Abstract: This paper elucidates the theory and proclice of opening mainteance insoft and broken rocks. Its main peints are as follows. (1) The radical Cause of failure of viarous type of supporting structure in soft and broken rocks in Jin Chuon Mine before 1978 has been found to be that the stabilizing problem of rheological rocks around openings was simply regarded as a structure problem of conventional supporting. (2) The soft and broken rocks in Jin Chuon Mine is a kind of rheological materials which may readily become loose material. So it is necessary to use secondary supports for the openings in such rocks. (3) The ground prossure around the openings in soft and broken rocks in Jin chuon Mine is recognized as a deformation pressure of rheological amaterial. (4) The basic regularity of ground pressure in Jin Chuon Mine is determined there are two compressed and compacted regions,one slack region, and one broken region around the openings in 12 meters deep. The compressed and compacted regions are bearing circles and play a critical part in stabilizing the openings around. (5) An information design method, field supervision and control method is used in Jin Chuon Mine. (6) The supporting principles and design methods of openings in softs and broken rocks in Jin Choun Mine are put forward. It is important to us-information design method to make support property and construction tech-nic to fit deformation condition of rocks around the opening.lt is also important to restrain rock deformation and slabilite the apening through anal ysis of regularity of ground pressure in accordance with different rock properties and ground perssure type.
Abstract: Contribution of N.M. Chuiko to the development of the coexistence theory of slag structure. The insufficiency of the previous demonstration for this theory. Further fundamental facts confirming the coexistence theory of slag structure (the facts of crystal chemistry, the difference in electric conductivity of various slags, the liquid miscibility gaps of MeO-SiO2 bin-nary slags,the peaks on the temperature composition diagram of MeO-SiO2 binarg slags, the viscosity-composition diagram of CaSiO3-CaF2 system, the relation between standard free energy of formation of silicates and mass action concentrations). some examples about the use of the above mentioned theory (eqnilibrum between FeO-Fe2O3-SiO2 and H2O + H2,CaO-SiO2, distribution of sulfur between CaO-MgO-FeO-Fe2O3-SiO2-S and liquid iron).
Abstract: Medium manganese white cast iron is an abrasion resistant material investigated and developed to suit our own national resources and production conditions.It had been successfully used to manufacture slurry pump volute, classifier blade, etc.in mining industry for its excellent cost effectiveness and availability. In this paper, basing on the wear test results of medium Mn white cast iron of different compositions that had undergone different heat tratments, the effect of structure on abrasion resistance of this material in relation to the wear mechanisms of different classes of abrasive wear was discussed. Low stress erosion wear tests were done in sand mixing pan and rubber wheel wear testing machine.Martensite-carbide structure of high hardness is most wear resistant.Boron addition to medium Mn white cast iron can increase the microhardness of carbide and bulk hardness still further but it lowers the strength and toughness of the material.Only suitable addition of B is be-nefial.This is related to the macro-erosion mechanism of wear. High stress grinding wear tests were done in pin tester and three body rolling wear tester.The abrasion resistance is related to both hardness and toughness of the material.Matrix harness sometimes has decisive effect.The combined alloying with Cu Cr and Mo was used to obtain high hardenability and high microhardness of the structural comstituents.Retained austenite lowering the matrix hardness is not desirable because of the microcutting mechanism in this class of abrasive wear. Finally, repeated impact wear test was done by a reciprocating punch impinging on the surface of a reveolving ring specimen with quartz sand flowing between the contacting surfaces.The abrasion resistance depends very much on the tough-ness of the material.Low carbon content and rare earth modification to improve the morphology and distribution of carbide are both advantageous.The deformation wear mechanism predominates in this class of abrasive wear. Thus we can conclude that the appropriate structure of a wear resistant material depends on the class of abrasive wear and the wear mechanisms involoved.
Abstract: This paper presents the possibility of making nodular graphite cast ironbyinjection of rare earth alloys instead of magnesium as nodularizer to themolten iron with different sulfur content.Rare earths are as excellent no- dularizers as magnesium, since the injection method has improved the kinetic conditions of the nodularizing reaction. The range of rare earth residue in nodular graphite cast iron and the treatment method for different nodula-rizers are discussed preliminarily in this paper.It is proposed that injection is a suitable method for producing rare earth nodular graphite cast iron.
Abstract: In this paper the main concepts and fundamental ideas of exergy analysis relating to the cxcrgy balance of industrial furnaces are presented A few of the concrete problems about exergy analysis are discussed, and a set of Comparatively complete formulas applied fo exergy balance of cotinnuous reheating furnaces are suggested. In order to compute the distribution of exergy losses within the industrial furnaces, the concept about quality of energy is introduced into exergy balance computations, and then a physical model of reversible heat transfer is given for those type of furnaces within which combustion and heat transfer exist,so the formulas applied for computation of the exergy losses distribution within the furnaces are established, In the given model, the fundamental principles of exergy analysis, and the method about thermodynam-ic state functions are used, and a reversible heat transfer module in relevance to the thermal characteristics of the furnaces is constructed for evaluating the degree of irreversibilitg of actual heat transfer processes-The physical meaning of the model is clear, and with its help, problems about distribution of irreversible exergy looses due to heat transfer within the furnaces are solved.
Abstract: In this work, the gas-liquid two phase fluid flow and the recirculating flow field in the bottom blown argon stirred bath are studied by means of experiments carried with physical model together with numerical solutions of the mathematical model. The mathematical model consists of the turbulent flow mean vorticity transport equation and stream function equation. K-ε turb-ulance two equation model, the pure buoyance madel and the boundary conditions, The mathematical model is numerically solved implicitly using methed for solving recirculating flow problems developed by prof, Spalding, so that the flow pattern and dislributions of velocity,turbulence kinetic energy, turbulence kinetrc energy dissipation rate, vorticity, the turbulence viscosity, the density and the gas void fraction ratio are obtained. Velocity distribution computed agree well with those measured by laser Doppler anemometer, the computed flow patterns together with the position of the centre of the recirculation flows are in agreement with those obtained by photograpies taking from flow visualization. It shows that, the mathematical model together with its method of solution used arc acceptable for predicting the velocity field in domain of the problem worked, and this work therefore is of practical significamce.
Abstract: The cyclic stress-strain responce and microstructures(TEM) were studied in LCF samples of 15Cr-27Ni-1.8Ti-Fe alloy. The strain control LCF tests were performed at 600* under two different wave mode:R=-1 and fixed eeeemax. Comparing the results of these two kind tests, the detrimantal effect of average tensile stress was proved. This was comcerned with the influenceof tensile stress on the movement of dislocations and the fromation ocracks. The observations of dislocations structure indicated that during the cycling both mechanisms causing cyclic hardening and cyclic softening were taking place. Cyclic strain led to generate the stress-field at the interface of γ and γ' phases first. As a result of increasing stress field the dislocations were created.The density of dislocation was further increased by the move, ment of dislocations themself. The interactions between dislocations and γ particles degenerated from pair dislocation cutting γ' particles to single dislocation cutting γ'particles. It led to form more faults and APB'S, and the γ' particles became propressively harder to shear and ultimately led to dislocations looping around particles. A typical dislocation structure of persistant slip hand, laddie-like stracture was seen asasatureted dislocation structure in the slip band,and the more laddie-like structure formed, the more cyclic softening happened. The slip band extended to grain boundaries and twin boundaries, The grain diclocations interacted with boundaries, and led to complex boundary dislocations structure the density of dislocations near grain boundaries andtwin boundaries was much higher than others since the boundaries can actedas the barrier and dislocation generator. This would cause to form grainboundary cracks and twin boundary cracks.
Abstract: This paper deals with the influence of metal and alloy on the measurement of wetting angle of microdot artificial diamond by means of microscopy and scanning electron microscopy. The influence of noncarbide forming elements of untransition group (Cu, Sn, Pb, Al, Ag) and Cu-Sn alloy on the wetting ability of microdot artificial diamond is also studied.In addition to this, the influence of adding carbide forming element of tra-nsition group Ti on the wetting angle is also discussed.lt is shown that the wetting angle decreases with the increase of large amount of Ti.
Abstract: Baysed on the investigation of experimental data in the D. D. D semi-continuous bar mill φ250mm×6, the following works have been studied: 1.The accuracy of product has been analyzed statistically.The mechanism of forming a bigger head and tail, and the fluctuation with high frequency in dimension along the product length has been made clear by the method of simulation. 2.The actual tension level between stands is estimated by the current data of D. C motor. Thus, it is denoted that in order to further improve the product accuracy and rolling process stableness, the free tension control technique should be developed.
Abstract: This paper presents an approach to the enveloping of biparametric surf-ace family and the quadratic enveloping of single-parametric surface family. Both are expressed in terms of implicite or parametvic equations. A simple method fov solving the quadratic enveloping through solving of a bi-param-etric surface family and the equivalent enveloping conditions are established.
Abstract: In this paper, the method of nonlinear programming is used to design the Work-mechanism of scooper loaders. The mathematical model contains nine design variables, thirty-four constraint equations and one comprehensive objective function consisting of the parallelism of scoop upward motion and the rotating force of hydraulic cylinder for running scoop. The above mathematical model had been applied for computation to the domestic ZLD-40 type scooper loader by means of SUMT and interesting re-sutls were obtained. The computed resutls confirms the crrectness of the above mathematical model. The design quality and operation effectiveness of the work-mechanism pf the scooper loader could be improved by this method.
Abstract: In this paper,empirical formulas of relative interference quantity, δ,and heat expansion coefficient,αF,are obtained by data processing of whole ring experiment.They are important parameters in the rings design.The paper also describes the application as well as the accuracy of them by examples.
Abstract: In this paper the author derived a set of basic equitions of sonic line theorelically according to the dislributiv eparameters, built a digital simulation model of expantion type mufflers, and developed a simlation method. Therefore information for designing mufflers and for prediecting the value of noise-reduction is provided.
Abstract: HASH TABLES are widely and efficentey used for designing a variety of software in Computers, and in special for data processing and data base system. The efficency of the advenced Searching technology-the average Searching time on the table, A is discussed in theory in this paper. Two theoretic formulas is given and a random on-line test is done using the Computer M-150. The theoretic correctenss is proved by a lot of result obtained.
Abstract: The volumetric masstransfer coefficientnts in the decarburizing kinetic model arc considered as stochastic coefficients in this paper, based on earlier work[1] The theoretical expression of solution-process is obtained under some assumptions, and the moment functions are calculated.
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
