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Renormalization group theory for temperature-driven first-order phase transitions in scalar models

Frontiers of physics 2017年第6期12卷 79-96页

作者： ning liang Fan Zhong State Key Laboratory of Optoelectronic Materials and Technologies School of Physics Sun Yat-sen University Guangzhou 510275 China

We study the scaling and universal behavior of temperature-driven first-order phase transitions in scalar models. These transitions are found to exhibit rich phenomena, though they are controlled by a single complex-conjugate pair of imaginary fixed points of φ3 theory. Scaling theories and renormalization group theories are developed to account for the phenomena, and three universality classes with their own hysteresis exponents are found： a field-like thermal class, a partly thermal class, and a purely thermal class, designated, respectively, as Thermal Classes I, II, and III. The first two classes arise from the opposite limits of the scaling forms proposed and may cross over to each other depending on the temperature sweep rate. They are both described by a massless model and a purely massive model, both of which are equivalent and are derived from φ3 theory via symmetry. Thermal Class III characterizes the cooling transitions in the absence of applied external fields and is described by purely thermal models, which include cases in which the order parameters possess different symmetries and thus exhibit different universality classes. For the purely thermal models whose free energies contain odd-symmetry terms, Thermal Class III emerges only at the mean-field level and is identical to Thermal Class II. Fluctuations change the model into the other two models. Using the extant three- and two- loop results for the static and dynamic exponents for the Yang-Lee edge singularity, respectively, which falls into the same universality class as φ3 theory, we estimate the thermal hysteresis exponents of the various classes to the same precision. Comparisons with numerical results and experiments are briefly discussed.

关键词： first-order phase transitions thermal phase transitions renormalization group theory φ3theory scaling and universality thermal classes instability exponents finite-time scaling scalar model,dynamics thermal hysteresis

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Extraction Fuzzy Linguistic Rules from Neural Networks for Maximizing Tool Life in High-speed Milling Process

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Chinese Journal of Mechanical Engineering 2009年第3期22卷 341-346页

作者： SHEN Zhigang HE ning LI liang College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In metal cutting industry it is a common practice to search for optimal combination of cutting parameters in order to maximize the tool life for a fixed minimum value of material removal rate（MRR）. After the advent of high-speed milling（HSM） pro cess, lots of experimental and theoretical researches have been done for this purpose which mainly emphasized on the optimization of the cutting parameters. It is highly beneficial to convert raw data into a comprehensive knowledge-based expert system using fuzzy logic as the reasoning mechanism. In this paper an attempt has been presented for the extraction of the rules from fuzzy neural network（FNN） so as to have the most effective knowledge-base for given set of data. Experiments were conducted to determine the best values of cutting speeds that can maximize tool life for different combinations of input parameters. A fuzzy neural network was constructed based on the fuzzification of input parameters and the cutting speed. After training process, raw rule sets were extracted and a rule pruning approach was proposed to obtain concise linguistic rules. The estimation process with fuzzy inference showed that the optimized combination of fuzzy rules provided the estimation error of only 6.34 m/min as compared to 314 m/min of that of randomized combination of rule s.

关键词： high-speed milling rule extraction neural network fuzzy logic

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Potentiometric sensor for sensitive and selective detection of heparin

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Chinese Chemical Letters 2012年第2期23卷 233-236页

作者： Yan Chen Rong ning liang Wei Qin CAS and Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes Yantai Institute of Coastal Zone Research Chinese Academy of Sciences Yantai 264003 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

A polymeric membrane ion-selective electrode for determination of heparin is described in this *** is incorporated into the organic membrane phase and functions as sensing element for selective recognition of *** proposed membrane electrode exhibits high selectivity for heparin over lipophilic anions such as thiocyanide and *** potentiometric response to the concentration of heparin is Unear in the range of 0.01-0.4 U/mL and a lower detection limit of 0.005 U/mL can be achieved.

关键词： Potentiometry Sensing element Heparin Protamine Polyion sensor

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A DFT/TD-DFT study of effect of different substituent on ESIPT fluorescence features of 2-(2’-hydroxyphenyl)-4-chloromethylthiazole derivatives

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Chinese Physics B 2022年第3期31卷 589-596页

作者： Shen-Yang Su Xiu-ning liang Hua Fang Department of Chemistry and Material Science College of ScienceNanjing Forestry UniversityNanjing 210037China

Based on density functional theory(DFT) and time-dependent density functional theory(TD-DFT), the effects of substituent on the excited-state intramolecular proton transfer(ESIPT) process and photophysical properties of 2-(2’-hydroxyphenyl)-4-chloromethylthiazole(HCT) are studied. The electron-donating group(CH_(3), OH) and electronwithdrawing group(CF_(3), CHO) are introduced to analyze the changes of intramolecular H-bond, the frontier molecular orbitals, the absorption/fluorescence spectra, and the energy barrier of ESIPT process. The calculation results indicate that electron-donating group strengthens the intramolecular H-bond in the S_(1) state, and leads to an easier ESIPT process. The electron-withdrawing group weakens the corresponding H-bond and makes ESIPT process a little harder. Different substituents also affect the photophysical properties of HCT. The electron-withdrawing group(CF_(3), CHO) has a little effect on electronic spectra. The electron-donating group(CH_(3), OH) red-shifts both the absorption and fluorescence emission peaks of HCT, respectively, which causes the Stokes shift to increase.

关键词： excited-state intramolecular proton transfer(ESIPT) TD-DFT substitution

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Effects of heat treatment on microstructures and properties of a heterostructured alloy with dissimilar components fabricated by WAAM

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Rare Metals 2024年第9期43卷 4441-4461页

作者： Ming-Cai Pan Jun-Qiang Xu Yong Peng ning-ning liang Si Lan Qi Zhou Ke-Hong Wang School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China Key Laboratory of Controlled Arc Intelligent Additive Manufacturing Technology Nanjing 210094China

Heat treatment significantly influences homogeneous material microstructures and mechanical properties,which can be improved by an optimal heat treatment ***,heat treatment application to heterogeneous materials presents significant challenges due to compositional and microstructural ***,a laminated heterostructured alloy comprising alternating316L stainless steel(SS)and 18Ni300 maraging steel(MS)layers fabricated using wire and arc additive manufacturing was investigated.A solution treatment was applied at900℃for 0.5 ***,the solution-treated and asfabricated(AF)samples were aged at 500℃for 4 h;these samples were denoted SA and AT,*** AT phase compositions and orientations were similar to those of *** SA 316L SS layer resembled that of AF,but the SA 18Ni300 MS layers exhibited a reduced austenite phase fraction and refined grain size,attributable to solid-state *** the AT sample,aging induced the formation of nanoscale acicularωphase and ellipsoidal Ni_(3)Ti,Fe_(2)Mo,and X precipitates in the 18Ni300 MS ***,the SA precipitates contained acicular Fe Ni_(2)and ellipsoidalω,Ni_(3)Ti,and X precipitates,and their fractions were lower than those in AT ***18Ni300 MS layer microhardness in the heat-treated samples increased due to nanoprecipitation,but the 316L SS layer microhardness resembled that of *** AT and SA ultimate tensile strengths increased to(1360±50)and(1473±41)MPa,respectively,attributable to precipitation *** SA 316L SS layer exhibited a high stress-induced martensite fraction,enhancing the ductility of heated samples.

关键词： Laminated heterostructured alloy Heat treatment Wire and arc additive manufacturing Microstructure Mechanical property

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Molecular Dynamics Simulation of Glass Transition Behavior of Polyimide Ensemble

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Chinese Chemical Letters 2001年第9期12卷 827-828页

作者： Tai ning liang Xiang Yu ZHANG Xiao Zhen YANG State Key Laboratory of Polymer Physics and Chemistry Center for Molecular ScienceInstitute of ChemistryChinese Academy of SciencesBeijing 100080 Institute of Chemistry&Engineering Heilongjian UniversityHarbin 150089

The effect of chromophores to the glass transition temperature of polyimide ensemble has been investigated by means of molecular dynamics simulation in conjunction with barrier analysis. Simulated Tg results indicated a good agreement with experimental value. This study showed the MD simulation could estimate the effect of chromophores to the Tg of polyimide ensemble conveniently and an estimation approach method had a surprising deviation of Tg from experiment. At the same time, a polyimide structure with higher barrier energy was designed and validated by MD simulation.

关键词： Glass transition temperature molecular dynamics simulation

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Elastic deformation behavior of CuZrAlNb metallic glass matrix composites with different crystallization degrees

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Journal of Iron and Steel Research International 2017年第4期24卷 430-434页

作者： Wei-zhong liang Zhi-liang ning Gang Wang Zhi-jie Kang Hai-chao Sun Yong-sheng Chen School of Materials Science and Engineering Heilongjiang University of Science and TechnologyHarbin 150022HeilongjiangChina School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001HeilongjiangChina National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001HeilongjiangChina Laboratory for Microstructures Shanghai UniversityShanghai 200444China

The room temperature brittleness has been a long standing problem in bulk metallic glasses *** has seriously limited the application potential of metallic glasses and their *** elastic deformation behaviors of metallic glass matrix composites are closely related to their plastic deformation *** elastic deformation behaviors of Cu48-xZr48Al4Nbx（x=0,3at.%）metallic glass matrix composites（MGMCs）with different crystallization degrees were investigated using an in-situ digital image correlation（DIC）technique during tensile *** decreasing crystallization degree,MGMC exhibits obvious elastic deformation ability and an increased tensile fracture *** notable tensile elasticity is attributed to the larger shear strain heterogeneity emerging on the surface of the *** finding has implications for the development of MGMCs with excellent tensile properties.

关键词： Metallic glass matrix composite Digital image correlation technique Elastic deformation Strain field

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Experimental study on seismic response and progressive failure characteristics of bedding rock slopes

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第5期14卷 1394-1405页

作者： Mingdong Zang Guoxiang Yang Jinyu Dong Shengwen Qi Jianxian He ning liang School of Engineering and Technology China University of Geosciences(Beijing)Beijing100083China Institute of Geosafety China University of Geosciences(Beijing)Beijing100083China Research Institute of Geotechnical Engineering and Hydraulic Structure North China University of Water Resources and Electric PowerZhengzhou450011China Key Laboratory of Shale Gas and Geoengineering Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing100029China University of Chinese Academy of Sciences Beijing100049China Department of Geotechnical Engineering School of Civil EngineeringSouthwest Jiaotong UniversityChengdu610031China

Bedding rock slopes are common geological features in nature that are prone to failure under strong earthquakes. Their failures induce catastrophic landslides and form barrier lakes, posing severe threats to people’s lives and property. Based on the similarity criteria, a bedding rock slope model with a length of3 m, a width of 0.8 m, and a height of 1.6 m was constructed to facilitate large-scale shaking table *** results showed that with the increase of vibration time, the natural frequency of the model slope decreased, but the damping ratio increased. Damage to the rock mass structure altered the dynamic characteristics of the slope;therefore, amplification of the acceleration was found to be nonlinear and uneven. Furthermore, the acceleration was amplified nonlinearly with the increase of slope elevation along the slope surface and the vertical section, and the maximum acceleration amplification factor(AAF) occurred at the slope crest. Before visible deformation, the AAF increased with increasing shaking intensity;however, it decreased with increasing shaking intensity after obvious deformation. The slope was likely to slide along the bedding planes at a shallow depth below the slope surface. The upper part of the slope mainly experienced a tensile-shear effect, whereas the lower part suffered a compressive-shear force. The progressive failure process of the model slope can be divided into four stages, and the dislocated rock mass can be summarized into three zones. The testing data provide a good explanation of the dynamic behavior of the rock slope when subjected to an earthquake and may serve as a helpful reference in implementing antiseismic measures for earthquake-induced landslides.

关键词： Bedding rock slope Large-scale shaking table test Seismic response Progressive failure characteristics

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Characteristics of grain size distribution and the shear strength analysis of Chenjiaba long runout coseismic landslide

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Journal of Mountain Science 2019年第9期16卷 2110-2125页

作者： GETAHUN Ephrem QI Sheng-wen GUO Song-feng ZOU Yu liang ning Key Laboratory of Shale Gas and Geoengineering Institute of Geology and Geophysics Chinese Academy of Sciences Chaoyang District Beijing 100029 China Institute of Earth Science Chinese Academy of Sciences Beijing 100029 China University of Chinese Academy of Sciences Beijing 100049 China Arba Minch University Department of Geology P. O. Box 21 Arba Minch 00251 Ethiopia

Study on the grain size distribution characteristics and the frictional strength behavior of the slide deposits are helpful to disclose the landslide runout process and understand the mechanism of a long runout landslide. We performed grain size distribution analysis on samples collected from Chenjiaba landslide induced by Wenchuan earthquake. The grain size distribution of samples from the landslide sections quantitatively depicts a gradual coarsening upward grading from shear zone to the top section. Then a multistage-multiphase ring shearing approach was used to determine a comparative shear strength behavior of samples from each landslide section. In this method, a sample was sheared continuously for large displacement and fast rate on different normal stress conditions. The multiphase shear mode with a maximum of 105 mm/min rate has allowed observing the qualitative change and patterns of the frictional resistance behaviors of soils under different normal stresses. The results of coefficient of friction values under multiphase shear mode have shown substantial post peak shear weakening behaviors after large shear displacement that can be narrated with long runout processes. The shear strength test results indicate that the shear zone samples have developed higher friction angle values compared to overlying section samples, on the last phase of shear process, which may be very important to understand the braking mechanism of a long runout landslide.

关键词： Grain size distribution Long runout Landslide Multistage-Multiphase Ring Shear

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Microstructural evolution of spray-formed Al-11.5Zn-2.0Mg-1.6Cu alloy during hot-extrusion and heat-treatment

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Transactions of Nonferrous Metals Society of China 2009年第S02期19卷 343-348页

作者： GUO Shu ning Zhi-liang CAO Fu-yang SUN Jian-fei School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Al-11.5Zn-2.0Mg-1.6Cu alloy was synthesized by spray forming(SF)technique followed by hot extrusion and *** microstructural evolution was investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM)with energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD)in the whole *** curve of hardness as a function of aging time was obtained at 120℃.Test results indicate that the grain morphology is equiaxed and uniform in the central region of the spray-formed billet,but fine and irregular in the bottom and top *** the grain boundary and the intragranular phases are identified as MgZn_(2) *** extrusion promotes the refinement of the *** boundary phase disappears,meanwhile,η-phase(MgZn_(2))and Al_(3)Zr particles precipitate from the matrix after *** alloy reaches its maximum hardness after being aged at 120℃for 14 h,associated with a massive precipitation of intermediateη′-phase (MgZn)in the matrix.

关键词： Al-Zn-Mg-Cu alloy spray forming microstructure hot extrusion aging

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