DERIVING SAFETY REQUIREMENT HIERARCHIES FOR FAMILIES OF MARITIME SYSTEMS

Ensuring the safety of advanced maritime vessels is a challenging task. While technological developments provide new options for their design and operation, the criteria for certification, such as class rules intended to ensure safety, may not be flexible enough to accommodate rapid changes. Innovation may enable more efficient, greener, and smarter systems but it may also introduce new hazards that are not addressed by current safety requirements. This paper proposes a method aimed at developing requirement hierarchies that are generic for a family of systems (such as a class of ships) and that can be adapted and specialised for a subset of the family or a particular system. Systems-theoretic process analysis (STPA) is used to develop safety requirements that are structured in a way that ensures that they can easily be kept up to date to accommodate new technological solutions and new alternatives for the design and operation of maritime vessels.

SARS-COV-2 Vaccination and Employment: the Legal Framework in the EU and Hungary

The paper explores whether and under what conditions, vaccination against SARS-CoV-2 may become a mandatory requirement for employees. It includes a discussion on EU action on SARS-CoV-2 vaccination and its relevance for national level policy with emphasis on the legal basis and instruments used by the Union to persuade national authorities into action to increase vaccination uptake. The analysis then moves to the national level by focusing on the case of Hungary. Following an overview of the legal and regulatory framework for SARS-CoV-2 vaccines deployment, the analysis zooms into the sphere of employment and explores whether and how the SARS-CoV-2 vaccination may be turned into a mandatory workplace safety requirement. The paper highlights the decision of the Hungarian government to introduce compulsory vaccination for employees in the healthcare sector, and concludes with a discussion of the relevant rules and their potential, broader implications.

Comparative Analysis Deferent Topologies for Photovoltaic Based Grid-Tied Transformerless Inverters

Transformerless inverters are widely used in grid-tied photovoltaic (PV) generation systems, due to the benefits of achieving high efficiency and low cost. Various transformer less inverter topologies have been proposed to meet the safety requirement of leakage currents. In this paper, a family of H6 transformer less inverter topologies with low leakage currents is proposed, and the intrinsic relationship between H5 topology, highly efficient and reliable inverter concept (HERIC) topology, and the proposed H6 topology has been discussed as well. One of the proposed H6 inverter topologies is taken as an example for detail analysis with operation modes and modulation strategy. The power losses and power device costs are compared among the H5, the HERIC, and the proposed H6 topologies. A universal prototype is built for these three topologies mentioned for evaluating their performances in terms of power efficiency and leakage currents characteristics. Experimental results show that the proposed H6 topology and the HERIC achieve similar performance in leakage currents, which is slightly worse than that of the H5 topology, but it features higher efficiency than that of H5 topology.

Review on Photovoltaic Based Grid-Tied System using H6 Transformer Less Full-Bridge Inverters

Transformer less inverters are widely used in grid-tied photovoltaic (PV) generation systems, due to the benefits of achieving high efficiency and low cost. Various transformer less inverter topologies have been proposed to meet the safety requirement of leakage currents, such as specified in the VDE-4105 standard. In this thesis, a family of H6 transformer less inverter topologies with low leakage currents is proposed, and the intrinsic relationship between H5 topology, highly efficient and reliable inverter concept (HERIC) topology, and the proposed H6 topology has been discussed as well. One of the proposed H6 inverter topologies is taken as an example for detail analysis with operation modes and modulation strategy. The power losses and power device costs are compared among the H5, the HERIC, and the proposed H6 topologies. A universal prototype is built for these three topologies mentioned for evaluating their performances in terms of power efficiency and leakage currents characteristics. Experimental results show that the proposed H6 topology and the HERIC achieve similar performance in leakage currents, which is slightly worse than that of the H5 topology, but it features higher efficiency than that of H5 topology.

Pembelajaran Kecelakaan Nuklir Fukushima bagi Indonesia

The Fukushima nuclear accident that occurred a decade ago has been considered a major accident. In this decade period, various important aspects of this accident were considered well-established for learning to improve nuclear safety infrastructure and prevent similar major accidents. The learning is very relevant for Indonesia, which is considered as an embarking country. Thus, this paper aims to assess the lessons that have been and can be learned by Indonesia from the nuclear accident. This study applies an analytical, descriptive and qualitative methodology using secondary data. In the first step, the important aspects of safety in the accident were identified applying the IAEA general safety requirement standards. The next step is the identification of relevant topics for each of these aspects in order to detail the lessons learned through an analysis of existing laws and regulations and international standards. This paper concludes that Indonesia has learned the lessons from the Fukushima nuclear accident in the aspects of international agreements, regulatory principles, and in accident prevention and mitigation. However, Indonesia still needs significant upgrading in the aspect’s leadership for safety and improvements in all these aspects. If a national decision has been made to build nuclear power plant, then these upgrading and improvements must be made to prevent a large-scale nuclear accident as happened at the Fukushima nuclear power plants.