Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always...Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always struggle to balance mechanical properties and thermal insulation,resulting in their inability to meet the demands for both washing resistance and personal protection.Herein,inspired by the natural spring-like structures of cucumber tendrils,a superelastic and washable micro/nanofibrous sponge(MNFS)based on biomimetic helical fibers is directly prepared utilizing multiple-jet electrospinning technology for high-performance thermal insulation.By regulating the conductivity of polyvinylidene fluoride solution,multiple-jet ejection and multiple-stage whipping of jets are achieved,and further control of phase separation rates enables the rapid solidification of jets to form spring-like helical fibers,which are directly entangled to assemble MNFS.The resulting MNFS exhibits superelasticity that can withstand large tensile strain(200%),1000 cyclic tensile or compression deformations,and retain good resilience even in liquid nitrogen(-196℃).Furthermore,the MNFS shows efficient thermal insulation with low thermal conductivity(24.85 mW m^(-1)K^(-1)),close to the value of dry air,and remains structural stability even after cyclic washing.This work offers new possibilities for advanced fibrous sponges in transportation,environmental,and energy applications.展开更多
The article considers a relaxation of the water/polypropylene glycol-425 solution with a lower critical solution temperature(LCST)following its pulsed superheating concerning liquid-liquid and liquid-vapor equilibrium...The article considers a relaxation of the water/polypropylene glycol-425 solution with a lower critical solution temperature(LCST)following its pulsed superheating concerning liquid-liquid and liquid-vapor equilibrium lines,as well as the liquid-liquid spinodal.Superheating was performed using the pulsed heat generation method in a micro-sized wire probe.The main heating mode was the constant(over the pulse length)power mode.Characteristic heating rates ranged from 0.05×10^(5) to 2×10^(5) K/s,while the degree of superheating concerning the spinodal was up to 200 K.The temperature of spontaneous boiling-up and the amplitude of the corresponding signal were monitored as functions of the heating rate set by the power value.The results demonstrate an example of the interaction of liquidliquid and liquid-vapor phase transitions,as well as the spinodal decomposition of a solution with LCST against the background of its unstable states.We proposed a physical model to explain the minimum spontaneous boiling-up temperature revealed within a certain range of heating rates,which is not typical of completely miscible solutions.Further research will focus on establishing a general criterion for the possibility of spinodal decomposition of such solutions under the conditions of rapid heating.展开更多
Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/de...Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/desorption rate and excessive hydrogen absorption/desorption temperature limit the application of Mg-based hydrogen storage materials.The present paper reviews the advances in the research of Mg-based hydrogen storage film in recent years, including the advantage of the film, the function theory of fabricating method and its functional theory, and the influencing factors in the technological process. The research status worldwide is introduced in detail. By comparing pure Mg, Pd-caped Mg, nonpalladium capped Mg, and Mg alloy hydrogen storage films, an ideal tendency for producing Mg-based film is pointed out,for example, looking for a cheap metal element to replace the high-priced Pd, compositing Mg film with other hydrogen storage alloy of catalytic elements, and so on.展开更多
Multifactorial correlation analysis is a new method used to predict the land subsidence caused by groundwater exploitation This article introduces and applies the method to establish the function of the surface settle...Multifactorial correlation analysis is a new method used to predict the land subsidence caused by groundwater exploitation This article introduces and applies the method to establish the function of the surface settlement rate （Vs） and the function of the time-dependent surface settlement （St） caused by groundwater exploitation, based on data acquired at three land subsidence monitoring stations in the Hanoi area of Vietnam. Comparison with actual monitoring data indicates that the prediction results are relatively close to the monitoring data. From this, we conclude that multifactorial correlation analysis is a reliable method and can be used to predict future land subsidence caused by groundwater exploitation in Hanoi.展开更多
In this study, thermal–hydraulic parameters inside the containment of aWWER-1000/v446 nuclear power plant are simulated in a double-ended cold leg accident for short and long times (by using CONTAIN 2.0 and MELCOR 1....In this study, thermal–hydraulic parameters inside the containment of aWWER-1000/v446 nuclear power plant are simulated in a double-ended cold leg accident for short and long times (by using CONTAIN 2.0 and MELCOR 1.8.6 codes), and the effect of the spray system as an engineering safety feature on parameters mitigation is analyzed with the former code. Along with the development of the accident from design basis accident to beyond design basis accident, the Zircaloy–steam reaction becomes the source of in-vessel hydrogen generation. Hydrogen distribution inside the containment is simulated for a long time (using CONTAIN and MELCOR), and the effect of recombiners on its mitigation is analyzed (using MELCOR). Thermal–hydraulic parameters and hydrogen distribution profiles are presented as the outcome of the investigation. By activating the spray system, the peak points of pressure and temperature occur in the short time and remain belowthe maximumdesign values along the accident time. It is also shown that recombiners have a reliable effect on reducing the hydrogen concentration below flame propagation limit in the accident localization area. The parameters predicted by CONTAIN and MELCOR are in good agreement with the final safety analysis report. The noted discrepancies are discussed and explained.展开更多
Coking wastewater（CW） contains toxic and macromolecular substances that inhibit biological treatment. The refractory compounds remaining in biologically treated coking wastewater（BTCW） provide chemical oxygen dem...Coking wastewater（CW） contains toxic and macromolecular substances that inhibit biological treatment. The refractory compounds remaining in biologically treated coking wastewater（BTCW） provide chemical oxygen demand（COD） and color levels that make it unacceptable for reuse or disposal. Gas-phase pulsed corona discharge（PCD） utilizing mostly hydroxyl radicals and ozone as oxidants was applied to both raw coking wastewater（RCW） and BTCW wastewater as a supplemental treatment. The energy efficiency of COD,phenol, thiocyanate and cyanide degradation by PCD was the subject of the research. The cost-effective removal of intermediate oxidation products with addition of lime was also studied. The energy efficiency of oxidation was inversely proportional to the pulse repetition frequency： lower frequency allows more effective utilization of ozone at longer treatment times. Oxidative treatment of RCW showed the removal of phenol and thiocyanate at 800 pulses per second from 611 to 227 mg/L and from 348 to 86 mg/L, respectively, at 42 k Wh/m^3 delivered energy, with substantial improvement in the BOD5/COD ratio（from 0.14 to 0.43）.The COD and color of BTCW were removed by 30% and 93%, respectively, at 20 k Wh/m^3,showing energy efficiency for the PCD treatment exceeding that of conventional ozonation by a factor of 3–4. Application of lime appeared to be an effective supplement to the PCD treatment of RCW, degrading COD by about 28% at an energy input of 28 k Wh/m3 and the lime dose of 3.0 kg/m^3. The improvement of RCW treatability is attributed to the degradation of toxic substances and fragmentation of macromolecular compounds.展开更多
Non-isothermal oxidation of brown coal with 5 wt% of Cu(NO3)2, 5 wt% of Ce(NO3)3 and {2.5 wt% Cu(NO3)2 + 2.5 wt% Ce(NO3)3} additives was studied. The introduction of additives was carried out by an incipient wet impre...Non-isothermal oxidation of brown coal with 5 wt% of Cu(NO3)2, 5 wt% of Ce(NO3)3 and {2.5 wt% Cu(NO3)2 + 2.5 wt% Ce(NO3)3} additives was studied. The introduction of additives was carried out by an incipient wet impregnation method to ensure uniform distribution of cerium and copper nitrates within the structure of coal powdery samples (according to SEM and EDX mapping). The samples reactivity was studied in an isothermal oxidation regime at 200 °C (1 h) and by DSC/TGA at 2.5 °C/min heating rate. The additives implementation was found to reduce significantly the oxidation onset temperature (△Ti = 20-55 °C), the samples oxidation delay time (△ti= 2-22 min) and overall duration of the oxidation process (△tc = 8-16 min). The additives efficiency could be graded in accordance with the activation on the coal oxidation in the following row: Cu(NO3)2 >{Cu(NO3)2 + Ce(NO3)3}> Ce(NO3)3. According to the mass spectroscopy, the obtained row of activation correlates well with the initial temperature of the studied nitrate's decomposition (from 190 to 223 °C). A presence of nitrates was found to change significantly the trend of heat release taking place during the oxidation of coal samples (according to DSC/TGA data). The influence of coal morphology and volatiles concern in initial sample on the parameters of the oxidation process was studied as well. Activation energy (Ea) of the coal oxidation was calculated using Coats-Redfern method. Maximum decrease in Ea from 69 to 58 kJ/mol was observed for the samples with Cu(NO3)2. Graphical abstract.展开更多
Supershort avalanche electron beam(SAEB)plays an important role in nanosecond-pulse discharges.This paper aims at reviewing ex-periments results on characteritics of SAEB and its spectra in different gases in nanoseco...Supershort avalanche electron beam(SAEB)plays an important role in nanosecond-pulse discharges.This paper aims at reviewing ex-periments results on characteritics of SAEB and its spectra in different gases in nanosecond-pulse discharges.All the joint experiments were carried in the Institute of High Current Electronics of the Russian Academy of Sciences and the Institute of Electrical Engineering of the Chinese Academy of Sciences.In these experiments,the generation of a SAEB in SF 6 in an inhomogeneous electric field was studied on three generators with pulse rise times of 0.3,0.5 and~2 ns.Firstly,the comparison of SAEB parameters in SF 6 with those obtained in other gases(air,nitrogen,argon,and krypton)is introduced.Secondly,the SAEB spectra in SF 6 and air at pressures of 10 kPa(75 torr),and 0.1 MPa(750 torr)are reviewed and discussed.Finally,1.5-D theoretical simulation of the supershort pulse of the fast electron beam in a coaxial diode filled with SF 6 at atmospheric pressure is described.The simulation was carried out in the framework of hybrid model for discharge and runaway electron kinetics.The above research progress can provide better understanding of the investigation into the mechanism of nanosecond-pulse discharges.展开更多
This paper addressed the efect of copper acetate on the combustion characteristics of anthracite depending on the fractional composition of fuel and additive introduction method.Anthracite was impregnated with 5 wt%of...This paper addressed the efect of copper acetate on the combustion characteristics of anthracite depending on the fractional composition of fuel and additive introduction method.Anthracite was impregnated with 5 wt%of Cu(CH_(3)COO)_(2)by mechanical mixing and incipient wetness impregnation.Four anthracite samples of diferent fraction with d<0.1 mm,d=0.1-0.5 mm,d=0.5-1.0 mm,and d=1.0-2.0 mm were compared.According to EDX mapping,incipient wetness impregnation provides a higher dispersion of the additive and its uniform distribution in the sample.The ignition and combustion characteristics of the modifed anthracite samples were studied by thermal analysis and high-speed video recording of the processes in a combustion chamber(at heating medium temperature of 800℃).It was found that copper acetate increases anthracite reactivity,which was evidenced by decreased onset temperature of combustion(ΔT_(i))by 35-190℃and reduced ignition delay time(Δτ_(i))by 2.1-5.4 s.Copper acetate reduces fuel underburning(on average by 70%)in the ash residue of anthracite and decreases the amount of CO and NO_(x)in gas-phase products(on average by 18.5%and 20.8%,respectively).The mechanism for activation of anthracite combustion by copper acetate is proposed.展开更多
The paper proposes an experimental method of material inspection,which is based on digital processing of multi-frequency eddy current measurement data.The influences of various factors(conductivity,the gap between the...The paper proposes an experimental method of material inspection,which is based on digital processing of multi-frequency eddy current measurement data.The influences of various factors(conductivity,the gap between the sample surface and the sensor,the thickness of the sample) on the obtained hodographs are examined by taking the aluminum alloys for example,and the possibility of separation of various factors is analyzed.The results obtained are indicative of how much promise the proposed method offers for the inspection and testing of products made of aluminum alloys.展开更多
An effect of the high-power electromagnetic pulses onto the droplet of coal-water slurry inside the furnace was investigated.In contrary to the previously investigated laser-induced fuel atomization that occurs at the...An effect of the high-power electromagnetic pulses onto the droplet of coal-water slurry inside the furnace was investigated.In contrary to the previously investigated laser-induced fuel atomization that occurs at the room temperature,the pre-heated(to 400 K)slurry becomes dry enough to prevent the explosion-like steam formation.Thus,fuel does not atomize and the ignition does not accelerate.Furthermore,the absorption of several laser pulses leads to evident sintering of irradiated surface with following increase of the ignition delay time for up to 24%.Variation of the pulse energy in range 48-118 mJ(corresponding intensity up to 2.4 J·cm^-2)leads to certain variation of the increase of ignition delay.The strong pulsed overheating of the coal water slurry which does not initiate the fine atomization of the fuel generally makes its ignition longer.展开更多
This work presents the results of computer simulation of neutronic processes in a high-temperature gas-cooled thorium reactor for 30 different options of core loading.To guarantee stable and long-term reactor operatio...This work presents the results of computer simulation of neutronic processes in a high-temperature gas-cooled thorium reactor for 30 different options of core loading.To guarantee stable and long-term reactor operation(7-10 years),the quantity of fuel compact dispersion phase and starting fuel composition was selected.It is demonstrated that it is possible in principle to substitute the near-axial recirculation zone of the reactor core by a long magnetic trap with a high-temperature plasma column for generating thermonuclear neutrons.The distribution of neutron yield along the length of the plasma source is also presented.Such a thorium reactor,with a near-axial source of extra neutrons,can be applied for researching thermophysical and neutronic characteristics of dispersion thorium fuel to improve its properties.The results of the work are of great interest from the perspective of future advancement of the thermonuclear power industry,by means of creation of a hybrid installation based on a thorium reactor with a long plasma column as a source of additional neutrons.展开更多
A new type of neutron detector based on monocrystalline Si is developed to measure the fluence and flux density of thermal and fast neutrons.The principle of this detector is based on the relationship between changes ...A new type of neutron detector based on monocrystalline Si is developed to measure the fluence and flux density of thermal and fast neutrons.The principle of this detector is based on the relationship between changes in electrical conductivity and neutron fluence during irradiation.Therefore,the absolute values of thermal neutron fluence and flux density are measured in a facile manner with high reliability.Compared with activation methods,our method not only possesses a similar accuracy,but also demonstrates superior application potential for the investigation of neutron fields in nuclear reactors owing to its suitable half-life.展开更多
Using the methods of transmission electron microscopy, the carbide phase evolution in surface layers of the differentiallyquenched rails is studied after the passed tonnage of 691.8 million tons at the depth up to 10 ...Using the methods of transmission electron microscopy, the carbide phase evolution in surface layers of the differentiallyquenched rails is studied after the passed tonnage of 691.8 million tons at the depth up to 10 mm along the central axis andfillet of rail head. The action of two mutual supplement mechanisms of steel carbide phase transformation in surface layersat rail operation is established： （1） cutting mechanism of cementite particles with the following departure in the volume offerrite grains or plates （in pearlite structure）; （2） cutting mechanism and following dissolution of cementite particles,transfer of carbon atoms on dislocations （in Cottrell atmospheres and dislocation cores）, transfer of carbon atoms bymoving dislocations into ferrite grains volume （or plates） with the following repeated formation of nanosized cementiteparticles. The first mechanism is accompanied by the change in linear sizes and morphology of carbide particles. Cementiteelement composition change is not essential. Carbide structure change can take place during the second mechanism.展开更多
Crystal defect engineering is widely used as an effective approach to regulate the optical and optoelectronic properties of semiconductor nanostructures.However,photogenerated electron-hole pair recombination centers ...Crystal defect engineering is widely used as an effective approach to regulate the optical and optoelectronic properties of semiconductor nanostructures.However,photogenerated electron-hole pair recombination centers caused by structural defects usually lead to the reduction of optoelectronic performance.In this work,a high-performance photodetector based on(GaN)_(1-x)(ZnO)_(x)solid solution nanowire with bicrystal structure is fabricated and it shows excellent photoresponse to ultraviolet and visible light.The highest responsivity of the photodetector is as high as 60,86 and 43 A/W under the irradiation of365 nm,532 nm and 650 nm,respectively.The corresponding response time is as fast as 170,320 and 160 ms.Such wide spectral responses can be attributed to various intermediate energy levels induced by the introduction of various structural defects and dopants in the solid solution nanowire.Moreover,the peculiar bicrystal boundary along the axial direction of the nanowire provides two parallel and fast transmission channels for photo-generated carriers,reducing the recombination of photo-generated carriers.Our findings provide a valued example using crystal defect engineering to broaden the photoresponse range and improve the photodetector performance and thus can be extended to other material systems for various optoelectronic applications.展开更多
Two ligands, 1, 3-bis(4-carboxyphenyl)imidazolium chloride and 4, 4-bipyridine, were employed to prepare nickel and zinc azolium based MOFs, Ni-MOF and Zn-MOF by the mixed ligand solvothermal approach. The positively ...Two ligands, 1, 3-bis(4-carboxyphenyl)imidazolium chloride and 4, 4-bipyridine, were employed to prepare nickel and zinc azolium based MOFs, Ni-MOF and Zn-MOF by the mixed ligand solvothermal approach. The positively charged azolium moieties in the imidazolium linker resulted in a charged environment in the as-synthesized frameworks. As a result, Ni-MOF and Zn-MOF demonstrated preferential adsorption of CO_(2) over methane molecules in the gas phase adsorption due to the higher quadruple moment of CO_(2), which interacts more with the positively charged frameworks. Besides, in aqueous media, Ni-MOF and Zn-MOF exhibited incredible adsorption efficiency for anionic dyes. In the following, Ni-MOF was metallated at the carbene site of the azolium linker to generate the novel heterogeneous catalyst Pd/Ni-MOF, which was successfully applied for Sonogashira and Suzuki-Miyaura coupling reactions without losing its activity after three cycles.展开更多
High-current ion beams have become a powerful tool for improving the surface properties of different materials.The prospects of wide commercial use of such beams for material treatment is not only due to the possibili...High-current ion beams have become a powerful tool for improving the surface properties of different materials.The prospects of wide commercial use of such beams for material treatment is not only due to the possibility of improving their properties,but,also for economic expediency.To achieve a high throughput and reduce the cost on ion beam material treatment,ion beams of high average and pulsed power are necessary.This paper gives an overview of work on generation of pulsed and repetitively pulsed beams of accelerated ions with currents ranging from fractions of an ampere to several tens of kA and with pulse duration from several tens of nanoseconds to several hundreds of microseconds.A number of different methods of materials surface properties modification using high power and intense ion beam and plasma are considered.展开更多
Free volume is an extremely important intrinsic defect in polymers. Structurally, free volume is the randomly distributed holes in the polymer molecular chain segments. In proton exchange membrane fuel cells, free vol...Free volume is an extremely important intrinsic defect in polymers. Structurally, free volume is the randomly distributed holes in the polymer molecular chain segments. In proton exchange membrane fuel cells, free volume is also the space needed for the directional conduction of protons. Irradiation by α particles to grafting sulfonated poly(vinylidene fluoride)(PVDF) is one of the methods to produce proton exchange membrane with good proton channel rate. Positron annihilation lifetime spectroscopy was used to study the free volume size at different absorbed dose levels from 0.13 MGy to 0.65 MGy. Measurement method of positron annihilation lifetime spectroscopy for PVDF based on ^(44) Ti positron source was developed. For low dose irradiation at 0.26 MGy, a decrease in free volume and practically unchanged crystallinity were observed. Further increase of absorbed dose range from 0.26 MGy to 0.39 MGy led to an increasing crystallinity with the same free volume level. For the absorbed dose from 0.39 MGy to 0.65 MGy, crystallinity was decreased but free volume remained almost constant.展开更多
We study the absorption of hydrogen of metal by the permeability method. With the help of the gas reaction controller(GRC), the absorptive capacity of hydrogen, which is a function of time, temperature and pressure, c...We study the absorption of hydrogen of metal by the permeability method. With the help of the gas reaction controller(GRC), the absorptive capacity of hydrogen, which is a function of time, temperature and pressure, can be recorded. The effect of the performance of the hydrogen permeability of AlN coating on the titanium alloy surface structure is studied.In the research, the AlN is selected to be added to the titanium alloy sample VT6, and the properties of the titanium alloy are investigated, and the hydrogen absorption rate of the coating is calculated by performing the hydrogen saturation of the test sample. The results show that under 600℃ the AlN film reduces the hydrogen absorption rate of titanium alloy and improves the surface properties of VT6 alloy.展开更多
The research deals with the methodology intended to root robust quality indices in the interval control system, the parameters of which are affinely included in the coefficients of a characteristic polynomial. To dete...The research deals with the methodology intended to root robust quality indices in the interval control system, the parameters of which are affinely included in the coefficients of a characteristic polynomial. To determine the root quality indices we propose to depict on the root plane not all edges of the interval parametric polytope(as the edge theorem says), but its particular vertex-edge route. In order to define this route we need to know the angle sequence at which the edge branches depart from any integrated pole on the allocation area. It is revealed that the edge branches can integrate into the route both fully or partially due to intersection with other branches. The conditions which determine the intersection of one-face edge images have been proven. It is shown that the root quality indices can be determined by its ends or by any other internal point depending on a type of edge branch. The conditions which allow determining the edge branch type have been identified. On the basis of these studies we developed the algorithm intended to construct a boundary vertex-edge route on the polytope with the interval parameters of the system. As an illustration of how the algorithm can be implemented, we determined and introduced the root indices reflecting the robust quality of the system used to stabilize the position of an underwater charging station for autonomous unmanned vehicles.展开更多
基金supported by Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2022QNRC001)the National Natural Science Foundation of China(No.52273053)the Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.21CGA41)。
文摘Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always struggle to balance mechanical properties and thermal insulation,resulting in their inability to meet the demands for both washing resistance and personal protection.Herein,inspired by the natural spring-like structures of cucumber tendrils,a superelastic and washable micro/nanofibrous sponge(MNFS)based on biomimetic helical fibers is directly prepared utilizing multiple-jet electrospinning technology for high-performance thermal insulation.By regulating the conductivity of polyvinylidene fluoride solution,multiple-jet ejection and multiple-stage whipping of jets are achieved,and further control of phase separation rates enables the rapid solidification of jets to form spring-like helical fibers,which are directly entangled to assemble MNFS.The resulting MNFS exhibits superelasticity that can withstand large tensile strain(200%),1000 cyclic tensile or compression deformations,and retain good resilience even in liquid nitrogen(-196℃).Furthermore,the MNFS shows efficient thermal insulation with low thermal conductivity(24.85 mW m^(-1)K^(-1)),close to the value of dry air,and remains structural stability even after cyclic washing.This work offers new possibilities for advanced fibrous sponges in transportation,environmental,and energy applications.
基金the expense of a grant of the Russian Science Foundation(project No.23-69-10006),https://rscf.ru/project/23-69-10006/(accessed on 6 May 2025).
文摘The article considers a relaxation of the water/polypropylene glycol-425 solution with a lower critical solution temperature(LCST)following its pulsed superheating concerning liquid-liquid and liquid-vapor equilibrium lines,as well as the liquid-liquid spinodal.Superheating was performed using the pulsed heat generation method in a micro-sized wire probe.The main heating mode was the constant(over the pulse length)power mode.Characteristic heating rates ranged from 0.05×10^(5) to 2×10^(5) K/s,while the degree of superheating concerning the spinodal was up to 200 K.The temperature of spontaneous boiling-up and the amplitude of the corresponding signal were monitored as functions of the heating rate set by the power value.The results demonstrate an example of the interaction of liquidliquid and liquid-vapor phase transitions,as well as the spinodal decomposition of a solution with LCST against the background of its unstable states.We proposed a physical model to explain the minimum spontaneous boiling-up temperature revealed within a certain range of heating rates,which is not typical of completely miscible solutions.Further research will focus on establishing a general criterion for the possibility of spinodal decomposition of such solutions under the conditions of rapid heating.
基金Project supported by the Competitiveness Enhancement Program of National Research Tomsk Polytechnic University(Grant No.VIU-OEF-66/2019)
文摘Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/desorption rate and excessive hydrogen absorption/desorption temperature limit the application of Mg-based hydrogen storage materials.The present paper reviews the advances in the research of Mg-based hydrogen storage film in recent years, including the advantage of the film, the function theory of fabricating method and its functional theory, and the influencing factors in the technological process. The research status worldwide is introduced in detail. By comparing pure Mg, Pd-caped Mg, nonpalladium capped Mg, and Mg alloy hydrogen storage films, an ideal tendency for producing Mg-based film is pointed out,for example, looking for a cheap metal element to replace the high-priced Pd, compositing Mg film with other hydrogen storage alloy of catalytic elements, and so on.
基金supported by Vietnam National Funds of Education and Training
文摘Multifactorial correlation analysis is a new method used to predict the land subsidence caused by groundwater exploitation This article introduces and applies the method to establish the function of the surface settlement rate （Vs） and the function of the time-dependent surface settlement （St） caused by groundwater exploitation, based on data acquired at three land subsidence monitoring stations in the Hanoi area of Vietnam. Comparison with actual monitoring data indicates that the prediction results are relatively close to the monitoring data. From this, we conclude that multifactorial correlation analysis is a reliable method and can be used to predict future land subsidence caused by groundwater exploitation in Hanoi.
基金Part of this research has been developed under the auspices of EU H2020 Union’s Horizon 2020 research and innovation programme Marie Sklodowska-Curie Actions COFUND Grant SIRCIW,Agreement No.663830.
文摘In this study, thermal–hydraulic parameters inside the containment of aWWER-1000/v446 nuclear power plant are simulated in a double-ended cold leg accident for short and long times (by using CONTAIN 2.0 and MELCOR 1.8.6 codes), and the effect of the spray system as an engineering safety feature on parameters mitigation is analyzed with the former code. Along with the development of the accident from design basis accident to beyond design basis accident, the Zircaloy–steam reaction becomes the source of in-vessel hydrogen generation. Hydrogen distribution inside the containment is simulated for a long time (using CONTAIN and MELCOR), and the effect of recombiners on its mitigation is analyzed (using MELCOR). Thermal–hydraulic parameters and hydrogen distribution profiles are presented as the outcome of the investigation. By activating the spray system, the peak points of pressure and temperature occur in the short time and remain belowthe maximumdesign values along the accident time. It is also shown that recombiners have a reliable effect on reducing the hydrogen concentration below flame propagation limit in the accident localization area. The parameters predicted by CONTAIN and MELCOR are in good agreement with the final safety analysis report. The noted discrepancies are discussed and explained.
基金supported by the Special Foundation for Applied Science and Technology of Guangdong Province(No.2015B020235005)the National Natural Science Foundation of China(No.51278199)The PCD device was designed at Tomsk Polytechnic University within the framework of Tomsk Polytechnic University Competitiveness Enhancement Program grant
文摘Coking wastewater（CW） contains toxic and macromolecular substances that inhibit biological treatment. The refractory compounds remaining in biologically treated coking wastewater（BTCW） provide chemical oxygen demand（COD） and color levels that make it unacceptable for reuse or disposal. Gas-phase pulsed corona discharge（PCD） utilizing mostly hydroxyl radicals and ozone as oxidants was applied to both raw coking wastewater（RCW） and BTCW wastewater as a supplemental treatment. The energy efficiency of COD,phenol, thiocyanate and cyanide degradation by PCD was the subject of the research. The cost-effective removal of intermediate oxidation products with addition of lime was also studied. The energy efficiency of oxidation was inversely proportional to the pulse repetition frequency： lower frequency allows more effective utilization of ozone at longer treatment times. Oxidative treatment of RCW showed the removal of phenol and thiocyanate at 800 pulses per second from 611 to 227 mg/L and from 348 to 86 mg/L, respectively, at 42 k Wh/m^3 delivered energy, with substantial improvement in the BOD5/COD ratio（from 0.14 to 0.43）.The COD and color of BTCW were removed by 30% and 93%, respectively, at 20 k Wh/m^3,showing energy efficiency for the PCD treatment exceeding that of conventional ozonation by a factor of 3–4. Application of lime appeared to be an effective supplement to the PCD treatment of RCW, degrading COD by about 28% at an energy input of 28 k Wh/m3 and the lime dose of 3.0 kg/m^3. The improvement of RCW treatability is attributed to the degradation of toxic substances and fragmentation of macromolecular compounds.
文摘Non-isothermal oxidation of brown coal with 5 wt% of Cu(NO3)2, 5 wt% of Ce(NO3)3 and {2.5 wt% Cu(NO3)2 + 2.5 wt% Ce(NO3)3} additives was studied. The introduction of additives was carried out by an incipient wet impregnation method to ensure uniform distribution of cerium and copper nitrates within the structure of coal powdery samples (according to SEM and EDX mapping). The samples reactivity was studied in an isothermal oxidation regime at 200 °C (1 h) and by DSC/TGA at 2.5 °C/min heating rate. The additives implementation was found to reduce significantly the oxidation onset temperature (△Ti = 20-55 °C), the samples oxidation delay time (△ti= 2-22 min) and overall duration of the oxidation process (△tc = 8-16 min). The additives efficiency could be graded in accordance with the activation on the coal oxidation in the following row: Cu(NO3)2 >{Cu(NO3)2 + Ce(NO3)3}> Ce(NO3)3. According to the mass spectroscopy, the obtained row of activation correlates well with the initial temperature of the studied nitrate's decomposition (from 190 to 223 °C). A presence of nitrates was found to change significantly the trend of heat release taking place during the oxidation of coal samples (according to DSC/TGA data). The influence of coal morphology and volatiles concern in initial sample on the parameters of the oxidation process was studied as well. Activation energy (Ea) of the coal oxidation was calculated using Coats-Redfern method. Maximum decrease in Ea from 69 to 58 kJ/mol was observed for the samples with Cu(NO3)2. Graphical abstract.
基金The work on the experimental setup#1 and#2 was sup-ported by grants RFBR#15-58-53031_ГФЕН_аThe work on the experimental setup#3 was supported by the National Natural Science Foundation of China under Contract#51511130040.
文摘Supershort avalanche electron beam(SAEB)plays an important role in nanosecond-pulse discharges.This paper aims at reviewing ex-periments results on characteritics of SAEB and its spectra in different gases in nanosecond-pulse discharges.All the joint experiments were carried in the Institute of High Current Electronics of the Russian Academy of Sciences and the Institute of Electrical Engineering of the Chinese Academy of Sciences.In these experiments,the generation of a SAEB in SF 6 in an inhomogeneous electric field was studied on three generators with pulse rise times of 0.3,0.5 and~2 ns.Firstly,the comparison of SAEB parameters in SF 6 with those obtained in other gases(air,nitrogen,argon,and krypton)is introduced.Secondly,the SAEB spectra in SF 6 and air at pressures of 10 kPa(75 torr),and 0.1 MPa(750 torr)are reviewed and discussed.Finally,1.5-D theoretical simulation of the supershort pulse of the fast electron beam in a coaxial diode filled with SF 6 at atmospheric pressure is described.The simulation was carried out in the framework of hybrid model for discharge and runaway electron kinetics.The above research progress can provide better understanding of the investigation into the mechanism of nanosecond-pulse discharges.
文摘This paper addressed the efect of copper acetate on the combustion characteristics of anthracite depending on the fractional composition of fuel and additive introduction method.Anthracite was impregnated with 5 wt%of Cu(CH_(3)COO)_(2)by mechanical mixing and incipient wetness impregnation.Four anthracite samples of diferent fraction with d<0.1 mm,d=0.1-0.5 mm,d=0.5-1.0 mm,and d=1.0-2.0 mm were compared.According to EDX mapping,incipient wetness impregnation provides a higher dispersion of the additive and its uniform distribution in the sample.The ignition and combustion characteristics of the modifed anthracite samples were studied by thermal analysis and high-speed video recording of the processes in a combustion chamber(at heating medium temperature of 800℃).It was found that copper acetate increases anthracite reactivity,which was evidenced by decreased onset temperature of combustion(ΔT_(i))by 35-190℃and reduced ignition delay time(Δτ_(i))by 2.1-5.4 s.Copper acetate reduces fuel underburning(on average by 70%)in the ash residue of anthracite and decreases the amount of CO and NO_(x)in gas-phase products(on average by 18.5%and 20.8%,respectively).The mechanism for activation of anthracite combustion by copper acetate is proposed.
基金supported by Program for Basic Scientific Research of the State Academies of Sciences for 2013e2020the RF Ministry of Education and Science (Contract No. 02.G25.31.0063)
文摘The paper proposes an experimental method of material inspection,which is based on digital processing of multi-frequency eddy current measurement data.The influences of various factors(conductivity,the gap between the sample surface and the sensor,the thickness of the sample) on the obtained hodographs are examined by taking the aluminum alloys for example,and the possibility of separation of various factors is analyzed.The results obtained are indicative of how much promise the proposed method offers for the inspection and testing of products made of aluminum alloys.
基金performed within the framework of the Russian State Assignment“Science”project FSWW-2020-0022Investigations of the ignition techniques of waste-derived fuels were partially supported by the Tomsk Polytechnic University Competitiveness Enhancement Program(project VIU-ISHFVP-197/2019).
文摘An effect of the high-power electromagnetic pulses onto the droplet of coal-water slurry inside the furnace was investigated.In contrary to the previously investigated laser-induced fuel atomization that occurs at the room temperature,the pre-heated(to 400 K)slurry becomes dry enough to prevent the explosion-like steam formation.Thus,fuel does not atomize and the ignition does not accelerate.Furthermore,the absorption of several laser pulses leads to evident sintering of irradiated surface with following increase of the ignition delay time for up to 24%.Variation of the pulse energy in range 48-118 mJ(corresponding intensity up to 2.4 J·cm^-2)leads to certain variation of the increase of ignition delay.The strong pulsed overheating of the coal water slurry which does not initiate the fine atomization of the fuel generally makes its ignition longer.
文摘This work presents the results of computer simulation of neutronic processes in a high-temperature gas-cooled thorium reactor for 30 different options of core loading.To guarantee stable and long-term reactor operation(7-10 years),the quantity of fuel compact dispersion phase and starting fuel composition was selected.It is demonstrated that it is possible in principle to substitute the near-axial recirculation zone of the reactor core by a long magnetic trap with a high-temperature plasma column for generating thermonuclear neutrons.The distribution of neutron yield along the length of the plasma source is also presented.Such a thorium reactor,with a near-axial source of extra neutrons,can be applied for researching thermophysical and neutronic characteristics of dispersion thorium fuel to improve its properties.The results of the work are of great interest from the perspective of future advancement of the thermonuclear power industry,by means of creation of a hybrid installation based on a thorium reactor with a long plasma column as a source of additional neutrons.
基金the support of the TPU Competitiveness Improvement Program(2030).
文摘A new type of neutron detector based on monocrystalline Si is developed to measure the fluence and flux density of thermal and fast neutrons.The principle of this detector is based on the relationship between changes in electrical conductivity and neutron fluence during irradiation.Therefore,the absolute values of thermal neutron fluence and flux density are measured in a facile manner with high reliability.Compared with activation methods,our method not only possesses a similar accuracy,but also demonstrates superior application potential for the investigation of neutron fields in nuclear reactors owing to its suitable half-life.
基金supported by Russian Scientific Foundation(Project No.15-12-00010)
文摘Using the methods of transmission electron microscopy, the carbide phase evolution in surface layers of the differentiallyquenched rails is studied after the passed tonnage of 691.8 million tons at the depth up to 10 mm along the central axis andfillet of rail head. The action of two mutual supplement mechanisms of steel carbide phase transformation in surface layersat rail operation is established： （1） cutting mechanism of cementite particles with the following departure in the volume offerrite grains or plates （in pearlite structure）; （2） cutting mechanism and following dissolution of cementite particles,transfer of carbon atoms on dislocations （in Cottrell atmospheres and dislocation cores）, transfer of carbon atoms bymoving dislocations into ferrite grains volume （or plates） with the following repeated formation of nanosized cementiteparticles. The first mechanism is accompanied by the change in linear sizes and morphology of carbide particles. Cementiteelement composition change is not essential. Carbide structure change can take place during the second mechanism.
基金partially supported by the National Natural Science Foundation of China(Nos.51702326 and 51872296)the Liaoning Province Natural Science Foundation(No.2019-MS333)+3 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2019197)the Shenyang National Laboratory for Materials Science(No.L2019F36)the Shenyang Planning Project of Science and Technology(No.18-013-0-52)Tomsk Polytechnic University Competitiveness Enhancement Program grant with project number TPU CEP NOC N.M.Kizhnera188/2020。
文摘Crystal defect engineering is widely used as an effective approach to regulate the optical and optoelectronic properties of semiconductor nanostructures.However,photogenerated electron-hole pair recombination centers caused by structural defects usually lead to the reduction of optoelectronic performance.In this work,a high-performance photodetector based on(GaN)_(1-x)(ZnO)_(x)solid solution nanowire with bicrystal structure is fabricated and it shows excellent photoresponse to ultraviolet and visible light.The highest responsivity of the photodetector is as high as 60,86 and 43 A/W under the irradiation of365 nm,532 nm and 650 nm,respectively.The corresponding response time is as fast as 170,320 and 160 ms.Such wide spectral responses can be attributed to various intermediate energy levels induced by the introduction of various structural defects and dopants in the solid solution nanowire.Moreover,the peculiar bicrystal boundary along the axial direction of the nanowire provides two parallel and fast transmission channels for photo-generated carriers,reducing the recombination of photo-generated carriers.Our findings provide a valued example using crystal defect engineering to broaden the photoresponse range and improve the photodetector performance and thus can be extended to other material systems for various optoelectronic applications.
文摘Two ligands, 1, 3-bis(4-carboxyphenyl)imidazolium chloride and 4, 4-bipyridine, were employed to prepare nickel and zinc azolium based MOFs, Ni-MOF and Zn-MOF by the mixed ligand solvothermal approach. The positively charged azolium moieties in the imidazolium linker resulted in a charged environment in the as-synthesized frameworks. As a result, Ni-MOF and Zn-MOF demonstrated preferential adsorption of CO_(2) over methane molecules in the gas phase adsorption due to the higher quadruple moment of CO_(2), which interacts more with the positively charged frameworks. Besides, in aqueous media, Ni-MOF and Zn-MOF exhibited incredible adsorption efficiency for anionic dyes. In the following, Ni-MOF was metallated at the carbene site of the azolium linker to generate the novel heterogeneous catalyst Pd/Ni-MOF, which was successfully applied for Sonogashira and Suzuki-Miyaura coupling reactions without losing its activity after three cycles.
基金support of the Russian Foundation of Fundamental Investigations(grant No.10-08-00828-a)
文摘High-current ion beams have become a powerful tool for improving the surface properties of different materials.The prospects of wide commercial use of such beams for material treatment is not only due to the possibility of improving their properties,but,also for economic expediency.To achieve a high throughput and reduce the cost on ion beam material treatment,ion beams of high average and pulsed power are necessary.This paper gives an overview of work on generation of pulsed and repetitively pulsed beams of accelerated ions with currents ranging from fractions of an ampere to several tens of kA and with pulse duration from several tens of nanoseconds to several hundreds of microseconds.A number of different methods of materials surface properties modification using high power and intense ion beam and plasma are considered.
文摘Free volume is an extremely important intrinsic defect in polymers. Structurally, free volume is the randomly distributed holes in the polymer molecular chain segments. In proton exchange membrane fuel cells, free volume is also the space needed for the directional conduction of protons. Irradiation by α particles to grafting sulfonated poly(vinylidene fluoride)(PVDF) is one of the methods to produce proton exchange membrane with good proton channel rate. Positron annihilation lifetime spectroscopy was used to study the free volume size at different absorbed dose levels from 0.13 MGy to 0.65 MGy. Measurement method of positron annihilation lifetime spectroscopy for PVDF based on ^(44) Ti positron source was developed. For low dose irradiation at 0.26 MGy, a decrease in free volume and practically unchanged crystallinity were observed. Further increase of absorbed dose range from 0.26 MGy to 0.39 MGy led to an increasing crystallinity with the same free volume level. For the absorbed dose from 0.39 MGy to 0.65 MGy, crystallinity was decreased but free volume remained almost constant.
基金Project supported by the China Scholarship Council
文摘We study the absorption of hydrogen of metal by the permeability method. With the help of the gas reaction controller(GRC), the absorptive capacity of hydrogen, which is a function of time, temperature and pressure, can be recorded. The effect of the performance of the hydrogen permeability of AlN coating on the titanium alloy surface structure is studied.In the research, the AlN is selected to be added to the titanium alloy sample VT6, and the properties of the titanium alloy are investigated, and the hydrogen absorption rate of the coating is calculated by performing the hydrogen saturation of the test sample. The results show that under 600℃ the AlN film reduces the hydrogen absorption rate of titanium alloy and improves the surface properties of VT6 alloy.
基金supported by the Ministry of Education and Science of the Russian Federation (No. 2.3649. 2017/PCh)
文摘The research deals with the methodology intended to root robust quality indices in the interval control system, the parameters of which are affinely included in the coefficients of a characteristic polynomial. To determine the root quality indices we propose to depict on the root plane not all edges of the interval parametric polytope(as the edge theorem says), but its particular vertex-edge route. In order to define this route we need to know the angle sequence at which the edge branches depart from any integrated pole on the allocation area. It is revealed that the edge branches can integrate into the route both fully or partially due to intersection with other branches. The conditions which determine the intersection of one-face edge images have been proven. It is shown that the root quality indices can be determined by its ends or by any other internal point depending on a type of edge branch. The conditions which allow determining the edge branch type have been identified. On the basis of these studies we developed the algorithm intended to construct a boundary vertex-edge route on the polytope with the interval parameters of the system. As an illustration of how the algorithm can be implemented, we determined and introduced the root indices reflecting the robust quality of the system used to stabilize the position of an underwater charging station for autonomous unmanned vehicles.
