Page 83 - Fister jr., Iztok, Andrej Brodnik, Matjaž Krnc and Iztok Fister (eds.). StuCoSReC. Proceedings of the 2019 6th Student Computer Science Research Conference. Koper: University of Primorska Press, 2019
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Table 3 the average F1 score results is visible in the spec-
tral domain. Despite that different paths led us to the archi-
tecture of SkipFCN, the main drive was to achieve compa-
rable performance to time-domain models since input space
was heavily redundant. For keeping our evaluations sym-
metric and providing a reference for evaluating identical ar-
chitectures on the spectral domain, we list results of the
same networks shown in Table 2.

Computational requirements. The delay and complex-

ity of our proposed model, depicted in Figure 1 is mainly
characterized by the Fourier transform, and the complexity
of the two parallel branches, working on time and frequency
domain respectively. In total the model has fewer than 2
million trainable parameters, that takes up 8 MB storage
using 32-bit precision representation. We performed exten-
sive time complexity measurements on the proposed model,
using a single P100 Graphics Processor Unit. For the train-
ing, we used the mini-batch size of 64 with early-stopping
after 100 epochs on the training data. On average, each
training took 1 hour before reaching a peak of accuracy. In
real-time operation (inference) using Fourier Transform win-
dow size of 255, the model requires 354 measurement points
to evaluate the first response. Based on the sampling rate of
the recording device (300 Hz) that translates to a 1.18s ef-
fective delay. Furthermore, we measured how fast the model
evaluates a 20s window. Without computing samples in par-
allel, the time-domain branch takes 1.33 ms ± 821 ns and
the frequency-domain branch takes 1.54 ms ± 1.48 µs to ex-
tract features, in total the inference takes 1.68 ms ± 2.11
µs. Using a batch size of 100 we can parallelize the compu-
tations with a sub-linear increase in time cost: 18.6 ms ±
21.9 µs on time-domain, 32.1 ms ± 127 µs on the frequency
domain, 39.1 ms ± 482 µs when branches are computed in
parallel.

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