Liquid rocket engine is an important member of the space propulsion family and the only propelling means to bring payloads to the first universe velocity in the next historical period, which has vital effects on advancement of space technologies. Propulsion must enjoy priority in research and development of launch vehicles. In the early part of 21st century, China should successfully develop its heavy lift launch vehicles equivalent to that of other advanced countries in the world. We won´t allow them to set up on the bases of simply increasing number and thrust magnitude of existent engines and must develop new types of engine which are more powerful, more advanced and without contamination. Meanwhile, we should begin preliminary researches on rocket spaceplane and aerospike nozzle adopted by it´s propulsion. Along this way, we can finally catch up with the world´s advanced level.
To realize anything which is manmade in the world is an integration of need and possibility. The birth of highrise and super-highrise building can not disobey the rule. Since remote past, human had the will and need of high things, mounting high and living on high places. But the will and need becoming the reality of high-rise building was only in a special age： (1) From the end of 19th century to the beginning of 20th century, after the industrial revolution, productive forces promoted to a large scale, metropolis enlarged, less land had to hold more people; (2) Steel industry expanded, iron and steel played important roles of building materials; (3) The invention of elevator. These factors emerged simultaneously in the United States. After the birth of highrise building, it went straight ahead to the height of super-highrise, right now, 460 m is a new target to be broken through. The history of the development of highrise and super-highrise building may be devided into four stages： Initial groping, Exploring in depth, Modernism and Maturing Stage. A decade ago, accompanied with the development of economics, there was a booming of highrise and super-highrise building in Asia and West coast of Pacific Ocean. After all, highrise and super-highrise building is a phenomenon of economics. From now on, it should be toward biological. There are broad prospects of engineering works, such as dynamics, mechanics and materials. And there are numerous problems of various aspects to be researched, such as the negative influences of human being* s behaviors in super-highrise buildings. Is there an upper limit of super-highrise building? Where is the limit? ……They are worthy to be explored.
In light of tasks creating before ground based air defense radar in recent regional conflicts, this paper outlines features of modern miscellaneous targets as well as the combat environment and ECCM environment of air defense radars, and analyzes briefly the position and function of ground based mid and low altitude defense systems in modem air defense. The author believes that these air defense systems can play an important role in modem air defense and would be the preferred weapon especially against such targets as the cruise missile, attack helicopter, lowaltitude aircraft (including stealthy ones) and anti-radiation missile. The article concludes the new requirement of ground based mid and low altitude defense radars, mainly including good ECCM performance, good low altitude property, the required capability of small target detecting for weapon systems, capability of rapid search and acquisition. The realizability of these requirements in ground based mid and low altitude defense systems is also discussed in brief in this paper.
It has been only 50 years since gas turbine engines arrived in the early 40´s, however, there have been great changes in gas turbine technology progress. Gas turbine engines has been playing an important role in the development of aviation industries.Turbofan engines are always at the leading edge in technical area. It has become the major power for modern fighter aircraft and transportation aircraft in the trunk airlines. Thrust-weight ratio, one of the most important technical parameters of fighter aircraft engine, has been improved from 2 in the early time to 8, while the fuel consumption has been reduced from 1.0 kg/daN ▪h to 0. 6～0.7 kg/daN▪h.
From late 40´s to the early of 21st century, there have been four generation replacements of fighter aircraft. Fighter aircraft engine with a thrust-weight ratio of 8 was emerged in early 7O´s. It remains the main model on active service for developed countries today, and is still under development.Fighter aircraft engine with a thrust-weight ratio of 10 is in development, and hopefully will be put into service by 2003. Aeronautically developed countries have been applying their aeroengine research and development program since 80´s, in order to provide themselves with military and commercial advantages.The target is to demonstrate engine technologies of a thrust-weight ratio of 15〜20 and a fuel consumption reduction of 30%〜40% . It is forecasted that this type of engine shall be successfully developed by the year of 2020, which double the engine capability. It shows that the development of aeroengine technologies is being accelerated.
Facing the 21st century of knowledge and economy, challenge and opportunity run together, difficulty and hope go in parallel. We must seize the chance, go along with the trend to speed up the aero technology development in China. Views and proposals are given in this paper.
In order to establish Shanghai as an international economic, financial and trade centre it is essential to make Shanghai an international navigation centre. With the rapid development of container transport on a global scale, such an international navigation centre should possess hub port with container terminal capable of accommodating large or even super-sized container vessels entering the port. Port Shanghai, located inside the mouth of the Yangtze River, is the only suitable site to build such container terminal, for it has the superiority of being in the immediate proximity of metropolis Shanghai, with superior facilities for conducting international trade and convenient access to the vast hinterland, including the delta area and the entire Yangtze River basin. At present, the only hindrance is the huge shoal forming at the mouth of the estuary, the natural water depth of the channels over the shoal is only 6m, vessels of over 10000 tonnage have to save the tide in entering the estuary. An improvement scheme has been worked out to increase the depth of entrance channel successively to 8.5m, 10.0m and eventually to 12.5m, so that container ships of the 3rd and 4th generations could enter the port all day round, and those of 5th and 6th generations, as well as cargo vessels of 100 000 tonnage, by saving the tide. The improvement scheme consists of regulation works (training jetties and spur dikes) as shown in the figure, in combination with dredging operations.
The differences of chemical characteristics of Fe, Co, Ni, Cu 3d and other eight precious metal elements in M group and Ⅷ group, together with that of precious metal elements of Ru, Rh, Pd, Ag 4d and Os, Ir, Pt, Au, 5d were analyzed in terms of atomic structure. This paper stated that their chemical stability increased from the left side to the right when transverse comparison was conducted and the chemical stability rank occurred as 3d≤4d＜5d when longitudinal comparison was carried out. From the practice of extraction metallurgy of precious metals from copper-sulphide nickel ores, the paper discussed the behaviour of precious metal elements in thermometallurgical processes such as baking-reduction smelting-oxygen blasting and hydrometallurgical processes such as electrolytic concentration, sulphuric acidification of anode slime, wet chloridification, pressured oxidification and optional reduction.
A formal representation of cloud models for mapping between qualitative and quantitative knowledge is presented in this paper.The algorithms for producing the cloud drops are given to describe fuzziness and randomness contained in linguistic concepts. The uncertainty reasoning mechanism is proposed with such cloud models, while several qualitative rules are activated simultaneously.The cloud theory has been successfully applied to balance one-, two- and three-link inverted pendulum systems driven by single motor showing different balancing patterns and some robustness. This intelligent control technique can be used in control of robots and flying objects in space. Moreover, it may have universal significance in revealing the transformation law between qualitative and quantitative knowledge.
The harnessing of the Yellow River has been paid serious attention to by every aspect of society. To start the construction of Xiaolangdi Project will make the harnessing of the Yellow River get into a new course of development. But, at the same time, it will exert a great influence on ecological environment. Based on long-term investigation and research, by using theories of sustainable development and methods of environmental evaluation, this paper analyzes the effect of Xiaolangdi Project on the environment in the areas such as the reservoir and surrounding area, the immigration area, and the fragile area of the downstream. Moreover, the tendency of the water quality changes in the reservoir area and the downstream is analyzed. It is considered that the spatio-temporal effect on environment is not well distributed. Resettlement is the key environmental issue of the project. The different application phases of the project will exert different influence on wetlands, the irrigation area of downstream, the delta and estuary. After the construction of the project, the increasing discharge of waste water in the section of Xiaolangdi to Huayuankou will be the major cause that worsens water quality. So it is suggested to formulate sustainable development countermeasures. (GIS, RS, GPS) integration technology is used to establish the dynamic monitoring system and the prediction geographic information system.
It is a conventional method to build dynamic models of flexible spacecraft with hybrid coordinates. This kind of modeling has gotten a great success both in theory and practice to spacecraft with rigid main body and large flexible appendages. However, modern spacecraft are becoming much bigger and more and more complicated. Their developing trend in structure is： 1. Rigid main body is attached by flexible module, to which kinds of large flexible appendages are fixed. This kind of spacecraft is a complicated structure system composed of rigid main body and composite flexible structures; 2. The flexible multi-modules main body, taking on a lower stiffness, and several kinds of large flexible appendages attached to it make the whole spacecraft as an all-flexible structure system.
It is impossible to build the dynamic equations of a spacecraft by its flexible modes, when some of its flexible appendages are not fixed to the rigid main body directly. In order to take full advantage of the achievement of spacecraft dynamics of rigid main body with flexible appendages, this paper makes dynamic models of composite flexible structure spacecraft by hybrid coordinates with taking into consideration the composite transition of linking point between flexible bodies. The corresponding computing software DASFA 2.0 has been used in space engineering design and analysis.
The two generations of technicians and engineers in small arms industry in P. R. China have been working scientifically in developing of new type of guns. So after a short period of cooperated work, a new advanced squad gun family has been developed based on the weak conditions in China, which brings the level of guns for infantry to the world level. This is highly rated by the army authorization. This guns family were already used to equip the army assigned to Hong Kong in January, 1997 and shall be used to equip the whole army step by step.
Aim To evaluate the clinical effect and safety of high intensive focused ultrasound (HIFU). Methods 78 cases malignant tumors in abdomen and pelvis were classified into two groups： hollow organic tumors group such as carcinomas of ractum and bladder etc. and solid organic tumors group such as carcinomas of liver and pancreas etc. were treated by FEP-BY01 pyrotherapier. The clinical effect was evaluated by different criterion according to their group and the safety was evaluated from painness, skin burning, intestine bleeding, perforation and other aspects. Results In 32 cases of hollow organic tumors, CR (Complete Remission) is 65. 6%, PR (Partial Remission) is 34. 4% at discharge. In 46 cases of solid organic tumors, marked effect rate is 15. 6%, effect rate is 80. 4%, and non-effect rate is 4. 3% (because of ribber stopping ultrasound). HIFU combined with a lower dosage radiotherapy and chemotherapy can speed up tumor falling off or atrophy. Conclusions The HIFU is a kind of safe and effective method to treat abdominal malignant tumor, worth being popularized.
Deep catalytic cracking (DCC) is a novel technology for producing basic organic raw material, especially propylene, from heavy oil. Research Institute of Petroleum Processing, SINOPEC developed the process and catalyst, and a commercial demonstration was successfully completed in 1990 at Jinan Refinery, China. Up to now, 7 units have been constructed and put into production worldwide. The low carbon olefins produced have been further synthesized to high quality polypropylene, polyethylene, acrylonitrile and other chemicals. Currently, the feedstock has been extended to atmospheric residue and tailor-made catalysts are available. The commercial experience of the first DCC plant outside China, TPI DCC in Thailand, is presented.
The age of optoelectronics is the consequence of rapid evolution and mutual integration of the fields of micro-electronics, laser technology and material science. The appearance of optical fibers and laser diodes in the 1960s, one major contribution of optoelectronic technology to information industry, has led to the advent of optoelectronic communications. In the 1990s, great advances in optoelectronic crystals and breakthroughs in laser diode technology have made all-solid-state lasers a practical realization. As a consequence, this will enable optoelectronics to make its further contribution to more national pillar industries in the first half of the next century, in various aspects like material processing in advanced manufacturing, optical storage in information technology, laser displays in entertainment, laser fusion power station, nuclear fission material processing, upgrading of laser weapons, etc.
Microwave Remote Sensing has developed rapidly during last decades, and become a leading method in remote sensing techniques, since its unique features, capability to penetrate clouds and to some extent rain due to its independence from the sun as a source of illumination and other important properties different from visible and IR frequency bands. Microwave remote sensing became a key means for obtaining information from ocean, atmosphere and land in global scale. The frequency range using for microwave remote sensing is extending to millimeter and submillimeter bands.To meet the wide requirements, China enhanced the microwave remote sensing research during last two decades and has got many achievements.In this paper, the microwave remote sensing activities, its achievement, and the state of the arts are described, some strategic suggestions in future development given. Some concepts of space borne system are discussed, and the research areas to which should give priority to develop in national R&D plan suggested. A new concept of remote sensing —a comprehensive electromagnetic sensing system has been suggested to improve remote sensing capability.
Agro-ecological engineering is the significant content of eco-farm construction and is the important measures and technical means for the implementation of eco-farm construction. In substance, it applies principles of ecology and combines with system engineering methods and modern technical measures to establish the production mode for efficiently utilizing agricultural resources and implementing technical system of sustainable development in agriculture. This paper systematically summarizes the ten current technical types of agricultural eco-engineering in China：the agricultural and forestry three-dimensional structure eco-system type for fully utilizing space and land resources; multi-level and graded utilization of material energy; material circulatory ecosystem type of land and water exchange;bio-species symbiotic eco-system type for mutual promotion; agricultural-fishing-poultry aquatic eco-system type;multi-functional sewage self-purification system;comprehensive development compound eco-system in mountainous region; wetland eco-system type for resources development and utilization in coastal beach and marsh;courtyard eco-system type;and multi-functional joint eco-system type of agricultural, sideline production and industry.
The search for bioactive constituents or leading compounds from natural sources especially from Chinese herbal medicine has proved to be one of the most effective ways for the development of new drugs. This paper describes the progress in creating new drugs based on researches on natural products chemistry for many years and some interesting new trends emerging from recent literature.
The key point of study on the chemical constituents of individual Chinese herbal medicine has to be shifted to composite Chinese medicine especially for quality control in the future. The main theme of modernization for Chinese traditional medicine in the coming century will be the comprehensive study of the chemical constituents of composite Chinese medicine. Study on the bioactive principle of Chinese herbal medicine involves an integration of chemical study and bioassay with high throughput screening. It should be emphasized that the investigation of bioactive compounds for creating new drugs is the major task of the whole field. An intimate combination of basic study and drug development should be accomplished under a well-warrantee policy. Natural product research should be featured by the application of modern spectroscopic techniques, such as HPLC/MS/MS and HPLC/NMR and so on.
The development of high explosives could be reviewed as TNT, RDX, and HMX as three historical stages, and now we are coming in the fourth stage which marked by the appearance of CL-20. However, the increment of energy denicty of the CL-20 is only about 10% greater than that of HMX.
For the needs of the improvement of the weapon systems in the next century, it is necessary to search and develop the superior high energy density materials, and it would be some quite new classes of substance.
Performance of nitrogen cluster, such as octaazacubane N8, was calculated by quantum chemists and demonstrated its remarkable prospects, which is represented as an example of the imaginary SHEDM. And it was emphasized that new allotropic forms of nitrogen Nn would be the most promissing substance as SHEDM. Recently N5+ was found in the MS, and it is already prepared as a salt by Christe.
Nitrogen polymer Nn, in which n is a large number and N atoms are connected by covalent bonds in a three dimentioal net structure just as a polymer, is should be paid the greatest attention and would become the most powerful SHEMD in the next century.