Bond strength estimation plays an important role in structure engineering. This paper proposes to adopt machine learning approaches to conduct a data-driven analysis of bond strength between ...ultra-high performance concrete (UHPC) and reinforcing bars. To make up for the lack of experimental data, a new database is established by integrating 557 instances from several published works. A total of nine machine learning models which can be divided into three types are implemented to train the bond strength estimators based on the database, including linear models, tree models, and artificial neural networks. Four strong metrics, i.e. Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Coefficient of Determination (R2), and Ratio of Accurate Estimation (RACC), are used to evaluate the performance of models. Among them, Artificial Neural Network and Random Forest achieve great estimation performances in the top two, which far exceed the empirical formulas. They have 74% and 73% of estimated data to keep the relative error within 10%, respectively. The statistical relative importance of different factors from tree models consistently shows that the ratio of embedded depth to the diameter of reinforcing bars has a significant impact on the bond strength of UHPC, which is conformable with the observations in experiments.
•The largest database of bond strength between UHPC and reinforcing bars was built.•Nine machine learning models were used to train the bond strength estimator.•The ratio of the embedded depth had a significant effect on the bond strength.
Himawari-8 satellite, equipped with an advanced Himawari imager (AHI), has been widely employed for cloud detection tasks due to its high spatiotemporal resolution. In this paper, we propose a deep ...learning model named dual-branch deformable convolutional network (DBDCN) to detect convective cloud from AHI data. Specifically, we firstly choose some infrared channels from AHI to compute their difference. These brightness temperature difference (BTD) data are sensitive to cloud detection, thus providing complementary information for AHI. Then, both AHI and BTD are used as inputs of DBDCN, which adopts a dual-branch structure to effectively combine them together. Considering that convective clouds often exist variable shapes, we use deformable convolutions to extract convective clouds' features in each branch. Additionally, in order to fuse the complementary features from both branches, we propose a cross-branch fusion block. To evaluate the performance of our proposed DBDCN, we collect a convective cloud dataset, covering most of regions in southern China (i.e., 97<inline-formula><tex-math notation="LaTeX">{}^{\circ }</tex-math></inline-formula>E to 122<inline-formula><tex-math notation="LaTeX">{}^{\circ }</tex-math></inline-formula>E, 20<inline-formula><tex-math notation="LaTeX">{}^{\circ }</tex-math></inline-formula>N to 35<inline-formula><tex-math notation="LaTeX">{}^{\circ }</tex-math></inline-formula>N). Experimental results show that DBDCN is able to achieve better detection performance than the widely used threshold methods and existing convolutional neural networks in most cases.
Bridges designed following a conventional approach minimize the risk of collapse, but often require challenging, costly, and time-consuming restoration after an earthquake occurs. The new seismic ...design philosophy requires bridges to maintain functionality even after severe earthquakes. In this context, this paper proposes a controlled rocking pile foundation (CRPF) system and numerically evaluates bridges′ degree of seismic resilience. The CRPF system allows a pile cap to rock on a pile foundation and dissipate seismic energy through inelastic deformations of replaceable bar fuses that connect a pile cap and piles. Following the conceptual design of the CRPF system, two analytical models were developed for a bridge pier utilizing the CRPF system and a pier designed to develop a plastic hinge in its column. The analytical results indicate that, after experiencing a severe earthquake, a conventionally designed bridge pier sustained substantial damage in its column and exhibited significant residual displacement. In contrast, a pier using the CRPF system showed negligible residual displacement and maintained elastic behavior except, as expected, for bar fuses. The damaged fuses can be rapidly replaced to recover bridge seismic resistance following an earthquake. Therefore, the CRPF system helps to achieve the desired post-earthquake performance objectives.
A deeply buried pipe energy pile (DBP-EP) combines the advantages of a ground source heat pump (GSHP) and an inside buried pipe energy pile (IBP-EP) and is an efficient, clean, and energy-saving ...technology. Based on field tests and numerical simulations, this paper explores the temperature distribution and heat exchange effects of DBP-EP under different influencing factors. The results show that when the pile-to-well ratio is approximately 0.3–0.4, the heat exchange of the energy pile obtains the best benefit; the inlet water temperature is the most significant factor affecting the heat exchange effect of the energy pile, and when combined with a reasonable pile-to-well ratio, the energy pile obtains the best heat exchange effect; the flow rate has a significant impact on the heat exchange effect of the energy pile, but needs to be set reasonably according to the pile-to-well ratio; the influence of inlet water temperature, well depth, flow rate, and pile length on the heat exchange efficiency of the energy pile is gradually weakened. The research results of this paper provide a theoretical basis for the structural design optimization of DBP-EP and promote the popularization and application of energy pile technology.
The seismic performance of ultra-high-performance concrete–high-strength steel pier was studied using fiber elements, which are capable to model accurately elastic–plastic behavior of members with ...fibers of different material constitutive relations. For high-strength steel–ultra-high-performance concrete piers, the modified Kent–Park model was utilized to describe the compressive stress–strain relations of ultra-high-performance concrete and high-strength steel-confined ultra-high-performance concrete, respectively, by determining four key parameters. A finite element model was established to simulate the hysteretic response; conduct parameter analysis including axial load ratio, longitudinal reinforcement ratio, and transverse reinforcement ratio; and assess the maximum ground acceleration capacity based on inelastic response spectra for high-strength steel–ultra-high-performance concrete piers. The conclusions are summarized that modified Kent–Park model is proved to be effective due to experimental data. The calculated hysteretic curves of high-strength steel–ultra-high-performance concrete piers show good agreement with the experimental results. Three parameters have evident effects on seismic performance of high-strength steel–ultra-high-performance concrete piers, which indicates that various seismic demands can be achieved by reasonable parameter settings. Compared to nonlinear dynamic analysis based on finite element model, the results provided by inelastic response spectra are less conservative for short high-strength steel–ultra-high-performance concrete piers under high axial load ratio.
Using pyrrhotite containing aggregates in concrete foundations can lead to premature deterioration visibly identifiable by extensive map cracking, expansion and deformation of the concrete ...foundation. The two main expansion mechanisms are: (1) aggregate expansion induced directly by the oxidation of pyrrhotite inclusions and (2) matrix expansion due to the consequent internal sulfate attack (ISA). The relative contribution of these two mechanisms of expansion were investigated in this study. Theoretical calculations based on the practical combinations of oxidation products and degrees of oxidation indicated that aggregate expansion alone may not be sufficient to cause severe deterioration of the concrete incorporating pyrrhotite-bearing aggregate. Observations and this investigation show that this mechanism leads to microcracking which initiates the deterioration process. The combination of microcracking and the release of sulfate facilitates and intensifies the local ISA. The strain derived from the ISA is substantially higher than the typical ultimate tensile strain of a typical matrix used on foundation walls, thus adding additional mechanical stress on the material, and allowing the development of the typical map cracking throughout the concrete.
The transformation of free state organic micro-pollutants (MPs) has been widely studied; however, few studies have focused on mixed and bound states MPs, even though numerous ionizable organic MPs ...process a strong tendency to combine with dissolved organic matters in aquatic environments. This study systemically investigated the distribution and toxicity assessment of tetracycline (TET) transformation products in free, mixed and bound states during UV, UV/H2O2, UV/PS and CNTs/PS processes. A total of 33 major transformation products were identified by UPLC-Q-TOF-MSMS analysis, combining the double bond equivalence and aromaticity index calculations. The binding interaction would weaken the attack on the dimethylamino (-N(CH3)2) group and induce the direct destruction of rings A and B of TET through the analysis of 2D Kernel Density changes and density functional theory (DFT) calculations. Toxicity assessment and statistics revealed that the intermediate products with medium molecular weight (230≤ m/z ≤ 380) exhibited higher toxicity, which was closely related to the number of the rings in molecular structures (followed as 2»3 > 1≈4). A predicted toxicity accumulation model (PTAM) was established to evaluate the overall toxicity changes during various oxidation processes. This finding provides new insight into the fate of bound MPs during various oxidation processes in the natural water matrix.
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•Total 33 oxidation products varied with TET in free, mixed and bound states.•Binding interaction regularly changed TET degradation pathway during various AOPs.•The binding effect would induce the direct destruction of rings A and B of TET.•Ring number of product structures related to toxicity index fallowed as 2 » 3 > 1≈4.•Proposed PTAM model verified that the products of bound TET were more toxic.
The binding performance of dissolved organic matters (DOM) plays a critical role in the migration, diffusion and removal of various residual pollutants in the natural water environment. In the ...current study, four typical DOMs (including bovine serum proteins BSA (proteins), sodium alginate SAA (polysaccharides), humic acid HA and fulvic acid FA (humus)) are selected to investigate the binding roles in zwitterionic tetracycline (TET) antibiotic under various ionic strength (IS = 0.001–0.1 M) and pH (5.0–9.0). The dialysis equilibration technique was employed to determine the binding concentrations of TET, and the influence of IS and pH on binding performance was evaluated via UV–vis spectroscopy, total organic carbon (TOC), and Excitation-Emission-Matrix spectra (EEM), zeta potentials and molecule size distribution analysis. Our results suggested that carboxyl and phenolic hydroxyl were identified as the main contributors to TET binding based on the fourier transform infrared spectroscopy (FTIR) analysis, and the binding capability of four DOMs followed as HA > FA » BSA > SAA. The biggest binding concentrations of TET by 10 mg C/L HA, FA, BSA and SAA were 0.863 μM, 0.487 μM, 0.084 μM and 0.086 μM, respectively. The higher binding capability of HA and FA is mainly attributed to their richer functional groups, lower zeta potential (HA/FA = −15.92/-13.54 mV) and the bigger molecular size (HA/FA = 24668/27750 nm). IS significantly inhibits the binding interaction by compressing the molecular structure and the surface electric double layer, while pH had a weak effect. By combining the Donnan model and the multiple linear regression analysis, a modified Karickhoff model was established to effectively predict the binding performance of DOM under different IS (0.001–0.1 M) and pH (5.0–9.0) conditions, and the R2 of linear fitting between experiment-measured logKDOC and model-calculated logKOC were 0.94 for HA and 0.91 for FA. This finding provides a theoretical basis for characterizing and predicting the binding performance of various DOMs to residual micropollutants in the natural water environment.
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•Effect of IS and pH on binding performance of four typical DOMs was evaluated.•Binding capability followed as HA > FA » BSA > SAA.•Carboxyl and phenolic hydroxyl were identified as the main contributors to bind.•A modified Karickhoff model was established to predict the binding performance.
A deep buried pipe energy pile (DBP-EP) is a composite structure that integrates ground-source heat pump (GSHP) systems and inside buried pipe energy piles (IBP-EP) to effectively achieve the ...improvement of heat transfer efficiency and quantity. Utilizing this technology in building a pile foundation can contribute to reducing carbon emissions. This paper studies the variation rules of the thermomechanical response of DBP-EP under temperature load via field testing and numerical simulation. The results show that, under heating and cooling conditions, the DBP-EP temperature variation within the pile is substantial, while there is no significant change in the temperature field at the bottom of the pile. This is different from the internal temperature change of the temperature distribution of IBP-EP. The minimum axial average strain of the DBP-EP under the cooling condition is significantly smaller than that under the heating condition. However, the additional axial average strain under the temperature load is significantly larger than that in the heating condition, resulting in larger additional axial stress when the pile is cooled. The connection between the pile and foundation must considered in design due to the large settlement of the pile top under cooling conditions. When only under the temperature load, the maximum axial average pressure increments of the pile in our test during heating and cooling are −85.3 kN/°C and 99.4 kN/°C, respectively, suggesting that the additional load cannot be ignored.
Background Osteoarthritis (OA), a degenerative disease with a high global prevalence, is characterized by the degradation of the extracellular matrix (ECM) and the apoptosis of chondrocytes. Ajugol, ...a extract derived from the herb Rehmannia glutinosa, has not yet been investigated for its potential in modulating the development of OA. Methods We employed techniques such as western blotting, immunofluorescence, immunohistochemistry, X-ray imaging, HE staining, and SO staining to provide biological evidence supporting the role of Ajugol as a potential therapeutic agent for modulating OA. Furthermore, in an in vivo experiment, intra-peritoneal injection of 50 mg/kg Ajugol effectively mitigated the progression of OA following destabilization of the medial meniscus (DMM) surgery. Results Our findings revealed that treatment with 50 muM Ajugol activated TFEB-mediated autophagy, alleviating ER stress-induced chondrocyte apoptosis and ECM degradation caused by TBHP. Furthermore, in an in vivo experiment, intra-peritoneal injection of 50 mg/kg Ajugol effectively mitigated the progression of OA following destabilization of the medial meniscus (DMM) surgery. Conclusion These results provide compelling biological evidence supporting the role of Ajugol as a potential therapeutic agent for modulating OA by activating autophagy and attenuating ER stress-induced cell death and ECM degradation. The promising in vivo results further suggest the potential of Ajugol as a treatment strategy for OA progression. Keywords: Osteoarthritis, Ajugol, TBHP, TFEB, Autophagy, ER stress, DMM
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