Development of Ag-Sheathed Bi(2223) Tapes with Improved Microstructure and Homogeneity

The development of the fabrication process of Ag-sheathed Bi(2223) tapes has been carried out in order to improve their transport and mechanical properties, as required by the power applications which are so far under study. Critical current density values of 28 kA/cm² at 77 K have been achieved on long multifilamentary Bi(2223) tapes, with a fabrication process that has been successfully employed in the fabrication of samples longer than 50 m. The microstructure and homogeneity of Ag-sheathed multifilamentary Bi(2223) tapes has been markedly improved by employing an alternative deformation technique. In a substantial part of the fabrication process, swaging, drawing, and rolling have been replaced by deformation with an active turks-head machine, which allows the deformation of rectangular shaped wires. At present, critical current densities in excess of 25 kA/cm² at 77 K have been achieved on long samples prepared with this technique. Moreover, innovative filament configurations have been employed for the fabrication of square-shaped Bi(2223) wires with reduced anisotropy and with critical current densities exceeding 20 kA/cm² at 77 K.     

A co-synthesis approach to embedded system design automation

Embedded systems are targeted for specific applications under constraints on relative timing of their actions. For such systems, the use of pre-designed reprogrammable components such as microprocessors provides an effective way to reduce system cost by implementing part of the functionality as a program running on the processor. However, dedicated hardware is often necessary to achieve the requisite timing performance. Analysis of timing constraints is, therefore, key to determination of an efficient hardware-software implementation. In this paper, we present a methodology for embedded system design as a co-synthesis of interacting hardware and software components. We present a decomposition of the co-synthesis problem into sub-problems, that is useful in building a framework for embedded system CAD. In particular, we present operation-level timing constraints and develop the notion of satisfiability of constraints by a given implementation both in the deterministic and probabilistic sense. Constraint satisfiability analysis is then used to define hardware and software portions of functionality. We describe algorithms and techniques used in developing a practical co-synthesis framework, vulcan. Examples are presented to show the utility of our approach.     

Acute renal replacement in the intensive care unit: now and tomorrow

Although acute renal failure (ARF) requiring dialysis affects only approximately 4% to 7% of patients admitted to the ICU, such individuals tend to be the sickest and most challenging patients in the ICU. The presence of ARF dramatically complicates their care and mandates the use of extracorporeal renal replacement therapy (RRT). The use of such therapy, with its technical and physiological demands, further complicates treatment. Not surprisingly, therefore, several controversies surround the management of these patients: the techniques of RRT, the indications and timing for their application, the intensity of their use, the selection of suitable patients, the nature of appropriate monitoring and physiologic targets for their application, the type of specialist best suited for the daily management of such patients, the cost-effectiveness of RRT, and the expansion of its use to treat patients without ARF. In many ways, the response to these controversies has diverged between Europe, Australia, and New Zealand on the one hand, and the United States on the other. In this article, we illustrate these sometimes quite different philosophies by presenting two perspectives (from Australia and the United States) on a number of important issues pertaining to RRT.     

MAGFET based current sensing for power integrated circuit

A new on-chip non-invasive integrated current sensing, compatible with standard CMOS technology, has been developed, using a 1.2 μm BiCMOS ALCATEL technology, to sense the current in the drain side of a power MOSFET. The circuit is based on a split-drain magnetic sensor, implemented on the same chip of an integrated gate driver for a power MOSFET. A CMOS biasing circuit with a differential current output is also developed. The simulation results of the current sensing show a conversion gain of 1.25 mV/mT.     

Ru/MgO Sol-Gel Prepared Catalysts for Ammonia Synthesis

A new method of preparation of alkali-promoted Ru/MgO catalysts, based on a sol-gel procedure, starting from magnesium ethoxide, Ru₃(CO)₁₂ and a cesium compound has been designed. The gels were subjected to an activation/reduction procedure to substantially obtain Ru-CsOH/MgO. The activated catalysts were tested in ammonia synthesis at atmospheric pressure. It was clear that the sol-gel prepared Cs-promoted Ru/MgO catalysts are much more active, under the same reaction conditions, than the analogous catalysts prepared by impregnation procedures.     

Supporting control definition in programming languages

The paper is devoted to illustrate a new approach to control definition in programming languages. The DIL system developed by the authors to allow a user to define and utilize his own control mechanisms in program design and construction is presented. The motivations of the proposal are discussed in the frame of software engineering and abstraction programming. The main features of DIL are introduced in an informal way through a number of examples of increasing complexity. The basic mode of operation of the system is described and an architecture for the implementation of DIL is given. Meaningful sample applications are shown to validate the main features of the language. Promising directions for future research are presented as well. A run-time model of DIL is sketched in the Appendix.     

The “marginal materials” of the river tiber valley—Italy

The building of extensive road networks involves, amongst other things, the need for large amounts of building materials, which must meet special requirements such as quality, quantity and ready availability. Now, however, there is a growing need for alternative or complementary building materials, i.e. of “marginal materials” which are generally easily found very close to large cities. In Latium, and above all in the surroundings of Rome, such marginal materials are being considered for road building in replacement of the traditional “Roman puzzolanas” and alluvial sands that are no longer easily available owing to depletion of sources and to restrictions of various types. This study presents the physico-mechanical characteristics of marginal materials, pointing to the technological processes that may enhance their technical qualities thus making them eligible for replacing traditional materials.     

Molecular dynamics study of a monomeric heme undecapeptide of cytochromec

Summary Molecular dynamics simulations were performed to predict the structure of the monomeric heme-containing peptide microperoxidase-11 (MP-11). The simulations were carried out both in vacuo and in water solvent, taking as starting coordinates those of the corresponding amino acid sequence in the crystal structure of cytochrome c, since the crystallographic structure of MP-11 is not known. The structural data, including the H-bond network, are reported and visualised with the aid of graphical tools. The structure predicted is consistent with what is known experimentally on MP-11. This agreement suggests that molecular dynamics simulations might be useful in the prediction of the catalytic activity or reactivity of microperoxidases.     

Experimental study on anchored bars in R.C. elements with transverse reinforcement

In the present paper, the experimental results of pullout tests on anchorages are presented. The experiments allow for the evaluation of bar-to-concrete slip and splitting crack openings at several points along the anchored bar. Particular attention is devoted to the confining contribution of both transverse reinforcement and concrete cover. Two series of tests have been performed: in the first series, the influence of the confining contribution of transverse bars is studied, while in the second series the confining contribution of the concrete cover is analyzed. In specimens from the first series without transverse reinforcement, a splitting collapse of the anchorage occurred at the onset of the slip at the unloaded end of the anchored bar. The opposite was true for all the other specimens, as the transverse reinforcement percentage was such that a pull-out failure of the anchorage occurred. As the stirrup index of confinement Ω rose, the resultant ultimate bond stress value $\bar \tau $ increased; however, beyond the value Ω_max ≈ 0.05, there was no further significant increase of bond strength. The splitting-crack propagation rate exhibited a bilinear trend, with a faster crack propagation when the load was larger than 50% of the peak load.     

Guest introduction: Some Italian research on real-time systems

This work was partially supported by the Progetto Finalizzato Sistemi Informatici e Calleolo Parallelo of the CNR under grant no. 89.0052.699.