102 research outputs found
Sequential convex relaxation for convex optimization with bilinear matrix equalities
No full textWe consider the use of the nuclear norm operator, and its tendency to produce low rank results, to provide a convex relaxation of Bilinear Matrix Inequalities (BMIs). The BMI is first written as a Linear Matrix Inequality (LMI) subject to a bi-affine equality constraint and subsequently rewritten into an LMI subject to a rank constraint on a matrix affine in the decision variables. The convex nuclear norm operator is used to relax this rank constraint. We provide an algorithm that iteratively improves on the sum of the objective function and the norm of the equality constraint violation. The algorithm is demonstrated on a controller synthesis example.Accepted Author ManuscriptTeam Raf Van de Pla
Sourcing Stone and Ochre Artifacts: A Review of Why It Matters in Australia (and Beyond)
No full textSourcing transported stone and ochre artifacts to their geological origin is popular in archaeology (Andrefsky 2009; Shackley 1998b, 2008, 2011) and a fundamental starting point for understanding the economic and social processes associated with any stone-based technology (Hiscock and Mitchell 1993). Sourcing research has been applied extensively throughout the world: for example, in Africa (e.g., Bernatchez 2008; Nash et al. 2013, 2016; Negash et al. 2006; Shackley and Sahle 2017; Zipkin et al. 2017), Europe (e.g., Andreeva et al. 2014; Brandl et al. 2014; Cavallo et al. 2017; Sánchez de la Torre, Le Bourdonnec, Gratuze et al. 2017; Moreau et al. 2016), South America (e.g., Barberena et al. 2019; Cackler et al. 1999; Cortegoso et al. 2016; Flegenheimer et al. 2003; Méndez et al. 2018; Pintar et al. 2016; Popelka-Filcoff, Lenehan et al. 2007), Oceania (e.g., Allen and Johnson 1997; Clark et al. 2014; Collerson and Weisler 2007; Kirch et al. 2012; McAlister and Allen 2017; Mills et al. 2010; Weisler et al. 2016), North America (e.g., Boulanger et al. 2015; Church 2000; Eiselt et al. 2011; Gauthier et al. 2012; MacDonald et al. 2011; MacDonald et al. 2018; Pitblado, Boeka Cannon, Neff et al. 2013; Popelka-Filcoff, Robertson et al. 2007; ten Bruggencate et al. 2015), and Asia (e.g., Doelman et al. 2008; Doelman et al. 2012; Frahm 2012b; Frahm et al. 2014; Guo et al. 2005; Jia et al. 2010; Kuzmin and Glascock 2007). Such sourcing work should be, and often is, preceded by comprehensive geoarchaeological survey to establish the availability and distribution of both primary (outcropping) and secondary (waterborne) sources (e.g., Borrazzo 2012; Gazzan et al. 2019; MacDonald et al. 2013; Wilson 2007). In this chapter, we explore the application of sourcing techniques to stone and ochre artifacts in Australia.Full Tex
The Personation of John Suckling, 1635
No full textThe letters of Anthony Mingay indicate that in early 1635 Sir John Suckling was satirically personated in an unnamed play. This article considers Richard Brome’s The Sparagus Garden and James Shirley’s The Lady of Pleasure as possible candidates to be this play. It concludes, however, that the cowardly braggart soldier Sucket in Henry Glapthorne’s The Lady Mother is the most likely personation of Suckling, as the humiliating beating of that character most closely aligns with the attack on Suckling by Sir John Digby as described in Mingay’s letters
Hepatic Gene Expression Profiling to Predict Future Lactation Performance in Dairy Cattle
No full textAn experiment was conducted to obtain a hepatic gene expression dataset from postpubertal dairy heifers that could be fit to a computational model capable of predicting future lactation performance values. The initial animal experiment was conducted to characterize the hepatic transcriptional response to 24-hour total feed withdrawal in one-hundred and two postpubertal Holstein dairy heifers using an 8329-gene oligonucleotide microarray in a randomized block design. Plasma concentration of non-esterified fatty acids was significantly higher, while levels of beta-hydroxybutyrate, triacylglycerol, and glucose were significantly lower with the 24-hour total feed withdrawal. In total, 505 differentially expressed genes were identified and microarray results were confirmed by real-time PCR. Upregulation of key gluconeogenic genes occurred despite diminished dietary substrate and lower hepatic glucose synthesis. Downregulation of ketogenic genes was contrary to the non-ruminant response to feed withdrawal, but was consistent with a lower ruminal supply of short-chain fatty acids as precursors. Following the microarray experiment, the first series of regression analyses was employed to identify relationships between gene expression signal and lactation performance measurements taken over the first lactation of 81 of the subjects from the original study. Regression models were evaluated using mean square prediction error (MSPE) and concordance correlation coefficient (CCC) analysis. The strongest validated stepwise regression models were constructed for milk protein percentage (r = 0.04) and lactation persistency (r = 0.09). To determine if another type of regression analysis would better predict lactation performance, partial least squares (PLS) regression analysis was then applied. Selection of gene expression data was based on an assessment of the linear dependence of all genes in normalized datasets for 81 subjects against 18 dairy herd index (DHI) variables using Pearson correlation analysis. Results were distributed into two lists based on correlation coefficient. Each gene expression dataset was used to construct PLS models for the purpose of predicting lactation performance. The strongest predictive models were generated for protein percentage (r = 0.46), 305-d milk yield (r = 0.44), and 305-d protein yield (r = 0.47). These results demonstrate the suitability of using hepatic gene expression in young animals to quantitatively predict future lactation performance.Ontario Centre for Agricultural GenomicsNatural Sciences and Engineering Research Council of CanadaOntario Ministry of Agriculture, Food and Rural Affair
Verslag fabrieksschema: Adipinezuur
No full textDocument(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science
De verwijdering van zwavel en stikstof uit minerale oliën door katalytisch hydrogeneren
No full textApplied Science
Rank-based optimization techniques for estimation problems in optics
No full textAberrations in optical systems, such as telescopes and microscopes, degrade the quality of the images that can be produced by these systems. For example, an object that is positioned out of focus produces a blurred image on a camera sensor and the turbulent air in the earth’s atmosphere reduces the imaging performance of telescopes. In this thesis we only consider wavefront aberrations. AO can be used to compensate for these wavefront aberrations. The working principle of AO is to quantify by measuring or estimation the wavefront aberration and to dynamically adjust wavefront modulating devices, such as Deformable Mirrors (DMs), to counteract the aberration and thereby improving the optical performance. The estimation of the wavefront aberration based on images of a point source is called phase retrieval, which is a highly nonlinear estimation problem. The success of the estimation usually depends on the (type of) algorithm, the available information on the aberration that is incorporated in the estimate, and the degree to which the model of the optical system corresponds to reality. In this thesis we propose a convex optimization-based method for phase retrieval. The method allows for easy inclusion of many types of prior information on the aberration. Furthermore, we develop an efficient implementation of the optimization. The robustness of the approach against measurement noise is investigated and compared with several other state of the art algorithms. Experimental validation shows the algorithmis well able to estimate aberrations in real-life circumstances. A new type of prior information is introduced to estimate dynamic wavefront aberrations. In literature and in practice, the optical path is split between either a wavefront sensor and a camera, or between multiple cameras in order to reliable estimate an aberration. The inherent problem is that between the sensor and cameras the aberration can differ (Non-Common Path (NCP) errors), and a wrong estimate is used in the compensation by the AO system. We propose a method to estimate the aberration from measurements by a single camera, by assuming that the aberration evolves according to (non-specific) model, i.e. the dynamics are contained in a model-set. At the same time that we estimate the aberration, we also identify the dynamics according to which the aberration evolves over time. The estimation of the wavefront aberration based on images of an unknown object is called blind deconvolution if both the aberration and object are estimated. Like phase retrieval, this too is a highly nonlinear estimation problem. We propose the first convexoptimization based estimation method for blind deconvolution problems that estimate aberration and object when the images are acquired using coherent illumination. The method allows for the inclusion of many existing types of prior information on the object and/or aberration. Finally, we analyze controllers for segmented mirrors in large ground-based telescopes. These mirrors consist of many interconnected hexagonal segments. This distributed nature of the system warrants the investigation into whether the controller that keeps the segments aligned can be designed in such a way that it can be distributed over the segments as well, essentially resulting in a distributed controller where local controllers communicate with each other. What complicates the analysis is that the dynamics across segments are not necessarily decoupled: the wind load can be correlated and the flexibility in the supporting structure of the segments can cause dynamic coupling. We investigate the design of a distributed controller that incorporates these global dynamics. Furthermore, we investigate the performance of the distributed controller and howit relates to the communication and interconnection pattern of the local controllers.Team Raf Van de Pla
Convex optimization-based blind deconvolution for images taken with coherent illumination
No full textA rank-constrained reformulation of the blind deconvolution problem on images taken with coherent illumination is proposed. Since in the reformulation the rank constraint is imposed on a matrix that is affine in the decision variables, we propose a novel convex heuristic for the blind deconvolution problem. The proposed heuristic allows for easy incorporation of prior information on the decision variables and the use of the phase diversity concept. The convex optimization problem can be iteratively re-parameterized to obtain better estimates. The proposed methods are demonstrated on numerically illustrative examples.Team Raf Van de Pla
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