4,672 research outputs found

    The SPES project at the INFN-Laboratori Nazionali di Legnaro

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    The SPES Radioactive Ion Beam (RIB) facility is in the construction phase at INFN-LNL. It is based on a dual exit high current Cyclotron, with tunable proton beam energy 35–70MeV and 0.2–0.5 mA, used as proton driver to supply an ISOL system with an UCx Direct Target able to sustain a power of 10 kW. The second exit will be used for applied physics: radioisotope production for medicine and neutrons for material study. The ISOL system will produce neutron-rich radioactive ions by proton induced fission in the UCx target. The expected fission rate in the target is in the order of 1013 fissions per second. The exotic isotopes will be re-accelerated by the ALPI superconducting LINAC at energies of 10AMeV and higher, for masses around A = 130amu, with an expected beam intensity around 107–109 pps. Fast neutron spectra will be produced by the proton beam interaction with a conversion target. A production rate in excess of 1014 n/s is expected. The SPES project has the aim to provide high intensity and high-quality beams of neutron-rich nuclei as well as to develop an interdisciplinary research center based on the cyclotron proton beam. The status of the project will be presented

    Evaporation Channel as a Tool to Study Fission Dynamics

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    The dynamics of the fission process is expected to affect the evaporation residue cross section because of the fission hindrance due to the nuclear viscosity. Systems of intermediate fissility constitute a suitable environment for testing such hypothesis, since they are characterized by evaporation residue cross sections comparable or larger than the fission ones. Observables related to emitted charged particle, due to their relatively high emission probability, can be used to put stringent constraints on models describing the excited nucleus decay and to recognize the effects of fission dynamics. In this work model simulations are compared with the experimental data collected via the ^{32}S + ^{100}Mo reaction at E_{lab}= 200 MeV. By comparing an extended set of evaporation channel observables the limits of the statistical model and the large improvement coming by using a dynamical model are evidenced. The importance of using a large angular covering apparatus to extract the observable is stressed. The opportunity to measure more sensitive observables by a new detection device in operation at LNL are also discussed.Comment: v1: 7 pages, 6 figure

    Price Fairness of Processed Tomato Agro-Food Chain: The Italian Consumers' Perception Perspective

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    Food consumers are increasingly searching for emotions and values when purchasing and consuming food. They search for products that ensure social and environmental sustainability, in addition to more common extrinsic product attributes, such as price, packaging, origin, and brand. In particular, there is increasing interest towards product price fairness. The current study aims at exploring consumers’ perception and understanding of price fairness, focusing on the processed tomato products agro-food chain. The study interviewed 832 people. Data were collected through an online questionnaire with the support of Qualtrics software, and data elaboration was carried out with Statistical Package for Social Science (SPSS). The elaboration includes an Exploratory Factor Analysis (EFA) to identify existing latent factors in the consumers’ perception of enabling agro-food system elements influencing farmers’ reception of fair prices. Then, factor mean values were cross-analysed with socio-economic characteristics and processed tomato consumption habits with Analysis of Variance (ANOVA). Results support the idea that consumers are limitedly aware of the processed tomato agro-food chain dynamics and consider farmers as the most unfairly remunerated partner. Women and frequently purchasing consumers of processed tomato products believe farmers should be treated more fairly. There is a difference between what consumers perceive as fair price distribution and actual price distribution among processed tomato chain actors. Further studies may focus on how fairness attribute impacts on consumer purchasing behaviour

    High performance parallel numerical methods for Volterra equations with weakly singular kernels

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    Non-stationary discrete time waveform relaxation methods for Abel systems of Volterra integral equations using fractional linear multistep formulae are introduced. Fully parallel discrete waveform relaxation methods having an optimal convergence rate are constructed. A significant expression of the error is proved, which allows us to estimate the number of iterations needed to satisfy a prescribed tolerance and allows us to identify the problems where the optimal methods offer the best performance. The numerical experiments confirm the theoretical expectations

    Caspase-independent programmed cell death triggers Ca2PO4 deposition in an in vitro model of nephrocalcinosis

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    We provide evidence of caspase-independent cell death triggering the calcification process in GDNF-silenced HK-2 cells

    Prioritized motion-force control of constrained fully-actuated robots: "Task Space Inverse Dynamics"

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    Pre-print submitted to "Robotics and Autonomous Systems"We present a new framework for prioritized multi-task motion-force control of fully-actuated robots. This work is established on a careful review and comparison of the state of the art. Some control frameworks are not optimal, that is they do not find the optimal solution for the secondary tasks. Other frameworks are optimal, but they tackle the control problem at kinematic level, hence they neglect the robot dynamics and they do not allow for force control. Still other frameworks are optimal and consider force control, but they are computationally less efficient than ours. Our final claim is that, for fully-actuated robots, computing the operational-space inverse dynamics is equivalent to computing the inverse kinematics (at acceleration level) and then the joint-space inverse dynamics. Thanks to this fact, our control framework can efficiently compute the optimal solution by decoupling kinematics and dynamics of the robot. We take into account: motion and force control, soft and rigid contacts, free and constrained robots. Tests in simulation validate our control framework, comparing it with other state-of-the-art equivalent frameworks and showing remarkable improvements in optimality and efficiency

    RELAP5-3D thermal hydraulic analysis of the target cooling system in the SPES experimental facility

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    The SPES (Selective Production of Exotic Species) experimental facility, under construction at the Italian National Institute of Nuclear Physics (INFN) Laboratories of Legnaro, Italy, is a second generation Isotope Separation On Line (ISOL) plant for advanced nuclear physic studies. The UCx target-ion source system works at temperature of about 2273 K, producing a high level of radiation (10^5 Sv/h), for this reason a careful risk analysis for the target chamber is among the major safety issues. In this paper, the obtained results of thermofluid-dynamics simulations of accidental transients in the SPES target cooling system are reported. The analysis, performed by using the RELAP5-3D 2.4.2 qualified thermal-hydraulic system code, proves good safety performance of this system during different accidental conditions

    Prioritized Optimal Control

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    Pre-print of the paper presented at Robotics and Automation (ICRA), IEEE International Conference on, Hong Kong, China, 2014This paper presents a new technique to control highly redundant mechanical systems, such as humanoid robots. We take inspiration from two approaches. Prioritized control is a widespread multi-task technique in robotics and animation: tasks have strict priorities and they are satisfied only as long as they do not conflict with any higher-priority task. Optimal control instead formulates an optimization problem whose solution is either a feedback control policy or a feedforward trajectory of control inputs. We introduce strict priorities in multi-task optimal control problems, as an alternative to weighting task errors proportionally to their importance. This ensures the respect of the specified priorities, while avoiding numerical conditioning issues. We compared our approach with both prioritized control and optimal control with tests on a simulated robot with 11 degrees of freedom

    Partial Force Control of Constrained Floating-Base Robots

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    Pre-print of paper presented at Intelligent Robots and Systems (IROS 2014), IEEE International Conference on, Chicago, USA, 2014Legged robots are typically in rigid contact with the environment at multiple locations, which add a degree of complexity to their control. We present a method to control the motion and a subset of the contact forces of a floating-base robot. We derive a new formulation of the lexicographic optimization problem typically arising in multitask motion/force control frameworks. The structure of the constraints of the problem (i.e. the dynamics of the robot) allows us to find a sparse analytical solution. This leads to an equivalent optimization with reduced computational complexity, comparable to inverse-dynamics based approaches. At the same time, our method preserves the flexibility of optimization based control frameworks. Simulations were carried out to achieve different multi-contact behaviors on a 23-degree-offreedom humanoid robot, validating the presented approach. A comparison with another state-of-the-art control technique with similar computational complexity shows the benefits of our controller, which can eliminate force/torque discontinuities
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