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Three-dimensional analysis of the modified sloping cooling/shearing process
A self-designed setup of modified sloping cooling/shearing process was made to prepare the semisolid Al-3wt%Mg alloy. A three-dimensional simulation model was established for the analysis of preparing the semisolid Al-3wt%Mg alloy. Through simulation and experiment, it is shown that the sloping angle of the plate greatly affects temperature and velocity distributions, and the temperature and velocity of the alloy at the exit of the sloping plate increase with the increase of the sloping angle. The alloy temperature decreases linearly from the pouring mouth to the exit. The alloy temperature at the exit increases obviously with the increase of pouring temperature. To prepare the semisolid Al-3wt%Mg alloy with good quality, the sloping angle θ=45° is reasonable, and the pouring temperature is suggested to be designed above 650-660°C but under 700°C....
2020-11-11 22:33:38浏览：74
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Analysis of prompt supercritical process with heat transfer and temperature feedback
The prompt supercritical process of a nuclear reactor with temperature feedback and initial power as well as heat transfer with a big step reactivity (ρ0>β) is analyzed in this paper.Considering the effect of heat transfer on temperature of the reactor,a new model is set up.For any initial power,the variations of output power and reactivity with time are obtained by numerical method.The effects of the big inserted step reactivity and initial power on the prompt supercritical process are analyzed and discussed.It was found that the effect of heat transfer on the output power and reactivity can be neglected under any initial power,and the output power obtained by the adiabatic model is basically in accordance with that by the model of this paper,and the analytical solution can be adopted.The results provide a theoretical base for safety analysis and operation management of a power reactor....
2020-11-11 22:33:38浏览：60
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Geochemical characteristics and formation process of natural gas in Kela 2 gas field
On the basis of a large amount of natural gas components and the carbon isotope as well as some other analysis data in Kela 2 gas field, the geochemical characteristics, source, origin, and formation process of natural gas have been discussed. The components of gas in the field tend to be "dry", and the drying coefficient is close to 1.0. The carbon isotope tends to be heavier, for instance, the average of 13C1 is 27.36‰ and that of 13C2 is 18.5‰. Comprehensive analysis shows that humic natural gas in the Kuqa petroleum system comes mainly from Triassic and Jurassic source rocks, and the contribution of Jurassic source rocks to the pool maybe is more than that of Triassic rocks. The main cause that the gas tends to be dry and bears heavier isotope composition lies in the fact that Kela 2 natural gas is the accumulation of late production of humic source rocks, and it is affected by the abnormal high pressure as well. Considering the hydrocarbon generating and structural history, we can regard the gas pool formation processes as twice filling and twice adjusting (destroying), that is, the filling and destroying process in the early Himalayan movement and the filling and adjusting in the late Himalayan movement....
2020-11-11 22:33:38浏览：76
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Dynamic Model and Performance of Absorption Heat Pump in Shut-down Process
The dynamic model of LiBr absorption heat pump in shut-down process is established. The simulation results show good agreement with the experiments. The dynamic performance of high-pressure generator, low-pressure generator and heat exchanger are analyzed in detail. The proper shut-down mode of the heat pump is presented,which, in consideration of solution parameters, has a great effect on the possibility of crystallization of some components....
2020-11-11 22:33:38浏览：71
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The Process of Regression from Alienation to Humanity——An Analysis of Great Expectation by Charles D
Great Expectations, a later work of Charles Dickens, centers upon the life experiences of an orphan, Pip. The novel elaborates his desire to be a gentleman on the outset and after a series of experiences the downfall of his great expectations. Pip's physical alienation from the past and the familiar environment results in the psychological departure from innocence and humanity. The influence of environment upon one's fate, Dickens's main philosophical belief, is manifested in the novel....
2020-11-11 22:33:38浏览：61
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An improved and scalable process for 3,8-diazabicyclo [3.2.1]-octane analogues
An improved and scalable process for substituted 3,8-diazabicyclo [3.2.1]octane was developed. N-Benzyl-2,5-dicarbethoxy-pyrrolidine 2 was reduced to N-benzyl-2,5-dihydroxymethylpyrrolidine 9 and subsequently debenzylated to afford N-Boc-2,5-dihydroxymethylpyrrolidine 10. After mesylation of the diol 10 and cyclization with benzylamine, a diversity of scaffold, 3,8-diazabicyclo [3.2.1 ]octane analogue 12 was obtained in a total yield of 42% in five steps....
2020-11-11 22:33:38浏览：71
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Calculation of railway transport capacity in an emergency based on Markov process
A method is proposed to calculate the railway transport capacity in an emergency to support the dispatching work of control centers.The effect of an emergency on section transport capacity is analyzed and the basic method to calculate the transport capacity is presented.The results show that the situation-changing process in emergency is actually a Markov process.The calculation rule is presented based on division of the time segment during which the emergency lasts.The algorithm is designed to calculate the transport capacity of each time segment.The pessimistic strategy and the fuzzy strategy are proposed to determine the computing value of the transport capacity of each time segment,to satisfy the calculating requirements in different occasions.Our study shows that the method is reasonable and practical and the method can be embedded in the train dispatching system to support the operation work in an emergency....
2020-11-11 22:33:38浏览：62
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Combined process of sequencing batch reactor activated sludge process and constructed wetland for do
By combining sequencing batch reactor (SBR) activated sludge process and constructed wetland (CW), this study is to achieve the domestic wastewater treatment. Our purpose was to determine the optimum operating parameters of the combined process. The process involved advantages and shortages of SBR and CW. Under normal temperature, the 3rd cycle (SBR's operation cycle is 8h: inflow for 1h, limited aeration for 3h, sediment for 1h, outflow for 1h, and idling for 2h; CW's hydraulic retention time (HRT) is 24.8h and hydraulic loading is 24.5m3/m2d) was the best cyclic mode. The effluents can meet the standard GB/T18921-2002: "The reuse of urban recycling water: water quality standard for scenic environment use". In the 3rd cycle, the efficiency of CW was the maximum, and energy consumption of SBR was the minimum. Under the condition of low dissolved oxygen, the removing efficiency of chemical oxygen demand (COD) and ammonia was not affected obviously. Simultaneously, nitrification and denitrification phenomena occured and phosphorus was absorbed obviously....
2020-11-11 22:33:38浏览：58
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Research on Production Process Control Method Combined Stochastic Process Algebra and Stochastic Pet
A hierarchical closed-loop production control scheme integrating scheduling, control and performance evaluation is discussed. Firstly, the production process is divided into two main hierarchies: the lower level is the physical operation level and the upper one is the management level. Secondly, the schedule template for the management level and the activity template for the physical operation level are constructed separately, the tasks in the schedule have the ability to make partial decisions, and the performance parameters are introduced into activity template. Thirdly, the two levels use different model representations: stochastic process algebra for the management level whose output is the control commands and stochastic Petri net for the physical operation level which is the execution of the control commands. Then, the integration of the two levels is the control commands mapping into the lower physical operations and the responses feeding back to the upper decision-making that are defined by some transition functions. Under the proposed scheme, the production process control of a flexible assembly is exemplified. It is concluded that the process control model has partial ability to make decision on-line for uncertain and dynamic environments and facilitates reasoning about the behaviors of the process control, and performance evaluation can be done online for real-time scheduling to ensure the global optimization....
2020-11-11 22:33:38浏览：46
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An Investigation of Stimulating the Autoclave Curing Process of Resin Matrix/Fiber Reinforced Compos
A mathematical model is made which describes the curing process of composites constructed from continuous fiber-reinforced, thermosetting resin matrix prepreg materials, and the consolidation of the composite is developed. The model provides the variation of temperature distribution, the cure reaction process in the resin, the resin flow and fibers stress inside the composite, and the void variation and the residual stress distribution. It can be used to illustrate the mechanism of curing process and optimize the cure cycle of composite material in order to ensure the quality of a product....
2020-11-11 22:33:38浏览：53
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Effects of process parameters and die geometry on longitudinal welds quality in aluminum porthole di
By using the rigid-visco-plasticity finite element method,the welding process of aluminum porthole die extrusion to form a tube was simulated based on Deform-3D software.The welding chamber height(H),back dimension of die leg(D),process velocity and initial billet temperature were used in FE simulations so as to determine the conditions in which better longitudinal welding quality can be obtained.According to K criterion,the local welding parameters such as welding pressure,effective stress and welding path length on the welding plane are linked to longitudinal welds quality.Simulation turns out that pressure-to-effective stress ratio(p/σ)and welding path length(L)are the key factors affecting the welding quality.Higher welding chamber best and sharper die leg give better welding quality.When H=10 mm and D=0.4 mm,the longitudinal welds have the best quality.Higher process velocity decreases welds quality.The proper velocity is 10 mm/s for this simulation.In a certain range,higher temperature is beneficial to the longitudinal welds.It is found that both 450 and 465℃ can satisfy the requirements of the longitudinal welds....
2020-11-11 22:33:38浏览：66
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Process Optimization for AZ91 Mg-alloy Low-pressure EPC Process
The influence of a key process variable on the mold filling characteristics of AZ91 Mg-alloy was studied in the low pressure EPC process.The applied flow quantity of insert gas from 1 to 5 m3/h associated with the pressurizing rate in the low pressure EPC casting process was considered for rectangle and L-shape plate casting. The experimental results show that there is an optimal flow quantity of insert gas for good mold filling characteristics in AZ91 Mg-alloy low-pressure EPC process. The optimal flow quantity of insert gas for the specimens is 3 to 4 m3/h. Either less or higher than the optimal flow quantity of insert gas would lead to misrun defects or folds, blisters and porosity defects. The practice of hub casting confirmed that the low-pressure EPC process with an optimal processing variable exemplified as 4 m3/h gas flow quantity was capable of producing complicated magnesium castings without misrun defects....
2020-11-11 22:33:38浏览：67
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Study of the ship design process model for collaborative design
The ship design process model is the basis for developing the ship collaborative design system under network environment.According to the characteristics of the ship design, a method for dividing the ship design process into three layers is pat forward, that is project layer, design task layer and design activity layer, then the formalized definitions of the ship design process model, the decomposing principles of the ship design process and the architecture of the ship collaborative design (SDPM) system are presented. This method simplifies the activity network, makes the optimization and adjustment of the design plan convenient and also makes the design process easier to control and change, at last the architecture of the ship collaborative design system is discussed....
2020-11-11 22:33:38浏览：74
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Development of vacuum die-casting process
The vacuum die-casting process, started 25 years ago in Japan, has been widely applied. This technology contributes very much to improvement of castings quality. The main factor causing the defects of die castings is the trapped air in the mold cavity, while the key technology of vacuum die-casting process is to avoid the trapped air effectively by evacuating the cavity before casting. At the same time, due to the shot speed and the casting pressure reduced in half, the service life of the die is prolonged and the productivity is enhanced, as well. Vacuum die-casting process is of great significance in improving the die castings quality and making up the shortcomings of super-high-speed shot casting....
2020-11-11 22:33:38浏览：36
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Vacuum-sealed casting process under pressure
A new casting method, the vacuum-sealed mold casting under pressure, has been developed, and thin wall iron castings with high precision and smooth surface have been produced successfully with this casting method. The experimental results show that the liquid iron has a very excellent filling ability because a high negative pressure is formed in the mold cavity during filling process. The vacuum-sealed mold under pressure has very high compressive strength greater than 650 kPa, which is 3-4 times as high as that of the molds produced by high-pressure molding process or vacuum-sealed molding process....
2020-11-11 22:33:38浏览：37
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