Search

• A novel L-shaped composite shear wall composed of a series of columns was proposed. • An experimental investigation of L-shaped composite shear walls under cyclic lateral and axial loads was conducted. • A 3D finite element model, considering improved confinement, plastic hardening, and damage accumulation, can simulate seismic behavior well. • Plastic stress distributed methods were proposed to predict the lateral load strength of an L-shaped steel composite shear wall. Behavior of L-shaped multi-partition steel–concrete composite shear walls (MP-SC-CSWs) subjected to the cyclic lateral load is experimentally and numerically evaluated. Such composite shear walls possess proper capacity, stiffness, and ductility, as the steel tube strengthened by inner steel plates considerably confines the infill concrete. Four large-scale L-shaped MP-SC-CSW specimens were designed, fabricated, and tested. The L-shaped specimens were exposed to lateral hysteretic loading and axial compression loading. The experimental parameters were axial load ratios and height-to-depth ratios (wall aspect ratios). The experimental results indicated that the L-shaped MP-SC-CSWs had high lateral capacities, energy dissipations, and good ductility. Based on the experimental observations, specimens failed in flexure mode. Increasing the axial load ratio enhances the capacity to dissipate energy but decreases the ductility. The tested specimens could meet the drift requirement of the specification even when subjected to a high design axial load ratio of 0.76. Additionally, the wall aspect ratios had little influence on the ductility. 3D nonlinear finite element models of tested specimens were established and verified with test results to conduct further numerical studies. A simplified method based on the plastic stress distribution was developed and confirmed by the experimental and finite element analysis to calculate the flexural capacities of MP-SC-CSWs. [ABSTRACT FROM AUTHOR]

Transcription is a core step in gene expression. Regulation of transcription is achieved at the level of transcription machinery, local chromatin environment as well as higher-order chromatin organization. Our understanding of transcriptional regulation was advanced by recent introduction of transcription and chromatin-associated condensates, which typically arise via phase separation of proteins and nucleic acids. While studies from mammalian cells are unveiling the mechanisms of phase separation in transcription regulation, those in plants further broaden and deepen our understanding of this process. In this review, we discuss recent progress in plants how phase separation operates in RNA-mediated chromatin silencing, transcription activity, and chromatin compartmentalization. [ABSTRACT FROM AUTHOR]

• A new type of l -shaped steel–concrete composite shear wall using multi-partition steel tube was proposed. • The behavior under the eccentric load was investigated by the means of experiments and finite element analysis. • The proposed model using improved constitutional relationship of concrete simulated the eccentric behavior reasonably. • Simplified formulas were proposed to predict the N - M curves, which could consider the influence of load angle and slenderness. An l -shaped composite shear wall, comprised of a multi-partition steel tube and concrete, is developed to improve the behavior of the l -shaped component. It possesses high load-resisting strength and good ductility as it makes better use of steel and concrete. Eleven samples were tested under eccentric load to determine the impacts of the depth, breadth, and load angle. The experimental results showed that the eccentric strength of the specimen under a load angle π was higher than that of the specimen under a load angle of 0. The specimens failed in out-of-plane and in-plane flexural modes when the depth-to-width ratios were different. Then, the finite element (FE) model using an improved constitutional relation of concrete was established to analyze the eccentric mechanism of the l -shaped composite shear walls. Furthermore, parametric analysis using the FE model was taken to determine the key factors of eccentric behavior. Compared to the design methods specified in EC4, AISC, and CECS, it was found that the calculated capacity for the stub was underestimated while the calculated capacity of the slender components was overestimated. The simplified formulas were presented for predicting the N - M curves based on the experimental and FE analysis and it could conservatively include the influence of the load angle and the relative slenderness. [ABSTRACT FROM AUTHOR]

• The sub-cycle voltage disturbance caused by the incipient fault is obtained through experiment. • The waveform and occurrence frequency characteristics of the voltage disturbance are analyzed. • The model and disturbance characteristics indexes of incipient fault sub-cycle disturbance are proposed. Incipient fault is the precursors of permanent cable fault. Analyzing and modeling the transient power disturbances caused by incipient fault is an important prerequisite for accurately identifying incipient cable fault. In this paper, a large number of sub-cycle voltage disturbances caused by the incipient fault are obtained by performing an applying voltage test on a 10 kV cable with local insulation defects. Then, for the voltage signal with disturbance, the time domain analysis method is used to extract the disturbance, and Hilbert transform method and curve fitting method are used to analyze the variation trend of the disturbance. Three stages of the disturbance are obtained: normal stage, fault excitation stage, disturbance attenuation stage. Then an incipient fault sub-cycle voltage disturbance model is proposed and sub-cycle disturbance characteristic indexes which are fault excitation starting time and fault excitation duration are extracted; The validity of the model is analyzed by the reproduced experimental waveform, and the disturbance propagation characteristics along the line are analyzed by PSCAD simulation. [ABSTRACT FROM AUTHOR]

The unmanned combat aerial vehicle (UCAV) path planning problem is a complex global optimization problem that aims to seek an optimal flight route that avoids the threats and constraints on the battlefield. However, as the number and degree of the path threats increases, the recent UCAV path planning algorithms all suffer from being trapped into local optima with a low convergence rate, which leads to the poor performance. Therefore, to resolve these problems, we propose a Cooperative co-Evolution (CE)-based Spider Monkey Optimization (SMO) algorithm, named CESMO to address UCAV path planning problem for avoiding obstacles. First, a cooperative co-evolution strategy is proposed to prevent the algorithms from falling into local optima easily, enhancing the coherence of the path. After that, a further division is applied to the algorithm for diversifying the search direction of each individual in the sub-groups. Finally, the spider monkey optimization-based search mechanism is designed to further strengthen the search efficiency and boost the convergence rate. Experimental results demonstrate that our proposed method is more competitive than other state-of-the-art evolutionary algorithms for UCAV path planning problem considering the quality and stability of the final paths. [ABSTRACT FROM AUTHOR]

Recently, many evolutionary computation methods have been developed to solve the feature selection problem. However, the studies focused mainly on small-scale issues, resulting in stagnation issues in local optima and numerical instability when dealing with large-scale feature selection dilemmas. To address these challenges, this paper proposes a novel weighted differential evolution algorithm based on self-adaptive mechanism, named SaWDE, to solve large-scale feature selection. First, a multi-population mechanism is adopted to enhance the diversity of the population. Then, we propose a new self-adaptive mechanism that selects several strategies from a strategy pool to capture the diverse characteristics of the datasets from the historical information. Finally, a weighted model is designed to identify the important features, which enables our model to generate the most suitable feature-selection solution. We demonstrate the effectiveness of our algorithm on twelve large-scale datasets. The performance of SaWDE is superior compared to six non-EC algorithms and six other EC algorithms, on both training and test datasets and on subset size, indicating that our algorithm is a favorable tool to solve the large-scale feature selection problem. Moreover, we have experimented SaWDE with six EC algorithms on twelve higher-dimensional data, which demonstrates that SaWDE is more robust and efficient compared to those state-of-the-art methods. SaWDE source code is available on Github at https://github.com/wangxb96/SaWDE. [ABSTRACT FROM AUTHOR]

The research has analyzed the axial behavior of an innovative L-shaped composite column. The L-shaped composite columns could work as series rectangular composite columns, which could take advantage of the steel tubes and the inner concrete. Seven specimens have been tested to analyze the failure progress, load-carrying capacity and failure mode. Main parameters were the length-to-width ratio and length-to-depth ratio. The shear failure mode accompanied by local buckling appeared for the tested specimens. The results showed that such columns possessed high strength and good ductility. A finite element model was established and verified by the experimental results. Results showed that the finite element model could simulate the axial behavior of the L-shaped composite columns well. Parametric analysis was conducted to analyze the influence on the axial behavior of composite columns. Furthermore, a theoretical model was proposed to calculate the axial strength of such component and was in good agreement with the experimental results. A simplified formula has been proposed for determining the axial strength according to the results of parametric analysis of FEA and the theoretical model. In addition, the calculated results based on design methods specified in EC4, CECS and AISC have been compared with the experimental results, the results of theoretical model and the results of simplified formula. Among them, the results of EC4 were the closest to the experimental results. [Display omitted] • An innovative multi-partition steel-concrete composite column is proposed. • The axial experiments and finite element analysis have been done to study the axial behavior. • A simplified method has been proposed for the design of the axial strength. • An improved stability factor is added in the simplified formula. [ABSTRACT FROM AUTHOR]

Generalized predictive control (GPC), which has excellent control performance and robustness, is only applicable to the control object that can be expressed in the transfer function and is difficult to be directly applied to the hydraulic turbine regulation system (HTRS) that contain extremely complex nonlinearity. Therefore, considering the practical application of GPC in a hydropower station containing the Francis turbine, the double models, real-time feedback linearization module, and a nonlinear characteristic compensator are designed, and a generalized predictive control strategy combining these modules (GPC-DM-RFLM-NCC) is proposed. Firstly, the salp swarm algorithm (SSA) is improved based on the chaotic mapping and Levy flight, an accurate nonlinear hydraulic turbine model is constructed based on the backpropagation neural network (BPNN) and improved SSA (ISSA), and an HTRS simulation platform with nonlinear characteristics is built by combining modules such as water diversion system, servo system, and generator. Then, the irrationality of the commonly used linear hydraulic turbine models in HTRS dynamic process simulation is verified through quantitative calculation. Furthermore, by combining the real-time feedback linearization method and ISSA-based nonlinear characteristic compensator, the GPC-DM-RFLM-NCC is proposed. Finally, the HTRS simulation platform, which consists of GPC, double models, real-time feedback linearization module, and nonlinear characteristic compensator, is built, and the applicability, reliability, and excellent robustness of the proposed GPC-DM-RFLM-NCC are verified by the real data of a hydropower station. • The salp swarm algorithm is optimized based on the chaotic mapping and Levy flight. • A refined model of the hydraulic turbine regulation system containing the precise hydro-turbine model is established. • The irrationality of the popular linear hydraulic turbine model is revealed through quantitative calculation. • A generalized predictive control strategy is proposed considering the nonlinearity of the hydraulic turbine. • Model mismatch caused by feedback linearization is estimated and corrected. [ABSTRACT FROM AUTHOR]

Aliphatic aldehydes are a class of organic compounds containing aldehyde groups, which are widespread, and closely related to people's daily life and health. In this work, a series of terpenes based hydrophobic deep eutectic solvents were designed and synthesized using hexafluoroisopropanol as hydrogen bond donor and menthol/thymol as hydrogen bond acceptor. Then they are used as extraction solvent in dispersive liquid-liquid microextraction for extracting and determining seven aliphatic aldehydes from drinking water and alcoholic beverage combined with high performance liquid chromatography-ultraviolet. Due to the fact that these hydrophobic deep eutectic solvents are liquid at the room temperature, a density greater than that of water, a lower viscosity (≤26.10 mPa s, 25 °C), after extraction and centrifugation, the microvolume DES-rich phase in the bottom is convenient for collection and direct analysis without further dissolution or dilution with organic solvents. Some factors affecting the extraction recovery were optimized by one-variable-at-a-time and response surface methodology. Under the optimal conditions, the enrichment factors for the seven aliphatic aldehydes were 48–56. The method had good performance: linear ranges of 1.0–200, 0.5–200, 0.2–200, 0.4–400, 1.0–400, 0.4–400 and 0.4–400 μg L−1 for seven aliphatic aldehydes (r 2 ≥ 0.9949), limits of detection of 0.1–0.5 μg L−1, intra-day and inter-day precisions <4.9%. The recoveries of seven aliphatic aldehydes ranged from 76.0 to 119.0%. The proposed dispersive liquid-liquid microextraction method is simple, rapid, highly efficient, and green, which effectively reduces the amount of toxic chemical reagents used and their impact on the environment. Rapid and efficient detection of aliphatic aldehydes helps ensure a healthy diet and has great application prospects in food safety analysis. [Display omitted] • Terpenes based HDESs with low viscosity and high density were designed and prepared. • A terpenes HDESs based DLLME was established for enrichment of aliphatic aldehydes. • The DES-rich phase in the bottom is easy to be collected and directly analyzed by HPLC. • The method is simple, rapid, effective and green for detecting aliphatic aldehydes. • The green profile of the method was assessed by AES and AGREE. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amphiphilic PS-PMMA Janus particles with a distinct morphology were synthesized. • Stabilized Pickering emulsions were prepared using Janus particles. • PS-PMMA is easy to synthesize, inexpensive, and ideal for large-scale production. In this study, two kinds of Polystyrene - Poly(methyl methacrylate) (PS-PMMA) Janus particles with different particle sizes were synthesized via emulsion phase separation using a rotary evaporator. These Janus particles exhibit a distinctive morphology; one side is smooth and crater-like while the other is concave and sprouting. An interplay between device rotation, system stabilization, material hydrophilicity, and strength variation produces this unique morphology. These particles are cost-effective and easy to synthesize, making them ideal for versatile applications in advanced materials. They can form stable Pickering emulsions with liquid paraffin and distilled water, showing remarkable stability and suitability for large-scale production. [ABSTRACT FROM AUTHOR]

To better reveal the nature of gas flow in raw coal and tectonic coal composite seams during gas extraction, experiments on the gas desorption and diffusion kinetic characteristics of raw coal and tectonic coal under different gas adsorption equilibrium pressures were carried out. Meanwhile, the applicability of Airey empirical formula was analysed, and the unipore model and bidisperse model were used to fit the experimental results and calculate the diffusion coefficient. The results show that the initial gas desorption rate and gas desorption volume of raw coal are much smaller than those of tectonic coal at the initial stage of gas desorption; at the later stage, the gas desorption rate of tectonic coal decays rapidly and the ultimate gas desorption volume tends to a stable value, however, the gas desorption rate of raw coal decays slowly and the ultimate gas desorption volume continues to increase. Airey empirical formula has some limitations in characterizing the gas desorption law in coal and is more suitable for fracture-rich "block" coal, but for the tectonic coal, the fitted ultimate gas desorption volume has a significant error from the actual one. The unipore model is suitable for describing some specific periods in the initial stage of the gas desorption process of raw coal, and the bidisperse model makes up for the defects of the unipore model and can accurately describe the gas diffusion law of tectonic coal. The study provides a theoretical basis for the scientific planning of coal and coalbed methane mining. • Compare the differences in gas desorption law of raw coal and tectonic coal. • Airey empirical formula better fits gas desorption in fracture-rich "block" coal. • The limit for using the unipore model and the bidisperse model is studied. [ABSTRACT FROM AUTHOR]

Due to the stochastic grid loads and intermittent renewable energy sources in today's power grid, hydro-generator and grid system stability is increasingly dependent on the hydro-turbine governing system (HTGS). For the HTGS with external disturbances and system uncertainties, an intelligent nonlinear robust controller (INRC) based on state-dynamic-measurement feedback linearization (SDMFL) is proposed to enhance the HTGS's control performance in this paper. This strategy establishes a dynamic output function including actuator displacement, generator rotor angle, and turbine parameters. The relationship between dynamic output and control input is derived based on this function to establish the corresponding linear state-space model. Then, the mixed H 2 / H ∞ robust controller based on the linear model is designed to suppress the effects of external disturbances and system uncertainties on the system performance. In addition, the controller performance is optimized by levy flight and chaos theory-based gravitational search algorithm (LCGSA), resulting in the INRC. Simulations are performed in MATLAB, and the results are compared with the nonlinear robust controller (NRC) and PID controller. The results show that the proposed controller INRC improves the control performance of nonlinear HTGS with smaller overshoot and shorter adjustment time in all cases. • Design of nonlinear robust controller based on SDMFL method for HTGS. • Application of LCGSA algorithm for optimal tuning of NRC parameters. • Damping the speed oscillations against large fluctuations in grid power. • Excellent damping efficiency, especially, low overshoot, steady-state error, and settling time. • Study of robustness of HTGS against variations of system parameters. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel, green and environmental benign TC-AALLME-SFDES technique was developed. • Solid DES was used as extraction solvent. • The method was applied for the determination of TCS and APs from water samples. • The green profile of the method was assessed by analytical Eco-Scale and ComplexGAPI. • The method opened up the application of solid DESs in LLME technique. A novel and green microextraction technique, temperature-controlled air-assisted liquid–liquid microextraction based on the solidification of floating deep eutectic solvents (DESs), was developed and applied for the extraction of triclosan and alkylphenols in different environmental waters. Hydrophobic DESs composed of menthol and myristic acid with melting points slightly higher than room temperature (25 ± 2 °C) were prepared and used as extraction solvent. First, the solid DES was transformed into liquid DES while the aqueous sample was heated in a water bath. Then, fine droplets were formed by withdrawing and injecting the mixture of aqueous sample and DES with a 1 mL pipette several times. After extraction, the solidified DES phase was obtained in an ice water bath. And then the analyses were performed by HPLC-UV. The microextraction parameters were investigated by the Plackett-Burman design and central composite design. The analytical parameters of this method were investigated and good linear ranges (0.5/1.0–400 μg/L, R2 ≥ 0.9950), limits of detection (0.1–0.5 μg/L) and precision (≤5.9 %) were obtained. This method was successfully applied for the determination of triclosan and alkylphenols from five water samples with satisfactory recoveries (80.0–104.3 %). Subsequently, the green profile of the method was assessed by analytical Eco-Scale and Complementary Green Analytical Procedure Index. This method has the advantages of simplicity, rapidity, low cost, high sensitivity and green, which expands the application of solid solvents in liquid–liquid microextraction and has a wide application prospect. [ABSTRACT FROM AUTHOR]

• One-step derivatization and TC-VA-LLME-SFDES method was developed. • Hydrophobic DESs were used as both reducing agent and extraction solvent. • Only 2 min was needed for derivatization and extraction process. • The method was applied for analysis of total Fe in water and food samples. • The method opened up the application of solid DESs in LLME technique. In our work, hydrophobic thymol-based deep eutectic solvents (DESs) with strong reducibility, a lower density than water, and a slightly higher melting point than room temperature were synthesized. Based on these solid DESs, one-step derivatization and temperature-controlled vortex-assisted liquid-liquid microextraction based on the solidification of a floating DES (TC-VA-LLME-SFDES) via UV–Vis spectrophotometry for the rapid determination of total iron was developed. The derivatization and TC-VA-LLME were carried out simultaneously by the addition of DES as both the reducing agent and extraction solvent. After optimization, the calibration curve (5–250 μg L−1, R2 = 0.9982), limit of detection (1.5 μg L−1), limit of quantitation (5.0 μg L−1), precision (≤4.0%) and enrichment factor (92) was obtained. This method was applied for the determination of total iron in water and food samples with satisfactory recoveries (85.4–106.2%). One-step derivatization and TC-VA-LLME only required 2 min. Furthermore, this method opened up the application of solid DESs in liquid–liquid microextraction. [ABSTRACT FROM AUTHOR]

In recent years, contrastive learning has made great progress in the field of computer vision, which shows great potential in action representation learning. Current contrastive learning methods usually employ contrastive loss function to learn video motion representation, which attend to capturing the similar background appearance but ignore similar motion information. This problem is called background bias, which restricts the model from exploring motion patterns. The background bias can be divided into wide background bias and micro background bias. The wide background bias refers to the statistically significant background bias, while the micro background bias refers to the background bias directly interacting with the moving object. To tackle these problems, this paper first proposes a semi-negative pair merging foreground–background, which mainly decouples the dynamic factor with obvious motion and the static factor with stable invariants in the video frame sequence. Then the dynamic factor of the original video is fused with other static factors to obtain a random background image where the foreground is more similar than the background to solve the wide background bias. Secondly, a pixel-level motion aware representation decomposition module calculates the pixel-level intensity variations from the feature space of adjacent frames, and these variations are further accumulated to obtain the salient map that focuses on the boundaries of moving objects, so the model attends to the motion pattern rather than the background to solve the micro background bias. Furthermore, a new dual loss function is proposed based on joint wide and micro background bias to better capture both static and dynamic features. The heat map shows that the proposed method effectively can solve background bias and achieve better performance in public datasets compared with other existing methods. [ABSTRACT FROM AUTHOR]

T-shaped welded multi-partition composite members, which are made of several rectangular concrete-filled steel tubes, are proposed to speed up the fabrication procedure. Seven half-scale T-shaped specimens were tested by considering the section height-to-width ratio and slenderness ratio. In the test, a slight torsion angle was measured when the instability failure along the asymmetric axis occurred, indicating the specimens had good torsion resistance. When the relative slenderness ratio of the specimen was larger than 0.44, the specimens failed due to the instability along the asymmetric axis. Parametric numerical analysis is conducted by considering the slenderness ratio, cross-section dimension, steel ratio, and material strength. The results show that the strength of concrete negatively impacts the ductility of the specimens, leading to a decrease of 43%, while the strength of the material positively influences the stability of the specimens. The formulas from different traditional codes are verified by the parametric numerical analysis results, indicating most codes can conservatively predict the sectional bearing capacity, but overestimate the stability coefficient of the specimens by neglecting the reduction effect of the excessive height-to-depth ratio. Recommendations are provided for calculating the stability coefficient under axial compression applicable to T-shaped welded multi-partition composite members. • Axial compression of T-shaped welded multi-partition composite members was studied through experiments and FE analysis. • The measured torsion angle confirms the good torsional capacity of T-shaped composite members. • Both sectional bearing capacity and stability bearing capacity have been discussed. • A suggestion for calculating stability coefficients is proposed, which is suitable for T-shaped columns and shear walls. [ABSTRACT FROM AUTHOR]

Single measures of adiposity markers, such as body mass index (BMI) and waist circumference (WC), are associated with adverse mental health outcomes; however, long-term patterns of adiposity and their health effects remain unclear. The current study assessed adiposity trajectories during a 14-year span beyond middle age and their relevance to mental well-being in late life, and the contribution of genetic and lifestyle factors to the trajectories. Based on a nationally representative sample with longitudinal anthropometric measures, adiposity trajectories were identified by latent mixture modeling, and logistic regression model was used to estimate their associations with mental well-being, with adjustment for confounders. Of the 3491 eligible participants included (mean [SD] age, 69.5 [8.9] years), five discrete BMI and four WC trajectory patterns were identified over 14 years. Compared with the low-stable BMI group (range, 22.8 to 22.9 kg/m²; representing stable healthy body weight), the high-stable group (range, 34.3 to 35.4 kg/m²; stable obese) was associated with increased risk of depression (odds ratio [OR], 1.63; 95 % CI, 1.28–2.07) and low subjective well-being (OR, 1.35; 95 % CI, 1.02–1.79). Compared with the low-stable WC group (range, 75 to 79 cm healthy WC), the high-increasing group (range, 114 to 121 cm) was associated with increased risk of depression (odds ratio [OR], 1.64; 95 % CI, 1.19–2.25) and low well-being (OR, 1.48; 95 % CI, 1.01–2.16). The adiposity trajectories, especially the high-stable/increasing groups, were driven by genetic factors in a dose-response manner, whereas the high/moderate-increasing groups were also behaviorally related. This longitudinal cohort study reveals that stably high trajectory patterns of central and general adiposity during middle age were associated with higher risk of depression and low well-being in late life. The findings indicate the importance of weight management beyond middle age, such as adherence to a healthy lifestyle, in promoting mental health and well-being. [ABSTRACT FROM AUTHOR]

Neural architecture search (NAS) is to automatically design task-specific neural architectures, whose performance has already surpassed those of many manually designed neural networks. Existing NAS techniques focus on searching for the neural architecture and training the optimal network weights from the scratch. Nevertheless, it could be essential to study how to tune a given neural architecture instead of producing a completely new neural architecture in some scenarios, which may lead to a more optimal solution by combining human experience and the advantages of the machine's automatic searching. This paper proposes to learn to tune the architectures at hand to achieve better performance. The proposed Neural Architecture Tuning (NAT) algorithm trains a deep Q-network to tune neural architectures given a random architecture so that we can achieve better performance on a reduced space. We then apply adversarial autoencoder to make the learned policy be generalized to a different searching space in real-world applications. The proposed algorithm is evaluated on the NAS-Bench-101 dataset. The results indicate that our NAT framework can achieve state-of-the-art performance on the NAS-Bench-101 benchmark, and the learned policy can be adapted to a different search space while maintaining the performance. [ABSTRACT FROM AUTHOR]

The combustion mechanism and gaseous products of asphalt binder at five different oxygen concentrations (21%, 18%, 15%, 12%, and 10%) were studied by thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR). The evolution of the functional groups and microscopic morphology of condensed phase were also analyzed by infrared spectroscopy (IR) and scanning electron microscopy (SEM). The semi quantitative research was realized by calculating the absorption peak area of IR, proximate and ultimate analyses. Results show that the oxygen concentration influences both the pyrolysis and combustion stages of asphalt, and the influence on the combustion of heavy components is more significant. With the decrease of oxygen concentration, the residual mass after the combustion of asphalt binder increases. Additionally, the temperature zone of combustion shifts higher, and a thermal reaction lag effect becomes more obvious. The concentration of oxygen only changes the concentration of gaseous products, instead of the types. Moreover, the concentrations of CO 2 , CO, H 2 O, SO 2 , etc. all decrease, and there is the biggest drop in CO 2. The low oxygen concentration inhibits the dehydrogenation reaction of asphalt in the aerobic pyrolysis stage, while the complete combustion of asphalt residues is inhibited in the combustion of heavy components stage. These will all provide more scientific basis for the analysis of asphalt combustion under low oxygen conditions in tunnel fires. • Combustion mechanism of asphalt binder under different oxygen concentration was discussed. • Dynamic evolution of volatiles released from asphalt binder combustion at different oxygen concentration was described. • Evolution of functional groups in the condensed phase of asphalt binder was analyzed. • Combustion mechanism of asphalt binder under low oxygen conditions was further understood. [ABSTRACT FROM AUTHOR]

This study experimentally and numerically explores the axial-compression behaviours of tapered recycled aggregate concrete-filled high-strength double skin steel tubular (RAC-FHDST) stub column. Twelve specimens were fabricated and tested, considering the effects of tapered angle, hollow ratio and replacement level of coarse recycled aggregate (CRA). The experimental results, consisting of deformation patterns, axial load versus strain responses and confining effect from external high-strength steel tube were obtained and analyzed. Failure mode showed that all stub columns exhibited good ductile behaviour. The elastic stiffness and ultimate strength of RAC-FHDSTs decreased with rising tapered angles, while the ductile index increased. As the replacement levels of CRA varied from 0% to 100%, the elastic stiffness and ductility index obviously reduced. Larger confining effect from outer steel tube to RAC occurred close to the top section of specimens, and the occurrence of confinement was advanced with decreasing hollow ratio and increasing CRA content. Additionally, detailed numerical models were constructed and validated using experiment results. The validated finite element (FE) models were then employed to analyze the working mechanism of specimen, encompassing the load distributions and the interaction between the sandwiched RAC and steel tubes. Afterwards, a parametric study was performed to reveal the influences of essential parameters on the axial compressive performance. Finally, the existing design approaches to normal CFST and CFDST stub columns were employed to assess their applicability for estimating the ultimate strengths of tapered RAC-FHDSTs. • Axial-load tests conducted on 12 RAC-FHDST stub columns. • Effects of tapered angle, hollow ratio and CRA content on the axial response of RAC-FHDSTs. • Confinement effect from outer high-strength steel tube. • The applicability of existing design provisions to tapered RAC-FHDSTs. [ABSTRACT FROM AUTHOR]

Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), as emerging endocrine-disrupting chemicals (EDCs), pose adverse effects on aquatic organisms. Conventional ecological risk assessment (ERA) not fully considering the mode of toxicity action of PFOS and PFOA, may result in an underestimation of risks and confuse decision-makers. In the study, we developed species sensitivity weighted distribution (SSWD) models based on adverse outcome pathway (AOP) networks for deriving predicted no-effect concentrations (PNECs). Three kinds of weighting criteria (intraspecies variation, trophic level abundance, and data quality) and weighted log-normal distribution methods were adopted. The developed models considered the inter/intraspecies variation and integrated nontraditional endpoints of endocrine-disrupting effects. The PNECs of endocrine disruption effects were derived as 2.52 μg/L (95% confidence intervals 0.667–9.85 μg/L) for PFOS and 18.7 μg/L (5.40–71.0 μg/L) for PFOA, which were more conservative than those derived from the SSD method and were comparable with the values in the literature based on the chronic toxicity data. For PFOS, the effect of growth and development was the most sensitive; however, for PFOA, the effect of reproduction was the most sensitive in the effects of growth and development, reproduction, biochemistry and genetics, and survival. The endocrine-disrupting effects of PFOS and PFOA are significant and need to be fully recognized in the ERA. This study provided an ERA framework that can improve the ecological relevance and reduce the uncertainty of PNECs of EDCs. [Display omitted] • SSWD considers the inter/intraspecies variation and data quality of toxicity. • AOP network integrates endocrine disruption effects of muti-biological levels. • PNECs of endocrine disruption effects as 2.52 (PFOS) and 18.7 (PFOA) μg/L. • SSWD-based PNECs are more conservative than those from SSD models. • AOP-SSWD improves ecological relevance and reduce uncertainty of PNEC. [ABSTRACT FROM AUTHOR]

• Impact-resistant behaviours of steel–concrete composite wall with recycled aggregate concrete. • Time histories of impact force and deformation, and failure mode. • Effects of CRA content, material strength, steel plate ratio, tie-bar spacing, impact energy and axial load ratio on the impact response. • Single degree of freedom approach used to predict the displacement response. This paper investigates the impact-resistant behaviours of steel–concrete (SC) composite walls experimentally and numerically, which consist of two outer steel plates and infilled recycled aggregate concrete (RAC). Totally eight SC walls were designed and fabricated with different coarse recycled aggregate (CRA) content and steel plate thicknesses. Drop-hammer impact testing was first performed to obtain the failure mode, impact force and deformation. Test results indicated that the impact resistance behaviour of SC walls enhanced considerably with a decrease in CRA content. The tie bars combined with studs were effective to avoid the separation of steel plate from the concrete core. Afterwards, the finite element (FE) models were developed and calibrated, and then used to obtain more information on the full-range motion response, development of stress and strain, and energy absorption. In addition, the influences of different parameters, including the CRA content, material strength, steel plate ratio, tie-bar spacing, impact energy and axial load ratio on the impact resistance performance were assessed. Finally, the displacement response of SC composite walls with RAC was predicted using single-degree of freedom (SDOF) approach. [ABSTRACT FROM AUTHOR]

Five specimens have been tested under cyclic lateral loads to explore the seismic behavior of T-shaped multi-partition steel–concrete shear walls along the asymmetrical axis. The loading has been applied by considering the torsion effect from non-coincidence between the lateral loads and the shear center in this study. The main parameters of the test are the axial compression ratio and section height-to-breadth ratio aiming to study the vertical load and web constraint effect. The test results indicate that the failure mode of all specimens along the asymmetric axis is bending failure with minor shear deformation measured during loading. The yield drift (1/138) and the ultimate drift (1/41) of the T-shaped multi-partition steel–concrete shear walls could meet the requirement of the corresponding code, namely 1/350 and 1/70, respectively. The increase in axial compression ratio increases the out-of-plane displacement but decreases the ductility of the specimens, whilst the increase in section height-to-breadth ratio decreases the out-of-plane displacement of the specimens. The relatively small torsion angle of less than 0.6° indicates that the T-shaped multi-partition steel–concrete shear walls have good torsion resistance. Under the cyclic lateral loads along the asymmetrical axis, the out-of-plane displacement of the T-shaped specimen will occur on the side without the web. The web elastic stress distribution model can predict the lateral resistance more accurately, whilst the full-section plastic stress distribution model overestimates the lateral resistance of T-shaped multi-partition steel–concrete shear walls. • T-shaped multi-partition steel–concrete shear walls were tested under asymmetrical loads. • The ductility of T-shaped composite shear walls meets the requirement in Chinese code. • The measured torsion angle confirms the good torsional capacity of T-shaped composite shear walls. • The flange of T-shaped walls is under additional loads due to the out-of-plane deformation. • The web elastic stress distribution model is more suitable to predict the lateral resistance of the specimens. [ABSTRACT FROM AUTHOR]

• Coupling the traditional mechanical rolling and high frequency ultrasonic vibration process. • Numerical analysis and research on the residual stress and surface roughness of the processed components. • Explore the influence of different process parameters on component residual stress and surface roughness. In order to improve the surface performance of the key components of Ti-6Al-4 V titanium alloy and meet its requirements for surface performance and life in complex service environments, this study combines traditional mechanical rolling with high-frequency ultrasonic vibration, and achieves high-speed impact on the surface of titanium alloy and traditional rolling at the same time. Numerical simulation of ultrasonic rolling processing of titanium alloy workpiece is carried out, the residual stress and surface roughness of the workpiece after processing are analyzed, and the influence of different process parameters on it is explored. The results show that ultrasonic rolling processing can effectively improve the surface properties of Ti-6Al-4 V titanium alloy, so that the residual stress distribution of the workpiece is more uniform and increases with the increase of static force and amplitude. When the static force is 1000 N and the amplitude is 8 μm, the surface finishing effect is the best. [ABSTRACT FROM AUTHOR]

Materials and structures with enhanced energy-absorbing and impact perception capabilities are widely deployed for crash mitigation, protective packaging of sensitive elements, and personal impact protection. However, conventional lightweight structures with a monolithic constitutive material cannot simultaneously achieve exceptional energy-absorbing capacity and electromechanical sensitivity. Here we proposed a new class of architected ceramic-polymer composites with improved energy-absorbing capacity and piezoelectric performance. An interconnected porous lead zirconate titanate ([Pb(Zr 0.52 Ti 0.48)O 3 ], PZT) skeleton with uniformly distributed cellular-like pores in the transverse section and directionally aligned porous structure in the longitudinal section was fabricated using a facial camphene-templated freeze-casting method. Subsequently, the polymeric polydimethylsiloxane (PDMS) was impregnated into the skeleton to form the three-dimensional (3-D) interpenetrating-phase piezoelectric composite (IP3C). The as-fabricated interpenetrating architecture with each phase interconnected has endowed the proposed IP3C with an unprecedented combination of mechanical-damping (energy-absorption efficiency ∼ 7.71 MJ m−3) and electromechanical-conversion (piezoelectric constant d 33 ∼ 146 pC N−1) properties, which are 9 times and 7 times higher than the conventional counterpart 0–3 piezoelectric composite, respectively. As evidenced by numerical simulations, this remarkable enhancement is attributed to the high stress transfer efficiency within the IP3C, which is intrinsically controlled by the rationally designed interpenetrating architecture. The findings reported here demonstrate that multifunction, e.g., exceptional energy absorption and high sensitivity, can be achieved in one composite with architecture design, thereby driving forward and expanding the fundamental understanding in the area of multifunctional materials in hostile loading environments. • An interconnected porous lead zirconate titanate ([Pb(Zr 0.52 Ti 0.48)O 3 ], PZT) skeleton with uniformly distributed cellular-like pores in the transverse section and directionally aligned porous structure in the longitudinal section was fabricated using a facial camphene-templated freeze-casting method. • The as-fabricated interpenetrating architecture with each phase is interconnected has endowed the proposed IP3C with an unprecedented combination of mechanical-damping and electromechanical-conversion properties, which are 9 times and 7 times higher than the conventional counterpart 0–3 piezoelectric composite, respectively. • The findings reported here demonstrate that multifunction, e.g., exceptional energy absorption and high sensitivity, can be achieved in one composite with architecture design, thereby driving forward and expanding the fundamental understanding in the area of multifunctional materials in hostile loading environments. [ABSTRACT FROM AUTHOR]