384 research outputs found

    Characterizations of Soil Collapsibility: Effect of Salts Dilution

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    Collapsibility of soils is the large change in volume of soil upon saturation or wetting.Ā  This change may or may not be the result of the application of additional load.Ā  Soil at a construction site may not always be suitable for supporting structures such as buildings, bridges, highways, and dams.Ā  For example, if soil is placed in a certain none desire density, a large settlement will occur either due to loading or wetting of soil deposits.Ā  Hence, a collapse will occur which will create a large subsidence or a sinkhole.In this study, soil samples of CL-ML soil were modified by adding different amounts of brine.Ā  The main goal of which was to examine the effect of brine presence on the collapse potential of the soil.Ā  Soil index properties, compaction characteristics, and a collapse potential were evaluated according to ASTM standards.Ā  The test includes Atterberg's limit, Harvard miniature compaction, and double oedometer tests.It has been shown that brine additive has pronounced effect on the Atterbergā€™s limits; it is clearly shown that as the amount of brine increases both liquid limit and plastic limit decrease.Ā  Compaction curve characteristics of soil were altered by the presence of brine, the maximum dry density, obtained using Harvard miniature device, increased as brine percentage increased, however, the optimum moisture content showed substantial decrease with increasing the amount of brine.

    Characterizations of Soil Collapsibility: Effect of Salts Dilution

    Get PDF
    Collapsibility of soils is the large change in volume of soil upon saturation or wetting.Ā  This change may or may not be the result of the application of additional load.Ā  Soil at a construction site may not always be suitable for supporting structures such as buildings, bridges, highways, and dams.Ā  For example, if soil is placed in a certain none desire density, a large settlement will occur either due to loading or wetting of soil deposits.Ā  Hence, a collapse will occur which will create a large subsidence or a sinkhole.In this study, soil samples of CL-ML soil were modified by adding different amounts of brine.Ā  The main goal of which was to examine the effect of brine presence on the collapse potential of the soil.Ā  Soil index properties, compaction characteristics, and a collapse potential were evaluated according to ASTM standards.Ā  The test includes Atterberg's limit, Harvard miniature compaction, and double oedometer tests.It has been shown that brine additive has pronounced effect on the Atterbergā€™s limits; it is clearly shown that as the amount of brine increases both liquid limit and plastic limit decrease.Ā  Compaction curve characteristics of soil were altered by the presence of brine, the maximum dry density, obtained using Harvard miniature device, increased as brine percentage increased, however, the optimum moisture content showed substantial decrease with increasing the amount of brine.

    Low complexity interference aware distributed resource allocation for multi-cell OFDMA cooperative relay networks

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    In this paper we focus on the subcarrier allocation for the uplink OFDMA based cooperative relay networks. Multiple cells were considered, each composed of a single base station (destination), multiple amplify and forward (AF) relay stations and multiple subscriber stations (sources). The effects of inter-cell interference (ICI) have been considered to optimize the subcarrier allocation with low complexity. The optimization problem aims to maximize the sum rate of all sources and at the same time maintain the fairness among them. Full channel state information (CSI) is assumed to be available at the base station. In the proposed algorithm the subcarrier allocation is performed in three steps; firstly the subcarriers are allocated to the Relay Stations (RSs) by which the received ICI on each RS is minimized. Then, the pre-allocated subcarriers are allocated to subscribers to achieve their individual rate requirements. Finally the remaining subcarriers are allocated to subscribers with the best channel condition to maximize the total sum of their data rates. The results show that the proposed algorithm significantly reduces the complexity with almost the same achievable rate of the optimal allocation in a single cell case. In case of multi-cell, the proposed algorithm outperforms the conventional algorithm in terms of total network achievable data rate and overall network complexity. Ā©2010 IEEE

    Timing of Colonization of Caries-Producing Bacteria: An Approach Based on Studying Monozygotic Twin Pairs

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    Findings are presented from a prospective cohort study of timing of primary tooth emergence and timing of oral colonization of Streptococcus mutans (S. mutans) in Australian twins. The paper focuses on differences in colonization timing in genetically identical monozygotic (MZ) twins. Timing of tooth emergence was based on parental report. Colonization timing of S. mutans were established by plating samples of plaque and saliva on selective media at 3 monthly intervals and assessing colony morphology. In 25% of individuals colonization occurred prior to emergence of the first tooth. A significant proportion of MZ pairs (21%) was discordant for colonization occurring before or after first tooth emergence, suggesting a role of environmental or epigenetic factors in timing of tooth emergence, colonization by S. mutans, or both. These findings and further application of the MZ co-twin model should assist in development of strategies to prevent or delay infection with S. mutans in children

    Utility-based resource allocation for interference limited OFDMA cooperative relay networks

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    Ā© 2016 Elsevier B.V. This paper proposes a utility-based resource allocation algorithm for the uplink OFDMA Inter-cell Interference (ICI) limited cooperative relay network. Full channel state information (CSI) is assumed to be available at the resource controller at initial stage, then the work is extended to consider more realistic assumption, i.e., only partial channel state information (PCSI) is available. The proposed algorithm aims to maximize the total system utility while simultaneously satisfying the individual user's minimum data rate requirements. In the proposed algorithm, relay selection is initially performed based on the consideration of ICI. Then, subcarrier allocation is performed to achieve maximum utility assuming equal power allocation. Finally, based on the amount of ICI, a modified water-filling power distribution algorithm is proposed and used to optimize the per-carrier power allocation across the allocated set of subcarriers. The results show that, compared to conventional algorithms, the proposed algorithm significantly improves system performance in terms of total sum data rate, outage probability and fairness

    A Hybrid Fuzzy Genetic Algorithm for an Adaptive Traffic Signal System

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    This paper presents a hybrid algorithm that combines Fuzzy Logic Controller (FLC) and Genetic Algorithms (GAs) and its application on a traffic signal system. FLCs have been widely used in many applications in diverse areas, such as control system, pattern recognition, signal processing, and forecasting. They are, essentially, rule-based systems, in which the definition of these rules and fuzzy membership functions is generally based on verbally formulated rules that overlap through the parameter space. They have a great influence over the performance of the system. On the other hand, the Genetic Algorithm is a metaheuristic that provides a robust search in complex spaces. In this work, it has been used to adapt the decision rules of FLCs that define an intelligent traffic signal system, obtaining a higher performance than a classical FLC-based control. The simulation results yielded by the hybrid algorithm show an improvement of up to 34% in the performance with respect to a standard traffic signal controller, Conventional Traffic Signal Controller (CTC), and up to 31% in the comparison with a traditional logic controller, FLC

    COPD care delivery pathways in five European Union countries : mapping and health care professionals' perceptions

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    Background: COPD is among the leading causes of chronic morbidity and mortality in the European Union with an estimated annual economic burden of ā‚¬25.1 billion. Various care pathways for COPD exist across Europe leading to different responses to similar problems. Determining these differences and the similarities may improve health and the functioning of health services. Objective: The aim of this study was to compare COPD patientsā€™ care pathway in five European Union countries including England, Ireland, the Netherlands, Greece, and Germany and to explore health care professionalsā€™ (HCPs) perceptions about the current pathways. Methods: HCPs were interviewed in two stages using a qualitative, semistructured email interview and a face-to-face semistructured interview. Results: Lack of communication among different health care providers managing COPD and comorbidities was a common feature of the studied care pathways. General practitioners/family doctors are responsible for liaising between different teams/services, except in Greece where this is done through pulmonologists. Ireland and the UK are the only countries with services for patients at home to shorten unnecessary hospital stay. HCPs emphasized lack of communication, limited resources, and poor patient engagement as issues in the current pathways. Furthermore, no specified role exists for pharmacists and informal carers. Conclusion: Service and professional integration between care settings using a unified system targeting COPD and comorbidities is a priority. Better communication between health care providers, establishing a clear role for informal carers, and enhancing patientsā€™ engagement could optimize current care pathways resulting in a better integrated system
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