Afrikaaose Bybeivertaliogs: 'n Toekomsvisie

Stander, H.F.

doi:10.4102/ve.v22i2.658

Cited by 3 publications

(4 citation statements)

References 9 publications

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“…Thus depending on the polarity of the carriers in bulk graphene sheet a p-n junction or a p-p junction develops close to the metal/graphene interface. We have shown elsewhere [17,18] that the resistances associated with these junctions for opposite values of the charge density n in the sheet differ by an amount r nc (n)/w where r nc depends only on n c and on the length over which the density varies across the junction [19,20,21,22]. This is consistent with the observed positive R odd ; with n-type graphene below the contact one should observe a negative R odd .…”

supporting

confidence: 80%

Evidence of the role of contacts on the observed electron-hole asymmetry in graphene

et al. 2008

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We perform electrical transport measurements in graphene with several sample geometries. In particular, we design "invasive" probes crossing the whole graphene sheet as well as "external" probes connected through graphene side arms. The four-probe conductance measured between external probes varies linearly with charge density and is symmetric between electron and hole types of carriers. In contrast measurements with invasive probes give a strong electron-hole asymmetry and a sublinear conductance as a function of density. By comparing various geometries and types of contact metal, we show that these two observations are due to transport properties of the metal/graphene interface. The asymmetry originates from the pinning of the charge density below the metal, which thereby forms a p-n or p-p junction, depending on the polarity of the carriers in the bulk graphene sheet. Our results also explain part of the sublinearity observed in conductance as a function of density in a large number of experiments on graphene, which has generally been attributed to short-range scattering only.

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supporting

confidence: 80%

Evidence of the role of contacts on the observed electron-hole asymmetry in graphene

et al. 2008

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“…[14], and for the optimization procedure, see, e,g., Refs. [15,16], The procedure can be described as find C,, y,, Ö,, and O-Q mininiize «r = subjected to C,, y, and (To -0 and Qi -0…”

Section: (2)mentioning

confidence: 99%

Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures

Gustafsson

Moverare

Simonsson

et al. 2011

Journal of Engineering for Gas Turbines and Power

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Turbine di.'iks are of large importance to turbine designers as they are exposed to hot environment and subjected to high loads. In order to analyze such components with respect to fatigue crack initiation, the work generally starts with a rigorous analysis of the fttst few cycles, during which an important stre.ss redistribution will always take place in an inelastic structure. In this work, the nonlinear kinematic hardening law by Olmo and Wang (1998, "Constitutive Modeling of Cyclic Plasticity With Emphasis on Ratchetting. " Int. J. Mech. Sei., 40, has been used in combination with an i.sotropic softening law for describing the initial stress-.<¡train distribution for strain controlled uniaxial tests of the material Inconel 718. Focus has been placed on finding a simple model with few material parameters and to describe the initial .softening and the comparatively small mean stre.ss relaxation observed during the material testing. The simulation results obtained b\ using the model fit the experimental results welt.

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“…Thus, the response for an arbitrary design can subsequently be found using Equation (2). Obviously, the minimum number of function evaluations N,,, is equal to the number of unknown constants p,.…”

Section: Y = X -$mentioning

confidence: 99%

“…Application examples are found in e.g. Marklund and Nilsson [I], Stander et al [2] and Yamasaki and Han [3]. In the RSM the responses are approximated by polynomial expressions, which smoothen out the high freqence, noise of an impact event, and the gradients associated with the response surface can easily be calculated.…”

Section: Introductionmentioning

confidence: 99%

A method to determine structural sensitivities in vehicle crashworthiness design

Redhe¹,

Nilsson²

2002

International Journal of Crashworthiness

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~ The aim of this work is to determine when a linear surface approximation in the Response Surface Methodology can be utilised to calculate parameter sensitivities of a vehicle exposed to impact loading. Linear surface approximations are less costly than quadratic surfaces due to a lower number of function evaluations. However, the linear surface approximation error is often larger. Two structural impact problems are studied: one simple rail structure with two design variables and one vehicle model with ten design variables. The study has shown that linear surface approximations can be used to determine the order ofsensitivity. However. the absolute magnitudes of the sensitivities are not reliable. This can be used ifthe normalised root mean square error is smaller than 10 YO. NOTATIONS P,J:

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Afrikaaose Bybeivertaliogs: 'n Toekomsvisie

Cited by 3 publications

References 9 publications

Evidence of the role of contacts on the observed electron-hole asymmetry in graphene

Evidence of the role of contacts on the observed electron-hole asymmetry in graphene

Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures

A method to determine structural sensitivities in vehicle crashworthiness design

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