Academic literature on the topic 'Differential Aptitude Tests – Evaluation'
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Journal articles on the topic "Differential Aptitude Tests – Evaluation"
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Hativa, Nira, and Avigdor Teper. "Differential Effectiveness of Three Color Treatments in Learning Geometric Concepts via Computer-Guided Teaching." Journal of Educational Computing Research 4, no. 3 (August 1988): 303–20. http://dx.doi.org/10.2190/3bwb-p2v2-11q7-uw12.
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This study examined the differential effects of three color treatments incorporated into microcomputer software on the learning of geometric concepts by students with differential aptitudes. The color treatments were: monochrome, functional (the use of color for cueing), and nonfunctional (the indiscriminate use of color). The experimental software provided teachers with a detailed lesson outline to be used with one large-screen monitor for whole-class instruction using the discussion or recitation method of teaching. Ninth-grade students ( N = 109) were randomly assigned to the treatment groups. All students answered two aptitude tests, two geometric pretests, two geometric immediate posttests, the same posttests administered one month later, and an attitude questionnaire. All three experimental forty-minute lessons were delivered by the same teacher using the same software varying only the color treatment. Results revealed significantly better immediate and delayed learning of the functional group over both other groups with the low-aptitude students benefitting the most from the cueing provided by the functional-color software. Although high-aptitude students did not benefit more from the functional treatment than from the other two treatments, they showed the most positive attitudes toward this treatment whereas low aptitude students did not show any preference for the color system involved.
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Goble, David. "Using the Differential Aptitude Tests for Selection and Prediction in Vocational Education and Training." Australian Journal of Career Development 7, no. 1 (November 1998): 20–23. http://dx.doi.org/10.1177/103841629800700107.
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The Differential Aptitude Tests (DAT) were first published in 1947 and have undergone numerous revisions since then. The tests were standardised in Australia and New Zealand in 1983 and are widely used by guidance counsellors, vocational psychologists, schools and business organisations. This paper reports the findings of a study focusing on the validity of the DAT as a predictor of performance in a post-secondary technical training program. Four subtests from the eight-test battery were used to predict student performance in two electronic engineering units: Electronic Principles and Digital Electronics. The sample consisted of 213 electronic engineering students with a mean age of 21.4 years (SD = 9.5 years). Principal Components Analysis and unweighted least squares factor analysis suggested that the DAT measures general ability and that its differential nature is limited. Hierarchical multiple regression was performed to measure the strength of association between the predictor variables and the criterion measures. The regression analysis indicated that general ability accounted for most of the variance in the criterion measures, ranging between 37 and 41% while specific abilities added, at most, 4% to these figures.
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Betz, Armin. "Evaluation of Personality Traits for a Successful Career of Engineers." Applied Mechanics and Materials 657 (October 2014): 1056–60. http://dx.doi.org/10.4028/www.scientific.net/amm.657.1056.
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Various research on aptitude testing has been accomplished yet [1,2,. Experiences from many years of HR consulting and knowledge of the industrys needs regarding to and lack of specific scientific research in aptitude testing for engineers emerged into research acivities in this field. The paper presents the data and main results of the field of aptitude testing for engineers. Its present situation as well as the reasons for that are considered and its necessity is shown. The gotten insights are presented: the existence of personality traits typical for engineers, the existence of key criteria and deduction of HR development measures necessary for a career. A newly developed personality test was applied to the occupational area of engineers. With more than 1400 tests conducted, many deductions were possible.Through the innovative approach of standard profiles of corresponding average groups rather than with demografic equivalent results could be derived. These are typical traits on the one side and development areas on the other.
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Setiawati, Farida Agus. "Aptitude Test's Predictive Ability for Academic Success in Psychology Student." Psychological Research and Intervention 3, no. 1 (September 30, 2020): 1–12. http://dx.doi.org/10.21831/pri.v3i1.34731.
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The developments that occur in psychological measurement have an effect on the development of the quality of the tests used. Differential Aptitude Test (DAT) is a form of psychological test used to measure a person's talent. Measurement of aspects of talent needs to be proven on the success of post-aptitude test studies. Therefore, this study aims to examine: (1) the predictive validity of differential aptitude tests in predicting study success in psychology study programs, and (2) which subtests are influential in predicting the success of studies in psychology study programs. Data collection was carried out using test techniques and documentation techniques. The research subjects were 62 students majoring in psychology at Yogyakarta State University in the academic year 2016/2017. The data obtained were then analyzed using multiple linear regression analysis techniques, where the subtest scores on the DAT were treated as predictors and the Grade Point Average scores were treated as the dependent variable. Based on the results of the analysis, it can be concluded that: (1) the DAT test can predict the success of the study in the psychology study program; and (2) the subtest in DAT that has the most influence in predicting the success of the study in the psychology study program is the verbal subtest and the numerical subtest
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Li, Shaofeng. "THE CONSTRUCT VALIDITY OF LANGUAGE APTITUDE." Studies in Second Language Acquisition 38, no. 4 (December 18, 2015): 801–42. http://dx.doi.org/10.1017/s027226311500042x.
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A meta-analysis was conducted to examine the construct validity of language aptitude by synthesizing the existing research that has been accumulated over the past five decades. The study aimed to provide a thorough understanding of the construct by aggregating the data reported in the primary research on its correlations with other individual difference variables and with second language (L2) achievement. A total of 66 studies were retrieved that contributed effect sizes based on 109 unique samples and 13,035 foreign language learners. The results revealed that (1) aptitude was independent of other cognitive and affective factors: it was distinct from motivation, had a negative correlation with anxiety, and overlapped with, but was distinguishable from, intelligence; (2) executive working memory was more strongly associated with aptitude and aptitude components than phonological short-term memory; (3) aptitude measured using full-length tests was a strong predictor of general L2 proficiency, but it had low predictive validity for vocabulary learning and L2 writing; and (4) different aptitude components demonstrated differential predictive validity for different aspects of learning. The findings are useful for tackling a number of conundrums surrounding language aptitude and shed light on how to reconceptualize the construct and reorient the research.
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Wang, Mao-Jiun J., Colin G. Drury, and Michael L. Raulin. "An Evaluation of the IPI-Inspection Test." Proceedings of the Human Factors Society Annual Meeting 30, no. 13 (September 1986): 1296–300. http://dx.doi.org/10.1177/154193128603001314.
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The Color Video Comparator (CVC), a semiautomated inspection device was used to assess the validity of a commercially available selection test for inspectors published by Industrial Psychology, Inc. (IPI). The IPI battery included five aptitude subtests (Blocks, Dimensions, Tools, Precision, and Parts). Factor analysis was performed to determine the underlying factor patterns measured by the IPI-inspection tests. Also, Pearson correlations were performed to evaluate the strength of associations between IPI-inspection tests scores and different inspection performance measures. The results, in general, suggested that the IPI-inspection tests which measure multiple attributes demonstrate a predictive ability for many performance measures of the CVC inspection task.
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Oosterveld, Paul, and Harrie C. M. Vorst. "Note on Reliability and Validity of Self-Evaluation of Ability Scales." Perceptual and Motor Skills 82, no. 3 (June 1996): 991–94. http://dx.doi.org/10.2466/pms.1996.82.3.991.
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A four-scale questionnaire on self-evaluation of ability was developed, testing 402 pupils. The Differential Aptitude Test was used as the criterion for estimating validity. Values of Cronbach alpha for the Verbal, Reasoning, Spatial, and Numerical Ability scales ranged from .74 to .86. The Reasoning Ability scale lacked validity.
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Yilmaz, Yucel, and Gisela Granena. "IMPLICITNESS AND EXPLICITNESS IN COGNITIVE ABILITIES AND CORRECTIVE FEEDBACK." Studies in Second Language Acquisition 43, no. 3 (May 6, 2021): 523–50. http://dx.doi.org/10.1017/s0272263120000601.
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AbstractThis aptitude–treatment interaction study investigated the extent to which explicit and implicit cognitive abilities are differentially related to learning outcomes under two corrective feedback conditions. One hundred and thirteen intermediate English learners of Spanish were randomly assigned to an implicit feedback (recast), explicit feedback (explicit correction), or control group after completing tests from two aptitude batteries (High-Level Language Aptitude Battery [Hi-LAB] and LLAMA). Linguistic improvement on noun-adjective gender agreement and Differential Object Marking was assessed using grammaticality judgment and oral production tasks. Results showed that implicit but not explicit abilities were relevant for the acquisition of gender agreement under implicit feedback as measured by grammaticality judgments. In contrast, explicit but not implicit abilities were relevant for the acquisition of object marking under explicit feedback as measured by oral production. These results lent support to a double dissociation, but they also suggested higher-order interaction effects between the type of cognitive ability, outcome measure, and target structure.
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Alkhadher, Othman, David D. Clarke, and Neil Anderson. "Equivalence and predictive validity of paper-and-pencil and computerized adaptive formats of the Differential Aptitude Tests." Journal of Occupational and Organizational Psychology 71, no. 3 (September 1998): 205–17. http://dx.doi.org/10.1111/j.2044-8325.1998.tb00673.x.
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Ismail, Fajri. "THE EVALUATION OF CURRICULUM IMPLEMENTATION AT TARBIYAH FACULTY IAIN RADEN FATAH PALEMBANG." JISAE: JOURNAL OF INDONESIAN STUDENT ASSESMENT AND EVALUATION 1, no. 1 (June 1, 2015): 12. http://dx.doi.org/10.21009/jisae.011.02.
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This research aims to figure out the facts of the objective conditions of the curriculum implementation at Tarbiyah Faculty IAIN Raden Fatah Palembang. The curriculum evaluation used the Evaluation Programme for Innovative Curriculum (EPIC) Model, consisting of three components namely: 1) instruction, 2) institutional, and 3) learning achievement. This research used an evaluative programme to make judgments and decisions of a programme or curriculum. The evaluation results for these three components are: (1) instruction: learning burdens and lecturers’ quality are good, but there are still many errors in the presentation, coding, credits of institutional courses, faculty courses, and study program courses, low in task variation, low in the number of hours of meetings, many mistakes in curriculum structure, and low in facilities and infrastructure, (2) institutional: entrance tests for the students of Tarbiyah Faculty IAIN Raden Fatah do not include aptitude tests, lecturers who have magister qualification is good, but low on doctoral qualification, and ratio between lecturers to students is not ideal, (3) learning achievement: students’ mastery of teaching skills and attitudes is good, but very low in the mastery of pedagogical skills and teacher education. Recommendations of this research are 1) revise curriculum, 2) use the aptitude test to select new students, 3) increase academic qualifications of lecturers, and 4) revise comprehensive examination system.
Dissertations / Theses on the topic "Differential Aptitude Tests – Evaluation"
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Higgins, Oyd Hugh II. "Item position effects and differential item functioning for African-American and White examinees completing the arithmetic reasoning subtest of the preliminary item tryout version of Form E of the General Aptitude Test Battery." Scholarly Commons, 1997. https://scholarlycommons.pacific.edu/uop_etds/2602.
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Schmitt and Dorans (1990) hypothesized that one possible reason for apparent test bias on the Scholastic Aptitude Test (SAT) against African Americans was related to a difference in processing speed between White and African American examinees. They based this hypothesis on an analysis of data generated by the administration of the SAT. Specifically, if one omitted those items that African Americans did not reach, the differential item functioning that led to bias against African Americans virtually disappeared. This study utilized data collected during the preliminary item tryout phase of Form E of the General Aptitude Test Battery (GATB) to examine the extent to which item position effects might be linked to differential item functioning (DIF). During the item pretest study, a set of arithmetic reasoning items was presented to a nationwide sample of examinees. Roughly half of the examinees were presented the items in forward order and the other half were presented the items in reverse order. This allowed an evaluation of the extent to which an item's ordinal position affected examinee performance. The study failed to provide direct evidence for Schmitts' and Dorans' (1990) hypothesis due to the fact that very little DIF was identified. However, several troubling observations emerged. First, White examinees answered 32 out of the 33 items correctly at a greater proportion than African American examinees (p $<$.05). Second, there were statistically significant differences between how White and African American examinees selected incorrect item alternatives. Third, when evaluated using a biserial or point-biserial correlation coefficient as an estimator of the effectiveness of an item at discriminating between high and low ability examinees, the test items tended to predict scores for White examinees better than for African American examinees indicating that they may not be a valid measure of the African American examinees' arithmetic reasoning ability. Finally, there is a significant correlation between item position and the difference between White and African American examinee performance. Items administered early in the examination tended to work more equally well for both groups while items administered later tended to work better for White examinees than for African American examinees.
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Ip, Tsang Chui-hing Betty, and 葉鈤翠卿. "The construct validity of the aptitude test for prevocational schools." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1986. http://hub.hku.hk/bib/B3862770X.
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Foucault, Valérie. "Evaluation de l'aptitude physique d'une population active : le MST (mesure du seuil de tolérance à l'effort)." Caen, 1991. http://www.theses.fr/1991CAEN3056.
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Poisot, Sophie. "SIGYCOP, intérêt et utilisation du sigle P3 en pratique médico-militaire." Bordeaux 2, 1995. http://www.theses.fr/1995BOR2M151.
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Simpson, Angela Gumede. "Aptitude, school grades, Cambridge examination results and university performance : the Swaziland case." Virtual Press, 1990. http://liblink.bsu.edu/uhtbin/catkey/720159.
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The purpose of this study was to examine the relationship among locality of school, type of school, gender of student, school GPA (GPA), aptitude (MEANAPT), Cambridge English Language (CAMENG), Cambridge class (CAMCLASS), and Cambridge aggregate (CAMAGGR). A second purpose of this research was to determine the relationship among GPA, MEANAPT, CAMENG, CAMCLASS, CAMAGGR, university registration status (STATUS), and average university grade (UNIMEAN) after 2 years at the University of Swaziland (UNISWA). The study was divided into two parts. In the first part, locality of school, type of school, and gender of student were the independent variables; GPA, MEANAPT, CAMENG, CAMCLASS, and CAMAGGR were the dependent variables. In the second part, performance at UNISWA, as measured by either STATUS or UNIMEAN, was the dependent variable; CAMENG, CAMCLASS, CAMAGGR, GPA, and MEANAPT were the independent variables.Answers to questions on Part 1 of the study were determined by computing means, standard deviations, and F-tests for differences between means for GPA, MEANAPT, CAMENG, CAMCLASS, and CAMAGGR for each of the general questions. Data were analyzed using Pearson r and multiple regression to answer Part 2 questions.The results of this study indicate that students enrolled in rural and government schools were outperformed by those attending urban and government-aided schools on all the measures. Although males outperformed females on the local Swaziland measures, school GPA and aptitude, there were no significant differences between males and females when the Cambridge examination scores were considered. The Cambridge examination appears to be neither efficient nor economical when used to identify the successful African student once he or she has been admitted to a local university. The same is true for the measures designed and currently used by local Swaziland educators. Swaziland officials may have to look elsewhere for predictors of university performance.Department of Educational Psychology
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Smalley, Judith Ellen. "The differential predictive validity of the Spanish and English versions of the Peabody Picture Vocabulary Test." Scholarly Commons, 1995. https://scholarlycommons.pacific.edu/uop_etds/2797.
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The purpose of this study was to determine the predictive validity of the Spanish and English versions of the Peabody Picture Vocabulary Test for entering limited English proficient (LEP) Spanish and monolingual English kindergarten students. The criterion was reading achievement as measured by the Total Reading subtest of the Comprehensive Tests of Basic Skills (CTBS) and the Spanish Assessment of Basic Education (SABE). In addition, percentage of instructional time in Spanish was examined as a variable which may combine with the vocabulary scores to predict achievement for the Spanish speaking students. Selected for the study were 355 monolingual English speaking and 208 monolingual Spanish-speaking kindergarten students from a single district in central California. The LEP students included were those who scored a "one," no English, on the Bilingual Syntax Measure (BSM) upon entering kindergarten. Students included in the study were selected over 3 school years and 25 kindergarten teachers. Ninety percent of the district's students were on free or reduced cost lunch. The results of this study indicate there is a statistically significant relationship between entering kindergarten students' vocabulary scores and end of the first grade reading achievement but the vocabulary scores differentially predict achievement for the Spanish and English students. English speaking students scored significantly higher in reading achievement than Spanish-speaking students. The amount of time spent instructing in Spanish during the first grade combines with the students' language and vocabulary scores for a greater increment in the prediction of reading achievement. LEP Spanish-speaking students instructed more than 75% of the time in Spanish at the first grade level scored significantly higher in reading achievement than those instructed less than 75% of the time.
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Wei, Min. "A Structural and Psychometric Evaluation of a Situational Judgment Test: The Workplace Skills Survey." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc799488/.
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Some basic but desirable employability skills are antecedents of job performance. The Workplace Skills Survey (WSS) is a 48-item situational judgment test (SJT) used to assess non-technical workplace skills for both entry-level and experienced workers. Unfortunately, the psychometric evidence for use of its scores is far from adequate. The purpose of current study was two-fold: (a) to examine the proposed structure of WSS scores using confirmatory factor analysis (CFA), and (b) to explore the WSS item functioning and performance using item response theory (IRT). A sample of 1,018 Jamaican unattached youth completed the WSS instrument as part of a longitudinal study on the efficacy of a youth development program in Jamaica. Three CFA models were tested for the construct validity of WSS scores. Parameter estimations of item difficulty, item discrimination, and examinee’s proficiency estimations were obtained with item response theory (IRT) and plotted in item characteristics curves (ICCs) and item information curves (IICs). Results showed that the WSS performed quite well as a whole and provided precise measurement especially for respondents at latent trait levels of -0.5 and +1.5. However, some modifications of some items were recommended. CFA analyses showed supportive evidence of the one-factor construct model, while the six-factor model and higher-order model were not achieved. Several directions for future research are suggested.
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Martin, Summer M. G. "Criterion Validity of Common Career Interest Inventories: Relative Efficacy with High School Seniors." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc799471/.
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Professional school counselors frequently use career interest inventories as part of a comprehensive guidance program to help students create a post-secondary school plan. The present study evaluates the validity of three commonly used interest inventories, the Myers-Briggs Type Indicator, Self-Directed Search, and Strong Interest Inventory on field of study choice for graduating high school seniors (N = 616) from a large, suburban high school in Texas. Students identified their intended postsecondary field of study category, were randomly assigned using stratification to three groups, and each group completed a different inventory. Group membership was evaluated to establish covariate balance on a wide variety of indicators. Data from each group was evaluated to determine the extent to which the inventory predicted the chosen field of study, as well as Other and Undeclared categories using logistic regression models. None of the inventory models suggest that the inventory accurately predicts Other or Undeclared outcomes. For students selecting intended postsecondary fields of study, the Self Directed Search predicts such outcomes better than other measures. Professional school and career counselors should consider the SDS in addition to narrative counseling strategies to add greater precision with career decision making among clients and students.
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Parker, Kathy L. "Construct validity of the Differential Ability Scales with a mentally handicapped population : an investigation into the interpretability of cluster scores." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/1019480.
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The purpose of the present study was to investigate the construct validity of the Differential Ability Scales (DAS) with a mentally handicapped population. The DAS is an individually administered, standardized test of intelligence. The stated purposes of the DAS are to provide a composite measure of conceptual reasoning abilities for classification and placement decisions and to provide a reliable profile of relative strengths and weaknesses for diagnostic purposes. With these goals in mind, it follows that this cognitive measure would be used often with mentally handicapped students. The DAS was developed using an hierarchical model based upon exploratory and confirmatory factor analyses. The model assumes that ability measures or subtests will load on a general factor g and will form subfactors at a lower level. The model also assumes that as children get older, the number of subfactors will increase because of development and differentiation of abilities. How mentally handicapped children would fit into this model was the subject of the current research.Using a sample of 100 mildly and moderately handicapped children ages 8 years, 0 months to 17 years, 5 months, confirmatory factor analysis was used to explore the factor structure of the DAS with this population. Three separate models were investigated: Model I, in which a one factor solution was proposed, Model II, in which two factors, Verbal Ability and Nonverbal Ability, were proposed, and Model III, in which three factors, Verbal Ability, Nonverbal Reasoning Ability, and Spatial Ability, as proposed by the test's authors, were investigated. Results of the analyses support the use of a one factor interpretation when using the DAS with mentally handicapped students. In practice, only the broadest score, the General Conceptual Ability Score (GCA), can be interpreted with confidence. Further, case study investigation illustrates the inconsistencies encountered in scoring at the lower end of the norms, as well as in using the outof-level procedure proposed by the test's authors.Department of Educational Psychology
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Li, Yanju. "Item Discrimination and Type I Error Rates in DIF Detection Using the Mantel-Haenszel and Logistic Regression Procedures." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1339428784.
Full textBooks on the topic "Differential Aptitude Tests – Evaluation"
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IQ and psychometric tests: Assess your personality, aptitude and intelligence. London: Kogan Page, 2010.
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Carter, Philip J. Test and assess your IQ: Numerical, verbal, and spatial aptitude tests. London: Kogan Page Ltd., 2008.
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Staples, Jane G. Measurement comparability of paper-and-pencil and multimedia vocational assessments. Iowa City, Iowa: ACT, 1999.
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IQ and aptitude tests: Assess your verbal, numerical and spatial reasoning skills. Philadelphia: Kogan Page Ltd, 2011.
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IQ and aptitude tests: Assess your verbal your verbal, numerical, and spatial reasoning skills. London: KoganPage, 2012.
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IQ and aptitude tests: Assess your verbal, numerical, and spatial reasoning. London: Kogan Page, 2007.
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Prediger, D. J. Basic structure of work-relevant abilities. Iowa City, IA: ACT, Inc., 1998.
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Prediger, D. J. Basic structure of work-relevant abilities. Iowa City, Iowa: ACT, 1998.
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G, Hays Danica, ed. A counselor's guide to career assessment instruments. 6th ed. Broken Arrow, OK: National Career Development Association, 2013.
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Prediger, D. J. Basic structure of work-relevant abilities. Iowa City, Iowa: ACT, 1998.
Find full textBook chapters on the topic "Differential Aptitude Tests – Evaluation"
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Meir, Elchanan I., and Nurit Adler. "Aptitude tests as the predictor of success in the Israeli matriculation." In Assessment & Evaluation, 209–13. Routledge, 2019. http://dx.doi.org/10.4324/9781315020600-17.
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Singh, Neerja. "Impact of Learning Analytics on the Assessment of a Curriculum-Based Test." In Impact of Learning Analytics on Curriculum Design and Student Performance, 56–70. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-5369-4.ch005.
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The assessment is not limited to only the measurement of memorized awareness; all the way through it, the various abilities of the individual are considered. Such evaluation of abilities is of great significance in obtaining knowledge about the individual's aptitude, interest, capability, and capacity. The evaluation of ability is now done with the help of psychological tests. The different types of psychological tests that are used in measuring intelligence and different types of abilities. It is worth consideration that the psychological tests are constructed on certain general principles and in this connection some specific conditions and characteristics are always kept in mind. In this chapter, the author's aim is to describe these principles and the specific conditions as well as to assess the importance of learning analytics on this platform.
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Douglas, Raymond S., and Robert A. Goldberg. "Evaluation and Spectrum of Orbital Diseases." In Surgery of the Eyelid, Lacrimal System, and Orbit. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195340211.003.0024.
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Although orbital disorders are not frequently encountered in the comprehensive ophthalmologist’s practice, it is essential to be able to diagnose patients with orbital disease and manage them accordingly. Various disease processes can affect the orbit. This chapter endeavors to provide a thoughtful, stepwise, and logical approach to the evaluation of orbital disease. The discussion begins with differential diagnosis, adds an intelligent history-taking and physical examination, and then focuses on efficient use of diagnostic tests to finally arrive at the correct diagnosis. The staging and management of two common orbital disorders, orbital inflammation and thyroid-associated ophthalmopathy, will also be discussed. The differential diagnosis of orbital disease is extensive, and most listings of orbital disease divide the causes between histopathologic and mechanistic categories. This type of grouping is intellectually sound and scientifically useful but does not provide a framework that the clinical practitioner can easily grasp and directly use in sorting through the differential diagnosis of any given patient. In broad terms, orbital disease can be considered in terms of location, extent, and biologic activity. The classification used in this chapter is broken down along clinical lines and takes advantage of the fact that the orbit has a somewhat limited repertoire of ways that it can respond to pathologic conditions. Orbital disease can be categorized into five basic clinical patterns: inflammatory, mass effect, structural, vascular, and functional. Although many cases cross over into several categories, the vast majority of clinical presentations fit predominantly into one of these patterns. As the clinician walks through each step of the evaluation process—history, physical examination, laboratory testing, orbital imaging—a conscious effort should be made to categorize the presentation within this framework. If the practitioner approaches orbital disease with this framework of discrete patterns of clinical presentation, then at every step of the diagnostic pathway (history, physical examination, orbital imaging studies, and special tests), he or she can draw from a defined set of differential diagnoses that characterize each pattern of orbital disease and use that information to efficiently and confidently orchestrate diagnosis and management.
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Adams, Andrea C. "The Neurologic Examination." In Mayo Clinic Essential Neurology, 1–41. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190206895.003.0001.
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The neurologic examination is the most important part of the evaluation of a patient who has neurologic symptoms or disease. The information obtained from the history and physical examination is needed to generate a differential diagnosis, to select the appropriate diagnostic tests, and to initiate appropriate therapy.
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Martini, Ross P., and Ines P. Koerner. "Neurologic Emergencies." In Oxford Textbook of Neuroscience and Anaesthesiology, edited by George A. Mashour and Kristin Engelhard, 125–36. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780198746645.003.0010.
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The primary goal of the neuroanaesthetist and neurointensivist is to preserve brain structure and function, especially in the setting of neurologic insults. Neurologic emergencies can also develop peri-operatively in patients undergoing non-neurosurgical procedures, which the general anaesthetist should be prepared to manage. This chapter on neurologic emergencies discusses herniation syndromes (including pathophysiology of intracranial hypertension, symptoms of herniation, and therapies to reduce intracranial pressure and reverse herniation). It also covers coma (including differential diagnoses of postoperative coma, clinical evaluation of the comatose patient, CT imaging, advanced tests, and directed therapies). Finally, it discusses key aspects of ischaemic stroke, status epilepticus, and transition of care.
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Compton, Michael T., and Beth Broussard. "What Diagnoses are Associated with Psychosis?" In The First Episode of Psychosis. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195372496.003.0011.
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As described in Chapter 1, psychosis is a syndrome. This syndrome can include a number of different signs and symptoms (see Chapter 2 on What Are the Symptoms of Psychosis?). In this chapter, we discuss the different diagnoses that may relate to psychosis. A diagnosis is a specific medical term given to an illness or syndrome by health-care providers. When a doctor evaluates someone experiencing psychosis, he or she gathers as much information as possible. This information comes from a detailed psychiatric interview and observations, medical records, additional information from family members, a physical exam, cognitive assessments, lab tests, and other types of evaluations to determine the illness underlying the episode of psychosis (see Chapter 5 on The Initial Evaluation of Psychosis). While gathering information to evaluate a first episode of psychosis, the doctor often comes up with a differential diagnosis. This is a list of the most likely reasons for the syndrome, in this case, psychosis. Doctors generally use a differential diagnosis to list the possible illness underlying any health problem. For example, if you go to the doctor for a fever, the doctor may make a list of possible reasons for the fever, such as a minor nose cold caused by a virus, strep throat caused by bacteria, pneumonia, meningitis, or other infections. To narrow down this list to the most likely diagnosis, the doctor then uses information from the history (asking questions), physical exam, and lab tests. Oftentimes a doctor uses a working diagnosis to guide treatment planning even if he or she has yet to decide on a final diagnosis. It is important for patients and families to recognize that making a specific diagnosis often requires long-term information that often is not fully available when a person first comes in for treatment. Being unsure about the diagnosis is one reason why a differential diagnosis and a working diagnosis are so important. A working diagnosis allows the doctor to begin an effective treatment plan even though a final diagnosis may not yet be clear. Some patients and families may want to get a specific diagnosis and may be skeptical when the doctor cannot yet definitively provide one.
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Dolman, Peter J. "Surgical Exploration of the Orbit." In Surgery of the Eyelid, Lacrimal System, and Orbit. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195340211.003.0025.
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The orbit comprises the globe and optic nerve surrounded by a complex tangle of muscles, nerves, and vessels, all cushioned in pockets of fat. While surgery in the anterior orbit is readily performed, the challenge increases significantly for deeper orbital pathology because the bony walls on four sides and the eyeball and lid structures anteriorly limit both access and visibility. The apex is a particularly difficult area because so many vital structures converge in its narrow confines. The history and physical examination help narrow the differential diagnosis so that appropriate imaging and special investigations may be arranged. The urgency of these diagnostic tests to allow appropriate medical or surgical intervention is partly determined by the speed of symptom onset and by the presence of significant pain or progressive functional impairment such as vision loss or diplopia. Computed tomography (CT) scans are usually readily available and help define the tissue characteristics and location of an orbital lesion. Reformatting allows coronal, sagittal, and 3-D views without repositioning the patient, although a true coronal CT scan may be requested if a distensible varix is suspected. Contrast CT scans may be useful for assessing the vascularity of the lesion but require an evaluation of renal function. Magnetic resonance (MR) scans may characterize certain soft tissue features better, identifying fluid levels and determining whether a lesion involves normal anatomic structures such as the optic nerve, muscle, or lacrimal gland. They are particularly useful in evaluating lesions of the optic nerve and chiasm. Ultrasounds may help to define certain superficial orbital lesions (distinguishing a lymphoma from a pleomorphic adenoma in the lacrimal gland, for example) and are very useful in assessing intraocular pathology. Positron emission tomography (PET) scans may help determine the presence of recurrent malignancy or lymphoma in a previously operated or treated site and whole body evaluation may be helpful for staging lymphomas. A trained neuroradiologist can help interpret a complex image. In general, well-circumscribed, accessible lesions are excised in toto. Poorly defined, infiltrative lesions and those causing tissue destruction (suggestive of malignancy or aggressive inflammation) usually are biopsied, either by needle or with surgery.
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Trinkaus, Erik, Alexandra P. Buzhilova, Maria B. Mednikova, and Maria V. Dobrovolskaya. "The Ages-at-Death and Sexes of the Sunghir Humans." In The People of Sunghir. Oxford University Press, 2014. http://dx.doi.org/10.1093/oso/9780199381050.003.0009.
Full textAbstract:
Assessment of the ages-at-death and the probable sexes of the Sunghir humans provides a baseline for their paleobiological evaluation. The former is particularly important for the comparative analysis of the immature Sunghir 2 and 3 skeletons, given the marked changes in size and shape with development. The latter is more important for the adult Sunghir 1, 5, and 6 remains, given some degree of sexual dimorphism among recent humans and apparently within Late Pleistocene early modern humans. In the assessment of age-at-death, it is necessary to evaluate the remains with reference to chronological scales derived from extant human populations of known age (or very recent historical skeletal samples with documented ages). This consideration applies particularly to changes in fibrocartilaginous articulations with age (in this case, a sternal rib end and an auricular surface of Sunghir 1) and to dental calcification during development (for Sunghir 2 and 3). The majority of the data available for these approaches derives from recent European and European-derived (primarily North American) populations, with occasional cross-references to more limited data on recent populations from elsewhere in the Old World. The one exception to this requirement is dental occlusal attrition, for which very general Late Pleistocene (and preindustrial Holocene) reference samples are appropriate, in all cases using scales that are based either on other methods of skeletal aging or employ some version of the “Miles technique” (sequential assessment of dental wear for postcanine teeth as they come into functional occlusion; Brothwell 1981). The determination of sex is most reliable when it utilizes the pelvis, and there is a series of criteria for pelvic sexual evaluation that appear to be universal among recent humans (Brůžek 2002). These dimorphic features mostly appear during adolescence associated with differential lateral development of the pelvis (Coleman 1969; Lavelle 1995). Dimorphic aspects of the greater sciatic notch may appear prior to puberty (Holcomb and Konigsberg 1995; Scheuer and Black 2000), but tests sexing recent human immature skeletons of known sex have provided poor results and tend to identify males more accurately than females (Cardoso and Saunders 2008; Vlak et al. 2008; Wilson et al. 2008).
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Older, J. Justin. "Clinical Presentation of Eyelid Lesions." In Surgery of the Eyelid, Lacrimal System, and Orbit. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195340211.003.0006.
Full textAbstract:
Appropriate evaluation of an eyelid lesion is necessary before deciding on a course of surgical or nonsurgical treatment. A differential diagnosis is established based on the patient’s history and the physical characteristics of the mass. Many eyelid masses have similar physical and behavioral characteristics. In some cases, radiologic examination can be helpful in determining the extent or even the type of tumor. Certain malignant tumors may look benign or have the appearance of other malignancies. Biopsy is required for the definitive diagnosis. When faced with an eyelid lesion, the physician must first determine whether the lesion is benign or malignant. This determination will then dictate the next direction of diagnostic tests. If a mass has been present for several months to years or if there has been a history of bleeding, malignancy must be considered. Pain is usually not a component of malignancy, but some moderate discomfort may be present. Malignant lesions are usually destructive. The skin may be altered by a mass or ulceration. A malignancy located at the eyelid margin usually results in loss of lashes. Small malignancies may be similar in appearance to early inflammations, but as these malignancies grow, destruction of tissue is usually evident. If malignancy is not suspected, then a decision as to whether the lesion is inflammatory or not should be made. Small inflammatory lesions such as blepharitis may be ulcerative, cause loss of lashes, and simulate eyelid carcinoma. Swelling, redness, and pain are all characteristics of inflammatory masses such as styes or chalazia. Infected glands away from the lid margin can also have these signs. Swelling in the area of the medial canthus could be a lacrimal sac mucocele if there is no evidence of redness, or it could be a lacrimal sac tumor. Benign lesions that are not inflammatory may have swelling but usually not pain. They may be translucent, such as hair follicle cysts. These tumors often transilluminate. They may have a clear fluid that can be easily identified through thin skin, or there may be a yellowish content such as sebaceous material within the cyst. Some benign lesions may be papillomatous or have keratinized ends, such as cutaneous horns.
Conference papers on the topic "Differential Aptitude Tests – Evaluation"
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Palazzo, Fabio G., Joa˜o V. Sparano, Alexandre N. Simos, Isaias Q. Masetti, and Eduardo A. Tannuri. "Evaluation of the Dynamic Behavior of the P50 FPSO System Using Dynasim: Comparison With Experimental Results." In ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37178.
Full textAbstract:
The P50 system is a Floating Production Storage and Offloading System under construction for future operation at Brazil’s Campos Basin, in a water depth of approximately 1200 m. The system is based on a VLCC vessel, moored in DICAS (Differential Compliance Anchoring) system and presents a reasonably large riser porch on the portside for 77 lines. In this paper the dynamic behavior of the offshore system is evaluated using Dynasim, a time-domain simulation code for moored offshore systems, developed by the University of Sa˜o Paulo and Petrobras. Simulations are compared with experimental results. Two kinds of tests were performed: “Calibration” tests were carried out in order to obtain static coefficients of the hull under isolated current and wind loads. “Validation” tests were conducted to evaluate the dynamic behavior under extreme environmental conditions combining current and wave excitation. First and second-order motions were measured as well as mooring line tensions for three different drafts of the ship. A generally good agreement was observed between numerical simulations and experimental results, reassuring the reliability of the numerical code.
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Arroyo, B., J. A. Álvarez, and R. Lacalle. "Analysis of the Small Punch Test Capability to Evaluate the Response of High Strength Steels Facing HIC or SCC." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63502.
Full textAbstract:
This work is about evaluating the behavior facing HIC of high strength steels by means of the Small Punch Test (SPT). It can be considered as a quasi-non-destructive test in comparison to structural integrity analysis of large components. It was developed during the 80’s with the purpose of estimating the embrittlement grade of nuclear components reducing the amount of material employed. During the last years it has been successfully employed in the evaluation of mechanical properties of different materials and creep behavior. Also approximations for the fracture properties estimations have been carried out using this method. Although a reference standard that includes the tensile and fracture parameters estimations by SPT does not exist, a European Code of Practice (CWA 15627:2008) was recently developed. In addition a European standard is in preparation, including the ultimate research and the backup of the most relevant groups. In this work, high strength steels behavior facing stress corrosion cracking (SCC) or hydrogen Embrittlement (HE) processes are analyzed by means of the Small Punch Test (SPT). The evaluation of the response of materials facing environmental damage processes requires a different consideration if cracks are present on the material or not. In a first stage the study carried out tries to analyze the behavior without cracks, using the threshold stress (σscc) parameter. The aforementioned parameter is obtained from slow strain rate tensile tests (SSRT), which involves its own particular disadvantages. Thus the aptitude of the SPT to obtain the threshold stress is studied, evaluating the influence of variables such as the solicitation rate. In the second part of the work, specimen geometry and test conditions are proposed for the SPT, in order to evaluate the susceptibility facing SCC and HE in presence of cracks for the materials studied. In this case, the fracture toughness parameter that describes the crack initiation process (Khe) will be evaluated and validated by conventional tests based on fracture mechanics. The influence of variables, such as test solicitation rate on the results, is analyzed in order to obtain a qualitative methodology to evaluate mechanical-environmental damage processes by SPT means. For the SPT tests carried out, common Small Punch specimens of 10×10 mm of section and 0,5 mm of thickness are used for σscc determination.
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Hørte, Torfinn, Arve Bjørset, Dan Tudor Zaharie, and Sune Pettersen. "Benefit From Structural Reliability Analysis in Risk Evaluation of Collapse of Externally Supported Casing." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18887.
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Abstract Casing collapse capacity was identified by Equinor as a critical operational parameter on one of its fields in production. This led to re-evaluation and detailed studies of the overall well design, specifically the production casing’s collapse capacity, together with consequence and risk evaluations in case of a potential casing failure. As an important and useful input to the risk evaluations, the present paper presents a structural reliability analysis for casing collapse. Initially, the casing collapse capacity was evaluated using API TR 5C3 / ISO 10400 [1], with insufficient capacity being documented. In order to investigate further, physical material testing and collapse testing were performed. Two kinds of collapse tests have been performed: i) tests of unsupported pipe and ii) test of pipes with external support from the cement and formation surrounding the pipe. While a paper from 2018 (OMAE2018-78767) considered casings without external support, the present paper pays attention towards supported pipes. Five collapse tests have been performed where test lengths of the 9 5/8” casing were installed inside a thick-walled pipe that simulates the support. A small gap leaves an annulus between the casing and the supporting pipe, allowing a controlled pressure to increase until collapse. The tests have been simulated by finite element analyses. Good correspondence was obtained, providing confidence that FE simulations can be used to predict the collapse capacity of supported pipes. While the tests were only performed for an idealized case with support around the whole circumference, a large number of FE simulations have been carried out for different combinations of support conditions together with variations in pipe ovality and internal wear from drilling. Ideally, the space between the casing and the rock formation is filled by cement. However, in practice there may be channels where there is no cement, likely to occur if the casing is eccentric in the well bore during cementing. These results from these FE simulations have been used to generate a response surface. Subsequent structural reliability analyses have been performed, in which well specific uncertainty associated with the above parameters is considered. Measurements and logging are used to minimize the uncertainty in these inputs and thereby leading to a reduction in the calculated failure probability. The probability of casing collapse is calculated conditional on different magnitude of the differential pressure of the pipe. By using SRA the potential over-conservatism in the conventional deterministic analysis is avoided. The SRA results were used to assist in the risk evaluation resulting in an allowance for continued production on existing wells.
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Wang, Jing, Noritaka Yusa, Hongliang Pan, Mika Kemppainen, Iikka Virkkunen, and Hidetoshi Hashizume. "Modeling of Thermal Fatigue Crack for Enhancement of Electromagnetic Nondestructive Evaluation of Nuclear Power Plant." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16033.
Full textAbstract:
The present study investigates modeling of thermal fatigue crack by the finite element method from the view point of eddy current testing. Three artificially produced thermal fatigue cracks introduced into Inconel 600 specimens are prepared. Eddy current signals are gathered by a differential type plus point probe with 25 kHz and 100 kHz. Subsequent destructive tests show the profile of these cracks. In the numerical simulation thermal fatigue crack is modeled as a region with constant width, uniform conductivity and real profile. Results of the study combining the previous study on modeling of thermal fatigue crack in type 304 stainless steel specimen reveal that thermal fatigue crack, unlike stress corrosion crack, generally should be modeled as an almost nonconductive region regardless of frequencies. Furthermore the resistance of thermal fatigue crack defined as width divided by conductivity is almost unchanged, even though the appropriate conductivity and width are changing with the frequency.
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Safaei Baghbaderani, Keyvan, Mohammadreza Nematollahi, Parisa Bayatimalayeri, Hediyeh Dabbaghi, Ahmadreza Jahadakbar, and Mohammad Elahinia. "Mechanical Evaluation of Selective Laser Melted Ni-Rich NiTi: Compression, Tension, and Torsion." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8432.
Full textAbstract:
Abstract Two unique behaviors of superelasticity and shape memory effect have made shape memory alloy such as NiTi, an interesting alloy for different applications. Recently, additive manufacturing (AM) as a powerful tool for fabricating NiTi has become of interest to make complex geometries. Selective laser melting (SLM) is an AM method that not only provides flexibility to make complex 3D shapes but also it can be possible to tailor the thermomechanical properties of the parts just by changing the process parameters. The non-homogenous microstructure of as-fabricated parts as well as asymmetric mechanical behavior of NiTi, make it important to study the properties of SLM NiTi parts under different loading condition. In this study, Ni50.8Ti (at. %) powder was utilized to fabricate cube, dog-bone, and tube by SLM technique. The transformation temperatures (TTs) of samples were measured by the differential scanning calorimetry (DSC) method and the variation of TTs was discussed. Three coupons were tested mechanically under compression, tension, and torsion. In-situ digital image correlation (DIC) was employed to measure and monitor the strain field of samples during the mechanical tests. The strain distribution showed localized strain for all three samples. The equivalent stress/strain was calculated to compare the result of compressive, tensile, and torsional responses and the significant asymmetric behavior was shown and discussed.
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Takagi, Yoshio, Hiroyasu Torii, Toshiyuki Sawa, and Yuya Omiya. "Sealing Performance Evaluation of Pipe Flange Connection With Spiral Wound Gasket Under Cyclic Thermal Condition." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77490.
Full textAbstract:
Although a lot of pipe flange connections are exposed to elevated temperature during long-term plant operation, a sealing performance of the pipe flange connections at elevated temperature is not well understood because of the experimental difficulty and the analytical problems which result from the lack of the materials properties of gaskets at elevated temperature. The authors have been evaluating the effects of the material properties of spiral wound gaskets (SWG) and the sealing performance of the pipe flange connections at elevated temperature with numerical and experimental analysis. The gasket stress induced by the mismatch of the thermal expansion between the gasket and flange/bolt increased as increasing the temperature in the case that the thermal expansion coefficient of the gasket was larger than that of bolt/flange material and the sealing performance of the pipe flange connection was improved. However, the thermal expansion coefficient declines at temperatures higher than 210 °C. In addition, the binder compositions of SWG vaporize and the mechanical properties slightly change at high temperature such as higher than 200°C. Therefore, the sealing performance of pipe flange connection with SWG might decline more than 200°C. The sealing performance and long-term durability of pipe flange connection with SWG at elevated temperature were evaluated in this study. The long term leakage test with heat cycle revealed that the sealing performance of pipe flange connection didn’t show any degradation for 21 days. The compression tests for the new, the thermal aged and the used gaskets were done to investigate the effect of material characteristics on the long term sealing performance. In addition to the leakage test and the compression tests, the thermal characteristics of SWG were evaluated by the Thermogravimetry/Differential Thermal Analyzer (TG/DTA) measurement. The measurement showed the weight loss of SWG more than 130°C. According to those experimental results and FE analysis, the effect of temperature on the sealing performance was discussed.
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Ih, Jeong-Guon, Su-Won Jang, Cheol-Ho Jeong, Youn-Young Jeung, and Kye-Sup Jun. "A Study on the Sound Quality Evaluation Model of the Air Cleaner." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41115.
Full textAbstract:
In operating the air cleaner for a long time, people in a quiet enclosed space expect calm sound at low operational levels for a routine cleaning of air; in contrast, a powerful, yet not-annoying, sound is expected at high operational levels for an immediate cleaning of pollutants. In this context, it is important to evaluate and design the air cleaner noise to satisfy such contradictory expectation from the customers. In this study, a model for evaluating the air cleaner sound quality was developed based on the objective and subjective analyses. Sound signals from various air cleaners were recorded and they were edited by increasing or decreasing the loudness at three wide specific-loudness bands: 20–400 Hz (0–3.8 Bark), 400–1250 Hz (3.8–10 Bark), 1.25k–12.5k Hz bands (10–22.8 Bark). Subjective tests using the edited sounds were conducted by the semantic differential method (SDM) and the method of successive intervals (MSI). SDM test for 7 adjective pairs was conducted to find the relation between subjective feeling and frequency bands. Two major feelings, performance and annoyance, were factored out from the principal component analysis. We found that the performance feeling was related to both low and high frequency bands; whereas the annoyance feeling was related to high frequency bands. MSI test using the 7 scales was conducted to derive the sound quality index to express the severity of each perceptive descriptor. Annoyance and performance indices of air cleaners were modeled from the subjective responses of the juries and the measured sound quality metrics: loudness, sharpness, roughness, and fluctuation strength. Multiple regression method was employed to generate sound quality evaluation models. Using the developed indices, sound quality of the measured data were evaluated and compared with the subjective data. The difference between predicted and tested scores was less than 0.5 point.
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Giacomelli, Enzo, Massimo Schiavone, Fabio Manfrone, and Andrea Raggi. "Flow Coefficient Evaluation of Poppet Valves Used in Reciprocating Compressors for LDPE." In ASME 2008 Pressure Vessels and Piping Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/pvp2008-61286.
Full textAbstract:
Poppet valves have been used for a long time for very high pressure reciprocating compressors, as for example in the case of Low Density Polyethylene. These applications are very critical because the final pressure can reach 350 MPa and the evaluation of the performance of the machines is strongly connected to the proper operation and performance of the valve itself. The arrangement of cylinders requires generally a certain compactness of valve to withstand high fatigue stresses, but at the same time pressure drop and operating life are very important. In recent years the reliability of the machines has been improving over and over and the customers’ needs are very stringent. Therefore the use of poppet valves has been extended to other cases. In general the mentioned applications are heavy duty services and the simulation of the valves require some coefficients to be used in the differential equations, able to describe the movement of plate/disk or poppet and the flow and related pressure drop through the valves. Such coefficients are often determined in an experimental way in order to have a simulation closer to the real operating conditions. For the flow coefficients it is also possible today to use theoretical programs capable of determining the needed values in a quick and economical way. Some investigations have been carried out to determine the values for certain geometries of poppet valves. The results of the theory have been compared with some experimental tests. The good agreement between the various methods indicates the most suitable procedure to be applied in order to have reliable data. The advantage is evident as the time necessary for the theoretical procedure is faster and less expensive. This is of significant importance at the time of the design and also in case of a need to provide timely technical support for the operating behavior of the valves. Particularly for LDPE, the optimization of all the parameters is strongly necessary. The fatigue stresses of cylinder heads and valve bodies have to match in fact with gas passage turbulence and pressure drop, added to the mechanical behavior of the poppet valve components.
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Gocht, T., W. Kästner, A. Kratzsch, and M. Strasser. "Test and Evaluation of a Filtering System for Retention of Fibres in a Coolant Flow After Loss-of-Coolant Accident." In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-54078.
Full textAbstract:
In case of an accident the safe heat removal from the reactor core with the installed emergency core cooling system (ECCS) is one of the main features in reactor safety. During a loss-of-coolant accident (LOCA) the release of insulation material fragments in the reactor containment can lead to malfunctions of ECCS. Therefore, the retention of particles by strainers or filtering systems in the ECCS is one of the major tasks. The aim of the presented experimental investigations was the evaluation of a filtering system for the retention of fiber-shaped particles in a fluid flow. The filtering system consists of a filter case with a special lamellar filter unit. The tests were carried out at a test facility with filtering units of different mesh sizes. Insulation material (mineral rock wool) was fragmented to fiber-shaped particles. To simulate the distribution of particle concentration at real plants with large volumes the material was divided into single portions and introduced into the loop with a defined time interval. Material was transported to the filter by the fluid and agglomerated there. The assessment of functionality of the filtering system was made by differential pressure between inlet and outlet of the filtering system and by mass of penetrated particles. It can be concluded that for the tested filtering system no penetration of insulation particles occurred.
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Gogoi, Tapan Kr, and Uddipta Gautam. "Performance Evaluation of a Gas and Steam Turbine Based Cogeneration Plant: A Case Study." In ASME 2019 Gas Turbine India Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gtindia2019-2358.
Full textAbstract:
Abstract In this study, performance of a combined power and cogeneration plant is evaluated. The plant is basically the captive power plant (CPP) of Numaligarh Refinery Limited (NRL), located in Golaghat district of Assam, India. The plant consists of a gas turbine (GT) plant as topping and a steam turbine (ST) plant as bottoming cycle. In the CPP, there was also provision for extracting steam from the ST at two different points for process heating in the refinery. CPP operational data regarding pressure, temperature and mass flow rates were collected from the refinery. It was observed that although the performance related data (the GT and ST power outputs) were available but the air flow rate (AFR) of the GT plant was not known. Therefore, this study aimed first at estimating the unknown AFR using an inverse method for which a differential evolution (DE) based optimization algorithm was used. Next, it was attempted to estimate both the AFR and fuel flow rate (FFR) simultaneously assuming that suppose the FFR is also not known. The objective was to find out better combinations of FFR and AFR over the base case corresponding to the single parameter (only AFR) estimation. The performance of the CPP was evaluated with the estimated AFR corresponding to the base case and also with the one of best FFR/AFR combination out of 25 such combinations obtained from simultaneous estimation. For the base case, the overall energy and exergy efficiency of the CPP were found to be 15.39% and 15.37% respectively. However, if the process heating is also taken into consideration, then these efficiencies in cogeneration mode increase to 21.04% and 21.0%. But with the selected best FFR/AFR combination obtained from simultaneous estimation, the overall energy efficiencies of the combined and the cogeneration plant could be improved from 15.39% to 17.68% and from 21.04% to 24.16% respectively. This has also reduced the total plant irreversibility from 183.729 MW to 152.955 MW. It was found that the maximum exergy destruction occurs in the combustion chamber (58.62%) of the GT plant followed by the utility boiler (29.37%) and heat recovery steam generator (3.76%). The results confirmed lower efficiencies for the plant indicating opportunities for further performance improvement particularly in the GT plant. NRL must go for other performance diagnostic tests which might give some actionable recommendations for restoring the lost performance. In the conclusions, other possible causes of low performances are discussed and necessary recommendations have been provided.