Vector median filters

Median filters (MF) are used both to filter ‘salt and pepper’ noise from signals and images and in other signal processing applications. In this paper, an extension of the MF, the vector median filter (VMF), is introduced. As opposed to the MF, the VMF outputs for each window location a number of data elements. By adjusting the VMF parameters, the MF is obtained as a VMF special case. Just like the MF, the VMF filters impulses while simultaneously preserving step changes in a signal. The VMF's principal advantage is that it reduces the total stored data signal computation time while it produces visual outputs comparable to that of an MF. Deterministic and statistical properties of the VMF are examined. Computer-generated experimental results are also presented.     

SNMP在运维系统公交车载终端上的设计和实现研究

针对目前公交车载嵌入式终端存在没有统一网络管理机制的问题,设计了基于公交车载终端的SNMP网络管理代理系统。着重研究和设计了SNMP网管代理系统的软件部分,完成了SNMP网管系统的代码编写和在车载终端上的移植。系统通过分析终端特性和管理参数,采用SNMP消息机制,完成对设备的管理和与管理站的通信,方便对公交车载终端的统一管理,也增强了公交系统的安全性。通过在ZTM2001上部署和测试,验证了设计的可靠性、稳定性和故障检测能力。     

互联网延迟队列解决方案设计

针对互联网中广泛存在的延迟任务处理问题,本文分析了技术难点和常见的解决方案,并基于Redis中间件设计和实现了延迟队列系统.该系统具有轻量级、高可用、低耦合、高性能等特点,能够支撑业务系统的稳定运行.     

多涡卷Jerk混沌吸引子的EWB仿真

混沌吸引子的产生是将混沌信号应用于加密领域的基础。文中在双涡卷Jerk混沌吸引子的基础上,利用阶梯波函数构造产生出多涡卷Jerk混沌吸引子,分析了多涡卷Jerk混沌吸引子的产生机理,并根据无量纲状态方程,分别设计了6-涡卷和7-涡卷混沌吸引子仿真电路。利用EWB电路仿真软件进行了仿真验证,仿真结果与数学分析结果一致,证明了多涡卷Jerk系统的存在。     

Effects of gravity on mechanical properties of GTA welded joints

Stainless steel alloy 316 weld samples were subjected to spot gas tungsten arc welding at 1G (G = 9.8 m/s²) and 3.6G accelerations. The cross sections of the fusion zones were polished, etched, and measured in order to perform measurements on the microstructure. Measurement and observation results indicated that increasing in buoyancy driven flow produced wider but shallower welds during spot GTA welding. Tensile testing showed no noticeable differences in peak loads between samples welded at 1G and 3.6G. Tensile ductility was lightly less for the 3.6G samples.     

Fairness of traffic controls for inelastic flows in the Internet

In best-effort networks, fairness has been used as a criterion to guide the design of traffic controls. The notion of fairness has evolved over time, from simple equality to a form of equality modulated by the user’s need (e.g. max–min and proportional fairness). However, fairness has always been defined on a per-user basis for a deterministic workload. In this paper, we argue that we must redefine the notion of fairness when we study traffic controls for the co-existence of elastic and inelastic traffics. Our results indicate that subjecting inelastic flows to fairness congestion control on a per-flow basis does not necessarily maximize the network’s utility. Instead, inelastic flows may follow their own form of traffic control, such as admission control (without congestion control). At the aggregate level, our results indicate that it still makes sense to maintain a balance between elastic and inelastic traffic. In order to support our arguments, we develop a methodology for comparing different traffic controls for given utility functions and different workloads, both deterministic and stochastic.     

P2P流媒体服务方案及其关键技术研究

根据近年来P2P流媒体服务方案的研究成果,归纳并总结P2P流媒体的关键技术,包括覆盖网络构建技术、数据调度技术以及各种优化技术。由此可知,P2P流媒体是一种性价比高、扩展性好的流媒体服务体系,并指出P2P流媒体可进一步的研究方向为P2P流媒体的应用与测量、理论分析与建模、体系架构以及与视频编码、移动网络技术的结合等。     

一种高效的动态几何图形迭代算法

图形迭代是动态几何软件中的重要功能,分析动态几何中图形迭代的实现原理,设计并实现一种高效的图形迭代算法,以解决原有算法效率低的问题,通过实验比较表明新算法具有良好运行效率。     

一种门限代理签名方案的分析与改进

C-Y Yang等人提出了一个安全性基于求解离散对数困难性的门限代理签名方案,该方案具有较少的通信量及较高的计算效率。基于数论知识分析该方案存在缺陷：不满足不可伪造性和不可否认性,提出了改进方案将代理密钥以门限的方式在成员间共享,使得每个成员的子代理密钥都包含个体随机数,其他成员无法获知某成员的子代理密钥。改进方案的安全性基于求解离散对数的困难性,能抵御密钥替换攻击,具备不可伪造性和不可否认性。     

Synthesis of dodecylbenzene via the alkylation of benzene and 1-dodecene over mesopore Beta zeolites

The alkylation of benzene with long chain α-olefins is a crucial process in the production of fine chemicals, which requires the upgrading from traditional homogeneous catalysis to heterogeneous catalysis involving zeolites. However, the application of zeolite catalysts has been limited by their fast deactivation due to constrained diffusion resulting from the sole micropores. To address this challenge, a desilication and secondary-crystallization strategy has been employed to fabricate hierarchically structured mesoporous Beta zeolites. The resultant mesoporous Beta zeolites demonstrate excellent catalytic activity and stability in the alkylation of benzene with 1-dodecene, arising from the exposed acid sites and enhanced internal diffusion. Importantly, the internal diffusion limitations for these mesopore Beta zeolites are negligible, which significantly extends their lifetime and improves their regeneration performance. To achieve these benefits, the degree of mesopores must be deliberately controlled. Overall, this approach provides a promising solution for achieving efficient and environmentally friendly alkylation processes.