Relevant bibliographies by topics / Nominal Response Model (NRM)

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers
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Academic literature on the topic 'Nominal Response Model (NRM)'

Author: Grafiati
Published: 4 June 2021
Last updated: 13 February 2022

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Journal articles on the topic "Nominal Response Model (NRM)"

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Zu, Jiyun, and Patrick C. Kyllonen. "Nominal Response Model Is Useful for Scoring Multiple-Choice Situational Judgment Tests." Organizational Research Methods 23, no. 2 (November 25, 2018): 342–66. http://dx.doi.org/10.1177/1094428118812669.

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We evaluated the use of the nominal response model (NRM) to score multiple-choice (also known as “select the best option”) situational judgment tests (SJTs). Using data from two large studies, we compared the reliability and correlations of NRM scores with those from various classical and item response theory (IRT) scoring methods. The SJTs measured emotional management (Study 1) and teamwork and collaboration (Study 2). In Study 1 the NRM scoring method was shown to be superior in reliability and in yielding higher correlations with external measures to three classical test theory–based and four other IRT-based methods. In Study 2, only slight differences between scoring methods were observed. An explanation for the discrepancy in findings is that in cases where item keys are ambiguous (as in Study 1), the NRM accommodates that ambiguity, but in cases where item keys are clear (as in Study 2), different methods provide interchangeable scores. We characterize ambiguous and clear keys using category response curves based on parameter estimates of the NRM and discuss the relationships between our findings and those from the wisdom-of-the-crowd literature.
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García-Pérez, Miguel A. "Order-Constrained Estimation of Nominal Response Model Parameters to Assess the Empirical Order of Categories." Educational and Psychological Measurement 78, no. 5 (June 19, 2017): 826–56. http://dx.doi.org/10.1177/0013164417714296.

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Bock’s nominal response model (NRM) is sometimes used to identify the empirical order of response categories in polytomous items but its application tags many items as having disordered categories. Disorderly estimated categories may not reflect a true characteristic of the items but, rather, a numerically best-fitting solution possibly equivalent to other solutions with orderly estimated categories. To investigate this possibility, an order-constrained variant of the NRM was developed that enforces the preassumed order of categories on parameter estimates, for a comparison of its outcomes with those of the original unconstrained NRM. For items with ordered categories, order-constrained and unconstrained solutions should account for the data equally well even if the latter solution estimated disordered categories for some items; for items with truly disordered categories, the unconstrained solution should outperform the order-constrained solution. Criteria for this comparative analysis are defined and their utility is tested in several simulation studies with items of diverse characteristics, including ordered and disordered categories. The results demonstrate that a comparison of order-constrained and unconstrained calibrations on such criteria provides the evidence needed to determine whether category disorder estimated on some items by the original unconstrained form of the NRM is authentic or spurious. Applications of this method to assess category order in existing data sets are presented and practical implications are discussed.
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Matlock, Ki Lynn, Ronna C. Turner, and W. Dent Gitchel. "A Study of Reverse-Worded Matched Item Pairs Using the Generalized Partial Credit and Nominal Response Models." Educational and Psychological Measurement 78, no. 1 (October 6, 2016): 103–27. http://dx.doi.org/10.1177/0013164416670211.

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The generalized partial credit model (GPCM) is often used for polytomous data; however, the nominal response model (NRM) allows for the investigation of how adjacent categories may discriminate differently when items are positively or negatively worded. Ten items from three different self-reported scales were used (anxiety, depression, and perceived stress), and authors wrote an additional item worded in the opposite direction to pair with each original item. Sets of the original and reverse-worded items were administered, and responses were analyzed using the two models. The NRM fit significantly better than the GPCM, and it was able to detect category responses that may not function well. Positively worded items tended to be more discriminating than negatively worded items. For the depression scale, category boundary locations tended to have a larger range for the positively worded items than for the negatively worded items from both models. Some pairs of items functioned comparably when reverse-worded, but others did not. If an examinee responds in an extreme category to an item, the same examinee is not necessarily likely to respond in an extreme category at the opposite end of the rating scale to a similar item worded in the opposite direction. Results of this study may support the use of scales composed of items worded in the same direction, and particularly in the positive direction.
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Harel, Daphna, and Russell J. Steele. "An Information Matrix Test for the Collapsing of Categories Under the Partial Credit Model." Journal of Educational and Behavioral Statistics 43, no. 6 (July 16, 2018): 721–50. http://dx.doi.org/10.3102/1076998618787478.

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Collapsing categories is a commonly used data reduction technique; however, to date there do not exist principled methods to determine whether collapsing categories is appropriate in practice. With ordinal responses under the partial credit model, when collapsing categories, the true model for the collapsed data is no longer a partial credit model, and therefore refitting a partial credit model may result in model misspecification. This article details the implementation and performance of an information matrix test (IMT) to assess the implications of collapsing categories for a given data set under the partial credit model and compares its performance to the application of a nominal response model (NRM) and the S − X2 goodness-of-fit statistic. The IMT and NRM-based test are able to correctly determine the true number of categories for an item, given reasonable power through this goodness-of-fit test. We conclude by applying the test to a well-studied data set from the literature.
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Jefmański, Bartłomiej, and Adam Sagan. "Item Response Theory Models for the Fuzzy TOPSIS in the Analysis of Survey Data." Symmetry 13, no. 2 (January 29, 2021): 223. http://dx.doi.org/10.3390/sym13020223.

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The fuzzy TOPSIS (The Technique for Order of Preference by Similarity to Ideal Solution) is an attractive tool for measuring complex phenomena based on uncertain data. The original version of the method assumes that the object assessments in terms of the adopted criteria are expressed as triangular fuzzy numbers. One of the crucial stages of the fuzzy TOPSIS is selecting the fuzzy conversion scale, which is used to evaluate objects in terms of the adopted criteria. The choice of a fuzzy conversion scale may influence the results of the fuzzy TOPSIS. There is no uniform approach in constructing and selecting the fuzzy conversion scale for the fuzzy TOPSIS. The choice is subjective and made by researchers. Therefore, the aim of the article is to present a new, objective approach to the construction of fuzzy conversion scales based on Item Response Theory (IRT) models. The following models were used in the construction of fuzzy conversion scales: Polychoric Correlation Model (PM), Polytomous Rasch Model (PRM), Rating Scale Model (RSM), Partial Credit Model (PCM), Generalized Partial Credit Model (GPCM), Graded Response Model (GRM), Nominal Response Model (NRM). The usefulness of the proposed approach is presented on the example of the analysis of a survey’s results on measuring the quality of professional life of inhabitants of selected communes in Poland. The obtained results indicate that the choice of the fuzzy conversion scale has a large impact on the closeness coefficient values. A large difference was also observed in the spreads of triangular fuzzy numbers between scales based on IRT models and those used in the literature on the subject. The use of the fuzzy TOPSIS with fuzzy conversion scales built based on PRM, RSM, PCM, GPCM, and GRM models gives results with a greater range of variability than in the case of fuzzy conversion scales used in empirical research.
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Percival, Mary-Elizabeth M., Hai-Lin Wang, Mei-Jie Zhang, Elihu H. Estey, Mark Litzow, Partow Kebriaei, Marcos de Lima, Wael Saber, Daniel J. Weisdorf, and Brenda M. Sandmaier. "Impact of Depth of Pretransplant Clinical Response on Outcomes of Acute Myeloid Leukemia Patients in First Complete Remission (AML-CR1) Who Undergo Allogeneic Hematopoietic Cell Transplantation (AlloHCT)." Blood 134, Supplement_1 (November 13, 2019): 4585. http://dx.doi.org/10.1182/blood-2019-123510.

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Introduction: AML patients with intermediate or high-risk features often undergo allogeneic hematopoietic cell transplantation (alloHCT) during first complete remission (CR). The 2017 European LeukemiaNet guidelines for AML specify categories of CR: both with and without count recovery (CR vs. CRi) and with and without measurable residual disease (MRD). Previous smaller retrospective studies have suggested poorer survival outcomes after alloHCT for patients with responses less than CR. Methods: Eligible cases were determined using the CIBMTR registry. Each had AML in CR1, was ≥ 18 years, and underwent alloHCT between January 1, 2007 and December 31, 2015. MRD was defined based on the answers to qualitative questions on standard clinical reporting forms that ask if the patient is in either molecular or cytogenetic remission and if disease is detected in marrow by flow cytometry at time of HCT. The primary outcome was overall survival (OS), and secondary outcomes were non-relapse mortality (NRM), relapse and disease-free survival (DFS). The Kaplan-Meier method was used to estimate survival and cumulative incidence function was used to estimate relapse and NRM. Multivariable analysis (MVA) was performed using the Cox proportional hazards model to adjust for patient-, disease-, and transplant-related factors. Adjusted probabilities of DFS and OS, adjusted cumulative incidence curves of NRM and relapse were generated from final Cox regression models stratified on CR vs. CRi and weighted averages of covariate values using pooled sample proportion as weight function. Results: We identified 2492 cases (CR, n=1799; CRi, n=693). The main effect variable (CR vs. CRi) was missing in 262 additional patients; these patients were excluded when univariate analysis confirmed no significant associations, suggesting a random distribution of missing data. Patient characteristics are summarized in Table 1. Compared with patients with CR, patients with CRi were more likely to have a Karnofsky score <90 (38% vs. 31%) and an HCT-CI score 3+ (47% vs. 40%). Other variables were well matched between the groups. MVA demonstrated significantly increased likelihood of mortality in patients with CRi compared to those with CR with hazard ratio (HR) 1.27; 95% confidence interval (CI) (1.13-1.43) (Figure 1A). Other covariates significantly associated with shorter OS included older age, poor-risk cytogenetics, lower Karnofsky score, higher HCT-CI score, and higher white blood cell count at diagnosis. The adjusted OS probabilities at 5 year post-HCT accounted for factors from MVA model are 50% (95%CI 47-52) for patients with CR and 43% (95%CI 39-47) for patients with CRi. CRi was also associated with significantly increased NRM [HR 1.33, 95%CI(1.11-1.59)] with only a trend in increased relapse [HR 1.15, 95% CI(0.99-1.34), p=0.07] resulting in inferior DFS [HR 1.20, 95%CI(1.07-1.35)]. MRD status was available in a subset of 2297 patients, and pairwise comparison demonstrated that presence of MRD was associated with shorter OS, shorter DFS, higher NRM, and increased relapse compared to absence of MRD (Figure 1B). Pairwise interaction between the main effects (CR vs. CRi) and MRD status were tested with no significant findings at a level of 0.01, demonstrating that the effects of incomplete count recovery and MRD are independent of each other. Conclusions: Analysis of this large CIBMTR cohort demonstrates that survival outcomes differ among AML patients nominally in CR at the time of alloHCT. Patients with CRi and/or MRD have significantly shorter OS after alloHCT compared to those in CR, as well as shorter DFS and higher NRM. Further studies should focus on limiting NRM and reducing relapse to optimize post-alloHCT outcomes for patients with responses less than CR. Disclosures Percival: Pfizer Inc.: Research Funding; Nohla Therapeutics: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees. Kebriaei:Jazz: Consultancy; Pfizer: Honoraria; Amgen: Research Funding; Kite: Honoraria. Weisdorf:Fate Therapeutics: Consultancy; Incyte: Research Funding; Pharmacyclics: Consultancy.
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Storme, Martin, Nils Myszkowski, Simon Baron, and David Bernard. "Same Test, Better Scores: Boosting the Reliability of Short Online Intelligence Recruitment Tests with Nested Logit Item Response Theory Models." Journal of Intelligence 7, no. 3 (July 10, 2019): 17. http://dx.doi.org/10.3390/jintelligence7030017.

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Assessing job applicants’ general mental ability online poses psychometric challenges due to the necessity of having brief but accurate tests. Recent research (Myszkowski & Storme, 2018) suggests that recovering distractor information through Nested Logit Models (NLM; Suh & Bolt, 2010) increases the reliability of ability estimates in reasoning matrix-type tests. In the present research, we extended this result to a different context (online intelligence testing for recruitment) and in a larger sample ( N = 2949 job applicants). We found that the NLMs outperformed the Nominal Response Model (Bock, 1970) and provided significant reliability gains compared with their binary logistic counterparts. In line with previous research, the gain in reliability was especially obtained at low ability levels. Implications and practical recommendations are discussed.
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Battauz, Michela. "Regularized Estimation of the Nominal Response Model." Multivariate Behavioral Research 55, no. 6 (November 4, 2019): 811–24. http://dx.doi.org/10.1080/00273171.2019.1681252.

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Revuelta, Javier. "Multidimensional Item Response Model for Nominal Variables." Applied Psychological Measurement 38, no. 7 (June 17, 2014): 549–62. http://dx.doi.org/10.1177/0146621614536272.

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Baker, Frank B. "Equating Tests Under The Nominal Response Model." Applied Psychological Measurement 17, no. 3 (September 1993): 239–51. http://dx.doi.org/10.1177/014662169301700305.

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Dissertations / Theses on the topic "Nominal Response Model (NRM)"

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Stokes, Steven Scott. "An Examination of the Psychometric Properties of the Trauma Inventory for Partners of Sex Addicts (TIPSA)." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6500.

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This study examined the psychometric properties of the Trauma Inventory for Partners of Sex Addicts (TIPSA). Using the Nominal Response Model (NRM), I examined several aspects of item and option functioning including discrimination, empirical category ordering, and information. Category Boundary Discrimination (CBD) parameters were calculated to determine the extent to which respondents distinguished between adjacent categories. Indistinguishable categories were collapsed through recoding. Empirically disordered response categories were also collapsed through recoding. Findings revealed that recoding solved some technical functioning issues in some items, and also revealed items (and perhaps option anchors) that were probably poorly conceived initially. In addition, nuisance or error variance was reduced only marginally by recoding, and the relative standing of respondents on the trait continuum remained largely unchanged. Items in need of modification or removal were identified, and issues of content validity were discussed.
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Chauhan, Arjun. "Modeling and Predicting Taxi Times at Airports." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3472.

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This research aims at providing methods in analyzing and estimating the taxi times of aircraft at airports, which are expected to be an important element for reducing taxiing delay and consequent excess fuel consumption and environmental costs. The proposed model involves a set of regression equations to model the taxi-out and taxi-in times at airports. The estimated results can be used to calculate the nominal taxi times, which are essential measures for evaluating the taxiing delays at airports. Given the outcomes of the regression model, an iterative algorithm is developed to predict taxi times. A case study at LGA shows that the proposed algorithm demonstrates higher accuracy in comparison to other algorithms in existing literature.
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Moulton, Sara E. "An Examination of the Psychometric Properties of the Student Risk Screening Scale for Internalizing and Externalizing Behaviors: An Item Response Theory Approach." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6604.

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This research study examined the psychometric properties of the Student Risk Screening Scale for Internalizing and Externalizing Behaviors (SRSS-IE) using Item Response Theory (IRT) methods among a sample of 2,122 middle school students. The SRSS-IE is a recently revised screening instrument aimed at identifying students who are potentially at risk for emotional and behavioral disorders (EBD). There are two studies included in this research. Study 1 utilized the Nominal Response and Generalized Partial Credit models of IRT to evaluate items from the SRSS-IE in terms of the degree to which the response options for each item functioned as intended by the scale developers and how well those response options discriminated among students who exhibited varying levels of EBD risk. Results from this first study indicated that the four response option configurations of the items on the SRSS-IE may not adequately discriminate among the frequency of externalizing and internalizing behaviors demonstrated by middle school students. Recommendations for item response option revisions or scale scoring revisions are discussed in this study. In study 2, differential item functioning (DIF) and differential step functioning (DSF) methods were used to examine differences in item and response option functioning according to student gender variables. Additionally, test information functions (TIFs) were used to determine whether preliminary recommendations for cut scores differ by gender. Results of this second study indicate that two of the items on the SRSS-IE systematically favor males over females and one item systematically favors females over males. Additionally, examination of TIFs demonstrated different degrees of measurement precision at various levels of theta for males and females on both the externalizing and internalizing constructs. Implications of these results are discussed in relation to possible revisions of the SRSS-IE items, cut scores, or scale scoring procedures.
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Cook, Robert Joseph. "Application of item response theory models to the algorithmic detection of shift errors on paper and pencil tests." 2013. https://scholarworks.umass.edu/dissertations/AAI3603070.

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On paper and pencil multiple choice tests, the potential for examinees to mark their answers in incorrect locations presents a serious threat to the validity of test score interpretations. When an examinee skips one or more items (i.e., answers out of sequence) but fails to accurately reflect the size of that skip on their answer sheet, that can trigger a string of misaligned responses called shift errors. Shift errors can result in correct answers being marked as incorrect, leading to possible underestimation of an examinee's true ability. Despite movement toward computerized testing in recent years, paper and pencil multiple choice tests are still pervasive in many high stakes assessment settings, including K 12 testing (e.g., MCAS) and college entrance exams (e.g., SAT), leaving a continuing need to address issues that arise within this format. Techniques for detecting aberrant response patterns are well established but do little to recognize reasons for the aberrance, limiting options for addressing the misfitting patterns. While some work has been done to detect and address specific forms of aberrant response behavior, little has been done in the area of shift error detection, leaving great room for improvement in addressing this source of aberrance. The opportunity to accurately detect construct irrelevant errors and either adjust scores to more accurately reflect examinee ability or flag examinees with inaccurate scores for removal from the dataset and retesting would improve the validity of important decisions based on test scores, and could positively impact model fit by allowing for more accurate item parameter and ability estimation. The purpose of this study is to investigate new algorithms for shift error detection that employ IRT models for probabilistic determination as to whether misfitting patterns are likely to be shift errors. The study examines a matrix of detection algorithms, probabilistic models, and person parameter methods, testing combinations of these factors for their selectivity (i.e., true positives vs. false positives), sensitivity (i.e., true shift errors detected vs. undetected), and robustness to parameter bias, all under a carefully manipulated, multifaceted simulation environment. This investigation attempts to provide answers to the following questions, applicable across detection methods, bias reduction procedures, shift conditions, and ability levels, but stated generally as: 1) How sensitively and selectively can an IRT based probabilistic model detect shift error across the full range of probabilities under specific conditions?, 2) How robust is each detection method to the parameter bias introduced by shift error?, 3) How well does the detection method detect shift errors compared to other, more general, indices of person fit?, 4) What is the impact on bias of making proposed corrections to detected shift errors?, and 4) To what extent does shift error, as detected by the method, occur within an empirical data set? Results show that the proposed methods can indeed detect shift errors at reasonably high detection rates with only a minimal number of false positives, that detection improves when detecting longer shift errors, and that examinee ability is a huge determinant factor in the effectiveness of the shift error detection techniques. Though some detection ability is lost to person parameter bias, when detecting all but the shortest shift errors, this loss is minimal. Application to empirical data also proved effective, though some discrepancies in projected total counts suggest that refinements in the technique are required. Use of a person fit statistic to detect examinees with shift errors was shown to be completely ineffective, underscoring the value of shift error specific detection methods.
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Arias, De Los Santos Angel Manuel. "Building a validity argument for the listening component of the Test de connaissance du français in the context of Quebec immigration." Thèse, 2018. http://hdl.handle.net/1866/21211.

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Book chapters on the topic "Nominal Response Model (NRM)"

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Bock, R. Darrell. "The Nominal Categories Model." In Handbook of Modern Item Response Theory, 33–49. New York, NY: Springer New York, 1997. http://dx.doi.org/10.1007/978-1-4757-2691-6_2.

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Choi, Hye-Jeong, Allan S. Cohen, and Brian A. Bottge. "An Application of a Random Mixture Nominal Item Response Model for Investigating Instruction Effects." In Quantitative Psychology Research, 39–48. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-38759-8_4.

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"Detecting Faulty Within-Item Category Functioning With the Nominal Response Model." In Handbook of Item Response Theory Modeling, 404–23. Routledge, 2014. http://dx.doi.org/10.4324/9781315736013-29.

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Conference papers on the topic "Nominal Response Model (NRM)"

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Yang, M. T., and J. H. Griffin. "A Reduced Order Model of Mistuning Using a Subset of Nominal System Modes." In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-288.

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Reduced order models have been reported in the literature that can be used to predict the harmonic response of mistuned bladed disks. It has been shown that in many cases they exhibit structural fidelity comparable to a finite element analysis of the full bladed disk system while offering a significant improvement in computational efficiency. In these models the blades and disk are treated as distinct substructures. This paper presents a new, simpler approach for developing reduced order models in which the modes of the mistuned system are represented in terms of a sub-set of nominal system modes. It has the following attributes: the input requirements are relatively easy to generate; it accurately predicts mistuning effects in regions where frequency veering occurs; as the number of degrees of freedom increases it converges to the exact solution; it accurately predicts stresses as well as displacements; and it accurately models the deformation and stresses at the blades’ bases.
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Gutierrez, Mauricio, Paul Petrie-Repar, Robert E. Kielb, and Nicole L. Key. "A Mistuned Forced Response Analysis of an Embedded Compressor Blisk Using a Reduced Order Model." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76455.

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Accuracy when assessing mistuned forced response analyses is still a mayor concern. Since a full coupled analysis is still very computational expensive, several simplifications and reduced order models are carried out. The use of a reduction method, the assumptions and simplifications, generate different uncertainties that challenge the accuracy in the results. Experimental data are needed for validation and also to understand the propagation of these uncertainties. This paper shows a detailed mistuned forced response analysis of a compressor blisk. The blisk belongs to the Purdue Three-Stage (P3S) Compressor Research Facility. Two different stator-rotor-stator configurations of 38 and 44 upstream stator vanes are taken into consideration. Several loading conditions are analyzed at three different speed lines. A reduced order model known as subset nominal mode (SNM), has been used for all the analyses. This reduction takes as a basis a set of modes within a selected frequency spectrum. A detailed comparison between the predicted and measured results have been performed, showing a good agreement for the high loading conditions.
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Li, Zhen, Qiang Gao, Liangmo Wang, and Jun Tang. "In-Plane Dynamic Response Analysis of Hexagonal and Reentrant Honeycombs Under Uniaxial Impact Loading." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-68134.

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To investigate their in-plane dynamic response, a rigid plate with mass was given an initial velocity to impact (square) honeycombs in the X1 and X2 directions, respectively. Firstly, the impact model was built and validated. Then, impact resistance capacity research was conducted. Results showed that each honeycomb performed similarly in X1 and X2 directions, and the reentrant honeycomb usually used smaller displacement and time to absorb the same amount of kinetic energy. Thus, it is better for application if these factors were the main concerns. After that, the nominal stress at the proximal and distal ends were discussed under various impact velocities. It is shown that, under impact loading, the reentrant honeycomb generally showed higher initial peak stress as well as lower plateau stress at both proximal and distal ends. In addition, combining these with the deformation process of honeycombs, it was concluded that the formation of the plateau area of the nominal stress curve is related to the crushing displacement of the impact plate as well as the collapse of cells.
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Tyapin, Ilya, Marcus Sandberg, Michael Kokkolaras, Anders Lundbladh, and Ola Isaksson. "Jet Engine Design Optimization Using a Knowledge-Based Master Model." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69309.

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This paper presents a preliminary design optimization study of a jet engine structure using a knowledge-based master modeling approach. The objective function is derived based on input-output relationships of a cost-performance model, where specific fuel consumption, pressure loss and direct cost are considered. The advantage of this problem formulation is that it entails a single composite objective function that takes into account mass, structural characteristics, dynamic response and translates them to a direct operational cost function to be minimized. A fan-blade-off scenario is considered as the loading case in this paper. The loss of one fan blade during nominal operation causes a rotor imbalance and structural deformation.
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Hwang, Janghwan, and Sangseok Yu. "Robust Control of Hydrogen Flow for an Automotive Fuel Cell System via Model Reference Adaptive Control." In ASME 2019 13th International Conference on Energy Sustainability collocated with the ASME 2019 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/es2019-3882.

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Abstract Efficient hydrogen flow control is of great importance to ensure the reliable operation of an automotive fuel cell system because it is closely associated with the safety and the economic efficiency. In this study, an effective hydrogen flow control algorithm for hydrogen excess ratio control is addressed by pointing out the recovery speed and overshoot response. Unlike previous studies on the hydrogen management systems of an automotive fuel cell, this study presents an analytic hydrogen tank model which can present the characteristics of the discharge and charge of hydrogen from a type 4 hydrogen tank. To this end, a mode reference adaptive control (MRAC) based on proportional-integral (PI) control is introduced, to ensure robust hydrogen flow during the dynamic operation of fuel cell system. The MRAC was compared with the nominal PI control and PWM control in the hydrogen management system of an automotive fuel cell operating within normal conditions, under steady-state responses and transient. Based on these result, it can further demonstrate that the MRAC algorithm shows better recovery speed and tracking performance than the nominal PI, and PWM control algorithm with respect to the transient behaviors.
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Kenyon, J. A., J. H. Griffin, and N. E. Kim. "Sensitivity of Tuned Bladed Disk Response to Frequency Veering." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53280.

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A continuous method is presented for representing the mode interaction that occurs in frequency veering in terms of the nominal sector modes of a cyclic symmetric bladed disk model constrained at a fixed reference interblade phase angle. Using this method, the effect of frequency veering on the mode shapes can be considered in the context of the generalized forces exciting the system and the modal response of the bladed disk. It is shown that in a blade-dominated family of modes, the transfer of modal energy to the disk in the veering results in a lower generalized force exciting the mode as well as reduced response amplitude in the blade. For the disk-dominated modes, the sharing of modal energy with the blades can lead to the disk being excited by aerodynamic loading. These effects can have important implications for predicting and interpreting forced response in bladed disks. Numerical examples are provided to illustrate these concepts.
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Kaszynski, Alexander A., Joseph A. Beck, and Jeffrey M. Brown. "Experimental Validation of a Mesh Quality Optimized Morphed Geometric Mistuning Model." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43150.

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High cycle fatigue due to mode localization caused by geometric and material mistuning is one of the leading failure risks of integrally bladed rotors (IBRs). Due to the computational analysis cost of full wheel models, IBR mistuned response amplifications are often modeled with reduced order models (ROMs). However, many developed ROMs are based on nominal mode assumptions that do not consider mode shape variations that have been shown to impact predicted mistuned response. Geometrically mistuned finite element models (FEMs) do account for mode shape variations but are notoriously difficult to construct and analyze. Recent advancements in optical scanning have enabled the rapid acquisition of highly accurate dense point clouds representative of manufactured hardware. Previous research pioneered a novel method to automatically and robustly construct an FEM directly from tessellated scan data, this research adds new mesh quality verification algorithms and experimentally validates this algorithm using results from traveling wave excitation. Sensitivity to mesh and point cloud density are also assessed to determine a best practice for creation of the as manufactured mistuned rotor model.
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Joshua, Raymond R., and Douglas E. Adams. "Experimental Identification of Linear and Nonlinear Dynamic Characteristics of a Foam Aircraft Model for Morphing Applications." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14116.

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The genesis of so-called morphing aircraft has been mandated by the need for an expanded flight envelope to fulfill a variety of flight objectives. In order to address the need for expanded flight envelopes, researchers must consider the possibility of dynamic instability due to morphing associated with complex aero-structural interactions during design, development, and flight. The linear and nonlinear dynamic response characteristics of a model aircraft structure are examined in this paper. To identify the linear modal characteristics, impact testing was conducted and the nominal frequency response functions were extracted. Nonlinear characteristics are identified using time-frequency, restoring force, and higher-order frequency response analysis of swept sine response data. The scale-model aircraft with reconfigurable pre-stressed components exhibits strong nonlinearity in the 20-40 Hz frequency range. A cubic stiffness nonlinearity is identified in one portion of the aircraft. In the 40-60 Hz frequency range, stiffness nonlinearities dominate and damping characteristics are primarily linear in nature. Effective characterization of the nonlinearity is a prerequisite for efficient reduced-order models that accurately predict dynamic instability.
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El Genk, Mohamed S., Timothy Schriener, Ragai Altamimi, Andrew Hahn, Christopher Lamb, and Raymond Fasano. "NICSim: Nuclear Instrumentation and Control Simulation for Evaluating Response to Cyber-Attacks." In 2020 International Conference on Nuclear Engineering collocated with the ASME 2020 Power Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icone2020-16756.

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Abstract Digital Instrumentation and Control (I&C) systems in critical energy infrastructure, including nuclear power plants, raise cybersecurity concerns. Cyber-attack campaigns have targeted digital Programmable Logic Controllers (PLCs) used for monitoring and autonomous control. This paper describes the Nuclear Instrumentation and Control Simulation (NICSim) platform for emulating PLCs and investigating potential vulnerabilities of the I&C systems in nuclear power plants. It is being developed at the University of New Mexico’s Institute for Space and Nuclear Power Studies (UNM-ISNPS), in collaboration with Sandia National Laboratories (SNL), with high fidelity emulytics and modeling capabilities of a physics-based, dynamic model of a PWR nuclear power plant. The NICSim platform would be linked to the SCEPTRE framework at SNL to emulate the response of the plant digital I&C systems during nominal operation and while under cyber-attack.
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Ganesh, Sneha, Todd Schweisinger, and John R. Wagner. "An Atmospheric Energy Harvester System: Linear Model and Test." In ASME 2018 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/dscc2018-9150.

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Energy harvesters are steadily gaining popularity as a power source for microelectronic circuits, particularly in wireless sensor nodes and autonomous devices. Energy harvesting from small temperature and/or pressure variations, coupled with an appropriate energy storage unit, can generate sufficient electric power to operate low power electronics. Ongoing research in this area seeks to improve the power capacity and conversion efficiencies of such systems. In this project, a phase change vapor based atmospheric energy harvester with an electromechanical power transformer has been developed. An ethyl chloride fluid system converts the pressure generated, in response to nominal environmental changes, into usable electric power through a mechanical driveline-spring unit and attached DC generator. Published numerical results have indicated 9.6 mW power generation capacity over a 24 hour period for a low frequency sinusoidal temperature input with ±1°C variation at standard pressure. A prototype electromechanical unit was fabricated and experimentally tested; 30 mW electric power for a resistance load was recorded using an emulated input corresponding to 50 bidirectional cyclic atmospheric variations (∼175 hour period). Linearized models were derived to help evaluate the system’s transient characteristics and these mathematical results agreed favorably with the experimental behavior.
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Reports on the topic "Nominal Response Model (NRM)"

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Hamann, Franz, Cesar Anzola, Oscar Avila-Montealegre, Juan Carlos Castro-Fernandez, Anderson Grajales-Olarte, Alexander Guarín, Juan C. Mendez-Vizcaino, Juan J. Ospina-Tejeiro, and Mario A. Ramos-Veloza. Monetary Policy Response to a Migration Shock: An Analysis for a Small Open Economy. Banco de la República de Colombia, January 2021. http://dx.doi.org/10.32468/be.1153.

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We develop a small open economy model with nominal rigidities and fragmented labor markets to study the response of the monetary policy to a migration shock. Migrants are characterized by their productivity levels, their restrictions to accumulate capital, as well as by the flexibility of their labor income. Our results show that the monetary policy response depends on the characteristics of migrants and the local labor market. An inflow of low(high)-productivity workers reduces(increases) marginal costs, lowers(raises) inflation expectations and pushes the Central Bank to reduce(increase) the interest rate. The model is calibrated to the Colombian economy and used to analyze a migratory inflow of financially constraint workers from Venezuela into a sector with flexible and low wages.
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