Considering both the axial force on the spanning pipeline and influence of sea waves and currents, a perpendicular nonlinear vibration equation which satisfies given boundary conditions is .set up according to the fac...Considering both the axial force on the spanning pipeline and influence of sea waves and currents, a perpendicular nonlinear vibration equation which satisfies given boundary conditions is .set up according to the factual soil supports for the pipeline. Based on the inherent modes of vibration determined from the equation of motion describing free vibrations, the differential equations for the time domain of the equation solution are deduced and established. By the application of time and frequency domain analysis, the sea wave and current force spectrum is derived from wave spectrum and is used as the input spectrum of the vibration equation to deduce the output spectrum, and further determine the probability distribution of displacement and strain. On this basis, the fatigue invalidation probability of the spanning pipeline is found out according to the theory of reliability. Finally, by means of calculation and analysis of a practical sample, the degree of effect of some important parameters on fatigue invalidation of the spanning pipeline span is determined.展开更多
A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effecti...A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effectively and the contours can be drawn smoothly based on boundaries pre-searching and local correction. An experimental example is given to demonstrate that the contours constructed by this method are of good quality.展开更多
In this paper, we propose a strategy of maintaining cache consistency in wireless mobile environments, which adds a validation server （VS） into the GPRS network, utilizes the location information of mobile terminal ...In this paper, we propose a strategy of maintaining cache consistency in wireless mobile environments, which adds a validation server （VS） into the GPRS network, utilizes the location information of mobile terminal in SGSN located at GPRS backbone, just sends invalidation information to mobile terminal which is online in accordance with the cached data, and reduces the information amount in asynchronous transmission. This strategy enables mobile terminal to access cached data with very little computing amount, little delay and arbitrary disconnection intervals, and excels the synchronous IR and asynchronous slate （AS） in the total performances.展开更多
Niobium suboxide powder was pressed and sintered in vacuum into NbO electrolytic capacitor sintered anode..High voltage and constant current formation experiment was performed on NbO electrolytic capacitor anode,durin...Niobium suboxide powder was pressed and sintered in vacuum into NbO electrolytic capacitor sintered anode..High voltage and constant current formation experiment was performed on NbO electrolytic capacitor anode,during which electrolyte was 0.01 % Ha PO4 solution, temperature was 90 C and current was 50 mA per gram sample. Through the relationship between anode voltage and time and scanning electron microscopy(SEM) images of invalidated anode and normal forming anode, invalidation manner and mechanism of NbO electrolytic capacitor anode were discussed. The results show that, the main invalidation manner of NbO electrolytic capacitor anode is not short circuit but open circuit, which is different to that of traditional Ta electrolytic capacitor anode. The reason of invalidation is that anode oxide film whose thickness increases gradually penetrates the "connection neck" among anode powder particles, which leads to the open circuit invalidation of anode. Compared with Ta electrolytic capacitor,NbO electrolytic capacitor has better security.展开更多
Numerical simulation on Francis turbine runner＇s welding temperature field and welding stress field is carded out on the base of solving the problem of welding heat source＇s movement along any spatial routes and the...Numerical simulation on Francis turbine runner＇s welding temperature field and welding stress field is carded out on the base of solving the problem of welding heat source＇s movement along any spatial routes and the problem of heat elimination between the complicated blade and air. The evolvement law of welding stress and the distribution of the stress field after welding are obtained. The results indicate that the peak value of the welding residual stress appears on the outlet edge of blade near the contact area between blade and band or blade and crown. Associated with the distribution of the runner＇s working stress, the invalidation reason of the Francis turbine runner is explained.展开更多
The paper introduced the 5 CrMnMo steel, including the chemical composition, the heat treatment technology, the forging die working condition, and the invalidation form （such as the cavity arris wear, the cavity subs...The paper introduced the 5 CrMnMo steel, including the chemical composition, the heat treatment technology, the forging die working condition, and the invalidation form （such as the cavity arris wear, the cavity subsidence, the cold and the heat fatigue crackle）. Then gave some precautions for prolonging the mould life by improving the heat treatment technology.展开更多
基金This work was financially supported bythe National Natural Science Foundation of China (Grant No.59979018)
文摘Considering both the axial force on the spanning pipeline and influence of sea waves and currents, a perpendicular nonlinear vibration equation which satisfies given boundary conditions is .set up according to the factual soil supports for the pipeline. Based on the inherent modes of vibration determined from the equation of motion describing free vibrations, the differential equations for the time domain of the equation solution are deduced and established. By the application of time and frequency domain analysis, the sea wave and current force spectrum is derived from wave spectrum and is used as the input spectrum of the vibration equation to deduce the output spectrum, and further determine the probability distribution of displacement and strain. On this basis, the fatigue invalidation probability of the spanning pipeline is found out according to the theory of reliability. Finally, by means of calculation and analysis of a practical sample, the degree of effect of some important parameters on fatigue invalidation of the spanning pipeline span is determined.
文摘A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effectively and the contours can be drawn smoothly based on boundaries pre-searching and local correction. An experimental example is given to demonstrate that the contours constructed by this method are of good quality.
文摘In this paper, we propose a strategy of maintaining cache consistency in wireless mobile environments, which adds a validation server （VS） into the GPRS network, utilizes the location information of mobile terminal in SGSN located at GPRS backbone, just sends invalidation information to mobile terminal which is online in accordance with the cached data, and reduces the information amount in asynchronous transmission. This strategy enables mobile terminal to access cached data with very little computing amount, little delay and arbitrary disconnection intervals, and excels the synchronous IR and asynchronous slate （AS） in the total performances.
文摘Niobium suboxide powder was pressed and sintered in vacuum into NbO electrolytic capacitor sintered anode..High voltage and constant current formation experiment was performed on NbO electrolytic capacitor anode,during which electrolyte was 0.01 % Ha PO4 solution, temperature was 90 C and current was 50 mA per gram sample. Through the relationship between anode voltage and time and scanning electron microscopy(SEM) images of invalidated anode and normal forming anode, invalidation manner and mechanism of NbO electrolytic capacitor anode were discussed. The results show that, the main invalidation manner of NbO electrolytic capacitor anode is not short circuit but open circuit, which is different to that of traditional Ta electrolytic capacitor anode. The reason of invalidation is that anode oxide film whose thickness increases gradually penetrates the "connection neck" among anode powder particles, which leads to the open circuit invalidation of anode. Compared with Ta electrolytic capacitor,NbO electrolytic capacitor has better security.
文摘Numerical simulation on Francis turbine runner＇s welding temperature field and welding stress field is carded out on the base of solving the problem of welding heat source＇s movement along any spatial routes and the problem of heat elimination between the complicated blade and air. The evolvement law of welding stress and the distribution of the stress field after welding are obtained. The results indicate that the peak value of the welding residual stress appears on the outlet edge of blade near the contact area between blade and band or blade and crown. Associated with the distribution of the runner＇s working stress, the invalidation reason of the Francis turbine runner is explained.
文摘The paper introduced the 5 CrMnMo steel, including the chemical composition, the heat treatment technology, the forging die working condition, and the invalidation form （such as the cavity arris wear, the cavity subsidence, the cold and the heat fatigue crackle）. Then gave some precautions for prolonging the mould life by improving the heat treatment technology.
