Considering the secure authentication problem for equipment support information network,a clustering method based on the business information flow is proposed. Based on the proposed method,a cluster-based distributed ...Considering the secure authentication problem for equipment support information network,a clustering method based on the business information flow is proposed. Based on the proposed method,a cluster-based distributed authentication mechanism and an optimal design method for distributed certificate authority( CA)are designed. Compared with some conventional clustering methods for network,the proposed clustering method considers the business information flow of the network and the task of the network nodes,which can decrease the communication spending between the clusters and improve the network efficiency effectively. The identity authentication protocols between the nodes in the same cluster and in different clusters are designed. From the perspective of the security of network and the availability of distributed authentication service,the definition of the secure service success rate of distributed CA is given and it is taken as the aim of the optimal design for distributed CA. The efficiency of providing the distributed certificate service successfully by the distributed CA is taken as the constraint condition of the optimal design for distributed CA. The determination method for the optimal value of the threshold is investigated. The proposed method can provide references for the optimal design for distributed CA.展开更多
Integrated perovskite-organic solar cells(IPOSCs) offer a promising hybrid approach that combines the advantages of perovskite and organic solar cells, enabling efficient photon absorption across a broad spectrum with...Integrated perovskite-organic solar cells(IPOSCs) offer a promising hybrid approach that combines the advantages of perovskite and organic solar cells, enabling efficient photon absorption across a broad spectrum with a simplified architecture. However, challenges such as limited charge mobility in organic bulk heterojunction(BHJ) layers, and energy-level mismatch at the perovskite/BHJ interface still sustain. Recent advancements in non-fullerene acceptors(NFAs), interfacial engineering, and emerging materials have improved charge transfer/transport, and overall power conversion efficiency(PCE) of IPOSCs.This review explores key developments in IPOSCs, focusing on low-bandgap materials for near-infrared absorption, energy alignment optimization, and strategies to enhance photocurrent density and device performance. Future innovations in material selection and device architecture will be crucial for further improving the efficiency of IPOSCs, bringing them closer to practical application in next-generation photovoltaic technologies.展开更多
Commonly,the standards for the geometric design of roads refer to a given set of values for the friction coefficient(longitudinal and transverse friction).These"reference"values imply corresponding visibilit...Commonly,the standards for the geometric design of roads refer to a given set of values for the friction coefficient(longitudinal and transverse friction).These"reference"values imply corresponding visibility sights,curvature radii,and speed limits.Unfortunately,not only do these reference values not correspond to a given standard to measure them,but nothing is said about the decrease of the posted speed limit(variable speed limits)when roads become slippery and lanes for autonomous vehicle(AV)are concerned.Furthermore,the same assessment of the friction coefficient has plenty of uncertainties due to measurement device,temperature,location,time passed from the construction,alignment-related variables(e.g.,curve,tangent,transition curve,convexity/crests or concavity/sags,longitudinal slope,superelevation,and ruling gradient),and supplementary singularities such as joints and bridge approaches.All the issues above may harm road safety and the complexity of forensic investigations of pavements.Consequently,this study's objectives were confined to(1)carrying out friction measurements and analyzing the problem of friction decay over time;(2)setting up a method to lower the speed limits where friction decays are detected;(3)setting up a method to handle friction decays for autonomous vehicles.Results demonstrate that:(1)a power law describes how the speed limits are affected by friction;(2)for speeds up to 170 km/h,due to the lower reaction time,AV reaction distance is lower,which benefits AV traffic(lower stopping distance);(3)on the contrary,for higher values of friction and higher speeds,under the hypothesis of having the same reaction time law for non-AV(NAV)(i.e.,decreasing with the initial speed),AV speed limits become lower than NAV speed limits;(4)not only do comfort-based speed profiles for AVs bring higher braking distances,but also,in the median part(of the deceleration process),this could pose safety issues and reduce the distance between the available and the needed friction.展开更多
This study proposes a new component of the composite loss function minimised during training of the Super-Resolution(SR)algorithms—the normalised structural similarity index loss LSSIMN,which has the potential to imp...This study proposes a new component of the composite loss function minimised during training of the Super-Resolution(SR)algorithms—the normalised structural similarity index loss LSSIMN,which has the potential to improve the natural appearance of reconstructed images.Deep learning-based super-resolution(SR)algorithms reconstruct high-resolution images from low-resolution inputs,offering a practical means to enhance image quality without requiring superior imaging hardware,which is particularly important in medical applications where diagnostic accuracy is critical.Although recent SR methods employing convolutional and generative adversarial networks achieve high pixel fidelity,visual artefacts may persist,making the design of the loss function during training essential for ensuring reliable and naturalistic image reconstruction.Our research shows on two models—SR and Invertible Rescaling Neural Network(IRN)—trained on multiple benchmark datasets that the function LSSIMN significantly contributes to the visual quality,preserving the structural fidelity on the reference datasets.The quantitative analysis of results while incorporating LSSIMN shows that including this loss function component has a mean 2.88%impact on the improvement of the final structural similarity of the reconstructed images in the validation set,in comparison to leaving it out and 0.218%in comparison when this component is non-normalised.展开更多
Muscle Shortening Maneuver(MSM)is a rehabilitation technique successfully applied to several pathological conditions.The concept is to passively elongate and shorten the target muscle group of the affected limb.As a r...Muscle Shortening Maneuver(MSM)is a rehabilitation technique successfully applied to several pathological conditions.The concept is to passively elongate and shorten the target muscle group of the affected limb.As a result,the functionality(muscle strength and range of motion)of that limb is improved.The existing system induces these oscillations manually or without any feedback control,which can compromise the effectiveness and standardization of MSM.In this paper,we present a mechatronic system that can precisely deliver motion oscillations to the upper limb for a controllable execution of MSM.First,we collected the parameters(frequency and amplitude of the oscillations)from a system where a motor was heuristically used by a well-experienced therapist to induce the oscillations(without any feedback control).Based on these specifications,we chose the motor and rebuilt the experimental setup,implementing a sliding mode control with a sliding perturbation observer.With our system,the operator can choose a given frequency and amplitude of the oscillations within the range we experimentally observed.We tested our system with ten participants of different anthropometry.We found that our system can accurately reproduce oscillations in the frequency range 0.8 to 1.2 Hz and amplitude range 2 to 6 cm,with a maximum percentage normalized root mean square error around 7%.展开更多
1 Introduction Amid escalating global climate change,the“dual carbon”goals of carbon peak and carbon neutrality have become a focal point of global attention and an important strategy for sustainable development[1]....1 Introduction Amid escalating global climate change,the“dual carbon”goals of carbon peak and carbon neutrality have become a focal point of global attention and an important strategy for sustainable development[1].With the rapid development of renewable energy technologies and the increasing public demand for environmental protection and low-carbon living,the adoption of new energy vehicles,particularly electric vehicles(EVs).展开更多
Large-scale deep-seated landslides pose a significant threat to human life and infrastructure.Therefore,closely monitoring these landslides is crucial for assessing and mitigating their associated risks.In this paper,...Large-scale deep-seated landslides pose a significant threat to human life and infrastructure.Therefore,closely monitoring these landslides is crucial for assessing and mitigating their associated risks.In this paper,the authors introduce the So Lo Mon framework,a comprehensive monitoring system developed for three large-scale landslides in the Autonomous Province of Bolzano,Italy.A web-based platform integrates various monitoring data(GNSS,topographic data,in-place inclinometer),providing a user-friendly interface for visualizing and analyzing the collected data.This facilitates the identification of trends and patterns in landslide behaviour,enabling the triggering of warnings and the implementation of appropriate mitigation measures.The So Lo Mon platform has proven to be an invaluable tool for managing the risks associated with large-scale landslides through non-structural measures and driving countermeasure works design.It serves as a centralized data repository,offering visualization and analysis tools.This information empowers decisionmakers to make informed choices regarding risk mitigation,ultimately ensuring the safety of communities and infrastructures.展开更多
A class of stationary models of singular stochastic control has been studied, in which the state is extended to solution of a class of S.D.E. from Wiener process. The existence of optimal control has been proved in al...A class of stationary models of singular stochastic control has been studied, in which the state is extended to solution of a class of S.D.E. from Wiener process. The existence of optimal control has been proved in all cases under some weaker conditions, and the structure of optimal control may be characterized.展开更多
Internet of Things (IoT) has attracted extensive interest from both academia and industries, and is recognized as an ultimate infrastructure to connect everything at anytime and anywhere. The implementation of IoT gen...Internet of Things (IoT) has attracted extensive interest from both academia and industries, and is recognized as an ultimate infrastructure to connect everything at anytime and anywhere. The implementation of IoT generally faces the challenges from energy constraint and implementation cost. In this paper, we will introduce a new green communication paradigm, the ambient backscatter (AmBC), that could utilize the environmental wireless signals for both powering a tiny-cost device and backscattering the information symbols. Specifically, we will present the basic principles of AmBC, analyze its features and advantages, suggest its open problems, and predict its potential applications for our future IoT.展开更多
Oblique cutting is a working condition in fully mechanized mining whose function is making it possible for coal shearer to cut coal wall.Coal shearer often exhibit large vibration amplitudes in oblique cutting since t...Oblique cutting is a working condition in fully mechanized mining whose function is making it possible for coal shearer to cut coal wall.Coal shearer often exhibit large vibration amplitudes in oblique cutting since the shearer is forced to be bent.In this study,dynamic behavior in oblique cutting for the coal shearer cutting unit gearbox(SCUG)is investigated experimentally based on National Coal Mining Equipment Laboratory of China.A new long wall mining test set-up consists of a test coal shearer and other auxiliary machines is developed for operating long wall coal mining process.Realistic oblique cutting process is developed,and vibration response will be more accurate since both cutting loads and test machine in this experiment are realistic.A data-acquisition system consisting of sensors,channel conditioner and computer is developed to capture three-dimensional vibratory accelerations.A test matrix which included various combinations of key cutting load parameters is executed under realistic oblique cutting loads within a wide parameter range to establish database.Experimental data is analyzed in time,domain and time-frequency domains for investigating the rules of dynamic behavior for SCUG.Beat vibration phenomenon and the coupling of gear mesh frequencies are found in experiment,resulting in local resonance and reduce fatigue life of SCUG.The influence of cutting load on beat phenomenon and frequency coupling is demonstrated at the end,and some conclusions are obtained.展开更多
The stability of the periodic solution of the Duffing oscillator system in the periodic phase state is proved by using the Yoshizaw theorem, which establishes a theoretical basis for using this kind of chaotic oscilla...The stability of the periodic solution of the Duffing oscillator system in the periodic phase state is proved by using the Yoshizaw theorem, which establishes a theoretical basis for using this kind of chaotic oscillator system to detect weak signals. The restoring force term of the system affects the weak-signal detection ability of the system directly, the quantitative relationship between the coefficients of the linear and nonlinear items of the restoring force of the Duffing oscillator system and the SNR in the detection of weak signals is obtained through a large number of simulation experiments, then a new restoring force function with better detection results is established.展开更多
The 5th generation mobile communications aims at connecting everything and future Internet of Things(IoT)will get everything smartly connected.To realize it,there exist many challenges.One key challenge is the battery...The 5th generation mobile communications aims at connecting everything and future Internet of Things(IoT)will get everything smartly connected.To realize it,there exist many challenges.One key challenge is the battery problem for small devices,such as sensors or tags.Batteryless backscatter,also referred to as or battery-free backscatter,is a new potential technology to address this problem.One early and typical type of batteryless backscatter is ambient backscatter.Generally,batteryless backscatter utilizes environmental wireless signals to enable battery-free devices to communicate with each other.These devices first harvest energy from ambient wireless signals and then backscatter these signals so as to transmit their own information.This paper reviews the current studies about batteryless backscatter,including various backscatter schemes and theoretical works,and then introduces open problems for future research.展开更多
Thermo-poro-mechanical responses along sliding zone/surface have been extensively studied.However,it has not been recognized that the potential contribution of other crucial engineering geological interfaces beyond th...Thermo-poro-mechanical responses along sliding zone/surface have been extensively studied.However,it has not been recognized that the potential contribution of other crucial engineering geological interfaces beyond the slip surface to progressive failure.Here,we aim to investigate the subsurface multiphysics of reservoir landslides under two extreme hydrologic conditions(i.e.wet and dry),particularly within sliding masses.Based on ultra-weak fiber Bragg grating(UWFBG)technology,we employ specialpurpose fiber optic sensing cables that can be implanted into boreholes as“nerves of the Earth”to collect data on soil temperature,water content,pore water pressure,and strain.The Xinpu landslide in the middle reach of the Three Gorges Reservoir Area in China was selected as a case study to establish a paradigm for in situ thermo-hydro-poro-mechanical monitoring.These UWFBG-based sensing cables were vertically buried in a 31 m-deep borehole at the foot of the landslide,with a resolution of 1 m except for the pressure sensor.We reported field measurements covering the period 2021 and 2022 and produced the spatiotemporal profiles throughout the borehole.Results show that wet years are more likely to motivate landslide motions than dry years.The annual thermally active layer of the landslide has a critical depth of roughly 9 m and might move downward in warmer years.The dynamic groundwater table is located at depths of 9e15 m,where the peaked strain undergoes a periodical response of leap and withdrawal to annual hydrometeorological cycles.These interface behaviors may support the interpretation of the contribution of reservoir regulation to slope stability,allowing us to correlate them to local damage events and potential global destabilization.This paper also offers a natural framework for interpreting thermo-hydro-poro-mechanical signatures from creeping reservoir bank slopes,which may form the basis for a landslide monitoring and early warning system.展开更多
A new clustering algorithm called fuzzy self-organizing feature maps is introduced. It can process not only the exact digital inputs, but also the inexact or fuzzy non-digital inputs, such as natural language inputs. ...A new clustering algorithm called fuzzy self-organizing feature maps is introduced. It can process not only the exact digital inputs, but also the inexact or fuzzy non-digital inputs, such as natural language inputs. Simulation results show that the new algorithm is superior to original Kohonen’s algorithm in clustering performance and learning rate.展开更多
In this paper, we study the existence of least energy sign-changing solutions for aKirchhoff-type problem involving the fractional Laplacian operator. By using the constraintvariation method and quantitative deformati...In this paper, we study the existence of least energy sign-changing solutions for aKirchhoff-type problem involving the fractional Laplacian operator. By using the constraintvariation method and quantitative deformation lemma, we obtain a least energy nodal solu-tion ub for the given problem. Moreover, we show that the energy of ub is strictly larger thantwice the ground state energy. We also give a convergence property of ub as b O, where bis regarded as a positive parameter.展开更多
Train braking performance is important for the safety and reliability of railway systems. The availability of a tool that allows evaluating such performance on the basis of the main train features can be useful for tr...Train braking performance is important for the safety and reliability of railway systems. The availability of a tool that allows evaluating such performance on the basis of the main train features can be useful for train system designers to choose proper dimensions for and optimize train＇s subsystems. This paper presents a modular tool for the prediction of train braking performance, with a par- ticular attention to the accurate prediction of stopping distances. The tool takes into account different loading and operating conditions, in order to verify the safety require- ments prescribed by European technical specifications for interoperability of high-speed trains and the corresponding EN regulations. The numerical results given by the tool were verified and validated by comparison with experimental data, considering as benchmark case an Ansaldo EMU V250 train--a European high-speed train--currently developed for Belgium and Netherlands high-speed lines, on which technical information and experimental data directly recorded during the preliminary tests were available. An accurate identification of the influence of the braking pad friction factor on braking performances allowed obtaining reliable results.展开更多
Drive system is the key device of armored chassis. Its working state and reliability influence the maneuver performance of armored chassis directly. In order to simulate the failure process and evaluate the service re...Drive system is the key device of armored chassis. Its working state and reliability influence the maneuver performance of armored chassis directly. In order to simulate the failure process and evaluate the service reliability of drive system in training or battle missions,a new kind of dynamic simulation model and driving simulation platform of the complete drive system were established based on virtual prototype and finite element technology in this paper. Using the platform, the kinematics and dynamic characteristics of drive system were studied and analyzed in detail,the dynamic load spectrum of key components was obtained,the service life was predicted, and the service reliability evaluation results were provided. A simulation example of transmission gear was shown to illustrate the simulation and evaluation process. The result proves that the simulation method not only can be used to compute and evaluate the service reliability of complex mechanical mechanism, but also has high precision and reasonable computational cost. Therefore,simulation and reliability analysis based on virtual prototype of the armored chassis drive system will provide scientific reference for the formulation of armored chassis reasonable repair cycle.展开更多
In this study,deep-neural-network(DNN)-and artificial-neural-network(ANN)-based models along with regression models have been developed to estimate the pressure,bending and elongation values of ground-brick(GB)-added ...In this study,deep-neural-network(DNN)-and artificial-neural-network(ANN)-based models along with regression models have been developed to estimate the pressure,bending and elongation values of ground-brick(GB)-added mortar samples.This study is aimed at utilizing GB as a mineral additive in concrete in the ratios 0.0%,2.5%,5.0%,7.5%,10.0%,12.5%and 15.0%.In this study,756 mortar samples were produced for 84 different series and were cured in tap water(W),5%sodium sulphate solution(SS5)and 5%ammonium nitrate solution(AN5)for 7 days,28 days,90 days and 180 days.The developed DNN models have three inputs and two hidden layers with 20 neurons and one output,whereas the ANN models have three inputs,one output and one hidden layer with 15 neurons.Twenty-five previously obtained experimental sample datasets were used to train these developed models and to generate the regression equation.Fifty-nine non-training-attributed datasets were used to test the models.When these test values were attributed to the trained DNN,ANN and regression models,the brick-dust pressure as well as the bending and elongation values have been observed to be very close to the experimental values.Although only a small fraction(30%)of the experimental data were used for training,both the models performed the estimation process at a level that was in accordance with the opinions of experts.The fact that this success has been achieved using very little training data shows that the models have been appropriately designed.In addition,the DNN models exhibited better performance as compared with that exhibited by the ANN models.The regression model is a model whose performance is worst and unacceptable;further,the prediction error is observed to be considerably high.In conclusion,ANN-and DNN-based models are practical and effective to estimate these values.展开更多
We propose a novel refractive index sensor based on Michelson interferometer by using double-core microfiber.Through the reflection of the end and taper of double-core fiber(DCF),the Michelson interference spectrum is...We propose a novel refractive index sensor based on Michelson interferometer by using double-core microfiber.Through the reflection of the end and taper of double-core fiber(DCF),the Michelson interference spectrum is formed.Owing to the structure characteristic of double-core microfiber,this interferometer can achieve the measurement of refractive index(RI)and temperature.The experimental results show that the refractive index sensitivity of the interferometer is 2377.80 nm/RIU at the diameter of the taper waist of 8.76μm.In the temperature ranges from 30°C to 60°C,the temperature sensitivity is 0.07048 nm/°C.This sensor has the advantage of high refractive index sensitivity.展开更多
基金National Natural Science Foundation of China(No.61271152)Natural Science Foundation of Hebei Province,China(No.F2012506008)the Original Innovation Foundation of Ordnance Engineering College,China(No.YSCX0903)
文摘Considering the secure authentication problem for equipment support information network,a clustering method based on the business information flow is proposed. Based on the proposed method,a cluster-based distributed authentication mechanism and an optimal design method for distributed certificate authority( CA)are designed. Compared with some conventional clustering methods for network,the proposed clustering method considers the business information flow of the network and the task of the network nodes,which can decrease the communication spending between the clusters and improve the network efficiency effectively. The identity authentication protocols between the nodes in the same cluster and in different clusters are designed. From the perspective of the security of network and the availability of distributed authentication service,the definition of the secure service success rate of distributed CA is given and it is taken as the aim of the optimal design for distributed CA. The efficiency of providing the distributed certificate service successfully by the distributed CA is taken as the constraint condition of the optimal design for distributed CA. The determination method for the optimal value of the threshold is investigated. The proposed method can provide references for the optimal design for distributed CA.
基金supported by National Natural Science Foundation of China (NSFC) (No. U2001216)Shenzhen Science and Technology Innovation Committee (No. 20231121102401001)the Shenzhen Key Laboratory Project (No. ZDSYS201602261933302)。
文摘Integrated perovskite-organic solar cells(IPOSCs) offer a promising hybrid approach that combines the advantages of perovskite and organic solar cells, enabling efficient photon absorption across a broad spectrum with a simplified architecture. However, challenges such as limited charge mobility in organic bulk heterojunction(BHJ) layers, and energy-level mismatch at the perovskite/BHJ interface still sustain. Recent advancements in non-fullerene acceptors(NFAs), interfacial engineering, and emerging materials have improved charge transfer/transport, and overall power conversion efficiency(PCE) of IPOSCs.This review explores key developments in IPOSCs, focusing on low-bandgap materials for near-infrared absorption, energy alignment optimization, and strategies to enhance photocurrent density and device performance. Future innovations in material selection and device architecture will be crucial for further improving the efficiency of IPOSCs, bringing them closer to practical application in next-generation photovoltaic technologies.
文摘Commonly,the standards for the geometric design of roads refer to a given set of values for the friction coefficient(longitudinal and transverse friction).These"reference"values imply corresponding visibility sights,curvature radii,and speed limits.Unfortunately,not only do these reference values not correspond to a given standard to measure them,but nothing is said about the decrease of the posted speed limit(variable speed limits)when roads become slippery and lanes for autonomous vehicle(AV)are concerned.Furthermore,the same assessment of the friction coefficient has plenty of uncertainties due to measurement device,temperature,location,time passed from the construction,alignment-related variables(e.g.,curve,tangent,transition curve,convexity/crests or concavity/sags,longitudinal slope,superelevation,and ruling gradient),and supplementary singularities such as joints and bridge approaches.All the issues above may harm road safety and the complexity of forensic investigations of pavements.Consequently,this study's objectives were confined to(1)carrying out friction measurements and analyzing the problem of friction decay over time;(2)setting up a method to lower the speed limits where friction decays are detected;(3)setting up a method to handle friction decays for autonomous vehicles.Results demonstrate that:(1)a power law describes how the speed limits are affected by friction;(2)for speeds up to 170 km/h,due to the lower reaction time,AV reaction distance is lower,which benefits AV traffic(lower stopping distance);(3)on the contrary,for higher values of friction and higher speeds,under the hypothesis of having the same reaction time law for non-AV(NAV)(i.e.,decreasing with the initial speed),AV speed limits become lower than NAV speed limits;(4)not only do comfort-based speed profiles for AVs bring higher braking distances,but also,in the median part(of the deceleration process),this could pose safety issues and reduce the distance between the available and the needed friction.
基金support from the following institutional grant.Internal Grant Agency of the Faculty of Economics and Management,Czech University of Life Sciences Prague,grant no.2023A0004(https://iga.pef.czu.cz/,accessed on 6 June 2025).
文摘This study proposes a new component of the composite loss function minimised during training of the Super-Resolution(SR)algorithms—the normalised structural similarity index loss LSSIMN,which has the potential to improve the natural appearance of reconstructed images.Deep learning-based super-resolution(SR)algorithms reconstruct high-resolution images from low-resolution inputs,offering a practical means to enhance image quality without requiring superior imaging hardware,which is particularly important in medical applications where diagnostic accuracy is critical.Although recent SR methods employing convolutional and generative adversarial networks achieve high pixel fidelity,visual artefacts may persist,making the design of the loss function during training essential for ensuring reliable and naturalistic image reconstruction.Our research shows on two models—SR and Invertible Rescaling Neural Network(IRN)—trained on multiple benchmark datasets that the function LSSIMN significantly contributes to the visual quality,preserving the structural fidelity on the reference datasets.The quantitative analysis of results while incorporating LSSIMN shows that including this loss function component has a mean 2.88%impact on the improvement of the final structural similarity of the reconstructed images in the validation set,in comparison to leaving it out and 0.218%in comparison when this component is non-normalised.
基金supported by the European Union by the Next Generation EU Project ECS00000017‘Ecosistema dell’Innovazione’Tuscany Health Ecosystem(THE,PNRR,Spoke 9:Robotics and Automation for Health)by the Italian Ministry of Education and Research(MUR)in the framework of the FoReLab project(Departments of Excellence).
文摘Muscle Shortening Maneuver(MSM)is a rehabilitation technique successfully applied to several pathological conditions.The concept is to passively elongate and shorten the target muscle group of the affected limb.As a result,the functionality(muscle strength and range of motion)of that limb is improved.The existing system induces these oscillations manually or without any feedback control,which can compromise the effectiveness and standardization of MSM.In this paper,we present a mechatronic system that can precisely deliver motion oscillations to the upper limb for a controllable execution of MSM.First,we collected the parameters(frequency and amplitude of the oscillations)from a system where a motor was heuristically used by a well-experienced therapist to induce the oscillations(without any feedback control).Based on these specifications,we chose the motor and rebuilt the experimental setup,implementing a sliding mode control with a sliding perturbation observer.With our system,the operator can choose a given frequency and amplitude of the oscillations within the range we experimentally observed.We tested our system with ten participants of different anthropometry.We found that our system can accurately reproduce oscillations in the frequency range 0.8 to 1.2 Hz and amplitude range 2 to 6 cm,with a maximum percentage normalized root mean square error around 7%.
基金supported by Yunnan Provincial Basic Research Project(202401AT070344)National Natural Science Foundation of China(62263014).
文摘1 Introduction Amid escalating global climate change,the“dual carbon”goals of carbon peak and carbon neutrality have become a focal point of global attention and an important strategy for sustainable development[1].With the rapid development of renewable energy technologies and the increasing public demand for environmental protection and low-carbon living,the adoption of new energy vehicles,particularly electric vehicles(EVs).
基金funded by the So Lo Mon project“Monitoraggio a Lungo Termine di Grandi Frane basato su Sistemi Integrati di Sensori e Reti”(Longterm monitoring of large-scale landslides based on integrated systems of sensors and networks),Program EFRE-FESR 2014–2020,Project EFRE-FESR4008 South Tyrol–Person in charge:V.Mair。
文摘Large-scale deep-seated landslides pose a significant threat to human life and infrastructure.Therefore,closely monitoring these landslides is crucial for assessing and mitigating their associated risks.In this paper,the authors introduce the So Lo Mon framework,a comprehensive monitoring system developed for three large-scale landslides in the Autonomous Province of Bolzano,Italy.A web-based platform integrates various monitoring data(GNSS,topographic data,in-place inclinometer),providing a user-friendly interface for visualizing and analyzing the collected data.This facilitates the identification of trends and patterns in landslide behaviour,enabling the triggering of warnings and the implementation of appropriate mitigation measures.The So Lo Mon platform has proven to be an invaluable tool for managing the risks associated with large-scale landslides through non-structural measures and driving countermeasure works design.It serves as a centralized data repository,offering visualization and analysis tools.This information empowers decisionmakers to make informed choices regarding risk mitigation,ultimately ensuring the safety of communities and infrastructures.
基金Supported by the National Science Foundation of China.
文摘A class of stationary models of singular stochastic control has been studied, in which the state is extended to solution of a class of S.D.E. from Wiener process. The existence of optimal control has been proved in all cases under some weaker conditions, and the structure of optimal control may be characterized.
基金supported in part by National Key R&D Program of China under Grant 2016YFE0200900part by Scientific Research Program of Beijing Municipal Commission of Education under Grant KM201910853003part by Major projects of Beijing Municipal Science and Technology Commission under Grant Z181100003218010
文摘Internet of Things (IoT) has attracted extensive interest from both academia and industries, and is recognized as an ultimate infrastructure to connect everything at anytime and anywhere. The implementation of IoT generally faces the challenges from energy constraint and implementation cost. In this paper, we will introduce a new green communication paradigm, the ambient backscatter (AmBC), that could utilize the environmental wireless signals for both powering a tiny-cost device and backscattering the information symbols. Specifically, we will present the basic principles of AmBC, analyze its features and advantages, suggest its open problems, and predict its potential applications for our future IoT.
基金This paper was supported by the National Basic Research Program of China(2014CB046303).
文摘Oblique cutting is a working condition in fully mechanized mining whose function is making it possible for coal shearer to cut coal wall.Coal shearer often exhibit large vibration amplitudes in oblique cutting since the shearer is forced to be bent.In this study,dynamic behavior in oblique cutting for the coal shearer cutting unit gearbox(SCUG)is investigated experimentally based on National Coal Mining Equipment Laboratory of China.A new long wall mining test set-up consists of a test coal shearer and other auxiliary machines is developed for operating long wall coal mining process.Realistic oblique cutting process is developed,and vibration response will be more accurate since both cutting loads and test machine in this experiment are realistic.A data-acquisition system consisting of sensors,channel conditioner and computer is developed to capture three-dimensional vibratory accelerations.A test matrix which included various combinations of key cutting load parameters is executed under realistic oblique cutting loads within a wide parameter range to establish database.Experimental data is analyzed in time,domain and time-frequency domains for investigating the rules of dynamic behavior for SCUG.Beat vibration phenomenon and the coupling of gear mesh frequencies are found in experiment,resulting in local resonance and reduce fatigue life of SCUG.The influence of cutting load on beat phenomenon and frequency coupling is demonstrated at the end,and some conclusions are obtained.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 40374045 and 40574051）, and by the Jilin Technology Development Plan （Grant No 20050526）,
文摘The stability of the periodic solution of the Duffing oscillator system in the periodic phase state is proved by using the Yoshizaw theorem, which establishes a theoretical basis for using this kind of chaotic oscillator system to detect weak signals. The restoring force term of the system affects the weak-signal detection ability of the system directly, the quantitative relationship between the coefficients of the linear and nonlinear items of the restoring force of the Duffing oscillator system and the SNR in the detection of weak signals is obtained through a large number of simulation experiments, then a new restoring force function with better detection results is established.
基金This paper is funded by Scientific Research Program of Beijing Municipal Commission of Education No.KM201910853003.
文摘The 5th generation mobile communications aims at connecting everything and future Internet of Things(IoT)will get everything smartly connected.To realize it,there exist many challenges.One key challenge is the battery problem for small devices,such as sensors or tags.Batteryless backscatter,also referred to as or battery-free backscatter,is a new potential technology to address this problem.One early and typical type of batteryless backscatter is ambient backscatter.Generally,batteryless backscatter utilizes environmental wireless signals to enable battery-free devices to communicate with each other.These devices first harvest energy from ambient wireless signals and then backscatter these signals so as to transmit their own information.This paper reviews the current studies about batteryless backscatter,including various backscatter schemes and theoretical works,and then introduces open problems for future research.
基金We acknowledge the funding support from the National Science Fund for Distinguished Young Scholars of National Natural Science Foundation of China(Grant No.42225702)the National Natural Science Foundation of China(Grant No.42077235).
文摘Thermo-poro-mechanical responses along sliding zone/surface have been extensively studied.However,it has not been recognized that the potential contribution of other crucial engineering geological interfaces beyond the slip surface to progressive failure.Here,we aim to investigate the subsurface multiphysics of reservoir landslides under two extreme hydrologic conditions(i.e.wet and dry),particularly within sliding masses.Based on ultra-weak fiber Bragg grating(UWFBG)technology,we employ specialpurpose fiber optic sensing cables that can be implanted into boreholes as“nerves of the Earth”to collect data on soil temperature,water content,pore water pressure,and strain.The Xinpu landslide in the middle reach of the Three Gorges Reservoir Area in China was selected as a case study to establish a paradigm for in situ thermo-hydro-poro-mechanical monitoring.These UWFBG-based sensing cables were vertically buried in a 31 m-deep borehole at the foot of the landslide,with a resolution of 1 m except for the pressure sensor.We reported field measurements covering the period 2021 and 2022 and produced the spatiotemporal profiles throughout the borehole.Results show that wet years are more likely to motivate landslide motions than dry years.The annual thermally active layer of the landslide has a critical depth of roughly 9 m and might move downward in warmer years.The dynamic groundwater table is located at depths of 9e15 m,where the peaked strain undergoes a periodical response of leap and withdrawal to annual hydrometeorological cycles.These interface behaviors may support the interpretation of the contribution of reservoir regulation to slope stability,allowing us to correlate them to local damage events and potential global destabilization.This paper also offers a natural framework for interpreting thermo-hydro-poro-mechanical signatures from creeping reservoir bank slopes,which may form the basis for a landslide monitoring and early warning system.
文摘A new clustering algorithm called fuzzy self-organizing feature maps is introduced. It can process not only the exact digital inputs, but also the inexact or fuzzy non-digital inputs, such as natural language inputs. Simulation results show that the new algorithm is superior to original Kohonen’s algorithm in clustering performance and learning rate.
基金supported by the NSFC(11501231)the "Fundamental Research Funds for the Central Universities"(WUT2017IVA077,2018IB014)
文摘In this paper, we study the existence of least energy sign-changing solutions for aKirchhoff-type problem involving the fractional Laplacian operator. By using the constraintvariation method and quantitative deformation lemma, we obtain a least energy nodal solu-tion ub for the given problem. Moreover, we show that the energy of ub is strictly larger thantwice the ground state energy. We also give a convergence property of ub as b O, where bis regarded as a positive parameter.
文摘Train braking performance is important for the safety and reliability of railway systems. The availability of a tool that allows evaluating such performance on the basis of the main train features can be useful for train system designers to choose proper dimensions for and optimize train＇s subsystems. This paper presents a modular tool for the prediction of train braking performance, with a par- ticular attention to the accurate prediction of stopping distances. The tool takes into account different loading and operating conditions, in order to verify the safety require- ments prescribed by European technical specifications for interoperability of high-speed trains and the corresponding EN regulations. The numerical results given by the tool were verified and validated by comparison with experimental data, considering as benchmark case an Ansaldo EMU V250 train--a European high-speed train--currently developed for Belgium and Netherlands high-speed lines, on which technical information and experimental data directly recorded during the preliminary tests were available. An accurate identification of the influence of the braking pad friction factor on braking performances allowed obtaining reliable results.
文摘Drive system is the key device of armored chassis. Its working state and reliability influence the maneuver performance of armored chassis directly. In order to simulate the failure process and evaluate the service reliability of drive system in training or battle missions,a new kind of dynamic simulation model and driving simulation platform of the complete drive system were established based on virtual prototype and finite element technology in this paper. Using the platform, the kinematics and dynamic characteristics of drive system were studied and analyzed in detail,the dynamic load spectrum of key components was obtained,the service life was predicted, and the service reliability evaluation results were provided. A simulation example of transmission gear was shown to illustrate the simulation and evaluation process. The result proves that the simulation method not only can be used to compute and evaluate the service reliability of complex mechanical mechanism, but also has high precision and reasonable computational cost. Therefore,simulation and reliability analysis based on virtual prototype of the armored chassis drive system will provide scientific reference for the formulation of armored chassis reasonable repair cycle.
文摘In this study,deep-neural-network(DNN)-and artificial-neural-network(ANN)-based models along with regression models have been developed to estimate the pressure,bending and elongation values of ground-brick(GB)-added mortar samples.This study is aimed at utilizing GB as a mineral additive in concrete in the ratios 0.0%,2.5%,5.0%,7.5%,10.0%,12.5%and 15.0%.In this study,756 mortar samples were produced for 84 different series and were cured in tap water(W),5%sodium sulphate solution(SS5)and 5%ammonium nitrate solution(AN5)for 7 days,28 days,90 days and 180 days.The developed DNN models have three inputs and two hidden layers with 20 neurons and one output,whereas the ANN models have three inputs,one output and one hidden layer with 15 neurons.Twenty-five previously obtained experimental sample datasets were used to train these developed models and to generate the regression equation.Fifty-nine non-training-attributed datasets were used to test the models.When these test values were attributed to the trained DNN,ANN and regression models,the brick-dust pressure as well as the bending and elongation values have been observed to be very close to the experimental values.Although only a small fraction(30%)of the experimental data were used for training,both the models performed the estimation process at a level that was in accordance with the opinions of experts.The fact that this success has been achieved using very little training data shows that the models have been appropriately designed.In addition,the DNN models exhibited better performance as compared with that exhibited by the ANN models.The regression model is a model whose performance is worst and unacceptable;further,the prediction error is observed to be considerably high.In conclusion,ANN-and DNN-based models are practical and effective to estimate these values.
基金supported by the National Natural Science Foundation of China(No.61735011)the Science and Technology Research Project of Hebei University(No.QN2017141)the Key Research and Development Program of Hebei Province(No.19251703D)。
文摘We propose a novel refractive index sensor based on Michelson interferometer by using double-core microfiber.Through the reflection of the end and taper of double-core fiber(DCF),the Michelson interference spectrum is formed.Owing to the structure characteristic of double-core microfiber,this interferometer can achieve the measurement of refractive index(RI)and temperature.The experimental results show that the refractive index sensitivity of the interferometer is 2377.80 nm/RIU at the diameter of the taper waist of 8.76μm.In the temperature ranges from 30°C to 60°C,the temperature sensitivity is 0.07048 nm/°C.This sensor has the advantage of high refractive index sensitivity.
