基于区域划分和余弦定理的DV-Hop算法改进

针对传统距离向量-跳段定位算法(Distance Vector-Hop,DV-HOP)存在的节点密度分布不均引起误差比较大的问题,根据DV-Hop算法特性,采用余弦定理,证明节点密度越大所得定位坐标越准确,使用余弦定理减少在节点密度过大时因空间角度导致节点路径曲折过多而引起的误差,同时提出一种区域划分的改进算法,减少在节点密度较小区域的误差;利用接收信号强度指示(Received Signal Strength Indicator,RSSI)对跳数进行量化分级处理,改善实际距离与计算出的距离相差过大的情况;最后采用最小二乘法估计未知节点坐标。仿真表明,所提出的算法与传统的DV-Hop算法相比,误差有一定的减少。     

Bayes Theorem Based Virtual Machine Scheduling for Optimal Energy Consumption

This paper proposes an algorithm for scheduling Virtual Machines (VM) with energy saving strategies in the physical servers of cloud data centers. Energy saving strategy along with a solution for productive resource utilization for VM deployment in cloud data centers is modeled by a combination of “Virtual Machine Scheduling using Bayes Theorem” algorithm (VMSBT) and Virtual Machine Migration (VMMIG) algorithm. It is shown that the overall data center’s consumption of energy is minimized with a combination of VMSBT algorithm and Virtual Machine Migration (VMMIG) algorithm. Virtual machine migration between the active physical servers in the data center is carried out at periodical intervals as and when a physical server is identified to be under-utilized. In VM scheduling, the optimal data centers are clustered using Bayes Theorem and VMs are scheduled to appropriate data center using the selection policy that identifies the cluster with lesser energy consumption. Clustering using Bayes rule minimizes the number of server choices for the selection policy. Application of Bayes theorem in clustering has enabled the proposed VMSBT algorithm to schedule the virtual machines on to the physical server with minimal execution time. The proposed algorithm is compared with other energy aware VM allocations algorithms viz. “Ant-Colony” optimization-based (ACO) allocation scheme and “min-min” scheduling algorithm. The experimental simulation results prove that the proposed combination of ‘VMSBT’ and ‘VMMIG’ algorithm outperforms other two strategies and is highly effective in scheduling VMs with reduced energy consumption by utilizing the existing resources productively and by minimizing the number of active servers at any given point of time.     

Efficient conditional probability theorem and importance sampling-based methods for global reliability sensitivity analysis

Global reliability sensitivity (GRS) analysis can measure the effect of random inputs on failure probability (FP). To efficiently solve GRS, two conditional probability theorem (CPT)-based methods are proposed by combining adaptive Kriging (AK) with importance sampling (IS) (CPT-AK-IS) and combining AK with Meta-IS (CPT-AK-Meta-IS) respectively. Firstly, differentiation approximation and CPT are used to convert the estimation of conditional probability density function (PDF), which is required by the existing Bayes theorem-based methods, into that of a series of probabilities. Secondly, GRS can be directly estimated by the failure samples of IS, while the existing Bayes theorem methods based on IS need to transform the failure samples of IS into those of original PDF. Both the first and second strategies can reduce the computational complexity of solving GRS. Thirdly, by selecting a suitable differentiation interval with a proposed adaptive strategy, the estimation of a series of probabilities can be accurately completed as a byproduct of one IS based simulation for solving FP without additional computational cost. Finally, by introducing AK into IS and Meta-IS, it can reduce the number of evaluating performance function and the size of candidate sample pool simultaneously. These novelties are sufficiently verified by the presented examples.     

Dynamical responses for a vertical vibration model of a four-roller cold rolling mill under combined stochastic and harmonic excitations

Considering that random fluctuations can affect the rolling process of cold rolling mills, leading to abnormal cold mill performance and defects in the rolled product. Therefore, it is crucial to study the influence of random fluctuations on the system of cold rolling mills. In this paper, taking a model of the vertical vibration of a four-roller cold rolling mill under harmonic excitation as a prototype class for a real system, the effects of random fluctuations on the system response are analyzed. Firstly, based on the deterministic vertical vibration model of a four-roller cold rolling mill under harmonic excitation, a stochastic vertical vibration model of a four-roller cold rolling mill with random fluctuation as Gaussian white noise is introduced. Subsequently, the vertical vibration model of a four-roller rolling mill is theoretically analyzed by the averaging method and the stochastic averaging method, respectively. The effectiveness of the proposed theoretical method is verified by numerical simulation results, and the influences of harmonic excitation and random excitation on the system response are also investigated in detail. Finally, the results show that the noise induces the occurrence of stochastic transitions and bifurcations, and the steady-state probability density function and time history diagrams are given to further explain the existence of these dynamic phenomena. The related research can provide theoretical guidance for the realization of vibration control and reliability design in the four-roller cold rolling mill system.     

双枝模糊集(Ⅲ)

提出双枝模糊集Ｓ的理论,本课题是［Ⅰ,Ⅱ］研究的继续．在单枝模糊集理论（Ｌ．Ａ．ＺａｄｅｈＦｕｚｚｙＳｅｔＴｈｅｏｒｙ）研究中,由于引进λ－截集Ｓλ的概念,便产生了单枝模糊集的并－普通分解定理［３］,交－普通分解定理［４］．［Ⅰ,Ⅱ］提出了双枝模糊集Ｓ,由于引进了λ－截集Ｓλ的概念,便产生了双枝模糊集Ｓ的并－普通分解定理,交－普通分解定理．人们自然提出这样的问题：双枝模糊集可以分解成若干个普通集Ｓλ;双枝模糊集Ｓ是否能分解成若干个模糊集Ｓα？本文的研究说明：双枝模糊集Ｓ可以分解成若干个模糊集Ｓα．（一个单枝模糊集Ａ也可以分解成若干个模糊集Ａα,但是在单枝模糊集理论中没有被人们去研究．）本文给出Ｓ的α－嵌入集Ｓα的概念,提出Ｓ的α－嵌入定理,Ｓ的α－嵌入模糊分解定理．     

双枝模糊集(Ⅱ)

提出双枝模糊集Ｓ的理论,是（Ｉ）研究的继续．提出双枝模糊集Ｓ的并－普通分解定理,交－普通分解定理．这些结论建立了双枝模糊集Ｓ与普通集Ｓλ之间的关系,这些结论为建立双枝模糊推理,双枝模糊控制作了理论准备．结论指出：（１）双枝模糊集Ｓ同时存在并－普通分解形式：Ｓ＝∪λ∈［－１,１］λＳλ和交－普通分解形式：Ｓ＝∩λ∈［－１,１］λＳλ;这两种分解形式是建立双枝模糊推理理论,双枝模糊控制理论的理论基础．（２）单枝模糊集Ａ（Ｌ．Ａ．ＺａｄｅｈＦｕｚｚｙＳｅｔＡ）的并－普通分解定理,交－普通分解定理是双枝模糊集Ｓ的并－普通分解定理,交－普通分解定理的特例．     

Stochastic source seeking for nonholonomic unicycle

We apply the recently introduced method of stochastic extremum seeking to navigate a nonholonomic unicycle towards the maximum of an unknown, spatially distributed signal field, using only the measurement of the signal at the vehicle’s location but without the measurement of the vehicle’s position. Keeping the forward velocity constant and controlling only the angular velocity, we design a stochastic source seeking control law which employs excitation based on filtered white noise, rather than sinusoidal perturbations used in the existing work. We study stability with the help of stochastic averaging theorems that we recently developed for general nonlinear continuous-time systems with stochastic perturbations. We prove local exponential convergence, both almost surely and in probability, to a small neighborhood near the source. We characterize the convergence speed explicitly and provide design guidelines for maximizing it, as well as for minimizing the residual set near the source. We present a detailed simulation study, including a study of the effect of saturation on the steering input.     

Root-restricted Kleenean rotations

We generalize the Kleene theorem to the case where nonassociative products are used. For this purpose, we apply rotations restricted to the root of binary trees.     

Adaptive discrete neural observer design for nonlinear systems with unknown time‐delay

This paper focuses on the adaptive observer design for nonlinear discrete‐time MIMO systems with unknown time‐delay and nonlinear dynamics. The delayed states involved in the system are arguments of a nonlinear function and only the estimated delay is utilized. By constructing an appropriate Lyapunov–Krasovskii function, the delay estimation error is considered in the observer parameter design. The proposed method is then extended to the system with a nonlinear output measurement equation and the delayed dynamics. With the help of a high‐order neural network (HONN), the requirement for a precise system model, the linear‐in‐the‐parameters (LIP) assumption of the delayed states, the Lipschitz or norm‐boundedness assumption of unknown nonlinearities are removed. A novel converse Lyapunov technical lemma is also developed and used to prove the uniform ultimate boundedness of the proposed observer. The effectiveness of the proposed results is verified by simulations. Copyright © 2010 John Wiley & Sons, Ltd.