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排序方式: 共有921条查询结果,搜索用时 15 毫秒
61.
Quanlong Yang Sergey Kruk Yuehong Xu Qingwei Wang Yogesh Kumar Srivastava Kirill Koshelev Ivan Kravchenko Ranjan Singh Jiaguang Han Yuri Kivshar Ilya Shadrivov 《Advanced functional materials》2020,30(4)
All‐dielectric metasurfaces have become a new paradigm for flat optics as they allow flexible engineering of the electromagnetic space of propagating waves. Such metasurfaces are usually composed of individual subwavelength elements embedded into a host medium or placed on a substrate, which often diminishes the quality of the resonances. The substrate imposes limitations on the metasurface functionalities, especially for infrared and terahertz frequencies. Here a novel concept of membrane Huygens' metasurfaces is introduced. The metasurfaces feature an inverted design, and they consist of arrays of holes made in a thin membrane of high‐index dielectric material, with the response governed by the electric and magnetic Mie resonances excited within dielectric domains of the membrane. Highly efficient transmission combined with the 2π phase coverage in the freestanding membranes is demonstrated. Several functional metadevices for wavefront control are designed, including beam deflector, a lens, and an axicon. Such membrane metasurfaces provide novel opportunities for efficient large‐area metadevices, whose advanced functionality is defined by structuring rather than by chemical composition. 相似文献
62.
Chatterjee Saikat Li Donghui Leung Jackie Sengupta Joydeep Chattopadhyay Kinnor 《Metallurgical and Materials Transactions B》2017,48(2):1035-1044
Metallurgical and Materials Transactions B - Inert gas shrouding in tundish can result in the formation of a tundish open eye (TOE) due to the presence of reversed flows on the upper surface of the... 相似文献
63.
Effect of illumination on mobility has been studied from the photocurrent decay characteristics of thermally evaporated CdSe
thin films deposited on suitably cleaned glass substrate held at elevated substrate temperatures. The study indicates that
the mobilities of the carriers of different trap levels are activated due to the energy of incident illumination, which results
in the existence of two distinct trap levels. In each trap depth the energy of the trap increases linearly. It infers that
there is a linear distribution of traps of different energies below the conduction band. 相似文献
64.
A high piezoelectric transition temperature is indicated for present orthorhombic samples of lead meta-niobate (PbNb2O6) by the high value of the temperature (Tm) at which the real part (?′) of electrical permittivity peaks. It is 573 to 580°C. The imaginary component (?″) increases sharply at these temperatures. Cooling run after heating to 700°C gives changed values of ?′ and ?″ and Tm. Present work reports impedance spectroscopy (up to 700°C over 20 Hz to 5.5 MHz) and Differential Scanning Calorimetry or DSC on the pure orthorhombic phase, and, for the first time, on the pure rhombohedral phase. DSC shows an endothermic dip across Tm during heating and an exothermic peak during cooling for the orthorhombic sample only. 相似文献
65.
Ranjan Bhattacharya Susmita Bandyopadhyay 《The International Journal of Advanced Manufacturing Technology》2010,51(1-4):397-414
This paper focuses on the facility location problem with two conflicting objectives. We observe that minimization of the total cost of a particular echelon may lead to the increase in the total cost of a supply chain as a whole. Thus, these conflicting objectives are required to be met together from a supply chain perspective. We have solved the problem formulated in mixed nonlinear programming by a multi-objective evolutionary algorithm (MOEA) known as non-dominated sorting algorithm, or NSGA II in short. Numerical example is provided to show the effect of the algorithm on the solution. 相似文献
66.
Simultaneous sequestration of nitrate and phosphate from wastewater using a tailor‐made bacterial consortium in biofilm bioreactor
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Pallavi Mukherjee Chaitali Chanda Moumita Bhaumik Madhurima Ghosh Jaweria Sharmin Poulami Datta Srimoyee Banerjee Parthasarathi Barat Ashoke Ranjan Thakur Lalit Mohan Gantayet Indranil Mukherjee Shaon Ray Chaudhuri 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2018,93(5):1279-1289
67.
Selvarajoo T.A.L. Ranjan R. Kin-Leong Pey Lei-Jun Tang Chih Hang Tung Wenhe Lin 《Device and Materials Reliability, IEEE Transactions on》2005,5(2):190-197
The breakdown phenomena in SiO/sub x/N/sub y/ (EOT=20 /spl Aring/) gate dielectric under a two- stage constant voltage stress in inversion mode are physically analyzed with the aid of transmission electron microscopy. The results show that dielectric-breakdown-induced epitaxy (DBIE) remains as one of the major failure defects responsible for gate dielectric breakdown evolution even for a stress voltage as low as 2.5 V. Based on the results, the same failure mechanism i.e., presence of DBIE would be responsible for the degradation in ultrathin gate dielectrics for gate voltage below 2.5 V. It is believed that DBIE will be present in MOSFETs failed at nominal operating voltage. 相似文献
68.
Flow past a square cylinder at a Reynolds number of 21,400 has been studied numerically using the large-eddy simulation technique. A dynamic subgrid-scale stress model has been used for the small scales of turbulence. The time- and span-averaged axial and transverse velocities in the downstream of the cylinder are in good agreement with the experimental results. The distribution of turbulent normal and shear stresses is also well predicted. The coherent and incoherent components of turbulent fluctuations at some specified phases have been separated and their relative magnitudes downstream of the cylinder have been compared. The comparison shows more coherence in the near wake than the far wake, while the coherent and incoherent components are of comparable magnitude in the far wake. The far wake shows irregular phase-averaged structures. 相似文献
69.
70.
Sripati Ranjan Chaudhuri 《International Journal of Engineering Science》1979,17(12):1273-1281
Starting with a class of small deformations superposed on a finitely deformed state of a transversely isotropic elastic solid, we study a problem of small torsional vibration superposed on homogeneous finitely deformed state of a circular cylindrical rod made of transversely isotropic elastic material. It has been found that free vibration is possible and, due to anisotropy, the speed of propagation of waves of torsion along the cylinder is increased or decreased according as the initial stressed state is under tension or compression. 相似文献