DSMC investigation of rarefied gas flow through diverging micro- and nanochannels

Direct simulation Monte Carlo (DSMC) method with simplified Bernoulli-trials (SBT) collision scheme has been used to study the rarefied pressure-driven nitrogen flow through diverging microchannels. The fluid behaviours flowing between two plates with different divergence angles ranging between 0$^{\circ}$ to 17$^{\circ}$ are described at different pressure ratios (1.5${\le}{\prod}{\le}$2.5) and Knudsen numbers (0.03${\le}$Kn${\le}$12.7). The primary flow field properties, including pressure, velocity, and temperature, are presented for divergent microchannels and are compared with those of a microchannel with a uniform cross-section. The variations of the flow field properties in divergent microchannels, which are influenced by the area change, the channel pressure ratio and the rarefication are discussed. The results show no flow separation in divergent microchannels for all the range of simulation parameters studied in the present work. It has been found that a divergent channel can carry higher amounts of mass in comparison with an equivalent straight channel geometry. A correlation between the mass flow rate through microchannels, the divergence angle, the pressure ratio, and the Knudsen number has been suggested. The present numerical findings prove the occurrence of Knudsen minimum phenomenon in micro- and Nano- channels with non-uniform cross-sections.Comment: Accepted manuscript; 25 Pages and 11 Figures; "Microfluidics and Nanofluidics

Effect of chitosan oligosaccharide and valine on growth, serum hormone levels and meat quality of broilers

Chitosan oligosaccharide (COS) and valine (Val) supplementation will improve growth performance, carcass traits, hormonal profile and meat quality in broilers. To evaluate this hypothesis, based on a 2×4 factorial arrangement, 480 male broilers (Ross 708) were randomly placed in eight treatment groups for two levels of COS (C1: 100 mg/kg, and C2: 150 mg/kg) and four levels of valine (V1: 0.57%, V2: 0.72%, V3: 0.87% and V4: 1.02%) with three replicates (n=24) with 20 birds in each (ni=60; i=1, 2, 3,..., 8.). The results showed that live bodyweight (BW), weight gain (WG), and carcass weight increased, and feed conversion ratio (FCR) decreased with increased supplemental levels of dietary Val at C1 and C2. Abdominal fat reduced linearly for both COS and Val, with a higher reduction response value at C2 and V4. The serum levels of triiodothyronine (T3), thyroxine (T4), testosterone and insulin-like growth factor 1 (IGF-1) presented a linear effect for COS and Val. The proximate composition of breast and leg meat showed that crude fat content decreased linearly for COS and Val with higher reduction response values at V3 for both levels of COS. The ash content rose linearly with increasing concentration of Val at C1, but showed the highest value at V2 when birds were offered C2. There was an interaction between COS and Val for T3, T4, IGF-1, ash content and crude fat. In conclusion, supplementation exerted a significant influence on the growth performance, hormonal profile and meat composition of broilers

Neural Lyapunov Control

We propose new methods for learning control policies and neural network Lyapunov functions for nonlinear control problems, with provable guarantee of stability. The framework consists of a learner that attempts to find the control and Lyapunov functions, and a falsifier that finds counterexamples to quickly guide the learner towards solutions. The procedure terminates when no counterexample is found by the falsifier, in which case the controlled nonlinear system is provably stable. The approach significantly simplifies the process of Lyapunov control design, provides end-to-end correctness guarantee, and can obtain much larger regions of attraction than existing methods such as LQR and SOS/SDP. We show experiments on how the new methods obtain high-quality solutions for challenging control problems.Comment: NeurIPS 201

Dependent Nonparametric Bayesian Group Dictionary Learning for online reconstruction of Dynamic MR images

In this paper, we introduce a dictionary learning based approach applied to the problem of real-time reconstruction of MR image sequences that are highly undersampled in k-space. Unlike traditional dictionary learning, our method integrates both global and patch-wise (local) sparsity information and incorporates some priori information into the reconstruction process. Moreover, we use a Dependent Hierarchical Beta-process as the prior for the group-based dictionary learning, which adaptively infers the dictionary size and the sparsity of each patch; and also ensures that similar patches are manifested in terms of similar dictionary atoms. An efficient numerical algorithm based on the alternating direction method of multipliers (ADMM) is also presented. Through extensive experimental results we show that our proposed method achieves superior reconstruction quality, compared to the other state-of-the- art DL-based methods

Population Dynamic And Effects Of The Invasive Species Ctenophore Mnemiopsis Leidyi In The Southern Caspian Sea

In this study, M. leidyi population, plankton abundance, biomass and species composition and interaction between environmental and biological characteristics were evaluated in the Iranian coasts of the Caspian Sea from 2001 until 2006. Dalam kajian ini, populasi M. leidyi, kelimpahan plankton, biojisim dan komposisi spesies serta interaksi antara persekitaran dan aspek biologi telah dikaji di persisiran pantai Laut Caspian, Iran pada tahun 2001 hingga 200

Knudsen pump inspired by Crookes radiometer with a specular wall

A rarefied gas is considered in a channel consisting of two infinite parallel plates between which an evenly spaced array of smaller plates is arranged normal to the channel direction. Each of these smaller plates is assumed to possess one ideally specularly reflective and one ideally diffusively reflective side. When the temperature of the small plates differs from the temperature of the sidewalls of the channel, these boundary conditions result in a temperature profile around the edges of each small plate which breaks the reflection symmetry along the channel direction. This in turn results in a force on each plate and a net gas flow along the channel. The situation is analysed numerically using the direct simulation Monte Carlo (DSMC) method and compared with analytical results where available. The influence of the ideally specularly reflective wall is assessed by comparing with simulations using a finite accommodation coefficient at the corresponding wall. The configuration bears some similarity with a Crookes radiometer, where a non-symmetric temperature profile at the radiometer vanes is generated by different temperatures on each side of the vane, resulting in a motion of the rotor. The described principle may find applications in pumping gas on small scales driven by temperature gradients