This paper reviews studies on the prediction of ductile fracture during metal forming using an ellipsoidal void model and some other models proposed by the author and some relevant studies. Section 2 discusses the res...
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Parallelogram flexure mechanism (PFM) is a common flexure module that is widely used as a building block in the design and manufacturing of flexure-based XY motion stages that provide in-plane degrees-of-freedom (DoFs...
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As a reinforcement technology that improves load-bearing ability and prevents injuries,assisted exoskeleton robots have extensive applications in freight transport and health *** perception of gait information by such...
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As a reinforcement technology that improves load-bearing ability and prevents injuries,assisted exoskeleton robots have extensive applications in freight transport and health *** perception of gait information by such robots is vital for their *** information is the basis for motion planning in assistive and collaborative ***,a wearable gait recognition sensor system for exoskeleton robots is *** sensor arrays based on laser-induced graphene are developed with flexibility and *** sensor units are integrated into an insole to detect real-time pressure at key plantar *** addition,the circuit hardware and the algorithm are designed to reinforce the sensor system with the capability of gait *** experimental results show that the accuracy of gait recognition by the proposed system is 99.85%,and the effectiveness of the system is further verified through testing on an exoskeleton robot.
This paper explores the eco-driving problem of parallel hybrid electric vehicles, intended to drive a certain distance within a limited amount of time, where the longitudinal vehicle velocity and powertrain controls a...
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This paper explores the eco-driving problem of parallel hybrid electric vehicles, intended to drive a certain distance within a limited amount of time, where the longitudinal vehicle velocity and powertrain controls are optimized to minimize the fuel consumption. In particular, we incorporate Pontryagin's Minimum Principle (PMP) and singular control theory in an optimization framework to find the fuel-optimal velocity and power-split control policy for the prime mover and the electric machine with global optimality guarantees. In addition, we present reformulations and derivations, so that the same problem can be solved jointly using another framework based on convex optimization, with the same global optimality properties, employing methods originally derived for timeoptimal control of race cars. Thereby, we formally show the equivalence between the eco-driving and the racing problem. We showcase both our frameworks with numerical solutions, drawing three comparisons: First, we solve the velocity and power-split problem, both sequentially and jointly, using the PMP framework. We show that the latter can improve the fuel consumption by 2.6 %. Second, we benchmark the PMP and the convex framework by solving the joint problem with both methods and observe a discrepancy of 0.14% in terms of the resulting fuel energy consumption. Finally, in a numerical study addressing the performance of both methods individually, we observe that the efficiency of the PMP and the convex framework are strongly dependent on the stopping criteria and the discretization step size, respectively. Authors
Computational fluid dynamics (CFD) and response surface methodology were used to optimize a two-stage cyclone separator with critical diameters of 0.3 m and 0.4 m for oil palm loose fruit collection. Interactions betw...
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Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm *** address these challenges,*** Hwan Ko and Taek-S...
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Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm *** address these challenges,*** Hwan Ko and Taek-Soo Kim’s team introduced a laserinduced phase separation and adhesion method for fabricating conductive hydrogels consisting of pure poly(3,4-ethylenedioxythiophene):polystyrene sulfonate on polymer *** laser-induced phase separation and adhesion treated conducting polymers can be selectively transformed into conductive hydrogels that exhibit wet conductivities of 101.4 S cm^(−1) with a spatial resolution down to 5μ***,they maintain impedance and charge-storage capacity even after 1 h of *** micropatterned electrode arrays demonstrate their potential in long-term in vivo signal recordings,highlighting their promising role in the field of bioelectronics.
The second law of thermodynamics asserts that energy diffuses from hot to *** resulting temperature gradients drive the efficiencies and failures in a plethora of ***,as the dimensionalities of materials shrink to the...
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The second law of thermodynamics asserts that energy diffuses from hot to *** resulting temperature gradients drive the efficiencies and failures in a plethora of ***,as the dimensionalities of materials shrink to the nanoscale regime,proper heat dissipation strategies becomemore challenging since the mean free paths of phonons become larger than the characteristic length *** leads to temperature gradients that are dependent on interfaces and boundaries,which ultimately can lead to severe thermal ***,we uncover a phenomenon which we refer to as‘phonon funneling’,that allows the control of phonon transport to preferentially direct phonon energy away from geometrically confined interfacial thermal bottlenecks and into localized colder *** phenomenon supersedes heat diffusion based on the macroscale temperature gradients,thus introducing a nanoscale regime in which boundary scattering increases the phonon thermal conductivity of thin films,an opposite effect than what is traditionally *** work advances the fundamental understanding of phonon transport at the nanoscale and the role of efficient scattering methods for enhancing thermal transport.
The composite propeller has attracted much interest due to its excellent mechanical properties such as high specific stiffness and high specific strength,hence there is an increasing interest in utilizing the composit...
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The composite propeller has attracted much interest due to its excellent mechanical properties such as high specific stiffness and high specific strength,hence there is an increasing interest in utilizing the composite materials to improve the hydrodynamic and structural performance of marine *** objective of this paper is to study the cavitation performance of composite propellers based on the unsteady simulation method considering the cavitation-composite structure *** typical cavitation patterns around the composite propeller are studied,which include blade sheet cavitation and tip vortex *** unsteady flow characteristics of tip vortex cavitation and structural dynamic response of composite propeller are studied,and the mechanism of composite propeller for the cavitation suppression and efficiency improvement is *** results show that compared with rigid propellers,composite propellers have smaller cavity volume and higher propulsion efficiency under the same *** unsteady cavitating flow characteristics under non-uniform wake are periodic,and the phase lag of hydrodynamic coefficients of composite propeller can be observed compared with that of the rigid *** bending-torsional coupling deformation of the composite propeller makes the pressure pulsation of the flow field gentler,which reduces the influence of the cavitation load on the composite propeller.
This manuscript presents an innovative methodology for the assessment of the friction torque of ball slewing *** methodology aims to overcome the limitations of state-of-the-art approaches,especially when the friction...
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This manuscript presents an innovative methodology for the assessment of the friction torque of ball slewing *** methodology aims to overcome the limitations of state-of-the-art approaches,especially when the friction torque is conditioned by the preload of the *** this end,the authors propose to simulate the preload scatter when solving the load distribution problem,prior to the friction torque *** preload scatter allows to simulate a progressive transition of the balls from a four-point contact state to a two-point contact *** implementing this capability into an analytical model,the authors achieve a successful correlation with experimental ***,depending on the stiffness of the structures to which the bearing is assembled,it is demonstrated that the rigid ring assumption can lead to inaccurate friction torque results when a tilting moment is *** methodology described in this research work is meant to have a practical ***,the manuscript provides guidelines about how to use and tune the analytical model to get a reliable friction torque prediction tool.
Short driving ranges and low braking energy recovery efficiencies are two recognized technical bottlenecks to be overcome in electric vehicles. In this paper, a novel electromechanical-hydraulic coupling system is pro...
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Short driving ranges and low braking energy recovery efficiencies are two recognized technical bottlenecks to be overcome in electric vehicles. In this paper, a novel electromechanical-hydraulic coupling system is proposed and integrated as a powertrain for electric vehicles, which can assist the electric vehicle to fully utilize its braking energy. The hydraulic regenerative braking force and electric regenerative braking force can provide all the braking needs using the medium and small braking intensities. Furthermore, an improved compound brake control strategy based on the braking force distribution is proposed and simulated. The results show that under the premise of ensuring braking stability, the electromechanical-hydraulic coupling driving electric vehicle can adapt to various working conditions with excellent energy-saving results. The hydraulic accumulator recovery efficiency is above 99%, and the state of charge consumption rate of the battery pack can be reduced by more than 9%. More importantly, the proposed hybrid power system can significantly improve the driving range and energy efficiency, as well as reduce the consumers' mileage anxiety in electric vehicles.
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