The new cloud computing paradigm: the way to IT seen as a utility

In the present competitive environment, companies are wondering how to reduce their IT costs while increasing their efficiency and agility to react when changes in the business processes are required. Cloud Computing is the latest paradigm to optimize the use of IT resources considering ?everything as a service? and receiving these services from the Cloud (Internet) instead of owning and managing hardware and software assets. The benefits from the model are clear. However, there are also concerns and issues to be solved before Cloud Computing spreads across the different industries. This model will allow a pay-per-use model for the IT services and many benefits like cost savings, agility to react when business demands changes and simplicity because there will not be any infrastructure to operate and administrate. It will be comparable to the well known utilities like electricity, water or gas companies. However, this paper underlines several risk factors of the model. Leading technology companies should research on solutions to minimize the risks described in this article. Keywords - Cloud Computing, Utility Computing, Elastic Computing, Enterprise Agilit

Un intento de medición de la vulnerabilidad ante la exclusión social

Este trabajo se ha desarrollado dentro del proyecto de investigación “La última red de protección social en España” (SEC97-1377) del Plan Nacional de I+D.Las rentas mínimas de inserción (RMI) han supuesto un revulsivo frente a antiguas políticas de transferencias que pretendían meramente aumentar el nivel de ingresos regulares de los beneficiarios. Las RMI de los años noventa en Europa han generado un renovado interés por los aspectos no exclusivamente monetarios de la pobreza, que se ha unido con el concepto de exclusión social. Al mismo tiempo las RMI basan sus criterios de acceso en la renta del individuo y diseñando después medidas de inserción para sus beneficiarios. Esto significa que la única medición operativa con que contamos de la exclusión es la de ser beneficiario de un programa de rentas mínimas. No obstante, los criterios de políticas que han ido naciendo para hacer frente a una realidad que ha ido surgiendo (o haciéndose visible socialmente aunque existiera previamente) no tienen por qué responder a las reflexiones y tipologías establecidas por los especialistas. Así, para establecer un determinado cómputo de excluidos sería conveniente que éste estuviera conectado con un concepto claro de exclusión social. Para acometer el intento de proponer tales criterios de medición vamos a basarnos en las aproximaciones sociológica y económica al concepto de exclusión social. El concepto de exclusión social no es ciertamente nuevo dentro del ámbito de la sociología, aunque sí que lo es dentro del análisis económico. En este trabajo se apuesta por la utilidad de realizar una interpretación económica de determinados análisis sociológicos de la exclusión social, que, a nuestro juicio, puede permitir acometer mediciones con grandes encuestas para detectar colectivos vulnerables ante la exclusión social, ya que la detección de excluidos gracias a ese tipo de encuestas es sumamente difícil debido a las propias características de este colectivo. Para desarrollar este objetivo se revisa, en primer lugar, cómo puede realizarse ese encaje entre los análisis sociológicos de la exclusión con la economía, partiendo de las líneas de investigación tradicionales sobre la pobreza en Europa. En segundo lugar, se pasa a explicar cómo se puede intentar medir la exclusión social, teniendo en cuenta este enfoque económico. En tercer lugar, se aplica la propuesta a la primera ola del Panel de Hogares de la Unión Europea correspondiente a España (en adelante, PHOGUE). Finalmente, se ofrecen unas conclusiones que recogen las principales aportaciones de nuestra investigación

Optimization of actuation and cooling systems for advanced convergent-divergent nozzles of combat aircraft

The system or components of a convergent-divergent (CONDI) nozzle that offer better perspectives for improvement and optimization are the actuation and cooling systems. Performance offers little margin for a direct improvement, and the utilization of advanced materials in many components of the nozzle presents no specific problems as compared with those of other parts of the engine, with the exception of the petals, in which the introduction of ceramic materials has a direct influence on cooling and performance, and it will be included in the cooling optimization. The introduction of a thrust vectoring capability is a major improvement, though not the subjet of this paper. The problem of the optimization of the actuation system was preliminary discussed in ref. 1, mainly in connection with the utilization of one versus two parameters actuation system. Since that time, SENER and FTP have carried out many studies and tests on actuation systems and on cooling optimization. They have also accumulated experience by means of theoretical and experimental studies on the utilization of ceramic petals. Some results and the main conclusions of these studies and tests are presented in the present work

Calidad, evaluación y acreditación en la educación superior: a propósito de un proyecto de reforma en Colombia / Quality, assessment, and accreditation in higher education: reflections on a legislative initiative in Colombia

El artículo se centra en la propuesta de reforma de la educación superior del gobierno del presidente Juan Manuel Santos, que pretende orientarse a la calidad. Analiza el concepto de calidad en el campo educativo y en el texto de proyecto de reforma. Concluye que la reforma se inscribe en el desplazamiento que se ha venido dando en estos últimos años de un Estado de bienestar hacia un Estado “evaluador” en el sentido planteado por Guy Neave. / Abastract. This article evaluates the legislative initiative presented by the government of Juan Manuel Santos (2011) that aims to improve the quality of higher education in Colombia, by analyzing the concept of educational quality. Our analysis concludes that the reform is part of a shift that has been made in recent years from a “welfare state” to an “evaluative state” (Neave 1988)

Aplicación de una formulación numérica de elementos finitos para el estudio de problemas de transporte convectivo en zonas portuarias

IV Congreso de Métodos Numéricos en Ingeniería, 1999, Sevilla[Resumen] La ecuación diferencial del trasporte por convección-difusión permite modelizar un gran número de procesos de interés en la ingeniería. Así, fenómenos com el estudio de la distribución de temperaturas en una pieza mecánica, la evolución de la concentración de una sustancia en un medio poroso, o la dispersión de un contaminante en un medio fluido son descritos eficazmente por dicha ecuación. En este artículo se estudia un problema de dispersión de un contaminante debido a un vertido accidental en un área portuaria determinada. Primeramente se resuelve un problema de difusión pura, en el cual se supone que el fluido está en reposo en todo el dominio. Posteriormente, se resuelven problemas con convección, a partir de un campo de velocidades conocido. Se comprobará que si la velocidad es elevada aparecen oscilaciones espúreas en ciertas partes del dominio, y se apuntará el origen de dichas oscilaciones, así como los distintos esquemas propuestos para la estabilización de las formulaciones numéricas

Constrained simulations, nested simulation semantics and counting bisimulations

Nested simulations define an interesting hierarchy of semantic preorders and equivalences in which every semantics refines the previous one and it is refined by the following. This nested nature provides a fruitful framework for the study of the formal meaning and the properties of concurrent processes. In this paper we present the notion of constrained simulation that, although rather simple, allows us to find general results for a wide family of semantics. In particular, we provide an axiomatization for both the preorder and the equivalence induced by any constrained simulation. Nested simulations are constrained simulations and therefore our results can be instantiated directly to them. Besides, constrained simulations suggest the definition of a new family of semantics, generalised nested simulation semantics, constructed over the base of any order relation, instead of plain simulation. Finally, we conclude the study of the (generalised) nested semantics defining a generalisation of bisimulation relations, counting bisimulation, that allows us to define a characterisation of nested semantics in terms of a bisimulation-like game

Bisimulations Up-to for the Linear Time Branching Time Spectrum

Coinductive definitions of semantics based on bisimulations have rather pleasant properties and are simple to use. In order to get coinductive characterisations of those semantic equivalences that are weaker than strong bisimulation we use a variant of the bisimulation up-to technique in which we allow the use of a given preorder relation. We prove that under some technical conditions our bisimulations up-to characterise the kernel of the given preorder. It is remarkable that the adequate orientation of the ordering relation is crucial to get this result. As a corollary, we get nice coinductive characterisations of all the axiomatic semantic equivalences in Van Glabbeek’s spectrum. Although we first prove our results for finite processes, reasoning by induction, then we see, by using continuity arguments, that they are also valid for infinite (finitary) processes

Process equivalences as global bisimulations

Bisimulation can be defined in a simple way using coinductive methods, and has rather pleasant properties. Ready similarity was proposed by Meyer et al. as a way to weakening the bisimulation equivalence thus getting a semantics defined in a similar way, but supported for more reasonable (weaker) observational properties. Global bisimulations were introduced by Frutos et al. in order to study different variants of non-determinism getting, in particular, a semantics under which the internal choice operator becomes associative. Global bisimulations are defined as plain bisimulations but allowing the use of new moves, called global transitions, that can change the processes not only locally in its head, but anywhere. Now we are continuing the study of global bisimulation but focusing on the way different semantics can be characterised as global bisimulation semantics. In particular, we have studied ready similarity, on the one hand because it was proposed as the strongest reasonable semantics weaker than bisimulation; on the other hand, because ready similarity was not directly defined as an equivalence relation but as the nucleus of an order relation, and this open the question whether it is also possible to define it as a symmetric bisimulation-like semantics. We have got a simple and elegant characterisation of ready similarity as a global bisimulation semantics, that provides a direct symmetric characterisation of it as an equivalence relation, without using any order as intermediate concept. Besides, we have found that it is not necessary to start from a simulation based semantics to get an equivalent global bisimulation. What has proved to be very useful is the axiomatic characterization of the semantics. Following these ideas we have got also global bisimulation for several semantics, including refusals and traces. That provides a general framework that allows to relate both intensional and extensional semantics

Preserving contexts for soft conformance relation

This paper addresses the study of bisimulation based conformance relations in which input and output actions not presented in the specification are added to the implementation. A new definition, that we called soft conformance, is given. Then, we concentrate on the study of the conditions under which a context preserves the soft conformance relation of two agents. These conditions depend both on the specification and the implementation in the conformance relation and also on the context. Since the addition of extraneous actions to the implementation allows to define malicious contexts that would not preserve the conformance relation, such a characterisation of the family of contexts preserving each individual pair (implementation and specification) in the conformance relation is the best result that can be expected in this direction

(Bi)Simulations Up-to Characterise Process Semantics

We define (bi)simulations up-to a preorder and show how we can use them to provide a coinductive, (bi)simulation-like, characterisation of semantic (equivalences) preorders for processes. In particular, we can apply our results to all the semantics in the linear time-branching time spectrum that are defined by preorders coarser than the ready simulation preorder. The relation between bisimulations up-to and simulations up-to allows us to find some new relations between the equivalences that define the semantics and the corresponding preorders. In particular, we have shown that the simulation up-to an equivalence relation is a canonical preorder whose kernel is the given equivalence relation. Since all of these canonical preorders are defined in an homogeneous way, we can prove properties for them in a generic way. As an illustrative example of this technique, we generate an axiomatic characterisation of each of these canonical preorders, that is obtained simply by adding a single axiom to the axiomatization of the original equivalence relation. Thus we provide an alternative axiomatization for any axiomatizable preorder in the linear time-branching time spectrum, whose correctness and completeness can be proved once and for all. Although we first prove, by induction, our results for finite processes, then we see, by using continuity arguments, that they are also valid for infinite (finitary) processes