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The characteristics of work piece's surface under precision abrasive belt grinding are analyzed.A comprehensive understanding of the reason of low roughness value's surface is found out,which the edge of grain formed compact and crossed micro grinding marks that can compensate for the inconsistence of grinding mark's height in single grinding direction.The grinding test of gear shaft is done for the sake of doing research on the main factors of surface roughness in grinding quenching stainless steel.The results indicate that decreasing the vertical pressure is beneficial to(reduce) surface roughness of work piece,and the surface roughness also can reach the requirement of precision processing when steadily grinding.  相似文献   
323.
In this paper the vital role of the forepart intervening of the estate management for the owner, the estate supervising company and the developers is mainly discussed. The authors believe that the interval for forepart intervening should be between the time of program setting and the time of crest sealing. The authors put forward also a solution for the forepart intervening expenditure. Finally, this paper provides the analysis of question about forepart intervening, and then some proposals and countermeasures are put forward.  相似文献   
324.
It is efficient to extract active components from traditional Chinese medicine (TCM) by using ultrasonic wave. There has been many studies of the strength, frequency and action time of ultrasonic wave influencing extract active components from TCM. There is no report about the research of another parameter-ultrasonic action on-off ratio which influences the process of extrating effective composition from TCM. Using ultrasonic wave to extract resveratrol from the Polygonum cuspidatun sieb, the influence of ultrasonic on-off action ratio on the purity of resveratrol extracts from the Polygonum cuspidatum sieb is compared by analyzing the resveratrol with high performance liquid chromatography. The extracts from herbs under different ultrasonic action conditions have different impurities. The impurity of the extracts is increasing along with decreasing of on_off ratio of ultrasonic.  相似文献   
325.
High DC bus voltage stress is an important issue for the single stage PFC converters in practical application. This paper analyzes the inherent reason of the high bus voltage stress of single-stage power-factor-correction (PFC) AC/DC converters. Four possible resolving schemes are analyzed and discussed, and some of practical implementation circuits topologies are also given. Theoretical analysis and simulation results show that the both series-charging, parallel-discharging capacitors (SCPDC) scheme and bus-voltage-feedback (BVF) method are deemed to be more viable than the other two methods.  相似文献   
326.
Analysis and forecast for market have become important methods of making decision in most enterprises. It is the base of analysis and forecast to effectively store and make full use of the data in the distribution. Technology of data warehouse and OLAP provides the strong function of storing and integrating data, and mathematics methods provides a series of statistics and analysis tools. Combine IT and mathematics methods in the field of analysis and forecast for the data of distribution to put forward a design and implementation plan of application system in supporting decision based on data warehouse. The design exhibits the processes how to build data warehouse and multi-dimensional data, recommends the methods of analyzing and forecasting, and shows a good integration of advanced information technology and decision science.  相似文献   
327.
In this paper the monolithic structural design and joint design of Guangzhou Gymnasium steel roof are introduced. The calculation analyses, including static analysis, dynamic analysis and buckling analysis are introduced as well.  相似文献   
328.
NPV have been widely applied. A majority of the existing calculating methods of cash flow are the static method or the expectation method. It is more reasonable to regard future cash flow as random variable which has certain probability distribution, which shifts with time. But the research about it has been introduced rarely. Through introducing some kinds of existing methods and considering the feature of Markov method, a dynamic method which is used in solved the distributing of indeterminate feature cash flow is showed. So a new kind of dynamic calculation method about NPV is obtained. The method is applied in the calculation to future cash flow of the certain highway investment project of China. The result shows that this method is feasible, effective.  相似文献   
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Method to Predict the Coke Rate Based on BP Neural Network   总被引:2,自引:0,他引:2  
Coke rate is a very important technique index in the processing of metallurgical, and it is also an important goal that should be reached and controlled in practice.The blast furnace is a countercurrent heat and mass exchange reactor involving the solid, liquid and gaseous phases. Using computer encoded mathematical and statistical methods can not get the precise result. An improved 9-9-1 BP(Back propagation) neural network was trained and used in the prediction of the coke rate. The result indicates that the BP nets can predict coke rate accurately and the error between prediction and real coke rate less than 2%. And the use of a hybrid model in actual on-line intelligence control was also discussed.  相似文献   
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