An experimental model of relay deployment planning tool for a wireless sensor network system to monitor civil engineering structures

It is essential to monitor deteriorated civil engineering structures cautiously to detect symptoms of their serious disruptions. A wireless sensor network can be an effective system for monitoring civil engineering structures. It is fast to deploy sensors especially in difficult-to-access areas, and it is extendable without any cable extensions. Since our target is to monitor deteriorations of civil engineering structures such as cracks at tunnel linings, most of the locations of sensors are known, and sensors are not required to move dynamically. Therefore, we focus on developing a deployment plan of a static network in order to reduce the value of a cost function such as initial installation cost and summation of communication distances of the network. The key issue of the deployment is the location of relays that forward sensing data from sensors to a data collection device called a gateway. In this paper, we propose a relay deployment-planning tool that can be used to design a wireless sensor network for monitoring civil engineering structures. For the planning tool, we formalize the model and implement a local search based algorithm to find a quasi-optimal solution. Our solution guarantees two routings from a sensor to a gateway, which can provide higher reliability of the network. We also show the application of our experimental tool to the actual environment in the London Underground.

Short- and long-term changes in joint co-contraction associated with motor learning as revealed from surface EMG.

In the field of motor control, two hypotheses have been controversial: whether the brain acquires internal models that generate accurate motor commands, or whether the brain avoids this by using the viscoelasticity of musculoskeletal system. Recent observations on relatively low stiffness during trained movements support the existence of internal models. However, no study has revealed the decrease in viscoelasticity associated with learning that would imply improvement of internal models as well as synergy between the two hypothetical mechanisms. Previously observed decreases in electromyogram (EMG) might have other explanations, such as trajectory modifications that reduce joint torques. To circumvent such complications, we required strict trajectory control and examined only successful trials having identical trajectory and torque profiles. Subjects were asked to perform a hand movement in unison with a target moving along a specified and unusual trajectory, with shoulder and elbow in the horizontal plane at the shoulder level. To evaluate joint viscoelasticity during the learning of this movement, we proposed an index of muscle co-contraction around the joint (IMCJ). The IMCJ was defined as the summation of the absolute values of antagonistic muscle torques around the joint and computed from the linear relation between surface EMG and joint torque. The IMCJ during isometric contraction, as well as during movements, was confirmed to correlate well with joint stiffness estimated using the conventional method, i.e., applying mechanical perturbations. Accordingly, the IMCJ during the learning of the movement was computed for each joint of each trial using estimated EMG-torque relationship. At the same time, the performance error for each trial was specified as the root mean square of the distance between the target and hand at each time step over the entire trajectory. The time-series data of IMCJ and performance error were decomposed into long-term components that showed decreases in IMCJ in accordance with learning with little change in the trajectory and short-term interactions between the IMCJ and performance error. A cross-correlation analysis and impulse responses both suggested that higher IMCJs follow poor performances, and lower IMCJs follow good performances within a few successive trials. Our results support the hypothesis that viscoelasticity contributes more when internal models are inaccurate, while internal models contribute more after the completion of learning. It is demonstrated that the CNS regulates viscoelasticity on a short- and long-term basis depending on performance error and finally acquires smooth and accurate movements while maintaining stability during the entire learning process.

在体大鼠海马区侧枝联合纤维通路和TA通路的不同空间整合特性

在麻醉Wistar大鼠上,结合脑室给药,应用双电极刺激技术刺激海马独立的两条侧枝／联合纤维通 路、TA通路,并在CAl区放射层记录兴奋性突触后电位(EPSP),对海马CAl区锥体细胞近、远端树突EPSP 的空间整合进行了初步探讨。结果表明,海马CAl区锥体细胞近、远端树突的空间整合都是亚线性的;近端树 突的空间整合不受期望值大小的影响,但远端树突的空间整合随期望值增加而减小(更趋于亚线性)。此外, 荷包牡丹碱没有影响EPSP的空间整合;但瞬时A型钾通道(IAK+)的拮抗剂氨基吡啶-4却使得近端树突的 空间整合趋于线性发展。本研究表明,海马CAl锥体细胞近、远端树突不同的被动、主动特征使它们具有了不 同的空间整合特性。由于近端树突接受海马内部侧枝／联合纤维投射的信息,远端树突通过TA通路接受内嗅皮 层投射的信息,由此提示,CAl区锥体细胞对来自海马内部和直接来自皮层的信息输入采用了不同的整合方 式。

Task-dependent coordination of rapid bimanual motor responses.

Optimal feedback control postulates that feedback responses depend on the task relevance of any perturbations. We test this prediction in a bimanual task, conceptually similar to balancing a laden tray, in which each hand could be perturbed up or down. Single-limb mechanical perturbations produced long-latency reflex responses ("rapid motor responses") in the contralateral limb of appropriate direction and magnitude to maintain the tray horizontal. During bimanual perturbations, rapid motor responses modulated appropriately depending on the extent to which perturbations affected tray orientation. Specifically, despite receiving the same mechanical perturbation causing muscle stretch, the strongest responses were produced when the contralateral arm was perturbed in the opposite direction (large tray tilt) rather than in the same direction or not perturbed at all. Rapid responses from shortening extensors depended on a nonlinear summation of the sensory information from the arms, with the response to a bimanual same-direction perturbation (orientation maintained) being less than the sum of the component unimanual perturbations (task relevant). We conclude that task-dependent tuning of reflexes can be modulated online within a single trial based on a complex interaction across the arms.

A computer algorithm for determining the tensile strength of float glass

The extrinsic tensile strength of glass can be determined explicitly if the characteristics of the critical surface flaw are known, or stochastically if the critical flaw characteristics are unknown. This paper makes contributions to both these approaches. Firstly it presents a unified model for determining the strength of glass explicitly, by accounting for both the inert strength limit and the sub-critical crack growth threshold. Secondly, it describes and illustrates the use of a numerical algorithm, based on the stochastic approach, that computes the characteristic tensile strength of float glass by piecewise summation of the surface stresses. The experimental validation and sensitivity analysis reported in this paper show that the proposed computer algorithm provides an accurate and efficient means of determining the characteristic strength of float glass. The algorithm is particularly useful for annealed and thermally treated float glass used in the construction industry. © 2012 Elsevier Ltd.

ChESS - Quick and Robust Detection of Chess-board Features

Localization of chess-board vertices is a common task in computer vision, underpinning many applications, but relatively little work focusses on designing a specific feature detector that is fast, accurate and robust. In this paper the `Chess-board Extraction by Subtraction and Summation' (ChESS) feature detector, designed to exclusively respond to chess-board vertices, is presented. The method proposed is robust against noise, poor lighting and poor contrast, requires no prior knowledge of the extent of the chess-board pattern, is computationally very efficient, and provides a strength measure of detected features. Such a detector has significant application both in the key field of camera calibration, as well as in Structured Light 3D reconstruction. Evidence is presented showing its robustness, accuracy, and efficiency in comparison to other commonly used detectors both under simulation and in experimental 3D reconstruction of flat plate and cylindrical objects

ChESS - Quick and robust detection of chess-board features

Localization of chess-board vertices is a common task in computer vision, underpinning many applications, but relatively little work focusses on designing a specific feature detector that is fast, accurate and robust. In this paper the 'Chess-board Extraction by Subtraction and Summation' (ChESS) feature detector, designed to exclusively respond to chess-board vertices, is presented. The method proposed is robust against noise, poor lighting and poor contrast, requires no prior knowledge of the extent of the chess-board pattern, is computationally very efficient, and provides a strength measure of detected features. Such a detector has significant application both in the key field of camera calibration, as well as in structured light 3D reconstruction. Evidence is presented showing its superior robustness, accuracy, and efficiency in comparison to other commonly used detectors, including Harris & Stephens and SUSAN, both under simulation and in experimental 3D reconstruction of flat plate and cylindrical objects. © 2013 Elsevier Inc. All rights reserved.

Reducing organic substances from anaerobic decomposition of hydrophytes

Oxidation-reduction properties of surface sediments are tightly associated with the geochemistry of substances, and reducing organic substances (ROS) from hydrophytes residues may play an important role in these processes. In this study, composition, dynamics, and properties of ROS from anaerobic decomposition of Eichhornia crassipes (Mart.) Solms, Potamogenton crispus Linn, Vallisneria natans (Lour.) Hara, Lemna trisulca Linn and Microcystis flos-aquae (Wittr) Kirch were investigated using differential pulse voltammetry (DPV). The type of hydrophytes determined both the reducibility and composition of ROS. At the peak time of ROS production, the anaerobic decomposition of M. flos-aquae produced 6 types of ROS, among which 3 belonged to strongly reducing organic substance (SROS), whereas there were only 3-4 types of ROS from the other hydrophytes, 2 of them exhibiting strong reducibility. The order of potential of hydrophytes to produce ROS was estimated to be: M. flos-aquae > E. crassipes > L. trisulca > P. crispus approximate to V. natans, based on the summation of SROS and weakly reducing organic substances (WROS). The dynamic pattern of SROS production was greatly different from WROS. The total SROS appeared periodic fluctuation with reducibility gradually weakening with incubation time, whereas the total WROS increased with incubation time. Reducibility of ROS from hydrophytes was readily affected by acid, base and ligands, suggesting that their properties were related to these aspects. In addition to the reducibility, we believe that more attention should be paid to the other behaviors of ROS in surface sediments.

求和生成器的相关性分析

J.Dj,Golic运用线性序列电路逼进的方法来分析具有任意个输入的求和生成器,他猜想可以通过这种方法来获得所有具有最大相关系数的输入和输出线性函数对,但是他未给出证明。利用Walsh变换技术证明了当n是偶数的时候这个猜想成立。另外,还研究了求和生成器的相关系数总和,发现它与带1比特组合器的相关系数总和非常类似。

Two-photon asymmetric color-locking second-order stochastic correlation of attosecond polarization beats

Based on the phase-conjugation polarization interference between two two-photon processes, we theoretically investigated the attosecond scale asymmetry sum-frequency polarization beat in four-level system (FASPB). The field correlation has weak influence on the FASPB signal when the laser has narrow bandwidth. Conversely, when the laser has broadband linewidth, the FASPB signal shows resonance-nonresonance cross correlation. The two-photon signal exhibits hybrid radiation-matter detuning terahertz; damping oscillation, i.e., when the laser frequency is off resonance from the two-photon transition, the signal exhibits damping oscillation and the profile of the two-photon self-correlation signal also exhibits zero time-delay asymmetry of the maxima. We have also investigated the asymmetry of attosecond polarization beat caused by the shift of the two-photon self-correlation zero time-delay phenomenon, in which the maxima of the two two-photon signals are shifted from zero time-delay point to opposite directions. As an attosecond ultrafast modulation process, FASPB can be intrinsically extended to any level-summation systems of two dipolar forbidden excited states.

Optical image processing using the photoinduced anisotropy of pyrrylfulgide

A synthesized photochromic compound-pyrrylfulgide-is prepared as a thin film doped in a polymethylmethacrylate (PMMA) matrix. Under irradiation by UV light, the film converts from the bleached state into a colored state that has a maximum absorption at 635 nm and is thermally stable at room temperature. When the colored state is irradiated by a linearly polarized 650 nm laser, the film returns to the bleached state; photoinduced anisotropy is produced during this process. Application of optical image processing methods using the photoinduced anisotropy of the pyrrylfulgide/PMMA film is described. Examples in non-Fourier optical image processing, such as contrast reversal and image subtraction and summation, as well as in Fourier optical image processing, such as low-pass filtering and edge enhancement, are presented. (c) 2006 Optical Society of America.

2-DELTA-FUNCTION GENERALIZED PLASMA POLE MODEL FOR 1ST PRINCIPLE CALCULATIONS OF QUASI-PARTICLE ENERGIES IN MANY-ELECTRON SYSTEMS

To evaluate the dynamical effects of the screened interaction in the calculations of quasiparticle energies in many-electron systems a two-delta-function generalized plasma pole model (GPP) is introduced to simulate the dynamical dielectric function. The usual single delta-function GPP model has the drawback of over simplifications and for the crystals without the center of symmetry is inappropriate to describe the finite frequency behavior for dielectric function matrices. The discrete frequency summation method requires too much computation to achieve converged results since ab initio calculations of dielectric function matrices are to be carried out for many different frequencies. The two-delta GPP model is an optimization of the two approaches. We analyze the two-delta GPP model and propose a method to determine from the first principle calculations the amplitudes and effective frequencies of these delta-functions. Analytical solutions are found for the second order equations for the parameter matrices entering the model. This enables realistic applications of the method to the first principle quasiparticle calculations and makes the calculations truly adjustable parameter free.

植被保持水土的基本规律和总结

在多年研究工作的基础上 ,全面阐述了植被保持水土的基本特征和规律 ,并对其进行了系统研究总结 ,为客观分析和评价植被的作用和效果 ,以及正确制定和实施水土保持方针和政策提供了科学依据。

基于参数化求和不变量与特征重整的形状匹配

从特征提取和特征匹配两方面考虑,提出了一种鲁棒的形状匹配方法。首先,基于求和不变量,设计了基于面积的形状参数化和归一化方法,提出了参数化求和不变量,该不变量基于形状局部描述且采用积分算子计算,具有较好的鲁棒性和仿射不变性。然后,为进一步提高形状匹配的鲁棒性,在特征匹配上,分析了参数化求和不变量的先验信息,设计了基于特征重整的匹配距离函数,并通过动态规划进行实现。仿真实验表明了所提方法的有效性。

地震采集观测系统的共聚焦分析

Focal beam analysis is a method for assessment of acquisition geometries that is directly linked to pre-stack migration. About dealing with the complex subsurface structures, the conventional survey design methods which do not take into account the subsurface are no longer valid. Based on the Fourier finite-difference (FFD) large-step wave field extrapolation and Born-Kirchhoff (BK) small-step wavefield interpolation, the thesis presents a rapid resolution analysis of 3D seismic survey design by focal beams in complicated media. Subsequently, The SEG/EAEG salt model is used to illustrate the method. Based on the focal beam resolution definition, each kind of influence factor is discussed. The focal beam analysis usually is carried out in a single frequency, but the actual seismic waves always contain a frequency bandwidth. In this thesis, theoretical relationship between focal beam analysis and frequency is derived. Since the effects of focal beam analysis are linear with frequency simply, the multi-frequency focal beam analysis using interpolation is developed. At the same time, the resolution of different frequency bandwidth is interconvertible in accordance with Signal uncertainty principle. The resolution of all frequency bands can be calculated by using only a few focal beam analysis for a seismic survey. In the last section of this thesis, I propose a new approach to predicting acquisition footprint, based on the assumption of Common-Middle-Point stack without constructing a special velocity model. The approach is a simplistic analytical method in which the acquisition footprint pattern is a weighted, linear summation of limited-offset fold-of-stack plots. Because the value of acquisition can be got by quantificational and rapidly calculating, we can exactly do a comparative analysis among different plans of seismic survey by this method.