The adsorption of the bentonite toward Ni(II) from aqueous solution was studied to obtain optimum conditions, equilibrium model, thermodynamic and kinetic parameters. Statistical method was used to evaluate maximum amount of adsorbed Ni (II). In this work, pH of solution during stirring, contact time, initial Ni (II) concentration, particle size of bentonite and amount of bentonite were considered as effective parameters which should be examined. The increase of temperature has negative effect on the Ni(II) adsorption. The equilibrium data were correlated well with Freundlich and Dubinin–Radushkevich isotherm models the correlation coefficients of which are (R²) 0.994 and 0.971, respectively. This model indicates heterogeneous and chemical absorption or ion exchange process. The values of thermodynamic parameters such as ΔH°, ΔS° and ΔG° of nickel adsorption reveal that it is a spontaneous, exothermic and associative process. The experimental data fit the pseudo-second-order kinetic very well with correlation coefficient (R²) more than 0.995.

A process was proposed to convert and separate selenium and arsenic in copper anode slime (CAS) by low-temperature alkali fusion process. Central composite design was employed to optimize the effective parameters, in which NaOH/CAS mass ratio, fusion temperature and fusion time were selected as variables, and the conversion ratio of selenium and arsenic as responses. Second-order polynomial models of high significance and 3D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of >90% selenium conversion ratio and >90% arsenic conversion ratio was obtained by the overlaid contours at NaOH/CAS mass ratio of 0.65-0.75, fusion temperature of 803-823 K and fusion time of 20-30 min. The models are validated by experiments in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the fusion process.

A novel process was proposed for the utilization of potash feldspar by roasting in the presence of sodium carbonate. The effects of roasting temperature, granularity, molar ratio of sodium carbonate to potash feldspar and roasting time on the silica extraction rate were investigated. Under the optimal roasting conditions, the silica extraction rate was 98%. The optimal conditions, determined using an orthogonal experiment, were found to be roasting temperature of 875 °C, potash feldspar granularity of 74–89 μm, molar ratio of sodium carbonate to potash feldspar of 1.2:1, and roasting time of 80 min. The kinetics of potash feldspar roasting in the presence of sodium carbonate was described by the shrinking core model and the reaction rate was found to be controlled by the chemical reaction at the particle surface. According to the Arrhenius expression, the activation energy was 164.99 kJ/mol, and the process could be expressed as [1-(1-α)^1/3]=2.66×10⁵ exp[-164990/(RT)] t.

The alloying effects of V on structural, elastic and electronic properties of TiFe2 phase were investigated by the first-principles calculations based on the density functional theory. The calculated energy properties including cohesive energy and formation enthalpy indicate V atom would preferentially substitute on 6h sites of Fe atoms in the lattice of TiFe₂ to form the intermetallic Ti₄Fe₇(V). The calculated results of polycrystalline elastic parameters confirm that the plasticity of TiFe₂ would be improved with the addition of V. By discussing the percentage of elastic anisotropy, anisotropy in linear bulk modulus and directional dependence of elastic modulus, it is revealed that the anisotropy of TiFe₂ and Ti₄Fe₇(V) is small. Finally, the density of states, charge density distribution and Mulliken population for TiFe₂ and Ti₄Fe₇(V) were calculated, suggesting there is a mixed bonding with metallic, covalent and ionic nature in TiFe₂ and Ti₄Fe₇(V) compounds. These results also clarify that the reason for the improvement of plasticity with the addition of V in TiFe₂ is the weakened bonding of covalent feature between Ti and V atoms.

In order to improve the threading stability and the head thickness precision in tandem hot rolling process, an adaptive threading strategy was proposed. The proposed strategy was realized by the rolling characteristics analysis, and factors which affect the rolling force and the final thickness were determined and analyzed based on the influence coefficients calculation process. An objective function consisting of the influenced factors was founded, and the disturbance quantity was obtained by minimizing the function with the Nelder-Mead simplex method, and the proposed adaptive threading strategy was realized based on the calculation results. The adaptive threading strategy has been applied to one 7-stand hot tandem mill successfully, actual statistics data show that the predicted rolling force prediction in the range of ±5.0% is improved to 97.8%, the head thickness precision in the range of ±35 μm is improved to 98.5%, and the threading stability and the head thickness precision are enhanced to a high level.

Lonicera caerulea L. fruit is an excellent source of bioactive compounds. An efficient separation method of cyanins is important for the development of many value-added products and functional food ingredients. High-speed counter-current chromatography (HSCCC) was applied to isolate cyanins from Lonicera caerulea fruits with a biphasic solvent system composed of methyl tert-butyl ether/n-butanol/acetonitrile/water/trifluoroacetic acid (2:2:1:5:0.01, volume ratio). 1.41 mg of cyanidin 3, 5-O-diglucoside, 1.08 mg of cyanidin 3-O-rutinoside and 6.38 mg of cyanidin 3-O-glucoside were obtained from 40 mg of crude extract. The purities of these compounds were 95.8%, 92.4% and 97.6%, respectively, as identified by high-performance liquid chromatography–diode array detection (HPLC-DAD) and high-performance liquid chromatography-electrospray ionization mass spectrometryⁿ (HPLC-ESI/MSⁿ). In addition, the dominant anthocyanin, cyanidin 3-O-glucoside was demonstrated cytotoxic response of human hepatocarcinoma SMMC-7721 cells, inducing live cancer cell apoptotic by flow cytometric analysis.

Springback of a SUS321 complex geometry part formed by the multi-stage rigid-flexible compound process was studied through numerical simulations and laboratory experiments in this work. The sensitivity analysis was provided to have an insight in the effect of the evaluated process parameters. Furthermore, in order to minimize the springback problem, an accurate springback simulation model of the part was established and validated. The effects of the element size and timesteps on springback model were further investigated. Results indicate that the custom mesh size is beneficial for the springback simulation, and the four timesteps are found suited for the springback analysis for the complex geometry part. Finally, a strategy for reducing the springback by changing the geometry of the blank is proposed. The optimal blank geometry is obtained and used for manufacturing the part.

A method of system structural analysis based on decision making trial and evaluation laboratory together with interpretative structural modeling (DEMATEL-ISM) and entropy is proposed to clarify system structure of communication networks and analyze mutual influencing degree between different networks. Mutual influencing degree and importance degree of elements are both considered to determine weights of elements, and the entropy of expert judgment results is used to omit unimportant influence relation and simplify system structure. Structural analysis on communication networks system shows that the proposed method can quantificationally present weights and mutual influencing degree of elements, and reasonably simplify system structure. The results indicate the rationality and feasibility of the method.

The combined influence of nonlinearity and dilation on slope stability was evaluated using the upper-bound limit analysis theorem. The mechanism of slope collapse was analyzed by dividing it into arbitrary discrete soil blocks with the nonlinear Mohr–Coulomb failure criterion and nonassociated flow rule. The multipoint tangent (multi-tangent) technique was used to analyze the slope stability by linearizing the nonlinear failure criterion. A general expression for the slope safety factor was derived based on the virtual work principle and the strength reduction technique, and the global slope safety factor can be obtained by the optimization method of nonlinear sequential quadratic programming. The results show better agreement with previous research result when the nonlinear failure criterion reduces to a linear failure criterion or the non-associated flow rule reduces to an associated flow rule, which demonstrates the rationality of the presented method. Slope safety factors calculated by the multi-tangent inclined-slices technique were smaller than those obtained by the traditional single-tangent inclined-slices technique. The results show that the multi-tangent inclined-slices technique is a safe and effective method of slope stability limit analysis. The combined effect of nonlinearity and dilation on slope stability was analyzed, and the parameter analysis indicates that nonlinearity and dilation have significant influence on the result of slope stability analysis.

To assess the water inflow which is more suitable to the actual conditions of tunnel, an empirical correlation about the permeability coefficient changing with depth is introduced. Supposing that the surrounding rock is heterogeneous isotropy, the formula for calculating water inflow of tunnel with the nonlinear variation of permeability coefficient is deduced. By the contrast analysis with the existing formulas, the presented method has the similar value to them; moreover, the presented method has more simple form and easy to use. Due to parameter analysis, the water inflow decreases after considering the nonlinear variation of permeability coefficient. When the attenuation coefficient a>0, the water inflow increases first till reaches the maximum at a certain depth, then decreases and is close to 0 finally if deep enough. Thus, it is better to keep away from the certain depth where it is with the maximum water inflow for safe operation and economical construction, and reduce the water damage. Based on the analysis, the radius of tunnel has less impact on the amount of water inflow, and the water inflow just increases by 6.7% when the radius of tunnel increases by 1 m.

Strength of discontinuities with complex structure is an important topic in rock engineering. A large number of studies have shown that fractal is applicable in the description of this discontinuity. Using fractal interpolation method for the generation of rock joints, numerical experiments of shear tests of the jointed rock mass model were carried out using FLAC^3D. The test results show that the real rock joints can be simulated by fractal curves obtained by fractal interpolation. The fractal dimension is an important factor for the characterization of jointed rock mass; test results show that the fractal dimension of rock joints can be related to the equivalent cohesion strength and shear strength of the rock mass. When the fractal dimension of the joint surface is less than critical dimension D_c 1.404, the cohesion strength and shear strength of the rock mass increase as the fractal dimension increases; for larger fractal dimensions, all mechanical parameters decrease as the fractal dimension increases. Joint surfaces with different degrees of roughness were obtained by the fractal interpolation method. Three types of failure modes were observed in the tests: climbing slip failure, climbing gnawing fracture, and non-climbing gnawing fracture.

Major and REE geochemistry and multi-fractal analysis of two types of bauxite (primary bauxite and accumulated bauxite) ores were studied in Pingguo bauxite orefield in western Guangxi, China. The results of geochemical data show that the accumulated bauxite has a feature of high Al₂O₃ whereas relative low Fe₂O₃ and SiO₂ contents compared to the primary bauxite. The similar chondrite-normalized rare earth element (REE) patterns illustrate that they have a cognate relationship. However, the negative Ce anomalies of primary bauxite and positive Ce anomalies of accumulated bauxite indicate that the ore-forming system changed from reducing environment to oxidation environment. The results of multi-fractal spectrum and parameters of Al₂O₃, Fe₂O₃ and SiO₂ between primary bauxite and accumulated bauxite show that the distinct multi-fractal spectrum parameters reflect the different grade distribution between accumulated and primary bauxite ores. Metallogenic process from primary bauxite to accumulated bauxite is accompanied by the loss of diffluent elements (e.g., Si and S) and enrichment of stable elements (e.g., Al and Fe) in the surface environment. Among the rest, the migration mechanism of iron during the evolutionary process from primary ore to accumulated ore can be described as combined leaching and chemical weathering action with participation of sulfur.

Backfill hydraulic support is the key equipment in achieving coal mining and solid backfilling simultaneously in solid backfill mining technology. Based on the summary and analysis of main types, basic structural properties and filed application of backfill hydraulic support, this work has firstly proposed the basic principle of backfill hydraulic support optimization design and provided the method of optimal design of key structural components, like four-bar linkage, rear canopy and tamping structure; the method is further elaborated as changing hinging position of upper bar to optimize four-bar linkage, by lengthening or shortening the rear canopy to optimize length ratio of canopy; and by changing length and hinging position of tamping structure as well as suspension height of backfill scrape conveyor to realize optimization of tamping structure. On this basis, the process of optimal design of backfill hydraulic support is built. The optimal design case of ZC5200/14.5/30 six columns-four bar linkage used in 7203W workface of Zhaizhen Coal Mine shows that the backfill properties like horizontal roof gap, vertical horizontal gap, tamping angle and tamping head gap are improved obviously through optimizing four-bar linkage, canopy length and tamping structure according to the optimal design method proposed in this work.

Brazilian disc tests were undertaken on a number of red sandstone samples with different water absorption ratios. The tensile strength of the red sandstone decreases as the water absorption ratio increases. The fracture surfaces of failed red sandstone discs were scanned by Talysurf CLI 2000. With the aid of Talymap Gold software, based on ISO25178, a set of statistical parameters was obtained for the fracture surfaces. The maximum peak height (S_p), maximum pit height (S_v) and maximum height (S_z) of the fracture surfaces exhibited the same decreasing trend with increasing water absorption. S_a and S_ku values for the fracture surfaces showed a downward trend as the water absorption ratio increased. The fractal dimensions of fracture surfaces were calculated and found to decrease as the water absorption ratio increased. Through analysis of PSD curves, the smallest dominant wavelength was observed to reflect the roughness of the fracture surfaces. Additionally, the results suggest that the roughness of fracture surfaces becomes small as the water absorption ratio increases.

In this investigation, we have studied the peristaltic fluid flow in an asymmetric channel with convective walls. Fourth grade fluid model has been utilized in view of the fact that the results of all other differential type models can be deduced as the special case. Combined effects of heat and mass transfer are considered. The thermophoresis effects occur in the energy equation. Convective heat and mass boundary conditions have been given special attention. Long wave length and low Reynolds number approximations are utilized for the simplifications. Approximate analytic solutions for the velocity, temperature and concentration profiles are calculated using perturbation technique and elaborated in the form of graphical observations for various physical quantities.

The nature of the exergy consumption of district heating (DH) systems can not be explained clearly using the first law of thermodynamics. Exergy analysis method was used. A case study based on a DH system in Inner Mongolia, China, was carried out. The impact of operating parameters and design parameters on the energy quality of circulating water and exergy losses of DH systems during heat distribution was revealed. Results show that the energy quality of circulating water and exergy losses of DH systems during heat distribution could be reduced by decreasing the indoor temperature or increasing radiator areas. Compared with other factors, the outdoor temperature and indoor temperature have a greater impact on the energy quality of circulating water, exergy losses of circulating water, and total exergy losses during heat distribution. When the outdoor temperature varied by 10.00%, the average variation rates of such parameters were 85.12%, 90.02%, and 64.60%, respectively. When the outdoor temperature was 273.00 K and indoor temperature varied by 50.00%, the average variation rates of such parameters were 83.88%, 99.34% and 32.87%, respectively. It can be observed that the energy quality and exergy losses of DH systems can be reduced in the operation process.

Compression ratio is significant for cellular structures on energy absorption. In the present work, theoretical formulas to determine the initial densification strain of honeycomb structure were put forward by means of minimum energy principle. Detailed densification strain points were identified, with full fold model for kinds of specimens. To validate, corresponding numerical simulations were carried out with explicit finite element method. Excellent agreement in terms of initial densification stain point has been observed between the theoretical calculation and numerical simulation. The results show that: ① different honeycomb structure has different initial densification strain point, and its geometric configuration of cells plays an evident role on densification; ② half-wave length of the wrinkle of honeycomb in folding process significantly influences on the densification strain point; ③ the initial densification point is an decreasing power function of the ratio of foil thickness to cell length, with the exponent 2/3. These achievements provide important references for design in cellular energy absorption devices.

The characteristics of a disturbed soil-structure interface were studied based on the variation regularities of the disturbed soil within its mining subsidence area using direct shear tests. The effects of the initial moisture content on the shear strength parameters of the soil-structure interfaces were analyzed. The results indicate that the cohesion of the interface initially increased and then decreased as the initial moisture content increased. In addition, the friction angle of the interface decreased as the initial moisture content increased. A constitutive model of the disturbed soil-structure interface, a rigid-plastic model based on the initial void ratio and saturability (VSRP) model, was established based on the results. In order to validate this model, a finite element analysis of DRS-1 direct shear tests was conducted. The finite element model calculations coincided with the results of the DRS-1 direct shear tests. The proposed model also reflected the nonlinear features of the soil-structure interface.

Soft and medium-hard rocks are subjected to high rheology under high stress, and they are prone to a relatively large-degree of deformation when perturbed by external impacting loads. The phenomenon where rock deformation is developed due to external impacting perturbation in the rheological state is defined as the rock rheological perturbation effect. This work presents a new experimental system for investigating the rock rheological perturbation effect with experiments on medium-hard red sandstone. Results from our analysis show that red sandstone changes under two mechanical mechanisms: deformation-hardening effects at low stress states, and damage-fracture effects at high stress states when impacted by certain external impacting loads. Red sandstone tested in our experiments has a strain threshold of about 90% of the ultimate strain under the perturbation effect; the red sandstone is sensitive to a perturbed load when its actual strain exceeds the threshold. The perturbed deformation process of the rock can be divided into three phases: decline, approximately constant speed and acceleration. The rock will be rapidly destroyed when the perturbed deformation accumulates to a certain degree. The perturbation effect of rock deformation under uniaxial compression is more obvious than that under axial compression. Based on our experiment, a constitutive relation of the rock rheological perturbation effect is developed.

Direct dynamics simulations are a useful and general approach for studying the atomistic properties of complex chemical systems because they do not require fitting an analytic potential energy function. Hessian-based predictor-corrector integrators are a widely used approach for calculating the trajectories of moving atoms in direct dynamics simulations. We employ a monodromy matrix to propose a tool for evaluating the accuracy of integrators in the trajectory calculation. We choose a general velocity Verlet as a different object. We also simulate molecular with hydrogen(CO₂) and molecular with hydrogen (H₂O) motions. Comparing the eigenvalues of monodromy matrix, many simulations show that Hessian-based predictor-corrector integrators perform well for Hessian updates and non-Hessian updates. Hessian-based predictor-corrector integrator with Hessian update has a strong performance in the H₂O simulations. Hessian-based predictor-corrector integrator with Hessian update has a strong performance when the integrating step of the velocity Verlet approach is tripled for the predicting step. In the CO₂ simulations, a strong performance occurs when the integrating step is a multiple of five.