正交匹配追踪和BIC准则的自适应双频段预失真模型优化算法

针对双频段预失真模型复杂度高以及当前的模型优化算法不具有自适应性的问题,提出一种自适应的模型优化算法.采用双频段广义记忆多项式作为预失真模型,通过正交匹配追踪算法对原始模型的基函数项进行排序,每次迭代时用所有已挑选的基函数项构成备选模型,推导了模型输出向量元素服从非独立同分布情况下的贝叶斯信息准则(Bayesian Information Criterion,BIC),并将BIC值最小的备选模型作为优化后模型,从而在原始模型稀疏度和拟合误差门限未知情况下,实现了模型的自适应优化.结果表明:优化后模型与原始模型相比,二者分别预失真后的信号在邻道功率比和归一化均方误差方面均非常接近,预失真效果良好,而模型的系数量减少了75%以上.国家自然科学基金项目(No.61401099);;福建省教育厅项目(No.JAT170087

Performance of FM-DCSK UWB for wireless body area network

超宽带(ulTrA WIdE bAnd,uWb)技术具有低功耗、抗多径能力强等特点,已被无线体域网(WIrElESS bOdy ArEAnETWOrk,WbAn)作为一种候选传输技术,而调频差分混沌位移键控超宽带(frEQuEnCy-MOdulATEd dIffErEnTIAl CHAOSSHIfT kEyIng ulTrA WIdEbAnd,fM-dCSk uWb)实现简单,在接收机端不需要信道估计、信道均衡和rAkE接收,也得到了广泛的研究。主要对fM-dCSk uWb技术在WbAn的体内到体表、体表到体表和体表到体外3种信道模式下的性能进行了计算机仿真,并对影响其系统性能的积分时间和保护间隔2个参数进行了分析,仿真结果表明,fM-dC-Sk uWb技术用于WbAn信息传输是可行的。Ultra wideband(UWB) technique is adopted by the wireless body area networks(WBAN) as one of the most promising candidates due to its low power spectral density and high robustness against multipath fading.FM-DCSK UWB has gained much attention for its merits of no requiring channel estimation,channel equalization and rake reception in the receiver side.In this paper,the feasibility of FM-DCSK UWB over different WBAN channels,including implant to body surface,body surface to body surface and body surface to external,is investigated.Two system parameters directly affecting the system performance,i.e.,integration interval and guard interval,are carefully investigated respectively.Simulation results show that FM-DCSK UWB can be used as a feasible transmission technology for WBAN.国家自然科学基金(61001073;60972053)~

Des ign for Communication of Data Center of GPRS DTU

中文摘要：介绍了基于 GPRS 网络的电力监控系统结构, 并根据 GPRS DTU 的特点, 结合网络编程的知识, 在 VC++6.0 平台上实现了 GPRS DTU 的数据中心的通信功能。英文摘要：This paper introduces the power monitoring and controling sys tem architecture,which is bas ed on GPRS,and according to the traits of GPRS DTU,combining the knowledge of network programming.This paper implements the functions of com- munication on data centers of GPRS DTUs on the platform of VC++6.0

Research on coexistence between CS-DCSK UWB and narrow-band communication systems

分析了密集多径环境下码复用差分混沌移位键控(COdE-SHIfTEd dIffErEnTIAl CHAOS SHIfT kEyIng,CS-dCSk)超宽带(ulTrA WIdEbAnd,uWb)通信系统在单个和多个窄带干扰(nArrOW bAnd InTErfErEnCE,nbI)信号下的比特误码率(bITErrOr rATE,bEr)性能。建立CS-dCSk uWb系统仿真模型,并通过采样扩展方法推导出bEr的表达式,从而得到系统在不同干扰条件下的bEr性能。分析和仿真结果表明,nbI信号对系统有明显干扰作用,但系统性能在不同频率干扰下保持稳定。The performance of code-shifted differential chaos shift keying(CS-DCSK) ultra wideband(UWB) communication system under single or multiple narrow band interferers is analyzed in dense multipath environments.The bit error rate(BER) is derived on the basis of the sampling expansion approach under different interference strengths.The simulations and analyses demonstrate that the NBI signal interferes significantly the performance of system.However,the system performance keeps stable under interferer with different frequencies.国家自然科学基金(61001073;60972053); 欧盟FP7(294923)~

SoPC application system design based on the linux

中文摘要: 利用 XILINX 公司的 EDK 软件搭建一个基于 PowerPC 的片上系统, 并且在定制的 SoPC 系 统上移植 Linux 系统, 最后利用此系统完成了一个具体的嵌入式应用系统设计。实验表明, 这种基于 Linux 的 SoPC 应用系统设计, 很好地结合了 SoPC 和 Linux 系统的优点,用户可以根据需要灵活地定制 出软硬件平台, 满足复杂多变的嵌入式需求, 加速产品的开发。英文摘要：A SoC system based on PowerPC is build up by using EDK software of Xilinx, then Linux system is porting to this system. At last , a specific embedded application system is implemented on this system. Experiment shows that this SoPC system with both the advantage of SoPC and Linux system is able to meet various demands for embedded application and accelerate the development of product by building up software and hardware platform freely according to customer’s demands

Key Technology for Improving Resistance Against Chloride Ion Penetration of Marine Concrete

为了提高海工混凝土的抗氯离子渗透性,从原材料选择与配合比优化设计方面探讨了提高海工混凝土抗氯离子渗透性的关键技术,并对福建厦门杏林湾九天湖大桥工程案例进行了分析。结果表明,将Ⅱ级粉煤灰、矿粉和混凝土抗氯离子增强剂按一定比例复配,对混凝土配合比进行优化设计,能够有效提高海工混凝土的抗氯离子渗透性。In order to improve resistance against chloride ion penetration of marine concrete,the key technology for improving resistance against chloride ion penetration of marine concrete was discussed from the choice of raw materials and the mixture proportion design,and the engineering example of Xiamen Xinglin Bay Jiutianhu Bridge of Fujian Province was analyzed.The results show that confecting Ⅱ fly ash,slag powder and concrete strengthening agent on resistance against chloride ion penetration in a certain proportion and optimizing the mixture proportion design of concrete,can effectively improve the resistance against chloride ion penetration of marine concrete.国家自然科学基金重大国际合作研究项目(2005CCA06700);福建省建设厅科技计划项目(2005-2-2

苏云金芽胞杆菌(Bacillus thuringiensis)几丁质酶的分离纯化及酶学性质

以苏云金芽胞杆菌为材料 ,通过硫酸铵沉淀分级分离、DEAE - 32离子交换柱层析初步纯化 ,获得比活力为15 0 .5Umg-1的酶制剂 .研究酶催化胶体几丁质水解的反应时间和酶量对酶活力的关系 ,探讨酶催化胶体几丁质的最适条件 .温度和 pH对酶活力的影响和酶的热稳定性及酸碱稳定性的结果表明 :酶催化胶体几丁质水解的的最适pH为 5 .6、最适温度为 5 8℃ .该酶在pH 4 .5～ 6 .5区域稳定 ,而在pH >8能很快失活 ;在 5 5℃以下处理 30min ,酶活力保持不变 ;高于 5 5℃ ,酶快速失活 .图 5参 1

有机溶剂对苏云金芽孢杆菌(Bacillus thuringiensis)几丁质酶的影响

　以苏云金芽孢杆菌(Bt)的发酵液为材料,经硫酸铵分级分离、DEAE-32离子交换柱层析分离,获得部分纯化的Bt几丁质酶(EC3. 2. 1. 14)制剂.研究了几种有机溶剂对Bt几丁质酶的影响.结果表明,甲醇、丙三醇、甲醛和戊二醛对几丁质酶有抑制作用;乙醇、丙醇、乙二醇和二甲亚砜在低浓度时对酶有激活作用,随着浓度的升高表现出抑制作用;二氧六环的浓度低于 5%时,对酶的影响不明显,而高于 5%时,对酶则有激活作用;丙酮对酶有激活作用. 图 1参 1

盘状软骨的关节镜下治疗及临床特点

目的　总结盘状软骨的关节镜下治疗的方法和疗效及临床特点 ,为日后更好的诊治盘状半月板提供依据。方法　 31例(31膝 )盘状软骨患者分别采用关节镜下成形术 2 7例和全切术 3例、 1例边缘撕裂成形后缝合修补术。结果　按Ikeuchi氏膝关节评价等级评定疗效 :优 17例 (5 4 8%) ,良 11例 (35 5 %) ,可 3例 (9 7%)。 3例术后自述有弹响 ,查体见其中 2例有外侧半月残留部不稳的体征。结论　盘状软骨在膝关节屈伸运动中所产生的非生理性运动 ,易造成盘状软骨的破裂、关节软骨磨损以至关节软骨早期出现退行性改变等 ,症状性盘状软骨一旦发现 ,无论破裂与否均应早期手术。关节镜下盘状软骨成形术可获得优良疗效。盘状软骨引发的弹响交锁有其特征性临床特点 ;MRI对盘状软骨诊断有确诊意义

Electrocatalytic Activity of Palladium Nanocatalysts Supported on Carbon Nanoparticles in Formic Acid Oxidation

采用化学还原法制备了碳纳米粒子支撑的钯纳米结构(Pd-CNP). 透射电镜表征显示在Pd-CNP纳米复合物中，金属Pd呈菜花状结构，粒径约20~30 nm。它们由许多更小的Pd纳米粒子（3~8 nm）组成. 电化学研究表明，虽然Pd-CNP的电化学活性面积比商业Pd黑低40%（可能原因是部分Pd表面被一层碳纳米粒子覆盖），但其对甲酸氧化却表现出更好的电催化活性：质量比活性和面积比活性都比Pd黑高几倍. 催化活性增强的原因可能是碳纳米粒子支撑的Pd纳米结构具有特殊的层次化结构，可以形成更多的活性位，以及表面位更利于反应进行.Palladium nanostructures were deposited onto carbon nanoparticle surface by a chemical reduction method. Transmission electron microscopic studies showed that whereas the resulting metal-carbon (Pd-CNP) nanocomposites exhibited a diameter of 20 to 30 nm, the metal components actually showed a cauliflower-like surface morphology that consisted of numerous smaller Pd nanoparticles (3 to 8 nm). Electrochemical studies showed that the effective surface area of the Pd-CNP nanoparticles was about 40% less than that of Pd black, possibly because the Pd nanoparticles were coated with a layer of carbon nanoparticles; yet, the Pd-CNP nanocomposites exhibited marked enhancement of the electrocatalytic activity in formic acid oxidation, as compared to that of Pd black. In fact, the mass- and surface-specific activities of the former were about three times higher than those of the latter. This improvement was likely a result of the enhanced accessibility of the Pd catalyst surface and the formation of abundant active sites of Pd on the carbon nanoparticle surface due to the hierarchical structure of the metal nanocatalysts.This work was supported, in part, by the National Science Foundation (CHE–1012256 and DMR–0804049) and by the ACS-Petroleum Research Fund (49137–ND10). J. H. was supported, in part, by a research fellowship from the China Scholarship Council. TEM work was performed as a User Project at the National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, which is supported by the US Department of EnergyThis work was supported, in part, by the National Science Foundation (CHE–1012256 and DMR–0804049) and by the ACS-Petroleum Research Fund (49137–ND10). J. H. was supported, in part, by a research fellowship from the China Scholarship Council. TEM work was performed as a User Project at the National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, which is supported by the US Department of Energy作者联系地址：1. 加利福尼亚大学化学与生物化学系，美国 圣克鲁兹 95064; 2. 西北工业大学凝固技术国家重点实验室，陕西 西安710072Author's Address: 1. Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States; 2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China通讯作者E-mail：[email protected]