High-temperature laser-scanning confocal microscopy as a tool to study the interface instability during unsteady-state solidification of low-carbon steel

Solidification microstructure is a defining link between production techniques and the mechanical properties of metals and in particular steel. Due to the difficulty of conducting solidification studies at high temperature, knowledge of the development of solidification microstructure in steel is scarce. In this study, a laser-scanning confocal microscopy (LSCM) has been used to observe in situ and in real-time the planar to cellular to dendritic transition of the progressing solid/liquid interface in low carbon steel. Because the in situ observations in the laser-scanning confocal microscopy are restricted to the surface, the effect of sample thickness on surface observations was determined. Moreover, the effect of cooling rate and alloy composition on the planar to cellular interface transition was investigated. In the low-alloyed, low-carbon steel studied, the cooling rate does not seem to have an effect on the spacing of the cellular microstructure. However, in the presence of copper and manganese, the cell spacing decreased at higher cooling rates. Higher concentrations of copper in steel resulted on an increased cell spacing at the same cooling rates.

Benzene adsorption at the aqueous (011) α-quartz interface : is surface flexibility important?

Atomistic simulations of molecular adsorption onto inorganic substrates under aqueous conditions can be used to guide the rational design of new materials, fabricated using biomimetic methods. The success of such work depends critically on the model used. Here, we investigate the impact of using a rigid structural model of the (0 1 1) ?-quartz surface, over a fully flexible model, on the calculated free energy change in the adsorption of a single molecule of benzene (a simple analogue of the amino acid phenylalanine) from liquid water. Subtle differences in the mobility of the adsorbate close to the surface result in the free energy of adsorption being overestimated by the rigid model, relative to the fully flexible case. Moreover, we find that the distribution of bound configurations of the adsorbate at their respective free energy minima is different between the two models.

Multipoint haptic mediator interface for robotic teleoperation

Despite recent advances in artificial intelligence and autonomous robotics, teleoperation can provide distinct benefits in applications requiring real-time human judgement and intuition. However, as robotic systems are increasingly becoming sophisticated and are performing more complex tasks, realizing these benefits requires new approaches to teleoperation. This paper introduces a novel haptic mediator interface for teleoperating mobile robotic platforms that have a variety of manipulators and functions. Identical master-slave bilateral teleoperation of the robotic manipulators is achieved by representing them in virtual reality and by allowing the operator to interact with them using a multipoint haptic device. The operator is also able to command motions to the mobile platform by using a novel haptic interaction metaphor rather than a separate dedicated input device. The presented interaction techniques enable the operator to perform a wide range of control functions and achieve functionality similar to that of conventional teleoperation schemes that use a single haptic interface. The mediator interface is presented, and important considerations such as workspace mapping and scaling are discussed. © 2015 IEEE.

Haptics interface for modelling and simulation of flexible cables

Virtual reality systems are becoming a must for product and process design, training practices and ergonomic analysis in many manufacturing industries. The automotive sector is considered to be the leader in applying virtual reality (VR) solutions for real-world, non-trivial, problems. Although, a number of commercial 3D engineering tools for digital mockups exist, most of them lack intuitive direct manipulation of the digital mockups. The majority of these 3D engineering tools are constrained to the interaction mainly with rigid objects which is just half the story. To bridge this gap, we have developed a haptics interface for modelling and simulation of flexible objects. The graphical and haptic user interface developed allows the creation of multiple one dimensional (1D) flexible objects, such as hoses, cables and harnesses. The user is required to provide the mechanical properties of the material such as Young's modulus, Poisson's ratio, material density, damping factors, as well as dimensional properties such as length, and inner and outer diameters of the flexible object. Flexilution solver is employed to estimate and simulate the dynamic behaviour of flexible objects in response to external user interaction, whereas Nvidia's generic physics engine is used to simulate the behaviour of rigid objects. A generic communication interface is developed to accommodate a variety of devices without the reconfiguration of the simulation platform.

Laboratory studies on the coupled oscillations between an internal density interface and a shear layer

The results from experiments conducted in a 2m high flow compartment at large Reynolds numbers are reported in this paper. Flow entered the compartment through an opening at the base on one side of the compartment and exited from an opening at the bottom of the opposite wall of the compartment. A shear layer is formed at the boundary between the incoming flow and the ambient fluid in the compartment. The impingement of the shear layer on the opposite wall of the compartment gives rise to periodic vortex formation and highly organized oscillations in the shear layer. When a density interface is present inside the compartment, resonance conditions were set up when the oscillations of the internal standing waves were “locked in” with the shear layer oscillations. Under resonance conditions, internal standing waves with amplitudes of up to 0.1m were observed. The formation of the internal standing waves is linked to the shear layer oscillations. Resonance conditions result when the shear layer is oscillating close to the natural frequency of the stratified fluid system in the compartment. The results of this investigation are applicable for fresh water storage in floating bottom-opened tanks in the sea, where under resonance conditions, entrainment rates could be significantly increased.

Extending an industrial root controller : implementation and applications of a fast open sensor interface

An overview is given of the design and implementation of a platform for fast external sensor integration in an industrial robot system called ABB S4CPlus. As an application and motivating example, the implementation of force-controlled grinding and deburring within the AUTOFETT-project is discussed. Experiences from industrial usage of the fully developed prototype confirms the appropriateness of the design choices, thus also confirming the fact that control and software need to be tightly integrated. The new sensor can be used for the prototyping and development of a wide variety of new applications