In view of the development of the solidification science and practice, the present paper introduces the basic framework of the current solidified materials system and the basic principles in main developing stages of solidification science. On the basis of modern science and in connection with the modification and improvement of traditional materials, and the developing requirement of new materials, solidification science and technology, as part of the basic component of material science and engineering is carrying out in wide scale research and development in the fields of high-quality castings, directional solidification, crystal growth, rapid solidification, solidification of melt supercooling and other new type and extraordinary solidification processes aiming at precisely controlling structure, shape and properties of products. In this paper some of the above-mentioned work is also described and the developing trend is reviewed.
As the largest in the world by far,the Three Gorges Project (TGP )is a multipurpose development and comprehensive utilization project that can bring a huge benefit by combining floo
The study is aimed at choosing a better predictive model for the accurate description of SARS in Guangdong, Beijing and Mainland China in 2003. Observation and general experience have shown a sigmoid type of curve consisted of four phases comparable to the phases of the SARS growth in 2003 ： an initial lagging period, a period of accelerating change, a period of decelerating change, and a stationary period. In order to model the SARS system, a generalized Logistic growth function has been adopted in the paper. With the officially published data, the main features of evolution of the SARS population size have been obtained using the generalized Logistic growth model by optimizing technique. Then, for getting evolutionary process prediction, several classical S-models such as the Pearl, the Gompertz, Von Bertalanffy, and Richards are tested. The practice of calculations has found that the Gompertz model gives the most accurate results where fitting criteria are estimated as residual sum of squares (RSS).
In this paper, the processes for introduction, research and development of turbot Scophthalmus maximus (L) are reviewed, and social background, academic significance, economic and social benefits and comprehensive effects of turbot introduction engineering. At the same time the potential influence and developing prospect of introduction Engineering are forecasted.
This article presents high differential feedback control idea that does not rely on the model of the controlled system. Its control objective is that the output of the system and its differential and high differentials approximate the given reference input and its differential and high order differentials. It will improve largely the requirement of the control quality. Based on the idea, the high order differentiator (HOD) that is well able to extract differential and high order differentials of measured signals is designed. The proposed HOD has a few parameters and is easily adjusted. Its stability, convergence and filtering characteristic are proved. Furthermore, is designed, high order differential feedback adaptive controllers (HODFC) for unknown model nonlinear SISO and MIMO systems with unknown disturbance are presents respectively, the analysis of stability and robustness of the closed system is given, and linearized decoupling control is achieved.
The fractal-dimension theory and the Shannom entropy theory of nonlinear science are briefly described, and the methods to apply them to analyze AF's information are developed. The grid-dimension values and the Shannom entropy values of P-wave and those of f-wave are computed. The comparison of the remarkable difference between values of these two kinds of waves is given so as to easily determine whether AF happens or not.
This paper analyzes the reason that grey model GM (1,1) often makes errors in simulated data. By contrasting the optimum one to the GM (1,1) about the simulation, it can be concluded that the structure method of background value in grey model GM (1,1) has an important influence on the prediction and adaptability of the model. The optimum background value makes grey model GM (1,1) have better fitting and forecasting precision.
Through using Lagrange interpolation to analyze the limited data of smoke components and concentration attained from the small-scale experiments, it shows the distribution of smoke concentration at same time from different positions and the distribution of smoke concentration field according to time. Considering the random factors existing in these combustion experiments, concentration relative value is provided to contrast data among different experiments. The result shows that distribution of smoke concentration along hallway is mainly affected by mass of fuel and height of the door.
In large scale building fire, it is improper to predict smoke descending using traditional simple two-layer zone model, which divides the total space of the building into upper hot smoke layer and lower cool air layer. In this paper, an improved method, named Cell-Zone Method, is used to solve this problem, which first divides the total space into some small subspaces and then uses traditional two-layer zone model in each subspace. Comparison is carried out between these two methods in fire smoke development simulation in typical large space buildings by CFAST4.02 software package. Results show that Cell-Zone Method demonstrates more applicability than traditional simple two-layer zone model in large scale building, especially in buildings having large scale in one direction.
Based on experimentation, the relationship between the vibration and the noise of rolling bearings is studied. A type of rolling bearing, 6203 - 2RZ, is used in experimentation. The vibration includes the virtual values of the acceleration and the velocity, and the noise refers to the sound-pressure-level. The experiment data are comprehensively processed in the light of the theory of mathematical statistics. According to the results of data processing，the relationship between the vibration and the noise of rolling bearings is not definite. Therefore, the vibration can not represent the noise. The problem of the noise of rolling bearings should be studied independently, the standard of the noise and the corresponding technological specification of the rolling bearings should be established.
Bioremediation is now a promising way to treat oil-polluted soil. In this paper, the author arranged the 7 main factors influencing the bioremediation found in former experiments on 16 samples with the help of orthogonal table and performed a series of experiments. The relative weights and optimal levels of these factors are found; the fates of different components in oil during the late phase of the bioremediation are studied; the structure differences among the residues are analyzed. The 7 factors influencing the bioremediation of oil-polluted soil are： pollution intensity, nutrients (NH4NO3, K2HPO4), oxidant (3%H2O2 Solution), surfactant (TW80), temperature, water ratio and soil disturbance. The weights and optimal levels of factors can change during different phases of the bioremediation. In the late phase of the bioremediation, the main residues of oil pollutant are n-alkanes and isomeric alkanes. The spectrogram of n-alkanes changs from a symmetrical bell shape to an unsymmetrical bell shape. The proportion of isomeric alkanes increases and the base line from C15 to C21 is driven up.
The paper comprehensively analyzes and summarizes main problems that exist in seismic stress calculation of offshore pipelines. In combination with demands of engineering design, some thoughts and advice are given to deal with the problems, which are expected to benefit researches on anti-seismic design method, in addition to establishment of anti-seismic criterion of offshore pipelines.
Out of all the small and medium-sized enterprises those that engage in high and new-technology are the vital new force for technological innovation and technical progress. Technological innovation is the lifeblood of the small and medium-sized enterprises. Drawing experiences of technological innovation from overseas small and medium-sized enterprises for exploring ways that conform to China's actual conditions may, after all, be a judicious choice.
This paper consists of two parts. The first part defines the conception of the industrial technology innovation, summarizes 7 features of it, and then gives a more scientific and comprehensive definition of it. The second part discusses the three major measures of industrial technology innovation ： First, the innovation of new product, which generalizes the classification, characters, definition and component elements of new product, as well as the ten steps of and the principles on innovation of product. Secondly, adoption of new technology, which involves establishment of research institute, attraction of scientific talents and comprehensive utilization of new technology, creation of international technical standard, update of machinery and arts and development of environmental technology. Thirdly, promotion of other innovations, which includes development of new markets, new suppliers and new managements.