60 research outputs found
Towards a Deep Understanding of Multilingual End-to-End Speech Translation
In this paper, we employ Singular Value Canonical Correlation Analysis
(SVCCA) to analyze representations learnt in a multilingual end-to-end speech
translation model trained over 22 languages. SVCCA enables us to estimate
representational similarity across languages and layers, enhancing our
understanding of the functionality of multilingual speech translation and its
potential connection to multilingual neural machine translation. The
multilingual speech translation model is trained on the CoVoST 2 dataset in all
possible directions, and we utilize LASER to extract parallel bitext data for
SVCCA analysis. We derive three major findings from our analysis: (I)
Linguistic similarity loses its efficacy in multilingual speech translation
when the training data for a specific language is limited. (II) Enhanced
encoder representations and well-aligned audio-text data significantly improve
translation quality, surpassing the bilingual counterparts when the training
data is not compromised. (III) The encoder representations of multilingual
speech translation demonstrate superior performance in predicting phonetic
features in linguistic typology prediction. With these findings, we propose
that releasing the constraint of limited data for low-resource languages and
subsequently combining them with linguistically related high-resource languages
could offer a more effective approach for multilingual end-to-end speech
translation.Comment: Accepted to Findings of EMNLP 202
An Observed Correlation Between Thermal and Non-Thermal Emission in Gamma-Ray Bursts
Recent observations by the Gamma-ray Space Telescope have confirmed
the existence of thermal and non-thermal components in the prompt photon
spectra of some Gamma-ray bursts (GRBs). Through an analysis of six bright
Fermi GRBs, we have discovered a correlation between the observed photospheric
and non-thermal -ray emission components of several GRBs using a
physical model that has previously been shown to be a good fit to the Fermi
data. From the spectral parameters of these fits we find that the
characteristic energies, and , of these two components are
correlated via the relation which varies from
GRB to GRB. We present an interpretation in which the value of index
indicates whether the jet is dominated by kinetic or magnetic energy. To date,
this jet composition parameter has been assumed in the modeling of GRB outflows
rather than derived from the data
The GECAM Real-Time Burst Alert System
Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor
(GECAM), consisting of two micro-satellites, is designed to detect gamma-ray
bursts associated with gravitational-wave events. Here, we introduce the
real-time burst alert system of GECAM, with the adoption of the BeiDou-3 short
message communication service. We present the post-trigger operations, the
detailed ground-based analysis, and the performance of the system. In the first
year of the in-flight operation, GECAM was triggered by 42 GRBs. GECAM
real-time burst alert system has the ability to distribute the alert within
1 minute after being triggered, which enables timely follow-up
observations.Comment: 17 pages, 10 figures; Accepted for publication in RA
In-Orbit Instrument Performance Study and Calibration for POLAR Polarization Measurements
POLAR is a compact space-borne detector designed to perform reliable
measurements of the polarization for transient sources like Gamma-Ray Bursts in
the energy range 50-500keV. The instrument works based on the Compton
Scattering principle with the plastic scintillators as the main detection
material along with the multi-anode photomultiplier tube. POLAR has been
launched successfully onboard the Chinese space laboratory TG-2 on 15th
September, 2016. In order to reliably reconstruct the polarization information
a highly detailed understanding of the instrument is required for both data
analysis and Monte Carlo studies. For this purpose a full study of the in-orbit
performance was performed in order to obtain the instrument calibration
parameters such as noise, pedestal, gain nonlinearity of the electronics,
threshold, crosstalk and gain, as well as the effect of temperature on the
above parameters. Furthermore the relationship between gain and high voltage of
the multi-anode photomultiplier tube has been studied and the errors on all
measurement values are presented. Finally the typical systematic error on
polarization measurements of Gamma-Ray Bursts due to the measurement error of
the calibration parameters are estimated using Monte Carlo simulations.Comment: 43 pages, 30 figures, 1 table; Preprint accepted by NIM
Searching for gravitationally lensed Gamma-ray bursts with their afterglows
Gamma-ray bursts (GRBs) at high redshifts are expected to be gravitationally lensed by objects of different mass
scales. Other than a single recent claim, no lensed GRB has been detected so far by using gamma-ray data only. In
this paper, we suggest that multiband afterglow data might be an efficient way to search for lensed GRB events.
Using the standard afterglow model, we calculate the characteristics of the lensed afterglow lightcurves under the
assumption of two popular analytic lens models: the point-mass and singular isothermal sphere models. In
particular, when different lensed images cannot be resolved, their signals would be superimposed together with a
given time delay. In this case, the X-ray afterglows are likely to contain several X-ray flares of similar width in
linear scale and similar spectrum, and the optical afterglow lightcurve will show re-brightening signatures. Since
the lightcurves from the image arriving later would be compressed and deformed in the logarithmic timescale, the
larger time delay (i.e., the larger mass of the lens), the easier it is to identify the lensing effect. We analyzed the
archival data of optical afterglows and found one potential candidate of the lensed GRB (130831A) with time delay
∼500 s; however, observations of this event in gamma-ray and X-ray bands seem not to support the lensing
hypothesis. In the future, with the cooperation of the all-sky monitoring gamma-ray detectors and multiband sky
survey projects, the method proposed in this paper would be more efficient in searching for strongly lensed GRBs
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