| 1. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Candelario, Victor M., et al.
(författare)
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Aqueous colloidal processing of nano-SiC and its nano-Y3Al5O12 liquid-phase sintering additives with carbon nanotubes
- 2015
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 35:13, s. 3363-3368
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanotubes (CNTs) have occasionally been observed to benefit the aqueous colloidal processing of nano-SiC with its nano-Y3Al5O12 liquid-phase-sintering additives. Experimental evidence is here presented for a broad set of CNTs with different morphology and/or surface functionalization confirming that CNTs (7 vol.% addition), regardless of their features, prevent the coagulation of these nanoceramic suspensions, whence it is inferred that aqueous colloidal processing is well-suited for the environmentally friendly preparation of the homogeneous mixtures of nanoceramic particles and CNTs required for the fabrication of CNT-reinforced ceramic matrix nanocomposites. Furthermore, it is shown that surface-functionalized CNTs seem to work better than deflocculated CNTs for the preparation of stable concentrated colloidal suspensions, whose rheological properties are in general very close, but with thinner CNTs being nonetheless preferable. Finally, the feasibility is demonstrated of fabricating SiC/CNT nanocomposites by aqueous colloidal processing followed by liquid-phase assisted spark-plasma sintering.
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| 3. |
- Candelario, Victor M., et al.
(författare)
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Liquid-phase assisted spark-plasma sintering of SiC nanoceramics and their nanocomposites with carbon nanotubes
- 2017
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 37:5, s. 1929-1936
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Tidskriftsartikel (refereegranskat)abstract
- The appropriate conditions for liquid-phase assisted spark-plasma sintering (SPS) were identified for the fabrication of both SiC nanoceramics and their nanocomposites with carbon nanotubes (CNTs). A parametric study of the nanoceramics and nanocomposites with a given type of CNTs showed that the SPS temperature (as measured by the radial optical pyrometer) optimizing their densification, nanograin size, and mechanical properties is 1700 degrees C (soaking for a few minutes), below which there is incomplete densification, and above which there is obvious grain growth with no benefit in hardness or toughness in the case of the nanoceramics, and prejudicial to both properties in the case of the nanocomposites due to the CNT degradation. It was also shown that the nanocomposites have smaller nanograins than their nanoceramic counterparts, and are softer but tougher. Extension to nanocomposites with different types of CNTs confirmed these trends, and showed that the CNT features do not condition the densification, microstructure or mechanical properties of these nanocomposites.
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| 4. |
- Antanas, Laura, et al.
(författare)
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Semantic and geometric reasoning for robotic grasping : a probabilistic logic approach
- 2019
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Ingår i: Autonomous Robots. - : Springer. - 0929-5593 .- 1573-7527. ; 43:6, s. 1393-1418
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Tidskriftsartikel (refereegranskat)abstract
- While any grasp must satisfy the grasping stability criteria, good grasps depend on the specific manipulation scenario: the object, its properties and functionalities, as well as the task and grasp constraints. We propose a probabilistic logic approach for robot grasping, which improves grasping capabilities by leveraging semantic object parts. It provides the robot with semantic reasoning skills about the most likely object part to be grasped, given the task constraints and object properties, while also dealing with the uncertainty of visual perception and grasp planning. The probabilistic logic framework is task-dependent. It semantically reasons about pre-grasp configurations with respect to the intended task and employs object-task affordances and object/task ontologies to encode rules that generalize over similar object parts and object/task categories. The use of probabilistic logic for task-dependent grasping contrasts with current approaches that usually learn direct mappings from visual perceptions to task-dependent grasping points. The logic-based module receives data from a low-level module that extracts semantic objects parts, and sends information to the low-level grasp planner. These three modules define our probabilistic logic framework, which is able to perform robotic grasping in realistic kitchen-related scenarios.
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| 5. |
- Houard, Aurélien, et al.
(författare)
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Laser-guided lightning
- 2023
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Ingår i: Nature Photonics. - : Springer Nature. - 1749-4885 .- 1749-4893. ; 17:3, s. 231-235
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Tidskriftsartikel (refereegranskat)abstract
- Lightning discharges between charged clouds and the Earth's surface are responsible for considerable damages and casualties. It is therefore important to develop better protection methods in addition to the traditional Franklin rod. Here we present the first demonstration that laser-induced filaments-formed in the sky by short and intense laser pulses-can guide lightning discharges over considerable distances. We believe that this experimental breakthrough will lead to progress in lightning protection and lightning physics. An experimental campaign was conducted on the Santis mountain in north-eastern Switzerland during the summer of 2021 with a high-repetition-rate terawatt laser. The guiding of an upward negative lightning leader over a distance of 50 m was recorded by two separate high-speed cameras. The guiding of negative lightning leaders by laser filaments was corroborated in three other instances by very-high-frequency interferometric measurements, and the number of X-ray bursts detected during guided lightning events greatly increased. Although this research field has been very active for more than 20 years, this is the first field-result that experimentally demonstrates lightning guided by lasers. This work paves the way for new atmospheric applications of ultrashort lasers and represents an important step forward in the development of a laser based lightning protection for airports, launchpads or large infrastructures. A terawatt laser filament is shown to be able to guide lightning over a distance of 50 m in field trials on the Santis mountain in the Swiss Alps.
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| 6. |
- Moldovan, Bogdan, et al.
(författare)
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Relational affordances for multiple-object manipulation
- 2018
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Ingår i: Autonomous Robots. - : Springer. - 0929-5593 .- 1573-7527. ; 42:1, s. 19-44
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Tidskriftsartikel (refereegranskat)abstract
- The concept of affordances has been used in robotics to model action opportunities of a robot and as a basis for making decisions involving objects. Affordances capture the interdependencies between the objects and their properties, the executed actions on those objects, and the effects of those respective actions. However, existing affordance models cannot cope with multiple objects that may interact during action execution. Our approach is unique in that possesses the following four characteristics. First, our model employs recent advances in probabilistic programming to learn affordance models that take into account (spatial) relations between different objects, such as relative distances. Two-object interaction models are first learned from the robot interacting with the world in a behavioural exploration stage, and are then employed in worlds with an arbitrary number of objects. The model thus generalizes over both the number of and the particular objects used in the exploration stage, and it also effectively deals with uncertainty. Secondly, rather than using a (discrete) action repertoire, the actions are parametrised according to the motor capabilities of the robot, which allows to model and achieve goals at several levels of complexity. It also supports a two-arm parametrised action. Thirdly, the relational affordance model represents the state of the world using both discrete (action and object features) and continuous (effects) random variables. The effects follow a multivariate Gaussian distribution with the correlated discrete variables (actions and object properties). Fourthly, the learned model can be employed on planning for high-level goals that closely correspond to goals formulated in natural language. The goals are specified by means of (spatial) relations between the objects. The model is evaluated in real experiments using an iCub robot given a series of such planning goals of increasing difficulty.
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