The paper describes the production of an AlSi7Mg cast alloy with Li additions and the reactions of the melt with different moulding materials. It is known that Li is very reactive and tends to form ...various reaction products such as oxides, gases, etc., which can influence the casting quality. The aim of the research was to find a suitable way to produce such an alloy and to describe the reaction products that are formed between the melt and the moulding material and thus to find a suitable moulding material for processing Al cast alloys with Li additions. The melt was produced in an induction furnace under an inert atmosphere. After melting, 1 w/% Li was added and the melt was cast into five different mould materials consisting of graphite, steel, a CO2 sand mixture, Croning mixture and calcium silicate materials. In the last three cases, various alcohol-based coatings were also used, such as graphite, zirconium oxide-graphite coating and aluminate-graphite filler coating. The results showed that the reaction products in the form of powder on the casting surfaces and the gas porosity in the castings occurred in the cast of a calcium silicate mould and sand mould mixtures. In the case of graphite and steel moulds, the casting surfaces were not oxidised, with no reaction products, and no gas porosity.
The paper analyses the debate in Sicily on the construction of the monumental colonnaded porticoes that characterise the facades of public edifices built on the island from the post- Unification ...period to the Fascist regime. The pronao of the Massimo Theatre in Palermo (from 1875) marks the climax of a cultural movement, which, for almost a century, was to associate the neo-Greek style with public buildings and the material of choice of Sicily’s church building tradition in a deterministic manner. Calcarenite was used to build the peristyles of the temples of the archaic and classical age, with imposing, tapered and grooved columns consisting of overlapping sections. In the Fascist period, and in the age of reinforced concrete buildings, the construction of the Court House in Messina (from 1923) became a topic of discussion in the debate at national level. The subsequent use of local materials, some of which of more recent extraction and processing, together with reinforced concrete, contributed to distorting the “archaeological” style of the initial projects sponsored by local authorities, towards modern and abstract compositions, as in the case of the construction of the Post Office Building in Palermo (from 1933), or towards compromise solutions, as in the case of the Court House in Catania (from 1937). The solutions investigated in any case required engineering and technological advances to allow the buildings to achieve a new monumental scale.
The mechanical properties of the composite materials for prosthetic sockets are a key determinant of the quality and usability of prostheses. Our aim was to compare the existing materials used in ...production at our institution with some modified, potentially improved materials. We conducted an industrial experiment. The existing material (A) was compared with three newly produced materials that introduced changes in the lamination process: B1, where an infusion spiral tube was added; B2, where the resin was degassed; and B3, where a mesh and peel ply were used. The specimens underwent laboratory strength testing. The strength measurements were statistically analysed using one-way analysis of covariance (ANCOVA) that was adjusted for specimen thickness because of the observed negative correlation of thickness with strength. Material A had the highest bending strength, on average, but there were no statistically significant differences in the bending strength between the materials after adjusting for the specimen thickness (p = 0.941). Materials B1 and B2 exhibited statistically significantly lower tensile strengths than material A (p < 0.001). Material B3 had the lowest average tensile strength, but it could not be statistically distinguished from the others, because of the significantly larger average specimen thickness. The compressive strength was tested only for materials B1, B2 and B3; their averages did not differ statistically significantly (p = 0.291). Laboratory strength testing provided important insights into the differences between the various laminated composite prosthetics materials. We did not reach our initial goal to produce a better material, but we will continue our research and development in this field with a more systematic, technological approach.
L'articolo affronta due temi strettamente legati tra loro: il deposito legale dei materiali cartografici inItalia e il loro censimento da parte del Bollettino delle pubblicazioni italiane ricevute ...per diritto distampa(1886-1957) e della Bibliografia nazionale italiana(BNI, 1958). Pur costituendo un patrimoniodi straordinario valore storico, artistico e culturale, i materiali cartografici sono stati a lungo trascuratidalla normativa sul deposito legale e il loro censimento da parte del Bollettinoe della Bibliografianazionale italianaè stato per molto tempo irregolare, fino a venire completamente abbandonato neglianni Sessanta del Novecento. L'obbligo di deposito e il censimento, inoltre, hanno riguardato solo lecarte geografiche e gli atlanti, mentre altre tipologie di risorse cartografiche come i globi, i modellitridimensionali e le carte geografiche digitali non sono mai state considerate.
The contribution aims to offer a methodological approach to the investigation of medieval landscapes. Particular attention is devoted to different types of sources (written and material), to their ...respective information potential and to their cross-use in the investigation to settlement systems and their significant elements.
Granular Patterns Aranson, Igor; Tsimring, Lev
2009, 2008-11-01, 2009-03-12
eBook
This book is a systematic introduction to the new and rapidly evolving field of patterns in granular materials. Granular matter is usually defined as a collection of discrete macroscopic solid ...particles (grains) with a typical size large enough that thermal fluctuations are negligible. Despite this seeming simplicity, properties of granular materials set them apart from conventional solids, liquids, and gases due to the dissipative and highly nonlinear nature of forces among grains. The last decade has seen an explosion of interest to nonequilibrium phenomena in granular matter among physicists, both on experimental and theoretical sides. Among these phenomena, one of the most intriguing is the ability of granular matter upon mechanical excitation to form highly ordered patterns of collective motion, such as ripples, avalanches, waves, or bands of segregated materials. This book combines a review of experiments with exposition of theoretical concepts and models introduced to understand the mechanisms of pattern formation in granular materials. The unique feature of this book is a strong effort to extend concepts and ideas developed in granular physics beyond the traditionally defined boundaries of the granular physics towards emergent fields, especially in biology, such as cytoskeleton dynamics, molecular motors transport, ordering of cells and other active (self-propelled) particles, dynamic self-assembly, etc.
The book gives an overview of the dynamic behavior of dislocations and its relation to plastic deformation. It introduces the general properties of dislocations and treats the dislocation dynamics in ...some detail. Finally, examples are described of the processes in different classes of materials, i.e. semiconductors, ceramics, metals, intermetallic materials, and quasicrystals. The processes are illustrated by many electron micrographs of dislocations under stress and by video clips taken during in situ straining experiments in a high-voltage electron microscope showing moving dislocations. Thus, the users of the book also obtain an immediate impression and understanding of dislocation dynamics. TOC:1. Introduction.- 2. Experimental methods.- 3. Properties of dislocations.- 4. Dislocation motion.- 5. Dislocation kinetics, work-hardening and recovery.- 6. Semiconductors.- 7. Ceramic single crystals.- 8. Metallic alloys.- 9. Intermetallic alloys.- 10. Quasicrystals.- 11. Conclusion.
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