Optimal Management of Railway Perturbations by Means of an Integrated Support System for Real-Time Traffic Control

Automatic real-time control of railway traffic perturbations has recently received the attention of practitioners. The aim is to make use of mathematical algorithms to maintain the required service availability during unplanned disturbances to operations. In the literature many tools for real-time traffic control are proposed, but their effects on traffic have never been studied neither in real life nor in realistic simulation environments. We can mention only a few pilot tests and a unique installation in the Lötschberg Base tunnel in Switzerland, which is in any case an ad-hoc implementation not extendible to other case studies. In this paper we present the ON-TIME framework for the real-time management of railway traffic perturbations. The main innovation is a standard web service-oriented architecture that ensures scalability and flexibility. A standard RailML interface is used for the input/output data of the modules, allowing immediate applicability of the framework to any network having a RailML representation. The scalability makes the framework independent from the number of modules and the amount of data exchanged. The flexibility permits any module to be replaced with others having similar features. The framework is tested in a closed-loop with the simulation environment HERMES for a perturbed traffic scenario on the Swedish Iron Ore line. Tests are performed for two different replanning algorithms (ROMA and RECIFE) used as conflict detection and resolution modules of the framework. The analysis represents a proof-of-concept to confirm the effectiveness of our framework in automatically solving conflicts and deadlocks during perturbed traffic conditions.Transport & PlanningCivil Engineering and Geoscience

High-Throughput Characterization of Single-Quantum-Dot Emission Spectra and Spectral Diffusion by Multiparticle Spectroscopy

In recent years, quantum dots (QDs) have emerged as bright, color-tunable light sources for various applications such as light-emitting devices, lasing, and bioimaging. One important next step to advance their applicability is to reduce particle-to-particle variations of the emission properties as well as fluctuations of a single QD’s emission spectrum, also known as spectral diffusion (SD). Characterizing SD is typically inefficient as it requires time-consuming measurements at the single-particle level. Here, however, we demonstrate multiparticle spectroscopy (MPS) as a high-throughput method to acquire statistically relevant information about both fluctuations at the single-particle level and variations at the level of a synthesis batch. In MPS, we simultaneously measure emission spectra of many (20-100) QDs with a high time resolution. We obtain statistics on single-particle emission line broadening for a batch of traditional CdSe-based core-shell QDs and a batch of the less toxic InP-based core-shell QDs. The CdSe-based QDs show significantly narrower homogeneous line widths, less SD, and less inhomogeneous broadening than the InP-based QDs. The time scales of SD are longer in the InP-based QDs than in the CdSe-based QDs. Based on the distributions and correlations in single-particle properties, we discuss the possible origins of line-width broadening of the two types of QDs. Our experiments pave the way to large-scale, high-throughput characterization of single-QD emission properties and will ultimately contribute to facilitating rational design of future QD structures.ChemE/Opto-electronic Material

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Measurement of charged particle multiplicities and densities in pp collisions at s√=7 TeV in the forward region

Charged particle multiplicities are studied in proton–proton collisions in the forward region at a centre-ofmass energy of √ s = 7 TeV with data collected by the LHCb detector. The forward spectrometer allows access to a kinematic range of 2.0 < η < 4.8 in pseudorapidity, momenta greater than 2 GeV/c and transverse momenta greater than 0.2 GeV/c. The measurements are performed using events with at least one charged particle in the kinematic acceptance. The results are presented as functions of pseudorapidity and transverse momentum and are compared to predictions from several Monte Carlo event generators