9,607 research outputs found
A Note on: `Algorithms for Connected Set Cover Problem and Fault-Tolerant Connected Set Cover Problem'
A flaw in the greedy approximation algorithm proposed by Zhang et al. for
minimum connected set cover problem is corrected, and a stronger result on the
approximation ratio of the modified greedy algorithm is established. The
results are now consistent with the existing results on connected dominating
set problem which is a special case of the minimum connected set cover problem.Comment: 6 pages, 1 figure, submitted to Theoretical Computer Scienc
Numerical Simulation of Compressible Reactive Flows
Numerical simulation has been widely employed to investigate the compressible flows since it is difficult to carry out the experimental measurements, especially in the reactive flows. The shock-wave capturing scheme will be necessary for resolving the compressible flows, and moreover the careful treatments of chemical reaction should be considered for proceeding numerical simulation stable and fast. Recently, the present authors have tried to establish a high-resolution numerical solver for computing the compressible reactive flows. This chapter presents the numerical procedures acquired in this solver for computing the fluxes using weighted essentially non-oscillatory (WENO) scheme, dealing with chemical stiffness problems, and tracing droplets and their interaction with the compressible fluids. As examples, the Taylor-Green vortex (TGV) problem considering the passive scalar mixing, the spatially developing reactive mixing layer flows taken gas-phase hydrogen, and liquid n-decane as fuel are simulated, respectively. Many important characteristics of flow, flame, and ignition are analyzed under the supersonic condition
T-SaS: Toward Shift-aware Dynamic Adaptation for Streaming Data
In many real-world scenarios, distribution shifts exist in the streaming data
across time steps. Many complex sequential data can be effectively divided into
distinct regimes that exhibit persistent dynamics. Discovering the shifted
behaviors and the evolving patterns underlying the streaming data are important
to understand the dynamic system. Existing methods typically train one robust
model to work for the evolving data of distinct distributions or sequentially
adapt the model utilizing explicitly given regime boundaries. However, there
are two challenges: (1) shifts in data streams could happen drastically and
abruptly without precursors. Boundaries of distribution shifts are usually
unavailable, and (2) training a shared model for all domains could fail to
capture varying patterns. This paper aims to solve the problem of sequential
data modeling in the presence of sudden distribution shifts that occur without
any precursors. Specifically, we design a Bayesian framework, dubbed as T-SaS,
with a discrete distribution-modeling variable to capture abrupt shifts of
data. Then, we design a model that enable adaptation with dynamic network
selection conditioned on that discrete variable. The proposed method learns
specific model parameters for each distribution by learning which neurons
should be activated in the full network. A dynamic masking strategy is adopted
here to support inter-distribution transfer through the overlapping of a set of
sparse networks. Extensive experiments show that our proposed method is
superior in both accurately detecting shift boundaries to get segments of
varying distributions and effectively adapting to downstream forecast or
classification tasks.Comment: CIKM 202
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