Optimum reliabilities and optimum design

The designer's task is to optimize. Designing for an intuitively fixed reliability is almost as arbitrary as designing for an intuitively fixed safety factor. Efforts to improve the calculation of reliabilities of proposed designs are commendable but sterile unless we take the additional step of optimizing the design reliabilities associated with the various potential limit states. Through examples it is shown how these reliabilities depend on the consequences of entrance into limit states and on the marginal initial cost of the reliability and how earthquake design spectra must differ radically from those for fixed return periods. It is further claimed that the optimum reliabilities depend on how a structure enters a limit state. A more realistic aim is not the establishing of design reliabilities but of optimum designs. This is illustrated in connection with progressive collapse.Mistakes (“human” or “gross” errors) are not considered in the present analysis.     

Textured Tl(1223)/Ag Tapes Prepared by Electrophoretic Deposition

The conventional powder-in-tube technique does not allow to produce textured Tl(1223) tapes. An electrophoretic deposition technique was used to produce uniform layers of controlled thickness on Ag substrates by a simple and reproducible procedure. A high degree of texture, comparable with the one generally observed for Bi-based tapes was obtained thanks to the appropriate grain morphology, by simply alternating deposition and uniaxial pressing. After annealing, critical current densities of 11'000 A/cm² were reached.     

Smoke suppression by ammonium polyphosphate in poly(acrylonitrile) combustion

The influence of ammonium polyphosphate (APP) on the smoke emission of poly(acrylonitrile) (PAN) has been examined, and its mechanism of action as a smoke suppressant agent has been investigated. Smoke density and corresponding residual char data, as a function of temperature, were obtained in order to characterize the smoke propensity of PAN. The amount of generated smoke, both in smoldering and flaming conditions, was considerably lowered by the presence of APP, and higher char yields were obtained. Beside the smoke suppression, flame inhibition effect of APP on PAN was evidenced. Thermogravimetry (TG), oxygen index (OI), and nitrous oxide index (NOI) experiments were also performed. On the basis of our data, APP appears to act as a char-forming agent in PAN combustion. Both smoke suppression and flame inhibition effects can be considered a consequence of this action.     

Methods to Produce Tl(1223) Tapes with Improved Properties

Different methods to prepare superconducting mono- and multifilamentary T1(I223) tapes were developed. High-purity ceramics could be produced by ex-situ or in-situ reaction under a high isostatic gas pressure. Tapes prepared by the PIT method and an in-situ reaction carried out close to the melting point of the oxide were relatively dense and textured. Interesting results were obtained for samples where part of the oxygen atoms in Tl(1223) had been substituted by fluorine. Critical current densities up to 20'000 A/cm² (77 K, 0 T) were reached for tapes produced by the PIT method. Well textured samples were obtained by electrophoretic deposition, the deposited Tl(1223) grains being produced by a synthesis involving substantial melting.     

Smoke dilution methods for the evaluation of the smoke emission from burning polymers: A comparative approach

A comparative approach to the determination of smoke emission from burning polymers has been attempted, and a number of combustion conditions and detection devices have been tried to choose a test method for measuring the smoke proiduction of materials. The combustion apparatus adopted is a hot-air quartz furnace that permits the measured by dynamic method from combustion of PAN, PVC and PVC mixed with some metal oxiders, have been compared with those obtained by an accumulation mode. For PVC the intensity of the light scattered from the evolving smoke has been measured as an alternative to smoke density.     

Macroscopic transport by synthetic molecular machines

Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with-and perform physical tasks in-the macroscopic world represents a significant hurdle for molecular nanotechnology. Here we describe a wholly synthetic molecular system that converts an external energy source (light) into biased brownian motion to transport a macroscopic cargo and do measurable work. The millimetre-scale directional transport of a liquid on a surface is achieved by using the biased brownian motion of stimuli-responsive rotaxanes ('molecular shuttles') to expose or conceal fluoroalkane residues and thereby modify surface tension. The collective operation of a monolayer of the molecular shuttles is sufficient to power the movement of a microlitre droplet of diiodomethane up a twelve-degree incline.     

Discriminating power of the hydrocarbon content from virgin olive oil of extremadura cultivars

Samples of virgin olive oils (105) from seven Extremaduran olive varieties (Cacereña, Carrasqueña, Cornezuelo, Corniche, Morisca, Picual, and Verdial de Badajoz) in three stage of maturity (green, semi-ripe, and ripe) were collected and the alkane, alkene, and sesquiterpene contents determined. There were significant differences at the 0.01 probability level in most of the hydrocarbons, both by variety and by state of maturity. Discriminant analysis applied to 70 samples explained 72.3% of the variance between the different groups of varieties and allowed 90% of the samples to be classified according to their variety. The acceptability of the model was verified against the remaining 35 samples, giving a mean level of correct classification of 94%.     

Development of the design of car bodywork from first concept to prototype

This paper deals with the design of car bodies from the first sketches to the master model, ie to the last stage before mass manufacture. Close scrutiny of the various steps needed in drawing, control and construction make it possible to determine which of them can be replaced by modern automatic procedures.     

Phase-Sensitive Reflective Imaging Device in the mm-wave and Terahertz Regions

Two Free Electron Laser sources have been developed at ENEA-Frascati for a variety of applications: A Compact Free Electron Laser (C-FEL) that provides coherent radiation in the frequency range between 90 and 150 GHz Gallerano et al. (Infrared Phys. and Techn. 40:161, 1999), and a second source, FEL-CATS, which utilizes a peculiar radio-frequency structure to generate coherent emission in the range 0.4 to 0.7 THz Doria et al. (Phys. Rev. Lett 93:264801, 2004). The high peak power of several kW in 15 to 50 ps pulses, makes these sources particularly suitable for the assessment of exposure limits in biological systems and for long range detection. In this paper we present a phase-sensitive reflective imaging device in the mm-wave and THz regions, which has proven to be a valuable tool in the biological Ramundo-Orlando et al. (Bioelectromagnetics 28:587–598, 2007), environmental Doria et al. (2005) and art conservation fields Gallerano et al. (2008). Different setups have been tested at different levels of spatial resolution to image objects from a few centimeter square to larger sizes. Images have been compared to identify and characterize the contrast mechanism.