By analyzing the progress of materials processing, the application and the importance of solidification technologies in the field are stressed. It is pointed out that the solidification technologies offer some new method´s for the preparation of advanced materials as well as powerful ways for improving the traditional materials processing, which is now on the way of optimizing the facts of shape forming, microstructure improving, consume reducing and environment protection. Some emerging research topics about solidification processing and the possible technological progresses are also predicated.
This paper puts forward a kind of method about type synthesis of the one-dof planar closed chain's mechanisms, that is , “type synthesis by planar graph”.
The program of the method is that components of the chain are set up by the mechanical function first of all, then the planar graph is configured by the chain, finally the type synthesis and inversion of mechanisms are made by the graph, and the optimum structural kinematic scheme is formed.
There is not any large deposit associated with giant layered igneous complex in China. But superlarge and large magmatic deposits have been discovered in many small intrusions. Therefore, research and exploration direction having great potentialities for the magmatic deposits of small intrusions is defined. The Jinchuan and Panzhihua deposits represent two important types of the magmatic deposits in China.
Based on the experiments of the new type square wave YAG laser's stability, reliability and nonlinear application, the transmission process of flat top laser pules, which is produced with the slowly adjusting Q cavity flowing empty technology in the uneven media is analyzed.
This paper introduces a series of challenges which modern power system in ships are confronted with the realization of All Electrical Ship and the application of sensitive loads and new weapons. The author analyses the potential application in power system in ships based on the development of superconducting magnetic energy storage (SMES) as a new storage device and points out the key topics for application of SMES to electric power system in ships in the future.
After stating the complexity of stability problem and the importance and technical difficulty to make safety monitoring model for layered rocky slope of foundation of the south tower and resistance body of south anchorage in Jiangyin Yangtze Bridge, this paper introduces the technical methods to wake the model of tower load distribution, the monitoring and alarm model of residual anchorage thrust, j. e. , cause factor of slope stability, the comprehensive fuzzy evaluation model for slope safety based on external deformation observation results and the forecast model for the stability of layered rocky slope based on observed internal shear displacement.
PCI bus has become the primary bus standard of PC. It is widely used in numerical-control-system ,such as 3D laser formation, high speed laser marking, laser cut and so on. This article analyzes several technique problems and puts forward solving strategy. A graphic processing card for high speed laser marking machine has been designed, which can raise the efficiency by 25%～30%.
The lubrication effect is directly affected by flowing characteristic of fluid. The viscosity distribution of lubricant is the key point to the bearing. The viscosity variation will directly influence flowing velocity of the lubricants. Apart from temperature rise, the speed change will result in rare faction of the cut in the fluid. In case thin film lubrication, the thickness of fluid film is tiny, relative moving velocity of interparticles is larger in the lubricant, therefore, the variation of lubricant properties will be more prominent. The velocity characteristics of lubricant in micro-clearance are researched with the continuous correcting model of viscosity. The distribution laws of velocity are obtained in the micro-clearance. The data are provided for the study of temperature field and rare faction of the cut under the thin film lubrication.
For determining calendar life of aircraft structure, this paper thought that the damage of the aircraft structure resulted from the synergistic effect of ground parking environment and fatigue load. On the basis of dynamic S-N curve, traditional nominal stress-method and Miner theory, this paper put foreword the method that was applied to the estimation of calendar life of aircraft structure.
In this paper, the historical precipitation data has been analyzed, the temporal spatial distribution of atmospheric precipitation of north and west of China have been studied in detail. Choosing 5 global climate change models recommended by IPCC, the atmospheric precipitation of China in 2030 has been analyzed under different scenario. Finally, the future trend of atmospheric precipitation in north and west of China is revealed and the preliminary judgment of the probability of mitigating the drought in north of China has been given.
The author applies covertly and macroscopically the SPAC theory model to the water saving system of well irrigation rice in Sanjiang Plain. Several sub-systems have been taken as a whole large system, such as groundwater, machine well, sunning water pool, channel, field, environment and so on. Through applying modern building models and optimization technique, the author analyzes the mechanism and theory of each subsystem, some mathematical models about groundwater, sunning water pool, channel, water production function, water requirement and available rainfall have been built. At last, through designing the typical demonstration area, the author combines several water-saving techniques into a whole system. Thus, the goal of raising water temperature 5～15℃ , saving water 17.1% and increasing yield 700 ～1 000 kg/hm2 canbe reached.
The packaging of micro electro mechanical systems (MEMS) is referred to first-level packaging and limited generally to the preservation of wafer in this paper. It is based on bulk silicon bonding technology and film sealed technology. The bulk silicon bonding technology includes electrostatic bonding, silicon direct bonding and interfacial layer assisted bonding. It is used for making material acting as substrate or cover of the chip. The film sealed technology includes whole-wafer operation, local-wafer operation and selective preservation. It is used to seal micro channel or micro hole to form a vacuum or low-pressure cavity or protect from atmosphere influence. The very high importance not to forget packaging at the beginning of a project, when hoping to industrialize MEMS is discussed. In order to obtain high performance-price ratio,it is necessary to weigh the device performance against the chip complexity. The commercialized pressure sensors, accelerometers, digital micro mirror devices, etc., collected from literatures are used as examples.
Parallel kinematic machines are in the process of industrialization. In this paper, research and development of parallel kinematic machines is investigated from various aspects including machine structures, application fields, drive principles and controllers. Some important research projects are introduced. Several key techniques and possible development directions are put forward.
More than 80% of crude produced in China are those crudes with poor flowability, either waxy crudes with high pour points or viscous heavy crudes. How to transport these crudes safely and with less energy consumption has been a topic for research and development to the petroleum pipeline industry in China, and significant technology development has been made in the past over 40 years, typically the pour-point depressant (PPD) technology for waxy crudes. Flow characteristics of these two kinds of crude and the mechanism for their poor flowability are briefly introduced. The up-to-date research and application of technologies for pour point depression and drag reduction in crude pipelining are summarized, including the PPD technology for waxy crudes, and the dilution pipelining, the oil-in-water emulsion technology and the core annular flow technology for heavy crudes. Development tendency for these technologies is discussed. Suggestions are made to further studies. It is expected that the PPD technology will continue to be a dominant technology for pipelining waxy crudes safely and with less energy-consumption.
Presently in China, studies on the PPD technology should be focused on the highly-waxy Daqing crude oil, which accounts for about one third of total crude oil production in China. For heavy crude oil pipelining, it is believed that the oil-in-water emulsion technology will find more application, and exploitation of offshore heavy crude oil fields in the Bohai Sea of China urgently requires that study on this technology be aimed at pipelines concurrently transporting heavy crude oil and produced water. Further updating of existing technologies and emerging of new technologies call for enhanced basic research, innovative ideas and approaches, and multi-disciplinary studies.
The new SEA method developed in this dissertation is the integration of virtues from the mobility analysis, classical SEA and classical theory of power flow, which fits for vibration and noise analysis of complicated coupled systems. This research provides a theoretical base for study on vibration transfer between structures and noise radiation of complicated mechanical systems, and it also offers guidance for isolation and noise control of engineering structures. Contributions of this dissertation are as follows： First, in view of the disunion of SEA parameters in classical SEA, a union definition of SEA parameters is brought forward. Secondly, some elements that influence energy transfer between mechanical structures are separated and corresponding parameters are introduced to investigate those influences separately. (1)Linking style coefficient is introduced to denote the rule of vibration energy transfer when structures are linked at one point, some points or a line. (2) Non-conservative coupling coefficient is introduced to describe the influence of isolation or damping when structures are isolated or damped. (3) Indirect coupling coefficient is introduced to research the property of vibration energy transfer when two structures are indirectly linked by other structure. Thirdly, on the basis of above, gradation analysis is put forward to simplify the vibration analysis of complicated coupled system. Then, by using theoretical achievements above, the property of vibration and noise radiation of underwater vehicle is analyzed by the developed SEA for the first time. Levels of vibration and sound power induced by two different underwater vehicles are predicted. The analysis results agree well with experiment results. Finally, based on the analysis, the direction of noise control of underwater vehicle is pointed out.
In order to help solving the technical puzzles of lacking in scientific, reasonable and quantitative surrounding rock stability criteria in the initial lining during tunneling excavation by NATM and occurring of many cave-ins, in this paper some viewpoints are put forward, the essentials of which are as follows： 1. Advance the basis for the hypothesis of deformation rate ratio criterion (DRRC) and the method for obtaining the threshold of this criterion, and enumerate five typical cases for the application of this criterion to the tunnelingexcavation; 2. The success and failure in the Maoshan expressway tunnel excavation are deducted and verified from positive and negative aspects. DRRC was used in two excavating sections to forecasted dangerous situations resulting in coming safely out of cave-in accidents, while the use of DRRG was compelled to stop in another excavating section and a big cave-in accident happened; 3. Obtain the method of DRRC for constituting a typical information method, which is characterized by the combination of prototype information and typical information. DRRC is a kind of hypothetico-deductive method, and it is also a preliminary application of metasynthesis from the qualitative to the quantitative.