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91.
上市公司治理结构对内部控制的影响研究 总被引:1,自引:0,他引:1
以我国沪市100家制造业上市公司为研究对象,考察了公司治理结构对内部控制的单向影响。实证研究发现,第一大股东持股比例、独立董事比例、董事会会议次数等对上市公司内部控制效果有显著影响。提高上市公司内部控制效果应从公司治理结构的角度出发,具体措施包括:建立健全约束大股东行为的相关机制;继续完善独立董事制度,提高董事会的独立性;加强董事和董事会的问责制度建设。 相似文献
92.
93.
PU YiFei SIARRY Patrick ZHOU JiLiu LIU YiGuang ZHANG Ni HUANG Guo LIU YiZhi 《中国科学:信息科学(英文版)》2014,(7):180-198
In this paper,a set of fractional partial differential equations based on fractional total variation and fractional steepest descent approach are proposed to address the problem of traditional drawbacks of PM and ROF multi-scale denoising for texture image.By extending Green,Gauss,Stokes and Euler-Lagrange formulas to fractional field,we can find that the integer formulas are just their special case of fractional ones.In order to improve the denoising capability,we proposed 4 fractional partial differential equation based multiscale denoising models,and then discussed their stabilities and convergence rate.Theoretic deduction and experimental evaluation demonstrate the stability and astringency of fractional steepest descent approach,and fractional nonlinearly multi-scale denoising capability and best value of parameters are discussed also.The experiments results prove that the ability for preserving high-frequency edge and complex texture information of the proposed denoising models are obviously superior to traditional integral based algorithms,especially for texture detail rich images. 相似文献
94.
研究了含负折射率介质的一维光子晶体的反射特性和用其制作全向反射镜的物理基础,同时研究了此种光子晶体PBG的影响因素.研究发现,周期结构参致--晶格常数和层厚畸变对含负折射率材料的一维光子晶体的PBG几乎没有影响.在一定频城内可实现全向反射. 相似文献
95.
在梯度胶片制作系统的设计中,为了完成制胶系统上位机数据计算、图形显示、系统管理软件的设计,采用Matlab函数根据采样数据合出步进电机进给控制曲线,结合VB将曲线和数据显示在人机交互界面上,将所计算的参数提供给下位控制系统,系统通过曲线插补计算对步进电机进行控制来完成胶片制作.经实践检验,这种方法所设计的监控程序功能完善、界面良好、操作方便. 相似文献
96.
油气井钻进破岩过程发生于地下几千米,难以获取井底钻具组合的运动状态.井底钻具组合与岩石的相互作用产生多种形式的振动及振动的耦合.为进一步研究破岩引发钻进中振动的产生机理,建立了井底钻具组合钻铤段非线性动力学模型,通过数值仿真,分析了破岩过程中转速、钻井液、井底钻具组合偏心距、摩擦等对钻铤段旋转进动的影响.数值研究表明,系统参数的变化导致井底钻具组合进动轨迹的多样性和不可预测性;井底钻具组合受到外力作用,导致钻铤进动出现混沌;钻进过程中钻铤与井壁间会发生周期性碰摩现象,为研究钻进引发钻柱黏滑振动提供新的研究思路. 相似文献
97.
The effects of CaO and Na2CO3 on the reduction of high silicon iron ores at 1 250 °C were studied. The experimental results showed that the metallization rate was significantly hindered by the addition of CaO and Na2CO3, particularly at the early stage of roasting, compared to the rate without additives. In the absence of additives, iron oxides were quickly reduced to metallic iron, and fayalite was difficult to form. When CaO and Na2CO3 were added, the low reducible iron-containing silicate compounds formed and melted, subsequently retarding the metallization process. The inhibition of Na2CO3 was more noticeable than that of CaO, and higher Na2CO3 doses resulted in stronger inhibition of the increased metallization rate. However, when Na2CO3 was added prior to CaO, the liquid phase formed, which facilitated the growth of the metallic phase. To reinforce the separation of the metallic phase and slag, an appropriate amount of liquid phase generated during the reduction is necessary. It was shown that when 10% CaO and 10% Na2CO3 were added, a high metallization rate and larger metallic iron particles were obtained, thus further decreasing the required Na2CO3 dosage. 相似文献
98.
物流业是国民经济的重要组成部分,首先基于主成分分析法提取区域物流投入与产出的主要指标,然后建立基于DEA方法的区域物流发展效率评价指标与模型。进而将PCA和DEA分析法用于湖北省十堰市区域物流发展效率的实证研究中,根据所构建的评价指标与模型测算十堰市1995-2013年19个年度的物流发展效率,分析了十堰市各年度物流业的投入与产出不足,并为十堰市提出区域物流发展的建议。 相似文献
99.
New visible transparent, UV absorption, and high infrared reflection properties have been realized by depositing multilayer SiO2/ZnO: Al/CeO2-TiO2/SiO2 films onto glass substrates at low temperature by radio frequency magnetron sputtering. Optimum thickness of SiO2, ZnO: Al (ZAO) and CeO2-TiO2 (CTO) films were designed with the aid of thin film design software. The degree of antireflection can be controlled by adjusting the thickness and refractive index. The outer SiO2 film can diminish the interference coloring and increase the transparency; the inner SiO2 film improves the adhesion of the coating on the glass substrate and prevents Ca2+, Na+ in the glass substrate from entering the ZAO film. The average transmittance in the visible light range increases by nearly 18%-20%, as compared to double layer ZAO/CTO films. And the films display high infrared reflection rate of above 75% in the wavelength range of 10-25 μm and good UV absorption (> 98%) properties. These systems are easy to produce on a large scale at low cost and exhibit high mechanical and chemical durability. The triple functional films with high UV absorption, antireflective and high infrared reflection rate will adapt to application in flat panel display and architectural coating glass, automotive glass, with diminishing light pollution as well as decreasing eye fatigue and increasing comfort. 相似文献
100.
There were differences between real boundary and blast hole controlling boundary of irregular mined-out area in underground metal mines. There were errors in numerical analysis of stability for goaf, if it was analyzed as regular 3D mined-out area and the influence of coupling stress-seepage-disturbance was not considered adequately. Taking a lead zinc mine as the background, the model was built by the coupling of Surpac and Midas-Gts based on the goaf model precisely measured by CMS.According to seepage stress fundamental equations based on the equivalent continuum mechanical and the theory about equivalent load of dynamic disturbance in deep-hole blasting, the stability of mined-out area under multi-field coupling of stress-seepage-dynamic disturbance was numerically analyzed. The results show that it is more consistent between the numerical analysis model based on the real model of irregular 3D shape goaf and the real situation, which could faithfully reappear the change rule of stress–strain about the surrounding rock under synthetic action of blasting dynamic loading and the seepage pressure. The mined-out area multi-field coupling formed by blasting excavation is stable. Based on combination of the advantages of the CMS,Surpac and Midas-Gts, and fully consideration of the effects of multi-field coupling, the accurate and effective way could be provided for numerical analysis of stability for mined-out area. 相似文献