scholarly journals Statistical Reliability Assessment for Small Sample of Failure Data of Dumper Diesel Engines Based on Power Law Process and Maximum Likelihood Estimation

2021 ◽  
Vol 11 (12) ◽  
pp. 5387
Author(s):  
Brajeshkumar Kishorilal Dinkar ◽  
Alok Kumar Mukhopadhyay ◽  
Somnath Chattopadhyaya ◽  
Shubham Sharma ◽  
Firoz Alam ◽  
...  
Keyword(s):  
Diesel Engines ◽  
Hypothesis Test ◽  
Meta Analysis ◽  
Likelihood Estimation ◽  
Small Sample ◽  
Trend Test ◽  
Failure Data ◽  
Subsystem Level ◽  
Dump Trucks ◽  
Engine Failure

Dumpers or dump trucks are used all over the world to move overburden from many opencast mines. Diesel engines are the main driving force behind the trucks. The frequency of damage due to the failure of diesel engines is enormous. Therefore, efforts are necessary to analyze failure to reduce the downtime periods. A detailed analysis of engine failure at the subsystem level needs to be done. Reliability analysis and maintenance planning remain the norm in this regard. The obstacle faced while analysing the reliability of dumpers was the availability of a large number of data failures. In this paper, this issue is addressed by using Common Beta Hypothesis test and Meta-analysis test. The engine is divided into five subsystems. The result shows that all five subsystems pass the CBH test and Meta-analysis test. Accordingly, the failure data is grouped. The trend test of grouped failure data shows that the Failure data of two subsystems follows the independent and identically distributed characteristics while the remaining three do not follow it. The reliability is estimated for all five subsystems. Finally, fuel supply subsystems show the highest reliability while the lowest value is seen for self-starting subsystems.

The Theoretical and Experimental Research on Accelerated Life Test of Collapsible Fabric Tank Storage Life Based on Reliability

2013 ◽  
Vol 853 ◽  
pp. 590-595
Author(s):  
Shi Fu Zhang ◽  
Tian Min Liu ◽  
Qi Xin Zhang ◽  
Xiu Mei Shu ◽  
Shi Qiang Song ◽  
...  
Keyword(s):  
Goodness Of Fit ◽  
Evaluation Method ◽  
Storage Temperature ◽  
Hypothesis Test ◽  
Likelihood Estimation ◽  
Storage Life ◽  
Accelerated Life Test ◽  
Model Parameters ◽  
Failure Data ◽  
Tank Storage

Collapsible fabric tank which is an important part of oil equipment equips army with large reserves. The evaluation of collapsible fabric tank storage life, lacking of corresponding test data support, is on the conservative side, which causes manage and storage uncertainty to army. Based on reliability theory, storage life evaluation method of collapsible fabric tank is established. Failure data of collapsible fabric tank under several accelerated stress levels is obtained. According to probability distribution hypothesis test, Weibull distribution has better goodness of fit and life prediction model is obtained. A new maximum likelihood estimation is proposed as statistical analysis method and model parameters are evaluated. Storage life and reliability index of collapsible fabric tank under normal storage temperature are evaluated which brings collapsible fabric tank storage life potential into play and improves use economy.

Neural Underpinnings of Numerical and Spatial Cognition: An fMRI Meta-Analysis of Brain Regions Associated with Symbolic Number, Arithmetic, and Mental Rotation

2019 ◽  
Author(s):  
Zachary Hawes ◽  
H Moriah Sokolowski ◽  
Chuka Bosah Ononye ◽  
Daniel Ansari
Keyword(s):  
Mental Rotation ◽  
Parietal Lobe ◽  
Meta Analysis ◽  
Likelihood Estimation ◽  
Brain Regions ◽  
Angular Gyrus ◽  
Number Representation ◽  
Neural Underpinnings ◽  
The Right ◽  
Symbolic Number

Where and under what conditions do spatial and numerical skills converge and diverge in the brain? To address this question, we conducted a meta-analysis of brain regions associated with basic symbolic number processing, arithmetic, and mental rotation. We used Activation Likelihood Estimation (ALE) to construct quantitative meta-analytic maps synthesizing results from 86 neuroimaging papers (~ 30 studies/cognitive process). All three cognitive processes were found to activate bilateral parietal regions in and around the intraparietal sulcus (IPS); a finding consistent with shared processing accounts. Numerical and arithmetic processing were associated with overlap in the left angular gyrus, whereas mental rotation and arithmetic both showed activity in the middle frontal gyri. These patterns suggest regions of cortex potentially more specialized for symbolic number representation and domain-general mental manipulation, respectively. Additionally, arithmetic was associated with unique activity throughout the fronto-parietal network and mental rotation was associated with unique activity in the right superior parietal lobe. Overall, these results provide new insights into the intersection of numerical and spatial thought in the human brain.

A historical cohort of temporal lobe surgery for medically refractory epilepsy: a systematic review and meta-analysis to guide future nonrandomized controlled trial studies

2020 ◽  
Vol 133 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Anthony T. Lee ◽  
John F. Burke ◽  
Pranathi Chunduru ◽  
Annette M. Molinaro ◽  
Robert Knowlton ◽  
...  
Keyword(s):  
Systematic Review ◽  
Temporal Lobe ◽  
Epilepsy Surgery ◽  
Refractory Epilepsy ◽  
Meta Analysis ◽  
Small Sample ◽  
Seizure Freedom ◽  
Level I ◽  
Study Designs ◽  
Medically Refractory Epilepsy

OBJECTIVERecent trials for temporal lobe epilepsy (TLE) highlight the challenges of investigating surgical outcomes using randomized controlled trials (RCTs). Although several reviews have examined seizure-freedom outcomes from existing data, there is a need for an overall seizure-freedom rate estimated from level I data as investigators consider other methods besides RCTs to study outcomes related to new surgical interventions.METHODSThe authors performed a systematic review and meta-analysis of the 3 RCTs of TLE in adults and report an overall surgical seizure-freedom rate (Engel class I) composed of level I data. An overall seizure-freedom rate was also collected from level II data (prospective cohort studies) for validation. Eligible studies were identified by filtering a published Cochrane meta-analysis of epilepsy surgery for RCTs and prospective studies, and supplemented by searching indexed terms in MEDLINE (January 1, 2012–April 1, 2018). Retrospective studies were excluded to minimize heterogeneity in patient selection and reporting bias. Data extraction was independently reverified and pooled using a fixed-effects model. The primary outcome was overall seizure freedom following surgery. The historical benchmark was applied in a noninferiority study design to compare its power to a single-study cohort.RESULTSThe overall rate of seizure freedom from level I data was 72.4% (55/76 patients, 3 RCTs), which was nearly identical to the overall seizure-freedom rate of 71.7% (1325/1849 patients, 18 studies) from prospective cohorts (z = 0.134, p = 0.89; z-test). Seizure-freedom rates from level I and II studies were consistent over the years of publication (R2< 0.01, p = 0.73). Surgery resulted in markedly improved seizure-free outcomes compared to medical management (RR 10.82, 95% CI 3.93–29.84, p < 0.01; 2 RCTs). Noninferiority study designs in which the historical benchmark was used had significantly higher power at all difference margins compared to using a single cohort alone (p < 0.001, Bonferroni’s multiple comparison test).CONCLUSIONSThe overall rate of seizure freedom for temporal lobe surgery is approximately 70% for medically refractory epilepsy. The small sample size of the RCT cohort underscores the need to move beyond standard RCTs for epilepsy surgery. This historical seizure-freedom rate may serve as a useful benchmark to guide future study designs for new surgical treatments for refractory TLE.

scholarly journals The incidence and prevalence of cardiovascular diseases in gout: a systematic review and meta-analysis

2021 ◽  
Author(s):  
Peter Cox ◽  
Sonal Gupta ◽  
Sizheng Steven Zhao ◽  
David M. Hughes
Keyword(s):  
Systematic Review ◽  
Cardiovascular Disease ◽  
Cardiovascular Risk ◽  
Cardiovascular Diseases ◽  
Small Sample Size ◽  
Meta Analysis ◽  
Random Effect ◽  
Small Sample ◽  
Future Research ◽  
Increased Risk

AbstractThe aims of this systematic review and meta-analysis were to describe prevalence of cardiovascular disease in gout, compare these results with non-gout controls and consider whether there were differences according to geography. PubMed, Scopus and Web of Science were systematically searched for studies reporting prevalence of any cardiovascular disease in a gout population. Studies with non-representative sampling, where a cohort had been used in another study, small sample size (< 100) and where gout could not be distinguished from other rheumatic conditions were excluded, as were reviews, editorials and comments. Where possible meta-analysis was performed using random-effect models. Twenty-six studies comprising 949,773 gout patients were included in the review. Pooled prevalence estimates were calculated for five cardiovascular diseases: myocardial infarction (2.8%; 95% confidence interval (CI)s 1.6, 5.0), heart failure (8.7%; 95% CI 2.9, 23.8), venous thromboembolism (2.1%; 95% CI 1.2, 3.4), cerebrovascular accident (4.3%; 95% CI 1.8, 9.7) and hypertension (63.9%; 95% CI 24.5, 90.6). Sixteen studies reported comparisons with non-gout controls, illustrating an increased risk in the gout group across all cardiovascular diseases. There were no identifiable reliable patterns when analysing the results by country. Cardiovascular diseases are more prevalent in patients with gout and should prompt vigilance from clinicians to the need to assess and stratify cardiovascular risk. Future research is needed to investigate the link between gout, hyperuricaemia and increased cardiovascular risk and also to establish a more thorough picture of prevalence for less common cardiovascular diseases.

scholarly journals Grey matter abnormalities in Tourette syndrome: an activation likelihood estimation meta-analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Fang Wen ◽  
Junjuan Yan ◽  
Liping Yu ◽  
Fang Wang ◽  
Jingran Liu ◽  
...  
Keyword(s):  
Tourette Syndrome ◽  
Grey Matter ◽  
Meta Analysis ◽  
Likelihood Estimation ◽  
Anterior Cingulate ◽  
Precentral Gyrus ◽  
Healthy Controls ◽  
Activation Likelihood Estimation ◽  
Lentiform Nucleus ◽  
Postcentral Gyrus

Abstract Background Tourette syndrome (TS) is a neurodevelopmental disorder defined by the continual presence of primary motor and vocal tics. Grey matter abnormalities have been identified in numerous studies of TS, but conflicting results have been reported. This study was an unbiased statistical meta-analysis of published neuroimaging studies of TS structures. Methods A voxel quantitative meta-analysis technique called activation likelihood estimation (ALE) was used. The meta-analysis included six neuroimaging studies involving 247 TS patients and 236 healthy controls. A statistical threshold of p < 0.05 was established based on the false discovery rate and a cluster extent threshold of 50 voxels. Results We found that grey matter volumes were significantly increased in the bilateral thalamus, right hypothalamus, right precentral gyrus, left postcentral gyrus, left inferior parietal lobule, right lentiform nucleus, and left insula of TS patients compared to those of healthy controls. In contrast, grey matter volumes were significantly decreased in the bilateral postcentral gyrus, bilateral anterior cingulate, bilateral insula, left posterior cingulate and left postcentral gyrus of TS patients compared to those of healthy controls. Conclusions Our present meta-analysis primarily revealed significant increases in grey matter volumes in the thalamus and lentiform nucleus, and decreased grey matter volumes in the anterior cingulate gyrus, of TS patients compared to those in healthy controls. Most of these identified regions are associated with cortico-striato-thalamo-cortical circuits. Further studies with larger sample sizes are needed to confirm these changes in grey matter volumes in TS patients.

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