1,721,039 research outputs found
Density measurements on C12Ej nonionic micellar solutions as a function of the head group degree of polymerization (j from 5 to 8)"
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Non è un Paese per l'evidenza... e pur si muove. Peculiarità, limiti e potenzialità delle sperimentazioni controllate nel sistema scolastico italiano
No full textSi illustrano peculiarità e limiti delle sperimentazioni controllate nel sistema educativo italiano
Interactions at the CMC/magnetite interface:Implications for the stability of aqueous dispersions and the magnetic properties of magnetite nanoparticles
No full textMagnetite NPs modified with CMC, a polysaccharide containing carboxylic groups derived from cellulose, were prepared. Two different methods were used: addition of CMC to a dispersion of magnetite NPs previously synthesized (ex situ preparation) and addition of NaOH to an aqueous solution of Fe(II) and Fe(III) in the presence of CMC (in situ preparation). The aim of this study was to characterize in detail the interactions between magnetite NPs and CMC and to elucidate the effect of the polymer on the magnetite NP agglomeration. FTIR spectroscopy was used to shed light onto the nature of the interactions between CMC and Fe3O4 NPs. The morphological characterization of the NPs was carried out by FESEM. The size and the ζ-potential of the NPs in various aqueous media were determined by DLS. XRD measurements indicate that the presence of CMC does not modify, within the uncertainty of the measurement, the size of the primary particle (ca. 10 nm). FTIR spectra suggest that CMC chains are anchored to magnetite NPs via carboxylate groups interacting with iron ions at the surface. The FESEM images show that magnetite NPs prepared by the in situ method form aggregates which are significantly smaller than those prepared by the ex situ procedure. The FESEM images reveal a different morphology of the polymeric matrix between the CMC/magnetite NPs prepared following the two procedures. The hydrodynamic diameter of the CMC/magnetite NPs in water at neutral pH prepared in the presence of CMC is 280 nm. The ζ-potential (ca. −80 mV) measured for the dispersions in water at neutral pH of CMC/magnetite NPs prepared according to the two methods explains their long-term stability. The magnetic behaviour of the CMC/magnetite NPs can be explained considering the different size of the aggregates in the two kinds of sample
Self-Modulated Adaptive Robotic Deposition: an Application to the Aerospace Industry
No full textIn modern industrial applications, the ability of robots to learn and adapt their motion is increasingly necessary. This is particularly true in tasks such as welding and material deposition, where the robot must plan and execute a path for a wide range of target scenarios. The current method of setting up these applications requires expert operators to manually generate a robot path for each part, which is a time-consuming process that can take at least one day to complete for each new part. In the case of deposition tasks, several activities must be carried out, including generating a deposition path in the CAD environment, converting the path into robot instructions, defining collisions-free robot motion, testing for quality assessment, and updating the path for desired deposition quality. To reduce setup time and standardize the task, there is a high demand for automating the path generation to achieve the desired quality. This paper focuses on automatic sealant deposition for the assembly of aerospace parts, which requires adapting the deposition path based on the target part geometry and material properties. The proposed Self-Modulated Adaptive Robotic Deposition (SMART DEPOSITION) tool offers a solution for generating and adapting robot motion in response to the deposition requirements of a target part. To accomplish this, the approach first analyzes the input part geometry to generate a grid of points. Then, an optimal deposition path is computed by exploiting the traveling salesman problem, using multiple approaches such as the nearest neighbor, a two-opt algorithm, and simulated annealing. The generated path can then be used to plan and execute the robot motion, resulting in the desired deposition quality with a standardized approach. The simulation results demonstrate the effectiveness of the proposed approach in optimizing the deposition path for different parts with varying geometries
PROPHET: PReference-Based OPtimization for Human-cEnTric Visual Inspection
No full textNowadays, complex inspection processes rely heavily on human operators, while automatic systems handle simpler tasks. However, these tasks are highly repetitive and demand consistent high-quality performance throughout, leading to significant stress for human workers. In contrast, automatic systems can help alleviate this burden. Nevertheless, configuring automatic inspection systems is challenging due to numerous parameters that require extensive time and trial-and-error adjustments. To address these issues, this project aims to introduce an optimization approach based on user preferences for configuring visual inspection systems. Preference-based optimization is a potent method for enhancing system performance in an intuitive manner. This methodology enables the resolution of optimization problems when the decision-maker cannot directly assess the objective function tied to the problem at hand. Instead, they can only express preferences, such as “this option is better than that" when comparing different decision choices
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Human Preferences' Optimization in pHRI Collaborative Tasks
No full textHumans and robots working together have mutual benefits. The first is great at adaptation to new situations and has very high intellectual capabilities, while robots are very effective in assisting humans with heavy/repetitive tasks. In physical Human-Robot Interaction (pHRI), one challenge is to tune the robot's controller to make the interaction with the human as comfortable and natural as possible. Indeed, robots' perception is different from human to human. Moreover, depending on the target task, different robot tuning may be preferred. In this work, an assistive Game-Theoretic based controller is presented, and its parameters are tuned according to different subjects' preferences. Preference Based Optimization (PBO) allows optimization based on human preferences and feelings. The aim of this study is twofold: present a methodology for fast tuning of a pHRI controller according to the subjective preferences in different situations, and study general human preferences according to two different tasks. The two tasks investigated are a precise path-following task and a fast-reaching task. Experimental evaluations are conducted, and subjective and objective performances are evaluated and discussed. Finally, a questionnaire is proposed to the subjects to evaluate the applicability of the proposed method
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