企业生命周期下投资者关注对权益资本成本的影响

基于行为金融学的价格压力假说，结合企业生命周期理论，以2007—2014年的主板上市公司为样本，分析投资者关注对权益资本成本的影响以及这种影响在企业生命周期中存在的阶段性差异。研究发现，投资者关注与权益资本成本显著负相关，即权益资本成本随着投资者关注的提高而降低。对于不同生命周期的企业，投资者关注对权益资本成本的影响存在差异。新生期、衰退期企业的权益资本成本并不会随着投资者关注程度的提高而降低；成长期、成熟期企业的权益资本成本随着投资者关注程度的提高而降低。可以看出，投资者能够识别企业所处的生命周期，并愿意为成长期、成熟期的企业支付更高的溢价。     

A method for recovery of iron,titanium, and vanadium from vanadium-bearing titanomagnetite

An innovative method for recovering valuable elements from vanadium-bearing titanomagnetite is proposed. This method involves two procedures: low-temperature roasting of vanadium-bearing titanomagnetite and water leaching of roasting slag. During the roasting process, the reduction of iron oxides to metallic iron, the sodium oxidation of vanadium oxides to water-soluble sodium vanadate, and the smelting separation of metallic iron and slag were accomplished simultaneously. Optimal roasting conditions for iron/slag separation were achieved with a mixture thickness of 42.5 mm, a roasting temperature of 1200°C, a residence time of 2 h, a molar ratio of C/O of 1.7, and a sodium carbonate addition of 70 wt%, as well as with the use of anthracite as a reductant. Under the optimal conditions, 93.67% iron from the raw ore was recovered in the form of iron nugget with 95.44% iron grade. After a water leaching process, 85.61% of the vanadium from the roasting slag was leached, confirming the sodium oxidation of most of the vanadium oxides to water-soluble sodium vanadate during the roasting process. The total recoveries of iron, vanadium, and titanium were 93.67%, 72.68%, and 99.72%, respectively.     

Mechanical and corrosion properties of low-carbon steel prepared by friction stir processing

Low-carbon steel plates were successfully subjected to normal friction stir processing(NFSP) in air and submerged friction stir processing(SFSP) under water, and the microstructure, mechanical properties, and corrosion behavior of the NFSP and SFSP samples were investigated. Phase transformation and dynamic recrystallization resulted in fine-grained ferrite and martensite in the processed zone. The SFSP samples had smaller ferrites(5.1 μm), finer martensite laths(557 nm), and more uniform distribution of martensite compared to the NFSP samples. Compared to the base material(BM), the microhardness of the NFSP and SFSP samples increased by 19.8% and 27.1%, respectively because of the combined strengthening effects of grain refinement, phase transformation, and dislocation. The ultimate tensile strengths(UTSs) of the NFSP and SFSP samples increased by 27.1% and 38.7%, respectively. Grain refinement and martensite transformation also improved the electrochemical corrosion properties of the low-carbon steel. Overall, the SFSP samples had better mechanical properties and electrochemical corrosion resistance than the NFSP samples.     

张家界大鲵产业集群竞争力测度的AHP-GEMS模型

构建了大鲵产业集群竞争力测度的AHP-GEMS模型，该模型包括四因素对，涵盖八要素.设计了大鲵资源量等34项评价指标，通过层次分析法确定指标权重，并运用GEMS模型对大鲵产业集群竞争力进行定量化测度与评价.以张家界市大鲵产业为例展开分析，结果表明，张家界市大鲵产业集群的竞争力评分为582.55，处于国家一般水平，具有本国范围内较强的集群竞争优势；但张家界市大鲵产业发展存在国内外市场不足、精深加工产业链不完善、从业人员素质与教育水平偏低、产业所在地交通与通讯设施不完善等问题.针对这些问题，提出了加强国内与国际市场融合、基础设施建设与可持续发展融合、产业与全域旅游建设融合、产业发展改革与创新融合等建议.     

Superior corrosion resistance-dependent laser energy density in(CoCrFeNi)95Nb5 high entropy alloy coating fabricated by laser cladding

(CoCrFeNi)95Nb5 high entropy alloy(HEA)coatings were successfully fabricated on a substrate of Q235 steel by laser cladding technology.These(CoCrFeNi)95Nb5 HEA coatings possess excellent properties,particularly corrosion resistance,which is clearly superior to that of some typical bulk HEA and common engineering alloys.In order to obtain appropriate laser cladding preparation process parameters,the effects of laser energy density on the microstructure,microhardness,and corrosion resistance of(CoCrFeNi)95Nb5 HEA coating were closely studied.Results showed that as the laser energy density increases,precipitation of the Laves phase in(CoCrFeNi)95Nb5 HEA coating gradually decreases,and diffusion of the Fe element in the substrate intensifies,affecting the integrity of the(CoCrFeNi)95Nb5 HEA.This decreases the microhardness of(CoCrFeNi)95Nb5 HEA coatings.Moreover,the relative content of Cr2O3,Cr(OH)3,and Nb2O5 in the surface passive film of the coating decreases with increasing energy density,causing corrosion resistance to decrease.This study demonstrates the controllability of a high-performance HEA coating using laser cladding technology,which has significance for the laser cladding preparation of other CoCrFeNi-system HEA coatings.     

投标合谋环境下产业升级的逆向演化研究

投标合谋行为已成为全国性、多领域的群体性违规问题,其存在不仅对我国经济造成了巨大损失,同时也阻碍了行业的健康有序发展.为研究投标合谋行为自身演化规律及其对产业发展的影响,给相关的监管和治理提供参考,本文基于复杂适应系统理论,运用NetLogo多主体仿真平台构建招投标系统并进行演化仿真,最后运用SPSS对所得数据进行回归分析,探索在市场封闭、单纯开放市场、有条件开放市场3种市场情景下合谋比例与报价比例对产业演化过程和结果的影响.研究表明:投标合谋行为会产生"逆向淘汰"效应,不利于降低行业成本,最终导致产业升级逆向演化;合谋行为存在"自我强化"现象;合谋行为会提高合谋者生存几率,但无助于其资本积累;单纯开放市场无助于产业升级,必须配合反合谋审查;现实中应重点对报价比例为0.1到0.3的单位进行合谋审查.     

无人机复垦区植被覆盖度提取方法优选

为探寻无人机遥感对矿业复垦区域植被指数覆盖度的快速提取方法,以四川古蔺某硫磺复垦区为研究对象,通过ZC-6型无人机获取高分辨率遥感影像,采用多种植被指数计算方法作为分类器的选择,使用直方图峰谷法、基本全局阈值法及其融合方法确定图像最佳分割阈值,从而获取研究区植被覆盖度结果.结果表明:不同植被指数分类后的结果有所差异,EXG和VDVI植被指数分类后影像界定较为清晰,而NGBDI指数分类最为模糊;单一直方图峰谷法和基本全局阈值法所得分割结果不理想,而将二者融合后的阈值确定法能结合彼此的优势,弥补灰度不明显或多峰现象的缺点;植被覆盖度(FVC)提取精度显示,基于VDVI提取的人为干预条件下FVC的绝对误差和提取误差分别达到0.0409和7.05％,而基于EXG提取的自然条件下FVC的绝对误差和提取误差分别达到0.0366和6.94％,表明利用VDVI和EXG结合B-H融合的方法可有效用于复垦区条件下的FVC提取.     

基于域适应与分类器差异的滚动轴承跨域故障诊断

基于数据驱动方法诊断滚动轴承故障时，不同工况下的数据特征分布差异会导致模型诊断性能严重下降.针对这一问题，提出了基于域适应与分类器差异的滚动轴承跨域故障诊断方法.首先利用卷积神经网络对带标记的源域样本和无标记的目标域样本进行特征提取;然后通过2个全连接分类器进行故障分类;最后通过分步优化分类损失、域最大平均差异损失和分类器差异损失，实现源域和目标域之间的域分布对齐，从而实现无标记目标域样本的故障诊断.实验结果表明，所提方法与主流的域适应方法相比具有更高故障诊断准确率，验证了该方法的合理性和可行性.     

后疫情背景下武汉创新生态修复与优化研究

2019年底出现的新冠疫情给武汉创新生态带来了明显的冲击,但是同样也带来了新的机遇.本文介绍了创新生态系统的提出和发展历程,梳理了国内外创新生态系统的理论框架及结构相关成果,通过整理分析生态修复相关文献,归纳类比出创新生态系统修复的方法与可行性.采用案例分析方法,通过收集二手数据,分析了武汉光谷创新生态系统受新冠疫情的影响和修复的情况,并结合现有创新生态系统的理论和政府政策,提出了关于武汉创新生态修复与优化的具体对策建议.