42 resultados para Radiation Protection.
Resumo:
This paper focuses on QoS routing with protection in an MPLS network over an optical layer. In this multi-layer scenario each layer deploys its own fault management methods. A partially protected optical layer is proposed and the rest of the network is protected at the MPLS layer. New protection schemes that avoid protection duplications are proposed. Moreover, this paper also introduces a new traffic classification based on the level of reliability. The failure impact is evaluated in terms of recovery time depending on the traffic class. The proposed schemes also include a novel variation of minimum interference routing and shared segment backup computation. A complete set of experiments proves that the proposed schemes are more efficient as compared to the previous ones, in terms of resources used to protect the network, failure impact and the request rejection ratio
Resumo:
The radiation distribution function used by Domínguez and Jou [Phys. Rev. E 51, 158 (1995)] has been recently modified by Domínguez-Cascante and Faraudo [Phys. Rev. E 54, 6933 (1996)]. However, in these studies neither distribution was written in terms of directly measurable quantities. Here a solution to this problem is presented, and we also propose an experiment that may make it possible to determine the distribution function of nonequilibrium radiation experimentally. The results derived do not depend on a specific distribution function for the matter content of the system
Resumo:
Proyecto de investigación elaborado a partir de una estancia en el Institute for Atmospheric and Climate Science, a Alemanya, entre 2010 y 2012. La radiación solar que alcanza la superficie terrestre es un factor clave entre los procesos que controlan el clima de la Tierra, dado el papel que desempeñan en el balance energético y el ciclo hidrológico. Establecer su contribución al cambio climático reciente supone una gran dificultad debido a la complejidad de los procesos implicados, la gran cantidad de información requerida, y la incertidumbre de las bases de datos disponibles en la actualidad. Así, el objetivo principal del proyecto ha consistido en generar una base de datos de insolación incluyendo las series más largas (desde finales del siglo XIX) disponibles en toda Europa. Esta base de datos complementa para nuestro continente el Global Energy Balance Archive (GEBA) que mantiene y gestiona el grupo que ha acogido al receptor de la ayuda postdoctoral, y permite extender espacial (especialmente en países del sur de Europa) y temporalmente las series climáticas disponibles de mediciones de irradiancia solar. Como la insolación es un proxy de la irradiancia solar, el proyecto actual también ha tratado de calibrar de forma exhaustiva ambas variables, a fin de generar una nueva base de datos reconstruida de esta segunda variable que esté disponible desde finales del siglo XIX en Europa. Un segundo objetivo del proyecto ha consistido en continuar trabajando a escala de mayor detalle sobre la Península Ibérica, con el fin de proporcionar una mejor comprensión del fenómeno del “global dimming/brightening” y su impacto en el ciclo hidrológico y balance energético. Finalmente, un tercer objetivo del presente proyecto postdoctoral ha consistido en continuar estudiando los posibles ciclos semanales a gran escala de diferentes variables climáticas, línea de investigación de interés para la detección de posibles efectos de los aerosoles antrópicos en el clima a escalas temporales breves, y consecuentemente estrechamente vinculado al fenómeno del “global dimming/brightening”.
Resumo:
We analyze the political support for employment protection legislation. Unlike my previous work on the same topic, this paper pays a lot of attention to the role of obsolescence in the growth process. In voting in favour of employment protection, incumbent employees trade off lower living standards (because employment protection maintains workers in less productive activities) against longer job duration. The support for employment protection will then depend on the value of the latter relative to the cost of the former. We highlight two key deeterminants of this trade-off: first, the workers' bargaining power, second, the economy's growth rate-more precisely its rate of creative destruction.
Resumo:
We develop a model to analyse the implications of firing costs on incentives for R&D and international specialization. The Key idea is paying the firing cost, the country with a rigid labor market will tend to produce relatively secure goods, at a late stage of their product life cycle. Under international trade, an international product cycle emerges where, roughly, new goods are first produced in the low firing cost country will specialize in 'secondary innovations', that is, improvements in existing goods, while the low firing cost country will more specialize in 'primary innovation', that is, invention of new goods.
Resumo:
We analyze the political support for employment protection legislation.Unlike my previous work on the same topic, this paper pays a lot ofattention to the role of obsolescence in the growth process.In voting in favour of employment protection, incumbent employeestrade off lower living standards (because employment protectionmaintains workers in less productive activities) against longer jobduration. The support for employment protection will then depend onthe value of the latter relative to the cost of the former. Wehighlight two key deeterminants of this trade-off: first, the workers'bargaining power, second, the economy's growth rate-more preciselyits rate of creative destruction.
Resumo:
Labor market regulations have often being blamed for high and persistentunemployment in Europe, but evidence on their impact remains mixed. Morerecently, attention has turned to the impact of product market regulationson employment growth. This paper analyzes how labor and product marketregulations interact to affect turnover and employment. We present a matchingmodel which illustrates how barriers to entry in the product market mitigatethe impact of labor market deregulation. We, then, use the Italian SocialSecurity employer-employee panel to study the interaction between barriersto entry and dismissal costs. We exploit the fact that costs for unjustdismissals in Italy increased for firms below 15 employees relative to biggerfirms after 1990. We find that the increase in dismissal costs after 1990decreased accessions and separations in small relative to big firms,especially for women. Moreover, consistent with our model, we find evidencethat the increase in dismissal costs had smaller effects on turnover for womenin sectors faced with strict product market regulations.
Resumo:
This paper develops a model of job creation and job destruction in agrowing economy with embodied technical progress, that we use toanalyze the political support for employment protection legislationssuch as the ones that are observed in most European countries.We analyze the possibility of Condorcet cycles due to the fact thatworkers about to become unemployed prefer both an increase and areduction in firing costs over the status quo. Despite this problem, we show the existence of local, and sometimes global majority winners.In voting in favour of employment protection, incumbent employeestrade off lower living standards (because employment protectionmaintains workers in less productive activities) against longer job duration. We show that the gains from, and consequently the politicalsupport for employment protection (as defined by maximunjob tenure) are larger, the lower the rate of creative destruction and the largerthe worker's bargaining power. Numerical simulations suggest a hump-shaped response of firing costs to these variables, as well as negative impact of exogeneous turnover on employment protection.
Resumo:
We develop a model to analyse the implications of firing costs on incentivesfor R&D and international specialization. The Key idea is paying the firingcost, the country with a rigid labor market will tend to produce relativelysecure goods, at a late stage of their product life cycle.Under international trade, an international product cycle emerges where,roughly, new goods are first produced in the low firing cost country willspecialize in 'secondary innovations', that is, improvements in existinggoods, while the low firing cost country will more specialize in 'primaryinnovation', that is, invention of new goods.
Resumo:
The interest in solar ultraviolet (UV) radiation from the scientific community and the general population has risen significantly in recent years because of the link between increased UV levels at the Earth's surface and depletion of ozone in the stratosphere. As a consequence of recent research, UV radiation climatologies have been developed, and effects of some atmospheric constituents (such as ozone or aerosols) have been studied broadly. Correspondingly, there are well-established relationships between, for example, total ozone column and UV radiation levels at the Earth's surface. Effects of clouds, however, are not so well described, given the intrinsic difficulties in properly describing cloud characteristics. Nevertheless, the effect of clouds cannot be neglected, and the variability that clouds induce on UV radiation is particularly significant when short timescales are involved. In this review we show, summarize, and compare several works that deal with the effect of clouds on UV radiation. Specifically, works reviewed here approach the issue from the empirical point of view: Some relationship between measured UV radiation in cloudy conditions and cloud-related information is given in each work. Basically, there are two groups of methods: techniques that are based on observations of cloudiness (either from human observers or by using devices such as sky cameras) and techniques that use measurements of broadband solar radiation as a surrogate for cloud observations. Some techniques combine both types of information. Comparison of results from different works is addressed through using the cloud modification factor (CMF) defined as the ratio between measured UV radiation in a cloudy sky and calculated radiation for a cloudless sky. Typical CMF values for overcast skies range from 0.3 to 0.7, depending both on cloud type and characteristics. Despite this large dispersion of values corresponding to the same cloud cover, it is clear that the cloud effect on UV radiation is 15–45% lower than the cloud effect on total solar radiation. The cloud effect is usually a reducing effect, but a significant number of works report an enhancement effect (that is increased UV radiation levels at the surface) due to the presence of clouds. The review concludes with some recommendations for future studies aimed to further analyze the cloud effects on UV radiation
Resumo:
Microquasars are potential candidates to produce a non-negligible fraction of the observed galactic cosmic rays. The protons accelerated at the jet termination shock interact with the interstellar medium and may produce detectable fluxes of extended emission at different energy bands: high-energy and very high-energy gamma-rays produced by neutral pion-decay, synchrotron and bremsstrahlung emission in a wide energy range generated by the secondary electrons produced by charged pion-decay. We discuss the association between this scenario and some of the unidentified EGRET sources in the galactic plane.
Resumo:
The right of a person to be protected from natural hazards is a characteristic of the social and economical development of the society. This paper is a contribution to the reflection about the role of Civil Protection organizations in a modern society. The paper is based in the inaugural conference made by the authors on the 9th Plinius Conference on Mediterranean Storms. Two major issues are considered. The first one is sociological; the Civil Protection organizations and the responsible administration of the land use planning should be perceived as reliable as possible, in order to get consensus on the restrictions they pose, temporary or definitely, on the individual free use of the territory as well as in the entire warning system. The second one is technological: in order to be reliable they have to issue timely alert and warning to the population at large, but such alarms should be as "true" as possible. With this aim, the paper summarizes the historical evolution of the risk assessment, starting from the original concept of "hazard", introducing the concepts of "scenario of event" and "scenario of risk" and ending with a discussion about the uncertainties and limits of the most advanced and efficient tools to predict, to forecast and to observe the ground effects affecting people and their properties. The discussion is centred in the case of heavy rains and flood events in the North-West of Mediterranean Region.
Resumo:
The most important features of the proposed spherical gravitational wave detectors are closely linked with their symmetry. Hollow spheres share this property with solid ones, considered in the literature so far, and constitute an interesting alternative for the realization of an omnidirectional gravitational wave detector. In this paper we address the problem of how a hollow elastic sphere interacts with an incoming gravitational wave and find an analytical solution for its normal mode spectrum and response, as well as for its energy absorption cross sections. It appears that this shape can be designed having relatively low resonance frequencies (~ 200 Hz) yet keeping a large cross section, so its frequency range overlaps with the projected large interferometers. We also apply the obtained results to discuss the performance of a hollow sphere as a detector for a variety of gravitational wave signals.
Resumo:
Outgoing radiation is introduced in the framework of the classical predictive electrodynamics using LorentzDiracs equation as a subsidiary condition. In a perturbative scheme in the charges the first radiative self-terms of the accelerations, momentum and angular momentum of a two charge system without external field are calculated.
Resumo:
We deal with a classical predictive mechanical system of two spinless charges where radiation is considered and there are no external fields. The terms (2,2)Paa of the expansion in the charges of the HamiltonJacobi momenta are calculated. Using these, together with known previous results, we can obtain the paa up to the fourth order. Then we have calculated the radiated energy and the 3-momentum in a scattering process as functions of the impact parameter and the incident energy for the former and 3-momentum for the latter. Scattering cross-sections are also calculated. Good agreement with well known results, including those of quantum electrodynamics, has been found.