4,801 research outputs found
The SPES project at the INFN-Laboratori Nazionali di Legnaro
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
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
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
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
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"
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
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
Fuzzy FMECA analysis of radioactive gas recovery system in the SPES experimental facility
Selective Production of Exotic Species is an innovative plant for advanced nuclear physic studies. A radioactive beam, generated by using an UCx target-ion source system, is ionized, selected and accelerated for experimental objects. Very high vacuum conditions and appropriate safety systems to storage exhaust gases are required to avoid radiological risk for operators and people. In this paper, Failure Mode, Effects, and Criticality Analysis of a preliminary design of high activity gas recovery system is performed by using a modified Fuzzy Risk Priority Number to rank the most critical components in terms of failures and human errors. Comparisons between fuzzy approach and classic application allow to show that Fuzzy Risk Priority Number is able to enhance the focus of risk assessments and to improve the safety of complex and innovative systems such as those under consideration
Finite element modeling of microstructural changes in hard machining of SAE 8620
Surface and subsurface microstructural characterization after machining operations is a topic of great interest for both academic and industrial research activities. This paper presents a newly developed finite element (FE) model able to describe microstructural evolution and dynamic recrystallization (DRX) during orthogonal hard machining of SAE 8620 steel. In particular, it predicts grain size and hardness variation by implementing a user subroutine involving a hardness-based flow stress and empirical models. The model is validated by comparing its output with the experimental results available in literature at varying the cutting speed, inser0000-0001-6268-6720t geometry and flank wear. The results show a good ability of the customized model to predict the thermo-mechanical and microstructural phenomena taking place during the selected processes
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