Research into Dry Turning of Welded Surface by Replaceable Cutting Insert with Closed Loop Heat Removal

A special tool has been devised incorporating a closed loop system based on Peltier thermoelectric couples to cool replaceable hard alloy inserts. Experimental research has been done into dry turning of a X20Cr13 steel welded surface with a SECO cubic boron nitride circular plate at the cutting speed increasing from 100 to 300 m/min. It has been determined that Ra surface roughness decreases by 22% while Rz surface roughness goes down by 26%; in addition, the wear flat of tool tips diminishes by 17%. © 2018 Published under licence by IOP Publishing Ltd.The work was supported by Ministry of Education and Science of the Russian Federation, contract № 02.G25.31.0148 with Sverdlovsk Instrumental Plant within the framework of Research and Development Project No Н979.210.007/15, July 28, 2015 for the federal autonomous educational institution of higher education “Ural Federal University”

Observation of vortex dipoles in an oblate Bose-Einstein condensate

We report experimental observations and numerical simulations of the formation, dynamics, and lifetimes of single and multiply charged quantized vortex dipoles in highly oblate dilute-gas Bose-Einstein condensates (BECs). We nucleate pairs of vortices of opposite charge (vortex dipoles) by forcing superfluid flow around a repulsive gaussian obstacle within the BEC. By controlling the flow velocity we determine the critical velocity for the nucleation of a single vortex dipole, with excellent agreement between experimental and numerical results. We present measurements of vortex dipole dynamics, finding that the vortex cores of opposite charge can exist for many seconds and that annihilation is inhibited in our highly oblate trap geometry. For sufficiently rapid flow velocities we find that clusters of like-charge vortices aggregate into long-lived dipolar flow structures.Comment: 4 pages, 4 figures, 1 EPAPS fil

ESTIMATION OF GAS EXCHANGE INDICATORS AT 3-D MODELING OF THE WORKING PROCESS OF THE TWO-STROKE PETROL ENGINE

With the help of 3-D modeling of the workflow of a two-stroke engine with spark ignition, crank-chamber scavenging and a carburetor feeding system in the modes of external speed characteristic the indices of gas exchange were evaluated. The simulation results are consistent with the experimental data and 3D simulation results in the AVL FIRE and MTFS® software complexes. The model allows performing optimized calculations of multiphase flow in ICE during experimental design work

ОЦІНКА ПОКАЗНИКІВ ГАЗООБМІНУ ПРИ 3D-МОДЕЛЮВАННІ РОБОЧОГО ПРОЦЕСУ ДВОТАКТНОГО БЕНЗИНОВОГО ДВИГУНА

With the help of 3-D modeling of the workflow of a two-stroke engine with spark ignition, crank-chamber scavenging and a carburetor feeding system in the modes of external speed characteristic the indices of gas exchange were evaluated. The simulation results are consistent with the experimental data and 3D simulation results in the AVL FIRE and MTFS® software complexes. The model allows performing optimized calculations of multiphase flow in ICE during experimental design work.С помощью 3D-моделирования рабочего процесса двухтактного двигателя с искровым зажиганием, кривошипно-камерной продувкой и карбюраторной системой питания на режимах внешней скоростной характеристики оценены показатели газообмена. Результаты моделирования согласуются с экспериментальными данными и результатами 3D-моделиро­вания в программных комплексах AVL FIRE и MTFS®. За допомогою 3D-моделювання робочого процесу двотактного двигуна з іскровим запалюванням, кривошипно-камерною продувкою і карбюраторною системою живлення на режимах зовнішньої швидкісної характеристики оцінено показники газообміну. Результати моделювання узгоджуються з експериментальними даними і результатами 3D-моделювання у програмних комплексах AVL FIRE і MTFS®

Eddies in the Red Sea as seen by satellite SAR imagery

peer reviewedWe present the results of our observations of mesoscale and sub-mesoscale eddies in the Red Sea based on synthetic aperture radar (SAR) imagery. The dataset used includes about 500 Envisat Advanced SAR (ASAR) images obtained in 2006-2011 over the Red Sea. We found more than 1000 sub-mesoscale eddies, which manifest in the SAR imagery both due to surfactant films (“black” eddies) and wave/current interactions (“white” eddies), depending on the local wind speed. Sub-mesoscale eddies in the Red Sea seem to be more innumerous than in other inner seas, presumably due to a relatively deep upper mixed layer in this basin. Moreover, more than 50 meso- and basin-scale eddies were found, whose rotation was mostly anti-cyclonic and whose diameters ranged up to approx. 200 km. Most of the basin-scale eddies were found between 21°N and 24°N, which is in agreement with earlier observations and with numerical modeling

Evolution of an isolated region in a stratified fluid

This paper reports an experimental study on the evolution of an isolated turbulent region in an otherwise quiescent linearly stratified fluid. A turbulent patch was generated by pulsed horizontal injection of a small volume of fluid. It was found that the turbulent blob thus produced initially grows as in a nonstratified fluid for a nondimensional time period of Nt ˜ 4 – 5 (with N the buoyancy frequency), attains a maximum height, and then physically collapses slowly to form a planar, quasi-two-dimensional dipole pattern. The timescale for the physical collapse of the blob was found to be much larger than that of the turbulence collapse. Scaling arguments are presented to explain the evolution of the turbulent region, and the experimental results are compared with the model predictions