Numerical and experimental analysis of pure aluminium shear panels with welded stiffeners

In the field of passive seismic protection of framed buildings shear panels can be effectively applied as hysteretic devices. Recently, a wide experimental and numerical study has been undertaken at the University of Naples in order to investigate the behaviour of aluminium alloy stiffened shear panels. Test results show that the proposed system is characterised by a large energy dissipation capacity and therefore is suitable to be used for seismic protection of new and existing framed buildings. To simulate the hysteretic behaviour of the systems, according to the experimental tests, a refined FEM model has been set up. The comparison between experimental and numerical results shows that the adopted model is reliable enough to well interpret a number of important behavioural phenomena in terms of the main global features of the system.     

The influence of tool rotation on an incremental forming process

Incremental forming is a sheet metal forming process characterized by high flexibility; for this reason, it is suggested for rapid prototyping and customised products. On the other hand, this process is slower than traditional ones and requires in-depth studies to know the influence of certain process parameters.The purpose of this study is to investigate the influence of tool rotation on an incremental forming process. Pyramid frusta are created for different speeds and both directions of tool rotation, starting with aluminium alloy sheets; a punch with hemispherical head is used as tool.The variation of speed of tool rotation puts into the variation of friction coefficients, so these ones are preliminarily evaluated for different speeds, in order to explain the influence of tool rotation in terms of forming forces, temperatures reached and surface roughness. The evaluation of these quantities highlights the influence of tool rotation, both in terms of speed and direction of rotation, on the components of the forming forces in the sheet plane, whereas neither the heating of the sheet caused by the friction nor the surface finishing feel the effects of this parameter significantly.     

Prolonged muscular flaccidity: frequency and association with unilateral spatial neglect after stroke

A 21-month-old infant developed coma with hypotonia during a viral infection. Acyl CoA dehydrogenase deficiency was diagnosed on the basis of results of the chromatographic study of organic acids performed on a urine specimen collected during the acute episode. However, other disorders of mitochondrial and fatty acid oxygenation can generate similar symptoms. Emphasis is put on the need for collecting urine specimens in patients who develop alterations in consciousness and hypoglycemia without ketonuria during prolonged fasting or repeated vomiting due to a viral infection. Urine chromatography can suggest which enzyme is defective, although the diagnosis should always be confirmed by a study of fatty acid oxygenation in lymphocytes or fibroblasts.     

Risk assessment for chemical pickling of metals contaminated by radioactive materials

In recent years, many cases of contamination of metal scraps by unwanted radioactive materials have occurred. Moreover, international organisations are evaluating the possibility to re-use or to recycle metals coming from nuclear power plants. The metal recycling industry has started to worry about radiation exposure of workers that could be in contact with contaminated metals during each manufacturing phase. Risks are strongly dependent on the radiation source features. The aim of this study is to perform risk assessment for workers involved in chemical pickling of steel coils. Monte Carlo simulations have been performed, using the MCNP package and considering coils contaminated with (60)Co, (137)Cs, (241)Am and (226)Ra. Under the most conservative conditions (coil contaminated with 1.0 kBq g(-1) of (60)Co), the dose assessment results lower than the European dose limit for the population (1 mSv y(-1)), considering a maximum number of 10 contaminated coils handled per year. The only exception concerns the case of (241)Am, for which internal contamination could be non- negligible and should be verified in the specific cases. In every case, radiation exposure risk for people standing at 50 m from the coil is widely <1 mSv y(-1).     

The Role of the Choroid in Stargardt Disease

Stargardt disease is the commonest juvenile macular dystrophy. It is caused by genetic mutations in the ABCA4 gene. Diagnosis is not always straightforward, and various phenocopies exist. Late-onset disease can be misdiagnosed with age-related macular disease. A correct diagnosis is particularly critical because of emergent gene therapies. Stargardt disease is known to affect retinal pigment epithelium and photoreceptors. Many studies have also highlighted the importance of the choroid in the diagnosis, pathophysiology, and progression of the disease. The choroid is in an integral relationship with the retinal pigment epithelium and photoreceptors, and its possible involvement during the disease should be considered. The purpose of this review is to analyze the current diagnostic tools for choroidal evaluation and the extrapolation of useful data for ophthalmologists and researchers studying the disease.     

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.     

On the bending behaviour and the failure mechanisms of grid-reinforced aluminium foam cylinders by using an experimental/numerical approach

The International Journal of Advanced Manufacturing Technology - Metal foams are attracting interest in both aerospace and automotive industries due to their intriguing properties such as high...