Coupling characteristic analysis of ship shafting design parameters and research on multidisciplinary design optimization

In the design process of traditional ship shafting, the design quality is generally hard to get guaranteed for the lack of discipline coupling. In this paper, Multidisciplinary Design Optimization (MDO) is innovatively introduced to ensure design quality. Multidisciplinary decomposition of shafting can help to construct the MDO model of ship shafting based on multidisciplinary feasibility method. Then the sub-discipline model of shifting design can be further established, including calibration neutron discipline model, whirling vibration model, and dynamic stiffness of radial oil film bearing model. Collaborative operation is implemented by the multidisciplinary model of shifting to obtain the experimental results. Based on Radial Basis Function (RBF) neural network, the responsive surfaces of variable, bearing load, and support stiffness can be constructed, in the meanwhile the dynamic stiffness decoupling of vibration model can be obtained. Fireworks algorithm is used to establish multidisciplinary optimization of seven-dimensional design variable. The results show that MDO helps improve the quality of shafting alignment and whirling vibration. The work in present paper also provides insight for the future optimization of research methods, design quality, and engineering experiments

Electrophysiologic assessment of (central) auditory processing disorder in children with non-syndromic cleft lip and/or palate

Session 5aPP - Psychological and Physiological Acoustics: Auditory Function, Mechanisms, and Models (Poster Session)Cleft of the lip and/or palate is a common congenital craniofacial malformation worldwide, particularly non-syndromic cleft lip and/or palate (NSCL/P). Though middle ear deficits in this population have been universally noted in numerous studies, other auditory problems including inner ear deficits or cortical dysfunction are rarely reported. A higher prevalence of educational problems has been noted in children with NSCL/P compared to craniofacially normal children. These high level cognitive difficulties cannot be entirely attributed to peripheral hearing loss. Recently it has been suggested that children with NSCLP may be more prone to abnormalities in the auditory cortex. The aim of the present study was to investigate whether school age children with (NSCL/P) have a higher prevalence of indications of (central) auditory processing disorder [(C)APD] compared to normal age matched controls when assessed using auditory event-related potential (ERP) techniques. School children (6 to 15 years) with NSCL/P and normal controls with matched age and gender were recruited. Auditory ERP recordings included auditory brainstem response and late event-related potentials, including the P1-N1-P2 complex and P300 waveforms. Initial findings from the present study are presented and their implications for further research in this area —and clinical intervention—are outlined. © 2012 Acoustical Society of Americapublished_or_final_versio

Визначення навантаження, що дiє на валопровiд судна при його русi в умовах iнтенсивного нерегулярного хвилювання

Урсолов, О. І. Визначення навантаження, що дiє на валопровiд судна при його русi в умовах iнтенсивного нерегулярного хвилювання : дис. … д-ра філос. : 135 / О. І. Урсолов ; наук. кер. В. О. Нєкрасов ; НУК. – Миколаїв, 2020. – 287 с.Урсолов О. I. Визначення навантаження, що дiє на валопровiд судна при його русi в умовах iнтенсивного нерегулярного хвилювання. – Квалiфiкацiйна наукова праця на правах рукопису. Дисертацiя на здобуття наукового ступеня доктора фiлософiї за спецiальнiстю 135 – суднобудування. – Нацiональний унiверситет кораблебудування iменi адмiрала Макарова, Миколаїв, 2020. У разi вiдмови валопроводу у процесi експлуатацiї, судно втрачає хiд та керованiсть, що може призвести до перекидання в умовах хвилювання. З iншого боку, поломки пов’язанi з валопроводом, призводять до втрати прибутку судновласника або втрати можливостi виконувати бойову задачу, а також до великих додаткових витрат на ремонт. Бiльш точнi моделi роботи суднового валопроводу та розрахунковi схеми його напружено-деформованих станiв дозволять передбачати можливi ризики майбутньої експлуатацiї валопроводу та уточнювати його конструктивнi розмiри при проектуваннi судна або параметри центрування на iснуючих суднах. Особливо актуальною ця проблема є у зв’язку з тим, що режими роботи валопроводу в умовах хитавицi судна на хвилях, є найменш вивченими на даний час. Таким чином, актуальнiсть дисертацiйного дослiдження визначається: 1. Необхiднiстю вдосконалення моделей суднових валопроводiв для розрахункiв параметрiв їх центрування на тихiй водi та роботи в умовах хитавицi суден. 2. Необхiднiстю розробки комплексного розрахункового методу оцiнювання впливу хитавицi на сумiсну роботу системи судно–валопровiд. 3. Необхiднiстю проведення комплексних дослiджень впливу хитавицi судна на роботу валопроводу з метою визначення навантаження, яке дiє на валопровiд. Метою дисертацiйної роботи є розробка методу визначення навантажень, якi дiють на валопровiд при сумiснiй роботi системи судно–валопровiд в умовах руху судна на iнтенсивному нерегулярному хвилюваннi. Наукова новизна отриманих результатiв полягає у наступному. 1. Вперше на основi використання методiв теорiї корабля, будiвельної механiки корабля та гiдродинамiчної теорiї змащення розроблено комплексну модель динамiки системи судно–валопровiд при русi судна на хвилюваннi, яка враховує дiючi на валопровiд гiдродинамiчнi сили на гребному гвинтi, iнерцiйнi сили вiд хитавицi судна, сили вiд деформування корпусу судна на хвилях та еласто-гiдродинамiчне змащення в пiдшипниках гребного вала. 2. Вперше на основi отриманої моделi функцiонування системи судно–валопровiд розроблено комплексний метод розрахунку дiючих на валопровiд статичних та динамiчних навантажень, якi необхiдно враховувати на стадiях проектування валопроводу та вибору параметрiв його центрування. 3. На основi методу скiнченних елементiв удосконалено метод розрахунку компонентiв НДС при статичному згинаннi суднового валопроводу, пiдшипники якого представленi односторонньою неоднорiдною нелiнiйною змiщуваною пружною основою, що дозволило врахувати довжину, зазор, деформування та змiщення пiдшипникiв. 4. На основi використання методiв скiнченних елементiв та оптимiзацiї удосконалено метод розрахунку компонентiв НДС при згинаннi суднового валопроводу з урахуванням еласто-гiдродинамiчного змащення у всiх пiдшипниках, що дозволило уточнити умови його роботи. 5. Отримало подальший розвиток моделювання пружної основи пiдшипника методом скiнченних елементiв, за допомогою якого узагальнено вирази для матрицi жорсткостi стержневого скiнченного елемента пружної основи Вiнклера, що дозволило врахувати змiну коефiцiєнта жорсткостi вздовж пiдшипника. 6. На основi узагальнення та розширення виразiв для релаксацiї отримав подальший розвиток метод релаксацiї послiдовних наближень, що дозволило забезпечити надiйну збiжнiсть нелiнiйних розрахункiв суднового валопроводу. Теоретичне значення дослiдження полягає у розробцi комплексної математичної моделi функцiонування суднового валопроводу та узагальненого методу визначення дiючих на нього навантажень як при вiдсутностi руху судна, так i при його ходi на тихiй водi та в умовах iнтенсивного регулярного i нерегулярного хвилювання. Практичне значення одержаних результатiв полягає у наступному. 1. Розробленi методи розрахунку компонентiв НДС при згинаннi суднового валопроводу у статичних i динамiчних умовах навантаження можуть бути використанi для бiльш точних розрахункiв його центрування. 2. Розроблена модель роботи валопроводу при русi судна на нерегулярних хвилях може бути використана для оцiнювання компонентiв НДС при згинаннi валопроводу з метою урахування небажаних явищ, якi потребують змiни його конструктивних та технологiчних параметрiв. 3. Побудованi залежностi можуть бути використанi для оцiнювання впливу хитавицi судна на навантаження, що дiють на валопровiд. 4. Розроблений скiнченний елемент пружної основи з параболiчною залежнiстю коефiцiєнта жорсткостi за довжиною може бути застосований для бiльш точного моделювання неоднорiдних пружних основ iз використанням меншої кiлькостi скiнченних елементiв. 5. Розроблений узагальнений метод релаксацiї може бути застосований до розв’язання низки нелiнiйних задач зi зворотними зв’язками при великiй чутливостi параметрiв, в тому числi суднобудiвних. У першому роздiлi виконано аналiз публiкацiй стосовно аварiй, пов’язаних з судновим валопроводом, методiв розрахунку компонентiв його НДС при згинаннi та умов його роботи. Аналiз аварiйностi суднових валопроводiв показав, що втомнi руйнування валiв, перегрiвання, плавлення, випiнг i втомне руйнування дейдвудних пiдшипникiв з бабiту, а також iнтенсивне зношення неметалевих дейдвудних пiдшипникiв, що змащуються водою, є достатньо частими причинами аварiй на суднах. Основою цих аварiй часом є неякiсне центрування валопроводу, занадто простi розрахунковi моделi валопроводу або виборi параметрiв центрування без врахування впливу функцiонування судна в умовах хвилювання, оскiльки зазвичай розглядається лише робота валопроводу при номiнальнiй потужностi головного двигуна та експлуатацiї судна на тихiй водi. Виконаний аналiз лiтератури дозволив визначити актуальний напрям дисертацiйного дослiдження. Другий роздiл дисертацiї присвячений опису основних методiв, що використано та розроблено у дисертацiї. Розроблено матрицю жорсткостi скiнченного елементу пружної основи з параболiчним законом змiни коефiцiєнта жорсткостi за довжиною, яка бiльш точно моделює деформування пiдшипникiв судового валопроводу та дозволяє зменшити необхiдну кiлькiсть скiнчених елементiв для одного пiдшипника. Запропоновано узагальнений метод релаксацiї, що забезпечує надiйну збiжнiсть методу послiдовних наближень при розв’язаннi нелiнiйних задач визначення компонентiв НДС при згинаннi валопроводу зi зворотними зв’язками. Метод релаксацiї дозволяє в залежностi вiд особливостей математичної моделi пiдбирати його параметри для забезпечення найбiльш надiйної збiжностi розв’язкiв при мiнiмально можливому числi iтерацiй. Третiй роздiл дисертацiї присвячено опису розроблених математичних моделей для розрахунку компонентiв НДС при згинаннi валопроводу як багатопрогонної непризматичної балки в статичних умовах та з урахуванням еласто-гiдродинамiчного змащення пiдшипникiв пiд час його обертання. Розроблено метод розрахунку компонентiв НДС при статичному згинаннi валопроводу одночасно у вертикальнiй та горизонтальнiй площинах, пiдшипники якого представленi односторонньою неоднорiдною нелiнiйною змiщуваною пружною основою, який враховує довжину, зазор та деформацiю вкладишiв, а також лiнiйнi та кутовi змiщення пiдшипникiв в обох площинах. Для розв’язання нелiнiйної системи рiвнянь статичного згину валiв у роботi використано метод скiнченних елементiв та метод послiдовних наближень з релаксацiєю. Статичний згин валiв розраховується як суперпозицiя двох розв’язкiв: згин вiд жорсткого змiщення вузлових опор у межах пiдшипника на його поверхнi (пружна основа вiдсутня); згин на пружнiй основi вiд зовнiшнiх сил та реактивних навантажень вiд жорсткого змiщення пiдшипникiв (вузловi опори у межах пружної основи вiдсутнi). Розроблено модель еласто-гiдродинамiчного змащення дейдвудного пiдшипника. Поля тиску змащення визначається методом скiнченних елементiв, радiальнi перемiщення вкладишу визначаються за допомогою наближеного асимптотичного методу, а рiвновага мiж ними – методом послiдовних наближень з релаксацiєю. Розроблено метод розрахунку компонентiв НДС при згинаннi суднового валопроводу з урахуванням змащення у декiлькох або всiх його пiдшипниках. Для розв’язання нелiнiйної системи рiвнянь динамiчного згину валiв у серединi довжини кожного пiдшипника вводиться допомiжна вузлова опора, реакцiя якої мiнiмiзується методами оптимiзацiї, а саме, – рою часток та внутрiшньої точки. При кожному розрахунку цiльової функцiї, для пошуку рiвноваги мiж реактивними моментами плiвки змащення та розцентруванням валiв було застосовано метод послiдовних наближень з релаксацiєю гiдродинамiчних тискiв. Четвертий роздiл дисертацiї присвячено опису математичних моделей зовнiшнiх факторiв, що впливають на роботу валопроводу пiд час руху судна на хвилях. Описано основнi концепцiї розрахунку хитавицi судна на нерегулярному морському хвилюваннi у частотнiй та часовiй областi на основi гiдродинамiчної теорiї хитавицi та спектральної теорiї нерегулярного хвилювання. Описано метод визначення iнерцiйних навантажень механiчної природи на елементи валопроводу при повздовжнiй хитавицi на нерегулярних хвилях. Дослiджено вплив iнерцiйних навантажень на навантаження пiдшипникiв валопроводу на рiзних режимах хвилювання та в екстремальних умовах. Описано застосування теорiї несучої поверхнi до розрахунку гiдродинамiчних навантажень на гребний гвинт пiд час руху судна на тихiй водi та на хвилях. Дослiджено залежнiсть амплiтуд навантажень на гребний гвинт, спричинених регулярними хвилями та хитавицею, вiд висоти та довжини хвилi. Описано методологiю оцiнювання загальних деформацiй корпусу судна шляхом чисельного iнтегрування рiвнянь згину i зсуву непризматичної балки та мiсцевих деформацiй днищового перекриття методом скiнчених елементiв у стержневiй iдеалiзацiї вiд змiни посадки судна та хвильових навантажень. Наведено формули визначення лiнiйних та кутових змiщень пiдшипникiв, спричинених загальною та мiсцевою деформацiями корпусу судна. Проведено дослiдження величин амплiтуд стрiлок прогину корпусу судна та днищового перекриття, а також вiдповiдних змiщень пiдшипникiв на регулярних хвилях в залежностi вiд висоти та довжини хвилi. У п’ятому роздiлi дисертацiї описано загальну модель функцiонування валопроводу з урахуванням його взаємодiї з корпусом судна при його русi на тихiй водi та в умовах нерегулярного морського хвилювання, а також загальну методологiю визначення навантажень на судновий валопровiд пiд час стоянки, руху судна на тихiй водi або регулярному та нерегулярному хвилюваннi. За допомогою розробленої моделi функцiонування проведено тестовi розрахунки навантажень, що дiють на валопровiд контейнеровоза 4400 TEU довжиною 280 м. Проведено аналiз впливу окремих зовнiшнiх факторiв пiд час хитавицi на роботу валопроводу.Ursolov O. I. Determination of loads acting on the shafting of the ship during its movement on intensive irregular waves. – Manuscript qualification scientific work. Thesis for the degree of philisophy doctor in speciality 135 – shipbuilding. – Admiral Makarov National University of Shipbuilding, Nikolaev, 2020. In the case of shafting failure during operation, the vessel loses movement and controllability. It can lead to overturning in rough weather conditions. On the other hand, failures associated with the shafting lead to loss of shipowner profit or loss of ability to perform a combat mission, as well as to large additional repair costs. More accurate marine propulsion shafting operation models and calculation schemes of its stress-deformed states will allow to predict possible risks of future shafting operation and to specify its design dimensions when designing a vessel or alignment parameters on existing vessels. This problem becomes especially relevant due to the fact that the modes of shafting operation during ship motions on the waves are the least studied at present. Thus, the relevance of the thesis research is determined by: 1. The need to improve the marine propulsion shafting models for the alignment calculation on calm water and the operation during ship motions. 2. The need to develop a comprehensive calculation method for assessing the impact of the ship motions on the joint operation of the ship–shafting system. 3. The need to conduct comprehensive studies of the impact of the ship motions on the shafting operation in order to determine the load acting on the shafting. The purpose of the thesis is to develop a method for determining the loads acting on the shafting during the joint operation of the ship–shaft system during ship motions on intensive irregular waves. The scientific novelty of the obtained results are as follows. 1. For the first time, using the methods of ship theory, ship structural mechanics and hydrodynamic lubrication theory, a complex model of the ship–shafting system dynamics during ship motion on waves, which takes into account propeller hydrodynamic forces, ship motion inertial forces, forces caused by ship’s hull deformation on waves and elastohydrodynamic lubrication in propeller shaft bearings is developed. 2. With the help of the obtained ship–shafting system operation model, for the first time a complex method of calculation of static and dynamic loads acting on the shafting, which are to be taken into account at the design and alignment calculation stages. 3. Using the finite element method, the method of marine propulsion shafting static bending calculation was improved, the bearings being represented as a one – sided inhomogeneous nonlinear displaceable elastic foundation, that allowed to take into account the length, clearance, deformation and offsets of bearings. 4. Using finite element and optimization methods, the method of marine propulsion shafting bending calculating with elastohydrodynamic lubrication in all bearings was improved, that allowed clarifying the conditions of its operation. 5. The bearing elastic foundation modeling using the finite element method was further developed, by means of which the expressions for the Winkler elastic foundation beam finite element were obtained, which allowed to take into account the change of the stiffness coefficient along the bearing length. 6. On the basis of generalization and extension of expressions for relaxation, methods of successive approximations relaxation were further developed, which allowed ensuring reliable convergence of marine propulsion shafting nonlinear calculations. The theoretical significance of the study is to develop a comprehensive marine propulsion shafting mathematical model and a generalized method for determining the loads acting on it, both when the ship does not move and when it is moving on calm water and in conditions of intensive regular and irregular waves. The practical significance of the obtained results are as follows. 1. The developed marine propulsion shafting method bending calculation methods in static and dynamic conditions can be used for more accurate alignment calculations. 2. The developed model of shafting operation during ship moving on irregular waves can be used to estimate the shafting bending parameters in order to take into account undesirable phenomena that require changes in its design and technological parameters. 3. The obtained dependencies can be used to assess the impact of the ship motions on the loads acting on the shafting. 4. The developed elastic foundation finite element with a parabolic stiffness coefficient along element length can be applied to more accurate modeling of inhomo geneous elastic foundations using fewer finite elements. 5. The developed generalized relaxation method can be applied to the solution of a wide range of nonlinear problems with feedback having high parameter sensitivity, including shipbuilding problems. In the first chapter, the publications on accidents related to the marine propulsion shafting, methods of its bending calculations and its operating conditions are analyzed. The analysis of marine propulsion shafting failures has shown that shafts fatigue failure, wiping, crowning, scoring and pitting of white metal stern tube bearings, as well as intensive wear of non–metallic water–lubricated stern tube bearings are quite common causes of ship failures. The common root causes of these failures are poor shaft alignment, too simple shafting calculation models or ignoring ship operation in rough weather at the shaft alignment calculation stage, as usually only the shafting operation at main engine rated power and calm water ship operation is considered. The performed literature analysis allowed to determine the relevant direction of the thesis research. In the second chapter, the main methods used and developed in the dissertation are described. An elastic foundation stiffness matrix with a parabolic stiffness coefficient along element length has been developed, which more accurately models the deformation of marine propulsion shafting bearings and allows reducing the required finite elements number for one bearing. A generalized relaxation method is proposed, proving reliable successive approximations method convergence in solving shafting bending nonlinear problems with feedback. The relaxation method allows performing adjustments its parameters according to the mathematical model features, providing the most reliable convergence of solutions with the minimum possible number of iterations. In the third chapter, the developed marine propulsion shafting bending mathematical models as a multi–span non–prismatic beam in static conditions and taking into account bearings elastohydrodynamic lubrication during shafting rotation are described. A method for shafting static bending calculation in both vertical and horizontal planes is developed, the bearings being represented as a one – sided inhomogeneous nonlinear displaceable elastic foundation taking into account the length, clearance and deformation of bearing bushes, as well as linear and angular bearings offsets in both planes. The finite element method and the method of successive approximations with relaxation are used were used to solve the nonlinear system of shafting static bending equations. Static bending of the shafting is represented as a superposition of two solutions: bending from the rigid displacement of nodal supports on the bearing surface (elastic foundation is absent); bending on an elastic foundation from external forces and reactive loads from rigid bearings displacements (nodal supports within an elastic basis are absent). A stern tube bearing elastohydrodynamic lubrication model is developed. Lubrication pressure fields are determined by the finite element method, the bearing bush radial displacements are determined by the approximate asymptotic method and the equilibrium between them are searched by the successive approximations method with relaxation. The shafting bending calculation method taking into account lubrication in several or all bearings is developed. To solve the dynamic shafting bending nonlinear system of equations, auxiliary nodal support is introduced in the middle of each bearing length. The reactions of these supports are minimized by the optimization methods, namely the particle swarm and the interior point methods. In each objective function calculation, the successive approximations method with hydrodynamic pressure relaxation of was applied to find the balance between the lubrication film reactive moments and the journal misalignment. In the fourth chapter, the mathematical models of the external factors affecting shafting operation during ship movement on the waves are described. The basic concepts of calculating ship motions on irregular sea waves in frequency and time domains based on hydrodynamic seakeeping theory and irregular waves spectral theory are described. A method for determining the mechanical inertial loads on the shafting elements during longitudinal ship motions on irregular waves is described. The influence of inertial loads on the shafting bearing loads at different weather conditions and in extreme conditions has been studied. The application of the lifting surface theory to the propeller hydrodynamic loads calculation during ship movement on calm water and on waves is described. The dependence of the additional propeller loads amplitudes caused by regular waves and ship motions, depending on the height and length of the wave is investigated. The methodology for estimating hull girder deflection by numerical integrating the non-prismatic beam bending and shear equations and local beam–idealized bottom grillage deflection by the finite element method caused by changes in the ship loading condition and wave loads is described. The formulas for determining the linear and angular bearing offsets caused by girder and bottom deflections are presented. The amplitudes of the girder and bottom deflections, as well as the corresponding bearing offsets, on regular waves depending on the height and length of the wave are studied. In the fifth chapter, the general shafting operational model taking into account its interaction with the ship hull during its movement on calm water and regular or irregular waves are described. Also, the general methodology for determining loads on the marine propulsion shafting when the ship does not move and during ship movement on calm water or regular and irregular waves are p

Comparative assessment and parametric optimisation of large marine two-stroke engines with exhaust gas recirculation and alternative turbocharging systems

Although the exhaust gas recirculation (EGR) technology has been proven effective to decrease the marine engine's nitrogen oxides (NOx) emissions, it is associated with a considerable fuel consumption increase and challenges to the engine−turbocharger matching. This study aims to parametrically optimise the EGR and turbocharging system settings of a large marine two-stroke engine with the objective of obtaining the highest engine efficiency whilst ensuring compliance with the prevailing NOx emissions limits. Two typical configurations of the investigated engine (baseline and alternative) are modelled in the GT-SUITE software. Parametric simulations are performed with EGR rates up to 40% along with cylinder bypass rates up to 50%, and the simulation results are analysed to quantify the impact of the engine operation with EGR on the performance and NOx emissions parameters. For the baseline engine configuration, the EGR rate increase considerably deteriorates the brake specific fuel consumption (BSFC), which is attenuated by opening the cylinder bypass valve. The optimal combinations of the EGR and cylinder bypass rates for each operating point are identified for both configurations. Following the comparative assessment between the two engine configurations, recommendations for the engine operating modes are proposed, leading to BSFC improvement in the region of 0.7 to 2.9 g/kWh. This study provides insights for the operational settings optimisation of two-stroke engines equipped with EGR systems, contributing towards the reduction of the associated environmental carbon footprint

Comparative Assessment and Parametric Optimisation of Large Marine Two-Stroke Engines with Exhaust Gas Recirculation and Alternative Turbocharging Systems

Although the exhaust gas recirculation (EGR) technology has been proven effective to decrease the marine engine’s nitrogen oxides (NOx) emissions, it is associated with a considerable fuel consumption increase and challenges to the engine–turbocharger matching. This study aims to parametrically optimise the EGR and turbocharging system settings of a large marine two-stroke engine with the objective of obtaining the highest engine efficiency whilst ensuring compliance with the prevailing NOx emissions limits. Two typical configurations of the investigated engine (baseline and alternative) are modelled in the GT-SUITE software. Parametric simulations are performed with EGR rates up to 40% along with cylinder bypass rates up to 50%, and the simulation results are analysed to quantify the impact of the engine operation with EGR on the performance and NOx emissions parameters. For the baseline engine configuration, the EGR rate increase considerably deteriorates the brake specific fuel consumption (BSFC), which is attenuated by opening the cylinder bypass valve. The optimal combinations of the EGR and cylinder bypass rates for each operating point are identified for both configurations. Following the comparative assessment between the two engine configurations, recommendations for the engine operating modes are proposed, leading to BSFC improvement in the region of 0.7 to 2.9 g/kWh. This study provides insights for the operational settings optimisation of two-stroke engines equipped with EGR systems, contributing towards the reduction of the associated environmental carbon footprint

Assessing Sustainability in the Shipbuilding Supply Chain 4.0: A Systematic Review

The supply chain is currently taking on a very important role in organizations seeking to improve the competitiveness and profitability of the company. Its transversal character mainly places it in an unbeatable position to achieve this role. This article, through a study of each of the key enabling technologies of Industry 4.0, aims to obtain a general overview of the current state of the art in shipbuilding adapted to these technologies. To do so, a systematic review of what the scientific community says is carried out, dividing each of the technologies into different categories. In addition, the global vision of countries interested in each of the enabling technologies is also studied. Both studies present a general vision to the companies of the concerns of the scientific community, thus encouraging research on the subject that is focused on the sustainability of the shipbuilding supply chain

Electromechanics of an Ocean Current Turbine

The development of a numeric simulation for predicting the performance of an Ocean Current Energy Conversion System is presented in this thesis along with a control system development using a PID controller for the achievement of specified rotational velocity set-points. In the beginning, this numeric model is implemented in MATLAB/Simulink® and it is used to predict the performance of a three phase squirrel single-cage type induction motor/generator in two different cases. The first case is a small 3 meter rotor diameter, 20 kW ocean current turbine with fixed pitch blades, and the second case a 20 meter, 720 kW ocean current turbine with variable pitch blades. Furthermore, the second case is also used for the development of a Voltage Source Variable Frequency Drive for the induction motor/generator. Comparison among the Variable Frequency Drive and a simplified model is applied. Finally, the simulation is also used to estimate the average electric power generation from the 720 kW Ocean Current Energy Conversion System which consists of an induction generator and an ocean current turbine connected with a shaft which modeled as a mechanical vibration system

Electromechanics of an Ocean Current Turbine

The development of a numeric simulation for predicting the performance of an Ocean Current Energy Conversion System is presented in this thesis along with a control system development using a PID controller for the achievement of specified rotational velocity set-points. In the beginning, this numeric model is implemented in MATLAB/Simulink® and it is used to predict the performance of a three phase squirrel single-cage type induction motor/generator in two different cases. The first case is a small 3 meter rotor diameter, 20 kW ocean current turbine with fixed pitch blades, and the second case a 20 meter, 720 kW ocean current turbine with variable pitch blades. Furthermore, the second case is also used for the development of a Voltage Source Variable Frequency Drive for the induction motor/generator. Comparison among the Variable Frequency Drive and a simplified model is applied. Finally, the simulation is also used to estimate the average electric power generation from the 720 kW Ocean Current Energy Conversion System which consists of an induction generator and an ocean current turbine connected with a shaft which modeled as a mechanical vibration system

Reliability-based design of offshore structures for oil and gas applications

Offshore structures are complex in their structural and functional form and operate in a harsh and uncertain environment with complex interactions between ocean variables. Consequently, the ocean environment presents a high risk to these structures hence the need to develop an efficient and reliable design. Therefore, the need for a design that effectively: captures complex ocean parameter interactions, reduces the computational burden in structural response determination, quantifies the structure's ability to bounce back when faced with disruptive events, and minimizes cost under uncertainty at the desired safety levels of the asset is critical. A robust offshore structural design under uncertainty is essential for the safety of life, asset, and the environment during oil and gas exploration and production activities. This thesis presents improved methods for the effective reliability-based design of offshore structures. First, a framework is developed to capture the dependency of multivariate environmental ocean variables using vine copula and its impact on the reliability assessment of offshore structural systems. The model was tested using a cantilever beam and applied to an offshore jacket structure. The comparative results from the jacket structure and cantilever problem reveals that failure probability considering dependence between ocean variables is closer to the reference value than when variables are independent or modeled with a Gaussian copula. The outcome shows the importance of capturing nonlinearity and tail dependence between ocean variables in reliability evaluation. Secondly, the effectiveness of a hybrid metamodel, which is a combination of two commonly and independently used methods, Kriging and Polynomial Chaos Expansions (PCE), is investigated for offshore structural response determination and reliability studies. The hybrid metamodel herein, called (APCKKm-MCS) is constructed from an adaptive process with multiple enrichment of Experimental Design (ED). The hybrid approach was tested on simple non-linear functions, a truss bar, and an offshore deepwater Steel Catenary Riser (SCR). The study's outcome revealed that APCKKm-MCS produced a high predictive response capacity, reduced model evaluation, and shorter computing time during reliability evaluation than the single enrichment case (APCK-MCS) and the adaptive ordinary Kriging case (AK-MCS) considered. In addition, a novel framework is developed for the resilience quantification of offshore structures in terms of their time-varying reliability, adaptability, and maintainability. The developed framework was demonstrated using an internally corroded pipeline segment subject to disruptive events of leak, burst, and rupture. The framework captured the resilience index of the natural gas pipeline for its design life, and its sensitivity analysis revealed the influence of the pipe wall thickness and corrosion depth growth rate on the resilience of the pipeline. The framework provides a quantitative approach to determine the resilience of offshore structures and ascertain their critical influencing parameters for effective decision-making. Finally, a methodology for optimal structural design under uncertainty considering the dependency of environmental variables with the implementation of a hybrid metamodel in the inner loop of a nested optimization problem is presented and demonstrated on a steel column function and a segmented SCR. The study showed different decision outcomes for various vine tree configurations in the dependence modeling for the steel column function noting the importance of choosing the appropriate variable order in the vine tree for optimal design under uncertainty. Also, the research reveals the suitability of adaptive PCK for the inner loop reliability phase for a double-loop structural optimization due to its high predictive capacity and observed relatively low cross-validation error. The method shows the importance of effective dependence modeling of environmental ocean variables in structural cost minimization and selecting optimal structural design variables under uncertainty. From the research outcomes, considering multivariate dependence between ocean variables using vine copula and utilizing multiple enrichment hybrid metamodels in response evaluation for reliability and optimal design assessment of offshore structures could better predict their failure probability and enhance a safer structural design. In addition, the resilience quantification framework developed provides a vital decision-making tool for offshore structural systems' design and integrity management. The research into high dimensional dependence modeling of offshore structures using vine copula, comparative study of sampling strategies required for the hybrid (Kriging and PCE) metamodel construction, dependence-based structural resilience quantification, and multiobjective dependence-based structural optimization under uncertainty are among areas proposed for future investigation