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Differential operators for Siegel-Jacobi forms

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Science China Mathematics 2016年第6期59卷 1029-1050页

作者： yang jiong YIN LinSheng Department of Mathematical Sciences Tsinghua University

For any positive integers n and m, H_(n,m):= H_n× C^(m,n) is called the Siegel-Jacobi space, with the Jacobi group acting on it. The Jacobi forms are defined on this space. We compute the Chern connection of the Siegel-Jacobi space and use it to obtain derivations of Jacobi forms. Using these results, we construct a series of invariant differential operators for Siegel-Jacobi forms. Also two kinds of Maass-Shimura type differential operators for H_(n,m) are obtained.

关键词： connection Jacobi form differential operator

Thermoelectric Transport Properties of R_yFe_3NiSb_(12)(R=Ba,Nd and Yb)

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Journal of Materials Science & Technology 2014年第11期30卷 1134-1140页

作者： Ruiheng Liu Jung Young Cho jiong yang Wenqing Zhang Lidong Chen CAS Key Laboratory for Energy-conversion Materials Shanghai Institute of CeramicsChinese Academy of Sciences Materials and Processes Laboratory GM R&D CenterWarrenMI 48090USA Department of Materials Science & Engineering University of Washington

To evaluate the influence of Ni substitution on electrical transport properties, the thermoelectric transport properties of the p-type skutterudites RyFe3NiSb12 （R = Ba, Nd and Yb） are systematically investigated from 2.5 K to 800 K. By carefully modifying the filling fractions of the three fillers, Ba, Nd and Yb, the carrier concentration is precisely adjusted, which changes proportionally to the nominal value calculated by valence counting rule. The carrier concentration dependences of mobility and Seebeck coefficient represent two band contribution in the valence band, and the optimized carrier concentration for thermoelectric performance is between （5-9） × 10^20 cm^-3. The lattice thermal conductivity of samples filled with rare-earth elements （Nd and Yb） are significantly lower as compared to Ba-filled, due to the lower resonant frequency and partial filling. Compared with Co substitution, Ni substitution tends to close the band gap, which results in heavier bipolar diffusion at high temperature for RyFe3NiSb12. However, due to state, when the carrier concentrations are similar, RyFe3NiSb12 possess higher thermal power and thus higher power factor than RyFe2Co2Sb12 in the lower temperature range. A ZT value of 0.73 is obtained for Yb0.77Fe3NiSb12 at 660 K.

关键词： Thermoelectric Skutterudites Band structure Bipolar diffusion

Smoothing Parametric Design of Addendum Surfaces for Sheet Metal Forming

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 75-82页

作者： Jixing Li Tao Ning Ping Xi Bifu Hu Tian Wang jiong yang School of Mechanical Engineering and Automation Beihang UniversityBeijing 100192China School of Mechanical Engineering Zhengzhou UniversityZhengzhou 450001China

The manual design of addendum surfaces on common CAD platforms is very tedious which requires many trialscorrections,which will certainly a ect the construction e ciency and quality of addendum surfaces,and then a ect the formability and quality of the workpiece in the process of sheet *** this paper,an automatic procedure based on parametric design method is proposed for the rapid construction of the addendum *** kernel of the parametric method is constructing boundary curves based on the shape of surfaces of workpiece and designing guide curves based on Hermite curve *** some simple parameters,the shape of the addendum surfaces could be controlled and adjusted *** addition,a minimum energy optimization method is employed to further optimize the constructed addendum surface.A finite element analysis for the sheet forming process is performed to evaluate the forming quality of constructed addendum *** instance illustrates that the addendum surface constructed by the proposed method could ensure both the overall smoothing of surfaces and the final forming quality,and it has a good e ect on springback after *** research proposes a smoothing parametric design method for addendum surfaces construction which could construct and optimize addendum surfaces rapidly.

关键词： CAD/CAM Parametric design Curve optimization Addendum surface Sheet forming

Hybrid integration method for highly maneuvering radar target detection based on a Markov motion model

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Chinese Journal of Aeronautics 2020年第6期33卷 1717-1730页

作者： Yingxiao ZHAO Zengping CHEN Yue ZHANG Jie CHEN jiong yang Yunsheng XIONG National Key L aboratory of Science and Technology on ATR National University of Defense TechnologyChangsha 410073China School of Electronic and Communication Engineering Sun Yat-sen UniversityShenzhen 518107China

To detect highly maneuvering radar targets in low signal-to-noise ratio conditions, a hybrid long-time integration method is proposed, which combines Radon-Fourier Transform(RFT), Dynamic Programming(DP), and Binary Integration(BI), named RFT-DP-BI. A Markov model with unified range-velocity quantification is formulated to describe the maneuvering target’s motion. Based on this model, long-time hybrid integration is performed. Firstly, the whole integration time is divided into multiple time segments and coherent integration is performed in each segment via RFT. Secondly, non-coherent integration is performed in all segments via DP. Thirdly, 2/4 binary integration is performed to further improve the detection performance. Finally, the detection results are exported together with target range and velocity trajectories. The proposed method can perform the long-time integration of highly maneuvering targets with arbitrary forms of ***, it has a low computational cost that is linear to the integration time. Both simulated and real radar data demonstrate that it offers good detection and estimation performances.

关键词： Binary integration Dynamic programming Long-time integration Maneuvering targets Markov motion model Radar target detection Radon-Fourier transform

Novel 3D local feature descriptor of point clouds based on spatial voxel homogenization for feature matching

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Visual Computing for Industry,Biomedicine,and Art 2023年第1期6卷 257-278页

作者： jiong yang Jian Zhang Zhengyang Cai Dongyang Fang School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhouHenan 450001China School of Management Hefei University of TechnologyHefeiAnhui 230009China

Obtaining a 3D feature description with high descriptiveness and robustness under complicated nuisances is a significant and challenging task in 3D feature *** paper proposes a novel feature description consisting of a stable local reference frame(LRF)and a feature descriptor based on local spatial ***,an improved LRF was designed by incorporating distance weights into Z-and X-axis ***,based on the LRF and voxel segmentation,a feature descriptor based on voxel homogenization was ***,uniform segmentation of cube voxels was performed,considering the eigenvalues of each voxel and its neighboring voxels,thereby enhancing the stability of the *** performance of the descriptor was strictly tested and evaluated on three public datasets,which exhibited high descriptiveness,robustness,and superior performance compared with other current ***,the descriptor was applied to a 3D registration trial,and the results demonstrated the reliability of our approach.

关键词： Local feature descriptor Voxel Local reference frame Feature extraction

Intrinsic defect study on ternary ABX2 diamond-like thermoelectric materials and analysis of the density of energy function

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Journal of Materiomics 2021年第1期7卷 19-24页

作者： Ying Zhou Xin Li Lili Xi jiong yang Materials Genome Institute Shanghai UniversityShanghai200444China

The complex intrinsic defects of four ternary diamond-like ABX2(A:Cu/Ag;B:In;X:Te/Se)compounds are studied by first-principles *** results show that Cu-based compounds are likely to generate acceptor VA defect with p-type,while Ag-based compounds form donor BA with *** reasons are analyzed by the newly introduced density of energy(DOE).

关键词： Defect Thermoelectric materials Density of energy

High-throughput screening of room temperature active Peltier cooling materials in Heusler compounds

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npj Computational Materials 2022年第1期8卷 1899-1904页

作者： Huifang Luo Xin Li Yuxiang Wang Yeqing Jin Mingjia Yao jiong yang Materials Genome Institute Shanghai UniversityShanghai200444China State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai200050China Zhejiang Laboratory HangzhouZhejiang311100China

Active Peltier cooling enables Peltier heat transfer in addition to the traditional Fourier thermal conductance,which is useful in some special applications,such as the *** the material wise,however,the study on the active Peltier cooling materials is *** carried out a high-throughput workflow to screen out 5 room-temperature active Peltier cooling materials,GaSbLi_(2),HgPbCa_(2),SnTiRu_(2),GeYbLi_(2),and GeTiFe_(2),from 2958 Heusler *** the five materials are semimetals or very narrow band gap systems with high electrical *** of these materials have relatively large Seebeck coefficients due to the band *** effective thermal conductivityκ_(eff)s,which are the summation of active Peltier thermal conductivity and passive thermal conductivity,are all greater than Cu at the room temperature andΔT=1 *** present work gives a possible way to search active cooling Peltier materials for the applications of precise temperature control.

关键词： conductivity precise Seebeck

Active learning for the power factor prediction in diamond-like thermoelectric materials

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npj Computational Materials 2020年第1期6卷 254-260页

作者： Sheng Yasong Wu jiong yang Wencong Lu Pierre Villars Wenqing Zhang Materials Genome Institute Shanghai University200444 ShanghaiChina Qianweichang College Shanghai University200444 ShanghaiChina Department of Chemistry College of ScienceShanghai University200444 ShanghaiChina Material Phases Data System CH-6354 VitznauSwitzerland Department of Physics and Shenzhen Institute for Quantum Science&Technology Southern University of Science and Technology518055 ShenzhenGuangdongChina Guangdong Provincial Key Lab for Computational Science and Material Design and Shenzhen Municipal Key Lab for Advanced Quantum Material and DeviceSouthern University of Science and Technology518055 ShenzhenGuangdongChina

The Materials Genome Initiative requires the crossing of material calculations,machine learning,and experiments to accelerate the material development *** recent years,data-based methods have been applied to the thermoelectric field,mostly on the transport *** this work,we combined data-driven machine learning and first-principles automated calculations into an active learning loop,in order to predict the p-type power factors(PFs)of diamond-like pnictides and *** active learning loop contains two procedures(1)based on a high-throughput theoretical database,machine learning methods are employed to select potential candidates and(2)computational verification is applied to these candidates about their transport *** verification data will be added into the database to improve the extrapolation abilities of the machine learning *** strategies of selecting candidates have been tested,finally the Gradient Boosting Regression model of Query by Committee strategy has the highest extrapolation accuracy(the Pearson R=0.95 on untrained systems).Based on the prediction from the machine learning models,binary pnictides,vacancy,and small atom-containing chalcogenides are predicted to have large *** bonding analysis reveals that the alterations of anionic bonding networks due to small atoms are beneficial to the PFs in these compounds.

关键词： learning bonding prediction

Intrinsic defects and the influences on electrical transport properties in quaternary diamond-like compounds:Cd_(2)Cu_(3)In_(3)Te_(8)as an example

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Journal of Materiomics 2022年第6期8卷 1222-1229页

作者： Jianxin Zhang Zhou Zhang Lili Xi Jinyang Xi jiong yang Materials Genome Institute Shanghai UniversityShanghai200444China Zhejiang Laboratory HangzhouZhejiang311100China

Over the years,the fact that the quaternary diamond-like thermoelectric materials show much lower carrier mobilities than ternary compounds remains *** this work,by adopting first-principles defect chemistry and electrical transport calculations,the fundamental origin of the difference on carrier mobility between quaternary and ternary diamond-like compounds is addressed,exemplified by Cd_(2)Cu_(3)In_(3)Te_(8).The results of defect chemistry show that the main intrinsic defects in quaternary compound Cd_(2)Cu_(3)In_(3)Te_(8) are substitutional defects,i.e.,CdIn and CdCu,differing from the copper vacancy defect in ternary Cu-based compound such as CuInTe_(2).The low defect formation energies in Cd_(2)Cu_(3)In_(3)Te_(8) result in high defect concentrations,which is caused by the similar atomic radii and electronegativities between CdeIn and *** calculations show that the low-energy defects are mainly located around the valence band maximum in Cd_(2)Cu_(3)In_(3)Te_(8).The electrical transport calculations,considering both the acoustic phonon scattering and ionized impurity scattering,demonstrate that mainly due to the higher concentration of the ionized defects,the mobility of the quaternary Cd_(2)Cu_(3)In_(3)Te_(8) is much lower than that of ternary *** work sheds light on the intrinsic defects in quaternary diamond-like compounds and their influence on charge transport.

关键词： Intrinsic defect Quaternary diamond-like compound Mobility Ionized impurity scattering