A study on the statistical calibration of the Holtrop and Mennen approximate power prediction method for full hull form, low froude number vessels

The article herein presents a statistical calibration study of the approximate power method of Holtrop and Mennen focused on adapting the method to vessels characterized as “full” hull forms and low design and operating speeds and, thus, low Froude numbers. The fitting of the method is done by adjusting the constants, coefficients, and components of the method’s equations by a systematic variation process controlled by genetic algorithms. The database that the method is calibrated against is consisted by model test results from modern (built between 2010 and 2016) bulk carriers and tankers, the KVLCC2, and the method follows a multistage approach, calibrating first the model for the prediction of total resistance and applying the self-propulsion equations afterward. The uncertainty of the new improved method is assessed and modeled with a nonlinear regression equation to enable the use of the calibrated method in the early ship design and optimization process

A novel method for the holistic, simulation driven ship design optimization under uncertainty in the big data era

The changing fuel costs, tough and volatile market conditions, the constant societal pressure for a «green» environmental footprint combined with ever demanding international safety regulations setup a completely new framework for commercial ship design. Ballast Water Treatment Systems, the ambitious IMO agenda for de-carbonization of shipping by 2050, the Goal Based Standards and most importantly the revision of the IMO MARPOL Annex VI, constitute a framework with strict and often contradicting requirements. On the other hand, the global economic uncertainty, rapid fleet growth and unsteady demand of commodities create a volatile economic operating environment for shipping companies. Ship design needs to adapt to this new reality. Holistic approaches, with lifecycle considerations, aiming at robust designs are deemed necessary. Such a methodology is presented herein. It is built within the software CAESES and is consisted by a geometrical model core with several integrated modules that cover stability, strength, powering and propulsion, safety, economics, as well as an operation simulation module, enabling the user to simulate the response in variations of the geometrical, design variables of the vessel under uncertainty. The latter is captured in several levels including Economic, Environmental, Operational uncertainty as well as the inaccuracy of the methods themselves

Simulation-driven robust optimization of the design of zero emission vessels

The International Maritime Organization (IMO) Decarbonization Roadmap for curbing and eliminating Greenhouse Gas (GHG) emissions by 2030 and 2050, respectively, is a “herculean” task in its own respect. If it is now combined with fundamental changes in trade dynamics, volatile market conditions, tighter shipping financing platforms with sustainability-linked interest rates and international safety regulations setup, a completely new framework for commercial ship design characterized by strict and often contradicting requirements emerge In parallel, zero carbon fuels available (readily or in the future) require extensive technological modifications and technical leaps in the current arrangements ship propulsion plants (with little to no existing reference) characterized by elevated consumption figures due to low energy density leading to an overshoot in voyage expense costs and the Total Cost of Ownership (TCO), respectively. Considering such a tight design space, holistic approaches with lifecycle considerations aiming at robust designs are deemed necessary. Pursuant to this roadmap, the authors have developed a design methodology fully integrated within the CAE software CAESES™ that encompass all aspects of ship design (stability, strength, powering and propulsion, safety, economics) and has an inherent dynamic voyage simulation module, enabling the user to simulate the response in variations of the geometrical, design variables of the vessel under uncertainty. The methodology has been extended to model the design and propulsion plant of an Ammonia powered Large Bulk carrier and deployed in global ship design optimization studies and utility-based ranking and selection process

A novel methodology for robust, holistic, simulation-based ship design optimization

Error on title page – year of award is 2023.The herein presented thesis presents the author’s research work on the field of ship design that fulfils the requirements of the Doctor of Philosophy degree. The original scientific research is focused on the field of ship design optimization with the novelty of lifecycle simulation from the early ship design stage (basic/preliminary ship design) as well as the use of digital twin models generated based on big data acquired from a fleet of actual vessels. Three different of layers for uncertainty have been added (market uncertainty, environmental and vessel operation uncertainty, method and model error modelling), tightly coupled with a comprehensive voyage simulation framework for the vessel’s entire lifecycle (25 years). This robust holistic design approach (RHODA) has been deployed for formal and global ship design optimization studies and compared against deterministic runs showing a great potential for more effective design space exploration resulting into more robust dominant variants over different environments and market conditions. To showcase the applicability and potential of the herein proposed RHODA method and research work, the methodology has been also adapted to be applicable for zero emission vessels (NH3 powered bulk carriers) and a global ship design optimization case study has been performed for such vessels yielding many interesting design points for the future.The herein presented thesis presents the author’s research work on the field of ship design that fulfils the requirements of the Doctor of Philosophy degree. The original scientific research is focused on the field of ship design optimization with the novelty of lifecycle simulation from the early ship design stage (basic/preliminary ship design) as well as the use of digital twin models generated based on big data acquired from a fleet of actual vessels. Three different of layers for uncertainty have been added (market uncertainty, environmental and vessel operation uncertainty, method and model error modelling), tightly coupled with a comprehensive voyage simulation framework for the vessel’s entire lifecycle (25 years). This robust holistic design approach (RHODA) has been deployed for formal and global ship design optimization studies and compared against deterministic runs showing a great potential for more effective design space exploration resulting into more robust dominant variants over different environments and market conditions. To showcase the applicability and potential of the herein proposed RHODA method and research work, the methodology has been also adapted to be applicable for zero emission vessels (NH3 powered bulk carriers) and a global ship design optimization case study has been performed for such vessels yielding many interesting design points for the future

Ανάπτυξη μια Ολιστικής Μεθόδου Βελτιστοποίησης τηε Σχεδίασης και Λειτουργίας Δεξαμενοπλοίων και Εφαρμογές της.

264 s.Η παρούσα εργασία αποτελεί την Διπλωματική Εργασία του γράφοντος, Λάμπρου Γ. Νικολόπουλου, στα πλαίσια ολοκλήρωσης των προπτυχιακών σπουδών του στο Εθνικό Μετσόβιο Πολυτεχνείο για την απόκτηση του Διπλώματος Ναυπηγού Μηχανολόγου Μηχανικού. Ο τίτλος της εργασίας στα ελληνικά μπορεί να μεταφραστεί ως «Ανάπτυξη μιας Ολιστικής Μεθόδου Βελτιστοποίησης Σχεδίασης και Λειτουργίας Δεξαμενοπλοίων και Εφαρμογές της», έχοντας ως επιβλέποντα τον Καθηγητή Απόστολο Παπανικολάου, Διευθυντή του Εργαστηρίου Μελέτης Πλοίου, της Σχολής Ναυπηγών Μηχανολόγων Μηχανικών του ΕΜΠ. Το αντικείμενο της Διπλωματικής είναι η ανάπτυξη μιας ολιστικής μεθόδου, με αρχές προσομοίωσης, πάνω στην οποία γίνεται συστηματική διερεύνηση και κατόπιν βελτιστοποίηση της σχεδίασης και λειτουργίας δεξαμενοπλοίων. Τα κριτήρια της βελτιστοποίησης μπορούν να συνοψισθούν στην ελαχιστοποίηση του ρίσκου και την μεγιστοποίηση της αποδοτικότητας και οικονομικής επίδοσης του πλοίου, έχοντας ως παραμέτρους τόσο τις κύριες διαστάσεις όσο και παραμέτρους των δεξαμενών φορτίου αλλά και τοπικές γεωμετρικές παραμέτρους. Η μεθοδολογία αναπτύχθηκε στο πρόγραμμα παραμετρικής σχεδίασης και προσομοίωσης πλοίων Friendship Framework στα πλαίσια της συνεργασίας της εταιρίας με το Εργαστήριο Μελέτης Πλοίου και τον Γερμανικό Νηογνώμονα για το ερευνητικό πρόγραμμα BEST++ (Better Economics with a Safer Tanker). Οι εφαρμογές της Μεθοδολογίας εντάσσονται στην προκαταρκτική μελέτη εφικτότητας και έως ένα βαθμό στον πιο λεπτομερή σχεδιασμό και είναι για δύο τύπου δεξαμενοπλοίων. ¨Ένα διπλέλικο δεξαμενόπλοιο τύπου AFRAMAX, με διάταξη δεξαμενών 5Χ3 και καινοτόμο γάστρα καθώς και ένα συμβατικό μονέλικο δεξαμενόπλοιο πολύ μεγάλου μεγέθους (VLCC).Over the last decade the regulatory framework in shipping has put big pressure on ship designers, owners and operators for an improvement of the safety onboard and a drastic reduction of the environmental footprint of shipping. This new status of the regulatory constraints in combination with harsh economic conditions, charter rates volatility, high uncertainty and rising fuel and insurance costs challenge the future ship designs to change. This Thesis presents a holistic methodology that was developed for the systematic variation and subsequent optimization of innovative tanker designs using principles of Risk Based Design realized by simulation driven design in the Friendship Framework. In the primary case study, the design concept is by definition a safer tanker in the AFRAMAX class, having two longitudinal bulkheads and twin screw/engine/skeg arrangement. A systematic and multi-staged optimization took place producing up to 6000 variants (with a total of 20000 working variants) having as an objective the reduction of the Required Freight Rate (indicative of transportation costs and including building, operational and crewing costs), the Accidental Oil Outflow Index (as defined by MARPOL Reg.23) and the Energy Efficiency Design Index (as adopted by IMO MEPC 62). The results show a significant improvement in both three objectives, with the dominant variants being more competitive and efficient than existing conventional designs. A post analysis is made examining the use of LNG as a fuel and new and innovative propulsion systems. In addition to the AFRAMAX case study, an applicability study has been made for the VLCC segment were the current results show a great potential for additional optimization. The sensitivities of both cases have been recorded and assessed.Lampros G. Nikolopoulo

Two- and Three-Photon Partial Photoionization Cross Sections of Li+, Ne8+ and Ar16+ under XUV Radiation

In this work, we present the photon energy dependence of the two- and three-photon cross sections of the two-electron Li+, Ne8+ and Ar16+ ions, following photoionization from their ground state. The expressions for the cross sections are based on the lowest-order (non-vanishing) perturbation theory for the electric field, while the calculations are made with the use of an ab initio configuration interaction method. The ionization cross section is dominated by pronounced single photon resonances in addition to peaks associated with doubly excited resonances. In the case of two-photon ionization, and in the non-resonant part of the cross section, we find that the 1D ionization channel overwhelms the 1S one. We also observe that, as one moves from the lowest atomic number ion, namely Li+, to the highest atomic number ion, namely Ar16+, the cross sections generally decrease

IoT Wearable Sensors and Devices in Elderly Care: A Literature Review

The increasing ageing global population is causing an upsurge in ailments related to old age, primarily dementia and Alzheimer’s disease, frailty, Parkinson’s, and cardiovascular disease, but also a general need for general eldercare as well as active and healthy ageing. In turn, there is a need for constant monitoring and assistance, intervention, and support, causing a considerable financial and human burden on individuals and their caregivers. Interconnected sensing technology, such as IoT wearables and devices, present a promising solution for objective, reliable, and remote monitoring, assessment, and support through ambient assisted living. This paper presents a review of such solutions including both earlier review studies and individual case studies, rapidly evolving in the last decade. In doing so, it examines and categorizes them according to common aspects of interest such as health focus, from specific ailments to general eldercare; IoT technologies, from wearables to smart home sensors; aims, from assessment to fall detection and indoor positioning to intervention; and experimental evaluation participants duration and outcome measures, from acceptability to accuracy. Statistics drawn from this categorization aim to outline the current state-of-the-art, as well as trends and effective practices for the future of effective, accessible, and acceptable eldercare with technology