In-place rotation of particles and time-average vibrational vortex on a Chladni plate

2021 ◽  
pp. 101493
Author(s):  
Zhitao Zhou ◽  
Zewei Hou ◽  
Yongmao Pei
Keyword(s):  
Time Average

Breakthrough on Routine Service Cycle Time Improvement – Leap Frog Concept, Duri Field, Indonesia

2020 ◽  
Author(s):  
R. Irawan
Keyword(s):  
Cycle Time ◽  
Critical Path ◽  
Well Control ◽  
Routine Service ◽  
New Process ◽  
Work Concept ◽  
Preparation Step ◽  
One Step ◽  
Time Average ◽  
Moving Process

Leap frog concept was created to address the loss of single joint rig agility and drive the cycle time average lower than ever. The idea is to move the preparation step into a background activity that includes moving the equipment, killing the well, dismantling the wellhead and installing the well control equipment/BOP before the rig came in. To realize the idea, a second set of equipment is provided along with the manpower. By moving the preparation step, the goal is to eliminate a 50% portion of the job from the critical path. The practice is currently performed in tubing pump wells on land operations. However, the work concept could be implemented for other type of wells, especially ESP wells. After implementation, the cycle time average went down from 18 hours to 11 hours per job, or down by ~40%. The toolpusher also reports more focused operations due to reduced scope and less crew to work with, making the leap frog operation safer and more reliable. Splitting the routine services into 2 parts not only shortened the process but it also reduces noise that usually appear in the preparation process. The team are rarely seen waiting on moving support problems that were usually seen in the conventional process. Having the new process implemented, the team had successfully not only lowered cycle time, but also eliminated several problems in one step. Other benefits from leap frog implementation is adding rig count virtually to the actual physical rig available on location, and also adding rig capacity and completing more jobs compared to the conventional rig. In other parts, leap frog faced some limitation and challenges, such as: limited equipment capability for leap frog remote team to work on stuck plunger, thus hindering its leap frog capability, and working in un-restricted/un-clustered area which disturb the moving process and operation safety.

mMedia: An Efficient Transmission Policy for Multimedia Applications using Mobile Cloud Computing

2019 ◽  
Vol 9 (1) ◽  
pp. 32-42 ◽  
Author(s):  
Rajesh Kumar Verma ◽  
Chhabi Rani Panigrahi ◽  
Bibudhendu Pati ◽  
Joy Lal Sarkar
Keyword(s):  
Cloud Computing ◽  
Mobile Cloud Computing ◽  
Optimization Technique ◽  
Multimedia Applications ◽  
Mobile Cloud ◽  
The People ◽  
Rich Media ◽  
Time Average ◽  
Audio Video ◽  
Efficient Transmission

Background & Objective: Multimedia aggregates various types of media such as audio, video, images, animations, etc., to form a rich media content which produces an everlasting effect in the minds of the people. Methods: In order to process multimedia applications using mobile devices, we encounter a big challenge as these devices have limited resources and power. To address these limitations, in this work, we have proposed an efficient approach named as mMedia, wherein multimedia applications will utilize the multi cloud environment using Mobile Cloud Computing (MCC), for faster processing. The proposed approach selects the best available network. The authors have also considered using the Lyapunov optimization technique for efficient transmission between the mobile device and the cloud. Results: The simulation results indicate that mMedia can be useful for various multimedia applications by considering the energy delay tradeoff decision. Conclusion: The results have been compared alongside the base algorithm SALSA on the basis of different parameters like time average queue backlog, delay and time average utility and indicate that the mMedia outperforms in all the aspects.

The ‘preferred mode’ of the axisymmetric jet

1981 ◽  
Vol 110 ◽  
pp. 39-71 ◽  
Author(s):  
A. K. M. F. Hussain ◽  
K. B. M. Q. Zaman
Keyword(s):  
Reynolds Number ◽  
Reynolds Stress ◽  
Coherent Structure ◽  
Large Scale ◽  
Near Field ◽  
Saddle Points ◽  
Initial Boundary ◽  
Phase Average ◽  
Background Turbulence ◽  
Time Average

The ‘preferred mode’ of an incompressible axisymmetric free jet has been organized through controlled perturbation, and spatial distributions of time-average as well as phase-average flow properties in the near field are documented. The excitation produces noticeable changes in the time-average measures of the jet, although these changes are less dramatic than those for the excitation producing stable vortex pairing. For different stages in the evolution of the preferred-mode coherent structure, the phase-average vorticity, coherent Reynolds stress, and incoherent turbulence intensities and Reynolds stress have been educed through phase-locked hot-wire measurements, over the spatial extent of the structure and without invoking the Taylor hypothesis. For a particular stage of the evolution (i.e. when the structure is centred at x/D ≃ 3) the distributions of these quantities have been compared for both initially laminar and fully turbulent exit boundary layers, and for four jet Reynolds numbers. The relative merits of the coherent structure streamline and pseudo-stream-function patterns, as compared with phase-average velocity contours, for structure boundary identification have been discussed. The structure shape and size agree closely with those inferred from the average streamline pattern of the natural structure educed by Yule (1978).These data as well as τ-spectra show that even excitation at the preferred mode cannot sustain the initially organized large-scale coherent structure beyond eight diameters from the jet exit. The background turbulence is organized by the coherent motions in such a way that the maximum rate of decrease of the coherent vorticity occurs at the structure centres which are the saddle points of the background-turbulence Reynolds-stress distributions. The structure centres are also the locations of peak phase-average turbulence intensities. The evolving shape of the structure as it travels downstream helps explain the transverse variations of the wavelength and convection velocity across the mixing layer. The coherent structure characteristics are found to be independent of whether the initial boundary layer is laminar or turbulent, but depend somewhat on the jet Reynolds number. With increasing Reynolds number, the structure decreases in the streamwise length and increases in the radial width and becomes relatively more energetic, and more efficient in the production of coherent Reynolds stress.

The Effects of Modulation on an RF Discharge in Silane and on the Deposited a-Si:H

1987 ◽  
Vol 98 ◽  
Author(s):  
L. J. Overzet ◽  
J. T. Verdeyen ◽  
R. M. Roth ◽  
F. F. Carasco
Keyword(s):  
Electron Density ◽  
Average Power ◽  
Optical Emission ◽  
Rf Discharge ◽  
Absorption Coefficients ◽  
Average Value ◽  
Optical Bandgaps ◽  
Time Average ◽  
Substrate Temperatures ◽  
Attachment Process

ABSTRACTThe time evolution of the electron density and the optical emission intensity in response to a square wave modulated RF excitation of helium-silane mixtures has been studied and compared to that for the more conventional CW discharge. In addition, the films deposited from CW and modulated RF glows have-been compared on the basis of absorption coefficients and photoconductivities. Films deposited from modulated glows at substrate temperatures below 200°C have significantly smaller optical bandgaps than those deposited from comparable CW discharges. The bulk electron density in the modulated discharge undergoes a complex temporal variation and its time average value can be significantly larger than that in the CW glow despite the lower average power. A dissociative attachment process involving silane radicals, SiHn (n = 1 to 3), is identified as the most probable cause.

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