589 research outputs found
An efficient surrogate model for emulation and physics extraction of large eddy simulations
In the quest for advanced propulsion and power-generation systems,
high-fidelity simulations are too computationally expensive to survey the
desired design space, and a new design methodology is needed that combines
engineering physics, computer simulations and statistical modeling. In this
paper, we propose a new surrogate model that provides efficient prediction and
uncertainty quantification of turbulent flows in swirl injectors with varying
geometries, devices commonly used in many engineering applications. The novelty
of the proposed method lies in the incorporation of known physical properties
of the fluid flow as {simplifying assumptions} for the statistical model. In
view of the massive simulation data at hand, which is on the order of hundreds
of gigabytes, these assumptions allow for accurate flow predictions in around
an hour of computation time. To contrast, existing flow emulators which forgo
such simplications may require more computation time for training and
prediction than is needed for conducting the simulation itself. Moreover, by
accounting for coupling mechanisms between flow variables, the proposed model
can jointly reduce prediction uncertainty and extract useful flow physics,
which can then be used to guide further investigations.Comment: Submitted to JASA A&C
GAMIVAL: Video Quality Prediction on Mobile Cloud Gaming Content
The mobile cloud gaming industry has been rapidly growing over the last
decade. When streaming gaming videos are transmitted to customers' client
devices from cloud servers, algorithms that can monitor distorted video quality
without having any reference video available are desirable tools. However,
creating No-Reference Video Quality Assessment (NR VQA) models that can
accurately predict the quality of streaming gaming videos rendered by computer
graphics engines is a challenging problem, since gaming content generally
differs statistically from naturalistic videos, often lacks detail, and
contains many smooth regions. Until recently, the problem has been further
complicated by the lack of adequate subjective quality databases of mobile
gaming content. We have created a new gaming-specific NR VQA model called the
Gaming Video Quality Evaluator (GAMIVAL), which combines and leverages the
advantages of spatial and temporal gaming distorted scene statistics models, a
neural noise model, and deep semantic features. Using a support vector
regression (SVR) as a regressor, GAMIVAL achieves superior performance on the
new LIVE-Meta Mobile Cloud Gaming (LIVE-Meta MCG) video quality database.Comment: Accepted to IEEE SPL 2023. The implementation of GAMIVAL has been
made available online: https://github.com/lskdream/GAMIVA
Study of Subjective and Objective Quality Assessment of Mobile Cloud Gaming Videos
We present the outcomes of a recent large-scale subjective study of Mobile
Cloud Gaming Video Quality Assessment (MCG-VQA) on a diverse set of gaming
videos. Rapid advancements in cloud services, faster video encoding
technologies, and increased access to high-speed, low-latency wireless internet
have all contributed to the exponential growth of the Mobile Cloud Gaming
industry. Consequently, the development of methods to assess the quality of
real-time video feeds to end-users of cloud gaming platforms has become
increasingly important. However, due to the lack of a large-scale public Mobile
Cloud Gaming Video dataset containing a diverse set of distorted videos with
corresponding subjective scores, there has been limited work on the development
of MCG-VQA models. Towards accelerating progress towards these goals, we
created a new dataset, named the LIVE-Meta Mobile Cloud Gaming (LIVE-Meta-MCG)
video quality database, composed of 600 landscape and portrait gaming videos,
on which we collected 14,400 subjective quality ratings from an in-lab
subjective study. Additionally, to demonstrate the usefulness of the new
resource, we benchmarked multiple state-of-the-art VQA algorithms on the
database. The new database will be made publicly available on our website:
\url{https://live.ece.utexas.edu/research/LIVE-Meta-Mobile-Cloud-Gaming/index.html}Comment: Accepted to IEEE Transactions on Image Processing, 2023. The database
will be publicly available by 1st week of July 202
The bracteatus pineapple genome and domestication of clonally propagated crops
Domestication of clonally propagated crops such as pineapple from South America was hypothesized to be a 'one-step operation'. We sequenced the genome of Ananas comosus var. bracteatus CB5 and assembled 513 Mb into 25 chromosomes with 29,412 genes. Comparison of the genomes of CB5, F153 and MD2 elucidated the genomic basis of fiber production, color formation, sugar accumulation and fruit maturation. We also resequenced 89 Ananas genomes. Cultivars 'Smooth Cayenne' and 'Queen' exhibited ancient and recent admixture, while 'Singapore Spanish' supported a one-step operation of domestication. We identified 25 selective sweeps, including a strong sweep containing a pair of tandemly duplicated bromelain inhibitors. Four candidate genes for self-incompatibility were linked in F153, but were not functional in self-compatible CB5. Our findings support the coexistence of sexual recombination and a one-step operation in the domestication of clonally propagated crops. This work guides the exploration of sexual and asexual domestication trajectories in other clonally propagated crops
Janus monolayers of transition metal dichalcogenides.
Structural symmetry-breaking plays a crucial role in determining the electronic band structures of two-dimensional materials. Tremendous efforts have been devoted to breaking the in-plane symmetry of graphene with electric fields on AB-stacked bilayers or stacked van der Waals heterostructures. In contrast, transition metal dichalcogenide monolayers are semiconductors with intrinsic in-plane asymmetry, leading to direct electronic bandgaps, distinctive optical properties and great potential in optoelectronics. Apart from their in-plane inversion asymmetry, an additional degree of freedom allowing spin manipulation can be induced by breaking the out-of-plane mirror symmetry with external electric fields or, as theoretically proposed, with an asymmetric out-of-plane structural configuration. Here, we report a synthetic strategy to grow Janus monolayers of transition metal dichalcogenides breaking the out-of-plane structural symmetry. In particular, based on a MoS2 monolayer, we fully replace the top-layer S with Se atoms. We confirm the Janus structure of MoSSe directly by means of scanning transmission electron microscopy and energy-dependent X-ray photoelectron spectroscopy, and prove the existence of vertical dipoles by second harmonic generation and piezoresponse force microscopy measurements
Lessons learned during down referral of antiretroviral treatment in Tete, Mozambique
As sub-Saharan African countries continue to scale up antiretroviral treatment, there has been an increasing emphasis on moving provision of services from hospital level to the primary health care clinic level. Delivery of antiretroviral treatment at the clinic level increases the number of entry points to care, while the greater proximity of services encourages retention in care
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