Study of the energy response of high pressure ionization chamber for high energy gamma-ray

The energy response calibration of the commonly used high pressure ionization chamber is very difficult to obtain when the gamma-ray energy is more than 3 MeV. In order to get the calibration of the higher part of the high pressure ionization chamber, we use the Fluka Monte Carlo program to perform the energy response in both the spherical and the cylindrical high pressure ionization chamber which are full of argon gas. The results compared with prior study when the gamma-ray energy is less than 1.25 MeV. Our result of Monte Carlo calculation shows agreement with those obtained by measurement within the uncertainty of the respective methods. The calculation of this study is significant for the high pressure ionization chamber to measure the high energy gamma-ray.     

清华汤姆逊散射X射线源初步实验研究

汤姆逊散射X射线源利用高亮度的相对论电子束与超短TW级激光相互作用,能产生能量可调、脉冲长度短（～100飞秒量级）的准单色高能X射线,在超快物理过程研究和医学领域具有广泛的应用前景。清华大学工程物理系加速器实验室正在积极筹建基于光阴极微波电子枪和飞秒强激光的汤姆逊散射实验平台,并利用实验室现有的16MeV返波行波加速器和Nd:YAG纳秒调Q激光系统进行了初步实验研究。在解决实验中出现的电磁干扰和韧致辐射X射线本底干扰等问题后,在实验中测量到了脉宽为6纳秒、脉冲光子产额为1.7x 10^4 的散射光子信号。在本文中将对实验装置和结果进行详细介绍。     

Influence of Dopant Concentration on Electroluminescent Performance of Organic White-Light-Emitting Device with Double-Emissive-Layered Structure

A novel phosphorescent organic white-light-emitting device （WOLED） with contiguration of ITO/NPB/CBP： TBPe：rubrene/Zn（BTZ）2：Ir（piq）2（acac）/Zn（BTZ）2/Mg：Ag is fabricated successfully, where the phosphorescent dye bis （1-（phenyl）isoquinoline） iridium （Ⅲ） acetylanetonate （Ir（piq）2 （acac）） doped into bis-（2-（2-hydroxyphenyl） benzothiazole）zinc （Zn（BTZ）2） （greenish-blue emitting material with electron transport character） as the red emitting layer, and fluorescent dye 2,5,8,11-tetra-tertbutylperylene （TBPe） and 5,6,11,12-tetraphenyl-naphthacene （rubrene） together doped into 4,4＇-N,N＇-dicarbazole-biphenyl （CBP） （ambipolar conductivity material） as the blue-orange emitting layer, respectively. The two emitting layers are sandwiched between the hole-transport layer N ,N＇-biphenyl-N , N＇-bis （1-naph thyl）-（1,1＇-biphenyl）-4, 4 Cdiamine （NP B） and electron-transport layer （Zn（BTZ）2 ） The optimum device turns on at the driving voltage of 4.5 V. A maximum external quantum efficiency of 1.53%. and brightness 15000 cd/m^2 are presented. The best point of the Commission Internationale de 1＇Eclairage （CIE） coordinates locates at （0.335, 0.338） at about 13 V. Moreover, we also discuss how to achieve the bright pure white light through optimizing the doping concentration of each dye from the viewpoint of energy transfer process.     

Synthesis and Bioactivity Evaluation of Novel N-Pyridylpyrazolemethanamine Derivatives

To further explore the structure-activity relationship(SAR) of amide bridge moeity of anthranilic diamides derivatives, a series of N-pyridylpyrazole derivatives was designed, synthesized and their biological activities were evaluated. The chemical structures of novel target compounds were confirmed by ¹H nuclear magnetic resonance (NMR), ¹³C NMR and elemental analyses(EA). Bioassay results of insecticidal activity demonstrated that the target compound 6h displayed 70% lethality rate against oriental armyworms at 200 mg/L. Moreover, most compounds displayed moderate to excellent antifungicidal activities against Fusarium oxysporum f. sp. cucumerinum, Cercospora arachidicola Hori, Botryosphaeria dothidea, Alternaria solani, Gibberella zeae and Phytophthora capsici at 50 mg/L. In particular, compound 6e showed 61.5% and 92.3% inhibition rate against Cercospora arachidicola Hori and Botryosphaeria dothidea, which was superior to the commercial positive control Chlorothalonil. These results will provide a potential clue for exploring novel high-effective agrochemicals.     

立方五次方非线性薛定谔方程的动力学及模式漂移

利用辛算法研究立方五次方非线性薛定谔方程的动力学,讨论随着五次方系数的增大方程的动力学性质.在相图中计算得到同宿轨交叉和椭圆轨道,系统具有周期解.讨论方程的解模式的漂移,结果表明解模式的漂移速度随着五次方系数的增大而减慢.     

基于蚁群算法的室内可见光高精度三维定位系统

为了提高室内定位精度,实现三维定位,提出一种基于蚁群算法的的可见光通信室内高精度三维定位系统。本系统采用了码分多址(Code Division Multiple Access,CDMA)调制技术,解决了室内可见光通信多信号源之间的符号间干扰.系统中与发光二极管(Light Emitting Diode,LED)光信号源地理位置相关的ID信息码经过直接扩频调制后加载至发光二极管驱动电路,以光信号的形式在室内传播.光信号经过放大、滤波、采样处理后,根据码分多址调制技术中扩频码的正交性恢复出ID信息及光强衰减信息.经过计算获得来自不同发光二极管的信号光强衰减因子,利用蚁群算法的全局搜索性确定最优定位点.引入误差修复因子,利用蚁群算法的并行搜索性对光强衰减因子偏差进行修正.仿真结果表明,信噪比为30dB,20dB,10dB的条件下,算法的定位精度分别为2cm,4cm,8cm.当计算的精度高于45cm时,蚁群算法定位解的搜索效率明显高于遍历法.在10dB的信噪比条件下,对光强衰减因子进行修正后100%的测试点都实现了5cm定位精度.实验结果表明,20dB信噪比条件下,92.59%的测试点的定位误差小于8cm,96.29%的测试点定位误差小于10cm,最大定位误差为11.30cm.经过误差修复后,96.2%的测试点实现了3cm的定位精度,61.6%的测试点实现了2cm的定位精度.本算法在实现了高精度定位,减少了获得最优定位解的计算量.     

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采用Ritz近似法建立客运专线下承式系杆拱桥侧向稳定承载力实用计算公式; 假定满足拱桥侧向弯扭边界条件的位移试函数, 建立系杆拱桥的主拱肋侧倾失稳结构势能的表达式,基于最小势能原理建立了下承式系杆拱桥侧倾失稳临界载荷实用计算公式. 采用该实用计算公式计算了某客运专线下承式系杆拱桥弹性侧向稳定承载力, 并与三维有限元屈曲计算结果进行比较, 结果表明: 该方法简单实用, 可准确地预测系杆拱桥侧倾临界载荷, 便于工程应用.     

石墨填充高密度聚乙烯基复合材料导热性能的研究

选用导热系数较高的无机填料石墨对高密度聚乙烯(HDPE)进行填充改性;采用偶联剂和磨盘型力化学反应器对石墨进行表面处理,提高石墨与聚合物基体的界面相互作用;用自行研制的升温速率测定装置测试材料的导热性能,并研究材料的导热机理;用SEM观察复合材料的微观形态.实验结果表明:经偶联剂处理后,石墨在HDPE中均匀分布;测试试样的上表面温度随时间的变化可用三次多项式T=A₀+A₁t+A₂t²+A₃t³拟会;HDPE/石墨复合材料升温速率随石墨含量增加而增大;石墨含量为35％的复合材料最大升温速率为HDPE的1.75倍.     

SO42-/ZrO2和SO42-/Al2O3-ZrO2催化剂上的正戊烷反应

研究了添加Al对SO₄^2-/ZrO₂超强酸样品的晶化、比表面、硫含量、超强酸性和正戊烷反应性能的影响,考察了活化温度、反应温度、Al含量和载Pt对催化剂活性和选择性的影响.SO₄^2-/Al₂O₃ZrO₂催化剂的酸强度与SO₄^2-/ZrO₂基本相当,但超强酸位比后者多,未载Pt时正戊烷反应活性和稳定性明显高于后者.负载Pt后,正戊烷异构化选择性和稳定性大大提高,但Pt/SO₄^2-/Al₂O₃ZrO₂催化剂的反应活性与Pt/SO₄^2-/ZrO₂相近,Al的促进作用不明显.     

时变参数系统的非完全分岔及其在Duffing方程中的应用

提出新的方法从本质上研究时变参数系统的非完全分岔问题。通过建立时变参数系统的解的线性近似定理去分析时变分岔方程运动的分岔转迁滞后和跃迁现象。利用Ｖ函数预测分岔转迁值,将新方法应用于Ｄｕｆｆｉｎｇ方程,获得一些新的分岔结果和关于解对初值和参数的敏感性结论。