基于GIS的滑坡综合预测预报信息系统

由于滑坡的复杂性、随机性和不确定性,加之目前的滑坡灾害预测预报理论研究还存在局限性,大大增加了滑坡预报的难度。本文针对目前滑坡预测预报研究中的不足,提出了滑坡综合预测预报信息系统,并对该系统的结构、功能和内容等进行了详尽地设计和开发。滑坡综合预测预报信息系统以G IS为平台,利用智能决策支持系统的理论和方法将以监测资料为依据的滑坡定量预报与以专家经验知识为依据的滑坡定性预报有机结合起来,做到了各取所长,优势互补,实现了滑坡的综合预测预报,提高了滑坡的预报水平。运用该系统不仅可以判断滑坡体的变形破坏机制、目前的稳定性状况和破坏概率,而且可以对滑坡体的变形演化阶段以及滑动时间作出预测预报,从而给滑坡现场工程师的综合判断和决策提供了重要的参考和有关科学依据的实用化工具。     

环境温度影响下基于LSTM神经网络识别结构损伤

环境温度的改变会引起模态参数的变化,其变化程度会掩盖或部分掩盖损伤引起的变化量,导致结构健康监测系统发出假阳性或假阴性的误判,因此,消除温度效应是提高损伤识别精度的关键。本文基于LSTM神经网络提出了一种环境温度影响下识别结构损伤的方法。充分利用LSTM神经网络的非线性映射优势,建立多元温度-模态频率的相关模型,在此基础上采用数据标准化方法消除温度效应,并结合控制图判断模态频率异常变化以确定损伤状况。最后将所提方法在数值模型和实际桥梁中加以应用,结果表明,方法能够有效消除温度效应;结合控制图能识别损伤时刻,并具有一定的抗噪性;在实桥数据分析中仍能表现出较好的损伤敏感性。     

Thermodynamic coupling in boundary layers by a rapid coupling-factor estimate

Experiments conducted during the last decade show that thermodynamic couplings in boundary layers may result in rather unusual and appreciable changes in the values of heat fluxes in hypersonic flows or even in low-speed flows characterized by large temperature gradients. However, exact estimates of these effects in actual multicomponent boundary-layer flows require mathematical procedures which are too complicated and cumbersome to be of much routine use except in simple binary cases. Unjustifiably these effects have been therefore neglected by most investigators before estimating the expected results under the expected operating conditions. In trying to overcome the aforementioned difficulties we develop a relatively simple new iterative method to obtain rapid approximate estimates of these effects under various operating conditions. The method is amenable to rapid calculations by hand as well as for computer applications and allows also estimates of the particularly interesting coupling effects involved in mass-transfer cooling by foreign gas injection, ablation, evaporation, condensation or suction. By introducing new definitions for coupling factors and equivalent Prandtl and Schmidt numbers for boundary layers the proposed method enables use of simple approximate trial functions to estimate coupling effects by variational or integral analyses. A general variational analysis of velocity, thermal and diffusionalboundary-layer flows which was recently developed by the authors is employed here to illustrate the utility of the method.     

On the effect of particle image intensity and image preprocessing on the depth of correlation in micro-PIV

The depth of correlation (DOC) is an experimental parameter, introduced to quantify the thickness of the measurement volume and thus the depth resolution in microscopic particle image velocimetry (μPIV). The theory developed to estimate the value of the DOC relies on some approximations that are not always verified in actual experiments, such as a single thin-lens optical system. In many practical μPIV experiments, a deviation of the actual DOC from its nominal value can be expected, due for instance to additional components present in the optical path of the microscope or to the use of image preprocessing before the PIV evaluation. In the presented paper, the effect of real particle image intensity distribution and image preprocessing on the thickness of the measurement volume is investigated. This is performed studying the defocusing of tracer particles and the DOC-related bias error present in μPIV measurements in a Poiseuille flow. The analysis shows that the DOC predicted using the conventional formulas can be significantly smaller than its actual value. To overcome this problem, the use of an effective NA determined experimentally from the curvature of the image autocorrelations is proposed. The accuracy of this approach to properly predict the actual size of DOC is discussed and validated on the experimental data. The effectiveness of image preprocessing to reduce the DOC-related bias error is tested and discussed as well.     

Elliptic model for prediction of deflections induced by a Light Falling Weight Deflectometer

The use of a portable lightweight deflectometer for construction quality control and road construction is increasing around the world. However there are some points of weakness that have been poorly investigated in the past. One of them is the definition of the domain of influence of the deflectometer for various test setups and different soils. This paper proposes a new model based on the Boussinesq theory that has been calibrated using the outcome of experimental tests. The series of laboratory and field scale investigations that are presented here are not conventional. In particular the actual deep deflections have been measured under the surface using an original experiments setup. Using the calibrated model, it is also suggested that a revised version of the corrected Boussinesq equation be used to better represent stress distribution in soil, where a second parameter is included along with the so called Froehlich concentration factor.     

Reconstruction of road defects and road roughness classification using Artificial Neural Networks simulation and vehicle dynamic responses: Application to experimental data

This paper reports the performance of an Artificial Neural Network based road condition monitoring methodology on measured data obtained from a Land Rover Defender 110 which was driven over discrete obstacles and Belgian paving. In a previous study it was demonstrated, using data calculated from a numerical model, that the neural network was able to reconstruct road profiles and their associated defects within good levels of fitting accuracy and correlation. A nonlinear autoregressive network with exogenous inputs was trained in a series–parallel framework. When compared to the parallel framework, the series–parallel framework offered the advantage of fast training but had a shortcoming in that it required feed-forward of true road profiles. In this study, the true profiles are not available and the test data are obtained from field measurements. Training data are numerically generated by making minor adjustments to the real measured profiles and applying them to a full vehicle model of the Land Rover. This is done to avoid using the same road profile and acceleration data for training and testing or validating the neural network. A static feed-forward neural network is trained and consequently tested on the real measured data. The results show very good correlations over both the discrete obstacles and the Belgian paving. The random nature of the Belgian paving necessitated correlations to be made using their displacement spectral densities as well as evaluations of RMS error percent values of the raw road profiles. The use of displacement spectral densities is considered to be of much more practical value than the road profiles since they can easily be interpreted into road roughness measures by plotting them over an internationally recognized standard roughness scale.     

A Motorcycle Tire Model for Dynamic Simulations: Theoretical and Experimental Aspects

This paper describes a model for motorcycle tires based on a physical interpretation of experimental data. In this model the real shape of the tire carcass is accurately described and its deformability is taken into account. The actual position of the contact point, that is, the center of the contact patch, is calculated. The concept of instantaneous slip is defined by calculating the longitudinal slip and sideslip angles using the velocity of the actual contact point, which moves with respect to the rim. Tire forces and torques are applied on the actual contact point and calculated according to Pacejkas magic formula. The coupling of sliding properties with elastic ones and the use of the instantaneous slip concept make it possible to properly describe both steady state and transient behavior using the same relations, thus avoiding the use of any auxiliary equations.     

Genetic databases and consent for use of medical records

The legislation on the Icelandic genetic database provides for an opting-out system for the collection of encoded medical information from individual medical records. From the beginning this has raised criticism, in Iceland itself and abroad. The Supreme Court has now decided that this approach of presumed consent is not unconstitutional per se, but that there are not sufficient safeguards to ensure that the information collected is not traceable to individuals. The decision of the court is of importance for the debate (at national and international level) on the legal and ethical aspects of population-based genetic databases. Furthermore, it is interesting because it recognizes the right of close relatives of a deceased person to oppose the collection and use of his or her medical data for genetic research, at least as long as these data may still be identifiable.     

Active control for seismic response reduction using modal-fuzzy approach

An active modal-fuzzy control method using hydraulic actuators is presented for seismic response reduction. In the proposed control system, a new fuzzy controller designed in the modal space produces the desired active control force. This type controller has all advantages of the fuzzy control algorithm and modal approach. Since it is very difficult to select input variables used in fuzzy controller among numerous state variables in the active fuzzy control system, the presented algorithm adopts the modal control algorithm to be able to consider information of all state variables in civil structures that are usually dominated by first few modes. In other words, all information of the whole structure can be considered in the control algorithm evaluated to reduce seismic responses and it can be efficient for civil structures especially. In addition, the presented algorithm is expected to magnify utility and performance caused by efficiency that the fuzzy algorithm can handle complex model more easily. An active modal-fuzzy control scheme is applied together with a Kalman filter and a low-pass filter to be applicable to real civil structures. A Kalman filter is considered to estimate modal states and a low-pass filter was used to eliminate spillover problem. The results of the numerical simulations for a wide amplitude range of loading conditions and for historic earthquake show that the proposed active modal-fuzzy control system can be beneficial in reducing seismic responses of civil structures.     

Sorption hysteresis on microrough surfaces

Numerical experiments on the adsorption of water vapor based on vapor silver substrates with different microroughness were performed using a modified Langmuir adsorption model. The calculations revealed a number of phenomena making it possible to clarify the interpretation of many experimental data on sorption. It is established that significant initial microroughness of a silver substrate causes a sharp increase in the number of molecules of an equilibrium adsorbate and provides a stable liquid film of the adsorbate under conditions close to saturation conditions. It is shown that stability of the film state is due to the fact that its further growth or evaporation are only possible because of nucleation processes under significant supersaturation or overheating. The results obtained can be used to improve technologies based on adsorption processes.     

昆虫飞行参数测量实验研究进展

在昆虫飞行的实验研究中,可采用活体实验、模型实验和活体模型结合三种方法。活体实验可以客观反映自然界中昆虫的飞行规律,获得真实的实验数据,但可重复性差。模型实验作为机械装置可以重复进行试验,详细描述流场结构并定量各种参数大小,但与真实飞行存在一定差距。单独使用这两种中的任一方法均可对一些现象给出了解释。二者相结合的方法更易于准确描述昆虫的运动特征,通过对比模型与活体的结果来提出机理,尽管需要的实验周期较长,但结论往往更接近真实状态,基于该方法科学家们已提出了几种飞行机理。本文结合近几年文献报道,综述了昆虫飞行参数测量方法,并对以上几种方法在研究昆虫飞行机理中的作用进行了对比分析,认为模型和活体结合的研究方法更容易为一些飞行现象提出合理解释。     

Photoelastic coatings

While photoelastic-model analysis is an effective method to measure stresses, its practical use is limited to solving problems under well-defined loading conditions which can be successfully applied on a simulated basis to the model. Further, model analysis does not take into account such conditions as hidden material defects, assembly stresses, residual stresses, inelastic behavior, and other parameters that are contributing factors to the structural integrity of a part or structure. On the other hand, with photoelastic coatings, the stress analysis is conducted on real parts operating under actual service conditions. The coating reveals the true surface strains occurring on a part, since most, if not all, of the contributing stress conditions mentioned above can be taken into account during testing. Photoelastic coatings are easy to apply and, with proper test planning, are very economical to use. Since a visible picture of the stress field is provided over the entire area coated, intelligent application of the technique can save many hours of testing time and provide quick solutions to design or service-failure problems.     

Complex system and influence of delayed decision on the stability of a triopoly price game model

A triopoly price game model has been established based on nonlinear and economics theories in this paper, and all 3 firms of triopoly market are supposed to make a price decision with bounded rationality. By discrete dynamical system theory and jury condition, we obtain the expression of Nash equilibrium point’s stable region. Then traditional two-dimensional and creative three-dimensional diagrams of the local stable region are given by numerical simulation, and both 2D and 3D diagrams showed us some law about the Nash equilibrium point’s stable region. First, the number of time-delay decision makers has no necessary relationship with system stability; Second, under the same number of time-delay decision makers, the delay parameter has a positive influence of system stability, i.e., the price making relying more on current period profits can lower the system risk of falling into chaos. These results have significant theoretical and practical value to the price making of firms in related markets.     

Genetics in primary care: a USA faculty development initiative

The Genetics in Primary Care (GPC) project is a USA national faculty development initiative with the goal of enhancing the training of medical students and primary care residents by developing primary care faculty expertise in genetics. Educational strategies were developed for the project by an executive committee with input from an advisory committee, comprising individuals with primary care, medical education and genetics expertise. These committees identified the key issues in genetics education for primary care as (1) considering inherited disease in the differential diagnosis of common disorders; (2) using appropriate counseling strategies for genetic testing and diagnosis, and (3) understanding the implications of a genetic diagnosis for family members. The group emphasized the importance of a primary care perspective, which suggests that the clinical utility of genetic information is greatest when it has the potential to improve health outcomes. The group also noted that clinical practice already incorporates the use of family history information, providing a basis for discussing the application of genetic concepts in primary care. Genetics and primary care experts agreed that educational efforts will be most successful if they are integrated into existing primary care teaching programs, and use a case-based teaching format that incorporates both clinical and social dimensions of genetic disorders. Three core clinical skills were identified: (1) interpreting family history; (2) recognizing the variable clinical utility of genetic information, and (3) acquiring cultural competency. Three areas of potential controversy were identified as well: (1) the role of nondirective counseling versus shared decision-making in discussions of genetic testing; (2) the intrinsic value of genetic information when it does not influence health outcomes, and (3) indications for a genetics referral. The project provides an opportunity for ongoing discussion about these important issues.     

A numerical model for the transport of salinity in estuaries

In this paper, a numerical model for the simulation of the hydrodynamics and of the evolution of the salinity in shallow water estuaries is presented. This tool is intended to predict the possible effects of Civil Engineering public works and other human actions (dredging, building of docks, spillages, etc.) on the marine habitat, and to evaluate their environmental impact in areas with high productivity of fish and of seafood. The prediction of these effects is essential in the decision making about the different options that could be implemented. The mathematical model consists of two coupled systems of differential equations: the shallow water hydrodynamic equations (that describe the evolution of the depth and of the velocity field) and the shallow water advective–diffusive transport equation (that describes the evolution of the salinity level). Some important issues that must be taken into account are the effects of the tides (including that the seabed could be exposed), the volume of fresh water provided by the rivers and the effects of the winds. Thus, different types of boundary conditions are considered. The numerical model proposed for solving this problem is a second‐order Taylor–Galerkin finite element formulation. The proposed approach is applied to a real case: the analysis of the possible effects of dredging Los Lombos del Ulla, a formation of sandbanks in the Arousa Estuary (Galicia, Spain). A number of simulations have been carried out to compare the actual salinity level with the predicted situation if the different dredging options were executed. Some of the obtained results are presented and discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

土体各向异性边界面模型研发的几个问题探讨

土体边界面模型通过采用塑性模量场插值,来反映土体变形的非线性,边界面模型适合对小应变情况下的土体非线性变形进行模拟. 在Wheeler 模型的基础上,结合边界面理论,构造一个土体各向异性边界面模型,模型可以反映天然土体的各向异性特性. 本文对该模型研发过程中遇到的几个问题进行理论探讨,为理解和掌握各向异性边界面理论,并进一步进行新型边界面模型的研发,提供了理论借鉴.     

Solitary waves for Non-Destructive Testing applications: Delayed nonlinear time reversal signal processing optimization

An original signal processing method called delayed Time Reversal-Nonlinear Elastic Wave Spectroscopy is introduced in the present paper. The method could be used to amplify signal in certain regions of the material under Non Destructive Testing. It allows to optimize and change the shape of the received focused wave in the material, either by making the focusing sharper by decreasing the side lobes or making it wider by modifying the actual focusing peak. It is also possible to use the focused signal as a delta-basis to construct a signal with arbitrary envelope or reduce the side lobes of the focused signal. These concepts are shown to work well in the simulations and the physical experiments. This signal processing method is particularly promising for nonlinear and solitary wave analysis, since it allows to create an interaction of sharp and solitary wave peaks just underneath the receiving transducer. Due to simple and accurate linear prediction of the received interaction signal, any differences of measurements and predictions could indicate the presence of nonlinearities.     

Spectral simulation and shock absorber identification

In vehicle dynamics shock absorbers are used for the optimization of driving comfort and driving safety. Therefore, it is necessary to identify characteristics of shock absorbers under real conditions. This paper introduces the use of hardware-in-the-loop simulations for the identification of shock absorbers involving stochastic models of the road roughness. For this purpose a dynamic hydraulic test stand is used replacing the classical mechanical test stands which allow only sinusoidal excitation. For the Monte Carlo simulation with a real shock absorber in the loop, the random excitation of ground roughness is generated using a modified spectral representation method based on the famous contributions of Shinozuka. Motion and force of the shock absorber are measured and fed back to the Monte Carlo simulation of a car model in real time. The characteristic of the shock absorber is identified using the classical least squares method and a correlation-based method. A piecewise linear model for the characteristic relating the damping force and the velocity of the piston is applied for the shock absorber identification.