normal UniversityKunming 650050China

α-C(sp^(3))-H arylation is an important type of C-H *** biologically significant natural products,chemi-cal intermediates,and drugs have been effectively prepared via C-H *** carbonyl compounds comprise of cyclic ketones,enones,lactones,and ***α-C(sp^(3))-H arylation of these compounds have been exhibited high efficiency in forming C(sp^(3))-C(sp^(2))bonds,played a crucial role in organic synthesis,and attracted majority of interests from organic and medicinal *** review focused on the most significant advances including methods,mechanism,and applications in total synthesis of natural products in the field ofα-C(sp^(3))-H arylations of cyclic carbonyl compounds in recent years.

关键词： C-H functionalization α-C(sp^(3))-H arylation Cyclic carbonyl compounds