The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and...The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and X-ray diffractometer,combined with software tools like Matlab,Image-Pro Plus,and CHANNEL5,the influence mechanism of rare earth element addition on the strength,toughness,and inclusions of deposited metal in 1000 MPa grade high-strength steel was investigated.The results indicate that the incorporation of rare earth elements enhances the weldability of the welding materials.With the addition of rare earth elements,the tensile strength of the deposited metal increases from 935 MPa to 960 MPa.However,further addition leads to a decrease in tensile strength,while the yield strength continuously increases by 8.5%-17.2%.The addition of appropriate amounts of rare earth elements results in an increase in acicular ferrite and retained austenite content,as well as grain refinement in the deposited metal,leading to 8.5%-24.3% and 15.6%-42.2% enhancement in impact energy at−40℃ and−60℃,respectively.Additionally,the proper addition of rare earth elements modifies the inclusions and generates fine and dispersed composite inclusions that bond better with the matrix,thereby optimizing the properties of the deposited metal through various mechanisms.Adding an appropriate amount of rare earth elements can significantly enhance the properties of the deposited metal in 1000 MPa grade high-strength steel,and improve the match between high strength and toughness,meeting the demands for high-strength steel used in hydropower applications.展开更多
Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,a...Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.展开更多
Ultra-high performance fiber-reinforced concrete (UHPFRC) has received extensive attention from scholars and engineers due to its excellent mechanical properties and durability. However, there is a mutually restrictiv...Ultra-high performance fiber-reinforced concrete (UHPFRC) has received extensive attention from scholars and engineers due to its excellent mechanical properties and durability. However, there is a mutually restrictive relationship between the workability and mechanical properties of UHPFRC. Specifically, the addition of fibers will affect the workability of fresh UHPFRC, and the workability of fresh UHPFRC will also affect the dispersion and arrangement of fibers, thus significantly influencing the mechanical properties of hardened UHPFRC. This paper first analyzes the research status of UHPFRC and the relationship between its workability and mechanical properties. Subsequently, it outlines the test methods and indicators of UHPFRC workability, including fluidity, slump, V-funnel passing time, and rheology. Then, it reviews the impacts of metal fibers, synthetic fibers, hybrid fibers, and other fibers on the workability and mechanical properties of UHPFRC, and presents a reasonable range of fiber dosage for workability and mechanical properties. Key findings include: (1) Steel fibers within 1%–2% volume optimize workability-mechanical balance, while exceeding 2.5% reduces compressive strength by 7%–30%;(2) Hybrid steel-polypropylene fibers enhance toughness by 65%;(3) Fiber orientation control via rheology-modifying admixtures improves flexural strength by up to 64%. This review establishes a fiber factor (V·L/D) for predictive mix design, advancing beyond empirical approaches in prior studies.展开更多
To guarantee secure communication against eavesdropping and malicious attack,an artificial noise(AN)-aided frequency-hopping(FH)architecture is adopted in this article.But the inevitable time misalignment between the ...To guarantee secure communication against eavesdropping and malicious attack,an artificial noise(AN)-aided frequency-hopping(FH)architecture is adopted in this article.But the inevitable time misalignment between the received signal and locally reconstructed AN will deteriorate the AN cancellation performance,yielding significant secrecy degradation at the FH receiver.In view of this,first,the AN cancellation performance under time misalignment is evaluated via signal to AN-plus-noise ratio,and the system secrecy is analyzed via secrecy rate.Then,to mitigate the performance degradation raised by time misalignment,the transmitting power allocation scheme for AN and confidential signal(CS)is optimized,and the optimal hopping period is designed.Notably,the obtained conclusions in both the performance evaluation and transmitter optimization sections hold no matter whether the eavesdropper can realize FH synchronization or not.Simulations verify that time misalignment will raise non-negligible performance degradation.Besides,the power ratio of AN to CS should decrease as time misalignment increases,and for perfect time synchronization,the transmitting power of AN and CS should be equivalent.In addition,a longer hopping period is preferred for secrecy enhancement when time misalignment gets exacerbated.展开更多
Carbonaceous mudstone is a potential embankment filler in mountainous regions with limited high-quality materials;however,its engineering performance in highway embankments under complex environmental conditions remai...Carbonaceous mudstone is a potential embankment filler in mountainous regions with limited high-quality materials;however,its engineering performance in highway embankments under complex environmental conditions remains poorly understood.This study aimed to investigate the mechanical properties and failure mechanisms of carbonaceous mudstone filler under different temperature-moisture coupled conditions.Triaxial shear tests were conducted under four temperaturemoisture coupled conditions:dry-heat to dry-cold(DHDC),wet-cold to wet-heat(WCWH),dry-cold to wet-heat(DCWH),and dry-heat to wet-cold(DHWC).The effects of these conditions on the strength characteristics,relative breakage ratio,failure mode,and microscopic morphology were examined.A segmented prediction model based on the DuncanChang model was applied to validate the experimental results under the DHWC condition.The failure mechanisms under different conditions were also analyzed.The results indicate that the degradation of carbonaceous mudstone increases in the following order:DHDC,WCWH,DCWH,and DHWC.Under the DHDC condition,the stress-strain curves exhibit strain-softening behavior,while other conditions show strain-hardening behavior,with peak deviatoric stress occurring at 2%and 4%axial strains,respectively.The shear strength decreases by up to 40%under the DHWC condition but remains nearly unchanged under the DHDC condition,showing a positive correlation with particle breakage.As the number of cycles increases,the failure surfaces gradually move downward.Higher confining pressure shifts failure mode from shear failure to shear slip or localized compression,and eventually to overall compression or expansion failure.The modified Duncan-Chang model accurately predicts the experimental results.These findings provide important guidance for the application of carbonaceous mudstone filler in highway embankment construction in humid mountainous regions.展开更多
Anaerobic digestion (AD) with thermal hydrolysis (TH) pretreatment is a promising process for excess sludge treatment,while there lacks of the knowledge from full-scale process about the impact of sludge composition a...Anaerobic digestion (AD) with thermal hydrolysis (TH) pretreatment is a promising process for excess sludge treatment,while there lacks of the knowledge from full-scale process about the impact of sludge composition and characteristics on microbial community and performance.The sludge physiochemical indices,microbial community and performance data of four full-scale TH-AD plants were characterized,and their relationships was elucidated.The four plants were operated under almost similar total organic loading rate (OLR)but their methanogenesis performance differentiate into two groups,namely superior group(SupG) and the inferior group (Inf G).In both groups,TH effectively solubilized particulate organic compounds,meanwhile raised the ammonia nitrogen (NH_(4)^(+)-N) and volatile fatty acid (VFA) concentration.Compared with the Sup G,thermal hydrolyzed sludge of Inf G had higher level of VFAs,NH_(4)^(+)-N and total chemical oxygen demand (t COD),which showed higher inhibition effect on microbes,leading to a community with lower diversity,lower abundance of carbohydrate degrading functional guild,higher protein degrading one,and methanogens that adapted to limited substrates,and further declined the methane production rate.Thus,it was recommended that OLR alone was not sufficient for controlling the system in design and operation,the concentration of VFAs,NH_(4)^(+)-N and t COD should be equally considered.Their higher concentration,together with the higher abundance of Defluviitoga and Proteiniphilum were recommended as indicators for inferior running condition.Our results proposed that microbial communities played a role of bridge between environmental factors and performance,provided implications for engineering ecology and operational regulation for full-scale sludge TH-AD process.展开更多
Static recrystallization(SRX)characteristics of a powder metallurgy superalloy were investigated by isothermal compression at 1080–1170℃ under strain rates of 0.01–0.1 s^(−1),strains of 0.1,0.22,or 0.5,and holding ...Static recrystallization(SRX)characteristics of a powder metallurgy superalloy were investigated by isothermal compression at 1080–1170℃ under strain rates of 0.01–0.1 s^(−1),strains of 0.1,0.22,or 0.5,and holding time of 0–300 s.The impacts of temperature,strain rate,holding time,and strain on the SRXed grain size,volume fraction,and microtexture were explored by electron backscatter diffraction technique.It was found that temperature played a key role in these processes.As SRX progressed,the<110>fiber parallel to the axis compression direction gradually weakened and was replaced by the<001>fiber because<001>was the preferred recrystallization orientation and grain growth direction for the Ni-based superalloy.Moreover,high temperatures and low strain rates promoted the formation of the<001>fiber.Three nucleation mechanisms during SRX process were found:grain boundary bulging,primary twin assistance,and subgrain coalescence.Grain boundary bulging occurred under all process conditions;however,at low temperatures and high strain rates,the latter two mechanisms could provide additional nucleation modes.In addition,SRX size and volume fraction models were established.展开更多
The dual-rotor structure serves as the primary source of vibration in aero-engines. Understanding itsdynamical model and analyzing dynamic characteristics, such as critical speed and unbalanced response, arecrucial fo...The dual-rotor structure serves as the primary source of vibration in aero-engines. Understanding itsdynamical model and analyzing dynamic characteristics, such as critical speed and unbalanced response, arecrucial for rotor system dynamics. Previous work introduced a coaxial dual-rotor-support scheme for aeroengines,and a physical model featuring a high-speed flexible inner rotor with a substantial length-to-diameter ratiowas designed. Then a finite element (FE) dynamic model based on the Timoshenko beam elements and rigid bodykinematics of the dual-rotor system is modeled, with the Newmark method and Newton–Raphson method used forthe numerical calculation to study the dynamic characteristics of the system. Three different simulation models,including beam-based FE (1D) model, solid-based FE (3D) model, and transfer matrix model, were designed tostudy the characteristics of mode and the critical speed characteristic of the dual-rotor system. The unbalancedresponse of the dual-rotor system was analyzed to study the influence of mass unbalance on the rotor system. Theeffect of different disk unbalance phases and different speed ratios on the dynamic characteristics of the dual-rotorsystem was investigated in detail. The experimental result shows that the beam-based FE model is effective andsuitable for studying the dual-rotor system.展开更多
The new energy vehicle body composed of multi-metals requires a synchronous chemical conversion coating to exhibit excellent corrosion resistance.Herein,we prepared a titanium/zirconium/water-based oligomeric epoxy si...The new energy vehicle body composed of multi-metals requires a synchronous chemical conversion coating to exhibit excellent corrosion resistance.Herein,we prepared a titanium/zirconium/water-based oligomeric epoxy silane composite chemical conversion coating on multi-metals,and conducted an investigation into its electrochemical behavior and micro-zone structural characteristics upon immersion in a 3.5%NaCl solution.The electrochemical results combined with characterization results revealed that the corrosion evolution characteristics of the composite coatings could be categorized into three stages of mild corrosion,synergistic protection,and substrate damage.Besides,Si-OH groups interact with Me-OH at the defect on the multi-metal surface to form an organic monolayer coating.This organic monolayer coating,in conjunction with the synergistic inorganic conversion layer comprising Al_(2)O_(3),TiO_(2),2H_(2)O,ZrO_(2),2H_(2)O,effectively cooperates with the corrosion products to hinder the erosion by the corrosive medium and suppresses the progression of the anodic reaction.展开更多
Lithium-ion batteries are used extensively in civil,military,and aerospace applications because of their high energy and power density.However,in practical applications,these batteries may encounter extreme cases char...Lithium-ion batteries are used extensively in civil,military,and aerospace applications because of their high energy and power density.However,in practical applications,these batteries may encounter extreme cases characterized by transient high impacts,which impose stringent requirements on their safety and reliability.In recent years,the failure mechanism associated with the short-circuiting of lithium-ion-battery separators under high dynamic impacts has been investigated thoroughly.Based on the separator impact failure mechanism,we prepared a porous polymer polyvinylidene fluoride(PVDF)separator by doping gas-phase SiO_(2)(fumed silica)additive.The gas-phase SiO_(2)has a unique three-dimensional cluster structure,which is impact resistant.The impact resistance of the battery separator was tested using a highdynamic-impact system.The voltage drop of the battery with 3%SiO_(2)content was 33.04%of that of the original PVDF battery.Material characterization of the separator was further explored by scanning electron microscope,static compression,and pore-size adsorption tests.The SiO_(2)with a special cluster structure was distributed uniformly on the surface of the separator and embedded in the inner walls of the pores.Under static compression,the current of the SiO_(2)-PVDF separator with 3%content rose at a lower rate than that of the PVDF separator,with a minimum current of 1.04 mA.After adding SiO_(2),the separator pore size increased from 5 to 20 nm.Also,we used COMSOL to conduct impact simulations of different separators.The calculation results showed that the deformation(9.98%)and internal electrode current(0.018 A)of the SiO_(2)-PVDF lithium-ion battery were lower than the deformation(23.09%)and internal electrode current(0.049 A)of the PVDF lithium-ion battery.The SiO_(2)-doped composite polymer separator with a special cluster structure plays a crucial role in enhancing the impact resistance of lithium-ion batteries.展开更多
Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This...Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.展开更多
The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deci...The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deciphering their adhesion mechanism.This study developed a contact mechanics model based on van der Waals forces and frictional self-locking effects,incorporating both the spatular pad and spatular shaft of the gecko’s foot microstructures.Building on this foundation,a discrete element simulation model was established using the bonding method to replicate the contact between the gecko's spatula and different surfaces.The dynamic adhesion and detaching processes under normal and tangential external forces were simulated,allowing for the analysis of variation curves of normal and tangential adhesion forces at different detaching angles.This provided insights into the directional adhesion mechanics of the gecko's spatula.Furthermore,a force measurement system was constructed using a multi-degree-of-freedom nano-manipulator and an atomic force microscope within a scanning electron microscope.This system was used to experimentally test the adhesion characteristics of the gecko’s foot microstructures,validating the accuracy of the proposed adhesion mechanics model.展开更多
The current research of titanium alloy on friction welding process in the field of aero-engines mainly focuses on the linear friction welding.Compared to the linear friction welding,inertial friction welding of titani...The current research of titanium alloy on friction welding process in the field of aero-engines mainly focuses on the linear friction welding.Compared to the linear friction welding,inertial friction welding of titanium alloy still has important application position in the welding of aero-engine rotating assembly.However,up to now,few reports on inertial friction welding of titanium alloy are found.In this paper,the near-alpha TA19 titanium alloy welded joint was successfully obtained by inertial friction welding(IFW)process.The microstructures and mechanical properties were investigated systematically.Results showed that the refined grains within 15‒20μm and weak texture were found in the weld zone due to dynamic recrystallization caused by high temperature and plastic deformation.The weld zone consisted of acicularα′martensite phase,αp phase and metastableβphase.Most lath-shapedαs andβphase in base metal were transformed into acicular martensiteα′phase and metastableβphase in thermo-mechanically affected zone and heat affected zone.As a result,the microhardness of welded joint gradually decreased from the weld zone to the base metal.Tensile specimens in room temperature and high temperature of 480℃ were all fractured in base metal illustrating that the inertia friction welded TA19 titanium alloy joint owned higher tensile strength compared to the base metal.展开更多
Digital patternless freeze-casting technology is a new approach for obtaining frozen sand moulds using digital milling technology. The change law of tensile strength and air permeability of frozen sand moulds (100-mes...Digital patternless freeze-casting technology is a new approach for obtaining frozen sand moulds using digital milling technology. The change law of tensile strength and air permeability of frozen sand moulds (100-mesh and 200-mesh silica sand, and zircon sand moulds) under different freezing temperatures and water contents was studied. Results show that with the decrease of freezing temperature and the increase of water contents, the tensile strength and air permeability of the sand moulds are gradually improved. Meanwhile, computed tomography technology was used to characterize the shape and size of the water film between the sand particles mixed with 4wt.% water. The results show that in silica sand moulds, the form of water film is lumpy, and 200-mesh silica sand moulds have more water films and higher proportion of small-sized water films than 100-mesh silica sand moulds, while in zircon sand moulds, the form of water film is membranous. At the same freezing temperature and water content, the tensile strength of zircon sand mould is the highest, and 100-mesh silica sand mould is the lowest. A comparative solidification experiment of A356 aluminum alloy was carried out in frozen sand mould and resin sand mould. The results show that the primary α-Al phase appears in the form of equiaxed and eutectic silicon phase is needle-like in freezing sand mould casting, but the primary α-Al phase grows in the form of dendrites, and the eutectic silicon phase is coarse needle-like in the resin sand mould casting. The difference of microstructure is caused by the different cooling rate. The cooling rate of A356 aluminum alloy in frozen sand mould is higher than that in resin sand mould.展开更多
Background:Attrition rate in new army recruits is higher than in incumbent troops.In the current study,we identified the risk factors for attrition due to injuries and physical fitness failure in recruit training.A va...Background:Attrition rate in new army recruits is higher than in incumbent troops.In the current study,we identified the risk factors for attrition due to injuries and physical fitness failure in recruit training.A variety of predictive models were attempted.Methods:This retrospective cohort included 19,769 Army soldiers of the Australian Defence Force receiving recruit training during a period from 2006 to 2011.Among them,7692 reserve soldiers received a 28-day training course,and the remaining 12,077 full-time soldiers received an 80-day training course.Retrieved data included anthropometric measures,course-specific variables,injury,and physical fitness failure.Multivariate regression was used to develop a variety of models to predict the rate of attrition due to injuries and physical fitness failure.The area under the receiver operating characteristic curve was used to compare the performance of the models.Results:In the overall analysis that included both the 28-day and 80-day courses,the incidence of injury of any type was 27.8%.The 80-day course had a higher rate of injury if calculated per course(34.3%vs.17.6%in the 28-day course),but lower number of injuries per person-year(1.56 vs.2.29).Fitness test failure rate was significantly higher in the 28-day course(30.0%vs.12.1%).The overall attrition rate was 5.2%and 5.0%in the 28-day and 80-day courses,respectively.Stress fracture was common in the 80-day course(n=44)and rare in the 28-day course(n=1).The areas under the receiver operating characteristic curves for the course-specific predictive models were relatively low(ranging from 0.51 to 0.69),consistent with"failed"to"poor"predictive accuracy.The course-combined models performed somewhat better than the course-specific models,with two models having AUC of 0.70 and 0.78,which are considered"fair"predictive accuracy.Conclusion:Attrition rate was similar between 28-day and 80-day courses.In comparison to the 80-day full course,the 28-day course had a lower rate of injury but a higher number of injuries per person-year and of fitness test failure.These findings suggest fitness level at the commencement of training is a critically important factor to consider when designing the course curriculum,particularly short courses.展开更多
Ferroptosis has emerged as a crucial regulated cell death involved in a variety of physiological processes or pathological diseases,such as tumor suppression.Though initially being found from anticancer drug screening...Ferroptosis has emerged as a crucial regulated cell death involved in a variety of physiological processes or pathological diseases,such as tumor suppression.Though initially being found from anticancer drug screening and considered not essential as apoptosis for growth and development,numerous studies have demonstrated that ferroptosis is tightly regulated by key genetic pathways and/or genes,including several tumor suppressors and oncogenes.In this review,we introduce the basic concepts of ferroptosis,characterized by the features of non-apoptotic,iron-dependent,and overwhelmed accumulation of lipid peroxides,and the underlying regulated circuits are considered to be pro-ferroptotic pathways.Then,we discuss several established lipid peroxidation defending systems within cells,including SLC7A11/GPX4,FSP1/CoQ,GCH1/BH4,and mitochondria DHODH/CoQ,all of which serve as anti-ferroptotic pathways to prevent ferroptosis.Moreover,we provide a comprehensive summary of the genetic regulation of ferroptosis via targeting the above-mentioned pro-ferroptotic or anti-ferroptotic pathways.The regulation of proand anti-ferroptotic pathways gives rise to more specific responses to the tumor cells in a contextdependent manner,highlighting the unceasing study and deeper understanding of mechanistic regulation of ferroptosis for the purpose of applying ferroptosis induction in cancer therapy.展开更多
With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical aperture.In this paper,a planar deployabl...With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical aperture.In this paper,a planar deployable mechanism is proposed,which can form a flat reflection surface with a small gap between plates.To this end,a novel large-scale two-dimensional deployable nine-grid planar antenna mechanism is designed.First,two antenna folding schemes and four supporting mechanism schemes are proposed.Through comparison analysis,the antenna configuration scheme with the best comprehensive performance is selected.A kinematic model of the deployable mechanism is established,and its kinematic characteristics are analyzed.Then,the correctness of the kinematic model is verified by comparing the analytical and simulation results of the kinematic model.Subsequently,a finite element model of the antenna is developed.Based on the response surface method,the structural parameters of the support rods of the antenna are optimized,and a set of optimized solutions with lightweight and high fundamental frequency characteristics are obtained.Finally,a prototype of the proposed nine-grid planar antenna is fabricated.The feasibility of the deployment principle and the rationality of the designed mechanism are verified by deployment experiments.展开更多
The issues of energy shortage and environmental pollution have accelerated the electrification of construction ma-chinery(CM)industry globally.In China,the amount of electric construction machinery(ECM)has been growin...The issues of energy shortage and environmental pollution have accelerated the electrification of construction ma-chinery(CM)industry globally.In China,the amount of electric construction machinery(ECM)has been growing across the industry.The sales of ECM are estimated to reach 600000 vehicles by the end of 2025,while the total demand for battery power will reach 60 GWh.However,the development of ECM still faces critical challenges including reliable power supply and energy distribution among various components.In this review,we primarily focus on important technological breakthroughs and the difficulties faced by the CM industry in China.An overview of ECM including classification and characteristics is given at the beginning.Next,the selection of key components such as the electric motor and the energy storage units,and the control strategy in the pure electric drive system are discussed.The characteristics of the hybrid electric drive system such as structure design and power matching are analyzed in detail.The battery management system(BMS)is critical to ensure appropriate battery health for reliable power supply.Here,we extensively review technical developments in various BMSs.In addition,we roughly estimate the national total of CM emissions and the potential environmental benefits of employing ECMs in China.Finally,we set out future research directions and industrial development of ECM.展开更多
To understand the relationship between the process-microstructure-mechanical properties of the high-pressure die-casting(HPDC) AE44 magnesium alloy, 3D reconstruction and 2D characterization were carried out on the HP...To understand the relationship between the process-microstructure-mechanical properties of the high-pressure die-casting(HPDC) AE44 magnesium alloy, 3D reconstruction and 2D characterization were carried out on the HPDC castings produced with different process parameters(low slow-shot speed, fast slow-shot speed, solidification pressure). Microstructural characterization revealed that the formation of shrinkage pores are closely related to ESCs, which were mainly controlled by the low slow-shot speed in shot sleeve(ESCs growth time) and fast slow-shot speed into the die cavity(distribution of ESCs). In addition, solidification pressure can significantly reduce the shrinkage porosity in the center by improving the feeding capacity of liquid metal. Tensile fracture revealed that the tearing ridge is mainly evolved from the slip band of ESCs. The quantity and distribution of ESCs determine the fracture mode of castings. The relationship between mechanical properties of castings and the morphology of ESCs and porosity is also statistically discussed.展开更多
Corrosion leakage occurred in the 14th tube bundle in the first row of a residual oil hydrotreating air cooler after operating for two years.The failure location was 0.5 m from the outlet header box.In this paper,the ...Corrosion leakage occurred in the 14th tube bundle in the first row of a residual oil hydrotreating air cooler after operating for two years.The failure location was 0.5 m from the outlet header box.In this paper,the erosion corrosion of the air cooler tube bundle was investigated by experimental and numerical methods.Visual inspection,scanning electron microscopy(SEM),and X-ray diffraction(XRD)experiments were performed,and the failure morphology and material composition confirmed that the damage was caused by erosion corrosion.The shear stress transport k–ωturbulence model(SST-k–ω)was then used to investigate the flow and erosion corrosion characteristics,combined with mass transfer,corrosion rate,and ionization equilibrium models.The numerical simulation results revealed that the water phase volume fraction increased with flow and heat transfer in the fluid,which increased the mass flow rate and concentration of hydrogen sulfide.The mass transfer coefficient and corrosion rate were proposed as important parameters to characterize erosion corrosion.Moreover,the local concentration of wall shear stress was found to increase the risk of erosion corrosion.The predicted high-risk area was consistent with the actual failure area,which verified that this failure incident was attributable to erosion corrosion by the water phase.展开更多
基金Provincial Key Research and Development Plan of Heilongjiang(2022ZX04A01)。
文摘The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and X-ray diffractometer,combined with software tools like Matlab,Image-Pro Plus,and CHANNEL5,the influence mechanism of rare earth element addition on the strength,toughness,and inclusions of deposited metal in 1000 MPa grade high-strength steel was investigated.The results indicate that the incorporation of rare earth elements enhances the weldability of the welding materials.With the addition of rare earth elements,the tensile strength of the deposited metal increases from 935 MPa to 960 MPa.However,further addition leads to a decrease in tensile strength,while the yield strength continuously increases by 8.5%-17.2%.The addition of appropriate amounts of rare earth elements results in an increase in acicular ferrite and retained austenite content,as well as grain refinement in the deposited metal,leading to 8.5%-24.3% and 15.6%-42.2% enhancement in impact energy at−40℃ and−60℃,respectively.Additionally,the proper addition of rare earth elements modifies the inclusions and generates fine and dispersed composite inclusions that bond better with the matrix,thereby optimizing the properties of the deposited metal through various mechanisms.Adding an appropriate amount of rare earth elements can significantly enhance the properties of the deposited metal in 1000 MPa grade high-strength steel,and improve the match between high strength and toughness,meeting the demands for high-strength steel used in hydropower applications.
基金National Natural Science Foundation of China(52071126)Natural Science Foundation of Tianjin City,China(22JCQNJC01240)+2 种基金Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1009G)Special Funds for Science and Technology Innovation in Hebei(2022X19)Anhui Provincial Natural Science Foundation(2308085ME135)。
文摘Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.
基金financed by Guangxi Transportation Science and Technology Achievement Promotion Project(GXJT-YFZX-2024-01-01):Intelligent Detection and Data Application R&D Center for Guangxi Transportation Industry.
文摘Ultra-high performance fiber-reinforced concrete (UHPFRC) has received extensive attention from scholars and engineers due to its excellent mechanical properties and durability. However, there is a mutually restrictive relationship between the workability and mechanical properties of UHPFRC. Specifically, the addition of fibers will affect the workability of fresh UHPFRC, and the workability of fresh UHPFRC will also affect the dispersion and arrangement of fibers, thus significantly influencing the mechanical properties of hardened UHPFRC. This paper first analyzes the research status of UHPFRC and the relationship between its workability and mechanical properties. Subsequently, it outlines the test methods and indicators of UHPFRC workability, including fluidity, slump, V-funnel passing time, and rheology. Then, it reviews the impacts of metal fibers, synthetic fibers, hybrid fibers, and other fibers on the workability and mechanical properties of UHPFRC, and presents a reasonable range of fiber dosage for workability and mechanical properties. Key findings include: (1) Steel fibers within 1%–2% volume optimize workability-mechanical balance, while exceeding 2.5% reduces compressive strength by 7%–30%;(2) Hybrid steel-polypropylene fibers enhance toughness by 65%;(3) Fiber orientation control via rheology-modifying admixtures improves flexural strength by up to 64%. This review establishes a fiber factor (V·L/D) for predictive mix design, advancing beyond empirical approaches in prior studies.
基金supported in part by the National Natural Science Foundation of China under Grant 62071094in part by the National Key Laboratory of Wireless Communications Foundation under Grant IFN202402in part by the Postdoctoral Fellowship Program(Grade C)of China Postdoctoral Science Foundation under Grant GZC20240217.
文摘To guarantee secure communication against eavesdropping and malicious attack,an artificial noise(AN)-aided frequency-hopping(FH)architecture is adopted in this article.But the inevitable time misalignment between the received signal and locally reconstructed AN will deteriorate the AN cancellation performance,yielding significant secrecy degradation at the FH receiver.In view of this,first,the AN cancellation performance under time misalignment is evaluated via signal to AN-plus-noise ratio,and the system secrecy is analyzed via secrecy rate.Then,to mitigate the performance degradation raised by time misalignment,the transmitting power allocation scheme for AN and confidential signal(CS)is optimized,and the optimal hopping period is designed.Notably,the obtained conclusions in both the performance evaluation and transmitter optimization sections hold no matter whether the eavesdropper can realize FH synchronization or not.Simulations verify that time misalignment will raise non-negligible performance degradation.Besides,the power ratio of AN to CS should decrease as time misalignment increases,and for perfect time synchronization,the transmitting power of AN and CS should be equivalent.In addition,a longer hopping period is preferred for secrecy enhancement when time misalignment gets exacerbated.
基金the financial support by the National Natural Science Foundation of China(52378440,42477143)the Key Science and Technology Program in the Transportation Industry(2022-MS1-032,2022-MS5-125)+2 种基金the Postgraduate Scientific Research Innovation Project of Hunan Province(CX20251302)the Science and Technology Innovation Program of Hunan Province(2024RC3166)the Guangxi Key Research and Development Program(AB23075184)。
文摘Carbonaceous mudstone is a potential embankment filler in mountainous regions with limited high-quality materials;however,its engineering performance in highway embankments under complex environmental conditions remains poorly understood.This study aimed to investigate the mechanical properties and failure mechanisms of carbonaceous mudstone filler under different temperature-moisture coupled conditions.Triaxial shear tests were conducted under four temperaturemoisture coupled conditions:dry-heat to dry-cold(DHDC),wet-cold to wet-heat(WCWH),dry-cold to wet-heat(DCWH),and dry-heat to wet-cold(DHWC).The effects of these conditions on the strength characteristics,relative breakage ratio,failure mode,and microscopic morphology were examined.A segmented prediction model based on the DuncanChang model was applied to validate the experimental results under the DHWC condition.The failure mechanisms under different conditions were also analyzed.The results indicate that the degradation of carbonaceous mudstone increases in the following order:DHDC,WCWH,DCWH,and DHWC.Under the DHDC condition,the stress-strain curves exhibit strain-softening behavior,while other conditions show strain-hardening behavior,with peak deviatoric stress occurring at 2%and 4%axial strains,respectively.The shear strength decreases by up to 40%under the DHWC condition but remains nearly unchanged under the DHDC condition,showing a positive correlation with particle breakage.As the number of cycles increases,the failure surfaces gradually move downward.Higher confining pressure shifts failure mode from shear failure to shear slip or localized compression,and eventually to overall compression or expansion failure.The modified Duncan-Chang model accurately predicts the experimental results.These findings provide important guidance for the application of carbonaceous mudstone filler in highway embankment construction in humid mountainous regions.
基金supported by the Major Program of National Natural Science Foundation of China (No. 52193268013)。
文摘Anaerobic digestion (AD) with thermal hydrolysis (TH) pretreatment is a promising process for excess sludge treatment,while there lacks of the knowledge from full-scale process about the impact of sludge composition and characteristics on microbial community and performance.The sludge physiochemical indices,microbial community and performance data of four full-scale TH-AD plants were characterized,and their relationships was elucidated.The four plants were operated under almost similar total organic loading rate (OLR)but their methanogenesis performance differentiate into two groups,namely superior group(SupG) and the inferior group (Inf G).In both groups,TH effectively solubilized particulate organic compounds,meanwhile raised the ammonia nitrogen (NH_(4)^(+)-N) and volatile fatty acid (VFA) concentration.Compared with the Sup G,thermal hydrolyzed sludge of Inf G had higher level of VFAs,NH_(4)^(+)-N and total chemical oxygen demand (t COD),which showed higher inhibition effect on microbes,leading to a community with lower diversity,lower abundance of carbohydrate degrading functional guild,higher protein degrading one,and methanogens that adapted to limited substrates,and further declined the methane production rate.Thus,it was recommended that OLR alone was not sufficient for controlling the system in design and operation,the concentration of VFAs,NH_(4)^(+)-N and t COD should be equally considered.Their higher concentration,together with the higher abundance of Defluviitoga and Proteiniphilum were recommended as indicators for inferior running condition.Our results proposed that microbial communities played a role of bridge between environmental factors and performance,provided implications for engineering ecology and operational regulation for full-scale sludge TH-AD process.
基金supported by the technology development fund of Beijing Research Institute of Mechanical&Electrical Technology Co.,Ltd.,CAM,Construction of Innovation Leading Talents and Innovation Team of China Academy of Machinery Science and Technology Group:Vacuum forming technology and equipment innovation team.
文摘Static recrystallization(SRX)characteristics of a powder metallurgy superalloy were investigated by isothermal compression at 1080–1170℃ under strain rates of 0.01–0.1 s^(−1),strains of 0.1,0.22,or 0.5,and holding time of 0–300 s.The impacts of temperature,strain rate,holding time,and strain on the SRXed grain size,volume fraction,and microtexture were explored by electron backscatter diffraction technique.It was found that temperature played a key role in these processes.As SRX progressed,the<110>fiber parallel to the axis compression direction gradually weakened and was replaced by the<001>fiber because<001>was the preferred recrystallization orientation and grain growth direction for the Ni-based superalloy.Moreover,high temperatures and low strain rates promoted the formation of the<001>fiber.Three nucleation mechanisms during SRX process were found:grain boundary bulging,primary twin assistance,and subgrain coalescence.Grain boundary bulging occurred under all process conditions;however,at low temperatures and high strain rates,the latter two mechanisms could provide additional nucleation modes.In addition,SRX size and volume fraction models were established.
文摘The dual-rotor structure serves as the primary source of vibration in aero-engines. Understanding itsdynamical model and analyzing dynamic characteristics, such as critical speed and unbalanced response, arecrucial for rotor system dynamics. Previous work introduced a coaxial dual-rotor-support scheme for aeroengines,and a physical model featuring a high-speed flexible inner rotor with a substantial length-to-diameter ratiowas designed. Then a finite element (FE) dynamic model based on the Timoshenko beam elements and rigid bodykinematics of the dual-rotor system is modeled, with the Newmark method and Newton–Raphson method used forthe numerical calculation to study the dynamic characteristics of the system. Three different simulation models,including beam-based FE (1D) model, solid-based FE (3D) model, and transfer matrix model, were designed tostudy the characteristics of mode and the critical speed characteristic of the dual-rotor system. The unbalancedresponse of the dual-rotor system was analyzed to study the influence of mass unbalance on the rotor system. Theeffect of different disk unbalance phases and different speed ratios on the dynamic characteristics of the dual-rotorsystem was investigated in detail. The experimental result shows that the beam-based FE model is effective andsuitable for studying the dual-rotor system.
基金financially supported by the National Natural Science Foundation of China(No.52075391).
文摘The new energy vehicle body composed of multi-metals requires a synchronous chemical conversion coating to exhibit excellent corrosion resistance.Herein,we prepared a titanium/zirconium/water-based oligomeric epoxy silane composite chemical conversion coating on multi-metals,and conducted an investigation into its electrochemical behavior and micro-zone structural characteristics upon immersion in a 3.5%NaCl solution.The electrochemical results combined with characterization results revealed that the corrosion evolution characteristics of the composite coatings could be categorized into three stages of mild corrosion,synergistic protection,and substrate damage.Besides,Si-OH groups interact with Me-OH at the defect on the multi-metal surface to form an organic monolayer coating.This organic monolayer coating,in conjunction with the synergistic inorganic conversion layer comprising Al_(2)O_(3),TiO_(2),2H_(2)O,ZrO_(2),2H_(2)O,effectively cooperates with the corrosion products to hinder the erosion by the corrosive medium and suppresses the progression of the anodic reaction.
基金supported by the Young Elite Scientists Sponsorship Program by CAST(Grant No.2023QNRC001).
文摘Lithium-ion batteries are used extensively in civil,military,and aerospace applications because of their high energy and power density.However,in practical applications,these batteries may encounter extreme cases characterized by transient high impacts,which impose stringent requirements on their safety and reliability.In recent years,the failure mechanism associated with the short-circuiting of lithium-ion-battery separators under high dynamic impacts has been investigated thoroughly.Based on the separator impact failure mechanism,we prepared a porous polymer polyvinylidene fluoride(PVDF)separator by doping gas-phase SiO_(2)(fumed silica)additive.The gas-phase SiO_(2)has a unique three-dimensional cluster structure,which is impact resistant.The impact resistance of the battery separator was tested using a highdynamic-impact system.The voltage drop of the battery with 3%SiO_(2)content was 33.04%of that of the original PVDF battery.Material characterization of the separator was further explored by scanning electron microscope,static compression,and pore-size adsorption tests.The SiO_(2)with a special cluster structure was distributed uniformly on the surface of the separator and embedded in the inner walls of the pores.Under static compression,the current of the SiO_(2)-PVDF separator with 3%content rose at a lower rate than that of the PVDF separator,with a minimum current of 1.04 mA.After adding SiO_(2),the separator pore size increased from 5 to 20 nm.Also,we used COMSOL to conduct impact simulations of different separators.The calculation results showed that the deformation(9.98%)and internal electrode current(0.018 A)of the SiO_(2)-PVDF lithium-ion battery were lower than the deformation(23.09%)and internal electrode current(0.049 A)of the PVDF lithium-ion battery.The SiO_(2)-doped composite polymer separator with a special cluster structure plays a crucial role in enhancing the impact resistance of lithium-ion batteries.
基金the financial support by the National Natural Science Foundation of China(Grant No.52108397)“Xiaohe”Science and Technology Talent Special Project(Grant No.2024 TJ-X06)Water Resources Science and Technology Project of Hunan Province(Grant No.XSKJ2023059-41).
文摘Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.
基金funded by The National Key R&D Program of China(2023YFC2205600)Open Project of Space Structure and Mechanism Technology Laboratory of China Aerospace Science and Technology Group Co.,Ltd.(YY-F805202312005)+1 种基金HIT Youth Scientist Laboratory Project,Postdoctoral Fellowship Program of CPSF(GZB20230259)the China Postdoctoral Science Foundation(2023TQ0133)(2023M731288).
文摘The gecko's feet possess unique microstructures that enable strong adhesive forces when interacting with various surfaces.Understanding the interfacial forces generated by these microstructures is crucial for deciphering their adhesion mechanism.This study developed a contact mechanics model based on van der Waals forces and frictional self-locking effects,incorporating both the spatular pad and spatular shaft of the gecko’s foot microstructures.Building on this foundation,a discrete element simulation model was established using the bonding method to replicate the contact between the gecko's spatula and different surfaces.The dynamic adhesion and detaching processes under normal and tangential external forces were simulated,allowing for the analysis of variation curves of normal and tangential adhesion forces at different detaching angles.This provided insights into the directional adhesion mechanics of the gecko's spatula.Furthermore,a force measurement system was constructed using a multi-degree-of-freedom nano-manipulator and an atomic force microscope within a scanning electron microscope.This system was used to experimentally test the adhesion characteristics of the gecko’s foot microstructures,validating the accuracy of the proposed adhesion mechanics model.
基金Supported by Natural Science Foundation to Basic Research in Key Areas of Heilongjiang Province of China(Grant No.TD2020E002).
文摘The current research of titanium alloy on friction welding process in the field of aero-engines mainly focuses on the linear friction welding.Compared to the linear friction welding,inertial friction welding of titanium alloy still has important application position in the welding of aero-engine rotating assembly.However,up to now,few reports on inertial friction welding of titanium alloy are found.In this paper,the near-alpha TA19 titanium alloy welded joint was successfully obtained by inertial friction welding(IFW)process.The microstructures and mechanical properties were investigated systematically.Results showed that the refined grains within 15‒20μm and weak texture were found in the weld zone due to dynamic recrystallization caused by high temperature and plastic deformation.The weld zone consisted of acicularα′martensite phase,αp phase and metastableβphase.Most lath-shapedαs andβphase in base metal were transformed into acicular martensiteα′phase and metastableβphase in thermo-mechanically affected zone and heat affected zone.As a result,the microhardness of welded joint gradually decreased from the weld zone to the base metal.Tensile specimens in room temperature and high temperature of 480℃ were all fractured in base metal illustrating that the inertia friction welded TA19 titanium alloy joint owned higher tensile strength compared to the base metal.
基金This work was financially supported by the National Science Found for Distinguished Young Scholars(No.51525503).
文摘Digital patternless freeze-casting technology is a new approach for obtaining frozen sand moulds using digital milling technology. The change law of tensile strength and air permeability of frozen sand moulds (100-mesh and 200-mesh silica sand, and zircon sand moulds) under different freezing temperatures and water contents was studied. Results show that with the decrease of freezing temperature and the increase of water contents, the tensile strength and air permeability of the sand moulds are gradually improved. Meanwhile, computed tomography technology was used to characterize the shape and size of the water film between the sand particles mixed with 4wt.% water. The results show that in silica sand moulds, the form of water film is lumpy, and 200-mesh silica sand moulds have more water films and higher proportion of small-sized water films than 100-mesh silica sand moulds, while in zircon sand moulds, the form of water film is membranous. At the same freezing temperature and water content, the tensile strength of zircon sand mould is the highest, and 100-mesh silica sand mould is the lowest. A comparative solidification experiment of A356 aluminum alloy was carried out in frozen sand mould and resin sand mould. The results show that the primary α-Al phase appears in the form of equiaxed and eutectic silicon phase is needle-like in freezing sand mould casting, but the primary α-Al phase grows in the form of dendrites, and the eutectic silicon phase is coarse needle-like in the resin sand mould casting. The difference of microstructure is caused by the different cooling rate. The cooling rate of A356 aluminum alloy in frozen sand mould is higher than that in resin sand mould.
文摘Background:Attrition rate in new army recruits is higher than in incumbent troops.In the current study,we identified the risk factors for attrition due to injuries and physical fitness failure in recruit training.A variety of predictive models were attempted.Methods:This retrospective cohort included 19,769 Army soldiers of the Australian Defence Force receiving recruit training during a period from 2006 to 2011.Among them,7692 reserve soldiers received a 28-day training course,and the remaining 12,077 full-time soldiers received an 80-day training course.Retrieved data included anthropometric measures,course-specific variables,injury,and physical fitness failure.Multivariate regression was used to develop a variety of models to predict the rate of attrition due to injuries and physical fitness failure.The area under the receiver operating characteristic curve was used to compare the performance of the models.Results:In the overall analysis that included both the 28-day and 80-day courses,the incidence of injury of any type was 27.8%.The 80-day course had a higher rate of injury if calculated per course(34.3%vs.17.6%in the 28-day course),but lower number of injuries per person-year(1.56 vs.2.29).Fitness test failure rate was significantly higher in the 28-day course(30.0%vs.12.1%).The overall attrition rate was 5.2%and 5.0%in the 28-day and 80-day courses,respectively.Stress fracture was common in the 80-day course(n=44)and rare in the 28-day course(n=1).The areas under the receiver operating characteristic curves for the course-specific predictive models were relatively low(ranging from 0.51 to 0.69),consistent with"failed"to"poor"predictive accuracy.The course-combined models performed somewhat better than the course-specific models,with two models having AUC of 0.70 and 0.78,which are considered"fair"predictive accuracy.Conclusion:Attrition rate was similar between 28-day and 80-day courses.In comparison to the 80-day full course,the 28-day course had a lower rate of injury but a higher number of injuries per person-year and of fitness test failure.These findings suggest fitness level at the commencement of training is a critically important factor to consider when designing the course curriculum,particularly short courses.
基金the funding support from National Natural Science Foundation of China(82103272 to Y.Zhang)Xi’an Jiaotong University(xtr042021011 to Y.Zhang)+1 种基金Department of Science and Technology of Shaanxi Province(2022KW-48 to J Chen)supported by Top Young Talents Programme at Xi’an Jiaotong University。
文摘Ferroptosis has emerged as a crucial regulated cell death involved in a variety of physiological processes or pathological diseases,such as tumor suppression.Though initially being found from anticancer drug screening and considered not essential as apoptosis for growth and development,numerous studies have demonstrated that ferroptosis is tightly regulated by key genetic pathways and/or genes,including several tumor suppressors and oncogenes.In this review,we introduce the basic concepts of ferroptosis,characterized by the features of non-apoptotic,iron-dependent,and overwhelmed accumulation of lipid peroxides,and the underlying regulated circuits are considered to be pro-ferroptotic pathways.Then,we discuss several established lipid peroxidation defending systems within cells,including SLC7A11/GPX4,FSP1/CoQ,GCH1/BH4,and mitochondria DHODH/CoQ,all of which serve as anti-ferroptotic pathways to prevent ferroptosis.Moreover,we provide a comprehensive summary of the genetic regulation of ferroptosis via targeting the above-mentioned pro-ferroptotic or anti-ferroptotic pathways.The regulation of proand anti-ferroptotic pathways gives rise to more specific responses to the tumor cells in a contextdependent manner,highlighting the unceasing study and deeper understanding of mechanistic regulation of ferroptosis for the purpose of applying ferroptosis induction in cancer therapy.
基金supported by the National Natural Science Foundation of China(No.52075467).
文摘With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical aperture.In this paper,a planar deployable mechanism is proposed,which can form a flat reflection surface with a small gap between plates.To this end,a novel large-scale two-dimensional deployable nine-grid planar antenna mechanism is designed.First,two antenna folding schemes and four supporting mechanism schemes are proposed.Through comparison analysis,the antenna configuration scheme with the best comprehensive performance is selected.A kinematic model of the deployable mechanism is established,and its kinematic characteristics are analyzed.Then,the correctness of the kinematic model is verified by comparing the analytical and simulation results of the kinematic model.Subsequently,a finite element model of the antenna is developed.Based on the response surface method,the structural parameters of the support rods of the antenna are optimized,and a set of optimized solutions with lightweight and high fundamental frequency characteristics are obtained.Finally,a prototype of the proposed nine-grid planar antenna is fabricated.The feasibility of the deployment principle and the rationality of the designed mechanism are verified by deployment experiments.
基金Project supported by the National Key R&D Program of China(No.2019YFB2004604)the National Natural Science Foundation of China(Nos.52075481 and 52075477)+2 种基金the Zhejiang Provincial Natural Science Foundation of China(No.LR19E050002)the Key R&D Program of Zhejiang Province(No.2020C01152)and the“Innovation 2025”Major Project of Ningbo(No.2020Z110),China。
文摘The issues of energy shortage and environmental pollution have accelerated the electrification of construction ma-chinery(CM)industry globally.In China,the amount of electric construction machinery(ECM)has been growing across the industry.The sales of ECM are estimated to reach 600000 vehicles by the end of 2025,while the total demand for battery power will reach 60 GWh.However,the development of ECM still faces critical challenges including reliable power supply and energy distribution among various components.In this review,we primarily focus on important technological breakthroughs and the difficulties faced by the CM industry in China.An overview of ECM including classification and characteristics is given at the beginning.Next,the selection of key components such as the electric motor and the energy storage units,and the control strategy in the pure electric drive system are discussed.The characteristics of the hybrid electric drive system such as structure design and power matching are analyzed in detail.The battery management system(BMS)is critical to ensure appropriate battery health for reliable power supply.Here,we extensively review technical developments in various BMSs.In addition,we roughly estimate the national total of CM emissions and the potential environmental benefits of employing ECMs in China.Finally,we set out future research directions and industrial development of ECM.
基金financially supported by the Fundamental Research Funds for the Central Universities (M22JBMC0060)the National Natural Science Foundation of China (No.52175284)the State Key Lab of Advanced Metals and Materials (No.2021-ZD08)。
文摘To understand the relationship between the process-microstructure-mechanical properties of the high-pressure die-casting(HPDC) AE44 magnesium alloy, 3D reconstruction and 2D characterization were carried out on the HPDC castings produced with different process parameters(low slow-shot speed, fast slow-shot speed, solidification pressure). Microstructural characterization revealed that the formation of shrinkage pores are closely related to ESCs, which were mainly controlled by the low slow-shot speed in shot sleeve(ESCs growth time) and fast slow-shot speed into the die cavity(distribution of ESCs). In addition, solidification pressure can significantly reduce the shrinkage porosity in the center by improving the feeding capacity of liquid metal. Tensile fracture revealed that the tearing ridge is mainly evolved from the slip band of ESCs. The quantity and distribution of ESCs determine the fracture mode of castings. The relationship between mechanical properties of castings and the morphology of ESCs and porosity is also statistically discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.51876194,U1909216,and 52176048)the Fundamental Research Funds of Zhejiang Sci-Tech University(Grant No.2021Q020).
文摘Corrosion leakage occurred in the 14th tube bundle in the first row of a residual oil hydrotreating air cooler after operating for two years.The failure location was 0.5 m from the outlet header box.In this paper,the erosion corrosion of the air cooler tube bundle was investigated by experimental and numerical methods.Visual inspection,scanning electron microscopy(SEM),and X-ray diffraction(XRD)experiments were performed,and the failure morphology and material composition confirmed that the damage was caused by erosion corrosion.The shear stress transport k–ωturbulence model(SST-k–ω)was then used to investigate the flow and erosion corrosion characteristics,combined with mass transfer,corrosion rate,and ionization equilibrium models.The numerical simulation results revealed that the water phase volume fraction increased with flow and heat transfer in the fluid,which increased the mass flow rate and concentration of hydrogen sulfide.The mass transfer coefficient and corrosion rate were proposed as important parameters to characterize erosion corrosion.Moreover,the local concentration of wall shear stress was found to increase the risk of erosion corrosion.The predicted high-risk area was consistent with the actual failure area,which verified that this failure incident was attributable to erosion corrosion by the water phase.
