Tinghua Li

Diamond-shaped electromagnetic transparent devices with homogeneous material parameters

Based on the linear coordinate transformation method, two-dimensional and three-dimensional electromagnetic transparent devices with diamond shape composed of homogeneous and non-singular materials are proposed in this paper. The permittivity and permeability tensors of the transparent devices are derived. The performance and scattering properties of the transparent devices are confirmed by a full-wave simulation. It can physically protect electric devices such as an antenna and a radar station inside, without sacrificing their performance. This work represents important progress towards the practical realization of metamaterial-assisted transparent devices and expands the application of transformation optics.

Control system simulation of microgrid based on IP and Multi-Agent

Microgrid is a controllable unit integrated by distributed energy, load, energy storage and control devices. The operation and control of microgrid is the key to ensure the safety and stability of the power grid. In this paper, we design a microgrid monitor and control system based on IP and Multi-Agent, established by MATLAB and ZEUS platform. The bilateral switching between grid-connected mode and island mode is implemented by simulation. The results indicate the feasibility of multi-agent control system for microgrid control, operation and management.

Reciprocal Invisible Cloak with Homogeneous Metamaterials

Based on linear optical transformation method, a diamond shaped reciprocal cloak with perfect invisibility in a certain direction is proposed. Compared with traditional cloaks, the object hidden inside the reciprocal cloak is not blind and can receive information from the outer region. Moreover, the reciprocal cloak is constructed of nonsingular homogeneous material parameters with reduced anisotropy that is relatively easy for practical realization. Full wave simulations validate the performance of the cloak.

A pilot AMR system based on WIMAX and WSN

Nowadays wireless communication has become ubiquitous around the world and its application for gauging consumption of utilities by customers is rapidly gaining pace, not only in the developed world but also in the developing countries. In this paper, we propose a automatic meter reading (AMR) system which is a combination of wireless sensor network (WSN) and worldwide interoperability for microwave access (WiMAX) technology, and its feasibility and effectiveness are verified by the experiment in Yuxi city, Yunnan province, China. Results show that both A-C and A-B-D communication links have excellent link quality, and the success rates of meter reading are about 100%. The packet loss rates were close to zero, and the average delays were 32ms and 33ms, respectively, while 1000 packets were sent.

Three Dimensional Electromagnetic Concentrators with Homogeneous Material Parameters

By means of a three-step linear optical transformation method, material parameters of a three-dimensional diamond-shaped electromagnetic concentrator composed of tetrahedral homogeneous blocks has been derived in this paper. The performance of the concentrator has been confirmed by full-wave simulation. The designed concentrator can operate in a wide bandwidth due to the line transformation. It represents an important progress towards the practical realization of the metamaterial-assisted concentrator.

Homogeneous Material Constructed Acoustic Cloak Based on Coordinate Transformation

The two-dimensional and three-dimensional acoustic cloaks composed of homogeneous and nonsingular materials are designed by choosing appropriate spatial transformation. The mass density tensor and bulk modulus of the acoustic cloaks with diamond shape are derived, and extended to an acoustic carpet cloak. Performance of the acoustic cloaks is confirmed by full-wave simulation. The work represents an important progress towards the practical realization of the metamaterial-assisted acoustic cloak and expands the application of the coordinate transformation method.

A Microring Resonator Based Negative Permeability Metamaterial Sensor

Metamaterials are artificial multifunctional materials that acquire their material properties from their structure, rather than inheriting them directly from the materials they are composed of, and they may provide novel tools to significantly enhance the sensitivity and resolution of sensors. In this paper, we derive the dispersion relation of a cylindrical dielectric waveguide loaded on a negative permeability metamaterial (NPM) layer, and compute the resonant frequencies and electric field distribution of the corresponding Whispering-Gallery-Modes (WGMs). The theoretical resonant frequency and electric field distribution results are in good agreement with the full wave simulation results. We show that the NPM sensor based on a microring resonator possesses higher sensitivity than the traditional microring sensor since with the evanescent wave amplification and the increase of NPM layer thickness, the sensitivity will be greatly increased. This may open a door for designing sensors with specified sensitivity.

Graphene Assisted Radiation Adjustable OAM Generator

Graphene is increasingly being used in the design of electromagnetic devices. The resistivity of graphene can be adjusted via chemical potential tuning, which truly benefits the implementation of tunable and reconfigurable devices. This paper investigates the switch-like attribute of parasitic graphene surface used in a dipole operating at 0.39 THz. Further, a novel orbital angular moment (OAM) generator with radiation reconfiguration is proposed. Spiral beams carrying variety of OAM modes can be produced easily using the generator.

A pilot emergency communication system based on IP and airship

The problems facing the communication for emergency response were recently highlighted by frequent disasters. When stricken by a catastrophic natural or man-made disaster, terrestrial networks are severely destroyed, and satellite communication networks are deficient in bandwidth. Therefore, the communication systems are urgently needed in emergency response. In this paper, we extend the previous works about emergency communication for electric power system based on airship, and present a pilot emergency communication system based on IP and airship. The feasibility of the emergency communication system based on IP and airship are confirmed by experiment in Qujing City of Yunnan Province, China.

Diamond-shaped acoustic concentrator with homogeneous material parameters

Based on coordinate transformation method, the two-dimensional and three-dimensional acoustic concentrators with diamond shape composed of nonsingular homogeneous materials are designed in this paper. The mass density tensor and bulk modulus of the acoustic concentrators are derived. Performance of the concentrators is confirmed by full-wave simulation. The work represents an important progress towards the practical realization of the metamaterial-assisted acoustic concentrator and expands the application of the coordinate transformation method.