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Bibliografie tematiche / Structural valve deterioration

Letteratura scientifica selezionata sul tema "Structural valve deterioration"

Autore: Grafiati

Pubblicato: 15 giugno 2024

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Articoli di riviste sul tema "Structural valve deterioration":

1

Foroutan, Farid, Gordon H. Guyatt, Catherine M. Otto, Reed A. Siemieniuk, Stefan Schandelmaier, Thomas Agoritsas, Per O. Vandvik, Sai Bhagra e Rodrigo Bagur. "Structural valve deterioration after transcatheter aortic valve implantation". Heart 103, n. 23 (6 luglio 2017): 1899–905. http://dx.doi.org/10.1136/heartjnl-2017-311329.

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2

Atkins, B. Zane, e Gabriel S. Aldea. "“Drilling Down” on Structural Valve Deterioration". Journal of the American College of Cardiology 72, n. 5 (luglio 2018): 586. http://dx.doi.org/10.1016/j.jacc.2018.04.080.

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3

Hernandez-Vaquero, Daniel, Rocio Diaz, Isaac Pascual, Jacobo Silva e Cesar Moris. "Considerations When Evaluating Structural Valve Deterioration". Journal of the American College of Cardiology 72, n. 5 (luglio 2018): 586–87. http://dx.doi.org/10.1016/j.jacc.2018.04.081.

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4

Werner, Paul, Jasmin Gritsch, Sabine Scherzer, Christoph Gross, Marco Russo, Iuliana Coti, Alfred Kocher, Guenther Laufer e Martin Andreas. "Structural valve deterioration after aortic valve replacement with the Trifecta valve". Interactive CardioVascular and Thoracic Surgery 32, n. 1 (22 novembre 2020): 39–46. http://dx.doi.org/10.1093/icvts/ivaa236.

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Abstract OBJECTIVES Despite promising short- and mid-term results for durability of the Trifecta valve, contradictory reports of early structural valve deterioration (SVD) do exist. We investigated the incidence of SVD after surgical aortic valve replacement (SAVR) with the Trifecta in our single-centre experience. METHODS Data of 347 consecutive patients (mean age 71.6 ± 9.5 years, 63.4% male) undergoing SAVR with the Trifecta between 2011 and 2017 were analysed. Clinical and echocardiographic reports were obtained with a median follow-up of 41 months (1114 patient years). RESULTS Isolated SAVR was performed in 122 patients (35.2%), whereas 225 patients (64.8%) underwent concomitant procedures. The median EuroSCORE II was 4.0 (0.9; 7.1) and 30-day mortality was 3.7% (n = 13). Kaplan–Meier estimates for the freedom of overall mortality at 1, 5 and 7 years were 88.7 ± 1.7%, 73.7 ± 2.6% and 64.7 ± 4.2%, respectively. SVD was observed in 25 patients (7.2%) with a median time to first diagnosis of 73 months. Freedom of SVD was 92.5 ± 0.9% at 5 years and 65.5 ± 7.1% at 7 years. Thirteen patients underwent reintervention for SVD (6 re-SAVR, 7 valve-in-valve), resulting in a freedom of reintervention for the SVD of 98.5 ± 1.1% at 5 years and 76.9 ± 6.9% at 7 years. CONCLUSIONS We herein report one of the highest rates of SVD after SAVR with the Trifecta. These data indicate that the durability of the prosthesis decreases at intermediate to long-term follow-up, leading to considerable rates of reintervention due to SVD.

5

Kattach, Hassan, Clifford W. Barlow e Sunil K. Ohri. "Structural valve deterioration of a pericardial bioprosthesis". JTCVS Open 9 (marzo 2022): 84–85. http://dx.doi.org/10.1016/j.xjon.2021.10.059.

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6

Sénage, Thomas, Florence Gillaizeau, Thierry Le Tourneau, Basile Marie, Jean-Christian Roussel e Yohann Foucher. "Structural valve deterioration of bioprosthetic aortic valves: An underestimated complication". Journal of Thoracic and Cardiovascular Surgery 157, n. 4 (aprile 2019): 1383–90. http://dx.doi.org/10.1016/j.jtcvs.2018.08.086.

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7

Issa, Issa Farah, Steen Hvitfeldt Poulsen, Farhad Waziri, Christian Torp Pedersen, Per Hostrup Nielsen, Lars Riber, Jordi S. Dahl, Peter Søgaard, Martin Agge Nørgaard e Jacob Eifer Møller. "Structural valve deterioration in the Mitroflow biological heart valve prosthesis". European Journal of Cardio-Thoracic Surgery 53, n. 1 (28 settembre 2017): 136–42. http://dx.doi.org/10.1093/ejcts/ezx321.

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8

Nardi, Paolo, Carlo Bassano, Antonio Pellegrino e Giovanni Ruvolo. "Early structural valve deterioration of the Mitroflow biological valve prosthesis". European Journal of Cardio-Thoracic Surgery 54, n. 1 (29 marzo 2018): 200–201. http://dx.doi.org/10.1093/ejcts/ezy136.

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9

Deutsch, Marcus-André, N. Patrick Mayr, Gerald Assmann, Albrecht Will, Markus Krane, Nicolo Piazza, Sabine Bleiziffer e Ruediger Lange. "Structural Valve Deterioration 4 Years After Transcatheter Aortic Valve Replacement". Circulation 131, n. 7 (17 febbraio 2015): 682–85. http://dx.doi.org/10.1161/circulationaha.114.013995.

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10

Tang, Gilbert H. L., Isaac George e Vinayak N. Bapat. "Structural Valve Deterioration in Surgical Versus Transcatheter Aortic Valve Replacement". Journal of the American College of Cardiology 73, n. 21 (giugno 2019): 2785. http://dx.doi.org/10.1016/j.jacc.2019.02.073.

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Più fonti

Tesi sul tema "Structural valve deterioration":

1

Soquet, Jérôme. "Modulation médicamenteuse des calcifications valvulaires dans un modèle ovin de xénogreffe aortique". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILS061.

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La sténose valvulaire aortique (SVA) est la valvulopathie la plus fréquente et la plus létale dans la population âgée dans les pays à revenu élevé
Aortic stenosis (AS) is the most frequent and the most lethal valvular heart disease in the elderly in high-income countries

2

Šťastný, Miroslav. "Oceňování nemovitostí typu letní tábor". Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-232744.

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Diploma thesis “Property valuation type of summer camp” is focused on recording and valuation of all the immovable property, which are parts and outbuildings of summer camp near the Vranov dam. Theoretical part of this thesis deals with basic terminology and utilized valuation methods. Short locality characterization and relevant real estate market are described in the practical part. Main focus of the practical part is actual valuation of immovable property using methods described in theoretical part. After that, calculated and estimated prices are evaluated and analyzed.

Libri sul tema "Structural valve deterioration":

1

Sobczyk, Eugeniusz Jacek. Uciążliwość eksploatacji złóż węgla kamiennego wynikająca z warunków geologicznych i górniczych. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN, 2022. http://dx.doi.org/10.33223/onermin/0222.

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Hard coal mining is characterised by features that pose numerous challenges to its current operations and cause strategic and operational problems in planning its development. The most important of these include the high capital intensity of mining investment projects and the dynamically changing environment in which the sector operates, while the long-term role of the sector is dependent on factors originating at both national and international level. At the same time, the conditions for coal mining are deteriorating, the resources more readily available in active mines are being exhausted, mining depths are increasing, temperature levels in pits are rising, transport routes for staff and materials are getting longer, effective working time is decreasing, natural hazards are increasing, and seams with an increasing content of waste rock are being mined. The mining industry is currently in a very difficult situation, both in technical (mining) and economic terms. It cannot be ignored, however, that the difficult financial situation of Polish mining companies is largely exacerbated by their high operating costs. The cost of obtaining coal and its price are two key elements that determine the level of efficiency of Polish mines. This situation could be improved by streamlining the planning processes. This would involve striving for production planning that is as predictable as possible and, on the other hand, economically efficient. In this respect, it is helpful to plan the production from operating longwalls with full awareness of the complexity of geological and mining conditions and the resulting economic consequences. The constraints on increasing the efficiency of the mining process are due to the technical potential of the mining process, organisational factors and, above all, geological and mining conditions. The main objective of the monograph is to identify relations between geological and mining parameters and the level of longwall mining costs, and their daily output. In view of the above, it was assumed that it was possible to present the relationship between the costs of longwall mining and the daily coal output from a longwall as a function of onerous geological and mining factors. The monograph presents two models of onerous geological and mining conditions, including natural hazards, deposit (seam) parameters, mining (technical) parameters and environmental factors. The models were used to calculate two onerousness indicators, Wue and WUt, which synthetically define the level of impact of onerous geological and mining conditions on the mining process in relation to: —— operating costs at longwall faces – indicator WUe, —— daily longwall mining output – indicator WUt. In the next research step, the analysis of direct relationships of selected geological and mining factors with longwall costs and the mining output level was conducted. For this purpose, two statistical models were built for the following dependent variables: unit operating cost (Model 1) and daily longwall mining output (Model 2). The models served two additional sub-objectives: interpretation of the influence of independent variables on dependent variables and point forecasting. The models were also used for forecasting purposes. Statistical models were built on the basis of historical production results of selected seven Polish mines. On the basis of variability of geological and mining conditions at 120 longwalls, the influence of individual parameters on longwall mining between 2010 and 2019 was determined. The identified relationships made it possible to formulate numerical forecast of unit production cost and daily longwall mining output in relation to the level of expected onerousness. The projection period was assumed to be 2020–2030. On this basis, an opinion was formulated on the forecast of the expected unit production costs and the output of the 259 longwalls planned to be mined at these mines. A procedure scheme was developed using the following methods: 1) Analytic Hierarchy Process (AHP) – mathematical multi-criteria decision-making method, 2) comparative multivariate analysis, 3) regression analysis, 4) Monte Carlo simulation. The utilitarian purpose of the monograph is to provide the research community with the concept of building models that can be used to solve real decision-making problems during longwall planning in hard coal mines. The layout of the monograph, consisting of an introduction, eight main sections and a conclusion, follows the objectives set out above. Section One presents the methodology used to assess the impact of onerous geological and mining conditions on the mining process. Multi-Criteria Decision Analysis (MCDA) is reviewed and basic definitions used in the following part of the paper are introduced. The section includes a description of AHP which was used in the presented analysis. Individual factors resulting from natural hazards, from the geological structure of the deposit (seam), from limitations caused by technical requirements, from the impact of mining on the environment, which affect the mining process, are described exhaustively in Section Two. Sections Three and Four present the construction of two hierarchical models of geological and mining conditions onerousness: the first in the context of extraction costs and the second in relation to daily longwall mining. The procedure for valuing the importance of their components by a group of experts (pairwise comparison of criteria and sub-criteria on the basis of Saaty’s 9-point comparison scale) is presented. The AHP method is very sensitive to even small changes in the value of the comparison matrix. In order to determine the stability of the valuation of both onerousness models, a sensitivity analysis was carried out, which is described in detail in Section Five. Section Six is devoted to the issue of constructing aggregate indices, WUe and WUt, which synthetically measure the impact of onerous geological and mining conditions on the mining process in individual longwalls and allow for a linear ordering of longwalls according to increasing levels of onerousness. Section Seven opens the research part of the work, which analyses the results of the developed models and indicators in individual mines. A detailed analysis is presented of the assessment of the impact of onerous mining conditions on mining costs in selected seams of the analysed mines, and in the case of the impact of onerous mining on daily longwall mining output, the variability of this process in individual fields (lots) of the mines is characterised. Section Eight presents the regression equations for the dependence of the costs and level of extraction on the aggregated onerousness indicators, WUe and WUt. The regression models f(KJC_N) and f(W) developed in this way are used to forecast the unit mining costs and daily output of the designed longwalls in the context of diversified geological and mining conditions. The use of regression models is of great practical importance. It makes it possible to approximate unit costs and daily output for newly designed longwall workings. The use of this knowledge may significantly improve the quality of planning processes and the effectiveness of the mining process.

Capitoli di libri sul tema "Structural valve deterioration":

1

Yankah, Charles A., M. Pasic, Henryk Siniawski, J. Stein, C. Detschades, A. Unbehaun, N. Solowjowa, S. Buz, Y. Weng e Roland Hetzer. "Replacement of bioprostheses after structural valve deterioration". In Aortic Root Surgery, 503–19. Heidelberg: Steinkopff, 2010. http://dx.doi.org/10.1007/978-3-7985-1869-8_37.

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2

Peng, Hua, e Yixin He. "Analysis of Subway Braking Performance Based on Fuzzy Comprehensive Evaluation Method". In Proceeding of 2021 International Conference on Wireless Communications, Networking and Applications, 805–12. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-2456-9_81.

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AbstractIn the process of subway operation, the braking system is a complex system, and its state detection is for high data accuracy and state positioning accuracy According to the structure of the braking system and the principle of the braking method, the basic braking performance parameters of the system are analyzed, combined with the abnormal state of the subway brake cylinder pressure data, the braking process is divided into two stages: brake cylinder pressure establishment and peak stability. And define the six characteristic parameters of 90% brake cylinder pressure establishment time, special slope period time, stable pressure value, stable pressure standard deviation, maximum value and minimum value. Aiming at the braking process performance, a data mining theory is proposed, and software based on the fuzzy comprehensive evaluation method is written to analyze the deterioration of the braking performance of subway vehicles. The actual on-board data is used as an example to verify the reliability of the theory.

3

Boodhwani, Munir, e Gebrine El Khoury. "Aortic valve repair". In Core Concepts in Cardiac Surgery, 73–96. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198735465.003.0004.

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Aortic valve replacement remains the gold standard for the treatment of severe aortic valve disease. Techniques for valve repair are emerging as a feasible alternative to valve replacement in selected patients. Advantages include potential reduction in the risks of prosthesis-related complications such as thromboembolism, endocarditis, anticoagulant-related hemorrhage, and reoperation due to structural valve deterioration. In this chapter, the key features of aortic valve and root anatomy, an approach to valve assessment and lesion classification, a demonstration of commonly used reparative techniques for aortic valve repair, and outcomes are reviewed. Furthermore, it also examines the outcomes of aortic valve repair in unselected cohorts, as well as distinct subsets of patients undergoing aortic valve preservation and repair.

4

Navaratnarajah, Manoraj, Amit Modi e Sunil Ohri. "Valve-in-Valve Transcatheter Aortic Valve Replacement: Challenges for Now and the Future". In Cardiology and Cardiovascular Medicine. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.112764.

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The recent years have seen a huge expansion in the number of bioprostheses implanted, and this number is likely to increase further in the future. This is likely to lead to a pandemic of patients requiring reoperation/re-intervention for structural deterioration of the valve. Valve-in-valve transcatheter aortic valve replacement (ViV-TAVR) has become a safe and effective alternative to redo aortic valve surgery and has gained approval for use in high-risk patients with prohibitive operative risk. ViV-TAVR is a complex procedure requiring rigorous planning, technical expertise and patient anatomical appreciation. In this chapter, we examine the evidence supporting the use of ViV-TAVR along with the primary technical issues surrounding this procedure such as: elevated postprocedural gradients, coronary obstruction and valve-related thrombosis. TAVR use is also expanding towards an increasingly young patient profile with extended life expectancy, likely to outlive the implanted bioprosthesis. We therefore also examine the huge current challenge of establishing what is the best lifetime strategy for the management of aortic valve disease in younger patients.

5

_adauskiene, J., E. Monstvilas e V. Stankevicius. "The effect of thermal resistance value to the external deterioration due to climate impact". In Improvement of Buildings' Structural Quality by New Technologies, 579–84. Taylor & Francis, 2005. http://dx.doi.org/10.1201/9780203970843.ch67.

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6

"The effect of thermal resistance value to the external deterioration due to climate impact". In Improvement of Buildings' Structural Quality by New Technologies, 591–98. CRC Press, 2005. http://dx.doi.org/10.1201/9780203970843-69.

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7

Oncioiu, Ionica, Traian Ovidiu Calotă e Alin Eliodor Tănase. "Manipulating Business Performances by Creative Accounting". In Encyclopedia of Organizational Knowledge, Administration, and Technology, 24–34. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-3473-1.ch003.

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The dual nature of creative accounting has been intensely debated since its emergence in the Anglo-Saxon economies. The lack of a common accounting language, different accounting systems at international level, applied in different languages, international legislation harmonized more or less correctly, amidst a turbulent economic environment, left room for multiple interpretations and meanings. This chapter presents the advantages of fair value in manipulating business performances by creative accounting, but there are voices that are challenging this concept because of its volatility and tendency to subjectivism, and also manipulating the models used to evaluate balance-sheet structures or profit and loss account. The results show that fair value was introduced by accounting norms in response to the deterioration of confidence in the financial statements and targets a new system for assessing the entity's assets and liabilities.

8

Oncioiu, Ionica, Cristina Maria Ștefan, Valentin Radu e Georgiana Burlacu. "The Effect of Accounting Manipulation on the Business Performances". In Management Accounting Standards for Sustainable Business Practices, 168–77. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-0178-8.ch008.

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The dual nature of creative accounting has been intensely debated since its emergence in the Anglo-Saxon economies. The lack of a common accounting language, different accounting systems at international level, applied in different languages, international legislation harmonized more or less correctly, amidst a turbulent economic environment, left room for multiple interpretations and meanings. This chapter presents the advantages of fair value in manipulating business performances by creative accounting, but there are voices that are challenging this concept because of its volatility and tendency to subjectivism, and also manipulating the models used to evaluate balance-sheet structures or profit and loss account. The results show that fair value was introduced by accounting norms in response to the deterioration of confidence in the financial statements and targets a new system for assessing the entity's assets and liabilities.

9

Wu, Yushan, Yanfei Xu, Chuan Qin e Mingyue Ding. "Metal-Organic Frameworks and Their Derived Structures for Biomass Upgrading". In Advanced Catalysts Based on Metal-organic Frameworks (Part 1), 184–255. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815079487123010006.

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Biomass valorization is receiving increasing attention over the past years with the consumption of traditional fossil fuels as well as the deterioration of the global environment. The transformation of biomass into highly value-added chemicals and important feedstocks will be of keen interest and great impact. The conversion process of biomass requires efficient and durable catalysts with high selectivity and stable structures. This chapter focuses on the employment of metal-organic frameworks (MOFs), MOF composites (metal, metal oxide, or polyoxometalates combined with MOFs), and MOF-derived materials (carbon, carbon-supported metal or metal oxide by using MOF as precursors) as solid catalysts for the upgrading of biomass into important fine chemicals. First, we will give a short introduction of biomass and MOFs, and then the brief biomass valorization reactions by MOFs and MOF-based catalysts based on the types of substrates. The last segment is summary of the state of the art, challenges, as well as prospects of MOFs and MOFs-derived structures for biomass transformation.

10

Norekvål, Tone M., Britt Borregaard, Tina B. Hansen, Trine B. Rasmussen e Sandra B. Lauck. "Care of the patient with valvular heart disease". In ESC Textbook of Cardiovascular Nursing, a cura di Catriona Jennings, Felicity Astin, Donna Fitzsimons, Ekaterini Lambrinou, Lis Neubeck e David R. Thompson, 215–40. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780198849315.003.0008.

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Valvular heart disease is associated with significant mortality and morbidity, increased symptoms, and poor quality of life, as well as high rates of hospital readmission. There has been a rapid emergence in the past decade of minimally invasive transcatheter options for patients for high surgical risk patients with valve disease. Acquired valvular heart disease is primarily a disease of ageing and requires an understanding of frailty, as well as pathophysiology, screening, and clinical implications. This is a core competency of cardiovascular nurses who provide care to patients with complex valvular heart disease and are also an integral part of a team-based approach which aims to leverage the strengths and skills of its members to optimize the safety and quality of patient care. Endocarditis is an infection of the endocardial surface involving the heart valves and/or surrounding structures typically caused by bacteria. Close monitoring for early signs of disease progression, inadequate infection control, and complications is essential to prevent clinical deterioration. Patients recovering from infective endocarditis will often have been physically inactive for weeks or months due to diagnostic delay, symptom burden, long-term hospitalization, and postsurgical restrictions. The implications of changes in haemodynamics, the trajectory of heart failure, and the variation in clinical presentation across age groups and pathologies create unique challenges. Effective nursing interventions have the potential to optimize outcomes and support patients and their family.

Atti di convegni sul tema "Structural valve deterioration":

1

Sun, Wei, Hengchu Cao, Jim Davidson e Michael Sacks. "Biomechanical Simulations of Bioprosthetic Heart Valve Deformations". In ASME 2006 Frontiers in Biomedical Devices Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/nanobio2006-18047.

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Previous research has suggested that the structural deterioration in porcine bioprosthetic heart valves (BHV) may be correlated with the regions of high tensile and bending stresses acting on the leaflets during opening and closing[1, 2]. Stress concentrations within the cusp can either directly accelerate tissue structural fatigue damage, or initiate calcification by causing structural disintegration, enabling multiple pathways of calcification that can lead to valve failure[3,4]. In the case of bovine pericardial heart valve prostheses, structural failure of the leaflets is rare but calcification has been observed. Although details of the process are unclear, it is generally assumed that the design of the pericardial valve, which gives a stress-reduced state of the leaflets, is likely to provide improved performance in long-term applications.

2

Sierad, Leslie N., e Dan Simionescu. "In Vitro Testing of Living Aortic Heart Valves Using a Pulsatile Bioreactor". In ASME 2008 3rd Frontiers in Biomedical Devices Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/biomed2008-38063.

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Valvular heart disease results in approximately 275,000 valve replacement procedures performed annually worldwide. Structural deterioration, calcification, tissue overgrowth, and thromboembolism frequently lead to abnormal tissue stiffness levels that contribute to the failure of native heart valves. While many treatment alternatives exist, understanding the factors that regulate the activity of heart valve cells is critical for circumventing pathological heart valve fibrosis and engineering improved biologically active heart valve replacements.

3

Argento, Giulia, Cees W. J. Oomens e Frank P. T. Baaijens. "Optimal Boundary Conditions for the Multi-Scale Finite Element Analysis of Fibrous Scaffolds for Heart Valve Tissue Engineering". In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53238.

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Although existing valve prostheses generally have resulted in enhanced survival and quality of life, they have serious drawbacks that limit their long-term efficacy. These include thrombo-embolic complications requiring lifelong anticoagulation in case of mechanical valves, limited durability due to calcification and structural failure in case of bioprostheses and structural deterioration and shortage of donor material when using a homograft. In addition, the inability to grow restricts the application of currently available prostheses in pediatric patients. Heart valve tissue engineering (TE) is a promising alternative to create living valves that may have the capacity to grow and remodel. The traditional TE approach requires the growth of tissue on a scaffold in a bioreactor before implantation (1).

4

Upadhyay, Kamal, Rui Yu, Hua Zhou e Huayong Yang. "The CFD Analysis of Cavitation Erosion and Structural Optimization for an Unloading Valve". In ASME 2021 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fedsm2021-65695.

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Abstract The unloading valve is selected as the key part of pressure control and overload protection system in the emulsion pump station (EPS). However, severe cavitation erosion occurs on the inner wall of the valve sleeve located in a downstream outlet, which leads to the performance deterioration, instability, and even failure of the unloading valve. This paper aims to reduce the cavitation phenomenon by optimizing the structure of the spool and improving the streamline direction of the unloading valve. The change in internal structure can reduce cavitation cloud formation along with the internal mechanism of the valve. The working conditions of its flow versus time-dependent data’s are obtained by AMESim, and considered as the boundary condition in Fluent. In addition, the changes in flow behavior and input data’s are analyze and validate before the structural is optimized. After an analysis, the variations in velocities and vapor phase, indicating the higher in pressure drop at its minimum size of valve opening and further consideration for design and development stages. Two innovative structures of valve throttling spool are proposed as a simplified design stage and then carefully curved based on internal geometry to uniformly distribute the velocity vector and streamlines. Subsequently, the post-CFD results reveal the presence of factors affecting properties such as pressure loss, high velocity in the outlets, and concentrated of the vapor volume fraction are decreased under the modified throttling structure and effectively lowers the intensity of cavitation phenomenon.

5

Mamdooh, H., F. Pollari, I. Großmann, M. Claes, V. Zujs e T. Fischlein. "Risk Factors for Structural Valve Deterioration of the Aortic Sutureless Prosthesis in a 10-Year Follow-up Study". In 51st Annual Meeting of the German Society for Thoracic and Cardiovascular Surgery (DGTHG). Georg Thieme Verlag KG, 2022. http://dx.doi.org/10.1055/s-0042-1742871.

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6

Claiborne, Thomas E., Michalis Xenos, Jawaad Sheriff, Dinesh Peter, Yared Alemu, Yasushi Kato, Leonard Pinchuk, Shmuel Einav, Jolyon Jesty e Danny Bluestein. "Development and Optimization of a Novel Polymeric Prosthetic Heart Valve Using the Device Thrombogenicity Emulation (DTE) Methodology". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80186.

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Calcific aortic valve disease (CAVD) is the most common and life threatening form of valvular heart disease, characterized by stenosis and regurgitation, which is currently treated at the symptomatic end-stages via open-heart surgical replacement of the diseased valve with typically either a xenograft tissue valve or mechanical heart valve. These options offer the clinician a choice between structural valve deterioration and anticoagulant therapy respectively, effectively replacing one disease with another [1]. Polymeric heart valves (PHV) offer the promise of reducing or eliminating these complications [2] and may be efficacious for patients who cannot tolerate cardiothoracic surgery by using instead transcatheter valve implantation (TAVI) [3], where there is evidence that tissue valves are damaged during implantation [4], and in pulsatile circulatory support devices such as the SynCardia Total Artificial Heart. But development of PHVs has been slow due to the lack of sufficiently durable and biocompatible formulations.

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Hennessy, T., D. Chieng, K. Ireland, G. Yong e G. Hillis. "44 Long term echocardiographic follow up post transcatheter aortic valve implantation (TAVI) to assess for structural valve deterioration (SVD) and bioprosthetic valve failure (BVF): a single centre prospective study". In Irish Cardiac Society Annual Scientific Meeting & AGM, Thursday October 17th – Saturday October 19th 2019, Galway, Ireland. BMJ Publishing Group Ltd and British Cardiovascular Society, 2019. http://dx.doi.org/10.1136/heartjnl-2019-ics.44.

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Dann, Markus R., e Marc A. Maes. "Value of Information-Based Inspection Planning using a Population Approach". In IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/guimaraes.2019.1808.

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Abstract (sommario):

<p>A value-of-information analysis is proposed that is tailored toward the inspection planning of damaged and deteriorating engineering systems where defect-specific matching and individual deterioration growth analysis are not computationally feasible. Defects and/or damage are treated using a population perspective with a probabilistic formulation of the evolution of the number of defects and the extent of deterioration rather than the modelling of individual defects. Measurement errors associated with inspection such as detectability, false calls, and sizing errors are considered to relate the observed to the actual state of structural deterioration. The population- based deterioration model is embedded in a Bayesian pre-posterior analysis to assess the value of information that is achieved by performing an inspection. Applications include the inspection planning of critical components of structural systems such as bridges, tunnels, pipelines, and offshore structures. The proposed analysis is illustrated using a numerical example where the long- term cost benefit of implementing an inspection scheme is determined.</p>

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ARCIERI, GIACOMO, CYPRIEN HOELZL, OLIVER SCHWERY, DANIEL STRAUB, KONSTANTINOS G. PAPAKONSTANTINOU e ELENI CHATZI. "A COMPARISON OF VALUE-BASED AND POLICY-BASED REINFORCEMENT LEARNING FOR MONITORINGINFORMED RAILWAY MAINTENANCE PLANNING". In Structural Health Monitoring 2023. Destech Publications, Inc., 2023. http://dx.doi.org/10.12783/shm2023/37015.

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Optimal maintenance planning for railway infrastructure and assets forms a complex sequential decision-making problem. Railways are naturally subject to deterioration, which can result in compromised service and increased safety risks and costs. Maintenance actions ought to be proactively planned to prevent the adverse effects of deterioration and the associated costs. Such predictive actions can be planned based on monitoring data, which are often indirect and noisy, thus offering an uncertain assessment of the railway condition. From a mathematical perspective, this forms a stochastic control problem under data uncertainty, which can be cast as a Partially Observable Markov Decision Process (POMDP). In this work, we model the real-world problem of railway optimal maintenance planning as a POMDP, with the problem parameters inferred from real-world monitoring data. The POMDP model serves to infer beliefs over a set of hidden states, which aim to capture the evolution of the underlying deterioration process. The maintenance optimization problem is here ultimately solved via the use of deep Reinforcement Learning (RL) techniques, which allow for a more flexible and broad search over the policy space when compared to classical POMDP solution algorithms. A comparison of value-based and policy-based RL methods is also offered, which exploit deep learning architectures to model either action-value functions (i.e., the expected returns from an action-state pair) or directly the policy. Our work shows how this complex planning problem can be effectively solved via deep RL to derive an optimized maintenance policy of railway tracks, demonstrated on real-world monitoring data, and offers insights into the solution provided by different classes of RL algorithms.

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Karadeniz, H. "Uncertainty Modelling and Fatigue Reliability Calculation of Offshore Structures With Deteriorated Members". In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51403.

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This paper presents formulations and procedure of an efficient calculation of stress spectra and fatigue damage of offshore structures with deteriorated members in the uncertainty space. Calculation modeling of member deteriorations is represented by equivalent spring systems, which can be determined on basis of damage detection and stiffness degradation, with a deterioration uncertainty parameter. Redistributions of the member and system stiffness matrices and the load vectors are expressed in incremental (decremental) forms. The updated system stiffness-matrix is sated in terms of stiffness- and deterioration-uncertainties and the updated system load-vector is stated in terms of deterioration- and loading-uncertainties. Using the Neumann expansion solution technique, the inversion of the updated system stiffness matrix is expressed in terms of uncertainty parameters so that the reliability iteration can be performed without requiring repetitive inversion of the stiffness matrix. The deterioration- and uncertainty-update of the stiffness matrix requires resolution of the eigenvalue problem. This problem is reformulated in terms of uncertainty variables and an efficient solution algorithm is presented. An extra uncertainty parameter is used in structural transfer functions to represent damping uncertainties. Having expressed wave forces as functions of uncertainty variables, formulations of transfer functions of displacements and member internal forces are presented in the uncertainty space, which enable the reliability calculation to be efficient and fast. Apart from uncertainties of structural and loading origins, uncertainties arising from environmental origin, which appear in the spectral-analysis, are summarized. These are related to the modeling of random waves and wave-current interactions as well as to the long-term probability-distribution model of the significant wave height. Uncertainties in SCF, damage model (S-N line), non-narrowness of the stress process, long-term probability distribution of sea states and in the damage at which failure occurs (reference damage) are considered in fatigue-related uncertainties. An example is presented to demonstrate the application of the approximate analysis procedure to the mean value response analysis of deteriorated structures.