Journal articles: 'Shear rate estimation'

1

Wu, Jie, Lachlan J. Graham, and Nabil Noui Mehidi. "Estimation of agitator flow shear rate." AIChE Journal 52, no. 7 (2006): 2323–32. http://dx.doi.org/10.1002/aic.10857.

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Forsberg, F., Z. Morvay, N. M. Rawool, C. R. Deane, and L. Needleman. "Shear rate estimation using a clinical ultrasound scanner." Journal of Ultrasound in Medicine 19, no. 5 (May 2000): 323–27. http://dx.doi.org/10.7863/jum.2000.19.5.323.

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Nitta, Naotaka, and Naoto Takeda. "Adaptive Estimation of Intravascular Shear Rate Based on Parameter Optimization." Japanese Journal of Applied Physics 47, no. 5 (May 23, 2008): 4209–14. http://dx.doi.org/10.1143/jjap.47.4209.

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Nishikawa, Masabumi. "On the estimation of average shear rate in bubble columns." Biotechnology and Bioengineering 37, no. 7 (March 25, 1991): 691–92. http://dx.doi.org/10.1002/bit.260370711.

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Kumar, Vineet, and Chandan Guria. "An improved shear rate estimation using rotating coaxial cylinder Fann viscometer." Journal of Petroleum Science and Engineering 110 (October 2013): 162–68. http://dx.doi.org/10.1016/j.petrol.2013.09.001.

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Prakash, S., and J. L. Kokini. "Estimation and prediction of shear rate distribution as a model mixer." Journal of Food Engineering 44, no. 3 (May 2000): 135–48. http://dx.doi.org/10.1016/s0260-8774(99)00166-1.

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Ngai, A. C., and H. R. Winn. "Estimation of shear and flow rates in pial arterioles during somatosensory stimulation." American Journal of Physiology-Heart and Circulatory Physiology 270, no. 5 (May 1, 1996): H1712—H1717. http://dx.doi.org/10.1152/ajpheart.1996.270.5.h1712.

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We tested the hypothesis that a shear stress-dependent mechanism is involved in the dilation of pial arterioles during somatosensory stimulation. In alpha-chloralose-anesthetized rats implanted with cranial windows, we simultaneously measured the diameter and flow velocity of pial arterioles with video and dual-slit methods. Stimulation (0.2-0.3 V, 5 Hz, 0.5 ms pulses for 20 s) of the contralateral sciatic nerve evoked consistent dilator responses in pial arterioles (36 +/- 1 micron diam) without affecting blood pressure. The dilator responses consisted of an initial transient peak dilation of 30 +/- 3%, followed by a sustained dilation of 13 +/- 1% (n = 11). Mean velocity increased by 16.4 +/- 5.7% at 5 s after stimulus onset. Wall shear rate and volume flow were calculated from diameter and velocity data by assuming a parabolic flow profile. There was no significant change in wall shear rate, whereas flow rate increased significantly during sciatic nerve stimulation. The present findings suggest that a flow (shear stress)-mediated mechanism does not play an important role in the dilator response of pial arterioles to sciatic nerve stimulation.

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Banks, H. T., Y. Wang, and D. J. Inman. "Bending and Shear Damping in Beams: Frequency Domain Estimation Techniques." Journal of Vibration and Acoustics 116, no. 2 (April 1, 1994): 188–97. http://dx.doi.org/10.1115/1.2930411.

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In this paper we consider damping mechanisms in the context of dynamic beam models. We summarize previous efforts on various damping models (strain rate or Kelvin-Voigt, time hysteresis (Boltzmann), spatial hysteresis, bending rate/square root) for the Euler-Bernoulli beam theory. The Euler-Bernoulli theory is known to be inadequate for experiments in which high frequency modes have been excited. In such cases the Timoshenko theory may be more appropriate; we consider a number of damping hypotheses for this theory. Corresponding models are proposed and compared to experimental data in the context of parameter estimation or identification problems formulated in the frequency domain. Theoretical results related to the convergence of approximations to these infinite dimensional distributed parameter system estimation problems are presented. Associated computational findings for specific beam experiments are discussed.

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Hochareon, Pramote, Keefe B. Manning, Arnold A. Fontaine, John M. Tarbell, and Steven Deutsch. "Wall Shear-Rate Estimation Within the 50cc Penn State Artificial Heart Using Particle Image Velocimetry." Journal of Biomechanical Engineering 126, no. 4 (August 1, 2004): 430–37. http://dx.doi.org/10.1115/1.1784477.

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Particle image velocimetry (PIV) has been gaining acceptance as a routine tool to evaluate the flow fields associated with fluid mechanical devices. We have developed algorithms to investigate the wall shear-rates within the 50cc Penn State artificial heart using low magnification, conventional particle image velocimetry (PIV). Wall shear has been implicated in clot formation, a major post-implant problem with artificial hearts. To address the issues of wall scattering and incomplete measurement volumes, associated with near wall measurements, we have introduced a zero masking and a fluid centroid shifting technique. Simulations using different velocity fields were conducted with the techniques to assess their viability. Subsequently, the techniques were applied to the experimental data collected. The results indicate that the size of the interrogation region should be chosen to be as small as possible to maximize resolution while large enough to ensure an adequate number of particles per region. In the current study, a 16×16 interrogation window performed well with good spatial resolution and particle density for the estimation of wall shear rate. The techniques developed with PIV allow wall shear-rate estimates to be obtained from a large number of sites at one time. Because a planar image of a flow field can be determined relatively rapidly, PIV may prove useful in any preliminary design procedure.

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Vergnes, Bruno. "Average Shear Rates in the Screw Elements of a Corotating Twin-Screw Extruder." Polymers 13, no. 2 (January 19, 2021): 304. http://dx.doi.org/10.3390/polym13020304.

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The rapid estimation of the average shear rate encountered by the material as it flows along the screw elements of a corotating twin-screw extruder is a key point for many applications. In this paper, two methods of evaluation are presented that allow the calculation of the average shear rate as a function of the screw geometry, feed rate, and screw speed. A comparison is made between the approximate and exact methods. It is shown that it is crucial to take into account the shear component due to the pressure flow, especially in the left-handed screw elements.

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Crowley, Raphael W., David Bloomquist, James R. Hayne, Courtney M. Holst, and F. D. Shah. "Estimation and Measurement of Bed Material Shear Stresses in Erosion Rate Testing Devices." Journal of Hydraulic Engineering 138, no. 11 (November 2012): 990–94. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0000608.

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Hoskins, Peter R. "Estimation of blood velocity, volumetric flow and wall shear rate using Doppler ultrasound." Ultrasound 19, no. 3 (July 6, 2011): 120–29. http://dx.doi.org/10.1258/ult.2011.011015.

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SHI, L. K., J. P. RIBA, and H. ANGELINO. "ESTIMATION OF EFFECTIVE SHEAR RATE FOR AERATED NON-NEWTONIAN LIQUIDS IN AIRLIFT BIOREACTOR”“." Chemical Engineering Communications 89, no. 1 (March 1990): 25–35. http://dx.doi.org/10.1080/00986449008940556.

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HAIDER, L., P. BERTHOLOM, C. TOURAIN, R. GUILLET, and M. BOYNARD. "S5.2. Ultrasonic estimation of red blood cell aggregation in a controlled shear rate." Biorheology 32, no. 2-3 (March 1995): 123. http://dx.doi.org/10.1016/0006-355x(95)91972-6.

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Harigaya, Yasuo, Michiyoshi Suzuki, Fujio Toda, and Masaaki Takiguchi. "Analysis of Oil Film Thickness and Heat Transfer on a Piston Ring of a Diesel Engine: Effect of Lubricant Viscosity." Journal of Engineering for Gas Turbines and Power 128, no. 3 (September 24, 2004): 685–93. http://dx.doi.org/10.1115/1.1924403.

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The effect of lubricant viscosity on the temperature and thickness of oil film on a piston ring in a diesel engine was analyzed by using unsteady state thermohydrodynamic lubrication analysis, i.e., Reynolds equation and an unsteady state two-dimensional energy equation with heat generated from viscous dissipation. The oil film viscosity was then estimated by using the mean oil film temperature and the shear rate for multigrade oils. Since the viscosity for multigrade oils is affected by both the oil film temperature and shear rate, the viscosity becomes lower as the shear rate between the ring and liner becomes higher. Under low load conditions, the viscosity decreases due to temperature rise and shear rate, while under higher load conditions, the decrease in viscosity, is attributed only to the shear rate. The oil film thickness between the ring and liner decreases with a decrease of the oil viscosity. The oil film thickness calculated by using the viscosity estimated by both the shear rate and the oil film temperature gave the smallest values. For multigrade oils, the viscosity estimation method using both the mean oil film temperature and shear rate is the most suitable one to predict the oil film thickness. Moreover, the heat transfer at ring and liner surfaces was examined.

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NAKAGAWA, Yasuyuki, Kazuo NADAOKA, Hiroshi YAGI, Yasuo NIHEI, Kouji KAWASAKI, Akihiro KIMURA, Yoji KUBOTA, and Naohiro UCHIKAWA. "BOTTOM SHEAR STRESS EVALUATION METHOD WITH STOCHASTIC APPROACH FOR ESTIMATION OF SEDIMENT TRANSPORT RATE." Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 71, no. 2 (2015): I_523—I_528. http://dx.doi.org/10.2208/kaigan.71.i_523.

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Tsou, Jean K., Jie Liu, Abdul I. Barakat, and Michael F. Insana. "Role of Ultrasonic Shear Rate Estimation Errors in Assessing Inflammatory Response and Vascular Risk." Ultrasound in Medicine & Biology 34, no. 6 (June 2008): 963–72. http://dx.doi.org/10.1016/j.ultrasmedbio.2007.11.010.

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Amangeldi, Medeu, Yanwei Wang, Asma Perveen, Dichuan Zhang, and Dongming Wei. "An Iterative Approach for the Parameter Estimation of Shear-Rate and Temperature-Dependent Rheological Models for Polymeric Liquids." Polymers 13, no. 23 (November 30, 2021): 4185. http://dx.doi.org/10.3390/polym13234185.

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Numerical flow simulations play an important role in polymer processing. One of the essential prerequisites for accurate and precise flow simulations is to obtain accurate materials functions. In the framework of the generalized Newtonian fluid model, one needs to obtain shear viscosity as a function of the rate-of-shear and temperature—as determined by rheometry—and then fitted to a mathematical model. Often, many subjectively perform the fitting without paying attention to the relative quality of the estimated parameters. This paper proposes a unique iterative algorithm for fitting the rate-of-shear and temperature-dependent viscosity model under the time–temperature superposition (TTS) principle. Proof-of-concept demonstrations are shown using the five-parameter Carreau–Yasuda model and experimental data from small-amplitude oscillatory shear (SAOS) measurements. It is shown that the newly proposed iterative algorithm leads to a more accurate representation of the experimental data compared to the traditional approach. We compare their performance in studies of the steady isothermal flow of a Carreau–Yasuda model fluid in a straight, circular tube. The two sets of parameters, one from the traditional approach and the other from the newly proposed iterative approach, show considerable differences in flow simulation. The percentage difference between the two predictions can be as large as 10% or more. Furthermore, even in cases where prior knowledge of the TTS shifting factors is not available, the newly proposed iterative approach can still yield a good fit to the experimental data, resulting in both the shifting factors and parameters for the non-Newtonian fluid model.

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Malkin, A. Ya, I. Masalova, D. Pavlovski, and P. Slatter. "Is the Choice of Flow Curve Fitting Equation Crucial for the Estimation of Pumping Characteristics?" Applied Rheology 14, no. 2 (April 1, 2004): 89–95. http://dx.doi.org/10.1515/arh-2004-0005.

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Abstract The answer to this provocative question is “no”! This is demonstrated by experiment and analysis for two very different materials – a highly concentrated emulsion and an 8%v/v Kaolin clay suspension. The flow curves of both materials clearly showed a low shear Newtonian asymptote and a pseudoplastic domain. The difference in the accuracy of the fitting equations relates mainly to the low shear rate domain. While the Cross equation is adequate over the full flow curve, the power law and the Herschel-Bulkley equations are clearly inadequate for the low shear rate range. These equations as well as the direct numerical method (using the Rabinowitsch-Weissenberg integral) were used for the calculation of the laminar pipe flow transport characteristics and the results were compared with experimental pipe flow data. It was shown that in all cases the maximum error did not exceed 5%, which is quite acceptable for engineering design, indicating that the choice of the flow curve fitting equation was unimportant.

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Bicudo, J. R., and M. F. Giorgetti. "The Effect of Strip Bed Roughness on the Reaeration Rate Coefficient." Water Science and Technology 23, no. 10-12 (May 1, 1991): 1929–39. http://dx.doi.org/10.2166/wst.1991.0649.

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Measurements are presented for the rate of atmospheric reaeration in open-channel flow under different conditions of depth and bed roughness. A 2k factorial design was employed for the estimation of both depth and bed resistance factor effects upon stream reaeration. Consistent results indicated that stream reaeration is primarily controlled by water shear, but that different modes of instability generated by a combination of depth and strip roughness levels might prevail for different boundary roughness conditions, and as a consequence, differently affect the reaeration coefficient.

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Nicosia, Mark A. "Theoretical Estimation of Shear Rate during the Oral Phase of Swallowing: Effect of Partial Slip." Journal of Texture Studies 44, no. 2 (December 16, 2012): 132–39. http://dx.doi.org/10.1111/jtxs.12005.

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Amaratunga, Maduranga, Herimonja A. Rabenjafimanantsoa, and Rune W. Time. "Estimation of shear rate change in vertically oscillating non-Newtonian fluids: Predictions on particle settling." Journal of Non-Newtonian Fluid Mechanics 277 (March 2020): 104236. http://dx.doi.org/10.1016/j.jnnfm.2020.104236.

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Al-Masry, W. A., and M. Chetty. "On the estimation of effective shear rate in external loop airlift reactors: non-Newtonian fluids." Resources, Conservation and Recycling 18, no. 1-4 (November 1996): 11–24. http://dx.doi.org/10.1016/s0921-3449(96)01164-0.

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Testut, L., I. E. Tabacco, C. Bianchi, and F. Rémy. "Influence of geometrical boundary conditions on the estimation of rheological parameters." Annals of Glaciology 30 (2000): 102–6. http://dx.doi.org/10.3189/172756400781820877.

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AbstractImproved knowledge of geometrical boundary conditions, such as bedrock geometry and surface topography, can contribute significantly to glaciological studies including ice-sheet-flow modelling. Precise thickness and altimetric data allow an estimation of ice-flow direction, the balance velocity and the basal shear stress. These parameters are calculated along a 1160 km profile in East Antarctica using a relationship between shear stress, basal temperature, the Glen flow exponent and a parameter related to strain rate. Strong variations of the flow-law parameters and basal conditions are found to play a major role in the ice-flow pattern. Sliding, anisotropy and longitudinal stress strongly perturb the validity of the law, but their signature can be identified.

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ALANAZI, AHMED BAKHIT, MOHAMED YACIN SIKKANDAR, and MOHAMED IBRAHIM WALY. "ESTIMATION OF WALL SHEAR STRESS OF COMPLIANT THORACIC AORTA WITH ANEURYSM." Journal of Mechanics in Medicine and Biology 20, no. 03 (April 2020): 2050013. http://dx.doi.org/10.1142/s021951942050013x.

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In this paper, a numerical estimation of wall shear stress (WSS) in a compliant Thoracic Aorta (TA) with aneurysm is modeled and the hemodynamic pattern is studied using Computational Fluid Dynamics (CFD). Thoracic Aortic Aneurysm (TAA) is an excessively localized enlargement of TA caused by weakness in the arterial wall and it can rupture the inner wall intima and continue on to the outer wall adventitia. WSS is a tangential force exerted by blood flow on the vessel wall, and its estimation is clinically very important because any change in WSS is considered as a vital cue in the onset of aneurysm. In this work, a three-dimensional (3D) model of a TAA reconstructed from computed tomography (CT) images comprising of 600 slices with 1-mm resolution from neck to hip is considered and patient-specific simulations have been carried out in compliant TA under rest and exercise conditions. The findings show that the change in wall geometry was marginal due to variation in pressure forces inside and is not the primary source for expansion of an aneurysm. It was inferred that expansion was rather due to thinning of the wall, owing to damage caused to the inner lining of the tissues, at regions of high WSS. It was found that the geometry extraction is important as any change in length causes a corresponding variation in mass flow through it. Although mass conservation is maintained irrespective of the length, it does affect the rate of flow due to shifting in the pressure boundary conditions with the length as it varies the pressure inside the system. Modeling of the geometry is very important as the change in mass flow will affect the outlet velocity and strength of vortices. Surprisingly, the split-up of flow is consistent but the geometric change in the model has no effect on WSS values and flow pattern. The results of this study provide important information such as blood flow pattern and pressure drops in the compliant TA on WSS estimations with TAA diseases.

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Wang, Wen. "Change in Properties of the Glycocalyx Affects the Shear Rate and Stress Distribution on Endothelial Cells." Journal of Biomechanical Engineering 129, no. 3 (November 4, 2006): 324–29. http://dx.doi.org/10.1115/1.2720909.

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The endothelial glycocalyx mediates interactions between the blood flow and the endothelium. This study aims to evaluate, quantitatively, effects of structural change of the glycocalyx on stress distribution and shear rate on endothelial cells. In the study, the endothelial glycocalyx is modeled as a surface layer of fiber matrix and when exposed to laminar shear flow, the matrix deforms. Fluid velocity and stress distribution inside the matrix and on cell membranes are studied based on a binary mixture theory. Parameters, such as the height and porosity of the matrix and the drag coefficient between fluid and matrix fibrils, are based on available data and estimation from experiments. Simple theoretical solutions are achieved for fluid velocity and stress distribution in the surface matrix. Degradation of the matrix, e.g., by enzyme digestion, is represented by reductions in the volume fraction of fibrils, height, and drag coefficient. From a force balance, total stress on endothelial surface remains constant regardless of structural alteration of the glycocalyx. However, the stress that is transmitted to endothelial cells by direct “pulling” of fiber branches of the glycocalyx is reduced significantly. Fluid shear rate at the cell membrane, on the other hand, increases. The study gives quantitative insight into the effect of the structural change of the glycocalyx on the shear rate and pulling stress on the endothelium. Results can be used to interpret experiments on effects of the glycocalyx in shear induced endothelial responses.

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Carew, E. O., E. A. Talman, D. R. Boughner, and I. Vesely. "Quasi-Linear Viscoelastic Theory Applied to Internal Shearing of Porcine Aortic Valve Leaflets." Journal of Biomechanical Engineering 121, no. 4 (August 1, 1999): 386–92. http://dx.doi.org/10.1115/1.2798335.

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The elements of Quasi-Linear Viscoelastic (QLV) theory have been applied to model the internal shear mechanics of fresh and glutaraldehyde-fixed porcine aortic valve leaflets. A novel function estimation method was used to extract the material functions from experimental shear data obtained at one strain rate, and the model was used to predict the material response at different strain rates. In general, experiments and predictions were in good agreement, the larger discrepancies being in the prediction of peak stresses and hysteresis in cyclic shear. In shear, fixed tissues are stiffer (mean initial shear modulus, 13 kPa versus 427 Pa), take longer to relax to steady state (mean τ2 4,736 s versus 1,764 s) with a slower initial relaxation rate (mean magnitude of G˙(0), 1 s−1 versus 5 s−1), and relax to a lesser extent than fresh tissues (mean percentage stress remaining after relaxation, 60 versus 45 percent). All differences were significant at p = 0.04 or less, except for the initial relaxation slope. We conclude that shear experiments can complement traditional tensile and biaxial experiments toward providing a complete mechanical description of soft biomaterials, particularly when evaluating alternative chemical fixation techniques.

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Fatemi, Ray S., and Stanley E. Rittgers. "Derivation of Shear Rates From Near-Wall LDA Measurements Under Steady and Pulsatile Flow Conditions." Journal of Biomechanical Engineering 116, no. 3 (August 1, 1994): 361–68. http://dx.doi.org/10.1115/1.2895743.

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Atherosclerosis, thrombosis, and intimal hyperplasia are major forms of cardiovascular diseases in the United States. Previous studies indicate a significant correlation between hemodynamics, in particular, wall shear rate, and pathology of the arterial walls. While results of these studies implicate morphologic and functional changes related to wall shear rate magnitude, a standard technique for wall shear rate measurement has not been established. In this study, theoretical and in-vitro experimental fully developed steady and physiologic pulsatile flow waveforms have been used to obtain velocity profiles in the near-wall region. The estimated wall shear rates from these results are compared to the theoretical value to assess the accuracy of the approximating technique. Experimentally obtained results from LDA suggest that in order to minimize the error in velocity data, and subsequently, the wall shear rate, the first measured velocity has to be 500 μm away from the wall. While a linear approximation did not produce errors larger than 16.4 percent at peak systole, these errors substantially increased as the velocity magnitudes decreased during late systole and diastole. Overall, a third degree polynomial curve fit using four points produced the most accurate estimation of wall shear rate through out the cardiac cycle. Results of higher degree curve-fitting functions can be unpredictable due to potential oscillations of the function near the wall. Hence, based on the results of this study, use of a linear approximation is not recommended; a third degree curve-fitting polynomial, using four points provided the most accurate approximation for these flow waveforms.

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Sisodia, Mahiraj Singh, Dilip Kumar Rajak, Akhilendra Kumar Pathak, and Chandan Guria. "An improved estimation of shear rate for yield stress fluids using rotating concentric cylinder Fann viscometer." Journal of Petroleum Science and Engineering 125 (January 2015): 247–55. http://dx.doi.org/10.1016/j.petrol.2014.11.027.

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YADAV, Abhishek, Suresh KANNAUJIYA, Prashant Kumar CHAMPATI RAY, Rajeev Kumar YADAV, and Param Kirti GAUTAM. "Estimation of crustal deformation parameters and strain build-up in Northwest Himalaya using GNSS data measurements." Contributions to Geophysics and Geodesy 51, no. 3 (September 28, 2021): 225–43. http://dx.doi.org/10.31577/congeo.2021.51.3.2.

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GPS measurements have proved extremely useful in quantifying strain accumulation rate and assessing seismic hazard in a region. Continuous GPS measurements provide estimates of secular motion used to understand the earthquake and other geodynamic processes. GNSS stations extending from the South of India to the Higher Himalayan region have been used to quantify the strain build-up rate in Central India and the Himalayan region to assess the seismic hazard potential in this realm. Velocity solution has been determined after the application of Markov noise estimated from GPS time series data. The recorded GPS data are processed along with the closest International GNSS stations data for estimation of daily basis precise positioning. The baseline method has been used for the estimation of the linear strain rate between the two stations. Whereas the principal strain axes, maximum shear strain, rotation rate, and crustal shortening rate has been calculated through the site velocity using an independent approach; least-square inversion approach-based triangulation method. The strain rate analysis estimated by the triangulation approach exhibits a mean value of extension rate of 26.08 nano-strain/yr towards N131°, the compression rate of –25.38 nano-strain/yr towards N41°, maximum shear strain rate of 51.47 nano-strain/yr, dilation of –37.57 nano-strain/yr and rotation rate of 0.7°/Ma towards anti-clockwise. The computed strain rate from the Baseline method and the Triangulation method reports an extensive compression rate that gradually increases from the Indo-Gangetic Plain in South to Higher Himalaya in North. The slip deficit rate between India and Eurasia Plate in Kumaun Garhwal Himalaya has been computed as 18±1.5 mm/yr based on elastic dislocation theory. Thus, in this study, present-day surface deformation rate and interseismic strain accumulation rate in the Himalayan region and the Central Indian region have been estimated for seismic hazard analysis using continuous GPS measurements.

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Rodgers, Michael, Michael McVay, David Horhota, Jon Sinnreich, and Jose Hernando. "Assessment of shear strength from measuring while drilling shafts in Florida limestone." Canadian Geotechnical Journal 56, no. 5 (May 2019): 662–74. http://dx.doi.org/10.1139/cgj-2017-0629.

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The focus of this research is the real-time assessment of drilled shaft capacity based on the unconfined compressive strength (qu) obtained from measuring while drilling (MWD). Measures of qu, a function of rock strength commonly used in drilled shaft design, are provided through five monitored drilling parameters: torque, crowd, rotational speed, penetration rate, and bit diameter. Monitored shaft installations took place at three separate locations on drilled shafts, which were subsequently load tested. Using the qu values obtained from MWD, side shear was estimated in portions of each shaft where instrumented segments indicated the side shear was fully mobilized for direct comparison. To consider all of the current side shear equations used in Florida drilled shaft design, the estimation of tensile strength (qt) in real time was also needed. This led to a theoretical approach to establish the qt/qu relationship that was later verified empirically and provided new correlations between material and mechanical properties of Florida geomaterials. A comparative analysis indicated that the results from multiple established side shear equations, used with qu from MWD, align well with the results obtained from load testing. This suggests that estimating drilled shaft capacity from MWD is viable to reduce spatial uncertainty.

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Chen, Zheng-long, Yuan-lin Song, Zhao-yan Hu, Su Zhang, and Ya-zhu Chen. "An estimation of mechanical stress on alveolar walls during repetitive alveolar reopening and closure." Journal of Applied Physiology 119, no. 3 (August 1, 2015): 190–201. http://dx.doi.org/10.1152/japplphysiol.00112.2015.

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Alveolar overdistension and mechanical stresses generated by repetitive opening and closing of small airways and alveoli have been widely recognized as two primary mechanistic factors that may contribute to the development of ventilator-induced lung injury. A long-duration exposure of alveolar epithelial cells to even small, shear stresses could lead to the changes in cytoskeleton and the production of inflammatory mediators. In this paper, we have made an attempt to estimate in situ the magnitudes of mechanical stresses exerted on the alveolar walls during repetitive alveolar reopening by using a tape-peeling model of McEwan and Taylor (35). To this end, we first speculate the possible ranges of capillary number ( Ca) ≡ μU/ γ (a dimensionless combination of surface tension γ, fluid viscosity μ, and alveolar opening velocity U) during in vivo alveolar opening. Subsequent calculations show that increasing respiratory rate or inflation rate serves to increase the values of mechanical stresses. For a normal lung, the predicted maximum shear stresses are <15 dyn/cm2 at all respiratory rates, whereas for a lung with elevated surface tension or viscosity, the maximum shear stress will notably increase, even at a slow respiratory rate. Similarly, the increased pressure gradients in the case of elevated surface or viscosity may lead to a pressure drop >300 dyn/cm2 across a cell, possibly inducing epithelial hydraulic cracks. In addition, we have conceived of a geometrical model of alveolar opening to make a prediction of the positive end-expiratory pressure (PEEP) required to splint open a collapsed alveolus, which as shown by our results, covers a wide range of pressures, from several centimeters to dozens of centimeters of water, strongly depending on the underlying pulmonary conditions. The establishment of adequate regional ventilation-to-perfusion ratios may prevent recruited alveoli from reabsorption atelectasis and accordingly, reduce the required levels of PEEP. The present study and several recent animal experiments likewise suggest that a lung-protective ventilation strategy should not only include small tidal volume and plateau pressure limitations but also consider such cofactors as ventilation frequency and inflation rate.

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Goto, Yasutaka, Ichiro Yasuda, and Maki Nagasawa. "Turbulence Estimation Using Fast-Response Thermistors Attached to a Free-Fall Vertical Microstructure Profiler." Journal of Atmospheric and Oceanic Technology 33, no. 10 (October 2016): 2065–78. http://dx.doi.org/10.1175/jtech-d-15-0220.1.

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AbstractEstimation of turbulence intensity with a fast-response thermistor is examined by comparing the energy dissipation rate from a Fastip Probe, model 07 (FP07), thermistor with from a shear probe, both of which are attached to a free-fall microstructure profiler with the fall rate of 0.6–0.7 m s−1. Temperature gradient spectra corrected with previously introduced frequency response functions represented by a single-pole low-pass filter yields with a bias that strongly depends on turbulence intensity. Meanwhile, the correction with the form of a double-pole low-pass filter derives less bias than of single-pole low-pass filter. The rate is compatible with when the double-pole correction with the time constant of 3 × 10−3 s is applied, and 68% of data are within a factor of 2.8 of in the wide range of = 10−10–3 × 10−7 W kg−1. The rate is still compatible with even in the anisotropy range, where the buoyancy Reynolds number is 20–100. Turbulence estimation from the fast-response thermistor is thus confirmed to be valid in this range by applying the appropriate correction to temperature gradient spectra. Measurements with fast-response thermistors, which have not been common because of their poor frequency response, are less sensitive to the vibration of profilers than those with shear probes. Hence, measurements could be available when a fast-response thermistor is attached to a CTD frame or a float, which extends the possibility of obtaining much more turbulence data in deep and wide oceans.

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Li, Chunlei, Long Yu, Xianjing Kong, and Heyue Zhang. "Estimation of undrained shear strength in rate-dependent and strain-softening surficial marine clay using ball penetrometer." Computers and Geotechnics 153 (January 2023): 105084. http://dx.doi.org/10.1016/j.compgeo.2022.105084.

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Udawattha, Dilan S., Pabasara Embuldeniya, and Mahinsasa Narayana. "On the Estimation of Viscosities of Non-Newtonian Nanofluids: A Reliable Approach Based on the Shear Rate." Journal of Nanofluids 8, no. 4 (April 1, 2019): 861–69. http://dx.doi.org/10.1166/jon.2019.1636.

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Qin, Xulong, Tong Yang, Zheng-an Yao, and Wenshu Zhou. "Vanishing shear viscosity limit and boundary layer study for the planar MHD system." Mathematical Models and Methods in Applied Sciences 29, no. 06 (June 15, 2019): 1139–74. http://dx.doi.org/10.1142/s0218202519500180.

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We consider an initial boundary problem for the planar MHD system under the general condition on the heat conductivity coefficient that depends on both the temperature and the density. Firstly, the global existence of strong solution for large initial data is obtained, and then the limit of the vanishing shear viscosity is justified. In addition, the [Formula: see text] convergence rate is obtained together with the estimation on the thickness of the boundary layer.

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McClure, Mark W., and Roland N. Horne. "Investigation of injection-induced seismicity using a coupled fluid flow and rate/state friction model." GEOPHYSICS 76, no. 6 (November 2011): WC181—WC198. http://dx.doi.org/10.1190/geo2011-0064.1.

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We describe a numerical investigation of seismicity induced by injection into a single isolated fracture. Injection into a single isolated fracture is a simple analog for shear stimulation in enhanced geothermal systems (EGS) during which water is injected into fractured, low permeability rock, triggering slip on preexisting large scale fracture zones. A model was developed and used that couples (1) fluid flow, (2) rate and state friction, and (3) mechanical stress interaction between fracture elements. Based on the results of this model, we propose a mechanism to describe the process by which the stimulated region grows during shear stimulation, which we refer to as the sequential stimulation (SS) mechanism. If the SS mechanism is realistic, it would undermine assumptions that are made for the estimation of the minimum principal stress and unstimulated hydraulic diffusivity. We investigated the effect of injection pressure on induced seismicity. For injection at constant pressure, there was not a significant dependence of maximum event magnitude on injection pressure, but there were more relatively large events for higher injection pressure. Decreasing injection pressure over time significantly reduced the maximum event magnitude. Significant seismicity occurred after shut-in, which was consistent with observations from EGS stimulations. Production of fluid from the well immediately after injection inhibited shut-in seismic events. The results of the model in this study were found to be broadly consistent with results from prior work using a simpler treatment of friction that we refer to as static/dynamic. We investigated the effect of shear-induced pore volume dilation and the rate and state characteristic length scale, [Formula: see text]. Shear-induced pore dilation resulted in a larger number of lower magnitude events. A larger value of [Formula: see text] caused slip to occur aseismically.

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Pellicer, J., J. Delegido, J. Dolz, M. Dolz, M. J. Hernández, and M. Herráez. "Influence of shear rate and concentration ratio on viscous synergism. Application to xanthan—Iocust bean gum— NaCMC mixtures Influencia de la velocidad de cizalla y la relación de concentraciones en la sinergia viscosa. Aplicación a mezclas de xantana-garrofín-CMCNa." Food Science and Technology International 6, no. 5 (October 2000): 415–23. http://dx.doi.org/10.1177/108201320000600508.

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A method is described that allows the development of an empirical approach to quantify synergistic interactions and their variations with shear rate. The approach is based on the definition of a viscous synergism index, Iv. The method is applied to xanthan-locust bean gum gels, and an equation is developed for relating the synergism index to shear rate, γ, and the locust bean gum/xanthan gum concentration ratio, z. The value of at which that function has a maximum, IMV, is calculated. This value of z provided an estimation of the proportion of gums at which maximum synergism occurs. A decreasing exponential dependence of these IMV on γ is shown. The influence of the addition of a fixed proportion of a third gum (NaCMC) is also analyzed. The results obtained for the higher γ values are analogous to those of other authors.

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Wan, Jinjin, Fangli He, Yongfeng Zhao, Hongmei Zhang, Xiaodong Zhou, and Mingxi Wan. "Non-invasive Vascular Radial/Circumferential Strain Imaging and Wall Shear Rate Estimation Using Video Images of Diagnostic Ultrasound." Ultrasound in Medicine & Biology 40, no. 3 (March 2014): 622–36. http://dx.doi.org/10.1016/j.ultrasmedbio.2013.10.007.

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Ookawara, Shinichi, Akihisa Yano, Kohei Ogawa, and Koichi Taniguchi. "Estimation of Red Cell Deformability Based on Flow Curve of Whole Blood in the Higher Shear Rate Range." KAGAKU KOGAKU RONBUNSHU 27, no. 2 (2001): 228–35. http://dx.doi.org/10.1252/kakoronbunshu.27.228.

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Zeng, Zhihua, Yuqing Wang, and Chun-Chieh Wu. "Environmental Dynamical Control of Tropical Cyclone Intensity—An Observational Study." Monthly Weather Review 135, no. 1 (January 1, 2007): 38–59. http://dx.doi.org/10.1175/mwr3278.1.

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Abstract The effects of two environmental dynamical factors, namely, the transitional speed and vertical wind shear, on tropical cyclone (TC) intensification, intensity, and lifetime peak intensity were analyzed based on observations in the western North Pacific during 1981–2003. In general, both the fast translation and strong vertical shear are negative to both TC intensification and the lifetime peak intensity. Both the very intense TCs and the TCs with rapid intensification rate are found only to occur in a narrow range of translational speeds between 3 and 8 m s−1, and in relatively weak vertical shear. The overwhelming majority of western North Pacific TCs reach their lifetime peak intensity just prior to recurvature where their environmental steering flow and vertical shear are both weak. The results show that few TCs intensified when they moved faster than 15 m s−1, or when their large-scale environmental vertical shear is larger than 20 m s−1. The intensification rate of TCs is found to increase with decreasing vertical shear while the majority of the weakening storms experience relatively strong vertical shear. Overall, strong vertical shear prohibits rapid intensification and most likely results in the weakening of TCs, similar to the fast storm translation. Based on the statistical analysis, a new empirical maximum potential intensity (MPI) has been developed, which includes the combined negative effect of translational speed and vertical shear as the environmental dynamical control in addition to the positive contribution of SST and the outflow temperature as the thermodynamic control. The new empirical MPI can not only provide more accurate estimation of TC maximum intensity but also better explain the observed behavior of the TC maximum intensity and help explain the thermodynamic and environmental dynamical controls of TC intensity. Implications of the new empirical MPI are discussed.

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Aizawa, Kunihiko, Sara Sbragi, Alessandro Ramalli, Piero Tortoli, Francesco Casanova, Carmela Morizzo, Clare E. Thorn, Angela C. Shore, Phillip E. Gates, and Carlo Palombo. "Brachial artery vasodilatory response and wall shear rate determined by multigate Doppler in a healthy young cohort." Journal of Applied Physiology 124, no. 1 (January 1, 2018): 150–59. http://dx.doi.org/10.1152/japplphysiol.00310.2017.

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Wall shear rate (WSR) is an important stimulus for the brachial artery flow-mediated dilation (FMD) response. However, WSR estimation near the arterial wall by conventional Doppler is inherently difficult. To overcome this limitation, we utilized multigate Doppler to accurately determine the WSR stimulus near the vessel wall simultaneously with the FMD response using an integrated FMD system [Ultrasound Advanced Open Platform (ULA-OP)]. Using the system, we aimed to perform a detailed analysis of WSR-FMD response and establish novel WSR parameters in a healthy young population. Data from 33 young healthy individuals (27.5 ± 4.9 yr, 19 females) were analyzed. FMD was assessed with reactive hyperemia using ULA-OP. All acquired raw data were postprocessed using custom-designed software to obtain WSR and diameter parameters. The acquired velocity data revealed that nonparabolic flow profiles within the cardiac cycle and under different flow states, with heterogeneity between participants. We also identified seven WSR magnitude and four WSR time-course parameters. Among them, WSR area under the curve until its return to baseline was the strongest predictor of the absolute ( R2 = 0.25) and percent ( R2 = 0.31) diameter changes in response to reactive hyperemia. For the first time, we identified mono- and biphasic WSR stimulus patterns within our cohort that produced different magnitudes of FMD response [absolute diameter change: 0.24 ± 0.10 mm (monophasic) vs. 0.17 ± 0.09 mm (biphasic), P < 0.05]. We concluded that accurate and detailed measurement of the WSR stimulus is important to comprehensively understand the FMD response and that this advance in current FMD technology could be important to better understand vascular physiology and pathology. NEW & NOTEWORTHY An estimation of wall shear rate (WSR) near the arterial wall by conventional Doppler ultrasound is inherently difficult. Using a recently developed integrated flow-mediated dilation ultrasound system, we were able to accurately estimate WSR near the wall and identified a number of novel WSR variables that may prove to be useful in the measurement of endothelial function, an important biomarker of vascular physiology and disease.

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Ching, Jianye, and Kok-Kwang Phoon. "Multivariate distribution for undrained shear strengths under various test procedures." Canadian Geotechnical Journal 50, no. 9 (September 2013): 907–23. http://dx.doi.org/10.1139/cgj-2013-0002.

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The undrained shear strength (su) of a clay is not a constant. In particular, su values of a clay evaluated by different test procedures are different because these tests may have different stress states, stress histories, degrees of sampling disturbance, and strain rates. This study constructs the multivariate probability distribution of su from various test procedures based on a large clay database. This multivariate distribution provides an estimation of the normalized undrained shear strength based on four factors: test mode, overconsolidation ratio, strain rate, and plasticity. Once this multivariate distribution is constructed, interesting questions can be answered systematically using simple Bayesian analysis, e.g., given the su value for one test procedure, what is the updated mean and coefficient of variation of the su value for another test procedure?

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Mohamed, Ibrahim O., and Eihab Hassan. "Time-Dependent and Time-Independent Rheological Characterization of Date Syrup." Journal of Food Research 5, no. 2 (March 7, 2016): 13. http://dx.doi.org/10.5539/jfr.v5n2p13.

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The time-dependent and time-independent rheological properties of Barhi date syrup have been investigated. Rheological measurements were performed with a rotational viscometer with parallel plate geometry. The date syrup showed thixotropic behavior and a first order exponential decay model characterized the time-dependent behavior. The rate constant of the structure breakdown was found to be a function of shear rate. The steady shear flow measurements showed that the date syrup is a non-Newtonian material fit the power law model (p <0.001). The Arrhenius model described the effect of temperature on consistency coefficient; the estimated parameters from the Arrhenius equation were used to develop a prediction rheological model for the apparent viscosity. The model accurately predicts the experimental data even when extrapolating beyond parameter estimation temperature range. The time-independent viscosity model was satisfactory for modeling date syrup despite the presence of thixotropic behavior.

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Zhang, L. L., Delwyn G. Fredlund, Murray D. Fredlund, and G. Ward Wilson. "Modeling the unsaturated soil zone in slope stability analysis." Canadian Geotechnical Journal 51, no. 12 (December 2014): 1384–98. http://dx.doi.org/10.1139/cgj-2013-0394.

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The linear form of the extended Mohr–Coulomb shear strength equation uses a [Formula: see text] parameter to quantify the rate of increase in shear strength relative to matric suction. When the [Formula: see text] value is unknown, a [Formula: see text] equal to 15° is sometimes used in the slope stability study to assess the influence of matric suction on the stability of a slope. In many cases, however, a [Formula: see text] value of zero is used, signifying that the effect of matric suction is ignored. Experiment results have shown that the relationship between the shear strength of an unsaturated soil and matric suction is nonlinear. Several semi-empirical estimation equations have been proposed relating the unsaturated shear strength to the soil-water characteristic curve. In this paper, the results of a study using two-dimensional slope stability analysis along with an estimated nonlinear shear strength equations is presented. The effects of using an estimated nonlinear shear strength equation for the unsaturated soils are illustrated using three example problems. Several recommendations are made for engineering practice based on the results of the example problems. If the air-entry value (AEV) of a soil is smaller than 1 kPa, the effect of matric suction on the calculated factor of safety is trivial and the [Formula: see text] value can be assumed to be zero. If the AEV of a soil is between 1 and 20 kPa, the nonlinear equations of unsaturated shear strength should be adopted. For soils with an AEV value between 20 and 200 kPa, an assumed [Formula: see text] value of 15° provides a reasonable estimation of the effects of unsaturated shear strength in most cases. For soils with an AEV greater than 200 kPa, [Formula: see text] can generally be assumed to be equal to the effective angle of internal friction, [Formula: see text], in applications where geotechnical structures have matric suctions around 100 kPa.

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Lee, Junhwan, Rodrigo Salgado, and J. Antonio H. Carraro. "Stiffness degradation and shear strength of silty sands." Canadian Geotechnical Journal 41, no. 5 (September 1, 2004): 831–43. http://dx.doi.org/10.1139/t04-034.

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Soils behave nonlinearly from very early loading stages. When granular soils contain a certain amount of fines, the degree of nonlinearity also changes, as stiffness and strength characteristics vary with fines content. Hyperbolic stressstrain models and variations of these models are often used for description of the nonlinear behavior. A modified hyperbolic stressstrain relationship is used in this paper for representing the degradation of the elastic modulus of silty sands. The model is based on two modulus degradation parameters that determine the magnitude and rate of modulus degradation as a function of stress level. Realistic representation of soil behavior using this nonlinear relationship requires estimation of the degradation parameters as a function of silt content and relative density DR. A series of triaxial test results on sands containing different amounts of nonplastic silt were analyzed with this purpose. Relationships between the degradation parameters and cone penetration test (CPT) cone resistance qc are also proposed.Key words: hyperbolic model, silty sands, triaxial tests, modulus degradation, stressstrain response, shear strength, Gmax.

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Lenkovskiy, T. M., V. V. Kulyk, Z. A. Duriagina, R. A. Kovalchuk, V. H. Topilnytskyy, V. V. Vira, and T. L. Tepla. "Mode I and mode II fatigue crack growth resistance characteristics of high tempered 65G steel." Archives of Materials Science and Engineering 1, no. 84 (March 1, 2017): 34–41. http://dx.doi.org/10.5604/01.3001.0010.3029.

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Purpose: To investigate the fatigue crack growth at normal tension and transverse shear of 65G steel with the high tempered martensite microstructure and to build an appropriate fatigue crack growth rate curves. To determine the main and auxiliary fatigue crack growth resistance characteristics, which are necessary for machine parts life-time estimation at rolling contact fatigue conditions. Design/methodology/approach: For determination of fatigue crack growth resistance at normal tension a standard compact specimens with edge crack were tested using a hydraulic testing machine and fatigue testing at transverse shear were performed on the I-beam specimens with the edge longitudinal crack using the original testing setup. For crack growth measurement an optical cathetometer B-630 was used. The crack growth rate V was calculated as crack length increment during loading cycles. The stress intensity factor range K was determined by dependence "K = (1 – R)Kmax accordingly to the standard test methods. To establish crack faces friction factor at transverse shear fragments of fractured beam specimen containing crack faces were cut out and tested as a friction pair according to Amontons Coulomb's law. On the base of test results the fatigue crack growth rate curves in logarithmic coordinates "K vs. V were built. These graphical dependencies for normal tension and transverse shear were used for determination of fatigue crack growth resistance characteristics: fatigue threshold "Kth, fracture toughness "Kfc, "K1-2 and "K2-3 which indicates the beginning and the end of middle-amplitude region of curve, "K*, parameters C and n of Paris’s equation. Metallographic and fractographic analyses were performed on the scanning electronic microscope Zeiss EVO 40XVP. Findings: Empirical dependences of the stress intensity factor range on fatigue crack growth rate at normal tension and transverse shear of 65G steel with the high tempered martensite microstructure are obtained. Based on these graphical dependencies the fatigue thresholds and fracture toughness as well as the parameters of Paris’s equation are determined. Research limitations/implications: The fatigue crack growth on 65G steel under low-, medium- and high-amplitude cyclic loading at normal tension and transverse shear was investigated. The fatigue crack growth rate values for a wide range of stress intensity factor are estimated. On the base of fractographical analysis the features of fracture of high tempered martensite in 65G steel at transverse shear are studied. It is shown that the transverse shear crack faces friction factor for high tempered martensite structure is less than for low tempered martensite. Practical implications: Using the fatigue crack growth resistance characteristics of 65G steel at normal tension and transverse shear and related fatigue crack growth rate curves it is possible to predict the life-time of machine parts made of steels with high tempered martensite structure, working at rolling contact fatigue conditions. Originality/value: Complete fatigue crack growth rate curves of 65G steel with tempered martensite structure at normal tension and transverse shear are built and the fatigue crack growth resistance characteristics for both modes of fracture are determined for the first time.

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Watanabe, Tohru. "A Model-Based Approach to Adaptive Control Optimization in Milling." Journal of Dynamic Systems, Measurement, and Control 108, no. 1 (March 1, 1986): 56–64. http://dx.doi.org/10.1115/1.3143743.

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An adaptive control optimization system using a model to represent actual physical phenomena in milling is discussed. The model is used for the identification of physical parameters, the calculation of the temperature at the tool edges, and the estimation of the tool wear rate. The shear angle of the shear plane, the flank wear land length of the tool edge, the true contact area at the flank wear land, the radial depth and the axial depth of cut are identified as the physical parameters, the shear stress, and the hardness of the work material from bending moments and torque in the spindle generated by the cutting force. The temperature at the flank wear land is calculated from identified parameters. The tool wear is represented theoretically as the summation of the thermal, mechanical and shock wears. Each wear is calculated from identified parameters and the temperature at the tool edges. Adaptive control experiments to keep the tool-wear rate at a constant value verify that the total system works well. An adaptive control optimization system using the tool-wear rate equation is compared with an adaptive control constraint system using Taylor’s tool life equation in a computer simulation. The simulation shows that adaptive control optimization gives higher cost efficiency than adaptive control constraint when the process parameters vary.

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SHI, Weiwei, Masaaki TAMAGAWA, Yingming YI, and Takanori YOSHIKAWA. "S0220201 Estimation of thrombus formation by high shear rate on various flows using both thrombus visualization and CFD Analysis." Proceedings of Mechanical Engineering Congress, Japan 2015 (2015): _S0220201——_S0220201—. http://dx.doi.org/10.1299/jsmemecj.2015._s0220201-.

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Kawaguchi, Fukui, Funamoto, Tanaka, Tanaka, Murata, Miyauchi, and Hayase. "Viscosity Estimation of a Suspension with Rigid Spheres in Circular Microchannels Using Particle Tracking Velocimetry." Micromachines 10, no. 10 (October 4, 2019): 675. http://dx.doi.org/10.3390/mi10100675.

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Suspension flows are ubiquitous in industry and nature. Therefore, it is important to understand the rheological properties of a suspension. The key to understanding the mechanism of suspension rheology is considering changes in its microstructure. It is difficult to evaluate the influence of change in the microstructure on the rheological properties affected by the macroscopic flow field for non-colloidal particles. In this study, we propose a new method to evaluate the changes in both the microstructure and rheological properties of a suspension using particle tracking velocimetry (PTV) and a power-law fluid model. Dilute suspension (0.38%) flows with fluorescent particles in a microchannel with a circular cross section were measured under low Reynolds number conditions (Re ≈ 10−4). Furthermore, the distribution of suspended particles in the radial direction was obtained from the measured images. Based on the power-law index and dependence of relative viscosity on the shear rate, we observed that the non-Newtonian properties of the suspension showed shear-thinning. This method will be useful in revealing the relationship between microstructural changes in a suspension and its rheology.

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Journal articles on the topic 'Shear rate estimation'

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