7,165 research outputs found
An improved single-step lysis protocol to measure luciferase bioluminescence in Plasmodium falciparum
No full textThis report describes the optimization and evaluation of a simple single-step lysis protocol to measure luciferase bioluminescence from genetically modified Plasmodium falciparum. This protocol utilizes a modified commercial buffer to improve speed of assay and consistency in the bioluminescence signal measured by reducing the manipulation steps required to release the cytoplasmic fraction. The utility of this improved assay protocol is demonstrated in typical assays that explore absolute and temporal gene expression activity
Automation of Homologation
No full textWe are developing content and software to automate the homologation for our Electronics courses to deal with the increasing diversity in knowledge and skills of the master students who have completed their bachelor’s at other universities. The courses’ content has been structured such that dependencies between topics become explicit. A parameterized database was created with questions characterized with, e.g., subject, Bloom level, and many other tags. It enables the generation of questions and personalized quizzes for individual students at any time. This allows teachers and students to gain insight into the student’s level of knowledge and skills and provide adequate feedback at any time. The questions and complete quizzes can also be exported to learning platforms like Brightspace.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic
Asymptotic convergence analysis and influence of initial guesses on composite Anderson acceleration
No full textAlthough Anderson acceleration AA(m) has been widely used to speed up nonlinear solvers, most authors are simply using and studying the stationary version of Anderson acceleration. The behavior and full potential of the non-stationary version of Anderson acceleration methods remain an open question. Motivated by the hybrid linear solver GMRESR (GMRES Recursive), we recently proposed a set of non-stationary Anderson acceleration algorithms with dynamic window sizes AA(m,AA(n)) for solving both linear and nonlinear problems. Significant gains are observed for our proposed algorithms but these gains are not well understood. In the present work, we first consider the case of using AA(m,AA(1)) for accelerating linear fixed-point iteration and derive the polynomial residual update formulas for non-stationary AA(m,AA(1)). Like stationary AA(m), we find that AA(m,AA(1)) with general initial guesses is also a multi-Krylov method and possesses a memory effect. However, AA(m,AA(1)) has higher order degree of polynomials and a stronger memory effect than that of AA(m) at the k-th iteration, which might explain the better performance of AA(m,AA(1)) compared to AA(m) as observed in our numerical experiments. Moreover, we further study the influence of initial guess on the asymptotic convergence factor of AA(1, AA(1)). We show a scaling invariance property of the initial guess x for the AA(1,AA(1)) method in the linear case. Then, we study the root-linear asymptotic convergence factor under scaling of the initial guess and we explicitly indicate the dependence of root-linear asymptotic convergence factors on the initial guess. Lastly, we numerically examine the influence of the initial guess on the asymptotic convergence factor of AA(m) and AA(m,AA(n)) for both linear and nonlinear problems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public
Composite Anderson acceleration method with two window sizes and optimized damping
No full textIn this article, we propose and analyze a set of fully nonstationary Anderson acceleration (AA) algorithms with two window sizes and optimized damping. Although AA has been used for decades to speed up nonlinear solvers in many applications, most authors are simply using and analyzing the stationary version of AA (sAA) with fixed window size and a constant damping factor. The behavior and potential of the nonstationary version of AA methods remain an open question. Most efficient linear solvers however use composable algorithmic components. Similar ideas can be used for AA to solve nonlinear systems. Thus in the present work, to develop nonstationary AA algorithms, we first propose a systematic way to dynamically alternate the window size (Formula presented.) by the multiplicative composite combination, which means we apply sAA((Formula presented.)) in the outer loop and apply sAA((Formula presented.)) in the inner loop. By doing this, significant gains can be achieved. Second, to make AA to be a fully nonstationary algorithm, we need to combine these strategies with our recent work on the nonstationary AA algorithm with optimized damping (AAoptD), which is another important direction of producing nonstationary AA and nice performance gains have been observed. Moreover, we also investigate the rate of convergence of these nonstationary AA methods under suitable assumptions. Finally, our numerical results show that some of these proposed nonstationary AA algorithms converge faster than the stationary sAA method and they may significantly reduce the storage and time to find the solution in many cases.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Numerical Analysi
Warm Hydromechanical Deep Drawing of AA 5754-O and Optimization of Process Parameters
No full textAbstract
Warm hydromechanical deep drawing (WHDD) has increasingly been implemented by automotive industry due to its various benefits including mass reduction opportunities in auto body-in-white components and improved formability for lightweight alloys. In the first part of the current study, WHDD of AA 5754-O was studied. In order to obtain the highest formability, an optimization study was performed for AA 5754-O WHDD process parameters (tool temperature, hydraulic pressure (HP), and blank holder force (BHF) loading profiles) through finite element analysis (FEA) + experimentation approach. Results showed that the optimal temperature for punch is 25 °C and 300 °C for die and blank holder. In addition, HP was found to be more effective on formability when compared to BHF. Both fast increasing HP and blank holder loading profiles contributes to higher formability.</jats:p
Improving Confidence in the Estimation of Values and Norms
No full textAutonomous agents (AA) will increasingly be interacting with us in our daily lives. While we want the benefits attached to AAs, it is essential that their behavior is aligned with our values and norms. Hence, an AA will need to estimate the values and norms of the humans it interacts with, which is not a straightforward task when solely observing an agent's behavior. This paper analyses to what extent an AA is able to estimate the values and norms of a simulated human agent (SHA) based on its actions in the ultimatum game. We present two methods to reduce ambiguity in profiling the SHAs: one based on search space exploration and another based on counterfactual analysis. We found that both methods are able to increase the confidence in estimating human values and norms, but differ in their applicability, the latter being more efficient when the number of interactions with the agent is to be minimized. These insights are useful to improve the alignment of AAs with human values and norms.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Interactive IntelligenceInformation and Communication TechnologyEthics & Philosophy of Technolog
COMMERCIAL 584\AA PHOTOELECTRON SPECTROMETER
No full textAuthor Institution: Perkin-Elmer LimitedThe design of a commercial 584\AA Photcelectron Spectrometer will be discussed together with some recent research problems investigated by this technique
Open Access to Peer-Reviewed Research through Author/Institution Self-Archiving: Maximizing Research Impact by Maximizing Online Access
No full textAll refereed journals will soon be available online; most of them already are. This means that anyone will be able to access them from any networked desk-top. The literature will all be interconnected by citation, author, and keyword/subject links, allowing for unheard-of power and ease of access and navigability. Successive drafts of pre-refereeing preprints will be linked to the official refereed draft, as well as to any subsequent corrections, revisions, updates, comments, responses, and underlying empirical databases, all enhancing the self-correctiveness, interactivity and productivity of scholarly and scientific research and communication in remarkable new ways. New scientometric indicators of digital impact are also emerging <http://opcit.eprints.org> to chart the online course of knowledge. But there is still one last frontier to cross before science reaches the optimal and the inevitable: Just as there is no longer any need for research or researchers to be constrained by the access-blocking restrictions of paper distribution, there is no longer any need to be constrained by the impact-blocking financial fire-walls of Subscription/Site-License/Pay-Per-View (S/L/P) tolls for this give-away literature. Its author/researchers have always donated their research reports for free (and its referee/researchers have refereed for free), with the sole goal of maximizing their impact on subsequent research (by accessing the eyes and minds of fellow-researchers, present and future) and hence on society. Generic (OAi-compliant) software is now available free so that institutions can immediately create Eprint Archives in which their authors can self-archive all their refereed papers for free for all forever <http://www.eprints.org/>. These interoperable Open Archives <http://www.openarchives.org> will then be harvested into global, jointly searchable "virtual archives" (e.g., <http://arc.cs.odu.edu/>). "Scholarly Skywriting" in this PostGutenberg Galaxy will be dramatically (and measurably) more interactive and productive, spawning its own new digital metrics of productivity and impact, allowing for an online "embryology of knowledge.
Author attribution using profile classifiers
No full textA atribuição autoral (AA) busca identificar um autor de texto a partir de um conjunto de autores conhecidos. Autores deixam rastros em seus textos e é possível identificar características sociolinguísticas baseadas no estilos de escrita refletidos no texto destes autores. A atribuição autoral está cada vez mais demonstrando importância para diversas atividades sociais, em especial para a análise forense. Os trabalhos envolvendo AA demonstram resultados modestos e motivam a exploração de diferentes técnicas para melhorar a acurácia dos modelos atuais. A partir desses pontos, o presente trabalho apresenta uma proposta de pesquisa em nível de mestrado no campo de processamento de língua natural (PLN), com ênfase em AA, com o objetivo geral de melhorar o desempenho de classificadores de atribuição autoral utilizando técnicas de caracterização autoral (CA)Author attribution (AA) seeks to identify a text author from a set of known authors. Authors leave traces in their texts and it is possible to identify sociolinguistic characteristics based on the writing styles reflected in the text of these authors. Author attribution is increasingly showing importance for various social activities, especially forensic analysis. Studies involving AA show modest results and motivate the exploration of different techniques to improve the accuracy of current models. From these perspective, this project presents a master\'s level research proposal in the field of natural language processing (NLP), with an emphasis in AA, with the general objective of improving the performance of AA classifiers using author profiling technique
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Observations of the 57Fe+23 hyperfine transition in clusters of galaxies
No full textWe present a search for the hyperfine transition of the 57Fe+23 ion at 3.071 mm in clusters of galaxies with the ATNF Mopra telescope. The results are compared with a realistic estimate of the peak brightness temperature of the line in a cooling flow cluster A85, using the available X-ray data
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