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Article
Publication date: 1 September 1996

Neal K. Vail, Badrinarayan Balasubramanian, Joel W. Barlow and Harris L. Marcus

Reports that measurable amounts of polymer degradation occur during the fabrication of objects from polymer coated ceramic powders by selective laser sintering (SLS)…

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Reports that measurable amounts of polymer degradation occur during the fabrication of objects from polymer coated ceramic powders by selective laser sintering (SLS). Argues that because the binder is important in achieving strong green parts that can be handled with minimal breakage during post‐processing operations, it is essential to minimize the extent of binder losses. As the first step towards understanding the mechanisms of binder degradation, this paper presents a thermal model of the physical system, noting that the agreement between theory and experiment are good. The model is used to help determine the most influential parameters affecting binder losses during fabrication from polymer coated powders. Predicts that adjustments to laser beam diameter, laser scanning distance and gaseous environment will strongly affect polymer binder degradation during processing. Further predicts correctly that polymer degradation during SLS processing is not sensitive to the inherent degradation kinetics of the polymer.

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Rapid Prototyping Journal, vol. 2 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 September 1996

Joel W. Barlow, Joseph J. Beaman and Badrinarayan Balasubramanian

Presents the mechanical properties of a new mould‐making material, proposed for producing rapidly prototyped injection mould inserts for plastics by selective laser…

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Abstract

Presents the mechanical properties of a new mould‐making material, proposed for producing rapidly prototyped injection mould inserts for plastics by selective laser sintering. Explains that although the strength of this material is far below that of the tool steel usually used to fabricate moulds, design calculations indicate that it can still be used for mould insert production. Points out that the thermal conductivity of this material is lower than that for steel but higher than that for plastic melts. Indicates from the calculations that proper choices of conduction length and cycle time can minimize differences, relative to steel moulds, in the operational behaviour of moulds made of the new material. Discusses the longevity of example moulds.

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Rapid Prototyping Journal, vol. 2 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 April 2003

Georgios I. Zekos

Aim of the present monograph is the economic analysis of the role of MNEs regarding globalisation and digital economy and in parallel there is a reference and examination…

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Aim of the present monograph is the economic analysis of the role of MNEs regarding globalisation and digital economy and in parallel there is a reference and examination of some legal aspects concerning MNEs, cyberspace and e‐commerce as the means of expression of the digital economy. The whole effort of the author is focused on the examination of various aspects of MNEs and their impact upon globalisation and vice versa and how and if we are moving towards a global digital economy.

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Managerial Law, vol. 45 no. 1/2
Type: Research Article
ISSN: 0309-0558

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Article
Publication date: 1 June 1995

Kamatchi Subramanian, Neal Vail, Joel Barlow and Harris Marcus

The selective laser sintering (SLS) process is used to prepare test bars from Al2O3/polymer binder powders. Finds that binder‐coated A12O3 particles formed bars that were…

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Abstract

The selective laser sintering (SLS) process is used to prepare test bars from Al2O3/polymer binder powders. Finds that binder‐coated A12O3 particles formed bars that were approximately twice as strong as could be formed from mixtures of alumina and polymer binder at the same binder level and processing conditions. In mixed systems, bar strengths increased nearly in proportion to increases in polymer binder content over the 20‐40 per cent volume binder range. Parts made in any particular laser scanning mode showed optimum values for strength and density as the laser energy density was systematically increased from 2‐8cal/cm2. Suggests that optima result from the counteracting influences of energy density on binder fusion and thermal degradation. The optimum energy density is mode or geometry sensitive and shifts to lower values as the laser scanning vector is reduced. Concludes that this behaviour is probably the result of the lower heat losses. Equivalently better utilization of laser energy is associated with the shorter scan vectors. Some of the SLS fabricated bars were infiltrated with colloidal alumina, fired to remove the binder, and sintered at 1,600°C to achieve alumina bars with 50 per cent relative densities, interconnected porosity, and strengths between 2 and 8MPa.

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Rapid Prototyping Journal, vol. 1 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 March 1995

Mukesh Agarwala, David Bourell, Joseph Beaman, Harris Marcus and Joel Barlow

Considers efforts to date to produce parts by direct selective laser sintering (SLS) of metals, including post processing to improve structural integrity and/or to induce…

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Considers efforts to date to produce parts by direct selective laser sintering (SLS) of metals, including post processing to improve structural integrity and/or to induce a transformation. Provides a brief overview of the basic principles of SLS machine operation, and discusses materials issues affecting direct SLS of metals and the resultant properties and microstructures of the parts. Reviews results of past efforts on SLS of metal systems such as Cu‐Sn, Cu‐Solder (Pb‐Sn), Ni‐Sn, pre‐alloyed bronze (Cu‐Sn). Finally discusses more recent efforts on SLS of bronze‐nickel powder mixtures in greater detail.

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

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Article
Publication date: 1 June 1995

Mukesh Agarwala, David Bourell, Joseph Beaman, Harris Marcus and Joel Barlow

Gives a brief overview of post‐processing of selective laser sintered (SLS) metal parts to improve structural integrity and/or to induce a material transformation…

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Gives a brief overview of post‐processing of selective laser sintered (SLS) metal parts to improve structural integrity and/or to induce a material transformation. Presents results which show the effect of post‐processing liquid phase sintering temperature and time on material properties. Describes the hot isostatic pressing process, and discusses its application to SLS metal parts. Results gained from using this process show that it is suitable for achieving almost full‐density parts.

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Rapid Prototyping Journal, vol. 1 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 March 1974

Frances Neel Cheney

Communications regarding this column should be addressed to Mrs. Cheney, Peabody Library School, Nashville, Tenn. 37203. Mrs. Cheney does not sell the books listed here…

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Communications regarding this column should be addressed to Mrs. Cheney, Peabody Library School, Nashville, Tenn. 37203. Mrs. Cheney does not sell the books listed here. They are available through normal trade sources. Mrs. Cheney, being a member of the editorial board of Pierian Press, will not review Pierian Press reference books in this column. Descriptions of Pierian Press reference books will be included elsewhere in this publication.

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Reference Services Review, vol. 2 no. 3
Type: Research Article
ISSN: 0090-7324

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Article
Publication date: 1 April 1991

Allan Metz

This is a selective annotated bibliography of the literature on Christopher Columbus from 1970 to 1989. The subject is particularly relevant considering the approach of…

Abstract

This is a selective annotated bibliography of the literature on Christopher Columbus from 1970 to 1989. The subject is particularly relevant considering the approach of the Quincentenary of the “discovery” of America in 1992. For that same reason, there has been an outpouring of literature on the subject since 1990, a significant subset of which contributes to are interpretation of Columbus the man, his voyages, and their impact on the new world. It is hoped that this more recent literature will be part of a subsequent annotated bibliography.

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Reference Services Review, vol. 19 no. 4
Type: Research Article
ISSN: 0090-7324

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Article
Publication date: 1 January 1977

Beth Macleod and David Ginsburg

Although none of the new music reference books of the past year totally replaces the old stand‐bys, some significant works did appear, especially in the areas of…

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Although none of the new music reference books of the past year totally replaces the old stand‐bys, some significant works did appear, especially in the areas of contemporary music, opera, and classical music discography.

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Reference Services Review, vol. 5 no. 1
Type: Research Article
ISSN: 0090-7324

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Article
Publication date: 1 August 1944

THE hope we expressed in recent pages, that the Library Association might resume its normal methods of life and government, remains a hope. London, where only we suppose…

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THE hope we expressed in recent pages, that the Library Association might resume its normal methods of life and government, remains a hope. London, where only we suppose the Council could do its work really well, has been of late no place for the meetings of people; and we dare to say that for the key people of any profession or movement to gather there at present would be unwise, even though imagination may increase the risk beyond the warrant of the facts. Nor do we know yet if the worst has been experienced. Meanwhile it is probable that the affairs of librarianship must be delegated to even fewer workers than now. Only the chronically ungracious part of our fraternity will be without gratitude to those who keep things going for us.

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New Library World, vol. 47 no. 2
Type: Research Article
ISSN: 0307-4803

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