The influence of the microstructure on mechanical properties and corrosion behavior of the Mg–1.21Li–1.12Ca–1Y alloy was investigated using OM, SEM, XRD, EPMA, EDS, tensile tests and corrosion measurements. The res...
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The influence of the microstructure on mechanical properties and corrosion behavior of the Mg–1.21Li–1.12Ca–1Y alloy was investigated using OM, SEM, XRD, EPMA, EDS, tensile tests and corrosion measurements. The results demonstrated that the microstructure of the Mg–1.21Li–1.12Ca–1Y alloy was characterized by α-Mg substrate and intermetallic compounds Mg2 Ca and Mg24Y5. Most of the fine Mg2 Ca particles for the as-cast alloy were distributed along the grain boundaries, while for the as-extruded along the extrusion direction. The Mg24Y5 particles with a larger size than the Mg2 Ca particles were positioned inside the grains. The mechanical properties of Mg–1.21Li–1.12Ca–1Y alloy were improved by the grain refinement and dispersion strengthening. Corrosion pits initiated at the α-Mg matrix neighboring the Mg2 Ca particles and subsequently the alloy exhibited general corrosion and filiform corrosion as the corrosion product layer of Mg(OH)2and Mg CO3 became compact and thick.
To design a control strategy for iLeg, an exoskeleton robot developed for lower limb rehabilitation aiming at investigating the feasibility of integrating functional electrical stimulation (FES) with robot-based rehab...
To design a control strategy for iLeg, an exoskeleton robot developed for lower limb rehabilitation aiming at investigating the feasibility of integrating functional electrical stimulation (FES) with robot-based rehabilitation training, an FES-assisted training strategy combined with impedance control, has been proposed in this paper. Through impedance control, an active compliance of the robot is established, and the patient’s voluntary effort to accomplish the training task is inspired. During the training process, the patient’s related muscles are applied with FES which provides an extra assistance to the patient. The intensity of the FES is properly chosen in order to induce a desired active torque which is proportional to the voluntary effort extracted from the electromyography signals of the related muscles using back propagation neural networks. This kind of enhancement serves as a positive feedback which reminds the patient of the correct attempt to fulfill the desired motion. FES control is conducted by a combination of neural network-based feedforward controller and a PD feedback controller. Simulation conducted using Matlab and the experiment with a spinal cord injury subject and a healthy subject have shown satisfactory results which verify the feasibility of this control strategy.
An introduction is presented in which the editor discusses the theme of the periodical based on learning in nonstationary and evolving environments along with changes in the editorial board and also offers brief profi...
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An introduction is presented in which the editor discusses the theme of the periodical based on learning in nonstationary and evolving environments along with changes in the editorial board and also offers brief profiles of associate editors including Sander Bohte, Preben Kidmose, and Peter Tino.
In this paper, a model-free and effective approach is proposed to solve infinite horizon optimal control problem for affine nonlinear systems based on adaptive dynamic programming technique. The developed approach, re...
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The rapid development of vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communications calls for highly spectral efficient communication techniques under time-selective channels. Spatial modulation (SM) facili...
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The rapid development of vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communications calls for highly spectral efficient communication techniques under time-selective channels. Spatial modulation (SM) facilitates flexible trade-off between spectral and energy efficiency. In this paper, we propose a novel modulation technique based on SM for V2X, which discards the requirement of channel state information (CSI) at the receiver and exhibits enhanced robustness against time-selective fading and Doppler effects. Our proposed scheme tailors differential modulation to SM and is named differential spatial modulation (DSM). Monte Carlo simulations are carried out to demonstrate the advantage of the new scheme in terms of bit error rate (BER) performance for both point-to-point and dual-hop amplify-and-forward (AF) relaying systems in V2X channels.
In this paper,the nonlinear H guidance law design is proposed for the near space interceptor(NSI)based on Galerkin simultaneous policy update algorithm(GSPUA).Initially,the nonlinear H guidance law design problem for ...
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ISBN:
(纸本)9789881563842
In this paper,the nonlinear H guidance law design is proposed for the near space interceptor(NSI)based on Galerkin simultaneous policy update algorithm(GSPUA).Initially,the nonlinear H guidance law design problem for the NSI is converted to solve the Hamilton-Jacobi-Isaacs(HJI)equation,which is notoriously difficult to solve both numerically and *** the two-player zero-sum differential game theory,where the control player desires to minimize the cost function and the disturbance player desires to maximize ***,a simultaneous policy update algorithm(SPUA)is developed to solve the HJI equation,in which the control and disturbance policies are updated ***,the SPUA is implemented based on the Galerkin’s method,where the Lyapunov function equations(LFEs)in the iterative process of SPUA are ***,simulation results on the NSI demonstrate that the proposed nonlinear H guidance law is effective.
In search auctions, when the total budget for an advertising campaign during a certain promotion period is determined, advertisers have to distribute their budgets over a series of sequential temporal slots (e.g., dai...
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In search auctions, when the total budget for an advertising campaign during a certain promotion period is determined, advertisers have to distribute their budgets over a series of sequential temporal slots (e.g., daily budgets). However, due to the uncertainties existed in search markets, advertisers can only obtain the value range of budget demand for each temporal slot based on promotion logs. In this paper, we present a stochastic model for budget distribution over a series of sequential temporal slots during a promotion period, considering the budget demand for each temporal slot as a random variable. We study some properties and present feasible solution algorithms for our budget model, in the case that the budget demand is characterized either by uniform random variable or normal random variable. We also conduct some experiments to evaluate our model with the empirical data. Experimental results show that the budget demand is more likely to be normal distributed than uniform distributed, and our strategy can outperform the baseline strategy commonly used in practice.
The paper presents a new approach on haptic interface control for NAO robotic hand. The haptic teleoperation of NAO robot hand raises some issues, mapping the haptic device dynamic being the most important. The mappin...
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The paper presents a new approach on haptic interface control for NAO robotic hand. The haptic teleoperation of NAO robot hand raises some issues, mapping the haptic device dynamic being the most important. The mapping was achieved through Neural Network by determining a dynamic gain of robot haptic feedback. The results lead to the achievement of the haptic intelligent interfaces for the NAO robot hand control which can be integrated into an innovative haptic robot controlsystem.
The intersection models, such as delay models and queuing length models, are the foundations of optimal signal timing for urban intersection. Lack of the field data of intersection, it is highly difficult to calibrate...
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