Preparation of MXene-based hybrids and their application in neuromorphic devices

The traditional von Neumann computing architecture has relatively-low information processing speed and high power consumption,making it difficult to meet the computing needs of artificial intelligence(AI).Neuromorphic computing systems,with massively parallel computing capability and low power consumption,have been considered as an ideal option for data storage and AI computing in the future.Memristor,as the fourth basic electronic component besides resistance,capacitance and inductance,is one of the most competitive candidates for neuromorphic computing systems benefiting from the simple structure,continuously adjustable conductivity state,ultra-low power consumption,high switching speed and compatibility with existing CMOS technology.The memristors with applying MXene-based hybrids have attracted significant attention in recent years.Here,we introduce the latest progress in the synthesis of MXene-based hybrids and summarize their potential applications in memristor devices and neuromorphological intelligence.We explore the development trend of memristors constructed by combining MXenes with other functional materials and emphatically discuss the potential mechanism of MXenes-based memristor devices.Finally,the future prospects and directions of MXene-based memristors are briefly described.

Dynamic microphysiological system chip platform for high-throughput,customizable,and multi-dimensional drug screening

Spheroids and organoids have attracted significant attention as innovative models for disease modeling and drug screening.By employing diverse types of spheroids or organoids,it is feasible to establish microphysiological systems that enhance the precision of disease modeling and offer more dependable and comprehensive drug screening.High-throughput microphysiological systems that support optional,parallel testing of multiple drugs have promising applications in personalized medical treatment and drug research.However,establishing such a system is highly challenging and requires a multidisciplinary approach.This study introduces a dynamic Microphysiological System Chip Platform(MSCP)with multiple functional microstructures that encompass the mentioned advantages.We developed a high-throughput lung cancer spheroids model and an intestine-liverheart-lung cancer microphysiological system for conducting parallel testing on four anti-lung cancer drugs,demonstrating the feasibility of the MSCP.This microphysiological system combines microscale and macroscale biomimetics to enable a comprehensive assessment of drug efficacy and side effects.Moreover,the microphysiological system enables evaluation of the real pharmacological effect of drug molecules reaching the target lesion after absorption by normal organs through fluid-based physiological communication.The MSCP could serves as a valuable platform for microphysiological system research,making significant contributions to disease modeling,drug development,and personalized medical treatment.

Tuning heterogeneous microstructures to enhance mechanical properties of nano-TiN particle reinforced Haynes 230 composites by laser powder bed fusion

Laser powder bed fusion(LPBF)is considered to be one of the most promising additive manufacturing technologies for producing components with geometries and high geometrical precision that are unattainable by traditional technologies.The superalloy exhibits exceptional mechanical and high-temperature performances,rendering it a prime candidate for advanced aero-engine applications.Despite the high demand for LPBF-manufactured superalloys,the superalloy is one of the materials manufactured difficultly by LPBF due to their large laser absorptivity fluctuation,poor molten pool stability and sharp temperature gradient.Hence,superalloys are characterized by severe pores,undesirable coarse columnar grains and poor mechanical properties.In this work,the effect of nano-TiN particles on defects,molten pool characteristics and microstructure and performance of the composites were investigated.The 4.5 wt%TiN/Haynes230 samples exhibited exceptional nanohardness and elastic modulus with maximum values reaching 5.53 GPa and 240.03 GPa,respectively.These superior mechanical properties were attributed to the combined effects of spatter and gas pore inhibition,grain refinement and duplex nanophases strengthening.Moreover,the stability of molten pool was enhanced,and spatter was effectively suppressed by adding nano-TiN particles,while grain refinement and columnar to equiaxed transitions were promoted.Furthermore,the matrix exhibited a high dislocation density due to a significant hindrance of dislocation movement caused by massive nano-phases(e.g.,TiN and M_(23)C_(6)),resulting in the formation of extensive dislocation tangles and rings.This work offers novel insights into the role of nanoparticles reinforced superalloy composites by LPBF.

Knowledge Reasoning Method Based on Deep Transfer Reinforcement Learning:DTRLpath

In recent years,with the continuous development of deep learning and knowledge graph reasoning methods,more and more researchers have shown great interest in improving knowledge graph reasoning methods by inferring missing facts through reasoning.By searching paths on the knowledge graph and making fact and link predictions based on these paths,deep learning-based Reinforcement Learning(RL)agents can demonstrate good performance and interpretability.Therefore,deep reinforcement learning-based knowledge reasoning methods have rapidly emerged in recent years and have become a hot research topic.However,even in a small and fixed knowledge graph reasoning action space,there are still a large number of invalid actions.It often leads to the interruption of RL agents’wandering due to the selection of invalid actions,resulting in a significant decrease in the success rate of path mining.In order to improve the success rate of RL agents in the early stages of path search,this article proposes a knowledge reasoning method based on Deep Transfer Reinforcement Learning path(DTRLpath).Before supervised pre-training and retraining,a pre-task of searching for effective actions in a single step is added.The RL agent is first trained in the pre-task to improve its ability to search for effective actions.Then,the trained agent is transferred to the target reasoning task for path search training,which improves its success rate in searching for target task paths.Finally,based on the comparative experimental results on the FB15K-237 and NELL-995 datasets,it can be concluded that the proposed method significantly improves the success rate of path search and outperforms similar methods in most reasoning tasks.

Equivalent protection factor of bi-layer ceramic metal structures

With increasing ballistic threat levels,there is ever more demand on developing ceramic armor designs with improved performance.This paper presents finite element simulations that investigate the performance of silicon carbide ceramic with steel 4340 backing material and titanium alloy,graphite as buffer layers when subjected to normal and oblique impacts by a tungsten alloy long rod projectile(LRP).Depth of penetration from experimental measurements is compared with simulations to confirm the validity of constitutive,failure model parameters.Titanium alloy cover plate and graphite interface weak layer laterally spread the impact shock away from the SiC tile and reduces the amplification of the stress accumulation at the front surface of the SiC tile.The dwelling time increases before it penetrates into ceramic armor.Further,using AUTODYN®numerical simulations detailed parametric study is carried out to identify the minimum areal density armor for a given ballistic limit velocity.The equivalent protection factor for the bi-layer armor is a simple function of the cosine of the angle of impact.

Development of augmented reality serious games with a vibrotactile feedback jacket

Background In the past few years,augmented reality(AR)has rapidly advanced and has been applied in different fields.One of the successful AR applications is the immersive and interactive serious games,which can be used for education and learning purposes.Methods In this project,a prototype of an AR serious game is developed and demonstrated.Gamers utilize a head-mounted device and a vibrotactile feedback jacket to explore and interact with the AR serious game.Fourteen vibration actuators are embedded in the vibrotactile feedback jacket to generate immersive AR experience.These vibration actuators are triggered in accordance with the designed game scripts.Various vibration patterns and intensity levels are synthesized in different game scenes.This article presents the details of the entire software development of the AR serious game,including game scripts,game scenes with AR effects design,signal processing flow,behavior design,and communication configuration.Graphics computations are processed using the graphics processing unit in the system.Results/Conclusions The performance of the AR serious game prototype is evaluated and analyzed.The computation loads and resource utilization of normal game scenes and heavy computation scenes are compared.With 14 vibration actuators placed at different body positions,various vibration patterns and intensity levels can be generated by the vibrotactile feedback jacket,providing different real-world feedback.The prototype of this AR serious game can be valuable in building large-scale AR or virtual reality educational and entertainment games.Possible future improvements of the proposed prototype are also discussed in this article.

Application of ultrasonic fatigue technology in very-high-cycle fatigue testing of aviation gas turbine engine blade materials:A review

The need for very-high-cycle fatigue(VHCF)testing up to 1010cycles of aviation gas turbine engine blade materials under combined mechanical loads and complex environments has encouraged the development of VHCF testing instrumentation and technology.This article begins with a comprehensive review of the existing available techniques that enable VHCF testing.Recent advances in ultrasonic fatigue testing(UFT)techniques are highlighted,containing their new capabilities and methods for single load,multiaxial load,variable amplitude fatigue,and combined cycle fatigue.New techniques for conducting UFT in high-temperature,humid environments,and corrosive environments are summarized.These developments in mechanical loading and environmental building techniques provide the possibility of laboratory construction for real service conditions of blade materials.New techniques that can be used for in situ monitoring of VHCF damage are summarized.Key issues in the UFT field are presented,and countermeasures are collated.Finally,the existing problems and future trends in the field are briefly described.

Collision risk assessment of reduced aircraft separation minima in procedural airspace using advanced communication and navigation

With the advancement of Communication,Navigation and Surveillance(CNS)technolo-gies such as space-based Automatic Dependent Surveillance-Broadcast/Contract(ADS-B/C),large separation minima may be reduced in procedural airspaces.It is of great significance to know the upper limit of the Reduced Separation Minima(RSM)for a procedural airspace and the corre-sponding consequences on collision risk with specifics of the advanced ADS-B and control interven-tion model.In this work,an interactive software is first developed for collision risk estimation.This software integrates the International Civil Aviation Organization(ICAO)collision risk models for lateral and longitudinal collision risk calculation for the Singapore procedural airspace.Results demonstrate that the lateral and longitudinal collision risk of Singapore procedural airspace with respect to current control procedures meets the ICAO Target Level of Safety(TLS)standard.Moreover,the feasibility of reducing the horizontal separations implemented in the Singapore pro-cedural airspace with respect to advanced CNS techniques is investigated.It is found that if advanced CNS technologies are applied,then the current 50-NM lateral and longitudinal separa-tion standards can be reduced to 22 NM(1 NM=1.825 km)and 20 NM,respectively,to meet the TLS standards based on current demand.A method is then devised to expand the traffic demand by p for p∈[10%,200%].It is found that the minimum lateral and longitudinal separa-tions can be reduced from 50 NM to be within the range of[23,31]NM,and 20 NM,respectively,for p∈[10%,200%],while the collision risk still meets the TLS standards.

Single-pilot operations in commercial flight:Effects on neural activity and visual behaviour under abnormalities and emergencies

With cutting-edge technologies and considering airline human-resource-saving,a single pilot in commercial jets could be technically feasible.Investigating changes in captains’natural behaviours are initially required to comprehend the specific safe human performance envelope for safeguarding single-pilot flight,particularly in high-risk situations.This paper investigates how captains’performance transforms for fixing emergencies when operating from Dual-Pilot Operations(DPO)to Single-Pilot Operations(SPO)through a physiological-based approach.Twenty pilots flew an emergency-included flight with/without first officers’assistance.The neural activities and scanning behaviours were recorded using a 32-channel Electroencephalogram(EEG)and glasses-based eye tracker,with the observation and post-experiment questionnaires to evaluate the flight operations and pilots’perception.Flying alone,there was a significantly increased cortical activity in h and b waves over the frontal,parietal,and temporal lobes during the more complicated emergencies,and pilots focused less on the primary flight display while spending significantly more time scanning the other interfaces.The physiological fluctuating patterns associated with risky operations in SPO were highlighted by cross-correlating multimodal data.The experimental-based noteworthy insights may wish to inform commercial SPO measures to lessen the persistent physiological fluctuation,assisting airlines in creating SPO-oriented intelligent flight systems to give captains adequate support for assuring safer air transportation.

Multiscale analysis of friction behavior at fretting interfaces

Friction behavior at fretting interfaces is of fundamental interest in tribology and is important in material applications.However,friction has contact intervals,which can accurately determine the friction characteristics of a material;however,this has not been thoroughly investigated.Moreover,the fretting process with regard to different interfacial configurations have also not been systematically evaluated.To bridge these research gaps,molecular dynamics(MD)simulations on Al–Al,diamond–diamond,and diamond–silicon fretting interfaces were performed while considering bidirectional forces.This paper also proposes new energy theories,bonding principles,nanoscale friction laws,and wear rate analyses.With these models,semi-quantitative analyses of coefficient of friction(CoF)were made and simulation outcomes were examined.The results show that the differences in the hardness,stiffness modulus,and the material configuration have a considerable influence on the fretting process.This can potentially lead to the force generated during friction contact intervals along with changes in the CoF.The effect of surface separation can be of great significance in predicting the fretting process,selecting the material,and for optimization.

Joint Estimation of Inconsistency and State of Health for Series Battery Packs

Battery packs are applied in various areas(e.g.,electric vehicles,energy storage,space,mining,etc.),which requires the state of health(SOH)to be accurately estimated.Inconsistency,also known as cell variation,is considered a significant evaluation index that greatly affects the degradation of battery pack.This paper proposes a novel joint inconsistency and SOH estimation method under cycling,which fills the gap of joint estimation based on the fast-charging process for electric vehicles.First,fifteen features are extracted from current change points during the partial charging process.Then,a joint estimation system is designed,where fusion weights are obtained by the analytic hierarchy process and multi-scale sample entropy to evaluate inconsistency.A wrapper is used to select the optimal feature subset,and Gaussian process regression is implemented to estimate the SOH.Finally,the estimation performance is assessed by the test data.The results show that the inconsistency evaluation can reflect the aging conditions,and the inconsistency does affect the aging process.The wrapper selection method improves the accuracy of SOH estimation by about 75.8%compared to the traditional filter method when only 10%of data is used for model training.The maximum absolute error and root mean square error are 2.58%and 0.93%,respectively.

Scaling relationships of elastic-perfectly plastic film/coating materials from small scale sharp indentation

The scaling relationships of elastic-perfectly plastic film/coating materials during sharp indentation have been obtained using dimensional analysis and finite-element modeling. Besides the bulk substrate materials, a wide range of film/coating materials with different ratios in term of the Young’s modulus and yield strength were examined, namely different values of Ef/Esand Yf/Es.Based on these scaling relationships, the substrate effects on indentation response and deformed surface profile of residual imprint are given. Furthermore, the scaling relationship among the work of indentation, reduced elastic modulus and hardness has been found. It is found that the ratio of the indentation hardness to measurement of substrate elastic modulus could be used to characterize the wear resistance of film/coating materials. In addition, a novel method to acquire the intrinsic hardness and elastic modulus of film/coating materials is proposed combined with the well-known 10% critical indentation depth rule, which avoids the error caused by estimating the contact area. This work could be contributed for characterizing the mechanical properties of film/coating materials at micro-and nanoscale.

Femtosecond laser-induced surface wettability modification of polystyrene surface

In this paper, we demonstrated a simple method to create either a hydrophilic or hydrophobic surface. With femtosecond laser irradiation at different laser parameters, the water contact angle (WCA) on polystyrene’s surface can be modified to either 12.7° or 156.2° from its original WCA of 88.2°. With properly spaced micro-pits created, the surface became hydrophilic probably due to the spread of the water droplets into the micro-pits. While with properly spaced micro-grooves created, the surface became rough and more hydrophobic. We investigated the effect of laser parameters on WCAs and analyzed the laser-treated surface roughness, profiles and chemical bonds by surface profilometer, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). For the laser-treated surface with low roughness, the polar (such as C—O, C=O, and O—C=O bonds) and non-polar (such as C—C or C—H bonds) groups were found to be responsible for the wettability changes. While for a rough surface, the surface roughness or the surface topography structure played a more significant role in the changes of the surface WCA. The mechanisms involved in the laser surface wettability modification process were discussed.

Additive manufacturing of composite materials and functionally graded structures using selective heat melting technique

The feasibility of using selective heat melting(SHM) to fabricate composite materials and functionally graded structures was investigated.We report,for the first time,the successful 3 D printing of copper(Cu)-polyethylene(PE) composite,iron(Fe)-polyethylene(PE) composite and functionally graded CuO foams using the SHM technique.It was found that a low feed rate,high airflow rate and high airflow temperature were required for efficient delivery of heat from the emitted hot air to the powder bed,so that the PE binder particles can melt and form dense composites with smooth surfaces.The best mechanical properties were exhibited by composites with 80 vol.% PE,as lower PE concentrations led to deficient binding of the metal particles,while higher PE concentrations meant that very few metal particles were available to strengthen the composite.The strength exhibited by Cu-PE composites was comparable to engineering plastics such as polycarbonate,with the added advantage of being electrically conductive.The average conductivity of the samples,0.152±0.28 S/m,was on par with physically crosslinked graphene assemblies.By subjecting a Cu-PE composite,with Cu concentration graded from 10 vol.% to 30 vol.%,to a high temperature debinding and sintering treatment in air,CuO foam with graded porosity can be obtained.This CuO foam was observed to fail in a layer-by-layer manner under mechanical compression,which is a characteristic of functionally graded materials.Our study shows that,compared to existing 3 D printing techniques,SHM can be cheaper,have wider material compatibility,occupy a smaller footprint and potentially induce less residual stresses in the fabricated parts.Therefore,it could be a valuable complement to current additive manufacturing techniques for fabricating mechanically strong composite materials and functionally graded structures.

Investigation of spoilage in salmon by electrochemical impedance spectroscopy and time-domain terahertz spectroscopy

In this study,Spoilage of salmon was investigated using electrochemical impedance spectroscopy(EIS)and ter-ahertz time-domain spectroscopy(TDS).Salmon tissues were continuously observed for more than 20 h,from fresh to full spoilage.The complex impedance(Z)and phase shift(θ)of the salmon samples were derived based on the EIS signal.Critical frequency changes,phase shifts,and impedance variations with time at different fre-quencies were extracted from the data and used as indicators of the freshness of salmon.In the THz TDS analysis,time-domain spectra were recorded in transmission and reflection modes.Four stages of fish spoilage were clearly observed in both the EIS and THz TDS spectra.Although EIS is more sensitive under the current experimental conditions,THz TDS in reflection mode provides a non-invasive and non-destructive way to monitor salmon spoilage,which is practically beneficial for the food quality control industry.

Characterizing the human-robot haptic dyad in robot therapy of stroke survivors

Purpose–The working hypothesis,on which this paper is built,is that it is advantageous to look at protocols of robot rehabilitation in the general context of human-robot interaction in haptic dyads.The purpose of this paper is to propose a new method to detect and evaluate an index of active participation(AC index),underlying the performance of robot-assisted movements.This is important for avoiding the slacking phenomenon that affects robot therapy.Design/methodology/approach–The evaluation of the AC index is based on a novel technique of assistance which does not use constant or elastic forces but trains of small force impulses,with amplitude adapted to the level of impairment and a frequency of 2 Hz,which is suggested by recent results in the field of intermittent motor control.A preliminary feasibility test of the proposed method was carried out during a haptic reaching task in the absence of visual feedback,for a group of five stroke patients and an equal group of healthy subjects.Findings–The AC index appears to be stable and sensitive to training in both populations of subjects.Originality/value–The main original element of this study is the proposal of the new AC index of voluntary control associated with the new method of pulsed haptic interaction.