scholarly journals Effect of Scraper Geometry on Scraping HAP/ZrO2 Slurry in Digital Light Processing

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hai Gu ◽  
Jie Zhang ◽  
Jianhua Sun ◽  
Tiancheng Huang ◽  
Jie Jiang ◽  
...  
Keyword(s):  
Flow Velocity ◽  
External Force ◽  
Maximum Velocity ◽  
Bottom Surface ◽  
Velocity Change ◽  
Digital Light Processing ◽  
Velocity Peak ◽  
The Difference ◽  
Mixed Ceramic ◽  
Rounded Rectangle

Digital light processing (DLP) can be used to form HAP/ZrO2 mixed ceramic slurry. In the printing technology, the scraper geometry has an important effect on the scraping process; thus, it is necessary to conduct analysis. A modified lattice Boltzmann method (LBM) is proposed to conduct the numerical simulations according to the non-Newtonian behavior of the slurry. The Cross behavior of the slurry is viewed as a special external force; then, the traditional LBM including the true external force can be utilized effectively. The triangle, rectangle, trapezium, and rounded rectangle are the main considered section geometries of the scraper. When the flow velocity is set to 0.1 m/s, the results show that the maximum velocity occurs near the bottom surface of the scraper. In four situations, the velocity peak of the triangle case is 0.6270 m/s, which is the maximum, and much larger than the flow velocity of 0.1 m/s. The velocity peak of the rectangle case is 0.0466 m/s, which is the minimum. Although the velocity peak of the rounded rectangle case is 0.0556 m/s, the second velocity peak is 0.0465 m/s; the difference is smaller than that of the rectangle case. In addition, the streamlines figures show that the sharp corner leads to the obvious velocity change. In summary, the rounded rectangle is considered to be more suitable for scraping the HAP/ZrO2 mixed slurry.

Behavior of Unsteady Turbulent Starting Round Jets

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Neerav Abani ◽  
Jaal B. Ghandhi
Keyword(s):  
High Speed ◽  
Penetration Rate ◽  
Injection Rate ◽  
Injection Velocity ◽  
Time Varying ◽  
Velocity Change ◽  
Rate Of Penetration ◽  
Round Jets ◽  
The Difference ◽  
Sudden Decrease

Turbulent starting jets with time-varying injection velocities were investigated using high-speed schlieren imaging. Two solenoid-controlled injectors fed a common plenum upstream of an orifice; using different upstream pressures and actuation times, injection-rate profiles with a step increase or decrease in injection velocity were tested. The behavior of the jet was found to be different depending on the direction of the injection-velocity change. A step increase in injection velocity resulted in an increased rate of penetration relative to the steady-injection case, and a larger increase in injection velocity resulted in an earlier change in the tip-penetration rate. The step-increase data were found to be collapsed by scaling the time by a convective time scale based on the tip location at the time of the injection-velocity change and the difference in the injection velocities. A sudden decrease in injection velocity to zero was found to cause a deviation from the corresponding steady-pressure case at a time that was independent of the initial jet velocity, i.e., it was independent of the magnitude of the injection-velocity change. Two models for unsteady injection from the literature were tested and some deficiencies in the models were identified.

scholarly journals The non-Darcy characteristics of fault water inrush in karst tunnel based on flow state conversion theory

2021 ◽  
Vol 25 (6 Part B) ◽  
pp. 4415-4421
Author(s):  
Zheng-Zheng Cao ◽  
Yu-Feng Xue ◽  
Hao Wang ◽  
Jia-Rui Chen ◽  
Yu-Lou Ren
Keyword(s):  
Flow Velocity ◽  
Water Inrush ◽  
Coupled Model ◽  
Flow Fields ◽  
Darcy Law ◽  
Brinkman Equation ◽  
Flow State ◽  
Navier Stokes Equation ◽  
Velocity Change ◽  
Key Factor

The fault water inrush is a key factor which leads to tunnel construction in karst regions. Based on the fluid mechanics principles, the paper addresses a numer?ical coupled model for karst fault tunnel with COMSOL Multiphysics software. Besides, the Darcy law equation, Brinkman equation, and Navier-Stokes equation are inserted to stimulate the steady flow of aquifer, the non-linear seepage of fault and the free flow in tunnel excavating area in software, respectively. Then, the pres?sure and flow velocity in three flow fields are analyzed under different permeability ratios in numerical model. It is shown that the fault permeability is the key factor affecting water inrush, and that the pressure and flow velocity change visibly in adjacent domains between two flow fields.

Dependence of energy output on force generation during muscle contraction

1978 ◽  
Vol 235 (1) ◽  
pp. C20-C24 ◽  
Author(s):  
J. A. Rall
Keyword(s):  
Muscle Length ◽  
Maximum Velocity ◽  
Force Generation ◽  
Energy Output ◽  
Energy Liberation ◽  
Work Output ◽  
Extra Energy ◽  
Constant Distance ◽  
The Difference ◽  
Isometric Twitch

It has been proposed that the energy (heat + work) output of an isometric twitch is determined by the force that is generated under conditions of invariant activation, irrespective of muscle length. To test the effect of length and force on total energy output, muscles were stretched by increments beyond the muscle length at which twitch force is maximum (LO) and then stimulated; energy output and force then were measured. These data were compared with isovelocity twitches in which stimulated muscles, initially at different lengths, shortened (near maximum velocity) a constant distance and then redeveloped tension at lengths less than LO. If energy liberation was determined by force generation, plots of energy output versus force produced would be parallel with isovelocity twitches liberating extra energy as shortening heat. As predicted, the ratio of the slopes (n = 13) of these relations, 0.98 +/- 0.02, was not different from 1 and the shortening heat coefficient (alphaF/Pot, measured from the difference in intercepts), 0.15 +/- 0.01, was near to the expected value. Therefore, energy liberation in twitches appears to be uniquely determined by force generation and not by muscle length.

Evaluation and Analysis of Different Types of Prosthetic Knee Joint Used by above Knee Amputee

2020 ◽  
Vol 398 ◽  
pp. 34-40 ◽  
Author(s):  
Fahad Mohanad Kadhim ◽  
Jumaa Salman Chiad ◽  
Maryam Abdul Salam Enad
Keyword(s):  
Gait Cycle ◽  
Reaction Force ◽  
Maximum Velocity ◽  
Knee Joints ◽  
Von Mises Stress ◽  
Prosthetic Knee ◽  
Prosthetic Limb ◽  
Left And Right ◽  
The Difference ◽  
Von Mises

Four prosthetic knee joints (polycentric knee weight activating-4bar and friction, extension assist controlled),(single axis knee weight activating and friction, internal extension assist controlled), (single axis knee weight activating-4bar and hydraulically, controlled) and (polycentric knee geometric locking-6bar, hydraulically controlled) for a trans-femoral patient were tested. The tests were conducted to find the maximum velocity as well as discussing the most comfortable prosthetic forthe patient and walking stability for these prosthetic knees by examining the gait cycle and measuring the ground reaction force (GRF), using force a plate device. Also, the interface pressure was measured between socket and stump muscles by using F-socket device to get the stress distribution during walking with a prosthetic knee. Results manifested that the polycentric knee geometric locking - 6bar, hydraulically controlled is the best because of the good homogenous distribution of GRF between the healthy and prosthetic limb, during which the difference between both the healthy and prosthetic limb is with the least value (4%).And, K4 gives the minimum value of differences in contact pressure between the left and right limb with a value of (24%), it alsoimparts the maximum symmetry between the left and right limb according to the gait cycle parameters.The best results of the interface pressures and kinovea velocity are achieved whenK4 is used with (132.4KPa, 0.71m/s), respectively. Finally, the polycentric knee geometric locking - 6bar, hydraulically controlled is the best according to the ANSYS results during which it yields the minimum values of Von-Mises stress with 14.24MPa and a maximum factor of safety of 3.11.

scholarly journals Waves of Accelerated Motion in a Glacier Approaching Surge: the Mini-Surges of Variegated Glacier, Alaska, U.S.A.

1987 ◽  
Vol 33 (113) ◽  
pp. 27-46 ◽  
Author(s):  
Barclay Kamb ◽  
Hermann Engelhardt
Keyword(s):  
Flow Velocity ◽  
Pressure Wave ◽  
Water Pressure ◽  
Water System ◽  
Pressure Rise ◽  
Strain Wave ◽  
Overburden Pressure ◽  
Flow Acceleration ◽  
Accelerated Motion ◽  
Velocity Peak

AbstractPeriods of dramatically accelerated motion, in which the flow velocity increases suddenly from about 55 cm/d to a peak of 100–300cm/d and then decreases gradually over the course of a day, occurred repeatedly during June and July 1978–81 in Variegated Glacier (Alaska), a surging-type glacier that surged in 1982–83. These “mini-surges” appear to be related mechanistically to the main surge. The flow-velocity peak propagates down-glacier as a wave at a speed of about 0.3 km/h, over a reach of about 6 km in length. It is accompanied by a propagating pressure wave in the basal water system of the glacier, in which, after a preliminary drop, the pressure rises rapidly to a level greater than the ice-overburden pressure at the glacier bed, and then drops gradually over a period of 1–2 d, usually reaching a new low for the summer. The peak velocity is accompanied by a peak of high seismic activity due to widespread fresh crevassing. It is also accompanied by a rapid uplift of the glacier surface, amounting to 6–11 cm, which then relaxes over a period of 1–2 d. Maximum uplift rate coincides with the peak in flow velocity; the peak in accumulated uplift lags behind the velocity peak by 2 h. The uplift is mainly due to basal cavitation driven by the high basal water pressure, although the strain wave associated with the mini-surge motion can also contribute. Basal cavitation is probably responsible for the pulse of high turbidity that appears in the terminal outflow stream in association with each mini-surge. In the down-glacier reach, where the mini-surge waves are attenuating, the observed strain wave corresponds to what is expected for the propagating pulse in flow velocity, but in the reach of maximum mini-surge motion the strain wave has a form quite different, possibly related to special features in the mini-surge initiation process from that point up-stream. The flow acceleration in the mini-surges is due to enhanced basal sliding caused by the high basal water pressure and the consequent reduction of bed friction. A preliminary velocity increase shortly before the pressure wave arrives is caused by the forward shove that the main accelerated mass exerts on the ice ahead of it, and the resulting preliminary basal cavitation causes the drop in water pressure shortly before the pressure wave arrives. The mini-surge wave propagation is controlled by the propagation of the water-pressure wave in the basal water-conduit system. The propagation characteristics result from a longitudinal gradient (up-glacier increase) in hydraulic conductivity of the basal water system in response to the up-glacier increase of the basal water pressure in the mini-surge wave. The mini-surge waves are initiated in a succession of areas situated generally progressively up-glacier during the course of the summer season. In these areas, presumably, melt water that has accumulated in subglacial (?) reservoirs is released suddenly into the basal water system immediately below, generating a pressure rise that propagates down-stream from there. Relationships of the mini-surges to the main surge are seen in the role of high basal water pressure in causing the rapid glacier motion in both phenomena, in the pulse-propagation features of both, and in the high outflow turbidity associated with both. The mini-surges of Variegated Glacier have a strong resemblance to movement and uplift events observed in Unteraargletscher and Findelengletscher, Switzerland. This bears on the question whether the mini-surges are a particular characteristic of surge-type glaciers prior to surge.

The Threshold for Sudden Changes in the Velocity of a Seen Object

1950 ◽  
Vol 2 (1) ◽  
pp. 33-41 ◽  
Author(s):  
W. E. Hick
Keyword(s):  
Initial Velocity ◽  
Moving Objects ◽  
Significant Proportion ◽  
Difference Threshold ◽  
Experimental Conditions ◽  
Velocity Change ◽  
The Mean ◽  
The Difference ◽  
Velocity Changes ◽  
Method Of Constant Stimuli

The difference threshold for the velocity of a seen object was measured by the method of constant stimuli, using two categories. An approximate correspondence with Weber's law was found, the divergence from it appearing, in general, as an increase of the threshold at both ends of the range of initial velocities. The Mean Threshold (0·5 probability of perception, corrected for guessing) was, in favourable conditions, about 12 per cent, of the initial velocity. Whether the stimulus was an increase or a decrease of velocity made no marked difference. With two moving objects, which converged, crossed, and then diverged, both suffering the same change of velocity, the threshold was higher. Velocity changes as low as 2 · 5 per cent, elicited a significant proportion of correct responses. Some theoretical points in connection with this are discussed. Responses to blank stimuli showed a strong tendency to guess “slower,” which tendency differed significantly in degree between most of the experimental conditions. Tests with reduced exposure times showed that exposures could be as short as 0 · 5 second (the velocity change occurring in the middle of the exposure) without appreciable detriment.

Crystal-Axis-Rotation of Laser-Recrystallized Silicon on Insulator

1989 ◽  
Vol 164 ◽  
Author(s):  
K. Sugahara ◽  
T. Ippóshi ◽  
Y. Inoue ◽  
T. Nishimura ◽  
Y. Akasaka
Keyword(s):  
Thermal Conductivity ◽  
Laser Power ◽  
Rotation Angle ◽  
Defect Density ◽  
Silicon On Insulator ◽  
Bottom Surface ◽  
Crystal Axis ◽  
Scan Speed ◽  
The Difference ◽  
Axis Rotation

AbstractThe relation between the seed pitch and defect density of the laserrecrystallized SOI film was investigated. It was found that the defect density of the SOI increases as the seed pitch increases. The dependences of the laser scan speed and laser power on rotation angle of the SOI film were experimentally and numerically investigated. The crystal-axisrotation of the SOI film was considered to be due to the difference of the temperature between the top and bottom surface of the SOI film near the liquid-solid interface. A polysilicon heat sink structure with high thermal conductivity was newly proposed and was found to reduce the rotation in a small angle.

Pulmonary microcirculatory response to localized hypercapnia

1982 ◽  
Vol 53 (6) ◽  
pp. 1556-1564 ◽  
Author(s):  
T. Koyama ◽  
M. Horimoto
Keyword(s):  
Flow Velocity ◽  
Time Course ◽  
Capillary Flow ◽  
Mean Flow ◽  
Velocity Change ◽  
Luminal Diameter ◽  
Initial Values ◽  
Pulmonary Capillary ◽  
Before And After ◽  
Pulmonary Microvessels

Anesthetized bullfrogs were examined to study the effects of localized hypercapnia on the red blood cell (RBC) velocity in pulmonary alveolar microvessels on the exposed lung surface. Before and after the exposure of a small area of the lung surface 6 mm in diameter to a hypercapnic gas mixture, the region was exposed to CO2-free control gas. The RBC velocity was measured by the use of a laser Doppler microscope. Both mean flow velocity (MV) and pulsatile amplitude (PA) were determined from the resulting flow velocity contour. Responses of pulmonary microvessels to hypercapnia were examined by measuring the vessel diameters with an ocular microscale of the microscope while gas mixtures were applied to a 1-mm-diameter region of the surface. During hypercapnia both MV (2.31 +/- 0.27 mm/s) and PA (0.54 +/- 0.15 mm/s) in the alveolar arterioles (luminal diameter = 64 +/- 14 microns) were reduced, each reaching a minimum (2.01 +/- 0.24 and 0.43 +/- 0.19 mm/s, respectively) prior to gradual returns to their initial values. After reintroduction of the control gas, the values of MV and PA approached initial values more rapidly. In capillaries MV (1.44 +/- 0.18 mm/s) and PA (0.28 +/- 0.06 mm/s) decreased to 1.25 +/- 0.10 and 0.15 +/- 0.05 mm/s, respectively. The maximum reduction of PA (-44.6%) therefore clearly exceeded that of MV (-12.4%) in capillary flow. An analog model calculation suggested that the reduction in diameter of the arteriolar system could reduce PA more than MV in the pulmonary capillary network. The time course of the velocity change closely resembled that of the diameter change in relatively large arterioles. Vasoconstriction of the arterioles therefore appeared to be the major cause of these decrements in MV and PA.

Effect of denervation on ATP consumption rate of diaphragm muscle fibers

2007 ◽  
Vol 103 (3) ◽  
pp. 858-866 ◽  
Author(s):  
Gary C. Sieck ◽  
Wen-Zhi Zhan ◽  
Young-Soo Han ◽  
Y. S. Prakash
Keyword(s):  
Consumption Rate ◽  
Atp Hydrolysis ◽  
Maximum Velocity ◽  
Diaphragm Muscle ◽  
Single Type ◽  
Shortening Velocity ◽  
Cycling Rate ◽  
Cross Bridge ◽  
Atpase Reaction ◽  
The Difference

Denervation (DNV) of rat diaphragm muscle (DIAm) decreases myosin heavy chain (MHC) content in fibers expressing MHC2X isoform but not in fibers expressing MHCslow and MHC2A. Since MHC is the site of ATP hydrolysis during muscle contraction, we hypothesized that ATP consumption rate during maximum isometric activation (ATPiso) is reduced following unilateral DIAm DNV and that this effect is most pronounced in fibers expressing MHC2X. In single-type-identified, permeabilized DIAm fibers, ATPiso was measured using NADH-linked fluorometry. The maximum velocity of the actomyosin ATPase reaction ( Vmax ATPase) was determined using quantitative histochemistry. The effect of DNV on maximum unloaded shortening velocity ( Vo) and cross-bridge cycling rate [estimated from the rate constant for force redevelopment ( kTR) following quick release and restretch] was also examined. Two weeks after DNV, ATPiso was significantly reduced in fibers expressing MHC2X, but unaffected in fibers expressing MHCslow and MHC2A. This effect of DNV on fibers expressing MHC2X persisted even after normalization for DNV-induced reduction in MHC content. With DNV, Vo and kTR were slowed in fibers expressing MHC2X, consistent with the effect on ATPiso. The difference between Vmax ATPase and ATPiso reflects reserve capacity for ATP consumption, which was reduced across all fibers following DNV; however, this effect was most pronounced in fibers expressing MHC2X. DNV-induced reductions in ATPiso and Vmax ATPase of fibers expressing MHC2X reflect the underlying decrease in MHC content, while reduction in ATPiso also reflects a slowing of cross-bridge cycling rate.

Approximation of asymmetric flow velocity in inter-disk space of separator

10.12737/2435 ◽  
2014 ◽  
Vol 8 (4) ◽  
pp. 61-64
Author(s):  
Ибятов ◽  
Ravil Ibyatov
Keyword(s):  
Differential Equations ◽  
Flow Velocity ◽  
Centrifugal Force ◽  
Equations Of Motion ◽  
Basis Functions ◽  
Bottom Surface ◽  
Sediment Layer ◽  
Disk Space ◽  
The Asymmetry ◽  
System Of Basis Functions

We consider the motion of non-Newtonian behavior in the inter-disk space of the liquid separator. The shared medium is supplied from the periphery of the disks and moves to the center of the machine. Under the influence of centrifugal force the particles of the dispersed phase are precipitated to the bottom surface of the top disk to form a thin layer of precipitate, which moves toward the periphery of the disk. The equations of motion are solved by the equal-discharge-increments method. In this case, the flow field is introduced surfaces of equal costs for the continuous phase, which are determined by the conditions of constant flow velocity of the medium between them. To determine the locations of input surfaces, the recurrent type differential equations are recorded. The equations of motion, recorded on the flow lines, are simplified and take the form of ordinary differential equations in the longitudinal coordinate. The term, takes into account the effect of viscous friction in the equation of motion, contains the partial derivatives of the transverse coordinate. For their computation, a grid solution can be represented as a series expansion in the complete system of basis functions, satisfying the boundary condition. The presence of moving sediment layer and the centrifugal force influence causes the asymmetry of the flow in the dispersion medium in the inter-disk space. In this work the basic functions that take into account the asymmetry of the flow were constructed. In order to determine the type of basis functions, the Poiseuille flow in a conical slit with a moving wall was considered. An algebraic equation for calculating the extremum point of the function of speed made up. It is shown, that for the power fluid in the areas of increasing and decreasing functions, there are different solutions. The studies proposed a system of basis functions for the approximation of the grid solutions. It is shown, that the proposed features provide continuity of the viscous stress tensor in the whole flow area.

Sign in / Sign up

Export Citation Format

Share Document