A risk‐based life cycle cost strategy for optimal design and evaluation of control methods for nonlinear structures

The lack of direct correspondence between control objectives and hazard risks over the lifetime of systems is a key shortcoming of current control techniques. This along with the inability to objectively analyze the benefits and costs of control solutions compared with conventional methods has hindered widespread application of control systems in seismic regions. To address these gaps, this paper offers 2 new contributions. First, it introduces risk‐based life cycle–cost (LCC) optimal control algorithms, where LCC is incorporated as the performance objective in the control design. Two strategies called risk‐based linear quadratic regulator and unconstrained risk‐based regulator are subsequently proposed. The considered costs include the initial cost of the structure and control system, LCC of maintenance, and probabilistically derived estimates of seismic‐induced repair costs and losses associated with downtime, injuries, and casualties throughout the life of the structure. This risk‐based framework accounts for uncertainties in both system properties and hazard excitations and uses outcrossing rate theory to estimate fragilities for various damage states. The second contribution of this work is a risk‐based probabilistic framework for LCC analysis of existing and proposed control strategies. The proposed control designs are applied to the nonlinear model of a 4‐story building subjected to seismic excitations. Results show that these control methods reduce the LCC of the structure significantly compared with the status quo option (benefits of up to $1 351 000). The advancements offered in this paper enhance the cost‐effectiveness of control systems and objectively showcase their benefits for risk‐informed decision making.     

Exploiting the use of physical information for the calibration of a lumped hydrological model

In hydrological modelling, the challenge is to identify an optimal strategy to exploit tools and available observations in order to enhance model reliability. The increasing availability of data promotes the use of new calibration techniques able to make use of additional information on river basins. In the present study, a lumped hydrological model—designed with the aim of utilizing remotely sensed data—is introduced and calibrated, adopting four different schemes that adopt, to varying extents, available physical information. The physically consistent conceptualization of the hydrological model used allowed development of a step by step calibration based on a combination of information, such as remotely sensed data describing snow cover, recession curves obtained from streamflow measurements, and time series of surface run‐off obtained with a baseflow mathematical filter applied to the streamflow time‐series. Results suggest that the use of physical information in the calibration procedure tends to increase model reliability with respect to approaches where the parameters are calibrated using an overall statistic based, considerably or exclusively, on streamflow data.     

镇江市地下水动态变化规律研究

通过线性回归、非线性回归和遗传算法分别建立了本区地下水水位与地下水开采量、降雨量之间的关系方程。结果表明 ,地下水水位多年动态主要受控于岩溶水的人工开采 ,而降雨量对其影响甚小。     

Dynamic Model Re-construction and Corresponding Abnormal Characteristics Anatomy of Subtropical High based on Actual DataTime SeriesSamples

Aiming at the abnormal activity of West Pacific Subtropical High(WPSH) inducing the serious flood disaster in 1998, and considering the complex seasonal activity of WPSH in summer, based on the actual geopotential height field time series observational data in 1998, a non-linear dynamic model of WPSH was reconstructed by using the idea of dynamic system retrieval and genetic algorithms. Combined with the synchronous actual weather process, the corresponding dynamic characteristics and variation mechanism of WPSH, such as the equilibrium state destabilization and bifurcation of the WPSH system, were analyzed and discussed. The research showed that due to the advantages of global optimization and parallel calculation of GA, a nonlinear dynamic model could be reasonably and quickly reconstructed, and the reconstructed nonlinear dynamic model of WPSH derived from the actual abnormal case data could be used for describing objectively and explaining reasonably the basic characteristics and the abnormal activity process of WPSH. The dynamic discussion showed that the configuration and diversification of WPSH system equilibriums, such as bifurcation, catastrophe had a good matching with the actual medium short period abnormal activity of WPSH, such as northward jumping and southward droping, as well as double-ridge line pattern. The modality of WPSH geopotential height field induced by multi-equilibriums destabilization was more complex than that of by single-equilibriums bifurcation, and their exhibition patterns were more different. With the forcing parameters increaseing, closing with and exceeding critical value, the WPSH system equilibrium state destabilization or bifurcation would occur. Especially, when the equilibrium state jump/drop from low/high to the high/low value, corresponding WPSH system behaved as a leap northward /fall southward, moreover, when the stable equilibriums state from 1 to 2, corresponds with the pattern of “double-ridges” phenomenon of WPSH, contrariwise, “double-ridges” phenomenon would disappear. A meaningful technique route was provided to the mechanism research and dynamic characteristic discussion for the complex weather system of hardly modeling such as WPSH.     

Nonlinear evaluations of unconditionally stable explicit algorithms

Two explicit integration algorithms with unconditional stability for linear elastic systems have been successfully developed for pseudodynamic testing.Their numerical properties in the solution of a linear elastic system have been well explored and their applications to the pseudodynamic testing of a nonlinear system have been shown to be feasible. However,their numerical properties in the solution of a nonlinear system are not apparent.Therefore,the performance of both algorithms for use in the solution...     

Automated lithological mapping by integrating spectral enhancement techniques and machine learning algorithms using AVIRIS-NG hyperspectral data in Gold-bearing granite-greenstone rocks in Hutti,India

In this study, we proposed an automated lithological mapping approach by using spectral enhancement techniques and Machine Learning Algorithms (MLAs) using Airborne Visible Infrared Imaging Spectroradiometer-Next Generation (AVIRIS-NG) hyperspectral data in the greenstone belt of the Hutti area, India. We integrated spectral enhancement techniques such as Principal Component Analysis (PCA) and Independent Component Analysis (ICA) transformation and different MLAs for an accurate mapping of rock types. A conjugate utilization of conventional geological map and spectral enhancement products derived from ASTER data were used for the preparation of a high-resolution reference lithology map. Feature selection and extraction methods were applied on the AVIRIS-NG data to derive different input dataset such as (a) all spectral bands, (b) shortwave infrared bands, (c) Joint Mutual Information Maximization (JMIM) based optimum bands, and (d) optimum bands using PCA, to choose optimum input dataset for automated lithological mapping. The comparative analysis of different MLAs shows that the Support Vector Machine (SVM) outperforms other Machine Learning (ML) models. The SVM achieved an Overall Accuracy (OA) and Kappa Coefficient (k) of 85.48% and 0.83, respectively, using JMIM based optimum bands. The JMIM based optimum bands were more suitable than other input datasets to classify most of the lithological units (i.e. metabasalt, amphibolite, granite, acidic intrusive and migmatite) within the study area . The sensitivity analysis performed in this study illustrates that the SVM is less sensitive to the number of samples and mislabeling in the model training than other MLAs. The obtained high-resolution classified map with accurate litho-contacts of amphibolite, metabasalt, and granite can be coupled with an alteration map of the area for targeting the potential zone of gold mineralization.     

平均风向的计算方法及其比较

常用的平均风向４种计算方法分别是算术平均法，标量平均法，单位矢量法和矢量法，利用则资料对各种方法的计算结果进行比较，结果表明：算术平均法加大了偏南风的比重，标 在风向变化３６０°时有可能出现较大的误差，在应用时间须加以注意；单位矢量法与矢量法的结果比较一致，且不需风速的同期观测资料，是一种比较好的方法。     

一种基于遗传算法的影像匹配方法研究

影像匹配是计算机视觉及数字摄影测量的核心问题。基于遗传算法优良的全局寻优特点及影像匹配的具体特点,将遗传算法引入到遥感影像的匹配定位中,针对基本遗传算法易提前收敛的特点,对基本遗传算法进行了一定的自适应改进。实验结果表明这种方法可以产生一个快速而且可靠的匹配结果。     

Review of the algebraic linear methods and parallel implementation in numerical simulation of groundwater flow

The desire to increase spatial and temporal resolution in modeling groundwater system has led to the requirement for intensive computational ability and large memory space. In the course of satisfying such requirement, parallel computing has played a core role over the past several decades. This paper reviews the parallel algebraic linear solution methods and the parallel implementation technologies for groundwater simulation. This work is carried out to provide guidance to enable modelers of groundwater systems to make sensible choices when developing solution methods based upon the current state of knowledge in parallel computing.