327 research outputs found

    International Cometary Explorer (ICE)

    Get PDF
    The primary mission objectives of the International Cometary Explorer (ICE) Comet Mission are to determine the composition and physical state of the Giacobini-Zinner Comet's nucleus; to determine the processes that governs the composition and distribution of neutral and ionized species in the cometary atmosphere; and to investigate the interaction between the solar wind and the cometary atmosphere. The spacecraft was in a halo orbit around the Sun-Earth libration point until it was moved 10 Jun. 1982 to the Earth's Geomagnetic Tail (GT). The spacecraft reached the GT in Jan. 1983 and remained there until Dec. 1983, at which time a lunar swing-by placed the spacecraft in a trajectory heliocentric orbit which encountered the comet Giacobini-Zinner in Sep. 1985. The spacecraft provided observations of solar wind upstream of Halley's Comet in 1986. Information is presented in tabular form and includes the following areas: Deep Space Network support, frequency assignments, telemetry, command, and tracking support responsibilities

    At what time does a quantum experiment have a result?

    Get PDF
    This paper provides a general method for defining a generalized quantum observable (or POVM) that supplies properly normalized conditional probabilities for the time of occurrence (i.e., of detection). This method treats the time of occurrence as a probabilistic variable whose value is to be determined by experiment and predicted by the Born rule. This avoids the problematic assumption that a question about the time at which an event occurs must be answered through instantaneous measurements of a projector by an observer, common to both Rovelli (1998) and Oppenheim et al. (2000). I also address the interpretation of experiments purporting to demonstrate the quantum Zeno effect, used by Oppenheim et al. (2000) to justify an inherent uncertainty for measurements of times.Comment: To appear in proceedings of 2015 ETH Zurich Workshop on Time in Physic

    exit the immune system

    Get PDF

    Earth Radiation Budget Satellite (ERBS): Emergency support

    Get PDF
    The primary purpose of the Earth Radiation Budget Satellite (ERBS) project is to study the Earth's atmospheric processes and their relationship to the Earth's climate. Following deployment from the Space Shuttle, the satellite was maneuvered into a circular orbit of 610 km x 610 km x 57 degrees, with a period of 99.6 minutes. The Deep Space Network (DSN) will support the ERBS during emergency situations in the event that the standard Tracking and Data Relay Satellite System (TDRSS) to White Sands data link is inoperative. Emergency support will be provided by the DSN's 26-meter antenna subnetwork. Information is given in tabular form for DSN network support, frequency assignments, telemetry, and command

    Dynamics Explorer-1 (DE-1)

    Get PDF
    The Dynamics Explorer (DE) mission is designed to study the Earth's electromagnetic fields at varying heights up to 4 Earth radii. The DE-1 was launched on a Delta 3913 launch vehicle from the Western Test Range and was placed in a 561 x 23279 km orbit with a 90 degree inclination. The Deep Space Network (DSN) began to support this extended mission on February 1, 1985. Coverage consists of five passes per day that last for 45 minutes each. Information is given in tabular form for DSN support, frequency assignments, telemetry, command, and tracking mission responsibility

    The effect of laser transformation notching on the controlled fracture of a high carbon (C70S6 ) steel

    Get PDF
    A high carbon (C70S6) steel has been laser surface treated using CO2 and Diode lasers in order to produce an embrittled region to act as a fracture notch. Such a process has been investigated as a precursor to the fracture splitting of automotive engine connecting rods. Microstructures of the treated regions have been examined and the fracture behaviour of notched samples has been quantified. Depending on the laser processing parameters used, the laser transformation notch (LTN) undergoes either solid state transformations or a mixture of melting and solid state transformations. The effect of LTN depth on the peak impact force, the crack initiation energy and Charpy fracture energy was investigated on a C70S6 carbon steel using an instrumented Charpy impact facility. It was reduced to a value < 3.5 J by a LTN of ~ 0.5 mm in depth. Fracture mechanics models indicate that such a LTN can behave in a similar way to a fatigue created crack used in fracture toughness testing ie the LTN behaves as a sharp crack. Obtaining a sharp crack effect from a LTN is attributable to a combination of: a) the presence of brittle martensite, b) intergranular cracking of favourably oriented columnar grains after melting with inclusions and defects at their boundaries, c) intergranular cracking of coarse grains produced by a high austenitising temperatures and d) minor or major cracks sometimes resulting in centre – line cracking which arises during solidification. LTN was thus shown to have the potential to lead to an effective means of obtaining consistent fracture splitting of connecting rods

    How Do Things Persist? Location Relations in Physics and the Metaphysics of Persistence

    Get PDF
    This paper investigates the use of theories of mechanics (classical and quantum) to provide answers to questions in the metaphysics of spatial location and persistence. Investigating spatial location, I find that in classical physics bodies pertend the region of space at which they are exactly located, while a quantum system spans a region at which it is exactly located. Following this analysis, I present a ‘no-go’ result which shows that quantum mechanics (conventionally interpreted) restricts the available options for locational persistence theories in an interesting way: it demonstrates that the spatiotemporal path of a persisting thing is discrete (or discontinuous) in time. This leads to unpalatable consequences for both perdurantists and endurantists. In particular, I argue that Butterfield’s ‘anti-pointilliste’ perdurantism is ruled out, and show that endurantists relying on immanent causation run into trouble. I conclude by suggesting the revival of Whitehead’s alternative mode of persistence called ‘reiteration.

    Conflations, possibilities, and foreclosures: Global citizenship education in a multicultural context

    Get PDF
    © 2015 the Ontario Institute for Studies in Education. This paper presents a critical framework applied to findings from a critical discourse analysis of curriculum and lesson plans in Alberta to examine the assumption that Canada is an ideal place for global citizenship education. The analysis draws on a framework that presents a critique of modernity to recognize a conflation within calls for new approaches to educating citizens for the twenty-first century. A main finding is that although the Alberta curriculum reflects important potential for promoting a critical approach, a conflation of different versions of liberalism often results in a false sense of multiple perspectives and a foreclosure of potential. The paper argues for a critical approach to global citizenship education that engages with the tensions inherent to issues of diversity rather than stepping over or reducing them to theoretically and conceptually vague ideas of universalism and consensus

    achievement

    Get PDF

    Global, Citizenship and Education as Discursive Fields: Towards Disrupting the Reproduction of Colonial Systems of Power

    Get PDF
    Drawing together a broad range of contributors and cutting edge research the volume offers chapters that seek to reflect the full spectrum of approaches and topics, providing a valuable resource which highlights the value of an extended and thoughtful study of the idea and practice of global citizenship within a broader consideration of the processes of globalization. It will be of great use to graduates and scholars of international relations, sociology, and global studies/affairs, as well as globalization
    corecore