Characterization of Warm Mix Asphalt (WMA) performance in different asphalt applications

With the prices of crude oil increasing and reserves of natural nonrenewable resources dwindling over time, the needs for adopting greener and more sustainable approaches in various construction activities are stronger. The asphalt production industry has been keen during the last few decades to reduce the impact of its activities on the environment especially regions adjacent to its operating activities and on natural resources. Thus, recycled materials such as reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) are increasingly being used in the production of asphalt mixtures. Moreover, different techniques to produce and place asphalt mixtures at lower temperatures than the typical hot mix asphalt (HMA) temperatures are recently being used. These techniques are currently known as warm mix asphalt (WMA) technologies. The performance of three commonly used warm mix technologies: Advera, Evotherm J1 and Sasobit were examined in comparison to a control HMA mixture with respect to dynamic modulus and permanent deformation (flow number). Each mixture was developed using a PG 64-22 binder and two types of aggregates: limestone or quartzite. In addition, this study will look into whether WMA additives enable the production of high RAP content (30%) mixtures with comparable performance to HMA. Warm mix asphalt mixtures prepared at 120°C and compacted at 110°C showed no concerns regarding workability or compactability even in mixtures incorporating 30% RAP. Dynamic modulus and flow number tests were conducted to assess the stiffness and permanent deformation resistance, respectively. The performance tests data suggested that there is a significant difference in the performance of HMA mixtures and the three WMA technologies investigated. Dynamic modulus data of WMA mixtures were consistently lower compared to HMA, with the difference in E* values decreasing with increasing temperature. The incorporation of RAP increased the dynamic modulus of all mixtures but HMA mixture was still higher than WMA mixtures. The impact of RAP incorporation decreased as temperature increased. Finally, the rutting resistance of WMA mixtures was considerably lower compared to HMA mixes even after incorporation of RAP. Thus, WMA technologies suitability for hot regions needs to further investigated. MEPDG design runs were performed to assess the performance of lab produced asphalt mixtures incorporating WMA and RAP and compare it to the performance of corresponding control mixtures. MEPDG output agreed with laboratory test results specifically for rutting prediction and terminal IRI values. The statistical analysis of variance indicated that the EvothermTM mixtures performance was generally different from the control mixtures regardless of type of aggregates used. Finally, the rheological behavior of two binders: a base binder and a polymer modified binders incorporating two types of warm mix asphalt (WMA) additives were studied through an extensive testing scheme. The warm mix additives used were an organic wax and an oily chemical additive. Tests performed comprise basic rheological tests such as rotational viscometer, viscous flow, creep, temperature and frequency sweeps. The output data of these tests were used to construct Viscosity-Temperature Susceptibility (VTS) curves and master curves to study the behavior of the binders tested. The performance of the unmodified WMA binders was similar to the control binder at the midrange and high test temperatures. On the other hand, the modified binder incorporating the waxy WMA additive exhibited stiffer behavior indicating the presence of more advanced polymer networks within the binder structure. Moreover, the wax additive had an anti-oxidizing effect on the aging rate of the binder using pressure aging vessel (PAV)

Using the Brink Depth in Discharge Measurement for Inverted Semicircular Open Channels

A free overfall at the end of an open channel provides a simple means for measuring flow discharge. The semicircular open channel plays a significant role in various applications, and it is of interest to calculate its discharge. This paper presents the application of the momentum equation to evaluate the use of a smooth inverted semicircular channel end as devised to calculate the discharge if the end depth is known. The experiments were performed in three separate semicircular inverted channels, with diameters of 15.0 cm, 18.4 cm, and 24.2 cm. The experimental data used to develop equations for calculating the discharge from known end depth. Where the end depth is related to the critical depth, and the end depth ratio value was found to be 0.8102 for a critical depth-diameter ratio of up to 0.40. On the other hand, the relationships for end depth ratio and non-dimensional discharge are defined. Two empirical equations are generated for the direct and indirect prediction of discharges from known end depth values

Stochastic Programming for Selection Variables in Cluster Analysis

Cluster analysis is one of the most important techniques in the exploratory data analysis; it is goal to discover a natural grouping in a set of observations without knowledge of any class labels.  Variable selection has been very important for a lot of research in several areas of application. The study suggested a stochastic programming approach which selects the most important variables in clustering a set of data. The study evaluates the performance of the stochastic programming suggested approach for selection variables in cluster analysis used numerical example. The suggested stochastic programming approach selects the most important variable in cluster analysis simultaneously and the results are satisfied

The Effect of Barium Content on the Crystallization and Microhardness of Barium Fluormica Glass-Ceramics

Mica glass-ceramics are easily machined due to their “House-of-Cards” microstructure. Barium fluormica glass-ceramics were developed and indicated good mechanical properties. This work studies the effect of varying barium content on the crystallization and microhardness of mica glass-ceramics. Four glasses were produced with different baria contents, then converted to mica glass-ceramics using a two-step heat treatment. They were characterized using Differential Scanning Calorimetry [DSC], X-ray Diffraction [XRD], Scanning electron microscopy [SEM] and Vickers microhardness. DSC showed some formulations indicated bulk crystallisation as the dominant mechanism. XRD showed the crystallization of Barium fluorphlogopite in all the compositions with minor secondary phases. SEM showed the formation of “House-of-Cards” microstructures and with an increase in BaO content, a decrease in contrast was observed in back scattered mode. Exceptionally low hardness values (<2 GPa) were obtained for longer heat treatments/holding times and are related to the well-developed house-of-cards microstructures formed

Robustness of Firm-Specific and Macroeconomic Determinants of Exploration Investments: Implications from Egyptian Oil & Gas Industry

The uncertainty that surrounds Oil and Gas exploration environments call for an examination at different angles. In terms of robustness, this study focuses on three performance measurements: (a) the amount of exploration investments, (b) the growth rate of exploration investments and (c) the Value at Risk (VaR) of exploration investments.The study utilizes the properties of discriminant analysis for deriving Z-score models that can be used for monitoring firms\u27 performance. A co-integration analysis is utilized as well in order to examine the level of co-integration between predictors of each performance measure. The sample includes annual data for forty one firms (local and multinational) working in the Oil and Gas industry in Egypt for the period 2009-2014.The results show that (a) amount and growth of exploration investment are quite robust performance measures in the Oil and Gas industry, (b) VaR of exploration investment is sporadic as it firm-specific, (c) GDP, Capital expenditure and operating expenditure are quite relevant for managing and monitoring growth of exploration investments.The study offers robust evidence that amount and growth of exploration investment are quire relevant firm performance in the Oil and Gas Industry

PKCAM: Previous Knowledge Channel Attention Module

Recently, attention mechanisms have been explored with ConvNets, both across the spatial and channel dimensions. However, from our knowledge, all the existing methods devote the attention modules to capture local interactions from a uni-scale. In this paper, we propose a Previous Knowledge Channel Attention Module(PKCAM), that captures channel-wise relations across different layers to model the global context. Our proposed module PKCAM is easily integrated into any feed-forward CNN architectures and trained in an end-to-end fashion with a negligible footprint due to its lightweight property. We validate our novel architecture through extensive experiments on image classification and object detection tasks with different backbones. Our experiments show consistent improvements in performances against their counterparts. Our code is published at https://github.com/eslambakr/EMCA

Lyn Hejinian's and Charles Bernstein's language poetics : a postmodern conceptual grammar

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