Remanufacturing engineering is the industrialization of high technology maintenance of the waste productions, and it is important technology support of circular economy and energy saving & environmental protection industry. The remanufacturing engineering in China has experienced three periods, namely industrial emergence, scientific demonstration and governmental promotion. Based on performance improvement method and size restitution method, Chinese characteristic remanufacturing engineering takes advanced life assessment technology, nano surface engineering and automated surface engineering technologies as the key remanufacturing technologies, and the main character of which is that the performance and quality of remanufacturing products are at least as good as the new ones of the prototype, with cost at 50 %, energy saving 60 %, material saving 70 %, which will improve environmental protection obviously. The new remanufacturing mode with Chinese character has gradually established and obtained great achievements.
The power converter, which is one of the critical equipments of the system, must meet the requirements of high power density, high reliability and excellent control performance. Great development has been achieved in China about wind power converters, which is still lagging behind the advanced level of the world. In this paper, some critical technologies of direct driven wind power converter systems are introduced and the related design ideas are proposed.
The present work devotes to the calculation of relativistic and non-relativistic electronic state and energy for atoms C, O, S, Se, Te, Sm and Pu. In comparison between the relativistic and non-relativistic electronic energy,it is concluded that if energy difference of relativistic and non-relativistic electronic energy for O atom is supposed as unit, then there will be 17.5,479,6 781 and 46 166 for S,Se,Sm and Pu ,respectively. The energy difference of relativistic and non-relativistic electronic energy for Pu is about 8.72 % of its total energy. Therefore, it is quite necessary to calculate heavy atoms using relativistic theory.
This paper briefly introduced the barrier risk eliminating and emergency dredging of Bailong River in Zhouqu County, including the scheme compilation and perfecting, and the key aspects and actual considering etc. Based on the target decision-making, systemization and dynamics, the important meaning and effect of the disaster reduction project management in handling natural disasters and risk eliminating succor were analyzed, and the methods for improving the capacity of scientific disaster reduction were also discussed.
This paper summarized the status of comprehensive strengthening mechanism of steel. By using chemical phase analysis, X-ray small-angle scattering, RTO and high-resolution TEM observation, the properties of nano-scale cementite precipitates in Ti micro-alloyed high strength weathering steels produced by thin slab continuous casting and rolling process were analyzed. Except nano-scale TiC, cementites precipitates less than 36 nm and high volume fraction were also found in Ti micro-alloyed high strength weathering steels.The volume fraction of cementite less than 36 nm is 4.4 times as much as that of TiC in the same size. Cementite with high volume fraction has stronger precipitation strengthening effect than that of nano-scale TiC, which can not be ignored.The precipitation strengthening contributions of nano-scale precipitates of different types and sizes should be calculated respectively according to the mechanisms of dislocation intersection and dislocation bypass, and then be added up with the contributions of solid solution strengthening and grain refinement strengthening.A formula for calculate the yield strength of low carbon steel is proposed, and the calculated yield strength considering the precipitation strengthening contributions of nano-scale precipitates and the comprehensive strengthening mechanism of steels matches the experimental results well. The calculated σs=630~676 MPa, while the examined σs=630~680 MPa. The reason for grain refinement strengthening can not directly plus dislocation strengthening and the performance form of phase transformation's influence on steel strength were debated.The applications for comprehensive strengthening theory were summarized, and several scientific questions for further study were put forward.
This paper analyzes the dynamic nature of real-time traffic network performance measurement, with particular focus on random traffic flow fluctuation, traffic deferred conduction effect and traffic periodicity. The limitations of the traditional traffic network evaluation methods based on traffic V/C is discussed; followed by the presentation of a novel approach for real-time traffic network performance evaluation, which solves the previous technical issues such as data collection and processing with no blind region, dynamic spatial-temporal traffic network performance analysis and evaluation threshold calibration. The proposed approach is validated in a case study using the Beijing traffic network, which proves its rationality, efficiency and practicality. The implications of the research and methodologies presented in this paper provide new theories and perspectives for infrastructural planning, dynamic road network performance evaluation, etc.
The airflow characteristics impacted on the drought areas were analyzed with V-3θ plot which revealed characteristics of the atmospheric thermal structure. The relationship between the atmospheric thermal structure and the variation of earth rotation (length of day, nutation, polar motion) was analyzed with the update data of IERS. Based on the total momentum conservation of earth and atmosphere, the variations between the atmospheric thermal structure and the earth rotation were restricted to each other. The research results showed that large scale drought was related to the air path change caused by characteristics of atmospheric structure and the earth rotation.
Based on probabilistic fracture mechanics, the simulated durability test is performed to study the details with angle of side-frame of wagon bogie made of B grade steel. A new general computational method is proposed to evaluate the EIFS(equivalent initial flaw size) distribution, and the probabilistic crack exceedance model is established. The structural damage value is evaluated from the viewpoints of the survival probability P, stress level σ, crack initiation time t and economic maintenance limit ae, and the corresponding economic life is predicted according to the actual measured stress spectrum. As a result, the TTCI(time to crack initiation) can be better characterized by the three-parameter Weibull distribution, and the validity of general EIFS distribution parameters obtained by the new computational method are verified by the K-S checkout. Furthermore, the structural damage value is quantitatively evaluated by the probabilistic crack exceedance model.The predicted economic life tends to increase with the increasing of the crack exceedance probability, and the rationality and validity of the new computational method and probabilistic model are proved.
Train traction simulation of high speed motor train set has significant role with the rapid development of our country's high speed railway. The calculation method of train traction simulation of high speed motor train set is studied and its differences with general train traction calculation and its relative key theories are provided. The structure and functions of our independently developed traction simulation system are introduced afterwards. The actual applications of Beijing—Shanghai high speed railway include: calculation of four different train running projects; calculation and analysis of position and effect for a contact wire neutral section; simulation of utmost speed test in leading part of Beijing—Shanghai high speed railway. It is concluded by applications that the method of train traction simulation of high speed motor train set has good simulation precision and practical usage. It provided an efficient way to our country's high speed project constructions. The development direction based on it are proposed in the end.
Based on the feature that offshore wind turbine tower supporting structures are affected by soil foundation and the ocean flow, the paper establishes 3D finite element numerical model to get dynamic characteristics of supporting system structure of different scour depths and discusses its change law in order to provide scientific basis for dynamic stability design of offshore wind turbine tower supporting structure.
According to the feature of sandstone weathered and absorbed water heavily, the authors analyzed the physical and mechanical properties and chemical composition of the sandstone experimentally, then studied influence of blasting disturbance, water content, sample bedding on stress-strain strength characteristics through uniaxial and triaxial compression tests, and found that the sandstone would become weak in the strength when it absorbed water, and its cohesion decreased and showed significant anisotropy while friction angle was not changed. After the sandstone underwent blasting, its uniaxial compressive resistance and elastic modulus decreased, and Poisson ratio increased. As the sandstone has obvious bedding properties, the strengths of sample obtained from two different loading irections are different obviously. Based on the stress-strain curves from the triaxial tests, the authors found the stress-strain curves could be described well by the modified Duncan-Zhang model.
Based on the coupling relation between the ancient monsoon change and the biologic produce gross, combining with the develop process of region geologic evolvement and the disabuse products of earth satellite remote sensing images, the startup blaze factor and mutual coupling mechanism and its drive transfer effect that caused the ancient climatic environment change in the plateau internal area were researched, This direction now still belong to frontier field in the evolvement of plateau geologic environment and its global change.
According to the CBM(coal bed methane) features and possible difficulties in fracturing techniques, a new hydraulic fracturing method with casing injection, high output and activated water carrying sand was developed. It showed great effect in the Qinshui coal field.
The flotation performances of four tertiary amines (DRN, DEN, DPN and DBN) on kaolinite were studied in this paper. All the four tertiary amines show very good flotation effects on kaolinite, and DEN does the best, with the highest flotation recovery of 92 %. In the acid pH scale, four tertiary can float kaolinite well because their cationics absorb onto the surface of kaolinite by electrostatic force; with the increasing of pH, the content of cationics was decreased to result in the lower flotation recovery. On the basis of Zeta potential, the surface of kaolinite is mainly electro-negative in the whole pH region, and its Zeta potential is remarkable increased after kaolinite was affected by four tertiary amines. Both the results of FT-IR spectra and Zeta potential show that four tertiary amines are absorbed onto the surface of kaolinite by electrostatic force. The flotation differences of four tertiary amines are due to the electronic effects and space steric effects of the substituents belonging to N atom in the amine molecule.
On the basis of the condition and characteristics of water resources in Northwest China, the paper analyzes the existing problems in water resource development and utilization. Meanwhile, some fundamental principles of scientific utilization and management of water resources in Northwest China are also discussed in this paper. Ultimately, the author ends this thesis by proposing some legislative proposals on scientific utilization and management of water resources in Northwest China.
Water diversion and regulation is an emergency measure to improve the water quality of local Taihu Lake. The effectiveness of the measure is proved through experiences and studies for years. Because of the complexity of water diversion works and some impacts of uncertainties, the diversion project may bring some impacts on water environment along the diversion channel while it improving some local water environment. Especially in the rivers west of Wangyu River, some flows are blocked off. So the risks of the retention and transfer of pollutions in the Wu Xi Cheng Yu Rivers will rise up. According to the four drainage programs, by analysis of the hydrodynamics change and impact comparison of diversion project on water quality change in the west of Wangyu River, the retention time, intensity and transfer scope, and the risk of the polluted water were assessed and the corresponding emergency measures were proposed.
The information construction colleges and universities in China in infrastructure construction has obtained rapid development,and it also has exposed a large number of application and management problems. Only through the IT governance , we can organically combine the information technology in colleges and universities with college's mission and strategic goals to ensure that information construction projects can be seen and controllable, and the risks of information technology and processes can be balanced ,and then the information technology resources can be integrated into a kind of its advantage resource eventually.
This Issue
Jan 2011, Volume 13 Issue 1