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Investigation of the Laser Powder Bed Fusion Process of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy

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Chinese Journal of Mechanical Engineering 2023年第2期36卷 78-90页

作者： Changchun zhang Tingting Liu Wenhe Liao Huiliang Wei ling zhang School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Mechanical and Vehicle Engineering West Anhui UniversityLuan 237012China

Laser powder bed fusion(LPBF)is an advanced manufacturing technology;however,inappropriate LPBF process parameters may cause printing defects in *** the present work,the LPBF process of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy was investigated by a two-step optimization ***,heat transfer and liquid flow behaviors during LPBF were simulated by a well-tested phenomenological model,and the defect formation mechanisms in the as-fabricated alloy were *** optimized process parameters for LPBF were detected as laser power changed from 195 W to 210 W,with scanning speed of 1250 mm/*** LPBF process was divided into a laser irradiation stage,a spreading flow stage,and a solidification *** morphologies and defects of deposited tracks were affected by liquid flow behavior caused by rapid cooling *** findings of this research can provide valuable support for printing defect-free metal components.

关键词： Laser powder bed fusion Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy Process parameters Heat transfer and liquid flow Defects

Privacy-Preserving Frank-Wolfe on Shuffle Model

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Acta Mathematicae Applicatae Sinica 2024年第4期40卷 887-907页

作者： ling-jie zhang Shi-song WU Hai zhang School of Mathematics Northwest UniversityXi’an 710127China School of Mathematics and Information Science Baoji University of Arts and SciencesBaoji 721013China China Southern Power Grid Artificial Intelligence Technology Company Limited Guangzhou 510700China

In this paper,we design the differentially private variants of the classical Frank-Wolfe algorithm with shuffle model in the optimization of machine *** weak assumptions and the generalized linear loss(GLL)structure,we propose a noisy Frank-Wolfe with shuffle model algorithm(NoisyFWS)and a noisy variance-reduced Frank-Wolfe with the shuffle model algorithm(NoisyVRFWS)by adding calibrated laplace noise under shuffling scheme in thel_(p)(p∈[1,2])-case,and study their privacy as well as utility guarantees for the H?lder smoothness *** particular,the privacy guarantees are mainly achieved by using advanced composition and privacy amplification by *** utility bounds of the Noisy FWS and NoisyVRFWS are analyzed and obtained the optimal excess population risksO(n-(1+α/4α+log(d)√log(1/δ)/n∈and O(n-1+α/4α+log(d)√log1(+δ)/n^(2)∈with gradient complexity O(n(1+α)^(2)/4α^(2)forα∈[1/√3,1].It turns out that the risk rates under shuffling scheme are a nearly-dimension independent rate,which is consistent with the previous work in some *** addition,there is a vital tradeoff between(α,L)-Holder smoothness GLL and the gradient *** linear gradient complexity O(n)is showed by the parameterα=1.

关键词： differential privacy Frank-Wolfe algorithm privacy amplification shuffle model

Therapeutic strategies for the costimulatory molecule OX40 in T-cell-mediated immunity

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Acta Pharmaceutica Sinica B 2020年第3期10卷 414-433页

作者： Yu Fu Qing Lin Zhirong zhang ling zhang Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial TechnologyCollege of Polymer Science and EngineeringWest China School of PharmacySichuan UniversityChengdu 610064China Department of Pharmacology Yale University School of MedicineNew HavenCT 06510USA

The T cell co-stimulatory molecule OX40 and its cognate ligand OX40 L have attracted broad research interest as a therapeutic target in T cell-mediated *** preclinical evidence highlights the therapeutic efficacy of both agonist and blockade of the OX40-OX40 L *** this progress,many questions about the immuno-modulator roles of OX40 on T cell function remain *** this review we summarize the impact of the OX40-OX40 L interaction on T cell subsets,including Th1,Th2,Th9,Th17,Th22,Treg,Tfh,and CD8+T cells,to gain a comprehensive understanding of anti-OX40 mAb-based *** potential therapeutic application of the OX40-OX40 L interaction in autoimmunity diseases and cancer immunotherapy are further discussed;OX40-OX40 L blockade may ameliorate autoantigen-specific T cell responses and reduce immune activity in autoimmunity *** also explore the rationale of targeting OX40-OX40 L interactions in cancer *** of OX40 with targeted agonist anti-OX40 mAbs conveys activating signals to T *** combined with other therapeutic treatments,such as anti-PD-1 or anti-CTLA-4 blockade,cytokines,chemotherapy,or radiotherapy,the anti-tumor activity of agonist anti-OX40 treatment will be further *** data collectively suggest great potential for OX40-mediated therapies.

关键词： OX40 CD4^+ CD8^+ Treg Autoimmunity diseases Cancer immunotherapy

Conformal Vector Fields on Finsler Warped Product Manifolds

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Acta Mathematica Sinica,English Series 2023年第8期39卷 1624-1634页

作者： Xiao ling zhang Ya Lu FENG College of Mathematics and Systems Science Xinjiang UniversityUrumqi 830046P.R.China

In this paper,we study the conformal vector fields on Finsler warped product *** obtain a system of equivalent equations that the conformal vector fields on Finsler warped product manifolds satisfy and completely char... 详细信息

关键词： Finsler warped product manifold conformal vector field homothetic vector field Killing vector field

Multi-dimensional Classification via Selective Feature Augmentation

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Machine Intelligence Research 2022年第1期19卷 38-51页

作者： Bin-Bin Jia Min-ling zhang School of Computer Science and Engineering Southeast UniversityNanjing 210096China College of Electrical and Information Engineering Lanzhou University of TechnologyLanzhou 730050China Key Laboratory of Computer Network and Information Integration Southeast UniversityMinistry of EducationChina

In multi-dimensional classification(MDC), the semantics of objects are characterized by multiple class spaces from different dimensions. Most MDC approaches try to explicitly model the dependencies among class spaces in output space. In contrast, the recently proposed feature augmentation strategy, which aims at manipulating feature space, has also been shown to be an effective solution for MDC. However, existing feature augmentation approaches only focus on designing holistic augmented features to be appended with the original features, while better generalization performance could be achieved by exploiting multiple kinds of augmented *** this paper, we propose the selective feature augmentation strategy that focuses on synergizing multiple kinds of augmented ***, by assuming that only part of the augmented features is pertinent and useful for each dimension′s model induction, we derive a classification model which can fully utilize the original features while conduct feature selection for the augmented features. To validate the effectiveness of the proposed strategy, we generate three kinds of simple augmented features based on standard k NN, weighted k NN, and maximum margin techniques, respectively. Comparative studies show that the proposed strategy achieves superior performance against both state-of-the-art MDC approaches and its degenerated versions with either kind of augmented features.

关键词： Machine learning multi-dimensional classification feature augmentation feature selection class dependencies

Local Dependence Test Between Random Vectors Based on the Robust Conditional Spearman's ρ and Kendall's τ

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Acta Mathematicae Applicatae Sinica 2023年第3期39卷 491-510页

作者： ling-yue zhang Heng-jian CUI School of Mathematical Sciences Capital Normal UniversityBeijing 100048China

This paper introduces two local conditional dependence matrices based on Spearman'sρand Kendall'sτgiven the condition that the underlying random variables belong to the intervals determined by their *** robustness is studied by means of the influence functions of conditional Spearman'sρand Kendall'sτ.Using the two matrices,we construct the corresponding test statistics of local conditional dependence and derive their limit behavior including consistency,null and alternative asymptotic *** studies illustrate a superior power performance of the proposed Kendall-based *** data analysis with proposed methods provides a precise description and explanation of some financial phenomena in terms of mathematical statistics.

关键词： local dependence influence function rank correlation U-statistic

Flame retardant synergy between interfacial and bulk carbonation in glass fiber reinforced polypropylene

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Chinese Journal of Chemical Engineering 2020年第6期28卷 1725-1732页

作者： Yuan Xue Rongjing Zhao ling zhang Chunzhong Li Shanghai Engineering Research Center of Hierarchical Nanomaterials Key Laboratory for Ultrafine Materials of Ministry of EducationSchool of Materials Science and EngineeringEast China University of Science&TechnologyShanghai 200237China

Glass fiber reinforced polypropylene(GF-PP)composites have high flammability on account of wick effect which leads to accelerated flow of the polymer melt along the glass fibers(GF)surface to the flame *** this study,dipentaerythritol(DPER),a charring agent,was adsorbed on the GF surface through the hydrogen bond between silane coupling agent and *** has a synergistic effect with the intumescent flame retardants(IFR)added in the composites,which can induce interfacial carbonization on the surface of GF,thus transforming the intrinsic smooth GF surface into roughness *** this way,the negative effect of the wick effect in flame retardancy is ***,the char residues remained on the surface of GF can bring an improved adhesion between GF and char residues formed in the resin so that a more stable barrier char layer is *** PP composites with 20 wt%modified glass fiber(M-GF)and 30 wt%IFR can achieve the UL-94 V-0,and its limiting oxygen index(LOI)value increased from 16.5%to 29.5%.Simultaneously,the heat release rate(HRR),total heat release(THR)and total smoke release(TSR)decreased significantly,and the peak of heat release rate(PHRR)reduced60.6%compared with GF-PP.

关键词： Glass fiber Wick effect Flame retardant Interfacial Char layers

On the texture memory effect of a cross-rolled Mg-2Zn-2Gd plate after unidirectional rolling

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Journal of Materials Science & Technology 2020年第6期41卷 98-104页

作者： Pengfei zhang Yunchang Xin ling zhang Shiwei Pan Qing Liu International Joint Laboratory for Light Alloys College of Materials Science and EngineeringChongqing UniversityChongqing400030China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing400044China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing100083China

A Mg-2Zn-2Gd alloy subjected to a cross rolling and annealing often has a texture with c-axes of grains evenly distributing on a circle approximately 40°away from the normal direction(ND),which can completely remove the planar mechanical *** texture memory effect and planar mechanical anisotropy of such a cross-rolled plate after an unidirectional rolling and subsequent annealing were systematically *** results show that the circle-shaped texture is partially retained after the unidirectional rolling and annealing,with basal poles evenly distributing on an ellipse approximately 30°–40°away from the *** small texture difference will lead to quite different mechanical anisotropies between the two plates,namely,a quite low anisotropy of yield strength between the rolling direction(RD)and transverse direction(TD)before the unidirectional rolling,in contrast to an obvious mechanical anisotropy after unidirectional rolling.A quantitative calculation shows that tension along the RD of the plate after the unidirectional rolling will activate a much higher fraction of prismatic slip than tension along the *** much higher critical resolved shear stress for prismatic slip than that for basal slip or{10■2}twinning accounts for the much higher yield strength of TD tension than that of *** mechanisms for texture evolution during the unidirectional rolling and annealing were also discussed.

关键词： Magnesium alloys Rolling Texture Mechanical anisotropy

Staged reaction kinetics and characteristics of iron oxide direct reduction by carbon

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International Journal of Minerals,Metallurgy and Materials 2015年第10期22卷 1025-1032页

作者： Ru-fei Wei Da-qiang Cang ling-ling zhang Yuan-yuan Bai School of Metallurgical and Ecological Engineering University of Science and Technology Beijing State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Civil and Environmental Engineering University of Science and Technology Beijing Key Laboratory of Electromagnetic Processing of Materials of the Ministry of Education Northeastern University

Staged reduction kinetics and characteristics of iron oxide direct reduction by carbon were studied in this work. The characteristics were investigated by simultaneous thermogravimetric analysis, X-ray diffraction（XRD）, and quadrupole mass spectrometry. The kinetics parameters of the reduction stages were obtained by isoconversional（model-free） methods. Three stages in the reduction are Fe2O3→Fe3O4, Fe3O4→Fe O, and Fe O→Fe, which start at 912 K, 1255 K, and 1397 K, respectively. The CO content in the evolved gas is lower than the CO2content in the Fe2O3→Fe3O4stage but is substantially greater than the CO2 contents in the Fe3O4→Fe O and Fe O→Fe stages, where gasification starts at approximately 1205 K. The activation energy（E） of the three stages are 126–309 k J/mol, 628 k J/mol, and 648 k J/mol, respectively. The restrictive step of the total reduction is Fe O→Fe. If the rate of the total reduction is to be improved, the rate of the Fe O→Fe reduction should be improved first. The activation energy of the first stage is much lower than those of the latter two stages because of carbon gasification. Carbon gasification and FexOy reduction by CO, which are the restrictive step in the last two stages, require further study.

关键词： iron oxides direct reduction reduction kinetics re