The Three Gorges Project is the largest hydropower station in the world with 26 sets of 700MW hydropower units. International tendering with export credit was adopted for the fourteen units on the left bank. It was requested in the tendering documents that foreign companies should jointly design and jointly manufacture the equipment with qualified Chinese manufacturers and foreign companies should transfer their technology to Chinese manufacturers. The participation percentage of Chinese manufacturers should not be lower than 25% of the total contract value. And the last two units will be mainly supplied by Chinese manufacturers. Alstom won eight units co-operating with Harbin Electrical Machinery Company Limited while VGS won six units working with Dongfang Electrical Machinery Company. The contracts are proceeding smoothly. Harbin and Dongfang digested assimilated the transferred technology based on their technology tackling activities carried out in the passed two decades for large hydropower units. They conducted certain technology innovations and tried to be self-reliant on developing, designing and manufacturing large hydropower units. The 12 units on the right bank will mainly be manufactured by Chinese manufacturers, which laid a foundation for supplying good quality, advanced and reliable units for large hydropower stations in China.
Urban geo-environment mainly concerns those regards in and around a city, such as the movement of earth crust and earth surface, conditions of hydrology, geology, geography and meteorology. The relevant studies on geo-disaster reduction and the influences resulted from human activities on the geo-environment are included as well. It is stressed in the paper that geo-environmental protection and management, as well as mitigation of the vulnerability of big cities again the geo-disaster are of significance to the sustainable development for Chinese cities.
The present studies at home and abroad of train derailment are summarized. The following main problems in derailment research are analyzed: train derailment can not be prevented by the normal standards mapped out by each country; the main problems are not grasped; three fundamental problems — the sole solution to the vibration equation group of train-track (or train-bridge) time-varying system is not guaranteed; the excitation source of lateral vibration of the system is not clear; the problem of random analysis of this system is not solved — still exist in calculation theory of train derailment. The approach of random energy analysis, the breakthrough in solving the problem of train derailment, is presented. Preventive measures of train derailment and the calculation method of safety coefficient against derailment are introduced. Finally, four actual instances of train derailment are calculated and the results are in conformity with the actual accidents of derailment and with car vibrations tested by derailment experiments.
In order to change the past research mode of warhead materials, which is mainly based on the firing tests, a new research concept for warhead materials is put forward. The integrated system including computer simulation and properties characterization as well as materials design will be set up based on the service properties of warhead materials, and the volume firing tests will be replaced by computer simulation. In response to the new research concept, some scientific problems that must be solved are presented for implementing definite aim, and the stage results of the fundamental research projects for national security are summarized, the effect of the correlated studies on the future development of warhead materials is also evaluated.
Under the condition of information campaign, Military Geographic Information System (MGIS) is attached importance to as battlefield geographic environment platform for doing battle command automatization, digitalized battlefield and modern weapon system. U.S.A. has invested a great deal of manpower, material resources and money to successively develop and use a series of application systems such as terrain analysis system. Nowadays, U.S.A. is setting about developing TPED and geospatial information system. China began to develop MGIS later, but developed quickly. Now the MGIS software has been developed, which is the first tool software with independent copyright in China. The software adopts hierarchic architecture and objected-oriented design method. It has complete functions, compact frame, and high security. In this paper, based on the analysis of MGIS both in domestic and overseas area, the author mainly introduced the characteristics of MGIS software development, and discussed some problems to be solved in farther development.
This paper describes science, technology and engineering in respect of their natures and corelations, and points out the tasks of scientist, engineer and entrepreneur. It also proposes the ways and means for promoting scientific and technological innovation, economic development and rejuvenation of China.
Since the Ming and Qing Dynasties, there have been many factors hindering the development of science and technology in China, of which, the social and political factors have exerted the most direct and significant influence. “Times of prosperity during the reign of Emperors Kangxi and Qianlong” signified “the last radiance of the setting sun” in the course of withering of feudalism in China. It was not caused by the development of science and technology reflecting the advanced productive forces, therefore, “times of danger” and “last years” followed as soon as the “times of prosperity” passed. The history of late Qing Dynasty was a history of aggression of imperialism and, even more, was a history of decline and fall of feudalism in China. After liberation, the cause of science and technology had got unprecedented development. At one time in this period, because of deviation in holding the historical direction of Chinese revolution by the Party, the cause of science and technology experienced unfavorable influence. After the revolution course was rectified, in the face of the spring tide of the world knowledge economics, China is actively improving the environment for scientific and technological innovation, promoting what is beneficial, removing what is harmful and meeting head-on future.
High-speed maglev with 500 km/h operational velocity can be used for practical passenger transport in the first part of 21st century. It has obvious advantages for long distance, high capacity passenger transport between large cities. From the practical development needs and real situation of the passenger transport in China, based on the detailed analysis of the international progress, after quite serious discussion, since 1998 a suggestion for the development strategy of high-speed maglev in China has been formed. The strategy is suggested to have five steps, i.e. ： a. Study on the strategic position of high-speed maglev in China´s passenger transportation system. b. Construction of a short test and operational demonstration line based on the imported technology, c. Feasibility study for long distance operational line and organization of the internal R & D and engineering work. d. Construction of a long distance operational line and commercialization of the equipmens and engineering. e. Gradual realization of the high-speed maglev network in the country. Some quite encouraging progress has been achieved, and reported in present paper. Suggestion and prospect of near future work are also outlined.
As the largest river in Tibet, the Yalu Tsangpo River (hereinafter referred to as the river) is abundant in hydropower resources in the range of 113 GW. The river has a “U”-shaped elbow in the Great Gorge area to form an ideal site for a gigantic hydropower station of 40 GW——the largest in the world to date.With the foregoing background, this paper outlines a preliminary project program in this regard. In the opinion of the present author, the mountain should be tunneled at an appropriate point to form a massive hydraulic head of 2280 m. The entire project will be divided into three phases with 12～15 GW implemented at each stage.The electrical output of the first phase can be supplied to Southeast Asia and that of the subsequent phases to southeastern China (especially Guangdong Province). The cost estimated for the project is less than that of the Three Gorges project due primarily to the fact that there is no need to consider such factors as flood control, shipping rerouting and population resettlement, all of which translate into immediate economic benefits. Meanwhile, the project will set four straight world records, namely, the largest hydropower station, the largest generating unit, the highest waterfall and the largest gorge. As a result, the project is of immense significance to the sustainable development of Tibet and to China as a whole, and is also bound to exert tremendous international influence. Due to the complexities and size associated with the project, a huge number of difficulties and problems must be fully addressed beforehand. It is hoped that all the involved difficulties will be discussed and analyzed in-depth with a view to reaching scientific and practical conclusions for the project.
A novel AC — DC machine is invented on the basis of the proposed new idea of electric power integration, wherein the stator with one set of 3-phase AC winding and another set of 12-phase DC winding, together with a rotor having a d-axis field winding and a q-axis stabilizing winding, is combined with a 12-phase bridge rectifier, an AC exciter with an excitation system, the automatic voltage regulator as well as a cooling system to form an integral whole. Simultaneous AC and DC power supplies with high quality being available, this new generator is especially suitable for self-contained electrical systems, such as those found on aircraft and ships, where good performance and compact size are essential. Mathematical models of the machine are established and calculation and measurement methods of the model parameters are proposed, providing a theoretical basis for solving the key technical problems. Low-frequency oscillations occurring in a synchronous generator-rectifier system are examined, stability criterion of the system is obtained, and technical measures are proposed to ensure system’s stable operation. With the AC voltage regulated, the DC voltage floats within an acceptable range, which can be achieved through rational machine design. Due to complete electrical separation of the AC and DC circuits and usage of the properly designed 12-phase DC winding, the AC voltage distortion caused by DC commutation and the DC voltage pulsation are greatly reduced, which considerably improves the EMC of the system. Expressions for the peak current and impact torque following a short-circuit fault at DC side or at both AC and DC sides are derived once the strong nonlinearity of the system is ingeniously handled. The principle and methods for on-line real time fault diagnosis of the diodes in the 12-phase rectifier are proposed so that the state of each diode can be easily judged according to the input/output-voltage waveforms. Based on the achievements of above research, AC - DC generators with high performance have been developed, laying the foundation for integration of self-contained electrical systems.
This paper presents the study and applications of water jet technology in petroleum engineering. A mathematic model of pressure and water power attenuation, under the condition of submergence and nonfreedom, is setup through experiments. A novel method and its model are established to gain maximum hydraulic power at bottomhole and optimize water parameters. In addition, the basic equation and structure model of two kinds of resonating chamber are set up according to transient flow theory and hydro-acoustics. Under the impact of drilling biaxial stress, a model of predicting the fracture propagation is founded utilizing rock fracture mechanics. On the base of above models and theories, three new kinds of bits, i.e. extended nozzle roller bit, self-resonating water jet bit and combined jet and mechanical rock-cutting bit, are developed. Also, the paper points the prospects of applications of water jet technology in deep-well drilling, low-permeability reservoir production, and enhanced oil production.
A new simple approach to effectively detect QRS — T complexes in ECG curve is described, so as to easily get the P-wave (when AF does not happen) or the f-wave (when AF happens). By means of signal processing techniques such as the power spectrum function, the auto-correlation function and cross-correlation function, two kinds of ECG signals when AF does or does not happen were successively analyzed, showing the evident differences between them.
A new kind of composite guide that is made of steel and glass fiber reinforced plastic has been developed and researched in view of the present situation that the shaft furniture had been corroded seriously. The GFRP, the properties of which have been changed to have antistatic feature, fire resistance and abradability, is used to replace the traditional steel partly. The corrosion resistance and wear-resisting property of the guide and the shear strength between the interface of steel and GFRP were researched. It is indicated by test and analyses that steel and GFRP can work in a coordinatied way. The corrosion resistance of the guide can meet the needs of mining shaft use, and the corrosion resistant life of the guide is the same as the wear-resisting life which are thirty years or above
With the improvement of China's expressway, how to use expressway economically and safely has became an important problem. Setting up more roads simply, and extending the road net scale can not meet the increasing transportation need. Application of Hi-tech, e.g. modern information and communication technique, to reform the current road system and its management system, can significantly increase the traffic capacity and the service quality of road net. Intelligence transportation system (ITS) is a direction to transport development, and also an important measure to solve the transportation conveyance bottleneck. This thesis, based on the detailed data, analyzed present developing condition of China’s expressway first, then analyzed the overseas expressway development experience, and finally expatiated the necessity of ITS used in China´s expressway by taking the Sichuan Province ITS project as an example.
In this paper, the structure and testing principle of vibrating wire pressure cell are presented firstly. Then, combined with the practice in the south anchorage of Jiangyin Yangtze Bridge, the feasibility and difficulty to monitor stress of rigid interface using vibrating wire pressure cell are analyzed. The expression of rating factor is deduced. And on the base of FEM, the method to modify observation data is introduced. Finally, the relationship between modification factor and medium rigidity is deduced. Study results indicate that, while monitoring the stress of rigid interface, the observed values are less than the actual stress values. Even, they are approximately one tenth of the theoretical value. The reason is that the real load condition of the pressure cell is obviously different from the rating load condition. The rigidity of medium affects observation results.
For market uncertainty and technology innovation, venture capital rose from U.S. and Japan etc. China has developed it since 1984, which is a great help to the development of technology though with some problems appearing.