scholarly journals Inspection optimization of load-sharing systems

2021 ◽  
Author(s):  
Maryam L. Kassaei
Keyword(s):  
Failure Rate ◽  
Load Sharing ◽  
Cumulative Exposure ◽  
Current Load ◽  
Independent Components ◽  
Periodic Inspection ◽  
Inspection Interval ◽  
History Of ◽  
Load Intensity

In this thesis, periodic inspection of a load-sharing k-out-of-n system has been studied to obtain the optimal inspection interval using the analytical and simulation approaches. The components of a load-sharing system are stochastically dependent, which makes the analysis of these systems more complex than those with independent components. In order to acquire the optimal inspection interval for the system, two models have been developed to study load-sharing systems with Tampered Failure Rate (TFR) and Cumulative Exposure (CE). The former considers only the current load of the components and the later accounts for the history of load. Various load intensities are examined to study the effects of this parameter on each model. It is observed that as the load intensity increases, the system needs more frequent inspections. The results also reveal that a system with the CE model requires a shorter inspection interval in comparison to that with the TFR model.

scholarly journals Inspection optimization of load-sharing systems

2021 ◽  
Author(s):  
Maryam L. Kassaei
Keyword(s):  
Failure Rate ◽  
Load Sharing ◽  
Cumulative Exposure ◽  
Current Load ◽  
Independent Components ◽  
Periodic Inspection ◽  
Inspection Interval ◽  
History Of ◽  
Load Intensity

In this thesis, periodic inspection of a load-sharing k-out-of-n system has been studied to obtain the optimal inspection interval using the analytical and simulation approaches. The components of a load-sharing system are stochastically dependent, which makes the analysis of these systems more complex than those with independent components. In order to acquire the optimal inspection interval for the system, two models have been developed to study load-sharing systems with Tampered Failure Rate (TFR) and Cumulative Exposure (CE). The former considers only the current load of the components and the later accounts for the history of load. Various load intensities are examined to study the effects of this parameter on each model. It is observed that as the load intensity increases, the system needs more frequent inspections. The results also reveal that a system with the CE model requires a shorter inspection interval in comparison to that with the TFR model.

scholarly journals Asbestos Exposure of Chrysotile Miners and Millers in Balangero, Italy

2020 ◽  
Vol 64 (6) ◽  
pp. 636-644
Author(s):  
Stefano Silvestri ◽  
Daniela Ferrante ◽  
Andrea Giovannini ◽  
Francesco Grassi ◽  
Stefania Carofalo ◽  
...  
Keyword(s):  
Cohort Study ◽  
Working Conditions ◽  
Western Europe ◽  
Asbestos Exposure ◽  
Industrial Hygiene ◽  
Cumulative Exposure ◽  
State Archive ◽  
Work Area ◽  
Russian Study ◽  
History Of

Abstract The largest chrysotile mine in Western Europe was active in Balangero (Italy) from 1917 to 1990. We quantitatively assessed exposure to asbestos in the framework of a cohort study on mortality of Balangero miners and millers. Using documents filed at the Italian State Archive we reconstructed the job-histories of cohort members. The concentration of asbestos fibres by work-area was derived from industrial hygiene surveys since 1968 and monitoring programs since 1975. Earlier exposures had been estimated based on the experimental reconstruction of past working conditions. In the mine concentrations of about 20 fibres per millilitre (f/ml) were initially present, decreasing to 5 in the mid-1950s and to <1 in late 1970s. In milling areas higher levels were present and did not fall below 1 f/ml until the mid-1980s. Cumulative exposure of cohort members, as the sum over their job-history of their year- and area-specific exposures, were <10 fibre/millilitre years (f/ml-y) in 18% of workers, 10–100 in 32%, 100–1000 in 37%, and >1000 in 13%. Compared with recently published estimates for the Russian chrysotile mine in Asbest, fibre concentrations in Balangero were higher during the 1950s and 1960s. Such difference may be partly accounted for by difficulties in converting dust measurements to fibre concentrations in the Russian study and the need to rely on the experimental reconstruction of exposures before 1968 in our study.

Risk Factors for Chronic Traumatic Encephalopathy: A Proposed Framework

2020 ◽  
Vol 40 (04) ◽  
pp. 439-449
Author(s):  
Alyssa Phelps ◽  
Jesse Mez ◽  
Robert A. Stern ◽  
Michael L. Alosco
Keyword(s):  
Risk Factors ◽  
Chronic Traumatic Encephalopathy ◽  
Military Veterans ◽  
Cumulative Exposure ◽  
Risk Characterization ◽  
Future Directions ◽  
Head Impacts ◽  
Environmental Trigger ◽  
History Of ◽  
Pathological Development

AbstractChronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disease that has been neuropathologically diagnosed in contact and collision sport athletes, military veterans, and others with a history of exposure to repetitive head impacts (RHI). Identifying methods to diagnose and prevent CTE during life is a high priority. Timely diagnosis and implementation of treatment and preventative strategies for neurodegenerative diseases, including CTE, partially hinge upon early and accurate risk characterization. Here, we propose a framework of risk factors that influence the neuropathological development of CTE. We provide an up-to-date review of the literature examining cumulative exposure to RHI as the environmental trigger for CTE. Because not all individuals exposed to RHI develop CTE, the direct and/or indirect influence of nonhead trauma exposure characteristics (e.g., age, sex, race, genetics) on the pathological development of CTE is reviewed. We conclude with recommendations for future directions, as well as opinions for preventative strategies that could mitigate risk.

The effect of warfarin on the risk of prostate cancer

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 14524-14524
Author(s):  
V. Tagalakis ◽  
H. Tamim ◽  
J. Collet ◽  
S. R. Kahn ◽  
M. Blostein ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cancer Diagnosis ◽  
Conditional Logistic Regression ◽  
Oral Anticoagulants ◽  
Large Population ◽  
Population Based ◽  
Cumulative Exposure ◽  
Prolonged Treatment ◽  
History Of ◽  
Reduced Risk

14524 Background: The anticancer activity of oral anticoagulants has been a matter of debate for several years. Recent evidence suggests that prolonged treatment with warfarin may be associated with a reduced incidence of newly diagnosed urogenital cancer during long-term follow-up of patients with venous thromboembolism. The aim of this study was to assess whether exposure to warfarin was associated with reduced risk of prostate cancer in a large population-based cohort. Methods: We conducted a matched case-control study nested within the population of beneficiaries of the Saskatchewan Prescription Drug Plan aged 50 years and older from 1981–2002 with no history of cancer since 1967. New cases of prostate cancer diagnosed between 1981 and 2002 were identified using the linked Saskatchewan Cancer Agency registry. Six controls per case matched on age, gender, and sampling time were randomly selected. The cumulative exposure to warfarin in the five years preceding the cancer diagnosis was assessed. Prescription counts were used to define warfarin exposure. Exposure in the year immediately preceding the cancer diagnosis was excluded to control for detection bias. Conditional logistic regression analysis was used to assess confounding by other drugs such as nonsteroidal anti-inflammatory medications. Results: Among 11502 cases and 69012 controls, 7.4% of cases and 7.1% of controls had a history of any warfarin use. Compared to men who had never used warfarin, adjusted odds ratio (OR) for prostate cancer among ever-users in the 5 year period was 0.94 (95% confidence interval (CI), 0.86–1.03). In those who accumulated 1, 2, 3 and 4 years of warfarin use, the adjusted ORs were 1.01 (95% CI, 0.89–1.16), 1.00 (95% CI, 0.82–1.23), 0.81 (95% CI, 0.60–1.09), and 0.80 (95% CI, 0.65–0.99), respectively (p-trend=0.03). Conclusion: Our results suggest that cumulative use of warfarin of at least 4 years may be associated with a reduced risk of prostate cancer. However, confounding by other determinants of prostate cancer associated with warfarin use is possible. Nonetheless, confirmation of these findings by prospective studies may provide the evidence necessary to consider the use of warfarin in prostate cancer prevention. No significant financial relationships to disclose.

scholarly journals Reliability Analysis of Load-SharingK-out-of-NSystem Considering Component Degradation

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Chunbo Yang ◽  
Shengkui Zeng ◽  
Jianbin Guo
Keyword(s):  
Reliability Analysis ◽  
Failure Rate ◽  
Load Sharing ◽  
Performance Degradation ◽  
Random Component ◽  
Rate Model ◽  
Successful Operation ◽  
Degradation Model ◽  
System Requirement ◽  
Degradation Effect

TheK-out-of-Nconfiguration is a typical form of redundancy techniques to improve system reliability, where at leastK-out-of-Ncomponents must work for successful operation of system. When the components are degraded, more components are needed to meet the system requirement, which means that the value ofKhas to increase. The current reliability analysis methods overestimate the reliability, because using constantKignores the degradation effect. In a load-sharing system with degrading components, the workload shared on each surviving component will increase after a random component failure, resulting in higher failure rate and increased performance degradation rate. This paper proposes a method combining a tampered failure rate model with a performance degradation model to analyze the reliability of load-sharingK-out-of-Nsystem with degrading components. The proposed method considers the value ofKas a variable which is derived by the performance degradation model. Also, the load-sharing effect is evaluated by the tampered failure rate model. Monte-Carlo simulation procedure is used to estimate the discrete probability distribution ofK. The case of a solar panel is studied in this paper, and the result shows that the reliability considering component degradation is less than that ignoring component degradation.

Dynamic reliability models of mechanical load-sharing parallel systems considering strength degradation of components

2014 ◽  
Vol 229 (13) ◽  
pp. 2484-2495 ◽  
Author(s):  
Peng Gao ◽  
Liyang Xie
Keyword(s):  
Failure Rate ◽  
Mechanical Load ◽  
Parallel Systems ◽  
Load Sharing ◽  
Strength Degradation ◽  
Random Load ◽  
Dynamic Reliability ◽  
Reliability Models ◽  
Load Redistribution ◽  
Mechanical Components

Conventional reliability analysis of load-sharing parallel systems is mainly based on failure rate of components, in which failure dependence of components and load redistribution are also characterized by specified failure rates. However, the failure rate of mechanical components always varies with time, which is difficult to measure. Therefore, in this paper, quantitative dynamic reliability models of mechanical load-sharing parallel systems are developed in terms of stress parameters and strength parameters rather than failure rate of components, which consider the degradation mechanism of mechanical components. The proposed models take into account the strength degradation path dependence (SDPD) of a component, the strength degradation process dependence between different components in a system, and the random load redistribution. In addition, Monte Carlo simulation is carried out to verify the proposed models. The results show that SDPD and the load-sharing effect have considerable influences on dynamic reliability of mechanical load-sharing parallel systems.

scholarly journals 11β-Hydroxylase (CYP11B1) gene variants and new-onset depression in later life

2020 ◽  
Vol 46 (1) ◽  
pp. E147-E153
Author(s):  
Marie-Laure Ancelin ◽  
Joanna Norton ◽  
Karen Ritchie ◽  
Isabelle Chaudieu ◽  
Joanne Ryan
Keyword(s):  
Major Depression ◽  
Major Gene ◽  
Depression Scale ◽  
Late Life ◽  
Later Life ◽  
Cumulative Exposure ◽  
Late Life Depression ◽  
Recurrent Depression ◽  
History Of ◽  
New Onset

Background: Cumulative exposure to high glucocorticoid levels is detrimental for the brain and may have particular implications in later life. A feature of late-life depression is increased cortisol secretion. Variants in the CYP11B1 gene, which codes for the enzyme responsible for cortisol synthesis, could influence risk of late-life depression, but this hypothesis has not been examined. We investigated the associations between variants in the CYP11B1 gene and late-life depression, taking into account history of depression and potential sexspecific effects. Methods: We assessed depression in 1007 community-dwellers aged 65 years or older (60% women) at baseline and over a 14-year follow-up. A clinical level of depression was defined as a score of ≥ 16 on the Centre for Epidemiology Studies Depression scale or a diagnosis of current major depression based on the Mini-International Neuropsychiatric Interview and according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV). We examined incident and recurrent depression in participants without or with a history of major depression, respectively. We genotyped 5 single-nucleotide polymorphisms (SNPs) spanning CYP11B1. We used multivariable analyses to adjust for age, body mass index, cardiovascular ischemic pathologies, hypertension, cognitive impairment and anxiety. Results: In women, rs6471580 and rs7016924 were associated with a 50% lower rate of incident (new-onset) late-life depression, and rs11783855 was associated with a 2.4-fold higher rate of late-life depression. These associations remained after correction for multiple testing, but we found no associations for recurrent depression in women or men. Limitations: This study focused on the major gene involved in corticosteroid biosynthesis, but other genes may also be implicated in this pathway. Conclusion: Variants of the CYP11B1 gene appear to be susceptibility factors for late-life depression in a sex-specific manner.

scholarly journals Ectopic Pregnancy Following Interval Tubal Sterilization

2017 ◽  
Vol 5 (2) ◽  
pp. 77-80
Author(s):  
Deepak Shrestha ◽  
Sebina Baniya ◽  
Sudeep Regmi
Keyword(s):  
Ectopic Pregnancy ◽  
Failure Rate ◽  
Uterine Cavity ◽  
Prior History ◽  
Emergency Laparotomy ◽  
Tubal Sterilization ◽  
Mobile Mass ◽  
History Of ◽  
Permanent Contraception ◽  
Urine Pregnancy Test

Introduction:  Tubal sterilization is a highly effective method of permanent contraception. However, pregnancy can still occur following a successful procedure. Published literatures report a failure rate of 0.13-1.3% and 15-33% of such pregnancies are likely to be ectopic. Case report: A 33 years para three lady with prior history of tubal ligation presented with generalized abdominal pain and several episodes of vomiting. Bimanual examination revealed a soft and mobile mass of 2 x 3 cm in right adnexa. Urine pregnancy test was positive and ultrasonogram showed a heterogeneous mass of 3.4 x 3.3 cm in right adnexa with empty uterine cavity. Culdocentesis resulted in aspiration of frank non-clotting blood. She then underwent emergency laparotomy with bilateral salpingectomy for ruptured ectopic pregnancy. Conclusion: Ectopic pregnancy after tubal sterilization though rare is not entirely impossible. All women who are offered this procedure should always be educated about its failure rate. And in women presenting with acute abdomen, a prior history of tubal sterilization doesn't preclude the possibility of ectopic pregnancy.

scholarly journals Prior Bone Marrow Stimulation Surgery Influences Outcomes After Cell-Based Cartilage Restoration: A Systematic Review and Meta-analysis

2021 ◽  
Vol 9 (9) ◽  
pp. 232596712110353
Author(s):  
Charles J. Cogan ◽  
James Friedman ◽  
Jae You ◽  
Alan L. Zhang ◽  
Brian T. Feeley ◽  
...  
Keyword(s):  
Systematic Review ◽  
Bone Marrow ◽  
Failure Rate ◽  
Meta Analysis ◽  
Failure Rates ◽  
Bone Marrow Stimulation ◽  
Marrow Stimulation ◽  
Cartilage Restoration ◽  
History Of ◽  
The Mean

Background: Cell-based cartilage restoration with autologous chondrocyte implantation (ACI) is a safe and effective treatment for symptomatic cartilage lesions. Many patients undergoing ACI have a history of prior surgery, including bone marrow stimulation (BMS). There is mounting evidence that a history of prior BMS may impede healing of the ACI graft. Purpose/Hypothesis: The purpose of this study was to compare the failure rates of primary ACI with ACI after prior BMS. We hypothesized that ACI after BMS would have a significantly higher failure rate (defined as reoperation, conversion to arthroplasty, and/or imaging-based failure) compared with primary ACI. Study Design: Systematic review; Level of evidence, 4. Methods: A literature search was performed by use of PubMed and Embase databases for relevant articles published through October 2, 2020, to identify studies evaluating outcomes and failures rates of ACI after prior BMS in the knee. Results: Included were 11 studies comprising 1479 ACI procedures. The mean age at surgery ranged from 18.3 to 39.1 years, and the mean follow-up ranged from 3 to 20.6 years. All studies reported failure rates. The overall failure rate was significantly higher in the patients who underwent ACI after BMS, at 26.4% compared with 14.8% in the ACI group ( P < .001). Meta-analysis demonstrated an increased risk of failure in patients with a history of prior BMS (log odds ratio = –0.90 [95% confidence interval, –1.38 to –0.42]). Conclusion: This systematic review demonstrated that failure rates were significantly higher for patients treated with ACI after BMS relative to patients undergoing ACI without prior BMS. This finding has important implications when considering the use of BMS for defects that are amenable to cell-based restoration and when determining treatment options after failed BMS. Registration: PROSPERO (CRD42020180387).

Periodic Inspection Optimization of a k-Out-of-n Load-Sharing System

2015 ◽  
Vol 64 (3) ◽  
pp. 1116-1127 ◽  
Author(s):  
Sharareh Taghipour ◽  
Maryam L Kassaei
Keyword(s):  
Load Sharing ◽  
Periodic Inspection
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