Stryhnho3438

Carbon fiber reinforced polymers (CFRPs) are composite materials in which carbon provides strength and stiffness, whereas polymers provide cohesiveness and toughness. The electrical impedance of CFRP laminates is changed due to different kinds of damages. Electrical impedance tomography (EIT) has significant advantages such as non-intrusion, portability, low cost, and quick response and has widely been used as a nondestructive testing method. Therefore, EIT has great potential in structural health monitoring of CFRPs. Regularization can solve the ill-posed inverse problem of EIT. However, conventional regularization algorithms have their own limitations, such as over-smoothness of reconstructed edges and unstable solution caused by measurement noise. In addition, the anisotropic property of CFRPs also affects the image quality based on traditional methods. In this paper, the sorted L1-norm regularization is proposed. It promotes grouping highly correlated variables while encouraging sparsity by using more effective penalty terms. The sharp edges between different materials can be obtained, and the obtained solution is more stable. The image quality of different objects, especially the image quality of multi-targets, can be significantly improved with this new method. In addition, the sorted L1 norm can generate adaptive regularization parameters without empirical selection. The new regularization problem is solved by the alternating direction method of multipliers. Both experimental and simulation results demonstrate that the sorted L1 norm improves the quality of reconstructed images under various noise levels. The proposed method is comprehensively evaluated with three image quality criteria by numerical simulation quantitatively.This paper proposed a three-core fiber Bragg grating (FBG) probe for sub-millinewton contact force measurement of a micromanipulator system. The probe comprises a bundle of three single-core FBGs assembled under the effect of capillary self-assembly. Theoretical relationships between Bragg wavelength and force are calculated based on the assumption of material mechanics. The experimental results show that the probe has a good linear relationship for the measurement of the radial two degrees of freedom contact force, and it is suitable for measuring the radial contact force of 0.1-1 mN. The proposed three-core FBG probe has the characteristics of simple structure, low cost, and better forming stability and sensitivity compared with the four-core structure.A novel double full-cylinder crystal x-ray spectrometer for x-ray emission spectroscopy (XES) has been realized based on a modified von Hamos geometry. The spectrometer is characterized by its compact dimensions, its versatility with respect to the number of crystals used in series in the detection path, and the option to perform calibrated XES measurements. The full-cylinder crystals used are based on highly annealed pyrolytic graphite with a thickness of 40 μm, which was bent to a radius of curvature of 50 mm. The flexible design of the spectrometer allows for an easy change-within the same setup-between measurements with one crystal for maximized efficiency or two crystals for increased spectral resolving power. The spectrometer realized can be used at different end-stations of synchrotron radiation beamlines or can be laboratory-based. selleckchem The main application focus of the spectrometer is the determination of x-ray fundamental atomic parameters in the photon energy range from 2.4 to 18 keV. The evaluation of chemical speciation is also an area of application, as demonstrated in the example of battery electrodes using resonant inelastic x-ray scattering.Hot cathode discharges are common plasma sources for fundamental plasma physics studies and other applications due to their quiescent and relatively simple properties, and tungsten filaments are commonly used for the ease of heating them. Recently, tungsten filaments are increasingly being replaced by less luminous alternatives, such as barium oxide or lanthanum hexaboride. These materials can emit electrons at temperatures close to 1000 K lower than tungsten, greatly reducing their blackbody radiations. This results in significant improvement in signal recovery for active spectral diagnostic, such as laser-induced fluorescence. However, these less luminous cathodes often come in vastly more complicated designs than those of tungsten hot cathodes and are much more expensive to procure and difficult to operate. In this paper, we present a simple, low cost direct current heated design of a LaB6 cathode that is manufactured at suitable dimensions and make a comparison of the laser-induced fluorescence (LIF) signal-to-noise ratio of this LaB6 hot cathode discharge with that of a typical tungsten filament discharge, revealing that LaB6 has, indeed, an improved LIF signal-to-noise ratio compared with the tungsten filament.Radio frequency vacuum electronics are prone to multipactor discharges. These electron discharges, driven by secondary electron emission, can disrupt and damage devices and are particularly important in satellite communication systems. We present results from a new S-band coaxial multipactor test cell which demonstrates scaling to much higher frequencies (3.05 GHz) than previous coaxial experiments (10-150 MHz). The multipactor breakdown threshold has been found to agree very well with our earlier simulated predictions. The significant effect from multipactor self-conditioning has also been demonstrated and characterized. Future experiments will use this test cell to investigate various multipactor mitigation strategies.An efficient cryogenic distillation system was designed and constructed for the PandaX-4T dark matter detector based on the McCabe-Thiele method and the conservation of mass and energy. This distillation system is designed to reduce the concentration of krypton in commercial xenon from 5 × 10-7 to ∼10-14 mol/mol with 99% xenon collection efficiency at a maximum flow rate of 10 kg/h. The offline distillation operation has been completed and 5.75 tons of ultra-high purity xenon was produced, which is used as the detection medium in the PandaX-4T detector. The krypton concentration of the product xenon is measured with an upper limit of 8.0 ppt. The construction, operation, and stable purification performance of the cryogenic distillation system are studied with the experimental data, which is important for theoretical research and distillation operation optimization.Stochastic configuration networks (SCNs) employ a supervisory mechanism to assign hidden-node parameters in the incremental construction process. SCNs offer the advantages of practical implementation, fast convergence, and better generalization performance. However, due to its high computational cost and the scalability of numerical algorithms for the least square technique, it is rather limited for dealing with enormous amounts of data. This paper proposes fast SCNs (F-SCNs), whose output weights are determined using orthogonal matrix Q and upper triangular matrix R decomposition. The network can iteratively update the output weights utilizing the output information from the predecessor node using this incremental technique. We investigated the computational complexity of SCNs and F-SCNs and demonstrated that F-SCNs are suitable for scenarios in which the hidden layer has a significant number of nodes. We evaluated the proposed method on four real-world regression datasets; experimental results show that our method has notable advantages in terms of speed and effectiveness of learning.We report a theoretical framework for weak polyelectrolytes by combining the polymer density functional theory with the Ising model for charge regulation. The so-called Ising density functional theory provides an accurate description of the effects of polymer conformation on the ionization of individual segments and is able to account for both the intra- and interchain correlations due to the excluded-volume effects, chain connectivity, and electrostatic interactions. Theoretical predictions of the titration behavior and microscopic structure of ionizable polymers are found to be in excellent agreement with the experiment.Unraveling the atomistic and the electronic structure of solid-liquid interfaces is the key to the design of new materials for many important applications, from heterogeneous catalysis to battery technology. Density functional theory (DFT) calculations can, in principle, provide a reliable description of such interfaces, but the high computational costs severely restrict the accessible time and length scales. Here, we report machine learning-driven simulations of various interfaces between water and lithium manganese oxide (LixMn2O4), an important electrode material in lithium ion batteries and a catalyst for the oxygen evolution reaction. We employ a high-dimensional neural network potential to compute the energies and forces several orders of magnitude faster than DFT without loss in accuracy. In addition, a high-dimensional neural network for spin prediction is utilized to analyze the electronic structure of the manganese ions. Combining these methods, a series of interfaces is investigated by large-scale molecular dynamics. The simulations allow us to gain insights into a variety of properties, such as the dissociation of water molecules, proton transfer processes, and hydrogen bonds, as well as the geometric and electronic structure of the solid surfaces, including the manganese oxidation state distribution, Jahn-Teller distortions, and electron hopping.The superposition of the frequency dispersions of the structural α relaxation determined at different combinations of temperature T and pressure P while maintaining its relaxation time τα(T, P) constant (i.e., isochronal superpositioning) has been well established in molecular and polymeric glass-formers. Not known is whether the frequency dispersion or time dependence of the faster processes including the caged molecule dynamics and the Johari-Goldstein (JG) β relaxation possesses the same property. Experimental investigation of this issue is hindered by the lack of an instrument that can cover all three processes. Herein, we report the results from the study of the problem utilizing molecular dynamics simulations of two different glass-forming metallic alloys. The mean square displacement 〈Δr2t〉, the non-Gaussian parameter α2t, and the self-intermediate scattering function Fsq,t at various combinations of T and P were obtained over broad time range covering the three processes. Isochronal superpositioning of 〈Δr2t〉, α2t, and Fsq,t was observed over the entire time range, verifying that the property holds not only for the α relaxation but also for the caged dynamics and the JG β relaxation. Moreover, we successfully performed density ρ scaling of the time τα2,maxT,P at the peak of α2t and the diffusion coefficient D(T, P) to show both are functions of ργ/T with the same γ. It follows that the JG β relaxation time τβ(T, P) is also a function of ργ/T since τα2,maxT,P corresponds to τβ(T, P).Molecular Dynamics (MD) simulations of proteins implicitly contain the information connecting the atomistic molecular structure and proteins' biologically relevant motion, where large-scale fluctuations are deemed to guide folding and function. In the complex multiscale processes described by MD trajectories, it is difficult to identify, separate, and study those large-scale fluctuations. This problem can be formulated as the need to identify a small number of collective variables that guide the slow kinetic processes. The most promising method among the ones used to study the slow leading processes in proteins' dynamics is the time-structure based on time-lagged independent component analysis (tICA), which identifies the dominant components in a noisy signal. Recently, we developed an anisotropic Langevin approach for the dynamics of proteins, called the anisotropic Langevin Equation for Protein Dynamics or LE4PD-XYZ. This approach partitions the protein's MD dynamics into mostly uncorrelated, wavelength-dependent, diffusive modes.