Distributed First Order Logic

Distributed First Order Logic (DFOL) has been introduced more than ten years ago with the purpose of formalising distributed knowledge-based systems, where knowledge about heterogeneous domains is scattered into a set of interconnected modules. DFOL formalises the knowledge contained in each module by means of first-order theories, and the interconnections between modules by means of special inference rules called bridge rules. Despite their restricted form in the original DFOL formulation, bridge rules have influenced several works in the areas of heterogeneous knowledge integration, modular knowledge representation, and schema/ontology matching. This, in turn, has fostered extensions and modifications of the original DFOL that have never been systematically described and published. This paper tackles the lack of a comprehensive description of DFOL by providing a systematic account of a completely revised and extended version of the logic, together with a sound and complete axiomatisation of a general form of bridge rules based on Natural Deduction. The resulting DFOL framework is then proposed as a clear formal tool for the representation of and reasoning about distributed knowledge and bridge rules

NA57 main results

The CERN NA57 experiment was designed to study the production of strange and multi-strange particles in heavy ion collisions at SPS energies; its physics programme is essentially completed. A review of the main results is presented.Comment: SQM 2007 Conference Proceeding

A study of the strengthening mechanisms in the novel precipitation hardening KEYLOS® 2001 Steel

KeyLos ® 2001 is a new precipitation-hardening steel especially developed for plastic moulds. In this study the precipitation stage of KeyLos ® 2001 steel has been investigated and compared to the results obtained with 17-4 PH steel. Precipitation-hardening has been carried out at three different temperatures and the stages of hardening and overageing have been studied in order to clarify the hardening mechanisms. It has been found that hardening and softening mechanism during the precipitation-hardening treatment occur at higher temperatures and in correspondence with more prolonged treatment times than those typical for the best known 17-4 PH steel; hardness is then expected to remain stable also for very extended mould lives. Microstructural investigations by means of Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) have also been carried out and the microstructural parameters responsible for the hardening and overageing have been pointed out

On the crack path of rolling contact fatigue cracks in a railway wheel steel

The objective of the present paper is to give some preliminary results obtained in the frame of a more wide investigation on the rolling contact fatigue (RCF) behavior of a railway wheel steel. The effect of different test parameters on the RCF fatigue strength of the railway wheel steel was evaluated. RCF tests were conducted using two cylindrical contact specimens under different Po/k ratio (where Po is the maximum Hertzian pressure, k is the yield stress in shear of the material), under dry contact conditions or with water lubrication, and at varying slip ratio. In the present study crack initiation location and crack growth direction were carefully investigated; microscopic examination showed that the cracks were initiated at the surface, propagated obliquely in the depth direction and then occasionally branched into two directions. Usually multiple cracks are initiated, at the rolling contact surface, caused by the accumulation of shear deformation due to repeated rolling–sliding contact loading. Subsequent crack growth has been found to occur along specific sloped directions. The influence of Po/k ratio, dry or wet contact, and slip ratio on crack slope angle to the radial direction and the depths at which slope changes occur has been investigated. Observed crack slopes and slope change position have been discussed according to crack path prediction criteria in the literature

Incremental Predictive Process Monitoring: How to Deal with the Variability of Real Environments

A characteristic of existing predictive process monitoring techniques is to first construct a predictive model based on past process executions, and then use it to predict the future of new ongoing cases, without the possibility of updating it with new cases when they complete their execution. This can make predictive process monitoring too rigid to deal with the variability of processes working in real environments that continuously evolve and/or exhibit new variant behaviors over time. As a solution to this problem, we propose the use of algorithms that allow the incremental construction of the predictive model. These incremental learning algorithms update the model whenever new cases become available so that the predictive model evolves over time to fit the current circumstances. The algorithms have been implemented using different case encoding strategies and evaluated on a number of real and synthetic datasets. The results provide a first evidence of the potential of incremental learning strategies for predicting process monitoring in real environments, and of the impact of different case encoding strategies in this setting

Measurement of pseudorapidity density of charged particles in proton-proton collisions with the ALICE Pixel detector

This note describes a procedure for measuring the pseudorapidity density distribution of charged particles, based on the tracklets reconstructed with the silicon pixel layers. Results on proton-proton Monte Carlo samples are presented

Buenas condiciones para el peatón. Recogida de información técnica

Se trata de un estudio sobre el peatón y sobre la percepción que tienen los estudiosos del tema, buscando las buenas condiciones para caminar a pie en las ciudades, siendo además esta manera la mas sostenible de desplazarse. Mientras se tenga una contextualización apoyada en diferentes autores y textos no se va a profundizar mucho en la literatura ni en experiencias anteriores; será más bien una opinión del autor, basada en su experiencia laboral y sus impresiones personales respecto a las condiciones que puedan ser consideradas favorables o satisfactorias para el desarrollo de desplazamientos a pié en los espacios urbanos, afectado por las circunstancias y considerando los requerimientos y las demandas actuales. El objetivo, si bien no es tan novedoso, se trata de buscar desde un punto de vista práctico a aquellos proyectos que van a diseñar nuevas zonas urbanas (urbanizaciones, plazas, calles etc.), pero sin la pretensión de ser una guía o manual para dicho labor