A necessary and sufficient condition for the perspective observability problem

In this paper we derive a necessary and sufficient condition for observing the initial condition of a new class of system known as the perspective system. Such a system has already been applied in the field of computer vision especially in the area of motion estimation problems. Our result generalizes an earlier result by Popov-Belevitch-Hautus on the problem of observing a linear dynamical system.     

Minimum energy optimal external torque control of human binocular vision

In this paper, we consider eyes from the human binocular system, that simultaneously gaze on stationary point targets in space, while optimally skipping from one target to the next, by rotating their individual gaze directions. The head is assumed fixed on the torso and the rotating gaze directions of the two eyes are assumed restricted to pass through a point in the visual space. It is further assumed that, individually the rotations of the two eyes satisfy the well known Listing’s law. We formulate and study a combined optimal gaze rotation for the two eyes, by constructing a single Riemannian metric, on the associated parameter space. The goal is to optimally rotate so that the convergent gaze changes between two pre-specified target points in a finite time interval [0, 1]. The cost function we choose is the total energy, measured by the L2 norm, of the six external torques on the binocular system. The torque functions are synthesized by solving an associated ‘two-point boundary value problem’. The paper demonstrates, via simulation, the shape of the optimal gaze trajectory of the focused point of the binocular system. The Euclidean distance between the initial and the final point is compared to the arc-length of the optimal trajectory. The consumed energy, is computed for different eye movement chores and discussed in the paper. Via simulation we observe that certain eye movement maneuvers are energy efficient and demonstrate that the optimal external torque is a linear function in time. We also explore and conclude that splitting an arbitrary optimal eye movement into optimal vergence and version components is not energy efficient although this is how the human oculomotor control seems to operate. Optimal gaze trajectories and optimal external torque functions reported in this paper is new.     

Transient MHD convective flow of a micropolar fluid past a moving vertical plate in the presence of thermal diffusion

In this article, we investigate a transient magnetohydrodynamic convective micropolar fluid flow over a semi-infinite vertical plate embedded in a porous medium in the presence of chemical reaction and thermal diffusion. The dimensionless governing equations are solved by adopting the regular perturbation technique. The impact of various parameters on the velocity, microrotation, temperature, concentration profiles, skin friction, Sherwood number, and Nusselt number over the boundary layer is analyzed using graphs. The fluid velocity and microrotation reduce under the effect of thermal diffusion and chemical reaction. Furthermore, concentration rises due to thermal diffusion (Soret) effect, but concentration falls under the effect of chemical reaction. It is found that the velocity and skin friction fall with enhancing value of magnetic parameter. But Sherwood number increases as the magnetic parameter increase.     

Analysis of time-dependent dynamics of micropolar fluid subject to Lorentz force,energy flux due to a concentration gradient and viscous dissipation

This study deals with an analysis of the time-dependent dynamics of micropolar fluid flow subject to Lorentz force, diffusion thermal, and viscous dissipation effect past a uniformly moving semi-infinite porous plate in the presence of chemical reaction. Expressions of velocity, microrotation, concentration, temperature, skin friction, Sherwood number, and Nusselt number are established and the effect of several parameters on them are represented graphically. Equations governing the flow and heat transfer are solved by adopting the regular perturbation technique. It is noticed that temperature distribution as well as the coefficient of friction is enhanced due to the diffusion thermo effect. It is observed that the microrotation increases with increasing magnetic parameters. Furthermore, the study confirms a drop in fluid concentration under the composition of species.     

Recent Approaches to Antifungal Therapy for Invasive Mycoses

Antimycotic agents : Diverse classes of antimycotic drugs have been developed over the past decades with the goal of improving selectivity and efficacy. This review discusses both conventional and novel targets for antifungal agents and the possibility of vaccination in the treatment of invasive fungal infections.

     

The occurrence of vulnerable seagrass species Halophila beccarii Ascherson, 1871 from restored mangrove of Koduvally Estuary,south‐west coast of India

The ocean turf grass, Halophila beccarii Ascherson, 1871 was recorded for the first time in the intertidal region of the restored mangrove ecosystem of the Koduvally Estuary on the south‐west coast of India. It was found co‐existing in the shallow muddy area of the mangroves, dominated by mangrove trees of Rhizophora mucronata and Sonneratia alba, and macroalgae, Ulva sp., Enteromorpha sp. and Chaetomorpha sp. The meadow is sparsely scattered with shoots near the mangroves, with a mean density of 720 shoots/m². Details regarding the morphology and hydrographic conditions are described. The occurrence of H. beccarii in the Koduvally estuary is an encouraging sign of improved ecosystem health through mangrove restoration. The development of seagrass meadow in the estuary will improve the sediment stability and water quality. A further comprehensive study on the spatiotemporal variation of this species in the estuary is also recommended for conservation and management of this vulnerable seagrass species.     

Redundant binary partial product generators for compact accumulation in Booth multipliers

The use of signed-digit number systems in arithmetic circuits has the advantage of constant time addition. When signed-digit number systems are used in binary, they are referred as redundant binary. Here, we present a new encoding technique for generating redundant binary partial products for a multiplier, without using any additional hardware. We express each normal binary partial product in one's complement form, with an extra bit denoting the sign bit. The proposed redundant binary partial product generator (RBPPG) achieves the highest reduction in the number of partial products (75%) for a radix-4 multiplier. The carry-free nature of redundant binary adders is exploited to add the extra bits with the partial products, without using any extra adder stages. The new partial product generation (PPG) technique is shown to improve the speed of multipliers, with the least number of adder stages, irrespective of the multiplier size.     

Effect of nanorough surface in evaluating the handle of nanofiber web

The effect of frictional coefficient on handle measurement of the nanofiber webs was studied by using a home-made apparatus. The instrument measures directly the frictional coefficient between the finger and the nanofiber web. The stick-slip phenomenon was observed in friction of polyurethane (PU) nanofiber webs and nylon nanofiber laminate-coated nylon 6 fabrics above the critical load of approximately 1 N. Conventional friction test was also carried out on Kawabata Evaluation System (KES FB 4) which did not show stick-slip process up to a load of 0.49 N. Moreover, it was found that the frictional coefficient of PU nanofiber webs and nylon nanofiber laminate-coated nylon 6 fabrics decreased despite the increase in applied load, indicating that Coulomb-Amonton's friction law did not hold good. However, conventional nylon fabric was found to exhibit friction behaviour independent of the applied load. Possible reason attributed to these phenomena is discussed in terms of the repeated adhesion-shear deformation behavior between the nanofiber web and the forefinger.     

An Investigation on Turning Hardened Steel Using Different Tool Inserts

Turning of hard materials usually presents poor machinability. However, for high productivity, it is desirable to employ turning of hard materials rather than grinding. In this work, turning of hardened 16MnCrS5 steel with hardness of 43 HRC was explored to judge machining performance with plain and wide-groove-type chip-breaking TiC-coated carbide inserts under dry and wet environmental conditions, different cutting velocity, and feed. Tool wear tests were also done in dry and wet conditions. Satisfactory tool performance was observed under wet condition using TiC-coated plain and wide-groove carbide inserts even at 268 m/min cutting velocity, when dry machining could not be done effectively.