323,080 research outputs found
Syntax and semantics: Similarities in late positive components
No full textThe ERP component known as the (syntactic) P600 has long been associated with syntactic processing as it has consistently been seen to have a larger amplitude to critical words in sentences that contain syntactic violations or complex structure. With the later discovery of a morphologically similar component that was sensitive to violations that were more semantic in nature (semantic P600), P600 theories moved to encompass these findings into theoretical frameworks that explained how the same component could be seen in these two different instances. This is despite the fact that there has been no empirical investigation into whether or not these two positivities are in fact reflecting the same kind of underlying processing. This thesis aims to do this investigative work, using central and lateralised ERP paradigms and investigating individual differences such as familial sinistrality and aging to assess whether or not these two components are consistently elicited under the same conditions.
Experiment 1 looked at sentences containing violations known to elicit the syntactic P600 or the semantic P600. The results showed that participants differed in their responses to the syntactic P600 sentences dependent on familial sinistrality profile (whether or not the individual had left handed relatives) but did not differ in response to the semantic P600 sentences. Experiment 2 followed up on these initial differences using a lateralised version of Experiment 1, biasing processing to each hemisphere individually in order to assess lateralisation patterns. The results showed that participants of differing familial sinistrality profiles differed in terms of their hemispheric contributions to processing these sentences. While those with no history of familial sinistrality had a lateralised response to the syntactic P600 sentences, the group which did have a history of familial sinistrality showed a bilateral pattern, as did both groups in response to the semantic P600 sentences. This difference in eliciting conditions again indicates that the two types of P600 responses may not be the same. Experiment 3 examined the processing of the sentences in an older adult sample. Distributional changes in the form of a frontal shift have previously been seen for the syntactic P600 in older adults, and this same pattern was found again here. However, the same shift was not seen for the semantic P600 sentences, adding further evidence to the proposal that the semantic and syntactic variants of the P600 are not reflecting the same type of processing.
Taken together, the experiments in the thesis cast doubt on the multitude of theories that assume both syntactic and semantic variants of the P600 to be the same and argue that domain is an imperfect basis on which to categorise morphologically similar components.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-08-01The student, Michelle Leckey, accepted the attached license on 2019-06-12 at 07:05.The student, Michelle Leckey, submitted this Dissertation for approval on 2019-06-12 at 07:10.This Dissertation was approved for publication on 2019-06-12 at 13:40.DSpace SAF Submission Ingestion Package generated from Vireo submission #14030 on 2019-11-26 at 13:03:25Made available in DSpace on 2019-11-26T20:49:10Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-06-12Embargo set by: Seth Robbins for item 112899
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Sparse wavenumber recovery and prediction of anisotropic guided waves in composites: A comparative study
No full textGuided wave methodologies are among the established approaches for structural health monitoring (SHM). For guided wave data, being able to accurately estimate wave properties in the absence of ample measurements can greatly facilitate the often time-consuming and potentially expensive data acquisition procedure. Nevertheless, inherent complexities of the guided waves, including their multimodal and frequency dispersive nature, hinder processing, analysis, and behavior prediction. The severity of these complexities is even higher in anisotropic media, such as composites. Several methods, including sparse wavenumber analysis (SWA), have been proposed in the literature to characterize guided wave propagation by extracting wave characteristics in a particular medium from the information contained in a few measurements, and subsequently using this information for full wavefield prediction. In this paper, we investigate the efficacy of guided wave reconstruction techniques, based on SWA, for predicting the behavior of guided waves in composite materials. We implement these techniques on several experimental and simulation data sets. We study their performance in estimating the frequency-dependent (dispersive) and anisotropic velocities of guided waves and in reconstructing full wavefields from limited available information
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Multi-site delamination detection and quantification in composites through guided wave based global-local sensing
No full textAdvanced composite materials are contributing to a revolution in aerospace applications. Rapid inspection techniques for detecting and quantifying damage in large composites are critical for ensuring operability and safety of composite structures. Moreover, in the development and manufacturing of next-generation composite materials, rapid inspection techniques are imperative for evaluating and certifying the materials.
This paper presents a guided wave based global-local sensing method for rapid detection and quantification of delamination damage in large composite panels. The global-local approach uses a hybrid system consisting of a piezoelectric transducer (PZT) for generating guided waves and a non-contact scanning laser Doppler vibrometer (SLDV) for acquiring guided wave data. The global-local inspection is performed in two steps. First, a phased array configured of a small number of SLDV scan points (for example 10×10 points in a rectangular grid array) performs inspection over the entire plate to detect and locate damage (Figure 1a). Local areas are identified as potential damage regions for the second step. Then high density wavefield measurements are taken over the target damage areas and wavefield analysis is performed to quantitatively evaluate the damage (Figure 1b). For the proof of concept, the global-local approach is demonstrated on a carbon fiber reinforced polymer (CFRP) composite plate with two sites of impact-induced delamination damage. In the first step, the locations of two delamination sites are detected by the phased array method. In the second step, the delamination size and shape are evaluated through the wavefield analysis. The detected delamination location, size and shape agree well with those of ultrasonic C-scan.</p
Simulation of Guided Wave Interaction with In-Plane Fiber Waviness
No full textReducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness
Aerogel to simulate delamination and porosity defects in carbon-fiber reinforced polymer composites
No full textDispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Author's address:
No full textCan archives of audiovisual TV interviews be used to make authors more visible to students, and thereby reduce the learning gap between native and non-native language speakers in college classes? We examined students in a college course who learned about one scholar's ideas through watching an audiovisual TV interview (i.e., visible author format) and about another scholar's ideas through reading a formal text description (i.e., invisible author format). For the invisible author, native language speakers scored significantly higher than the non-native language speakers on a corresponding exam question (i.e., a cognitive measure), generated more words on the exam question (i.e., a motivational measure), and mentioned the author's name more often in answering the exam question (i.e., an affective measure). For the visible author, the groups did not differ on any of these measures. These findings provide evidence for the idea that making the author visible through audiovisual TV interviews can eliminate the learning gap between native and non-native language speakers. 3 Universities around the world serve students who are non-native speakers of th
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