A new theory for inverse problem of wave equation, that is, the union method for scattered wave extrapolation and velocity imaging, is proposed in this paper. This method is very different from the classical wave extrapolation for migration, because we relate directly the scattered wave extrapolation to velocity inversion. And also this method is different from any linearized inverse method of wave equation, because we needn’t use linearized approximation. Because of this, the method can be applied to strong scattering case effectively (i. e. the value of scattered wave is not small, which can not be neglected). This method, of course, is different from nonlinearized optimum inverse method, because in this paper, the nonlinear inverse problem is turned into two steps inverse problem, i. e. scattered wave extrapolated and velocity imaging, which can be solved easily. Hence, the problem how to get the global optimum solution by using the nonlinearized optimum inverse method doesn’t bother us by using the method in this paper.

A novel spray deposition technology with the characteristics of multi-layer deposition, the combination of forced external cooling and internal water-cooling of the substrate was developed. Compared with the conventional spray deposition technology, the novel technology exhibits the specific advantages, including larger solidification rate, higher dimensional precision, and ease to manufacture large preforms. The law of multi-layer spray deposition was studied, and Al-Fe-V-Si alloy with good high-temperature mechanical properties and 6066Al/SiC_p composites with excellent room-temperature mechanical properties are prepared by this novel technology.

Organic-inorganic composite biomaterial (HA-TCP-BMP) used as bone substitutes and the fabrication process are described in this paper. The quantitative calculation ofβ-whithokite presented in sintered material is about 14%–18% and the ratio of Ca/P is about 1.61. The influences of the composition and structure on the bone forming properties and biologic effects are discussed. Meanwhile, the results of clinical application of the composite materials are viewed. The research results show that the composite material can be completely degradated in controlle time and at the operation site new formed bone can fully replace the implanted material.

The effect of carbon content on the morphology of martensite in carbon steels has been studied in depth. It is found that not all the packet martensites obtained in carbon steels quenched from elevated temperature are lath martensite. The packet martensite obtained thus should be divided into two categories: packet thin plate martensite (i. e. lath martensite) and packet plate martensite. The former is only found in low carbon steels, the latter mainly in medium and high carbon steels. The morphology of martensite in steels with different carbon contents has been researched in detail using optical microscopy, SEM and TEM. A new criterion is proposed for identifying the category of martensite. Based on this new criterion, it is found that as-quenched steels withC_c⩽0.2% contains lath martensite; that with 0.2%<C_c<0.4% contains a mixture of lath and plate martensite. The structure of as-quenched steels withC_c⩾0.4% is completely of plate martensite. The curve of the relative volume percentage of martensite without internal twins versus carbon content has been redetermined. Finally, the misinterpretation of experimental results by previous investigators is analysed.

The microstructure together with the formation and growth of reaction phases in the interfacial diffusion zone of the explosive cladding TA2/A3 has been investigated by means of OM, SEM, AES and XRD techniques. When the specimen annealed at temperature under theβ-Ti→α-Ti transformation, i. e. below 1 173 K, only TiC forms along TA2 side of interface and hinders the interdiffusion of Fe and Ti atoms, thus Fe₂Ti or FeTi is unable to occur. While heated up to the transformation temperature ofβ-Ti, e. g, over 1 223 K, the parabolic growth of intermetallic compounds of Fe₂Ti and FeTi with layer structure may form intergranularly and the formation ofβ-Ti orβ-Ti+α-Ti structure at the Fe enriched side of TA2 and the martensitic transformation products at the Fe-depleted side are observed owing to the diffusion of Fe. Furthermore, the growth ofβ-Ti transformation layer is revealed to follow the parabolic rule.

The fracture toughnessK_Ic, the tensile deformation and fracture behaviors of different microstructures ofγ-TiAl based alloy, Ti-33Al-3Cr-0.5Mo] were studied at room temperature. It is found that theK_Ic value is lower in the duplex microstructure, and increases with the increase of vol pct of the lamellar microstructure, and that the full lamellar has the highestK_Ic value. Cleavage was the dominant fracture mechanism in the duplex microstructure material. In contrast, for the full lamellar microstructure the high anisotropy of deformation and the large strain discontinuity at grain boundaries resulting in decohesion of grain boundaries are the main fracture processes.

The citrate gel of (Bi, Pb), Sr, Ca and Cu and the (Bi, Pb)-Sr-Ca-Cu-(O, F) superconductor were prepared using citrate as the organic complex agent and 2-ethyl hexanol as the dehydrating agent. The starting material was a high-purity nitrate solution containing the desired ions in the appropriate atomic ratio. The optimum temperature and pH to obtain the homogeneous gel precursor were estimated. IR and DSC were employed to study the thermal decomposition and the calcination of the precursor material. After the calcined powder was sintered, a nearly single-phase (Bi, Pb)₂Sr₂Ca₂Cu₃O_x superconductor with the transition temperature 105 K was synthesized. The effect of the doping of Pb and F was also studied in the paper.

The iron rhenate was compounded by chemical method, which may be generated during wear process of Fe-Re alloys at elevated temperature. The friction coefficient of iron rhenate has been determined by a pin-on-disc device. The results show that iron rhenate plays role of lubricating at RT-600 °C. The lubricating behavior is related to the matching pairs. The hardness of the materials of matching pairs, compatibility of iron rhenate with materials of matching pairs and surface roughness of disc affect the lubricating behavior of iron rhenate mostly. The principle of matching pairs is proposed.

The change of stress and temperature in the conform forming process has been studied. On the basis of the law of momentum, the law of momantum moment and the law of energy conservation, the governmental differential equations of stress and temperature in the conform metal forming process have been derived, whose definite conditions are given by material mechanics, elastic machanics and plastic mechanics. The analytic solution of these equations has been successfully obtained and as a result, the solid foundations and scientific guide for the further development of this prospective metal processing technique have been established.

In the paper, the problem of H_∞ decentralized state feedback control for large-scale systems is described. An algorithm is proposed which uses the method of a feasible direction matrix. The algorithm only requires the solution of an algebraic Riccati equation (ARE) and makes the H_∞-norm of the closed-loop transfer function matrix from disturbance inputs to controlled outputs less than a given constant which ensure the stability of the overall controlled system at each iteration. The given example shows that the convergence of the algorithm is satisfactory.

Unsupervised learning plays an important role in the neural networks. Focusing on the unsupervised mechanism of neural networks, a novel generalized goodness criterion for the unsupervised neural learning of visual perception based on the martingale measure is proposed in the paper. The differential geometrical structure is used as the framework of the whole inference and spatial statistical description with adaptive attribute is embedded in the corresponding nonlinear functional space. Consequently the integration of optimization process and computational simulation with the Neo-Darwinian paradigm is obtained. And the generalization of the guidance for the evolutionary learning in the neural net framework, the convergence of the goodness and process of the evolution guaranteed by the mathematical features are discussed. This criterion has generic significance in the field of machine vision and visual pattern classification.

A new technological process for production of paratungstate ammonium from low grade tungsten concentrate with a high content of calcium and impurities has been studied. The experiments show that average tungsten leaching efficiency of more than 96.92% can be obtained with a low NaOH consumption by using the mechanical activating caustic decomposition, and the content of main impurities (P, As, Si) in Na₂WO₄ solution obtained is competitive with that from standard wolframite concentrate by traditional caustic decomposition. After recovering caustic soda by crystallization, impure Na₂WO₄ solution is changed to (NH₄)₂WO₄ solution by ion exchange method. Molybdenum may be removed from (NH₄)₂WO₄ solution by new ion exchange method. Finally, paratungstate ammonium of high purity is obtained. This technology has the advantages of short technological process, high recovery of tungsten, high economic and social benifits.

In this paper, the structure and function of the IDSS in the operation process of electric furnace for cleaning slag are presented and the fuzzy neural network decision model (FNNDM) in the IDSS is specially suggested. The IDSS possesses self-learning and adaptive properties, and has been used for managing and analyzing the optimal operational conditions since June 1992. Electric energy consumption has been reduced remarkably and the coefficient of recovery of cobalt and nickel has been increased.

Leaching of low-grade refractory tungsten ore was carried out through mechanical activation. The effect of temperature, amount of Na₂CO₃, addition of NaOH, ratio of liquid to solid and leaching time on the recovery of WO₃ was studied. The WO₃ recovery upto 96%–99% has been achieved when the tungsten ore was digested by soda not more than three times stiochiometric amount at 185–195 °C for 1.0–2.0 h. The WO₃ recovery can increase 10%–15% compared to that of conventional soda autoclave process.

The influences of instrumental errors, measurement errors, and the fluctuation of refraction angles,etc., on the observation accuracy of vertical angles are analysed. A new target used to observe the vertical angle was designed. Some measures are suggested to reduce the errors in observing vertical angles. They are proved to be effective by experiments.

The restriction ofK-B averaging method is discussed and asymptotic solution of the weakly nonlinear and forced oscillationu″+ω₀²u=εkcosωt−εu³ is obtained by Struble technique. The conclusion about this oscillation derived with other method is discussed. The results show thatK-B method will break down whena andθ in the zeroth solution of above eqation are not slowly varying functions of timet. The stationary solution of weakly nonlinear oscillation,u″+ω₀²u=εkcosω(ε)t-εu³ is also analysed.

This paper presents a new transaction method in terms of which deals are concluded by competitive prices, and indicates its design on multi-user platform, especially the research of synchronization and vieing for powers. The system was programmed with SCO FOXBASE 2.10, C language and Shell. The result of nearly two year’s use proved that the transaction method and its accomplishments are all practicable.

Flotation technology design includes data calculating and flowsheet drawing. To implement data calculating, relative matrix is used to express the flotation flowsheet, special mineral processing models and optimizing mathematical models have been used. The “binary tree” principle has been used to demonstrate the flotation flowsheet structure, and the coding principle according to the order of preorder traversing to “binary tree” is determined for the implement of the flotation flowsheet drawing. As a result, the computerization of flotation technology design was completed. Design principles, models and application of the software are discussed in this paper.

The algorithm proposed by T. F. Colemen and A. R. Conn is improved in this paper, and the improved algorithm can solve nonlinear programming problem with quality constraints. It is shown that the improved algorithm possesses global convergence, and under some conditions, it possesses locally supperlinear convergence.