Transformation Design Principles as Enablers for Designing Reconfigurable Robots

The design of cleaning and maintenance (CaM) robots are generally limited by their fixed morphologies. Contrary to the fixed robotic systems, design for reconfiguration in robots presents unique challenges. Reconfigurable robots pose the challenge of designing their subsystems and functionalities such that a robot meets its system, performance, and other fixed requirements, while providing reconfiguration capabilities to increase functionality and to provide innovative operational scenarios. Established transformation or reconfiguration principles, namely, expand/collapse, expose/cover, and fuse/divide, observed in several products-services-systems, can be adopted to design subsystems and system for reconfiguration in robots. Essentially these principles in many robots may be governed and implemented. The heuristic approach to design the reconfigurable robotic systems using three layers namely input, formulation and output layer is proposed. This paper used the design principles and associated facilitators and abstracts them to build a reconfigurable pavement cleaning robot named Panthera. Moreover, need, challenges, and design strategies for system and subsystem levels are presented. The system-level reconfiguration is to expand/collapse, whereas the subsystems, namely, i) Varying footprint, ii) Transmission, iii) Storage bin, iv) Cleaning brushes, v) Vacuum/Suction and blowing, and vi) Outer skin or cover are explained. The step-by-step illustration for reconfiguring the system and subsystem of Panthera is done by referring to the transformation principles, precedence, and mechanism adopted to achieve reconfiguration requirements.

THE EFFECTS OF HALL CURRENT ON THE FLOW DUE TO THE OSCILLATING ROTATING POROUS DISK WITH A VISCOUS FLUID AT INFINITY: GRAPHICAL SOLUTIONS USING MATLAB

The flow due to the oscillating rotating porous disk with a viscous fluid at infinity is studied under the influence of Hall current. Governing equations are implied with reasonable approximations and solved analytically to get the expressions for the velocity fields in closed form. Graphical results are presented for the velocity components for various values of parameters namely, the Hall, suction and blowing through MATLAB and a discussion is provided. It is important to note that presented results are valid for all values of the frequencies.

Numerical and experimental investigation of the flow separation over NREL's S822 aerofoil and its control by suction and blowing

In this study, a numerical and experimental investigation for the flow separation over 170 mm chord, the NREL S822 aerofoil low Reynolds number wind turbine blade aerofoil section has been investigated at 15.8 m/s wind speed using suction and blowing techniques for the locations between 0.15 and 0.41 of the chord to improve aerodynamic characteristics of a wind turbine rotor blade. In a numerical study, two-dimensional aerofoil (i.e. NREL S822), using Shear Stress Transport (SST (γ − Reθ)) turbulence model, is presented. Careful selection for the number of mesh was considered through an iterative process to achieve the optimum mesh number resulted in optimum values for the ratio of lift to drag coefficients (CL/CD). Values of the lift coefficient, drag coefficient, and separation location were investigated at an angle of attack 18°. Flow separation is monitored and predicted within the numerical results at the tested angles, which has been compared with the experimental results and should a fair agreement. The results revealed that the aerodynamic characteristics of NERL S822 aerofoil would be improved using the suction technique more than the suction and blowing techniques and there is a delay of flow separation with the increase of blowing or suction volumetric flow rate. Using these two techniques and careful selection of the mesh numbers with the right angle of attack can improve the aerofoil characteristics and therefore lead to improve the turbine performance characteristics.

Reducing visible aerosol generation during phacoemulsification in the era of Covid-19

Objective: To assess potential methods of reducing visible aerosol generation during clear corneal phacoemulsification surgery in the era of Covid-19. Methods: Aerosol generation during phacoemulsification was assessed using a model comprising a human cadaveric corneoscleral rim mounted on an artificial anterior chamber. Typical phacoemulsification settings were used and visible aerosol production was recorded using high speed 4K camera. Aerosolisation was evaluated under various experimental settings: Two different phacoemulsification tip sizes (2.2mm, 2.75mm), varying levels of corneal moisture, the use of suction and blowing air in the surgical field, the use of hydroxypropyl methylcellulose (HPMC) coating of the cornea with a static and moving tip. Results: This model demonstrates visible aerosol generation during phacoemulsification with a 2.75mm phacoemulsification tip. No visible aerosol was noted with a 2.2mm tip. The presence of visible aerosol is unrelated to corneal wetting. Suction in close proximity to the aerosol plume did not impact on its dispersion. Blowing air redirected the aerosol plume towards the ocular surface. Visible aerosol production was abolished when HPMC was used to coat the cornea. This effect lasted for an average of 67±8 seconds in the static model. Visible aerosol generation was discerned during movement of the 2.2mm tip towards the corneal wound. Conclusions: We demonstrate visible aerosol production in the setting of a model of a clear cornea phacoemulsification. Visible aerosol can be reduced using a 2.2mm phacoemulsification tip and reapplying HPMC every minute during phacoemulsification.

Reducing Aerodynamic Noise in a Rod-Airfoil Using Suction and Blowing Control Method

This paper aims at investigating a two-dimensional flow over the rod-airfoil as a simple component of an aircraft using URANS equations. The prediction of the flow-induced noise is performed using F-WH analogy. Since Vortex’s periodic production is the main cause of the noise mechanism, by reducing its effect on the airfoil leading edge, the acoustic propagation reduces as well. To control flow and reduce noise, in this study, the suction and blowing active control method is employed (blowing in the rod, and simultaneous suction and blowing in the airfoil). The range of changes in the intensity (I) of the suction and blowing is (0.1U–0.5U), where [Formula: see text] is the rate of free streamflow. The acoustic study showed that the noise is decreased at [Formula: see text] and [Formula: see text] by 55% and 70%, which is due to the suppression and alleviation of vortices. In addition, by using blowing and suction, the lift force is increased and the drag force is decreased, which is aerodynamically favorable. Strouhal number estimation showed that this parameter was reduced by this control method.