“管理层讨论与分析”(Management’s Discussion and Analysis,MD&A)直接关系到投资者的决策准确性。MD&A中的创新描述与创新投入是否“言行一致”,能否预测企业未来创新绩效,仍是影响投资者决策的重要问题。本研究以2007~202...“管理层讨论与分析”(Management’s Discussion and Analysis,MD&A)直接关系到投资者的决策准确性。MD&A中的创新描述与创新投入是否“言行一致”,能否预测企业未来创新绩效,仍是影响投资者决策的重要问题。本研究以2007~2020年沪深两市A股上市公司14年间16422个非平衡面板数据为样本,首先实证分析MD&A中创新描述与公司创新投入关系,进而检验创新描述对公司未来创新绩效的预测作用。研究发现:(1)创新描述与企业当期创新投入显著正相关,能如实反映企业的创新投入;(2)创新描述能正向预测企业下一年度的专利申请数,但难以预测下一年度的专利授权数,其对企业未来创新绩效的预测作用存在局限。研究结论从文本信息的角度丰富了企业创新绩效的预测方式,有效减轻上市公司内外信息不对称的问题,同时也进一步验证加强“管理层讨论与分析”信息披露内容监管的必要性。展开更多
The understanding of the excitation mechanism of ultra high frequency (UHF) electromagnetic waves (EW) is essential for ap- plying UHF method to partial discharge (PD) detection. Since the EW induced by PD in gas insu...The understanding of the excitation mechanism of ultra high frequency (UHF) electromagnetic waves (EW) is essential for ap- plying UHF method to partial discharge (PD) detection. Since the EW induced by PD in gas insulated switchgear (GIS) contains not only transverse electromagnetic (TEM) wave, but also high-order transverse electric (TE) and high-order transverse magnetic (TM) waves, we analyzed the proportions between the TEM wave and the high order waves, as well as the influence of the PD position on this proportion, using the finite different time domain (FDTD) method. According to the unique characteristics of the waves, they are separated only ap- proximately. It is found that the high-order mode is the main component, more than 70%, of the electric field around the enclosure of GIS, and that with the increasing distance between PD source and inner conductors, the low frequency ( below about 800 MHz) component of EW decreases, but the high frequency component (above 1 GHz) increases, meanwhile the proportion of high-order components in EW could reach 77% from 70%. It concluded that the closer the PD source to the enclosure is, the easier high order EW may be excited.展开更多
文摘“管理层讨论与分析”(Management’s Discussion and Analysis,MD&A)直接关系到投资者的决策准确性。MD&A中的创新描述与创新投入是否“言行一致”,能否预测企业未来创新绩效,仍是影响投资者决策的重要问题。本研究以2007~2020年沪深两市A股上市公司14年间16422个非平衡面板数据为样本,首先实证分析MD&A中创新描述与公司创新投入关系,进而检验创新描述对公司未来创新绩效的预测作用。研究发现:(1)创新描述与企业当期创新投入显著正相关,能如实反映企业的创新投入;(2)创新描述能正向预测企业下一年度的专利申请数,但难以预测下一年度的专利授权数,其对企业未来创新绩效的预测作用存在局限。研究结论从文本信息的角度丰富了企业创新绩效的预测方式,有效减轻上市公司内外信息不对称的问题,同时也进一步验证加强“管理层讨论与分析”信息披露内容监管的必要性。
基金Project supported by National High-tech Research and Development Program of China (863 Program) (2011AA05A121)
文摘The understanding of the excitation mechanism of ultra high frequency (UHF) electromagnetic waves (EW) is essential for ap- plying UHF method to partial discharge (PD) detection. Since the EW induced by PD in gas insulated switchgear (GIS) contains not only transverse electromagnetic (TEM) wave, but also high-order transverse electric (TE) and high-order transverse magnetic (TM) waves, we analyzed the proportions between the TEM wave and the high order waves, as well as the influence of the PD position on this proportion, using the finite different time domain (FDTD) method. According to the unique characteristics of the waves, they are separated only ap- proximately. It is found that the high-order mode is the main component, more than 70%, of the electric field around the enclosure of GIS, and that with the increasing distance between PD source and inner conductors, the low frequency ( below about 800 MHz) component of EW decreases, but the high frequency component (above 1 GHz) increases, meanwhile the proportion of high-order components in EW could reach 77% from 70%. It concluded that the closer the PD source to the enclosure is, the easier high order EW may be excited.
