Pilbara blending iron ore powder （PB powder） is blending ores with good and poor quality iron ores, so how to use PB power effectively is a problem. The self-characteristics of PB powder and its single-components we...Pilbara blending iron ore powder （PB powder） is blending ores with good and poor quality iron ores, so how to use PB power effectively is a problem. The self-characteristics of PB powder and its single-components were studied respectively such as the macroscopic properties, microscopic properties, and high-temperature properties the behavior and effect in the sintering were mastered. Then based on the new ore-proportioning idea of iron ores sintering characteristics complementary, the principles on the effective use of PB powder were discussed, and was fur ther validated through the sintering pot test and industrial production. The results show that PB powder is composed of three kinds of iron ore, and the sintering characteristics of different iron ores are obviously discrepant. With the ore-proportioning optimization based on the iron ores sintering characteristics complementary, the proportion of PB iron ore powder can be increased to more than 45 %.展开更多
The optimum coating composition of alkali Fe powder welding rods was designed by orthogonal experiment with mix rates. A new kind of effective RE-Fe powder welding rod was prepared which could be used at the condition...The optimum coating composition of alkali Fe powder welding rods was designed by orthogonal experiment with mix rates. A new kind of effective RE-Fe powder welding rod was prepared which could be used at the condition of direct and indirect current. The arc characteristics and stabilities of effective Fe powder welding rods containing RE were analyzed by HANNOVER analyzer. The efficiency of Fe powder welding rods was tested by weighting method. It was found that the stability of Fe powder welding rods was improved when it was added with rare earths. The results of impact experiment at low temperatures and SEM analysis on impact break showed that the grain was refined, the welding joint was cleaned, and the mechanical properties of joint was enhanced with proper RE content. It was provided with good processing property for this effective RE-Fe powder welding rod, and its efficiency could arrive at 180%.展开更多
A comparative study is carried out for the nonlinear propagation of ion acoustic shock waves both for the weakly and highly relativistic plasmas consisting of relativistic ions and qdistributed electrons and positions...A comparative study is carried out for the nonlinear propagation of ion acoustic shock waves both for the weakly and highly relativistic plasmas consisting of relativistic ions and qdistributed electrons and positions.The Burgers equation is derived to reveal the physical phenomena using the well known reductive perturbation technique.The integration of the Burgers equation is performed by the（G￠/G）-expansion method.The effects of positron concentration,ion–electron temperature ratio,electron–positron temperature ratio,ion viscosity coefficient,relativistic streaming factor and the strength of the electron and positron nonextensivity on the nonlinear propagation of ion acoustic shock and periodic waves are presented graphically and the relevant physical explanations are provided.展开更多
Objective To explore the feasibility and efficacy of desensitization protocol for highly sensitized renal transplant patients ( HSP ) . Methods Thirty - five HSPs ( HLA class - I panel reactive antibody 2〉50 % ) , in...Objective To explore the feasibility and efficacy of desensitization protocol for highly sensitized renal transplant patients ( HSP ) . Methods Thirty - five HSPs ( HLA class - I panel reactive antibody 2〉50 % ) , including 27 patients with a positive T and/or B cell cy-展开更多
The evaporation behaviors are crucial for the flame location estimation in liquid rocketengines.This work,for the first time,experimentally reports the sub-millimeter droplet evaporationcharacteristics of the corrosiv...The evaporation behaviors are crucial for the flame location estimation in liquid rocketengines.This work,for the first time,experimentally reports the sub-millimeter droplet evaporationcharacteristics of the corrosive dinitrogen tetroxide(NTO,one prevailing hypergolic oxidizer)athigh ambient pressure up to 4.5 MPa.An in-house corrosion-resistant droplet generator is usedto generate isolated flying droplets of sub-millimeter size,which are then exposed in a gas environ-ment with temperatures between 1010 K and 1210 K and pressures in the range between 2.0 MPaand 4.5 MPa,provided by an optical rapid compression machine.Parallelly,a theoretical modelconsidering both the droplet ambient convection and the NTO dissociation is developed.Resultsindicate that firstly,the present theoretical model that considers the transient droplet-ambient con-vection as well as the temperature and pressure dependent rate of dissociation shows good agree-ment with the experimentally observed droplet lifetime.In addition,the flying droplets velocityregress gradually due to momentum exchange with the ambient,which is more prominent at higherpressure.The evaporation caused droplet size reduction is consistent with the classical D^(2)-law pre-diction,in the present temperature and pressure range.Finally,higher temperature and pressureaccelerate the evaporation and an empirical correlation for the temperature and pressure dependentevaporation rate constant is proposed,which shows good agreement with experiment and simula-tion results.展开更多
The inferior structure/electrochemistry stability due to the volume expansion and the less lithium storage active sites of transition metal oxide (TMO) are critical issue hindering their commercialization.The rational...The inferior structure/electrochemistry stability due to the volume expansion and the less lithium storage active sites of transition metal oxide (TMO) are critical issue hindering their commercialization.The rational design to utilize the combined advantages of both structure and composition is a key strategy to address these challenges.Here,the (FeCoNiMnCrMg)_(2)O_(3)high entropy oxide(HEO) with different morphologic structures are developed through integrating molecule and microstructure engineering.The morphologic structure of high entropy oxide transforms from solid spheres to multishelled core-shell spheres,and then to hollow spheres,which is governed by a thermally induced non-uniform shrinkage process coupled with Kirkendall effect diffusion due to the different calcination temperature.Even with the incorporation of various metallic ions,the high entropy oxide with a homogeneous single-phase solid solution maintained their shape and uniformity in size due to the ability of metal ions to coexist on the same lattice point.Benefiting from the meticulous control of both compositional and geometric factors,the hollow high entropy oxide exhibited a significantly high specific capacity (1722.1 mAh g^(-1)after 200cycles at 1 A g^(-1)) and long-life span for lithium storage(2158.7 mAh g^(-1)over 900 cycles at 4 A g^(-1)).The collaborative lattice and consistent volume demonstrated in this study offer significant potential in directing the development of materials for advanced energy storage solutions.展开更多
The role of entropy and enthalpy plays an essential key for the formation of an alloy. This paper illustrates how an alloy is to form and what and why the properties of the alloy are going to have by the entropy and e...The role of entropy and enthalpy plays an essential key for the formation of an alloy. This paper illustrates how an alloy is to form and what and why the properties of the alloy are going to have by the entropy and enthalpy effects via a designed enthalpy-entropy plane (EE-plane) based on the Gibbs free energy equation and the introducing a charactering pseudo-unitary lattice (PUL) for entropy alloys. Based on the PUL scheme, the so-called four effects in high entropy alloys are simply nothing but the entropy effect with the other three accompanying effects: the distortion, slow diffusion and cocktail effects.展开更多
Static mechanical experiments were carried out on granite after and under different temperatures using an electro-hydraulic and servo-controlled material testing machine with a heating device. Variations in obvious fo...Static mechanical experiments were carried out on granite after and under different temperatures using an electro-hydraulic and servo-controlled material testing machine with a heating device. Variations in obvious form, stress-strain curve, peak strength, peak strain and elastic modulus with temperature were analyzed and the essence of rock failure modes was explored. The results indicate that, compared with granite after the high temperature treatment, the brittle-ductile transition critical temperature is lower, the densification stage is longer, the elastic modulus is smaller and the damage is larger under high temperature. In addition, the peak stress is lower and the peak strain is greater, but both of them change more obviously with the increase of temperature compared with that of granite after the high temperature treatment. Furthermore, the failure modes of granite after the high temperature treatment and under high temperature show a remarkable difference. Below 100 ℃, the failure modes of granite under both conditions are the same, presenting splitting failure. However, after 100 ℃, the failure modes of granite after the high temperature treatment and under high temperature present splitting failure and shear failure, respectively.展开更多
Based on the 3D electron's radial wave function of Co 2+ free ion,a Nephelauxetic effect modifying factor to modify the radial wave function is introduced when Co 2+ cations are put into the crystal fie...Based on the 3D electron's radial wave function of Co 2+ free ion,a Nephelauxetic effect modifying factor to modify the radial wave function is introduced when Co 2+ cations are put into the crystal field of Zn 1-x Co x Se.With the modified wave functions,the optical transitions for Zn 1-x Co x Se crystals are calculated.Moreover,based on the first principle of physics,the influences of high pressure to the Nephelauxetic effect modifying factor is considered,and the high pressure blue shift for the Zn 1-x Co x Se crystal absorption spectra are calculated and a shift rate of d E /d p =0 45meV/GPa is obtained.展开更多
Objective To probe into the effective acupuncture treatment for high fever and other clinical relevant symptoms in common cold. Methods Based on randoming and multi-central clinical trial principle, the included 276 c...Objective To probe into the effective acupuncture treatment for high fever and other clinical relevant symptoms in common cold. Methods Based on randoming and multi-central clinical trial principle, the included 276 cases were randomized into experimental group （138 cases） and control group （138 cases） in statistics. Electric acupuncture on Dazhui（大椎 GV14） was applied in experimental group and the injection with antondine was in control group. The immediate antipyretic and clinical therapeutic effects were observed in 24 h. Results The body temperatures at different times in experimental group were all lower than those in control group after treatment （P〈 0.01 ）. The scores of relevant symptoms in 3- 24 h after treatment were lower than those in control group （P〈0.05）. The response time （1.42± 1.79） h in experimental group was shorter than that （3.44±5.10） h in control group （P〈0.05）. The response times for chills, soreness of limbs, headach and sweating in experimental group were shorter than those in control group （P〈0. 01 ）. The recovery times for chills and headache in experimental group were shorter than those in control group （P〈0.05）. The systematic therapeutic effects were different significantly between two groups in 24 h （P〈0.05）. Conclusion Acupuncture on Dazhui（大椎 GV14） had achieved definite effects on treatment for high fever in common cold. It released remarkably chills, soreness of limbs, headache and sweating and improved the systematic therapeutic effects on common cold.展开更多
The mechanical properties of limestone such as the stress-strain curve, the variable characteristics of peak strength and the modulus of elasticity of limestone were studied under the action of temperatures ranging fr...The mechanical properties of limestone such as the stress-strain curve, the variable characteristics of peak strength and the modulus of elasticity of limestone were studied under the action of temperatures ranging from room temperature to 800 °C.Our results show that:1) the temperature has not clear effect on the mechanical properties of limestone from room temperature to 600 °C.However, the mechanical properties of limestone deteriorate rapidly when the temperature is above 600 °C.In this case, the peak stress and modulus of elasticity decrease rapidly.When the temperature reaches 800 °C, the entire process, showing the stress-strain curve is displayed indicating an obvious state of plastic-deformation;2) the failure mode of limestone shows the breakdown of tensile strength from room temperature to 600 °C, as well as the compress shearing damage over 600 °C;3) combining our test results with the concept of thermal damage, a thermal damage equation was derived.展开更多
In order to address the current aircraft noise problem, the knowledge of impedance of acoustic liners subjected to high-intensity sound and grazing flow is of crucial importance to the design of high-efficiency acoust...In order to address the current aircraft noise problem, the knowledge of impedance of acoustic liners subjected to high-intensity sound and grazing flow is of crucial importance to the design of high-efficiency acoustic nacelles. To this end, the present study is twofold. Firstly, the StraightForward impedance eduction Method(SFM) is evaluated by the strategy that the impedance of a liner specimen is firstly experimentally educed on a flow duct using the SFM, and then its accuracy is checked by comparing the numerical prediction with the measured wall sound pressure of the flow duct. Secondly, the effects of grazing flow and high-intensity sound on the impedance behavior of two single-layer liners are investigated based on comparisons between educed impedance and predictions by three impedance models. The performance of the SFM is validated by showing that the educed impedance leads to excellent agreement between the simulation and the measured wall sound pressure for different grazing flow Mach numbers and Sound Pressure Levels(SPLs) and over a frequency range from 3000 Hz down to 500 Hz. The grazing flow effect generally has the tendency that the acoustic resistance exhibits a slight decrease before it increases linearly with an increase in Mach,predicted successfully by the sound-vortex interaction theoretical model and the Kooi semi-empirical impedance model. However, the Goodrich semi-empirical impedance model gives only a simple linear relation of acoustic resistance starting from Mach zero. Additionally, when the SPL increases from 110 to 140 d B in the present investigation, the acoustic resistance exhibits a significant increase at all frequencies in the absence of flow; however, the resistance decreases slightly under a grazing flow of Mach 0.117. It indicates that the SPL effect can be greatly inhibited when flow is present,and the grazing flow effect can be reduced partly as well at a relatively high SPL.展开更多
In order to improve the wear resistance of titanium alloy Ti6Al4V and high temperature oxidation resistance of intermetallic compound TiAl, the Double Glow Plasma Surface Alloying Technique (DG technique) was applied ...In order to improve the wear resistance of titanium alloy Ti6Al4V and high temperature oxidation resistance of intermetallic compound TiAl, the Double Glow Plasma Surface Alloying Technique (DG technique) was applied to modify the surface properties of these materials. Mo, Nb, Cr, Ni were diffused into the substrate materials to form alloyed layers with different properties. This paper shows the microstructure, microhardnesses, distributions of the alloy elements on the alloyed layers. Wear and high temperature oxidation tests were carried out. Test results indicate that the wear resistance of Ti6Al4V and the high temperature oxidation resistance of TiAl were improved significantly.展开更多
With lignite after vacuum drying as the raw material,a series of Zn-based sorbents were prepared by static impregnation,ultrasonic-assisted impregnation,bubbling-assisted impregnation and high-pressure impregnation.Th...With lignite after vacuum drying as the raw material,a series of Zn-based sorbents were prepared by static impregnation,ultrasonic-assisted impregnation,bubbling-assisted impregnation and high-pressure impregnation.The physical properties and the desulfurization performances of Zn-based sorbents were studied systematically by XRD,BET,AAS characterization techniques and the fixed-bed desulfurization evaluation apparatus.The sorbents obtained by high-pressure impregnation method have a larger specific surface area,pore volume and pore diameter comparing with other methods,which is conducive to the sulfidation reaction of hydrogen sulfide gas in the sorbent.The effects of pressure during the high-pressure impregnation and concentration of Zn(NO3)2 precursor solution on the sorbents properties and desulfurization behavior were investigated.The higher the impregnation pressure and the concentration of impregnation solution are,the greater the amount of the active components are uploaded.However,overhigh impregnation pressure can cause collapse and blocking of the carrier pore.The optimal operating condition of high-pressure impregnation method for preparing the sorbents was the impregnation pressure of 20 atm and the solution concentration of 41%.Under that condition,the sorbent had the best desulfurization ability with a sulfur capacity of 13.94 gS/100 gsorbent and a breakthrough time of 54 h.Its desulfurization precision and efficiency of removing H2S before sorbent breakthrough from the middle temperature gases of 400℃ can reach【5 ppm and】99%,respectively.Sorbents could be regenerated under the condition of 1 vol%O2,20 vol% H2O,0.5 vol% NH3,and N2balance gas.The regenerated sorbent could be used for repeated absorption of H2S with a slight decrease in desulfurization effect.展开更多
A NiCrAlY coating was prepared on the cast Ni-base superalloy K17 using arc ion plating. The coating was uniform, dense and well adhesive to the substrate. The oxidation kinetic curves of the alloy K17 and the coating...A NiCrAlY coating was prepared on the cast Ni-base superalloy K17 using arc ion plating. The coating was uniform, dense and well adhesive to the substrate. The oxidation kinetic curves of the alloy K17 and the coating were obtained. The results indicated that the oxidation resistance of the alloy K17 was evidently improved with NiCrAlY coatings at 900∼1100°C. As oxidation temperature rising, the interdiffusion between the coatings and substrates was enhanced. Ti atoms diffused from the substrate to the surface of coating to form the oxide, which was one of the reasons for the decrement of oxidation resistance. The oxidation resistance of NiCrAlY coating was decreased due to the spalling of pieces of oxide.展开更多
Thermal conductivity(k)of iron is measured up to about 134 GPa.The measurements are carried out using the single sided laser heated diamond anvil cell,where the power absorbed by a Fe metal foil at hotspot is calculat...Thermal conductivity(k)of iron is measured up to about 134 GPa.The measurements are carried out using the single sided laser heated diamond anvil cell,where the power absorbed by a Fe metal foil at hotspot is calculated using a novel thermodynamical method.Thermal conductivity of fee(γ)-Fe increases up to a pressure of about46 GPa.We find thermal conductivity values in the range of 70-80 Wm-1K-1(with an uncertainty of 40%),almost constant with pressure,in the hcp(e)phase of Fe.We attribute the pressure independent k above 46 GPa to the strong electronic correlation effects driven by the electronic topological transition(ETT).We predict a value of thermal conductivity ofε-Fe of about 40±16 Wm-1K-1 at the outer core of Earth.展开更多
The microstructure, martensite transformation behavior, thermal stability and shape memory behavior of Ti–20Zr– 10Ta high temperature shape memory alloy were investigated. The Ti–20Zr–10Ta alloy exhibited a revers...The microstructure, martensite transformation behavior, thermal stability and shape memory behavior of Ti–20Zr– 10Ta high temperature shape memory alloy were investigated. The Ti–20Zr–10Ta alloy exhibited a reversible transformation with the high martensite transformation temperature of 500oC and good thermal stability. The alloy displayed the elongation of 15% and a maximum recovery stain of 5.5% with 8% pre-strain.展开更多
In recent years, the usages of by-products and wastes in industry have become more important. The importance of the sustainable development is also of increasing. The utilizations of wastes, as mineral admixture or fi...In recent years, the usages of by-products and wastes in industry have become more important. The importance of the sustainable development is also of increasing. The utilizations of wastes, as mineral admixture or fine aggregate, reduce the consumption of the natural resources and improve the durability of concrete. In this study, the effect of the fineness on the high temperature and sulphate resistances of concrete mortar specimens, produced with ground granulated blast-furnace slag (GBFS) replacing cement, is investigated. The compressive and flexural strength test results for all series related to durability effects, exposing temperature and solutions, exposure times for these durability effects, slag content and fineness are discussed. Conse- quently, the optimum slag contents are determined for producing the sulphate and high temperature resistant mortars.展开更多
The structural stability and electrical properties of AlB2-type MnB2 were studied based on high pressure angledispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell(DAC) and firs...The structural stability and electrical properties of AlB2-type MnB2 were studied based on high pressure angledispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell(DAC) and first-principles calculations under high pressure. The x-ray diffraction results show that the structure of AlB2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9±3.7 GPa with a fixed pressure derivative of 4, which indicates that AlB2-type MnB2 is a hard and incompressible material. The electrical resistance undergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.展开更多
文摘Pilbara blending iron ore powder （PB powder） is blending ores with good and poor quality iron ores, so how to use PB power effectively is a problem. The self-characteristics of PB powder and its single-components were studied respectively such as the macroscopic properties, microscopic properties, and high-temperature properties the behavior and effect in the sintering were mastered. Then based on the new ore-proportioning idea of iron ores sintering characteristics complementary, the principles on the effective use of PB powder were discussed, and was fur ther validated through the sintering pot test and industrial production. The results show that PB powder is composed of three kinds of iron ore, and the sintering characteristics of different iron ores are obviously discrepant. With the ore-proportioning optimization based on the iron ores sintering characteristics complementary, the proportion of PB iron ore powder can be increased to more than 45 %.
文摘The optimum coating composition of alkali Fe powder welding rods was designed by orthogonal experiment with mix rates. A new kind of effective RE-Fe powder welding rod was prepared which could be used at the condition of direct and indirect current. The arc characteristics and stabilities of effective Fe powder welding rods containing RE were analyzed by HANNOVER analyzer. The efficiency of Fe powder welding rods was tested by weighting method. It was found that the stability of Fe powder welding rods was improved when it was added with rare earths. The results of impact experiment at low temperatures and SEM analysis on impact break showed that the grain was refined, the welding joint was cleaned, and the mechanical properties of joint was enhanced with proper RE content. It was provided with good processing property for this effective RE-Fe powder welding rod, and its efficiency could arrive at 180%.
文摘A comparative study is carried out for the nonlinear propagation of ion acoustic shock waves both for the weakly and highly relativistic plasmas consisting of relativistic ions and qdistributed electrons and positions.The Burgers equation is derived to reveal the physical phenomena using the well known reductive perturbation technique.The integration of the Burgers equation is performed by the（G￠/G）-expansion method.The effects of positron concentration,ion–electron temperature ratio,electron–positron temperature ratio,ion viscosity coefficient,relativistic streaming factor and the strength of the electron and positron nonextensivity on the nonlinear propagation of ion acoustic shock and periodic waves are presented graphically and the relevant physical explanations are provided.
文摘Objective To explore the feasibility and efficacy of desensitization protocol for highly sensitized renal transplant patients ( HSP ) . Methods Thirty - five HSPs ( HLA class - I panel reactive antibody 2〉50 % ) , including 27 patients with a positive T and/or B cell cy-
基金supported by the Natural Science Foundation of China(No.52236001)The support from Research Grants Council of Hong Kong,China(No.CityU 15218820)was also appreciated。
文摘The evaporation behaviors are crucial for the flame location estimation in liquid rocketengines.This work,for the first time,experimentally reports the sub-millimeter droplet evaporationcharacteristics of the corrosive dinitrogen tetroxide(NTO,one prevailing hypergolic oxidizer)athigh ambient pressure up to 4.5 MPa.An in-house corrosion-resistant droplet generator is usedto generate isolated flying droplets of sub-millimeter size,which are then exposed in a gas environ-ment with temperatures between 1010 K and 1210 K and pressures in the range between 2.0 MPaand 4.5 MPa,provided by an optical rapid compression machine.Parallelly,a theoretical modelconsidering both the droplet ambient convection and the NTO dissociation is developed.Resultsindicate that firstly,the present theoretical model that considers the transient droplet-ambient con-vection as well as the temperature and pressure dependent rate of dissociation shows good agree-ment with the experimentally observed droplet lifetime.In addition,the flying droplets velocityregress gradually due to momentum exchange with the ambient,which is more prominent at higherpressure.The evaporation caused droplet size reduction is consistent with the classical D^(2)-law pre-diction,in the present temperature and pressure range.Finally,higher temperature and pressureaccelerate the evaporation and an empirical correlation for the temperature and pressure dependentevaporation rate constant is proposed,which shows good agreement with experiment and simula-tion results.
基金financially supported by the Central Guidance on Local Science and Technology Development Fund of Sichuan Province(No.2023ZYDF044)LingYan Project(No.2024C01090)
文摘The inferior structure/electrochemistry stability due to the volume expansion and the less lithium storage active sites of transition metal oxide (TMO) are critical issue hindering their commercialization.The rational design to utilize the combined advantages of both structure and composition is a key strategy to address these challenges.Here,the (FeCoNiMnCrMg)_(2)O_(3)high entropy oxide(HEO) with different morphologic structures are developed through integrating molecule and microstructure engineering.The morphologic structure of high entropy oxide transforms from solid spheres to multishelled core-shell spheres,and then to hollow spheres,which is governed by a thermally induced non-uniform shrinkage process coupled with Kirkendall effect diffusion due to the different calcination temperature.Even with the incorporation of various metallic ions,the high entropy oxide with a homogeneous single-phase solid solution maintained their shape and uniformity in size due to the ability of metal ions to coexist on the same lattice point.Benefiting from the meticulous control of both compositional and geometric factors,the hollow high entropy oxide exhibited a significantly high specific capacity (1722.1 mAh g^(-1)after 200cycles at 1 A g^(-1)) and long-life span for lithium storage(2158.7 mAh g^(-1)over 900 cycles at 4 A g^(-1)).The collaborative lattice and consistent volume demonstrated in this study offer significant potential in directing the development of materials for advanced energy storage solutions.
文摘The role of entropy and enthalpy plays an essential key for the formation of an alloy. This paper illustrates how an alloy is to form and what and why the properties of the alloy are going to have by the entropy and enthalpy effects via a designed enthalpy-entropy plane (EE-plane) based on the Gibbs free energy equation and the introducing a charactering pseudo-unitary lattice (PUL) for entropy alloys. Based on the PUL scheme, the so-called four effects in high entropy alloys are simply nothing but the entropy effect with the other three accompanying effects: the distortion, slow diffusion and cocktail effects.
基金Projects(51304241,11472311,51322403)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China+1 种基金Project(2016zzts456)supported by Independent Exploration and Innovation Foundation of Central South University,ChinaProject(2015CB060200)supported by the National Basic Research Program of China
文摘Static mechanical experiments were carried out on granite after and under different temperatures using an electro-hydraulic and servo-controlled material testing machine with a heating device. Variations in obvious form, stress-strain curve, peak strength, peak strain and elastic modulus with temperature were analyzed and the essence of rock failure modes was explored. The results indicate that, compared with granite after the high temperature treatment, the brittle-ductile transition critical temperature is lower, the densification stage is longer, the elastic modulus is smaller and the damage is larger under high temperature. In addition, the peak stress is lower and the peak strain is greater, but both of them change more obviously with the increase of temperature compared with that of granite after the high temperature treatment. Furthermore, the failure modes of granite after the high temperature treatment and under high temperature show a remarkable difference. Below 100 ℃, the failure modes of granite under both conditions are the same, presenting splitting failure. However, after 100 ℃, the failure modes of granite after the high temperature treatment and under high temperature present splitting failure and shear failure, respectively.
文摘Based on the 3D electron's radial wave function of Co 2+ free ion,a Nephelauxetic effect modifying factor to modify the radial wave function is introduced when Co 2+ cations are put into the crystal field of Zn 1-x Co x Se.With the modified wave functions,the optical transitions for Zn 1-x Co x Se crystals are calculated.Moreover,based on the first principle of physics,the influences of high pressure to the Nephelauxetic effect modifying factor is considered,and the high pressure blue shift for the Zn 1-x Co x Se crystal absorption spectra are calculated and a shift rate of d E /d p =0 45meV/GPa is obtained.
文摘Objective To probe into the effective acupuncture treatment for high fever and other clinical relevant symptoms in common cold. Methods Based on randoming and multi-central clinical trial principle, the included 276 cases were randomized into experimental group （138 cases） and control group （138 cases） in statistics. Electric acupuncture on Dazhui（大椎 GV14） was applied in experimental group and the injection with antondine was in control group. The immediate antipyretic and clinical therapeutic effects were observed in 24 h. Results The body temperatures at different times in experimental group were all lower than those in control group after treatment （P〈 0.01 ）. The scores of relevant symptoms in 3- 24 h after treatment were lower than those in control group （P〈0.05）. The response time （1.42± 1.79） h in experimental group was shorter than that （3.44±5.10） h in control group （P〈0.05）. The response times for chills, soreness of limbs, headach and sweating in experimental group were shorter than those in control group （P〈0. 01 ）. The recovery times for chills and headache in experimental group were shorter than those in control group （P〈0.05）. The systematic therapeutic effects were different significantly between two groups in 24 h （P〈0.05）. Conclusion Acupuncture on Dazhui（大椎 GV14） had achieved definite effects on treatment for high fever in common cold. It released remarkably chills, soreness of limbs, headache and sweating and improved the systematic therapeutic effects on common cold.
基金Projects 50490273 supported by the National Natural Science Foundation of China2007CB209400 by the National Basic Research Program of China+1 种基金08KJD130003 by the Basic Research Program of University in Jiangsu ProvinceXKY2007219 by Xuzhou Institute of Technology
文摘The mechanical properties of limestone such as the stress-strain curve, the variable characteristics of peak strength and the modulus of elasticity of limestone were studied under the action of temperatures ranging from room temperature to 800 °C.Our results show that:1) the temperature has not clear effect on the mechanical properties of limestone from room temperature to 600 °C.However, the mechanical properties of limestone deteriorate rapidly when the temperature is above 600 °C.In this case, the peak stress and modulus of elasticity decrease rapidly.When the temperature reaches 800 °C, the entire process, showing the stress-strain curve is displayed indicating an obvious state of plastic-deformation;2) the failure mode of limestone shows the breakdown of tensile strength from room temperature to 600 °C, as well as the compress shearing damage over 600 °C;3) combining our test results with the concept of thermal damage, a thermal damage equation was derived.
基金co-supported by the National Natural Science Foundation of China (No. 51576009)the Projects of International Cooperation and Exchanges National Natural Science Foundation of China (Nos.11661141020 and 51711530036)
文摘In order to address the current aircraft noise problem, the knowledge of impedance of acoustic liners subjected to high-intensity sound and grazing flow is of crucial importance to the design of high-efficiency acoustic nacelles. To this end, the present study is twofold. Firstly, the StraightForward impedance eduction Method(SFM) is evaluated by the strategy that the impedance of a liner specimen is firstly experimentally educed on a flow duct using the SFM, and then its accuracy is checked by comparing the numerical prediction with the measured wall sound pressure of the flow duct. Secondly, the effects of grazing flow and high-intensity sound on the impedance behavior of two single-layer liners are investigated based on comparisons between educed impedance and predictions by three impedance models. The performance of the SFM is validated by showing that the educed impedance leads to excellent agreement between the simulation and the measured wall sound pressure for different grazing flow Mach numbers and Sound Pressure Levels(SPLs) and over a frequency range from 3000 Hz down to 500 Hz. The grazing flow effect generally has the tendency that the acoustic resistance exhibits a slight decrease before it increases linearly with an increase in Mach,predicted successfully by the sound-vortex interaction theoretical model and the Kooi semi-empirical impedance model. However, the Goodrich semi-empirical impedance model gives only a simple linear relation of acoustic resistance starting from Mach zero. Additionally, when the SPL increases from 110 to 140 d B in the present investigation, the acoustic resistance exhibits a significant increase at all frequencies in the absence of flow; however, the resistance decreases slightly under a grazing flow of Mach 0.117. It indicates that the SPL effect can be greatly inhibited when flow is present,and the grazing flow effect can be reduced partly as well at a relatively high SPL.
文摘In order to improve the wear resistance of titanium alloy Ti6Al4V and high temperature oxidation resistance of intermetallic compound TiAl, the Double Glow Plasma Surface Alloying Technique (DG technique) was applied to modify the surface properties of these materials. Mo, Nb, Cr, Ni were diffused into the substrate materials to form alloyed layers with different properties. This paper shows the microstructure, microhardnesses, distributions of the alloy elements on the alloyed layers. Wear and high temperature oxidation tests were carried out. Test results indicate that the wear resistance of Ti6Al4V and the high temperature oxidation resistance of TiAl were improved significantly.
基金supported by the National Basic Research Program of China(2012CB723105)the National Natural Science Foundation of China(20976117)Shanxi Graduates Excellent Innovation Project of China(tyut-rc201018a)
文摘With lignite after vacuum drying as the raw material,a series of Zn-based sorbents were prepared by static impregnation,ultrasonic-assisted impregnation,bubbling-assisted impregnation and high-pressure impregnation.The physical properties and the desulfurization performances of Zn-based sorbents were studied systematically by XRD,BET,AAS characterization techniques and the fixed-bed desulfurization evaluation apparatus.The sorbents obtained by high-pressure impregnation method have a larger specific surface area,pore volume and pore diameter comparing with other methods,which is conducive to the sulfidation reaction of hydrogen sulfide gas in the sorbent.The effects of pressure during the high-pressure impregnation and concentration of Zn(NO3)2 precursor solution on the sorbents properties and desulfurization behavior were investigated.The higher the impregnation pressure and the concentration of impregnation solution are,the greater the amount of the active components are uploaded.However,overhigh impregnation pressure can cause collapse and blocking of the carrier pore.The optimal operating condition of high-pressure impregnation method for preparing the sorbents was the impregnation pressure of 20 atm and the solution concentration of 41%.Under that condition,the sorbent had the best desulfurization ability with a sulfur capacity of 13.94 gS/100 gsorbent and a breakthrough time of 54 h.Its desulfurization precision and efficiency of removing H2S before sorbent breakthrough from the middle temperature gases of 400℃ can reach【5 ppm and】99%,respectively.Sorbents could be regenerated under the condition of 1 vol%O2,20 vol% H2O,0.5 vol% NH3,and N2balance gas.The regenerated sorbent could be used for repeated absorption of H2S with a slight decrease in desulfurization effect.
文摘A NiCrAlY coating was prepared on the cast Ni-base superalloy K17 using arc ion plating. The coating was uniform, dense and well adhesive to the substrate. The oxidation kinetic curves of the alloy K17 and the coating were obtained. The results indicated that the oxidation resistance of the alloy K17 was evidently improved with NiCrAlY coatings at 900∼1100°C. As oxidation temperature rising, the interdiffusion between the coatings and substrates was enhanced. Ti atoms diffused from the substrate to the surface of coating to form the oxide, which was one of the reasons for the decrement of oxidation resistance. The oxidation resistance of NiCrAlY coating was decreased due to the spalling of pieces of oxide.
基金Ministry of Earth Sciences,Government of India for financial support under the project grant no.MoES/16/25/10-RDEASDST,INSPIRE program by Department of Science and Technology,Government of India for financial support。
文摘Thermal conductivity(k)of iron is measured up to about 134 GPa.The measurements are carried out using the single sided laser heated diamond anvil cell,where the power absorbed by a Fe metal foil at hotspot is calculated using a novel thermodynamical method.Thermal conductivity of fee(γ)-Fe increases up to a pressure of about46 GPa.We find thermal conductivity values in the range of 70-80 Wm-1K-1(with an uncertainty of 40%),almost constant with pressure,in the hcp(e)phase of Fe.We attribute the pressure independent k above 46 GPa to the strong electronic correlation effects driven by the electronic topological transition(ETT).We predict a value of thermal conductivity ofε-Fe of about 40±16 Wm-1K-1 at the outer core of Earth.
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 51071059 and 51271065） and the National Basic Research Program of China （Grant Nt）. 2012CB619400）
文摘The microstructure, martensite transformation behavior, thermal stability and shape memory behavior of Ti–20Zr– 10Ta high temperature shape memory alloy were investigated. The Ti–20Zr–10Ta alloy exhibited a reversible transformation with the high martensite transformation temperature of 500oC and good thermal stability. The alloy displayed the elongation of 15% and a maximum recovery stain of 5.5% with 8% pre-strain.
文摘In recent years, the usages of by-products and wastes in industry have become more important. The importance of the sustainable development is also of increasing. The utilizations of wastes, as mineral admixture or fine aggregate, reduce the consumption of the natural resources and improve the durability of concrete. In this study, the effect of the fineness on the high temperature and sulphate resistances of concrete mortar specimens, produced with ground granulated blast-furnace slag (GBFS) replacing cement, is investigated. The compressive and flexural strength test results for all series related to durability effects, exposing temperature and solutions, exposure times for these durability effects, slag content and fineness are discussed. Conse- quently, the optimum slag contents are determined for producing the sulphate and high temperature resistant mortars.
基金Project supported by the National Basic Research Program of China （Grant No. 2011CB808200）, the Program for Changjiang Scholars and Innovative Re- search Team in University, China （Grant No. IRT1132）, the National Natural Science Foundation of China （Grant Nos. 51032001, 11074090, 10979001, and 51025206）, and the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences （Grant No. DE-AC02-98CH 10886）.
文摘The structural stability and electrical properties of AlB2-type MnB2 were studied based on high pressure angledispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell(DAC) and first-principles calculations under high pressure. The x-ray diffraction results show that the structure of AlB2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9±3.7 GPa with a fixed pressure derivative of 4, which indicates that AlB2-type MnB2 is a hard and incompressible material. The electrical resistance undergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.
