Exploring the impact of different cost heuristics in the allocation of safety integrity levels

Contemporary safety standards prescribe processes in which system safety requirements, captured early and expressed in the form of Safety Integrity Levels (SILs), are iteratively allocated to architectural elements. Different SILs reflect different requirements stringencies and consequently different development costs. Therefore, the allocation of safety requirements is not a simple problem of applying an allocation "algebra" as treated by most standards; it is a complex optimisation problem, one of finding a strategy that minimises cost whilst meeting safety requirements. One difficulty is the lack of a commonly agreed heuristic for how costs increase between SILs. In this paper, we define this important problem; then we take the example of an automotive system and using an automated approach show that different cost heuristics lead to different optimal SIL allocations. Without automation it would have been impossible to explore the vast space of allocations and to discuss the subtleties involved in this problem

PM fractional machines adopting bonded magnets: effect of different magnetizations on the energetic performance

The adoption of Permanent Magnets in small brushless machines for automotive applications is becoming frequent. Some research on bonded magnets is being carried on to substitute the ferrites. In the paper the parallel and radial magnetizations are considered: the different process complexity levels are analyzed and the effects on the iron losses and the energetic performances are evaluated by means of a simulation analysis and its experimental validatio

Power Semiconductors for An Energy-Wise Society

This IEC White Paper establishes the critical role that power semiconductors play in transitioning to an energy wise society. It takes an in-depth look at expected trends and opportunities, as well as the challenges surrounding the power semiconductors industry. Among the significant challenges mentioned is the need for change in industry practices when transitioning from linear to circular economies and the shortage of skilled personnel required for power semiconductor development. The white paper also stresses the need for strategic actions at the policy-making level to address these concerns and calls for stronger government commitment, policies and funding to advance power semiconductor technologies and integration. It further highlights the pivotal role of standards in removing technical risks, increasing product quality and enabling faster market acceptance. Besides noting benefits of existing standards in accelerating market growth, the paper also identifies the current standardization gaps. The white paper emphasizes the importance of ensuring a robust supply chain for power semiconductors to prevent supply-chain disruptions like those seen during the COVID-19 pandemic, which can have widespread economic impacts.The white paper highlights the importance of inspiring young professionals to take an interest in power semiconductors and power electronics, highlighting the potential to make a positive impact on the world through these technologies.The white paper concludes with recommendations for policymakers, regulators, industry and other IEC stakeholders for collaborative structures and accelerating the development and adoption of standards

Stability Analysis and Control Design for Hybrid AC-DC More-Electric Aircraft Power Systems

This thesis studies the stability of a more-electric aircraft (MEA) power system with hybrid converters and loads, and proposes a control design method using state feedback. The MEA is aimed to replace the conventional nonelectric power in aircraft with electric power in order to reduce the size and weight of the aircraft power system. This thesis considers a model of the MEA power system consisting of the following components: converters with uncontrolled diodes and controlled rectifiers, ideal constant power loads (CPL), and non-ideal CPL driven by electromechanical actuators. The system has narrow stability range under the conventional two-loop PI control. To improve control performance, a full-state feedback control method is developed that can significantly increase the stability margin of the MEA power system

Electrical Machine Topologies: Hottest Topics in the Electrical Machine Research Community

In this article, the state of the art in electrical machine design is outlined underlining the problems and challenges to be solved by engineers. As highlighted in this article, even if electrical machine design is often considered a mature issue from the technical and technological point of view, every year, new progresses and steps forward are made. New and more sophisticated design tools can be used worldwide, and innovative manufacturing processes, new insulation materials, and higher performance magnetic materials are available on the market. In addition, the evolution of the hardware used in digital control and new powerful power electronic devices represents a constant stimulus to improve the performance of electrical machines and reintroduce electrical machine structures that were not adopted in the past due to technological and technical constraints. As shown in this article, electrical machine design is an evergreen topic, and its importance is rising more each year under the push of more energy-saving requirements and higher-efficiency systems for electromechanical conversion. A green world will not be possible without electrical machines

The state-of-the-art of dc power distribution systems/components for space applications

This report is a survey of the state of the art of high voltage dc systems and components. This information can be used for consideration of an alternative secondary distribution (120 Vdc) system for the Space Station. All HVdc components have been prototyped or developed for terrestrial, aircraft, and spacecraft applications, and are applicable for general space application with appropriate modification and qualification. HVdc systems offer a safe, reliable, low mass, high efficiency and low EMI alternative for Space Station secondary distribution

Plastic circular economy in the EU: Material Flow Analysis and Transition Analysis

Plastic is valued for its versatility, but concerns have been raised over the environmental impacts of plastic waste. A more in-depth investigation of the plastic system is still needed to understand current flows and factors to close the plastic cycle. This research applied a material flow analysis (MFA) and transition analysis (TA), using multilevel perspectives, to the plastic circular economy transition in the EU. The MFA covers over 400 categories of plastic-containing products with a detailed analysis of the final destination of waste. The TA identifies the interaction of barriers and drivers to use secondary plastics, with a focus on the regime level along the plastic value chain. The MFA results indicate the EU produced over 66  million tonnes (Mt) of plastic polymers/fibres and an estimated consumption for plastic products of 73 Mt in 2016. Plastic waste increases amounted to over 37 Mt, and a significant amount of plastic waste was not recovered back into plastics in the EU. The uncertainty analysis of MFA highlights important data quality issues that need to be addressed. To understand why using secondary plastics presents challenges, the TA mapped the factors across policies and standards, markets and business models, technology, and consumer preferences and behaviours that create a web of constraints and a web of drivers. TA results highlight that data-information-knowledge is the key gap as most of the aspects are cross-cutting. Different actors are involved in new business networks and play multiple roles in driving the co-evolutionary dynamic. The thesis concludes that significant data gaps need MFA-based knowledge to inform policies that address the barriers and the potential socio-technical changes that can reshape plastic flows. The cases playing out across the whole value chain and four different application areas provide insights that are potentially more widely applicable to the circular economy transition processes in Europe

Investigating Optimized Airplane Electrical Power Systems Using Advanced Energy Generation, Storage and Conversion Technologies

This work addresses the optimized integration of new types of electrical power system energy storage and energy generation devices into advanced electrical power systems for commercial airplanes. The objective of this research is to identify how new energy generation and storage system technologies, such as batteries, fuel cells and super capacitors, can be successfully integrated into an optimized and more efficient future airplane electrical power system architectures with success being measured from the standpoint of improvements in airplane, efficiency, reliability and maintainability. The baseline airplane electrical power system architecture that was chosen as a reference starting point for this study is a scaled model of Boeing's 787 "More Electrical Airplane" (MEA) due to its significantly increased electrification in comparison to all other commercial transport airplanes flying today. The 787 power system is unique in that it replaces nearly all of the pneumatically powered systems and some of the hydraulically powered systems with electrical power. This system architecture was incorporated on the 787 in order to provide significant advancements in airplane efficiency and to enable increased airplane performance and range along with decreased fuel burn and an associated decrease in emissions detrimental to the environment.The 787 MEA also incorporates a much more distributed electrical power system architecture and makes significantly increased use of power electronic conversion technology. Similarities can thus be drawn between the MEA and what is occurring with microgrids in the utility industry and electric and fuel cell powered automobiles in the transportation industry. Consequently technical information can be drawn from those industries technologies that potentially is useful in the research and development of an advanced MEA.Through the combination of the simulation and analysis this research shows that incorporation of these new energy generation and storage systems into a future MEA electrical power system along with changes in system conversion systems, electrical loads, and the overall electrical power system architecture would result in a significant increase in overall airplane efficiency along with other improvements for a future MEA