155 research outputs found
Turbulent Flow Overtopping a Dam - A CFD Modeling Study
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
A Worst-Case Approximate Analysis of Peak Age-of-Information Via Robust Queueing Approach
A new timeliness metric, called Age-of-Information (AoI), has recently
attracted a lot of research interests for real-time applications with
information updates. It has been extensively studied for various queueing
models based on the probabilistic approaches, where the analyses heavily depend
on the properties of specific distributions (e.g., the memoryless property of
the exponential distribution or the i.i.d. assumption). In this work, we take
an alternative new approach, the robust queueing approach, to analyze the Peak
Age-of-Information (PAoI). Specifically, we first model the uncertainty in the
stochastic arrival and service processes using uncertainty sets. This enables
us to approximate the expected PAoI performance for very general arrival and
service processes, including those exhibiting heavy-tailed behaviors or
correlations, where traditional probabilistic approaches cannot be applied. We
then derive a new bound on the PAoI in the single-source single-server setting.
Furthermore, we generalize our analysis to two-source single-server systems
with symmetric arrivals, which involves new challenges (e.g., the service times
of the updates from two sources are coupled in one single uncertainty set).
Finally, through numerical experiments, we show that our new bounds provide a
good approximation for the expected PAoI. Compared to some well-known bounds in
the literature (e.g., one based on Kingman's bound under the i.i.d. assumption)
that tends to be inaccurate under light load, our new approximation is accurate
under both light and high loads, both of which are critical scenarios for the
AoI performance.Comment: Published in IEEE INFOCOM 202
Primary synovial sarcoma of the heart
Primary synovial sarcoma of the heart is very rare, accounting for 5% of cardiac malignancies.
Of the few cases reported in the literature to date, nearly all have had a very poor outcome.
We present a further case. This uncommon malignancy has no specific symptoms during its
development, which results in delayed diagnosis. Echocardiography, chest computed tomography,
and magnetic resonance imaging can provide effective information about this tumor.
With the identification of the characteristic and diagnostic chromosomal abnormality t(X; 18),
this malignancy will become increasingly recognized. Synovial sarcoma of the heart requires
surgical intervention to improve the prognosis. Adjuvant and/or genetic therapy pre- or postoperation
can help prolong life. Chemotherapy is usually recommended as it may benefit the
patients. The key to treatment in the future is to find new therapeutic agents. Further elucidation
of the effects of this chromosomal abnormality may lead to better-directed therapies in
future. (Cardiol J 2011; 18, 2: 128-133
Waiting but not Aging: Optimizing Information Freshness Under the Pull Model
The Age-of-Information is an important metric for investigating the
timeliness performance in information-update systems. In this paper, we study
the AoI minimization problem under a new Pull model with replication schemes,
where a user proactively sends a replicated request to multiple servers to
"pull" the information of interest. Interestingly, we find that under this new
Pull model, replication schemes capture a novel tradeoff between different
values of the AoI across the servers (due to the random updating processes) and
different response times across the servers, which can be exploited to minimize
the expected AoI at the user's side. Specifically, assuming Poisson updating
process for the servers and exponentially distributed response time, we derive
a closed-form formula for computing the expected AoI and obtain the optimal
number of responses to wait for to minimize the expected AoI. Then, we extend
our analysis to the setting where the user aims to maximize the AoI-based
utility, which represents the user's satisfaction level with respect to
freshness of the received information. Furthermore, we consider a more
realistic scenario where the user has no prior knowledge of the system. In this
case, we reformulate the utility maximization problem as a stochastic
Multi-Armed Bandit problem with side observations and leverage a special linear
structure of side observations to design learning algorithms with improved
performance guarantees. Finally, we conduct extensive simulations to elucidate
our theoretical results and compare the performance of different algorithms.
Our findings reveal that under the Pull model, waiting does not necessarily
lead to aging; waiting for more than one response can often significantly
reduce the AoI and improve the AoI-based utility in most scenarios.Comment: 15 pages. arXiv admin note: substantial text overlap with
arXiv:1704.0484
Extraction Optimization of Water-Extracted Mycelial Polysaccharide from Endophytic Fungus Fusarium oxysporum Dzf17 by Response Surface Methodology
Water-extracted mycelial polysaccharide (WPS) from the endophytic fungus Fusarium oxysporum Dzf17 isolated from Dioscorea zingiberensis was found to be an efficient elicitor to enhance diosgenin accumulation in D. zingigerensis cultures, and also demonstrated antioxidant activity. In this study, response surface methodology (RSM) was employed to optimize the extraction process of WPS from F. oxysporum Dzf17 using Box-Behnken design (BBD). The ranges of the factors investigated were 1β3 h for extraction time (X1), 80β100 Β°C for extraction temperature (X2), and 20β40 (v/w) for ratio of water volume (mL) to raw material weight (g) (X3). The experimental data obtained were fitted to a second-order polynomial equation using multiple regression analysis. Statistical analysis showed that the polynomial regression model was in good agreement with the experimental results with the determination coefficient (R2) of 0.9978. By solving the regression equation and analyzing the response surface contour plots, the extraction parameters were optimized as 1.7 h for extraction time, 95 Β°C for extraction temperature, 39 (v/w) for ratio of water volume (mL) to raw material weight (g), and with 2 extractions. The maximum value (10.862%) of WPS yield was obtained when the WPS extraction process was conducted under the optimal conditions
Effect of the deviation of the current density profile center on the three-dimensional non-transferred arc plasma torch
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