47011 research outputs found
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Respecting nature’s limits in urban planning: values and principles for human–nature partnerships
Get PDFThe transgression of planetary boundaries demands that societal and ethical limits to Nature’s availability for human use, impact, and consumption are set, particularly in cities. However, so far, we lack an understanding of how sustainability-aligned values can define such limits and how limits can be operationalized in practice. The objectives of this perspective paper are therefore twofold. First, based on partnership ethics and the sociological concept of Uncontrollability, we identify broad values that feed into the concept of human-nature partnerships that respect limits to making Nature controllable. Second, we translate these broad values into four guiding principles that support urban planning to operationalize human-nature partnerships. Planning for urban human-nature partnerships thereby enables cities to become regenerative, healthy, convivial, and compassionate. Our concept of urban human-nature partnerships provides a heuristic for amplifying Nature’s voice and underscores the importance of relational capacities that enable urban planning to respond attentively
Diverse hydrogen chemistry with perspectives for energy storage
Get PDFThe chemistry of hydrogen and its interaction with matter is remarkably diverse with new discoveries and materials continuously being uncovered. New types of chemical bonding and interactions allow for the preparation of new compounds with unusual compositions and properties. For instance, neutral hydrogen molecules may spontaneously form penta-dihydrogen clusters, (H2)5, in nanoporous materials with extremely dense packing, similar to metallic hydrogen at high pressure. Hydrides with extreme hydrogen densities – ‘superhydrides’ – have yielded record critical temperatures under pressure and now guide routes toward low-pressure high-temperature hydride superconductors. A well-known weak interaction identified in biological matter, the hydrogen bond, has an inorganic analogue: the dihydrogen bond. These two interactions have very similar bond lengths and bond strengths that are known to produce flexible and relatively open structures, which often have interesting functionalities. Recently, the di-hydrogen bond has come into focus for development of fast divalent magnesium and calcium cationic conductors. In this review, we highlight key advances in the synthesis and characterisation of novel hydrogen-based materials and illustrate how the compositional and structural versatility of hydrides leads to new functionalities. Hydrides are highly relevant materials with a diversity of energy applications such as solid-state hydrogen storage, solid-state batteries and superconductors, as well as future global hydrogen transportation
Advanced feedforward control techniques: Comprehensive review and a real-time industrial application
No full textFeedforward control (FFC), often paired with feedback, is widely applied in industry to improve accuracy under transient conditions and reject disturbances. Despite this, academic attention has been limited, with few comprehensive reviews connecting algorithms to practical applications. This work bridges that gap by surveying classical and advanced FFC strategies, their advantages and drawbacks, and their implementation across diverse sectors. Classical FFC improves tracking and disturbance rejection through methods such as inverse modelling and input shaping, but faces challenges from instability, intensive tuning, and model inaccuracies. Hybrid techniques, including model predictive and active disturbance rejection control, broaden capability yet remain constrained by complexity and sensitivity to nonlinearities. Recent advances introduce look-ahead, adaptive, optimization-based, and data-driven methods. Preview and predictive designs enhance responsiveness but depend on accurate future estimation, while iterative and intelligent approaches reduce modelling requirements at the expense of stability and training demands. Adaptive and optimization-based controllers strengthen robustness but add computational burden and parameter sensitivity. FFC has been deployed across process control, electrical drives, fuel cells, engines, robotics, motion systems, power electronics, and energy systems. These applications consistently show improved tracking and robustness, though adoption is limited by reliance on models, calibration effort, and a lack of hardware validation. Signal acquisition and processing shape the stability and robustness of feedforward-augmented control architectures. A discussion is had reviewing recent advances in noise-aware estimation, delay-robust control, and filtered/learned inverse models to identify practical design strategies for maintaining reliable performance, focusing on medium and high frequency. To demonstrate practical benefits, a feedforward-augmented PID (i.e., feedforward control added to a PID closed loop system) with preview and anti-windup enabled transient testing on absorbing dynamometers, traditionally restricted to steady-state use. Combined with reinforcement learning controllers, this approach reduced error, expanded applicability, and offered a cost-effective alternative to motored dynamometers
A durability evaluation method for CFRP-reinforced circular hollow section joints in a neutral salt spray environment
Get PDFThe durability of carbon fibre-reinforced polymer (CFRP) strengthened steel structures is a critical issue affecting their long-term reliability in practical engineering applications. However, the degradation behavior and durability of CFRP-strengthened circular hollow section (CHS) joints have not been quantified. This study proposed a numerical analysis method for assessing the durability of CFRP strengthened CHS joints based on experiments. First, durability tests in a neutral salt spray environment and tensile failure tests were conducted on the adhesive and CFRP sheets to obtain moisture diffusion parameters and establish mechanical performance formulae. Static tests were conducted on unaged and aged CFRP-reinforced CHS T-joints. Then, FE models of bare and CFRP-reinforced CHS joints were developed. In the models of CFRP-reinforced joints, mechanical property degradation of the CFRP composite layers and the CFRP-to-steel bonding interfaces were considered. FE models of CFRP composite layers and the bonding interface were developed for mass diffusion analysis. A coupled diffusion-mechanical analysis program was proposed to predict the joint’s durability year, which was verified by experimental results. Finally, the effects of interface moisture diffusion coefficient, CFRP length, and number of CFRP layers on the durability year were analyzed. Suggestions were proposed to improve the durability performance of CFRP-reinforced CHS joints. The proposed method provides an effective tool for predicting the long-term performance of CFRP-reinforced CHS joints and supports durability design
Asymptotic analysis of the total quasi-steady state approximation for the Michaelis–Menten enzyme kinetic reactions
Get PDFWe consider a stochastic model of the Michaelis–Menten (MM) enzyme kinetic reactions in terms of Stochastic Differential Equations (SDEs) driven by Poisson Random Measures (PRMs). It has been argued that among various Quasi-Steady State Approximations (QSSAs) for the deterministic model of such chemical reactions, the total QSSA (tQSSA) is the most accurate approximation, and it is valid for a wider range of parameter values than the standard QSSA (sQSSA). While the sQSSA for this model has been rigorously derived from a probabilistic perspective at least as early as 2006 in [4] , a rigorous study of the tQSSA for the stochastic model appears missing. We fill in this gap by deriving it as a Functional Law of Large Numbers (FLLN), and also studying the fluctuations around this approximation as a Functional Central Limit Theorem (FCLT)
A Novel Continuous Control Set Model Predictive Control of Three-Phase Single-Stage Differential Boost Inverter
Get PDFThe three-phase differential boost inverter (DBI) is a specialized category of power inverters that provides single-stage boosting functionality, characterized by high efficiency, cost-effectiveness, and compact size. However, it is challenging to control due to its non-linearity and non-minimum phase characteristics. Specifically, when model predictive control (MPC) is applied, the non-minimum phase characteristics can lead to unstable internal dynamics. To solve this problem, this paper proposes a novel continuous control set MPC (CCS-MPC) method for the three-phase DBI. Based on the established predictive models of circuit currents and voltages, the appropriate duty cycle for the next sampling period can be predicted. An additional inductor current-based stability constraint is designed to achieve system stability. This control strategy significantly optimizes the dynamic performance and the second-order harmonics in the output currents. Compared with finite control set MPC (FCS-MPC), CCS-MPC features fixed switching frequency with higher steady-state accuracy and lower current ripple. Additionally, complex parameter design is avoided compared to PI-based control. Simulation and experiment are conducted to verify the efficacy of the proposed CCS-MPC for the three-phase DBI
A Multiwavelength Evaluation of AGN in the Post-Starburst Phase
Get PDFThe quenching of star formation is a crucial phase in galaxy evolution. Although active galactic nuclei (AGN) feedback has been proposed as a key driver of this transition, the lack of strong AGN in nearby quenching galaxies raises questions about its effectiveness. In this study, we investigate AGN activity in post-starburst galaxies (PSBs), star-forming galaxies (SFGs), and quiescent galaxies (QGs) at z < 0.2, using multiwavelength data from eROSITA/eFEDS (X-ray), WISE (mid-infrared), and FIRST (radio). We assess AGN incidence and strength across different stages and apply stacking techniques to undetected galaxies to recover average AGN properties. Comparisons between observed luminosity and that expected from star formation (L obs /L SF) show that PSBs are consistent with star formation dominating their radio and X-ray emission. Although PSBs exhibit a MIR AGN incidence rate twice that of SFGs, their estimated AGN luminosities are small compared to those of MIR AGN in the literature. PSBs overall do not display significantly enhanced AGN emission relative to mass-and redshift-matched SFGs and QGs. While the presence of obscured, low-luminosity AGN in PSBs cannot be excluded, such AGN, if present, could be fueled by residual gas from the preceding starburst and may not play a dominant role in quenching. Our findings suggest that AGN's role in quenching at low redshift is more subtle than violently removing the gas-the feedback is likely more "preventive" than "ejective"
Using AI for the documentation of intangible cultural heritage
Get PDFThis paper explores the potential roles AI could play in interpreting, documenting, preserving, and making accessible intangible forms of cultural heritage for future generations. The paper starts by analysing the changing role of documentation in collections and archives (primarily museum archives and/or archives that include artworks). The paper then investigates what these changes in documentation may mean for archives, introducing also the notion of a dynamic archive. Finally, the paper utilises ChatGPT to explore how AI defines documentation, how it states documentation can be used, and what research might be necessary to establish the responsible and trustworthy use of AI in this context. The two case studies explored through ChatGPT are Lynn Hershman Leeson’s Agent Ruby (1998-2002) and Blast Theory’s Cat Royale (2022). Our argument is that the use of AI in the documentation of intangible cultural heritage will impact not only its presentation, exhibition, and conservation, but also change the role that archives will play in years to come
Somaforming on an alien Earth
Get PDFThe realities of climate catastrophe increasingly threaten opportunities for multispecies liveability on this planet; Earth is becoming more alien every day through unequal intensities of weirding. We explore the conceptual provocations in the idea of ‘terraforming Terra’: that is, exploring the politics of transforming exoplanets – fabulated in the pages of science fiction – in contemporary empirical situations on an alien Earth. Gleaning insight from the speculative fiction of Becky Chambers in her 2019 novella To Be Taught, If Fortunate, we examine her concept of ‘somaforming’ in relation to terraforming. Chambers presents somaforming as a technology deployed to adapt bodies to alien planets, as an explicit alternative to terraforming, enabling human survival in hostile exoplanetary environments. We read somaforming with empirical reference to ongoing technoscientific efforts seeking to adapt bovine bodies to the imagined futures caused by global warming, in preparation for weird worlds to come. We analyse two scientific experiments that attempt to adapt cattle to the negative environmental impacts of climate change – respectively parasitism and heat stress – affecting animal welfare and agricultural productivity. While these somaforming practices each use a different technology transforming the cows’ body – through paint or gene editing – we argue that both illustrate the dangers of allowing ‘somaforming experiments’ to pre-empt an alien Earth, in its foreclosing of alternatives to ‘business as usual’
Local control of cellular proliferation underlies neuromast regeneration in zebrafish
Get PDFBiological systems are never in equilibrium, yet they maintain stability in the face of continuous external disturbances. A prime example of this is organ regeneration, during which organs are reliably rebuilt through controlled cellular proliferation. In this study, we employ a cell-based computational modelling approach to investigate the proliferative response of an organ after injury. We developed a minimal two-dimensional Cellular Potts Model (CPM) using empirical data from regenerating neuromasts in larval zebrafish. Remarkably, the CPM both qualitatively and quantitatively recapitulates the regenerative response of neuromasts following laser-mediated cell ablation. Assuming that cell proliferation is locally regulated by a delayed switch, we discovered that mitotic activity ceases once the type-dependent number of neighbouring cells exceeds a deterministic critical threshold. An intriguing corollary of our findings is that a local negative feedback loop among identical cells may represent a general mechanism underlying organ-level proportional homeostasis
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