Dielectric ceramic capacitors, with the advantages of high power density, fast charge-discharge capability, excellent fatigue endurance, and good high temperature stability, have been acknowledged to be promising candidates for solid-state pulse power systems. This review investigates the energy storage performances of linear dielectric, relaxor ferroelectric, and antiferroelectric from the viewpoint of chemical modification, macro/microstructural design, and electrical property optimization. Research progress of ceramic bulks and films for Pb-based and/or Pb-free systems is summarized. Finally, we propose the perspectives on the development of energy storage ceramics for pulse power capacitors in the future.

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Progress and perspectives in dielectric energy storage ceramics

High-entropy enhanced capacitive energy storage

In this paper, a novel approach to design multifrequency self-diplexed single patch antennas is proposed This approach is based on a square microstrip patch antenna loaded with split ring resonators (SRRs) The working frequencies can be arbitrarily chosen and frequency ratios lower than 107 have been achieved In addition self-diplexing characteristics are also achieved between transmitting and receiving ports by including SRRs in the feeding lines Several prototypes have been manufactured and measured in the X-band showing good performance Received 17 December 2010, Accepted 17 January 2011, Scheduled 26 January 2011 Corresponding author: Javier Montero-de-Paz (jmontero@tscuc3mes) 48 Montero-de-Paz et al

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Multifrequency Self-Diplexed Single Patch Antennas Loaded with Split Ring Resonators

A fishnet based metamaterial (MTM) loaded rectangular microstrip patch antenna (RMPA) is proposed for THz applications. The negative refractive index of the MTM has been displayed at frequency range between 1.05 and 1.1 THz. This MTM can be used for improving the return loss, gain and radiation efficiency of RMPA. The return loss (S11), and gain are found as −57 and 3.57 dB, respectively. In addition, the bandwidth of −10 dB has been found as 8.2 %.

Fishnet based metamaterial loaded THz patch antenna

A theorem characterizing the property of the optimal solution is presented.A hybrid evolutionary algorithm (HEA) is proposed.Extreme machine learning is used to approximate the fitness of most individuals.Two heuristics are incorporated to generate a good initial population.The proposed algorithm is computationally effective. This paper considers the two-stage capacitated facility location problem (TSCFLP) in which products manufactured in plants are delivered to customers via storage depots. Customer demands are satisfied subject to limited plant production and limited depot storage capacity. The objective is to determine the locations of plants and depots in order to minimize the total cost including the fixed cost and transportation cost. However, the problem is known to be NP-hard. A practicable exact algorithm is impossible to be developed. In order to solve large-sized problems encountered in the practical decision process, an efficient alternative approximate method becomes more valuable. This paper aims to propose a hybrid evolutionary algorithm framework with machine learning fitness approximation for delivering better solutions in a reasonable amount of computational time. In our study, genetic operators are adopted to perform the search process and a local search strategy is used to refine the best solution found in the population. To avoid the expensive consumption of computational time during the fitness evaluating process, the framework uses extreme machine learning to approximate the fitness of most individuals. Moreover, two heuristics based on the characteristics of the problem is incorporated to generate a good initial population. Computational experiments are performed on two sets of test instances from the recent literature. The performance of the proposed algorithm is evaluated and analyzed. Compared with other algorithms in the literature, the proposed algorithm can find the optimal or near-optimal solutions in a reasonable amount of computational time. By employing the proposed algorithm, facilities can be positioned more efficiently, which means the fixed cost and the transportation cost can be decreased significantly, and organizations can enhance competitiveness by using the optimized facility location scheme.

Hybrid evolutionary algorithm with extreme machine learning fitness function evaluation for two-stage capacitated facility location problems

Giant energy storage density in lead-free dielectric thin films deposited on Si wafers with an artificial dead-layer

Accurately retrieving the constitutive effective parameters is the prerequisite for the research and application of metamaterials. When the constitutive effective parameters are retrieved from the transmission and reflection characteristics of metamaterials, the determination of the branch index m is a key but difficult step. In 2004, Chen et al. proposed a robust and effective retrieval method. But our study finds that this method may fail to determine the branch index m in some cases, which may occur not only in the resonance band but also in non-resonance bands. To circumvent this problem, an improved approach to determine the branch index m is proposed. By relaxing the constraint on m, the improved approach converts the determination of m to a constrained minimization problem, and thus a unique m can be determined. Two examples are presented to demonstrate the applicability and accuracy of the improved approach.

An Improved Approach to Determine the Branch Index for Retrieving the Constitutive Effective Parameters of Metamaterials

Metamaterials, which are composite materials constructed usually by periodic and artificial resonant structures, have been widely utilized in many fields including the antenna design. Quite different from popular methods of embedding an antenna inside a metamaterial or placing metamaterial plates in front of an antenna, this work explores using a metamaterial structure, the periodic split-ring resonator (SRR), to design radiation slots in a printed array antenna for high gain. A proposed array with 4×4 slots and working at 5.8 GHz has been automated designed by using the Genetic Algorithm (GA) in conjunction with the parallel computation on a cluster. Both results of numerical simulations and measurements demonstrate, in comparison with an array using conventional rectangular slots, that the proposed array with SRR slots possesses almost the same impedance bandwidth, side-lobe and cross polarization level, but the gain is improved from 18.7 dBi to 19.6 dBi.

A Novel Planar Printed Array Antenna with SRR Slots

A genetic metamaterial, whose periodic but irregular structure is completely designed by the Genetic Algorithm (GA) without a preexisting form, is presented and applied to improve the gain of a patch antenna. This metamaterial is fabricated on a printed circuit board (PCB), and consists of unit cells periodically distributed on the PCB. Each unit cell is gridded into 10 × 10 square pixels, whose dimensions as well as conducting or nonconducting properties are determined by the GA. Four layers of such a genetic metamaterial are placed in front of a rectangular patch antenna. At the working frequency of 3.6 GHz, both the simulation and the measurement results show that the genetic metamaterial layers have greatly improved the gain of the patch antenna over 4.1 dB (from 8.3 to 12.4 dBi), and thus the corresponding aperture efficiency is increased from 38 to 95%; meanwhile, results of an equivalent parameter retrieval show that the GA designed genetic metamaterial possesses the double-negative (DNG, i.e. both...

A genetic metamaterial and its application to gain improvement of a patch antenna

Thickness-dependence of growth rate, dielectric response, and capacitance properties in Ba0.67Sr0.33TiO3/LaNiO3 hetero-structure thin films for film capacitor applications

Xiaoyang Chen

Papers

Giant energy storage density in lead-free dielectric thin films deposited on Si wafers with an artificial dead-layer

An Improved Approach to Determine the Branch Index for Retrieving the Constitutive Effective Parameters of Metamaterials

A Novel Planar Printed Array Antenna with SRR Slots

A genetic metamaterial and its application to gain improvement of a patch antenna

Thickness-dependence of growth rate, dielectric response, and capacitance properties in Ba0.67Sr0.33TiO3/LaNiO3 hetero-structure thin films for film capacitor applications