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Article
Publication date: 1 January 2004

Christianne V.D.R. Anderson and Kumar K. Tamma

We first provide an overview of some predominant theoretical methods currently used for predicting thermal conductivity of thin dielectric films: the equation of radiative…

2793

Abstract

We first provide an overview of some predominant theoretical methods currently used for predicting thermal conductivity of thin dielectric films: the equation of radiative transfer, the temperature‐dependent thermal conductivity theories based on the Callaway model, and the molecular dynamics simulation. This overview also highlights temporal and spatial scale issues by looking at a unified theory that bridges physical issues presented in the Fourier and Cattaneo models. This newly developed unified theory is the so‐called C‐ and F‐processes constitutive model. This model introduces the notion of a new dimensionless heat conduction model number, which is the ratio of the thermal conductivity of the fast heat carrier F‐processes to the total thermal conductivity comprised of both the fast heat carriers F‐processes and the slow heat carriers C‐processes. Illustrative numerical examples for prediction of thermal conductivity in thin films are primarily presented.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 14 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 6 August 2019

Ashwani Assam, Nikhil Kalkote, Nishanth Dongari and Vinayak Eswaran

Accurate prediction of temperature and heat is crucial for the design of various nano/micro devices in engineering. Recently, investigation has been carried out for calculating…

Abstract

Purpose

Accurate prediction of temperature and heat is crucial for the design of various nano/micro devices in engineering. Recently, investigation has been carried out for calculating the heat flux of gas flow using the concept of sliding friction because of the slip velocity at the surface. The purpose of this study is to exetend the concept of sliding friction for various types of nano/micro flows.

Design/methodology/approach

A new type of Smoluchowski temperature jump considering the viscous heat generation (sliding friction) has recently been proposed (Le and Vu, 2016b) as an alternative jump condition for the prediction of the surface gas temperature at solid interfaces for high-speed non-equilibrium gas flows. This paper investigated the proposed jump condition for the nano/microflows which has not been done earlier using four cases: 90° bend microchannel pressure-driven flow, nanochannel backward facing step with a pressure-driven flow, nanoscale flat plate and NACA 0012 micro-airfoil. The results are compared with the available direct simulation Monte Carlo results. Also, this paper has demonstrated low-speed preconditioned density-based algorithm for the rarefied gas flows. The algorithm captured even very low Mach numbers of 2.12 × 10−5.

Findings

Based on this study, this paper concludes that the effect of inclusion of sliding friction in improving the thermodynamic prediction is case-dependent. It is shown that its performance depends not only on the slip velocity at the surface but also on the mean free path of the gas molecule and the shear stress at the surface. A pressure jump condition was used along with the new temperature jump condition and it has been found to often improve the prediction of surface flow properties significantly.

Originality/value

This paper extends the concept of using sliding friction at the wall for micro/nano flows. The pressure jump condition was used which has been generally ignored by researchers and has been found to often improve the prediction of surface flow properties. Different flow properties have been studied at the wall apart from only temperature and heat flux, which was not done earlier.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 January 1990

Arturo O. Cifuentes, Timothy L. Bock and Robert N. Coppolino

This paper presents a finite element method for the study of gas‐lubricated bearings. The fluid is assumed to be compressible, and the effect of the molecular mean free path has…

Abstract

This paper presents a finite element method for the study of gas‐lubricated bearings. The fluid is assumed to be compressible, and the effect of the molecular mean free path has been incorporated into the formulation. A variational statement for the governing equation is derived and used to formulate a non‐linear quadrilateral finite element that has been incorporated into a standard code (MSC/NASTRAN). This constitutes a useful analysis tool for designers, especially in cases of complex bearing geometry. The results obtained with this method agree well with analytical solutions obtained by other authors for simple geometric configurations.

Details

Engineering Computations, vol. 7 no. 1
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 11 November 2013

Andrea G. Chiariello, Carlo Forestiere, Giovanni Miano and Antonio Maffucci

Nowadays, nano-antennas or nanoscale absorbers made by innovative materials such as carbon nanotubes are gaining more and more interest, because of their outstanding features. The…

1202

Abstract

Purpose

Nowadays, nano-antennas or nanoscale absorbers made by innovative materials such as carbon nanotubes are gaining more and more interest, because of their outstanding features. The purpose of this paper is to investigate the scattering properties of carbon nanotubes, either isolated or arranged in arrays. The peculiar behaviour of such innovative materials is studied, taking also into account the finite length of the structure and the dependence of the scattering field from the operating temperature.

Design/methodology/approach

First a model is presented for the electrical transport along the carbon nanotubes, based on Boltzmann quasi-classical transport theory. The model includes quantistic and inertial phenomena observed in the carbon nanotube electrodynamics. The model also includes the effects of temperature. Using this electrodynamical model, the electromagnetic formulation of the scattering problem is cast in terms of a Pocklington-like equation. The numerical solution is obtained by means of the Galerkin method, with special care in handling the logarithmic singularity of the kernel. Case studies are carried out, either referred to isolated single-wall carbon nanotubes (SWCNTs) and array of SWCNTs.

Findings

The scattering properties of SWCNT are strongly influenced by the temperature and by the distance between the tubes. As temperature increases, the amplitude of the resonance peaks decreases, at a rate which is double the rate of changes of temperature. The resonance frequencies are insensitive to temperature. As for the distance between the tubes in an array, it influence the scattering resonance introducing a shift in the resonance frequencies which is appreciable for distances lower than the semi-length of the CNT. For higher distances the CNT scattered field may be regarded as the sum of the fields emitted by each CNT, as if they were isolated.

Research limitations/implications

As far as now only SWCNTs have been studied. The multi-wall carbon nanotubes would show a richer behaviour with temperature, due to the joint effect of reduction of the mean free path and increase of the number of conducting channels, as temperature increases.

Practical implications

Possible use of carbon nanotubes as absorbing material or scatterers.

Originality/value

The model presented here is based on a self-consistent and physically meaningful description of the CNT electrodynamics, which takes rigorously into account the effect of temperature, size and chirality of each CNT.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 15 July 2021

Ramneek Sidhu and Mayank Kumar Rai

This paper aims to present the edge scattering dominant circuit modeling. The effect of crosstalk on gate oxide reliability (GOR), along with the mitigation using shielding…

Abstract

Purpose

This paper aims to present the edge scattering dominant circuit modeling. The effect of crosstalk on gate oxide reliability (GOR), along with the mitigation using shielding technique is further studied.

Design/methodology/approach

An equivalent distributed Resistance Inductance Capacitance circuit of capacitively coupled interconnects of multilayer graphene nanoribbon (MLGNR) has been considered for T Simulation Program with Integrated Circuit Emphasis (TSPICE) simulations under functional and dynamic switching conditions. Complementary metal oxide semiconductor driver transistors are modeled by high performance predictive technology model that drive the distributed segment with a capacitive load of 0.001 fF, VDD and clock frequency as 0.7 V and 0.2 GHz, respectively, at 14 nm technology node.

Findings

The results reveal that the crosstalk induced delay and noise area are dominated by the overall mean free path (MFP) (i.e. including the effect of edge roughness induced scattering), in contrary to, acoustic and optical scattering limited MFP with the temperature, width and length variations. Further, GOR, estimated in terms of average failure rate (AFR), shows that the shielding technique is an effective method to minimize the relative GOR failure rate by, 0.93e-7 and 0.7e-7, in comparison to the non-shielded case with variations in interconnect’s length and width, respectively.

Originality/value

Considering realistic circuit modeling for MLGNR interconnects by incorporating the edge roughness induced scattering mechanism, the outcomes exhibit more penalty in terms of crosstalk induced noise area and delay. The shielding technique is found to be an effective mitigating technique for minimizing AFR in coupled MLGNR interconnects.

Details

Circuit World, vol. 48 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 12 October 2010

Yograj Singh Duksh, Brajesh Kumar Kaushik, Sankar Sarkar and Raghuvir Singh

The purpose of this paper is to explore and evaluate the performance comparison of carbon nanotubes (CNT) and nickel silicide (NiSi) nanowires interconnects as prospective…

1405

Abstract

Purpose

The purpose of this paper is to explore and evaluate the performance comparison of carbon nanotubes (CNT) and nickel silicide (NiSi) nanowires interconnects as prospective alternatives to copper wire interconnects.

Design/methodology/approach

The increasing resistivity of the copper wire with scaling and rising demands on current density drives the need for identifying new wiring solutions. This paper explores the various alternatives to copper. The metallic bundle CNTs and NiSi nanowires are promising candidates that can potentially address the challenges faced by copper. This paper analyzes various electrical models of carbon nanotube and recently introduced novel interconnect solution using NiSi nanowires.

Findings

The theoretical studies proves CNTs and NiSi nanowires to be better alternatives against copper on the ground of performance parameters, such as effective current density, delay and power consumption. NiSi nanowire provides highest propagation speed for short wire length, and copper is the best for intermediate wire length, while bundle CNTs is faster for long wire length. NiSi nanowire has lowest power consumption than copper and CNTs.

Originality/value

This paper investigates, assess and compares the performance of carbon nanotubes (CNT) and NiSi nanowires interconnects as prospective alternatives to copper wire interconnects in future VLSI chips.

Details

Journal of Engineering, Design and Technology, vol. 8 no. 3
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 24 April 2007

Brajesh Kumar Kaushik, Saurabh Goel and Gaurav Rauthan

To review and explore optical fiber and carbon nanotube (CNT) as prospective alternatives to copper in VLSI interconnections.

1716

Abstract

Purpose

To review and explore optical fiber and carbon nanotube (CNT) as prospective alternatives to copper in VLSI interconnections.

Design/methodology/approach

As the technology moves to deep submicron level, the interconnect width also scales down. Increasing resistivity of copper with scaling and rising demands on current density drives the need for identifying new wiring solutions. This paper explores various alternatives to copper. Metallic CNTs, optical interconnects are promising candidates that can potentially address the challenges faced by copper.

Findings

Although, the theoretical aspects proves CNTs and optical interconnect to be better alternative against copper on the ground of performance parameters such as power dissipation, switching delay, crosstalk. But copper would last for coming decades on integration basis.

Originality/value

This paper reviews the state‐of‐the‐art in CNT interconnect and optical interconnect research; and discusses both the advantages and challenges of these emerging technologies.

Details

Microelectronics International, vol. 24 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 April 1948

In this informal symposium, presided over by R. D. Kelly, United Air Lines, after talks, rather than the reading of papers, the pilots concerned assembled on the rostrum and…

Abstract

In this informal symposium, presided over by R. D. Kelly, United Air Lines, after talks, rather than the reading of papers, the pilots concerned assembled on the rostrum and answered questions. They were:

Details

Aircraft Engineering and Aerospace Technology, vol. 20 no. 4
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 April 1960

A.D.Y. and B.W.M.

The term ‘hypersonic flow’ was first used by Tsien in 1946 to denote a (low for which the main stream Mach number was large compared with unity, and he demonstrated that such…

Abstract

The term ‘hypersonic flow’ was first used by Tsien in 1946 to denote a (low for which the main stream Mach number was large compared with unity, and he demonstrated that such flows displayed characteristic features which justified the use of a special name. Tsien confined his considerations to a perfect gas with constant specific heats but since 1946 interest has widened to the flow of real fluids at high Mach numbers, this interest being mainly stimulated by the problems of the re‐entry at high speeds into the earth's atmosphere of missiles and satellites. An essential feature of hypersonic flow is that relative to the undisturbed flow direction the inclination of the nose shock of a body immersed in the fluid is of the same order of magnitude as the mean inclination of the surface over the forward part of the body, and the region between shock and body, the so‐called ‘shock layer’, is relatively narrow there. Another characteristic feature is the high temperature that developes in this layer in problems of practical interest and the associated effects on the physical and chemical properties of the medium. Thus, not only must account be taken of the variation of the specific heats with temperature for a real fluid but the consequences of dissociation and ionization of the fluid on crossing the nose shock must be considered. The interaction of the boundary layer with the flow external to it and with the nose shock becomes of increasing importance, as well as increasingly complex, with increase of main stream Mach number. Finally, account must be taken of the molecular nature of the medium in problems where the density is sufficiently low for the mean free path of the molecules to be a significant ratio of a typical dimension of the body or of its boundary layer thickness.

Details

Aircraft Engineering and Aerospace Technology, vol. 32 no. 4
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 March 1985

P.R. Simon

The paper describes the physical phenomena which influence the electrical and mechanical characteristics of low temperature coefficient, high stability thin metal resistive films…

Abstract

The paper describes the physical phenomena which influence the electrical and mechanical characteristics of low temperature coefficient, high stability thin metal resistive films. Emphasis is placed on the Matthiensen and Arrhenius rules in respect of resistivity and time‐temperature stabilities. The phenomena outlined are highly dependent on the deposition methods used and film properties are discusssed in terms of the film formation kinetics, substrates, and deposition technologies. The production of thin metal film resistive films based on these principles readily achieves temperature coefficients of <5 ppm/°C over the temperature range −55°C to + 155°C with load stress stabilities of <300 ppm with full dissipation, 155°C, 2000 hours, which is as good as bulk nickel‐chromium alloy foil.

Details

Microelectronics International, vol. 2 no. 3
Type: Research Article
ISSN: 1356-5362

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