EAST低温系统又一新降温模式

EAST氦低温系统是EAST(Experimental Advanced Super-conducting Tokamak)先进超导托卡马克实验装置重要子系统之一;到目前为止,EAST已经成功进行了6次降温实验。第四次降温实验于2008年8月完成,这次降温实验与前几次降温实验很不相同。前3次的降温实验冷却磁体依赖四台透平膨胀机(透平A、B、C和D),透平B、C和D获得LHe去冷却PF和TF磁体、5&8对电流引线和busline到相应的温度。透平A用于制取80K的冷量冷却外冷屏。而此次降温是采用3台透平膨胀机(透平A、B和C),透平B和C与节流阀获得LHe去冷却PF和TF磁体、5&8对电流引线和busline到相应的温度。透平A还是用于制取80K的冷量冷却外冷屏。此次整个降温过程大概用了20天,比以前多耗时25%;文中给出了透平的启动过程、磁体冷却过程和一些操作经验。     

Infinitely many coexisting conservative flows in a 4D conservative system inspired by LC circuit

Nonlinear Dynamics - Conservative chaotic flows, a category of incompressible chaos, are usually generated from dynamical systems without dissipation. The existing results on conservative chaos are...     

导向相应功率定位中时延不确定项的影响

在分布式传声器网络应用中,可控波束形成器导向相应功率(SRP)声源定位算法受到导向时延不准确的影响导致定位不稳定.将导向时延不确定项引入SRP定位模型,并对引起不确定项的主要干扰因素进行了分析建模,同时提出了应对导向时延不确定项的SRP定位算法.蒙特卡罗仿真和分析表明该算法具有抑制噪声和降低定位误差的效果,实际实验数据...     

石油沥青质在烃中的稳定性研究

石油是以沥青质为分散相的非水胶体体系[1,2 ] 。研究认为 ,石油中沥青质的沉淀和絮凝 ,对石油开采及输送有十分重要的影响 [3]。提高沥青质在石油中的胶体稳定性 ,可强化石油加工过程中的重油减压蒸馏、催化裂化、减粘裂化及延迟焦化等过程[1,2 ] ,是提高炼厂轻质油收率、改善产品质量、提高综合经济效益的重要途径。国外关于沥青质在烃类介质中的稳定性研究报道较多 ,大多侧重于胶质对沥青质的稳定作用。由于胶质和沥青质均为由多种复杂结构分子组成的混和物 ,探讨胶质对沥青质的稳定机理极端困难 ,Chia-Lu Chang[4 ]等定量讨论了沥青质…     

Comparison of thermal ionization mass spectrometry and Multiple Collector Inductively Coupled Plasma Mass Spectrometry for cesium isotope ratio measurements

In the nuclear domain, precise and accurate isotopic composition determination of elements in spent nuclear fuels is mandatory to validate neutron calculation codes and for nuclear waste disposal. The present study presents the results obtained on Cs isotope ratio by mass spectrometric measurements. Natural cesium is monoisotopic (¹³³Cs) whereas cesium in spent fuels has 4 isotopes (¹³³Cs, ¹³⁴Cs, ¹³⁵Cs, and ¹³⁷Cs). As no standard reference material is available to evaluate the accuracy of Cs isotopic measurements, a comparison of cesium isotopic composition in spent nuclear fuels has been performed between Thermal Ionization Mass Spectrometry (TIMS) and a new method involving Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) measurements. For TIMS measurements, isotopic fractionation has been evaluated by studying the behavior of cesium isotope ratios (¹³³Cs/¹³⁷Cs and ¹³⁵Cs/¹³⁷Cs) during the analyses. For MC-ICPMS measurements, the mass bias effects have been corrected with an external mass bias correction using elements (Eu and Sb) close to cesium masses. The results obtained by the two techniques show good agreement: relative difference on ¹³³Cs/¹³⁷Cs and ¹³⁵Cs/¹³⁷Cs ratios for two nuclear samples, analyzed after chemical separation, ranges from 0.2% to 0.5% depending on the choice of reference value for mass bias correction by MC-ICPMS. Finally the quantification of the ¹³⁵Cs/²³⁸U ratio by the isotope dilution technique is presented in the case of a MOx (mixed oxide) spent fuel sample. Evaluation of the global uncertainties shows that this ratio could be defined at an uncertainty of 0.5% (k = 2). The intercomparison between two independent mass spectrometric techniques is fundamental for the evaluation of uncertainty when no isotopic standard is available.     

公平的知识签名

针对一般的知识签名不能避免隐秘通信的发生这一问题,提出了知识签名的公平件概念,并给出了严格的定义.利用知识的公平的零各识证明,构造了一个公平的知识签名方案,最后证明了此签名方案可有效地保证公平性,从而避免隐秘通信的发生.     

Synthesis and fungicidal activity of novel strobilurin analogues containing substituted N-phenylpyrimidin-2-amines

A number of novel strobilurin analogues containing substituted N-phenylpyrimidin-2-amines were synthesized.The structures of these new compounds were confirmed by ~1H NMR,IR and elemental analysis.Biological evaluation in the greenhouse showed several compounds have good fungicidal activities at 25 mg/L.     

标准模型下可否认的群密钥协商协议

给出了一个标准模型下可证明安全和可证明可否认性的高效的群密钥协商协议,并基于DDH假设和伪随机函数集的存在性假设一同给出了其安全证明和可否认性证明.本文的安全分析对于研究群密钥协商协议在各种特殊的应用环境下所需要的各种不同安全特性有所帮助,其证明方法也能够对其他密钥协商协议的安全证明有启发性的作用.