18,213 research outputs found

    Development and application of a unified balancing approach with multiple constraints

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    The development of a general analytic approach to constrained balancing that is consistent with past influence coefficient methods is described. The approach uses Lagrange multipliers to impose orbit and/or weight constraints; these constraints are combined with the least squares minimization process to provide a set of coupled equations that result in a single solution form for determining correction weights. Proper selection of constraints results in the capability to: (1) balance higher speeds without disturbing previously balanced modes, thru the use of modal trial weight sets; (2) balance off-critical speeds; and (3) balance decoupled modes by use of a single balance plane. If no constraints are imposed, this solution form reduces to the general weighted least squares influence coefficient method. A test facility used to examine the use of the general constrained balancing procedure and application of modal trial weight ratios is also described

    A comparison of different indicators of chaos based on the deviation vectors. Application to symplectic mappings

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    The aim of this research work is to compare the reliability of several variational indicators of chaos on mappings. The Lyapunov Indicator (LI); the Mean Exponential Growth factor of Nearby Orbits (MEGNO); the Smaller Alignment Index (SALI); the Fast Lyapunov Indicator (FLI); the Dynamical Spectra of stretching numbers (SSN) and the corresponding Spectral Distance (D); and the Relative Lyapunov Indicator (RLI), which is based on the evolution of the difference between two close orbits, have been included. The experiments presented herein allow us to reliably suggest a group of chaos indicators to analyze a general mapping. We show that a package composed of the FLI and the RLI (to analyze the phase portrait globally) and the MEGNO and the SALI (to analyze orbits individually) is good enough to make a description of the systems' dynamics.Comment: 25 pages, 40 figures. Celestial Mechanics and Dynamical Astronomy, in pres

    Some Cognitive Transformations About the Dynamics of Desistance

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    This article explores the role of cognitive transformations in the process of desistance from crime. Based on our own and others’ subsequent research, clearly, some aspects of our initial theorizing warrant revisiting and adjustment. The discussion describes changes to ideas about the sequencing of various types of cognitive shifts, suggests the importance of emotional processes in tandem with changes in perspective, and highlights the need to move out of the comfort zone of crime itself when thinking about redefinitions that support desistance. Yet, a consistent notion remains that social and broader structural factors are deeply implicated—directly and indirectly—in all aspects of the change process. This includes the important area of “derailments” from a pattern of forward progress, where additional processual research is needed. The discussion concludes with the argument that individualistic policies and programs centered on cognitive deficits requiring correction are likely to be limited in their effectiveness
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