Increasingly, with the data collected at the LHC we are confronted with the possible existence of flow in pp collisions. In this work, we show that PYTHIA 8 produces flowlike effects in events with ...multiple hard subcollisions due to color string formations between final partons from independent hard scatterings, the so-called color reconnection. We present studies of different identified hadron observables in pp collisions at 7 TeV. Studies have been done both for minimum bias and multiplicity intervals in events with and without color reconnection to isolate the flowlike effect.
Data collected at the LHC are confronted with the possible existence of flow in pp collisions. Here we present a study inside the framework of PYTHIA 8, showing that it contains implicit flow-like ...effects coming from multiple hard subcollisions and color string formation between initial and final partons from independent hard scatterings: color reconnection. We present studies with strange hadron observables in pp collisions at 7 TeV. Studies have been done both for minimum bias and multiplicity intervals in events with and without color reconnection to isolate the flow-like effect.
During the 2017 record-breaking burning season in Canada/United States, intense wild fires raged during the first week of September in the Pacific northwestern region (British Columbia, Alberta, ...Washington, Oregon, Idaho, Montana and northern California) burning mostly temperate coniferous forests. The heavy loads of smoke particles emitted in the atmosphere reached the Iberian Peninsula (IP) a few days later on 7 and 8 September. Satellite imagery allows to identify two main smoke clouds emitted during two different periods that were injected and transported in the atmosphere at several altitude levels. Columnar properties on 7 and 8 September at two Aerosol Robotic Network (AERONET) mid-altitude, background sites in northern and southern Spain are: aerosol optical depth (AOD) at 440 nm up to 0.62, Ångström exponent of 1.6–1.7, large dominance of small particles (fine mode fraction >0.88), low absorption AOD at 440 nm (<0.008) and large single scattering albedo at 440 nm (>0.98). Profiles from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) show the presence of smoke particles in the stratosphere during the transport, whereas the smoke is only observed in the troposphere at its arrival over the IP. Portuguese and Spanish ground lidar stations from the European Aerosol Research Lidar Network/Aerosols, Clouds, and Trace gases Research InfraStructure Network (EARLINET/ACTRIS) and the Micro-Pulse Lidar NETwork (MPLNET) reveal smoke plumes with different properties: particle depolarization ratio and color ratio, respectively, of 0.05 and 2.5 in the mid troposphere (5–9 km) and of 0.10 and 3.0 in the upper troposphere (10–13 km). In the mid troposphere the particle depolarization ratio does not seem time-dependent during the transport whereas the color ratio seems to increase (larger particles sediment first). To analyze the horizontal and vertical transport of the smoke from its origin to the IP, particle dispersion modelling is performed with the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) parameterized with satellite-derived biomass burning emission estimates from the Global Fire Assimilation System (GFAS) of the Copernicus Atmosphere Monitoring Service (CAMS). Three compounds are simulated: carbon monoxide, black carbon and organic carbon. The results show that the first smoke plume which travels slowly reaches rapidly (~1 day) the upper troposphere and lower stratosphere (UTLS) but also shows evidence of large scale horizontal dispersion, while the second plume, entrained by strong subtropical jets, reaches the upper troposphere much slower (~2.5 days). Observations and dispersion modelling all together suggest that particle depolarization properties are enhanced during their vertical transport from the mid to the upper troposphere.
•Long-range transport of a smoke plume from northern America to Europe•Time-space monitoring with ground and space-borne lidars of a smoke plume•Injection of smoke particles up to the upper troposphere (<13 km)•Dispersion model parameterization with satellite-based biomass burning estimates•Possible rationales for the smoke absorption and depolarization properties observed
In this paper we extract the aerosol microphysical properties for a collection of mineral dust cases measured by multi-wavelength depolarization Raman lidar systems located at the National Technical ...University of Athens (NTUA, Athens, Greece) and the Andalusian Institute for Earth System Research (IISTA-CEAMA, Granada, Spain). The lidar-based retrievals were carried out with the Spheroidal Inversion eXperiments software tool (SphInX) developed at the University of Potsdam (Germany). The software uses regularized inversion of a two-dimensional enhancement of the Mie model based on the spheroid-particle approximation with the aspect ratio determining the particle shape. The selection of the cases was based on the transport time from the source regions to the measuring sites. The aerosol optical depth as measured by AERONET ranged from 0.27 to 0.54 (at 500 nm) depending on the intensity of each event. Our analysis showed the hourly mean particle linear depolarization ratio and particle lidar ratio values at 532 nm ranging from 11 to 34% and from 42 to 79 sr respectively, depending on the mixing status, the corresponding air mass pathways and their transport time. Cases with shorter transport time showed good agreement in terms of the optical and SphInX-retrieved microphysical properties between Athens and Granada providing a complex refractive index value equal to 1.4 + 0.004i. On the other hand, the results for cases with higher transport time deviated from the aforementioned ones as well as from each other, providing, in particular, an imaginary part of the refractive index ranging from 0.002 to 0.005. Reconstructions of two-dimensional shape-size distributions for each selected layer showed that the dominant effective particle shape was prolate with diverse spherical contributions. The retrieved volume concentrations reflect overall the intensity of the episodes.
•Inversion of a two-dimensional enhancement of the Mie model based on the spheroid-particle approximation.•Reconstructions of two-dimensional shape-size distributions for selected layers.•Focus on short range (pure) to long range (mixture) dust processes.•Mean δaer and LR values at 532 nm range from 11 to 34% and from 42 to 79 sr respectively, depending on the mixing state.•AOD as measured by AERONET ranged from 0.27 to 0.54 (at 500 nm) depending on the intensity of each event.
High impact low probability events (HILP) such as natural hazards significantly affect the infrastructure of power distribution systems (PDS) leading to considerable social and economic loss. This ...paper presents a novel methodology for optimizing resource and restoration scheduling in PDS after a natural hazards focusing on reducing operational costs during PDS recovery. The proposed methodology includes a mixed integer linear programming optimization problem in which a DC optimal power flow model is solved. The proposed methodology was evaluated in the IEEE 34-node test feeder and in a real-world case in two PDS: the San Rafael and Salcedo feeders in Cotopaxi-Ecuador. The results show the effectiveness of the proposed methodology compared with traditional recovery criteria.
Electric power systems (EPS) are facing challenges worldwide due to the increased occurrence of high-impact, low-probability (HILP) events, such as natural hazards. In this context, the concept of ...resilience has been considered in several studies. However, few studies have addressed the assessment of EPS resilience against volcanic eruptions with a focus on electrical structure damage. This paper proposes a methodology to assess the impact of ash deposits on the EPS. The methodology uses data sampling from historical ash deposit events to obtain probability density functions to then apply a Monte Carlo simulation (MCS) that can characterize the event and assess its impact on the electrical infrastructure through vulnerability curves. In addition, a DC optimal power flow model (DC-OPF) under contingencies was implemented to quantify different resilience metrics in terms of energy supply capacity, operation, and the infrastructure of the power system. The proposed methodology was applied to the Ecuadorian National Interconnected System (NIS) to assess the impact of an eruption of the Cotopaxi volcano. The results show our methodological framework evaluates resilience in terms of operation and infrastructure in EPS against the ash deposit, allowing mitigation plans to be better formulated.
The AEAOD– ΔAEAOD grid proposed by Gobbi et al. (2007) is a graphical method used to visually represent the spectral characterization of aerosol optical depth (AOD), i.e. Angström exponent (AE) and ...its curvature, in order to infer the fine mode contribution (η) to the total AOD and the size of the fine mode aerosol particles. Perrone et al. (2014) applied this method for the wavelengths widely used in lidar measurements. However, in neither case does the method allow for a direct relationship between η and the fine mode fraction contribution to the total aerosol population. Some discussions are made regarding the effect of shape and composition to the classical AE-ΔAE plot. The potential use of particle backscatter measurements, widely used in aerosol characterization methods together with extinction measurements, is also discussed in the AE-ΔAE grid context. A modification is proposed that yields the submicron contribution to the total volume concentration by using particle extinction data, and a comparison to experimental measurements is made. Our results indicate that the use of a modified AE-ΔAE grid plot to directly obtain submicrometric and micrometric mode fraction to the total aerosol population is feasible if a volume-based bimodal particle size distribution is used instead of a number-based one.
•AEAOD– ΔAEAOD graphical grid plots (Gobbi) yield fine-mode contribution to AOD.•A modified Gobbi plot is proposed that links fine-mode volume contribution to AOD.•The use of particle backscatter measurements is discussed in the AE-ΔAE grid context.
High probability and low impact events (HILP), such as natural disasters, represent a constant hazard for power distribution systems (PDS), the impact of these events on electri-cal infrastructure ...may cause considerable socio-economic losses. This paper presents a novel methodology for optimal PDS outage management due to natural disasters through the optimization of available resources of the distribution company and mobilization of repair crews to maximize the energy supplied and minimize the recovery time of the system. The methodology includes a mixed-integer linear programming (MILP), considering system operation constraints with a model of DC optimal power flow and constraints of resource emplacement and mobilization of repair crews. Crews are dispatched considering traveling time and repair time. The proposal was applied to the IEEE test feeder of 34 nodes, considering earthquakes, in which the vulnerability assessment of primary substations and reinforced concrete electrical poles are carried out. The results show that the energy not supplied for the system under study is reduced when our optimal model is considered compared to recovery using traditional expert criteria.
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