Analysis of atmospheric particular matter and water using atomic emission spectrometry with inductively-coupled plasma and two-jet plasmatron

Summary A method for the atomic emission spectrometric analysis of air and water with inductively coupled and two-jet direct current plasmas has been developed. The method has been applied to the determination of impurity contents with good accuracy and sensitivity.     

一种简易可靠的射频激光调制器

采用ＰＩＮ电调衰减器、ＴＬ４９４等元件组成了射频（ＲＦ）大功率ＣＯ２激光调制器，调制频率、占空比和调制度单独可调。给出了电路的工作原理和测试结果。     

小型全内腔脉冲Ar~＋激光管的研制

介绍一种小型全内腔脉冲Ａｒ＋激光管的设计和结构。并对不同阴极，放电管直径，激励电压及Ａｒ气压等对输出功率及激光管寿命的影响作了一系列的实验，试制出结构简单，使用方便，价格便宜的有一定实用价值的小型全内脏脉冲Ａｒ＋激光管。     

自适应相位制中波同步广播及现场试验

在本试验中，采用智能同步广播激励器和ＣＣＴＶ传输的１ＭＨｚ标频，实现了中波同步广播同频保护率趋于０ｄＢ．并提出了自适应相位跟踪同步的概念。     

On error bounds for lower semicontinuous functions

We give some sufficient conditions for proper lower semicontinuous functions on metric spaces to have error bounds (with exponents). For a proper convex function f on a normed space X the existence of a local error bound implies that of a global error bound. If in addition X is a Banach space, then error bounds can be characterized by the subdifferential of f. In a reflexive Banach space X, we further obtain several sufficient and necessary conditions for the existence of error bounds in terms of the lower Dini derivative of f. Received: April 27, 2001 / Accepted: November 6, 2001?Published online April 12, 2002     

A circular crossed-field amplifier for in situ measurements, studyof reentrant beam effects, and comparison with numerical simulation

A low frequency, injected beam, circular format crossed-field amplifier has been designed and constructed for the purpose of studying electron-radio frequency wave interaction in reentrant devices. The device has been designed to allow in situ diagnostic probe measurements in the space between the anode and sole. The device has been operated in nonreentrant, fully reentrant, and reentrancy controlled configurations. Details of the design and operating parameters are described. Device characteristics are examined with respect to the amount of circulating charge or degree of reentrancy. A large increase in gain has been achieved from nonreentrant to the fully reentrant format. A gain of 7.2 dB has been obtained for the latter whereas only 3.8 dB has been obtained for the former with 30 mA of injected beam current. A maximum gain of 14.4 dB has been achieved for the fully reentrant configuration. Electron beam and noise measurements versus the degree of reentrancy have also been examined. Results from the nonreentrant amplifier performance have been directly compared with the MASK simulation code and good agreement has been obtained. These experiments will provide the basis for more detailed investigations on the effect of reentrancy on CFA operation and will also allow for the development of more accurate computer models of the reentrant system for numerical simulation of CFA operation     

HfOxNy的场发射特性

用直流溅射和高温退火相结合的方法制备了HfOxNy薄膜并测试了其场发射性能,发现其具有较低的开启电场、较大的发射电流密度以及很好的发射稳定性.高压"锻炼"对提高HfOxNy场发射性能起着关键作用,这与高压"锻炼"下薄膜内部结构和表面性质的改变有关.对场发射机理的研究表明,HfOxNy的场发射符合经典的FN隧穿理论.     

Efficient 3-d capacitance extraction considering lossy substrate with multilayered green's function

An efficient algorithm for extraction of three-dimensional (3-D) capacitance on multilayered and lossy substrates is presented. The new algorithm presents a major improvement over the quasi-3-D approach used in a Green's function-based solver and takes into consideration the sidewalls of 3-D conductors. To improve the efficiency of the computation and the transformation of the Green's function, a nonuniform grid is adopted. The most computationally intensive part in the transformation of the Green's function is computed separately as technology-independent matrices Tk foremost. Once computed, Tk can be stored and used for any technology, thus the storage requirement and computational complexity are reduced from O (S/sup 2/) and O (S/sup 2/ log S/sup 2/), respectively, to just O [(log S/sub max/)/sup 2/]. Extensive tests have been performed to verify the new algorithm, and its accuracy has been established by comparing with other programs.     

网上协作学习模式研究

主要针对网上协作学习的基本模式、实现方式和存在的问题进行了初步研究。     

Dynamic bandwidth allocation for quality-of-service over Ethernet PONs

Ethernet-based passive optical network (EPON) technology is being considered as a promising solution for next-generation broadband access networks due to the convergence of low-cost Ethernet equipment and low-cost fiber infrastructures. A major feature for this new architecture is the use of a shared transmission media between all users; hence, medium access control arbitration mechanisms are essential for the successful implementation of EPON: i.e., to ensure a contention-free transmission and provide end users with equal access to the shared media. We propose to use the multipoint control protocol defined by the IEEE 802.3ah task force to arbitrate the transmission of different users, and we present different dynamic bandwidth allocation (DBA) algorithms to allocate bandwidths effectively and fairly between end users. These DBA algorithms are also augmented to support differentiated services, a crucial requirement for a converged broadband access network with heterogeneous traffic. We show that queueing delays under strict bandwidth allocation algorithms result in an unexpected behavior for certain traffic classes, and we suggest the use of DBA with appropriate local queue management to alleviate this inappropriate behavior. We conduct detailed simulation experiments to study the performance and validate the effectiveness of the proposed protocols.