Study of helicopterroll control effectiveness criteria

A study of helicopter roll control effectiveness based on closed-loop task performance measurement and modeling is presented. Roll control critieria are based on task margin, the excess of vehicle task performance capability over the pilot's task performance demand. Appropriate helicopter roll axis dynamic models are defined for use with analytic models for task performance. Both near-earth and up-and-away large-amplitude maneuvering phases are considered. The results of in-flight and moving-base simulation measurements are presented to support the roll control effectiveness criteria offered. This Volume contains the theoretical analysis, simulation results and criteria development

Yoga for generalized anxiety disorder: design of a randomized controlled clinical trial.

Generalized anxiety disorder (GAD) is a common disorder associated with significant distress and interference. Although cognitive behavioral therapy (CBT) has been shown to be the most effective form of psychotherapy, few patients receive or have access to this intervention. Yoga therapy offers another promising, yet under-researched, intervention that is gaining increasing popularity in the general public, as an anxiety reduction intervention. The purpose of this innovative clinical trial protocol is to investigate the efficacy of a Kundalini Yoga intervention, relative to CBT and a control condition. Kundalini yoga and CBT are compared with each other in a noninferiority test and both treatments are compared to stress education training, an attention control intervention, in superiority tests. The sample will consist of 230 individuals with a primary DSM-5 diagnosis of GAD. This randomized controlled trial will compare yoga (N=95) to both CBT for GAD (N=95) and stress education (N=40), a commonly used control condition. All three treatments will be administered by two instructors in a group format over 12 weekly sessions with four to six patients per group. Groups will be randomized using permuted block randomization, which will be stratified by site. Treatment outcome will be evaluated bi-weekly and at 6month follow-up. Furthermore, potential mediators of treatment outcome will be investigated. Given the individual and economic burden associated with GAD, identifying accessible alternative behavioral treatments will have substantive public health implications.R01 AT007257 - NCCIH NIH HHS; R01 AT007258 - NCCIH NIH HH

Mass Dependent Loss of Resolution in Radially Inhomogeneous ExB Ion Traps

ExB ion traps, such as Fourier transform Ion Cyclotron Resonance mass spectrometers (FY:ICR), mass analyze sample ions based on differences in their cyclotron frequencies in a homogeneous magnetic field. The high resolution mass measurements of FT-ICR are based on the relationship between the frequency of the cyclotron orbit and the mass-to-charge (m/q) ratio of an ion. Both the orbit and the frequency/mass relationship result from the radial forces on the ion. Ions trapped by inhomogeneous electric fields experience different magnitudes of the radial electric fields at different positions resulting in a positionally dependent frequency. Such differences in orbital frequencies for ions of a single m/q ratio result in line broadening and loss of resolution

Dynamical aspects of inextensible chains

In the present work the dynamics of a continuous inextensible chain is studied. The chain is regarded as a system of small particles subjected to constraints on their reciprocal distances. It is proposed a treatment of systems of this kind based on a set Langevin equations in which the noise is characterized by a non-gaussian probability distribution. The method is explained in the case of a freely hinged chain. In particular, the generating functional of the correlation functions of the relevant degrees of freedom which describe the conformations of this chain is derived. It is shown that in the continuous limit this generating functional coincides with a model of an inextensible chain previously discussed by one of the authors of this work. Next, the approach developed here is applied to a inextensible chain, called the freely jointed bar chain, in which the basic units are small extended objects. The generating functional of the freely jointed bar chain is constructed. It is shown that it differs profoundly from that of the freely hinged chain. Despite the differences, it is verified that in the continuous limit both generating functionals coincide as it is expected.Comment: 15 pages, LaTeX 2e + various packages, 3 figures. The title has been changed and three references have been added. A large part of the manuscript has been rewritten to improve readability. Chapter 4 has been added. It contains the construction of the generating functional without the shish-kebab approximation and a new derivation of the continuous limit of the freely jointed bar chai

Book Reviews

BOOK REVIEWS The Swiss Way of Welfare: Lessons for the Western World. Ralph Segalman. New York: Praeger, 1986, 205 pp., $39.95. - Reviewed by Isidor Walliman Vieillesses: Situations, Itineraires et Modes de Vie des Personnes Agees Aujourd\u27Hui. Christian Lalive d\u27Epiany (Ed.). Saint Saphorin, Switzerland: Edition Georgi, 1983. - Reviewed by Elizabeth D. Huttman with the assistance of Anna Marie Rampmaier and W and N. Weber. Wohlfahrtsstaat Schweiz (The Swiss Welfare State). Antonin Wagner. Bern: Paul Haupt, 1985, 248 pp., S.E 32. - Reviewed by Shimon S. Gottschalk The Mean Season: The Attack on the Welfare State. Fred Block, Richard A. Cloward, Barbara Ehrenreich, Frances Fox Piven. New York: Pantheon Books, 1987, 205 pp.,$8.95. - Reviewed by Robert Sheak Shared Responsibility: Families and Social Policy. Robert M. Moroney. Hawthorne, N.Y.: Aldine Publishing Co., 1986, $31.95 cloth,$14.94 paper. - Reviewed by Christina R. Curtiss

Bis(tetra­methyl­ammonium) tetra­chlorido­zincate(II), phase VI

Phase VI of bis­(tetra­methyl­ammonium) tetra­chloro­zincate(II), (C4H12N)2[ZnCl4], contains three formula units per asymmetric unit. Several short C—H⋯Cl contacts [2.70 (3) and 2.72 (4) Å] are observed, but they are believed to participate only in van der Waals inter­actions. The crystal studied exhibited inversion twinning

Eulerian simulation of the fluid dynamics of helicopter brownout

A computational model is presented that can be used to simulate the development of the dust cloud that can be entrained into the air when a helicopter is operated close to the ground in desert or dusty conditions. The physics of this problem, and the associated pathological condition known as ‘brownout’ where the pilot loses situational awareness as a result of his vision being occluded by dust suspended in the flow around the helicopter, is acknowledged to be very complex. The approach advocated here involves an approximation to the full dynamics of the coupled particulate-air system. Away from the ground, the model assumes that the suspended particles remain in near equilibrium under the action of aerodynamic forces. Close to the ground, this model is replaced by an algebraic sublayer model for the saltation and entrainment process. The origin of the model in the statistical mechanics of a distribution of particles governed by aerodynamic forces allows the validity of the method to be evaluated in context by comparing the physical properties of the suspended particulates to the local properties of the flow field surrounding the helicopter. The model applies in the Eulerian frame of reference of most conventional Computational Fluid Dynamics codes and has been coupled with Brown’s Vorticity Transport Model. Verification of the predictions of the coupled model against experimental data for particulate entrainment and transport in the flow around a model rotor are encouraging. An application of the coupled model to analyzing the differences in the geometry and extent of the dust clouds that are produced by single main rotor and tandem-rotor configurations as they decelerate to land has shown that the location of the ground vortex and the size of any regions of recirculatory flow, should they exist, play a primary role in governing the extent of the dust cloud that is created by the helicopter