This paper considers the stabilization of the coupled wave systems with spatially-varying *** authors design a state feedback controller by backstepping *** contrast to the previous work in the literature,the kernel e...
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This paper considers the stabilization of the coupled wave systems with spatially-varying *** authors design a state feedback controller by backstepping *** contrast to the previous work in the literature,the kernel equations become more complicated and the main difficulty lies in proving the existence and uniqueness of the solution to the kernel ***,using the backstepping approach,the authors verify the kernel equations,which is a system of coupled hyperbolic equations with spatially-varying ***,the existence and uniqueness of the kernel matrices is ***,the authors use a Lyapunov function to get the exponential stabilization of the closed-loop system.A numerical example is presented to illustrate the effectiveness of the proposed controller.
Active control of aero-engine turbine tip clearance is one of the best chances for engine performance uplift *** do that,the first requirement is real-time measurement of tip clearance in aero-engine working ***,turbi...
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Active control of aero-engine turbine tip clearance is one of the best chances for engine performance uplift *** do that,the first requirement is real-time measurement of tip clearance in aero-engine working ***,turbine complexity makes it unlikely for tip clearance sensors to be *** recognition of that,this paper proposed a model-based method for tip clearance ***,by considering previously wrongly neglected factors such as load deformation,a mathematical model to monitor dynamic tip clearance changes is built to improve calculation ***,after clarifying the coupling relationship between engine models and tip clearance models,this paper builds a component-level mathematical model integrating dynamic characteristics of turbine tip clearance,which helps realize accurate measurement of tip clearance in working *** tip clearance affects turbine efficiency is studied afterwards and reported to aero-engine model,so as to mitigate performance difference between aero-engine model and real engines caused by turbine tip ***,by hardware-in-the-loop simulation,tip clearance model demonstrates 15.9%better accuracy than previously built models in terms of turbine centrifugal deformation *** tip clearance measurement model takes averagely 0.34 ms in calculation,meeting the operation requirement,it proves to be an effective new way.
Quantum-confined CsPbBr_(3) perovskites are promising blue emitters for ultra-high-definition displays,but their soft lattice caused by highly ionic nature has a limited ***,we endow CsPbBr_(3) nanoplatelets(NPLs)with...
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Quantum-confined CsPbBr_(3) perovskites are promising blue emitters for ultra-high-definition displays,but their soft lattice caused by highly ionic nature has a limited ***,we endow CsPbBr_(3) nanoplatelets(NPLs)with atomic crystal-like structural rigidity through proper surface engineering,by using strongly bound N-dodecylbenzene sulfonic acid(DBSA).A stable,rigid crystal structure,as well as uniform,orderly-arranged surface of these NPLs is achieved by optimizing intermediate reaction stage,by switching from molecular clusters to mono-octahedra,while interaction with DBSA resulted in formation of a Cs_(x)O monolayer shell capping the NPL *** a result,both structural and optical stability of the CsPbBr3 NPLs is enhanced by strong covalent bonding of DBSA,which inhibits undesired phase transitions and decomposition of the perovskite phase potentially caused by ligand ***,rather small amount of DBSA ligands at the NPL surface results in a short inter-NPL spacing in their closely-packed films,which facilitates efficient charge injection and *** photoluminescence of the produced CsPbBr_(3) NPLs is bright(nearly unity emission quantum yield)and peaks at 457 nm with an extremely narrow bandwidth of 3.7 nm at 80 K,while the bandwidth of the electroluminescence(peaked at 460 nm)also reaches a record-narrow value of 15 nm at room *** value corresponds to the CIE coordinates of(0.141,0.062),which meets Rec.2020 standards for ultra-high-definition displays.
High-performance servo joints are the basis for quadruped robots to have excellent motion performance. The current loop is the innermost loop of the servo system, and its control effect on torque directly determines t...
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The wheel-rail wear was predicted for modern trams with independently rotating wheelset running on a groove-shaped rail. The tram vehicle-track coupled dynamics model, considering the wheel-rail multi-point contact, w...
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The development of automatic driving, unmanned aerial vehicle detection and virtual reality cannot be separated from the research of 3D point cloud. Existing studies either lack of local shape capture and local spatia...
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Micro-cylindrical temperature sensors are crucial components for in-situ physiological signal monitoring in smart healthcare and minimally invasive surgical ***,due to the high-curvature complexity of the substrates,h...
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Micro-cylindrical temperature sensors are crucial components for in-situ physiological signal monitoring in smart healthcare and minimally invasive surgical ***,due to the high-curvature complexity of the substrates,highprecision microfabrication on micro-cylindrical surfaces still faces significant *** study proposes a microcylindrical electrohydrodynamic printing process to achieve on-demand high-resolution patterning on high-curvature surfaces with diameters ranging from 55μm to 10 mm,addressing issues of mapping errors and stress concentration in array sensors integrated on micro-cylindrical surfaces.A physical model of micro-cylindrical electrohydrodynamic printing is established based on two-phase flow electrohydrodynamics to analyze the factors affecting the formation of stable cone-jets and the deposition of ink droplets on curved *** the elongated and high-curvature characteristics of micro-cylindrical objects,a printing system is designed with four degrees of freedom,coupling object rotation and *** simulations reveal the patterns of electric field distortion caused by the horizontal offset of the nozzle relative to the vertical symmetry axis of the object,while experimental results identify the printing windows for inks of varying viscosities,voltages,and printing ***,a temperature sensor array is fabricated on the micro-cylindrical surface(sensor line width~150μm,lead wire width less than 50μm,sensitivity~0.00106),validating the consistency and stability of the array sensors and enabling temperature measurements in the range of 20℃‒100℃.Additionally,the capability of the sensors array for temperature monitoring in simulated narrow cavity heating environments is demonstrated,exploring a novel method for fabricating advanced minimally invasive surgical instruments.
First, this paper proposes that although the small hydropower group in the basin terrace as a whole uses the hydrological natural flow to generate electricity, the small hydropower except the first stage will also reu...
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First, this paper proposes that although the small hydropower group in the basin terrace as a whole uses the hydrological natural flow to generate electricity, the small hydropower except the first stage will also reuse a certain proportion of the small hydropower outflow and immediately upper stage, solving the problem of the relationship between the total power prediction of the small hydropower group and the hydrological natural flow prediction at all levels. Second, this paper proposes a satellite remote sensing monitoring point selection method based on topographic elevation to determine the increment of rainfall collection area above each small hydropower dam site, solving the correspondence between the source of the incoming flow of each small hydropower and the rainfall collection area above the dam site nested step by step, and the problem that each small hydropower is dividing the hydrological and natural flow of the whole basin according to the increment of rainfall collection area above the dam site. Third, this paper proposes a method that combines computational yield flow, deep learning simulation of sink flow, and fitting small hydropower generation equations, i.e., considering the distributed yield flow TCN-LSTM model (DR-TCN-LSTM), which solves the problem that the major part of the incoming flow except for the first level small hydropower is the reuse of the outgoing flow and the immediate upper-level small hydropower, which is treated by the immediate upper-level small hydropower, rather than the purely natural state product of the problem. In an example of an 8-step prediction of multiple small hydropower stations' total power in a certain basin in Guangxi, China within a day, this paper proposes a Distributed Runoff TCN-LSTM Model (DR-BP-LSTM), and the Nash coefficient of the total power is 0.919. The Nash coefficient is increased by 0.02 due to the calculated discharge. In the selection of deep learning models, the Nash coefficient of the predi
Avatars, as promising digital representations and service assistants of users in Metaverses, can enable drivers and passengers to immerse themselves in 3D virtual services and spaces of UAV-assisted vehicular Metavers...
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Avatars, as promising digital representations and service assistants of users in Metaverses, can enable drivers and passengers to immerse themselves in 3D virtual services and spaces of UAV-assisted vehicular Metaverses. However, avatar tasks include a multitude of human-to-avatar and avatar-to-avatar interactive applications, e.g., augmented reality navigation,which consumes intensive computing resources. It is inefficient and impractical for vehicles to process avatar tasks locally. Fortunately, migrating avatar tasks to the nearest roadside units(RSU)or unmanned aerial vehicles(UAV) for execution is a promising solution to decrease computation overhead and reduce task processing latency, while the high mobility of vehicles brings challenges for vehicles to independently perform avatar migration decisions depending on current and future vehicle status. To address these challenges, in this paper, we propose a novel avatar task migration system based on multi-agent deep reinforcement learning(MADRL) to execute immersive vehicular avatar tasks dynamically. Specifically, we first formulate the problem of avatar task migration from vehicles to RSUs/UAVs as a partially observable Markov decision process that can be solved by MADRL algorithms. We then design the multi-agent proximal policy optimization(MAPPO) approach as the MADRL algorithm for the avatar task migration problem. To overcome slow convergence resulting from the curse of dimensionality and non-stationary issues caused by shared parameters in MAPPO, we further propose a transformer-based MAPPO approach via sequential decision-making models for the efficient representation of relationships among agents. Finally, to motivate terrestrial or non-terrestrial edge servers(e.g., RSUs or UAVs) to share computation resources and ensure traceability of the sharing records, we apply smart contracts and blockchain technologies to achieve secure sharing management. Numerical results demonstrate that the proposed approach
To deal with the discrepancy between global and local objectives in the federated learning invoked by the non-independent, identically distributed (non-IID) data and mitigate the impact of catastrophic forgetting in t...
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