1,266 research outputs found
Effect of a built-in electric field in asymmetric ferroelectric tunnel junctions
The contribution of a built-in electric field to ferroelectric phase
transition in asymmetric ferroelectric tunnel junctions is studied using a
multiscale thermodynamic model. It is demonstrated in details that there exists
a critical thickness at which an unusual ferroelectric-\'\' polar
non-ferroelectric\rq\rq phase transition occurs in asymmetric ferroelectric
tunnel junctions. In the \'\' polar non-ferroelectric\rq\rq phase, there is
only one non-switchable polarization which is caused by the competition between
the depolarizing field and the built-in field, and closure-like domains are
proposed to form to minimize the system energy. The transition temperature is
found to decrease monotonically as the ferroelectric barrier thickness is
decreased and the reduction becomes more significant for the thinner
ferroelectric layers. As a matter of fact, the built-in electric field does not
only result in smearing of phase transition but also forces the transition to
take place at a reduced temperature. Such findings may impose a fundamental
limit on the work temperature and thus should be further taken into account in
the future ferroelectric tunnel junction-type or ferroelectric capacitor-type
devices.Comment: 9 pages, 8 figures, submitted to PR
Self-Sustaining Caching Stations: Towards Cost-Effective 5G-Enabled Vehicular Networks
In this article, we investigate the cost-effective 5G-enabled vehicular
networks to support emerging vehicular applications, such as autonomous
driving, in-car infotainment and location-based road services. To this end,
self-sustaining caching stations (SCSs) are introduced to liberate on-road base
stations from the constraints of power lines and wired backhauls. Specifically,
the cache-enabled SCSs are powered by renewable energy and connected to core
networks through wireless backhauls, which can realize "drop-and-play"
deployment, green operation, and low-latency services. With SCSs integrated, a
5G-enabled heterogeneous vehicular networking architecture is further proposed,
where SCSs are deployed along roadside for traffic offloading while
conventional macro base stations (MBSs) provide ubiquitous coverage to
vehicles. In addition, a hierarchical network management framework is designed
to deal with high dynamics in vehicular traffic and renewable energy, where
content caching, energy management and traffic steering are jointly
investigated to optimize the service capability of SCSs with balanced power
demand and supply in different time scales. Case studies are provided to
illustrate SCS deployment and operation designs, and some open research issues
are also discussed.Comment: IEEE Communications Magazine, to appea
Supported ITZ modification efficiencies via surface coating nanoparticles on aggregate and its influence on properties
In order to modify the porous interfacial transition zone (ITZ) microstructure of concrete more efficiently, a method of coating aggregate surfaces by using several nanoparticles was evaluated in this study. The compressive strength, chloride penetration of sound, and pre-loading samples were assessed in relation to the type of coating materials used (slag, nano-CaCO3, and nano-SiO2) and the designed coating thickness (5, 10, and 15 mu m). The ITZ microstructure was quantitatively determined via Backscattered electron (BSE) image analysis. Results showed that the overall performance of concrete is highly dependent on the coating materials and the designed coating thickness. Increasing the coating thickness of slag and nano-SiO2 could improve the chloride penetration resistance but decrease the compressive strength. Using nano-CaCO3 to coat the aggregate leads to a significant reduction in the properties of the so-prepared concrete. Though coating inert fine particles around aggregate could disturb the initial particle packing and modify the ITZ, it is not able to improve the overall concrete properties. Coating aggregate could determine the ITZ microstructure, especially within the region that is around 30 mu m away from aggregate surface
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
How do tourism goal disclosure motivations drive Chinese tourists\u27 goal-directed behaviors? The influences of feedback valence, affective rumination, and emotional engagement
Based on self-determination theory and the broaden-and-build theory of positive emotion, this study investigated the motivations of disclosing tourism goals on social media and its impacts on Chinese tourists\u27 goal-directed behaviors (GDBs). We proposed and tested a mutual transformation model of tourism goal disclosure motivation under different conditions of feedback valence (positive vs. negative feedback) and examine the mediating role of tourists\u27 affective rumination and emotional engagement. The results revealed that tourists driven by extrinsic motivations develop a stronger emotional engagement in their tourism goals and exhibit more GDBs after receiving positive feedback on their disclosed tourism goals. However, negative feedback disclosed goals lowers GDBs and leads to affective rumination about tourism goals among those with intrinsic motivations. This study provides theoretical and practical implications for destination marketers to adopt marketing strategies based on the findings
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