scholarly journals A New Method for Friction Estimation in EMA Transmissions

Actuators ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 194
Author(s):  
Gaetano Quattrocchi ◽  
Alessandro Iacono ◽  
Pier C. Berri ◽  
Matteo D. L. Dalla Dalla Vedova ◽  
Paolo Maggiore

The increasing interest for adopting electromechanical actuators (EMAs) on aircraft demands improved diagnostic and prognostic methodologies to be applied to such systems in order to guarantee acceptable levels of reliability and safety. While diagnostics methods and techniques can help prevent fault propagation and performance degradation, prognostic methods can be applied in tandem to reduce maintenance costs and increase overall safety by enabling predictive and condition-based maintenance schedules. In this work, a predictive approach for EMAs friction torque estimation is proposed. The algorithm is based on the reconstruction of the residual torque in mechanical transmissions. The quantity is then sampled and an artificial neural network (ANN) is used to obtain an estimation of the current health status of the transmission. Early results demonstrate that such an approach can predict the transmission health status with good accuracy.

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 50 ◽  
Author(s):  
Gaetano Quattrocchi ◽  
Pier C. Berri ◽  
Matteo D. L. Dalla Vedova ◽  
Paolo Maggiore

The ever increasing adoption of electrical power as secondary form of on-board power is leading to an increase in the usage of electromechanical actuators (EMAs). Thus, in order to maintain an acceptable level of safety and reliability, innovative prognostics and diagnostics methodologies are needed to prevent performance degradation and/or faults propagation. Furthermore, the use of effective prognostics methodologies carries several benefits, including improved maintenance schedule capability and relative cost decrease, better knowledge of systems health status and performance estimation. In this work, a novel, real-time approach to EMAs prognostics is proposed. The reconstructed back electromotive force (back-EMF), determined using a virtual sensor approach, is sampled and then used to train an artificial neural network (ANN) in order to evaluate the current system status and to detect possible coils partial shorts and rotor imbalances.


1988 ◽  
Vol 20 (3) ◽  
pp. 265-274 ◽  
Author(s):  
Roy A. Carr-Hill

SummaryThe conventional belief since the publication of the Black Report is that social inequalities in health have been increasing since 1931–32 although it has been argued that the measure of inequality used is inappropriate. All analyses have been based on mortality rates which, in large part, reflect inequalities in health over the previous 50 years and not current trends. This paper argues that time trends should be assessed with a current health status measure and suggests using height at age 20 as a good measure of the achieved health status of a group. Analysis of a government survey shows that inequalities have stayed the same since 1940, both for men classified by their own occupation and for women classified by their father's occupation.


Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 27
Author(s):  
Sehrish Malik ◽  
DoHyeun Kim

The prediction mechanism is very crucial in a smart factory as they widely help in improving the product quality and customer’s experience based on learnings from past trends. The implementation of analytics tools to predict the production and consumer patterns plays a vital rule. In this paper, we put our efforts to find integrated solutions for smart factory concerns by proposing an efficient task management mechanism based on learning to scheduling in a smart factory. The learning to prediction mechanism aims to predict the machine utilization for machines involved in the smart factory, in order to efficiently use the machine resources. The prediction algorithm used is artificial neural network (ANN) and the learning to prediction algorithm used is particle swarm optimization (PSO). The proposed task management mechanism is evaluated based on multiple scenario simulations and performance analysis. The comparisons analysis shows that proposed task management system significantly improves the machine utilization rate and drastically drops the tasks instances missing rate and tasks starvation rate.


2017 ◽  
Vol 5 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Elizabeth Vera ◽  
Alvina A Acquaye ◽  
Tito R Mendoza ◽  
Mark R Gilbert ◽  
Terri S Armstrong

Abstract Background Patients with glioma are highly symptomatic and often have functional limitations from the time of diagnosis. Measuring health status may have value in determining impact of disease. This study provided a description of health status and utility scores in glioma patients throughout the illness trajectory using the EQ-5D (a functional measure of general health status). Furthermore, it evaluated the information provided by the MD Anderson Symptom Inventory-Brain Tumor (MDASI-BT; a measure of symptom burden and interference) in describing health-related quality of life as assessed by the EQ-5D. Methods Glioma patients completed the EQ-5D and MDASI-BT. Disease and clinical details were collected by medical record review. Linear regression evaluated whether MDASI-BT scores adequately predict patient health outcomes measured by the EQ-5D. Results The sample included 100 patients (65% male, 78% with a glioblastoma, median age 52 [range, 20–75], 56% in active treatment). Seventy-two percent of patients reported functional limitations in at least 1 area. Extreme cases reported inability to perform usual activities (8%) and significant anxiety/depression (5%). The MDASI-BT neurologic factor and activity-related interference (walking/activity/work) explained 52% of the variability in the EQ-5D in this patient population while adjusting for the effect of tumor grade, recurrence status, and performance status. Conclusions The majority of glioma patients reported at least 1 functional limitation on the EQ-5D. Over half of the variance in the EQ-5D was explained by the MDASI-BT, performance status, tumor grade, and recurrence status. The resultant model demonstrates the significant contribution of symptom burden on health status in glioma patients.


2004 ◽  
Vol 8 (38) ◽  
Author(s):  
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...  

Summary of new report published by WHO, assessing the current health status of the internally displaced people in Darfur, Sudan,


2015 ◽  
Author(s):  
◽  
Cai Hu

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Essay 1 analyzes the married couples' retirement decision using the PSID data. I employ the proportional hazard model to examine the factors that influence the retirement decision of husband and wife, and focus on examining the correlation of husband and wife's retirement status. This essay finds that an individual is more likely to retire if his or her spouse has retired. The retirement hazard is higher if an individual is in worse health. The worse health status also affects the spouse's retirement hazard, but the spouse effect is asymmetry. With the wife in worse health, the husband's retirement hazard decreases. With the husband in worse health, the wife's retirement hazard increases. I also find that the greater the social security income or pension, the higher the retirement hazard. But for the spouse effect, the husband's social security income or pension has impact on the retirement schedule of his wife, while I find no significant impact of wife's retirement benefit on husband's retirement timing. Essay 2 explores the transitions of health status using PSID data from 1984 to 2011 with the ordered logit model and the Cox proportional hazards model. The result shows that the impact of current health status on future health status is relatively large. A worse current health status would lead to a smaller probability for health deterioration, but it is less likely to be in a good health status in the future. There is strong health persistence. Social economics factors' impact on latent health status is also significant, although the magnitude is relatively small. Higher income level and education level would decrease the likelihood of health deterioration, and individuals with high income and high education would be more likely to be in better health status. When comparing different occupations, white-collar job is less associated with health deterioration, and this type of worker is more likely to be in better health status. Essay 3 applies the competing risks model to estimate the movement of corporate credit ratings using WRDS COMPUSTAT data. The credit rating variable is the Standard and Poor's long-term domestic issuer credit rating. The explanatory variables contain measures of leverage, liquidity, current profitability and future profitability. I estimate the impacts of these financial ratios on the upward and downward of credit rating. In addition, I estimate samples before and after the 2008 subprime crisis to study the influence of financial crisis on the credit rating. The result shows that firms with a higher liquidity are more likely to be upgraded and less likely to be downgraded. The impact of liquidity is weaker after the crisis. I find that when the current level of profitability increases, the firm is more likely to be upgraded than to be downgraded. The effect of current profitability is larger after the crisis. Firms with higher leverage ratio are more likely to be upgraded and less likely to be downgraded. And the effect of leverage is similar before and after the crisis.


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