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991.
本文在介绍了模拟控制系统中最常用的PID调节的数学模型的基础上,数字化离散后得到了该算法的数学离散模型。详细介绍了该数字化算法在自动化测试系统中的设计流程和部分举例程序。 相似文献
992.
Xinning Luan Ying Wang 《材料科学技术学报》2014,30(9):839-846
Hydrogen titanate has been considered as a promising lithium intercalation material due to its unique layered structure. In the present work, we fabricate 2D graphene/hydrogen titanate hybrid nanosheets for application as anode materials in lithium-ion batteries. H2Ti307 nanosheets are synthesized by exfoliation of a layered precursor via interacting bulky tetrabutylammonium (TBA+) cations, followed by ion exchange with Na+ ions and washing with water. The as-prepared hydrogen titanate nanosheets are well-dispersed exhibiting ultra-thin thickness with a lateral size up to a few micrometers. The sample is then annealed at 450, 650 Rnd 850 ℃, to optimize its Li+-intercalation property. Heating at 450 ℃ leads to well-crystallized hydrogen titanate with a trace amount of TiO2. Heating at 650 and 850 ℃ results in mixed sodium titanates, since some sodium ions in the interlayer structure cannot be washed away and become chemically bonded to [TiO6] octahedra at high temperatures. Electrochemical properties of all the four samples are then evaluated by charged/discharged for 100 electrochemical cycles at 0.01-2.5 V vs. Li+/Li at a specific current of 170 mA g-1. The unannealed hydrogen titanate delivers the highest initial discharge capacity of 130.5 mA h g-l, higher than 124.6 mA h g-1 from hydrogen titanate annealed at 450 ℃, as well as 101.3 and 63.8 mA h g-1 from hydrogen titanate annealed at 650 and 850℃, respectively, due to the high surface area from well-dispersed unannealed nanosheets. However, after 100 electrochemical cycles, well-crystallized hydrogen titanate annealed at 450 ℃ retain the highest charge capacity of 115.2 mA h g-1, corresponding to a capacity retention of 92.5%, while unannealed hydrogen titanate exhibits a final capacity of 72.1 mA h g-1 and a capacity retention of only 55.2%. To further improve energy density of lithium-ion battery, graphene/hydrogen titanate hybrid nanosheets are fabricated by adding graphene nanosheets into hydrogen titanates. The initial charge cap 相似文献
993.
Nanogenerators: Self‐Powered Cardiac Pacemaker Enabled by Flexible Single Crystalline PMN‐PT Piezoelectric Energy Harvester (Adv. Mater. 28/2014) 下载免费PDF全文
994.
Nanoparticles: Spontaneous Organization of Inorganic Nanoparticles into Nanovesicles Triggered by UV Light (Adv. Mater. 32/2014) 下载免费PDF全文
995.
Epitaxial Growth of Molecular Crystals on van der Waals Substrates for High‐Performance Organic Electronics 下载免费PDF全文
996.
997.
998.
Self‐Powered Cardiac Pacemaker Enabled by Flexible Single Crystalline PMN‐PT Piezoelectric Energy Harvester 下载免费PDF全文
999.
Jeong Ho Mun Seung Keun Cha Hyowook Kim Hyoung‐Seok Moon Ju Young Kim Hyeong Min Jin Young Joo Choi Jeong Eun Baek Jonghwa Shin Sang Ouk Kim 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(18):3742-3749
Ordered metal nanopatterns are crucial requirements for electronics, magnetics, catalysts, photonics, and so on. Despite considerable progress in the synthetic route to metal nanostructures, highly ordered metal nanopatterning over a large‐area is still challenging. Nanodomain swelling block copolymer lithography is presented as a general route to the systematic morphology tuning of metal nanopatterns from amphiphilic diblock copolymer self‐assembly. Selective swelling of hydrophilic nanocylinder domains in amphiphilic block copolymer films during metal precursor loading and subsequent oxygen based etching generates diverse shapes of metal nanopatterns, including hexagonal nanoring array and hexagonal nanomesh and double line array in addition to common nanodot and nanowire arrays. Solvent annealing condition of block copolymer templates, selective swelling of hydrophilic cylinder nanodomains, block copolymer template thickness, and oxygen based etching methods are the decisive parameters for systematic morphology evolution. The plasmonic properties of ordered Au nanopatterns are characterized and analyzed with finite differential time domain calculation. This approach offers unprecedented opportunity for diverse metal nanopatterns from commonly used diblock copolymer self‐assembly. 相似文献
1000.
Yun Mao Jun Peng Ying Guo Moon Ho Lee 《Circuits, Systems, and Signal Processing》2014,33(5):1491-1505
Motivated by the center weighted Hadamard matrix, we propose an improved algorithm for the fast fractional jacket transform (FRJT) based on eigendecomposition of the fractional jacket matrix (FRJM). Employing a matrix diagonalization transformation that decomposes a matrix of large size into products of the matrices composed of eigenvectors and eigenvalues, an FRJM of large size can be fast factored into products of several sparse matrices in a recursive fashion. To generate an FRJM of large size, an algorithm for the factorable FRJM can be conveniently designated with a reduced computational complexity in terms of additions and multiplications. Since the proposed FRJM itself concerns interpretation as a suitable rotation in the time-frequency domain, it is applicable for optics and signal processing. 相似文献