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The law of strength damage and deterioration of jointed sandstone after dry-wet cycles

Journal of Mountain Science 2023年第4期20卷 1170-1182页

作者： WANG gui-lin ZHANG Tian-yu ZHANG liang School of Civil Engineering Chongqing UniversityChongqing400045China National and Local Joint Engineering Research Center for Environmental Geological Hazard Prevention and Control in the Reservoir Area Chongqing400045China School of Architecture and Civil Engineering Xi’an University of Science and TechnologyXi’an710054China

Under the periodic rise and fall of the water level in the Three Gorges Reservoir in China,the rock mass in the ebb and flow zone of the slope is always in a state of a dry-wet *** order to explore the influence of dry-wet cycle on mechanical properties of jointed sandstone,the triaxial and uniaxial compression tests of dry-wet cycle of jointed sandstone were carried *** the experiment,four groups of samples with different numbers of joints were set up,and the jointed rock samples were subjected to 20 dry-wet *** both the triaxial compression test and the Mohr-Coulomb(M-C)rock fracture criterion,the strength envelope of the sandstone samples was fitted,and their strength degradation was further analyzed and *** results show that:(1)The peak intensity and elastic modulus of the sandstone samples decrease with increased number of dry-wet cycles.(2)The total deterioration of mechanical properties of intact rock samples is bigger than that of jointed sandstone samples as the number of dry-wet cycles increases.(3)With the increase of confining pressure,the peak intensity of intact sandstone samples increases much more than that of jointed sandstone samples,which indicates that joints and their numbers have obvious influence.(4)Joints and their numbers play an important role in guiding the damage effects of sandstone samples,which weaken the damage caused by dry-wet ***,the envelope of the M-C strength criterion of intact sandstone samples moves more than that of jointed sandstone samples.

关键词： Jointed sandstone Dry-wet cycle Triaxial compression Strength damage Deterioration mechanism

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Spatiotemporal Characteristics of Typical Ecosystem Services and Their Spatial Responses to Driving Factors in Ecologically Fragile Areas in Upper Yellow River,China

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Chinese Geographical Science 2024年第4期34卷 674-688页

作者： liang gui FANG Fengman LIN Yuesheng ZHANG Zhiming School of Geography and Tourism Anhui Normal UniversityWuhu 241003China Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze Huaihe River Basin Anhui Normal UniversityWuhu 241003China

The identification of dominant driving factors for different ecosystem services(ESs)is crucial for ecological conservation and sustainable ***,the spatial heterogeneity of the dominant driving factors affecting various ESs has not been adequately elucidated,particularly in ecologically fragile *** study employed the integrated valuation of ESs and trade-offs(InVEST)model to evaluate four ESs,namely,water yield(WY),soil conservation(SC),habitat quality(HQ),and carbon storage(CS),and then to identify the dominant driving factors of spatiotemporal differentiation of ES and further to characterize the spatial heterogeneity characteristics of the dominant driving factors in the eco-fragile areas of the upper Yellow River,China from 2000 to *** results demonstrated that WY exhibited northeast-high and northwest-low patterns in the upper Yellow River region,while high values of SC and CS were distributed in central forested areas and a high value of HQ was distributed in vast grassland *** CS,WY,and SC exhibited decreasing trends over *** most critical factors affecting WY,SC,HQ,and CS were the actual evapotranspiration,precipitation,slope,and normalized difference vegetation index,*** addition,the effects of different factors on various ESs exhibited spatial *** results could provide spatial decision support for eco-protection and rehabilitation in ecologically fragile areas.

关键词： integrated valuation of ecosystem services and trade-offs(InVEST)model geographically weighted regression(GWR) natural factor spatial heterogeneity Lanxi urban agglomeration upper Yellow River China

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A first-principles study on electronic structures and elastic properties of metal dopedα-Fe(N)high nitrogen steel

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Journal of Iron and Steel Research International 2017年第1期24卷 103-110页

作者： Ji-chun Yang Xiang-jun Liu gui-xiao Jia xiao-yang Fu School of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou 014010Inner MongoliaChina

The binding energies,electronic structures and elastic properties of Ti,V,Cr,Mn,Co,Ni and Mg dopedα-Fe（N）systems have been investigated using a first-principles *** calculated results show that the dopings of Ti,V,Cr and Co improve the stability ofα-Fe（N）,and the stability ofα-Fe（N）is slightly weakened by Mn and Ni,and the doping of Mg is *** Ti,V,Cr and Mn dopedα-Fe（N）systems in which the doping metals are on the left side of Fe in the element periodic table andα-Fe（N）systems doped by Co and Ni on the right side of Fe,their corresponding cohesive forces decrease with decreasing atomic radius of the doping *** obvious interaction exists among M3 d,Fe4s3p3d and N2 *** these doping systems,metal atoms lose electrons,while N gains *** of Ti,V,Cr and Mn inα-Fe（N）strengthen the interaction between N and the surrounding metals,and it is not apparent for the dopings of Co,Ni and *** calculations of Fe15 MN systems show that,except for the Fe15 MgN system,shear modulus G and Young modulus E of Fe15 MN systems are improved,and the bulk modulus Bslightly decreases,namely,total elastic properties are *** magnitude change rule of E reflecting the cohesive force between atoms is consistent with that for the binding energies.

关键词： First principle High nitrogen steel Metal nitride Electronic structure Elastic property

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Removing mixed noise in low rank textures by convex optimization

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Computational Visual Media 2016年第3期2卷 267-276页

作者： xiao liang Institute for Advanced Study Tsinghua University

This paper introduces a new low rank texture image denoising algorithm, which can restore low rank texture contaminated by both Gaussian and salt-and-pepper noise. The algorithm formulates texture image denoising in terms of solving a low rank matrix optimization problem. Simply assuming low rank is insufficient to describe the properties of natural images, causing high noise amplitudes which lead to unsatisfactory denoising results or serious loss of image details. Thus, in addition to the low rank assumption,the continuity of natural images is also assumed by the algorithm, by adding a total variation regularizer to the optimization objective function. We further give an effective algorithm to solve this optimization problem. By combining the low rank and continuity assumptions, the proposed algorithm overcomes the deficiencies of using either the low rank assumption or total variation regularization alone. Experiments show that our algorithm can effectively remove mixed noise in low rank texture images, and is better than existing algorithms in both its subjective visual effects and in terms of quantitative objective measures.

关键词： image denoising low rank texture total variation convex optimization augmented Lagrangian method

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ITERATIVE METHODS FOR THE FORWARD-BACKWARD HEAT EQUATION

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Journal of Computational Mathematics 2005年第4期23卷 419-424页

作者： xiao-liang Cheng Jie Sun Department of Mathematics Zhejiang University Hangzhou 310028 China Department of Mathematics Zhejiang University of Finance and Economics Hangzhou 310012 China

In this paper we propose the finite difference method for the forward-backward heat equation. We use a coarse-mesh second-order central difference scheme at the middle line mesh points and derive the error estimate. Then we discuss the iterative method based on the domain decomposition for our scheme and derive the bounds for the rates of convergence. Finally we present some numerical experiments to support our analysis.

关键词： Forward-backward heat equation Finite difference method Iterative method Coarse mesh

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Verification and validation of detonation modeling

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Defence Technology（防务技术） 2019年第3期15卷 398-408页

作者： xiao liang Rui-li Wang Institute of Applied Physics and Computational Mathematics Beijing 100094 China College of Mathematics and Information Science Shandong University of Science and Technology Qingdao 266590 China

The mathematical model used to describe the detonation multi-physics phenomenon is usually given by highly coupled nonlinear partial differential equations. Numerical simulation and the computer aided engineering (CAE) technique has become the third pillar of detonation research, along with theory and experiment, due to the detonation phenomenon is difficult to explain by the theoretical analysis, and the cost required to accredit the reliability of detonation products is very high, even some physical experiments of detonation are impossible. The numerical simulation technique can solve these complex problems in the real situation repeatedly and reduce the design cost and time stunningly. But the reliability of numerical simulation software and the serviceability of the computational result seriously hinders the extension, application and the self-restoration of the simulation software, restricts its independently innovational ability. This article deals with the physical modeling, numerical simulation, and software development of detonation in a unified way. Verification and validation and uncertainty quantification (V&V&UQ) is an important approach in ensuring the credibility of the modeling and simulation of detonation. V&V of detonation is based on our independently developed detonation multiphysics software-LAD2D. We propose the verification method based on mathematical theory and program function as well as availability of its program execution. Validation is executed by comparing with the experiment data. At last, we propose the future prospect of numerical simulation software and the CAE technique, and we also pay attention to the research direction of V&V&UQ.

关键词： Verification and validation Detonation Equation of state Detonation diffraction Reaction rate law

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Influence of multi-stage heat treatment on the microstructure and mechanical properties of TC21 titanium alloy

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International Journal of Minerals,Metallurgy and Materials 2021年第2期28卷 296-304页

作者： Wei Long Song Zhang Yi-long liang Mei-gui Ou College of Materials and Metallurgy Guizhou UniversityGuiyang 550025China Key Laboratory for Materials Structure and Strength of guizhou province Guizhou UniversityGuiyang 550025China National Local Joint Engineering Laboratory for High Performance Metal Structure Materials and Manufacturing Technology Guizhou UniversityGuiyang 550025China

Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in theα+βregion(940°C)with furnace cooling(FC),air cooling(AC),and water cooling(WC),followed by a second-stage solution treatment at a lower temperature in theα+βregion(900°C),and then finally aged at 590°*** effects of the morphology and quantity ofαphases on the structure and properties of the TC21 alloy after the different heat treatments were *** in-situ tensile deformation process and crack propagation behavior were observed using scanning electron microscopy(SEM).The quantity of equiaxedαphases as well as the thickness of lamellarαphases reduced,the tensile strength increased firstly and then decreased,the elongation decreased with the increasing cooling rate after the first-stage solution *** amount and size of lamellarαphases increased after the second-stage solution treatment because of sufficient diffusion of the alloying elements,thereby leading to increased tensile *** amount of dispersedαphases increased after the third-stage aging treatment owing to the increase in the nucleation rate,resulting in a noteworthy strengthening *** the third-stage aging treatment,the first-stage FC sample exhibited better mechanical properties because it contained more equiaxedαandβtrans phases than the first-stage AC and WC samples.

关键词： multi-stage heat treatment titanium alloy in-situ tension microstructure mechanical properties

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Theoretical Study on the Ordered Structure in Lanthanum-Modified Lead Zirconate Titanate

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Chinese Physics Letters 1996年第9期13卷 696-699页

作者： gui Hong ZHANG xiao-wen GU Bing-lin Department of Materials Science and Engineering Department of Physics Tsinghua UniversityBeijing 100084

The 1/2{111}-type ordered structure observed in lanthanum-modified lead zirconate titanate has been proved to be stable in the next-nearest-neighbor approximation by the eightpoint cluster variation *** order parameter as a function of the composition of La3+and lead vacancies and the order-disorder phase diagram have been obtained.

关键词： method lanthanum Modified

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Synthesis and Crystal Structure of a Zinc(II) Complex Salt with the Schiff Base of Picolinaldehyde N-oxide and Semicarbazone

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Chinese Journal of Structural Chemistry 2005年第11期24卷 1271-1275页

作者： YU Qing ZHU Li-Gang BIAN He-Dong DENG Ji-Hua YANG xiao-E GUO gui-Quan liang Hong College of Chemistry and Chemical Engineering Guangxi Normal University Guilin Guangxi 541004 China

The title zinc（Ⅱ） complex salt [Zn（H2O）6]（ClO4）2-（PNOS）4, where PNOS is derived from picolinaldehyde N-oxide with semicarbazone, has been prepared and structurally characterized by X-ray single-crystal analysis. It crystallizes in triclinic, space group PI with a = 7.529（3）, b = 10.206（4）, c = 14.678（6）A, a = 86.293（6）, β= 87.686（7）, γ= 81.382（6）°, C28H44Cl2N16O22Zn, Mr = 1093.06, V = 1112.3（8） ,A^3 Z = 1, Dc = 1.632 g/cm^3, S = 1.089, μ（MoKa） = 0.773 mm^-1, F（000） = 564, the final R = 0.0438 and wR = 0.1076 for 3888 independent reflections with Rint = 0.0224. The crystal structure possesses a [Zn（H2O）6]^2＋ cation, two ClO4^- anions and four PNOSs. In the crystal structure, Zn^2＋ cation is located at the symcenter and coordinated by six water molecules. In [Zn（H2O）6]^2＋, an elongate octahedral complex cation, the average Zn-O bond length is 2.087（2） A. There exist a lot of H bonds in the structure, linking the cation [Zn（H2O）6]^2＋, anion ClO4^- and PNOS to form a 3D network.

关键词： zinc(Ⅱ) complex salt picolinaldehyde N-oxide semicarbazone crystal structure,Schiff base

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The α-comparison Property and Finite Nuclear Dimension of Generalized Inductive Limits for C~*-algebras

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Acta Mathematica Sinica,English Series 2018年第9期34卷 1417-1428页

作者： Yue liang liang xiao Chun FANG School of Science North University of China Taiyuan 030051 P. R. China Department of Mathematics Tongji University Shanghai 200092 P. R. China

The paper is devoted to the study of generalized inductive limit of C＊-algebras with coherent maps being completely positive contractions of order zero： the nuclear dimension of generalized inductive limit of C＊-algebras with finite nuclear dimension is finite; the generalized inductive limits of C＊-algebras with the α-comparison property also have the s-comparison property.

关键词： Finite nuclear dimension α-comparison property generalized inductive limit of C*-algebras

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