铀的电子能量损失谱密度泛函理论计算及实验研究

采用密度泛函理论计算及实验获取了铀的电子能量损失谱（Electron energy loss spectroscopy,简称EELS）。计算的谱峰位置与实验一致。结合计算得到铀的能带及态密度对计算谱及实验谱特征峰进行分析,结果表明：由于铀的5f电子形成窄带对等离子体振荡贡献较小,6p电子的共振跃迁致使等离子振荡频率降低;实验谱中13．3eV能量损失峰为体等离子体振荡峰,20．3eV能量损失峰为6p能带到费米能级跃迁能量损失峰,27．6eV能量损失峰为两次体等离子振荡吸收峰。     

Analysis of the Variability of the L-H Transition Power Threshold in a Helium-4 Discharge

In this paper, a mechanism about the variability of the L-H transition power thresh- old PL-H is proposed which is based on the ion orbit losses. Only in the edge where there are enough ion orbit losses and the negative radial electric field Er is high enough can the H-mode be triggered. The ion orbit losses are determined by the ion in the loss region under certain edge conditions. For different mass A and different charge Z, the critical loss energy E Z2/A in the loss region. In H and D charges, because the D＋ loss region is larger than H＋, it can be deduced that the PL-H of H is larger than that of D. In a 4He discharge, experiment finds there exist a considerable number of 4He1＋ in the plasma edge. The actual ion orbit losses are determined by the mixing ratio of a He1＋ and 4He2＋. The 4He1＋ loss region is larger than that of 4He2＋, and the loss region of D＋ interposes between 4He1＋ and 4He2＋. Different 4He1＋ content can cause the edge ion losses in a 4He discharge to be greater than, less than or equal to that in a D discharge. So a 4He discharge can exhibit multiple experimental phenomena in the PL-H.     

侧向辐射的平面小天线的数值分析

在短距离移动通信中，由于系统对天线的效率和增益要求不高，人们大量使用FR4（玻璃纤维双面铜板）构造的天线，但未见损耗的分析报道。分析了一种构造于廉价的玻璃纤维电路板上的侧向辐射的小型平面天线，首次给出了天线在不同的介质损耗正切（tgδ）下的天线阻抗带宽，天线辐射效率以及方向图和天线增益的数值分析结果。     

动态力学及介电法研究蓖麻油丙烯酸酯共聚网络悬挂链的弛豫运动

用动态力学（内耗）和介电方法研究了由蓖麻油（ｃａｓｔｏｒｏｉｌ）、甲苯二异氰酸酯（ＴＤＩ）、丙烯酸羟乙酯（ＨＥＭＡ）组成的网络（Ａｉ）和由正己醇取代Ａ网络中部分ＨＥＭＡ组成的网络Ｂｉ（ｉ＝０，１，２，３）两种网络的内耗及介电损耗，内耗峰强度随悬挂链数目增加而升高，证实了网络破坏后形成的悬挂链的运动对内耗及介电损耗峰高有明显的贡献。     

同时存在横向位移和角度偏差时两平板光波导的连接损耗

用对称平板光波导基模场的高斯近似来计算同时存在横向位移、角度偏差以及波导参数不一样情况两单模平板波导的连接损耗，导出了非常简单的公式，同时也给出了数值计算的实例。     

Design of a 24-40 GHz balanced low noise amplifier using Lange couplers

A wide band(24-40 GHz)fully integrated balanced low noise amplifier(LNA)using Lange couplers was designed and fabricated with a 0.15/zm pseudomorphic HEMT(pHEMT)technology.A new method to design a low-loss and high-coupling Lange coupler for wide band application in microwave frequency was also presented.This Lange coupler has a minimum loss of 0.09 dB and a maximum loss of 0.2 dB over the bandwidth from 20 to 45 GHz.The measured results show that the realized four-stage balanced LNA using this Lange coupler exhibites a noise figure(NF)of less than 2.7 dB and the maximum gain of 30 dB;moreover,a noticeably improved reflection performance is achieved.The input VSWR and the output VSWR are respectively less than 1.45 and 1.35 dB across the 24-40 GHz frequency range.     

基于质量损失函数的仪器最佳校准周期的确定

根据现行标准,测量器具的校准周期由各生产厂家和研究机构根据具体情况自行规定.田口(Taguchi)质量工程学给出了单质量特性情况下的最佳校准周期确定方法,但没有多质量特性下的计算公式.文中从质量经济性出发,使用马氏距离度量多元测量质量特性,应用田口二次质量损失函数,以数字信号源为例推导其最佳测量周期的理论公式,为该仪器测量周期的确定提供了理论依据.     

Soil and leaf nutrient interactions following application of calcium silicate slag to sugarcane

In certain areas of the Everglades Agricultural Area, plant and ratoon sugarcane (Saccharum L.) yields are increased by application of Si from calcium silicate slag. The greatest yield responses are obtained in the plant crop the first year after application of slag and when plant uptake of Si is increased. Magnesium deficiencies have been reported after slag application. The objective of this study was to quantify interactions of soil and leaf nutrients on sugarcane grown on a Terra Ceia muck (Euic, hyperthermic Typic Medisaprist) that had previously received calcium silicate slag. Slag was applied at five rates, and yields were evaluated from plant, first-ratoon, and second-ratoon (stubble) crops at two locations. Soil and leaf from each crop were sampled for nutrient analysis and the results were used to interpret the yield data. Although slag increased cane yield by as much as 39% and sugar yield by 50%, for each 100 mg L^–1 drop in extractable soil Mg, cane yields declined by 5.3 Mg ha^–1 and sugar yields by 0.9 Mg ha^–1. At leaf Si concentrations exceeding 10 g kg^–1, optimum cane and sugar yields were observed, while leaf Mg concentrations approached critical leaf concentrations below 1.5 g kg^–1. Estimates of total leaf nutrient uptake during each crop indicated that uptake of Mg did not meet nutrient demands at high biomass production. Nutrient antagonism between Si and Mg is suggested. Low soil Mg may contribute to the marked crop responses to slag and for the decline in stubble production. Application of a magnesium fertilizer may be necessary to maintain high nutrient availability.Contribution from the University of Florida, Institute of Food and Agricultural Sciences. Florida Agric. Exp. Stn., Journal Series no. R-00859.     

包膜控释尿素对大棚辣椒的增产及土壤肥力效应的研究

对施用包膜控释尿素的大棚辣椒进行了田间试验,并对辣椒的品质进行了测试分析。结果表明:控释尿素与普通尿素相比有显著的增产效果,D90产量最高为34.83thm-2,比对照增产10.51thm-2,增产率为43.2%;比尿素增产6.59thm-2,增产率为23.3%;D60与普通尿素产量差异不显著;比对照增产5.68thm-2,增产率为23.4%;控释尿素具有增加单株果数、单果重的效果和增强辣椒生长的作用;辣椒施用控释尿素的硝酸盐含量最低,普通尿素最高;Vc和可溶性糖含量均以控释尿素为最高,普通尿素最低。综合品质指标依次为:控释尿素>普通尿素。说明控释尿素具有提高蔬菜品质的突出效应,特别在提高蔬菜的安全品质方面贡献最大。控释尿素的施用可增强土壤多酚氧化酶活性、磷酸酶、脲酶活性,特别能协调氮、磷、钾养分供应的平衡性,土壤酶活性的高低可以反映土壤养分转化的强弱。综合各项,在辣椒生产中以选用D90包膜控释尿素为最好,并适当配合D60和普通尿素。     

对流层散射最坏月转换模式研究

针对目前的最坏月预测模型无法有效反映对流层散射传输损耗的最坏月时间概率分布随地域和气象气候条件变化的特点,结合ITU-R P.617-3和ITU-R P.841-4建议书给出的最坏月预测模型,提出了一种对流层散射传输损耗最坏月时间概率预测方法。通过合理的数学推演和数值优化,该方法得到了对流层散射最坏月与年平均传输损耗的时间概率转换与地面折射率Ns的对应关系。该方法不仅解决了上述2种ITU模型的缺点,而且更加简单实用,适用范围更广。随后,为了验证该方法的准确性和全球适用性,利用该方法模拟了全球对流层散射数据库中各实验链路典型概率(50%、90%、99%)下的最坏月传输损耗,并与实测值和ITU-R P.841模型进行了对比验证。研究结果对对流层散射传播的发展和应用有一定的参考价值。