120,150 research outputs found
Real-time traffic forecasting with recent DTA methods
No full textIn this paper we revisit the real-time traffic forecasting problem. We review recently proposed Dynamic Traffic Assignment (DTA) methods and verify how they can improve the practice of traffic forecasting. In particular, we analyze: 1) the Gradient projection DTA model of Gentile (2016), 2) Day-to-day model by Watling and Cantarella (2016), 3) the Marginal Computation (MaC) method by Corthout et al. (2014), 4) dynamic origin-destination (O-D) demand estimation methods (Kostic and Gentile, 2015) and 5) the event rerouting model (Kucharski and Gentile, 2014). We discuss how these methods can be applied to improve short-term forecasting and, most importantly, if they are efficient and mature enough for practical, real-time implementations. We formulate the real-time DTA forecasting problem which searches for the solution using all of the above DTA methods. The main contribution of this paper can be seen as a review and synthesis of recently proposed DTA methods, summarized with conceptual real-time forecasting framework
Using traffic data of various types in the estimation of dynamic O-D matrices
No full textDynamic Traffic Assignment (DTA) has become a
main component of modern traffic control centres. To calibrate a
DTA model the observations from the field are required. There
has been increasing number of sensors and technologies which
can provide these data. In this paper we briefly describe these
sensors and elaborate on the various traffic data types that are
used in dynamic demand calibration. The methodology for
dynamic demand calibration using various data types is
presented. We test several of these data types and provide the
comparison of their effectiveness. As this is an optimization
problem we test three derivative-free optimization algorithms
and provide their comparison. The advantages and
disadvantages of different traffic data as well as of optimization
algorithms are discussed
Dorsal root ganglion – a potential new therapeutic target for neuropathic pain
No full textDamir Sapunar, Sandra Kostic, Adriana Banozic, Livia PuljakDepartment of Anatomy, Histology, and Embryology, University of Split Medical School, Soltanska 2, 21000 Split, CroatiaAbstract: A regional approach can protect our patients from often unacceptable adverse effects produced by systematically applied drugs. Regional therapeutic approaches, as well as interventions at the level of the peripheral nervous system and particularly the dorsal root ganglion (DRG), represent an alternative to the systemic application of therapeutic agents. This article provides an overview of DRG anatomical peculiarities, explains why the DRG is an important therapeutic target, and how animal models of targeted drug delivery can help us in the translation of basic research into clinical practice.Keywords: dorsal root ganglion, neuropathic pain, pain therapy, targeted drug deliver
Design of Proportional-Resonant Control for Current Harmonic Compliance in Electric Railway Power Systems
No full textThis paper presents the process of designing proportional-resonant controller for a four-quadrant rectifier in electric railway traction system. In the context of ever-stricter power quality and electromagnetic compatibility standards in electric railway power systems, developers of electric locomotives need to adapt with new ways to comply. This paper develops on the process of designing a four-quadrant rectifier proportional-resonant control for mitigation of low frequency current harmonic distortion, a novel method in the field of railway EMC. The control parameters are determined through analytical modeling of the rectifier through transfer functions. For the purpose of studying the harmonic distortion mitigation effects, only the current control loop was modeled and designed. The modeling starts with simplification of the model via large-signal modeling of the power converter. The parameters of the circuit then were used to develop the transfer functions, and select the appropriate parameter values of the current loop plant. The control loop and parameters were evaluated on test locomotive to validate the control, with results confirming the improved impact on the electromagnetic compatibility and conformity to regulation
Exploring a new breadth of cyclic steps on distal submarine fans
No full textResearch on the depositional record of submarine fans and related turbidite
systems has highlighted the importance of channel, lobe and lev ́ee–overbank
architectural elements as fundamental building blocks. However, many of
the characteristics and processes of deposits left by flows traversing those
fans remain elusive, because flows seem to be able to go unconfined for long
distances. Offshore southern California (USA), the La Jolla Canyon decreases
in relief to become an approximately U-shaped channel across the basin
floor of the San Diego Trough. The La Jolla Channel gradually loses confinement
and transitions to a network of scours, some of which align to form
incipient channels, and fields of bedforms. High-resolution seafloor topography,
CHIRP seismic-reflection data, sediment cores and hydrodynamic flow
analysis are used to explore these features. The focus is on two regions of
bedforms: (i) a field of net-depositional, concentric bedforms across the eastern
lev ́ee–overbank upstream from the terminus of the La Jolla Channel; and
(ii) a linear train of more erosional bedforms approximating an incipient
channel adjacent to the present mouth of the La Jolla Channel. These bedforms
are interpreted to be among a class of upper-flow-regime bedforms
called cyclic steps, which were formed by densimetric Froude supercritical
turbidity currents that spilled out of the present La Jolla Channel. The highresolution
data for the La Jolla Fan provide valuable insights into the characteristics
of supercritical bedforms likely common to distal submarine fans, as
well as on sedimentary processes likely important for submarine fan growth
into sedimentary basins. In particular, the pattern of evolution of the La Jolla
Fan suggests that cyclic steps with wavelengths on the order of tens of
metres to a few hundreds of metres could be fundamentally important for
the evolution of the distal submarine fans with relatively low-relief main
channels
Influence of the build orientation on the fatigue strength of EOS maraging steel produced by additive metal machine
No full textThis paper presents a research dealing with the dependence of the fatigue strength of maraging steel parts, manufactured by direct selective laser sintering, on the production build orientation. Three sets of specimens have been manufactured according to the ISO 1143 Standard (2010) by EOSINT M280 additive manufacturing machine, with the following heat and mechanical treatments, in agreement with the recommendations by the material manufacturer and current literature. The expected outcomes are the Fatigue Limit values of the material and the maximum number of cycles observed at different stress levels for three different build orientations (three different angles, 0°, 45° and 90°, between the build direction and the longitudinal axis of the samples). The results have been processed and compared by statistical methods in order to determine the fatigue curves in the finite life domain and the fatigue limits, along with their confidence bands and intervals, and to investigate the significance of the build orientation factor
Numerical analysis of a 3-D printed porous trailing edge for broadband noise reduction
No full textLattice Boltzmann simulations were carried out to investigate the noise mitigation mechanisms of a 3-D printed porous trailing-edge insert, elucidating the link between noise reduction and material permeability. The porous insert is based on a unit cell resembling a lattice of diamond atoms. It replaces the last 20 % chord of a NACA 0018 at zero angle-of-attack. A partially blocked insert is considered by adding a solid partition between 84 % and 96 % of the aerofoil chord. The regular porous insert achieves a substantial noise reduction at low frequencies, although a slight noise increase is found at high frequencies. The partially blocked porous insert exhibits a lower noise reduction level, but the noise emission at mid-to-high frequency is slightly affected. The segment of the porous insert near the tip plays a dominant role in promoting noise mitigation, whereas the solid-porous junction contributes, in addition to the rough surface, towards the high-frequency excess noise. The current study demonstrates the existence of an entrance length associated with the porous material geometry, which is linked to the pressure release process that is responsible for promoting noise mitigation. This process is characterised by the aerodynamic interaction between pressure fluctuations across the porous medium, which is found at locations where the porous insert thickness is less than twice the entrance length. Present results also suggest that the noise attenuation level is related to both the chordwise extent of the porous insert and the streamwise turbulent length scale. The porous inserts also cause a slight drag increase compared to their solid counterpart. Wind Energ
An aggregate approach for the calibration of time-dependent demand in Dynamic Traffic Assignment models using SPSA algorithm
No full textDemand calibration in Dynamic Traffic Assignment is often regarded as an optimization problem. The most widely algorithm used in the literature is SPSA, using single O-D pairs as calibration variables. This approach is very difficult to apply to large-scale networks due to the large number of variables. In this paper we present a novel approach that can lead to superior demand calibration results. It consists of the aggregation of single demand components based on a correlation object. An analytical model was created to represent real-world dynamics and is used for tests. We tested different scenarios regarding different levels of measurement errors. The results show that the calibration using SPSA algorithm with total origin demand and total destination demand can converge to the solution, whereas using standard approach, i.e. O-D pair calibration, breaks. This approach has a number of advantages which are analysed and discussed
On the applicability of the Fujisaki–Okamoto transformation to the BIKE KEM
No full textThe QC-MDPC code-based KEM BIKE is one of the Round-3 candidates of the NIST PQC standardization project. Its Round-2 specification document described variants claiming to have IND-CCA security. The security proof used the Fujisaki–Okamoto transformation and a decoder targeting a Decoding Failure Rate (DFR) of (Formula presented.) (for Level-1 security). However, several aspects needed to be amended in order for the IND-CCA proof to hold. The main issue is that using a decoder with DFR of (Formula presented.) does not necessarily imply that the underlying PKE is δ-correct with (Formula presented.), as required. In this paper, we handle the necessary aspects to ensure the security claim is correct. In particular, we close the gap in the proof by defining the notion of message-agnostic PKE. We show that the PKEs underlying the BIKE versions are message-agnostic. This implies that BIKE with a decoder that has a sufficiently low DFR is also an IND-CCA KEM
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