单电子晶体管I-V特性数学建模

基于正统单电子理论，提出了单电子晶体管的I-V特性数学模型。该模型的优点是：它由实际物理参数直接获得；支持双栅极工作，更利于逻辑电路应用。I-V特性和跨导仿真结果证实了它的准确性。     

Pulse-Width Dependence in Current-Driven Magnetization Reversal Using GaMnAs-Based Double-Barrier Magnetic Tunnel Junction

We have investigated the current pulse width dependence on current-driven magnetization reversal in double-barrier structures using GaMnAs-based magnetic tunneling junctions (MTJ) in order to clarify the origin of low threshold current density for current-driven magnetization reversal. Comparing with the case of single-barrier MTJ, the pulse-width dependence reveals that threshold current density is reduced by double-barrier MTJ. We confirmed that the threshold current density in the order of 10⁴ A/cm² is estimated considering the effect of current pulse width.     

Scale Transition in Steel-Concrete Interaction. II:?Applications

The proposed mode of consideration of the steel-concrete interaction (Part I) is applied to real-life engineering structures. Two structures recently investigated numerically at Vienna University of Technology are considered: (1) the reinforced concrete (RC) cooling tower III Ptolema?s SES (Greece) and (2) a part of the shotcrete tunnel lining installed at the Lainzer tunnel (Austria). In both examples, the uniaxial fracture criterion used in Part I is replaced by the maximum stress (Rankine) criterion. Together with the Drucker-Prager criterion, which is used for the simulation of compressive failure of concrete/shotcrete, it defines the space of admissible stress states in the framework of multisurface plasticity. For the simulation of early-age fracture of shotcrete, consideration of the steel-concrete interaction presented in Part I of this paper is extended towards young shotcrete. Similar to the benchmark problem investigated in Part I of this paper, several analyses with different degrees of consideration of the steel-concrete interaction are performed. The obtained results give insight into the influence of the steel-concrete interaction on the load-carrying behavior of the investigated structures.     

IPv6过渡技术中ISATAP隧道研究与应用

ISATAP是具有多种优点的自动隧道技术,适合用于校园网IPv4/IPv6过渡中。给出ISA-TAP隧道技术机制的分析,并结合校园网设计ISATAP隧道,解决将多个实验室的主机接入CERNET2的过渡问题,详细介绍配置过程,所实现的ISATAP隧道能很好地进行IPv6通信。     

基于移动信息化的安全接入平台建设

为提高移动信息化接入的安全级别,保障组织内部业务的安全运作,在传统网络安全架构的基础上,使用第二层隧道协议和混合加密技术构建一个安全接入平台。根据平台的功能及其安全性,将移动信息化区域分为5类,并为每一类区域制定安全策略,使原本限制在内网中的业务系统可以安全地在移动终端上使用。实际应用结果表明,该平台可以保证用户身份的匿名性、数据机密性、数据完整性、数据新鲜性及不可抵赖性。     

Influence of Mesh Geometry on Three-Dimensional Finite-Element Analysis of Tunnel Excavation

Finite element (FE) analysis has become an important tool for predicting building response to tunnel-induced ground movement. Because tunnel construction is a three-dimensional (3D) process, the trend is to apply 3D FE analysis to tunnel-soil-building interaction problems instead of applying the plane-strain models that are commonly used in engineering practice. Since 3D FE analyses require large amounts of computational resources, the geometric dimensions of the 3D models are often kept to a minimum to reduce calculation time. There is, however, a lack of published information concerning appropriate mesh dimensions. This paper investigates the influence of the geometry and the dimension of a 3D FE model on tunnel-induced surface settlement predictions. The paper shows how the vertical boundaries can influence the results. It demonstrates that reasonable results can be obtained by increasing the length of incremental tunnel excavation and by scaling back the settlement values to give a required tunnel volume loss. This study therefore not only highlights the limitations of 3D modeling but also shows its potential for engineering practice.     

Investigation of Tunnel-Soil-Pile Interaction in Cohesive Soils

Underground tunnels are considered to be a vital infrastructure component in most cities around the world. Careful planning is always necessary to ensure minimum impact on nearby surface and subsurface structures. This study describes the experimental investigation carried out to examine the effect of existing piles installed in cohesive soil and extended to bedrock on the circumferential stresses developing in a newly constructed tunnel supported by a flexible lining system. A small scale testing facility was designed and built to simulate the process of tunnel excavation and lining installation in the close vicinity of preinstalled model piles. Lining stresses were measured for different separation distances between the lining and the existing piles Consistent decrease in the lining load was observed when the piles are located within a distance of one tunnel diameter from the tunnel. The results presented in this study indicated that measuring the lining response near existing pile foundations may be used to evaluate the extent of the interaction between the lining and the surrounding piles.     

新奥法施工特点及施工要点

新奥法是地下工程设计和施工中涌现出来的一种新技术.自七十年代后期传入我国后,很快就在水电、铁道、冶金、煤炭等部门推广应用.本文较为全面地介绍了新奥法施工特点和要点.     

CORBATunnel：一种支持CORBA与Web互操作的优化技术

提出了一种在Ｗｅｂ客户端实现ＣＯＲＢＡ客户端的互操作优化技术,即ＣＯＲＢＡＴｕｎｎｅｌ,使得客户端能够通过Ｗｅｂ服务器上的ＣＯＲＢＡ桥接器与后端的ＣＯＲＢＡ对象通信,达到减少网络流量的目的。在剖析ＩＩＯＰ协议冗余开销的基础上,介绍了优化方案和模型。     

一种基于范围的可靠移动组播算法

移动IP[1]提出了双向隧道和远程签署两种移动组播算法,各自有明显的优缺点.在以双向隧道为基础的改进算法RBMoM[4]中引入了服务范围的概念.提出移动组播算法在远程签署的基础上结合服务范围概念,寻求最优转发路径和最小组播树管理开销之间的折衷,并在节点移动时采用在移动代理间建立隧道的方式补充数据包,提高组播可靠性.对模拟结果的分析和比较显示该算法具有更好的综合性能.