Rheological and nanomechanical characterization of aging in polymer modified asphalt

In this study, change in rheological and nanomechanical properties of asphalt due to aging is determined in the laboratory. Asphalt binders are aged using Rolling Thin Film Oven (RTFO), Pressure Aging Vessel (PAV), and draft ovens. Asphalt binder includes an unmodified base binder, Styrene-Butadiene (SB) and Styrene-Butadiene-Styrene (SBS) polymer modified binders. Rheological properties such as viscosity, phase angle, shear modulus, creep compliance, stiffness, etc. are determined using Dynamic Shear Rheometer (DSR) test, Multiple Stress Creep Recovery (MSCR) test, Bending Beam Rheometer (BBR) test, Rotational Viscosity (RV) test and the Direct Tension (DT) test. Nanomechanical properties such as hardness and reduced elastic modulus are determined using a nanoindenter. Laboratory test results are expressed in terms of Aging Index (AI) defined by relative change in specific rheological or nanomechanical property of aged and unaged binder. As it was expected, binder rheological properties such as stiffness increases and phase angle and creep compliance decrease due to aging. Based on aging index defined by complex shear modulus (G*), increase in percentage of polymer results in decrease in the AI value for both SB and SBS modified binder. It means percent increase of polymer is not good for long term stability but may be good for fatigue. When comparing AI defined by G* of SB and SBS, it is shown that SBS has higher AI than SB. Aging index of RTFO condition binder does not vary as significantly as it varies in PAV conditioned sample. When comparing AI defined by G*, elastic modulus (G\u27), viscous modulus (G\u2033), of oven aged sample, base binder ages more than modified binder and G\u27 changes exponentially compared to the linear change of G\u2033. At low temperature, the difference in creep compliance of unaged and aged binder is small compared to that at high temperature. This confirms that temperature significantly affects aging. Based on AI defined by BBR stiffness, original binder shows AI value similar to the modified binder. Again, SBS has higher AI defined BBR stiffness than SB. Based on ductility measured in DT test, it can be said as sample ages its ductility reduces. Nanoindentation is conducted on thin asphalt binder film deposited on glass slides. For both unmodified and modified binders, hardness and reduce modulus increase exponentially due to aging. Nanoindentation results show similar trend obtained by rheological test. Aging decreases the creep compliance defined by indentation depth, similar trend is observed in MSCR test by DSR

Assessing the rates of channel shifts, bend development and bank erosion hazard on the Sajó River (Hungary) by aerial and terrestrial photogrammetry

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Detecting the role of land use / land cover on river bank processes (Study area: Talar River, Iran)

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The impact of intellectual capital disclosure on common cost of equity in the companies listed in Tehran Stock Exchange

Nowadays, the use of non- tangible assets due to its competitive advantage has significant impact on the success and survival of organizations, hence the identification, measurement, and management of intellectual capital is of particular importance and makes real value of the organizations revealed. The impact of intellectual capital disclosures provides useful information to assist actual and potential investors in making rational decisions. The aim of this study was to investigate the impact of intellectual capital disclosure and its components on the sort of equity in the period of five years from 2008 to 2012 in the companies listed in Tehran stock exchange. Thus, 80 stock companies were considered as the samples and for this study, four hypotheses have been considered. The variables of the study were first identified and excel software was used to calculate the variables which are independent from Palyk model to measure the variables of the study. The data were analyzed by SPSS Statistics software version 20 and applying descriptive and inferential statistics such as correlation analysis, multiple regressions to test the hypotheses. The results of the statistical hypothesis test show there is a positive and significant relationship between intellectual capital disclosure and common Cost of equity. Also, the results indicated that the effect of the two components from the components of the intellectual capital - structural capital and human capital disclosure - on the independent variable, common Cost of equity, is not significant, but the impact of Capital Employed Disclosure on common cost of equity was significant, positive and reasonable

The impact of intellectual capital disclosure on common cost of equity in the companies listed in Tehran Stock Exchange

Nowadays, the use of non- tangible assets due to its competitive advantage has significant impact on the success and survival of organizations, hence the identification, measurement, and management of intellectual capital is of particular importance and makes real value of the organizations revealed. The impact of intellectual capital disclosures provides useful information to assist actual and potential investors in making rational decisions. The aim of this study was to investigate the impact of intellectual capital disclosure and its components on the sort of equity in the period of five years from 2008 to 2012 in the companies listed in Tehran stock exchange. Thus, 80 stock companies were considered as the samples and for this study, four hypotheses have been considered. The variables of the study were first identified and excel software was used to calculate the variables which are independent from Palyk model to measure the variables of the study. The data were analyzed by SPSS Statistics software version 20 and applying descriptive and inferential statistics such as correlation analysis, multiple regressions to test the hypotheses. The results of the statistical hypothesis test show there is a positive and significant relationship between intellectual capital disclosure and common Cost of equity. Also, the results indicated that the effect of the two components from the components of the intellectual capital - structural capital and human capital disclosure - on the independent variable, common Cost of equity, is not significant, but the impact of Capital Employed Disclosure on common cost of equity was significant, positive and reasonable

Model development and validation of bituminous-based crack sealants

A wide spectrum of sealant types commonly used in the United States were installed in eight different test sites using two types of sealing treatment techniques. The performance of sealants was monitored after each winter for three years to determine a performance index (PI) consisting primarily of adhesive, cohesive, and overband wear. Field samples were collected from the sites to conduct laboratory testing and validate the sealant grading system. According to the field results, most sealants failed below a PI threshold of 70% after three years. In general, rout and seal sections performed better than the clean and seal sections. Field performance results highlighted the importance of test site selection, especially for clean and seal application. Statistical correlations of tests parameters with the field performance were performed. A composite score approach, combining ranking and correlation, was used to develop a quantitative scale for determining the level of acceptance. Based on the composite score, a strong or acceptable correlation was obtained between field performance and laboratory test parameters for field test sites. After confirming the correlation between field performance and lab results, the thresholds for test method were selected or fine-tuned. In addition to test methods validation, an investigation was also conducted to evaluate the short-term and long-term aging effects of hot-poured crack sealants through a differential aging test. Rheological and mechanical properties of sealants at different aging stages were monitored to characterize the aging effects. Laboratory aging of sealants was studied using three different aging methods: Kettle aging, melter aging, and vacuum oven aging (VOA). The aging index was used to evaluate the effect of these aging methods. Comparing the stiffness master curves obtained from the crack sealant bending beam rheometer (CSBBR) test for field-aged samples and laboratory-aged samples, VOA was validated as a reasonable aging method for simulating two-five years of field aging. Finally, sealant rheological, mechanical and chemical properties were analyzed, implementing different performance-based tests and FTIR test to characterize sealants aging. A set of eight types of crack sealants was exposed to approximately four years of weathering conditions. Aging mechanisms were investigated by comparing the critical properties with those obtained at the time of installation inside a small kettle. Samples were collected every six months after installation for laboratory characterization. Laboratory characterization includes low temperature stiffness, high temperature modulus, viscosity, and FTIR spectrum. According to the results of the experimental program, a consistent increase was observed in the low temperature stiffness and high temperature shear modulus of crack sealants due to weathering. The study showed that the low- and high-temperature properties of surface portion are significantly influenced by weathering effects even within a short period of life time. A superposition rule analogous to time–temperature superposition for viscoelastic materials was applied to develop master curves. A phenomenological aging model was developed as a function of aging time. Based on their aging potential, sealants were categorized into three groups at low and high temperatures with increasing aging potential: Type A, Type B, and Type C. FTIR analysis showed that rate of carbonyl index was significantly higher at the crust of crack sealants. On the other hand, the bottom part of field-aged crack sealants exhibited a higher sulfuxide index

Performance assessment of individual and ensemble data-mining techniques for gully erosion modeling

Gully erosion is identified as an important sediment source in a range of environments and plays a conclusive role in redistribution of eroded soils on a slope. Hence, addressing spatial occurrence pattern of this phenomenon is very important. Different ensemble models and their single counterparts, mostly data mining methods, have been used for gully erosion susceptibility mapping; however, their calibration and validation procedures need to be thoroughly addressed. The current study presents a series of individual and ensemble dataminingmethods including artificial neural network (ANN), support vector machine (SVM), maximum entropy (ME), ANN-SVM, ANN-ME, and SVM-ME to map gully erosion susceptibility in Aghemam watershed, Iran. To this aim, a gully inventory map along with sixteen gully conditioning factors was used. A 70:30% randomly partitioned sets were used to assess goodness-of-fit and prediction power of the models. The robustness, as the stability ofmodels' performance in response to changes in the dataset, was assessed through three training/test replicates. As a result, conducted preliminary statistical tests showed that ANN has the highest concordance and spatial differentiation with a chi-square value of 36,656 at 95% confidence level,while theME appeared to have the lowest concordance (1772). The ME model showed an impractical result where 45% of the study area was introduced as highly susceptible to gullying, in contrast, ANN-SVMindicated a practical resultwith focusing only on 34% of the study area. Through all three replicates, the ANN-SVM ensemble showed the highest goodness-of-fit and predictive power with a respective values of 0.897 (area under the success rate curve) and 0.879 (area under the prediction rate curve), on average, and correspondingly the highest robustness. This attests the important role of ensemble modeling in congruently building accurate and generalized models which emphasizes the necessity to examine different models integrations. The result of this study can prepare an outline for further biophysical designs on gullies scattered in the study area

Changes in morphometric meander parameters identified on the Karoon River, Iran, using remote sensing data

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Spatio-temporal variation of throughfall in a hyrcanian plain forest stand in Northern Iran

Elucidating segregation of precipitation in different components in forest stands is important for proper forest ecosystems management. However, there is a lack of information on important rainfall components viz. throughfall, interception and stemflow in forest watersheds particularly in developing countries. We therefore investigated the spatiotemporal variation of important component of throughfall for a forest stand in a Hyrcanian plain forest in Noor City, northern Iran. The study area contained five species of Quercus castaneifolia, Carpinus betulus, Populus caspica and Parrotia persica. The research was conducted from July 2013 to July 2014 using a systematic sampling method. Ninetysix throughfall collectors were installed in a 3.5 m × 3.5 m grid cells. The canopy covers during the growing/leaf-on (i.e., from May to November) and non-growing/leaf-off (i.e., from December to March) seasons were approximately 41% and 81%, respectively. The mean cumulative throughfall during the study period was 623±31 mm. The average throughfall (TF) as % of rainfall (TFPR) during leaf-on and leaf-off periods were calculated 56±14% and 77±10%, respectively. TF was significantly (R2 = 0.97, p = 0.00006) correlated with gross precipitation. Percent of canopy cover was not correlated with TF except when gross precipitation was <30 mm. A comparison between leaf-off and leaf-on conditions indicated a significantly higher TFPR and corresponding hotspots during leaf-on period. TFPR also differed between seasons with a maximum amount in winter (82%). The results of the study can be effectively used by forest watershed managers for better perception of hydrological behavior of the Hyrcanian forest in the north of Iran under different silvicultural circumstances leading to getting better ecosystem services