21,465 research outputs found

    Meso-scale FDM material layout design strategies under manufacturability constraints and fracture conditions

    Get PDF
    In the manufacturability-driven design (MDD) perspective, manufacturability of the product or system is the most important of the design requirements. In addition to being able to ensure that complex designs (e.g., topology optimization) are manufacturable with a given process or process family, MDD also helps mechanical designers to take advantage of unique process-material effects generated during manufacturing. One of the most recognizable examples of this comes from the scanning-type family of additive manufacturing (AM) processes; the most notable and familiar member of this family is the fused deposition modeling (FDM) or fused filament fabrication (FFF) process. This process works by selectively depositing uniform, approximately isotropic beads or elements of molten thermoplastic material (typically structural engineering plastics) in a series of pre-specified traces to build each layer of the part. There are many interesting 2-D and 3-D mechanical design problems that can be explored by designing the layout of these elements. The resulting structured, hierarchical material (which is both manufacturable and customized layer-by-layer within the limits of the process and material) can be defined as a manufacturing process-driven structured material (MPDSM). This dissertation explores several practical methods for designing these element layouts for 2-D and 3-D meso-scale mechanical problems, focusing ultimately on design-for-fracture. Three different fracture conditions are explored: (1) cases where a crack must be prevented or stopped, (2) cases where the crack must be encouraged or accelerated, and (3) cases where cracks must grow in a simple pre-determined pattern. Several new design tools, including a mapping method for the FDM manufacturability constraints, three major literature reviews, the collection, organization, and analysis of several large (qualitative and quantitative) multi-scale datasets on the fracture behavior of FDM-processed materials, some new experimental equipment, and the refinement of a fast and simple g-code generator based on commercially-available software, were developed and refined to support the design of MPDSMs under fracture conditions. The refined design method and rules were experimentally validated using a series of case studies (involving both design and physical testing of the designs) at the end of the dissertation. Finally, a simple design guide for practicing engineers who are not experts in advanced solid mechanics nor process-tailored materials was developed from the results of this project.U of I OnlyAuthor's request

    Self-Supervised Learning to Prove Equivalence Between Straight-Line Programs via Rewrite Rules

    Full text link
    We target the problem of automatically synthesizing proofs of semantic equivalence between two programs made of sequences of statements. We represent programs using abstract syntax trees (AST), where a given set of semantics-preserving rewrite rules can be applied on a specific AST pattern to generate a transformed and semantically equivalent program. In our system, two programs are equivalent if there exists a sequence of application of these rewrite rules that leads to rewriting one program into the other. We propose a neural network architecture based on a transformer model to generate proofs of equivalence between program pairs. The system outputs a sequence of rewrites, and the validity of the sequence is simply checked by verifying it can be applied. If no valid sequence is produced by the neural network, the system reports the programs as non-equivalent, ensuring by design no programs may be incorrectly reported as equivalent. Our system is fully implemented for a given grammar which can represent straight-line programs with function calls and multiple types. To efficiently train the system to generate such sequences, we develop an original incremental training technique, named self-supervised sample selection. We extensively study the effectiveness of this novel training approach on proofs of increasing complexity and length. Our system, S4Eq, achieves 97% proof success on a curated dataset of 10,000 pairs of equivalent programsComment: 30 pages including appendi

    Composing games into complex institutions

    Get PDF
    Game theory is used by all behavioral sciences, but its development has long centered around tools for relatively simple games and toy systems, such as the economic interpretation of equilibrium outcomes. Our contribution, compositional game theory, permits another approach of equally general appeal: the high-level design of large games for expressing complex architectures and representing real-world institutions faithfully. Compositional game theory, grounded in the mathematics underlying programming languages, and introduced here as a general computational framework, increases the parsimony of game representations with abstraction and modularity, accelerates search and design, and helps theorists across disciplines express real-world institutional complexity in well-defined ways. Relative to existing approaches in game theory, compositional game theory is especially promising for solving game systems with long-range dependencies, for comparing large numbers of structurally related games, and for nesting games into the larger logical or strategic flows typical of real world policy or institutional systems.Comment: ~4000 words, 6 figure

    The Effectiveness of Using Code Switching in Teaching English on Higher Education

    Get PDF
    The occurence of using code switching in classroom appears for lecturer to explain topic, it also uses English-Indonesia, the students are difficult to understand when lecturer speaks English. The problem appears for students because of the difficulties to say something. This study aims to determine the factors that influence the use of code switching and the types of code switching used in learning English. The research method is descriptive qualitative. Collecting data by means of interviews, observations and video recordings. Data analysis is used to analyze information related to the use of code switching Indonesian English conversation. The participants of this study were two teachers who had experience of code switching while teaching. This study found five reasons teachers use code switching in teaching and learning English: discussing specific topics, making teaching and learning more practical, managing classes, building social relationships, and encouraging active student participation. From observations found three types of code switching used by teachers. The results showed that the use of code switching in learning English found 3 types of code switching, namely; (1) inter-sentential code switching occurred in 580 data (58%), (2) intra-sentential code switching occurred in 300 data (30%), and (3) Tag-code switching occurred in 127 data (12%). The factors behind the use of code switching in learning English are structural linguistic factors, internal psycholinguistic factors, and external social factors. The most dominant factor behind the occurrence of code switching is the structural linguistic factor, namely students do not master English. The teacher applies code switching to facilitate students to more easily understand the material being presented

    The Integration of Ideological and Political Elements into English Reading Course

    Get PDF
    Against the background of implementing ideological and political education, foreign language teachers should deeply explore the ideological and political elements such as excellent cultures, broad views on the world, positive outlook on life, correct values, and integrate them into language teaching. English reading course is a main platform for English majors to train their basic language skills. It involves not only the training of language skills, but also the guidance of students’ correct learning methods, the improvement of critical thinking ability and the cultivation of their humanistic quality. This study expounds the necessity and feasibility of implementing ideological and political education in English Reading course. Taking the teaching design of Rachel Carson’s Silent Spring as an example, this paper discusses the ways to integrate ideological and political elements into the course from the aspects of teaching content, teaching objectives, teaching process, teaching methods and teaching assessment, to achieve the goal of whole person education

    Intercultural communication methodology: teaching sciences and engineering students

    Get PDF
    The problem area of this research paper focuses on the priority functions of the language sphere of the being mentality necessarily reflecting the state documents on education, methodology of scientific and methodical support for the implementation of educational programs of language education for training students of non-linguistic departments of universities in line with the axiology within the current educational program research of the eco-system spaces of international language education in Russia. Current Scientific Scholarship in terms of the intercultural approach needs to be created for linguistic security via making the outmost of the language programs for SP. The goal of this article is threefold: a) to design Knowledge Content, Technology and Evaluation Concepts of the target Model, b) to substantiate the integration characteristics of intercultural communication at universities (Natural Sciences and Engineering), c) to clarify the integration characteristics of intercultural communication within the innovations of national education in the third millennium, based on topical issues of the polyphony of the eco-system spaces. The latter reflects the priority dominant values due to the cognitive, developmental and educational functions in line with positive trends requiring thorough attention of both the university pedagogical community and teachers of general education organizations

    In Search of Phonetic Evidence for Prosodically-Motivated Aspiration

    Get PDF
    This thesis examines the production and perception of aspiration in all possible levels of stress and word positions attested under the left-edge prosodic description theorized by Kiparsky (1979), Withgott (1982), and Jensen (2000), as well as in all attested environments for unaspirated voiceless stops. Through the metric of voice onset time (VOT), I phonetically test the realization of aspiration and examine its perception as categorical in several environments that are not acoustically salient. Through a production study and two linked perception studies I provide acoustic evidence in support of the phonological definition of categorical aspiration as prosodically-motivated in English, and clarify the behavior of aspiration in two related stress lapse environments

    He’s like, “My Nan loves that naan bread” quotative be+like and mimetic performance among migrants to St. John’s NL

    Get PDF
    This thesis examines quotative verb use and mimetic performance among migrants to St. Johns, Newfoundland. The first part examines the variation and distribution of quotative verbs among this community, implements variable rule analysis and delves into which grammatical and social constraints condition the choice of quotative verbs by these speakers. The second part investigates the properties of mimetic speech and explores how these individuals create voices using the acoustic properties of vowels. These topics are examined through the lens of social network theory (Milroy 1987) and performance speech. I propose a framework of sociolinguistic comfort that incorporates these concepts to account for the patterns of quotative and mimetic performance. As our world grows ever more global, understanding the ways migrant speakers learn to perform identity, incorporate highly regionalized features, and yet remain connected to their adopted community is essential

    Queer spies in British Cold War culture: literature, film, theatre and television

    Get PDF
    This PhD thesis investigates how male homosexuality has been represented in British spy fiction from the 1950s to the 2010s in multiple media: literature, film, television and theatre. Due mainly to the betrayal of the Cambridge Spy ring around the middle of the century, British culture has associated spies with homosexuality, while the wider Anglophone world was in the grip of a homophobic atmosphere created by McCarthy's Red Scare. My thesis explores how this history is reflected in the spy genre from the Cold War to the present, in which male homosexuality and secret agency intersect as “queer”, in so far as they were both considered to be discreet and criminal, existing outside of the heteronormative order. By following multiple texts across media and time, I discuss how some writers, television and film directors and actors update queer identity in spy fiction, creating a shifting image of queer spies through decades. I refer to the findings of adaptation studies and queer studies, along with numerous studies on spy fiction. I conclude that the interrelation of different media has contributed to the re-drawing of queer identity in spy fiction. These developments have enabled the spies' queer identity to transcend its pejorative history in British culture, towards its more flexible and pliant sense which is designated by the term's modern usage. I also discuss that spies’ homosexuality has been represented as a fleeting ghost in most of the texts examined, hovering on the margins of pages and screen. Although homosexuality is not “the love that dare not speak its name” anymore, clandestine queer spies have been preserved as spectral others in the genre for many years. Spy fiction is a cultural repository retaining the memory of violence inflicted against those who have been called “queer” in twentieth century Britain, and the spectral nature of queer spies narrates this history reaching back to the Oscar Wilde trial in 1895, from which point British queer identity as we know now developed. This thesis benefits the study of spy fiction by filling a gap in the investigation of homosexual representation. It also contributes to the field of gender studies of literature, film, television, and theatre by illustrating queer history in a genre which has not received a great deal of focus on its representation of homosexuality. Spy fiction occupies a central position in British popular culture, and by exploring this genre in terms of homosexuality, this research will identify the role which same-sex desire has historically played in the British cultural imagination

    Um modelo para suporte automatizado ao reconhecimento, extração, personalização e reconstrução de gráficos estáticos

    Get PDF
    Data charts are widely used in our daily lives, being present in regular media, such as newspapers, magazines, web pages, books, and many others. A well constructed data chart leads to an intuitive understanding of its underlying data and in the same way, when data charts have wrong design choices, a redesign of these representations might be needed. However, in most cases, these charts are shown as a static image, which means that the original data are not usually available. Therefore, automatic methods could be applied to extract the underlying data from the chart images to allow these changes. The task of recognizing charts and extracting data from them is complex, largely due to the variety of chart types and their visual characteristics. Computer Vision techniques for image classification and object detection are widely used for the problem of recognizing charts, but only in images without any disturbance. Other features in real-world images that can make this task difficult are not present in most literature works, like photo distortions, noise, alignment, etc. Two computer vision techniques that can assist this task and have been little explored in this context are perspective detection and correction. These methods transform a distorted and noisy chart in a clear chart, with its type ready for data extraction or other uses. The task of reconstructing data is straightforward, as long the data is available the visualization can be reconstructed, but the scenario of reconstructing it on the same context is complex. Using a Visualization Grammar for this scenario is a key component, as these grammars usually have extensions for interaction, chart layers, and multiple views without requiring extra development effort. This work presents a model for automated support for custom recognition, and reconstruction of charts in images. The model automatically performs the process steps, such as reverse engineering, turning a static chart back into its data table for later reconstruction, while allowing the user to make modifications in case of uncertainties. This work also features a model-based architecture along with prototypes for various use cases. Validation is performed step by step, with methods inspired by the literature. This work features three use cases providing proof of concept and validation of the model. The first use case features usage of chart recognition methods focused on documents in the real-world, the second use case focus on vocalization of charts, using a visualization grammar to reconstruct a chart in audio format, and the third use case presents an Augmented Reality application that recognizes and reconstructs charts in the same context (a piece of paper) overlaying the new chart and interaction widgets. The results showed that with slight changes, chart recognition and reconstruction methods are now ready for real-world charts, when taking time, accuracy and precision into consideration.Os gráficos de dados são amplamente utilizados na nossa vida diária, estando presentes nos meios de comunicação regulares, tais como jornais, revistas, páginas web, livros, e muitos outros. Um gráfico bem construído leva a uma compreensão intuitiva dos seus dados inerentes e da mesma forma, quando os gráficos de dados têm escolhas de conceção erradas, poderá ser necessário um redesenho destas representações. Contudo, na maioria dos casos, estes gráficos são mostrados como uma imagem estática, o que significa que os dados originais não estão normalmente disponíveis. Portanto, poderiam ser aplicados métodos automáticos para extrair os dados inerentes das imagens dos gráficos, a fim de permitir estas alterações. A tarefa de reconhecer os gráficos e extrair dados dos mesmos é complexa, em grande parte devido à variedade de tipos de gráficos e às suas características visuais. As técnicas de Visão Computacional para classificação de imagens e deteção de objetos são amplamente utilizadas para o problema de reconhecimento de gráficos, mas apenas em imagens sem qualquer ruído. Outras características das imagens do mundo real que podem dificultar esta tarefa não estão presentes na maioria das obras literárias, como distorções fotográficas, ruído, alinhamento, etc. Duas técnicas de visão computacional que podem ajudar nesta tarefa e que têm sido pouco exploradas neste contexto são a deteção e correção da perspetiva. Estes métodos transformam um gráfico distorcido e ruidoso em um gráfico limpo, com o seu tipo pronto para extração de dados ou outras utilizações. A tarefa de reconstrução de dados é simples, desde que os dados estejam disponíveis a visualização pode ser reconstruída, mas o cenário de reconstrução no mesmo contexto é complexo. A utilização de uma Gramática de Visualização para este cenário é um componente chave, uma vez que estas gramáticas têm normalmente extensões para interação, camadas de gráficos, e visões múltiplas sem exigir um esforço extra de desenvolvimento. Este trabalho apresenta um modelo de suporte automatizado para o reconhecimento personalizado, e reconstrução de gráficos em imagens estáticas. O modelo executa automaticamente as etapas do processo, tais como engenharia inversa, transformando um gráfico estático novamente na sua tabela de dados para posterior reconstrução, ao mesmo tempo que permite ao utilizador fazer modificações em caso de incertezas. Este trabalho também apresenta uma arquitetura baseada em modelos, juntamente com protótipos para vários casos de utilização. A validação é efetuada passo a passo, com métodos inspirados na literatura. Este trabalho apresenta três casos de uso, fornecendo prova de conceito e validação do modelo. O primeiro caso de uso apresenta a utilização de métodos de reconhecimento de gráficos focando em documentos no mundo real, o segundo caso de uso centra-se na vocalização de gráficos, utilizando uma gramática de visualização para reconstruir um gráfico em formato áudio, e o terceiro caso de uso apresenta uma aplicação de Realidade Aumentada que reconhece e reconstrói gráficos no mesmo contexto (um pedaço de papel) sobrepondo os novos gráficos e widgets de interação. Os resultados mostraram que com pequenas alterações, os métodos de reconhecimento e reconstrução dos gráficos estão agora prontos para os gráficos do mundo real, tendo em consideração o tempo, a acurácia e a precisão.Programa Doutoral em Engenharia Informátic
    corecore