Fingerprint recognition is the most widely used identification method at present. However, it still falls short in terms of cross-platform and algorithmic complexity, which exerts a certain effect on the migration of fingerprint data and the development of the system. The conventional image recognition methods require offline standard databases constructed in advance for image access efficiency. The database can provide a pre-processed image via a specific method that probably is compatible merely with the specific recognition algorithm. Then, the specific recognition algorithm starts the process of retrieving these specific pre-proessing images for recognition and inevitably will be blocked from other datasets. The proposed method in this research designed an embedded image processing algorithm based on a Siamese neural network in the recognition method that allows the proposed method to recognize images from any source without constructing a database for image storage in advance. In this research, the proposed method was applied to fingerprint recognition and evaluation of the proposed method was evaluated. The results showed that the accuracy of the proposed algorithm was up to 92%, and its F1 score was up to 0.87. Compared with the conventional fingerprint matching methods, its significant advantage in the FRR, FAR, and CR jointly indicated the remarkable correct recognition rate of the proposed method.

The illusion device developed from the scattering cancellation employs very simple homogeneous and isotropic materials, but this device is only valid for electrically small objects. In this paper, we prove that the illusion device optimized by genetic algorithm can be applied to large-scale occasions. For an electrically small target, an optimized core-shell illusion device can achieve better illusion effect than the analytical design based on the scattering cancellation. With the increase of the device size, the ability of the single-layered shell to manipulate the scattering is very limited. For a moderate-size target, two optimized multi-layered examples are presented: one is to make a dielectric cylinder appear as another dielectric target, and the other is to make a conducting cylinder behave like a double-negative-material target. The full-wave simulations are carried out to visualize the similar field distributions of the target and the optimized multi-layered design. This optimized design greatly widens the size application range of the illusion device and can also improve the illusion performance with simple material parameters.

On the basis of transformation optics, we propose a view-field compressor for propagating beam fields. The device can compress the view field of 0 to 2π azimuthal angles into a given angle zone, for example π angle. We derive the required material of the compressor in the cylindrical coordinate system with anisotropic and inhomogeneous distribution of constitutive parameters. The functionality of the view-field compression is validated by full-wave electromagnetic simulations with several line sources located respectively in different azimuthal angles in the outer space. Moreover, when the radiation direction of a line source is restricted in some cases, for example sheltered by a perfect electric conducting (PEC) slab, this device can enlarge the beam directivity with omnidirectional performance.

The optimized cloaking design for conducting cylinders of different sizes is studied based on the Mie scattering theory. We construct a concentric multi-layered cloak made of alternating materials with isotropic dielectrics and epsilon-near-zero (ENZ) material, the thickness of which can be determined through genetic algorithm. As the radius of the conducting cylinder increases, high order scattering contributions are becoming evident, and more layers are needed. The scattering cross sections of three different radii of PEC cylinders are minimized by utilizing different numbers of multi-layers respectively. We find that eight or less optimized layers can cancel most of the scattering from a conducting cylinder with its dimension compared to wavelength, and more effectively when taking the ENZ material as the inner starting shell. The frequency dependence of total scattering is also studied, leading to the result that the bandwidth decreases as the size of concealed PEC cylinder increases. Furthermore, it is shown that the cloaking efficiency is less sensitive to the permittivity and thickness of the ENZ material, due to the small phase variation in the ENZ material. The multi-layered cloak designed for a PEC target can also be used to evidently reduce the scattering of a dielectric core and design a multi-layered elliptical cloak.

In this study, we demonstrate the design and fabrication of a tapered fiber sensor with a sensing application based on a new (high-sensitivity) package. We study the effect of various geometric parameters such as the uniform segment diameter, the uniform segment length, and the incident angle of the optical wave on the tapered fiber sensor sensitivity for evanescent sensing. Our study shows that high sensitivity of the tapered fiber can be realized by optimizing its parameters. In addition, we design a novel packaging of a tapered-fiber sensor, which can efficiently ensure a uniform stress and reduce the cross sensitivity caused by stress in liquid detection using a tapered fiber sensor. We report the experimental results obtained using this tapered fiber sensor for refractive-index measurements. As the refractive index of liquids varies from 1.417 to 1.423, the measurement results show that the refractive-index sensitivity of the tapered fiber sensor is as high as 4860 nm/RIU.

Reduction of electromagnetic scattering from a conducting cylinder could be achieved by covering it with optimized multilayers of normal dielectric and plasmonic material. The plasmonic material with intrinsic losses could degrade the cloaking effect. Using a genetic algorithm, we present the optimized design of loss and gain multilayers for reduction of the scattering from a perfect conducting cylinder. This multilayered structure is theoretically and numerically analyzed when the plasmonic material with low loss and high loss respectively is considered. We demonstrate by full-wave simulation that the optimized nonmagnetic gain-loss design can greatly compensate the decreased cloaking effect caused by loss material, which facilitates the realization of practical electromagnetic cloaking, especially in the optical range.

Virtual Reality technology is wild applied in various fields with its development. This article studied the application of virtual reality technology in green construction. On the discussion of the utility of desktop virtual reality system to accomplish the three-dimensional real-time simulation of green construction project, it shows that the application of virtual reality technology in the simulation of green construction not only reduces the construction cost but also breaks the limitation of time and space. The research of this paper has very high applied value.

Wireless sensor network (WSN) requires a wireless communication technology which is low in cost, low in power and easy to be implemented. IEEE802.15.4 standard is the standard specially designed for low-rate wireless personal area network (LR-WPAN) and aimed at introducing an unified standard for the low-rate interconnection between different devices used by a person or in a home, focusing on low power consumption, low-rate transmission and low cost. Since LR-WPAN which is defined on the basis of standard IEEE802.15.4 is of great similarity with WSN, it could be used as communication platform for wireless sensor. This paper, based on the analysis of LR-WPAN, puts forward the WSN networking scheme based on IEEE802.15.4.