随着可复用容器(returnable transport items,RTI)广泛应用于汽车制造业,RTI的管理对于汽车零部件生产物流系统的正常运行具有重要影响。本文考虑从上线订单到达与负责拣选的RTI进行匹配开始,到零部件上线RTI返还结束全过程,通过构建半...随着可复用容器(returnable transport items,RTI)广泛应用于汽车制造业,RTI的管理对于汽车零部件生产物流系统的正常运行具有重要影响。本文考虑从上线订单到达与负责拣选的RTI进行匹配开始,到零部件上线RTI返还结束全过程,通过构建半开闭排队网络,选取订单排队队长以及RTI利用率两个指标研究在此过程中RTI的数量以及RTI的返还提前期对于系统均衡性的影响。分析表明,RTI的数量和返还提前期都对系统的均衡性带来较大影响,同时,通过模型可以得出具体场景下RTI数量和返还提前期的最优值,使得系统外部无等待的订单积压,到来订单无需排队等待拣选,RTI的利用率能够接近于100%避免资源浪费,从而提高零部件物流系统的均衡性。展开更多
2wt%TiB_(2)/Cu composite powders were fabricated in situ by reactive gas atomization.The fabricated composite powder exhibits high sphericity,and the powder sizes range from 5μm to 150μm.The morphology of the Cu mat...2wt%TiB_(2)/Cu composite powders were fabricated in situ by reactive gas atomization.The fabricated composite powder exhibits high sphericity,and the powder sizes range from 5μm to 150μm.The morphology of the Cu matrix and the distribution of the TiB2 particles in the composite powders vary with the powder size.The critical transitions of interface morphologies from dendritic-to-cellular and cellular-to-planar interfaces occurs when the composite powder sizes decrease to 34μm and 14μm,respectively.Compared with pure Cu droplets,the composite droplets undergo critical transition of the interface morphologies at a smaller droplet size corresponding to a higher cooling rate because the existence of TiB2 particles can cause instability in the advancing solidification front and heterogeneous nucleation.With decreasing powder size,the extent of the TiB_(2) particle interdendritic segregation decreases as the result of enhanced engulfment of TiB2 particles by the advancing solidification front.展开更多
The composite field multiplication is an important and complex module in symmetric cipher algorithms, and its realization performance directly restricts the processing speed of symmetric cipher algorithms. Based on th...The composite field multiplication is an important and complex module in symmetric cipher algorithms, and its realization performance directly restricts the processing speed of symmetric cipher algorithms. Based on the characteristics of composite field multiplication in symmetric cipher algorithms and the realization principle of its reconfigurable architectures, this paper describes the reconfigurable composite field multiplication over GF（（2^8）k） （k=1,2,3,4） in RISC （reduced instruction set computer） processor and VLIW （very long instruction word） processor architecture, respectively. Through configuration, the architectures can realize the composite field multiplication over GF（2^8）, GF （（2^8）2）, GF（（28）3） and GF（（28）4） flexibly and efficiently. We simulated the function of circuits and synthesized the reconfigurable design based on the 0.18 μm CMOS （complementary metal oxide semiconductor） standard cell library and the comparison with other same kind designs. The result shows that the reconfigurable design proposed in the paper can provide higher efficiency under the premise of flexibility.展开更多
文摘随着可复用容器(returnable transport items,RTI)广泛应用于汽车制造业,RTI的管理对于汽车零部件生产物流系统的正常运行具有重要影响。本文考虑从上线订单到达与负责拣选的RTI进行匹配开始,到零部件上线RTI返还结束全过程,通过构建半开闭排队网络,选取订单排队队长以及RTI利用率两个指标研究在此过程中RTI的数量以及RTI的返还提前期对于系统均衡性的影响。分析表明,RTI的数量和返还提前期都对系统的均衡性带来较大影响,同时,通过模型可以得出具体场景下RTI数量和返还提前期的最优值,使得系统外部无等待的订单积压,到来订单无需排队等待拣选,RTI的利用率能够接近于100%避免资源浪费,从而提高零部件物流系统的均衡性。
基金Funded by the National Natural Science Foundation of China(Nos.U1502274 and 51834009)。
文摘2wt%TiB_(2)/Cu composite powders were fabricated in situ by reactive gas atomization.The fabricated composite powder exhibits high sphericity,and the powder sizes range from 5μm to 150μm.The morphology of the Cu matrix and the distribution of the TiB2 particles in the composite powders vary with the powder size.The critical transitions of interface morphologies from dendritic-to-cellular and cellular-to-planar interfaces occurs when the composite powder sizes decrease to 34μm and 14μm,respectively.Compared with pure Cu droplets,the composite droplets undergo critical transition of the interface morphologies at a smaller droplet size corresponding to a higher cooling rate because the existence of TiB2 particles can cause instability in the advancing solidification front and heterogeneous nucleation.With decreasing powder size,the extent of the TiB_(2) particle interdendritic segregation decreases as the result of enhanced engulfment of TiB2 particles by the advancing solidification front.
基金Supported by the National Natural Science Foundation of China(61202492,61309022,61309008)the Natural Science Foundation for Young of Shaanxi Province(2013JQ8013)
文摘The composite field multiplication is an important and complex module in symmetric cipher algorithms, and its realization performance directly restricts the processing speed of symmetric cipher algorithms. Based on the characteristics of composite field multiplication in symmetric cipher algorithms and the realization principle of its reconfigurable architectures, this paper describes the reconfigurable composite field multiplication over GF（（2^8）k） （k=1,2,3,4） in RISC （reduced instruction set computer） processor and VLIW （very long instruction word） processor architecture, respectively. Through configuration, the architectures can realize the composite field multiplication over GF（2^8）, GF （（2^8）2）, GF（（28）3） and GF（（28）4） flexibly and efficiently. We simulated the function of circuits and synthesized the reconfigurable design based on the 0.18 μm CMOS （complementary metal oxide semiconductor） standard cell library and the comparison with other same kind designs. The result shows that the reconfigurable design proposed in the paper can provide higher efficiency under the premise of flexibility.
