Three-dimensional nonlocal-surface energy-based statics, dynamics, and divergence instability of movable cable-like nanostructures with arbitrary translational motion

2021 ◽  
Author(s):  
Keivan Kiani ◽  
Mahdi Efazati
Keyword(s):  
Surface Energy ◽  
Translational Motion ◽  
Three Dimensional ◽  
Divergence Instability

Biomechanical characteristics of C1–2 cable fixations

1996 ◽  
Vol 85 (2) ◽  
pp. 316-322 ◽  
Author(s):  
Curtis A. Dickman ◽  
Neil R. Crawford ◽  
Christopher G. Paramore
Keyword(s):  
Cyclic Loading ◽  
Translational Motion ◽  
Biomechanical Testing ◽  
Three Dimensional ◽  
Constrained Motion ◽  
Content Type ◽  
Physiological Range ◽  
Fixation Techniques ◽  
Cable Fixation ◽  
Fine Print

✓ The biomechanical characteristics of four different methods of C1–2 cable fixation were studied to assess the effectiveness of each technique in restoring atlantoaxial stability. Biomechanical testing was performed on the upper cervical spines of four human cadaveric specimens. Physiological range loading was applied to the atlantoaxial specimens and three-dimensional motion was analyzed with stereophotogrammetry. The load–deformation relationships and kinematics were measured, including the stiffness, the angular ranges of motion, the linear ranges of motion, and the axes of rotation. Specimens were nondestructively tested in the intact state, after surgical destabilization, and after each of four different methods of cable fixation. Cable fixation techniques included the interspinous technique, the Brooks technique, and two variants of the Gallie technique. All specimens were tested immediately after fixation and again after the specimen was fatigued with 6000 cycles of physiological range torsional loading. All four cable fixation methods were moderately flexible immediately; the different cable fixations allowed between 5° and 40° of rotational motion and between 0.6 and 7 mm of translational motion to occur at C1–2. The Brooks and interspinous methods controlled C1–2 motion significantly better than both of the Gallie techniques. The motion allowed by one of the Gallie techniques did not differ significantly from the motion of the unfixed destabilized specimens. All cable fixation techniques loosened after cyclic loading and demonstrated significant increases in C1–2 rotational and translational motions. The bone grafts shifted during cyclic loading, which reduced the effectiveness of the fixation. The locations of the axes of rotation, which were unconstrained and mobile in the destabilized specimens, became altered with cable fixation. The C1–2 cables constrained motion by shifting the axes of rotation so that C-1 rotated around the fixed cable and graft site. After the specimen was fatigued, the axes of rotation became more widely dispersed but were usually still localized near the cable and graft site. Adequate healing requires satisfactory control of C1–2 motion. Therefore, some adjunctive fixation is advocated to supplement the control of motion after C1–2 cable fixation (that is, a cervical collar, a halo brace, or rigid internal fixation with transarticular screws).

Precisely Controlling Assembly Angle of Surface Tension Powered Self-Assembly for MEMS Microstructures

2007 ◽  
Author(s):  
Kai-Lin Pan ◽  
Yi-Lin Yan ◽  
Bin Zhou
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Self Assembly ◽  
Current Model ◽  
Three Dimensional ◽  
Design Parameters ◽  
Solder Paste ◽  
Surface Evolver ◽  
Final Assembly ◽  
The Relationship

How to integrate the microstructures which are made by various micro manufacturing methods into a functional system or device is the key to the application of MEMS technology. Solder self-assembly is based on surface tension with the properties of “self-organization”, low cost, batch processes and the compatibility with surface mount technology, which makes it be a challenging alternate technique. Solder self-assembly is based on the principle of surface energy minimization of molten solder material. During the process of minimizing the surface energy, surface tension can pull the horizontal hinged or hingeless plate up to a particular angle to achieve the minimal system energy. Finite element method is applied in this paper. MEMS self-assembly three-dimensional dynamic simulation model is developed by SURFACE EVOLVER. First, the model in this paper dynamically simulate the angle change of hinged plate during the process of evolvement of solder; second, the comparisons among the results from the current model and those from analytical two-dimensional model and three-dimensional static model are carried out; third, through Design of Experiments (DoE) with the application of the current model, the influences of design parameters such as pad size, pad geometry, and solder paste volume to the assembly angle are compared and discussed. Through changing the pad size, pad geometry and solder paste volume in SURFACE EVOLVER model, the corresponding final assembly angel from dynamic three-dimensional models are obtained. The relationship between design parameters to the assembly angle is concluded by the application of statistical analyses. The final angle can be controlled more effectively through synthetically optimize these parameters. It can provide effective guidance to the practical manufacturing of MEMS. Further research should focuses on the MEMS self-assembly experiment to intensively understand the relationship between the pad sizes, pad position, solder paste volume, hinge position, lock position and intermetallic compounds and the final assembly angle.

Aeroelastic Stability of Wide Webs and Narrow Ribbons in Cross Flow

2008 ◽  
Vol 75 (4) ◽  
Author(s):  
Rahul A. Bidkar ◽  
Arvind Raman ◽  
Anil K. Bajaj
Keyword(s):  
Three Dimensional ◽  
Cross Flow ◽  
Coupled System ◽  
Inviscid Fluid ◽  
Aeroelastic Stability ◽  
Aeroelastic Flutter ◽  
Panel Methods ◽  
Divergence Instability ◽  
Applied Tension ◽  
The Web

Aeroelastic flutter can lead to large amplitude oscillations of tensioned wide webs and narrow ribbons commonly used in the paper-handling, textile, sheet-metal, and plastics industries. In this article, we examine the aeroelastic stability of a web or a ribbon, which is submerged in an incompressible and inviscid fluid flow across its free edges. The web or ribbon is modeled as a uniaxially tensioned Kirchhoff plate with vanishingly small bending stiffness. A Galerkin discretization for the structural dynamics together with panel methods for the unsteady three dimensional potential flow are used to cast the coupled system into the form of a gyroscopic, nonconservative dynamical system. It is found that wide webs mainly destabilize through a divergence instability due to the cross-flow-induced conservative centrifugal effects. However, for certain values of applied tension, the wake-induced nonconservative effects can destabilize the web via a weak flutter instability. Contrarily, narrow ribbons in cross flow are nearly equally likely to undergo flutter or divergence instability depending on the value of applied tension.

scholarly journals A Novel High Efficiency Fractal Multiview Video Codec

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Shiping Zhu ◽  
Dongyu Zhao ◽  
Ling Zhang
Keyword(s):  
High Efficiency ◽  
Translational Motion ◽  
Three Dimensional ◽  
Rate Distortion ◽  
Spatial Prediction ◽  
Estimation Algorithm ◽  
Video Data ◽  
Video Codec ◽  
Disparity Estimation ◽  
Multiview Video

Multiview video which is one of the main types of three-dimensional (3D) video signals, captured by a set of video cameras from various viewpoints, has attracted much interest recently. Data compression for multiview video has become a major issue. In this paper, a novel high efficiency fractal multiview video codec is proposed. Firstly, intraframe algorithm based on the H.264/AVC intraprediction modes and combining fractal and motion compensation (CFMC) algorithm in which range blocks are predicted by domain blocks in the previously decoded frame using translational motion with gray value transformation is proposed for compressing the anchor viewpoint video. Then temporal-spatial prediction structure and fast disparity estimation algorithm exploiting parallax distribution constraints are designed to compress the multiview video data. The proposed fractal multiview video codec can exploit temporal and spatial correlations adequately. Experimental results show that it can obtain about 0.36 dB increase in the decoding quality and 36.21% decrease in encoding bitrate compared with JMVC8.5, and the encoding time is saved by 95.71%. The rate-distortion comparisons with other multiview video coding methods also demonstrate the superiority of the proposed scheme.

scholarly journals Multibody Dynamic Analysis of a Wind Turbine Drivetrain in Consideration of the Shaft Bending Effect and a Variable Gear Mesh Including Eccentricity and Nacelle Movement

2021 ◽  
Vol 8 ◽  
Author(s):  
Yonghui Park ◽  
Hyunchul Park ◽  
Zhe Ma ◽  
Jikun You ◽  
Wei Shi
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Gear Tooth ◽  
Translational Motion ◽  
Three Dimensional ◽  
Contact Forces ◽  
Dynamic Responses ◽  
Renewable Energy Resources ◽  
Gear Mesh ◽  
Direct Numerical Integration

Due to the energy crisis and global warming issues, the wind energy is becoming one of the most attractive renewable energy resources in the world. The drivetrains in the wind turbine tend to fail more prematurely than those in any other applications. Gearbox is the subsystem that causes the most downtime for the wind turbines. In the previous research, only the torsional flexibility of the shaft was considered in the drivetrain model. However, because the shaft is longer than other parts, and components connected by the shaft affect each other via shaft bending, the flexibility of the shaft cannot be ignored. In this study, a spherical joint that consists of three rotational springs was used to define the shaft bending. This shaft bending will affect the drivetrain rotation, the translational motion and the gear mesh contact force. Additionally, the eccentricity and the nacelle movement are analyzed due to the coupled motion. In this paper, a mathematical model of the drivetrain is proposed, which is a three-dimensional dynamic model that includes flexible bearings, a gear mesh model, shaft flexibility, eccentricity, and nacelle movement. The equation of motion of the drivetrain is derived using Lagrange's equation. The governing equation is solved numerically via direct numerical integration. The dynamic responses of the system and contact forces between the gear tooth in the time and frequency domains are calculated numerically. The study shows that this dynamic model of the drivetrain will be highly useful for subsequent studies on the wind turbine condition monitoring.

scholarly journals Surface Modification of Additively Manufactured Nitinol by Wet Chemical Etching

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7683
Author(s):  
Denis Nazarov ◽  
Aida Rudakova ◽  
Evgenii Borisov ◽  
Anatoliy Popovich
Keyword(s):  
Mechanical Properties ◽  
Free Surface ◽  
Surface Energy ◽  
Surface Composition ◽  
Three Dimensional ◽  
Physicochemical Characteristics ◽  
Contact Angles ◽  
Free Surface Energy ◽  
Flat Plates ◽  
Water Contact

Three-dimensional printed nitinol (NiTi) alloys have broad prospects for application in medicine due to their unique mechanical properties (shape memory effect and superplasticity) and the possibilities of additive technologies. However, in addition to mechanical properties, specific physicochemical characteristics of the surface are necessary for successful medical applications. In this work, a comparative study of additively manufactured (AM) NiTi samples etched in H2SO4/H2O2, HCl/H2SO4, and NH4OH/H2O2 mixtures was performed. The morphology, topography, wettability, free surface energy, and chemical composition of the surface were studied in detail. It was found that etching in H2SO4/H2O2 practically does not change the surface morphology, while HCl/H2SO4 treatment leads to the formation of a developed morphology and topography. In addition, exposure of nitinol to H2SO4/H2O2 and HCl/H2SO4 contaminated its surface with sulfur and made the surface wettability unstable in air. Etching in NH4OH/H2O2 results in surface cracking and formation of flat plates (10–20 microns) due to the dissolution of titanium, but clearly increases the hydrophilicity of the surface (values of water contact angles are 32–58°). The etch duration (30 min or 120 min) significantly affects the morphology, topography, wettability and free surface energy for the HCl/H2SO4 and NH4OH/H2O2 etched samples, but has almost no effect on surface composition.

INFLUENCE OF THE COPPER AND STEEL SURFACES’ ROUGHNESS ON SURFACE ENERGY AND WETTABILITY

2021 ◽  
Vol 7 (1) ◽  
pp. 60-76
Author(s):  
Anastasia G. Islamova ◽  
Dmitriy V. FEOKTISTOV ◽  
Evgeniya G. ORLOVA
Keyword(s):  
Heat Exchange ◽  
Surface Energy ◽  
Fundamental Problem ◽  
Three Dimensional ◽  
Heat Pipes ◽  
Polar Component ◽  
Shadow Method ◽  
Thermal Physics ◽  
Dipole Interactions ◽  
Steel Surfaces

This article aims at solving the fundamental problem of thermal physics. This problem includes controlling small volumes of liquids on the heat exchange surfaces of special devices (for example, thermosyphons and heat pipes) working in a closed evaporative-condensation cycle. The authors analyze the effect of roughness on surface energy and wettability of different textures on typical heat exchange surfaces made of copper and steel prepared for operation by mechanical (abrasive) processing. Six textures were created on the copper and steel surfaces using a grinding and polishing machine. The roughness of the textures was evaluated based on the analysis of three-dimensional roughness characteristics (amplitude and hybrid). The surface wettability was studied on the experimental setup with the shadow method. The surface free energy of abrasively processed surfaces was determined by the Owens—Wendt—Rabel—Kaelble method. The results show the necessity of using at least one three-dimensional amplitude and hybrid characteristics to evaluate the textures. The authors have determined the conditions for the formation of Gaussian and sinusoidal textures. A significant increase in surface area is achieved when copper and steel are processed with the abrasive discs with an average grit size of up to 100 μm. This increase is up to 7% for copper and up to 2.7%. After abrasive processing of copper and steel surfaces, the proportion of the polar component in their total surface energy changes. This is a consequence of changes in dipole interactions and hydrogen bonds between atoms.

A First Example: The “Particle in a Box“ and Quantized Translational Motion

2020 ◽  
pp. 59-96
Author(s):  
Jochen Autschbach
Keyword(s):  
Degrees Of Freedom ◽  
Separation Of Variables ◽  
Translational Motion ◽  
Three Dimensional ◽  
Potential Wells ◽  
Quantum Tunnelling ◽  
Atomic Force ◽  
Quantum Behavior ◽  
The One ◽  
Three Degrees Of Freedom

The simple ‘particle in a box’ (Piab) is introduced in this chapter so that the reader can get familiar with applying the quantum recipe and atomic units. The PiaB is introduced in its one, two, and three dimensional variants, which demonstrates the use of the separation of variables technique as a strategy to solve the Schrodinger equation for a particle with two or three degrees of freedom. It is shown that the confinement of the particle causes the energy to be quantized. The one-dimensional PiaB is then applied to treat the electronic spectra of cyanine dyes and their absorption colors. The chapter then introduces more general setups with finite potential wells, in order to introduce the phenomenon of quantum tunnelling and to discuss more generally with the unintuitive ‘quantum behavior’ of particles such as electrons. Scanning tunnelling and atomic force microscopes are also discussed briefly.

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