Showing papers in "Journal of Central South University of Technology in 2005"
TL;DR: The issue of reducing energy consumption for the job-shop scheduling problem in machining systems is addressed and a heuristic algorithm is developed to locate the optimal or near optimal solutions of the model based on the Tabu search mechanism.
Abstract: The issue of reducing energy consumption for the job-shop scheduling problem in machining systems is addressed, whose dual objectives are to minimize both the energy consumption and the makespan. First, the biobjective model for the job-shop scheduling problem is proposed. The objective function value of the model represents synthesized optimization of energy consumption and makespan. Then, a heuristic algorithm is developed to locate the optimal or near optimal solutions of the model based on the Tabu search mechanism. Finally, the experimental case is presented to demonstrate the effectiveness of the proposed model and the algorithm.
47 citations
TL;DR: In this article, the magnetic signals of low carbon steel plate specimens were carried out on hydraulic servo testing machine of MTS810 type and magnetic signals were measured during the processes by the type of EMS-2003 instrument.
Abstract: In order to investigate the physical mechanism of metal magnetic memory testing, both the influences of earth magnetic field and applied stress on magnetic domain structure were discussed. Static tension and fatigue tests for low carbon steel plate specimens were carried out on hydraulic servo testing machine of MTS810 type and magnetic signals were measured during the processes by the type of EMS-2003 instrument. The results indicate that the initial magnetic signals of specimens are different before loading. The magnetic signals curves are transformed from initial random to regular pattern due to the effect of two types of loads. However, the shape and distribution of magnetic signal curves in the elastic region are different from that of plastic region in tension test. While in fatigue test those magnetic signals curves corresponding to different cycles are similar. The Hp(y) value of magnetic signals on the fracture zone increases dramatically at the breaking transient time and positive-negative magnetic poles occur on the two parts of fracture zone.
37 citations
TL;DR: In this paper, the solvent extraction of copper and zinc from the bio-leaching solutions of low-grade sulfide ores with LIX984 and D2EHPA was investigated.
Abstract: The solvent extraction of copper and zinc from the bioleaching solutions of low-grade sulfide ores with LIX984 and D2EHPA was investigated. The influences of extractant content, aqueous pH value, phase ratio and equilibration time on metals extraction were studied. The results show that LIX984 has a higher selectivity for copper than for iron, zinc and other metals, and has the copper extraction rate above 97%, while the zinc and iron extraction rate is less than 1.6% respectively. Zinc extraction is carried out following the copper extraction from the raffinate. The zinc extraction with di(2-ethylhexyl) phosphoric acid (D2EHPA) is low due to its poor cation exchange. A sodium salt of D2EHPA is used and the zinc extraction rate is enhanced to above 98%. Though iron (III) is strongly extracted before the extraction of zinc by D2EHPA, it is difficult to strip iron from the organic phase by sulfuric acid. The zinc stripping rate is above 99% with 100 g/L sulfuric acid, while that of iron is 0.16%. Hence, the separation of zinc from iron can be achieved by the selective stripping.
32 citations
TL;DR: In this article, the damage and failure rule of rock under different uniaxial compressive loads and dynamic loads was analyzed, and according to the equivalent strain hypothesis, a new constitutive model of elastic-plastic damage was established, and then the calculated results with the established model were compared with test results to show a good agreement.
Abstract: For understanding the damage and failure rule of rock under different uniaxial compressive loads and dynamic loads, tests on red sandstone were carried out on Instron 1342 electro-servo controlled testing system with different uniaxial compressive loads of 0, 2, 4 and 6 MPa. It is found that peak stress, peak strain, elastic modulus and total strain energy decrease with the increase of static compressive stress. Based on the test results, the mechanism on damage and failure of rock was analyzed, and according to the equivalent strain hypothesis, a new constitutive model of elastic-plastic damage was established, and then the calculated results with the established model were compared with test results to show a good agreement. Furthermore the rule of releasing ratio of damage strain energy was discussed.
29 citations
TL;DR: In this article, the performance of printed circuit board (PCB) was studied on several crushers, and the results showed that PCB is a material which is difficult to crush.
Abstract: The crushing performance of printed circuit board (PCB) was studied on several crushers. The results show that PCB is a material which is difficult to crush. The crushing performance of PCB with disk crusher, especially vibration grinding, which has cut or impact action, excels that of jaw crusher or roller crusher. The PCB scrap is worthwhile to recycle using variety of modern characterization methods. When compared with natural resources, this material stream remains a rich precious metal and nonferrous metals. In PCB scrap, metals account for 47% of the total material composition, in which there exists 19.66% copper, 11.47% iron, 3.93% lead, 300 g/t gold and 5–10 kg/t silver, etc. In addition, the PCB scrap contains 27% of plastics and 26% of refractory oxides.
26 citations
TL;DR: In the course of creating immense wealth, manufacturing industry has excessively consumed the resources and energy in the earth, and seriously polluted the environment as discussed by the authors, and the remanufacturing engineering is the industrialization of high-tech maintenance of the waste and worn productions, and is one of the most active factors in 4R.
Abstract: In the course of creating immense wealth, manufacturing industry has excessively consumed the resources and energy in the earth, and seriously polluted the environment. To take progress as the sustainable development way, save resource and improve environment, our nation has been advocating to construct the cycle economy and saving-oriented society. Taking the remanufacturing engineering as the representative, the “4R” rule (Reduce, Reuse, Recycle and Remanufacture) is the important measure to get the goal. Remanufacturing engineering is the industrialization of high-tech maintenance of the waste and worn productions, and is one of the most active factors in “4R”. The development of high and new technology takes the important effect to promote the remanufacturing engineering.
24 citations
TL;DR: In this article, high purity active γ-Al2O3 nanoparticles were synthesized from aluminum nitrate and ammonium carbonate with a little surfactant by chemical precipitation method.
Abstract: Highly pure active γ-Al2O3 nanoparticles were synthesized from aluminum nitrate and ammonium carbonate with a little surfactant by chemical precipitation method. The factors affecting the synthesis process were studied. The properties of γ-Al2O3 nanoparticles were characterized by DTA, XRD, BET, TEM, laser granularity analysis and impurity content analysis. The results show that the amorphous precursor Al(OH)3 sols are produced by using 0.1 mol/L Al(NO3)3 · 9H2O and 0.16 mol/L (NH4)2CO3 · H2O reaction solutions, according to the volume ratio 1.33, adding 0.024% (volume fraction) surfactant PEG600, and reacting at 40 °C, 1 000 r/min stirring rate for 15 min. Then, after stabilizing for 24 h, the precursors were extracted and filtrated by vacuum, washed thoroughly with deionized water and dehydrated ethanol, dried in vacuum at 80°C for 8 h, final calcined at 800 °C for 1 h in the air, and high purity active γ-Al2O3 nanoparticles can be prepared with cubic in crystal system, OH7-FD3M in space group, about 9 nm in crystal grain size, about 20 nm in particle size and uniform size distribution, 131. 35 m2/g in BET specific surface area, 7 – 11 nm in pore diameter, and not lower than 99.93% in purity.
24 citations
TL;DR: A mobile robot developed by Wuhan University for full-path inspection on 220 kV transmission lines was presented in this article, where Lagrange equations were utilized to derive dynamic equations of all the links, including items of inertia, coupling inertia, Coriolis acceleration, centripetal acceleration and gravity.
Abstract: A mobile robot developed by Wuhan University for full-path hotline inspection on 220 kV transmission lines was presented. With 4 rotating joints and 2 translational ones, such robot is capable of traveling along non-obstacle straight-line segment and surmounting straight-line segment obstacles as well as transferring between two spans automatically. Lagrange’s equations were utilized to derive dynamic equations of all the links, including items of inertia, coupling inertia, Coriolis acceleration, centripetal acceleration and gravity. And a dynamic response experiment on elemental motions of robot prototype’s travelling along non-obstacle straight-line segment and surmounting obstacles was performed on 220 kV 1:1 simulative overhanging transmission-line in laboratory. In addition, dynamic numerical simulation was conducted in the corresponding condition. Comparison and analysis on results of experiment and numerical simulation have validated theoretical model and simulation resolution. Therefore, the dynamic model formed hereunder can be used for the study of robot control.
23 citations
TL;DR: In this paper, the dispersion problem of nano-copper was investigated by surface treatment and high dispersion, and the results indicated that the methods of the preparation and dispersion can obtain 20 nm copper additive with good dispersion property in lubrication oil.
Abstract: Nano-copper used as lubrication oil additive has good tribological property and active self-repairing effect for friction pairs. The reduction in liquid phase for preparing nano-additive is one of the most common method. Nano-copper was prepared by reduction in liquid phase. The different project and routine practice for preparing nano-copper were researched. The dispersion problem of nano-copper was investigated by surface treatment and high dispersion. The particles dimension, the dispersion stability and the purity of nano-copper were characterized by TEM and XRD. The conclusion indicates that the methods of the preparation and dispersion can obtain 20 nm copper additive with good dispersion property in lubrication oil.
22 citations
TL;DR: In this article, the wavelet transform and wavelet packet analysis were used to study the energy distribution of short-time non-stationary random signals in different blasting conditions by means of MATLAB; energy distribution for different frequency bands is obtained.
Abstract: Blast vibration analysis constitutes the foundation for studying the control of blasting vibration damage and provides the precondition of controlling blasting vibration. Based on the characteristics of short-time non-stationary random signal, the laws of energy distribution are investigated for blasting vibration signals in different blasting conditions by means of the wavelet packet analysis technique. The characteristics of wavelet transform and wavelet packet analysis are introduced. Then, blasting vibration signals of different blasting conditions are analysed by the wavelet packet analysis technique using MATLAB; energy distribution for different frequency bands is obtained. It is concluded that the energy distribution of blasting vibration signals varies with maximum decking charge, millisecond delay time and distances between explosion and the measuring point. The results show that the wavelet packet analysis method is an effective means for studying blasting seismic effect in its entirety, especially for constituting velocity-frequency criteria.
22 citations
TL;DR: In this article, the life cycle index of remanufactured engines was assessed by using the method of life cycle assessment (LCA) and the results indicated that remanufacturing an engine can save 55 kg steels, 8.3 kg aluminum and 113 kW · h electric powers and reduce emissions of 565 kg CO2, 6.09 kg CO, 1.01 kg NOx, 3.985 kg SOx and 288.725 kg solid waste.
Abstract: The life cycle index of remanufactured engines was assessed by using the method of life cycle assessment (LCA). A remanufactured engine of a certain domestic brand was taken as researching object. Engine reproducing engineering was investigated from three aspects which were energy, material and environment. The application of LCA on remanufacturing engines was discussed in detail with a practical case. The results indicate that remanufacturing an engine can save 55 kg steels, 8.3 kg aluminum and 113 kW · h electric powers and reduce emissions of 565 kg CO2, 6.09 kg CO, 1.01 kg NOx, 3.985 kg SOx and 288.725 kg solid waste. The remanufacturing of engines possesses great economic value and practicability.
TL;DR: In this paper, a microwave-assisted method was used to extract polysaccharides from solanum nigrum, and the results showed that compared with the conventional reflux extraction, the microwave assisted extraction has a higher yield in shorter time, with no effect on the finally obtained polyscharides as seen from the FT-IR spectra.
Abstract: The microwave-assisted method was used to extract polysaccharides from solanum nigrum. The optimum experimental parameters, mechanism of the extraction and the effect of microwave-assisted extraction process on the structures of polysaccharides were investigated. The extract was analyzed by the modified phenol-sulfuric acid method at 490 nm. The optimum experimental parameters were obtained by orthogonal experiments as follows: extraction time 15 min, microwave radiation power 455 W and the process ratio of materials mass to solvent volume 1:20. The results show that compared with the conventional reflux extraction, the microwave-assisted extraction has a higher yield in shorter time, with no effect on the finally obtained polysaccharides as seen from the FT-IR spectra. The scanning electron microscopy images reveal that the mechanism of the extraction is related to the structural changes of the plant cells in different extracting conditions.
TL;DR: In this article, the performance of the nano-diamond particles was analyzed by means of X-ray photoelectron spectroscopy (XPS) and the results showed that the nanodiamond particles can improve the antiwear and friction reducing properties of the base oil at high temperature and high load.
Abstract: The tribological behaviors of the nano-diamond particles including the nano-diamond and the nano-diamond modified were studied at high temperature using SRV multifunctional test system. The worn steel surfaces were analyzed by means of X-ray photoelectron spectroscopy (XPS). The results show that nano-diamond particles can obviously improve the antiwear and friction reducing properties of the base oil at high temperature and the high load. The friction coefficient of the nano-diamond is very low at 200 °C when the test load is not more than 20 N. This tribological behaviors should attributed to the similarly to “ball bearing” lubrication action of the nano-diamond particles, so the movement between tribological pairs become sliding/rolling. The nano-diamond modified by dimer ester possesses excellent antiwear and friction reducing performance at 500 °C and load 500 N. The tribochemical reaction film between the nano-diamond particles and the renascent wear surface plays dominating lubrication role and the presence of the dimer ester on the rubbing surface can be propitious to form lubrication film containing nano-diamond on the worn surface at high temperature and high load.
TL;DR: With the security problem of image information as the background, some more properties of the period of Arnold transformation of two-dimension were studied by means of introducing a integer sequence and two interesting conjectures are given.
Abstract: With the security problem of image information as the background, some more properties of the period of Arnold transformation of two-dimension were studied by means of introducing a integer sequence. Some new results are obtained. Two interesting conjectures on the period of Arnold transformation are given. When making digital images scrambling by Arnold transformation, it is important to know the period of the transformation for the image. As the application of the theory, a new method for computing the periods at last are proposed.
TL;DR: In this paper, the effects of reaction temperature and pressure on the ingredient of crude lactide were investigated, and the results showed that the mass fraction of meso-lactide increases with the increasing reaction temperature.
Abstract: L-lactide was prepared from L-lactic acid with stannous octoate as the catalyst. The effects of reaction temperature and pressure on the ingredient of crude lactide were investigated. The results show that the mass fraction of meso-lactide increases with the increasing reaction temperature. Crude lactide containing 85.4% L-lactide is obtained when the reaction temperature is 200 °C. High purity of L-lactide with a yield of 40.6% is obtained by synthetic purifying method. The properties of L-lactide are characterized by optical purity, infrared spectrum and gas chromatogram/mass spectrum. The L-lactide samples purified by recrystallization and synthetic purifying methods are polymerized with the catalyst of stannous octoate, and the corresponding viscosity average relative molecular masses of poly(L-lactide) are 2.85×105 and 5.05×105, respectively. This indicates that the optical purity of L-lactide has great influence on the relative molecular mass of poly(L-lactide).
TL;DR: In this paper, the first automobile engine remanufacture company in China, Jinan Fuqiang Power Co, Ltd, was introduced, and the benefit statistic of remanufacturing 10, 000 Styer engines were analyzed.
Abstract: The first automobile engine remanufacture company in China, Jinan Fuqiang Power Co, Ltd, was introduced. The engine remanufacturing technological process of this company was described. The benefit statistic of remanufacturing 10 000 Styer engines were analyzed, and the contribution of engine remanufacturing to cycle economy was predicted. The results show that remanufacturing engineering could use the maximal additional values of obsolete engines, and make contributions to materials conservation, capital saving, energy conservation and environment protection. 10 000 engines are supposed to be remanufactured per year, the following benefits would be obtained: reclaiming additional values of RMB3.23 hundred million, saving metallic materials about 7.65 thousand tons, saving energy of 16 million kilowatt-hours, reducing emission of CO2 about 11.3–15.3 thousand tons, and providing employment for 500 persons. According to the survey and analysis, tremendous benefits will be gained by the year of 2020. For example, reclaiming additional values per year of 1424–2236 hundred million RMB, saving energy per year of 60–90 hundred million kilowatt-hours, reducing emission of CO2 about 6.67–9.69 million tons. It can be deduced that developing remanufacturing will play an important role in enriching the cycle economy and accelerating the development of national economy.
TL;DR: In this article, the influence of ultra-fine fly ash on the hydration shrinkage of composite cementitious materials was investigated, and the results showed that the ultra fine fly ash can restrain the fluid shrinkage to a certain degree.
Abstract: Hydration shrinkage generated by cement hydration is the cause of autogenous shrinkage of high strength concrete. It may result in the volume change and even cracking of mortar and concrete. According to the data analysis in a series of experimental studies, the influence of ultra-fine fly ash on the hydration shrinkage of composite cementitious materials was investigated. It is found that ultra-fine fly ash can reduce the hydration shrinkage of cement paste effectively, and the more the ultra-fine fly ash, the less the hydration shrinkage. Compared with cement paste without the ultra-fine fly ash, the shrinkage ratio of cement paste reduces from 23.4% to 39.7% when the ultra-fine fly ash replaces cement from 20% to 50%. Moreover, the microscopic mechanism of the ultra-fine fly ash restraining the hydration shrinkage was also studied by scanning electron microscopy, X-ray diffraction and hydrated equations. The results show that the hydration shrinkage can be restrained to a certain degree because the ultra-fine fly ash does not participate in the hydration at the early stage and the secondary hydration products are different at the later stage.
TL;DR: In this article, a green manufacturing problem framework of machining systems is presented to describe the traits of input, output and control elements in the machining system, and a series of investigations and practices on green manufacturing in machining process are described.
Abstract: A machining system is a typical manufacturing system. A green manufacturing function framework of machining systems is structured to describe the traits of input, output and control elements in the system. Based on the function framework, the green manufacturing problem framework of machining systems is presented. The green manufacturing problems in machining systems are classified into three classes and related series of subclass problems. The three classes of problems in the green manufacturing problem framework are the problems of the minimization of resource consumption, the minimization of environmental discharge, and the synthesized minimization of both of them. A series of investigations and practices on green manufacturing in machining system, performed by the authors for quite a long period, are introduced in brief, such as the optimizing system for raw material cutting, the matching system for energy-saving in machining, the design of highly efficient dry hobbing machine tools, the multi-objective decision-making model for green manufacturing in machining systems, and the decision-making supporting system for green manufacturing in machining processes.
TL;DR: In this article, the reverse-flotation technology of bauxite was investigated, and the results showed that sodium hexmetaphosphate has different depression on the flotation of diaspore and kaolinite.
Abstract: In order to offer high grade concentrate to produce alumina by Bayer, the reverse-flotation technology of bauxite was investigated. The results show that sodium hexmetaphosphate has different depression on the flotation of diaspore and kaolinite. The recoveries of diaspore decrease markedly with the increase of the concentration of sodium hexmetaphosphate with dodecyl-amine as collector. Fourier transform infrared spectra indicate that the absorbance band 875 cm−1 of the asymmetric stretching vibration of bridge oxygen P-O-P shifts to 880 cm−1, and the 1 264 cm−1 of the asymmetric stretching vibration of the bridge PO2 shifts to 1 267 cm−1 in the diaspore’s spectra. This demonstrates that sodium hexmetaphosphate interacts through bridging PO2 groups with the Al atoms exposed on the diaspore and kaolinite surfaces to form P-O-Al bond. Adsorption measurements also testify that sodium hexmetaphosphate adsorbs easily on the surface of diaspore. The adsorption density of PO3− on the surface of diaspore is about 4.7 × 10−6 mol/m2, while that on the kaolinite is only about 3.5 × 10−7 mol/m2 when pH value is 6.
TL;DR: In this article, the main constituents of essential oils of Angelica sinensis root were identified by GC-MS with the help of subwindow factor analysis (SFA) method resolving two-dimensional original data into mass spectra and chromatograms.
Abstract: Gas chromatography — mass spectrometry (GC-MS) coupled with chemometric resolution upon two-dimensional data was employed to analyze the constituents of essential oils of essential oils of Angelica sinensis. Constituents in essential oils of Angelica sinensis root were identified by GC-MS with the help of subwindow factor analysis (SFA) method resolving two-dimensional original data into mass spectra and chromatograms. 76 of 97 separated constituents in essential oil of Angelica sinensis root were identified and quantified, and they account for about 91. 36% of the total content. The results show that ligustilide, butylene phthalide, 2-methoxy-4-vinylphenol, carvacrol, alloocimene,2,6,6-trimethylbicyclo-[3,1,1]hept-2-ene are the main constituents in essential oil of Angelica sinensis root.
TL;DR: In this paper, the consumption of sodium sulfide and the concentration of antimony in the leaching solution of two-stage leaching of jamesonite concentrate and combination leach of high-grade stibnite concentrate and jamesite concentrate were investigated.
Abstract: Sodium sulfide leaching of a low-grade jamesonite concentrate in the production of sodium pyroantimoniate through the air oxidation process and the influencing factors on the leaching rate of antimony were investigated In order to decrease the consumption of sodium sulfide and increase the concentration of antimony in the leaching solution, two-stage leaching of jamesonite concentrate and combination leaching of high-grade stibnite concentrate and jamesonite concentrate were used The experimental results show that the consumptions of sodium sulfide for the two-stage leaching process and the combination leaching process are decreased by 20% and 60% compared to those of one-stage leaching process respectively The final concentrations of antimony in the leaching solutions of both processes are above 100 g/L
TL;DR: In this article, a new method was proposed to cope with the earth slope reliability problem under seismic loadings, which integrates the concepts of artificial neural network, the first order second moment reliability method and the deterministic stability analysis method of earth slope.
Abstract: A new method was proposed to cope with the earth slope reliability problem under seismic loadings. The algorithm integrates the concepts of artificial neural network, the first order second moment reliability method and the deterministic stability analysis method of earth slope. The performance function and its derivatives in slope stability analysis under seismic loadings were approximated by a trained multi-layer feed-forward neural network with differentiable transfer functions. The statistical moments calculated from the performance function values and the corresponding gradients using neural network were then used in the first order second moment method for the calculation of the reliability index in slope safety analysis. Two earth slope examples were presented for illustrating the applicability of the proposed approach. The new method is effective in slope reliability analysis. And it has potential application to other reliability problems of complicated engineering structure with a considerably large number of random variables.
TL;DR: In this article, the mechanical properties and microstructures of as-cast and extruded Mg-Ce-Zn-Zr alloys have been made before and after heat treatment.
Abstract: Studies on the mechanical properties and microstructures of as-cast and extruded Mg-Ce-Zn-Zr and Mg-Nd-Zn-Zr alloys have been made before and after heat treatment. The results show that the mechanical properties of as-cast Mg-Ce and Mg-Nd alloys are as good as those of typical die cast AZ91 alloy and the heat resistant WE43 alloy. In Nd-containing alloys, the precipitated phase Mg12 Nd contributes significantly to age hardening. The mechanical properties of extruded alloys are improved obviously compared with those of as-cast alloys. The ultimate strength is 257.8 MPa for extruded Mg-Ce alloy and 265.6 MPa for extruded Mg-Nd alloy. Extrusion is a useful method to improve both the strengths and elongations of the two experimental alloys at both ambient and elevated temperatures. The grain refinement and precipitation strengthening are the main strengthening mechanisms in the alloys. Tensile fracture surfaces show a dimple pattern after extruding and therefore reflect an improved elongation.
TL;DR: In this paper, a load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in order to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip.
Abstract: The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-softening, ideal elasto-plastic and work-hardening, a universal tri-linear load transfer model is suggested for the development of side and tip resistance by various types of soil (rock) with the consideration of sediment at the bottom of the pile. Based on the model, a formula is derived for the relationship between the settlement and load on the pile top to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip. A close agreement of the calculated results with the measured data from a field test pile lends confidence to the future application of the present approach in engineering practice.
TL;DR: In this article, the surface modified nanocopper particles were prepared with chemical reduction method, and the wear test was carried out on a T-11 ball-on-plate friction and wear tester made in Poland.
Abstract: The surface modified nanocopper particles were prepared with chemical reduction method. The wear test was carried out on a T-11 ball-on-plate friction and wear tester made in Poland. The material of the upper sample was GCr15 and the counterpart was AISI-1045 steel. The morphologies of the worn surfaces of the samples were observed by optical microscope and scanning electron microscope, while the element distributions on the worn surfaces were determined by means of electron microprobe analysis. As the results, a film mainly made of Cu is formed on the worn surface. The film on the surface of the still upper sample is thicker than that formed on the revolving counterpart. At the edge of the groove of the worn surface made by the milling before test there is Cu element observed obviously, but there is not any Cu element in the bottom of the groove. A possible action mechanism of the film is suggested. The friction movement can induce reactivity of the metal and continuously produce activation surface. It benefits the film formed by nano-Cu in lubricant on the worn surface. Hardness and modulus of nano-Cu films were successfully measured and analyzed by the nanoindentation instrument. The results show that the hardness and modulus of the films are lower than those of the initial surface.
TL;DR: In this paper, the authors used flocculation-high intensity magnetic separation (FIMS) and adding hydrolyzed and causticized flocculants according to the characteristic of iron fine.
Abstract: Successful recovery of limonite from iron fines was achieved by using flocculation-high intensity magnetic separation (FIMS) and adding hydrolyzed and causticized flocculants according to the characteristic of iron fines. The separation results of the three iron samples are as follows: iron grade 66.77%–67.98% and the recovery of iron 69.26%–70.70% by the FIMS process with flocculants. The comparative results show that under the same separation conditions the FIMS process can effectively increase the recovery of iron by 10.97%–15.73%. The flowsheet results confirm the reliability of the process in a SHP high intensity magnetic separator. The concentrate product can be used as raw materials for direct reduction iron-smelting. The hydrolyzed and causticized flocculants can selectively flocculate fine feebly-magnetic iron mineral particles to increase their apparent separation sizes. The larger the separation size, the stronger the magnetic force. By comparing the separation results of the three samples it is found that among the three samples the higher the limonite content, the better the separation result. This means that the separation result relates closely to the flocculation process and the adding pattern of the flocculant.
TL;DR: In this article, ground penetrating radar (GPR) was used to detect cracks in tunnel linings, and the results showed that GPR is accurate and efficient to detect tunnel cracks.
Abstract: Lining craze, as a common engineering damage, affects the bearing capacity and the safety of tunnels. To improve the capabilities of the surface crack detection in the tunnel lining, ground penetrating radar (GPR) was employed. The principle and method of GPR for cracks investigation of tunnel lining were expounded. As an application example, some field measurements in order to detect the depth of cracks for the tunnel lining were achieved in a new tunnel. All GPR investigations were made with the antennae of 1 GHz. The cracks of concrete structure were located, and the distributing and depth of cracks are inspected and estimated by GPR. The results of investigation show GPR is accurate and efficient to detect cracks of tunnel lining.
TL;DR: In this article, the authors evaluated the influence of the added external circulation on the development of granular sludge taken from the two tested laboratory-scale reactors during start-up.
Abstract: The start-up of external circulation — added internal circulation (IC) reactor was finished in 26 d, 32 d fewer than that of IC reactor. To evaluate the influence of the added external circulation on the development of granular sludge, the characteristics of the granular sludge taken from the two tested laboratory-scale reactors during start-up were studied. The results show that the added external circulation can enhance biomass granulation, accelerate granule development and improve sludge characteristics. At the end of start-up, the granular size of sludge in external circulation-added IC reactor greatly increases with a size distribution much better than that of sludge in IC reactor. The granular sludge originated from external circulation — added IC reactor contains more extracellular polymers and has a greater settling velocity than that from IC reactor. Methanogenic activity of the granular sludge from the external circulation — added IC reactor started 26 d ago reaches 358.23 mL · g−1 · d−1, 1.66 and 1.20 times as great as that of the sludge from the IC reactor started 26 d and 58 d ago respectively.
TL;DR: Based on the slice method of the non-circular slip surface for the calculation of integral stability of slope, an improved genetic algorithm was proposed, which can freely search for the most dangerous slip surface of slope and the corresponding minimum safety factor without supposing the geometric shape of the most Dangerous slip surface as discussed by the authors.
Abstract: Based on the slice method of the non-circular slip surface for the calculation of integral stability of slope, an improved genetic algorithm was proposed, which can freely search for the most dangerous slip surface of slope and the corresponding minimum safety factor without supposing the geometric shape of the most dangerous slip surface. This improved genetic algorithm can simulate the genetic evolution process of organisms and avoid the local minimum value compared with the classical methods. The results of engineering cases show that it is a global optimal algorithm and has many advantages, such as higher efficiency and shorter time than the simple genetic algorithm.
TL;DR: In this paper, a support vector machine with guadratic polynomial kernel function based nonlinear model multi-step-a-head optimizing predictive controller was presented, and a quadratic objective function with receding horizon was selected to obtain the controller output.
Abstract: A support vector machine with guadratic polynomial kernel function based nonlinear model multi-step-a-head optimizing predictive controller was presented. A support vector machine based predictive model was established by black-box identification. And a quadratic objective function with receding horizon was selected to obtain the controller output. By solving a nonlinear optimization problem with equality constraint of model output and boundary constraint of controller output using Nelder-Mead simplex direct search method, a sub-optimal control law was achieved in feature space. The effect of the controller was demonstrated on a recognized benchmark problem and a continuous-stirred tank reactor. The simulation results show that the multi-step-ahead predictive controller can be well applied to nonlinear system, with better performance in following reference trajectory and disturbance-rejection.