Space is the fourth activity field after land, ocean and aerosphere. It is characterized by vacuum, microgravity, stronger radiation and so on. There are many potential values for researching and exploring. Since the dawn of the manned space program more than 30 years ago, it has played an important role in taking human to space, and exploiting space wealth.
The manned space program is introduced on the concept, content and signification in this article, and especially three manned spacecraft—spaceship, space shuttle and space station is described. The author emphasizes that developing manned space program and utilizing space will make a great contribution in promoting the progress of mankind. In addition, the author also imagines Chinese manned space program.
The market demands to continuously reduce the feature size and increase the integrated circuits density towards the new century. For the economical and technical considerations, the major wafer sizes are shifting to 150mm and 200mm, and the mass production of 300mm diameter wafers is expected to begin in 2001 or 2002. Consequently, on one hand, the growth and manufacturing of large diameter crystals and wafers bring about a number of technological problems and on the other hand, impurities behavior, defects and surface mor-point defects and the extended defects, and their relations with crystal growth technology. New finding of metallic impurities such as copper and iron has been particularly described. The behavior of oxygen, carbon, hydrogen and nitrogen that impact material performance in multiple ways havs been also discussed. Interaction between points defects and oxygen precipitates has been treated to be of prime importance. Microroughness, hydrophilic surface state and surface chemical bonds have been investigated in current paper by novel and improved characterization techniques. Since silicon based materials as the alternative material systems have received strong growing interest, the manufacturing technologies and applications of SiGe, silicon-on-insulator (SOI) have been introduced and emphasized. Finally, the author outlooks the future scientific and engineering challenges and opportunities for silicon and silicon based materials envisioned for the sub quarter-micro and nanometer integrated circuits as we approach 21st century.
A new high-tech development with potential wide applications——electrorheological technology (ERT) is introduced in this paper, in which following contents are included. The Definitions of ER effect and ERT, background and history of research and development of ERT worldwide, understanding and mechanism of ERT, potential engineering applications of ERT, principal problems and obstacles in the development of ERT are presented. In addition, some suggestions for ERT development in China are proposed.
The novel information sharing architecture, Information Sunshine, is presented in the paper. It is collisionless, and based on data broadcasting networks other than bi-directional TCP/IPs. Two core concepts of the Information Sunshine idea are Data Stream Environment (DSE) and Personal Demanding Code (PDC). The DSE means that several hundreds gigabytes stream to each household everyday utilizing the great data push .capacity of DVB, and then the nationwide flow of the high speed data stream forms a digital environment. The data flux is so great that thousands of papers, periodicals, Web Server and courseware could be rolling broadcast for several dozens times per day. The PDC code helps each user distinguish favorite contents from broadcasting data stream and intercept them into local hard disk. After storing, users can locally interact with the information without remote connection requirement. Only single-way broadcasting network required by the Information Sunshine architecture, so it is low cost and will drastically eliminate inherent bandwidth collision of bi-directional IP architecture.
A rapid development of crop bioengineering has been made in the world over the last decade, and many transgenic insect-, disease-or herbicide-resistant cultivars have been obtained. The crop bioengineering will play an important role in solving such problems as food security, environment deterioration and resource deficiency. In this article, the progress and the current status of crop bioengineering are reviewed, the problems and challenges we are facing are pointed out, and the trends in the field of crop bioengeering are prospected.
Alkali-aggregate reaction (AAR) may be divided into two kinds： alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR). The chemical reaction between the reactive aggregate and alkali causes serious expansion and results in the deterioration of concrete structure, which is the common character of both. In this paper, the characteristics and differences between ASR and ACR were discussed in detail from expansive process, mechanism and the structural characteristics of rocks. For ASR, the prime essential is the crystallinity of silica, which causes the rocks to display alkali reactivity. Thus only cryptocrystalline, microcrystalline, glassy and strained silica, cristobalite, tridymite, etc. display high alkali reactivity. The criteria and methodology to determine the crystallinity of silica were described in more detail. Through systematically study, it was proved that for ACR, although the crystallinity of dolomite and the Ca/Mg ratio of dolomite may influence the rate of reaction, the decisive roles are the size of dolomite crystals and the distributions in the matrix and the compact degree of surrounding matrix. These results will help to deeply understand the essential of mechanism of AAR. In addition, the geological conditions of formation of reactive carbonate rock were studied, which will be very beneficial to confirm the distribution of reactive carbonate rocks in a region or in a country. Finally the method for distinguishing ASR and ACR was introduced.
Pulmonary artery pressure is an important parameter for clinical diagnosis and physiological research. It used to be measured by the traditional invasive method, cardiac catheterization. A non-invasive method based on audio pulsed-wave Doppler signal and ECG is presented and the noninvasive evaluation system is developed. The key techniques, animal experiment and clinical probation are described in this paper. The key techniques include： wavelet de-noising, new percentile method as well as locating characteristic point with wavelet. According to the data obtained from animal experiments of 9 dogs and 60 cases, the relativity with cardiac catheterization exceeds 80% .
As against the defects of the conventional calculating method for the straightening forces of the roller type straightening mills and the difficulty of straightening forces monitoring of all rollers directly, this paper, through the straightening forces engineering monitoring of the heavy rail-beam straightening mill 1300 (the first and biggest set in China) and straightening forces waveform analysis of top rollers, analyzed straightening forces and straightening process by way of pressure steps (straightening forces component). The built-up process of the indeterminate straightening forces system and the relations among straightening force of every roller was revealed. The division unit measurement theory of straightening forces system and straightening force componentit was discribed and the altogether convenient engineering monitor measurement method was introduced. The general straightening force equation and its engineering computation was given. The straightening force nomogram of H-beam 56 and rail 50 was provided.The above-mentioned theory and methods of straightening forces may be used for heavy roller type straightening mills.
The experimental results were reported on diode-pumped solid state laser with 1 kHz high pulsed repetition rate: 43 mj of single output pulse energy, lower order mode, 43% of light-light conversion efficiency. For diode end pumping, it is quite easy to obtain high efficiency and high output beam quality, the cooling configuration of laser media is simple, too. With fine design, the thermal effect induced by moderate power could be within control.
Based on rate equation analysis, the influences of various characters on output performance were discussed and the optimum experimental parameters were studied, such as the focal size of pump light. In general, the smaller focal size, the lower pumping power threshold. But the output laser power was not maximum. The optimum focal size should be determined according to the actual output laser power.
The young workers (in three days) of five races of Apis mellifera ligustica- ZAU — 1 Italian honey bee (Ea), Chinese Italian honey bee (Eb), American Italian honey bee (Em), Italian Italian honey bee (Ee) and Australian Italian honey bee (Eo) have been used to study the genotype, genotype frequency, allele frequency, heterozygous and homzygous degrees of the malate dehydrogenase Ⅱ (MDH Ⅱ ) isozymes with polyacrylamide gel isoelectrofocusing (IEF-PAGE). There are six genotypes (a/a, a/b, a/c, b/b, b/c, c/ c) in MDH Ⅱ that is coded by three alleles： a，b and c. All of them are found in Ea, Eb and Ee; four (a/b, a/c, b/c, c/c) are found in Eo; three (a/c, b/c, c/c) in Em.The genotype frequencies are aa (0.022), ab (0.028), ac (0.296), bb (0.007), be (0.140), cc (0.508) in Ea; aa (0.003), ab (0.011), ac(0.117), bb (0.006), be (0.156), cc (0.706) in Eb; aa (0.033), ab (0.203), ac (0.224), bb(0.021), be (0.252), cc (0.267) in Ee; aa (0.000), ab (0.000), ac (0.313), bb (0.000), be(0.253), cc (0.433) in Em; aa (0.000), ab (0.006), ac (0.011), bb (0.000), be (0.172), cc (0.811)in Eo. The allele frequencies are a (0.184), b (0.091), c (0.726) in Ea; a (0.067), b (0.090), c (0.717) in Em; a (0.008), b (0.089), c (0.903) in Eo. The heterozygosities (H) of the MDH Ⅱ locus equal to 0.464 in Ea; 0.284 in Eb; 0.679 in Ee; 0.566 in Em; 0.189 in Eo.
The results of test-independence show that there are significant differences in the distributions of genotype frequency, gene frequency, heterozygous and homozygous degrees among five races of Apis mellifera.
Erlangshan Mountain lies at the contiguous area of Tianquan county, Ya´an Prefecture, Sichuan Province and Luding County, Ganzi Zang Autonomous State. The Erlangshan mountainous area with complicated geology and dangerously steep mountains is characterized by harsh weather such as storm, heavy fog, snow, ice, strong wind and various frequently occuring natural disasters, such as landslide, rock falling and debris flow, and therefore the highway in this area is low in standard and poor in condition, resulting in serious traffic jam and frequent accidents, which threaten the safety of traffic. This paper describes the scheme study of disease countermeasures on the Erlangshan section of Sichuan - Tibet Highway and the project comparison of line alternatives, and presents the reasons of building a tunnel in the area, the tunnel alignment and the problems occurred in the construction. The dialectical relationships between a tunnel and its linking works, between a key project and an ordinary project are profoundly analyzed and the related experinences and lessons are also summarized, which will enlighten both the organizers and the designers on the construction of a project.
In this paper, the relationship between the ultra large scale integrated circuits (ULSI) and high purity water and the demands for water quality are described.Several key new techniques of high purity water fabrication are studied. A method for improving the quality of high purity water is proposed, which can effectively decrease the concentrations of total organic carbon (TOC), bacteria and bacterial endotoxins and dissolved oxygen.The contamination of high purity water caused by various pipe materials is described.Some data and examples of author´s experiments are also included.
The requirements for a computer control system used for a rolling mill, especially for hot strip mill, are the high speed control cycle and high speed communication between controllers. A distributed computer control system based on the newest OEM products has been intergrated, and this system has been installed in several mills.
A brief description of the initiative history of gas turbine aeroengine which quite few people know is given. In the 1940's USA, the former Soviet Union and old China all bought the license of Nene gas turbine aeroengine from Rolls Royce Co. UK. Today, after 50 years, USA and the former Soviet Union have become the greatest aviation industrial nations in the world. The fact has proved that attaching importance to the fundamental pre-research on aeroengine is one of the key points in aeroengine development. Therefore measures on how to attach importance to the pre-research to ensure aeroengine industrial prosperity in China are put forward in this paper.
The microsystems research and development extends into various fields including the micro electronic, micro machine, micro-optics, chemistry, biotechnology and materials, making it a multidisciplinary technology integrating various technologies and knowledges. When considering potential uses in future, microsystems technologies are still at the elementary stage. Research today is mainly centered on fundamental technologies common to various microsystems.
May be the focus of the microsystems research and development as followings： science and technology at the microdomain, new signal sensing, transmission and processing technique, nanometer measurement and operation ,new microsystem materials, microfabrication technique.
Two environment problems that disturbed China have been the sand-storm climate in the spring of northern China and the soil deposition of Yellow River. The key solution depends on the soil-water protection of Huangtu plateau. The plateau keeps poorly forestry and plants. Its climate gets drier. The traditional cultivation system increases the water evaporation and inhibits the full seedling growth, which results in the low and unstable yield.
The no tillage system and mulches with crop stalks can highly preserve the rainfall in summer and autumn of last year, increasing the seedling growth rate yield (17〜40) % . The surface soil can be protected from wind erosion, while in rainy summer, the soil can greatly absorb water and slow down the land surface streams and prevent the soil from being taken into the river.
The water-soil preservation of Huangtu plateau includes the efforts from various department and provinces. It calls for the chairmanship of the council of the state and different department as well as different provinces to spread the no tillage system and solve the problems encountered.