Nonminimum phase adaptive inverse control for settle performance applications

Single-track hard disk drive (HDD) seek performance is measured by settle time, $t_s$, defined as the time from the arrival of a seek command until the measured position reaches and stays within an acceptable distance from the target track. Our previous work has shown feedforward dynamic inversion, coupled with an aggressive desired trajectory $y_d$, is capable of achieving high performance settle times when the closed-loop dynamics are time-invariant and accurately modeled. In contrast, we describe an adaptive inversion procedure in this paper which removes the requirement for accurate initial models and tracks the position-variant dynamics present in our Servo Track Writer (STW) experimental apparatus. The proposed indirect adaptive inversion algorithm relies on a recursive least squares (RLS) estimate of the closed-loop dynamics. Pre-filtering of the RLS input signals, covariance resetting, and relative NMP system partitioning are necessary additions to the baseline adaptive algorithm in order to achieve fast settle times. Compared to the nonadaptive solution with accurate system identification, we show the adaptive algorithm achieves a 22% reduction in average settle time and a 53% reduction in settle time standard deviation.     

Reactive transport in porous media: a comparison of model prediction with laboratory visualization

Groundwater transport models that accurately describe spreading of nonreactive solutes in an aquifer can poorly predict concentrations of reactive solutes. The dispersive term in the advection-dispersion equation can overpredict pore-scale mixing, and thereby overpredict homogeneous chemical reaction. We quantified this experimentally by imaging instantaneous colorimetric reactions between solutions of aqueous CuSO4 and EDTA4- within a 30-cm long translucent chamber packed with cryolite sand that closely matched the optical index of refraction of water. A charge-coupled device camera was used to quantify concentrations of blue CuEDTA2- within the chamber as it was produced by mixing of the two reactants at different flow rates. We compared these experimental results with a new analytic solution for instantaneous bimolecular reaction coupled with advection and dispersion of the product and reactants. For all flow rates, the concentrations of CuEDTA2- recorded in the experiments were about 20% less than predicted by the analytic solution, thereby demonstrating that models assuming complete mixing at the pore scale can overpredict reaction during transport.     

“Where’s Farah?”: Knowledge silos and information fusion by distributed collaborating teams

The Cognitively-Based Rapid Assessment Methodology (C-RAM) system manages multiple-user interactions as users work with multiple information sources. Further, it allows users to view, exchange, organize, and combine the information available and it facilitates group decision-making. Three-member teams, randomly assigned in either the (a) view others’ whiteboards or (b) cannot view others’ whiteboards conditions, completed an intelligence analysis and mission planning task. Each team member was given access to a virtual whiteboard populated with decision cards (DCards) containing intelligence information constrained to a specific area of expertise. DCards can be assessed (rated) for decision impact and importance and team members have access to all DCards regardless of experimental condition. Team members who can view their teammates’ whiteboards during collaborative activities achieve significantly higher performance. When compared to teams unable to view others’ whiteboards, they move their own DCards less frequently, add fewer additional DCards to their own whiteboards, and rate others’ DCards less frequently. Additionally, rating one’s own DCards is the only process positively related team performance.     

Polyphenol contents of Pu-Erh teas and their abilities to inhibit cholesterol biosynthesis in Hep G2 cell line

Thirty samples of Pu-Erh tea (a microbial fermented Chinese tea) were collected and assayed for cholesterol synthesis inhibitory activity and polyphenol composition. All samples were able to inhibit the cholesterol biosynthesis in Hep G2 cell model and the inhibition ratios ranged from 7% to 35%. The inhibition abilities of tea polyphenol standards were in the order of gallocatechin gallate (GCG) > epigallocatechin gallate (EGCG) > epicatechin gallate (ECG) > gallic acid > epigallocatechin (EGC) > myricetin > quercetin > catechin (C) > epicatechin (EC). It appears that catechins with a galloyl structure on the B ring or a gallic acid moiety in the structure would have better inhibitory activity. In summary, tea polyphenol may play a role on the cholesterol biosynthesis inhibitory ability of Pu-Erh tea.     

Fluidized Bed Granulation with Pvp K90 and Pvp K120

The characteristics and growth mechanisms of fluidized bed granules are dependent both on process variables and the grades of PVP binders used. Generally, an increase in the concentration, spraying rate and volume of binder solution caused an increase in granule size and a decrease in size distribution. These two factors will in turn affect the poured and tapped densities of granules. Granules prepared with PVP K90 solution appeared to grow by primary and secondary agglomeration to give an aggregate structure. Granules prepared with PVP K120 solution were formed through snowballing as the primary agglomeration process. This occurred at low binder solution concentration with secondary agglomeration taking place when the concentration of PVP K120 solution was increased.     

Controlling the Er content of porous silicon using the doping current intensity

The results of an investigation on the Er doping of porous silicon are presented. Electrochemical impedance spectroscopy, optical reflectivity, and spatially resolved energy dispersive spectroscopy (EDS) coupled to scanning electron microscopy measurements were used to investigate on the transient during the first stages of constant current Er doping. Depending on the applied current intensity, the voltage transient displays two very different behaviors, signature of two different chemical processes. The measurements show that, for equal transferred charge and identical porous silicon (PSi) layers, the applied current intensity also influences the final Er content. An interpretative model is proposed in order to describe the two distinct chemical processes. The results can be useful for a better control over the doping process.

PACS

81.05.Rm; 82.45.Rr     

Housing quality and resilience in New Zealand

There is extensive research on the negative health impacts of poor housing quality. However, little is known about the potential health benefits of high-quality housing in poor neighbourhoods. Neighbourhoods with unexpectedly good health outcomes despite high levels of deprivation have been deemed resilient places and housing quality in these areas may be a contributor to this resilience. This study aimed to evaluate whether an indicator of neighbourhood housing quality was associated with a previously quantified resilience index (RINZ) in New Zealand. It was found that areas with high housing quality tended to have higher median income, greater proportions of partnered people and shorter-term residents, and very low proportions of Māori. A positive association was found between housing quality and resilience, after adjustment for deprivation. There was no indication of differences by heterogeneity in housing quality within the aggregate unit of analysis. These findings pose the hypothesis that improving housing quality in similarly deprived areas that have poor health outcomes could potentially boost health. To extend this understanding, further development of a more sophisticated housing quality indicator is recommended.     

Somatotropic axis and concentrate supplementation in grazing dairy cows of genetically diverse origin

Supplementing pasture-fed dairy cows with concentrates in early lactation was hypothesized to result in an earlier postpartum recoupling of the somatotropic axis in New Zealand (NZ)-type Holstein-Friesian dairy cows than in North American (NA)-type cows. To test this hypothesis, NA (n = 30) and NZ (n = 30) cows were allocated to 1 of 3 supplementation strategies (0, 3, or 6 kg of dry matter concentrate/d) for the first 12 wk of lactation in a completely randomized design and a 2 × 3 factorial arrangement. Production traits and characteristics of the somatotropic axis were studied at phenotypic, hormonal, and gene expression levels. Milk production and plasma metabolite concentrations were measured weekly, and liver was biopsied in wk 1, 4, 8, and 12 postcalving. North American cows produced more milk and displayed a larger degree of somatotropic axis uncoupling than did NZ cows. This was evident in strain differences in body condition score, blood growth hormone, and insulin-like growth factor-1 concentrations, and hepatic expression of growth hormone receptor-1a. No strain × diet interactions were observed for any characteristic of the somatotropic axis at either the blood metabolite or gene expression level; however, blood insulin concentrations during wk 7 to 11 postpartum increased with concentrate supplementation in NZ but not NA cows. These results demonstrate that feeding supplements does not result in an earlier recoupling of the somatotropic axis; however, the greater blood insulin concentrations with concentrate feeding in NZ cows from wk 7 may result in an earlier recoupling in this genetic strain, after the period investigated in this study. Further research is required to understand differences in insulin control between these genetic strains.     

Training issues.

This interesting set of articles, taken as a group, suggests that we have come a long way toward the integration of family therapy into the training of psychologists. The question is no longer "Should psychologists be trained in family therapy?" but "How can such training best be accomplished, in what settings, with what approaches, and how related to other elements of the graduate or postdoctoral program?" The articles by Ribordy (see record 1989-13401-001) and by Lebow (see record 1989-13365-001) address the central issues in training from different vantages (the family institute versus the academic program) but converge on many points. I will comment mainly on these two articles, but first I want to take note of some of the ideas raised by Berger and Jurkovic (see record 1989-12730-001). They describe and persuasively illustrate a contextual approach to family work that emphasizes the varying settings in which therapy may occur. Thus they are concerned with a "supersystem" that incorporates these extra therapeutic systems as well as clinicians and family. It will be no great surprise to the readers of this Journal that many of these same points emerge from Ribordy's and Lebow's more general discussions of training issues. They explore the separate territories of the academic graduate program and the family institute as settings for training and ably outline the advantages and disadvantages of each. (PsycINFO Database Record (c) 2010 APA, all rights reserved)