79 research outputs found
Herding Effect based Attention for Personalized Time-Sync Video Recommendation
Time-sync comment (TSC) is a new form of user-interaction review associated
with real-time video contents, which contains a user's preferences for videos
and therefore well suited as the data source for video recommendations.
However, existing review-based recommendation methods ignore the
context-dependent (generated by user-interaction), real-time, and
time-sensitive properties of TSC data. To bridge the above gaps, in this paper,
we use video images and users' TSCs to design an Image-Text Fusion model with a
novel Herding Effect Attention mechanism (called ITF-HEA), which can predict
users' favorite videos with model-based collaborative filtering. Specifically,
in the HEA mechanism, we weight the context information based on the semantic
similarities and time intervals between each TSC and its context, thereby
considering influences of the herding effect in the model. Experiments show
that ITF-HEA is on average 3.78\% higher than the state-of-the-art method upon
F1-score in baselines.Comment: ACCEPTED for ORAL presentation at IEEE ICME 201
Phase transitions and topological properties of the 5/2 quantum Hall states with strong Landau-level mixing
We numerically study a 5/2 fractional quantum Hall system with even number of
electrons using the exact diagonalization where both the strong Landau level
(LL) mixing and a finite width of the quantum well have been considered and
adapted into a screened Coulomb interaction. With the principal component
analysis, we are able to recognize a compressible-incompressible phase
transition in the parameter space made of the magnetic field and the quantum
well width by the competition between the first two leading components of the
ground states wave functions, which is consistent with the low-lying spectral
feature and previous works in the odd-electron system. In addition, the
presence of the subdominant third component suggests an incompressible
transition occurring as the LL-mixing strength grows into a certain parameter
region associated with the ZnO experiments. We further investigate the strongly
LL-mixed phase in this emerging region with the Hall viscosity, wave function
overlaps, and the entanglement spectra. Results show it can be well described
as a particle-hole symmetrized Pfaffian state with the dual topological
properties of the Pfaffian and the anti-Pfaffian states
Facile Preparation of Bimetallic MOF-derived Supported Tungstophosphoric Acid Composites for Biodiesel Production
In this work, the novel TPA@C-NiZr-MOF catalyst is synthesized by the impregnation of tungstophosphoric acid (TPA) on the NiZr-based metal-organic framework (NiZr-MOF) followed by calcination up to 300 °C. The as-prepared catalyst materials were structurally, morphologically, and texturally characterized by XRD, FTIR, temperature programmed desorption of NH3 ( TPD-NH3 ), N2 physisorption, SEM, TEM, and XPS. The prepared catalyst can be used as an efficient heterogeneous catalyst for biodiesel production from oleic acid (OA) with methanol. The results indicated that, in comparison to TPA@NiZr-MOF, the TPA@C-NiZr-MOF catalyst calcined at 300 °C exhibits excellent catalytic performance probably owing to the synergistic effect between TPA and metal oxide skeletons, high acidity, as well as larger surface area and pore size. Additionally, the TPA@C-NiZr-MOF catalyst can be reused in up to six cycles with an acceptable conversion. This study showed that the bimetallic MOF-derived composite materials can be used as an alternative potential heterogeneous catalyst toward biorefinery applications
Quantum Multicritical Behavior for Coupled Optical Cavities with Driven Laser Fields
Quantum phase transitions with multicritical points are fascinating phenomena
occurring in interacting quantum many-body systems. However, multicritical
points predicted by theory have been rarely verified experimentally; finding
multicritical points with specific behaviors and realizing their control
remains a challenging topic. Here, we propose a system that a quantized light
field interacts with a two-level atomic ensemble coupled by microwave fields in
optical cavities, which is described by a generalized Dicke model.
Multicritical points for the superradiant quantum phase transition are shown to
occur. We determine the number and position of these critical points and
demonstrate that they can be effectively manipulated through the tuning of
system parameters. Particularly, we find that the quantum critical points can
evolve into a Lifshitz point if the Rabi frequency of the light field is
modulated periodically in time. Remarkably, the texture of atomic pseudo-spins
can be used to characterize the quantum critical behaviors of the system. The
magnetic orders of the three phases around the Lifshitz point, represented by
the atomic pseudo-spins, are similar to those of an axial
next-nearest-neighboring Ising model. The results reported here are beneficial
for unveiling intriguing physics of quantum phase transitions and pave the way
towards to find novel quantum multicritical phenomena based on the generalized
Dicke model
Immobilizing Ni (II)-Exchanged Heteropolyacids on Silica as Catalysts for Acid-Catalyzed Esterification Reactions
Biodiesel was synthesized from oleic acid using Ni (II)-exchanged heteropolyacids immobilized on silica (Ni0.5H3SiW / SiO2 ) as a solid acid catalyst. Based on detailed analyses of FT-IR, XRD, TG and SEM, the structural, surface and thermal stability of Ni0.5H3SiW / SiO2 were investigated. Obtained results demonstrated that the Keggin structure was well in the immobilization process and possess a high thermal stability. Various esterification reaction conditions and reusability of catalyst were studied. High oleic acid conversion of 81.4 % was observed at a 1:22 mole ratio (oleic acid: methanol), 3 wt. % catalyst at 70 °C for 4 h. The Ni0.5H3SiW / SiO2 catalyst was reused for several times and presented relatively stable. More interestingly, the kinetic studies revealed the esterification process was compatible with the first order model, and a lower activation energy was obtained in this catalytic system
Concurrent Modified Constant Modulus Algorithm and Decision Directed Scheme With Barzilai-Borwein Method
At present, in robot technology, remote control of robot is realized by wireless communication technology, and data anti-interference in wireless channel becomes a very important part. Any wireless communication system has an inherent multi-path propagation problem, which leads to the expansion of generated symbols on a time scale, resulting in symbol overlap and Inter-symbol Interference (ISI). ISI in the signal must be removed and the signal restores to its original state at the time of transmission or becomes as close to it as possible. Blind equalization is a popular equalization method for recovering transmitted symbols of superimposed noise without any pilot signal. In this work, we propose a concurrent modified constant modulus algorithm (MCMA) and the decision-directed scheme (DDS) with the Barzilai-Borwein (BB) method for the purpose of blind equalization of wireless communications systems (WCS). The BB method, which is two-step gradient method, has been widely employed to solve multidimensional unconstrained optimization problems. Considering the similarity of equalization process and optimization process, the proposed algorithm combines existing blind equalization algorithm and Barzilai-Borwein method, and concurrently operates a MCMA equalizer and a DD equalizer. After that, it modifies the DD equalizer's step size (SS) by the BB method. Theoretical investigation was involved and it demonstrated rapid convergence and improved equalization performance of the proposed algorithm compared with the original one. Additionally, the simulation results were consistent with the proposed technique
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