An analytical study of effects on aeroelasticity on control effectiveness

Various uses of the Elastic Stability Derivative (ELASRAD) program are described. Topics include structural influence coefficient matrices of wings, arrow wing structural analysis, and graphic display of wing structures. The rigid and elastic stability derivatives were calculated for Transonic Aircraft Technology Project aircraft

A theoretical investigation of the aerodynamics of low-aspect-ratio wings with partial leading-edge separation

A numerical method is developed to predict distributed and total aerodynamic characteristics for low aspect-ratio wings with partial leading-edge separation. The flow is assumed to be steady and inviscid. The wing boundary condition is formulated by the quasi-vortex-lattice method. The leading-edge separated vortices are represented by discrete free vortex elements which are aligned with the local velocity vector at mid-points to satisfy the force free condition. The wake behind the trailing-edge is also force free. The flow tangency boundary condition is satisfied on the wing, including the leading- and trailing-edges. Comparison of the predicted results with complete leading-edge separation has shown reasonably good agreement. For cases with partial leading-edge separation, the lift is found to be highly nonlinear with angle of attack

Flat-plate drag measurements with vortex generators in turbulent boundary layer

Direct drag measurements were obtained on a flat plate with a spanwise row of vortex generators near the leading edge, to produce an array of stream wise vortices within the approaching turbulent boundary layer. The object was to explore the possibility of modifying the large scale structure of the boundary layer through embedded longitudinal vortices with a view to obtaining a reduction in wall shear. Both obstacle and vane type vortex generators were tested at free stream velocities 40 ft/sec to 130 ft/sec corresponding to plate length Reynolds no. 0.3 million to 0.8 million with a nominal boundary layer thickness of approximately 0.6 in. at the leading edge. A few vortex generator configurations were tested both on and off the plate to measure the total drag as well as the plate drag alone. The obstacle type devices reduced the plate drag, indicating that the wake momentum defect predominated even in the presence of streamwise vortices. The vane type vortex generators however always increased the plate drag

A computer program for calculating aerodynamic characteristics of low aspect-ratio wings with partial leading-edge separation

The necessary information for using a computer program to predict distributed and total aerodynamic characteristics for low aspect ratio wings with partial leading-edge separation is presented. The flow is assumed to be steady and inviscid. The wing boundary condition is formulated by the Quasi-Vortex-Lattice method. The leading edge separated vortices are represented by discrete free vortex elements which are aligned with the local velocity vector at midpoints to satisfy the force free condition. The wake behind the trailing edge is also force free. The flow tangency boundary condition is satisfied on the wing, including the leading and trailing edges. The program is restricted to delta wings with zero thickness and no camber. It is written in FORTRAN language and runs on CDC 6600 computer

Effects of alarms on control of robot teams

Annunciator driven supervisory control (ADSC) is a widely used technique for directing human attention to control systems otherwise beyond their capabilities. ADSC requires associating abnormal parameter values with alarms in such a way that operator attention can be directed toward the involved subsystems or conditions. This is hard to achieve in multirobot control because it is difficult to distinguish abnormal conditions for states of a robot team. For largely independent tasks such as foraging, however, self-reflection can serve as a basis for alerting the operator to abnormalities of individual robots. While the search for targets remains unalarmed the resulting system approximates ADSC. The described experiment compares a control condition in which operators perform a multirobot urban search and rescue (USAR) task without alarms with ADSC (freely annunciated) and with a decision aid that limits operator workload by showing only the top alarm. No differences were found in area searched or victims found, however, operators in the freely annunciated condition were faster in detecting both the annunciated failures and victims entering their cameras' fields of view. Copyright 2011 by Human Factors and Ergonomics Society, Inc. All rights reserved

Mathematical modelling: A wonderful tool if Judiciously used

The excerpts of the lecture delivered by Prof. S.P. Mehrotra on the occassion of CSIR Diamond Jubilee Celebration

Tris(trimethyl-stannyl,-germyl, -sijyl)borates

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Computer Aided Design and Synthesis of Flotation Circuits

The design and synthesis of flotation circuits is conven-tionally based on rules of thumb derived from industrial practice. The heuristic approach is dependent on past experience and engineering judgement of experts. With the advent of relatively inexpensive computing power and easy availability of powerful optimization techniques, it is now possible to synthesize optimal multicomponent, multi-stage flotation separation base on rigorous quantitative analysis of alternate possibilities. For optimum synthesis of flotation circuits both cir-cuit. configuration as well as operating parameters are optimized simultaneously. Existing literature on circuit synthesis and optimization is broadly divided into two groups. While the literature pertaining to group one incor-porates the flotation models directly in the optimization models, those belonging to the second group use flotation models to characterize the constraints on component flows from a flotation bank only. The mass balance equation comprising the optimization models in the latter cate-gory are independent of flotation models. Recent advances in the field are reviewed in this paper

Mathematical Modelling of Contrinuous Casting of Steel Strips by Single Roll Process

Schematic representation of the Single Roll Continuous Casting of Steel Strips is shown in Figure 1. The liquid metal at a particular temperature Tl it held in the res-ervoir where the liquid metal level is always kept cons-tant. The metal continuously enters the annular space between the rotating chilled drut and the nozzle block through a graphite (refractory) nozzle. As soon as the molten metal comes in contact with the drum a skin of solid metal is formed which continues to grow as long as the liquid is in contact with this solidifies skin. Water at an input temperature TC extracts heat from the copper drum between the angles h and P2 . The drum rotates at an angular velocity W is anticlockwise directio