一种基于触发机制的轮转算法

在负载平衡技术中,必须使用合适的算法进行成员选择,以决定由哪个副本对象处理到来的客户请求。传统轮转负载平衡算法只能在某些特定条件下平衡负载。针对该缺点,结合普通轮转算法和加权算法的优点,提出一种基于触发机制的轮转算法。实验结果表明,该算法能感知后段资源。     

Constant round group key agreement protocols: A comparative study

The scope of this paper is to review and evaluate all constant round Group Key Agreement (GKA) protocols proposed so far in the literature. We have gathered all GKA protocols that require 1,2,3,4 and 5 rounds and examined their efficiency. In particular, we calculated each protocol’s computation and communication complexity and using proper assessments we compared their total energy cost. The evaluation of all protocols, interesting on its own, can also serve as a reference point for future works and contribute to the establishment of new, more efficient constant round protocols.     

以太网基于优先级的流控仿真设计

互联网在飞速发展的同时,也给网络系统的正常运行带来了一系列的问题,其中最突出的是由网络流量过大引起的网络拥塞。通过对多种流控方法的研究,最终从队列调度方面着手,利用OPNET网络仿真软件对所设计的三种流控机制进行仿真,初步解决了以太网较高优先级的数据流无法得到及时响应的问题以及公平性问题。     

Optimization of oval–round pass design using genetic algorithm

The primary purpose of this paper is to propose a computer aided optimal design system to support a generalized oval–round pass design, which is widely used as both intermediate and final passes in the process of rod rolling. This system, which is based on a hybrid model and the genetic algorithm, is developed to improve the efficiency, to reduce the manufacturing errors, as well as to extend the useful life of rolls through uniform wear design. Generalized parametric equations are established for geometrical modeling, graphic plotting of oval–round passes, as well as calculation of the cross section area, contact area and the lengths of contact arcs along the cross section of round groove in the MATLAB programming environment. Moreover, these equations can also realize the parametric transformation between roll profile and mathematical models for the oval–round pass design and optimization. The genetic algorithm is employed for the optimal design of oval–round passes in this paper. The objective functions are formulated for minimization of power consumption in the rolling process, variances between ideal dimensions and design dimensions, as well as variances between the lengths of contact arcs. To reduce the complexity and computational burden of the system, some reliable empirical formulas for the calculations of contact area and contact arc length are applied. Finally, the proposed approach is applied to an oval–round pass design. Through simulation and comparison of results against experimental data acquired from literature, it is found that this system is reliable, effective and easier to use.     

Designing against a class of algebraic attacks on symmetric block ciphers

Recently, Courtois and Pieprzyk proposed a class of algebraic attacks on symmetric block ciphers that takes advantage of a previously-unexploited property of substitution boxes, or s-boxes, in the round function. This paper gives a brief overview of this ``overdefined system of equations' (OSE) attack and shows how the attack may be avoided through the use of round functions constructed according to the CAST design procedure. Such round functions contain a variety of protection mechanisms, including s-boxes of large dimension, a circular key-dependent rotation step, and combinations of operators from different algebraic groups.     

双（多）基地声纳浮标系统在反潜中的应用研究

在双基地声纳系统中，根据能量关系推导出双基地声纳系统最大可探测范围的数学模型；在此基础上，讨论了用双（多）基地声纳浮标系统布放直线阵、圆形阵时的阵形宽度、搜索面积及所需浮标数，并将之与传统被动浮标阵进行了比较．结果表明：采用双（多）基地浮标阵可以在一定程度上节省浮标数，提高了浮标的使用效率．     

移动IP环境下的平滑切换缓存管理优化

为克服移动节点在移动切换过程中丢包并使服务质量达到无缝切换的效果，IETF提出了平滑切换的解决方案．但此方案在实际应用中易造成整个网络吞吐率的下降．本文在通过仿真实验验证IETF缓存管理机制对TCP网络的性能造成影响的基础上，提出了一种基于RTT的拥塞窗口控制方案，仿真实验结果显示该方案能很好地解决平滑切换过程所造成的网络性能下降问题，具有其合理性与实用性．     

连铸圆坯质量缺陷评述

评述了连铸圆坯常见的质量缺陷类型、成因及改善质量的相关措施.     

全面预算在企业管理中的实施

本文主要从全面预算的角色定位、预算的目标导向、预算、核算与考核同步协调、预算管理的预警机制等方面对预算管理进行阐述,探讨预算管理对于提升企业管理水平的作用和具体实施办法。     

气割集箱管椭圆端孔的专用装置

为气割椭圆孔 ,采用行星轮装置控制割炬运动轨迹 ,不但提高了加工效率 ,而且提高了非圆气割的形状精度