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121.
122.
Yu. N. Kazantsev G. A. Kraftmakher V. P. Mal’tsev V. S. Solosin 《Journal of Communications Technology and Electronics》2018,63(8):841-849
The amplitude and phase of the reflection coefficient of periodic arrays of electrically conducting elements in the form of double and single split rings are determined for two orientations of these rings, corresponding to magnetic (H) and magnetoelectric (HE) excitation. It is shown that, in the case of the HE-excitation of the rings, the arrays possess the properties of an artificial magnetic conductor or a high-impedance surface. The electric and magnetic fields near the arrays are calculated, and the dependence of the impedance on the distance between the array and the plane in which the impedance is determined is obtained. It is shown that the maximum of the impedance is in close vicinity of the array and can amount to tens of thousands of ohms. The feasibility of implementing a modified Salisbury radio absorber of small thickness by means of such arrays is shown theoretically and experimentally. It is also shown that, under illumination of an array of limited dimensions by a closely placed dipole, the screening effect reaches –30 dB with good matching of the dipole to the feed line (the reflection coefficient in the line is less than –20 dB). 相似文献
123.
Climate change impacts on natural resources and communities: A geospatial approach for management
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Adikanda Ojha Ajit Kumar Pattnaik Jajnaseni Rout 《Lakes & Reservoirs: Research and Management》2018,23(1):34-42
Climate change causes environmental depletion, with threats to the global economy. The health and productivity of ecosystems underpin agriculture, with stable ecosystems being the foundation for economic livelihoods and food security. This study proposes adaptation measures, using geospatial technology, for conserving natural resources and improving livelihoods of the local community from climate change scenarios. Planning, policy decisions and resultant programmes are required for natural resource management, which must be based on broad citizen participation and the engagement of rural communities. The suggested adaptation measures will help the planning system to regulate development of natural resources and the socio‐economic environment. The major natural resources in the environment are land and water, both of which can be severely degraded by human interventions, as well as climate change. Various thematic maps are prepared with the use of geospatial technology, in order to be helpful for site‐suitability analysis directed to the preparation of land and water management action plans for socio‐economic development. The study area is a micro‐watershed of the catchment of Ansupa Lake in the Cuttack District of Odisha, India. To reduce climate change impacts on natural resources and economic livelihoods, some adaptation measures have been proposed (e.g., 68.9 ha for afforestation.; 13.94 ha for gap plantations and agro‐horticulture; 389.62 ha for farm ponds and renovation of existing ponds for pisciculture and duckery activities, etc.; 11.33 ha for land management, along with five bore wells, eight dug wells, 51 LBS/check dams, and four WHSs, etc., for water management for sustainable use). 相似文献
124.
A. G. Mal’chik S. A. Kuznetsova S. O. Kryuchkova V. V. Kozik 《Inorganic Materials》2017,53(9):994-1003
Ta2O5–SiO2 composites containing 10, 50, and 90 wt % SiO2 have been prepared by a sol–gel process in ethanolic solutions of tantalum(V) chloride with tetraethyl orthosilicate. The physicochemical aspects of their formation have been studied by IR spectroscopy, X-ray diffraction, X-ray microanalysis, and thermal analysis in combination with mass spectrometry. The results demonstrate that the SiO2 content of the Ta2O5–SiO2 composites influences the uniformity of the tantalum and oxygen distributions on the surface of the materials and that heat-treatment conditions influence their crystallinity. 相似文献
125.
Ajit Panesar David Brackett Ian Ashcroft Ricky Wildman Richard Hague 《International journal for numerical methods in engineering》2017,111(7):676-700
This work investigates the use of hierarchical mesh decomposition strategies for topology optimisation using bi‐directional evolutionary structural optimisation algorithm. The proposed method uses a dual mesh system that decouples the design variables from the finite element analysis mesh. The investigation focuses on previously unexplored areas of these techniques to investigate the effect of five meshing parameters on the analysis solving time (i.e. computational effort) and the analysis quality (i.e. solution optimality). The foreground mesh parameters, including adjacency ratio and minimum and maximum element size, were varied independently across solid and void domain regions. Within the topology optimisation, strategies for controlling the mesh parameters were investigated. The differing effects of these parameters on the efficiency and efficacy of the analysis and optimisation stages are discussed, and recommendations are made for parameter combinations. Some of the key findings were that increasing the adjacency ratio increased the efficiency only modestly – the largest effect was for the minimum and maximum element size parameters – and that the most dramatic reduction in solve time can be achieved by not setting the minimum element size too low, assuming mapping onto a background mesh with a minimum element size of 1. © 2016 The Authors. International Journal for Numerical Methods in Engineering Published by John Wiley & Sons, Ltd. 相似文献
126.
Konopel’ko L. A. Efremova O. V. Kadis R. L. Klimov A. Yu. Kolobova A. V. Mal’ginov A. V. Chubchenko Ya. K. 《Measurement Techniques》2020,62(10):915-922
Measurement Techniques - The preparation of formaldehyde gas mixtures required for metrological assurance of air pollution control is an urgent task. Methods for the preparation of gas mixtures of... 相似文献
127.
Rajib Paul Feng Du Liming Dai Yong Ding Zhong Lin Wang Fei Wei Ajit Roy 《Advanced materials (Deerfield Beach, Fla.)》2019,31(13)
Sustainable and cost‐effective energy generation has become crucial for fulfilling present energy requirements. For this purpose, the development of cheap, scalable, efficient, and reliable catalysts is essential. Carbon‐based heteroatom‐doped, 3D, and mesoporous electrodes are very promising as catalysts for electrochemical energy conversion and storage. Various carbon allotropes doped with a variety of heteroatoms can be utilized for cost‐effective mass production of electrode materials. 3D porous carbon electrodes provide multiple advantages, such as large surface area, maximized exposure to active sites, 3D conductive pathways for efficient electron transport, and porous channels to facilitate electrolyte diffusion. However, it is challenging to synthesize and functionalize isotropic 3D carbon structures. Here, various synthesis processes of 3D porous carbon materials are summarized to understand how their physical and chemical properties together with heteroatom doping dictate the electrochemical catalytic performance. Prospects of attractive 3D carbon structural materials for energy conversion and efficient integrated energy systems are also discussed. 相似文献
128.
This article presents a novel framework for the multi-objective optimization of offshore renewable energy mooring systems using a random forest based surrogate model coupled to a genetic algorithm. This framework is demonstrated for the optimization of the mooring system for a floating offshore wind turbine highlighting how this approach can aid in the strategic design decision making for real-world problems faced by the offshore renewable energy sector. This framework utilizes validated numerical models of the mooring system to train a surrogate model, which leads to a computationally efficient optimization routine, allowing the search space to be more thoroughly searched. Minimizing both the cost and cumulative fatigue damage of the mooring system, this framework presents a range of optimal solutions characterizing how design changes impact the trade-off between these two competing objectives. 相似文献
129.
Jae‐Bok Lee Yi Rang Lim Ajit K. Katiyar Wooseok Song Jongsun Lim Sukang Bae Tae‐Wook Kim Seoung‐Ki Lee Jong‐Hyun Ahn 《Advanced materials (Deerfield Beach, Fla.)》2019,31(43)
Functional van der Waals heterojunctions of transition metal dichalcogenides are emerging as a potential candidate for the basis of next‐generation logic devices and optoelectronics. However, the complexity of synthesis processes so far has delayed the successful integration of the heterostructure device array within a large scale, which is necessary for practical applications. Here, a direct synthesis method is introduced to fabricate an array of self‐assembled WSe2/MoS2 heterostructures through facile solution‐based directional precipitation. By manipulating the internal convection flow (i.e., Marangoni flow) of the solution, the WSe2 wires are selectively stacked over the MoS2 wires at a specific angle, which enables the formation of parallel‐ and cross‐aligned heterostructures. The realized WSe2/MoS2‐based p–n heterojunction shows not only high rectification (ideality factor: 1.18) but also promising optoelectrical properties with a high responsivity of 5.39 A W?1 and response speed of 16 µs. As a feasible application, a WSe2/MoS2‐based photodiode array (10 × 10) is demonstrated, which proves that the photosensing system can detect the position and intensity of an external light source. The solution‐based growth of hierarchical structures with various alignments could offer a method for the further development of large‐area electronic and optoelectronic applications. 相似文献
130.
Woong‐Sig Moon Jae Chul Kim Kyoo‐Hyun Chung Eun‐Soo Park Mal‐Nam Kim Jin‐San Yoon 《应用聚合物科学杂志》2003,90(7):1797-1801
An acryl monomer containing the quinolone moiety was synthesized and then polymerized with azobisisobutyronitrile in a dimethylformamide solution. The resulting polymer as well as the corresponding monomer exhibited an excellent antibacterial activity. The poly(acrylated quinolone) (PQ) was compounded with other ordinary synthetic polymers such as low‐density polyethylene (LDPE), poly(butylene succinate) (PBS), poly(methyl methacrylate) (PMMA), maleated polypropylene (PPMA), and polycaprolactone (PCL). The polymer blends reduced the viable cell number significantly on contact during the shake flask test even when the PQ content was as low as 1 wt %. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1797–1801, 2003 相似文献