126 research outputs found
An initial hierarchical systems structure for systemic hazard analysis of autonomous ships
No full text| openaire: EC/H2020/730888/EU//RESETSafety assurance of autonomous ships is one of the major long-term challenges faced by the maritime world. Applying systemic hazard analysis methods at this early stage will guide the design and operation of safe autonomous ships. This paper proposes an initial hierarchical ship systems structure that could be the basis for a systemic hazard analysis of autonomous ship systems and operations. The approach is based on the systems theory and the principle of hierarchy and has been developed via the combination of models used in past research projects and requirements of the STCW convention. For enabling the operation of autonomous ships, the ship crew functions are either replaced by ship technical systems or assigned to the Shore-Based Control Centre (SCC).Peer reviewe
Managing risks in maritime remote pilotage using the basis of the Formal Safety Assessment
No full textMaritime pilotage is conducted in congested areas, where the risk of collision and grounding accidents is high. Hence, the pilotage operation is safety critical and has been established as a mandatory service in many countries. However, with Remote Pilotage (RP) and related technological transformation, there is a need to adapt risk management methods to address emerging risks. This thesis aims to develop a framework to manage risks in RP by identifying gaps in the Formal Safety Assessment (FSA) framework and proposes novel solutions to fulfill them.
The thesis investigates Model-Based Systems Engineering (MBSE) for creating unambiguous system description models for the risk management process. Furthermore, this thesis addresses the selection challenge in MBSE by proposing a framework that assists system developers in choosing suitable MBSE language. Building upon the model, the thesis combines, System-Theoretic Process Analysis (STPA) and Bayesian Network (BN) for hazard identification and risk analysis. To reduce the limitations of other STPA-BN studies, the thesis explores the application of complexity reduction techniques such as the Parent Divorcing Technique, Noisy-OR gates, and the sub-models. Moreover, the thesis extends the STPA-BN method with a cost-benefit analysis using Influence Diagrams (IDs) for selecting a cost-effective Risk Control Option (RCO). Lastly, the thesis provides a methodology for the automatic generation of a BN risk model using an incident database and programming language, which facilitates real-time risk monitoring.
The proposed frameworks and solutions are then applied to RP for managing risks in early design phases. System description models, developed with selected MBSE language, are used together with STPA to identify the RP risk events such as losses, accidents, hazards, and causal factors. For each of these risk events, the occurrence probability is determined using a BN model. The model shows that the losses with high occurrence probability are loss of customer satisfaction, damage to the ship, injury to people, and damage to the environment. Furthermore, the model shows that collision and contact accidents have a higher occurrence probability than grounding during RP in Finnish fairways. For controlling these risk events in RP, an ID is developed and numerous RCOs are evaluated based on cost-benefit analysis. As a result, a cost-effective RCO for RP is proposed in the thesis. Finally, an automatic generation of BN risk models using a pilotage incident database and Python is demonstrated. The developed tool generates and updates the BN model providing the occurrence probability of risk events for real-time risk monitoring.
The results of this thesis demonstrate the applicability and effectiveness of the proposed framework. Furthermore, this thesis provides an essential foundation for managing risks in RP and facilitates its development. Last but not least, the thesis provides tools and methods supporting stakeholders in making risk-based decisions involving advanced systems
Assessment of the Required Subdivision Index for autonomous ships based on equivalent safety
No full textIn recent years, a significant amount of research has been conducted on autonomous ships. Since it is assumed that these ships will sail with a significantly reduced crew or even without people on board, the design of the ship needs reconsideration. The absence of people on board and the associated safety measures could result in a more efficient design. However, to achieve the required design freedom, the existing regulatory framework will have to be amended. In this article, we will focus on potential changes in the Convention for Safety Of Life At Sea (SOLAS) and in particular on the Required Subdivision Index. The evaluation is performed by using the principle of equivalent safety, which will ensure that unmanned ships will be at least as safe as manned ships. The index gives a requirement for the allowed probability of sinking when a ship is damaged due to collision or contact. The safety level is related to the safety of ship, cargo, environment and crew. If the crew is no longer present, the consequences of an incident will be less severe, since the probability of casualties is no longer present. If the principle of equivalent safety is applied, a lower subdivision index can be accepted for unmanned autonomous vessels. In this article, the level of risk that a manned ship is subjected to will be derived by means of a risk analysis. In this risk analysis all logical consequences of a collision will be taken into account, covering both the probability of losing the entire ship and the consequences of the cases where the ship will not sink. Thereafter, the Required Subdivision Index for unmanned ships, which ensures an equivalent safety level to an equivalent manned ship, is established. The sensitivity of the result to changes in the data is discussed as well.Ship Design, Production and Operation
Application of GNSS Precise Point Positioning to Low-Cost Hardware for cm-level Positioning
No full textPrecise Point Positioning (PPP) offers high-precision GNSS positioning solutions. The advent of low-cost hardware provides an affordable alternative to costly geodetic-grade hardware, broadening the accessibility of high-precision positioning across many applications. However, this hardware produces measurements with higher noise levels, reduced multipath suppression, and lower carrier-to-noise density ratios (C/N0), restricting its ability to achieve cm-level accuracy. This study addresses these limitations by developing a novel C/N0-based empirical observation weighting model to accompany the signal characteristics of low-cost hardware. This model enhances positioning accuracy by emphasizing high-quality signals above a nominal C/N0 threshold and down-weighting observations below it. The proposed model reduces float to carrier-phase integer ambiguity resolution (fixed) convergence time by 71% for 5 cm and 38% for 2.5 cm horizontal error thresholds for the static dataset tested, demonstrating the potential of low-cost GNSS devices as viable, high-precision positioning solutions
Review and comparison of the modeling approaches and risk analysis methods for complex ship system.
No full textMarine industry is leaning towards autonomous vessels with companies such as Rolls-Royce and Kongsberg leading the development. However, this rapid technological change invites greater risks and responsibilities for marine professionals. Ship systems are getting more complex with time as the interactions between components are increasing and software are getting embedded. As a result, the nature of risks in modern systems can be different than in the traditional systems, where the risks were mostly limited to human errors and component failures. However, for identifying risks in modern complex systems, it is first important to understand the structural composition of the system, and the component’s behavior, functions and interactions. Although, modern systems are quite different than traditional systems, traditional system-safety engineering techniques developed are still widely used.
This thesis aims to review a modern modeling approach known as Systems Modeling Language (SysML) and a risk analysis method known as Systems-Theoretical Process Analysis (STPA); and compare them against widely used traditional methods known as the Tree structure method and Fault Tree Analysis (FTA). SysML, developed in 2006, is a graphical modeling language which presents structural composition, component functions, behavior, constraints and requirements of a system. SysML aims to support the analysis, specification, design, verification and validation of complex systems. STPA, developed in 2011, is a risk analysis method which aims to identify and mitigate risks in a complex system. Unlike traditional methods such as Fault Tree analysis (FTA), STPA focuses on risks due to the unsafe control actions and component interactions. Furthermore, STPA can be also used during the early phases of the system development process to generate safety constraints and requirements for a safer design of the system.
This thesis also includes a workshop with Rolls-Royce where FTA, STPA, SysML and the Tree structure method were applied to a sample complex ship system. The results and feedback received from the workshop are presented and analyzed.
The results suggest that the modern methods such as SysML and STPA are more suitable than traditional methods for modeling and identifying risks in a complex ship system if the results of the method’s implementation are considered. SysML presents several aspects of systems in a model which are missing in the Tree structure method, such as the requirements of a system, and behavior and interaction of components. Furthermore, it also provides a model that can be used as a tool for conducting an analysis of a system. Similarly, STPA succeeds on identifying higher number of risks related to component interactions and human errors in comparison to FTA, as STPA analyzes all possible control actions in a system, whereas FTA only analyzes the risks that are known to the analysts. However, some drawbacks of SysML and STPA have also been identified. Although the methods are suitable for complex ship systems, the methods have higher degree of complexity and require more time for an analysis in comparison to traditional methods. Furthermore, some solutions to improve the identified drawbacks of SysML and STPA are proposed in this thesis. Finally, some viable future research topics to improve the research results are presented
Proceedings of the International Seminar on Safety and Security of Autonomous Vessels (ISSAV) and European STAMP Workshop and Conference (ESWC) 2019
No full textAalto University hosted the 2nd edition of the International Seminar on Safety and Security of Autonomous Vessels (ISSAV) together with the 7th edition of the European STAMP Workshop and Conference (ESWC). ISSAV promotes all aspects of maritime safety and security in the context of autonomous vessels. The seminar focuses on exchanging knowledge about key safety and security challenges and opportunities in the context of autonomous vessels and the autonomous maritime ecosystem. The ESWC focuses on applications and studies related to the Systems-Theoretic Accident Model and Processes (STAMP) which is a relatively new systems-thinking approach to engineering safer systems.
The 2nd edition of the International Seminar on Safety and Security of Autonomous Vessels (ISSAV) and the 7th edition of the European STAMP Workshop and Conference (ESWC) took place 17-20 September 2019 in Helsinki, Finland.
Scope – ISSAV
Autonomous vessels have become a topic of high interest for the maritime transport industry. Recent progress in the development of technologies enabling autonomous systems has fostered the idea that autonomous vessels will soon be a reality. However, before the first autonomous vessel can be released into her actual context of operation, it is necessary to ensure that it is safe and secure. The aim of ISSAV is to promote all aspects of maritime safety and security in the context of autonomous vessels. The seminar focuses on exchanging knowledge about key safety and security challenges and opportunities in the context of autonomous vessels and the autonomous maritime ecosystem. The seminar has a special emphasis on:
The challenges in managing safety and security in the operation of autonomous vessels and the entire ecosystem of an autonomous maritime system
Innovative approaches for managing the safety of autonomous vessels, supporting the design, operations and managerial strategies for ensuring the safety in the functioning of the autonomous maritime system.
Digitalization as technological enabler for efficient safety and security assurance in the context of autonomous shipping
Discussion and research on how to standardize safety approaches for autonomous vessels.
The development of intelligent security strategies for establishing resilient and robust systems for autonomous vessels
Safety and security integration in the operative context of autonomous maritime systems
Safety aspects of autonomous shipping in extreme environments
Scope – ESWC
Traditional system safety approaches are being challenged by the introduction of new technology and the increasing complexity of the systems we design, manufacture and operate. STAMP and its associated tools deal with the complexity of systems and provide systematic ways to analyze and assess existing and conceptual systems proactively or detect and illustrate deficiencies revealed through investigations. ESWC brings together researchers and practitioners who apply, or want to get familiar with, STAMP that is widely used in different sectors such as space, aviation, healthcare, defense, nuclear, railways, infrastructure and automotive.
The conference covers the following topics:
Experiences using STPA, STPA-Sec, and CAST
Introducing STAMP, STPA, and CAST into large organizations
Safety-guided and Security-guided design using STPA and STPA-Sec
Using STPA to make decisions
Accident/loss analyse
Towards maritime traffic coordination in the era of intelligent ships: a systems theoretic study
No full textCoordination of maritime traffic has developed over centuries with the main purpose of decreasing collisions and groundings of vessels. It has evolved from rudimentary measures, such as lighthouses, into an increasingly digitized setting with technologies like satellite positioning services and traffic coordination systems, such as the Automatic Identification System (AIS). In the future, increasingly intelligent shipping practices are expected to set further requirements not only for the ships themselves, but also for the coordination systems in maritime transport. Advanced and reliable coordination is especially seen as a key enabler for remote operated and autonomous ships.The introduction of autonomous and unmanned smart ships is likely to be gradual, and coordination techniques of different technology levels are likely to co-exist in the maritime setting for an unforeseen period: there will be highly connected intelligent vessels and those applying very basic means of perception and communication. Based on the Systems-Theoretic Accident Model and Processes (STAMP) approach, as well as the related STPA hazard analysis methodology, this paper presents a control structure of maritime traffic coordination as it is now, and provides an overview of STPA hazard analysis performed on the system. It also discusses changes foreseen in the structure due to changing means of coordination in the future, providing basis for better understanding of the risks and opportunities. Additionally, the paper provides insights on applicability of STPA on a new application area of maritime traffic coordination
Proceedings of the International Seminar on Safety and Security of Autonomous Vessels (ISSAV) and European STAMP Workshop and Conference (ESWC) 2019
No full textAalto University hosted the 2nd edition of the International Seminar on Safety and Security of Autonomous Vessels (ISSAV) together with the 7th edition of the European STAMP Workshop and Conference (ESWC). ISSAV promotes all aspects of maritime safety and security in the context of autonomous vessels. The seminar focuses on exchanging knowledge about key safety and security challenges and opportunities in the context of autonomous vessels and the autonomous maritime ecosystem. The ESWC focuses on applications and studies related to the Systems-Theoretic Accident Model and Processes (STAMP) which is a relatively new systems-thinking approach to engineering safer systems.
The 2nd edition of the International Seminar on Safety and Security of Autonomous Vessels (ISSAV) and the 7th edition of the European STAMP Workshop and Conference (ESWC) took place 17-20 September 2019 in Helsinki, Finland.
Scope – ISSAV
Autonomous vessels have become a topic of high interest for the maritime transport industry. Recent progress in the development of technologies enabling autonomous systems has fostered the idea that autonomous vessels will soon be a reality. However, before the first autonomous vessel can be released into her actual context of operation, it is necessary to ensure that it is safe and secure. The aim of ISSAV is to promote all aspects of maritime safety and security in the context of autonomous vessels. The seminar focuses on exchanging knowledge about key safety and security challenges and opportunities in the context of autonomous vessels and the autonomous maritime ecosystem. The seminar has a special emphasis on:
The challenges in managing safety and security in the operation of autonomous vessels and the entire ecosystem of an autonomous maritime system
Innovative approaches for managing the safety of autonomous vessels, supporting the design, operations and managerial strategies for ensuring the safety in the functioning of the autonomous maritime system.
Digitalization as technological enabler for efficient safety and security assurance in the context of autonomous shipping
Discussion and research on how to standardize safety approaches for autonomous vessels.
The development of intelligent security strategies for establishing resilient and robust systems for autonomous vessels
Safety and security integration in the operative context of autonomous maritime systems
Safety aspects of autonomous shipping in extreme environments
Scope – ESWC
Traditional system safety approaches are being challenged by the introduction of new technology and the increasing complexity of the systems we design, manufacture and operate. STAMP and its associated tools deal with the complexity of systems and provide systematic ways to analyze and assess existing and conceptual systems proactively or detect and illustrate deficiencies revealed through investigations. ESWC brings together researchers and practitioners who apply, or want to get familiar with, STAMP that is widely used in different sectors such as space, aviation, healthcare, defense, nuclear, railways, infrastructure and automotive.
The conference covers the following topics:
Experiences using STPA, STPA-Sec, and CAST
Introducing STAMP, STPA, and CAST into large organizations
Safety-guided and Security-guided design using STPA and STPA-Sec
Using STPA to make decisions
Accident/loss analyse
Systeemiteoreettinen prosessianalyysi alusten ja satamarakenteiden kansainvälisen turvasäännöstön puitteissa
No full textMaritime security includes preventive measures intended to protect port facilities and ships against threats of intentional unlawful acts. These measures are essential part of contemporary activities of shipping, ports, administrations, as well as a great number of seafarers and other maritime professionals. Contemporary legal regime governing maritime security is the Safety of Life at Sea (SOLAS) Convention Chapter XI-2 on Special Measures to Enhance Maritime Security and the International Ship and Port facility Security (ISPS) Code.
This thesis demonstrates how to enhance understanding about maritime security governance by using the System-Theoretic Process Analysis for Security (STPA-SEC) method. Ultimately, this thesis provides a novel application of the method in the framework of the ISPS Code and in the Finnish context. This study defines losses, hazards and constraints in the maritime security context and submits a model for hierarchical ISPS Code based control structure, which includes the interactions of controllers, processes, and controlled processes. With a rigorous application of the STPA-SEC, this study identifies unsecure control actions and loss scenarios. The enhancement and the verification of the model are done through a workshop and interviews with maritime security experts.
The research results suggest that the STPA-SEC is a suitable and comprehensive security hazard analysis method in order to systematically model the ISPS requirements, covering holistically both ship and port facility aspects. STPA-SEC is found to be an effective method in order to identify loss scenarios, with results that have practical significance for ship and port owners as well as respective security actors to adapt and maintain security functions align with the maritime security requirements.Merenkulun turvatoimiin kuuluu ennaltaehkäiseviä toimenpiteitä, joiden tarkoituksena on suojella satamarakenteita ja aluksia tahallisten laittomien tekojen uhalta. Nämä toimenpiteet ovat olennainen osa merenkulun, satamien, hallintojen sekä lukuisten merenkulkijoiden ja muiden merenkulkualan ammattilaisten nykyaikaista toimintaa. Ajantasainen merenkulun turvatoimia sääntelevä oikeudellinen kehys perustuu ihmishengen turvallisuudesta merellä koskevan SOLAS-yleissopimuksen XI-2 lukuun ja kansainväliseen alusten ja satamarakenteiden turvasäännöstöön (ISPS).
Opinnäytetyö osoittaa, miten merenkulun turvatoimien hallintaa voidaan ymmärtää paremmin käyttämällä systeemiteoreettista prosessianalyysimenetelmää (STPA-SEC). Viime kädessä tämä opinnäytetyö tarjoaa kyseisen menetelmän uudenlaista soveltamista ISPS-säännöstön kehyksessä ja suomalaisessa kontekstissa. Tässä tutkimuksessa määritellään merenkulun turvatoimiin liittyvät menetykset, uhat ja systeemirajoitteet sekä esitetään ISPS-koodiin pohjautuva hierarkkisen kontrollirakenteen malli, joka sisältää kontrollereiden, prosessien ja hallittujen prosessien vuorovaikutukset. Menetelmää soveltamalla tässä tutkimuksessa tunnistetaan epäturvallisia kontrollitoimia ja menetyksiin johtavia skenaarioita. Luodun mallin kehittäminen ja verifioiminen tapahtuu merenkulun turvallisuusasiantuntijoiden työpajan ja haastattelujen avulla.
Tutkimustulokset viittaavat siihen, että STPA-SEC on sopiva ja kattava analyysimenetelmä vaarojen arvioimiseksi ja sillä voidaan systemaattisesti mallintaa ISPS-koodin vaatimuksia kattaen kokonaisvaltaisesti sekä laiva- että satamarakennenäkökohdat. STPA-SEC -menetelmä todetaan tehokkaaksi keinoksi tunnistaa menetyksiin johtavia skenaarioita, joiden tuloksilla on käytännön merkitystä alusten ja satamien omistajille sekä muille vastaaville turvallisuustoimijoille, jotta ne voivat mukauttaa ja ylläpitää turvallisuusvaatimusten mukaisia turvatoimintoja
Micro-Erythrocyte Sedimentation Rate in Neonatal Sepsis of a Tertiary Hospital: A Descriptive Cross-sectional Study
No full textIntroduction: Neonatal sepsis is the most important cause of morbidity and mortality among low
birth weight and preterm babies in developing countries. The main objective of this study is to find
the level of micro-Erythrocyte sedimentation rate in neonatal sepsis.
Methods: This is a descriptive cross-sectional study conducted at the neonatal unit over six months
period (November 2019 to April 2020). All preterm, term and post-term babies with neonatal sepsis
delivered at Kathmandu Medical College Teaching Hospital were enrolled. Ethical clearance was
received from the Institutional Review Committee of Kathmandu Medical College (Ref: 181020191).
Convenient sampling method was applied and statistical analysis was done with Statistical package
for social sciences 19 version.
Results: Out of 75 babies, confirm sepsis is 13 (17.3%), probable sepsis is 40 (53.4%) and suspected
sepsis is 22 (29.2%). Micro-Erythrocyte sedimentation level is elevated (≥15mm in 1st hr) in 25 (33.3%)
babies with a mean micro-Erythrocyte sedimentation level 9.32±5.4 (2-18) mm in 1st hr. The elevated
micro- Erythrocyte sedimentation level was seen in relation to sepsis types and C-reactive protein.
Conclusions: The bedside micro-Erythrocyte sedimentation level aids in the diagnosis of neonatal
sepsis
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