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This report presents THz spectroscopy as a valuable tool to discover unique signatures in a variety of analytes. Biomolecules and bacterial spores have been demonstrated to have characteristic signatures in the absorption patterns. Examples presented are the absorption band of thymine and the double bands of Bacillus sp. spores. In the case of thymine, the absorption band exactly matched the results...
New materials, such as bottle caps and egg cartons can be used to build an echo-friendly acoustical room for increasing speech intelligibility and also for obtaining better conditions in multimedia studios. Unrecyclable bottle caps can play the role of scatterers. The reflection and absorption coefficients of bottle caps vary according to their diameters and position and thus have a great effect on...
In this paper, an ultra-thin LC resonator structure operating in X-band is designed which is intended to be used as a shield to reduce the radar cross section of a conducting plate. The proposed structure is simulated using Ansoft HFSS software which shows an absorption peak at 8.125 GHz with reflection coefficient of -34.2 dB. The LC structure constructed from resistive/low conductivity material...
We probe porous metal-organic framework materials (MOFs) using broadband terahertz (THz) pulses. Water molecules that are absorbed by the pores of the material display intermolecular dynamics differing from those of free water.
We design a novel core-shell nanocone structure that allows full absorption of sunlight in an iron oxide photoanode. The photocurrent approaches 12.5mA/cm2 within an iron oxide thickness of 20nm, verified by full-field electromagnetic simulation.
We measured the current-voltage and infrared optical transmission characteristics of thin film VO2 wires over the metal-insulator phase transition. The phase transition had electrical or thermal characteristics depending on the wire geometry and applied current.
We use titanium nitride (TiN) to demonstrate an ultra-thin plasmonic thermal emitter operating at high temperatures (830 K). The spectrally selective emitter exhibits a large emittance at around 2.5 µm and below, and suppresses emission at longer wavelengths.
Absorption coefficient of erbium chloride silicate nanowire is studied by monitoring the decay of upconversion emission from a single nanowire waveguide. 30 dB/cm low bound for the net gain is demonstrated for erbium chloride silicate.
We have developed a pump-probe configuration to measure the carrier lifetime using the transient free-carrier density. The free-carrier absorption varies as λ2 Δn/μ, where λ is 10.6 µm in this paper. We measure the transient photoconductive decay that is proportional to Δn * μ. The data product gives Δβ * Δσ∼ λ2Δn(t)2. The mobility variation is nullified by multiplying the data from the two parallel...
The limiting efficiency for photovoltaic energy conversion based on a semiconductor pn-junction is typically determined using the method of detailed balance put forth by Shockley and Queisser. Here we describe how this theory is altered in the presence of a photonic structure that is capable of modifying the absorption and emission of photons. By incorporating specifically designed photonic structures,...
This study was conducted to determine the potential of office paper waste and rice husk as acoustic cell material as an absorbent noise. The acoustic cell material combines waste paper and rice husk are given a binder of PVA (polyvinyl acetate). Studies conducted with specimens of making destroy paper then mixed with rice husk. Previous chemically treated rice husks with alkali method governed by...
Infrared has been widely used in many engineering applications especially in medical devices. For example, in biomedical engineering, infrared based sensors are used to detect and measure human body composition such as water content, fat percentage and muscle mass. Infrared based sensors are popular as it enables a fast and non-destructive method to detect fat content and water in food items. Many...
In a high humidity environment, the composite insulating material will absorb moisture from the air, the dielectric properties of the material may change consequently, thus accelerating degradation of mechanical and insulating properties. High-temperature vulcanized (HTV) silicone rubber, commonly used as composite insulators shed and housing materials, has been investigated for their moisture absorption...
A heterogeneous THz-QCL is used for diffuse-reflectance imaging of powdered solids at 4 frequencies in the range 3.05–3.35 THz. An effective-optical-path-length model reproduces TDS absorption spectra accurately and discriminates between admixtures of materials with differing concentrations.
The dynamic non-linear material response of graphene is introduced into finite-difference time-domain simulations using a carrier rate equation. Experimental measurements of grapheme's relaxation time and saturation intensity are used to demonstrate sub-picosecond pulse formation via passive mode-locking in a 95 μm long Bragg cavity.
Single-crystalline sodium tungsten bronze (Na-WO3) nanorods with typical diameters of 10–200 nm and lengths of several of microns were prepared via hydrothermal synthesis. X-ray diffraction data showed that the as-prepared Na-WO3 nanorods crystallize in a hexagonal structure (space group P6 / mmm) with unit cell parameters a = 7.3166(8) Å and c = 3.8990(8) Å, and elongate along the <001> direction...
‘Acoustic black holes’ are relatively new physical objects that have been introduced and investigated mainly during the last decade. They can absorb almost 100% of the incident wave energy, which makes them attractive for such traditional engineering applications as vibration damping and sound absorption. They could be useful also for some ultrasonic devices using Lamb waves to provide anechoic termination...
The possibility to design ultra-thin absorbers within ultra-high frequency range by employing low-cost materials is investigated. The proposed materials would be particularly useful to improve the reading performance of RFID readers in complex environments.
In this paper we predict how a valence band excitation couples with TE-polarized THz radiation in a microcavity. This configuration would allow easier measurements of polaritons and antipolaritons without the need to grow the resonator in a slanted prism, as in usual TM mode, conduction band realizations.
Energy released by electric arc during short circuit switching is mostly absorbed by the surrounding cold SF6 gas. However, a considerable part of this energy is also transferred and absorbed by other elements of the circuit breaker interrupter which are located near the electric arc. The most important parts are the transfer of energy to the arcing contacts and to the nozzles, absorption of the energy...
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