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A novel phenomenological model using a sine function for finite-element simulation of large-strain hot deformation

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Science China(Technological Sciences) 2018年第5期61卷 748-760页

作者： zeng fan HU ChengLiang ZHAO Zhen Institute of Forming Technology & Equipment Shanghai Jiao Tong University

In hot deformation, the flow stress curves of steels always present as two typical types: at relatively high temperature and low strain rate, the flow stress may first increase and then attain a steady value without reaching an obvious peak stress; in other situations, the flow stress decreases after reaching peak stress and then attains a steady value. A new phenomenological model,described by a sine-function equation, is proposed to define the relationship between flow stress and deformation parameters. A series of isothermal compressions for a carbon steel were carried out, as a case study, to obtain basic experimental *** of the new model were sequentially determined. The predicted results of the proposed model were compared with actual measured data. Good accuracy was found in the standard statistical parameters of correlation coefficient, root mean square error, and average absolute relative error with the values of 0.935, 7.137 MPa and 4.352%, respectively. Discussion of applications of different models in finite-element simulation demonstrated the benefit of the new model. When comparing the simulation results of three different deformation patterns with large strain, the new model showed 10%–20% lower predicted forming load than the original Arrhenius equation, and better applicability and reliability than modified Arrhenius equations.

关键词： phenomenological model high temperature large strain finite-element simulation

Topological Stability and Pseudo-orbit Tracing Property for Homeomorphisms on Uniform Spaces

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Acta Mathematica Sinica,English Series 2022年第2期38卷 431-442页

作者： Ke Song YAN fan Ping zeng School of Information and Statistics Guangxi University of Finance and EconomicsNanning 530003P.R.China

In this paper,we investigate the topological stability and pseudo-orbit tracing property for homeomorphisms on uniform *** introduce the concept of topological stability for homeomorphisms on compact uniform spaces and prove that if a homeomorphism on a compact uniform space is expansive and has pseudo-orbit tracing property,then it is topologically ***,we discuss the topological stability for homeomorphisms on uniform spaces from the view of *** introduce definitions of topologically stable point and shadowable point for homeomorphisms on uniform spaces and show that every shadowable point of an expansive homeomorphism on a compact uniform space is topologically stable.

关键词： Topological stability pseudo-orbit tracing property expansiveness uniform space

Development of a novel Eu^(3+)-doped tantalate red-emitting phosphor for w-LEDs application

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Journal of Rare Earths 2024年第8期42卷 1479-1488,I0003页

作者： fan zeng Jingjing Ru Bing Zhao Feiyun Guo Jianzhong Chen College of Chemistry and Materials Fujian Province University Key Laboratory of Green Energy and Environment CatalysisNingde Normal University.Ningde352100China School of Environment and Resources School of Carbon Neutral and Modern IndustryFujian Normal UniversityFuzhou350007China College of Information and Mechanical&Electrical Engineering Ningde Normal UniversityNingde352100China College of Chemistry Fuzhou UniversityFuzhou350108China

Two novel phosphors LiBa_(4(1-x))Eu_(4x)Ta_(3)O_(12)(H-LBTO:xEu^(3+)) and Li_(0.25)Ba_(1-x)Eu_(x)Ta_(0.75)O_(3)(C-LBTO:xEu^(3+))were prepared successfully by a molten salt *** transformation between these two structures was realized by changing the sintering temperature or changing the Eu^(3+) ions concentration,which was also demonstrated by the X-ray diffraction(XRD),scanning electron microscopy(SEM),diffuse reflectance spectra(DRS),and photoluminescence excitation(PLE) analyses,Both the sintering temperature and the Eu^(3+)ions doping concentration have significant impact on the formation of the crystal *** these phosphors sintered at 1023 K exhibit two major luminescence lines at 594 and 614 nm under nearUV light of 395 nm excitation,corresponding to Eu^(3+)ions typical transitions of ^(5)D_(0)→^(7)F_(1) and ^(5)D_(0)→^(7)F_(2).The optimum concentration of Eu^(3+) ions is 9 mol% for C-LBTO:xEu^(3+) samples and the quenching interaction type is the nearest-neighbor ion *** thermal stability of the C-LBTO:0.09Eu^(3+)sample was investigated in detail and the device application further suggests that C-LBTO:0.09Eu^(3+) can be used as a red phosphor for near-UV excited w-LEDs in lighting.

关键词： Phosphor Tantalate LED device Rare earths

A Study on the Performances of Solar Air Collectors Having a Hemispherical Dimple on the Absorber Plate

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Fluid Dynamics & Materials Processing 2024年第5期20卷 939-955页

作者： Shuilian Li fan zeng Xinli Wei School of Architecture and Environmental Engineering Zhengzhou Technical CollegeZhengzhou450121China School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou450001China

In order to increase the efficiency of solar air collectors,a new variant with a protrusion is proposed in this study,and its performances are analyzed from two points of view,namely,in terms of optics and thermodynamics *** comparing and analyzing the light paths of the protrusion and the dimple,it can be concluded that when sunlight shines on the dimple,it is reflected and absorbed multiple times,whereas for the sunlight shining on the protrusion,there is no secondary reflection or absorption of *** the lighting area and the properties of the surfaces are the same,the absorption rate of the dimple is 10.3 percentage points higher than that of the *** the range of Reynolds number from 3000 to 11000,numerical simulations about the effects of the relative height(e/Dh=0.033–0.1)and relative spacing(p/e=4.5–8.5)of protrusions on air heat transfer and flow resistance show that,in terms of comprehensive evaluation coefficient(PF),the best relative height is 0.085,when the relative spacing is 5.A correlation of Nu and f with Re,e/Dh and p/e is obtained by linear regression of the results,in order to provide a useful reference for the design and optimization of this kind of solar air collector.

关键词： Heat transfer hemispherical protrusion dimple solar air collector correlation

Synthesis of polynorbornene with pendant moiety bearing azide and terminal alkyne groups

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Chinese Chemical Letters 2011年第7期22卷 785-788页

作者： Ze Zhang Zhi Wei Peng Kun zeng fan School of Biochemical Engineering Anhui Polytechnic University Wuhu 241000 China Department of Chemistry University of Science and Technology of China Hefei 230026 China

A powerful approach to the synthesis of an unprecedented polynorbornene with pendant moiety bearing azide and terminal alkyne groups is developed. Two key intermediates, namely, 3-azido-5-（2-（trimethylsilyl）ethynyl） benzyl alcohol and 4-（4-azatricyclo [5.***.1.0^2.6]dec-8-en-4-yl） benzoic acid, were optimally synthesized for convergent synthesis of the corresponding monomer.

关键词： Polynorbomene Azide Alkyne Esterification Metathesis

Critical thinking on amyloid-beta-targeted therapy:challenges and perspectives

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Science China(Life Sciences) 2021年第6期64卷 926-937页

作者： Bin-Lu Sun Yang Chen Dong-Yu fan Chi Zhu fan zeng Yan-Jiang Wang Department of Neurology and Center for Clinical Neuroscience Daping HospitalThird Military Medical UniversityChongqing 400042China Chongqing Key Laboratory of Ageing and Brain Diseases Chongqing 400042China Institute of Brain and Intelligence Third Military Medical UniversityChongqing 400042China

Amyloid-beta(Aβ)plays a pivotal role in the pathogenesis of Alzheimer's disease(AD)and has been regarded as the main therapeutic target for ***,most of the Aβ-targeted clinical trials have not ***,the Aβ-targeted therapeutic strategy on treating this complex disease needs to be *** this review,we analyzed the challenges and critical points of the current anti-Aβtherapeutic *** addition to Aβ,multiple pathological events such as tau hyperphosphorylation,oxidative stress,and neuroinflammation,which are involved in AD pathogenesis and synergistically drive disease progression,could be important targets for AD *** prevention strategies are needed for the successful management of AD due to its complex and dynamic *** perspective addressing the disease pathogenesis within and outside the brain,as well as the multidomain intervention targeting risk factors and comorbidities,are important approaches for the therapeutic solutions of AD.

关键词： Alzheimer's disease amyloidβ immunotherapy β-secretase γ-secretase enzyme inhibitor multi-target therapy tertiary prevention strategy

Effect of plastic strain and forming temperature on magnetic properties of low-carbon steel

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International Journal of Minerals,Metallurgy and Materials 2020年第2期27卷 210-219页

作者： fan zeng Xue-jiao Bai Cheng-liang Hu Min-jun Tang Zhen Zhao Institute of Forming Technology and Equipment School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200030China National Engineering Research Center of Die&Mold CAD Shanghai Jiao Tong UniversityShanghai 200030China Jiangsu Longcheng Precision Forging Co. Ltd.Changzhou 213000China

Claw poles are a key component of automobile *** output power performance of the generator is very dependent on the magnetic properties of its claw *** deformation is known to significantly change the magnetic behavior of ferromagnetic materials in claw *** this paper,changes in the magnetic properties of low-carbon steel,used for claw pole components due to their plastic deformation,were investigated for different strains and ***-shaped material samples were prepared by machining and their magnetic properties were *** surface roughness was first evaluated and a machining process with an arithmetic average of roughness Ra 1.6μm was selected as enabling the lowest measurement *** loops at different applied magnetic fields of the material were obtained for different plastic strains and forming *** magnetic parameters of magnetic flux density,coercivity,and remanence were obtained and compared with magnetic flux density as the primary *** showed that machining,cold forming,and hot forming all led to lower magnetic flux density,larger coercivity,and smaller *** flux density showed a sharp decrease at the start of plastic deformation,but as the strain increased,the decreasing trend gradually reached a constant *** decrease was much larger for cold forming than for hot *** example,at 500 A/m,the degradation of magnetic flux density with a reduction percentage of 5%at room temperature was about 50%,while that of hot forming at 1200°C was about 10%.Results of this research may provide a reference for the future process design of hot-forged claw poles.

关键词： low-carbon steel magnetic properties hot forming cold forming surface roughness

Effect of Flexible Units on the Properties of Silicon-containing Phenyleneethynylene Hybrid Oligomers

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Chinese Journal of Polymer Science 2016年第1期34卷 52-58页

作者： Xian-kai Lin Rui Wang fan zeng 李书宏徐彩虹 School of Science Beijing Technology andBusiness UniversityBeijing 100048China Institute of Chemistry Chinese'Academy of SciencesBeijing 100190China

New silicon-containing phenyleneethynylene hybrid oligomers P2, P3, and P4 were synthesized via Sonogashira cross-coupling reactions of ethynyl-terminated silazane monomer N,N′-bis（4-ethynylphenyl）-1,1-diphenylsilazane（M1） and corresponding bis-（4-bromo-phenyl）-ended organosilicon unit containing monomers, respectively. These new oligomers were easily soluble in common solvents. The incorporation of flexible organosilicon units in the oligomers leads to blue-shift in both the UV-Vis absorption and fluorescence emission spectra similarly. The results of differential scanning calorimetry（DSC） indicate that the flexible units relieve the rigidity of oligomeric chain and provide favorable conformation for thermal cross-linking reactions. The oligomers show good thermal and thermal-oxidative stability from the thermogravimetric analysis（TGA）, with their decomposition temperature at 10% weight loss（T10%） higher than 400 ？C under both nitrogen and air atmosphere.

关键词： Sonogashira cross-coupling Organosilicon unit Hybrid oligomers Thermal properties

Austenite grain growth of medium-carbon alloy steel with aluminum additions during heating process

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International Journal of Minerals,Metallurgy and Materials 2019年第3期26卷 282-290页

作者： Zi-yi Liu Yan-ping Bao Min Wang Xin Li fan-zheng zeng State key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Xiangtan Iron & Steel Co. Ltd.of Hunan Valin

In this study, the effects of heating temperature(850–1100°C) and holding time(30–150 min) on the grain growth behavior of austenite in medium-carbon alloy steel were investigated by conducting experiments. The abnormal grain growth and mixed grain structure phenomenon are explained using an equilibrium precipitation phase diagram calculated by Thermo-Calc software package. The Al N particles were observed by field-emission scanning electron microscopy(FESEM), and the amount of AlN precipitations was detected by electron probe microanalysis(EPMA). Based on the research results, it was found that the average grain size of austenite in the test steel increased continuously with the increase of temperature and holding time. Furthermore, the abnormal growth of austenite occurred in the test steel at 950°C, and the heating temperature affected the austenite grain size more significantly. In addition, the decline in the amount of AlN second-phase particle in the test steel, which weakened the "pinning" effect on austenite grain boundaries, resulted in abnormal growth and the development of mixed austenite grain structures. The prediction model for describing the austenite grain growth of medium-carbon alloy steel during heating was established by regression analysis of the experimental data, and the model was verified to be highly accurate.

关键词： alloy steel austenite grain AlN growth model