A moving horizon approach to Networked Control system design

This paper presents a control system design strategy for multivariable plants where the controller, sensors and actuators are connected via a digital, data-rate limited, communications channel. In order to minimize bandwidth utilization, a communication constraint is imposed which restricts all transmitted data to belong to a finite set and only permits one plant to be addressed at a time. We emphasize implementation issues and employ moving horizon techniques to deal with both control and measurement quantization issues. We illustrate the methodology by simulations and a laboratory-based pilot-scale study.     

Concordant but different: Cognitive function, cerebral anatomy, and metabolism in monozygotic twins with Alzheimer's disease.

To illustrate the utility of the twin method in Alzheimer's disease (AD) research, a pair of monozygotic twins, concordant for the disease but markedly different in their clinical presentations, was studied in detail. Neuropsychological evaluation, magnetic resonance imaging (MRI), and cerebral glucose metabolic studies revealed a typical behavioral presentation for AD in Twin A. In contrast, Twin B showed prominent visuospatial impairments. Although there was no identified cause for the disparate presentations, a close correspondence was observed between the neuropsychological findings and the regional brain measures. The results suggest that the trajectory of AD may vary widely even in genetically identical individuals. Factors accounting for the variability include potential intrauterine, early developmental, and environmental differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Small blaze angle gratings with various surface treatments for use in the extreme ultraviolet

Three replica gratings were made from a single master; two were epoxy overcoated with different thicknesses of gold, and one was replicated directly in gold. Their performance in EUV light at grazing incidence angles was measured and compared.     

Optimization of decision rules for hydroelectric operation to reduce both eel mortality and unnecessary turbine shutdown: A search for a win–win solution

Worldwide populations of freshwater eels have declined with one of the contributing causes related to mortality during passage through hydropower turbines. An inherent trade‐off underlies turbine management where the competing demand for more hydropower comes at the expense of eel survival. A win–win solution exists when an option performs better on all competing demands compared to other options. A predictive model for eel migration based on a recent telemetry study was used to develop decision rules for turbine management in the Shenandoah River system. The performance of alternative decision rules was compared to the status quo policy to search for win–win solutions. Decision rules were defined by the probability of eel movement and were evaluated by the probabilities of false positive and false negative errors. The exact value of the cut‐off probability used in the decision rule will need to be determined through negotiation between stakeholders, but a range of cut‐off probabilities resulted in a win–win situation with both reduced eel mortality and increased turbine operation relative to the current shutdown strategy. Monitoring the implementation is needed to evaluate and update the predictive model and to refine the decision rule. Although the decision is framed for the Shenandoah River system, the analytical approach could be used to develop decision rules for turbine shutdown policy in other areas.     

Experimental habitat scenting inhibits colonization by beaver,Castor canadensis

Unoccupied beaver (Castor canadensis) sites in New York State were for two years experimentally scented with a mixture of beaver castoreum and anal gland secretion. These sites were colonized less often than unscented control sites. The beaver is the first mammal to have been shown experimentally to use intraspecific odor cues when settling in vacant habitat. Territorial pheromones may be useful as repellents for beaver or other rodents.     

Signal-to-noise ratio for astronomical imaging by deconvolution from wave-front sensing

One method for improving the quality of astronomical images measured through a atmospheric turbulence uses simultaneous short-exposure measurements of both an image and the output of a wave-front sensor exposed to an image of the telescope pupil. The wave-front sensor measurements are used to reconstruct an estimate of the instantaneous generalized pupil function of the telescope, which is used to compute an estimate of the instantaneous optical transfer function, which is then used in a deconvolution procedure. This imaging method has been called both deconvolution from wave-front sensor (DWFS) measurements and self-referenced speckle holography. We analyze the signal-to-noise ratio (SNR) behavior of this imaging method in the spatial frequency domain. The analysis includes effects arising from differences in the correlation properties of the incident and the estimated pupil phases and the fact that the object-spectrum estimator is a randomly filtered doubly stochastic Poisson random process. SNR resultsobtained for the DWFS method are compared with the speckle-imaging powerspectrum SNR for equivalent seeing conditions and light levels. It is shown that for unresolved stars the power-spectrum SNR is superior to the DWFS SNR. However, for extended objects the power-spectrum SNR and the DWFS SNR are similar. Since speckle imaging uses a separate Fourier phasereconstruction process not required by the DWFS method, the DWFS method provides an alternative to speckle imaging that uses simple postprocessing at the cost of a wave-front sensor measurement but with no loss of SNR performance for extended objects.     

Remote sensing of atmospheric turbulence and transverse winds from wave-front slope measurements from crossed optical paths

In the theory of atmospheric turbulence, the strength of the spatial variations of the index of refraction n is proportional to a parameter known as the atmospheric-structure constant. The atmosphericstructure constant is denoted C(2)(n)(z) and is a function of position along the optical path z. The characteristics of the temporal variations of the index of refraction are related to both C(2)(n)(z) and to the transverse wind velocity V(z). Current optical techniques for remotely sensing C(2)(n)(z) and V(z) rely primarily on the spatial or temporal cross-correlation properties of the intensity of the optical field. In the remote-sensing technique proposed here, we exploit the correlation properties of the wave-front slope measured from two point sources to obtain profiles of C(2)(n)(z) and V(z). The two sources are arranged to give crossed optical paths. The geometry of the crossed paths and the characteristics of the wave-front slope sensor determine the achievable resolution. The signal-to-noise ratio calculationsindicate the need for multiple measurements to obtain useful estimates of the desired quantities.     

Halogenated ligands and their interactions with amino acids: implications for structure-activity and structure-toxicity relationships

The properties of chemicals are rooted in their molecular structure. It follows that structural analysis of specific interactions between ligands and biomolecules at the molecular level is invaluable for defining structure-activity relationships (SARs) and structure-toxicity relationships (STRs). This study has elucidated the structural and molecular basis of interactions of biomolecules with alkyl and aryl halides that are extensively used as components in many commercial pesticides, disinfectants, and drugs. We analyzed the protein structures deposited in Protein Data Bank (PDB) for structural information associated with interactions between halogenated ligands and proteins. This analysis revealed distinct patterns with respect to the nature and structural characteristics of halogen interactions with specific types of atoms and groups in proteins. Fluorine had the highest propensity of interactions for glycine, while chlorine for leucine, bromine for arginine, and iodine for lysine. Chlorine, bromine and iodine had the lowest propensity of interactions for cysteine, while fluorine had a lowest propensity for proline. These trends for highest propensity shifted towards the hydrophobic residues for all the halogens when only interactions with the side chain were considered. Halogens had equal propensities of interaction for the halogen bonding partners (nitrogen and oxygen atoms), albeit with different geometries. The optimal angle for interactions with halogens was approximately 120 degrees for oxygen atoms, and approximately 96 degrees for nitrogen atoms. The distance distributions of halogens with various amino acids were mostly bimodal, and the angle distributions were unimodal. Insights gained from this study have implications for the rational design of safer drugs and commercially important chemicals.     

Necessary and sufficient convergence conditions of the instrumental variable method for identification

The consistency of the instrumental variable method is considered for a system driven by independent identically distributed input signals with zero mean. Necessary and sufficient conditions for convergence are developed with respect to the given model structure. The sufficient and necessary conditions are established for cases with and without data prefiltering. In this paper we extend on existing results such that the requirements on the degree of the instrumental variables can be relaxed. Numerical examples supporting the theoretical results are provided.     

Additively patterned ferroelectric thin films with vertical sidewalls

The functional properties of electroceramic thin films can be degraded by subtractive patterning techniques used for microelectromechanical (MEMS) applications. This work explores an alternative deposition technique, where lead zirconate titanate (PZT) liquid precursors are printed onto substrates in a desired geometry from stamp wells (rather than stamp protrusions). Printing from wells significantly increased sidewall angles (from ~1 to >35 degrees) relative to printing solutions from stamp protrusions. Arrays of PZT features were printed, characterized, and compared to continuous PZT thin films of similar thickness. Three‐hundred‐nanometer‐thick printed PZT features exhibit a permittivity of 730 and a loss tangent of 0.022. The features showed remanent polarizations of 26 μC/cm², and coercive fields of 95 kV/cm. The piezoelectric response of the features produced an e_31,f of ?5.2 C/m². This technique was also used to print directly atop prepatterned substrates. Optimization of printing parameters yielded patterned films with 90° sidewalls. Lateral feature sizes ranged from hundreds of micrometers down to one micrometer. In addition, several device designs were prepatterned onto silicon on insulator (SOI) wafers (Si/SiO₂/Si with thicknesses of 0.35/1/500 μm). The top patterned silicon was released from the underlying material, and PZT was directly printed and crystallized on the free‐standing structures.