Fe-based amorphous and nanocrystalline coatings were fabricated by air plasma spraying. The coatings were further treated by laser remelting process to improve their microstructure and properties. The corrosion resist...Fe-based amorphous and nanocrystalline coatings were fabricated by air plasma spraying. The coatings were further treated by laser remelting process to improve their microstructure and properties. The corrosion resistance of the as-sprayed and laser-remelted coatings in 3.5wt% NaC1 and 1 mol/L HCI solutions was evaluated by electrochemical polarization analysis. It was found that laser-remelted coating appeared much denser than the as-sprayed coating. However, laser-remelted coating contains much more nanocrystalline grains than the as-sprayed coatings, resulting from the lower cooling rate in laser remelting process compared with plasma spraying process. Electrochemical polarization results indicated that the laser-remelted coating has great corrosion resistance than the as-sprayed coating because of its dense structure.展开更多
The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the h...The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous- nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.展开更多
A hydraulic power unit （HPU） is the driving ＂heart＂ of deep-sea working equipment. It is critical to predict its dynamic performances in deep-water before being immerged in the seawater, while the experimental tes...A hydraulic power unit （HPU） is the driving ＂heart＂ of deep-sea working equipment. It is critical to predict its dynamic performances in deep-water before being immerged in the seawater, while the experimental tests by simulating deep-sea environment have many disadvantages, such as expensive cost, long test cycles, and difficult to achieve low-temperature simulation, which is only used as a supplementary means for confirmatory experiment. This paper proposes a novel theoretical approach based on the linear varying parameters （LVP） modeling to foresee the dynamic performances of the driving unit. Firstly, based on the varying environment features, dynamic expressions of the compressibility and viscosity of hydranlic oil are derived to reveal the fluid performances changing. Secondly, models of hydraulic system and electrical system are accomplished respectively through studying the control process and energy transfer, and then LVP models of the pressure and flow rate control is obtained through the electro-hydraulic models integration. Thirdly, dynamic characteristics of HPU are obtained by the model simulating within bounded closed sets of varying parameters. Finally, the developed HPU is tested in a deep-sea imitating hull, and the experimental results are well consistent with the theoretical analysis outcomes, which clearly declare that the LVP modeling is a rational way to foresee dynamic performances of HPU. The research approach and model analysis results can be applied to the predictions of working properties and product designs for other deep-sea hydraulic pump.展开更多
In this study,we propose an efficient numerical framework to attain the solution of the extended Fisher-Kolmogorov(EFK)problem.The temporal derivative in the EFK equation is approximated by utilizing the Crank-Nicolso...In this study,we propose an efficient numerical framework to attain the solution of the extended Fisher-Kolmogorov(EFK)problem.The temporal derivative in the EFK equation is approximated by utilizing the Crank-Nicolson scheme.Following temporal discretization,the generalized finite difference method(GFDM)with supplementary nodes is utilized to address the nonlinear boundary value problems at each time node.These supplementary nodes are distributed along the boundary to match the number of boundary nodes.By incorporating supplementary nodes,the resulting nonlinear algebraic equations can effectively satisfy the governing equation and boundary conditions of the EFK equation.To demonstrate the efficacy of our approach,we present three numerical examples showcasing its performance in solving this nonlinear problem.展开更多
Accurate aging diagnosis is crucial for the health and safety management of lithium-ion batteries in electric vehicles.Despite significant advancements achieved by data-driven methods,diagnosis accuracy remains constr...Accurate aging diagnosis is crucial for the health and safety management of lithium-ion batteries in electric vehicles.Despite significant advancements achieved by data-driven methods,diagnosis accuracy remains constrained by the high costs of check-up tests and the scarcity of labeled data.This paper presents a framework utilizing self-supervised machine learning to harness the potential of unlabeled data for diagnosing battery aging in electric vehicles during field operations.We validate our method using battery degradation datasets collected over more than two years from twenty real-world electric vehicles.Our analysis comprehensively addresses cell inconsistencies,physical interpretations,and charging uncertainties in real-world applications.This is achieved through self-supervised feature extraction using random short charging sequences in the main peak of incremental capacity curves.By leveraging inexpensive unlabeled data in a self-supervised approach,our method demonstrates improvements in average root mean square errors of 74.54%and 60.50%in the best and worst cases,respectively,compared to the supervised benchmark.This work underscores the potential of employing low-cost unlabeled data with self-supervised machine learning for effective battery health and safety management in realworld scenarios.展开更多
Ionic polymer-metal composites(IPMCs)constitute a new type of artificial muscle material that is commonly used in bionic soft robots and medical devices because of its small driving voltage and considerable deformatio...Ionic polymer-metal composites(IPMCs)constitute a new type of artificial muscle material that is commonly used in bionic soft robots and medical devices because of its small driving voltage and considerable deformation.However,IPMCs are limited by performance issues such as low output force and small operating time away from water.Silicon dioxide sulfonated graphene(SiO_(2)-SGO)particles are often used to improve the performance of polymer membranes because of their hydrophilicity and high chemical stability.Reported here is the addition of SiO_(2)-SGO particles prepared by in situ hydrolysis to perfluorosulfonic acid in order to improve the IPMC properties.Also,a predictive model was constructed based on a backpropagation neural network,with the SiO_(2)-SGO doping amount and the IPMC excitation voltage in the input layer and the driving displacement in the output layer.The results show that the IPMC prepared with 1.0 wt.%doping content performed the best,with a maximum output displacement of 47.7 mm.The correlation coefficient(R2)was 0.9842 and the mean square error was 0.00037073,which show that the predictive model has high predictive accuracy and is suitable for predicting the performance of the SiO_(2)-SGO-modified IPMC.展开更多
In order to verify the effectiveness and superiority of the dynamic hybrid RANS/LES(DHRL)model,the flow around a cylinder with sinusoidal fluctuating velocity at the inlet was used as the test case.The latest computat...In order to verify the effectiveness and superiority of the dynamic hybrid RANS/LES(DHRL)model,the flow around a cylinder with sinusoidal fluctuating velocity at the inlet was used as the test case.The latest computational fluid dynamics(CFD)model can flexibly choose any existing large-eddy simulation(LES)method combined with RANS method to calculate the flow field.In addition,the DLES model and DDES model are selected as typical representatives of the turbulence model to compare the capture ability of the flow field mechanism.The internal flow field including the y+value,velocity distribution,turbulent kinetic energy and vortex structures is comprehensively analyzed.Finally,the results show that the new model has enough sensitivity to capture the information of the flow field and has more consistent velocity distribution with the experimental value,which shows its potential in practical engineering applications to some extent.展开更多
The parameters for the electro-deposition of Cu were optimized in order to increase the compressive properties of close cell aluminum. Different values of deposition voltages and times were considered to vary the amou...The parameters for the electro-deposition of Cu were optimized in order to increase the compressive properties of close cell aluminum. Different values of deposition voltages and times were considered to vary the amount of deposited Cu. The surface morphology of the coating was observed by SEM and the compressive properties were evaluated by MTS. The results show that the coating is more homogeneous and compact with increasing voltage in a certain range, and beyond which, the coating quality decreases apparently. The reason is dedicated to the discharge rate of Cu2+ and nucleus formed in unit time. The compression results show three experienced stages: elastic deformation stage, collapse deformation stage and densification stage. After the electro-deposition of Cu, the elasticity modulus is increased obviously and the platform stress is also increased. Under the same strain, the stress of the aluminum foam with coating is reinforced comparing with the aluminum foam without coating. Furthermore, the platform area is widened apparently. In addition, Cu-SiC nanocomposite coatings are electrodeposited in alumium foams for further improving the mechanical characterization.展开更多
This study presents a simple technique for strengthening the adhesive-bond strength between aluminium(Al)substrate and carbon fibre reinforced polymer(CFRP) utilising resin pre-coating(RPC) with carbon nanotubes(CNTs)...This study presents a simple technique for strengthening the adhesive-bond strength between aluminium(Al)substrate and carbon fibre reinforced polymer(CFRP) utilising resin pre-coating(RPC) with carbon nanotubes(CNTs). The CNT-containing RPC solution with 90 wt% acetone and 10 wt% resin(without hardener) was applied onto Al substrates, where micro-/nano-vertical channels had been created by chemical or mechanical surface treatments to accommodate CNTs. RPC was able to fill all micro-/nano-cavities over the Al substrate surface, then CNTs were pulled into those vertical micro-channels by the capillary action generated from acetone evaporation.Normal epoxy adhesive(resin + hardener) was applied after the CNT-containing RPC treatment. CNTs bridging across the interface between the adhesive joint and Al substrate and sealing of micro-/nano-cavities by RPC effectively enhanced the interfacial shear bond strength between the Al substrate and CFRP by 30–100%depending on the Al substrate surface profiles. Al substrates with two different chemical treatments were compared in this study for the effectiveness of CNT interfacial reinforcement. Results from a steel substrate after sandblasting were also included for comparison.展开更多
The spheroidization behavior of the dendritic b.c.c, phase dispersed in a bulk metallic glass （BMG） matrix was investigated through applying semi-solid isothermal processing and a subsequent rapid quenching procedur...The spheroidization behavior of the dendritic b.c.c, phase dispersed in a bulk metallic glass （BMG） matrix was investigated through applying semi-solid isothermal processing and a subsequent rapid quenching procedure to a Zr-basedβ-phase composite. The Zr-based composite with the composition of Z%62Ti138NbsoCuegNi5.6Be125 was prefabricated by a water-cooled copper mold-casting method and characterized by X-ray diffraction （XRD） and scanning electron microscope （SEM）. The results show that the composite consists of a glassy matrix and uniformly distributed fine dendrites of theβ-Zr solid solution with the body-centered-cubic （b.c.c.） structure. Based on the differential scanning calorimeter （DSC） examination results, and in view of the b.c.c.β-Zr to h.c.p, α-Zr phase transition temperature, a semi-solid holding temperature of 900 ℃ was determined. After reheating the prefabricated composite to the semi-solid temperature, followed by an isothermal holding process at this temperature for 5 min, and then quenching the semi-solid mixture into iced-water; the two-phase microstructure composed of a BMG matrix and uniformly dispersed spherical b.c.c.β-Zr particles with a high degree of sphericity was achieved. The present spheroidization transition is a thermodynamically autonomic behavior, and essentially a diffusion process controlled by kinetic factors; and the formation of the BMG matrix should be attributed to the rapid quenching of the semi-solid mixture as well as the large glass-forming ability of the remaining melt in the semi-solid mixture.展开更多
In order to study the mechanical properties and the dynamic performance of torque converter,to reduce the vibration and noise during the operation and to improve the stability,a 215 mm hydraulic torque converter is ta...In order to study the mechanical properties and the dynamic performance of torque converter,to reduce the vibration and noise during the operation and to improve the stability,a 215 mm hydraulic torque converter is taken as the research object,and modal analyses are performed based on the finite element method.The weak parts of the impeller structure are obtained after calculating the models of the impeller and turbine without prestress.The variation of the modal frequency of the turbine and impeller are obtained under different prestress conditions by calculating different rotational speeds of the transmission shaft.The fundamental frequencies of the impeller and the turbine increase by 0.43%and 4.82%respectively when the rotational speed ranges from 100 rpm to 4500 rpm.The results of the present research indicate that the modal frequencies at different speeds are similar to the fundamental frequencies of the structure.Therefore,it is possible to estimate the vibration characteristics of the structure and optimize the structural design by numerical modal analysis in the static state instead of the dynamic state.展开更多
Achieving dynamic compliance for energy-efficient legged robot motion is a longstanding challenge.Although recent predictive control methods based on single-rigid-body models can generate dynamic motion,they all assum...Achieving dynamic compliance for energy-efficient legged robot motion is a longstanding challenge.Although recent predictive control methods based on single-rigid-body models can generate dynamic motion,they all assume infinite energy,making them unsuitable for prolonged robot operation.Addressing this issue necessitates a mechanical structure with energy storage and a dynamic control strategy that incorporates feedback to ensure stability.This work draws inspiration from the efficiency of bio-inspired muscle–tendon networks and proposes a controllable torsion spring leg structure.The design integrates a spring-loaded inverted pendulum model and adopts feedback delays and yield springs to enhance the delay effects.A leg control model that incorporates motor loads is developed to validate the response and dynamic performance of a leg with elastic joints.This model provides torque to the knee joint,effectively reducing the robot’s energy consumption through active or passive control strategies.The benefits of the proposed approach in agile maneuvering of quadruped robot legs in a realistic scenario are demonstrated to validate the dynamic motion performance of the leg with elastic joints with the advantage of energy-efficient legs.展开更多
This work used high velocity oxygen fuel spraying technology to prepare three types of ceramic-based self-lubricating sealing coating on C/SiC substrates,with Yttria-stabilized zirconia as the matrix and different mas...This work used high velocity oxygen fuel spraying technology to prepare three types of ceramic-based self-lubricating sealing coating on C/SiC substrates,with Yttria-stabilized zirconia as the matrix and different mass fractions of Mo and Ag as lubricating phases.The compositions are S1(50%YSZ40%CaF_(2)10%Mo),S2(50%YSZ40%CaF_(2)10%Ag)and S3(40%YSZ30%CaF_(2)10%Mo10%Ag10%SiO_(2)).The friction coefficient and wear rate of the coating were examined at room temperature(RT),400℃and 800℃.The effects of different lubricating phases on the tribological properties of the coating were compared.The wear mechanism of the coating under different temperature environments will be revealed by clarifying the evolution law of the microstructure of the coating.The results show that the addition of Ag can improve the lubricating ability of the coating.Ag element forms a continuous and smooth tribo-layer on the sliding surface to reduce the friction coefficient of the coating.In addition,the lubricating effect of Ag element is more significant at medium and low temperatures.At 800℃,the S3 coating with both Ag and Mo exhibited excellent tribological properties.The wear mechanism of the coating is that it starts with adhesive wear and gradually transitions to abrasive wear as friction continues.This work provides theoretical support and experimental evidence for the construction of ceramic-based self-lubricating sealing coating with a wide temperature range.展开更多
This paper proposes a new approach to mial function of transmission error （TE） for spiral design and implement a seventh-order polyno- bevel gears with an aim to reduce the running vibration and noise of gear drive ...This paper proposes a new approach to mial function of transmission error （TE） for spiral design and implement a seventh-order polyno- bevel gears with an aim to reduce the running vibration and noise of gear drive and improve the loaded distribution of the tooth. Based on the constraint conditions of predesigned seventh-order polynomial function curve and the theory of linear algebra, the polynomial coefficients of the seventh-order polynomial function of transmission error can be obtained. By applying a method named reverse tooth contact analysis, the modified roll coefficients as well as parts of machine-tool settings for the face-milling of spiral bevel gears can be individually determined. Therefore, a predesigned seventh-order polynomial function of transmission error for spiral bevel gears can be obtained by the modified roll with high-order coef- ficients, and comparisons of the seventh-order polynomial and parabolic functions of transmission error are also performed. The achievement of spiral bevel gears with the seventh-order function of transmission error can be accomplished on a universal Cartesian-type hypoid gear generator or a numerically controlled cradle-style hypoid gear generator due to its simple generating motion of axes of the cradle and the work piece. The results of a numerical example show that the bending stresses of the tooth of seventh-order are less than those of a parabolic one, while the contact stresses remain almost eouivalent.展开更多
Fe-based and Fe/Mo composite amorphous coatings were deposited on the surface of plain carbon steel substrates by atmospheric plasma spraying （APS）. With increasing the Mo alloy content, the microstructure of the co...Fe-based and Fe/Mo composite amorphous coatings were deposited on the surface of plain carbon steel substrates by atmospheric plasma spraying （APS）. With increasing the Mo alloy content, the microstructure of the coatings revealed more dense structure. The porosities of composite coating were all less than those of Fe-based coat- ing due to Mo alloy self-bonding performance. The ML10 friction and wear tester was employed to investigate the wear behaviors of the coatings under dry sliding conditions. It was found that the mass loss of the resultant coatings decreased with increasing Mo-based powders into the feedstock. This was attributed to the reduction of the delamina- tions resulting from improved intersplat bond with Mo addition.展开更多
In this study,we prepare the specimens of three-dimensional random fibrous(3D RF)material along its through-the-thickness(TTT)and in-plane(IP)directions.The experimental tests of tensile and compressive properties as ...In this study,we prepare the specimens of three-dimensional random fibrous(3D RF)material along its through-the-thickness(TTT)and in-plane(IP)directions.The experimental tests of tensile and compressive properties as well as fracture toughness of 3D RF material are performed at elevated temperatures.Then,the porosity(83%,87%and 89%)and temperature dependence of the tensile and compressive strength,elastic modulus,fracture toughness and fracture surface energy of the 3D RF materials for both the TTT and IP directions are analyzed.From the results of the tensile strength and elastic modulus versus material porosities at various temperatures,we find that tensile strength and elastic modulus for the TTT direction are more sensitive to the porosity,but not for the IP direction.Fracture toughness increases firstly and then decreases at a certain critical temperature.Such critical temperature is found to be the lowest for the porosity of 83%.On the other hand,at below 1073 K,the temperature-dependent fracture surface energies with three porosities for the TTT direction show similar variation trends.展开更多
Although the torso plays an important role in the movement coordination and versatile locomotion of mammals,the structural design and neuromechanical control of a bionic torso have not been fully addressed.In this pap...Although the torso plays an important role in the movement coordination and versatile locomotion of mammals,the structural design and neuromechanical control of a bionic torso have not been fully addressed.In this paper,a parallel mechanism is designed as a bionic torso to improve the agility,coordination,and diversity of robot locomotion.The mechanism consists of 6-degree of freedom actuated parallel joints and can perfectly simulate the bending and stretching of an animal’s torso during walking and running.The overall spatial motion performance of the parallel mechanism is improved by optimizing the structural parameters.Based on this structure,the rhythmic motion of the parallel mechanism is obtained by supporting state analysis.The neural control of the parallel mechanism is realized by constructing a neuromechanical network,which merges the rhythmic signals of the legs and generates the locomotion of the bionic parallel mechanism for different motion patterns.Experimental results show that the complete integrated system can be controlled in real time to achieve proper limb-torso coordination.This coordination enables several different motions with effectiveness and good performance.展开更多
This article introduces the application of image recognition technology in cement pavement crack detection and put forward to method fordetermining threshold about grayscale stretching. This algorithm is designed for ...This article introduces the application of image recognition technology in cement pavement crack detection and put forward to method fordetermining threshold about grayscale stretching. This algorithm is designed for binarization which has a self-adaptive characteristic. After theimage is preprocessed, we apply 2D wavelet and Laplace operator to process the image. According to the characteristic of pixel of gray image, analgorithm designed on binarization for Binary image. The feasibility of this method can be verified the image processed by comparing with theresults of three algorithms: Otsu method, iteration method and fixed threshold method.展开更多
Based on the biological characteristics of tulip,the low driving voltage and fast response of ionic polymer metal composite(IPMC),we analyzed the fabrication,morphology and performance of the platinum IPMC(Pt-IPMC)and...Based on the biological characteristics of tulip,the low driving voltage and fast response of ionic polymer metal composite(IPMC),we analyzed the fabrication,morphology and performance of the platinum IPMC(Pt-IPMC)and selected the right IPMC for driving bionic tulip.The preparation and performance of IPMC was analyzed first in this paper such as blocking force,output displacement and bending angle of IPMC under the different directed current voltage(DC).The optimal IPMC sample size and driving voltage were selected based on tulip blooming angles and the strain energy density of IPMC,which completed the blooming process of bionic tulip.The feasibility of IPMC used in driving bionic field was fully proved in this paper,which laid a foundation for the application of IPMC in driving biomimetic biological robots.展开更多
In recent years,more and more creatures in nature have become the source of inspiration for people to study bionic soft robots.Many such robots appear in the public’s vision.In this paper,a Venus flytrap robot simila...In recent years,more and more creatures in nature have become the source of inspiration for people to study bionic soft robots.Many such robots appear in the public’s vision.In this paper,a Venus flytrap robot similar to the biological Venus flytrap in appearance was designed and prepared.It was mainly cast by Polydimethylsiloxane(PDMs)and driven by the flexible material of Ionic Polymer Metal Composites(IPMCs).Combining with ANSYS and related experiments,the appropriate voltage and the size of IPMC were determined.The results showed that the performance of the Venus flytrap robot was the closest to the biological Venus flytrap when the size of IPMC length,width and driving voltage reach to 3 cm,1 cm and 5.5 V,respectively.Moreover,the closing speed and angle reached 8.22°/s and 37°,respectively.Finally,the fly traps also could be opened and closed repeatedly and captured a small ball with a mass of 0.3 g firmly in its middle and tip.展开更多
基金Funded by the Special Found for Basic Scientific Research of Central Colleges,Chang'an University(2014G1311093)the AQSIQ Technology Program Project(2013QK111)
文摘Fe-based amorphous and nanocrystalline coatings were fabricated by air plasma spraying. The coatings were further treated by laser remelting process to improve their microstructure and properties. The corrosion resistance of the as-sprayed and laser-remelted coatings in 3.5wt% NaC1 and 1 mol/L HCI solutions was evaluated by electrochemical polarization analysis. It was found that laser-remelted coating appeared much denser than the as-sprayed coating. However, laser-remelted coating contains much more nanocrystalline grains than the as-sprayed coatings, resulting from the lower cooling rate in laser remelting process compared with plasma spraying process. Electrochemical polarization results indicated that the laser-remelted coating has great corrosion resistance than the as-sprayed coating because of its dense structure.
基金Funded by the Basic Scientific Research of Central Colleges,Chang’an University (No. CHD2011JC126)
文摘The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous- nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.
基金supported by the National High Technology Research and Development Program of China (863 Program,Grant Nos. 2006AA09Z226 and 2012AA091104)the Special Fund for Basic Scientific Research of Central Colleges,Chang’an University (Grant No. CHD2011JC151)
文摘A hydraulic power unit （HPU） is the driving ＂heart＂ of deep-sea working equipment. It is critical to predict its dynamic performances in deep-water before being immerged in the seawater, while the experimental tests by simulating deep-sea environment have many disadvantages, such as expensive cost, long test cycles, and difficult to achieve low-temperature simulation, which is only used as a supplementary means for confirmatory experiment. This paper proposes a novel theoretical approach based on the linear varying parameters （LVP） modeling to foresee the dynamic performances of the driving unit. Firstly, based on the varying environment features, dynamic expressions of the compressibility and viscosity of hydranlic oil are derived to reveal the fluid performances changing. Secondly, models of hydraulic system and electrical system are accomplished respectively through studying the control process and energy transfer, and then LVP models of the pressure and flow rate control is obtained through the electro-hydraulic models integration. Thirdly, dynamic characteristics of HPU are obtained by the model simulating within bounded closed sets of varying parameters. Finally, the developed HPU is tested in a deep-sea imitating hull, and the experimental results are well consistent with the theoretical analysis outcomes, which clearly declare that the LVP modeling is a rational way to foresee dynamic performances of HPU. The research approach and model analysis results can be applied to the predictions of working properties and product designs for other deep-sea hydraulic pump.
基金supported by the Key Laboratory of Road Construction Technology and Equipment(Chang’an University,No.300102253502)the Natural Science Foundation of Shandong Province of China(GrantNo.ZR2022YQ06)the Development Plan of Youth Innovation Team in Colleges and Universities of Shandong Province(Grant No.2022KJ140).
文摘In this study,we propose an efficient numerical framework to attain the solution of the extended Fisher-Kolmogorov(EFK)problem.The temporal derivative in the EFK equation is approximated by utilizing the Crank-Nicolson scheme.Following temporal discretization,the generalized finite difference method(GFDM)with supplementary nodes is utilized to address the nonlinear boundary value problems at each time node.These supplementary nodes are distributed along the boundary to match the number of boundary nodes.By incorporating supplementary nodes,the resulting nonlinear algebraic equations can effectively satisfy the governing equation and boundary conditions of the EFK equation.To demonstrate the efficacy of our approach,we present three numerical examples showcasing its performance in solving this nonlinear problem.
基金supported by the research project‘‘SafeDaBatt”(03EMF0409A)funded by the German Federal Ministry for Digital and Transport(BMDV)+2 种基金the National Key Research and Development Program of China(2022YFE0102700)the Key Research and Development Program of Shaanxi Province(2023-GHYB-05,2023-YBSF-104)the financial support from the China Scholarship Council(CSC)(202206567008)。
文摘Accurate aging diagnosis is crucial for the health and safety management of lithium-ion batteries in electric vehicles.Despite significant advancements achieved by data-driven methods,diagnosis accuracy remains constrained by the high costs of check-up tests and the scarcity of labeled data.This paper presents a framework utilizing self-supervised machine learning to harness the potential of unlabeled data for diagnosing battery aging in electric vehicles during field operations.We validate our method using battery degradation datasets collected over more than two years from twenty real-world electric vehicles.Our analysis comprehensively addresses cell inconsistencies,physical interpretations,and charging uncertainties in real-world applications.This is achieved through self-supervised feature extraction using random short charging sequences in the main peak of incremental capacity curves.By leveraging inexpensive unlabeled data in a self-supervised approach,our method demonstrates improvements in average root mean square errors of 74.54%and 60.50%in the best and worst cases,respectively,compared to the supervised benchmark.This work underscores the potential of employing low-cost unlabeled data with self-supervised machine learning for effective battery health and safety management in realworld scenarios.
基金funded by the Digital workshop dynamic Reconstruction modeling Technology(Grant No.2020YFB1710701)the National Natural Science Foundation of China(Grant No.52172099)the Provincial Joint Fund of Shaanxi(Grant No.2021JLM-28).
文摘Ionic polymer-metal composites(IPMCs)constitute a new type of artificial muscle material that is commonly used in bionic soft robots and medical devices because of its small driving voltage and considerable deformation.However,IPMCs are limited by performance issues such as low output force and small operating time away from water.Silicon dioxide sulfonated graphene(SiO_(2)-SGO)particles are often used to improve the performance of polymer membranes because of their hydrophilicity and high chemical stability.Reported here is the addition of SiO_(2)-SGO particles prepared by in situ hydrolysis to perfluorosulfonic acid in order to improve the IPMC properties.Also,a predictive model was constructed based on a backpropagation neural network,with the SiO_(2)-SGO doping amount and the IPMC excitation voltage in the input layer and the driving displacement in the output layer.The results show that the IPMC prepared with 1.0 wt.%doping content performed the best,with a maximum output displacement of 47.7 mm.The correlation coefficient(R2)was 0.9842 and the mean square error was 0.00037073,which show that the predictive model has high predictive accuracy and is suitable for predicting the performance of the SiO_(2)-SGO-modified IPMC.
基金Supported by the Open Fund of Key Laboratory of Road Construction Technology and Equipment of Chang’an University,Ministry of Education(310825171104)the Advanced Manufacturing Projects of Government and University Co-construction Program Funded by Jilin Province(SXGJSF2017-2)
文摘In order to verify the effectiveness and superiority of the dynamic hybrid RANS/LES(DHRL)model,the flow around a cylinder with sinusoidal fluctuating velocity at the inlet was used as the test case.The latest computational fluid dynamics(CFD)model can flexibly choose any existing large-eddy simulation(LES)method combined with RANS method to calculate the flow field.In addition,the DLES model and DDES model are selected as typical representatives of the turbulence model to compare the capture ability of the flow field mechanism.The internal flow field including the y+value,velocity distribution,turbulent kinetic energy and vortex structures is comprehensively analyzed.Finally,the results show that the new model has enough sensitivity to capture the information of the flow field and has more consistent velocity distribution with the experimental value,which shows its potential in practical engineering applications to some extent.
基金Funded in Part by the Fundamental Research Funds for the Central Universities(Nos.300102318205,310831161020,310831163401)the National Natural Science Foundation of China(No.51301021)+2 种基金the China Postdoctoral Science Foundation(No.2016M592730)the Innovation and Entrepreneurship Training Program of Chang’an University(No.201610710084)the Fund of the State Key Laboratory of Solidification and Processing in Northwestern Polytechnical University(No.SKLSP201302)
文摘The parameters for the electro-deposition of Cu were optimized in order to increase the compressive properties of close cell aluminum. Different values of deposition voltages and times were considered to vary the amount of deposited Cu. The surface morphology of the coating was observed by SEM and the compressive properties were evaluated by MTS. The results show that the coating is more homogeneous and compact with increasing voltage in a certain range, and beyond which, the coating quality decreases apparently. The reason is dedicated to the discharge rate of Cu2+ and nucleus formed in unit time. The compression results show three experienced stages: elastic deformation stage, collapse deformation stage and densification stage. After the electro-deposition of Cu, the elasticity modulus is increased obviously and the platform stress is also increased. Under the same strain, the stress of the aluminum foam with coating is reinforced comparing with the aluminum foam without coating. Furthermore, the platform area is widened apparently. In addition, Cu-SiC nanocomposite coatings are electrodeposited in alumium foams for further improving the mechanical characterization.
基金Chang’an University of China for a visiting professor grant (2018-2020) for research collaboration between Chang’an University and University of Western Australia。
文摘This study presents a simple technique for strengthening the adhesive-bond strength between aluminium(Al)substrate and carbon fibre reinforced polymer(CFRP) utilising resin pre-coating(RPC) with carbon nanotubes(CNTs). The CNT-containing RPC solution with 90 wt% acetone and 10 wt% resin(without hardener) was applied onto Al substrates, where micro-/nano-vertical channels had been created by chemical or mechanical surface treatments to accommodate CNTs. RPC was able to fill all micro-/nano-cavities over the Al substrate surface, then CNTs were pulled into those vertical micro-channels by the capillary action generated from acetone evaporation.Normal epoxy adhesive(resin + hardener) was applied after the CNT-containing RPC treatment. CNTs bridging across the interface between the adhesive joint and Al substrate and sealing of micro-/nano-cavities by RPC effectively enhanced the interfacial shear bond strength between the Al substrate and CFRP by 30–100%depending on the Al substrate surface profiles. Al substrates with two different chemical treatments were compared in this study for the effectiveness of CNT interfacial reinforcement. Results from a steel substrate after sandblasting were also included for comparison.
基金supported by the Natural Science Research Projects of The Education Department of Henan Province,China(Grant No.2008A430010)the R&D start-up projects of high-level talents of North China University of Water Resources and Electric Power(Grant No.200709)
文摘The spheroidization behavior of the dendritic b.c.c, phase dispersed in a bulk metallic glass （BMG） matrix was investigated through applying semi-solid isothermal processing and a subsequent rapid quenching procedure to a Zr-basedβ-phase composite. The Zr-based composite with the composition of Z%62Ti138NbsoCuegNi5.6Be125 was prefabricated by a water-cooled copper mold-casting method and characterized by X-ray diffraction （XRD） and scanning electron microscope （SEM）. The results show that the composite consists of a glassy matrix and uniformly distributed fine dendrites of theβ-Zr solid solution with the body-centered-cubic （b.c.c.） structure. Based on the differential scanning calorimeter （DSC） examination results, and in view of the b.c.c.β-Zr to h.c.p, α-Zr phase transition temperature, a semi-solid holding temperature of 900 ℃ was determined. After reheating the prefabricated composite to the semi-solid temperature, followed by an isothermal holding process at this temperature for 5 min, and then quenching the semi-solid mixture into iced-water; the two-phase microstructure composed of a BMG matrix and uniformly dispersed spherical b.c.c.β-Zr particles with a high degree of sphericity was achieved. The present spheroidization transition is a thermodynamically autonomic behavior, and essentially a diffusion process controlled by kinetic factors; and the formation of the BMG matrix should be attributed to the rapid quenching of the semi-solid mixture as well as the large glass-forming ability of the remaining melt in the semi-solid mixture.
基金Supported by the China Postdoctoral Science Foundation(No.2019M663913XB)Shaanxi Key Laboratory of Mine Electromechanical Equipment Intelligent Monitoring(Xi’an University of Science and Technology)(No.SKL-MEEIM201907)+2 种基金Natural Science Basic Research Plan in Shaanxi Province of China(No.2019JZ-10)Science and Technology Program of Tibet Autonomous Region(No.XZ2019TL-G-02)Fundamental Research Funds for the Central Universities(No.300102250106)。
文摘In order to study the mechanical properties and the dynamic performance of torque converter,to reduce the vibration and noise during the operation and to improve the stability,a 215 mm hydraulic torque converter is taken as the research object,and modal analyses are performed based on the finite element method.The weak parts of the impeller structure are obtained after calculating the models of the impeller and turbine without prestress.The variation of the modal frequency of the turbine and impeller are obtained under different prestress conditions by calculating different rotational speeds of the transmission shaft.The fundamental frequencies of the impeller and the turbine increase by 0.43%and 4.82%respectively when the rotational speed ranges from 100 rpm to 4500 rpm.The results of the present research indicate that the modal frequencies at different speeds are similar to the fundamental frequencies of the structure.Therefore,it is possible to estimate the vibration characteristics of the structure and optimize the structural design by numerical modal analysis in the static state instead of the dynamic state.
基金supported in part by the National Natural Science Foundation of China(Grant No.62373064)in part by the State Key Laboratory of Robotics and Systems,Harbin Institute of Technology,China(Grant No.SKLRS-2023-KF-05)in part by the Fundamental Research Funds for Central Universities,China(Grants Nos.300102259308,300102259401).
文摘Achieving dynamic compliance for energy-efficient legged robot motion is a longstanding challenge.Although recent predictive control methods based on single-rigid-body models can generate dynamic motion,they all assume infinite energy,making them unsuitable for prolonged robot operation.Addressing this issue necessitates a mechanical structure with energy storage and a dynamic control strategy that incorporates feedback to ensure stability.This work draws inspiration from the efficiency of bio-inspired muscle–tendon networks and proposes a controllable torsion spring leg structure.The design integrates a spring-loaded inverted pendulum model and adopts feedback delays and yield springs to enhance the delay effects.A leg control model that incorporates motor loads is developed to validate the response and dynamic performance of a leg with elastic joints.This model provides torque to the knee joint,effectively reducing the robot’s energy consumption through active or passive control strategies.The benefits of the proposed approach in agile maneuvering of quadruped robot legs in a realistic scenario are demonstrated to validate the dynamic motion performance of the leg with elastic joints with the advantage of energy-efficient legs.
基金supported by the National Natural Science Foundation of China(No.52105211)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(Grant No.2023-TS-04)the Research Fund of Pre-research Projects(No.0730-2411080386).
文摘This work used high velocity oxygen fuel spraying technology to prepare three types of ceramic-based self-lubricating sealing coating on C/SiC substrates,with Yttria-stabilized zirconia as the matrix and different mass fractions of Mo and Ag as lubricating phases.The compositions are S1(50%YSZ40%CaF_(2)10%Mo),S2(50%YSZ40%CaF_(2)10%Ag)and S3(40%YSZ30%CaF_(2)10%Mo10%Ag10%SiO_(2)).The friction coefficient and wear rate of the coating were examined at room temperature(RT),400℃and 800℃.The effects of different lubricating phases on the tribological properties of the coating were compared.The wear mechanism of the coating under different temperature environments will be revealed by clarifying the evolution law of the microstructure of the coating.The results show that the addition of Ag can improve the lubricating ability of the coating.Ag element forms a continuous and smooth tribo-layer on the sliding surface to reduce the friction coefficient of the coating.In addition,the lubricating effect of Ag element is more significant at medium and low temperatures.At 800℃,the S3 coating with both Ag and Mo exhibited excellent tribological properties.The wear mechanism of the coating is that it starts with adhesive wear and gradually transitions to abrasive wear as friction continues.This work provides theoretical support and experimental evidence for the construction of ceramic-based self-lubricating sealing coating with a wide temperature range.
基金the National Science Foundation of China (Nos.51205310 and 51175423)the Fundamental Research Funds for the Central Universities (Nos.2013G3252005 and 2013G2252027)
文摘This paper proposes a new approach to mial function of transmission error （TE） for spiral design and implement a seventh-order polyno- bevel gears with an aim to reduce the running vibration and noise of gear drive and improve the loaded distribution of the tooth. Based on the constraint conditions of predesigned seventh-order polynomial function curve and the theory of linear algebra, the polynomial coefficients of the seventh-order polynomial function of transmission error can be obtained. By applying a method named reverse tooth contact analysis, the modified roll coefficients as well as parts of machine-tool settings for the face-milling of spiral bevel gears can be individually determined. Therefore, a predesigned seventh-order polynomial function of transmission error for spiral bevel gears can be obtained by the modified roll with high-order coef- ficients, and comparisons of the seventh-order polynomial and parabolic functions of transmission error are also performed. The achievement of spiral bevel gears with the seventh-order function of transmission error can be accomplished on a universal Cartesian-type hypoid gear generator or a numerically controlled cradle-style hypoid gear generator due to its simple generating motion of axes of the cradle and the work piece. The results of a numerical example show that the bending stresses of the tooth of seventh-order are less than those of a parabolic one, while the contact stresses remain almost eouivalent.
基金the Special Found for Basic Scientific Research of Central Colleges,Chang'an University (00092014G1311093)the Special Fund for Basic Research Support Plan of Chang'an Universitythe Open Fund of Engineering Research Center of Transportation Materials,Ministry of Education of China
文摘Fe-based and Fe/Mo composite amorphous coatings were deposited on the surface of plain carbon steel substrates by atmospheric plasma spraying （APS）. With increasing the Mo alloy content, the microstructure of the coatings revealed more dense structure. The porosities of composite coating were all less than those of Fe-based coat- ing due to Mo alloy self-bonding performance. The ML10 friction and wear tester was employed to investigate the wear behaviors of the coatings under dry sliding conditions. It was found that the mass loss of the resultant coatings decreased with increasing Mo-based powders into the feedstock. This was attributed to the reduction of the delamina- tions resulting from improved intersplat bond with Mo addition.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.11902046,11632014,11372238 and 11872049)the Chang Jiang Scholar Program and the 111 Project(Grant No.B18040)This work was also supported by the Fundam ental Research Funds for the Central Universities,CHD(Grant No.300102259302).
文摘In this study,we prepare the specimens of three-dimensional random fibrous(3D RF)material along its through-the-thickness(TTT)and in-plane(IP)directions.The experimental tests of tensile and compressive properties as well as fracture toughness of 3D RF material are performed at elevated temperatures.Then,the porosity(83%,87%and 89%)and temperature dependence of the tensile and compressive strength,elastic modulus,fracture toughness and fracture surface energy of the 3D RF materials for both the TTT and IP directions are analyzed.From the results of the tensile strength and elastic modulus versus material porosities at various temperatures,we find that tensile strength and elastic modulus for the TTT direction are more sensitive to the porosity,but not for the IP direction.Fracture toughness increases firstly and then decreases at a certain critical temperature.Such critical temperature is found to be the lowest for the porosity of 83%.On the other hand,at below 1073 K,the temperature-dependent fracture surface energies with three porosities for the TTT direction show similar variation trends.
基金This work was supported in part by the National Natural Science Foundation of China(Grant No.51605039)in part by the Shaanxi International Science and Technology Cooperation Project(Grant No.2020KW-064)+3 种基金in part by the Open Foundation of the State Key Laboratory of Fluid Power Transmission and Control(Grant No.GZKF-201923)in part by the China Postdoctoral Science Foundation(Grant No.2018T111005)in part by the Fundamental Research Funds for the Central Universities(Grant Nos.300102259308 and 300102259401)in part by the China Scholarship Council.
文摘Although the torso plays an important role in the movement coordination and versatile locomotion of mammals,the structural design and neuromechanical control of a bionic torso have not been fully addressed.In this paper,a parallel mechanism is designed as a bionic torso to improve the agility,coordination,and diversity of robot locomotion.The mechanism consists of 6-degree of freedom actuated parallel joints and can perfectly simulate the bending and stretching of an animal’s torso during walking and running.The overall spatial motion performance of the parallel mechanism is improved by optimizing the structural parameters.Based on this structure,the rhythmic motion of the parallel mechanism is obtained by supporting state analysis.The neural control of the parallel mechanism is realized by constructing a neuromechanical network,which merges the rhythmic signals of the legs and generates the locomotion of the bionic parallel mechanism for different motion patterns.Experimental results show that the complete integrated system can be controlled in real time to achieve proper limb-torso coordination.This coordination enables several different motions with effectiveness and good performance.
文摘This article introduces the application of image recognition technology in cement pavement crack detection and put forward to method fordetermining threshold about grayscale stretching. This algorithm is designed for binarization which has a self-adaptive characteristic. After theimage is preprocessed, we apply 2D wavelet and Laplace operator to process the image. According to the characteristic of pixel of gray image, analgorithm designed on binarization for Binary image. The feasibility of this method can be verified the image processed by comparing with theresults of three algorithms: Otsu method, iteration method and fixed threshold method.
基金The authors acknowledge the financial assistance from the Key Laboratory Project of Expressway Construction Machinery of Shaanxi Province,China(300102259510)the Key Research and Development Program of Shaanxi Province,China(2018ZDXM-GY-088).
文摘Based on the biological characteristics of tulip,the low driving voltage and fast response of ionic polymer metal composite(IPMC),we analyzed the fabrication,morphology and performance of the platinum IPMC(Pt-IPMC)and selected the right IPMC for driving bionic tulip.The preparation and performance of IPMC was analyzed first in this paper such as blocking force,output displacement and bending angle of IPMC under the different directed current voltage(DC).The optimal IPMC sample size and driving voltage were selected based on tulip blooming angles and the strain energy density of IPMC,which completed the blooming process of bionic tulip.The feasibility of IPMC used in driving bionic field was fully proved in this paper,which laid a foundation for the application of IPMC in driving biomimetic biological robots.
基金financial assistance from the Key Laboratory Project of Expressway Construction Machinery of Shaanxi Province,China(300102259510)the Key Research and Development Program of Shaanxi Province,China(2018ZDXM-GY-088)+1 种基金Analysis and compensation friction error of inclined installation feed system for NC machine tools,China(17JK0509)Study on mechanism and suppression strategy of friction error for CNC machine tools,China(2017JM5042).
文摘In recent years,more and more creatures in nature have become the source of inspiration for people to study bionic soft robots.Many such robots appear in the public’s vision.In this paper,a Venus flytrap robot similar to the biological Venus flytrap in appearance was designed and prepared.It was mainly cast by Polydimethylsiloxane(PDMs)and driven by the flexible material of Ionic Polymer Metal Composites(IPMCs).Combining with ANSYS and related experiments,the appropriate voltage and the size of IPMC were determined.The results showed that the performance of the Venus flytrap robot was the closest to the biological Venus flytrap when the size of IPMC length,width and driving voltage reach to 3 cm,1 cm and 5.5 V,respectively.Moreover,the closing speed and angle reached 8.22°/s and 37°,respectively.Finally,the fly traps also could be opened and closed repeatedly and captured a small ball with a mass of 0.3 g firmly in its middle and tip.
