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The needs of power spectral density in fatigue life prediction of heavy vehicle leaf spring
Lennie Abdullah,Salvinder Singh Karam Singh,Shahrum Abdullah,Abdul Hadi Azman,Ahmad Kamal Ariffin,Yat Sheng Kong 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6
This study characterized the properties of random strain loading data for using power spectral density (PSD) in frequency domain of a heavy vehicle leaf spring. This is due to missing data caused by the sensitivity of the strain gauges in capturing strain signal. Strain signal was captured from a leaf spring component for 100 s at a sampling rate of 200 Hz using strain gauge. Fatigue life prediction was computed using strain-life models: Coffin-Manson, Morrow and Smith-Watson-Topper (SWT). The fatigue strain data showed that downhill data produces the lowest fatigue life prediction at 3.42 × 10 2 cycles/block with high energy of 3.6 × 10 4 µɛ 2 .Hz -1 ; then it was followed by curve and highway data. This was supported by the rootmean-square (RMS) value at 324.24 µɛ as it is directly related towards the PSD based on the energy contained for each captured signal. The correlation of fatigue life and strain amplitude was calculated to identify the distribution of fatigue strain data of leaf spring. Thus, the fatigue strain loading data can be characterized properly based on the energy content in PSD, the statistical parameter in the form of RMS value and the correlation with strain amplitude for random strain loading of leaf spring.
Lee, Kyoung Suk,Lennie, Terry A.,Yoon, Ju Young,Wu, Jia-Rong,Moser, Debra K. ASPEN PUBLISHERS INC 2017 JOURNAL OF CARDIOVASCULAR NURSING Vol.32 No.2
<P>Background: Depressive symptoms hinder heart failure patients' engagement in self-care. As social support helps improve self-care and decrease depressive symptoms, it is possible that social support buffers the negative impact of depressive symptoms on self-care. Objective: The purpose of this study is to examine the effect of living arrangements as an indicator of social support on the relationship between depressive symptoms and self-care in heart failure patients. Methods: Stable heart failure patients (N = 206) completed the Patient Health Questionnaire-9 to measure depressive symptoms. Self-care (maintenance, management, and confidence) was measured with the Self-Care of Heart Failure Index. Path analyses were used to examine associations among depressive symptoms and the self-care constructs by living arrangements. Results: Depressive symptoms had a direct effect on self-care maintenance and management (standardized beta = -0.362 and -0.351, respectively), but not on self-care confidence in patients living alone. Depressive symptoms had no direct or indirect effect on any of the 3 self-care constructs in patients living with someone. Conclusions: Depressive symptoms had negative effects on self-care in patients living alone, but were not related to self-care in patients living with someone. Our results suggest that negative effects of depressive symptoms on self-care are buffered by social support.</P>
Obesity Paradox: Comparison of Heart Failure Patients With and Without Comorbid Diabetes
Lee, Kyoung Suk,Moser, Debra K.,Lennie, Terry A.,Pelter, Michele M.,Nesbitt, Thomas,Southard, Jeffrey A.,Dracup, Kathleen AMERICAN ASSOCIATION OF CRITICAL CARE NURSES 2017 American journal of critical care Vol.26 No.2
Juluri, Bala Krishna,Lin, Wu,Lim, Lennie E N Korean Society for Precision Engineering 2007 International Journal of Precision Engineering and Vol.8 No.4
Existing long range piezoelectric motors with friction based transmission mechanisms are limited by the axial load capacity. To overcome this problem, a new linear piezoelectric motor using one piezoelectric actuator combined with a novel stepping mechanism is reported in this paper. To obtain both long range and fine accuracy, dual positioning control strategy consisting of coarse positioning and fine positioning is used. Coarse positioning is used for long travel range by accumulating motion steps obtained by piezoelectric actuator. This is followed by fine positioning where required accuracy is obtained by fine motion displacement of piezoelectric actuator. This prototype is able to provide resolution of 20 nanometers and withstand a maximum axial load of 300N. At maximum load condition, the positioner can move forward to a travel distance of 5mm at a maximum speed of 0.4 mm/sec. This design of nanopositioner can be used in applications for ultra precision positioning and grinding operations where high axial force capacity is required.
Bala Krishna Juluri,Wu Lin,Lennie E N Lim 한국정밀공학회 2007 International Journal of Precision Engineering and Vol.8 No.4
Existing long range piezoelectric motors with friction based transmission mechanisms are limited by the axial load capacity. To overcome this problem. a new linear piezoelectric motor using one piezoelectric actuator combined with a novel stepping mechanism is reported in this paper. To obtain both long range and fine accuracy, dual positioning control strategy consisting of coarse positioning and fine positioning is used. Coarse positioning is used for long travel range by accumulating motion steps obtained by piezoelectric actuator. This is followed by fine positioning where required accuracy is obtained by fine motion displacement of piezoelectric actuator. This prototype is able to provide resolution of 20 nanometers and withstand a maximum axial load of 300N. At maximum load condition, the positioner can move forward to a travel distance of 5mm at a maximum speed of 0.4 mm/sec. This design of nanopositioner can be used in applications for ultra precision positioning and grinding operations where high axial force capacity is required.
Song, Eun Kyeung,Moser, Debra K,Dunbar, Sandra B,Pressler, Susan J,Lennie, Terry A SAGE Publications 2014 European journal of cardiovascular nursing Vol.13 No.6
<P><B>Background:</B></P><P>Despite a growing recognition that a strict low sodium diet may not be warranted in compensated heart failure (HF) patients, the link between sodium restriction below 2 g/day and health outcomes is unknown in patients at different levels of HF severity.</P><P><B>Purpose:</B></P><P>The purpose of this study was to compare differences in event-free survival among patients with <2 g/day, 2–3 g/day, or >3 g/day sodium intake stratified by New York Heart Association (NYHA) class.</P><P><B>Method:</B></P><P>A total of 244 patients with HF completed a four-day food diary to measure daily sodium intake. All-cause hospitalization or death for a median of 365 follow-up days and covariates on age, gender, etiology, body mass index, NYHA class, ejection fraction, total comorbidity score, the presence of ankle edema, and prescribed medications were determined by patient interview and medical record review. Hierarchical Cox hazard regression was used to address the purpose.</P><P><B>Results:</B></P><P>In NYHA class I/II (<I>n</I>=134), patients with <2 g/day sodium intake had a 3.7-times higher risk (<I>p</I>=0.025), while patients with >3 g/day sodium intake had a 0.4-times lower risk (<I>p</I>=0.047) for hospitalization or death than those with 2–3 g/day sodium intake after controlling for covariates. In NYHA class III/IV (<I>n</I>=110), >3 g/day sodium intake predicted shorter event-free survival (<I>p</I>=0.044), whereas there was no difference in survival curves between patients with <2 g/day and those with 2–3 g/day sodium intake.</P><P><B>Conclusion:</B></P><P>Sodium restriction below 2 g/day is not warranted in mild HF patients, whereas excessive sodium intake above 3 g/day may be harmful in moderate to severe HF patients.</P>
Self-reported Adherence to a Low-Sodium Diet and Health Outcomes in Patients With Heart Failure :
Song, Eun Kyeung,Moser, Debra K.,Kang, Seok-Min,Lennie, Terry A. ASPEN PUBLISHERS INC 2016 JOURNAL OF CARDIOVASCULAR NURSING Vol.31 No.6
<P>Background: Most clinicians rely on patients' self-report of following a low-sodium diet to determine adherence of patients with heart failure (HF). Whether self-reported adherence to a low-sodium diet is associated with cardiac eventYfree survival is unclear. Purposes: To determine (1) whether self-reported is concordant with adherence to a low-sodium diet measured by food diaries and 24-hour urinary sodium excretion and (2) whether self-reported adherence to a low-sodium diet predicts cardiac eventYfree survival. Methods: Adherence to a low-sodium diet was measured using 3 measures in 119 HF patients: (1) self-reported adherence, 1 item from the Self-care of Heart Failure Index scale; (2) a 3-day food diary; (3) 24-hour urinary sodium excretion. Patients were followed up for a median of 297 days to determine cardiac hospitalization or emergency department visit. One-way analysis of variance and Cox regression were used to address our purposes. Results: Self-reported adherence was concordant with adherence to a low-sodium diet measured by food diaries and 24-hour urinary sodium excretion. Thirty-one patients who reported they always follow a low-sodium diet had an average sodium intake less than 3 g/d (F = 5.07, P =.002) and 3.3 g of a mean 24-hour urinary sodium excretion (F = 3.393, P =.020). Patients who reported they never or rarely follow a low-sodium diet had 4.7 times greater risk of having cardiac events than did those who always followed a low-sodium diet (P =.017). Conclusion: Self-reported adherence to a low-sodium diet predicted cardiac eventYfree survival demonstrating clinicians can use this as an indicator of adherence.</P>