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1

Field performance of geosynthetic reinforced pavements over expansive clay subgrades  

E-print Network

Field performance of geosynthetic reinforced pavements over expansive clay subgrades Zornberg, J, The University of Texas, Austin, USA 78712 Keywords: reinforced pavements; expansive soils; geogrids; geotextiles cracks on the pavement structures. Traditionally the problems related to flexible pavements over

Zornberg, Jorge G.

2

PORTLAND CEMENT CONCRETE PAVEMENT FOR FLEXIBLE OVER RIGID COMPOSITE PAVEMENTS (Tollway)  

E-print Network

PORTLAND CEMENT CONCRETE PAVEMENT FOR FLEXIBLE OVER RIGID COMPOSITE PAVEMENTS (Tollway) Effective portland cement concrete for special applications to composite pavements as shown and described. Developing concrete mix design(s) that meets the performance requirements for the intended pavement; 4

3

Accounting for the effects of rehabilitation actions on the reliability of flexible pavements: performance modeling and optimization  

E-print Network

-Chairs of Committee, Ivan Damnjanovic Paolo Gardoni Committee Member, Thomas Wehrly Head of Department, David V. Rosowsky August 2008 Major Subject: Civil Engineering iii? ? ABSTRACT Accounting for the Effects of Rehabilitation Actions... on the Reliability of Flexible Pavements: Performance Modeling and Optimization. (August 2008) Vighnesh Prakash Deshpande, B.E., Sardar Patel College of Engineering, Mumbai Co-Chairs of Advisory Committee: Dr. Ivan Damnjanovic Dr. Paolo Gardoni A performance...

Deshpande, Vighnesh Prakash

2009-05-15

4

Performance of a movable flexible pipe-encapsulated FBG sensor developed for shape monitoring of multi-layered pavement structure  

NASA Astrophysics Data System (ADS)

The large span and heterogeneous components of multi-layered pavement structure usually bring about stochastic damage, and many modern approaches, such as ground penetrating radar, integral imaging and optical fiber sensing technology, have been employed to detect the degeneration mechanism. Restricted by the cost and universality, novel elements for pavement monitoring are in high demand. Optical fiber sensing technology for high sensitivity, long stability, anti-corrosion and resistance to water erosion then is considered. Therefore, a movable FBG sensor located in flexible pipe is developed, which has long stroke inside inner wall of the hollow pipe, and a full-scale shape of the structure could be sketched just with one FBG. Theoretical and experimental methods about establishing the relationship between wavelength variable and curvature have been provided, and function about reconfiguring the coordinate is converted to a mathematic question. Move over, transfer error modification has been taken into account for modify related error. Multi-layered pavement model embedded with this sensor will be accomplished to inspect its performance in later work. The work in the paper affords a feasible method for shape monitoring and would be potentially valuable for the maintenance and inverse design of pavement structure.

Wang, Huaping; Liu, Wanqiu; Zhou, Zhi

2014-03-01

5

Adaptive prediction of pavement performance  

E-print Network

. This adjustment is considered for each category of pavement distress separately. The computer program has been tested using field data from Long Term Pavement Performance Project (LTPP) and TxDOT Pavement Management Information System (PMIS) data collected...

Zulyaminayn, Mohammed

2012-06-07

6

Effects of temperature and water on pavement performance  

SciTech Connect

The 12 papers in the report deal with the following areas: procedures for estimation of asphalt-concrete pavement moduli at in-situ temperatures; stress caused by temperature gradient in portland-cement concrete pavements; characterizing temperature effects for pavement analysis and design; temperature response of concrete pavements; an examination of environmental versus load effects on pavements; moisture in portland-cement concrete; effect of rainfall on the performance of continuously reinforced concrete pavements in Texas; effect of moisture on the structural performance of a crushed-limestone road base; water-induced distress in flexible pavement in a wet tropical climate; an evaluation of design high-water clearances for pavements; economic impact of pavement subsurface drainage; use of open-graded, free-draining layers in pavement systems; a national synthesis report.

Badu-Tweneboah, K.; Tia, M.; Ruth, B.E.; Richardson, J.M.; Armaghani, J.M.

1987-01-01

7

Evaluation of tire pressure, tire construction, axle configuration, and axle load on flexible pavement performance  

E-print Network

loading among axles, and high tire pressures. The tire is represented as a uniformly loaded circular area with contact pressure assumed as 9OX, of inflation pressure. A modified Chevron N-layer model was used to calculate pavement stresses and strains...

Jamy, Ahmad Najeeb

1991-01-01

8

Analysis and design optimization of flexible pavement  

SciTech Connect

A project-level optimization approach was developed to minimize total pavement cost within an analysis period. Using this approach, the designer is able to select the optimum initial pavement thickness, overlay thickness, and overlay timing. The model in this approach is capable of predicting both pavement performance and condition in terms of roughness, fatigue cracking, and rutting. The developed model combines the American Association of State Highway and Transportation Officials (AASHTO) design procedure and the mechanistic multilayer elastic solution. The Optimization for Pavement Analysis (OPA) computer program was developed using the prescribed approach. The OPA program incorporates the AASHTO equations, the multilayer elastic system ELSYM5 model, and the nonlinear dynamic programming optimization technique. The program is PC-based and can run in either a Windows 3.1 or a Windows 95 environment. Using the OPA program, a typical pavement section was analyzed under different traffic volumes and material properties. The optimum design strategy that produces the minimum total pavement cost in each case was determined. The initial construction cost, overlay cost, highway user cost, and total pavement cost were also calculated. The methodology developed during this research should lead to more cost-effective pavements for agencies adopting the recommended analysis methods.

Mamlouk, M.S.; Zaniewski, J.P.; He, W.

2000-04-01

9

Structural response of LVR flexible pavements at Mn/ROAD project  

SciTech Connect

Pavement surface deflection basins provide valuable information for the structural evaluation of flexible pavements. Surface deflection measurements are rapid, inexpensive, and nondestructive and are used frequently as an indicator of pavement structural capability and performance potential. In this study, falling weight deflectometer testing results on the conventional flexible pavements (asphalt concrete surface, granular base/subbase) and aggregate-surface/surface-treated test sections in the low-volume road loop at the Minnesota Road Research Project (Mn/ROAD) were analyzed to evaluate the effect of granular material quality on the pavement structural response. Asphalt concrete (AC) modulus and subgrade ``break-point`` modulus were back-calculated using algorithms previously developed at the University of Illinois. The surface deflections were normalized to the same AC modulus and subgrade modulus. The analyses show a limited effect of granular material quality on the pavement deflection response in the case of conventional flexible pavements. Because of higher granular layer stresses, the granular material quality effects on the pavement surface deflection response of surface-treated/aggregate-surface pavements are significant. Increased AC thickness reduces the effect of granular base quality on the pavement deflection response.

Garg, N.; Thompson, M.R. [Univ. of Illinois, Urbana, IL (United States). Dept. of Civil Engineering] [Univ. of Illinois, Urbana, IL (United States). Dept. of Civil Engineering

1999-05-01

10

DETERIORATION FORECASTING IN FLEXIBLE PAVEMENTS DUE TO FLOODS AND SNOW STORMS  

E-print Network

DETERIORATION FORECASTING IN FLEXIBLE PAVEMENTS DUE TO FLOODS AND SNOW STORMS Salar Shahini.birken@neu.edu, 4 mi.wang@neu.edu ABSTRACT Roadway agencies and state DOTs utilize Pavement Management Systems (PMS process of pavements is an integral part of any Pavement Management System. As pavement condition grows

Boyer, Edmond

11

Minimizing Distress on Flexible Pavements Using Variable Tire Pressure  

Microsoft Academic Search

The potential of variable tire pressure technology to minimize distress on flexible pavements with thin asphalt surfacing layers and peat soil subgrade was evaluated using in-situ stress-strain data. Pavement interfacial strains and corresponding subgrade stresses imposed by a three-axle truck were measured and used to estimate the fatigue life of the surfacing layer. Three levels of truck wheel loads in

Philip M. O. Owende; Anton M. Hartman; Shane M. Ward; Michael D. Gilchrist; Michael J. O'Mahony

2001-01-01

12

Full scale tests on grid reinforced flexible pavements on the French fatigue carrousel  

E-print Network

Full scale tests on grid reinforced flexible pavements on the French fatigue carrousel Pierre the long term life of grid reinforced pavements. This paper describes a full scale experiment carried out on the large pavement fatigue carrousel of IFSTTAR, to test simultaneously 3 pavement sections with different

Boyer, Edmond

13

The impact of material characteristics on tire pavement interaction noise for flexible pavements  

NASA Astrophysics Data System (ADS)

Noise pollution has recently been one of the growing problems all over the world. While there are many sources of the noise, traffic noise is the main contributor to the total environmental noise. Although there are different sources for traffic noise, the tire pavement interaction noise is the most dominant component within most city and highway limits. One of the ways to reduce the tire pavement noise is to improve the material characteristics of the pavements such that they produce less noise. In this study, the relationship between basic material characteristics (e.g., Hot Mix Asphalt (HMA) volumetrics) and sound generation and absorption characteristics of flexible pavements was investigated. In addition, the effect of linear visco-elastic properties (e.g., dynamic modulus (|E*|) and phase angle (delta)) on sound absorption was studied. In order to focus only on impact of material characteristics and overshadow the effect of surface texture, a novel laboratory tire pavement noise measurement simulator (TIPANOS) was developed. The statistical analysis results showed that although the individual material characteristics do not have appreciable influence on sound absorption, there is a significant correlation between sound pressure levels (SPL) and combination of several material and linear visco-elastic parameters.

Kocak, Salih

14

Pavement performance modelling with an auto-regression approach  

Microsoft Academic Search

In this paper, an auto-regression method is applied to pavement performance modelling to improve the predictive accuracy of predictions when there are only limited or incomplete data available. Using age and past measured conditions as independent variables, the average trend within a pavement group is captured by a ‘global’ function shared by all pavements, while any pavement-specific effects are reflected

Z. Luo

2011-01-01

15

Viscoelastic functionally graded finite element method with recursive time integration and applications to flexible pavements  

E-print Network

and applications to flexible pavements Eshan V. Dave1,,,, Glaucio H. Paulino2,§ and William G. Buttlar2,¶, 1 for modeling geotechnical and pavement structures exhibiting significant non-homogeneity. Property gradients pavements. Investigation of time-dependent behavior combined with functionally graded property gradation can

Paulino, Glaucio H.

16

INTRODUCTION Pavement preservation is an approach in enhancing pavement performance using a set of practices that extends the life  

E-print Network

INTRODUCTION Pavement preservation is an approach in enhancing pavement performance using a set of practices that extends the life of the pavement and improves safety and ride quality. According to theWorld Bank's Pavement Deterioration Model, the cost of returning a pavement to good condition after

Stephens, Jacqueline

17

Porous Pavement in Cold Climates Part: Performance and Cost  

E-print Network

Porous Pavement in Cold Climates Part: Performance and Cost Onondaga Environmental Institute 17 #12;Overview 1. Hydrology of Permeable Pavements 2. Water Quality Performance 3. Hydraulic Performance However, a large number of installations STILL continue to be sub-standard 4 #12;Porous Pavement Design

18

A numerical model for flexible pavements rut depth evolution with time  

NASA Astrophysics Data System (ADS)

A simplified method has been developed for the finite elements modelling of flexible pavements rut depth evolution with time. This method is based on the shakedown theory established by Zarka for metallic structures. The yield surface of Drucker-Prager and the plastic potential of Von Mises have been used. The simplified method determines straightforwardly the purely elastic state or the elastic shakedown state or the plastic shakedown state. The calibration of the simplified method with two unbound granular materials for roads under repeated loads triaxial tests, is explained. Then, a finite elements modelling of a flexible pavement has been carried out. Calculations of 2D and 3D have been performed and rut depth evolutions with time are shown, which underline the capabilities of the model to take into account the accumulation of plastic strains along the loading cycles. Copyright

Allou, Fatima; Chazallon, Cyrille; Hornych, Pierre

2007-01-01

19

Performance of continuously reinforced concrete pavements: Volume 6 -- CRC pavement design, construction, and performance. Final report, August 1990--December 1994  

SciTech Connect

This report is one of a series of reports prepared as part of a recent study sponsored by the Federal Highway Administration (FHWA) aimed at updating the state-of-the-art of the design, construction, maintenance, and rehabilitation of continuous reinforced concrete (CRC) pavements. The scope of work of the FHWA study included the following: (1) Conduct of a literature review and preparation of an annotated bibliography on CRC pavements and CRC overlays. (2) Conduct of a field investigation and laboratory testing related to 23 existing in-service pavement sections. This was done to evaluate the effect of various design features on CRC pavement performance, to identify any design or construction related problems, and to recommend procedures to improve CRC pavement technology. (3) Evaluation of the effectiveness of various maintenance and rehabilitation strategies for CRC pavements. (4) Preparation of a Summary Report on the current state of the practice for CRC pavements. Each of the above four items is addressed in a separate report. The following reports have been prepared under this study: Performance of CRC Pavements. Volume 1: Summary of Practice and Annotated Bibliography. Volume 2: Field Investigation of CRC Pavements. Volume 3: Analysis and Evaluation of Field Test Data. Volume 4: Resurfacing for CRC Pavements. Volume 5: Maintenance and Repair of CRC Pavements. Volume 6: CRC Pavement Design, Construction, and Performance. Volume 7: Summary. This report is Volume 6 in the series.

Zollinger, D.G.; Buch, N.; Xin, D.; Soares, J.

1999-02-01

20

Impact of the variation in dynamic vehicle load on flexible pavement responses  

NASA Astrophysics Data System (ADS)

The purpose of this research was to evaluate the dynamic variation in asphalt pavement critical responses due to dynamic tire load variations. An attempt was also made to develop generalized regression equations to predict the dynamic response variation in flexible pavement under various dynamic load conditions. The study used an extensive database of computed pavement response histories for five different types of sites (smooth, rough, medium rough, very rough and severely rough), two different asphalt pavement structures (thin and thick) at two temperatures (70 °F and 104 °F), subjected to a tandem axle dual tire at three speeds 25, 37 and 50 mph (40, 60 and 80 km/h). All pavement responses were determined using the 3D-Move Analysis program (Version 1.2) developed by University of Nevada, Reno. A new term called Dynamic Response Coefficient (DRC) was introduced in this study to address the variation in critical pavement responses due to dynamic loads as traditionally measured by the Dynamic Load Coefficient (DLC). While DLC represents the additional varying component of the tire load, DRC represents the additional varying component of the response value (standard deviation divided by mean response). In this study, DRC was compared with DLC for five different sites based on the roughness condition of the sites. Previous studies showed that DLC varies with vehicle speed and suspension types, and assumes a constant value for the whole pavement structure (lateral and vertical directions). On the other hand, in this study, DRC was found to be significantly varied with the asphalt pavement and function of pavement structure, road roughness conditions, temperatures, vehicle speeds, suspension types, and locations of the point of interest in the pavement. A major contribution of the study is that the variation of pavement responses due to dynamic load in a flexible pavement system can be predicted with generalized regression equations. Fitting parameters (R2) in the rage of 0.60 to 0.87 were observed the DRC predictive equations. In addition, verification of those generalized equations was evaluated using different sets of asphalt pavement structures and pavement materials. The differences between calculated and predicted values were found to be within +/-20% for the maximum tensile strain and +/-30% for the maximum compressive strain in the asphalt layer.

Ahsanuzzaman, Md

21

Fuzzy optimization BP neural network model for pavement performance assessment  

Microsoft Academic Search

This paper discussed the use of fuzzy optimization BP neural network as a management tool for the maintenance of expressway pavement. The algorithm was applied to model pavement performance evaluation, successful in accurately and quickly capturing the high nonlinear characteristics between objective practical data and subjective synthetic evaluations, avoided the neural network activation function's defects of unclear physical meanings. A

Yan Liu; Min Sun

2007-01-01

22

Performance-Based Concrete Pavement Mix Design System Performance-Based Design Guide for New and Rehabilitated  

E-print Network

Strategic Research Plan #12;· Performance-Based Concrete Pavement Mix Design System · Performance-Based Design Guide for New and Rehabilitated Concrete Pavements · High-Speed Nondestructive Testing Pavements · High-Speed Concrete Pavement Rehabilitation and Construction · Concrete Pavement Business

23

Two-dimensional finite element analysis of flexible pavements considering non-linear materials and interface conditions  

SciTech Connect

Two-dimensional finite element analysis of a flexible pavement section was performed using a special purpose finite element method (FEM) code and a commercial general purpose FEM. Viscoelastic, plastic, and hyperbolic-elastic materials models were used in the analyses. One-dimensional interface elements were used in both analyses. The results of the analyses were compared with predictions using current evaluation/design models.

Gonzales, C.R. [Army Engineer Waterways Experiment Station, Vicksburg, MS (United States); Salami, M.R. [North Carolina A and T State Univ., Greensboro, NC (United States)

1995-06-01

24

Use of Falling Weight Deflectometer Data to Quantify the Relative Performance of Reinforced Pavement Sections  

E-print Network

Pavement Sections Joshi, R.V.1 , S.M. ASCE and Zornberg J.G.2 , PhD., P.E, A.M. ASCE 1 Research Assistant in Grimes County, Texas. The pavement involves eight different experimental cross sections including control the flexible pavement to environmental loading. The objective of this paper is to characterize the possible

Zornberg, Jorge G.

25

Improving Rutting Resistance of Pavement Structures Using Geosynthetics: An Overview  

PubMed Central

A pavement structure consists of several layers for the primary purpose of transmitting and distributing traffic loads to the subgrade. Rutting is one form of pavement distresses that may influence the performance of road pavements. Geosynthetics is one type of synthetic materials utilized for improving the performance of pavements against rutting. Various studies have been conducted on using different geosynthetic materials in pavement structures by different researchers. One of the practices is a reinforcing material in asphalt pavements. This paper intends to present and discuss the discoveries from some of the studies on utilizing geosynthetics in flexible pavements as reinforcement against permanent deformation (rutting). PMID:24526919

Karim, Mohamed Rehan; Khodaii, Ali; Almasi, Mohammad Hadi

2014-01-01

26

Improving rutting resistance of pavement structures using geosynthetics: an overview.  

PubMed

A pavement structure consists of several layers for the primary purpose of transmitting and distributing traffic loads to the subgrade. Rutting is one form of pavement distresses that may influence the performance of road pavements. Geosynthetics is one type of synthetic materials utilized for improving the performance of pavements against rutting. Various studies have been conducted on using different geosynthetic materials in pavement structures by different researchers. One of the practices is a reinforcing material in asphalt pavements. This paper intends to present and discuss the discoveries from some of the studies on utilizing geosynthetics in flexible pavements as reinforcement against permanent deformation (rutting). PMID:24526919

Mirzapour Mounes, Sina; Karim, Mohamed Rehan; Khodaii, Ali; Almasi, Mohammad Hadi

2014-01-01

27

Relating tensile, bending, and shear test data of asphalt binders to pavement performance  

Microsoft Academic Search

Eight different asphalt binders representing a wide range of applications for pavement construction were tested in uniaxial tension, bending, and shear stresses. Theoretical analyses were performed in this study to convert the data from the three engineering tests to stiffness moduli for predicting pavement performance. At low temperatures, high asphalt stiffness may induce pavement thermal cracking; thus, the allowable maximum

J.-S. Chen; C.-J. Tsai

1998-01-01

28

Winter Performance and Maintenance of Porous Asphalt Pavements  

E-print Network

Winter Performance and Maintenance of Porous Asphalt Pavements Robert M. Roseen, Ph.D., P.E., D impacts for new development and reverse impacts in areas with redevelopment. #12;Porous Asphalt Design impacts for new development and reverse impacts in areas with redevelopment. Porous asphalt systems

29

The falling weight deflectometer (FWD) test is one of the most com-monly used tools for nondestructive evaluation of flexible pavements.  

E-print Network

for nondestructive evaluation of flexible pavements. Although the test is intrinsically dynamic, the state that the fore- going discrepancy may lead to systematic errors in the estimation of pavement moduli and extract the static pavement response from transient FWD records. With the filtered (i.e., zero

Guzina, Bojan

30

Geosynthetics in pavements: North American contributions Zornberg, J.G. & Gupta, R.  

E-print Network

Geosynthetics in pavements: North American contributions Zornberg, J.G. & Gupta, R. The University, pavement, design ABSTRACT: Geosynthetics have been used to reinforce the base layer of flexible pavement reinforcements can im- prove pavement performance, the specific conditions or mechanisms that enable and govern

Zornberg, Jorge G.

31

PAVEMENT PREDICTION PERFORMANCE MODELS AND RELATION WITH TRAFFIC FATALITIES AND INJURIES  

E-print Network

PAVEMENT PREDICTION PERFORMANCE MODELS AND RELATION WITH TRAFFIC FATALITIES AND INJURIES V. CEREZO.gothie@developpement-durable.gouv.fr ABSTRACT This paper presents some results of a study, which aimed at modelling pavement evolution, pavement characteristics and age. In a second part, non-linear regressions were used in view of obtaining

Boyer, Edmond

32

TRANSPORTATION RESEARCH RECORD 1574 Paper No. 971071 89 Performance of Rigid Pavements  

E-print Network

TRANSPORTATION RESEARCH RECORD 1574 Paper No. 971071 89 Performance of Rigid Pavements Containing designed and constructed rigid pavements containing recycled concrete aggregate (RCA). Success has been project did exhibit significantly more slab cracking in the recycled pavement than in the corresponding

Vandenbossche, Julie M.

33

An elastoplastic model based on the shakedown concept for flexible pavements unbound granular materials  

NASA Astrophysics Data System (ADS)

Nowadays, the problem of rutting of flexible pavements linked to permanent deformations occurring in the unbound layers is taken into account only by mechanistic empirical formulas. Finite element modelling of realistic boundary value problems with incremental rheological models will lead to unrealistic calculation time for large cycle numbers. The objective of the authors is to present a simplified model which can be used to model the flexible pavements rutting with the finite elements framework. This method is based on the shakedown theory developed by Zarka which is usually associated to materials like steels. It has been adapted for granular materials by introducing a yield surface taking into account the mean stress influence on the mechanical behaviour and a dependency of the hardening modulus with the stress state. The Drucker-Prager yield surface has been used with a non-associated flow rule. Comparisons with repeated load triaxial tests carried out on a subgrade soil have been done. These comparisons underline the capabilities of the model to take into account the cyclic behaviour of unbound materials for roads. Finally, a discussion, dealing with the use of the simplified method within a finite element modelling of a full-scale experiment, is presented.

Habiballah, Taha; Chazallon, Cyrille

2005-05-01

34

Experimental Study on Geocell-Reinforced Flexible Pavements with Recycled Asphalt Pavement (RAP) Bases under Cyclic Loading  

E-print Network

, it is estimated that U. S. production of asphalt pavement materials is around 500 million tons per years, including about 60 million tons of RAP - which transportation agencies reuse or recycle directly into pavements. In addition, agencies reuse or recycle... efforts to recover and reuse old asphalt paving materials in road construction were made in Nevada and Texas in 1974. RAP has been mostly used in hot or cold mix asphalt with virgin asphalt binder and aggregate. In addition, RAP has been used...

Acharya, Bhagaban

2011-12-31

35

Relating tensile, bending, and shear test data of asphalt binders to pavement performance  

Microsoft Academic Search

Eight different asphalt binders representing a wide range of applications for pavement construction were tested in uniaxial\\u000a tension, bending, and shear stresses. Theoretical analyses were performed in this study to convert the data from the three\\u000a engineering tests to stiffness moduli for predicting pavement performance. At low temperatures, high asphalt stiffness may\\u000a induce pavement thermal cracking; thus, the allowable maximum

J.-S. Chen; C.-J. Tsai

1998-01-01

36

1 INTRODUCTION Flexural fatigue is one of the main failure modes in asphalt mixtures and flexible pavement  

E-print Network

1 INTRODUCTION Flexural fatigue is one of the main failure modes in asphalt mixtures and flexible the asphalt pavement has viscoelastic behaviour, it recovers when the load is removed. At the end, France ABSTRACT: The mechanical characterisation of the asphalt concrete in terms of both the fa- tigue

Paris-Sud XI, Université de

37

Assessment of porous asphalt pavement performance: hydraulics and water quality  

NASA Astrophysics Data System (ADS)

The objective of this study is to focus on the water quality treatment and hydraulic performance of a porous asphalt pavement parking lot in Durham, New Hampshire. The site was constructed in October 2004 to assess the suitability of porous asphalt pavement for stormwater management in cold climates. The facility consists of a 4-inch asphalt open-graded friction course layer overlying a high porosity sand and gravel base. This base serves as a storage reservoir in-between storms that can slowly infiltrate groundwater. Details on the design, construction, and cost of the facility will be presented. The porous asphalt pavements is qualitatively monitored for signs of distress, especially those due to cold climate stresses like plowing, sanding, salting, and freeze-thaw cycles. Life cycle predictions are discussed. Surface infiltration rates are measured with a constant head device built specifically to test high infiltration capacity pavements. The test measures infiltration rates in a single 4-inch diameter column temporarily sealed to the pavement at its base. A surface inundation test, as described by Bean, is also conducted as a basis for comparison of results (Bean, 2004). These tests assess infiltration rates soon after installation, throughout the winter, during snowmelt, after a winter of salting, sanding, and plowing, and after vacuuming in the spring. Frost penetration into the subsurface reservoir is monitored with a frost gauge. Hydrologic effects of the system are evaluated. Water levels are monitored in the facility and in surrounding wells with continuously logging pressure transducers. The 6-inch underdrain pipe that conveys excess water in the subsurface reservoir to a riprap pad is also continuously monitored for flow. Since porous asphalt pavement systems infiltrate surface water into the subsurface, it is important to assess whether water quality treatment performance in the subsurface reservoir is adequate. The assumed influent water quality is derived from that which is entering the stormwater treatment system in the adjacent parking lot. Since the facility is new, parking has been less intensive here, and influent concentrations will be adjusted down accordingly. Several wells have been installed in and around the facility. Screened intervals are at two levels; in the reservoir and beneath the facility. One well in the facility is continually monitored for basic water quality parameters (temperature, specific conductivity, pH, dissolved oxygen) and level, and is also sampled with an automated refrigerated sampler. Grab samples are collected from the other wells as a basis for comparison. Water samples are collected during several storm events and during interstorm periods to assess water quality treatment performance. The samples are analyzed for nutrients, metals, petroleum hydrocarbons, and pathogens. The potential for leaching of pollutants from the asphalt binder will also be assessed during these storm events. Water quality treatment performance is compared to those of several other studies. Updates on spring 2005 data are also included in the presentation.

Briggs, J. F.; Ballestero, T. P.; Roseen, R. M.; Houle, J. J.

2005-05-01

38

Rebound and residual in situ pavement displacements measured during NAPTF performance testing  

Microsoft Academic Search

The FAA's National Airport Pavement Test Facility (NAPTF) was constructed to generate full-scale test data needed for the development of advanced airport pavement design procedures. In this paper, the comparative effects of six-wheel Boeing 777 (B777) and four-wheel Boeing 747 (B747) simulated landing gear loading on the multi-depth deflectometer (MDD) responses of two NAPTF low-strength subgrade flexible test sections are

Kasthurirangan Gopalakrishnan; Marshall R. Thompson

2007-01-01

39

Discussion on the Prediction Method of the Pavement Performance for Expressway  

Microsoft Academic Search

The empirical regression model was selected for forecasting the preventive maintenance time; the grey system theory was used to determine if pavements were fit for preventive maintenance. Combined with the instance, on the forecasting of the pavement performance for an expressway, the application of the grey system theory was introduced.

He Xiao-ming; Guan Peng; Hu Guo-xiang; Zhou Lin

2009-01-01

40

Statistical methods for pavement performance curve building, historical analysis, data sampling and storage. Final report, May 1997--July 1998  

SciTech Connect

The use of a pavement management system provides a state highway agency with the tools necessary to conduct a multi-year analysis of the maintenance and rehabilitation needs within the state based on both current needs and expected future conditions. In order to adequately predict future conditions, pavement performance models must be developed to reflect the deterioration trends of the agency`s pavements. At the time the SDDOT pavement management system was implemented in 1994, the Department developed a new condition rating system to evaluate the existing conditions of the state maintained pavements. At the same time, expert-based pavement performance models were developed to approximate the deterioration patterns of the highways based on pavement families (groupings of pavements with similar characteristics). A recommendation from that study (SD93-14) was to update the curves based on historical performance once sufficient data had been collected.

Zimmerman, K.A.; Bahulkar, A.M.

1998-08-01

41

Statistical methods for pavement performance curve building, historical analysis, data sampling and storage: Appendix D. Final report  

SciTech Connect

The technical memorandum is intended to discuss the detailed procedure required for carrying out the statistical analyses of historical pavement condition data for building pavement performance curves. This chapter assumes the availability of the historical data in a spreadsheet format (Microsoft{trademark} Excel) that has been retrieved from the master (pavement management system) database.

NONE

1998-08-01

42

Sensitivity analysis of flexible pavement response and AASHTO 2002 design guide for properties of unbound layers  

E-print Network

Data Used in the FEM Program (LIS: Linear Isotropic, NIS: Nonlinear Isotropic, NAN: Nonlinear Anisotropic, NIS: Nonlinear Isotropic) .............................................................................................27 4.1 Pavement...

Masad, Sanaa Ahmad

2004-09-30

43

High performance flexible heat pipes  

NASA Technical Reports Server (NTRS)

A Phase I SBIR NASA program for developing and demonstrating high-performance flexible heat pipes for use in the thermal management of spacecraft is examined. The program combines several technologies such as flexible screen arteries and high-performance circumferential distribution wicks within an envelope which is flexible in the adiabatic heat transport zone. The first six months of work during which the Phase I contract goal were met, are described. Consideration is given to the heat-pipe performance requirements. A preliminary evaluation shows that the power requirement for Phase II of the program is 30.5 kilowatt meters at an operating temperature from 0 to 100 C.

Shaubach, R. M.; Gernert, N. J.

1985-01-01

44

Contributions of performance-graded asphalt to low temperature cracking resistance of pavements. Final report  

SciTech Connect

The purpose of this research was to study and evaluate the role that asphalt cracking. As part of the Strategic Highway Research Program (SHRP) new specifications for asphalt binders were developed that are based on the performance of the material. The asphalt binder graded and specified according to these new performance-based specifications is called PG binder. These new specifications are commonly referred to as Superpave (Superior Performing Asphalt Pavement) binder specifications. A section of Interstate 64 in southern Indiana was experiencing severe low temperature cracking before it was reconstructed over the summers of 1995 and 1996. The binder used in the new pavement mixes was PG material. Dynamic Shear Rheometer (DSR) tests, Bending Beam Rheometer (BBR) tests, and viscosity tests were performed on this binder. Comparisons were made between test results obtained from the binders in the old pavement and the new pavement. All tests and comparisons were based on the Superpave binder specifications.

Loh, S.W.; Olek, J.

1999-05-01

45

AN IMPROVED DYNAMIC MODEL FOR THE STUDY OF A FLEXIBLE PAVEMENT  

E-print Network

-destructive tests (NDT) have become increasingly popular, for allowing pave- ment overlay designs to be based on the in situ conditions of a pavement structure. Among the array of NDT tests, standard methods are limited Weight De- ectometer (FWD) is the most popular for the NDT testing of exible pavements. The FWD (see Fig

Avignon et des Pays de Vaucluse, Université de

46

Performance Prediction of the NCAT Test Track Pavements Using Mechanistic Models  

NASA Astrophysics Data System (ADS)

In the pavement industry in the United States of America, there is an increasing desire to improve the pavement construction quality and life for new and rehabilitated pavements. In order to improve the quality of the pavements, the Federal Highway Administration (FHWA) has pursued a performance-related specification (PRS) for over 20 years. The goal of PRS is to provide material and construction (M/C) properties that correlate well with pavement performance. In order to improve upon the PRS projects developed in WesTrack (NCHRP 9-20) and the MEPDG-based PRS (NCHRP 9-22), a set of PRS tests and models are proposed to provide a critical link between pavement performance and M/C properties. The PRS testing is done using the asphalt mixture performance tester (AMPT). The proposed PRS focuses on rutting and fatigue cracking of asphalt mixtures. The mixtures are characterized for their stiffness, fatigue behavior, and rutting resistance using a dynamic modulus (|E*|) test, a fatigue test, and a triaxial stress sweep (TSS) test, respectively. Information from the fatigue test characterizes the simplified viscoelastic continuum damage (S-VECD) model. Once the stiffness is reduced to a certain level, the material develops macro-cracks and fails. The TSS test is used to characterize a viscoplastic (VP) model. The VP model allows the prediction of the rut depth beneath the center of the wheel. The VECD and VP models are used within a layered viscoelastic (LVE) pavement model to predict fatigue and rutting performance of pavements. The PRS is evaluated by comparing the predictions to the field performance at the NCAT pavement test track in Opelika, Alabama. The test track sections evaluated are part of the 2009 test cycle group experiment, which focused on WMA, high RAP (50%), and a combination of both. The fatigue evaluation shows that all sections would last at least 18 years at the same traffic rate. The sections do not show any cracking, suggesting the sections are well-built and a long life is possible. The rutting in the test track is also predicted. All the predicted rut depths are 2-4 mm higher than measured in the field, but the overall ranking of different pavement sections matches the ranking in the field quite well. Conclusions and recommendations for future research are drawn from the observations made from experimental results as well as performance prediction of NCAT pavement sections.

LaCroix, Andrew Thomas

47

Performance of concrete pavements containing recycled concrete aggregate. Interim report, October 1993-October 1996  

SciTech Connect

This interim report documents the field performance of nine concrete pavement projects that incorporate recycled concrete aggregate (RCA) in the construction of the pavement. Multiple sections were evaluated on many of the nine projects, due to perceived differences in performance levels or variations in pavement design (such as the use of virgin aggregate or the inclusion of dowel bars). All told, a total of 17 sections (of which 12 contain RCA) were subjected to an extensive field testing program, consisting of pavement condition surveys, drainage surveys, falling weight deflectometer (FWD) testing, coring, and serviceability assessments. A minimum of eight cores were retrieved from each section for laboratory evaluation of compressive strength, split tensile strength, dynamic elastic modulus, static elastic modulus, and thermal coefficient of expansion, as well as for volumetric surface testing and petrographic analyses.

Wade, M.J.; Cuttell, G.D.; Vandenbossche, J.M.; Yu, H.T.; Smith, K.D.

1997-03-01

48

Relating tensile, bending, and shear test data of asphalt binders to pavement performance  

SciTech Connect

Eight different asphalt binders representing a wide range of applications for pavement construction were tested in uniaxial tension, bending, and shear stresses. Theoretical analyses were performed in this study to covert the data from the three engineering tests to stiffness moduli for predicting pavement performance. At low temperatures, high asphalt stiffness may induce pavement thermal cracking; thus, the allowable maximum stiffness was set at 1,000 MPa. At high temperatures, low asphalt stiffness may lead to pavement rutting (ruts in the road); master curves were constructed to rank the potential for rutting in the asphalts. All three viscoelastic functions were shown to be interchangeable within the linear viscoelastic region. When subjected to large deformation in the direct tension test, asphalt binders behaved nonlinear viscoelastic in which the data under bending, shear and tension modes were not comparable. The asphalts were, however, found toe exhibit linear viscoelasticity up to the failure point in the steady-state strain region.

Chen, J.S.; Tsai, C.J. [National Cheng-Kung Univ., Tainan (Taiwan, Province of China). Dept. of Civil Engineering] [National Cheng-Kung Univ., Tainan (Taiwan, Province of China). Dept. of Civil Engineering

1998-12-01

49

Severity effects of dual-tandem and dual-tridem repeated heavier aircraft gear loading on pavement rutting performance  

Microsoft Academic Search

In this paper, the rutting behaviour of flexible test pavements subjected to multiple-wheel heavy aircraft gear loading at the National Airport Pavement Test Facility (NAPTF) are characterized. Two series of traffic tests were conducted. During the first series, a Boeing 777 (B777) aircraft gear and a Boeing 747 (B747) gear were trafficked on two low-strength subgrade and two medium-strength subgrade

Kasthurirangan Gopalakrishnan; Marshall R. Thompson

2006-01-01

50

Evaluation of various surface-sealing techniques for the preventative maintenance of flexible pavements. Research report(Final)  

SciTech Connect

The selection of an appropriate surface-seal technique for the preventative maintenance of flexible pavements has been a major concern among the various highway agencies for a number of years. In an effort to better equip the engineer in making decisions concerning the selection of the most cost-effective method of pavement maintenance, seven of the different surface-sealing techniques currently available in Florida were constructed in the fall of 1984 for evaluation. The only major problems encountered at the time of construction was the loss of cover material in the sand seal, mineral seal, and surface-treatment sections and raveling in the slurry seal section. These problems are believed to have been caused by traffic on the roadway before adequate curing had occurred. The test sections were evaluated immediately after construction and at 6 months, 1 year, 2 years, and 3 years, with the evaluation consisting of rut-depth measurements, crack survey, dynamic deflection measurements, rideability, and friction testing. At the conclusion of 3 years, the cost-effectiveness of each section was determined.

Musselman, J.A.; Leitner, E.B.; Murphy, K.H.; Page, G.C.

1989-02-01

51

A Methodology for Developing Performance-Related Specifications for Pavement Preservation Treatments  

E-print Network

, thin HMA Service Life Age or Traffic TR: Threshold for Major Rehab or Reconstruction TP: Threshold for Preservation P av em en t C on di tio n Service Life Age or Traffic P av em en t C on di tio n (a) Pavement Performance with Preservation (b...

Liu, Litao

2013-09-23

52

Development of Pavement Performance Models by Combining Experimental and Field Data  

Microsoft Academic Search

The objective of this paper is to demonstrate the development of pavement performance models by combining experimental and field data. A two step approach was used. In the first step a riding quality model based on serviceability consideration is developed. The data set of the American Association of State Highways Officials~AASHO! Road Test is used to this effect. Due to

J. A. Prozzi

2004-01-01

53

Hydraulic and treatment performance of pervious pavements under variable drying and wetting regimes.  

PubMed

Pervious pavements are an effective stormwater treatment technology. However, their performance under variable drying and wetting conditions have yet to be tested, particularly under a continuous time scale. This paper reports on the clogging behaviour and pollutant removal efficiency of three pervious pavement types over 26 accelerated years. These pavements were monolithic porous asphalt (PA), Permapave (PP) and modular Hydrapave (HP). Over a cycle of 13 days, the period of which was equivalent to the average annual Brisbane, Australia rainfall (1,200 mm), the pavements were randomly dosed with four different flows. Drying events of 3 h duration were simulated during each flow. Inflow and outflow samples were collected and analysed for Total Suspended Solids (TSS), Total Phosphorus (TP) and Total Nitrogen (TN). To evaluate the rate of clogging, a 1 in 5 year Brisbane storm event was simulated in the 6th, 8th, 12th, 16th, 20th and 24th week. Under normal dosing conditions, none of the pavements showed signs of clogging even after 15 years. However, under storm conditions, both PA and HP started to clog after 12 years, while PP showed no signs of clogging after 26 years. The drying and various flow events showed no effects in TSS removal, with all systems achieving a removal of approximately 100%. The average TP removal was 20% for all flows except for low flow, which had a significant amount of leaching over time. Leaching from TN was also observed during all flows except high flow. The TSS, TP and TN results observed during storm events were similar to that of high flow. PMID:22335113

Yong, C F; Deletic, A; Fletcher, T D; Grace, M R

2011-01-01

54

Anisotropic Characterization and Performance Prediction of Chemically and Hydraulically Bounded Pavement Foundations  

E-print Network

ANISOTROPIC CHARACTERIZATION AND PERFORMANCE PREDICTION OF CHEMICALLY AND HYDRAULICALLY BOUNDED PAVEMENT FOUNDATIONS A Dissertation by REZA SALEHI ASHTIANI Submitted to the Office of Graduate Studies of Texas A&M University... FOUNDATIONS A Dissertation by REZA SALEHI ASHTIANI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Chair of Committee...

Salehi Ashtiani, Reza

2010-10-12

55

Thermal stresses of flexible pavement with consideration of temperature-dependent material characteristics using stiffness matrix method  

NASA Astrophysics Data System (ADS)

The asphalt pavement is regarded as a multilayered elastic half space axisymmetrical body. By introducing the relationship between material characteristics and temperature into the fundamental equations of thermoelasticity and using mathematic methods of Laplace and Hankel integral transformation, the stiffness matrix for a layer is derived firstly. Then the global stiffness matrix is established for multilayered elastic half space using the finite element concepts in which layers are completely contacted. Therefore, explicit solution for thermal stresses of the asphalt pavement is obtained from the solution of the algebra equation formed by global stiffness matrix and the inverse Hankel and Laplace integral transformation. Because the elements of matrix do not include positive exponential function, the calculation is not overflowed and the shortages of transfer matrix method are overcome. This approach serves as a better model for real pavement structure as it takes into account the relationships between the material characteristics and temperature in the pavement system.

Geng, Litao; Ren, Ruibo; Zhong, Yang; Xu, Qian

2011-02-01

56

A study of certain elastic and plastic strains induced in flexible pavement systems by repetitive wheel loads  

E-print Network

of Selected Test Sites VI. EVALUATION GF EQUIPMENT AHD TESTING PROCEDURES The Bankelman Beam 37 Individual Pavement Deformation Measurement Capability Effect of extrusion Minor errors Suitability for Measuring Repetitive Deflections 41 47 The Test... deflection test results 51 TABLE OF CONTENTS (CONTINUED) CHAPTER PAGE Recovery of Deformed Pavement The Overall Validity of the Data Obtained VII. CORRECTION OF IHE FIELD DATA 58 61 63 The Indicated Error The Correction Process 63 67 VIII...

Meyer, Kirby Thomas

1959-01-01

57

Stochastic Modeling of Future Highway Maintenance Costs for Flexible Type Highway Pavement Construction Projects  

E-print Network

increased needs to rebuild deteriorated transportation networks. For major highway maintenance projects, a federal rule enforces to perform a life-cycle cost analysis (LCCA). The lack of analytical methods for LCCA creates many challenges of STAs to comply...

Kim, Yoo Hyun

2012-07-16

58

Water quality and quantity assessment of pervious pavements performance in experimental car park areas.  

PubMed

Pervious pavements have become one of the most used sustainable urban drainage system (SUDS) techniques in car parks. This research paper presents the results of monitoring water quality from several experimental car park areas designed and constructed in Spain with bays made of interlocking concrete block pavement, porous asphalt, polymer-modified porous concrete and reinforced grass with plastic and concrete cells. Moreover, two different sub-base materials were used (limestone aggregates and basic oxygen furnace slag). This study therefore encompasses the majority of the materials used as permeable surfaces and sub-base layers all over the world. Effluent from the test bays was monitored for dissolved oxygen, pH, electric conductivity, total suspended solids, turbidity and total petroleum hydrocarbons in order to analyze the behaviour shown by each combination of surface and sub-base materials. In addition, permeability tests were undertaken in all car parks using the 'Laboratorio Caminos Santander' permeameter and the Cantabrian Portable Infiltrometer. All results are presented together with the influence of surface and sub-base materials on water quality indicators using bivariate correlation statistical analysis at a confidence level of 95%. The polymer-modified porous concrete surface course in combination with limestone aggregate sub-base presented the best performance. PMID:24718346

Sañudo-Fontaneda, Luis A; Charlesworth, Susanne M; Castro-Fresno, Daniel; Andres-Valeri, Valerio C A; Rodriguez-Hernandez, Jorge

2014-01-01

59

Long-term stormwater quantity and quality performance of permeable pavement systems.  

PubMed

This study examined the long-term effectiveness of permeable pavement as an alternative to traditional impervious asphalt pavement in a parking area. Four commercially available permeable pavement systems were evaluated after 6 years of daily parking usage for structural durability, ability to infiltrate precipitation, and impacts on infiltrate water quality. All four permeable pavement systems showed no major signs of wear. Virtually all rainwater infiltrated through the permeable pavements, with almost no surface runoff. The infiltrated water had significantly lower levels of copper and zinc than the direct surface runoff from the asphalt area. Motor oil was detected in 89% of samples from the asphalt runoff but not in any water sample infiltrated through the permeable pavement. Neither lead nor diesel fuel were detected in any sample. Infiltrate measured 5 years earlier displayed significantly higher concentrations of zinc and significantly lower concentrations of copper and lead. PMID:14511707

Brattebo, Benjamin O; Booth, Derek B

2003-11-01

60

Performance of pervious pavement parking bays storing rainwater in the north of Spain.  

PubMed

Pervious pavements are drainage techniques that improve urban water management in a sustainable manner. An experimental pervious pavement parking area has been constructed in the north of Spain (Santander), with the aim of harvesting good quality rainwater. Forty-five pervious pavement structures have been designed and constructed to measure stored water quantity and quality simultaneously. Ten of these structures are specifically constructed with different geotextile layers for improving water storage within the pavements. Following the confirmation in previous laboratory experiments that the geotextile influenced on water storage, two different geosynthetics (Inbitex and a One Way evaporation control membrane) and control pervious pavements with no geotextile layers were tested in the field. Weather conditions were monitored in order to find correlations with the water storage within the pervious pavement models tested. During one year of monitoring the three different pervious pavement types tested remained at their maximum storage capacity. The heavy rain events which occurred during the experimental period caused evaporation rates within the pervious pavements to be not significant, but allowed the researchers to observe certain trends in the water storage. Temperature was the most closely correlated weather factor with the level of the water stored within the pervious pavements tested. PMID:20706008

Gomez-Ullate, E; Bayon, J R; Coupe, S; Castro-Fresno, D

2010-01-01

61

Binzhou Perpetual Pavement Test Road  

Microsoft Academic Search

Expressway construction has been carried out on a large-scale in China. Vigorous economical development has caused rapid growth in traffic volume and truck axle loads creating a severe challenge for the pavement structure design. Therefore, the high-performance and low- maintenance cost of a long-life perpetual pavement structure is gaining attention. This paper discusses the first perpetual asphalt pavement test road

Yongshun Yang; Jincheng Wei; Wang Lin; David Timm; Gerald Huber

2009-01-01

62

Hydrologic and Pollutant Removal Performance of a Full-Scale, Fully Functional Permeable Pavement Parking Lot  

EPA Science Inventory

In accordance with the need for full-scale, replicated studies of permeable pavement systems used in their intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage conditions, and maintenance regimes to evaluate these systems, the EPA?s Urb...

63

Permeable Pavement  

NSDL National Science Digital Library

Students investigate how different riparian ground covers, such as grass or pavement, affect river flooding. They learn about permeable and impermeable materials through the measurement how much water is absorbed by several different household materials in a model river. Students use what they learn to make recommendations for engineers developing permeable pavement. Also, they consider several different limitations for design in the context of a small community.

Integrated Teaching And Learning Program

64

Performance Based Mechanistic-Empirical Approach to Assess Joint Sealant Effectiveness on Sustainability of Concrete Pavement Infrastructure  

E-print Network

The primary purpose of sealing joints in rigid pavement is to prevent or reduce the amount of water infiltrating into pavement structure. It is well accepted that the presence of moisture in a pavement structure is a contributor to a variety...

Neshvadian Bakhsh, Keivan

2014-08-11

65

[ ]April 2013 Thickness is currently a pay item for portland cement concrete (PCC) pavements  

E-print Network

) pavements and a quality control item for both PCC and hot mix asphalt (HMA) pavements. A change in pavement are performed by destructively coring the finished pavement and measuring the thickness of the core are collected for each lot. Today, multiple non- destructive pavement evaluation tools are available

Harms, Kyle E.

66

High-Performance Flexible Waveguiding Photovoltaics  

PubMed Central

The use of flat-plane solar concentrators is an effective approach toward collecting sunlight economically and without sun trackers. The optical concentrators are, however, usually made of rigid glass or plastics having limited flexibility, potentially restricting their applicability. In this communication, we describe flexible waveguiding photovoltaics (FWPVs) that exhibit high optical efficiencies and great mechanical flexibility. We constructed these FWPVs by integrating poly-Si solar cells, a soft polydimethylsiloxane (PDMS) waveguide, and a TiO2-doped backside reflector. Optical microstructures that increase the light harvesting ability of the FWPVs can be fabricated readily, through soft lithography, on the top surface of the PDMS waveguide. Our optimized structure displayed an optical efficiency of greater than 42% and a certified power conversion efficiency (PCE) of 5.57%, with a projected PCE as high as approximately 18%. This approach might open new avenues for the harvesting of solar energy at low cost with efficient, mechanically flexible photovoltaics. PMID:23873225

Chou, Chun-Hsien; Chuang, Jui-Kang; Chen, Fang-Chung

2013-01-01

67

High-performance flexible waveguiding photovoltaics.  

PubMed

The use of flat-plane solar concentrators is an effective approach toward collecting sunlight economically and without sun trackers. The optical concentrators are, however, usually made of rigid glass or plastics having limited flexibility, potentially restricting their applicability. In this communication, we describe flexible waveguiding photovoltaics (FWPVs) that exhibit high optical efficiencies and great mechanical flexibility. We constructed these FWPVs by integrating poly-Si solar cells, a soft polydimethylsiloxane (PDMS) waveguide, and a TiO?-doped backside reflector. Optical microstructures that increase the light harvesting ability of the FWPVs can be fabricated readily, through soft lithography, on the top surface of the PDMS waveguide. Our optimized structure displayed an optical efficiency of greater than 42% and a certified power conversion efficiency (PCE) of 5.57%, with a projected PCE as high as approximately 18%. This approach might open new avenues for the harvesting of solar energy at low cost with efficient, mechanically flexible photovoltaics. PMID:23873225

Chou, Chun-Hsien; Chuang, Jui-Kang; Chen, Fang-Chung

2013-01-01

68

High-Performance Flexible Waveguiding Photovoltaics  

NASA Astrophysics Data System (ADS)

The use of flat-plane solar concentrators is an effective approach toward collecting sunlight economically and without sun trackers. The optical concentrators are, however, usually made of rigid glass or plastics having limited flexibility, potentially restricting their applicability. In this communication, we describe flexible waveguiding photovoltaics (FWPVs) that exhibit high optical efficiencies and great mechanical flexibility. We constructed these FWPVs by integrating poly-Si solar cells, a soft polydimethylsiloxane (PDMS) waveguide, and a TiO2-doped backside reflector. Optical microstructures that increase the light harvesting ability of the FWPVs can be fabricated readily, through soft lithography, on the top surface of the PDMS waveguide. Our optimized structure displayed an optical efficiency of greater than 42% and a certified power conversion efficiency (PCE) of 5.57%, with a projected PCE as high as approximately 18%. This approach might open new avenues for the harvesting of solar energy at low cost with efficient, mechanically flexible photovoltaics.

Chou, Chun-Hsien; Chuang, Jui-Kang; Chen, Fang-Chung

2013-07-01

69

LRRB Pavement Management Systems Pavement Management Systems  

E-print Network

LRRB Pavement Management Systems Pavement Management Systems Presented by: Michael Marti SRF for implementing and monitoring research results (RIC) #12;LRRB Pavement Management Systems LRRB Structure LRRB and counties in implementing Pavement Management and/or using better §Project produced several deliverables

Minnesota, University of

70

Development of Pavement Temperature Contours for India  

NASA Astrophysics Data System (ADS)

The stress-strain response of the bituminous pavements is highly sensitive to temperature. To systematically analyze the pavement performance, it is necessary that one understands the variation of pavement temperature spatially and temporally during the life time of a pavement. In this investigation, historic air temperature data for 37 locations across India was collected. Using this database, pavement temperature data was predicted by an appropriate air temperature-pavement temperature model. High and low temperature pavement temperature contours were generated for the first time for India. It was seen that the locations spanning from Srinagar to Madhya Pradesh and Rajasthan to Orissa were extremely critical. The minimum temperature in these locations was 10 C and the maximum temperature was around 68 C. Clearly such information is necessary when making choice of binder grade and bituminous layer thickness.

Nivitha, M. R.; Krishnan, J. M.

2014-06-01

71

Effects of Using Silica Fume and Polycarboxylate-Type Superplasticizer on Physical Properties of Cementitious Grout Mixtures for Semiflexible Pavement Surfacing  

PubMed Central

Semi-flexible pavement surfacing is a composite pavement that utilizes the porous pavement structure of the flexible bituminous pavement, which is subsequently grouted with appropriate cementitious materials. This study aims to investigate the compressive strength, flexural strength, and workability performance of cementitious grout. The grout mixtures are designed to achieve high strength and maintain flow properties in order to allow the cement slurries to infiltrate easily through unfilled compacted skeletons. A paired-sample t-test was carried out to find out whether water/cement ratio, SP percentages, and use of silica fume influence the cementitious grout performance. The findings showed that the replacement of 5% silica fume with an adequate amount of superplasticizer and water/cement ratio was beneficial in improving the properties of the cementitious grout. PMID:24526911

Karim, Mohamed Rehan; Mahmud, Hilmi; Mashaan, Nuha S.; Katman, Herdayati; Husain, Nadiah Md

2014-01-01

72

Artificial intelligence modeling to evaluate field performance of photocatalytic asphalt pavement for ambient air purification.  

PubMed

In recent years, the application of titanium dioxide (TiO?) as a photocatalyst in asphalt pavement has received considerable attention for purifying ambient air from traffic-emitted pollutants via photocatalytic processes. In order to control the increasing deterioration of ambient air quality, urgent and proper risk assessment tools are deemed necessary. However, in practice, monitoring all process parameters for various operating conditions is difficult due to the complex and non-linear nature of air pollution-based problems. Therefore, the development of models to predict air pollutant concentrations is very useful because it can provide early warnings to the population and also reduce the number of measuring sites. This study used artificial neural network (ANN) and neuro-fuzzy (NF) models to predict NOx concentration in the air as a function of traffic count (Tr) and climatic conditions including humidity (H), temperature (T), solar radiation (S), and wind speed (W) before and after the application of TiO? on the pavement surface. These models are useful for modeling because of their ability to be trained using historical data and because of their capability for modeling highly non-linear relationships. To build these models, data were collected from a field study where an aqueous nano TiO? solution was sprayed on a 0.2-mile of asphalt pavement in Baton Rouge, LA. Results of this study showed that the NF model provided a better fitting to NOx measurements than the ANN model in the training, validation, and test steps. Results of a parametric study indicated that traffic level, relative humidity, and solar radiation had the most influence on photocatalytic efficiency. PMID:24699867

Asadi, Somayeh; Hassan, Marwa; Nadiri, Ataallah; Dylla, Heather

2014-07-01

73

Exploration of Pavement Oxidation Model Applications and Field Validation  

E-print Network

Asphalt paved road is one of the building blocks of the modem world. Flexibility is one of its major advantages; however, this flexibility suffers from asphalt oxidation since the first day of pavement service life. Several elements of binder...

Cui, Yuanchen

2014-08-11

74

Quantity Flexibility Contracts and Supply Chain Performance  

Microsoft Academic Search

The Quantity Flexibility (QF) contract is a method for coordinating materials and information flows in supply chains operating under rolling-horizon planning. It stipulates a maximum percentage revision each element of the period-by-period replenishment schedule is allowed per planning iteration. The supplier is obligated to cover any requests that remain within the upside limits. The bounds on reductions are a form

A. A. Tsay; W. S. Lovejoy

1999-01-01

75

Influence of hinge point on flexible flap aerodynamic performance  

NASA Astrophysics Data System (ADS)

Large scale wind turbines lead to increasing blade lengths and weights, which presents new challenges for blade design. This paper selects NREL S809 airfoil, uses the parameterized technology to realize the flexible trailing edge deformation, researches the static aerodynamic characteristics of wind turbine blade airfoil with flexible deformation, and the dynamic aerodynamic characteristics in the process of continuous deformation, analyses the influence of hinge point position on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With hinge point moving forward, total aerodynamic performance of flexible flap improves. Positive swing angle can push the transition point backward, thus postpones the occurrence of the transition phenomenon.

Y Zhao, H.; Ye, Z.; Wu, P.; Li, C.

2013-12-01

76

Flexible nanoscale high-performance FinFETs.  

PubMed

With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics. PMID:25185112

Torres Sevilla, Galo A; Ghoneim, Mohamed T; Fahad, Hossain; Rojas, Jhonathan P; Hussain, Aftab M; Hussain, Muhammad Mustafa

2014-10-28

77

In-depth study of cold in-place recycled-pavement performance. Volume 1. Final report. Rept. for Dec 88-Oct 90  

SciTech Connect

Oregon has developed a mix design procedure for cold in-place recycled (CIR) asphalt concrete pavements. The procedure involves estimation of an initial emulsion content based on gradation of recycled asphalt pavement (RAP), asphalt content of RAP, and penetration and viscosity of recovered asphalt. When an estimated emulsion content is determined, Marshall-sized specimens are prepared for a range of emulsion contents with the range centered on the estimated emulsion content. Hveem and Marshall stability, resilient modulus, and index of retained modulus (IRM) tests are performed on the specimens and a design emulsion content is selected based upon these results. Because of variations in RAP properties, continual need for field adjustments, and the difficulty of interpreting mix property test results, only the estimation part of the procedure is currently implemented. The paper describes the mix design procedure and presents lab results demonstrating the difficulty of choosing emulsion content based on Hveem and Marshall stability, resilient modulus and IRM. Data comparing design emulsion content with actual emulsion contents used in the field are presented. Selection of water content is discussed. Test results of mix properties monitored over time are presented, demonstrating the curing of the emulsion. Performance data for CIR pavements constructed from 1984 through 1988 are presented as well as initial results of an attempt to use lime during recycling to correct a stripped pavement. A construction and inspection manual is presented as a separate document.

Scholz, T.V.; Hicks, R.G.; Rogge, D.F.

1990-12-01

78

Compaction of asphalt pavement. Final report  

SciTech Connect

This synthesis will be of interest to construction and materials engineers, paving contractors, equipment manufacturers, and others who are involved in assessing the performance of asphalt pavements. Information is presented on various issues related to compaction of asphalt pavements. Compaction is one of the most important factors affecting the performance of asphalt pavements. The report of the Transportation Research Board describes the theory, methods, equipment, and specifications related to the compaction of asphalt pavements. A brief history of, the importance of, and factors affecting compaction are also discussed. Construction influences, density measurements, and trends are also considered.

Hughes, C.S.

1989-10-01

79

THE USE OF EAF STEEL SLAG IN BITUMINOUS MIXES FOR FLEXIBLE PAVEMENTS: A NUMERICAL AND EXPERIMENTAL ANALYSIS  

Microsoft Academic Search

The use of the metallurgical slags in substitution of the natural aggregates, is a consolidated reality in the field of the road constructions, by now from several years. Numerous international studies can document the positive performances of the mixtures realized with such marginal material, in particular for what concerns the Blastfurnace slag (BF) and the Basic Oxygen Steel slag (BOS),

80

The new Mechanistic-Empirical Pavement Design Guide (MEPDG) developed under the National Cooperative Highway Research Program (NCHRP) Project 1-37A represents a major change as compared to the 1993 AASHTO Pavement  

E-print Network

The new Mechanistic-Empirical Pavement Design Guide (MEPDG) developed under the National AASHTO Pavement Design Guide. MEPDG provides a rational pavement design framework based on the pavement performance. Before replacing the 1993 Pavement Design Guide (and its accompanying DARWin 3

Harms, Kyle E.

81

PARTIAL-DEPTH REPAIR OF CONCRETE PAVEMENTSCONCRETE PAVEMENTS  

E-print Network

April 2012 PARTIAL-DEPTH REPAIR OF CONCRETE PAVEMENTSCONCRETE PAVEMENTS GUIDE FOR #12;#12;Guide for Partial-Depth Repair of Concrete Pavements i Technical Report Documentation Page 1. Report No. 2 Depth Repair of Concrete Pavements April 2012 6. Performing Organization Code 7. Author(s) 8. Performing

82

Stretch shorten cycle performance enhancement through flexibility training.  

PubMed

Sixteen experienced male powerlifters served as subjects in a training study designed to examine the effect of flexibility training on: (i) the stiffness of the series elastic components (SEC) of the upper body musculature and (ii) rebound and purely concentric bench press performance. Nine of the subjects participated in two sessions of flexibility training twice per week for 8 wk. Prior to and after the training period the subjects' static flexibility, SEC stiffness, rebound bench press (RBP), and purely concentric bench press (PCBP) performance were recorded. The flexibility training induced a significant reduction in the maximal stiffness of the SEC. Furthermore, the experimental subjects produced significantly more work during the initial concentric portion of the RBP lift, enabling a significantly greater load to be lifted in the post-training testing occasion. The benefits to performance achieved by the experimental group consequent to flexibility training were greater during the RBP lift as compared with the PCBP lift. The control subjects exhibited no change in any variable over the training period. These results implied that the RBP performance enhancement observed consequent to flexibility training was directly caused by a reduction in SEC stiffness, increasing the utilization of elastic strain energy during the RBP lift. PMID:1548985

Wilson, G J; Elliott, B C; Wood, G A

1992-01-01

83

High-performance magnetic sensorics for printable and flexible electronics.  

PubMed

High-performance giant magnetoresistive (GMR) sensorics are realized, which are printed at predefined locations on flexible circuitry. Remarkably, the printed magnetosensors remain fully operational over the complete consumer temperature range and reveal a giant magnetoresistance up to 37% and a sensitivity of 0.93 T(-1) at 130 mT. With these specifications, printed magnetoelectronics can be controlled using flexible active electronics for the realization of smart packaging and energy-efficient switches. PMID:25366983

Karnaushenko, Daniil; Makarov, Denys; Stöber, Max; Karnaushenko, Dmitriy D; Baunack, Stefan; Schmidt, Oliver G

2015-02-01

84

CONCRETE PAVEMENT Reference Manual  

E-print Network

CONCRETE PAVEMENT Reference Manual Prepared for Federal Highway Administration Office of Pavement by National Concrete Pavement Technology Center at Iowa State University 2711 South Loop Drive, Suite 4700 No. 3. Recipient's Catalog No. 4. Title and Subtitle 5. Report Date February 2008 Concrete Pavement

85

Flexibility.  

ERIC Educational Resources Information Center

Flexibility is an important aspect of all sports and recreational activities. Flexibility can be developed and maintained by stretching exercises. Exercises designed to develop flexibility in ankle joints, knees, hips, and the lower back are presented. (JN)

Humphrey, L. Dennis

1981-01-01

86

High-performance, flexible, deployable array development for space applications  

NASA Astrophysics Data System (ADS)

Flexible, deployable arrays are an attractive alternative to conventional solar arrays for near-term and future space power applications, particularly due to their potential for high specific power and low storage volume. Combined with low-cost flexible thin-film photovoltaics, these arrays have the potential to become an enabling or an enhancing technology for many missions. In order to expedite the acceptance of thin-film photovoltaics for space applications, however, parallel development of flexible photovoltaics and the corresponding deployable structure is essential. Many innovative technologies must be incorporated in these arrays to ensure a significant performance increase over conventional technologies. For example, innovative mechanisms which employ shape memory alloys for storage latches, deployment mechanisms, and array positioning gimbals can be incorporated into flexible array design with significant improvement in the areas of cost, weight, and reliability. This paper discusses recent activities at Martin Marietta regarding the development of flexible, deployable solar array technology. Particular emphasis is placed on the novel use of shape memory alloys for lightweight deployment elements to improve the overall specific power of the array. Array performance projections with flexible thin-film copper-indium-diselenide (CIS) are presented, and government-sponsored solar array programs recently initiated at Martin Marietta through NASA and Air Force Phillips Laboratory are discussed.

Gehling, Russell N.; Armstrong, Joseph H.; Misra, Mohan S.

1994-09-01

87

SOURCE: UNIVERSITY OF CALIFORNIA PAVEMENT RESEARCH CENTER PAVEMENT TECHNOLOGY UPDATE  

E-print Network

SOURCE: UNIVERSITY OF CALIFORNIA PAVEMENT RESEARCH CENTER PAVEMENT TECHNOLOGY UPDATE at the California Department of Transportation. Content is provided by the University of California Pavement Research Center. The University of California Pavement Research Center Using innovative research and sound

California at Berkeley, University of

88

COMPOSITE PORTLAND CEMENT CONCRETE PAVEMENTS (Tollway) Effective: January 30, 2012  

E-print Network

COMPOSITE PORTLAND CEMENT CONCRETE PAVEMENTS (Tollway) Effective: January 30, 2012 Revised: May 8 for special applications to composite pavements as shown and described on the Drawings and in this Special(s) that meets the performance requirements for the intended pavement; 4. Constructing a trial section

89

MANUAL FOR WEB-BASED TXDOT RIGID PAVEMENT Sureel Saraf  

E-print Network

0-5445-P2 MANUAL FOR WEB-BASED TXDOT RIGID PAVEMENT DATABASE Authors: Sureel Saraf Moon Won TxDOT Project 0-5445: Project Level Performance Database for Rigid Pavements in Texas SEPTEMBER 2007, REV. JULY-Based Information System for Rigid Pavements User's Manual Texas Department of Transportation July 9, 2009 #12

Texas at Austin, University of

90

OVERLAYSSustainable Solutions for Resurfacing and Rehabilitating Existing Pavements THIRD EDITION  

E-print Network

Pavements May 2014 THIRD EDITION ACPA publicationTB021.03P #12;On the Cover source:Todd Hanson, Iowa DOT and Rehabilitating Existing Pavements (3rd edition) May 2014 6. Performing Organization Code 7. Author(s) 8 10. Work Unit No. (TRAIS) National Concrete Pavement Technology Center Institute for Transportation

91

QUANTIFYING THE BENEFITS FOR USING GEOSYNTHETICS IN UNBOUND BASE COURSE OF PAVEMENTS IN HIGH PI CLAYS  

E-print Network

QUANTIFYING THE BENEFITS FOR USING GEOSYNTHETICS IN UNBOUND BASE COURSE OF PAVEMENTS IN HIGH PI CLAYS By: Ranjiv Gupta1 and J. G. Zornberg, Advisor2 ABSTRACT Flexible pavements over high plasticity methodology to do the same. The present study aims at constructing field test sections on actual pavements

Zornberg, Jorge G.

92

Flexibility of movement organization in piano performance  

PubMed Central

Piano performance involves a large repertoire of highly skilled movements. The acquisition of these exceptional skills despite innate neural and biomechanical constraints requires a sophisticated interaction between plasticity of the neural system and organization of a redundant number of degrees of freedom (DOF) in the motor system. Neuroplasticity subserving virtuosity of pianists has been documented in neuroimaging studies investigating effects of long-term piano training on structure and function of the cortical and subcortical regions. By contrast, recent behavioral studies have advanced the understanding of neuromuscular strategies and biomechanical principles behind the movement organization that enables skilled piano performance. Here we review the motor control and biomechanics literature, introducing the importance of describing motor behaviors not only for understanding mechanisms responsible for skillful motor actions in piano playing, but also for advancing diagnosis and rehabilitation of movement disorders caused by extensive piano practice. PMID:23882199

Furuya, Shinichi; Altenmüller, Eckart

2013-01-01

93

Flexibility of movement organization in piano performance.  

PubMed

Piano performance involves a large repertoire of highly skilled movements. The acquisition of these exceptional skills despite innate neural and biomechanical constraints requires a sophisticated interaction between plasticity of the neural system and organization of a redundant number of degrees of freedom (DOF) in the motor system. Neuroplasticity subserving virtuosity of pianists has been documented in neuroimaging studies investigating effects of long-term piano training on structure and function of the cortical and subcortical regions. By contrast, recent behavioral studies have advanced the understanding of neuromuscular strategies and biomechanical principles behind the movement organization that enables skilled piano performance. Here we review the motor control and biomechanics literature, introducing the importance of describing motor behaviors not only for understanding mechanisms responsible for skillful motor actions in piano playing, but also for advancing diagnosis and rehabilitation of movement disorders caused by extensive piano practice. PMID:23882199

Furuya, Shinichi; Altenmüller, Eckart

2013-01-01

94

Lower bound shakedown analysis of layered pavements using discontinuous stress fields  

Microsoft Academic Search

Pavements and railways are subjected to repeated wheel loads of different magnitudes. Both load magnitudes and number of repetitions of load need to be considered in order to avoid significant damages to a pavement. A conventional finite element technique is convenient for calculating static pavement responses, but the prediction of pavement performance under repeated loading is much more difficult as

H. S. Yu; M. Z. Hossain

1998-01-01

95

Effects of structure flexibility on horizontal axis wind turbine performances  

NASA Astrophysics Data System (ADS)

This work illustrates the effects of flexibility of rotor blades and turbine tower on the performances of an horizontal axis wind turbine (HAWT) designed by our ADAG research group, by means of several example applied on a recent project for a active pitch controlled upwind 60 kW HAWT. The influence of structural flexibility for blade only, tower only and blade coupled with tower configuration is investigated using an aero-elastic computer-aided engineering (CAE) tool for horizontal axis wind turbines named FAST developed at National Renewable Energy Laboratory (NREL) of USA. For unsteady inflow conditions in front of the isolated HAWT the performances in rigid and flexible operation mode are computed and compared in order to illustrate the limitation included within a classical rigid body approach to wind turbine simulation.

Coiro, D. P.; Daniele, E.; Scherillo, F.

2013-10-01

96

A Study on the Estimation of the Performance of Sediment Pavement and the Required Function of the Farm Road in a Paddy Area  

NASA Astrophysics Data System (ADS)

The pavement rate of the farm road which becomes important in activities of agricultural production, circulation of agricultural products and rural life is low. There are many farm roads to which the function of traveling performance, traveling comfort and prevention of the damage of agricultural products in transportation is not secured. Maintenance including improvement in the pavement rate of a farm road must be economically carried out based on the service environment, the circumference environment and the required function according to the kind of farm road. In this research, the problem of the farm road in a paddy area was extracted from the questionnaire to a land improvement district as an administrator, and the conditions which should be taken into consideration in maintenance of a farm road were clarified. The problem of a farm road is deformation of a road surface and a request is a period which does not need to repair. Moreover, the present performance of ground property and road surface of sediment pavement on-farm road was evaluated. Positive correlation is between the standard deviation of modulus of elasticity of the soil and surface roughness, negative correlation is between the modulus of elasticity of the soil in the rut and rutting depth.

Ogata, Hidehiko; Noda, Tomoyuki; Sakamoto, Yasufumi; Shinotsuka, Masanori; Kamada, Osamu; Nakamura, Kazuaki

97

Overall Thermal Performance of Flexible Piping Under Simulated Bending Conditions  

NASA Technical Reports Server (NTRS)

Flexible, vacuum-insulated transfer lines for low-temperature applications have higher thermal losses than comparable rigid lines. Typical flexible piping construction uses corrugated tubes, inner and outer, with a multilayer insulation (MLI) system in the annular space. Experiments on vacuum insulation systems in a flexible geometry were conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. The effects of bending were simulated by causing the inner tube to be eccentric with the outer tube. The effects of spacers were simulated in a controlled way by inserting spacer tubes for the length of the cylindrical test articles. Two material systems, standard MLI and a layered composite insulation (LCI), were tested under the full range of vacuum levels using a liquid nitrogen boiloff calorimeter to determine the apparent thermal conductivity (k-value). The results indicate that the flexible piping under simulated bending conditions significantly degrades the thermal performance of the insulation system. These data are compared to standard MLI for both straight and flexible piping configurations. The definition of an overall k-value for actual field installations (k(sub oafi)) is described for use in design and analysis of cryogenic piping systems.

Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)

2001-01-01

98

Influence of inflow angle on flexible flap aerodynamic performance  

NASA Astrophysics Data System (ADS)

Large scale wind turbines have larger blade lengths and weights, which creates new challenges for blade design. This paper selects NREL S809 airfoil, and uses the parameterized technology to realize the flexible trailing edge deformation, researches the dynamic aerodynamic characteristics in the process of continuous flexible deformation, analyses the influence of inflow angle on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With inflow angle increases, dynamic lift-drag coefficient hysteresis loop shape deviation occurs, even turns into different shapes. Appropriate swing angle can improve the flap lift coefficient, but may cause early separation of flow. To improve the overall performance of wind turbine blades, different angular control should be used at different cross sections, in order to achieve the best performance.

Y Zhao, H.; Ye, Z.; Li, Z. M.; Li, C.

2013-12-01

99

Utilize Cementitious High Carbon Fly Ash (CHCFA) to Stabilize Cold In-Place Recycled (CIR) Asphalt Pavement as Base Coarse  

SciTech Connect

The purpose of this study was to evaluate the performance of cementitious high carbon fly ash (CHCFA) stabilized recycled asphalt pavement as a base course material in a real world setting. Three test road cells were built at MnROAD facility in Minnesota. These cells have the same asphalt surface layers, subbases, and subgrades, but three different base courses: conventional crushed aggregates, untreated recycled pavement materials (RPM), and CHCFA stabilized RPM materials. During and after the construction of the three cells, laboratory and field tests were carried out to characterize the material properties. The test results were used in the mechanistic-empirical pavement design guide (MEPDG) to predict the pavement performance. Based on the performance prediction, the life cycle analyses of cost, energy consumption, and greenhouse gasses were performed. The leaching impacts of these three types of base materials were compared. The laboratory and field tests showed that fly ash stabilized RPM had higher modulus than crushed aggregate and RPM did. Based on the MEPDG performance prediction, the service life of the Cell 79 containing fly ash stabilized RPM, is 23.5 years, which is about twice the service life (11 years) of the Cell 77 with RPM base, and about three times the service life (7.5 years) of the Cell 78 with crushed aggregate base. The life cycle analysis indicated that the usage of the fly ash stabilized RPM as the base of the flexible pavement can significantly reduce the life cycle cost, the energy consumption, the greenhouse gases emission. Concentrations of many trace elements, particularly those with relatively low water quality standards, diminish over time as water flows through the pavement profile. For many elements, concentrations below US water drinking water quality standards are attained at the bottom of the pavement profile within 2-4 pore volumes of flow.

Wen, Haifang; Li, Xiaojun; Edil, Tuncer; O'Donnell, Jonathan; Danda, Swapna

2011-02-05

100

STONE PAVEMENTS IN DESERTS  

Microsoft Academic Search

Stone pavements are armored surfaces comprising intricate mosaics of coarse particles, usually only one or two stones thick, set on or in fine material. They occur widely in many unvegetated areas, and preeminently in hot deserts. Pavement studies in several deserts, and especially in Chile and California, suggest that: 1) deflation may be a relatively unimportant process of pavement formation;

RONALD U. COOKE

1970-01-01

101

Rubber modified and performance based asphalt binder pavements: I-5 Nisqually River to Gravelly Lake. Post construction report  

SciTech Connect

The report describes the construction of asphalt pavements made with three types of asphalt binders. The three types of binders were PBA-6, PBA-6GR (ground rubber), and AR4000W. The two modified binders, PBA-6 and PBA-6GR, are being evaluated to determine their resistance to rutting as compared to the conventional binder, AR4000W.

Pierce, L.M.

1996-01-01

102

Hydrologic and Pollutant Removal Performance of a Full-Scale, Fully Functional Permeable Pavement Parking Lot - paper  

EPA Science Inventory

To meet the need for long-term, full-scale, replicated studies of permeable pavement systems used in their intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage conditions, and maintenance regimes to evaluate these systems, the EPA?s Urb...

103

Flexible high-performance carbon nanotube integrated circuits  

NASA Astrophysics Data System (ADS)

Carbon nanotube thin-film transistors are expected to enable the fabrication of high-performance, flexible and transparent devices using relatively simple techniques. However, as-grown nanotube networks usually contain both metallic and semiconducting nanotubes, which leads to a trade-off between charge-carrier mobility (which increases with greater metallic tube content) and on/off ratio (which decreases). Many approaches to separating metallic nanotubes from semiconducting nanotubes have been investigated, but most lead to contamination and shortening of the nanotubes, thus reducing performance. Here, we report the fabrication of high-performance thin-film transistors and integrated circuits on flexible and transparent substrates using floating-catalyst chemical vapour deposition followed by a simple gas-phase filtration and transfer process. The resulting nanotube network has a well-controlled density and a unique morphology, consisting of long (~10 µm) nanotubes connected by low-resistance Y-shaped junctions. The transistors simultaneously demonstrate a mobility of 35 cm2 V-1 s-1 and an on/off ratio of 6 × 106. We also demonstrate flexible integrated circuits, including a 21-stage ring oscillator and master-slave delay flip-flops that are capable of sequential logic. Our fabrication procedure should prove to be scalable, for example, by using high-throughput printing techniques.

Sun, Dong-Ming; Timmermans, Marina Y.; Tian, Ying; Nasibulin, Albert G.; Kauppinen, Esko I.; Kishimoto, Shigeru; Mizutani, Takashi; Ohno, Yutaka

2011-03-01

104

Flexible high-performance carbon nanotube integrated circuits.  

PubMed

Carbon nanotube thin-film transistors are expected to enable the fabrication of high-performance, flexible and transparent devices using relatively simple techniques. However, as-grown nanotube networks usually contain both metallic and semiconducting nanotubes, which leads to a trade-off between charge-carrier mobility (which increases with greater metallic tube content) and on/off ratio (which decreases). Many approaches to separating metallic nanotubes from semiconducting nanotubes have been investigated, but most lead to contamination and shortening of the nanotubes, thus reducing performance. Here, we report the fabrication of high-performance thin-film transistors and integrated circuits on flexible and transparent substrates using floating-catalyst chemical vapour deposition followed by a simple gas-phase filtration and transfer process. The resulting nanotube network has a well-controlled density and a unique morphology, consisting of long (~10 µm) nanotubes connected by low-resistance Y-shaped junctions. The transistors simultaneously demonstrate a mobility of 35 cm(2) V(-1) s(-1) and an on/off ratio of 6 × 10(6). We also demonstrate flexible integrated circuits, including a 21-stage ring oscillator and master-slave delay flip-flops that are capable of sequential logic. Our fabrication procedure should prove to be scalable, for example, by using high-throughput printing techniques. PMID:21297625

Sun, Dong-ming; Timmermans, Marina Y; Tian, Ying; Nasibulin, Albert G; Kauppinen, Esko I; Kishimoto, Shigeru; Mizutani, Takashi; Ohno, Yutaka

2011-03-01

105

4/28/2010 1Porous Pavements Porous Pavements  

E-print Network

4/28/2010 1Porous Pavements Porous Pavements for Stormwater Restoration in Urban Environments Cliff Aichinger Ramsey-Washington Metro Watershed District #12;4/28/2010 2Porous Pavements Porous Pavements Why am new volume reduction rules. Porous pavement is one of a relative few BMPs that address stormwater

Minnesota, University of

106

The development of correlations between HMA pavement performance and aggregate shape properties  

E-print Network

for mixes used in these projects was created. Statistical analysis was conducted to correlate HMA performance parameters to volumetric and aggregate shape characteristics. The results show the dominant effect that aggregate shape properties have on HMA...

McGahan, Jeremy

2006-04-12

107

A methodological framework for modeling pavement maintenance costs for projects with performance-based contracts  

Microsoft Academic Search

Performance-based maintenance contracts differ significantly from material and method-based contracts that have been traditionally used to maintain roads. Road agencies around the world have moved towards a performance-based contract approach because it offers several advantages like cost saving, better budgeting certainty, better customer satisfaction with better road services and conditions. Payments for the maintenance of road are explicitly linked to

Kamalesh Panthi

2009-01-01

108

A Methodological Framework for Modeling Pavement Maintenance Costs for Projects with Performance-based Contracts  

Microsoft Academic Search

Performance-based maintenance contracts differ significantly from material and method-based contracts that have been traditionally used to maintain roads. Road agencies around the world have moved towards a performance-based contract approach because it offers several advantages like cost saving, better budgeting certainty, better customer satisfaction with better road services and conditions. Payments for the maintenance of road are explicitly linked to

Kamalesh Panthi

2009-01-01

109

Mediaprocessors in medical imaging for high performance and flexibility  

NASA Astrophysics Data System (ADS)

New high performance programmable processors, called mediaprocessors, have been emerging since the early 1990s for various digital media applications, such as digital TV, set-top boxes, desktop video conferencing, and digital camcorders. Modern mediaprocessors, e.g., TI's TMS320C64x and Hitachi/Equator Technologies MAP-CA, can offer high performance utilizing both instruction-level and data-level parallelism. During this decade, with continued performance improvement and cost reduction, we believe that the mediaprocessors will become a preferred choice in designing imaging and video systems due to their flexibility in incorporating new algorithms and applications via programming and faster-time-to-market. In this paper, we will evaluate the suitability of these mediaprocessors in medical imaging. We will review the core routines of several medical imaging modalities, such as ultrasound and DR, and present how these routines can be mapped to mediaprocessors and their resultant performance. We will analyze the architecture of several leading mediaprocessors. By carefully mapping key imaging routines, such as 2D convolution, unsharp masking, and 2D FFT, to the mediaprocessor, we have been able to achieve comparable (if not better) performance to that of traditional hardwired approaches. Thus, we believe that future medical imaging systems will benefit greatly from these advanced mediaprocessors, offering significantly increased flexibility and adaptability, reducing the time-to-market, and improving the cost/performance ratio compared to the existing systems while meeting the high computing requirements.

Managuli, Ravi; Kim, Yongmin

2002-05-01

110

Flexible body dynamic stability for high performance aircraft  

NASA Technical Reports Server (NTRS)

Dynamic equations which include the effects of unsteady aerodynamic forces and a flexible body structure were developed for a free flying high performance fighter aircraft. The linear and angular deformations are assumed to be small in the body reference frame, allowing the equations to be linearized in the deformation variables. Equations for total body dynamics and flexible body dynamics are formulated using the hybrid coordinate method and integrated in a state space format. A detailed finite element model of a generic high performance fighter aircraft is used to generate the mass and stiffness matrices. Unsteady aerodynamics are represented by a rational function approximation of the doublet lattice matrices. The equations simplify for the case of constant angular rate of the body reference frame, allowing the effect of roll rate to be studied by computing the eigenvalues of the system. It is found that the rigid body modes of the aircraft are greatly affected by introducing a constant roll rate, while the effect on the flexible modes is minimal for this configuration.

Goforth, E. A.; Youssef, H. M.; Apelian, C. V.; Schroeder, S. C.

1991-01-01

111

Rutting Performance of Airport Hot-Mix Asphalt Characterized by Laboratory Performance Testing, Full-Scale Accelerated Pavement Testing, and Finite Element Modeling  

E-print Network

potential laboratory tests, (b) comparisons of laboratory tests results to full-scale accelerated pavement test results, and (c) analyses of results from finite element simulations. The laboratory study evaluated of the repeated load test, the static creep...

Rushing, John Ford

2014-04-25

112

Flow structure and performance of a flexible plunging airfoil  

NASA Astrophysics Data System (ADS)

An investigation was performed with the intent of characterizing the effect of flexibility on a plunging airfoil, over a parameter space applicable to birds and flapping MAVs. The kinematics of the motion was determined using of a high speed camera, and the deformations and strains involved in the motion were examined. The vortex dynamics associated with the plunging motion were mapped out using particle image velocimetry (PIV), and categorized according to the behavior of the leading edge vortex (LEV). The development and shedding process of the LEVs was also studied, along with their flow trajectories. Results of the flexible airfoils were compared to similar cases performed with a rigid airfoil, so as to determine the effects caused by flexibility. Aerodynamic loads of the airfoils were also measured using a force sensor, and the recorded thrust, lift and power coefficients were analyzed for dependencies, as was the overall propulsive efficiency. Thrust and power coefficients were found to scale with the Strouhal number defined by the trialing edge amplitude, causing the data of the flexible airfoils to collapse down to a single curve. The lift coefficient was likewise found to scale with trailing edge Strouhal number; however, its data tended to collapse down to a linear relationship. On the other hand, the wake classification and the propulsive efficiency were more successfully scaled by the reduced frequency of the motion. The circulation of the LEV was determined in each case and the resulting data was scaled using a parameter developed for this specific study, which provided significant collapse of the data throughout the entire parameter space tested.

Akkala, James Marcus

113

Performance-based design and analysis of flexible composite propulsors  

NASA Astrophysics Data System (ADS)

Advanced composite propellers, turbines, and jet engines have become increasingly popular in part because of their ability to provide improved performance over traditional metallic rotors through exploitation of the intrinsic bend-twist coupling characteristics of anisotropic composite materials. While these performance improvements can be significant from a conceptual perspective, the load-dependent deformation responses of adaptive blades make the design of these structures highly non-trivial. Hence, it is necessary to understand and predict the dependence of the deformations on the geometry, material constitution, and fluid-structure interaction responses across the entire range of expected loading conditions.The objective of this work is to develop a probabilistic performance-based design and analysis methodology for flexible composite propulsors. To demonstrate the method, it is applied for the design and analysis of two (rigid) metallic and (flexible) composite propellers for a twin-shafted naval combatant craft. The probabilistic operational space is developed by considering the variation of vessel thrust requirements as a function of the vessel speed and wave conditions along with the probabilistic speed profiles. The performance of the metallic and composite propellers are compared and discussed. The implications of load-dependent deformations of the flexible composite propeller on the operating conditions and the resulting performance with respect to propeller efficiency, power demand, and fluid cavitation are presented for both spatially uniform and varying flows. While the proposed framework is demonstrated for marine propellers, the methodology can be generally applied for any marine, aerospace, or wind energy structure that must operate in a wide range of loading conditions over its expected life.

Motley, Michael R.; Young, Yin L.

2011-11-01

114

12th Annual Minnesota Pavement  

E-print Network

12th Annual Minnesota Pavement Conference: Session Summaries Conference Sponsors: Minnesota Research Alliance (TERRA) Pavement Research Institute (PRI) Hosted by: Center for Transportation Studies provides information to practitioners and others in pavement design, construction, and maintenance

Minnesota, University of

115

The correlations between high performance work systems, human resource flexibility and organizational performance  

Microsoft Academic Search

The black box between High performance work systems(HPWS) and organizational performance is an important issue in the domain of Human Resource Management. Scholars strive hard to uncover it. After 2007's financial storm, they try to uncover it from the perspective of human resource flexibility which stems from the practices of HPWS and thereafter turns out to be organizational performance through

Xing Hui; Gao Su-ying; Zhang Yan-li; Zhang Jin

2010-01-01

116

Road Materials and Pavements Design. Volume X No X/2013, pages 1 to n Review of glass fiber grid use for pavement  

E-print Network

Road Materials and Pavements Design. Volume X No X/2013, pages 1 to n Review of glass fiber grid use for pavement reinforcement and APT experiments at IFSTTAR Mai Lan Nguyen* Juliette Blanc* Jean performance, to extend service life and thus to reduce maintenance costs of road pavements. Among a large

Paris-Sud XI, Université de

117

Semiconducor wires and ribbons for high performance flexible electronics.  

SciTech Connect

This article reviews the properties, fabrication and assembly of inorganic semiconductor materials that can be used as active building blocks to form high-performance transistors and circuits for flexible and bendable large-area electronics. Obtaining high performance on low temperature polymeric substrates represents a technical challenge for macroelectronics. Therefore, the fabrication of high quality inorganic materials in the form of wires, ribbons, membranes, sheets, and bars formed by bottom-up and top-down approaches, and the assembly strategies used to deposit these thin films onto plastic substrates will be emphasized. Substantial progress has been made in creating inorganic semiconducting materials that are stretchable and bendable, and the description of the mechanics of these form factors will be presented, including circuits in three-dimensional layouts. Finally, future directions and promising areas of research will be described.

Sun, Y.; Baca, A. J.; Ahn, J.-H.; Meitl, M.; Menard, E.; Kim, H.-S; Choi, W.; Kim, D.-H; Huang, Y.; Rogers, J. A.; Center for Nanoscale Materials; Univ. of Illinois

2008-01-01

118

Developing Flexible, High Performance Polymers with Self-Healing Capabilities  

NASA Technical Reports Server (NTRS)

Flexible, high performance polymers such as polyimides are often employed in aerospace applications. They typically find uses in areas where improved physical characteristics such as fire resistance, long term thermal stability, and solvent resistance are required. It is anticipated that such polymers could find uses in future long duration exploration missions as well. Their use would be even more advantageous if self-healing capability or mechanisms could be incorporated into these polymers. Such innovative approaches are currently being studied at the NASA Kennedy Space Center for use in high performance wiring systems or inflatable and habitation structures. Self-healing or self-sealing capability would significantly reduce maintenance requirements, and increase the safety and reliability performance of the systems into which these polymers would be incorporated. Many unique challenges need to be overcome in order to incorporate a self-healing mechanism into flexible, high performance polymers. Significant research into the incorporation of a self-healing mechanism into structural composites has been carried out over the past decade by a number of groups, notable among them being the University of I1linois [I]. Various mechanisms for the introduction of self-healing have been investigated. Examples of these are: 1) Microcapsule-based healant delivery. 2) Vascular network delivery. 3) Damage induced triggering of latent substrate properties. Successful self-healing has been demonstrated in structural epoxy systems with almost complete reestablishment of composite strength being achieved through the use of microcapsulation technology. However, the incorporation of a self-healing mechanism into a system in which the material is flexible, or a thin film, is much more challenging. In the case of using microencapsulation, healant core content must be small enough to reside in films less than 0.1 millimeters thick, and must overcome significant capillary and surface tension forces to flow, mix and react to achieve healing. Vascular networks small enough to fit into such films must also overcome these same flow limitations. Self-healing has also been demonstrated in ionomeric substrates such as Surlyn , wherein the heat generated by a projectile impact triggers the latent ability of this substrate to flow back to its original shape. Recent work using Diels-Alder reactions have shown promise in bringing about actual reforming of broken chemical bonds to achieve self-healing [2]. All self-healing mechanisms that rely on the use of inherent latent substrate properties require some degree of polymer chain flow to achieve any significant level of healing.

Jolley, Scott T.; Williams, Martha K.; Gibson, Tracy L.; Caraccio, Anne J.

2011-01-01

119

An advanced algorithm for highway pavement fissure detection  

NASA Astrophysics Data System (ADS)

This paper presents image detection method of pavement crack based on fractal dimension feature and designs self-adapting algorithm of fractal dimension interval of pavement region. Through image pretreatment, calculation of fractal dimension, self-adapting calculation of dimension interval, we obtain the location image of damage pavement. The experimental results of transverse crack, longitudinal crack, net-shaped crack, pit slot are contrast with that of Sobel operator. The results show that they have the similar capability on the representation of crack, but the proposed method is more flexible on the aspect of representation of crack size and calculation of damage ratio.

Chen, Bei; Cao, Wenlun; He, Yuyao

2012-04-01

120

Pavement Thickness Design Parameter  

E-print Network

consuming · Several methods available, but design information generally the same · Terminology: #12;Pavement Thickness Design · Good design uses these parameters: ­ Soil characteristics (subgrade) ­ Soil compaction Distribution ­ HMA ­ PCC #12;Pavement Thickness Design · Soil Resilient Modulus MR ­ Property of the soil

121

Asphalt in Pavement Maintenance.  

ERIC Educational Resources Information Center

Maintenance methods that can be used equally well in all regions of the country have been developed for the use of asphalt in pavement maintenance. Specific information covering methods, equipment and terminology that applies to the use of asphalt in the maintenance of all types of pavement structures, including shoulders, is provided. In many…

Asphalt Inst., College Park, MD.

122

Advanced Self-Healing Asphalt Composites in the Pavement Performance Field: Mechanisms at the Nano Level and New Repairing Methodologies.  

PubMed

In an effort to give a global view of this field of research, in this mini-review we highlight the most recent publications and patents focusing on modified asphalt pavements that contain certain reinforcing nanoparticles which impart desirable thermal, electrical and mechanical properties. In response to the increasing cost of asphalt binder and road maintenance, there is a need to look for alternative technologies and new asphalt composites, able to self-repair, for preserving and renewing the existing pavements. First, we will focus on the self-healing property of asphalt, the evidences that support that healing takes place immediately after the contact between the faces of a crack, and how the amount of healing can be measured in both the laboratory and the field. Next we review the hypothetical mechanisms of healing to understand the material behaviour and establish models to quantify the damage-healing process. Thereafter, we outline different technologies, nanotechnologies and methodologies used for self-healing paying particular attention to embedded micro-capsules, new nano-materials like carbon nanotubes and nano-fibres, ionomers, and microwave and induction heating processes. PMID:25479339

Agzenai, Yahya; Pozuelo, Javier; Sanz, Javier; Pérez, Ignacio; Baselga, Juan

2014-12-01

123

Pavement management practices. Final report  

SciTech Connect

This synthesis will be of interest to pavement designers, maintenance engineers, and others responsible for the management of highway pavements. Information is presented on pavement management systems - the established, documented procedures used to treat all activities involved in providing and sustaining pavements in an acceptable condition. As highway agencies focus more attention on maintenance and rehabilitation of highway networks, the use of some form of a pavement management system becomes increasingly important. This report of the Transportation Research Board describes the features, applicability, and used of a pavement management system and recommends five general steps for implementing a new pavement management system or improving an existing system.

Peterson, D.E.

1987-11-01

124

Contact based analysis of asphalt pavement with the effect of aggregate angularity  

Microsoft Academic Search

Relating the performance behavior of asphalt pavement with its design parameters may provide the insight information of how to control and improve the quality of asphalt pavement. The relation must be developed in a functional form so the effect of design parameters on the overall stress–strain response of asphalt pavement then can be quantified based on a single-variable perturbation. This

Han Zhu; Julie E. Nodes

2000-01-01

125

Permeable Pavements, Green Roofs, and Cisterns  

E-print Network

Permeable Pavements, Green Roofs, and Cisterns Stormwater Treatment Practices for Low site planning and engineer- pavements, green roofs, and cisterns, are ing to reduce or prevent cooperating. #12;Permeable Pavements What are they? Permeable pavements provide alternatives to standard

Hunt, William F.

126

PAVEMENT TECHNOLOGY UPDATE This Technology Transfer Program  

E-print Network

PAVEMENT TECHNOLOGY UPDATE This Technology Transfer Program publication is funded by the Division by the University of California Pavement Research Center. The University of California Pavement Research Center Using innovative research and sound engineering principles to improve pavement structures, materials

California at Berkeley, University of

127

Pavement conference..............2 Eno award ...............................3  

E-print Network

· Pavement conference..............2 · Eno award ...............................3 · ITSO conference work with intelligent pavement, which elimi- nates the need for external sensors by enabling the pavement itself to detect vehicles. Yu cre- ates the pavement by incorporating carbon nanotubes

Minnesota, University of

128

Beneficial Use of Coal Combustion By-products in the Rehabilitation of Failed Asphalt Pavements  

Microsoft Academic Search

This study demonstrates the use of Class F fly ash in combination with lime or lime kiln dust in the full depth reclamation (FDR) of asphalt pavements. FDR, in the context of this paper, is a process of pulverizing a predetermined amount of flexible pavement that is structurally deficient, blending it with chemical additives and water, and compacting it in

Tarunjit S. Butalia; William E. Wolfe

2009-01-01

129

Full Depth Reclamation of Asphalt Pavements Using Class F Fly Ash  

Microsoft Academic Search

This study demonstrates the use of Class F fly ash in combination with lime or lime kiln dust in the full depth reclamation (FDR) of asphalt pavements. FDR is a process of pulverizing a predetermined amount of flexible pavement that is structurally deficient, blending it with chemical additives and water, and compacting it in place to construct a new stabilized

Jeffryes Chapman; Wei Tu; Behrad Zand; Tarunjit Butalia

130

Pervious Pavement System Evaluation  

EPA Science Inventory

Porous pavement is a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete pavers as a popular implementation. The pavers themselves are impermeable, but the spaces between the pavers are backfilled with washed, grade...

131

Flexible electronics: high-performance magnetic sensorics for printable and flexible electronics (adv. Mater. 5/2015).  

PubMed

High-performance giant magnetoresistive (GMR) sensorics are realized by D. Karnaushenko, D. Makarov, and co-workers on page 880. These devices are printed at predefined locations on flexible circuitry. The printed magnetosensors remain fully operational over the complete consumer temperature range and reveal a GMR up to 37% and a sensitivity of 0.93 T(-1) at 130 mT. With these specifications, printed magnetoelectronics can be controlled using flexible active electronics for the realization of smart packaging and energy-efficient switches. PMID:25645075

Karnaushenko, Daniil; Makarov, Denys; Stöber, Max; Karnaushenko, Dmitriy D; Baunack, Stefan; Schmidt, Oliver G

2015-02-01

132

Platypus: Design and Implementation of a Flexible High Performance Object Store.  

E-print Network

Platypus: Design and Implementation of a Flexible High Performance Object Store. Zhen He1, Stephen. This paper reports the design and implementation of Platypus, a trans- actional object store. The twin goals of flexibility and performance dominate the design of Platypus. The design includes: support for SMP concurrency

He, Zhen

133

The impact of geology on the performance of a bituminous surfaced pavement—a case study from southeastern Nigeria  

NASA Astrophysics Data System (ADS)

One of the multi-million Naira dual carriageways in Nigeria, the Enugu-Port Harcourt expressway, has continued to experience failure at some sections, namely the stretches covering Lokpaukwu, Lokpanta, and Leru. This road section which, unlike others, does not respond to regular and routine maintenance, is concentrated on one geologic formation, the Eze Aku Shale which has been intruded by a dolerite sill. The emplacement of the dolerite sill had resulted in intense fracturing of the shales in the vicinity of the intrusions which includes portions of where the express road crosses. The road problem is most severe where the dolerite sill is traced right under and across the road. There is evidence from the study that the road problem is linked to the geological/hydrogeological conditions of the area. For example, the problematic section of the road is built on a considerably jointed, fractured and weathered shale formation as a subgrade. The subgrade ultimately has low bearing capacity. The road is almost at the foot of an escarpment where there is a concentration of natural groundwater discharge. Most of the discharge zones including natural water courses are now almost blocked resulting in increased groundwater storage and rise in water table under the highway pavement. This leads to fast deterioration of the base course materials. The dolerite sill, where it crosses the road, is less than 2 m below the grade level. It impedes vertical infiltration as well as lateral groundwater flow. Thus its position with respect to the highway grade elevation leads to an almost perpetual wetting of the base and sub-base materials.

Okagbue, C. O.; Uma, K. O.

134

Functionality enhancement of industrialized optical fiber sensors and system developed for full-scale pavement monitoring.  

PubMed

Pavements always play a predominant role in transportation. Health monitoring of pavements is becoming more and more significant, as frequently suffering from cracks, rutting, and slippage renders them prematurely out of service. Effective and reliable sensing elements are thus in high demand to make prognosis on the mechanical properties and occurrence of damage to pavements. Therefore, in this paper, various types of functionality enhancement of industrialized optical fiber sensors for pavement monitoring are developed, with the corresponding operational principles clarified in theory and the performance double checked by basic experiments. Furthermore, a self-healing optical fiber sensing network system is adopted to accomplish full-scale monitoring of pavements. The application of optical fiber sensors assembly and self-healing network system in pavement has been carried out to validate the feasibility. It has been proved that the research in this article provides a valuable method and meaningful guidance for the integrity monitoring of civil structures, especially pavements. PMID:24854060

Wang, Huaping; Liu, Wanqiu; He, Jianping; Xing, Xiaoying; Cao, Dandan; Gao, Xipeng; Hao, Xiaowei; Cheng, Hongwei; Zhou, Zhi

2014-01-01

135

Incorporating uncertainty in the Life Cycle Cost Analysis of pavements  

E-print Network

Life Cycle Cost Analysis (LCCA) is an important tool to evaluate the economic performance of alternative investments for a given project. It considers the total cost to construct, maintain, and operate a pavement over its ...

Swei, Omar Abdullah

2012-01-01

136

Mechanical analysis of a mixed mode debonding test for "composite" pavements A. Chabot*, M. Hun, F. Hammoum  

E-print Network

Mechanical analysis of a mixed mode debonding test for "composite" pavements A. Chabot*, M. Hun, F" pavements, a four-point bending test on bi-layer structures is performed. Before mixed mode failure debonding, modeling, composite pavement, four-point bending test. 1. Introduction To ensure a long lasting

Paris-Sud XI, Université de

137

Quantitative performance-based evaluation of a procedure for flexible design concept generation  

E-print Network

This thesis presents an experimental methodology for objective and quantitative design procedure evaluation based on anticipated lifecycle performance of design concepts, and a procedure for flexible design concept generation. ...

Cardin, Michel-Alexandre, 1979-

2011-01-01

138

Flexible Carbon Nanotube Films for High Performance Strain Sensors  

PubMed Central

Compared with traditional conductive fillers, carbon nanotubes (CNTs) have unique advantages, i.e., excellent mechanical properties, high electrical conductivity and thermal stability. Nanocomposites as piezoresistive films provide an interesting approach for the realization of large area strain sensors with high sensitivity and low manufacturing costs. A polymer-based nanocomposite with carbon nanomaterials as conductive filler can be deposited on a flexible substrate of choice and this leads to mechanically flexible layers. Such sensors allow the strain measurement for both integral measurement on a certain surface and local measurement at a certain position depending on the sensor geometry. Strain sensors based on carbon nanostructures can overcome several limitations of conventional strain sensors, e.g., sensitivity, adjustable measurement range and integral measurement on big surfaces. The novel technology allows realizing strain sensors which can be easily integrated even as buried layers in material systems. In this review paper, we discuss the dependence of strain sensitivity on different experimental parameters such as composition of the carbon nanomaterial/polymer layer, type of polymer, fabrication process and processing parameters. The insights about the relationship between film parameters and electromechanical properties can be used to improve the design and fabrication of CNT strain sensors. PMID:24915183

Kanoun, Olfa; Müller, Christian; Benchirouf, Abderahmane; Sanli, Abdulkadir; Dinh, Trong Nghia; Al-Hamry, Ammar; Bu, Lei; Gerlach, Carina; Bouhamed, Ayda

2014-01-01

139

POROUS PAVEMENT: RESEARCH; DEVELOPMENT; AND DEMONSTRATION  

EPA Science Inventory

This paper discusses the U.S. Environmental Protection Agency's porous pavement research program along with the economics, advantages, potential applications, and status and future research needs of porous pavements. Porous pavements are an available stormwater management techniq...

140

Asphalt pavement surfaces and asphalt mixtures. Transportation research record  

SciTech Connect

The papers in this volume, which deal with asphalt pavement surfaces and asphalt mixtures, should be of interest to state and local construction, design, materials, and research engineers as well as contractors and material producers. The papers in Part 1 include discussions of pavement smoothness specifications and skidding characteristics. The first four papers in Part 2 were submitted in response to a call for papers for a session at the 75th Annual Meeting of the Transportation Research Board on low-temperature properties of hot-mix asphalt. The next eight are on the influence of volumetric and strength properties on the performance of hot-mix asphalt. In the following three papers, the topics covered are the complex modulus of asphalt concrete, cold in-place asphalt recycling, and polymer modification of asphalt pavements in Ontario. The last two papers were presented in a session on relationship of materials characterization to accelerated pavement performance testing.

NONE

1996-12-31

141

Experimental pavement using household waste slag  

SciTech Connect

Municipal wastes used to be simply landfilled, but because of increasing difficulty in finding disposal sites, it became common practice to incinerate wastes and landfill the ash. In view of rapidly dwindling landfill sites, the author thought that the landfill site problem might be solved by finding a way to utilize slag made from incinerator ash. In this paper, a method for utilizing water-granulated slag as an asphalt pavement material is discussed. On the basis of laboratory test results, trial paving using base course materials consisting of crushed stone and 25 or 50% slag was carried out, paying attention primarily to bearing capacity. Marshall tests and fatigue resistance tests were conducted to determine the optimum content of water-granulated slag, and it was concluded that quality comparable to that of conventional asphalt concrete was attained at the slag content of 25% or less and that no problem would arise if the slag content was kept at 60% or less of the fine aggregate content. The mix proportions thus determined were also tested through experimental paving. A follow-up study to evaluate the durability of the experimental pavements confirmed that the experimental pavements were comparable in performance with conventional asphalt concrete pavements. This paper also reports on some problems encountered that need to be solved before utilizing water-granulated slag.

Kouda, Masahiro [Nippon Hodo Co., Ltd., Kasugai, Aichi (Japan). Nagoya Research Inst.] [Nippon Hodo Co., Ltd., Kasugai, Aichi (Japan). Nagoya Research Inst.

1996-12-31

142

The effect of ankle muscle strength and flexibility on dolphin kick performance in competitive swimmers.  

PubMed

The velocity of a swimmer is determined by biomechanical and bioenergetics factors. However, little is known about the effect of ankle flexibility on dolphin kick performance. Next to this, scientific evidence is lacking concerning the influence of ankle muscle strength. Therefore, the aim of this study was to investigate the effect of ankle flexibility and muscle strength on dolphin kick performance in competitive swimmers. Ankle range of motion (ROM) and ankle muscle strength were measured in 26 healthy competitive swimmers. The effect of both was assessed on the swimmer's velocity and lower extremity joint angles during three maximal dolphin kick trials. Additionally, the effect of a flexibility restriction by a tape on the dolphin kick performance was assessed. Correlations were calculated between the flexibility, muscle strength and dolphin kick performance and differences were investigated between the unrestricted and restricted condition. Muscle strength of dorsal flexors and internal rotators were positively significantly correlated with the velocity. Active and passive plantar flexion ROM and internal rotation ROM were not significantly correlated. A plantar flexion-internal rotation restriction during the dolphin kick showed a significant decrease in velocity. This restriction was associated with a changed movement pattern in the knee towards more flexion. The results suggest that dolphin kick velocity might be enhanced by ankle muscle strength exercises and that subjects with a restricted ankle flexibility might profit from a flexibility program. PMID:24984154

Willems, Tine M; Cornelis, Justien A M; De Deurwaerder, Lien E P; Roelandt, Filip; De Mits, Sophie

2014-08-01

143

Analysis of Instrumentation Selection and Placement to Monitor the Hydrologic Performance of Permeable Pavement Systems and Bioinfiltration Areas at the Edison Environmental Center in New Jersey  

EPA Science Inventory

In 2009, the U.S. Environmental Protection Agency constructed a 0.4-ha (1-ac) parking lot surfaced with three different permeable pavement types (interlocking concrete pavers, porous concrete, and porous asphalt) and six bioinfiltration areas with three different drainage area to...

144

CRACKSCOPEAUTOMATIC PAVEMENT CRACKING INSPECTION SYSTEM  

E-print Network

0-5708-P4 CRACKSCOPEAUTOMATIC PAVEMENT CRACKING INSPECTION SYSTEM Authors: Bugao Xu, Ph.D. and P/O) ................................................................................................... 11 3.1.3 Crack

Texas at Austin, University of

145

High-performance flexible organic light-emitting diodes using embedded silver network transparent electrodes.  

PubMed

Because of their mechanical flexibility, organic light-emitting diodes (OLEDs) hold great promise as a leading technology for display and lighting applications in wearable electronics. The development of flexible OLEDs requires high-quality transparent conductive electrodes with superior bendability and roll-to-roll manufacturing compatibility to replace indium tin oxide (ITO) anodes. Here, we present a flexible transparent conductor on plastic with embedded silver networks which is used to achieve flexible, highly power-efficient large-area green and white OLEDs. By combining an improved outcoupling structure for simultaneously extracting light in waveguide and substrate modes and reducing the surface plasmonic losses, flexible white OLEDs exhibit a power efficiency of 106 lm W(-1) at 1000 cd m(-2) with angular color stability, which is significantly higher than all other reports of flexible white OLEDs. These results represent an exciting step toward the realization of ITO-free, high-efficiency OLEDs for use in a wide variety of high-performance flexible applications. PMID:25470615

Zhou, Lei; Xiang, Heng-Yang; Shen, Su; Li, Yan-Qing; Chen, Jing-De; Xie, Hao-Jun; Goldthorpe, Irene A; Chen, Lin-Sen; Lee, Shuit-Tong; Tang, Jian-Xin

2014-12-23

146

Fatigue behavior of rubber modified pavements. Final report, 1994-1996  

SciTech Connect

Over the last 15 years, a number of rubberized pavement projects have been built in Alaska. Initial laboratory and field investigations sponsored by the Alaska Department of Transportation and Public Facilities (AKDOT&PF) and conducted by Raad et al. (1995) indicated improved fatigue performance of the rubberized sections in comparison with conventional asphalt concrete pavements. The report presents the results of a follow-up investigation to develop design equations for rubberized pavements in Alaska.

Raad, L.; Saboundjian, S.

1997-05-01

147

Improvement of performance and flexibility for photovoltaic module using individual DC\\/DC converter  

Microsoft Academic Search

This paper focuses on the improvement of performance for PV generators in nonideal conditions and proposes topologies to minimize the degradation of performance caused by these conditions. It also presents a flexible PV module concept which consists of paralleling DC\\/DC converters with maximum power tracking (MPPT) and power balance functions. Optimum power configuration and balance of the paralleling modules system

Wei Yao; Mingzhi Gao; Zheng Ren; Min Chen; Zhaoming Qian

2009-01-01

148

Cloud Impacts on Pavement Temperature in Energy Balance Models  

NASA Astrophysics Data System (ADS)

Forecast systems provide decision support for end-users ranging from the solar energy industry to municipalities concerned with road safety. Pavement temperature is an important variable when considering vehicle response to various weather conditions. A complex, yet direct relationship exists between tire and pavement temperatures. Literature has shown that as tire temperature increases, friction decreases which affects vehicle performance. Many forecast systems suffer from inaccurate radiation forecasts resulting in part from the inability to model different types of clouds and their influence on radiation. This research focused on forecast improvement by determining how cloud type impacts the amount of shortwave radiation reaching the surface and subsequent pavement temperatures. The study region was the Great Plains where surface solar radiation data were obtained from the High Plains Regional Climate Center's Automated Weather Data Network stations. Road pavement temperature data were obtained from the Meteorological Assimilation Data Ingest System. Cloud properties and radiative transfer quantities were obtained from the Clouds and Earth's Radiant Energy System mission via Aqua and Terra Moderate Resolution Imaging Spectroradiometer satellite products. An additional cloud data set was incorporated from the Naval Research Laboratory Cloud Classification algorithm. Statistical analyses using a modified nearest neighbor approach were first performed relating shortwave radiation variability with road pavement temperature fluctuations. Then statistical associations were determined between the shortwave radiation and cloud property data sets. Preliminary results suggest that substantial pavement forecasting improvement is possible with the inclusion of cloud-specific information. Future model sensitivity testing seeks to quantify the magnitude of forecast improvement.

Walker, C. L.

2013-12-01

149

Balancing performance, robustness and flexibility in routing systems  

Microsoft Academic Search

Modern networks face the daunting task of handling increas- ingly diverse traffic that is displaying a growing intolerance to disruptions. This has given rise to many initiatives, and in this paper we focus on multiple topology routing as the primary vehicle for meeting those demands. Specifically, we seek routing solutions capable of not just accommodat- ing different performance goals, but

Kin-Wah Kwong; Roch Guérin; Anees Shaikh; Shu Tao

2008-01-01

150

International Symposium on Pavement LCA (Pavement LCA 2014) TRB Co-Sponsored  

E-print Network

International Symposium on Pavement LCA (Pavement LCA 2014) TRB Co-Sponsored (Sustainable Pavements AFD00(1)) FHWA Co-Sponsored (Sustainable Pavement Task Group) Location: UC Davis Campus Conference Assessment (LCA) for pavements. The workshop will be coordinated with activities of the FWHA Sustainable

California at Davis, University of

151

Combined Effect of Moving Wheel Loading and Three-Dimensional Contact Stresses on Perpetual Pavement Responses  

Microsoft Academic Search

Tire–pavement interaction was analyzed with measured three-dimensional (3-D) tire contact stresses at various load levels (35, 44, and 53 kN) and constant tire pressure (720 kPa). The combined effect of moving wheel load and 3-D contact stresses on flexible pavement response was evaluated with a developed 3-D finite element (FE) model, which incorporated the measured 3-D tire contact stresses, hot-mix

Hao Wang; Imad L. Al-Qadi

2009-01-01

152

Registered nurse-performed flexible sigmoidoscopy in Ontario: Development and implementation of the curriculum and program  

PubMed Central

Although colorectal cancer is a leading cause of death in Canada, it is curable if detected in the early stages. Flexible sigmoidoscopy has been shown to reduce the incidence and mortality of colorectal cancer in patients who are at average risk for this disease and, therefore, is an appropriate screening intervention. Moreover, it may be performed by nonphysicians. A program to enable registered nurses to perform flexible sigmoidoscopy to increase colorectal cancer screening capacity in Ontario was developed. This program incorporated practical elements learned from other jurisdictions as well as specific regional considerations to fit within the health care system of Ontario. The nurses received structured didactic and simulation training before performing sigmoidoscopies on patients under physician supervision. After training, nurses were evaluated by two assessors for their ability to perform complete sigmoidoscopies safely and independently. To date, 17 nurses have achieved independence in performing flexible sigmoidoscopy at 14 sites. In total, nurses have screened >7000 Ontarians, with a cancer detection rate of 5.1 per 1000 screened, which is comparable with rates in other jurisdictions and with sigmoidoscopy performed by gastroenterologists, surgeons and other trained nonphysicians. We have shown, therefore, that with proper training and program structure, registered nurses are able to perform flexible sigmoidoscopy in a safe and thorough manner resulting in a significant increase in access to colorectal cancer screening. PMID:24416735

Cooper, Mary Anne; Tinmouth, Jill Margaret; Rabeneck, Linda

2014-01-01

153

Shakedown Analysis of Road Pavements  

Microsoft Academic Search

Shakedown behaviour of road pavements was investigated in laboratory controlled conditions using the Sydney University Pavement Testing Facility. Wheel loads lower than the shakedown load generated low permanent deformations for a larger number of load cycles in comparison with high permanent deformations for a lower number of load cycles for wheel loads higher than the shakedown load. Computer software was

P. S. Ravindra

154

Summary of Concrete Overlays Existing concrete pavement  

E-print Network

Summary of Concrete Overlays Existing concrete pavement with surface distresses Prepared surface Monolithic pavement with new concrete surface Existing asphalt pavement with surface distresses Milled pavement with asphalt surface distresses Milled and cleaned surface New 2­5 in. (5.1­12.7 cm) bonded

155

Recommended Practice for Accepting New Concrete Pavement  

E-print Network

Recommended Practice for Accepting New Concrete Pavement Surfaces for Tire/Pavement Noise Designation: CPSCP PP 1-11 (rev 3/1/2011) National Concrete Pavement Technology Center 2711 South Loop Drive, Suite 4700 Ames, IA 50010 #12;PP 1-1 CPSCP Recommended Practice for Accepting New Concrete Pavement

156

Life Cycle Assessment of Reclaimed Asphalt Pavement  

E-print Network

Life Cycle Assessment of Reclaimed Asphalt Pavement to Improve Asphalt Pavement Sustainability By-melt old binder on the RAP #12;Life Cycle Assessment (LCA) · #12;Asphalt Pavement Life Cycle Road-filled after use #12;Asphalt Pavement Life Cycle Road Construction Aggregates Additives Bitumen Down- Cycled

Minnesota, University of

157

Environmental performance and mechanical analysis of concrete containing recycled asphalt pavement (RAP) and waste precast concrete as aggregate.  

PubMed

The overall objective of this research project was to investigate the feasibility of incorporating 100% recycled aggregates, either waste precast concrete or waste asphalt planning, as replacements for virgin aggregates in structural concrete and to determine the mechanical and environmental performance of concrete containing these aggregates. Four different types of concrete mixtures were designed with the same total water cement ratio (w/c=0.74) either by using natural aggregate as reference or by totally replacing the natural aggregate with recycled material. Ground granulated blast furnace slag (GGBS) was used as a mineral addition (35%) in all mixtures. The test results showed that it is possible to obtain satisfactory performance for strength characteristics of concrete containing recycled aggregates, if these aggregates are sourced from old precast concrete. However, from the perspective of the mechanical properties, the test results indicated that concrete with RAP aggregate cannot be used for structural applications. In terms of leaching, the results also showed that the environmental behaviour of the recycled aggregate concrete is similar to that of the natural aggregate concrete. PMID:24316812

Erdem, Sava?; Blankson, Marva Angela

2014-01-15

158

High Performance of Ultralow Temperature Polycrystalline Silicon Thin Film Transistor on Flexible Metal Foil Substrate  

NASA Astrophysics Data System (ADS)

A high performance ultralow temperature polycrystalline silicon (poly-Si) thin film transistor (TFT) was obtained on a flexible metal foil substrate using the optimization of a benzocyclobutene (BCB) planarization process for a rough flexible metal foil substrate surfaces, the high quality SiO2 interface layer formation between the gate dielectric film and the poly-Si film using plasma oxidation, and a successful crystallization of large grain poly-Si films with a sequential lateral solidification (SLS) method. High performances with field effect mobilities of 196 and 95 cm2 V-1 s-1, threshold voltages of 1.6 and -1.5 V and sub-threshold swings of 0.53 and 0.45 V/decade were obtained for n-channel metal-oxide-semiconductor (nMOS) and p-channel metal-oxide-semiconductor (pMOS) TFT on flexible metal foil substrate, respectively.

Dong Jin Park,; Byung Ok Park,

2010-05-01

159

Pavement recycling. Executive summary and report  

SciTech Connect

The Federal Highway Administration (FHWA) initiated Demonstration Project 39 (DP 39) Recycling Asphalt Pavements in June 1976. The project showed that asphalt pavement recycling was a technically viable rehabitation technique, and it was estimated that the use of reclaimed asphalt pavement (RAP) would amount to approximately 15 percent of the total hot-mix asphalt (HMA) production by the mid-1980s. It was expected that most of the asphalt pavement removed would be reused in new pavement construction or overlays.

NONE

1995-10-01

160

Numerical study on the power extraction performance of a flapping foil with a flexible tail  

NASA Astrophysics Data System (ADS)

The numerical study on the power extraction performance of a flapping foil with a flexible tail is performed in this work. A NACA0015 airfoil is arranged in a two-dimensional laminar flow and imposed with a synchronous harmonic plunge and pitch rotary motion. A flat plate that is attached to the trailing edge of the foil is utilized to model a tail, and so they are viewed as a whole for the purpose of power extraction. In addition, the tail either is rigid or can deform due to the exerted hydrodynamic forces. To implement numerical simulations, an immersed boundary-lattice Boltzmann method is employed. At a Reynolds number of 1100 and the position of the pitching axis at third chord, the influences of the mass and flexibility of the tail as well as the frequency of motion on the power extraction are systematically examined. It is found that compared to the foil with a rigid tail, the efficiency of power extraction for the foil with a deformable tail can be improved. Based on the numerical analysis, it is indicated that the enhanced plunging component of the power extraction, which is caused by the increased lift force, directly contributes to the efficiency improvement. Since a flexible tail with medium and high masses is not beneficial to the efficiency improvement, a flexible tail with low mass together with high flexibility is recommended in the flapping foil based power extraction system.

Wu, J.; Shu, C.; Zhao, N.; Tian, F.-B.

2015-01-01

161

Automated pavement crack detection  

E-print Network

of the number and orientation of the edges detected in the windows yields a classification of the crack type. The extent of the cracking is calculated by the total number of cracks found in the pavement section. To my parents. ACKNOWLEDGMENTS I wish... and Unimodal III IMAGE ANALYSIS . . A. Projection Histogram B. Error Analysis on Window Size and Shape Factor 1. Shape Factor 2. Window Size C. Classification Rule 1. Two-Direction Algorithm 2. Four-Direction Algorithm 3. Eight-Direction Algorithm . D...

Rao, Ashok Madhava

2012-06-07

162

Mairepav 6 : the Sixth International Conference on maintenance and rehabilitation of pavements and technological control, At Torino, Italy, July 8-10, 2009  

E-print Network

Mairepav 6 : the Sixth International Conference on maintenance and rehabilitation of pavements as the basics (Cormier & Thébeau 2003) for choosing types of pavement. In that context, many studies have been of pavements. LCPC has performed several studies based on LCA, with the aim of developing a method suitable

Paris-Sud XI, Université de

163

Nondestructive Test Methods for Rapid Assessment of Flexible Base Performance in Transportation Infrastructures  

E-print Network

NONDESTRUCTIVE TEST METHODS FOR RAPID ASSESSMENT OF FLEXIBLE BASE PERFORMANCE IN TRANSPORTATION INFRASTRUCTURES A Dissertation by HAKAN SAHIN Submitted to the Office of Graduate and Professional Studies of Texas A&M University in partial... ........................................................................ 167 9.5 Closure ......................................................................................................... 173 10. A FIELD VERIFICATION BY USING NONDESTRUCTIVE TESTS .............. 175 10.1 Introduction...

Sahin, Hakan

2014-08-14

164

Small-scale accelerated pavement testing  

SciTech Connect

This paper presents the results of a study conducted to explore the use of small-scale models of accelerated pavement testing (APT) devices to evaluate the performance of pavements in conjunction with full-scale tests. The motivation for the study was the availability of a model mobile load simulator (MMLS), which had been built originally to illustrate the operation of the full-scale mobile load simulator (MLS) under design at the time. The scaling requirements will be different depending on whether dynamic (inertia), viscous, or gravity effects are important. One must thus decide which one of these effects controls the behavior to try to reproduce it exactly. In the preliminary tests conducted with the MMLS, emphasis had been placed in reproducing accurately the viscoelastic behavior of the asphalt layer. The possibility of obtaining valid results, even if similitude is not maintained in relation to inertia forces, is explored in this paper. The effects of load frequency or velocity and the effects of layer thicknesses are studied. The total thickness of the model pavement, which must be finite, and its effects on displacements and strains are also considered. It is concluded that even when full similitude is not satisfied it is possible to obtain valid results that can be extrapolated to predict prototype performance if one were interested primarily in the behavior of the asphalt layer. Preliminary analyses should be conducted, however, to guide on the selection of the model dimensions.

Kim, S.M. [Korea Highway Corp., Kyunggi (Korea, Republic of). Highway Research Inst.; Hugo, F. [Univ. of Stellenbosch (South Africa). Inst. for Transport Technology; Roesset, J.M. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering

1998-03-01

165

Pervious Pavement System Evaluation- Abstract  

EPA Science Inventory

Porous pavement is a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete pavers as a popular implementation. The pavers themselves are impermeable, but the spaces between the pavers are backfilled with washed, gra...

166

Acute effects of different volumes of dynamic stretching on vertical jump performance, flexibility and muscular endurance.  

PubMed

The purpose of this study was to examine the acute effects of different volumes of a dynamic stretching routine on vertical jump (VJ) performance, flexibility and muscular endurance (ME). Twenty-six males (age 22.2 ± 1.3 years) performed three separate randomized conditions: (i) a control (CON) condition (5-min jog + 12 min of resting), (ii) a 5-min jog + a dynamic stretching routine (DS1; 6.7 ± 1.3 min) and (iii) a 5-min jog + a dynamic stretching routine with twice the volume (DS2; 12.1 ± 1.6 min). The dynamic stretching routine included 11 exercises targeting the hip and thigh musculature. VJ performance (jump height and velocity) and flexibility were measured prior to and following all conditions, while ME was measured following all conditions. The DS1 and DS2 conditions increased VJ height and velocity (P<0.01), while the CON condition did not change (P>0.05). When compared to the CON condition, the DS1 condition did not improve ME (P>0.05), whereas the DS2 condition resulted in a significant (15.6%) decrease in the number of repetitions completed (P<0.05). Flexibility increased following all conditions (P<0.01), while the DS1 condition was significantly greater (P<0.01) than the CON condition at post-testing. These results suggest that dynamic stretching routines lasting approximately 6-12 min performed following a 5-min jog resulted in similar increases in VJ performance and flexibility. However, longer durations of dynamic stretching routines may impair repetitive high-intensity activities. PMID:24438386

Ryan, Eric D; Everett, Kenneth L; Smith, Doug B; Pollner, Christie; Thompson, Brennan J; Sobolewski, Eric J; Fiddler, Ryan E

2014-11-01

167

GPR used in combination with other NDT methods for assessing pavements in PPP projects  

NASA Astrophysics Data System (ADS)

In the recent decades, Public-Private Partnerships (PPP) has been adopted for highway infrastructure procurement in many countries. PPP projects typically take the form of a section of highway and connecting roadways which are to be construction and managed for a given concession period. Over the course of the highway concession period, the private agency takes over the pavement maintenance and rehabilitation duties. On this purpose, it is critical to find the most cost effective way to maintain the infrastructure in compliance with the agreed upon performance measures and a Pavement Management Systems (PMS) is critical to the success of this process. For the prosperous operation of a PMS it is necessary to have appropriate procedures for pavement monitoring and evaluation, which is important in many areas of pavement engineering. Non Destructive Testing (NDT) has played a major role in pavement condition monitoring, assessments and evaluation accomplishing continuous and quick collection of pavement data. The analysis of this data can lead to indicators related to trigger values (criteria) that define the pavement condition based on which the pavement "health" is perceived helping decide whether there is the need or not to intervene in the pavement. The accomplished perception appoints required management activities for preserving pavements in favor not only of the involved highway/road agencies but also of users' service. Amongst NDT methods Ground Penetrating Radar (GPR) seems to be a very powerful toll, as it provides a range of condition and construction pavement information. It can support effectively the implementation of PMS activities in the framework of pavement monitoring and evaluation. Given that, the present work aims to the development and adaptation of a protocol for the use of GPR in combination with other NDT methods, such as Falling Weight Deflectometer (FWD), for assessing pavements in PPP projects. It is based on the experience of Laboratory of Pavement Engineering of National Technical University of Athens (NTUA) gained through its research activities in various Greek PPP projects as well its involvement in several related European and International scientific actions. It is suggested that the implementation of such protocol could support the pavement management activities with respect to the needs of a PPP project. This is accomplished through the resulted advantages that include simplicity in application, economic benefits and familiarity that are very important factors towards the optimization of the resources and the utilization of the available information; both of them are required for the orderly operation of a PPP project. Acknowledgments: This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

Loizos, Andreas; Plati, Christina

2014-05-01

168

Design of High Performance Fuzzy Controllers Using Flexible Parameterized Membership Functions and Intelligent Genetic Algorithms  

NASA Astrophysics Data System (ADS)

This paper proposes a method for designing high performance fuzzy controllers with a compact rule system. The method is mainly derived from flexible parameterized membership functions (FPMFs) and an intelligent genetic algorithm (IGA) which is superior to the traditional GAs in solving large parameter optimization problems. An FPMF consists of flexible trapezoidal fuzzy sets that the fuzzy set is encoded using five parameters. Furthermore, the membership functions and fuzzy rules are simultaneously determined by effectively encoding all the system parameters into chromosomes. Therefore, the optimal design of fuzzy controllers is formulated as a large parameter optimization problem, which can be effectively solved by IGA. The proposed method is demonstrated by two well-known problems, truck backing and cart centering problems. It is shown empirically that the performance of the proposed method is superior to those of existing methods in terms of the numbers of time steps and fuzzy rules.

Ho, Shinn-Ying; Ho, Shinn-Jang; Chen, Tai-Kang

169

High-performance flexible thin-film transistors exfoliated from bulk wafer.  

PubMed

Mechanically flexible integrated circuits (ICs) have gained increasing attention in recent years with emerging markets in portable electronics. Although a number of thin-film-transistor (TFT) IC solutions have been reported, challenges still remain for the fabrication of inexpensive, high-performance flexible devices. We report a simple and straightforward solution: mechanically exfoliating a thin Si film containing ICs. Transistors and circuits can be prefabricated on bulk silicon wafer with the conventional complementary metal-oxide-semiconductor (CMOS) process flow without additional temperature or process limitations. The short channel MOSFETs exhibit similar electrical performance before and after exfoliation. This exfoliation process also provides a fast and economical approach to producing thinned silicon wafers, which is a key enabler for three-dimensional (3D) silicon integration based on Through Silicon Vias (TSVs). PMID:23092185

Zhai, Yujia; Mathew, Leo; Rao, Rajesh; Xu, Dewei; Banerjee, Sanjay K

2012-11-14

170

Improving a pavement-watering method on the basis1 of pavement surface temperature measurements2  

E-print Network

Improving a pavement-watering method on the basis1 of pavement surface temperature measurements2.hendel@paris.fr)8 Abstract: Pavement-watering has been studied since the 1990's and is currently considered a9 water resource availability problems require that water consumption be optimized. Although11 pavement

Paris-Sud XI, Université de

171

Effects of flexibility on AGS performance. [Annular suspension pointing system Gimbal System aboard Shuttle Orbiter  

NASA Technical Reports Server (NTRS)

The Marshall Space Flight Center has had under development the Annular Suspension Pointing System Gimbal System (AGS) since early 1979. The AGS is an Orbiter cargo bay mounted subarcsecond 3 axis inertial pointer that can accommodate a wide range of payloads which require more stringent pointing than the Orbiter can provide. This paper will describe the AGS, state performance requirements and the control law configuration. Then an approach to investigating the flexible body effects on control system design will be discussed.

Shelton, H. L.; Cunningham, D. C.; Worley, H. E.; Seltzer, S. M.

1982-01-01

172

Investigation of factors affecting asphalt pavement recycling and asphalt compatibility  

SciTech Connect

Both economic and environmental factors dictate that asphalt pavement be recycled. Many recycling projects have been completed using a variety of recycling additives, but little work has been done on the physiochemical aspects of pavement recycling. The present exploratory study was undertaken to better define the physiochemical variables of recycling. Objectives of the present study include: (1) to determine if molecular structuring in the asphalt binder could be observed in oxidized (air-aged) asphalt-aggregate briquets, and if so, how was structuring affected during briquits, and if so, how was structuring affected during briquet recycling and (2) to determine if recycling agents penetrate the strongly adsorbed asphalt layer on the aggregate surface. Differences were seen in asphalt component compatibility as judged by the state of peptization parameters. In extreme cases the values of the parameters correlated with properties of asphalts of known compatibility; however, a relationship between the parameters determined on a series of asphalts in pavements was not established. The parameters might be useful in evaluating additives for pavement recycling; however, more systems need to be studied to fully assess their potential usefulness. Finally, the parameters need to be correlated with performance-related measurements such as asphalt rheological and mix properties. Examination of the parameters and their changes on asphalt oxidative aging may also be informative with regard to asphalt durability inasmuch as oxidation-induced changes are a major cause of asphalt pavement failure.

Venable, R.L.; Petersen, J.C.; Robertson, R.E.; Plancher, H.

1983-03-01

173

High Performance, Robust Control of Flexible Space Structures: MSFC Center Director's Discretionary Fund  

NASA Technical Reports Server (NTRS)

Many spacecraft systems have ambitious objectives that place stringent requirements on control systems. Achievable performance is often limited because of difficulty of obtaining accurate models for flexible space structures. To achieve sufficiently high performance to accomplish mission objectives may require the ability to refine the control design model based on closed-loop test data and tune the controller based on the refined model. A control system design procedure is developed based on mixed H2/H(infinity) optimization to synthesize a set of controllers explicitly trading between nominal performance and robust stability. A homotopy algorithm is presented which generates a trajectory of gains that may be implemented to determine maximum achievable performance for a given model error bound. Examples show that a better balance between robustness and performance is obtained using the mixed H2/H(infinity) design method than either H2 or mu-synthesis control design. A second contribution is a new procedure for closed-loop system identification which refines parameters of a control design model in a canonical realization. Examples demonstrate convergence of the parameter estimation and improved performance realized by using the refined model for controller redesign. These developments result in an effective mechanism for achieving high-performance control of flexible space structures.

Whorton, M. S.

1998-01-01

174

Pervious Pavement System Evaluation-Poster  

EPA Science Inventory

Pervious pavement is a low impact development stormwater control. The Environmental Protection Agency's Urban Watershed Management Branch is evaluating interlocking concrete pavingstone pervious pavement systems. The pavingstones themselves are impermeable, but the spaces between...

175

Effects of acute lipid overload on skeletal muscle insulin resistance, metabolic flexibility, and mitochondrial performance.  

PubMed

We hypothesized that acute lipid-induced insulin resistance would be attenuated in high-oxidative muscle of lean trained (LT) endurance athletes due to their enhanced metabolic flexibility and mitochondrial capacity. Lean sedentary (LS), obese sedentary (OS), and LT participants completed two hyperinsulinemic euglycemic clamp studies with and without (glycerol control) the coinfusion of Intralipid. Metabolic flexibility was measured by indirect calorimetry as the oxidation of fatty acids and glucose during fasted and insulin-stimulated conditions, the latter with and without lipid oversupply. Muscle biopsies were obtained for mitochondrial and insulin-signaling studies. During hyperinsulinemia without lipid, glucose infusion rate (GIR) was lowest in OS due to lower rates of nonoxidative glucose disposal (NOGD), whereas state 4 respiration was increased in all groups. Lipid infusion reduced GIR similarly in all subjects and reduced state 4 respiration. However, in LT subjects, fat oxidation was higher with lipid oversupply, and although glucose oxidation was reduced, NOGD was better preserved compared with LS and OS subjects. Mitochondrial performance was positively associated with better NOGD and insulin sensitivity in both conditions. We conclude that enhanced mitochondrial performance with exercise is related to better metabolic flexibility and insulin sensitivity in response to lipid overload. PMID:25352435

Dubé, John J; Coen, Paul M; DiStefano, Giovanna; Chacon, Alexander C; Helbling, Nicole L; Desimone, Marisa E; Stafanovic-Racic, Maja; Hames, Kazanna C; Despines, Alex A; Toledo, Frederico G S; Goodpaster, Bret H

2014-12-15

176

Flexible thick-film glucose biosensor: influence of mechanical bending on the performance.  

PubMed

The influence of the bending-induced mechanical stress of flexible Nafion/GOx/carbon screen-printed electrodes (SPEs) upon the performance of such glucose biosensors has been examined. Surprisingly, such flexible enzyme/polymer-SPEs operate well following a severe bending-induced mechanical stress (including a 180 degrees pinch), and actually display a substantial sensitivity enhancement following their mechanical bending. The bending-induced sensitivity enhancement is observed only for the amperometric detection of the glucose substrate but not for measurements of hydrogen peroxide, catechol or ferrocyanide at coated or bare SPEs. These (and additional) data indicate that the bending effect is associated primarily with changes in the biocatalytic activity. Such sensitivity enhancement is more pronounced at elevated glucose levels, reflecting the bending-induced changes in the biocatalytic reaction. Factors affecting the bending-induced changes in the performance are examined. While our data clearly indicate that flexible enzyme/polymer-SPEs can tolerate a severe mechanical stress and hold promise as wearable glucose biosensors, delivering the sample to the active sensor surface remains the major challenge for such continuous health monitoring. PMID:20188880

Chuang, Min-Chieh; Yang, Yang-Li; Tseng, Ta-Feng; Chou, Tzuyang; Lou, Shyh-Liang; Wang, Joseph

2010-04-15

177

Plasmonic photosensitization of polyaniline prepared by a novel process for high-performance flexible photodetector.  

PubMed

We report the synthesis of a polyaniline (PAni)-gold nanoparticle (AuNP) composite thin film in a single step. A flexible high-performance visible photodetector is constructed using PAni-AuNP composite with low loading of AuNP, and optoelectronic properties of the device are evaluated. The present study demonstrates that a plasmonic hybrid nanocomposite prepared by a single-step novel plasma-based dry process could solve the low lifetime and performance-related issues of organic optoelectronic devices. PMID:25604046

Barman, Tapan; Pal, Arup R

2015-02-01

178

Flexible high-performance all-inkjet-printed inverters: organo-compatible and stable interface engineering.  

PubMed

High-performance all-inkjet-printed organic inverters are fabricated on flexible substrates. By introducing end-functionalized polystyrene on both surfaces of inkjet-printed source/drain Ag electrodes and poly(4-vinylphenol) dielectrics, organic-compatible and hydroxyl-free interfaces between those layers and 6,13-bis(triisopropylsilylethynyl)pentacene drastically reduce the interfacial trap and contact resistance. The resulting organic inverters show a full up-down switching performance and a high voltage gain of 19.8. PMID:23828137

Chung, Seungjun; Jang, Mi; Ji, Seon-Beom; Im, Hwarim; Seong, Narkhyeon; Ha, Jewook; Kwon, Soon-Ki; Kim, Yun-Hi; Yang, Hoichang; Hong, Yongtaek

2013-09-14

179

Pavement recycling guidelines for state and local governments: Participant`s reference book. Final report, September 1995--December 1997  

SciTech Connect

Recycling or reuse of existing asphalt pavement materials to produce new pavement materials has the following advantages: (1) reduced costs of construction, (2) conservation of aggregate and binder, (3) preservation of the existing pavement geometrics, (4) preservation of the environment, and (5) conservation of energy. This document was prepared to provide the following information on recycling of asphalt pavements: (1) performance data, (2) legislation/specification limits, (3) selection of pavement for recycling and recycling strategies, (4) economics of recycling, and (5) structural design of recycled pavements. The following recycling methods have been included: hot-mix asphalt recycling (both batch and drum plants), asphalt surface recycling, hot-in-place recycling, cold-mix asphalt recycling, and full depth reclamation. Materials and mix design, construction methods and equipment, case histories and quality control/quality assurance have been discussed for all recycling methods.

Kandhal, P.S.; Mallick, R.B.

1997-12-01

180

Further development of surface metrology methods for predicting the functional performance of flexible photovoltaic barrier films  

NASA Astrophysics Data System (ADS)

Surface topography analysis plays a very significant role in determining the functional performance for many engineering surfaces. In this paper, feature characterization techniques, based on the ‘wolf pruning’ method are implemented to characterize micro and nano-scale features which have a dominant effect on the functional lifespan of flexible photovoltaic (PV) modules. The densities and dimensions of the potential significant features are calculated by means of the feature ‘characterization toolbox’. The outcome of this study has shown the potential of areal feature segmentation for detecting functionally significant defects present in atomic layer deposition barrier coatings of Al2O3 on polymer films. The analysis provides the basis for the development in process metrology for roll-to-roll production of barrier coatings as applied to flexible PV arrays and is a first step in the demonstration of in-process use of feature parameters.

Elrawemi, M.; Blunt, L.; Fleming, L.; Sweeney, F.

2013-09-01

181

Making "Magic" Sidewalks of Pervious Pavement  

NSDL National Science Digital Library

Students use everyday building materials—sand, pea gravel, cement and water—to create and test pervious pavement. They learn what materials make up a traditional, impervious concrete mix and how pervious pavement mixes differ. Groups are challenged to create their own pervious pavement mixes, experimenting with material ratios to evaluate how infiltration rates change with different mix combinations.

Water Awareness Research and Education (WARE) Research Experience for Teachers (RET),

182

Sustainable Concrete Pavements: A Manual of Practice  

E-print Network

#12;#12;#12;Sustainable Concrete Pavements: A Manual of Practice January 2012 TECHNICAL EDITORS Dr. Peter Taylor, Associate Director National Concrete Pavement Technology Center, Iowa State and Sustainability Group, Applied Pavement Technology) CO-AUTHORS Dr. Tom Van Dam, Principal Engineer, CTLGroup

183

Pavement thickness evaluation using ground penetrating radar  

Microsoft Academic Search

Accurate knowledge of pavement thickness is important information to have both at a network and project level. This information aids in pavement management and design. Much of the time this information is missing, out of date, or unknown for highway sections. Current technologies for determining pavement thickness are core drilling, falling weight deflectometer (FWD), and ground penetrating radar (GPR). Core

Dwayne Arthur Harris

2006-01-01

184

Fatigue properties of rubber modified pavements. Final report  

SciTech Connect

This report presents results of a study to determine the fatigue behavior of rubber modified pavements in Alaska in comparison with conventional asphalt concrete pavements. Laboratory studies were conducted on field specimens using the flexural fatigue test in the controlled-displacement mode. Tests were performed at 72 deg F and 40 deg F. Tested materials include (1) conventional HMA with AC 2.5 and AC 5; (2) PlusRide RUMAC with AC 5; (3) asphalt-rubber concrete with AC 2.5 (wet Process); and (4) rubberized asphalt-rubber concrete with AC 2.5 (wet/dry process).

Raad, L.; Saboundjian, S.; Yuan, X.

1995-05-01

185

JOINT PERFORMANCE Guide for Optimum  

E-print Network

July 2012 JOINT PERFORMANCE Guide for Optimum of Concrete Pavements #12; #12;Guide for Optimum Joint Performance of Concrete Pavements i Technical Report Documentation Page 1. Report No. 2. Report Date Guide for Optimum Joint Performance of Concrete Pavements July 2012 6. Performing

186

High-performance flexible graphene aptasensor for mercury detection in mussels.  

PubMed

Mercury (Hg) is highly toxic but has been widely used for numerous domestic applications, including thermometers and batteries, for decades, which has led to fatal outcomes due to its accumulation in the human body. Although many types of mercury sensors have been developed to protect the users from Hg, few methodologies exist to analyze Hg(2+) ions in low concentrations in real world samples. Herein, we describe the fabrication and characterization of liquid-ion gated field-effect transistor (FET)-type flexible graphene aptasensor with high sensitivity and selectivity for Hg. The field-induced responses from the graphene aptasensor had excellent sensing performance, and Hg(2+) ions with very low concentration of 10 pM could be detected, which is 2-3 orders of magnitude more sensitive than previously reported mercury sensors using electrochemical systems. Moreover, the aptasensor showed a highly specific response to Hg(2+) ions in mixed solutions. The flexible graphene aptasensor showed a very rapid response, providing a signal in less than 1 s when the Hg(2+) ion concentration was altered. Specificity to Hg(2+) ions was demonstrated in real world samples (in this case samples derived from mussels). The aptasensor was fabricated by transferring chemical vapor deposition (CVD)-grown graphene onto a transparent flexible substrate, and the structure displayed excellent mechanical durability and flexiblility. This graphene-based aptasensor has potential for detecting Hg exposure in human and in the environment. PMID:24279823

An, Ji Hyun; Park, Seon Joo; Kwon, Oh Seok; Bae, Joonwon; Jang, Jyongsik

2013-12-23

187

Porous Pavements in Cold Climates Part 1: Design, Installation, and  

E-print Network

Porous Pavements in Cold Climates Part 1: Design, Installation, and Maintenance A Green-Graded Friction Courses (2002) 3 #12;Part I Overview 1. State of the Practice 2. Common Design and Installation Cold climate performance is strong Winter maintenance has tremendous potential salt reduction Design

188

Measuring Clogging with Pressure Transducers in Permeable Pavement Strips  

EPA Science Inventory

Two issues that have a negative affect on the long term hydrologic performance of permeable pavement systems are surface clogging and clogging at the interface with the underlying soil. Surface clogging limits infiltration capacity and results in bypass if runoff rate exceeds in...

189

Evaluation of a new construction pavement section using the mechanistic-empirical pavement design guide  

NASA Astrophysics Data System (ADS)

The AASHTO Mechanistic-Empirical Design Guide (MEPDG) is one of several "next generation" pavement design approaches intended to address limitations of older empirical methods. This research investigated the capabilities and performance of the MEPDG through analyses of an empirically-designed section of NH Route 16, which the New Hampshire Department of Transportation (NHDOT) indicated may be under-designed. MEPDG distress predictions indicate that the pavement section should achieve a service life of at least 10 years. This was supported by the fatigue analysis of the base course, which also indicated that the pavement may have been damaged by traffic loads prior to the completion of the surface course. During this research, a number of limitations and model behaviors of the MEPDG were observed, some with significant importance to this analysis and to future projects within New Hampshire. Because implementation and full realization of the MEPDG requires significant investment, the results of this research should be considered before undertaking steps towards adoption of the software.

Lowe, Justin

190

Terra Flexible Blanket Solar Array Deployment, On-Orbit Performance and Future Applications  

NASA Technical Reports Server (NTRS)

The Terra spacecraft (formerly identified as EOS AM1) is the flagship in a planned series of NASA/GSFC (Goddard Space Flight Center) Earth observing system satellites designed to provide information on the health of the Earth's land, oceans, air, ice, and life as a total ecological global system. It has been successfully performing its mission since a late-December 1999 launch into a 705 km polar orbit. The spacecraft is powered by a single wing, flexible blanket array using single junction (SJ) gallium arsenide/germanium (GaAs/Ge) solar cells sized to provide five year end-of-life (EOL) power of greater than 5000 watts at 127 volts. It is currently the highest voltage and power operational flexible blanket array with GaAs/Ge cells. This paper briefly describes the wing design as a basis for discussing the operation of the electronics and mechanisms used to achieve successful on-orbit deployment. Its orbital electrical performance to date will be presented and compared to analytical predictions based on ground qualification testing. The paper concludes with a brief section on future applications and performance trends using advanced multi-junction cells and weight-efficient mechanical components.

Kurland, Richard; Schurig, Hans; Rosenfeld, Mark; Herriage, Michael; Gaddy, Edward; Keys, Denney; Faust, Carl; Andiario, William; Kurtz, Michelle; Moyer, Eric; Day, John H. (Technical Monitor)

2000-01-01

191

Terra Flexible Blanket Solar Array Deployment, On-Orbit Performance and Future Applications  

NASA Technical Reports Server (NTRS)

The Terra spacecraft (formerly identified as EOS AM1) is the flagship in a planned series of NASA/GSFC (Goddard Space Flight Center) Earth observing system satellites designed to provide information on the health of the Earth's land, oceans, air, ice, and life as a total ecological global system. It has been successfully performing its mission since a late-December 1999 launch into a 705 km polar orbit. The spacecraft is powered by a single wing, flexible blanket array using single junction (SJ) gallium arsenide/germanium (GaAs/Ge) solar cells sized to provide five year end-of-life (EOL) power of greater than 5000 watts at 127 volts. It is currently the highest voltage and power operational flexible blanket array with GaAs/Ge cells. This paper briefly describes the wing design as a basis for discussing the operation of the electronics and mechanisms used to achieve successful on-orbit deployment. Its orbital electrical performance to date will be presented and compared to analytical predictions based on ground qualification testing. The paper concludes with a brief section on future applications and performance trends using advanced multi-junction cells and weight-efficient mechanical components. A viewgraph presentation is attached that outlines the same information as the paper and includes more images of the Terra Spacecraft and its components.

Kurland, Richard; Schurig, Hans; Rosenfeld, Mark; Herriage, Michael; Gaddy, Edward; Keys, Denney; Faust, Carl; Andiario, William; Kurtz, Michelle; Moyer, Eric; Day, John H. (Technical Monitor)

2000-01-01

192

Crystalline structure effect on the performance of flexible ZnO/polyimide surface acoustic wave devices  

NASA Astrophysics Data System (ADS)

This paper reports the fabrication of flexible surface acoustic wave (SAW) devices on ZnO/polyimide substrates and investigation of the effects of the deposition conditions, crystal quality, and film thickness of the ZnO films on the performance of the SAW devices. The deposition pressure has a significant effect on the crystal quality of the ZnO film, and which in turn affects the transmission of the SAW devices strongly. The device performance improves greatly and is mainly attributed to the better crystal quality of the film deposited at high pressure. The performance of the SAW devices also improves significantly with increase in ZnO film thickness, owing to the reduced defects and improved piezoelectric effect for the films with large grain sizes and better crystallinity as the film thickness increases. Flexible SAW devices with a resonant frequency of 153 MHz, a phase velocity of 1836 m/s, and a coupling coefficient of 0.79% were obtained on the ZnO film of 4 ?m thickness, demonstrated its great potential for applications in electronics and microsystems.

Zhou, Jian; He, Xingli; Jin, Hao; Wang, Wenbo; Feng, Bin; Dong, Shurong; Wang, Demiao; Zou, Guangyi; Luo, J. K.

2013-07-01

193

Fully printed, high performance carbon nanotube thin-film transistors on flexible substrates.  

PubMed

Fully printed transistors are a key component of ubiquitous flexible electronics. In this work, the advantages of an inverse gravure printing technique and the solution processing of semiconductor-enriched single-walled carbon nanotubes (SWNTs) are combined to fabricate fully printed thin-film transistors on mechanically flexible substrates. The fully printed transistors are configured in a top-gate device geometry and utilize silver metal electrodes and an inorganic/organic high-? (~17) gate dielectric. The devices exhibit excellent performance for a fully printed process, with mobility and on/off current ratio of up to ~9 cm(2)/(V s) and 10(5), respectively. Extreme bendability is observed, without measurable change in the electrical performance down to a small radius of curvature of 1 mm. Given the high performance of the transistors, our high-throughput printing process serves as an enabling nanomanufacturing scheme for a wide range of large-area electronic applications based on carbon nanotube networks. PMID:23899052

Lau, Pak Heng; Takei, Kuniharu; Wang, Chuan; Ju, Yeonkyeong; Kim, Junseok; Yu, Zhibin; Takahashi, Toshitake; Cho, Gyoujin; Javey, Ali

2013-08-14

194

Guide Specification for Highway Construction Texturing Concrete Pavement for  

E-print Network

Guide Specification for Highway Construction Texturing Concrete Pavement for Reduced Tire/Pavement Noise using Diamond Grinding Designation: CPSCP GS 1-11 (rev 3/1/2011) National Concrete Pavement for Highway Construction Texturing Concrete Pavement for Reduced Tire/Pavement Noise using Diamond Grinding

195

Pavement Smoothness for Illinois DOT -Doug Dirks 1. Briefly summarize your current pavement smoothness requirements. See below.  

E-print Network

Pavement Smoothness for Illinois DOT - Doug Dirks 1. Briefly summarize your current pavement? N/A Illinois has both standard specifications and a special provision for pavement smoothness-Depth HMA pavements, and PCC Pavements are all included in this special provision. http

196

Pollutant load removal efficiency of pervious pavements: is clogging an issue?  

PubMed

Pervious pavements in car parks and driveways reduce the peak runoff rate and the quantity of runoff discharged into urban drains as well as improve the stormwater quality by trapping the sediments in the infiltrated water. The paper focuses on presenting results from the laboratory tests carried out to evaluate water quality improvements and effects of long-term decrease in infiltration rates with time due to sediments trapping (clogging) within the pavement pores. Clogging was not found to be a major factor affecting pervious pavement performance after simulating 17 years of stormwater quality samples. PMID:19809141

Kadurupokune, N; Jayasuriya, N

2009-01-01

197

Preliminary evaluation of LTPP continuously reinforced concrete (CRC) pavement test sections. Final report, February 1995--October 1998  

SciTech Connect

As part of the study reported here, analysis of data from the LTPP GPS-5 test sections was conducted to identify factors that influence long-term crack spacing in continuously reinforced concrete (CRC) pavements and to determine that effect of crack spacing on pavement performance. Data from the 85 test sections from the GPS-5 experiment were analyzed.

Tayabji, S.D.; Selezneva, O.; Jiang, Y.J.

1999-07-01

198

Flexible Pillared Graphene-Paper Electrodes for High-Performance Electrochemical Supercapacitors  

SciTech Connect

Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s?1, the specific capacitance of the pillared GP is 138 F g^?1 and 83.2 F g^?1 with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s ^?1, the specific capacitance can reach 80 F g^?1 in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. The pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage.

Wang, Gongkai; Sun, Xiang; Lu, Fengyuan; Sun, Hongtao; Yu, Mingpeng; Jiang, Weilin; Liu, Changsheng; Lian, Jie

2012-02-09

199

Pavement Design TTP Orientation Seminar  

E-print Network

­Maintenance ­Rehabilitation ­Reconstruction (Abandonment? Reuse?) · Goal at all stages is greater efficiency, Traffic Considerations, ReDesign 2010-2050 Sustainability Materials ReUse, Vehicle/Pavement Interaction;Traffic Variables Highways - it's the trucks · Loads · Tire pressures · Speeds · Dynamics (interaction

Handy, Susan L.

200

Pavement Design TTP Orientation Seminar  

E-print Network

? Reuse?) · Goal at all stages is greater efficiency ­how is efficiency defined? #12;Where Are We Now Materials ReUse, Vehicle/Pavement Interaction, New Materials, Information Technology Integration #12;Is Variables Highways - it's the trucks · Loads · Tire pressures · Speeds · Dynamics (interaction

Handy, Susan L.

201

Pavement Design TTP Orientation Seminar  

E-print Network

(Abandonment? Reuse?) · Goal at all stages is greater efficiency ­ how is efficiency defined? #12;Where Are We-2050 Sustainability Materials ReUse, Vehicle/Pavement Interaction, New Materials, Information Technology Integration the "good old" days? #12;Traffic Variables Highways - it's the trucks · Loads · Tire pressures · Speeds

Handy, Susan L.

202

Review of permeable pavement systems  

Microsoft Academic Search

The purpose of this review paper is to summarise the wide-range but diffuse literature on predominantly permeable pavement systems (PPS), highlight current trends in research and industry, and to recommend future areas of research and development. The development of PPS as an integral part of sustainable drainage systems is reviewed in the context of traditional and modern urban drainage. Particular

Miklas Scholz; Piotr Grabowiecki

2007-01-01

203

Global warming potential of pavements  

Microsoft Academic Search

Pavements comprise an essential and vast infrastructure system supporting our transportation network, yet their impact on the environment is largely unquantified. Previous life-cycle assessments have only included a limited number of the applicable life-cycle components in their analysis. This research expands the current view to include eight different components: materials extraction and production, transportation, onsite equipment, traffic delay, carbonation, lighting,

Nicholas J. Santero; Arpad Horvath

2009-01-01

204

Ultrafast laser trimming for reduced device leakage in high performance OTFT semiconductors for flexible displays  

NASA Astrophysics Data System (ADS)

Organic semiconductors (OSC) are solution processable synthetic materials with high carrier mobility that promise to revolutionise flexible electronics manufacturing due to their low cost, lightweight and high volume low temperature printing in reel-to-reel (R2R) [1] for applications such as flexible display backplanes (Fig.1), RFID tags, and logic/memory devices. Despite several recent technological advances, organic thin film transistor (OTFT) printing is still not production-ready due to limitations mainly with printing resolution on dimensionally unstable substrates and device leakage that reduces dramatically electrical performance. OTFTs have the source-drain in ohmic contact with the OSC material to lower contact resistance. If they are unpatterned, a leakage pathway from source to drain develops which results in non-optimum on/off currents and not controllable device uniformity (Fig.2). DPSS lasers offer several key advantages for OTFT patterning including maskless, non-contact, dry patterning, scalable large area operation with precision registration, well-suited to R2R manufacturing at overall ?m size resolutions. But the thermal management of laser processing is very important as the devices are very sensitive to heat and thermomechanical damage [2]. This paper discusses 343nm picosecond laser ablation trimming of 50nm thick PTAA, TIPS pentacene and other semiconductor compounds on thin 50nm thick metal gold electrodes in a top gate configuration. It is shown that with careful optimisation, a suitable process window exists resulting in clean laser structuring without damage to the underlying layers while also containing laser debris. Several order of magnitude improvements were recorded in on/off currents up to 106 with OSC mobilities of 1 cm2/Vsec, albeit at slightly higher than optimum threshold voltages which support demanding flexible display backplane applications.

Karnakis, Dimitris; Cooke, Michael D.; Chan, Y. F.; Ogier, Simon D.

2013-03-01

205

Bituminous pavement recycling Aravind K. and Animesh Das  

E-print Network

Bituminous pavement recycling Aravind K. and Animesh Das Department of Civil Engineering IIT Kanpur Introduction The bituminous pavement rehabilitation alternatives are mainly overlaying, recycling and reconstruction. In the recycling process the material from deteriorated pavement, known as reclaimed asphalt

Das, Animesh

206

Pervious Pavement A Strategic Plan For NYC DOT  

E-print Network

Pervious Pavement A Strategic Plan For NYC DOT Presented By: Rene Brana Spring 2012 Capstone: Pervious Pavement - A Strategic Plan for NYC DOT 2 Capstone: Pervious Pavement - A Strategic Plan for NYC DOT 3 Image courtesy of

Qian, Ning

207

High-performance logic circuits using solution-based, low-temperature semiconductors for flexible electronics  

NASA Astrophysics Data System (ADS)

In this work we demonstrate high performance and low-power n-type inverters using solution-based CdS as the semiconductor in thin film transistors. Our fabrication process consists of five mask levels and a maximum temperature of 150 °C. The CdS is deposited using chemical bath deposition at 70 °C to provide full compatibility with flexible substrates. Isolated TFTs showed mobilities up to 10 cm2/V-s and threshold voltages of approximately 0.5V. Inverters were biased at 1, 3 and 5 V, resulting in maximum gains in the range of 60 at VDD = 3V. The devices and circuits are fully patterned using standard photolithographic techniques that can be used to design more complex circuitry for flexible and large area electronic applications. In addition we used an extraction parameter method for our TFTs that allows the use of regular SPICE simulation software to design and test the circuits. Our simulations are in good agreement with the experimental data for isolated devices and inverters. Other circuits such as NAND gates are also demonstrated.

Mejia, Israel; Salas-Villasenor, Ana L.; Murphy, John W.; Kunnen, George R.; Cantley, Kurtis D.; Allee, David R.; Gnade, Bruce E.; Quevedo-Lopez, Manuel A.

2013-05-01

208

Investigation and application of fractured slab techniques for PCC pavements. Final report, May 1996--April 1999  

SciTech Connect

Slab fracture techniques, including break and seat, crack and seat, and rubblization have in recent years gained widespread recognition among pavement engineers as means for eliminating or substantially reducing the potential for reflective cracking in hot mix asphalt (HMA) overlays over portland cement concrete (PCC) pavements. Guidelines for the use of these techniques in Wisconsin, however, have not been clearly established. This reports examines the PCC rehabilitation techniques of rubblization and crack and seat used in Wisconsin and their performance. The report examines the literature and evaluates the critical issues associated with the use of PCC fracture techniques by various agencies. Several elements pertinent to fracture techniques are also identified and incorporated in a database for in-service fractured overlaid PCC pavements in Wisconsin. In addition, the in-service performance of cracked and seated and rubblized pavements in Wisconsin is evaluated.

Owusu-Ababio, S.; Nelson, T.

1999-04-01

209

High performance low temperature carbon composite catalysts for flexible dye sensitized solar cells.  

PubMed

Roll-to-roll manufacturing of dye sensitized solar cells (DSSCs) requires efficient and low cost materials that adhere well on the flexible substrates used. In this regard, different low temperature carbon composite counter electrode (CE) catalyst ink formulations for flexible DSSCs were developed that can be simply and quickly coated on plastic substrates and dried below 150 °C. The CEs were investigated in terms of photovoltaic performance in DSSCs by current-voltage measurements, mechanical adhesion properties by bending and tape tests, electro-catalytic performance by electrochemical impedance spectroscopy and microstructure by electron microscopy. In the bending and tape tests, PEDOT-carbon composite catalyst layers exhibited higher elasticity and better adhesion on all the studied substrates (ITO-PET and ITO-PEN plastic, and FTO-glass), compared to a binder free carbon composite and a TiO2 binder enriched carbon composite, and showed lower charge transfer resistance (1.5-3 ? cm(2)) than the traditional thermally platinized CE (5 ? cm(2)), demonstrating better catalytic performance for the tri-iodide reduction reaction. Also the TiO2 binder enriched carbon composite showed good catalytic characteristics and relatively good adhesion on ITO-PET, but on ITO-PEN its adhesion was poor. A DSSC with the TiO2 binder enriched catalyst layer reached 85% of the solar energy conversion efficiency of the reference DSSC based on the traditional thermally platinized CE. Based on the aforementioned characteristics, these carbon composites are promising candidates for replacing the platinum catalyst in a high volume roll-to-roll manufacturing process of DSSCs. PMID:24042582

Hashmi, Syed Ghufran; Halme, Janne; Saukkonen, Tapio; Rautama, Eeva-Leena; Lund, Peter

2013-10-28

210

Final Technical Report, Oct 2004 - Nov. 2006, High Performance Flexible Reversible Solid Oxide Fuel Cell  

SciTech Connect

This report summarizes the work performed for the program entitled “High Performance Flexible Reversible Solid Oxide Fuel Cell” under Cooperative Agreement DE-FC36-04GO14351 for the U. S. Department of Energy. The overall objective of this project is to demonstrate a single modular stack that generates electricity from a variety of fuels (hydrogen and other fuels such as biomass, distributed natural gas, etc.) and when operated in the reverse mode, produces hydrogen from steam. This project has evaluated and selected baseline cell materials, developed a set of materials for oxygen and hydrogen electrodes, and optimized electrode microstructures for reversible solid oxide fuel cells (RSOFCs); and demonstrated the feasibility and operation of a RSOFC multi-cell stack. A 10-cell reversible SOFC stack was operated over 1000 hours alternating between fuel cell (with hydrogen and methane as fuel) and steam electrolysis modes. The stack ran very successfully with high power density of 480 mW/cm2 at 0.7V and 80% fuel utilization in fuel cell mode and >6 SLPM hydrogen production in steam electrolysis mode using about 1.1 kW electrical power. The hydrogen generation is equivalent to a specific capability of 2.59 Nm3/m2 with electrical energy demand of 3 kWh/Nm3. The performance stability in electrolysis mode was improved vastly during the program with a degradation rate reduction from 8000 to 200 mohm-cm2/1000 hrs. This was accomplished by increasing the activity and improving microstructure of the oxygen electrode. Both cost estimate and technology assessment were conducted. Besides the flexibility running under both fuel cell mode and electrolysis mode, the reversible SOFC system has the potentials for low cost and high efficient hydrogen production through steam electrolysis. The cost for hydrogen production at large scale was estimated at ~$2.7/kg H2, comparing favorably with other electrolysis techology.

Guan, Jie; Minh, Nguyen

2007-02-21

211

Research on Performance Prediction and Maintenance Strategy of Expressway Based on Fuzzy Optimum Theory  

Microsoft Academic Search

Pavement Preventive Maintenance (PPM)technologies is adopted to predict the performance of pavement and select effective strategies on the expressway, the method can enormously extends the service life of pavement and result in lower maintenance costs. This paper describes prediction of highway pavement performance by means of gray system theory, and the gradual solution, which leads to the optimal model, is

Liu Lijun; Zhang Hui

2010-01-01

212

Can we build a truly high performance computer which is flexible and transparent?  

PubMed

State-of-the art computers need high performance transistors, which consume ultra-low power resulting in longer battery lifetime. Billions of transistors are integrated neatly using matured silicon fabrication process to maintain the performance per cost advantage. In that context, low-cost mono-crystalline bulk silicon (100) based high performance transistors are considered as the heart of today's computers. One limitation is silicon's rigidity and brittleness. Here we show a generic batch process to convert high performance silicon electronics into flexible and semi-transparent one while retaining its performance, process compatibility, integration density and cost. We demonstrate high-k/metal gate stack based p-type metal oxide semiconductor field effect transistors on 4 inch silicon fabric released from bulk silicon (100) wafers with sub-threshold swing of 80 mV dec(-1) and on/off ratio of near 10(4) within 10% device uniformity with a minimum bending radius of 5 mm and an average transmittance of ~7% in the visible spectrum. PMID:24018904

Rojas, Jhonathan P; Torres Sevilla, Galo A; Hussain, Muhammad M

2013-01-01

213

Investigation of mechanical properties of pavement through electromagnetic techniques  

NASA Astrophysics Data System (ADS)

Ground-penetrating radar (GPR) is considered as one of the most flexible geophysical tools that can be effectively and efficiently used in many different applications. In the field of pavement engineering, GPR can cover a wide range of uses, spanning from physical to geometrical inspections of pavements. Traditionally, such inferred information are integrated with mechanical measurements from other traditional (e.g. plate bearing test) or non-destructive (e.g. falling weight deflectometer) techniques, thereby resulting, respectively, in time-consuming and low-significant measurements, or in a high use of technological resources. In this regard, the new challenge of retrieving mechanical properties of road pavements and materials from electromagnetic measurements could represent a further step towards a greater saving of economic resources. As far as concerns unpaved and bound layers it is well-known that strength and deformation properties are mostly affected, respectively, by inter-particle friction and cohesion of soil particles and aggregates, and by bitumen adhesion, whose variability is expressed by the Young modulus of elasticity. In that respect, by assuming a relationship between electromagnetic response (e.g. signal amplitudes) and bulk density of materials, a reasonable correlation between mechanical and electric properties of substructure is therefore expected. In such framework, a pulse GPR system with ground-coupled antennae, 600 MHz and 1600 MHz centre frequencies was used over a 4-m×30-m test site composed by a flexible pavement structure. The horizontal sampling resolution amounted to 2.4×10-2 m. A square regular grid mesh of 836 nodes with a 0.40-m spacing between the GPR acquisition tracks was surveyed. Accordingly, a light falling weight deflectometer (LFWD) was used for measuring the elastic modulus of pavement at each node. The setup of such instrument consisted of a 10-kg falling mass and a 100-mm loading plate so that the influence domain of the elasticity measure could be comparable to that of the radar signal. Good agreement were found between high Young modulus values and repaved zones, whereas damaged areas were characterized by lower values of E. Tomographic maps of amplitudes along the z axis were extracted up to a depth of z

Benedetto, Andrea; Tosti, Fabio; D'Amico, Fabrizio

2014-05-01

214

Removable Urban Pavements: An innovative, sustainable technology Journal: International Journal of Pavement Engineering  

E-print Network

1 Removable Urban Pavements: An innovative, sustainable technology Journal: International Journal of Pavement Engineering URL: http://mc.manuscriptcentral.com/gpav E-mail: IJPE.editor@citg.tudelft.nl, alqadi@uiuc.edu Removable Urban Pavements: An innovative, sustainable technology François de Larrard1, Thierry Sedran2, Jean

Paris-Sud XI, Université de

215

Comparative field permeability measurement of permeable pavements using ASTM C1701 and NCAT permeameter methods.  

PubMed

Fully permeable pavement is gradually gaining support as an alternative best management practice (BMP) for stormwater runoff management. As the use of these pavements increases, a definitive test method is needed to measure hydraulic performance and to evaluate clogging, both for performance studies and for assessment of permeability for construction quality assurance and maintenance needs assessment. Two of the most commonly used permeability measurement tests for porous asphalt and pervious concrete are the National Center for Asphalt Technology (NCAT) permeameter and ASTM C1701, respectively. This study was undertaken to compare measured values for both methods in the field on a variety of permeable pavements used in current practice. The field measurements were performed using six experimental section designs with different permeable pavement surface types including pervious concrete, porous asphalt and permeable interlocking concrete pavers. Multiple measurements were performed at five locations on each pavement test section. The results showed that: (i) silicone gel is a superior sealing material to prevent water leakage compared with conventional plumbing putty; (ii) both methods (NCAT and ASTM) can effectively be used to measure the permeability of all pavement types and the surface material type will not impact the measurement precision; (iii) the permeability values measured with the ASTM method were 50-90% (75% on average) lower than those measured with the NCAT method; (iv) the larger permeameter cylinder diameter used in the ASTM method improved the reliability and reduced the variability of the measured permeability. PMID:23434738

Li, Hui; Kayhanian, Masoud; Harvey, John T

2013-03-30

216

Incorporating Risk and Uncertainty into Pavement Network Maintenance and Rehabilitation Budget Allocation Decisions  

E-print Network

, pavement noise, and surface friction (Johnson 2000). Short-term M&R effectiveness can be measured in terms of the reduction of deterioration, and performance improvement jump (Labi and Sinha 2003). For a long-term analysis, the cost... data, costs can be estimated using engineering judgments, standard unit costs, or even correlations with pavement condition and characteristics (Juni et al. 2008; Sinha et al. 2005). Perrone et al. (Perrone et al. 1998) point out that no matter which...

Menendez Acurio, Jose Rafael

2014-07-30

217

Influence of landing gear flexibility on aircraft performance during ground roll  

NASA Technical Reports Server (NTRS)

An analysis is made of the influence of landing gear deflection characteristics on aircraft performance on the ground up to rotation. A quasi-steady dynamic equilibrium state is assumed, including other simplifying assumptions such as calm air conditions and normal aircraft lift and drag. Ground incidence is defined as the angle made by the mean aerodynamic chord of the wing with respect to the ground plane, and equations are given for force and balance which determine the quasi-equilibrium conditions for the aircraft during ground roll. Results indicate that the landing gear deflections lead to a substantial increase in the angle of attack, and the variation in the ground incidence due to landing gear flexibility could be as much as + or - 50%, and the reduction in tail load requirements almost 25%.

Sivaramakrishnan, M. M.

1981-01-01

218

Defect analysis and mechanical performance of plasma-deposited thin films on flexible polycarbonate substrates  

NASA Astrophysics Data System (ADS)

A simple solvent-etch based technique is developed to visualize and quantify defects in transparent thin films deposited on flexible polymer substrates. This approach is used to characterize defects in as-deposited films and to monitor their evolution as a function of applied and repetitive bending. Thin films investigated include sputtered indium tin oxide (ITO) and alumina-silicone nanolaminates fabricated by plasma-enhanced chemical vapor deposition. It is shown that the use of nanolaminate architectures reduces the defect density by two orders of magnitude relative to a single alumina layer. The pinhole density increases when nanolaminates are subjected to applied stress, and at a critical density of ˜10/mm2 the isolated defects coalesce into macroscopic cracks. In the case of ITO an optimum film thickness is identified that balances electronic performance with mechanical integrity. Conductivity correlates with defect density, and the films displayed very similar performance under tensile and compressive strain. A critical radius of curvature of 0.75 in. was identified, but films cycled below the threshold strain demonstrated robust performance, with only negligible changes in resistivity through 2000 bending cycles. The strong performance under strain is attributed to the amorphous nature of the sputtered ITO.

Patel, Rakhi P.; Wolden, Colin A.

2013-03-01

219

Recycling of water-susceptible pavements  

NASA Astrophysics Data System (ADS)

Several bituminous concrete interstate pavements that experienced failures suspected to have been caused by stripping were investigated. On two projects, the degree of deterioration, potential serviceability, and possible remedial measures were studied. Cores were taken to determine the degreee of stripping and tensile strength, and dynaflect tests were performed. An emulsion mix design was developed for stripped bituminous concrete removed from another project with the expectation that it could be used as a surface mix on a highway with a low traffic volume. While this expectation was not realized, it was concluded that the material is suitable for use in a base mix. A maintenance resurfacing on a fourth project that experienced stripping failure is being monitored and the performance is being evaluated.

Maupin, G. W.

1980-05-01

220

Reinforcement of asphalt concrete pavement by segments of exhausted fiber used for sorption of oil spill  

NASA Astrophysics Data System (ADS)

The paper is aimed at construction of the experimental road pavement made of dispersed reinforced asphalt concrete. Electronic paramagnetic resonance, infrared spectroscopy and fluorescent bitumen studies were used to prove that disperse reinforcement of asphalt concrete mixtures with fibers of exhausted sorbents reduce the selective filtration of low polymeric fractions of petroleum bitumen and improve its properties in the adsorption layer. Sesquioxides are neutralized as catalysts aging asphalt binder. This leads to improvement in the elasticity of bitumen films at low temperatures and provide better crack resistance of coatings to reduce the intensity of the aging of asphalt binder, and, therefore, to increase the durability of road pavements. The experimental road pavement made of dispersed reinforced asphalt concrete operated during 4 years and demonstrated better transport- performance properties in comparison with the analogue pavements.

Lukashevich, V. N.; Efanov, I. N.

2015-01-01

221

Enhanced Thermoelectric Performance of PEDOT:PSS Flexible Bulky Papers by Treatment with Secondary Dopants.  

PubMed

For inorganic thermoelectric materials, Seebeck coefficient and electrical conductivity are interdependent, and hence optimization of thermoelectric performance is challenging. In this work we show that thermoelectric performance of PEDOT:PSS can be enhanced by greatly improving its electrical conductivity in contrast to inorganic thermoelectric materials. Free-standing flexible and smooth PEDOT:PSS bulky papers were prepared using vacuum-assisted filtration. The electrical conductivity was enhanced to 640, 800, 1300, and 1900 S cm(-1) by treating PEDOT:PSS with ethylene glycol, polyethylene glycol, methanol, and formic acid, respectively. The Seebeck coefficient did not show significant variation with the tremendous conductivity enhancement being 21.4 and 20.6 ?V K(-1) for ethylene glycol- and formic acid-treated papers, respectively. This is because secondary dopants, which increase electrical conductivity, do not change oxidation level of PEDOT. A maximum power factor of 80.6 ?W m(-1) K(-2) was shown for formic acid-treated samples, while it was only 29.3 ?W m(-1) K(-2) for ethylene glycol treatment. Coupled with intrinsically low thermal conductivity of PEDOT:PSS, ZT ? 0.32 was measured at room temperature using Harman method. We investigated the reasons behind the greatly enhanced thermoelectric performance. PMID:25475257

Mengistie, Desalegn A; Chen, Chang-Hsiao; Boopathi, Karunakara M; Pranoto, Ferry W; Li, Lain-Jong; Chu, Chih-Wei

2015-01-14

222

Preliminary evaluation of the lifecycle costs and market barriers of reflective pavements  

SciTech Connect

The objective of this study is to evaluate the life cycle costs and market barriers associated with using reflective paving materials in streets and parking lots as a way to reduce the urban heat island effect. We calculated and compared the life cycle costs of conventional asphalt concrete (AC) pavements to those of other existing pavement technologies with higher reflectivity-portland cement concrete (PCC), porous pavements, resin pavements, AC pavements using light-colored chip seals, and AC pavements using light-colored asphalt emulsion additives. We found that for streets and parking lots, PCC can provide a cost-effective alternative to conventional AC when severely damaged pavements must be completely reconstructed. We also found that rehabilitating damaged AC streets and intersections with thin overlays of PCC (ultra-thin white topping) can often provide a cost-effective alternative to standard rehabilitation techniques using conventional AC. Chip sealing is a common maintenance treatment for low-volume streets which, when applied using light-colored chips, could provide a reflective pavement surface. If the incremental cost of using light-colored chips is low, this chip sealing method could also be cost-effective, but the incremental costs of light-colored chips are as of yet uncertain and expected to vary. Porous pavements were found to have higher life cycle costs than conventional AC in parking lots, but several cost-saving features of porous pavements fell outside the boundaries of this study. Resin pavements were found to be only slightly more expensive than conventional AC, but the uncertainties in the cost and performance data were large. The use of light-colored additives in asphalt emulsion seal coats for parking lot pavements was found to be significantly more expensive than conventional AC, reflecting its current niche market of decorative applications. We also proposed two additional approaches to increasing the reflectivity of conventional AC, which we call the chipping and aggregate methods, and calculated their potential life cycle costs. By analyzing the potential for increased pavement durability resulting from these conceptual approaches, we then estimated the incremental costs that would allow them to be cost-effective compared to conventional AC. For our example case of Los Angeles, we found that those allowable incremental costs range from less than dollar 1 to more than dollar 11 per square yard (dollar 1 to dollar 13 per square meter) depending on street type and the condition of the original pavement. Finally, we evaluated the main actors in the pavement market and the existing and potential market barriers associated with reflective pavements. Apart from situations where lifecycle costs are high compared to conventional AC, all reflective paving technologies face a cultural barrier based on the belief that black is better. For PCC, high first costs were found to be the most significant economic barrier, particularly where agencies are cons trained by first cost. Lack of developer standards was found to be a significant institutional barrier to PCC since developers are often not held accountable for the long-term maintenance of roads after initial construction, which creates a misplaced incentive to build low first-cost pavements. PCC also faces site-specific barriers such as poorly compacted base soils and proximity to areas of frequent utility cutting.

Ting, M.; Koomey, J.G.; Pomerantz, M.

2001-11-21

223

A test of porous pavement effectiveness on clay soils during natural storm events.  

PubMed

Porous pavements allow precipitation to infiltrate through the pavement to the soil, reducing the volume of stormwater runoff produced at a site. However, porous pavements are not widely used on fine-grained soils due to concerns about their performance. Our objective was to investigate the efficacy of porous pavements in controlling stormwater runoff on clay soils. We compared the performance of an asphalt parking lot and a porous pavement parking lot of grass pavers in Athens, Georgia, USA, over relatively small and low-intensity rain events. The porous lot produced 93% less runoff than the asphalt lot. The total volume of runoff at the porous lot was significantly less than the asphalt lot (t = 2.96, p = 0.009). Turbidity was significantly greater at the asphalt lot (t = 6.18, p < 0.001) whereas conductivity was significantly higher at the porous lot (t = 2.31, p = 0.03). Metal and nutrient concentrations were below detection limits at both lots during seven of nine small storm events. During events in which we could detect pollutants, calcium, zinc, silica, and total phosphorus concentrations were higher at the asphalt lot whereas total nitrogen concentrations were greater at the porous lot. Our results suggest porous pavements are a viable option for reducing stormwater runoff and some pollutants from small storms or the first flush from large storms on clay soils. PMID:16426659

Dreelin, Erin A; Fowler, Laurie; Ronald Carroll, C

2006-02-01

224

Statistical classification of road pavements using near field vehicle rolling noise measurements.  

PubMed

Low noise surfaces have been increasingly considered as a viable and cost-effective alternative to acoustical barriers. However, road planners and administrators frequently lack information on the correlation between the type of road surface and the resulting noise emission profile. To address this problem, a method to identify and classify different types of road pavements was developed, whereby near field road noise is analyzed using statistical learning methods. The vehicle rolling sound signal near the tires and close to the road surface was acquired by two microphones in a special arrangement which implements the Close-Proximity method. A set of features, characterizing the properties of the road pavement, was extracted from the corresponding sound profiles. A feature selection method was used to automatically select those that are most relevant in predicting the type of pavement, while reducing the computational cost. A set of different types of road pavement segments were tested and the performance of the classifier was evaluated. Results of pavement classification performed during a road journey are presented on a map, together with geographical data. This procedure leads to a considerable improvement in the quality of road pavement noise data, thereby increasing the accuracy of road traffic noise prediction models. PMID:20968348

Paulo, Joel Preto; Coelho, J L Bento; Figueiredo, Mário A T

2010-10-01

225

Anionic polymer electrolyte with enhanced electrochemical performance based on surface-charged latex nanoparticles for flexible lithium-ion batteries  

NASA Astrophysics Data System (ADS)

In the present paper, an anionic polymer electrolyte (APE) is facilely prepared using the surface-charged latex nanoparticles as the building blocks for the flexible lithium-ion batteries. Driven by the self-assembly of surface-charged latex, the APE demonstrates nanoporous structure, which provides continuous pathway for lithium conduction. The anionic polymer membrane exhibits mechanical flexibility before and after swollen with liquid electrolyte. Performance benefits of the anionic polymer membrane, as compared to commercialized polyethylene (PE) separator, are elucidated in terms of thermal shrinkage, liquid electrolyte wettability, mechanical bendability and open circuit voltage (OCV). Based on comprehensive characterization of the anionic polymer membrane/electrolyte characteristics, feasibility of applying the APE to electrolytes for flexible lithium-ion batteries is explored. The well-developed ion-conductive channel of the APE, in conjunction with stability of the surface-charged nanoparticles during cycling, plays a crucial role in providing excellent in cell performance.

Ma, Xianguo; Huang, Xinglan; Gao, Jiandong; Zhang, Shu; Peng, Zuling; Deng, Zhenghua; Suo, Jishuan

2014-12-01

226

Highway pavement distress evaluation: Modeling measurement error  

Microsoft Academic Search

There has been a proliferation of inspection technologies to quantify distresses on highway pavement systems. These technologies employ varying measurement principles and are subject to measurement errors. Estimates of measurement errors are therefore required in order to select among these techniques, and to get accurate assessments of pavement condition. There is abundant literature concerning techniques available for the numerical study

Frannie Humplick

1992-01-01

227

Fractionation of heavy metals in pavement runoff  

Microsoft Academic Search

Abstract The transport of anthropogenic constituents by runoff from urban roadways can adversely impact the quality of adjacent receiving waters and soils. Metal elements are the most,persistent constituents found in pavement,runoff. A section of urban highway pavement in Cincinnati, Ohio, USA with an average daily traffic count of 150 000 vehicles was instrumented to sample lateral sheet flow from the

John J. Sansalone; Steven G. Buchberger; Souhail R. Al-abed

1996-01-01

228

Pervious Pavement System Evaluation-Paper  

EPA Science Inventory

The use of a pervious pavement can be effective as a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete paver systems as a type of porous pavement. Although the pavers are impermeable, the spaces between the pave...

229

SORPTIVITY-BASED SERVICE LIFE PREDICTIONS FOR CONCRETE PAVEMENTS  

E-print Network

SORPTIVITY-BASED SERVICE LIFE PREDICTIONS FOR CONCRETE PAVEMENTS by Dale P. Bentz, Mark A. Ehlen Pavements. Proceedings, Volume 1. International Society for Concrete Pavements. September 9-13, 2001 Pavements ­ Orlando, Florida, USA ­ September 9-13, 2001. 181 SORPTIVITY-BASED SERVICE LIFE PREDICTIONS

Bentz, Dale P.

230

RESEARCH Open Access Pavement crack characteristic detection based  

E-print Network

RESEARCH Open Access Pavement crack characteristic detection based on sparse representation Xiaoming Sun1 , Jianping Huang1 , Wanyu Liu1* and Mantao Xu2 Abstract Pavement crack detection plays an important role in pavement maintaining and management. The three- dimensional (3D) pavement crack detection

Joensuu, University of

231

CHECKLIST FOR INSPECTION OF POROUS PAVEMENTS Location: Inspector  

E-print Network

CHECKLIST FOR INSPECTION OF POROUS PAVEMENTS Location: Inspector: Date: Time: Site Conditions: Date minimum, Spring & Fall) Clean porous pavement to remove sediment and organic debris on the pavement surface via vacuum street sweeper. S U Adjacent non porous pavement vacuumed S U Clean catch basins (if

232

New Developments in the Debate on Pavement-Vehicle  

E-print Network

New Developments in the Debate on Pavement-Vehicle Interaction: The Impact of Pavement Design aerodynamics Improve energy efficiency Reduce rolling resistance, including pavement-vehicle interaction #12 standards for big trucks" February 18, 2014 What about fuel efficiency standards for pavements? #12;Slide 5

de Weck, Olivier L.

233

TEXAS PAVEMENT PRESERVATION CENTER FOUR-YEAR SUMMARY REPORT  

E-print Network

TEXAS PAVEMENT PRESERVATION CENTER FOUR-YEAR SUMMARY REPORT Dr. Yetkin Yildirim, P.E., TPPC Director E-mail: yetkin@mail.utexas.edu Mailing address: Texas Pavement Preservation Center Center................................................................................................ 100 #12;#12;TEXAS PAVEMENT PRESERVATION CENTER (TPPC) About the Center The Texas Pavement Preservation

Texas at Austin, University of

234

Recycling asphalt pavements. January 1975-January 1990 (a Bibliography from the COMPENDEX data base). Report for January 1975-January 1990  

SciTech Connect

This bibliography contains citations concerning the recycling of asphalt-containing pavement materials. Articles include examples of recycling asphalt pavements; performance testing of recycled paving; methods including cold in-place, cold off-site, and hot-mix recycling; additives in recycled pavement for better performance; use of scrap roofing asphalt in conjunction with recycled paving; economics of recycling; process design; and process variables. Recycling of other materials is considered in related bibliographies. (Contains 130 citations fully indexed and including a title list.)

Not Available

1990-03-01

235

Greenhouse gas emissions of alternative pavement designs: framework development and illustrative application.  

PubMed

Pavement rehabilitation is carbon intensive and the choice of pavement type is a critical factor in controlling greenhouse gas (GHG) emissions. The existing body of knowledge is not able to support decision-making on pavement choice due to a lack of consensus on the system boundaries, the functional units and the estimation periods. Excessive data requirements further inhibit the generalization of the existing methodologies for design evaluation at the early planning stage. This study proposes a practical life-cycle GHG estimation approach, which is arguably effective to benchmark pavement emissions given project bid tabulation. A set of case studies conducted for this study suggest that recycled asphalt pavement (e.g., foam stabilized base (FSB), and warm mix asphalt (WMA)) would prevent up to 50% of GHGs from the initial construction phase. However, from a life-cycle perspective, pavement emissions are dictated largely by the traffic characteristics and the analysis period for the use phase. The benefits from using recycled materials (e.g., FSB) are likely to diminish if the recycled products do not perform as well as those properly proportioned with less recycled materials, or if the recycled materials are locally unavailable. When the AADT reaches 10,000, use phase releases more than 97% of the life cycle emissions and the emissions difference among alternative designs will be within 1%. PMID:24333742

Liu, Xiaoyu; Cui, Qingbin; Schwartz, Charles

2014-01-01

236

An economic based decision support system for project level pavement type selection  

NASA Astrophysics Data System (ADS)

This dissertation describes a project-level pavement type selection procedure developed for use in roadway agencies and details the overall decision framework required for making dependable pavement type selection decisions. The developed pavement type selection procedure will enable TxDOT to meet the FHWA policy guidelines, and will enable TxDOT engineers to make rational decisions that maximize benefits from expenditure of taxpayers' dollars. Salient results from the national and Texas level questionnaire surveys regarding their pavement type selection practices are documented. Three important factors: agency costs, user delay costs, and performance levels associated with candidate strategies are thoroughly evaluated and quantified for economic comparisons. Economic evaluations are primarily based on the life cycle cost analysis (LCCA) and the cost-effectiveness analysis. It also describes the requirements for and approach to generating candidate pavement strategies. The impact of miscellaneous factors on pavement type selection is also discussed. Some guidelines are suggested for the final strategy selection. A computer program TxPTS is developed to automate the economic evaluation procedures developed in this study. Finally, a few example case studies are conducted to demonstrate the use of the TxPTS computer program and to represent the economic sensitivity of candidate strategies.

Beg, Muhammad Arif

237

Biofuel production system with operation flexibility: Evaluation of economic and environmental performance under external disturbance  

NASA Astrophysics Data System (ADS)

Biomass derived liquid hydrocarbon fuel (biofuel) has been accepted as an effective way to mitigate the reliance on petroleum and reduce the greenhouse gas emissions. An increasing demand for second generation biofuels, produced from ligno-cellulosic feedstock and compatible with current infrastructure and vehicle technologies, addresses two major challenges faced by the current US transportation sector: energy security and global warming. However, biofuel production is subject to internal disturbances (feedstock supply and commodity market) and external factors (energy market). The biofuel industry has also heavily relied on government subsidy during the early development stages. In this dissertation, I investigate how to improve the economic and environmental performance of biorefineries (and biofuel plant), as well as enhance its survivability under the external disturbances. Three types of disturbance are considered: (1) energy market fluctuation, (2) subsidy policy uncertainty, and (3) extreme weather conditions. All three factors are basically volatile, dynamic, and even unpredictable, which makes them difficult to model and have been largely ignored to date. Instead, biofuel industry and biofuel research are intensively focused on improving feedstock conversion efficiency and capital cost efficiency while assuming these advancements alone will successfully generate higher profit and thus foster the biofuel industry. The collapse of the largest corn ethanol biofuel company, Verasun Energy, in 2008 calls into question this efficiency-driven approach. A detailed analysis has revealed that although the corn ethanol plants operated by Verasun adopted the more efficient (i.e. higher ethanol yield per bushel of corn and lower capital cost) dry-mill technology, they could not maintain a fair profit margin under fluctuating market condition which made ethanol production unprofitable. This is because dry-mill plant converts a single type of biomass feedstock (corn grain) into a single primary product (ethanol). The traditional lower efficient (i.e. lower ethanol yield per bushel of corn and higher capital cost) wet-mill plant has a more diverse and adjustable product portfolio i.e. corn syrup, starch, and ethanol. The fact that only the dry-mill corn ethanol plants have bankrupted while the wet-mill corn ethanol plants have survived the late 2000s economy recession suggests that the higher conversion efficiency achieved by the dry-mill production mode has jeopardized operational flexibility, a design operational feature I agree that is indispensable for the biofuel plant's long term profit and viability. Based on the analysis of corn ethanol production, operational flexibility has been proposed as a key strategy for the next generation biofuel plants to improve its lifetime economic performance, as well as to enhance its survivability under external disturbances. This strategy requires the biofuel plant to adopt a flexible feedstock management, making it possible to utilize alternative types of biomass feedstock when the primary feedstock supply is disturbed. Biofuel plants also need to produce a wider range of final products that could meet the preference variation that either comes from the energy market or from the subsidy policy. Aspen Plus model based numerical simulations have been carried out for a thermochemical ethanol plant and a Fischer Tropsch plant (both are assumed to be located in southwest Indiana) to test this strategy under the external disturbances of extreme weather impact, different energy price projections and various subsidy policy combinations. For the thermochemical ethanol plant, effects of extreme weather conditions are mainly evaluated. It has been shown that this strategy could effectively increase the net present value of the biofuel plant and significantly decrease the GHG emission comparing with the traditional single-feedstock strategy, when the extreme weather conditions are considered. It has also been demonstrated that this strategy could significantly decrease the possibility for the bio

Kou, Nannan

238

Road Materials and Pavements Design. Volume X No X/2009, pages 1 to 16 Pavement Design for Curved Road Sections  

E-print Network

Road Materials and Pavements Design. Volume X ­ No X/2009, pages 1 to 16 Pavement Design for Curved pavements Christophe Petit* -- Malick Diakhaté* -- Anne Millien* -- Annabelle Phelipot-Mardelé* -- Bertrand@eurovia.com ABSTRACT. This paper focuses on damage processes other than the main one observed and studied in pavement

Paris-Sud XI, Université de

239

An analysis of pavement heat flux to optimize the1 water efficiency of a pavement-watering method2  

E-print Network

An analysis of pavement heat flux to optimize the1 water efficiency of a pavement-watering method2.hendel@paris.fr)8 9 Preprint version. Uploaded on May 12th , 2014.10 Abstract: Pavement-watering as a technique rarely been conducted. We propose an15 analysis of pavement heat flux at a depth of 5 cm and solar

Paris-Sud XI, Université de

240

Improved performance of flexible amorphous silicon solar cells with silver nanowires  

NASA Astrophysics Data System (ADS)

A novel hybrid electrode structure using Ag nanowires (NWs) to create surface plasmons to enhance light trapping is designed and applied on the front surface of hydrogenated amorphous silicon (a-Si:H) solar cells on steel substrates, targeting broad-band absorption enhancements. Ag NWs were synthesized using a soft and self-seeding process. The produced Ag NWs were deposited on indium tin oxide (ITO) glass substrates or the ITO layers of the as-prepared flexible a-Si:H solar cells to form Ag NW-ITO hybrid electrodes. The Ag NW-ITO hybrid electrodes were optimized to achieve maximum optical enhancement using surface plasmons and obtain good electrical contacts in cells. Finite-element electromagnetic simulations confirmed that the presence of the Ag NWs resulted in increased electromagnetic fields within the a-Si:H layer. Compared to the cell with conventional ITO electrode, the measured quantum efficiency of the best performing a-Si:H cell shows an obvious enhancement in the wavelength range from 330 nm to 600 nm. The cell based on the optimized Ag NW-ITO demonstrates an increase about 4% in short-circuit current density and over 6% in power conversion efficiency under AM 1.5 illumination.

Chen, Y. R.; Li, Z. Q.; Chen, X. H.; Liu, C.; Ye, X. J.; Wang, Z. B.; Sun, Z.; Huang, S. M.

2012-12-01

241

A biodegradable gel electrolyte for use in high-performance flexible supercapacitors.  

PubMed

Despite the significant advances in solid polymer electrolytes used for supercapacitors, intractable problems including poor ionic conductivity and low electrochemical performance limit the practical applications. Herein, we report a facile approach to synthesize a NaCl-agarose gel electrolyte for use in flexible supercapacitors. The as-prepared agarose hydrogel consists of a three-dimensional chemically interconnected agarose backbone and oriented interparticular submicropores filled with water. The interconnected agarose matrix acts as a framework that provides mechanical stability to the gel electrolyte and hierarchical porous networks for optimized ion transport. The developed pores with the water filler provide an efficient ionic pathway to the storage sites of electrode. With these properties, the gel electrolyte enables the supercapacitor to have a high specific capacitance of 286.9 F g(-1) and a high rate capability that is 80% of specific capacitance obtained in the case of a liquid electrolyte at 100 mV s(-1). In addition, attributed to the simple procedure and its components, the gel electrolyte is highly scalable, cost-effective, safe, and nontoxic. Thus, the developed gel electrolyte has the potential for use in various energy storage and delivery systems. PMID:25622040

Moon, Won Gyun; Kim, Gil-Pyo; Lee, Minzae; Song, Hyeon Don; Yi, Jongheop

2015-02-18

242

Microporous Ni??(HPO?)?(OH)? nanocrystals for high-performance flexible asymmetric all solid-state supercapacitors.  

PubMed

Microporous nickel phosphite [Ni11(HPO3)8(OH)6] nanocrystals were prepared using a hydrothermal method, and were successfully applied as a positive electrode in a flexible all solid-state asymmetric supercapacitor. Because of the specific micro/nanostructure, the flexible solid-state asymmetric supercapacitor can achieve a maximum energy density of 0.45 mW h cm(-3), which is higher than most reported supercapacitors. More importantly, the device performance remains efficient for 10,000 cycles. PMID:25329036

Gao, Yanping; Zhao, Junhong; Run, Zhen; Zhang, Guangqin; Pang, Huan

2014-12-01

243

Highly conductive and flexible polymer composites with improved mechanical and electromagnetic interference shielding performances  

NASA Astrophysics Data System (ADS)

New flexible and conductive materials (FCMs) comprising a quartz fiber cloth (QFC) reinforced multi-walled carbon nanotubes (MWCNTs)-carbon aerogel (QMCA) and poly(dimethylsiloxane) (PDMS) have been successfully prepared. The QMCA-PDMS composite with a very low loading of MWCNTs (~1.6 wt%) demonstrates enhanced performance in tensile strength (129.6 MPa), modulus (3.41 GPa) and electromagnetic interference (EMI) shielding efficiency (SE) (~16 dB in X-band (8.2-12.4 GHz) region). Compared to the QC (where MWCNTs were simply deposited on the QFCs without forming aerogel networks) based PDMS composite, a ~120%, 330% and 178% increase of tensile strength, modulus, and EMI SE was obtained, respectively. Moreover, the EMI SE of the QMCA-PDMS composite can further reach 20 dB (a SE level needed for commercial applications) with only 2 wt% MWCNTs. Furthermore, the conductivity of the QMCA-PDMS laminate can reach 1.67 S cm-1 even with very low MWCNTs (1.6 wt%), which still remains constant even after 5000 times bending and exhibits an increase of ~170% than that of MWCNT-carbon aerogel (MCA)-PDMS at 20% strain. Such intriguing performances are mainly attributed to their unique networks in QMCA-PDMS composites. In addition, these features can also protect electronics against harm from external forces and EMI, giving the brand-new FCMs huge potential in next-generation devices, like E-skin, robot joints and so on.New flexible and conductive materials (FCMs) comprising a quartz fiber cloth (QFC) reinforced multi-walled carbon nanotubes (MWCNTs)-carbon aerogel (QMCA) and poly(dimethylsiloxane) (PDMS) have been successfully prepared. The QMCA-PDMS composite with a very low loading of MWCNTs (~1.6 wt%) demonstrates enhanced performance in tensile strength (129.6 MPa), modulus (3.41 GPa) and electromagnetic interference (EMI) shielding efficiency (SE) (~16 dB in X-band (8.2-12.4 GHz) region). Compared to the QC (where MWCNTs were simply deposited on the QFCs without forming aerogel networks) based PDMS composite, a ~120%, 330% and 178% increase of tensile strength, modulus, and EMI SE was obtained, respectively. Moreover, the EMI SE of the QMCA-PDMS composite can further reach 20 dB (a SE level needed for commercial applications) with only 2 wt% MWCNTs. Furthermore, the conductivity of the QMCA-PDMS laminate can reach 1.67 S cm-1 even with very low MWCNTs (1.6 wt%), which still remains constant even after 5000 times bending and exhibits an increase of ~170% than that of MWCNT-carbon aerogel (MCA)-PDMS at 20% strain. Such intriguing performances are mainly attributed to their unique networks in QMCA-PDMS composites. In addition, these features can also protect electronics against harm from external forces and EMI, giving the brand-new FCMs huge potential in next-generation devices, like E-skin, robot joints and so on. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06092f

Chen, Mengting; Zhang, Ling; Duan, Shasha; Jing, Shilong; Jiang, Hao; Luo, Meifang; Li, Chunzhong

2014-03-01

244

Highly conductive and flexible polymer composites with improved mechanical and electromagnetic interference shielding performances.  

PubMed

New flexible and conductive materials (FCMs) comprising a quartz fiber cloth (QFC) reinforced multi-walled carbon nanotubes (MWCNTs)-carbon aerogel (QMCA) and poly(dimethylsiloxane) (PDMS) have been successfully prepared. The QMCA-PDMS composite with a very low loading of MWCNTs (?1.6 wt%) demonstrates enhanced performance in tensile strength (129.6 MPa), modulus (3.41 GPa) and electromagnetic interference (EMI) shielding efficiency (SE) (?16 dB in X-band (8.2-12.4 GHz) region). Compared to the QC (where MWCNTs were simply deposited on the QFCs without forming aerogel networks) based PDMS composite, a ?120%, 330% and 178% increase of tensile strength, modulus, and EMI SE was obtained, respectively. Moreover, the EMI SE of the QMCA-PDMS composite can further reach 20 dB (a SE level needed for commercial applications) with only 2 wt% MWCNTs. Furthermore, the conductivity of the QMCA-PDMS laminate can reach 1.67 S cm(-1) even with very low MWCNTs (1.6 wt%), which still remains constant even after 5000 times bending and exhibits an increase of ?170% than that of MWCNT-carbon aerogel (MCA)-PDMS at 20% strain. Such intriguing performances are mainly attributed to their unique networks in QMCA-PDMS composites. In addition, these features can also protect electronics against harm from external forces and EMI, giving the brand-new FCMs huge potential in next-generation devices, like E-skin, robot joints and so on. PMID:24577052

Chen, Mengting; Zhang, Ling; Duan, Shasha; Jing, Shilong; Jiang, Hao; Luo, Meifang; Li, Chunzhong

2014-04-01

245

Full scale demonstration of air-purifying pavement.  

PubMed

Experiments concerning a full-scale demonstration of air purifying pavement in Hengelo, The Netherlands, are reported. The full width of the street was provided with concrete pavement containing TiO? over a length of 150 m ("DeNOx street"). Another part of the street, about 100 m, was paved with normal paving blocks ("Control street"). The outdoor monitoring was done during 26 days for a period exceeding one year, and measured parameters included traffic intensity, NO, NO? and ozone concentrations, temperature, relative humidity, wind speed and direction, and the visible and UV light irradiance. Prior and parallel to these field measurements, the used blocks were also measured in the lab to assess their performance. The NOx concentration was, on average, 19% (considering the whole day) and 28% (considering only afternoons) lower than the obtained values in the Control street. Under ideal weather conditions (high radiation and low relative humidity) a NOx concentration decrease of 45% could be observed. PMID:23731840

Ballari, M M; Brouwers, H J H

2013-06-15

246

A high-performance flexible fibre-shaped electrochemical capacitor based on electrochemically reduced graphene oxide.  

PubMed

A fibre-shaped solid electrochemical capacitor based on electrochemically reduced graphene oxide has been fabricated, exhibiting high specific capacitance and rate capability, long cycling life and attractive flexibility. PMID:23183591

Li, Yingru; Sheng, Kaixuan; Yuan, Wenjing; Shi, Gaoquan

2013-01-11

247

Establishing a Dynamics Performance Envelope of a Flexible Tethered Satellite System for Planar and Non-Coplanar Models.  

NASA Astrophysics Data System (ADS)

A Tethered Satellite System (TSS) can be considered as a flexible in-orbit system. However, TSS is typically modelled as a rigid tethered system due to the complexity of its mathematical treatments. In this paper, mathematical models for a flexible tethered satellite system in both planar and co-planar states are developed. The flexible tethered satellite system consists of three rigid bodies with two flexible tethers each connecting two rigid bodies with one located in the centre serving as the mothership. The TSS motion includes tether deformations, rotational dynamics, and orbital mechanics. Three materials (e.g., tungsten wire, Spectra-2000, and diamond) that are commonly used for the tether are proposed as the reference materials; and it should be noted that the tether will undergo a spinning motion as well in the motorized option. In addition, the air drag perturbation is also considered since the entire TSS is flown around Low Earth Orbit (LEO), whereby the air-drag perturbation is dominant. A comprehensive analysis was performed for planar and non-coplanar models in order to establish a dynamics performance envelope with respect to the tether’s tension at different altitudes and air-drag. Bubnov-Galerkin method was employed in order to linearize the non-linear governing equations of elastic vibrations; and once the modal coordinates were obtained, they were substituted according to the equations corresponding to the energy conservation principle. Further, Lagrangian dynamics was utilized to establish the equations of motion of the entire TSS based on the chosen generalized coordinates. The proposed models were treated numerically and analysed accordingly. Then, a comparison study between the coplanar and non-coplanar models was done and the differences in their performances were observed and discussed. Although all materials have their own safe operation boundaries, the flexible TSS using Diamond shows a better dynamics performance than the other TSS options.

Teik Hong, Aaron Aw; Varatharajoo, Renuganth

248

Ultrathin porous NiCo2O4 nanosheet arrays on flexible carbon fabric for high-performance supercapacitors.  

PubMed

NiCo2O4 with higher specific capacitance is an excellent pseudocapacitive material. However, the bulk NiCo2O4 material prevents the achievement of high energy desity and great rate performance due to the limited electroactive surface area. In this work, NiCo2O4 nanosheet arrays were deposited on flexible carbon fabric (CF) as a high-performance electrode for supercapacitors. The NiCo2O4 arrays were constructed by interconnected ultrathin nanosheets (10 nm) with many interparticle pores. The porous feature of NiCo2O4 nanosheets increases the amount of electroactive sites and facilitates the electrolyte penetration. Hence, the NiCo2O4/CF composites exhibited a high specific capacitance of 2658 F g(-1) (2 A g(-1)), good rate performance, and superior cycling life, suggesting the NiCo2O4/CF is a promising electrode material for flexible electrochemical capacitors. PMID:23815528

Du, Jun; Zhou, Gang; Zhang, Haiming; Cheng, Chao; Ma, Jianmin; Wei, Weifeng; Chen, Libao; Wang, Taihong

2013-08-14

249

Pavement crack detection based on texture feature  

NASA Astrophysics Data System (ADS)

A novel automatic pavement crack detection approach based on texture feature is proposed. The bidirectional multi-level median filter is applied in pretreatment process to eliminate noise while maintain the details of crack edge. Improved center-symmetric local binary pattern (ICS-LBP) texture feature, local correlation texture feature and relative standard deviation texture feature are combined to detect the pavement cracks. Trained-decision strategy is applied to allocate each weight of features and texture features are extracted to train the weights. Experimental results show that the proposed algorithm provides better detection result in comparison with various crack extraction algorithms, and can detect the pavement crack quickly and effectively.

Zhang, Xiuhua; Chen, Yanjun; Hong, Hanyu

2011-11-01

250

Improvements to a Transport Model of Asphalt Binder Oxidation in Pavements: Pavement Temperature Modeling, Oxygen Diffusivity in Asphalt Binders and Mastics, and Pavement Air Void Characterization  

E-print Network

Although evidence is mounting that asphalt binder oxidizes in pavements, and that oxidation and subsequent hardening of asphalt binder has a profound effect on pavement durability, important implementation issues remain to be better understood...

Han, Rongbin

2012-07-16

251

Guidelines and specifications for the use of reclaimed aggregates in pavement. Final report  

SciTech Connect

The project focused on evaluating the performance of recycled concrete for use as a base material under hot mix asphalt pavements and as an aggregate in Portland cement concrete pavements. In order to meet this objective, several goals were established. First, published literature on RCA was reviewed and a survey of State Highway Agencies (SHA) was performed to determine the extent of use of RCA in highway projects. Second, the RCA was tested at the FDOT Material Lab in Gainesville, Florida, to determine the material properties. Third, by using the output from the falling weight deflectometer test along with the KENSLABS and KENLAYER computer programs (Huang, 1993), a theoretical analysis was performed to predict the number of repetitions before the pavements failed in both the fatigue and permanent deformation criteria. Lastly, nine design sections involving HMA and PCC pavements were constructed at the University of Central Florida`s Circular Accelerated Test Track (UCF-CATT) to evaluate the response of the pavement sections made with RCA under actual dual-wheel loading.

Chini, S.A.; Kuo, S.S.; Duxbury, J.P.; Monteiro, F.M.B.R.; Mbwambo, W.J.

1998-08-01

252

Inkjet printing of flexible high-performance carbon nanotube transparent conductive films by "coffee ring effect".  

PubMed

Transparent and flexible conductors are a major component in many modern optoelectronic devices, such as touch screens for smart phones, displays, and solar cells. Carbon nanotubes (CNTs) offer a good alternative to commonly used conductive materials, such as metal oxides (e.g. ITO) for flexible electronics. The production of transparent conductive patterns, and arrays composed of connected CNT "coffee rings" on a flexible substrate poly(ethylene terephthalate), has been reported. Direct patterning is achieved by inkjet printing of an aqueous dispersion of CNTs, which self-assemble at the rim of evaporating droplets. After post-printing treatment with hot nitric acid, the obtained TCFs are characterized by a sheet resistance of 156 ? sq(-1) and transparency of 81% (at 600 nm), which are the best reported values obtained by inkjet printing of conductive CNTs. This makes such films very promising as transparent conductors for various electronic devices, as demonstrated by using an electroluminescent device. PMID:25014193

Shimoni, Allon; Azoubel, Suzanna; Magdassi, Shlomo

2014-10-01

253

Inkjet printing of flexible high-performance carbon nanotube transparent conductive films by ``coffee ring effect''  

NASA Astrophysics Data System (ADS)

Transparent and flexible conductors are a major component in many modern optoelectronic devices, such as touch screens for smart phones, displays, and solar cells. Carbon nanotubes (CNTs) offer a good alternative to commonly used conductive materials, such as metal oxides (e.g. ITO) for flexible electronics. The production of transparent conductive patterns, and arrays composed of connected CNT ``coffee rings'' on a flexible substrate poly(ethylene terephthalate), has been reported. Direct patterning is achieved by inkjet printing of an aqueous dispersion of CNTs, which self-assemble at the rim of evaporating droplets. After post-printing treatment with hot nitric acid, the obtained TCFs are characterized by a sheet resistance of 156 ? sq-1 and transparency of 81% (at 600 nm), which are the best reported values obtained by inkjet printing of conductive CNTs. This makes such films very promising as transparent conductors for various electronic devices, as demonstrated by using an electroluminescent device.

Shimoni, Allon; Azoubel, Suzanna; Magdassi, Shlomo

2014-09-01

254

Ultrathin Cerium Orthovanadate Nanobelts for High-Performance Flexible All-Solid-State Asymmetric Supercapacitors.  

PubMed

Ultrathin CeVO4 nanobelts were successfully synthesized by a hydrothermal method. The thickness of a single nanobelt is about 2.4?nm, which can effectively shorten the ion diffusion and fasten the charge pathway. More importantly, ultrathin CeVO4 nanobelts and graphene are easily assembled as a flexible all-solid-state asymmetric device, which shows a highly flexible property and achieves a maximum energy density of 0.78?mW?h?cm(-3) and a high life cycle of >6000?cycles. PMID:25410018

He, Junzhi; Zhao, Junhong; Run, Zhen; Sun, Mengjun; Pang, Huan

2014-11-19

255

PCC Pavement Sustainability in New York Economy, Environment, and Society: 2 Out of 3 is Easy  

E-print Network

PCC Pavement Sustainability in New York Economy, Environment, and Society: 2 Out of 3 is Easy Bill PCC pavement sustainability strategy. NYSDOT recognizes that PCC pavements have "sustainable efforts, begging the question, "Is any pavement truly "sustainable?"" 1. PCC pavements, and pavement

256

Permeable Pavement Research - Edison, New Jersey  

EPA Science Inventory

This presentation provides the background and summary of results collected at the permeable pavement parking lot monitored at the EPA facility in Edison, NJ. This parking lot is surfaced with permeable interlocking concrete pavers (PICP), pervious concrete, and porous asphalt. ...

257

Pervious Pavement System Evaluation- Abstract 1  

EPA Science Inventory

Porous pavement is a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete pavers as a popular implementation. The pavers themselves are impermeable, but the spaces between the pavers are backfilled with washed, gra...

258

Transferable and flexible label-like macromolecular memory on arbitrary substrates with high performance and a facile methodology.  

PubMed

A newly designed transferable and flexible label-like organic memory based on a graphene electrode behaves like a sticker, and can be readily placed on desired substrates or devices for diversified purposes. The memory label reveals excellent performance despite its physical presentation. This may greatly extend the memory applications in various advanced electronics and provide a simple scheme to integrate with other electronics. PMID:23553715

Lai, Ying-Chih; Hsu, Fang-Chi; Chen, Jian-Yu; He, Jr-Hau; Chang, Ting-Chang; Hsieh, Ya-Ping; Lin, Tai-Yuan; Yang, Ying-Jay; Chen, Yang-Fang

2013-05-21

259

Transparent conducting films of hierarchically nanostructured polyaniline networks on flexible substrates for high-performance gas sensors.  

PubMed

Transparent chemical gas sensors are assembled from a transparent conducting film of hierarchically nanostructured polyaniline (PANI) networks fabricated on a flexible PET substrate, by coating silver nanowires (Ag NWs) followed by the in situ polymerization of aniline near the sacrificial Ag NW template. The sensor exhibits enhanced gas sensing performance at room temperature in both sensitivity and selectivity to NH3 compared to pure PANI film. PMID:25164185

Bai, Shouli; Sun, Chaozheng; Wan, Pengbo; Wang, Cheng; Luo, Ruixian; Li, Yaping; Liu, Junfeng; Sun, Xiaoming

2015-01-01

260

Study of the durability of demolition aggregates on pavements  

NASA Astrophysics Data System (ADS)

This work is an experimental contribution to the study of durability of various materials coming from the demolition of buildings for their use in the flexible infrastructures of pavements. However, these pavements undergo traffic loading which causes, in the long time permanent deformations and settlements thus generating significant degradations of materials. Various recent works aim at characterizing these materials. This work falls under this scope and gives an approach of the mechanical behavior and the response of these last to repetitive loadings. After identification of materials and the determination of the characteristics of hardness and durability, we studied their mechanical behavior with cyclic shearing on these three materials (aggregates of concrete, brick and concrete block). These tests enabled us to analyze the mechanisms which occur through the various parameters related to loading (the amplitude and the repetition of loading, the parameters related to materials (the water content, the density and the grain size distribution). The study of the durability of these materials consists on quantifying the degradation rate of the grains after the various tests and the grain size distribution which governs the amplitude of crushing.

Bachir, Melbouci; Fazia, Boudjemia

2009-06-01

261

Incorporating inspection decisions in pavement management  

Microsoft Academic Search

Pavement management systems need to address not only maintenance and rehabilitation (M&R) decisions, but also facility inspection decisions. The state of the art in pavement management is lacking of any consistent methodology for making such decisions on a cost-effectiveness basis. Such a methodology must recognize the presence of interactions between M&R and inspection decisions. These interactions argue for a joint

Samer Madanat

1993-01-01

262

Automatic inspection of pavement cracking distress  

Microsoft Academic Search

We present an image processing algorithm customized for high-speed, real-time inspection of pavement cracking. In the algorithm, a pavement image is divided into grid cells of 8×8 pixels, and each cell is classified as a noncrack or crack cell using the grayscale information of the border pixels. Whether a crack cell can be regarded as a basic element (or seed)

Yaxiong Huang; Bugao Xu

2006-01-01

263

SAFEgress: A Flexible Platform to Study the Effect of Human and Social Behaviors on Egress Performance  

E-print Network

SAFEgress: A Flexible Platform to Study the Effect of Human and Social Behaviors on Egress Department, 353 Serra Street, Room 146, Stanford, CA, 94305 latombe@cs.stanford.edu Keywords: Social behavior to incorporate human and social behaviors during evacautions. Simulation results on two scenarios are presented

Stanford University

264

Integration of structural and performance-oriented control in flexibly automated manufacturing  

Microsoft Academic Search

Advanced mechatronic systems increasingly are finding application in modern manufacturing, as high-tech production requirements dictate high levels of machine precision, automation and integration. A high-tech factory typically contains a variety of flexibly automated processing and material handling systems. Working together, these systems are capable of executing complex operations to produce sophisticated end products. At the same time, such systems must

Douglas A. Bodner; Jonghun Park; Spyros A. Reveliotis; Leon F. McGinnis

1999-01-01

265

The performance of flexible-membrane wave barriers in oblique incident waves  

Microsoft Academic Search

The interaction of oblique incident waves with a tensioned, inextensible, vertical flexible membrane wave barrier hinged at the sea floor is investigated in the context of two-dimensional linear wave-body interaction theory. First, an idealized system (tensioned vertical screen) is considered and analytic solutions are obtained. Second, a more practical system with the membrane tension provided by a buoy is investigated

I. H. Cho; S. T. Kee; M. H. Kim

1997-01-01

266

Fusing complementary images for pavement cracking measurements  

NASA Astrophysics Data System (ADS)

Cracking is a major pavement distress that jeopardizes road serviceability and traffic safety. Automated pavement distress survey (APDS) systems have been developed using digital imaging technology to replace human surveys for more timely and accurate inspections. Most APDS systems require special lighting devices to illuminate pavements and prevent shadows of roadside objects that distort cracks in the image. Most artificial lighting devices are laser based, and are either hazardous to unprotected people or require dedicated power supplies on the vehicle. This study was aimed to develop a new imaging system that can scan pavement surface at highway speed and determine the level of severity of pavement cracking without using any artificial lighting. The new system consists of dual line-scan cameras that are installed side by side to scan the same pavement area as the vehicle moves. Cameras are controlled with different exposure settings so that both sunlit and shadowed areas can be visible in two separate images. The paired images contain complementary details useful for reconstructing an image in which the shadows are eliminated. This paper intends to present (1) the design of the dual line-scan camera system, (2) a new calibration method for line-scan cameras to rectify and register paired images, (3) a customized image-fusion algorithm that merges the multi-exposure images into one shadow-free image for crack detection, and (4) the results of the field tests on a selected road over a long period.

Yao, Ming; Zhao, Zuyun; Yao, Xun; Xu, Bugao

2015-02-01

267

A sensitivity analysis of the Texas flexible pavement system  

E-print Network

Interactions for Dalhart - Asphalt Stabilized Base with Granular Subbase 103 43. 44. 45. 46. 47 Comparison Between Comparison Between Comparison Between Comparison Between Comparison Between 4, 000, 000 ESAL TFPS and AASHTO - Before Overlay . TFPS... sensitivity of different variables. 2) Establish relative importance of variables to better understand the design procedure. 3) Define program limitations. 4) Compare program designs to past designs. CHAPTER II EXPERIMENT DESIGN AND ANALYSIS The purpose...

Henry, Claude Patrick

2012-06-07

268

Thermal stability analysis under embankment with asphalt pavement and cement pavement in permafrost regions.  

PubMed

The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The maximum depth of temperature field under the embankment for concrete pavements and asphalt pavements was also studied by using the finite element method. The results of numerical analysis indicate that there were remarkable seasonal differences of the ground temperatures in superficial layer between asphalt pavement and concrete pavement. The maximum influencing depth of temperature field under the permafrost embankment for every pavement was under the depth of 8?m. The thawed cores under both embankments have close relation with the maximum thawed depth, the embankment height, and the service time. The effective measurements will be proposed to keep the thermal stabilities of highway embankment by the results. PMID:24027444

Junwei, Zhang; Jinping, Li; Xiaojuan, Quan

2013-01-01

269

Thermal Stability Analysis under Embankment with Asphalt Pavement and Cement Pavement in Permafrost Regions  

PubMed Central

The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The maximum depth of temperature field under the embankment for concrete pavements and asphalt pavements was also studied by using the finite element method. The results of numerical analysis indicate that there were remarkable seasonal differences of the ground temperatures in superficial layer between asphalt pavement and concrete pavement. The maximum influencing depth of temperature field under the permafrost embankment for every pavement was under the depth of 8?m. The thawed cores under both embankments have close relation with the maximum thawed depth, the embankment height, and the service time. The effective measurements will be proposed to keep the thermal stabilities of highway embankment by the results. PMID:24027444

Jinping, Li; Xiaojuan, Quan

2013-01-01

270

Asphalt Pavement Design using Results of Laboratory Fatigue Tests of Asphalt Mixtures  

Microsoft Academic Search

Fatigue tests with use of 4 Point Bending test were performed on conventional and innovative asphalt mixtures: typical asphalt concrete, high stiffness modulus asphalt concrete and stone mastic asphalt with conventional and special binders, multigrade or elastomer-bitumen. The results of fatigue testing were applied for development of fatigue characteristics of particular asphalt mixtures. Pavement design analysis was performed with design

Dariusz Sybilski; Wojciech Ba?kowski

2002-01-01

271

Impact of magnetic isolation on pointing system performance in the presence of structural flexibility  

NASA Technical Reports Server (NTRS)

The inertial pointing stability of a gimbal pointing system (AGS) was compared with a magnetic pointing/gimbal followup system (ASPS), under certain conditions of system structural flexibility and disturbance inputs from the gimbal support structure. Separate 3 degree-of-freedom (3DOF) linear models based on NASTRAN modal flexibility data for the gimbal and support structures were generated for the ASPS configurations. Using the models inertial pointing control loops providing 6dB of gain margin and 45 deg of phase margin were defined for each configuration. The pointing loop bandwidth obtained for the ASPS is more than twice the level achieved for the AGS configuration. The AGS limit is attributed to the gimbal and support structure flexibility. As a result of the higher ASPS pointing loop bandwidth and the disturbance rejection provided by the magnetic isolation ASPS pointing performane is significantly better than that of the AGS system. The low frequency peak of the ASPS transfer function from base disturbance to payload angular motion is almost 60dB lower than AGS low frequency peak.

Seller, J.

1985-01-01

272

POROUS PAVEMENT. PHASE I. DESIGN AND OPERATIONAL CRITERIA  

EPA Science Inventory

Design and operational criteria, utilization concepts, benefits and disadvantages, as well as other characteristics of porous pavements are presented in this report. Particular emphasis is placed on porous asphalt pavements, but the criteria and design approach are applicable to ...

273

Molecular mechanisms controlling pavement cell shape in Arabidopsis leaves  

Microsoft Academic Search

Pavement cells have an interlocking jigsaw puzzle-shaped leaf surface pattern. Twenty-three genes involved in the pavement\\u000a cell morphogenesis were discovered until now. The mutations of these genes through various means lead to pavement cell shape\\u000a defects, such as loss or lack of interdigitation, the reduction of lobing, gaps between lobe and neck regions in pavement\\u000a cells, and distorted trichomes. These

Pingping Qian; Suiwen Hou; Guangqin Guo

2009-01-01

274

Using the Multi-Depth Deflectometer to study pavement response  

E-print Network

the structural condition of existing pavements. In this study, the Multi-Depth Deflectometer (MDD) is used to measure the pavement response to dynamic loads. The NDD is installed inside a pavement to measure deflections of selected points in pavement layers... deflections. Thus, two procedures were available to backcalculate layer moduli from deflection data. The first was from surface deflections and the second was from depth deflections. A third procedure developed for backcalculation of layer moduli using...

Yazdani, Jamshed Iqbal

1989-01-01

275

Surface Distresses Detection of Pavement Based on Digital Image Processing  

Microsoft Academic Search

\\u000a Pavement crack is the main form of early diseases of pavement. The use of digital photography to record pavement images and\\u000a subsequent crack detection and classification has undergone continuous improvements over the past decade. Digital image processing\\u000a has been applied to detect the pavement crack for its advantages of large amount of information and automatic detection. The\\u000a applications of digital

Aiguo Ouyang; Chagen Luo; Chao Zhou

2010-01-01

276

Investigation of antenna frequency impact on assessing voids of asphalt pavements using GPR  

NASA Astrophysics Data System (ADS)

Ground Penetrating Radar (GPR) is a Non Destructive Testing (NDT) technique that has been developed and improved upon over the past 30 years. The technique is frequently utilized in order to evaluate and assess pavement structures. GPR, for pavement evaluation purposes, can be described as a remote sensing system that emits a short pulse, of electromagnetic energy, into the pavement, with a central frequency varying from 10 MHz up to 2.5GHz. The two most commonly utilized setups are air-coupled and ground-coupled antenna systems. For air-coupled systems, the antennas are suspended above the pavement surface and can operate at normal traffic speeds (up to ~ 80 Km/h). The major drawback of the air-coupled antenna is that penetration depth is limited. On the other hand, for ground-coupled systems the antennas are in direct contact with the pavement surface, providing for better signal penetration into the pavement structure; however ground coupled systems can achieve only limited operational speeds. As a generalized rule, increasing the GPR central operating frequency, increases the investigation resolution, while decreasing the overall depth of investigation In the light of the above, air-coupled systems have become increasingly popular for the evaluation of the part of the pavement structure, especially for the asphalt layers, while ground-coupled systems are utilized mostly in order to gather information from the entire pavement structure (up to ~ 3 m depth). The majority of GPR pavement studies are carried out with air-coupled horn antennas, as they can be implemented at driving speeds without need for road closures. For instance, the 1 GHz air-coupled horn antenna is commonly used for the estimation of pavement layer thickness. However signals generated by horn antenna systems must have sufficient quality to allow the performance of automated signal processing and qualitative data analysis, especially when pavement data more sensitive to the analysis parameters, such voids or moisture, is concerned. The implementation of the horn antenna method is dependent upon, amongst others, the resolution of the antenna in use. The present research work investigates the application of the GPR sensor technique to assess voids within the asphalt layers, with a focus on the air-coupled antenna penetration depth and resolution. For this purpose the dielectric properties of asphalt layer materials were estimated and related voids contents were evaluated based on data collected by an air-coupled GPR system, operating at a 1 GHz and alternatively a 2 GHz central frequency. The collected data is analyzed comparatively for the two antennas. Comparison results indicate differences between the voids determined from the 1 GHz and 2GHz antennas. These differences are further analyzed and evaluated for pavement quality control purposes. The indication of a relationship between the measured voids is also evaluated, while ground truth data is used for the validation of the GPR data analysis results. The above is presented and discussed thoroughly with the aim to assist pavement quality assurance systems

Plati, C.; Georgouli, K.; Loizos, A.

2012-04-01

277

Evaluation of non-metallic fiber reinforced concrete in new full depth pcc pavements. Final report  

SciTech Connect

This final report presents the construction and performance evaluation of a new full depth pavement, constructed with a new type non-metallic fiber reinforced concrete (NMFRC). The mixture proportions used, the quality control tests conducted for the evaluation of the fresh and hardened concrete properties, the procedure used for mixing, transporting, placing, consolidating, finishing, and curing of the concrete are described. Periodic inspection of the full depth pavement was done and this report includes the results of these inspections. The feasibility of using this NMFRC in the construction of highway structures has been discussed. The new NMFRC with enhanced fatigue, impact resistance, modulus of rupture, ductility and toughness properties is suitable for the construction of full depth pavements. However, a life-cycle cost analysis shows that NMFRC is not a favorable choice, because of it`s high initial cost.

Ramakrishnan, V.; Tolmare, N.S.

1998-12-30

278

High-performance bilayer flexible resistive random access memory based on low-temperature thermal atomic layer deposition  

PubMed Central

We demonstrated a flexible resistive random access memory device through a low-temperature atomic layer deposition process. The device is composed of an HfO2/Al2O3-based functional stack on an indium tin oxide-coated polyethylene terephthalate substrate. After the initial reset operation, the device exhibits a typical bipolar, reliable, and reproducible resistive switching behavior. After a 104-s retention time, the memory window of the device is still in accordance with excellent thermal stability, and a 10-year usage is still possible with the resistance ratio larger than 10 at room temperature and at 85°C. In addition, the operation speed of the device was estimated to be 500 ns for the reset operation and 800 ns for the set operation, which is fast enough for the usage of the memories in flexible circuits. Considering the excellent performance of the device fabricated by low-temperature atomic layer deposition, the process may promote the potential applications of oxide-based resistive random access memory in flexible integrated circuits. PMID:23421424

2013-01-01

279

Development on preventive maintenance management system for expressway asphalt pavements  

Microsoft Academic Search

In view of the status that there was no expressway pavement preventive maintenance management system at home and abroad at present, based on the technology theory obtained by the author and the demands and process of expressway asphalt pavement preventive maintenance management, preventive maintenance management system for expressway asphalt pavement (EPMMS (V1.0)) was developed. The work or functions of expressway

Hu Guoxiang; Li Jie

2010-01-01

280

Roads to Development: Experimental Evidence from Urban Road Pavement  

E-print Network

Roads to Development: Experimental Evidence from Urban Road Pavement Marco Gonzalez-Navarro UC peripheries in many developing country cities lack basic local public goods like pavement, water, sewerage pavement provision in Mexico. Our findings show that homes in streets that were paved increased their value

Silver, Whendee

281

Regular Inspection and Maintenance Guidance for Porous Pavements  

E-print Network

Regular Inspection and Maintenance Guidance for Porous Pavements Regular inspection and maintenance is critical to the effective operation of porous pavement. It is the responsibility of the owner to maintain the pavement in accordance with the minimum design standards. This page provides guidance on maintenance

282

PAVEMENT OVERLAY THICKNESS EVALUATION USING GROUND PENTRATING RADAR (GPR)  

E-print Network

PAVEMENT OVERLAY THICKNESS EVALUATION USING GROUND PENTRATING RADAR (GPR) Dwayne Harris, M.Sc., PG University, West Lafayette, IN 47907 jshan@ecn.purdue.edu ABSTRACT Accurate knowledge of pavement thickness is important information to have both at a network and project level. This information aids in pavement

Shan, Jie

283

Impact of Curing Methods on Curling of Concrete Pavements  

E-print Network

Impact of Curing Methods on Curling of Concrete Pavements Amir Hajibabaee Travis Ebisch Tyler Ley is Curling? Curling is when the edges of a concrete pavement (or slab) deflect up compared to the middle. Warping is the same thing only the edges deflect downward. curling warping #12;Why do pavements curl

284

Cosmogenic 3 He surface-exposure dating of stone pavements  

E-print Network

Cosmogenic 3 He surface-exposure dating of stone pavements: Implications for landscape evolution Mexico 87545 Chad T. Olinger ABSTRACT The formation of stone pavements, a ubiquitous gravel armor at the land surface in a time-transgressive manner. A newly proposed model for pavement evolution differs from

Ahmad, Sajjad

285

Integrated Materials and Construction Practices (IMCP) for Concrete Pavement  

E-print Network

Integrated Materials and Construction Practices (IMCP) for Concrete Pavement Workshop Participant Handbook Prepared for Prepared by Federal Highway Administration National Concrete Pavement Technology Center Office of Pavement Technology at Iowa State University 400 7th Street AW 2711 South Loop Drive

286

Fast Error Estimates For Indirect Measurements: Applications To Pavement Engineering  

E-print Network

Fast Error Estimates For Indirect Measurements: Applications To Pavement Engineering Carlos that is difficult to measure directly (e.g., lifetime of a pavement, efficiency of an engine, etc). To estimate y computation time. As an example of this methodology, we give pavement lifetime estimates. This work

Kreinovich, Vladik

287

Structural design of pavements with stabilized layers Animesh Das  

E-print Network

Structural design of pavements with stabilized layers Animesh Das Associate Professor, Department@iitk.ac.in The talk will primarily be divided in three parts, namely analysis of pavement structure, empirical design and composite pavements will be mentioned. The governing equations and the boundary conditions will be discussed

Das, Animesh

288

Graded Viscoelastic Approach for Modeling Asphalt Concrete Pavements  

E-print Network

Graded Viscoelastic Approach for Modeling Asphalt Concrete Pavements Eshan V. Dave'', William G of Illinois at Urb ana-Champaign Abstract. Asphalt concrete pavements exhibit severely graded properties viscoelastic model has been implemented within a numerical framework for the simulation of asphalt pavement

Paulino, Glaucio H.

289

Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally  

E-print Network

Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally Graded ­ II ­ Asphalt Pavements ­ Effect of Aging ­ Simulations ­ Concluding Remarks #12;3 Objectives Develop) Correspondence Principle based formulation Application: Asphalt concrete pavements (Part II) #12;4 Asphalt

Paulino, Glaucio H.

290

Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally  

E-print Network

Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally Graded ­ Verification ­ Concluding Remarks Part ­ II (Companion presentation) ­ Asphalt Pavements ­ Effect of Aging: Asphalt concrete pavements (Part II) E1 E2 E3 Eh 1 2 3 h #12;Graded Finite Elements Graded Elements

Paulino, Glaucio H.

291

RESEARCH REPORT 1250-1 EFFECT OF RECLAIMED ASPHALT PAVEMENT  

E-print Network

RESEARCH REPORT 1250-1 EFFECT OF RECLAIMED ASPHALT PAVEMENT ON BINDER PROPERTIES USING. Report Date September 1998 4. Title and Subtitle EFFECT OF RECLAIMED ASPHALT PAVEMENT ON BINDER with the Federal Highway Administration. 16. Abstract While the use of reclaimed asphalt pavement (RAP) in asphalt

Texas at Austin, University of

292

Application of Graded Finite Elements for Asphalt Pavements  

E-print Network

Application of Graded Finite Elements for Asphalt Pavements William G. Buttlar1 ; Glaucio H. Paulino2 ; and Seong Hyeok Song3 Abstract: Asphalt paving layers, particularly the surface course, exhibit: Fractures; Asphalt pavements; Finite element method; Material properties. Introduction Modern pavement

Paulino, Glaucio H.

293

User's guide: Cold-mix recycling of asphalt concrete pavements. Final report  

SciTech Connect

This guide provides the technical information required to implement the application of cold-mix recycling of asphalt concrete pavements. Included are details on areas on application, benefits/advantages, limitations/disadvantages, and costs associated with this technology. Information is provided on two demonstration sites at Fort Gillem, Georgia, and Fort Leavenworth, Kansas. Also provided is information concerning funding, procurement, maintenance, and performance monitoring. A fact sheet on recycling, contract specification example, and references are provided in the appendixes.... Asphalt pavement recycling, Emulsified asphalt cement, Cold milling, In-place cold-mix asphalt recycling, Cold-mix asphalt recycling, Recycling of asphalt.

Shoenberger, J.E.

1992-09-01

294

Enhanced adaptive filter-bank-based automated pavement crack detection and segmentation system  

NASA Astrophysics Data System (ADS)

We incorporate, evaluate, and assess the feasibility of using filter banks in automated pavement distress systems from a system level. We integrate a novel filter-bank-based distress segmentation method, which, unlike previously researched methods, does not depend on highpass data. In addition, we incorporate the standard Said Pearlman set partitioning in hierarchical trees compression coder into the automated pavement distress system, which is a first in this area of research. A third contribution of the research is a statistical detection algorithm that assists in overall system performance. Preliminary testing using images provided by the Georgia Department of Transportation demonstrate the promise of the proposed method.

Lettsome, Clyde A.; Tsai, Yi-Chang; Kaul, Vivek

2012-10-01

295

Correction: High-performance all-solid-state flexible micro-supercapacitor arrays with layer-by-layer assembled MWNT/MnOx nanocomposite electrodes.  

PubMed

Correction for 'High-performance all-solid-state flexible micro-supercapacitor arrays with layer-by-layer assembled MWNT/MnOx nanocomposite electrodes' by Geumbee Lee et al., Nanoscale, 2014, 6, 9655-9664. PMID:25365456

Lee, Geumbee; Kim, Daeil; Yun, Junyeong; Ko, Yongmin; Cho, Jinhan; Sook Ha, Jeong

2014-12-21

296

Correction: High-performance all-solid-state flexible micro-supercapacitor arrays with layer-by-layer assembled MWNT/MnOx nanocomposite electrodes  

NASA Astrophysics Data System (ADS)

Correction for `High-performance all-solid-state flexible micro-supercapacitor arrays with layer-by-layer assembled MWNT/MnOx nanocomposite electrodes' by Geumbee Lee et al., Nanoscale, 2014, 6, 9655-9664.

Lee, Geumbee; Kim, Daeil; Yun, Junyeong; Ko, Yongmin; Cho, Jinhan; Sook Ha, Jeong

2014-11-01

297

Pavement Sealcoat, PAHs, and the Environment  

NASA Astrophysics Data System (ADS)

Recent research by the USGS has identified coal-tar-based pavement sealants as a major source of polycyclic aromatic hydrocarbons (PAHs) to the environment. Coal-tar-based sealcoat is commonly used to coat parking lots and driveways and is typically is 20-35 percent coal tar pitch, a known human carcinogen. Several PAHs are suspected mutagens, carcinogens, and (or) teratogens. In the central and eastern U.S. where the coal-tar-based sealants dominate use, sum-PAH concentration in dust particles from sealcoated pavement is about 1,000 times higher than in the western U.S. where the asphalt-based formulation is prevalent. Source apportionment modeling indicates that particles from sealcoated pavement are contributing the majority of the PAHs to recent lake sediment in 35 U.S. urban lakes and are the primary cause of upward trends in PAHs in many of these lakes. Mobile particles from parking lots with coal-tar-based sealcoat are tracked indoors, resulting in elevated PAH concentrations in house dust. In a recently completed study, volatilization fluxes of PAHs from sealcoated pavement were estimated to be about 60 times fluxes from unsealed pavement. Using a wide variety of methods, the author and colleagues have shown that coal-tar-based sealcoat is a major source of PAHs to the urban environment and might pose risks to aquatic life and human health.

Van Metre, P. C.; Mahler, B. J.

2011-12-01

298

Hierarchical three-dimensional ZnCo?O? nanowire arrays/carbon cloth anodes for a novel class of high-performance flexible lithium-ion batteries.  

PubMed

Flexible electronics is an emerging and promising technology for next generation of optoelectronic devices. Herein, hierarchical three-dimensional ZnCo(2)O(4) nanowire arrays/carbon cloth composites were synthesized as high performance binder-free anodes for Li-ion battery with the features of high reversible capacity of 1300-1400 mAh g(-1) and excellent cycling ability even after 160 cycles with a capacity of 1200 mAh g(-1). Highly flexible full batteries were also fabricated, exhibiting high flexibility, excellent electrical stability, and superior electrochemical performances. PMID:22607457

Liu, Bin; Zhang, Jun; Wang, Xianfu; Chen, Gui; Chen, Di; Zhou, Chongwu; Shen, Guozhen

2012-06-13

299

High-performance NiO/Ag/NiO transparent electrodes for flexible organic photovoltaic cells.  

PubMed

Transparent electrodes with a dielectric-metal-dielectric (DMD) structure can be implemented in a simple manufacturing process and have good optical and electrical properties. In this study, nickel oxide (NiO) is introduced into the DMD structure as a more appropriate dielectric material that has a high conduction band for electron blocking and a low valence band for efficient hole transport. The indium-free NiO/Ag/NiO (NAN) transparent electrode exhibits an adjustable high transmittance of ?82% combined with a low sheet resistance of ?7.6 ?·s·q(-1) and a work function of 5.3 eV after UVO treatment. The NAN electrode shows excellent surface morphology and good thermal, humidity, and environmental stabilities. Only a small change in sheet resistance can be found after NAN electrode is preserved in air for 1 year. The power conversion efficiencies of organic photovoltaic cells with NAN electrodes deposited on glass and polyethylene terephthalate (PET) substrates are 6.07 and 5.55%, respectively, which are competitive with those of indium tin oxide (ITO)-based devices. Good photoelectric properties, the low-cost material, and the room-temperature deposition process imply that NAN electrode is a striking candidate for low-cost and flexible transparent electrode for efficient flexible optoelectronic devices. PMID:25148532

Xue, Zhichao; Liu, Xingyuan; Zhang, Nan; Chen, Hong; Zheng, Xuanming; Wang, Haiyu; Guo, Xiaoyang

2014-09-24

300

Stable Bending Performance of Flexible Organic Light-Emitting Diodes Using IZO Anodes  

PubMed Central

We report luminescent characteristics and mechanical stability of a flexible organic light-emitting diode (FOLED) using an amorphous ZnO-doped In2O3 (a-IZO) anode with a low sheet resistance of and a high optical transparency of 86%. The FOLED consisting of a-IZO/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS)/poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4, 8-diyl)] (F8BT)/LiF/Al exhibits the efficient luminescent characteristics, which are nearly identical with the photoluminescence spectrum of the organic emitting material in our FOLED. This observation clearly indicates that the luminescent characteristics of the FOLED are solely ascribed to molecular exciton formation within the F8BT layer, since exciplex and charge transfer exciton formation are strictly suppressed by both tunneling/thermionic injection of holes at the PEDOT:PSS/F8BT interface and enhanced hole transport. Furthermore, the use of the considerably flexible a-IZO anode and PEDOT:PSS acting as a strain-relief buffering material enables good retention of the efficient luminescent characteristics of the FOLED even after continuous bending of up to 1000 times. PMID:24071803

Kwak, Kiyeol; Cho, Kyoungah; Kim, Sangsig

2013-01-01

301

Ultrahigh Performance C60 Nanorod Large Area Flexible Photoconductor Devices via Ultralow Organic and Inorganic Photodoping  

PubMed Central

One dimensional single-crystal nanorods of C60 possess unique optoelectronic properties including high electron mobility, high photosensitivity and an excellent electron accepting nature. In addition, their rapid large scale synthesis at room temperature makes these organic semiconducting nanorods highly attractive for advanced optoelectronic device applications. Here, we report low-cost large-area flexible photoconductor devices fabricated using C60 nanorods. We demonstrate that the photosensitivity of the C60 nanorods can be enhanced ~400-fold via an ultralow photodoping mechanism. The photodoped devices offer broadband UV-vis-NIR spectral tuneability, exhibit a detectivitiy >109 Jones, an external quantum efficiency of ~100%, a linear dynamic range of 80?dB, a rise time 60?µs and the ability to measure ac signals up to ~250?kHz. These figures of merit combined are among the highest reported for one dimensional organic and inorganic large-area planar photoconductors and are competitive with commercially available inorganic photoconductors and photoconductive cells. With the additional processing benefits providing compatibility with large-area flexible platforms, these devices represent significant advances and make C60 nanorods a promising candidate for advanced photodetector technologies. PMID:24853479

Saran, Rinku; Stolojan, Vlad; Curry, Richard J.

2014-01-01

302

Oxygen-deficient hematite nanorods as high-performance and novel negative electrodes for flexible asymmetric supercapacitors.  

PubMed

Oxygen-deficient ?-Fe2 O3 nanorods with outstanding capacitive performance are developed and demonstrated as novel negative electrodes for flexible asymmetric supercapacitors. The asymmetric-supercapacitor device based on the oxygen-deficient ?-Fe2 O3 nanorod negative electrode and a MnO2 positive electrode achieves a maximum energy density of 0.41 mW·h/cm(3) ; it is also capable of charging a mobile phone and powering a light-emitting diode indicator. PMID:24496961

Lu, Xihong; Zeng, Yinxiang; Yu, Minghao; Zhai, Teng; Liang, Chaolun; Xie, Shilei; Balogun, Muhammad-Sadeeq; Tong, Yexiang

2014-05-21

303

Spills on Flat Inclined Pavements  

SciTech Connect

This report describes the general spill phenomenology for liquid spills occurring on relatively impermeable surfaces such as concrete or asphalt pavement and the development and application of a model to describe the time evolution of such spills. The discussion assumes evaporation and degradation are negligible and a homogeneous surface. In such an instance, the inherent interfacial properties determine the spatial extent of liquid spreading with the initial flow being controlled by the release rate of the spill and by the liquids resistance to flow as characterized by its viscosity. A variety of spill scenarios were simulated and successful implementation of the model was achieved. A linear relationship between spill area and spill volume was confirmed. The simulations showed spill rate had little effect on the final spill area. Slope had an insignificant effect on the final spill area, but did modify spill shape considerably. However, a fluid sink on the edge of the simulation domain, representing a storm drain, resulted in a substantial decrease in spill area. A bona fide effort to determine the accuracy of the model and its calculations remain, but comparison against observations from a simple experiment showed the model to correctly determine the spill area and general shape under the conditions considered. Further model verification in the form of comparison against small scale spill experiments are needed to confirm the models validity.

Simmons, Carver S.; Keller, Jason M.; Hylden, Jeff L.

2004-03-01

304

Acute pavement burns: a unique subset of burn injuries: a five-year review of resource use and cost impact.  

PubMed

This study focuses on the hospital care of a rare subset of burn injuries caused by contact with environmentally heated pavement, to further understand the required use of resources. This article aims to show that pavement burns are typically more severe than their flame/scald counterparts. A retrospective review of patients admitted to the burn center with injuries suffered from contact with hot pavement was performed. Patients were stratified on the presence or absence of altered mental status (AMS) and additional inciting factors. A representative sample of similarly sized flame and scald wounds treated in the same time period was compiled for comparison. Those with pavement burns had a significantly greater requirement for operative intervention, repetitive debridements, overall cost/percent burned, and lengthier hospital stays than those with flame/scald burns. Pavement burn victims with AMS were significantly more likely to require an operation, a greater cost/percent burned, and longer hospital stays than those without AMS. Pavement burns are significantly worse than similarly sized scald/flame burns with regards to length of stay and total hospital costs, and the necessity of initial and repetitive operative intervention. These discrepancies are even greater in patients with AMS as a concomitant inciting factor. It is apparent that these wounds often continue to deepen during a patient's stay, likely because of continued pressure on the wounds while recumbent. As such, this article highly recommends pressure off-loading beds and more aggressive debridement in the treatment of these unique injuries. PMID:25207798

Silver, Andrew G; Dunford, Gerrit M; Zamboni, William A; Baynosa, Richard C

2015-01-01

305

Breaking/cracking and seating concrete pavements. Final report  

SciTech Connect

This synthesis will be of interest to pavement designers, maintenance engineers, and others interested in reducing reflection cracking of asphalt overlays on portland cement concrete (PCC) pavement. Information is presented on the technique of breaking or cracking of the concrete pavement into small segments before overlaying with asphalt concrete. Asphalt concrete overlays on existing PCC pavements are subject to reflection cracking induced by thermal movements of PCC pavement. The report of the Transportation Research Board discusses the technique of breaking/cracking and seating of the existing PCC before an overlay as a means to reduce or eliminate reflection cracking.

Thompson, M.R.

1989-03-01

306

A Flexible System for Processing Clinical Performance Ratings: Illustrative Applications in a Residency and Four Clerkships.  

ERIC Educational Resources Information Center

The Performance Rating portion of the University of Arkansas for Medical Sciences (UAMS) Objective Test Scoring and Performance Rating (OTS-PR) system is designed to help the clinical teacher evaluate students' clinical performance. The system collects, processes, and reports ratings of learners' performances in clinical settings. The system's 160…

Cason, Gerald J.; And Others

307

Field monitoring and modeling of pavement response and service life consumption due to overweight truck traffic  

E-print Network

performance with respect to both rutting and fatigue cracking. Charts to evaluate the service life of the existing pavement subjected to OTTs are established in terms of the unit service life consumed due to the rutting and fatigue cracking with the various...

Oh, Jeong-Ho

2004-11-15

308

Project Information Form Project Title Evaluation of the Combined Effect of Recycled Asphalt Pavement (RAP),  

E-print Network

Project Information Form Project Title Evaluation of the Combined Effect of Recycled Asphalt Pavement (RAP), Recycled Asphalt Shingles (RAS), and Different Virgin Binder Sources on Performance the allowable RAP content to 25 percent in asphalt mixes. Caltrans-industry-academia task group has proposed

California at Davis, University of

309

Hydrological impacts evaluation of pervious pavement based on a storm water management model  

Microsoft Academic Search

Hydrological performances of pervious pavement were examined at a site within Little Mill Creek watershed in Lenexa, Kansas, USA using three hydrological indicators of peak flow rate, total runoff volume and runoff coefficient based on the 2-yr, 10-yr and 100-yr design rainfall events and a continuous ten year hourly rainfall record. Three scenarios of undeveloped, developed with no runoff control

Yan-wei Sun; Xiao-mei Wei; Christine A. Pomeroy

2011-01-01

310

Taichi-inspired rigid-flexible coupling cellulose-supported solid polymer electrolyte for high-performance lithium batteries  

PubMed Central

Inspired by Taichi, we proposed rigid-flexible coupling concept and herein developed a highly promising solid polymer electrolyte comprised of poly (ethylene oxide), poly (cyano acrylate), lithium bis(oxalate)borate and robust cellulose nonwoven. Our investigation revealed that this new class solid polymer electrolyte possessed comprehensive properties in high mechanical integrity strength, sufficient ionic conductivity (3 × 10?4?S cm?1) at 60°C and improved dimensional thermostability (up to 160°C). In addition, the lithium iron phosphate (LiFePO4)/lithium (Li) cell using such solid polymer electrolyte displayed superior rate capacity (up to 6 C) and stable cycle performance at 80°C. Furthermore, the LiFePO4/Li battery could also operate very well even at an elevated temperature of 160°C, thus improving enhanced safety performance of lithium batteries. The use of this solid polymer electrolyte mitigates the safety risk and widens the operation temperature range of lithium batteries. Thus, this fascinating study demonstrates a proof of concept of the use of rigid-flexible coupling solid polymer electrolyte toward practical lithium battery applications with improved reliability and safety. PMID:25183416

Zhang, Jianjun; Yue, Liping; Hu, Pu; Liu, Zhihong; Qin, Bingsheng; Zhang, Bo; Wang, Qingfu; Ding, Guoliang; Zhang, Chuanjian; Zhou, Xinhong; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

2014-01-01

311

Finite Element Investigation of the Deterioration of Doweled Rigid Pavements  

E-print Network

The purpose of this study is to describe the failure of concrete around dowel bars in jointed rigid pavements, and the resulting effect on the pavement performance. In fact, under repetitive vehicle loading, concrete in contact with the dowel bar deteriorates, particularly at the joint face. The degradation of concrete around the dowel negatively affects the latter's performance in terms of transferring wheel loads through vertical shear action. In this context, a nonlinear 3D Finite Element analysis was performed using the commercial FE code Abaqus (v-6.11). The FE model was validated with classical analytical solutions of shear and moment along the dowel. A concrete damaged plasticity model was used for the PCC slab to model the degradation of concrete matrix around the dowels under incremental loading. Results obtained show, among other things, that the degradation of concrete matrix around the dowel was found to initiate at the face of the joint and propagate towards the interior of the dowel. Also, results obtained confirmed the decrease in load transfer capability of the dowels as the PCC matrix deteriorates. The central dowels under the wheel load lost a significant portion of their load-transfer capacity as the PCC matrix around them deteriorated, while dowels farther away from the wheel load became more engaged in load transfer.

Ziad G. Ghauch

2013-06-23

312

Finite Element Investigation of the Deterioration of Doweled Rigid Pavements  

E-print Network

The purpose of this study is to describe the failure of concrete around dowel bars in jointed rigid pavements, and the resulting effect on the pavement performance. In fact, under repetitive vehicle loading, concrete in contact with the dowel bar deteriorates, particularly at the joint face. The degradation of concrete around the dowel negatively affects the latter's performance in terms of transferring wheel loads through vertical shear action. In this context, a nonlinear 3D Finite Element analysis was performed using the commercial FE code Abaqus (v-6.11). The FE model was validated with classical analytical solutions of shear and moment along the dowel. A concrete damaged plasticity model was used for the PCC slab to model the degradation of concrete matrix around the dowels under incremental loading. Results obtained show, among other things, that the degradation of concrete matrix around the dowel was found to initiate at the face of the joint and propagate towards the interior of the dowel. Also, resul...

Ghauch, Ziad G

2011-01-01

313

Chip Seals for Asphalt Concrete Pavements: A Proposed Emulsion Residue Specification and Existing Pavement Texture Evaluation  

E-print Network

seal emulsion must be applied. In this project, existing pavement macrotextures were measured at three chip seal projects immediately before construction using both the sand patch test and the circular track meter, CT Meter. The CT Meter was found...

Hoyt, Denise

2012-07-16

314

High-performance flexible ultraviolet photoconductors based on solution-processed ultrathin ZnO/Au nanoparticle composite films  

PubMed Central

Transparent ultraviolet (UV) ZnO thin film photoconductors are expected to have great applications in environmental monitoring, large-area displays, and optical communications, and they have drawn enormous interests in recent years. However, at present their performances are not satisfactory: the responsivity R (a parameter characterizing the sensitivity of the device to light) is not high (<1.0 × 103?AW?1), and the transparency T is not high either (<80%). Realizing high R and high T remains a big challenge today. In this paper, by employing solution-processed ultrathin ZnO/Au nanoparticle composite films, R as high as 1.51 × 105?AW?1 and T of over 90% are achieved. High values for detectivity D* and linear dynamic range LDR are also obtained, which are 2.05 × 1015 Jones and 60?dB, respectively. Moreover, such high-performance devices can be fabricated on flexible PET (polyethylene terephthalate) substrates. PMID:24589625

Jin, Zhiwen; Gao, Liang; Zhou, Qing; Wang, Jizheng

2014-01-01

315

High-performance flexible ultraviolet photoconductors based on solution-processed ultrathin ZnO/Au nanoparticle composite films  

NASA Astrophysics Data System (ADS)

Transparent ultraviolet (UV) ZnO thin film photoconductors are expected to have great applications in environmental monitoring, large-area displays, and optical communications, and they have drawn enormous interests in recent years. However, at present their performances are not satisfactory: the responsivity R (a parameter characterizing the sensitivity of the device to light) is not high (<1.0 × 103 AW-1), and the transparency T is not high either (<80%). Realizing high R and high T remains a big challenge today. In this paper, by employing solution-processed ultrathin ZnO/Au nanoparticle composite films, R as high as 1.51 × 105 AW-1 and T of over 90% are achieved. High values for detectivity D* and linear dynamic range LDR are also obtained, which are 2.05 × 1015 Jones and 60 dB, respectively. Moreover, such high-performance devices can be fabricated on flexible PET (polyethylene terephthalate) substrates.

Jin, Zhiwen; Gao, Liang; Zhou, Qing; Wang, Jizheng

2014-03-01

316

A comprehensive approach for the assessment of in-situ pavement density using GPR technique  

NASA Astrophysics Data System (ADS)

Proper construction of the asphalt pavement is a prerequisite to developing a long lasting roadway that does not require extensive future maintenance. This goal is achieved by verifying that design specifications are met through the use of quality assurance (QA) practices. The in-situ density is regarded as one of the most important controls used to ensure that a pavement being placed is of high quality because it is a good indicator of future performance. In-situ density is frequently assessed utilizing one or more of the following three methods: cores, nuclear density gauge measurements or non-nuclear density gauge measurements. Each of the above mentioned methods, however, have their distinct disadvantages. Cores, for example, are generally considered to be the most accurate means of measuring in-situ density, however, they are a time consuming and destructive test that introduces a defect into asphalt pavements. Because of the destructive nature associated with coring, contractors and agencies have alternatively used non-destructive nuclear and non-nuclear density gauges for quality control purposes. These instruments allow for a more rapid assessment of the in-situ density, allowing measurements to be taken even during the pavement's construction. The disadvantage of these gauges are that they provide density readings only at discrete locations of the asphalt pavement mat, while no consensus exists among pavement researchers on the proper correlation between the gauges and core density. In recent years, numerous alternative methods have been introduced for the assessment of in-situ density, both during asphalt pavement construction and afterwards. These methods include, amongst others, intelligent compaction, thermal imaging and ground penetrating radar (GPR). Among these methods, GPR has been defined as both a technically feasible and promising method for the nondestructive, rapid, and continuous evaluation of in-situ asphalt pavement density based on electromagnetic mixing (EM) theory, through the utilization of proper models. These models enable the prediction of asphalt mixture density dependent on its bulk dielectric constant as measured by the GPR, the dielectric properties of the asphalt mix materials, as well as other material information. The goal of the present study is to attempt to verify the prediction performance of various density models. To accomplish this goal GPR surveys were carried out in the field during asphalt pavement construction to evaluate the density results due to different compaction modes. The GPR data was analyzed to calculate the appropriate asphalt mix dielectric properties needed for the activation of the considered density prediction models. Predicted densities were compared with densities of the field cores extracted from the as-built asphalt pavement prior to trafficking. It was found that the predicted density values were significantly lower when compared to the ground truth data. A further investigation of the effect of temperature on GPR readings showed that GPR seems to overestimate the in-situ density. However, this approach could be used effectively to evaluate the performance of different compaction methods and set up the compaction pattern that is needed to achieve the desired asphalt pavement density.

Plati, Christina; Georgiou, Panos; Loizos, Andreas

2013-04-01

317

Performance and parameter variation of flexible organic thin film transistors in multicomponent organic sensors  

NASA Astrophysics Data System (ADS)

Here we report on the fabrication and detailed characterization of flexible low-voltage organic thin-film transistors directly integrated with pyro- and piezoelectric sensors. The functional layer of the capacitive sensors is a ferroelectric fluoropolymer. The transistors on the other hand are based on a high-k nanocomposite gate dielectric and on pentacene as the organic semiconductor and can be operated well below 5V. It is shown, that the transistors can be fabricated on the fluororpolymer layer. Since the control of parameter spread is a very important topic in large area electronics, it was attempted to investigate the homogeneity of a significant set of devices by individual assessment of the layer composition and thickness, the pentacene morphology, the actual geometry and the electrical parameters. It turned out that starting from the measured device parameters such as layer thickness, capacitance, channel dimension, grain size and threshold voltage, the drain current can be calculated with high accuracy in a specified operation point. In addition, it is shown that the main influence on the parameter spread originates from the variations in the threshold voltage. Storage in air destroys the transistors on the long term, whereas bias stress measurements under inert conditions reveal that the interfaces are very stable.

Stadlober, Barbara; Fian, Alex; Haase, Anja; Kraker, Elke; Zirkl, Martin; Scheipl, Gregor; Jakopic, Georg

2010-08-01

318

Reconstruction of a pavement geothermal deicing system  

SciTech Connect

In 1948, US 97 in Klamath Falls, Oregon was routed over Esplanade Street to Main Street and through the downtown area. In order to widen the bridge across the US Bureau of Reclamation A Canal and to have the road cross under the Southern Pacific Railroad main north-south line, a new bridge and roadway were constructed at the beginning of this urban route. Because the approach and stop where this roadway intersected Alameda Ave (now Hwy 50 -- Eastside Bypass) caused problems with traffic getting traction in the winter on an adverse 8% grade, a geothermal experiment in pavement de-icing was incorporated into the project. A grid system within the pavement was connected to a nearby geothermal well using a downhole heat exchanger (DHE). The 419-foot well provided heat to a 50-50 ethylene glycol-water solution that ran through the grid system at about 50 gpm. This energy could provide a relatively snow free pavement at an outside temperature of {minus}10 F and snowfall up to 3 inches per hour, at a heat requirement of 41 Btu/hr/ft{sup 2}. Over time, the well temperature dropped from 143 to 98 F at the surface. The bridge and surface pavement, geothermal well, and associated equipment were modified. This paper describes the modifications.

Lund, J.W. [Geo-Heat Center, Klamath Falls, OR (United States)

1999-03-01

319

Desert pavement study at Amboy, California  

NASA Technical Reports Server (NTRS)

Desert pavement is a general term describing a surface that typically consists of a thin layer of cm-sized rock fragments set on top of a layer of finer material in which no fragments are found. An understanding of desert pavement is important to planetary geology because they may play a major role in the formation and visibility of various aeolian features such as wind streaks, which are important on Mars and may be important on Venus. A field study was conducted in Amboy, California to determine the formation mechanism of desert pavements. The probable sequence of events for the formation and evolution of a typical desert pavement surface, based on this experiment and the work of others, is as follows. Starting with a layer of surface material consisting of both fine particles and rock fragments, aeolian deflation will rapidly erode the surface until an armored lag is developed, after which aeolian processes become less important. The concentration of fragments then slowly increases as new fragments are brought to the surface from the subsurface and as fragments move downslope by sheet wash. Sheet wash would be responsible for removing very fine particles from the surface and for moving the fragments relative to one another, forming interlocks.

Williams, S.; Greeley, R.

1984-01-01

320

Asphalt Oxidation Kinetics and Pavement Oxidation Modeling  

E-print Network

not considered in the model such as the effect of small aggregate particles on oxygen diffusion. Carbonyl area and viscosity of binders recovered from field cores of three pavements in Texas were measured and were used for model calibration and validation...

Jin, Xin

2012-07-16

321

Self-Poled Transparent and Flexible UV Light-Emitting Cerium Complex-PVDF Composite: A High-Performance Nanogenerator.  

PubMed

Cerium(III)-N,N-dimethylformamide-bisulfate [Ce(DMF)(HSO4)3] complex is doped into poly(vinylidene fluoride) (PVDF) to induce a higher yield (99%) of the electroactive phases (?- and ?-phases) of PVDF. A remarkable enhancement of the output voltage (?32 V) of a nanogenerator (NG) based on a nonelectrically poled cerium(III) complex containing PVDF composite film is achieved by simple repeated human finger imparting, whereas neat PVDF does not show this kind of behavior. This high electrical output resembles the generation of self-poled electroactive ?-phase in PVDF due to the electrostatic interactions between the fluoride of PVDF and the surface-active positive charge cloud of the cerium complex via H-bonding and/or bipolar interaction among the opposite poles of cerium complex and PVDF, respectively. The capacitor charging capability of the flexible NG promises its applicability as piezoelectric-based energy harvester. The cerium(III) complex doped PVDF composite film exhibit an intense photoluminescence in the UV region, which might be due to a participation of electron cloud from negative pole of bipolarized PVDF. This fact may open a new area for prospective development of high-performance energy-saving flexible solid-state UV light emitters. PMID:25523039

Garain, Samiran; Sinha, Tridib Kumar; Adhikary, Prakriti; Henkel, Karsten; Sen, Shrabanee; Ram, Shanker; Sinha, Chittaranjan; Schmeißer, Dieter; Mandal, Dipankar

2015-01-21

322

Flexible Sigmoidoscopy  

MedlinePLUS

... 490 KB) Spanish Version Alternate Language URL Español Flexible Sigmoidoscopy Page Content DUE TO UNFORESEEN CIRCUMSTANCES, PUBLICATION ... through Research For More Information Acknowledgments What is flexible sigmoidoscopy? Flexible sigmoidoscopy is a test that uses ...

323

Simplified Solution for Periodic Thermal Discontinuities in Asphalt Overlays Bonded to Rigid Pavements  

E-print Network

Simplified Solution for Periodic Thermal Discontinuities in Asphalt Overlays Bonded to Rigid discontinuities distributed in a hot mix asphalt overlay bonded to a rigid pavement, where the length Database subject headings: Thermal stresses; Fracture mechanics; Asphalt pavements; Rigid pavements

Paulino, Glaucio H.

324

Evaluation and prediction of moisture-induced damage in asphaltic concrete pavements  

SciTech Connect

The indirect tensile strength (ITS) test using Tunnicliff and Root moisture conditioning procedures, and boiling test was evaluated to determine the moisture susceptibility of asphaltic concrete specimens. A procedure was developed for inventorying stripping in asphaltic concrete pavements. Cores were obtained from existing pavements and then tested in the laboratory for moisture susceptibility. ITS testing and visual strip ratings were used to evaluate moisture-induced damage in the flexible pavements. Moisture susceptibility of asphaltic concrete mixtures was evaluated in the laboratory using various destructive test methods. A procedure was developed to compare the results of the field-sampling program with the laboratory test results. It was shown, through a laboratory testing procedure, that various asphalt cement sources of the same grade (AC-20), when used with different aggregates and antistrip additives, yielded different ITS values and visual strip ratings. Using the laboratory results, the ACMODAS (Asphalt Concrete Moisture Damage Analysis System) computer program was used to predict consequences of moisture-induced damage in asphaltic concrete mixtures.

Amirkhanian, S.N.

1987-01-01

325

Solid-State High Performance Flexible Supercapacitors Based on Polypyrrole-MnO2-Carbon Fiber Hybrid Structure  

NASA Astrophysics Data System (ADS)

A solid-state flexible supercapacitor (SC) based on organic-inorganic composite structure was fabricated through an ``in situ growth for conductive wrapping'' and an electrode material of polypyrrole (PPy)-MnO2 nanoflakes-carbon fiber (CF) hybrid structure was obtained. The conductive organic material of PPy greatly improved the electrochemical performance of the device. With a high specific capacitance of 69.3 F cm-3 at a discharge current density of 0.1 A cm-3 and an energy density of 6.16 × 10-3 Wh cm-3 at a power density of 0.04 W cm-3, the device can drive a commercial liquid crystal display (LCD) after being charged. The organic-inorganic composite active materials have enormous potential in energy management and the ``in situ growth for conductive wrapping'' method might be generalized to open up new strategies for designing next-generation energy storage devices.

Tao, Jiayou; Liu, Nishuang; Ma, Wenzhen; Ding, Longwei; Li, Luying; Su, Jun; Gao, Yihua

2013-07-01

326

Solid-State High Performance Flexible Supercapacitors Based on Polypyrrole-MnO2-Carbon Fiber Hybrid Structure  

PubMed Central

A solid-state flexible supercapacitor (SC) based on organic-inorganic composite structure was fabricated through an “in situ growth for conductive wrapping” and an electrode material of polypyrrole (PPy)-MnO2 nanoflakes-carbon fiber (CF) hybrid structure was obtained. The conductive organic material of PPy greatly improved the electrochemical performance of the device. With a high specific capacitance of 69.3?F cm?3 at a discharge current density of 0.1?A cm?3 and an energy density of 6.16 × 10?3?Wh cm?3 at a power density of 0.04?W cm?3, the device can drive a commercial liquid crystal display (LCD) after being charged. The organic-inorganic composite active materials have enormous potential in energy management and the “in situ growth for conductive wrapping” method might be generalized to open up new strategies for designing next-generation energy storage devices. PMID:23884478

Tao, Jiayou; Liu, Nishuang; Ma, Wenzhen; Ding, Longwei; Li, Luying; Su, Jun; Gao, Yihua

2013-01-01

327

Permeable pavement is a system that allows rainwater and runoff to move through the pavement's porous surface to a storage layer below.  

E-print Network

Permeable pavement is a system that allows rainwater and runoff to move through the pavement. It has been shown by decades of scientific research that permeable pavements reduce runoff volumes. Research has also shown that the stormwater that flows through the layers of a permeable pavement system

Goodman, Robert M.

328

Flexibly Global? Performing Culture and Identity in an Age of Uncertainty  

ERIC Educational Resources Information Center

Presented as a symbolic interactive messy performance text, Michael Giardina sutures himself into and through the landscape of global social relations, including his own interpretive interactions of disconnection and reconnection with place, home, and nation. In so doing, and in these collages of lived textuality, he examines the complex,…

Giardina, Michael D.

2009-01-01

329

Platypus: Design and Implementation of a Flexible High Performance Object Store  

Microsoft Academic Search

This paper reports the design and implementation of Platypus, a trans- actional object store. The twin goals of fle xibility and performance dominate the design of Platypus. The design includes: support for SMP concurrency; stand- alone, client-server and client-peer distribution configurations; configurable log- ging and recovery; and object management which can accommodate garbage col- lection and clustering mechanisms. The first

Zhen He; Stephen M. Blackburn; Luke Kirby; John N. Zigman

2000-01-01

330

Analysis of durability of advanced cementitious materials for rigid pavement construction in California  

SciTech Connect

Caltrans specifications for the construction of rigid pavements require rapid setting, high early strength, superior workability concrete with a desired 30+ year service life. These strict specifications provide the motivations for the investigation of advanced cementitious materials for pavement construction. The cementitious materials under consideration by Caltrans may be classified into four categories: Portland cements and blends, calcium aluminate cements and blends, calcium sulfoaluminate cements, and fly ash-based cements. To achieve the desired 30+ year design life, it is essential to select materials that are expected to exhibit long-term durability. Because most of the cementitious materials under consideration have not been extensively used for pavement construction in the United States, it is essential to characterize the long-term durability of each material. This report provides general information concerning the deleterious reactions that may damage concrete pavements in California. The reactions addressed in this report are sulfate attack, aggregate reactions, corrosion of reinforcing steel, and freeze-thaw action. Specifically, the expected performance of Portland cements and blends, calcium aluminate cements and blends, calcium sulfoaluminate cements, and fly ash-based cements are examined with regard to each of the deleterious reactions listed. Additional consideration is given to any deterioration mechanism that is particular to any of these cement types. Finally, the recommended test program for assessing potential long-term durability with respect to sulfate attack is described.

Kurtis, K.E.; Monteiro, P.

1999-04-01

331

Numerical Investigation of Design Strategies to Achieve Long-Life Pavements  

E-print Network

Increasing the HMA base thickness and modifying the HMA mixture properties to improve the resistance to fatigue cracking are among the most popular methods for achieving long-lasting pavements. Such methods are based on the idea of reducing the tensile strain at the bottom of the HMA layer below the Fatigue Endurance Limit (FEL), a level of strain below which no cumulative damage occurs to the HMA mixture. This study investigates the effectiveness of several design strategies involved in long-life, perpetual pavement design. A 3D Finite Element model of the pavement involving a linear viscoelastic constitutive model for HMA materials and non-uniform tire contact stresses is developed using ABAQUS 6.11. The effects of asphalt base course thickness and mixture type, rich binder layer, and aggregate subbase layer are examined. Four asphalt base course mixture types, namely dense graded, polymer modified, high modulus, and standard binder, are studied as a function of the asphalt base course thickness. The results underline a better performance of the high-modulus asphalt base, as compared to the other base course mixtures. The aggregate subbase layer on top of subgrade soil showed a relatively minor effect on the longitudinal and lateral strain response at the bottom of asphalt base course. The addition of a rich binder layer at the bottom of the asphalt base course showed a significant reduction in tensile strains. Tables are provided as a guideline to assess the different alternatives in design of long-life perpetual pavements.

Grace G. Abou-Jaoude; Ziad G. Ghauch

2012-03-30

332

Thermal cracking of rubber modified pavements, May 1995. Final report  

SciTech Connect

In accordance with the original ISTEA mandate (1991) to use crumb tire rubber in pavements, Alaska would be required to use about 250 tons of used tire rubber starting in 1994 and increasing to about 1,000 tons of rubber in 1997 and each year thereafter. A number of pavements using crumb rubber modifiers have been built in the state and have been in service for periods of 8 to 15 years. Knowledge of the behavior of these rubber-modified pavements under extreme climate conditions, particularly in relation to their low temperature cracking resistance, is necessary for future design and construction of rubberized pavements in Alaska. This report presents results of a study to determine the low temperature cracking resistance of rubber modified pavements in Alaska in comparison with conventional asphalt concrete pavements.

Raad, L.; Yuan, X.; Saboundjian, S.

1995-05-01

333

MODELING PAVEMENT DETERIORATION PROCESSES BY POISSON HIDDEN MARKOV MODELS  

NASA Astrophysics Data System (ADS)

In pavement management, it is important to estimate lifecycle cost, which is composed of the expenses for repairing local damages, including potholes, and repairing and rehabilitating the surface and base layers of pavements, including overlays. In this study, a model is produced under the assumption that the deterioration process of pavement is a complex one that includes local damages, which occur frequently, and the deterioration of the surface and base layers of pavement, which progresses slowly. The variation in pavement soundness is expressed by the Markov deterioration model and the Poisson hidden Markov deterioration model, in which the frequency of local damage depends on the distribution of pavement soundness, is formulated. In addition, the authors suggest a model estimation method using the Markov Chain Monte Carlo (MCMC) method, and attempt to demonstrate the applicability of the proposed Poisson hidden Markov deterioration model by studying concrete application cases.

Nam, Le Thanh; Kaito, Kiyoyuki; Kobayashi, Kiyoshi; Okizuka, Ryosuke

334

HFS: a performance-oriented flexible file system based on building-block compositions  

Microsoft Academic Search

The Hurricane File System (HFS) is designed for (potentially large-scale) shared-memory multiprocessors. Its architecture is based on the principle that, in order to maximize performance for applications with diverse requirements, a file system must support a wide variety of file structures, file system policies, and I\\/O interfaces. Files in HFS are implemented using simple building blocks composed in potentially complex

Orran Krieger; Michael Stumm

1997-01-01

335

HFS: a performance-oriented flexible file system based on building-block compositions  

Microsoft Academic Search

The Hurricane File System (HFS) is designed for (potentially large-scale) shared-memory multiprocessors. Its architecture is based on the principle that, in order to maximize performance for applications with diverse requirements, a file system must support a wide variety of file structures, file system policies, and I\\/O interfaces. Files in HFS are imple- mented using simple building blocks composed in potentially

Orran Krieger; Michael Stumm

1996-01-01

336

Silicon carbide high performance optics: a cost-effective, flexible fabrication process  

NASA Astrophysics Data System (ADS)

Silicon carbide may well be the best known material for the manufacture of high performance optical components. This material offers many advantages over glasses and metals that have historically been used in high performance optical systems. A combination of extremely high specific stiffness (E/r), high thermal conductivity and outstanding dimensional stability make silicon carbide superior overall to beryllium and low-expansion glass ceramics. A major impediment to wide use of silicon carbide in optical systems has been the cost associated with preliminary shaping and final finishing of silicon carbide. Because silicon carbide is an extremely hard and strong material, precision machining can only be done with expensive diamond tooling on very stiff high quality machine tools. Near-net-shape slip casting of silicon carbide can greatly reduce the cost of silicon carbide mirror substrates but this process still requires significant diamond grinding of the cast components. The process described here begins by machining the component from all special type of graphite. This graphite can rapidly be machined with conventional multi-axis CNC machine tools to achieve any level of complexity and lightweighting required. The graphite is then directly converted completely to silicon carbide with very small and very predictable dimensional change. After conversion to silicon carbide the optical surface is coated with very fine grain CVD silicon carbide which is easily polished to extreme smoothness. Details of the fabrication process are described and photos and performance specifications of an eight-inch elliptical demonstration mirror are provided.

Casstevens, John M.; Rashed, Abuagela; Plummer, Ronald; Bray, Don; Gates, Rob L.; Lara-Curzio, Edgar; Ferber, Matt K.; Kirkland, Tim

2001-12-01

337

Numerical analysis of active chordwise flexibility on the performance of non-symmetrical flapping airfoils  

NASA Astrophysics Data System (ADS)

This paper investigates the effect of active chordwise flexing on the lift, thrust and propulsive efficiency of three types of airfoils. The factors studied are the flexing center location, standard two-sided flexing as well as a type of single-sided flexing. The airfoils are simulated to flap with four configurations, and the effects of flexing under these configurations are investigated. Results show that flexing is not necessarily beneficial for the performance of the airfoils. However, with the correct parameters, efficiency is as high as 0.76 by placing the flexing centre at the trailing edge. The average thrust coefficient is more than twice as high, from 1.63 to 3.57 with flapping and flexing under the right conditions. Moreover, the single-sided flexing also gives an average lift coefficient as high as 4.61 for the S1020 airfoil. The shape of the airfoil does alter the effect of flexing too. Deviating the flexing phase angle away from 90° does not give a significant improvement to the airfoil’s performance. These results greatly enhance the design of a better performing ornithopter wing.

Tay, W. B.; Lim, K. B.

2010-01-01

338

Large-scale graphene micropattern nano-biohybrids: high-performance transducers for FET-type flexible fluidic HIV immunoassays.  

PubMed

Large-scale FET-type graphene micropattern (GM) nano-biohybrid-based immunosensor (GMNS) is fabricated in a controlled fashion to detect human immunodeficiency virus 2 antibody. Flexible GMNS shows a highly sensitive response and excellent mechanical bendability. The flexible GMNS in fluidic systems also has a stable response. This is the first experimental demonstration of a large-scale flexible fluidic FET-type immunoassay based on GM nano-biohybrids. PMID:23744620

Kwon, Oh Seok; Lee, Seung Hwan; Park, Seon Joo; An, Ji Hyun; Song, Hyun Seok; Kim, Taejoon; Oh, Joon Hak; Bae, Joonwon; Yoon, Hyeonseok; Park, Tai Hyun; Jang, Jyongsik

2013-08-14

339

Smart Road Pavement Research HomePage  

NSDL National Science Digital Library

Dubbed "the Smart Road" by Virginia's Department of Transportation, this full-scale facility for pavement research and evaluation of high-tech transportation systems uses computers, electronics, and satellites to create a realistic environment for collecting traffic and environmental data under controlled conditions, "and should advance the general understanding of the engineering behavior of pavement systems." This site, from the Virginia Tech Civil Engineering Materials Program, provides information from the researchers who have designed the Smart Road. The page contains a description of the project's current status, an explanation of objectives, construction photos, a detailed description of the instrumentation used, and data. Note, the research plan and testing links are still under construction. This site introduces an interesting project for highway and transportation engineers.

340

Ground rubber use in asphalt paving mixtures: A design and performance evaluation. Executive summary. Final report, 1 July 1991-30 June 1994  

SciTech Connect

The main objectives of the study were: (1) To determine if existing pavement mixture design procedures could be used in the design of rubberized pavements; (2) To determine the performance characteristics of rubberized mixtures in terms of crackng and rutting potential; (3) To compare the performance of rubberized and conventional pavement systems using a computer based performance prediction model; (4) To compare the life cycle costs of rubberized and conventional pavement systems.

Khosla, N.P.; Malpass, G.A.

1994-10-01

341

High-performance flexible thin-film transistors fabricated using print-transferrable polycrystalline silicon membranes on a plastic substrate  

NASA Astrophysics Data System (ADS)

Inexpensive polycrystalline Si (poly-Si) with large grain size is highly desirable for flexible electronics applications. However, it is very challenging to directly deposit high-quality poly-Si on plastic substrates due to processing constrictions, such as temperature tolerance and residual stress. In this paper, we present our study on poly-Si membranes that are stress free and most importantly, are transferrable to any substrate including a low-temperature polyethylene terephthalate (PET) substrate. We formed poly-Si-on-insulator by first depositing small-grain size poly-Si on an oxidized Si wafer. We then performed high-temperature annealing for recrystallization to obtain larger grain size. After selective doping on the poly-Si-on-insulator, buried oxide was etched away. By properly patterning the poly-Si layer, residual stress in the released poly-Si membranes was completely relaxed. The flat membrane topology allows the membranes to be print transferred to any substrates. High-performance TFTs were demonstrated on the transferred poly-Si membranes on a PET substrate.

Qin, Guoxuan; Yuan, Hao-Chih; Yang, Hongjun; Zhou, Weidong; Ma, Zhenqiang

2011-02-01

342

High-performance flexible ultraviolet photoconductors based on solution-processed ultrathin ZnO/Au nanoparticle composite films.  

PubMed

Transparent ultraviolet (UV) ZnO thin film photoconductors are expected to have great applications in environmental monitoring, large-area displays, and optical communications, and they have drawn enormous interests in recent years. However, at present their performances are not satisfactory: the responsivity R (a parameter characterizing the sensitivity of the device to light) is not high (<1.0 × 10(3)?AW(-1)), and the transparency T is not high either (<80%). Realizing high R and high T remains a big challenge today. In this paper, by employing solution-processed ultrathin ZnO/Au nanoparticle composite films, R as high as 1.51 × 10(5)?AW(-1) and T of over 90% are achieved. High values for detectivity D* and linear dynamic range LDR are also obtained, which are 2.05 × 10(15) Jones and 60?dB, respectively. Moreover, such high-performance devices can be fabricated on flexible PET (polyethylene terephthalate) substrates. PMID:24589625

Jin, Zhiwen; Gao, Liang; Zhou, Qing; Wang, Jizheng

2014-01-01

343

Ecological restoration and soil improvement performance of the seabuckthorn flexible dam in the Pisha Sandstone area of Northwestern China  

NASA Astrophysics Data System (ADS)

Soil erosion of the Pisha Sandstone area of Loess Plateau is extremely severe in China. The Pisha Sandstone is very hard when it is dry, while it is very frail when wet. The seabuckthorn flexible dam (SFD), a type of ecological engineering, was proposed to control soil erosion and meliorate soil within the Pisha Sandstone area. To assess its effectiveness and the ecological restoration and soil improvement performance, a field experiment was conducted in this area. We found the strong sediment retention capacity of the SFD is the basis of using it to restore the ecosystem. We compared some certain ecological factors and soil quality between a gully with the SFD and a gully without the SFD, including soil moisture, soil organic matter (SOM), soil nutrients (including Ammonia Nitrogen, available phosphorus and Potassium), vegetation coverage and biodiversity. The results showed that the SFD exhibits excellent performance for ecological restoration and soil improvement of this area. The results are as follows: (i) by the sediment retention action, the deposition commonly occurred in the SFD gully, and the deposition patterns are obviously different from upper to lower gully, (ii) more surprisingly, unlike trees or other shrubs, the seabuckthorn has good horizontal extending capacity by its root system, (iii) soil moisture, SOM, soil nutrients, vegetation coverage and biodiversity in the vegetated gully with the SFD are all markedly increased. The results showed the SFD is both effective and novel biological measure for ecological restoration and soil improvement within the Pisha Sandstone area.

Yang, F. S.; Cao, M. M.; Li, H. E.; Wang, X. H.; Bi, C. F.

2014-09-01

344

Evaluation of transverse piezoelectric coefficient of ZnO thin films deposited on different flexible substrates: a comparative study on the vibration sensing performance.  

PubMed

We report on the systematic comparative study of highly c-axis oriented and crystalline piezoelectric ZnO thin films deposited on four different flexible substrates for vibration sensing application. The flexible substrates employed for present experimental study were namely a metal alloy (Phynox), metal (aluminum), polyimide (Kapton), and polyester (Mylar). ZnO thin films were deposited by an RF reactive magnetron sputtering technique. ZnO thin films of similar thicknesses of 700 ± 30 nm were deposited on four different flexible substrates to have proper comparative studies. The crystallinity, surface morphology, chemical composition, and roughness of ZnO thin films were evaluated by respective material characterization techniques. The transverse piezoelectric coefficient (d31) value for assessing the piezoelectric property of ZnO thin films on different flexible substrates was measured by a four-point bending method. ZnO thin films deposited on Phynox alloy substrate showed relatively better material characterization results and a higher piezoelectric d31 coefficient value as compared to ZnO films on metal and polymer substrates. In order to experimentally verify the above observations, vibration sensing studies were performed. As expected, the ZnO thin film deposited on Phynox alloy substrate showed better vibration sensing performance. It has generated the highest peak to peak output voltage amplitude of 256 mV as compared to that of aluminum (224 mV), Kapton (144 mV), and Mylar (46 mV). Therefore, metal alloy flexible substrate proves to be a more suitable, advantageous, and versatile choice for integrating ZnO thin films as compared to metal and polymer flexible substrates for vibration sensing applications. The present experimental study is extremely important and helpful for the selection of a suitable flexible substrate for various applications in the field of sensor and actuator technology. PMID:24773266

Joshi, Sudeep; Nayak, Manjunatha M; Rajanna, K

2014-05-28

345

Friction evaluation of concrete paver blocks for airport pavement applications  

NASA Technical Reports Server (NTRS)

The development and use of concrete paver blocks is reviewed and some general specifications for application of this type of pavement surface at airport facilities are given. Two different shapes of interlocking concrete paver blocks installed in the track surface at NASA Langley's Aircraft Landing Dynamics Facility (ALDF) are described. Preliminary cornering performance results from testing of 40 x 14 radial-belted and bias-ply aircraft tires are reviewed. These tire tests are part of a larger, ongoing joint NASA/FAA/Industry Surface Traction and Radial Tire (START) Program involving several different tire sizes. Both dry and wet surface conditions were evaluated on the two concrete paver block test surfaces and a conventional, nongrooved Portland cement concrete surface. Future test plans involving evaluation of other concrete paver block designs at the ALDF are indicated.

Yager, Thomas J.

1992-01-01

346

Flexible asymmetric supercapacitors based on ultrathin two-dimensional nanosheets with outstanding electrochemical performance and aesthetic property  

PubMed Central

Flexible asymmetric supercapacitors with excellent electrochemical performance and aesthetic property are realized by using ultrathin two-dimensional (2D) MnO2 and graphene nanosheets as cathode and anode materials, respectively. 2D MnO2 nanosheets (MSs) with a thickness of ca. 2?nm are synthesized with a soft template method for the first time, which achieve a high specific capacitance of 774?F g?1 even after 10000 cycles. Asymmetric supercapacitors based on ultrathin MSs and graphene exhibit a very high energy density up to 97.2?Wh kg?1 with no more than 3% capacitance loss after 10000 cycles in aqueous electrolyte. Most interestingly, we show that the energy storage device can have an aesthetic property. For instance, a “Chinese panda” supercapacitor is capable of lighting up a red light emitting diode. This work has another, quite different aspect that a supercapacitor is no longer a cold industry product, but could have the meaning of art. PMID:24008931

Shi, Shan; Xu, Chengjun; Yang, Cheng; Chen, Yanyi; Liu, Juanjuan; Kang, Feiyu

2013-01-01

347

High-performance large-scale flexible dye-sensitized solar cells based on anodic TiO2 nanotube arrays.  

PubMed

A simple strategy to fabricate flexible dye-sensitized solar cells involves the use of photoanodes based on TiO2 nanotube (TNT) arrays with rear illumination. The TNT films (tube length ?35 ?m) were produced via anodization, and sensitized with N719 dye for photovoltaic characterization. Pt counter electrodes of two types were used: a conventional FTO/glass substrate for a device of rigid type and an ITO/PEN substrate for a device of flexible type. These DSSC devices were fabricated into either a single-cell structure (active area 3.6×0.5 cm2) or a parallel module containing three single cells (total active area 5.4 cm2). The flexible devices exhibit remarkable performance with efficiencies ?=5.40% (single cell) and 4.77% (parallel module) of power conversion, which outperformed their rigid counterparts with ?=4.87% (single cell) and 4.50% (parallel model) under standard one-sun irradiation. The flexible device had a greater efficiency of conversion of incident photons to current and a broader spectral range than the rigid device; a thinner electrolyte layer for the flexible device than for the rigid device is a key factor to improve the light-harvesting ability for the TNT-DSSC device with rear illumination. Measurements of electrochemical impedance spectra show excellent catalytic activity and superior diffusion characteristics for the flexible device. This technique thus provides a new option to construct flexible photovoltaic devices with large-scale, light-weight, and cost-effective advantages for imminent applications in consumer electronics. PMID:24050628

Jen, Hsiu-Ping; Lin, Meng-Hung; Li, Lu-Lin; Wu, Hui-Ping; Huang, Wei-Kai; Cheng, Po-Jen; Diau, Eric Wei-Guang

2013-10-23

348

Permeable Pavement Demonstration at the Edison Environmental Center (Hartford)  

EPA Science Inventory

In general, there is a lack of full-scale, outdoor, real-world porous pavement studies with system replicates. More studies of porous pavement operating in its intended use (parking lot, roadway, etc.) with climatic events, regular use, and maintenance effects, are necessary. The...

349

Permeable pavement demonstration at the Edison Environmental Center (Hartford, CT)  

EPA Science Inventory

In general, there is a lack of full-scale, outdoor, real-world porous pavement studies with system replicates. More studies of porous pavement operating in its intended use (parking lot, roadway, etc.) with climatic events, regular use, and maintenance effects, are necessary. The...

350

Permeable Pavement Monitoring at the Edison Environmental Center Demonstration Site  

EPA Science Inventory

There are few detailed studies of full-scale, replicated, actively-used pervious pavement systems. Practitioners need additional studies of pervious pavement systems in its intended application (parking lot, roadway, etc.) during a range of climatic events, daily usage conditions...

351

Permeable pavement monitoring at the Edison Environmental Center demonstration site  

EPA Science Inventory

There are few detailed studies of full-scale, replicated, actively-used pervious pavement systems. Practitioners need additional studies of pervious pavement systems in its intended application (parking lot, roadway, etc.) during a range of climatic events, daily usage conditions...

352

Portland Cement Concrete Pavement Shannon Golden, Alabama DOT  

E-print Network

Portland Cement Concrete Pavement Shannon Golden, Alabama DOT PORTLAND CEMENT CONCRETE PAVEMENT may be substituted for part of the required Portland cement. Substitution of mineral admixtures shall Cement shall not exceed the percentages shown in the following table: MAXIMUM ALLOWABLE SUBSTITUTION

353

Guide to Cement-Based Integrated Pavement Solutions  

E-print Network

Guide to Cement-Based Integrated Pavement Solutions August 2011 #12;Cement-Based Integrated Commercial Residential Recreation LAND USE CEMENT-BASED INTEGRATED PAVEMENT SOLUTIONS 1 2 3 4 5 6 7 8 Conventional Overlays CRCP VIBRATORY COMPACTION Pervious Concrete Full-Depth Reclamation Cement- Treat- ed Base

354

Energy equivalents for selected pavement materials: Their production and placement  

NASA Astrophysics Data System (ADS)

Energy requirements for selected pavement surfaces are discussed. Energy requirements for hot-mixed bituminous recycling and portland cement concrete recycling projects are presented along with conventional pavement methods. Energy requirements for conventional thin surface treatments are also discussed. Environmental analyses involving both air and noise quality measurement are included for various recycling and conventional paving options.

Lane, K. R.

1981-03-01

355

Experimental study on properties of pervious concrete pavement materials  

Microsoft Academic Search

In this paper, a pervious concrete pavement material used for roadway is introduced. Using the common material and method, the strength of the pervious concrete is low. Using smaller sized aggregate, silica fume (SF), and superplasticizer (SP) in the pervious concrete can enhance the strength of pervious concrete greatly. The pervious pavement materials that composed of a surface layer and

Jing Yang; Guoliang Jiang

2003-01-01

356

211. EQUIPMENT LAYING FIRST LANE OF CONCRETE PAVEMENT NEAR THE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

211. EQUIPMENT LAYING FIRST LANE OF CONCRETE PAVEMENT NEAR THE CAPITAL OVERLOOK, 1931. NOTE THE BEGINNING OF BITUMINOUS TYPE OF TEMPORARY PAVEMENT TO ALLOW FOR SETTLEMENT IN HYDRAULIC FILL AREAS. - George Washington Memorial Parkway, Along Potomac River from McLean to Mount Vernon, VA, Mount Vernon, Fairfax County, VA

357

Airport pavement management systems: an appraisal of existing methodologies  

Microsoft Academic Search

Airport pavement management systems (APMS) are computer-based decision support systems that can be used by the agencies running airports to determine cost-effective maintenance and rehabilitation strategies to preserve the various pavement structures (runways, taxiways, etc.) which are a critical component of these facilities. In this paper, we describe the main elements of APMS and review existing systems.

Michel Gendreau; Patrick Soriano

1998-01-01

358

Fracture resistance characterization of chemically modified crumb rubber asphalt pavement  

Microsoft Academic Search

The fracture resistance of chemically modified crumb rubber asphalt (CMCRA) pavement was evaluated based on the J-integral concept. The chemical modification process used was developed by the Federal Highway Administration and patented in 1998. The results were compared to that of crumb rubber asphalt (CRA) and control asphalt pavement. Four semi-circular core specimens (76 mm radius and 57 mm thickness)

M. A. Mull; K. Stuart; A. Yehia

2002-01-01

359

Permeable pavement demonstration site at Edison Environmental Center (Presentation)  

EPA Science Inventory

There are few studies of full-scale, outdoor, replicated, working pervious pavement systems. More studies of pervious pavement operating in its intended use (parking lot, roadway, etc.) during a range of climatic events, daily usage conditions, and maintenance regimes are necessa...

360

Permeable pavement demonstration at the Edison Environmental Center  

EPA Science Inventory

There are few studies of full-scale, outdoor, replicated, functioning pervious pavement systems. More studies of pervious pavement operating in its intended use (parking lot, roadway, etc.) during a range of climatic events, daily usage conditions, and maintenance regimes are nec...

361

Permeable Pavement Research at the Edison Environmental Center  

EPA Science Inventory

There are few detailed studies of full-scale, replicated, actively-used permeable pavement systems. Practitioners need additional studies of permeable pavement systems in its intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage conditio...

362

Full-Depth Asphalt Pavements for Parking Lots and Driveways.  

ERIC Educational Resources Information Center

The latest information for designing full-depth asphalt pavements for parking lots and driveways is covered in relationship to the continued increase in vehicle registration. It is based on The Asphalt Institute's Thickness Design Manual, Series No. 1 (MS-1), Seventh Edition, which covers all aspects of asphalt pavement thickness design in detail,…

Asphalt Inst., College Park, MD.

363

Project Information Form Project Title White Paper on The application of permeable pavement with emphasis  

E-print Network

Project Information Form Project Title White Paper on The application of permeable pavement Project Depending on the type of surface pavement, permeable pavement can be termed as porous asphalt and improve water quality as well as urban heat island, the application of permeable pavement in urban areas

California at Davis, University of

364

Flexible Acculturation  

E-print Network

-state and family — are relatively insufficient. In this paper, I explore the concept of “flexible acculturation,” first proposed by Jan Nederveen-Pieterse (2007), to show a cultural aspect of transnational flexibility. I situate my discussion in the literature...

Lee, Hsiang-Chieh

2008-01-01

365

Clogging evaluation of open graded friction course pavements tested under rainfall and heavy vehicle simulators.  

PubMed

In this study a new procedure is developed to obtain core samples from field sections to assess clogging mechanisms of open graded friction course (OGFC) pavements using X-ray computed tomography (CT) imaging. The approach compared X-ray computed tomography (CT) images taken before and after: (1) rainfall simulations without trafficking to investigate particle-related clogging and (2) full-scale accelerated pavement rutting tests (APT) to investigate deformation related clogging of OGFC layers. Rainfall simulations were performed with runoff water of known total suspended solids (TSS) and particle size distributions (PSDs). Full-scale accelerated rutting tests were performed under controlled temperature and loads. Both investigations were performed for three different OGFC pavements with different layer thicknesses and mix types. The clogging of rutting test sections were also evaluated by comparing the surface permeability measurements performed before and after APT testing. The results of X-ray CT image processing revealed a significant reduction in air-void content of core samples after APT rutting tests. The highest air-void reduction was concentrated at the bottom of the OGFC layers. Permeability measurements also showed a 40%-90% reduction in permeability after APT trafficking. X-ray CT image processing of core samples tested under simulated rainfall showed that air void content reduction is concentrated in the lower part (2-6 mm from the bottom) of the OGFC layers as a result of particle accumulation. Small changes in air void contents were observed in the upper part of the OGFC layers (10-15 mm) while these reductions in air void contents were not significant to cause surface overflow and hence it is expected that the tested OGFC pavements will have sufficient permeability to infiltrate water during most average storm events. PMID:23920417

Coleri, Erdem; Kayhanian, Masoud; Harvey, John T; Yang, Kai; Boone, John M

2013-11-15

366

New structural systems for zero-maintenance pavements. Volume 3: Anchored pavement system designed for Edens Expressway  

Microsoft Academic Search

The response of the Edens Expressway subjected to mechanical and environmental loads using the anchored pavement concept is discussed. The mechanical and thermal properties of materials that could be encountered in future reconstruction of Edens Expressway are presented in a consistent form for computer programming. These properties are viewed as typical design values during investigation of pavement response. The behavior

S. K. Saxena; S. G. Militsopoulos

1980-01-01

367

Effectiveness of low impact development practices in two urbanized watersheds: retrofitting with rain barrel/cistern and porous pavement.  

PubMed

The impacts of urbanization on hydrology and water quality can be minimized with the use of low impact development (LID) practices in urban areas. This study assessed the performance of rain barrel/cistern and porous pavement as retrofitting technologies in two urbanized watersheds of 70 and 40 km(2) near Indianapolis, Indiana. Six scenarios consisting of the watershed existing condition, 25% and 50% implementation of rain barrel/cistern and porous pavement, and 25% rain barrel/cistern combined with 25% porous pavement were evaluated using a proposed LID modeling framework and the Long-Term Hydrologic Impact Assessment (L-THIA)-LID model. The model was calibrated for annual runoff from 1991 to 2000, and validated from 2001 to 2010 for the two watersheds. For the calibration period, R(2) and NSE values were greater than 0.60 and 0.50 for annual runoff and streamflow. Baseflow was not calibrated in this study. During the validation period, R(2) and NSE values were greater than 0.50 for runoff and streamflow, and 0.30 for baseflow in the two watersheds. The various application levels of barrel/cistern and porous pavement resulted in 2-12% reduction in runoff and pollutant loads for the two watersheds. Baseflow loads slightly increased with increase in baseflow by more than 1%. However, reduction in runoff led to reduction in total streamflow and associated pollutant loads by 1-9% in the watersheds. The results also indicate that the application of 50% rain barrel/cistern, 50% porous pavement and 25% rain barrel/cistern combined with 25% porous pavement are good retrofitting options in these watersheds. The L-THIA-LID model can be used to inform management and decision-making for implementation of LID practices at the watershed scale. PMID:23474339

Ahiablame, Laurent M; Engel, Bernard A; Chaubey, Indrajeet

2013-04-15

368

Geotextiles, one among the different geosynthetic products, can be used for a number of functions or applications in pavement design. Specifically, woven or nonwoven geotextiles have been used in pavements to fulfill the  

E-print Network

or applications in pavement design. Specifically, woven or nonwoven geotextiles have been used in pavements of geotextile and its location within the pavement system. The benefits of using geotextiles in pavements for more cost-effective pavements are probably being missed by not using (or by incorrectly using

Zornberg, Jorge G.

369

Adaptive road crack detection system by pavement classification.  

PubMed

This paper presents a road distress detection system involving the phases needed to properly deal with fully automatic road distress assessment. A vehicle equipped with line scan cameras, laser illumination and acquisition HW-SW is used to storage the digital images that will be further processed to identify road cracks. Pre-processing is firstly carried out to both smooth the texture and enhance the linear features. Non-crack features detection is then applied to mask areas of the images with joints, sealed cracks and white painting, that usually generate false positive cracking. A seed-based approach is proposed to deal with road crack detection, combining Multiple Directional Non-Minimum Suppression (MDNMS) with a symmetry check. Seeds are linked by computing the paths with the lowest cost that meet the symmetry restrictions. The whole detection process involves the use of several parameters. A correct setting becomes essential to get optimal results without manual intervention. A fully automatic approach by means of a linear SVM-based classifier ensemble able to distinguish between up to 10 different types of pavement that appear in the Spanish roads is proposed. The optimal feature vector includes different texture-based features. The parameters are then tuned depending on the output provided by the classifier. Regarding non-crack features detection, results show that the introduction of such module reduces the impact of false positives due to non-crack features up to a factor of 2. In addition, the observed performance of the crack detection system is significantly boosted by adapting the parameters to the type of pavement. PMID:22163717

Gavilán, Miguel; Balcones, David; Marcos, Oscar; Llorca, David F; Sotelo, Miguel A; Parra, Ignacio; Ocaña, Manuel; Aliseda, Pedro; Yarza, Pedro; Amírola, Alejandro

2011-01-01

370

Tire Footprint Affects Hydroplaning On Wet Pavement  

NASA Technical Reports Server (NTRS)

Recent investigations of tire hydroplaning at highway speeds reveal, in addition to inflation pressure, tire-footprint aspect ratio (FAR), defined as width divided by length of tire surface in contact with pavement, significantly influences speed at which dynamic hydroplaning begins. Tire speeds and forces developed during tests of up to 65 mi/h (105 km/h) were monitored on flooded test surface to identify development of hydroplaning. Study focused on automotive tires because FAR's of automotive tires vary more than those of aircraft tires.

Yager, Thomas J.

1989-01-01

371

High-performance plastic platinized counter electrode via photoplatinization technique for flexible dye-sensitized solar cells.  

PubMed

A photoplatinization technique was proposed to deposit Pt on a thin TiO(2) layer modified indium tin oxide-coated polyethylene naphthalate (ITO/PEN) substrate at low temperature (about 50 °C after 1 h of UV irradiation) for the first time. The fabrication process includes coating and hydrolyzing the tetra-n-butyl titanate to form a TiO(2)-modified layer and the photoplatinization of the modified substrate in H(2)PtCl(6)/2-propanol precursor solution under UV irradiation. The obtained platinized electrodes were used as counter electrodes (CE) for flexible dye-sensitized solar cells (FDSCs). The well-optimized platinized electrode showed high optical transmittance, up to 76.5% between 400 and 800 nm (T(av)), and the charge transfer resistance (R(ct)) was as low as 0.66 ? cm(2). A series of characterizations also demonstrated the outstanding chemical/electrochemical durability and mechanical stability of the platinized electrode. The FDSCs with TiO(2)/Ti photoanodes and the obtained CEs achieved a power conversion efficiency (PCE) up to 8.12% under rear-side irradiation (AM 1.5 illumination, 100 mW cm(-2)). The obtained CEs were also employed in all-plastic bifacial DSCs. When irradiated from the rear side, the bifacial FDSC yielded a PCE of 6.26%, which approached 90% that of front-side irradiation (6.97%). Our study revealed that, apart from serving as a functional layer for deposition of Pt, the thin TiO(2) layer modification on ITO/PEN substrates also played an important role in improving the transparency and the mechanical properties of the CE. The effect of the thickness of the TiO(2) layer for Pt coating on the performance of the CE was also investigated. PMID:23039879

Fu, Nian-Qing; Fang, Yan-Yan; Duan, Yan-Dong; Zhou, Xiao-Wen; Xiao, Xu-Rui; Lin, Yuan

2012-11-27

372

Use of shredded tires in the subbase layer of asphalt pavements  

SciTech Connect

Research was conducted on the use of shredded scrap tires for use in the subbase layer of asphalt pavements. Mixtures of shredded scrap tires with virgin soil provide a means of recycling unwanted tires and conserving a finite supply of virgin soil. The mechanistic procedure for the design of pavement systems requires resilient modulus values. Plastic and elastic strains were measured using external LVDT`s and internal proximity sensors. Resilient modulus measurements were conducted on cohesionless soils mixed with various amounts of shredded tire chips. The performance f the shredded tire mixture is compared to that of the naturally occurring virgin soil used in subbase applications in New Jersey. A number of experimental issues are discussed such as: method of compaction, optimum ratio of shredded tire chips to soil, optimum size and gradation of shredded tire chips, and strength testing using California Bearing Ratio.

Papp, W.J. Jr.; Maher, M.H. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Civil and Environmental Engineering; Baker, R.F. [New Jersey Dept. of Transportation, Trenton, NJ (United States)

1997-12-31

373

Recycling crumb rubber modified asphalt pavements (revised). Final research report, September 1992-August 1994  

SciTech Connect

There has been concern that the legislative mandate to use waste rubber in paving applications will result in a severe environmental problem when it becomes necessary to recycle these pavements. If successful recycling is possible, the long term performance of these pavements becomes a concern. The results of this study indicate that it is possible to recycle this material. However, some techniques for conventional asphalt mixture design, material processing, and construction must be modified to ensure this success, and some techniques may not be appropriate when waste rubber is present in the mixture to be recycled. Many of the results presented in this study are based on experiences in Tyler and San Antonio, Texas, where two of the earliest crumb rubber recycling operations in the United States have transpired.

Crockford, W.W.; Makunike, D.; Davison, R.R.; Scullion, T.; Billiter, T.C.

1995-07-01

374

Runoff and infiltration characteristics of pavement structures--review of an extensive monitoring program.  

PubMed

The stormwater runoff and infiltration performance of permeable pavements has been systematically evaluated within an intensive monitoring program. The primary objective of the investigation was to generate a broad database, which enables the development of an advanced simulation module for urban drainage modelling. Over 160 field and lab scale experiments have been completed and analyzed for surface runoff and infiltration characteristics. The test series include several pavement types under various boundary conditions such as diverse precipitation impacts, varying surface slope and layer construction as well as different stages of surface clogging and several base and subgrade layer characteristics. The results represent a reliable and comprehensive database that allows profound conclusions and substantial recommendations. PMID:18048986

Illgen, M; Harting, K; Schmitt, T G; Welker, A

2007-01-01

375

A review on using crumb rubber in reinforcement of asphalt pavement.  

PubMed

An immense problem affecting environmental pollution is the increase of waste tyre vehicles. In an attempt to decrease the magnitude of this issue, crumb rubber modifier (CRM) obtained from waste tyre rubber has gained interest in asphalt reinforcement. The use of crumb rubber in the reinforcement of asphalt is considered as a smart solution for sustainable development by reusing waste materials, and it is believed that crumb rubber modifier (CRM) could be an alternative polymer material in improving hot mix asphalt performance properties. In this paper, a critical review on the use of crumb rubber in reinforcement of asphalt pavement will be presented and discussed. It will also include a review on the effects of CRM on the stiffness, rutting, and fatigue resistance of road pavement construction. PMID:24688369

Mashaan, Nuha Salim; Ali, Asim Hassan; Karim, Mohamed Rehan; Abdelaziz, Mahrez

2014-01-01

376

A Review on Using Crumb Rubber in Reinforcement of Asphalt Pavement  

PubMed Central

An immense problem affecting environmental pollution is the increase of waste tyre vehicles. In an attempt to decrease the magnitude of this issue, crumb rubber modifier (CRM) obtained from waste tyre rubber has gained interest in asphalt reinforcement. The use of crumb rubber in the reinforcement of asphalt is considered as a smart solution for sustainable development by reusing waste materials, and it is believed that crumb rubber modifier (CRM) could be an alternative polymer material in improving hot mix asphalt performance properties. In this paper, a critical review on the use of crumb rubber in reinforcement of asphalt pavement will be presented and discussed. It will also include a review on the effects of CRM on the stiffness, rutting, and fatigue resistance of road pavement construction. PMID:24688369

Mashaan, Nuha Salim; Ali, Asim Hassan; Karim, Mohamed Rehan; Abdelaziz, Mahrez

2014-01-01

377

Flexible binder-free metal fibril mat-supported silicon anode for high-performance lithium-ion batteries.  

PubMed

We report the fabrication of a flexible and binder-free metal fibril mat-supported Si anode (Si@SFM) by a simple process. The fabricated Si@SFM anode showed a high discharge capacity, ?3000 mAh g(-1) at a current rate of 300 mA g(-1), and exhibited stable capacity retention, 90% at a 1 C rate (2000 mA g(-1)) after 200 cycles. The rate capability of the electrode was still high even when both the charge and the discharge current rates were markedly increased at the same time (1234 mAh g(-1) for charge-discharge time of ?12 min). Moreover, owing to its mechanical flexibility, the Si@SFM can be adopted as a key component of flexible lithium-ion batteries (LIBs). After cell packaging, the rechargeable flexible battery under bending stress showed only a little capacity fading (86% of initial capacity) at 1000 mA g(-1) over 150 cycles. These results suggest that the Si@SFM electrode is readily suitable for use in rechargeable flexible LIBs. PMID:25020188

Song, Seonghyun; Kim, Sang Woo; Lee, Dong Jin; Lee, Young-Gi; Kim, Kwang Man; Kim, Chang-Hyeon; Park, Jung-Ki; Lee, Yong Min; Cho, Kuk Young

2014-07-23

378

Joint application of GPR and electrostatic resistivity to assess mixed pavement condition  

NASA Astrophysics Data System (ADS)

In planning maintenance and rehabilitation of paved streets it is of first importance to gather internal structure information to establish a diagnostic. We investigate the potential of the GPR and of the capacitively-coupled resistivity array profiling techniques to map the geometry and the defects present at various depths in streets with mixed pavement. GPR is excellent at delineating boundaries of material with contrasting electrical properties whereas the resistivity array is needed to determine the nature and quality of the imaged material. Thicknesses of asphalt and concrete can be continuously determined. Defects such as cracks, delaminations, voids and former repairs can be mapped. Quality of the concrete slab can be assessed by resistivity. The performances of the two techniques are demonstrated first using numerical modeling and imaging of typical pavement defects. Resistivity and GPR data were collected along a few streets in Montreal using a 1GHz GPR smart cart and a compact 2-receiver dipole resistivity system. Streets were selected to demonstrate the responses to different pavement defects. The results allow to show the performance and limitations of present systems. In particular, it is shown that multiple configuration arrays and real-time imaging for the resistivity pulled array are needed. For the arrays we investigate some designs and for the real-time imaging a technique based on Kalman filtering was developed.

Chouteau, M.; Camerlynck, C.; Kaouane, C.

2009-05-01

379

Insights into mechanical compression and the enhancement in performance by Mg(OH)2 coating in flexible dye sensitized solar cells.  

PubMed

The engineering of flexible dye sensitized solar cells (DSCs) by mechanical compression is one of the methods that allow low temperature processing of these devices. However, suppressing the high temperature sintering process also significantly reduces the performance of the cells. In our previous work [J. Phys. Chem. C, 2012, 116, 1211], we have attempted to improve flexible DSC performance by coating the porous TiO2 photoanode with an electrodeposited Mg(OH)2 layer. In that work, we have obtained one of the highest photovoltages reported to date in flexible DSCs (847 mV). In order to gain more insights into the reasons for both poorer performance of compressed cells and the origin of the voltage enhancement achieved by the Mg(OH)2 coating, here we present an in-depth study by means of electrochemical impedance spectroscopy, Mott-Schottky plots analysis and open-circuit voltage decays. The existence of a shunt resistance in the mechanically compressed cells is revealed, causing an additional drawback to the poor inter-particle necking. By introducing the Mg(OH)2 coating the recombination in the cell becomes significantly reduced, being the key reason which is responsible for the higher photovoltage. Additionally, the coating and the compression cause modifications in the surface states and in the nature of the interfaces with the electrolyte. This induces TiO2 conduction band displacements and shifts of the relative position of the modified states that influence the performance. PMID:24424329

Peiris, T A Nirmal; Wijayantha, K G Upul; García-Cañadas, Jorge

2014-02-21

380

Asphalt Pavement Aging and TemperatureAsphalt Pavement Aging and Temperature Dependent Properties using a FunctionallyDependent Properties using a Functionally  

E-print Network

Asphalt Pavement Aging and TemperatureAsphalt Pavement Aging and Temperature Dependent Properties(132) 3 #12;Functionally Graded Viscoelastic AsphaltFunctionally Graded Viscoelastic Asphalt Concrete ModelConcrete Model Motivation and Introduction Viscoelastic Characterization of Asphalt Concrete

Paulino, Glaucio H.

381

Effects of pavement surface characteristics and textures on skid resistance  

E-print Network

to the pavement suriace between parallel lines of nmsking tape and then worked into the surface voids with an aluminum squeeoee faced neith a rubber pad having a hardness approxi- mately equivalent to that of a tire tread rubber. An average tex- ture depth... particles m?ch like a tire tread element. Hater is poured into the cylinder, and the time required for a known volume of water to es- cape through any pores in the pavement and between the rubber ring and the pavement surface is measured. The water...

Tomita, Hisao

1970-01-01

382

Design of a flexible high performance quadcopter platform breaking the MAV endurance record with laser power beaming  

Microsoft Academic Search

In this paper we present the design of a highly flexible quadcopter platform and the software tools used in an example experiment to show unlimited flight time of an MAV with laser power beaming. We describe the mechanical design as well as the flight control system architecture which are focused on easy adaption to a wide variety of experiments. The

Michael C. Achtelik; Jan Stumpf; Daniel Gurdan; Klaus-Michael Doth

2011-01-01

383

Advance mathematical model to study and analyse the effects of total quality management (TQM) and operational flexibility on hospital performance  

Microsoft Academic Search

Total quality management (TQM) and operational flexibility are powerful and evolving management tools that are being implemented in many organisations worldwide, particularly in healthcare services. However, such implementation is yet to be seen in developing nations, particularly in health care. In an attempted response to such a gap, this paper provides a literature review on the principles and scope of

Main Naser Fady Alolayyan; Khairul Anuar Mohd Ali; Fazli Idris; Ahmmed Saadi Ibrehem

2011-01-01

384

Laser scanning on road pavements: a new approach for characterizing surface texture.  

PubMed

The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the "texture" appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experiment on the use of laser scanner techniques on various types of asphalt for texture characterization. The use of high precision laser scanners, such as the triangulation types, is proposed to expand the analysis of road pavement from the commonly and currently used two-dimensional method to a three-dimensional one, with the aim of extending the range of the most important parameters for these kinds of applications. Laser scanners can be used in an innovative way to obtain information on areal surface layer through a single measurement, with data homogeneity and representativeness. The described experience highlights how the laser scanner is used for both laboratory experiments and tests in situ, with a particular attention paid to factors that could potentially affect the survey. PMID:23012535

Bitelli, Gabriele; Simone, Andrea; Girardi, Fabrizio; Lantieri, Claudio

2012-01-01

385

Laser Scanning on Road Pavements: A New Approach for Characterizing Surface Texture  

PubMed Central

The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the “texture” appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experiment on the use of laser scanner techniques on various types of asphalt for texture characterization. The use of high precision laser scanners, such as the triangulation types, is proposed to expand the analysis of road pavement from the commonly and currently used two-dimensional method to a three-dimensional one, with the aim of extending the range of the most important parameters for these kinds of applications. Laser scanners can be used in an innovative way to obtain information on areal surface layer through a single measurement, with data homogeneity and representativeness. The described experience highlights how the laser scanner is used for both laboratory experiments and tests in situ, with a particular attention paid to factors that could potentially affect the survey. PMID:23012535

Bitelli, Gabriele; Simone, Andrea; Girardi, Fabrizio; Lantieri, Claudio

2012-01-01

386

Leaching of heavy metals and polycyclic aromatic hydrocarbons from reclaimed asphalt pavement.  

PubMed

The work presented herein displays the results of a study addressing environmental concerns related to the possible leaching of pollutants from reclaimed asphalt pavement. Samples from an experimental site were tested in both static batch tests and column leaching tests. Selected heavy metals and polycyclic aromatic hydrocarbons (PAHs) were analysed in leachates. The results have allowed us to consider the leaching of pollutants to be rather weak for most of the parameters studied. Concentrations in solutions from batch leaching tests were generally below the EC limit values for drinking water. Pollutant concentrations from column experiments were higher in solutions as of the initial leaching stages, but then decreased rapidly and wound up at values below the detection limits. The factors influencing results proved to be the material grain size and the percolation water flow rate. Results from leaching experiments performed on core samples taken on two rebuilt road section pavements, containing 10% and 20% of reclaimed asphalt pavement, respectively, confirmed the results obtained from the batch and column experiments. PMID:16083938

Legret, M; Odie, L; Demare, D; Jullien, A

2005-09-01

387

Pattern recognition algorithms for density estimation of asphalt pavement during compaction: a simulation study  

NASA Astrophysics Data System (ADS)

This paper presents the application of artificial neural network (ANN) based pattern recognition to extract the density information of asphalt pavement from simulated ground penetrating radar (GPR) signals. This study is part of research efforts into the application of GPR to monitor asphalt pavement density during compaction. The main challenge is to eliminate the effect of roller-sprayed water on GPR signals during compaction and to extract density information accurately. A calibration of the excitation function was conducted to provide an accurate match between the simulated signal and the real signal. A modified electromagnetic mixing model was then used to calculate the dielectric constant of asphalt mixture with water. A large database of GPR responses was generated from pavement models having different air void contents and various surface moisture contents using finite-difference time-domain simulation. Feature extraction was performed to extract density-related features from the simulated GPR responses. Air void contents were divided into five classes representing different compaction statuses. An ANN-based pattern recognition system was trained using the extracted features as inputs and air void content classes as target outputs. Accuracy of the system was tested using test data set. Classification of air void contents using the developed algorithm is found to be highly accurate, which indicates effectiveness of this method to predict asphalt concrete density.

Shangguan, Pengcheng; Al-Qadi, Imad L.; Lahouar, Samer

2014-08-01

388

New structural systems for zero-maintenance pavements. Volume 3: Anchored pavement system designed for Edens Expressway  

NASA Astrophysics Data System (ADS)

The response of the Edens Expressway subjected to mechanical and environmental loads using the anchored pavement concept is discussed. The mechanical and thermal properties of materials that could be encountered in future reconstruction of Edens Expressway are presented in a consistent form for computer programming. These properties are viewed as typical design values during investigation of pavement response. The behavior of the anchored pavement under induced temperature loads and weakening of subgrade (by thawing action) is clearly demonstrated. The example problem provides the input parameters of materials and loads for the analysis, the generation of finite element mesh, and the results of the analysis.

Saxena, S. K.; Militsopoulos, S. G.

1980-08-01

389

Roswell International Air Center Airport (ROW) Pavement Condition and Analysis  

E-print Network

Roswell International Air Center Airport (ROW) Pavement Condition and Analysis Submitted to: Jane M ................................................1. Conditions at Roswell International Air Center (ROW) 4 .................................Figure 1. Geographic Location of Roswell International Air Center (ROW) 4 ..............................Table 1

Cal, Mark P.

390

Raton Municipal Airport (RTN) Pavement Condition and Analysis  

E-print Network

Raton Municipal Airport (RTN) Pavement Condition and Analysis Submitted to: Jane M. Lucero, AICP ...............................................................1. Conditions at Raton Municipal Airport (RTN) 4 ................................................Figure 1. Geographic Location of Raton Municipal Airport (RTN) 4

Cal, Mark P.

391

Life cycle assessment of concrete pavements : impacts and opportunities  

E-print Network

The concrete pavement network in the United States plays a crucial role in the economy by enabling the transport of people and goods, but it also leads to resource consumption and environmental impacts. This thesis is ...

Loijos, Alex (Alexander Nikos)

2011-01-01

392

Nondestructive evaluation of load transfer at rigid airport pavement joints  

NASA Astrophysics Data System (ADS)

Current design criteria for rigid pavements for commercial and military airfields assume that 25% of the load applied to an edge of a slab is transferred through the joint to an adjacent unloaded slab. A nondestructive testing technique using a falling weight deflectometer (FWD) was used to conduct field testing at a number of sites. A transfer function, developed from an analytical study, was used to estimate load transfer from the measured joint efficiency as a function of the loaded area and the radius of relative stiffness of the pavement. This procedure, although analytically sound, lacks actual field verification at an instrumented pavement site. This procedure was used to estimate load transfer at a number of commercial and military airfields for a variety of joint types, climate conditions, and pavement structures. The results of these tests indicate that the assumption of load transfer as a constant value of 25% appears to be unconservative, especially during the winter months.

Hammons, Michael I.

1995-07-01

393

Complex Modulus Prediction of Asphalt Concrete Pavement Cores  

E-print Network

. For field cores complex modulus measuring methods, except some expensive pavement field testers, empirical and semiempirical models are widely used, but an accurate mechanical test method is more desired. In this research, Arizona, Yellowstone National Park...

Ling, Meng

2013-12-02

394

Automated crack control analysis for concrete pavement construction  

E-print Network

probabilistic approach to determine the optimum time and depth of sawcutting for newly constructed portland cement concrete pavements. Variability in climate conditions and material characteristics during the hardening process affects the potential of cracking...

Jang, Se Hoon

2005-11-01

395

Flexibility Program  

ERIC Educational Resources Information Center

These brief guidelines for a muscular flexibility program state that the purpose of such a program is to increase the range of motion in order to avoid injuries and eliminate awkwardness in physical activities. A flexibility program is described as an extension of the warm-up period and should be an ongoing, permanent effort to lengthen muscles. A…

Connors, G. Patrick

396

Recycled materials in asphalt pavements. (Latest citations from the NTIS bibliographic database). Published Search  

SciTech Connect

The bibliography contains citations concerning the recycling of asphalt pavement materials, and the use of other recycled materials to manufacture asphalt pavement. Articles discuss methods used for recycling bituminous pavement including hot-mix and cold-mix. Materials used to improve recycled pavement, and recycled materials used in asphalt pavement include latexes, rubber scrap such as tires, glass shards, concretes, dusts, waste oils, roofing wastes, sulfur, and metal refining sludges. Testing and evaluation of recycled pavements both in laboratories and in test cases are considered. (Contains a minimum of 160 citations and includes a subject term index and title list.)

Not Available

1994-05-01

397

Gantry robot with extended workspace for pavement sign painting operations  

Microsoft Academic Search

The current method for pavement sign marking operations is labor-intensive and very dangerous due to the exposure of workers\\u000a to passing traffic. It also requires blocking traffic for a long period of time resulting serious traffic jam. This paper\\u000a deals with the development of a robotic system for automating the pavement sign painting operations. The robotic system consists\\u000a of gantry

Daehie Hong; Woo-Chang Lee; Baeksuk Chu; Tae-Hyung Kim; Woo Chun Choi

2005-01-01

398

Preventive Maintenance Condition Standards of Expressway Asphalt Pavement  

Microsoft Academic Search

There isn't a unified pavement preventive maintenance road condition standard both at home and abroad till now, in view of that, macro and micro road condition standard for expressway asphalt pavement preventive maintenance is established, among which macro standard is under the promise of PSSIges83, and is under the control standard of 82lesPCI<88, 88lesRQI<93, 85lesSRI<90. Its determinative process, the usage

Hu Guoxiang; Li Jie

2009-01-01

399

Tolerable Strains for HMA Overlays over Concrete Pavements  

E-print Network

Tolerable Strains for HMA Overlays over Concrete Pavements By Ashwani Gautam Submitted to the graduate degree program in Civil Engineering and the Graduate Faculty of the University of Kansas School of Engineering in partial fulfillment.../23/09 ii The Thesis Committee for Ashwani Gautam certifies That this is the approved version of the following thesis: Tolerable Strains for HMA Overlays over Concrete Pavements Committee: _______________________ Dr. Jie Han, Chairperson...

Gautam, Ashwani

2009-06-10

400

Rehabilitation of continuously reinforced concrete pavements using overlays  

E-print Network

REHABILITATION OF CONTINUOUSLY REINFORCED CONCRETE PAVEMENTS USING OVERLAYS A Thesis by SOUMYA SRIRAMAN Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE... August 1993 Major Subject: Civil Engineering REHABILITATION OF CONTINUOUSLY REINFORCED CONCRETE PAVEMENTS USING OVERLAYS A Thesis by SOUMYA SRIRAMAN Submitted to Texas A&M University in partial fulfillment of the requirements for the degree...

Sriraman, Soumya

1993-01-01

401

Pavement rehabilitation and funds allocation for a transportation network  

E-print Network

Function of Current Serviceability Index. . . . . . . . . . . 47 16 Gain in PES Components for the Various Maintenance Strategies. . . . . . . . . . 17 Minimum Acceptable PES (PSM). 18 Recommended Minimum Allowable Time (TMINI ) Until Next Application... Mix Pavement, Normal Traffic Load. 92 17 Rehabilitation Cycle for Hot Mix Pavement, Double Traffic Load 93 18 Rehabilitation Cycle for Overlays, Half Traffic Load 94 19 Rehabilitation Cycle for Overlays, Normal Traffic Load 95 LIST OF FIGURES...

Stein, Alvaro

2012-06-07

402

GPR abilities in investigation of the pavement transversal cracks  

NASA Astrophysics Data System (ADS)

This paper describes the results of an investigation into the capabilities of the GPR technique within the field of pavement crack diagnostics. Initially, laboratory tests were performed on prototypes simulating idealized cracks. Next, long-term visual observation and repeated GPR scanning were performed, on three roads of semi-rigid construction, several hundreds of meters long and subjected to heavy traffic. Furthermore, a road of rigid construction was tested, having a more than 70-year history of use. In several cases the cracks were probed by drillings, in order to recognize structures responsible for signal generation, or to explain reasons of signal lacking. The main result of this work is a list of GPR indications of cracks, which can be noticed on echograms. It was created through a correlation of the visually-observed cracks with the corresponding echograms, with decimeter accuracy. Several types of GPR responses were classified and linked to possible categories of crack structures, or to processes associated with the presence of cracks (as crumbling, erosion, and lithological alterations). The poor visibility of cracks was also studied, due to small crack size, or to the blurred character of the damaged area, or else to masking effects related to coarse grains in the asphalt mixture. The efficiency of the proposed method for the identification and localization of cracks is higher when a long-term GPR observation is performed.

Krysi?ski, Lech; Sudyka, Jacek

2013-10-01

403

Flexible recognition algorithms and flexible OCR system  

Microsoft Academic Search

An optical handwritten numeral recognition system is presented which uses a G3 facsimile transceiver (fax) as the input device. Flexible recognition algorithms perform raster scanning of the Huffman code produced by the fax only once. The hanger-chain algorithms separate handwritten numerals and obtain the first features at the same time. All the recognition software is coded in Turbo C language.

Du Jiangchuan; Liu Hiengjian

1988-01-01

404

Recycling of plastic and rubber tire waste in asphalt pavements  

SciTech Connect

This paper discusses some important issues related to the use of recycled thermoplastics and rubber tire waste in asphalt binders for hot-mix pavements. Both high temperature rheological and low temperature fracture studies are presented on recycled polyethylene, devulcanized and crumb rubber-modified asphalt binders. The results are compared to unmodified and commercially available modified binders. This research is especially timely in light of the US Intermodal Surface Transportation Efficiency Act of 1991, Section 1038 which, starting in 1995, will force state and local governments to use significant amounts of recycled rubber tire or plastic waste in federally funded highway projects. High temperature rheological measurements of the loss modulus, loss tangent and complex modulus show a significant improvement when only small quantities of crumb rubber, devulcanized crumb rubber or waste polyethylene are added to the asphalt binders. The low temperature fracture performance of the modified asphalts is greatly influenced by the interfacial strength between the dispersed and continuous phase. The fracture toughness increases dramatically, only when low molecular weight polymers are grafted in-situ onto the rubber and polymer dispersed phases in order to strength the interface. This points to a crack-pinning mechanism as being responsible for the dramatic increase in fracture toughness that is observed in this work. Single phase, devulcanized crumb rubber-asphalt systems perform quite poorly at low temperatures.

Morrison, G.R.; Lee, N.K.; Hesp, S.A.M. [Queen`s Univ., Kingston, Ontario (Canada). Dept. of Chemistry

1994-12-31

405

Use of stabilized bottom ash for bound layers of road pavements.  

PubMed

This paper reports about the lab scale results obtained by using stabilized bottom ash (SBA) from an Italian municipal solid waste incinerator as aggregates in cement-bound mixes and asphalt concretes for road pavements. The investigation focused on SBA content. From the road construction point of view, performance related to compaction, volumetric and mechanical properties were assessed. The environmental aspects were investigated performing leaching tests. The results suggested that SBA satisfied the environmental Italian law for reuse of non-hazardous waste but affected significantly the stress-strain behavior of the final products. Therefore a maximum percentage of 10% was suggested. PMID:23535513

Toraldo, Emanuele; Saponaro, Sabrina; Careghini, Alessandro; Mariani, Edoardo

2013-05-30

406

Growth of Hierarchal Mesoporous NiO Nanosheets on Carbon Cloth as Binder-free Anodes for High-performance Flexible Lithium-ion Batteries.  

PubMed

Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6?mAh g(-1) after 120 cycles at a current density of 100?mA g(-1) and 758.1?mAh g(-1) at a high charging rate of 700?mA g(-1) after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices. PMID:25491432

Long, Hu; Shi, Tielin; Hu, Hao; Jiang, Shulan; Xi, Shuang; Tang, Zirong

2014-01-01

407

Growth of Hierarchal Mesoporous NiO Nanosheets on Carbon Cloth as Binder-free Anodes for High-performance Flexible Lithium-ion Batteries  

NASA Astrophysics Data System (ADS)

Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6 mAh g-1 after 120 cycles at a current density of 100 mA g-1 and 758.1 mAh g-1 at a high charging rate of 700 mA g-1 after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices.

Long, Hu; Shi, Tielin; Hu, Hao; Jiang, Shulan; Xi, Shuang; Tang, Zirong

2014-12-01

408

Growth of Hierarchal Mesoporous NiO Nanosheets on Carbon Cloth as Binder-free Anodes for High-performance Flexible Lithium-ion Batteries  

PubMed Central

Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6?mAh g?1 after 120 cycles at a current density of 100?mA g?1 and 758.1?mAh g?1 at a high charging rate of 700?mA g?1 after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices. PMID:25491432

Long, Hu; Shi, Tielin; Hu, Hao; Jiang, Shulan; Xi, Shuang; Tang, Zirong

2014-01-01

409

Flexible Straws.  

ERIC Educational Resources Information Center

Discusses the use of flexible straws for teaching properties of figures and families of shapes. Describes a way to make various two- or three-dimensional geometric shapes. Lists eight advantages of the method. (YP)

Prentice, Gerard

1989-01-01

410

78 FR 26847 - Including Specific Pavement Types in Federal-aid Highway Traffic Noise Analyses  

Federal Register 2010, 2011, 2012, 2013

...three pavement types: dense-graded asphaltic concrete (DGAC), open-graded asphaltic concrete (OGAC), and Portland cement concrete (PCC). Prediction of future noise levels is based on the ``average'' pavement type, calculated as the...

2013-05-08

411

POROUS PAVEMENT PHASE I DESIGN AND OPERATIONAL CRITERIA (EPA/600/2-80/135)  

EPA Science Inventory

Design and operational criteria, utilization concepts, benefits and disadvantages, as well as other characteristics of porous pavements are presented in this report. Particular emphasis is placed on porous asphalt pavements, but the criteria and design approach are applicable to ...

412

Determination of the Presence Conditions of Pavement Markings using Image Processing  

E-print Network

Pavement markings, as a form of traffic control devices, play a crucial role in safely guiding drivers. Restriping pavement markings is an important task in the maintenance of traffic control devices. Every year state agencies spend a lot of money...

Ge, Hancheng

2012-10-19

413

On-site inspections of pavement damages evolution using GPR  

NASA Astrophysics Data System (ADS)

Ground-penetrating radar (GPR) is being increasingly used for pavements maintenance due to the wide range of applications spanning from physical to geometrical inspections, thereby allowing for a reliable diagnosis of the main causes of road structural damages. In this work, an off-ground GPR system was used to investigate a large-scale rural road network. Two sets of surveys were carried out in different time periods, with the main goals to i) localize the most critical sections; ii) monitor the evolution of previous damages and localize newborn deep faults, although not revealed at the pavement surface level; iii) analyze the causes of both evolution and emergence of faults by considering environmental and human factors. A 1-GHz GPR air-launched antenna was linked to an instrumented van for collecting data at traffic speed. Other support techniques (e.g. GPS data logger, odometer, HD video camera) were used for cross-checking,. Such centre frequency of investigation along with a 25-ns time window allow for a signal penetration of 900 mm, consistent with the deepest layer interfaces. The bottom of the array was 400 mm over the surface, with a minimum distance of 1200 mm from the van body. Scan length of maximum 10 km were provided for avoiding heavy computational loads. The rural road network was located in the District of Rieti, 100 km north from Rome, Italy, and mostly develops in a hilly and mountainous landscape. In most of the investigated roads, the carriageway consists in two lanes of 3.75 meters wide and two shoulders of 0.50 meters wide. A typical road section includes a HMA layer (65 mm average thickness), a base layer (100 mm average thickness), and a subbase layer (300 mm average thickness), as described by pavement design charts. The first set of surveys was carried out in two days at the beginning of spring in moderately dry conditions. Overall, 320-km-long inspections were performed in both travel directions, thereby showing a productivity of approximately 160 km/day at 40 km/h speed, on the average. After processing and first-checking, GPR profiles were divided into homogeneous sections according to the combination of different parameters (e.g. route analyzed, long distance conditions of regularity/irregularity in layers arrangement). In such context, a high consistency between surface damages, mismatches from the GPR scans, and boundary environmental conditions was demonstrated. In addition, deep mismatches were detected even for early-stage or unrevealed faults. The second set of surveys was carried out in autumn in high humidity conditions, due to recent rainfalls. 160 km of relevant routes from the same road network were investigated. Results showed a high consistency with those collected during the first-stage of surveys. Minor changes were found in those sections with low traffic loads (e.g. farther away from the biggest town of Rieti), whereas major mismatches were detected in wetlands (e.g. close to rivers), work zones, and nearby those sections already deeply damaged in the past. This work benefited from networking activities carried out within the EU funded COST Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar'.

Tosti, Fabio; D'Amico, Fabrizio; Calvi, Alessandro; Benedetto, Andrea

2014-05-01

414

High performance flexible top-emitting warm-white organic light-emitting devices and chromaticity shift mechanism  

SciTech Connect

Flexible warm-white top-emitting organic light-emitting devices (TEOLEDs) are fabricated onto PET substrates with a simple semi-transparent cathode Sm/Ag and two-color phosphors respectively doped into a single host material TCTA. By adjusting the relative position of the orange-red EML sandwiched between the blue emitting layers, the optimized device exhibits the highest power/current efficiency of 8.07 lm/W and near 13 cd/A, with a correlated color temperature (CCT) of 4105 K and a color rendering index (CRI) of 70. In addition, a moderate chromaticity variation of (-0.025, +0.008) around warm white illumination coordinates (0.45, 0.44) is obtained over a large luminance range of 1000 to 10000 cd/m{sup 2}. The emission mechanism is discussed via delta-doping method and single-carrier device, which is summarized that the carrier trapping, the exciton quenching, the mobility change and the recombination zone alteration are negative to color stability while the energy transfer process and the blue/red/blue sandwiched structure are contributed to the color stability in our flexible white TEOLEDs.

Shi, Hongying; Deng, Lingling; Chen, Shufen, E-mail: iamsfchen@njupt.edu.cn, E-mail: wei-huang@njupt.edu.cn; Xu, Ying; Zhao, Xiaofei; Cheng, Fan [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China)] [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China); Huang, Wei, E-mail: iamsfchen@njupt.edu.cn, E-mail: wei-huang@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China) [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China); Jiangsu-Singapore Joint Research Center for Organic/Bio- Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Technology, Nanjing 211816 (China)

2014-04-15

415

Deconstructing a Plant Macromolecular Assembly: Chemical Architecture, Molecular Flexibility, And Mechanical Performance of Natural and Engineered Potato Suberins  

PubMed Central

Periderms present in plant barks are essential protective barriers to water diffusion, mechanical breakdown, and pathogenic invasion. They consist of densely packed layers of dead cells with cell walls that are embedded with suberin. Understanding the interplay of molecular structure, dynamics, and biomechanics in these cell wall-associated insoluble amorphous polymeric assemblies presents substantial investigative challenges. We report solid-state NMR coordinated with FT-IR and tensile strength measurements for periderms from native and wound-healing potatoes and from potatoes with genetically modified suberins. The analyses include the intact suberin aromatic–aliphatic polymer and cell-wall polysaccharides, previously reported soluble depolymerized transmethylation products, and undegraded residues including suberan. Wound-healing suberized potato cell walls, which are 2 orders of magnitude more permeable to water than native periderms, display a strikingly enhanced hydrophilic–hydrophobic balance, a degradation-resistant aromatic domain, and flexibility suggestive of an altered supramolecular organization in the periderm. Suppression of ferulate ester formation in suberin and associated wax remodels the periderm with more flexible aliphatic chains and abundant aromatic constituents that can resist transesterification, attenuates cooperative hydroxyfatty acid motions, and produces a mechanically compromised and highly water-permeable periderm. PMID:24502663

2015-01-01

416

Analysis of aggregate imaging system (AIMS) measurements and their relationship to asphalt pavement skid resistance  

E-print Network

) ........................................................9 2.3 Schematic of Hysteresis and Adhesive Forces Acting on Tire-Pavement Interface (Bazlamit and Reza 2005)..............................................................10 2.4 Aggregate Methods for Providing Pavement Texture (Dahir 1979... forces combine to give a pavement its skid resistance, hysteresis and adhesion. These forces are the result of interaction between the different texture scales on the pavement surface and the tire. Figure 2.3, from Bazlamit and Reza (2005), shows...

Luce, Anthony David

2009-05-15

417

Characterization of cementitiously stabilized subgrades for mechanistic-empirical pavement design  

NASA Astrophysics Data System (ADS)

Pavements are vulnerable to subgrade layer performance because it acts as a foundation. Due to increase in the truck traffic, pavement engineers are challenged to build more strong and long-lasting pavements. To increase the load-bearing capacity of pavements, subgrade layer is often stabilized with cementitious additives. Thus, an overall characterization of stabilized subgrade layer is important for enhanced short- and long-term pavement performance. In this study, the effect of type and amount of additive on the short-term performance in terms of material properties recommended by the new Mechanistic-Empirical Pavement Design Guide (MEPDG) is examined. A total of four soils commonly encountered as subgrades in Oklahoma are utilized. Results show that the changes in the Mr, ME and UCS values stabilized specimens depend on the soil type and properties of additives. The long-term performance (or durability) of stabilized soil specimens is investigated by conducting freeze-thaw (F-T) cycling, vacuum saturation and tube suction tests on 7-day cured P-, K- and C-soil specimens stabilized with 6% lime, 10% CFA and 10% CKD. This study is motivated by the fact that during the service life of pavement stabilized layers are subjected to F-T cycles and moisture variations. It is found that that UCS value of all the stabilized specimens decreased with increase in the number of F-T cycles. A strong correlation was observed between UCS values retained after vacuum saturation and F-T cycles indicating that vacuum saturation could be used as a time-efficient and inexpensive method for evaluating durability of stabilized soils. In this study, short- and long-term observations from stabilization of sulfate bearing soil with locally available low (CFA), moderate (CKD) and high (lime) calcium-based stabilizers are determined to evaluate and compare the effect of additive type on the phenomenon of sulfate-induced heave. The impact of different factors on the development of the ettringite, responsible for sulfate-induced heaving, is also discussed. For Level 2 design of pavements, a total of four stress-based statistical models and two feed-forward-type artificial neural network (ANN) models, are evaluated for predicting resilient modulus of 28-day cured stabilized specimens. Specifically, one semi-log stress-based, three log-log stress-based, one Multi-Layer Perceptrons Network (MLPN), and one Radial Basis Function Network (RBFN) are developed. Overall, semi-log stress-based and MLPN neural network are found to show best acceptable performance for the present evaluation and validation datasets. Further, correlations are presented for stress-based models to correlate Mr with compacted specimen characteristics and soil/additive properties. Additionally, the effect of type of additive on indirect tensile and fatigue characteristics of selected stabilized P- and V-soil is evaluated. This study is based on the fact that stabilized layer is subjected to tensile stresses under wheel loading. Thus, the resilient modulus in tension (M rt), fatigue life and strength in tension (sigmat) or flexure (represented by modulus of rupture, MOR) becomes another important design parameter within the mechanistic framework. Cylindrical specimens are prepared, cured for 28 days and subjected to different stress sequences in indirect tension to study the Mrt. On the other hand, stabilized beam specimens are compacted using a Linear Kneading Compactor and subjected to repeated cycles of reloading-unloading after 28 days of curing in a four-point beam fatigue apparatus for evaluating fatigue life and flexural stiffness. It is found that all three additives improved the Mrt, sigmat and MOR values; however, degree of improvement varied with the type of additive and soil. This study encompasses the differences in the design of semi-rigid pavements developed using AASHTO 1993 and AASHTO 2002 MEPDG methodologies. Further, the design curves for fatigue performance prediction of stabilized layers are developed for different stabilized pavement sections. Knowledge gained f

Solanki, Pranshoo

418

Acute Effects of Two Different Warm-Up Protocols on Flexibility and Lower Limb Explosive Performance in Male and Female High Level Athletes  

PubMed Central

This study examined the effects of two different warm-up protocols on lower limb power and flexibility in high level athletes. Twenty international level fencers (10 males and 10 females) performed two warm-up protocols that included 5-min light jogging and either short (15s) or long (45s) static stretching exercises for each of the main leg muscle groups (quadriceps, hamstrings and triceps surae), followed by either 3 sets of 3 (short stretching treatment), or 3 sets of 5 tuck jumps (long stretching treatment), in a randomized crossover design with one week between treatments. Hip joint flexion was measured with a Lafayette goniometer before and after the 5-min warm-up, after stretching and 8 min after the tuck jumps, while counter movement jump (CMJ) performance was evaluated by an Ergojump contact platform, before and after the stretching treatment, as well as immediately after and 8 minutes after the tuck jumps. Three way ANOVA (condition, time, gender) revealed significant time (p < 0.001) and gender (p < 0.001) main effects for hip joint flexion, with no interaction between factors. Flexibility increased by 6. 8 ± 1.1% (p < 0.01) after warm-up and by another 5.8 ± 1.6% (p < 0.01) after stretching, while it remained increased 8 min after the tuck jumps. Women had greater ROM compared with men at all time points (125 ± 8° vs. 94 ± 4° p<0.01 at baseline), but the pattern of change in hip flexibility was not different between genders. CMJ performance was greater in men compared with women at all time points (38.2 ± 1.9 cm vs. 29.8 ± 1.2 cm p < 0.01 at baseline), but the percentage of change CMJ performance was not different between genders. CMJ performance remained unchanged throughout the short stretching protocol, while it decreased by 5.5 ± 0.9% (p < 0.01) after stretching in the long stretching protocol However, 8 min after the tuck jumps, CMJ performance was not different from the baseline value (p = 0.075). In conclusion, lower limb power may be decreased after long periods of stretching, but performance of explosive exercises may reverse this phenomenon. Key points Stretching of the main leg muscle groups for 45 s results in a relatively large decrease (by 5.5%) in subsequent jumping performance Stretching of the main leg muscle groups for only 15 s results in an increase in flexibility similar to that of the longer duration stretching (by 12.6%), with no change in subsequent jumping performance Performance of a PAP exercise such as tuck jumps may reverse the negative effects of long duration stretching on leg muscle power. However, jumping performance is not increased above baseline Speed/power athletes should be advised against using long duration stretching. The number of repetitions of a PAP exercise such as the tuck jumps, should be further examined in order to induce an increase in explosive performance during competition PMID:24150077

Tsolakis, Charilaos; Bogdanis, Gregory C.

2012-01-01

419

FIELD AND COMPUTER SIMULATION EXPERIMENTS ON THE FORMATION OF DESERT PAVEMENT  

E-print Network

FIELD AND COMPUTER SIMULATION EXPERIMENTS ON THE FORMATION OF DESERT PAVEMENT JOHN WAINWRIGHT1), to observe the speed at which desert pavement surfaces could be re-established following disturbance erosion processes. Copyright # 1999 John Wiley & Sons, Ltd. KEY WORDS: raindrop erosion; desert pavement

Ahmad, Sajjad

420

Evaluation of infiltration in layered pavements using surface GPR reflection techniques  

E-print Network

Evaluation of infiltration in layered pavements using surface GPR reflection techniques K. Grotea The bearing capacity of sub-asphalt soils, which is a critical parameter for assessing pavement conditions and guiding pavement maintenance, is greatly influenced by soil water content. In this study, ground

Hubbard, Susan

421

ROUGH THIN PAVEMENT THICKNESS ESTIMATION BY GPR N. Pinel, L. Liu, C. Bourlier, Y. Wang  

E-print Network

ROUGH THIN PAVEMENT THICKNESS ESTIMATION BY GPR N. Pinel, L. Liu, C. Bourlier, Y. Wang IREENA pavements consider flat interfaces for simpli- fication. In this paper, the roughness of the surfaces is taken into account. First, the amplitudes of the first two echoes from the rough thin pavement

Paris-Sud XI, Université de

422

EVALUATION OF THE PAVEMENT STRUCTURAL CONDITION AT NETWORK LEVEL USING FALLING WEIGHT  

E-print Network

EVALUATION OF THE PAVEMENT STRUCTURAL CONDITION AT NETWORK LEVEL USING FALLING WEIGHT DEFLECTOMETER agencies to improve the surface condition of pavements, but these measures have not successfully prevented the problem from reoccurring. As a result, the overall pavement condition keeps deteriorating because

Manuel, Lance

423

FRP Dowels for Concrete Pavements Darren Eddie, Junior Structural Engineer, Reid Crowther & Partners;  

E-print Network

= L FRP Dowels for Concrete Pavements By Darren Eddie, Junior Structural Engineer, Reid Crowther - Introduction Joints are used in concrete pavements in order to control cracking due to thermal pavements due to the expansion of steel during the corrosion process. This expansion can create large

424

of Transportation Rigid Pavement Design and Analysis Web-Based Training Site  

E-print Network

Texas Department of Transportation Rigid Pavement Design and Analysis Web-Based Training Site Highway Administration Texas Department of Transportation, 2004 Rigid Pavement Design and Analysis Web for six computer programs pertaining mainly to the design and analysis of rigid pavements. The programs

Texas at Austin, University of

425

A four-point bending test for the bonding evaluation of composite pavement  

E-print Network

A four-point bending test for the bonding evaluation of composite pavement M. Hun1 , A. Chabot1 , F investigate the crack initiation and propagation at the interface between layers of composite pavements affects the durability of composite pavements made with asphalt and cement materials. Two main problems

Paris-Sud XI, Université de

426

FREE-FORM ANISOTROPY: A NEW METHOD FOR CRACK DETECTION ON PAVEMENT SURFACE IMAGES  

E-print Network

FREE-FORM ANISOTROPY: A NEW METHOD FOR CRACK DETECTION ON PAVEMENT SURFACE IMAGES Tien Sy NGUYEN(1, in the segmentation step, for crack detection on road pavement images. Features which are calculated along every free on some samples of different kinds of pavements. Results of the method are also given on other kinds

Paris-Sud XI, Université de

427

Concrete Pavement I-285 under 5th runway at Hartsfield Jackson  

E-print Network

Concrete Pavement Sweet as a James Page I-285 under 5th runway at Hartsfield Jackson International Concrete Paving project I-285 East Perimeter Fiscal 2012 GDOT placed 205,704 square yards of RCC Pavement Portland Cement Concrete Pavement State Route 96 Crawford / Peach Counties I-75 Tift County CRC Lane

428

Influences of eolian and pedogenic processes on the origin and evolution of desert pavements  

E-print Network

Influences of eolian and pedogenic processes on the origin and evolution of desert pavements Leslie in the evolution of these pavements. Eolian dust (I) I=leroles mechanical mogmentatloa oIliow rock, providing the source materiaJ for pavements., and (2) accumulates slowly below basaIdc colluvium in Row depressions

Ahmad, Sajjad

429

Evolution of desert pavements and the vesicular layer in soils of the Transantarctic Mountains  

E-print Network

Evolution of desert pavements and the vesicular layer in soils of the Transantarctic Mountains: Desert soils Soil chronosequences Pavement development index Ventifaction Desert varnish Compared to mid-latitude deserts, the properties, formation and evolution of desert pavements and the underlying vesicular layer

Ahmad, Sajjad

430

Advanced Characterisation of Pavement and Soil Engineering Materials Loizos, Scarpas & Al-Qadi (eds)  

E-print Network

1241 Advanced Characterisation of Pavement and Soil Engineering Materials ­ Loizos, Scarpas & Al and economical alternative for the repair of deteriorated pavements, reflective cracking continues to be major approaches have not provided a direct means for the study of crack initiation and propagation in pavements

Paulino, Glaucio H.

431

DETERMINATION OF ENERGY RELEASE RATE FOR A MIXED-MODE DEBONDING TEST FOR "COMPOSITE" PAVEMENTS  

E-print Network

DETERMINATION OF ENERGY RELEASE RATE FOR A MIXED-MODE DEBONDING TEST FOR "COMPOSITE" PAVEMENTS in "composite" pavement consisting of superimposed layers of processed materials (cement concrete and bituminous, mixed-mode test, multiparticle modelling, Dunder, pavement Due to the structural heterogeneity

Boyer, Edmond

432

FILTERING OF ARTIFACTS AND PAVEMENT SEGMENTATION FROM MOBILE Jorge Hernandez and Beatriz Marcotegui  

E-print Network

FILTERING OF ARTIFACTS AND PAVEMENT SEGMENTATION FROM MOBILE LIDAR DATA Jorge Hern the contour between pavements and roads. The method uses a quasi-flat zone algorithm and a region adjacency boundary. Finally, edges with a value compatible with the pavement/road difference (about 14[cm

Cord, Aurélien

433

Pavement Boundary Detection Via Circular Shape Models Bing Ma \\Lambda Sridhar Lakshmanan Alfred O. Hero  

E-print Network

Pavement Boundary Detection Via Circular Shape Models Bing Ma \\Lambda Sridhar Lakshmanan Alfred O bingm@umich.edu lakshman@umich.edu hero@eecs.umich.edu Abstract Automated detection of pavement of art systems for detecting and tracking pavement boundaries use a priori shape models to describe

Hero, Alfred O.

434

EVALUATION OF THE INFLUENCE OF TACK COAT CONSTRUCTION FACTORS ON THE BOND STRENGTH BETWEEN PAVEMENT LAYERS  

E-print Network

EVALUATION OF THE INFLUENCE OF TACK COAT CONSTRUCTION FACTORS ON THE BOND STRENGTH BETWEEN PAVEMENT Evaluation of the Influence of Tack Coat Construction Factors on the Bond Strength between Pavement Layers 7 provided by the tack coat at the interface between pavement layers. These factors included the surface

435

Dynamical Processes on Desert Pavements and the Healing of Surficial Disturbances  

E-print Network

Dynamical Processes on Desert Pavements and the Healing of Surficial Disturbances PETER K. HAFF, California, 92093-0225 Received June 16, 1994 Mature desert pavements are traditionally regarded as hall period on small cleared patches, or plats, on pavement sur- faces in Panamint Valley, California

Ahmad, Sajjad

436

Evaluation of the Structure-induced Rolling Resistance (SRR) for pavements including  

E-print Network

Evaluation of the Structure-induced Rolling Resistance (SRR) for pavements including viscoelastic.chupin@ifsttar.fr Abstract: This article addresses the question of whether the viscoelastic behavior of asphalt pavements consumption of road traffic, as compared to non-dissipative pavements. In the context of sustainable

Paris-Sud XI, Université de

437

5-9035-01-P4 4-YEAR PAVEMENT MANAGEMENT PLAN (WITH  

E-print Network

5-9035-01-P4 4-YEAR PAVEMENT MANAGEMENT PLAN (WITH PROPOSITION 12 PROJECTS): ANALYSIS REPORT Implementation of a Web-based GIS System to Provide Information for Pavement Maintenance Decision-Making DECEMBER Table of Contents Section 1. Pavement Management Plan Executive Summary

Texas at Austin, University of

438

Although most Minnesota airports do not have much concrete pavement, the con-  

E-print Network

Although most Minnesota airports do not have much concrete pavement, the con- crete they do have are generally constructed out of concrete that is much thicker. Maintaining any section of pavement, regardless of its size, is important for pre- serving its condition and optimizing pave- ment life. Pavement

Minnesota, University of

439

Do et al. 1 Full Scale Tests for the Assessment of Wear of Pavement Surfaces  

E-print Network

Do et al. 1 Full Scale Tests for the Assessment of Wear of Pavement Surfaces Minh-Tan Do subjected to heavy traffic. Reports can be found in (1)(2). Evolution of pavements during its whole service shown in the figure 2. By this way, during tests on one track, pavement construction can be carried out

Boyer, Edmond

440

Response of desert pavement to seismic shaking, Hector Mine earthquake, California, 1999  

E-print Network

Response of desert pavement to seismic shaking, Hector Mine earthquake, California, 1999 P. K. Haff characteristic surface disturbances on nearby desert pavements. These disturbances included (1) zones of wholesale gravel displacement interspersed with zones of intact pavement, (2) displaced and rotated cobbles

Ahmad, Sajjad

441

Nondestructive pavement evaluation technique using falling weight deflectometer  

SciTech Connect

An analytical method to predict the mechanical properties of a multi-layer pavement structure is presented. The development of the model is based on a modified back calculation model, using a finite circular plate resting on an elastic layered system. The deflection of the pavement under the dynamic action of the falling weight deflectometer (FWD) is taken as a function of the load action and the characteristic strength of the layers comprising the system including the friction between the individual layers. The responses of the pavement during the impact loading of the falling weight are measured and analyzed to predict the stress, strain and coefficient of friction between the layers making the system. The results revealed that the model which incorporates the interface of friction coefficient in the back-analysis technique allows for a more accurate calculation of the mechanical properties of the pavements and thus can be used as a quality control to assess the state of adhesion between the pavement layer system.

Al-Nageim, H.; Al-Hakim, B.; Lesley, L. [John Moores Univ., Liverpool (United Kingdom). School of the Built Environment

1996-11-01

442

Urban evaporation rates for water-permeable pavements.  

PubMed

In urban areas the natural water balance is disturbed. Infiltration and evaporation are reduced, resulting in a high surface runoff and a typical city climate, which can lead to floods and damages. Water-permeable pavements have a high infiltration rate that reduces surface runoff by increasing the groundwater recharge. The high water retention capacity of the street body of up to 51 l/m(2) and its connection via pores to the surface lead to higher evaporation rates than impermeable surfaces. A comparison of these two kinds of pavements shows a 16% increase in evaporation levels of water-permeable pavements. Furthermore, the evaporation from impermeable pavements is linked directly to rain events due to fast-drying surfaces. Water-permeable pavements show a more evenly distributed evaporation after a rain event. Cooling effects by evaporative heat loss can improve the city climate even several days after rain events. On a large scale use, uncomfortable weather like sultriness or dry heat can be prevented and the urban water balance can be attenuated towards the natural. PMID:20818060

Starke, P; Göbel, P; Coldewey, W G

2010-01-01

443

Thermal conductance of and heat generation in tire-pavement interface and effect on aircraft braking  

NASA Technical Reports Server (NTRS)

A finite-difference analysis was performed on temperature records obtained from a free rolling automotive tire and from pavement surface. A high thermal contact conductance between tire and asphalt was found on a statistical basis. Average slip due to squirming between tire and asphalt was about 1.5 mm. Consequent friction heat was estimated as 64 percent of total power absorbed by bias-ply, belted tire. Extrapolation of results to aircraft tire indicates potential braking improvement by even moderate increase of heat absorbing capacity of runway surface.

Miller, C. D.

1976-01-01

444

A comparative reliability and performance study of different stent designs in terms of mechanical properties: foreshortening, recoil, radial force, and flexibility.  

PubMed

This study seeks to improve the mechanical performance of stents by conducting reliability performance testing and finite element method (FEM)-based simulations for coronary stents. Three commercially available stent designs and our own new design were tested to measure the factors affecting performance, specifically foreshortening, recoil, radial force, and flexibility. The stents used in the present experiments were 3?mm in working diameter and 18?mm of working length. The results of the experiments indicate that the foreshortening of stents A, B, C, and our new design, D, was equivalent to 2.25, 0.67, 0.46, and 0.41%, respectively. The recoil of stents A, B, C, and D was 6.00, 4.35, 3.50, and 4.36%, respectively. Parallel plate radial force measurements were A, 3.72?±?0.28?N; B, 3.81?±?0.32?N; C, 4.35?±?0.18?N; and D, 4.02?±?0.24?N. Radial forces determined by applying uniform pressure in the circumferential direction were A, 28.749?±?0.81?N; B, 32.231?±?1.80?N; C, 34.522?±?3.06?N; and D, 42.183?±?2.84?N. The maximum force of crimped stent at 2.2-mm deflection was 1.01?±?0.08?N, 0.82?±?0.08?N, 0.92?±?0.12?N, and 0.68?±?0.07?N for each of stents A, B, C and D. The results of this study enabled us to identify several factors to enhance the performance of stents. In comparing these stents, we found that our design, stent D, which was designed by a collaborative team from seven universities, performed better than the commercial stents across all parameter of foreshortening, recoil, radial force, and flexibility. PMID:23461583

Kim, Dong Bin; Choi, Hyuk; Joo, Sang Min; Kim, Han Ki; Shin, Jae Hee; Hwang, Min Ho; Choi, Jaesoon; Kim, Dong-Gon; Lee, Kwang Ho; Lim, Chun Hak; Yoo, Sun Kook; Lee, Heung-Man; Sun, Kyung

2013-04-01

445

Hot in-place recycling of asphalt pavements. Master's thesis  

SciTech Connect

The purpose of this report is to identify factors to consider in selecting a hot in-place recycling project for asphalt pavements. This report discusses the different types of recycling processes and several selected hot in-place recycling processes that are becoming so popular today. The types of asphalt pavement distress and their causes are discussed to provide a working knowledge of possible applications for this process. Discussions on project selection, design, and construction considerations will also provide an awareness of considerations relative to this type of asphalt-pavement rehabilitation. An understanding of these topics will be helpful when selecting hot in-place recycling. The information that this report is based upon was obtained from various sources. A literature search included technical reports, periodicals, and advertisements. Personal contact was made in the form of interviews with a number of representatives in the industry and on site inspection of Cutler Repaving, Inc. and Remixer Contracting Co., Inc. operations.

Dowdy, M.L.

1987-08-04

446

The effects of buffer layers on the performance and stability of flexible InGaZnO thin film transistors on polyimide substrates  

SciTech Connect

We demonstrated the fabrication of flexible amorphous indium gallium zinc oxide thin-film transistors (TFTs) on high-temperature polyimide (PI) substrates, which were debonded from the carrier glass after TFT fabrication. The application of appropriate buffer layers on the PI substrates affected the TFT performance and stability. The adoption of the SiN{sub x}/AlO{sub x} buffer layers as water and hydrogen diffusion barriers significantly improved the device performance and stability against the thermal annealing and negative bias stress, compared to single SiN{sub x} or SiO{sub x} buffer layers. The substrates could be bent down to a radius of curvature of 15?mm and the devices remained normally functional.

Ok, Kyung-Chul; Park, Jin-Seong, E-mail: hkim-2@naver.com, E-mail: jsparklime@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Ko Park, Sang-Hee; Kim, H., E-mail: hkim-2@naver.com, E-mail: jsparklime@hanyang.ac.kr [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Hwang, Chi-Sun [Transparent Electronics Team, ETRI, Daejeon 305-350 (Korea, Republic of); Soo Shin, Hyun; Bae, Jonguk [LG Display R and D Center, LG Display Co., Ltd., Paju 413-811 (Korea, Republic of)

2014-02-10

447

Comparative Occupational Survey of Civilian and Military Members in the Pavements Maintenance and Construction Equipment Operator Specialties. Final Report for Period 1 October 1975-30 October 1977.  

ERIC Educational Resources Information Center

A study was conducted to analyze and compare the job performance of civil service and military pavements maintenance workers and construction equipment operators. A military sample of 2,675 and a civilian sample of 1,974 were surveyed by means of a job inventory checklist and relative time spent rating method. Of the three job types that were…

Cowan, Douglas K.

448

An algorithm for pavement crack detection based on multiscale space  

NASA Astrophysics Data System (ADS)

Conventional human-visual and manual field pavement crack detection method and approaches are very costly, time-consuming, dangerous, labor-intensive and subjective. They possess various drawbacks such as having a high degree of variability of the measure results, being unable to provide meaningful quantitative information and almost always leading to inconsistencies in crack details over space and across evaluation, and with long-periodic measurement. With the development of the public transportation and the growth of the Material Flow System, the conventional method can far from meet the demands of it, thereby, the automatic pavement state data gathering and data analyzing system come to the focus of the vocation's attention, and developments in computer technology, digital image acquisition, image processing and multi-sensors technology made the system possible, but the complexity of the image processing always made the data processing and data analyzing come to the bottle-neck of the whole system. According to the above description, a robust and high-efficient parallel pavement crack detection algorithm based on Multi-Scale Space is proposed in this paper. The proposed method is based on the facts that: (1) the crack pixels in pavement images are darker than their surroundings and continuous; (2) the threshold values of gray-level pavement images are strongly related with the mean value and standard deviation of the pixel-grey intensities. The Multi-Scale Space method is used to improve the data processing speed and minimize the effectiveness caused by image noise. Experiment results demonstrate that the advantages are remarkable: (1) it can correctly discover tiny cracks, even from very noise pavement image; (2) the efficiency and accuracy of the proposed algorithm are superior; (3) its application-dependent nature can simplify the design of the entire system.

Liu, Xiang-long; Li, Qing-quan

2006-10-01

449

Evaluation of multilayered pavement structures from measurements of surface waves  

USGS Publications Warehouse

A method is presented for evaluating the thickness and stiffness of multilayered pavement structures from guided waves measured at the surface. Data is collected with a light hammer as the source and an accelerometer as receiver, generating a synthetic receiver array. The top layer properties are evaluated with a Lamb wave analysis. Multiple layers are evaluated by matching a theoretical phase velocity spectrum to the measured spectrum. So far the method has been applied to the testing of pavements, but it may also be applicable in other fields such as ultrasonic testing of coated materials. ?? 2006 American Institute of Physics.

Ryden, N.; Lowe, M.J.S.; Cawley, P.; Park, C.B.

2006-01-01

450

Impact of compressed natural gas fueled buses on street pavements  

SciTech Connect

Capital Metro, the Ausin, Texas transit authority, is currently evaluating a number of CNG fueled buses. As part of the U.S. DOT Region Six University Transportation Centers Program (UTCP), a study was instigated into the scale of incremental pavement consumption associated with the operation of these buses. The study suggests that replacing current vehicles with CNG powered models utilizing aluminum storage tanks would raise average network equivalent single rehabilitation costs across the network of over four percent. Finally, it recommends that full cost study be undertaken with evaluation of the adoption of alternative bus fuels - which includes pavement and environmental impacts.

Yang, D.; Harrison, R.

1995-07-01

451

Thin, applied surfacing for improving skid resistance of concrete pavements  

NASA Astrophysics Data System (ADS)

The use of select aggregate in a thin wearing surface of portland cement mortar to prolone or restore a concrete pavement's ability to develop high friction was accomplished. Two fine aggregates, blast furnace slag and lightweight expanded shale were found to exhibit skid resistance greater than the other aggregates evaluated. The British polishing wheel was used in the laboratory evaluation of aggregate to simulate wear. The need for a method of restoring friction to a worn, but otherwise sound concrete pavement led to a field evaluation of several different techniques for placing a very thin overlay. The successful method was a broomed, very thin layer of mortar, 3 mm thick.

Scholer, C. F.

1980-12-01

452

Desert pavements and associated rock varnish in the Mojave Desert: How old can they be?  

NASA Astrophysics Data System (ADS)

Desert pavements are common features of arid landscapes and have been widely used as a relative age indicator of the geomorphic surfaces upon which they are developed. In this study I examined the patterns of pavement development as a function of elevation in the Mojave Desert as well as the causes for the gradual disappearance of pavement at high elevations. Pavement density, as measured by percentage of pebble coverage, decreases systematically with elevation gain by ˜3% per 100 m, from 95% coverage below 500 m to less than 60% at 1700 m. Plants appear to be the main agent of pavement disruption; plant density decreases as pavement density increases. Burrowing by rodents and crusting by cryptobiota also disrupt pavement development at higher elevation. During the last glacial maximum, plant communities were displaced 1000 1400 m downward in the Mojave Desert. Pavements today generally do not survive above the blackbush (Coleogyne ramossisma)-sagebrush (Artemisia tridentata) zone. Evidence from packrat middens shows that these and other plants typical of high elevations today grew as low as 300 400 m during the last glacial maximum. I suggest that during the last glacial maximum, desert pavements were confined to the lowest alluvial fans of Death Valley and adjoining low valleys. No alluvial desert pavements above ˜400 m in the region are older than the latest Pleistocene. By the same reasoning, desert varnish on desert pavements above 400 m may all be Holocene in age, except where developed on stable boulders.

Quade, Jay

2001-09-01

453

Asphalt additives in thick hot mixed asphalt-concrete pavements. Research report (Interim), Sep 86-Oct 90  

SciTech Connect

Asphalt concrete field test pavements were placed in District 19 north of Texarkana on US-59/71 in 1987 and 1988 to evaluate the ability of certain asphalt additives to enhance resistance to cracking and rutting. Two 10-inch thick and 0.9 mile (approx.) long test pavements and a similar untreated control section were constructed in the northbound and southbound lanes for a total of 6 field trials. Asphalt additives were incorporated in both the 8-inch base and the overlying 2-inch surface layers. The additives evaluated included Goodyear LPF 5812, Chemkrete-CTI 102, Exxon Polybilt 102, and Styrelf 13. Samples of paving materials including aggregates, asphalts, compacted mixes, and pavement cores were collected, conveyed to the laboratory, and tested to provide detailed documentation of their properties. Tests included rheological properties of the binders before and after artificial aging, characterization of aggregate, Hveem and Marshall stability, stiffness as a function of temperature, tensile properties before and after moisture conditioning and artificial aging, air void content, creep, and permanent deformation. Field tests and visual evaluations have been conducted to objectively evaluate field performance. Results of these tests are reported herein. Within 6 months after construction of the base layers and prior to placement of the surface course, the Chemkrete modified base became severely cracked. As a result, the surface mix placed on this base section was treated with Goodyear latex rather than Chemkrete. All other modified pavements and the control section have performed well and exhibited essentially equivalent performance after 2 1/2 years in service.

Button, J.W.; Prapnnachari, S.

1991-01-01

454

Lightweight and flexible reduced graphene oxide/water-borne polyurethane composites with high electrical conductivity and excellent electromagnetic interference shielding performance.  

PubMed

In this study, we developed a simple and powerful method to fabricate flexible and lightweight graphene-based composites that provide high electromagnetic interference (EMI) shielding performance. Electrospun waterborne polyurethane (WPU) that featured sulfonate functional groups was used as the polymer matrix, which was light and flexible. First, graphene oxide (GO)/WPU composites were prepared through layer-by-layer (L-b-L) assembly of two oppositely charged suspensions of GO, the cationic surfactant (didodecyldimethylammonium bromide, DDAB)-adsorbed GO and intrinsic negatively charged GO, depositing on the negatively charged WPU fibers. After the L-b-L assembly cycles, the GO bilayers wrapped the WPU fiber matrix completely and revealed fine connections guided by the electrospun WPU fibers. Then, we used hydroiodic acid (HI) to obtain highly reduced GO (r-GO)/WPU composites, which exhibited substantially enhanced electrical conductivity (approximately 16.8 S/m) and, moreover, showed a high EMI-shielding effectiveness (approximately 34 dB) over the frequency range from 8.2 to 12.4 GHz. PMID:24921939

Hsiao, Sheng-Tsung; Ma, Chen-Chi M; Liao, Wei-Hao; Wang, Yu-Sheng; Li, Shin-Ming; Huang, Yu-Chin; Yang, Ruey-Bin; Liang, Wen-Fan

2014-07-01

455

The use of fluvial and marine sediments in the formulation of roller compacted concrete for use in pavements.  

PubMed

In the manufacture of Roller Compacted Concrete (RCC) used for pavement materials, various types of aggregates are used, such as crushed and rolled limestone or siliceous aggregates. The main objective is always to reach the maximum compactness to achieve higher mechanical performances. In the present work, fluvial and marine sediments, resulting from the dredging of harbours and rivers, were introduced as aggregates in the preparation of RCC for pavement construction, with a view to improving the mechanical strength of the RCC. This study included a granulometric, mineralogical and chemical characterization of the aggregates. The work also contains a mechanical characterization of the resulting material. The objective of the study was to find a resistant RCC, by developing materials such as sediments that are often classified as a waste and where their storage is harmful to the environment. The mechanical strengths obtained showed the profitability of using a Roller Compacted Concrete containing sediments. PMID:19705664

Zdiri, M; Abriakb, N E; Ben Ouezdoua, M; Neji, J

2009-07-01

456

Desert pavement morphology and dynamics, Big Bend National Park, Texas  

E-print Network

Desert pavements consist of a one- to two-layer thick surface armory of stones overlying finer, virtually stone-free material which often adopts the appearance of a meticulously tiled mosaic. They cover half of the arid land surface in North America...

Harmon, Courtney Michelle

2009-05-15

457

Alternative aircraft loading index for pavement structural analysis  

SciTech Connect

The most common practical way to simplify the structural analysis of airfield pavements is the use of equivalent single wheel load models instead of the actual gear of the aircrafts. As the accuracy and reliability of these models strongly affects the design and evaluation of airfield pavements, there is considerable need to investigate both system approaches. The first one, which uses a constant value for the pressure while the radius is variable, is currently under use by the aircraft classification number-pavement classification number method of the International Civil Aviation Organization, but despite this fact it proved to be inadequate to express the aircraft loading in many situations. On the contrary, according to this study, the second model, which has a constant value for the radius while the pressure varies, is more reliable, and it can be an interesting alternative. Thus, based on this model, an aircraft loading index is introduced, which aims to be a simple and reliable factor for expressing the severity of the loading of the aircrafts and a utility for several matters related to the airfield pavement applications.

Loizos, A.; Charonitis, G. [National Technical Univ. of Athens (Greece)] [National Technical Univ. of Athens (Greece)

1999-05-01

458

AREA UNDER TREES BETWEEN HOUSES AND EDGE OF PAVEMENT ON ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

AREA UNDER TREES BETWEEN HOUSES AND EDGE OF PAVEMENT ON THE EAST SIDE OF SOUTH JEFFERSON STREET FROM SOUTHEAST CORNER OF INTERSECTION OF SOUTH JEFFERSON STREET AND HIGHLAND AVENUE - South Albany Historic District, Bounded by South Jefferson Street, Highland Avenue & Whitney Avenue, Albany, Dougherty County, GA

459

Field Manual for Crack Sealing in Asphalt Pavements  

E-print Network

Field Manual for Crack Sealing in Asphalt Pavements Yetkin Yildirim, Ahmed Qatan, and Jorge Prozzi Research Project 0-4061-P3 Comparison of Hot-Poured Crack Sealant to Emulsified Asphalt Crack Sealant-4061 Comparison of Hot-Poured Crack Sealant to Emulsified Asphalt Crack Sealant Product Number 3 Field Manual

Texas at Austin, University of

460

Salt Frost Deterioration in Concrete Pavement --Causes and Mitigation  

E-print Network

Salt Frost Deterioration in Concrete Pavement --Causes and Mitigation Zhichao Liu, Will Hansen and special effects such as surface tension and osmotic effect (salt solution). ·Below the nucleation the surface contains a salt solution, pore suction attracts surface liquid and additional ice growth may

461

Nondestructive evaluation of load transfer at rigid airport pavement joints  

Microsoft Academic Search

Current design criteria for rigid pavements for commercial and military airfields assume that 25% of the load applied to an edge of a slab is transferred through the joint to an adjacent unloaded slab. A nondestructive testing technique using a falling weight deflectometer (FWD) was used to conduct field testing at a number of sites. A transfer function, developed from

Michael I. Hammons

1995-01-01

462

DEVELOPMENT OF A HYDROPHOBIC SUBSTANCE TO MITIGATE PAVEMENT ICE ADHESION  

EPA Science Inventory

The specific problem to which this report is addressed is the development of a hydrophobic substance to mitigate the adhesion of ice to pavement as an alternative to deicing chemicals. The factors involved in evaluating this concept are the following: Economics; safety; environme...

463

EVALUATION AND MITIGATION OF ASPHALT PAVEMENT TOP-DOWN CRACKING  

Microsoft Academic Search

Top-down cracking has become an asphalt surface course distress of growing concern that must be dealt with during the design, construction, maintenance, and resurfacing of long-life asphalt pavements. The surface course is designed for heavy vehicle loadings and general traffic conditions in terms of rutting, resistance, durability, noise levels, smoothness, and frictional characteristics. The surface course must be properly maintained

John J. Emery

464

Enhancing the resolution of gpr spectra for pavement engineering applications  

NASA Astrophysics Data System (ADS)

Ground Penetrating Radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. This non-destructive method uses electromagnetic radiation and detects the reflected signals from subsurface structures. It can detect objects, changes in material, and voids and cracks. GPR has many applications in a number of fields. In the field of civil engineering one of the most advanced technologies used for road pavement monitoring is based on the deployment of advanced GPR systems. One of the most relevant causes of road pavement damage is often referable to water intrusion in structural layers. In this context, GPR has been recently proposed as a method to estimate moisture content in a porous medium without preventive calibration. Hence, the development of methods to obtain an estimate of the moisture content is a crucial research field involving economic, social and strategic aspects in road safety for a great number of public and private Agencies. In particular, a recent new approach was proposed to estimate moisture content in a porous medium basing on the theory of Rayleigh scattering, showing a shift of the frequency peak of the GPR spectrum towards lower frequencies as the moisture content increases in the soil. The weakness characterizing this approach is represented by the needs of high resolution signals, whereas GPR spectra are affected by low resolution. Hence, the rising requirement for high resolution leads to specific demands for improved prediction methods. Recently, a new technique combining the response of the conventional fast Fourier transform (FFT, well known for its high-precision receiving signal level) with that of the MUSIC (multiple signal classification) algorithm, well known for its super-resolution capacity has been proposed. This combined method has been proved to obtain a high precision level in quantifying the shift of the frequency peak of the GPR spectrum. This combined method can perform a reliable coarse estimate of the (abscissa of the) frequency peak. Unfortunately, whereas resolution affecting the GPR spectra has been enhanced, we still need a sensible increasing of the moisture content to appreciate a visible frequency shift. Hence, sub-sample resolution techniques are needed to obtain a resolution better than the sample period. Addressing some of these issues, this work proposes a sub-sample resolution technique exploiting a fast parabolic interpolator, running on three samples of the GPR spectrum in the neighborhood of the frequency peak (i.e. the coarse estimation). More in details, the new detector searches for the (abscissa of the) vertex of the parabola fitted over three GPR samples: the coarse estimate of the frequency peak, and one sample before and after this estimation. The rationale behind the new fast parabolic approach is as follows. We expect the method to obtain a finer estimation of the (abscissa of the) frequency peak because we are now interpolating a parabola in the neighborhood of the same maximum (i.e the coarse estimate), but with a narrow variance thus increasing the estimation accuracy. No noteworthy increase of computational complexity and processing throughput is required to implement the new approach. In fact, near the totality of the amount of the required computation is due to the former stage (i.e. FFT and/or MUSIC implementation to evaluate the coarse estimate of the frequency peak), and the latter logic (i.e. the interpolation function) is negligible from implementation and computational point of view. Experimental results confirm the effectiveness of the proposed approach to evidence and quantify moisture content in soil. In fact, the proposed sub-sample super resolution technique can resolve a frequency shift in the GPR spectrum even for a corresponding amount of moisture less than 2-3%.

Benedetto, F.; Benedetto, A.

2012-04-01

465

AUTOMATED REAL TIME PAVEMENT MARKING RETROREFLECTIVITY MEASUREMENTS Norbert H. Maerz, University of Missouri-Rolla, 1006 Kingshighway, Rolla MO, 65409-0660, USA. Tel: (573) 341-  

E-print Network

LASERLUX® : AUTOMATED REAL TIME PAVEMENT MARKING RETROREFLECTIVITY MEASUREMENTS Norbert H. Maerz retroreflectometer is being used to measure the retroreflectivity of pavement lane markings. This vehicle-mounted retroreflectometer provides the measurements needed for proper highway pavement marking management. Quick, simple

Maerz, Norbert H.

466

Managerial perceptions of operational flexibility  

E-print Network

that cause uncertainty. Effective and efficient acquisition and construction require the proactive management of these and other uncertainties to meet performance, schedule, and cost targets. Flexibility in the form of real options can be an effective tool...

Wu, Yanzhen

2006-08-16

467

Flexible protection for metal bellows  

NASA Technical Reports Server (NTRS)

RTV silicone is used with a braided wire sheath surrounding the metal bellows in fluid transfer systems. It demonstrated best overall performance in flexibility and shock absorbing tests, high temperature, low temperature, and salt spray.

Kimble, K. G.

1970-01-01

468

Nondestructive testing of pavements and pavement bases. 1964-June, 1981 (citations from the NTIS Data Base). Report for 1964-Jun 81  

SciTech Connect

Nondestructive methods for quality assurance of pavements and pavement bases are investigated in these Government-sponsored research reports. Vibration, nuclear activation, radiometry, and acoustic detection are among the various techniques employed. (This updated bibliography contains 167 citations, 16 of which are new entries to the previous edition.)

Not Available

1981-07-01

469

Nondestructive testing of pavements and pavement bases. 1964-March 1980 (citations from the NTIS Data Base). Report for 1964-March 1980  

SciTech Connect

Nondestructive methods for quality assurance of pavements and pavement bases are investigated in these Government-sponsored research reports. Vibration, nuclear activation, radiometry, and acoustic detection are among the various techniques employed. (This updated bibliography contains 151 abstracts, 17 of which are new entries to the previous edition.)

Habercom, G.E. Jr.

1980-04-01

470

Laboratory analysis of the infiltration capacity of interlocking concrete block pavements in car parks.  

PubMed

Interlocking concrete block pavements (ICBPs) have been widely used in car parks to reduce runoff. Researches have demonstrated that clogging is the most influential factor in the reduction of the infiltration capacity of this type of permeable pavement. Nevertheless, there is no laboratory study of the infiltration performance of ICBPs that combines clogging levels with variables related with the topography of car parks such as runoff surface length (R(SL)) and surface slope (S(S)). This paper studies the infiltration behaviour of ICBP during their operational life in a car park using an improved version of the Cantabrian Fixed (CF) Infiltrometer. This laboratory device simulates direct rainfall and runoff from adjacent impervious areas over an ICBPs surface of 0.25 m(2) for different slopes (0, 3, 5, 7 and 10%) and three scenarios of clogging (surface newly built, surface clogged and surface clogged with maintenance). This paper presents the results of the tests and a statistical analysis based on three regression models (corresponding to each clogging scenario) depending on the R(SL) and S(S) variables. All models passed a confidence level of 95%, presenting high R(2) values and showing that R(SL) is a more influential variable than the S(S) for all clogging scenarios. PMID:23202575

Sañudo-Fontaneda, Luis A; Rodriguez-Hernandez, Jorge; Vega-Zamanillo, Angel; Castro-Fresno, Daniel

2013-01-01

471

Flexible Sigmoidoscopy - Gut-Check  

Cancer.gov

The combination of a flexible sigmoidoscopy with a home stool test is an effective way to look for polyps and early cancer. Polyps are small growths that could become cancer one day. The flexible sigmoidoscopy only looks at part of the colon. It requires no sedation and a relatively simple prep. The procedure can be performed by some primary care doctors and gastroenterologists, but not all doctors perform the procedure regularly.

472

Recycled materials in asphalt pavements, January 1980-June 1991 (citations from the NTIS database). Rept. for Jan 80-Jun 91  

SciTech Connect

The bibliography contains citations concerning the recycling of asphalt pavement materials, and the use of other recycled materials to manufacture asphalt pavement. Articles discuss methods used for recycling bituminous pavement including hot-mix and cold-mix. Materials used to improve recycled pavement, and recycled materials used in asphalt pavement include latexes, rubber scrap such as tires, glass shards, concretes, dusts, waste oils, roofing wastes, sulfur, and metal refining sludges. Testing and evaluation of recycled pavements both in laboratories and in test cases are considered. (The bibliography contains 75 citations.) (Also includes title list and subject index.)

Not Available

1991-06-01

473

A relation of measured deflections, pavement performance and soil characteristics  

E-print Network

98 78 $86 77 $00 75 $00 Plastieitp of Index at Tep of Subgrade Percent Ropes R ~ P, R ~ Pe RS 10 10 18 17 18 R ~ P, Reps 8 ~ Po 6 6 7 5 ~ Pe 8 9 12 7 Rd SR 64 Exes liest Exeellent hse rage Poor Poor Poor hog. -Poor...

Hanna, Daniel Nelson

1957-01-01

474

Electrodeposition of nickel sulfide on graphene-covered make-up cotton as a flexible electrode material for high-performance supercapacitors  

NASA Astrophysics Data System (ADS)

In this report, graphene nanosheets (GNS)/nickel sulfide (NiS) based material for high-performance supercapacitor is prepared by "dip and dry" and electrodeposition methods. Commercial flexible make-up cottons (MCs) are chose as skeletons to construct homogeneous three-dimensional (3D) interconnected graphene-wrapped macro-networks, which can support structures for high loading of active electrode materials and facilitate the access of electrolytes to active electrode materials. The hybrid GNS/NiS based MCs (denoted as MCs@GNS@NiS) electrode yields relatively high specific capacitance of 775 F g-1 at a charge/discharge specific current of 0.5 A g-1 and good capacitance retention of 88.1% after 1000 cycles at 2 A g-1. Furthermore, the MCs@GNS@NiS electrode delivers a high energy density of 11.2 Wh kg-1 at even a high power density of 1008 W kg-1. Therefore, such low-cost and high-performance energy MCs based on GNS/NiS hierarchical nanostructures offer great promise in large-scale energy storage device applications.

Li, Yiju; Ye, Ke; Cheng, Kui; Yin, Jinling; Cao, Dianxue; Wang, Guiling

2015-01-01

475

Three-dimensional MnO2 nanowire/ZnO nanorod arrays hybrid nanostructure for high-performance and flexible supercapacitor electrode  

NASA Astrophysics Data System (ADS)

Pure MnO2 nanowires and MnO2 nanowire/ZnO nanorod array hybrid nanostructure grown on carbon cloth are synthesized through a low temperature solution method for flexible and high performance supercapacitor applications. The MnO2 nanowire/ZnO nanorod hybrid nanostructured electrodes exhibit more than two times higher specific capacitance, and better capacitance retention than those of pure MnO2 nanowire electrodes. For the three-dimensional MnO2 nanowire/ZnO nanorod array hybrid electrode, a high specific capacitance of 746.7 F g-1 (areal capacitance ?41.5 mF cm-2) is obtained at a scan rate of 2 mV s-1, while the specific capacitance of pure MnO2 nanowire electrode is 319.6 F g-1. The electrochemical impedance spectroscopy measurements also confirm MnO2 nanowire/ZnO nanorod array hybrid electrode has better electrochemical character. The MnO2 nanowire/ZnO nanorod array hybrid electrode shows great cycle stability, it only losses 6.5% of the initial capacitance after 1000 cycles. The energy density and power density of the hybrid electrode at 2 A g-1 are 63.1 Wh kg-1 and 950 W kg-1, respectively. It is illustrated that the electrochemical performance of MnO2 nanowire electrode has been greatly enhanced with the supporting of ZnO nanorod arrays.

Li, Songzhan; Wen, Jian; Mo, Xiaoming; Long, Hao; Wang, Haoning; Wang, Jianbo; Fang, Guojia

2014-06-01

476

Performance improvement of flexible bulk heterojunction solar cells using PTB7:PC71BM by optimizing spin coating and drying processes  

NASA Astrophysics Data System (ADS)

Bulk-heterojunction solar cells were fabricated using a dichlorobenzene solution of poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b?]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) on a flexible indium-tin-oxide-coated polyethylene terephthalate substrate. It was found that the performance of the solar cells could be markedly improved by minimizing the spin coating time of a blend of PTB7 and PC71BM to 10 s and maximizing the successive drying and solidification time up to 30 min in a confined Petri dish. As a result, a short-circuit current density of 14.5 mA/cm2, an open-circuit voltage of 0.62 V, and a power conversion efficiency of 3.67% were obtained. These improvements are attributed to the growth of favorable nanostructures during the slow drying process that increased the photocarrier collection efficiency while simultaneously increasing the performance fluctuations of each device.

Ohzeki, Masaya; Fujii, Shunjiro; Arai, Yuki; Yanagidate, Tatsuki; Yanagi, Yuichiro; Okukawa, Takanori; Yoshida, Akira; Kataura, Hiromichi; Nishioka, Yasushiro

2014-02-01

477

Surface runoff from full-scale coal combustion product pavements during accelerated loading  

Microsoft Academic Search

In this study, the release of metals and metalloids from full-scale portland cement concrete pavements containing coal combustion products (CCPs) was evaluated by laboratory leaching tests and accelerated loading of full-scale pavement sections under well-controlled conditions. An equivalent of 20 years of highway traffic loading was simulated at the OSU\\/OU Accelerated Pavement Load Facility (APLF). Three types of portland cement

Chin-Min Cheng; Panuwat Taerakul; Wei Tu; Behrad Zand; Tarunjit Butalia; William Wolfe; Harold Walker

2008-01-01

478

Assessment of an Impulse GPR Antenna Abilities in Investigation of Transversal Cracks of the Bituminous Pavement  

NASA Astrophysics Data System (ADS)

Ground Penetrating Radar (GPR) technique is commonly used for detection of internal singularities of construction structure. The method is particularly efficient in the case of linear horizontal objects when profile scanning is being performed in the direction perpendicular to object elongation and polarization of the electric field is parallel to the elongation. Then the singular object manifests itself in the echogram as a scattering hyperbola. Similar response is generated by an object having shape close to a vertical half plane with horizontal edge, when the edge acts like the scattering linear object. The use of GPR technique for investigation of transversal cracks in the bituminous pavement would seem to be promising, but numerous paradoxes occur just at the beginning tests. Even well visible cracks of more than ten millimeters thickness doesn't generate noticeable GPR response, while thinner ones sometimes can produce strong response but in the deeper interior of the pavement. Thus arise a more general question: what the GPR technique can tell us about the cracks? Trying to study this problem some laboratory tests were performed to estimate efficiency of signal generation by structures simulating idealized cracks' shapes. Next long-term (several years) visual observation and repeated GPR scanning was performed on the three road sections (each one of several hundred meters length) with heavy traffic, where ongoing cracking process occurs. The preliminary measurements were directed to obtain the proper way of scanning. The main aim of the analysis was to find GPR characteristics of cracks that can be noticed on echograms. It was performed by detailed correlation of the visually observed cracks position with echograms using decimeter precision. These efforts provided a list of diagnostic GPR characteristics of cracks and some provisional scale of their intensity. In several cases the cracks were probed by drillings to recognize structures responsible for signal generation or to explain reasons of lacking signal. The three field cases represent different types of bituminous pavement and different degrees of cracking process progress, what showed first of all a large diversity GPR responses types and existence of specific masking effect related possibly to large-size granulation of the asphalt mixture. These examples show that the strong signals are frequently related to advanced deterioration in lower, older layers and confirm difficulty of cracks detection in a new cover. But on other hand long term observation showed that numerous new cracks appear on the surface in places, where some structural singularities were noticed earlier inside the new construction.

Krysi?ski, L.; Sudyka, J.

2012-04-01

479

The predictive start of hunting archer fish: a flexible and precise motor pattern performed with the kinematics of an escape C-start.  

PubMed

Once their shots have successfully dislodged aerial prey, hunting archer fish monitor the initial values of their prey's ballistic motion and elicit an adapted rapid turning maneuver. This allows these fish to head straight towards the later point of catch with a speed matched to the distance to be covered. To make the catch despite severe competition the fish must quickly and yet precisely match their turn and take-off speed to the initial values of prey motion. However, the initial variables vary over broad ranges and can be determined only after prey is dislodged. Therefore, the underlying neuronal circuitry must be able to drive a maneuver that combines a high degree of precision and flexibility at top speed. To narrow down which neuronal substrate underlies the performance we characterized the kinematics of archer fish predictive starts using digital high-speed video. Strikingly, the predictive starts show all hallmarks of Mauthner-driven teleost C-type fast-starts, which have previously not been noted in feeding strikes and were not expected to provide the high angular accuracy required. The high demands on