221 research outputs found
Change Point Modeling of Covid-19 Data in the United States
To simultaneously model the change point and the possibly nonlinear relationship in the Covid-19 data of the US, a continuous second-order free knot spline model was proposed. Using the least squares method, the change point of the daily new cases against the total confirmed cases up to the previous day was estimated to be 04 April 2020. Before the point, the daily new cases were proportional to the total cases with a ratio of 0.287, suggesting that each patient had 28.7% chance to infect another person every day. After the point, however, such ratio was no longer maintained and the daily new cases were decreasing slowly. At the individual state level, it was found that most states had change points. Before its change point for each state, the daily new cases were still proportional to the total cases. And all the ratios were about the same except for New York State in which the ratio was much higher (probably due to its high population density and heavy usage of public transportation). But after the points, different states had different patterns. One interesting observation was that the change point of one state was about 3 weeks lagged behind the state declaration of emergency. This might suggest that there was a lag period, which could help identify possible causes for the second wave. In the end, consistency and asymptotic normality of the estimates were briefly discussed where the criterion functions are continuous but not differentiable (irregular)
Coded Speech Quality Measurement by a Non-Intrusive PESQ-DNN
Wideband codecs such as AMR-WB or EVS are widely used in (mobile) speech
communication. Evaluation of coded speech quality is often performed
subjectively by an absolute category rating (ACR) listening test. However, the
ACR test is impractical for online monitoring of speech communication networks.
Perceptual evaluation of speech quality (PESQ) is one of the widely used
metrics instrumentally predicting the results of an ACR test. However, the PESQ
algorithm requires an original reference signal, which is usually unavailable
in network monitoring, thus limiting its applicability. NISQA is a new
non-intrusive neural-network-based speech quality measure, focusing on
super-wideband speech signals. In this work, however, we aim at predicting the
well-known PESQ metric using a non-intrusive PESQ-DNN model. We illustrate the
potential of this model by predicting the PESQ scores of wideband-coded speech
obtained from AMR-WB or EVS codecs operating at different bitrates in noisy,
tandeming, and error-prone transmission conditions. We compare our methods with
the state-of-the-art network topologies of QualityNet, WaweNet, and DNSMOS --
all applied to PESQ prediction -- by measuring the mean absolute error (MAE)
and the linear correlation coefficient (LCC). The proposed PESQ-DNN offers the
best total MAE and LCC of 0.11 and 0.92, respectively, in conditions without
frame loss, and still is best when including frame loss. Note that our model
could be similarly used to non-intrusively predict POLQA or other (intrusive)
metrics. Upon article acceptance, code will be provided at GitHub
FedBRB: An Effective Solution to the Small-to-Large Scenario in Device-Heterogeneity Federated Learning
Recently, the success of large models has demonstrated the importance of
scaling up model size. This has spurred interest in exploring collaborative
training of large-scale models from federated learning perspective. Due to
computational constraints, many institutions struggle to train a large-scale
model locally. Thus, training a larger global model using only smaller local
models has become an important scenario (i.e., the \textbf{small-to-large
scenario}). Although recent device-heterogeneity federated learning approaches
have started to explore this area, they face limitations in fully covering the
parameter space of the global model. In this paper, we propose a method called
\textbf{FedBRB} (\underline{B}lock-wise \underline{R}olling and weighted
\underline{B}roadcast) based on the block concept. FedBRB can uses small local
models to train all blocks of the large global model, and broadcasts the
trained parameters to the entire space for faster information interaction.
Experiments demonstrate FedBRB yields substantial performance gains, achieving
state-of-the-art results in this scenario. Moreover, FedBRB using only minimal
local models can even surpass baselines using larger local models
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