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132 results on '"Thompson, David F."'

4. Reduced-risk fungicides help manage brown rot and other fungal diseases of stone fruit

Author

Adaskaveg, James E., Förster, Helga, Gubler, W. Doug, Teviotdale, Beth L., and Thompson, David F.

Subjects
Pest Management, fungicide, stone fruit, reduced risk, brown rot, gray mold, Rhizopus rot, postharvest, packing line, preharvest, disease management
Abstract

New reduced-risk fungicides are highly effective in managing both pre- and postharvest diseases of stone fruit crops in California, and they have replaced most previously registered materials. These fungicides have a low impact on the environment, high specificity to target organisms, and low potential for groundwater contamination and human health risks. In stone fruit, they can be successfully used to manage brown rot blossom blight in a new delayed-bloom fungicide application program for low-precipitation years. In our studies, we found that fungicide treatments applied 1 to 14 days before harvest were also effective against preharvest brown rot and protected fruit from fungal decays initiated during harvest. Practices such as mixtures and rotations can be implemented to prevent resistance from developing and to ensure the lasting efficacy of these reduced-risk fungicides.

Published
2005

10. A simplified robust circle criterion using the sensitivity-based quantitative feedback theory formulation

Author

Thompson, David F.

Subjects
Differential equations -- Asymptotic theory, Differential equations, Nonlinear -- Research, Feedback control systems -- Research, Engineering and manufacturing industries, Science and technology
Abstract

The circle criterion provides a sufficient condition for global asymptotic stability for a specific class of nonlinear systems, those consisting of the feedback interconnection of a single-input, single-output linear dynamic system and a static, sector-bounded nonlinearity. Previous authors (Wang et al., 1990) have noted the similarity between the graphical circle criterion and design bounds in the complex plane stemming from the Quantitative Feedback Theory (QFT) design methodology. The QFT formulation has specific advantages from the standpoint of controller synthesis. However, the aforementioned approach requires that plant uncertainty sets (i.e., 'templates') be manipulated in the complex plane. Recently, a modified formulation for the QFT linear robust performance and robust stability problem has been put forward in terms of sensitivity function bounds. This formulation admits a parametric inequality which is quadratic in the open loop transfer function magnitude, resulting in a computational simplification over the template-based approach. In addition, the methodology admits mixed parametric and nonparametric plant models. The disk inequality which results represents a much closer analog of the circle criterion, requiring only scaling and a real axis shift. This observation is developed in this paper, and the methodology is demonstrated in this paper via feedback design and parametric analysis of a quarter-car active suspension model with a sector nonlinearity.

Published
1999

11. The metabolic fate and effects of 2-Bromophenol in male Sprague–Dawley rats

Author

Adesina-Georgiadis, Kyrillos N., Gray, Nicola, Plumb, Robert S., Thompson, David F., Holmes, Elaine, Nicholson, Jeremy K., and Wilson, Ian D.

Abstract

1. The metabolic fate and urinary excretion of 2-bromophenol, a phenolic metabolite of bromobenzene, was investigated in male Sprague–Dawley rats following single intraperitoneal doses at either 0, 100, or 200 mg/kg. 2. Urine was collected for seven days and samples analysed using 1 H NMR spectroscopy, inductively coupled plasma (ICP)MS, and UPLC-MS. 3. 1 H NMR spectroscopy of the urine samples showed that, at these doses, 2-bromophenol had little effect on endogenous metabolite profiles, supporting histopathology and clinical chemistry data, which showed no changes associated with the administration of 2-bromophenol in this study. 4. The use of ICP-MS provided a means for the selective detection and quantification of bromine-containing species and showed that between 15 and 30% of the dose was excreted via the urine over 7 days of the study for both the 100 and 200 mg doses, respectively. 5. The bulk of the excretion of Br-containing material had occurred by 8 h post administration. UPLC-MS of urine revealed a number of metabolites of 2-bromophenol, with 2-bromophenol glucuronide and 2-bromophenol sulphate identified as the major species. A number of minor hydroxylated metabolites were also detected as their glucuronide, sulphate, or O-methyl conjugates. There was no evidence for the production of reactive metabolites.

Published
2019
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12. Gain-bandwidth optimal design for the new formulation quantitative feedback theory

Author

Thompson, David F.

Subjects
Feedback control systems -- Research, Engineering and manufacturing industries, Science and technology
Abstract

Recent work in Quantitative Feedback Theory (QFT) has extended the methodology to include a more mathematically tractable formulation which allows consideration of both parametric and non-parametric uncertainty. An issue that remains largely unsolved is that of constructive existence conditions for optimal QFT controllers. The methodology developed in Thompson and Nwokah (1994) was to build upon the classical Bode analysis approach to loop shaping by defining the structure and parameters of an acceptable initial QFT controller a priori; locally optimal controllers of this structure could then be computed via a constrained nonlinear programming algorithm. The primary purpose of this paper is to extend this methodology to the sensitivity-based, 'new formulation' QFT bounds. This technique is demonstrated for the nonminimum-phase problem of Nordgren et al. (1994).

Published
1998

33. Green flexo converter can create competitive edge

Author

Thompson, David F.

Subjects
Flexography -- Environmental aspects, Green products -- Production management, Packaging industry -- Environmental aspects, Business, Chemicals, plastics and rubber industries, Forest products industry
Abstract

Environmental commitment by flexographic packagers and printers doesn't have to come at the expense of quality, cost, functionality and productivity. The fifth in our series reviews developments in technologies and [...]

Published
1994

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