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Article
Publication date: 2 January 2007

O.S. Aleksić, B.M. Radojčić and R.M. Ramović

The paper aims to focus on thick film planar thermistors.

Abstract

Purpose

The paper aims to focus on thick film planar thermistors.

Design/methodology/approach

Thick film planar thermistors such as rectangular, sandwich, multilayer, segmented and interdigitated were printed of law temperature NTC paste called NTC 3K3 95/2 (Ei Iritel). Their resistivity was measured at room temperature as a function of volume resistivity variations due to electrode effect (diffusion of PdAg into NTC layer) and variation of geometrical parameters such as length l, width w, thickness d, number of segments n. The experimental data obtained were used in forming a model by the simple fitting procedure for counting diffusion effect on volume resistivity and resistivity dependence on geometrical parameters.

Findings

Thermal behavior of NTC thick films was measured in the range of −30‐120°C. Exponential factor B was fitted for measured values and included in the proposed thick film thermistors model. The agreement of measured and calculated data enables simulation of new thermistor geometries.

Originality/value

The paper focuses on the experiment which was the first step in forming a total physical/mathematical model proposed for thick film thermistor resistivity.

Details

Microelectronics International, vol. 24 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 January 1986

On October 31st 1985, 48 members of the ISHM‐Benelux Chapter met at the Delft University of Technology for the Autumn 1985 meeting.

Abstract

On October 31st 1985, 48 members of the ISHM‐Benelux Chapter met at the Delft University of Technology for the Autumn 1985 meeting.

Details

Microelectronics International, vol. 3 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 10 August 2015

Luciano Castro Lara, Henara Costa and José Daniel Biasoli de Mello

This paper aims to analyse the influence of the thickness of different layers [diamond-like-carbon (DLC) and chromium nitride (CrN)] on the sliding wear behaviour of a…

Abstract

Purpose

This paper aims to analyse the influence of the thickness of different layers [diamond-like-carbon (DLC) and chromium nitride (CrN)] on the sliding wear behaviour of a multifunctional coating on AISI 1020 substrates. When small and cheap components need to be manufactured in large scale, they are often produced using soft metals, such as unhardened low carbon steels and pure iron.

Design/methodology/approach

Two families, one with thicker films and the other with thinner films, were deposited onto a soft carbon steel substrate by plasma-enhanced chemical vapour deposition (PECVD). Reciprocating linear tests with incremental loading assessed the durability of the coatings. In addition, friction coefficient and wear rates of both specimens and counterbodies were measured at a constant load.

Findings

Thinner layers presented lower sliding wear rates (four-five times lower) for both specimens and counterbodies, less spalling and protective tribolayers on the wear tracks.

Originality/value

Although multilayered CrN–DLC coatings on relatively hard substrates such as HSS and cemented carbide tools are already a proven technology, much less is known about its deposition on a much softer substrate such as low carbon steel. In previous works, we have analysed the influence of layer thickness on hardness and scratch resistance of the same coatings. This paper presents results for their performance under wear sliding conditions using an original approach (three-dimensional triboscopic maps) for two distinct configurations (increasing load and constant load).

Details

Industrial Lubrication and Tribology, vol. 67 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 10 May 2011

R.N. Jadhav and Vijaya Puri

The purpose of this paper is to describe the use of copper‐substituted nickel manganite thick film and bulk ceramic superstrate on Ag thick film microstrip straight…

Abstract

Purpose

The purpose of this paper is to describe the use of copper‐substituted nickel manganite thick film and bulk ceramic superstrate on Ag thick film microstrip straight resonator (MSR), to modify its response and measure complex permittivity as a function of copper.

Design/methodology/approach

The glass frit free (fritless) copper‐substituted nickel manganite thick films were formulated on alumina substrate by screen printing technique from the powder synthesized by oxalic precursor method. A comparison has been made between the X band response of Ag thick film MSR due to perturbation of bulk and thick film Ni(1−x)CuxMn2O4 (0≤x≤1) ceramic. The shift has been used to measure the permittivity of the ceramic. The dielectric constants obtained by superstrate technique on Ag thick film microstrip component are comparable to those obtained from theoretical calculations.

Findings

The resonance frequency of MSR shifts towards lower frequency due to the presence of Ni(1−x)CuxMn2O4 (0≤x≤1) ceramic as superstrate. The dielectric constant of bulk and thick film match well with the theoretical values. The dielectric constant increases with copper concentration and shows reduction of power gain of MSR. The peak output (power gain) of MSR due to thick film NiMn2O4 increases by 10.19 per cent with decrease in bandwidth and increase in the quality factor with copper concentration.

Originality/value

The superstrate on Ag thick film straight resonator is an efficient tool capable of detecting the composition‐dependent changes in microwave properties of ceramic thick films. These Ni(1−x)CuxMn2O4 ceramic being thermistor materials apart from modifying the response can also be used as power sensors providing cost‐effective miniaturization.

Details

Microelectronics International, vol. 28 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 1 May 1994

A. Nag, A. Sarkar and V.M.K. Sastri

The effect of a horizontal partial porous partition on heat transfer andflow structure in a differentially heated square cavity is investigated.While the fluid flow is…

Abstract

The effect of a horizontal partial porous partition on heat transfer and flow structure in a differentially heated square cavity is investigated. While the fluid flow is assumed to be governed by Navier—Stokes equations, fluid saturated porous media is assumed to be governed by Darcy’s equations. Standard Galerkin method of finite element formulation is applied for discretization of the system of equations. The non‐linearities in the discretized equations are treated with Newton‐Raphson scheme. The code developed is tested for validation for modified Rayleigh number Ra up to 400. The code is then applied to a differentially heated square cavity with a horizontal partial porous partition. While the thickness of the porous partition is found to have appreciable effect on heat transfer and flow field, width of the porous partition is found to have insignificant bearing on heat transfer except when the partition is very small and compatible to the thickness of the boundary layer developed. During the experimentation Darcy number and Rayleigh number are assumed to be constant at 10–4 and 106 respectively.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 4 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 25 January 2013

Roberto Poli

The purpose of this paper is to explain why finding a theory for futures studies is such a demanding task. In particular, the paper paves the way towards a theoretical

Abstract

Purpose

The purpose of this paper is to explain why finding a theory for futures studies is such a demanding task. In particular, the paper paves the way towards a theoretical framework that goes beyond both positivism and anti‐positivism.

Design/methodology/approach

The paper discusses a network of mutually interlinked concepts, including: levels of reality; parts and wholes; causation; the multiplicity of times; anticipation; the thick present; and latents.

Findings

The paper presents the two main obstructions blocking the way towards a theory for futures studies (namely, the belief that the opposition between positivists and anti‐positivists is exhaustive, and the need for better connections with other sciences such as biology, cognitive science and the social sciences.

Research limitations/implications

The paper discusses only one of the different threads in the elaboration of a theoretical basis for futures studies, namely the components closer to science.

Social implications

A proper theory for futures studies will contribute to making them more robust and efficient.

Originality/value

The general framework presented by the paper extends well beyond the somewhat restricted field of futures studies and includes social and psychological sciences, together with biology.

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Article
Publication date: 18 January 2016

Mengqi Yuan and David Bourell

The purpose of this paper is to improve the quality of additive manufactured optically translucent parts by investigating the manufacturing issues, analyzing lithophane…

Abstract

Purpose

The purpose of this paper is to improve the quality of additive manufactured optically translucent parts by investigating the manufacturing issues, analyzing lithophane production criteria and identifying the best translucent material and additive manufacturing (AM) technology.

Design/methodology/approach

Figured lithophanes were laser sintered on a 3D Systems SinterStation® HiQ™ with varying layer thickness and plate thickness. Laser sintered (LS) polyamide (PA) 12 blanks were cyanoacrylate infiltrated and polished. Optical properties and performance were compared with the original LS blanks. Lithophanes and blanks were manufactured using 3D systems stereo lithography apparatus (SLA)® Viper ™si2 station, and optical properties and lithophane performance were compared with the LS specimens.

Findings

When building in the XY plane, it is optimal to sinter with the minimum layer thickness (0.076 mm) and maximum plate thickness (5 mm). Cyanoacrylate infiltration and polishing assists in reducing the LS PA 12 plate surface roughness, but polishing does not affect the lithophane performance. The best LS candidate should have an absorption coefficient of 0.5/mm using a white light source. Improved resolution but reduced contrast was observed on stereolithography (SL) specimens compared to LS parts.

Research limitations/implications

Transmittance experiments were performed on three SL parts which was not sufficient for optical property calculation. Limited literature was found for new material exploration.

Originality/value

It is the first effort to study systematically quality improvement issues of LS PA optically translucent parts. A comparison is made of optical performance between parts made using LS and SL.

Details

Rapid Prototyping Journal, vol. 22 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 25 January 2013

Anthony Hodgson

The purpose of this paper is to propose that conceptions of time and future that are currently in use restrict the possibilities for framing decision making. By

Abstract

Purpose

The purpose of this paper is to propose that conceptions of time and future that are currently in use restrict the possibilities for framing decision making. By privileging the notion of present moment over that of linear time, a more comprehensive framing of what it means to consider what influences our judgements. The ontology of the present moment provides a theoretical context for knowing what we can of the future in a more comprehensive way.

Design/methodology/approach

A review of ways of knowing the future that extends beyond linear assumptions of time leads to consideration of anticipatory systems and of the relationship between purpose and causality. It leads further into conjecture that the present moment is more ontologically fundamental than what we customarily refer to as past, present and future.

Findings

On this foundation, examination of experience of now reveals a multidimensionality which can include retrocausality, the possibility of the future influencing the present and the importance of latent patterning in determining events.

Research limitations/implications

The notion of the present moment has much in common with second order cybernetics and indicates a possible way of bringing systems thinking, especially boundary critique, to futures thinking and strategic decision making.

Practical implications

Although basically a theoretical paper, the framework does suggest possibilities for redesigning futures practice through using the present moment as a meta‐framing critique technique to reveal more clearly underlying assumptions in both futures studies and systems thinking.

Originality/value

In the context of a world where serious inability to see what is coming is pervasive in management and governance, a fresh look at fundamental assumptions may reveal flawed decision thinking and indicate ways of improvement.

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Article
Publication date: 12 April 2018

Aref Mehditabar, Gholam H. Rahimi and Seyed Ebrahim Vahdat

The purpose of this paper is to investigate the characterizations of high energy thick-walled functionally graded (FG) cylinder containing Al-26%Cu fabricated by…

Abstract

Purpose

The purpose of this paper is to investigate the characterizations of high energy thick-walled functionally graded (FG) cylinder containing Al-26%Cu fabricated by horizontal centrifugal casting technique.

Design/methodology/approach

Field emission scanning electron microscopy in conjunction with image analyser software and energy dispersion spectroscopy is applied to measure the variations of constituent phase’s content and elemental ratios along the radial direction, respectively. Distributions of the FG properties are measured through hardness, CTE, E and σy along the radial direction to investigate the mechanical and physical properties corresponding to the variations in microstructure. In addition, the variations of wear rate along the thickness are evaluated through a series of dry sliding wear tests using the pin-on-disk wear machine. Moreover, scanning electron microscopy is employed to characterize the worn-out surfaces and morphology of wear debris in order to clarify the dominant operative wear mechanism.

Findings

Results showed that Al2Cu content gradually decreases from the inner wall containing 33.3 vol.% to outer wall containing 26.4 vol.% in the FG cylindrical shell. The elastic modulus and yield strength measured through compression tests reveal that these mechanical properties are limited up to certain value of Al2Cu. The obtained optimum value of Al2Cu content for studied Al-Al2Cu FG is almost 31 vol.%.

Originality/value

The obtained optimum value of Al2Cu content for studied Al-Al2Cu FG was almost 31 vol.%.

Details

Multidiscipline Modeling in Materials and Structures, vol. 14 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

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Article
Publication date: 1 April 2005

Vijaya Puri, S.M. Salunkhe and M.M. Puranik

Use of thin film microstrip patch antenna for leaf moisture studies.

Abstract

Purpose

Use of thin film microstrip patch antenna for leaf moisture studies.

Design/methodology/approach

In this paper, the studies on the effect of leaf used as in‐touch overlay on thin film microstrip patch antenna in the X band (8‐12 GHz) is reported. The patch was used as the transmitting antenna and a pyramidal horn antenna was the receiving antenna. Three leaves Furcarea Gigantea, Kalanchoe Pinnata and Cereus Prerogonus have been used as overlay. All these leaves have high chlorophyll content, but are different in their surface texture and rate of moisture loss.

Findings

Size of leaf, orientation with respect to direction of propagation and moisture content dependent changes in the patch antenna output are observed. When the size of the overlay is larger than the patch and the feedline is in contact with it, frequency changes are more, whereas when only patch is in contact with the leaf, amplitude changes are more. Thin film microstrip antenna can provide a means for sensing moisture content in leafy vegetation.

Originality/value

The study of moisture effects of leafy vegetation using the technique of in‐touch overlay on microstrip components can be used to generate data base about the plant conditions in various places.

Details

Microelectronics International, vol. 22 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

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