OutFlank Routing: Increasing Throughput in Toroidal Interconnection Networks

We present a new, deadlock-free, routing scheme for toroidal interconnection networks, called OutFlank Routing (OFR). OFR is an adaptive strategy which exploits non-minimal links, both in the source and in the destination nodes. When minimal links are congested, OFR deroutes packets to carefully chosen intermediate destinations, in order to obtain travel paths which are only an additive constant longer than the shortest ones. Since routing performance is very sensitive to changes in the traffic model or in the router parameters, an accurate discrete-event simulator of the toroidal network has been developed to empirically validate OFR, by comparing it against other relevant routing strategies, over a range of typical real-world traffic patterns. On the 16x16x16 (4096 nodes) simulated network OFR exhibits improvements of the maximum sustained throughput between 14% and 114%, with respect to Adaptive Bubble Routing.Comment: 9 pages, 5 figures, to be presented at ICPADS 201

Materials for high energy Li-ion and post Li-ion batteries

L'abstract è presente nell'allegato / the abstract is in the attachmen

The Evolution of Urban Heritage Concept in France, between Conservation and Rehabilitation Programs

Abstract Since the 1852 Haussmann's decree in which, although linked to a modernization programme, the notion of ensemble historique born, France has constantly pursued its innovative vision of "urban heritage", by enacting the 1962 Malraux law on the safeguarding and valorisation of historic centres (1962) and introducing the zones de protection du patrimoine architectural et urbain (1983). Following the guiding principles of the 2002 Solidarity and urban renewal law, the notion of heritage has been integrated into an overall urban vision, including it into town planning tools. This work intends to present this conceptual advancement and its applications in France

Materials for high energy Li-ion and post Li-ion batteries

Lithium-ion batteries (LIBs) are well established energy storage devices for electronic, transportation and renewable-energy applications. Nevertheless, to meet the ever-increasing energy storage demand for electrical mobility and smart grid, future batteries have to guarantee higher energy density and, at the same time, sustainable and cheaper solutions. In this frame anode and cathode materials with higher specific capacity are required. From the cathode side, according to preliminary DFT calculations, carbon nitride (g-C3N4) was selected and investigated as lithium polysulfides trapping agent in Li-S battery, using a double-layer approach. Carbon nitride was synthetized by a simple thermal condensation route using different precursors, with the aim of evaluating the polysulfides trapping ability in relation with morphology and surface chemistry of different g-C3N4 materials. In a second step, g-C3N4 was synthetized from urea at different temperatures showing variations in specific surface area and surface functionalities. In particular, different amounts of pyridinic nitrogen, directly interacting with lithium polysulfides, were detected. In conclusion, carbon nitride obtained from urea at 550 °C resulted to be the best candidate as trapping agent in the double-layer sulphur cathode and the electrode containing carbon nitride demonstrated long cycling performances, for more than 500 cycles, as well as better electrochemical performances at higher C-rates. Concerning the anode electrode, tin oxide-based materials were investigated. Two different strategies were presented in order to limit the rapid capacity fading of tin oxide anode, increasing the reversibility of the conversion reaction and at the same time containing the huge volume expansion. The first strategy was a simple and scalable wet impregnation synthesis, where tin oxide was directly grown on the surface of a commercial carbon black. The final hybrid compound, containing a particularly high amount of SnO2 (30 wt.%), showed a specific capacity higher than 500 mAh g-1 for more than 500 cycles, with a coulombic efficiency of about 99.9 %. These outstanding electrochemical results were correlated to an optimal distribution of small tin oxide nanoparticles directly anchored to C45 surface. The second strategy adopted g-C3N4, already used for the cathode material, as high surface support for tin dioxide growth. In this case, a simple solid-state synthesis was selected, and the SnO2 precursors were directly mixed with carbon nitride. The final hybrid compound showed a final amount of SnO2 of about 90 wt.% and a huge specific surface area able to contain the volume expansion of tin oxide particles during the alloying process. The final compound showed good electrochemical results, presenting a specific capacity of about 500 mAh g-1 for 100 cycles at 1C, and interesting results at higher current regimes. Last but not least all the synthesis approaches studied in this work resulted valid strategies to increase the electrochemical performances while being simple, sustainable and easily up-scalable. References [1] Versaci et al. Solid State Ion. 2020, 346, 115210 [2] Versaci et al. Electrochim. Acta 2021, 367, 137489 [3] Versaci et al. Appl. Mater. Today 2021, 25, 10116

Data Structures for Task-based Priority Scheduling

Many task-parallel applications can benefit from attempting to execute tasks in a specific order, as for instance indicated by priorities associated with the tasks. We present three lock-free data structures for priority scheduling with different trade-offs on scalability and ordering guarantees. First we propose a basic extension to work-stealing that provides good scalability, but cannot provide any guarantees for task-ordering in-between threads. Next, we present a centralized priority data structure based on $k$-fifo queues, which provides strong (but still relaxed with regard to a sequential specification) guarantees. The parameter $k$ allows to dynamically configure the trade-off between scalability and the required ordering guarantee. Third, and finally, we combine both data structures into a hybrid, $k$-priority data structure, which provides scalability similar to the work-stealing based approach for larger $k$, while giving strong ordering guarantees for smaller $k$. We argue for using the hybrid data structure as the best compromise for generic, priority-based task-scheduling. We analyze the behavior and trade-offs of our data structures in the context of a simple parallelization of Dijkstra's single-source shortest path algorithm. Our theoretical analysis and simulations show that both the centralized and the hybrid $k$-priority based data structures can give strong guarantees on the useful work performed by the parallel Dijkstra algorithm. We support our results with experimental evidence on an 80-core Intel Xeon system

The difficult relationship between ruins and modernity: the case study of the Mother Church reconstruction in Salemi (Italy)

Located in the heart of Sicily, Salemi, a town of Arab origin and first capital of Italy, was devastated by the powerful earthquake that struck the Belice Valley in January 1968. From that moment on, its historic centre has long been abandoned; a few restoration works have been carried out as it was preferred to reconstruct affected districts in new sites. Nevertheless, Salemi has generally maintained its medieval structure, still preserving the original attractive landscape of perched village, resulting from security and control needs of an area based on agricultural and pastoral economy. At its highest point, next to the majestic Norman castle, re-erected in the 13th century by Frederick II of Swabia, stands the Mother Church, were acted the architects Alvaro Siza Vieira and Roberto Collova. Their project, drafted in the early 80's, can be considered as an emblematic case of architectural conservation and cultural preservation. Remains have been seen here in their profound value as a testimony to memory, turning them into charming and moving scenery for the new square created around. The designers considered the traumatic event has a starting point for an overhaul of the historic urban core of the city. They founded the project on the idea of "opening and offering" this sacred space to the town, accepting and integrating the earthquake effects into the architectural plans. Starting from this experience of consolidation and architectural restoration, recalling in its expression Ruskin's romantic memory, this work intends to highlight the historical and today's difficult relationship between ruins and modernity, improvement and destruction, conservation and new buildings design

A study for the conservation of the architectural Islamic complex of Xhemal in Delvina (Albania)

Water is a fundamental element for Islamic culture and the need to purify themselves before the prayer and religious celebrations is made in special baths - near mosques - called hammam. The hammam is usually a large public service building, but there are particular types of small dimensions and for the exclusive use of a wealthy family or, as in the case study here presented - related to the Islamic complex of Xhemal in Delvina (Albania) - an integral part of a religious centre. Characterised by a singular complexity, the monumental site of Xhemal is composed of some aboveground tombs, a mosque, a tekke, two türbe, a fountain and a hammam indeed, as well as of ancient tall plants (cypresses and plane trees). The building, already listed by the national Institute for Cultural Monuments of Albania, has been the subject of a study carried out by prof. Valter Shtylla at the end of the 70s and classed as a hammam from the medieval period. Provisionally measured only in its plan, it is today in a state of serious deterioration, while an example of great interest. For this reason and, along with the entire complex, since 2008 it has been an object of study by the University of Bergamo and Enna Kore, within the research group formed by the Milan Polytechnic and the University Ca' Foscari, in the framework of the program “Albania tomorrow” co-funded by the Cariplo Foundation, in collaboration with the municipality of Delvina. The complex has recently been subjected to a complete laser scanning survey in order to develop a well-planned preservation and valorisation programme

Integrated Methodologies for the Analysis and Conservation of the Old Bar (Montenegro): the Case Study of Doge’s Palace

The old town of Bar in Montenegro, a Byzantine settlement rebuilt on the remains of a more ancient town destroyed in the 3rd century during the Roman invasion of Dalmatia, ruled between 1443 and 1571 from the city of Venice and then by the Turks until 1878 is, today, a little over an abandoned village but, at the same time, an extraordinary monument from the past to protect and enhance. Traces of its most glorious past are still recognizable in the ruins and artifacts of daily life become known following recent archaeological excavations. Stari Bar is a site unique, a sort of miracle that fortunately survived the ravages of time and negligence of the men. However, it now runs the risk of being overwhelmed by a frenzy of "intervention" that leaves little room for reflection and that can produce errors, which cannot be remedied in the future. Rather than rebuild a fake medieval city or give way to immobility, risking that the culture of ruin prevail, it is necessary to pursue activities of knowledge, study and promotion allowing local communities (as well as those further afield) to re-appropriate the memory of those architectural and urban spaces, triggering new ideas for their possible regeneration. In this framework, this paper presents the case study of the "Doge's Palace", analyzing this important monument in depth knowledge, in order to formulate a proposal for its conservation and valorisation. The experience here reported responds to the initial phase of a more ambitious project aiming at producing a three dimensional “picture” of the site in its current state: a representation made both through the documentation of the town’s most relevant parts and the use of virtual tours and 3D modelling. This activity intends to support the nomination proposal submitted by Montenegro in 2010 to include Stari Bar in UNESCO’s World Heritage List