535 research outputs found
Revisiting the security of speaker verification systems against imposture using synthetic speech
In this paper, we investigate imposture using synthetic speech.
Although this problem was first examined over a decade ago,
dramatic improvements in both speaker verification (SV) and
speech synthesis have renewed interest in this problem. We
use a HMM-based speech synthesizer which creates synthetic
speech for a targeted speaker through adaptation of a background
model. We use two SV systems: standard GMMUBM-
based and a newer SVM-based. Our results show when
the systems are tested with human speech, there are zero false
acceptances and zero false rejections. However, when the systems
are tested with synthesized speech, all claims for the targeted
speaker are accepted while all other claims are rejected.
We propose a two-step process for detection of synthesized
speech in order to prevent this imposture. Overall, while SV
systems have impressive accuracy, even with the proposed detector,
high-quality synthetic speech will lead to an unacceptably
high false acceptance rate
Electronic and optical properties of LiBC
LiBC, a semiconducting ternary borocarbide constituted of the lightest
elements only, has been synthesized and characterized by x-ray powder
diffraction, dielectric spectroscopy, and conductivity measurements. Utilizing
an infrared microscope the phonon spectrum has been investigated in single
crystals. The in-plane B-C stretching mode has been detected at 150 meV,
noticeably higher than in AlB2, a non-superconducting isostructural analog of
MgB2. It is this stretching mode, which reveals a strong electron-phonon
coupling in MgB2, driving it into a superconducting state below 40 K, and is
believed to mediate predicted high-temperature superconductivity in hole-doped
LiBC [H. Rosner, A. Kitaigorodsky, and W. E. Pickett, Phys. Rev. Lett. 88,
127001 (2002)].Comment: 4 pages, 4 figure
Definitive chemoradiotherapy versus neoadjuvant chemoradiotherapy followed by radical surgery for locally advanced oesophageal squamous cell carcinoma:meta-analysis
Background: The literature lacks robust evidence comparing definitive chemoradiotherapy (dCRT) with neoadjuvant chemoradiotherapy and surgery (nCRS) for oesophageal squamous cell carcinoma (ESCC). This study aimed to compare long-term survival of these approaches in patients with ESCC.Methods: A systematic review performed according to PRISMA guidelines included studies identified from PubMed, Scopus, and Cochrane CENTRAL databases up to July 2021 comparing outcomes between dCRT and nCRS for ESCC. The main outcome measure was overall survival (OS), secondary outcome was disease-free survival (DFS). A meta-analysis was conducted using random-effects modelling to determine pooled adjusted multivariable hazard ratios (HRs).Results: Ten studies including 14 092 patients were included, of which 30 per cent received nCRS. Three studies were randomized clinical trials (RCTs) and the remainder were retrospective cohort studies. dCRT and nCRS regimens were reported in six studies and surgical quality control was reported in two studies. Outcomes for OS and DFS were reported in eight and three studies respectively. Following meta-analysis, nCRS demonstrated significantly longer OS (HR 0.68, 95 per cent c.i. 0.54 to 0.87, P < 0.001) and DFS (HR 0.50, 95 per cent c.i. 0.36 to 0.70, P < 0.001) compared with dCRT.Conclusion: Neoadjuvant chemoradiotherapy followed by oesophagectomy correlated with improved survival compared with definitive chemoradiation in the treatment of ESCC; however, there is a lack of literature on RCTs
The Evolution of Transport Across World Regions
This chapter aims at providing an overview of the multiple aspects involved in passenger and freight transport, which are the base for the understanding of the energy consumption of the sector, as well as for the current trends and prospects related to digitalization and decarbonization. A brief historical discussion and some trends will be presented, followed by a description of the main modes and technologies, both for passenger and freight transport, and a final focus on the differences across world regions in mobility patterns and behaviors. The evolution of transport systems has led to very different situations worldwide, depending on different strategies related to economic development, geographical limitations and cultural, political and social aspects. Proper sustainable mobility plans need to be based on the specific characteristics of each location, and the integration between different governance levels is of utmost importance to improve the reliability, affordability, and energy performance on the entire transport system
GT2006-91080 FLAME-OUT DETECTION FOR GAS TURBINE ENGINES BASED UPON THERMOCOUPLE SIGNAL ANALYSIS
ABSTRACT This paper describes an experimental study to examine the potential of using Exhaust Gas Temperature (EGT) thermocouples for prompt flame-out detection in gas turbine engines. The approach taken involved accelerating the response of a shielded, slow response thermocouple using electronic processing of the signal. Thus, the abrupt drop in temperature characteristic of a flame-out could be detected within a much shorter time period than would be possible through a conventional thermocouple temperature measurement method. This was intended to provide a robust alternative to existing optical flame-out sensors which have fast response but can be susceptible to false flame-out indications due to window sooting. A production EGT thermocouple with online electronic processing was compared with a production optical flame sensor from a GE F-404 and a laboratory photodiode sensing system. The devices were tested in a full scale GE J-85 combustion chamber sector rig with optical access. The results showed that the thermocouple flame sensor had a response time to flame-outs of less than 100 ms. This was much faster than a conventional thermocouple, but still an order of magnitude longer than the optical flame sensor. However, whereas the optical flame sensor could yield ambiguous results about the presence of flame under some conditions, the thermocouple flame sensor provided a clear indication of flame-out events for all the conditions that were tested
Velopark : a linked open data platform for bicycle parkings
Cycling as a mean of urban transportation is positively correlated with cleaner, healthier and happier cities. By providing more infrastructure, such as secure parking facilities, cities aim on attracting more cyclists. However, authoritative information about parking facilities is heavily decentralized and heterogeneous, which makes secure parking facilities harder to be discovered by cyclists. Can an open dataset about bike parkings be managed decentrally? In this paper, we present the results of the Velopark project, carried out in Belgium by different actors that include local public authorities, public transport operators and pro-cycling organizations. During the project execution we (i) introduced the Open Velopark Vocabulary as a common semantic data model; and (ii) implemented the Velopark platform, an open data publishing environment for both static and live authoritative parking data. So far, 1599 parking facilities were published through the Velopark platform, 31 different Belgian municipalities and 4 parking related organizations use the platform to describe, publish and manage their parking facilities. A common data publishing environment supports organizations for providing access to their information, while guaranteeing data reliability for cyclists. In future work we will further extend our data model to cover other kinds of infrastructure and bicycle-related services
Neighbourhood, Route and Workplace-Related Environmental Characteristics Predict Adults' Mode of Travel to Work
Commuting provides opportunities for regular physical activity which can reduce the risk of chronic disease. Commuters' mode of travel may be shaped by their environment, but understanding of which specific environmental characteristics are most important and might form targets for intervention is limited. This study investigated associations between mode choice and a range of objectively assessed environmental characteristics.Participants in the Commuting and Health in Cambridge study reported where they lived and worked, their usual mode of travel to work and a variety of socio-demographic characteristics. Using geographic information system (GIS) software, 30 exposure variables were produced capturing characteristics of areas around participants' homes and workplaces and their shortest modelled routes to work. Associations between usual mode of travel to work and personal and environmental characteristics were investigated using multinomial logistic regression.Of the 1124 respondents, 50% reported cycling or walking as their usual mode of travel to work. In adjusted analyses, home-work distance was strongly associated with mode choice, particularly for walking. Lower odds of walking or cycling rather than driving were associated with a less frequent bus service (highest versus lowest tertile: walking OR 0.61 [95% CI 0.20ā1.85]; cycling OR 0.43 [95% CI 0.23ā0.83]), low street connectivity (OR 0.22, [0.07ā0.67]; OR 0.48 [0.26ā0.90]) and free car parking at work (OR 0.24 [0.10ā0.59]; OR 0.55 [0.32ā0.95]). Participants were less likely to cycle if they had access to fewer destinations (leisure facilities, shops and schools) close to work (OR 0.36 [0.21ā0.62]) and a railway station further from home (OR 0.53 [0.30ā0.93]). Covariates strongly predicted travel mode (pseudo r-squared 0.74).Potentially modifiable environmental characteristics, including workplace car parking, street connectivity and access to public transport, are associated with travel mode choice, and could be addressed as part of transport policy and infrastructural interventions to promote active commuting
Phonon anomalies and electron-phonon interaction in RuSr_2GdCu_2O_8 ferromagnetic superconductor: Evidence from infrared conductivity
Critical behavior of the infrared reflectivity of RuSr_2GdCu_2O_8 ceramics is
observed near the superconducting T_{SC} = 45 K and magnetic T_M = 133 K
transition temperatures. The optical conductivity reveals the typical features
of the c-axis optical conductivity of strongly underdoped multilayer
superconducting cuprates. The transformation of the Cu-O bending mode at 288
cm^{-1} to a broad absorption peak at the temperatures between T^* = 90 K and
T_{SC} is clearly observed, and is accompanied by the suppression of spectral
weight at low frequencies. The correlated shifts to lower frequencies of the
Ru-related phonon mode at 190 cm^{-1} and the mid-IR band at 4800 cm^{-1} on
decreasing temperature below T_M are observed. It provides experimental
evidence in favor of strong electron-phonon coupling of the charge carriers in
the Ru-O layers which critically depends on the Ru core spin alignment. The
underdoped character of the superconductor is explained by strong hole
depletion of the CuO_2 planes caused by the charge carrier self-trapping at the
Ru moments.Comment: 11 pages incl. 5 figures, submitted to PR
Dynamic Bayesian belief network to model the development of walking and cycling schemes
This paper aims to describe a model which represents the formulation of decision-making processes (over a number of years) affecting the step-changes of walking and cycling (WaC) schemes. These processes can be seen as being driven by a number of causal factors, many of which are associated with the attitudes of a variety of factors, in terms of both determining whether any scheme will be implemented and, if it is implemented, the extent to which it is used. The outputs of the model are pathways as to how the future might unfold (in terms of a number of future time steps) with respect to specific pedestrian and cyclist schemes. The transitions of the decision making processes are formulated using a qualitative simulation method, which describes the step-changes of the WaC scheme development. In this article a Bayesian belief network (BBN) theory is extended to model the influence between and within factors in the dynamic decision making process
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