2,577 research outputs found
On fractional Choquard equations
We investigate a class of nonlinear Schrodinger equations with a generalized
Choquard nonlinearity and fractional diffusion. We obtain regularity,
existence, nonexistence, symmetry as well as decays properties.Comment: revised version, 22 page
A Coordinate-Free Framework for Robotic Pizza Tossing and Catching
This chapter presents a solution to the problem of autonomous pizza tossing and catching. Under the assumption that robotic fingers grasp the pizza dough with soft contact, the grasp constraints are formulated and used to derive the individual and combined Euler-Lagrange dynamic equations of motion of the robotic manipulator and the dough. In particular, the dynamics of the dough is a modified version of the rigid-body dynamics, taking into account the change of inertia due to its deformation. Through these mathematical models, the two control problems of tossing and catching are formulated. For the tossing phase, an exponentially convergent controller that stabilizes a desired velocity of the dough as it leaves the fingers, is derived. On the other hand, to catch the dough, an optimal trajectory for the end-effector of the robotic manipulator is generated. Finally, the control laws to make the optimal trajectory exponentially attractive are derived. The developed theory is demonstrated with an elaborate simulation of the tossing and catching phases. This chapter is based on the work presented in [1]
Experimental evaluation of synergy-based in-hand manipulation
In this paper, the problem of in-hand dexterous manipulation has been addressed on the base
of postural synergies analysis. The computation of the synergies subspace able to represent grasp and
manipulation tasks as trajectories connecting suitable configuration sets is based on the observation of
the human hand behavior. Five subjects are required to reproduce themost natural grasping configuration
belonging to the considered grasping taxonomy and the boundary configurations for those grasps that
admit internal manipulation. The measurements on the human hand and the reconstruction of the human
grasp configurations are obtained using a vision-based mapping method that assume the kinematics
of the robotic hand, used for the experiments, as a simplified model of the human hand. The analysis
to determine the most suitable set of synergies able to reproduce the selected grasps and the relative
allowed internal manipulation has been carried out. The grasping and in-hand manipulation tasks have
been reproduced bymeans of linear interpolation of the boundary configurations in the selected synergies
subspace and the results have been experimentally tested on the UB Hand IV
Comparison of alternate and original forms of the Montreal Cognitive Assessment (MoCA): an Italian normative study
Objective: The Montreal Cognitive Assessment (MoCA) is a screening test widely used in clinical practice and suited for detection of Mild Cognitive Impairment. Alternate forms of the MoCA were developed to avoid \u201clearning effect\u201d in serial assessments, and the present study aimed at investigating inter-form parallelism and at providing normative values for the Italian versions of MoCAs 2 and 3. Method: Three separate convenience samples were recruited: the first (n = 78) completed three alternate MoCA versions for ascertaining inter-form parallelism; the second (n = 302) and the third (n = 413) samples were administered MoCA 2 or 3 to compute normative data. Results: A three-step procedure complemented by confirmatory factor analysis and a mixed factorial ANOVA suggested that the three MoCA versions are not strictly parallel. Multiple linear regression analysis revealed that age and education significantly influenced MoCA 2 and 3 total scores. No significant effect of sex was found. From the derived linear equation, correction grids for MoCA 2 and 3 raw scores were built and equivalent scores computed. Inferential cutoff for adjusted scores, estimated using a non-parametric technique, were 17.49 for MoCA 2 and 18.34 for MoCA 3. Correlation analysis showed strong correlations of MoCA 2 (r = 0.69, p <.001) and MoCA 3 (r = 0.61, p <.001) adjusted total scores with MMSE adjusted scores. Conclusion: The three MoCA forms are not strictly parallel. Specifically developed normative data must be adopted for using MoCA in serial cognitive assessments for clinical and research studies
Methylene blue adsorption on thermo plasma expanded graphite in a multilayer column system
The removal of dyes from wastewater is an important topic in environmental applications. Methylene blue (MB) is one of the most worrisome compounds, as it is widespread and used in many industrial activities. Adsorption represents an effective technique for the removal of this contaminant. Thermo plasma expanded graphite (TPEG) is an industrial material characterized by a fibrous morphology, a very low density and overlapped graphene layers. TPEG has a higher specific surface compared to conventional thermo-expanded graphite and it can establish effective attractive forces with charged pollutants. These properties make TPEG a very promising adsorbent material. In the present work, TPEG was tested in an innovative multilayer column system to treat MB contaminated solutions. Several batch experiments were carried out by varying pH, initial MB concentration and temperature. The optimal adsorption performance was assessed at pH 11, around which the TPEG assumed the maximum negative charge. Based on these results, the adsorption mechanism appeared to be related mainly to electrostatic interactions. At room temperature, the greatest amount of MB adsorbed on TPEG was detected by treating solutions with an initial concentration of 30 mgMB/L. The temperature increase from 20 to 40 °C caused an enhanced adsorption capacity when concentrations higher than 10 mgMB/L were treated. The adsorption trends were accurately described by a pseudo-second order kinetic law and the adsorption isotherms at 20 and 40 °C were found to follow both the features of Freundlich and Langmuir models. The adsorption capacity was estimated to reach threshold values around 95 mgMB/gTPEG and 265 mgMB/gTPEG at 20 and 40°C, respectively. The Gibbs energy change (ΔG°) was calculated to about −7.80 kJ/mol, which proved that the process is spontaneous from a thermodynamic point of view. Finally, it was verified that TPEG can be efficiently reused 5 times after a simple chemical regeneration phase with HCl
A SCIENTOMETRIC REVIEW ON LEUCISM IN WILD DOLPHINS
ABSTRACTLeucism, a category of partial albinism, has been observed in several marine mammals, including cetaceans. The underlying mutations, however, have not yet been identified, and a severe knowledge gap concerning this condition in these animals, has, therefore, been noted. In this context, the present study performed a scientometric-based review on leucism in dolphins, assessing the distribution of confirmed cases worldwide. Reports ranged from 1929 to 2019, with a total of only 14 records on confirmed leucism cases obtained from the literature. This extremely low number of records confirms the significant knowledge gap for leucism in dolphins, hindering further discussions and insightsinto the ecological and physiological implications of this condition. All records report on leucistic dolphin sightings in the northern hemisphere, except for one, in southeastern Brazil. The potential causes of this condition are discussed for the investigated populations, and the role of citizen science is highlighted as a potential tool to obtain further information on the subject.RESUMOO leucismo, uma categoria de albinismo parcial, tem sido observado em vários mamíferos marinhos, incluindo cetáceos. As mutações subjacentes, no entanto, ainda não foram identificadas, e uma grave lacuna de conhecimento sobre essa condição nesses animais foi observada. Neste contexto, o presente estudo realizou uma revisão baseada em cienciometria acerca de leucismo em golfinhos, avaliando a distribuição de casos confirmados ao redor do mundo. Registros variaram de 1929 a 2019, com um total de apenas 14 registros de casos confirmados de leucismo obtidos na literatura. Este número extremamente baixo de registros confirma a significativa lacuna de conhecimento do leucismo em golfinhos, dificultando discussões e percepções adicionais sobre as implicações ecológicas e fisiológicas dessa condição. Todos os registros relatam avistamentos de golfinhos leucísticos no hemisfério norte, exceto um, no sudeste do Brasil. As causas potenciais dessa condição são discutidas para as populações investigadas, e o papel da ciência cidadã é destacado como uma ferramenta potencial para obter mais informações sobre o assunto.Palavras-chave: Albinismo; Coloração anormal; Cetáceo; Análise cienciométrica; Avistamentos de golfinhos
Haptic-Based Shared-Control Methods for a Dual-Arm System
We propose novel haptic guidance methods for a dual-arm telerobotic manipulation system, which are able to deal with several different constraints, such as collisions, joint limits, and singularities. We combine the haptic guidance with shared-control algorithms for autonomous orientation control and collision avoidance meant to further simplify the execution of grasping tasks. The stability of the overall system in various control modalities is presented and analyzed via passivity arguments. In addition, a human subject study is carried out to assess the effectiveness and applicability of the proposed control approaches both in simulated and real scenarios. Results show that the proposed haptic-enabled shared-control methods significantly improve the performance of grasping tasks with respect to the use of classic teleoperation with neither haptic guidance nor shared control
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