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High ductility geopolymer (HDG) looks promising as an exceptional repair material due to the faultless mechanical properties and environmental benefits. The interfacial bonding characteristics between existing normal concrete (NC) substrate and HDG overlay are the vital impact on the overall performance of repaired structures. This study presented the NC-HDG bonding behavior under the direct shear tests, and totally 45 specimens were designed with various concrete strength grades, interface roughness and elongations of HDG. To capture the fracture characteristics, the digital image correlation (DIC) technique was employed. Test results showed that the direct shear bonding strength (τ u) had an increasing trend as the NC strength dropped or the interface roughness and elongations of HDG were increased, among the interface roughness affected the τ u mostly, with the improvement amount of 185.07 %∼343.28 %. The direct shear strength ratio (defined as the ratio of τ u to the inherent shear strength of NC) was ranged as 0.110∼0.489, i.e., at least half of shear strength of NC was lost during repairing. Based on the DIC measured results, the improvement of NC strength, interface roughness and elongations of HDG all delayed the interfacial crack initiation under direct shear loading. Moreover, the upper-bound limit analysis was adopted, a simplified method for predicting the direct shear bonding strength of NC-HDG interface was proposed and showed a sufficient precision. • 45 NC-HDG bonded specimen are conducted under direct shear test. • Interface roughness affected the τ u mostly. • At least half of shear strength of NC was lost during repairing. • A method for predicting the bonding strength was proposed. [ABSTRACT FROM AUTHOR]

This study presents an experimental investigation aim at evaluating the slenderness effects on concrete-filled square steel tube columns strengthened with a carbon fiber-reinforced polymer (CFRP) grid-reinforced engineered cementitious composite matrix. Thirteen columns were subjected to axial compression, with the studied parameters including the length-to-width (L / B) ratio, CFRP grid layer number, concrete strength grade, and width-to-thickness ratio of the steel tube. Test results revealed that slender columns experienced an increase in load-bearing capacity ranging from 27.1 % to 32.4 % after strengthening, while the ductility enhancement reached a peak of 52.0 %. A column with an L / B ratio of 5.87 exhibited slight bending deformation in a localized region upon failed, with CFRP grid ruptured at the corner. While columns with L / B ratios of 7.83 and 9.78 failed due to the loss of stability, displaying overall bending deformation. The increase in L / B ratio accelerated the loss of stability, resulting in a decrease in the ultimate load. As the L / B ratio increased from 2.97 to 5.93, 7.91 and 9.89, the ultimate loads of the strengthened columns decreased by 7.4 %, 9.2 %, and 15.4 %, respectively. A load-bearing capacity calculation model of slender strengthened columns was developed using the fiber element method. Through numerical analysis, a stability coefficient was introduced, and a simplified calculation formula was proposed to predict the stability bearing capacity. • Slender square CFST columns were strengthened using CFRP grid-reinforced ECC. • Slenderness effects on the strengthened columns were evaluated. • A model and a simplified formula were proposed to predict the bearing capacity. [ABSTRACT FROM AUTHOR]

In this study, a bidirectional fluid-structure interaction (FSI) method was proposed based on dynamic mesh technology to calculate the erosion defects of pipe bends under high pressure. In calculating the erosion rate of pipe bends, a stress erosion model was adopted, and the displacement and stress of the inner wall of pipe bend under high external pressure were considered. The influence of different parameters on the calculation results of erosion depth was discussed, and the buckling pressure and collapse mode of pipe bend under the erosion defect of liquid-solid flow were also studied. The proposed method can be used for predicting pipeline erosion defects under high pressure and evaluating the remaining limit load of pipelines with such erosion defects. • A bidirectional fluid structure interaction method was proposed to calculate the erosion of pipe bend under high pressure. • The deformation and stress of pipe bend under high pressure were considered in the fluid domain calculation. • A displacement field transfer method was proposed to update the solid mesh automatically based on erosion results. • The influence of erosion defects on pipe bend buckling was analyzed on the basis of erosion analysis. [ABSTRACT FROM AUTHOR]

• Utilizes text mining to identify blockchain-as-a-service (BaaS) providers. • Uncovers vulnerabilities in the internal control mechanisms of BaaS providers. • Identifies higher risks of financial restatements and cybersecurity breaches in BaaS providers. • Highlights BaaS providers seeking assistance from high-quality auditors to address challenges. • Emphasizes the necessity for regulatory guidance in the BaaS industry. This paper examines the effectiveness of the internal control mechanisms of blockchain-as-a-service (BaaS) providers. Given the lack of classification in the blockchain industry, we conduct text mining of official filings to identify BaaS providers and compare their internal control issues with those of matched firms in other industries. Our findings, which offer pivotal insights for policymakers and regulators, reveal that BaaS providers are 9.6 % more susceptible to internal control weaknesses compared to firms in other industries. This susceptibility results in an increased probability of financial restatements (3.4 %) and cybersecurity breaches (0.5 %). Furthermore, we show that BaaS providers invest 2.078 times more in audit services to address their internal control weaknesses. However, regulatory bodies have yet to prioritize internal control weaknesses in BaaS providers. [ABSTRACT FROM AUTHOR]

Accurate cluster photovoltaic power prediction (CPPP) is crucial for the operation and control of renewable energy grid-connected power systems. The traditional modeling strategies for CPPP such as direct aggregation (DA) and statistical upscaling (SU) have limitations such as error accumulation and upscaling factor uncertainty. To address these issues, this paper proposed a novel hybrid approach for CPPP by combining machine learning models with an improved SU technique. Firstly, a robust broad learning system (BLS) model, in which the Generalized Maximum Correntropy Criterion (GMCC) is used to replace the original mean square error (MSE) loss in BLS, is proposed to solve the problem of multiple outliers affecting the prediction accuracy of regional cluster stations, and it is called GBLS. Then, the Relevance Vector Machine (RVM) as an effective nonlinear regression model is further utilized to compensate for the prediction errors obtained by the GBLS to form the hybrid prediction model, namely GBLS-RVM. Moreover, to mitigate the uncertainty associated with scaling factors in traditional SU strategy, a new SU strategy is developed to refine the relationship between the reference station and the cluster sub-region, enabling direct modeling for regional power prediction. Finally, data from two PV clusters in different regions of China are used to validate the effectiveness of the proposed model, and the results show that under the improved SU strategy, the GBLS-RVM model, reduced RMSE by approximately 33.7% compared to the traditional BLS model, and the RMSE decreased by 12.89% and 30.2% when compared to traditional DA and traditional SU strategies. • A novel hybrid method for CPPP is developed by combining ML and improved SU technique. • A BLS with GMCC (GMCC-BLS) as a prediction model is developed to handle the outliers in measurement data. • An innovative error correction strategy based on RVM is proposed to improve prediction reliability. • A new SU technique is used to establish direct relationships between reference stations and subregions. [ABSTRACT FROM AUTHOR]

Highly-branched cyclic dextrin (HBCD) is a novel dextrin with promising applications in functional foods. In this study, the influence of HBCD on physiochemical properties of κ-carrageenan (KC) gels was determined by rheological measurements, thermal analysis, spectral analysis, micromorphology observation, and freeze-thaw cycle test. The results revealed that the addition of HBCD at a concentration of 2% (w/v) significantly enhanced the storage modulus and freeze-thaw stability of KC gels. During the gelation, HBCD prompted the uniform distribution of KC chains and facilitated the aggregation of KC helixes to form a compact network, enhancing the mechanical properties of KC gels. Meanwhile, the small pores within the compact network contributed to reduced water loss from the KC gels. Comparatively, the syneresis of KC gels with 2% HBCD was 19.80% after the first freeze-thaw cycle and 46.51% after complete cycles (five times), much lower than that observed in pure KC gels (66.50% after the first cycle and 68.15% after the fifth cycle). Furthermore, the attachment of HBCD to the network wall strengthened hydrogen-bonding interactions, thereby enhancing the thermal reversibility of KC gels. Overall, this research provides valuable insights and a theoretical foundation for the potential applications of HBCD in KC gels. [Display omitted] • HBCD was originally applied in KC gels. • HBCD ameliorated the mechanical properties of KC gels. • The freeze-thaw stability of KC gels was significantly perfected by HBCD. [ABSTRACT FROM AUTHOR]

• A novel two-level nesting smoothed meshfree method (NSMM) is proposed. • The NSMM is applied for structural dynamic analysis. • The NSMM is directly extended to solving dynamic fracture problems. • The NSMM is efficient, accurate and stable. This paper presents a novel two-level nesting smoothed meshfree method (NSMM), which significantly improves the computational efficiency of the meshfree Galerkin methods without losing their accuracy, thus facilitates the employment of meshfree methods in applications where background integration cells would be prohibitively expensive. In the NSMM, the system stiffness matrix is calculated using the general smoothing strain technique over the two-level nesting smoothing sub-domains where fewer integration points are used and the costly derivative computation of meshfree shape functions is avoided. The accuracy, efficiency and stability of the present method are assessed by virtue of several numerical examples for problems involving free and forced vibration analysis of the linear elastic continua and dynamic crack response of elastic solid. The results reveal that the NSMM stands out and achieves better performance compared to other existing approaches in the literature. [ABSTRACT FROM AUTHOR]

Background: Left bundle branch area pacing (LBBAP), a new pacing approach, lacks adequate evaluation.Objective: To assess the feasibility, safety, and acute effect of permanent LBBAP in patients with atrioventricular block (AVB).Methods: A total of 33 AVB patients with indications for ventricular pacing were recruited. Electrocardiograms, pacing parameters, echocardiographic measurements, and complications associated with LBBAP were evaluated perioperatively and at 3-month follow-up. Successful LBBAP was defined as a paced QRS morphology of right bundle branch block pattern in lead V1 and QRS duration (QRSd) less than 130 ms.Results: LBBAP was successfully performed in 90.9% (30/33) of patients (mean age: 55.1 ± 18.5 years; 66.7% male). The mean capture threshold was similar during the procedure (0.76 ± 0.26 V at 0.4 ms) and at the 3-month follow-up (0.64 ± 0.20 V at 0.4 ms). The paced QRSd was 112.8 ± 10.9 ms during the procedure and 116.8 ± 10.4 ms at the 3-month follow-up. Baseline left or right bundle branch block was corrected (intrinsic QRSd 153.3 ± 27.8 ms vs paced QRSd 122.2 ± 9.9 ms) with a success rate of 68.7% (11/16). One ventricular septal lead perforation occurred soon after the procedure with characteristics of pacing failure, and lead revision was successful. Cardiac function and left ventricular synchronization by 2-dimensional echocardiographic strain imaging at the 3-month follow-up slightly improved compared with that at baseline.Conclusions: Permanent LBBAP yielded a stable threshold, a narrow QRSd, and preserved left ventricular synchrony with few complications. Our preliminary results indicate that LBBAP holds promise as an attractive physiological pacing strategy for AVB. [ABSTRACT FROM AUTHOR]

Accurate estimation of the state of health (SOH) is crucial for the safe and stable operation of lithium-ion batteries. However, since the labeled values may contain non-Gaussian noise which may lead to a decrease in the effectiveness of traditional data-driven based estimation methods. Therefore, a novel robust stacking integrated learning model (ILM) is proposed to enable accurate SOH estimation under non-Gaussian noises (or outliers) conditions. The mixture correntropy loss (MCL) is used in original extreme learning machine (ELM) and the gated recurrent unit (GRU) frameworks to develop novel robust learning models, i.e MCL-ELM and MCL-GRU, and they are used as the sub-models of the proposed ILM, which takes into account the generalization performance of the model and the overall trend of SOH over the time series. In addition, the entropy weighting method that can well reflect the differences between the sub-models is utilized to reduce the complexity of the stacked ILM. Furthermore, the local tangent space alignment is used to capture the local relationships between different loops to enhance the effectiveness of the extracted health features. Several numerical experiments are performed under different cases to validate the estimation effect of the proposed model by using two publicly available datasets, and the experimental results demonstrate that the maximum RMSE, MAE, and MAPE values of the proposed model are 1.391%, 0.932%, and 1.480%, respectively, under non-Gaussian noises conditions. • Robust ELM and GRU models using MCL are developed. • Novel robust stacking ILM via the combination of the MCL-ELM and MCL-GRU is proposed for SOH estimation. • The EWM is used to obtain the output results of multiple base learners in the proposed ILM. [ABSTRACT FROM AUTHOR]

The inconsistency between good mechanical properties and rapid disintegration characteristic is a challenge for starch-based orally disintegrating films (ODF). In order to improve the mechanical and disintegration performances of the films, chitosan/pre-gelatinized waxy corn starch (PWCS) ODF was fabricated and investigated for physical properties, surface micromorphology and crystallinity. The results showed that the mechanical properties of the composite films were improved (6.55 MPa ± 1.22 MPa, 18.11% ± 2.34%) while the fast disintegration characteristic (<30 s) was still maintained. During the film-forming process, the retrogradation of PWCS chains was hindered by chitosan molecules and the polar groups were exposed, enhancing the plasticity and hydrophilicity of the composite films. There was a synergistic effect between chitosan and PWCS. In addition, the microscopic images indicated that the high compatibility of chitosan and PWCS caused a homogeneous surface for the composite films. However, PWCS aggregated when the concentration of chitosan exceeded 20%, which increased the short-range order and crystallinity of PWCS in the composite films. The study provided a theoretical feasibility for the development of novel oral carrier platform. [Display omitted] • The interaction of linear chitosan in clustered PWCS based ODF was investigated. • There was a synergistic effect between chitosan and PWCS in the ODF. • PWCS aggregated when the concentration of chitosan exceeded 20%. [ABSTRACT FROM AUTHOR]

Increasing the carotenoid content of nectarine (Prunus persica var. nucipersica) is of great significance for improving its quality and economic value. A two years study was carried out on 'Shuguang' nectarine to evaluate the effect of calcium chloride (Cl–Ca) and L-aspartic acid nano calcium [Ca (L-asp) - NPs] (nano-Ca) on carotenoid accumulation. The results show that both Cl–Ca and nano-Ca could increase the carotenoid content of nectarine fruit flesh, but the effect of nano-Ca was more significant. Nano-Ca is more easily absorbed by nectarine leaves and fruits, which improves the calmodulin activity of leaves, peel and flesh, and up-regulates the expression of carotenoid synthesis-related genes PpPSY , PpPDS , PpZDS , PpLCY-B , PpCHY-B and PpZEP. Nano-Ca also significantly up-regulated the expression of sucrose synthesis related genes PpSUS1 and PpSUS3 in leaves and sucrose transport related genes PpSUT2 and PpSUT4 in stem phloem, promoting the transport of more photosynthetic products to fruits, providing raw materials for carotenoid synthesis, and increasing the content of total sugars and ascorbic acid (Vc). In addition, nano-Ca can also up-regulate the expression levels of PpMYB10.1 and PpUFGT and promote total anthocyanins accumulation in peel. The results of our study will be useful for clarifying how nano-fertilizer improve the fruit quality of nectarine. • Nano-Ca treatment increase the calmodulin activities. • Nano-Ca up-regulates the expression levels of carotenoid biosynthesis-related genes. • Nano-Ca up-regulates the expression levels of anthocyanin biosynthesis-related genes. • Nano-Ca up-regulates the expression levels of PpSUS1 , PpSUS3 , PpSUT2 and PpSUT4. [ABSTRACT FROM AUTHOR]

Highlights • Greatly improving the efficiency of the meshfree method by transforming background cell integral into boundary integration. • Directly imposing the boundary condition without any effort. • Completely avoiding the derivation of meshfree shape functions. • Improving the accuracy of the stress field in the vicinity of the crack tips. Abstract A smoothed enriched meshfree Galerkin method with two-level nesting triangular sub-domains (NSEMM) is presented for linear elastic fracture mechanics. In the present method, displacement fields are constructed by using the linear MLS approximation in linear region away from the crack tip and the enriched MLS approximation in enriched region around the crack tip respectively. To overcome the discontinuous problem of the coupling approximations and accelerate meshfree computations, two-level nesting triangular sub-domains based on the triangular background integration cells are designed and used to construct the smoothing strain. Each two-level nesting sub-domains includes the triangular background cell itself and four equal-area triangular sub-cells. The discretized system equations are created by the Generalized smoothed Galerkin (GS-Garlerkin) weak form and Richardson extrapolation method. The values of SIFs are evaluated by using the domain form of interaction integral. Numerical examples have been simulated to demonstrate the effectiveness and robustness of the present method for crack problems with complicated configurations, and very satisfactory results have been obtained. The NSEMM takes advantages of both EFGM and generalized strain smoothing technique such as lower computational cost, high accurate and easy to implementation. [ABSTRACT FROM AUTHOR]

Previous theoretical and computational studies on hypervelocity impact have mainly focused on the dynamic response of the solid materials that constitute the projectile and the target, while the surrounding environment is often assumed to be a vacuum. In this paper, we consider impact events that occur in a fluid (e.g., gas) medium, and present a computational model that includes the dynamics, thermodynamics, and ionization of the surrounding fluid material. The model couples the compressible Navier–Stokes equations with the Saha equations to predict the onset and extent of ionization in the surrounding fluid. An extended level set method with two signed distance functions is employed to track the three material interfaces between the projectile, the target, and the ambient fluid. This method accommodates the large deformation, contact, and separation of the interfaces, while avoiding spurious overlapping of different material subdomains. The advective fluxes across material interfaces are computed by constructing and solving bimaterial Riemann problems, thereby taking into account the discontinuities in both state variables (e.g., density) and thermodynamic relations. The computational model is first verified for an infinite ideal plasma and a one-dimensional three-material impact problem. Next, the model is employed to analyze the impact of a tantalum rod projectile onto a soda lime glass (SLG) target in an argon gas environment. In different analyses, the impact velocity is varied between 3 and 6 km / s , and the radius of the projectile is varied between 2.5 and 10 mm. Each analysis starts with a steady-state fluid dynamics simulation that generates the shock-dominated hypersonic flow around the projectile. This flow field is then used as an initial condition to start the fluid–solid coupled impact simulation. The predicted maximum temperature and pressure within the SLG target agree reasonably well with published experimental data for a similar material (fused quartz). Within the ambient gas, the impact-generated shock wave is found to be stronger than the initial bow shock in front of the projectile. Behind this shock wave, a region of high pressure and temperature forms in the early stage of the impact, mainly due to the hypersonic compression of the fluid between the projectile and the target. The temperature within this region is significantly higher than the peak temperature in the solid materials. For impact velocities higher than 4 km / s , ionization is predicted. This finding indicates that the ambient gas may be a nontrivial contributor to the plasma formed in terrestrial and atmospheric hypervelocity impact events. • A fluid–solid coupled computational model of hypervelocity impact. • Three material interfaces tracked implicitly by solving two level set equations. • Ionization in the surrounding fluid predicted by the Saha equations. • Impact simulations for tantalum – soda lime glass – argon gas, 3–6 km/s. • Significant ionization detected for impact velocities higher than 4 km/s. [ABSTRACT FROM AUTHOR]

In this paper, we present a multiple-scale higher order polynomial collocation method for the numerical solution of 2D and 3D elliptic partial differential equations (PDEs) with variable coefficients. The collocation method with higher order polynomial approximation is very simple for solving PDEs, but it has not become the mainstream method. The main reason is that its resultant algebraic equations have highly ill-conditioned behavior. In our scheme, the multiple-scale coefficients are introduced in the polynomial approximation to overcome the ill-conditioned problem. Based on the concept of the equilibrate matrix, the multiple scales are automatically determined by the collocation points. We find these scales can largely reduce the condition number of the coefficient matrix. Numerical results confirm the accuracy, effectiveness and stability of the present method for smoothed and near-singular 2D and 3D elliptic problems on various irregular domains. [ABSTRACT FROM AUTHOR]

• The UKF with EKRSL is developed by using the fixed-point iteration; • An enhanced EKRSL-UKF is proposed via an exponential function of innovation; • The proposed EnEKRSL-UKF is used for robust DSE. The traditional unscented Kalman filter (UKF) with mean square error (MSE) criterion for dynamic state estimation (DSE) is sensitive for unknown non-Gaussian noise and outliers. Leading to biased state estimates. This paper proposes a novel robust UKF with extended kernel risk-sensitive loss (EKRSL) for DSE considering unknown non-Gaussian process and measurement noises. Instead of MSE criterion, a novel robust EKRSL via the generalized Gaussian density is defined in KRSL framework, and we further develop a new robust UKF using the EnKRSL(called EKRSL-UKF). To obtain the recursive form of EKRSL-UKF, the statistical linear regression model is used and the fixed-point iteration is further utilized to iteratively get the optimal state estimate. An error constrained method is also introduced to restrict the error to address the numerical instability problem caused by large outliers. Furthermore, an enhanced EKRSL-UKF is established by using an exponential function of innovation to improve the estimation accuracy in the presence of noise uncertainties. Numerical results carried out on the IEEE 39-bus test system demonstrate that the proposed method can achieve desired robustness without loss of estimation accuracy under various conditions. [ABSTRACT FROM AUTHOR]