bluuebunny/crossref_metadata_2025_split huggingface dataset:
Online Learning With Joint State and Model Estimation
Authors: Götte Ricarda‐Samantha , Timmermann Julia 
Published: December 2024

ABSTRACTModel‐based state observers require high‐quality models to deliver accurate state estimates. However, due to time or cost shortage, modeling simplifications or numerical issues, models often have severe inaccuracies that may lead to insufficient and deficient control. Instead of attempting to iteratively model these deviations, we address the challenge by the concept of joint estimation. Thus, we assume a linear combination of suitable functions to approximate the inaccuracies. The parameters of the linear combination are supposed to be time invariant and augment the model's state. Subsequently, the parameters can be identified simultaneously to the states within the observer. Referring to the principle of Occam's razor, the parameters are claimed to be sparse. Our former work shows that estimating states and model inaccuracies simultaneously by a sparsity promoting unscented Kalman filter yields not only high accuracy but also provides interpretable representations of underlying inaccuracies. Based on this work, our contribution is twofold: First, we apply our approach finally on a real‐world test bench, namely a golf robot. Within the experimental setting, we investigate closed loop behavior as well as how suitable functions need to be chosen to approximate the inaccuracies in a physically interpretable way. Results do not only provide high state estimation accuracy but also meaningful insights into the system's inaccuracies. Second, we discuss and establish a method to automatically adapt and update the model based on collected data of the linear combination during operation. Examining past parameter estimates by principal component analysis, a moving window is utilized to extract the most dominant functions. These are kept characterizing the model inaccuracies, while nondominant functions are automatically neglected and refilled with novel function candidates. After analysis and rebuilding, this updated function set is subsequently fed back into the joint estimation loop and deployed for further estimation. Hence, we give a holistic paradigm of how to analyze and combat model inaccuracies while ensuring high state estimation accuracy. Within this setting, we once more investigate closed loop behavior and yield promising results. In conclusion, we show that the proposed observer provides a helpful tool to guarantee high estimation accuracy for models with severe inaccuracies or for situations with occurring deviations during operation, for example, due to mechanical wear or temperature changes.
Vector‐Valued Nonconforming Finite Element for Surface Flows
Authors: Mehlmann Carolin 
Published: December 2024

ABSTRACTIn the recent years, there has been an increasing interest in the analysis of finite element methods for vector‐valued flow problems on curved geometries. In this contribution, we derive an error analysis for a vector‐valued Crouzeix–Raviart element. The derivation is performed on the vector‐valued Laplace problem, which includes the symmetrical strain rate tensor, an important operator for modeling flow problems. The approximation of the strain rate tensor with the Crouzeix–Raviart element leads to oscillations in the velocity field due to a nontrivial kernel. We derive a stabilized form of the equation and present optimal error bounds in the ‐norm for the Crouzeix–Raviart finite element. The theoretical findings are supported by numerical results.
A predictive model for electrical conductivity of polymer carbon black nanocomposites
Authors: Abdollahi Fereshteh , Mohammadi Mohsen , Zare Yasser , Munir Muhammad Tajammal , Rhee Kyong Yop , Park Soo‐Jin 
Published: December 2024

AbstractAlthough many studies have investigated the percolation threshold and conductivity in the polymer carbon black (CB) nanocomposites (PCBs) by experimental data, the modeling in this field is a topic previously overlooked in literature. This paper suggests a simple equation for percolation threshold in PCBs by the surface properties of polymer and CB a well as interphase depth (t). Also, the electrical conductivity of PCBs is simulated by CB radius (R), tunneling distance (λ) and interphase depth. The offered model is validated by experimented findings of numerous samples and parametric examinations. A thicker interphase and a higher interfacial tension positively reduce the percolation onset. The smaller CBs, lower percolation threshold, and smaller tunnels enhance the electrical conductivity of PCBs. The low percolation threshold of 0.01 is obtained by the low R (15 nm) and the thick interphase (35 nm). Also, R = 15 nm and t = 35 nm maximize the PCB conductivity to 6 S/m. These results signify the important roles of CB radius and interphase depth in the percolation threshold and conductivity of PCBs. In addition, network fraction (f) of 0.7 and λ = 1 nm produce the uppermost PCB conductivity of 1.6 S/m, but the system is insulated at CB network fraction less than 0.35 or tunneling distance more than 2 nm. Therefore, high network fraction and low tunneling distance are needed to enhance the conductivity of PCBs.Highlights
An equation for percolation onset of PCBs is proposed by CB radius and interphase depth.
The offered model is validated by experimented data and parametric examinations.
A thicker interphase and a higher interfacial tension positively reduce the percolation onset.
Smaller CBs, lower percolation onset, and smaller tunnels enhance the PCB conductivity.
CB radius and interphase depth significantly manage the conductivity of PCBs.
Enhanced microwave absorption and mechanical properties of conformal composite with gradient graphene honeycomb
Authors: Luo Bailu , Liu Yujie , Li YiBin 
Published: December 2024

AbstractThis study aims to develop a novel conformal composite structure with integrated stealth and load bearing. Specifically, the stealth sandwich composite with graphene honeycomb (SCGH) was proposed and used as the electromagnetic (EM) window of overall structure. The multi‐layered honeycomb with gradient impedance was designed and prepared through the chemical self‐assembly process and the vacuum infusion process. The EM reflectivity at different incident angles was experimentally tested to reveal the absorption properties of the SCGH. The measured results show that the SCGH exhibits excellent stealth characteristics. Across the frequency range of 2–18 GHz, the reflection loss (RL) of the SCGH is less than −10 dB. The maximum RL of SCGH is −63 dB at 7.3 GHz. In addition, the SCGH is not very sensitive to the incident angle of EM waves. The uniform loading test was conducted on the overall structure with open window (SOW), and the deformation characteristics and typical damage modes are revealed. The local stiffness of the SOW was reduced by the open window, leading to significant deformation in the window corner areas. The primary damage mode under uniform loading is fiber fracture, occurring at the four window corners due to large deformation. This study provides reference and basis for structural design and performance analysis of conformal composite with integrated stealth and load bearing.Highlights
Designed and prepared the composite structure with conformal window.
Revealed the stealth performance and reflectivity at different incident angles of structure.
Investigated the mechanical performance and failure mechanism of the structure.
PVDF‐based high‐energy‐storage dielectrics by introducing insulating layer on the surface of metal‐organic frameworks
Authors: Qu Can , Long Yiting , Zhang Xuemei , Liu Jingsong , Pu Linyu , Huang Xu 
Published: December 2024

AbstractIn this paper, UiO‐66 nanoparticles were synthesized through the hydrothermal synthesis technique. Subsequently, a series of metal‐organic framework/polyvinylidene fluoride (MOF/PVDF) composite films were produced via a solution‐casting approach. The dielectric properties of UiO‐66/PVDF (U/P) composite are improved with the addition of UiO‐66. The dielectric constant (ɛr) of 20 wt% U/P composite film at 102 Hz is 11.20, 1.44 times that of pure PVDF film (ɛr = 7.78). However, the breakdown strength (Eb) was only 95 kV mm−1. To solve the problem of sharp decline in Eb, TiO2 with a wide band gap was introduced to form an insulating layer on the surface of UiO‐66. This reduces the difference in electrical properties between the filler and PVDF, hinders the formation of the conductive path within the composite, reduces leakage current, and increases Eb. Compared with the U/P composite, the ɛr and Eb of TiO2@UiO‐66/PVDF (T@U/P) composite film are increased, and the dielectric loss (tanδ) and leakage current density (J) are decreased. The energy storage density (Ue) of 10 wt% T@U/P composite film is 4.51 J cm−3 and the charge and discharge efficiency (η) is 84.61% at 150 kV mm−1. These results indicate that the dielectric properties of UiO‐66 can be significantly enhanced by using titanium dioxide as an insulating layer.Highlights
By introducing UiO‐66, the ɛr of PVDF material is improved.
Modifying UiO‐66 with TiO2 can improve its breakdown strength significantly.
The Ue of the T@U/P‐10 composite modified with UiO‐66 is 4.51 J cm−3.
Water desalination using CaCO3/blend of polyphenylene oxide and polystyrene mixed matrix membranes in a direct contact membrane distillation (DCMD) unit
Authors: Pakizeh Majid , Rahimnia Rasoul 
Published: December 2024

AbstractThe present study examines the impact of integrating hydrophobic calcium carbonate (CaCO3) nanoparticles into porous membranes composed of a polyphenylene oxide (PPO)/polystyrene (PS) blend on desalination performance. CaCO3 filler was added to polymeric solution at concentrations of 2–10 wt% and prepared samples were characterized using ATR‐FTIR, FE‐SEM, EDX, AFM, liquid entry pressure (LEP), contact angle, and porosity measurement analyzes. Surface porosity of the samples was determined by the Digimizer software. The desalination performance of the membranes was evaluated using a laboratory‐scale direct contact membrane distillation (DCMD) unit. Results showed that nanoparticles did not affect the membrane's finger‐like structure but altered the surface pore size and porosity. Adding 10 wt% CaCO3 to the membrane caused the maximum surface pore size to decrease from 35.4 to 17.4 nm, leading to an increase in the LEP value from 0.9 to 2.1 bar. The MMM with 2 wt% CaCO3 nanoparticles exhibited the highest flux of 34.92 kg/m2h (~20% higher than pure membrane) due to its higher surface porosity, also the rejection was achieved above 99.9%. Physical properties along with thermal efficiency and temperature polarization coefficient of the prepared membranes were compared. Fouling properties and scaling of the prepared membranes were investigated using different organic and inorganic solutions. Results showed that fouling resistance of samples containing CaCO3 filler was improved.Highlights
Adding hydrophobic CaCO3 to neat polymer, enhanced DCMD performance.
The fouling and scaling resistance of the MMM were better than neat polymer.
MMMs showed a rejection higher than 99.5% due to non‐wetting effect of filler.
Maximum surface porosity and flux was observed for 2.0 wt% of filler loading.
Maximum flux was observed in sample with 2.0 wt% filler loading.
Dynamics of thrombin generation: Filling the gap between the system pharmacology theory and clinical practice in clinical pharmacology and therapeutics
Authors: Ruiz Leire , Jaramillo Sebastian , Calvo Andrea , Torrente M. A. , Tassies Dolors , Reverter J. C. , Blasi Annabel , Troconiz Iñaki 
Published: December 2024

AbstractMathematical models of thrombin generation (TG) that have been developed are based on a systems biology approach. Although this approach provides important information about the coagulation system, its clinical applicability is limited by its complexity and number of input variables required. The aim of this study was to develop a semimechanistic model able to describe TG in trauma and control patients. A dataset containing longitudinal data of TG assays and coagulation factors from 40 trauma patients and 20 control patients was used for model building. The model considered three fundamental processes: the degradation of tissue factor (TF) through a first‐order process, the activation of factor II by the TF through a first‐order process, and the degradation of thrombin through a first‐order process. Model fitting was performed using a nonlinear mixed‐effects approach. The condition of the patient (trauma and control) and coagulation factors were modelled as covariates. Model building demonstrated the presence of two additional processes that improved the predictive capacity of the model: the activation of factor II by TF governed by a second‐order constant and, a mechanism of factor II activation by TF characterized by a 7‐compartment transit chain governed by a second‐order constant. In the covariate model only the inclusion of patient condition was significant. Model evaluation demonstrated excellent performance in describing the temporal pattern of TG in trauma and control patients. Thrombin generation can be adequately modelled using a semimechanistic approach. Its application in practice could help to better assess the risk of hemorrhage and/or thrombosis in different settings.
Finite‐Time Observer Based Prescribed Performance Robust Control for Position Stabilization of Offshore Gangway Ends
Authors: Li Meng , Du Jialu 
Published: December 2024

ABSTRACTConsider an offshore gangway subject to mathematical model parameter uncertainties and disturbance uncertainties. A finite‐time observer (FTO) is designed to estimate the motion states of the gangway end (GE) and the total uncertain nonlinear disturbances lumped by the parameter uncertainties and disturbance uncertainties. The bandwidth of the FTO is a function of the GE position estimation error and a prescribed performance function and is time‐varying, and thus our designed FTO does not rely on the bounds of the derivatives of the total uncertain nonlinear disturbances compared with conventional FTOs. Whereby, according to the idea of the active disturbance rejection control, we develop a prescribed‐performance robust control law (PPRCL) for GE position stabilization such that the position stabilization error can converge into a prescribed tolerance steady‐state band in a finite settling time. Simulation results with comparisons show the robustness and the advantage of our developed PPRCL.
Charge Dynamic Interface Z‐Scheme on r‐GO–WO3–α‐Fe2O3 Composite Surface for Hydrogen Production
Authors: Haider Rida Shahzadi , Sajjad Shamaila , Leghari Sajjad Ahmed Khan , Khan M. Yaqoob , Shahzad Khurram 
Published: December 2024

AbstractN‐type thin films of semiconductors WO3, α‐Fe2O3, and nanocomposite structures of WO3–α‐Fe2O3, and WO3–α‐ Fe2O3–r‐GO were prepared on FTO substrates using spray deposition. The optical, morphological, structural, crystallinity, and composition properties were studied by UV–visible spectroscopy, SEM, TEM, XRD, and EDS. Photoelectrochemical efficiency was assessed in a three‐electrode cell assembly and validated through various electrochemical measurements. The improved light absorption capacity of WO3–α‐Fe2O3–r‐GO composites is due to synergistic effect and hierarchical nanostructures with ultrahigh surface areas enhanced by the incorporation of r‐GO. The reduction potentials of WO3 and Fe2O3 can be tuned by controlling morphology and particle size. WO3 as a photoanode suffers from volumetric and structural changes during redox reactions, leading to instability and decreased photocurrent response. Hematite is a promising candidate for PEC water splitting due to its lower bandgap (2.0–2.2 eV) and excellent electrochemical stability in electrolytes. However, it has drawbacks such as low quantum efficiency and short hole diffusion length. The combined benefits of r‐GO, hematite, and WO3 in WO3–α‐Fe2O3–r‐GO composite effectively detect electron dynamics across WO3–α‐Fe2O3 interface with r‐GO serving as a mediator to study charge dynamics at interface. The critical role of r‐GO in enhancing electrochemical performance of nanocomposites has been well established.
Contributing to the Sustainable Development of New Energy Materials: Current Research Status and Future Fate of Conductive Agents for Lithium Iron Phosphate Batteries
Authors: Cui Qingyuan , Wu Huanhuan , Qu Guangfei , Li Junyan , Wu Feihui 
Published: December 2024

AbstractIn the face of the global resource and energy crisis, new energy has become one of the research priorities, and lithium iron phosphate (LFP) batteries are giving rise to a new generation of high‐power lithium‐ion batteries. Carbon‐based materials, as important basic materials, are widely used in various fields with their excellent physicochemical properties, which greatly support the research of dual‐carbon policy. Traditional conductive agents, however, have gradually shown limitations in certain applications of high‐performance lithium‐ion batteries. The development and application of new highly conductive carbon‐based conductive agents has become a mainstream trend in the research of anode conductive agents for lithium‐ion batteries. At present, the conventional conductive agent cannot meet the development needs of high‐performance lithium‐ion batteries. The research and application of new high‐conductivity carbon‐based conductive agents has become the main stream of research and trends in conductive agents for the cathode of lithium‐ion batteries. In this paper, carbon black (CB), carbon nanotubes (CNTs) and graphene are taken as typical materials for carbon‐based conductive agents for LFP batteries as examples, which are individually combined as LFP cathode conductive agents and carbon doped composites, and the synthesis method and action mechanism are discussed. The future research focus on lithium‐ion batteries and new carbon‐based cathode conductors is discussed, providing a reference for the further development of cathode conductors.
Assessing the Interactions in Atmospherically Relevant Sulfuric Acid‐Carboxylic Acid Clusters
Authors: Li Luqi , Xu Jianzhi , Li Ya‐Ke , Hou Gao‐Lei 
Published: December 2024

AbstractClusters of atmospheric precursor molecules, like sulfuric acid, bisulfate, and organic carboxylic acids, are important embryos for the formation of aerosol particles, further impacting both the earth radiation budget, cloud formation, and daily life. In this work, we studied theoretically the structures, energetics, and interactions of a cluster formed between HSO4– and acetic acid: HSO4–•H+•CH3COO–, which stands for the uncertain location of the proton, either on HSO4– end or on CH3COO– end. We checked the performance of second‐order Møller–Plesset perturbation theory (MP2) and several density functional theory methods, including BP86, PW91, PBE0, B3LYP, M06‐2X, CAM‐B3LYP, ωB97XD, and B2PLYP with both double‐ζ and triple‐ζ basis sets. We found that overall M06‐2X has good performance for the structures and energetics, and is suggested to be the choice for calculating similar kind of aerosol clusters, but B3LYP also has acceptable performance for optimizing the structures, in particular when dispersion corrections are included. We also found that HSO4–•H+•CH3COO– has two almost energy degenerate hydrogen bonded isomers, that is, HSO4–(CH3COOH) and H2SO4(CH3COO–), and energy decomposition analysis revealed that electrostatic interaction dominates the hydrogen bonding interactions for both isomers, followed by exchange and orbital interactions.
Computational Assessment of Atom Transfer Radical Polymerization in Thermosensitive Poly(Ethylene‐Glycol)‐block‐Poly((2‐(Dimethylamino)Ethyl‐Methacrylate) Copolymer
Authors: Kurniawan Muhammad Arsyik , Salmahaminati Salmahaminati , Kansız Seyithan , Topel Önder 
Published: December 2024

AbstractMolecular modeling currently plays an important role in chemistry, providing predictions about the structure and properties of chemical compounds in the design and development of new materials. Herein, the thermosensitive block copolymer poly(ethylene‐glycol)‐block‐poly((2‐dimethylamino)ethyl methacrylate) (PEG‐b‐PDMAEMA) was synthesized using atom transfer radical polymerization (ATRP). The structural properties and energy species of the polymer have been evaluated through theoretical studies using density functional theory (DFT). In particular, the electronic properties of the polymers, based on the composition of methacrylate monomers, have been evaluated through the HOMO‐LUMO gap energy, which allows for the description of the global chemical reactivity of the molecules. The electrostatic potential map of the polymer indicates that the oxygen and nitrogen atoms of the PEG‐b‐PDMAEMA polymer are the most effective sites for intermolecular interactions. The nature of interactions in polymer molecules, including steric repulsion, hydrogen bonding, and Van der Waals interactions, was analyzed using the Reduced Density Gradient (RDG) method.
Decoding the Potential of HRAS2 i‐Motif DNA Promoter to Become a Pinpoint Target by Phytomedicine Naringenin
Authors: Bag Sagar , Ghosal Souvik , Bhowmik Sudipta 
Published: December 2024

AbstractCytosine‐rich i‐motif (iM) DNA tetraplexes can influence oncogenic transcription and developing phytomedicines for iMs is a viable approach for cancer and other disease treatments. Although natural compounds have been studied as iM binding ligands for anticancer drug discovery, research on the structure‐interaction link between iM and ligand, like the influence of noncoplanar configurations on iM‐ligand binding, is rarely explored. Naringenin (NAR) have gained attention for their potential medicinal properties including high potency and minimal cytotoxicity. Our extensive biophysical and thermodynamic investigations have revealed that NAR interacted preferentially with HRAS2 iM compared to other experimental iMs. This research indicates that it is feasible to regulate gene expression by targeting HRAS2 iM with NAR, which might be beneficial in the development of anticancer medicines. The novel mechanical characteristics of NAR for HRAS2 iM may be important in disease treatments, providing critical insights for the future discovery of drugs with unique therapeutic attributes.
A Focused Review on Oxidation of Hydrazones Using Hypervalent Iodine Reagents
Authors: Sihag Monika , Kinger Mayank , Aneja Deepak Kumar 
Published: December 2024

AbstractHydrazones are described as synthetic equivalents to the carbonyl group and possess high synthon value. Herein, we compile the oxidative transformation of hydrazones using ecologically and economically benign hypervalent iodine reagents of the last decade. In this field, the development of C─H functionalization reactions leading to the formation of heterocycles or functionalized hydrazones is a major advancement in recent years. The oxidative properties of hypervalent iodine reagents are exploited to form many bioactive heterocycles (pyrazole, pyrazoline, pyridazine, 1,2,4‐triazole, 1,2,3‐tiazole, 1,3,4‐oxadiazole, tetrazine, tetrazole, pyrrole) through intramolecular or intermolecular C─N, C─O, or N─N coupling. Functionalized heterocycles are also afforded via tandem cascade group transfer/cyclization reactions. The transfer of perfluoroalkyl, sulfoximidoyl, aryl, and halogen groups is achieved using hypervalent iodine reagents as group donors or oxidants in combination with other group‐donating agents. The Togni reagent is the preferred choice for trifluoromethyl group donation, with or without a metal catalyst. Moreover, rearrangement reactions such as acyl migration and the diazotization of hydrazones are also achieved.