The study of multi-dimensional expansion of urban space(MEUS) addresses the laws of urban spatial expansion from all directions and angles. Using Nanjing as an example,this paper constructs multi-temporal, urban three...The study of multi-dimensional expansion of urban space(MEUS) addresses the laws of urban spatial expansion from all directions and angles. Using Nanjing as an example,this paper constructs multi-temporal, urban three-dimensional models based on RS and GIS technology and then conducts qualitative and quantitative analysis of MEUS using plot ratio change maps and MEUS quantitative index for built-up areas. Based especially on the concept of volume growth contribution rate, this paper analyzes the characteristics of MEUS in different stages. The results show that in 2000–2004, planar expansion played the main role,the internal potential development(IPD) intensity of the urban built-up areas was relatively large, and the volume growth contribution rate was low; in 2004–2008, planar expansion accelerated, and IPD slowed down; in 2008–2012, planar expansion slowed while IPD intensity increased; the contribution rates of volume growth of urban IPD for the three periods were 22.21%, 24.51% and 73.38%, respectively. This study expands the research perspective of urban spatial expansion, and the adopted methods are instructive and meaningful for MEUS research. In addition, the results of this study will deepen the understanding of MEUS laws and help improve scientific decision-making for urban planning and urban land use management.展开更多
Succinonitrile(SN)-based polymer plastic crystal electrolytes(PPCEs)are regarded as promising candidates for lithium metal batteries but suffer from serious side reactions with Li metal.Herein,we propose a multi-dimen...Succinonitrile(SN)-based polymer plastic crystal electrolytes(PPCEs)are regarded as promising candidates for lithium metal batteries but suffer from serious side reactions with Li metal.Herein,we propose a multi-dimensional optimization strategy to alleviate the side reactions between SN and Li metal,and develop a highly stable poly-vinylethylene carbonate-based PPCE(PPCE-VEC).Moreover,we identify the intrinsic factors of multi-dimensional polymer structures on the electrolyte stability by three typical classes of polyesters.The PPCE-VEC constructed by in situ polymerization exhibits much better stability than poly-vinylene carbonate-based PPCE(PPCE-VCA)and poly-trifluoroethyl acrylate-based PPCE(PPCE-TFA),which is verified by its fewer SN-decomposition species in X-ray photoelectron spectroscopy(XPS)and outstanding full cell performance.The PPCE-VEC-enabled LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)full cell achieve 73.7%capacity retention after 1400 cycles,which outperforms PPCE-VCA-and PPCE-TFA-enabled full cells(61.9%and 46.9%).Spectral analysis and theoretical calculation reveal that the high solvation ability of the carbonyl site,flexible polymer chain,and homogeneous electrolyte phase of PPCE-VEC are favorable to maximizing competition coordination with Li^(+)to weaken the Li^(+)–SN binding and shape an anion-rich solvation structure.This optimized polymer-involved Li^(+)solvation enhances SN stability and facilitates the formation of B/F enriched solid-electrolyte interphase(SEI),thus significantly improving PPCE stability.展开更多
There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with h...There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with high thermal conductivity.Furthermore,it explores the preparation of AlN_(P)/Mg-Zn-Cu composites featuring low coefficients of thermal expansion.The stir casting method was utilized to fabricate the composites and an investigation was conducted to examine their microstructure and thermal properties.Results indicate that the addition of AlN_(P)reduces the thermal expansion coefficient while maintaining relatively high thermal conductivity.Specifically,the AlN_(P)/Mg-0.5Zn-0.5Cu composite with 30wt.%AlN_(P)achieves a thermal conductivity of 132.7 W·m^(-1)·K^(-1)and a thermal expansion coefficient of 18.5×10^(-6)K^(-1),rendering it suitable for electronic packaging applications where thermal management is critical.展开更多
In-situ enlargement of super-large-span tunnels can intensify excavation-induced unloading in the surrounding rock,increasing deformation demand and failure risk during construction.This study combines laboratory mode...In-situ enlargement of super-large-span tunnels can intensify excavation-induced unloading in the surrounding rock,increasing deformation demand and failure risk during construction.This study combines laboratory model tests with FLAC3D simulations to evaluate the stabilizing role of prestressed anchor cables and to establish an energy-balance framework for support optimization.Comparative model tests of existing and enlarged tunnel sections,with and without anchors,show that reinforcement increases load-carrying capacity,reduces displacement,and confines damage to more localized zones.The numerical simulations reproduce displacement fields,shear-strain localization,and plastic-zone evolution with good agreement against the experimental observations.The energy framework is implemented in the in-situ simulations by quantifying unloading-related energy release in the rock mass and reinforcement work contributed by the anchors,and by introducing an energy release–reinforcement ratio as a stability indicator.Parametric analyses indicate that anchor length,spacing,and prestress influence stability in a nonlinear manner,with diminishing returns once reinforcement extends beyond the mechanically dominant deformation zone.An efficient parameter window is identified that improves deformation and yielding control while avoiding unnecessary reinforcement.The results provide an energy-consistent and design-oriented basis for prestressed anchorage selection in large-span tunnel expansion.展开更多
The metallic Ni catalyst suffers from strong binding with the*CO intermediate,resulting in poisoning of the catalyst surface.It is feasible to facilitate the generation of CO by alleviating the binding strength of the...The metallic Ni catalyst suffers from strong binding with the*CO intermediate,resulting in poisoning of the catalyst surface.It is feasible to facilitate the generation of CO by alleviating the binding strength of the*CO intermediate on the Ni metal surface through a lattice expansion strategy.Here,Ni_(3)ZnC_(0.7)@C with lattice expansion was synthesized by co-doping with Zn and interstitial C through high-temperature pyrolysis.Structural characterization confirms that the lattice of Ni_(3)ZnC_(0.7)expands by 5.47%compared to Ni due to the co-doping of Zn and interstitial C.The Ni_(3)ZnC_(0.7)@C possesses excellent catalytic performance with Faradaic efficiency(FE)of CO exceeding 90%over a wide potential range from−0.8 to−1.4 V versus reversible hydrogen electrode(vs.RHE)with a peak FECO of 96.6%at−1.0 V vs.RHE.In membrane electrode assembly(MEA)testing,Ni_(3)ZnC_(0.7)@C achieves a FECO of 81.4%at the industrial-level current density of 400 mA cm^(−2).In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)and density functional theory(DFT)calculations reveal that the co-introduction of Zn and interstitial C in the Ni crystal can significantly promote the desorption of*CO intermediate,which facilitates the generation of CO.This study demonstrates a viable way for designing efficient transition metal catalysts for CO_(2)electroreduction through lattice strain engineering.展开更多
Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the...Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.展开更多
A composite anti-disturbance predictive control strategy employing a Multi-dimensional Taylor Network(MTN)is presented for unmanned systems subject to time-delay and multi-source disturbances.First,the multi-source di...A composite anti-disturbance predictive control strategy employing a Multi-dimensional Taylor Network(MTN)is presented for unmanned systems subject to time-delay and multi-source disturbances.First,the multi-source disturbances are addressed according to their specific characteristics as follows:(A)an MTN data-driven model,which is used for uncertainty description,is designed accompanied with the mechanism model to represent the unmanned systems;(B)an adaptive MTN filter is used to remove the influence of the internal disturbance;(C)an MTN disturbance observer is constructed to estimate and compensate for the influence of the external disturbance;(D)the Extended Kalman Filter(EKF)algorithm is utilized as the learning mechanism for MTNs.Second,to address the time-delay effect,a recursiveτstep-ahead MTN predictive model is designed utilizing recursive technology,aiming to mitigate the impact of time-delay,and the EKF algorithm is employed as its learning mechanism.Then,the MTN predictive control law is designed based on the quadratic performance index.By implementing the proposed composite controller to unmanned systems,simultaneous feedforward compensation and feedback suppression to the multi-source disturbances are conducted.Finally,the convergence of the MTN and the stability of the closed-loop system are established utilizing the Lyapunov theorem.Two exemplary applications of unmanned systems involving unmanned vehicle and rigid spacecraft are presented to validate the effectiveness of the proposed approach.展开更多
Global population growth and rising standards of living are the driving factors for the cropland expansion to meet increasing demands.However,there is no clear assessment of the specific losses on ecosystem services c...Global population growth and rising standards of living are the driving factors for the cropland expansion to meet increasing demands.However,there is no clear assessment of the specific losses on ecosystem services caused by China's expansion of cropland to ensure food security at the cost of losing ecological land such as forests and grasslands.This study employed the ArcGIS platform and integrated valuation of ecosystem services and tradeoffs(InVEST)model to explore the cropland expansion in China from 2000 to 2020 and its impact on ecosystem services,so as to predict the priority areas of future cropland expansion in different scenarios.The results indicated that in the past 20 years,the total area of cropland expansion in China was 17.04 million hm^(2)with 70.79% conversion from forests and grasslands.Cropland expansion has contributed to an overall improvement in the food supply services with the Northern Arid and Semi-Arid Region exhibiting an increase of 18.76×10^(6) tons,while concurrently leading to a decline in habitat quality services.The priority areas for future cropland expansion without ecological loss were found to be 1.42 million hm^(2),which only account for 9.44% of the total reclaimable land.To minimize the loss of ecosystem services,there is a need to adjust the cropland replenishment policies and provide an operational solution for global food security and ecological protection.展开更多
Increasing the hole expansion ratio is significant for developing high formability parts.Hole expansion tests were carried out on low carbon hot-rolled steel containing 0.11%Ti,0.072%Ti–0.03%Nb and 0.097%Ti–0.059%Nb...Increasing the hole expansion ratio is significant for developing high formability parts.Hole expansion tests were carried out on low carbon hot-rolled steel containing 0.11%Ti,0.072%Ti–0.03%Nb and 0.097%Ti–0.059%Nb,respectively.The effects of microstructure,texture,crack propagation behavior and second phase precipitation behavior on hole expansion ratio were investigated.The precipitation behavior of TiC and(Ti,Nb)C in austenite and ferrite in three groups of steel samples was calculated theoretically.The results showed that the hole expansion ratios of 0.11Ti,0.072Ti–0.03Nb and 0.097Ti–0.059Nb test steels were 51.73%,51.17%and 66.24%following simulated coiling at 600℃,respectively.The microstructure was mainly polygonal ferrite with a small amount of pearlite.The grain refinement of 0.097Ti–0.059Nb test steel and the low texture ratio of{110}//ND improved the hole expansion ratio.The low overall hole expansion ratio was due to the microstructure inhomogeneity.The microstructure uniformity was improved by the quenching and tempering treatment,and the hole expansion ratio of the three test steels was greatly increased.The fastest precipitation temperatures in the austenitic region of 0.11Ti,0.072Ti–0.03Nb and 0.097Ti–0.059Nb test steels were 880,860 and 830℃,while those in the ferrite region were 680,675 and 675℃,respectively.The addition of Nb element increased the volume free energy,so that the critical core size of the nucleation on the dislocation line increased,resulting in the decrease in the fastest precipitation temperature.展开更多
Negative thermal expansion(NTE)is a notable physical property where a material’s volume decreases instead of increasing when heated.The identification of NTE materials is crucial for thermal expansion control enginee...Negative thermal expansion(NTE)is a notable physical property where a material’s volume decreases instead of increasing when heated.The identification of NTE materials is crucial for thermal expansion control engineering.Most NTE materials exhibit NTE only within a narrow temperature range,restricting their applications.Achieving NTE across a broad temperature range remains a significant challenge.This study developed a novel PbTiO_(3)-based system,(1-x)PbTiO_(3–x)BiLuO_(3),incorporating rare-earth elements,using a distinctive high-pressure and high-temperature synthesis technique.We achieved NTE across a broad temperature range by coupling lattice(c/a)with ferroelectric order parameters.The incorporation of BiLuO_(3)resulted in distinctive ferroelectric characteristics,including increased tetragonality,spontaneous polarization,and NTE over a broad temperature range.NTE over an extended temperature range has been achieved in 0.95PbTiO_(3)–0.05BiLuO_(3)(■=−1.7×10^(–5)K^(−1),300–840 K)and 0.90PbTiO_(3)–0.10BiLuO_(3)(■=−1.4×10^(–5)K^(−1),300–860 K),compared to pristine PbTiO_(3)(■=−1.99×10^(–5)K^(−1),300–763 K).The improved tetragonalities and broader NTE temperature range result from the strong hybridization of Pb/Bi–O and Ti/Lu–O atoms,as demonstrated by combined experimental and theoretical analyses,including high-energy synchrotron X-ray diffraction,Raman spectroscopy,and density functional theory calculations.This study introduces a novel example of NTE over a broad temperature range,highlighting its potential as a high-performance thermal expansion compensator.Additionally,it presents an effective method for incorporating rare-earth elements to achieve NTE in PbTiO_(3)-based perovskites across a wide temperature range.展开更多
Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the de...Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the degradation behavior and failure mechanism of various overcharged states(100%SOC,105%SOC,110%SOC,and 115%SOC),multiple advanced in-situ characterization techniques(accelerating rate calorimeter,electrochemical impedance spectroscopy,ultrasonic scanning,and expansion instrument)were utilized.Additionally,re-overcharge-induced thermal runaway(TR)tests were conducted,with a specific emphasis on the evolution of the expansion force signal.Results indicated significant degradation at 110%SOC including conductivity loss,loss of lithium inventory,and loss of active material accompanied by internal gas generation.These failure behaviors slow down the expansion force rate during reovercharging,reducing the efficacy of active warnings that depend on rate thresholds of expansion force.Specifically,the warning time for 115%SOC battery is only 144 s,which is 740 s shorter than that for fresh battery,and the time to TR is advanced by 9 min.Moreover,the initial self-heating temperature(T1)is reduced by 62.4℃compared to that of fresh battery,reaching only 70.8℃.To address the low safety of overcharged batteries,a passive overcharge warning method utilizing relaxation expansion force was proposed,based on the continued gas generation after stopping charging,leading to a sustained increase in force.Compared to active methods that rely on thresholds of expansion force rate,the passive method can issue warnings 115 s earlier.By combining the passive and active warning methods,guaranteed effective overcharge warning can be issued 863-884 s before TR.This study introduces a novel perspective for enhancing the safety of batteries.展开更多
Sulfate attack-induced expansion of cement-treated aggregates in seasonally frozen regions is a well-known issue which causes continuous expansion in railway subgrades,and particularly in high-speed railways.According...Sulfate attack-induced expansion of cement-treated aggregates in seasonally frozen regions is a well-known issue which causes continuous expansion in railway subgrades,and particularly in high-speed railways.Accordingly,we investigated the influence of material proportions,the number of freeze-thaw(FT)cycles,and temperature gradients on the expansion mechanism of sulfate attack on cement-treated aggregates subjected to FT cycles.The conditions,laws,and dominant factors causing the expansion of aggregates were analyzed through swelling tests.The results indicate that under FT cycles,3%content cement-treated graded macadam only experiences slight deformation.The maximum strain of graded macadam attacked by 1%sodium sulfate content in each FT cycle is significantly larger than that of 3%content cement-treated graded macadam attacked by 1%sodium sulfate content.Using scanning electron microscopy,needle-like crystals were observed during sulfate attack of cement-treated graded macadam.Through quantitative analysis,we determined the recoverable and unrecoverable deformations of graded macadam under FT cycles.For graded macadam under sulfate attack,the expansion is mainly induced by periodic frost heave and salt expansion,as well as salt migration.For cement-treated graded macadam under sulfate attack,the expansion is mainly induced by chemical attack and salt migration.This study can serve as a reference for future research on the mechanics of sulfate attack on cement-treated aggregates that experience FT cycles,and provide theoretical support for methods that remediate the expansion induced by sulfate attack.展开更多
Minimizing the thermal expansion coefficient(TEC)mismatch between the cathode and electrolyte in solid oxide fuel cells is crucial for achieving stable,durable operation and high performance.Recently,materials with ne...Minimizing the thermal expansion coefficient(TEC)mismatch between the cathode and electrolyte in solid oxide fuel cells is crucial for achieving stable,durable operation and high performance.Recently,materials with negative thermal expansion(NTE)have at-tracted significant attention as effective additives for tailoring the thermomechanical properties of electrodes and enhancing cell durability.In this work,for the first time,single-phase NTE perovskite Sm_(0.85)Zn_(0.15)MnO_(3−δ)(SZM15)was successfully synthesized via the sol-gel method,eliminating the unwanted ZnO phase typically observed in materials obtained through the conventional solid-state reaction route.The sol-gel approach proved highly advantageous,offering low cost,robustness,excellent chemical homogeneity,precise compositional control,and high phase purity.After optimization of synthesis parameters,a negative TEC of approximately−6.5×10^(−6)K^(−1)was achieved in the 400-850℃range.SZM15 was then incorporated as an additive(10wt%-50wt%)into a SmBa0.5Sr0.5CoCuO_(5+δ)(SBSCCO)cathode to tune the thermomechanical properties with a La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.2)O_(3−δ)(LSGM)electrolyte,achieving a minimal TEC mismatch of only 1%.Notably,the SBSCCO+10wt%SZM15 composite cathode exhibited the lowest polarization resistance of 0.019Ω·cm^(2)at 900℃,showing approximately 70%lower than that of the pristine cathode.Excellent long-term stability after 100 h of operation was achieved.In addition,a high peak power density of 680 mW·cm^(−2)was achieved in a Ni-YSZ(yttria-stabilized zirconia)|YSZ|Ce_(0.9)Gd_(0.1)O_(2−δ)(GDC10)|SBSCCO+10wt%SZM15 anode-supported fuel cell at 850℃,highlighting the effectiveness of incorporating NTE materials as a promising strategy for regulating the thermomechanical properties and improving the long-term stability of intermediate temperature solid oxide fuel cells(IT-SOFCs).展开更多
For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial...For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function.展开更多
As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation ...As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.展开更多
The expansion of construction land on slopes in mountainous cities like Lanzhou has addressed the shortage of flat land but compromised slope stability,leading to uneven land subsidence and risks to infrastructure.Thi...The expansion of construction land on slopes in mountainous cities like Lanzhou has addressed the shortage of flat land but compromised slope stability,leading to uneven land subsidence and risks to infrastructure.This study assessed the land subsidence before and after urban expansion in five areas of Lanzhou by using slope spectrum construction method and gradient expansion intensity measurement that integrated with SBAS-InSAR technology.The results show that construction land on slopes over 20°increased significantly,accounting for 16%of new construction land.The average slope spectrum index was 4.02,with the upper slope limit rising by 8.2°.The land subsidence rate threshold increased by 10 mm/a,and the proportion of pixels experiencing subsidence greater than 5 mm/year rose from 3.63%to 5.24%.Increased construction intensity on slopes caused higher and faster subsidence,which diminished with greater distance from the expansion areas.Areas with slopes between 10°and 25°saw the greatest acceleration in subsidence.Geological composition,building density,groundwater exploitation,and cut-and-fill thickness collectively influence land subsidence rates.This study provides a scientific basis for mitigating geological disaster risks and promoting safe urban development in mountainous cities.展开更多
The ancient tacit knowledge behind the logic system permeated the culture and promoted numerous impactful inventions throughout the history. Traditional Chinese medicine with its effectiveness should also have stemmed...The ancient tacit knowledge behind the logic system permeated the culture and promoted numerous impactful inventions throughout the history. Traditional Chinese medicine with its effectiveness should also have stemmed out from such logic system. This article aims to rearticulate the underlying lucid multi-dimensional logic system, which faded in obscurity only because of time-out loss of the mid-right concept. Retracing this past tacit but important concept could uncover a multi-dimensional system over a point relating to all matters while capturing the central core of the matter. The seemingly unmanageable multidimensional logic was strengthened by verification processes which affirmed its further extensions, and made up the language of the people, the concepts of yin-yang(阴阳), and the development of extensions of Ba Gua(八卦) derivatives, which furthered the interpretation of the space-time properties and Chinese medicine.展开更多
Stress accumulation is a key factor leading to sodium storage performance deterioration for NiSe_(2)-based anodes.Therefore,inhibiting the concentrated local stress during the sodiataion/desodiation process is crucial...Stress accumulation is a key factor leading to sodium storage performance deterioration for NiSe_(2)-based anodes.Therefore,inhibiting the concentrated local stress during the sodiataion/desodiation process is crucial for acquiring stable NiSe2-based materials for sodium-ion batteries(SIBs),Herein,a stress dissipation strategy driven by architecture engineering is proposed,which can achieve ultrafast and ultralong sodium storage properties.Different from the conventional sphere-like or rod-like architecture,the three-dimensional(3D)flower-like NiSe_(2)@C composite is delicately designed and assembled with onedimensional nanorods and carbon framework.More importantly,the fundamental mechanism of improved structure stability is unveiled by simulations and experimental results simultaneously.It demonstrates that this designed multidimensional flower-like architecture with dispersed nanorods can balance the structural mismatch,avoid concentrated local strain,and relax the internal stress,mainly induced by the unavoidable volume variation during the repeated conversion processes.Moreover,it can provide more Na^(+)-storage sites and multi-directional migration pathways,leading to a fast Na^(+)-migration channel with boosted reaction kinetic.As expected,it delivers superior rate performance(441 mA h g^(-1)at 5.0 A g^(-1))and long cycling stability(563 mA h g^(-1)at 1.0 A g^(-1)over 1000 cycles)for SIBs.This work provides useful insights for designing high-performance conversion-based anode materials for SIBs.展开更多
This paper explores whole-process engineering consulting,including its application models in public buildings and elderly-friendly projects,such as service integration and whole lifecycle management.It also addresses ...This paper explores whole-process engineering consulting,including its application models in public buildings and elderly-friendly projects,such as service integration and whole lifecycle management.It also addresses the construction of multi-dimensional collaborative theoretical models,public space streamline organization,and other aspects,emphasizing the importance of multi-dimensional collaboration.Additionally,it highlights the role of talent cultivation and digital transformation in enhancing project efficiency.展开更多
The multi-dimensional interactive teaching model significantly enhances the effectiveness of college English instruction by emphasizing dynamic engagement between teachers and students,as well as among students themse...The multi-dimensional interactive teaching model significantly enhances the effectiveness of college English instruction by emphasizing dynamic engagement between teachers and students,as well as among students themselves.This paper explores practical strategies for implementing this model,focusing on four key aspects:deepening teachers’understanding of the model through continuous learning,innovating interactive methods such as questioning techniques and practical activities,leveraging modern technology to integrate resources and track learning progress,and establishing a communication platform that centers on student participation.By adopting these approaches,the model fosters a student-centered classroom environment,improves comprehensive English application skills,and optimizes overall teaching quality.展开更多
基金National Natural Science Foundation of China,No.41871178,No.41671385,No.41371172
文摘The study of multi-dimensional expansion of urban space(MEUS) addresses the laws of urban spatial expansion from all directions and angles. Using Nanjing as an example,this paper constructs multi-temporal, urban three-dimensional models based on RS and GIS technology and then conducts qualitative and quantitative analysis of MEUS using plot ratio change maps and MEUS quantitative index for built-up areas. Based especially on the concept of volume growth contribution rate, this paper analyzes the characteristics of MEUS in different stages. The results show that in 2000–2004, planar expansion played the main role,the internal potential development(IPD) intensity of the urban built-up areas was relatively large, and the volume growth contribution rate was low; in 2004–2008, planar expansion accelerated, and IPD slowed down; in 2008–2012, planar expansion slowed while IPD intensity increased; the contribution rates of volume growth of urban IPD for the three periods were 22.21%, 24.51% and 73.38%, respectively. This study expands the research perspective of urban spatial expansion, and the adopted methods are instructive and meaningful for MEUS research. In addition, the results of this study will deepen the understanding of MEUS laws and help improve scientific decision-making for urban planning and urban land use management.
基金supported by the National Natural Science Foundation of China(22072048)the Guangdong Provincial Department of Science and Technology(2021A1515010128 and 2022A0505050013).
文摘Succinonitrile(SN)-based polymer plastic crystal electrolytes(PPCEs)are regarded as promising candidates for lithium metal batteries but suffer from serious side reactions with Li metal.Herein,we propose a multi-dimensional optimization strategy to alleviate the side reactions between SN and Li metal,and develop a highly stable poly-vinylethylene carbonate-based PPCE(PPCE-VEC).Moreover,we identify the intrinsic factors of multi-dimensional polymer structures on the electrolyte stability by three typical classes of polyesters.The PPCE-VEC constructed by in situ polymerization exhibits much better stability than poly-vinylene carbonate-based PPCE(PPCE-VCA)and poly-trifluoroethyl acrylate-based PPCE(PPCE-TFA),which is verified by its fewer SN-decomposition species in X-ray photoelectron spectroscopy(XPS)and outstanding full cell performance.The PPCE-VEC-enabled LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)full cell achieve 73.7%capacity retention after 1400 cycles,which outperforms PPCE-VCA-and PPCE-TFA-enabled full cells(61.9%and 46.9%).Spectral analysis and theoretical calculation reveal that the high solvation ability of the carbonyl site,flexible polymer chain,and homogeneous electrolyte phase of PPCE-VEC are favorable to maximizing competition coordination with Li^(+)to weaken the Li^(+)–SN binding and shape an anion-rich solvation structure.This optimized polymer-involved Li^(+)solvation enhances SN stability and facilitates the formation of B/F enriched solid-electrolyte interphase(SEI),thus significantly improving PPCE stability.
基金financially supported by National Natural Science Foundation of China(No.52175321)the Fund of Key Laboratory of High Temperature Electromagnetic Materials and Structure of MOE(No.KB202505)。
文摘There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with high thermal conductivity.Furthermore,it explores the preparation of AlN_(P)/Mg-Zn-Cu composites featuring low coefficients of thermal expansion.The stir casting method was utilized to fabricate the composites and an investigation was conducted to examine their microstructure and thermal properties.Results indicate that the addition of AlN_(P)reduces the thermal expansion coefficient while maintaining relatively high thermal conductivity.Specifically,the AlN_(P)/Mg-0.5Zn-0.5Cu composite with 30wt.%AlN_(P)achieves a thermal conductivity of 132.7 W·m^(-1)·K^(-1)and a thermal expansion coefficient of 18.5×10^(-6)K^(-1),rendering it suitable for electronic packaging applications where thermal management is critical.
基金funded by the National Key R&D Program of China,China(No.2024YFF0507903)the National Key Research and Development Program of China(Grant No.2024YFF0507904)the National Natural Science Foundation of China,China(Grant No.52379114).These supports are gratefully acknowledged.
文摘In-situ enlargement of super-large-span tunnels can intensify excavation-induced unloading in the surrounding rock,increasing deformation demand and failure risk during construction.This study combines laboratory model tests with FLAC3D simulations to evaluate the stabilizing role of prestressed anchor cables and to establish an energy-balance framework for support optimization.Comparative model tests of existing and enlarged tunnel sections,with and without anchors,show that reinforcement increases load-carrying capacity,reduces displacement,and confines damage to more localized zones.The numerical simulations reproduce displacement fields,shear-strain localization,and plastic-zone evolution with good agreement against the experimental observations.The energy framework is implemented in the in-situ simulations by quantifying unloading-related energy release in the rock mass and reinforcement work contributed by the anchors,and by introducing an energy release–reinforcement ratio as a stability indicator.Parametric analyses indicate that anchor length,spacing,and prestress influence stability in a nonlinear manner,with diminishing returns once reinforcement extends beyond the mechanically dominant deformation zone.An efficient parameter window is identified that improves deformation and yielding control while avoiding unnecessary reinforcement.The results provide an energy-consistent and design-oriented basis for prestressed anchorage selection in large-span tunnel expansion.
基金financial support from the National Natural Science Foundation of China(No.22478278,22308246)the Central Government Guides the Local Science and Technology Development Special Fund(No.YDZJSX20231A015)the Fundamental Research Program of Shanxi Province(No.202203021212266).
文摘The metallic Ni catalyst suffers from strong binding with the*CO intermediate,resulting in poisoning of the catalyst surface.It is feasible to facilitate the generation of CO by alleviating the binding strength of the*CO intermediate on the Ni metal surface through a lattice expansion strategy.Here,Ni_(3)ZnC_(0.7)@C with lattice expansion was synthesized by co-doping with Zn and interstitial C through high-temperature pyrolysis.Structural characterization confirms that the lattice of Ni_(3)ZnC_(0.7)expands by 5.47%compared to Ni due to the co-doping of Zn and interstitial C.The Ni_(3)ZnC_(0.7)@C possesses excellent catalytic performance with Faradaic efficiency(FE)of CO exceeding 90%over a wide potential range from−0.8 to−1.4 V versus reversible hydrogen electrode(vs.RHE)with a peak FECO of 96.6%at−1.0 V vs.RHE.In membrane electrode assembly(MEA)testing,Ni_(3)ZnC_(0.7)@C achieves a FECO of 81.4%at the industrial-level current density of 400 mA cm^(−2).In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)and density functional theory(DFT)calculations reveal that the co-introduction of Zn and interstitial C in the Ni crystal can significantly promote the desorption of*CO intermediate,which facilitates the generation of CO.This study demonstrates a viable way for designing efficient transition metal catalysts for CO_(2)electroreduction through lattice strain engineering.
基金National Key R&D Program of China(2022YFB2602900)R&D Fund Project of China Academy of Railway Sciences Corporation Limited(2021YJ084)+2 种基金Project of Science and Technology R&D Program of China Railway(2016G002-K)R&D Fund Project of China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.(2021)R&D Fund Project of China Railway Shanghai Group(2021141).
文摘Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.
基金co-supported by the National Key R&D Program of China(No.2023YFB4704400)the Zhejiang Provincial Natural Science Foundation of China(No.LQ24F030012)the National Natural Science Foundation of China General Project(No.62373033)。
文摘A composite anti-disturbance predictive control strategy employing a Multi-dimensional Taylor Network(MTN)is presented for unmanned systems subject to time-delay and multi-source disturbances.First,the multi-source disturbances are addressed according to their specific characteristics as follows:(A)an MTN data-driven model,which is used for uncertainty description,is designed accompanied with the mechanism model to represent the unmanned systems;(B)an adaptive MTN filter is used to remove the influence of the internal disturbance;(C)an MTN disturbance observer is constructed to estimate and compensate for the influence of the external disturbance;(D)the Extended Kalman Filter(EKF)algorithm is utilized as the learning mechanism for MTNs.Second,to address the time-delay effect,a recursiveτstep-ahead MTN predictive model is designed utilizing recursive technology,aiming to mitigate the impact of time-delay,and the EKF algorithm is employed as its learning mechanism.Then,the MTN predictive control law is designed based on the quadratic performance index.By implementing the proposed composite controller to unmanned systems,simultaneous feedforward compensation and feedback suppression to the multi-source disturbances are conducted.Finally,the convergence of the MTN and the stability of the closed-loop system are established utilizing the Lyapunov theorem.Two exemplary applications of unmanned systems involving unmanned vehicle and rigid spacecraft are presented to validate the effectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(Grant No.52374170)the Major Special Projects of the Third Comprehensive Scientific Exploration in Xinjiang(Grant No.2022xjkk1005)the Fundamental Research Funds for the Central Universities(Grant No.B230207001)。
文摘Global population growth and rising standards of living are the driving factors for the cropland expansion to meet increasing demands.However,there is no clear assessment of the specific losses on ecosystem services caused by China's expansion of cropland to ensure food security at the cost of losing ecological land such as forests and grasslands.This study employed the ArcGIS platform and integrated valuation of ecosystem services and tradeoffs(InVEST)model to explore the cropland expansion in China from 2000 to 2020 and its impact on ecosystem services,so as to predict the priority areas of future cropland expansion in different scenarios.The results indicated that in the past 20 years,the total area of cropland expansion in China was 17.04 million hm^(2)with 70.79% conversion from forests and grasslands.Cropland expansion has contributed to an overall improvement in the food supply services with the Northern Arid and Semi-Arid Region exhibiting an increase of 18.76×10^(6) tons,while concurrently leading to a decline in habitat quality services.The priority areas for future cropland expansion without ecological loss were found to be 1.42 million hm^(2),which only account for 9.44% of the total reclaimable land.To minimize the loss of ecosystem services,there is a need to adjust the cropland replenishment policies and provide an operational solution for global food security and ecological protection.
基金financially supported by the CITIC niobium steel development award Fund(M1656-2021)Central Iron and Steel Research Institute for its independent research and development fund(No.21G62460ZD).
文摘Increasing the hole expansion ratio is significant for developing high formability parts.Hole expansion tests were carried out on low carbon hot-rolled steel containing 0.11%Ti,0.072%Ti–0.03%Nb and 0.097%Ti–0.059%Nb,respectively.The effects of microstructure,texture,crack propagation behavior and second phase precipitation behavior on hole expansion ratio were investigated.The precipitation behavior of TiC and(Ti,Nb)C in austenite and ferrite in three groups of steel samples was calculated theoretically.The results showed that the hole expansion ratios of 0.11Ti,0.072Ti–0.03Nb and 0.097Ti–0.059Nb test steels were 51.73%,51.17%and 66.24%following simulated coiling at 600℃,respectively.The microstructure was mainly polygonal ferrite with a small amount of pearlite.The grain refinement of 0.097Ti–0.059Nb test steel and the low texture ratio of{110}//ND improved the hole expansion ratio.The low overall hole expansion ratio was due to the microstructure inhomogeneity.The microstructure uniformity was improved by the quenching and tempering treatment,and the hole expansion ratio of the three test steels was greatly increased.The fastest precipitation temperatures in the austenitic region of 0.11Ti,0.072Ti–0.03Nb and 0.097Ti–0.059Nb test steels were 880,860 and 830℃,while those in the ferrite region were 680,675 and 675℃,respectively.The addition of Nb element increased the volume free energy,so that the critical core size of the nucleation on the dislocation line increased,resulting in the decrease in the fastest precipitation temperature.
基金financially supported by the National Natural Science Foundation of China(Nos.22271309,12425403 and 12261131499)the National Key R&D Program of China(No.2021YFA1400300)+2 种基金financial support from the Science and Technology Development Fund from Macao SAR(No.0062/2023/ITP2)Macao Polytechnic University(No.RP/FCA-03/2023)Synchrotron X-ray powder diffraction experiments were conducted at SPring-8,approved by the Japan Synchrotron Radiation Research Institute(Nos.2024A1506,2024A1695 and 2024B1807)
文摘Negative thermal expansion(NTE)is a notable physical property where a material’s volume decreases instead of increasing when heated.The identification of NTE materials is crucial for thermal expansion control engineering.Most NTE materials exhibit NTE only within a narrow temperature range,restricting their applications.Achieving NTE across a broad temperature range remains a significant challenge.This study developed a novel PbTiO_(3)-based system,(1-x)PbTiO_(3–x)BiLuO_(3),incorporating rare-earth elements,using a distinctive high-pressure and high-temperature synthesis technique.We achieved NTE across a broad temperature range by coupling lattice(c/a)with ferroelectric order parameters.The incorporation of BiLuO_(3)resulted in distinctive ferroelectric characteristics,including increased tetragonality,spontaneous polarization,and NTE over a broad temperature range.NTE over an extended temperature range has been achieved in 0.95PbTiO_(3)–0.05BiLuO_(3)(■=−1.7×10^(–5)K^(−1),300–840 K)and 0.90PbTiO_(3)–0.10BiLuO_(3)(■=−1.4×10^(–5)K^(−1),300–860 K),compared to pristine PbTiO_(3)(■=−1.99×10^(–5)K^(−1),300–763 K).The improved tetragonalities and broader NTE temperature range result from the strong hybridization of Pb/Bi–O and Ti/Lu–O atoms,as demonstrated by combined experimental and theoretical analyses,including high-energy synchrotron X-ray diffraction,Raman spectroscopy,and density functional theory calculations.This study introduces a novel example of NTE over a broad temperature range,highlighting its potential as a high-performance thermal expansion compensator.Additionally,it presents an effective method for incorporating rare-earth elements to achieve NTE in PbTiO_(3)-based perovskites across a wide temperature range.
基金supported by the National Natural Science Foundation of China(52476200,52106244)the Guangdong Basic and Applied Basic Research Foundation(2024A1515030124)+1 种基金the Science and Technology Project of China Southern Power Grid under Grant GDKJXM20230246(030100KC23020017)the Fundamental Research Funds for the Central Universities。
文摘Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the degradation behavior and failure mechanism of various overcharged states(100%SOC,105%SOC,110%SOC,and 115%SOC),multiple advanced in-situ characterization techniques(accelerating rate calorimeter,electrochemical impedance spectroscopy,ultrasonic scanning,and expansion instrument)were utilized.Additionally,re-overcharge-induced thermal runaway(TR)tests were conducted,with a specific emphasis on the evolution of the expansion force signal.Results indicated significant degradation at 110%SOC including conductivity loss,loss of lithium inventory,and loss of active material accompanied by internal gas generation.These failure behaviors slow down the expansion force rate during reovercharging,reducing the efficacy of active warnings that depend on rate thresholds of expansion force.Specifically,the warning time for 115%SOC battery is only 144 s,which is 740 s shorter than that for fresh battery,and the time to TR is advanced by 9 min.Moreover,the initial self-heating temperature(T1)is reduced by 62.4℃compared to that of fresh battery,reaching only 70.8℃.To address the low safety of overcharged batteries,a passive overcharge warning method utilizing relaxation expansion force was proposed,based on the continued gas generation after stopping charging,leading to a sustained increase in force.Compared to active methods that rely on thresholds of expansion force rate,the passive method can issue warnings 115 s earlier.By combining the passive and active warning methods,guaranteed effective overcharge warning can be issued 863-884 s before TR.This study introduces a novel perspective for enhancing the safety of batteries.
基金National Natural Science Foundation of China(Nos.42171130 and 42301158)Pilot Project of China’s Strength in Transportation for the Central Research Institute(No.QG2021-1-4-7)National Key Technology Research and Development Program of the Ministry of Science and Technology of China(No.2021YFB2601200).
文摘Sulfate attack-induced expansion of cement-treated aggregates in seasonally frozen regions is a well-known issue which causes continuous expansion in railway subgrades,and particularly in high-speed railways.Accordingly,we investigated the influence of material proportions,the number of freeze-thaw(FT)cycles,and temperature gradients on the expansion mechanism of sulfate attack on cement-treated aggregates subjected to FT cycles.The conditions,laws,and dominant factors causing the expansion of aggregates were analyzed through swelling tests.The results indicate that under FT cycles,3%content cement-treated graded macadam only experiences slight deformation.The maximum strain of graded macadam attacked by 1%sodium sulfate content in each FT cycle is significantly larger than that of 3%content cement-treated graded macadam attacked by 1%sodium sulfate content.Using scanning electron microscopy,needle-like crystals were observed during sulfate attack of cement-treated graded macadam.Through quantitative analysis,we determined the recoverable and unrecoverable deformations of graded macadam under FT cycles.For graded macadam under sulfate attack,the expansion is mainly induced by periodic frost heave and salt expansion,as well as salt migration.For cement-treated graded macadam under sulfate attack,the expansion is mainly induced by chemical attack and salt migration.This study can serve as a reference for future research on the mechanics of sulfate attack on cement-treated aggregates that experience FT cycles,and provide theoretical support for methods that remediate the expansion induced by sulfate attack.
基金supported by the research project within the program“Excellence Initiative-Research University”for the AGH University of Krakow(IDUB AGH,Action 21)Kun Zheng acknowledges financial support from AGH University of Krakow(No.16.16.210.476).
文摘Minimizing the thermal expansion coefficient(TEC)mismatch between the cathode and electrolyte in solid oxide fuel cells is crucial for achieving stable,durable operation and high performance.Recently,materials with negative thermal expansion(NTE)have at-tracted significant attention as effective additives for tailoring the thermomechanical properties of electrodes and enhancing cell durability.In this work,for the first time,single-phase NTE perovskite Sm_(0.85)Zn_(0.15)MnO_(3−δ)(SZM15)was successfully synthesized via the sol-gel method,eliminating the unwanted ZnO phase typically observed in materials obtained through the conventional solid-state reaction route.The sol-gel approach proved highly advantageous,offering low cost,robustness,excellent chemical homogeneity,precise compositional control,and high phase purity.After optimization of synthesis parameters,a negative TEC of approximately−6.5×10^(−6)K^(−1)was achieved in the 400-850℃range.SZM15 was then incorporated as an additive(10wt%-50wt%)into a SmBa0.5Sr0.5CoCuO_(5+δ)(SBSCCO)cathode to tune the thermomechanical properties with a La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.2)O_(3−δ)(LSGM)electrolyte,achieving a minimal TEC mismatch of only 1%.Notably,the SBSCCO+10wt%SZM15 composite cathode exhibited the lowest polarization resistance of 0.019Ω·cm^(2)at 900℃,showing approximately 70%lower than that of the pristine cathode.Excellent long-term stability after 100 h of operation was achieved.In addition,a high peak power density of 680 mW·cm^(−2)was achieved in a Ni-YSZ(yttria-stabilized zirconia)|YSZ|Ce_(0.9)Gd_(0.1)O_(2−δ)(GDC10)|SBSCCO+10wt%SZM15 anode-supported fuel cell at 850℃,highlighting the effectiveness of incorporating NTE materials as a promising strategy for regulating the thermomechanical properties and improving the long-term stability of intermediate temperature solid oxide fuel cells(IT-SOFCs).
基金Supported by Projects from Chongqing Municipal Science and Technology Commission(CSTB2022NSCQ-MSX0445)。
文摘For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function.
基金supported by the Fundamental Research Funds for the Central Universities(WK2090000055)Anhui Provincial Natural Science Foundation of China(2308085QG231).
文摘As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.
基金National Natural Science Foundation of China(Grant No.42271214)National Key R&D Program of China(Grant No.2022YFC3800700)+1 种基金Key Research Program of Gansu Province(Grant No.23ZDKA0004)Natural Science Foundation of Gansu Province(Grant No.21JR7RA281).
文摘The expansion of construction land on slopes in mountainous cities like Lanzhou has addressed the shortage of flat land but compromised slope stability,leading to uneven land subsidence and risks to infrastructure.This study assessed the land subsidence before and after urban expansion in five areas of Lanzhou by using slope spectrum construction method and gradient expansion intensity measurement that integrated with SBAS-InSAR technology.The results show that construction land on slopes over 20°increased significantly,accounting for 16%of new construction land.The average slope spectrum index was 4.02,with the upper slope limit rising by 8.2°.The land subsidence rate threshold increased by 10 mm/a,and the proportion of pixels experiencing subsidence greater than 5 mm/year rose from 3.63%to 5.24%.Increased construction intensity on slopes caused higher and faster subsidence,which diminished with greater distance from the expansion areas.Areas with slopes between 10°and 25°saw the greatest acceleration in subsidence.Geological composition,building density,groundwater exploitation,and cut-and-fill thickness collectively influence land subsidence rates.This study provides a scientific basis for mitigating geological disaster risks and promoting safe urban development in mountainous cities.
文摘The ancient tacit knowledge behind the logic system permeated the culture and promoted numerous impactful inventions throughout the history. Traditional Chinese medicine with its effectiveness should also have stemmed out from such logic system. This article aims to rearticulate the underlying lucid multi-dimensional logic system, which faded in obscurity only because of time-out loss of the mid-right concept. Retracing this past tacit but important concept could uncover a multi-dimensional system over a point relating to all matters while capturing the central core of the matter. The seemingly unmanageable multidimensional logic was strengthened by verification processes which affirmed its further extensions, and made up the language of the people, the concepts of yin-yang(阴阳), and the development of extensions of Ba Gua(八卦) derivatives, which furthered the interpretation of the space-time properties and Chinese medicine.
基金the financial support from the Guangxi Natural Science Foundation(grant no.2021GXNSFDA075012,2023GXNSFGA026002)National Natural Science Foundation of China(52104298,22075073,52362027,52462029)Fundamental Research Funds for the Central Universities(531107051077).
文摘Stress accumulation is a key factor leading to sodium storage performance deterioration for NiSe_(2)-based anodes.Therefore,inhibiting the concentrated local stress during the sodiataion/desodiation process is crucial for acquiring stable NiSe2-based materials for sodium-ion batteries(SIBs),Herein,a stress dissipation strategy driven by architecture engineering is proposed,which can achieve ultrafast and ultralong sodium storage properties.Different from the conventional sphere-like or rod-like architecture,the three-dimensional(3D)flower-like NiSe_(2)@C composite is delicately designed and assembled with onedimensional nanorods and carbon framework.More importantly,the fundamental mechanism of improved structure stability is unveiled by simulations and experimental results simultaneously.It demonstrates that this designed multidimensional flower-like architecture with dispersed nanorods can balance the structural mismatch,avoid concentrated local strain,and relax the internal stress,mainly induced by the unavoidable volume variation during the repeated conversion processes.Moreover,it can provide more Na^(+)-storage sites and multi-directional migration pathways,leading to a fast Na^(+)-migration channel with boosted reaction kinetic.As expected,it delivers superior rate performance(441 mA h g^(-1)at 5.0 A g^(-1))and long cycling stability(563 mA h g^(-1)at 1.0 A g^(-1)over 1000 cycles)for SIBs.This work provides useful insights for designing high-performance conversion-based anode materials for SIBs.
文摘This paper explores whole-process engineering consulting,including its application models in public buildings and elderly-friendly projects,such as service integration and whole lifecycle management.It also addresses the construction of multi-dimensional collaborative theoretical models,public space streamline organization,and other aspects,emphasizing the importance of multi-dimensional collaboration.Additionally,it highlights the role of talent cultivation and digital transformation in enhancing project efficiency.
文摘The multi-dimensional interactive teaching model significantly enhances the effectiveness of college English instruction by emphasizing dynamic engagement between teachers and students,as well as among students themselves.This paper explores practical strategies for implementing this model,focusing on four key aspects:deepening teachers’understanding of the model through continuous learning,innovating interactive methods such as questioning techniques and practical activities,leveraging modern technology to integrate resources and track learning progress,and establishing a communication platform that centers on student participation.By adopting these approaches,the model fosters a student-centered classroom environment,improves comprehensive English application skills,and optimizes overall teaching quality.
