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Michael Coto Giorgio Divitini Avishek Dey Satheesh Krishnamurthy Najeeb Ullah Cate Ducati R. Vasant Kumar 《Materials Today Chemistry》2017
A highly efficient black TiO2-Ag photocatalytic nanocomposite, active under both UV and visible light illumination, was synthesized by decorating the surface of 25 nm TiO2 particles with Ag nanoparticles. The material was obtained via a rapid, one-pot, simple (surfactant and complexing agent free) chemical reduction method using silver nitrate and formaldehyde as a metal salt and reducing agent, respectively. The nanocomposite shows an increase of over 800% in the rate of photocatalytic methylene blue dye degradation, compared to commercial unmodified TiO2, under UV-VIS illumination. Unlike pure TiO2, the nanocomposite exhibits visible light activation, with a corresponding drop in optical reflectance from 100% to less than 10%. The photocatalytic properties were shown to be strongly enhanced by post-reduction annealing heat treatments in air, which were observed to decrease, rather than coarsen, silver particle size, and increase particle distribution. This, accompanied by a variation in the silver surface oxidation states, appear to dramatically affect the photocatalytic efficiency under both UV and visible light. This highly active photocatalyst could have wide ranging applications in water and air pollution remediation and solar fuel production. 相似文献
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Wavelet-based methods are reviewed, and their advantages in comparison to standard approaches are outlined. Then, a wavelet analysis is performed to investigate parametric vibrations of flexible plates under a sinusoidal load. In particular, a scenario leading from regular motion to chaos is analyzed 相似文献
176.
轻质、高精度的柔性多体系统被广泛应用于实际工程领域中.由于实际设计公差、制造误差及环境温度等多种不确定因素的存在,使得柔性多体系统的结构参数(物理参数和几何参数)表现出随机性.具有随机结构参数的动力学模型能够客观地反映出真实系统的动力学行为,且结构参数的不确定性对空间柔性多体系统动力学响应的影响是不容忽视的.针对具有多个随机参数的空间柔性多体系统,提出了一种基于广义alpha算法的非侵入式随机柔性多体系统动力学计算方法.采用绝对节点坐标公式(absolute node coordinate formulation, ANCF)来描述柔性体, 推导建立多体系统动力学模型.利用混沌多项式展开(polynomial chaos expansion, PCE)法构建系统随机动力学方程的代理模型,然后将随机响应面法(stochastic response surface method, SRSM)嵌入广义-alpha方法中,分别采用改进抽样的回归方法(regression method of improved sampling, RMIS)和单项求容积法则(Monte Carlo simulation, MCR)来确定样本点.将数值计算结果与蒙特卡洛模拟(Monte Carlo simulation, MCS)结果进行对比, 验证了所提算法的有效性.在相同的定积分精度的条件下,根据单项求容积法则确定的样本点的计算结果稳定性更强, 且其计算效率更高. 相似文献
177.
Principal parametric and three-to-one internal resonances of flexible beams undergoing a large linear motion 总被引:7,自引:0,他引:7
A set of nonlinear differential equations is established by using Kane‘s method for the planar oscillation of flexible beams undergoing a large linear motion. In the case of a simply supported slender beam under certain average acceleration of base, the second natural frequency of the beam may approximate the tripled first one so that the condition of 3 : 1 internal resonance of the beam holds true. The method of multiple scales is used to solve directly the nonlinear differential equations and to derive a set of nonlinear modulation equations for the principal parametric resonance of the first mode combined with 3 : 1 internal resonance between the first two modes. Then, the modulation equations are numerically solved to obtain the steady-state response and the stability condition of the beam. The abundant nonlinear dynamic behaviors, such as various types of local bifurcations and chaos that do not appear for linear models, can be observed in the case studies. For a Hopf bifurcation,the 4-dimensional modulation equations are reduced onto the central manifold and the type of Hopf bifurcation is determined. As usual, a limit cycle may undergo a series of period-doubling bifurcations and become a chaotic oscillation at last. 相似文献
178.
S. Faulhaber M.-W. Moon A.G. Evans 《Journal of the mechanics and physics of solids》2006,54(5):1004-1028
Residually compressed films and coatings are susceptible to buckle delamination. The buckles often have linear or telephone cord morphology. When the films are brittle, such buckles are susceptible to the formation of ridge cracks that extend along their length, terminating close to the propagating front. The ridge-cracked buckles are invariably straight-sided (not telephone cord) and differ in width. Buckle delaminations of this type occur on flat and curved substrates: having greatest technological relevance in the latter. They occur not only in single layer films but also in multilayers, such as thermal barrier systems. Establishing the mechanics of ridge-cracked buckle delaminations for multilayers on curved substrates serves two purposes. (a) It allows the prediction of buckle delamination and spalling for technologically important systems. (b) It provides a test protocol for measuring properties such as the delamination toughness of the interface and the stresses in the layers. Both objectives are addressed in the article: the latter by devising an inverse algorithm. Implementation of the algorithm is demonstrated for diamond-like carbon films on planar glass substrates and a thermal barrier multilayer on a curved superalloy substrate. 相似文献
179.
Hydrothermal Synthesis of Nickel Phosphate Nanorods for High‐Performance Flexible Asymmetric All‐Solid‐State Supercapacitors 下载免费PDF全文
Junhong Zhao Shaomei Wang Zhen Run Guangqin Zhang Weimin Du Huan Pang 《Particle & Particle Systems Characterization》2015,32(9):880-885
Ni20[(OH)12(H2O)6][(HPO4)8(PO4)4]·12H2O nanorods are successfully synthesized via a one‐pot hydrothermal reaction. A high‐performance flexible asymmetric all‐solid‐state supercapacitor based on the obtained Ni20[(OH)12(H2O)6][(HPO4)8(PO4)4]·12H2O nanorods (positive electrode) and graphene nanosheets (negative electrode) is successfully assembled. It is the first report of this nanomaterial applied for all‐solid‐state supercapacitors. Interestingly, a maximum volumetric energy density of 0.446 mW h cm?3 at a current density of 0.5 mA cm?2 and a maximum power density of 44.1 mW cm?3 at a current density of 6.0 mA cm?2 are achieved by the as‐assembled device. What's more, the device also shows excellent mechanical flexibility and little capacitance change after over 5000 charge/discharge cycles at a current density of 0.5 mA cm?2. 相似文献
180.
本文将硅(Si)衬底上外延生长的氮化镓(GaN)基发光二极管(LED)薄膜转移至含有柔性黏结层的基板上, 获得了不受衬底和支撑基板束缚的LED薄膜. 利用高分辨率X射线衍射仪(HRXRD)研究了薄膜转移前后的应力变化, 同时对其光致发光(PL)光谱的特性进行了研究. 结果表明: 硅衬底GaN基LED薄膜转移至柔性基板后, GaN受到的应力会由转移前巨大的张应力变为转移后微小的压应力, InGaN/GaN量子阱受到的压应力则增大; 尽管LED薄膜室温无损转移至柔性基板其InGaN阱层的In组分不会改变, 然而按照HRXRD倒易空间图谱通用计算方法会得出平均铟组发生了变化; GaN基LED薄膜从外延片转移至柔性基板时其PL谱会发生明显红移. 相似文献