The coupling effect of dual-parallel rotor connected stator permanent magnet synchronous motor not only affects the magnetic field in the coupling area, but also generates an additional magnetic field in the uncoupled...The coupling effect of dual-parallel rotor connected stator permanent magnet synchronous motor not only affects the magnetic field in the coupling area, but also generates an additional magnetic field in the uncoupled area.The characteristics of the additional magnetic field and its influence on electromagnetic torque are studied in this paper.The topology and parameters of motor are described briefly.The existence of additional magnetic field is proved by the simulation models under two boundary conditions, and its characteristics and source are analyzed. The analytical model is established, and the influence of key parameters on the additional magnetic field is discussed. On this basis, the influence of the additional magnetic field on the electromagnetic torque of the motor is studied, and the analytical expression of the additional torque is constructed.The fluctuation rule is analyzed, and the additional magnetic field separation model is proposed. The theoretical analysis and simulation results reveal and improve the internal mechanism of reducing motor torque ripple by optimizing the duty angle and coupling distance. Finally, a prototype test platform is built to verify the correctness of the proposed theory and the accuracy of the simulation model.展开更多
This study explores the multifaceted dynamics of silence among Englishas an Additional Language(EAL)learners in Grade 1 STEM(Science,Technology,Engineering,and Mathematics)classrooms throughnarrative inquiry methodolo...This study explores the multifaceted dynamics of silence among Englishas an Additional Language(EAL)learners in Grade 1 STEM(Science,Technology,Engineering,and Mathematics)classrooms throughnarrative inquiry methodology.Drawing on four weeks of teachingpracticum observations,the findings reveal that silence operates not asdisengagement but as cognitive engagement,cultural negotiation,identity management,and emotional self-regulation.Classroom silence,influenced by cultural communication norms,strategic agency,andemotional safety needs,highlights the inadequacy of traditional modelsof verbal participation.By positioning silence as a legitimate form ofparticipation,the study argues for culturally sustaining pedagogicalpractices that validate multimodal and non-verbal student contributions.Insights are also connected to challenges and opportunities in China'semerging inquiry-based STEM education efforts.This research advancesunderstandings of inclusive participation and offers pedagogicalrecommendations for linguistically diverse classrooms.展开更多
The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely ...The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely applied to address issues such as seepage,leakage,and alignment correction in shield tunnels.This study investigates the additional stress induced by grouting in silty soil layers,using cement-based grouts with different water-to-cement ratios and polyurethane-modified cement-based materials.Results show that additional stress decreases with depth and is more influenced by horizontal distance from the grouting point.In staged grouting,the first injection phase contributes about 50%of the peak additional stress.A lower water-to-cement ratio(e.g.,0.6)increases additional stress but reduces grout flowability,while a higher ratio improves diffusion but increases the risk of grout loss.(≥1.0)The polyurethane-modified cement-based material enhances stress transfer performance,increasing peak additional stress by approximately 10%.These findings provide theoretical guidance for optimizing material selection and grouting design in metro tunnel repair within silty soil layers.展开更多
Refractory metals,including tungsten(W),tantalum(Ta),molybdenum(Mo),and niobium(Nb),play a vital role in industries,such as nuclear energy and aerospace,owing to their exceptional melting temperatures,thermal durabili...Refractory metals,including tungsten(W),tantalum(Ta),molybdenum(Mo),and niobium(Nb),play a vital role in industries,such as nuclear energy and aerospace,owing to their exceptional melting temperatures,thermal durability,and corrosion resistance.These metals have body-centered cubic crystal structure,characterized by limited slip systems and impeded dislocation motion,resulting in significant low-temperature brittleness,which poses challenges for the conventional processing.Additive manufacturing technique provides an innovative approach,enabling the production of intricate parts without molds,which significantly improves the efficiency of material usage.This review provides a comprehensive overview of the advancements in additive manufacturing techniques for the production of refractory metals,such as W,Ta,Mo,and Nb,particularly the laser powder bed fusion.In this review,the influence mechanisms of key process parameters(laser power,scan strategy,and powder characteristics)on the evolution of material microstructure,the formation of metallurgical defects,and mechanical properties were discussed.Generally,optimizing powder characteristics,such as sphericity,implementing substrate preheating,and formulating alloying strategies can significantly improve the densification and crack resistance of manufactured parts.Meanwhile,strictly controlling the oxygen impurity content and optimizing the energy density input are also the key factors to achieve the simultaneous improvement in strength and ductility of refractory metals.Although additive manufacturing technique provides an innovative solution for processing refractory metals,critical issues,such as residual stress control,microstructure and performance anisotropy,and process stability,still need to be addressed.This review not only provides a theoretical basis for the additive manufacturing of high-performance refractory metals,but also proposes forward-looking directions for their industrial application.展开更多
Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipmen...Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipment manufacturing,and electronic information.This review provides a comprehensive summary of the progress of AM technology in WC−Co cemented carbides.The fundamental principles and classification of AM techniques are introduced,followed by a categorization and evaluation of the AM techniques for WC−Co cemented carbides.These techniques are classified as either direct AM technology(DAM)or indirect AM technology(IDAM),depending on their inclusion of post-processes like de-binding and sintering.Through an analysis of microstructure features,the most suitable AM route for WC−Co cemented carbide products with controllable microstructure is identified as the indirect AM technology,such as binder jet printing(BJP),which integrates AM with conventional powder metallurgy.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely us...Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely used in fields such as injection molding,die casting,and stamping dies.Adding reinforcing particles into steel is an effective means to improve its performance.Nb/18Ni300 composites were fabricated by LPBF using two kinds of Nb powders with different particle sizes,and their microstructures and properties were studied.The results show that the unmelted Nb particles are uniformly distributed in the 18Ni300 matrix and the grains are refined,which is particularly pronounced with fine Nb particles.In addition,element diffusion occurs between the particles and the matrix.The main phases of the base alloy are α-Fe and a small amount of γ-Fe.With the addition of Nb,part of the α-Fe is transformed into γ-Fe,and unmelted Nb phases appear.The addition of Nb also enhances the hardness and wear resistance of the composites but slightly reduces their tensile properties.After aging treatment,the molten pools and grain boundaries become blurred,grains are further refined,and the interfaces around the particles are thinned.The aging treatment also promotes the formation of reverted austenite.The hardness,ultimate tensile strength,and volumetric wear rate of the base alloy reach 51.9 HRC,1704 MPa,and 17.8×10^(-6) mm^(3)/(N·m),respectively.In contrast,the sample added with fine Nb particles has the highest hardness(56.1 HRC),ultimate tensile strength(1892 MPa)and yield strength(1842 MPa),and the volume wear rate of the sample added with coarse Nb particles is reduced by 90%to 1.7×10^(-6) mm^(3)/(N·m).展开更多
Additive manufacturing(AM),with its high flexibility,cost-effectiveness,and customization,significantly accelerates the advancement of nanogenerators,contributing to sustainable energy solutions and the Internet of Th...Additive manufacturing(AM),with its high flexibility,cost-effectiveness,and customization,significantly accelerates the advancement of nanogenerators,contributing to sustainable energy solutions and the Internet of Things.In this review,an in-depth analysis of AM for piezoelectric and triboelectric nanogenerators is presented from the perspectives of fundamental mechanisms,recent advancements,and future prospects.It highlights AM-enabled advantages of versatility across materials,structural topology optimization,microstructure design,and integrated printing,which enhance critical performance indicators of nanogenerators,such as surface charge density and piezoelectric constant,thereby improving device performance compared to conventional fabrication.Common AM techniques for nanogenerators,including fused deposition modeling,direct ink writing,stereolithography,and digital light processing,are systematically examined in terms of their working principles,improved metrics(output voltage/current,power density),theoretical explanation,and application scopes.Hierarchical relationships connecting AM technologies with performance optimization and applications of nanogenerators are elucidated,providing a solid foundation for advancements in energy harvesting,self-powered sensors,wearable devices,and human-machine interaction.Furthermore,the challenges related to fabrication quality,cross-scale manufacturing,processing efficiency,and industrial deployment are critically discussed.Finally,the future prospects of AM for nanogenerators are explored,aiming to foster continuous progress and innovation in this field.展开更多
The strength-ductility trade-off in magnesium alloys remains a critical challenge urgently requiring resolution in their engineering applications.In this study,both mechanical and corrosion properties are enhanced in ...The strength-ductility trade-off in magnesium alloys remains a critical challenge urgently requiring resolution in their engineering applications.In this study,both mechanical and corrosion properties are enhanced in extruded Mg-Y-Nd-Zr alloys by Sm addition.Sm promotes dynamic recrystallization,activates non-basal slip systems and weakens basal texture intensity,leading to the sub-grain lamellar structure and rare earth texture.The EWS2 alloy exhibits an outstanding combination of high yield strength(328 MPa)and ductility(15.1%).Furthermore,the fragmented second phases in the Sm-containing alloy are uniformly distributed,reducing the subsequent corrosion driving force after micro-galvanic corrosion and facilitating the growth of a more passivating and compact corrosion film.These combined effects contribute to the lowest degradation rate in the EWS2 alloy.This study demonstrates the correlation between microstructure and properties in Sm-containing WE series alloys,providing insights for the design of other high performance magnesium alloys.展开更多
Achieving simultaneous enhancement of crystallinity and optimal domain size remains a fundamental challenge in organic photovoltaics(OPVs),where conventional crystallization strategies often trigger excessive aggregat...Achieving simultaneous enhancement of crystallinity and optimal domain size remains a fundamental challenge in organic photovoltaics(OPVs),where conventional crystallization strategies often trigger excessive aggregation of small-molecule acceptors.This work pioneers a kinetic paradigm for resolving the crystallinity-domain size trade-off in organic photovoltaics through dual-additive-guided stepwise crystallization.By strategically pairing 1,2-dichlorobenzene(o-DCB,low binding energy to Y6)and 1-fluoronaphthalene(FN,high binding energy),we achieve temporally decoupled crystallization control:o-DCB first mediates donor-acceptor co-crystallization during film formation,constructing a metastable network,whereupon FN induces confined Y6 crystallization within this framework during thermal annealing,refining nanostructure without over-aggregation.Morphology studies reveal that this synergy enhances crystallinity of(100)diffraction peaks by 21%–10%versus single-additive controls(o-DCB/FN alone),while maintaining optimal domain size.These morphological advantages yield balanced carrier transport(μh/μe=1.23),near-unity exciton dissociation(98.53%),and a champion power conversion efficiency(PCE)of 18.08%for PM6:Y6,significantly surpassing single-additive devices(o-DCB:17.20%;FN:17.53%).Crucially,the dual-additive strategy demonstrates universal applicability across diverse active layer systems,achieving an outstanding PCE of 19.27%in PM6:L8-BO-based devices,thereby establishing a general framework for morphology control in high-efficiency OPVs.展开更多
Functionally graded cellular structures(FGCSs)have a multitude of applications to a wide range of industries.Utilising the ever-progressing technology of additive manufacturing(AM),FGCSs can be applied to control mate...Functionally graded cellular structures(FGCSs)have a multitude of applications to a wide range of industries.Utilising the ever-progressing technology of additive manufacturing(AM),FGCSs can be applied to control material grading and achieve the desired mechanical properties.The current study explores the design and optimisation of FGCSs for AM,with a focus on improving the compression and impact performance of below knee(BK)prosthetic limbs made of thermoplastic polyurethane(TPU).A multiscale research methodology integrating topology optimization(TO),finite element analysis(FEA),and design of experiments(Do E)was adopted to optimise lattice structures in terms of stiffness and lightweight properties.Two-unit cell designs were considered in the study:Schwarz P gyroid and body-centered cubic(BCC).Response surface methodology(RSM)was implemented to analyse the effect of minimum and maximum cell wall thickness,cell size,and unit cell type on the mechanical performance of TPU FGCS structures.The results indicated that a Schwarz P FGCS structure with cell size,minimum and maximum cell wall thickness of 6,0.9 and 2.8 mm,respectively,could be optimal for a compromise between performance and weight.In this optimized case,stiffness and volume fraction values of 684 N/mm and 0.64 were obtained,respectively.The study also presents a proof-of-concept design for a BK prosthetic damper,highlighting the potential of FGCSs to enhance patient comfort,reduce manufacturing costs,and enable personalised designs through 3D scanning and AM.The obtained results could be a step forward towards the incorporation of AM technologies in prosthetics,offering a pathway to lightweight,cost-effective,and functionally tailored solutions.展开更多
The accelerated shift toward high efficiency and sustainability of the iron and steel is driving the advancement of green,low-carbon and high-quality carbon-containing refractories used for ladles.It is undoubtedly a ...The accelerated shift toward high efficiency and sustainability of the iron and steel is driving the advancement of green,low-carbon and high-quality carbon-containing refractories used for ladles.It is undoubtedly a significant challenge,since the addition of graphite enables refractories to possess superior thermal shock resistance and slag corrosion resistance.To develop low carbon-containing refractories with excellent properties,researchers over the past decades have endeavored to seek additives which can mitigate the adverse effects associated with the decrease in carbon in refractories.These additives can promote the occurrence of various mechanisms about toughening,which depends on inherent properties of additives or reacting with refractories to in situ form different ceramic phases,thereby responding the challenge of low-carbonization in refractories.The latest advances in additives used for low carbon-containing refractories from metal/alloys,oxide,non-oxide and composite powders four aspects were comprehensively overviewed in this review.Oxide additives exhibit a moderate effect on improving thermal shock resistance of refractories but show limited efficacy in improving oxidation resistance.In contrast,non-oxide additives demonstrate remarkable advantages in enhancing both oxidation and slag corrosion resistance.Composite powders combine the advantageous properties of their individual components.These additives often require combination with antioxidants such as Al,Si,or B4C not only to reduce costs but also to achieve optimal properties.Furthermore,future perspectives of these additives are discussed,with the aim of providing useful insights for the continuous progress and practical application of low carbon-containing refractories.展开更多
Achieving high energy and power densities is currently a core challenge in the fabrication of energy storage materials.Although numerous high-capacity materials have been developed,conventional planar electrodes canno...Achieving high energy and power densities is currently a core challenge in the fabrication of energy storage materials.Although numerous high-capacity materials have been developed,conventional planar electrodes cannot achieve high active material loading and efficient ion/electron transport simultaneously.By contrast,three-dimensional(3D)structures have attracted increasing interest because of their capacity to enhance active material utilization,shorten ion and electron transport pathways,reduce interfacial impedance,and provide spatial accommodation for volume expansion.Additive manufacturing(AM)technology effectively fabricates energy-storage materials with 3D structures by accurately constructing complex 3D structures via layer-by-layer deposition.Recent studies have employed AM to construct ordered 3D electrodes that can optimize ion/electron transport,regulate electric field distribution,or improve the electrode-electrolyte interface,thereby contributing to enhanced kinetic performance and cycling stability.This review systematically summarizes the applications of several AM technologies in the fabrication of energy storage materials and analyzes their respective advantages and limitations.Subsequently,the advantages of AM technology in the fabrication of energy storage materials and several major optimization strategies are comprehensively discussed.Finally,the major challenges and potential applications of AM technology in energy storage material optimization are discussed.展开更多
Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-ins...Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-inspired lattice structures feature a square-grid 2D lattice with double diagonal bracings and are additively manufactured via digital light processing(DLP).The collapse strength and energy absorption capacity of sea sponge lattice structures are evaluated under various impact conditions and are compared to those of their constituent square-grid and double diagonal lattices.This study demonstrates that sea sponge lattices can achieve an 11-fold increase in energy absorption compared to the square-grid lattice,due to the stabilizing effect of the double diagonal bracings prompting the structure to collapse layer-bylayer under impact.By adjusting the thickness ratio in the sea sponge lattice,up to 76.7%increment in energy absorption is attained.It is also shown that sea-sponge lattices outperform well-established energy-absorbing materials of equal weight,such as hexagonal honeycombs,confirming their significant potential for impact mitigation.Additionally,this research highlights the enhancements in energy absorption achieved by adding a small amount(0.015 phr)of Multi-Walled Carbon Nanotubes(MWCNTs)to the photocurable resin,thus unlocking new possibilities for the design of innovative lightweight structures with multifunctional attributes.展开更多
The effects of nitrogen(N)deposition on forest soil organic carbon(SOC)are largely unclear,likely due to the divergent responses of particulate(POC)and mineral-associated carbon(MAOC).Conventional understory inorganic...The effects of nitrogen(N)deposition on forest soil organic carbon(SOC)are largely unclear,likely due to the divergent responses of particulate(POC)and mineral-associated carbon(MAOC).Conventional understory inorganic N(UIN)additions neglect canopy processes and the impacts of organic N,potentially misevaluating N deposition effects.This study was conducted in a long-term N addition experiment established in a Moso bamboo forest,which included six treatments combining canopy and understory N additions with organic(urea glycine)and inorganic(NH_(4)NO_(3))forms at a rate of 50 kg N·ha^(-1)·yr^(-1).Litterbags were installed for a two-year decomposition experiment and collected at quarterly intervals,together with concurrent soil sampling under litterbags at 0–10 cm depth.We aimed to examine the effects of canopy vs.understory N addition and organic vs.inorganic N form on soil POC and MAOC concentrations.Our results showed that canopy N additions significantly reduced POC(ased POC-15.9%)but did not affect MAOC(P>0.05).Conversely,understory N additions significantly incre(30.9%)and decreased MAOC(and fungal diversity(FuD),-28.9%).Canopy N additions decreased POC by enhancing peroxidase activity while understory N additions promoted POC by inhibiting litter decomposition.Additionally,understory N addition-induced soil acidification decreased soil Ca^(2+)concentration,microbial carbon use efficiency,and bacterial necromass C,as well as the release of litter water-soluble compounds,thereby inhibiting MAOC.Moreover,nitrogen forms(organic vs.inorganic)had no effect on SOC fractions.Our findings underscore that canopy and understory N addition approaches differentially regulate SOC fractions by altering litter decomposition–microbial–mineral interactions,and the understory approach may overestimate soil POC gain and MAOC loss driven by atmospheric N deposition.展开更多
Human epidermal growth factor receptor 2(HER2)-overexpressing breast cancer is an aggressive phenotype with a poor prognosis,and can easily metastasize and recur.Currently,chemotherapy plus HER2-targeted therapy is th...Human epidermal growth factor receptor 2(HER2)-overexpressing breast cancer is an aggressive phenotype with a poor prognosis,and can easily metastasize and recur.Currently,chemotherapy plus HER2-targeted therapy is the standard systemic treatment for most of these patients.Given that neoadjuvant chemotherapy(NAC)has an efficacy equivalent to that of adjuvant chemotherapy and some additional benefits,many patients,especially those with more advanced tumors,prefer NAC and generally will not receive additional chemotherapy after surgery,irrespective of the pathological response.However,achieving pathological complete response to NAC is strongly correlated with prognosis,especially in triple-negative and HER2-overexpressing breast cancer.Therefore,postoperative treatment of these patients with residual diseases should be optimized to achieve favorable outcomes.The CREATE-X study has confirmed that additional chemotherapy can improve the outcomes of patients with HER2-negative residual disease after NAC.In addition,chemotherapy plays an indispensable role in the treatment of patients who receive surgery directly or who have recurrent lesions.Therefore,can additional chemotherapy improve prognosis of patients with HER2-overexpressing residual breast cancer?At present,no studies have compared the efficacy of additional chemotherapy plus trastuzumab with that of anti-HER2 therapy alone in residual cancer.The KATHERINE study revealed that trastuzumab emtansine(T-DM1)can reduce the risk of recurrence or death by 50%compared with trastuzumab in patients with HER2-positive residual invasive breast cancer after neoadjuvant therapy.T-DM1 is an antibody-drug conjugate of trastuzumab and the cytotoxic agent emtansine,and thus,to an extent,T-DM1 is equivalent to simultaneous application of chemotherapy and targeted therapy.However,high cost and low accessibility limit its use especially in low-and middle-income countries and regions.Hence,we proposed this perspective that additional chemotherapy plus trastuzumab should be given to HER2-overexpressing breast cancer patients with residual disease after NAC to improve their prognosis by discussing that the efficacy of additional chemotherapy plus trastuzumab is superior to that of anti-HER2 therapy alone and not inferior to T-DM1.Additional chemotherapy plus trastuzumab-based HER2-targeted therapy can be used as an alternative regimen to T-DM1 when T-DM1 is unavailable.However,further clinical research on the selection of chemotherapeutic agents is warranted.展开更多
The model of skaft lining under force is developed on the basis of the special stratum condition led to sbart cracking- The model is broken into 3 sub-questions to solve separately. According to the principle of super...The model of skaft lining under force is developed on the basis of the special stratum condition led to sbart cracking- The model is broken into 3 sub-questions to solve separately. According to the principle of superposition and strain compatibility, a second kind Fredholm integral equation is generated.A theoretical solution to vertical additional force on shaft lining is obtained by numerical method to the integral equation.展开更多
The current research of real-time observation for vehicle roll steer angle and compliance steer angle（both of them comprehensively referred as the additional steer angle in this paper） mainly employs the linear vehi...The current research of real-time observation for vehicle roll steer angle and compliance steer angle（both of them comprehensively referred as the additional steer angle in this paper） mainly employs the linear vehicle dynamic model, in which only the lateral acceleration of vehicle body is considered. The observation accuracy resorting to this method cannot meet the requirements of vehicle real-time stability control, especially under extreme driving conditions. The paper explores the solution resorting to experimental method. Firstly, a multi-body dynamic model of a passenger car is built based on the ADAMS/Car software, whose dynamic accuracy is verified by the same vehicle＇s roadway test data of steady static circular test. Based on this simulation platform, several influencing factors of additional steer angle under different driving conditions are quantitatively analyzed. Then ε-SVR algorithm is employed to build the additional steer angle prediction model, whose input vectors mainly include the sensor information of standard electronic stability control system（ESC）. The method of typical slalom tests and FMVSS 126 tests are adopted to make simulation, train model and test model＇s generalization performance. The test result shows that the influence of lateral acceleration on additional steer angle is maximal （the magnitude up to 1°）, followed by the longitudinal acceleration-deceleration and the road wave amplitude （the magnitude up to 0.3°）. Moreover, both the prediction accuracy and the calculation real-time of the model can meet the control requirements of ESC This research expands the accurate observation methods of the additional steer angle under extreme driving conditions.展开更多
An alluvium with a sandy aquifer at the bottom,but lacking an effective impermeable layer between the sandy aquifer and bedrock is referred to as a special alluvial stratum.Impacted by the drainage of the aquifer due ...An alluvium with a sandy aquifer at the bottom,but lacking an effective impermeable layer between the sandy aquifer and bedrock is referred to as a special alluvial stratum.Impacted by the drainage of the aquifer due to mining activities,a shaft wall in this special alluvial stratum will be subject to a downward load by an additional vertical force which must be taken into consideration in the design of the shaft wall.The complexity of interaction between shaft wall and the surrounding walls makes it extremely difficult to determine this additional vertical force.For a particular shaft wall in an extra-thick alluvium and assuming that the friction coefficient between shaft wall and stratum does not change with depth,an analysis of a numerical simulation of the stress within the shaft wall has been carried out.Growth and size of the additional vertical stress have been obtained,based on specific values of the friction coefficient,the modulus of elasticity of the drainage layer and the thickness of the drainage layer.Subsequently, the safety of shaft walls with different structural types was studied and a more suitable structural design,providing an important basis for the design of shaft walls,is promoted.展开更多
基金supported in part by the Natural Science Foundation of Heilongjiang Province under Grant LH2023E084by the National Natural Science Foundation of China under Grant 51777048。
文摘The coupling effect of dual-parallel rotor connected stator permanent magnet synchronous motor not only affects the magnetic field in the coupling area, but also generates an additional magnetic field in the uncoupled area.The characteristics of the additional magnetic field and its influence on electromagnetic torque are studied in this paper.The topology and parameters of motor are described briefly.The existence of additional magnetic field is proved by the simulation models under two boundary conditions, and its characteristics and source are analyzed. The analytical model is established, and the influence of key parameters on the additional magnetic field is discussed. On this basis, the influence of the additional magnetic field on the electromagnetic torque of the motor is studied, and the analytical expression of the additional torque is constructed.The fluctuation rule is analyzed, and the additional magnetic field separation model is proposed. The theoretical analysis and simulation results reveal and improve the internal mechanism of reducing motor torque ripple by optimizing the duty angle and coupling distance. Finally, a prototype test platform is built to verify the correctness of the proposed theory and the accuracy of the simulation model.
文摘This study explores the multifaceted dynamics of silence among Englishas an Additional Language(EAL)learners in Grade 1 STEM(Science,Technology,Engineering,and Mathematics)classrooms throughnarrative inquiry methodology.Drawing on four weeks of teachingpracticum observations,the findings reveal that silence operates not asdisengagement but as cognitive engagement,cultural negotiation,identity management,and emotional self-regulation.Classroom silence,influenced by cultural communication norms,strategic agency,andemotional safety needs,highlights the inadequacy of traditional modelsof verbal participation.By positioning silence as a legitimate form ofparticipation,the study argues for culturally sustaining pedagogicalpractices that validate multimodal and non-verbal student contributions.Insights are also connected to challenges and opportunities in China'semerging inquiry-based STEM education efforts.This research advancesunderstandings of inclusive participation and offers pedagogicalrecommendations for linguistically diverse classrooms.
基金supported by the National Natural Science Foundation of China(No.42477185)Natural Science Foundation of Zhejiang Province(LQ24A020015)+1 种基金Research Achievement Award Cultivation Project of Zhejiang University of Science and Technology(2023JLYB001)the Postgraduate Course Construction Project of Zhejiang University of Science and Technology(2024yjskj05).
文摘The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely applied to address issues such as seepage,leakage,and alignment correction in shield tunnels.This study investigates the additional stress induced by grouting in silty soil layers,using cement-based grouts with different water-to-cement ratios and polyurethane-modified cement-based materials.Results show that additional stress decreases with depth and is more influenced by horizontal distance from the grouting point.In staged grouting,the first injection phase contributes about 50%of the peak additional stress.A lower water-to-cement ratio(e.g.,0.6)increases additional stress but reduces grout flowability,while a higher ratio improves diffusion but increases the risk of grout loss.(≥1.0)The polyurethane-modified cement-based material enhances stress transfer performance,increasing peak additional stress by approximately 10%.These findings provide theoretical guidance for optimizing material selection and grouting design in metro tunnel repair within silty soil layers.
基金National MCF Energy R&D Program(2024YFE03260300)。
文摘Refractory metals,including tungsten(W),tantalum(Ta),molybdenum(Mo),and niobium(Nb),play a vital role in industries,such as nuclear energy and aerospace,owing to their exceptional melting temperatures,thermal durability,and corrosion resistance.These metals have body-centered cubic crystal structure,characterized by limited slip systems and impeded dislocation motion,resulting in significant low-temperature brittleness,which poses challenges for the conventional processing.Additive manufacturing technique provides an innovative approach,enabling the production of intricate parts without molds,which significantly improves the efficiency of material usage.This review provides a comprehensive overview of the advancements in additive manufacturing techniques for the production of refractory metals,such as W,Ta,Mo,and Nb,particularly the laser powder bed fusion.In this review,the influence mechanisms of key process parameters(laser power,scan strategy,and powder characteristics)on the evolution of material microstructure,the formation of metallurgical defects,and mechanical properties were discussed.Generally,optimizing powder characteristics,such as sphericity,implementing substrate preheating,and formulating alloying strategies can significantly improve the densification and crack resistance of manufactured parts.Meanwhile,strictly controlling the oxygen impurity content and optimizing the energy density input are also the key factors to achieve the simultaneous improvement in strength and ductility of refractory metals.Although additive manufacturing technique provides an innovative solution for processing refractory metals,critical issues,such as residual stress control,microstructure and performance anisotropy,and process stability,still need to be addressed.This review not only provides a theoretical basis for the additive manufacturing of high-performance refractory metals,but also proposes forward-looking directions for their industrial application.
基金supported by Major Science and Technology Projects in Fujian Province,China(No.2023HZ021005)State Key Laboratory of Powder Metallurgy,Central South University,ChinaFujian Key Laboratory of Rare-earth Functional Materials,China。
文摘Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipment manufacturing,and electronic information.This review provides a comprehensive summary of the progress of AM technology in WC−Co cemented carbides.The fundamental principles and classification of AM techniques are introduced,followed by a categorization and evaluation of the AM techniques for WC−Co cemented carbides.These techniques are classified as either direct AM technology(DAM)or indirect AM technology(IDAM),depending on their inclusion of post-processes like de-binding and sintering.Through an analysis of microstructure features,the most suitable AM route for WC−Co cemented carbide products with controllable microstructure is identified as the indirect AM technology,such as binder jet printing(BJP),which integrates AM with conventional powder metallurgy.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
基金Key-Area Research and Development Program of Guangdong Province(2023B0909020004)Project of Innovation Research Team in Zhongshan(CXTD2023006)+1 种基金Natural Science Foundation of Guangdong Province(2023A1515011573)Zhongshan Social Welfare Science and Technology Research Project(2024B2022)。
文摘Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely used in fields such as injection molding,die casting,and stamping dies.Adding reinforcing particles into steel is an effective means to improve its performance.Nb/18Ni300 composites were fabricated by LPBF using two kinds of Nb powders with different particle sizes,and their microstructures and properties were studied.The results show that the unmelted Nb particles are uniformly distributed in the 18Ni300 matrix and the grains are refined,which is particularly pronounced with fine Nb particles.In addition,element diffusion occurs between the particles and the matrix.The main phases of the base alloy are α-Fe and a small amount of γ-Fe.With the addition of Nb,part of the α-Fe is transformed into γ-Fe,and unmelted Nb phases appear.The addition of Nb also enhances the hardness and wear resistance of the composites but slightly reduces their tensile properties.After aging treatment,the molten pools and grain boundaries become blurred,grains are further refined,and the interfaces around the particles are thinned.The aging treatment also promotes the formation of reverted austenite.The hardness,ultimate tensile strength,and volumetric wear rate of the base alloy reach 51.9 HRC,1704 MPa,and 17.8×10^(-6) mm^(3)/(N·m),respectively.In contrast,the sample added with fine Nb particles has the highest hardness(56.1 HRC),ultimate tensile strength(1892 MPa)and yield strength(1842 MPa),and the volume wear rate of the sample added with coarse Nb particles is reduced by 90%to 1.7×10^(-6) mm^(3)/(N·m).
基金support from the Research Committee of The Hong Kong Polytechnic University(Project codes:RMJK and 4-ZZSJ)supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.PolyU15212523).
文摘Additive manufacturing(AM),with its high flexibility,cost-effectiveness,and customization,significantly accelerates the advancement of nanogenerators,contributing to sustainable energy solutions and the Internet of Things.In this review,an in-depth analysis of AM for piezoelectric and triboelectric nanogenerators is presented from the perspectives of fundamental mechanisms,recent advancements,and future prospects.It highlights AM-enabled advantages of versatility across materials,structural topology optimization,microstructure design,and integrated printing,which enhance critical performance indicators of nanogenerators,such as surface charge density and piezoelectric constant,thereby improving device performance compared to conventional fabrication.Common AM techniques for nanogenerators,including fused deposition modeling,direct ink writing,stereolithography,and digital light processing,are systematically examined in terms of their working principles,improved metrics(output voltage/current,power density),theoretical explanation,and application scopes.Hierarchical relationships connecting AM technologies with performance optimization and applications of nanogenerators are elucidated,providing a solid foundation for advancements in energy harvesting,self-powered sensors,wearable devices,and human-machine interaction.Furthermore,the challenges related to fabrication quality,cross-scale manufacturing,processing efficiency,and industrial deployment are critically discussed.Finally,the future prospects of AM for nanogenerators are explored,aiming to foster continuous progress and innovation in this field.
基金supported by the National Natural Science Foundation of China(Nos.52201119,52371108)Frontier Exploration Project of Longmen Laboratory,China(No.LMQYTSKT014)The Joint Fund of Henan Science and Technology R&D Plan of China(No.242103810056).
文摘The strength-ductility trade-off in magnesium alloys remains a critical challenge urgently requiring resolution in their engineering applications.In this study,both mechanical and corrosion properties are enhanced in extruded Mg-Y-Nd-Zr alloys by Sm addition.Sm promotes dynamic recrystallization,activates non-basal slip systems and weakens basal texture intensity,leading to the sub-grain lamellar structure and rare earth texture.The EWS2 alloy exhibits an outstanding combination of high yield strength(328 MPa)and ductility(15.1%).Furthermore,the fragmented second phases in the Sm-containing alloy are uniformly distributed,reducing the subsequent corrosion driving force after micro-galvanic corrosion and facilitating the growth of a more passivating and compact corrosion film.These combined effects contribute to the lowest degradation rate in the EWS2 alloy.This study demonstrates the correlation between microstructure and properties in Sm-containing WE series alloys,providing insights for the design of other high performance magnesium alloys.
基金supported by the Shaanxi Provincial High level Talent Introduction Project(5113220044)the Shaanxi Outstanding Youth Project(2023-JC-JQ-33)+8 种基金the Youth Science and Technology Talent Promotion Project of Jiangsu Association for Science and Technology(TJ-2022-088)the Project funded by China Postdoctoral Science Foundation(2023TQ0273,2023TQ0274,2023M742833)the NationalNatural Science Foundation of China(62304181)the Natural Science Basic Research Program of Shaanxi(2023-JC-QN-0726,2025JC-YBQN-469)the GuangdongBasic and Applied Basic Research Foundation(2022A1515110286,2024A1515012538)the Basic Research Programs of Taicang(TC2024JC04)the Suzhou Science and Technology Development Plan Innovation Leading Talent Project(ZXL2023183)the Fundamental Research Funds for the Central Universities(G2022KY05108,G2024KY0605,G2023KY0601)and the Aeronautical Science Foundation of China(2018ZD53047).
文摘Achieving simultaneous enhancement of crystallinity and optimal domain size remains a fundamental challenge in organic photovoltaics(OPVs),where conventional crystallization strategies often trigger excessive aggregation of small-molecule acceptors.This work pioneers a kinetic paradigm for resolving the crystallinity-domain size trade-off in organic photovoltaics through dual-additive-guided stepwise crystallization.By strategically pairing 1,2-dichlorobenzene(o-DCB,low binding energy to Y6)and 1-fluoronaphthalene(FN,high binding energy),we achieve temporally decoupled crystallization control:o-DCB first mediates donor-acceptor co-crystallization during film formation,constructing a metastable network,whereupon FN induces confined Y6 crystallization within this framework during thermal annealing,refining nanostructure without over-aggregation.Morphology studies reveal that this synergy enhances crystallinity of(100)diffraction peaks by 21%–10%versus single-additive controls(o-DCB/FN alone),while maintaining optimal domain size.These morphological advantages yield balanced carrier transport(μh/μe=1.23),near-unity exciton dissociation(98.53%),and a champion power conversion efficiency(PCE)of 18.08%for PM6:Y6,significantly surpassing single-additive devices(o-DCB:17.20%;FN:17.53%).Crucially,the dual-additive strategy demonstrates universal applicability across diverse active layer systems,achieving an outstanding PCE of 19.27%in PM6:L8-BO-based devices,thereby establishing a general framework for morphology control in high-efficiency OPVs.
基金financially supported and funded by the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University(IMSIU)(No.IMSIU-DDRSP2503)。
文摘Functionally graded cellular structures(FGCSs)have a multitude of applications to a wide range of industries.Utilising the ever-progressing technology of additive manufacturing(AM),FGCSs can be applied to control material grading and achieve the desired mechanical properties.The current study explores the design and optimisation of FGCSs for AM,with a focus on improving the compression and impact performance of below knee(BK)prosthetic limbs made of thermoplastic polyurethane(TPU).A multiscale research methodology integrating topology optimization(TO),finite element analysis(FEA),and design of experiments(Do E)was adopted to optimise lattice structures in terms of stiffness and lightweight properties.Two-unit cell designs were considered in the study:Schwarz P gyroid and body-centered cubic(BCC).Response surface methodology(RSM)was implemented to analyse the effect of minimum and maximum cell wall thickness,cell size,and unit cell type on the mechanical performance of TPU FGCS structures.The results indicated that a Schwarz P FGCS structure with cell size,minimum and maximum cell wall thickness of 6,0.9 and 2.8 mm,respectively,could be optimal for a compromise between performance and weight.In this optimized case,stiffness and volume fraction values of 684 N/mm and 0.64 were obtained,respectively.The study also presents a proof-of-concept design for a BK prosthetic damper,highlighting the potential of FGCSs to enhance patient comfort,reduce manufacturing costs,and enable personalised designs through 3D scanning and AM.The obtained results could be a step forward towards the incorporation of AM technologies in prosthetics,offering a pathway to lightweight,cost-effective,and functionally tailored solutions.
基金support of the National Natural Science Foundation of China(Grant/Project Nos.52272027,52372034 and 52502016)the China Postdoctoral Science Foundation(Grant No.2025T180025)Postdoctoral Fellowship Program(Grant No.GZC20252393).
文摘The accelerated shift toward high efficiency and sustainability of the iron and steel is driving the advancement of green,low-carbon and high-quality carbon-containing refractories used for ladles.It is undoubtedly a significant challenge,since the addition of graphite enables refractories to possess superior thermal shock resistance and slag corrosion resistance.To develop low carbon-containing refractories with excellent properties,researchers over the past decades have endeavored to seek additives which can mitigate the adverse effects associated with the decrease in carbon in refractories.These additives can promote the occurrence of various mechanisms about toughening,which depends on inherent properties of additives or reacting with refractories to in situ form different ceramic phases,thereby responding the challenge of low-carbonization in refractories.The latest advances in additives used for low carbon-containing refractories from metal/alloys,oxide,non-oxide and composite powders four aspects were comprehensively overviewed in this review.Oxide additives exhibit a moderate effect on improving thermal shock resistance of refractories but show limited efficacy in improving oxidation resistance.In contrast,non-oxide additives demonstrate remarkable advantages in enhancing both oxidation and slag corrosion resistance.Composite powders combine the advantageous properties of their individual components.These additives often require combination with antioxidants such as Al,Si,or B4C not only to reduce costs but also to achieve optimal properties.Furthermore,future perspectives of these additives are discussed,with the aim of providing useful insights for the continuous progress and practical application of low carbon-containing refractories.
基金support of the National Natural Science Foundation of China(No.52574411)Beijing Natural Science Foundation(No.2242043).
文摘Achieving high energy and power densities is currently a core challenge in the fabrication of energy storage materials.Although numerous high-capacity materials have been developed,conventional planar electrodes cannot achieve high active material loading and efficient ion/electron transport simultaneously.By contrast,three-dimensional(3D)structures have attracted increasing interest because of their capacity to enhance active material utilization,shorten ion and electron transport pathways,reduce interfacial impedance,and provide spatial accommodation for volume expansion.Additive manufacturing(AM)technology effectively fabricates energy-storage materials with 3D structures by accurately constructing complex 3D structures via layer-by-layer deposition.Recent studies have employed AM to construct ordered 3D electrodes that can optimize ion/electron transport,regulate electric field distribution,or improve the electrode-electrolyte interface,thereby contributing to enhanced kinetic performance and cycling stability.This review systematically summarizes the applications of several AM technologies in the fabrication of energy storage materials and analyzes their respective advantages and limitations.Subsequently,the advantages of AM technology in the fabrication of energy storage materials and several major optimization strategies are comprehensively discussed.Finally,the major challenges and potential applications of AM technology in energy storage material optimization are discussed.
基金supported by the Khalifa University of Science and Technology internal grants(Nos.2021-CIRA-109,2020-CIRA-007,and 2020-CIRA-024).
文摘Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-inspired lattice structures feature a square-grid 2D lattice with double diagonal bracings and are additively manufactured via digital light processing(DLP).The collapse strength and energy absorption capacity of sea sponge lattice structures are evaluated under various impact conditions and are compared to those of their constituent square-grid and double diagonal lattices.This study demonstrates that sea sponge lattices can achieve an 11-fold increase in energy absorption compared to the square-grid lattice,due to the stabilizing effect of the double diagonal bracings prompting the structure to collapse layer-bylayer under impact.By adjusting the thickness ratio in the sea sponge lattice,up to 76.7%increment in energy absorption is attained.It is also shown that sea-sponge lattices outperform well-established energy-absorbing materials of equal weight,such as hexagonal honeycombs,confirming their significant potential for impact mitigation.Additionally,this research highlights the enhancements in energy absorption achieved by adding a small amount(0.015 phr)of Multi-Walled Carbon Nanotubes(MWCNTs)to the photocurable resin,thus unlocking new possibilities for the design of innovative lightweight structures with multifunctional attributes.
文摘The effects of nitrogen(N)deposition on forest soil organic carbon(SOC)are largely unclear,likely due to the divergent responses of particulate(POC)and mineral-associated carbon(MAOC).Conventional understory inorganic N(UIN)additions neglect canopy processes and the impacts of organic N,potentially misevaluating N deposition effects.This study was conducted in a long-term N addition experiment established in a Moso bamboo forest,which included six treatments combining canopy and understory N additions with organic(urea glycine)and inorganic(NH_(4)NO_(3))forms at a rate of 50 kg N·ha^(-1)·yr^(-1).Litterbags were installed for a two-year decomposition experiment and collected at quarterly intervals,together with concurrent soil sampling under litterbags at 0–10 cm depth.We aimed to examine the effects of canopy vs.understory N addition and organic vs.inorganic N form on soil POC and MAOC concentrations.Our results showed that canopy N additions significantly reduced POC(ased POC-15.9%)but did not affect MAOC(P>0.05).Conversely,understory N additions significantly incre(30.9%)and decreased MAOC(and fungal diversity(FuD),-28.9%).Canopy N additions decreased POC by enhancing peroxidase activity while understory N additions promoted POC by inhibiting litter decomposition.Additionally,understory N addition-induced soil acidification decreased soil Ca^(2+)concentration,microbial carbon use efficiency,and bacterial necromass C,as well as the release of litter water-soluble compounds,thereby inhibiting MAOC.Moreover,nitrogen forms(organic vs.inorganic)had no effect on SOC fractions.Our findings underscore that canopy and understory N addition approaches differentially regulate SOC fractions by altering litter decomposition–microbial–mineral interactions,and the understory approach may overestimate soil POC gain and MAOC loss driven by atmospheric N deposition.
文摘Human epidermal growth factor receptor 2(HER2)-overexpressing breast cancer is an aggressive phenotype with a poor prognosis,and can easily metastasize and recur.Currently,chemotherapy plus HER2-targeted therapy is the standard systemic treatment for most of these patients.Given that neoadjuvant chemotherapy(NAC)has an efficacy equivalent to that of adjuvant chemotherapy and some additional benefits,many patients,especially those with more advanced tumors,prefer NAC and generally will not receive additional chemotherapy after surgery,irrespective of the pathological response.However,achieving pathological complete response to NAC is strongly correlated with prognosis,especially in triple-negative and HER2-overexpressing breast cancer.Therefore,postoperative treatment of these patients with residual diseases should be optimized to achieve favorable outcomes.The CREATE-X study has confirmed that additional chemotherapy can improve the outcomes of patients with HER2-negative residual disease after NAC.In addition,chemotherapy plays an indispensable role in the treatment of patients who receive surgery directly or who have recurrent lesions.Therefore,can additional chemotherapy improve prognosis of patients with HER2-overexpressing residual breast cancer?At present,no studies have compared the efficacy of additional chemotherapy plus trastuzumab with that of anti-HER2 therapy alone in residual cancer.The KATHERINE study revealed that trastuzumab emtansine(T-DM1)can reduce the risk of recurrence or death by 50%compared with trastuzumab in patients with HER2-positive residual invasive breast cancer after neoadjuvant therapy.T-DM1 is an antibody-drug conjugate of trastuzumab and the cytotoxic agent emtansine,and thus,to an extent,T-DM1 is equivalent to simultaneous application of chemotherapy and targeted therapy.However,high cost and low accessibility limit its use especially in low-and middle-income countries and regions.Hence,we proposed this perspective that additional chemotherapy plus trastuzumab should be given to HER2-overexpressing breast cancer patients with residual disease after NAC to improve their prognosis by discussing that the efficacy of additional chemotherapy plus trastuzumab is superior to that of anti-HER2 therapy alone and not inferior to T-DM1.Additional chemotherapy plus trastuzumab-based HER2-targeted therapy can be used as an alternative regimen to T-DM1 when T-DM1 is unavailable.However,further clinical research on the selection of chemotherapeutic agents is warranted.
文摘The model of skaft lining under force is developed on the basis of the special stratum condition led to sbart cracking- The model is broken into 3 sub-questions to solve separately. According to the principle of superposition and strain compatibility, a second kind Fredholm integral equation is generated.A theoretical solution to vertical additional force on shaft lining is obtained by numerical method to the integral equation.
基金supported by National Natural Science Foundation of China(Grant No.51105001)State Key Laboratory of Automotive Safety and Energy,Tsinghua University,China(Grant No.KF14022)
文摘The current research of real-time observation for vehicle roll steer angle and compliance steer angle（both of them comprehensively referred as the additional steer angle in this paper） mainly employs the linear vehicle dynamic model, in which only the lateral acceleration of vehicle body is considered. The observation accuracy resorting to this method cannot meet the requirements of vehicle real-time stability control, especially under extreme driving conditions. The paper explores the solution resorting to experimental method. Firstly, a multi-body dynamic model of a passenger car is built based on the ADAMS/Car software, whose dynamic accuracy is verified by the same vehicle＇s roadway test data of steady static circular test. Based on this simulation platform, several influencing factors of additional steer angle under different driving conditions are quantitatively analyzed. Then ε-SVR algorithm is employed to build the additional steer angle prediction model, whose input vectors mainly include the sensor information of standard electronic stability control system（ESC）. The method of typical slalom tests and FMVSS 126 tests are adopted to make simulation, train model and test model＇s generalization performance. The test result shows that the influence of lateral acceleration on additional steer angle is maximal （the magnitude up to 1°）, followed by the longitudinal acceleration-deceleration and the road wave amplitude （the magnitude up to 0.3°）. Moreover, both the prediction accuracy and the calculation real-time of the model can meet the control requirements of ESC This research expands the accurate observation methods of the additional steer angle under extreme driving conditions.
文摘An alluvium with a sandy aquifer at the bottom,but lacking an effective impermeable layer between the sandy aquifer and bedrock is referred to as a special alluvial stratum.Impacted by the drainage of the aquifer due to mining activities,a shaft wall in this special alluvial stratum will be subject to a downward load by an additional vertical force which must be taken into consideration in the design of the shaft wall.The complexity of interaction between shaft wall and the surrounding walls makes it extremely difficult to determine this additional vertical force.For a particular shaft wall in an extra-thick alluvium and assuming that the friction coefficient between shaft wall and stratum does not change with depth,an analysis of a numerical simulation of the stress within the shaft wall has been carried out.Growth and size of the additional vertical stress have been obtained,based on specific values of the friction coefficient,the modulus of elasticity of the drainage layer and the thickness of the drainage layer.Subsequently, the safety of shaft walls with different structural types was studied and a more suitable structural design,providing an important basis for the design of shaft walls,is promoted.
