The history and ideas of pragmatism

This paper examines the origins of philosophical pragmatism in the USA in the second half of the 19th-century and its development and use up to the Second World War. The story is told through the lives and ideas of some of the main originators, Oliver Wendell Holmes Jr, Charles Saunders Peirce, William James and John Dewey. The core idea of pragmatism, that beliefs are guides to actions and should be judged against the outcomes rather than abstract principles, dominated American thinking during the period of economic and political growth from which the USA emerged as a world power. The paper suggests that the practical, commonsense, scientific approach embedded in pragmatism resonates with OR as practised and that much of pragmatism could be attractive to practitioners and academics alike.     

Ulrich line bundles on Enriques surfaces with a polarization of degree four

In this paper, we prove the existence of an Enriques surface with a polarization of degree four with an Ulrich bundle of rank one. As a consequence, we prove that general polarized Enriques surfaces of degree four, with the same numerical polarization class, carry Ulrich line bundles.     

The response of a plastic cylindrical shell to axial impact

Zusammenfassung Es wird eine Theorie des plastischen Knichens zylindrischer Schalen unter axialer Stossbelastung aufgestellt und eine Formel angegeben für die Stossgeschwindigkeiten, weilche in einer gegebenen Schale kleine Biegewellen erzeugen. Ferner wird eine einfache Berechnungsmethode für die Eigenfunktionen der Biegeschwingungen angegeben. Die Übereinstimmung der Theorie mit Versuchsergebnissen ist gut.     

The response of a thin elastic plate to a moving pressure point

Zusammenfassung Eine dünne unendliche elastische Platte sei plötzlich durch einen in einem Punkt konzentrierten Druck belastet, der sich danach auf einer Geraden mit konstanter Geschwindigkeitc bewegt. Unter Anwendung der elementaren Plattentheorie wird eine Integraldarstellung der Verbiegung hergeleitet. Dieses Integral kann in besonderen Fällen ausgewertet werden, insbesondere am Nullpunkt und unterhalb der sich bewegenden Last. Asymptotische Ergebnisse zeigen an, dass längs der Bahn des Druckpunktes grosse Plattenverbiegungen zu erwarten sind. Schliesslich wird die Lösung für die stationäre Punktbelastung als Grenzlösung des allgemeinen nicht-stationären Problems gefunden.

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Research sponsored by the Air Force Office of Scientific Research, Office of Aerospace Research, United States Air Force under AFOSR Grant No. 821-65.     

The response of a thin elastic rod to combined thermal and mechanical impulse

Zusammenfassung Es wird das Charakteristikenverfahren benützt, um zwei Probleme zu untersuchen, welche mit dem kombinierten Einfluss eines thermischen und mechanischen Stosses auf die Fortpflanzung einer elastischen Längswellenfront im eindimensionalen Körper zusammenhängen. Im ersten Fall werden die beiden Stösse gleichzeitig am freien Ende appliziert, und es werden die Änderungen in der Fortpflanzungsgeschwindigkeit studiert, welche auf das durch Diffusion erzeugte ungleichförmige Temperaturfeld zurückzuführen sind. Es wird gezeigt, dass die Vorläuferfront durch den modulierenden Effekt des Diffusionsprozesses in ihrer Intensität herabgesetzt wird. Das zweite Problem betrifft einen mechanischen Stoss, der einige Zeit nach Entstehen eines ungleichförmigen Temperaturfeldes infolge Wärmeflusses appliziert wird. Es werden Ausdrücke hergeleitet für die Modulation der Verzerrungen und Geschwindigkeiten an der Wellenfront, während die elastische Welle in ein festeres Medium hineinläuft.

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Presented at the Canadian Congress of Applied Mechanics, Laval University, May 22–26, 1967.     

The deliberative relevance of refraining from deciding: A response to McKenna and Pereboom

Readers familiar with Harry Frankfurt’s argument that we do not need leeway-liberty (or the power to bring about alternative possible actions or intentions) to be morally responsible will probably also know that the most famous and popular response on behalf of leeway-libertarianism remains a dilemma posed in similar forms by David Widerker, Robert Kane, and Carl Ginet: either the agent retains significant residual leeway in Frankfurt-style cases, or these cases beg the question by presupposing causal determinism. In the last few years, there have been several different attempts to defend Frankfurtian critiques of PAP in response this dilemma. In a novel approach, Derk Pereboom and Michael McKenna present cases in which all deliberatively relevant or “robust” alternatives are blocked, but the agent’s act or decision is not determined. Pereboom and McKenna argue that any plausible leeway-condition on responsibility must characterize the required alternatives as robust in two ways: being voluntary performances and having a practical relevance accessible to the agent’s mind. I agree with the requirement of robustness, and argue that we can build this notion into a complex concept of agent-possibility, or “agentive-can.” However, I argue that both McKenna’s and Pereboom’s conceptions of robustness are too demanding: they exclude alternatives that are intuitively relevant. Moreover, I argue that the alternative of refraining from deciding, or voluntarily failing to decide, is robust in the right sense. In agreement with a tradition running from Ockham back through Scotus to Aquinas, I argue that this robust alternative is necessary for responsibility. If the Frankfurt-controller eliminates it, then the agent’s responsibility is undermined. In particular, I argue that Pereboom’s tax evasion cases do not refute this leeway-condition on moral responsibility.     

Transient response of inhomogeneous thermoelastic media to a dynamic input

A problem involving a half-space or an infinite space with a cylindrical or spherical cavity subjected to a uniform dynamic input on its surface is studied. The material is elastic and has an inhomogeneity in the direction perpendicular to the boundary surface for the half-space problem and an inhomogeneity in the radial direction for the problem with a cylindrical or spherical cavity. The numerical results, obtained when the dynamic input is a step pressure, indicate that the wave profiles are influenced by two kinds of dispersions: one caused by thermal effects and the other by inhomogeneity. The influence of thermal dispersion is observed more pronouncedly along the initial portion of wave profiles. Compared to the homogeneous case the inhomogeneities in which Lamé's constants increase and decrease with the distance measured from the boundary have respectively amplifying and attenuating effects on both the axial stress and velocity.

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Zusammenfassung Das Problem der gleichmässigen dynamischen Belastung an den Grenzen eines halbunendlichen Körpers oder eines unendlichen Körpers mit einem zylindrischen oder sphärischen Halbraum wurde untersucht.Der Körper ist elastisch und enthält Inhomogenitäten, im halbunendlichen Körper in der Richtung senkrecht zur Grenzebene und im unendlichen Körper mit Hohlräumen in radialer Richtung. Die numerischen Ergebnisse, die für eine Belastung nach einer Schritt-Funktion erzielt wurden, zeigen dass die Profile der Ausbreitungswellen von zwei Streuungen beeinflusst sind: die erste ist eine Folge der thermischen Effekte, die zweite eine solche der Inhomogenitäten. Der Effekt der thermischen Zerstreuung ist im anfänglichen Bereich der Profile stärker. Im Vergleich zum homogenen Fall hat die Zu-beziehungsweise die Abnahme der Lamé'schen Konstanten mit dem Abstand von der Grenze erhöhenden beziehungsweise vermindernden Einfluss sowohl auf die axiale Spannung als auch auf die Geschwindigkeit.

     

The exact extreme response and the confidence extreme response analysis of structures subjected to uncertain-but-bounded excitations

In this study, the methods for computing the exact bounds and the confidence bounds of the dynamic response of structures subjected to uncertain-but-bounded excitations are discussed. Here the Euclidean norm of the nodal displacement is considered as the measurement of the structural response. The problem of calculating the exact lower bound, the confidence (outer) approximation and the inner approximation of the exact upper bound, and the exact upper bound of the dynamic response are modeled as three convex QB (quadratic programming with box constraints) problems and a problem of quadratic programming with bivalent constraints at each time point, respectively. Accordingly, the DCA (difference of convex functions algorithm) and the vertex method are adopted to solve the above convex QB problems and the quadratic programming problem with bivalent constraints, respectively. Based on the inner approximation and the outer approximation of the exact upper bound, the error between the confidence upper bound and the exact upper bound of dynamic response could be yielded. Specially, we also investigate how to obtain the confidence bound of the dynamic response of structures subjected to harmonic excitations with uncertain-but-bounded excitation frequencies. Four examples are given to show the efficiency and accuracy of the proposed method.     

Using Foucault to analyse ethics in the practice of problem structuring methods

As a new generation of problem-structuring methods (PSM) develops in operational research (OR) practice, the issue of ethics needs attention. This paper aims to contribute to examining ethics in the practice of problem structuring. The paper argues that PSM could influence ethical reflection but the scope of new developments is limited, as it is also the scope of ethical codes or norms in OR. Ethics needs to be understood as a continuous development by individuals in relation to existing frameworks and codes. This view of ethics is inspired by Michel Foucault's ideas on power and ethics. Using Foucault's ideas, two main areas of inquiry are suggested to enhance critical reflection about ethics: (a) individualization of forms of ethics, and (b) possibilities and constraints of ethics in power relations. Using these two areas, practitioners reflect on the ethics of their practice and relate it to their own ethical development.