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Reconciling the differences between tolerance specification and measurement methods

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Dimensional Metrology is the branch of science that determines length, angular, and geometric relationships within manufactured parts and compares them with required tolerances. The measurements can be made using either manual methods or sampled coordinate metrology (Coordinate measuring machines). Manual

Dimensional Metrology is the branch of science that determines length, angular, and geometric relationships within manufactured parts and compares them with required tolerances. The measurements can be made using either manual methods or sampled coordinate metrology (Coordinate measuring machines). Manual measurement methods have been in practice for a long time and are well accepted in the industry, but are slow for the present day manufacturing. On the other hand CMMs are relatively fast, but these methods are not well established yet. The major problem that needs to be addressed is the type of feature fitting algorithm used for evaluating tolerances. In a CMM the use of different feature fitting algorithms on a feature gives different values, and there is no standard that describes the type of feature fitting algorithm to be used for a specific tolerance. Our research is focused on identifying the feature fitting algorithm that is best used for each type of tolerance. Each algorithm is identified as the one to best represent the interpretation of geometric control as defined by the ASME Y14.5 standard and on the manual methods used for the measurement of a specific tolerance type. Using these algorithms normative procedures for CMMs are proposed for verifying tolerances. The proposed normative procedures are implemented as software. Then the procedures are verified by comparing the results from software with that of manual measurements.

To aid this research a library of feature fitting algorithms is developed in parallel. The library consists of least squares, Chebyshev and one sided fits applied on the features of line, plane, circle and cylinder. The proposed normative procedures are useful for evaluating tolerances in CMMs. The results evaluated will be in accordance to the standard. The ambiguity in choosing the algorithms is prevented. The software developed can be used in quality control for inspection purposes.

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Date Created
2014

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Familial Racial-ethnic Socialization of Multiracial Youth: A Qualitative Examination and Validation of the Multiracial Youth Socialization (MY-Soc) Scale

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Pew Research Center reported in 2015 that already one-in-seven infants born in the United States are Multiracial (Livingston, 2017). Therefore, the number of Multiracial families is growing, and there is a need to understand how parents are engaging in racial-ethnic

Pew Research Center reported in 2015 that already one-in-seven infants born in the United States are Multiracial (Livingston, 2017). Therefore, the number of Multiracial families is growing, and there is a need to understand how parents are engaging in racial-ethnic socialization, or the transmission of messages to Multiracial children about race, ethnicity, and culture (Atkin & Yoo, 2019; Hughes et al., 2006). I conducted a qualitative interview study with 20 Multiracial emerging adults to understand the types of racial-ethnic socialization messages Multiracial youth receive from their parents, and used these themes to inform the development and validation of the first measure of racial-ethnic socialization for Multiracial youth, the Multiracial Youth Socialization (MY-Soc) Scale.

Study 1 identified nine themes of racial-ethnic socialization content: cultural socialization, racial identity socialization, preparation for bias socialization, colorblind socialization, race conscious socialization, cultural diversity appreciation socialization, negative socialization, exposure to diversity socialization, and silent socialization. Study 2 utilized a sample of 902 Multiracial emerging adults to develop and validate the MY-Soc scale. Items were written to assess all of the themes identified in Study 1, with the exception of exposure to diversity socialization, and the survey was designed to collect responses regarding the socialization practices of two of the youths’ primary caregivers. The sample was split to run exploratory factor analysis and confirmatory factor analysis, finding support for a 62-item scale measuring all eight themes. The MY-Soc Scale was also supported by validity and reliability tests. The two studies advance the literature by increasing understanding of the racial-ethnic socialization experiences of Multiracial youth of diverse racial backgrounds. The MY-Soc Scale contributes an important tool for scholars and practitioners to learn which racial-ethnic socialization messages are promotive for Multiracial youth development in different contexts.

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Date Created
2020