284 research outputs found
Pyrolysing horse manure via microwave-induced heating for bioenergy recovery
Transforming waste to energy is essential in view of the need to search for greener and more sustainable energy sources. Such transformation of energy is also aligned with the aim of reducing excessive waste generation whilst creating potential biofuel pathways for power generation. In the present study, animal waste in the form of horse manure is being used as feedstock to undergo microwave-induced pyrolysis via a fixed-bed pyrolysis rig. The relationship of the pyrolysis parameters such as pyrolysis temperature of 350 and 550 °C, carrier gas flow rate of 0.5 and 1.5 L/min and ratio of horse manure to activated carbon blend of 1:2 and 1:1, with the yield of pyrolysed products is studied. The derived pyrolysis products in the form of solid, liquid and gaseous are characterised and quantified. Result shows that the highest yield of solid, liquid and gaseous products obtained are 78.8 wt%, 24.7 wt% and 34.2 wt%. Solid yield is observed to decrease with increasing pyrolysis temperature while gaseous yield shows a reverse trend. Higher carrier gas flow rate is observed to lower the generation of gaseous and liquid yield while increasing the solid yield. Higher amount of activated carbon within the feedstock is seen to lower the solid yield but increase the gaseous and liquid yields. The liquid yield is found to contain 55.78 wt% of phenolic compounds while gaseous product consists of up to 55 vol% of syngas. The control of the operating conditions in pyrolysis rig enables the production of pyrolysis end products in different phases, generating useful bioenergy and biofertilizer products in the context of circular economy
Fetal tracheolaryngeal airway obstruction: prenatal evaluation by sonography and MRI
We reviewed the sonographic and MRI findings of tracheolaryngeal obstruction in the fetus. Conditions that can cause tracheolaryngeal obstruction include extrinsic causes such as lymphatic malformation, cervical teratoma and vascular rings and intrinsic causes such as congenital high airway obstruction syndrome (CHAOS). Accurate distinction of these conditions by sonography or MRI can help facilitate parental counseling and management, including the decision to utilize the ex utero intrapartum treatment (EXIT) procedure
Observation of single collisionally cooled trapped ions in a buffer gas
Individual Ba ions are trapped in a gas-filled linear ion trap and observed
with a high signal-to-noise ratio by resonance fluorescence. Single-ion storage
times of ~5 min (~1 min) are achieved using He (Ar) as a buffer gas at
pressures in the range 8e-5 - 4e-3 torr. Trap dynamics in buffer gases are
experimentally studied in the simple case of single ions. In particular, the
cooling effects of light gases such as He and Ar and the destabilizing
properties of heavier gases such as Xe are studied. A simple model is offered
to explain the observed phenomenology.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. A. Minor
text and figure change
Spin-orbit density wave induced hidden topological order in URu2Si2
The conventional order parameters in quantum matters are often characterized
by 'spontaneous' broken symmetries. However, sometimes the broken symmetries
may blend with the invariant symmetries to lead to mysterious emergent phases.
The heavy fermion metal URu2Si2 is one such example, where the order parameter
responsible for a second-order phase transition at Th = 17.5 K has remained a
long-standing mystery. Here we propose via ab-initio calculation and effective
model that a novel spin-orbit density wave in the f-states is responsible for
the hidden-order phase in URu2Si2. The staggered spin-orbit order 'spontaneous'
breaks rotational, and translational symmetries while time-reversal symmetry
remains intact. Thus it is immune to pressure, but can be destroyed by magnetic
field even at T = 0 K, that means at a quantum critical point. We compute
topological index of the order parameter to show that the hidden order is
topologically invariant. Finally, some verifiable predictions are presented.Comment: (v2) Substantially modified from v1, more calculation and comparison
with experiments are include
Search for nucleon decays with EXO-200
A search for instability of nucleons bound in Xe nuclei is reported
with 223 kgyr exposure of Xe in the EXO-200 experiment. Lifetime
limits of 3.3 and 1.9 yrs are established for
nucleon decay to Sb and Te, respectively. These are the most
stringent to date, exceeding the prior decay limits by a factor of 9 and 7,
respectively
Deep Neural Networks for Energy and Position Reconstruction in EXO-200
We apply deep neural networks (DNN) to data from the EXO-200 experiment. In
the studied cases, the DNN is able to reconstruct the relevant parameters -
total energy and position - directly from raw digitized waveforms, with minimal
exceptions. For the first time, the developed algorithms are evaluated on real
detector calibration data. The accuracy of reconstruction either reaches or
exceeds what was achieved by the conventional approaches developed by EXO-200
over the course of the experiment. Most existing DNN approaches to event
reconstruction and classification in particle physics are trained on Monte
Carlo simulated events. Such algorithms are inherently limited by the accuracy
of the simulation. We describe a unique approach that, in an experiment such as
EXO-200, allows to successfully perform certain reconstruction and analysis
tasks by training the network on waveforms from experimental data, either
reducing or eliminating the reliance on the Monte Carlo.Comment: Accepted version. 33 pages, 28 figure
Search for Neutrinoless Double-Beta Decay in Xe with EXO-200
We report on a search for neutrinoless double-beta decay of Xe with
EXO-200. No signal is observed for an exposure of 32.5 kg-yr, with a background
of ~1.5 x 10^{-3} /(kg yr keV) in the region of interest. This
sets a lower limit on the half-life of the neutrinoless double-beta decay
(Xe) > 1.6 x 10 yr (90% CL),
corresponding to effective Majorana masses of less than 140-380 meV, depending
on the matrix element calculation
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