Grouting is the most commonly used method to control water inrush in underground engineering. Traditional cement-based materials are easy dilute and hard coagulate under influence of large flow high-velocity inrush. To address these deficiencies, a new type polymer grouting material with an excellent expansion ratio was synthesised. The quickly absorbs has 1:300. composed superabsorbent (SAP), glycerol, ethanol. effects quality on rate were examined, best solid–liquid for slurry determined...

A dual-polarized 4×4 scanning phased array antenna with leaky-wave enhanced lenses operating at 28 GHz is presented. Such an can be used for point-to-point fifth-generation (5G) communications that require high gain, wide bandwidth (BW), and limited steering ranges. The proposed has a periodicity of two wavelengths, the resulting grating lobes are suppressed by directive steerable element patterns. To achieve low-cost low-profile solution, feeds designed in printed circuit board made...

Drude's description of the response low-temperature gallium arsenide to optical pulse excitation is used evaluate components a time-domain Norton equivalent circuit photoconductive antenna (PCA) source. The saturation terahertz (THz) radiated power occurring at large levels was previously associated by scientific community radiation and charge screening bias. With present circuit, we are able model accurately measured as only due EM feedback from predicted THz shown match very measurements...

Quasi-optical (QO) antennas employ feeds in combination with lenses or reflectors. Design optimization of such can be expensive due to the high computational cost associated analysis electrically large and multiscale structures. This issue's "EM Programmer's Notebook" column describes a freely available MATLAB-based tool for fast QO antennas. It facilitates design antenna through introduction field-matching methodology. could also useful codesign components. The provides valuable...

State-of-the-art THz pulsed commercial systems operating over large bandwidth suffer from high dispersion or low radiation efficiency due to the poor coupling between transmitter and receiver photoconductive antennas (PCAs). In this work, we present fabrication characterization of a leaky-lens PCA that has potential solve problem. The presented is based on low-temperature grown gallium arsenide (LT-GaAs) membrane with 1:15 coverage (0.1–1.5 THz), where frequency response constant. order...

Large format focal plane arrays (FPAs) of dielectric lenses are promising candidates for wide field-of-view sub-millimeter imagers. In this work, we optimize the scanning gain such imagers via shaping lens surfaces. We develop an optimization procedure using a field correlation technique between fields generated by reflector on top and those feeds. Based procedure, FPA quartz antennas combined with leaky-wave feeds is designed to efficiently illuminate reflector, achieving directivity 50.5...

<title>Abstract</title> To solve the problem of environmental pollution from stockpiling solid waste and to achieve safe efficient underground engineering, an environment-friendly waste-based ternary geopolymer grout was developed using BFS, SSA, BRHA. KOH-activated grouts were used as controls. The applicability with different SSA additions also investigated. results showed that 28-day compressive strength SSA-activated reached 24.31 MPa, which exceeded control group by 163.7%. Potassium...

Photoconductive antennas (PCAs) are promising candidates for sensing and imaging applications. In recent years, our group has investigated their properties under pulsed laser illumination in transmission using a time-domain (TD) Norton equivalent circuit. Here we extend this analysis to the link between PC source receiver introducing latter second TD We also evaluate transfer function of dispersive quasi-optical (QO) link. Specifically, field correlation approach based on high-frequency...

Photoconductive antennas (PCAs) are promising candidates for sensing and imaging systems. We have investigated their properties under pulsed laser illumination both in transmission reception. First, a transmitting PCA has been characterized including power measurement. Then, Quasi-Optical (QO) link between transmitter receiver was modelled analyzed. In this work, we characterize with use bow-tie based PCAs as examples, measure the radiated of detected current receiver. The measurement shows...

Photoconductive antennas (PCA) are promising candidates for high-resolution imaging applications. They have been investigated in transmission when the receiver is a power detector. Here we consider another PCA as and develop model of quasi-optical (QO) coupling between transmitter under pulsed laser illumination. Specifically, field matching technique used to evaluate open-circuit voltage receiver. Based on this voltage, spectral mutual two PCAs, including QO path can be evaluated. A bow-tie...

Lens based focal plane arrays (FPAs) with thousand elements are promising candidates for wide scanning sub-millimeter security imaging systems. To analyze such arrays, a field correlation approach is employed to design an FPA of quartz lenses coupled reflector. We consider as the lens material due its lower cost compared silicon lenses. Here we focus on element at edge FPA. The reflector's angle 20.3°, and surface shaped couple better far-field performance optimized validated by full-wave...

A focal plane array of extended-hemispherical silicon lenses coupled to aluminum coplanar-waveguide (CPW) Microwave Kinetic Inductance Detectors (MKIDs) has been designed operate at 7.8 THz. Low-dispersive leaky-wave radiation used efficiently illuminate the antireflection-coated lenses. To minimize loss from antenna feeding lines these high frequencies, CPWs have miniaturized and placed on a dielectric membrane. test device fabricated its experimental characterization in terms sensitivity,...

Large format focal plane arrays (FPAs) of lenses are promising candidates for wide field view sub-millimeter imagers. Recently, a spectral technique based on coherent Fourier Optics has been proposed analyzing such lens FPAs in reception to facilitate the optimization via matching with feed pattern. Based this technique, three practical antenna geometries silicon, quartz and plastic combined leaky-wave feeds compared here. The synthesized achieved scan loss lower than standard horn FPAs,...

The time evolution of voltages and currents in a pulsed photo conductive antenna (PCA) source is evaluated resorting to rigorous procedure that stems from semiconductor physics first, define the phenomena involved generation photocurrent, then relies on an equivalent circuit domain, providing direct estimation power generated by PCA as well its spectral distribution. model validated via campaign measurements standard PC sources. saturation THz radiated occurring at large optical excitation...