402 research outputs found
Polyphonic audio tagging with sequentially labelled data using CRNN with learnable gated linear units
Audio tagging aims to detect the types of sound events occurring in an audio
recording. To tag the polyphonic audio recordings, we propose to use
Connectionist Temporal Classification (CTC) loss function on the top of
Convolutional Recurrent Neural Network (CRNN) with learnable Gated Linear Units
(GLU-CTC), based on a new type of audio label data: Sequentially Labelled Data
(SLD). In GLU-CTC, CTC objective function maps the frame-level probability of
labels to clip-level probability of labels. To compare the mapping ability of
GLU-CTC for sound events, we train a CRNN with GLU based on Global Max Pooling
(GLU-GMP) and a CRNN with GLU based on Global Average Pooling (GLU-GAP). And we
also compare the proposed GLU-CTC system with the baseline system, which is a
CRNN trained using CTC loss function without GLU. The experiments show that the
GLU-CTC achieves an Area Under Curve (AUC) score of 0.882 in audio tagging,
outperforming the GLU-GMP of 0.803, GLU-GAP of 0.766 and baseline system of
0.837. That means based on the same CRNN model with GLU, the performance of CTC
mapping is better than the GMP and GAP mapping. Given both based on the CTC
mapping, the CRNN with GLU outperforms the CRNN without GLU.Comment: DCASE2018 Workshop. arXiv admin note: text overlap with
arXiv:1808.0193
Sound Event Detection with Sequentially Labelled Data Based on Connectionist Temporal Classification and Unsupervised Clustering
Sound event detection (SED) methods typically rely on either strongly
labelled data or weakly labelled data. As an alternative, sequentially labelled
data (SLD) was proposed. In SLD, the events and the order of events in audio
clips are known, without knowing the occurrence time of events. This paper
proposes a connectionist temporal classification (CTC) based SED system that
uses SLD instead of strongly labelled data, with a novel unsupervised
clustering stage. Experiments on 41 classes of sound events show that the
proposed two-stage method trained on SLD achieves performance comparable to the
previous state-of-the-art SED system trained on strongly labelled data, and is
far better than another state-of-the-art SED system trained on weakly labelled
data, which indicates the effectiveness of the proposed two-stage method
trained on SLD without any onset/offset time of sound events
Adapting the wine industry in China to climate change: Challenges and opportunities
Recently, China has become an exciting wine consumer market and one of the most important wine producers. China?s domestic wine industry is in the enviable position of contributing approximately 70 % of the total wine consumed with a 1.36 billion population market and the second largest world economy. Current studies of the Chinese wine industry are mostly focused on the wine market. However, global climate change, which affects the quantity, quality and distribution of wine, will have a strong impact on the Chinese domestic wine industry. In this paper, we characterize the impact of climate change in China and establish policy, financial, technical, institutional and collaborative adaptation strategies for the Chinese wine industry
A low phase noise microwave frequency synthesizer based on parameters optimized NLTL for Cs fountain clock
We report on the development and phase noise performance of a 9.1926 GHz
microwave frequency synthesizer to be used as the local oscillator for a Cs
fountain clock. It is based on frequency multiplication and synthesis from an
ultralow phase noise 5 MHz Oven Controlled Crystal Oscillator (OCXO) and 100
MHz Voltage Controlled Crystal Oscillator (VCXO).The key component of the
frequency multiplication is a non-linear transmission-line (NLTL) used as a
frequency comb generator. The phase noise of the synthesizer is improved by
carefully optimizing the input power, the input and output impedances of the
NLTL. The absolute phase noises of the 9.1926 GHz output signal are measured to
be -64 dBc/Hz, -83 dBc/Hz, -92 dBc/Hz, -117 dBc/Hz and -119 dBc/Hz at 1 Hz,
10Hz, 100Hz, 1 kHz and 10 kHz offset frequencies, respectively. The residual
phase noise of the synthesizer is measured to be -82 dBc/Hz at 1 Hz offset
frequency. The measurement result shows that the absolute phase noise at the
frequency range of 1 - 100 Hz is mainly limited by the phase noise of the OCXO.
The contribution of the absolute phase noise to the fountain clock short-term
frequency stability is calculated to be 7.0x10^(-14). The residual frequency
stability of the synthesizer is measured to be1.5x10^(-14), which is consistent
with the calculated frequency stability due to the residual phase noise of the
synthesizer. Meanwhile we designed and realized an interferometric microwave
switch in the synthesizer to eliminate the frequency shifts induced by the
microwave leakage. The extinction ratio of the switch is measured to be more
than 50 dB. In the scheme, we use only commercially available components to
build the microwave frequency synthesizer with excellent phase noise
performance for high-performance Cs fountain clocks
Nowhere to Hide: Cross-modal Identity Leakage between Biometrics and Devices
Along with the benefits of Internet of Things (IoT) come potential privacy risks, since billions of the connected devices are granted permission to track information about their users and communicate it to other parties over the Internet. Of particular interest to the adversary is the user identity which constantly plays an important role in launching attacks. While the exposure of a certain type of physical biometrics or device identity is extensively studied, the compound effect of leakage from both sides remains unknown in multi-modal sensing environments. In this work, we explore the feasibility of the compound identity leakage across cyber-physical spaces and unveil that co-located smart device IDs (e.g., smartphone MAC addresses) and physical biometrics (e.g., facial/vocal samples) are side channels to each other. It is demonstrated that our method is robust to various observation noise in the wild and an attacker can comprehensively profile victims in multi-dimension with nearly zero analysis effort. Two real-world experiments on different biometrics and device IDs show that the presented approach can compromise more than 70\% of device IDs and harvests multiple biometric clusters with ~94% purity at the same time
Full-range Gate-controlled Terahertz Phase Modulations with Graphene Metasurfaces
Local phase control of electromagnetic wave, the basis of a diverse set of
applications such as hologram imaging, polarization and wave-front
manipulation, is of fundamental importance in photonic research. However, the
bulky, passive phase modulators currently available remain a hurdle for
photonic integration. Here we demonstrate full-range active phase modulations
in the Tera-Hertz (THz) regime, realized by gate-tuned ultra-thin reflective
metasurfaces based on graphene. A one-port resonator model, backed by our
full-wave simulations, reveals the underlying mechanism of our extreme phase
modulations, and points to general strategies for the design of tunable
photonic devices. As a particular example, we demonstrate a gate-tunable THz
polarization modulator based on our graphene metasurface. Our findings pave the
road towards exciting photonic applications based on active phase
manipulations
- …