Wear of Polished Steel Surfaces in Dry Friction Linear Contact on Polimer Composites with Glass Fibres

It is generally known that the friction and wear between polymers and polished steel surfaces has a special character, the behaviour to friction and wear of a certain polymer might not be valid for a different polymer, moreover in dry friction conditions. In this paper, we study the reaction to wear of certain polymers with short glass fibres on different steel surfaces, considering the linear friction contact, observing the friction influence over the metallic surfaces wear. The paper includes also its analysis over the steel’s wear from different points of view: the reinforcement content influence and tribological parameters (load, contact pressure, sliding speed, contact temperature, etc.). Thus, we present our findings related to the fact that the abrasive component of the friction force is more significant than the adhesive component, which generally is specific to the polymers’ friction. Our detections also state that, in the case of the polyamide with 30% glass fibres, the steel surface linear wear rate order are of 10-4 mm/h, respectively the order of volumetric wear rate is of 10-6 cm3 /h. The resulting volumetric wear coefficients are of the order (10-11 – 10-12) cm3/cm and respectively linear wear coefficients of 10-9 mm/cm

3-D Tracking and Visualization of Hundreds of Pt-Co Fuel Cell Nanocatalysts During Electrochemical Aging

We present an electron tomography method that allows for the identification of hundreds of electrocatalyst nanoparticles with one-to-one correspondence before and after electrochemical aging. This method allows us to track, in three-dimensions (3-D), the trajectories and morphologies of each Pt-Co nanocatalyst on a fuel cell carbon support. The use of atomic-scale electron energy loss spectroscopic imaging enables the correlation of performance degradation of the catalyst with changes in particle/inter-particle morphologies, particle-support interactions and the near-surface chemical composition. We found that, aging of the catalysts under normal fuel cell operating conditions (potential scans from +0.6 V to +1.0 V for 30,000 cycles) gives rise to coarsening of the nanoparticles, mainly through coalescence, which in turn leads to the loss of performance. The observed coalescence events were found to be the result of nanoparticle migration on the carbon support during potential cycling. This method provides detailed insights into how nanocatalyst degradation occurs in proton exchange membrane fuel cells (PEMFCs), and suggests that minimization of particle movement can potentially slow down the coarsening of the particles, and the corresponding performance degradation.Comment: Nano Letters, accepte

Pt-Decorated PdCo@Pd/C Core-Shell Nanoparticles with Enhanced Stability and Electrocatalytic Activity for Oxygen Reduction Reaction

A simple method for the preparation of PdCo@Pd core-shell nanoparticles supported on carbon has been developed using an adsorbate-induced surface segregation effect. The stability and electrocatalytic activity for the oxygen reduction of PdCo@Pd nanoparticles was enhanced by a small amount of Pt, deposited via a spontaneous displacement reaction. The facile method described herein is suitable for large-scale lower cost production and significantly lowers the Pt loading and thus cost. The as-prepared PdCo@Pd and Pd-decorated PdCo@Pd nanocatalysts have higher methanol-tolerance for the ORR when compared to Pt/C, and are promising cathode catalysts for fuel cell applications.Comment: 12 pages, 10 figures, accepted by JAC

Task-Specific Sensor Planning for Robotic Assembly Tasks

When performing multi-robot tasks, sensory feedback is crucial in reducing uncertainty for correct execution. Yet the utilization of sensors should be planned as an integral part of the task planning, taken into account several factors such as the tolerance of different inferred properties of the scene and interaction with different agents. In this paper we handle this complex problem in a principled, yet efficient way. We use surrogate predictors based on open-loop simulation to estimate and bound the probability of success for specific tasks. We reason about such task-specific uncertainty approximants and their effectiveness. We show how they can be incorporated into a multi-robot planner, and demonstrate results with a team of robots performing assembly tasks

Autonomous Soft Robotic Fish Capable of Escape Maneuvers Using Fluidic Elastomer Actuators

In this work we describe an autonomous soft-bodied robot that is both self-contained and capable of rapid, continuum-body motion. We detail the design, modeling, fabrication, and control of the soft fish, focusing on enabling the robot to perform rapid escape responses. The robot employs a compliant body with embedded actuators emulating the slender anatomical form of a fish. In addition, the robot has a novel fluidic actuation system that drives body motion and has all the subsystems of a traditional robot onboard: power, actuation, processing, and control. At the core of the fish's soft body is an array of fluidic elastomer actuators. We design the fish to emulate escape responses in addition to forward swimming because such maneuvers require rapid body accelerations and continuum-body motion. These maneuvers showcase the performance capabilities of this self-contained robot. The kinematics and controllability of the robot during simulated escape response maneuvers are analyzed and compared with studies on biological fish. We show that during escape responses, the soft-bodied robot has similar input–output relationships to those observed in biological fish. The major implication of this work is that we show soft robots can be both self-contained and capable of rapid body motion.National Science Foundation (U.S.) (NSF IIS1226883)National Science Foundation (U.S.) (NSF CCF1138967)National Science Foundation (U.S.) (1122374

Ingestible, controllable, and degradable origami robot for patching stomach wounds

© 2016 IEEE.Developing miniature robots that can carry out versatile clinical procedures inside the body under the remote instructions of medical professionals has been a long time challenge. In this paper, we present origami-based robots that can be ingested into the stomach, locomote to a desired location, patch a wound, remove a foreign body, deliver drugs, and biodegrade. We designed and fabricated composite material sheets for a biocompatible and biodegradable robot that can be encapsulated in ice for delivery through the esophagus, embed a drug layer that is passively released to a wounded area, and be remotely controlled to carry out underwater maneuvers specific to the tasks using magnetic fields. The performances of the robots are demonstrated in a simulated physical environment consisting of an esophagus and stomach with properties similar to the biological organs

Self-folding with shape memory composites

Origami-inspired manufacturing can produce complex structures and machines by folding two-dimensional composites into three-dimensional structures. This fabrication technique is potentially less expensive, faster, and easier to transport than more traditional machining methods, including 3-D printing. Self-folding enhances this method by minimizing the manual labor involved in folding, allowing for complex geometries and enabling remote or automated assembly. This paper demonstrates a novel method of self-folding hinges using shape memory polymers (SMPs), paper, and resistive circuits to achieve localized and individually addressable folding at low cost. A model for the torque exerted by these composites was developed and validated against experimental data, in order to determine design rules for selecting materials and designing hinges. Torque was shown to increase with SMP thickness, resistive circuit width, and supplied electrical current. This technique was shown to be capable of complex geometries, as well as locking assemblies with sequential folds. Its functionality and low cost make it an ideal basis for a new type of printable manufacturing based on two-dimensional fabrication techniques.National Science Foundation (U.S.) (award number CCF-1138967)National Science Foundation (U.S.) (award number EFRI-1240383

"Of Mice and Measures": A Project to Improve How We Advance Duchenne Muscular Dystrophy Therapies to the Clinic

A new line of dystrophic mdx mice on the DBA/2J (D2) background has emerged as a candidate to study the efficacy of therapeutic approaches for Duchenne muscular dystrophy (DMD). These mice harbor genetic polymorphisms that appear to increase the severity of the dystropathology, with disease modifiers that also occur in DMD patients, making them attractive for efficacy studies and drug development. This workshop aimed at collecting and consolidating available data on the pathological features and the natural history of these new D2/mdx mice, for comparison with classic mdx mice and controls, and to identify gaps in information and their potential value. The overall aim is to establish guidance on how to best use the D2/mdx mouse model in preclinical studies