This paper addresses the verification of strong currentstate opacity with respect to real-time observations generated from a discrete-event system that is modeled with time labeled Petri nets. The standard current-sta...
详细信息
This paper addresses the verification of strong currentstate opacity with respect to real-time observations generated from a discrete-event system that is modeled with time labeled Petri nets. The standard current-state opacity cannot completely characterize higher-level security. To ensure the higher-level security requirements of a time-dependent system, we propose a strong version of opacity known as strong current-state opacity. For any path(state-event sequence with time information)π derived from a real-time observation that ends at a secret state, the strong current-state opacity of the real-time observation signifies that there is a non-secret path with the same real-time observation as π. We propose general and non-secret state class graphs, which characterize the general and non-secret states of time-dependent systems, respectively. To capture the observable behavior of non-secret states, a non-secret observer is ***, we develop a structure called a real-time concurrent verifier to verify the strong current-state opacity of time labeled Petri nets. This approach is efficient since the real-time concurrent verifier can be constructed by solving a certain number of linear programming problems.
Considering the fracture problem of the silica-based ceramic core in the integrated casting of hollow turbine blades during directional solidification,the influence of various whiskers,including silicon carbide whiske...
详细信息
Considering the fracture problem of the silica-based ceramic core in the integrated casting of hollow turbine blades during directional solidification,the influence of various whiskers,including silicon carbide whiskers,silicon nitride whiskers,and mullite whiskers,on the high-temperature strength of the silica-based ceramic core was ***,the formation of microstructure morphology and phase structure was *** results show that silicon carbide whiskers can reduce the microcracks caused by the shrinkage of *** the sintering process,some of the silicon carbide whiskers oxidize and react with aluminum powder to form mullite,which can improve the high-temperature strength of the ceramic *** the content of silicon carbide whiskers is 3wt.%,the high-temperature bending strength of the cores reaches the maximum value of 21 *** nitride whiskers decompose in a high-temperature environment and react with aluminum powder in the matrix material to form mullite *** the content of silicon nitride whiskers is 5wt.%,the high-temperature bending strength of the cores reaches 20 *** adding mullite whiskers,a structure of cristobalite wrapped mullite whiskers can be formed to achieve *** the content of mullite whiskers is 4wt.%,the high-temperature bending strength can reach 17.2 *** comparing the performance of silicon carbide whiskers,silicon nitride whiskers,and mullite whiskers,along with conducting slurry viscosity tests and casting experiments,it is determined that a ceramic slurry containing 4wt.%mullite whiskers is the most suitable for making the cores used in the integrated casting of hollow turbine blades.
Investigations on the fabrication of large-size lightweight Mg alloy components by wire-arc directed en-ergy deposition(DED)are steadily ***,most of these components still suffer from inferior performance due to inter...
详细信息
Investigations on the fabrication of large-size lightweight Mg alloy components by wire-arc directed en-ergy deposition(DED)are steadily ***,most of these components still suffer from inferior performance due to internal defects and inherent columnar ***,external ultrasound fields with different powers were successfully introduced into the wire-arc DED of AZ31 Mg *** microstructure,defects,and mechanical properties of the fabricated components were carefully charac-terized and *** results show that the external ultrasound fields lead to decreased porosity,complete columnar to equiaxed transition(CET),and enhanced ***,the UA90 samples exhibited a remarkable increase of~30%,~45%,and~189%in yield strength,ultimate tensile strength,and elongation,*** dominant mechanisms of enhanced strength-ductility synergy were analyzed in *** study thus sheds new light on wire-arc DED of Mg alloy components with excellent performance via external ultrasound fields.
Image-based micromechanical models,necessary for the development of structure-property-response relations,are far from mature for complex microstructures with multi-modal distributions of morphological and crystallogr...
详细信息
Image-based micromechanical models,necessary for the development of structure-property-response relations,are far from mature for complex microstructures with multi-modal distributions of morphological and crystallographic features,such as those occurring with cold spray-formed(CSF)aluminum *** materials have a bimodal polycrystalline microstructure composed of recrystallized ultra-fine grains(UFGs)and deformed coarse grains(CGs)within prior particles.A prime reason is the lack of robust approaches for generating statistically equivalent virtual microstructures(SEVM)capturing the statistics of characteristic morphological and crystallographic features,such as grain size,crystallographic orientations,and *** paper introduces an approach,strategically integrating Generative Adversarial Network-based approaches for producing bimodal CSF AA7050 alloy microstructures,with the synthetic microstructure builder Dream3D for packing prior particles with CGs having statistically equivalent morphological and crystallographic descriptors to electron backscatter diffraction(EBSD)*** efficient finite element(FE)simulation approach is developed for the SEVMs to generate local and overall response functions through the creation of sub-volume elements(SVEs).
In this study, we develop and investigate a control algorithm for wheeled quadruped robots, taking advantage of the combined benefits of legs and wheels. Robots with legs exhibit excellent maneuverability across vario...
详细信息
MEMS/NEMS resonant sensors hold promise for minute mass and force ***,one major challenge is that conventional externally driven sensors inevitably encounter undesired intrinsic noise,which imposes a fundamental limit...
详细信息
MEMS/NEMS resonant sensors hold promise for minute mass and force ***,one major challenge is that conventional externally driven sensors inevitably encounter undesired intrinsic noise,which imposes a fundamental limitation upon their signal-to-noise ratio(SNR)and,consequently,the ***,this restriction becomes increasingly pronounced as sensors shrink to the *** this work,we propose a counterintuitive paradigm shift that turns intrinsic thermal noise from an impediment to a constituent of the sensor by harvesting it as the driving force,obviating the need for external actuation and realizing‘noise-driven’*** sensors employ the dynamically amplified response to thermal noise at resonances for stimulus *** demonstrate that lightly damped and highly compliant nano-structures with high aspect ratios are promising candidates for this class of *** overcome the phase incoherence of the drive force,three noise-enabled quantitative sensing mechanisms are *** validated our sensor paradigm by experimental demonstrating noise-driven pressure and temperature ***-driven sensors offer a new opportunity for delivering practical NEMS sensors that can function at room temperature and under ambient pressure,and a development that suggests a path to cheaper,simpler,and low-power-consumption sensors.
Urban air mobility (UAM) refers to an aviation transportation system that utilizes vertical take-off and landing (VTOL) aircraft for the safe and convenient transportation of passengers and cargos. VTOL aircraft can b...
详细信息
The regularization theory has successfully enabled the removal of gravitational singularities associated with celestial *** this study,regularizing techniques are merged into a multi-impulse trajectory design framewor...
详细信息
The regularization theory has successfully enabled the removal of gravitational singularities associated with celestial *** this study,regularizing techniques are merged into a multi-impulse trajectory design framework that requires delicate computations,particularly for a fuel minimization *** variables based on the Levi–Civita or Kustaanheimo–Stiefel transformations express instantaneous velocity changes in a gradient-based direct optimization *** formulation removes the adverse singularities associated with the null thrust impulses from the derivatives of an objective function in the fuel minimization *** favorite singularity-free property enables the accurate reduction of unnecessary impulses and the generation of necessary impulses for local optimal solutions in an automatic *** of fuel-optimal multi-impulse trajectories are presented,including novel transfer solutions between a near-rectilinear halo orbit and a distant retrograde orbit.
Prognostics and health management(PHM)has gotten considerable attention in the background of Industry *** PHM contributes to the reliable and safe operation of electric ***,relevant reviews are still continuously upda...
详细信息
Prognostics and health management(PHM)has gotten considerable attention in the background of Industry *** PHM contributes to the reliable and safe operation of electric ***,relevant reviews are still continuously updated over *** this paper,we browsed extensive literature related to battery PHM from 2018to 2023 and summarized advances in battery PHM field,including battery testing and public datasets,fault diagnosis and prediction methods,health status estimation and health management *** last topic includes state of health estimation methods,remaining useful life prediction methods and predictive maintenance *** of these categories is introduced and discussed in *** on this survey,we accordingly discuss challenges left to battery PHM,and provide future research *** research systematically reviews recent research about battery PHM from the perspective of key PHM steps and provide some valuable prospects for researchers and practitioners.
In current research,many researchers propose analytical expressions for calculating the packing structure of spherical particles such as DN Model,Compact Model and NLS criterion et ***,there is still a question that h...
详细信息
In current research,many researchers propose analytical expressions for calculating the packing structure of spherical particles such as DN Model,Compact Model and NLS criterion et ***,there is still a question that has not been well explained *** is:What is the core factors affecting the thermal conductivity of particles?In this paper,based on the coupled discrete element-finite difference(DE-FD)method and spherical aluminum powder,the relationship between the parameters and the thermal conductivity of the powder(ETC_(p))is *** is found that the key factor that can described the change trend of ETC_(p) more accurately is not the materials of the powder but the average contact area between particles(a_(ave))which also have a close nonlinear relationship with the average particle size d_(50).Based on this results,the expression for calculating the ETC_(p) of the sphere metal powder is successfully reduced to only one main parameter d_(50)and an efficient calculation model is proposed which can applicate both in room and high temperature and the corresponding error is less than 20.9%in room ***,in this study,based on the core factors analyzation,a fast calculation model of ETC_(p) is proposed,which has a certain guiding significance in the field of thermal field simulation.
暂无评论