Analysis of Topological Chaos in Ghost Rod Mixing at Finite Reynolds Numbers Using Spectral Methods

The effect of finite Reynolds numbers on chaotic advection is investigated for two dimensional lid-driven cavity flows that exhibit topological chaos in the creeping flow regime. The emphasis in this endeavor is to study how the inertial effects present due to small, but non-zero, Reynolds number influence the efficacy of mixing. A spectral method code based on the Fourier-Chebyshev method for two-dimensional flows is developed to solve the Navier-Stokes and species transport equations. The high sensitivity to initial conditions and the exponentional growth of errors in chaotic flows necessitate an accurate solution of the flow variables, which is provided by the exponentially convergent spectral methods. Using the spectral coefficients of the basis functions as solved through the conservation equations, exponentially accurate values of velocity everywhere in the flow domain are obtained as required for the Lagrangian particle tracking. Techniques such as Poincare maps, the stirring index based on the box counting method, and the tracking of passive scalars in the flow are used to analyze the topological chaos and quantify the mixing efficiency

A THREE-PHASE HIGH POWER FACTOR TWO-SWITCH BUCKTYPE CONVERTER

The paper proposes a three phase, two switch buck type converter with high power factor.The key feature of the proposed converter is that a switch in the converter has a lower peak voltage stress than a switch in a conventional threephase, single-switch buck-converter. A switch in the converter sees a line to neutral voltage across it rather than a line to line voltage which is the case for the switch in the conventional converter. The voltage stress in the proposed converter is limited to the peak value of the phase voltage of the input capacitors rather than the peak value of the line-to-line voltage, as is the case in the conventional converter. Since a switch in the proposed converter sees a line to neutral voltage instead of a line to line voltage the peak voltage stress is almost half than that of the switch in the conventional converter as this stress is reduced by a factor of sqrt(3). This reduces switching losses and allows lower rated standard devices to be used in converters. In the paper, the operation of the proposed converter is given and general considerations that should be taken into account when trying to design it are discussed. The feasibility of the converter is confirmed with results obtained from computer simulation and from an experimental prototype

Studies on mechanical behavior of glass epoxy composites with induced defects and correlations with NDT characterization parameters

Degradation in mechanical properties (compression, flexural and ILS) of glass epoxy composite laminates with induced defects (simulating delaminations) was studied. The defects were characterized by using the A-scan ultrasonic pulse-echo technique. The two A-scan parameters, viz. the back wall echo amplitude and time of flight, were followed respectively, as functions of the defect size (diameter) and its location in the laminate thickness. The mechanical properties of laminates were evaluated destructively for different defect sizes and locations. An attempt has been made to express the mechanical properties in terms of the two NDT scan parameters characterizing the defects and empirical equations presente

Plasma flows in the cool loop systems

We study the dynamics of low-lying cool loop systems for three datasets as observed by the Interface Region Imaging Spectrograph (IRIS). Radiances, Doppler shifts and line widths are investigated in and around observed cool loop systems using various spectral lines formed between the photosphere and transition region (TR). Footpoints of the loop threads are either dominated by blueshifts or redshifts. The co-spatial variation of velocity above the blue-shifted footpoints of various loop threads shows a transition from very small upflow velocities ranging from (-1 to +1) km/s in the Mg\,{\sc ii} k line (2796.20~\AA; formation temperature: log (T/K) = 4.0) to the high upflow velocities from (-10 to -20) km/s in Si\,{\sc iv}. Thus, the transition of the plasma flows from red-shift (downflows) to the blue-shift (upflows) is observed above the footpoints of these loop systems in the spectral line C\,{\sc ii} (1334.53~\AA; \log (T/K) = 4.3) lying between Mg\,{\sc ii} k and Si\,{\sc iv} (1402.77~\AA; log (T / K) = 4.8). This flow inversion is consistently observed in all three sets of the observational data. The other footpoint of loop system always remains red-shifted indicating downflowing plasma. The multi-spectral line analysis in the present paper provides a detailed scenario of the plasma flows inversions in cool loop systems leading to the mass transport and their formation. The impulsive energy release due to small-scale reconnection above loop footpoint seems to be the most likely cause for sudden initiation of the plasma flows evident at TR temperatures.Comment: 29 Pages, 14 figures, The Astrophysical Journal (in press

Luminescent Ag<SUB>7</SUB> and Ag<SUB>8</SUB> clusters by interfacial synthesis

Interfacial etching of silver nanoparticles and separation of the products by polyacrylamide gel electrophoresis afforded Ag8 and Ag7 clusters with red and blue-green fluorescence emission, respectively (see picture). The strongly temperature-dependent emission of the clusters suggests potential applications, whilst their facile phase transfer to organic media facilitates further studies

Microbiological Quality of Meat Collected from Municipal Slaughter Houses and Retail Meat Shops from Hyderabad Karnataka Region, India

AbstractIn the present research work, 300 meat samples (50 beef, 50 carabeef, 50 chevon, 50 mutton, 50 pork and 50 chicken) collected from the municipal slaughter houses and the retail meat shops from Hyderabad Karnataka region of Karnataka state, India, were analyzed for the microbiological quality; standard plate count and isolation and confirmation of Staphylococcus, Salmonella, E. Coli, Listeria and Clostridium by selective plating, microscopic examination and biochemical characterization. As per Food Safety and Standards (FSS) regulations 2011, of the samples analyzed, 89 (29.66%) (21 beef, 26 carabeef, 9 chevon, 7 mutton, 14 pork and 7 chicken) samples exceeded the limit of 10,000 CFU/gram of total viable count. Twenty (6.66%) samples (8 beef, 9 carabeef and 3 pork) exceeded the limit for Staphylococcus (100/gram maximum), 15 (5%) samples (9 pork, 4 chicken and 2 mutton) exceeded the limit for Salmonella (absent in 25 gram) and 22 (7.33%) samples (11 pork, 4 chicken, 4 beef and 3 carabeef) exceeded the limit for E. Coli (100/gram maximum). None of the samples were positive for Listeria and Clostridium spp. The finding in this study specifies the probable contamination during farming and on-floor slaughtering and accentuates the requirement of the upgrading the municipal slaughter houses and training of retail outlet sellers

Comparison of Design Procedures for Pre Engineering Buildings (PEB): A Case Study

In recent years, the introduction of Pre Engineered Building (PEB) concept in the design of structures made & designs in a much optimized way. The adoptability of PEB in the place of conventional steel building (CSB) design concept resulted many advantages including economy and easier fabrication. In this study, an industrial structure (Ware House) is analyzed & designed according to the Indian standards IS 800-1984, IS 800-2007 and also by referring MBMA-96 and AISC-89. In this study a structure span 40m, length= 187m with clear height 8m and has R-Slope 1:1, analyzes and design is carried out considering 2D frames (End frame, frame without crane and frame with 3 module cranes). The economy of the structure is discussed in terms of its weight comparison between (MBMA-96, IS800-2007), (MBMA-96, IS800-1944) & (IS800-1984, IS800-2007)