Hybrid phase-locked loop with fast locking time and low spur in a 0.18-μm CMOS process

We propose a novel hybrid phase-locked loop(PLL) architecture for overcoming the trade-off between fast locking time and low spur. To reduce the settling time and meanwhile suppress the reference spurs, we employ a wide-band single-path PLL and a narrow-band dual-path PLL in a transient state and a steady state, respectively, by changing the loop bandwidth according to the gain of voltage controlled oscillator(VCO) and the resister of the loop filter. The hybrid PLL is implemented in a 0.18-μm complementary metal oxide semiconductor(CMOS) process with a total die area of1.4×0.46 mm2. The measured results exhibit a reference spur level of lower than-73 dB with a reference frequency of10 MHz and a settling time of 20 μs with 40 MHz frequency jump at 2 GHz. The total power consumption of the hybrid PLL is less than 27 mW with a supply voltage of 1.8 V.     

Electrooxdation of Tricarbonyl(N,N-Diphenylcyclohexadienecarboxamide)Iron Complexes. Reversibility of Electron Transfer and Free Energy Change

Qualitative and quantitative criteria of irreversibility of electron transfer in cyclic voltammetry (CV) of tricarbonyl(N,N-diphenylcyclohexadienecarboxamide)iron complexes were investigated. The measurement of the heterogeneous rate constants for electron transfer according to CV data over an extended range of free energy change ( ΔG) for these complexes are described. Kinetic analyses of the electrochemical technique demonstrates that when the applied potential exceeds the standard potential E°, the experimental rate constant k_e represents an accurate measurement of the intrinsic rate constant k₁ for electron transfer. However, as the applied potential is less than E°, the reversibility of the electron-transfer process becomes increasingly more important, and the rate constants for reverse electron transfer k_-t and decomposition k₂ of the electrogenerated intermediate have to be taken into account.     

Response of colloidal liquids containing magnetic holes of different volume densities to magnetic field characterized by transmission measurement

This paper systematically investigates the response of colloidal liquids containing magnetic holes of different volume densities to magnetic field by conventional transmission measurements. It finds that the enhancement in the transmission of such a colloidal liquid under a magnetic field exhibits a strong dependence on the volume density of magnetic holes. A linear increase in the maximum enhancement factor is observed when the volume density of magnetic holes is below a critical level at which a maximum enhancement factor of ～150 is achieved in the near infrared region. Once the volume density of magnetic holes exceeds the critical level, a sharp drop of the maximum enhancement factor to ～2 is observed. After that, the maximum enhancement factor increases gradually till a large volume density of ～9%. By monitoring the arrangement of magnetic holes under a magnetic field, it reveals that the colloidal liquids can be classified into three different phases, i.e., the gas-like, liquid-like and solid-like phases, depending on the volume density of magnetic holes. The response behaviour of colloidal liquids to magnetic field is determined by the interaction between magnetic holes which is governed mainly by their volume density. A phase transition, which is manifested in the dramatic reduction in the maximum enhancement factor, is clearly observed between the liquid-like and solid-like phases. The optical switching operations for colloidal liquids in different phases are compared and the underlying physical mechanisms are discussed.     

Offline Calibration of BES Ⅱ Muon Detector

The Structure of BES Ⅱ μ Detector and its original offline calibration method is introduced, The calibration method is improved after careful study of the basic principle of various offline calibration method and the main reasons which caused the z position resolution of the μ Detector worsened. Using the improved offline calibration method, the z position resolution of the μ Detector is improved about 20 % compared with the previous method.     

对甲氧基苯甲醛肟晶体结构、红外光谱及分子间相互作用的实验与理论研究

从实验和理论两个方面研究了Z型和E型对甲氧基苯甲醛肟晶体的熔点、 结构、 红外光谱和分子间相互作用. 在E型和Z型晶体中, 对甲氧基苯甲醛肟分子分别呈二聚体重复单元和双链Zigzag结构排列. 研究结果表明, 电荷分布变化引起的静电相互作用差别、 形成氢键的方式和强度以及晶体中分子排列方式导致的范德华作用不同是造成Z型和E型对甲氧基苯甲醛肟固体熔点、 红外光谱等物理性质差别的根本原因.     

Eu3+掺杂的Sr2CeO4发光材料的光致发光研究

利用高温固相反应法制备了Eu³⁺掺杂的Sr₂CeO₄样品,并对其吸附水前后的光谱特性进行了研究.结果发现,对于刚制备的Sr_2-xEu_xCeO_4+x/2样品, 在Ce⁴⁺—O^2-的电荷迁移激发中,只有强激发带(～35700cm^-1)与Eu³⁺离子间存在能量传递,而弱激发带 (～29400cm^-1)只是引起Ce⁴⁺—O^2-的电荷迁移发射;在Sr_2-xEu_xCeO_4+x/2样品吸附水后,Eu³⁺的线状吸收跃迁强度显著增加, Ce⁴⁺—O^2-两个激发带均向Eu³⁺离子传递能量. Ce⁴⁺—O^2-强激发带通过交换作用向Eu³⁺离子传递能量,而弱激发带与Eu³⁺离子间的能量传递机理是非辐射多极子近场力的相互作用. 关键词： 2-xEu_xCeO_4+x/2')" href="#">Sr_2-xEu_xCeO_4+x/2 发光性质 能量传递 吸附水     

THE BES ON-LINE DATA ANALYSIS SYSTEM

The paper briefly describes the hardware configuration and software components of the BES (Beijing Spectromenter) on-line data acquisition system,and summarizes the development of this system we completed in the recent two years.A successful run of the on-line system has been performed in the BES'S cosmic ray test.     

氧化腈与丙炔1,3-偶极环加成反应中区域选择性的理论研究

用密度泛函(DFT)B3LYP/6-311＋＋G**方法研究了氧化腈(RCNO, R＝F, NO₂, OCH₃, OH, COOCH₃, CHO, CONH₂, H, CH₃)与丙炔的1,3-偶极环加成反应, 并且计算了不同温度下的反应速率常数, 讨论了氧化腈上不同取代基R的取代效应和温度对反应区域选择性的影响. 结果显示, 氧化腈与富电子亲偶极体——炔烃反应, 5-取代反应占优势; 氧化腈上取代基R为强吸电子基团时或在较高温度下, 有利于4-取代反应的进行.     

一种基于开口空心球的声学超材料

提出了一种基于局域共振的开口空心球(spilt hollow spheres,SHS)模型,数值计算和声学透射实验结果表明基于该模型的声学超材料可以实现负的弹性模量.为了说明SHS的局域共振性质,研究了微结构SHS几何尺寸(例如开口孔径d和空心球直径D)变化时材料的透射性质,结果表明SHS的几何尺寸的改变对声学超材料的透射吸收峰频率有显著影响.另外,还研究了SHS不同排列方式对透射行为的影响,发现单层样品中SHS单元数目以及晶格常数的变化不会引起谐振频率的变化,但是随着SHS单元数目或者样品 关键词： 开口空心球(SHS) 声学超材料 吸收峰 等效弹性模量     

Cluster formation in two-Yukawa fluids

We present a different and efficient method for implementing the analytical solution of Ornstein-Zernike equation for two-Yukawa fluids in the mean spherical approximation. We investigate, in particular, the conditions for the formation of an extra low-Q peak in the structure factor, which we interpret as due to cluster formation in the two-Yukawa fluid when the interparticle potential is composed of a short-range attraction and a long-range repulsion. We then apply this model to interpret the small angle neutron scattering data for protein solutions at moderate concentrations and find out that the presence of a peak centered at Q=0 (zero-Q peak) besides the regular interaction peak due to charged proteins implies an existence of long-range attractive interactions besides the charge repulsion.