title: Necessary connections between distinct existences: A Peircean challenge to Humeanism

authors: Legg, Catherine

subjects: Peirce

abstract: It is hard to overestimate the impact of Hume’s famous dictum: “There are no necessary connections between distinct existences” on the subsequent development of mainstream philosophy. It has not only influenced philosophical thinking about causation, laws of nature and other areas of ‘scientific metaphysics’, but also modality, mathematics, personal identity and very importantly, ethics. But is it true? I argue that Hume uses the supposed axiomatic status of his dictum as a covert means of denying - whilst avoiding an honest metaphysical debate about - the view of scholastic realism. I discuss how Peirce by contrast engaged in this debate, and some of his conclusions.

text: Necessary connections between distinct existences: A Peircean challenge to Humeanism It is hard to overestimate the impact of Hume’s famous dictum: “There are no necessary connections between distinct existences” on the subsequent development of mainstream philosophy. It has not only influenced philosophical thinking about causation, laws of nature and other areas of ‘scientific metaphysics’, but also modality, mathematics, personal identity and very importantly, ethics. But is it true? I argue that Hume uses the supposed axiomatic status of his dictum as a covert means of denying - whilst avoiding an honest metaphysical debate about - the view of scholastic realism. I discuss how Peirce by contrast engaged in this debate, and some of his conclusions.

year: 2012

title: Simulation of the powder forging process for titanium components using a porous metal plasticity model

authors: Velluvakkandi, Navaneeth

subjects: powder forging

abstract: Powder forging is a technique that has been used to produce fully dense near-net parts from metal powders.  Due to a “low cost titanium” product manufacturing initiative, targeting a reduction in the cost of titanium components, a titanium powder forging technique has gained significant interest.  In titanium powder forging, powder consolidation is a key factor that influences successful component manufacture.  Consolidation during titanium powder forging is dependent on the densification and deformation mechanisms involved.
In this study, a finite element method is used to model the densification and deformation behaviour of titanium powder compacts during powder forging.  The research focuses on developing a simulation capability and identifying a suitable constitutive model to simulate the powder forging process that can predict the relative density distribution.  The simulation is carried out in Abaqus software and the results are compared with experimental results.  A gamma particle radiography technique is used to compare the experimental density results with the simulated results.
The Gurson and Gurson-Tvergaard models are used to predict the relative density of porous titanium powder compacts during upset-powder forging and are used to include the effect of hydrostatic stresses and the extent of densification.  Three different modes of densification, related to powder forging were studied i.e. upset forging, hot-repressing and closed die forging.
The simulation results indicate that both models can be used to determine the relative density during powder forging.  By comparing the simulated results with the experimental results, it is found that the density prediction given by the Gurson-Tvergaard model showed closer agreement with the calculated parameters.

text: Simulation of the powder forging process for titanium components using a porous metal plasticity model Powder forging is a technique that has been used to produce fully dense near-net parts from metal powders.  Due to a “low cost titanium” product manufacturing initiative, targeting a reduction in the cost of titanium components, a titanium powder forging technique has gained significant interest.  In titanium powder forging, powder consolidation is a key factor that influences successful component manufacture.  Consolidation during titanium powder forging is dependent on the densification and deformation mechanisms involved.
In this study, a finite element method is used to model the densification and deformation behaviour of titanium powder compacts during powder forging.  The research focuses on developing a simulation capability and identifying a suitable constitutive model to simulate the powder forging process that can predict the relative density distribution.  The simulation is carried out in Abaqus software and the results are compared with experimental results.  A gamma particle radiography technique is used to compare the experimental density results with the simulated results.
The Gurson and Gurson-Tvergaard models are used to predict the relative density of porous titanium powder compacts during upset-powder forging and are used to include the effect of hydrostatic stresses and the extent of densification.  Three different modes of densification, related to powder forging were studied i.e. upset forging, hot-repressing and closed die forging.
The simulation results indicate that both models can be used to determine the relative density during powder forging.  By comparing the simulated results with the experimental results, it is found that the density prediction given by the Gurson-Tvergaard model showed closer agreement with the calculated parameters.

year: 2014

title: Radiocarbon dates on desiccated moa (Dinornithiformes) flesh from Inland Otago, New Zealand

authors: Anderson, Atholl

subjects: New Zealand

abstract: Remains of soft tissues from extinct moa (Dinornithiformes), mainly desiccated sinew, muscle, skin, and feathers have been recovered rather seldom but their distribution is distinctive. Of 22 records of such finds accumulated between 1864 and 1987, 15 came from inland Otago (Anderson 1989: 67–68, Table 5.2), west of Dunedin in the southern South Island. Most were found in the late nineteenth century (13 records) in rockshelters, clefts or alluvial sediments and were regarded at the time as evidence of the survival of moa up to about AD 1800 (Hutton and Coughtrey 1874a). Improbable as this latter point is, it has not been tested by radiocarbon dating until now. Our particular impetus to do so, however, arises in another way. It is from research, again largely within inland Otago, on Maori artefacts which have also been made from various other kinds of soft tissues (flax, grasses, dog skin, bird skin, feathers etc.). A series of accelerator mass spectrometry (AMS) radiocarbon dates on these (Anderson et al., n.d.) shows that they are exclusively late, post-AD 1650, which begs the question of why the age range does not extend across the full prehistoric period, beginning about AD 1300.

text: Radiocarbon dates on desiccated moa (Dinornithiformes) flesh from Inland Otago, New Zealand Remains of soft tissues from extinct moa (Dinornithiformes), mainly desiccated sinew, muscle, skin, and feathers have been recovered rather seldom but their distribution is distinctive. Of 22 records of such finds accumulated between 1864 and 1987, 15 came from inland Otago (Anderson 1989: 67–68, Table 5.2), west of Dunedin in the southern South Island. Most were found in the late nineteenth century (13 records) in rockshelters, clefts or alluvial sediments and were regarded at the time as evidence of the survival of moa up to about AD 1800 (Hutton and Coughtrey 1874a). Improbable as this latter point is, it has not been tested by radiocarbon dating until now. Our particular impetus to do so, however, arises in another way. It is from research, again largely within inland Otago, on Maori artefacts which have also been made from various other kinds of soft tissues (flax, grasses, dog skin, bird skin, feathers etc.). A series of accelerator mass spectrometry (AMS) radiocarbon dates on these (Anderson et al., n.d.) shows that they are exclusively late, post-AD 1650, which begs the question of why the age range does not extend across the full prehistoric period, beginning about AD 1300.

year: 2010