Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial ...Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial Coulombic efficiency (ICE) due to severe structural degradation caused by irreversible O release.Herein,we introduce a three-in-one strategy of increasing Ni and Mn content,along with Li/Ni disordering and TM–O covalency regulation to boost cationic and anionic redox activity simultaneously and thus enhance the electrochemical activity of LLOs.The target material,Li_(1.2)Ni_(0.168)Mn_(0.558)Co_(0.074)O_(2)(L1),exhibits an improved ICE of 87.2%and specific capacity of 293.2 mA h g^(-1)and minimal voltage decay of less than 0.53 m V cycle-1over 300 cycles at 1C,compared to Li_(1.2)Ni_(0.13)Mn_(0.54)Co_(0.13)O_(2)(Ls)(274.4 mA h g^(-1)for initial capacity,73.8%for ICE and voltage decay of 0.84 mV/cycle over 300 cycles at 1C).Theoretical calculations reveal that the density of states (DOS) area near the Fermi energy level for L1 is larger than that of Ls,indicating higher anionic and cationic redox reactivity than Ls.Moreover,L1 exhibits increased O-vacancy formation energy due to higher Li/Ni disordering of 4.76%(quantified by X-ray diffraction Rietveld refinement) and enhanced TM–O covalency,making lattice O release more difficult and thus improving electrochemical stability.The increased Li/Ni disordering also leads to more Ni^(2+)presence in the Li layer,which acts as a pillar during Li+de-embedding,improving structural stability.This research not only presents a viable approach to designing low-Co LLOs with enhanced capacity and ICE but also contributes significantly to the fundamental understanding of structural regulation in high-performance LIB cathodes.展开更多
Excessive emissions of nitrogen oxides from flue gas have imposed various detrimental impacts on environment,and the development of deNO_(x) catalysts with low-cost and high performance is an urgent requirement.Iron o...Excessive emissions of nitrogen oxides from flue gas have imposed various detrimental impacts on environment,and the development of deNO_(x) catalysts with low-cost and high performance is an urgent requirement.Iron oxide-based material has been explored for promising deNO_(x) catalysts.However,the unsatisfactory low-temperature activity limits their practical applications.In this study,a series of excellent low-temperature denitrification catalysts(Ha-FeO_(x)/yZS)were prepared by acid treatment of zinc slag,and the mass ratios of Fe to impure ions was regulated by adjusting the acid concentrations.Ha-FeO_(x)/yZS showed high denitrification performance(>90%)in the range of 180–300℃,and the optimal NO conversion and N2 selectivity were higher than 95%at 250℃.Among them,the Ha-FeO_(x)/2ZS synthesized with 2 mol/L HNO3 exhibited the widest temperature window(175–350℃).The excellent denitrification performance of Ha-FeO_(x)/yZS was mainly attributed to the strong interaction between Fe and impurity ions to inhibit the growth of crystals,making Ha-FeO_(x)/yZS with amorphous structure,nice fine particles,large specific surface area,more surface acid sites and high chemisorbed oxygen.The in-situ DRIFT experiments confirmed that the SCR reaction on the Ha-FeO_(x)/yZS followed both Langmuir-Hinshelwood(L-H)mechanism and Eley-Rideal(E-R)mechanism.The present work proposed a high value-added method for the preparation of cost-effective catalysts from zinc slag,which showed a promising application prospect in NO_(x) removal by selective catalytic reduction with ammonia.展开更多
As interest in double perovskites is growing,especially in applications like photovoltaic devices,understanding their mechanical properties is vital for device durability.Despite extensive exploration of structure and...As interest in double perovskites is growing,especially in applications like photovoltaic devices,understanding their mechanical properties is vital for device durability.Despite extensive exploration of structure and optical properties,research on mechanical aspects is limited.This article builds a vacancyordered double perovskite model,employing first-principles calculations to analyze mechanical,bonding,electronic,and optical properties.Results show Cs_(2)Hfl_(6),Cs_(2)SnBr_(6),Cs_(2)SnI_(6),and Cs_(2)PtBr_(6)have Young's moduli below 13 GPa,indicating flexibility.Geometric parameters explain flexibility variations with the changes of B and X site composition.Bonding characteristic exploration reveals the influence of B and X site electronegativity on mechanical strength.Cs_(2)SnBr_(6)and Cs_(2)PtBr_(6)are suitable for solar cells,while Cs_(2)HfI_(6)and Cs_(2)TiCl_(6)show potential for semi-transparent solar cells.Optical property calculations highlight the high light absorption coefficients of up to 3.5×10^(5) cm^(-1)for Cs_(2)HfI_(6)and Cs_(2)TiCl_(6).Solar cell simulation shows Cs_(2)PtBr_(6)achieves 22.4%of conversion effciency.Cs_(2)ZrCl_(6)holds promise for ionizing radiation detection with its 3.68 eV bandgap and high absorption coefficient.Vacancy-ordered double perovskites offer superior flexibility,providing valuable insights for designing stable and flexible devices.This understanding enhances the development of functional devices based on these perovskites,especially for applications requiring high stability and flexibility.展开更多
Passive intermodulation(PIM)in communication systems is an unwanted interference caused by weak nonlinear currentvoltage characteristics of radio frequency(RF)passive components.Characterization of PIM is important fo...Passive intermodulation(PIM)in communication systems is an unwanted interference caused by weak nonlinear currentvoltage characteristics of radio frequency(RF)passive components.Characterization of PIM is important for both the study of PIM mechanisms and the location/suppression of PIM sources.PIM probes,made of open-ended coaxial transmission lines,have almost the same coupling strength to carriers and PIM products,and are usually used for near-field PIM characterization.Namely,it doesn’t have any filtering capability.Therefore,it cannot stop the carrier power from entering into PIM tester’s receiver,which may trigger active intermodulation of the receiver and degrade the PIM tester’s performance.To overcome this drawback,a passive filtering coaxial probe is proposed here.Compared with existing passive coaxial PIM probes,it has stronger coupling strength for PIM products than for carriers.Thus,the probe itself can block part of the carrier power entering into the PIM tester’s receiver.This advantage helps improve PIM tester’s overall performance.Both theoretical analysis and experiments are conducted for demonstration.The proposed probe brings more possibility to PIM characterization.展开更多
A control strategy of repetitive control without inductorance decoupling was proposed to address the problem of high total harmonic distortion(THD)rate of the network-side current caused by the reduced stability of th...A control strategy of repetitive control without inductorance decoupling was proposed to address the problem of high total harmonic distortion(THD)rate of the network-side current caused by the reduced stability of the rectifier module of the DC charging pile under weak grid as well as the dead zone and nonlinearity of switching devices during charging.Firstly,the parallel repetitive control was constructed in the inner current loop,and the proportional-integral(PI)+repetitive controller based on parallel structure was designed.For system compensation,a second-order low-pass filter was selected to correct the system,and the network-side current harmonics were actively suppressed without increasing the filtering device,which effectively improves the quality of grid-connected current.Secondly,based on the synthetic vector method,the controller parameters were designed to realize the elimination of main pole by establishing two synchronous rotation coordinate system vector differential equations,so as to realize the inductanceless decoupling to cope with the influence of network-side inductance fluctuation on the stability of the control system under weak grid.By theoretical analysis and simulation,the proposed control strategy was embedded into the self-developed digital signal processor for the rectifier module of DC charging pile,simulated dynamic and steady-state operation experiments were conducted,and comparative analysis was performed to prove the feasibility of the proposed control strategy.展开更多
In complex industrial scenes,it is difficult to acquire high-precision non-cooperative target pose under monocular visual servo control.This paper presents a new method of target extraction and high-precision edge fit...In complex industrial scenes,it is difficult to acquire high-precision non-cooperative target pose under monocular visual servo control.This paper presents a new method of target extraction and high-precision edge fitting for the wheel of the sintering trolley in steel production,which fuses multiple target extraction algorithms adapting to the working environment of the target.Firstly,based on obvious difference between the pixels of the target image and the non-target image in the gray histogram,these pixels were classified and then segmented in intraclass,removing interference factors and remaining the target image.Then,multiple segmentation results were merged and a final target image was obtained after small connected regions were eliminated.In the edge fitting stage,the edge fitting method with best-circumscribed rectangle was proposed to accurately fit the circular target edge.Finally,PnP algorithm was adopted for pose measurement of the target.The experimental results showed that the average estimation error of pose angleγwith respect to the z-axis rotation was 0.2346°,the average measurement error of pose angleαwith respect to the x-axis rotation was 0.1703°,and the average measurement error of pose angle β with respect to the y-axis rotation was 0.2275°.The proposed method has practical application value.展开更多
Aeroengines,often regarded as the heart of aircraft,are crucial for flight safety and performance.Comprehensive performance evaluation of aeroengines supports Prognostics and Health Management(PHM)and aeroengine digit...Aeroengines,often regarded as the heart of aircraft,are crucial for flight safety and performance.Comprehensive performance evaluation of aeroengines supports Prognostics and Health Management(PHM)and aeroengine digital engineering.Due to their highly integrated nature,aeroengines present challenges in performance evaluation because their test-run data are high-dimensional,large-scale,and exhibit strong nonlinear correlations among test indicators.To solve this problem,this study proposes a unified framework of the comprehensive performance evaluation of aeroengines to assess performance objectively and globally.Specifically,the network model and the dynamics model of aeroengine performance are constructed driven by test-run data,which can explain the patterns of system state changes and the internal relationship,and depict the system accurately.Based on that,three perturbations in the model are used to simulate three fault modes of aeroengines.Moreover,the comprehensive performance evaluation indexes of aeroengines are proposed to evaluate the performance dynamically from two dimensions,the coupling performance and the activity performance.Thirteen test-run qualified and four test-run failed aeroengines are used to validate and establish the qualified ranges.The results demonstrate that the comprehensive evaluation indexes can distinguish test-run qualified and test-run failed aeroengines.By changing the dynamic parameters,the comprehensive performance under any thrust and inlet guide vanes(IGV)angle can be estimated,broadening the test-run scenarios beyond a few typical states.This novel approach offers significant advancements for the comprehensive performance evaluation and management of aeroengines,paving the way for future PHM and aeroengine digital engineering developments.展开更多
In order to analyze the effect of voltage during micro-arc oxidation(MAO)on corrosion and wear properties of Ti6Al4V(TC4),the MAO technology was employed to treat TC4 samples fabricated by selective electron beam melt...In order to analyze the effect of voltage during micro-arc oxidation(MAO)on corrosion and wear properties of Ti6Al4V(TC4),the MAO technology was employed to treat TC4 samples fabricated by selective electron beam melting(SEBM)at the voltages of 400,420 and 450 V.The results show that the metastable anatase phase gradually transforms to rutile phase with oxidation time and temperature increasing.The surface morphology of coating contains numerous micropores with uniform size distribution.Cracks and pores over 10μm are found on MAO-TC4 sample with applied voltage of 450 V.The thickness of MAO coating is positively correlated with the voltage.The corrosion resistance and wear resistance are related to phase composition,micropore size distribution on the surface and film thickness.When the voltage is 420 V,the coating shows the smallest corrosion current density(0.960×10^-7 A/cm^2)and the largest resistance(7.17×10^5Ω·cm^2).Under the same load condition,the coating exhibits larger friction coefficient and wear loss than the TC4 substrate.With the increase of voltage,the wear mechanism of the coating changes from abrasive wear to adhesive wear,and the adhesive wear is intensified at applied voltage of 450 V,with a maximum friction coefficient of 0.821.展开更多
This letter solves an open question of origami paper spring risen by Yoneda et al.(Phys.Rev.E 2019).By using both dimensional analysis and data fitting,an universal scaling law of a paper spring is formulated.The scal...This letter solves an open question of origami paper spring risen by Yoneda et al.(Phys.Rev.E 2019).By using both dimensional analysis and data fitting,an universal scaling law of a paper spring is formulated.The scaling law shows that origami spring force obeys power square law of spring extension,however strong nonlinear to the total twist angle.The study has also successfully generalized the scaling law from the Poisson ratio 0.3 to an arbitrary Poisson's ratio with the help of dimensional analysis.展开更多
Hypobaric hypoxia is the main environmental feature of the Tibetan plateau which would influence the efficiency of human metabolic heat production and the ability of thermal regulation.In order to understand the influ...Hypobaric hypoxia is the main environmental feature of the Tibetan plateau which would influence the efficiency of human metabolic heat production and the ability of thermal regulation.In order to understand the influence of the hypoxic environment on the plateau on the thermal comfort of short-term sojourners in Tibet,China,oxygen generators were used to create oxygen-enriched environments,and physiological and psychological reactions of subjects were compared under different oxygen partial pressures(p_(O_(2)))and air temperatures(t_(a)).The results showed that subjects’thermal sensation,thermal comfort and mean skin temperature decreased with a decrease in the oxygen partial pressure.When t_(a)=17℃,the influence of oxygen partial pressure was more pronounced,compared to p_(O_(2))=16.4 kPa,the thermal sensation of subjects under p_(O_(2))=13.7 kPa decreased by 33%.The rate of subjects feeling comfortable decreased by 25%,and the mean skin temperature decreased by 0.7℃.The hypoxic environment of the plateau exacerbates human discomfort.Therefore,it is necessary to fully understand the actual thermal requirements of sojourners in Tibet,China.The results of this study would have implications for a better understanding of thermal comfort characteristics in the hypoxia environment in plateau.展开更多
The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining ...The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining fault information.Hydraulic system is characterized by strong noise interference,which leads to low signal-to-noise ratio(SNR)of detection signals.Therefore,it is necessary to dig deep into the system operating state information carried by pressure signals.Firstly,based on flow loss mechanism of the plunger pump,the mapping relationship between flow pulsation and pressure pulsation is analyzed.After that,the pressure signal is filtered and reconstructed based on standard Gabor transform.Finally,according to the time-domain waveform morphology of pressure signal,four characteristic indicators are proposed to analyze the characteristics of pressure fluctuations under different working conditions.The experimental results show that the standard Gabor transform can accurately extract high-order harmonics and phase frequencies of the signal.The reconstructed time-domain waveform of pressure pulsation of the axial piston pump contains a wealth of operating status information,and the characteristics of pulsation changes under various working conditions can provide a new theoretical basis and a method support for fault diagnosis and health assessment of hydraulic pumps,motors and key components.展开更多
The galvanic interaction of arsenopyrite−magnetite in acidic culture medium was investigated by electrochemical measurements,X-ray photoelectron spectroscopy characterization and leaching experiments.The results indic...The galvanic interaction of arsenopyrite−magnetite in acidic culture medium was investigated by electrochemical measurements,X-ray photoelectron spectroscopy characterization and leaching experiments.The results indicated that the rest potential of magnetite was 321 mV,which was more anodic than 223 mV of arsenopyrite,and the galvanic current was 7.40μA,verifying the existence of the galvanic interaction between arsenopyrite and magnetite.The galvanic potential and polarization curves suggested that the redox behaviors of arsenopyrite dominated the overall galvanic interaction.The galvanic interaction enhanced the electrochemical dissolution of arsenopyrite with the generation of more oxidation products(S^(0),SO_(3)^(2−),SO_(4)^(2−)and AsO_(3)^(3−)) on arsenopyrite and an increase in the chemical reactivity of the surface.Leaching experiments of 6 days showed that the presence of magnetite improved the arsenic release from arsenopyrite by 30 mg/L,and further confirmed the enhanced oxidation of arsenopyrite when coupled with magnetite.展开更多
In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogene...In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogeneous, semi-infinite isotropic medium. A comparison was made between model test results and the obtained solutions to show their validity. The calculation results indicate that the horizontal displacement and bending moment of the pile increase with increases of the axial and lateral loads. The maximum horizontal displacement and bending moment decrease by 37.9% and 13.9%, respectively, when the elastic modulus of soil increases from 4 MPa to 20 MPa. The Poisson ratio of soil plays a marginal role in pile responses. There is a critical pile length under the ground, beyond which the pile behaves as though it was infinitely long. The presented solutions can make allowance for the continuous nature of soil, and if condition permits, they can approach exact ones.展开更多
The exact similarity solutions of two dimensional laminar boundary layer were obtained by Blasius in 1908,however,for two dimensional turbulent boundary layers,no Blasius type similarity solutions(special exact soluti...The exact similarity solutions of two dimensional laminar boundary layer were obtained by Blasius in 1908,however,for two dimensional turbulent boundary layers,no Blasius type similarity solutions(special exact solutions)have ever been found.In the light of Blasius’pioneer works,we extend Blasius similarity transformation to the two dimensional turbulent boundary layers,and for a special case of flow modelled by Prandtl mixing-length,we successfully transform the two dimensional turbulent boundary layers partial differential equations into a single ordinary differential equation.The ordinary differential equation is numerically solved and some useful quantities are produced.For numerical calculations,a complete Maple code is provided.展开更多
The development of wearable electronic systems has generated increasing demand for flexible power sources.Alkaline zinc(Zn)-based batteries,as one of the most mature energy storage technologies,have been considered as...The development of wearable electronic systems has generated increasing demand for flexible power sources.Alkaline zinc(Zn)-based batteries,as one of the most mature energy storage technologies,have been considered as a promising power source owing to their exceptional safety,low costs,and outstanding electrochemical performance.However,the conventional alkaline Zn-based battery systems face many challenges associated with electrodes and electrolytes,causing low capacity,poor cycle life,and inferior mechanical performance.Recent advances in materials and structure design have enabled the revisitation of the alkaline Zn-based battery technology for applications in flexible electronics.Herein,we summarize the up-to-date works in flexible alkaline Zn-based batteries and analyze the strategies employed to improve battery performance.Firstly,we introduce the three most reported cathode materials(including Ag-based,Ni-based,and Co-based materials)for flexible alkaline Zn-based batteries.Then,challenges and modifications in battery anodes are investigated.Thirdly,the recently advanced gel electrolytes are introduced from their properties,functions as well as advanced fabrications.Finally,recent works and the advantages of sandwich-type,fiber-type and thin film-type flexible batteries are summarized and compared.This review provides insights and guidance for the design of high-performance flexible Zn-based batteries for next-generation electronics.展开更多
The hydrolysate of waste sludge was used as the feedstock of biodiesel production,and its technological feasibility was investigated.Waste sludge,collected from No.3 Municipal Wastewater Treatment Plant of Xi’an,was ...The hydrolysate of waste sludge was used as the feedstock of biodiesel production,and its technological feasibility was investigated.Waste sludge,collected from No.3 Municipal Wastewater Treatment Plant of Xi’an,was hydrolyzed in two parallel reactors firstly.Yeast was added into one reactor for bioaugmentation,and the other reactor without yeast was used as a control.Then an acid-catalyzed in situ esterification process was carried out to convert the hydrolysate to biodiesel.The results of hydrolysis showed that the reactor bioaugmented with yeast could promote hydrolysis compared with the control one because of an obvious variance in total suspended solid(TSS),volatile suspended solid(VSS)and soluble chemical oxygen demand(SCOD).Furthermore,gas chromatography(GC)analysis exhibited that the total volatile fatty acid(VFA)was low in the hydrolysate of bioaugmentation reactor;however,its yield of the fatty acid methyl esters(FAMEs)by in situ esterification was obviously higher when compared with the control one.Therefore,it may be inferred that the hydrolysate of bioaugmentation was mainly inclined to longer-chain fatty acid rather than to VFA.Anyway,an FAMEs yield of 9.24%(wt%)from dried sludge was attained after the 12-d bioaugmentation hydrolysis and succedent esterification.This value was not only higher than that of the control one but also higher than that reported in previous literature.The above results illuminated that it was feasible to produce biodiesel from the bioaugmented hydrolysate of waste sludge.展开更多
The paper introduces a new type of green building which suits for the construction of rural dwellings in Xinjiang, China. Results of the shaking table test on building model show that the single-layer gypsum-adobe str...The paper introduces a new type of green building which suits for the construction of rural dwellings in Xinjiang, China. Results of the shaking table test on building model show that the single-layer gypsum-adobe structure has better seismic performance. And it also analyzes the construction features and engineering practice, which means that it is significant to extend this type of building to the drier regions in China.展开更多
Based on the rational classification and screening of the literature related to the transformation of urban villages in China,this paper studied the research framework of the architectural space field in the study of ...Based on the rational classification and screening of the literature related to the transformation of urban villages in China,this paper studied the research framework of the architectural space field in the study of urban village transformation,and analyzed the research status of architectural spaces and users in the process of urban village transformation,proposed four research contents of urban village transformation,namely,promoting space rights for all types of people to live on an equal footing,paying attention to the renewal and rejuvenation of urban areas,attaching importance to the technical methods of space construction,and ensuring flexible and diverse space construction methods,and summed up the necessity of carrying out research on urban village transformation in the field of architectural space construction.展开更多
Magnesia-chrome refractories are appropriate to work under cyclic temperatures or atmospheric conditions because some oxides of chrome ore readily release oxygen(are reduced)upon heating and pick up oxygen(are oxidize...Magnesia-chrome refractories are appropriate to work under cyclic temperatures or atmospheric conditions because some oxides of chrome ore readily release oxygen(are reduced)upon heating and pick up oxygen(are oxidized)upon cooling or upon changing the atmosphere.They have been ideal lining materials for RH degassers for many years,despite challenging of Cr^(6+) disposal issue after using.The varieties of magnesia-chrome refractories depend on their raw materials and burning temperatures,which could be well demonstrated by their microstructures.But Indian chrome concentrate cannot be directly used in the production of magnesia-chrome bricks because of reducing sintering density.Silicate bonded magnesia-chrome bricks are produced with low purity magnesia after burning at relatively lower temperatures,resulting in liquid film forming as silicate bond around chrome ore particles.Direct bonded and rebonded fused-grains magnesia-chrome refractories are made of high purity magnesia or fused magnesia-chrome grains,forming euhedral and intergranular secondary chromite spinels as the main feature.The amount of secondary spinel increases with the rising burning temperature,leading to increasing hot modulus of rupture and overall hot properties as well.It is important to burn magnesia-chrome bricks under weakly reducing atmosphere.The oxygen content of burning atmosphere from 800℃ to 1650℃ would better controlled below 0.5%to increase the burnt strength and to avoid inner cracks and loose bonding of magnesia-chrome bricks,while the atmosphere contains 3%-6%O_(2) under most economical firing condition.展开更多
China’s urbanization development has entered the“second half”,which is at a critical stage of transition from the middle stages to the mature stage.The metropolitan area formed by the mega-city radiating the develo...China’s urbanization development has entered the“second half”,which is at a critical stage of transition from the middle stages to the mature stage.The metropolitan area formed by the mega-city radiating the development of surrounding cities and counties is an important spatial carrier of urbanization.The rural characteristic industry is the main path to promote regional economic development and urban-rural integration in the metropolitan area.Exploring the development characteristics of rural characteristic industries in the metropolitan area has important theoretical and practical significance for promoting the effective connection between urban-rural integration and rural revitalization of the metropolitan area and improving the development quality of the metropolitan area.Take the Xi’an metropolitan area as an example and adopt kernel density analysis and other methods to reveal the spatial differentiation rules of rural characteristic industries.On this basis,the three-dimensional development strategy of“industry-spatial-institutional”for the development of the rural characteristic industry is proposed,to provide theoretical reference for the development of rural characteristic industry in metropolitan areas.展开更多
基金National Natural Science Foundation of China (No.52202046)Natural Science Foundation of Shaanxi Province (No.2021JQ-034)。
文摘Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial Coulombic efficiency (ICE) due to severe structural degradation caused by irreversible O release.Herein,we introduce a three-in-one strategy of increasing Ni and Mn content,along with Li/Ni disordering and TM–O covalency regulation to boost cationic and anionic redox activity simultaneously and thus enhance the electrochemical activity of LLOs.The target material,Li_(1.2)Ni_(0.168)Mn_(0.558)Co_(0.074)O_(2)(L1),exhibits an improved ICE of 87.2%and specific capacity of 293.2 mA h g^(-1)and minimal voltage decay of less than 0.53 m V cycle-1over 300 cycles at 1C,compared to Li_(1.2)Ni_(0.13)Mn_(0.54)Co_(0.13)O_(2)(Ls)(274.4 mA h g^(-1)for initial capacity,73.8%for ICE and voltage decay of 0.84 mV/cycle over 300 cycles at 1C).Theoretical calculations reveal that the density of states (DOS) area near the Fermi energy level for L1 is larger than that of Ls,indicating higher anionic and cationic redox reactivity than Ls.Moreover,L1 exhibits increased O-vacancy formation energy due to higher Li/Ni disordering of 4.76%(quantified by X-ray diffraction Rietveld refinement) and enhanced TM–O covalency,making lattice O release more difficult and thus improving electrochemical stability.The increased Li/Ni disordering also leads to more Ni^(2+)presence in the Li layer,which acts as a pillar during Li+de-embedding,improving structural stability.This research not only presents a viable approach to designing low-Co LLOs with enhanced capacity and ICE but also contributes significantly to the fundamental understanding of structural regulation in high-performance LIB cathodes.
基金National Natural Science Foundation of China(21676209)Natural Science Basic Research Program of Shaanxi(2022JQ-328)Postdoctoral Research Foundation of the Xi’an University of Architecture and Technology(19603210120).
文摘Excessive emissions of nitrogen oxides from flue gas have imposed various detrimental impacts on environment,and the development of deNO_(x) catalysts with low-cost and high performance is an urgent requirement.Iron oxide-based material has been explored for promising deNO_(x) catalysts.However,the unsatisfactory low-temperature activity limits their practical applications.In this study,a series of excellent low-temperature denitrification catalysts(Ha-FeO_(x)/yZS)were prepared by acid treatment of zinc slag,and the mass ratios of Fe to impure ions was regulated by adjusting the acid concentrations.Ha-FeO_(x)/yZS showed high denitrification performance(>90%)in the range of 180–300℃,and the optimal NO conversion and N2 selectivity were higher than 95%at 250℃.Among them,the Ha-FeO_(x)/2ZS synthesized with 2 mol/L HNO3 exhibited the widest temperature window(175–350℃).The excellent denitrification performance of Ha-FeO_(x)/yZS was mainly attributed to the strong interaction between Fe and impurity ions to inhibit the growth of crystals,making Ha-FeO_(x)/yZS with amorphous structure,nice fine particles,large specific surface area,more surface acid sites and high chemisorbed oxygen.The in-situ DRIFT experiments confirmed that the SCR reaction on the Ha-FeO_(x)/yZS followed both Langmuir-Hinshelwood(L-H)mechanism and Eley-Rideal(E-R)mechanism.The present work proposed a high value-added method for the preparation of cost-effective catalysts from zinc slag,which showed a promising application prospect in NO_(x) removal by selective catalytic reduction with ammonia.
基金supported by the National Natural Science Foundation of China(62305261,62305262)the Natural Science Foundation of Shaanxi Province(2024JC-YBMS-021,2024JC-YBMS-788,2023-JC-YB-065,2023-JC-QN-0693,2022JQ-652)+1 种基金the Xi’an Science and Technology Bureau of University Service Enterprise Project(23GXFW0043)the Cross disciplinary Research and Cultivation Project of Xi’an University of Architecture and Technology(2023JCPY-17)。
文摘As interest in double perovskites is growing,especially in applications like photovoltaic devices,understanding their mechanical properties is vital for device durability.Despite extensive exploration of structure and optical properties,research on mechanical aspects is limited.This article builds a vacancyordered double perovskite model,employing first-principles calculations to analyze mechanical,bonding,electronic,and optical properties.Results show Cs_(2)Hfl_(6),Cs_(2)SnBr_(6),Cs_(2)SnI_(6),and Cs_(2)PtBr_(6)have Young's moduli below 13 GPa,indicating flexibility.Geometric parameters explain flexibility variations with the changes of B and X site composition.Bonding characteristic exploration reveals the influence of B and X site electronegativity on mechanical strength.Cs_(2)SnBr_(6)and Cs_(2)PtBr_(6)are suitable for solar cells,while Cs_(2)HfI_(6)and Cs_(2)TiCl_(6)show potential for semi-transparent solar cells.Optical property calculations highlight the high light absorption coefficients of up to 3.5×10^(5) cm^(-1)for Cs_(2)HfI_(6)and Cs_(2)TiCl_(6).Solar cell simulation shows Cs_(2)PtBr_(6)achieves 22.4%of conversion effciency.Cs_(2)ZrCl_(6)holds promise for ionizing radiation detection with its 3.68 eV bandgap and high absorption coefficient.Vacancy-ordered double perovskites offer superior flexibility,providing valuable insights for designing stable and flexible devices.This understanding enhances the development of functional devices based on these perovskites,especially for applications requiring high stability and flexibility.
文摘Passive intermodulation(PIM)in communication systems is an unwanted interference caused by weak nonlinear currentvoltage characteristics of radio frequency(RF)passive components.Characterization of PIM is important for both the study of PIM mechanisms and the location/suppression of PIM sources.PIM probes,made of open-ended coaxial transmission lines,have almost the same coupling strength to carriers and PIM products,and are usually used for near-field PIM characterization.Namely,it doesn’t have any filtering capability.Therefore,it cannot stop the carrier power from entering into PIM tester’s receiver,which may trigger active intermodulation of the receiver and degrade the PIM tester’s performance.To overcome this drawback,a passive filtering coaxial probe is proposed here.Compared with existing passive coaxial PIM probes,it has stronger coupling strength for PIM products than for carriers.Thus,the probe itself can block part of the carrier power entering into the PIM tester’s receiver.This advantage helps improve PIM tester’s overall performance.Both theoretical analysis and experiments are conducted for demonstration.The proposed probe brings more possibility to PIM characterization.
基金supported by National Natural Science Foundation of China(No.61903291)Shaanxi Province Key R&D Program(No.2022GY-134)。
文摘A control strategy of repetitive control without inductorance decoupling was proposed to address the problem of high total harmonic distortion(THD)rate of the network-side current caused by the reduced stability of the rectifier module of the DC charging pile under weak grid as well as the dead zone and nonlinearity of switching devices during charging.Firstly,the parallel repetitive control was constructed in the inner current loop,and the proportional-integral(PI)+repetitive controller based on parallel structure was designed.For system compensation,a second-order low-pass filter was selected to correct the system,and the network-side current harmonics were actively suppressed without increasing the filtering device,which effectively improves the quality of grid-connected current.Secondly,based on the synthetic vector method,the controller parameters were designed to realize the elimination of main pole by establishing two synchronous rotation coordinate system vector differential equations,so as to realize the inductanceless decoupling to cope with the influence of network-side inductance fluctuation on the stability of the control system under weak grid.By theoretical analysis and simulation,the proposed control strategy was embedded into the self-developed digital signal processor for the rectifier module of DC charging pile,simulated dynamic and steady-state operation experiments were conducted,and comparative analysis was performed to prove the feasibility of the proposed control strategy.
基金supported by Key Research and Development Projects in Shaanxi Province (No. 2021GY-265)Xi’an University Talent Service Enterprise Project (No.2020KJRC0049)。
文摘In complex industrial scenes,it is difficult to acquire high-precision non-cooperative target pose under monocular visual servo control.This paper presents a new method of target extraction and high-precision edge fitting for the wheel of the sintering trolley in steel production,which fuses multiple target extraction algorithms adapting to the working environment of the target.Firstly,based on obvious difference between the pixels of the target image and the non-target image in the gray histogram,these pixels were classified and then segmented in intraclass,removing interference factors and remaining the target image.Then,multiple segmentation results were merged and a final target image was obtained after small connected regions were eliminated.In the edge fitting stage,the edge fitting method with best-circumscribed rectangle was proposed to accurately fit the circular target edge.Finally,PnP algorithm was adopted for pose measurement of the target.The experimental results showed that the average estimation error of pose angleγwith respect to the z-axis rotation was 0.2346°,the average measurement error of pose angleαwith respect to the x-axis rotation was 0.1703°,and the average measurement error of pose angle β with respect to the y-axis rotation was 0.2275°.The proposed method has practical application value.
基金supported by the National Natural Science Foundation of China(72231008,72171193,and 72071153)the Science and Technology Innovation Group Program of Shaanxi Province(2024RS-CXTD-28)the Open Fund of Intelligent Control Laboratory(ICL-2023-0304).
文摘Aeroengines,often regarded as the heart of aircraft,are crucial for flight safety and performance.Comprehensive performance evaluation of aeroengines supports Prognostics and Health Management(PHM)and aeroengine digital engineering.Due to their highly integrated nature,aeroengines present challenges in performance evaluation because their test-run data are high-dimensional,large-scale,and exhibit strong nonlinear correlations among test indicators.To solve this problem,this study proposes a unified framework of the comprehensive performance evaluation of aeroengines to assess performance objectively and globally.Specifically,the network model and the dynamics model of aeroengine performance are constructed driven by test-run data,which can explain the patterns of system state changes and the internal relationship,and depict the system accurately.Based on that,three perturbations in the model are used to simulate three fault modes of aeroengines.Moreover,the comprehensive performance evaluation indexes of aeroengines are proposed to evaluate the performance dynamically from two dimensions,the coupling performance and the activity performance.Thirteen test-run qualified and four test-run failed aeroengines are used to validate and establish the qualified ranges.The results demonstrate that the comprehensive evaluation indexes can distinguish test-run qualified and test-run failed aeroengines.By changing the dynamic parameters,the comprehensive performance under any thrust and inlet guide vanes(IGV)angle can be estimated,broadening the test-run scenarios beyond a few typical states.This novel approach offers significant advancements for the comprehensive performance evaluation and management of aeroengines,paving the way for future PHM and aeroengine digital engineering developments.
基金Projects(51504191,51671152,51874225)supported by the National Natural Science Foundation of ChinaProject supported by the Fund of State Key Laboratory of Porous Metal Materials,China。
文摘In order to analyze the effect of voltage during micro-arc oxidation(MAO)on corrosion and wear properties of Ti6Al4V(TC4),the MAO technology was employed to treat TC4 samples fabricated by selective electron beam melting(SEBM)at the voltages of 400,420 and 450 V.The results show that the metastable anatase phase gradually transforms to rutile phase with oxidation time and temperature increasing.The surface morphology of coating contains numerous micropores with uniform size distribution.Cracks and pores over 10μm are found on MAO-TC4 sample with applied voltage of 450 V.The thickness of MAO coating is positively correlated with the voltage.The corrosion resistance and wear resistance are related to phase composition,micropore size distribution on the surface and film thickness.When the voltage is 420 V,the coating shows the smallest corrosion current density(0.960×10^-7 A/cm^2)and the largest resistance(7.17×10^5Ω·cm^2).Under the same load condition,the coating exhibits larger friction coefficient and wear loss than the TC4 substrate.With the increase of voltage,the wear mechanism of the coating changes from abrasive wear to adhesive wear,and the adhesive wear is intensified at applied voltage of 450 V,with a maximum friction coefficient of 0.821.
基金the financial supports from Xi’an University of Architecture and Technology
文摘This letter solves an open question of origami paper spring risen by Yoneda et al.(Phys.Rev.E 2019).By using both dimensional analysis and data fitting,an universal scaling law of a paper spring is formulated.The scaling law shows that origami spring force obeys power square law of spring extension,however strong nonlinear to the total twist angle.The study has also successfully generalized the scaling law from the Poisson ratio 0.3 to an arbitrary Poisson's ratio with the help of dimensional analysis.
基金Project(U20A20311)supported by the State Key Program of National Natural Science Foundation of ChinaProject(52008329)supported by the National Natural Science Foundation of ChinaProject(2018BSHYDZZ14)supported by the Postdoctoral Research Foundation of Shaanxi Province,China。
文摘Hypobaric hypoxia is the main environmental feature of the Tibetan plateau which would influence the efficiency of human metabolic heat production and the ability of thermal regulation.In order to understand the influence of the hypoxic environment on the plateau on the thermal comfort of short-term sojourners in Tibet,China,oxygen generators were used to create oxygen-enriched environments,and physiological and psychological reactions of subjects were compared under different oxygen partial pressures(p_(O_(2)))and air temperatures(t_(a)).The results showed that subjects’thermal sensation,thermal comfort and mean skin temperature decreased with a decrease in the oxygen partial pressure.When t_(a)=17℃,the influence of oxygen partial pressure was more pronounced,compared to p_(O_(2))=16.4 kPa,the thermal sensation of subjects under p_(O_(2))=13.7 kPa decreased by 33%.The rate of subjects feeling comfortable decreased by 25%,and the mean skin temperature decreased by 0.7℃.The hypoxic environment of the plateau exacerbates human discomfort.Therefore,it is necessary to fully understand the actual thermal requirements of sojourners in Tibet,China.The results of this study would have implications for a better understanding of thermal comfort characteristics in the hypoxia environment in plateau.
基金National Natural Science Foundation of China(No.51675399)。
文摘The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining fault information.Hydraulic system is characterized by strong noise interference,which leads to low signal-to-noise ratio(SNR)of detection signals.Therefore,it is necessary to dig deep into the system operating state information carried by pressure signals.Firstly,based on flow loss mechanism of the plunger pump,the mapping relationship between flow pulsation and pressure pulsation is analyzed.After that,the pressure signal is filtered and reconstructed based on standard Gabor transform.Finally,according to the time-domain waveform morphology of pressure signal,four characteristic indicators are proposed to analyze the characteristics of pressure fluctuations under different working conditions.The experimental results show that the standard Gabor transform can accurately extract high-order harmonics and phase frequencies of the signal.The reconstructed time-domain waveform of pressure pulsation of the axial piston pump contains a wealth of operating status information,and the characteristics of pulsation changes under various working conditions can provide a new theoretical basis and a method support for fault diagnosis and health assessment of hydraulic pumps,motors and key components.
基金the Natural Science Basic Research Program of Shaanxi,China(No.2020JQ-666)the National Natural Science Foundation of China(Nos.52004198,51934009).
文摘The galvanic interaction of arsenopyrite−magnetite in acidic culture medium was investigated by electrochemical measurements,X-ray photoelectron spectroscopy characterization and leaching experiments.The results indicated that the rest potential of magnetite was 321 mV,which was more anodic than 223 mV of arsenopyrite,and the galvanic current was 7.40μA,verifying the existence of the galvanic interaction between arsenopyrite and magnetite.The galvanic potential and polarization curves suggested that the redox behaviors of arsenopyrite dominated the overall galvanic interaction.The galvanic interaction enhanced the electrochemical dissolution of arsenopyrite with the generation of more oxidation products(S^(0),SO_(3)^(2−),SO_(4)^(2−)and AsO_(3)^(3−)) on arsenopyrite and an increase in the chemical reactivity of the surface.Leaching experiments of 6 days showed that the presence of magnetite improved the arsenic release from arsenopyrite by 30 mg/L,and further confirmed the enhanced oxidation of arsenopyrite when coupled with magnetite.
基金Projects(50708093,51208409)supported by the National Natural Science Foundation of ChinaProject(DB01129)supported by the Talent Foundation of Xi’an University of Architecture and Technology,China
文摘In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogeneous, semi-infinite isotropic medium. A comparison was made between model test results and the obtained solutions to show their validity. The calculation results indicate that the horizontal displacement and bending moment of the pile increase with increases of the axial and lateral loads. The maximum horizontal displacement and bending moment decrease by 37.9% and 13.9%, respectively, when the elastic modulus of soil increases from 4 MPa to 20 MPa. The Poisson ratio of soil plays a marginal role in pile responses. There is a critical pile length under the ground, beyond which the pile behaves as though it was infinitely long. The presented solutions can make allowance for the continuous nature of soil, and if condition permits, they can approach exact ones.
基金Xi’an University of Architecture and Technology(Grant no.002/2040221134).
文摘The exact similarity solutions of two dimensional laminar boundary layer were obtained by Blasius in 1908,however,for two dimensional turbulent boundary layers,no Blasius type similarity solutions(special exact solutions)have ever been found.In the light of Blasius’pioneer works,we extend Blasius similarity transformation to the two dimensional turbulent boundary layers,and for a special case of flow modelled by Prandtl mixing-length,we successfully transform the two dimensional turbulent boundary layers partial differential equations into a single ordinary differential equation.The ordinary differential equation is numerically solved and some useful quantities are produced.For numerical calculations,a complete Maple code is provided.
基金financial support from the Australian Research Council(LP1900113)。
文摘The development of wearable electronic systems has generated increasing demand for flexible power sources.Alkaline zinc(Zn)-based batteries,as one of the most mature energy storage technologies,have been considered as a promising power source owing to their exceptional safety,low costs,and outstanding electrochemical performance.However,the conventional alkaline Zn-based battery systems face many challenges associated with electrodes and electrolytes,causing low capacity,poor cycle life,and inferior mechanical performance.Recent advances in materials and structure design have enabled the revisitation of the alkaline Zn-based battery technology for applications in flexible electronics.Herein,we summarize the up-to-date works in flexible alkaline Zn-based batteries and analyze the strategies employed to improve battery performance.Firstly,we introduce the three most reported cathode materials(including Ag-based,Ni-based,and Co-based materials)for flexible alkaline Zn-based batteries.Then,challenges and modifications in battery anodes are investigated.Thirdly,the recently advanced gel electrolytes are introduced from their properties,functions as well as advanced fabrications.Finally,recent works and the advantages of sandwich-type,fiber-type and thin film-type flexible batteries are summarized and compared.This review provides insights and guidance for the design of high-performance flexible Zn-based batteries for next-generation electronics.
基金Supported by Excellent Project from Shaanxi Administration of Foreign Expert Affairs in 2011International Cooperation Project of Shaanxi Province(No.2011KW-34)
文摘The hydrolysate of waste sludge was used as the feedstock of biodiesel production,and its technological feasibility was investigated.Waste sludge,collected from No.3 Municipal Wastewater Treatment Plant of Xi’an,was hydrolyzed in two parallel reactors firstly.Yeast was added into one reactor for bioaugmentation,and the other reactor without yeast was used as a control.Then an acid-catalyzed in situ esterification process was carried out to convert the hydrolysate to biodiesel.The results of hydrolysis showed that the reactor bioaugmented with yeast could promote hydrolysis compared with the control one because of an obvious variance in total suspended solid(TSS),volatile suspended solid(VSS)and soluble chemical oxygen demand(SCOD).Furthermore,gas chromatography(GC)analysis exhibited that the total volatile fatty acid(VFA)was low in the hydrolysate of bioaugmentation reactor;however,its yield of the fatty acid methyl esters(FAMEs)by in situ esterification was obviously higher when compared with the control one.Therefore,it may be inferred that the hydrolysate of bioaugmentation was mainly inclined to longer-chain fatty acid rather than to VFA.Anyway,an FAMEs yield of 9.24%(wt%)from dried sludge was attained after the 12-d bioaugmentation hydrolysis and succedent esterification.This value was not only higher than that of the control one but also higher than that reported in previous literature.The above results illuminated that it was feasible to produce biodiesel from the bioaugmented hydrolysate of waste sludge.
基金Science and Technology Key Projects of the Construction Department of Xinjiang Uygur Autonomous Region
文摘The paper introduces a new type of green building which suits for the construction of rural dwellings in Xinjiang, China. Results of the shaking table test on building model show that the single-layer gypsum-adobe structure has better seismic performance. And it also analyzes the construction features and engineering practice, which means that it is significant to extend this type of building to the drier regions in China.
基金Sponsored by the National Natural Science Fund(51508436)the Cultivation Fund of Xi’an University of Science and Technology(201341)
文摘Based on the rational classification and screening of the literature related to the transformation of urban villages in China,this paper studied the research framework of the architectural space field in the study of urban village transformation,and analyzed the research status of architectural spaces and users in the process of urban village transformation,proposed four research contents of urban village transformation,namely,promoting space rights for all types of people to live on an equal footing,paying attention to the renewal and rejuvenation of urban areas,attaching importance to the technical methods of space construction,and ensuring flexible and diverse space construction methods,and summed up the necessity of carrying out research on urban village transformation in the field of architectural space construction.
文摘Magnesia-chrome refractories are appropriate to work under cyclic temperatures or atmospheric conditions because some oxides of chrome ore readily release oxygen(are reduced)upon heating and pick up oxygen(are oxidized)upon cooling or upon changing the atmosphere.They have been ideal lining materials for RH degassers for many years,despite challenging of Cr^(6+) disposal issue after using.The varieties of magnesia-chrome refractories depend on their raw materials and burning temperatures,which could be well demonstrated by their microstructures.But Indian chrome concentrate cannot be directly used in the production of magnesia-chrome bricks because of reducing sintering density.Silicate bonded magnesia-chrome bricks are produced with low purity magnesia after burning at relatively lower temperatures,resulting in liquid film forming as silicate bond around chrome ore particles.Direct bonded and rebonded fused-grains magnesia-chrome refractories are made of high purity magnesia or fused magnesia-chrome grains,forming euhedral and intergranular secondary chromite spinels as the main feature.The amount of secondary spinel increases with the rising burning temperature,leading to increasing hot modulus of rupture and overall hot properties as well.It is important to burn magnesia-chrome bricks under weakly reducing atmosphere.The oxygen content of burning atmosphere from 800℃ to 1650℃ would better controlled below 0.5%to increase the burnt strength and to avoid inner cracks and loose bonding of magnesia-chrome bricks,while the atmosphere contains 3%-6%O_(2) under most economical firing condition.
基金Key R&D Plan of China’s“Fourteenth Five Year Plan for National Economic and Social Development”,subject number:2022YFC3800101funded by the Ministry of Education,the People’s Republic of China,grant number 20JZD012Xi’an University of Architecture and Technology,grant number 2022SCHZ05.
文摘China’s urbanization development has entered the“second half”,which is at a critical stage of transition from the middle stages to the mature stage.The metropolitan area formed by the mega-city radiating the development of surrounding cities and counties is an important spatial carrier of urbanization.The rural characteristic industry is the main path to promote regional economic development and urban-rural integration in the metropolitan area.Exploring the development characteristics of rural characteristic industries in the metropolitan area has important theoretical and practical significance for promoting the effective connection between urban-rural integration and rural revitalization of the metropolitan area and improving the development quality of the metropolitan area.Take the Xi’an metropolitan area as an example and adopt kernel density analysis and other methods to reveal the spatial differentiation rules of rural characteristic industries.On this basis,the three-dimensional development strategy of“industry-spatial-institutional”for the development of the rural characteristic industry is proposed,to provide theoretical reference for the development of rural characteristic industry in metropolitan areas.
