Examination of returned solar-max surfaces for impacting orbital debris and meteoroids

Previous theoretical studies predicted that in certain regions of earth orbit, the man-made earth orbiting debris environment will soon exceed the interplanetary meteoroid environment for sizes smaller than 1 cm. The surfaces returned from the repaired Solar Max Mission (SMM) by STS 41-C on April 12, 1984, offered an excellent opportunity to examine both the debris and meteoroid environments. To date, approximately 0.7 sq. met. of the thermal insulation and 0.05 sq. met of the aluminum louvers have been mapped by optical microscope for crater diameters larger than 40 microns. Craters larger in diameter than about 100 microns found on the initial 75 micron thick Kapton first sheet on the MEB (Main Electronics Box) blanket are actually holes and constitute perforations through that blanket. The following populations have been found to date in impact sites on these blankets: (1) meteoritic material; (2) thermal paint particles; (3) aluminum droplets; and (4) waste particles

R&D, Agency Costs and Capital Structure: International Evidence

We examine the impact of R&D intensity and agency costs on the value of firms across 13 economies. We find that R&D adds value while high agency costs reduce value. R&D adds value, however, even when agency costs are high. We show that in those firms where agency costs are high and R&D intensity is high the debt control hypothesis is at work. In contrast to the stylised fact of high R&D firms having low levels of debt, these firms have higher levels of debR&D, Agency Costs, Capital Structure

Small Effects in Astrophysical Fusion Reactions

We study the combined effects of vacuum polarization, relativity, Bremsstrahlung, and atomic polarization in nuclear reactions of astrophysical interest. It is shown that these effects do not solve the longstanding differences between the experimental data of astrophysical nuclear reactions at very low energies and the theoretical calculations which aim to include electron screening.Comment: 13 pages, 1 figur

Preliminary design of debris removal missions by means of simplified models for low-thrust, many-revolution transfers

This paper presents a novel approach for the preliminary design of Low-Thrust (LT), many-revolution transfers. The main feature of the novel approach is a considerable reduction in the control parameters and a consequent gain in computational speed. Each spiral is built by using a predefined pattern for thrust direction and switching structure. The pattern is then optimised to minimise propellant consumption and transfer time. The variation of the orbital elements due to the propulsive thrust is computed analytically from a first-order solution of the perturbed Keplerian motion. The proposed approach allows for a realistic estimation of ΔV cost and time of flight required to transfer a spacecraft between two arbitrary orbits. Eccentricity and plane changes are both taken into account. The novel approach is applied here to the design of missions for the removal of space debris by means of an Ion Beam Shepherd (IBS) Spacecraft. In particular, two slightly different variants of the proposed low-thrust control model are used for the two main phases of the debris removal mission, i.e. the rendezvous with the target object and its removal. Thanks to their relatively low computational cost they can be included in a multiobjective optimisation problem in which the sequence and timing of the removal of five hypothetical pieces of debris are optimised in order to minimise both propellant consumption and mission duration

Two reasons why epistemic reasons are not object-given reasons

In this paper I discuss two claims; the first is the claim that state-given reasons for belief are of a radically different kind to object-given reasons for belief. The second is that, where this last claim is true, epistemic reasons are object-given reasons for belief (EOG). I argue that EOG has two implausible consequences: (i) that suspension of judgement can never be epistemically justified, and (ii) that the reason that epistemically justifies a belief that p can never be the reason for which one believes that p

Investigations of the potential performance characteristics of selected contact lubricants for applications in miniature slip-ring capsules of the type used in ST 124 M stabilized inertial guidance platforms Final technical report, 27 Mar. 1968 - 30 Apr. 1970

Performance characteristics of liquid and solid lubricants for contacts of miniature slip-ring capsule

Recovering from the Global Financial Crisis:Achieving Financial Stability in Times of Uncertainty

Why are some global financial crises more difficult to recover from and overcome than others? What steps are necessary in ensuring that financial stability and recovery is facilitated? What kind of environment has the previous financial environment evolved to and what kind of financial products have also contributed to greater vulnerability in the triggering of systemic risks? These are amongst some of the questions which this book attempts to address. In highlighting the role and importance of various actors in post crises reforms and the huge impacts certain factors and products have contributed in exacerbating the magnitude and speed of transmission of financial contagion, it also provides an insight into why global financial crises have become more complicated to address than was previously the case. As well as considering and highlighting why matters related to pro cyclicality and capital measures should not constitute the sole focus of attention of the G20's initiatives, the book is aimed at identifying other important issues such as liquidity risks and requirements which have constituted, to a large extent, the focus of international standard setters and regulators. It also aims to direct regulators, central bank officials and supervisors, academics, business and legal professionals and other relevant interested parties in the field to current and previously ignored issues such as the "cartelisation" of capital markets. The need and concern for increased regulation of bond, equity markets, as well as other complex financial instruments which can be traded in OTC (Over-the-Counter) derivatives markets is evidenced by Basel III's focus. "Cartelisation" and organised activities relating to rate rigging in global capital markets have been evidenced recently by sophisticated EURIBOR and LIBOR rate rigging practices and occurences. The aims and objectives of the book would not be complete by merely identifying and highlighting the general root causes of global financial crises, and current issues to be focussed on. Hence each chapter will also recommend (as well as highlight) measures which should be (and have been) put forward in order to address the issues and factors which contribute to the magnitude and severity of global financial crises

OSO head and tape studies Final report

OSO recording head and tape studie

Dewetting of thin-film polymers

In this paper we present a theoretical model for the dewetting of ultra-thin polymer films. Assumming that the shear-thinning properties of these films can be described by a Cross-type constitutive equation, we analyze the front morphology of the dewetting film, and characterize the time evolution of the dry region radius, and of the rim height. Different regimes of growth are expected, depending on the initial film thickness, and on the power-law index involved in the constitutive equation. In the thin-films regime, the dry radius and the rim height obey power-law time dependences. We then compare our predictions with the experimental results obtained by Debr\'egeas {\it et al.} [Phys. Rev. Lett. {\bf 75}, 3886 (1995)] and by Reiter [Phys. Rev. Lett. {\bf 87}, 186101 (2001)].Comment: 12 pages, 14 figure