Study of sintered stainless steel fiber felt as gas diffusion backing in air-breathing DMFC

Adoption of a sintered stainless steel fiber felt was evaluated as gas diffusion backing in air-breathing direct methanol fuel cell (DMFC). By using a sintered stainless steel fiber felt as an anodic gas diffusion backing, the peak power density of an air-breathing DMFC is 24 mW cm(-2), which is better than that of common carbon paper. A 30-h-life test indicates that the degraded performance of the air-breathing DMFC is primarily due to the water flooding of the cathode. Twelve unit cells with each has 6 cm(2) of active area are connected in series to supply the power to a mobile phone assisted by a constant voltage diode. The maximum power density of 26 mW cm(-2) was achieved in the stack, which is higher than that in single cell. The results show that the sintered stainless steel felt is a promising solution to gas diffusion backing in the air-breathing DMFC, especially in the anodic side because of its high electronical conductivity and hydrophilicity. (C) 2004 Elsevier B.V. All rights reserved.

Monostable-Bistable Transition Logic Element (MOBILE) Model for Single-Electron Transistors

The traditional monostable-bistable transition logic element (MOBILE) structure is usually composed of resonant tunneling diodes (RTD). This letter describes a new type MOBILE structure consisting of single-electron transistors (i.e. SET-MOBILE). The analytical model of single-electron transistors ( SET) has been considered three states (including an excited state) of the discrete quantum energy levels. The simulation results show negative differential conductance (NDC) characteristics in I-DS-V-DS curve. The SET-MOBILE utilizing NDC characteristics can successfully realize the basic logic functions as the RTD-MOBILE.

mobile agent system model based on servlet technology

A mobile agent system model based on the servlet technology is presented, the constitution and working process of the system are analyzed. The implementation of key parts of this model and the current development situation as well as the development trend of mobile agent technology are introduced. The mobile agent system model enhances its internal structure recognition and facilitates the system expansion and reformation. The remotely mobile agent control method by means of the protocol modification is presented.

cryptanalysis of the end-to-end security protocol for mobile communications with end-user identification/authentication

IEEE Computer Society

gcs-ma: a group communication system for mobile agents

Reliable messaging is a key component necessary for mobile agent systems. Current researches focus on reliable one-to-one message delivery to mobile agents. But how to implement a group communication system for mobile agents remains an open issue, which is a powerful block that facilitates the development of fault-tolerant mobile agent systems. In this paper, we propose a group communication system for mobile agents (GCS-MA), which includes totally ordered multicast and membership management functions. We divide a group of mobile agents into several agent clusters,and each agent cluster consists of all mobile agents residing in the same sub-network and is managed by a special module, named coordinator. Then, all coordinators form a ring-based overlay for interchanging messages between clusters. We present a token-based algorithm, an intra-cluster messaging algorithm and an inter-cluster migration algorithm to achieve atomicity and total ordering properties of multicast messages, by building a membership protocol on top of the clustering and failure detection mechanisms. Performance issues of the proposed system have been analysed through simulations. We also describe the application of the proposed system in the context of the service cooperation middleware (SCM) project.

Formalization and specification for controlling process modularity in mobile computing

新的计算模式，普适计算和全局计算，正在作为高度分布式和移动计算的计算模式展现出来。这篇论文探讨了在抽象层面上支持这些新型计算模式的适合的形式化基础，关注在进程移动单位上的控制, 以便在分布式与移动计算环境下更好地协调进程的移动性。 论文的第一部分概述了针对分布式、移动计算的现有进程演算模型中的进程移动单元，并且设计了一种在此方面更优、更具弹性的进程框架。为了表示这种进程框架，我们提出了一种新的、针对移动和分布式系统的进程演算,这种进程演算的优点是动态、弹性的控制进程的移动单元；具体的思路就是扩展π- calculus以及其支持分布式和移动性的变体。我们把这种新的演算叫做Modular π-calculus。我们通过这种演算的提出来说明进程框架提供了一种针对移动进程更为合适的协调机制以及编程模型，例如移动的代理和动态组件载入的支持。之后，我们通过讨论互模拟的几种提法来具体说明能够反映演算设计的进程描述的关键，之后我们讨论了它们的具体性质。 本文的第二部分提出了一个对进程模型的行为和性质进行推理的规约框架。首先，提出了一个对Modularπ-calculus中进程的系统性质进行规约的模态逻辑。为了更好的理解该逻辑，文中对由这个逻辑推出的进程等价的特征进行了研究，并且证明了该逻辑的区分能力介于互模拟和结构一致之间。接下来关于这个规约框架的自动化，本文针对该逻辑和Modular π-calculus的有限控制子集，提出了模型检测算法，并且给出了算法正确性的证明。同时文中贯穿了一些实际且直观的例子，以展现本文提出的一组框架即演算、逻辑和模型算法的有效性。

An Obstacle Cluster Based Data Fusion Method for Mobile Robot

首先给出了一种通过融合多个超声波传感器和一台激光全局定位系统的数据建立机器人环境地图的方法 ,并在此基础上 ,首次提出了机器人在非结构环境下识别障碍物的一种新方法 ,即基于障碍物群的方法 .该方法的最大特点在于它可以更加简洁、有效地提取和描述机器人的环境特征 ,这对于较好地实现机器人的导航、避障 ,提高系统的自主性和实时性是至关重要的 .大量的实验结果表明了该方法的有效性 .