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Article
Publication date: 1 April 1959

Melvin Zaid and Frederick L. Ryder

A new analogue approach is presented for the solution to the multi‐celled, multi‐stringer tube subjected to flexural and torsional loads. This approach is based upon the condition…

18

Abstract

A new analogue approach is presented for the solution to the multi‐celled, multi‐stringer tube subjected to flexural and torsional loads. This approach is based upon the condition of current continuity and an equivalent to Castigliano's theorem which holds for certain types of electrical networks. The associated equations lend themselves to creating an analogue with a high degree of pictorial similarity, so that the network can be constructed without formulating the structural equations. The analogue of a simple two‐celled structure is devised and the results obtained by electrical circuit analysis are checked against the structure.

Details

Aircraft Engineering and Aerospace Technology, vol. 31 no. 4
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 14 May 2018

Ji Li, Thomas Wasley, Duong Ta, John Shephard, Jonathan Stringer, Patrick J. Smith, Emre Esenturk, Colm Connaughton, Russell Harris and Robert Kay

This paper aims to demonstrate the improved functionality of additive manufacturing technology provided by combining multiple processes for the fabrication of packaged electronics.

384

Abstract

Purpose

This paper aims to demonstrate the improved functionality of additive manufacturing technology provided by combining multiple processes for the fabrication of packaged electronics.

Design/methodology/approach

This research is focused on the improvement in resolution of conductor deposition methods through experimentation with build parameters. Material dispensing with two different low temperature curing isotropic conductive adhesive materials was characterised for their application in printing each of three different conductor designs, traces, z-axis connections and fine pitch flip chip interconnects. Once optimised, demonstrator size can be minimised within the limitations of the chosen processes and materials.

Findings

The proposed method of printing z-axis through layer connections was successful with pillars 2 mm in height and 550 µm in width produced. Dispensing characterisation also resulted in tracks 134 µm in width and 38 µm in height allowing surface mount assembly of 0603 components and thin-shrink small outline packaged integrated circuits. Small 149-µm flip chip interconnects deposited at a 457-µm pitch have also been used for packaging silicon bare die.

Originality/value

This paper presents an improved multifunctional additive manufacturing method to produce fully packaged multilayer electronic systems. It discusses the development of new 3D printed, through layer z-axis connections and the use of a single electrically conductive adhesive material to produce all conductors. This facilitates the surface mount assembly of components directly onto these conductors before stereolithography is used to fully package multiple layers of circuitry in a photopolymer.

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Article
Publication date: 1 September 1975

M.E. El Dahshan, J. Stringer and D.P. Whittle

1. Introduction The oxidation of cobalt‐chromium alloys has recently been reviewed in some detail by Wright. In the temperature range 950–1350°C (1740–2460°F), alloys containing…

93

Abstract

1. Introduction The oxidation of cobalt‐chromium alloys has recently been reviewed in some detail by Wright. In the temperature range 950–1350°C (1740–2460°F), alloys containing up to 15% Cr oxidize faster than pure cobalt, forming double‐layered scales: the outer layer is virtually pure CoO and the inner one is composed of Co‐Cr spinel particles in a chromium‐doped CoO matrix. For oxidation in air or in oxygen, if the specimens are heated in the gas, a sharp minimum in the rate is observed at about 25 %Cr, with the development of a continuous protective CT2O3 scale. However, if the alloys are rapidly exposed to oxygen at pressures above 100 Torr, then only a shallow minimum in rate is observed at about 25 to 30 %Cr, and the higher‐chromium alloys form a two‐layer scale similar to that found on the dilute alloys. Above 35 %Cr, the scale is always a thin single layer of Cr2O3.

Details

Anti-Corrosion Methods and Materials, vol. 22 no. 9
Type: Research Article
ISSN: 0003-5599

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Publication date: 8 August 2014

Karen Pierce, Ted D. Englebrecht and Wei-Chih Chiang

This study examines whether Revenue Procedure 2003-61 is an improvement over Revenue Procedure 2000-15, in the areas of taxpayers’ expectations for IRS equitable relief decisions…

Abstract

This study examines whether Revenue Procedure 2003-61 is an improvement over Revenue Procedure 2000-15, in the areas of taxpayers’ expectations for IRS equitable relief decisions and gender-related in-group bias. The survey instrument includes a vignette adapted from a judicial decision. The results show that Rev. Proc. 2003-61 does improve upon Rev. Proc. 2000-15. Furthermore, taxpayers perceive different expectations of what the IRS should do and what the IRS would do in equitable relief decision making. Also, gender-related in-group biases are found to be present for both genders. Tax policy implications regarding equitable relief are discussed.

Details

Advances in Accounting Behavioral Research
Type: Book
ISBN: 978-1-78190-838-9

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Article
Publication date: 8 February 2013

Masoud Fakhimi and Jane Probert

The purpose of this paper is to identify the existing literature on the wide range of operations research (OR) studies applied to healthcare, and to classify studies based on…

1895

Abstract

Purpose

The purpose of this paper is to identify the existing literature on the wide range of operations research (OR) studies applied to healthcare, and to classify studies based on application type and on the OR technique employed. The scope of the review is limited to studies which have been undertaken in the UK, and to papers published since the year 2000.

Design/methodology/approach

In total, 142 high‐quality journal and conference papers have been identified from ISI Web of Knowledge data base for review and analysis.

Findings

The findings categorise the OR techniques employed, and analyse the application type, publication trends, funding, and software packages used in the twenty‐first century in UK healthcare. Publication trends indicate an increasing use of OR techniques in UK healthcare. The findings show that, interestingly, the distribution of the OR techniques employed is not uniform; the majority of studies focus on simulation, either as the only technique employed or as one element of a multi‐method approach.

Originality/value

Several studies have focused on the use of simulation in healthcare modelling, but none has methodologically reviewed the use of the full range of OR techniques. This research is likely to benefit healthcare decision makers since it will provide them with an overview of the different studies that have utilised multiple OR techniques for investigating problems in the stated domain.

Details

Journal of Enterprise Information Management, vol. 26 no. 1/2
Type: Research Article
ISSN: 1741-0398

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Article
Publication date: 11 November 2022

Ruiliang Feng, Jingchao Jiang, Atul Thakur and Xiangzhi Wei

Two-level support with Level 1 consisting of a set of beams and Level 2 consisting of a tree-like structure is an efficient support structure for extrusion-based additive…

169

Abstract

Purpose

Two-level support with Level 1 consisting of a set of beams and Level 2 consisting of a tree-like structure is an efficient support structure for extrusion-based additive manufacturing (EBAM). However, the literature for finding a slim two-level support is rare. The purpose of this paper is to design a lightweight two-level support structure for EBAM.

Design/methodology/approach

To efficiently solve the problem, the lightweight design problem is split into two subproblems: finding a slim Level 1 support and a slim Level 2 support. To solve these two subproblems, this paper develops three efficient metaheuristic algorithms, i.e. genetic algorithm (GA), genetic programming (GP) and particle swarm optimization (PSO). They are problem-independent and are powerful in global search. For the first subproblem, considering the path direction is a critical factor influencing the layout of Level 1 support, this paper solves it by splitting the overhang region into a set of subregions, and determining the path direction (vertical or horizontal) in each subregion using GA. For the second subproblem, a hybrid of two metaheuristic algorithms is proposed: the GP manipulates the topologies of the tree support, while the PSO optimizes the position of nodes and the diameter of tree branches. In particular, each chromosome is encoded as a single virtual tree for GP to make it easy to manipulate Crossover and Mutation. Furthermore, a local strategy of geometric search is designed to help the hybrid algorithm reach a better result.

Findings

Simulation results show that the proposed method is preferred over the existing method: it saves the materials of the two-level support up to 26.34%, the materials of the Level 1 support up to 6.62% and the materials of the Level 2 support up to 37.93%. The proposed local strategy of geometric search can further improve the hybrid algorithm, saving up to 17.88% of Level 2 support materials.

Research limitations/implications

The proposed approach for sliming Level 1 support requires the overhanging region to be a rectilinear polygon and the path direction in a subregion to be vertical or horizontal. This limitation limits the further material savings of the Level 1 support. In future research, the proposed approach can be extended to handle an arbitrary overhang region, each with several choices of path directions.

Practical implications

The details of how to integrate the proposed algorithm into the open-source program CuraEngine 4.13.0 is presented. This is helpful for the designers and manufacturers to practice on their own 3D printers.

Originality/value

The path planning of the overhang is a critical factor influencing the distribution of supporting points and will thus influence the shape of the support structure. Different from existing approaches that use single path directions, the proposed method optimizes the volume of the support structure by planning hybrid paths of the overhangs.

Details

Rapid Prototyping Journal, vol. 29 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 March 1957

W.J. Goodey

IN this part we shall consider the effect of non‐uniformity (with respect to k) in the longitudinal members, with particular reference to the case of four longerons, and we shall…

26

Abstract

IN this part we shall consider the effect of non‐uniformity (with respect to k) in the longitudinal members, with particular reference to the case of four longerons, and we shall then go on to discuss the treatment of cut‐outs.

Details

Aircraft Engineering and Aerospace Technology, vol. 29 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 January 1957

W.J. Goodey

METHOD for the stress analysis of the circular conical fuselage with flexible frames, subjected to a fairly general type of load distribution, was recently developed by the…

35

Abstract

METHOD for the stress analysis of the circular conical fuselage with flexible frames, subjected to a fairly general type of load distribution, was recently developed by the present writer in a paper published in the Journal of the Royal Aeronautical Society. This paper did not, however, make any attempt to deal with the question of cut‐outs, and for the reason given below it later transpired that certain modifications of the basic theory were required before this problem could be solved.

Details

Aircraft Engineering and Aerospace Technology, vol. 29 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 9 September 2014

Gang Liu, Wei Tang, Ying-Lin Ke, Qing-Liang Chen and Yunbo Bi

The purpose of this paper is to propose a new model for optimizing pre-joining processes quickly and accurately, guiding workers to standardized operations. For the automatic…

302

Abstract

Purpose

The purpose of this paper is to propose a new model for optimizing pre-joining processes quickly and accurately, guiding workers to standardized operations. For the automatic riveting in panel assemblies, the traditional approach of determination of pre-joining processes entirely rests on the experience of workers, which leads to the improper number, location and sequence of pre-joining, the low quality stability and the high repair rate in most cases.

Design/methodology/approach

The clearances computation with the complete finite element model for every process combination is time-consuming. Therefore a fast pre-joining processes optimization model (FPPOM) is proposed. This model treats both the measured initial clearances and the stiffness matrices of key points of panels as an input; considers the permissive clearances as an evaluation criterion; regards the optimal number, location and sequence as an objective; and takes the neighborhood-search-based adaptive genetic algorithm as a solution.

Findings

A comparison between the FPPOM and complete finite element model with clearances (CFEMC) was made in practice. Further, the results indicate that running the FPPOM is time-saving by >90 per cent compared with the CFEMC.

Practical implications

This paper provides practical insights into realizing the pre-joining processes optimization quickly.

Originality/value

This paper is the first to propose the FPPOM, which could simplify the processes, reduce the degrees of freedom of nodes and conduct the manufacturers to standardized manipulations.

Details

Assembly Automation, vol. 34 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 28 February 2023

Haiyang Hu, Yu Wang, Chenchen Lian and Peiyan Wang

In this paper, an attempt is made to obtain buckling loads, ultimate bearing capacity and other required structural characteristics of grid structure panels. The numerical method…

138

Abstract

Purpose

In this paper, an attempt is made to obtain buckling loads, ultimate bearing capacity and other required structural characteristics of grid structure panels. The numerical method for post-buckling behavior analysis of panels involving multiple invisible damages is also presented.

Design/methodology/approach

In this paper, two bidirectional stiffened composite panels are manufactured and tested. Multiple discrete invisible damages are introduced in different positions of the stringers, and the experimental and simulation investigation of buckling and post-buckling were carried out on the damaged stiffened panels.

Findings

The simulation load–displacement curves are compared with the experimental results, and it is found that the simulation model can well predict the occurrence of buckling and failure loads. The strain curve shows that the rate of strain change at the damaged site is greater than that at the undamaged site, which reflects that the debond is more likely occurred at the damaged site. The simulation verifies that the panel is usually crushed due to matrix compression and fiber–matrix shear.

Originality/value

In this paper, post-buckling tests and numerical simulations of bidirectional stiffened composite panels with impact damage were carried out. Two panels with four longitudinal stringers and two transverse stringers were manufactured and tested. The buckling and post-buckling characteristics of the grid structure are obtained, and the failure mechanism of the structure is explained. This is helpful for the design of wall panel structure.

Details

Multidiscipline Modeling in Materials and Structures, vol. 19 no. 3
Type: Research Article
ISSN: 1573-6105

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