Search results for "Forming"
showing 10 items of 1719 documents
Design of the Tube Roll Forming Process Through an Heuristic Algorithm
2002
In the paper the design of an industrial tube roll forming process is developed utilizing an heuristic algorithm, namely the simulated annealing (SA). In particular both the number and the shape of the deforming rolls are determined in order to define the forming sequence. The effectiveness of the results supplied by the SA algorithm is verified both by means of some experiments tests carried out on an industrial tube roll forming equipment and through a set of numerical simulations of the process.
Knowledge-Based Systems and F.E. Simulations in Metal-Forming Processes Design An integrated Approach
1991
Summary The automatic computer aided planning and design of cold forming processes includes several phases, among which the most important are the optimal choice of the forming operations sequence and, for each operation, the determination of the more suitable operating parameters. With this aim the Authors propose an integrated approach based on the preliminary choice of some feasible forming sequences, carried out by means of a knowledge-based system, and on the subsequent determination of the optimal one employing a finite element simulation of the process.
Rubber Forming Processes of Thin Sheets
1999
In the last decade flexible media have been increasingly utilized in sheet metal drawing processes in order to reduce the tooling cost and to improve the product quality. In the present paper an axisymmetric deep drawing process of thin steel sheets is taken into account: in particular a flexible pad is utilized in order to simplify the tooling set. The process mechanics is investigated through numerical simulations and experimental tests with the aim to find out a proper set of operative parameters allowing the stamping of sound components and to highlight the particular deformation path of the drawing cup. The comparison between the numerical predictions and the experimental verification …
Macroalgal forest vs sea urchin barren: Patterns of macro-zoobenthic diversity in a large-scale Mediterranean study: Macro-zoobenthos of barren and m…
2020
The study aimed at contributing to the knowledge of alternative stable states by evaluating the differences of mobile and sessile macro-zoobenthic assemblages between sea urchin barrens and macroalgal forests in coastal Mediterranean systems considering a large spatial scale. Six sites (100 s km apart) were selected: Croatia, Montenegro, Sicily (Italy), Sardinia (Italy), Tuscany (Italy), and Balearic Islands (Spain). A total of 531 taxa, 404 mobile and 127 sessile macro-invertebrates were recorded. Overall, 496 and 201 taxa were found in macroalgal forests and in barrens, respectively. The results of this large-scale descriptive study have met the expectation of lower macrofauna complexity …
Signals of loss: Local collapse of neglected vermetid reefs in the western Mediterranean Sea
2022
During the summer of 2022, an extensive die-off of Dendropoma cristatum and other marine organisms associated with vermetid reefs was observed in the western Mediterranean Sea (northern coast of Sicily). Quantitative data from more than 300 km of coastal stripe indicated that the percentage of dead D. cristatum specimens, showing empty and/or transversely fractured shells, ranged from 64 to 84 % in populations having a density of 2900-4730 ind./m2, suggesting that millions of organisms had recently died along the Sicilian coast. This high mortality range coincided with prolonged desiccation events during which biogenic vermetid reefs were exposed to extreme warm-air conditions for several c…
Wharton’s Jelly Mesenchymal Stromal Cells Support the Expansion of Cord Blood–derived CD34+Cells Mimicking a Hematopoietic Niche in a Direct Cell–cel…
2018
Wharton’s jelly mesenchymal stromal cells (WJ-MSCs) have been recently exploited as a feeder layer in coculture systems to expand umbilical cord blood–hematopoietic stem/progenitor cells (UCB-HSPCs). Here, we investigated the role of WJ-MSCs in supporting ex vivo UCB-HSPC expansion either when cultured in direct contact (DC) with WJ-MSCs or separated by a transwell system or in the presence of WJ-MSC–conditioned medium. We found, in short-term culture, a greater degree of expansion of UCB-CD34+cells in a DC system (15.7 ± 4.1-fold increase) with respect to the other conditions. Moreover, in DC, we evidenced two different CD34+cell populations (one floating and one adherent to WJ-MSCs) with …
Theoretical Investigation of Aqueous Phase Reforming of 1,2 Propanediol over a Pt catalyst
2015
Aqueous Phase Reforming (APR) process is one of the most efficient solution for producing hydrogen from biomass renewable feedstocks, such as polyalcohols. [1] Generally the reaction is catalyzed by supported platinoid metals and among these platinum has been recognized as the most active and selective toward the production of hydrogen. However, due to its really high complexity, the reaction mechanism is today poorly understood. DFT methods can be useful for understanding the APR catalytic mechanism at atomistic level. A detailed mechanistic study was carried out using a Pt30 cluster for the modelization of the catalyst and 1,2 propanediol (1,2PDO) as a model feedstock for the APR. Even fo…
DFT investigation of polyalcohols reforming on palladium cluster
2015
Biomass conversion technologies have recently gained high industrial interest for the production of sustainable fuels and fine chemicals; starting feedstocks for these processes are generally complex mixtures of oxygenated compounds, ranging from lignans, carbohydrates and polyalcohols to carboxylic acids [1]. Framed within this scientific context the entire reforming mechanism of two well-known polyols, namely ethylen glycol (C2) and glycerol (C3), on a small Pd cluster was investigated by means of density functional theory. Among the large amount of reaction pathways that can be followed in the reforming of oxygenates, we discuss here only the route that brings to carbon monoxide and hydr…
Injectable hydrogel formulations to host adipose stem cell spheroids for stemness maintenance and bone and cartilage regeneration
2021
Adipose-derived mesenchymal stem cells (ASCs) represent a great promise for tissue regeneration as fat is a very abundant source of stem cells (1) and owing to their ability to self-renew and differentiate into specific tissue types (2). In general, they are usually cultured as two-dimensional (2D) adherent monolayers, not representative of the in vivo condition, often entailing lower cell viability and, more in general, a lower “cell quality” in terms of regenerative potential (3, 4). When ASCs are cultured in low adhesion flasks and with a suitable culture medium, they aggregate in the form of three-dimensional spheroids (SASCs). The incorporation of these spheroids into injectable, in-si…
Paesaggio, piano, progetto: problemi lessicali e altro
2012
The notion of landscape and the techniques for landscape design must necessarily be based on two principal regulatory provisions, the European Landscape Convention and in Italy the law on cultural heritage and landscape. Consideration must also be given to what is meant by the term ‘landscape' in normal and specialist parlance and to the nature of the training of landscape architects, because it is from all this that the ambiguities and misunderstandings that surround the notion of landscape originate. Consideration must also be given to the relations between planning and real and local transformations, because the contents and procedures for the formulation of designs depend on them. Lands…