192 research outputs found
Negative to Positive Crossover of Magnetoresistance in Layered WS2 with Ohmic Contact
The discovery of graphene has ignited intensive investigation on two
dimensional (2D) materials. Among them, transition metal dichalcogenide (TMDC),
a typical representative, attracts much attention due to the excellent
performance in field effect transistor (FET) related measurements and
applications. Particularly, when TMDC eventually reaches few-layer dimension, a
wide range of electronic and optical properties, in striking contrast to bulk
samples, are detected. In this Letter, we synthesized single crystalline WS2
nanoflakes by physical vapor deposition (PVD) method and carried out a series
of transport measurements of contact resistance and magnetoresistance. Focused
ion beam (FIB) technology was applied to deposit Pt electrodes on WS2 flakes.
Different from the electron beam lithography (EBL) fabricated electrodes,
FIB-deposited leads exhibited ohmic contact, resolving the dilemma of Schottky
barrier. Furthermore, a temperature-modulated negative-to-positive transition
of magnetoresistance (MR) associated with a crossover of carrier type at
similar temperature was demonstrated. Our work offers a pathway to optimize the
contact for TMDC and reveals the magnetoresistance characteristics of WS2
flakes, which may stimulate further studies on TMDC and corresponding potential
electronic and optoelectronic applications
Research on Method of Health Assessment about the Destruction Equipment for High-risk Hazardous Chemical Waste
AbstractThe destroying tasks of high-risk hazardous chemical waste have a strict request to the health status of destruction equipment.The paper proposes the health status classification method based on time between failures for the destruction of equipment, set up health status assessment model based on Time-varying Bayesian Networks and the time slice, which can take advantage of history fault information and health status monitoring indicator information to health status assessment for the destruction equipment, and which provides a reliable and safe evaluation method
Fast and Resource-Efficient Object Tracking on Edge Devices: A Measurement Study
Object tracking is an important functionality of edge video analytic systems
and services. Multi-object tracking (MOT) detects the moving objects and tracks
their locations frame by frame as real scenes are being captured into a video.
However, it is well known that real time object tracking on the edge poses
critical technical challenges, especially with edge devices of heterogeneous
computing resources. This paper examines the performance issues and
edge-specific optimization opportunities for object tracking. We will show that
even the well trained and optimized MOT model may still suffer from random
frame dropping problems when edge devices have insufficient computation
resources. We present several edge specific performance optimization
strategies, collectively coined as EMO, to speed up the real time object
tracking, ranging from window-based optimization to similarity based
optimization. Extensive experiments on popular MOT benchmarks demonstrate that
our EMO approach is competitive with respect to the representative methods for
on-device object tracking techniques in terms of run-time performance and
tracking accuracy. EMO is released on Github at
https://github.com/git-disl/EMO
Hierarchical Pruning of Deep Ensembles with Focal Diversity
Deep neural network ensembles combine the wisdom of multiple deep neural
networks to improve the generalizability and robustness over individual
networks. It has gained increasing popularity to study deep ensemble techniques
in the deep learning community. Some mission-critical applications utilize a
large number of deep neural networks to form deep ensembles to achieve desired
accuracy and resilience, which introduces high time and space costs for
ensemble execution. However, it still remains a critical challenge whether a
small subset of the entire deep ensemble can achieve the same or better
generalizability and how to effectively identify these small deep ensembles for
improving the space and time efficiency of ensemble execution. This paper
presents a novel deep ensemble pruning approach, which can efficiently identify
smaller deep ensembles and provide higher ensemble accuracy than the entire
deep ensemble of a large number of member networks. Our hierarchical ensemble
pruning approach (HQ) leverages three novel ensemble pruning techniques. First,
we show that the focal diversity metrics can accurately capture the
complementary capacity of the member networks of an ensemble, which can guide
ensemble pruning. Second, we design a focal diversity based hierarchical
pruning approach, which will iteratively find high quality deep ensembles with
low cost and high accuracy. Third, we develop a focal diversity consensus
method to integrate multiple focal diversity metrics to refine ensemble pruning
results, where smaller deep ensembles can be effectively identified to offer
high accuracy, high robustness and high efficiency. Evaluated using popular
benchmark datasets, we demonstrate that the proposed hierarchical ensemble
pruning approach can effectively identify high quality deep ensembles with
better generalizability while being more time and space efficient in ensemble
decision making.Comment: To appear on ACM Transactions on Intelligent Systems and Technolog
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