MEMS Testbed for Mechanical Testing of Nanowires

Microelectromechanical Systems ◽

10.1115/imece2005-81987 ◽

2005 ◽

Author(s):

A. A. Desai ◽

M. A. Haque ◽

P. C. Eklund

Keyword(s):

Elastic Modulus ◽

Mechanical Testing ◽

Zno Nanowires ◽

Test Bed ◽

One Dimensional ◽

Post Buckling ◽

Mems Device ◽

Slender Columns ◽

Very High

In this paper, we present a MEMS test bed for electromechanical testing of nanowires and nanotubes. The MEMS device exploits the mechanics of post buckling deformation of slender columns to achieve very high force and displacement resolution. The proposed technique involves manipulating the nanowire or nanotube to the device site and hence is applicable to any type of one-dimensional solid. Initial experiments on semiconducting ZnO nanowires estimated the elastic modulus to be 1 GPa.

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Size Scale Effect on Generated Electric Potential of Nano Composite Electrical Generators

Volume 8: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2012-85590 ◽

2012 ◽

Author(s):

Kasra Momeni

Keyword(s):

Elastic Modulus ◽

Scale Effect ◽

Electric Potential ◽

Zno Nanowires ◽

Surface Model ◽

Multiscale Approach ◽

Nano Composite ◽

Size Scale ◽

Cylindrical Coordinate ◽

Axisymmetric Configuration

A multiscale approach is pursued for modeling the size-scale effect on generated electric potential by nanocomposite electrical generators of ZnO nanowires. A core-surface model is used for capturing the effect of size-scale on elastic modulus of ZnO NWs. In this model, a surface with different elastic modulus as of the core of NW was considered. Using linear elasticity and axisymmetric configuration of this problem, closed form governing equations are derived in cylindrical coordinate system. Parametric studied are performed for sample cases to demonstrate application of the developed model. It is shown that ZnO nanowires with larger aspect ratio and smaller diameters have higher performance and can produce higher electric potential.

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Study on the Dynamic Performance of Asphalt Concrete under Passive Confined Pressure

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.226-228.1755 ◽

2012 ◽

Vol 226-228 ◽

pp. 1755-1759

Author(s):

Hua Zhang ◽

Fei Li ◽

Yu Wei Gao

Keyword(s):

Elastic Modulus ◽

Asphalt Concrete ◽

Poisson Ratio ◽

Dynamic Properties ◽

Dynamic Performance ◽

Dynamic Strength ◽

Confining Pressure ◽

Mechanical Behaviors ◽

One Dimensional ◽

Stress States

An improved passive confining pressure SHPB method was used to study the dynamic mechanical behaviors of asphalt concrete under quasi-one dimensional strain state. The effect of confining jacket material and its geometrical sizes on the confining pressure were discussed. The dynamic strength, dynamic modulus of elasticity and dynamic Poisson ratio of asphalt concrete were obtained. The influential rules of confining pressure on the dynamic properties were studied by comparing the stress-strain curves of asphalt concrete under different stress states. The study found that passive confining greater impact on the strength of asphalt concrete than elastic modulus and Poisson ratio, but the elastic modulus improved with the increase of confining pressure.

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Slip band formation and crack initiation during very high cycle fatigue of duplex stainless steel – Part 1: Mechanical testing and microstructural investigations

Fatigue of Materials at Very High Numbers of Loading Cycles ◽

10.1007/978-3-658-24531-3_5 ◽

2018 ◽

pp. 95-110

Author(s):

T. Waurischk ◽

M. Söker ◽

A. Giertler ◽

N. Schönhoff ◽

M. Galster ◽

...

Keyword(s):

Stainless Steel ◽

Crack Initiation ◽

Duplex Stainless Steel ◽

Mechanical Testing ◽

Slip Band ◽

Steel Part ◽

Band Formation ◽

Very High Cycle Fatigue ◽

Stainless Steel Part ◽

Very High

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Comparative analysis of early divergent land plants and construction of DNA tools for hyper-expression in Marchantia chloroplasts

10.1101/2020.11.27.401802 ◽

2020 ◽

Author(s):

Eftychios Frangedakis ◽

Fernando Guzman-Chavez ◽

Marius Rebmann ◽

Kasey Markel ◽

Ying Yu ◽

...

Keyword(s):

Gene Expression ◽

Binding Sites ◽

Protein Production ◽

Marchantia Polymorpha ◽

Pentatricopeptide Repeat ◽

Test Bed ◽

High Ploidy ◽

Post Transcriptional Regulation ◽

Very High ◽

Rapid Transformation

ABSTRACTChloroplast genes are present at high ploidy in plants, and capable of driving very high levels of gene expression if mRNA production and stability are properly regulated. Marchantia polymorpha is a simple model plant that allows rapid transformation studies, however post-transcriptional regulation in plastids is poorly characterized in this liverwort. We have mapped patterns of transcription in Marchantia chloroplasts. Furthermore, we have obtained and compared sequences from 51 early-divergent plant species, and identified putative sites for pentatricopeptide repeat protein binding that are thought to play important roles in mRNA stabilisation. Candidate binding sites were tested for their ability to confer high levels of reporter gene expression in Marchantia chloroplasts, and levels of protein production and effects on growth were measured in homoplasmic transformed plants. We have produced novel DNA tools for protein hyper-expression in a facile plant system that is a test-bed for chloroplast engineering.

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A Novel Latching Relay Fabricated Using an Oxide Molded Tungsten Process

MRS Proceedings ◽

10.1557/proc-872-j11.6 ◽

2005 ◽

Vol 872 ◽

Author(s):

J.G. Fleming ◽

Michael Baker ◽

David Luck

Keyword(s):

Chemical Vapor Deposition ◽

Low Temperature ◽

Tensile Stress ◽

Vapor Deposition ◽

Chemical Mechanical Polishing ◽

Chemical Vapor ◽

Metal Contacts ◽

Cmos Compatible ◽

Mems Device ◽

Very High

AbstractIn this paper we describe an oxide molded tungsten process applied to the fabrication of a novel latching relay. The steps in the process are: deposition of a sacrificial oxide, patterning of the oxide, filling of the resulting mold with a blanket film of tungsten using chemical vapor deposition (CVD), and then the removal and planarization of excess tungsten through chemical mechanical polishing (CMP). The process for the incorporation of dielectric isolation has also been developed. The resulting tungsten structures are under high tensile stress, which appears to be compensated in process by the compressive stress of the oxide mold. All the steps are low temperature and the entire process is backend CMOS compatible. This process has been used to fabricate a latching relay which relies on the internal stress of the tungsten and always generates force in a pulling mode. Parts have been successfully fabricated and tested, the devices generate very high forces for a MEMS device and give reasonable contact resistances even without noble metal contacts.

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TOPoS

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834375 ◽

2018 ◽

Vol 620 ◽

pp. A187 ◽

Cited By ~ 3

Author(s):

P. François ◽

E. Caffau ◽

P. Bonifacio ◽

M. Spite ◽

F. Spite ◽

...

Keyword(s):

Thermodynamic Equilibrium ◽

Neutron Capture ◽

Local Thermodynamic Equilibrium ◽

Early Evolution ◽

One Dimensional ◽

Giant Stars ◽

Medium Resolution ◽

Calcium Iron ◽

Significant Spread ◽

Very High

Context. Extremely metal-poor stars are keys to understand the early evolution of our Galaxy. The ESO large programme TOPoS has been tailored to analyse a new set of metal-poor turn-off stars, whereas most of the previously known extremely metal-poor stars are giant stars. Aims. Sixty five turn-off stars (preselected from SDSS spectra) have been observed with the X-shooter spectrograph at the ESO VLT Unit Telescope 2, to derive accurate and detailed abundances of magnesium, silicon, calcium, iron, strontium and barium. Methods. We analysed medium-resolution spectra (R ≃ 10 000) obtained with the ESO X-shooter spectrograph and computed the abundances of several α and neutron-capture elements using standard one-dimensional local thermodynamic equilibrium (1D LTE) model atmospheres. Results. Our results confirms the super-solar [Mg/Fe] and [Ca/Fe] ratios in metal-poor turn-off stars as observed in metal-poor giant stars. We found a significant spread of the [α/Fe] ratios with several stars showing subsolar [Ca/Fe] ratios. We could measure the abundance of strontium in 12 stars of the sample, leading to abundance ratios [Sr/Fe] around the Solar value. We detected barium in two stars of the sample. One of the stars (SDSS J114424−004658) shows both very high [Ba/Fe] and [Sr/Fe] abundance ratios (>1 dex).

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Structure, Process, and Material Influences for 3D Printed Lattices Designed With Mixed Unit Cells

Volume 11A: 46th Design Automation Conference (DAC) ◽

10.1115/detc2020-22575 ◽

2020 ◽

Author(s):

Gabriel Briguiet ◽

Paul F. Egan

Keyword(s):

Elastic Modulus ◽

Mechanical Testing ◽

Mechanical Response ◽

Cell Types ◽

Unit Cell ◽

Ultraviolet Curing ◽

Mechanical Responses ◽

Lattice Design ◽

Unit Cells ◽

3D Printed

Abstract Emerging 3D printing technologies are enabling the design and fabrication of novel architected structures with advantageous mechanical responses. Designing complex structures, such as lattices, with a targeted response is challenging because build materials, fabrication process, and topological design have unique influences on the structure’s mechanical response. Changing any factor may have unanticipated consequences, even for simpler lattice structures. Here, we conduct mechanical compression experiments to investigate varied lattice design, fabrication, and material combinations using stereolithography printing with a biocompatible polymer. Mechanical testing demonstrates that a higher ultraviolet curing time increases elastic modulus. Material testing demonstrated that anisotropy does not strongly influence lattice mechanics. Designs were altered by comparing homogenous lattices of single unit cell types and heterogeneous lattices that combine two types of unit cells. Unit cells for heterogeneous structures include a Cube design for a high elastic modulus and Cross design for improved shear response. Mechanical testing of three heterogeneous layouts demonstrated how unit cell organization influences mechanical outcomes, therefore enabling the tuning of an elastic modulus that surpasses the law of averages designed for application-dependent mechanical needs. These findings provide a foundation for linking design, process, and material for engineering 3D printed structures with preferred properties, while also facilitating new directions in design automation and optimization.

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Path-conservative central-upwind schemes for nonconservative hyperbolic systems

ESAIM Mathematical Modelling and Numerical Analysis ◽

10.1051/m2an/2018077 ◽

2019 ◽

Vol 53 (3) ◽

pp. 959-985 ◽

Cited By ~ 2

Author(s):

Manuel Jesús Castro Díaz ◽

Alexander Kurganov ◽

Tomás Morales de Luna

Keyword(s):

Hyperbolic Systems ◽

Bottom Topography ◽

Nonlinear Partial Differential Equations ◽

Water System ◽

Upwind Scheme ◽

One Dimensional ◽

Upwind Schemes ◽

Shallow Water System ◽

Nonconservative Hyperbolic Systems ◽

Very High

We develop path-conservative central-upwind schemes for nonconservative one-dimensional hyperbolic systems of nonlinear partial differential equations. Such systems arise in a variety of applications and the most challenging part of their numerical discretization is a robust treatment of nonconservative product terms. Godunov-type central-upwind schemes were developed as an efficient, highly accurate and robust ``black-box’’ solver for hyperbolic systems of conservation and balance laws. They were successfully applied to a large number of hyperbolic systems including several nonconservative ones. To overcome the difficulties related to the presence of nonconservative product terms, several special techniques were proposed. However, none of these techniques was sufficiently robust and thus the applicability of the original central-upwind schemes was rather limited. In this paper, we rewrite the central-upwind schemes in the form of path-conservative schemes. This helps us (i) to show that the main drawback of the original central-upwind approach was the fact that the jump of the nonconservative product terms across cell interfaces has never been taken into account and (ii) to understand how the nonconservative products should be discretized so that their influence on the numerical solution is accurately taken into account. The resulting path-conservative central-upwind scheme is a new robust tool for both conservative and nonconservative hyperbolic systems. We apply the new scheme to the Saint-Venant system with discontinuous bottom topography and two-layer shallow water system. Our numerical results illustrate the good performance of the new path-conservative central-upwind scheme, its robustness and ability to achieve very high resolution.

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