Local Flexibility Research Articles

Implementation of combined planning and real-time control of proactive prosumer agents for local energy and flexibility markets

Implementation of combined planning and real-time control of proactive prosumer agents for local energy and flexibility markets

Structural Mass Spectrometry Captures Residue-Resolved Comprehensive Conformational Rearrangements of a G Protein-Coupled Receptor.

G protein-coupled receptor (GPCR) structural studies with in-solution spectroscopic approaches have offered distinctive insights into GPCR activation and signaling that highly complement those yielded from structural snapshots by crystallography or cryo-EM. While most current spectroscopic approaches allow for probing structural changes at selected residues or loop regions, they are not suitable for capturing a holistic view of GPCR conformational rearrangements across multiple domains. Herein, we develop an approach based on limited proteolysis mass spectrometry (LiP-MS) to simultaneously monitor conformational alterations of a large number of residues spanning both flexible loops and structured transmembrane domains for a given GPCR. To benchmark LiP-MS for GPCR conformational profiling, we studied the adenosine 2A receptor (A2AR) in response to different ligand binding (agonist/antagonist/allosteric modulators) and G protein coupling. Systematic and residue-resolved profiling of A2AR conformational rearrangements by LiP-MS precisely captures structural mechanisms in multiple domains underlying ligand engagement, receptor activation, and allostery, and may also reflect local conformational flexibility. Furthermore, these residue-resolution structural fingerprints of the A2AR protein allow us to readily classify ligands of different pharmacology and distinguish the G protein-coupled state. Thus, our study provides a new structural MS approach that would be generalizable to characterizing conformational transition and plasticity for challenging integral membrane proteins.

A multi-stage techno-economic model for harnessing flexibility from IoT-enabled appliances and smart charging systems: Developing a competitive local flexibility market using Stackelberg game theory

The increasing integration of renewable energy sources with power systems has led to greater uncertainties, heightening the need for more flexible services. Demand-side resources can provide significant flexibility cost-effectively, making it crucial to design new business models to harness their flexible capacities. Hence, this paper introduces a three-stage techno-economic framework designed to enhance the exploitation of flexible capacities from demand-side resources such as Internet-of-Things (IoT)-Enabled Appliances (IEAs), Battery-Integrated Rooftop Solar Panels (BIRSPs), and Electric Vehicle (EV) smart charging systems in the local flexibility market. The proposed framework operates in three stages. First, smart homes with IEAs, BIRSPs, and smart charging systems assess their flexibility and report it to their Microgrid (MG) operators. Next, MG operators optimize strategies to maximize market returns and report capacities to the Distribution System Operator (DSO). Finally, the DSO manages flexibility transactions based on MG inputs. A Stackelberg game theory model using a gradient-based method updates the coupling variables between market parties, ensuring convergence in the second and third stages within a decentralized space with limited information sharing. Implemented on a modified IEEE 69-node distribution system, the model fully utilizes the potential of smart homes, including IEAs, BIRSPs, and smart charging systems in the local flexibility market. It reduces the Upstream Network (UN) share in the local flexibility market by 56.86% and decreases DSO costs for energy balancing by 22.36%.

Parsing Dynamics of Protein Backbone NH and Side-Chain Methyl Groups using Molecular Dynamics Simulations.

Experimental NMR spectroscopy and theoretical molecular dynamics (MD) simulations provide complementary insights into protein conformational dynamics and hence into biological function. The present work describes an extensive set of backbone NH and side-chain methyl group generalized order parameters for the Escherichia coli ribonuclease HI (RNH) enzyme derived from 2-μs microsecond MD simulations using the OPLS4 and AMBER-FF19SB force fields. The simulated generalized order parameters are compared with values derived from NMR 15N and 13CH2D spin relaxation measurements. The squares of the generalized order parameters, S2 for the N-H bond vector and Saxis2 for the methyl group symmetry axis, characterize the equilibrium distribution of vector orientations in a molecular frame of reference. Optimal agreement between simulated and experimental results was obtained by averaging S2 or Saxis2 calculated by dividing the simulated trajectories into 50 ns blocks (∼five times the rotational diffusion correlation time for RNH). With this procedure, the median absolute deviations (MAD) between experimental and simulated values of S2 and Saxis2 are 0.030 (NH) and 0.061 (CH3) for OPLS4 and 0.041 (NH) and 0.078 (CH3) for AMBER-FF19SB. The MAD between OPLS4 and AMBER-FF19SB are 0.021 (NH) and 0.072 (CH3). The generalized order parameters for the methyl group symmetry axis can be decomposed into contributions from backbone fluctuations, between-rotamer dihedral angle transitions, and within-rotamer dihedral angle fluctuations. Analysis of the simulation trajectories shows that (i) backbone and side chain conformational fluctuations exhibit little correlation and that (ii) fluctuations within rotamers are limited and highly uniform with values that depend on the number of dihedral angles considered. Low values of Saxis2, indicative of enhanced side-chain flexibility, result from between-rotamer transitions that can be enhanced by increased local backbone flexibility.

Maximizing social welfare in local flexibility markets by integrating the value of flexibility loss (VOFL)

The increasing integration of Renewable Energy Sources (RESs) poses challenges due to their unpredictable nature. To address these challenges, flexible Distributed Energy Resources (DERs), such as Distributed Generators (DGs), Flexible Loads (FLs), and Energy Storage Systems (ESSs), have emerged in distribution networks. This paper proposes a linear programming formulation for optimizing flexibility provision in the Local Flexibility Market (LFM) to maximize Social Welfare (SW), contrasting with existing literature. The concept of the Value of Flexibility Loss (VOFL) is introduced to enable the Distribution System Operator (DSO) to optimize flexibility procurement, ensuring economic profitability for both providers and consumers. Additionally, the DSO can interchange flexibility with the Transmission System Operator (TSO) based on economic incentives. Numerical results demonstrate the accuracy and efficiency of the proposed model.

Molecular recognition with resolution below 0.2 angstroms through thermoregulatory oscillations in covalent organic frameworks

Crystalline materials with uniform molecular-sized pores are desirable for a broad range of applications, such as sensors, catalysis, and separations. However, it is challenging to tune the pore size of a single material continuously and to reversibly distinguish small molecules (below 4 angstroms). We synthesized a series of ionic covalent organic frameworks using a tetraphenoxyborate linkage that maintains meticulous synergy between structural rigidity and local flexibility to achieve continuous and reversible (100 thermal cycles) tunability of “dynamic pores” between 2.9 and 4.0 angstroms, with resolution below 0.2 angstroms. This results from temperature-regulated, gradual amplitude change of high-frequency linker oscillations. These thermoelastic apertures selectively block larger molecules over marginally smaller ones, demonstrating size-based molecular recognition and the potential for separating challenging gas mixtures such as oxygen/nitrogen and nitrogen/methane.

A matheuristic for active flexibility management of battery energy storage systems in the context of local flexibility markets

Flexibility has gained notoriety with the advancement of topics such as microgrids, renewable generation, distributed energy resources, and energy storage. Proposals like local flexibility markets (LFMs) demonstrate the growing interest in existing demand-side flexibility and the development of methods to access this resource. This work presents a matheuristic to managing battery energy storage systems (BESS) by controlling flexibility reserves of power and energy independently and parameterized through virtual control parameters. The system executes the processes of reserving flexibility, unlocking it, and utilizing it during day-ahead planning and in real-time operation to meet flexibility actions for increasing and reducing demand within LFMs. The management system's behavior is presented in an application case that demonstrates the system’'s ability to manage different flexibility levels. We present the impact of flexibility management on operating profitability, observing a lower loss of profitability in the allocation of power (kW) capacity and a higher loss of profitability in the energy (kWh) flexibility reserve. The method's effectiveness is presented through a set of proposed flexibility metrics, which allow for representing the available flexibility based on power, energy, and time duration of the parameterized demand response action.

Towards a positive energy balance: A comparative analysis of the planning and design of four positive energy districts and neighbourhoods in Norway and Sweden

Positive energy districts and sustainable plus energy neighbourhoods are developed in the European context to reduce energy use and greenhouse gas emissions from the building sector. The planning and development of positive energy districts and sustainable plus energy neighbourhoods is complex and requires collaboration between stakeholders and new measures to achieve high energy efficiency, local renewable energy generation, energy storage and flexibility, and energy sufficiency. This paper examines the implementation of energy measures in the planning and design of four positive energy district and neighbourhood development projects in Norway and Sweden. The paper compares the two different institutional and energy system contexts and how these affect the development of positive energy districts, focusing on the perspectives of the municipality and developers. Existing academic literature and positive energy district guidelines are used to develop an analytical framework for the planning and design of positive energy districts and sustainable plus energy neighbourhoods. Results highlight an early focus on energy ambitions, wide stakeholder involvement, and the importance of aligning interests between stakeholders and working interdisciplinary in the planning and design phases to find optimal energy measures. Both the building and the neighbourhood/district level are important to increase energy efficiency, energy sufficiency, and energy flexibility, and consequently lower the environmental impact of the whole development project.

Hierarchical robust Day-Ahead VPP and DSO coordination based on local market to enhance distribution network voltage stability

As distributed energy resources (DER) are increasing, a variety of business models and markets are appearing. Business models such as virtual power plants (VPPs) contribute to enhanced stability of the power system while improving the profits of participating resources. However, the uncertainty of the behavior of DERs and the resulting stability issues are a major barrier to DER deployment and require a coordination framework between grid operators and business models to overcome. Therefore, in this paper, a hierarchical robust day-ahead coordination of a VPP and distribution system operator (DSO) based on the local market is proposed to improve the voltage stability of the distribution network by considering the uncertainty of DERs. For fairness reasons, the contribution of DERs to the distribution system can be addressed by a market-based approach. Local markets are divided into local energy markets (LEM) and local flexibility markets (LFM), which can consider the uncertainty and profitability of DERs. First, the DER determines the seller and buyer status of the LEM based on its self- scheduling with expected prices and is matched based on a double-auction mechanism. At this time, the worst-case scenario of load and renewable energy generation predicted by the Gaussian process (GP) is considered. The mismatched amounts in the LEM are aggregated by the VPP and bid into the wholesale energy market (WEM) operated by the TSO (Transmission system operator). Subsequently, DSO operates a LFM that coordinates microgrid (MG) and VPP on the distribution grid to increase voltage stability. The LFM and WEM problems are considered as interval optimization in the form of mixed integer linear programming and are applied together. The flexibility supply resulting from the adjustment of VPP is compensated by a loss-sensitivity-based flexibility price. Since voltage stability exists in upper and lower bounds, the upper and lower bound of net load through GP-based forecasting is considered along with the linearized network constraints. The results are validated through Monte-Carlo simulation-based scenarios on IEEE benchmark system in MATLAB environment. As a result, it is proved that the proposed model improves the distribution network voltage stability and the profit of the participants.

Brain local stability and network flexibility of table tennis players: a 7T MRI study

Abstract Table tennis players have adaptive visual and sensorimotor networks, which are the key brain regions to acquire environmental information and generate motor output. This study examined 20 table tennis players and 21 control subjects through ultrahigh field 7 Tesla magnetic resonance imaging. First, we measured percentage amplitude of fluctuation across five different frequency bands and found that table tennis players had significantly lower percentage amplitude of fluctuation values than control subjects in 18 brain regions, suggesting enhanced stability of spontaneous brain fluctuation amplitudes in visual and sensorimotor networks. Functional connectional analyses revealed increased static functional connectivity between two sensorimotor nodes and other frontal-parietal regions among table tennis players. Additionally, these players displayed enhanced dynamic functional connectivity coupled with reduced static connectivity between five nodes processing visual and sensory information input, and other large-scale cross-regional areas. These findings highlight that table tennis players undergo neural adaptability through a dual mechanism, characterized by global stability in spontaneous brain fluctuation amplitudes and heightened flexibility in visual sensory networks. Our study offers novel insights into the mechanisms of neural adaptability in athletes, providing a foundation for future efforts to enhance cognitive functions in diverse populations, such as athletes, older adults, and individuals with cognitive impairments.

Enhanced wave absorption due to local flexibility on wide beams using mass-spring-damper scatterers

It is known that total absorption of flexural waves in a thin beam is possible through the use of monopole-dipole scatterers. In this study, we introduce a pair of identical monopole scatterers for near-total absorption of flexural waves in a thin and wide beam. Despite the two scatterers being both of the monopole type, the resonant modes of the scatterer pair exhibit monopole and dipole properties. By selecting the proper width for the beam, the two resonant modes degenerate, which leads to the total absorption. Although the beam is considerably wide, the frequency range of interest remains below the cut-on frequency of the n = 1 propagating mode, ensuring one-dimensional flexural wave propagation. Further simulations and theoretical analysis revealed that the degeneracy of the monopole and dipole modes results from their interaction with a higher-order localized flexural mode. The simulation results demonstrate absorption exceeding 99%, complemented by experimental data showing approximately 90% absorption.

A geographically disaggregated approach to integrate low-carbon technologies across local electricity networks

Meeting climate targets requires widespread deployment of low-carbon technologies such as distributed photovoltaics, heat pumps and electric vehicles. Without mitigating actions, changing power flows associated with these technologies would adversely impact some local networks. The extent of these impacts, and the optimal means of avoiding them, remains unclear. Here we use local-level data and network simulation to estimate variation in future network upgrade costs in over 40,000 geographical regions comprising all of Great Britain. We find that costs vary substantially between localities, and are typically highest in urban areas, and areas with highest deployment of heat pumps and electric vehicles. We estimate reductions in required upgrades associated with local flexibility, which vary substantially between localities. We show that using geographically disaggregated data to inform flexibility deployment across the country could reduce network upgrade costs by hundreds of millions of pounds relative to an approach that treats localities as homogeneous.

Free vibration Analysis of Beams with Functional Gradient Materials with Cracks

The article presents the development of a dynamic model for a functionally graded material (FGM) beam incorporating cracks. Initially, it assumes an exponential distribution of material properties along the thickness direction of the beam and simulates the opening crack using a zero-mass rotational spring model. This approach enables the calculation of bending stiffness and local flexibility at the cracked section. Subsequently, drawing upon Timoshenko beam theory and von Kármán geometric nonlinear theory, the study formulates the energy equation of the beam and establishes the partial differential control equations for the cracked FGM using Hamilton's principle. The method of separation of variables is employed to discretize the partial differential motion equations into ordinary differential motion equations. Beam functions serve as mode functions, whose unknown coefficients are determined according to the boundary and continuity conditions, thereby yielding the natural frequencies and mode shapes of the cracked FGM beam. Numerical analysis is conducted to evaluate the impact of boundary conditions, the relative position of cracks, and the length-to-thickness ratio on the natural frequencies of the cracked FGM beam.

Mathematical Modelling for Failure Analysis of Composite Drive Shaft Using Modal Flexibility and Curvature Method

Early damage identification in composite structures has attracted a lot of attention in post-failure examinations in recent years. In the research, torsional fatigue test of composite drive shafts has been done and numerical methodologies have been employed for the validation for premature failure using modal flexibility and modal curvature methods. Initially, the eigenvalue and eigenvectors of healthy and fractured drive shafts are evaluated using a numerical model and verified by fatigue experimental approach. Flexibility variance and the absolute curvature difference between the drive shafts that are fractured and those that are healthy are evaluated after mass normalization. Variations in absolute modal curvatures and variations in local flexibilities that are utilized to identify the existence, location, and severity of a drive shaft fracture. The position and severity of the fracture are predicted more precisely by the modal curvature approach than by the modal flexibility approach.

Hotspot Wizard-informed engineering of a hyperthermophilic β-glucosidase for enhanced enzyme activity at low temperatures.

Hyperthermophilic enzymes serve as an important source of industrial enzymes due to their high thermostability. Unfortunately, most hyperthermophilic enzymes suffer from reduced activity at low temperatures (e.g., ambient temperature), limiting their applicability. In addition, evolving hyperthermophilic enzymes to increase low temperature activity without compromising other desired properties is generally difficult. In the current study, a variant of β-glucosidase from Pyrococcus furiosus (PfBGL) was engineered to enhance enzyme activity at low temperatures through the construction of a saturation mutagenesis library guided by the HotSpot Wizard analysis, followed by its screening for activity and thermostability. From this library construction and screening, one PfBGL mutant, PfBGL-A4 containing Q214S/A264S/F344I mutations, showed an over twofold increase in β-glucosidase activity at 25 and 50°C compared to the wild type, without compromising high-temperature activity, thermostability and substrate specificity. Our experimental and computational characterizations suggest that the findings with PfBGL-A4 may be due to the elevation of local conformational flexibility around the active site, while slightly compacting the global protein structure. This study showcases the potential of HotSpot Wizard-informed engineering of hyperthermophilic enzymes and underscores the interplays among temperature, enzyme activity, and conformational flexibility in these enzymes.

Unraveling the Impact of Pesticide Exposure on Apis Honey Bees: An Investigation on Succinate Dehydrogenase Subunit A (SDHA) Inhibition Mechanisms

AbstractConcerns about pollinator health and the influence on agricultural ecosystems have developed as a result of pesticide‐caused population declines in honey bees. The research looked at the properties of the SDHA subunit of the enzyme Succinate dehydrogenase, which is important for energy production and mitochondrial function. The goal was to investigate the structural and functional characteristics of SDHA in several Apis bee species, as well as how pesticides can limit its activity. In silico analyses were conducted to understand the structural characteristics of the SDHA subunit, assess evolutionary conservation, analyze deformation energy, and investigate potential pesticide binding. Thirteen pesticides were subjected to molecular docking studies with the Apis SDHA subunit. The study revealed the stability and conserved nature of the SDHA subunit across different Apis sp. Deformation energy analysis highlighted regions of local flexibility, particularly in the active site and interdomain interfaces. Molecular docking analysis indicated that pesticides such as Carboxin, Clothianidin, and Dithianon potentially interfere with FAD binding, while Fipronil and Sulfoxaflor may disrupt both FAD and dicarboxylate binding. This research sheds light on pesticides′ probable inhibitory effects on SDH, a vital enzyme in honey bee energy production and mitochondrial function. The findings highlight the importance of stringent pesticide controls and long‐term pest management measures to protect pollinator numbers and ecosystem health.

Dynamic Response of the Tunnel Lining with a Circumferential Crack Subjected to a Harmonic Point Load

Cracks are one of the most common diseases of tunnel lining, and the structural dynamic response can be used to assess the health of a tunnel. Hence, this paper investigates the dynamic response of shield tunnel lining with a partly circumferential crack. The shield tunnel lining is regarded as a thin cylindrical shell and analyzed independently. The research methodology integrates the wave propagation method, the local flexibility matrix, the line spring model and the wave superposition principle. The results show that the position and depth of a partly circumferential crack can influence the natural frequency of the shield tunnel lining. Under the fixed-position load, as the distance from the monitoring point to the crack increases, the difference in displacement response amplitude between the undamaged and cracked linings diminishes. Moreover, deepening cracks enlarge the magnitude of amplitude differences. When the load approaches the crack, the radial amplitude difference first increases and then decreases as the monitor moves away from the crack. This finding helps determine the required monitor position. The displacement response of the selected monitor indicates that the closer the load position is to the crack, the larger the amplitude difference. The results aid in identifying the crack position and selecting corresponding load and monitor locations.

Establishing a hierarchical local market structure using multi-cut Benders decomposition

Local electricity markets (LEMs) such as peer-to-peer (P2P) and community-based markets allow prosumers and consumers to exchange electricity products and services locally. In order to coordinate electricity trading and flexibility services, this paper proposes a hierarchical prosumer-centric market framework with a hybrid LEM and a local flexibility market (LFM). Multi-cut Benders decomposition (MCBD) is employed to decompose the integrated hybrid LEM into a centralized P2P market and multiple community-based markets. The aggregators coordinate energy sources and demands of households in low voltage (LV) distribution networks (DN) as virtual power plants (VPPs) and engage in trading through a P2P market over the medium voltage (MV) DN. In addition, a modified MCBD (M-MCBD) approach is proposed to accelerate the convergence process. The LFM is operated by the distribution system operator (DSO) and is formulated as a mixed-integer nonlinear programming (MINLP) problem which is further relaxed to a mixed-integer second-order cone programming (MI-SOCP) problem. The case study demonstrates that aggregators were able to collaborate on trading within the hybrid LEM to minimize the costs incurred by prosumers within the network. Furthermore, the proposed M-MCBD method improves the scalability of the MCBD by enhancing its convergence speed and accuracy, as demonstrated by testing on problems of varying scales.

Structural change of the cytoplasmic N-terminus and S1 segment of voltage-sensing phosphatase reported by Anap.

Voltage-sensing phosphatase contains a structurally conserved S1-S4-based voltage-sensor domain, which undergoes a conformational transition in response to membrane potential change. Unlike that of channels, it is functional even in isolation and is therefore advantageous for studying the transition mechanism, but its nature has not yet been fully elucidated. This study aimed to address whether the cytoplasmic N-terminus and S1 exhibit structural change. Anap, an environment-sensitive unnatural fluorescentamino acid, was site-specifically introduced to the voltage sensor domain to probe local structural changes by using oocyte voltage clamp and photometry. Tetramethylrhodamine was also used to probe some extracellularly accessible positions. In total, 51 positions were investigated. We detected robust voltage-dependent signals from widely distributed positions including N-terminus and S1. In addition, response to hyperpolarization was observed at the extracellular end of S1, reflecting the local structure flexibility of the voltage-sensor domain in the down-state. We also found that the mechanical coupling between the voltage-sensor and phosphatase domains affects the depolarization-induced optical signals but not the hyperpolarization-induced signals. These results fill a gap between the previous interpretations from the structural and biophysical approaches and should provide important insights into the mechanisms of the voltage-sensor domain transition as well as its coupling with the effector.

Harnessing EU legal concepts for the energy transition on islands

Abstract The European Commission plans to achieve the decarbonization of dozens of European Union (EU) islands by 2030. This would reduce greenhouse gas emissions, lower the dependency of islands on imported fuels, and potentially reduce local energy prices. At the same time, it may accelerate the mainland’s own energy transition through the import of surplus energy from renewable sources, the provision of aggregated flexibility services, and the testing of both technologies and policies on islands for replication and adaptation on the continent. Although islands are not even a legal category per se in EU energy law, the existing legal framework already allows to harness various concepts to foster the energy transition of EU islands. This article reviews available legal qualifications and regimes such as small systems’ exemptions, energy communities, positive energy districts, and local flexibility markets in the context of the decarbonization of EU islands. Potentially, they could open many different ways to tailor local energy transitions, channelling local actions to accelerate the whole process.