The choice of the sequence in which parts or subass em blies are put together in the mechanical assembly of a product can drastical ly affect the efficiency of the assembly process. Unlike metal cutting operation s wh...The choice of the sequence in which parts or subass em blies are put together in the mechanical assembly of a product can drastical ly affect the efficiency of the assembly process. Unlike metal cutting operation s where computer aided system have been available for some 15 to 25 years to hel p manufacturing engineers in generating cutting sequences and NC programs, the m ajority of assembly planning tasks in automobile body design is still manually p erformed by assembly designers according to their past experiences. This has prolonged the production lead time and time to market. This paper describes a p rocedure to automatically derive all the feasible assembly sequences for automob ile body assembly. The procedure is based on a mathematical model of the automob ile body, obtained through the definitions of the connection matrix and contract ed matrix. These two matrices represent the precedence constraint knowledge amon g components and subassemblies. The possible subassemblies are automatically det ected by satisfying some mathematical conditions applicable to these matrices. F or each subassembly and the whole product, all the possible assembly sequences a re generated by rearranging the initial connection sub-matrix and the contracte d matrix. The procedure is applicable to compliant component assemblies, suc h as the automobile body assembly, aircraft frame assembly, and can solve the "combinatorial explosion" problem efficiently.展开更多
An 8×10 GHz receiver optical sub-assembly （ROSA） consisting of an 8-channel arrayed waveguide grating （AWG） and an 8-channel PIN photodetector （PD） array is designed and fabricated based on silica hybrid in...An 8×10 GHz receiver optical sub-assembly （ROSA） consisting of an 8-channel arrayed waveguide grating （AWG） and an 8-channel PIN photodetector （PD） array is designed and fabricated based on silica hybrid integration technology. Multimode output waveguides in the silica AWG with 2% refractive index difference are used to obtain fiat-top spectra. The output waveguide facet is polished to 45° bevel to change the light propagation direction into the mesa-type PIN PD, which simplifies the packaging process. The experimentM results show that the single channel I dB bandwidth of AWG ranges from 2.12nm to 3.06nm, the ROSA responsivity ranges from 0.097 A/W to 0.158A/W, and the 3dB bandwidth is up to 11 GHz. It is promising to be applied in the eight-lane WDM transmission system in data center interconnection.展开更多
文摘The choice of the sequence in which parts or subass em blies are put together in the mechanical assembly of a product can drastical ly affect the efficiency of the assembly process. Unlike metal cutting operation s where computer aided system have been available for some 15 to 25 years to hel p manufacturing engineers in generating cutting sequences and NC programs, the m ajority of assembly planning tasks in automobile body design is still manually p erformed by assembly designers according to their past experiences. This has prolonged the production lead time and time to market. This paper describes a p rocedure to automatically derive all the feasible assembly sequences for automob ile body assembly. The procedure is based on a mathematical model of the automob ile body, obtained through the definitions of the connection matrix and contract ed matrix. These two matrices represent the precedence constraint knowledge amon g components and subassemblies. The possible subassemblies are automatically det ected by satisfying some mathematical conditions applicable to these matrices. F or each subassembly and the whole product, all the possible assembly sequences a re generated by rearranging the initial connection sub-matrix and the contracte d matrix. The procedure is applicable to compliant component assemblies, suc h as the automobile body assembly, aircraft frame assembly, and can solve the "combinatorial explosion" problem efficiently.
基金Supported by the National High Technology Research and Development Program of China under Grant No 2015AA016902the National Natural Science Foundation of China under Grant Nos 61435013 and 61405188the K.C.Wong Education Foundation
文摘An 8×10 GHz receiver optical sub-assembly （ROSA） consisting of an 8-channel arrayed waveguide grating （AWG） and an 8-channel PIN photodetector （PD） array is designed and fabricated based on silica hybrid integration technology. Multimode output waveguides in the silica AWG with 2% refractive index difference are used to obtain fiat-top spectra. The output waveguide facet is polished to 45° bevel to change the light propagation direction into the mesa-type PIN PD, which simplifies the packaging process. The experimentM results show that the single channel I dB bandwidth of AWG ranges from 2.12nm to 3.06nm, the ROSA responsivity ranges from 0.097 A/W to 0.158A/W, and the 3dB bandwidth is up to 11 GHz. It is promising to be applied in the eight-lane WDM transmission system in data center interconnection.
