Abstract: Aimed at the mining environment image of a seabed nodule-collecting vehicle,the detail of the image was enhanced by subsection linear transformation,and the interferences of suspensions were removed with a median filter.The profile of terrains and obstacles was extracted by an anti-noise gradient operator in morphology,and the rate of change of surface brightness was computed by subsection-linear fitting.According to the feature of the brightness variation,the type of obstacles was estimated,and the profile was detailed and linked by self-adapting morphology.Based on the image information of obstacles,the distance,height and width of the obstacles were computed by projection transformation.Close analysis of land images demonstrated the reliability of computing such parameters as position,height and gradient.This method not only reserves the profile information,but also improves the anti-noisy ability and the anti-interconnection ability,detects the deep-seabed terrains and obstacles efficiently,and works out the position and figure efficiently,so it can be used to provide reliable data for the information fusion technology of the obstacle-avoiding system in a nodule-collecting vehicle.
Abstract: The construction technology of cumulative blasting and the mechanical behavior of sealing materials were analyzed for the gas drainage sealing technology of coal bed deep-hole cumulative blasting.It is shown that blast hole diameter and sealing material properties are the main factors which influence sealing length.After comprehensive analysis of blasting safety,drainage technology and constructional conditions,the reasonable sealing length of cumulative blasting is considered to be in the range of 7.5 to 10.0m.Finally,the feasibility of coal bed deep-hole cumulative blasting sealing technology was tested with the 14121 and 24021 working faces in Jiulishan Coal Mine of Jiaozuo Coal Group as an example.
Abstract: Large concentration of coal dust exists in the fully mechanized workface due to high dust production and low dust removal efficiency.Based on fluid dynamics,the gas-solid two-phase flow theory and the jet theory,the dust migration mechanism and distribution in a roadway under far-pressing-near-suction ventilation were studied with the FLUENT software.The effects of ventilation parameters such as the air quantity of forced ventilation,the ratio of blowing to suction and the position of the force-ventilated outlet on the concentration and distribution of the dust were analyzed comparatively.A forced ventilation shunt mode was proposed,and its dust removal efficiency was simulated.
Abstract: The rheological characteristics and parameters of the filling slurries of 69% to 81% in mass fraction were tested with a four-bladed vane rotary rheometer taking unclassified-tailings filling paste as a research object.Based on the Herschel-Bulkley model,the rheological models were derived from regression at shear rates of 0 to 120s-1.It is shown that the rheological models exhibit yield-pseudoplastic for the filling slurries of 69% to 81% in mass fraction and Bingham plastic for the filling slurries of 81% in mass fraction.There is a good linear relationship between the flow behaviour index n and the mass fraction of filling slurries,and the flow behaviour index n increases with the mass fraction of filling slurries increasing.Finally,the threshold mass fraction of the paste is 80.91%.
Abstract: In order to study the excavation effect in underground engineering,multiaxial tests were adopted on rock thick-walled cylinders.First,high axial pressure,confining pressure and inner pressure were applied on the cylinder samples.Then,inner and confining pressures were unloaded in time order.The experimental results show that a main ringlike failure surface forms in the thick wall of the cylinders.This kind of ringlike failure phenomenon,which is different from the result of failure initiated at the inner surface for the cylinders under high pressure based on general elastic-plastic analysis,has not been reported in published literatures so far.This experimental result is similar to intermittent zonal fracturing characteristics of deep underground roadways after excavation.
Abstract: Bioleaching of chalcopyrite with two different types,pyrite type and porphyry type,was compared.It is shown that there is a great difference in leaching efficiency.After 48d,the copper leaching rate reaches 46.96% for the pyritic chalcopyrite,while it is 14.5% for the porphyry chalcopyrite.Based on the analysis of Fe2+,Cu 2p spectra on the chalcopyrite surface and deposit characteristics,a moderate amount of Fe2+ can promote bioleaching of the two kinds of chalcopyrite,but their optimal dosages are distinct.Different products appear on the surfaces of leached residues,and there is a copper-rich layer on the porphyry chalcopyrite,which hinders a greater copper extraction.Compared with the crude ore,Cu peak shift to lower binding energies was observed,following the leaching mechanism suggested by Hiroyoshi et al.the difference in bio-leaching between them is dependent on the integration of many factors such as metallogenic rock,wall rock,associated minerals and elements,metallogenic temperature and pressure.
Abstract: The dissolving and crystallization process of zinc oxide in an alkalescency system like the hydrometallurgical process of alumina was discussed according to the equilibrium phase diagram of the Na2O-ZnO-H2O ternary salt-water system at 25,75 and 100℃ by the isothermal solubility method.The results show that the circulation of zinc oxide can be realized by separating zinc oxide through diluting if the mass fraction of sodium oxide is below 34% at 100℃.But for the equilibrium system in which the mass fraction of sodium oxide is above 29% at 100℃,it is also possible to separate sodium zincate by cooling.Sodium zincate can easily decompose into zinc oxide by diluting with water,and the circulation of zinc oxide is realized in this concentration range of sodium oxide.
Abstract: The influences of CaO on the formation and growth of iron whiskers and their mechanism in the reduction of iron oxide under CO atmosphere were studied.In situ observations on the development of iron whiskers were carried out using a stereo optical microscope and a hot stage under CO atmosphere.The reduced samples were analyzed by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS) and Fourier transform infrared spectroscopy(FTIR).It is indicated that the formation and growth of iron whiskers proceed in the stage of FeO being reduced to Fe and CaO has a negative effect on the reduction of iron oxide.When the mass fraction of CaO mixing into the sample is more than 8%,iron whiskers can not be observed.Therefore,controlling the amount of CaO mixing into the sample can inhibit the formation and growth of iron whiskers and reduce ore grain agglomeration.
Abstract: As for the IF steel making process of BOF+LF+RH+CC,the free oxygen content drops to a minimum level after deoxidization and LF refining,and right before RH decarburization.The RH decarburization reaction of steel with extreme low oxygen can be divided into four stages in terms of the apparent decarburization rate constant.Differed from traditional three-stage RH treatment,a transitional stage with medial decarburization occurs between the low and high decarburization stages.Based on the regular solution model,a decarburization model was developed to forecast oxygen content in the steel and FeO content in the top slag.It is found that there is no oxygen transferring between molten steel with extreme low oxygen and the top slag before RH blowing oxygen.After RH blowing oxygen,the oxygen content increases linearly,then oxygen transfers from the molten steel to the top slag which has a lower oxygen potential,and the FeO content increases consequently.Though the FeO content at the end of RH refining rises higher than the initial content,it is still fairly low enough to avoid reoxidation by the top slag to molten steel.
Abstract: The effect of strongly reduced refining slag with different basicities and Al2O3 contents on non-metallic inclusions in molten steel was investigated through the slag-metal equilibrium at 1 600℃.When the slag-metal equilibrium is reached,the mass ratio of CaO to SiO2 in refining slag is from 1.9 to 4.5,and the mass fraction of Al2O3 is from 21% to 33%.Non-metallic inclusions in steel are mainly the spherical CaO-MgO-Al2O3-SiO2 system with size smaller than 5 μm.The composition of refining slag has a great effect on inclusions.Inclusions mainly distribute in the low melting point region of the CaO-MgO-Al2O3-SiO2 quasi-ternary phase diagram with stable content of SiO2 between 1 400℃ and 1 500℃.With the basicity of refining slag increasing and the Al2O3 content decreasing,part of inclusions gradually deviate from the low melting point region and the total number of inclusions decreases.When the mass fraction of Al2O3 is 21.22% and the basicity of refining slag is 3.27,lots of inclusions distribute in the high melting point region and the total number of inclusions is the smallest.
Abstract: A Mo-containing X80 high-deformability pipeline steel was processed by TMCP rolling and two-stage controlled cooling in laboratory.The effects of cooling conditions on the microstructure and properties of the steel were investigated by scanning electron microscopy(SEM) and transmission electron microscopy(TEM).It is found that the microstructure of the steel processed by two-stage controlled cooling is ferrite-bainite dual phase.As the start temperature in accelerated cooling comes down,both the strength and yield ratio decrease and the uniform elongation(uEl) increases with the ferritic volume fraction increasing.As the finish temperature in accelerated cooling becomes lower,the amount of martensite-austenite(M/A) constituents in bainite decreases and the M/A islands are much finer and more uniformly dispersed.The strength changes little but the uEl increases significantly.It is considered that uEl is closely related to M/A constituents in bainite when the ferritic volume fraction is constant.Finely and uniformly dispersed M/A islands can increase the value of uEl by increasing the work hardening rate and delaying the onset of necking.When the accelerated cooling starts at 690℃ and finishes at 450℃,the ferritic volume fraction is about 23%,the grain size is approximately 5 μm,and the average grain size of M/A islands is approximately 1 μm.The uniform microstructure provides good combination of strength-ductility properties.
Abstract: Low cycle fatigue(LCF) experiments were carried out under strain control at room temperature on X12CrMoWVNbN10-1-1 steel for rotors used in ultra-supercritical turbines.Some LCF parameters of this material at room temperature including Ramberg-Osgood parameters,Manson-Coffin parameters and transformation life were obtained by fitting the cyclic stress-strain curves and strain-life curves.The peak tensile stress,the peak compression stress,the unloading elasticity moduli of tension and compression,and the area of the hysteresis loop in the LCF initial stage and finial stage were analyzed by comparison.The stress changes corresponding to LCF controlled by different strain amplitudes were discussed.
A novel material Mg-4%Ni-1%NiO for hydrogen storage applications was fabricated by mechanical milling at cryogenic temperature(cryomilling).The effects of ball milling time on the structure morphology and the hydrogen storage performance of the newly developed materials were investigated at cryogenic temperature.The phase structure and surface morphology were analyzed by X-ray diffraction(XRD) and scanning electron microscopy(SEM).The hydrogenation and dehydrogenation characteristics were studied by a pressure-composition-temperature(P-C-T) apparatus.It is shown that the phase structure of the materials remains almost unchanged even after 2,4,and 7h of ball milling,respectively and only a small amount of Mg2Ni forms.However,a sharp depreciation in the average particle size of the alloy was observed with the ball milling time prolonging.Furthermore,there are Ni and NiO particles in the Mg matrix.In company with the changes above,the activation performance and absorption performance of the materials are gradually improved.The materials ball-milled for 7h can reach the maximal desorption rate after one activation,the onset desorption temperature is 60℃,the compounds exhibit a hydrogen storage capacity of 6.4%(mass fraction) at 200℃ under the hydrogen pressure of 4.0 MPa,and they can absorb 80% of their full hydrogen capacity in 60s and 90% in 10 min.As the ball milling time is prolonged to 4h,the performance of the materials is stable,the onset desorption temperature is 310℃ under 0.1 MPa,and the materials are able to desorb about 80% of their full hydrogen capacity in 500s at 350℃ under the hydrogen pressure of 0.1 MPa.
Abstract: ungsten/iron functionally graded materials(FGM),in which the volume fractions of tungsten are 0%,25%,50%,75% and 100% respectively,were produced by resistance sintering under ultra high pressure.The effects of components and preparation parameters on the microstructure and mechanical properties of W/Fe FGM were analyzed.It is shown that W/Fe FGM,whose relative density reaches more than 98%,can be obtained at a pressure of 9 GPa and an input power of 11 kW for 60s so that the elemental composition distribution is in agreement with the designed.
Abstract: The effects of sealing atmosphere,sealing temperature,sealing time,oxides' type and thickness on porosity and glass sputtering were investigated by measuring the porosity and the maximum diameter of gas bubbles in the glass insulator and observing the glass sputtering state on the surface of kovar alloy under various process conditions.It is indicated that there is a relationship between the porosity of the glass insulator and the glass sputtering grade on the surface of Kovar alloy.The chemical reaction between Fe3O4 on the surface of Kovar alloy and SiO2 in glass is an important source of porosity in the glass insulator,and it is also an influence factor of glass sputtering.Sealing atmosphere and oxides' thickness are the most important factors for porosity and glass sputtering.The recommended conditions are that FeO is formed on the surface of Kovar alloy and its thickness is about 1 μm,the sealing temperature is about from 950 to 980℃ and the sealing time is from 30 to 40 min in the real production atmosphere.
Abstract: A elastic-plastic transform formula between crack mouth opening displacement and loading-line crack opening displacement(COD) for straight-notched compact tension(CT) specimens was deduced on the basis of the rigid rotation hypothesis and the work equivalence principle.Cr2Ni2MoV steel was employed to verify the validity of this formula experimentally.As a result of elastic-plastic finite element analysis,the rigid rotation assumption is completely proved.The rotation center of a straight-notched CT specimen is near the crack tip,and has little effect on the material constitutive relationship;consequently,the rotation radius R of the specimen is only related to the ratio of crack length a to specimen width W.The finite element analyses and experiments indicate that more accurate results of plastic work for straight-notched CT specimens may be obtained if using the elastic-plastic COD transform formula.
Abstract: By using a type of single specimen method for determining ductile fracture toughness based on the load separation principle,the normalization method and the load separation parameter SPb method were investigated with a steam turbine rotator steel Cr2Ni2MoV.It was found that in the normalization method the blunt line equation used to blunt correction had an influence on the determination of J resistance curves within a limit crack extension.A modified separation parameter SPb method was proposed to eliminate the effect of reference blunt cracked specimens on the original separation parameter SPb method.The blunt corrected initial crack length and final crack length were recommended to use as two calibration points simultaneously to obtain more reasonable measurements of instantaneous crack length.The J resistance curve derived from the modified separation parameter SPb method is higher than that obtained by the normalization method within a limit crack extension;however,the two curves agree very well within a larger crack extension.The value of conditional crack initiation J-integral JQ from the normalization method is more conservative than that estimated by the modified separation parameter SPb method.
Abstract: A new kind of helical gear with asymmetric involute teeth was proposed in order to improve the transmission performance and bearing capacity.A rack cutter was designed for manufacturing the gear.The parameter relationship between the rack cutter and the gear was analyzed.Tooth profile equations of the gear's transverse section,normal section and axial section were discussed and a helicoids equation along the axial was derived.The meshing theory of the gear pair was studied,and the internal and external meshing coordinate transition matrices of conjugate tooth profiles for the gear were deduced.Based on the parameter relationship of the gear,three-dimensional software was used to build a parameterized three-dimensional model of the gear,which verified the correctness of the mathematical model and theoretical analysis.
Abstract: The yield strength and tensile strength of high-grade steel casings such as Q125,V140 and V150 were obtained by indoor experiments under high temperature conditions.The strength reduction factor was introduced and its equation applicable for the high-grade steel casings at high temperature was regressed from the experimental data.The strength reduction factors at 150℃ and 200℃ were given for convenient applications in oilfields,adopted by Chinese Petroleum and Natural Gas Industry Standards and applied to the design of high temperature casing strings.Design verification and safety evaluation of deep-well casing strings in western China based on the experimental results and the regression formulas show that the experimental data have good versatility to meet the requirements of field casing design.The yield strength and tensile strength of the high-grade steel casings decreases greatly with increasing temperature,and the decrease rate of yield strength is greater than that of tensile strength.It is suggested that the influence of temperature on the material properties of the high-grade steel casings should be considered during the design of high-temperature well casing strings.
Abstract: A permanent magnet frame based on ‘magnetic sieve’ effect for oxygen enrichment from air was theoretically studied.In the magnetic field space formed by two square permanent magnets,the central magnetic flux density and the capability of intercepting oxygen molecules increase with the thickness of magnets increasing,but the increase speed slows down.The enhancement of magnetic flux density by increasing the thickness of magnets is not infinite.For the specified thickness and length of magnets,the magnetic flux density and magnetic uniformity across width in the magnetic field space decrease with the width of magnets increasing.The magnetic uniformity required by the characteristic of the ‘magnetic sieve’ can be satisfied only when the thickness-to-width ratio of permanent magnets is larger than 1.For the given thickness and width of magnets,the magnetic flux density in the magnetic field space is less influenced by the change in length of magnets.Therefore,appropriately increasing the length of magnets can prolong the flow time of air and improve oxygen enrichment by the ‘magnetic sieve’.
Abstract: A sensitivity compensation method was proposed for anisotropic magnetoresistive(AMR) sensors based on sensitivity online recognition.An experimental study on this method was carried out with an AMR sensor BKMC-21 developed by University of Science and Technology Beijing.The experimental results show that the magnetic field output of BKMC-21 without sensitivity compensation varies greatly after switching the power supply on.It takes about 30 min to be stable,and during this period the sensitivity variation is over 20%.The magnetic field output of BKMC-21 with sensitivity compensation is stable,and the sensitivity variation is less than 2% after switching the power supply on.It can be concluded that the sensitivity compensation method proposed for AMR sensors based on sensitivity online recognition can effectively solve the sensitivity variation problem of magnetometers.
Abstract: A new hybrid structure arranging a double-layer shell between truss strings was proposed in the project-roof design of the Exhibition Center in Erdos Dong-sheng Sports Center.The new structure system not only meets the demand of adapting to an irregular large-span roof,but also increases the structural stiffness and stability.Model examples close to the actual project was designed.The effects of sag-to-span ratio,initial prestresses and the numbers of struts on the static and dynamic behaviors and the steel consumption of the integral structure were fully analyzed by concerning the integrate model.Based on the research result of model examples,the irregular roof of Erdos Dong-sheng Exhibition Center was designed.Besides,the design of the pre-stressed cable is difficult and critical,and a detailed method and the corresponding reference to adjust the pre-stressed cable were provided.
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
