A new approach of incremental placement approach is described.The obtained timing information drives an efficient net-based placement technique,which dynamically adapts the net weights during successive placement step...A new approach of incremental placement approach is described.The obtained timing information drives an efficient net-based placement technique,which dynamically adapts the net weights during successive placement steps.Several methods to combine timing optimization and congestion reducing together are proposed.Cells on critical paths are replaced according to timing and congestion constraints.Experimental results show that our approach can efficiently reduce cycle time and enhance route ability.The max path delay is reduced by 10% on an average afterincremental placement on wirelength-optimized circuits.And it achieves the same quality with a high speed up compared to timing driven detailed placement algorithm.展开更多
This paper attempts to introduce an improved difference model that modifies a car-following model, which takes the next-nearest-neighbor interaction into account. The hnprovement of this model over the previous one li...This paper attempts to introduce an improved difference model that modifies a car-following model, which takes the next-nearest-neighbor interaction into account. The hnprovement of this model over the previous one lies in that it performs more realistically in the dynamical motion for small delay time. The traffic behavior of the improved model is investigated with analytic and numerical methods with the finding that the new consideration could further stabilize traffic flow. And some simulation tests verify that the proposed model can demonstrate some complex physical features observed recently in real traffic such as the existence of three phases： free flow, coexisting flow, and jam flow; spontaneous formation of density waves; sudden flow drop in flow-density plane; traffic hysteresis in transition between the free and the coexisting flow. Furthermore, th.e improved model also predicts that the stable state to relative density in the coexisting flow is insusceptible to noise.展开更多
The expansion mechanism inside carbon dioxide expander is analyzed theoretically in this paper.The mechanism analysis of metastable equilibrium indicates that there is a potential barrier during phase change process.T...The expansion mechanism inside carbon dioxide expander is analyzed theoretically in this paper.The mechanism analysis of metastable equilibrium indicates that there is a potential barrier during phase change process.That is to say energy is required to overcome the potential barrier when the new interface is formed from primary phase.The superheat of liquid is the impetus of phase change and has an exponential decrease with the increase of the saturated temperature of fluid.The analysis also indicates that there is a critical radius during the phase change process.The bubble will grow up when its radius is larger than the critical value,otherwise,will disappear.When considering the metastable phase change,calculation of P and V during expansion process indicates that the phase-change will be delayed with the decline of pressure,which is called lag phenomenon.The phase-change delay time decreases with the increase of initial temperature.When the initial temperature is close to the critical temperature,the delay time is close to zero.The phase-change delay brings energy losses,which decrease with the increase of initial temperature and its decrease ratio also has a decrease trend.When the initial pressure is 10 MPa,the energy loss will be 1.06 W with an initial temperature of 10℃ while 0.34 W with that of 20℃.展开更多
文摘A new approach of incremental placement approach is described.The obtained timing information drives an efficient net-based placement technique,which dynamically adapts the net weights during successive placement steps.Several methods to combine timing optimization and congestion reducing together are proposed.Cells on critical paths are replaced according to timing and congestion constraints.Experimental results show that our approach can efficiently reduce cycle time and enhance route ability.The max path delay is reduced by 10% on an average afterincremental placement on wirelength-optimized circuits.And it achieves the same quality with a high speed up compared to timing driven detailed placement algorithm.
基金The project supported by the Key Foundation Project of Shanghai under Grant No. 032912066
文摘This paper attempts to introduce an improved difference model that modifies a car-following model, which takes the next-nearest-neighbor interaction into account. The hnprovement of this model over the previous one lies in that it performs more realistically in the dynamical motion for small delay time. The traffic behavior of the improved model is investigated with analytic and numerical methods with the finding that the new consideration could further stabilize traffic flow. And some simulation tests verify that the proposed model can demonstrate some complex physical features observed recently in real traffic such as the existence of three phases： free flow, coexisting flow, and jam flow; spontaneous formation of density waves; sudden flow drop in flow-density plane; traffic hysteresis in transition between the free and the coexisting flow. Furthermore, th.e improved model also predicts that the stable state to relative density in the coexisting flow is insusceptible to noise.
基金supported by the National Natural Science Foundation of China (Grant No 50676064)
文摘The expansion mechanism inside carbon dioxide expander is analyzed theoretically in this paper.The mechanism analysis of metastable equilibrium indicates that there is a potential barrier during phase change process.That is to say energy is required to overcome the potential barrier when the new interface is formed from primary phase.The superheat of liquid is the impetus of phase change and has an exponential decrease with the increase of the saturated temperature of fluid.The analysis also indicates that there is a critical radius during the phase change process.The bubble will grow up when its radius is larger than the critical value,otherwise,will disappear.When considering the metastable phase change,calculation of P and V during expansion process indicates that the phase-change will be delayed with the decline of pressure,which is called lag phenomenon.The phase-change delay time decreases with the increase of initial temperature.When the initial temperature is close to the critical temperature,the delay time is close to zero.The phase-change delay brings energy losses,which decrease with the increase of initial temperature and its decrease ratio also has a decrease trend.When the initial pressure is 10 MPa,the energy loss will be 1.06 W with an initial temperature of 10℃ while 0.34 W with that of 20℃.
