Analysis of Resilient Modulus of Dense- and Open-Graded Aggregates

1996 ◽  
Vol 1547 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Andrew G. Heydinger ◽  
Qinglu Xie ◽  
Brian W. Randolph ◽  
Jiwan D. Gupta
Keyword(s):  
Resilient Modulus ◽  
Linear Regression Analysis ◽  
Natural Stone ◽  
Moisture Condition ◽  
Bulk Stress ◽  
Octahedral Shear Stress ◽  
Log Linear ◽  
Moisture Conditions ◽  
Material Gradation ◽  
Two Parameter

The results of analyses of laboratory resilient modulus testing conducted on dense-graded and open-graded aggregates are presented. The testing program included three different aggregate materials (crushed limestone, natural stone, and slag), five different gradation specifications, and three different moisture conditions (dry, moist, and saturated). In addition to the five aggregate specifications, test specimens were prepared so that they would satisfy the lower, central, and upper bounds for the gradations. Resilient modulus tests were conducted as closely as possible according to Strategic Highway Research Program Protocol P-46 (AASHTO T 294-92 I). The test results were analyzed using log-linear regression analysis with two-parameter (bulk stress) and three-parameter (bulk stress and octahedral shear stress) expressions for resilient modulus. The results of the testing indicate that the resilient modulus of aggregates and regression constants vary significantly depending on the type of material and vary less significantly depending on material gradation and moisture condition. The natural stone aggregates had the higher moduli and the slag aggregate had the lowest moduli. The resilient modulus does not vary significantly as the moisture content increases unless the aggregate becomes saturated. The R2 values are consistently higher using a three-parameter expression than a two-parameter expression.

scholarly journals Resilient Properties of Soil-Rock Mixture Materials: Preliminary Investigation of the Effect of Composition and Structure

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1658 ◽  
Author(s):  
Junfeng Qian ◽  
Yongsheng Yao ◽  
Jue Li ◽  
Hongbin Xiao ◽  
Shenping Luo
Keyword(s):  
Shear Stress ◽  
Stress State ◽  
Triaxial Test ◽  
Resilient Modulus ◽  
Discrete Element ◽  
Modeling Method ◽  
Triaxial Tests ◽  
Crushed Rock ◽  
Bulk Stress ◽  
Octahedral Shear Stress

The physical composition and stress state of soil-rock mixture (SRM) materials have a crucial influence on their mechanical properties, and play a vital role in improving the performance of subgrade. To reveal the resilient behavior and mesostructure evolution of SRM materials, triaxial tests and discrete element method (DEM) numerical analysis have been carried out. In the triaxial test section, the mechanical response of SRM materials was investigated by preparing samples under different stress states and physical states and conducting triaxial tests on samples. Simultaneously, a new irregular particle modeling method was developed and applied to the discrete element modeling process to analyze the mesostructure evolution of SRM materials under cycling loading. First, a cyclic triaxial test of SRM material is performed on the SRM material, and the effects of bulk stress, octahedral shear stress and rock content on the resilient modulus of the SRM material are analyzed. It is revealed that the resilient modulus increases with increasing bulk stress and rock content, and decreases with increasing octahedral shear stress. Based on a new resilient modulus prediction model, the relationships among the rock content, stress state and resilient modulus are established. Then, based on an improved DEM modeling method, a discrete element model of the SRM is established, and the influence of rock content on coordination number and mesostructure evolution of the SRM is analyzed. The results show that in SRM materials, the increase of crushed rock changes the mesostructure of the SRM material. With the increase of rock content, the internal contact force changes from “between soil and rock” to “between rocks”, and the skeleton formed in the rocks gradually develops overall stiffness. Under the condition of low stress, the anisotropy of the SRM material is mainly caused by the shape and grade distribution of crushed rock. The induced anisotropy caused by the change of stress state has little effect on its mechanical behavior, which may lead to the greater dispersion of multiple SRM test results.

Factors affecting red-osier dogwood seed germination

1992 ◽  
Vol 70 (5) ◽  
pp. 1012-1016 ◽  
Author(s):  
S. N. Acharya ◽  
C. B. Chu ◽  
R. Hermesh ◽  
G. B. Schaalje
Keyword(s):  
Seed Germination ◽  
Germination Percentage ◽  
Collection Site ◽  
Moisture Condition ◽  
Seed Formation ◽  
Factors Affecting ◽  
Year Effect ◽  
Wide Range ◽  
Cornus Stolonifera ◽  
Moisture Conditions

Seeds from 55 populations of native Alberta red-osier dogwood (Cornus stolonifera Michx.) were collected over 2 years (1984 and 1985) to determine the range of variability for seed germination and the effect of ecoregion and moisture conditions in the collection sites on this trait. Each year the unscarified seeds were stored at 3 °C for 30 days, stratified at 3 °C for an additional 30 days and then incubated on an 8 h light: 16 h dark cycle at a temperature of 25:10 °C (light:dark) for germination. A wide range of germination percentages was observed among populations collected in any 1 year. However, the variability was not due to the ecoregion or moisture condition of the collection site. Germination percentage of populations collected in 1984 and 1985 formed five and seven groups, respectively. A study involving eight sites that were common to 1984, 1985, and 1986 revealed a significant effect of population on seed germination. This population effect was not obscured by the combined effects of year, precipitation, temperature, and seed size. The year effect was significant only when population was used as a covariate. Precipitation during seed formation significantly influenced germination performance even after adjustments were made for population and year. Seed germination in red-osier dogwood appears to be influenced by the population from which the seeds are collected and by yearly environmental fluctuations. Therefore, germination studies in this species must include seeds from diverse populations collected over several years. Key words: red-osier dogwood, Cornus stolonifera Michx., germination, population, environment.

scholarly journals The influence of concrete substrate moisture condition on the tensile pull-off strength of protective coatings

2018 ◽  
Vol 199 ◽  
pp. 07016
Author(s):  
Sean Kay ◽  
Hans Beushausen
Keyword(s):  
Bond Strength ◽  
Protective Coatings ◽  
Surface Coatings ◽  
Moisture Condition ◽  
Coating Application ◽  
Substrate Saturation ◽  
Coating Durability ◽  
Substrate Moisture ◽  
Moisture Conditions

A range of different surface coatings are available for the protection of concrete surfaces, typically aimed at reducing the ingress of deleterious substances into the concrete and providing adequate aesthetic appeal on patch-repaired elements. The coating systems are usually of high material quality and perform well when applied and maintained correctly. The long-term success of protective surface coatings is largely a function of application procedures. In particular, coating durability with regards to bond strength and crack resistance is dependent on the preparation of the concrete substrate prior to coating application. This research gives insight into the effects a sound, clean and profiled concrete substrate that is subjected to different moisture conditions has on coating bond strength. The influence of three different methods to precondition concrete substrates on the tensile pull-off strength of two commercial coatings, applied to substrate concrete with various strengths was investigated. The moisture condition was found to have a significant influence on the pull-off strength of the coatings, higher degrees of substrate saturation typically resulting in higher strengths. Similarly, with increasing substrate moisture content, the failure mode increasingly shifted towards substrate cohesion failure.

Organizational Performance Framework

2015 ◽  
Vol 2 (4) ◽  
pp. 52-64
Author(s):  
Susheel Chhabra
Keyword(s):  
Regression Analysis ◽  
Organizational Performance ◽  
Research Study ◽  
Linear Regression Analysis ◽  
Organizational Settings ◽  
Government Services ◽  
Performance Framework ◽  
Efficiency And Effectiveness ◽  
Log Linear ◽  
Citizen Service

The research study proposes an organizational performance framework of Haryana Government departments involved in providing e-Government services through citizen service centers (CSCs). The objective of this framework is to suggest dimensions which need improvement for enhancing organizational performance. This will help to improve efficiency and effectiveness in providing services to citizens through CSCs. The organizational performance framework has been suggested using responses collected from 150 government departments. A log linear regression analysis is used to develop the framework. The framework can be used as a template for Government departments in similar other organizational settings.

E-Government Organizational Performance Framework

2010 ◽  
pp. 144-165
Author(s):  
Susheel Chhabra ◽  
Mahadeo Jaiswal
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Organizational Performance ◽  
State Government ◽  
Linear Regression Analysis ◽  
Performance Framework ◽  
Efficiency And Effectiveness ◽  
Enhance Efficiency ◽  
Log Linear

The objective of this chapter is to design an e-government organizational performance framework and to suggest ICTs solutions through a case study of Haryana state government in India so as to enhance efficiency and effectiveness of services provided to citizens. The framework is suggested using responses collected from 150 government departments. The ICTs solutions were validated by data collected from 90 e-government experts. A log linear regression analysis is used to develop the framework. The framework with minor modifications can be developed for similar other e-government settings.

scholarly journals Two-Parameter Modified Ridge-Type M-Estimator for Linear Regression Model

2020 ◽  
Vol 2020 ◽  
pp. 1-24
Author(s):  
Adewale F. Lukman ◽  
Kayode Ayinde ◽  
B. M. Golam Kibria ◽  
Segun L. Jegede
Keyword(s):  
Monte Carlo Simulation ◽  
Linear Regression ◽  
Regression Model ◽  
Linear Regression Model ◽  
Linear Regression Analysis ◽  
Ordinary Least Squares ◽  
M Estimator ◽  
Ordinary Least Squares Estimator ◽  
General Linear Regression Model ◽  
Two Parameter

The general linear regression model has been one of the most frequently used models over the years, with the ordinary least squares estimator (OLS) used to estimate its parameter. The problems of the OLS estimator for linear regression analysis include that of multicollinearity and outliers, which lead to unfavourable results. This study proposed a two-parameter ridge-type modified M-estimator (RTMME) based on the M-estimator to deal with the combined problem resulting from multicollinearity and outliers. Through theoretical proofs, Monte Carlo simulation, and a numerical example, the proposed estimator outperforms the modified ridge-type estimator and some other considered existing estimators.

scholarly journals Trends in Suicide Mortality by Method from 1979 to 2016 in Japan

2019 ◽  
Vol 16 (10) ◽  
pp. 1794 ◽  
Author(s):  
Bibha Dhungel ◽  
Maaya Kita Sugai ◽  
Stuart Gilmour
Keyword(s):  
Linear Regression ◽  
Linear Regression Analysis ◽  
Health Concern ◽  
Suicide Mortality ◽  
Registration System ◽  
Suicide Rates ◽  
Vital Registration System ◽  
Using Data ◽  
Age Adjusted Rates ◽  
Log Linear

Suicide is a major public health concern in Japan. This study aimed to characterize the trends in suicide mortality in Japan by method since 1979. Using data from the Japan vital registration system, we calculated age-standardized rates of suicide mortality separately by sex and method. We conducted a log-linear regression of suicide mortality rates separately by sex, and linear regression analysis of the proportion of deaths due to hanging, including a test for change in level and trend in 1998. While crude suicide rates were static over the time period, age-adjusted rates declined. The significant increase in suicide mortality in 1998 was primarily driven by large changes in the rate of hanging, with suicide deaths after 1998 having 36.7% higher odds of being due to hanging for men (95% CI: 16.3–60.8%), and 21.9% higher odds of being due to hanging for women (95% CI: 9.2–35.9%). Hanging has become an increasingly important method for committing suicide over the past 40 years, and although suicide rates have been declining continuously over this time, more effort is needed to prevent hanging and address the potential cultural drivers of suicide if the rate is to continue to decline in the future.

Study on Correction Method of Subgrade Modulus Based on FWD

2013 ◽  
Vol 579-580 ◽  
pp. 862-865
Author(s):  
Xiao Hua Luo ◽  
Qing Yang ◽  
Xin Qiu
Keyword(s):  
Resilient Modulus ◽  
Implementation Process ◽  
Correction Method ◽  
Deformation Analysis ◽  
Test Results ◽  
Moisture Condition ◽  
Back Calculation ◽  
The Mean ◽  
Subgrade Modulus ◽  
New Perspective

In order to calibrate subgrade back calculation modulus, the correction method of subgrade back calculation modulus was put forward based on theoretical analysis and indoor/outdoor experiments, and the detailed implementation process was analyzed combined the latest results of subgrade dynamic modulus and subgrade moisture forecast. The results show that the equivalent resilient modulus of subgrade simultaneously consider subgrade material moisture condition and stress dependency and the forecast equation has higher correlation. The ratio of the loading plate test results to the predicted results ranges from 0.25 to 0.4 and the mean is 0.32, which conforms to the requirements of AASHTO normal value. Utilizing the scale factor 0.65 to calibrate subgrade back calculation modulus is viable and validated. The results provides a new perspective and approach for deformation analysis of subgrade structure. As well, the established method makes up the defect that can't reflect the effect of moisture and stress on equivalent resilient modulus of subgrade.

Added Cost and Time Spent by Patients With History of Abuse in Florida Emergency Departments

2020 ◽  
Vol 35 (5) ◽  
pp. 741-750
Author(s):  
Natasha Kurji ◽  
Etienne E. Pracht ◽  
Barbara Langland-Orban ◽  
Kathleen Pracht
Keyword(s):  
Sexual Abuse ◽  
Interpersonal Violence ◽  
Healthcare Costs ◽  
Negative Binomial ◽  
Linear Regression Analysis ◽  
Physical And Mental Health ◽  
For Profit ◽  
Visit Duration ◽  
History Of ◽  
Log Linear

Interpersonal violence is known to lead to both short- and long-term health effects. Victims of sexual abuse tend to have higher healthcare costs and higher rates of physical and mental health issues than nonvictims. In this study, we investigate whether the comorbidity of mental illness and a personal history of adult physical and sexual abuse (HAPSA) results in higher healthcare costs and length of emergency department (ED) stay among Florida residents. A Negative Binomial and Log-Linear Regression Analysis suggest increased ED visit duration for those with a history of abuse, Hispanics, the uninsured, and those with multiple comorbidities. In addition, increased costs were found to be associated with White race, the uninsured, those with multiple comorbidities, and the facility type (for-profit hospitals).

Seasonal Variation of Backcalculated Subgrade Moduli

1997 ◽  
Vol 1577 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Bing Long ◽  
Mustaque Hossain ◽  
Andrew J. Gisi
Keyword(s):  
Seasonal Variation ◽  
Moisture Content ◽  
Temperature Effect ◽  
Resilient Modulus ◽  
Natural Soil ◽  
Temperature Regimes ◽  
Almost All ◽  
Moisture Conditions ◽  
Falling Weight ◽  
And Behavior

Seasonal variations in pavement material properties and behavior due to variations in temperature and moisture conditions are known to affect the structural performance of pavement. Temperature, subgrade moisture content, and falling weight deflectometer (FWD) deflection data were collected monthly on four asphalt pavement test sections for a year. Subgrade moduli were backcalculated using the elastic layer theory with two calculation schemes and pavement models. Backcalculation of subgrade moduli by subdividing the subgrade into a compacted subgrade layer and a natural soil subgrade layer resulted in compacted subgrade moduli that are more sensitive to the seasonal variation for all sites. It was found that for almost all sites, the patterns of subgrade response, in terms of subgrade moduli versus subgrade moisture content, simulated sine-shaped forms signifying a temperature effect. The temperature effect was confirmed by the strong correlation between backcalculated subgrade moduli and pavement surface temperature during FWD tests. The lowest backcalculated subgrade moduli were obtained for two sections during months when asphalt surface temperatures were excessively high (greater than 40°C). Both backcalculation schemes showed similar trends in variation of subgrade moduli over seasons. When the AASHTO relative damage concept was used to compute the effective roadbed soil resilient modulus for design, similar values were found for both schemes for most of the sites. The minimum frequency of FWD testing to capture the seasonal variation of subgrade was found to be three tests per year, or testing every fourth month, assuming that unusually high temperature regimes could be avoided.

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