Nonlinear dynamics and band transport in a superlattice driven by a plane wave

A quantum particle transport induced in a spatially-periodic potential by a propagating plane wave has a number important implications in a range of topical physical systems. Examples include acoustically driven semiconductor superlattices and cold atoms in optical crystal. Here we apply kinetic description of the directed transport in a superlattice beyond standard linear approximation, and utilize exact path-integral solutions of the semiclassical transport equation. We show that the particle drift and average velocities have non-monotonic dependence on the wave amplitude with several prominent extrema. Such nontrivial kinetic behaviour is related to global bifurcations developing with an increase of the wave amplitude. They cause dramatic transformations of the system phase space and lead to changes of the transport regime. We describe different types of phase trajectories contributing to the directed transport and analyse their spectral content

Direct CP, T and/or CPT violations in the K^0-\bar{K^0} system - Implications of the recent KTeV results on 2π2\pi decays -

The recent results on the CP violating parameters Re(e'/e) and \Delta\phi = \phi_{00}-\phi_{+-} reported by the KTeV Collaboration are analyzed with a view to constrain CP, T and CPT violations in a decay process. Combining with some relevant data compiled by the Particle Data Group, we find Re(e_2-e_0) = (0.85 +- 3.11)*10^{-4} and Im(e_2-e_0) = (3.2 +- 0.7)*10^{-4}, where Re(e_I) and Im(e_I) represent respectively CP/CPT and CP/T violations in decay of K^0 and \bar{K^0} into a 2\pi state with isospin I.Comment: 7 pages, No figure

Space and water heating in UK multi-residential buildings: comparison of heating systems and heating design parameters

Space and water heating comprise a large part of the energy needs of a domestic building. The energy performance of the heating systems depends directly on their operating efficiency and indirectly on the heat losses of the building. This study examines the energy performance of various space and water heating systems in a multi-residential building in the UK. Multi-residential buildings are characterised by diverse use of the spaces and the services by the occupants with consequent varying heating loads and operation schedules that the heating systems have to deal with. The energy performance of the systems is analysed in terms of energy consumption, C02 emissions and running cost. Heating design parameters such as localisation or centralisation of the installation of the systems, ventilation rate and heating set point temperature are also examined and their potential of saving heating energy is estimated. Results showed that a ground source heat pump system produces the lowest C02 emissions (5.92 tnC02 per annum) amongst the systems examined (9.76 tnC02 per annum in average). A localised gas-fired warm air system can save 8% of C02 emissions compared to a centralised version of the same system. Great savings can be achieved by lowering the ventilation rate (23%-26% C02 reduction) and lowering the heating set point temperature (23%-27% CQ2 reduction)

Bulk Power Grid Risk Analysis: Ranking Infrastructure Elements According to their Risk Significance

Disruptions in the bulk power grid can result in very diverse consequences that include economic, social, physical, and psychological impacts. In addition, power outages do not affect all end-users of the system in the same manner. For these reasons, a risk analysis of bulk power systems requires more than determining the likelihood and magnitude of power outages; it must also include the diverse impacts power outages have on the users of the system. We propose a methodology for performing a risk analysis on the bulk power system. A power flow simulation model is used to determine the likelihood and extent of power outages when components within the system fail to perform their designed function. The consequences associated with these failures are determined by looking at the type and number of customers affected. Stakeholder input is used to evaluate the relative importance of these consequences. The methodology culminates with a ranking of each system component by its risk significance to the stakeholders. The analysis is performed for failures of infrastructure elements due to both random causes and malevolent acts

Recent developments in GEANT 4

Fil: Depaola, Gerardo Osvaldo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.GEANT4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection. Over the past several years, major changes have been made to the toolkit in order to accommodate the needs of these user communities, and to efficiently exploit the growth of computing power made available by advances in technology. The adaptation of GEANT4 to multithreading, advances in physics, detector modeling and visualization, extensions to the toolkit, including biasing and reverse Monte Carlo, and tools for physics and release validation are discussed here.info:eu-repo/semantics/publishedVersionFil: Depaola, Gerardo Osvaldo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Física de Partículas y Campo

Findings of a review of spacecraft fire safety needs

Discussions from a workshop to guide UCLA and NASA investigators on the state of knowledge and perceived needs in spacecraft fire safety and its risk management are reviewed, for an introduction to an analytical and experimental project in this field. The report summarizes the workshop discussions and includes the visual aids used in the presentations. Probabilistic Safety Assessment (PSA) methods, which are currently not used, would be of great value to the designs and operation of future human-crew spacecraft. Key points in the discussions were the importance of understanding and testing smoldering as a likely fire scenario in space and the need for smoke damage modeling, since many fire-risk models ignore this mechanism and consider only heat damage

Risk-based Spacecraft Fire Safety Experiments

Viewgraphs on risk-based spacecraft fire safety experiments are presented. Spacecraft fire risk can never be reduced to a zero probability. Probabilistic risk assessment is a tool to reduce risk to an acceptable level

Water-related ecosystems' mapping and assessment based on remote sensing techniques and geospatial analysis: The SWOS national service case of the Greek Ramsar sites and their catchments

Water-related ecosystems' mapping and assessment based on remote sensing techniques and geospatial analysis: The SWOS national service case of the Greek Ramsar sites and their catchments. Remote Sensing of Environment 245 (2020) 111795. doi.org/10.1016/j.rse.2020.11179