32,590 research outputs found
Antibunching photons in a cavity coupled to an optomechanical system
We study the photon statistics of a cavity linearly coupled to an
optomechanical system via second order correlation functions. Our calculations
show that the cavity can exhibit strong photon antibunching even when
optomechanical interaction in the optomechanical system is weak. The
cooperation between the weak optomechanical interaction and the destructive
interference between different paths for two-photon excitation leads to the
efficient antibunching effect. Compared with the standard optomechanical
system, the coupling between a cavity and an optomechanical system provides a
method to relax the constraints to obtain single photon by optomechanical
interaction.Comment: 7 papes, 5 figure
Modeling the toroidal asymmetry of the heat load impacted by nitrogen injection in EAST using EMC3-EIRENE
Model the Relationship of NH3 Emission with Attributing Factors from Rice Fields in China: Ammonia Mitigation Potential Using a Urease Inhibitor
Substantial ammonia (NH3) losses from rice production result in poor nitrogen (N) use efficiency and environmental damage. A data synthesis using the published literature (127 studies
with 700 paired observations), combined with an incubation experiment using 50 paddy soils from across China, were conducted to improve the current understanding of the NH3 loss from paddy rice and its drivers. The efficacy of the urease inhibitor Limus® for reducing NH3 losses was also
evaluated. The mean loss of N, through NH3 volatilization, was 16.2% of the urea-N applied to paddy rice. The largest losses were from double rice cropping systems, and losses increased with the N application rate, surface application of N, unstable N types (ammonium bicarbonate and urea), and
high floodwater pH. Under simulated flooded conditions, urea amended with Limus® reduced NH3 loss by 36.6%, compared to urea alone, but floodwater pH had a significant effect on inhibitor efficacy. Key driving factors were air temperature, N application rate, and floodwater pH. The effectiveness
and limitations of the inhibitor in NH3 emission mitigation was examined, as well as its basis as one means of N pollution control in paddy rice cropping systems
Encapsulation of cesium with a solid waste-derived sulfoaluminate matrix: A circular economy approach of treating nuclear wastes with solid wastes
It is of great importance to safely dispose nuclear wastes with the development of nuclear industries. Past approaches to this problem have included immobilizing radioactive cesium in Portland cement-based matrices; however, the leaching rates of cesium are relatively high, especially as the leaching temperature increases. This paper explores a high-efficiency and cost-effective approach for encapsulating cesium using a sulfoaluminate cement (SAC) matrix, which was prepared via synergetic use of industrial solid wastes. Leaching results showed that, the apparent diffusion coefficient values of cesium were only ~1.4 × 10−15 cm2/s and ~5 × 10−18 cm2/s at 25 ℃ and 90 ℃ leaching conditions, respectively. These values were several orders of magnitude lower when compared with previously reported values, indicating the excellent encapsulation performance of the solid-waste-based SAC for cesium. Moreover, the heavy metals contained in the industrial solid waste were also effectively immobilized. A mechanistic analysis revealed that cesium was encapsulated in the SAC matrices stably by a physical effect. Finally, a life cycle assessment and economic analysis indicated that this approach was environmental-friendly, cost-effective, and energy-saving. This work provides a promising strategy for effective encapsulation of cesium and synergetic treatment of industrial solid wastes
Topological Electronic Structure and Its Temperature Evolution in Antiferromagnetic Topological Insulator MnBi2Te4
Topological quantum materials coupled with magnetism can provide a platform
for realizing rich exotic physical phenomena, including quantum anomalous Hall
effect, axion electrodynamics and Majorana fermions. However, these unusual
effects typically require extreme experimental conditions such as ultralow
temperature or sophisticate material growth and fabrication. Recently, new
intrinsic magnetic topological insulators were proposed in MnBi2Te4-family
compounds - on which rich topological effects could be realized under much
relaxed experimental conditions. However, despite the exciting progresses, the
detailed electronic structures observed in this family of compounds remain
controversial up to date. Here, combining the use of synchrotron and laser
light sources, we carried out comprehensive and high resolution angle-resolved
photoemission spectroscopy studies on MnBi2Te4, and clearly identified its
topological electronic structures including the characteristic gapless
topological surface states. In addition, the temperature evolution of the
energy bands clearly reveals their interplay with the magnetic phase transition
by showing interesting differences for the bulk and surface states,
respectively. The identification of the detailed electronic structures of
MnBi2Te4 will not only help understand its exotic properties, but also pave the
way for the design and realization of novel phenomena and applications.Comment: 18 pages, 4 figur
Knowledge-based recommendation with hierarchical collaborative embedding
© 2018, Springer International Publishing AG, part of Springer Nature. Data sparsity is a common issue in recommendation systems, particularly collaborative filtering. In real recommendation scenarios, user preferences are often quantitatively sparse because of the application nature. To address the issue, we proposed a knowledge graph-based semantic information enhancement mechanism to enrich the user preferences. Specifically, the proposed Hierarchical Collaborative Embedding (HCE) model leverages both network structure and text info embedded in knowledge bases to supplement traditional collaborative filtering. The HCE model jointly learns the latent representations from user preferences, linkages between items and knowledge base, as well as the semantic representations from knowledge base. Experiment results on GitHub dataset demonstrated that semantic information from knowledge base has been properly captured, resulting improved recommendation performance
Alfvenic Ion Temperature Gradient Activities in a Weak Magnetic Shear Plasma
We report the first experimental evidence of Alfvenic ion temperature
gradient (AITG) modes in HL-2A Ohmic plasmas. A group of oscillations with
kHz and is detected by various diagnostics in high-density
Ohmic regimes. They appear in the plasmas with peaked density profiles and weak
magnetic shear, which indicates that corresponding instabilities are excited by
pressure gradients. The time trace of the fluctuation spectrogram can be either
a frequency staircase, with different modes excited at different times or
multiple modes may simultaneously coexist. Theoretical analyses by the extended
generalized fishbone-like dispersion relation (GFLDR-E) reveal that mode
frequencies scale with ion diamagnetic drift frequency and , and they
lie in KBM-AITG-BAE frequency ranges. AITG modes are most unstable when the
magnetic shear is small in low pressure gradient regions. Numerical solutions
of the AITG/KBM equation also illuminate why AITG modes can be unstable for
weak shear and low pressure gradients. It is worth emphasizing that these
instabilities may be linked to the internal transport barrier (ITB) and H-mode
pedestal physics for weak magnetic shear.Comment: 9 pages, 7 figure
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