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1.
0 INTRODUCTIONAcrackisusuallyregardedasofzero thicknessandinclosecontactwiththemediaoneithersideandthereisnocontactforcebetweencracks.Thecrackscansupportnotonlystressbutalsopullandshearingforce ,sothemediumbetweencrackskeepsthecon tinuumofstressanddispl…  相似文献   

2.
Inrecentyears,ferroelectricthinfilmsandtheirapplicationhavebecomeoneofthepopularresearchfieldsincondensedphysicsandsolidstateelectronics[1,2].Especiallytheriseofphysicsofferroelectricthinfilmsanditsapplicationforsolidstatefunctiondeviceshavepushedtheres…  相似文献   

3.
Benaloh[1]firstproposedtheconceptofhomomorphicsecretsharingschemesin1986.Infact,ahomomorphicsecretsharingschemeisasecretsharingschemewithanalgebraicstructure,ormoreprecisely,agroupstructureonitssecretspace,anditcanbeappliedtosecretvotingandsharedsignature[2…  相似文献   

4.
Oneoftheactualproblemsinasolid -statephysicsisnumericalcalculationsofphysicalpropertiesofsolids .Inthisworkwepresentthecomputercode″Dynam icsofcrystallattice″ .Thiscomputercodeisdevotedtothenumericalcalculationsofbasicphysicalpropertiesofcrystal.Theprima…  相似文献   

5.
Metalstructurestakeanimportantplaceingeneralscopeofstructuralconstructions .Theprincipalfieldoftheirusageishigh risers ,largetrussspanstructuresandindustrialbuildingswithcraneequipmentandextremetechnologicalprocess .Incomparisonwithreinforcedcon cretestr…  相似文献   

6.
Thedislocationemissionfromthecracktipandthenucleationandpropagationofmicrocrackscanbestudiedbyinsitutensiletestunderatransmissionelectronmicroscope(TEM)[1—3].However,thereisnostudyonatomicscalemicrostructureofcracktips,especiallyonthoseofloadedcracks.Fora…  相似文献   

7.
Inrecentyears,intelligentstructuresandsmartsystemshavebecomeahottopic.Becauseoftheirdirectandconversepiezoelectriceffects,piezoelectricmaterialshavebeenwidelyusedtomakevarioustransducersandactuatorsandhaveimportantapplicationsinhightechnologysuchasele…  相似文献   

8.
Electrodematerial,especiallyanodematerial,isadecisivefactorforthesuccessofanelectrolysistechnologicalprocess.Itssuperpotentialvalueisdirectlyrelatedtotheenergyconsumptionofdirectcurrentintheelectrolysisprocess.Itslifespanisthekeyintheindustrializati…  相似文献   

9.
1 IntroductionFerroelectricsceramic/polymercompositeswithdif ferentconnectivitypatternshaveattractedrecentresearchinterestsbecauseoftheirpotentialuseashigh energystoragecapacitordielectricsandastransducersandsen sorsinsmartsystems[1 3 ] .Oneoftheattractive…  相似文献   

10.
0 INTRODUCTIONMonitoringofmachiningprocess ,suchasmoni toringchatterandtoolwearinmilling ,isclassicprob lembasedonsignalprocessing .Signals (suchasvi bration ,forceandacousticemission)collectedbythesensorsaretypicallyaffectedbytheprocessdefects ,processworki…  相似文献   

11.
ZnOvaristorhasbeenwidelyusedinprotectiondevicesforsmalcurentelectroniccircuitsaswelasforlargecurenttransmisionlines[1].Theor...  相似文献   

12.
1 INTRODRCTIONWithregardtothestudyofcrystalgrowthunits,researchersmainlyconcentrateonthedissolutionofsolute ,theformationofgrowthunitsandthetransportationofthecrystalgrowthunittotheinterface ,aswellasthecongruencyofthegrowthunitsontheinter facesofthecry…  相似文献   

13.
Preparation of ITO nano-powders by hydrothermal-calcining process   总被引:4,自引:0,他引:4  
1 INTRODUCTIONSn-doped In2O3(ITO) is one kind of n-typesemiconductor material[1].It has excellent electro-optical properties , such as electrical conductivityand high transparency under visible light[2],andiswidely used in electronic , transparent electrode ,solar cells and electro-irradiance , especially inscreen display[3 ,4].Recently nearly half of the met-al indium has been used to prepare ITO materialsin the developed countries[5], such as Japan, A-merica ,France and so on.So the…  相似文献   

14.
Co/Al2O3 Fischer-Tropsch synthesis catalysts with different cobalt loadings were prepared using incipient wetness impregnation method. The effects of cobalt loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), temperature programmed reduction (TPR), hydrogen temperature programmed desorption (H2-TPD) and O2 titration. Co-support compound formation can be detected in catalyst system by XRD.For the Co/Al2O3 catalysts with low cobalt loading, CoAl2O3 phase appears visibly. Two different reduction regions can be presented for Co/Al2O3 catalysts, which belong to Co3 O4 crystallites (reduction at 320 ““C) and cobalt oxidealumina interaction species (reduction at above 400℃). Increasing Co loading results in the increase of Co3 O4 crystallite size. The reduced Co/Al2O3 catalysts have two adsorption sites, and cobalt loading greatly influences the adsorption behavior. With the increase of cobalt loading, the amount of low temperature adsorption is increased, the amount of high temperature adsorption is decreased, and the percentage reduction and cobalt crystallite size are increased.  相似文献   

15.
A new technology of treating molybdenum residues by simultaneous ultmfme milling and alkali leaching was put forward to recover molybdenum from metallurgical residues. The effects of residue size, milling time, solid content, n(Na2CO3)/n(Mo) and slurry pH value on molybdenum leaching rate were investigated. The results indicate that a simpler process, lower slurry temperature, 50% shorter treating time, 60% decrease of Na2CO3 content and 15% increase of molybdenum leaching rate can be obtained by the new technology compared with the traditional process. The leaching kinetic equation was determined, and calculation of active energy (E = 56.2 kJ/mol) shows that the leaching process of molybdenum residues by simultaneous ultmfine milling and alkali leaching is controlled by chemical reaction. Potential exists for the new process to form the basis for an economically viable, environmentally friendly process to recover valuable elements from residues.  相似文献   

16.
Al2 O3/Al composite was fabricated by the reaction between SiO2 and molten aluminum. The microstructures of the composite obtained under different reaction conditions were analyzed. The formation mechanism of the composite microstructure was discussed. Results show that the reaction kinetics is influenced remarkably by the reaction temperature, reaction time and the quantity of SiO2. The morphologies of Al2O3 have different features, depending on the reaction temperature. The composite has equaxed Al2O3 grains when materials reacted below 1200°C, and the composite is composed of a large number of fine Al2O3 grains and aluninum. The composite has a frame-shaped Al2O3 microstructure at the reaction temperature of above 1250°C. CHENG Xiao-min: Born in 1964 Funded by the National Natural Science Foundation of China (No. 91522)  相似文献   

17.
High-energy ball milling has a great influence on the temperature characters of synthetic reaction in Al-TiO2-C system by changing the size,distribution state and wet ability of reactants.Reaction temperature characters(reaction ignition time,ignition temperature time.the maximum temperature and temperature rising rate)were changed by different milling time.The longer the milling time.the earlier the reaction.the quicker the temperature rise and the higher the maximum temperature.When the milling time exceeded 10 hours,the reactivity of reactants was so high that the synthetic reaction could take place at 850℃ directly without a long time pretreatment at 670℃.The microstructure of synthetic composites became uniform and the reinforced particles(TiC and α-Al2O3)became fine with milling time increasing.  相似文献   

18.
A new C60 derivative—hydroxylated fullerene epoxide [C60 (OH) x (O) y ] was prepared by the reaction of C60 benzene solution with aqueous NaOH and H2O2 in the presence of tetrabutylammonium hydroxide (TBAH) as the catalyzer. The structure of hydroxylated fullerene epoxide was characterized by FT-IR, NMR and MS, and it was found that it is easy to hydrolyze to fullerol. Project supported by the Nonferrous Metals Industrial Corporation of China Synopsis of the first author Li Tianbao, doctoral student, born in 1965, major in Fullerence Chemistry and Materials.  相似文献   

19.
Decoloration and mineralization of yeast wastewater were investigated by using Ce-Fe/Al2O3 as a heterogeneous photo-Fenton catalyst in fluidized bed reactor in order to solve the problem of yeast wastewater discharge. The experimental results were assessed in terms of total organic carbon(TOC) reduction. The operational and reaction conditions affecting the efficiencies of TOC removal such as initial pH value, H2O2 concentration, catalyst loading and UV power were studied. The results show that TOC is reduced from 347.6 mg/L to 10.8 mg/L, color is changed from 500 units to 0 under the conditions as follows: initial pH value 6. 0, H2O2 concentration of 1. 000 g/L, catalyst loading of 5 g/L, reaction duration of 120 rain and reaction temperature of 30 ℃. The irradiated Ce-Fe/Al2O3 catalyst was complexed with 1,10-phenanthroline and then it was subjected to Fourier transform infrared spectroscopy and diffuse reflectance spectroscopy to confirm the formation of Fe(Ⅱ) in the solid state. Heterogeneous photo-Fenton reaction proves to be effective for the treatment of yeast wastewater.  相似文献   

20.
The reduction of Fe3O4 to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heating-up process, it is necessary to study the kinetics of the reaction. In this work, the first stage of reduction of magnetite cold bond pellets, that is the reduction from Fe3O4 to FeO, has been investigated using an isothermal thermogravimetric method. Isothermal experiments were carried out at 750°C, 800°C, 850°C and 900°C, respectively. The results showed that the reaction was controlled by chemical reaction below 800°C, whereas, at higher temperature, it was controlled by a mixed controlled mechanism of chemical reaction and Ginstling-Brounshtein diffusion as well. Project supported by the Nonferrous Metals Industrial Corporation of China Synopsis of the author Chen Qiyuan, professor, born in 1948. Major research fields: metallurgical thermodynamics and kinetics.  相似文献   

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