The accelerating development trends of world aeropropulsion technology will be persistent in the 21st century and some revolutionary changes will occurr. With the breakout of some key technologies, the traditional gas turbine engine will be improved greatly. The achievements of power for ultra-supersonic flight vehicles would result in a new generation of aviation with the application of supersonic combustion screamjet and combined engine as turbine based combined cycle (TBCC) engine and rocket based combined cycle (RBCC). With the innovation of new concepts and scheme, some new concept engines will be invented and applied, such as the pulse denotation engine (PDE) and super micro-engine based on micro-mechanical-electron technology. Instead of the conventional hydrocarbon fuel, some new energy will be applied in future advanced aeroengine. The developments of aeropropulsion technology in the new century will promote the progress of civilization and human being society greatly just as in the past 100 years.
Only a few years since its founding, CHERY has not only developed 4 new style cars, part of which are exported, through its efforts, but also been the first car enterprise that establishes car joint venture abroad. That is the road for developing China's auto industry. The government should support such auto enterprises as CHERY, GEELY and HAFEI, which take the road of self-reliance development and proprietary innovation. Preferential policies should be given to them so that they can grow bigger and stronger.
The relationship among the relativity quantum theory and macroscopic physics are investigated based on the viewpoint of historical development of sciences : their contradictory, their common ground and how to get the new fundamental theory through the common development.
There are 8843 state-owned mines of county level and above in China, 2/3 of which has become aged . There are more than 2000 tailing ponds and 1900 coal gangue hills, which reserve 5000 million tons of tailings and 3800 million tons of gangues respectively. They can become new composite mineral materials with the help of the latest technology. Through geological evaluation and experiment study on 4 model mines the authors provide advices as follows： developing mine wastes as building materials and Si-materials; developing gangues as nonmetal materials; geologically evaluating tailings and developing them rationally.
In the beginning of the 21st century, driven by application requirements, the research and development of HEC are getting a new upsurge both in China and abroad. This paper analyses the development status and trends of international HEC, describes the overall development and application status of HEC in China, introduces the major technical features and application achievements of Sunway series high-performance computers; discusses the problems faced by today's HEC technologies, and finally makes some suggestions on how to extend progress in the HEC industry in China.
Through the digestion of the imported technology for the generating sets at TGP's left bank and the participation in the design and manufacturing work by the joint effects of the relevant manufacturing enterprises. China's design and manufacturing of hydropower generating units has reached the world advanced level. It lays foundation for the rejuvenation of china's manufacturing industry and for the international bidding for the first 4 generating sets at TGP's right bank. It also provide useful experiences.
The traditional method of monitoring water transparency is the in-situ measurement by using ship et al. However, this method can not satisfy the large area, quick and real-time monitor demand of the ocean element, because of the inherent shortcoming of the in-situ measurement. It must combine the remote sensing method to fulfill the stereo monitor. This paper puts water transparency as the breakthrough, and studys the water transparency monitoring by using satellite remote sensing. The result shows that the inverse relative error is 22.6% by using remote sensing, and it is even better for clear water. A collection of water transparency products of the China sea for two years is generated by using the inverse algorithm and SeaWiFS data sets. Also, the analysis of the distribution and fluctuation patterns of water transparency in the China sea is carried out by using the established collection.
In this paper, the novel robust maximum entropy clustering algorithm RMEC, as the improved version of the maximum entropy algorithm MEC, is presented to overcome its drawbacks: very sensitive to outliers and uneasy to label them. With the introduction of Vapnik's ε-insensitive loss function and the new weight factors, the new objective function is re-constructed, and consequently, its new update rules are derived according to the Lagrangian optimization theory. Compared with algorithm MEC, the main contributions of algorithm RMEC exist in its much better robustness for outliers and the fact that it can effectively label outliers in the dataset using the obtained weight factors. The experimental results demonstrate its superior performance in enhancing the robustness and labeling outliers in the dataset.
Rigidity of feed system with ball screw in NC lathe has a major influence on loss of momentum and positioning precision. Based on the spring mechanics model and the quality of the feed system, the analytic formulation for the effect of the transition and torsion rigidity of the feed system on the loss of momentum have been given. The analytic formulation for position error have been given, too. Theoretic basis for designing the structure, reducing loss of momentum and increasing positioning precision of feed system has been provided. Moreover, analysis and calculation have been made in combination with an actual example, and significant effect has been obtained.
This paper introduces a type of large scale scanning probe microscope, which adopts the scheme of the separation of large scale scanning from high precise scanning, and the separation of X - Y scanning from vertical detection. The instrument has the advantages such as good repeatability, large scanning scale as well as high resolution. The large scale scanning range is 220 mm × 290 mm × 60 mm and the repeatability is 2～3/μm. The instrument achieves the auto-feeding of the probe, the auto-focusing of the optical microscope and the auto-mosaicking of the scanning image.
At present there is no appropriate method for calculation of stress on external ring of a one-way clutch. In this paper, according to characteristics of the external ring, the method of finite element analyais has been used, the factors which have influence on computational accuracy have been studied, and the stress on external ring of a five roller-type one-way clutch has been calculated. Studies have shown that finite element analyais is really an attractive method for the calculation of stress on parts similar to external ring.
First, based on the law of disease propagation and conservation of population statistics, this paper sets up mathematical models of four kinds of person for SARS, applies mathematical method to analyze the model, and it gets the physiology senses of the mathematical model and mechanism of prevention and control respectively. Second, it sets up predictive models of SARS epidemic disease using BP artificial neural network. According to the data of SARS in Beijing, it predicts and analyzes the model. The experimental results show that the method is simpler, and more effective with high prediction precision。
The air organization research is the basis of thermal environment control in air-conditioned compartment. Reasonable air organization can availably improve the passengers' thermal comfort. By k-ε turbulence model, the air fluid flow and heat transfer in air-conditioned hard-sleeper compartment are simulated numerically. The airflow field and temperature field are investigated in different air supply modes and air supply parameters. The comparison is carried out between the computed and the measured results of temperature and velocity fields. The agreement between them is quite well. A basis is given for the optimized design of air organization in the air-conditioned passenger compartment.
Based on Terzaghi's consolidation theories and Biot's consolidation theories, the consolidating mechanism and consolidating process of highly saturated soil are discussed according to the variety of saturation degree. The influence of saturation degree changing on porous fluid compressibility as well as the whole consolidation process are studied deeply in this paper.
The outstanding properties of concrete placement by towerbelt are the interrupted feeding, high intensity and the capability of direct pouring on the block. However, there would be some problems of back rise of temperature of the pre-cooled concrete during transportation, which is prone to segregation of concrete aggregate if not suitably controlled. Therefore, how to guarantee the concrete placement by towerbelt both at high speed and of good quality is the key issue to be solved during the construction. Some key issues are discussed in the paper at combination with the phase Ⅱ concrete construction of the TGP powerhouse and dam in terms of quality control of raw materials of concrete, counterpart equipment and construction technologies on the pouring block, designs matching and equipment management during the dam concrete placement by towerbelts.
While being an essential business in banking industry and its important role in banks getting more and more prominent with the coming of E-commerce era, the computerization of bank's international trade financing is considerably difficult. The difficulty comes from the complicated operation process, the variety, and dynamic requirement of flexibility of the business, which make it almost a mini-banking system itself. The appropriate and sophisticated software method and technology are needed to build a computer system of this kind. This paper presents a methodology based on semi-finished component model, and addresses a technique to design and implement the system. The technique is featured by building system on a standardized data bus interface, a system framework with menu/icon GUI for general controlling, and clusters of basic object components for elementary business. The basic object components can be grouped, wrapped, assembled into main frame and customized to produce a runnable system for a specific application or adapted to business changing. It also provides a flexible interface for integration with general banking systems and a sound foundation for distributed network banking systems.
During the last decade, water mist fire protection technologies have always been the hotspot in world safty field. Being the large consumer of Halon 1301 and Halon 1211 primarily, navies of most countries in the world felt more enthusiasm about it. US Navy, Royal Navy and other navies have undertaken an extensive study of water mist for fire protection applications aboard ship, especially in machinery spaces. And the results of the testing and theoretic study conducted by them are encouraging. Their study will be summarized in this paper, the purpose of this paper is twofold： to introduce their study to the fire protection workers in China and to provide a reference to China Navy in this field.