- نمایش
**15 محصول در هر صفحه**

## A Neurofuzzy Decision Framework for the Management of Water Distribution Networks

0 تومانAmong the most important components of sustainable management strategies for water distribution networks is the ability to integrate risk analysis and asset management decision-support systems (DSS), as well as the ability to incorporate in the analysis financial and socio-political parameters that are associated with the networks in study. Presented herein is a neurofuzzy decision-support system for the performance of multi-factored risk-of-failure analysis and pipe asset management, as applied to urban water distribution networks. The study is based on two datasets (one from New York City and the other from the city of Limassol, Cyprus), analytical and numerical methods, and artificial intelligence techniques (artificial neural networks and fuzzy logic) that capture the underlying knowledge and transform the patterns of the network’s behaviour into a knowledge-repository and a DSS.

## A new wavelet-based method for determination of mode shapes: Experimental Results

0 تومانIn this article a new method is proposed to determine the mode shapes of linear dynamic systems from the results of wavelet analysis. A previously proposed method based on a modified Morlet wavelet function with an adjusting parameter is used to identify the natural frequencies and damping ratios of system. The mode shapes are obtained from the time signal of responses and the extracted natural frequencies from wavelet transform of response signals. The method is applied to a steel real beam excited by an impact force. It is shown that the extracted mode shapes are not scaled. Therefore, the mass change method is used for scaling of the mode shapes.

## A Review on the Viable Technology for Construction Waste Recycling

0 تومانEnvironmental problems have been considered as a serious situation in the construction. Waste management is pressing harder with the alarming signal warning the industry. Reuse, recycling and reduce the wastes consider as the only methods to recover those waste generated; however, the implementations still have much room for improvement. This paper reviews the technology on construction waste recycling and their viability. Ten material recycling practices are studied, including: i) asphalt; ii) brick; iii) concrete; iv) ferrous metal; v) glass; vi) masonry; vii) non-ferrous metal; viii) paper and cardboard; ix) plastic; and x) timber. The viable technology of the construction material recycling should be provided an easy reference for future applications. Keywords: Materials, recycling, asphalt, brick, concrete, ferrous metal, glass, masonry, non-ferrous metal, paper and cardboard, plastic, timber, construction.

## A Robust Approach to Estimate the Uniaxial Compressive Strength of Intact Rocks

0 تومانThe uniaxial compressive strength of intact rocks is extensively used in many rock engineering projects. High-quality core samples are required for the uniaxial compressive strength determinations. However, such core samples cannot always be obtained from weak rocks. For this reason, the predictive models are often employed to estimate indirectly. In present study, various models have been developed in order to predict uniaxial compressive strength. For this purpose different tests were accomplished. The root mean square error index was calculated as 6.1 from the neuro-fuzzy model and 13.63 from the multiple regression model. As a result, performance index reveled that the neuro-fuzzy exhibited a very high prediction capacity

## A simplified Nonlinear Sway-Rocking model for evaluation of seismic response of structures on shallow foundations

0 تومانThis paper presents a simplified Nonlinear Sway-Rocking model as a preliminary design tool for seismic soil-structure interaction analysis. The proposed model is intended to capture the nonlinear loaddisplacement response of shallow foundations during strong earthquake events where foundation bearing capacity is fully mobilised. Emphasis is given to heavily-loaded structures resting on a saturated clay half-space. The variation of soil stiffness and strength with depth, referred to as soil non-homogeneity, is considered in the model. Although independent springs are utilised for each of the swaying and rocking motions, coupling between these motions is taken into account by expressing the loaddisplacement relations as functions of the factor of safety against vertical bearing capacity failure (FSv) and the moment-to-shear ratio (M/H). The simplified model has been calibrated and validated against results from a series of static push-over and dynamic analyses performed using a more rigorous finitedifference numerical model. Despite some limitations of the current implementation, the concept of this model gives engineers more degrees of freedom in defining their own model components, providing a good balance between simplicity, flexibility and accuracy.

## A soft soil model that accounts for creep

0 تومانThe well-known logarithmic creep law for secondary compression is transformed into a differential form in order to include transient loading conditions. This 1-D creep model for oedometer-type strain conditions is then extended towards general 3-D states of stress and strain by incorporating concepts of Modified Cam- Clay and viscoplasticity. Considering lab test data it is shown that phenomena such as undrained creep, overconsolidation and aging are well captured by the model.

## A Teaching Guide for Structural Steel Connections

0 تومانConnection design in an introductory steel course is often difficult to effectively communicate. Time constraints and priority of certain other topics over connection design also tend to inhibit sufficient treatment of connection design. The Steel Connections Teaching tool kit is an attempt to effectively incorporate the fundamentals of steel connection design into a first course in steel design. The tool kit addresses three broad issues that arise when teaching students steel connection design: visualization, load paths, and limit states. In structural analysis classes, students are shown idealized structures. Simple lines represent beams and columns, while pins, hinges, and fixed supports characterize connections. However, real structures are composed of beams, girders, and columns, all joined together through bolting or welding of plates and angles. It is no wonder that students have trouble visualizing and understanding the true threedimensional nature of connections! The steel sculpture provides a convenient means by which full-scale steel connections may be shown to students. The steel sculpture exhibits over 20 different connections commonly used in steel construction today. It is an exceptional teaching instrument to illustrate structural steel connections. The steel sculpture’s merit is nationally recognized as more than 90 university campuses now have a steel sculpture modeled after Dr. Ellifritt’s original design. In addition to the steel sculpture, this booklet provides illustrations, and each connection has a short description associated with it.

## Active Earth Pressure of Modeled Strip Load Surcharge on Rigid Walls

0 تومانIn determination of the active earth pressure of strip load surcharge, we would always do elastic supposition, and for that, we used boussinesq. In this essay, by supposition of plastic environment of the earth, a new formula was presented for the effect of strip load surcharge on the wall. In this new formula, effects of gradient, and the friction angle between earth and wall, and gradient of the wall, and friction angle of earth, is considered. In this essay, by MATLAB software, a program is presented for calculation of the pressure on the wall in different situations of setting strip load surcharge. Also this essay considers the distance of the effect of strip load surcharge, and by mean of that, we can determine the length of the surcharge and the distance of surcharge from wall which has taken effects from the imported pressure. It should be pointed out that imported pressure totally consists of earth pressure and surcharge pressure. This essay expresses the considered stress distribution, under the effect of strip load surcharge on the wall having the effect of the earth behind it. And dependent on the situation of strip load surcharge, we present four kinds of distribution.

## ADAPTING BUILDINGS AND CITIES FOR CLIMATE CHANGE

0 تومانThe war against climate change pitches mankind against a global threat that vastly eclipses that of terrorism,1 in battles that have already claimed the lives of hundreds of thousands of ordinary men and women from every continent. Climate change has led us into an era in which war and conflict are endemic,2 the widespread extinction of species approaches catastrophic proportions,3 andwhole regions and countries will be lost beneath the swelling seas and the expanding deserts of a rapidly warming world. And the really bad news is that ‘the world has only one generation, perhaps two, to save itself’.4 We all instinctively know, already, that the climate is changing, from the small noticed things like the unseasonable patterns of the flowering of plants, the falling of snow and the growing in strength of the wind and the rain. With this knowledge comes a growing apprehension of danger. Deep down, in quiet moments, we ask ourselves questions that a year or two ago were unthinkable: ● What will I do when the lights do go out? ● Will the house flood next year? ● Will my home get so hot this summer that I won’t be able to stay in it? ● How long could I survive in this building without air conditioning? ● Where will we go? ● Will we survive? This book is written to enable you, the reader, to get a clearer view of the ways in which the climate is changing and how these changes will affect your life tomorrow and the day after, in the buildings, settlements and regions in which you live and work.

## Adaptive boundary control of a flexible marine installation system

0 تومانIn this paper, boundary control of a marine installation system is developed to position the subsea payload to the desired set-point and suppress the cable’s vibration. Using Hamilton’s principle, the flexible cable coupled with vessel and payload dynamics is described as a distributed parameter system with one partial differential equation (PDE) and two ordinary differential equations (ODEs). Adaptive boundary control is proposed at the top and bottom boundaries of the cable, based on Lyapunov’s direct method. Considering the system parametric uncertainty, the boundary control schemes developed achieve uniform boundedness of the steady state error between the boundary payload and the desired position. The control performance of the closed-loop system is guaranteed by suitably choosing the design parameters. Simulations are provided to illustrate the applicability and effectiveness of the proposed control.

## Advanced Structural Dynamics and Active Control of Structures

0 تومانFlexible structures in motion have specific features that are not a secret to a structural engineer. One of them is resonance—strong amplification of the motion at a specific frequency, called natural frequency. There are several frequencies that structures resonate at. A structure movement at these frequencies is harmonic, or sinusoidal, and remains at the same pattern of deformation. This pattern is called a mode shape, or mode. The modes are not coupled, and being independent they can be excited separately. More interesting, the total structural response is a sum of responses of individual modes. Another feature—structural poles—are complex conjugate. Their real parts (representing modal damping) are typically small, and their distance from the origin is the natural frequency of a structure.

## An Adaptive IHS Pan-Sharpening Method

0 تومانThe goal of pan-sharpening is to fuse a low spatial resolution multispectral image with a higher resolution panchromatic image to obtain an image with high spectral and spatial resolution. The Intensity-Hue- Saturation (IHS) method is a popular pan-sharpening method used for its efficiency and high spatial resolution. However, the final image produced experiences spectral distortion. In this letter, we introduce two new modifications to improve the spectral quality of the image. First, we propose imageadaptive coefficients for IHS to obtain more accurate spectral resolution. Second, an edge-adaptive IHS method was proposed to enforce spectral fidelity away from the edges. Experimental results show that these two modifications improve spectral resolution compared to the original IHS and we propose an adaptive IHS that incorporates these two techniques. The adaptive IHS method produces images with higher spectral resolution while maintaining the high-quality spatial resolution of the original IHS .

## Analytical solution for axisymmetric thermoelastodynamic problems in a transversely isotropic half-space under a surface loading

0 تومانIn the present study, the theory of coupled thermoelastodynamic is applied to determine the displacement, temperature and stress (DTS) fields of a torsionless axisymmetric transversely isotropic half-space under a surface loading. The basic equations of coupled thermoelasticity consist of the equations of motion and the energy equation, which forms a set of completely coupled partial differential equations for the displacement and temperature fields. Potential method is employed for uncoupling the set of basic equations of coupled thermoelasticity. With the aid of a potential function existed in the literature, the system of equations are uncoupled, where a sixth order partial differential equation is received. Displacement components and temperature are written with respect to the potential function in cylindrical coordinate system. The Laplace and Hankel integral transforms are employed to suppress the time and radial variables, respectively. One may apply the inverse Hankel and Laplace transforms to determine the DTS fields and other quantities of interest in physical (space-time) domain. Eventually, the integrand functions of DTS components are obtained analytically.

## Analyzing Uncertainty in Civil Engineering

0 تومانThe characteristic shear strength parameters of soil are obviously decisive for the geotechnical design. Characteristic parameters are defined as cautious estimates of the soil parameters affecting the limit state. It is shown how geotechnical engineers interpret this cautious estimate. Due to the inherent lack of data in geotechnical investigations there is always a certain degree of subjectivity in assessing the characteristic soil parameters. The range of characteristic shear parameters assigned to the same set of laboratory experiments by 90 geotechnical engineers has been used to design a spread foundation. The resulting geometrical dimensions are remarkably different. It is concluded that geotechnical calculations are rather estimates than exact predictions. Thus for intricate geotechnical projects a sensitivity analysis should be performed to find out critical scenarios. Furthermore a continuous appraisal of the soil properties during the construction process is indispensable.

## APPLICATION OF SEISMIC BASE ISOLATION TECHNOLOGY IN IRAN

0 تومانApplication of base isolation techniques in Iran goes back to hundreds of years ago and even to ancient times. Installing pieces of wood between the foundation and the walls of buildings is among the earthquake resistant construction techniques that have been applied in some areas of Iran in the past. However, contrary to other technologies which are generally adapted soon after their development, modern seismic base isolation technology took almost a quarter of a century to be adapted and utilized in Iran. This paper presents the historical as wells as the modern application of seismic base isolation technology in Iran.