{"responseHeader":{"status":0,"QTime":8,"params":{"q":"{!q.op=AND}id:\"96061\"","hl":"true","hl.simple.post":"","hl.fragsize":"5000","fq":"!embargo_tdt:[NOW TO *]","hl.fl":"ocr_t","hl.method":"unified","wt":"json","hl.simple.pre":""}},"response":{"numFound":1,"start":0,"docs":[{"modified_tdt":"2015-11-02T00:00:00Z","thumb_s":"/f8/8c/f88c0673e4a2ca081bfd9a84f50169ebb6586913.jpg","oldid_t":"compsci 3879","setname_s":"ir_computersa","file_s":"/30/02/3002def504cb65e8e7fad80906ec02c81cc0559e.pdf","title_t":"Page 23","ocr_t":"13 where t is the family parameter designating the instance of the surfac of the moving solid at timet. It can be shown (7] that the swept volume nv lope is the solution of the system of equations F(x, y, z, t) = 0 :tF(x, y, z, t) = 0 It is hard to find numerical solutions of this system for the general case. Another alternative is to define the family of surfaces parametrically. The family of surfaces can be expressed by R = R( u, v, t). It can be shown [7] that the envelope resulting from sweeping a regular surface satisfies the following condition: 1 a8Ru 8aRv 8aR r1-- o The fact that the Jacobian determinant is singular is utilized to reduce the problem of finding the envelope to finding a set of critical curves, where points appear on both the generator and the envelope. They define the workpiece and fixtures with a solid modeler that uses quadric surfaces and sculptured surfaces. This model is then converted into pixel inforĀmation in the form of a depth-buffer. The swept volume of a tool movement is calculated using the analytical model described above, and then converted to a polyhedral approximation. The polyhedron is then converted to depth-buffer data which have entry-exit pairs for every pixel as seen from the given viewpoint. This can be subtracted from the workpiece depth buffer to simulate the cutting process as shown in Figure 2.4. It has been claimed that this system does realtime simulation on the VAX 11/780 and also supports 5-axis machining. Some of the parts whose N C machining has been simulated using this system are a blisk ( integral blades with disk ) for a jet engine, an aircraft engine case, and a complicated mold with estimated 213000 NC","restricted_i":0,"id":96061,"created_tdt":"2015-11-02T00:00:00Z","format_t":"application/pdf","parent_i":96117,"_version_":1679953695875268609}]},"highlighting":{"96061":{"ocr_t":[]}}}