16,456 research outputs found
First principles of project management - A review and commentary on Max Wideman's paper
The following thoughtful commentary on the original paper "First Principles of Project Management" presented on this site in November 2000, makes interesting reading and useful suggestions for improvement. Many of the comments derive from work done in preparing the authors' paper "The Underlying Theory of Project Management is Obsolete" presented to the Project Management's Research Conference in 200
The instability of a viscous sheet floating on an air cushion
The dynamics of a thin sheet of viscous liquid levitating on an air cushion is studied. Experimentally, it is observed that, after an initial settling stage, a local disturbance grows, eventually leading to the sheet blowing up like a viscous balloon. We derive a dynamical model for the levitating sheet and propose a mechanism for the onset of the instability. This instability is driven by the local drainage of the sheet due to a growing disturbance on its lower surface and is moderated by surface tension, the bending stiffness of the sheet and advection in the air layer. The balance between these effects determines the most unstable wavelength and this is illustrated by some numerical simulations
Fringe Science: Defringing CCD Images with Neon Lamp Flat Fields
Fringing in CCD images is troublesome from the aspect of photometric quality
and image flatness in the final reduced product. Additionally, defringing
during calibration requires the inefficient use of time during the night to
collect and produce a "supersky" fringe frame. The fringe pattern observed in a
CCD image for a given near-IR filter is dominated by small thickness variations
across the detector with a second order effect caused by the wavelength extent
of the emission lines within the bandpass which produce the interference
pattern. We show that essentially any set of emission lines which generally
match the wavelength coverage of the night sky emission lines within a bandpass
will produce an identical fringe pattern. We present an easy, inexpensive, and
efficient method which uses a neon lamp as a flat field source and produces
high S/N fringe frames to use for defringing an image during the calibration
process.Comment: accepted to PAS
Public Opinion in Perspective: Wisconsin's Mind on Education
Outlines survey findings on Wisconsin residents' views on the quality of public schools and reforms including increased spending, accountability, vouchers, charter schools, online education, and merit pay, compared with Milwaukee and national surveys
Miniaturized pointing mount performance analysis
Analytical analysis and computer simulation results of the miniaturized pointing mount as an instrument pointing system are presented. Miniaturized mount performance results include inertial pointing, slewing, tracking, and rastering. Typical instrument characteristics are used as well as some parameter variations of instrument and miniaturized pointing mount characteristics
Contracts and production
It is argued that a change in the prevailing theory of production is also influencing
how contracts, especially in construction, are being conceived. It is contended that the
theoretical shift in question, both in production and contracting, concerns the metaphysical
presuppositions of respective theories. This claim is further justified through a critical analysis
of how risks and collaboration between parties are considered in conventional contracting
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