查看更多>>摘要：4D printed smart materials is mostly relying on thermal stimulation to actuate,limiting their widely application requiring precise and localized control of the deformations.Most existing strategies for achieving localized control rely on hetero-geneous material systems and structural design,thereby increasing design and manufacturing complexity.Here,we endow localized electrothermal,actuation,and sensing properties in electrically-driven soft actuator through parameter-encoded 4D printing.We analyzed the effects of printing parameters on shape memory properties and conductivity,and then explored the multi-directional sensing performance of the 4D printed composites.We demonstrated an integrated actuator-sensor device capable of both shape recovery and perceiving its own position and obstacles simultaneously.Moreover,it can adjust its sensing characteristics through temporary shape programming to adapt to different application scenarios.This study achieves integrated and localized actuation-sensing without the need for multi-material systems and intricate structural designs,offering an efficient solution for the intelligent and lightweight design in the fields of soft robotics,biomedical applications,and aerospace.
查看更多>>摘要：For promising applications such as soft robotics,flexible haptic monitors,and active biomedical devices,it is important to develop ultralow voltage,highly-performant artificial muscles with high bending strains,rapid response times,and superior actuation endurance.We report a novel highly performant and low-cost artificial muscle based on microfibrillated cellulose(MFC),ionic liquid(IL),and polyvinyl alcohol(PVA),The proposed MFC-IL-PVA actuator exhibits excellent electro-chemical performance and actuations characteristics with a high specific capacitance of 225 mF/cm2,a large bending strain of 0.51％,peak displacement up to 7.02 mm at 0.25 V ultra-low voltage,outstanding actuation flexural endurance(99.1％holding rate for 3 h),and a wide frequency band(0.1-5 Hz).These attributes stem mainly from its high specific surface area and porosity,tunable mechanical properties,and the strong ionic interactions of cations and anions with MFC and PVA in ionic liquids.Furthermore,bionic applications such as bionic flytraps,bionic butterflies with vibrating wings,and smart circuit switches have been successfully realized using this technology.These specific bionic applications demonstrate the versatility and potential of the MFC-IL-PVA actuator,highlighting its important role in the fields of bionic engineering,robotics,and smart materials.They open up new possibilities for innovative scientific research and technological applications.
查看更多>>摘要：Soft grippers are favored for handling delicate objects due to their compliance but often have lower load capacities compared to rigid ones.Variable Stiffness Module(VSM)offer a solution,balancing flexibility and load capacity,for which particle jamming is an effective technology for stiffness-tunable robots requiring safe interaction and load capacity.Specific applica-tions,such as rescue scenarios,require quantitative analysis to optimize VSM design parameters,which previous analytical models cannot effectively handle.To address this,a Grey-box model is proposed to analyze the mechanical response of the particle-jamming-based VSM by combining a White-box approach based on the virtual work principle with a Black-box approach that uses a shallow neural network method.The Grey-box model demonstrates a high level of accuracy in predict-ing the VSM force-height mechanical response curves,with errors below 15％in almost 90％of the cases and a maximum error of less than 25％.The model is used to optimize VSM design parameters,particularly those unexplored combinations.Our results from the load capacity and force distribution comparison tests indicate that the VSM,optimized through our methods,quantitatively meets the practical engineering requirements.
查看更多>>摘要：The transistor-inspired Droplet-based Electricity Generator(DEG)significantly enhances the energy collection efficiency from single-position droplets.However,the design of the DEG arrays combining high output performance and large-scale integration under multi-position droplet impacts remains a challenge.Inspired by the unique structure of the honeycomb,we developed an Independent-Cell Droplet-based Electricity Generator(IC-DEG)array that allows for high-efficiency and stable droplet energy harvesting under multi-position droplet impacts.Each independent cell is a transistor-inspired Tubular Droplet-based Electricity Generator(T-DEG),which ensures the high electrical output of the IC-DEG array.The honeycomb-like arrangement improves the space utilization,accelerates the detachment of droplets,and avoids electrical interference among independent cells,all of which further enhance the IC-DEG array performance.The average peak open-circuit voltage of the IC-DEG array is 265.2 V,and 96.6％of peak voltages exceed 200 V,almost double that of a traditional planar array.Moreover,the average droplet detachment time of the IC-DEG array is 44.8 ms,41.4％shorter than the traditional planar array.The enhanced performance of the IC-DEG array is further demonstrated by the high speed of charging capacitors and the capability of driving electronic devices.This study provides a promising design concept for large-scale droplet energy harvesting devices.
查看更多>>摘要：The Auxetic Structure(AS)exhibits significant densification strain due to its concave cell architecture,functioning as an effective energy-absorbing metamaterial.However,its limited plateau stress hampers further enhancement of energy absorption.The deep-sea Glass Sponge(GS)has high plateau stress due to its diagonal braces.Inspired by GS,the Glass-Sponge-Auxetic Structure(GSAS)is proposed,featuring concave cells reinforced by diagonal braces to achieve both high plateau stress and densification strain.Different structural configurations incorporating various brace arrangements and thicknesses for GSAS are designed and compared through finite element analysis.An optimal GSAS is achieved with a 0.5 mm strut thickness and an asymmetric arrangement of crossing and uncrossing braces.The GSAS is fabricated using Ti6A14V through selective laser melting and compared with AS,GS,body-centered cube,and honeycomb in compression tests.The unique bending-stretching deformation and non-simultaneous fracturing pattern results in simultaneous high plateau stress and densification strain,and the highest energy absorption and specific energy absorption.Compared to AS,these values are enhanced by 156％and 75％,respectively.The exceptional energy absorption capability of GSAS presents promising prospects in fields such as automobile collision avoidance and vibration damping,with its customizable cell numbers offering the potential for more specific applications.
查看更多>>摘要：Hammer mill is widely used in the feed processing industry.During its operation,the material is thrown against the inner wall of the sieve after being broken by the hammer.Limited by the annular structure sieve,the grinded material tends to produce a"air-material circulation layer"on the inner wall of the sieve,leading to problems such as low grinding efficiency and high grinding energy consumption.Considering the disruptive characteristics of the special profile structure of a pigeon's wing on the airflow field,we extract the geometric characteristics of the coupling element and optimize the related structural parameters.Based on the principles of bionics,a new wing sieve is then designed,and its efficient grinding mechanism is studied.Compared to the commercial sieve,the experimental results indicate the bio-inspired sieve can significantly improve the material productivity and grinding quality.
查看更多>>摘要：The In Vitro Bionic Digestion Model(IVBDM)are used to simulate the digestion process of food or pharmaceuticals in corresponding digestion tracts for obtaining the digestion data,which are expected to replace in vivo experiments with ani-mals in the early stages of functional food or drug development,and thus have broad applications prospects.However,little is known so far about how the factors including the Young's modulus of the model,the level,location and direction of the applied load,affect the peristalsis amplitude of the IVBDM.Based on an In Vitro Bionic Rat Stomach Model(IVBRSM),simulation and experimental analysis were conducted to examine the factors effecting the peristalsis amplitude of the IVBRSM.It is shown that Young's modulus of the model significantly affects the peristalsis amplitude,with lower Young's modulus resulting in larger amplitude.Load level,location,and direction also influence the peristalsis amplitude.Addition-ally,IVBRSM size and wall thickness play a role,with larger models requiring higher load levels or lower Young's modulus for the same peristalsis amplitude.Simulation data correlate well with experimental results.These findings contribute to the understanding of the peristalsis state of IVBRSM under different conditions and can guide the design and fabrication of such in vitro bionic digestion models.
查看更多>>摘要：Butterfly coloration originates from the finely structured scales grown on the underlying wing cuticle.Most researchers who study butterfly scales are focused on the static optic properties of cover scales,with few works referring to dynamic optical properties of the scales.Here,the dynamic coloration effect of the multiple scales was studied based on the mea-surements of varying-angle reflection and the characterization of scale flexibility in two species of Lycaenid,Plebejus argyrognomon with violet wings and Polyommatus erotides with blue wings.We explored the angle-dependent color changeability and the color-mediating efficiency of wing scales.It was found that the three main kinds of flexible scales(cover,ground and androconia scales)were asynchronously bent during wing rotation,which caused the discoloration effect.The three layers of composite scales broaden the light signal when compared to the single scale,which may be of great significance to the recognition of insects.Specifically,the androconia scales were shown to strongly contribute to the overall wing coloration.The cover scale coloration was ascribed to the coherence scattering resulted from the short-range order at intermediate spatial frequencies from the 2D Fourier power spectra.Our findings are expected to deepen the understanding of the complex characteristics of biological coloration and to provide new inspirations for the fabrication of biomimetic flexible discoloration materials.
查看更多>>摘要：This paper systematically studies the movement behavior changes of Camponotus japonicus under one or two leg injuries.Firstly,a linear motion channel matching the size of the ants'legs was designed,and the movements of ants with different leg injuries were captured using high-speed cameras,constructing a comprehensive video dataset of ants'movements with missing legs.Secondly,stable and reliable motion position information for keypoints on the ants'bodies and legs was obtained by utilizing low-annotation biometric keypoint detection technology.Finally,by analyzing the filtered gait data,information about the changes in the step locational points areas,phase differences,and duty factors of the injured ants'remaining legs was obtained.Comparative analysis of the ants'gait characteristics revealed some common adjustment patterns when the ants were in the injured states.Additionally,the study found that the loss of a foreleg had a significant impact on the ants'movement.When two legs were missing,the loss of both legs on the same side had a greater effect on movement,whereas symmetric opposite-side leg loss conditions had a lesser impact.The research will provide an important reference for the subsequent design of gait adjustment algorithms for biomimetic multi-legged robots under damaged conditions.
查看更多>>摘要：With the increasing dimensionality of the data,High-dimensional Feature Selection(HFS)becomes an increasingly dif-ficult task.It is not simple to find the best subset of features due to the breadth of the search space and the intricacy of the interactions between features.Many of the Feature Selection(FS)approaches now in use for these problems perform sig-nificantly less well when faced with such intricate situations involving high-dimensional search spaces.It is demonstrated that meta-heuristic algorithms can provide sub-optimal results in an acceptable amount of time.This paper presents a new binary Boosted version of the Spider Wasp Optimizer(BSWO)called Binary Boosted SWO(BBSWO),which combines a number of successful and promising strategies,in order to deal with HFS.The shortcomings of the original BSWO,including early convergence,settling into local optimums,limited exploration and exploitation,and lack of population diversity,were addressed by the proposal of this new variant of SWO.The concept of chaos optimization is introduced in BSWO,where initialization is consistently produced by utilizing the properties of sine chaos mapping.A new convergence parameter was then incorporated into BSWO to achieve a promising balance between exploration and exploitation.Multiple exploration mechanisms were then applied in conjunction with several exploitation strategies to effectively enrich the search process of BSWO within the search space.Finally,quantum-based optimization was added to enhance the diversity of the search agents in BSWO.The proposed BBSWO not only offers the most suitable subset of features located,but it also lessens the data's redundancy structure.BBSWO was evaluated using the k-Nearest Neighbor(k-NN)classifier on 23 HFS problems from the biomedical domain taken from the UCI repository.The results were compared with those of traditional BSWO and other well-known meta-heuristics-based FS.The findings indicate that,in comparison to other competing techniques,the proposed BBSWO can,on average,identify the least significant subsets of features with efficient classification accuracy of the k-NN classifier.
万方数据