基于典型相关分析的机械故障盲源分离方法研究

提出一种基于典型相关分析的机械故障盲分离方法。与基于独立分量分析的故障盲分离方法相比较,传统的机械故障盲分离方法只考虑样本值的统计分布,不考虑源信号之间的时间和空间关系,而提出的方法克服了此不足,利用源信号的自相关关系来进行盲源分离。仿真结果表明:提出的方法取得了满意的分离效果,并且具有很高的的计算效率,分离速度要快于传统的盲源分离方法。最后,将提出的方法应用到轴承故障诊断中,实验结果进一步验证了该方法的有效性。     

A Chemical Stain for Identifying Arsenic‐Treated Wood Products

Abstract

Convenient and rapid detection of arsenic in treated wood products is necessary when evaluating possible exposure risks from the product during in‐service use and disposal. For this study, a modified stannous chloride stain capable of specifically identifying arsenic in preservative‐treated wood was developed by causing the over‐reduction of molybdenum with stannous chloride prior to sample addition. This reduced the stain's sensitivity to the background phosphate levels in the wood and permitted the detection of elevated arsenate concentrations. The modified stain was confirmed through field testing with weathered wood samples. Alternative application techniques, such as wipes, were further explored.     

Lys53 of Ribosomal Protein L36AL and the CCA End of a tRNA at the P/E Hybrid Site Are in Close Proximity on the Human Ribosome

Previously we have shown that the CCA end of a P‐tRNA can be crosslinked with the RPL36AL protein of the large subunit of mammalian ribosomes; it belongs to the L44e protein family present in all eukaryotic and archaeal ribosomes. Here we confirm and extend this finding and demonstrate that: 1) this crosslink is specific for a tRNA at the P/E hybrid site, as a tRNA in all other tRNA positions of pre‐translocational ribosomes could not be crosslinked with a ribosomal protein, 2) the crosslink was formed most efficiently with C74 and C75 of P/E‐tRNA, but could also connect the ultimate A of this tRNA with Lys53 of protein RPL36AL, 3) this protein contains seven monomethylated residues (three lysyl and three arginyl residues, as well as glutaminyl residue 51), 4) Q51 is part of a conserved GGQ motif in the L44e proteins in eukaryotic 80S ribosomes that is identical to the universally conserved motif of release factors implicated in promoting peptidyl‐tRNA hydrolysis, and 5) the large number of modifications, in which some of the residues were methylated to about 50 %, might indicate that protein RPL36AL is a preferential target for regulation.     

多重CCA算法的柬汉双语词向量构建方法

针对现有双语词向量研究方法获取双语词向量需要用到大量双语平行文本,对于柬汉双语而言存在着平行文本不足的关键问题,而英语作为通用语言,英语-汉语以及英语-柬埔寨语双语平行文本较多且容易获得,因此在典型相关分析跨语言词向量模型上作出进一步改进,提出以英语为中间语言的基于多重CCA算法的汉柬双语词向量构建方法。通过将英语、汉语词向量投影至汉-英向量空间,将英语、柬语词向量投影至柬-英向量空间,根据CCA算法分别得到英-汉、英-柬双语词向量;以英语作为中间词并结合部分实验室构建的柬汉双语电子词典将上一步得到的英-柬、英-汉双语词向量投影至第三方同一向量空间中,再次根据CCA算法得到柬语和汉语在新向量空间中的投影转换矩阵;得到柬英汉多语词向量,多语词向量中包含有柬汉双语词向量。与传统方法相比,该方法解决了当前其他模型所面临的初始柬汉平行文本稀缺的问题,且获得较高的柬汉双语词向量。     

一个高效的选择密文安全的分类代理重加密方案

分类代理重加密通过密码学手段为密文委托与分发提供了高效便捷的解决方案,同时使密文拥有者有能力实施更细粒度的委托控制.本文提出了一种新的分类代理重加密方案,方案在随机预言模型下可证明选择密文安全,相对于现有采用双线性对构造的分类代理重加密方案,我们的无双线性对方案拥有更好的效率,并具备主密钥安全性.     

Jatropha curcas L. (Euphorbiaceae) modulates stomatal traits in response to leaf-to-air vapor pressure deficit

Cultivation of Jatropha curcas in arid and semiarid non-cultivated areas could be a sustainable strategy for stimulating biofuel production without competing with food crops for land and water resources. J. curcas is considered a drought-tolerant species; however, the mechanisms that provide tolerance are unknown. Few efforts have been made to understand the connections between stomatal development and environment conditions. Here, we compared changes in stomatal density (SD) and stomatal index (SI) and their influence on gas exchange in J. curcas. Plants were cultivated in both rainy and dry regions. We describe a distinctive distribution of stomata under the adaxial and abaxial leaf epidermises, where higher SD may have caused the increase in stomatal conductance (g_s) with positive effects on net photosynthetic rate (P_N). However, when rain was excluded, the variation in g_s was strongly related to vapour pressures deficit (VPD), and VPD was strongly related to the P_N. Thus, our results suggest that J. curcas may also contribute mitigating the effect of CO₂ deposition in the atmosphere, given that a remarkable change in SD and other leaf traits was observed in response to seasonal variations. Moreover, multivariate analysis highlights the high sensitivity of J. curcas plants to VPD which in turn induces rapid stomatal closure and consequent reduction of P_N for long periods of time which reflect into a change in the pattern of development resulting in higher SI. These results can help us to understand the relationship between stomatal features and gas exchange in response to environment changes.     

基于格上带舍入学习问题的抗选择密文攻击的公钥密码体制

基于格的密码体制具有可抵抗目前已知量子算法攻击、并行性好、由格上困难问题确保的可证安全性等优点,具有广泛的应用前景,受到了越来越多的关注.带舍入学习问题（learn-ing with rounding问题,LWR问题）作为格上新兴问题,相关工作较少,研究价值较高.文章提出了两种基于该问题的公钥加密体制,给出了在随机谕示模型下的安全性证明.与现有基于该问题的体制相比,新体制可以达到适应性选择密文攻击下不可区分性（IND-CCA2）的安全性.     

Mo_2C/CCA催化剂制备及环己烷脱氢性能研究

以(NH4)6Mo7O24.4H2O为钼源,以覆炭γ-Al2O3(CCA)为载体,采用浸渍法制备出催化剂前驱物Mo3O/CCA。以正己烷为渗碳剂对前驱物进行碳化得到Mo2C/CCA。对不同碳化终温下制得的催化剂进行了XRD表征。在固定床反应装置上进行了环己烷脱氢反应,考察了催化剂的制备条件及反应条件对催化剂脱氢活性的影响。结果表明:当载体CCA覆炭量为7.82%,碳化终温为650℃,反应条件为温度475℃、压力0.1 MPa、空速2h-1、氢烃体积比200∶1时,环己烷的转化率最高可达91%。     

基于2D-FrFT多阶次特征融合的人脸表情识别方法

提出一种二维分数阶傅里叶域(2D-FrFT)多阶次特征融合分类算法.该方法充分利用分数阶傅里叶域不同阶次下表情特征之间的相关性,选取两个阶次的表情特征,利用典型相关分析法(Canonical Correlation Analysis,CCA)进行特征融合,并通过基于支持向量机(Support Vector Machine,SVM)的多层次分类机制进行人脸表情识别.仿真实验结果表明,采用多阶次特征融合算法后提高了平均识别率,降低了表情特征维数,减小了计算量.