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Arctic cities are at the forefront of climate change, experiencing distinctive obstacles in their endeavors to pursue green transitions and attain sustainability objectives. These cities are marked by high energy consumption, primarily driven by activities related to resource extraction and the demanding climate. Moreover, they rely heavily on natural resources for growth, have limited infrastructure, and experience significant external and internal remoteness. This article presents a comprehensive analysis of urban sustainability in Arctic cities, focusing on key themes, trends, and challenges. Through a systematic review of extant literature, this study examines current research on urban sustainability in the Arctic and identifies crucial gaps, delineating a path to sustainability. Using VOSviewer software, six thematic clusters were identified: climate change and environmental adaptation, SDGs and smart urban planning, sustainable development and urban governance, sustainable economic development, social sustainability, and green energy transition. These clusters provide valuable insights into the dominant themes and evolving discourse in Arctic sustainability research. The findings show that the literature focuses predominantly on Russian Arctic cities, signaling an imperative for a more inclusive strategy encompassing a broader spectrum of Arctic cities. Additionally, sustainability is inherently site-specific and necessitates a nuanced understanding that incorporates different stakeholders’ perspectives and considers particular regional traits to create a more effective and meaningful approach to measuring and achieving sustainability in Arctic cities. This article contributes to the ongoing discourse on sustainability in Arctic cities by advocating for a comprehensive framework that accommodates unique challenges and opportunities of Arctic urban environments.

Arctic cities are often perceived as exceptional and uniquely challenged by extreme conditions, leading to their treatment as special cases in urban planning and development. However, this perception overlooks the reality that Arctic cities share similar issues common to many small and medium-sized urban centers globally, such as mobility, climate adaptation, and aging populations. By recognizing Arctic cities as ordinary cities, we can better address their needs and foster effective solutions. This article reflects on the results of a fourth-year Master-level course in Sustainable Urban Development, where students researched urban sustainability aspects (e.g., mobility, green infrastructure, energy, public spaces) in northern regions of Finland, Sweden, and Norway. It analyzes pedagogical approaches, highlighting challenges in integrating sustainability perspectives into architecture and planning curricula. Findings hold relevance for educators seeking to address similar challenges in the Arctic or other ordinary cities worldwide, contributing to more resilient and sustainable urban development across diverse environments.

The ongoing climate crisis and turbulence on the world stage has highlighted the need for sustainability and resilience in the development and maintenance of urban areas regarding climate comfort and energy access. Local production of green energy increases both the sustainability and resilience of an area. Traditionally, photovoltaic (PV) panels are deployed wherever the amount of sunlight is highest but lowering costs for PV panels makes them cost-effective even in colder climates. Within the broader umbrella of positive energy districts, façade mounted building-integrated PV panels in urban areas additionally present unique opportunities and challenges, as factors such as wind, solar irradiance, or nearby obstructions can have either a positive or negative effect on the performance of the PV panels. In this article, we aimed to answer the question: What factors inform the optimization of vertical PV panels? To answer this, we developed a method for the optimization of placement of PV panels. By building upon readily available weather data, local panel conditions were examined, and field-driven aggregation algorithm used to guide panel placement. Performance of the resulting panel configurations were then compared to a baseline case. Results indicate that our developed method helped mitigate negative impacts of the aforementioned factors, and often improved performance over baseline.

This article—framed as a methodological contribution and at the intersection between the critical urban, urban political ecology and world-ecology disciplines—builds on Corboz’s metaphor of ‘territory as a palimpsest’ to explore the representation of the socio-economic and ecological processes underpinning uneven development under extractive capitalist urbanization. While the palimpsest approach has typically been used to map transformations of more traditional urban morphologies, this work focuses instead on remote extraction territories appropriated by the global economy and integral to planetary urbanization. The article suggests the central notion of ‘palimpsests of appropriation’ as a lens to map the extraction processes. It does so in its multi-scalar and temporal dimensions and on the basis of the three intertwined frames—i.e., the productive, distribution and mediation palimpsest—shortly exemplifying its use on the ground for the iron ore extraction territory in the Swedish-Norwegian Arctic. With this, the article contributes to the development of an expanded representational methodology and conception of territories of extraction—where social and natural production are brought together—illustrating how appropriation has been (re)shaping each of the frames throughout historical thresholds, but also how socio-natures are being (re)made in its image.

The linear pattern of production-consumption-disposal of cities around the world will continue to increase the emission of pollutants and stocks of waste, as well as to impact on the irreversible deterioration of non-renewable stocks of raw materials. A transition towards a circular pattern proposed by the concept of ‘Circular Cities’ is gaining momentum. As part of this urban transition, the emergent use of Nature-based Solutions (NBS) intends to shift public opinion and utilize technology to mitigate the urban environmental impact. In this paper, an analysis of the current research and practical investments for implementing NBS under the umbrella of Circular Cities is conducted. A combined appraisal of the latest literature and a survey of ongoing and completed National-European research and development projects provides an overview of the current enabling tools, methodologies, and initiatives for public engagement. It also identifies and describes the links between facilitators and barriers with respect to existing policies and regulations, public awareness and engagement, and scientific and technological instruments. The paper concludes introducing the most promising methods, physical and digital technologies that may lead the way to Sustainable Circular Cities. The results of this research provide useful insight for citizens, scientists, practitioners, investors, policy makers, and strategists to channel efforts on switching from a linear to a circular thinking for the future of cities.

This paper investigates the behavior of SiC MOSFETs body diode reverse recovery as a function of different operating conditions. The knowledge of their effects is crucial to properly designing and driving power converters based on SiC devices, in order to optimize the MOSFETs commutations aiming at improving efficiency. Indeed, reverse recovery is a part of the switching transient, but it has a significant role due to its impact on recovery energy and charge. The set of different operating conditions has been properly chosen to prevent or force the snappy recovery of the device under testing. The experimental results and specific software simulations have revealed phenomena unknown in the literature. More specifically, the analysis of the reverse recovery charge, Qrr, revealed two unexpected phenomena at high temperatures: it decreased with increasing gate voltage; the higher the device threshold, the higher the Qrr. TCAD-Silvaco (ATLAS v. 5.29.0.C) simulations have shown that this is due to a displacement current flowing in the drift region due to the output capacitance voltage variation during commutation. From the analysis of the snappy recovery, it has emerged that there is a minimum forward current slope, below which the reverse recovery cannot be snappy, even for a high current level. Once this current slope is reached, Qrr varies with the forward current only.

This work analyzes the impact of working conditions on the current collapse (CC) phenomenon for an automotive GaN device. For this purpose, some sensing circuits have been compared to find the most suitable for the considered GaN family. Simulations of the testing schematic have been performed, a prototype board has been created, and some measurements have been taken. Finally, the work has investigated the effect on the CC of the input voltage, current level, switching frequency, and duty cycle. The key outcome is that the temperature increment mitigates the CC phenomenon, which implies that the on-state resistance worsening (dynamic/static ratio), which is due to the CC, reduces with increasing temperature. Therefore, the typical increment of the dynamic on-resistance (RDSON) with increasing temperature is ascribable to the increment of the static one with temperature, while it is not at all an exacerbation of the current collapse phenomenon.

Electromagnetic compatibility issues must be considered from the early steps in the design of electronic devices. A specific topic is the near-field emission generated by the device due to the traces on a printed circuit board and the specific routing. The analysis of near-field emission is essential to detect potential electromagnetic interference with nearby devices. This problem is crucial in high power density applications. Therefore, especially in these applications, it is necessary to optimize the circuit and the layout to minimize the generated noise. The design and construction of systems able to scan volumes to determine the spatial distribution of electrical E and/or magnetic B fields in the near-field region of a device under test is a very complex process. The realization of equipment that explores a given surface at a given distance from the device is easier. The main purpose of this paper is to show how it is possible to build a cheap two-dimensional scanner, starting from simple hardware not explicitly designed for near-field scan operations. The presented firmware and software solution can map, with good accuracy, the spatial distribution of fields B and E on a fixed plan close to the board. Finally, the developed system has been used in a GaN-based bi-directional DC/DC Converter.

GaN high electron mobility transistors (HEMTs) represent an emerging and key enabling technology for obtaining highly efficient and compact power electronic systems. The use of circuit models of power devices is essential for the optimal design of power converters, but while they have been deeply investigated for power MOSFETs and IGBTs, GaN HEMT models are still in their early stages. This paper first discusses the main similarities and differences between conventional MOSFETs and GaN HEMTs in terms of the datasheet information that the device manufacturers use to obtain the behavioral models that they usually provide as Spice-like netlists. Then, it highlights the strengths and weaknesses of using the behavioral models of MOSFET for GaN HEMT. To achieve this aim, a study of the existing GaN HEMT models revealed the lack of a proper modeling strategy for the dynamic conduction resistance, which is the most critical aspect of HEMT modeling. The difficulty is due to the dependence of the dynamic conduction resistance on quantities related to the application, which is a behavior absent in power MOSFETs. Consequently, future research efforts on GaN HEMT modeling must face this issue.

The thermal management of power converters is not only crucial for their own optimal operation and reliability, but also for the overall system in which they are operating. Reliability is a very serious aspect because power electronics systems are being increasingly widely adopted in mission-critical applications in the e-mobility sector, in smart grids, and other applications where safety and operational continuity are essential. The current trend towards miniaturization of power conversion systems and, consequently, towards high power density solutions is speeding up the diffusion of Gallium Nitride (GaN) High Electron Mobility Transistor (HEMT). GaN HEMT-based high power density converters must be properly managed, making the estimation of the thermal characteristics of these devices essential. This paper proposes the use of some Thermo-Sensitive Electrical Parameters (TSEP) for a simple and effective thermal resistance evaluation. The primary advantages and limitations of these TSEPs have been critically analyzed. The analysis highlighted that the use of the gate-source voltage is the best approach. However, it requires direct access to the gate pin, which may not be available externally in some system-in-package solutions.

Gallium nitride high-electron-mobility transistor (GaN HEMT) is a key enabling technology for obtaining high-efficient and compact power electronic systems. At the design stage of a power converter, the proper modelling of the GaN HEMT is essential to benefit from their good features and to account for the limits of the current technology. Circuit models of power MOSFETs have been deeply investigated by academia and industry for a long time. These models are able to emulate the datasheet information, and they are usually provided by device manufacturers as netlists that can be simulated in any kind of SPICE-like software. This paper firstly highlights the similarities and differences between MOSFETs and GaN HEMTs at the datasheet level. According to this analysis, the features of MOSFET circuit models that can be adopted for GaN HEMT modelling are discussed. This task has been accomplished by overviewing the literature on MOSFETs circuit models as well as analysing manufacturers netlists, thus highlighting the models MOSFETs valid or adaptable to GaN HEMTs. The study has revealed show that some models can be adapted for the GaN HEMT devices to emulate static characteristics at room temperature while the MOSFET models of dynamic characteristics can be used for GaN HEMT devices. This study enables the devices modellers to speed up the GaN HEMT modelling thanks to the use of some well-established MOSFET models. In this perspective, some suggestions to develop accurate GaN HEMT models are also provided.

A technique to improve the performance of grid-connected induction motors by exploiting an auxiliary winding set is proposed in this paper. This auxiliary winding features the same distribution of the main winding, although with a reduced number of turns and it is fed by an inverter a fraction of the power in comparison with the rated size of the induction motor. As shown in the paper, through the auxiliary winding, it is possible to set the machine power factor, increasing the efficiency of the power conversion system and mitigating speed oscillations due to torque disturbances. A mitigation of the grid current peaks due to motor start-up is obtainable. First, the proposed technique is theoretically introduced, then a feasibility assessment is accomplished by simulations.

In a high-power factor quasi-resonant Flyback, an ideal zero current detection (ZCD) circuit and control circuitry enable the power switch turn-on in the exact instant a zero ringing current is reached after demagnetization. A nonzero current at the turn-on instant affects the input current shape and; consequently, affects its Total Harmonic Distortion (THD). This paper firstly deeply analyzes the effect on the distortion due to a nonideal ZCD circuit. After, some typical implementations of the ZCD circuit and their effect on the THD are analyzed, identifying their pros and cons. Finally, some experimental results are obtained to validate the analytical investigation.

In this paper, a procedure to simulate an electronic power converter for control design and optimization purposes is proposed. For the addressed application, the converter uses SiC-MOSFET technology in bidirectional battery chargers composed of two power stages. The first stage consists of a single-phase AC/DC power factor correction synchronous rectifier. The following stage is a DC/DC dual active bridge. The converter has been modulated using a phase-shift technique which is able to manage bidirectional power flows. The development of a model-based simulation approach is essential to simplify the different design phases. Moreover, it is also important for the final validation of the control algorithm. A suitable tool consisting of a system-level simulation environment has been adopted. The tool is based on a block diagram design method accomplished using the Simulink toolbox in MATLAB™.

Nowadays, LED lamps have become a widespread solution in different lighting systems due to their high brightness, efficiency, long lifespan, high reliability and environmental friendliness. The choice of a proper LED driver circuit plays an important role, especially in terms of power quality. In fact, the driver controls its own input current in addition to the LED output current, thus it must guarantee a high power factor. Among the various LED drivers available on the market, the quasi-resonant (QR) flyback topology shows interesting benefits. This paper aims at investigating and analyzing the different issues related to the input current distortion in a QR flyback LED driver. Several effects, such as the distortion caused by the ringing current, crossover distortion due to transformer leakage inductance and crossover distortion due to the input storage capacitor have been experimentally reported. These effects, not previously studied for a high power factor (Hi-PF) QR flyback, have been analyzed in depth. Finally, some practical design guidelines for a Hi-PF QR flyback driver for LED applications are provided.

Grounding systems are essential parts of substations and power generation stations. The evaluation of transferred potentials from an active grounding system to other passive ones or to any near conductors is an important aspect to be considered, because transferred potentials may cause serious and fatal events. Moreover, it is an intrinsic issue of the Smart Grid where the ground systems of the power and ICT systems could be close to each other. Therefore, the estimation of the transferred potential is necessary at grounding system design stage for people safety and electric components safeguard. Numerical methods are the best choice to perform a truthful estimation, especially when large and complex grounding systems have to be designed. However, this task is complicated by the “unbounded„ nature of the electromagnetic field and by the presence of components of extremely different size in the analysis domain. In this paper, an efficient hybrid finite element method is applied for the accurate and fast computation of transferred earth potentials from grounding systems. Moreover, the small dimensions of the components in the analysis domain are taken into account by the use of one-dimensional finite elements inserted in the tetrahedral mesh. It is worth mentioning the additional advantage of obtaining the electric potential on the earth surface without any post-processing operation.

Energy-saving lamps are equipped with converters enabling high energy efficiency at the cost of injecting very distorted currents on the mains. The problem is more complex in the emerging smart-lighting scenario where these lamps are also used to perform additional tasks. Harmonics mitigation at the lamp level is expensive; consequently, an optimal lighting system design aiming at reducing both costs and current distortion of the whole lighting system is necessary. A tool able to emulate the current drawn from the lamps is necessary for optimal design. Such a tool has also to consider the fluctuations of the voltage on the mains that usually occur throughout the day. In this perspective, a parametric PSpice circuit is proposed and the netlist is reported in this work. Moreover, the simple procedure to be adopted for computing the parameters is also described. The validation has confirmed the ability of the proposed circuit in emulating the current drawn from various CFLs and LED lamps under different supplying voltage.