Optimum Maintenance Policy with Inspection by Semi-Markov Decision Processes

Ge, Haifeng; Tomasevicz, Curtis L.; Asgarpoor, Sohrab

doi:10.1109/naps.2007.4402363

Cited by 15 publications

(6 citation statements)

References 13 publications

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“…Markov decision processes (MDPs) have commonly been leveraged for condition-based maintenance due to their ability to characterize multiple maintenance actions and multiple degradation states (Papakonstantinou & Shinozuka 2014b,c). In particular, POMDPs have been utilized in the optimal maintenance of numerous systems (eg., (Byon et al 2010, Ge et al 2007, Ghandali et al 2020, Papakonstantinou & Shinozuka 2014a, Zhang & Revie 2017, Zouch et al 2011). More recently, Morato et al (2022) proposed integrating Bayesian networks with POMDPs to provide a joint framework for inspection and maintenance planning.…”

Section: Literature Reviewmentioning

confidence: 99%

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas ^1,2, Fotios Spyropoulos^1,2,Helen Christou ^1,2¹Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA ²Harvard Medical School, Boston, MA 02215, USA

2022

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Background PAH is a devastating and incurable disease characterized by abnormal pulmonary vascular phenotypes and progressive right ventricular failure, but the underlying mechanisms are incompletely understood. There is an urgent need of new therapeutic approaches, and a better understanding of disease pathogenesis is essential in identifying novel pathways that can be therapeutically targeted. Stress granules (SGs) are small intracellular structures that form in response to stress and contain mRNA molecules and mRNA‐binding proteins. These granules allow cells to temporarily halt translation by “parking” or sequestering certain mRNAs in a protected zone (the stress granule) and this allows the cells to survive in conditions of stress. The role of SGs in abnormal vascular and cardiac homeostasis in PAH is not known. Hypotheses We hypothesized that increased SG formation may contribute to both abnormal vascular cellular phenotypes and cardiac failure in human and experimental PAH. Further, we examined whether treatment with the carbonic anhydrase Acetazolamide (ACTZ) which is known to ameliorate experimental PAH, would alter SG tissue abundance in the lungs and heart. Methods We used the adult rat (Sprague Dawley) sugen/hypoxia (Su/Hx) model of severe pulmonary hypertension and studied tissue sections from lungs, heart and skeletal muscle as well as isolated primary pulmonary artery smooth muscle cells (PASMCs). We also used PASMCs from patients with PAH. We applied a combination of immunofluorescence and protein expression studies as well as drug (ACTZ) treatment and in vitro induction of oxidative stress (arsenite) to assess SG formation and SG related markers in experimental PAH and the effect of ACTZ. Results We have discovered that PASMCs from patients with PAH have a higher number of stress granules in response to oxidative stress than cells from normal individuals. We also found that PASMCs from a preclinical model of PAH (Sugen/Hypoxia) have more stress granules and increased SG components in response to oxidative stress compared to normal animals. Further, we found that treatment of PASMCs with ACTZ resulted in lower number of stress granules after cell stress. In addition, we found increased G3BP1 (key component of SG assembly) puncta in alveoli and bronchi and sarcoplasmic G3BP1 puncta in cardiac and soleus muscles from the rat sugen/hypoxia (Su/Hx) model compared to controls and with ACTZ treatment. Conclusions We conclude that there is increased SG formation in PASMCs and tissues in experimental PAH and acetazolamide inhibits stress granule assembly in response to oxidative stress. Further studies are needed to define the role of SG in disease pathogenesis, and evaluate whether targeting stress granules may be effective in restoring normal cellular function and improving PAH.

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Section: Literature Reviewmentioning

confidence: 99%

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas ^1,2, Fotios Spyropoulos^1,2,Helen Christou ^1,2¹Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA ²Harvard Medical School, Boston, MA 02215, USA

2022

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“…of the matrix ( ) Q t are the conditional probabilities of the process of transition from the state i S to the state j S , within a time period of not more than t , specified according to the formula (11). They depend on the distribution of random variables, namely the process durations in the distinguished states:…”

Section: Basic Characteristicsmentioning

confidence: 99%

“…Alternative methods are used in such a case, e.g. reliable phase diagrams proposed by Lu et al [24] or Dong et al [9], as well as Markov processes [11,16,34], which are particularly popular in the readiness assessment. In the literature one can find models describing single means of transport, e.g.…”

Section: Introductionmentioning

confidence: 99%

Forecasting the readiness of special vehicles using the semi-Markov model

Borucka¹,

Niewczas²,

Hasilová³

2019

Eksploatacja i Niezawodność – Maintenance and Reliability

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“…However, in this paper, a semi-Markov process with consideration of different types of inspection, maintenance, and faults is used to model aging equipment. Detailed comparisons, including several case studies, are presented in [29].…”

Section: A Aging and Maintenance Of Power Equipmentmentioning

confidence: 99%

Reliability and Maintainability Improvement of Substations With Aging Infrastructure

Ge¹,

Asgarpoor

2012

IEEE Trans. Power Delivery

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The increasing size, aging equipment, and complexity of power systems, coupled with present day financial constraints, have made the use of probabilistic methods and reliability indices a necessity for maintaining continuity and quality of service to customers. Proper maintenance-related decisions should address all of these issues to improve system reliability while meeting limited budget constraints. This paper proposes algorithms that enable system-level reliability assessment with detailed modeling of maintenance for aging equipment. Stochastic-based reliability modeling of substations with aging equipment is presented, which enables the study of equipment aging, failures, and maintenance and their effect on substation-level availability and frequency of failure. Several case studies are provided which describe optimization of maintenance activities and the impact on maximum substation reliability. The algorithms provide a valuable tool for processing detailed models of aging equipment and maintenance of individual pieces in system reliability assessment applications. These algorithms are consistent with existing reliability models and are capable of being integrated into utility asset-management programs.

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Optimum Maintenance Policy with Inspection by Semi-Markov Decision Processes

Cited by 15 publications

References 13 publications

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas ^1,2, Fotios Spyropoulos^1,2,Helen Christou ^1,2¹Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA ²Harvard Medical School, Boston, MA 02215, USA

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas ^1,2, Fotios Spyropoulos^1,2,Helen Christou ^1,2¹Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA ²Harvard Medical School, Boston, MA 02215, USA

Forecasting the readiness of special vehicles using the semi-Markov model

Reliability and Maintainability Improvement of Substations With Aging Infrastructure

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Optimum Maintenance Policy with Inspection by Semi-Markov Decision Processes

Cited by 15 publications

References 13 publications

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas 1,2, Fotios Spyropoulos1,2,Helen Christou 1,21Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA 2Harvard Medical School, Boston, MA 02215, USA

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas 1,2, Fotios Spyropoulos1,2,Helen Christou 1,21Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA 2Harvard Medical School, Boston, MA 02215, USA

Forecasting the readiness of special vehicles using the semi-Markov model

Reliability and Maintainability Improvement of Substations With Aging Infrastructure

Contact Info

Product

Resources

About

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas ^1,2, Fotios Spyropoulos^1,2,Helen Christou ^1,2¹Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA ²Harvard Medical School, Boston, MA 02215, USA

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas ^1,2, Fotios Spyropoulos^1,2,Helen Christou ^1,2¹Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA ²Harvard Medical School, Boston, MA 02215, USA