当代大学生青年志愿者工作之现状调查分析

本文通过对厦门某高校1000多名大学生的问卷调查,调研了大学生对青年志愿者行动的认识、理解及心态等,为社会、高校研究大学生志愿服务情况并制定相关政策法规,及为志愿者活动创造良好的环境提供资料及合理化建议

低浓度甲醇完全氧化钙钛矿型La_(1-x)Sr_xMnO_3催化剂研究

采用溶胶－凝胶法制备钙钛矿型复合氧化物Ｌａ１－ｘＳｒｘＭｎＯ３，研究其对低浓度甲醇完全氧化催化性能．实验结果表明：Ｓｒ２＋取代量和样品焙烧温度对催化剂活性均有显著影响，以８７３Ｋ焙烧的Ｌａ０．６Ｓｒ０．４ＭｎＯ３的催化活性为佳；催化剂的ＢＥＴ，ＸＰＳ，Ｏ２－ＴＰＤ，Ｈ２－ＴＰＲ表征研究结果证实，较大的比表面，较高的表面Ｍｎ浓度和氧吸附量都有利于催化剂活性的提高

Multi-pattern Matching Technology Based on CUDA

文章以经典的多模式匹配算法—AC算法为例,通过对CudA特性的分析,提出了基于CudA的并行模型,设计了适合CudA并行技术的AC匹配算法。实验结果表明,基于CudA的AC匹配算法较CPu上获得了22倍的加速比,有效提高了入侵检测系统的性能。By analyzing the characteristic of CUDA, a parallel module of AC matching algorithm based on CUDA is proposed.Experiment shows that the AC multi-pattern matching algorithm based on GPU gets 22 times speedup ratio than it based on CPU, and it improves the performance of intrusion detection system effectively

某工程桩基质量问题的一种处理方法

据统计,国内灌注桩施工中桩身出现质量缺陷的概率达20%。一旦发生桩基质量事故,应及时进行事故原因分析评判,对事故进行处理,以保证建筑物的正常使用,并尽量减少经济损失。通过对一起桩基事故的分析和处理,说明其处理的方法及其原理,为今后相关处理提供经验借鉴

Simulation of surface topography considering process-machine interaction in grinding

磨削加工方法是保证加工表面质量的重要手段,机床结构与磨削过程之间存在的交互作用会对工件表面质量产生不利影响。以砂轮端面磨削加工过程为研究对象,在研究磨削工件表面形貌仿真方法的基础上,深入分析了机床结构与磨削过程之间交互作用对工件表面形貌的影响。首先基于砂轮表层磨粒的随机分布特性建立了虚拟砂轮形貌,然后通过对磨削过程中砂轮磨粒与工件几何干涉作用的分析,建立了磨粒运动轨迹方程和工件表面形貌方程。考虑砂轮变形对磨削过程的反向作用,建立了主轴-砂轮结构与磨削过程间的交互模型,采用耦合仿真的方法对机床-磨削交互过程进行了仿真,并考虑磨削过程中的交互作用提出了一种新的磨削工件表面形貌仿真模型,实验结果验证了所给算法的正确性和有效性,该方法为进一步优化磨削工艺参数提供了依据。Grinding is an important means to guarantee the quality of the machined surface,however,the interaction between machine and grinding process reduces surface quality. Focusing on face grinding,the influence of process-machine interaction on ground surface was analyzed based on the investigation of surface topography simulation. A visual wheel topology was simulated based on the random nature of grains located on the wheel surface. The grain trajectory equation and workpiece topography equation were established based on the analyses of interference between grains and workpiece. The interaction between grinding process and spindle-wheel was modeled considering the inverse influence of wheel deformation on process and simulated by adopting a coupling simulation method. Taking the processmachine interaction into account,a novel simulation model for surface topography of the grinding process was proposed.Grinding test verifies the accuracy and effectiveness of the given algorithm. The method can be further used to optimize the grinding process parameters.福建省高校产学合作科技重大项目“高效、高精度可转位刀片周边刃磨关键技术研究”(2014H6025

Microbial Study of Mangrove Soil at Dongzhai Harbor in Hainan.

Three groups of microbial amount of mangrove soil at Dongzhai harbor in Hainan were studied.The results show as follows:①Mean amount of soil bacteria in Kandelia candel forest and Bruguiera sexangula forest is 4 87×10 7 and 7 55×10 7〔ind·(g.dry soil) -1 〕 respectively,which is higher than that of controlled mudflat without mangrove forest〔1 22×10 7ind·(g.dry soil) -1 〕;②The amount of bacteria at layer of 10-20cm is the most in three layers of 0-10、10-20 and 20-30cm;③Mean amount of soil bacteria in Bruguiera sexangula forest is higher than that in Kandelia candel forest;④The amount of bacteria is related to the amount and distribution of plant residue and litter;⑤Filamentous fungi and actinomyces are not found out by normal isolation methods,which is perhaps related to least amount and special habitat of local mangrove soil.国家教委高校湿地研究中心专项经费资助项

Design of Electrical Downtilt Broadband Patch Antenna

针对室内壁挂基站应用要求,采用对称角形缝隙加载正方形贴片,实现具有电下倾辐射特性的低剖面宽带贴片天线结构。实验结果表明,设计天线S11参数小于-10db的相对阻抗带宽为5.15%。在工作频带内,天线辐射场可产生约30°的下倾角。并且可通过馈电位置的改变,实现辐射场下倾角的调整。水平平面辐射方向图表明,在120°范围内,其垂直极化辐射场要比水平极化高10db以上,表明天线具有良好的垂直线极化特性。工作频带内天线的增益约为6dbI。该天线可内置于壁挂基站以减小设备尺寸。To meet the requirements of electrical downtilt beam patterns and broad bandwidth for the indoor wallmounted base-station antennas,a symmetrically right-angled slot is loaded into the low-profile square patch antenna.The experimental results show that the relative impedance bandwidth with the parameter S11less than-10dB is 5.15% for the designed antenna.Over the operating frequency band,the electrical downtilt of radiation beams is about 30°.Meanwhile the downtilt can be adjusted by changing the feed position.In the angle range 120° of the horizontal plane pattern,the radiation level of the vertically polarized electric field is 10dB higher than the horizontal polarization,which indicates that the antenna has the radiation characteristics of vertically linear polarization.Over the working band the antenna gain is about 6dBi.The presented antenna can be built into the wall-mounted base station to reduce the device size.福建省重大科技专项(2010HZ0004-1

Ag修饰La_(0.6)Sr_(0.4)MnO_3基催化剂氧物种的谱学表征

采用柠檬酸溶胶-凝胶法制备钙钛矿型La0.6Sr0.4MnO3 氧化物, 并用Ag 对其进行修饰,制得Ag/La0.6Sr0.4MnO3 催化剂.活性评价结果显示, Ag 的修饰能显著提高原基质催化剂La0.6Sr0.4MnO3 对低浓度CH3OH和CO完全氧化的催化活性, 相应于95% CH3OH和CO转化所需反应温度T95分别可低至421 和370 K. 催化剂的XPS和LRS谱学表征结果揭示, 在6% Ag/La0.6Sr0.4MnO3上, 具高度反应活性的表面氧物种O22- (a)和O-(a)在总表面氧中所占克分子百分数(m ol% )几近未经Ag 修饰的基质体系La0.6Sr0.4MnO3 的两倍. O2-TPD测试结果证实,Ag 对La0.6Sr0.4MnO3基质的修饰、掺杂和部分取代使其对O2 的低温吸附能力大为提高,诱生出一类数量可观具有低温吸-脱附性能的吸附氧物种. 本文结果表明, Ag/La0.6Sr0.4MnO3 催化剂对CH3OH和CO完全氧化高的催化活性与Ag 的修饰提高了催化剂对氧的低温吸附活化能力, 并使催化剂上对CHX, CH3OH, HCHO和CO具高度反应活性的表面氧物种O22- (a)和O-(a)的相对含量明显增加密切相关

低浓度甲烷甲醇深度氧化Ag/La_(0.6)Sr_(0.4)MnO_3催化剂

用柠檬酸溶胶 凝胶法制备钙钛矿型La0.6Sr0.4MnO3 氧化物,并用Ag对其进行修饰,制得Ag/La0.6Sr0.4MnO3 系列催化剂.结果表明 ,6 %Ag/La0.6Sr0.4MnO3 催化剂上甲烷或甲醇氧化转化95 %时的反应温度T95 可低至735K(对CH4)或421K(对CH3OH);适量Ag的负载修饰并不改变催化剂基质氧化物La0.6Sr0.4MnO3 的纳米级钙钛矿型结构;Ag的掺杂诱使催化剂中部分Mn3 +氧化为Mn4 +;Ag组分与钙钛矿型氧化物基质La0.6Sr0.4MnO3 表面的相互作用促使该催化剂对甲烷或甲醇的完全氧化表现出高而稳定的催化活

煤制合成天然气用甲烷化催化剂的研发进展

本文概述近10年来国内外在煤制合成天然气用甲烷化催化剂的研发动态,并报道本研究组在高效新型Ni-ZrO2基催化剂的研发进展