具有单参数空间对称群的向量场及其约化

对于保持某n-形式的n维向量场，应用Lie群的方法得到结论：当这类向量场有保持n-形式的空间参数对称群时，可具体地构造出一个与该向量场无关的变换，它不仅使向量场约化掉一维，并且使得约化向量场保持相应的(n-1)-形式。特别，当n=3时，简单地得到了Mezie和Wiggins最近得到的重要结果

An Intrusion Detection Method Based on Clustering and Association Correction

针对目前基于k-MEAnS算法的入侵检测技术所存在的符号类型数据处理能力欠缺、误报率较高的问题,提出了一种基于聚类和关联规则修正的入侵检测技术。将关联规则挖掘技术引入到聚类分析机制中,利用针对符号型属性的关联规则挖掘结果对聚类结果进行修正,从而有效降低由于在入侵检测单纯使用聚类分析所导致的误报。详细阐述了改进的具体实现方案,并通过实验验证了该技术的可行性。This paper analyses the existing problems of the current intrusion detection techniques base on K-Means Algorithm: failing to analyse the attribute composed by character,higher false-detection rate,etc,and brings forward some improvement: We use Association Rule into clustering analysis to reduce the false-detection rate in our algorithm.In this paper,we introduce the improved method concretely,and shows the feasibility and effect through an experiment.福建省自然科学基金项目(2008F50602);福建省自然科学基金-青年人才项目(2008F3101

Surface-enhanced Raman Spectroscopy and Plasmon-Assisted Photocatalysis of p-Aminothiophenol

对氨基苯硫酚(PATP)是表面增强拉曼光谱(SErS)研究中最重要的探针分子之一.PATP吸附体系具有非常特征且异常强的SErS信号,但人们对其SErS信号的理解仍存在较大争议.本文结合文献,总结了我们为了理解PATP分子异常的SErS光谱所开展的系统的理论和实验工作.首先介绍PATP的SErS增强机理方面开展的理论工作,研究表明PATP分子的异常SErS信号不是来自PATP分子本身,而是来自其表面催化偶联反应产物二巯基偶氮苯(dMAb).通过实验和dMAb合成两个方面,验证了dMAb是异常SErS信号的根源.其次总结了各种实验条件对PATP转化为dMAb的影响,并从实验和理论两个角度探讨PATP的表面催化偶联反应机理.最后,通过对PATP体系的SErS和等离激元增强化学反应的总结,展望表面等离激元增强化学反应的未来发展方向.p-Aminothiophenol(PATP) is one of the most important probe molecules in surface-enhanced Raman spectroscopy(SERS).Adsorbed PATP exhibits very unique and abnormally intense SERS signals.However, the understanding toward the abnormal SERS signals is still in debate.In this review, we overview our theoretical and experimental studies to understand the abnormal SERS of PATP.We first introduce the theoretical investigation on the SERS enhancement mechanism of PATP.The theoretical study shows that the abnormal SERS signals of PATP are not from PATP itself but arise from its surface catalytic coupling product p,p'-dimercaptoazobenzene(DMAB).The assumption is supported by carefully designed experiments of PATP and the SERS signal of the synthesized DMAB molecule.Then, we summarize the experimental factors that influence the photochemical conversion of PATP to DMAB on the surfaces of metal nanostructures.We then explore the reaction mechanisms for the surface catalytic coupling reaction of PATP in both experimental and theoretical aspects.Finally, we proposed the further direction of surface plasmon enhanced chemical reaction on the basis of our systematically studies of SERS and plasmon photocatalysis of PATP

Activities of several digestive enzymes of Babylonia areolata Link (Gastropoda:Buccinidae)during early development

将方斑东风螺Babylonia areolata(Link)的早期发育从早期面盘幼体到变态后15d的稚贝分成6个阶段,分别测定各阶段蛋白酶(P)、脂肪酶(L)、淀粉酶(A)和纤维素酶(C)活性。研究结果表明,随着幼体发育的推进,蛋白酶比活力逐渐减小,脂肪酶比活力逐渐增加,淀粉酶和纤维素酶比活力则在变态前逐渐增加,而变态后逐渐减小。比较A/P和(A+C)/(P+L)两种指标指示方斑东风螺幼体发育过程中的食性变化,提出(A+C)/(P+L)用于指示方斑东风螺食性变化更合理、准确。综合比较幼体发育各阶段4种消化酶活性,发现在面盘幼体向稚贝变态期间,幼体消化能力最弱,原因与幼体的变态过程有关。实验结果也验证了贝类具有分泌纤维素酶的能力,该酶在东风螺对纤维素分解中占主导地位。Specific activities of protease(P),lipase(L),amylase(A) and cellulase(C) of Babylonia areolata Link were measured respectively at 6 different stages from early veliger to juvenile 15 days after metamorphosis.The activity of protease was found to decrease gradually over time,while the activity of lipase was detected to increase step by step with larval development.The activities of amylase and cellulase increased slowly within 12 days after hatch,then increased rapidly at competent larva stage and decreased sharply after metamorphosis.A comparison was made between two indexes used as indicators of feeding habit: ratio of amylase activity to protease activity(A/P) and ratio of the sum of amylase and cellulase to the sum of protease and lipase((A+C)/(P+L)).It was concluded that the latter index((A+C)/(P+L)) was more suitable than the former one(A/P) when they were used as indicators of feeding habit.The digestion pattern of Babylonia areolata Link was revealed with the summation of 4 kinds of digestive enzyme activities at the same stage.The digestion of juvenile 3 days after metamorphosis was the weakest among the 6 stages after comparing the summations at different stages.Weak digestion may be one of the most important reasons that influence the survival rate during metamorphosis.The results of specific cellulase activity at the 6 stages indicated that the Gastropoda were able to secrete cellulase themselves.Endogenous cellulase played a vital role for Babylonia areolata to digest cellulose.科技部农业科技成果转化基金项目(03EFN213500133

Vibrational Spectroscopy Criteria to Determine α-Pyridyl Adsorbed on Transition Metal Surfaces

Corresponding author. Email: [email protected]; Tel: +86-592-2189023[中文摘要]基于簇模型采用密度泛函理论在B3LYP/6-311+G**/LANL2DZ(metal)基组水平上计算了吡啶及α-吡啶基吸附于Pt、Pd、Rh、Ni四种金属表面的红外和拉曼光谱.通过详细地分析和比较计算结果与文献报道的实验谱图,提出了以N端吸附的吡啶分子和α-吡啶基这两种表面物种各自存在的谱学判据.计算结果表明在以上四种金属表面,α-吡啶基的拉曼活性比吡啶的小,而特征谱峰的红外强度与吡啶相当.该结果表明红外光谱是检测金属表面α-吡啶基的有效手段,也解释了采用表面增强拉曼光谱和红外光谱研究吡啶吸附在金属表面得出不同结构的原因.[英文摘要]Density functional theory calculations at the B3LYP/6-311+G**/LANL2DZ(metal) level were used to predict the infrared (IR) and Raman spectra for pyridine and α-pyridyl upon interaction with platinum (Pt), palladium (Pd), rhodium (Rh), and nickel (Ni) clusters. After carefully comparing the simulated IR and Raman spectra with the corresponding experimental spectra from literature, the characteristic frequencies for the metal surface adsorbed pyridine and α-pyridyl were determined. Our results show that on these metal surfaces α-pyridyl has a far lower Raman activity compared with pyridine, but their characteristic frequencies have comparable IR intensities. This is the reason why different adsorption configurations are proposed for the IR and the surface-enhanced Raman spectra (SERS). Our results indicate that IR spectroscopy is an effective tool to detect α-pyridyl adsorbed on metal surface.国家自然科学基金(20973143,91027009);国家重点基础研究发展规划(973)(2007CB815303,2009CB930703); 厦门大学(2010121020);国家科学人才培养基金(J1030415)资助项

An Anomaly Detection Method Based on Birch Algorithm

文章针对KNN存在的复杂度过高的问题,提出应用把BIRCH算法的层次聚类思想近似地计算weight的BirchOut算法,以降低其复杂度,同时利用孤立点挖掘的思想做异常检测.通过在KDD99数据集上的实验,我们验证了算法的有效性.A new algorithm called BirchOut is proposed to reduce the complexity of KNN calculation,which uses the idea of hiberarchy clustering,presents an anomaly detection method by using an outlier detection method.We apply this technique on KDD99 data set and get satisfactory results.福建省自然基金(2008F50602);; 福建省省青年人才项目(2008F3101

On the persistence of lower-dimensional invariant hyperbolic tori for smooth Hamiltonian systems

In this paper, sufficiently smooth Hamiltonian systems with perturbations are considered. By combining a smooth version of the Kolmogorov-Arnold-Moser theorem and the theory of normally hyperbolic invariant manifolds, we show that under the conditions of nonresonance and nondegeneracy, most hyperbolic invariant tori and their stable and unstable manifolds survive smoothly under sufficiently smooth autonomous perturbation. This result can be generalized directly to the case of time-dependent quasi-periodic perturbations. Finally, an example from geometrical optics is used to illustrate our method