| 11. |
- Iucci, Alessandro, et al.
(författare)
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Explainable Reinforcement Learning for Human-Robot Collaboration
- 2021
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Ingår i: 2021 20Th International Conference On Advanced Robotics (ICAR). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 927-934
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Konferensbidrag (refereegranskat)abstract
- Reinforcement learning (RL) is getting popular in the robotics field due to its nature to learn from dynamic environments. However, it is unable to provide explanations of why an output was generated. Explainability becomes therefore important in situations where humans interact with robots, such as in human-robot collaboration (HRC) scenarios. Attempts to address explainability in robotics usually are restricted to explain a specific decision taken by the RL model, but not to understand the complete behavior of the robot. In addition, the explainability methods are restricted to be used by domain experts as queries and responses are not translated to natural language. This work overcomes these limitations by proposing an explainability solution for RL models applied to HRC. It is mainly formed by the adaptation of two methods: (i) Reward decomposition gives an insight into the factors that impacted the robot's choice by decomposing the reward function. It further provides sets of relevant reasons for each decision taken during the robot's operation; (ii) Autonomous policy explanation provides a global explanation of the robot's behavior by answering queries in the form of natural language, thus making understandable to any human user. Experiments in simulated HRC scenarios revealed an increased understanding of the optimal choices made by the robots. Additionally, our solution demonstrated as a powerful debugging tool to find weaknesses in the robot's policy and assist in its improvement.
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| 12. |
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| 13. |
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| 14. |
- Jonsson, Ulf, et al.
(författare)
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Determination of viscosities of oil-refrigerant mixtures at equilibrium by means of film thickness measurements
- 1993
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Ingår i: ASHRAE Transactions. - 0001-2505. ; 99:2, s. 1129-1136
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Tidskriftsartikel (refereegranskat)abstract
- To be able to measure the actual film thickness in a bearing contact lubricated with oil-refrigerant mixtures, a test rig has been designed where the film thickness can be measured by optical interferometry. By calculating backward from the measured film thickness, it is possible to calculate the effective viscosity. The test rig was used to measure the effective viscosity of a polyol ester together with R-134a as a function of temperature and pressure. This paper includes comparisons between viscosity calculated from measured film thickness and viscosity measured with an oscillating bob viscometer. The apparatus was also used for investigating the effect of film thickness of flow rate and sudden changes in pressure.
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| 15. |
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| 16. |
- Kamara, S., et al.
(författare)
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In-Plane Magnetic Anisotropy and Temperature Dependence of Switching Field in (Ga, Mn)As Ferromagnetic Semiconductors
- 2012
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Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 12:6, s. 4868-4873
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Tidskriftsartikel (refereegranskat)abstract
- We explore the magnetic anisotropy of GaMnAs ferromagnetic semiconductor by Planar Hall Effect (PHE) measurements. Using low magnitude of applied magnetic field (i.e., when the magnitude H is smaller than both cubic Hc and uniaxial Hu anisotropy field), we have observed various shapes of applied magnetic field direction dependence of Planar Hall Resistance (PHR). In particular, in two regions of temperature. At T TC/2 the “zigzag-shape” signal of PHR. They reflect different magnetic anisotropy and provide information about magnetization reversal process in GaMnAs ferromagnetic semiconductor. The theoretical model calculation of PHR based on the free energy density reproduces well the experimental data. We report also the temperature dependence of anisotropy constants and magnetization orientations. The transition of easy axis from biaxial to uniaxiale axes has been observed and confirmed by SQUID measurements.
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| 17. |
- Leitman, David I, et al.
(författare)
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Getting the Cue : Sensory Contributions to Auditory Emotion Recognition Impairments in Schizophrenia.
- 2008
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Ingår i: Schizophrenia Bulletin. - : Oxford University Press (OUP). - 0586-7614 .- 1745-1701. ; 36:3, s. 545-556
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Tidskriftsartikel (refereegranskat)abstract
- Individuals with schizophrenia show reliable deficits in the ability to recognize emotions from vocal expressions. Here, we examined emotion recognition ability in 23 schizophrenia patients relative to 17 healthy controls using a stimulus battery with well-characterized acoustic features. We further evaluated performance deficits relative to ancillary assessments of underlying pitch perception abilities. As predicted, patients showed reduced emotion recognition ability across a range of emotions, which correlated with impaired basic tone matching abilities. Emotion identification deficits were strongly related to pitch-based acoustic cues such as mean and variability of fundamental frequency. Whereas healthy subjects' performance varied as a function of the relative presence or absence of these cues, with higher cue levels leading to enhanced performance, schizophrenia patients showed significantly less variation in performance as a function of cue level. In contrast to pitch-based cues, both groups showed equivalent variation in performance as a function of intensity-based cues. Finally, patients were less able than controls to differentiate between expressions with high and low emotion intensity, and this deficit was also correlated with impaired tone matching ability. Both emotion identification and intensity rating deficits were unrelated to valence of intended emotions. Deficits in both auditory emotion identification and more basic perceptual abilities correlated with impaired functional outcome. Overall, these findings support the concept that auditory emotion identification deficits in schizophrenia reflect, at least in part, a relative inability to process critical acoustic characteristics of prosodic stimuli and that such deficits contribute to poor global outcome.
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| 18. |
- Paul, Jan, et al.
(författare)
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Spin and electron distributions in heme-cyanide models and hemeproteins
- 1985
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Ingår i: Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology. - : Elsevier BV. - 0167-4838 .- 1879-2588. ; 832:3, s. 265-273
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Tidskriftsartikel (refereegranskat)abstract
- Proton NMR spectra of low-spin Fe(III) cyanoprotoheme as prosthetic group in a number of proteins are presented. The diagonally positioned 1-, 5- and 3-, 8-methyl groups obey shifts proportional to the Fe(III)/(II) reduction potential Em7, which indicates a pseudo-contact interaction. The correlation with Em7 is understandable if one postulates an enhanced rhombic distortion, dominating the Fe-methyl dipolar interactions. Hatree-Fock-Slater quantum chemical calculations show no significant changes of spin density as a function of the Fe-L5 distance, except at the iron atom and predominantly in the 3dxz and 3dyz orbitals. 4p orbitals, on the other hand, uphold most of the changes of electron density. We also observe a principal difference in the amino acid sequences in the heme-accommodating pocket of oxygen carriers and two-electron transmitters.
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| 19. |
- Santos, Olga, et al.
(författare)
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Whey protein adsorption onto steel surfaces - effect of temperature, flow rate, residence time and aggregation
- 2006
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774. ; 74:4, s. 468-483
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Tidskriftsartikel (refereegranskat)abstract
- Whey protein adsorption on stainless steel surfaces was investigated by in situ ellipsometry under well-defined flow conditions and protein solution residence times. The size distribution in solution of the protein aggregates formed under the same conditions was determined by dynamic light scattering. The adsorption was performed at 72 degrees C and 85 degrees C which is below and above the unfolding temperature of beta-lactoglobulin (75 degrees C). The effect of increasing the Reynolds number on the aggregation process was evident only for the longest protein solution residence time, when larger aggregates were produced. At the higher temperature, higher flow turbulence decreased the amount of protein adsorbed on the surface, which was attributed to shear-induced removal of protein from the surface. At both temperatures, longer protein solution residence times decreased both the adsorption kinetics and the amount of protein adsorbed. This could be related to the concentration of native protein available in solution. Based on the experimental results, a model of the formation of a protein monolayer and multilayers on solid surfaces was developed. The model takes into account the dependence of the adsorption process on both protein solution residence time and flow rate and predicts the evolution of adsorbed mass of protein per unit surface area with operating time. Surface-induced aggregation was identified as the main mechanism responsible for the formation of multilayers, based on experimental data. To reduce the amount of protein adsorbed/deposited on the surface an increase in protein solution residence time was found to be more effective than an increase in the Reynolds number. (c) 2005 Elsevier Ltd. All rights reserved.
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| 20. |
- Santos, Paolo, et al.
(författare)
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First-principles calculations of iron-hydrogen reactions in silicon
- 2018
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 123:24
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Tidskriftsartikel (refereegranskat)abstract
- Controlling the contamination of silicon materials by iron, especially dissolved interstitial iron (Fe-i), is a longstanding problem with recent developments and several open issues. Among these, we have the question whether hydrogen can assist iron diffusion or if significant amounts of substitutional iron (Fe-s) can be created. Using density functional calculations, we explore the structure, formation energies, binding energies, migration, and electronic levels of several FeH complexes in Si. We find that a weakly bound FeiH pair has a migration barrier close to that of isolated Fe-i and a donor level at E-v + 0.5 eV. Conversely, FeiH2 (0/+) is estimated at E-v + 0.33 eV. These findings suggest that the hole trap at E-v + 0.32 eV obtained by capacitance measurements should be assigned to FeiH2 . FesH-related complexes show only deep acceptor activity and are expected to have little effect on minority carrier life-time in p-type Si. The opposite conclusion can be drawn for n-type Si. We find that while in H-free material Fe i defects have lower formation energy than Fe-s , in hydrogenated samples Fe-s -related defects become considerably more stable. This would explain the observation of an electron paramagnetic resonance signal attributed to a FesH-related complex in hydrogenated Si, which was quenched from above 1000 degrees C to iced-water temperature.
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