This paper presents a novel computational procedure for the maximum dry density of mixed soils containing oversize particles. At first, the large-scale compaction test data for mixed soils are analyzed by an artificial neural network to determine the main factors affecting the compaction. These factors are then imposed on a genetic programming method and a new mathematical equation emerges. The new equation has more conformity with the experimental data in comparison with the previous correction methods. Besides, the mixed soil dry density is associated with most base soil and oversize fraction specifications. With regard to the sensitivity analyses, if the mixed soil contains high percentages of oversize fraction, the mixed soil composition is governed by the specification of oversized grains, such as specific gravity and the maximum grain size and by increasing these factors, the mixed soil dry density is increased. In mixed soil with a low content of oversize, the base soil specification mainly controls the compaction behavior of mixed soil. Furthermore, if the base soil is inherently compacted with greater dry density, adding the oversize slightly improves the mixed soil dry density. In contrast, adding oversized grains to the base soil with a lower dry density produces a mixed soil with greater dry density. By increasing the maximum grain size difference between the oversize fraction and base soil, the dry density of mixed soil is enhanced.
The chemical, physical, thermal and texture properties of iron ores from different regions of Odisha and Chhattisgarh regions, India, have been investigated to understand the compositional variations of Fe, Al2O3, SiO2, S and P. They were analyzed for its susceptibility to meet the industrial requirements, for various iron manufacture techniques. Chemical analysis indicated that the majority of the iron ores is rich in hematite (> 90 wt%), poor in gangue (<4.09 wt% SiO2 and <3.8 wt% Al2O3) and deleterious elements (P<0.065 wt% and S<0.016 wt%) in all these iron ores found to be low. XRD peaks reviled that the gangue is in the form of kaolinite and quartz, and same was observed in Fourier transform infrared (FTIR) spectroscopy in the range of 914 to 1034 cm–1. The iron ores were found to have excellent physical properties exemplify with tumbler index (82 wt%–91 wt%), abrasion index (1.27wt%–4.87 wt%) and shatter index (0.87wt%–1.64 wt%). FTIR and thermal analysis were performed to assimilate the analysis interpolations. It was found that these iron ores exhibit three endothermic reactions, which are dehydration below 447 K with mass loss of 0.13 wt% to 1.7 wt%, dehydroxylation at 525–609 K with mass loss of 1.09 wt%–4.49 wt% and decomposition of aluminosilicates at 597–850 K with mass loss of 0.13 wt%–1.15 wt%. From this study, we can conclude that due to its excellent physico-chemical characteristics, these iron ores are suitable for BF and DRI operations.
The determination of material formula needs try-and-error experiment, and consumes large amount of time and fund. In order to solve the problem, a comprehensive method is established, via the experiment of artificial-similar material formula of a mine slope. We controlled the samples by the compactness, and arranged the formula of the test group with the method of the uniform formula experiment. The physical and mechanical parameters of these samples were analyzed using the method of the partial least-squares regression (PLS). And a mathematical model of the indexes of physical and mechanics parameters relating to the factors of formulation constituents was established eventually. We used the model to analyze the effect of each formulation constituent on physical and mechanics parameters of samples. The experiment results and analysis illustrates that 1) in the formulation of similar material, the effect of raw materials on the internal friction angle φ and cohesion C is opposite; 2) The method can highly facilitate the process of the of preparing artificial-similar materials, more economic and effective.
The mathematical and simulation models of working head in the deep-sea working environment were built to analyze the effects of cutter-suction flow, cutter-head rotating speed, cutting depth and suction port position on the cutter-suction capacity. The efficiency of the cutter-suction is analyzed based on the analysis of the variation law of the solid-phase volume fraction of the flow field, the variation law of the velocity distribution in the flow field and the distribution law of the solid-phase concentration. The results show that the increase of cutter-suction flow can significantly improve the cutter-suction efficiency when it is less than 1000 m3/h. However, when it is more than 1000 m3/h, it is helpless. When the cutter-head rotate speed is within the range of 10–25 r/min, the cutter-suction efficiency stabilizes at about 95%. While the speed is greater than 25 r/min, the cutter-suction efficiency decreases sharply with the increase of cutter-head rotate speed. With the increase of cutting depth, the cutter-suction efficiency first increases and then remains stable and finally decreases. The cutter-suction efficiency remains at about 94% when the suction port position deviation ranges from 0° to 30°, but it has a sharply reduction when the deviation angle is more than 30°.
A two-step information extraction method is presented to capture the specific index-related information more accurately. In the first step, the overall process variables are separated into two sets based on Pearson correlation coefficient. One is process variables strongly related to the specific index and the other is process variables weakly related to the specific index. Through performing principal component analysis (PCA) on the two sets, the directions of latent variables have changed. In other words, the correlation between latent variables in the set with strong correlation and the specific index may become weaker. Meanwhile, the correlation between latent variables in the set with weak correlation and the specific index may be enhanced. In the second step, the two sets are further divided into a subset strongly related to the specific index and a subset weakly related to the specific index from the perspective of latent variables using Pearson correlation coefficient, respectively. Two subsets strongly related to the specific index form a new subspace related to the specific index. Then, a hybrid monitoring strategy based on predicted specific index using partial least squares (PLS) and T2 statistics-based method is proposed for specific index-related process monitoring using comprehensive information. Predicted specific index reflects real-time information for the specific index. T2 statistics are used to monitor specific index-related information. Finally, the proposed method is applied to Tennessee Eastman (TE). The results indicate the effectiveness of the proposed method.
In the South Yellow Sea Basin, Mesozoic–Paleozoic marine strata are generally well developed with large thickness, and no substantial breakthroughs have been made in hydrocarbon exploration. Through research, it is believed that the Upper Permian–Lower Triassic can be regarded as a long-term base-level cycle. Based on drilling data, characteristics of the lithology–electric property combination cyclicity, and the special lithology, the long-term base-level cycle was divided into five medium-term base-level cycles (MC1–MC5). On this basis, the Permian–Triassic sedimentary systems and their filling model were analyzed in accordance with the change of base-level cycle and transition of sedimentary environment, as well as characteristics of the drilling sedimentary facies and seismic facies. The results show that there were six sedimentary systems (fluvial, delta, tidal flat, open platform, restricted platform, and continental shelf) developed in the Upper Permian–Lower Triassic, the sedimentary systems were distributed such that the water was deep in the northwest and shallow in the southeast, and there were two base-level cycle filling models (a relatively stable tidal flat facies and a rapidly transgressive continental shelf facies to stable platform facies) developed in the Upper Permian–Lower Triassic. These models can provide a basis for evaluation of the Mesozoic–Paleozoic hydrocarbon geology in the South Yellow Sea Basin.
Based on a new perspective of industry chain and selecting monthly data from February 2006 to December 2015, this paper chooses eight Chinese industrial sectors to construct a SVAR model reflecting internal relationships among metal chains, analyzes the direct effects and indirect effects of international metal prices on output of various links in metal chains, then it investigates the main transmission path of international metal price shocks through decomposing the inflation pressure sources in metal chains. The results show that international metal price shocks not only affect industrial output in a direct way, but also indirectly affect the growth of output through the increased pressure on industrial inflation and then triggering a tightening of monetary policy implementation. Affected by factors such as the lack of market demand and the price transmission mechanism blocking, the direct effects of international metal price shocks mainly impact the upstream and midstream industry, while the downstream industry is mainly affected by indirect effects; in addition, the international metal price shocks have spillover effects on the industrial inflation, and transmit along the industry chain from upstream to downstream, and their strength weakens in sequence.
Frac-packing technology has been introduced to improve the development effect of weakly consolidated sandstone. It has double effects on increasing production and sand control. However, determining operation parameters of frac-packing is the key factor due to the particularity of weakly consolidated sandstone. In order to study the mechanisms of hydraulic fracture propagation and reveal the effect of fracturing parameters on fracture morphology in weakly consolidated sandstone, finite element numerical model of fluid-solid coupling is established to carry out numerical simulation to analyze influences of mechanical characteristics, formation permeability, fracturing fluid injection rate and viscosity on fracture propagation. The result shows that lower elastic modulus is favorable for inducing short and wide fractures and controls the fracture length while Poisson ratio has almost no effect. Large injection rate and high viscosity of fracturing fluid are advantageous to fracture initiation and propagation. Suitable fractures are produced when the injection rate is approximate to 3–4 m3/min and fluid viscosity is over 100 mPa·s. The leak-off of fracturing fluid to formation is rising with the increase of formation permeability, which is adverse to fracture propagation. The work provides theoretical reference to determine the construction parameters for the frac-packing design in weakly consolidated reservoirs.
A process of removing impurities, such as Fe, Zr, Ti, Al, Si, from scandium solution by ion exchange was proposed. Various resins’ selectivity was studied in scandium chloride solution. The results indicated that D851 resin had high selectivity of Sc at low acidity, and high selectivity of Zr at high acidity; D370 resin had high selectivity of Fe and Si in high acidity. A new technical process of removing impurities from scandium chloride solution was proposed, which includes D370 resin adsorbing Fe in high acidity, D851 resin adsorbing Zr in medium acidity and D851 resin adsorbing Sc at low acidity. Flow experimental results show that removal rates of Al, Ca, Fe, Zr, Ti and Si, were 100%, 99.6%, 100%, 100%, 99.5% and 100% respectively.
A novel surface cladding technique was developed to prepare the FeCrNiMn alloy and high carbon steel cladding layers, and the microhardness, bonding strength, abrasion wear and corrosion resistance were investigated. The microstructures of the cladding layers were analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). The results show that the bonding strength between the substrate and the two cladding layers were (432.6±21) and (438.3±12) MPa,respectively. Vickers hardness values of the two cladding layers were HV 418.5 and HV 329.6, respectively. The corrosion current densities of the two coatings were 2.926×10–6 and 6.858×10–6 A/cm2 after electrochemical corrosion test in 3.5% NaCl solution, and the wear rate were 1.78×10–7 and 1.46×10–6 mm3/mN after sliding wear test, respectively. This indicates that a well metallurgical bonding between the coating and the substrate was achieved, the abrasion wear and corrosion resistance of both coatings had been greatly improved compared with the substrate. The novel cladding technology is promising for preparing wear-and-corrosion resistant coatings.
In order to improve the scheelite flotation with sodium oleate (NaOL), the effect of a non-ionic polyoxyethylene ether (JFC-5) on the floatability of scheelite was investigated through flotation experiments at 10 °C, compared with 60 mg/L NaOL alone, the recovery of scheelite is improved from 22% to 85% in the presence of JFC-5 with a mass ratio of 20% at pH 10. Moreover, the resistance to Ca2+ of NaOL is increased. The adsorption mechanism was analyzed by zeta potential measurement, contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis. The results show that the adsorption of NaOL on scheelite surface is enhanced after adding JFC-5 due to the more negative zeta potentials and larger contact angles of scheelite. And the co-adsorption of NaOL and JFC-5 is confirmed by XPS analysis, so it is indicated that the adsorption of JFC-5 decreases the electrostatic repulsion between the oleate ions, resulting in the stronger adsorption of NaOL on scheelite surface. In short, the mixed NaOL/JFC-5 collector can effectively improve scheelite flotation.
Geotechnical properties of red shale encountered in deep underground mining were characterized on both laboratory and field scale to reveal its unfavorably in geoenvironment. Its constituents, microstructure, strength properties and water-weakening properties were investigated. In situ stress environment and mining-induced fractured damage zone after excavation were studied to reveal the instability mechanism. The results show that red shale contains swelling and loose clayey minerals as interstitial filling material, producing low shear strength of microstructure and making it vulnerable to water. Macroscopically, a U-shaped curve of uniaxial compressive strength (UCS) exists with the increase of the angle between macro weakness plane and the horizon. However, its tensile strength reduced monotonically with this angle. While immersed in water for 72 h, its UCS reduced by 91.9% comparing to the natural state. Field sonic tests reveal that an asymmetrical geometrical profile of fractured damage zone of gateroad was identified due to geological bedding plane and detailed gateroad layout with regards to the direction of major principle stress. Therefore, red shale is a kind of engineering soft rock. For ground control in underground mining or similar applications, water inflow within several hours of excavation must strictly be prevented and energy adsorbing rock bolt is recommended, especially in large deformation part of gateroad.
Waste cellulosic biomass obtains various applications due to low-cost and eco-benign characteristics. A general strategy is proposed for waste cellulosic biomass to be modified with dialdehyde functional groups as intermediates through periodate partial oxidation. Finally, aminothiourea-modified waste cellulosic biomass can be prepared through Schiff reaction. Waste corn stalk, cotton and paper as typical precursors, were used to prepare cellulosic biomass, abbreviated as AT-S, AT-C and AT-P, respectively, and their adsorption behaviors of Au(III) from the hydrochloric acid medium were investigated. The pseudo-second kinetics equation as well as the Langmuir isotherm equation can be used to depict the adsorption process, and the maximum adsorption capacities of Au(III) are 21.4, 19.0 and 3.28 mol/kg for AT-S, AT-C and AT-P at 298 K, respectively. The adsorption capacities of Au(III) on aminothiourea modified corn stalk (AT-S) is almost 357 times greater than that of raw corn stalk. To the best of our knowledge, AT-S has the highest adsorption capacity towards Au(III). AT-S also displays a superior separation selectivity towards Au(III) in the presence of Cu(II), Ni(II), Co(II), Pt(VI), Pd(II) and Rh(III). Furthermore, the characterization analysis of XRD, TG, SEM, TEM and FTIR confirms that AuCl4– has been reduced to elemental Au nanoparticles and deposit onto the surface of the biomass. It shows a prospect for waste corn stalk to be used to adsorb Au(III) from liquid phase and the possible fabrication of gold nanoparticles by a general adsorption process without any reductant.
A new modified LuGre friction model is presented for electromagnetic valve actuator system. The modification to the traditional LuGre friction model is made by adding an acceleration-dependent part and a nonlinear continuous switch function. The proposed new friction model solves the implementation problems with the traditional LuGre model at high speeds. An improved artificial fish swarm algorithm (IAFSA) method which combines the chaotic search and Gauss mutation operator into traditional artificial fish swarm algorithm is used to identify the parameters in the proposed modified LuGre friction model. The steady state response experiments and dynamic friction experiments are implemented to validate the effectiveness of IAFSA algorithm. The comparisons between the measured dynamic friction forces and the ones simulated with the established mathematic friction model at different frequencies and magnitudes demonstrate that the proposed modified LuGre friction model can give accurate simulation about the dynamic friction characteristics existing in the electromagnetic valve actuator system. The presented modelling and parameter identification methods are applicable for many other high-speed mechanical systems with friction.
To seek and describe the influence of bubble size on geometric and motion characteristics of the bubble, six nozzles with different outlet diameters were selected to inject air into water and to produce different bubble sizes. High-speed photography in conjunction with an in-house bubble image processing code was used. During the evolution of the bubble, bubble shape, traveling trajectory and the variation of bubble velocity were obtained. Bubble sizes acquired varied from 0.25 to 8.69 mm. The results show that after the bubble is separated from the nozzle, bubble shape sequentially experiences ellipsoidal shape, hat shape, mushroom shape and eventually the stable ellipsoidal shape. As the bubble size increases, the oscillation of the bubble surface is intensified. At the stabilization stage of bubble motion, bubble trajectories conform approximately to the sinusoidal function. Meanwhile, with the increase in bubble size, the bubble trajectory tends to be straightened and the influence of the horizontal bubble velocity component on the bubble trajectory attenuates. The present results explain the phenomena related to relatively large bubble size, which extends the existing relationship between the bubble terminal velocity and the equivalent bubble diameter.
An innovative multi-robot simultaneous localization and mapping (SLAM) is proposed based on a mobile Ad hoc local wireless sensor network (Ad-WSN). Multiple followed-robots equipped with the wireless link RS232/485 module act as mobile nodes, with various on-board sensors, Tp-link wireless local area network cards, and Tp-link wireless routers. The master robot with embedded industrial PC and a complete robot control system autonomously performs the SLAM task by exchanging information with multiple followed-robots by using this self-organizing mobile wireless network. The PC on the remote console can monitor multi-robot SLAM on-site and provide direct motion control of the robots. This mobile Ad-WSN complements an environment devoid of usual GPS signals for the robots performing SLAM task in search and rescue environments. In post-disaster areas, the network is usually absent or variable and the site scene is cluttered with obstacles. To adapt to such harsh situations, the proposed self-organizing mobile Ad-WSN enables robots to complete the SLAM process while improving the performances of object of interest identification and exploration area coverage. The information of localization and mapping can communicate freely among multiple robots and remote PC control center via this mobile Ad-WSN. Therefore, the autonomous master robot runs SLAM algorithms while exchanging information with multiple followed-robots and with the remote PC control center via this local WSN environment. Simulations and experiments validate the improved performances of the exploration area coverage, object marked, and loop closure, which are adapted to search and rescue post-disaster cluttered environments.
This study presents a comprehensive comparison of the electro-osmosis treatments of heavy metal contaminated soil using electrokinetic geosynthetics (EKG) and iron electrodes in terms of both theoretical analysis and experimental research. The variation in the electrical parameters was analyzed, and the results show linear relationships between temperature and conductivity and between the soil and pore water conductivities. The average cathode contact resistance of iron is 60% smaller than that of EKG, whereas the average anode contact resistance of EKG is 56% smaller than that of iron. The values of the power consumption per unit mass of contaminants for EKG and iron are 1.895 and 1.989 kJ/g, respectively. After electro-osmosis, the number of soil pores increased, but the average area decreased, with an average area of 0.9100–1.0504 μm2. Based on microstructure analysis, we obtained higher electroosmotic efficiency and realized the effective analysis and utilization between macroscopic and microscopic parameters.
Excessive vibration and noise radiation of the track structure can be caused by the operation of high speed trains. Though the track structure is characterized by obvious periodic properties and band gaps, the bandwidth is narrow and the elastic wave attenuation capability within the band gap is weak. In order to effectively control the vibration and noise of track structure, the local resonance mechanism is introduced to broaden the band gap and realize wave propagation control. The locally resonant units are attached periodically on the rail, forming a new locally resonant phononic crystal structure. Then the tuning of the elastic wave band gaps of track structure is discussed, and the formation mechanism of the band gap is explicated. The research results show that a new wide and adjustable locally resonant band gap is formed after the resonant units are introduced. The phenomenon of coupling and transition can be observed between the new locally resonant band gap and the original band gap of the periodic track structure with the band gap width reaching the maximum at the coupling position. The broader band gap can be applied for vibration and noise reduction in high speed railway track structure.
The microstructure and mechanical properties of dissimilar pinless friction stir spot welded joint of 2A12 aluminum alloy and TC4 titanium alloy were evaluated. The results show that the joint of Al/Ti dissimilar alloys can be successfully attained through pinless friction stir spot welding (FSSW). The joint can be divided into three zones (SZ, TMAZ and HAZ). The microstructure of joint in Al alloy side changes significantly but it basically has no change in Ti alloy side. At the same rotation speed, the maximum load of welded joints gradually rises with the increase in dwell time. At the same dwell time, the maximum load of the welded joint increases with the increase of the rotational speed. In addition, optimal parameters were obtained in this work, and they are rotation speed of 1500 r/min, plunge speed of 30 mm/min, plunge depth of 0.3 mm and dwell time of 15 s. The fracture mode of welded joints is interfacial shear fracture. The microhardness of the joint on the Al side distributes in a typical “W” type and is symmetry along the weld center, but the distribution of the microhardness on the Ti side has no obvious change.
The waste dump of open-pit coal mine is remade of soil-rock mixture under the action of gravity, dynamic load of transportation equipment and earthquake, etc. By using artificial synthetic transparent soil, the developing process and migration law for soil-rock mixture are observed in the remade process. The mixture of fused quartz sand, liquid paraffin and n-tridecane is chosen as the material for synthetic transparent soil which is mixed with liquid paraffin and n-tridecane at a mass ratio of 4.4 at room temperature of 17℃. Physical and mechanical properties of transparent soil are determined by physical test and compared with those in natural sandy soil. The results show that transparent soil and sandy soil have high similarity, in other words, transparent soil can be used for similar simulation experiments of soil-rock mixture.
This paper investigates the effect of microwave irradiation on the β to α phase transformation of the β-nucleated isotactic polypropylene (iPP). Ten microwave irradiation cycles was applied to the iPP and iPP modified with 0.3 wt% and 0.5 wt% β-NA, and the data at 2nd, 4th, 6th, 8th and 10th irradiation were reported. As expected, the sample temperature was found to increase with the irradiation time, by more than 130 °C, due to high frequency of microwave processing. This was the major factor that induced the β-phase transformation and structural change. Both the differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results indicated that β-phase was mainly transformed to α-phase and partially converted to the amorphous section. It was reflected as 1) the reduction of the enthalpy of β-crystal melting (ΔHmβ), 2) the increased enthalpy of α-crystal melting (ΔHmα), 3) the decreased β-crystalline phase fraction (Kβ) and 4) the decrease of the overall degree of crystallinity (Xall). Under impact force, neat iPP showed a slight increase in the impact strength with the irradiation time, due to the increase of amorphous region. For the β-iPP, it decreased due to the reduction of the β-phase content.