本文是结合国防科大微电子所项目要求对X-D SP处理器中ALU的加法器设计进行了详细论述,回顾了经典的加法器算法,提出了包含进位选择和超前进位两种思想的等延时结构,对40位全定制加法器的算法进行了改进。本文的研究成果包括如下一些方...本文是结合国防科大微电子所项目要求对X-D SP处理器中ALU的加法器设计进行了详细论述,回顾了经典的加法器算法,提出了包含进位选择和超前进位两种思想的等延时结构,对40位全定制加法器的算法进行了改进。本文的研究成果包括如下一些方面:以跳跃进位加法器为基础,对加法器的低16位附加一条超前进位连来减小进位延迟时间;在分析ALU的结构基础下,对ALU采用了并行结构,使ALU可以工作在双16位模式下;通过模块分析,将数字运算控制与逻辑运算控制整合在一起,减少了芯片面积,提高了运算速度。完成设计后,通过使用S IM V IW E来观察波形,进行了模块级功能验证和系统级功能验证。展开更多
As complex traits evolve, each component of the trait may be under different selection pressures and could respond independently to distinct evolutionary forces. We used comparative methods to examine patterns of evol...As complex traits evolve, each component of the trait may be under different selection pressures and could respond independently to distinct evolutionary forces. We used comparative methods to examine patterns of evolution in multiple components of a complex courtship signal in darters, specifically addressing the question of how nuptial coloration evolves across different areas of the body. Using spectral reflectance, we defined 4 broad color classes present on the body and fins of 17 species of freshwater fishes （genus Etheostoma） and quantified differences in hue within each color class. Ancestral state reconstruction suggests that most color traits were expressed in the most recent common ancestor of sampled species and that differences among species are mostly due to losses in coloration. The evolutionary lability of coloration varied across body regions; we found sig- nificant phylogenetic signal for orange color on the body but not for most colors on fins. Finally, patterns of color evolution and hue Of the colors were correlated among the two dorsal fins and between the anterior dorsal and anal fins, but not between any of the fins and the body. The observed patterns support the hypothesis that different components of complex signals may be subject to distinct evolutionary pressures, and suggests that the combination of behavioral displays and morphology in communication may have a strong influence on patterns of signal evolution .展开更多
文摘本文是结合国防科大微电子所项目要求对X-D SP处理器中ALU的加法器设计进行了详细论述,回顾了经典的加法器算法,提出了包含进位选择和超前进位两种思想的等延时结构,对40位全定制加法器的算法进行了改进。本文的研究成果包括如下一些方面:以跳跃进位加法器为基础,对加法器的低16位附加一条超前进位连来减小进位延迟时间;在分析ALU的结构基础下,对ALU采用了并行结构,使ALU可以工作在双16位模式下;通过模块分析,将数字运算控制与逻辑运算控制整合在一起,减少了芯片面积,提高了运算速度。完成设计后,通过使用S IM V IW E来观察波形,进行了模块级功能验证和系统级功能验证。
基金Acknowledgements We thank Michael Martin, Tory Williams, and Alex Nahm for assistance in collecting fishes and the Mendelson lab for assistance in fish maintenance. We thank Chioma Ihekweazu for assistance with spectral analysis. We also thank Karen Carleton for use of the software to calculate spectral location. Tom Cronin, Kevin Omland, Megan Porter, Kate Feller, Nick Friedman and Brian Dalton provided helpful discussions throughout the course of this work. We thank two anonymous reviewers and the editor for their helpful comments on previous versions of this manuscript. We especially thank Eileen Hebets for the invitation to submit to this special issue. This work was funded through a National Science Foundation grant to TCM （#DEB 0718987）. Additional support for this work came from the NSF, NCEAS and NESCENT funded ＂Comparative Phylogenetics in R＂ workshop attended by JMG.
文摘As complex traits evolve, each component of the trait may be under different selection pressures and could respond independently to distinct evolutionary forces. We used comparative methods to examine patterns of evolution in multiple components of a complex courtship signal in darters, specifically addressing the question of how nuptial coloration evolves across different areas of the body. Using spectral reflectance, we defined 4 broad color classes present on the body and fins of 17 species of freshwater fishes （genus Etheostoma） and quantified differences in hue within each color class. Ancestral state reconstruction suggests that most color traits were expressed in the most recent common ancestor of sampled species and that differences among species are mostly due to losses in coloration. The evolutionary lability of coloration varied across body regions; we found sig- nificant phylogenetic signal for orange color on the body but not for most colors on fins. Finally, patterns of color evolution and hue Of the colors were correlated among the two dorsal fins and between the anterior dorsal and anal fins, but not between any of the fins and the body. The observed patterns support the hypothesis that different components of complex signals may be subject to distinct evolutionary pressures, and suggests that the combination of behavioral displays and morphology in communication may have a strong influence on patterns of signal evolution .
