The lack of tracking and storing capabilities for the results of web-based learning activities is an issue that remains unsolved. Transitions or interactions defined by teachers through a set of conditions still requi...
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ISBN:
(纸本)9781479931927
The lack of tracking and storing capabilities for the results of web-based learning activities is an issue that remains unsolved. Transitions or interactions defined by teachers through a set of conditions still require programming skills that stay far beyond the desired final results. In addition to this, authoring tools should bepowerful enough to let lecturers generate contents which are high-quality, interactive, and tuned to each student's cognitive preferences and progress. Availability and processing capabilities, or motivation, relevance, etc., must also be aspects to address in this context. For these reasons, this paper aims to review the existing web application authoring toolkits focusing on distance education. In particular, we analize their main features, requirements and issues, as well as the most promising areas for future improvemenst in this field.
The paper deals with robust model predictive control designed using recurrent neural network. A dynamic neural network is trained to act as the one-step ahead predictor, which is then used successively to obtain k-ste...
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The paper deals with robust model predictive control designed using recurrent neural network. A dynamic neural network is trained to act as the one-step ahead predictor, which is then used successively to obtain k-step ahead prediction of the plant output. Based on the neural predictor, the control law is derived solving a constrained optimization problem. The robustness of the considered predictive scheme is derived using the concept of an error model. Based on the developed robust model, a optimization problem is redefined. Two solutions are portrayed. The first one is to change the cost function in order to consider the robust model of the plant, while the second one is to impose constraints on the process output using derived uncertainty bands.
The Z-source neutral point clamped (NPC) inverters can realize buck-boost energy conversion with all satisfying advantages of the three-level inverters. A significant problem related to this topology is the fluctuatio...
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ISBN:
(纸本)9781479940318
The Z-source neutral point clamped (NPC) inverters can realize buck-boost energy conversion with all satisfying advantages of the three-level inverters. A significant problem related to this topology is the fluctuation of the neutral-point potential (NP). However, the previous modulation techniques for this topology cannot achieve the considerate stable voltage. In this paper, based on the analysis of the relationship among the shoot-through duty cycle and the NP voltage, the average NP current, switching frequency capacitor value, a new feed-forward compensator by modifying the shoot-through duty cycle which can improve to balance the NP voltage balancing is proposed. Meanwhile, in consideration of a low voltage gain caused by the NP voltage balance method, a new control method based on a maximum constant boost control method is proposed, which brings the benefits in both high voltage gain and low-frequency ripple. The considerate stable NP voltage and the high voltage gain have been proven in simulation and through experimental results from a prototype converter.
It is well known that in most bilateral teleoperation systems, variable time-delays arise in the communications. Motivated by this fact, the present work reports the extension to the (asymmetric) variable time-delays ...
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It is well known that in most bilateral teleoperation systems, variable time-delays arise in the communications. Motivated by this fact, the present work reports the extension to the (asymmetric) variable time-delays case of the adaptive controller for bilateral teleoperators with uncertain parameters and constant time-delays, reported in Nuño et al (2010) [Nuño, E., Ortega, R. and Basañez, L. (2010). An adaptive controller for nonlinear teleoperators. Automatica, 46(1), 155–159]. Compared to the previous work, the stability analysis does not rely on the cascade interconnection structure of the local and remote nonlinear dynamics and the linear interconnection map. Instead, the paper employs a different Lyapunov candidate function that incorporates a strictly positive term, the local and remote position error. With the only assumption that a bound of the time-delays is known, the paper also presents a sufficient condition that ensures the asymptotic convergence of position errors and velocities to zero. Some simulations, in free space and interacting with a stiff wall, illustrate the performance of the proposed control scheme in the presence of variable time–delays.
For the actual demand for carbon cycle research in China, from 2012 to 2013, we start the research and development on IPv6-based Chinese terrestrial ecosystem flux research network (CNGI/ChinaFLUX). IPv4/IPv6-based re...
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Due to wide frequency band, the long-distance communication is prone to be jammed by traditional radios. Furthermore, severe interference will lead to serious deterioration of performance. To solve this problem, the p...
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The use of FPGAs in the design of wireless sensor networks can improve the processing system performance so as to develop sensor nodes with powerful embedded processor. In fact, FPGA has a super-parallel processing ca...
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The use of FPGAs in the design of wireless sensor networks can improve the processing system performance so as to develop sensor nodes with powerful embedded processor. In fact, FPGA has a super-parallel processing capacity in data processing and its use and configuration is flexible. This allows intensive digital signal processing tasks like Fast Fourier Transforms to be implemented on the sensor node and this can even support intelligent applications and new security algorithms. This paper presents a wireless sensor network system that monitors and visualizes periodically the environment temperature. The proposed system consists of a base station node based on an FPGA DE2-70 and five sensor nodes having the architecture of the System-on-Chip CC2430.
Cloth is a flexible thin material with low stretch. Although large stiffness can reduce stretch to some extent, it degrades numerical computing stability. Introducing effective constraints into the system is another c...
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Cloth is a flexible thin material with low stretch. Although large stiffness can reduce stretch to some extent, it degrades numerical computing stability. Introducing effective constraints into the system is another common method to reduce stretch. In this paper, a novel constraint method is deduced and implemented. The bending deformation of cloth is firstly analyzed from micro-mesh view, based on which, constraint method is deduced. Then, constraint is combined with dynamic equation to simulate cloth. Overstretch of cloth is controlled at the same time realistic wrinkles and folds are maintained. Finally, based on this method, some experiments are conducted and the analysis and evaluation are given.
Supervisory control reconfiguration can handle the uncertainties including resource failures and task changes in discrete event systems. It was not addressed to exploit the robustness of closed-loop systems to accommo...
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