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Article
Publication date: 7 June 2013

John S. Usher, Timothy J. Gornet and Thomas L. Starr

This paper seeks to present the results of an experiment to investigate the effect of six part orientation (XY, XZ, YX, YZ, ZY, ZX) and a wide range of energy densities on…

Abstract

Purpose

This paper seeks to present the results of an experiment to investigate the effect of six part orientation (XY, XZ, YX, YZ, ZY, ZX) and a wide range of energy densities on ultimate tensile strength (UTS) and elongation of laser‐sintered nylon 12 (PA‐12) test specimens.

Design/methodology/approach

ASTM Type 1 specimens were built on a DTM Sinterstation 2500+ and tensile tested on an Instron 5569 A. The resulting data were fit to non‐linear regression models based on the well‐known Weibull growth model to predict each response based on the total energy density used in each trial.

Findings

The resulting regression models provide excellent fits with low sum of squared errors and normally distributed residuals. The resulting material properties are highly affected by the energy density and the build orientation. However, once sufficient energy density is applied, properties tend to converge to consistent values. To achieve maximum UTS of approximately 52 MPa, it is recommended that values of energy density above 0.25 W‐s per mm3 be used. To achieve maximum elongation of approximately 15‐16 percent, it is recommended that values of energy density above 0.40 W‐s per mm3 be used when building parts in the XY, XZ, YX, YZ orientations. Parts built in the ZX orientation exhibit lower elongation values at or below 12 percent for even high values of energy density.

Originality/value

This paper extends previous work of Starr, Gornet and Usher on the relationship between material properties, part orientation and energy density by proposing the use of the Weibull growth model. Recommendations are provided to assist users in the selection of correct energy density to achieve desirable mechanical properties in each specified orientation.

Details

Rapid Prototyping Journal, vol. 19 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 5 April 2011

Y. Arayici, P. Coates, L. Koskela, M. Kagioglou, C. Usher and K. O'Reilly

This paper aims to present a systematic approach for building information modelling (BIM) implementation for architectural SMEs at the organizational level

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12651

Abstract

Purpose

This paper aims to present a systematic approach for building information modelling (BIM) implementation for architectural SMEs at the organizational level

Design/methodology/approach

The research is undertaken through a knowledge transfer partnership (KTP) project between the University of Salford and John McCall Architects (JMA) a SME based in Liverpool. The overall aim of the KTP is to develop lean design practice through BIM adoption. The BIM implementation approach uses a socio‐technical view, which does not only consider the implementation of technology but also considers the socio‐cultural environment that provides the context for its implementation. The action research oriented qualitative and quantitative research is used for discovery, comparison, and experimentation as it provides “learning by doing”.

Findings

The strategic approach to BIM adoption incorporated people, process and technology equally and led to capacity building through the improvements in process, technological infrastructure and upskilling of JMA staff to attain efficiency gains and competitive advantages.

Originality/value

The paper introduces a systematic approach for BIM adoption based on the action research philosophy and demonstrates a roadmap for BIM adoption at the operational level for SME companies.

Details

Structural Survey, vol. 29 no. 1
Type: Research Article
ISSN: 0263-080X

Keywords

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Article
Publication date: 1 May 2002

Jonathon T. Fite, G. Don Taylor, John S. Usher, John R. English and John N. Roberts

This paper describes the results of an effort to predict future freight volume in the truckload (TL) trucking industry. The approach involves the use of stepwise multiple…

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2693

Abstract

This paper describes the results of an effort to predict future freight volume in the truckload (TL) trucking industry. The approach involves the use of stepwise multiple linear regression models that relate freight volume to a variety of economic indicators. The models are built using a large set of actual freight data provided by J.B. Hunt Transport (JBHT), one of the world’s largest TL carriers. The data was first analyzed using the overall set of national data, and then for specific industrial and regional segments. The overall results of these analyses should prove useful to a wide variety of transportation and logistics operations.

Details

International Journal of Physical Distribution & Logistics Management, vol. 32 no. 4
Type: Research Article
ISSN: 0960-0035

Keywords

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Article
Publication date: 19 June 2007

Anthony S. Humphrey, G. Don Taylor, John S. Usher and Gary L. Whicker

The purpose of this paper is to examine whether or not driver life, carrier performance, and customer service can be improved as a result of the use of a technique called…

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1370

Abstract

Purpose

The purpose of this paper is to examine whether or not driver life, carrier performance, and customer service can be improved as a result of the use of a technique called yard‐stacking in the truckload trucking industry. The technique seeks to find ways to provide level freight availability during normal weekly cycles in an effort to seek improvement relative to all constituencies.

Design/methodology/approach

Simulation is used to examine the use of yard‐stacking on Fridays to provide additional freight on weekends, which is generally much less available than on weekdays. In this technique, before being dispatched on Friday for a long‐haul, a driver initially picks up a load to make a short “dray” move from the customer site to the carrier's closest terminal yard. During the weekend, another driver picks up the drayed load. In this research, we evaluate the potential of weekend yard‐stacking under a variety of scenarios.

Findings

The paper shows that a carrier's adaptation of weekend freight leveling can be beneficial to both trucking companies and their customers, while remaining relatively neutral to drivers.

Research limitations/implications

Carriers may be able to utilize Friday yard‐stacking to improve their cost efficiency, driver satisfaction and customer performance.

Originality/value

This research extends the knowledge base of truckload freight imbalance problems. It was industrially motivated by J.B. Hunt Transport, Inc., one of the world's largest truckload carriers, who provided freight data and conceptual guidance.

Details

International Journal of Physical Distribution & Logistics Management, vol. 37 no. 5
Type: Research Article
ISSN: 0960-0035

Keywords

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Article
Publication date: 17 August 2010

Kamran S. Moghaddam and John S. Usher

This paper seeks to develop and present a new mathematical formulation to determine the optimal preventive maintenance and replacement schedule of a system.

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1652

Abstract

Purpose

This paper seeks to develop and present a new mathematical formulation to determine the optimal preventive maintenance and replacement schedule of a system.

Design/methodology/approach

The paper divides the maintenance‐planning horizon into discrete and equally‐sized intervals and in each period decide on one of three possible actions: maintain the system, replace the system, or do nothing. Each decision carries a specific cost and affects the failure pattern of the system. The paper models the cases of minimizing total cost subject to a constraint on system reliability, and maximizing the system reliability subject to a budgetary constraint on total cost. The paper presents a new mathematical function to model an improvement factor based on the ratio of maintenance and repair costs, and show how it outperforms fixed improvement factor models by analyzing the effectiveness in terms of cost and reliability of the system.

Findings

Optimal decisions in each period over a planning horizon are sought such that the objectives and the requirements of the system can be achieved.

Practical implications

The developed mathematical models for this improvement factor can be used in theoretical and practical situations.

Originality/value

The presented models are effective decision tools that find the optimal solution of the preventive maintenance and replacement scheduling problem.

Details

Journal of Quality in Maintenance Engineering, vol. 16 no. 3
Type: Research Article
ISSN: 1355-2511

Keywords

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Article
Publication date: 4 October 2011

Thomas L. Starr, Timothy J. Gornet and John S. Usher

The purpose of this paper is to measure the effect of process conditions on mechanical properties of laser‐sintered nylon 12 (Duraform®) and to determine the range of…

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1998

Abstract

Purpose

The purpose of this paper is to measure the effect of process conditions on mechanical properties of laser‐sintered nylon 12 (Duraform®) and to determine the range of conditions that provide consistent mechanical performance for additive manufacturing.

Design/methodology/approach

Tensile test specimens were fabricated over a range of well‐characterized process conditions including laser power, laser speed, scan spacing, layer thickness, build orientation, and build position. Tensile modulus, yield strength, ultimate tensile strength and elongation‐at‐fracture were measured and related to process parameters.

Findings

Tensile properties are strongly related to the amount of energy deposited during scanning. Strength and modulus approach their maximum values as the energy deposited exceeds the amount needed to fully melt the applied powder. Elongation‐at‐fracture does not reach its maximum until higher energy‐melt ratio. Performance of blends with reused powder matches that of virgin powder when blend composition is adjusted to a standard melt‐flow index. The volumetric energy density and the energy‐melt ratio are useful for correlating mechanical properties with multiple process parameters and material thermal properties.

Originality/value

This work presents the most extensive data to date on mechanical properties of nylon 12 (Duraform®) as they relate to the full range of process parameters. These data show that mechanical performance correlates strongly with the volume energy density. In contrast to the area energy density (a.k.a. Andrews Number), this volumetric parameter includes the effect of varying layer thickness and can be related directly to the melting characteristics of the polymer material. Within the parameter range studied, this relationship allows adjustment of one scan parameter for improved speed or dimensional accuracy while ensuring good strength by an offsetting adjustment of another parameter. Such trade‐offs will be important in future manufacturing applications of the laser sintering process. Understanding the energy‐melt ratio provides insight into the relationship between scan conditions and the physics of powder melting and sintering, and offers a methodology to relate results at other bed temperatures and with other polymer powders.

Details

Rapid Prototyping Journal, vol. 17 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Abstract

Details

Documents on and from the History of Economic Thought and Methodology
Type: Book
ISBN: 978-1-84663-909-8

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Article
Publication date: 1 January 1976

Alfred Hodina and Arthur Anthony

1. Eshbach, Ovid W. and Mott Souders (eds.). Handbook of Engineering Fundamentals, 3rd edition. New York, John Wiley and Sons, 1975. 1562p. $24.95. Engineering handbooks…

Abstract

1. Eshbach, Ovid W. and Mott Souders (eds.). Handbook of Engineering Fundamentals, 3rd edition. New York, John Wiley and Sons, 1975. 1562p. $24.95. Engineering handbooks are notorious for the excessively long periods of time it takes for them to come out as revised editions. Periods of anywhere from ten to twenty years can be expected for a revision process and which, unfortunately, appears to be more of the rule than the exception. This 3rd edition of the Handbook of Engineering Fundamentals is welcome for it has been more than twenty years since the publication of the 2nd edition, and has been very much overdue for revision.

Details

Reference Services Review, vol. 4 no. 1
Type: Research Article
ISSN: 0090-7324

Content available
Book part
Publication date: 11 November 2019

Deb Aikat

Dubbed as the “first digital generation,” the millennials (or Generation Y) have been ensconced in digital technologies throughout their lives. As a demographic cohort…

Abstract

Dubbed as the “first digital generation,” the millennials (or Generation Y) have been ensconced in digital technologies throughout their lives. As a demographic cohort, the eldest members of Generation Y were the first to reach adulthood by 2001, which heralded the third millennium, and were, therefore, called the millennials.

This research study theorizes that the millennials are ushering an emerging post-digital era that is redefining how we live, work, and play. By situating media consumption within a cross-disciplinary context of mediated engagement, this study analyzed how millennials consume media based on a 2019 meta-analytical research analysis of 22 cross-disciplinary studies, published between 2015 and 2019.

This research study analyzes how millennials curate and engage with digital media and information content in the midst of incessant evolutions of their identity, media use, and digital life. This study explicates six theoretical insights into how millennials consume information and engage with media. In their pursuit of easy access to media, the millennials get most of their information and media content from social media.

In theorizing how millennials engage with digital media, this study explicates important conceptual trends such as incidental news exposure (INE), which refers to people stumbling upon news stories they otherwise would not have purposefully seen or sought. INE spawns “bumpers” who involuntarily bump into news items, as opposed to “seekers” who actively search or seek news content. This leads to the news-finds-me mindset among some passive news consumers who rely and expect other active news consumers to share important news and information.

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Article
Publication date: 1 March 2001

K.G.B. Bakewell

Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐18; Journal of Property Investment & Finance Volumes…

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15651

Abstract

Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐18; Journal of Property Investment & Finance Volumes 8‐18; Property Management Volumes 8‐18; Structural Survey Volumes 8‐18.

Details

Structural Survey, vol. 19 no. 3
Type: Research Article
ISSN: 0263-080X

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