Ad Hoc网络中的区域划分和资源分配问题

建立了Ad Hoc网络中的区域划分和资源分配的模型,重点对网络的最少小区数覆盖、抗毁性、节点分簇等问题进行了研究,并对节能性、通信质量评估进行了初步探讨.     

基于韧性度的低轨卫星通信网络抗毁性度量及优化

低轨卫星通信网络的抗毁性是描述网络安全可靠的有效工具,在网络体系结构设计和路由策略等领域得到了广泛的应用。根据低轨卫星通信网络中卫星在轨道平面内移动,需要不断进行切换的特点,从建立抗毁性测度模型以及网络抗毁性优化两个角度来评估和提高网络抗毁性,提出一种基于韧性度的低轨卫星通信网络抗毁性度量方法。通过对移动模型以及切换模型的结构分析,对每种结构以一定概率出现的低轨卫星通信网络,应用韧性度函数,求得网络在某个时刻及某一段时间段内的抗毁性,并针对切换模型的不足之处进行优化,用赋权韧性度来体现优化的效果,得到了优化后的网络抗毁性。以铱星系统为应用实例进行仿真,结果表明:任意时刻网络的抗毁性跟拓扑结构的韧性度值有关,并且是一种线性关系,即随着韧性度的增加,其抗毁性也增加。通过对铱星通信系统切换模型的优化,网络的抗毁性与平均抗毁性都得到了提升,说明本文所构建模型的有效性和实用性。     

Ad Hoc网络中的区域划分和资源分配问题的研究

针对Ad Hoc网络中的区域划分和资源分配问题,在充分保证不出现通信盲区前提下,分别就有湖泊和无湖泊两种情况建立最优化模型,利用计算机搜索求解得到较为满意的结果;对于网络的抗毁性主要从图论的连通性方面入手,利用最大流量最小割集定理,分别对各划分方式的抗毁性进行讨论,得到Ad Hoc网络的抗毁性较强;通过建立最小最大模型,得到较为节能的区域划分方式及信道安排.     

AD HOC网络中的区域划分和资源分配研究

建立了新的Ad Hoc无线网络的区域划分和资源分配模型,讨论了网络覆盖率和抗毁性.通过构造Voronoi图对平面单连通区域的Ad Hoc网络建立区域划分优化模型;定义了网络抗毁性的评价指标连通率,并通过构造Delaunay三角网的最小生成树和蒙特卡罗实验,取得了较好的抗毁仿真结果.最后结合K-均值分簇和罚函数法,得到了近似最优的平面复连通区域的Ad Hoc网络的区域划分和信道安排.     

城市公共交通复合系统抗毁性仿真研究

运用复杂网络理论,对以成都市为例的城市公共交通复合系统网络以及两子系统网络进行了相关拓扑特性与抗毁性分析。分析结果显示,以成都市为例的地铁-公交复合网络及其子网络均为具有无标度特性的小世界网络,在L、P两种空间中均表现出随机袭击下的鲁棒性与蓄意袭击下的脆弱性,且节点的抗毁性低于边的抗毁性;同时在相同袭击条件下,复合网络的抗毁性均优于地铁子网络与地面公交子网络。     

完全κ叉树的离散数和完整度

图的离散数和完整度是比较理想的刻画网络抗毁性的度量参数,而完全k叉树作为重要的网络结构被广泛地应用在通信网和嵌入式系统芯片的优化设计方面.通过界定了完全k叉树的离散数和完整度,从某种程度刻画了网络的抗毁性,为网络设计提供理论依据,同时修正了相关文献的错误.     

圆内两随机点距离的概率分布

研究了圆内两个均匀分布随机点之间距离的概率分布.利用几何概率推导出了概率分布函数、概率密度函数和数学期望的解析表达式.基于R语言,对单位圆内随机点之间距离进行了随机模拟,模拟结果与理论分析结果互为印证.     

代数不等式的概率证明方法

本文讨论了三种概率性质在代数不等式证明中的应用，阐述了如何针对不等式的特点构造随机事件和随机变量，运用概率强可加性、方差非负性、期望线性性质进行不等式证明，同时结合实例展示了证明过程和技巧.     

变系数混合效应模型

本文研究了下列变系数混合效应模型: $y_{ij}=z_{ij}^{\tau}b_i+x_{ij}^{\tau}\beta(w_{ij}) +\xe_{ij},\;i=1,\cdots,m;\;j=1,\cdots,n_i$, 其中$b_i$为i.i.d.期望为$\xt$, 协方差阵为$\xs^2_bI_q$的随机效应向量, $\xe_{ij}$是i.i.d.期望为零, 具有有限方差的随机误差. 文中我们不仅给出了函数系数向量$\xb(\cdot)$的局部多项式估计, 同时给出了随机效应期望、方差和随机误差方差的估计, 并给出了这些估计量的渐进正态性和相合性, 研究结果表明了这些估计量的可靠性.     

基于空间压缩和无穷级数的空间碎片碰撞概率快速算法

空间碎片碰撞概率的计算可以转化为2维正态分布概率密度函数(PDF)在圆域内的积分问题,针对以往方法的不足,首先通过空间压缩将不等方差PDF在圆域内的积分化为等方差PDF在椭圆区域内的积分,并将椭圆区域用与其面积相等的圆区域近似,化为等方差PDF在圆域内的积分,对引入的误差进行了讨论.该积分可以表示为首项与递推公式已知的无穷级数形式,可取级数前任意有限项的和作为概率积分的近似,并且给出了截断误差上限的表达式.根据近似结果分析了最大概率的表达式和此时的位置误差参数.以一次实际发生的碰撞为例对该方法进行了验证,并与另外两种进行了比较,结果表明该方法是一种精度高速度快的方法.     

Self-Concordant Barriers for Convex Approximations of Structured Convex Sets

We show how to approximate the feasible region of structured convex optimization problems by a family of convex sets with explicitly given and efficient (if the accuracy of the approximation is moderate) self-concordant barriers. This approach extends the reach of the modern theory of interior-point methods, and lays the foundation for new ways to treat structured convex optimization problems with a very large number of constraints. Moreover, our approach provides a strong connection from the theory of self-concordant barriers to the combinatorial optimization literature on solving packing and covering problems.     

决策模糊集覆盖系数的实用计算方法

研究了经济学中广泛应用的决策模糊理论中模糊集覆盖系数的性质,并据此提出了无须通过繁杂的统计实验就能够计算覆盖系数的实用方法,进而提出了模糊集交并运算算子.用两个算例说明了该方法和算子与实际情形相符,具有可行性.     

Operational readiness and survivability of network systems

A method is developed for obtaining the operational readiness and the survivability of a network in terms of its branches. The procedure is based on graph theory concepts.     

A characterization of signed hypergraphs and its applications to VLSI via minimization and logic synthesis

A recently introduced graph-theoretic notion of signed hypergraph is studied. In particular, a structural characterization of balanced signed hypergraphs is given, and two optimization problems related to the balance property — the maximum balance and the minimum covering problems — are introduced and characterized. It is shown that both problems are NP-complete in general. Applications of the theory of signed hypergraphs to two VLSI optimization problems, namely via minimization and constrained logic encoding, are described.     

Reduction about approximation spaces of covering generalized rough sets

The introduction of covering generalized rough sets has made a substantial contribution to the traditional theory of rough sets. The notion of attribute reduction can be regarded as one of the strongest and most significant results in rough sets. However, the efforts made on attribute reduction of covering generalized rough sets are far from sufficient. In this work, covering reduction is examined and discussed. We initially construct a new reduction theory by redefining the approximation spaces and the reducts of covering generalized rough sets. This theory is applicable to all types of covering generalized rough sets, and generalizes some existing reduction theories. Moreover, the currently insufficient reducts of covering generalized rough sets are improved by the new reduction. We then investigate in detail the procedures to get reducts of a covering. The reduction of a covering also provides a technique for data reduction in data mining.     

The reduction and fusion of fuzzy covering systems based on the evidence theory

This paper studies reduction of a fuzzy covering and fusion of multi-fuzzy covering systems based on the evidence theory and rough set theory. A novel pair of belief and plausibility functions is defined by employing a method of non-classical probability model and the approximation operators of a fuzzy covering. Then we study the reduction of a fuzzy covering based on the functions we presented. In the case of multiple information sources, we present a method of information fusion for multi-fuzzy covering systems, by which objects can be well classified in a fuzzy covering decision system. Finally, by using the method of maximum flow, we discuss under what conditions, fuzzy covering approximation operators can be induced by a fuzzy belief structure.     

Refinable maps in dimension theory

This paper studies properties of refinable maps and contains applications to dimension theory. It is proved that refinable maps between compact Hausdorff spaces preserve covering dimension exactly and do not raise small cohomological dimension with any coefficient group. The notion of a c-refinable map is introduced and is shown to play a comparable role in the setting of normal spaces. For example, c-refinable maps between normal spaces are shown to preserve covering dimension and S-weak infinite-dimensionality. These facts do not hold for refinable maps.     

基于指数标度的G1-概率系数法和熵的需求重要度修正

顾客需求重要度的获取是进行顾客需求综合分析过程的一个重要环节,它的确定对质量屋的优化以及之后的优化决策有着重要的作用.科学准确地计算顾客需求重要度有助于企业有针对性的生产满足顾客需求的产品,从而提高顾客满意度,增强市场竞争力.基于QFD理论,文章从顾客和专家双视角出发收集数据,采用指数标度的G1-概率系数法代替传统的权重概率综合系数法来确定顾客初始需求权重,并结合市场竞争性因素对初始需求权重进行修正,简单准确地确定了顾客需求重要度,并通过IT外包案例验证了该方法的实效性.     

基于正交试验的乘用车运输网络优化方法

在交通部治理公路超限运输的背景下,本文研究了乘用车物流企业多式联运模式下的网络优化问题,以运输网络总成本最小为目标,考虑物流时效、枢纽节点容量及规模经济效应等因素,构建了基于轴辐式理论的运输网络优化模型,提出了混合智能优化算法。针对多参数多水平的寻优问题,对模型的三个关键输入参数,即枢纽节点数量、枢纽节点容量和规模效应折扣系数,引入正交试验方法,降低求解多参数多水平寻优问题的工作量,为确定各参数合理取值提供了新的途径。研究结果表明:枢纽节点容量、折扣系数与枢纽数量三个输入参数对优化结果的影响具有主次顺序,影响程度依次减弱,而且只有枢纽节点容量与折扣系数对乘用车运输网络总效益的影响起显著作用。采用混合轴辐式的网络结构与多式联运的运输组织模式进行优化后的运输网络,相对于原有“点对点”公路运输网络总成本减少10%,从运营管理与成本控制两方面均可有效应对公路治超带来的风险。