4,460 research outputs found

    Fixed-Base Simulator Studies of the Ability of the Human Pilot to Provide Energy Management Along Abort and Deep-Space Entry Trajectories

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    A simulation study has been made to determine a pilot's ability to control a low L/D vehicle to a desired point on the earth with initial conditions ranging from parabolic orbits to abort conditions along the boost phase of a deep-space mission. The program was conducted to develop procedures which would allow the pilot to perform the energy management functions required while avoiding the high deceleration or skipout region and to determine the information display required to aid the pilot in flying these procedures. The abort conditions studied extend from a region of relatively high flight-path angles at suborbital velocities while leaving the atmosphere to a region between orbital and near-escape velocity outside the atmosphere. The conditions studied included guidance from suborbital and superorbital aborts as well as guidance following return from a deepspace mission. In this paper, the role of the human pilot?s ability to combine safe return abort procedures with guidance procedures has been investigated. The range capability from various abort and entry conditions is also presented

    A comparison of laser based ranging systems for AR/C category 1: Hardware

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    This paper will present some aspects of the effect of inherent laser effects on the performance of CW-Tone modulated and FM-CW laser ranging techniques. It will be shown that performance of these techniques is affected in different ways by inherent laser characteristics and previous comparisons of the techniques should be modified to reflect more realistic conditions. An overall survey of laser ranging will be given to place the CW and FM-CW techniques in perspective. It will be seen that the newly introduced FM-CW laser radar has potentially far superior performance to CW-Tone modulated systems now proposed for use in space rendezvous and capture systems

    A comparison of laser-based ranging systems for AR/C

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    The three most common types of laser target ranging (time-of-flight, tone modulated, and FM-CW) are discussed in terms of principle of operation. The first, time-of-flight, is shown to depend more on the ability of support electronics than the fundamentals of the concept. Examples in the literature are cited to show the remarkably good performance of time-of-flight systems. A system developed in Finland was shown to have an incremental ranging capability of a few millimeters. The system is not only robust; it does not include additions such as reference legs and the like, which are expected, for improvement in performance. Though not immediately obvious, the second technique, tone modulated ranging is somewhat of an extension of the time-of-flight technique. Finally, the FM-CW technique is presented. This is completely different from the tone or time-of-flight techniques, but is a direct translation of the same-named technique used in radar ranging systems

    State Intervention and the Family: Problems of Policy

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    Russia’s Ministry of Ambivalence:The Failure of Civic Nation-Building in Post-Soviet Russia

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    This article argues that the sources of official and societal ambivalence towards civic nationhood in today’s Russia are found in the institutional instability and personalist dynamics of hybrid regime politics in the 1990s. Successful civic nation-building should institutionalize inclusive criteria for citizenship as a basis for policymaking, which in turn should create incentives for dominant ethnicities to embrace civic nationhood. While the shifting views of Boris Yel’tsin on nationalities policy and the constant turmoil in the government’s nationalities ministry have received little scholarly attention, they illuminate the endogenous sources of regime instability in relation to civic nation-building. Russia’s experience thus challenges the traditional view of ethnic nationalism as fostering authoritarianism and civic nationalism as fostering democracy: rather, competitive authoritarianism in the 1990s confounded the regime’s own efforts toward civic nation-building and laid the groundwork for the “ethnic turn” in Russian politics under Vladimir Putin.</p

    A Phase Space Approach to Gravitational Enropy

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    We examine the definition S = ln Omega as a candidate "gravitational entropy" function. We calculate its behavior for gravitationl and density perturbations in closed, open and flat cosmologies and find that in all cases it increases monotonically. Using the formalism to calculate the gravitational entropy produced during inflation gives the canonical answer. We compare the behavior of S with the behavior of the square of the Weyl tensor. Applying the formalism to black holes has proven more problematical.Comment: Talk delivered at South African Relativistic Cosmology Symposium, Feb 1999. Some new results over Rothman and Anninos 97. To appear in GRG, 17 page

    An algorithm for linearly constrained nonlinear programming problems

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    AbstractIn this paper an algorithm for solving a linearly constrained nonlinear programming problem is developed. Given a feasible point, a correction vector is computed by solving a least distance programming problem over a polyhedral cone defined in terms of the gradients of the “almost” binding constraints. Mukai's approximate scheme for computing the step size is generalized to handle the constraints. This scheme provides an estimate for the step size based on a quadratic approximation of the function. This estimate is used in conjunction with Armijo line search to calculate a new point. It is shown that each accumulation point is a Kuhn-Tucker point to a slight perturbation of the original problem. Furthermore, under suitable second order optimality conditions, it is shown that eventually only one trial is needed to compute the step size

    OncoLog Volume 41, Number 03, July-September 1996

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    M. D. Anderson researchers stress importance of annual colorectal cancer screening Informed consent explains concerns about genetic testing New program focuses on inherited predisposition to breast and ovarian cancerhttps://openworks.mdanderson.org/oncolog/1055/thumbnail.jp

    Building from the Ground Up: Creating Effective Programs to Mentor Children of Prisoners (The Amachi Model)

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    Drawing from P/PVs five years of hands-on experience designing and implementing Amachi programs around the country, Building From The Ground Up describes best practices for planning, developing and managing a mentoring-children-of-prisoners program. This guidebook is essential for learning the professional procedures, standards and administrative tools required to have an effective program
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