The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

/pdf/the-environmental-protection-agency-3gx4opzrjm.pdf

The Environmental Protection Agency

Artificial neural networks (ANNs) constitute a class of flexible nonlinear models designed to mimic biological neural systems. In this entry, we introduce ANN using familiar econometric terminology and provide an overview of ANN modeling approach and its implementation methods. † Correspondence: Chung-Ming Kuan, Institute of Economics, Academia Sinica, 128 Academia Road, Sec. 2, Taipei 115, Taiwan; ckuan@econ.sinica.edu.tw. †† I would like to express my sincere gratitude to the editor, Professor Steven Durlauf, for his patience and constructive comments on early drafts of this entry. I also thank Shih-Hsun Hsu and Yu-Lieh Huang for very helpful suggestions. The remaining errors are all mine.

Artificial neural networks

Highway Capacity Manual改訂の動向--テイラ-教授の講演より

Dynamics of structures

Ground penetrating radar (GPR) technology has been used to assess pavement performance and structure for the past 30 years in a variety of ways. Results show that GPR works well for some situations but not as well for others. It is not currently used on a routine basis by the Departments of Transportation (DOTs) in the U.S. mainly because of difficulties encountered while interpreting GPR data. These difficulties are generally attributed to the fact that the GPR reflected signals that are collected depend largely on the a priori unknown dielectric properties of the structural materials. Additional difficulties arise from the fact that physically GPR cannot detect layers unless they have sufficiently dissimilar dielectric constants. In practice, GPR has been used primarily for pavement layer thickness estimation and moisture accumulation localization within the pavement layers. To improve GPR prediction capabilities, different data processing techniques have been developed that use the GPR reflected signal to estimate the dielectric properties of surveyed structures, thus determining their thicknesses. Other signal processing techniques have also been used successfully to enhance the quality of the GPR signal in order to increase the accuracy of the data interpretation results. For the covering abstract see ITRD E122906.

Measuring layer thicknesses with gpr - theory to practice

In recent years, the need for sealants in rigid pavement joints has become debatable, partly because of the unpredictable field performance of joint sealants. This inability to predict sealant performance stems from the fact that there is no laboratory evaluation method that accurately simulates field traffic and environmental loading conditions. A laboratory testing method was developed to predict the performance of rigid-pavement joint sealants. A research team at Virginia Tech designed a fixture that allows the evaluation of joint sealants under cyclic shear and static horizontal deflections. Shear deflection simulates vehicular loading, and horizontal deflection simulates expansion and contraction of concrete slabs due to temperature variation. Concrete specimens were prepared at a typical water-to-cement ratio of 0.45. Two aggregate types were used in the concrete mixes to evaluate the effect of aggregate type on sealant performance. Two commercially available sealants were investigated in the study....

Method To Evaluate Rigid-Pavement Joint Sealant Under Cyclic Shear and Constant Horizontal Deflections

How Do Geosynthetics Improve Pavement's Performance

In recent years, increased use of recycled asphalt materials (RAP) has created a need for softer binders to compensate stiffer binder coming from RAP. Economic alternatives, like recycled oils and proprietary bio-based oils, can be potential modifiers that will reduce the dependence on petroleum-based alternatives. However, there is limited information on the long-term rheological performance of binders modified with proprietary modifiers. These modifiers are chemically complex and their interaction with binders further complicates the binder chemistry. Therefore, the objective of this study was to evaluate the impact of modifier chemistry on modified binders’ long-term cracking potential. A base binder of Superpave Performance Grade (PG) 64-22 was used to develop PG 58-28 binder using six different modifiers. An unmodified PG 58-28 was included for a comparative analysis. A few modified binders rheologically outperformed the base binder and others performed similarly. The modifier derived from recycled engine oil showed the worst performance. Chemical analysis indicated that the best performing modified binders had significant amounts of nitrogen in the form of amines. On the other hand, poor performing modified binder had traces of sulfur. Additionally, modifiers with lower average molecular weights appeared to have a positive impact on the performance of aged binders.

https://www.mdpi.com/2076-3417/10/9/3249/pdf

Effect of Chemical Composition of Bio- and Petroleum-Based Modifiers on Asphalt Binder Rheology

This study was undertaken to investigate the engineering properties of a river pea gravel and to develop a model that can be applied to predict the stopping distance of runaway trucks in arrester b...

Imad L. Al-Qadi

Papers

Measuring layer thicknesses with gpr - theory to practice

Method To Evaluate Rigid-Pavement Joint Sealant Under Cyclic Shear and Constant Horizontal Deflections

How Do Geosynthetics Improve Pavement's Performance

Effect of Chemical Composition of Bio- and Petroleum-Based Modifiers on Asphalt Binder Rheology

Use of Gravel Properties to Develop Arrester Bed Stopping Model