In this paper, high performance of anisotropic de-upset nanoscale Nd-Fe-B magnets is obtained: intrinsic coercivity Hcj=1 157 kA/m, remanence Br=1.465 T and maximum energy product (BH)max=426 kJ/m3. The fabrication procedure dependence, deformation mechanism and magnetic domains of these materials are discussed. It is found that the strain activation energy of the die-upset Nd-Fe-B magnets is about 380 kJ/mol based on the Arrhenius Model. The interaction domains are the typical characteristics of the magnetic structures of the magnets. And these domains play an important role in the coercivity mechanism and the corresponding maximum application temperature for the die-upset Nd-Fe-B magnets.
Liaodong zone includes eastern actic region of Liaozhong sag and Liaodong uplift, which is between Liaozhong sag and Liaodong sag with good condition of source rocks and favorable reservoir-seal assemblages in Dongying formation. Meanwhile, there are many fault blocks and nose-shaped structures. However, twelve wells were drilled during 15 years without any significant business discovery by foreign oil companies and domestic petroleum enterprises before 2002. Based on deep research of geological condition and analysis on dry wells again in Liaodong zone, we recognized that two main reservoir plays existed at Dongying and Shahejie formation. Moreover, the dominative factor for Dongying is migration and the one for Shahejie is reservoir. According to this guidance, such giant oilfield JX1-1 was discovered with 150 million reserves in the end through right research direction and favorable targets evaluation, which shows great importance of scientific research in oil and gas exploration.
The distribution of niobium on the vertical section of casting of GH169 superalloy pneumatic plate wheel was studied by original position statistic distribution analysis technique in the present paper. On the basis of analysis to ten thousands of primary signals at the corresponding original positions of the sample systematically, the quantitative statistic distribution information was obtained. The biggest segregation degrees of niobium in different areas of pneumatic plate wheel vertical section were calculated accurately. Two new models — the total weight ratio of niobium contents within the permissive content range (C0±R) and the confidence extension ratio of median value (K) at 95 % of confidence limit of weight ratio, were also presented. All these above methods have been used to determine the homogeneity and statistic fitting degree of niobium in the vertical section of casting of GH169 superalloy pneumatic plate wheel accurately for quality control.
In this paper, based on the well-seismic precise calibration and geological-geophysical modeling technology, the corresponding relationships among the lighologic facies, logging facies, seismic facies, attribute facies and reservoir of Changxing Formation were established. Furthermore, by means of seismic attribute extraction and inversion, the sedimentary macrio-face spatial distribution was described clearly. Meanwhile, combined with impedance inversion technique of the gamma logging, the spatial distribution of reef-beach reservoir physical properties was predicted. Through comparing with the exploration wells drilled recently, it's found that the prediction results of reservoir not only are fit for the actual exploration, but also have the high prediction accuracy. Thus, it shows that the method of prediction by geophysical and geology has theoretical directive significance in Yuanba Area and can provide practical reference for the exploration of reef-beach subtle reservoir in other areas.
To review the marine radioactive-pollution monitoring and assessment technology, the sources and components of marine radioactivity were introduced; the development on the methods of marine radioactivity analysis and the technology of monitoring network were appreciated, and the possibility and importance on building the methodologies of non-human species radiation protection and assessment were discussed, including the assessment of marine radioactive-pollution. Some advice for developing marine radio-monitoring technology in China was proposed at last.
According to the poor environment situation of residential building in Tibetan plateau both urban and rural and the shortage of conventional energy sources, this paper presents the basic theories, methods and key technical problems for low energy consumption buildings design appropriate to the local climate natural condition and the social economic background, by the means of large-scale field investigation, detailed testing and calculation on the physical environment and energy consumption and the comprehensive analysis about the basic model of residential buildings. The basic meteorological data for low energy building design are developed. The energy saving building system for city and rural and the new rural ecological residential building model, based on the local culture and social economic development condition, are proposed and designed focusing on the utilization of solar energy. Moreover, exemplary projects are built,which not only meet basic thermal comfort level, but also guarantee the super low energy consumption for heating and cooling. Design standard and atlas reference to low energy building design for Tibetan plateau are compiled, promoting the overall progress of building energy conservation. The results of this study provide an effective reference for the entire Qinghai-Tibet plateau and for other areas of the country.
With the expansion of high-end equipments and products, performance tolerance standard of some equipments and products becomes more and more high. In this case, a large number of high performance parts come into being. The machining of these key parts has changed from pure geometric accuracy requirements to performance-geometry integrated precision machining requirements under the premise of taking performance requirements as a primary target. Such high performance parts often have complex surfaces and ultra-high machining accuracy, and consequently use difficult-to-cut materials with supper-hard, supper-brittle or supper-sticky characteristics. Due to the case that the part performance has complex coupled effect with many factors such as part geometry and material, it is rather difficult to manufacture with a high precision when using traditional machining processes, which often lead to high rejection rate, low machining efficiency and particularly out-of-tolerance part performance. For satisfying the requirement of manufacturing industry, a new digital machining way for high performance key parts is presented in this paper. The characteristics and classified system of high performance key parts are described. Then reasons of high product rejection rate using experiential method and connotations of positive digital machining of complex surfaces are subsequently expounded. Key issues and their research statuses, existing problems and solving measures of positive machining technologies are finally discussed in detail. It provides an effective reference and guidance for the establishment of performance-geometry integrated machining principle, method and process technologies, and then as a result to solve the issue of the precision manufacture of high performance parts.
According to the great demand for the "green" plastics processing technology of the low energy consumption, high efficiency and environmental protection in plastics industry, the plastics processing method and technology based on the elongation rheology, with continuing evolution and innovation of the plastics plasticating and conveying method, are presented and researched on the basis of the plastics dynamic processing method and equipment, and it is focused on that the plastics plasticating and conveying process in the vane extrusion system, the technical characteristics of that and the applications of vane plasticating and conveying technology are discussed. The research results show that compared with the conventional processing equipment, this new technology and equipment shows many outstanding advantages, such as shortening the thermo-mechanical history of the plastics processing more than 50 %, reducing the energy consumption 30 % or so, improving the mixing and blending effects, improving the quality of the products and the adaptability to materials, etc., and it is meanwhile found that the new technology and equipment has special superiority in the fields of the processing for material systems, such as the multiphase and multicomponent composite materials, the shear heat sensitive macromolecular materials, etc.
A kind of pre-encoded code hopping spread spectrum (PCHSS) communication technical system for anti-jamming communication is brought forward and researched after analyzing its necessity based on the deficiency of conventional direct-sequence spread spectrum(DSSS). The main discussions include the basic principle of PCHSS, the differences between PCHSS and self-coded spread spectrum(SCHSS), and some key techniques. The PCHSS basic performance is analyzed finally. The technical system and its basic performance have been proved in practice.
Bad firing precision, huge consumption of projectiles in test and launch unsafety are the three difficult technology problems constraining the development of modern rockets and gun weapons. Firing precision and the launch safety of weapon system depend on dynamics style of weapon system. As a engineering subject of multidisciplinary approach studying the motion styles of weapon system and the force acting on it during launch process, launch dynamics has been a new technological breakthrough in improving firing precision and launch safety of rockets and gun weapon system in the world, provided new theory and technology for design and test of firing precision and launch safety. In this paper, theory and technology of launch dynamics of multibody system and its applications in design and test of firing precision and safety for rockets and gun weapons are studied.
The faults initiated in operation (i.e. incipient fault) with the obscure symptoms and weak features, are always contaminated by a large amount of background noise. Hence, fault diagnosis and prognosis of incipient faults have been the difficulty and focus of the research field. The paper studied the principle of inner product transform of dynamic signals and basis functions, proposed several construction methods of adaptive multiwavelet basis functions,and improved several multiwavelet denoising methods with neighborhood and local threshold. The typical engineering cases of the equipment of heavy oil catalytic cracking, the continuous casting and rolling mills, the air compressor, the electric locomotive and the transmission device of satellite comunication on ship were studied, and the results showed the effectiveness of enhancement of weak dynamic signals and features extraction of compound faults.
With sustained development of economy, large scale highway bridge construction has been undertaken in the past three decades in China. Guided by the policy of "independent construction ,independent in novation", bridge construction technology has developed in a big stride and reached world advanced level. At the same time, the highway construction management system has been transformed from relying on administrative means to market mechanism and modern project management mode has been continuously explored in extra-large project construction. This paper discussed and analyzed project cases and historical experience of the bridge construction from the perspective of technological innovation, project management and sustainable development.
Based on Edong Bridge, which is the second longest hybrid girder cable-stayed bridge with 926 m long main span,the influencing factors and crucial techniques of the main span closure method for long span hybrid girder cable-stayed bridge are studied. After theoretical analysis, numerical evaluation and practical test, the loading assistant closure method is employed in Edong Bridge. The loading assistant closure method, with better thermal adaptability and less influence on bridge line and the forced status,can meet the requirements of the unstressed state control method. Based on the mentioned advantages,the loading assistant closure method is applicable to long span hybrid girder cable-stayed bridges. The conclusion can provide reference for the further design of the similar bridges.
A critical challenge in positron emission tomography (PET) is to develop affordable systems having high spatial resolution. We imagine a PET system, for imaging a region of interest (ROI) with ultra high performances and other regions with normal performances by use of inhomogeneous performances PET detectors. We propose such a prototype, consisting of a few ultra high intrinsic spatial resolution PET detectors and quite a few normal ones. In this paper, we investigate the effect of the location and the number of high resolution detectors. The high resolution detectors are grouped in a continuous partial ring. The initial results show that such a prototype is capable to bring the advantages of significantly improving the spatial resolution in a ROI. For a specified area, the improvement is influenced by the location and fraction of high resolution detectors in a ring. The encouraging results also indicate the possibilities to regulate detectors to achieve high spatial resolution according to the application, which is possibly formulated.