Multi-factor Coupling Research Articles

Study on the correlation between indoor accelerated corrosion testing of concrete epoxy polysiloxane coating and real-sea environmental testing in the East China Sea

In order to reveal the correlation between the accelerated corrosion test of epoxy polysiloxane coating and the real sea environmental test, the real sea environmental test was carried out in the atmosphere and tidal range area of Zhairuoshan Island in the East China Sea, and the multi-factor coupling test I (Cycle of 7-day xenon lamp aging test + 7-day Wetting-drying test) and test II (Cycle of 7-day xenon lamp aging test + 3-day damp heat test + 4-day salt spray test) were designed with reference to the environment of the East China Sea. The correlation between indoor accelerated corrosion test and real sea environmental test was analyzed by using Grey Relation Analysis, Spearman's rank correlation coefficient and Acceleration factor conversion method. The results show that both the indoor accelerated corrosion test and the real sea environmental test have corrosive effects on the epoxy polysiloxane coating of concrete. In the indoor accelerated corrosion test, it was found that the Wetting-drying test caused the highest loss of light rate. In the real sea environmental test, the loss of light rate of the coating in the atmosphere is higher than that in the tidal area, and the color difference is slightly lower. When the loss of light rate is used as the criterion, the grey correlation coefficient between the multi-factor coupling test I and the tidal range test is 0.63, and the maximum acceleration factor during the test is 5.3, indicating a good correlation between the two tests. Through this study, an effective indoor accelerated corrosion test method with good correlation and acceleration characteristics to the loss of light rate of concrete epoxy polysiloxane coating in a real sea environment was obtained.

Thermal decomposition mechanism and characterization of phosphogypsum in suspension under multifactor coupling effect

Phosphogypsum (PG) is solid waste generated by the phosphate fertilizer industry. However, by high-temperature thermal treatment, it can be effectively decomposed into byproducts like SO2 and CaO, which are valuable raw materials for the production of sulfuric acid and construction materials, respectively. In this study, we investigated the thermal decomposition properties of suspended PG, as well as the factors governing the PG decomposition procedure. The results show that the PG decomposition rate was influenced by several parameters, with temperature being the most significant, followed by time, atmosphere, and charcoal powder dosing. Similarly, the desulfurization rate was primarily influenced by time, followed by temperature, atmosphere, and charcoal powder dosing. The PG exhibited maximum decomposition and desulfurization rates of 97.73% and 97.2%, respectively, at a calcination temperature of 1180 °C, a calcination period of 15 min, a carbon powder dosage of 4%, and a CO concentration of 6%. Kinetic studies revealed that the activation energy of the PG decomposition reaction decreased from 303.45 to 254.28 kJ/mol as the CO concentration increased from 4% to 6% upon addition of charcoal powder as a reducing agent. Furthermore, higher CO concentrations had a more pronounced effect on lowering the activation energy of PG pyrolysis. When the contents of SiO2 and Al2O3 impurities in the PG content were higher, they reacted with CaO in the decomposition products to produce silicate and aluminate minerals, respectively, decreasing both the CaO content in the product and the PG decomposition rate.

Sensitivity analysis of underwater launch based on Morris method

The discharge velocity, pressure difference and acceleration of underwater launch performance are affected by many factors, including depth, sailing speed, burning rate, water temperature, density and other operating parameters. The existing underwater launch sensitivity analysis is a local sensitivity qualitative analysis based on single-step perturbation analysis, which can only investigate the influence of a single uncertain factor on the model results in a small range. In this paper, based on the underwater launch model under multi-factor coupling, 10 input parameters were selected to calculate the multi-factor sensitivity of the underwater launch model based on the three objectives of velocity, pressure difference and acceleration at the time of discharge, and the Morris global sensitivity analysis method was used to calculate the sensitivity of the underwater launch model, and the sensitivity of the 10 input parameters to the model results was sorted. The results show that the five input parameters of burning rate, depth, propellant temperature, density and water temperature have the highest sensitivity to velocity, pressure difference and acceleration, and the sensitivity order is slightly different. The influence of water temperature on the three targets is almost evenly distributed in the range of values, and the other parameters have different sensitive ranges for different targets.

Research on multi factor coupling accident triggering mechanism and accident risk control of gas pipeline leakage

Research on multi factor coupling accident triggering mechanism and accident risk control of gas pipeline leakage

Research on energy efficiency and decarbonization pathway of nearly zero energy buildings based on system dynamic simulation

Accounting for over 40% of the total energy consumption, the global building sector is pivotal for achieving carbon peak and neutrality objectives. The intricate nature of building carbon emissions, influenced by spatial, temporal, and multifactor coupling, poses challenges on implementing carbon-neutral technologies and conservation strategies. This study focuses on nearly zero energy buildings in China and employs system dynamics to predict energy consumption and carbon emissions according to various scenarios, unveiling influencing patterns and viable emission reduction pathways. The results highlight the substantial impact of enhancing energy conservation awareness as this leads to a 36.4% reduction in energy consumption and a 44.2% reduction in carbon emissions. To attain energy efficiency and carbon reduction goals, a comprehensive approach is essential, encompassing improved building performance, heightened resident energy awareness, increased renewable energy use, and energy landscape adjustments. These findings inform future building energy and carbon emission regulations and offer valuable policy insights.

Milling Stability Prediction under Multi-effect Synergy

During the milling process, chatter vibration is prone to occur when the spindle, tool, and workpiece interact with each other under certain parameters, which seriously affects machining efficiency and reduces machining quality. Therefore, it is necessary to study the mechanism and influencing factors of chatter vibration, predict the stability of the milling system through a multi-effect synergistic dynamic model, and obtain the machining parameters of stable milling through analysis. Based on the traditional milling model, this article considered the regeneration effect, process damping effect, and modal coupling effect, and also considered the friction effect of the front cutting surface for friction-induced chatter, to make the model’s prediction range more accurate. Then, a milling dynamic model was established combining multiple effects, and its stability lobe diagrams were solved by the full-discretization method. The accuracy of the model was verified through milling stability experiments. The experimental results are basically consistent with the predicted stability lobe diagrams, indicating that the milling stability prediction model considering multi-factor coupling of the milling model is correct. Finally, the influence of various effects on milling stability was analyzed, with a focus on the influence of friction effects.

Analysis and prediction of hydrogen-blended natural gas diffusion from various pipeline leakage sources based on CFD and ANN approach

The influences of pipeline leakage source types on the hazard area distribution caused by accidental hydrogen-blended natural gas leakage are still the focus of gas leakage accidents. Three types of pipeline leakage sources are discussed in this study. Namely, the gas in the vertical pipeline flows from top to bottom, and the leakage orifice is in the pipeline wall; the gas in the vertical pipeline flows from bottom to top, and the leakage orifice is in the pipeline wall; the leakage orifice is in the horizontal pipeline end. The common feature of the above three pipeline leakage sources is that the normal of leakage orifice is parallel to the horizontal plane. The differences in the flow field distribution of hydrogen-blended natural gas released from three pipeline leakage sources are compared through numerical simulation. The effect of various factors on the jet centerline, concentration decay, and maximum horizontal diffusion distance of hydrogen-blended natural gas released from three pipeline leakage sources are analyzed. The predictive models of hydrogen-blended natural gas's maximum horizontal diffusion distance in three pipeline leakage sources under multi-factor coupling are established through a backward propagation neural network (BPNN). Results show that the angle between the gas flow direction in the pipeline and the normal of the leakage orifice, and the background step flow cause differences in the concentration field near the leakage orifice from the three pipeline leakage sources at the same working conditions. In the near-field region, the leakage orifice diameter has the most significant influence on the jet centerline of three hydrogen-blended natural gas jets among three factors. The concentration decay rate of gas released from the horizontal pipeline end is greater than that of gas released from the other two pipeline leakage sources. With the increase of volumetric flow rate, the maximum horizontal diffusion distances of methane released from three pipeline leakage sources all increase, while the maximum horizontal diffusion distances of hydrogen released from three pipeline leakage sources have little change. The predictive models of the maximum horizontal diffusion distance of hydrogen-blended natural gas released from three pipeline leakage sources are established through BPNN. The maximum horizontal hazard distances of the new working conditions are predicted, and the predicted results are in good agreement with the numerical simulation results. This investigation has guiding value for fast and accurate prediction of flammable gas hazard areas.

Properties deterioration of recovered bitumen under coupling multi-environment factors based on the ageing simulation device

The properties of pavement bitumen deteriorates when exposed to complicated environmental factors. This study developed a multi-environment simulation device to apply multi-factor coupling on asphalt mixtures. The physicochemical properties of recovered bitumen were analysed by traditional technical indicators, tensile strength, fourier transform infrared spectroscopy, and contact angle tests. The ageing index and target functional group index ratio were proposed to quantify the interactions of environmental factors. The results indicated that surface morphology of mixtures was severely affected by multi-factor coupling. The multi-factor coupling exacerbated the deterioration of physical properties and increased tensile strength, surface free energy, and adhesion work. However, the sulfoxide index was more affected by thermal ageing than the carbonyl index, and its change under ultraviolet and multi-factor actions was not obvious. The ageing index and target functional group index ratio indicated that the effect of ultraviolet-thermal coupling had the largest effect on the physicochemical properties of bitumen.

Thermoelastoplastic hydrodynamic lubrication contact analysis of three dimensional rough tooth surface considering micro-scale effect and thermal effect

The contact properties of gear rough surfaces during meshing are influenced by various factors. The analysis of rough surface thermoelastoplastic hydrodynamic lubrication (TPEHL) considering micro-scale effect and thermal effect has not been addressed in the literature. This study establishes a new TEPHL model with multi-factor coupling of thermal field, fluid lubrication, stress-strain, and geometric profile. Based on strain gradient theory (SG), a new thermoelastoplastic material constitutive considering micro-scale effect is developed. Subsequently, the three-dimensional rough surface TPEHL-SG analysis of gear is conducted. The paper investigates the impact of thermal and micro-scale effects on various parameters during the meshing of gear in the full oil film lubrication condition, including surface pressure, oil film thickness, surface temperature, surface deformation, and friction coefficient.

Multidimensional Transport Experiment and Simulation of Chloride Ions in Concrete Subject to Simulated Dry and Wet Cycles in a Marine Environment.

Chloride ion erosion is an important factor affecting the durability of marine engineering concrete. In particular, concrete structures in wave splash and tidal zones are subjected to dry and wet cycles and multidimensional diffusion of chloride ions. To investigate the intricate diffusion of chloride ions within concrete under these dynamic conditions, we devised a comprehensive experiment. This experiment encompasses multiple dimensions, involving dry and wet cycles, as well as static immersion. The experiment intends to reveal how chloride ions are distributed in the concrete and clarify the changes that occur in its microstructure. Based on Fick's second law, the multidimensional diffusion model of chloride ions in concrete under the dry and wet cycles and static immersion was established by comprehensively considering the effects of chloride ion exposure time, environment temperature, relative humidity, and the action of dry and wet cycles. The results show that, under the same conditions, the chloride content in concrete decreases with the increase in penetration depth but increases with the increase in the chloride diffusion dimension and exposure time. Dry and wet cycles and multidimensional diffusion of chloride ions increase the development of cracks and pores in the concrete structure and generate large quantities of C3A·CaCl2·10H2O, which will exacerbate the chloride ion transport rate and penetration depth of concrete. Under the same exposure time and penetration depth, the chloride ion content in concrete under two-dimensional (2D) and three-dimensional (3D) diffusion under dry and wet cycles was 1.09~4.08 times higher than that under one-dimensional (1D) diffusion. The correlation coefficients between the simulation results of the multidimensional transport model of chloride ions in concrete under multi-factor coupling and the experimental results were all greater than 0.95, and the model can be utilized to predict the distribution of chloride ion concentration in concrete.

Optimisation of stable flight posture of ski jumping based on computational fluid dynamics simulation technology

ABSTRACT The stable flight posture that affects sports performance during flight is usually formed by the multiple angles of the athlete—ski posture. At present, research on the flight phase is mainly based on the single-factor impact analysis based on computational fluid dynamics simulation technology, but studies on the multi-factor coupling relationship of two or more factors is less. This study aims to determine the best optimal-level combination based on the simulation model of this work through comprehensive evaluation from the optimisation perspective of multi-factor coupling. Here, a refined model of the athlete—ski system with the characteristics of ski jumping was established. Reynolds time-averaged method was used for the simulation. A three-factor and five-level simulation test was conducted on the relative inclination between skis, the angle between the body and the ski and the ski V-angle through orthogonal experiment design. Our results show that the optimal-level combination of the relative inclination between skis of 120°, the angle between the body and the ski of 20°, and the ski V-angle of 30° is relatively best in terms of aerodynamic characteristics. Simulation results were similar to the results of the winter field data from video analysis, and the results were effective.

Synergistic Effects of Multiple Environmental Factors on Degradation of Silicone Rubber Seals under Marine Atmosphere.

In this research, the degradation behavior and failure mechanism of silicone rubber seal rings under the synergistic effects of multiple factors in the marine atmosphere are fully investigated. Firstly, four aging factors of air, temperature, compressive stress, and chemical medium were determined by analyzing the service environment profile of silicone rubber seal under a marine atmosphere environment. Secondly, to better simulate the actual service environment of silicone rubber and shorten the test period, an artificially accelerated aging test was designed and carried out in the laboratory. In this paper, temperature is utilized as the accelerating stress. According to the results of the pre-test, the accelerating stress level is finally determined to be 110-150 ∘C. In addition, the compression set applied is consistent with the constant compression permanent deformation value of 28% of the silicone rubber in the actual service process. Finally, through the macroscopic physical properties and microstructure analysis of the samples before and after aging, the corresponding test results are given, and the failure mechanism is analyzed and discussed in detail. Through the above test results and discussion, it can be concluded that the aging process of multi-factor coupling on the lower silicone rubber seal ring is uneven, and its aging process is not a simple superposition of multiple environmental factors. More importantly, the above test data and results are of great significance for evaluating the service life of silicone rubber seals, which can be utilized in the future to improve the reliability and durability of related equipment in the marine environment.

Thermal Equilibrium Analysis of Small-to-Medium River Ecosystems in Northern China under Multi-Factor Coupling and Decision-Making for Ecological Restoration

Thermal Equilibrium Analysis of Small-to-Medium River Ecosystems in Northern China under Multi-Factor Coupling and Decision-Making for Ecological Restoration

Machine learning aided uncertainty analysis on nonlinear vibration of cracked FG-GNPRC dielectric beam

Functionally graded graphene nanoplatelet reinforced composite (FG-GNPRC) have shown significant potential for the development of high-performance and multifunctional materials and structures. Conducting an accurate analysis of the nonlinear vibration of FG-GNPRC dielectric beams can accelerate their application in various engineering fields. To investigate the nonlinear vibration of FG-GNPRC dielectric beams, the effective material properties of a cracked composite beams are evaluated using effective medium theory (EMT) and the rule of mixture. Three ML models adopted in this work, i.e., artificial neural network (ANN), random forest (RF), and AutoGluon (AG), are used to capture the complex relationship between the systematic inputs (i.e., parameters for materials and structure, the attributes of electrical field, etc.) and frequency ratio of the cracked FG-GNPRC beams. Moreover, shapley additive explanations (SHAP) is employed for the analysis of the nonlinear vibration of FG-GNPRC dielectric beams considering the influence of multi-factor coupling and uncertainties. The SHAP analysis suggests that the uncertainty of structural parameters has the greatest impact on the nonlinear vibration of FG-GNPRC dielectric beams, particularly when the structure is subjected to a voltage of 40 V.

Multi-Temporal Change of LULC and Its Impact on Carbon Storage in Jiangsu Coastal, China

Coastal is the coupling of socio-economic and fragile ecosystems area existing development and protection problems, with lots of reserve land resources (i.e., bottomland and tidal flats). Analyzing and predicting the carbon storage changes caused by land use/land cover (LULC) on the Jiangsu coast were critical for revealing the potential problems of land surface changes and sustainable development. Then, we utilized the single dynamic degree and transfer in/out contribution, exploring the characteristics of LULC change in the study area from 1980 to 2018. Using the InVEST model, PLUS-LEAS model, and PLUS-Markov chain module, we assessed the spatiotemporal of the study area at the county level to reveal the LULC change strategy and driving factor contribution, as well as the composition of LULC and carbon storage in 2036. The results show that the LULC structure in the study area significantly changed from 1980 to 2018, in which the tidal flat and high coverage grassland decreased by 552.84 km2 and 383.71 km2 while the reservoir ponds and urban residential land increased by 1210.69 km2 and 101.70 km2. The major driving factor of LULC change has shifted from a single-factor to multi-factor coupling, and the influence contribution of human activity increased by 6.73%, especially the population. The carbon storage of study areas showed a significant decrease trend during 1980–2010, followed by a slight increase during 2010–2018. High-density carbon storage was mainly distributed in Lianyungang and Nantong and presented a decreasing trend along the coastline extending inland. The dry land and reservoir ponds are the main composition of LULC types in 2036, and the carbon storage increased to 2.39 × 108 t. In addition, more than decades of LULC change will cover part or all of the land use change process and trends, especially high-covered grasslands, so we suggest a 10-year LULC change to analyze coastal areas with lots of tidal flats and bottomlands. Therefore, this study can provide reference and theoretical guidance for ecologically sustainable development and future LULC evolution in coastal cities.

Thickness debit effect and multi-factor coupling mechanism of Ni3Al-based single crystal alloy

With the continuous development of aircraft engine generations, single-crystal alloy blades with more complex shapes and reduced wall thickness are urgently requested. However, the deteriorated performance associated with the wall thickness reduction has not been effectively resolved until now. In this research, the creep behavior of a [001]-oriented Ni3Al-based single crystal alloy with a thin-wall thickness was explored under the environment of 980 °C/220 MPa. A multi-factor coupling mechanism was proposed to explain the premature failure of the thin-walled specimen, providing a comprehensive understanding of the reasons behind the occurrence of the thickness debit effect. The study elucidated the influences of surface oxidation, the stress state of TCP phases, pore growth, and crack propagation on the creep performance. The findings serve as valuable theoretical references for the design and related research of future blade materials.

Investigation of surface textures deterioration on pavement skid-resistance using hysteresis friction models and numerical simulation method

Many rubber friction theories or some method combined theories and field-experiments are employed to evaluate the pavement skid-resistance deterioration due to the evolution of surface textures. However, these methods are difficult to be implemented in the analysis of situations with multi-factor coupling and some extreme conditions. This study developed a framework to evaluate the skid-resistance deterioration of asphalt pavements. In this framework, the portable laser scanning was used to create the digital worn pavement model, and a hydroplaning finite element (FE) model for these digital worn pavements was constructed to evaluate coupling effects of the texture evolution and factors of slip ratio, slip angle, velocity and water film on braking-cornering characteristics of tire. In this study, the deterioration of skid-resistance of five typical asphalt pavements due the surface texture wear was systematically investigated by this framework. Compared with previous works, this study established the rubber friction models for each digital worn pavement considering the energy hysteresis of rubber and the power spectrum density of surface texture. And the rubber friction model was used to define the interaction behaviors between the tire and corresponding wore pavements in the FE hydroplaning model, rather than using an empirical friction model or a fixed friction coefficient.

Sustainable management of water, nitrogen and biochar resources for soybean growth considering economic, environmental and resource use efficiency aspects: An integrated modeling approach

Intensive soybean production requires that water and fertilizer are collaboratively managed in an accurate and efficient manner, while biochar application offers a sustainable approach for protecting land, alleviating water scarcity, and increasing crop yield. The purpose of this study was to carry out a multifactor coupling orthogonal experiment of irrigation, nitrogen and biochar in the soybean growing season in 2021 and 2022 via plot treatment, linking the effect of irrigation and nitrogen on soybean yield with the carbon sequestration and emission reduction properties of biochar. A dynamic regulation model with multi-dimensional objective synergy for soybean yield, water footprint (WF), carbon footprint (CFP), water use efficiency (WUE) and partial productivity of nitrogen fertilizer (PFPN) based on the comprehensive regulation framework of experimental-simulation-optimization was constructed. This model was used to explore the optimal irrigation, nitrogen and biochar application patterns and their synergistic effects on yield and environmental benefits. The results showed that soybean yield and PFPN were affected by irrigation, nitrogen application affected WF and WUE, and biochar application affected CFP. Irrigation significantly affected the soil water content and consequently the WF while enhancing the crop yield and PFPN. Compared to the I1 treatment, the I0 treatment reduced water consumption, and the addition of nitrogen (N0 and N1) contributed to higher crop yields and WUE. The addition of biochar significantly increased crop yield, WUE and PFPN while mitigating the impact of nitrogen fertilizer application on greenhouse gas emissions. Based on the three-factor interaction, the yield, WF, CFP, WUE, and PFPN in 2022 increased by 3.03%, 3.51%, 2.17%, 1.59%, and 7.61%, respectively, compared to those in 2021. In addition, combined with water and nitrogen application, biochar application reduced CFP while increasing soybean yield, WUE and PFPN. A multiobjective optimization model demonstrated that when the amounts of irrigation, nitrogen, and biochar in 2021 and 2022 were 178.4 mm, 104.6 kg/hm2, and 8650.8 kg/hm2 and 153.7 mm, 93.7 kg/hm2, and 8063.4 kg/hm2, respectively, the synthetic degrees of yield, WF, CFP, WUE, and PFPN reached 0.866 and 0.872, respectively. The coordinated regulation of irrigation, nitrogen, and biochar reached a high-quality coordinated level that was 14.39% and 7.13% higher in 2021 and 2022 than the best I0N0B1 treatment, respectively. In this study, a combination of experiment-simulation-optimization is used to propose optimal irrigation, nitrogen and biochar regulation methods that synergize soybean yield, resource use efficiency and environmental benefits, which are of theoretical value for promoting green and efficient soybean production in black soil areas.

Intelligent design of limit states for recycled aggregate concrete filled steel tubular columns

The defects of RAC and confinement effect have a significant influence on the performance of RACFST. But traditional model based on linear regression are insufficient to evaluate this multi-factor coupling mechanism. This study proposed an intelligent prediction procedure for the limit state of RACFST (ultimate bearing capacity, peak strain and stress–strain model) based on machine learning. A database containing 176 circular and 126 rectangular RACFST samples was employed to assess the applicability of existing specification, and was then used to train 8 ML models. The ML predictive models showed higher accuracy than 6 existing equations in the specifications. The XGBoost model had the highest prediction accuracy (predicted/test values of ultimate bearing capacity was 1.0062/0.9981 for rectangular/circular, respectively). The underlying mechanisms of the design parameters on the ultimate bearing capacity of RACFST were revealed employing the SHapley Additive exPlanations. The design method of RACFST ultimate bearing capacity applicable to engineering design was derived by analyzing the key parameters, and the prediction results obtained from XGB model were used to improve the stress–strain model. The results show that the design procedure proposed in this study combines the ML models with the traditional physical model can effectively guide the intelligent design of RACFST.

Failure behaviour of EB-PVD YSZ thermal barrier coatings under simulated aero-engine operating conditions

Thermal shock test simulating aero-engine operating conditions was carried out on electron beam physical vapor deposition (EB-PVD) yttria partially stabilized zirconia (YSZ) thermal barrier coatings (TBCs) using advanced multi factor coupling test equipment. Phase composition, thermally grown oxide (TGO) residual stress, surface morphology and cross-sectional microstructure evolution in coatings were systematically studied. Based on XRD results, coatings possessed tetragonal phase structure without any further transformation during testing. After 5000 cycles, the thickness of TGO gradually increased from 0.3 to 2 μm. TGO residual compressive stress also gradually increased and then drastically dropped when the coating spalled. Horizontal cracks first initiated from TGO/bond coat (BC) interface, then arose from top coat (TC)/TGO interface and finally coalesced through TGO to cause delamination. Repeated thermal shock and gas impact conditions promoted the emergence of vertical cracks in ceramic top coat. Once communicated with transverse delaminations, cracks eventually led to spalling failure of the coating system. The contribution to spallation failure was mainly from thermal stress as a result of thermal expansion mismatch between the coating and the substrate. In turn, elastic stress induced by high speed impact of gas and TGO growth stress promoted initiation and propagation of coating cracks.