Orthogonal learning particle swarm optimization

Particle swarm optimization (PSO) relies on its learning strategy to guide its search direction. Traditionally, each particle utilizes its historical best experience and its neighborhood’s best experience through linear summation. Such a learning strategy is easy to use, but is inefficient when searching in complex problem spaces. Hence, designing learning strategies that can utilize previous search information (experience) more efficiently has become one of the most salient and active PSO research topics. In this paper, we proposes an orthogonal learning (OL) strategy for PSO to discover more useful information that lies in the above two experiences via orthogonal experimental design. We name this PSO as orthogonal learning particle swarm optimization (OLPSO). The OL strategy can guide particles to fly in better directions by constructing a much promising and efficient exemplar. The OL strategy can be applied to PSO with any topological structure. In this paper, it is applied to both global and local versions of PSO, yielding the OLPSO-G and OLPSOL algorithms, respectively. This new learning strategy and the new algorithms are tested on a set of 16 benchmark functions, and are compared with other PSO algorithms and some state of the art evolutionary algorithms. The experimental results illustrate the effectiveness and efficiency of the proposed learning strategy and algorithms. The comparisons show that OLPSO significantly improves the performance of PSO, offering faster global convergence, higher solution quality, and stronger robustness

Development of a single-phase high frequency UPS with backup PEM fuel cell and battery

This paper presents a 300 W single-phase high frequency uninterrupted power supply (UPS) with backup proton exchange membrane fuel cell (PEMFC) and battery, DC/AC inverter, DC/DC converter, AC/DC rectifier, and AC/DC recharger. The principle and structure of the PEMFC/battery hybrid UPS system are introduced and discussed. Key practical techniques of the design are presented, including the design of the PEMFC generating system, the control technique of the AC/DC rectifier, AC/DC recharger, DC/AC inverter and DC/DC converter based on a microcomputer MC68HC11K4 and other integrated circuit chips. Experimental results show that during the switching process from battery to PEMFC, and vice versa, the UPS can provide an uninterrupted alternate voltage for the load, with low cost, low weight, small volume and size, great reliability and maintainability

Comprehensive control of proton exchange membrane fuel cell as backup power supply for UPS

To improve the performance of a proton exchange membrane fuel cell (PEMFC) stack, it is important to avoid the hydrogen and oxygen/air starvation of electrochemical reaction, prevent the dehydration and drying of the membrane, and track the output power. This paper conducts research in a comprehensive control strategy of the operation parameters of an uninterruptible power system (UPS) with backup PEMFC and battery power sources, such as the thermal management and control of operating temperature, pressures and mass flows of hydrogen and air for the PEMFC stack, switch of the power supply between PEMFC and battery for UPS, and the output power tracking of PEMFC. Based on the dynamic model of the anode and cathode flow system, the models of manifold and the performance curve, a detail model analysis is presented. A comprehensive control method is proposed and applied to the PEMFC system employed for the power source of UPS. The experimental results show that the comprehensive control method can effectively keep constant pressures of the inlet hydrogen and air, automatically switch the power supply between PEMFC and battery, reasonably improve the performance of the PEMFC through thermal management and control of operating temperature, and track the real-time changes of the output power and the distribution of the mass flows of hydrogen and oxygen/air

Current-conserving and gauge-invariant quantum ac transport theory in the presence of phonon

published_or_final_versio

Fast filtering image fusion

© 2017 SPIE and IS & T. Image fusion aims at exploiting complementary information in multimodal images to create a single composite image with extended information content. An image fusion framework is proposed for different types of multimodal images with fast filtering in the spatial domain. First, image gradient magnitude is used to detect contrast and image sharpness. Second, a fast morphological closing operation is performed on image gradient magnitude to bridge gaps and fill holes. Third, the weight map is obtained from the multimodal image gradient magnitude and is filtered by a fast structure-preserving filter. Finally, the fused image is composed by using a weighed-sum rule. Experimental results on several groups of images show that the proposed fast fusion method has a better performance than the state-of-the-art methods, running up to four times faster than the fastest baseline algorithm

Power converters and controllers for UPS applications with backup PEM fuel cell

This paper studies the practical cost-effective DC/DC converter, DC/AC inverter and AC/DC rectifier for an uninterruptible power supply (UPS) system with backup proton exchange membrane fuel cell (PEMFC). Furthermore, a comprehensive controller for the PEMFC is designed according to the change of the load, while the energy storage elements, such as battery and ultracapacitor, are chosen in order to compensate the slow dynamic response of PEMFC and to meet the sudden peak load energy demand. The designed power converters can supply high quality power with flexible conversion functions, leading to the establishment of reliable power management for UPS applications. Finally, a suitable control strategy and technique, capable of coping with the change of the load for PEMFC and realizing the energy managements of UPS hybrid system, is implemented. The performances of the proposed power converters and controllers are evaluated by experimental results, showing that the developed UPS system with backup PEMFC and battery power sources is suitable for industry applications. © 2008 IEEE

Privacy-Aware Adversarial Network in Human Mobility Prediction

As mobile devices and location-based services are increasingly developed in different smart city scenarios and applications, many unexpected privacy leakages have arisen due to geolocated data collection and sharing. User re-identification and other sensitive inferences are major privacy threats when geolocated data are shared with cloud-assisted applications. Significantly, four spatio-temporal points are enough to uniquely identify 95\% of the individuals, which exacerbates personal information leakages. To tackle malicious purposes such as user re-identification, we propose an LSTM-based adversarial mechanism with representation learning to attain a privacy-preserving feature representation of the original geolocated data (i.e., mobility data) for a sharing purpose. These representations aim to maximally reduce the chance of user re-identification and full data reconstruction with a minimal utility budget (i.e., loss). We train the mechanism by quantifying privacy-utility trade-off of mobility datasets in terms of trajectory reconstruction risk, user re-identification risk, and mobility predictability. We report an exploratory analysis that enables the user to assess this trade-off with a specific loss function and its weight parameters. The extensive comparison results on four representative mobility datasets demonstrate the superiority of our proposed architecture in mobility privacy protection and the efficiency of the proposed privacy-preserving features extractor. We show that the privacy of mobility traces attains decent protection at the cost of marginal mobility utility. Our results also show that by exploring the Pareto optimal setting, we can simultaneously increase both privacy (45%) and utility (32%)

Perfect State Transfer in Laplacian Quantum Walk

For a graph $G$ and a related symmetric matrix $M$, the continuous-time quantum walk on $G$ relative to $M$ is defined as the unitary matrix $U(t) = \exp(-itM)$, where $t$ varies over the reals. Perfect state transfer occurs between vertices $u$ and $v$ at time $\tau$ if the $(u,v)$-entry of $U(\tau)$ has unit magnitude. This paper studies quantum walks relative to graph Laplacians. Some main observations include the following closure properties for perfect state transfer: (1) If a $n$-vertex graph has perfect state transfer at time $\tau$ relative to the Laplacian, then so does its complement if $n\tau$ is an integer multiple of $2\pi$. As a corollary, the double cone over any $m$-vertex graph has perfect state transfer relative to the Laplacian if and only if $m \equiv 2 \pmod{4}$. This was previously known for a double cone over a clique (S. Bose, A. Casaccino, S. Mancini, S. Severini, Int. J. Quant. Inf., 7:11, 2009). (2) If a graph $G$ has perfect state transfer at time $\tau$ relative to the normalized Laplacian, then so does the weak product $G \times H$ if for any normalized Laplacian eigenvalues $\lambda$ of $G$ and $\mu$ of $H$, we have $\mu(\lambda-1)\tau$ is an integer multiple of $2\pi$. As a corollary, a weak product of $P_{3}$ with an even clique or an odd cube has perfect state transfer relative to the normalized Laplacian. It was known earlier that a weak product of a circulant with odd integer eigenvalues and an even cube or a Cartesian power of $P_{3}$ has perfect state transfer relative to the adjacency matrix. As for negative results, no path with four vertices or more has antipodal perfect state transfer relative to the normalized Laplacian. This almost matches the state of affairs under the adjacency matrix (C. Godsil, Discrete Math., 312:1, 2011).Comment: 26 pages, 5 figures, 1 tabl

A PEMFC/battery hybrid ups system for backup and emergency power applications

This paper presents the development of a proton exchange membrane fuel cell (PEMFC) and battery hybrid uninterruptible power system (UPS) for backup and emergency power applications. A sixty-cell PEMFC stack is employed as the main power source at normal load and a 3-cell lead-acid battery is employed as the auxiliary power of the UPS at overload or during the PEMFC startup. The PEMFC consists of two valves for the hydrogen input and output respectively, a mass flow controller to adjust the hydrogen mass flow, and a pressure sensor to control the hydrogen pressure, and their control units for the management of the whole system. The design procedures of the UPS hybrid system are discussed. Experimental setups are presented and the experimental results verify the performances of the PEMFC/battery hybrid power source and the UPS system under the condition of computer load. The developed UPS system proves to be a cost-effective solution for backup and emergency power applications. © 2007 IEEE