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This study presents a thermodynamic equilibrium analysis of hydrogen-rich syngas production via biomass–methane co-pyrolysis, employing the Gibbs free energy minimization method. A critical temperature threshold at 700 °C is identified, below which methanation and carbon deposition are thermodynamically favored, and above which cracking and reforming reactions dominate, enabling high-purity syngas generation. Methane addition shifts the reaction pathway towards increased reduction, significantly enhancing carbon and H2 yields while limiting CO and CO2 emissions. At 1200 °C and a 1:1 methane-to-biomass ratio, cellulose produces 50.84 mol C/kg, 119.69 mol H2/kg, and 30.65 mol CO/kg; lignin yields 78.16 mol C/kg, 117.69 mol H2/kg, and 19.14 mol CO/kg. The H2/CO ratio rises to 3.90 for cellulose and 6.15 for lignin, with energy contents reaching 43.16 MJ/kg and 52.91 MJ/kg, respectively. Notably, biomass enhances methane conversion from 25% to over 53% while sustaining a 67% H2 selectivity. These findings demonstrate that syngas composition and energy content can be precisely controlled via methane co-feeding ratio and temperature, offering a promising approach for sustainable, tunable syngas production.

Highly crystalline and small-diameter boron nitride nanotubes (BNNTs) are synthesized using a triple DC thermal plasma jet with continuous injection of boron feedstock at atmospheric pressure. The reaction pathway to BN phase is analyzed with thermodynamic equilibrium analysis. It is founded that BN formation through a reaction between nitrogen ion and boron is more thermodynamically favorable than recombination of nitrogen ion with electron. Nitrogen ions formed in the strong electric field of the plasma torches actively react with the boron feedstock, resulted in the formation of BN phase. As a result, the high production rate for BNNTs approaching at 22 g/h is achieved. Input power and total gas flow rate about production rate are 3.4 MJ/g and 120 L/g, resulting in the energy cost superior to those reported to date. Consequently, these findings suggest the industrial-scale production of BNNTs through an atmospheric pressure DC thermal plasma reactor. Graphical abstract

A unified formulation is presented for non-linear time history, static pushover and limit analysis of historic masonry structures modelled as 2D assemblages of rigid blocks interacting at no-tension, frictional contact interfaces. The dynamic, incremental static and limit analysis problems are formulated as mathematical programming problems which are equivalent to the equations system governing equilibrium, kinematics and contact failure. Available algorithms from the field of mathematical programming, contact dynamics and limit analysis are used to tackle the contact problems between rigid blocks in a unified framework. To evaluate the accuracy and computational efficiency of the implemented formulation, applications to numerical case studies from the literature are presented. The case studies comprise rigid blocks under earthquake excitation, varying lateral static loads and sliding motion. A set of two leaves wall panels and an arch-pillars system are also analysed to compare failure mechanisms, displacement capacity and magnitudes of lateral loads promoting the collapse.

Both the limit analysis and the limit equilibrium approach require the formulation of a failure criterion in terms of components of stress vector acting on a potential failure plane. For applications in Rock Mechanics, the generalized Hoek–Brown (GHB) criterion is commonly used, for which no analytical form of the Mohr failure envelope is, in general, available. In this work, a new approximation of the Mohr envelope for the GHB criterion is developed, which is valid in a broad range of GSI (i.e. Geological Strength Index) values. The approach is based on the orthogonal projection of a function for best-fitting the quadratic or cubic polynomials to the Balmer’s equations that define the relationship between the normal stress acting on the failure plane and the minor principal stress. The methodology is illustrated by a limit equilibrium analysis, which involves assessment of the safety factor of a rock slope that has a vertical tension crack embedded in the upper horizontal surface. The analysis employs an approximate Mohr envelope based on the cubic polynomial fitting as the failure condition along the rupture surface. The results indicate that the safety factor for stability of the slope is very sensitive to the geometry of the crack (i.e. its location and depth) as well as the selection of the value of GSI.

Soil nailing as a construction practice has turned into a prime earth retention and slope stabilization technique. Present study undertakes potential parametric optimization in soil nailing by considering soil nail interaction and back analysis of the pull-out strength of nail using Finite Element Analysis using PLAXIS 2D. Results suggested pull-out strength as a function of depth, thereby providing a potential scope for optimization of soil nail length pattern. The observed trend of results has been further validated using Limit Equilibrium Analysis. Further, dynamic analysis was undertaken to ensure the seismic stability considering the reduced nail length pattern using FHWA guidelines and the numerical approaches like finite element and limit equilibrium methods. Results suggest that the observed trend with reduced nail length patterns caused mild increment in the serviceability conditions like horizontal deformation, but the results were observed to be within permissible limits in the ultimate limit state. Furtherance to the numerical analyses, a numerical regression analysis was undertaken to develop a correlation between the geotechnical parameters, nail length patterns and the limit conditions.

This study aims to propose state-of-the-art techniques in predicting and controlling slope stability in open-pit mines based on limit equilibrium analysis, artificial neural networks, and optimization algorithms. Accordingly, the simplified Bishop method was used to analyze the slope stability of an open-pit coal mine through the limit equilibrium analysis method. Various rock mass properties and the geometrical parameters of the slopes were considered, such as bench height, slope angle, unit weight, cohesion, and friction angle. Finally, 495 cases were analyzed to compute the factor of safety (FOS). Subsequently, the radial basis function neural network (RBFNN) model was applied to predict FOS. In order to optimize the RBFNN model, the brainstorm optimization (BSO) algorithm was applied to train the RBFNN model, named as BSO-RBFNN model. The genetic algorithm (GA)-RBFNN, RBFNN (without optimization), and multiple layers perceptron (MLP) neural network were also developed to predict FOS and compared with the proposed BSO-RBFNN model as part of the study. The results revealed that the optimization of the BSO algorithm and RBFNN model provided a state-of-the-art technique (i.e., BSO-RBFNN) for predicting and controlling slope stability with high accuracy (i.e., mean absolute error (MAE) = 0.047, root-mean-squared error (RMSE) = 0.057, determination coefficient (R2) = 0.929, variance accounted for (VAF) = 92.948), and reliability (i.e., absolute error of 5.89% for 80% of cases in practice). Comparisons also indicated that the proposed BSO-RBFNN model is the most dominant model for predicting slope stability in this study (i.e., MAEGA-RBFNN = 0.048, RMSEGA-RBFNN = 0.060, R2GA-RBFNN = 0.927, VAFGA-RBFNN = 92.534; MAERBFNN = 0.064, RMSERBFNN = 0.081, R2RBFNN = 0.925, VAFRBFNN = 89.189; MAEMLP = 0.065, RMSEMLP = 0.081, R2MLP = 0.873, VAFMLP = 85.724). Furthermore, the slope angle and bench height should be taken into account to control slope stability in practical engineering based on the proposed BSO-RBFNN model.

The formation of slagging and fouling during municipal solid waste (MSW) incineration not only significantly affects heat transfer, but also results in shortened operating cycles. In order to solve the issues, the effect of different additives on the migration and transformation patterns of alkali/alkaline earth metals (AAEM) and chlorine during MSW incineration is screened based on the Gibbs energy minimization method. The effect of potential additives on the ash fusion temperature and combustion reactivity of MSW char is subsequently verified and evaluated by experimental methods. The thermodynamic equilibrium analysis shows that Al(NO3)3, Ca(NO3)2, and Mg(NO3)2 have great potential to increase the ash fusion temperature. The experimental investigation confirms that the addition of Al(NO3)3, Ca(NO3)2, and Mg(NO3)2 significantly increases the ash fusion temperature. The order of increasing the ash fusion temperature by different additives is Mg(NO3)2 > Ca(NO3)2 > Al(NO3)3. The addition of Mg(NO3)2 significantly increased the initial deformation temperature, softening temperature, hemispheric temperature, and flow temperature of ash from 1180, 1190, 1200, and 1240 °C to 1220, 1230, 1240, and 1260 °C, respectively. The addition of Cu(NO3)2, Fe(NO3)3, and KMnO4 significantly decreases the temperature at the maximum weight loss rate of MSW char, while increasing the maximum weight loss rate. Additionally, Cu(NO3)2 shows the best performance in improving the combustion reactivity of MSW char. The addition of Cu(NO3)2 evidently increases the maximum weight loss rate from 0.49 to 0.54% °C−1. Therefore, it is concluded that Mg(NO3)2 and Cu(NO3)2 are supposed to be the most potential candidates for efficient additives. This study presents an efficient and economical method to screen potential additives for alleviating slagging and fouling during MSW incineration.

Previous research has demonstrated that concave cross-sectional geometry can enhance slope stability, reduce sediment loss, and improve mining efficiency. However, studies on the use of concave facing in geosynthetic-reinforced soil (GRS) walls are limited. This study idealizes the concave facing as a circular arc whose concavity is determined by the wall height, batter and mid-chord offset. Based on the limit equilibrium analysis, a modified top-down procedure is proposed to investigate the impact of concave facing on the internal stability of GRS walls. Using the presented method, the distribution of required tension along the reinforcement layer and necessary connection load can obtain while considering the pullout capacity at a given layout and factor of safety. Sensitivity analysis, including the mid-chord offset, wall batter, reinforcement length, vertical spacing, and facing blocks, are carried out to explore the impacts of facing profile concavity on the internal stability of GRS walls. Results show that concave facing can significantly reduce the required tension along the reinforcement, and the required connection strength is sensitive to the variation in the facing profile. Increasing the wall batter can result in a greater reduction of maximum required tension for the concave wall, but it can also increase the connection load for most reinforcements. The concavity of the facing has no effect on the optimal reinforcement length, which is found to be 0.7 times the wall height. The differences in maximum required tension for various facing concavities gradually diminish when considering the toe resistance.

Carbon-based import tariffs are proposed as a policy measure to reduce carbon leakage and increase the global cost-effectiveness of unilateral CO2 emission pricing. We investigate the case for carbon tariffs. For our assessment, we combine multi-region input–output and computable general equilibrium analyses based on data from the World Input–Output Database for the period 2000–2014. The multi-region input–output analysis confirms that carbon embodied in trade has increased during this period, but trade flows from Non-OECD to OECD countries became less important in relative terms since the 2007–2008 financial crisis. The computable general equilibrium analysis suggests that carbon tariffs’ efficacy in combating leakage increases in periods when trade in carbon increases. However, its potential to improve the global-cost effectiveness of unilateral emission pricing remains modest. On the other hand, we find that the potential of carbon tariffs to shift the economic burden of CO2 emission reduction from abating developed regions to non-abating developing regions increases sharply between 2000 and 2007, but declines after the financial crisis.

Slope failures along road cuts and highways, occurring due to heavy rainfalls or earthquakes, pose significant threats to people, vehicles, and emergency plans. In the present study, a methodology to assess the stability of rock slopes at a regional scale is proposed using a kinematic analysis and a probabilistic limit equilibrium analysis for plane sliding and wedge failure modes. The workflow adopted is described through its implementation along the main road network of the island of Thasos, located in northern Greece. On-site investigations and measurements along the island’s road network formed the basis of the present study. The results of the kinematic analysis showed that the joint sets, which were identified during the on-site investigations, formed critical intersections that could lead to wedge and plane sliding failures. The on-site measurements and the results of the kinematic analysis were utilized to perform limit equilibrium back-analyses at sites of identified failures due to the water pressure effects to probabilistically estimate the material strength properties of the joints. Subsequently, numerous limit equilibrium analyses were executed within a Monte Carlo simulation framework to produce representative fragility curves of rock slopes against plane sliding and wedge failures along the main road network, due to earthquake loading and water pressures.