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Powder synthesis is crucial for achieving the densification and facilitating widespread applications of high entropy carbide (HEC). Specifically, the production of fine particle‐size powders is essential to enhance the densification of HECs. Consequently, this paper proposes the molten salt method for synthesizing HEC powders. The synthesis process successfully yielded (Ta Nb Ti V) C powders with a particle size of only 0.44 µm at 1400°C, exhibiting a uniform distribution of each element. Subsequent densification of (Ta Nb Ti V) C within the 1700–1900°C temperature range was carried out using spark plasma sintering. It was observed that as the densification temperature increased, the densification and mechanical properties of HEC significantly improved. This study presents innovative ideas for the preparation of HEC at lower temperatures. [ABSTRACT FROM AUTHOR]

A large adiabatic temperature change along with a wide operating temperature region is usually required for the electrocaloric materials to fulfill their refrigeration function. In general, doping foreign ions into BaTiO3 is the frequently utilized strategy in order to obtain excellent electrocaloric materials for the practical application. In the current paper, BaTiO3 lead‐free ferroelectric ceramics were doped by Ca2+ and Sn4+ simultaneously in order to generate a coexistence state at room temperature, where ferroelectric domains and nanodomains exit. As a result, a large polarization and a wide operating temperature range were finally induced. It is found that Ba0.9Ca0.1Ti0.85Sn0.15O3 has a maximum adiabatic temperature change of 0.85 K and an excellent working temperature region (65 K, ∆T > 90% Tmax) was achieved under an electric field of 50 kV/cm. The above phenomenon indicates that the modified BaTiO3 ceramics can be a good potential electrocaloric material in the state of cross‐existence of ferroelectric domains and nanodomains. [ABSTRACT FROM AUTHOR]

The full matrix parameters of a piezoelectric material are crucial for designing and evaluating piezoelectric devices. However, due to their inverse problematic nature, commonly used single‐sample characterization methods heavily depend on the accuracy of initial values and mode matching. In this paper, we propose a quasi‐31‐vibrator method to directly evaluate these parameters by designing the sample geometry and establishing the relationship equation between the parameters. This approach completely bypasses the need for characteristic spectrum simulation and mode identification processes. Subsequently, we tested the full matrix parameters of PZT‐5H ceramics and compared the simulated impedance spectra with the measured ones. The presence of well‐fitting spectra validates the feasibility of the method. This method will contribute to characterize the parameters of new piezoelectric materials and advance the intelligent implementation of measuring full matrix parameters. [ABSTRACT FROM AUTHOR]

Proton resonance frequency shift (PRFS) MR thermometry is the most common method used in clinical thermal treatments because of its fast acquisition and high sensitivity to temperature. However, motion is the biggest obstacle in PRFS MR thermometry for monitoring thermal treatment in moving organs. This challenge arises because of the introduction of phase errors into the PRFS calculation through multiple methods, such as image misregistration, susceptibility changes in the magnetic field, and intraframe motion during MRI acquisition. Various approaches for motion correction have been developed for real‐time, motion‐robust, and volumetric MR thermometry. However, current technologies have inherent trade‐offs among volume coverage, processing time, and temperature accuracy. These tradeoffs should be considered and chosen according to the thermal treatment application. In hyperthermia treatment, precise temperature measurements are of increased importance rather than the requirement for exceedingly high temporal resolution. In contrast, ablation procedures require robust temporal resolution to accurately capture a rapid temperature rise. This paper presents a comprehensive review of current cutting‐edge MRI techniques for motion‐robust MR thermometry, and recommends which techniques are better suited for each thermal treatment. We expect that this study will help discern the selection of motion‐robust MR thermometry strategies and inspire the development of motion‐robust volumetric MR thermometry for practical use in clinics. [ABSTRACT FROM AUTHOR]

Purpose: In MRI, motion artifacts can significantly degrade image quality. Motion artifact correction methods using deep neural networks usually required extensive training on large datasets, making them time‐consuming and resource‐intensive. In this paper, an unsupervised deep learning‐based motion artifact correction method for turbo‐spin echo MRI is proposed using the deep image prior framework. Theory and Methods: The proposed approach takes advantage of the high impedance to motion artifacts offered by the neural network parameterization to remove motion artifacts in MR images. The framework consists of parameterization of MR image, automatic spatial transformation, and motion simulation model. The proposed method synthesizes motion‐corrupted images from the motion‐corrected images generated by the convolutional neural network, where an optimization process minimizes the objective function between the synthesized images and the acquired images. Results: In the simulation study of 280 slices from 14 subjects, the proposed method showed a significant increase in the averaged structural similarity index measure by 0.2737 in individual coil images and by 0.4550 in the root‐sum‐of‐square images. In addition, the ablation study demonstrated the effectiveness of each proposed component in correcting motion artifacts compared to the corrected images produced by the baseline method. The experiments on real motion dataset has shown its clinical potential. Conclusion: The proposed method exhibited significant quantitative and qualitative improvements in correcting rigid and in‐plane motion artifacts in MR images acquired using turbo spin‐echo sequence. [ABSTRACT FROM AUTHOR]

Purpose: This paper proposes a novel self‐supervised learning framework that uses model reinforcement, REference‐free LAtent map eXtraction with MOdel REinforcement (RELAX‐MORE), for accelerated quantitative MRI (qMRI) reconstruction. The proposed method uses an optimization algorithm to unroll an iterative model‐based qMRI reconstruction into a deep learning framework, enabling accelerated MR parameter maps that are highly accurate and robust. Methods: Unlike conventional deep learning methods which require large amounts of training data, RELAX‐MORE is a subject‐specific method that can be trained on single‐subject data through self‐supervised learning, making it accessible and practically applicable to many qMRI studies. Using quantitative T1$$ {\mathrm{T}}_1 $$ mapping as an example, the proposed method was applied to the brain, knee and phantom data. Results: The proposed method generates high‐quality MR parameter maps that correct for image artifacts, removes noise, and recovers image features in regions of imperfect image conditions. Compared with other state‐of‐the‐art conventional and deep learning methods, RELAX‐MORE significantly improves efficiency, accuracy, robustness, and generalizability for rapid MR parameter mapping. Conclusion: This work demonstrates the feasibility of a new self‐supervised learning method for rapid MR parameter mapping, that is readily adaptable to the clinical translation of qMRI. [ABSTRACT FROM AUTHOR]

Purpose: The delay alternating with nutation for tailored excitation (DANTE)–sampling perfection with application‐optimized contrasts (SPACE) sequence facilitates 3D intracranial vessel wall imaging with simultaneous suppression of blood and CSF. However, the achieved image contrast depends closely on the selected sequence parameters, and the clinical use of the sequence is limited in vivo by observed signal variations in the vessel wall, CSF, and blood. This paper introduces a comprehensive DANTE‐SPACE simulation framework, with the aim of providing a better understanding of the underlying contrast mechanisms and facilitating improved parameter selection and contrast optimization. Methods: An extended phase graph formalism was developed for efficient spin ensemble simulation of the DANTE‐SPACE sequence. Physiological processes such as pulsatile flow velocity variation, varying flow directions, intravoxel velocity variation, diffusion, and B1+$$ {\mathrm{B}}_1^{+} $$ effects were included in the framework to represent the mechanisms behind the achieved signal levels accurately. Results: Intravoxel velocity variation improved temporal stability and robustness against small velocity changes. Time‐varying pulsatile velocity variation affected CSF simulations, introducing periods of near‐zero velocity and partial rephasing. Inclusion of diffusion effects was found to substantially reduce the CSF signal. Blood flow trajectory variations had minor effects, but B1+$$ {\mathrm{B}}_1^{+} $$ differences along the trajectory reduced DANTE efficiency in low‐B1+$$ {\mathrm{B}}_1^{+} $$ areas. Introducing low‐velocity pulsatility of both CSF and vessel wall helped explain the in vivo observed signal heterogeneity in both tissue types. Conclusion: The presented simulation framework facilitates a more comprehensive optimization of DANTE‐SPACE sequence parameters. Furthermore, the simulation framework helps to explain observed contrasts in acquired data. [ABSTRACT FROM AUTHOR]

Purpose: Recent numerical and empirical results proved that high permittivity materials (HPM) used in pads placed near the subject or directly integrated with coils can increase the SNR and reduce the specific absorption rate (SAR) in MRI. In this paper, we propose an analytical investigation of the effect on the magnetic field distribution of a layer of HPM surrounding an anatomy‐mimicking cylindrical sample. Methods: The study is based on a reformulation of the Mie scattering for cylindrical geometry, following an approach recently introduced for spherical samples. The total field in each medium is decomposed in terms of inward and outward electromagnetic waves, and the fields are expressed as series of cylindrical harmonics, whose coefficients can be interpreted as classical reflection and transmission coefficients. Results: Our new formulation allows a quantitative evaluation of the effect of the HPM layer for varying permittivity and thickness, and it provides an intuitive understanding of such effect in terms of propagation and scattering of the RF field. Conclusion: We show how HPM can filter out the modes that only contribute to the noise or RF power deposition, resulting in higher SNR or lower SAR, respectively. Our proposed framework provides physical insight on how to properly design HPM for MRI applications. [ABSTRACT FROM AUTHOR]

This paper presents our contribution to the a posteriori error analysis in 2D and 3D of a semi‐augmented mixed‐primal finite element method previously developed by us to numerically solve double‐diffusive natural convection problem in porous media. The model combines Brinkman‐Navier‐Stokes equations for velocity and pressure coupled to a vector advection‐diffusion equation, representing heat and concentration of a certain substance in a viscous fluid within a porous medium. Strain and pseudo‐stress tensors were introduced to establish scheme solvability and provide a priori error estimates using Raviart‐Thomas elements, piecewise polynomials and Lagrange finite elements. In this work, we derive two reliable residual‐based a posteriori error estimators. The first estimator leverages ellipticity properties, Helmholtz decomposition as well as Clément interpolant and Raviart‐Thomas operator properties for showing reliability; efficiency is guaranteed by inverse inequalities and localization strategies. An alternative estimator is also derived and analyzed for reliability without Helmholtz decomposition. Numerical tests are presented to confirm estimator properties and demonstrate adaptive scheme performance. [ABSTRACT FROM AUTHOR]

In this paper, a second‐order time discretizing block‐centered finite difference method is introduced to solve the compressible wormhole propagation. The optimal second‐order error estimates for the porosity, pressure, velocity, concentration and its flux are established carefully in different discrete norms on non‐uniform grids. Then by introducing Lagrange multiplier, a novel bound‐preserving scheme for concentration is constructed. Finally, numerical experiments are carried out to demonstrate the correctness of theoretical analysis and capability for simulations of compressible wormhole propagation. [ABSTRACT FROM AUTHOR]

By postprocessing quadratic and eight‐node serendipity finite element solutions on arbitrary triangular and quadrilateral meshes, we obtain new quadratic/serendipity finite volume element solutions for solving anisotropic diffusion equations. The postprocessing procedure is implemented in each element independently, and we only need to solve a 6‐by‐6 (resp. 8‐by‐8) local linear algebraic system for triangular (resp. quadrilateral) element. The novelty of this paper is that, by designing some new quadratic dual meshes, and adding six/eight special constructed element‐wise bubble functions to quadratic/serendipity finite element solutions, we prove that the postprocessed solutions satisfy local conservation property on the new dual meshes. In particular, for any full anisotropic diffusion tensor, arbitrary triangular and quadrilateral meshes, we present a general framework to prove the existence and uniqueness of new quadratic/serendipity finite volume element solutions, which is better than some existing ones. That is, the existing theoretical results are improved, especially we extend the traditional rectangular assumption to arbitrary convex quadrilateral mesh. As a byproduct, we also prove that the new solutions converge to exact solution with optimal convergence rates under H1$$ {H}^1 $$ and L2$$ {L}^2 $$ norms on primal arbitrary triangular/quasi–parallelogram meshes. Finally, several numerical examples are carried out to validate the theoretical findings. [ABSTRACT FROM AUTHOR]

The random greedy algorithm for finding a maximal independent set in a graph constructs a maximal independent set by inspecting the graph's vertices in a random order, adding the current vertex to the independent set if it is not adjacent to any previously added vertex. In this paper, we present a general framework for computing the asymptotic density of the random greedy independent set for sequences of (possibly random) graphs by employing a notion of local convergence. We use this framework to give straightforward proofs for results on previously studied families of graphs, like paths and binomial random graphs, and to study new ones, like random trees and sparse random planar graphs. We conclude by analysing the random greedy algorithm more closely when the base graph is a tree. [ABSTRACT FROM AUTHOR]

This paper presents a general variational principle as theoretical support for creating a simple and efficient quadrilateral plate finite element called BKWA, having only a single displacement and two rotations at corner nodes according to the Reissner‐Mindlin plate theory. The functional is a modified Hellinger‐Reissner in terms of the kinematic variables and independent transverse shear strains. Hence, we consider quadratic rotations, as in DKQ, and linear independent shear strains with constant tangential components on sides, as in MITC4. The quadratic rotation contributions and the mixed shear strain components are wiped out by static condensation. To adequately satisfy the constant curvature patch tests, we also consider the orthogonality conditions between the linear and quadratic bending modes, as in the Bergan free formulation, to avoid 'spurious bending energy' for thick plates (also called bending locking). The paper contains comprehensive patch tests and convergence tests with regular and irregular meshes (displacements, internal forces, and strain energy) of circular and square plates. The element is compared with other existing elements (MITC4, DKMQ). It is concluded that BKWA is an efficient element regarding several criteria. [ABSTRACT FROM AUTHOR]

Thanks to recent developments in hardware and software, quantum chemical methods are increasingly used for interpreting the complex mechanisms underlying polymerization reaction by homogeneous catalysis. Unfortunately, the dimensions of even the smallest realistic models are too large to permit the use of state‐of‐the‐art composite wave function methods. Under these circumstances, density functional theory still offers the best compromise between cost and accuracy. However, comprehensive benchmarks of different functionals are not yet available for this important research field. The main aim of the present paper is to fill this gap by performing an unbiased comparison of several density functionals and continuum solvent models for the stereo‐control in the propylene polymerization on prototypical catalysts inducing different reaction mechanisms. While it was not possible to define a unique computational protocol providing the best results in all the situations, the B3PW91 functional in conjunction with D3 empirical dispersions and the solvent model density solvent model performs remarkably well for three out of the four investigated catalysts. Under such circumstances, it is recommended to compare the results delivered by different models when approaching additional classes of catalysts. [ABSTRACT FROM AUTHOR]

Rationale: Atmospheric pressure matrix‐assisted laser desorption/ionization (AP‐MALDI) mass spectrometry has enabled the untargeted analysis and imaging of neuropeptides and proteins in biological tissues under ambient conditions. Sensitivity in AP‐MALDI can be improved by using sample‐specific preparation methods. Methods: A comprehensive and detailed optimization strategy including instrument parameters, matrix spraying and sample tissue washing pretreatment was implemented to enhance the sensitivity and coverage of neuropeptides in mouse pituitary tissues by commercial AP‐MALDI mass spectrometry imaging (MSI). Results: The sensitivity of a commercial AP‐MALDI system for endogenous neuropeptides in mouse pituitary was enhanced by up to 15.2‐fold by shortening the transmission gap from the sample plate to the inlet, attaching copper adhesive tape to an indium tin oxide‐coated glass slide, optimizing the matrix spray solvent and using sample tissue washing pretreatment. Following careful optimization, the distributions of nine endogenous neuropeptides were successfully visualized in the pituitary. Furthermore, the quantitative capability of AP‐MALDI for neuropeptides was evaluated and the concentrations of neuropeptides oxytocin and vasopressin in the pituitary posterior lobe were increased approximately twofold under hypertonic saline stress. Conclusion: Mouse pituitary neuropeptides have emerged as important signaling molecules due to their role in stress response. This work indicates the potential of modified AP‐MALDI as a promising AP MSI method for in situ visualization and quantification of neuropeptides in complex biological tissues. [ABSTRACT FROM AUTHOR]

Summary: The distributed and decentralized architecture of cloud computing is important for a number of industries, including business, government, entertainment, education, and information technology. It facilitates a wide aspect of information technology, where the computing model is vulnerable to attacks or intrusion. For detecting malicious activities, a novel intrusion detection system (IDS) is required to be developed. In this paper, an enhanced synthetic minority oversampling technique (SMOTE) with a hybrid one‐dimensional residual auto encoder and the Ensemble of Gradient Boosting (1D‐RAE‐EGB) models are proposed for cloud intrusion detection. The proposed IDS resolves the class imbalance problem through enhanced SMOTE. In addition, noise reduction is accomplished with ID‐RAE, which minimizes the data dimension. Finally, the soft voting‐based ensemble classification model is used for attack detection. The ensemble gradient boosting model comprises categorical boosting (CatBoost), extreme gradient boosting (XGBoost), and light gradient boosting machine (LightGBM). The ensemble model is fine‐tuned by reducing the number of parameters under fitting conditions since it is not compulsory to re‐adjust the weight values in a backpropagation process. The proposed IDS is implemented in Python using the NSL‐KDD dataset. The accuracy, precision, recall, f1‐score, false positive rate (FPR), false negative rate (FNR), specificity, and Kappa measure obtained for the proposed IDS are 99.98%, 99.3%, 98.5%, 99.95%, 0.723, 0.46, 99.98%, and 99.97%, respectively. [ABSTRACT FROM AUTHOR]

Summary: Metaheuristic algorithms have special effects in solving optimization problems in real life and have become the focus of researchers. The sparrow search algorithm (SSA) is a newly proposed swarm‐based metaheuristic algorithm that has shown excellent optimization performance. Although compared with other algorithms, SSA shows good performance, the original SSA algorithm still has problems such as weak optimization ability, leading to falling into the local optimum, and being unable to balance exploration and exploitation well. Therefore, this paper proposes an improved SSA using chaotic opposition‐based learning and hybrid updating rules (CHSSA). First, chaotic opposition‐based learning is proposed to improve the diversity of the population. Second, two strategies, including adaptive weights and spiral search, are adopted to update the position. Finally, to evaluate the performance of the proposed CHSSA, this paper uses 23 benchmark functions, IEEE CEC 2017 functions and 4 practical engineering optimization problems to evaluate the algorithm performance. The experimental results show that compared with other advanced optimization algorithms, CHSSA has the characteristics of fast convergence speed, high search accuracy, and strong robustness. [ABSTRACT FROM AUTHOR]

Summary: In this paper, the governing equations of the outrigger‐braced structure are formulated by considering the influence of core‐wall width. The axial forces in the columns are considered as unknowns and the compatibility of the column's axial deformation is considered in formulating the governing equations. Then, the governing equations for the optimum locations of outriggers are formulated by minimizing the top drift of central core wall. After that, the influence of core‐wall width on the optimum outrigger locations, the drift‐reduction efficiency and moment‐reduction efficiency is investigated numerically. Some results are presented for the reference in the preliminary design of the outrigger‐braced structures. [ABSTRACT FROM AUTHOR]

Summary: In operational modal analysis (OMA), only structural responses are typically available. In this context, bias and variance (uncertainty) errors may exist in modal estimates (especially damping estimates), resulting in inaccurate determination of the modal properties of large‐scale structures under harsh excitations. To this end, a hybrid OMA framework based on the modal decoupling, the natural excitation technique, the random decrement technique (RDT), and improved eigensystem realization algorithm (ERA) with the automated stabilization diagram is presented to perform high‐accuracy modal estimates with uncertainty quantification for large‐scale structures under normal and severe ambient excitations. The accuracy and effectiveness of the hybrid framework for identifying the modal parameters are validated by numerical simulation study of a framework structural model. Furthermore, the hybrid framework is applied to analyze recorded acceleration responses of a supertall building with 600‐m height under normal excitations and typhoon condition to verify its applicability in field measurements. The numerical simulation and field measurement studies demonstrate that the hybrid framework can not only perform precise modal estimations with uncertainty quantification through a single ambient vibration measurement but also effectively reveal the variations of modal properties of supertall structures under harsh excitations from multiple perspectives. This paper aims to enhance the reliability and accuracy of modal estimation for engineering structures and further provide insight into the variations of dynamic properties of large‐scale civil structures under severe excitations. [ABSTRACT FROM AUTHOR]

Summary: This research deals with a frame‐supported shear wall for urban over‐track building of vehicle depot in Chisha, Guangzhou, China, which is characterized by its remarkable height of 160.8 m. Technical issues are commonly encountered in these kinds of buildings due to discontinuous vertical structural rigidity, large podium, and structural transition. These challenges significantly impact the engineering process, especially when the rigidity difference between transfer story exceeding the threefold, as well as the building height exceeds limit as in code. In this paper, a shaking table test was developed based on a 1:10 scaled model of the structure. Using similarity theory, the dynamic similarity relationship was established for the design of the model. Subsequently, the experimental model was constructed with the configuration of critical parameters such as mass design, sensor placement, and seismic test conditions. This was followed by in‐depth analysis, recording component failures and investigating key aspects such as dynamic characteristics, that is, acceleration and displacement responses and shear force distribution under different earthquake intensities. A theoretical seismic response of the prototype structure was derived from the test results. The shaking table tests confirmed that the structure met the stringent seismic design requirements as prescribed in the Chinese standards, with no damage under minor earthquakes, repairability under moderate earthquakes, and collapse prevention under rare earthquakes. The results of the study provide valuable insights along with improvement measures for the design and development of similar urban over‐track buildings, potentially contributing to more efficient land use in urban China. [ABSTRACT FROM AUTHOR]