Wearable sensors integrated with deep learning techniques have the potential to revolutionize seamless human-machine interfaces for real-time health monitoring,clinical diagnosis,and robotic applications.Nevertheless,...Wearable sensors integrated with deep learning techniques have the potential to revolutionize seamless human-machine interfaces for real-time health monitoring,clinical diagnosis,and robotic applications.Nevertheless,it remains a critical challenge to simultaneously achieve desirable mechanical and electrical performance along with biocompatibility,adhesion,self-healing,and environmental robustness with excellent sensing metrics.Herein,we report a multifunctional,anti-freezing,selfadhesive,and self-healable organogel pressure sensor composed of cobalt nanoparticle encapsulated nitrogen-doped carbon nanotubes(CoN CNT)embedded in a polyvinyl alcohol-gelatin(PVA/GLE)matrix.Fabricated using a binary solvent system of water and ethylene glycol(EG),the CoN CNT/PVA/GLE organogel exhibits excellent flexibility,biocompatibility,and temperature tolerance with remarkable environmental stability.Electrochemical impedance spectroscopy confirms near-stable performance across a broad humidity range(40%-95%RH).Freeze-tolerant conductivity under sub-zero conditions(-20℃)is attributed to the synergistic role of CoN CNT and EG,preserving mobility and network integrity.The Co N CNT/PVA/GLE organogel sensor exhibits high sensitivity of 5.75 k Pa^(-1)in the detection range from 0 to 20 k Pa,ideal for subtle biomechanical motion detection.A smart human-machine interface for English letter recognition using deep learning achieved 98%accuracy.The organogel sensor utility was extended to detect human gestures like finger bending,wrist motion,and throat vibration during speech.展开更多
A wearable health monitoring system is a promising device for opening the era of the fourth industrial revolution due to increasing interest in health among modern people.Wearable health monitoring systems were demons...A wearable health monitoring system is a promising device for opening the era of the fourth industrial revolution due to increasing interest in health among modern people.Wearable health monitoring systems were demonstrated by several researchers,but still have critical issues of low performance,inefficient and complex fabrication processes.Here,we present the world’s first wearable multifunctional health monitoring system based on flash-induced porous graphene(FPG).FPG was efficiently synthesized via flash lamp,resulting in a large area in four milliseconds.Moreover,to demonstrate the sensing performance of FPG,a wearable multifunctional health monitoring system was fabricated onto a single substrate.A carbon nanotube-polydimethylsiloxane(CNT-PDMS)nanocomposite electrode was successfully formed on the uneven FPG surface using screen printing.The performance of the FPG-based wearable multifunctional health monitoring system was enhanced by the large surface area of the 3D-porous structure FPG.Finally,the FPG-based wearable multifunctional health monitoring system effectively detected motion,skin temperature,and sweat with a strain GF of 2564.38,a linear thermal response of 0.98Ω℃^(-1) under the skin temperature range,and a low ion detection limit of 10μM.展开更多
Carbon nanotube （CNT）was applied in various fields for itssuperior electrical, mechanical and thermal characteristics. After composites were fabricated by extrusion processusing ball-milledCu-CNT powders, mechanical...Carbon nanotube （CNT）was applied in various fields for itssuperior electrical, mechanical and thermal characteristics. After composites were fabricated by extrusion processusing ball-milledCu-CNT powders, mechanicalpropertiesofCu-CNT composites according to CNT fraction were reviewed. CNT （1%, 5% and 10%）,Cu （d=100 nm）, zirconia balls （90 g） and ethanol （20mL） were mixed and dispersed for5h at a speed of 500 r/minusing a planetary ball mill. A billet （d=50 mm, length=100 mm） was made with Cu, and the composite powderswerefilled up into billet using the uni-axial press. In the extrusion process, after the billet was heated at 880℃for1h, specimens were produced in the shape of a round bar using the billet by applying a load of 200 t. The composite powdersweremeasured for particle size byparticlesize distributionequipment. Then the specimen surface fabricated by extrusion was observed by SEM. Mechanicalpropertiesmeasured by the indentation equipment increased with increasing CNT content. The yield strength, tensile strength and hardness of theCu–CNTs composites canbeobviously improved.展开更多
The main objective is to provide an evidence of spatial dependence of mechanical responses of a heterogeneous aluminum brazed joint re-solidified clad, and to confirm a sufficient sensitivity of a nano-indentation—lo...The main objective is to provide an evidence of spatial dependence of mechanical responses of a heterogeneous aluminum brazed joint re-solidified clad, and to confirm a sufficient sensitivity of a nano-indentation—load curve method for identifying the dependence. Topological features of a network of solidification microstructures(α phase and eutectic), formed during quench in a brazing process of aluminum alloy, influence significantly dynamic mechanical responses of resulting heterogeneous material. Nano/micro indentation depth vs load characteristics of differing phases suggest a spatially sensitive mechanical response of a re-solidified fillet in the joint zone. Hence, a spatial distribution, pattern formations and other morphological characteristics of microstructures have a direct impact on an ultimate joint integrity. Topology-induced variations of indentation—load curves was presented. A hypothesis involving microstructures’ spatial distribution vs mechanical response was formulated.展开更多
A new biosi gn al control system that offers the disables the opportunities to control electric appliances is proposed.The four types of signals created by the eyes movements in four directions(up,down,left,and right)...A new biosi gn al control system that offers the disables the opportunities to control electric appliances is proposed.The four types of signals created by the eyes movements in four directions(up,down,left,and right),which are taken as four basic signals , are detected at the forehead.Permutation of 2 signals out of them creates 16 d ifferent signals.Permutation of 3 signals out of them creates 64 signals.They al l amounts to 84 control signals.They are thought to be applicable for the operat ion of some instruments.Furthermore,the dynamic biosignals created by the slow e yes movement is speculated to be applicable for the more convenient control of t hem.展开更多
This paper discusses an optimization of operating a p ermutation circulation-type vehicle routing system (PCVRS, for short), in w hich several stages are located along by a single loop, and a fleet of vehicles travels...This paper discusses an optimization of operating a p ermutation circulation-type vehicle routing system (PCVRS, for short), in w hich several stages are located along by a single loop, and a fleet of vehicles travels on the loop unidirectionally and repeatedly. Traveling on the loop, each vehicle receives an object from the loading stage and then carries it to a cert ain processing stage, or receives an object from a certain processing stage and then carries it to the unloading stage per a turnaround. No passing is allowed f or the vehicles on the loop (from which the system is called permutation, and th is restriction may cause interferences between vehicles). Material handling systems such as PCVRS are actually encountered in flexible man ufacturing systems and in automated storage/retrieval systems. In this paper, we propose a heuristic algorithm for operating the PCVRS, which i ncorporates a new scheduling method for the vehicles with the SPT (shortest proc essing time) numbering of jobs and a round-robin manner of allocating jobs to t he stages, aiming to reduce interferences between the vehicles. We also give num erical results with respect to system performances attained by the heuristic. Description of the system The PCVRS consists of a set of n v vehicles V={V 1,V 2,...,V n v}, a set of n s, processing stages S p={S 1,S 2,...,S n s}, a loading stage S 0 and an unloading stage S n s +1. We denote by S=S p∪{S 0,S n s+l} the set of all the stages. The vehicles travel on a single loop unidirectionany and repeated ly. The system layout is depicted in Fig.1. There is a set of n jobs J={J 1,J 2,...,J n} to be processed b y the vehicles. Each job consists of two tasks: That is, each vehicle receives a n object from S 0 and then carries it to S l with a certain l∈{1,2, ...,n s} (a throw-in job), or receives an object from S l with a certain l∈{1,2,...,n s} and then carries it to S n s+1 (a throw-out job ) per a turnaround. The loop consists of buffer zones BZ(l) and travel zones TZ(l) (see Fig. 1). Each buffer zone BZ(l) is placed in front of stage S l, l=0,1,..., n s, n s+1, in order to avoid a collision between vehicles (i.e., the syste m adopts the so-called zone control strategy). A heuristic algorithm We develop a heuristic algorithm to obtain a good performance for the PCVRS. An operation π={A/B/C} for the PCVRS consists of three decision factors: (A) Numbering jobs Jobs are loaded into S 0 according to an assending order of job numbers. In this paper, we use the following rules to number jobs: SPT: Order jobs in the shortest processing time rule, i.e., P 1≤P 2≤...≤P n for the set of jobs J={J 1,J 2,...,J n}, rather than the FCFS numbering (i.e., number jobs in first-come-first-served order). The SPT rule intends to reduce interferences between two adjacent vehicles at stages. (B) Allocating jobs to stages For the purpose of balancing loads of processing stages, we adopt the following to allocate jobs to the stages: ORDER: Allocate n jobs to n s, processing stages by an in-order manner , i.e., let l(i) be the index of processing stage allocated job J i by ORDER, it holds that l(i)=n s+1-(i-[(i-1)/n s]n s).(1) The ORDER rule intends to process jobs parallel at stages as many as possible. (C) Scheduling vehicles The following method for scheduling vehicles under ORDER rule is already known: Fig.1 The vehicle ro uting system, PCVRS Fig.2 Mean turnaroun d times by heuristics Unchange: Assign n jobs to n v vehicles such that let k(i) be the i ndex of vehicle processing job J i, then k(i)= i-[(i-1)/n v]n v.(2) In csse of n v≥n s, mod (n v,n s)=0 or n v<n s, mod (n s,n v)=0 (mod(x,y) is the remainder of x/y), the number of interferences between vehicles is minimized at stage S 1 under Unchange sche dules, while in the other cases it is not [Lu et al. (2001a)]. Therefore, in t his paper, we develop a new scheduling method of the vehicles, denoted by Ex change, to modify Unchange schedules. Note展开更多
We studied precipitation patterns in a Liesegang system under MW （microwave） irradiation in order to investigate metal salt diffusion in an electrolyte gel. The gel and salt concentrations were varied. MW irradiatio...We studied precipitation patterns in a Liesegang system under MW （microwave） irradiation in order to investigate metal salt diffusion in an electrolyte gel. The gel and salt concentrations were varied. MW irradiation induced periodic patterns of precipitation because polar molecules vibrate and rotate in an electromagnetic field. For example, the number of patterns increased by the irradiation. Accordingly, microwave irradiation nonlinearly accelerated the diffusion of ionic molecules.展开更多
Mechanical computing,utilizing mechanical deformation to perform calculations,has attracted significant attention as an innovative computing strategy for achieving high accuracy and exceptional physical robustness.How...Mechanical computing,utilizing mechanical deformation to perform calculations,has attracted significant attention as an innovative computing strategy for achieving high accuracy and exceptional physical robustness.However,its reliance on passive mechanical displacement limits its applicability for complex computations.This study presents a novel system that enables active light signal modulation through reversible mechanical deformation by integrating soft and 3D electronics.The proposed system features:1)Optical fibers with optimized 3D cracks embedded in a low-modulus,high-elongation material,enabling strain-induced multimodal transitions.2)Maximized stress concentration on the cracked fibers under strain,allowing them to function as active components for light modulation,which facilitates complex logic calculations and validates truth tables.3)Multifunctional vibration sensing capabilities,illustrating the scalability of strain inputs and the potential for dynamic applications,such as soft robotics.These findings underscore the potential of this approach as a computational platform for mechanical motion-based technologies.展开更多
Air mouse has a wide range of uses in robotics,automation,and VR/AR technologies.In this work,the air mouse is prepared using triboelectric sensors,controller units,and machine learning.The triboelectric nanogenerator...Air mouse has a wide range of uses in robotics,automation,and VR/AR technologies.In this work,the air mouse is prepared using triboelectric sensors,controller units,and machine learning.The triboelectric nanogenerator(TENG)performance was optimized by altering the filler’s properties.A dual-ferroelectric crystal system BNKT(xBi_(0.5) Na_(0.5) TiO_(3)-(1−x)Bi_(0.5) K_(0.5) TiO_(3))was prepared with different concentrations(x=_(0.5),0.6,0.7,0.8,and 0.9)to alter the dielectric property.The BNKT-8-based TENG showed a higher performance of 134.04 V and 1.49μA.The prepared device enables to power the small electronic devices such as hygrometers and calculators.Using this TENG device air mouse system with machine learning allows the user to control the mouse pointer in the computer using the smart glove with a high accuracy of 100%.展开更多
Impinging jet arrays are extensively used in numerous industrial operations,including the cooling of electronics,turbine blades,and other high-heat flux systems because of their superior heat transfer capabilities.Opt...Impinging jet arrays are extensively used in numerous industrial operations,including the cooling of electronics,turbine blades,and other high-heat flux systems because of their superior heat transfer capabilities.Optimizing the design and operating parameters of such systems is essential to enhance cooling efficiency and achieve uniform pressure distribution,which can lead to improved system performance and energy savings.This paper presents two multi-objective optimization methodologies for a turbulent air jet impingement cooling system.The governing equations are resolved employing the commercial computational fluid dynamics(CFD)software ANSYS Fluent v17.The study focuses on four controlling parameters:Reynolds number(Re),swirl number(S),jet-to-jet separation distance(Z/D),and impingement height(H/D).The effects of these parameters on heat transfer and impingement pressure distribution are investigated.Non-dominated Sorting Genetic Algorithm(NSGA-II)and Weighted Sum Method(WSM)are employed to optimize the controlling parameters for maximum cooling performance.The aim is to identify optimal design parameters and system configurations that enhance heat transfer efficiency while achieving a uniform impingement pressure distribution.These findings have practical implications for applications requiring efficient cooling.The optimized design achieved a 12.28%increase in convective heat transfer efficiency with a local Nusselt number of 113.05 compared to 100.69 in the reference design.Enhanced convective cooling and heat flux were observed in the optimized configuration,particularly in areas of direct jet impingement.Additionally,the optimized design maintained lower wall temperatures,demonstrating more effective thermal dissipation.展开更多
AIM: To investigate the optimal magnetic pressure and provide a theoretical basis for choledochojejunostomy magnetic compressive anastomosis(magnamosis).METHODS: Four groups of neodymium-iron-boron magnets with differ...AIM: To investigate the optimal magnetic pressure and provide a theoretical basis for choledochojejunostomy magnetic compressive anastomosis(magnamosis).METHODS: Four groups of neodymium-iron-boron magnets with different magnetic pressures of 0.1, 0.2, 0.3 and 0.4 MPa were used to complete the choledochojejunostomy magnamosis. Twenty-six young mongrel dogs were randomly divided into five groups: four groups with different magnetic pressures and 1 group with a hand-suture anastomosis. Serum bilirubin levels were measured in all groups before and 1 wk, 2 wk, 3 wk, 1 mo and 3 mo after surgery. Daily abdominal X-ray fluoroscopy was carried out postoperatively to detect the path and the excretion of the magnet. The animals were euthanized at 1 or 3 mo after the operation, the burst pressure was detected in each anastomosis, and the gross appearance and histology were compared according to the observation.RESULTS: The surgical procedures were all successfully performed in animals. However, animals of group D(magnetic pressure of 0.4 MPa) all experienced complications with bile leakage(4/4), whereas half of animals in group A(magnetic pressure of 0.1 MPa) experienced complications(3/6), 1 animal in the manual group E developed anastomotic stenosis, and animals in group B and group C(magnetic pressure of 0.2 MPa and 0.3 MPa, respectively) all healed well without complications. These results also suggested that the time required to form the stoma was inversely proportional to the magnetic pressure; however, the burst pressure of group A was smaller than those of the other groups at 1 mo(187.5 ± 17.7 vs 290 ± 10/296.7 ± 5.7/287.5 ± 3.5, P < 0.05); the remaining groups did not differ significantly. A histologic examination demonstrated obvious differences between the magnamosis groups and the hand-sewn group.CONCLUSION: We proved that the optimal range for choledochojejunostomy magnamosis is 0.2 MPa to 0.3 MPa, which will help to improve the clinical application of this technique in the future.展开更多
The design of axial or radial swirlers typically governs a number of geometrical parameters that are determined by the desired flow field.In the meantime,the number of unknown parameters increases with the number of c...The design of axial or radial swirlers typically governs a number of geometrical parameters that are determined by the desired flow field.In the meantime,the number of unknown parameters increases with the number of concentrically mounted swirlers.The available literature is nonetheless limited,and designers are obligated to increase the number of initial assumptions.In this article,three kinds of triple swirlers are employed and simulations are performed to determine the effect of each parameter on the swirler performance.Based on the correlation provided,overlengthening the radial vane length could result in significant changes in the flow field from the jetlike pattern to a wide swirl-jet angle due to the Coanda effect.Passage width should also have the potential to alter the swirl-jet angle and velocity field at the exit of the swirler.展开更多
The increasing demand for wearable electronic devices has resulted in tremendous progress in research on energy harvesting and storage devices/technologies.Energy storage devices require a power source to charge them,...The increasing demand for wearable electronic devices has resulted in tremendous progress in research on energy harvesting and storage devices/technologies.Energy storage devices require a power source to charge them,whereas energy harvesting devices require a storage compartment to store the harvested energy for sustainable delivery.Recently,a piezoelectrically driven self-charging supercapacitor power cell(SCSPC)was developed to harvest and store electrical energy in a solitary system to determine the potential impact of these two types of energy devices for wearable electronic applications.This review describes the recent advances in piezoelectric-driven SCSPCs in terms of device configuration,piezoelectric separator,electrolyte types,electrode materials,current collectors,and system integration.This review focuses specifically on the principles and mechanism of the self-charging process that occurred in the SCSPCs and the use of a promising piezo electrochemical spectroscopic tool to realize the piezo electrochemical energy transfer and storage process in the SCSPCs.Further,the current challenges and new perspectives for future developments in the emerging area of SCSPCs or integrated energy devices are discussed.展开更多
Aiming at the problem that the existence of disturbances on the edges of light-stripe makes the segmentation of the light-stripes images difficult, a new segmentation algorithm based on edge-searching is presented. It...Aiming at the problem that the existence of disturbances on the edges of light-stripe makes the segmentation of the light-stripes images difficult, a new segmentation algorithm based on edge-searching is presented. It firstly calculates every edge pixel's horizontal coordinate grads to produce the corresponding grads-edge, then uses a designed length-variable l D template to scan the light-stripes' grads-edges. The template is able to find the disturbances with different width utilizing the distributing character of the edge disturbances. The found disturbances are eliminated finally. The algorithm not only can smoothly segment the light-stripes images, but also eliminate most disturbances on the light-stripes' edges without damaging the light-stripes images' 3D information. A practical example of using the proposed algorithm is given in the end. It is proved that the efficiency of the algorithm has been improved obviously by comparison.展开更多
Drill wear not only affects the surface smoothness of the hole, but also influences the life of the drill. Drill wear state recognition is important in the manufacturing process, which consists of two steps： first, d...Drill wear not only affects the surface smoothness of the hole, but also influences the life of the drill. Drill wear state recognition is important in the manufacturing process, which consists of two steps： first, decomposing cutting torque components from the original signals by wavelet packet decomposition （WPD）; second, extracting wavelet coefficients of different wear states （i.e., slight, normal, or severe wear） with signal features adapting to Welch spectrum. Finally, monitoring and recognition of the feature vectors of cutting torque signal are performed by using the K-means cluster and radial basis function neural network （RBFNN）. The experiments on different tool wears of the multivariable features reveal that the results of monitoring and recognition are significant and effective.展开更多
In mechanical gear systems, dust, noise, vibration, and tooth wear are generated by frictions among gear teeth, and suppressing friction requires lubrication. Magnetic gears transmit torque by magnetic forces without ...In mechanical gear systems, dust, noise, vibration, and tooth wear are generated by frictions among gear teeth, and suppressing friction requires lubrication. Magnetic gears transmit torque by magnetic forces without contact and so avoid contact-related problems. The present paper discusses magnet arrangements and the shape of stationary gear teeth to improve transmission torque in surface magnet type magnetic gear transmission mechanisms.展开更多
Recycling spent lithium-ion batteries(SLIBs)has become essential to preserve the environment and reclaim vital resources for sustainable development.The typical SLIBs recycling concentrated on separating valuable comp...Recycling spent lithium-ion batteries(SLIBs)has become essential to preserve the environment and reclaim vital resources for sustainable development.The typical SLIBs recycling concentrated on separating valuable components had limitations,including high energy consumption and complicated separation processes.This work suggests a safe hydrometallurgical process to recover usable metallic cobalt from depleted LiCoO_(2)batteries by utilizing citric acid as leachant and hydrogen peroxide as an oxidizing agent,with ethanol as a selective precipitating agent.The anode graphite was also recovered and converted to graphene oxide(GO).The above components were directly resynthesized to cobaltintegrated nitrogen-doped graphene(Co@NG).The Co@NG showed a decent activity towards oxygen reduction reaction(ORR)with a half-wave potential of 0.880 V vs.RHE,almost similar to Pt/C(0.888 V vs.RHE)and with an onset potential of 0.92 V vs.RHE.The metal-nitrogen-carbon(Co-N-C)having the highest nitrogen content has decreased the barrier for ORR since the reaction was enhanced for Co@NG-800,as confirmed by density functional theory(DFT)simulations.The Co@NG cathode catalyst coupled with commercial Pt-Ru/C as anode catalyst exhibits excellent performance for direct methanol fuel cell(DMFC)with a peak power density of 34.7 mW cm^(-2)at a discharge current density of120 m A cm^(-2)and decent stability,indicating the promising utilization of spent battery materials in DMFC applications.Besides,lithium was recovered from supernatant as lithium carbonate by coprecipitation process.This work avoids sophisticated elemental separation by utilizing SLIBs for other renewable energy applications,lowering the environmental concerns associated with recycling.展开更多
In this paper,we present a novel algorithm for odometry estimation based on ceiling vision.The main contribution of this algorithm is the introduction of principal direction detection that can greatly reduce error acc...In this paper,we present a novel algorithm for odometry estimation based on ceiling vision.The main contribution of this algorithm is the introduction of principal direction detection that can greatly reduce error accumulation problem in most visual odometry estimation approaches.The principal direction is defned based on the fact that our ceiling is flled with artifcial vertical and horizontal lines which can be used as reference for the current robot s heading direction.The proposed approach can be operated in real-time and it performs well even with camera s disturbance.A moving low-cost RGB-D camera（Kinect）,mounted on a robot,is used to continuously acquire point clouds.Iterative closest point（ICP） is the common way to estimate the current camera position by registering the currently captured point cloud to the previous one.However,its performance sufers from data association problem or it requires pre-alignment information.The performance of the proposed principal direction detection approach does not rely on data association knowledge.Using this method,two point clouds are properly pre-aligned.Hence,we can use ICP to fne-tune the transformation parameters and minimize registration error.Experimental results demonstrate the performance and stability of the proposed system under disturbance in real-time.Several indoor tests are carried out to show that the proposed visual odometry estimation method can help to signifcantly improve the accuracy of simultaneous localization and mapping（SLAM）.展开更多
基金supported by the Basic Science Research Program(2023R1A2C3004336,RS-202300243807)&Regional Leading Research Center(RS-202400405278)through the National Research Foundation of Korea(NRF)grant funded by the Korea Government(MSIT)。
文摘Wearable sensors integrated with deep learning techniques have the potential to revolutionize seamless human-machine interfaces for real-time health monitoring,clinical diagnosis,and robotic applications.Nevertheless,it remains a critical challenge to simultaneously achieve desirable mechanical and electrical performance along with biocompatibility,adhesion,self-healing,and environmental robustness with excellent sensing metrics.Herein,we report a multifunctional,anti-freezing,selfadhesive,and self-healable organogel pressure sensor composed of cobalt nanoparticle encapsulated nitrogen-doped carbon nanotubes(CoN CNT)embedded in a polyvinyl alcohol-gelatin(PVA/GLE)matrix.Fabricated using a binary solvent system of water and ethylene glycol(EG),the CoN CNT/PVA/GLE organogel exhibits excellent flexibility,biocompatibility,and temperature tolerance with remarkable environmental stability.Electrochemical impedance spectroscopy confirms near-stable performance across a broad humidity range(40%-95%RH).Freeze-tolerant conductivity under sub-zero conditions(-20℃)is attributed to the synergistic role of CoN CNT and EG,preserving mobility and network integrity.The Co N CNT/PVA/GLE organogel sensor exhibits high sensitivity of 5.75 k Pa^(-1)in the detection range from 0 to 20 k Pa,ideal for subtle biomechanical motion detection.A smart human-machine interface for English letter recognition using deep learning achieved 98%accuracy.The organogel sensor utility was extended to detect human gestures like finger bending,wrist motion,and throat vibration during speech.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Ministry of Science,ICT and Future Planning(MSIT)(RS-2024-00408989,RS-2023-00278906,and RS-2023-00217661)the Center for Universitywide Research Facilities(CURF)at Jeonbuk National University for High-Resolution In Vivo Micro-Computed Tomography(Skyscan 1276,BRUKER).
文摘A wearable health monitoring system is a promising device for opening the era of the fourth industrial revolution due to increasing interest in health among modern people.Wearable health monitoring systems were demonstrated by several researchers,but still have critical issues of low performance,inefficient and complex fabrication processes.Here,we present the world’s first wearable multifunctional health monitoring system based on flash-induced porous graphene(FPG).FPG was efficiently synthesized via flash lamp,resulting in a large area in four milliseconds.Moreover,to demonstrate the sensing performance of FPG,a wearable multifunctional health monitoring system was fabricated onto a single substrate.A carbon nanotube-polydimethylsiloxane(CNT-PDMS)nanocomposite electrode was successfully formed on the uneven FPG surface using screen printing.The performance of the FPG-based wearable multifunctional health monitoring system was enhanced by the large surface area of the 3D-porous structure FPG.Finally,the FPG-based wearable multifunctional health monitoring system effectively detected motion,skin temperature,and sweat with a strain GF of 2564.38,a linear thermal response of 0.98Ω℃^(-1) under the skin temperature range,and a low ion detection limit of 10μM.
基金supported by the Gyeongsang National University Fund for Professors on Sabbatical Leave (2014)Basic Science Research Program though the National Research Foundation of Korea (NRF)funded by the Ministry of Science, ICT and future Planning (2015R1A2A01004579)
文摘Carbon nanotube （CNT）was applied in various fields for itssuperior electrical, mechanical and thermal characteristics. After composites were fabricated by extrusion processusing ball-milledCu-CNT powders, mechanicalpropertiesofCu-CNT composites according to CNT fraction were reviewed. CNT （1%, 5% and 10%）,Cu （d=100 nm）, zirconia balls （90 g） and ethanol （20mL） were mixed and dispersed for5h at a speed of 500 r/minusing a planetary ball mill. A billet （d=50 mm, length=100 mm） was made with Cu, and the composite powderswerefilled up into billet using the uni-axial press. In the extrusion process, after the billet was heated at 880℃for1h, specimens were produced in the shape of a round bar using the billet by applying a load of 200 t. The composite powdersweremeasured for particle size byparticlesize distributionequipment. Then the specimen surface fabricated by extrusion was observed by SEM. Mechanicalpropertiesmeasured by the indentation equipment increased with increasing CNT content. The yield strength, tensile strength and hardness of theCu–CNTs composites canbeobviously improved.
文摘The main objective is to provide an evidence of spatial dependence of mechanical responses of a heterogeneous aluminum brazed joint re-solidified clad, and to confirm a sufficient sensitivity of a nano-indentation—load curve method for identifying the dependence. Topological features of a network of solidification microstructures(α phase and eutectic), formed during quench in a brazing process of aluminum alloy, influence significantly dynamic mechanical responses of resulting heterogeneous material. Nano/micro indentation depth vs load characteristics of differing phases suggest a spatially sensitive mechanical response of a re-solidified fillet in the joint zone. Hence, a spatial distribution, pattern formations and other morphological characteristics of microstructures have a direct impact on an ultimate joint integrity. Topology-induced variations of indentation—load curves was presented. A hypothesis involving microstructures’ spatial distribution vs mechanical response was formulated.
文摘A new biosi gn al control system that offers the disables the opportunities to control electric appliances is proposed.The four types of signals created by the eyes movements in four directions(up,down,left,and right),which are taken as four basic signals , are detected at the forehead.Permutation of 2 signals out of them creates 16 d ifferent signals.Permutation of 3 signals out of them creates 64 signals.They al l amounts to 84 control signals.They are thought to be applicable for the operat ion of some instruments.Furthermore,the dynamic biosignals created by the slow e yes movement is speculated to be applicable for the more convenient control of t hem.
文摘This paper discusses an optimization of operating a p ermutation circulation-type vehicle routing system (PCVRS, for short), in w hich several stages are located along by a single loop, and a fleet of vehicles travels on the loop unidirectionally and repeatedly. Traveling on the loop, each vehicle receives an object from the loading stage and then carries it to a cert ain processing stage, or receives an object from a certain processing stage and then carries it to the unloading stage per a turnaround. No passing is allowed f or the vehicles on the loop (from which the system is called permutation, and th is restriction may cause interferences between vehicles). Material handling systems such as PCVRS are actually encountered in flexible man ufacturing systems and in automated storage/retrieval systems. In this paper, we propose a heuristic algorithm for operating the PCVRS, which i ncorporates a new scheduling method for the vehicles with the SPT (shortest proc essing time) numbering of jobs and a round-robin manner of allocating jobs to t he stages, aiming to reduce interferences between the vehicles. We also give num erical results with respect to system performances attained by the heuristic. Description of the system The PCVRS consists of a set of n v vehicles V={V 1,V 2,...,V n v}, a set of n s, processing stages S p={S 1,S 2,...,S n s}, a loading stage S 0 and an unloading stage S n s +1. We denote by S=S p∪{S 0,S n s+l} the set of all the stages. The vehicles travel on a single loop unidirectionany and repeated ly. The system layout is depicted in Fig.1. There is a set of n jobs J={J 1,J 2,...,J n} to be processed b y the vehicles. Each job consists of two tasks: That is, each vehicle receives a n object from S 0 and then carries it to S l with a certain l∈{1,2, ...,n s} (a throw-in job), or receives an object from S l with a certain l∈{1,2,...,n s} and then carries it to S n s+1 (a throw-out job ) per a turnaround. The loop consists of buffer zones BZ(l) and travel zones TZ(l) (see Fig. 1). Each buffer zone BZ(l) is placed in front of stage S l, l=0,1,..., n s, n s+1, in order to avoid a collision between vehicles (i.e., the syste m adopts the so-called zone control strategy). A heuristic algorithm We develop a heuristic algorithm to obtain a good performance for the PCVRS. An operation π={A/B/C} for the PCVRS consists of three decision factors: (A) Numbering jobs Jobs are loaded into S 0 according to an assending order of job numbers. In this paper, we use the following rules to number jobs: SPT: Order jobs in the shortest processing time rule, i.e., P 1≤P 2≤...≤P n for the set of jobs J={J 1,J 2,...,J n}, rather than the FCFS numbering (i.e., number jobs in first-come-first-served order). The SPT rule intends to reduce interferences between two adjacent vehicles at stages. (B) Allocating jobs to stages For the purpose of balancing loads of processing stages, we adopt the following to allocate jobs to the stages: ORDER: Allocate n jobs to n s, processing stages by an in-order manner , i.e., let l(i) be the index of processing stage allocated job J i by ORDER, it holds that l(i)=n s+1-(i-[(i-1)/n s]n s).(1) The ORDER rule intends to process jobs parallel at stages as many as possible. (C) Scheduling vehicles The following method for scheduling vehicles under ORDER rule is already known: Fig.1 The vehicle ro uting system, PCVRS Fig.2 Mean turnaroun d times by heuristics Unchange: Assign n jobs to n v vehicles such that let k(i) be the i ndex of vehicle processing job J i, then k(i)= i-[(i-1)/n v]n v.(2) In csse of n v≥n s, mod (n v,n s)=0 or n v<n s, mod (n s,n v)=0 (mod(x,y) is the remainder of x/y), the number of interferences between vehicles is minimized at stage S 1 under Unchange sche dules, while in the other cases it is not [Lu et al. (2001a)]. Therefore, in t his paper, we develop a new scheduling method of the vehicles, denoted by Ex change, to modify Unchange schedules. Note
文摘We studied precipitation patterns in a Liesegang system under MW （microwave） irradiation in order to investigate metal salt diffusion in an electrolyte gel. The gel and salt concentrations were varied. MW irradiation induced periodic patterns of precipitation because polar molecules vibrate and rotate in an electromagnetic field. For example, the number of patterns increased by the irradiation. Accordingly, microwave irradiation nonlinearly accelerated the diffusion of ionic molecules.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(grant Nos.RS-2024-00347619,RS-2024-00406240,RS-2024-00407155,RS-2025-00513522,and RS-2025-25420118)upported by a grant of Korean ARPA-H Project through the Korea Health Industry Development Institute(KHIDI),funded by the Ministry of Health&Welfare,Republic of Korea(grant number:RS-2025-25454431).
文摘Mechanical computing,utilizing mechanical deformation to perform calculations,has attracted significant attention as an innovative computing strategy for achieving high accuracy and exceptional physical robustness.However,its reliance on passive mechanical displacement limits its applicability for complex computations.This study presents a novel system that enables active light signal modulation through reversible mechanical deformation by integrating soft and 3D electronics.The proposed system features:1)Optical fibers with optimized 3D cracks embedded in a low-modulus,high-elongation material,enabling strain-induced multimodal transitions.2)Maximized stress concentration on the cracked fibers under strain,allowing them to function as active components for light modulation,which facilitates complex logic calculations and validates truth tables.3)Multifunctional vibration sensing capabilities,illustrating the scalability of strain inputs and the potential for dynamic applications,such as soft robotics.These findings underscore the potential of this approach as a computational platform for mechanical motion-based technologies.
基金financially supported by the Basic Science Re-search Program(No.RS-2023-NR077252)Regional Leading Re-search Center(No.RS-2024-00405278)through the National Re-search Foundation of Korea(NRF)grant funded by the Korea Gov-ernment(MSIT).
文摘Air mouse has a wide range of uses in robotics,automation,and VR/AR technologies.In this work,the air mouse is prepared using triboelectric sensors,controller units,and machine learning.The triboelectric nanogenerator(TENG)performance was optimized by altering the filler’s properties.A dual-ferroelectric crystal system BNKT(xBi_(0.5) Na_(0.5) TiO_(3)-(1−x)Bi_(0.5) K_(0.5) TiO_(3))was prepared with different concentrations(x=_(0.5),0.6,0.7,0.8,and 0.9)to alter the dielectric property.The BNKT-8-based TENG showed a higher performance of 134.04 V and 1.49μA.The prepared device enables to power the small electronic devices such as hygrometers and calculators.Using this TENG device air mouse system with machine learning allows the user to control the mouse pointer in the computer using the smart glove with a high accuracy of 100%.
文摘Impinging jet arrays are extensively used in numerous industrial operations,including the cooling of electronics,turbine blades,and other high-heat flux systems because of their superior heat transfer capabilities.Optimizing the design and operating parameters of such systems is essential to enhance cooling efficiency and achieve uniform pressure distribution,which can lead to improved system performance and energy savings.This paper presents two multi-objective optimization methodologies for a turbulent air jet impingement cooling system.The governing equations are resolved employing the commercial computational fluid dynamics(CFD)software ANSYS Fluent v17.The study focuses on four controlling parameters:Reynolds number(Re),swirl number(S),jet-to-jet separation distance(Z/D),and impingement height(H/D).The effects of these parameters on heat transfer and impingement pressure distribution are investigated.Non-dominated Sorting Genetic Algorithm(NSGA-II)and Weighted Sum Method(WSM)are employed to optimize the controlling parameters for maximum cooling performance.The aim is to identify optimal design parameters and system configurations that enhance heat transfer efficiency while achieving a uniform impingement pressure distribution.These findings have practical implications for applications requiring efficient cooling.The optimized design achieved a 12.28%increase in convective heat transfer efficiency with a local Nusselt number of 113.05 compared to 100.69 in the reference design.Enhanced convective cooling and heat flux were observed in the optimized configuration,particularly in areas of direct jet impingement.Additionally,the optimized design maintained lower wall temperatures,demonstrating more effective thermal dissipation.
基金the National Natural Science Foundation of China,No.51275387the Project of Development and Innovation Team of Ministry of Education,No.IRT1279the Science and Technology Co-ordination and Innovation Project,Shaanxi Province of China,No.2011KTCQ03-12
文摘AIM: To investigate the optimal magnetic pressure and provide a theoretical basis for choledochojejunostomy magnetic compressive anastomosis(magnamosis).METHODS: Four groups of neodymium-iron-boron magnets with different magnetic pressures of 0.1, 0.2, 0.3 and 0.4 MPa were used to complete the choledochojejunostomy magnamosis. Twenty-six young mongrel dogs were randomly divided into five groups: four groups with different magnetic pressures and 1 group with a hand-suture anastomosis. Serum bilirubin levels were measured in all groups before and 1 wk, 2 wk, 3 wk, 1 mo and 3 mo after surgery. Daily abdominal X-ray fluoroscopy was carried out postoperatively to detect the path and the excretion of the magnet. The animals were euthanized at 1 or 3 mo after the operation, the burst pressure was detected in each anastomosis, and the gross appearance and histology were compared according to the observation.RESULTS: The surgical procedures were all successfully performed in animals. However, animals of group D(magnetic pressure of 0.4 MPa) all experienced complications with bile leakage(4/4), whereas half of animals in group A(magnetic pressure of 0.1 MPa) experienced complications(3/6), 1 animal in the manual group E developed anastomotic stenosis, and animals in group B and group C(magnetic pressure of 0.2 MPa and 0.3 MPa, respectively) all healed well without complications. These results also suggested that the time required to form the stoma was inversely proportional to the magnetic pressure; however, the burst pressure of group A was smaller than those of the other groups at 1 mo(187.5 ± 17.7 vs 290 ± 10/296.7 ± 5.7/287.5 ± 3.5, P < 0.05); the remaining groups did not differ significantly. A histologic examination demonstrated obvious differences between the magnamosis groups and the hand-sewn group.CONCLUSION: We proved that the optimal range for choledochojejunostomy magnamosis is 0.2 MPa to 0.3 MPa, which will help to improve the clinical application of this technique in the future.
基金supported by Korea Electric Power Corporation through Korea Electrical Engineering and Science Research Institute(Grant 18B-022)
文摘The design of axial or radial swirlers typically governs a number of geometrical parameters that are determined by the desired flow field.In the meantime,the number of unknown parameters increases with the number of concentrically mounted swirlers.The available literature is nonetheless limited,and designers are obligated to increase the number of initial assumptions.In this article,three kinds of triple swirlers are employed and simulations are performed to determine the effect of each parameter on the swirler performance.Based on the correlation provided,overlengthening the radial vane length could result in significant changes in the flow field from the jetlike pattern to a wide swirl-jet angle due to the Coanda effect.Passage width should also have the potential to alter the swirl-jet angle and velocity field at the exit of the swirler.
基金National Research Foundation of Korea,Grant/Award Numbers:2020R1A2C2007366,2021R1A4A2000934。
文摘The increasing demand for wearable electronic devices has resulted in tremendous progress in research on energy harvesting and storage devices/technologies.Energy storage devices require a power source to charge them,whereas energy harvesting devices require a storage compartment to store the harvested energy for sustainable delivery.Recently,a piezoelectrically driven self-charging supercapacitor power cell(SCSPC)was developed to harvest and store electrical energy in a solitary system to determine the potential impact of these two types of energy devices for wearable electronic applications.This review describes the recent advances in piezoelectric-driven SCSPCs in terms of device configuration,piezoelectric separator,electrolyte types,electrode materials,current collectors,and system integration.This review focuses specifically on the principles and mechanism of the self-charging process that occurred in the SCSPCs and the use of a promising piezo electrochemical spectroscopic tool to realize the piezo electrochemical energy transfer and storage process in the SCSPCs.Further,the current challenges and new perspectives for future developments in the emerging area of SCSPCs or integrated energy devices are discussed.
基金This project is supported by National Natural Science Foundation of China(No.50275120,No.50535030)Great Science and Technology Project of Xi'an City,China(No.CX200206)
文摘Aiming at the problem that the existence of disturbances on the edges of light-stripe makes the segmentation of the light-stripes images difficult, a new segmentation algorithm based on edge-searching is presented. It firstly calculates every edge pixel's horizontal coordinate grads to produce the corresponding grads-edge, then uses a designed length-variable l D template to scan the light-stripes' grads-edges. The template is able to find the disturbances with different width utilizing the distributing character of the edge disturbances. The found disturbances are eliminated finally. The algorithm not only can smoothly segment the light-stripes images, but also eliminate most disturbances on the light-stripes' edges without damaging the light-stripes images' 3D information. A practical example of using the proposed algorithm is given in the end. It is proved that the efficiency of the algorithm has been improved obviously by comparison.
文摘Drill wear not only affects the surface smoothness of the hole, but also influences the life of the drill. Drill wear state recognition is important in the manufacturing process, which consists of two steps： first, decomposing cutting torque components from the original signals by wavelet packet decomposition （WPD）; second, extracting wavelet coefficients of different wear states （i.e., slight, normal, or severe wear） with signal features adapting to Welch spectrum. Finally, monitoring and recognition of the feature vectors of cutting torque signal are performed by using the K-means cluster and radial basis function neural network （RBFNN）. The experiments on different tool wears of the multivariable features reveal that the results of monitoring and recognition are significant and effective.
文摘In mechanical gear systems, dust, noise, vibration, and tooth wear are generated by frictions among gear teeth, and suppressing friction requires lubrication. Magnetic gears transmit torque by magnetic forces without contact and so avoid contact-related problems. The present paper discusses magnet arrangements and the shape of stationary gear teeth to improve transmission torque in surface magnet type magnetic gear transmission mechanisms.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)the South Korea grant funded by the Korean government(MSIT)(2021R1A4A2000934,2023R1A2C3004336)+1 种基金The computational part of the work was supported by Department of Chemical and Biomolecular Engineering,Institute of Emergent Materials,Sogang University,via NRF Korea grant 2015M3D3A1A01064929a generous supercomputing time from KISTI。
文摘Recycling spent lithium-ion batteries(SLIBs)has become essential to preserve the environment and reclaim vital resources for sustainable development.The typical SLIBs recycling concentrated on separating valuable components had limitations,including high energy consumption and complicated separation processes.This work suggests a safe hydrometallurgical process to recover usable metallic cobalt from depleted LiCoO_(2)batteries by utilizing citric acid as leachant and hydrogen peroxide as an oxidizing agent,with ethanol as a selective precipitating agent.The anode graphite was also recovered and converted to graphene oxide(GO).The above components were directly resynthesized to cobaltintegrated nitrogen-doped graphene(Co@NG).The Co@NG showed a decent activity towards oxygen reduction reaction(ORR)with a half-wave potential of 0.880 V vs.RHE,almost similar to Pt/C(0.888 V vs.RHE)and with an onset potential of 0.92 V vs.RHE.The metal-nitrogen-carbon(Co-N-C)having the highest nitrogen content has decreased the barrier for ORR since the reaction was enhanced for Co@NG-800,as confirmed by density functional theory(DFT)simulations.The Co@NG cathode catalyst coupled with commercial Pt-Ru/C as anode catalyst exhibits excellent performance for direct methanol fuel cell(DMFC)with a peak power density of 34.7 mW cm^(-2)at a discharge current density of120 m A cm^(-2)and decent stability,indicating the promising utilization of spent battery materials in DMFC applications.Besides,lithium was recovered from supernatant as lithium carbonate by coprecipitation process.This work avoids sophisticated elemental separation by utilizing SLIBs for other renewable energy applications,lowering the environmental concerns associated with recycling.
文摘In this paper,we present a novel algorithm for odometry estimation based on ceiling vision.The main contribution of this algorithm is the introduction of principal direction detection that can greatly reduce error accumulation problem in most visual odometry estimation approaches.The principal direction is defned based on the fact that our ceiling is flled with artifcial vertical and horizontal lines which can be used as reference for the current robot s heading direction.The proposed approach can be operated in real-time and it performs well even with camera s disturbance.A moving low-cost RGB-D camera（Kinect）,mounted on a robot,is used to continuously acquire point clouds.Iterative closest point（ICP） is the common way to estimate the current camera position by registering the currently captured point cloud to the previous one.However,its performance sufers from data association problem or it requires pre-alignment information.The performance of the proposed principal direction detection approach does not rely on data association knowledge.Using this method,two point clouds are properly pre-aligned.Hence,we can use ICP to fne-tune the transformation parameters and minimize registration error.Experimental results demonstrate the performance and stability of the proposed system under disturbance in real-time.Several indoor tests are carried out to show that the proposed visual odometry estimation method can help to signifcantly improve the accuracy of simultaneous localization and mapping（SLAM）.
