基于模糊距离和DS证据融合的清洁机器人定位设计

针对现有清洁机器人定位算法具有的定位精度不高且难以保证在线定位的实时性问题,设计了一种基于模糊距离和DS(DEMPSTER-SHAFER)证据融合的清洁机器人自定位算法。首先,对清洁机器人的总体结构进行了建模和分析,并对其进行硬件设计,为了实现清洁机器人的实时精确定位,采用DS证据数据融合方法对多传感器采集的数据进行有效数据融合,为了进一步提高其精确性,引入了模糊距离,定义当前传感器采集数据与理想结果之间的距离,根据距模糊距离的大小自适应地调大或减少传感器采集数据分配信度的权重,将加权信度作为新的信度进行融合得到最终的融合结果。在不同的场地中进行实际试验,对文中设计的清洁机器人进行实际定位,实验结果表明文中方法能有效地进行定位,较经典的DS证据融合和其它方法具有较高的定位精度,且具有较小的时间复杂度和空间复杂度, 具有较大的优越性。     

Microcrack interaction brittle rock subjected to uniaxial tensile loads

A micromechanics-based model is proposed to describe unstable damage evolution in microcrack-weakened brittle rock material. The influence of all microcracks with different sizes and orientations are introduced into the constitutive relation by using the statistical average method. Effects of microcrack interaction on the complete stress–strain relation as well as the localization of damage for microcrack-weakened brittle rock material are analyzed by using effective medium method. Each microcrack is assumed to be embedded in an approximate effective medium that is weakened by uniformly distributed microcracks of the statistically-averaged length depending on the actual damage state. The elastic moduli of the approximate effective medium can be determined by using the dilute distribution method. Micromechanical kinetic equations for stable and unstable growth characterizing the ‘process domains’ of active microcracks are taken into account. These ‘process domains’ together with ‘open microcrack domains’ completely determine the integration domains of ensemble averaged constitutive equations relating macro-strain and macro-stress. Theoretical predictions have shown to be consistent with the experimental results.     

On localization modes in coupled thermo-hydro-mechanical problems

A perturbation approach is used to study localization phenomena in saturated porous media when thermo-mechanical loadings and thermo-hydro-mechanical couplings are fully taken into account. We show that various types of localization modes are possible depending on the constitutive behavior and loading conditions. Examination of the associated conditions in the light of the classical band approach reveals that the differences between these modes lie in their structure which may involve jumps in different variables (beside the velocity gradient) such as the gradients of heat and fluid fluxes, the temperature and the pressure rates. To cite this article: A. Benallal, C. R. Mecanique 333 (2005).     

Localization on Quantum Graphs with Random Vertex Couplings

We consider Schrödinger operators on a class of periodic quantum graphs with randomly distributed Kirchhoff coupling constants at all vertices. We obtain necessary conditions for localization on quantum graphs in terms of finite volume criteria for some energy-dependent discrete Hamiltonians. These conditions hold in the strong disorder limit and at the spectral edges.     

Glassy dynamics in strongly anharmonic chains of oscillators

We review the mechanism for transport in strongly anharmonic chains of oscillators near the atomic limit where all oscillators are decoupled. In this regime, the motion of most oscillators remains close to integrable, i.e. quasi-periodic, on very long time scales, while a few chaotic spots move very slowly and redistribute the energy across the system. The material acquires several characteristic properties of dynamical glasses: intermittency, jamming, and a drastic reduction of the mobility as a function of the thermodynamical parameters. We consider both classical and quantum systems, though with more emphasis on the former, and we discuss also the connections with quenched disordered systems, which display a similar physics to a large extent.     

On the nonlinear interactions and existence of breathers in a chain of coupled pendulums

The paper considers a chain of linearly coupled pendulums. Continues first order system equations are treated via time and space multiple scale method which lead to nonlinear Schrödinger equation. Further investigations on the nonlinear Schrödinger equation detects systems responses in the form of propagated nonlinear waves as functions of their envelope and phases. This provides information about localization of nonlinear waves and their directions in space and time.     

Prediction of interface states in liquid surface waves with one-dimensional modulation

We theoretically study the interface states of liquid surface waves propagating over the heterojunctions formed by a bottom with one-dimensional periodic undulations. By considering the periodic structure as a homogeneous one, our systematic study shows that the signs of the effective depth and gravitational acceleration are opposite within the band gaps whether the structure is symmetric or not. Those effective parameters can be used to predict the interface states which could amplify the amplitudes of liquid surface waves. These phenomena provide new opportunities to control the localization of water-wave energy.     

A Spherical Band-based DV-Hop localization technique for three-dimensional wireless sensor network

Wireless Sensor Networks have been the focal point of research for many years due to their wide range of application areas. Such networks consist of resource-constrained sensor nodes that are generally not equipped with any positioning component due to cost issues. This requires the adoption of suitable methodologies to infer the location of the deployed sensor nodes. Location information of such sensor nodes can be obtained with the help of some location-aware nodes. Numerous localization algorithms exist in the literature. Amongst them, Distance Vector Hop (DV-Hop) is a computationally less expensive algorithm that uses hop count values between sensor nodes and anchor nodes for location estimation of the deployed sensor nodes. However, the traditional DV-Hop algorithm produces a larger positioning deviation for a higher hop count value. Several existing works attempt to address this issue by either modifying the hop size or optimizing the estimated position resulting in comparatively higher localization errors and computationally expensive. This paper aims to solve the issue by modifying the hop size by dividing it into equal-sized spherical bands (SB). Sensor nodes use this SB value for computing their distances from anchor nodes and non-coplanar anchor nodes for location estimation. The simulation results demonstrate that the mean localization error of the proposed approach has reduced approximately by 75%, 66%, and 47% in comparison to traditional DV-Hop, 3D PSODV-Hop, and 3D GAIDV-Hop respectively.