Blank holder force(BHF)is a crucial parameter in deep drawing,having close relation with the forming quality of sheet metal.However,there are different BHFs maintaining the best forming effect in different stages of d...Blank holder force(BHF)is a crucial parameter in deep drawing,having close relation with the forming quality of sheet metal.However,there are different BHFs maintaining the best forming effect in different stages of deep drawing.The variable blank holder force(VBHF)varying with the drawing stage can overcome this problem at an extent.The optimization of VBHF is to determine the optimal BHF in every deep drawing stage.In this paper,a new heuristic optimization algorithm named Jaya is introduced to solve the optimization efficiently.An improved“Quasi-oppositional”strategy is added to Jaya algorithm for improving population diversity.Meanwhile,an innovated stop criterion is added for better convergence.Firstly,the quality evaluation criteria for wrinkling and tearing are built.Secondly,the Kriging models are developed to approximate and quantify the relation between VBHF and forming defects under random sampling.Finally,the optimization models are established and solved by the improved QO-Jaya algorithm.A VBHF optimization example of component with complicated shape and thin wall is studied to prove the effectiveness of the improved Jaya algorithm.The optimization results are compared with that obtained by other algorithms based on the TOPSIS method.展开更多
While the rechargeable aqueous zinc-ion batteries(AZIBs)have been recognized as one of the most viable batteries for scale-up application,the instability on Zn anode–electrolyte interface bottleneck the further devel...While the rechargeable aqueous zinc-ion batteries(AZIBs)have been recognized as one of the most viable batteries for scale-up application,the instability on Zn anode–electrolyte interface bottleneck the further development dramatically.Herein,we utilize the amino acid glycine(Gly)as an electrolyte additive to stabilize the Zn anode–electrolyte interface.The unique interfacial chemistry is facilitated by the synergistic“anchor-capture”effect of polar groups in Gly molecule,manifested by simultaneously coupling the amino to anchor on the surface of Zn anode and the carboxyl to capture Zn^(2+)in the local region.As such,this robust anode–electrolyte interface inhibits the disordered migration of Zn^(2+),and effectively suppresses both side reactions and dendrite growth.The reversibility of Zn anode achieves a significant improvement with an average Coulombic efficiency of 99.22%at 1 mA cm^(−2)and 0.5 mAh cm^(−2)over 500 cycles.Even at a high Zn utilization rate(depth of discharge,DODZn)of 68%,a steady cycle life up to 200 h is obtained for ultrathin Zn foils(20μm).The superior rate capability and long-term cycle stability of Zn–MnO_(2)full cells further prove the effectiveness of Gly in stabilizing Zn anode.This work sheds light on additive designing from the specific roles of polar groups for AZIBs.展开更多
Microfluidic device with patterned microstructures on the substrate surface was used to regulate cell adhesion,morphology,and functions in tissue engineering.We developed a microfluidic device which employing microsca...Microfluidic device with patterned microstructures on the substrate surface was used to regulate cell adhesion,morphology,and functions in tissue engineering.We developed a microfluidic device which employing microscale patterned microstructures to achieve enhanced cell adhesion and migration.Biocompatible hydrogel substrates with micro-wavy and lattice-patterned microstructures were fabricated using standing surface acoustic waves and ultraviolet solidification.After seeding the L929 mouse fibroblast cells onto the patterned substrate of the microfluidic device,we determined that the viability and proliferation rate of cell migration can be greatly enhanced.Furthermore,L929 cells showed two types of gathering modes after 48 h of culturing.Cell growth was guided by the patterned substrate used in the microfluidic device and showed differences in the location distribution.Therefore,the developed microfluidic device with patterned microstructures can extend the application of in vitro cell culturing for future drug development and disease diagnosis.展开更多
The negative pressure conical fluidized bed is widely used in the pharmaceutical industry.In this study,experiments based on the negative pressure conical fluidized bed are carried out by changing the material mass an...The negative pressure conical fluidized bed is widely used in the pharmaceutical industry.In this study,experiments based on the negative pressure conical fluidized bed are carried out by changing the material mass and particle size.The pressure fluctuation signals are analyzed by the time and the frequency domain methods.A method for absolutely characterizing the degree of the energy concentration at the main frequency is proposed,where the calculation is to divide the original power spectrum by the average signal power.A phenomenon where the gas velocity curve temporarily stops growing is observed when the material mass is light,and the particle size is small.The standard deviation and kurtosis both rapidly change at the minimum fluidization velocity and thus can be used to determine the flow regime,and the variation rule of the kurtosis is independent of both the material mass and particle size.In the initial fluidization stage,the dominant pressure signal comes from the material movement;with the increase in the gas velocity,the power of a 2.5 Hz signal continues to increase.A method of dividing the main frequency by the average cycle frequency can conveniently determine the fluidized state,and a novel concept called stable fluidized zone proposed in this paper can be obtained.Controlling the gas velocity within the stable fluidized zone ensures that the fluidized bed consistently remains in a stable fluidized state.展开更多
The trend towards automation and intelligence in aircraft final assembly testing has led to a new demand for autonomous perception of unknown cockpit operation scenes in robotic collaborative airborne system testing.T...The trend towards automation and intelligence in aircraft final assembly testing has led to a new demand for autonomous perception of unknown cockpit operation scenes in robotic collaborative airborne system testing.To address this demand,a robotic automated 3D reconstruction cell which enables to autonomously plan the robot end-camera’s trajectory is developed for image acquisition and 3D modeling of the cockpit operation scene.A continuous viewpoint path planning algorithm is proposed that incorporates both 3D reconstruction quality and robot path quality into optimization process.Smoothness metrics for viewpoint position paths and orientation paths are introduced together for the first time in 3D reconstruction.To ensure safe and effective movement,two spatial constraints,Domain of View Admissible Position(DVAP)and Domain of View Admissible Orientation(DVAO),are implemented to account for robot reachability and collision avoidance.By using diffeomorphism mapping,the orientation path is transformed into 3D,consistent with the position path.Both orientation and position paths can be optimized in a unified framework to maximize the gain of reconstruction quality and path smoothness within DVAP and DVAO.The reconstruction cell is capable of automatic data acquisition and fine scene modeling,using the generated robot C-space trajectory.Simulation and physical scene experiments have confirmed the effectiveness of the proposed method to achieve highprecision 3D reconstruction while optimizing robot motion quality.展开更多
The pulsed-spray fluid-bed granulation (PSFBG) process was investigated and optimized using definitive scree ning design, a recently proposed new class of three-level desig n of experiment method. Such a design enable...The pulsed-spray fluid-bed granulation (PSFBG) process was investigated and optimized using definitive scree ning design, a recently proposed new class of three-level desig n of experiment method. Such a design enabled quadratic models to be established that described the effect of six in put process parameters - inlet air temperature, inlet air humidity, binder spray rate, atomization pressure, pulse period, and pulse width - on the granule quality in a PSFBG process. Mathematical models of the mean particle size, relative size distribution width, production yield, and porosity were developed to quantify the relationships between the in flue ncing factors and critical quality attributes. On the basis of con strai nts on the desired granule properties, a design space for PSFBG was determined and ranges of the operating parameters were defined. An acceptable degree of prediction was confirmed by validation experiments, demonstrating the reliability and effectiveness of using definitive screening design to study the PSFBG process. This method can accelerate screening and optimization of this process within a large multidimensional design space.展开更多
Ultra-thin sheets of titanium for fabricating microchannels have been used in fuel cells due to their good corrosion resistance and high strength-weight ratio. This paper presents a constitutive model for studying the...Ultra-thin sheets of titanium for fabricating microchannels have been used in fuel cells due to their good corrosion resistance and high strength-weight ratio. This paper presents a constitutive model for studying the anisotropy effects of pure titanium(CP-Ti) sheet on the springback behavior and forming properties during the microstamping process. Thin sheets of CP-Ti specimens with different orientations were examined using uniaxial tensile tests to assess the effects of anisotropy on their mechanical properties. Then an anisotropic constitutive model considering the off-axis elastic modulus was developed based on orthotropic elasticity and Hill's yield criterion. Numerical modeling and simulation of the microstamping process for fabricating multi-channel structures were performed. The effects of anisotropy on the springback of multi-channels were investigated and compared with experimental results;the effects of tool dimension parameters on the formability of microchannel structures were also analyzed. The results showed that the anisotropy of thin titanium sheets causes various degrees of forming loads and springback in the microstamping of microchannels at different orientations. This study accurately predicts the springback of thin titanium sheet used to fabricate microchannel structures and is a good guide to the formation of such structures.展开更多
Automated Fiber Placement(AFP)technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However.the unavoidable imperfections induced by t...Automated Fiber Placement(AFP)technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However.the unavoidable imperfections induced by the automated layup method bring challenges to the stability of the final mechanical properties of composites.The influence of AFP-induced gaps and overlaps on the modeⅡinterlaminar fracture process of oven-cured laminates is experimentally investigated and explicitly revealed.End-Notched Flexure(ENF)tests were performed to measure the interlaminar fracture toughness of unidirectional laminates under three different defect configurations,namely"Gap""Overlap"and"Gap&Overlap".A marginal decline(about-1.2%in non-precracked tests,-5.1%in precracked tests)and an obvious increase(about 15.2%in nonprecracked tests,5.2%in precracked tests)in fracture toughness were observed for the"Gap"group and the"Overlap"group,respectively.Fractographic studies which involve the metallographic observation and Scanning Electron Microscopy(SEM)observation revealed that the increases in fracture area and crack length helped improve the fracture toughness of the Overlap"group.However,the resin-rich area with high porosity induced by gaps was detrimental to the delamination resistance.To capture the interlaminar stress distribution local to imperfections,a three-dimensional numerical model was established.Gap defects facilitate the local delamination process,and the overlap defect postpones the damage onset and the propagation.展开更多
Selective laser melting(SLM)is a unique additive manufacturing(AM)category that can be used to manufacture mechanical parts.It has been widely used in aerospace and automotive using metal or alloy powder.The build ori...Selective laser melting(SLM)is a unique additive manufacturing(AM)category that can be used to manufacture mechanical parts.It has been widely used in aerospace and automotive using metal or alloy powder.The build orientation is crucial in AM because it affects the as-built part,including its part accuracy,surface roughness,support structure,and build time and cost.A mechanical part is usually composed of multiple surface features.The surface features carry the production and design knowledge,which can be utilized in SLM fabrication.This study proposes a method to determine the build orientation of multi-feature mechanical parts(MFMPs)in SLM.First,the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives.Second,the estimation models of involved optimization objectives are established,and a set of alternative build orientations(ABOs)is further obtained by many-objective optimization.Lastly,a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs.The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process.Two case studies are reported to validate the proposed method with numerical results,and the effectiveness comparison is presented.Physical manufacturing is conducted to prove the performance of the proposed method.The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82,10.84,and 10.62μm,respectively.The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.展开更多
Surface accuracy directly affects the surface quality and performance of mechanical parts.Circular hole,especially spatial non-planar hole set is the typical feature and working surface of mechanical parts.Compared wi...Surface accuracy directly affects the surface quality and performance of mechanical parts.Circular hole,especially spatial non-planar hole set is the typical feature and working surface of mechanical parts.Compared with traditional machining methods,additive manufacturing(AM)technology can decrease the surface accuracy errors of circular holes during fabrication.However,an accuracy error may still exist on the surface of circular holes fabricated by AM due to the influence of staircase effect.This study proposes a surface accuracy optimization approach for mechanical parts with multiple circular holes for AM based on triangular fuzzy number(TFN).First,the feature lines on the manifold mesh are extracted using the dihedral angle method and normal tensor voting to detect the circular holes.Second,the optimal AM part build orientation is determined using the genetic algorithm to optimize the surface accuracy of the circular holes by minimizing the weighted volumetric error of the part.Third,the corresponding weights of the circular holes are calculated with the TFN analytic hierarchy process in accordance with the surface accuracy requirements.Lastly,an improved adaptive slicing algorithm is utilized to reduce the entire build time while maintaining the forming surface accuracy of the circular holes using digital twins via virtual printing.The effectiveness of the proposed approach is experimentally validated using two mechanical models.展开更多
For efficient use of value stream mapping(VSM)for multi-varieties and small batch production in a data-rich environment enabled by Industry 4.0 technologies,a systematic framework of VSM to rejuvenate traditional lean...For efficient use of value stream mapping(VSM)for multi-varieties and small batch production in a data-rich environment enabled by Industry 4.0 technologies,a systematic framework of VSM to rejuvenate traditional lean tools is proposed.It addresses the issue that traditional VSM requires intensive on-site investigation and replies on experience,which hinders decisionmaking efficiency in dynamic and complex environments.The proposed framework follows the data-information-knowledge hierarchy model,and demonstrates how data can be collected in a production workshop,processed into information,and then interpreted into knowledge.In this paper,the necessity and limitations of VSM in automated root cause analysis are first discussed,with a literature review on lean production tools,especially VSM and VSM-based decision making in Industry 4.0.An implementation case of a furniture manufacturer in China is presented,where decision tree algorithm was used for automated root cause analysis.The results indicate that automated VSM can make good use of production data to cater for multi-varieties and small batch production with timely on-site waste identification and analysis.The proposed framework is also suggested as a guideline to renew other lean tools for reliable and efficient decision-making.展开更多
Large-scale cryogenic air separation units(ASUs),which are widely used in global petrochemical and semiconductor industries,are being developed with high operating elasticity under variable working conditions.Differen...Large-scale cryogenic air separation units(ASUs),which are widely used in global petrochemical and semiconductor industries,are being developed with high operating elasticity under variable working conditions.Different from discrete processes in traditional machinery manufacturing,the ASU process is continuous and involves the compression,adsorption,cooling,condensation,liquefaction,evaporation,and distillation of multiple streams.This feature indicates that thousands of technical parameters in adsorption,heat transfer,and distillation processes are correlated and merged into a large-scale complex system.A lumped parameter model(LPM)of ASU is proposed by lumping the main factors together and simplifying the secondary ones to achieve accurate and fast performance design.On the basis of material and energy conservation laws,the piecewise-lumped parameters are extracted under variable working conditions by using LPM.Takagi–Sugeno(T–S)fuzzy interval detection is recursively utilized to determine whether the critical point is detected or not by using different thresholds.Compared with the traditional method,LPM is particularly suitable for“rough first then precise”modeling by expanding the feasible domain using fuzzy intervals.With LPM,the performance of the air compressor,molecular sieve adsorber,turbo expander,main plate-fin heat exchangers,and packing column of a 100000 Nm3 O2/h large-scale ASU is enhanced to adapt to variable working conditions.The designed value of net power consumption per unit of oxygen production(kW/(Nm3 O2))is reduced by 6.45%.展开更多
Pulsed spray is a useful tool forgranule size control in fluid bed granulation.To improve the quality control of pulsed-spray fluid bed granulation,a combination of in-line near-infrared(NIR)spectroscopy and p「incipa...Pulsed spray is a useful tool forgranule size control in fluid bed granulation.To improve the quality control of pulsed-spray fluid bed granulation,a combination of in-line near-infrared(NIR)spectroscopy and p「incipal component analysis was used to develop multivariate statistical process control(MSPC)charts.Different types of MSPC charts were developed,including principal component score charts,Hotelling's T2 control charts,and distance to model X control charts,to monitor the batch evolution throughout the granulation process.Correlation optimized warping was used as an alignment method to deal with the time variation in batches caused by the granulation mechanism in MSPC modeling.The control charts developed in this study were validated on normal batches and tested on four batches that deviated from normal processing conditions to achieve real-time fault analysis.The results indicated that the NIR spectroscopy-based MSPC model included the variability in the sample set constituting the model and could withstand external variability.This research demonstrated the application of synchronized NIR spectra in conjunction w让h multivariate batch modeling as an attractive tool for process monitoring and a fault diagnosis method for effective process control in pulsed-spray fluid bed granulation.展开更多
Polymer-based materials with patterned functional particles have been used to develop smart devices with multiple functionalities.This paper presents a novel method to pattern microscale particles into biocompatible p...Polymer-based materials with patterned functional particles have been used to develop smart devices with multiple functionalities.This paper presents a novel method to pattern microscale particles into biocompatible polyethylene glycol diacrylate(PEGDA)fluid through a designed surface acoustic wave(SAW)device with slanted-finger interdigital transducers(SFITs).By applying signals of different frequencies,the SFITs can excite SAWs with various wavelengths to pattern the microscale particles.The structural design and working principle of the SAW device with SFITs are firstly presented.To investigate the generation of standing SAWs and pressure field distributions of the SAW device with SFITs,a numerical model was developed.Simulation results showed that different strip-shape patterned pressure fields can be generated,and the period and width of adjacent strips can be adjusted by changing the frequencies of the excitation signals.Experiments were performed to verify that the microscale particles in the PEGDA solution can be successfully patterned into strip-shape patterns with various positions,periods,and widths.The results obtained in this study demonstrate that the developed method of using an SAW device with SFITs can be used for tunable patterning of microscale particles in solutions,and shows great potential for biomedical and microfluidic applications.展开更多
Tactile sensors have been used for haptic perception in intelligent robotics,smart prosthetics,and human-machine interface.The development of multifunctional tactile sensor remains a challenge and limit its applicatio...Tactile sensors have been used for haptic perception in intelligent robotics,smart prosthetics,and human-machine interface.The development of multifunctional tactile sensor remains a challenge and limit its application in flexible electronics and devices.We propose a liquid metal based tactile sensor for both temperature and force sensing which is made by 3D printing.The structural design and working principle of liquid metal based tactile sensor are firstly described.A digital light processing-based printing process is developed to print two kinds of photosensitive resins with different hardness,and used to fabricate the tactile sensor.A Wheatstone bridge circuit is designed for decoupling the temperature and forces from the measured output voltages.Characterization tests show that the tactile sensor has relatively high force sensing sensitivity of 0.29 N^(-1),and temperature sensing sensitivities are 0.55%°C−1 at 20~50°C and 0.21%°C^(−1)at 50~80°C,respectively.Then,the fabricated tactile sensor is mounted onto hand finger to measure the contact force and temperature during grasping.Results show that the 3D printed tactile sensor has excellent flexibility and durability and can accurately measure the temperature and contact forces,which demonstrate its potential in robotic manipulation applications.展开更多
Vectored non-covalent interactions—mainly hydrogen bonding and aromatic interactions—extensively contribute to(bio)-organic self-assembling processes and significantly impact the physicochemical properties of the as...Vectored non-covalent interactions—mainly hydrogen bonding and aromatic interactions—extensively contribute to(bio)-organic self-assembling processes and significantly impact the physicochemical properties of the associated superstructures.However,vectored non-covalent interaction-driven assembly occursmainly along one-dimensional(1D)or three-dimensional(3D)directions,and a two-dimensional(2D)orientation,especially that of multilayered,graphene-like assembly,has been reported less.In this present research,by introducing amino,hydroxyl,and phenyl moieties to the triazine skeleton,supramolecular layered assembly is achieved by vectored non-covalent interactions.The planar hydrogen bonding network results in high stability,with a thermal sustainability of up to about 330°C and a Young’s modulus of up to about 40 GPa.Upon introducing wrinkles by biased hydrogen bonding or aromatic interactions to disturb the planar organization,the stability attenuates.However,the intertwined aromatic interactions prompt a red edge excitation shift effect inside the assemblies,inducing broad-spectrum fluorescence covering nearly the entire visible light region(400–650 nm).We show that bionic,superhydrophobic,pillar-like arrays with contact angles of up to about 170°can be engineered by aromatic interactions using a physical vapor deposition approach,which cannot be realized through hydrogen bonding.Our findings show the feasibility of 2D assembly with engineerable properties by modulating vectored non-covalent interactions.展开更多
Photonic crystals(PCs)exhibit promising structural coloration properties and possess extensive application prospects in diverse optical fields.However,state-of-the-art inorganic or polymeric PCs show limited adaptivit...Photonic crystals(PCs)exhibit promising structural coloration properties and possess extensive application prospects in diverse optical fields.However,state-of-the-art inorganic or polymeric PCs show limited adaptivity as their configurations are fixed once formed.Herein,bio-organic adaptive PCs are fabricated via drop-casting of amphiphilic guanine-based peptide nucleic acid selfassembled microspheres.The high formation activation energy of up to 81.8 kJ·mol−1 suggests that the self-assembly step dominates the entire process.Therefore,the configurations along with the structural coloration of the supramolecular PCs are sensitive to self-assembly influencing parameters,showing temperature-encoded structural color evolution and solvent polaritydependent solvatochromism.Our findings demonstrate that the supramolecular PCs are adaptive,thus showing promising potential for detection of organic solvents of different polarities in a visual and real-time manner for environmental protection or optical applications.展开更多
基金Supported by National Key Research and Development Program of China(Grant No.2022YFB3304200)National Natural Science Foundation of China(Grant No.52075479)Taizhou Municipal Science and Technology Project of China(Grant No.1801gy23).
文摘Blank holder force(BHF)is a crucial parameter in deep drawing,having close relation with the forming quality of sheet metal.However,there are different BHFs maintaining the best forming effect in different stages of deep drawing.The variable blank holder force(VBHF)varying with the drawing stage can overcome this problem at an extent.The optimization of VBHF is to determine the optimal BHF in every deep drawing stage.In this paper,a new heuristic optimization algorithm named Jaya is introduced to solve the optimization efficiently.An improved“Quasi-oppositional”strategy is added to Jaya algorithm for improving population diversity.Meanwhile,an innovated stop criterion is added for better convergence.Firstly,the quality evaluation criteria for wrinkling and tearing are built.Secondly,the Kriging models are developed to approximate and quantify the relation between VBHF and forming defects under random sampling.Finally,the optimization models are established and solved by the improved QO-Jaya algorithm.A VBHF optimization example of component with complicated shape and thin wall is studied to prove the effectiveness of the improved Jaya algorithm.The optimization results are compared with that obtained by other algorithms based on the TOPSIS method.
基金supported by National Key R&D Program(2022YFB2502000)Zhejiang Provincial Natural Science Foundation of China(LZ23B030003)+1 种基金the Fundamental Research Funds for the Central Universities(2021FZZX001-09)the National Natural Science Foundation of China(52175551).
文摘While the rechargeable aqueous zinc-ion batteries(AZIBs)have been recognized as one of the most viable batteries for scale-up application,the instability on Zn anode–electrolyte interface bottleneck the further development dramatically.Herein,we utilize the amino acid glycine(Gly)as an electrolyte additive to stabilize the Zn anode–electrolyte interface.The unique interfacial chemistry is facilitated by the synergistic“anchor-capture”effect of polar groups in Gly molecule,manifested by simultaneously coupling the amino to anchor on the surface of Zn anode and the carboxyl to capture Zn^(2+)in the local region.As such,this robust anode–electrolyte interface inhibits the disordered migration of Zn^(2+),and effectively suppresses both side reactions and dendrite growth.The reversibility of Zn anode achieves a significant improvement with an average Coulombic efficiency of 99.22%at 1 mA cm^(−2)and 0.5 mAh cm^(−2)over 500 cycles.Even at a high Zn utilization rate(depth of discharge,DODZn)of 68%,a steady cycle life up to 200 h is obtained for ultrathin Zn foils(20μm).The superior rate capability and long-term cycle stability of Zn–MnO_(2)full cells further prove the effectiveness of Gly in stabilizing Zn anode.This work sheds light on additive designing from the specific roles of polar groups for AZIBs.
基金The authors acknowledge the funding support from the National Natural Science Foundation of China(U1809220)Zhejiang Provincial Funds for Distinguished Young Scientists of China(LR19E050001)+1 种基金Open Fund Project of Zhijiang Laboratory(2019MC0AB02)Fund for Creative Research Groups of National Natural Science Foundation of China(51821093).
文摘Microfluidic device with patterned microstructures on the substrate surface was used to regulate cell adhesion,morphology,and functions in tissue engineering.We developed a microfluidic device which employing microscale patterned microstructures to achieve enhanced cell adhesion and migration.Biocompatible hydrogel substrates with micro-wavy and lattice-patterned microstructures were fabricated using standing surface acoustic waves and ultraviolet solidification.After seeding the L929 mouse fibroblast cells onto the patterned substrate of the microfluidic device,we determined that the viability and proliferation rate of cell migration can be greatly enhanced.Furthermore,L929 cells showed two types of gathering modes after 48 h of culturing.Cell growth was guided by the patterned substrate used in the microfluidic device and showed differences in the location distribution.Therefore,the developed microfluidic device with patterned microstructures can extend the application of in vitro cell culturing for future drug development and disease diagnosis.
基金the National Standardization Project of TCM(ZYBZH-C-TJ-55)and National Science and Technology Major Project(2018ZX09201011-002).
文摘The negative pressure conical fluidized bed is widely used in the pharmaceutical industry.In this study,experiments based on the negative pressure conical fluidized bed are carried out by changing the material mass and particle size.The pressure fluctuation signals are analyzed by the time and the frequency domain methods.A method for absolutely characterizing the degree of the energy concentration at the main frequency is proposed,where the calculation is to divide the original power spectrum by the average signal power.A phenomenon where the gas velocity curve temporarily stops growing is observed when the material mass is light,and the particle size is small.The standard deviation and kurtosis both rapidly change at the minimum fluidization velocity and thus can be used to determine the flow regime,and the variation rule of the kurtosis is independent of both the material mass and particle size.In the initial fluidization stage,the dominant pressure signal comes from the material movement;with the increase in the gas velocity,the power of a 2.5 Hz signal continues to increase.A method of dividing the main frequency by the average cycle frequency can conveniently determine the fluidized state,and a novel concept called stable fluidized zone proposed in this paper can be obtained.Controlling the gas velocity within the stable fluidized zone ensures that the fluidized bed consistently remains in a stable fluidized state.
基金supported by the National Key Research and Development Program of China(2019YFB1707505)the National Natural Science Foundation of China(Grant No.52005436)。
文摘The trend towards automation and intelligence in aircraft final assembly testing has led to a new demand for autonomous perception of unknown cockpit operation scenes in robotic collaborative airborne system testing.To address this demand,a robotic automated 3D reconstruction cell which enables to autonomously plan the robot end-camera’s trajectory is developed for image acquisition and 3D modeling of the cockpit operation scene.A continuous viewpoint path planning algorithm is proposed that incorporates both 3D reconstruction quality and robot path quality into optimization process.Smoothness metrics for viewpoint position paths and orientation paths are introduced together for the first time in 3D reconstruction.To ensure safe and effective movement,two spatial constraints,Domain of View Admissible Position(DVAP)and Domain of View Admissible Orientation(DVAO),are implemented to account for robot reachability and collision avoidance.By using diffeomorphism mapping,the orientation path is transformed into 3D,consistent with the position path.Both orientation and position paths can be optimized in a unified framework to maximize the gain of reconstruction quality and path smoothness within DVAP and DVAO.The reconstruction cell is capable of automatic data acquisition and fine scene modeling,using the generated robot C-space trajectory.Simulation and physical scene experiments have confirmed the effectiveness of the proposed method to achieve highprecision 3D reconstruction while optimizing robot motion quality.
文摘The pulsed-spray fluid-bed granulation (PSFBG) process was investigated and optimized using definitive scree ning design, a recently proposed new class of three-level desig n of experiment method. Such a design enabled quadratic models to be established that described the effect of six in put process parameters - inlet air temperature, inlet air humidity, binder spray rate, atomization pressure, pulse period, and pulse width - on the granule quality in a PSFBG process. Mathematical models of the mean particle size, relative size distribution width, production yield, and porosity were developed to quantify the relationships between the in flue ncing factors and critical quality attributes. On the basis of con strai nts on the desired granule properties, a design space for PSFBG was determined and ranges of the operating parameters were defined. An acceptable degree of prediction was confirmed by validation experiments, demonstrating the reliability and effectiveness of using definitive screening design to study the PSFBG process. This method can accelerate screening and optimization of this process within a large multidimensional design space.
基金supported by the National Key R&D Program of China(No.2019YFC1509503)the National Natural Science Foundation of China(No.U1809220)the Key Research and Development Program of Zhejiang Province(No.2022C01113),China.
文摘Ultra-thin sheets of titanium for fabricating microchannels have been used in fuel cells due to their good corrosion resistance and high strength-weight ratio. This paper presents a constitutive model for studying the anisotropy effects of pure titanium(CP-Ti) sheet on the springback behavior and forming properties during the microstamping process. Thin sheets of CP-Ti specimens with different orientations were examined using uniaxial tensile tests to assess the effects of anisotropy on their mechanical properties. Then an anisotropic constitutive model considering the off-axis elastic modulus was developed based on orthotropic elasticity and Hill's yield criterion. Numerical modeling and simulation of the microstamping process for fabricating multi-channel structures were performed. The effects of anisotropy on the springback of multi-channels were investigated and compared with experimental results;the effects of tool dimension parameters on the formability of microchannel structures were also analyzed. The results showed that the anisotropy of thin titanium sheets causes various degrees of forming loads and springback in the microstamping of microchannels at different orientations. This study accurately predicts the springback of thin titanium sheet used to fabricate microchannel structures and is a good guide to the formation of such structures.
基金the Fundamental Research Funds for the Central Universities, China (No. 2019FZA4001)
文摘Automated Fiber Placement(AFP)technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However.the unavoidable imperfections induced by the automated layup method bring challenges to the stability of the final mechanical properties of composites.The influence of AFP-induced gaps and overlaps on the modeⅡinterlaminar fracture process of oven-cured laminates is experimentally investigated and explicitly revealed.End-Notched Flexure(ENF)tests were performed to measure the interlaminar fracture toughness of unidirectional laminates under three different defect configurations,namely"Gap""Overlap"and"Gap&Overlap".A marginal decline(about-1.2%in non-precracked tests,-5.1%in precracked tests)and an obvious increase(about 15.2%in nonprecracked tests,5.2%in precracked tests)in fracture toughness were observed for the"Gap"group and the"Overlap"group,respectively.Fractographic studies which involve the metallographic observation and Scanning Electron Microscopy(SEM)observation revealed that the increases in fracture area and crack length helped improve the fracture toughness of the Overlap"group.However,the resin-rich area with high porosity induced by gaps was detrimental to the delamination resistance.To capture the interlaminar stress distribution local to imperfections,a three-dimensional numerical model was established.Gap defects facilitate the local delamination process,and the overlap defect postpones the damage onset and the propagation.
基金funded by the National Key R&D Program of China(Grant No.2018YFB1700700)the National Natural Science Foundation of China(Grant Nos.51935009 and 51821093).
文摘Selective laser melting(SLM)is a unique additive manufacturing(AM)category that can be used to manufacture mechanical parts.It has been widely used in aerospace and automotive using metal or alloy powder.The build orientation is crucial in AM because it affects the as-built part,including its part accuracy,surface roughness,support structure,and build time and cost.A mechanical part is usually composed of multiple surface features.The surface features carry the production and design knowledge,which can be utilized in SLM fabrication.This study proposes a method to determine the build orientation of multi-feature mechanical parts(MFMPs)in SLM.First,the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives.Second,the estimation models of involved optimization objectives are established,and a set of alternative build orientations(ABOs)is further obtained by many-objective optimization.Lastly,a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs.The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process.Two case studies are reported to validate the proposed method with numerical results,and the effectiveness comparison is presented.Physical manufacturing is conducted to prove the performance of the proposed method.The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82,10.84,and 10.62μm,respectively.The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.
基金supported by the National Natural Science Foundation of China(Grant Nos.51775494,51821093,and 51935009)the National Key R&D Program of China(Grant No.2018YFB1700701)+1 种基金the Science and Technology Project of Zhejiang Province,China(Grant No.2019C01141)the Zhejiang Provincial Basic Public Welfare Research Project,China(Grant Nos.LGG18E050007 and LGG21E050020).
文摘Surface accuracy directly affects the surface quality and performance of mechanical parts.Circular hole,especially spatial non-planar hole set is the typical feature and working surface of mechanical parts.Compared with traditional machining methods,additive manufacturing(AM)technology can decrease the surface accuracy errors of circular holes during fabrication.However,an accuracy error may still exist on the surface of circular holes fabricated by AM due to the influence of staircase effect.This study proposes a surface accuracy optimization approach for mechanical parts with multiple circular holes for AM based on triangular fuzzy number(TFN).First,the feature lines on the manifold mesh are extracted using the dihedral angle method and normal tensor voting to detect the circular holes.Second,the optimal AM part build orientation is determined using the genetic algorithm to optimize the surface accuracy of the circular holes by minimizing the weighted volumetric error of the part.Third,the corresponding weights of the circular holes are calculated with the TFN analytic hierarchy process in accordance with the surface accuracy requirements.Lastly,an improved adaptive slicing algorithm is utilized to reduce the entire build time while maintaining the forming surface accuracy of the circular holes using digital twins via virtual printing.The effectiveness of the proposed approach is experimentally validated using two mechanical models.
基金Project supported by the National Natural Science Foundation of China(Nos.72071179 and 51805479)the Natural Science Foundation of Zhejiang Province(No.LY19E050019)the Ministry of Industry and Information Technology of China(No.Z135060009002)。
文摘For efficient use of value stream mapping(VSM)for multi-varieties and small batch production in a data-rich environment enabled by Industry 4.0 technologies,a systematic framework of VSM to rejuvenate traditional lean tools is proposed.It addresses the issue that traditional VSM requires intensive on-site investigation and replies on experience,which hinders decisionmaking efficiency in dynamic and complex environments.The proposed framework follows the data-information-knowledge hierarchy model,and demonstrates how data can be collected in a production workshop,processed into information,and then interpreted into knowledge.In this paper,the necessity and limitations of VSM in automated root cause analysis are first discussed,with a literature review on lean production tools,especially VSM and VSM-based decision making in Industry 4.0.An implementation case of a furniture manufacturer in China is presented,where decision tree algorithm was used for automated root cause analysis.The results indicate that automated VSM can make good use of production data to cater for multi-varieties and small batch production with timely on-site waste identification and analysis.The proposed framework is also suggested as a guideline to renew other lean tools for reliable and efficient decision-making.
基金This work was funded by the National Natural Science Foundation of China(Grant Nos.51775494,51821093,and 51935009)the National Key Research and Development Project(Grant No.2018YFB1700701)Zhejiang Key Research and Development Project(Grant No.2019C01141).
文摘Large-scale cryogenic air separation units(ASUs),which are widely used in global petrochemical and semiconductor industries,are being developed with high operating elasticity under variable working conditions.Different from discrete processes in traditional machinery manufacturing,the ASU process is continuous and involves the compression,adsorption,cooling,condensation,liquefaction,evaporation,and distillation of multiple streams.This feature indicates that thousands of technical parameters in adsorption,heat transfer,and distillation processes are correlated and merged into a large-scale complex system.A lumped parameter model(LPM)of ASU is proposed by lumping the main factors together and simplifying the secondary ones to achieve accurate and fast performance design.On the basis of material and energy conservation laws,the piecewise-lumped parameters are extracted under variable working conditions by using LPM.Takagi–Sugeno(T–S)fuzzy interval detection is recursively utilized to determine whether the critical point is detected or not by using different thresholds.Compared with the traditional method,LPM is particularly suitable for“rough first then precise”modeling by expanding the feasible domain using fuzzy intervals.With LPM,the performance of the air compressor,molecular sieve adsorber,turbo expander,main plate-fin heat exchangers,and packing column of a 100000 Nm3 O2/h large-scale ASU is enhanced to adapt to variable working conditions.The designed value of net power consumption per unit of oxygen production(kW/(Nm3 O2))is reduced by 6.45%.
基金the National Science and Technology Major Project(grant number 2018ZX09201011-002).
文摘Pulsed spray is a useful tool forgranule size control in fluid bed granulation.To improve the quality control of pulsed-spray fluid bed granulation,a combination of in-line near-infrared(NIR)spectroscopy and p「incipal component analysis was used to develop multivariate statistical process control(MSPC)charts.Different types of MSPC charts were developed,including principal component score charts,Hotelling's T2 control charts,and distance to model X control charts,to monitor the batch evolution throughout the granulation process.Correlation optimized warping was used as an alignment method to deal with the time variation in batches caused by the granulation mechanism in MSPC modeling.The control charts developed in this study were validated on normal batches and tested on four batches that deviated from normal processing conditions to achieve real-time fault analysis.The results indicated that the NIR spectroscopy-based MSPC model included the variability in the sample set constituting the model and could withstand external variability.This research demonstrated the application of synchronized NIR spectra in conjunction w让h multivariate batch modeling as an attractive tool for process monitoring and a fault diagnosis method for effective process control in pulsed-spray fluid bed granulation.
基金Project supported by the National Natural Science Foundation of China(No.52075484)the Zhejiang Provincial Funds for Distinguished Young Scientists of China(No.LR19E050001)the Fund for Creative Research Groups of National Natural Science Foundation of China(No.51821093)。
文摘Polymer-based materials with patterned functional particles have been used to develop smart devices with multiple functionalities.This paper presents a novel method to pattern microscale particles into biocompatible polyethylene glycol diacrylate(PEGDA)fluid through a designed surface acoustic wave(SAW)device with slanted-finger interdigital transducers(SFITs).By applying signals of different frequencies,the SFITs can excite SAWs with various wavelengths to pattern the microscale particles.The structural design and working principle of the SAW device with SFITs are firstly presented.To investigate the generation of standing SAWs and pressure field distributions of the SAW device with SFITs,a numerical model was developed.Simulation results showed that different strip-shape patterned pressure fields can be generated,and the period and width of adjacent strips can be adjusted by changing the frequencies of the excitation signals.Experiments were performed to verify that the microscale particles in the PEGDA solution can be successfully patterned into strip-shape patterns with various positions,periods,and widths.The results obtained in this study demonstrate that the developed method of using an SAW device with SFITs can be used for tunable patterning of microscale particles in solutions,and shows great potential for biomedical and microfluidic applications.
基金This work was supported by National Nature Science Foundation of China[51575485]the Natural Science Foundation of Zhejiang Province for Distinguished Young Scientists[LR19E050001]Open Fund Project of Zhejiang Laboratory[2019MC0AB02].
文摘Tactile sensors have been used for haptic perception in intelligent robotics,smart prosthetics,and human-machine interface.The development of multifunctional tactile sensor remains a challenge and limit its application in flexible electronics and devices.We propose a liquid metal based tactile sensor for both temperature and force sensing which is made by 3D printing.The structural design and working principle of liquid metal based tactile sensor are firstly described.A digital light processing-based printing process is developed to print two kinds of photosensitive resins with different hardness,and used to fabricate the tactile sensor.A Wheatstone bridge circuit is designed for decoupling the temperature and forces from the measured output voltages.Characterization tests show that the tactile sensor has relatively high force sensing sensitivity of 0.29 N^(-1),and temperature sensing sensitivities are 0.55%°C−1 at 20~50°C and 0.21%°C^(−1)at 50~80°C,respectively.Then,the fabricated tactile sensor is mounted onto hand finger to measure the contact force and temperature during grasping.Results show that the 3D printed tactile sensor has excellent flexibility and durability and can accurately measure the temperature and contact forces,which demonstrate its potential in robotic manipulation applications.
基金supported by the Fund for Creative Research Groups of National Natural Science Foundation of China (No. 51821093)the National Natural Science Foundation of China (Nos. 52175551, 52075484)(KT and DM)+2 种基金the National Key Research and Development Program (SQ2021YFE010405)(KT)Science Foundation Ireland (SFI) through awards Nos. 15/CDA/3491and 12/RC/2275_P2 (DT)computing resources at the SFI/Higher Education Authority Irish Center for High-End Computing (ICHEC)(SG and DT)
文摘Vectored non-covalent interactions—mainly hydrogen bonding and aromatic interactions—extensively contribute to(bio)-organic self-assembling processes and significantly impact the physicochemical properties of the associated superstructures.However,vectored non-covalent interaction-driven assembly occursmainly along one-dimensional(1D)or three-dimensional(3D)directions,and a two-dimensional(2D)orientation,especially that of multilayered,graphene-like assembly,has been reported less.In this present research,by introducing amino,hydroxyl,and phenyl moieties to the triazine skeleton,supramolecular layered assembly is achieved by vectored non-covalent interactions.The planar hydrogen bonding network results in high stability,with a thermal sustainability of up to about 330°C and a Young’s modulus of up to about 40 GPa.Upon introducing wrinkles by biased hydrogen bonding or aromatic interactions to disturb the planar organization,the stability attenuates.However,the intertwined aromatic interactions prompt a red edge excitation shift effect inside the assemblies,inducing broad-spectrum fluorescence covering nearly the entire visible light region(400–650 nm).We show that bionic,superhydrophobic,pillar-like arrays with contact angles of up to about 170°can be engineered by aromatic interactions using a physical vapor deposition approach,which cannot be realized through hydrogen bonding.Our findings show the feasibility of 2D assembly with engineerable properties by modulating vectored non-covalent interactions.
基金the National Key Research and Development Program of China(No.2022YFE0100800)the National Natural Science Foundation of China(No.52175551)。
文摘Photonic crystals(PCs)exhibit promising structural coloration properties and possess extensive application prospects in diverse optical fields.However,state-of-the-art inorganic or polymeric PCs show limited adaptivity as their configurations are fixed once formed.Herein,bio-organic adaptive PCs are fabricated via drop-casting of amphiphilic guanine-based peptide nucleic acid selfassembled microspheres.The high formation activation energy of up to 81.8 kJ·mol−1 suggests that the self-assembly step dominates the entire process.Therefore,the configurations along with the structural coloration of the supramolecular PCs are sensitive to self-assembly influencing parameters,showing temperature-encoded structural color evolution and solvent polaritydependent solvatochromism.Our findings demonstrate that the supramolecular PCs are adaptive,thus showing promising potential for detection of organic solvents of different polarities in a visual and real-time manner for environmental protection or optical applications.
基金Project supported by the National Natural Science Foundation of China(Nos.51375453 and 51775506)the Natural Science Foundation of Zhejiang Province(No.LY18E050022),China
文摘目的:探究上颌尖牙在不同移动方式下的最佳正畸力。创新点:综合考虑牙周膜的静水压应力和对数应变,进一步优化尖牙移动的最佳正畸力区间。方法:对尖牙施加范围在0~300 g(100 g=0.98 N)的远中向、唇向和拔出向的整体移动力和倾斜移动力,以及范围在0~300 g·mm的绕尖牙牙长轴向的扭转力矩,通过非线性有限元分析对牙周膜的应力应变进行定量评价。约定牙周膜应力在0.47 k Pa(毛细血管压力)至12.8 k Pa(人类心脏收缩压力的80%)之间的为最佳应力;以及牙周膜应变大于0.24%(尖牙最大移动速度时的牙周膜应变的80%)为最佳应变。结论:尖牙倾斜移动时的最佳正畸力范围(远中向为40~44 g,唇向为28~32 g)小于其整体移动(远中向为130~137 g,唇向为110~124 g);尖牙远中向移动时的最佳正畸力范围(整体移动为110~124 g,倾斜移动为28~32 g)小于其唇向移动(整体移动为130~137 g,倾斜移动为40~44 g)。与已有的研究结果相比,最佳正畸力范围进一步缩小,对临床正畸治疗具有较好的指导意义。
