Modification of Boundary Parameters and Fluctuations by IBW and LHCD in the HT-7 Tokamak

Measurements of boundary parameters and their fluctuations have been performed in ohmic (OH) plasma and Ion Bernstein Wave (IBW) and Lower Hybrid Current Drive (LHCD) enhanced confinement plasma using a pneumatically driven Langmuir probe array on HT-7 toka-maX. In the enhanced confinement plasma~ the gradients of electron density and temperature become higher and a transport barrier comes into being in the vicinity of the limiter. The boundary potential shows a clear modification in the same region. The fluctuation levels are significantly depressed and the coherences between fluctuations are reduced evidently in the enhanced plasma.Meanwhile, we obtained the spectral features and the poloidal phase velocity of fluctuations us-ing a two-point correlation technique and found obvious modifications of the turbulence and the poloidal flow. The results suggest that the improved confinement in the IBW and LHCD enhanced plasma is at least partially due to the modification of the boundary parameters and the suppression of the boundary fluctuations and fluctuation induced fluxes.     

Diameter协议的实现——Opendiameter软件体系结构分析

Diameter协议是IETF的AAA(认证、授权、记费)工作组针对RADIUS协议的不足,提出的下一代AAA协议,设计之初就充分考虑了可扩展性、移动性和安全性,必将在移动IP尤其是MIPv6中得到广泛应用。Opendiameter是IETF组织人员开发的开源软件,实现了Diameter协议,并为进一步的开发提供了API(应用编程接口)。文中描述了Diameter基础协议和部分应用协议,并在此基础上,重点分析了Opendiameter的体系结构、线程观、基本信息处理和提供的C API。     

一种基于构件的移动警务系统的扩展性设计

通过对业务扩展需求的分析,结合基于构件的软件开发方法思想,提出了一种基于构件的移动警务系统的扩展性设计方案,分别对客户端和服务端进行了构件化设计。在客户端设计上,抽象了一组警务系统专用的界面构件和事件处理构件;在服务端的设计上,抽象了一组警务系统专用的业务构件。改良后的系统在透明性、灵活性、高效性和扩展性等方面都得到了提高,使得终端用户更加便利。     

无线协作网络中一种高效的分布式安全中继选择方法

Cloud computing is always adopted to enhance the computing capability of mobile systems , especially when the mobile users prefer to use some computation intensive applications . Consequently, the distributed wireless relay infrastructure should be deployed to aid the traffic transmission. To further enhance the QoS provisioning goals of wireless cooperative network, this paper puts forward a multiobjective approach for distributed optimal relay selection, which takes Bit Error Rate (BER) and Secrecy Capacity (SC) into account simultaneously. Firstly, our proposal partitions the channel state into several levels according to the received signaltonoise ratio (SNR) and describes the timevarying Rayleigh fading channel characteristics by using first order finitestate Markov model. Secondly, we model the relay selection as Restless Multiarmed Bandit optimal solution problem with respect to the channel state and the state transition probability. Finally, simulation results demonstrate the efficiency of the proposed approach which outperforms the existing ones .     

MIMO+OFDM:新一代移动通信核心技术

新一代移动通信(beyond3G/4G)与第三代移动通信系统(3G)相比将会提供更高的数据传输速率,更低的成本。达到高速率低成本的一个技术前提就是高频谱效率的技术,从而可以在有限的频谱上提供更高的传输速率和系统容量,MIMO和OFDM就是这样的技术。二者的结合已经成为新一代移动通信技术研究中的热点。通过这两种技术的优势互补,可以为系统提供高达2~100Mbit/s的传输速率,同时也能提高系统容量,降低成本。本文将详细介绍这两种技术,并给出二者结合的方案。     

业务质量的用户满意度建模

为了管理电信业务,把属性数学理论引入电信业务管理领域,在业务质量的关键性能指标基础上利用属性集测度的概念定义了用户对电信业务质量的满意度,并以此为基础上从人类大脑感知事务的角度出发建立了1个衡量业务质量的用户满意度模型. 最后运用该模型对彩信业务质量进行了分析.     

自由状态冰对螺旋桨水动力性能的影响

为了研究自由状态冰条件下的冰桨非接触干扰,本文采用重叠网格与流体-固体相互作用方法分别对冰桨非接触模型中冰块位移以及螺旋桨水动力性能进行了模拟,与实验结果的对比证明了该方法的可行性.研究发现:自由状态冰后面存在"加速区"与"阻塞区",随着冰块的靠近,阻塞区对螺旋桨的影响增大;随进速系数的增加,螺旋桨的推力系数和扭矩系数...     

Bursty Behaviour of Turbulent Particle and Energy Fluxes in Edge Plasma of HT-7 Tokamak

High time resolution measurements of the electrostatic fluctuations and the turbulent particle and energy fluxes have been performed with a Langmuir probe array in the edge plasma in HT-7 tokamak. Bursty behaviour was observed in the time resolved turbulent fluxes with positive skewness and large kurtosis. The contribution of the large sporadic bursts to the transport losses were estimated. The analysis shows that the turbulent fluxes have different behaviour in different frequency domains and the probability distribution functions （PDFs） of the particle and energy fluxes present two distinct scaling ranges. All these are essentially consistent with the predictions of the self-organized criticality （SOC） model, though further studies are needed.     

一种基于多智能体强化学习的流量分配算法

传统的流量工程策略的研究大多集中在构建和求解数学模型方面,其计算复杂度过高,为此,提出了一种经验驱动的基于多智能体强化学习的流量分配算法.该算法无需求解复杂数学模型即可在预计算的路径上进行有效的流量分配,从而高效且充分地利用网络资源.算法在软件定义网络控制器上进行集中训练,且在训练完成后再接入交换机或者路由器上分布式执行,同时也避免和控制器的频繁交互.实验结果表明,相对于最短路径和等价多路径算法,新算法有效减少了网络的端到端时延,并且增大了网络吞吐量.