Robust Control Design for Large Space Structures

The control design problem for the class of future spacecraft referred to as large space structures (LSS) is by now well known. The issue is the reduced order control of a very high order, lightly damped system with uncertain system parameters, particularly in the high frequency modes. A design methodology which incorporates robustness considerations as part of the design process is presented. Combining pertinent results from multivariable systems theory and optimal control and estimation, LQG eigenstructure assignment and LQG frequency shaping, were used to improve singular value robustness measures in the presence of control and observation spillover

MARKETING EFFICIENCY AND EQUITY: A CASE STUDY OF AN AREA'S COTTON GINNING INDUSTRY

Marketing,

Report on Screw Fastened Sheet Steel Connections for Canadian Steel Industries Construction Council, Volume I

Ultimate load data is presented from more than 1600 tests on sample connections made with different thicknesses of zinc-coated sheet steel and a variety of commonly used thread forming and self-drilling fasteners. The three fundamental loading conditions examined were pull-over, pull-out and single lap shear. Empirical relationships have been developed which allow interpolation of the data within the range of sheet steel thicknesses tested. Type AB and type A thread forming fasteners, and a number of different self-drilling fasteners were tested, in sizes from #14 (.250 in.) to #8 (.164 in.) diameter. Flat metal washers and a variety of sealing washers were also used in combination with the different fastener types and head styles. The thicknesses of steel sheets ranged from .022 in. to .060 in. depending on the particular loading condition being tested. The sheet material was ductile and of medium strength and hardness. All fastener connections tested under all loading conditions achieved higher failure loads with thicker steel sheets. The #14 (.250 in.) diameter fasteners of each type gave significantly higher connection failure loads in most sheet thicknesses than the other fastener sizes. Connections with #12 (.216 in.), #10 (.190 in.) and #8 (.164 in.) diameter fasteners showed only marginal differences in ultimate load

Genomic analyses of Paenibacillus polymyxa CR1, a bacterium with potential applications in biomass degradation and biofuel production

Lignin is a polyphenolic heteropolymer constituting between 18 to 35% of lignocellulose and is recognized as preventative of cellulosic biofuel commercialization. Paenibacillus polymyxa CR1 was isolated from naturally degrading corn stover and shown to produce alcohols using lignin as a sole carbon source. Genome sequencing and comparative genomics of P. polymyxa CR1 identified two homologs, a Dyp-type peroxidase and a laccase, which have previously been implicated in lignin metabolism in other bacteria. Knockout mutants of the identified genes displayed no growth deficiency and P. polymyxa CR1 is incapable of metabolizing common aromatic intermediates of lignin, suggesting the bacterium employs a novel catabolic pathway. To identify genes involved in lignin metabolism, a transposon library was generated and screened for abnormal lignin growth phenotypes. The results contained within will help elucidate the genetic basis of known functions helping delineate regulatory pathways and metabolic versatility in P. polymyxa relevant to lignin metabolism

Entrepreneurship and Obsolescence: Owen W. Davis, Jr. and The Katahdin Charcoal Iron Company 1876-1890

This article discusses the efforts of Owen Davis in charcoal iron making in an antiquated plant in a remote and underdeveloped section of northern Maine