科创中国

中国宏观经济数据表明,存货总投资对解释GDP波动具有非常重要的作用.进一步利用采购经理人指数(PMI)数据对产成品存货投资和原材料存货投资进行研究,本文发现前者具有逆周期性,而后者表现出顺周期性.本文构建了一个具有产成品和原材料两种存货的动态宏观模型.利用贝叶斯动态方法,对模型进行了整体估计.结果表明,模型动态很好地解释了数据中的经验事实;两类存货投资的周期性特征主要源于最终需求冲击,该结论印证了2008年金融危机中,需求大幅回落是造成中国经济波动的最主要因素.

Pneumatic actuators and electric actuators have almost been applied to all manufacturing industries.The two kinds of actuators can replace each other in most fields,such as the point to point transmission occasion and some rotating occasions.However,there are very few research results about the advantages and disadvantages of two kinds of actuators under the same working conditions so far.In this paper,a novel comprehensive assessment method,named as overall life cycle comprehensive assessment(OLCCA),is proposed for comparison and assessment of pneumatic and electric actuators.OLCCA contains mechanical properties evaluation(MPE),life cycle cost analysis based on users(LCCABOU)and life cycle environmental impact analysis(LCEIA)algorithm in order to solve three difficult problems:mechanical properties assessment,cost analysis and environmental impact assessment about actuators.The mechanical properties evaluation of actuators is a multi-objective optimization problem.The fuzzy data quantification and information entropy methods are combined to establish MPE algorithm of actuators.Two kinds of pneumatic actuators and electric actuators with similar bearing capacity and similar work stroke were taken for example to verify the correctness of MPE algorithm.The case study of MPE algorithm for actuators verified its correctness.LCCABOU for actuators is also set up.Considering cost complex structure of pneumatic actuators,public device cost even method(PDCEM)is firstly presented to solve cost division of public devices such as compressors,aftercooler,receivers,etc.LCCABOU method is also effective and verified by the three groups of pneumatic actuators and electric actuators.Finally,LCEIA model of actuators is established for the environmental impact assessment of actuators.LCEIA data collection method and model establishment procedure for actuators are also put forward.With Simapro 7,LCEIA comparison results of six actuators can be obtained:Fossil fuels are the major environmental factor of pneumatic and electric actuators;Environmental impact of electric actuator is large than one of pneumatic actuator under the similar mechanical properties and working conditions of pneumatic and electric actuators.The results are correct and correspond with the actual mechanical properties of actuators.This paper proposes a comprehensive evaluation method of the actuators,which can solve the critical problem that similar electromechanical products are very difficult to be compared with each other from the angle of performance,cost and environment impact.

The competition of surface and subsurface crack initiation induced failure is critical to understand very high cycle fatigue(VHCF)behavior,which necessitates the elucidation of the underlying mechanisms for the transition of crack initiation from surface to interior defects.Crack initiation potential in materials containing defects is investigated numerically by focusing on defect types,size,shape,location,and residual stress influences.Results show that the crack initiation potency is higher in case of serious property mismatching between matrix and defects,and higher strength materials are more sensitive to soft inclusions(elastic modulus lower than the matrix).The stress localization around inclusions are correlated to interior crack initiation mechanisms in the VHCF regime such as inclusion-matrix debonding at soft inclusions and inclusion-cracking for hard inclusions(elastic modulus higher than the matrix).It is easier to emanate cracks from the subsurface pores with the depth 0.7 times as large as their diameter.There exists an inclusion size independent region for crack incubation,outside which crack initiation will transfer from the subsurface soft inclusion to the interior larger one.As for elliptical inclusions,reducing the short-axis length can decrease the crack nucleation potential and promote the interior crack formation,whereas the long-axis length controls the site of peak stress concentration.The compressive residual stress at surface is helpful to shift crack initiation from surface to interior inclusions.Some relaxation of residual stress can not change the inherent crack initiation from interior inclusions in the VHCF regime.The work reveals the crack initiation potential and the transition among various defects under the influences of both intrinsic and extrinsic factors in the VHCF regime,and is helpful to understand the failure mechanism of materials containing defects under long-term cyclic loadings.

针对传统图像阈值降噪不足,本文提出了无需对噪声方差进行评估的基于主分量分析(Principal Component Analysis,PCA)的第二代Curvelet变换的图像降噪算法,并利用Cycle Spinning技术进行优化.PCA对Curvelet域中的噪声能量进行估计以实现对放射状条纹以及伪吉布斯等不良现象能够有效抑制.仿真试验结果表明,利用本文提出的算法对含噪图像进行降噪,降噪后图像的峰值信噪比得到了显著提高,且视觉效果也得到了明显地改善.因此,本文算法在图像处理领域具有广阔的应用前景.

跪坐是唐代以前中原汉族合乎礼仪的标准坐姿,宋代以后则盛行垂足坐.在小学语文教材中,有部分插图所绘的坐姿不符合历史事实,多将唐代以前流行的跪坐误绘为宋代以后盛行的垂足坐.桌椅等与垂足坐相适应的高足家具唐代以后始普遍流行,在反映唐代以前的历史插图中,不应出现桌椅等家具.中国古代的酒具、茶具和农具,其材质和样式随着时代的发展而有所不同,绘制其插图时,不能有悖于当时的时代背景.

分析商务网站信息生态位的内涵,构造以能力维度、资源维度、关系维度、时间维度和空间维度为主的商务网站信息生态位5维模型,并设计出各生态位维度的指标体系,最后以此指标体系为基础设计出商务网站信息生态位的测度方法.

针对物流信息平台中信息资源采集系统建设的不足,提出建立基于Nutch的网页资源定向采集系统,并对中文分词、主题相关度分析、结果排序、正文解析等关键模块进行重点探讨.最后在一定条件下进行了实验,并分析了实验结果.

以中药鼻炎康提取液、复方珍珠暗疮提取液和VC银翘提取液为研究对象,研究反渗透技术在提取液浓缩过程中的应用.试验结果表明,经反渗透工艺能有效脱水60%以上,中药的主要有效成分保留率达90%,膜通量稳定在14 L/(m2·h),清洗后膜通量恢复80%以上.

高中物理教科书中编入了诸多中国传统文化的素材.通过以应用比较广泛的三个版本的物理教科书中的相关内容为研究对象,进行分析和解读,认为教科书在引入传统文化时,应更多地关注其与学科内容间的联系,充分利用古诗词的魅力,并以多种方式进行展示,将传统文化元素与物理学知识更好地融合,发挥传统文化对物理课程的教育教学功能.