Near field enhancement in silver nanoantenna-superlens systems

We demonstrate near field enhancement generation in silver nanoantenna-superlens systems via numerical modeling. Using near-field interference and global optimization algorithms, we can design nanoantenna-superlens systems with mismatched permittivities, whose performance can match those with matched permittivities. The systems studied here may find broad applications in the fields of sensing, such as field-enhanced fluorescence and surface-enhanced Raman scattering, and the methodology used here can be applied to the designing and optimization of other devices, such as two-dimensional near field focusing lens. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4732793

Large-eddy-simulation of 3-dimensional Rayleigh-Taylor instability in incompressible fluids

The 3-dimensional incompressible Rayleigh-Taylor instability is numerically studied through the large-eddy-simulation (LES) approach based on the passive scalar transport model. Both the instantaneous velocity and the passive scalar fields excited by sinusoidal perturbation and random perturbation are simulated. A full treatment of the whole evolution process of the instability is addressed. To verify the reliability of the LES code, the averaged turbulent energy as well as the flux of passive scalar are calculated at both the resolved scale and the subgrid scale. Our results show good agreement with the experimental and other numerical work. The LES method has proved to be an effective approach to the Rayleigh-Taylor instability

Monitoring system of suspension type single hydraulic prop for underground forepoling

A monitoring system of suspension type single hydraulic prop for underground forepoling was introduced, and working principle and design scheme of the system were focused on. The system can realize pressure and bending deformation detection of hydraulic prop, LED warning and wireless data transmission. The experimental result based on a type of hydraulic prop shows that the error between measurement value of the system and the theoretical one is small, which verifies that the system can actually reflect bending deformation degree of suspension type single hydraulic prop when the hydraulic prop suffers different stress from roof and provide accurate data for safety warning of forepoling

Pollutant dispersion in built environment

This book discusses energy transfer, fluid flow and pollution in built environments. It provides a comprehensive overview of the highly detailed fundamental theories as well as the technologies used and the application of heat and mass transfer and fluid flow in built environments, with a focus on the mathematical models and computational and experimental methods. It is a valuable resource for researchers in the fields of buildings and environment, heat transfer and global warming

A combined framework of integrating optimized half-open spaces into buildings and an application to a realistic case study on urban ventilation and air pollutant dispersion

The project planning activities of urban air quality and breathability have increasingly become the noticed issues around the world in recent times. In this study, the incorporation of half-open spaces into the ground corners of high-rise buildings is accomplished by slightly modifying the building morphology as a feasible solution. A unified procedure is proposed via a combined framework of parametric CFD study and multivariable regression analysis to optimize the half-open space design for improving ventilation performance and air quality. The influences of four design parameters on wind flow characteristics are investigated, including (i) the building height, (ii) the width of street canyon, (iii) the height of half-open space, and (iv) the width of half-open space. Using the results from this combined framework, CFD simulations are then extended to inspect the effectiveness of merging optimized half-open space layouts into high-rise buildings as the deterministic analysis in a realistic case study. Both CFD simulations are validated with the wind tunnel data for a generic urban array and on-site measurements for a realistic case study. The predictions are discussed to evaluate the outcomes of urban breathability and air pollutant dispersion by the indices of air change per hour (ACH) and purging flow rate (PFR). The incorporation of optimized half-open spaces into constructions can greatly improve urban ventilation and air pollutant dispersion in the pedestrian pathway layer. To complete the combined framework for a realistic high-rise urban area, the optimized half-open space design can increase ACH* and PFR by 75% and 57%, respectively, in the pedestrian pathway layer, as compared to the case of original half-open space design. This strategy relies on the database formulated from the CFD results of varied building morphologies in the generic urban array to realize the optimized design in a more effective and time-saving manner when applying to realistic cases

Meticulous Land Cover Classification of High-Resolution Images Based on Interval Type-2 Fuzzy Neural Network with Gaussian Regression Model

This paper proposes a land cover classification method that combines a Gaussian regression model (GRM) with an interval type-2 fuzzy neural network (IT2FNN) model as a classification decision model. Problems such as the increase in the complexity of ground cover, the increase in the heterogeneity of homogeneous regions, and the increase in the difficulty of classification due to the increase in similarity in different regions are overcome. Firstly, the local spatial information between adjacent pixels was introduced into the Gaussian model in image gray space to construct the GRM. Then, the GRM was used as the base model to construct the interval binary fuzzy membership function model and characterize the uncertainty of the classification caused by meticulous land cover data. Thirdly, the upper and lower boundaries of the membership degree of the training samples in all categories and the principle membership degree as input were used to build the IT2FNN model. Finally, in the membership space, the neighborhood relationship was processed again to further overcome the classification difficulties caused by the increased complexity of spatial information to achieve a classification decision. The classical method and proposed method were used to conduct qualitative and quantitative experiments on synthetic and real images of coastal areas, suburban areas, urban areas, and agricultural areas. Compared with the method considering only one spatial neighborhood relationship and the classical classification method without a classification decision model, for images with relatively simple spatial information, the accuracy of the interval type-2 fuzzy neural network Gaussian regression model (IT2FNN_GRM) was improved by 1.3% and 8%, respectively. For images with complex spatial information, the accuracy of the proposed method increased by 5.0% and 16%, respectively. The experimental results prove that the IT2FNN_GRM method effectively suppressed the influence of regional noise in land cover classification, with a fast running speed, high generalization ability, and high classification accuracy