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Alaejos P.,CEDEX | Alaejos P.,Polytechnic University of Mozambique | Lanza V.,CEDEX | Bermudez M.A.,Ministry of Public Works | Velasco A.,CEDEX
Cement and Concrete Research | Year: 2014

The accelerated mortar bar test (AMBT) is one of the most common tests to detect reactive aggregates although it has some limitations: there is no agreement on the limit of expansion, fails appear when testing slowly reactive aggregates and a laborious work is needed to find the pessimum content. An experimental programme on the AMBT has been carried out to overcome these limitations. Rapid and slowly reactive aggregates extracted from real Spanish structures affected by alkali silica reaction have been used. As a result, the test detected correctly all the reactive aggregates, but with the following requirements: a limit of 0.10% at 14 days for rapid reactive aggregates and 0.20% at 90 days for slowly reactive aggregates. Also the pessimum content has been found between 5 and 15 vol% of equivalent reactive quartz, giving a peak expansion of 0.42% (14 days). The expansion after this peak decreased but it was always over 0.10%. © 2014 Published by Elsevier Ltd.

Zaied A.N.H.,Zagazig University | Al Othman W.,Ministry of Public Works
Expert Systems with Applications | Year: 2011

In a conventional traffic signals controller, the lights change at constant cycle time. In many cities, automatic traffic signals are often based on a constant green-to-red cycle. The time period for green light (or red light) to be on is determined based on a stochastic model. The traditional vehicle-actuated control of isolated intersections attempts continuously to adjust green times. The decision to change green light duration involves fuzzy factors that cannot be precisely determined. The main objective of this paper is to develop a fuzzy logic traffic system that considers the two two-way intersections and is able to adjust changes in time intervals of a traffic signal based on traffic situation level. The proposed system has been applied and tested using real data collected from signalized intersection in Hawalli governorate in the State of Kuwait. Twenty-seven iterations have been done; the results show that the proposed fuzzy logic traffic system provides better performance in terms of total waiting time, total moving time, and vehicle queue. Finally, it can be observed from the results that the proposed system can be used to accelerate the cycle time and to give other phases the chance to gain more benefit from the green time lost. © 2011 Published by Elsevier Ltd.

Khozaimy O.,Ministry of Public Works | Al-Dhaheri A.,Abu Dhabi Company for Onshore Oil Operations | Ullah A.M.M.S.,Kitami Institute of Technology
Applied Soft Computing Journal | Year: 2011

Real-life decision problems are often solved by using a very limited set of data points. The computational complexity of such decision problems can be handled easily by using a mathematical entity called stochastic point cloud (SPC). In general, SPC is a form of granular information and is simulated by a data-driven stochastic process. In this study, particular interests are given on normal-distribution-driven SPCs. When the parameters of a normally distributed variable is not clearly known due to the lack of information or due to the multiplicity of regression analysis, it forms a set of SPCs. Three types of such SPCs are described in detail in this study. The effectiveness of such SPCs in solving a real-life decision problem (i.e., how to minimize vehicle emissions in Abu Dhabi Emirate of United Arab Emirates) is also shown. To develop more realistic and man-machine-friendly decision support systems one can use SPCs. © 2010 Elsevier B.V. All rights reserved.

Sanchez-Gonzalez J.F.,Center for Harbours and Coastal Studies | Sanchez-Rojas V.,Ministry of Public Works | Memos C.D.,National Technical University of Athens
Journal of Hydraulic Research | Year: 2011

An experimental study carried out in a flume to a scale of 1/20 is presented to assess the wave height attenuation induced by submerged meadows of Posidonia oceanica. After examination of the appropriate scaling laws and selection of the model material, an extensive test programme included both regular and random waves. A semi-empirical formulation for estimating the wave height transformation along the meadow is obtained, based on energy conservation and considering that dissipation is only due to drag forces. The latter were linearized to obtain an exponential decay law. The formulation proposed depends on the drag coefficient and includes also an empirical parameter accounting for wave steepness. The model improves previous results and extends its applicability to random waves. The drag coefficient associated to the meadows is found to be better related to the Keulegan-Carpenter parameter than to the Reynolds number. Its value is given also for models proposed by others. © 2011 Copyright International Association for Hydro-Environment Engineering and Research.

Timmerman J.G.,Ministry of Public Works | Beinat E.,University of Salzburg | Beinat E.,VU University Amsterdam | Termeer K.,Wageningen University | Cofino W.,Wageningen University
Environmental Management | Year: 2010

Water quality monitoring has developed over the past century from an unplanned, isolated activity into an important discipline in water management. This development also brought about a discontent between information users and information producers about the usefulness and usability of information, in literature often referred to as the data-rich-but-information-poor syndrome. This article aims to gain a better understanding of this issue by studying the developments over some five decades of Dutch national water quality monitoring, by analyzing four studies in which the role and use of information are discussed from different perspectives, and by relating this to what is considered in literature as useful information. The article concludes that a "water information gap" exists which is rooted in different mutual perceptions and expectations between the two groups on what useful information is, that can be overcome by improving the communication. Such communication should be based on willingness to understand and deal with different mindframes and should be based on a methodology that guides and structures the interactions. © 2010 Springer Science+Business Media, LLC.

Prendes-Gero M.-B.,University of Oviedo | Alvarez-Fernandez M.-I.,University of Oviedo | Lopez-Gayarre F.,University of Oviedo | Drouet J.-M.,Université de Sherbrooke | Junco J.R.-V.,Ministry of Public Works
Structural and Multidisciplinary Optimization | Year: 2016

This paper illustrates the cost optimization of steel frame structures by mean of genetic algorithm developed from the Eugenics Evolutionary theory. The aim is to obtain a final structure with a minimum cost. To this end, a modified multiple objective function has been defined. This considers cost as the result of a summary where elements like welds, simple connections, or the number of structural elements, have an influence on the final result. According to the Eugenics Evolutionary theory, a new selection operator has been developed in a way that leads to all members of the population being able to have descendants and avoids the loss of any kind of genetic material. In addition, the penalization coefficients have been optimised and the effect of parameter setting has been investigated, to achieve convergence faster through penalising the most expensive structures and looking for the optimum range of parameters’ value. The result is a robust genetic algorithm which, compared with others, achieves better optimum individuals and does not stop at local minima. Finally, two different two-dimensional truss frames have been optimized and the results have been compared with those obtained using different methods of selection like elitism, steady-state replacement, roulette wheel, and tournament selection. © 2016 Springer-Verlag Berlin Heidelberg

Fernandez J.A.,Technical University of Madrid | Martinez C.,Technical University of Madrid | Magdaleno F.,Ministry of Public Works
Environmental Science and Policy | Year: 2012

In Europe, the Water Framework Directive (2000/60/EC) demands the achievement of a good ecological status for water bodies by 2015. However, it also defines exceptions to these objectives, such as a good ecological potential instead of a good ecological status or a more distant temporal horizon than 2015. Those exceptions may only be applied to heavily modified water bodies (HMWBs). This paper presents a method, P-IAHRIS, incorporated into the free software IAHRIS v2.2, that offers objective criteria for the preliminary designation of HMWBs downstream from irrigation dams, flood protection dams or drinking water supply dams. The procedure incorporates two indicators: (i) the P10%-90% indicator, which analyses the alterations in the flow regime associated with the range of natural variability defined by the 10th and 90th percentiles of the annual and monthly discharges; and (ii) the IHA-HMWB indicator, which assesses the changes in the magnitude, seasonality, variability and duration of natural flows. P-IAHRIS was applied to 103 water bodies in Spain. The functionality and versatility of the method have been proven and allow the fast and objective preliminary designation of HMWBs, both in the Mediterranean and Atlantic environments. © 2011 Elsevier Ltd.

Adekristi A.,Ministry of Public Works | Eatherton M.R.,Virginia Polytechnic Institute and State University
Journal of Earthquake Engineering | Year: 2015

Time-domain spectral matching of an earthquake ground motion consists of iteratively adding sets of wavelets to an acceleration history until the resulting response spectrum sufficiently matches a target spectrum. The spectral matching procedure is at its core a nonlinear problem because the addition of a wavelet often causes shifting in the time of peak response or creation of a larger second peak at a different time. A modification to existing time-domain spectral matching algorithms is proposed using Broyden updating for solving the set of nonlinear equations. Three wavelet bases are evaluated and the corrected tapered cosine wavelet is selected. The proposed algorithm is then tested and compared with other methods that are commonly used for spectral matching. The results show that the proposed algorithm is able to match the target spectrum while reasonably preserving the spectral nonstationarity, energy development, and the frequency content of the original time histories. © 2015, Taylor & Francis. All rights reserved.

Abusam A.,Kuwait Institute for Scientific Research | Al-Rashidi H.,Ministry of Public Works | Shahalam A.,Kuwait Institute for Scientific Research
Desalination and Water Treatment | Year: 2012

Conventional reverse osmosis (RO) treatment deprives reclaimed wastewater of nutrients and other essential elements for plant growth. One way to make the RO reclaimed wastewater suitable for agricultural irrigation purposes is to blend it with a tertiary effluent. This paper assesses the suitability of the quality of RO permeate and tertiary effluent admixture for agricultural irrigation, using the WHO guidelines for irrigation waters. Obtained results indicated that the admixture is suitable for agricultural irrigation, but with some restrictions. Unsuccessful attempt to predict the quality of the admixture, using only ideal mixing principles, confirmed that effluent storage reservoirs (ESRs) constitute a complex ecosystem. © 2012 Desalination Publications. All rights reserved.

Dewi R.C.,Ministry of Public Works
34th Asian Conference on Remote Sensing 2013, ACRS 2013 | Year: 2013

Animation is one of potential methods to visualize change of phenomena in time series. But users might be overwhelmed by the number of changes displayed in an animation of long time series. Users then need to reduce the amount of information displayed. Since different phenomena may change in different time intervals, modifying temporal unit tools are developed as supporting tools for improving animation environment. This paper presents the development of the tools in ILWIS, an open source GIS software package. As a case study, NDVI data derived from satellite images SPOT VEGETATION are used to implement the functionalities of the tools. The tools propose advanced functionality for animating and interacting with time, filtering data by their attribute, and aggregating data by time unit. Equipped with time series graph and proposed time selection tools, animation allows users to answer visual exploration questions related to attribute (what), location (where) and time (when, how long, how often).

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