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Microstructure and cementitious properties of calcined clay-containing gangue

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International Journal of Minerals,Metallurgy and Materials 2009年第4期16卷 482-486页

作者： hua-jian li Heng-hu Sun China Academy of Railway Science Beijing 100081 China Department of Materials Science and Engineering Tsinghua University Beij ing 100084 China

To investigate the optimum calcination temperature and cementitious properties of gangue, the microstructure of clay-containing gangue calcined at different temperatures was analyzed by X-ray diffraction （XRD）, infrared spectroscopy （IR）, and magnetic angle spinning nuclear magnetic resonance （MAS NMR）. The results show that the structure of kaolinite in the gangue sample calcined at 500℃ is destroyed. The XRD spectra show the disappearance of illite at about 800℃ and the formation ofmullite at about 1000℃. With the increase in calcination temperature, octahedral （6-coordinated） aluminum is transformed to tetrahedral （4-coordinated） aluminum gradually. For the gangue sample calcined at 700℃, the 29Si MAS NMR sharp peak of Q4 （framework silicate-quartz） is left. Compared with kaolinite in gangue, the thermal transformed temperature of pure kaolinite is lagged. On the basis of the microstructure and cementitious properties of calcined gangue, the results can be concluded, in order to obtain metakaolinite, the optimum calcination temperature of this gangue is about 500℃, and the optimum temperature is about 700℃ for activated SiO2 and Al2O3.

关键词： gangue heat activation microstructure cementitious properties

SUPERCRITICAL CARBON DIOXIDE ASSISTED SYNTHESIS OF AMPHIPHIliC GRAFT COPOLYMERS BASED ON POLY(STYRENE-CO-MALEIC ANHYDRIDE) WITH METHOXYL POLY(ETHYLENE GLYCOL) SIDE CHAINS

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Chinese Journal of Polymer Science 2012年第2期30卷 173-180页

作者： jian-hua Wang li-ping Zhu Zhuan Yi jian-hua li You-yi Xu Bao-ku Zhu MOE Key Laboratory of Macromolecule Synthesis and Functionalization MOE Engineering Research Center of Membrane and Water Treatment TechnologyDepartment of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China

Supercritical carbon dioxide （scCO2） was used as a reaction medium in synthesizing amphiphilic graft copolymers composed of poly（styrene-co-maleic anhydride）（SMA） backbones and methoxyl poly（ethylene glycol）（MPEG） side chains via esterification. The synthesized copolymers were characterized by Fourier transform infrared spectroscopy （FTIR）, gel permeation chromatography （GPC）, IH-NMR, thermo-gravimetric analysis （TGA） and differential scanning calorimetric analysis （DSC）. The gelation phenomenon was suppressed effectively by tuning reaction conditions. The influences of scCO2 temperature and pressure on the conversion of anhydride were investigated. It was found that the highest conversion ratio occurred at 80~C under a constant pressure of 14 MPa or 26 MPa. With the increase of scCO2 pressure, the conversion ratio increased first, and then leveled off. The conversion ratio of anhydride could be controlled by regulating the reaction conditions. It was also revealed that using low molecular weight MPEG brought a high conversion ratio of anhydride.

关键词： Supercritical carbon dioxide Poly(styrene-co-maleic anhydride) Poly(ethylene glycol) Amphiphilic graftcopolymer.

Effect of the microstructure of Al 7050-T7451 on anodic oxide formation in sulfuric acid

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International Journal of Minerals,Metallurgy and Materials 2009年第4期16卷 432-438页

作者： jian-hua liu Ming li Song-mei li Min huang School of Materials Science and Engineering Beihang University Beijing 100083 China

The effect of the microstructure of an Al 7050-T7451 substrate on the anodic oxide formation in sulfuric acid was studied in this article. The microstructure of the substrate was assessed by optical microscope （OM） and transmission electron microscope （TEM）. The surface and cross-section morphologies of the oxide films were examined by scanning electron microscope （SEM）. The chemical composition of intermetallic particles in the alloys and films was investigated using energy dispersive spectroscope （EDS）. The roles of intermetallic phases and grain or subgrain boundaries on the oxide film formation were researched using the potentiodynamic and potentiostatic polarization technique in sulfuric acid solution. The results show that the transition of coarse intermetallic particles or grain （subgrain） boundaries at the surface of Al alloys can be characterized by potentiodynamic polarization curves. The surface and cross-section micrographs of the anodic layer seem to preserve the microstructure of the substrate. Large cavities in the anodic films are caused by the preferential dissolution of coarse AItCuMg particles and the entrance of Cu-rich remnants into the electrolyte during anodizing. The Al7Cu2Fe particles tend to be occluded in the oxide layer or lose from the oxide surface because of peripheral trenching. Small pores in the films are induced by the dissolution of precipitates in grain or subgrain boundaries. The film surface of recrystallized grain bodies is smooth and homogeneous.

关键词： aluminum alloys anodic oxide intermetallic particles grain boundaries

Characterization of the fracture compressibility and its permeability for shale under the effects of proppant embedment and compaction:A preliminary study

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Petroleum Science 2022年第3期19卷 1125-1138页

作者： jian-hua li Bo-Bo li Qiao-Yun Cheng Zheng Gao Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Institute of Deep Earth Sciences and Green EnergyCollege of Civil and Transportation EngineeringShenzhen UniversityShenzhen518060GuangdongChina Shenzhen Key Laboratory of Deep Underground Engineering Sciences and Green Energy Shenzhen UniversityShenzhen518060GuangdongChina College of Mining Guizhou UniversityGuiyang550025GuizhouChina Guizhou Key Laboratory of Comprehensive Utilization of Non-metallic Mineral Resources Guiyang550025GuizhouChina National&Local Joint Laboratory of Engineering for Effective Utilization of Regional Mineral Resources from Karst Areas Guizhou UniversityGuiyang550025GuizhouChina

Hydraulic fracturing technology plays a key role in improving the recovery rate of shale *** improvement of permeability in relation to hydraulic fracturing depends on changes brought about by the proppant on the fracture structure in *** it is of great significance to describe the microscopic changes during this process by means of an accurate theoretical *** this study,based on the heterogeneity of shale fracture and the compaction and embedment of a proppant,we proposed a permeability model to examine the combined effects of a proppant and stress to describe the change mechanism in ***,changes in fracture width and porosity were considered,and a calculation model of fracture compressibility under proppant compaction and embedment was *** difference from previous studies is that the compressibility and permeability of supported fractures can be further quantified and analyzed by this ***,its rationality was verified by publicly released test *** results show that,the compressive effect of stress and the embedding of proppant both have a negative impact on shale permeability.

关键词： Shale Fracture compressibility Permeability Hydraulic fracturing Proppant embedment

Preparation and application of efficient TiO_2 /ACFs photocatalyst

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Journal of Environmental Sciences 2006年第5期18卷 979-982页

作者： liU jian-hua YANG Rong li Song-mei School of Materials Science and Engineering Beihang University Beijing 100083 China

Activated carbon fibers （ACFs） supported titanium dioxide （TiO2） photocatalyst was developed by sol-gel method. The surface morphology and microstructure of the photocatalyst were characterized with scan electron microscope（SEM）, X-ray diffraction patterns and specific surface area analysis. The prepared photocatalyst is specially helpful for the removal of low molecular weight organic pollutants in wastewater. Decomposition efficiency of methylene blue solution by TiO2/ACFs catalyst reached almost 100% under 60 min reaction, while the decomposition efficiency by pure TiO2 was only 25% under 3 h reaction. The mineralization of toluene aqueous solution was measured by total organic carbon instrument, and the evolution of intermediate species was detected by gas chromatograph instrument. The results indicated that the prepared photocatalyst not only enhanced the photoactivity of TiO2, but also suppressed the emergence of intermediate species, which may be more deleterious to human. The enhancement of photocatalysis was due to increased efficiency of adsorption and desorption, which were control steps in heterogeneous photocatalysis.

关键词： titanium dioxide activated carbon fibers photocatalysis toluene methylene blue

Synthesis and Nonlinear Optical Property of a Series of New Chromophores Containing Furan Ring as the Only Conjugation Bridge

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Chinese Chemical Letters 2002年第10期13卷 945-948页

作者： Wei ZHANG jian li hua Jin Gui QIN Department of Chemistry Wuhan UniversityWuhan 430072

This paper reports the synthesis and the nonlinear optical property of a series of new chromophores which contain furan ring as the only conjugation bridge for the first time. They are characterized by UV-VIS, FT-IR, H-1 NMR, MS and elemental analysis. Their dipole moment and the first-order molecular hyperpolarizability (beta) are calculated and compared with those or the analogues containing either benzene or thiophene as file conjugation bridge.

关键词： 5-diethylamino-2-furaldehyde chromophores nonlinear optical materials organic synthesis the first-order molecular hyperpolarizability (b)

Numerical calculation of hydrodynamic characteristics of tidal currents for submarine excavation engineering in coastal area

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Water Science and Engineering 2016年第2期9卷 155-164页

作者： jian-hua li liang-sheng Zhu Shan-ju Zhang College of Civil and Transportation Engineering South China University of Technology

In coastal areas with complicated flow movement, deposition and scour readily occur in submarine excavation projects. In this study, a smallscale model, with a high resolution in the vertical direction, was used to simulate the tidal current around a submarine excavation project. The finite volume method was used to solve Navier-Stokes equations and the Reynolds stress transport equation, and the entire process of the tidal current was simulated with unstructured meshes, generated in the irregular shape area, and structured meshes, generated in other water *** meshes near the bottom and free surface were densified with a minimum layer thickness of 0.05 m. The volume of fluid method was used to track the free surface, the volume fraction of cells on the upstream boundary was obtained from the volume fraction of adjacent cells, and that on the downstream boundary was determined by the water level process. The numerical results agree with the observed data, and some conclusions can be drawn: after the foundation trench excavation, the flow velocity decreases quite a bit through the foundation trench, with reverse flow occurring on the lee slope in the foundation trench; the swirling flow impedes inflow, leading to the occurrence of dammed water above the foundation trench; the turbulent motion is stronger during ebbing than in other tidal stages, the range with the maximum value of turbulent viscosity, occurring on the south side of the foundation trench at maximum ebbing, is greater than those in other tidal stages in a tidal cycle, and the maximum value of Reynolds shear stress occurs on the south side of the foundation trench at maximum ebbing in a tidal cycle. The numerical calculation method shows a strong performance in simulation of the hydrodynamic characteristics of tidal currents in the foundation trench, providing a basis for submarine engineering construction in coastal areas.

关键词： Small-scale model Tidal current Hydrodynamic characteristic Coastal area Submarine excavation engineering Reynolds stress model

Non-interactive identity-based threshold signature scheme without random oracles

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第6期9卷 727-736页

作者： Xun SUN jian-hua li Shu-tang YANG Gong-liang CHEN Department of Electronic Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Information Security Engineering Shanghai Jiao Tong University Shanghai 200240 China

A (t, n) threshold signature scheme distributes the secret key and hence the signing ability to n players in a way that any set of t+1 or more honest players can collaborate to sign, while any set of t players cannot. In this paper we propose an iden- tity-based threshold signature (IBTHS) scheme from bilinear pairings. The signing phase of our scheme is non-interactive, meaning that the signing players do not need to talk to each other. We prove our scheme secure (i.e., unforgeable and robust) in the standard model (i.e., without random oracles). No earlier proposed IBTHS scheme achieved even one of the features of being non-interactive (in the signing phase) and secure in the standard model.

关键词： Bilinear pairings Identity-based threshold signature (IBTHS) Standard model

Security for cyberspace:challenges and opportunities

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Frontiers of Information Technology & Electronic Engineering 2018年第12期19卷 1459-1461页

作者： jiang-xing WU jian-hua li Xin-sheng JI National Digital Switching System Engineering & Technological R&D Center School of Cyber Security Shanghai Jiao Tong University

Nowadays,cyberspace has become the "fifth frontier"after the ocean,land,air,and *** the globalization of information,cyberspace has never faced so many challenges,such as principle innovation,theory innovation,technology innovation,and application ***,the transition from traditional cyberspace to new cyberspace is inevitable. In the future,cyberspace will have many important characteristics,such as openness,heterogeneity,mobility,dynamism,and security.

关键词： Security for cyberspace Sea land air space