Theoretical analysis of SWCNT- MWCNT/H2O hybrid flow over an upward/downward moving rotating disk

The flow-through various disk movement has wide range of applications in manufacturing processes like, computer storage equipment’s, rotating machines, electronic and various types of medical equipment’s. Inspired from these applications, here we scrutinised the consequences of homogeneous-heterogeneous reactions and uniform heat source/sink on the three-dimensional (3D) hybrid SWCNT-MWCNT’s flow on time dependent moving upward/downward rotating disk. The renowned innovation of this paper is the application of the hybrid nanofluid made up of SWCNT and MWCNT’s. Heat generation/absorption effect for the disk that does not move up or down creates a dual flow on the disk. Alternatively, the rotation and upright motion of the disk creates a 3D flow on the surface which has not been considered in the open literature. The modelled PDE’s are reduced in to ODE’s by opting suitable similarity variables and boundary constraints. Here, we used RKF-45 method to obtain the numerical approximations by adopting shooting technique. The analysis of rate of heat transfer is done through graphs. Further, change in velocity, thermal and concentration profiles for various non-dimensional parameters are deliberated briefly and illustrated with the help of suitable plots. The results reveal that, the, rise in values of homogeneous and heterogeneous reaction parameters improve the rate of reaction which results in reduction of the distribution rate and diminishes the concentration gradient. An increase in expansion/contraction parameter enhances the velocity and thermal gradients.

Low Reynolds Number Flow in Spiral Microchannels

We study the creeping flow of an incompressible fluid in spiral microchannels such as that used in DNA identifying “lab-on-a-chip” installations. The equations of motion for incompressible, time-independent flow are developed in a three-dimensional orthogonal curvilinear spiral coordinate system where two of the dimensions are orthogonal spirals. The small size of the channels results in a low Reynolds number flow in the system, which reduces the Navier–Stokes set of equations to the Stokes equations for creeping flow. We obtain analytical solutions of the Stokes equations that calculate velocity profiles and pressure drop in several practical configurations of channels. Both pressure and velocity have exponential dependence on the expansion/contraction parameter and on the streamwise position along the channel. In both expanding and converging channels, the pressure drop is increased when the expansion/contraction parameter k and/or the curvature is increased.

Postcontraction insulin sensitivity: relationship with contraction protocol, glycogen concentration, and 5′ AMP-activated protein kinase phosphorylation

Exercise enhances insulin-stimulated glucose transport (GT) in skeletal muscle. Evidence suggests that 5′ AMP-activated protein kinase (AMPK) and glycogen may be important for enhanced insulin sensitivity. Our goals were to investigate the effect of various in situ muscle contraction protocols on insulin-stimulated GT and assess the relationship of contraction-induced changes in AMPK and glycogen with postcontraction improvement in insulin-stimulated GT. Rats were anesthetized, both ulnar nerves were exposed, and one nerve was electrically stimulated to contract forelimb muscles. We performed a series of five experiments, sequentially varying only one contraction parameter (train duration, train rate, pulse frequency, number of 5-min bouts, or pulse duration) while holding the others constant. Both epitrochlearis muscles were dissected out and incubated for 3.5 h before measurement of GT. For each contraction parameter studied, we identified an apparent threshold value that did not induce a significant increase in insulin-stimulated GT and an apparent peak value, above which there was a plateau or decline in insulin-stimulated GT. Using other rats, we evaluated muscle AMPK phosphorylation and glycogen concentration immediately postcontraction. AMPK phosphorylation and reduction in glycogen were increased compared with resting controls in each protocol, which had previously been shown to increase insulin-stimulated GT, as well as in several protocols that did not significantly increase insulin-stimulated GT. These data suggest that contraction-induced AMPK phosphorylation and decrease in glycogen may be necessary but are not sufficient for the postcontraction increase in insulin-stimulated GT in rat skeletal muscle.

Recurrent Neural Networks with Small Weights Implement Definite Memory Machines

Recent experimental studies indicate that recurrent neural networks initialized with “small” weights are inherently biased toward definite memory machines (Tiňno, Čerňanský, & Beňušková, 2002a, 2002b). This article establishes a theoretical counterpart: transition function of recurrent network with small weights and squashing activation function is a contraction. We prove that recurrent networks with contractive transition function can be approximated arbitrarily well on input sequences of unbounded length by a definite memory machine. Conversely, every definite memory machine can be simulated by a recurrent network with contractive transition function. Hence, initialization with small weights induces an architectural bias into learning with recurrent neural networks. This bias might have benefits from the point of view of statistical learning theory: it emphasizes one possible region of the weight space where generalization ability can be formally proved. It is well known that standard recurrent neural networks are not distribution independent learnable in the probably approximately correct (PAC) sense if arbitrary precision and inputs are considered. We prove that recurrent networks with contractive transition function with a fixed contraction parameter fulfill the so-called distribution independent uniform convergence of empirical distances property and hence, unlike general recurrent networks, are distribution independent PAC learnable.

Charge distribution as a tool to investigate structural details. II. Extension to hydrogen bonds, distorted and hetero-ligand polyhedra

It is shown that one of the main reasons for most failures of the methods for calculating distance-dependent bond strengths is related to the distortion of the coordination polyhedra. The charge distribution (CD) method which depends on only one universal empirical parameter (contraction parameter) is modified to include: (i) an iterative calculation of the effective coordination number (ECoN), to deal with structures containing very distorted coordination polyhedra; (ii) a specific contraction parameter to treat structures containing any type of hydrogen bond; (iii) scale factors for coordination subshells, to treat structures with hetero-ligand polyhedra. The contraction parameter for the hydrogen bonds was obtained from 119 well refined structures based on neutron diffraction data. Examples of the application of the iterative charge distribution (CD-IT) are presented to show the efficiency of the new method in dealing with distorted (including hydrogen bonding) and hetero-ligand polyhedra. In particular, analysis of a series of 74 structures with pentacoordinated cations shows that deviations from overall trends are related to structure instability. The possible failure of the method with polyionic structures and `dynamic' structures is discussed.

Characteristics of Miniature Short-Tube Orifice Flows

This paper presents the results of an experimental investigation into the flow characteristics of miniature short-tube orifices of a type commonly used for fuel injection. From measurements of differential pressure and volumetric discharge it is shown that these devices are susceptible to a cavitation-induced instability phenomenon known as hydraulic flip. It was found that this instability is limited to orifices of length less than fourteen diameters and occurs at a critical pressure differential which varies as a function of the orifice l/d ratio and contraction parameter β. In addition, the performance of the device is examined in terms of the head loss characteristics and it is shown that the mechanisms associated with hydraulic flip have a significant effect on the efficiency of discharge.