Hand-written English numeral recognition system using neural network

This thesis aims at implementing an algorithm for recognition of hand-written English numeral. Handwriting recognition has been one of the active and challenging research areas in the field of image processing and pattern recognition. In this thesis the digits are classified into two groups, one group comprises of blobs with/without stems and the other digits with stems only. The blobs are identified based on a new concept called morphological region filling technique. This eliminates the issue of finding the size of blobs and their structuring elements. This method completely eliminates the complex process of recognition of horizontal or vertical lines. This extracted feature will then classified with the help of neural network train tool. It is a faster English numeral recognition algorithm it uses part of the character instead of complete image

Orientational dynamics and rheology of active suspensions in weakly viscoelastic flows

Microswimmer suspensions are constantly in non-equilibrium and exhibit macroscale properties that are in stark contrast to passive suspensions. Motivated by ubiquitous microbial systems suspended in biological fluids, we analyse the rheological response of a suspension of elongated microswimmers to a steady shear flow in a weakly viscoelastic fluid. At the individual level, we find that the viscoelastic stresses generated by activity substantially modify the Jeffery orbits well-known from Newtonian fluids. The orientational dynamics depends on the swimmer type and, in particular, microswimmers can resist flow-induced rotation and align at an angle with the flow. To analyze its impact on the bulk rheological response, we study a dilute ensemble of microswimmers in the presence of stochastic noise due to tumbling and rotational diffusion. Compared to Newtonian fluids, activity and its elastic response in polymeric fluids alter the orientational distribution and substantially amplify the swimmer-induced viscosity. This suggests that pusher suspensions reach the regime of superfluidity at lower volume fractions.Comment: 18 pages, 9 figure

On the cross-streamline lift of microswimmers in viscoelastic flows

The current work studies the dynamics of a microswimmer in pressure-driven flow of a weakly viscoelastic fluid. Employing a second-order fluid model, we show that a self-propelling swimmer experiences a viscoelastic swimming lift in addition to the well-known passive lift that arises from its resistance to shear flow. Using the reciprocal theorem, we evaluate analytical expressions for the swimming lift experienced by neutral and pusher/puller-type swimmers and show that they depend on the hydrodynamic signature associated with the swimming mechanism. We find that, in comparison to passive particles, the focusing of neutral swimmers towards the centerline can be significantly accelerated, while for force-dipole swimmers no net modification in cross-streamline migration occurs.TU Berlin, Open-Access-Mittel – 202

Self-propulsion in 2D Confinement: Phoretic and Hydrodynamic Interactions

Chemically active Janus particles generate tangential concentration gradients along their surface for self-propulsion. Although this is well studied in unbounded domains, the analysis in biologically relevant environments such as confinements is scarce. In this work, we study the motion of a Janus sphere in weak confinement. The particle is placed at an arbitrary location, with an arbitrary orientation between the two walls. Using the method of reflections, we study the effect of confining planar boundaries on the phoretic and hydrodynamic interactions, and their consequence on the Janus particle dynamics. The dynamical trajectories are analyzed using phase diagrams for different surface coverage of activity and solute-particle interactions. In addition to near wall states such as `sliding' and `hovering', we demonstrate that accounting for two planar boundaries reveals two new states: channel-spanning oscillations and damped oscillations around the centerline, which were characterized as `scattering' or `reflection' by earlier analyses on single-wall interactions. Using phase diagrams, we highlight the differences in inert-facing and active-facing Janus particles. We also compare the dynamics of Janus particles with squirmers for contrasting the chemical interactions with hydrodynamic effects. Insights from the current work suggest that biological and artificial swimmers sense their surroundings through long-ranged interactions, that can be modified by altering the surface properties.Comment: To appear in European Physical Journal

Proton pump inhibitor: a risk factor for spontaneous bacterial peritonitis in Indian cirrhotics decompensated with ascites

Background: Spontaneous bacterial peritonitis (SBP) is common complication of cirrhosis caused by bacterial translocation. Bacterial colonization and overgrowth may occur in GI tract on suppression of gastric acid secretion. Beta-blockers have been postulated to reduce intestinal permeability. There is no significant Indian study to evaluate association of PPI with SBP in cirrhotic ascites. We aimed to assess the effect of PPI in cirrhotic patients decompensated with ascites.Methods: A retrospective case control study (January 2016 to April 2018), evaluated subjects with cirrhosis and ascites. Two study groups of cirrhotic subjects with and without SBP were formed. In each of the two study groups, 143 subjects, were enrolled by matching for age, year of admission, Child-Pugh-Turcotte (CTP) class after considering the inclusion and exclusion criteria. PPI use and various other correlates were compared in both study groups. SPSS ver 24.0 was used for statistical analysis.Results: About 69.23% subjects were using PPI prior to admission in SBP group, which was significant compared to only 31.47% in cirrhotics without SBP (p 0.003). On multivariate analysis PPI use was an independent risk factor for SBP (OR 2.24, 95% CI: 1.01-4.24; p value 0.033) and beta blocker use was protective (OR 0.58; 95% CI: 0.4-0.8; p 0.001).Conclusions: PPI use doubles the risk of development of SBP in cirrhotics decompensated with ascites. In contrast, Beta blockers use significantly lowers the risk of SBP

Pair-Interactions of Self-Propelled SiO2-Pt Janus Colloids

Driven by the necessity to achieve a thorough comprehension of the bottom-up fabrication process of functional materials, this experimental study investigates the pair-wise interactions or collisions between chemically active SiO2-Pt Janus Colloids. These collisions are categorized based on the Janus colloids' orientations before and after they make physical contact. In addition to the hydrodynamic interactions, the Janus colloids are also known to affect each other's chemical field, resulting in chemophoretic interactions, which depend on the reactive nature of the metal site. These interactions lead to a noticeable decrease in particle speed and changes in orientation, which depends on the duration of contact, yielding different collision types. Our findings reveal distinct configurations of contact during collisions, whose mechanisms and likelihood is found to be dependent primarily on the chemical interactions. Such estimates of collision and their characterization in dilute suspensions shall have key impact in determining the arrangement and time scales of dynamical structures and assemblies of denser suspensions, and potentially the functional materials of the future.Comment: 15 pages, 11 figures