Rendering Strategy to Counter Mutual Masking Effect in Multiple Tactile Feedback

Recently, methods and devices that simultaneously utilize two or more tactile feedback types have been proposed for more immersive interaction with virtual objects. However, the masking effect, which makes us less sensitive to various stimuli presented at the same time, has scarcely been explored. In this study, we propose a novel tactile rendering algorithm that can eliminate the mutual masking effect at the user’s sensation level, when mechanical vibration and electrovibration are applied simultaneously. First, the masking functions of the two stimuli were investigated for various stimulus combinations. Based on these, a generalized form of the masking function was derived. We then tested and confirmed that the proposed algorithm, which calculates the required stimulus intensity to compensate for the mutual masking effect, could render the arbitrary stimulus intensity desired to be perceived by the users. The results of the user test revealed that the proposed rendering algorithm significantly improved the virtual object recognition rate by approximately 23% when geometry and texture were presented jointly. This finding suggests principal guidelines for the combined use of mechanical vibration and electrovibration, as well as for other combinations of different tactile feedback types.

Correctness problem of the threshold method of modular sharing of secrets with masking transformation

The article formulates the principles of constructing threshold cryptographic schemes for secret sharing based on a modular coding and a linear masking function with an additive variational component of pseudo-random type. The main attention is paid to the correctness problem of schemes of the considered class within the limits of the accepted model. The congruent condition in the module of the secret-original ring of the masking function values in full and partial modular number systems is obtained. On the basis of the above-said, the method of correct implementation of the threshold principle of secret information sharing is developed. The proposed approach to solving the problem under study is demonstrated by specific numerical examples.

Experimental Study on Corrosion Prevention of a Multilayer Coating System

Aiming to the corrosion prevention of 16MnR steel surface in the light aggregate concrete, the paper applies a kind of corrosion prevention system composed of layered coating. It utilizes measurement methods such as field emission scanning electron microscopy and energy disperse spectroscopy to study the corrosion and change process of this kind of coating system in the surface of 16MnR steel in the environment of light aggregate concrete and make the evaluation on its effect of corrosion protection. The experiment result indicates that due to its mechanical masking function, the layered coating system can effectively restrain immersion of the corrosive medium in early corrosion period so as to protect the metallic matrix. With the deepening of the corrosion, the nanometer Zn particle has the function of cathodic protection on the metallic matrix, effectively enhancing the comprehensive corrosion protection ability of the coating system.

Application of an Immersed Boundary Method to Flow in Cerebral Aneurysms and Porous Media

We present the development and application of an immersed boundary (IB) method for the simulation of incompressible flow inside and around complex geometrical shapes and cavities. The IB method is based on a volume-penalization method that is applied throughout the domain, rendering the velocity in stationary solid parts negligibly small, while the flow in the open parts of the domain is governed by the Navier-Stokes equations. The flow solver is based on a skew-symmetric finite-volume discretization in combination with explicit time-stepping for the convective and viscous fluxes, and implicit time-stepping for the IB forcing term. The complex domain is characterized in terms of a so-called ‘masking function’ which equals unity in the solid parts and zero in the open parts of the domain. The focus is on the accuracy with which gradients of the solution close to solid walls can be approximated using the IB methodology. We investigate this for flow through a model of an aneurysm as may develop in the circle of Willis in a human brain, and to flow in a structured porous medium composed of a regular spatial arrangement of square rods. The shear stress acting on the vessel walls in case of flow through an aneurysm, and the permeability of the porous material, are analyzed. The computational method converges as a first order method for Poiseuille flow, with a considerable influence derived from the precise definition of the masking function near solid-fluid interfaces. We identify the best masking function strategy and show that for plane Poiseuille flow even second order convergence may be obtained. Qualitatively reliable results are obtained already at modest resolutions of 8–16 grid cells across a characteristic opening in the flow domain, e.g., the vessel diameter or the size of the gap between individual square rods.