Browsing by Subject "Uncertainty"

Now showing 1 - 5 of 5
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    Distributed Nonlinear Model Predictive Control for Heterogeneous Vehicle Platoons Under Uncertainty
    (IEEE Xplore, 2021-09) Shen, Dan; Yin, Jianhua; Du, Xiaoping; Li, Lingxi; Electrical and Computer Engineering, School of Engineering and Technology
    This paper presents a novel distributed nonlinear model predictive control (DNMPC) for minimizing velocity tracking and spacing errors in heterogeneous vehicle platoon under uncertainty. The vehicle longitudinal dynamics and information flow in the platoon are established and analyzed. The algorithm of DNMPC with robustness and reliability considerations at each vehicle (or node) is developed based on the leading vehicle and reference information from nodes in its neighboring set. Together with the physical constraints on the control input, the nonlinear constraints on vehicle longitudinal dynamics, the terminal constraints on states, and the reliability constraints on both input and output, the objective function is defined to optimize the control accuracy and efficiency by penalizing the tracking errors between the predicted outputs and desirable outputs of the same node and neighboring nodes, respectively. Meanwhile, the robust design optimization model also minimizes the expected quality loss which consists of the mean and standard deviation of node inputs and outputs. The simulation results also demonstrate the accuracy and effectiveness of the proposed approach under two different traffic scenarios.
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    Patients’ views on variants of uncertain significance across indications
    (Springer, 2019-08-20) Clift, Kristin; Macklin, Sarah; Halverson, Colin; McCormick, Jennifer B.; Abu Dabrh, Abd Moain; Hines, Stephanie; Medicine, School of Medicine
    As genomic sequencing expands into more areas of patient care, an increasing number of patients learn of the variants of uncertain significance (VUSs) that they carry. Understanding the potential psychosocial consequences of the disclosure of a VUS can help inform pre- and post-test counseling discussions. Medical uncertainty in general elicits a variety of responses from patients, particularly in the growing field of medical genetics and genomics. It is important to consider patients’ responses to the ambiguous nature of VUSs across different indications and situational contexts. Genetic counselors and other providers ordering genetic testing should be prepared for the possibility of their patients’ misinterpretation of such results. Pre-test counseling should include a discussion of the possibility of VUSs and what it would mean for the patient’s care and its potential psychosocial impacts. When a VUS is found, post-test counseling should include additional education and a discussion of the variant’s implications and medical management recommendations based on the results. These discussions may help temper subjective interpretations, unrealistic views, and decisional regret.
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    A Psychometric Evaluation of Script Concordance Tests for Measuring Clinical Reasoning
    (2014-01-29) Wilson, Adam Benjamin; Pike, Gary R. (Gary Robert), 1952-; Humbert, Aloysius J.; Brokaw, James J.; Seifert, Mark F.
    Purpose: Script concordance tests (SCTs) are assessments purported to measure clinical data interpretation. The aims of this research were to (1) test the psychometric properties of SCT items, (2) directly examine the construct validity of SCTs, and (3) explore the concurrent validity of six SCT scoring methods while also considering validity at the item difficulty and item type levels. Methods: SCT scores from a problem solving SCT (SCT-PS; n=522) and emergency medicine SCT (SCT-EM; n=1040) were used to investigate the aims of this research. An item analysis was conducted to optimize the SCT datasets, to categorize items into levels of difficulty and type, and to test for gender biases. A confirmatory factor analysis tested whether SCT scores conformed to a theorized unidimensional factor structure. Exploratory factor analyses examined the effects of six SCT scoring methods on construct validity. The concurrent validity of each scoring method was also tested via a one-way multivariate analysis of variance (MANOVA) and Pearson’s product moment correlations. Repeated measures analysis of variance (ANOVA) and one-way ANOVA tested the discriminatory power of the SCTs according to item difficulty and type. Results: Item analysis identified no gender biases. A combination of moderate model-fit indices and poor factor loadings from the confirmatory factor analysis suggested that the SCTs under investigation did not conform to a unidimensional factor structure. Exploratory factor analyses of six different scoring methods repeatedly revealed weak factor loadings, and extracted factors consistently explained only a small portion of the total variance. Results of the concurrent validity study showed that all six scoring methods discriminated between medical training levels in spite of lower reliability coefficients on 3-point scoring methods. In addition, examinees as MS4s significantly (p<0.001) outperformed their MS2 SCT scores in all difficulty categories. Cross-sectional analysis of SCT-EM data reported significant differences (p<0.001) between experienced EM physicians, EM residents, and MS4s at each level of difficulty. When considering item type, diagnostic and therapeutic items differentiated between all three training levels, while investigational items could not readily distinguish between MS4s and EM residents. Conclusions: The results of this research contest the assertion that SCTs measure a single common construct. These findings raise questions about the latent constructs measured by SCTs and challenge the overall utility of SCT scores. The outcomes of the concurrent validity study provide evidence that multiple scoring methods reasonably differentiate between medical training levels. Concurrent validity was also observed when considering item difficulty and item type.
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    A Qualitative Inquiry into Indonesian Women's Breastfeeding Decision-Making
    (2020-09) Johnson, Nicole Lynn; Matthias, Marianne S.; Brann, Maria; Goering, Elizabeth; Tuman, Jack
    Despite the World Health Organization’s longstanding guidelines encouraging exclusive breastfeeding, less than half of babies are breastfed exclusively in Indonesia, a country experiencing a disproportionately high infant mortality rate believed to be related to inadequate access to clean water and health care. Questions remain concerning women’s decision-making about infant feeding, and we know very little about Indonesian women’s decisions and behaviors regarding breastfeeding. The current research explored Indonesian women’s perceptions about their communication with their support persons as they contemplated the best and most appropriate way to feed their infants. During two trips to Indonesia in 2018, semi-structured qualitative interviews and focus groups were conducted with 84 mothers and 36 breastfeeding support persons including spouses, their infants’ grandmothers, midwives, and lactation consultants on Java, Bali, and Flores Islands. Using the constant comparative method, results revealed infants’ grandmothers and fathers as primary sources of breastfeeding support for mothers. Notably, despite their prominence, grandmothers and fathers were not always perceived to be effective sources of support; rather, mothers often described experiencing support that was unwanted or ineffective. Commonly mothers described a grandmother’s attempted support as being couched in criticism or guided by myths, and a father’s ineffective support as the result of lack of knowledge. Conflict with grandmothers was especially problematic given cultural expectations regarding elders. Findings are discussed in the context of Problematic Integration Theory, a general theory that describes the role of communication in experiencing and managing tensions between expectations and desires. Specifically, findings revealed that breastfeeding challenges fundamentally involve negotiating these dilemmas, which are co-created, exacerbated, transformed, and managed through communication between mothers and their support persons. This study demonstrates the centrality of communication in breastfeeding decision-making, highlights the role of grandmothers and fathers in breastfeeding promotion, and emphasizes the importance of informed social support for new mothers.
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    Time-Domain Data Fusion Using Weighted Evidence and Dempster–Shafer Combination Rule: Application in Object Classification
    (MDPI, 2019-12) Khan, Md Nazmuzzaman; Anwar, Sohel; Mechanical Engineering and Energy, School of Engineering and Technology
    To apply data fusion in time-domain based on Dempster–Shafer (DS) combination rule, an 8-step algorithm with novel entropy function is proposed. The 8-step algorithm is applied to time-domain to achieve the sequential combination of time-domain data. Simulation results showed that this method is successful in capturing the changes (dynamic behavior) in time-domain object classification. This method also showed better anti-disturbing ability and transition property compared to other methods available in the literature. As an example, a convolution neural network (CNN) is trained to classify three different types of weeds. Precision and recall from confusion matrix of the CNN are used to update basic probability assignment (BPA) which captures the classification uncertainty. Real data of classified weeds from a single sensor is used test time-domain data fusion. The proposed method is successful in filtering noise (reduce sudden changes—smoother curves) and fusing conflicting information from the video feed. Performance of the algorithm can be adjusted between robustness and fast-response using a tuning parameter which is number of time-steps(ts).