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1.
Andrea Carpinteri 《Computers & Structures》1992,44(6):1317-1338
An automated procedure is developed to determine the influence of a crack detected in a structural element subjected to cyclic combined axial and bending loadings with constant amplitude. A theoretical formulation for fatigue crack growth analysis is presented and the results obtained are compared with the experimental data of the Wöhler curves. The critical crack configurations for which the fatigue failure occurs after a given number of loading cycles can be obtained from the above-mentioned comparison. Finally, an example is shown in order to illustrate the use of a computer program, which translates the proposed procedure. 相似文献
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M. R. Hansen 《Structural and Multidisciplinary Optimization》1993,5(3):145-151
A method for automated dimensional synthesis of arbitrary planar mechanisms is presented. The method is based on identification of the mutually independent vector branches of the mechanism to be synthesized. These branches form the independent vector loops of the mechanism, and the design equations that fulfil the desired kinematic behaviour are easily formulated on the basis of these loops. The identification of the branches can be made by a separation of the mechanism into modules in which advantage is taken of the fact that any planar mechanism may be subdivided into a number modules (input bodies and Assur groups).As the design equations are strongly nonlinear (involving both dimensions and rotations of bodies), a continuation method is employed to solve them. The continuation method consists of a sequence of analyses of a mechanism of the desired topology in which the kinematic behaviour of the mechanism is gradually changed to the desired kinematic behaviour in a number of steps. In each of these steps it is possible to determine the mechanism that fulfils the currently prescribed kinematic behaviour using one of two solution procedures, where the mechanism of the previous step is used as an initial guess. One solution procedure finds an exact solution, the other uses a minimization technique.This method, with the definition and analysis of the initial mechanism, the division of the mechanism into modules, the definition of the desired kinematic behaviour, and the generation and solution of the vector loop equations, has been implemented in a computer program package.Presented at NATO ASI Optimization of Large Structural Systems, Berchtesgaden, Germany, Sept. 23 – Oct. 4, 1991 相似文献
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Predicted climate change impact on future water availability in the Murray–Darling Basin (MDB) has highlighted the need for a whole of basin model that incorporates various physical and management characteristics for planning and operational purposes. Modelling platforms such as eWater Source Integrated Modelling System (Source) offer a useful framework in this regard, but at present lack automated calibration techniques to parameterise river system models.This paper presents an automated river system calibration procedure which is robust, repeatable, transparent and systematic. The procedure allows for river network calibration (as opposed to isolated reach by reach calibration), since this has more utility for basin planning and prediction. The calibration procedure routs upstream flow, estimates ungauged inputs via rainfall–runoff (RR) models, and estimates flow based split (distributary) functions and loss functions in complex river systems.This procedure was tested in the Northern Murray–Darling Basin (MDB) and results from the Border Rivers catchment are presented. The results from the Border Rivers case study demonstrate the applicability of the procedure with median calibration and evaluation NSE values of 0.88 and 0.79, respectively. The use of this procedure in the Border Rivers region has highlighted the likelihood of changing stream channel connections at higher flows in the lower reaches of the river network. 相似文献
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"三S"技术与农业发展 总被引:10,自引:1,他引:9
党的十五大提出:“坚持农业放在经济工作的首位,…大力推进科教兴农,发展高产、优质、高效农业和节水农业。”随着信息革命发展起来的遥感(RS)、全球定位系统(GPS)和地理信息系统(GIS)三大空间科学技术,已成为兴农的高科技手段为世人所关注。本文简要介绍”三S”技术的当前发展,叙述“三S”技术在土地资源调查、土壤侵蚀调查、农作物估产与监测、灾害监测与评估等方面的应用,并着重论述‘”三S”技术在精细农业‘(Precisionagricuiture)中的应用。主要结论是“三S”技术将从为农业服务发展到直接参与农业生产的全过程,从而实现农业生产的信息化。 相似文献
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A FORTRAN IV, large capacity, computer program has been developed to determine collapse loads and bifurcation loads for linear and nonlinear prebuckling behavior for fiber-reinforced, laminated, rectangular plates and panels under general loading systems and boundary conditions. The program is based on the principle of total potential energy and uses finite-differences in the discretization process. Whole-station spacing has been used to calculate the strain energy associated with an area-element and an orthogonal finite-difference grid that provides for variable spacings in perpendicular directions is incorporated.Numerical results are presented that compare favorably with results obtained via the general computer program STAGS. Other numerical results are presented that illustrate the types of boundary conditions, applied loads, cut-outs and initial geometric imperfections that can be handled by the present program. A brief study of the effect of panel construction and initial geometric imperfections on the buckling behavior of fiber-reinforced panels is presented. 相似文献
6.
Man-Lai Tang Wai-Yin PoonLeevan Ling Yijie LiaoHang-Wai Chui 《Computational statistics & data analysis》2011,55(2):955-963
The asymptotic and exact conditional methods are widely used to compare two ordered multinomials. The asymptotic method is well known for its good performance when the sample size is sufficiently large. However, Brown et al. (2001) gave a contrary example in which this method performed liberally even when the sample size was large. In practice, when the sample size is moderate, the exact conditional method is a good alternative, but it is often criticised for its conservativeness. Exact unconditional methods are less conservative, but their computational burden usually renders them infeasible in practical applications. To address these issues, we develop an approximate unconditional method in this paper. Its computational burden is successfully alleviated by using an algorithm that is based on polynomial multiplication. Moreover, the proposed method not only corrects the conservativeness of the exact conditional method, but also produces a satisfactory type I error rate. We demonstrate the practicality and applicability of this proposed procedure with two real examples, and simulation studies are conducted to assess its performance. The results of these simulation studies suggest that the proposed procedure outperforms the existing procedures in terms of the type I error rate and power, and is a reliable and attractive method for comparing two ordered multinomials. 相似文献
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Urban growth models operating at finer spatial scale usually incorporate a subdivision module that carries out automated partitioning of the lands selected for future development. In this paper, we describe the development and implementation of Parcel-Divider – a GIS toolset for automated subdivision of land parcels. In addition to automating the process of generating urban layouts such as city blocks, streets and cadastral lots, the toolset is capable of extending roads to new subdivisions. Researchers can integrate the toolset into their modeling while planners can use it as a standalone application to visualize scenarios of infrastructure arrangements in growing areas of the city. Our tool-generated subdivision configurations closely match the subdivision styles observed in real-world cities when compared visually as well as statistically. 相似文献
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GIS和GPS在交通中的应用 总被引:6,自引:0,他引:6
地理信息系统(GIS)正在以前所未有的速度应用到各个领域中,而全球定位系统(GPS)也已开始应用于交通运输和道路工程之中,该文介绍了利用GIS软件实现车载GPS实时跟踪并在指挥中心的数字地图上集中显示。 相似文献
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This paper proposes a general system approach applicable to the automatic inspection of textured material. First, the input image is preprocessed in order to be independent of non-uniformities. A tone-to-texture transform is then performed by mapping the original grey level picture on a multivariate local feature sequence, which turns out to be normally distributed. More specifically, features derived with the help of the Karhunen-Loève decomposition of a small neighbourhood of each pixel are used. A decision as to conformity with a reference texture is arrived at by thresholding the Mahalanobis distance for every realization of the feature vector. It is shown that this approach is optimum under the Gaussian assumption in the sense that it has a minimum acceptance region for a fixed probability of false rejection. 相似文献
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Dell'Anna R Demichelis F Barbareschi M Sboner A 《Computer methods and programs in biomedicine》2005,79(3):197-208
Tissue Microarray (TMA) methodology has been recently developed to enable "genome-scale" molecular pathology studies. To enable high-throughput screening of TMAs automation is mandatory, both to speed up the process and to improve data quality. In particular, in acquiring digital images of single tissues (core sections) a crucial step is the correct recognition of each tissue position in the array. In fact, further reliable data analysis is based on the exact assignment of each tissue to the corresponding tumor. As most of the times tissue alignment in the microarray grid is far from being perfect, simple strategies to perform proper acquisition do not fit well. The present paper describes a new solution to automatically perform grid location assignment. We developed an ad hoc image processing procedure and a robust algorithm for object recognition. Algorithm accuracy tests and assessment of working constraints are discussed. Our approach speeds up TMA data collection and enables large scale investigation. 相似文献
14.
Shahar Weksler Gila Notesco Eyal Ben-Dor 《International journal of remote sensing》2017,38(15):4481-4493
The at-sensor radiance of a pixel in a longwave infrared (LWIR) image represents the surface temperature, the surface emissivity, which is similar during the day and at night, and the atmospheric contribution, which is expressed differently during the day and at night. Based on this, an automated procedure, which locates pixels for which each absorption feature in their radiance during the day appears as an emission feature at night, indicative of atmospheric contribution, was developed. The average day or night spectrum of these indicative pixels was applied as a gain factor spectrum to the entire day or night image, respectively, reducing the atmospheric contribution and emphasizing the surface spectral features, represented by emissivity, of each pixel in the image. The procedure was examined on LWIR hyperspectral data cubes acquired over two different areas, and enabled effective reduction of the atmospheric features in both area data sets. 相似文献
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本系统采用将GPS信息通过GPRS的SOCKET通讯实时传递到多个GIS控制中心的电子地图显示修补系统,解决了实时绘制、动态显示、同步更新、限区定制等电子地图更新维护的瓶颈问题,可快速、高效、联网、互动地实现地理信息的更新,为通常费时费力的电子地图制作更新提供了新的切入点。 相似文献
17.
Abdel-Ghaffar K.A.S. El Abbadi A. 《Parallel and Distributed Systems, IEEE Transactions on》1994,5(1):87-93
We study the problem of identifying corrupted pages between two remotely located copies of a file in a distributed system. An efficient deterministic algorithm is presented to identify up to any given number of differing pages. The algorithm requires a single exchange of messages and is based on the structure of the Reed-Solomon code. In order to identify up to f corrupted pages, 2f signatures are transmitted. The algorithm requires less communication costs than previously proposed solutions. In fact, we prove that our algorithm is optimal, in the sense that no other algorithm is guaranteed to identify with probability 1 the corrupted pages by exchanging less information 相似文献
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This paper develops a procedure that enables an engineer to present a more compelling argument for process control investment. The procedure calculates an economic measure of the dynamic robustness of plant control systems in the face of plant-based and external uncertainties. It involves: (a) characterising each type of plant-based or external uncertainty that affects operations and profitability; (b) computer-simulating a plant-control system model to show how it responds to different combinations of uncertainties; (c) calculating an economic index of control quality for each combination of uncertainties; and (d) plotting a frequency distribution of the economic indices. The tighter the distribution, the more robust the plant-control system. The procedure is demonstrated by comparing the robustness of a distillation column control system, with and without decoupling. This procedure has three advantages. Firstly, it presents a more realistic picture of robustness because it characterises uncertainty by a range of probable values, rather than a single value. Secondly, the procedure can be applied to SISO, MIMO, linear and nonlinear systems alike without requiring model simplification. Thirdly, it presents results in economic terms using a graphical format that is more meaningful to business managers than an abstract mathematical quantity, such as a structured singular value. 相似文献
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《Computers & chemistry》1989,13(1):61-67
An integration routine, written in Pascal, is shown that can automatically choose end points for infrared spectral peak integration. The routine accepts data generated from JCAMP-DX software. This paper includes a listing of the program and shows some of its limitations. 相似文献