The Central Solenoid Model Coil is a preparatory stage towards the final fabrication of China Fusion Engineering Test Reactor central solenoid. Its analysis and manufacturing experience will be used for the design and fabrication of China fusion engineering test reactor central solenoid coil. The assembly scheme of low-field coil modules of the central solenoid model coil is vertical stacking, which include the top, middle and bottom modules. And the high-field coil adopts the coaxial surrounding structure, which include the inner and outer Nb 3 Sn modules. After the coil is charged, the high-field and low-field modules must maintain alignment, so it is necessary to apply appropriate preload to the coil by using the preload system. In order for CSMC to operate effectively, four strategies are proposed to ensure that the preload system possesses substantial remnant preload while maintaining a small preload difference between inner and outer tension rods. And the preload variation trend under each strategy is analyzed. The study fruition presented in the paper provides valuable theoretical guidance for optimizing the design of preload system and also helpful for adjusting the preload applying scheme.
To achieve much higher operation parameters of EAST device, some key components are upgraded. Fast control coil as one of the key components is updated by using novel stainless steel mineral insulation conductor and the turns are increased to 4, which means the coil's operation environment becomes more severe and larger loads will be encountered. The coil joint is apt to be destroyed in view of the potential defects during the fabrication. Given the numerous advantages, the induction brazing is being considered for the conductor joint connection. The copper mock up is used to carry out the feasibility analysis. Based on the structural size of copper tube, the brazing parameters are calculated and a 2 turns splitting induction coil is designed. Some influence factors effecting the induction efficiency are analysed. It will provide guidance for choice of power supply and the optimization design of induction coil. In addition, the induction experiment is launched and comprehensive joint performance tests are subsequently performed. The test results indicate the joint overall performance could satisfy the basic engineering design requirement, but also some defects are found and more study should be carried out and to further improve the brazing quality.
Through the consideration and influence of friction and setting up the dynamics model of the gear, the author of the present paper conducts a research into the stress distribution law of the gear tooth root, deduces the calculatio n equation of gear tooth root flexural fatigue strength under the action of fric tion and puts forward the comprehensive gear shape factor, which is one of the i nfluential factors of gear tooth flexural fatigue strength.
Scientific space-time analyses of the 1998—1999 basketball league for the concerning techniques in shooting,passing and receiving and rebounding in confrontations indicate the overall distances between Chinese teams and the 8 top teams at the world championship.These distances are distributed through the three periods of basketball technigues——space-time analyzing,gaining and controlling,which not only reveals the fact that Chinese players lag behind the others in techniques,but also urges us to come up with some new ideas and measures in basketball training and its contents.
A US FedEx cargo plane crashed and burst into flames as it landed at Tokyo Narita airport on March 23, 2009.The weather conditions of the crash are simulated and analyzed in this article.A new generation of WRF (Weather Research Forecasting,designed in the United States) nonhydrostatic model 2.2 is used in simulating this process.The horizontal and vertical distributions of several critical physical elements before and after the crash are analyzed.Particularly,the horizontal distribution of potential temperature is diagnosed and analyzed.The result shows that strong surface wind is formed in the region of potential temperature advection gradients,and that the strong surface wind,the strong downdraft caused by the surface wind in the low level and the low-level windshear are the main meteorological causes of this accident.
Abstract This paper studies the change of intergranular corrosion sensitivity of HR3C steel under the condition of 700°C aging by using the scanning electron microscope, energy disperse spectroscopy (EDS), and double-loop Electrochemical potentiokinetic reactivation (EPR) method. The results show that the main reason for the intergranular corrosion of HR3C steel after aging treatment is the precipitation of M 23 C 6 along the grain boundary. The morphology and size of M 23 C 6 also matters in this regard. At the same time, M 23 C 6 precipitation also causes corrosion of Cr around it. M 23 C 6 precipitates at the fastest speed at the beginning of aging, which leads to the rapid increase of intergranular corrosion sensitivity. As aging continues, M 23 C 6 precipitation becomes gradually stable. After the precipitation of large-sized isolated granules, the intergranular corrosion sensitivity of HR3C steel decreases rapidly and maintains at a low level.
Fruits and vegetables are highly susceptible to spoilage, and effective postharvest packaging technology can significantly extend their shelf life of fruits and vegetables. Many studies have shown that the use of electrospinning to encapsulate natural bioactive compounds, including plant extracts, metals, and metal oxides, in active packaging can effectively extend the shelf life of postharvest fruits and vegetables. Electrospun films have the characteristics of a large specific surface area, high porosity, and non-thermal processing, which can effectively improve the encapsulation efficiency and slow-release performance of bioactive compounds. This paper reviews the research progress in electrospinning technology encapsulating natural bioactive compounds for postharvest packaging of fruits and vegetables, and the effect of functional electrospun submicro-fiber films on the postharvest storage quality of fruits and vegetables. Encapsulation of natural bioactive compounds into electrospun submicro-fibers film can improve the function of film, including antibacterial property, antioxidant property and ethylene absorption property. These effects include (1) control of softening, (2) inhibition of fruit browning and enhancement of antioxidant capacity, (3) ethylene degradation, (4) reduction of corruption, and (5) regulation of sugars and acids. This review provides deep insights into the current limitations and future prospects of electrospinning technology in the field of active fruit packaging.
【Objective】 The study was done to make sure Paridea angulicollis Motschulsky adult in Gyanostemma pentaphllum Thunb feild's spatial distribution pattern and sampling method to provid a scientific basis for the occurrence and diffusion behavior and forecast and management decision-making.【Method】 A field distribution map was drawn by recording the number of adult in field which was investigated 100 point and each point was 1 m2,then five different methods(five point,parallel type,diagonal type,Z-size type,chessboard type) were compared with the whole feild investigation in order to find out the best sampling method.Spatial distribution pattern was analyzed by recording the number of P.angulicollis Motschulsky adult using the best sampling method.【Result】 Among the five sampling methods,the five piont sampling method was the best,then the parallel type and chessboard chessboard type.The parallel sampling method made the lowest error rate 0.45,and the lowest coefficient of variation 1.455 9%.The spatial distribution pattern of P.angulicollis Motschulsky adult was aggregated and was density-dependent.The aggregation was affected by some environmental factors and active process.The sampling mathematic model theory provided reference for the best sampling number in feild investigation.【Conclusion】 We could use five point,parallel,chessboard sampling methods for field investigation,and parallel sampling method was the best.The spatial distribution pattern of P.angulicollis Motschulsky adult in G.pentaphllum Thunb feild was aggregated and was density-dependent.
Due to the hazards of fire and the difficulty of personnel escape, fire and personnel evacuation simulation is currently widely used to study the safe evacuation of people in subway stations. With the increasing depth of subway construction, sports fatigue of personnel on long-distance stairs has become a key factor that cannot be ignored. However, current studies cannot consider the impact of fire and personnel fatigue on personnel evacuation simultaneously, and the fire safety evacuation time defined by the currently safety evacuation codes does not consider the personnel fatigue factor especially in deeply subway stations, which need to be further optimized. This paper studied the simulation of evacuation in shallow and deep subway station considering the comprehensive impact of fire and personnel fatigue effects during the entire process from the platform of a metro station to the outdoor ground through upward fatigue experiments and fire and personnel evacuation simulations. An approximate of ascending evacuation test was conducted in an office building, and the attenuation rule of upward evacuation speed with respect to upward evacuation height was obtained. The evacuation speed formula considering the combined effects of fire and fatigue was further derived. In addition, Pyrosim software was used to simulate fires at different locations of subway stations, generate the change data of fire products with time, and insert them into the Pathfinder software through the proposed formula. Finally, the results of evacuation without fire, affected by fatigue, affected by both fire products and fatigue, were simulated and compared in Pathfinder, and the effects of fire source location and escalator operation on evacuation were discussed. It was found that the total evacuation time considering the effects of fire and personnel fatigue in shallow and deep buried subway stations is 63.7 s and 34.0 s longer than that considering only the effects of fire, and exceeds the standard limits by 22.4% and 62.6%, respectively. The recommended evacuation values from the platform to the exit of the station hall in shallow and deep subway stations is 10 min, and the recommended evacuation values to the outdoor ground is 13 min and 17 min, respectively. The most unfavorable fire source is located at the entrance of the platform escalator, and reversing the downward escalator can significantly reduce the evacuation time from the platform to the station hall. The research results provide suggestions for specifications, and also have certain significance in proposing emergency response and evacuation optimization strategies.
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