极大限制边连通超图的两个充分条件

图的限制边连通度是经典边连通度的推广,可用于精确度量网络的容错性.极大限制边连通图是使限制边连通度达到最优的一类图.首先将图的限制边连通度和最小边度的概念推广到r一致线性超图H,证明当H的最小度δ(H)≥r+1时,H的最小边度ξ(H)是它的限制边连通度λ′(H)的一个上界,并将满足ξ(H)=λ′(H)的H称为极大限制边连通超图,然后证明n个顶点的r一致线性超图H如果满足δ(H)≥(n-1)/(2(r-1))+(r-1),则它是极大限制边连通的,最后证明直径为2,围长至少为4的一致线性超图是极大限制边连通的.所得结论是图中相关结果的推广.     

Kantorovich-Like Convergence Theorems for Newton’s Method Using Restricted Convergence Domains

The convergence set for Newton’s method is small in general using Lipschitz-type conditions. A center-Lipschitz-type condition is used to determine a subset of the convergence set containing the Newton iterates. The rest of the Lipschitz parameters and functions are then defined based on this subset instead of the usual convergence set. This way the resulting parameters and functions are more accurate than in earlier works leading to weaker sufficient semi-local convergence criteria. The novelty of the paper lies in the observation that the new Lipschitz-type functions are special cases of the ones given in earlier works. Therefore, no additional computational effort is required to obtain the new results. The results are applied to solve Hammerstein nonlinear integral equations of Chandrasekhar type in cases not covered by earlier works.     

基于改进Faster RCNN的零件识别方法研究北大核心CSCD

针对传统机器视觉检测识别方法受到装配零件之间相互遮挡、零件不同位姿、外部光照强度、小目标漏检影响,检测准确率不高的问题,提出了一种改进的Faster RCNN(region-based convolutional neural networks)零件识别方法。首先使用提取特征更好的ResNet101网络代替原始Faster RCNN模型中的VGG16特征提取网络;其次针对原始候选区域网络,增加2个新的锚点并重新设置候选框的纵横比,以得到15种尺寸不同的锚点;然后针对传统非极大值抑制(non-maximum suppression,NMS)方法因删除交并比大于阈值的候选框而出现漏检问题,使用Soft-NMS方法替换传统的NMS方法,从而减少密集区域漏检的情况;最后在训练模型阶段采用多尺度训练策略,降低漏检率,提高模型准确率。对零件的识别实验结果表明:改进后的Faster RCNN模型能够达到96.1%的精度,较原始模型提升了4.6%,可以满足光照较强、存在水渍干扰等较为复杂环境中零件的识别检测。     

磁性反相限进材料的制备及其应用

以磁性二氧化硅（Fe₂O₃@SiO₂）为基质,利用表面原子转移自由基聚合技术（SI-ATRP）,在改性后的Fe₂O₃@SiO₂内表面接枝甲基丙烯酸十八烷基酯（SMA）、外表面接枝甲基丙烯酸缩甘油酯（GMA）,酸解后得到磁性反相限进材料Fe₂O₃@SiO₂-SMA-GMMA,并通过扫描电镜（SEM）、X射线衍射（XRD）、透射电镜（TEM）、振动样品磁强计（VSM）和元素分析对其进行表征。研究表明,Fe₂O₃@SiO₂-SMA-GMMA对牛血清白蛋白（BSA）的排阻能力为90.4%;对磺胺异恶唑（SIZ）、磺胺二甲氧基嘧啶（SDM）、甲氧苄啶（TMP）和磺胺甲基嘧啶（SMR）的最大吸附量分别为2.76、2.24、1.51和1.34 mg/g。Fe₂O₃@SiO₂-SMA-GMMA应用于牛奶和牛血清样品中SIZ、SMR和SDM的分离富集,SIZ、SMR和SDM的加标回收率为88.7%~90.8%,相对标准偏差为3.3%~5.3%。磁性反相限进材料可简化生物基质样品的前处理过程,对血液样品或食品样品等领域的分析检测具有重要价值。     

Novel Hybrid Benzoazacrown Ligand as a Chelator for Copper and Lead Cations: What Difference Does Pyridine Make

A synthetic procedure for the synthesis of azacrown ethers with a combination of pendant arms has been developed and the synthesized ligand, characterized by various techniques, was studied. The prepared benzoazacrown ether with hybrid pendant arms and its complexes with copper and lead cations were studied in terms of biomedical applications. Similarly to a fully acetate analog, the new one binds both cations with close stability constants, despite the decrease in both constants. The calculated geometry of the complexes correlate with the data from X-ray absorption and NMR spectroscopy. Coordination of both cations differs due to the difference between the ionic radii. However, these chelation modes provide effective shielding of cations in both cases, that was shown by the stability of their complexes in the biologically relevant media towards transchelation and transmetallation.     

Robust Test Statistics Based on Restricted Minimum Rényi’s Pseudodistance Estimators

The Rao’s score, Wald and likelihood ratio tests are the most common procedures for testing hypotheses in parametric models. None of the three test statistics is uniformly superior to the other two in relation with the power function, and moreover, they are first-order equivalent and asymptotically optimal. Conversely, these three classical tests present serious robustness problems, as they are based on the maximum likelihood estimator, which is highly non-robust. To overcome this drawback, some test statistics have been introduced in the literature based on robust estimators, such as robust generalized Wald-type and Rao-type tests based on minimum divergence estimators. In this paper, restricted minimum Rényi’s pseudodistance estimators are defined, and their asymptotic distribution and influence function are derived. Further, robust Rao-type and divergence-based tests based on minimum Rényi’s pseudodistance and restricted minimum Rényi’s pseudodistance estimators are considered, and the asymptotic properties of the new families of tests statistics are obtained. Finally, the robustness of the proposed estimators and test statistics is empirically examined through a simulation study, and illustrative applications in real-life data are analyzed.     

宁波市创建最佳人居环境的优势条件及制约瓶颈

界定了最佳人居环境的概念,并从宏观、中观和微观层面探讨了最佳人居环境的内涵.优越的自然地理条件、快速增长的经济实力、不断提高的社会文明程度、逐步完善的环保法规体系和良好的环境保护工作局面,为宁波市创建最佳人居环境城市奠定了坚实基础,但制约瓶颈也比较突出.通过创建最佳人居环境城市,精心塑造城市个性,提升城市管理水平,优化城市结构,完善城市功能,全面提高城市发展水平,将进一步增强宁波综合实力和国际竞争力.     

Isomorphisms of Galois groups of number fields with restricted ramification

Let K be a number field and S a set of primes of K. We write $K_S/K$ for the maximal extension of K unramified outside S and $G_{K,S}$ for its Galois group. In this paper, we answer the following question under some assumptions: “For $i=1,2$, let $K_i$ be a number field, $S_i$ a (sufficiently large) set of primes of $K_i$ and $\sigma :G_{K_1,S_1}\stackrel{\sim }{\to }{G}_{K_2,S_2}$ an isomorphism. Is σ induced by a unique isomorphism between $K_{1,S_1}/K_1$ and $K_{2,S_2}/K_2$?” Here, the main assumption is about the Dirichlet density of $S_i$.