Abstract: In order to acknowledge the adsorption property of Tianjin shallow porous aquifer medium to Fe and the transportation law of Fe in salt and fresh water aquifer, seven soil samples were made using 2 bores' core in Baodi county and Dagang district. Static adsorption experiments and dynamic filtering pole experiments were conducted with FeSO4 liquor simulating contamination. The results showed that the adsorption mode of soil samples to Fe was the Langmuir isothermal adsorption equation, and it was taken 3 500 days to transport 4 m for Fe in fresh aquifer then 4 400 days in salt aquifer. Therefore, the extra heavy concentration of Fe at individual sites would not induce large area of groundwater pollution.
Abstract: This paper investigated the comprehensive in-situ engineering and environmental characteristics of No. 38 excavation disturbed zone (EDZ) at the depth of 600 m in Shizuishan Mine in western China. The mineral composition, physical characteristics and mechanical properties in nature and saturation conditions of sandstone and mud-stone were analyzed by microscope and material testing machine. The collapsing regularity and stress characteristics of soft rock in the complex stress environment of deep mining were quantificationally gained based on deformation and stress monitoring and tectonic detecting.
Abstract: The stress distribution and its evolution modes in surrounding rocks of a roadway were comprehensively studied with respect to different pillar widths, where the roadway had been protected by an irregular pillar remained along the goaf in mechanized top-coal caving mining and supported by bolt-mesh technique. The study manifested the uncoupled pattern of the peak stresses in vertical and horizontal directions, as well as the stress evolution trace varying with pillar width. The control variable was pointed out for the mechanical system, and the different stability areas were distinguished correspondent to its value. Through the general analysis and assessment on stability of the roadway system protected by the pillar with different widths, the reasonable pillar width was promoted for effective protection of the roadway in mechanized top-coal caving mining panel. A comprehensive control technique was proposed and employed in practice through reinforcing the irregular pillar as a main way and hanging the mesh and bolt rock mass as a auxiliary means to support the gateway remained along the goal.
Abstract: Based upon comprehensive analyses of the rock property parameters that may affect blastability, linear correlation analysis was made on the data obtained from the tests of static and dynamic properties, specific gravity and integrity coefficient of 14 types of rock. The result showed that the static tensile strength and specific gravity of rock, together with the integrity coefficient of rock-mass are lightly, or merely not, correlated. It was proposed that these three parameters, together with dynamic compressive strength, could be used to serve as the basic indexes for quantitative description of blastability of common rock-masses. Thereafter weighted clustering analysis was conducted and a new rock blastability classification method was established for an open pit mine of Ben-gang Mining Industry Company.
Abstract: This paper studied the situation of cultivating the biofilms with two different flow modes in an inner loop three-phase fluidized bed. The results showed that the diameter of the biofilm formed in a se quencing batch reactor (SBR) could increase to about 200~250μm, and that formed in a continuance reactor could arrive at 100μm. The former biofilm is smooth and compact, but the later has a higher activity. A lower initial loading rate makes for suspension membrane, and in the successive process, the loading rate can not be excessively low. Otherwise filamentous colonies expand because of the low loading rate. The biomass density of active sludge with SBR mode could increase to 9.65 g·L-1, 92.7 % of which is attachment biofilm, and the loading rate of COD with continuance mode could arrive at 11.45 kg·m-3·d-1.
Abstract: S2-, Fe2+ and bacteria in oilfield produced water could degrade polyacrylamide and decrease the polymer solution's viscosity seriously. An Mn Ce complex oxide catalyst was prepared by impregnation method to treat oilfield-produced water by multi-phase catalytic oxidation, The results showed that the catalyst was high effective and stable. The viscosity of the polymer solution made of simulated oilfield produced water processed by the oxidation was 5.48 times higher than that unprocessed.
Abstract: The large-scale commercial computational fluid dynamics software CFX4.3 was applied to numerically simulate the fume distribution in the top dome of a cowper internal combustion stove of blast furnace with a volume of 1 200 m3 in XinGang of China. The standard k-ε model and SIMPLE algorithm were used in this simulation. The results show that the hot gas distribution in a catenary dome is evener than that in a hemispheroid dome, and the distribution of hot gas is improved to some extent with the dome height increasing.
Abstract: The cluster-agglomeration pattern was simulated with DLA model in the fractal theory to study the agglomeration process of a great number of inclusion particles in molten steel. The results show that the shapes of agglomerates are alike to the cluster type inclusion particles in molten steel. By the rule in the fractal theory the agglomeration process can be considered as follows. Numerous inclusion particles aggregate to form smaller clusters firstly, and then they come together into large agglomerates. The agglomerating times of clusters equal in size are different, The shapes of clusters with the same initial condition of agglomeration are also different. The inclusion growth rate by agglomeration increases with increasing shift step length and concentration of particles. The average value of shift step length of particles is decided by the viscosity of molten steel and the size of particles with a great degree. The distribution of agglomerates and the size of clusters vary with the agglomerating time and the average shift step length of particles.
Abstract: The great engineering software ANSYS was used to simulate the induction heating process of a continuous casting square billet in multi-physical coupling field based on the electromagnetic induction and heat exchange theory. The analyzed results of temperature gradient and magnetic field distribution in the section of the casting billet after induction heating were consistent with the measured ones.
Abstract: An advanced description method of initial fatigue quality was proposed, in which neural network interpolation is employed instead of Lagrange interpolation to compute the values of the time to crack initiation (TTCI) and maximum likelihood estimation is used to estimate TTCI distribution parameters instead of mean rank estimation. Taking account into the randomicity encountered when only one group of TTCI values is used to estimate distribution parameters, several groups of TTCI distribution parameters were gained after maximum likelihood estimating for several groups of TTCI values corresponding to the given reference crack sizes. Then, equivalent initial flaw size distribution can be confirmed based on the relations of several groups of TTCI distribution parameters. The fatigue test of some component and its initial fatigue quality analysis show that the advanced method is feasible and reasonable.
Abstract: The intragranular nucleation phenomena of ferrite in low carbon steels with oxides of CaO and CeO2 were studied using a method of hot diffusion bonding. The experimental results showed that the fine intragranular acicular ferrite structure in low carbon steels with oxides of CaO and CeO2 was induced by heterogeneous nucleation of ferrite plates at fine dispersed CaO and CeO2 particles. There were large thermally induced strain regions in the neighbourhood of CaO and CeO2. The presence of these regions provided dominant driving force for the nucleation of acicular ferrite, which led to multiple nucleations on the inclusion. Meanwhile a large quantity of new austenite/ferrite high energy interfaces formed, which provided the surface effect of the sympathetical nucleation. The optimum size of oxides for adequate nucleation of acicular ferrite was 0.1 to 0.6μm.
Abstract: Gelcasting was applied to the preparation of high carbon steel products with 1% carbon in mass fraction. The iron-carbon suspension with 89 % solid loading was prepared in gelcasting and a lot of parts with complex shapes were produced with this suspension. The effect of sintering atmosphere on the carbon content of products was investigated. It is shown that sintering in vacuum can control the carbon content. The products with uniform structure,, a relative density of 91%, flexural strength of 400 MPa, and tensile strength of 410 MPa can be prepared after sintering at 1 200 ℃ under dissociated ammonia.
Abstract: ABSTRACT The effects of Zr and Nb dopants on the microstructure and magnetic properties of exchangecoupling nanocomposite Nd8.60Fe80.80Cu0.3Zr2-xNbxB8.30(x=0,1,2) ribbons were systematically studied. It is found that both Zr and Nb dopants can suppress the magnetic grain growth efficiently. The combination of Zr and B consumes partial B and induces to the reduction N2Fe14B phases. Comparing to the effect of Zr addition, Nb addition can improve the squareness of the hysteresis loop and suppress the magnetic grain growth more effectively. The optimum magnetic properties were found in the annealed Nd8.60Fe8 0.80Cu0.3Nb2B8.30 ribbons as the following: Br=0.89T,Hci=479.1kA·m-1,(BH)max=107.4kJ·m-3.
Abstract: The microstructure of an in-situ reactive spray formed TiCp/7075 (TiCp = 2.91% in volume fraction) Al alloy was observed using SEM. The grain sizes were measured by Image Tool software and a mean linear intercept method and compared with that of spray formed 7075 Al alloys. The result showed that the grain size of the former alloy was decreased 50 % compared to the later. It is indicated that in-situ TiC particles play a significant role on refining the microstructure of spray formed 7075 Al alloys. The refinement mechanism was interpreted from nucleation attribute, nucleation velocity and crystallographic analysis in nucleation process.
Abstract: This paper investigated the influencing factors on the leakage behavior of strontium titanate form SrTiO3a. The leaching rate was evaluated by the materials characterization center method. Experimental results showed that the leaching rate of SrTiO3a gradually decreased with time and was less than 0.1 g·m-2·d-1, twice orders less than that of glass solid. It was found that SrTiO3a had a steady chemical property and was a good form for high lever radioactive-wastes.
Abstract: The paper expatiated the structure and designed demand of the housing of a H1400 heavy cross wedge rolling mill developed by the authors. A coupling method of boundary element method and finite element method was adopted to numerically simulate the deformation of main parts during the process of cross wedge rolling and accurately calculate the strength and rigid of the mill. The results show that the designed structure of the housing of a H1400 heavy cross wedge rolling mill provides effective equipment for meeting the market demand and rolling large-sized shaft-parts.
Abstract: Particle wake has obviously effects on particle-particle interactions and two-phase flow characteristics in dense gas-particle two-phase flow. The large eddy simulation method was used to study the flow field across a ϕ100μm particle. The local streamline, velocity and pressure distribution at different Reynolds numbers Rep were calculated. The results reveal that at Rep = 100 the length of particle wake region is about 5 times the particle diameter and the corresponding maximum pressure difference is 373.48 Pa.
Abstract: Based on the definition of crushing ratio, the moisture loss and drying characteristic of crushed stems of the alfalfa at different crushing ratios and pressures were studied. The influence of leaf numbers attached on an alfalfa stem on the drying rate was analyzed and compared with that of a single leaf and a single stem. The shrinkages of stems and leaves before and after drying were comparatively investigated. The results show that drying temperature has significant influence on alfalfa stems with bigger diameters and less crushing ratios. At drying temperatures of 100℃ and 80 ℃, the drying rate of the alfalfa stem with a crushing ratio of 0.245 7 is close to that of an alfalfa leaf. At a drying temperature of 100 ℃, the drying rate of the stem of 50 millimeter long with shrinkage of an alfalfa leaf is the largest in the short six leaves attached is close to that of a single leaf. The axis direction.
Abstract: In order to solve the poor robustness of parameters in a vector control system, a new kind of control scheme for induction-motor variable-frequency speed regulation systems was proposed based on the theory of auto-disturbances-rejection control (ADRC). In the control scheme, the change in rotor time constant was regarded as the inner disturbance of the flux subsystem, the effect of the change in rotor flux linkage amplitude and that of load as the inner and exterior disturbances of the rotate speed subsystem respectively, and the extended state of an extended state observer (ES()) was used for estimation and compensation. The control scheme can solve such problems as the effect of time-varying parameter on the decoupling performance of a vector control system and the contradiction between speediness and stability in common vector control systems. Simulated results indicated the rationality and validity of the scheme abovementioned.
Abstract: The watershed algorithm leads to over-segment when it was used to segment an infrared image. An adjustable bias-anisotropic diffusion filter based on CNN-PDE for smoothing an infrared image was studied. In order to remove the residual noise which can not be smoothed by filter, the smoothing coefficient and constrain coefficient were used to threshold the gradient image. The result of watershed segmentation of a practical infrared image shows the presented method can restrain over-segmentation effectively.
Abstract: The paper proposed a dynamic time warping (DTW) indexing and similar matching method of time series based on discrete wavelet transform, which reduced the dimensionality of time series by discrete wavelet transform and constructed multi-dimensional index structure by R*-tree. The DTW lower bound and its discrete wavelet transform of query sequence were computed to form a query super-rectangle, thus the similar matching in original space based on DTW was converted to that in wavelet transform space based on Euclidian distance. It was proved that the method guaranteed no false dismissals and proposed the range query algorithm and nearest neighbor query algorithm. The result showed that it was a higher query precision and lower computing cost.
Abstract: This paper studied the design of the optimum preview controller used for a class of state-delay systems. Difference method was first introduced to translate the time-delay system into a common system without time-delay, and then the theory of preview control for a system without time-delay was used to design the controller. The sufficient conditions for the designed controller were proposed. The efficiency of this feedforward compensation method was testified through an emulational example.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
