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1.
According to the features of the turning simulation,a simplified Whitted lighting model is proposed based on the analysis of Phong and other local illumination model.Moreover,in order to obtain the natural lighting effects,local ray tracing algorithm is given to calculate the light intensit of every position during the course of the simulation.This method can calculate the refresh area before calculating the intersection line,simulate the machining environment accurately and reduce the calculating time.Finally ,an example of the virtual cutting scence is shown to demonstrate the effects of the global illumination model.If the CUP is 1.3G and the internal memory is 128M,the refreshing time of virtual turning scene can be reduced by nine times.This study plays an important role in the enrichment of the virtual manufacturing theory and the promotion of the development of the advanced manufacturing technology. 相似文献
2.
Integrating heterogeneous data sources is a precondition to share data for enterprises. Highly-efficient data updating can both save system expenses, and offer real-time data. It is one of the hot issues to modify data rapidly in the pre-processing area of the data warehouse. An extract transform loading design is proposed based on a new data algorithm called Diff-Match, which is developed by utilizing mode matching and data-filtering technology. It can accelerate data renewal, filter the heterogeneous data, and seek out different sets of data. Its efficiency has been proved by its successful application in an enterprise of electric apparatus groups. 相似文献
3.
基于声振理论与实验分析技术，系统研究了金属锯切过程的动态特性，提出快速方便地估算任一夹紧比下弹性圆板结构动态特性的算法。进而探索了减振降噪措施，取得明显降噪效果。 相似文献
4.
A virtual computerized numerical control C CNC） processing system is built for spiral bevel and hypoid gears. The pre-designed process of the solution to locate the way of realization is investigated. A kind of combined programming method and principle of solid modeling are chosen. Multienvironmental programming thought and the inter-connected mechanisms between different environments are applied in the proposed system. The problems of data exchange and compatibility of modules are settled. Environment of the system is founded with object oriented programming thought. AutoCAD is located as the graphic environment. Matlab is used for editing the computation module. Virtual C ＋＋6.0 is the realization environment of the main module. Windows is the platform for realizing the multi-environmental method. Through establishing the virtual system based windows message handling mechanism and the component object model, the application of multienvironmental programming is realized in the manufacture system simulation. The virtual gear product can be achieved in the accomplished software. 相似文献
5.
Storage management strategy can be expressed by a file system. Commercial file system for embedded application is generally
complicated and resource wasted. In this paper, a specified file system adapted to embedded system with flash-based memory
is developed. To guarantee the average usage of flash storage sectors, the strategy of wear leveling and adaptive damage management
is introduced, in which a dynamic storage space management mode and the strategy of first in first out (FIFO) are adopted.
Moreover, the strategy of redundancy design and fast-calculation and tracing is also adopted to extend the life of kernel
sector, which can guarantee the reliable service of system booting. The practical application in an embedded CNC (computerized
numerical control) platform proves that the file system has effective performance. Furthermore, the flash file system can
be transplanted to different embedded platforms by changing a few bottom hardware parameters with universality. 相似文献
6.
The intemational standard ISO 10303.called STEP.has been used to deal with problems in the ex change of product models and the associated data between difierent computer-aided systems.A platform based on STEP for managing product information is presented.This platform includes three components:a product geometry information model,a product feature model and a product visualization model.An information extracting pattern,in which information is extracted from low level elements to high level ones,is adopted in establishing the product geometry information model.Relative elements lists are created based on the extracted product information.With the traversing of these lists,feature extraction methods are proposed,which take advantage of boundary information in product model and avoid the determination of concavity and convexity of curves.Information correlating to features iS stored in a structure named as feature block and the product visualization model iS founded from it.The feature block is used in the platform for information communication and synchronous update among the three components. 相似文献
7.
A unity transformation model (UTM) was presented for flexible NC machining of spiral bevel gears and hypoid gears. The model can support various machining methods for Gleason spiral bevel gears and hypoid gears, including generation machining and formation machining for wheel or pinion on a universal five-axis machining center, and then directly produce NC codes for the selected machining method. Wheel machining and pinion machining under UTM were simulated in Vericut 6.0 and tested on a five-axis machining center TDNC-W2000 with NC unit TDNC-H8. The results from simulation and real-cut verify the feasibility of gear machining under UTM as well as the correctness of NC codes. 相似文献
8.
By analyzing the existing prefix-tree data structure, an improved pattern tree was introduced for processing new transactions. It firstly stored transactions in a lexicographic order tree and then restructured the tree by sorting each path in a frequency-descending order. While updating the improved pattern tree, there was no need to rescan the entire new database or reconstruct a new tree for incremental updating. A test was performed on synthetic dataset T1014D100K with 100 000 transactions and 870 items. Experimental results show that the smaller the minimum sup- port threshold, the faster the improved pattern tree achieves over CanTree for all datasets. As the minimum support threshold increased from 2% to 3.5%, the runtime decreased from 452.71 s to 186.26 s. Meanwhile, the runtime re- quired by CanTree decreased from 1 367.03 s to 432.19 s. When the database was updated, the execution time of im- proved pattern tree consisted of construction of original improved pattern trees and reconstruction of initial tree. The experiment results showed that the runtime was saved by about 15% compared with that of CanTree. As the number of transactions increased, the runtime of improved pattern tree was about 25% shorter than that of FP-tree. The improved pattern tree also required less memory than CanTree. 相似文献
9.
According to the features of the turning simulation, a simplified Whitted lighting model is proposed based on the analysis of Phong and other local illumination model. Moreover, in order to obtain the natural lighting effects, local ray tracing algorithm is given to calculate the light intensity of every position during the course of the simulation. This method can calculate the refresh area before calculating the intersection line,simulate the machining environment accurately and reduce the calculating time. Finally, an example of the virtual cutting scene is shown to demonstrate the effects of the global illumination model. If the CUP is 1.3 G and the internal memory is 128 M, the refreshing time of virtual turning scene can be reduced by nine times. This study plays an important role in the enrichment of the virtual manufacturing theory and the promotion of the development of the advanced manufacturing technology. 相似文献
10.
Withtherapiddevelopmentofmanufacturingtechnology ,traditionalsimulationofmachiningcannotmeettheneedsofthepeople .Userswanttowatchnotonlythecuttingprocessbetweenthecutterandthesemi finishedpro ducts,butalsothewholemachiningscene .Manyexpertshavefocusedtheirattentiononthisstudy :aframeofvirtualmachiningfordiamondturningbuiltbyCheung[1] caneveninspecttheaccuracyofthework piece ;Zhang[2 ] builtavirtualmachiningcenterandthecorrespondingmeasuringcell;Wang[3] describedandconstructedavirtualcuttingsy… 相似文献