Browsing by Author "Feng, C."
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Item A General Graph Based Pessimism Reduction Framework For Design Optimization Of Timing Closure(ACM) Peng, F.; Yan, C.; Feng, C.; Zheng, J.; Wang, S. -G; Zhou, Dian; Zeng, X.; Zhou, DianIn this paper, we develop a general pessimism reduction framework for design optimization of timing closure. Although the modified graph based timing analysis (mGBA) slack model can be readily formulated into a quadratic programming problem with constraints, the realistic difficulty is the size of the problem. A critical path selection scheme, a uniform sampling method with the sparse characteristics of the optimal solution, and a stochastic conjugate gradient method are proposed to accelerate the optimization solver. This modified GBA is embedded into design optimization of timing closure. Experimental results show that the proposed solver can achieve 13.82x speedup than gradient descent method with similar accuracy. With mGBA, the optimization of timing closure can achieve a better performance on area, leakage power, buffer counts.Item Self-Assembly of a Conjugated Triblock Copolymer at the Air-Water Interface(2013-06-27) Zhao, L.; Feng, C.; Pang, X.; Jung, J.; Stefan, Mihaela C.; Sista, Prakash; Han, R.; Fang, N.; Lin, Z.; Stefan, Mihaela C.Controlling the self-assembly of highly luminescent conjugated polymers is essential for preparing various optoelectronic devices. In this study, a polyisoprene-b-polystyrene-b-poly(3-hexylthiophene) (PI-PS-P3HT) triblock copolymer was synthesized and readily self-assembled into network-like morphologies via dewetting at the air-water interface. Interestingly, the monolayer thick film displayed high photoluminescence (PL) as a result of successfully transferring the amorphous conjugated P3HT chains in the PI-PS-P3HT triblock copolymer from the solution state to the solid state. A model was proposed to illustrate the supramolecular organization of the PI-PS-P3HT monolayer. To the best of our knowledge, this is the first study of a hydrophobic conjugated block copolymer at the air-water interface, from which the conjugated polymer-based monolayer with highly efficient PL formed by dewetting was achieved.