广州市园林绿地树木健康调查与评价

采用随机样方法,调查了广州市3类城市绿地中的1 483株园林树木的健康状况,结果显示大部分的园林树木生长较健康,园林树木生长存在的主要问题是枝叶病、虫害等。3类绿地5类亚型中,园林树木健康高低次序是:公园人工植被>路侧绿带>行道树绿带>公园自然植被>校园绿地。园林树木健康与植物多样性指标的相关分析结果显示,城市绿地中的园林树木的生长状况与植物多样性有一定的联系。根据调查的结果,对城市绿地的园林树木管养和配置提出了建议。     

Co-occurrence of Dominant Direct and Indirect Transitions in Low Temperature Sputtered Indium Tin Oxide Thin Films on Polymers

Indium tin oxide （ITO） layers are prepared on polymethylmethacrylate and polyethylene terephthalate by rf- magnetron sputtering at room temperature. Their 3D-AFM images and visible transmittance spectra are contrastively characterized and studied. An interesting morphological effect of the polymer substrates on their top ITO layers is observed. Dominant direct and indirect transition types deduced from optical spectra are surprisingly found in ITO films on different polymers. Furthermore, qualitative band structures are figured, and some theoretical discussions about the correlation of optical band structure, interface/surface morphology and carrier density are also presented.     

急件订单干扰下虚拟单元重调度

虚拟单元生产中,针对急件订单干扰情况,研究了考虑序位相似性,即尽量保持初始工序的加工次序的虚拟单元重调度问题。为了应对急件订单干扰,设置了各工件工序可用机器集合和相应的加工时间集合,构建了以序位相似性最大和急件订单完工时间、系统总流程时间最短为目标的多目标非线性整数规划模型。针对模型自身特征,采用了遗传—蚁群算法相结合的优化算法求解模型。最后,以船舶实际生产为例,验证了模型的可行和优越性,以及算法的有效性。     

波长色散X射线荧光光谱法测定长石主次量组分

采用高温熔融制样,X射线荧光光谱法同时测定长石中的SiO2、Al2O3、CaO、MgO、Na2O、K2O、Fe2O3、TiO2、Cr2O3等主次量元素.通过选用长石、叶腊石、高岭土及土壤等标准样品,并在标样中引入分析纯TiO2、Cr2O3,解决了长石成分分析标准样品不足的问题.采用理论α系数和经验系数校正法克服了谱线重叠干扰和基体效应影响.测定长石各组分的相对标准偏差(RSD,n=10)均小于5％,方法检出限为1.21-97.33μg/g,测定值与化学分析法结果吻合.     

金锡共晶互连对HP-LED光热性能的改善

随着功率型LED(HP-LED)对散热的要求越来越高,传统导电银胶越来越难以满足LED的高散热要求。虽然共晶互连工艺是微电子领域中的一种有效的散热互连方法,但是由于LED的特殊性,该工艺在LED互连封装中的性能改善研究还比较少。本文对金锡共晶互连、锡膏互连和银胶互连的3种LED器件分别进行了光学、热学以及剪切力等方面的测试分析研究,结果表明:底部与顶部同时加热的金锡共晶工艺互连的LED器件可以有效地改善仅底部加热共晶互连层中的空洞缺陷,在1 000 mA电流条件下,相对于锡膏、银胶互连的LED器件具有较低的热阻、较稳定的峰值波长偏移、较强的互连层剪切力等性能。金锡共晶互连工艺是一种可以有效改善大功率LED散热及互连强度的方法。     

Traveling Waves for Nonlocal and Non-monotone Delayed Reaction-difusion Equations

We study the existence of traveling wave solutions for a nonlocal and non-monotone delayed reaction-difusion equation.Based on the construction of two associated auxiliary reaction difusion equations with monotonicity and by using the traveling wavefronts of the auxiliary equations,the existence of the positive traveling wave solutions for c≥c is obtained.Also,the exponential asymptotic behavior in the negative infnity was established.Moreover,we apply our results to some reactiondifusion equations with spatio-temporal delay to obtain the existence of traveling waves.These results cover,complement and/or improve some existing ones in the literature.     

个离散造血模型概周期解的吸引性和振动性(英文)

By using a new fixed point theorem, sufficientconditions are obtained for the existence of a positivealmost-periodic solution for an discrete model of hematopoiesis with almost-periodic coefficients. Its attractivity and oscillation are investigated.     

变时滞Hopfield神经网络的全局指数稳定性

本文研究了一类具有变时滞Hopfield神经网络的稳定性问题.利用时滞微分不等式方法,获得了几个关于该网络的全局指数稳定性与时滞无关的充分条件,并且给出了此类网络的收敛指数的估计,推广了已知文献的结果.最后给出数值例子证明结论的有效性.     

"我"——"三草酸合铁(Ⅲ)酸钾晶体"的生长及影响因素

This article tries to personify potassium ferrioxalate crystal as "I" to describe the formation process and the factors affecting the growth of potassium ferrioxalate crystal. After growing into beautiful green crystals, I dreamed I was participating in the jewelry beauty contest. A serious of wonderful conversations between emerald and I revealed the properties and applications of potassium ferrioxalate crystal. It inspires and guides students to understand the growth of crystals and their properties, and it also stimulates students' interest in studying chemistry.     

Influence of Dopants in ZnO Films on Defects

The influence of dopants in ZnO films on defects is investigated by slow positron annihilation technique. The results show S that parameters meet S_Al>S_un>S_Ag for Al-doped ZnO films, undoped and Ag-doped ZnO films. Zinc vacancies are found in all ZnO films with different dopants. According to S parameter and the same defect type, it can be induced that the zinc vacancy concentration is the highest in the Al-doped ZnO film, and it is the least in the Ag-doped ZnO film. When Al atoms are doped in the ZnO films grown on silicon substrates, Zn vacancies increase as compared to the undoped and Ag-doped ZnO films. The dopant concentration could determine the position of Fermi level in materials, while defect formation energy of zinc vacancy strongly depends on the position of Fermi level, so its concentration varies with dopant element and dopant concentration.