37,159 research outputs found
Initial synchronisation of wideband and UWB direct sequence systems: single- and multiple-antenna aided solutions
This survey guides the reader through the open literature on the principle of initial synchronisation in single-antenna-assisted single- and multi-carrier Code Division Multiple Access (CDMA) as well as Direct Sequence-Ultra WideBand (DS-UWB) systems, with special emphasis on the DownLink (DL). There is a paucity of up-to-date surveys and review articles on initial synchronization solutions for MIMO-aided and cooperative systems - even though there is a plethora of papers on both MIMOs and on cooperative systems, which assume perfect synchronization. Hence this paper aims to ?ll the related gap in the literature
Top-quark mass measurements: review and perspectives
The top quark is the heaviest elementary particle known and its mass () is a fundamental parameter of the Standard Model (SM). The
value affects theory predictions of particle production cross-sections required
for exploring Higgs-boson properties and searching for New Physics (NP). Its
precise determination is essential for testing the overall consistency of the
SM, to constrain NP models, through precision electroweak fits, and has an
extraordinary impact on the Higgs sector, and on the SM extrapolation to
high-energies. The methodologies, the results, and the main theoretical and
experimental challenges related to the measurements and
combinations at the Large Hadron Collider (LHC) and at the Tevatron are
reviewed and discussed. Finally, the prospects for the improvement of the
precision during the upcoming LHC runs are briefly outlined.Comment: 18 pages, 2 figures, Preprint submitted to Reviews in Physics (REVIP
A study of the proton spectra following the capture of in Li and C with FINUDA
Momenta spectra of protons emitted following the capture of in Li
and C have been measured with 1% resolution. The C spectrum is
smooth whereas for Li a well defined peak appears at about 500 MeV/. The
first observation of a structure in this region was identified as a strange
tribaryon or, possibly, a -nuclear state. The peak is correlated with a
coming from decay in flight, selected by setting momenta
larger than 275 MeV/. The could be produced, together with a 500
MeV/ proton, by the capture of a in a deuteron-cluster substructure of
the Li nucleus. The capture rate for such a reaction is (1.62\pm
0.23_{stat} ^{+0.71}_{-0.44}(sys))%/K^-_{stop}, in agreement with the existing
observations on He targets and with the hypothesis that the Li nucleus
can be interpreted as a cluster.Comment: 21 pages, 10 figures. Accepted for publication in NP
An autonomous GNSS anti-spoofing technique
open3siIn recent years, the problem of Position, Navigation and Timing (PNT) resiliency has received significant attention due to an increasing awareness on threats and the vulnerability of the current GNSS signals. Several proposed solutions make uses of cryptography to protect against spoofing. A limitation of cryptographic techniques is that they introduce a communication and processing computation overhead and may impact the performance in terms of availability and continuity for GNSS users. This paper introduces autonomous non cryptographic antispoofing mechanisms, that exploit semi-codeless receiver techniques to detect spoofing for signals with a component making use of spreading code encryption.openCaparra, Gianluca; Wullems, Christian; Ioannides, Rigas T.Caparra, Gianluca; Wullems, Christian; Ioannides, Rigas T
Tellipsoid: Exploiting inter-gene correlation for improved detection of differential gene expression
Motivation: Algorithms for differential analysis of microarray data are vital
to modern biomedical research. Their accuracy strongly depends on effective
treatment of inter-gene correlation. Correlation is ordinarily accounted for in
terms of its effect on significance cut-offs. In this paper it is shown that
correlation can, in fact, be exploited {to share information across tests},
which, in turn, can increase statistical power.
Results: Vastly and demonstrably improved differential analysis approaches
are the result of combining identifiability (the fact that in most microarray
data sets, a large proportion of genes can be identified a priori as
non-differential) with optimization criteria that incorporate correlation. As a
special case, we develop a method which builds upon the widely used two-sample
t-statistic based approach and uses the Mahalanobis distance as an optimality
criterion. Results on the prostate cancer data of Singh et al. (2002) suggest
that the proposed method outperforms all published approaches in terms of
statistical power.
Availability: The proposed algorithm is implemented in MATLAB and in R. The
software, called Tellipsoid, and relevant data sets are available at
http://www.egr.msu.edu/~desaikeyComment: 19 pages, Submitted to Bioinformatic
Accelerating Permutation Testing in Voxel-wise Analysis through Subspace Tracking: A new plugin for SnPM
Permutation testing is a non-parametric method for obtaining the max null
distribution used to compute corrected -values that provide strong control
of false positives. In neuroimaging, however, the computational burden of
running such an algorithm can be significant. We find that by viewing the
permutation testing procedure as the construction of a very large permutation
testing matrix, , one can exploit structural properties derived from the
data and the test statistics to reduce the runtime under certain conditions. In
particular, we see that is low-rank plus a low-variance residual. This
makes a good candidate for low-rank matrix completion, where only a very
small number of entries of ( of all entries in our experiments)
have to be computed to obtain a good estimate. Based on this observation, we
present RapidPT, an algorithm that efficiently recovers the max null
distribution commonly obtained through regular permutation testing in
voxel-wise analysis. We present an extensive validation on a synthetic dataset
and four varying sized datasets against two baselines: Statistical
NonParametric Mapping (SnPM13) and a standard permutation testing
implementation (referred as NaivePT). We find that RapidPT achieves its best
runtime performance on medium sized datasets (), with
speedups of 1.5x - 38x (vs. SnPM13) and 20x-1000x (vs. NaivePT). For larger
datasets () RapidPT outperforms NaivePT (6x - 200x) on all
datasets, and provides large speedups over SnPM13 when more than 10000
permutations (2x - 15x) are needed. The implementation is a standalone toolbox
and also integrated within SnPM13, able to leverage multi-core architectures
when available.Comment: 36 pages, 16 figure
Hadron Correlations Measured with ALICE
Angular particle correlations are a powerful tool to study collective effects
and in-medium jet modification as well as their interplay in the hot and dense
medium produced in central heavy-ion collisions. We present measurements of
two-particle angular correlations of inclusive charged and identified particles
performed with the ALICE detector. The near-side peak in the short-range
correlation region is quantitatively analyzed: while the rms of the peak in
-direction is independent of centrality within uncertainties, we find a
significant broadening in -direction from peripheral to central
collisions. The particle content of the near-side peak is studied finding that
the ratio of particles associated to a trigger particle is much smaller
than the one in the bulk of the particles and consistent with fragmentation of
a parton in vacuum.Comment: Proceedings of plenary talk at the 5th international conference on
hard and electromagnetic probes of high-energy nuclear collisions (Hard
Probes 2012), Cagliari, Ital
Long-Term Visual Object Tracking Benchmark
We propose a new long video dataset (called Track Long and Prosper - TLP) and
benchmark for single object tracking. The dataset consists of 50 HD videos from
real world scenarios, encompassing a duration of over 400 minutes (676K
frames), making it more than 20 folds larger in average duration per sequence
and more than 8 folds larger in terms of total covered duration, as compared to
existing generic datasets for visual tracking. The proposed dataset paves a way
to suitably assess long term tracking performance and train better deep
learning architectures (avoiding/reducing augmentation, which may not reflect
real world behaviour). We benchmark the dataset on 17 state of the art trackers
and rank them according to tracking accuracy and run time speeds. We further
present thorough qualitative and quantitative evaluation highlighting the
importance of long term aspect of tracking. Our most interesting observations
are (a) existing short sequence benchmarks fail to bring out the inherent
differences in tracking algorithms which widen up while tracking on long
sequences and (b) the accuracy of trackers abruptly drops on challenging long
sequences, suggesting the potential need of research efforts in the direction
of long-term tracking.Comment: ACCV 2018 (Oral
Open heavy-flavour measurements in pp and p--Pb collisions with ALICE at the LHC
The ALICE detector is well suited to measure heavy-flavour (charm and beauty)
production via hadronic and semi-leptonic decay channels of heavy-flavour
particles. Here an overview of heavy-flavour measurements made with the ALICE
detector during Run 1 in pp and p--Pb collisions is presented and discussed.Comment: Proceedings of 55th International Winter Meeting on Nuclear Physics,
Bormio, Italy, 23-27 January 2017. 10 pages, 6 figure
Exploiting correlogram structure for robust speech recognition with multiple speech sources
This paper addresses the problem of separating and recognising speech in a monaural acoustic mixture with the presence of competing speech sources. The proposed system treats sound source separation and speech recognition as
tightly coupled processes. In the first stage sound source separation is performed in the correlogram domain. For periodic sounds, the correlogram exhibits symmetric tree-like structures whose stems are located on the delay
that corresponds to multiple pitch periods. These pitch-related structures are exploited in the study to group spectral components at each time frame. Local
pitch estimates are then computed for each spectral group and are used to form simultaneous pitch tracks for temporal integration. These processes segregate a spectral representation of the acoustic mixture into several time-frequency regions such that the energy in each region is likely to have originated from a single periodic sound source. The identified time-frequency regions, together
with the spectral representation, are employed by a `speech fragment decoder' which employs `missing data' techniques with clean speech models to simultaneously search for the acoustic evidence that best matches model sequences. The paper presents evaluations based on artificially mixed simultaneous speech utterances. A coherence-measuring experiment is first reported which quantifies the consistency of the identified fragments with a single source. The system is then evaluated in a speech recognition task and compared to a conventional fragment generation approach. Results show that the proposed system produces more coherent fragments over different conditions,
which results in significantly better recognition accuracy
- âŠ