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基于余数系统与置换多项式的高速长周期伪随机序列生成方法 被引量:5
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作者 马上 刘剑锋 +2 位作者 杨泽国 张艳 胡剑浩 《电子与信息学报》 EI CSCD 北大核心 2018年第1期42-49,共8页
低复杂度长周期数字伪随机序列在现代加密、通信等系统中具有广泛的应用。该文提出一种基于余数系统和有限域置换多项式的伪随机序列生成方法。该方法基于中国剩余定理将多个互质的小周期有限域随机序列进行单射扩展生成长周期数字伪随... 低复杂度长周期数字伪随机序列在现代加密、通信等系统中具有广泛的应用。该文提出一种基于余数系统和有限域置换多项式的伪随机序列生成方法。该方法基于中国剩余定理将多个互质的小周期有限域随机序列进行单射扩展生成长周期数字伪随机序列,置换多项式的迭代计算在多个并行的小动态范围有限域上进行,从而降低了硬件实现中迭代环路的计算位宽,提高了生成速率。该文还给出构建长周期伪随机序列的置换多项式参数选择方法和中国剩余定理优化方法,在现有技术平台下可轻易实现2^(100)以上的序列周期。同时,该方法具有极大的迭代多项式选择自由度,例如仅在q≡2(mod3)且q≤503的有限域上满足要求的置换多项式就有10905种。硬件实现结构简单,基于Xilinx XC7Z020芯片实现2^(90)的随机序列仅需20个18 kbit的BRAM和少量逻辑资源,无需乘法器,生成速率可达449.236 Mbps。基于NIST的测试表明序列具有良好的随机特性。 展开更多
关键词 伪随机序列 余数系统 置换多项式 高速 长周期 现场可编程逻辑门阵列
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IPO initial returns in China: Underpricing or overvaluation? 被引量:23
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作者 Shunlin Song JinSong Tan Yang Yi 《China Journal of Accounting Research》 2014年第1期31-49,共19页
This paper separates the amount of IPO underpricing(primary market underpricing) and overvaluation(secondary market overvaluation) from the value of an IPO's initial return to evaluate the relative importance of t... This paper separates the amount of IPO underpricing(primary market underpricing) and overvaluation(secondary market overvaluation) from the value of an IPO's initial return to evaluate the relative importance of these two factors and their main determinants. Using data on the IPOs of 948 Chinese firms, we find that average initial returns are 66% and that underpricing and overvaluation are between 14–22% and 44–53%, respectively, depending on the method used to assess firms' intrinsic values. In addition, while both the value of the initial return and the extent of overvaluation are significantly negatively related to post-IPO long-run stock performance, overvaluation can predict post-IPO performance better than the value of the initial return. Value uncertainty in IPOs is positively related to both underpricing and overvaluation, and both the underwriter's reputation and the existence of pricing regulation are positively related to underpricing. Investor sentiment has a positive effect on overvaluation but has no effect or a negative effect on underpricing. Overall, our results suggest that in China overvaluation accounts for a larger proportion of the initial return than underpricing,and that underpricing and overvaluation have different determinants. 展开更多
关键词 IPO initial retum IPO underpricing IPO overvaluation Post-IPO long-rn stock performance Determinants
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