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Model-based reconstruction in MPI accounting for field imperfections
No full textTo date a system matrix has to be obtained through a tedious calibration measurement when employing a system matrix-based reconstruction in magnetic particle imaging. This problem can be effectively addressed by model-based reconstruction, which takes into account both particle and scanner parameters. In this study, we focus on the scanner parameters and in particular on the fact that the fields of experimental systems are imperfect. For experimental Lissajous-type data we show that the modeling error can be substantially reduced by about 18 % by incorporating field imperfections in both the transmit and receive coils
Linkers in Action: Exploring Fusion Enzymes for Oxyfunctionlizations in Non-Conventional Media Through Experiments and Simulations
No full textBaeyer–Villiger monooxygenases (BVMOs) are key for the selective oxidation of ketones into diverse (cyclic) esters. However, challenges like oxygen and cofactor dependence and substrate/product inhibition hinder their broader application. To address some of these issues, nonconventional media have been applied; still, they lack certain water required for enzyme hydration and cofactor regeneration, reducing activity and/or stability. Fusion approaches enable efficient cofactor recycling by shortening the diffusion distance between enzyme active sites in cascades, especially under low-water conditions. Trial-and-error linker design and time-intensive construction of fusion enzymes substantially slow down the development of fusion enzymes. In this study, we present the work on the fusions of cyclohexanone monooxygenase (CHMO) and alcohol dehydrogenase (ADH) with linkers owing varying lengths and flexibility in both orientations in nonconventional media, focusing on understanding the effects of linkers on the structural and catalytic properties of fusion enzymes. As such, 12 new fusion enzymes were constructed and evaluated regarding the kinetics, specific activity, and stability, identifying the optimal ones for the linear oxyfunctionlization cascade in aqueous–organic biphasic systems. The conformation and flexibility of linkers and the spatial arrangement of fusion enzymes were studied with simulations, which provides a deep understanding of linkers’ influence and offers insights into the rational design of fusion enzymes
Highly efficient phosphate extraction from water using bio-composites of nano zero valent iron supported on orange peel powder (nZVI@OPP): performance evaluation and mechanistic insights
No full textIn recent times, nZVI composites have been developed as environmentally friendly adsorbents to tackle the issue of eutrophication in freshwater bodies. Herein, we synthesized nano zero valent iron loaded orange peel powder (nZVI@OPP) in different proportions (1:1, 1:3, 1:5, and 1:10) and investigated its PO43− elimination potential from water. Among them, nZVI@OPP (1:5) composite presented excellent PO43− removal performance (93.3%) comparable to that of 1:1 (100.0%) and 1:3 (98.9%), and therefore was selected for further analysis. The physicochemical properties of nZVI@OPP (1:5) also showed porous and irregular surface with more available sorption sites and reactive functional groups than planar and crystal surface of raw OPP, as revealed by SEM–EDX, XRD, FT-IR, and elemental mapping. The optimum conditions (nZVI@OPP (1:5) dosage: 2 g/L, contact time: 60 min, pH: 7, initial PO43− concentration: 10 mg/L, and temperature: 298 K) indicated 93.3% PO43− removal from simulated water samples. Based on higher R2 values, PSO kinetic and Langmuir isotherm models showed better fitting with PO43− sorption data. Moreover, various coexisting anions posed a negative impact on PO43− removal in the given order: NO3− < SO42 < Cl− < mixed anions, while no significant impact of thermal variations on PO43− removal was observed. The spent nZVI@OPP (1:5) also showed reasonable reusability potential when removing PO43− from aqueous solution. The dominant PO43− removal mechanisms including physisorption, chemisorption, ligand exchange, and complexation reactions were identified. In general, the current study provides new insights into the importance of selecting appropriate mixing proportion of nZVI and OPP, with the potential of extracting maximum PO43− content from water considering economic and waste management perspective
Exploring localization in nonlinear oscillator systems through network-based predictions
No full textLocalized vibrations, arising from nonlinearities or symmetry breaking, pose a challenge in engineering, as the resulting high-amplitude vibrations may result in component failure due to fatigue. During operation, the emergence of localization is difficult to predict, partly because of changing parameters over the life cycle of a system. This work proposes a novel, network-based approach to detect an imminent localized vibration. Synthetic measurement data are used to generate a functional network, which captures the dynamic interplay of the machine parts, complementary to their geometric coupling. Analysis of these functional networks reveals an impending localized vibration and its location. The method is demonstrated using a model system for a bladed disk, a ring composed of coupled nonlinear Duffing oscillators. Results indicate that the proposed method is robust against small parameter uncertainties, added measurement noise, and the length of the measurement data samples. The source code for this work is available at C. Geier [(2024). “Code for paper Exploring localization in nonlinear oscillator systems through network-based predictions,” Zenodo. https://doi.org/10.5281/zenodo.12611988]
Developing a protocol for aligning and correlating seismocardiography with echocardiography
No full textSeismocardiography (SCG) monitors health metrics through body surface vibrations from heart activity. The BEAT experiment required echocardiography (ECHO) to correlate SCG signals with cardiac events. Since no standardized ECHO protocol existed, the authors developed one. The protocol focused on recording mitral and aortic valve openings and closings using multiple ECHO modalities for accuracy, ensuring usability, comfort, and efficient data collection. It was tested on healthy subjects and allowed post-hoc analysis of cardiac function. This standardized protocol aims to enhance comparability across SCG studies and offers a reliable method for correlating SCG signals with cardiac events
Randomized algorithms to generate hypergraphs with given degree sequences
No full textThe question whether there exists a hypergraph whose degrees are equal to a given sequence of integers is a well-known reconstruction problem in graph theory, which is motivated by discrete tomography. In this paper we approach the problem by randomized algorithms which generate the required hypergraph with positive probability if the sequence satisfies certain constraints
Introducing a tool for synthetic defect image data generation: enhancing industrial surface inspection
No full textVisual surface defect detection in complex scenarios remains a manual endeavor in industrial inspection. Stateof- the-art machine learning approaches promise to automate this task through machine vision; however, they require substantial, suitable training data to be effectively trained. For industrial products, such data are often unavailable for several reasons, including the rarity of certain defects or their manifestations. This paper introduces a tool to generate synthetic data for training machine vision systems using rendering techniques. Our tool allows for targeted manipulation of process parameters throughout the rendering chain, including scene composition involving object, camera, and lighting, defect generation, placement, and material generation. This enables an exploration of the impacts along the rendering pipeline and facilitates selecting an appropriate data set for specific inspection tasks. We demonstrate our tool’s effectiveness by applying models trained on our synthetic data to a real-world inspection task
Coordination of Demand-Side Flexibility Resources for Preventive Congestion Management in Distribution Systems
No full textA coordination function (CoF) is proposed as a measure of preventive congestion management in the distribution grid. The CoF coordinates flexible loads of customers by using information on their planned electrical demands given by their home energy management systems. Based on the aggregated demand data, the predicted grid condition is analyzed. If congestion is detected it is resolved by making adjustments to the flexible loads from their original plans utilizing the opportunities provided by the CoF. For the energy rescheduling two different methods, i.e., a quota-based
approach and an equal-share approach, are evaluated. The results show that, by adjusting flexible loads, the CoF can effectively resolve anticipated congestion while creating only minimal curtailments for the customers. However, this will come with significant costs of up to 10% for the customers, so there is a need for compensation for participating in a flexibility coordination. The comparison of both methods shows that a hybrid approach should be pursued in further research
In situ compression of ceramic-organic supraparticles: Deformation and fracture behavior
No full textSupercrystalline nanocomposites (SCNCs) feature intriguing functionalities and exceptional mechanical properties, but they are usually confronted with challenges when it comes to processing them in larger bulk form. One way to tackle this problem is a hierarchical approach, for which spherical SCNCs, i.e. supraparticles (SPs), are promising candidates as building blocks. Understanding the mechanical behavior of SPs is thus a key step towards the development of robust, multifunctional and macroscopic SCNCs. Hereby, in situ compression tests are performed on SPs with varying sizes and levels of crosslinking of their organic ligands. A size-dependent deformation and fracture behavior emerges. Plasticity occurs in larger SPs, while small ones exhibit brittle fracture. Surface stress and compaction affect the elastic modulus. Fracture initiation sites shift from the center of SPs to their equatorial belts with the decrease of SPs’ size. The inverse scaling relationship between fracture strength and SPs’ sizes is rationalized via Griffith theory
Exploring NAS for anomaly detection in superconducting cavities of particle accelerators
No full textThe European X-Ray Free Electron Laser is the largest particle accelerator for X-ray laser generation worldwide. To ensure a safe and efficient operation, the plant uses various monitoring systems, especially in the linear accelerator. The low-level radio frequency system has shown reliability in diagnostics, particularly in quench detection. A quench refers to a superconducting radio frequency cavity losing its superconductivity and possibly causing a downtime. The diagnostics solution, however, can be enhanced in terms of robustness and functionality. Currently, the focus is on integrating artificial intelligence to improve quench identification. Thus, a lightweight machine learning-assisted approach targeting FPGA deployment is developed. It relies on the augmentation of a physical model-based anomaly detection approach with neural network models to distinguish the quenches from the other anomalies. This paper presents the solution in which neural architecture search is applied, and elaborates on how visualizing and analyzing the anomaly detection results can provide critical insights for both short-term diagnostics and long-term pattern identification