Design of Carrier Synchronization Based on Costas Loop

介绍了平方变换法相干解调原理,从工程角度完善了载波提取的电路结构,消除了频移载波的误锁问题.提出用科斯塔斯环法来实现从2dPSk信号中提取相干载波,解决了提取的载波信号存在180度的相位含糊问题,为通信系统提高抗噪性能提供了条件.当载波频率很高时,工作频率较低的科斯塔斯环易于实现.并用SIMulInk设计出科斯塔斯环法提取载波的仿真电路图和进行相应的仿真实验.Theory of coherent demodulation based on method of square counterchange is introduced in this article.The structure of circuit for carrier recovery is perfected in engineering,and the problem of error-lock for frequency-shift carrier is eliminated.Costas Loop is put forward to achieve coherent carrier from 2DPSK signal in this article.The 180° phase's inexplicit problem which exist in carrier recovery is resolved.It improves the resisting noise property of communication system.When carrier frequency is higher,Costas loop is easy to implement carrier synchronization.Because the operating frequency of Costas loop is lower than square PLL.We scheme out emulational circuit diagram for carrier distilling with Costas loop by using simulink and process corresponding emulational experiment.国家自然科学基金项目(60873179);广西教育厅科研项目(200707LX196

Compressed Storage for C-Temporal Relation Data Model Based on Improved Genetic Algorithm

针对时态数据库中存在数据冗余、数据量快速增长等问题,结合现有压缩技术,提出基于改进遗传算法的C-TrdM压缩存储技术。将各个时刻的时态关系数据分解为最小粒度的数据并进行编码,采用改进的遗传算法来计算待压缩数据中的最优存储数据以提高压缩比。算法的快速收敛性使去除数据冗余的速度得到提高。There is data redundancy temporal database and the quantities of temporal database are increasing fleetly,aiming at these problems,this paper puts forward compressed storage tactics based on improved genetic algorithm for temporal data which combine compress technology in existence in order to settle data redundancy in the course of temporal data storage.Temporal relation data at any moment is decomposed into least granularity data and be coded meanwhile.Optimized storage data are figured out by using improved genetic algorithm,and the ratio of compression is enhanced.Celerity astringency of the algorithm can heighten speed of removing data redundancy largely.广西教育厅科研基金资助项目(200707LX196);广西工学院自然科学基金资助项目(院科自0704102

A quickly-speed running watermarking algorithm based on quantum evolutionary algorithm

针对传统基于人类视觉系统特性的空间域与变换域相结合的水印算法中嵌入信息量小、嵌入位置定位及检测准确率低和算法运行速度慢等缺陷,提出并实现一种基于量子进化算法(QEA)的快速水印新算法。仿真实验结果表明,新算法不仅生成水印图像的速度快,而且对各种攻击具有良好的敏感性和鲁棒性。新算法在应用中有较大的灵活性,并且具有可嵌入信息容量大、运算速度快和可操作性强等特点。There are limitations such as smaller embedded information capacity,lower accurate rate for positioning embedded location and detection and slower running speed in traditional watermarking algorithm which combines spatial domain and transform domain based on characteristics of human visual system.A quickly-speed running watermarking algorithm based on quantum evolutionary algorithm is proposed and implemented.The simulation results show that the proposed algorithm owns not only faster watermark image generation,but also have good sensitivity and robustness for all kinds of attacks.The proposed algorithm is more flexible in application,and it can embed more information and improve the computing speed.The method can be easily operated.国家自然科学基金资助项目(60873179);广西教育厅科研资助项目(200707LX196

High efficient and secure group key management scheme based on optimized GDH

针对gdH(grOuP dIffIE-HEllMAn)方案中节点可能成为系统的瓶颈以及计算复杂度、通信代价和存储复杂度远高于某些集中式方案等缺陷,提出并实现了一种基于优化gdH协商的高效安全的动态群组密钥管理方案,并对其安全性进行了证明。通过对计算量和通信量进行分析比较表明,优化gdH协商协议具有很大的优势,并且能够快速产生或更新组密钥,具有很强的实用性。There are some defects in GDH(group diffie-hellman) scheme,such as the node that may become the bottleneck of the system,and the computational complexity,cost of communications and storage complexity that are much higher than some centralized group key management program.An efficient and secure dynamic group key management scheme based on optimized GDH is proposed and implemented and its security is proven.The optimized GDH consensus agreement has great advantage than GDH by comparing and analysing the volume of calculating and traffic.At the same time,the optimized GDH consensus agreement can quickly produce and update group key,and it owns highly practicability.国家自然科学基金资助项目(60873179);广西教育厅科研资助项目(200707LX196

化学模拟生物固氮——Ⅸ 铁钼辅基模型化合物的合成和性能表征

本文曾在全国化学摸拟生物固氮协作组领导小组扩大会议(昆明,1980,8)上宣读。[中文文摘]采用乙二醇基阴离子作为活插头(可通过水解除去的双配位螯形配位体),对前文提出的合成方法作了重要改进,以期所合成的铁钼辅基模型化合物中Mo~(Ⅳ(Ⅲ))第一配位界内两个不稳定的配位体处于相邻的位置,如厦门模型Ⅲ(或厦门模型Ⅱ)所要求。合成和重组活性评价结果,重组活性比使用乙腈等为活插头的提高2个数量级,化学催化活性和选择性接近于天然FeMo-co水平。[英文文摘]A significant improvement has been made to the method previously proposed[3] for synthesizing FeMo-co modeling compounds. With the use of ethylene glycolate anion as labilizable blocking agent (hydrolyzable bidentatc chelating ligand)to protect two neighboring coordination sites in the first coordination sphere of MoIV(III) of the synthesized FeMo-co modeling compound, an increase in reconstituted-nitrogenase activity of 2 orders of magnitude of the sample synthesized (as compared with the use of acetoni-trile or other monodentare ligands as bloeking agents)has been obtained.Catalytic activity and selectivity assays as well as preliminary characterization by EPR method have also been made

Synthesis and Spectroscopic and Structural Characterization of Racemic Ammonium Dimeric(malato)dioxomolybdenum

联系人简介:周朝晖(1964年出生),男,教授,从事配位催化研究.E-mail:[email protected][中文文摘]钼酸铵和外消旋苹果酸溶液反应得到外消旋苹果酸钼(VI)配合物,(NH4)4[Mo∧O2(S,S-Hmal)2]·[MoΔO2(R,R-Hmal)2],对该配合物进行了元素分析、电导测定、旋光和红外光谱表征 ,并测定了晶体结构 .该化合物晶体属单斜晶系,P21/a空间群,晶胞参数:a=0.8061(2)nm,b=1.3286(2)nm,c=1.3232(2)nm,β=91.80(2)°,V=1 .4164(9)nm3,Z=2,Dc=2.008g·cm-3,F(0 00)=864,μ=9.70cm-1,一致性因子 R=0.051,Rw=0.0 58.在该单核配合物阴离子中,钼上的两个苹果酸配体具有相同手性,它以α-烷氧基和α-羧基双齿配位形成畸变的八面体构型,而另一个β-羧酸则保持自由状态。[英文文摘]The complex (NH4)4 [Mo∧O2(S,S-Hmal)2]·[MoΔO2(R,R-Hmal)2] was prepared from the reaction of ammonium molybdate and R,S-malic acid at pH= 2—3. It w as characterized by elementary analysis, conductivity measurement,optical rotation, IR and X-ray diffraction. The complex cry stallizes in monoclinic space group P21/a with unit cell parameters:a=0. 8061(2)nm,b=1.3286(2)nm,c=1.3232(2)nm, β= 91.82(2)°,V=1.4164(9)nm3,Z= 2, Dc= 2.008g ·cm-3,F(000)=864,μ=9.700cm-1 for 1902 reflections with I≥3%(I).The molybdenum atom is coordinated by two bidentate homochiral malic acid in distorted octahedron,w hile the β-carboxy l groups remain uncomplexed.The crystal contains two isolated monomeric malatomoly bdates(Ⅵ)anions in the configurat ions of ∧-S,S and Δ-R,R.The two enantiomeric anions result in the formation of racemic compound. There is no evidence for the other diastereoisomers like (NH4)2[Mo∧O2(R,S-Hmal)2],(NH4)2[MoΔ O2 (R,S-Hmal)2],(NH4)2[Mo∧O2(R,R-Hmal)2]and ( NH4 )2[MoΔO2(S,S-Hmal)2] in this experiment.国家自然科学基金(批准号:29933040);高等学校骨干教师资助计划;博士学科点基金资

Effects of seawater acidification and Cu~(2+) exposure on nutrient assimilation and energy allocation of Cladocopium goreaui

Recently, environmental stress due to global climate changes and human activities has exacerbated the occurrence of coral reef bleaching events. Ocean acidification and copper pollution have become the main stressors in reef areas. In this study, exposure experiments were performed at two pH levels (8.1 and 7.6) and two Cu~(2+) levels (4.25 and 16.47 mug/L) to explore the effects of seawater acidification and Cu~(2+) exposure on nutrient assimilation, energy consumption, and allocation of Cladocopium goreaui. Short-term seawater acidification exposure was found to increase the nutrient assimilation (carbohydrate and protein content) and decrease the energy consumption of C. goreaui, thereby increasing its energy allocation. Meanwhile, Cu~(2+) exposure significantly increased the energy consumption of C. goreaui, thereby reducing its energy allocation. Further, compared with the Cu~(2+) exposure alone, the combination of seawater acidification and Cu~(2+) exposure promoted the nutrient assimilation (increased carbohydrate and protein content) and energy allocation of C. goreaui. In general, these results show that seawater acidification and Cu~(2+) pollution in reef areas could negatively affect the nutritional metabolism and energy allocation of C. goreaui, possibly affecting its growth and reproduction in the future

Catalytic Mechanism of Nitrogen Reduction by Nitrogenase and its Chemical Modeling

作者简介:周朝晖,(1964-),男,教授;蔡启瑞(1914-), 男, 院士. 通讯联系人; e-mail: [email protected][中文文摘]固氮酶是某些微生物在常温常压下固氮成氨的主要催化剂 ,其催化机理和化学模拟是国际上长期致力研究的对象 .尽管人们已经揭示了固氮酶催化活性中心铁钼辅基 (Fe Mo- co) Mo Fe7S9(R-高柠檬酸 )的结构 ,然而 ,有关 Fe Mo- co生物合成的详细途径和其中包含的钼铁转移和利用 ;固氮酶在哪些活性位和按什么模式结合 N2 ,C2 H2 、CO等多种底物或抑制剂 ;以及其中涉及的电子和质子传递过程等许多问题 ,至今尚有待解决 .本文将综述这些问题的研究进展和厦门大学固氮组最近五年来的相关研究工作.[英文文摘]Nitrogenase catalyzes the reduction of dinitrogen to ammonia coupled to the hydrolysis of ATP, which is central to the process of biological nitrogen fixation. X-ray crystallographic structures has revealed its catalytic metal center FeMo-cofactor as a cage structure of MoFe7S9(R-homocitrate), in which the homocitrate coordinate bidentately to molybdenum. Recent efforts towards establishing the mechanism of activation of nitrogen around the metal center and the early biosynthesis process of FeMo-co are reviewed,which reflect a combination of structural,spectroscopic,synthetic, biochemical and theoretical approaches to this challenging problem pursued especially from the nitrogen fixation group of Xiamen University.国家自然科学基金(29933040);高等学校博士学科点基金;教育部骨干教师基金; 厦门大学科学研究基金资助项