Torque,temperature and hardening precipitation evolution in dissimilar friction stir welds between 6061-T6 and 2014-T6 aluminum alloys

Dissimilar friction stir butt welds between the 2014-T6 and the 6061-T6 Al alloys were performed with various sets of welding parameters including a lateral shift of the tool from the initial separation between the plates to be welded and by placing the alloys, either on the advancing, or on the retreating side of the weld. Torque and temperature measurements during welding as well as macrographies and hardness profiles measurements were performed after welding. It was found that the welding torque, the temperature, the metal flow and the welds’ hardness profile depend on the proportion of each alloy included in the stirred zone. Those results are attributed to the difference between the softening temperatures of both alloys. The 6061 alloy's HAZ is the weak link in all dissimilar welds. The evolution of the hardening precipitation, the hardness and the local yield strength in the 6061 alloy are therefore modeled. The model reasonably well predicts the experimentally measured hardness of both similar and dissimilar welds. It also explains the influence of the alloys placement or tool lateral shift on the welds hardness by their influence on the precipitate radius and volume fraction.     

A survey of Tactile Human–Robot Interactions

Robots come into physical contact with humans in both experimental and operational settings. Many potential factors motivate the detection of human contact, ranging from safe robot operation around humans, to robot behaviors that depend on human guidance. This article presents a review of current research within the field of Tactile Human–Robot Interactions (Tactile HRI), where physical contact from a human is detected by a robot during the execution or development of robot behaviors. Approaches are presented from two viewpoints: the types of physical interactions that occur between the human and robot, and the types of sensors used to detect these interactions. We contribute a structure for the categorization of Tactile HRI research within each viewpoint. Tactile sensing techniques are grouped into three categories, according to what covers the sensors: (i) a hard shell, (ii) a flexible substrate or (iii) no covering. Three categories of physical HRI likewise are identified, consisting of contact that (i) interferes with robot behavior execution, (ii) contributes to behavior execution and (iii) contributes to behavior development. We populate each category with the current literature, and furthermore identify the state-of-the-art within categories and promising areas for future research.     

Therapy for youths with anxiety disorders: A second randomized clincal trial.

Ninety-four children (aged 9-13 years) with anxiety disorders were randomly assigned to cognitive behavioral treatment or waiting-list control. Outcomes were evaluated using diagnostic status, child self-reports, parent and teacher reports, cognitive assessment and behavioral observation; maintenance was examined using l-year follow-up data. Analyses of dependent measures indicated significant improvements over time, with the majority indicating greater gains for those receiving treatment. Treatment gains returned cases to within nondeviant limits (i.e., normative comparisons) and were maintained at l-year follow-up. Client age and comorbid status did not moderate outcomes. A preliminary examination of treatment segments suggested that the enactive exposure (when it follows cognitive-educational training) was an active force in beneficial change. Discussion includes suggestions for future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A dynamical system approach to realtime obstacle avoidance

This paper presents a novel approach to real-time obstacle avoidance based on Dynamical Systems (DS) that ensures impenetrability of multiple convex shaped objects. The proposed method can be applied to perform obstacle avoidance in Cartesian and Joint spaces and using both autonomous and non-autonomous DS-based controllers. Obstacle avoidance proceeds by modulating the original dynamics of the controller. The modulation is parameterizable and allows to determine a safety margin and to increase the robot’s reactiveness in the face of uncertainty in the localization of the obstacle. The method is validated in simulation on different types of DS including locally and globally asymptotically stable DS, autonomous and non-autonomous DS, limit cycles, and unstable DS. Further, we verify it in several robot experiments on the 7 degrees of freedom Barrett WAM arm.     

The activity of the Synechocystis PCC6803 AbrB2 regulator of hydrogen production can be post-translationally controlled through glutathionylation

We show that the Synechocystis AbrB2 repressor of hydrogen production, down regulates the defence against oxidative stress. The single widely conserved cysteine of AbrB2 is also shown to play a crucial role in AbrB2 oligomerisation, and in AbrB2-mediated repression of the hydrogenase encoding operon (hoxEFUYH) and a wealth of other genes. Very interestingly, our results indicate that this cysteine is the target of glutathionylation, which affects the binding of AbrB2 on the hox operon-promoter DNA, as well as the stability of AbrB2 at the non-standard temperature of 39 °C. Similarly, we show that the cysteine of the other hoxEFUYH regulator AbrB1 can also be glutathionylated in vitro. These novel findings will certainly stimulate the in depth analysis of the influence of glutathionylation on the production of hydrogen, a field totally overlooked so far. They also emphasize on the evolutionary conservation of glutathionylation, a process mostly described in eukaryotes, so far.     

Integrated microfluidic-microoptical systems fabricated by dry etching of soda-lime glass

In the paper, the method of fabrication of monolithically integrated microfluidic-microoptics systems is presented. Soda-lime glass is used as a substrate material, in which the waveguiding optics is fabricated by means of an ion exchange process, whereas the microfluidic channel is manufactured using reactive ion etching technique. Basic optical characteristics of the device are also reported.     

Robota: Clever toy and educational tool

Therapeutic and educational applications of robots have created a demand for robots showing a number of social skills. These skills include the capacity to imitate, to learn from demonstration, to interpret gestures and to recognize speech. Robot toys are an ideal platform to investigate the potential and limitations of human–robot social interactions.

This paper presents Robota, a mini-humanoid doll-shaped robot. Robota is used in an introductory robotics class at the undergraduate level. The class offers an introduction to different tools necessary for building human–robot social interactions. Through a series of hands-on projects, students learn how to use vision and speech processing and how to design learning algorithms. The goal of each project is to create an educational and entertaining game for normal and disabled children.     

Alternating TLM symmetrical condensed node

A new alternating scheme for the transmission line matrix (TLM) method is proposed. As shown, this scheme is no longer based on the alternate use of TLM cells in the computational volume, but rather on an alternating process in the cell itself. This feature allows easy treatment of boundaries, which is the usual drawback of alternating schemes