8,477 research outputs found
Proportional-integral-plus (PIP) control of the ALSTOM gasifier problem
Although it is able to exploit the full power of optimal state variable feedback within a non-minimum state-space (NMSS) setting, the proportional-integral-plus (PIP) controller is simple to implement and provides a logical extension of conventional proportional-integral and proportional-integral-derivative (PI/PID) controllers, with additional dynamic feedback and input compensators introduced automatically by the NMSS formulation of the problem when the process is of greater than first order or has appreciable pure time delays. The present paper applies the PIP methodology to the ALSTOM benchmark challenge, which takes the form of a highly coupled multi-variable linear model, representing the gasifier system of an integrated gasification combined cycle (IGCC) power plant. In particular, a straightforwardly tuned discrete-time PIP control system based on a reduced-order backward-shift model of the gasifier is found to yield good control of the benchmark, meeting most of the specified performance requirements at three different operating points
The performance of the quantum adiabatic algorithm on random instances of two optimization problems on regular hypergraphs
In this paper we study the performance of the quantum adiabatic algorithm on
random instances of two combinatorial optimization problems, 3-regular 3-XORSAT
and 3-regular Max-Cut. The cost functions associated with these two
clause-based optimization problems are similar as they are both defined on
3-regular hypergraphs. For 3-regular 3-XORSAT the clauses contain three
variables and for 3-regular Max-Cut the clauses contain two variables. The
quantum adiabatic algorithms we study for these two problems use interpolating
Hamiltonians which are stoquastic and therefore amenable to sign-problem free
quantum Monte Carlo and quantum cavity methods. Using these techniques we find
that the quantum adiabatic algorithm fails to solve either of these problems
efficiently, although for different reasons.Comment: 20 pages, 15 figure
Imaging Polarimeter Arrays for Near-Millimeter Waves
An integrated-circuit antenna array has been developed that images both polarization and intensity. The array consists of a row of antennas that lean alternately left and right, creating two interlaced sub-arrays that respond to different polarizations. The arrays and the bismuth bolometer detectors are made by a photoresist shadowing technique that requires only one photolithographic mask. The array has measured polarization at a wavelength of 800 µm with an absolute accuracy of 0.8° and a relative precision of 7 arc min. and has demonstrated nearly diffraction-Iimited resolutiort of a 20° step in polarization
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Release of cholesterol-rich particles from the macrophage plasma membrane during movement of filopodia and lamellipodia.
Cultured mouse peritoneal macrophages release large numbers of ~30-nm cholesterol-rich particles. Here, we show that those particles represent fragments of the plasma membrane that are pulled away and left behind during the projection and retraction of filopodia and lamellipodia. Consistent with this finding, the particles are enriched in proteins found in focal adhesions, which attach macrophages to the substrate. The release of particles is abolished by blocking cell movement (either by depolymerizing actin with latrunculin A or by inhibiting myosin II with blebbistatin). Confocal microscopy and NanoSIMS imaging studies revealed that the plasma membrane-derived particles are enriched in 'accessible cholesterol' (a mobile pool of cholesterol detectable with the modified cytolysin ALO-D4) but not in sphingolipid-sequestered cholesterol [a pool detectable with ostreolysin A (OlyA)]. The discovery that macrophages release cholesterol-rich particles during cellular locomotion is likely relevant to cholesterol efflux and could contribute to extracellular cholesterol deposition in atherosclerotic plaques
Planning and assessing to improve campus--community engagement
Two methods for assessing the scholarship of engagement at the institutional level are presented: (a) the Comprehensive Assessment of the Scholarship of Engagement (CASE), a systematic method that compiles information about service learning and community engagement, identifies campus strengths, and prioritizes planning areas, and (b) an institutional portfolio that provides a rich data base of descriptive and evaluative information
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