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Terahertz (THz) radiation has attracted a lot of attentions due to its fascinating potential applications. However, the traditional THz devices have relatively large size due to the long wavelength nature of the THz radiation. Several metasurface-based THz devices, including lens, computer generated holograms, spin selected focusing lens, as well as wavelength selected diffractive elements, have been...
This paper presents a fan-beam patch antenna array with low cross-polarization. The proposed antenna array consists of 13 sub-arrays and each array has 7 elements. The element distance in each array is equal, whereas the distances between the sub-arrays are designed to be different in order to decrease the radiation in the side lobe level. Narrower beam width and lower side lobe level can be realized...
Discriminating exo-atmosphere micro-motion targets is a key technology for precise guidance systems, infrared surveillance systems, and satellite remote sensing systems. Commonly, static IR images are insufficient to discriminate different targets in the field of view. The infrared signature, i.e., the time sequence of the target point's gray level in the infrared images serve as potential discriminants...
As an important passive sensing technology, infrared sensor has been used in satellite remote sensing systems to discriminate exo-atmosphere targets. At a long range, even relatively large objects are represented as single pixels on the IR image. The infrared signature, i.e., the time sequence of the target point's gray level serves as potential discriminants and has been used in many systems to classify...
High penetrations of distributed renewables can dramatically increase uncertainty in the transmission system, making small-signal stability verification far more challenging. In this paper, we examine the impact of generating 30% of the power in the IEEE 118 bus test network with 118 distributed renewable sources, and show the inadequacy of sampling approaches to stability analysis. We show that multipoint...
Accurate modelling of photovoltaic (PV) modules is necessary to understand PV cell operation and to develop maximum power point tracking (MPPT) algorithm for efficient operation of the PV system. A variety of models are proposed in the literature that use a current source, diodes and resistors to represent a PV module. The parameter values involved in the model need to be accurately estimated to improve...
A prompt and accurate bulk system islanding detection capability is essential for real-time operation to maintain system reliability. This paper introduces and proposes two islanding detection methods, “Frequency Standard Deviation” and “Relative Phase Angle Change Rate” based on PMU measurement. The detailed analysis and explanation of the approaches to the design of islanding scheme is provided...
Gas switch plays a key role in the pulsed power system. In this paper, we observed the discharge process of a particle beam triggered gas switch at the lowest working coefficient. The temporal and spatial evolution of particle beam was captured in real time and the velocity curves of particle beam under different gas pressures were obtained. And the triggering mechanism of the gas switch was analyzed...
A low profile, high gain and wideband parasitic patch antenna with filtering response is investigated in this paper. The parasitic patches are fed by two separated microstrip-coupled slots from the bottom. Good filtering performance in the lower stopband is achieved by the separation between the two slots together with a shorting via, whereas a sharp roll-off rate at upper band edge for the filtering...
Ground Penetrating Radar (GPR) is a well-received non-destructive technique for the detection of underground utilities, such as water/gas pipes, sewers, power cables, and telecommunication ducts. However, radar signatures of non-metallic pipes are generally weak in certain conditions, for instance when the surrounding soils are attenuative and/or the pipe-soils interface is non-distinguishable from...
The health status of a railway tunnel should be regularly inspected during its service period for safe operation. The frequency of periodic inspection should be increased when the tunnel has become aged. For the coverage tunnels, health assessment is more essential. Ground penetrating radar (GPR) has been used as a key tunnel health detecting technique; however, so far, such (GPR) techniques are in...
With the development of Ultra-Wideband (UWB) technology, UWB radar is widely used in disaster search and rescue operations and hostage rescue situations. Distinguishing between humans and animals is important during such searches. The aim of this paper is to study whether there are differences between humans and animals detected by UWB radar and whether these differences could be distinguished. In...
The uptake of high penetrations of renewable energy in microgrids is curtailed by concerns that their intermittency may cause the system to become unstable. The classic approach of small-signal stability analysis may lead to overly optimistic conclusions, because it implicitly assumes that the intermittency is small-signal in nature. Instead, LMI techniques from robust controls can be used to provide...
A single-longitudinal-mode Nd:YAG laser was demonstrated using a twisted-mode cavity and an etalon. Stable laser pulses at 10 kHz were obtained with a RTP electro-optic modulator. Under an incident pump power of 8.1 W, the maximum output power of the single-longitudinal-mode laser was 1.07 W, and the linewidth was less than 0.1 GHz.
A transient optical diagnostic system for studying the discharge characteristics of a particle beam triggered gas switch was built, so that the temporal and spatial evolution of particle beam was observed in real time and the velocity curves of particle beam under different gas pressures were obtained. And the discharge processes of two spark gaps were photoelectric diagnosed and analyzed respectively...
A switched nonlinear complex system is studied. It is assumed that the corresponding isolated subsystems are generalized homogeneous of positive orders. An approach to a hybrid comparison equation constructing for the considered system is proposed. Classes of admissible switching laws are determined for which one can guarantee asymptotic stability of the zero solution of the complex system or entering...
This paper presents an operation strategy for microgrids to provide inertial and frequency response using the kinetic energy stored in their induction motor (IM) loads. This is achieved by actively controlling the microgrid electrical frequency in systems that connect to the network through an asynchronous link. The strategy is demonstrated to provide an inertial response to disturbances inside a...
In this work, IGZO ink was prepared by dissolving gallium chloride, indium chloride, zinc acetate dihydrate and monoethanolamine (MEA) in 2-methoxyethanol. Five types of IGZO ink were prepared with different molar ratios of In:Ga:Zn: A(10:1:10), B(10:3:10), C(10:5:10), D(10:7:10), E(10:9:10). Based on the above-prepared ink, IGZO films were printed by a FujiFilm Dimatix printer (DMP-2831) on the glass,...
In this study, we used combinatorial pulsed laser deposition (PLD) method to deposit Ce:YIG thin films with high Ce concentration on silicon. Thin films with record high Ce concentrations of Ce1.3Y1.7Fe5O12 were successfully grown on silicon, which showed about 3 fold enhancement of the Kerr rotation at 635 nm wavelength compared to previously reported Ce1Y2Fe5O12. CexY3−xFe5O12 films with Ce concentration...
In this work, memory devices with Ag/a-IGZO/ITO structures were fabricated mainly based on solution-based synthesis approaches. Specifically, the IGZO thin film was prepared by spin coating of IGZO ink and the top Ag electrodes were formed by ink-jet printing. Electrical measurements showed that Roff/Ron ratio was over two orders and the device resistance and could be maintained up to 105s without...
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