Journal articles: 'Hydraulic activation'

1

Bao, Xuewei, and David W. Eaton. "Fault activation by hydraulic fracturing in western Canada." Science 354, no. 6318 (November 17, 2016): 1406–9. http://dx.doi.org/10.1126/science.aag2583.

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Newton, Christopher R., Brian Curran, and Gregory P. Victorino. "Angiotensin II type 1 receptor activation increases microvascular hydraulic permeability." Surgery 136, no. 5 (November 2004): 1054–60. http://dx.doi.org/10.1016/j.surg.2004.04.031.

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Toner, M., E. G. Cravalho, and M. D. Cosman. "The hydraulic conductivity and the activation energy of bovine embryos." Cryobiology 23, no. 6 (December 1986): 548–49. http://dx.doi.org/10.1016/0011-2240(86)90078-7.

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Luke, Adam, Brad Kaplan, Jeff Neal, Jeremiah Lant, Brett Sanders, Paul Bates, and Doug Alsdorf. "Hydraulic modeling of the 2011 New Madrid Floodway activation: a case study on floodway activation controls." Natural Hazards 77, no. 3 (March 8, 2015): 1863–87. http://dx.doi.org/10.1007/s11069-015-1680-3.

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Eyre, Thomas S., David W. Eaton, Megan Zecevic, David D’Amico, and Danylo Kolos. "Microseismicity reveals fault activation before Mw 4.1 hydraulic-fracturing induced earthquake." Geophysical Journal International 218, no. 1 (April 8, 2019): 534–46. http://dx.doi.org/10.1093/gji/ggz168.

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Aggarwal, Shanti J., Kenneth R. Diller, and Charles R. Baxter. "Hydraulic permeability and activation energy of human keratinocytes at subzero temperatures." Cryobiology 25, no. 3 (June 1988): 203–11. http://dx.doi.org/10.1016/0011-2240(88)90027-2.

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7

Gong, Chen Chen, Xiao Bo Yan, De Li Lou, and Dong Xu Li. "Influence on Activation Property of Coal Gangue by Calcining Temperature." Applied Mechanics and Materials 174-177 (May 2012): 1137–40. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.1137.

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Influence on activation property of coal gangue by calcining temperature was discussed. The experimental results show that C12A7 and C2S with hydraulic-activity are created in coal gangue calcined at 900 - 950°C which has reasonable pore distribution after hydrating.

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Lopez, Jennifer Contreras, Lothar Lauterböck, and Birgit Glasmacher. "Determination of the membrane hydraulic permeability of MSCs." Current Directions in Biomedical Engineering 2, no. 1 (September 1, 2016): 323–27. http://dx.doi.org/10.1515/cdbme-2016-0072.

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AbstractA successful cryopreservation is based on knowledge of the optimal cooling rate. So far, this is often determined by way of complex parameter studies. Alternatively, the identification of cell specific characteristics, such as osmotic behaviour, membrane hydraulic permeability and activation energy could be used to calculate the optimal cooling rate. These parameters should be determined for supra-zero and sub-zero temperatures. In this study cryomicroscopy was used. Mesenchymal stromal cells (MSCs) from bone marrow were analysed. The determined membrane hydraulic permeability for sub-zero temperatures is significantly lower than that for supra-zero temperatures. On the contrary the activation energy is significantly higher in the presence of ice. The addition of a cryoprotective agent (CPA) such as dimethyl sulfoxid (DMSO) shows an additional influence on the characteristics of the membrane of the cell. The optimal cooling rate was determined with these parameters. For cryopreservation without DMSO the optimal cooling rate was found to be 12.82 K/min. If the MSCs were frozen with 5% (v/v) DMSO the optimal cooling rate is 16.25 K/min.

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Wei, Rui Li. "New Research Progress in Activation of Steel Slag Activity." Advanced Materials Research 1030-1032 (September 2014): 125–29. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.125.

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Steel slag has potential hydraulic reactivity, it can replace raw material for making cement clinker, or directly product slag cement as admixture, but there is a problem that it has a lower activity as the admixture to produce slag cement. The reasons for lower activity of steel slag and motivation of steel slag activity were discussed in detail.

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Chong, Zhaohui, Xuehua Li, and Xiangyu Chen. "Effect of Injection Site on Fault Activation and Seismicity during Hydraulic Fracturing." Energies 10, no. 10 (October 16, 2017): 1619. http://dx.doi.org/10.3390/en10101619.

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Kriskova, Lubica, Yiannis Pontikes, Özlem Cizer, Gilles Mertens, Wout Veulemans, Daneel Geysen, Peter Tom Jones, Lucie Vandewalle, Koen Van Balen, and Bart Blanpain. "Effect of mechanical activation on the hydraulic properties of stainless steel slags." Cement and Concrete Research 42, no. 6 (June 2012): 778–88. http://dx.doi.org/10.1016/j.cemconres.2012.02.016.

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El Fami, Nisrine, Hassan Ez-zaki, Abdeljebbar Diouri, Omar Sassi, and Ali Boukhari. "Improvement of hydraulic and mechanical properties of dicalcium silicate by alkaline activation." Construction and Building Materials 247 (June 2020): 118589. http://dx.doi.org/10.1016/j.conbuildmat.2020.118589.

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Antunes, Mónica, Rodrigo Lino Santos, João Pereira, Ricardo Bayão Horta, Patrizia Paradiso, and Rogério Colaço. "The Apparent Activation Energy of a Novel Low-Calcium Silicate Hydraulic Binder." Materials 14, no. 18 (September 16, 2021): 5347. http://dx.doi.org/10.3390/ma14185347.

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In this work, the apparent activation energy (Ea) of a novel low-calcium binder was, for the first time, experimentally determined, using a calorimetric approach. Additionally, a correlation between the Ea, measured at the acceleration period with the C/S ratio of the hydration product is proposed. The Ea of the prepared pastes was determined through isothermal calorimetry tests by calculating the specific rate of reaction at different temperatures, using two different approaches. When comparing the Ea, at the acceleration period of this novel binder with the one published for alite and belite, we observed that its value is higher, which may be a result of a different hydration product formed with a distinct C/S ratio. Finally, to study the temperature effect on the compressive strength at early ages, a set of experiments with mortars was performed. The results showed that the longer the curing time at 35 °C, the higher the compressive strength after 2 days of hydration, which suggests a higher initial development of hydration products. This study also indicated that the novel binder has a higher sensitivity to temperature when compared with ordinary Portland cement (OPC).

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14

Kumar, Sanjay, A. Bandopadhyay, T. C. Alex, and Rakesh Kumar. "Influence of mechanical activation on the synthesis and hydraulic activity of calcium dialuminate." Ceramics International 32, no. 5 (January 2006): 555–60. http://dx.doi.org/10.1016/j.ceramint.2005.04.017.

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15

Haddad, Mahdi, Jing Du, and Sandrine Vidal-Gilbert. "Integration of Dynamic Microseismic Data With a True 3D Modeling of Hydraulic-Fracture Propagation in the Vaca Muerta Shale." SPE Journal 22, no. 06 (August 4, 2017): 1714–38. http://dx.doi.org/10.2118/179164-pa.

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Summary Microseismic mapping during the hydraulic-fracturing processes in the Vaca Muerta (VM) Shale in Argentina shows a group of microseismic events occurring at shallower depth and at later injection time, and they clearly deviate from the growing planar hydraulic fracture. This spatial and temporal behavior of these shallow microseismic events incurs some questions regarding the nature of these events and their connectivity to the hydraulic fracture. To answer these questions, in this article, we investigate these phenomena by use of a true 3D fracture-propagation-modeling tool along with statistical analysis on the properties of microseismic events. First, we propose a novel technique in Abaqus incorporating fracture intersections in true 3D hydraulic-fracture-propagation simulations by use of a pore-pressure cohesive zone model (CZM), which is validated by comparing our numerical results with the Khristianovic-Geertsma-de Klerk (KGD) solution (Khristianovic and Zheltov 1955; Geertsma and de Klerk 1969). The simulations fully couple slot flow in the fracture with poroelasticity in the matrix and continuum-based leakoff on the fracture walls, and honor the fracture-tip effects in quasibrittle shales. By use of this model, we quantify vertical-natural-fracture activation and fluid infiltration depending on reservoir depth, fracturing-fluid viscosity, mechanical properties of the natural-fracture cohesive layer, natural-fracture conductivity, and horizontal stress contrast. The modeling results demonstrate this natural-fracture activation in coincidence with the hydraulic-fracture-growth complexities at the intersection, such as height throttling, sharp aperture reduction after the intersection, and multibranching at various heights and directions. Finally, we investigate the hydraulic-fracture intersection with a natural fracture in the multilayer VM Shale. We infer the natural-fracture location and orientation from the microseismic-events map and formation microimager log in a nearby vertical well, respectively. We integrate the other field information such as mechanical, geological, and operational data to provide a realistic hydraulic-fracturing simulation in the presence of a natural fracture. Our 3D fracturing simulations equipped with the new fracture-intersection model rigorously simulate the growth of a realistic hydraulic-connection path toward the natural fracture at shallower depths, which was in agreement with our microseismic observations.

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SHULTZ, JEFFREY W. "Muscle Firing Patterns in two Arachnids using different methods of Propulsive Leg Extension." Journal of Experimental Biology 162, no. 1 (January 1, 1992): 313–29. http://dx.doi.org/10.1242/jeb.162.1.313.

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Activity patterns of six morphologically similar, homologous muscles were recorded from the fourth leg pair in two species of arachnids that use different mechanisms to extend the femur-patella (knee) joint during locomotion. The giant whipscorpion Mastigoproctus giganteus (Uropygi) lacks femur-patella extensor muscles but extends this joint with hydraulic pressure, a mechanism that appears to be phylogenetically primitive in arachnids. The black emperor scorpion Pandinus imperator (Scorpiones) has an unusual muscle that promotes simultaneous extension at the femur-patella joint and distally adjacent patella-tibia joint. Comparison of electromyograms from freely walking animals revealed similarities in muscle firing patterns of the two species, including asymmetrical alternation of trochanter-femur levator and depressor muscles, transfemoral muscle activation during protraction and abrupt termination just prior to levator activation, and persistence of flexor activity during retraction (extension). These results indicate that the apparent evolutionary transition from hydraulic to muscular extension occurred without substantial alteration of several components of the primitive motor programme. It is suggested that the patterns of extension force generated by hydraulic pressure and by bifunctional extensors are similar and that this similarity is associated with conservation of the motorprogramme.

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Murphy, Taylor A., and Michele L. Oliver. "Hydraulic-actuation joystick use: A torque, range of motion and electromyographic description." Occupational Ergonomics 7, no. 3 (January 11, 2008): 201–13. http://dx.doi.org/10.3233/oer-2007-7305.

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The purpose of this work was to quantify upper limb and joystick kinematics, muscle activation of the prime movers and stabilizers of the shoulder (anterior deltoid, posterior deltoid and upper trapezius) as well as torque exerted by operators of hydraulic-actuation joystick controllers. Dynamic and impact torques were captured through the use of an instrumented joystick. Results indicate that the impact torque (5.36 ± 1.75 N·m for forward motion) sustained as the joystick reaches the end range of motion is substantial and is more than twice that of the operator exerted torque prior to reaching the hard endpoint. EMG data confirm that the upper trapezius is in a state of constant but low level activation, which may be largely attributable to postural demands forced upon the operator by the armrest.

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18

Zhao, Runchen, Alexandros Afthinos, Tian Zhu, Panagiotis Mistriotis, Yizeng Li, Selma A. Serra, Yuqi Zhang, et al. "Cell sensing and decision-making in confinement: The role of TRPM7 in a tug of war between hydraulic pressure and cross-sectional area." Science Advances 5, no. 7 (July 2019): eaaw7243. http://dx.doi.org/10.1126/sciadv.aaw7243.

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How cells sense hydraulic pressure and make directional choices in confinement remains elusive. Using trifurcating Ψ-like microchannels of different hydraulic resistances and cross-sectional areas, we discovered that the TRPM7 ion channel is the critical mechanosensor, which directs decision-making of blebbing cells toward channels of lower hydraulic resistance irrespective of their cross-sectional areas. Hydraulic pressure–mediated TRPM7 activation triggers calcium influx and supports a thicker cortical actin meshwork containing an elevated density of myosin-IIA. Cortical actomyosin shields cells against external forces and preferentially directs cell entrance in low resistance channels. Inhibition of TRPM7 function or actomyosin contractility renders cells unable to sense different resistances and alters the decision-making pattern to cross-sectional area–based partition. Cell distribution in microchannels is captured by a mathematical model based on the maximum entropy principle using cortical actin as a key variable. This study demonstrates the unique role of TRPM7 in controlling decision-making and navigating migration in complex microenvironments.

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19

He, Zhenhua, and Benchun Duan. "Dynamic modeling of bedding-plane slip during hydraulic fracturing." GEOPHYSICS 84, no. 3 (May 1, 2019): KS95—KS104. http://dx.doi.org/10.1190/geo2018-0170.1.

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Whether the tip stresses around a dynamically propagating hydraulic fracture (HF) could activate a bedding plane (BP) or not is an important question for HF propagation and microseismicity generation. BP slip has been proposed to be one main source of microseismicity during HF treatments in unconventional reservoirs. However, a BP perpendicular to a principal stress direction is unlikely to be activated in a simple geomechanical model. We have applied a dynamic finite-element geomechanics method to examine the induced dynamic shear stress and the activation of BPs that are perpendicular to the HF based on the Cotton-Valley tight-sand reservoir properties. We work in a 2D vertical-plane framework. The induced dynamic stresses around a HF tip could be significant. We explore three different scenarios for the BP activation. In the first scenario, an HF is dynamically propagating toward two symmetric BPs, but has not touched them yet. We find that only low-strength BPs can be activated in this scenario. In the second scenario, an HF dynamically propagates toward two symmetric BPs and then it crosses them by a short distance. The BPs could be more easily activated in this scenario compared with the first scenario. The slip length and maximum slip decrease with cohesion, critical slip distance, or maximum principal stress. In the third scenario, an HF dynamically propagates toward two symmetric BPs, and then fluid invasion into the BPs occurs after the HF touches them. Large shear slippage and slip length happen in this scenario because fluid invasion weakens the BPs. In all of the scenarios, different senses of shear could occur along the BPs and a rupture typically propagates bilaterally from the initiation point on the BPs.

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20

Ghofrani, Hadi, and Gail M. Atkinson. "Activation Rate of Seismicity for Hydraulic Fracture Wells in the Western Canada Sedimentary Basin." Bulletin of the Seismological Society of America 110, no. 5 (May 12, 2020): 2252–71. http://dx.doi.org/10.1785/0120200002.

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ABSTRACT The rate of M≥3 earthquakes associated with hydraulic fracturing (HF) in horizontal wells (HF wells) in the Western Canada Sedimentary Basin is estimated for the period from 2009 to 2019. The estimates are based on a statistical discrimination algorithm that uses an objective scoring function deduced from the observed spatiotemporal correlations between wells and earthquakes. A Monte Carlo simulation approach is used to test the efficacy of the scoring function in determining noncoincidental association rates, allowing for correction of the observed association rates for the expected number of false positives. The basin-wide average rate of association of M≥3 earthquakes with HF wells (2009–2019) is ∼0.8% on a per well basis. The susceptibility appears to vary by formation by more than an order of magnitude, ranging from ∼6% for HF wells in the Duvernay Formation to ∼0.07% for HF wells in the Cardium Formation. For some formations, there has been no observed association at the M≥3 level to date, but this does not necessarily imply that such formations are immune to induced seismicity.

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Santos, Rodrigo L., Ricardo B. Horta, João Pereira, Teresa G. Nunes, Paulo Rocha, and Rogério Colaço. "Alkali activation of a novel calcium‐silicate hydraulic binder with CaO/SiO 2 = 1.1." Journal of the American Ceramic Society 101, no. 9 (April 14, 2018): 4158–70. http://dx.doi.org/10.1111/jace.15554.

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22

Kriskova, Lubica, Yiannis Pontikes, Fei Zhang, Özlem Cizer, Peter Tom Jones, Koenraad Van Balen, and Bart Blanpain. "Influence of mechanical and chemical activation on the hydraulic properties of gamma dicalcium silicate." Cement and Concrete Research 55 (January 2014): 59–68. http://dx.doi.org/10.1016/j.cemconres.2013.10.004.

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23

Mec, Pavel, Jana Boháčová, and Josef Koňařík. "Comparison of Selected Properties of Portland Cement Based Materials and Alkali Activated Materials Based on Granulated Blast Furnace Slag." Materials Science Forum 865 (August 2016): 107–13. http://dx.doi.org/10.4028/www.scientific.net/msf.865.107.

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Alkali activated systems are materials formed by alkali-activation of latent hydraulic or pozzolanic materials. The outcome is a polymeric structure with properties comparable to materials based on cement.The principle of the experiment is to compare selected properties of alkali-activated materials based on blast furnace slag and using various types of activator (sodium water glass, potassium water glass, DESIL AL and sodium metasilicate) to binders based on white and Portland cements of the highest quality. The samples were left for one year in environments simulating the conditions in the interior and exterior. Selected physical-mechanical properties were evaluated and compared.

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Van Gemert, Dionys, and Özlem Cizer. "Combining Mineral and Polymer Binder Material Science for Sustainability in Construction and Restoration." Restoration of Buildings and Monuments 21, no. 4-6 (December 1, 2015): 149–64. http://dx.doi.org/10.1515/rbm-2015-2001.

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Abstract The study of microstructure formation in polymer-cement concrete provides opportunities to exploit synergetic actions between cement and polymer, leading to performance improvement and to a wide range of new and innovative properties and applications. Polymers can reduce the impact of construction industry on environment, by decreasing the carbon footprint of cement and concrete production. Renovation and restoration, largely figuring in the concept of sustainable construction development, thank their growing share in construction activity to the input of polymers in repair and binder materials and in rehabilitation procedures. The study of ancient binders and mortars reveals aspects of the origins of the observed long lasting durability of those ancient mortars. It also reveals the interaction mechanisms between carbonation of air hardening components and hydration of hydraulic components, which in turn helps to develop chemical activation methods (i.e. alkaline activation) to improve the hydraulic properties of pozzolans and industrial residues to develop inorganic polymers (i.e. geopolymers) for eventually full replacement of cement in binders.

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Staněk, Theodor, Martin Boháč, and Petr Sulovský. "Chemical Activation of Dicalcium Silicate and its Use for Cement Production." Advanced Materials Research 1151 (March 2019): 17–21. http://dx.doi.org/10.4028/www.scientific.net/amr.1151.17.

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In this work, it was found out that dicalcium silicate doped with SO3 shows higher hydraulic activity compared to pure dicalcium silicate. This finding was used to prepare and optimize high-belite cement from SO3 doped clinkers. The belite cement exhibited the same technological parameters, including short-term strengths, as ordinary Portland cement with a high content of tricalcium silicate. The clinker for belite cement is environmentally and economically advantageous. It is possible to burn the clinker at a temperature of 100 °C lower than conventional clinker and with lower consumption of calcium carbonate. In particular, methods of optical and electron microscopy were used for the research.

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Kettlety, Tom, James P. Verdon, Antony Butcher, Matthew Hampson, and Lucy Craddock. "High-Resolution Imaging of the ML 2.9 August 2019 Earthquake in Lancashire, United Kingdom, Induced by Hydraulic Fracturing during Preston New Road PNR-2 Operations." Seismological Research Letters 92, no. 1 (October 28, 2020): 151–69. http://dx.doi.org/10.1785/0220200187.

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Abstract Hydraulic fracturing (HF) at Preston New Road (PNR), Lancashire, United Kingdom, in August 2019, induced a number of felt earthquakes. The largest event (ML 2.9) occurred on 26 August 2019, approximately three days after HF operations at the site had stopped. Following this, in November 2019, the United Kingdom Government announced a moratorium on HF for shale gas in England. Here we provide an analysis of the microseismic observations made during this case of HF-induced fault activation. More than 55,000 microseismic events were detected during operations using a downhole array, the vast majority measuring less than Mw 0. Event locations revealed the growth of hydraulic fractures and their interaction with several preexisting structures. The spatiotemporal distribution of events suggests that a hydraulic pathway was created between the injection points and a nearby northwest–southeast-striking fault, on which the largest events occurred. The aftershocks of the ML 2.9 event clearly delineate the rupture plane, with their spatial distribution forming a halo of activity around the mainshock rupture area. Across clusters of events, the magnitude distributions are distinctly bimodal, with a lower Gutenberg–Richter b-value for events above Mw 0, suggesting a break in scaling between events associated with hydraulic fracture propagation, and events associated with activation of the fault. This poses a challenge for mitigation strategies that rely on extrapolating microseismicity observed during injection to forecast future behavior. The activated fault was well oriented for failure in the regional stress field, significantly more so than the fault activated during previous operations at PNR in 2018. The differing orientations within the stress field likely explain why this PNR-2 fault produced larger events compared with the 2018 sequence, despite receiving a smaller volume of injected fluid. This indicates that fault orientation and in situ stress conditions play a key role in controlling the severity of seismicity induced by HF.

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Antolín-Urbaneja, J. C., J. Lasa, P. Estensoro, I. Cabanes, and M. Marcos. "Innovative Hydraulic Power Take-Off Construction and Performance Tests for Wave Energy Conversion." Applied Mechanics and Materials 432 (September 2013): 316–23. http://dx.doi.org/10.4028/www.scientific.net/amm.432.316.

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This document describes and demonstrates the features of a new innovative hydraulic Power take-Off (PTO) to be used for Wave Energy Conversion. This device is able to transform low frequency oscillating movement into a continuous high frequency angular speed, absorbing high fluctuated torque at the input shaft, which can reach up to 8000Nm. Moreover, the major breakthrough of this device is that it can control the braking torque through the modification of some geometrical parameters, L and R, and through the activation of more than one hydraulic cylinder together with the pressure. The output shaft of the PTO is able to rotate at different continuous rated speed through the actuation on a specific control valve at the inlet of the hydraulic motor. Tests to check the behavior of the PTO related to the smoothening of the power output and concerning the time needed to increase the high pressure and the time available after the accumulation of some quantity of energy in different initial conditions are presented.

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Gruyaert, Elke, Kim Van Tittelboom, Hubert Rahier, and Nele De Belie. "Activation of Pozzolanic and Latent-Hydraulic Reactions by Alkalis in Order to Repair Concrete Cracks." Journal of Materials in Civil Engineering 27, no. 7 (July 2015): 04014208. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0001162.

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Rutledge, James T., and W. Scott Phillips. "Hydraulic stimulation of natural fractures as revealed by induced microearthquakes, Carthage Cotton Valley gas field, east Texas." GEOPHYSICS 68, no. 2 (March 2003): 441–52. http://dx.doi.org/10.1190/1.1567214.

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We produced a high‐resolution microseismic image of a hydraulic fracture stimulation in the Carthage Cotton Valley gas field of east Texas. We improved the precision of microseismic event locations four‐fold over initial locations by manually repicking the traveltimes in a spatial sequence, allowing us to visually correlate waveforms of adjacent sources. The new locations show vertical containment within individual, targeted sands, suggesting little or no hydraulic communication between the discrete perforation intervals simultaneously treated within an 80‐m section. Treatment (i.e., fracture‐zone) lengths inferred from event locations are about 200 m greater at the shallow perforation intervals than at the deeper intervals. The highest quality locations indicate fracture‐zone widths as narrow as 6 m. Similarity of adjacent‐source waveforms, along with systematic changes of phase amplitude ratios and polarities, indicate fairly uniform source mechanisms (fracture plane orientation and sense of slip) over the treatment length. Composite focal mechanisms indicate both left‐ and right‐lateral strike‐slip faulting along near‐vertical fractures that strike subparallel to maximum horizontal stress. The focal mechanisms and event locations are consistent with activation of the reservoir's prevalent natural fractures, fractures that are isolated within individual sands and trend subparallel to the expected hydraulic fracture orientation (maximum horizontal stress direction). Shear activation of these fractures indicates a stronger correlation of induced seismicity with low‐impedance flow paths than is normally found or assumed during injection stimulation.

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Jaffe, Mordecai J., and A. Carl Leopold. "Light Activation of Contractile Roots of Easter Lily." Journal of the American Society for Horticultural Science 132, no. 5 (September 2007): 575–82. http://dx.doi.org/10.21273/jashs.132.5.575.

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Contractile roots provide for a type of movement in plants that occurs in many plant species but has been given little attention. In the case of Easter lily (Lilium longiflorum Thunb. cv. Nelly White), root contraction serves to pull a bulb down into the soil where environmental conditions are more constant. The contraction is evidenced by a formation of epidermal wrinkles, starting at the base of the root and advancing toward the root tip. The movement function occurs in shallowly planted materials, is lessened at deeper locations, and ceases at a vermiculite depth of ≈15 cm. Examination of the cell shapes and volumes in the contracting sector indicates that movement of the bulb in the soil is achieved by a hydraulic shift in cortical cells. Root contraction is stimulated by light. Perception of the light stimulus does not occur in the root but occurs in the bulblet or possibly in the subtending leaf. Responsiveness to light fades with aging of the root, and experiments with light of different wavelengths indicate that the contraction response is preferentially triggered by blue light.

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31

Handayani, Retno, and Erman Taer. "PENGARUH WAKTU AKTIVASI TERHADAP SIFAT FISIS DAN ELEKTROKIMIA SEL SUPERKAPASITOR DARI SABUT PINANG." Komunikasi Fisika Indonesia 16, no. 2 (October 31, 2019): 87. http://dx.doi.org/10.31258/jkfi.16.2.87-90.

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The Carbon electrodes made from areca husk biomass materials have been successfully prepared and characterized. Preparation of carbon electrodes start with the pre-carbonization process, destruction of pre-carbon samples by using Ball Milling and sieving carbon powder for resulting particle size of <53 µm. Pre-carbonized powder is chemically activated using a 0.5 M KOH activator and continued by pellet forming by using Hydraulic Press. The carbonization process was carried out at a temperature of 600 oC using N2 gas followed by physical activation by using CO2 gas with a temperature of 900 oC for 1.5 hours, 2 hours and 2.5 hours. Physical properties analyzed include density, morphological structure and elemental content. The electrochemical properties were analyzed using the cyclic voltammetry (CV) method. The best density analysis result after carbonization-activation is 0.664 in SP-2.5 sample. The highest specific capacitance as high as 17.9 F / g found in the SP-1.5 sample.

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Boronenko, Marina P., Vitalii V. Lavrikov, Aleksandr E. Seregin, Paul A. Yurukin, and Roman F. Yuhimyk. "Energy control and grinding mechanoactivation planetary mill AGO-3." Yugra State University Bulletin 12, no. 2 (June 15, 2016): 7–16. http://dx.doi.org/10.17816/byusu20161227-16.

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For laboratory mehanoaktivatora AGO-3 the parameters of thermal and energy intensity depending on the level filling the container carrier velocity, time mechanical activation. Determine the power delivered to the grinding bodies, friction losses and hydraulic resistance movement of the containers. The reported study was funded by RFBR according to the research project No. 15-42-00106.

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Gong, Chen Chen, and Dong Xu Li. "Influence on Activation Property of Calcined Coal Gangue by [SO4]²⁺." Advanced Materials Research 306-307 (August 2011): 1757–60. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.1757.

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Coal gangue and limestone were used as raw materials with fluorite and gypsum as the mineralizer. The activation mechanism of calcined coal gangue with calcium and the pore structure of its hydrating slurry are discussed. The experimental results show that during calcinations F- and [SO4]2- come into the framework and react deeper with CaO at 850-950°C to create hydraulic-activity C12A7 and C2S. Pore structure analysis of the hydrating slurry indicates that adding gypsum and fluorite into coal gangue is more propitious to strengthen the slurry and optimize the pore distribution than only of gypsum.

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Eyre, Thomas S., David W. Eaton, Dmitry I. Garagash, Megan Zecevic, Marco Venieri, Ronald Weir, and Donald C. Lawton. "The role of aseismic slip in hydraulic fracturing–induced seismicity." Science Advances 5, no. 8 (August 2019): eaav7172. http://dx.doi.org/10.1126/sciadv.aav7172.

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Models for hydraulic fracturing–induced earthquakes in shales typically ascribe fault activation to elevated pore pressure or increased shear stress; however, these mechanisms are incompatible with experiments and rate-state frictional models, which predict stable sliding (aseismic slip) on faults that penetrate rocks with high clay or total organic carbon. Recent studies further indicate that the earthquakes tend to nucleate over relatively short injection time scales and sufficiently far from the injection zone that triggering by either poroelastic stress changes or pore pressure diffusion is unlikely. Here, we invoke an alternative model based on recent laboratory and in situ experiments, wherein distal, unstable regions of a fault are progressively loaded by aseismic slip on proximal, stable regions stimulated by hydraulic fracturing. This model predicts that dynamic rupture initiates when the creep front impinges on a fault region where rock composition favors dynamic and slip rate weakening behavior.

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Wang, Yinghao, Jianfeng Wu, Hongchun Yang, Zhichuan Tang, and Guozhong Chai. "Evaluation of a New Rotator Cuff Trainer Based on Oscillating Hydraulic Damping." Healthcare 8, no. 1 (January 28, 2020): 24. http://dx.doi.org/10.3390/healthcare8010024.

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In order to provide a convenient way to strengthen the rotator cuff muscles and prevent rotator cuff injury, this study designed an innovative strength trainer specifically for shoulder rotator cuff based on oscillating hydraulic damping. We carried out a myoelectric testing experiment to evaluate the shoulder rotation training effect and compared the results with traditional training equipment to verify the feasibility and validity of the new rotator cuff trainer (RCT). Then, we further explored the influence of different training postures and motion speeds on shoulder rotation training. In the experiment, subjects used three types of equipment (RCT, dumbbells and elastic bands) to perform shoulder rotation training under two movement speeds and two motion postures. The surface electromyography (sEMG) signals of targeted muscles were collected in real time and then further analyzed. The experimental results showed that when using the RCT, the muscle force generation sequence was more aligned with the biomechanical principles of shoulder rotation than using the other two training methods, and the target training muscles had the higher percentage of muscle work. During RCT training, a higher speed of movement (120°/s) led to a higher degree of muscle activation; coronal axis rotation was better for the infraspinatus training, and sagittal axis rotation was better for teres minor training. Based on these results, the RCT was proved to be more effective than traditional training methods. In order to exercise the different muscles of rotator cuff more comprehensively and extensively, different postures should be selected. Furthermore, the movement speed can be appropriately increased within the safe range to improve muscle activation.

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Tommasi, Paolo, Daniela Boldini, Giada Caldarini, and Niccolò Coli. "Influence of infiltration on the periodic re-activation of slow movements in an overconsolidated clay slope." Canadian Geotechnical Journal 50, no. 1 (January 2013): 54–67. http://dx.doi.org/10.1139/cgj-2012-0121.

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In Orvieto (central Italy), overconsolidated clay slopes are affected by intermittent slow movements at the top of the clay formation and within the landslide debris cover. Monthly data from inclinometers, Casagrande piezometers, and rainfall gauges show that velocity, pore pressure, and rainfall are closely related. A relationship is suggested to predict slope re-activation using rainfall history alone, once a pore pressure threshold has been reached and response of pore pressures to rainfall is understood. Pore pressures have been continuously monitored through vibrating wire cells. The threshold for shallow movements, critical for infrastructures and buildings, was identified by comparing displacement histories of a shallow movement, representative of many other ones recognized over the slope, and pore pressure, both measured at the centre of the sliding mass. The impact of infiltrated rainfall on groundwater flow was investigated through transient seepage analyses. Seepage analyses performed using hydraulic properties from laboratory and in situ tests do not fully depict the observed pore pressures because field data miss some structural characters and lithologic variations. The hydraulic properties of the shallower model layers were refined, based on field observations and interpretation of monitoring data, to have a good match between computed and measured pore pressures. Once the model is tested at different locations along a slope, it could be used to predict movement re-activation using only rainfall data.

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Li, Zheng, Jingyi Wang, and Ian D. Gates. "Fracturing Gels as Analogs to Understand Fracture Behavior in Shale Gas Reservoirs." Rock Mechanics and Rock Engineering 53, no. 10 (May 25, 2020): 4345–55. http://dx.doi.org/10.1007/s00603-020-02153-9.

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Abstract Hydraulic fracturing is widely used in the exploitation of unconventional reservoirs, such as shale gas and tight gas. However, a full understanding of the activation of natural fractures, prediction of fracture growth, distribution of proppant, and network fracture system effectiveness remain unresolved. The onset of fracturing in the media requires energy and this is due to the buildup of pressure within the rock due to continuous injection of fluid. In other words, when the energy associated with the injection fluid reaches the fracture strength of the rock, the fracture initiates and propagates into the formation. Here, we use gelatin in hydraulic fracturing laboratory tests and compare the results to a modified radial hydraulic fracturing theory. The mechanics of the gelatin, procedures to make a testing gelatin block, and procedures to conduct the test are described. The results show that the fracture evolving behaviours from experiments are well matched by the theory. The results are then scaled up to understand fracture growth behaviour in a tight rock reservoir.

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Taleghani, A. Dahi, M. Ahmadi, W. Wang, and Jon E. Olson. "Thermal Reactivation of Microfractures and Its Potential Impact on Hydraulic-Fracture Efficiency." SPE Journal 19, no. 05 (February 20, 2014): 761–70. http://dx.doi.org/10.2118/163872-pa.

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Summary Core studies have revealed the presence of abundant cemented microfractures in many tight formations. Further independent studies have revealed the opening of some of these microfractures on the wall surface of main hydraulic fractures. In addition, early-production well-testing analysis in some of these cases provides estimates for the hydraulically-induced-fracture surface area, which is much larger than fracture dimensions estimated in fracturing design or provided by the location of microseismic events. Opening of small-sized fractures could be a possible reason for this discrepancy. In this paper, we show to what extent thermal stresses induced by temperature difference between fracturing fluid and formation fluid could provide the driving force to open a portion of these small, cemented natural fractures lying on the surface of hydraulic fractures. Moreover, through combination of stress analysis and empirical fracture-distribution models obtained from outcrops, we calculate the increase of total reservoir/fracture contact surface under the condition of microfracture activation. Our thermoelasticity analysis reveals the effect of the pump rate and temperature of the fracturing fluid on the number of activated microfractures. The results show that the volume of the microfractures varies depending on the length of the microfracture, rock properties, and time. At the end of the paper, through an example, we show that activation of only a small portion of these microfractures can increase the total fracture/formation contact area considerably and, consequently, increase initial production. Reservoir-pressure changes caused by production might partially close or reopen these microcracks during production; hence, the effectiveness of these microfractures could be mainly restricted to the early life of the reservoirs.

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Pazur, R. J., J. G. Cormier, and K. Korhan-Taymaz. "SERVICE LIFE DETERMINATION OF NITRILE O-RINGS IN HYDRAULIC FLUID." Rubber Chemistry and Technology 87, no. 2 (June 1, 2014): 239–49. http://dx.doi.org/10.5254/rct.13.87916.

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ABSTRACT The service life of nitrile O-rings exposed to hydraulic fluid was determined by accelerated aging at nine temperatures and four immersion times. Tensile mechanical properties (elongation and low strain modulus), volume swell, compression set, and chemical crosslink density by solvent swell were measured. Calculated activation energies based on Arrhenius rate behavior ranged from 52 to 65 kJmol−1, approximately 20–30 kJmol−1 lower than nitrile rubber heat aged in air environments. Using a 50% loss of elongation as a failure criterion, an estimate of 15 yr of service life at 23 °C was calculated. This corresponds to a compression set of 50% and an increase of approximately 30% of the chemical crosslink density. Replacement of the plasticizer with the mineral oil and its additives increased total inorganic levels in degraded O-rings as measured by thermogravimetric analysis. Besides additional sulfur and sodium, energy dispersive spectroscopy identified the presence of phosphorous, chlorine, and potassium. Hydraulic oil additives are likely responsible in facilitating the O-ring degradation through lower energy pathways that accelerate nitrile rubber hardening.

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Lerch, Werner, Richard Heimrath, Andreas Heinz, Thomas Mach, Christian Fink, and Thomas Ramschak. "Efficiency Increase of Solar Heated Buildings by Thermal Activation of Construction Elements." Applied Mechanics and Materials 887 (January 2019): 659–66. http://dx.doi.org/10.4028/www.scientific.net/amm.887.659.

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The Austrian project “solSPONGEhigh” [1] examines the use of thermal activation of building components in order to increase the solar fraction of the heat demand of buildings. The aim of the project is to evaluate, under which conditions a high solar fraction of a single family house (low energy building) can be achieved with solar technologies (PV and solar thermal, in this paper the focus is on solar thermal). Different heat supply systems based on solar thermal energy (basic or complex supply systems) have been defined. The systems were modeled in the simulation environment TRNSYS [2], analyzed concerning their system behavior and further developed. The investigated systems range from classical monovalent heat supply systems, systems combined with solar thermal up to complex integrated hydraulic solutions. The heating of the building via concrete core activation was compared with a conventional underfloor heating system. A detailed analysis of the dynamic system and building simulation results shows that the system efficiency can be significantly increased, if solar heat is used to charge the storage capacity of the building structure directly. A further advantage when activating the building structure (primarily concrete) is the less rapidly changing room air temperature with strongly fluctuating environmental conditions.

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Zorina, Kseniia, Maria Vasilieva, Igor Babikov, and Anton Tanklevskiy. "Comparison of technical-economic performance of traditional and innovational sprinkler extinguishing units." MATEC Web of Conferences 245 (2018): 11002. http://dx.doi.org/10.1051/matecconf/201824511002.

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One of the most important tasks during construction and maintenance of buildings and compartments is a fire-safety provision of the premise. Generally, the most reliable, effective and economical method of fire safety provision is implementation of automatic extinguishing units (AEU), water-based ones in particular, which effectively protect people and material assets. The present article contains an economic evaluation of applicability of innovational AEU with electrical activation and monitoring of activation (AEU with EA and MA) in comparison with traditional AEU. Results of hydraulic calculations, the choice of a general pressure of the system, water discharge, pipeline diameter and their cost are presented.

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Salah, Mohammed, M. Abdel-Rahman, Emad A. Badawi, and M. A. Abdel-Rahman. "Determination of the activation enthalpy for migration of dislocations in plastically deformed 8006 Al-alloy by positron annihilation lifetime technique." International Journal of Modern Physics B 30, no. 18 (July 11, 2016): 1650110. http://dx.doi.org/10.1142/s0217979216501101.

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The activation enthalpy for migration of dislocations of plastically deformed 8006 Al-alloy was investigated by positron annihilation lifetime technique. Plastic deformation using a hydraulic press produces mainly dislocations and may produce point defects. The type of defect was studied by isochronal annealing which determines the temperature range of recovery of each type. Only one type of defect (dislocations) was observed for the investigated sample and was found to be recovered within the range 455–700 K. Isothermal annealing by slow cooling was performed through this range and used in determination of the activation enthalpy of migration of dislocations which was found to be 0.26 ± 0.01 eV.

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Moalli, Maria R., Suquing Wang, Nancy J. Caldwell, Pravin V. Patil, and Craig R. Maynard. "Mechanical stimulation induces pp125FAK and pp60 src activity in an in vivo model of trabecular bone formation." Journal of Applied Physiology 91, no. 2 (August 1, 2001): 912–18. http://dx.doi.org/10.1152/jappl.2001.91.2.912.

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Utilizing an in vivo model of trabecular bone formation, we demonstrated the temporal and spatial activation of pp125FAK in response to specific mechanical load stimuli. Bone chambers equipped with hydraulic actuators were aseptically inserted into each proximal tibial metaphysis of adult, male dogs under general anesthesia. The load stimulus consisted of a trapezoidal waveform, with a maximum compressive load of 17.8 N, loading rate of 89 N/s, at 1 Hz frequency. One chamber was loaded for 2 (120 cycles), 15 (900 cycles), or 30 min (1,800 cycles), whereas the contralateral chamber served as unloaded control. Bone chambers were biopsied at postload time points of 0, 15, and 45 min. Load-induced activation of FAK was rapid, and the duration of activation was dependent on the number of applied load cycles. Mechanical stimulation increased the association of FAK with Src and the time course of complex formation paralleled the temporal activation of FAK. Evaluation of cryosections revealed prominent FAK immunoreactivity among marrow fibroblasts and stromal cells.

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Šedina, Jakub, Jan Valentin, Petr Mondschein, and Jan Suda. "Alternative Micro-Milled Binders in Cold Recycling Technologies." Slovak Journal of Civil Engineering 27, no. 2 (June 1, 2019): 16–20. http://dx.doi.org/10.2478/sjce-2019-0011.

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AbstractIn addition to bituminous binders (bituminous emulsion, foamed bitumen), hydraulic binders are applied in cold recycling technologies to increase the strength of a final structural layer as well as to increase its resistance to water and frost impacts. This paper deals with the use of energy by-products from fluidized bed coal combustion and mineral waste and their modification into reactive material with the potential of replacing commonly used hydraulic binders. The increase in the reactive potential takes place through a high-speed milling process where the mechanical-chemical activation of the material takes place. This process is associated with the refinement of the material, a higher proportion of micro and nanoparticles, an increased surface area, opening of particles, etc. The material treated exhibits binding properties, and it can be used as an active filler that allows for the partial or complete substitution of hydraulic binders. The experimental part is focused on the application of alternative binders to cold recycling mixtures and their assessment according to valid technical regulations, i.e., an assessment of their indirect tensile strength and water susceptibility as well as compressive strength and resistance to the effects of water and frost.

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Devireddy, Ram V., Sreedhar Thirumala, and Jeffrey M. Gimble. "Cellular Response of Adipose Derived Passage-4 Adult Stem Cells to Freezing Stress." Journal of Biomechanical Engineering 127, no. 7 (July 13, 2005): 1081–86. http://dx.doi.org/10.1115/1.2073673.

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A differential scanning calorimeter technique was used to generate experimental data for volumetric shrinkage during cooling at 20°C∕min in adipose derived adult stem cells (ASCs) in the presence and absence of cryoprotective agents (CPAs). By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the membrane permeability parameters of ASCs were obtained. For passage-4 (P4) ASCs, the reference hydraulic conductivity Lpg and the value of the apparent activation energy ELp were determined to be 1.2×10−13m3∕Ns and 177.8kJ∕mole, respectively. We found that the addition of either glycerol or dimethylsulfoxide (DMSO) significantly decreased the value of the reference hydraulic conductivity Lpg(cpa) and the value of the apparent activation energy ELp(cpa) in P4 ASCs. The values of Lpg(cpa) in the presence of glycerol and DMSO were determined as 0.39×10−13 and 0.50×10−13m3∕Ns, respectively, while the corresponding values of ELp(cpa) were 51.0 and 61.5kJ∕mole. Numerical simulations of water transport were then performed under a variety of cooling rates (5-100°C∕min) using the experimentally determined membrane permeability parameters. And finally, the simulation results were analyzed to predict the optimal rates of freezing P4 adipose derived cells in the presence and absence of CPAs.

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Kim, Suju, Ugochukwu Ejike Akpudo, and Jang-Wook Hur. "A Cost-Aware DNN-Based FDI Technology for Solenoid Pumps." Electronics 10, no. 19 (September 22, 2021): 2323. http://dx.doi.org/10.3390/electronics10192323.

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Fluid Pumps serve a critical function in hydraulic and thermodynamic systems, and this often exposes them to prolonged use, leading to fatigue, stress, contamination, filter clogging, etc. On one hand, vibration monitoring for hydraulic components has shown reliable efficiencies in fault detection and isolation (FDI) practices. On the other hand, signal processing techniques provide reliable FDI parameters for artificial intelligence (AI)-based data-driven diagnostics (and prognostics) and have recently attracted global interest across different disciplines and applications. Particularly for cost-aware systems, the choice of diagnostic parameters determines the reliability of an FDI/diagnostic model. By extracting (and selecting) discriminative spectral and transient features from solenoid pump vibration signals, accurate diagnostics across operating conditions can be achieved using AI-based FDI algorithms. This study employs a deep neural network (DNN) for fault diagnosis after a correlation-based selection of discriminative spectral and transient features. To solve the problem of hyperparameter selection for the proposed model, a grid search technique was employed for optimal search for parameters (number of layers, neurons, activation function, weight optimizer, etc.) on different network architectures.The results reveal the high accuracy of a three-layer DNN with ReLU activation function, with a test accuracy of 99.23% and a minimal false alarm rate on a case study.

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Minshall, Richard D., Chinnaswamy Tiruppathi, Stephen M. Vogel, Walter D. Niles, Annette Gilchrist, Heidi E. Hamm, and Asrar B. Malik. "Endothelial Cell-Surface Gp60 Activates Vesicle Formation and Trafficking via Gi-Coupled Src Kinase Signaling Pathway." Journal of Cell Biology 150, no. 5 (September 4, 2000): 1057–70. http://dx.doi.org/10.1083/jcb.150.5.1057.

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We tested the hypothesis that the albumin-docking protein gp60, which is localized in caveolae, couples to the heterotrimeric GTP binding protein Gi, and thereby activates plasmalemmal vesicle formation and the directed migration of vesicles in endothelial cells (ECs). We used the water-soluble styryl pyridinium dye N-(3-triethylaminopropyl)-4-(p-dibutylaminostyryl) pyridinium dibromide (FM 1-43) to quantify vesicle trafficking by confocal and digital fluorescence microscopy. FM 1-43 and fluorescently labeled anti-gp60 antibody (Ab) were colocalized in endocytic vesicles within 5 min of gp60 activation. Vesicles migrated to the basolateral surface where they released FM 1-43, the fluid phase styryl probe. FM 1-43 fluorescence disappeared from the basolateral EC surface without the loss of anti-gp60 Ab fluorescence. Activation of cell-surface gp60 by cross-linking (using anti-gp60 Ab and secondary Ab) in EC grown on microporous filters increased transendothelial 125I-albumin permeability without altering liquid permeability (hydraulic conductivity), thus, indicating the dissociation of hydraulic conductivity from the albumin permeability pathway. The findings that the sterol-binding agent, filipin, prevented gp60-activated vesicle formation and that caveolin-1 and gp60 were colocalized in vesicles suggest the caveolar origin of endocytic vesicles. Pertussis toxin pretreatment and expression of the dominant negative construct encoding an 11–amino acid Gαi carboxyl-terminal peptide inhibited endothelial 125I-albumin endocytosis and vesicle formation induced by gp60 activation. Expression of dominant negative Src (dn-Src) and overexpression of wild-type caveolin-1 also prevented gp60-activated endocytosis. Caveolin-1 overexpression resulted in the sequestration of Gαi with the caveolin-1, whereas dn-Src inhibited Gαi binding to caveolin-1. Thus, vesicle formation induced by gp60 and migration of vesicles to the basolateral membrane requires the interaction of gp60 with caveolin-1, followed by the activation of the downstream Gi-coupled Src kinase signaling pathway.

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Lu, Yinlong, Bingzhen Wu, Mengqi He, Lianguo Wang, Dan Ma, and Zhen Huang. "Prediction of Fracture Evolution and Groundwater Inrush from Karst Collapse Pillars in Coal Seam Floors: A Micromechanics-Based Stress-Seepage-Damage Coupled Modeling Approach." Geofluids 2020 (August 25, 2020): 1–21. http://dx.doi.org/10.1155/2020/8830304.

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Karst collapse pillars (KCPs) frequently cause severe groundwater inrush disasters in coal mining above a confined aquifer. An accurate understanding of the damage and fracture evolution, permeability enhancement, and seepage changes in KCPs under the combined action of mining-induced stress and confined hydraulic pressure is of great significance for the early prediction and prevention of groundwater inrush from KCPs in coal seam floors. In this study, a micromechanics-based coupled stress-seepage-damage (SSD) modeling approach, in which the macroscopic mechanical and hydraulic properties of the rock are explicitly related to the microcrack kinetics, is proposed to simulate the fracture evolution and the associated groundwater flow in KCPs. An in situ high-precision microseismic monitoring technology is used to verify the micromechanical modeling results, which indicate that the numerical model successfully reproduces the damage and fracture evolution in a coal seam floor with a KCP during the mining process. The presented model also provides a visual representation of the complex process of KCP activation and groundwater inrush channel formation. A numerical study shows that the damage and activation of a KCP start from the edge of the KCP, gradually develop toward the interior of the KCP, and eventually connect with the damage fracture zone of the floor, forming a primary water-conducting channel in the KCP, causing the confined groundwater to flow into the working face. Groundwater inrush from a KCP is a gradual process instead of a mutation process. A reduction in the distance between the working face and a KCP and increases in the confined hydraulic pressure and the initial water-conducting height of the KCP can significantly increase the risk of groundwater inrush from the KCP.

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Millán-Corrales, G., R. X. Magallanes-Rivera, J. R. González-López, A. A. Zaldivar-Cadena, and M. Z. Figueroa-Torres. "Synthesis of an Alternative Hydraulic Binder by Alkali Activation of a Slag from Lead and Zinc Processing." Waste and Biomass Valorization 11, no. 1 (June 16, 2018): 375–88. http://dx.doi.org/10.1007/s12649-018-0363-1.

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Niemz, Peter, Simone Cesca, Sebastian Heimann, Francesco Grigoli, Sebastian von Specht, Conny Hammer, Arno Zang, and Torsten Dahm. "Full-waveform-based characterization of acoustic emission activity in a mine-scale experiment: a comparison of conventional and advanced hydraulic fracturing schemes." Geophysical Journal International 222, no. 1 (May 1, 2020): 189–206. http://dx.doi.org/10.1093/gji/ggaa127.

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SUMMARY Understanding fracturing processes and the hydromechanical relation to induced seismicity is a key question for enhanced geothermal systems (EGS). Commonly massive fluid injection, predominately causing hydroshearing, are used in large-scale EGS but also hydraulic fracturing approaches were discussed. To evaluate the applicability of hydraulic fracturing techniques in EGS, six in situ, multistage hydraulic fracturing experiments with three different injection schemes were performed under controlled conditions in crystalline rock at the Äspö Hard Rock Laboratory (Sweden). During the experiments the near-field ground motion was continuously recorded by 11 piezoelectric borehole sensors with a sampling rate of 1 MHz. The sensor network covered a volume of 30×30×30 m around a horizontal, 28-m-long injection borehole at a depth of 410 m. To extract and characterize massive, induced, high-frequency acoustic emission (AE) activity from continuous recordings, a semi-automated workflow was developed relying on full waveform based detection, classification and location procedures. The approach extended the AE catalogue from 196 triggered events in previous studies to more than 19 600 located AEs. The enhanced catalogue, for the first time, allows a detailed analysis of induced seismicity during single hydraulic fracturing experiments, including the individual fracturing stages and the comparison between injection schemes. Beside the detailed study of the spatio-temporal patterns, event clusters and the growth of seismic clouds, we estimate relative magnitudes and b-values of AEs for conventional, cyclic progressive and dynamic pulse injection schemes, the latter two being fatigue hydraulic fracturing techniques. While the conventional fracturing leads to AE patterns clustered in planar regions, indicating the generation of a single main fracture plane, the cyclic progressive injection scheme results in a more diffuse, cloud-like AE distribution, indicating the activation of a more complex fracture network. For a given amount of hydraulic energy (pressure multiplied by injected volume) pumped into the system, the cyclic progressive scheme is characterized by a lower rate of seismicity, lower maximum magnitudes and significantly larger b-values, implying an increased number of small events relative to the large ones. To our knowledge, this is the first direct comparison of high resolution seismicity in a mine-scale experiment induced by different hydraulic fracturing schemes.

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Journal articles on the topic 'Hydraulic activation'

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