Static Interface Research Articles

Influence of mini-screw diameter and loading conditions on static and dynamic assessments of bone-implant contact: An animal study.

The goal was to compare static versus dynamic bone-implant interface histology of mini-screws and to evaluate its relation to diameter and load. Canine animal model. Custom-machined, titanium alloy (Ti6AI4V) mini-screws (n=70) of 1.60, 2.00, 3.00 and 3.75mm diameter were placed into edentulous sites in five skeletally mature beagle dogs. Using a split-mouth design, no load (NL) was applied to one side while a 2N load (L) was applied by calibrated coil springs on the other side. Intravenous bone labels were administered 21 and 7days prior to sacrifice. Dogs were euthanized 90days after screw placement. Bone sections were analysed under bright-field and epifluorescent light. The region of interest was defined as the bone within the threads of the screws. The following parameters were quantified: (a) Static-bone volume/tissue volume (BV/TV %) and bone-implant contact (BIC, %); (b) Dynamic-labelled bone/bone volume (LB/BV, %), and dynamic BIC (DBIC, %). BV/TV ranged from 71.2% to 85.0% of the screw surface. BIC ranged from 45.7% to 55.4% of the screw surface and was not affected by diameter (P=0.66). In contrast, the percentage of DBIC did not vary with the applied load (P=0.41); however, it correlated significantly with the diameter of the screw (P=0.001). The percentage of DBIC that is actively remodelling increases with increasing diameter of the screw. Dynamic histomorphometry is more sensitive to detecting changes in bone-implant contact when compared to static measurements.

A Surface Connectivity-Based Approach for Leakage Channel Prediction in Static Sealing Interface

Leakage susceptibility is significant for the functionalization of engineering products, and surface topography plays a crucial role in forming the leakage channel in static sealing interface. This paper proposes a surface connectivity-based approach to predict the leakage channel in static sealing interface. The proposed approach consists of three modules including contact surface generation, leakage parameters definition, and leakage channel prediction. A high-definition metrology (HDM) instrument is adopted to measure the three-dimensional (3D) surface. The contact surface that can be considered as the sealing interface is generated by assembling the virtual gasket surface and waviness surface. Considering the spatial connectivity, two kinds of leakage parameters including connectivity parameters and correlation parameters are proposed to describe the characteristics of the contact surface. Meantime, a novel prediction algorithm is developed to directly indicate the potential leakage channel of the surface. Experimental results demonstrate that the proposed approach is valid to be accurate and effective, which can provide valuable information for surface topography and static sealing performance.

Research on the characteristic of noise and pressure fluctuation in the oil-gas mixing transportation of screw-axial pump

In order to study the spiral gas-liquid mixing loss and noise characteristics of the oil-gas mixing transportation of screw-axial pump, with the oil-gas mixing transportation of screw-axial pump as the research object, based on the RNG k–ε psilon internal unsteady flow model to simulate the pump parameter change of gas and liquid delivery information, extract the unsteady gas-liquid transfer information parameters and pressure fluctuation signals, using acoustic software LMS Virtual Lab IBEM indirect boundary element method is used to solve the helical axial multiphase mixture pumps in dipole source caused by noise. The distribution law of pressure field, pressure pulsation and sound pressure level in the pump and outlet of the helical axial flow multiphase flow pump is analyzed. The results show that the gas-liquid mixing in the helical-axial-flow oil-gas mixing pump, from impeller inlet to impeller outlet, is aggravated, the pressure increases and the flow is turbulent. From the inlet of the guide vane to the exit of the guide vane, the bubbles gradually move from the hub to the middle of the runner, then the pressure gradually decreases, and the low voltage area leads to the vortex phenomenon; for the internal pressure fluctuation of helical axial flow type oil-gas mixing pump, the pressure gradient in the static and static interference area between the impeller and the guide blade is large, which is an important area affecting hydraulic performance. The pressure pulsation in the cascade is affected by the blade passing frequency and the mutual interference between the rotor and stator blades. The pressure pulsation maximum value is mainly corresponding to the blade frequency and its doubling frequency, and under the interaction of rotor - stator cascade, the pressure pulsation of the monitoring point near the static and static interface is superimposed, and the main frequency is the blade’s triple leaf frequency. For screw axial flow noise in the oil-gas mixture pumps, screw axial multiphase flow pump hydrodynamic noise exports more than imports, sound pressure level frequency in low frequency band is evident, for impeller pressure impulses and its frequency doubling, after three times the pressure impulses, sound pressure level decline slows, the distribution of sound pressure level along with the increase of flow rate, shows the tendency of increase after decreases first. The research results are of great theoretical value and practical significance for the unsteady turbulent gas-liquid mixed transport, pressure fluctuation and noise characteristics in the oil-gas mixed transport pump.

Stability of the interface between two thin liquid layers under tangential high frequency vibrations

In this paper, a system of two equally thin layers of immiscible incompressible isothermal ideal liquids under high frequency horizontal harmonic vibrations is considered theoretically. The vessel containing the liquids is assumed to be closed, of rectangular form with weakly-deformable side borders and infinitely long in horizontal direction. Previous studies showed that, for significantly thin layers, the main instability in the system, oscillatory Kelvin-Helmholtz instability, should be the long-wave instability. Therefore, the problem was solved analytically using “shallow water” approximation. For all equations, a formal expansion with respect to two small parameters was used: one associated with a small ratio of the vertical to horizontal scale and another with small perturbations of the flat interface. Evolutionary equations were derived for the interface in the main order of expansion for vibration intensity less than a threshold value for oscillatory Kelvin-Helmholtz instability (subcritical area). The solutions found for these evolutionary equations correspond to traveling waves with soliton or cnoidal interfacial surface. The soliton profile is a limiting case of the cnoidal profile. The maximum speed of these waves was determined. It was demonstrated that the obtained solutions exist only in the subcritical area of parameters and from the critical level subcritical bifurcation emerges. For special case of traveling waves in a quasi-stationary mode (i.e. with static interface) also referred to as a “frozen wave”, a numerical analysis of linear stability was performed using a Fourier series expansion in a horizontal coordinate. The instability of quasi-stationary modes to small disturbances was demonstrated.

Toward an Atomistic Understanding of Solid-State Electrochemical Interfaces for Energy Storage

Veronica Augustyn is an Assistant Professor of Materials Science & Engineering at North Carolina State University. She received her PhD from the University of California, Los Angeles (2013) and was a Postdoctoral Fellow at the University of Texas at Austin (2013–2015). Her research is focused on the synthesis and characterization of materials operating at electrochemical interfaces, and in particular the relationships between material composition, structure, and morphology and the resulting electrochemical mechanisms. Recently, she was the recipient of a 2017 NSF CAREER Award and is a Scialog Fellow in Advanced Energy Storage at the Research Corporation for Science Advancement. Matthew McDowell is an assistant professor in the G.W. Woodruff School of Mechanical Engineering and the School of Materials Science and Engineering at the Georgia Institute of Technology. He received his PhD from Stanford University (2013) and was a postdoctoral scholar at Caltech from 2013 until 2015. His research is focused on understanding structural and chemical transformations in materials and at interfaces within electrochemical and electrical devices through the use of in situ and operando techniques. He has received the NSF CAREER Award, the AFOSR YIP Award, and the NASA Early Career Faculty Award and is a Scialog Fellow in Advanced Energy Storage. Aleksandra Vojvodic is Skirkanich Assistant Professor of Innovation in Chemical & Biomolecular Engineering at University of Pennsylvania. She received her PhD from Chalmers University of Technology, was Postdoc at Technical University of Denmark and Stanford University, and was Staff Scientist at SLAC National Accelerator Laboratory. Her research focuses on computational-driven materials design including studies of surfaces and interfaces of materials for chemical transformations, energy conversion, and storage. She received the 2017 European Federation of Catalysis Societies Young Researcher Award and the MIT Technology Review 35 Award 2016. She is a CIFAR Bio-Inspired Solar Energy fellow and a Scialog Fellow in Advanced Energy Storage.

Leakage Monitoring in Static Sealing Interface Based on Three Dimensional Surface Topography Indicator

Leakage directly affects the functional behavior of a product in engineering practice, and surface topography is one of the main factors in static seal to prevent leakage. This paper aims at monitoring the leakage in static sealing interface, using three-dimensional (3D) surface topography as an indicator. The 3D surface is measured by a high definition metrology (HDM) instrument that can generate millions of data points representing the entire surface. The monitoring approach proposes a series of novel surface leakage parameters including virtual gasket, contact area percentage (CAP), void volume (VV), and relative void volume (SWvoid) as indicators. An individual control chart is adopted to monitor the leakage surface of the successive machining process. Meantime, based on the Persson contact mechanics and percolation theory, the threshold of leakage parameter is found using finite element modeling (FEM). Experimental results indicate that the proposed monitoring method is valid to precontrol the machining process and prevent leakage occurring.

A combined theory model for predicting the viscosity of water-based Newtonian nanofluids containing spherical oxide nanoparticles

Viscosity plays a crucial role in the flow and heat transfer process of nanofluids. To effectively calculate and predict the changing characteristics of nanofluids viscosity, this study presents a theoretical model combining the static interface layer and dynamic Brownian motion mechanisms of spherical nanoparticles for water-based Newtonian nanofluids. The model describes the reasonable dependences of nanofluids viscosity on physical properties of nanoparticles (density, volume fraction, size) and base fluid (temperature, viscosity, density). Taking four kinds of typical water-based Newtonian nanofluids containing spherical oxide nanoparticles (Al2O3, CuO, SiO2 and TiO2) as examples, the prediction performance of different viscosity models is analyzed in detail. From the comparison studies, it is demonstrated that the new viscosity model developed in this paper can exhibit better prediction performance than many well-known theoretical models and empirical correlations. Not only do the predicted results of model agree well with the experimental data from various studies, but also the effects of different factors are reflected effectively.

A likelihood-free Bayesian derivation method for service variants

Application programming interfaces (API), allowing systems to be accessed by the services they expose, have proliferated on the Internet and gained strategic interest in the IT industry. However, integration opportunities for larger, enterprise systems are hampered by complex and overloaded operations of their interfaces, having hundreds of parameters and multiple levels of nesting, corresponding to multiple business entities. Static (code) analysis techniques have been proposed to analyse service interfaces of enterprise systems. They support the derivation of business entities and relationships from the parameters of interface operations, allowing the restructure of operations, based on individual entities. In this paper, we extend the repertoire of static interface analysis to derive service variants, whereby subsets of operation parameters correspond to multiple nested business entity subtypes of variants. Specifically, we apply a Monte Carlo sampling method, based on likelihood-free Bayesian sampling, to traverse large parameter spaces, based on higher probabilistic tree search, to efficiently find subsets of parameters related to prospective subtypes. The results demonstrate a method with significant success rates in massive search spaces, as applied to the FedEx Shipment interface whose operations have in excess of 1000 parameters.

Snell's law of elastic waves propagation on moving property interface of time-varying materials

In this work, Snell's law of elastic waves on the moving property interface (MPI) of time-varying materials has been studied. First, additional constraints of the elastic wave propagation on MPI are proposed to ensure self-consistence of Snell's law. Second, based on Huygens principle, a geometric approach is developed which can be used to geometrically reveal the wave propagation directions on MPI with clear geometric meanings for the additional constraints. Two criteria are proposed to determine the existence of reflected or transmitted wave on MPI. Finally, based on the two criteria, the conditions for the existence of reflected or transmitted waves are expressed by moving velocity of MPI and wave propagation velocities on both sides of MPI. Then, according to the number of reflected and transmitted waves as well as their polarization types, the propagation of elastic wave on MPI can be classified into 6 cases for SH wave incidence, 12 cases for SV wave incidence, and 15 cases for P wave incidence determined by moving velocity of MPI and wave propagation velocities on both sides of MPI. While, the traditional case of elastic wave propagation on a static material interface, i.e. 2 emitted waves for SH wave and 4 emitted waves for SV or P waves are special cases of elastic wave propagation on MPI. It is noted that for most propagation cases presented in this work, the propagation coefficients are unable to be solved with only the continuous conditions on MPI, i.e. the continuity of displacement, stress and momentum on MPI. This work indicates the elastic wave propagation on MPI can have multiple cases of emitted wave which may provide useful insights for further studying elastodynamics of time-varying materials.

Interface damage model for fatigue-driven fracture

A fatigue interface damage model is presented that is based on combining a fatigue evolution law with a static interface damage model. The fatigue model elegantly enables the simulation of crack initiation and propagation in a computationally efficient and accurate way, accounting for mixed-mode loading conditions and fatigue loading of variable amplitude. The main features of the fatigue model are explained and demonstrated by means of an illustrative numerical example.

Three dimensional wave propagation in time-varying materials: A mathematical model based on the weak solutions of continuity in the moving property interface

Abstract In this work, the elastic wave propagation through the moving property interface (MPI) in time-varying materials has been investigated. First, a general description of the MPI in time-varying materials has been given. Then, the elastic wave propagation through MPI has been systematically explored. In general, the wave propagation behaviors through MPI can be divided into two types depending on moving velocity of MPI and incident angle. For the first type, it has similar wave propagation behavior of that in static property interface, that is the reflection and refraction waves can be determined by the displacement and stress continuity in MPI. While, for the second type, it may have two transmitted waves, or only one transmitted wave or one reflected wave. Therefore, the transmitted waves or reflected wave cannot be solved by the commonly used continuous conditions, i.e. the displacement and stress continuities in MPI, due to the over constrained or under constrained problem. In order to deal with the wave propagation through MPI, a novel mathematical model is proposed based on the weak form of continuity in MPI. The results have shown that the wave propagation coefficients depend on not only the wave impedance radio and incident angle, but also the moving velocity of MPI. Besides, the transmitted and reflected wave frequencies and wavelengths are also significantly influenced by the moving velocity of MPI. When MPI catches up or exceeds the reflected or transmitted waves, the wavelength of the reflected or transmitted waves degenerates to zero, so that a shock wave is found in MPI and the displacements at the two sides of MPI are discontinuous. The wave propagation behaviors across MPI are further simulated via COMSOL Multiphysics software which shows very good agreement with the theoretical predictions. Moreover, the energy balance of SH waves in MPI is discussed. This work indicates that the novel mathematical model proposed in this paper is applicable to high dimensional wave phenomenon with moving boundaries, and is capable for studying complex wave equations, especially for wave equations with moving boundaries.

Interfacial undercooling in solidification of colloidal suspensions: analyses with quantitative measurements.

Interfacial undercooling in the complex solidification of colloidal suspensions is of significance and remains a puzzling problem. Two types of interfacial undercooling are supposed to be involved in the freezing of colloidal suspensions, i.e., solute constitutional supercooling (SCS) caused by additives in the solvent and particulate constitutional supercooling (PCS) caused by particles. However, quantitative identification of the interfacial undercooling in the solidification of colloidal suspensions, is still absent; thus, the question of which type of undercooling is dominant in this complex system remains unanswered. Here, we quantitatively measured the static and dynamic interface undercoolings of SCS and PCS in ideal and practical colloidal systems. We show that the interfacial undercooling primarily comes from SCS caused by the additives in the solvent, while PCS is minor. This finding implies that the thermodynamic effect of particles from the PCS is not the fundamental physical mechanism for pattern formation of cellular growth and lamellar structure in the solidification of colloidal suspensions, a general case of ice-templating method. Instead, the patterns in the ice-templating method can be controlled effectively by adjusting the additives.

A Lagrangian-Eulerian advection scheme with moment-of-fluid interface reconstruction

ABSTRACTA Lagrangian–Eulerian advection scheme (LEAS) with Moment-of-Fluid (MoF) interface reconstruction is presented for interfacial flows. In MoF method, in addition to the volume fraction field, material centroid is used for interface reconstruction. Physically material centroid indicates the material location inside a mixed cell. Therefore, MoF method reconstructs linear interfaces exactly and is second order accurate for curved interfaces. Despite being second order accurate for static interface reconstruction, MoF reconstruction is inaccurate when centroid is not properly advected. An accurate centroid advection method based on Barycenter of centroid is discussed here. A comparison of this centroid advection with the pure Lagrangian advection based on Runge–Kutta integrator is demonstrated for two different advection tests. The superiority of MoF is established by comparing the volume error norm with other interface reconstructions. Significant improvement in accuracy is observed when LEAS material advection is used in conjuction with accurate centroid advection for MoF reconstruction.

On the Phase Transition Characteristic of Static Sealing Interface Based on Lattice Leakage Model

On the Phase Transition Characteristic of Static Sealing Interface Based on Lattice Leakage Model

Entropic lattice Boltzmann method for multiphase flows: Fluid-solid interfaces.

The recently introduced entropic lattice Boltzmann model (ELBM) for multiphase flows [A. Mazloomi M., S. S. Chikatamarla, and I. V. Karlin, Phys. Rev. Lett. 114, 174502 (2015)] is extended to the simulation of dynamic fluid-solid interface problems. The thermodynamically consistent, nonlinearly stable ELBM together with a polynomial representation of the equation of state enables us to investigate the dynamics of the contact line in a wide range of applications, from capillary filling to liquid drop impact onto a flat surfaces with different wettability. The static interface behavior is tested by means of the liquid column in a channel to verify the Young-Laplace law. The numerical results of a capillary filling problem in a channel with wettability gradient show an excellent match with the existing analytical solution. Simulations of drop impact onto both wettable and nonwettable surfaces show that the ELBM reproduces the experimentally observed drop behavior in a quantitative manner. Results reported herein demonstrate that the present model is a promising alternative for studying the vapor-liquid-solid interface dynamics.

Interfacial deformation and jetting of a magnetic fluid

An attractive technique for forming and collecting aggregates of magnetic material at a liquid–air interface by an applied magnetic field gradient was recently proposed, and its underlying principle was studied theoretically and experimentally (Tsai et al., 2013): when the magnetic field is weak, the deflection of the liquid–air interface has a steady shape, while for sufficiently strong fields, the interface destabilizes and forms a jet that extracts magnetic material. Motivated by this work, we develop a numerical model for the closely related problem of solving two-phase Navier–Stokes equations coupled with the static Maxwell equations. We computationally model the forces generated by a magnetic field gradient produced by a permanent magnet and so determine the interfacial deflection of a magnetic fluid (a pure ferrofluid system) and the transition into a jet. We analyze the shape of the liquid–air interface during the deformation stage and the critical magnet distance for which the static interface transitions into a jet. We draw conclusions on the ability of our numerical model to predict the large interfacial deformation and the consequent jetting, free of fitting parameters.

Online product experiences: The effect of simulating stroking gestures on product understanding and the critical role of user control

This article builds upon the persuasiveness of touch in consumer settings, extending it to an online store environment. Recognizing that actual touch is not always feasible, the aim is to investigate whether interactive visual stimuli can tap into tactile perceptual information, thus improving understanding (i.e., perceived diagnosticity) regarding product attributes in an online store. In Study 1, an interface with image interactivity to simulate stroking gestures increased perceived diagnosticity of the experience attributes of a product (i.e., a scarf), as compared to a static interface using only pictures. Mediation analysis indicates that this effect is due to visually induced tactile sensations. As expected, no effects were found for search attributes, for which touch is considered less diagnostic. Study 2 reaffirms the importance of tactile sensations in perceived diagnosticity regarding experience attributes using a different product (i.e., a throw blanket), in addition to indicating the crucial importance of user control in invoking tactile sensations. In other words, Study 2 demonstrates that the ability to control the online product (instead of merely watching the product being moved around) is important to induce tactile sensations. Results from both studies indicate that, in the context of online stores, simulated tactile sensations is an important factor in online product understanding.

Nucleation and Growth of Ordered Copolymer Structures at Reactive Interfaces between PA6 and MA-g-HDPE

We have studied the effect of the interfacial chemical reaction between PA6 and MA-g-HDPE in static conditions at a macroscopically flat interface. Interface destabilization and the growth of instabilities, somehow similar to myelin figures observed in surfactants put in the presence of water, are observed. For the first time in this system, it is shown that ordered microphase-separated copolymer domains, whose morphologies depend on the architecture of the copolymer, namely, essentially on the relative length of the blocks on each side of the interface, may nucleate and grow at a static interface between reactive polymers. We discuss the stability of the plane interface in the case of nonsymmetrical formed graft copolymers. The density of copolymers in the interface (coverage) can be estimated accurately from the long period of the formed structures. We confirm the predictions of Berezkin et al. This observation is very important since it confirms that nanometric domains are certainly generated during reactive extrusion, in addition to micrometric domains formed by rheological processes.

Physical and numerical modelling of dry granular flows under Coriolis conditions

In this paper, quantitative observations of dry granular flows subject to varying magnitude and direction of Coriolis acceleration are presented in order to assess the robustness of the Savage–Hutter shallow water approximation of granular flow for modelling landslides. Nine tests carried out at 70° and 45° slope inclinations are described for cases where no Coriolis acceleration was applied (i.e. tests performed at 1g), and where the Coriolis acceleration acted into or out of the slope (centrifuge tests). Given that the magnitude of the Coriolis term is velocity dependent, each point within a model landslide on the centrifuge experienced a unique time and space-varying magnitude of Coriolis acceleration, altering the flow displacement with time and final deposit characteristics. The resultant behaviour is compared to a depth-averaged flow model based on a frictional rheology. A single set of model parameters was found to be appropriate for all test conditions and directions/magnitudes of Coriolis acceleration, illustrating the robustness of the frictional depth-averaged approach to capture the mobility of dry granular flows, albeit as a ‘Class C' type of prediction. It is noted that the empirically derived basal interface friction was found to be lower than the static interface friction determined by conventional testing, suggesting that new methods are needed for the a priori determination of suitable rheological parameters for high-speed flows.

Generic System for Human-Computer Gesture Interaction: Applications on Sign Language Recognition and Robotic Soccer Refereeing

Hand gestures are a powerful way for human communication, with lots of potential applications in the area of human computer interaction. Vision-based hand gesture recognition techniques have many advantages compared with traditional devices, giving users a simpler and more natural way to communicate with electronic devices. This work proposes a generic system architecture based in computer vision and machine learning, able to be used with any interface for real-time human-machine interaction. Its novelty is the integration of different tools for gesture spotting and the proposed solution is mainly composed of three modules: a pre-processing and hand segmentation module, a static gesture interface module and a dynamic gesture interface module. The experiments showed that the core of vision-based interaction systems could be the same for all applications and thus facilitate the implementation. For hand posture recognition, a SVM (Support Vector Machine) model was trained with a centroid distance dataset composed of 2170 records, able to achieve a final accuracy of 99.4 %. For dynamic gestures, an HMM (Hidden Markov Model) model was trained for each one of the defined gestures that the system should recognize with a final average accuracy of 93.7 %. The datasets were built from four different users with a total of 25 gestures per user, totalling 1100 records for model construction. The proposed solution has the advantage of being generic enough with the trained models able to work in real-time, allowing its application in a wide range of human-machine applications. To validate the proposed framework two applications were implemented. The first one is a real-time system able to interpret the Portuguese Sign Language. The second one is an online system able to help a robotic soccer game referee judge a game in real-time.