المؤلفون: Long Hoang

المصدر: Advances in Sciences and Technology, Vol 18, Iss 4, Pp 347-354 (2024)

مصطلحات موضوعية: gear profile, compressor screw, contact line, meshing condition, envelope theory, Engineering (General). Civil engineering (General), TA1-2040

الوصف: The theory of enveloping, which determines the envelope to a family of surfaces, the meshing equations of kinematics pairs, including pinion and gear, cutting toll and gear, is widely used in Mechanical Engineering. This paper presents a new envelope computational method for profiling the meshing gear pair. It uses the normal projection of the instantaneous relative rotation axis of the kinematic pair onto the pinion surface to generate the contact line and then automatically computes geometric data of this contact line to create the gear tooth surface. As the profile complexity, the reverse engineering of compressor screw pair was a typical proper example to verify and clarify the proposed method. The method can generate the meshing surface pair with high accuracy: the 3D comparison average error of the surfaces generated by the proposed method and the Boolean method is 0.004 mm, and their RMS error is 0.01 mm. The novel idea of the proposed method is that the contact line, which is used to calculate gear surface, is created easier than solving complex meshing equations, which most previous work used. The proposed method in detail with an algorithm can be used as well for reverse engineering of air compressor screw pair as for parallel axixes heliacal gear pair

وصف الملف: electronic resource

العلاقة: http://www.astrj.com/A-New-Envelope-Computational-Method-for-Meshing-Heliacal-Gears-Profiling-Applied,189674,0,2.htmlTest; https://doaj.org/toc/2080-4075Test; https://doaj.org/toc/2299-8624Test

الوصول الحر: https://doaj.org/article/343039ae31cc4c9a9875ee93cb3952f9Test

المؤلفون: Tkach Pavlo, Reviakina Olga, Kryvosheia Anatolii, Melnyk Volodymyr, Ustynenko Oleksandr, Protasov Roman

المصدر: Journal of Mechanical Engineering, Vol 73, Iss 2, Pp 181-192 (2023)

مصطلحات موضوعية: arc-tooth-trace gears, profile shift coefficient, sliding velocity, rolling velocity of mating teeth surfaces, reduced curvature, specific sliding, angle between sliding velocity vector and contact line, Engineering (General). Civil engineering (General), TA1-2040

الوصف: Based on the results obtained in the previous research, the values of meshing characteristics of profile shifted quasi-involute arc-tooth-trace gears is calculated. The influence of the values of profile shift coefficient and the angle of tooth trace on meshing characteristic distribution on the tooth flank surface along tooth trace is defined. The results can be used for design of profile shifted quasi-involute arc-tooth-trace gears, cut by Gleason-type cutters with different profile angle value.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2450-5471Test

الوصول الحر: https://doaj.org/article/9b6010fd7b6241e6aeb25adcef279156Test

المؤلفون: Yoshitaka YAMASHITA, Koki SATO

المصدر: Nihon Kikai Gakkai ronbunshu, Vol 90, Iss 932, Pp 23-00313-23-00313 (2024)

مصطلحات موضوعية: hinged cantilever, tensioning device, overhead contact line, equilibrium point, Mechanical engineering and machinery, TJ1-1570, Engineering machinery, tools, and implements, TA213-215

الوصف: Overhead contact lines (OCLs) are subjected to longitudinal displacement due to factors such as temperature changes and external force. Excessive longitudinal displacement may prevent the tension balancers from performing their proper tension adjustment function. It is therefore important to develop a method for calculating the longitudinal displacement of OCLs and to make it possible to predict the longitudinal displacement in response to changes in temperature and external forces. This paper presents a model to represent the longitudinal displacement of OCLs on a curved track installing tensioning devices and hinged cantilevers at each support point and proposes calculation methods to find the equilibrium points of the longitudinal displacement of the OCL. Furthermore, the validation of the proposed calculation methods was confirmed by scale model tests.

وصف الملف: electronic resource

العلاقة: https://www.jstage.jst.go.jp/article/transjsme/90/932/90_23-00313/_pdf/-char/enTest; https://doaj.org/toc/2187-9761Test

الوصول الحر: https://doaj.org/article/1ad37d93b89041b7b25662fe54820a09Test

المؤلفون: Wenjun Tan, Chuang Zhang, Ruiqian Wang, Yiwei Zhang, Lianchao Yang, Qin Chen, Feifei Wang, Yezhong Tang, Ning Xi, Lianqing Liu

المصدر: Advanced Intelligent Systems, Vol 6, Iss 2, Pp n/a-n/a (2024)

مصطلحات موضوعية: hexagonal-textured surfaces, moving contact line, superhydrophilic, superspreading, Computer engineering. Computer hardware, TK7885-7895, Control engineering systems. Automatic machinery (General), TJ212-225

الوصف: The dynamic spreading mechanism of liquid on a specific surface is vital for understanding interface wetting and antifouling. Whereas, how to control the spreading process and accelerate the spreading speed is a major challenge. The rock‐climbing fish is characterized by its alepidote feature that lives in stream habitats dominated by strong currents. The mucus on its body surface plays a vital role in its adherence and maintenance of antifouling and antibacterial properties. However, the rapid, uniform, and efficient spreading mechanism of mucus on the fish body surface remains largely unknown. Herein, it is revealed that the surface of the rock‐climbing fish is overlaid fully by the microhexagonal texture structure. This hexagonal structure shows a superspreading effect on liquid diffusion, resulting from testing with bionic microfabrication inspired by the rock‐climbing fish. It is demonstrated that the microhexagonal‐textured surface can enhance liquid spreading quickly and evenly on the surface by regulating the moving contact line of the liquid. This kind of superspreading mechanism has great potential applications in the antifouling, electroencephalogram electrode interfaces, flexible skin sensors, and interfacial lubrication of underwater surfaces.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2640-4567Test

الوصول الحر: https://doaj.org/article/34bc8ce023e4479e8a406dabcfaa436eTest

المؤلفون: Shen, Lingyue

المساهمون: Lin, Ping, Kyza, Irene

مصطلحات موضوعية: phase-field, vesicle motion, vesicle interaction, moving contact line, General Navier Boundary Condition, energy preserving, finite element method, discrete energy law

الوصف: Phase-field theory is a powerful method which is widely used in dealing with multiphase problem in fluid dynamics in recent years. In this thesis, models of moving contact lines and vesicle motion, deformation and interaction would be established with phase-field method. Energy variational approach is used to derive the governing equations from some basic energy assumption. C⁰ finite element scheme is given to perform numerical test. Continuous and discrete energy decaying law are also given to prove the feasibility of the model. Finally, numerical simulation is applied. A number of results in different conditions are shown. By comparing with experimental data from previous research, the models are proven to be with good accuracy.

الوصول الحر: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.862293Test

المؤلفون: Noritsugu MAEDA

المصدر: Journal of Advanced Mechanical Design, Systems, and Manufacturing, Vol 18, Iss 1, Pp JAMDSM0006-JAMDSM0006 (2024)

مصطلحات موضوعية: face gear, involute helical gear, crossed gears, straight line of action, tooth surface design, meshing contact method, meshing contact line of action, meshing contact surface of action, Engineering machinery, tools, and implements, TA213-215, Mechanical engineering and machinery, TJ1-1570

الوصف: The purpose of this study was to simplify the design of the tooth surface of face gear and to clarify the optimization method of the specification setting. Face gears have long been used in fishing spinning reels as a speed-increasing gear. Recently, face gears have also been adapted to geared motors for orthogonal reduction gears. However, the design method of the face gear is not supported by a standard theory, and its application is not common. This paper reports the study of face gear that meshes with involute helical gear with offset. The curved surfaces of the face gear tooth can be generated using the involute helical gear surface, which is mesh constant rotation speed. To clarify the meshing of the face gear, the author introduced the idea that the meshing contact progresses along a straight line of action. The meshing point between the involute helical and face gear proceeds at a constant speed along the straight line of action. The straight line of action is continuous and exists as a curved surface. In this method, the meshing contact is always made in the direction normal to the tooth surface of the involute pinion. This method is based on a simple theory and can be used to obtain the tooth surface coordinates of a face gear without complicated repetitive calculations. The tooth profile of the face gear calculated by the conventional generation method using a numerical analysis and calculated by the proposed meshing contact method were compared and, except for the interference area, they were the same. Using this method, design of the tooth surface of a face gear can be simplified.

وصف الملف: electronic resource

العلاقة: https://www.jstage.jst.go.jp/article/jamdsm/18/1/18_2024jamdsm0006/_pdf/-char/enTest; https://doaj.org/toc/1881-3054Test

الوصول الحر: https://doaj.org/article/aa57aea71d2f41b5bec9eb642984f93dTest

المؤلفون: Nikolayev, Vadim, S, Wei, Linkai, Bois, Guillaume

المساهمون: Service de physique de l'état condensé (SPEC - UMR3680), Institut Rayonnement Matière de Saclay (DRF) (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CEA- Saclay (CEA), Service de Thermo-hydraulique et de Mécanique des Fluides (STMF), Département de Modélisation des Systèmes et Structures (DM2S), Institut des Sciences Appliquées et de la Simulation pour les énergies bas carbone (ISAS), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut des Sciences Appliquées et de la Simulation pour les énergies bas carbone (ISAS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, GDR 2799 Micropesanteur Fondamentale & Appliquée

المصدر: ISSN: 1742-6596 ; EISSN: 1742-6588.

مصطلحات موضوعية: contact line, evaporation, microregion, boiling, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]

الوصف: International audience ; Abstract This contact line vicinity model is conceived as a subgrid model for the DNS of bubble growth in boiling. The model is based on the hydrodynamic multiscale theory and is suitable for the partial wetting case. On the smallest length scale (distance from the contact line) ∼ 100 nm, the interface slope is controlled by the Voinov angle. It is the static apparent contact angle (ACA) that forms due to evaporation, similarly to previous models neglecting the contact line motion. The calculation of the Voinov angle is performed with the generalized lubrication approximation and includes several nanoscale effects like those of Kelvin and Marangoni, vapor recoil, hydrodynamic slip length and interfacial kinetic resistance. It provides the finite values of the heat flux, pressure and temperature at the contact line. The dynamic ACA is obtained with the Cox-Voinov formula. The microscopic length of the Cox-Voinov formula (Voinov length) is controlled mainly by the hydrodynamic slip. The integral heat flux passing through the contact line vicinity is almost independent of the nanoscale phenomena, with the exception of the interfacial kinetic resistance and is mostly defined by the dynamic ACA. Both the dynamic ACA and the integral heat flux are the main output parameters of the subgrid model, while the local superheating and the microscopic contact angle are the main input parameters. The model is suitable for the grid sizes > 1 µ m.

العلاقة: cea-04602109; https://cea.hal.science/cea-04602109Test; https://cea.hal.science/cea-04602109/documentTest; https://cea.hal.science/cea-04602109/file/MicroCLEuroTherm2024.pdfTest

الإتاحة: https://doi.org/10.1088/1742-6596/2766/1/012123Test
https://cea.hal.science/cea-04602109Test
https://cea.hal.science/cea-04602109/documentTest
https://cea.hal.science/cea-04602109/file/MicroCLEuroTherm2024.pdfTest

المؤلفون: Mondal, Md Tanbin Hasan

المصدر: Doctoral Dissertations

مصطلحات موضوعية: Phase-change heat transfer, MEMS device, Moving contact line, Capacitance sensing, Thermal sensing, Droplet evaporation, Engineering, Nanoscience and Nanotechnology

الوصف: Despite the significant importance and widespread use of phase-change cooling techniques, there are still fundamental questions about the microscopic processes that govern the heat transfer mechanisms. In order to gain a better understanding of the underlying physics involved, it is essential to have information at the microscale regarding the surface temperature distribution with time as well as the location and speed of the moving contact line (MCL). A comprehensive understanding of heat transfer mechanisms and phase-interface behavior during phase-change cooling is crucial for improving heat transfer models, optimizing surface engineering, and maximizing overall effectiveness. Firstly, this dissertation presents a capacitance-based microdevice capable of tracking a moving phase interface at the microscale for unconstrained liquid droplets. This microdevice is comprised of an array of planar interdigitated electrodes beneath a thin insulating polymer layer. During the experiments, monitoring changes in capacitance with time facilitated sensing the MCL location and speed as it passes over each capacitance sensor. This capacitive sensing scheme is noninvasive to the system under study, allowing its implementation into many types of existing hardware and devices and not requiring optical access to the phase change area of the device. Implementing multiple capacitance sensors in adjacent proximity for a semiconducting based demonstrated a few limitations, including coupling effects, but it did not prevent the effective detection of MCL. Utilizing a dielectric substrate demonstrated notable improvements, including but not limited to increased capacitance signal outputs and reduced coupling effects for multiple sensors in adjacent proximity. Moreover, this sensing scheme demonstrated the efficient tracking of MCL during droplet evaporation across different surface temperatures, establishing its functionality at elevated temperatures and during phase-change heat transfer processes. Next, multifunctional sensing in an ...

وصف الملف: application/pdf

العلاقة: https://digitalcommons.latech.edu/dissertations/1016Test; https://digitalcommons.latech.edu/context/dissertations/article/2029/viewcontent/Dissertation___Md_Tanbin_Hasan_Mondal.pdfTest

الإتاحة: https://digitalcommons.latech.edu/dissertations/1016Test
https://digitalcommons.latech.edu/context/dissertations/article/2029/viewcontent/Dissertation___Md_Tanbin_Hasan_Mondal.pdfTest

المؤلفون: Franiatte, Sylvain, Paredes, Germercy, Ondarçuhu, Thierry, Tordjeman, Philippe

المساهمون: Institut de mécanique des fluides de Toulouse (IMFT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Pontificia Universidad Católica Madre y Maestra (PUCMM), CNRS International Research Project NEWCA, Fondo Nacional de Innovacìon y Desarrollo Cientìfico y Tecnològico (FONDOCyT), Dominican Republic, Subvenciòn no. 2022-1A1-096, ANR-23-CE30-0041,COCLICO,Physique de la ligne de contact : de la physico-chimie à l'hydrodynamique(2023)

المصدر: ISSN: 1744-683X.

مصطلحات موضوعية: wetting dynamics, contact line, hysteresis, dissipation, atomic force microscopy, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]

الوصف: International audience ; Understanding the origin of the dissipative mechanisms that control the dynamics of a contact line is a real challenge. In order to study the energy dissipation at the contact line when a moving meniscus encounters topographical defects, we developed atomic force microscopy (AFM) experiments using nanofibers with nanometer scale defects. These experiments realized with three liquids are performed in two AFM modes: the contact mode (C-AFM) is used to measure the energy associated with the contact angle hysteresis in the limit of a static situation, deduced from advancing and receding dipping experiments on an isolated defect; the frequency-modulation mode (FM-AFM) is performed at different amplitudes and then velocities to measure the energy dissipated as the contact line moves over the same defect. Strong dissipation peaks appear above a threshold amplitude characteristic of the liquid and the defect, which is determined by the width of the hysteresis measured in statics. Furthermore, the dissipation energy of the moving contact line measured in dynamics is equal to the hysteresis capillary energy whatever the amplitude and is therefore independent of the contact line velocity. These results point out that the defect contribution to dissipation energy of a moving contact line on real surfaces is only governed by the pinning–depinning energy with no contribution of viscous effects. ; Comprendre l'origine des mécanismes dissipatifs qui contrôlent la dynamique d'une ligne de contact est un véritable défi. Afin d'étudier la dissipation d'énergie à la ligne de contact lorsqu'un ménisque en mouvement rencontre des défauts topographiques, nous avons développé des expériences de microscopie à force atomique (AFM) en utilisant des nanofibres avec des défauts à l'échelle du nanomètre. Ces expériences réalisées avec trois liquides sont effectuées dans deux modes AFM : le mode contact (C-AFM) est utilisé pour mesurer l'énergie associée à l'hystérésis de l'angle de contact dans la limite ...

العلاقة: hal-04555516; https://hal.science/hal-04555516Test; https://hal.science/hal-04555516/documentTest; https://hal.science/hal-04555516/file/2024_SoftMatt_Dissipation_defect.pdfTest

الإتاحة: https://doi.org/10.1039/d4sm00161cTest
https://hal.science/hal-04555516Test
https://hal.science/hal-04555516/documentTest
https://hal.science/hal-04555516/file/2024_SoftMatt_Dissipation_defect.pdfTest

المؤلفون: Arnov Paul, Apurba Roy, Purbarun Dhar

مصطلحات موضوعية: Biophysics, Biochemistry, Genetics, Biotechnology, Inorganic Chemistry, Physical Sciences not elsewhere classified, thereby locally augmenting, internal marangoni thermo, internal marangoni hydrodynamics, higher temperature gradient, governing equations corresponding, fully coupled manner, capillary bridge profiles, appropriate boundary conditions, phase contact point, higher confinement curtails, evaporating capillary bridges, bulge region develops, confined ambient surrounding, contact line dynamics, confined capillary bridges, cca modes ), bridge confinement phenomenon, wettability effects play, evaporation rate due, confinement phenomenon, cca modes, contact lines, shaped region, fluid dynamics

الوصف: We probe the evaporation mechanisms of wettability-moderated, confined capillary bridges and bulges. For the first time, we explore the internal Marangoni hydrodynamics and external Stefan advection dynamics in the surrounding gaseous domain due to evaporative effects. A transient simulation approach based on the level set (LS) method and the Arbitrary Lagrangian–Eulerian (ALE) framework was adopted to computationally model the capillary bridge profiles and evaporation phenomenon with generic contact line dynamics (both CCR and CCA modes). The governing equations corresponding to the transport processes in both the liquid and gaseous domains are simulated in a fully coupled manner with appropriate boundary conditions to precisely trace the liquid–vapor interface and the three-phase contact point during evaporation. The effect of the bridge confinement phenomenon, i.e., the extent of confined ambient surrounding the liquid–vapor interface between the solid surfaces, is explored. Also, the role of wetting state and contact line dynamics during CCR and CCA modes of evaporation were probed, and good agreement with experimental observations was noted. Results show that the evaporation rate is primarily dictated by the confinement phenomenon, and wettability effects play a marginal role. A higher confinement curtails the evaporation rate due to an increased local vapor concentration around the liquid bridges. However, the wetting state substantially affects the internal Marangoni effect dynamics and the Stefan advection dynamics due to its explicit influence on the nonuniform evaporative flux along the liquid–vapor interface. Between superhydrophobic confinements, the contact lines are confined in the wedge-shaped region, thereby locally augmenting the vapor concentration. As a result, the large evaporative flux near the bulge region develops a higher temperature gradient, thereby inducing upscaled thermal Marangoni flow compared to hydrophilic confinements. These findings may have significant implications for the ...

العلاقة: https://figshare.com/articles/journal_contribution/External_Stefan_and_Internal_Marangoni_Thermo-Fluid_Dynamics_for_Evaporating_Capillary_Bridges/25299790Test

الإتاحة: https://doi.org/10.1021/acs.langmuir.3c03703.s001Test
https://figshare.com/articles/journal_contribution/External_Stefan_and_Internal_Marangoni_Thermo-Fluid_Dynamics_for_Evaporating_Capillary_Bridges/25299790Test