1,721,029 research outputs found
Kinematic observations and energy modeling of a Zoz Simoloyer high-energy ball milling device
No full textHigh-energy ball milling is a material-processing method promoting near-room temperature transformations of powder mixtures. Obtained products possess peculiar properties, otherwise difficult or impossible to obtain by using conventional methods. Powder transformation is promoted by energy releases from milling media to trapped powder and the mechanism strongly depends by mechanical characteristics of the milling device. Planetary and horizontal ball mills, attritors, 1D and 3D vibrating apparatus are well-known and utilized in this powder-processing technology. This paper is focused on a ZOZ Simoloyer CM01 horizontal ball milling apparatus; a kinematic model characterizing balls motion and energy released have been found. For the purpose, an experimental setup, based on digital image acquisition, has been constructed and ball trajectories have been caught by using a properly developed software. Using image analysis results, tangential and radial components of balls speed distribution have been assessed and kinetic energies of the impacting balls inside the milling vial have been evaluated. The obtained results permits to evaluate the energy released to the powder during the milling action and to infer some expected consequences on mechanically activated reactions. © Springer-Verlag London 2013
Multi-agent path finding in configurable environments
No full textMulti-Agent Path Finding (MAPF) plays an important role in many real-life applications where autonomous agents must coordinate to reach their goals without collisions. MAPF problems often take place in structured environments that are usually assumed to be static and known in advance. In this paper, we introduce C-MAPF, i.e., MAPF in Configurable environments, a novel variant of the MAPF problem in which the environment is configurable, namely its structure and topology can be controlled within some given constraints. Consider, for instance, a warehouse logistics application: the environment can be changed (at least to some degree) by the managers of the warehouse, for example by re-arranging the positions of the shelves or by removing or adding temporary walls. We study the properties of the C-MAPF problem and we devise two algorithms for solving it, both based on Conflict-Based Search (CBS), a state-of-the-art MAPF algorithm. First, we present Parallel CBS (P-CBS), that searches for a solution by simultaneously considering all the possible configurations of the environment. We then present Abstract CBS (A-CBS), an extended version of the CBS algorithm that solves C-MAPF problems by introducing a new type of conflict on the allowable configurations of the environment. We prove that our solvers are both complete and optimal and we experimentally assess their performance in different settings
Design and Control of a Reclining Chair with Soft Pneumatic Cushions
Full text linkThe object of this work is the control of a reclining chair with active cushions used to optimize the interaction of the human with the chair and to avoid the formation of sores on the skin. The cushion system, already presented in other works, consists of air-cell actuators distributed according to the risk that pressure ulcers on the skin can be generated in certain areas. In this work, four cushions are designed and controlled for four parts of the human body: 1) head; 2) back; 3) buttocks; 4) heels. Cushions are used to design a reclining chair that can be moved between two configuration limits: a) chair; b) bed. The four cushions can provide real-time pressure mapping with closed-loop control, which allows to identify critical points on the body surface where pressure ulcers could form. The control systems for the single air-cell and for all cushions are designed and simulated using the software MATLAB/Simulink, presenting very interesting results
Mechanochemical synthesis of manganese cobalt spinel as interconnector protective coating material. First experimental findings.
No full textIn the frame of an activity oriented on the development and characterization of cells and stacks for the integration in a micro- CHP system, synthesis, formulation and optimization of manganese cobalt spinel for the deposition of protective coatings on interconnector plates have been performed. A description of the process is given. Characterization of spray coated interconnector samples and discussion of the experimental findings are reported. © The Electrochemical Society
Liquid-assisted mechanochemical synthesis of an iron carboxylate Metal Organic Framework and its evaluation in diesel fuel desulfurization
No full textAn iron (III) carboxylate Metal Organic Framework isostructural with MIL-100(Fe) was synthesized through a mechanochemical route. The material, rapidly obtained by liquid-assisted grinding at room temperature, was characterized by X-ray powder diffraction, infrared spectroscopy, scanning electron microscopy, thermal gravimetry, nitrogen physisorption and adsorption microcalorimetry of ammonia. For comparison, the features of a commercial iron trimesate produced via electrochemical route were investigated as well. The ball-milled sample showed better crystallinity, associated with good thermal stability, higher surface area and pore volume. The adsorption performance of both the ball-milled and commercial samples for the ambient-temperature removal of 4,6-dimethyldibenzothiophene (4,6-DMDBT) from 4,6-DMDBT)/n-heptane solutions simulating a diesel fuel was also investigated. The maximum adsorption capacity for the ball-milled sample resulted twice as big as that for the commercial one. An interpretation of the different adsorption behavior is proposed. © 2015 Elsevier Inc. All rights reserved
Modelling, design and control of a new seat-cushion for pressure ulcers prevention
No full textPressure ulcers are a frequent complication in patients having limited activity and mobility (e.g., elderly people, spinal cord injury patients, people with disabilities, etc.). The aim of this work is the conceptual design, modelling and control of a new seat cushion for pressure ulcers prevention. The whole system (constituted by the seat cushion equipped with a real-time pressure mapping with closed-loop control) is designed to identify the critical points on the human skin, before pressure ulcers creation, and to be able to distribute the contact pressure between the human and cushion avoiding wound creation. The seat cushion is constituted by soft air-cells actuated by air flow. To define the shape and size of the soft air-cells, finite element simulations are carried out, analysing the internal volume reduction with external loads application to reproduce the variable stiffness. The data obtained by finite element analysis are used to simulate inflation and deflation of the soft bubble air-cells. Finally, the control systems of a single air-cell and of the whole cushion are designed and simulated. The novelty of our work consists in the conception of a seat cushion able to recognise higher and lower risk zones of pressure ulcer generation on the human skin and to provide compensation automatically. This work can therefore be considered in line with the sustainable development goals recently launched by the EU Commission
Cu-Mn-Co oxides as protective materials in SOFC technology: The effect of chemical composition on mechanochemical synthesis, sintering behaviour, thermal expansion and electrical conductivity
No full textTo study the effect of the composition on the physico-chemical properties of mixed Cu-Mn-Co oxides as SOFC interconnects coating materials, different compounds have been obtained through a High Energy Ball Milling (HEBM) process. The mechanochemical treatment produces highly activated multi-phase powders that easily react at intermediate temperature to form the equilibrium products. Thermogravimetric, dilatometric and in-situ high temperature analyses allowed to show that Copper addition promotes cubic spinel stability at low temperature and enhances sintering behaviour. Dilatometric and conductivity analysis carried out on sintered pellets allowed to obtain simple relations between the materials properties and the composition. Coefficient of Thermal Expansion (CTE) and electrical conductivity are increased by Copper doping and high Co:Mn ratios. These findings suggest that the materials characteristics can be opportunely tuned through appropriate composition design, to simultaneously obtain enhanced sintering behaviour, high electrical conductivity and CTE adapted to match the substrate. © 2016 Elsevier Lt
The effect of chemical composition on high temperature behaviour of Fe and Cu doped Mn-Co spinels
No full textMixed Mn-Co spinels are currently studied as protective coating materials for Solid Oxide Fuel Cells interconnects. Compositional changes in manganese cobaltites lead to modifications in the materials properties, such as sintering behaviour, thermal expansion and electrical conductivity, with advantages in the technological application. In this work, the effect of Fe, Cu and simultaneous Fe+Cu doping of Mn-Co spinels has been studied. Different oxide powder mixtures were prepared with a High Energy Ball Milling (HEBM) treatment, obtaining highly reactive oxides that easily form single spinel phase compounds by moderate heating. The effect of the composition is observed on high temperature stability of the spinel phase and on densification behaviour of the powders, greatly enhanced by copper addition. Analyses carried out on sintered pellets allow to observe simple relations among dopant concentration, thermal expansion and electrical conductivity. The combined effect is obtained in case of the simultaneous addition of multiple dopants. An appropriate composition can be therefore designed to obtain a material characterized by enhanced sintering behaviour, high electrical conductivity and tailored thermal expansion to fulfil the application requirements. © 2016 Elsevier Ltd and Techna Group S.r.l
Magnetic Metal-Organic Framework Composite by Fast and Facile Mechanochemical Process
No full textMagnetic porous metal-organic framework nanocomposite was obtained by an easy, efficient, and environmentally friendly fabrication method. The material consists in magnetic spinel iron oxide nanoparticles incorporated in an iron(III) carboxylate framework. The magnetic composite was fabricated by a multistep mechanochemical approach. In the first step, iron oxide nanoparticles were obtained via ball milling inducing mechanochemical reaction between iron chlorides and NaOH using NaCl as dispersing agent. Magnetic nanoparticles (MNs) were functionalized by neat grinding with benzene-1,3,5-tricarboxylic acid (1, 3, 5 BTC) and were then subjected to liquid assisted milling using hydrated FeCl3, water, and ethanol to obtain a magnetic framework composite (MFC) consisting of iron oxide nanoparticles encapsulated in a MOF matrix. We report, for the first time, the applicability of the grinding method to obtain a magnetic composite of metal-organic frameworks. The synthesized material exhibits magnetic characteristics and high porosity, and it has been tested as carrier for targeted drug delivery studying loading and release of a model drug (doxorubicin). Developed systems can associate therapeutics and diagnostics properties with possible relevant impact for theranostic and personalized patient treatment. Furthermore, the material properties make them excellent candidates for several other applications such as catalysis, sensing, and selective sequestration processes. © 2018 American Chemical Society
Ionic liquid electrolytes for safer and more reliable sodium battery systems
Full text linkNa+-conducting, binary electrolytic mixtures, based on 1-ethyl-3-methyl-imidazolium, trimethyl-butyl-ammonium, and N-alkyl-N-methyl-piperidinium ionic liquid (IL) families, were designed and investigated. The anions were selected among the per(fluoroalkylsulfonyl)imide families. Sodium bis(trifluoromethylsulfonyl)imide, NaTFSI, was selected as the salt. The NaTFSI-IL electrolytes, addressed to safer sodium battery systems, were studied and compared in terms of ionic conductivity and thermal stability as a function of the temperature, the nature of the anion and the cation aliphatic side chain length. Room temperature conductivities of interest for sodium batteries, i.e., largely overcoming 10-4 or 10-3 S cm-1, are displayed. Similar conduction values are exhibited by the EMI-based samples even below -10 °C, making these electrolyte mixtures potentially appealing also for low temperature applications. The NaTFSI-IL electrolytes, with the exception of the FSI-ones, are found to be thermally stable up to 275 °C, depending on the nature of the cation and/or anion, thus extending their applicability above 100 °C and remarkably increasing the reliability and safety of the final device, especially in the case of prolonged overheating
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