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Crustal deformation and dynamics of Early Cretaceous in the North China Craton

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Science China Earth Sciences 2021年第9期64卷 1428-1450页

作者： Guang ZHU Yuanchao LU Nan SU Xiaodong WU Hao YIN Shuai ZHANG Chenglong XIE Manlan NIU School of Resource and Environmental Engineering Hefei University of TechnologyHefei230009China

The Early Cretaceous represents a peak period of the North China Craton(NCC)destruction.A comprehensive analysis of crustal deformation during this period can reveal processes and dynamics of the *** peak destruction of the NCC was associated with intense extension whose representative deformation products are metamorphic core complexes(MCCs),extensional domes and rifted *** MCCs occurred along both northern and southern margins of the NCC,and resulted from synchronous extension and magmatism,showing difference from the typical orogen-type MCCs in many *** MCCs of the Early Cretaceous were replaced by extensional domes under relatively weak extension and *** contrast to a major depression-type basin of the Early Cretaceous in the western NCC,rifted basins of the same age in the eastern NCC appeared as medium-to small-scale ones *** the eastern NCC,the rifted basins north of the Bohai Bay are characterized by a feature similar to an active rift whereas those south of the Bohai present similarity to a passive *** sorts of extensional structures developed during the peak destruction indicate a stable stress state of NE-SE extension over the entire central to eastern NCC,consistent with the plate margin-driven stress *** distribution of the extensional structures presents an 1800 km wide back-arc extension region in the central to eastern NCC,consistent with the Paleo-Pacific slab rollback model following flat ***-spatial variation of initial extension and volcanic activity during the peak period also supports the rollback model right after the flat oceanic *** crustal deformation evolution demonstrates that the peak destruction of the NCC took place after the B-episode compression of the Yanshan Movement of the earliest Early Cretaceous and terminated with onset of the C-episode compression of the earliest Late Cretaceous.

关键词： Peak period of craton destruction Metamorphic core complex Extensional domes Rifted basins Dynamic setting

Effects of Sm Co-doping on Luminescent Properties of Sr4Al14O25:M (M=Mn4+, Cr3+) Phosphors

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Chinese Journal of Chemical Physics 2015年第6期28卷 -页

作者： Yu-dong Xu Xu-dong Peng Lei Wang Min Shi Yuan Zhang Quan Wang San Qi School of Materials Science and Engineering Hefei University of Technology Hefei 230009 China

The Sr4Al14O25:M and doped Sr4Al14O25:M+Sm3+ (M=Mn4+, Cr3+) phosphors were synthesized by a solid-state reaction method and their luminescent properties were investigated. The results showed that the co-doping of Sm ions did not change the positions of excitation band and emission band but significantly improved the luminescent properties of Sr4Al14O25:Cr3+phosphors; whereas, the emission intensity of Sr4Al14O25:Mn4+ was reduced remarkably when Sm ions were co-doped. In addtion, a radiative-form energy transfer from Sm3+ to Cr3+ was observed for the first time in the Cr, Sm co-doped Sr4Al14O25phosphors. The results indicated that Sm ions could significantly improve the emission intensity of Sr4Al14O25:Cr3+, making the Sm3+co-doped Sr4Al14O25:Cr3+phosphor a promising candidate for the applications in display and solid state lightening.

关键词： Phosphor Co-doping Strontium aluminates Energy transfer

Efficient Solution to Electromagnetic Scattering Problems of Bodies of Revolution by Compressive Sensing

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Chinese Physics Letters 2016年第1期33卷 136-139页

作者：孔勐陈明生张量曹欣远吴先良 School of Electronic and Information Engineering Anhui University Hefei 230601 School of Electronic and Information Engineering Hefei Normal University Hefei 230601

Under the theory structure of compressive sensing （CS）, an underdetermined equation is deduced for describing the discrete solution of the electromagnetic integral equation of body of revolution （BOR）, which will result in a small-scale impedance matrix. In the new linear equation system, the small-scale impedance matrix can be regarded as the measurement matrix in CS, while the excited vector is the measurement of unknown currents. Instead of solving dense full rank matrix equations by the iterative method, with suitable sparse representation, for unknown currents on the surface of BOR, the entire current can be accurately obtained by reconstructed algorithms in CS for small-scale undetermined equations. Numerical results show that the proposed method can greatly improve the computgtional efficiency and can decrease memory consumed.

关键词： of in is on by BOR Efficient Solution to Electromagnetic Scattering Problems of Bodies of Revolution by Compressive Sensing

Compound fabrication technology of semi-solid billet of Al-Si alloy based on SIMA method

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中国有色金属学会会刊：英文版 2006年第A03期16卷 1224-1231页

作者：薛克敏弭光宝王清瑞 School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China

Based on SIMA, the Al-Si alloy semi-solid billets were successfully fabricated by means of strain inducement and isothermal treatment for AlSi9Mg poured in the range of near-liquidus. Through orthogonal test, the effects of combination action of near-liquidus casting, strain inducement and isothermal treatment on the morphology of primaryα-Al phase of AlSi9Mg close to eutectic point were investigated, and the optimal match relation between the processing parameters of solidification, deformation parameters of strain inducement, processing parameters of isothermal treatment and microstructure parameters of semi-solid alloy was established. The results indicate that compared with the single near-liquidus casting or SIMA, the microstructure of primaryα-Al phase in AlSi9Mg alloy prepared by compound fabrication process is more homogeneous, with more globular and finer particles, which has average grain size of 40-50 urn and shape factor of greater than 0.75. After holding at 605℃for 30-40 min under a certain cooling rate, increased deformation volume in SIMA benefits the refinement of the grain and the improvement of the morphology for primary phase.

关键词：铝硅合金复合工艺等温处理有色金属

Effect of La_(2)Sn_(2)O_(7)content on Ag-La_(2)Sn_(2)O_(7)/SnO_(2)arc erosion behavior and mechanism

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Journal of Rare Earths 2022年第9期40卷 1488-1498,I0006页

作者： Mengli Cao Yi Feng Lili Wang Ting Zhao Hao Zhao Zijue Zhou School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China

La_(2)Sn_(2)O_(7)/SnO_(2)powder was synthesized by chemical co-precipitation method,and Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites were prepared by hot-pressing *** electrical resistivity,density,Brinell hardness and flexural strength of Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites were ***,the effect of La_(2)Sn_(2)O_(7)content on the arc erosion behavior of Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites at 7 kV voltage was *** the increase of La_(2)Sn_(2)O_(7)content,the arc duration and arc energy decrease,and the breakdown strength *** surface morphology of Ag-La_(2)Sn_(2)O_(2)/SnO_(2)composites after arc erosion was investigated using scanning electron microscopy and three-dimensio nal laser confocal scanning *** the increase of La_(2)Sn_(2)O_(7)content,the smaller the erosion damage,the better the anti-arc erosion ***,too much La_(2)Sn_(2)O_(7)results in the decrease of Ag-La_(2)Sn_(2)O_(7)/SnO_(2)properties and severe arc erosion.X-ray photoelectron spectroscopy was used to determine the composition of the erosion *** effect of La_(2)Sn_(2)O_(7)on wettability between Ag and SnO_(2)was investigated,and the erosion mechanism of Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites was discussed *** study can provide a reference for the application of Ag matrix electrical contact materials in high-voltage electrical appliances.

关键词： Ag-La_(2)Sn_(2)O_(7)/SnO_(2)composites Arc erosion behavior Erosion mechanism Rare earths

Delay-dependent H_(2)/H_(∞) Control for Vehicle Magneto-rheological Semi-active Suspension

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Chinese Journal of Mechanical Engineering 2011年第6期24卷 1028-1034页

作者： CHEN Wuwei ZHU Maofei School of Mechanical and Automotive Engineering Hefei University of TechnologyHefei 230009China

The exist researches of the magneto-rheological semi-active suspension(MSAS) control mainly focus on the design of control laws,which aim at obtaining an optimal control strategy to improve the ride comfort and handling *** the controller design,the stability of the MSAS system cannot be confirmed owing to the control input time delay considered *** this paper,a quarter vehicle MSAS model with time-delay is ***,through formulating the sprung mass acceleration suitably as the optimization object,suspension deflection and tyre dynamic load and coulomb damping force as the constraint objects,with considering the control input time-delay,a delay-dependent state feedback H2/H∞ controller is *** to Lyapunov-Krasovskii functional theory,the sufficient conditions for asymptotic stability and the existence of delay-dependent H2/H∞ controller are obtained,and the controller design is transformed into the minimization problem for linear function through linear matrix inequality(LMI).Random road excitation simulations and experiments are carried *** simulation and experiment results show that the design can preserve the closed-loop stability and achieve the performances for MSAS system in spite of the existence of the control input *** present study can provide an important basis and method for research on time-delay problem in MSAS and other chassis subsystems.

关键词： magneto-rheological semi-active suspension(MSAS) time-delay, delay-dependent H2/H∞ state feedback control linear matrix inequality(LMI)

An Ensemble Tree Classifier for Highly Imbalanced Data Classification

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Journal of Systems Science & Complexity 2021年第6期34卷 2250-2266页

作者： SHI Peibei WANG Zhong School of Computer Science and Technology Hefei Normal UniversityHefei 230601China

The performance of traditional imbalanced classification algorithms is degraded when dealing with highly imbalanced *** to deal with highly imbalanced data is a difficult *** this paper,the authors propose an ensemble tree classifier for highly imbalanced data *** ensemble tree classifier is constructed with a complete binary tree structure.A mathematical model is established based on the features and classification performance of the classifier,and it is proven that the model parameters of the ensemble classifier can be solved by ***,the AdaBoost method is used as the benchmark classifier to construct the tree structure ***,the classification cost of the model is calculated,and the quantitative mathematical description between the cost and features of the ensemble tree classifier model is ***,the cost of the classification model is transformed into an optimization problem,and the parameters of the integrated tree classifier are given through theoretical *** approach is tested on several highly imbalanced datasets in different fields and takes the AUC(area under the curve)and F-measure as evaluation *** with the traditional imbalanced classification algorithm,the ensemble tree classifier has better classification performance.

关键词： Ensemble learning F-measure imbalanced classification mathematical model

BLOCK BASED NEWTON-LIKE BLENDING INTERPOLATION

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Journal of Computational Mathematics 2006年第4期24卷 515-526页

作者： Qian-jin Zhao Jie-qing Tan School of Computer and Information Hefei University of Technology Hefei 230009 China Department of Mathematics and Physics Anhui University of Science and Technology Huainan 232001 China Institute of Applied Mathematics Hefei University of Technology Hefei 230009 China

Newton＇s polynomial interpolation may be the favourite linear interpolation in the sense that it is built up by means of the divided differences which can be calculated recursively and produce useful intermediate results. However Newton interpolation is in fact point based interpolation since a new interpolating polynomial with one more degree is obtained by adding a new support point into the current set of support points once at a time. In this paper we extend the point based interpolation to the block based interpolation. Inspired by the idea of the modern architectural design, we first divide the original set of support points into some subsets （blocks）, then construct each block by using whatever interpolation means, linear or rational and finally assemble these blocks by Newton＇s method to shape the whole interpolation scheme. Clearly our method offers many flexible interpolation schemes for choices which include the classical Newton＇s polynomial interpolation as its special case. A bivariate analogy is also discussed and numerical examples are given to show the effectiveness of our method.

关键词： Interpolation Block based divided differences Blending method.

Tailoring strength and ductility of high-entropy CrMnFeCoNi alloy by adding Al

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Rare Metals 2022年第3期41卷 1015-1021页

作者： Xin Xian Zhi-Hong Zhong Li-Jing Lin Zhi-Xiong Zhu Chang Chen Yu-Cheng Wu School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China

High-entropy alloys with high strength and acceptable ductility at both room and elevated temperatures for high-temperature structural applications are desired. In this paper, CrMnFeCoNi alloy with outstanding ductility but low strength was selected as baseline alloy to study the formation of hard phase to strengthen this ductile alloy by adding Al into it. The results indicate that there is a phase structure transition from fcc to bcc when adding enough Al into CrMnFeCoNi. The yield strength and hardness increase with the content of Al increasing, due to the formation of hard bcc phase in the ductile CrMnFeCoNi *** CrMnFeCoNiAl alloy with a bcc structure shows a high yield strength and adequate ductility at elevated temperatures. At 400 and 500℃, the yield strength and ductility of CrMnFeCoNiAl alloy are 975.59 MPa and6.39%and 989.48 MPa and 9.15%, respectively. An example of tailoring the strength and ductility of high-entropy alloy is demonstrated in this paper.

关键词： High-entropy alloys Structure transition Strength Ductility