Dilute nitride GaNP is potentially useful as the top junction in dual-junction solar cells on Si because it has a tunable direct-bandgap and small lattice mismatch with Si. Investigations on GaP are the first step tow...
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ISBN:
(纸本)9781509019656
Dilute nitride GaNP is potentially useful as the top junction in dual-junction solar cells on Si because it has a tunable direct-bandgap and small lattice mismatch with Si. Investigations on GaP are the first step toward this goal. Our best GaNP solar cell on GaP ([N] = 1.8%, Eg = 2.05 eV) achieves an efficiency of 7.9%, which is 3 times higher than the most efficient GaP solar cell to date and higher than other solar cells with similar direct bandgap (InGaP, GaAsP). We also report GaP/GaNP core/shell microwire solar cells utilizing top-down reactiveion etching to create the GaP cores and molecular beam epitaxy to create the GaNP shells. Systematic studies of cell performance over a series of microwire lengths, array periods, and sidewall morphologies, examined by transmission electron microscopy, were conducted to shed light on performance-limiting factors and to optimize the cell efficiency.
Humans sense of touch consists in a complexity of sensors and nervous system. The information inferred by this system enables the daily dexterous manipulation tasks. In biological systems, there is no conscious priori...
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The standard treatment of quantum corrections to semiclassical electronic conduction assumes that charge carriers propagate many wavelengths between scattering events, and succeeds in explaining multiple phenomena (we...
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This paper describes the usage of the Matlab/Simulink and Ptolemy II environments as learning tools in the implementation of simulation models, which represent the decentralized multi-loop control system proposed for ...
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ISBN:
(纸本)9789897581083
This paper describes the usage of the Matlab/Simulink and Ptolemy II environments as learning tools in the implementation of simulation models, which represent the decentralized multi-loop control system proposed for a fouling detection didactic platform. The platform is treated as a two-input two-output (TITO) plant with time delay, i.e., the voltage and current as the plant inputs and the flow and preßure as the plant outputs. In both the software environments, the control system is modeled as a cyber-physical system (CPS). Constructive details of each simulation model are shown, even as the main advantages and disadvantages of each learning tool are discußed and evaluated by engineering students.
An unidirectional single-phase three-wire rectifier is proposed in this paper. Such a proposed topology is composed of a non-controlled leg, two controlled legs and a capacitor bank. A suitable model and control strat...
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ISBN:
(纸本)9781509007387
An unidirectional single-phase three-wire rectifier is proposed in this paper. Such a proposed topology is composed of a non-controlled leg, two controlled legs and a capacitor bank. A suitable model and control strategy of the system, including a synchronization method, are proposed as well. The synchronization method, associated with the PWM strategy, imposes the grid currents to have the same phase angle of the generated voltages by rectifier. This method ensures sinusoidal grid currents and mitigate the zero-crossover distortions normally caused by the use of diodes. A comprehensive comparison with two conventional configurations is also presented in this paper. Simulation and experimental results are also presented for validation purposes.
As the new generation of smart sensors is evolving towards high sampling acquisitions systems, the amount of information to be handled by learning algorithms has been increasing. The Graphics Processing Unit (GPU) arc...
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As the new generation of smart sensors is evolving towards high sampling acquisitions systems, the amount of information to be handled by learning algorithms has been increasing. The Graphics Processing Unit (GPU) architectures provide a greener alternative with low energy consumption for mining big-data, harnessing the power of thousands of processing cores in a single chip, opening a widely range of possible applications. Here, we design a novel evolutionary computing GPU parallel function evaluation mechanism, in which different parts of time series are evaluated by different processing threads. By applying a metaheuristics fuzzy model in a low-frequency data for household electricity demand forecasting, results suggested that the proposed GPU learning strategy is scalable as the number of training rounds increases.
The challenging problem of forecasting a given time series as accurately as possible is reality in different areas of expertise. The requirement of achieving reliable forecasts, for assisting the new generation of sof...
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ISBN:
(纸本)9781509006212
The challenging problem of forecasting a given time series as accurately as possible is reality in different areas of expertise. The requirement of achieving reliable forecasts, for assisting the new generation of soft sensors, requests the development of novel smart mechanisms to be integrated into the available forecasting models. This current paper improves the previous work of Coelho et al. [1], [2], introduced in the 2014 WCCI, which introduced a Hybrid Self-adaptive Forecasting Model (HFM), calibrated using an evolutionary metaheuristic. Here, an expert input selection assisted by the use of Neighborhood Structures is used for learning the dataset provide in the CIF 2016 forecasting competition. Two different metaheuristic algorithms are used for training the HFM, computational experiments are conducted for optimizing both models. By selecting the maximum lag to be used by our model and, consequently, defining a rate of training cycles, we calibrate the HFM in order to minimize Symmetric Mean Absolute Percentage Errors. Blind forecasts generated by the model will be submit to the competition.
In industrial systems' simulated environments the assimilation of technical procedures by the operators under training is enhanced by reproducing similar to real situations experienced in the workplace. The experi...
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ISBN:
(纸本)9789897581205
In industrial systems' simulated environments the assimilation of technical procedures by the operators under training is enhanced by reproducing similar to real situations experienced in the workplace. The experience and learning acquired in simulators is directly related to the quality and realism of the proposed training scenarios. On the other hand, the experience acquired is even more conducive to good working practices when it involves situations known to lead into errors. Often training scenarios are dependent on the tutor's experience and the knowledge of operator difficulties in the work environment. This paper proposes a systematic approach for building training scenarios to be simulated, based on the analysis and reproduction of situations described in the working environment error reports. This approach is based on the instantiation of ontologies built for both domains, covering the knowledge on both the error situations and operator training scenarios. This study is focused in the domain of electric power systems operation.
This work introduces a family of Current Source Converters (CSCs) that allows to control single-phase AC converters with two outputs independently sharing the same DC-bus. It is presented four different topologies whi...
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ISBN:
(纸本)9781467395519
This work introduces a family of Current Source Converters (CSCs) that allows to control single-phase AC converters with two outputs independently sharing the same DC-bus. It is presented four different topologies which have their own advantages and disadvantages compared to each other. The comparison criterias are the total number of switches, the number of conducting switches per switching cycle, quadrant operations and DC-bus current. One of the topologies needs to always have four conducting switches with full-quadrant operation (named Fq4c), while another topology (Lq2c) needs only two, however with limited-quadrant operation. The last two presented topologies have three conducting switches in a switching period, one with full-quadrant operation (Fq3c) and another with limited-quadrant operation (Lq3c). Also it is presented the Scalar Pulse Width Modulations (SPWMs) to control each converter with switching optimization. Details of the topologies, operation and modulation logic are presented. Simulations and experimental results are provided to validate the theoretical approach.
Classification of voltage disturbances in power systems is essential for modern society and can be very demanding according to the used method or the aimed accuracy. This paper presents a new intelligent approach aime...
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