Skin friction drag reduction over staggered three dimensional cavities

The effect of three-dimensional staggered circular cavities on a zero-pressure gradient incompressible turbulent boundary layer was studied. Two key parameters were varied, being the ratio of the diameter, d, to the depth, h, of the cavity, d/h and the Reynolds number based on the diameter of the cavity, Rd. Velocity profile measurements showed that for the cases of d/h>1 an increase in skin friction drag was experienced with respect to a smooth surface, but for d/h≤1 the drag increment was almost negligible and in some cases it was lower than that of a smooth surface by up to 10%. Measurements along the spanwise plane showed the presence of organised transverse velocity components which bear some resemblance with the flow over riblets. The skin friction drag appears to be a strong function of Rd, where for Rd>5500 a drag increment is experienced which could potentially be due to shear layer breakdown and more production of turbulence

Study of detonation interactions inside a 2-D ejector using detonation transmission tubing

Study of detonation interactions inside a two-dimensional ejector using detonation transmission tubing was reported. The main objective of the ejector assembly in the study is to make the flow-field as close to 2-D as possible. Optical-grade Perspex sheets with a thickness of 10 mm were used on both sides of the nozzle to allow visualization of the flow. Wall pressure measurements were conducted at the locations. The NONEL tube was flush with the entrance of the nozzle. The signal to begin pressure measurements and image acquisition was obtained through a Kulite XT-190 transducer. The detonation was initiate by an electronic blasting machine, DynoStart 2, with a capacitance of 0.2μF and an output voltage of 2500 V. High-speed shadowgraphy was employed to visualize the flow. The results show that the effects of 3-D flow at the initial stage of the detonation affect the incident shock front and the reflected shock wave system at the nozzle entrance

समुद्री मोति संवर्धन तकनीक

मोति संवर्धन केलिए शुक्ति का चयन ; न्यूक्लियस का रोपण ; आदि प

Kinetics and mechanism of oxidation of chloramphenicol by 1-chlorobenzotriazole in acidic medium

Chloramphenicol (CAP) is an antibiotic drug having a wide spectrum of activity. The kinetics of oxidation of chloramphenicol by 1-chlorobenzotriazole (CBT) in HClO4 medium over the temperature range 293–323 K has been investigated. The reaction exhibits first-order kinetics with respect to [CBT]o and zero-order with respect to [CAP]o. The fractional-order dependence of rate on [H+] suggests complex formation between CBT and H+. It fails to induce polymerization of acrylonitrile under the experimental conditions employed. Activation parameters are evaluated. The observed solvent isotope effect indicates the absence of hydride transfer during oxidation. Effects of dielectric constant and ionic strength of the medium on the reaction rate have been studied. Oxidation products are identified. A suitable reaction scheme is proposed and an appropriate rate law is deduced to account for the observed kinetic data

Synaptic partner prediction from point annotations in insect brains

High-throughput electron microscopy allows recording of lar- ge stacks of neural tissue with sufficient resolution to extract the wiring diagram of the underlying neural network. Current efforts to automate this process focus mainly on the segmentation of neurons. However, in order to recover a wiring diagram, synaptic partners need to be identi- fied as well. This is especially challenging in insect brains like Drosophila melanogaster, where one presynaptic site is associated with multiple post- synaptic elements. Here we propose a 3D U-Net architecture to directly identify pairs of voxels that are pre- and postsynaptic to each other. To that end, we formulate the problem of synaptic partner identification as a classification problem on long-range edges between voxels to encode both the presence of a synaptic pair and its direction. This formulation allows us to directly learn from synaptic point annotations instead of more ex- pensive voxel-based synaptic cleft or vesicle annotations. We evaluate our method on the MICCAI 2016 CREMI challenge and improve over the current state of the art, producing 3% fewer errors than the next best method

On the temporal analysis of acoustic waves using schlieren imaging

The primary objective of the present study was to develop a quantitative schlieren-imaging technique that can be used to study the dynamics of instability waves. The technique was initially validated by optically capturing a controlled acoustic wave generated by a compression driver and excellent agreement was obtained with microphone measurements. An underexpanded jet was considered as an ideal test case due to the complexity and multitude of instability mechanism. Further analysis of the underexpanded jet demonstrated that this technique can be used to capture the very high frequency mode related to the phenomenon of screech

Development of a quantitative Schlieren imaging technicque for acoustic waves

The primary objective of the present work was the development of a quantitative schlieren-imaging technique that can be used to study the dynamics of instability waves. An underexpanded jet was considered as an ideal test case due to the complexity and multitude of instability mechanism. The technique was initially validated by optically capturing a controlled acoustic wave generated by a compression driver and excellent agreement was obtained with microphone measurements. Further analysis of an underexpanded jet demonstrated that the technique can be used to capture the very high screech frequency

Changes in moisture and energy fluxes due to agricultural land use and irrigation in the Indian Monsoon Belt

We present a conceptual synthesis of the impact that agricultural activity in India can have on land-atmosphere interactions through irrigation. We illustrate a “bottom up” approach to evaluate the effects of land use change on both physical processes and human vulnerability. We compared vapor fluxes (estimated evaporation and transpiration) from a pre-agricultural and a contemporary land cover and found that mean annual vapor fluxes have increased by 17% (340 km3) with a 7% increase (117 km3) in the wet season and a 55% increase (223 km3) in the dry season. Two thirds of this increase was attributed to irrigation, with groundwater-based irrigation contributing 14% and 35% of the vapor fluxes in the wet and dry seasons, respectively. The area averaged change in latent heat flux across India was estimated to be 9 Wm−2. The largest increases occurred where both cropland and irrigated lands were the predominant contemporary land uses

Probe of Spin Dynamics in Superconducting NbN Thin Films via Spin Pumping

The emerging field of superconductor (SC) spintronics has attracted intensive attentions recently. Many fantastic spin dependent properties in SC have been discovered, including the observation of large magnetoresistance, long spin lifetimes and the giant spin Hall effect in SC, as well as spin supercurrent in Josephson junctions, etc. Regarding the spin dynamic in SC films, few studies has been reported yet. Here, we report the investigation of the spin dynamics in an s-wave superconducting NbN film via spin pumping from an adjacent insulating ferromagnet GdN layer. A profound coherence peak of the Gilbert damping is observed slightly below the superconducting critical temperature of the NbN layer, which is consistent with recent theoretical studies. Our results further indicate that spin pumping could be a powerful tool for investigating the spin dynamics in 2D crystalline superconductors.Comment: 11 pages, 4 figures, and S

RELIABLE LOW-LATENCY VITERBI ALGORITHM ARCHITECTURES BENCHMARKED ON ASIC AND FPGA

The Viterbi formula is generally used in a variety of delicate use designs consisting of deciphering convolutional codes utilized in interactions such as satellite interaction, mobile relay, and also cordless lan. In addition, the formula has actually been related to automated speech acknowledgment and also storage space tools. In this thesis, reliable mistake discovery systems for styles based upon low-latency, low-complexity Viterbi decoders exist. The benefit of the suggested plans is that dependability needs, above resistance, as well as efficiency deterioration limitations are installed in the frameworks as well as can be adjusted appropriately. We likewise existing 3 versions of recomputing with inscribed operands as well as its adjustments to discover both short-term as well as long-term mistakes, paired with signature-based plans. The Viterbi formula is generally related to a variety of delicate use designs consisting of translating convolution codes made use of in interactions such as satellite interaction, mobile relay, and also cordless lan. Additionally, the formula has actually been put on automated speech acknowledgment as well as storage space tools