Large N.G. explosion and fire involving several buried utility networks

This paper describes an accident (explosion and natural gas fire) that occurred in Turin (Italy), in which power distribution cables, tramway network feeding cables and a gas pipe were involved. The described accident is particularly interesting because it occurred in the town centre and lasted several hours, producing a very high risk for the population. Fortunately, nobody was injured, but 120 people were evacuated for 24 h. The sequence of events is described, the involved facilities are examined and the physical processes which led to the different top events are discussed. Actually, starting from a modest event (600 V electric cable loss of insulation), which most likely lasted for months, the aforementioned accident was reached in a crescendo of domino effects. This sequence has been represented by an ISD in which the failure of the different protection systems is highlighted. These protection systems were mostly based upon the strict respect of procedures both in the installation and in the following maintenance of the different utilities. These aspects have been also briefly devised in the light of Italian and foreign regulations concerning the problem of the coexistence of buried utilities

Progetto e realizzazione di una piattaforma scalabile per la robotica mobile

The main objective of my activity, was to create a mobile platform with a focus on two aspects: teaching and some particular applications in the real world. Regarding education, the fundamental choice has been to develop internally most of the components rather than acquire them from third parties; this choice has encouraged the full knowledge of every single part of the mobot, whether mechanical, hw or sw, leaving open any future development and replication of the system. The result is a device on which you can conduct research in mobile robotics and articial intelligence, enabling students to gain experience in the field of automatic controls at various levels of development: sw, fw, hw and mechanic. As regards the real world applications, special attention was paid to two areas of employ of these devices: the mobot for service (i.e trays door mobot, surveillance staff,...) and assistance to disabled and elderly people. Following are reported some of the main aspects that have characterized SabotOne development. - The name SabotOne Sabot is the acronym for Scalable mobot (i.e mobile robots). The main focus which drive the design of each component, was to create a modular system allowing expandability of mobot. - Machanics The design of the mechanical parts has been made through the 3D-CAD modeling. All the parts were then made from aluminum and assembled to form the entire SabotOne device. The platforms are modular, providing accommodation of the electronics in the lower levels, leaving the higher ones to specific uses depending on field of use of the mobot. The kinematics of the mobot, reects the unicycle physical model which provides mobility of the device even in tight spaces and is very similar to that of wheelchairs for the disabled people. - Electronics It has been designed and realized a board for electrical axis control in position loop. The board can control two direct current motors used in the mobot traction. It was realized firmware and designed the communication protocols in order to make this card appropriate in robotics applications in which it was used. The board has been equipped with signal condition electronic to provide acquisition of sensory signals (A/D converter, GPIO). Moreover, three communication protocols are made available on the board: CAN, TCP/IP (802.11b/g, RJ45) and Modbus on RS485. On the ethernet interface a web server is available to set conguration parameters board, while the serial interface enable the board to exchange information with a smart unit such as an embedded-pc equipped with an operating system. - Software { Development of Sabot Workbench It is a tool that is used to remote monitoring all Sabots connected to a network. It was developed using the modern framework Eclipse Java-RCP. This framework has enabled the modeling of all the features of the Workbench through the paradigm of the plugin. This allows to add functionality to the application without having to modify the application core. { Design of Communication protocol between Workbench and Sabot It is based on Jabber/XMPP protocol and the specification SensML/SWE (designed by Open Geospatial Consor- tium). It is designed to integrate XMPP (used as information carrier) and SensML/SWE that defines the ontologies for describing measurable phenomena and relative sensors. It has been dened the concept of identity of a controlled system and integrated within XMPP protocol. The SensML specification has been extended to support the concept of actuator. The protocol designed, was denoted with the acronym ControlML. { Development of trajectory control, path planning and autolocalization algorithms Path planning has been developed in C++ implementing LPN algorithm. It was built a sim- ulator to verify the algorithm efficiency and completeness. It has seen that the algorithm is complete (can always and a path toward a target qual'ora this exists) and is efficient (planning a course in less than 100ms over a space partitioned into 10.000 cells). The trajectory control was achieved by implementing two different algorithms, the first based on pseudoinversion of dynamic system characterized from non-holonomic constraints, the second conducted by the dy- namic feedback linearization. It was built a simulator to verify the tracking error of controllers and we have seen that both controllers are able to undo the following error. For autolocalization, it has been acquired an inertial platform on which was implemented a Kalman Filter for the \fusion" of various sensory data (accelerometers, gyroscopes and magnetometers). It has seen that the inertial data should have to be \merged" with references to absolute position (feature extracted from images or RFID tag) because of the intrinsic drift of inertial sensors. { Development of SabotSabot smart unit software architecture It has been designed and developed an abstaction of operating system using object oriented paradigm (design pattern) to decouple the application-level from O.S adopted in this application (linux). It has developed an architecture that can realize the concept of run-time plugin by lazy-loading of libraries in linux. In this framework are integrated the algorithms for planning trajectory, for autolocalizing and avoiding obstacle. The communication protocol ControlML takes care to keep in touch the Sabots and the control stations with Workbench. The framework was designed in UML language using strategies oriented to Items and criteria for \Design Pattern" and \Real time design pattern" inertial sensors

Intrinsic and Extrinsic Stability of Ovonic-Switching Devices

The time evolution of current and voltage in Ovonicswitching devices is affected, on one side, by parasitic elements due to contacts and connectors and, on the other one, by the internal-relaxation mechanisms of the material itself. The two aspects, respectively termed here \u201cintrinsic\u201d and \u201cextrinsic\u201d dynamics, are investigated in this paper on the basis of the time-dependent, trap-limited conduction model proposed by the authors for investigating this type of devices

Noisy quantum walks of two indistinguishable interacting particles

We investigate the dynamics of continuous-time two-particle quantum walks on a one-dimensional noisy lattice. Depending on the initial condition, we show how the interplay between particle indistinguishability and interaction determines distinct propagation regimes. A realistic model for the environment is considered by introducing non-Gaussian noise as time-dependent fluctuations of the tunneling amplitudes between adjacent sites. We observe that the combined effect of particle interaction and fast noise (weak coupling with the environment) provides a faster propagation compared to the noiseless case. This effect can be understood in terms of the band structure of the Hubbard model, and a detailed analysis as a function of both noise and system parameters is presented.Comment: 9 pages, 8 figure

Intrinsic Electric Oscillations of Ovonic Devices towards the TeraHerz limit

The time-dependent response of Ovonic devices to an electric potential ramp signal is analysed by means of an enhanced version of a previously published time-dependent charge- transport model proposed by the authors. Depending on the inevitable parasitics of the system, either stable or oscillating solutions are found according to the position of the load line. The model also allows for speculations on the potential of Ovonic materials in the design of high- frequency oscillating circuits close to the terahertz range

Electronic, optical and thermal properties of the hexagonal and fcc Ge2Sb2Te5 chalcogenide from first-principle calculations

We present a comprehensive computational study on the properties of face-centered cubic and hexagonal chalcogenide Ge2Sb2Te5. We calculate the electronic structure using density functional theory (DFT); the obtained density of states (DOS) compares favorably with experiments, also looking suitable for transport analysis. Optical constants including refraction index and absorption coefficient capture major experimental features, aside from an energy shift owed to an underestimate of the band gap that is typical of DFT calculations. We also compute the phonon DOS for the hexagonal phase, obtaining a speed of sound and thermal conductivity in good agreement with the experimental lattice contribution. The calculated heat capacity reaches ~ 1.4 x 106 J/(m3 K) at high temperature, in agreement with experimental data, and provides insight into the low-temperature range (< 150 K), where data are unavailable.Comment: 19 pages, 8 figure

Quantum walks of two interacting particles on percolation graphs

We address the dynamics of two indistinguishable interacting particles moving on a dynamical percolation graph, i.e., a graph where the edges are independent random telegraph processes whose values jump between 0 and 1, thus mimicking percolation. The interplay between the particle interaction strength, initial state and the percolation rate determine different dynamical regimes for the walkers. We show that, whenever the walkers are initially localised within the interaction range, fast noise enhances the particle spread compared to the noiseless case

GPU-accelerated algorithms for many-particle continuous-time quantum walks

Many-particle continuous-time quantum walks (CTQWs) represent a resource for several tasks in quantum technology, including quantum search algorithms and universal quantum computation. In order to design and implement CTQWs in a realistic scenario, one needs effective simulation tools for Hamiltonians that take into account static noise and fluctuations in the lattice, i.e.\ua0Hamiltonians containing stochastic terms. To this aim, we suggest a parallel algorithm based on the Taylor series expansion of the evolution operator, and compare its performances with those of algorithms based on the exact diagonalization of the Hamiltonian or a 4th order Runge\u2013Kutta integration. We prove that both Taylor-series expansion and Runge\u2013Kutta algorithms are reliable and have a low computational cost, the Taylor-series expansion showing the additional advantage of a memory allocation not depending on the precision of calculation. Both algorithms are also highly parallelizable within the SIMT paradigm, and are thus suitable for GPGPU computing. In turn, we have benchmarked 4 NVIDIA GPUs and 3 quad-core Intel CPUs for a 2-particle system over lattices of increasing dimension, showing that the speedup provided by GPU computing, with respect to the OPENMP parallelization, lies in the range between 8x and (more than) 20x, depending on the frequency of post-processing. GPU-accelerated codes thus allow one to overcome concerns about the execution time, and make it possible simulations with many interacting particles on large lattices, with the only limit of the memory available on the device. Program summary Program Title: cuQuWa Licensing provisions: GNU General Public License, version 3 Program Files doi: http://dx.doi.org/10.17632/vjpnjgycdj.1 Programming language: CUDA C Nature of problem: Evolution of many-particle continuous-time quantum-walks on a multidimensional grid in a noisy environment. The submitted code is specialized for the simulation of 2-particle quantum-walks with periodic boundary conditions. Solution method: Taylor-series expansion of the evolution operator. The density-matrix is calculated by averaging multiple independent realizations of the system. External routines: cuBLAS, cuRAND Unusual features: Simulations are run exclusively on the graphic processing unit within the CUDA environment. An undocumented misbehavior in the random-number generation routine (cuRAND package) can corrupt the simulation of large systems, though no problems are reported for small and medium-size systems. Compiling the code with the -arch=sm_30 flag for compute capability 3.5 and above fixes this issue