Artículos de revistas sobre el tema "Stabilite tension"
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Kuang, Jianxun, Guodong Chen, Zhoulong Yuan, Xiajun Qi, Qianhao Yu y Zhen Liu. "Dynamic Interactions of a Cable-Laying Vessel with a Submarine Cable during Its Landing Process". Journal of Marine Science and Engineering 10, n.º 6 (3 de junio de 2022): 774. http://dx.doi.org/10.3390/jmse10060774.
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The rapid development of offshore electricity grid construction has led to a great demand for submarine cable deployment. In this study, a numerical model is established based on the commercial software ANSYS-AQWA to investigate the dynamic interactions between a cable-laying vessel and a submarine cable during its landing process, which has not yet been reported and is critical to the safety of the cable. The numerical model was validated by an experimental test on the mooring stability of a vessel conducted in a wave tank. The effects of the cable length, the current velocity, the incident wave, and the wind direction on vessel stability and the tensions in the mooring lines and cable were investigated. When the cable length is short, the submarine cable acts as a mooring cable that can stabilize the hull, but it is not safe to apply force to the submarine cable. At the same time, an increase in the current speed also increases the tensile force of the submarine cable. The influence of different incident wave directions and wind directions on the stability and tension of ships in mooring lines and cables was studied, and the most unfavorable environmental conditions for submarine cable laying were determined under different environmental conditions.
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Liu, Peng, Yuanying Qiu, Yu Su y Jiantao Chang. "On the Minimum Cable Tensions for the Cable-Based Parallel Robots". Journal of Applied Mathematics 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/350492.
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This paper investigates the minimum cable tension distributions in the workspace for cable-based parallel robots to find out more information on the stability. First, the kinematic model of a cable-based parallel robot is derived based on the wrench matrix. Then, a noniterative polynomial-based optimization algorithm with the proper optimal objective function is presented based on the convex optimization theory, in which the minimum cable tension at any pose is determined. Additionally, three performance indices are proposed to show the distributions of the minimum cable tensions in a specified region of the workspace. An important thing is that the three performance indices can be used to evaluate the stability of the cable-based parallel robots. Furthermore, a new workspace, the Specified Minimum Cable Tension Workspace (SMCTW), is introduced, within which all the minimum tensions exceed a specified value, therefore meeting the specified stability requirement. Finally, a camera robot parallel driven by four cables for aerial panoramic photographing is selected to illustrate the distributions of the minimum cable tensions in the workspace and the relationship between the three performance indices and the stability.
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Liu, Peng, Haibo Tian y Xinzhou Qiao. "Minimum Cable Tensions and Tension Sensitivity for Long-Span Cable-Driven Camera Robots with Applications to Stability Analysis". Actuators 12, n.º 1 (31 de diciembre de 2022): 17. http://dx.doi.org/10.3390/act12010017.
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Employing cables with strong flexibility and unidirectional restraints to operate a camera platform leads to stability issues for a camera robot with long-span cables considering the cable mass. Cable tensions, which are the constraints for the camera platform, have a critical influence on the stability of the robot. Consequently, this paper focuses on two special problems of minimum cable tension distributions (MCTDs) within the workspace and the cable tension sensitivity analysis (CTSA) for a camera robot by taking the cable mass into account, which can be used to investigate the stability of the robot. Firstly, three minimum cable tension distribution indices (MCTDIs) were proposed for the camera robot. An important matter is that the three proposed MCTDIs, which represent the weakest constraints for the camera platform, can be employed for investigating the stability of the robot. In addition, a specified minimum cable tension workspace (SMCTW) is introduced, where the minimum cable tension when the camera platform is located at arbitrary position meets the given requirement. Secondly, the CTSA model and cable tension sensitivity analysis index (CTSAI) for the camera robot were proposed with grey relational analysis method, in which the influence mechanism and influence degree of the positions of the camera platform relative to cable tensions was investigated in detail. Lastly, the reasonableness of the presented MCTDIs and the method for the CTSA with applications in the stability analysis of the camera robot were supported by performing some simulation studies.
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Shuaiquan, Zhao, Chang Yuping, Yang Yadie, Zhang Minglonghai, Hasan Kamrul y Hu Hong. "Auxetic behavior of warp knitted fabric under repeating tension". Textile Research Journal 91, n.º 15-16 (25 de enero de 2021): 1732–41. http://dx.doi.org/10.1177/0040517521989277.
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In our previous study, a novel class of auxetic warp knitted fabrics were developed and their auxetic behaviors were studied under a single tensile test. However, during daily use, the fabrics are usually subjected to repeating tension rather than single tension. Therefore, the durability of the fabrics’ auxetic performance is of great importance. So far, the auxetic behavior of fabrics under repeating tension has not systematically been investigated. In this paper, we report a study on the auxetic behavior of warp knitted fabrics under repeating tension. All the fabric samples were subjected to a repeating tensile test within a tensile strain of 25% until 100 tensile cycles. The results show that the fabrics can keep their auxetic effect in both course and wale testing directions after 100 tensile cycles, and the auxetic effect in the wale direction is retained longer under higher tensile strains than that under lower tensile strains with the increase of tensile cycles. The results also indicate that auxetic stability in the course direction is much better than that in the wale direction. We hope that this study can offer useful information to improve the auxetic stability of auxetic fabrics for practical use.
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Igwe, Charles Arizechukwu, Hermansah, Martin Eze Obi y Toshiyuki Wakatsuki. "Using Selected Structural Indices to Pinpoint the Field Moisture Capacity of Some Coarse-Textured Agricultural Soils in Southeastern Nigeria". Journal of Tropical Soils 16, n.º 2 (9 de julio de 2013): 151–59. http://dx.doi.org/10.5400/jts.2011.v16i2.151-159.
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Over- or underestimation of field capacity (FC) of agricultural soils could misguide soil and water management and this might have negative agronomic and environmental impacts. The study sought to identify the moisture tension for reliably estimating in the laboratory the FC of some sandy soils with low-activity clay minerals and at different levels of structure development in Nsukka agroecological zone in southeastern Nigeria. Fifty-four samples of topand subsoils under contrasting vegetation cover at three locations in the zone were analyzed for texture, organicmatter contents, bulk density and total porosity. Saturated hydraulic conductivities (Ksat) of the samples were equallydetermined. Water-conducting and water-filled porosities at each of 0.06-, 0.10- and 0.33-bar tensions were implied from water retention data at the respective tensions. The soils were categorized based on their levels of structure development using a structural stability index [(organic matter: silt+clay) %] as follows: very low (< 4%), low (4-7.5%) and moderate to high (> 7.5%) stability soils. Series of simple correlation tests were run among the waterconducting porosities at the various tensions and the Ksat of the soils. In each case, the soil was assumed to have attained FC at that moisture tension which the associated water-conducting porosity showed significant positive correlation with the Ksat. Our results revealed that the 0.06-bar tension overestimated the FC of the soils. The 0.10-bar tension, the commonly used moisture tension for the purpose in the study area, proved suitable only for soils within the moderate to high structural stability category. From all indications, the 0.33-bar tension best corresponded to the FC of the less structurally developed soils in the other two categories. The level of soil structure development should therefore be considered before deciding the suitable moisture tension for the determination of FC of these and similar soils in other tropical locations.Keywords: Coarse mineral soils, field moisture capacity, saturated hydraulic conductivity, structural stability,water-conducting pores
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REES, S. J. y M. P. JUNIPER. "The effect of surface tension on the stability of unconfined and confined planar jets and wakes". Journal of Fluid Mechanics 633 (25 de agosto de 2009): 71–97. http://dx.doi.org/10.1017/s0022112009007186.
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In this theoretical study, a linear spatio-temporal analysis is performed on unconfined and confined inviscid jet/wake flows with surface tension in order to determine convective/absolute instability criteria. There is a single mode that is due to surface tension and many modes that are due to the jet/wake column. In the unconfined case, the full impulse response is considered in the entire outer flow. On the one hand, the surface tension mode propagates slowly in the cross-stream direction but dominates at the front and back of the wavepacket. On the other hand, the jet/wake column modes propagate more quickly in the cross-stream direction and therefore define the boundaries of the central region of the wavepacket. The flow is particularly unstable when these modes interact. For unconfined flows, it is found that at low and intermediate surface tensions the flow can be more absolutely unstable than that without surface tension but at high surface tensions the flow is stabilized. The effect of confinement has previously been studied but not with the inclusion of surface tension. Confinement and surface tension combined cause the transition from convective to absolute instability to occur even with significant coflow. This effect is examined over an infinite domain of density ratios and confinement.
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Wei, Naying, Zhen Zhang, Xu Xu y Wenjuan Yao. "Stability Analysis of a TLP with Inclined Tension Legs under Different Marine Survival Conditions". Journal of Marine Science and Engineering 10, n.º 8 (31 de julio de 2022): 1058. http://dx.doi.org/10.3390/jmse10081058.
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To verify that inclined tension legs can improve the stability of the tension leg platform, this paper established the dynamic equation of a tension leg platform (TLP) under marine environmental loads by using the modified Morrison equation considering the influence of ocean currents on wave forces. Additionally, the velocity and acceleration of random wave water particles were simulated via the JONSWAP spectrum. In addition, a three-dimensional model of a tension leg platform with inclined tension legs was established by AQWA, and its dynamic responses under variable survival conditions were compared and analyzed. The results showed that the surge and heave were more sensitive to the sea current, while the pitch was more sensitive to the wind. There is a significant difference in tendon tensions between the atypical TLP with inclined tension legs established in this study and the typical International Ship and Offshore Structures Committee (ISSC) TLP.
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Yakupov, R. G. y D. M. Zaripov. "Seismic stability of the underground main pipeline". Proceedings of the Mavlyutov Institute of Mechanics 8, n.º 1 (2011): 275–86. http://dx.doi.org/10.21662/uim2011.1.027.
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The stress-deformed state of the underground main pipeline under the action of seismic waves of an earthquake is considered. The generalized functions of seismic impulses are constructed. The pipeline motion equations are solved with used Laplace transformation by the time. Tensions and deformations of the pipeline have been determined. A numerical example is reviewed. Diagrams of change of the tension depending on earthquake force are provided in earthquake-points.
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Liu, Peng, Haibo Tian, Xiangang Cao, Xuhui Zhang, Xinzhou Qiao y Yu Su. "Dynamic Stability Measurement and Grey Relational Stability Sensitivity Analysis Methods for High-Speed Long-Span 4-1 Cable Robots". Mathematics 10, n.º 24 (8 de diciembre de 2022): 4653. http://dx.doi.org/10.3390/math10244653.
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High-speed long-span 4-1 cable robots (4-1HSLSCRs) have the characteristics of a simple structure, superior performance and easy control, and they can be used comprehensively in coal quality sampling, water quality monitoring, aerial panoramic photographing, etc. However, because of the high-speed movement of the end-effector and the unidirectional constraint property and nonlinear characteristics of the long-span cables, the dynamic stability of the 4-1HSLSCRs presents severe challenges. This paper, as a result, focuses on the two special problems of carrying out dynamic stability measurement and a stability sensitivity analysis for the 4-1HSLSCRs. First, a systematic approach that combines the cable tension, position and velocity of the end-platform based on both the dynamic model and the determinations of the cable tension is proposed for the high-speed robot, in which two cable tension and two position influencing factors are developed, respectively, whereas a velocity function is constructed, which represents the influence of the end-effector velocity on the dynamic stability of the 4-1HSLSCRs. Second, a grey relational analysis method for analyzing the dynamic stability of the 4-1HSLSCRs is developed, where the relationship between the dynamic stability of the 4-1HSLSCRs and the influencing factors (the position and velocity of the end-effector, as well as the cable tension) is investigated in detail. Finally, the measure approach and sensitivity analysis method for dynamic stability of 4-1HSLSCRs, namely, a camera robot with a high speed and long-span cables, is verified through simulation results. The results show that the large-span cable sags have significant effects on both the cable tensions and the dynamic stability of the camera robot, whereas the stability sensitivity evaluation results indicate that the effect of the stability sensitivity of the cable tensions on the dynamic stability of the camera robot is the greatest, followed by the velocity of the end-effector, and last is the position of the end-effector.
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Howard, Anthony, Paul Harwood, Alice Benton, Charlotte Merrel, Peter Culmer, William Bolton y Todd Stewart. "AN IN VITRO STUDY EXAMINING WIRE TENSION IN FINE WIRE CIRCULAR EXTERNAL FIXATION CONSTRUCTS". Orthopaedic Proceedings 106-B, SUPP_5 (23 de abril de 2024): 27. http://dx.doi.org/10.1302/1358-992x.2024.5.027.
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IntroductionIlizarov fixators are reliant on tensioned fine wires for stability. The tension in the wires is generated using specific tensioning devices. Loss of wire tension over time may lead of loss a stability and complications. A series of in vitro experiments were undertaken to explore wire tensioner accuracy, the impact of fixation bolt torque and initial tension on loss of tension in ilizarov constructs under static and dynamic loads.Materials & MethodsMedical grade materials were applied to a synthetic bone analogue using surgical instruments in all experiments. Bolt torque was fixed at 6, 10 or 14 Nm using a torque limiting wrench. Wire tension was assessed using a strain measurement bridge. Wires were tensioned to 90, 110 and 130kg as measured by a commercial dynamometric tensioner. Static and dynamic testing was undertaken using an instron testing machine. Cyclical loads from 50–750N were applied for 5000 cycles.ResultsActual wire tension was approximately 15% less than indicated by the tensioner device. Using fixation bolt torques of 10Nm and 14Nm achieved final wire tensions of around 60% and 80% of that applied at 90 and 130kg of applied tension. Static load testing demonstrated self stiffening to similar levels in all pre-tensions. Dynamic testing demonstrated significant loss of tension, most of which occured in the first 3 cycles, inversely proportional to the tension initially applied.ConclusionsThese experiments provides insight into the effect of initially applied wire tension on Illizarov mechanical performance. It is important surgeons understand how the different ways that these devices are applied affects mechanical performance. Further research examining what factors affect performance across different manufacturers equipment would therefore be relevant, alongside the development of novel fixation methods to reduce wire slippage and the further development of equipment for clinical use.
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Liu, Peng, Xinzhou Qiao y Xuhui Zhang. "Stability sensitivity for a cable-based coal–gangue picking robot based on grey relational analysis". International Journal of Advanced Robotic Systems 18, n.º 6 (1 de noviembre de 2021): 172988142110597. http://dx.doi.org/10.1177/17298814211059729.
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This article aims to establish the relationship between the position and cable tension influencing factors and the stability, and propose a method for quantitative stability sensitivity assessment for a cable-based coal–gangue picking robot. Firstly, a structural stability measure approach is proposed for the cable-based coal–gangue picking robot. Secondly, a stability sensitivity analysis model is developed to investigate the stability sensitivity on the selected influencing factors based on the grey relational degree, where the influencing degree of each factor on the stability for the cable-based coal–gangue picking robot is explored with grey relational analysis. At last, a numerical study is carried out to demonstrate the stability measure approach and stability sensitivity analysis model for the cable-based coal–gangue picking robot was scientific and reasonable, where the end-grab position set which the robot can meet the predetermined stability requirements is obtained. And meanwhile, the correlation of each influencing factor on the stability for the robot is calculated. And the stability sensitivity simulation results show that (1) the correlation of the seven influencing factors on the stability are, in a descending order, cable tension T 2 > cable tension T 4 > cable tension T 3 > cable tension T 1 > z-direction displacement of the end-grab > x-direction displacement > y-direction displacement; (2) among the influencing factors, the cable tensions have greater influence on the stability of coal–gangue picking robot, and it is followed by the z-direction displacement of the end-grab, while y-direction displacement is found to have the minimal influence. This article provides a guiding direction for robust design of the sorting trajectory planning and control of the coal–gangue picking robots.
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JASH, Amrita. "Managing Tensions in the East China Sea: What Can China and Japan Do?" East Asian Policy 09, n.º 02 (abril de 2017): 54–60. http://dx.doi.org/10.1142/s1793930517000162.
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The growing tension between China and Japan over territoriality and maritime rights in the East China Sea has become one of the biggest potential flashpoints in the bilateral relationship. In no time, the disputed Diaoyu/Senkaku islands have become a great concern for the stability in China-Japan relations. Given the escalating tensions, managing this dispute has become imperative for maintaining bilateral as well as regional peace and stability. .
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Li, Bing, Fei Zhang y Di Wang. "Impact of Crack on Stability of Slope with Linearly Increasing Undrained Strength". Mathematical Problems in Engineering 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/1096513.
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This paper presents a procedure for assessment of the impact of tension crack on stability of slope in clays with linearly increasing undrained strength. The procedure is based on the limit equilibrium method with variational extremization. The distribution of the normal stress over slip surface is mathematically obtained for slopes in clays with the linearly increasing undrained strength and then used to determine the tension crack for clays with zero tensile strength. The seismic effect is also included using the pseudostatic approach. Closed-form solutions to the minimum safety factor and the maximum crack depth can be derived and given in the form of chart for convenient use. The results demonstrate a significant effect of the tension crack on the stability of steep slopes, especially for strong seismic conditions. In this situation, neglecting the impact of tension crack in traditional ϕ=0 analyses may overestimate the slope safety. The most adverse location of the tension crack can be also determined and presented in the charts, which may be useful in designing reinforcements and remedial measures for slope stabilization.
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Schurch, S., D. Schurch, T. Curstedt y B. Robertson. "Surface activity of lipid extract surfactant in relation to film area compression and collapse". Journal of Applied Physiology 77, n.º 2 (1 de agosto de 1994): 974–86. http://dx.doi.org/10.1152/jappl.1994.77.2.974.
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The physical properties of modified porcine surfactant (Curosurf), isolated from minced lungs by extraction with chloroform-methanol and further purified by liquid-gel chromatography, were investigated with the captive bubble technique. Bubble size, and thus the surface tension of an insoluble film at the bubble surface, is altered by changing the pressure within the closed bubble chamber. The film surface tension and area are determined from the shape (height and diameter) of the bubble. Adsorption of fresh Curosurf is characterized by stepwise decreases in surface tension, which can easily be observed by sudden quick movements of the bubble apex. These “adsorption clicks” imply a cooperative movement of large collective units of molecules, approximately 10(14) (corresponding to approximately 120 ng of phospholipid) or approximately 10(18) molecules/m2, into the interface during adsorption. Films formed in this manner are already highly enriched in dipalmitoyl phosphatidylcholine, as seen by the extremely low compressibility, close to that of dipalmitoyl phosphatidylcholine. Near-zero minimum tensions are obtained, even at phospholipid concentrations as low as 50 micrograms/ml. During dynamic cycling (20–50 cycles/min), low minimum surface tensions, good film stability, low compressibility, and maximum surface tensions between 30 and 40 mN/m are possible only if the films are not overcompressed near zero surface tension; i.e., the overall film area compression should not substantially exceed 30%.
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Samuel Olalekan Olusanya, Samuel Olalekan Olusanya, Gbenga Joseph Adebayo Gbenga Joseph Adebayo y Samuel Olutayo Afolabi and Adewumi Oluwasogo Dada Samuel Olutayo Afolabi and Adewumi Oluwasogo Dada. "Effect of Salt on the Stability of Vegetable Oil-in-Water Emulsions Stabilized by Soybean Protein and Microgel". Journal of the chemical society of pakistan 43, n.º 5 (2021): 520. http://dx.doi.org/10.52568/000604/jcsp/43.05.2021.
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The preparation of vegetable oil-water emulsions stabilized by soybean protein and microgel is described. The soybean protein was obtained from n-hexane-defatted soybean powder using a Soxhlet extractor. Using equal volumes of oil and water, vegetable oil-water emulsions were formed either by handshaking the mixture or homogenizing the mixture using a Lab homogenizer. The emulsion was characterized using a drop test and microscopy observation. The drop test shows that the preferred emulsion is vegetable oil-in-water (o/w). The effect of salt and emulsifier concentration on the stability and emulsion drop size was investigated. Emulsions stabilized by soybean protein without addition of salt breakdown after 3 days of preparation because of decomposition of the protein. For emulsions stabilized by microgel in the absence of salt, phase separation occurred within 1 hour. At a fixed salt concentration, it was found that increasing the emulsifier concentration has a significant effect on the stability and drop size of the emulsions stabilized by both protein and microgel. For emulsions stabilized by soybean protein, the stability of emulsions increased with increasing salt concentration without any significant influence on the drop size. The results obtained from the surface tension measurement revealed that different mechanisms of stabilization exist in emulsions stabilized by the protein and microgel.
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Samuel Olalekan Olusanya, Samuel Olalekan Olusanya, Gbenga Joseph Adebayo Gbenga Joseph Adebayo y Samuel Olutayo Afolabi and Adewumi Oluwasogo Dada Samuel Olutayo Afolabi and Adewumi Oluwasogo Dada. "Effect of Salt on the Stability of Vegetable Oil-in-Water Emulsions Stabilized by Soybean Protein and Microgel". Journal of the chemical society of pakistan 43, n.º 5 (2021): 520. http://dx.doi.org/10.52568/000604.
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The preparation of vegetable oil-water emulsions stabilized by soybean protein and microgel is described. The soybean protein was obtained from n-hexane-defatted soybean powder using a Soxhlet extractor. Using equal volumes of oil and water, vegetable oil-water emulsions were formed either by handshaking the mixture or homogenizing the mixture using a Lab homogenizer. The emulsion was characterized using a drop test and microscopy observation. The drop test shows that the preferred emulsion is vegetable oil-in-water (o/w). The effect of salt and emulsifier concentration on the stability and emulsion drop size was investigated. Emulsions stabilized by soybean protein without addition of salt breakdown after 3 days of preparation because of decomposition of the protein. For emulsions stabilized by microgel in the absence of salt, phase separation occurred within 1 hour. At a fixed salt concentration, it was found that increasing the emulsifier concentration has a significant effect on the stability and drop size of the emulsions stabilized by both protein and microgel. For emulsions stabilized by soybean protein, the stability of emulsions increased with increasing salt concentration without any significant influence on the drop size. The results obtained from the surface tension measurement revealed that different mechanisms of stabilization exist in emulsions stabilized by the protein and microgel.
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Lv, Guangdong, Yi He y Bingsi Wei. "Dynamic Stability Analysis of Slope Subjected to Surcharge Load considering Tensile Strength Cut-Off". Mathematical Problems in Engineering 2020 (12 de octubre de 2020): 1–17. http://dx.doi.org/10.1155/2020/5196303.
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Surcharge slopes are more vulnerable to instability under the effects of earthquake ground shaking, especially considering the tensile stress. In order to account for the adverse factors of seismic forces and tensile stress, the theory of soil with tensile strength cut-off is deduced and analyzed using the upper bound limit analysis method in this paper. Combined with the quasistatic analysis, the equation of critical acceleration expression for surcharge slope subjected to the dynamic conditions has been evaluated. By using the improved Newmark method, permanent displacements have been analyzed in the case of the classical earthquake ground motions. In addition, optimization algorithm has been undertaken, in which several influencing factors such as slope inclination, internal friction angle, surcharge factor, seismic load, and tension cut-off coefficient have been taken into account, and some results are verified with the classical solutions and FEM results. The results concluded the following: (1) The outcomes of verification results are accurate. (2) The critical acceleration of the slope is significantly affected by tension cut-off with the increasing of surcharge factor and seismic effects. (3) The permanent displacements of surcharge slope considering the tensile strength cut-off can be even 2 times of the traditional analysis; meanwhile, with more reduction of tensile strength, the cumulative displacements increase rapidly. Therefore, considering the influence of tensile strength cut-off is fundamental to the dynamic stability design of surcharge conditions.
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Gu, Jin-Ben, Jun-Yan Wang y Yi-Qing Guo. "Cyclic Behavior of Reinforced High Strain-Hardening UHPC under Axial Tension". Materials 14, n.º 13 (28 de junio de 2021): 3602. http://dx.doi.org/10.3390/ma14133602.
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The cyclic tensile behavior of steel-reinforced high strain-hardening ultrahigh-performance concrete (HSHUHPC) was investigated in this paper. In the experimental program, 12 HSHUHPC specimens concentrically placed in a single steel reinforcement under cyclic uniaxial tension were tested, accompanied by acoustic emission (AE) source locating technology, and 4 identical specimens under monotonic uniaxial tension were tested as references. The experimental variables mainly include the loading pattern, the diameter of the embedded steel rebar, and the level of target strain at each cycle. The tensile responses of the steel-reinforced HSHUHPC specimens were evaluated using multiple performance measures, including the failure pattern, load–strain response, residual strain, stiffness degradation, and the tension-stiffening behavior. The test results showed that the enhanced bond strength due to the inclusion of steel fibers transformed the failure pattern of the steel-reinforced HSHUHPC into a single, localized macro-crack in conjunction with a sprinkling of narrow and closely spaced micro-cracks, which intensified the strain concentration in the embedded steel rebar. Besides, it was observed that the larger the diameter of the embedded steel rebar, the smaller the maximum accumulative tensile strain under cyclic tension, which indicated that the larger the diameter of the embedded steel rebar, the greater the contribution to the tensile stiffness of steel-reinforced HSHUHPC specimens in the elastic–plastic stage. In addition, it was found that a larger embedded steel rebar appeared to reduce the tension-stiffening effect (peak tensile strength) of the HSHUHPC. Moreover, the residual strain and the stiffness of the steel-reinforced HSHUHPC were reduced by increasing the number of cycles and finally tended toward stability. Nevertheless, different target strain rates in each cycle resulted in different eventual cumulative tensile strain rates; hence the rules about failure pattern, residual strain, and loading stiffness were divergent. Finally, the relationship between the accumulative tensile strain and the loading stiffness degradation ratio under cyclic tension was proposed and the tension-stiffening effect was analyzed.
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Qin, Zhen, Yuting Wu, Jianchen Cong y Sung-Ki Lyu. "Mechanism Design and Experimental Verification of Novel Automatic Balance Equipment for a Rope-Type Elevator". Machines 10, n.º 12 (7 de diciembre de 2022): 1180. http://dx.doi.org/10.3390/machines10121180.
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Multi-rope elevators are widely used in modern buildings. However, problems such as vibration, noise, uneven wear of key components and shortened life caused by the uneven distribution of rope tensions are still unsolved in the elevator industry. In order to balance the different tensions and the axial deformation of each rope, a novel automatic balance equipment for rope-type elevators (NABE-RE) is proposed in this article. Simulations based on the Simscape numerical methodology are used to verify the kinematic rationality of the proposed mechanism. The optimal structural stability of the core components is evaluated through a series of investigations based on the finite element method. Additionally, the manufactured prototypes are put through a series of comparison experiments to evaluate their tension balancing performance. The results show that the unbalance rate of the system is effectively limited to a low level, thus verifying the feasibility of the automatic tension balancing function of the proposed NABE-RE.
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Peng, Tiefeng, Siyuan Yang, Fan Xiang, Yunpei Liang, Qibin Li, Xuechao Gao y Sanjun Liu. "Film tension of liquid nano-film from molecular modeling". International Journal of Modern Physics B 31, n.º 04 (6 de febrero de 2017): 1750016. http://dx.doi.org/10.1142/s0217979217500163.
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Due to its geometry simplicity, the forces of thin liquid film are widely investigated and equivalently employed to explore the phys–chemical properties and mechanical stability of many other surfaces or colloid ensembles. The surface tension of bulk liquid ([Formula: see text]) and film tension ([Formula: see text]) are the most important parameters. Considering the insufficiency of detailed interpretation of film tension under micro-scale circumstances, a method for film tension was proposed based on numerical modeling. Assuming surface tension at different slab thicknesses being identical to the surface tension of film, the surface tension and disjoining pressure were subsequently used to evaluate the film tension based on the derivation of film thermodynamics, and a decreasing tendency was discovered for low temperature regions. The influence of saline concentration on nano-films was also investigated, and the comparison of film tensions suggested that higher concentration yielded larger film tension, with stronger decreasing intensity as a function of film thickness. Meanwhile, at thick film range (15–20 nm), film tension of higher concentration film continued to decrease as thickness increase, however it arrived to constant value for that of lower concentration. Finally, it was found that the film tension was almost independent on the film curvature, but varied with the thickness. The approach is applicable to symmetric emulsion films containing surfactants and bi-layer lipid films.
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Wolf, C. "The stability of tension stars". Astronomische Nachrichten: A Journal on all Fields of Astronomy 314, n.º 6 (1993): 413–16. http://dx.doi.org/10.1002/asna.2113140606.
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Wu, Hao, Tianshu Zhang, Xiaochen Lai, Haixia Yu, Dachao Li, Hao Zheng, Hui Chen, Claus-Dieter Ohl y Yuanyuan Li. "Influence of Surface Tension on Dynamic Characteristics of Single Bubble in Free-Field Exposed to Ultrasound". Micromachines 13, n.º 5 (17 de mayo de 2022): 782. http://dx.doi.org/10.3390/mi13050782.
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The motion of bubbles in an ultrasonic field is a fundamental physical mechanism in most applications of acoustic cavitation. In these applications, surface-active solutes, which could lower the surface tension of the liquid, are always utilized to improve efficiency by reducing the cavitation threshold. This paper examines the influence of liquids’ surface tension on single micro-bubbles motion in an ultrasonic field. A novel experimental system based on high-speed photography has been designed to investigate the temporary evolution of a single bubble in the free-field exposed to a 20.43 kHz ultrasound in liquids with different surface tensions. In addition, the R-P equations in the liquid with different surface tension are solved. It is found that the influences of the surface tension on the bubble dynamics are obvious, which reflect on the changes in the maximum size and speed of the bubble margin during bubble oscillating, as well as the weaker stability of the bubble in the liquid with low surface tension, especially for the oscillating bubble with higher speed. These effects of the surface tension on the bubble dynamics can explain the mechanism of surfactants for promoting acoustic cavitation in numerous application fields.
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Zhang, Tan, Songtao Lin, Hong Zheng y Dianjie Zhang. "Location of Tension Cracks at Slope Crests in Stability Analysis of Slopes". Geotechnics 2, n.º 3 (21 de junio de 2022): 488–505. http://dx.doi.org/10.3390/geotechnics2030024.
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Over the conventional limit equilibrium method and limit analysis method, the finite element method is advantageous, especially for slopes involving complex failure mechanisms where the critical slip surfaces cannot be represented by log spirals and other similarities. In the presence of tension cracks at slope crests, however, the finite element method encounters difficulties in convergence while handling Mohr–Coulomb’s yielding surfaces with tensile strength cut-off. Meanwhile, the commonly used load-controlled method for the system of nonlinear equilibrium equations is hard to bring the slope into the limit equilibrium state. The two drawbacks drag down the finite element method in more extensive applications. By reducing the constitutive integration of plasticity with non-smooth yielding surfaces to the mixed complementarity problem, the convergence in numerical constitutive integration is established for arbitrarily large incremental strains. In order to bring the slope to the limit equilibrium state, a new displacement-controlled algorithm is designed for the system of nonlinear equilibrium equations, which is far more efficient than the load-controlled method. A procedure is proposed to locate tension cracks. Corresponding to the Mohr–Coulomb failure criterion with and without tensile strength cut-off, the failure mechanisms differ significantly, while the difference in the factor of safety might be ignorable.
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Lukasenoks, Arturs, Rolands Cepuritis y Andrejs Krasnikovs. "Effect of the Fibre Type on the Rheological and Mechanical Properties of Cementitious Composites for Thin Overlays". Key Engineering Materials 762 (febrero de 2018): 362–67. http://dx.doi.org/10.4028/www.scientific.net/kem.762.362.
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Polypropylene (PP), nylon and polyvinyl alcohol (PVA) micro-fibres with different geometries were used at 1 vol. % dosage to investigate rheological and mechanical properties of cementitious composites to be used for thin overlays. Slump-flow and visual stability index methods were used to characterise the rheological properties. Single crack tension and bending studies were carried out to evaluate the tensile and bending strength, as well as the post-cracking behaviour. The results show that fibre geometry (L/d ratio and specific surface area) has a pronounced influence on the fresh state rheological properties of the cementitious composites. The results also surprisingly indicated that the nylon fibres are able to significantly increase the pre-cracking tensile and bending strength. All tested composites showed tensile strain softening and insignificant deflection hardening after cracking and a major strength loss. The results indicate single crack tension method to be the most appropriate for evaluation of mechanical properties of cementitious composites used for thin overlays.
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Flores, Tatiana, Alejandra Rojas-Graü, Juan Ignacio Maté y Jesús Esparza. "Strategies to Reduce Purge Losses in Meat Products Stuffed in Plastic Casings". Journal of Food Quality 2023 (15 de marzo de 2023): 1–10. http://dx.doi.org/10.1155/2023/8536199.
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Two different meat emulsions were prepared with different physical stability: R1 with 6.28 ± 1.13% total expressible fluid and R2 with 17.7 ± 1.48%. The emulsions were placed in plastic casings at three different surface tensions (ST), expressed as contact angle, and three distinct overstuffing percentages (OS). The stuffed samples were cooked in an industrial oven. After cooling, purge losses (PL) and texture profile analysis (TPA) were measured. The reduced surface tension of the plastic casings significantly decreased the PL of both recipes. In the case of R2, a combination of high OS and low ST was necessary to reduce PL in a 60%. In the case of TPA, OS had a statistical influence on parameters like chewiness, cohesiveness, and hardness. Plastic casings with different surface tension (to increase adherence of meat emulsion to the casing) stuffed at different levels of overstuffing percentages (to reduce free space between meat emulsion and casing) represent a potential tool to reduce PL of products based on low stability meat emulsions.
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Yang, Yi y Dong Xiang. "Effect of Coconut Protein and Xanthan Gum, Soybean Polysaccharide and Gelatin Interactions in Oil-Water Interface". Molecules 27, n.º 9 (30 de abril de 2022): 2879. http://dx.doi.org/10.3390/molecules27092879.
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We report on our study of the interactions between coconut protein extracted from coconut meat and three hydrocolloids (gelatin, xanthan gum, and soybean polysaccharide) and their interfacial adsorption and emulsification properties. We used Zeta potential, fluorescence spectroscopy scanning and ITC to investigate the interactions between a fixed concentration (1%) of coconut protein and varying concentrations of hydrocolloid. Through the interfacial tension and interfacial viscoelasticity, the interfacial properties of the hydrocolloid and coconut protein composite solution were explored. The physical stability of the corresponding emulsion is predicted through microstructure and stability analysis. Xanthan gum forms a flocculent complex with coconut protein under acidic conditions. Soy polysaccharides specifically bind to coconut protein. Under acidic conditions, this complex is stabilized through the steric hindrance of soy polysaccharides. Due to gelatin-coconut protein interactions, the isoelectric point of this complex changes. The interfacial tension results show that as time increases, the interfacial tensions of the three composite solutions decrease. The increase in the concentration of xanthan gum makes the interfacial tension decrease first and then increase. The addition of soybean polysaccharides reduces the interfacial tension of coconut protein. The addition of xanthan gum forms a stronger elastic interface film. Emulsion characterization showed that the gelatin-added system showed better stability. However, the addition of xanthan gum caused stratification quickly, and the addition of soybean polysaccharides also led to instability because the addition of polysaccharides led to a decrease in thermodynamic compatibility. This research lays the foundation for future research into coconut milk production technology.
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Oggins, Jean. "Topics of Marital Disagreement among African-American and Euro-American Newlyweds". Psychological Reports 92, n.º 2 (abril de 2003): 419–25. http://dx.doi.org/10.2466/pr0.2003.92.2.419.
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To see what issues couples most and least often reported as topics of marital disagreement, survey data were analyzed for 113 African-American and 131 Euro-American couples reporting in the first and third years of marriage. Friedman tests showed that in both the first and third years of marriage, money was most often reported as a topic of marital disagreement; tensions about leisure, each spouse's family of origin, and children were reported significantly less often; and tensions about religion were reported least often. Findings were very similar for African Americans and Euro-Americans, and for husbands and wives. Overall, findings show considerable stability in the relative frequency with which specific topics reportedly evoke tension early in marriage.
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Lerdahl, Fred. "Calculating Tonal Tension". Music Perception 13, n.º 3 (1996): 319–63. http://dx.doi.org/10.2307/40286174.
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The prolongational component in A Generative Theory of Tonal Music assigns tensing and relaxing patterns to tonal sequences but does not adequately describe degrees of harmonic and melodic tension. This paper offers solutions to the problem, first by adapting the distance algorithm from the theory of tonal pitch space for the purpose of quantifying sequential and hierarchical harmonic tension. The method is illustrated for the beginning of the Mozart Sonata, K. 282, with emphasis on the hierarchical approach. The paper then turns to melodic tension in the context of the anchoring of dissonance. Interrelated attraction algorithms are proposed that incorporate the factors of stability, proximity, and directed motion. A distinction is developed between the tension of distance and the tension of attraction. The attraction and distance algorithms are combined in a view of harmony as voice leading, leading to a second analysis of the opening phrase of the Mozart in terms of voiceleading motion. Connections with recent theoretical and psychological work are discussed.
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Shu, Jiaming, Lishuai Jiang, Peng Kong y Qingbiao Wang. "Numerical Analysis of the Mechanical Behaviors of Various Jointed Rocks under Uniaxial Tension Loading". Applied Sciences 9, n.º 9 (1 de mayo de 2019): 1824. http://dx.doi.org/10.3390/app9091824.
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In a complex stress field of underground mining or geotechnical practice, tension damage/failure in rock masses is easily triggered and dominant. Unlike metals, rocks are generally bi-modularity materials with different mechanical properties (Young’s modulus, etc.) in compression and tension. It is well established that the Young’s modulus of a rock mass is directly related to the presence of the fracture or joint, and the Young’s modulus estimation for jointed rocks and rock masses is essential for stability analysis. In this paper, the tensile properties in joint rocks were investigated by using numerical simulations based on the discrete element method. Four influencing parameters relating to the tensile properties (joint dip angle, joint spacing, joint intersection angle, and joint density) were studied. The numerical results show that there is an approximately linear relationship between the joint dip angle (α) and the joint intersection angle (β) with the tensile strength (σt), however, the changes in α and β have less influence on the Young’s modulus in tension (Et). With respect to joint spacing, the simulations show that the effects of joint spacing on σt and Et are negligible. In relation to the joint density, the numerical results reveal that the joint intensity of rock mass has great effect on Et but insignificant effect on σt.
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Spišák, Emil y Janka Majerníková. "The Loss of Plasticity Stability". Applied Mechanics and Materials 693 (diciembre de 2014): 346–51. http://dx.doi.org/10.4028/www.scientific.net/amm.693.346.
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The real values of plastic properties of steel sheets are basic input parameters for objectification of deep drawing technological processes. The loss of stability of plastic properties is the criterion of evaluation of plastic properties of steel sheets in most cases. The loss of stability of plastic properties depends on stress-strain scheme in real conditions of deep drawing of sheets. In the contribution will be evaluated the loss of plastic properties stability of thin double reduced packaging sheets made from low carbon steels. For evaluation of strength and plastic properties of thin packaging sheets is the tensile test most used at present. The material is stressed by uniaxial tension during this test. In the conditions of technological processes of drawing, which thin packaging sheets are mostly treating, is this way of stress not very objective. In most cases it deals about multiaxial stress of sheet by deformation of sheet to require draw cup. At the present, the biggest problem of thin steel sheets by uniaxial tension test evaluation is the loss of plastic deformation stability (localization of plastic deformation). Therefore, obtained results of plastic deformation during this test do not correspond with real plastic properties of thin steel sheets. In the contribution, will be compared the evaluation of plastic properties of these sheets by uniaxial and biaxial load. Biaxial load is unfavourable from stress point, but less sensitive on loss stability of plastic deformation from conditions test influence point.
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Lewis, D. D., S. Rigaud, G. B. Mackinzie, A. J. Rapoff y A. R. Cross. "Effects of wire tension on the biomechanics of asymmetric four-ring circular external skeletal fixator constructs". Veterinary and Comparative Orthopaedics and Traumatology 15, n.º 01 (2002): 44–50. http://dx.doi.org/10.1055/s-0038-1632712.
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SummaryThis study evaluated the effects of fixation wire tension (0 kg, 30 kg, 60 kg, and 90 kg) on the biomechanics of a four ring asymmetric circular external fixator construct in four testing modes (axial compression, medio-lateral bending, craniocaudal bending, and torsional loading) using a gap fracture model. Wire tension had a significant direct effect on gap stiffness in all of the testing modes. Axial compression load-deformation curves exhibited non-linearity, characteristic of the self-tensioning effect observed with fine wire fixation. Bending loaddeformation curves had two discrete linear segments, attributable to slipping of the bone models on the fixation wires, once a critical bending moment was exceeded. Torsional loading caused a gradual ‘windup’ of the construct which was followed by a linear load-displacement curve. Increasing wire tension had a small but significant effect on gap stiffness, which generally diminished as higher tensions were applied, thus demonstrating the need for adequate initial construct design to achieve sufficient stability during fracture healing.
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Cao, Tian Dong y Xiao Ming Yang. "Study on Mechanical Properties at High Temperatures and Microstructure of Mg-12Gd-3Y-0.5Zr Magnesium Alloy". Advanced Materials Research 997 (agosto de 2014): 618–23. http://dx.doi.org/10.4028/www.scientific.net/amr.997.618.
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In this paper, tensile tests were carried out on the as-rolled and heat-treated Mg-12Gd-3Y-0.5Zr magnesium alloy at different temperatures. Tendency of tensile strength vs temperature was investigated and strengthening mechanism was discussed. It shows that both as-rolled and heat-treated Mg-12Gd-3Y-0.5Zr magnesium alloy have good mechanical properties at high temperatures. The reason why they have poor tension-compression asymmetry was discussed by their texture analysis. It is indicated that solution strengthening and precipitation strengthening were main strengthening mechanisam, and RE additons improve their thermal stability which lead to their high tensile strength at high temperatures.
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Cohen, Denis y Massimiliano Schwarz. "Tree-root control of shallow landslides". Earth Surface Dynamics 5, n.º 3 (17 de agosto de 2017): 451–77. http://dx.doi.org/10.5194/esurf-5-451-2017.
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Abstract. Tree roots have long been recognized to increase slope stability by reinforcing the strength of soils. Slope stability models usually include the effects of roots by adding an apparent cohesion to the soil to simulate root strength. No model includes the combined effects of root distribution heterogeneity, stress-strain behavior of root reinforcement, or root strength in compression. Recent field observations, however, indicate that shallow landslide triggering mechanisms are characterized by differential deformation that indicates localized activation of zones in tension, compression, and shear in the soil. Here we describe a new model for slope stability that specifically considers these effects. The model is a strain-step discrete element model that reproduces the self-organized redistribution of forces on a slope during rainfall-triggered shallow landslides. We use a conceptual sigmoidal-shaped hillslope with a clearing in its center to explore the effects of tree size, spacing, weak zones, maximum root-size diameter, and different root strength configurations. Simulation results indicate that tree roots can stabilize slopes that would otherwise fail without them and, in general, higher root density with higher root reinforcement results in a more stable slope. The variation in root stiffness with diameter can, in some cases, invert this relationship. Root tension provides more resistance to failure than root compression but roots with both tension and compression offer the best resistance to failure. Lateral (slope-parallel) tension can be important in cases when the magnitude of this force is comparable to the slope-perpendicular tensile force. In this case, lateral forces can bring to failure tree-covered areas with high root reinforcement. Slope failure occurs when downslope soil compression reaches the soil maximum strength. When this occurs depends on the amount of root tension upslope in both the slope-perpendicular and slope-parallel directions. Roots in tension can prevent failure by reducing soil compressive forces downslope. When root reinforcement is limited, a crack parallel to the slope forms near the top of the hillslope. Simulations with roots that fail across this crack always resulted in a landslide. Slopes that did not form a crack could either fail or remain stable, depending on root reinforcement. Tree spacing is important for the location of weak zones but tree location on the slope (with respect to where a crack opens) is as important. Finally, for the specific cases tested here, intermediate-sized roots (5 to 20 mm in diameter) appear to contribute most to root reinforcement. Our results show more complex behaviors than can be obtained with the traditional slope-uniform, apparent-cohesion approach. A full understanding of the mechanisms of shallow landslide triggering requires a complete re-evaluation of this traditional approach that cannot predict where and how forces are mobilized and distributed in roots and soils, and how these control shallow landslides shape, size, location, and timing.
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Mohd, T. A. T., Azwan Harun, Nurul Aimi Ghazali, N. Alias y Effah Yahya. "Interfacial Tension Dependence on Nanoparticle Surface Modification for Stabilization of CO2 Foam in EOR: An Overview". Advanced Materials Research 1113 (julio de 2015): 637–42. http://dx.doi.org/10.4028/www.scientific.net/amr.1113.637.
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Foam Flooding have been suggested to replace gas injection in Enhanced Oil Recovery (EOR) method since it will improve the volumetric sweep efficiency due to its low mobility. This paper aims to review on the relationship of Interfacial Tension (IFT) of the CO2foams and nanoparticle surface modification. Generally, in foam flooding technique, surfactant is used to stabilize the CO2foams. However, the concern about the stability of the surfactant-stabilized CO2foam has been rising due to high surfactant adsorption on the rock surface and they also tend to degrade at high temperature. Hence, nanoparticle has been introduced to generate more stable CO2foam by adsorption of nanoparticles at the fluid-fluid interface. Based on the review, the stability of CO2foam generated by nanoparticles is due to the strong adhesion energy at the fluid-fluid interface where the interfacial tension between aqueous phase and CO2gas phase inside the foam is one of the key parameter. It also has been identified that the main factors that influenced the interfacial tension at the fluid-fluid interface are the nanoparticles concentration and the degree of hydrophilicity of nanoparticles. The correct amount of nanosolid particles present at the fluid-fluid interface and the optimum degree of hydrophilicity with favorable contact angles less than 90 degree will increase the interfacial tension that lead to increase in adhesion energy and high stability foam can be generated.
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Mukhopadhyay, S. K., E. M. O. Bebbington y P. W. Foster. "Structural Morphology of High Speed Spun Polyester Fibers". Textile Research Journal 62, n.º 7 (julio de 1992): 403–5. http://dx.doi.org/10.1177/004051759206200707.
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Poly(ethylene terephthalate) monofilaments spun at speeds ranging from 4 to 9 km/min were studied using a flexible thermomechanical analyzer, Instron tensile tester, transmission electron microscopy, and differential scanning calorimetry. Dynamic shrinkage tension behavior, modulus and elongation, electron diffraction patterns of ultra thin cross sections of fibers, and the melting behavior of the materials are discussed in terms of structural stability, crystallinity, and crystalline orientation.
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Brady, P. R. "On the stability of tension stars". Monthly Notices of the Royal Astronomical Society 255, n.º 3 (1 de abril de 1992): 379–81. http://dx.doi.org/10.1093/mnras/255.3.379.
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Firouzi, Behnam, Khalid A. Alattas, Mohsen Bakouri, Abdullah K. Alanazi, Ardashir Mohammadzadeh, Saleh Mobayen y Afef Fekih. "A Type-2 Fuzzy Controller for Floating Tension-Leg Platforms in Wind Turbines". Energies 15, n.º 5 (24 de febrero de 2022): 1705. http://dx.doi.org/10.3390/en15051705.
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This paper proposes a type-2 fuzzy controller for floating tension-leg platforms in wind turbines. Its main objective is to stabilize and control offshore floating wind turbines exposed to oscillating motions. The proposed approach assumes that the dynamics of all units are completely unknown. The latter are approximated using the proposed Sugeno-based type-2 fuzzy approach. A nonlinear Kalman-based algorithm is developed for parameter optimization, and linear matrix inequalities are derived to analyze the system’s stability. For the fuzzy system, both rules and membership functions are optimized. Additionally, in the designed approach, the estimation error of the type-2 fuzzy approach is also considered in the stability analysis. The effectiveness and performance of the proposed approach is assessed using a simulation study of a tension leg platform subject to various disturbance modes.
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Shen, Rongxi, Hongru Li, Enyuan Wang, Dexing Li, Zhenhai Hou, Xuan Zhang y Xu Han. "Mechanical behavior and AE and EMR characteristics of natural and saturated coal samples in the indirect tensile process". Journal of Geophysics and Engineering 16, n.º 4 (11 de julio de 2019): 753–63. http://dx.doi.org/10.1093/jge/gxz045.
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Abstract The differences between mechanical properties and acoustic emission (AE) and electromagnetic radiation (EMR) characteristics of natural coal samples and saturated coal samples were analyzed by performing indirect tensile experiments. The experimental results show that coal samples go through four stages: compaction, elastic deformation, plastic deformation and failure. There is good correspondence between AE and EMR signals and the damage to coal samples. Under the action of water, tension strength of samples is reduced, while the plasticity is enhanced; also, the softening coefficient of tensile strength becomes 0.65. The saturated coal samples have a longer plastic stage and a more obvious AE quiet period. The damage to natural coal samples is tension damage, while that of saturated coal samples is due to tension and shear damage, which is more sufficient and irregular. EMR is still remarkable when AE is in a quiet period, and EMR is better for the precursor of rupture. Water weakens the generation and propagation of AE and EMR signals, especially in the earlier stage. AE and EMR damage factor D, defined by AE and EMR counts, has a better description of the damage degree in the indirect tensile process. This study is of great significance for research on the damage mechanism of water-bearing coal, the stability monitoring of water-bearing coals in the actual engineering process and the effect evaluation of hydraulic flushing.
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HAYASHI, Takeharu, Yoshinori EBIHARA, Hirohiko WATANABE y Tatsuhiko ASAI. "Attempt to Stability Improvement on FEA of Tensile Tests, Tension-Compression Tests and Stress Relaxation Tests". Journal of Smart Processing 4, n.º 4 (2015): 207–14. http://dx.doi.org/10.7791/jspmee.4.207.
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LIU, XING JUN, CUI PING WANG, JIAN ZHONG JIANG, IKUO OHNUMA, RYOSUKE KAINUMA y KIYOHITO ISHIDA. "THERMODYNAMIC CALCULATION OF PHASE DIAGRAM AND PHASE STABILITY WITH NANO-SIZE PARTICLES". International Journal of Modern Physics B 19, n.º 15n17 (10 de julio de 2005): 2645–50. http://dx.doi.org/10.1142/s0217979205031468.
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In the present paper, the surface tensions and interfacial energies for pure metals and alloys for different structures were predicted by combining with the evaluated thermodynamic parameters in the framework of the CALPHAD (Calculation of Phase Diagrams) method. It is shown that the calculated results are in good agreement with the existing experimental data. On the basis of the predicted values of surface tension and interfacial energy, the phase stability and phase diagram with nano-size particles can be calculated by considering the Gibbs-Thomson equation. The calculated results for pure Fe indicate that the fcc phase is more stable with the decreasing of size of particles, which is in agreement with the experimental data reported, and the phase diagram with nano-size particle can be calculated.
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Qiao, Ling y Ling Hui He. "Surface Stability of a Biaxially Pre-Tensioned Soft Elastic Film Interacting with a Contactor". Materials Science Forum 749 (marzo de 2013): 611–16. http://dx.doi.org/10.4028/www.scientific.net/msf.749.611.
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The elastic buckling of a biaxially pre-tensioned soft elastic film in proximity to a rigid contactor was studied. By a linear analysis, it was shown that the critical mode of buckling depended on the two in-plane principal stretches in the respective tensile directions, and the threshold of buckling only depended on the product of two principal stretches. Such a regular effect of pre-tension may be applied in the field of the generation of the precise surface patterns.
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Qanbar, R., S. Cheng, F. Possmayer y S. Schurch. "Role of the palmitoylation of surfactant-associated protein C in surfactant film formation and stability". American Journal of Physiology-Lung Cellular and Molecular Physiology 271, n.º 4 (1 de octubre de 1996): L572—L580. http://dx.doi.org/10.1152/ajplung.1996.271.4.l572.
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The effect of palmitoylation of pulmonary surfactant-associated protein C (SP-C) on the surface activity of phospholipid mixtures of dipalmitoylphosphatidylcholine and phosphatidylglycerol was studied. Phospholipids reconstituted with palmitoylated or depalmitoylated bovine SP-C were examined at neutral and acidic pH using a captive bubble surfactometer. At low pH, effective lipid adsorption and near zero surface tensions upon compression were obtained even with protein-free samples. At physiological pH, only SP-C-containing samples achieved such properties. Lipid adsorption was decreased by prior SP-C depalmitoylation. Bubbles with palmitoylated SP-C were more mechanically stable and required less compression to reach low surface tensions. Subphase depletion experiments showed that dynamically cycled surface layers containing palmitoylated SP-C maintained their surface activity after subphase lipid depletion. In contrast, surface activity was rapidly lost where depalmitoylated SP-C or SP-B was included. Our results indicate that although SP-C palmitoylation has little effect on its ability to enhance lipid adsorption and surface tension reduction, it greatly enhances lipid respreading and film stability and is therefore important for surfactant function.
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Long, Xiaoyun, Lifen He, Yan Zhang y Mingqiao Ge. "Multicomponent Composite Emulsion Treated Geotextile on Landfill with Improved Long-Term Stability and Security". Journal of Engineered Fibers and Fabrics 13, n.º 3 (septiembre de 2018): 155892501801300. http://dx.doi.org/10.1177/155892501801300307.
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Polypropylene geotextiles were treated with multicomponent composite emulsion consist of polytetrafluoroethylene (PTFE), nona-silica and fluorous acrylate. After process of treatment, the treated geotextiles showed greater long-term stability and security than untreated geotextiles on the landfill slope. Firstly, the surface of fibers was investigated by scanning electron microscopy (SEM). Composite thin film was found on them, indicating the successful attachment of ternary composite agents on fibers through pad-drying method. Subsequently, the effect of weathering stability and metallic ions (cupric ions usually) resistance on mechanical properties of samples were studied by using tensile machine. The friction angle values of various interfaces and tension in geotextile versus slope angle were also studied via tilt table test. Our mechanics performance tests indicated that the weathering ability and cupric ions resistance of geotextile were greatly improved via treatment with the composite emulsion. The roughness of geotextile surface, the friction angles of all interfaces and tension in geotextile on landfill slope were decreased.
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Rudachenko, O. O. y T. S. Klebanova. "A Classification of Regions of Ukraine by the Level of Formation of Social Tensions". Business Inform 10, n.º 513 (2020): 128–36. http://dx.doi.org/10.32983/2222-4459-2020-10-128-136.
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A classification of regions of Ukraine by the level of formation of social tensions together with determination of preventive measures aimed at preventing the creation of crisis situations are carried out. It is proved that the socio-economic situation typical for Ukraine has deteriorated significantly. This is evidenced by the decline of a large number of international indicators that characterize the stability of the country’s development. The suggested in the article methodological approach to the classification of regions by the level of formation of social tensions includes two main stages: substantiation of the system of socio-economic indicators that characterize the level of social tension; selection and substantiation of models of classification of regions. The carried out analysis of the values of socio-economic indicators of each cluster allowed to allocate the following classes of regions by the level of formation of social tension: 1st class – increased level of formation of social tensions; 2nd class – low level of formation of social tensions; 3rd class – high level of formation of social tensions. Of particular importance for the research is the 3rd class, i.e., the class with a high level of formation of social tensions, which leads to a crisis. The regions of this class should have serious government support in the social sphere. The results of the research showed that the number of regions classified with high level of social tensions is constantly growing and, unfortunately, the number of regions where the social sphere is more developed is decreasing. It should be noted that this situation is extremely dangerous, because it can lead not only to social, but also economic and political crises. The carried out analysis of the status of region of each of the received classes provides the possibility to prevent aggravation of crises in the social sphere and determine the list of preventive measures that can lead to a decrease in losses both in terms of individual classes and in the State as a whole.
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Michalowski, Radoslaw L. "Failure potential of infinite slopes in bonded soils with tensile strength cut-off". Canadian Geotechnical Journal 55, n.º 4 (abril de 2018): 477–85. http://dx.doi.org/10.1139/cgj-2017-0041.
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Infinite slope analyses are used in practice to assess the safety of slopes against shallow slides, with much of the soil mass moving parallel to a plane failure surface. Stability calculations typically involve the Mohr–Coulomb yield function, but the limitation on tensile strength is discussed and applied in stability considerations for bonded soils. Once the strength envelope is truncated in the tensile regime, the envelope becomes nonlinear and the normality flow rule admits deformation with large volumetric strains. For gentle slopes and in the absence of seepage, the difference in factors of safety calculated with and without tensile strength cut-off is small. However, in the presence of seepage and with increasing inclination of slopes, the difference becomes significant. As the deformation regime moves into the nonlinear portion of the yield envelope, application of the traditional definition of the factor of safety is not straightforward. If the strength envelope is truncated with a circular arc, then the envelope reduced by the factor of safety assumes an elliptical shape. The novelty in this paper is in presenting an analysis for bonded geomaterials with tensile strength cut-off, and indicating that tension cut-off can have a significant impact on the outcome of stability analysis for steep slopes subjected to seepage.
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Georgiou, E., D. T. Papageorgiou, C. Maldarelli y D. S. Rumschitzki. "The double layer–capillary stability of an annular electrolyte fluid surrounding a dielectric-fluid core in a tube". Journal of Fluid Mechanics 226 (mayo de 1991): 149–74. http://dx.doi.org/10.1017/s002211209100232x.
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In this paper we examine the linear stability of an annular film surrounding a dielectric-fluid core in a tube in the presence of double layers of charges at the film core and at the film–tube interfaces, when the fluid-fluid interface is of low tension. In the absence of electrostatic forces, the surface tension force arising from the circumferential curvature destabilizes, and that from the axial curvature stabilizes the system. The competition is such that waves larger than the unperturbed interface circumference are unstable and those shorter are stable. For charged layers in the film, two cases are examined: (i) double-layer repulsion where the volume charge density is everywhere of the same sign and (ii) double-layer attraction where the diffusive layers next to the film interfaces are of opposite signs. In the first case, double-layer repulsion and surface tension lowering stabilize the destabilizing action of the circumferential component of the surface tension force, and a window of stability can exist. In the case of double layers of opposite signs, double-layer attraction destabilizes the system, and growth rates larger than those caused by pure capillarity can arise. Finally, for the case of a core bounded by an infinite electrolyte, surface tension lowering stabilizes the destabilizing action of the circumferential component of the surface tension force and destabilizes the longitudinal one, although the magnitudes of these effects may differ. As a result the thread can become unstable to waves shorter than the interface circumference.
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Varma, Mahesh, Siddhartha Ghosh y Gabriele Milani. "Finite Element Thrust Line Analysis (FETLA) of Axisymmetric Masonry Dome with Meridian Cracks". Applied Mechanics and Materials 865 (junio de 2017): 397–402. http://dx.doi.org/10.4028/www.scientific.net/amm.865.397.
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Many masonry domes in their lower portion are subjected to hoop tensile forces which mostly lead to vertical cracks appearing along the dome's meridian planes. A close inspection of any such dome reveals these hoop tension cracks. The dome stands as a series of arches with common key stone, with cracks as a matter of non-structural consequences. Different strategies have been considered historically to arrest these cracks. The provision of tension ring mechanism adds to the stability of these domes, and hence many masonry domes are retrofitted with the provision of the tension rings using steel and FRP rings. The challenge in such retrofitting will remain to analyze its effect on stability of these masonry domes, more specifically in absence of reliable mechanical properties of such masonry domes. This paper presents a simplified analysis procedure combining thrust line analysis with the finite element analysis called here as Finite Element Thrust Line Analysis (FETLA). The development of a new element suitable for masonry dome analysis to include the effect of hoop tension cracks is demonstrated. The orthotropic material properties are utilized for penalty approach to allow redistribution of the forces from meridian direction to the hooping rings, with thrust line approaching the extrados or intrados of the dome. The analysis results of FETLA are validated with the previously available results. The analysis method proposed in this paper gives the rational estimates for the failure load without utilizing inelastic properties of the material to model the hoop tension cracks and its propagation.
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Gur’yanov, G. N. y O. B. Kalugina. "INCREASE OF WIRE STRESS STABILITY DEPENDING ON ANTI-TENSION ACTION WHEN FRICTION COEFFICIENT IS INCONSTANT". Izvestiya. Ferrous Metallurgy 62, n.º 4 (20 de junio de 2019): 315–23. http://dx.doi.org/10.17073/0368-0797-2019-4-315-323.
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The strain parameters instability causes variable axial stress during the drawing process. Contact friction specification varies in the shortest time and depends on many factors: homogeneity physico-mechanical properties of the processed material along the length of the pulled billet, quality of technological lubrication, stability of tension force of the billet at the entrance of deformation center and cooling intensity of the fiber, suction drums, washers, rollers, etc. To estimate the effect of friction coefficient on stability of drawing force (stress), first derivative with respect to friction coefficient in drawing equation is used. The first derivative dependence on drawing coefficient is constructed for different hardening models and deformation parameters. Action of anti-tension was investigated when drawing on stressed state of a circular continuous profile. Studies have been carried out for simulation models of hardening. In the course of study, it was proved that it is possible to estimate instability of stressed state by the first derivative with respect to magnitude, depending on friction coefficient of the equation that determines drawing stress. For different deformation parameters, the first derivative with respect to friction coefficient is calculated for the equation determining axial drawing stress. A decrease in magnitude of the derivative is shown with an increase in anti-tension, which indicates expediency of drawing with antitension to stabilize drawing force and to reduce fatigue wear of dies working surface. Calculations were performed for different values of friction coefficient for drawing under the conditions of presence and absence of drawing cylinder and slope angle of drawing cone to drawing axis, mechanical properties of the billet for drawing, and for various coefficients of its hardening. The stabilizing effect of drawing cylinder of dies on drawing stresses with an increased friction coefficient is shown. Instability of drawing stress from deviation of nominal value of friction coefficient depends on values of other strain parameters. In conditions of drawing cylinder presence and small amount of deformation in drawing path and smaller initial friction coefficient, change in its magnitude has a greater effect on stability of the stressed state. Increase in drawing stress stability positively affects quality of wire, operational stability of units and drawing-line elements, for example, due to decrease in fatigue wear of die working surfaces, drawing drums, bypass and straightening rollers. Drawing with anti-tension and the use of special drawing tools stabilize stress state in deformation zone.
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SHEN, HAIJUN. "TENSILE PROPERTIES AND ELECTRONIC STRUCTURES OF C240 NANOTUBE AND 4C60 FULLERENE POLYMERS". International Journal of Nanoscience 05, n.º 01 (febrero de 2006): 99–107. http://dx.doi.org/10.1142/s0219581x06004073.
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The classical MD (Molecular Dynamics) method was used to simulate the tension of three kinds of C 240 isomers, i.e., C 240 nanotube, chain-like 4C 60 fullerene polymer and peanut-like 4C 60 fullerene polymer. Then, the semi-empirical PM3 method was used to calculate their electronic structures under tension. Lastly, according to the calculated results, their differences in tensile mechanical properties, as well as the change of their FMO (Frontier Molecular Orbital) energy during tension, were discussed. It is shown that: (1) the load-support capability of the C 240 molecules has the order of C 240 nanotube > peanut-like 4C 60 polymer > linear 4C 60 polymer, but their deformation-support capability has the contrary order, (2) of the C 240 isomers, the C 240 nanotube has the best chemical stability, and the chain-like 4C 240 molecule has the worst one, and (3) the deformed C 240 isomers have narrower energy-gap between their LUMO and HOMO, and higher chemical activity.
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Yamaguchi, Eiichiro, Matthew J. Giannetti, Matthew J. Van Houten, Omid Forouzan, Sergey S. Shevkoplyas y Donald P. Gaver. "The unusual symmetric reopening effect induced by pulmonary surfactant". Journal of Applied Physiology 116, n.º 6 (15 de marzo de 2014): 635–44. http://dx.doi.org/10.1152/japplphysiol.00814.2013.
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This study investigates the stability of a finger of air as it propagates into a liquid-filled model of a liquid-filled model of a pulmonary bifurcation. We seek to elucidate the stability characteristics of the reopening of daughter airways, an event that may be important to the treatment of acute lung disease. To do so, we investigated the symmetry of reopening under conditions of nearly constant surface tension with 1) purified H2O or 2) an anionic surfactant (sodium dodecyl sulfate). Dynamic surface tension was investigated using pulmonary surfactant (Infasurf) with and without the presence of albumin. Flow visualization was accomplished using a microparticle image velocimetry (μ-PIV)/shadowgraph system through which we measured 1) the propagation velocity of the finger of air that reopens each daughter branch, and 2) the instantaneous and averaged velocity field of liquid phase surrounding the tip of the propagating bubble. Only pulmonary surfactant demonstrated the ability of maintaining a nearly symmetric propagation in the daughter channels, which is likely to lead to homogeneous airway reopening. In contrast, when pulmonary surfactant was inactivated by albumin or when the system was held at a nearly constant surface tension, reopening occurred asymmetrically. Our analysis suggests that Infasurf's dynamic surface tension qualities are important to stabilize the removal of liquid obstructions. This demonstrates a new important function of pulmonary surfactant for airway reopening of a multibranched network.