The cold semi-precision forging of a multi-row sprocket was investigated using upper-bound （UB） and finite element methods combined with experiments. Based on the design of a new tooth profile for the sprocket, a co...The cold semi-precision forging of a multi-row sprocket was investigated using upper-bound （UB） and finite element methods combined with experiments. Based on the design of a new tooth profile for the sprocket, a cold semi-precision forging process and a kinematically admissible velocity field for filling the die cavity were proposed. Using the UB method, the velocity fields of the sprocket billet in the forming process were divided theoretically and calculated. The process of forging a multi-row sprocket was simulated using the FEM package Deform-3D V6.1 to obtain the distributions of the velocity field and the effective stress field in filling the die cavity. Similar to the simulated results, the experiment on cold forging a 5052 aluminum alloy sprocket was successfully performed. By comparing the calculated （UB method）, experimental and simulated load-stroke curves, the calculated and simulated results were basically in accordance with the experimental results. The study provides a theoretical foundation for the development of the precision forging of multi-row sprockets.展开更多
For the first time, we introduce a fully quantum mechanical Hamiltonian for a semi-infinite chain model of atoms. We then derive the vibration modes of this model by virtue of the ＂invariant eigen-operator＂ method i...For the first time, we introduce a fully quantum mechanical Hamiltonian for a semi-infinite chain model of atoms. We then derive the vibration modes of this model by virtue of the ＂invariant eigen-operator＂ method in two different cases, which is concise and revealing.展开更多
The dynamic network loading problem (DNLP) consists in determining on a congested network, time-dependent arc volumes, together with arc and path travel times, given the time varying path flow departure rates over a f...The dynamic network loading problem (DNLP) consists in determining on a congested network, time-dependent arc volumes, together with arc and path travel times, given the time varying path flow departure rates over a finite time horizon. The objective of this pap er is to present the formulation of an analytical dynamic multi-class network loading model. The mo del does not require the assumption of the FIFO condition. The existence of a solution to the model is shown.展开更多
文摘The cold semi-precision forging of a multi-row sprocket was investigated using upper-bound （UB） and finite element methods combined with experiments. Based on the design of a new tooth profile for the sprocket, a cold semi-precision forging process and a kinematically admissible velocity field for filling the die cavity were proposed. Using the UB method, the velocity fields of the sprocket billet in the forming process were divided theoretically and calculated. The process of forging a multi-row sprocket was simulated using the FEM package Deform-3D V6.1 to obtain the distributions of the velocity field and the effective stress field in filling the die cavity. Similar to the simulated results, the experiment on cold forging a 5052 aluminum alloy sprocket was successfully performed. By comparing the calculated （UB method）, experimental and simulated load-stroke curves, the calculated and simulated results were basically in accordance with the experimental results. The study provides a theoretical foundation for the development of the precision forging of multi-row sprockets.
基金The project supported by the President Foundation of the Chinese Academy of Sciences
文摘For the first time, we introduce a fully quantum mechanical Hamiltonian for a semi-infinite chain model of atoms. We then derive the vibration modes of this model by virtue of the ＂invariant eigen-operator＂ method in two different cases, which is concise and revealing.
基金Shanghai Leading Academic Discipline Pro-ject (No.T0602)
文摘The dynamic network loading problem (DNLP) consists in determining on a congested network, time-dependent arc volumes, together with arc and path travel times, given the time varying path flow departure rates over a finite time horizon. The objective of this pap er is to present the formulation of an analytical dynamic multi-class network loading model. The mo del does not require the assumption of the FIFO condition. The existence of a solution to the model is shown.
