232 research outputs found
Microwave whirlpools in a rectangular-waveguide cavity with a thin ferrite disk
We study a three dimensional system of a rectangular-waveguide resonator with
an inserted thin ferrite disk. The interplay of reflection and transmission at
the disk interfaces together with material gyrotropy effect, gives rise to a
rich variety of wave phenomena. We analyze the wave propagation based on full
Maxwell-equation numerical solutions of the problem. We show that the
power-flow lines of the microwave-cavity field interacting with a ferrite disk,
in the proximity of its ferromagnetic resonance, form whirlpool-like
electromagnetic vortices. Such vortices are characterized by the dynamical
symmetry breaking. The role of ohmic losses in waveguide walls and dielectric
and magnetic losses in a disk is a subject of our investigations
Recommended from our members
A Bouquet of Wisdom and Invective: Houghton MS. Lat 300
The Classic
Recommended from our members
Tito Vespasiano Strozzi's "Ad psyttacum": A Renaissance Latin Poet Parrots the Past
The Classic
Abnormal phenomena in a one-dimensional periodic structure containing left-handed materials
The explicit dispersion equation for a one-dimensional periodic structure
with alternative layers of left-handed material (LHM) and right-handed material
(RHM) is given and analyzed. Some abnormal phenomena such as spurious modes
with complex frequencies, discrete modes and photon tunnelling modes are
observed in the band structure. The existence of spurious modes with complex
frequencies is a common problem in the calculation of the band structure for
such a photonic crystal. Physical explanation and significance are given for
the discrete modes (with real values of wave number) and photon tunnelling
propagation modes (with imaginary wave numbers in a limited region).Comment: 10 pages, 4 figure
Aduroidbased planar EBG cavity resonator filter with improved quality factor
Abstract-A high- Duroid-based planar electromagnetic bandgap (EBG) cavity resonator/filter has been designed, fabricated, and tested. It was implemented in Rogers Duroid 5880 with standard board fabrication techniques. This filter provides a measured of 844 and a 0.91% bandwidth passband response at 10.63 GHz with a corresponding insertion loss of 2.76 dB
Monitoring and validating the transport of waste
The illegal disposal of waste is a growing problem in many countries of the Organization for Economic Cooperation and Development. A weakness with the conventional waste- management cycle concerns the validation and integrity of the transportation process, from collection at industrial premises to delivery at a licenced waste-disposal facility. The on-going Waste Augmentation and Integrated Shipment Tracking (Waist) project, at CLARITY: Centre for Sensor Web Technologies, focuses on this very problem. Waist integrates a triptych of sensing technologies in addressing this problem
The benzene polycarboxylic acid (BPCA) pattern of wood pyrolyzed between 200°C and 1000°C
Environmental charcoals represent a poorly defined part of the black carbon (BC) combustion continuum and may differ widely in their chemical and physical properties, depending on combustion conditions and source material. The benzene polycarboxylic acid (BPCA) molecular marker method is well established to quantify the BC component in charcoal, soil and sediment, although observed variations between labs could stem from subtle differences in methods. The objectives of this study were to identify and improve potential sources of analytical uncertainty. The improved method was then used to qualitatively characterize wood charred at 200–1000 °C. One significant improvement of the BPCA method was to replace citric acid with phthalic acid as an internal standard, which is more stable in acidic solution and more similar to the target compounds. Also, including a soil reference material as a quality control in each analysis proved to be a robust tool to detect for variations in reproducibility. For the thermosequence, elemental O/C and H/C ratios typically decreased with temperature to 60.03 at 1000 °C, whereas BPCA concentrations peaked at 700 °C. With temperature B6CA proportions increased consistently (6–98%), except for a plateau at 250–500 °C. Thus, relative contributions of B6CA reflected the pyrolysis temperature and probably also the degree of condensation of the charcoals we investigated. Future work will show if our results can be directly related to charcoal produced under oxygen limited conditions, including charcoal formed at wildfires or so called biochar for agricultural use
- …