HEOS 1 helium observations in the solar wind

Results of alpha-particle observations performed by the European satellite HEOS 1, in the period from December 9, 1968, to April 13, 1969, and from September 6, 1969, to April 15, 1970, are presented. The average bulk velocities of protons V sub p and alpha-particles V sub alpha appear to be equal; however, due to an instrumental bias, the possibility of V sub alpha being lower than V sub p cannot be ruled out. Comparison with observations of Vela 3 and Explorer 34 satellites gives evidence of a dependence of helium abundance on the solar cycle. The problem of the stability of differences between the bulk velocities of protons and alpha-particles is investigated. The behavior of alpha-particles through interplanetary shock waves is illustrated in connection with magnetic field measurements

Qualitative Uncertainty Orderings Revised

AbstractIn recent decades, qualitative approaches to probabilistic uncertainty have been receiving wider and wider attention. We propose a new characterization of some of the most adopted partial preference orders by providing an uniform axiomatic treatment of a variety of qualitative uncertainty notions. We prove a representation result that connects qualitative notions of partial uncertainty to their numerical counterparts. We also describe an executable specification, in the declarative framework of Answer Set Programming, that constitutes the core engine for the qualitative management of uncertainty. Some basic reasoning tasks are also identified

A graphical approach to relational reasoning

Relational reasoning is concerned with relations over an unspecified domain of discourse. Two limitations to which it is customarily subject are: only dyadic relations are taken into account; all formulas are equations, having the same expressive power as first-order sentences in three variables. The relational formalism inherits from the Peirce-Schröder tradition, through contributions of Tarski and many others. Algebraic manipulation of relational expressions (equations in particular) is much less natural than developing inferences in first-order logic; it may in fact appear to be overly machine-oriented for direct hand-based exploitation. The situation radically changes when one resorts to a convenient representation of relations based on labeled graphs. The paper provides details of this representation, which abstracts w.r.t. inessential features of expressions. Formal techniques illustrating three uses of the graph representation of relations are discussed: one technique deals with translating first-order specifications into the calculus of relations; another one, with inferring equalities within this calculus with the aid of convenient diagram-rewriting rules; a third one with checking, in the specialized framework of set theory, the definability of particular set operations. Examples of use of these techniques are produced; moreover, a promising approach to mechanization of graphical relational reasoning is outlined

Low yield metals and perforated steel shear walls for seismic protection of existing RC buildings

In the field of the seismic protection of buildings, the use of steel plate shear walls (SPSWs) may be particularly profitable in the seismic retrofitting interventions of existing RC buildings designed for gravity loads only. Some past researches have shown that when traditional full SPSWs are used as bracing devices of framed buildings, they may induce excessive design forces to the surrounding frame members. Therefore, low yield steels (LYS) could be a valuable option to overcome this applicability limit. Nevertheless, the scarce availability on the market of these steels suggests the employment of aluminium alloys and perforated steel plates, which have the benefit of incurring excursions in plastic range already for low stress levels. In this paper, a parametric analysis concerning the use of perforated metal plate shear walls (MPSWs) for seismic upgrading of existing RC framed structures represents a novelty of the research in the retrofitting interventions field. To this purpose, first, some experimental tests have been considered to calibrate a finite element model of the panel devices by using the SeismoStruct software. Subsequently, the proposed FEM model has been used to design the retrofitting systems with either full MPSWs or perforated SPSWs of an existing RC residential five-storey building, designed between the 1960s and 1970s of the last century. Finally, the different retrofitting panel systems examined have been compared to each other in terms of both structural and economic viewpoints, allowing to select the best intervention strategy

Layered map reasoning

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Laboratory tests on hydraulic lime mortar reinforced with jute fibres

Background: Considering the high seismic vulnerability of masonry buildings located in the Italian territory, the implementation of seismic retrofit programs is strongly needed.. With consideration for sustainable interventions, it is evident that the retrofit techniques to protect the historical heritage should be carried out with innovative green compound materials, such as mortars reinforced with natural fibres. Objective: In the current paper, laboratory tests on lime mortars strengthened with raw jute fibres have been performed. Methods: The workability of the fibre-reinforced mixture has been assessed through shaking table tests, and the mechanical resistances of standard specimens have been evaluated by bending and compression tests. Results: Considering the hygroscopic nature of jute, it has been identified that the optimal water/lime ratio and the maximum water percentage are absorbed by jute fibres. From the results, how the spreading of the mixture, which is indicative of the mortar consistency, changes with the water/lime ratio, has been evaluated. From bending tests, the effective behaviour of fibres, which provide a stitching effect of the failure crack in the investigated fibre-reinforced lime mortars, has been observed. Conclusion: Finally, the results of compression tests have shown that the examined fibre-reinforced mortars can be effectively used as building products according to the actual Italian technical code NTC 2018

Large-scale seismic vulnerability and risk of masonry churches in seismic-prone areas: Two territorial case studies

In this paper, seismic vulnerability and risk assessment of two samples of churches, located in Teramo and Ischia island (Naples gulf), both affected by the most recent earthquakes that occurred in Italy, are presented. To this aim, we applied a simplified method particularly suitable for seismic evaluations at a territorial scale, providing a global resulting score to be compared among the cases analyzed. The data obtained allowed us to provide vulnerability maps and a seismic risk index for all the considered churches. In addition, the calculated indexes permit a preliminary health state evaluation of the inspected churches, for ranking the priorities and planning additional in-depth evaluations