The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Dongsheng Wen - One of the best experts on this subject based on the ideXlab platform.
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Spreading of triple line and dynamics of bubble growth inside nanoparticle dispersions on top of a Substrate Plate.
Journal of colloid and interface science, 2011Co-Authors: Saeid Vafaei, Dongsheng WenAbstract:Abstract This work investigates the feasibility of engineering surface wettability by using different nanoparticles. As an illustration, detailed formation of gas bubbles on top of a stainless steel Substrate Plate in a quiescent pool of aqueous gold and alumina nanofluids is studied. The presence of nanoparticles is shown to be able to modify the dynamics of triple line and bubble growth significantly. An early pinning of the bubble triple line is observed and a larger bubble contact angle is found for bubbles growing in a gold nanofluid, whereas an opposite phenomenon is observed for bubbles growing in an alumina nanofluid compared to those of pure water. Other bubble parameters such as departure volume, bubble frequency, and waiting time of bubble formation are also affected by the presence of nanoparticles. The variation of solid surface tensions due to the existence of nanoparticles and the resultant force at the triple line should be responsible for such differences. Such results illustrate the big potential of nanoparticle in engineering surface wettability of a solid–liquid–gas system.
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Effect of Nanoparticles on the Spreading of Bubble Triple Line on Top of a Stainless Steel Substrate Nozzle
ASME 2010 8th International Conference on Nanochannels Microchannels and Minichannels: Parts A and B, 2010Co-Authors: Saeid Vafaei, Dongsheng WenAbstract:The purpose of this study is to investigate the effect of gold nanofluid on the formation of gas bubbles on top of a stainless steel Substrate Plate nozzle. The experiment reveals a unique phenomenon of enhanced pinning of the triple line of gold nanofluids for bubbles forming on the Substrate Plate, i.e the gold nanoparticles are found to prevent the spreading of the triple line during the bubble formation. Different to the liquid droplet measurement, the bubble contact angle is found to be slightly larger for formation of bubbles inside gold nanofluids. It is also observed that bubbles develop earlier inside the nanofluids with reduced bubble departure volume and increased bubble formation frequency. The shape of the bubble is found to be in good agreement with predictions of the Laplace-Young equation under the low gas flow rates inside water. Such a good agreement is also observed for bubbles forming inside nanofluids except a few characteristic points. The variation of solid surface tensions and the resultant force balances at the triple line are believed to be responsible for the modified dynamics of the triple line inside gold nanofluids and subsequent bubble formation.Copyright © 2010 by ASME
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Bubble Formation on Top of Submerged Needle and Substrate Plates
ASME 2010 8th International Conference on Nanochannels Microchannels and Minichannels: Parts A and B, 2010Co-Authors: Saeid Vafaei, Panagiota Angeli, Dongsheng WenAbstract:The purpose of this investigation is to conduct a comparative study on the formation of bubble on top of a stainless steel needle nozzle and two Substrate Plate nozzles. The experimental study is conducted on a submerged needle nozzle with internal diameter of 0.51 mm and 0.155 mm thickness, and two stainless steel Substrate Plates with nozzle diameter of 0.4 mm and 0.51mm respectively. The experiment is carried out under low gas flow rates (0.015 ∼ 0.85 ml/min). The bubble formation is recorded by a high speed video camera and detailed characteristics of bubble formation such as the variations of instantaneous contact angles, bubble heights and the radii of contact lines are obtained, which show a weak dependence on the flow rate under the conditions of current work. Using experimentally captured values of the height of bubble and the radius of contact line, the Young-Laplace equation is solved, which is found to be able to predict bubble evolution quite well until the last milliseconds before the detachment. Interestingly, it is found that the trends of the variation of bubble volume expansion rate from the stainless steel needle and the Substrate Plate are different, however, the rest of bubble characteristics such as radius of contact line, bubble height, contact angle, and radius of curvature of bubble apex follow same trends as the time and bubble volume change for formation of bubble on top of needle and Substrate nozzles. A force analysis of bubble formation reveals that the observed variations of contact angles and other characteristics during the bubble growth period are associated with the relative contribution of surface tension, buoyancy and gravitational forces.Copyright © 2010 by ASME
Saeid Vafaei - One of the best experts on this subject based on the ideXlab platform.
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Spreading of triple line and dynamics of bubble growth inside nanoparticle dispersions on top of a Substrate Plate.
Journal of colloid and interface science, 2011Co-Authors: Saeid Vafaei, Dongsheng WenAbstract:Abstract This work investigates the feasibility of engineering surface wettability by using different nanoparticles. As an illustration, detailed formation of gas bubbles on top of a stainless steel Substrate Plate in a quiescent pool of aqueous gold and alumina nanofluids is studied. The presence of nanoparticles is shown to be able to modify the dynamics of triple line and bubble growth significantly. An early pinning of the bubble triple line is observed and a larger bubble contact angle is found for bubbles growing in a gold nanofluid, whereas an opposite phenomenon is observed for bubbles growing in an alumina nanofluid compared to those of pure water. Other bubble parameters such as departure volume, bubble frequency, and waiting time of bubble formation are also affected by the presence of nanoparticles. The variation of solid surface tensions due to the existence of nanoparticles and the resultant force at the triple line should be responsible for such differences. Such results illustrate the big potential of nanoparticle in engineering surface wettability of a solid–liquid–gas system.
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Effect of Nanoparticles on the Spreading of Bubble Triple Line on Top of a Stainless Steel Substrate Nozzle
ASME 2010 8th International Conference on Nanochannels Microchannels and Minichannels: Parts A and B, 2010Co-Authors: Saeid Vafaei, Dongsheng WenAbstract:The purpose of this study is to investigate the effect of gold nanofluid on the formation of gas bubbles on top of a stainless steel Substrate Plate nozzle. The experiment reveals a unique phenomenon of enhanced pinning of the triple line of gold nanofluids for bubbles forming on the Substrate Plate, i.e the gold nanoparticles are found to prevent the spreading of the triple line during the bubble formation. Different to the liquid droplet measurement, the bubble contact angle is found to be slightly larger for formation of bubbles inside gold nanofluids. It is also observed that bubbles develop earlier inside the nanofluids with reduced bubble departure volume and increased bubble formation frequency. The shape of the bubble is found to be in good agreement with predictions of the Laplace-Young equation under the low gas flow rates inside water. Such a good agreement is also observed for bubbles forming inside nanofluids except a few characteristic points. The variation of solid surface tensions and the resultant force balances at the triple line are believed to be responsible for the modified dynamics of the triple line inside gold nanofluids and subsequent bubble formation.Copyright © 2010 by ASME
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Bubble Formation on Top of Submerged Needle and Substrate Plates
ASME 2010 8th International Conference on Nanochannels Microchannels and Minichannels: Parts A and B, 2010Co-Authors: Saeid Vafaei, Panagiota Angeli, Dongsheng WenAbstract:The purpose of this investigation is to conduct a comparative study on the formation of bubble on top of a stainless steel needle nozzle and two Substrate Plate nozzles. The experimental study is conducted on a submerged needle nozzle with internal diameter of 0.51 mm and 0.155 mm thickness, and two stainless steel Substrate Plates with nozzle diameter of 0.4 mm and 0.51mm respectively. The experiment is carried out under low gas flow rates (0.015 ∼ 0.85 ml/min). The bubble formation is recorded by a high speed video camera and detailed characteristics of bubble formation such as the variations of instantaneous contact angles, bubble heights and the radii of contact lines are obtained, which show a weak dependence on the flow rate under the conditions of current work. Using experimentally captured values of the height of bubble and the radius of contact line, the Young-Laplace equation is solved, which is found to be able to predict bubble evolution quite well until the last milliseconds before the detachment. Interestingly, it is found that the trends of the variation of bubble volume expansion rate from the stainless steel needle and the Substrate Plate are different, however, the rest of bubble characteristics such as radius of contact line, bubble height, contact angle, and radius of curvature of bubble apex follow same trends as the time and bubble volume change for formation of bubble on top of needle and Substrate nozzles. A force analysis of bubble formation reveals that the observed variations of contact angles and other characteristics during the bubble growth period are associated with the relative contribution of surface tension, buoyancy and gravitational forces.Copyright © 2010 by ASME
Shigeki Saito - One of the best experts on this subject based on the ideXlab platform.
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Non-impact electrostatic micromanipulation by voltage sequence for time
MRS Online Proceedings Library, 2011Co-Authors: Shigeki Saito, Kunio Takahashi, Masataka UragoAbstract:This paper proposes how to determine a voltage sequence for time to realize a non-impact electrostatic micromanipulation by kinetic control of a detached particle. The system consists of a manipulation probe, a spherical microparticle, and a Substrate Plate. These objects are all conductive. The particle initially sticks to the probe tip due to adhesional force and is detached by the applied voltage. The force on the particle, which is generated by electrostatic interaction, is evaluated through a boundary element method. Although the numerical method is used, all the parameters are normalized. Based on the evaluation, we propose the simple method by accelerating and decelerating voltage, and clearly express the conditions of voltage and time by considering the total work to the particle during its flight. The discussion about the time reveals the feasibility of the method from the viewpoint of the through-rate of a power-source.
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Non-impact deposition for electrostatic micromanipulation of a conductive particle by a single probe
Journal of Micromechanics and Microengineering, 2008Co-Authors: Shigeki Saito, Masaki SonodaAbstract:This note reports on an experimental demonstration of non-impact deposition for electrostatic micromanipulation of a conductive particle by a single probe. The experimental system consists of a probe, a 30-micrometers-in-diameter particle, and a Substrate Plate. The particle, initially adhering to the probe tip, is detached and deposited onto the Substrate by rapid change of the probe?Substrate voltage designed on the basis of calculation by a boundary element method. The feasibility is experimentally shown; furthermore, the method of modifying the voltage sequence to improve the rate of success by considering the finite slew rate of the power source is discussed.A correction was made to this article (in the introduction) on 18 September 2008. The corrected electronic version is identical to the print version.
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Kinetic control of a particle by voltage sequence for a nonimpact electrostatic micromanipulation
Applied Physics Letters, 2003Co-Authors: Shigeki Saito, Hideo Himeno, Kunio Takahashi, Masataka UragoAbstract:This letter describes a calculation of a voltage sequence to obtain kinetic control of a particle for nonimpact electrostatic micromanipulation. The system consists of conductive objects: A manipulation probe, a spherical particle, and a Substrate Plate. The particle, initially adhering to the probe tip, is detached by an applied voltage. The electrostatic force acting on the particle during its movement to the Substrate is calculated by a numerical boundary element method. We determine the voltage and time sequence for nonimpact deposition of the particle onto the Substrate by considering the total work to the particle. The calculation provides the power source requirements for nonimpact particle deposition.
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IROS - Electrostatic detachment of a micro-object from a probe by applied voltage
IEEE RSJ International Conference on Intelligent Robots and System, 1Co-Authors: Shigeki Saito, Kunio Takahashi, H. Himeno, T. OnzawaAbstract:In micro-manipulation, the influence of gravitational force becomes extremely small. The adhesional force is more significant for smaller objects. An adhered object can be detached by electrostatic interaction. The electrostatic force generated by the applied voltage and the voltage required for detachment are theoretically analyzed by using the boundary element method (BEM). The system consists of a manipulation probe, a spherical micro-object, and a Substrate Plate. These object are all conductive. In this study, the voltage for detachment of micro-sphere with 30 /spl mu/m diameter was experimentally clarified, and was compared with the voltage predicted by the BEM analysis. This result gives us the knowledge about the strategy for reliable electrostatic micro-manipulation.
Masataka Urago - One of the best experts on this subject based on the ideXlab platform.
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Non-impact electrostatic micromanipulation by voltage sequence for time
MRS Online Proceedings Library, 2011Co-Authors: Shigeki Saito, Kunio Takahashi, Masataka UragoAbstract:This paper proposes how to determine a voltage sequence for time to realize a non-impact electrostatic micromanipulation by kinetic control of a detached particle. The system consists of a manipulation probe, a spherical microparticle, and a Substrate Plate. These objects are all conductive. The particle initially sticks to the probe tip due to adhesional force and is detached by the applied voltage. The force on the particle, which is generated by electrostatic interaction, is evaluated through a boundary element method. Although the numerical method is used, all the parameters are normalized. Based on the evaluation, we propose the simple method by accelerating and decelerating voltage, and clearly express the conditions of voltage and time by considering the total work to the particle during its flight. The discussion about the time reveals the feasibility of the method from the viewpoint of the through-rate of a power-source.
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Kinetic control of a particle by voltage sequence for a nonimpact electrostatic micromanipulation
Applied Physics Letters, 2003Co-Authors: Shigeki Saito, Hideo Himeno, Kunio Takahashi, Masataka UragoAbstract:This letter describes a calculation of a voltage sequence to obtain kinetic control of a particle for nonimpact electrostatic micromanipulation. The system consists of conductive objects: A manipulation probe, a spherical particle, and a Substrate Plate. The particle, initially adhering to the probe tip, is detached by an applied voltage. The electrostatic force acting on the particle during its movement to the Substrate is calculated by a numerical boundary element method. We determine the voltage and time sequence for nonimpact deposition of the particle onto the Substrate by considering the total work to the particle. The calculation provides the power source requirements for nonimpact particle deposition.
Udo Fritsching - One of the best experts on this subject based on the ideXlab platform.
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Investigating the Boiling and Transition Zones and the Rewetting Process of a Substrate Plate during Submerged Liquid Jet Cooling
Numerical Heat Transfer Part A: Applications, 2014Co-Authors: P. Stark, Udo FritschingAbstract:A numerical model is developed to simulate the flow field, as well as the conjugate heat transfer process, during transient cooling of a flat Substrate Plate cooled by a single submerged impinging water jet. At wall temperatures above the liquid boiling point, the vapor formation process in different boiling regimes and the interaction of the vapor phase with the developing jet-flow field are addressed in the model. The developing submerged jet flow, the conjugate heat transfer from a flat Substrate Plate and the resulting temperature distribution inside the Plate are simulated with respect to the transient boiling phase distribution. The influence of the liquid subcooling temperature (40 K ≤ T sub ≤ 80 K), the Plate thickness (0.5 ≤ h/d ≤ 15), the conductivity of the solid Substrate material (18 W/(m K) ≤ λ solid ≤ 380 W/(m K)) on the transition region positions (e.g., the Leidenfrost point), and the transition temperatures are analyzed.
