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Input-Output Extension of Underactuated Nonlinear Systems
Get PDFIn this letter, we address the problem of re-targeting a commercial under-actuated robotic system to a higher dimensional output task. Commercial platforms are equipped with an on-board low-level internal controller that provides the user some virtual references inputs and cannot be replaced. Such controller may control in practice only a subset of the total degrees-of-freedom of the system. Our primary objective is to augment these systems by introducing supplementary inputs, attaining increased output capability. Integrating such additional inputs into the control framework introduces a layer of complexity, raising questions about the compatibility and cohesiveness of the overall system. We derive necessary and sufficient conditions under which it is possible to extend the controlled outputs by adding extra inputs when one is forced to keep the internal controller unmodified. We underscore the efficacy and universality of our proposed methodology through the presentation of two relevant examples
Opportunity recognition in the tension field of knowledge and learning:The case of converging industries
No full textKnowledge-based and learning perspectives alone explain opportunity recognition insufficiently. While knowledge forms the base, learning may help entrepreneurs in novel contexts. Interactions between them add complexity to the analysis of opportunity recognition. Even though many contexts require combinations of knowledge and learning, research on opportunity recognition in these contexts remains scarce. We address this gap with fuzzy-set qualitative comparative analysis (fsQCA) using data from 107 corporate entrepreneurs from converging industries. Converging industries offer a unique context to explore these complexities, requiring entrepreneurs to merge knowledge and learn from new fields. We identify three types with high levels of opportunity recognition: the “broad experienced adapter”, the “specific experienced adapter”, and the “experimenter”. Unlike a simple knowledge-based view suggests, we argue that knowledge is not always necessary. Entrepreneurs compensate for knowledge deficits by combining several learning capabilities. Configurational analysis enriches the theory of how multi-domain knowledge and learning contribute to opportunity recognition.</p
Diversification of flood risk management in the Netherlands:Implications for boundary judgement practices
Get PDFClimate change urges water managers in low-lying deltas to diversify their flood risk management (FRM) strategies. To reduce residual risks, they increasingly need to incorporate spatial and other measures. This has implications for the boundary judgements made by water authorities, that is, the implicit and explicit decisions about who and what is relevant to include and consider. To understand these implications, we assess the boundary judgements made by a Dutch regional water authority in two diversification-oriented frontrunner projects. We distinguish between three categories of judgements: (1) substantive: the scale, domains, time horizon and solutions that are considered; (2) participation: who is involved, to what extent and when; and (3) planning and decision: the flexibility of responsibilities, financing, planning and decision-making. Our results show that, in both projects, most of the boundary judgements became wider over time as a result of pressure from or interactions with actors from outside the water sector. Hence, despite its ambition to diversify flood risk strategies, the water authority continued to draw boundaries that were too tight to allow for meaningful collaboration with actors outside the water sector. Considering the importance of reconfiguring practices in transforming FRM, we recommend more engaged research into practices.</p
Mapping sustainable options in the fashion industry:A systematic literature review and a future research agenda
Get PDFThe fashion industry accounts for large impacts on the environment and social welfare, both on the consumers' and companies' sides. This study systematically reviews the literature on sustainable consumption in the fashion industry, clarifying sustainable fashion's meaning. Existing sustainable fashion solutions are investigated from consumers' behavior perspective and classified into three consumption phases, that is, (pre-)purchase, use, and post-use. 187 articles are included, and twenty-six sustainable solutions are identified across the consumption phases. These include techniques, features, services, and behaviors able to increase garment sustainability by mitigating negative impacts and ensuring product circularity by recycling and/or reusing at the product's end of life, representing promising strategies for fostering a transition toward sustainable fashion consumption practices. An innovative and comprehensive framework of sustainable fashion solutions is developed. Future research agenda and a sustainable offering inventory for marketers are provided.</p
Turán numbers of general star forests in hypergraphs
Get PDFLet F be a family of r-uniform hypergraphs, and let H be an r-uniform hypergraph. Then H is called F-free if it does not contain any member of F as a subhypergraph. The Turán number of F, denoted by exr(n,F), is the maximum number of hyperedges in an F-free n-vertex r-uniform hypergraph. Our current results are motivated by earlier results on Turán numbers of star forests and hypergraph star forests. In particular, Lidický et al. (2013) [17] determined the Turán number ex(n,F) of a star forest F for sufficiently large n. Recently, Khormali and Palmer (2022) [13] generalized the above result to three different well-studied hypergraph settings (the expansions of a graph, linear hypergraphs and Berge hypergraphs), but restricted to the case that all stars in the hypergraph star forests are identical. We further generalize these results to general star forests in hypergraphs.</p
A Kinetic Chemotaxis Model and Its Diffusion Limit in Slab Geometry
No full textChemotaxis describes the intricate interplay of cellular motion in response to a chemical signal. In the slab geometry, the motion takes place between two infinite membranes. Like in previous investigations, the asymptotic regime of high tumbling rates is of particular interest. This work provides local existence and uniqueness of solutions to the kinetic equation and shows their convergence towards solutions of a parabolic Keller–Segel model in the asymptotic limit. In addition, convergence rates with respect to the asymptotic parameter are established under additional regularity assumptions on the problem data. Particular difficulties in the analysis are caused by vanishing velocities in the kinetic model as well as the occurrence of boundary terms
CO2 Adsorption on Variably Hydrated Cation-Exchanged Montmorillonite-Rich Clays
Get PDFLayered swelling clay minerals like montmorillonite (MMT) can competitively and synergistically adsorb CO2 and H2O in their interlayer galleries. This work examines how different interlayer cations, relative humidity levels (and amount of cosorbed H2O), and (de)hydration history affect CO2 adsorption on MMT and MMT-rich bentonite at near-ambient pressure and temperature. For CO2 to be adsorbed, the MMT requires either large (e.g., Cs+) or hydrated interlayer cations to provide a sufficiently wide interlayer gallery, and must not have too much H2O adsorbed competitively with CO2. Na-MMT and initially anhydrous Mg- and Ca-MMT studied under increasing relative humidity conditions adsorb little CO2. However, Mg- and Ca-MMT can effectively adsorb CO2 if first hydrated and then mildly dried such that the cations remain hydrated while the competitively adsorbed excess H2O is removed. Because of their high stability and the favorable shape of their CO2 adsorption isotherms, low-cost (near-)natural Mg- and Ca-bentonite can be used for (cyclic) CO2 adsorption and separation purposes, similar to the more expensive Cs-bentonite
Unveiling energy poverty risk:A multidimensional analysis of the heat-or-eat dilemma
Get PDFLow-carbon transition can put citizens at risk of energy poverty, and it is crucial to understand why. Energy poverty is a multidimensional phenomenon. Vulnerable households might need to choose between accessing basic nutritional needs and energy: a high expenditure share in food and energy can lead to difficulties in energy affordability, leading to the heat-or-eat dilemma. This research examines the risk of such a dilemma through three dimensions, in Europe. First, at a regional dimension, poorly implemented climate responses might worsen households' accessibility to basic services. Here, food and energy systems are geographically analysed to unearth regions where households are exposed to energy poverty. Second, in a socioeconomic and demographic dimension, not all population groups are equally vulnerable to energy poverty, as their characteristics shape their vulnerability. Therefore, the disposable income of different population groups is scrutinised. Third, changing citizens' lifestyles might increase the risk of energy poverty for those unable to adapt to new living patterns, exposing the need to focus on a lifestyle dimension. As lifestyles are defined by the expenditure share of households in different domains, such as food and energy, expenditure patterns are used to identify households at risk of energy poverty due to exacerbated food and energy expenditure. Ultimately, the results are combined into an overarching composite index, the Heat-or-Eat Risk Index. The data identifies European regions with a higher energy poverty risk due to changes in the energy and food domains, informing the assessment of just and equitable climate responses in European regions
Molecular-scale in-operando reconfigurable electronic hardware†
Get PDFIt is challenging to reconfigure devices at molecular length scales. Here we report molecular junctions based on molecular switches that toggle stably and reliably between multiple operations to reconfigure electronic devices at molecular length scales. Rather than static on/off switches that always revert to the same state, our voltage-driven molecular device dynamically switches between high and low conduction states during six consecutive proton-coupled electron transfer steps. By changing the applied voltage, different states are accessed resulting in in operando reconfigurable electronic functionalities of variable resistor, diode, memory, and NDR (negative differential conductance). The switching behavior is voltage driven but also has time-dependent features making it possible to access different memory states. This multi-functional switch represents molecular scale hardware operable in solid-state devices (in the form of electrode–mono-layer–electrode junctions) that are interesting for areas of research where it is important to have access to time-dependent changes such as brain-inspired (or neuromorphic) electronics.</p
