An Improved Model Free Predictive Current Control for PMSM with Current Prediction Error Variations

Funding Agency: Key Areas of Guangdong Province through the Project “Integration and Industrialization of High Performance, Long Endurance, and Integrated Electric Drive System” (Grant Number: 2019B090910001)Peer reviewedPublisher PD

Optimal Control Strategy Design Based on Dynamic Programming for a Dual-Motor Coupling-Propulsion System

A dual-motor coupling-propulsion electric bus (DMCPEB) is modeled, and its optimal control strategy is studied in this paper. The necessary dynamic features of energy loss for subsystems is modeled. Dynamic programming (DP) technique is applied to find the optimal control strategy including upshift threshold, downshift threshold, and power split ratio between the main motor and auxiliary motor. Improved control rules are extracted from the DP-based control solution, forming near-optimal control strategies. Simulation results demonstrate that a significant improvement in reducing energy loss due to the dual-motor coupling-propulsion system (DMCPS) running is realized without increasing the frequency of the mode switch

Can an evidence-based guideline reminder card improve asthma management in the emergency department?

SummaryObjectiveAsthma is the most common chronic disease in children. Previous studies described significant variations in acute asthma management in children. This study was conducted to examine whether asthma management in the pediatric emergency department (ED) was improved through the use of an evidence-based acute asthma care guideline reminder card.MethodsThe Pediatric Acute Asthma Management Guideline (PAMG) was introduced to the ED of a pediatric tertiary care hospital in Ontario, Canada. Medical charts of 278 retrospective ED visits (January–December 2002) and 154 prospective visits (July 2003–June 2004) were reviewed to assess changes in acute asthma management such as medication treatment, asthma education, and discharge planning. Logistic and linear regressions were used to determine the effect of PAMG on asthma management in the ED. The propensity score method was used to adjust for confounding.ResultsDuring the implementation of PAMG, patients who visited the ED were more likely to receive oral corticosteroids (Adjusted Odds Ratio [AOR] = 2.26, 95% CI: 1.63–3.14, p < 0.0001) and oxygen saturation reassessment before ED discharge (AOR = 2.02, 95% CI: 1.45–2.82, p < 0.0001). They also received 0.23 (95% CI: 0.03–0.44, p = 0.0283) more doses of bronchodilator in the first hour of ED stay. Improvements in asthma education and discharge planning were noted, but the changes were not statistically significant.ConclusionsAfter the implementation of an evidence-based guideline reminder card, medication treatment for acute asthma in the ED was significantly improved; however, asthma education and discharge planning remained unchanged. Future efforts on promoting guideline-based practice in the ED should focus on these components

Examining intra-rater and inter-rater response agreement: A medical chart abstraction study of a community-based asthma care program

<p>Abstract</p> <p>Background</p> <p>To assess the intra- and inter-rater agreement of chart abstractors from multiple sites involved in the evaluation of an Asthma Care Program (ACP).</p> <p>Methods</p> <p>For intra-rater agreement, 110 charts randomly selected from 1,433 patients enrolled in the ACP across eight Ontario communities were re-abstracted by 10 abstractors. For inter-rater agreement, data abstractors reviewed a set of eight fictitious charts. Data abstraction involved information pertaining to six categories: physical assessment, asthma control, spirometry, asthma education, referral visits, and medication side effects. Percentage agreement and the kappa statistic (κ) were used to measure agreement. Sensitivity and specificity estimates were calculated comparing results from all raters against the gold standard.</p> <p>Results</p> <p>Intra-rater re-abstraction yielded an overall kappa of 0.81. Kappa values for the chart abstraction categories were: physical assessment (κ 0.84), asthma control (κ 0.83), spirometry (κ 0.84), asthma education (κ 0.72), referral visits (κ 0.59) and medication side effects (κ 0.51). Inter-rater abstraction of the fictitious charts produced an overall kappa of 0.75, sensitivity of 0.91 and specificity of 0.89. Abstractors demonstrated agreement for physical assessment (κ 0.88, sensitivity and specificity 0.95), asthma control (κ 0.68, sensitivity 0.89, specificity 0.85), referral visits (κ 0.77, sensitivity 0.88, specificity 0.95), and asthma education (κ 0.49, sensitivity 0.87, specificity 0.77).</p> <p>Conclusion</p> <p>Though collected by multiple abstractors, the results show high sensitivity and specificity and substantial to excellent inter- and intra-rater agreement, assuring confidence in the use of chart abstraction for evaluating the ACP.</p

How much do health care providers value a community-based asthma care program? – a survey to collect their opinions on the utilities of and barriers to its uptake

<p>Abstract</p> <p>Background</p> <p>A comprehensive asthma care program (ACP) based on Canadian Asthma Consensus Guidelines was implemented in 8 primary care sites in Ontario, Canada. A survey was distributed to health care providers' (HCPs) to collect their opinions on the utilities of and barriers to the uptake of the ACP.</p> <p>Methods</p> <p>A 39-item self-administered survey was mailed to 184 HCPs and support staff involved in delivering the ACP at the end of implementation. The items were presented in mixed formats with most items requiring responses on a five-point Likert scale. Distributions of responses were analyzed and compared across types of HCPs and sites.</p> <p>Results</p> <p>Of the 184 surveys distributed, 108 (59%) were returned, and of that, 83 were completed by HCPs who had clinical contact with the patients. Overall, 95% of the HCPs considered the ACP useful for improving asthma care management. Most HCPs favored using the asthma care map (72%), believed it decreased uncertainties and variations in patient management (91%), and considered it a convenient and reliable source of information (86%). The most commonly reported barrier was time required to complete the asthma care map. Over half of the HCPs reported challenges to using spirometry, while almost 40% identified barriers to using the asthma action plan.</p> <p>Conclusion</p> <p>Contrary to the notion that physicians believe that guidelines foster cookbook medicine, our study showed that HCPs believed that the ACP offered an effective and reliable approach for enhancing asthma care and management in primary care.</p

An improved model free predictive current control for PMSM with current prediction error variations

The conventional model predictive current control is a model-based control method, and the accuracy of the predicted currents is affected by motor parameters such as flux linkage, inductance, and resistance. To get rid of model parameters dependencies, a model-free predictive current control (MFCC) was proposed before, which can improve the parameter robustness without utilizing any knowledge of the initial motor parameters. However, the stagnant current update detection is one of the main problems that limit the current predictive performance. To solve this problem, a current prediction error model according to the contiguous instant current error variations is proposed to reconstruct the surface-permanent magnet synchronous motor (SPMSM) model in this paper. Afterwards, a novel MFCC method with the online parameter identification is developed. This method takes advantage of mathematical relationships in the current prediction error model, and the motor parameters can be updated within each period to improve prediction accuracy. Simulation and experimental results verify that this proposed MFCC method can significantly reduce the stagnation effect and improve MFCC performance under different parameter disturbances.Published versionThis work was supported in part by the Key Areas of Guangdong Province through the Project ‘‘Integration and Industrialization of High Performance, Long Endurance, and Integrated Electric Drive System’’ under Grant 2019B090910001

The Influence of Ni on Bainite/Martensite Transformation and Mechanical Properties of Deposited Metals Obtained from Metal-Cored Wire

The multi-pass deposited metals were prepared by metal-cored wire with low (2.5 wt%) and high (4.0 wt%) Ni to research the effect of Ni on the bainite/martensite transformation. Results showed that deposited metals exhibited a multiphase structure comprised of bainite, martensite and residual austenite, which is not only explained from SEM/TEM, but also identified and quantified each phase from crystallographic structure through XRD and EBSD. With Ni content increasing, the fraction of martensite increases from 37% to 41%, and that of bainite decreases from 61% to 55% accordingly because 4% Ni element narrows the temperature range of the bainite transformation ~20 &deg;C. The 7.8% residual austenite exhibited block and sheet in the deposited metal with low Ni, while the fraction of residual austenite was 3.26% as a film with high Ni, caused by different transformation mechanisms of bainite and martensite. The tensile strengths of deposited metals were 1042 &plusmn; 10 MPa (2.5% Ni) and 1040 &plusmn; 5 MPa (4% Ni), respectively. The yield strength of deposited metals with high Ni was 685 &plusmn; 18 MPa, which was higher than low Ni due to the high fraction of martensite. The impact values of deposited metals with high Ni content decreased because the volume fraction of bainite and residual austenite and area fraction of large-angle grain boundary were lower

The Influence of Ni on Bainite/Martensite Transformation and Mechanical Properties of Deposited Metals Obtained from Metal-Cored Wire

The multi-pass deposited metals were prepared by metal-cored wire with low (2.5 wt%) and high (4.0 wt%) Ni to research the effect of Ni on the bainite/martensite transformation. Results showed that deposited metals exhibited a multiphase structure comprised of bainite, martensite and residual austenite, which is not only explained from SEM/TEM, but also identified and quantified each phase from crystallographic structure through XRD and EBSD. With Ni content increasing, the fraction of martensite increases from 37% to 41%, and that of bainite decreases from 61% to 55% accordingly because 4% Ni element narrows the temperature range of the bainite transformation ~20 °C. The 7.8% residual austenite exhibited block and sheet in the deposited metal with low Ni, while the fraction of residual austenite was 3.26% as a film with high Ni, caused by different transformation mechanisms of bainite and martensite. The tensile strengths of deposited metals were 1042 ± 10 MPa (2.5% Ni) and 1040 ± 5 MPa (4% Ni), respectively. The yield strength of deposited metals with high Ni was 685 ± 18 MPa, which was higher than low Ni due to the high fraction of martensite. The impact values of deposited metals with high Ni content decreased because the volume fraction of bainite and residual austenite and area fraction of large-angle grain boundary were lower

Effect of H2S Corrosion on the Fracture Toughness of the X80 Pipeline Steel Welded Joint

To analyze the causes and mechanisms affecting the fracture toughness of X80 pipeline steel welded joints against H2S, the fracture toughness of different zones of X80 pipeline steel welded joints in both air and saturated H2S solution was investigated. The fracture toughness of welded joints degraded significantly in the saturated H2S solution, where the crack tip opening displacement (CTOD) characteristic value in the coarse grain heat-affected zone (CGHAZ) and weld metal (WM) was only 8% and 12% of that in air, respectively. However, the sub-critical grain heat-affected zone (SCHAZ) showed better resistance to H2S corrosion, with the CTOD characteristic value reaching 42% of that in air. The resistance of the welded joint to H2S corrosion was sensitive to microstructures. The grain boundary ferrite (GBF) presented in WM, and the angle of grain boundary orientation in CGHAZ was not conducive to hindering crack propagation. Moreover, the formation of the resultant hydrogen cracks owing to the H2S corrosion also reduced the fracture toughness of the welded joint