A method of measuring the critical jet pressure of clay cutting by a moving jet

2017 ◽  
pp. 77-83
Author(s):  
L. Gu ◽  
F.S. Ni ◽  
Z.S. Li ◽  
L.Q. Xu
Keyword(s):  
Moving Jet

Radio jets at high red shift

1986 ◽  
Vol 64 (4) ◽  
pp. 445-448 ◽  
Author(s):  
Colin J. Lonsdale
Keyword(s):  
Red Shift ◽  
Radio Sources ◽  
Present Sample ◽  
Radio Jets ◽  
Flow Speeds ◽  
Relativistic Flow ◽  
Moving Jet ◽  
Luminosity Evolution ◽  
Radio Quasar ◽  
Observational Program

Using preliminary results from a large observational program targeting high red-shift radio quasars, we have increased the total number of radio jets known beyond a red shift of 1.5 from 5 to 26, thus generating one of the most uniform and complete samples of radio jets in existence. This sample enjoys relative freedom from cosmological and luminosity-evolution effects, which normally complicate statistical analyses of jets.An attempt has been made to test a type of radio-quasar model in which the appearance of a radio source is strongly influenced by its orientation relative to the line of sight, owing to Doppler boosting of the emission from relativistically moving jet material. Four "orientation indicators" are isolated, which should all be correlated with each other to some degree if the above-mentioned model is correct. It is found that only one pair of parameters shows a significant correlation, namely the jet prominence (relative to the lobes) and the jet curvature. This particular correlation finds a natural explanation in the physics of radio sources, and therefore may not be due to orientation effects.As a result of these findings, it is concluded that the present sample of high red-shift jets shows no evidence of relativistic flow speeds on kiloparsec scales.

scholarly journals Fabrication of Beltlike Fibers by Electrospinning

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1087 ◽  
Author(s):  
Yan-Qing Liu ◽  
Chun-Hui He ◽  
Xiao-Xia Li ◽  
Ji-Huan He
Keyword(s):  
Surface Tension ◽  
Polyethylene Glycol ◽  
Theoretical Analysis ◽  
Minimal Surface ◽  
Crystallite Size ◽  
Zro2 Nanoparticles ◽  
One Dimensional ◽  
Theoretical Predictions ◽  
Spinning Process ◽  
Moving Jet

Electrospinning is always used to fabricate one-dimensional nanofibers. Cylindrical fibers are formed during the spinning process due to the minimal-surface principle. However, when the moving jet has high rigidity, which can counteract the surface tension for a minimal surface, beltlike fibers can be obtained. Using the Hall–Petch effect, the rigidity of the moving jet can be greatly enhanced by adding nanoparticles. Polyethylene glycol with a nanometric crystallite size of 4 nm and ZrO2 nanoparticles are used as additives in the experiment, a theoretical analysis is carried out, and the theoretical predictions are verified experimentally.

scholarly journals Vibration of an axially moving jet in a dry spinning process

2019 ◽  
Vol 38 (3-4) ◽  
pp. 1125-1131 ◽  
Author(s):  
Li Zhang ◽  
Zhanping Yang ◽  
Xiaomin Feng ◽  
Jianhua Cao ◽  
Tao Yu ◽  
...  
Keyword(s):  
Dry Spinning ◽  
Spinning Process ◽  
Moving Jet ◽  
Axially Moving

scholarly journals Monthly VLBI Monitoring of Selected Gamma-Bright Quasars

1998 ◽  
Vol 164 ◽  
pp. 43-44 ◽  
Author(s):  
S. Britzen ◽  
A. Witzel ◽  
T.P. Krichbaum ◽  
J. Roland ◽  
S.J. Wagner
Keyword(s):  
Structural Changes ◽  
Gamma Ray ◽  
High Time Resolution ◽  
Radio Sources ◽  
High Frequencies ◽  
Geodetic Vlbi ◽  
High Energies ◽  
The Past ◽  
Curved Trajectories ◽  
Moving Jet

AbstractIn the past few years EGRET observations of extragalactic radio sources demonstrated the presence of blazars at high energies and supplied informations about their enormous luminosities. Questions arose whether outbursts at these high frequencies can be linked to structural changes in the radio regime and the need for VLBI monitoring became obvious. In the past two decades geodetic VLBI measurements gathered this kind of data.We analyzed λ =3.6 cm observations with high time-resolution (up to once a month) from the geodetic IRIS campaigns for the γ-ray active quasars PKS 0420-014 and PKS 0528+134. In both sources superluminally moving jet components could be traced over time periods of several years on curved trajectories. Both sources exhibit component ejections preceding the time of an observed gamma-ray flaring.

Experiments on Dicing Monocrystalline Silicon Wafer Using Micro Abrasive Water Jet

2011 ◽  
Vol 287-290 ◽  
pp. 2863-2868 ◽  
Author(s):  
Yu Yong Lei ◽  
Dai Jun Jiang ◽  
Ke Fu Liu ◽  
Pu Hua Tang
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Silicon Wafer ◽  
Flow Rate ◽  
Feed Rate ◽  
Water Jet ◽  
Monocrystalline Silicon ◽  
Abrasive Water Jet ◽  
Feed System ◽  
Moving Jet

The experiments on dicing monocrystalline silicon wafer using micro abrasive water jet turning were performed. A specifically designed water jet machine tool with four axes was developed and a specially designed cutting head has developed, in which the inside diameter of orifice and focusing tube is f125 mm and f500 mm respectively, while the silicon carbide solid abrasives with average diameter of 25-100 mm was used. In order to control the flow rate of micro abrasives precisely, an abrasive feed system with auger mechanism driven by DC motor reducer was used. The diameters of monocrystalline silicon bars are around 50 mm. Two basic turning methods, i.e. turning with stationary jet and turning with moving jet were applied. The preliminary experimental results such as kerf width, wafer thickness, surface quality etc. were analyzed. It was found that micro abrasive water jet can be used to precisely turn brittle materials like monocrystalline silicon. The turned wafer with thickness of 1 mm above could be achieved. A thinner wafer less than 1 mm is difficult to obtain during experiments because of cracking or chipping. Experiments demonstrate that the wafer surface has macro stripping characteristics similar to linear cutting. It was observed that there is less waviness and smooth surface on the turned wafer when with moving jet. And it depends greatly on the water jet pressure, feed rate of the jet, rotation speed of silicon bar, abrasive particle size as well as flow rate of abrasive. The detailed analysis indicates that the surface roughness of turned wafer with moving jet is around Ra 1.5-5.6 μm, while that of turned wafer with stationary jet is around Ra6.3 μm, when other conditions are same. The results show that surface quality turning with moving jet is obviously better than that of stationary jet. Smaller surface roughness of turned wafer could be obtained when finer abrasive is used. The experiment shows also that the wafer is typically tapered with either the stationary jet or moving jet. There is a concave on the turned surface when feed rate of the jet is too low or dwell time is too long. This is attributed to the jet rebound from one face to the other. Therefore there is an optimizing rotational speed during turning. This study indicates that dicing mono crystalline silicon wafer using micro abrasive water jet turning has potential application in semiconductor industry.

scholarly journals Asymmetric jet production in the active galactic nucleus of NGC 1052

2019 ◽  
Vol 623 ◽  
pp. A27 ◽  
Author(s):  
A.-K. Baczko ◽  
R. Schulz ◽  
M. Kadler ◽  
E. Ros ◽  
M. Perucho ◽  
...  
Keyword(s):  
Spectral Index ◽  
Jet Flows ◽  
Central Feature ◽  
Long Baseline ◽  
Inclination Angles ◽  
Moving Jet ◽  
Thick Absorber ◽  
Density Ratios ◽  
Very Long Baseline Array ◽  
Index Maps

Context. Few active galactic nuclei (AGN) reveal double-sided jet systems. However, these systems are crucial to understand basic physical properties of extragalactic jets. Aims. We address the questions whether jets in AGN are symmetric in nature, how well they are collimated on small scales, and how they evolve with time. Methods. We monitored the sub-parsec scale morphology of NGC 1052 with the Very Long Baseline Array at 43 GHz from 2005 to 2009. Results. A detailed study of 29 epochs show a remarkable asymmetry between both jets. A kinematic analysis of the outflows reveals higher apparent velocities for the eastern (approaching) jet as compared to the western (receding) jet, i.e., βej = 0.529 ± 0.038 and βwj = 0.343 ± 0.037, respectively. Contradictory to previous studies, we find higher flux densities for the western jet as compared to the eastern. The distribution of brightness temperature and jet width features well-collimated jets up to 1 mas distance to the dynamic center and a nearly conical outflow further outward. By combining flux density ratios and velocities of the jet flows, we were unable to find a combination of intrinsic velocities and inclination angles of the jets that is consistent for all four years of observation; this contradicts findings for symmetrically evolving jets. Spectral index maps between quasi-simultaneous 22 GHz and 43 GHz observations support the existence of an optically thick absorber covering the innermost ≃1.6 mas around the 43 GHz central feature and an optically thin jet emission with a spectral index of ≤−1. Conclusions. Our results fit into a picture in which we expect larger internal energy and/or magnetic flux in the western jet and higher kinetic energy in the eastern jet. Previous observations at lower frequencies have found slower velocities of the moving jet features as compared to this work. Considering the different velocities in different areas, we suggest a spine-sheath structure with a faster inner layer and slower outer layer.

scholarly journals Solitary waves on a ferrofluid jet

2014 ◽  
Vol 750 ◽  
pp. 401-420 ◽  
Author(s):  
M. G. Blyth ◽  
E. I. Părău
Keyword(s):  
Magnetic Field ◽  
Solitary Wave ◽  
Solitary Waves ◽  
Phase Speed ◽  
Bond Number ◽  
Azimuthal Magnetic Field ◽  
Weakly Nonlinear ◽  
Weakly Nonlinear Theory ◽  
Limiting Profile ◽  
Moving Jet

AbstractThe propagation of axisymmetric solitary waves on the surface of an otherwise cylindrical ferrofluid jet subjected to a magnetic field is investigated. An azimuthal magnetic field is generated by an electric current flowing along a stationary metal rod which is mounted along the axis of the moving jet. A numerical method is used to compute fully nonlinear travelling solitary waves, and the predictions of elevation waves and depression waves made by Rannacher and Engel (New J. Phys., vol. 8, 2006, pp. 108–123) using a weakly nonlinear theory are confirmed in the appropriate ranges of the magnetic Bond number. New nonlinear branches of solitary wave solutions are identified. As the Bond number is varied, the solitary wave profiles may approach a limiting configuration with a trapped toroidal-shaped bubble, or they may approach a static wave (i.e. one with zero phase speed). For a sufficiently large axial rod, the limiting profile may exhibit a cusp.

scholarly journals Performance of Hydrodynamics Flow on Flip Buckets Spillway for Flood Control in Large Dam Reservoirs

2020 ◽  
Vol 1 (1) ◽  
pp. 39-47
Author(s):  
Omid Aminoroayaie Yamini ◽  
Mohammad Reza Kavianpour ◽  
Azin Movahedi
Keyword(s):  
High Speed ◽  
Flood Control ◽  
Flow Characteristics ◽  
Human Consumption ◽  
Plunge Pool ◽  
Dam Reservoirs ◽  
Moving Jet ◽  
Industrial Use ◽  
High Head ◽  
Large Dam

Flip buckets are usually used in high head dams to dissipate the destructive energy of high speed jets. These structures are fixes at the end of the outlet conduits to direct the moving jet into the atmosphere. The process of energy dissipation also resumes, while the jet entering into its downstream plunge pool. Although studies of flow over flip buckets turn back to many years ago, but still there are uncertainties regarding the flow behaviour over these structures with various geometries and flow conditions. In this study, experimental measurements of static and dynamic pressures and their distribution over these structures are investigated. Measurements were made along two different simple flip buckets with various Froude numbers to determine the effects of the geometry and flow characteristics on pressure field. Maximum pressures are also presented and the results are compared with those of other investigations. The results of this study can be used to increase the safety of large dams that remain sustainable in the process of exploitation such as irrigation, human consumption, industrial use, aquaculture, and navigability. Doi: 10.28991/HEF-2020-01-01-05 Full Text: PDF

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