Performance evaluation on a double‐layered satellite network

How to evaluate the performance of satellite networks is a prerequisite to the construction of satellite networks, and is also one of challenges in the researches on satellite networks. In this paper, generalized stochastic Petri net (GSPN) models are presented to carry out the performance analysis of a double‐layered satellite network. Firstly, the GSPN model of a double‐layered satellite network is simplified by proper analysis. Then, two sets of experiments are conducted to analyse the performance of the satellite networks, and show that the double‐layered satellite network outperforms single‐layered ones on the heavy traffic load. Finally, the feasibility and effectiveness of the proposed approach is verified by simulation experiments. Copyright © 2005 John Wiley & Sons, Ltd.     

Some New uniform frames with block size four and index one or three

In this paper, some new uniform frames with block size four and index one or three are obtained. The known existence results for (4,1)‐frames and (4,3)‐frames are both improved to the extent that only a finite number of possible exceptions remain. © 2003 Wiley Periodicals, Inc.     

CO2相干激光多普勒测速的研究

叙述运用ＣＷＣＯ２相干激光雷达测量运动目标速度的原理和实验装置，并给出了实验结果，测速精度为０．０１ｍ／ｓ速度分辨率为０．０５ｍ／ｓ，外场实验表明，对于漫射目标，作用距离２００ｍ。     

胶束薄层色谱法测定食品及药用胶囊中的合成食用色素

在聚酰胶片上以13%SDBS(十二烷基苯磺酸钠)+7%Triton X-100〔聚乙二醇-对-(1.1,3,3-四甲基)丁基苯基醚〕+(2+3)氨水(1+5+1)为展开剂,用胶束薄层色谱法分离和测定了柠檬黄、亮蓝、苋菜红、胭脂红和赤藓红。测定波长分别为440、632、535、525和528 nm,线性范围分别为0.1～2、0.05～1、0.05～1、0.05～1和0.05～1μg/斑点。方法用于测定软饮料糖果及药用胶囊中的合成色素,获得了满意的结果。此外,还对展开剂的最佳组成进行了单纯形法优化。     

镁掺杂对In2O3电导和气敏性能的影响

用共沉淀法制备了Mg2 + 掺杂的In2 O3 纳米粉 ,研究了镁掺杂对In2 O3 电导和气敏性能的影响 .结果表明 :MgO和In2 O3 间可形成有限固溶体In2 -xMgxO3 (0≤x≤ 0 .40 ) ;MgIn× 电离的空穴对材料导带电子的湮灭 ,使掺镁纳米粉的电导变得很小 ;n(Mg2 + )∶n(In3 + ) =1∶2共沉淀物于 90 0℃下热处理 4h ,用所得的纳米粉制作的传感器在 32 0～ 370℃下 ,对 45 μmol/LC2 H5OH的灵敏度达 10 2 .5 ,为相同浓度干扰气体Petrol的 12倍多 .     

A flow tube study of methyl iodine uptake on soot surface

The black carbon aerosols are now recognized for their potential impact on climate and the halogenated compounds are thought to be very important in atmospheric chemistry. However, there are very few studies on the interactions between soot aerosols and halogenated compounds. We report the measurement of the uptake of CH₃I on soot. The measured uptake coefficient is 0.0103 ± 0.0015 at a total pressure of 2–4 Torr and 298 K. The results suggest that the uptake of CH₃I occurs efficiently on soot particles. The present work suggests that heterogeneous loss of CH₃I on soot may influence the concentration of CH₃I throughout the atmosphere.     

First Total Synthesis of 12-Hydroxy-13-methylpodocarpa-9, 11, 13-trien-3-one

12-Hydroxy-13-methylpodocarpa-9, 11, 13-trien-3-one 9 was isolated from the twigs ofCroton salutaris1. Many diterpenes exhibit significant bioactivities, such as antibac-terial and antitumour and 9 has a rare structure. In order to study the relationshipb…     

添加助剂的钙钛矿型氧化物NdMO_3上的甲烷氧化偶联——Ⅱ.15% Li_2O/NdMO_3(M=Cr、Mn、Fe、Co、Ni)上的OCM反应研究

在添加了15%Li_2O的NdMO_3(M=Cr、Mn、Fe、Co、Ni)上进行了甲烷氧化偶联(OCM)反应研究.通过改变反应气中CH_4:O_2浓度比,在氧化态和“脱氧态”催化剂上的CH_4脉冲反应,探讨了表面吸附氧和晶格氧在OCM反应中的作用以及NdMO_3中不同金属离子(M)对OCM反应活性的影响等.     

激光技术推广应用中安全防护问题

论述加强激光安全防护工作的紧迫性,介绍我国激光安全工作的进展,提出下一步工作建议。