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1

Flexible pavement drainage monitoring, performance and stability  

Microsoft Academic Search

Pavement subsurface drainage is increasingly included in pavement designs. Typically, the subdrainage components consist of a drainage layer, edge collection system and outlet. Questions have developed relative to use of bound and unbound aggregate in the drainage layers as well as drainage layer location within the section. ^ The current study is a continuation of the study HPR-2078, “Locating the

Aiwen Feng

1999-01-01

2

A strategic laboratory approach for the performance investigation of geogrids in flexible pavements  

Microsoft Academic Search

Nowadays, the increasing request in terms of road transport makes maintenance and rehabilitation of road infrastructures key tasks for road engineering. In recent years, numerous products\\/materials have been introduced on the market and can be used in combination or singly in order to extend pavement life and guarantee high performance. Among them, geosynthetics can play different roles in pavement structures,

G. Ferrotti; F. Canestrari; A. Virgili; A. Grilli

2011-01-01

3

Permanent deformation of flexible pavements  

NASA Astrophysics Data System (ADS)

Seven pairs of pavements with granular bases were tested under controlled conditions. One pavement in each pair contained fabric inclusions. An improved testing facility was developed, including: (1) servo-hydraulic system for the loading carriage; (2) amplification and read-out system for pressure cells; (3) linearizing unit for strain coils; (4) transducers for measuring vertical and resilient deflection; (5) techniques for measuring in situ strain on fabric inclusions; (6) extensive use of nuclear density meter to monitor pavement and foundation materials. The following conclusions are drawn: (1) No improvement in performance resulted from fabric inclusions. (2) No consistent reduction in in-situ stresses, resilient strains, or permanent strains was observed as a result of fabric inclusion. (3) No consistent improvement in densities resulted from fabric inclusions. (4) Some slip apparently occurred between fabric and soil on those pavements which involved large deformations. The slip occurred between fabric and crushed limestone base rather than between fabric and silty-clay subgrade.

Brown, S. F.; Broderick, B. V.; Pappin, J. W.

1980-06-01

4

Marginal Aggregates in Flexible Pavements: Field Evaluation.  

National Technical Information Service (NTIS)

The purpose of this study was to evaluate the utilization of substandard or marginal aggregates in flexible pavement construction of airport pavements. This investigation was undertaken to evaluate the effects of using lower quality aggregates such as rou...

R. C. Ahlrich

1998-01-01

5

Flexible Layered Pavement Design Procedure for Rhode Island.  

National Technical Information Service (NTIS)

For the purpose of recommending a flexible pavement design procedure for Rhode Island using the AASHO Interim Guide, a study was made of 13 sites on selected in-service flexible pavements. Data obtained and tests performed include ADT, vehicle classificat...

V. A. Nacci K. Moultrop M. C. Wang M. T. Huston

1977-01-01

6

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

7

Geotextiles in Flexible Pavement Construction  

ERIC Educational Resources Information Center

People everywhere in the developed world regularly drive on paved roads. Learning about the construction techniques and materials used in paving benefits technology and construction students. This article discusses the use of geosynthetic textiles in pavement construction. It presents background on pavements and describes geotextiles and drainage…

Alungbe, Gabriel D.

2004-01-01

8

The effect of loading time on flexible pavement dynamic response: a finite element analysis  

NASA Astrophysics Data System (ADS)

Dynamic response of asphalt concrete (AC) pavements under moving load is a key component for accurate prediction of flexible pavement performance. The time and temperature dependency of AC materials calls for utilizing advanced material characterization and mechanistic theories, such as viscoelasticity and stress/strain analysis. In layered elastic analysis, as implemented in the new Mechanistic-Empirical Pavement Design Guide (MEPDG), the time dependency is accounted for by calculating the loading times at different AC layer depths. In this study, the time effect on pavement response was evaluated by means of the concept of “pseudo temperature.” With the pavement temperature measured from instrumented thermocouples, the time and temperature dependency of AC materials was integrated into one single factor, termed “effective temperature.” Via this effective temperature, pavement responses under a transient load were predicted through finite element analysis. In the finite element model, viscoelastic behavior of AC materials was characterized through relaxation moduli, while the layers with unbound granular material were assumed to be in an elastic mode. The analysis was conducted for two different AC mixtures in a simplified flexible pavement structure at two different seasons. Finite element analysis results reveal that the loading time has a more pronounced impact on pavement response in the summer for both asphalt types. The results indicate that for reasonable prediction of dynamic response in flexible pavements, the effect of the depth-dependent loading time on pavement temperature should be considered.

Yin, Hao; Solaimanian, Mansour; Kumar, Tanmay; Stoffels, Shelley

2007-12-01

9

Instrumentation, analysis and modeling of flexible pavement subdrainage  

Microsoft Academic Search

Pavement subsurface drainage and its effect on pavement performance has been a subject of interest since the 18$\\\\sp{\\\\rm th}$ and 19$\\\\sp{\\\\rm th}$ centuries. With no doubt the detrimental effects of heavy wheel loads on pavements with saturated base material is a significant factor. The consequence of subsurface water on pavement performance includes premature rutting, cracking, faulting, and increased roughness, all

Hossam Farouk Hassan

1996-01-01

10

Probabilistic and Adaptive Approach to Modeling Performance of Pavement Infrastructure.  

National Technical Information Service (NTIS)

Accurate prediction of pavement performance is critical to pavement management agencies. Reliable and accurate predictions of pavement infrastructure performance can save significant amounts of money for pavement infrastructure management agencies through...

Z. Li Z. Zhang

2007-01-01

11

Development of Improved Pavement Performance Prediction Models for the Indiana Pavement Management System  

Microsoft Academic Search

The Indiana Department of Transportation (INDOT) is increasingly committed to the Pavement Management System. For this reason, updated simple pavement performance prediction models with the least number of explanatory (independent) variables are required to predict the performance of various pavement types for future planning of rehabilitation or replacement. In Indiana, the two main pavement types are jointed concrete pavement (JCP)

Sedat Gulen; Karen Zhu; John Weaver; Jie Shan; William F. Flora

2001-01-01

12

Predicting Performance of Pavements by Deflection Measurements.  

National Technical Information Service (NTIS)

The two main objectives of this study are to develop a means for predicting the life of flexible pavements by use of deflection measurements of selected in-service pavements, and to determine which of the three factors of traffic, soil support, or age hav...

W. J. Liddle G. M. Jones D. E. Peterson G. F. Nielson G. Peterson

1969-01-01

13

Pavement Management 2009, Volume 1. Transportation Research Record: Journal of the Transportation Research Board, No. 2093.  

National Technical Information Service (NTIS)

This report includes 15 papers that explore the quality of automated pavement distress data collection, pavement maintenance prioritization, long-term pavement performance profile data for flexible pavements, user-oriented model for pavement funding decis...

2009-01-01

14

Pavement performance equations. Final report  

Microsoft Academic Search

The WSDOT PMS data base was used to develop regression equations for three pavement surface types: bituminous surface treatments, asphalt concrete, and portland-cement concrete. The primary regression equations developed were to predict Pavement Condition Rating (PCR) which is a measure of the pavement surface distress (ranges from 100 (no distress) to below 0 (extensive distress)). Overall, the equations fit the

J. P. Mahoney; R. K. Kay; N. C. Jackson

1988-01-01

15

Quality and timeliness in highway construction contracts: a new acceptance model based on both mechanical and surface performance of flexible pavements  

Microsoft Academic Search

Timely completion and high performance are becoming key factors in modern road projects, so research is needed to have reliable contracts and acceptance criteria. The goal of this paper is confined to the formalization and validation of a unique model for the determination of pay adjustment on the basis of both quality (mechanical and surface performance of road pavements) and

Filippo Giammaria Praticò

2007-01-01

16

Influence of mixture composition on the noise and frictional characteristics of flexible pavements  

NASA Astrophysics Data System (ADS)

Both traffic noise and wet pavement-tire friction are mainly affected by the tire/pavement interaction. Existing laboratory test methods allow for evaluation of polishing resistance of the aggregates only. Currently, there is no generally accepted standardized laboratory test method to address noise related issues and the overall frictional properties of pavements (including macrotexture). In this research, which included both laboratory and field components, friction and noise properties of the flexible (asphalt) pavements were investigated. As a part of this study, a laboratory device to polish asphalt specimens was developed and the procedure to evaluate mixture frictional properties was proposed. Following this procedure, forty-six different Superpave mixtures (each utilizing a different aggregate blends), one stone matrix asphalt (SMA) mixture and one porous friction course (PFC) mixture were tested. Six of the above mixes (four Superpave mixtures, SMA mixture and PFC mixture) were selected for laboratory noise testing. This testing was performed using a one-of-a-kind tester called the Tire/Pavement Test Apparatus (TPTA). In addition, the field sections constructed using Superpave, SMA and PFC mixtures were also periodically tested for friction and noise. Field measurements included testing of total of 23 different asphalt and two concrete pavements. The field friction testing was performed using both portable CTM and DFT devices and the (ASTM E 274) locked wheel friction trailer. The laboratory friction testing was performed using CTM and DFT devices only. The results of both field and laboratory friction measurements were used to develop an International Friction Index (IFI)-based frictional requirement for laboratory friction measurements. The results collected in the course of the study indicate that the IFI-based flag values could be successfully used in place of SN-based flag values to characterize frictional characteristics of pavements.

Kowalski, Karol J.

17

Truck fleet model for design and assessment of flexible pavements  

NASA Astrophysics Data System (ADS)

The mechanistic empirical method of flexible pavement design/assessment uses a large number of numerical truck model runs to predict a history of dynamic load. The pattern of dynamic load distribution along the pavement is a key factor in the design/assessment of flexible pavement. While this can be measured in particular cases, there are no reliable methods of predicting the mean pattern for typical traffic conditions. A simple linear quarter car model which aims to reproduce the mean and variance of dynamic loading of the truck fleet at a given site is developed here. This probabilistic model reflects the range and frequency of the different heavy trucks on the road and their dynamic properties. Multiple Sensor Weigh-in-Motion data can be used to calibrate the model. Truck properties such as suspension stiffness, suspension damping, sprung mass, unsprung mass and tyre stiffness are represented as randomly varying parameters in the fleet model. It is used to predict the statistical distribution of dynamic load at each measurement point. The concept is demonstrated by using a pre-defined truck fleet to calculate a pattern of statistical spatial repeatability and is tested by using that pattern to find the truck statistical properties that generated it.

Belay, Abraham; OBrien, Eugene; Kroese, Dirk

2008-04-01

18

Test Performance of Thermoplastic Markings on New York Concrete Pavements.  

National Technical Information Service (NTIS)

Thermoplastic centerline markings were installed at 25 sites on portland cement concrete pavement throughout New York State to evaluate their performance under various pavement and weather conditions, and to identify factors affecting their performance. T...

E. D. McNaught J. T. Capelli G. F. Gurney

1977-01-01

19

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

20

Development of a Long Range Plan for Engineering Research on Flexible Pavements.  

National Technical Information Service (NTIS)

A long range plan for engineering research on flexible pavements was developed for the U. S. Naval Civil Engineering Laboratory at Port Hueneme, California. The findings of the Navy's future needs were developed from interviews with personnel at NCEL and ...

B. M. Callaway C. R. Foster

1966-01-01

21

Design, Evaluation, and Performance of Pavements.  

National Technical Information Service (NTIS)

The 12 papers in this report deal with the following areas: The resilient modulus of subgrade reaction; finite-element model with stress-dependent support; structural model for concrete block pavement; effect of concrete shoulders on concrete pavement per...

J. A. Fischer M. R. Thompson A. M. Ioannides E. J. Barenberg A. A. A. Molenaar

1984-01-01

22

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

23

Investigating the accelerated deterioration of flexible pavement using two-stage design analysis approach  

Microsoft Academic Search

Objective  The accelerated deterioration of flexible pavement and its relation to design strength requirements is a major problem facing\\u000a highway engineers. The goal of this research is to investigate a possible relationship between the accelerated pavement deterioration\\u000a rates and pavement design strength using a two-stage design analysis approach.\\u000a \\u000a \\u000a \\u000a \\u000a Approach Overview  The approach in this study applies a two-stage solution to the three

Khaled A. Abaza; Suleiman A. Ashur

2011-01-01

24

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

25

Optimizing Construction Quality Management of Pavements Using Mechanistic Performance Analysis.  

National Technical Information Service (NTIS)

The implementation of an effective performance-based construction quality management requires a tool for determining impacts of construction quality on the life-cycle performance of pavements. This report presents a statistical-based algorithm that was de...

I. Abdallah H. Yin S. Nazarian C. Ferregut

2004-01-01

26

Asphalt Properties and Relationship to Pavement Performance: Literature Review.  

National Technical Information Service (NTIS)

The report provides a summary and analysis of information in technical literature that relates asphalt properties (both chemical and physical) to pavement performance. The review attempts to determine those properties of asphalt cement and asphalt concret...

A. Z. Durrani F. N. Finn J. S. Coplantz M. T. Yapp

1990-01-01

27

Performance Study of Continuously Reinforced Concrete Pavement on I-95.  

National Technical Information Service (NTIS)

The purpose of the study was to evaluate the performance of the CRCP on I-95. Pavement observations and measurements were made on all construction contracts and included intensive crack surveys, measurements of the widths of selected cracks, measurements ...

G. N. Shah

1978-01-01

28

Flexible Highway Pavement Design - The State of the Art. Volume I.  

National Technical Information Service (NTIS)

This report is the first of an eight-volume series which constitutes the Interim Report for PennDOT Research Project 71-7 entitled 'An Evaluation of Pennsylvania's Flexible Pavement Design Methodology.' This volume is a literature survey and critical revi...

E. S. Lindow M. G. Sharma H. Recart T. D. Larson

1973-01-01

29

Evaluation of Pavement Performance on DEL 23.  

National Technical Information Service (NTIS)

In 1994, a ramp containing two AC and two PCC sections in the SPS-8 experiment was constructed on the Ohio SHRP Test Road. In 1996, 36 more sections in the SPS-1, SPS-2 and SPS-9 experiments were opened to traffic on the mainline pavement. The response an...

S. M. Sargand

2007-01-01

30

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

31

An Annotated Bibliography and Research Review on the Development of a Long Range Plan for Engineering Research on Flexible Pavements.  

National Technical Information Service (NTIS)

An annotated bibliography and research review on Naval Civil Engineering Laboratory contract report CR 67.014 entitled 'Development of a Long Range Plan for Engineering Research on Flexible Pavements,' dated November 1966.

1966-01-01

32

Performance Related Specifications (PRS) for Concrete Pavements in Indiana, Volume 2: Technical Report  

Microsoft Academic Search

Performance-Related Specifications (PRS) are specifications that base pavement acceptance and pay adjustment on the projected performance and predicted life-cycle cost (LCC) for a specific pavement. PRS relate measurable quality characteristics with pavement performance through computer simulations that incorporate physical distress models. Previously, work at ERES consultants by Darter and co-workers developed prototype PRS for jointed plain portland cement concrete pavements

Cole Graveen; Eric Max Falker; Micah Beaver; Narayanan Neithalath; W. Jason Weiss; J. Olek; Tommy Edward Nantung; Victor Lee Gallivan

2009-01-01

33

Performance Related Specifications (PRS) for Concrete Pavements in Indiana, Volume 1: Executive Summary  

Microsoft Academic Search

Performance-Related Specifications (PRS) are specifications that base pavement acceptance and pay adjustment on the projected performance and predicted life-cycle cost (LCC) for a specific pavement. PRS relate measurable quality characteristics with pavement performance through computer simulations that incorporate physical distress models. Previously, work at ERES consultants by Darter and co-workers developed prototype PRS for jointed plain portland cement concrete pavements

Cole Graveen; Eric Max Falker; Micah Beaver; Narayanan Neithalath; W. Jason Weiss; J. Olek; Tommy Edward Nantung; Victor Lee Gallivan

2009-01-01

34

Pavement management  

SciTech Connect

The 11 papers in this report deal with the following areas: effect of pavement roughness on vehicle fuel consumption; rational seasonal load restrictions and overload permits; state-level pavement monitoring program; data requirements for long-term monitoring of pavements as a basis for development of multiple regression relations; simplified pavement management at the network level; combined priority programming of maintenance and rehabilitation for pavement networks; Arizona pavement management system: Phase 2-verification of performance prediction models and development of data base; overview of paver pavement management system; economic analysis of field implementation of paver pavement management system; development of a statewide pavement maintenance management system; and, prediction of pavement maintenance expenditure by using a statistical cost function.

Ross, F.R.; Connor, B.; Lytton, R.L.; Darter, M.I.; Shahin, M.Y.

1982-01-01

35

Effect of Concrete Shoulders on Concrete Pavement Performance.  

National Technical Information Service (NTIS)

A field program of strain and deflection measurements was conducted. The objective of the program was to evaluate the effect of frozen support, tied-concrete shoulder, and tridem-axle loading on concrete pavement performance. Results of the study on the e...

S. D. Tayabji C. G. Ball P. A. Okamoto

1983-01-01

36

Effect of Frozen Support on Concrete Pavement Performance.  

National Technical Information Service (NTIS)

A field program of strain and deflection measurements was conducted. The objective of the program was to evaluate the effect of frozen support, tied-concrete shoulder, and tridem-axle loading on concrete pavement performance. Results of the study on the e...

C. G. Ball S. D. Tayabji P. A. Okamoto

1983-01-01

37

Using Fiber-Optic Sensor Technology to Measure Strains Under the Asphalt Layer of a Flexible Pavement Structure.  

National Technical Information Service (NTIS)

In this study, a flexible pavement system was instrumented using fiber-optic strain sensors (FOSS). The purpose of this study was to demonstrate the feasibility of a FOSS installation, monitor the long-term strains under repeated traffic loading, and comp...

S. R. Sharp K. A. Galal M. E. Elfino

2006-01-01

38

Modelling the performance of pavement marking in cold weather conditions  

Microsoft Academic Search

Inadequate and poorly maintained pavement markings are considered to be one of the largest contributing factors to fatal motor vehicle crashes. As a result, it is essential to apply the appropriate pavement marking material for all weather conditions in order to increase public safety and reduce motor vehicle crashes. Building a strategic plan to renew and re-stripe pavement marking is

Hussam Fares; Khaled Shahata; Emad Elwakil; Ahmed Eweda; Tarek Zayed; Magdy Abdelrahman; Ismail Basha

2010-01-01

39

Using Pavement Performance Data to Develop Mechanistic-Empirical Concepts for Deteriorated and Rehabilitated Pavements.  

National Technical Information Service (NTIS)

This report summarizes existing pavement condition indices, and available prediction models for each condition index. This report also identifies existing data bases, where the required variables for the prediction models have been collected. Successive c...

J. S. Rao N. S. Shah G. L. Mueller M. Y. Shahin K. P. George S. M. Carpenter

1994-01-01

40

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

41

Effect of Concrete Shoulders, Lane Widening and Frozen Subgrade on Concrete Pavement Performance.  

National Technical Information Service (NTIS)

The fourth and final report of a study to determine the effect of concrete shoulders, lane widening and frozen subgrade on concrete pavement performance is presented. In this portion of the study, Falling Weight Deflectometer tests were conducted seasonal...

G. R. Korfhage

1988-01-01

42

A Guide to the Structural Design of Pavements for New Roads.  

National Technical Information Service (NTIS)

Contents: Selection of the type of pavement; Estimation of traffic for design purposes; Design life of pavements; Design of flexible pavements; Design of concrete pavements; Design of pavements with a continuously reinforced concrete base and bituminous s...

1970-01-01

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

Performance of Buried Flexible Conduits.  

National Technical Information Service (NTIS)

An extensive review was made of the performance of buried flexible culverts, with special emphasis on buckling failure modes. All known theories on elastic buckling of rings and cylinders with radial support subjected to external radial pressures were ana...

G. A. Leonards R. A. Stetkar

1978-01-01

45

Development of Empirical-Mechanistic Pavement Performance Models using Data from the Washington State PMS Database  

Microsoft Academic Search

A Pavement Management System (PMS) is a decision-support tool that aids public agencies in planning maintenance activities of their facilities. A complete PMS involves the following tasks: inspecting facilities and collecting data, predicting the deterioration of facilities through performance models, and optimizing the Maintenance, Rehabilitation, and Reconstruction (MR&R) policies over the planning horizon. Performance models are a core component of

Samer Madanat; Ziad El Nakat; Nakul Sathaye

2005-01-01

46

Evaluation of Rehabilitation Techniques for Flexible and Rigid Pavements in Nevada. Part 1. Cost-Effective Rehabilitation of Portland Cement Concrete Pavement in Nevada.  

National Technical Information Service (NTIS)

The purpose of this study, was to evaluate the feasibility of several rehabilitation strategies for Portland Cement Concrete (PCC) pavement. Recommendations were made for future crack and seat, rubblization, and reconstruction projects based on a review o...

S. Bemanian

1999-01-01

47

Water Quality Performance of Three Side-by-Side Permeable Pavement Surface Materials: Three Year Update  

EPA Science Inventory

Communities are increasingly installing structural low impact development (LID) practices to mange stormwater and reduce pollutant loads associated with stormwater runoff. Permeable pavement is a LID practice that has limited research on working-scale, side-by-side performance o...

48

Database Design for Developing Pavement Performance Equations (on CD-ROM).  

National Technical Information Service (NTIS)

A comprehensive Database Management System (DBMS) software called 'RESEARCH' was developed to manage the data which will be collected by ODOT to develop the Pavement Performance Prediction Models. This software uses 'Visual FoxPro Version 5.0, Windows' an...

1998-01-01

49

Design Specifications and Implementation Requirements for a Texas Long-Term Pavement Performance Program.  

National Technical Information Service (NTIS)

This report summarizes the requirements for development of a long-term pavement performance (LTPP) program for the state of Texas. This work is part of a project sponsored by the Texas Department of Transportation to develop distress prediction models for...

A. Saeed W. R. Hudson T. Dossey J. Weissmann

1993-01-01

50

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

51

Validation of a Three-Dimensional Finite Element Model using Airfield Pavement Multiple Wheel Load Responses  

Microsoft Academic Search

Various highway vehicle axle\\/wheel arrangements and aircraft gear configurations adopted nowadays to accommodate increasing load levels impact flexible pavement response and performance in accordance with different multiple wheel loading scenarios. As the demand for heavier wheel loads and number of load applications continually increases, it is essential to properly characterize the nonlinear behavior of the pavement subgrade and unbound aggregate

Minkwan Kim; Erol Tutumluer

2010-01-01

52

Pavement Condition Evaluation Utilizing Dynamic Deflection Measurements.  

National Technical Information Service (NTIS)

In this study, the research efforts were directed toward the development of pavement condition evaluation techniques and analysis procedures for flexible and rigid overlay pavement design. This investigation also included a detailed field evaluation of an...

K. Majidzadeh

1977-01-01

53

Western States Drainable PCC Pavement Workshop. Held in Sacramento, California on July 21-22, 1993. Summary Report.  

National Technical Information Service (NTIS)

Contents: Overview of Pavement Drainage Systems; Performance of Drainable PCC Pavements in Washington State; Arizona Experience With Concrete Pavements; Drainable PCC Pavements in Oregon; A Performance Evaluation of PCC Pavements Constructed on Permeable ...

R. Baumgardner L. Pierce G. Way L. Moore K. Smith S. Bemanian M. Farrar J. Stites G. Wells W. Nokes W. Frank J. Woodstrom

1993-01-01

54

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

55

Climate Change and the Performance of Pavement Infrastructure in Southern Canada: Context and Case Study  

Microsoft Academic Search

There is ample evidence in the engineering literature to suggest that pavement infrastructure is sensitive to climate, principally through the deterioration or deformation processes of thermal cracking, rutting, and frost heave and thaw settlement. These processes are introduced in the paper and explained within the context of pavement management. Several empirically-derived indicators, many of them used in pavement design or

Brian Mills; S. Tighe; J. Andrey; K. Huen; S. Parm

2006-01-01

56

Bituminous Pavement Polishing.  

National Technical Information Service (NTIS)

Eleven test strips containing replicate sections of bituminous pavements used in Pennsylvania were placed at the behest of a Joint Industry-PennDOT Task Force to investigate field performance of the aggregates. Fifty-two aggregate samples and 223 pavement...

S. H. Dahir W. E. Meyer

1974-01-01

57

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

58

Multiple-Wheel Heavy Gear Load Pavement Tests. Volume I. Basic Report.  

National Technical Information Service (NTIS)

Flexible and rigid pavements were constructed and tested to obtain data on pavement and soil behavior under large aircraft loadings for use in developing criteria for evaluating and designing airfield pavements subjected to multiple-wheel heavy gear loads...

A. A. Maxwell J. P. Sale R. G. Ahlvin W. J. Turnbull

1971-01-01

59

Nonwoven Geotextile Interlayers for Separating Cementitious Pavement Layers: German Practice and U.S. Field Trails.  

National Technical Information Service (NTIS)

Pavement engineering is traditionally a conservative field, but successful pavement engineers will constantly seek out proven innovative concepts with potential to improve pavement performance while reducing costs. Many pavement structures in the United S...

R. O. Rasmussen S. I. Garber

2009-01-01

60

Evaluation of MDOT's Distress Thresholds for Maintained Pavement Projects.  

National Technical Information Service (NTIS)

As an alternative to traditional contracting, pavement warranty has been adopted in Mississippi since 2000, aimed to enhance pavement performance and protect the investment in pavement construction. Currently, a manual distress survey method and the assoc...

A. El Gendy F. Wang Y. Qi

2012-01-01

61

Generating enhanced site topography data to improve permeable pavement performance assessment methods - presentation  

EPA Science Inventory

Permeable pavement surfaces are infiltration based stormwater control measures (SCM) commonly applied in parking lots to decrease impervious area and reduce runoff volume. Many are not optimally designed however, as little attention is given to draining a large enough contributin...

62

Engineering properties of resin modified pavement (RMP) for mechanistic design  

NASA Astrophysics Data System (ADS)

The research study described in this report focuses on determining the engineering properties of the resin modified pavement (RMP) material relating to pavement performance, and then developing a rational mechanistic design procedure to replace the current empirical design procedure. A detailed description of RMP is provided, including a review of the available literature on this relatively new pavement technology. Field evaluations of four existing and two new RMP project sites were made to assess critical failure modes and to obtain pavement samples for subsequent laboratory testing. Various engineering properties of laboratory-produced and field-recovered samples of RMP were measured and analyzed. The engineering properties evaluated included those relating to the material's stiffness, strength, thermal properties, and traffic-related properties. Comparisons of these data to typical values for asphalt concrete and portland cement concrete were made to relate the physical nature of RMP to more common pavement surfacing materials. A mechanistic design procedure was developed to determine appropriate thickness profiles of RMP, using stiffness and fatigue properties determined by this study. The design procedure is based on the U.S. Army Corps of Engineers layered elastic method for airfield flexible pavements. The WESPAVE computer program was used to demonstrate the new design procedure for a hypothetical airfield apron design. The results of the study indicated that RMP is a relatively stiff, viscoelastic pavement surfacing material with many of its strength and stiffness properties falling between those of typical asphalt concrete and portland cement concrete. The RMP's thermal and traffic-related properties indicated favorable field performance. The layered elastic design approach appeared to be a reasonable and practical method for RMP mechanistic pavement design, and this design procedure was recommended for future use and development.

Anderton, Gary Lee

1997-11-01

63

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

64

Investigation of Development of Pavement Roughness.  

National Technical Information Service (NTIS)

The Long-Term Pavement Performance (LTPP) program was designed as a 20-year study of pavement performance. The LTPP program consists of two programs: (1) General Pavement Studies (GPS) that use in-service test sections in either their original design phas...

C. Byrum R. W. Perera S. D. Kohn

1998-01-01

65

Locating the Drainage Layer for Bituminous Pavements in Indiana  

Microsoft Academic Search

Pavement subsurface drainage and its effect on pavement performance has been a subject of interest since the 18th and 19th centuries. With no doubt the detrimental effects of heavy wheel loads on pavements with saturated base material is a significant factor. The consequence of subsurface water on pavement performance includes premature rutting, cracking, faulting, and increased roughness, all of which

Hossam Farouk. Hassan; Thomas D. White

1996-01-01

66

Bridge and pavement maintenance  

NASA Astrophysics Data System (ADS)

Deterioration of New York State Highway structures; precast repair of continuously reinforced concrete pavement (abridgment) patching of continuously reinforced concrete pavements, evaluation of several maintenance methods for continuously reinforced concrete pavement, patching jointed concrete pavements, highway pavement repairs by using polymer concrete, pressure grouting of concrete pavements, and choosing cost-effective maintenance are discussed.

Fitzpatrick, M. W.; Law, D. A.; Dixon, W. C.; Elkins, G. E.; Mucullough, B. F.; Darter, M. I.; Yoder, E. J.; Florence, R. H., Jr.; Virkler, S. J.; McGhee, K. H.

1981-03-01

67

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...

68

Observations of Field Performance of Continuously Reinforced Concrete Pavements in Ohio.  

National Technical Information Service (NTIS)

This report documents the fact that the Chang-Majidzadeh design criteria can be used to predict crack spacing in CRC pavement structures. The Chang-Majidzadeh model is also found to be in agreement with the NCHRP proposed design criteria. The major points...

K. Majidzadeh

1978-01-01

69

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

70

Evaluation of Long-Term Pavement Performance and Noise Characteristics of Open-Graded Friction Courses - Project 2.  

National Technical Information Service (NTIS)

This report describes the second of three experimental installations of open-graded friction course (OGFC) quieter pavements designed to reduce the noise generated at the tire/pavement interface. Experimental sections of OGFC were built using asphalt rubb...

J. Weston J. S. Uhlmeyer K. W. Anderson M. Russell T. Sexton

2012-01-01

71

Flexibility and Performance of Parallel File Systems  

NASA Technical Reports Server (NTRS)

As we gain experience with parallel file systems, it becomes increasingly clear that a single solution does not suit all applications. For example, it appears to be impossible to find a single appropriate interface, caching policy, file structure, or disk-management strategy. Furthermore, the proliferation of file-system interfaces and abstractions make applications difficult to port. We propose that the traditional functionality of parallel file systems be separated into two components: a fixed core that is standard on all platforms, encapsulating only primitive abstractions and interfaces, and a set of high-level libraries to provide a variety of abstractions and application-programmer interfaces (API's). We present our current and next-generation file systems as examples of this structure. Their features, such as a three-dimensional file structure, strided read and write interfaces, and I/O-node programs, are specifically designed with the flexibility and performance necessary to support a wide range of applications.

Kotz, David; Nieuwejaar, Nils

1996-01-01

72

Monitoring and Modeling of Pavement Response and Performance. Task B: New York. Volume 1: I490, RT9A, and I86 AC Pavement.  

National Technical Information Service (NTIS)

This volume reports on experiments at three pavement sites in New York, I490 in Rochester, RT9A in New York City, and I86 near Angelica. I490 included JPCP sections instrumented to monitor loss of support from curling and warping during curing and early u...

I. S. Khoury J. Morrison S. M. Sargand

2012-01-01

73

Pavement Marking Materials.  

National Technical Information Service (NTIS)

This is a final report for a study to review and evaluate the performance of pavement marking in Colorado. The report covers the performance of materials installed transverse to the road and panel review of several long-line striping projects with higher-...

R. G. Griffin

1990-01-01

74

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

75

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

76

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.

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

2013-01-01

77

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

PubMed

In recent years, the application of titanium dioxide (TiO2) 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 TiO2 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 TiO2 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

78

Pavement Monitoring and Evaluation Issues.  

National Technical Information Service (NTIS)

Contents: Use of Seismic Pavement Analyzer in Pavement Evaluation; Nature and Detection of Void-Induced Pavement Failures; Evaluation of New Ground-Penetrating Radar Technology to Quantify Pavement Structures; Algorithms for Pavement Distress Classificati...

1995-01-01

79

Performance of Flexible Erosion Control Materials.  

National Technical Information Service (NTIS)

The objectives of the study were to determine the effect of flexible materials on the germination and growth of native grasses, as well as to determine the effectiveness of the materials to prevent erosion on typical, steep, roadside slopes before the est...

H. C. Landphair J. A. McFalls J. P. Long S. H. Godfrey

1993-01-01

80

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

81

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

82

Ground-Penetrating Radar Calibration at the Virginia Smart Road and Signal Analysis to Improve Prediction of Flexible Pavement Layer Thicknesses.  

National Technical Information Service (NTIS)

A ground-penetrating radar (GPR) system was used to collect data over the different pavement sections of the Virginia Smart Road from June 1999 until December 2002. Three antennae at different frequencies were used for this research. The collected data we...

I. L. Al-Qadi S. Lahouar A. Loulizi

2005-01-01

83

Concrete Pavement Overlays over Existing Asphalt Pavement Structures, Project Summary.  

National Technical Information Service (NTIS)

Whitetopping is a pavement system of portland cement concrete (PCC) placed on hot mix asphalt concrete (HMAC) pavement. Whitetopping is used to address distresses in asphalt pavement such as rutting and shoving. Three types of whitetopping pavements are c...

2007-01-01

84

Use of the 1993 AASHTO Guide, MEPDG and Historical Performance to Update the WSDOT Pavement Design Catalog.  

National Technical Information Service (NTIS)

This report describes the preparation of a revised pavement thickness design catalog for the Washington State Department of Transportation (WSDOT) using the 1993 American Association of State Highway and Transportation Officials (AASHTO) Guide, the Mechan...

J. Li J. P. Mahoney J. S. Uhlmeyer S. T. Muench

2011-01-01

85

Impact of Price Reductions on the Long-Term Pavement Performance of HMA Mixes in North Carolina.  

National Technical Information Service (NTIS)

Article 105-3 of the North Carolina Department of Transportation (NCDOT) Standard Specifications for Road and Structures provides guidance on price adjustments for hot mix asphalt pavements that are not within reasonably close conformity with the specific...

O. El-Haggan S. Lee Y. Seo Y. R. Kim

2005-01-01

86

On research of evaluation index system based on “white plus black” old cement concrete pavement  

Microsoft Academic Search

According to “Black Plus White” pavement bearing trength, it chooses old pavement evaluation index on the basis of “Black Plus White”, builds a blur arrangement synthetic evaluation model and methods to evaluate the old pavement synthetically. By virtue of application of actual projects, the evaluation system is convenient and flexible and it offers quick and efficient standards for the old

Yu-hong Jiang; Shou-liang Jiang; Wei Zhu

2010-01-01

87

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

88

Application of Graded Finite Elements for Asphalt Pavements  

Microsoft Academic Search

Asphalt paving layers, particularly the surface course, exhibit vertically graded material properties. This grading is caused primarily by temperature gradients and aging related stiffness gradients. Most conventional existing analysis models do not directly account for the continuous grading of properties in flexible pavement layers. As a result, conventional analysis methods may lead to inaccurate prediction of pavement responses and distress

William G. Buttlar; Glaucio H. Paulino; Seong Hyeok Song

2009-01-01

89

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

NASA Technical Reports Server (NTRS)

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.

1994-01-01

90

XACML policy performance evaluation using a flexible load testing framework  

Microsoft Academic Search

The performance and scalability of access control systems is growing more important as organisations deploy ever more complex communications and content management systems. Fine-grained access control is becoming more pervasive, so decisions are more frequent and policy sets are larger. We outline a flexible performance testing framework that accepts XACML PDP implementations (in the server component) and submits representative access

Bernard Butler; Brendan Jennings; Dmitri Botvich

2010-01-01

91

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

92

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

93

Effect of weight training on sprinting performance, flexibility and strength  

Microsoft Academic Search

Weight training has motivated and attracted the youth to develop their strength and build their muscles. Apart from developing a wholesome personality it also helps in to keep a person fit and healthy. The purpose of the study was to find out the effect of weight training (WT) on sprinting performance, flexibility and strength of the 20 students. A 45

K Azeem; A Al Ameer

2010-01-01

94

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

95

Porous pavement. Phase 1: Design and operational criteria  

NASA Astrophysics Data System (ADS)

Utilization concepts, benefits and disadvantages, as well as other characteristics of porous pavements are presented with emphasis on porous asphalt pavements, but the criteria and design approach are applicable to all other porous pavement types. Design considerations include siting problems, load bearing design and hydrologic design. The history of porous pavement development and previous experience with porous pavement by several designers, contractors and operators are described. A computer model for hydrologic performance evaluation of existing or proposed porous pavement systems is also examined. Load bearing design criteria are based on previous work conducted for porous asphalt pavements. Appendices include a sample set of specifications for porous asphalt construction and a list of soils and their permeability classes as prepared by the U.S. Soil Conservation Service.

Diniz, E. V.

1980-08-01

96

Social Performance Cues Induce Behavioral Flexibility in Humans  

PubMed Central

Behavioral flexibility allows individuals to react to environmental changes, but changing established behavior carries costs, with unknown benefits. Individuals may thus modify their behavioral flexibility according to the prevailing circumstances. Social information provided by the performance level of others provides one possible cue to assess the potential benefits of changing behavior, since out-performance in similar circumstances indicates that novel behaviors (innovations) are potentially useful. We demonstrate that social performance cues, in the form of previous players’ scores in a problem-solving computer game, influence behavioral flexibility. Participants viewed only performance indicators, not the innovative behavior of others. While performance cues (high, low, or no scores) had little effect on innovation discovery rates, participants that viewed high scores increased their utilization of innovations, allowing them to exploit the virtual environment more effectively than players viewing low or no scores. Perceived conspecific performance can thus shape human decisions to adopt novel traits, even when the traits employed cannot be copied. This simple mechanism, social performance feedback, could be a driver of both the facultative adoption of innovations and cumulative cultural evolution, processes critical to human success.

Toelch, Ulf; Bruce, Matthew J.; Meeus, Marius T. H.; Reader, Simon M.

2011-01-01

97

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

98

Degradation Modeling of Polyurea Pavement Markings.  

National Technical Information Service (NTIS)

Polyurea is a long life pavement marking material used for assets requiring long periods of uninterrupted accessibility. Knowing the performance characteristics of such markings is critical to asset management planning focused on maximizing marking materi...

J. D. Needham

2011-01-01

99

Evaluation of Bituminous Pavement with Polypropylene Fiber.  

National Technical Information Service (NTIS)

This study was conducted to evaluate the performance of a hot mix asphalt overlay modified with polypropylene fiber. In 1986, a continuously reinforced concrete pavement on Interstate 69 in Meridian, MS, was overlaid with hot mix asphalt binder and surfac...

M. Seshadri

1996-01-01

100

Pavement Thickness Surface Evenness and Construction Practice.  

National Technical Information Service (NTIS)

The structural performance and the riding quality of a road are strongly influenced by the accurate and uniform laying of the pavement materials to the appropriate design thickness. The report describes an investigation into the effectiveness of level-con...

J. C . McLellan

1982-01-01

101

Mechanistic-Empirical Pavement Design Guide Calibration for Pavement Rehabilitation.  

National Technical Information Service (NTIS)

The Oregon Department of Transportation (ODOT) is in the process of implementing the recently introduced AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) for new pavement sections. The majority of pavement work conducted by ODOT involves rehabil...

R. Shaidur R. C. Williams

2013-01-01

102

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

103

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

104

STATUS OF POROUS PAVEMENT RESEARCH  

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...

105

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

106

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

107

Using Music Performance Software with Flexible Control Interfaces for Live Performance by Severely Disabled Musicians  

Microsoft Academic Search

This paper first discusses the principles of music performance software which can map performer actions to musical output in a flexible manner. The use of the MIDIGrid and E-Scape software is described, with particular regard to work done by the Drake Music Project in facilitating music making by severely disabled performers using E-Scape. This enables musical material to be performed

Tim Anderson

1999-01-01

108

Modeling the Roughness Progression of Kansas Portland Cement Concrete (PCC) Pavements.  

National Technical Information Service (NTIS)

Long-term prediction of the performance and durability of pavement represents a critical and vital issue in the pavement surface type selection process by the Kansas Department of Transportation (KDOT) using the life-cycle-cost analysis. Accurate predicti...

M. Hossain V. Felker Y. M. Najjar

2004-01-01

109

New Jersey Experimental Pavement Project Route I-80 and I-95.  

National Technical Information Service (NTIS)

The report documents the twenty-year performance of an AASHO satellite experimental pavement project which consisted of nine test sections of various base course materials and two surface courses. The objectives in undertaking the experimental pavement pr...

R. F. Baker J. J. Quinn

1988-01-01

110

Precast Concrete Pavement for Intermittent Concrete Pavement Repair Applications  

Microsoft Academic Search

Precast pavement technology is a recently improved construction method that can be used to meet the need for rapid pavement repair and construction. Precast pavement systems are fabricated or assembled off-site, transported to the project site, and installed on a prepared foundation (existing pavement or re-graded foundation). The system components require minimal field curing time to achieve strength before opening

Shiraz Tayabji; Neeraj Buch; Erwin Kohler

111

The effects of flexibility on the performance of flapping airfoils  

NASA Astrophysics Data System (ADS)

The majority of experimental and numerical studies related to flapping flight have been exploring the relation of the thrust coefficient and propulsive efficiency to the wing geometry and kinematics. Wing flexibility has received less attention and as of today it remains unclear if it can be exploited for better performance at low-Reynolds-number flapping flight. To bridge this gap we performed simulations of a two-dimensional, two-component wings connected by a hinge with a torsional spring. The motion of the lead body has prescribed kinematics, while the trailing body motion is passive. One of the primary outcomes of this work is that nonlinear resonances play an important role in the performance of a given flapping wing system, mainly by modifying the formation of leading and trailing edge vortices. For the flexible profile used, the mean values of lift and drag forces, and the ratio of lift to drag are enhanced when the system responds in the nonlinear resonance region.

Vanella, Marcos; Fitzgerald, Tim; Preidikman, Sergio; Balaras, Elias; Balachandran, Balakumar

2007-11-01

112

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.

113

Pavement Evaluation System.  

National Technical Information Service (NTIS)

This report describes the current (1976) Air Force method for load evaluation of airfield pavements. The technique makes use of wave-propagation data and finite-element computer codes to determine the load capacity of pavements. The computer code also pro...

J. P. Nielsen G. T. Baird

1976-01-01

114

Precast concrete pavements  

NASA Astrophysics Data System (ADS)

This report reviewed published literature on precast concrete pavements and found that precast concrete pavements have had some limited application in airfields, roads, and storage areas. This review of past experience and an analytical study of precast slabs concluded that existing design and construction techniques can be adapted for use with precast concrete pavements, but more work is needed to develop effective and easily constructed load transfer designs for slab joints. Precast concrete does not offer any advantage for conventional pavements due to its high cost and surface roughness, but it may find applications for special problems such as construction in adverse weather, subgrade settlement, temporary pavements that need to be relocated, and military operations.

Rollings, R. S.; Chou, Y. T.

1981-11-01

115

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

116

STUDY ON FLOOD CONTROL PROPERTIES OF PERMEABLE PAVEMENT USING SATURATED-UNSATURATED SEEPAGE ANALYSIS  

NASA Astrophysics Data System (ADS)

The rainfall storage and infiltration facility of permeable pavement have been attracted attention as a control measure of flood and an environmental improvement measure in urban areas. However, rainfall infiltration of permeable pavement is unsteady flow and strongly dependent on the behavior of unsaturated zones in the pavement. Moreover, the wet condition of subbase course also has a great influence on the rainfall infiltration of the pavement. That's why previous studies have not made clear the precise the facility of permeable pavement as a flood control. In this paper, experimental studies and simulated analyses were performed to measure the overflow from the pavement under various conditions of rainfall intensities and estimate the rainfall infiltration of the pavement using the measurement data and unsaturated infiltration characteristics of porous asphalt materials. It is clear that this study shows the methods to have a quantitative estimation of the rainfall storage and infiltration facility of permeable pavement.

Yano, Takao; Nishiyama, Satoshi; Ohnishi, Yuzo; Nakashima, Shinichiro; Moriishi, Kazushi; Wada, Minoru

117

Studies of the effect of aging of ``quiet'' pavements on tire/pavement noise  

NASA Astrophysics Data System (ADS)

One of the issues with using quieter pavements to abate traffic noise is their continued acoustic performance over the life cycle of the surface. Aging effects can be assessed in two manners: (1) long term monitoring of the noise performance of an individual section of roadway; (2) measurement of multiple sections of pavement of the same construction, but different ages. Long term monitoring of Interstate 80 near Davis (I-80 Davis) began in 1998, just prior to the placement of a dense graded leveling course and open graded asphalt overlay. The pavement surface is now approaching 7 years old and continues to show a traffic noise reduction of about 5 dBA over the existing condition. As support of the Arizona Quiet Pavement Program (QPPP), similarly constructed sections of asphalt rubber friction course (ARFC) on Arizona's interstate highways were measured for tire/pavement performance using the close proximity (CPX) method and the on-board sound intensity method. The construction dates for the pavements ranged from 1988 to 1999. The total range in noise level was 7 dB with some indication of degrading performance with age.

Reyff, James A.; Donavan, Paul

2005-09-01

118

Performance and system flexibility of the CDF Hardware Event Builder  

SciTech Connect

The CDF Hardware Event Builder (1) is a flexible system which is built from a combination of three different 68020-based single width Fastbus modules. The system may contain as few as three boards or as many as fifteen, depending on the specific application. Functionally, the boards receive a command to read out the raw event data from a set of Fastbus based data buffers ( scanners''), reformat data and then write the data to a Level 3 trigger/processing farm which will decide to throw the event away or to write it to tape. The data acquisition system at CDF will utilize two nine board systems which will allow an event rate of up to 35 Hz into the Level 3 trigger. This paper will present detailed performance factors, system and individual board architecture, and possible system configurations.

Shaw, T.M.; Schurecht, K. (Fermi National Accelerator Lab., Batavia, IL (United States)); Sinervo, P. (Toronto Univ., ON (Canada). Dept. of Physics)

1991-11-01

119

Performance and system flexibility of the CDF Hardware Event Builder  

SciTech Connect

The CDF Hardware Event Builder [1] is a flexible system which is built from a combination of three different 68020-based single width Fastbus modules. The system may contain as few as three boards or as many as fifteen, depending on the specific application. Functionally, the boards receive a command to read out the raw event data from a set of Fastbus based data buffers (``scanners``), reformat data and then write the data to a Level 3 trigger/processing farm which will decide to throw the event away or to write it to tape. The data acquisition system at CDF will utilize two nine board systems which will allow an event rate of up to 35 Hz into the Level 3 trigger. This paper will present detailed performance factors, system and individual board architecture, and possible system configurations.

Shaw, T.M.; Schurecht, K. [Fermi National Accelerator Lab., Batavia, IL (United States); Sinervo, P. [Toronto Univ., ON (Canada). Dept. of Physics

1991-11-01

120

Pavement Base Drain Evaluation.  

National Technical Information Service (NTIS)

Portions of the Department's highway drainage system design have recently been revised. Essentially, the longitudinal drainage trench was moved closer to the pavement/shoulder joint, and the fine concrete sand layer was eliminated as a trench backfill mat...

G. L. Hoffman

1981-01-01

121

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...

122

Analysis of locomotion performance affected by flexible materials for a bionic cockroach robot  

Microsoft Academic Search

A bionic cockroach robot model is built with its coxa link made of flexible material. Locomotion performance affected by flexible material is analyzed via statics. Analysis of strain energy about flexible links is also presented through linear elastic deflections and pseudo-rigid-body models. The virtual cockroach robot model is built and the kinematic simulation is carried out by finite element and

Ronggui Song; Weihai Chen; Jianbin Zhang; Wei Wang

2009-01-01

123

Density Profiling of Asphalt Pavements.  

National Technical Information Service (NTIS)

Asphalt pavement density measurements were made using a conventional nuclear density gauge and a new electrical resistivity device called the Pavement Quality Indicator. Five sets of density tests were made at each of nine sites during, or immediately fol...

S. Shuler

2005-01-01

124

Development of Reliable Pavement Models.  

National Technical Information Service (NTIS)

The current report proposes a framework for estimating the reliability of a given pavement structure as analyzed by the Mechanistic-Empirical Pavement Design Guide (MEPDG). The methodology proposes using a previously fit response surface, in place of the ...

J. Prozzi J. P. Aguiar-Moya

2011-01-01

125

A Pavement Feedback Data System.  

National Technical Information Service (NTIS)

The complex character of highway pavements coupled with ever-increasing traffic volumes and variability of climatic conditions have made it imperative that service life data be collected and analyzed to guide the design of new and reconstructed pavements....

O. G. Strom W. R. Hudson J. L. Brown

1972-01-01

126

Pavement Management Roadmap, Executive Summary.  

National Technical Information Service (NTIS)

The Federal Highway Administration (FHWA) sponsored the development of a Pavement Management Roadmap to help identify the steps needed to address current gaps in pavement management and to establish research and development initiatives and priorities. Thi...

J. Krstulovich K. A. Zimmerman L. M. Pierce

2010-01-01

127

Development of Performance-Based Guidelines for Selection of Bituminous-Based Hot-Poured Pavement Crack Sealant: An Executive Summary Report.  

National Technical Information Service (NTIS)

This report summarizes research presented in separate technical reports, papers, and journal articles that collectively document the development of a systematic process to aid in the selection of appropriate bituminous hot-poured sealants for pavement cra...

E. Fini I. Al-Qadi J. Masson K. K. McGhee S. Yang

2009-01-01

128

Quality-Related Pay Adjustment Factors for Pavements. NCHRP Research Results Digest 371.  

National Technical Information Service (NTIS)

This digest summarizes the findings of the research conducted under NCHRP Project 10-79 to develop guidance pertaining to the quality-related pay adjustment factors used for flexible and rigid pavement construction. Highway agencies generally specify cert...

2013-01-01

129

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.

130

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

131

Functionality Enhancement of Industrialized Optical Fiber Sensors and System Developed for Full-Scale Pavement Monitoring  

PubMed Central

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.

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

2014-01-01

132

The performance impact of flexibility in the Stanford FLASH multiprocessor  

Microsoft Academic Search

Several multiprocessors have been proposed that offer programmable implementations of scal- able cache coherence as well as support for message passing. In the FLASH machine, flexibility is obtained by the use of a programmable node controller, called MAGIC, through which all transac- tions in a node pass. We use the actual code sequences that implement the cache coherence protocol, together

Mark Heinrich; Jeffrey S. Kuskin; David Ofelt; John Heinlein; Joel Baxter; Jaswinder Pal Singh; Richard Simoni; Kourosh Gharachorloo; David Nakahira; Mark A. Horowitz; Anoop Gupta; Mendel Rosenblum; John L. Hennessy

1994-01-01

133

Literature Review on Concrete Pavement Overlays Over Existing Asphalt Structures.  

National Technical Information Service (NTIS)

The primary objective of this report is to summarize the findings of the literature review on the performance of whitetopping test sections and design procedures. Two questions face pavement engineers who consider using Portland cement concrete (PCC) over...

D. H. Kim M. Won M. R. Suliman

2008-01-01

134

OC3MON: Flexible, Affordable, High Performance Staistics Collection  

Microsoft Academic Search

this paper. Initial tests with timeouts as large as 10minutes did not significantly increase the number of flows, but we have not yet tested it under heavierdata streams.This timeout-based flow definition allows flexibility in how one further specifies a flow. There are otheraspects that structure a flow specification: directionality, one sided vs. two sided, endpoint granularity,and functional layer.flow directionality: one

Joel Apisdorf; Kimberly C. Claffy; Kevin Thompson; Rick Wilder

1996-01-01

135

Mechanistic-Empirical Pavement Design Guide Implementation.  

National Technical Information Service (NTIS)

The recently introduced Mechanistic-Empirical Pavement Design Guide (MEPDG) and associated computer software provides a state-of-practice mechanistic-empirical highway pavement design methodology. The MEPDG methodology is based on pavement responses compu...

N. R. Stires R. L. Baus

2010-01-01

136

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...

137

Flexible carbon nanotube films for high performance strain sensors.  

PubMed

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

138

Performance characterization of flexible dipole rectennas for smart actuator use  

NASA Astrophysics Data System (ADS)

The concept of power transmission by a microwave is envisioned as the best option for alleviating the complexity associated with hard-wired control circuitry in controlling smart actuators and robots such as micro-aerial vehicles, biomimetic robots and space vehicles to produce remotely maneuverable capability. A flexible dipole rectenna array is conformably adaptable on the complex structure of vehicles used for practical applications of wireless power. For these applications, various flexible dipole rectennas and arrays were designed, fabricated and characterized over a frequency range of 9-12 GHz with 20 W and 200 W amplifiers through laboratory testing. The irradiance of the microwave power was measured. Also the irradiated power, the output power and the efficiency of the rectenna arrays were evaluated along with the microwave power and frequency. The maximum voltage of 65 VDC was observed from a series connected dipole rectenna array and the maximum current of 2.50 mA was obtained from a parallel connected rectenna array. The efficiency of dipole rectenna arrays ranges from 20% to 50% depending on the input power and the pole configuration. It was also demonstrated that the voltage, current and power output from a dipole rectenna array can be tailored by configuring the dipole rectenna elements in serial and parallel mode connections.

Kim, Jaehwan; Yang, Sang Yeol; Song, Kyo D.; Jones, Sean; Choi, Sang H.

2006-06-01

139

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.

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

2014-01-01

140

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...

141

High temperature performance of flexible thermal protection materials  

NASA Technical Reports Server (NTRS)

Aero convective tests of several flexible thermal protection system (FTPS) concepts were conducted in the NASA Ames Research Center 20 MW arcjet aero heating wind tunnel. The concepts consisted of quilted insulation blankets with nextel AB312 felt insulation stitched between cover cloths with AB312 thread. The cover cloths were commercially available nextel AB312 and nicalon fabrics. The specimens were subjected to convective heat fluxes ranging from 7 to 35 Btu/per sq ft per sec at stagnation pressures of .005 to .02 atm. Specimens were tested both with and without transpiration cooling. Results indicated that both the nextel and nicalon fabrics offer the potential for higher temperature applications than current FTPS, and nicalon appears to be capable of withstanding temperatures well above 2500 degrees F with minimal degradation.

Savage, R. T.; Love, W.; Bloetscher, F.

1984-01-01

142

Amorphous Oxide Semiconductors for High-Performance Flexible Thin-Film Transistors  

Microsoft Academic Search

Recently, we have demonstrated the potential of amorphous oxide semiconductors (AOSs) for developing flexible thin-film transistors (TFTs). A material exploration of AOSs desired as the channel layer in TFTs is most important for developing high-performance devices. Here, we report our concept of material exploration for AOSs in high-performance flexible and transparent TFTs from the viewpoints of chemical bonding and electronic

Kenji Nomura; Akihiro Takagi; Toshio Kamiya; Hiromichi Ohta; Masahiro Hirano; Hideo Hosono

2006-01-01

143

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

144

Rehabilitation Strategies for Highway Pavements.  

National Technical Information Service (NTIS)

NCHRP Project 1-38 was conducted to develop a process for selection of appropriate rehabilitation strategies for the ranges of pavement types and conditions found in the United States. A review of the pavement rehabilitation practices of State DOTs, and t...

C. E. Correa K. T. Hall R. P. Elliot S. H. Carpenter

2001-01-01

145

Pavement roughness and skid properties  

NASA Astrophysics Data System (ADS)

Road roughness and roadway safety as it relates to both surface and air transportation are discussed. The role of road roughness in vehicle ride, the measurement of roughness, the evaluation of riding confort, and the effect of grooving pavements are discussed. The effects of differential pavement friction on the response of cars in skidding maneuvers is discussed.

146

Automatic Pavement Distress Setection System  

Microsoft Academic Search

Statistics published by the Federal Highway Administration indicates that maintenance and rehabilitation of highway pavements in the United States requires over $17 billion a year. Conventional visual and manual pavement distress analysis approaches that the inspectors traverse the roads, stop and measure the distress objects when they are found, are very costly, time-consuming, dangerous, labor-intensive, tedious, subjective, having high degree

Heng-da Cheng; Mario Miyojim

1998-01-01

147

Long-Term Pavement Performance Materials Characterization Program: Verification of Dynamic Test Systems with an Emphasis on Resilient Modulus.  

National Technical Information Service (NTIS)

This document describes a procedure for verifying a dynamic testing system (closed-loop servohydraulic). The procedure is divided into three general phases: (1) electronic system performance verification, (2) calibration check and overall system performan...

J. L. Groeger A. Bro

2005-01-01

148

Systems approach to life-cycle design of pavements. Volume 3: LIFE2 program listing  

Microsoft Academic Search

This report is the third volume of a three-volume report which documents an automated system (LIFE2) for analyzing pavement designs and maintenance and repair strategies based on life-cycle costs. LIFE2 models existing Corps of Engineers criteria for designing rigid and flexible pavements for airfields, roads, and streets. The program includes analytical procedures for evaluating earthwork, drainage, and frost protection requirements

E. S. Lindow

1979-01-01

149

High-Performance Flexible Force and Temperature Sensing Array with a Robust Structure  

NASA Astrophysics Data System (ADS)

We have developed a flexible tactile sensor array capable of sensing physical quantities, e.g. force and temperature with high-performances and high spatial resolution. The fabricated tactile sensor consists of 8 × 8 force measuring array with 1 mm spacing and a thin metal (copper) temperature sensor. The flexible force sensing array consists of sub-millimetre-size bar-shaped semi-conductor strain gage array attached to a thin and flexible printed circuit board covered by stretchable elastomeric material on both sides. This design incorporates benefits of both materials; the semi-conductor's high performance and the polymer's mechanical flexibility and robustness, while overcoming their drawbacks of those two materials. Special fabrication processes, so called “dry-transfer technique” have been used to fabricate the tactile sensor along with standard micro-fabrication processes.

Kim, Min-Seok; Song, Han-Wook; Park, Yon-Kyu

150

Thermal Performance of Composite Flexible Blanket Insulations for Hypersonic Aerospace Vehicles  

NASA Technical Reports Server (NTRS)

This paper describes the thermal performance of a Composite Flexible Blanket Insulation (C.F.B.I.) considered for potential use as a thermal protection system or thermal insulation for future hypersonic vehicles such as the National Aerospace Plane (N.A.S.P.). Thermophysical properties for these insulations were also measured including the thermal conductivity at various temperatures and pressures and the emissivity of the fabrics used in the flexible insulations. The thermal response of these materials subjected to aeroconvective heating from a plasma arc is also described. Materials tested included two surface variations of the insulations, and similar insulations coated with a Protective Ceramic Coating (P.C.C.). Surface and backface temperatures were measured in the flexible insulations and on Fibrous Refractory Composite Insulation (F.R.C.I.) used as a calibration model. The uncoated flexible insulations exhibited good thermal performance up to 35 W/sq cm. The use of a P.C.C. to protect these insulations at higher heating rates is described. The results from a computerized thermal analysis model describing thermal response of those materials subjected to the plasma arc conditions are included. Thermal and optical properties were determined including thermal conductivity for the rigid and flexible insulations and emissivity for the insulation fabrics. These properties were utilized to calculate the thermal performance of the rigid and flexible insulations at the maximum heating rate.

Kourtides, Demetrius A.

1993-01-01

151

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

152

Balancing performance, robustness and flexibility in routing systems  

Microsoft Academic Search

Modern networks face the challenging task of handling increasingly 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 accommodating different performance goals, but also preserving

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

2010-01-01

153

A performance comparison of integration algorithms in simulating flexible structures  

NASA Technical Reports Server (NTRS)

Asymptotic formulas for the characteristic root errors as well as transfer function gain and phase errors are presented for a number of traditional and new integration methods. Normalized stability regions in the lambda h plane are compared for the various methods. In particular, it is shown that a modified form of Euler integration with root matching is an especially efficient method for simulating lightly-damped structural modes. The method has been used successfully for structural bending modes in the real-time simulation of missiles. Performance of this algorithm is compared with other special algorithms, including the state-transition method. A predictor-corrector version of the modified Euler algorithm permits it to be extended to the simulation of nonlinear models of the type likely to be obtained when using the discretized structure approach. Performance of the different integration methods is also compared for integration step sizes larger than those for which the asymptotic formulas are valid. It is concluded that many traditional integration methods, such as RD-4, are not competitive in the simulation of lightly damped structures.

Howe, R. M.

1989-01-01

154

Surface Preparation of Pavements Prior to Application of Pavement Markings.  

National Technical Information Service (NTIS)

This project was undertaken to demonstrate that surface preparation of pavements by wire brushing prior to application of traffic marking paint would result in extended service life of traffic marking paint. A brush assembly was designed, fabricated and i...

J. M. Dale

1980-01-01

155

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.

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

2014-01-01

156

Modeling of Mn/ROAD Test Sections with the CRREL Mechanistic Pavement Design Procedure.  

National Technical Information Service (NTIS)

The U.S. Army Cold Regions Research and Engineering Laboratory is developing a mechanistic pavement design procedure for use in seasonal frost areas. The procedure was used to predict pavement performance of some test sections under construction at the Mn...

S. R. Bigl R. L. Berg

1996-01-01

157

Modeling of Mn/ROAD Test Sections with the CRREL Mechanistic Pavement Design Procedure.  

National Technical Information Service (NTIS)

The U.S. Army Cold Research and Engineering Laboratoey is developing a mechanistic pavement design procedure for use in seasonal frost areas. The procedure was used to predict pavement performance of some test sections at the Mn/ROAD facility. Simulations...

S. R. Bigl R. L. Berg

1996-01-01

158

Development of a structural index for pavement management: An exploratory analysis  

Microsoft Academic Search

Knowledge of the structural condition of a highway pavement is important for pavement management at both the network level and the project level, particularly when the system monitoring, evaluation, and decision-making are to be made in a context of multiple criteria that include structural condition. A key aspect of the performance criteria for multiple criteria decision making is that the

William Fredrick Flora

2009-01-01

159

Reliability of signal processing technique for pavement damages detection and classification using ground penetrating radar  

Microsoft Academic Search

Ground penetrating radar (GPR) signal processing is a nondestructive technique, currently performed by many agencies involved in road management and particularly promising for soil characteristics interpretation. The focus of this paper is to assess the reliability of an optimal signal processing algorithm for pavement inspection. Preliminary detection and subsequent classification of pavement damages, based on an automatic GPR analysis, have

Andrea Benedetto; Francesco Benedetto; Maria Rosaria De Blasiis; Gaetano Giunta

2005-01-01

160

Evaluation of Non-Metallic Fiber Reinforced Concrete in PCC Pavements and Structures.  

National Technical Information Service (NTIS)

This interim report presents the construction and performance evaluation of four structures, namely a full-depth pavement, a thin bridge-deck overlay, a jersey barrier, and white topping on scarified asphalt pavement, constructed with a new type non-metal...

S. Kakodkar V. Ramakrishnan

1995-01-01

161

The effect of passive damping on feedback control performance of flexible manipulators  

SciTech Connect

This paper discusses the effect of passive damping on long-reach manipulators. Specifically, this paper explains how the addition of structural damping affects the closed-loop system response of the manipulators. A single-link flexible manipulator is used to illustrate the effects of passive damping on the location of the system`s pole s and zeros. The corresponding performance of the system with modified pole/zero locations is discussed. The analysis is performed including colocated and noncolocated flexible-link manipulators.

Lew, J.Y.; Evans, M.S.

1994-06-01

162

STOCHASTIC SIMULATION OF THE INFLUENCE OF RECLAIMED ASPHALT PAVEMENT MINERAL AGGREGATE VARIATION ON THE HOMOGENEITY OF RECYCLED HOT-MIX ASPHALT  

Microsoft Academic Search

Nowadays flexible pavement used for roads more and more often consists of hot mix asphalt, made in cen- tral asphalt mixing plant including granules of reclaimed asphalt pavement. The quantity of reclaimed asphalt pave- ment to be added depends on its homogeneity. The article presents the algorithm to prognosticate the mineral part composition of hot-mix asphalt, taking into consideration the

K stutis Vislavi ius; Henrikas Sivilevi

163

PCC Pavement Texturing in Illinois.  

National Technical Information Service (NTIS)

Seven textures were formed in the plastic surface of a CRC pavement during construction. They were formed using transverse tines, transverse broom, artificial turf, transverse roller, artificial turf-transverse tine combination, longitudinal broom, and lo...

J. N. Davidson

1977-01-01

164

Evaluation of Profiled Pavement Markings.  

National Technical Information Service (NTIS)

This study evaluated flat thermoplastic markings (FTM) and profiled pavement markings (PPM) installed on highways maintained by the Alabama Department of Transportation. The primary objectives of this evaluation were to compare service life, life-cycle co...

J. K. Lindly R. K. Wijesundera

2003-01-01

165

Pavement Management Surveillance Systems Evaluation.  

National Technical Information Service (NTIS)

The study evaluates available pavement distress surveillance equipment and recommends a system of proven value to the Arkansas State Highway and Transportation Department. The requirements of the system are that it be able to provide summary data for pave...

M. Bradley

1988-01-01

166

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...

167

Cumberland Gap Tunnel Pavement Problem.  

National Technical Information Service (NTIS)

The Kentucky Transportation Center was contacted by the Cumberland Gap Tunnel Authority in 2001 to conduct a Falling Weight Deflectormeter (FWD) test on the concrete pavement structure at two locations in the southbound tunnel that appeared to be settling...

B. Rister

2005-01-01

168

Stormwater quality of spring-summer-fall effluent from three partial-infiltration permeable pavement systems and conventional asphalt pavement.  

PubMed

This study examined the spring, summer and fall water quality performance of three partial-infiltration permeable pavement (PP) systems and a conventional asphalt pavement in Ontario. The study, conducted between 2010 and 2012, compared the water quality of effluent from two Interlocking Permeable Concrete Pavements (AquaPave(®) and Eco-Optiloc(®)) and a Hydromedia(®) Pervious Concrete pavement with runoff from an Asphalt control pavement. The usage of permeable pavements can mitigate the impact of urbanization on receiving surface water systems through quantity control and stormwater treatment. The PP systems provided excellent stormwater treatment for petroleum hydrocarbons, total suspended solids, metals (copper, iron, manganese and zinc) and nutrients (total-nitrogen and total-phosphorus) by reducing event mean concentrations (EMC) as well as total pollutant loadings. The PPs significantly reduced the concentration and loading of ammonia (NH4(+)+NH3), nitrite (NO2(-)) and organic-nitrogen (Org-N) but increased the concentration and loading of nitrate (NO3(-)). The PP systems had mixed performances for the treatment of phosphate (PO4(3-)). The PP systems increased the concentration of sodium (Na) and chloride (Cl) but EMCs remained well below recommended levels for drinking water quality. Relative to the observed runoff, winter road salt was released more slowly from the PP systems resulting in elevated spring and early-summer Cl and Na concentrations in effluent. PP materials were found to introduce dissolved solids into the infiltrating stormwater. The release of these pollutants was verified by additional laboratory scale testing of the individual pavement and aggregate materials at the University of Guelph. Pollutant concentrations were greatest during the first few months after construction and declined rapidly over the course of the study. PMID:24681366

Drake, Jennifer; Bradford, Andrea; Van Seters, Tim

2014-06-15

169

Aerodynamic performance of a hovering hawkmoth with flexible wings: a computational approach  

PubMed Central

Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction based analysis on the aerodynamic performance of a hovering hawkmoth, Manduca, with an integrated computational model of a hovering insect with rigid and flexible wings. Aerodynamic performance of flapping wings with passive deformation or prescribed deformation is evaluated in terms of aerodynamic force, power and efficiency. Our results reveal that wing flexibility can increase downwash in wake and hence aerodynamic force: first, a dynamic wing bending is observed, which delays the breakdown of leading edge vortex near the wing tip, responsible for augmenting the aerodynamic force-production; second, a combination of the dynamic change of wing bending and twist favourably modifies the wing kinematics in the distal area, which leads to the aerodynamic force enhancement immediately before stroke reversal. Moreover, an increase in hovering efficiency of the flexible wing is achieved as a result of the wing twist. An extensive study of wing stiffness effect on aerodynamic performance is further conducted through a tuning of Young's modulus and thickness, indicating that insect wing structures may be optimized not only in terms of aerodynamic performance but also dependent on many factors, such as the wing strength, the circulation capability of wing veins and the control of wing movements.

Nakata, Toshiyuki; Liu, Hao

2012-01-01

170

Push Can Perform Better than Pull for Flexible Manufacturing Systems with Multiple Products  

Microsoft Academic Search

We study the performance of a flexible manufacturing line producing multiple products under different material control strategies. Specifically, we compare the throughput versus average inventory characteristics when the line operates under pure pull and pure push strategies. Using simulation we show that the pure push strategy has a higher throughput for a given level of inventory than the pure pull

Ananth Krishnamurthy; Rajan Suri; Mary Vernon

2000-01-01

171

A Comparison of the Performance of Registered Nurse Students in Flexible and Traditional Clinical Courses.  

ERIC Educational Resources Information Center

An experiment was conducted at the University of Maryland at Baltimore to determine if performances would differ for registered nurses enrolled in a baccalaureate program in nursing depending on whether they participated in a flexible clinical scheduling (FLEX) program or in the traditional (non-FLEX) program. Fifty-four students took part in the…

Wolfe, Mary L.; Sands, Rosetta F.

172

Digital star scanner unit for attitude updates in space - Design flexibility and performance  

Microsoft Academic Search

The paper describes the Bendix digital star scanner unit (SSU) designed to provide moderate-to-high-accuracy attitude updates to the guidance system of a rotating space vehicle, summarizes the performance flexibility of the baseline design, and provides supporting data from a test program conducted with a prototype unit. The SSU aims at applications ranging from the detection of a limited number of

J. T. Tavolacci; C. Coscia; A. La Vaglia

1978-01-01

173

Performance of membrane compensated multirecess hydrostatic\\/hybrid flexible journal bearing system considering various recess shapes  

Microsoft Academic Search

The paper describes a theoretical study concerning the performance of an externally pressurized multirecess hydrostatic\\/hybrid flexible journal bearing system by varying the geometric shape of recess and using the membrane flow valve restrictor as a compensating element. The four different recess geometries of the bearing studied in the present study are a square recessed bearing, a circular recessed bearing, an

Narendra Singh; Satish C. Sharma; S. C. Jain; S. Sanjeeva Reddy

2004-01-01

174

Manufacturing and Performance Assessments of Several Applications of Electrotextiles and Large-Area Flexible Circuits  

Microsoft Academic Search

Numerous applications of electrotextiles and flexible circuits have been identified that can advance systems performance for many commercial, military, and aerospace devices. Several novel uses of electrotextiles have been developed for lab testing, while others have been utilized in products on the commercial market, as well as items that have flown in space. ILC Dover, Inc. has utilized conductive fibers

David P. Cadogan; Lauren S. Shook

175

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

176

High-performance flexible graphene field effect transistors with ion gel gate dielectrics.  

PubMed

A high-performance low-voltage graphene field-effect transistor (FET) array was fabricated on a flexible polymer substrate using solution-processable, high-capacitance ion gel gate dielectrics. The high capacitance of the ion gel, which originated from the formation of an electric double layer under the application of a gate voltage, yielded a high on-current and low voltage operation below 3 V. The graphene FETs fabricated on the plastic substrates showed a hole and electron mobility of 203 +/- 57 and 91 +/- 50 cm(2)/(V x s), respectively, at a drain bias of -1 V. Moreover, ion gel gated graphene FETs on the plastic substrates exhibited remarkably good mechanical flexibility. This method represents a significant step in the application of graphene to flexible and stretchable electronics. PMID:20704323

Kim, Beom Joon; Jang, Houk; Lee, Seoung-Ki; Hong, Byung Hee; Ahn, Jong-Hyun; Cho, Jeong Ho

2010-09-01

177

Analysis of Two-Layered Pavement Systems.  

National Technical Information Service (NTIS)

This report presents in detail the method of analysis used to interpret plate bearing test data using the Burmister layered pavement theory. The method is applicable to the analysis of any two-layered pavement system. (Author)

J. Nielsen

1964-01-01

178

Laser Measurement of Pavement Surface Textures.  

National Technical Information Service (NTIS)

A laboratory investigation was conducted into the feasibility of employing laser light depolarization as a measure of pavement surface textures. Pavement cores representing different conditions of wear were employed in the investigation, as were newly for...

S. Gee W. L. King

1974-01-01

179

Pavement Quality Indicators Study Five Year Report.  

National Technical Information Service (NTIS)

The Nebraska Department of Roads (NDOR) conducts annual examinations of the Nebraska's interstate and federal highway pavements. During these examinations, numerous indicators of pavement quality are measured directly or are compiled from parameters recor...

C. Kluver W. Jensen

2008-01-01

180

State of Nebraska Pavement Management Systems.  

National Technical Information Service (NTIS)

The Pavement Management System described in the following pages basically fulfills the requirements outlined in the Federal register, Vol. 58, No. 229, Paragraph 500.207. This was accomplished with the 2004 completion of the Pavement Optimization Program ...

2005-01-01

181

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...

182

Impact of pavement conditions on crash severity.  

PubMed

Pavement condition has been known as a key factor related to ride quality, but it is less clear how exactly pavement conditions are related to traffic crashes. The researchers used Geographic Information System (GIS) to link Texas Department of Transportation (TxDOT) Crash Record Information System (CRIS) data and Pavement Management Information System (PMIS) data, which provided an opportunity to examine the impact of pavement conditions on traffic crashes in depth. The study analyzed the correlation between several key pavement condition ratings or scores and crash severity based on a large number of crashes in Texas between 2008 and 2009. The results in general suggested that poor pavement condition scores and ratings were associated with proportionally more severe crashes, but very poor pavement conditions were actually associated with less severe crashes. Very good pavement conditions might induce speeding behaviors and therefore could have caused more severe crashes, especially on non-freeway arterials and during favorable driving conditions. In addition, the results showed that the effects of pavement conditions on crash severity were more evident for passenger vehicles than for commercial vehicles. These results provide insights on how pavement conditions may have contributed to crashes, which may be valuable for safety improvement during pavement design and maintenance. Readers should notice that, although the study found statistically significant effects of pavement variables on crash severity, the effects were rather minor in reality as suggested by frequency analyses. PMID:23892046

Li, Yingfeng; Liu, Chunxiao; Ding, Liang

2013-10-01

183

Environmental policy for long-life pavements  

Microsoft Academic Search

This article uses life-cycle assessment to evaluate the role of long-life pavements in achieving environmental goals. The success of such pavements in reducing environmental impacts over their life cycle hinges on their ability to serve their intended purpose for their design life. Those pavements that do serve for their entire design life offer extreme longevity at only a marginal environmental

Nicholas J. Santero; John Harvey; Arpad Horvath

2011-01-01

184

Capturing Solar Energy from Asphalt Pavements  

Microsoft Academic Search

The concept of extracting heat energy from asphalt pavements has been investigated in this study. The scope of work consisted of finite element modeling and testing with small and large scale asphalt pavement samples. Water flowing through copper tubes inserted within asphalt pavements samples were used as heat exchangers in the experiments. The rise in temperature of water as a

Rajib B. Mallick; Bao-Liang Chen; Sankha Bhowmick; Michael S. Hulen

185

Making "Magic" Sidewalks of Pervious Pavement  

NSDL National Science Digital Library

Students use everyday building materialsâsand, pea gravel, cement and waterâto 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),

186

Analysis of Load Stress for Asphalt Pavement of Lean Concrete Base  

NASA Astrophysics Data System (ADS)

The study revealed that whether it is early distresses in asphalt pavement or not depends largely on working performance of base. In the field of asphalt pavement, it is widely accepted that lean concrete base, compared with the general semi-rigid base, has better working performance, such as high strength and good eroding resistance. Problem of early distresses in asphalt pavement, which caused by more traffic loadings, can be settled effectively when lean concrete is used in asphalt pavement. Traffic loading is important parameter used in the analysis of the new pavement design. However, few studies have done extensive and intensive research on the load stress for asphalt pavement of lean concrete base. Because of that, it is necessary to study the load stress for the asphalt pavement. In the paper, first of all, three-dimension finite element model of the asphalt pavement is created for the aim of doing mechanical analysis for the asphalt pavement. And then, the two main objectives of this study are investigated. One is analysis for load stress of lean concrete base, and the other is analysis for load stress of asphalt surface. The results show that load stress of lean concrete base decreases, decrease and increase with increase of base's thickness, surface's thickness and ratio of base's modulus to foundation's modulus respectively. So far as the asphalt surface is concerned, maximum shearing stress, which is caused by load, is evident in asphalt surface which is located in transverse contraction joint of lean concrete base of asphalt pavement. Maximum shearing stress decrease, decrease, decrease and increase respectively with increase of the surface's modulus, the surface's thickness, base's thickness and ratio of base's modulus to foundation's modulus.

Lijun, Suo; Xinwu, Wang

187

Aerodynamic performance of a hovering hawkmoth with flexible wings: a computational approach.  

PubMed

Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction based analysis on the aerodynamic performance of a hovering hawkmoth, Manduca, with an integrated computational model of a hovering insect with rigid and flexible wings. Aerodynamic performance of flapping wings with passive deformation or prescribed deformation is evaluated in terms of aerodynamic force, power and efficiency. Our results reveal that wing flexibility can increase downwash in wake and hence aerodynamic force: first, a dynamic wing bending is observed, which delays the breakdown of leading edge vortex near the wing tip, responsible for augmenting the aerodynamic force-production; second, a combination of the dynamic change of wing bending and twist favourably modifies the wing kinematics in the distal area, which leads to the aerodynamic force enhancement immediately before stroke reversal. Moreover, an increase in hovering efficiency of the flexible wing is achieved as a result of the wing twist. An extensive study of wing stiffness effect on aerodynamic performance is further conducted through a tuning of Young's modulus and thickness, indicating that insect wing structures may be optimized not only in terms of aerodynamic performance but also dependent on many factors, such as the wing strength, the circulation capability of wing veins and the control of wing movements. PMID:21831896

Nakata, Toshiyuki; Liu, Hao

2012-02-22

188

How does emotion influence different creative performances? The mediating role of cognitive flexibility.  

PubMed

Cognitive flexibility is proposed to be one of the factors underlying how positive emotions can improve creativity. However, previous works have seldom set up or empirically measured an independent index to demonstrate its mediating effect, nor have they investigated its mediating role on different types of creative performances, which involve distinct processes. In this study, 120 participants were randomly assigned to positive, neutral or negative affect conditions. Their levels of cognitive flexibility were then measured by a switch task. Finally, their creative performances were calibrated by either an open-ended divergent thinking test or a closed-ended insight problem-solving task. The results showed that positive emotional states could reduce switch costs and enhance both types of creative performances. However, cognitive flexibility exhibited a full mediating effect only on the relationship between positive emotion and insight problem solving, but not between positive emotion and divergent thinking. Divergent thinking was instead more associated with arousal level. These results suggest that emotions might influence different creative performances through distinct mechanisms. PMID:24237485

Lin, Wei-Lun; Tsai, Ping-Hsun; Lin, Hung-Yu; Chen, Hsueh-Chih

2014-08-01

189

Comparative Measurements of Tire/Pavement Noise in Europe and the United States: Noise Intensity Testing in Europe (NITE) Study.  

National Technical Information Service (NTIS)

Pavements in four European countries were measured for their tire noise performance in a manner identical to that done in the States of California and Arizona. This allowed the comparison of pavements that provided a range of noise performance from quiet ...

P. R. Donavan

2006-01-01

190

Thrust performance of a flexible low-aspect-ratio pitching plate  

NASA Astrophysics Data System (ADS)

We numerically investigate the hydrodynamic performance of an elastic plate of aspect ratio 0.54 and mass ratio 0.1 that pitches around its leading edge in a free stream at Reynolds number 640. It is found that for the rigid plate and the flexible plate with the first-mode deformation, the thrust coefficient nearly collapses onto the same curve when plotted against the Strouhal number that is defined using the tail excursion. Exceptions are found when the plate is overly flexible and higher deformation modes take place. On the other hand, the flexible plate has significantly higher power efficiency than the rigid plate at the same Strouhal number. Like the rigid plate, wake transition is observed for the flexible plate as the Strouhal number is varied. Specifically, at low Strouhal numbers (St < 0.28) the wake consists of a chain of interlocked horseshoe-shape vortices; at high Strouhal numbers (St > 0.28), the wake turns into two trains of closed vortex rings with hairpin legs.

Dai, Hu; Luo, Haoxiang; de Sousa, Paulo J. S. A. Ferreira; Doyle, James F.

2012-10-01

191

A method to evaluate mechanical performance of thin transparent films for flexible displays  

Microsoft Academic Search

Mechanical flexing of plastic substrates coated with thin film permeation barriers causes stress-induced cracks that may lead to device degradation. This phenomenon is of particular importance for organic light emitting diodes, an emerging display technology that can be implemented on flexible substrates but imposes stringent requirements on the barrier performance. We demonstrate a dry-etch-based method to highlight cracks in thin

Sonia Grego; Jay Lewis; Erik Vick; Dorota Temple

2007-01-01

192

Feasibility Study on Thermal-Hydraulic Performance of Innovative Water Reactor for Flexible Fuel Cycle (FLWR)  

Microsoft Academic Search

R and D project to investigate thermal-hydraulic performance in tight-lattice rod bundles of Innovative Water Reactor for Flexible Fuel Cycle (FLWR) is started at Japan Atomic Energy Agency (JAEA) in collaboration with power company, reactor vendors, universities since 2002. The FLWR can attain the favorable characteristics such as effective utilization of uranium resources, multiple recycling of plutonium, high burn-up and

Ohnuki Akira; Takase Kazuyuki; Kureta Masatoshi; Yoshida Hiroyuki; Tamai Hidesada; Liu Wei; Nakatsuka Toru; Misawa Takeharu; Akimoto Hajime

2006-01-01

193

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

194

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

195

Porous pavement. Phase 1: Design and operational criteria  

Microsoft Academic Search

Utilization concepts, benefits and disadvantages, as well as other characteristics of porous pavements are presented with emphasis on porous asphalt pavements, but the criteria and design approach are applicable to all other porous pavement types. Design considerations include siting problems, load bearing design and hydrologic design. The history of porous pavement development and previous experience with porous pavement by several

E. V. Diniz

1980-01-01

196

Criteria for Asphalt-Rubber Concrete in Civil Airport Pavements: Mixture Design.  

National Technical Information Service (NTIS)

A mixture design procedure is developed to allow the use of asphalt-rubber binders in concrete for flexible airport pavement. The asphalt-rubber is produced by reacting asphalt with ground, scrap tire rubber to produce the binder for the asphalt-rubber co...

F. L. Roberts R. L. Lytton D. Hoyt

1986-01-01

197

Flexible and low-voltage integrated circuits constructed from high-performance nanocrystal transistors  

NASA Astrophysics Data System (ADS)

Colloidal semiconductor nanocrystals are emerging as a new class of solution-processable materials for low-cost, flexible, thin-film electronics. Although these colloidal inks have been shown to form single, thin-film field-effect transistors with impressive characteristics, the use of multiple high-performance nanocrystal field-effect transistors in large-area integrated circuits has not been shown. This is needed to understand and demonstrate the applicability of these discrete nanocrystal field-effect transistors for advanced electronic technologies. Here we report solution-deposited nanocrystal integrated circuits, showing nanocrystal integrated circuit inverters, amplifiers and ring oscillators, constructed from high-performance, low-voltage, low-hysteresis CdSe nanocrystal field-effect transistors with electron mobilities of up to 22?cm2?V-1?s-1, current modulation >106 and subthreshold swing of 0.28?V?dec-1. We fabricated the nanocrystal field-effect transistors and nanocrystal integrated circuits from colloidal inks on flexible plastic substrates and scaled the devices to operate at low voltages. We demonstrate that colloidal nanocrystal field-effect transistors can be used as building blocks to construct complex integrated circuits, promising a viable material for low-cost, flexible, large-area electronics.

Kim, David K.; Lai, Yuming; Diroll, Benjamin T.; Murray, Christopher B.; Kagan, Cherie R.

2012-11-01

198

Hovering performance of a two dimensional skeleton-reinforced flexible wing  

NASA Astrophysics Data System (ADS)

Skeleton-reinforced membrane is a typical biological design. An important application of these systems is in biolocomotion apparatus, most notably the wings of insects. The structural characteristics of the wing, a composite structure including a soft membrane reinforced by embedded skeleton(venation) is an important factor in performance of a insect flexible wing during hovering flight. To study how the structural anisotropy affects the aerodynamic performance of the deformable wing, a two-dimensional numerical study is applied to simulate the flow-structure interaction of a wing during hovering flight. In this two-dimensional rendition, the underlying veins are modeled as springs, and the membrane is modeled as a flexible plate. The effect of the wing anisotropy on lift production and power expenditure is studied for a range of veins rigidity, Reynolds number and wing inertia. It is shown that with flexible veins and the leading edge strengthening, the lift production can be significantly increased. In addition, the detailed distribution of veins stiffness in the wing has a significant effect on the unsteady flow pattern around the wing.

Shoele, Kourosh; Zhu, Qiang

2011-11-01

199

The flexible Ca-test: An improved performance in a gas permeability measurement system  

NASA Astrophysics Data System (ADS)

A flexible performance permeability measuring test for flexible organic light-emitting diodes is described in this paper. A single thin film layer of gas barriers is constructed on polyethersulfone (PES). The barrier coats the upper and lower surfaces of the PES layer. Two PES samples, one coated with Al2O3 on both surfaces and the other coated on a single surface, were made for comparison. According to this test, the time-dependent transmission curve of the one sided barrier sample had a linear slope which measured 1.65 g/m2/day at room temperature at a 50% relative humidity. This result shows that the measurement time is about 182% faster than has been achieved with the conventional test structure that uses a glass substrate. In addition, this measurement structure not only reduces the inevitable electrical noise which occurs during measurement but also increases the water vapor permeation signal. These effects improve the sensing reliability of the test. In addition, this structure is flexible, so one can instantly detect barrier performance changes when applying external stress.

Song, Eun Ho; Park, Young Wook; Choi, Jin Hwan; Park, Tae Hyun; Jeong, Jin Wook; Choi, Hyun Ju; Ju, Byeong Kwon

2011-05-01

200

Hydrodynamic analysis, performance assessment, and actuator design of a flexible tail propulsor in an artificial alligator  

NASA Astrophysics Data System (ADS)

The overall objective of this research is to develop analysis tools for determining actuator requirements and assessing viable actuator technology for design of a flexible tail propulsor in an artificial alligator. A simple hydrodynamic model that includes both reactive and resistive forces along the tail is proposed and the calculated mean thrust agrees well with conventional estimates of drag. Using the hydrodynamic model forces as an input, studies are performed for an alligator ranging in size from 1 cm to 2 m at swimming speeds of 0.3-1.8 body lengths per second containing five antagonistic pairs of actuators distributed along the length of the tail. Several smart materials are considered for the actuation system, and preliminary analysis results indicate that the acrylic electroactive polymer and the flexible matrix composite actuators are potential artificial muscle technologies for the system.

Philen, Michael; Neu, Wayne

2011-09-01

201

Performance of flexible low-Re swimmers in Newtonian and viscoelastic liquids  

NASA Astrophysics Data System (ADS)

We show experimental results of ``flexible tail'' swimmers in elastic fluids. A magnetic microswimmer powered by a frequency-controlled homogeneous magnetic field was built. Experiments were performed in a reference viscous Newtonian fluid and a glucose-based Boger fluid of the same shear viscosity. High definition video of the swimmer traveling along a channel was taken to measure its average swimming speed. We found that locomotion is enhanced in elastic fluids for most conditions. To further investigate the swimming performance, the flow field around the swimmer was visualized with a PIV (Particle Image Velocimetry) technique. The differences between Newtonian and Boger fluid will be presented and discussed.

Espinosa, J.; Zenit, R.; Lauga, E.

2011-11-01

202

Evaluation of western and eastern shale oil residua as asphalt pavement recycling agents.  

National Technical Information Service (NTIS)

The objective of this investigation was to perform a preliminary evaluation of the utility of residual materials prepared from Green River Formation (western) and New Albany Shale (eastern) shale oils as recycling agents for aged asphalt pavement. Four pe...

P. M. Harnsberger R. E. Robertson

1990-01-01

203

Portland Cement Concrete Pavement Review of QC/QA Data 2000 Through 2004.  

National Technical Information Service (NTIS)

This report analyzes the Quality Control/Quality Assurance (QC/QA) data for Portland Cement Concrete Pavement (PCCP) constructed in the years 2000 through 2004. Analysis of the overall performance of the projects was accomplished by reviewing the Calculat...

E. Chavez

2006-01-01

204

Perpetual Pavements in Texas: The Fort Worth SH 114 Project in Wise County.  

National Technical Information Service (NTIS)

The work contained in this interim report provides a case study describing the design, construction, initial structural evaluation, and performance predictions of the full-depth perpetual pavement constructed on SH 114 in the Fort Worth District. Based on...

L. F. Walubita T. Scullion

2007-01-01

205

Impact of Truck Loading on Design and Analysis of Asphaltic Pavement Structures - Phase III.  

National Technical Information Service (NTIS)

This study investigated the impact of the realistic constitutive material behavior of asphalt layer (both nonlinear inelastic and fracture) for the prediction of pavement performance. To this end, this study utilized a cohesive zone model to consider the ...

H. Ban Y. R. Kim

2012-01-01

206

Use of Time Domain Reflectometers (TDRs) in Permeable Pavement Systems to Predict Maintenance Needs and Effectiveness  

EPA Science Inventory

As the surface in permeable pavement systems clogs, infiltration capacity decreases, so maintenance is required to maintain hydrologic performance. There is limited direct guidance for determining when maintenance is needed to prevent surface runoff bypass. Research is being co...

207

Pavement Settlement Issues and Hydro-Geochemical Water Testing Results for the Cumberland Gap Tunnel.  

National Technical Information Service (NTIS)

Both Ground Penetrating Radar (GPR) surveys and Hydro-Geochemical Water Testing (HGWT) have been performed at the Cumberland Gap Tunnel to determine why the reinforced concrete pavement has settled in various areas throughout both tunnels. To date, approx...

B. Rister C. Graves J. Dinger

2010-01-01

208

Pilot Implementation of New Test Procedures for Curing in Concrete Pavements.  

National Technical Information Service (NTIS)

Curing of concrete has substantial effects on the performance of Portland cement concrete (PCC) pavement. Curing effectiveness depends on the quality of the curing materials, time of curing compound application in relation to evaporation, and the amount a...

C. Suh J. H. Yeon M. Won

2009-01-01

209

The effects of stretching on the flexibility, muscle performance and functionality of institutionalized older women.  

PubMed

Stretching has been widely used to increase the range of motion. We assessed the effects of a stretching program on muscle-tendon length, flexibility, torque, and activities of daily living of institutionalized older women. Inclusion/exclusion criteria were according to Mini-Mental State Examination (MMSE) (>13), Barthel Index (>13) and Lysholm Scoring Scale (>84). Seventeen 67 ± 9 year-old elderly women from a nursing home were divided into 2 groups at random: the control group (CG, N = 9) participated in enjoyable cultural activities; the stretching group (SG, N = 8) performed active stretching of hamstrings, 4 bouts of 1 min each. Both groups were supervised three times per week over a period of 8 weeks. Peak torque was assessed by an isokinetic method. Both groups were evaluated by a photogrammetric method to assess muscle-tendon length of uni- and biarticular hip flexors and hamstring flexibility. All measurements were analyzed before and after 8 weeks by two-way ANOVA with the level of significance set at 5%. Hamstring flexibility increased by 30% in the SG group compared to pre-training (76.5 ± 13.0° vs 59.5 ± 9.0°, P = 0.0002) and by 9.2% compared to the CG group (76.5 ± 13.0° vs 64.0 ± 12.0°, P = 0.0018). Muscle-tendon lengths of hip biarticular flexor muscles (124 ± 6.8° vs 118.3 ± 7.6°, 5.0 ± 7.0%, P = 0.031) and eccentric knee extensor peak torque were decreased in the CG group compared to pre-test values (-49.4 ± 16.8 vs -60.5 ± 18.9 Nm, -15.7 ± 20%, P = 0.048). The stretching program was sufficient to increase hamstring flexibility and a lack of stretching can cause reduction of muscle performance. PMID:21399855

Gallon, D; Rodacki, A L F; Hernandez, S G; Drabovski, B; Outi, T; Bittencourt, L R; Gomes, A R S

2011-03-01

210

The Concrete and Pavement Challenge  

ERIC Educational Resources Information Center

The modern world is characterized by the extensive use of concrete and asphalt pavement. Periodically, these materials are replaced and the old materials disposed of. In this challenge, students will be asked to develop ways to reuse the old materials. It is important for students to understand how concrete and asphalt are made and applied, as…

Roman, Harry T.

2012-01-01

211

A Methodology to Estimate Load and Non-Load Shares of Highway Pavement Routine Maintenance and Rehabilitation Expenditures  

Microsoft Academic Search

The present study focused on the estimation of load and non-load shares of pavement maintenance and rehabilitation expenditures. The information provides the basis for the allocation of pavement-related expenditures in a highway cost allocation study. A comprehensive database was developed in the study, and an aggregate performance approach was used based on econometric models. This approach utilizes the marginal effect

Zongzhi Li; Kumares C. Sinha

2000-01-01

212

Electrochromic performance of PECVD-synthesized WO xC y thin films on flexible PET\\/ITO substrates for flexible electrochromic devices  

Microsoft Academic Search

Electrochromic performance of WOxCy films deposited onto 60?\\/? flexible PET (polyethylene terephthalate)\\/ITO (indium tin oxide) substrates by low temperature plasma-enhanced chemical vapor deposition (PECVD) was investigated. It was proven that extraordinary electrochromic performance was provided when the precursor [tungsten carbonyl, W(CO)6; TC] vapor, carried by argon gas, was mixed with air gas and synthesized by radio frequency (r.f.) power at

Yung-Sen Lin; Hsuan-Ta Chen; Jhe-Yi Lai

2009-01-01

213

High performance dual-wave mode flexible surface acoustic wave resonators for UV light sensing  

NASA Astrophysics Data System (ADS)

Dual-mode flexible ZnO/polyimide surface acoustic wave (SAW)-based ultraviolet (UV) light sensors were fabricated and their performance was investigated. UV light sensing measurements showed that the responses of the dual wave modes of the sensors increase with the increase of light intensity and the frequency changes linearly with the change of light intensity. Under a 4.5 mW cm?2 UV light illumination, the resonant frequency of the Rayleigh wave decreased up to ?43 kHz, while that of the Lamb wave was approximately 76 kHz. The UV light sensitivities for the two resonant modes are 111.3 and 55.8 ppm (mW cm?2)–1, respectively. The resonant frequency, phase angle and amplitude of the two resonant modes exhibited a good repeatability in responding to cyclic change of the UV light, and an excellent stability up to a long duration of UV light exposure. The dual-mode flexible SAW resonators are simple in structure, more accurate in detection, and can be fabricated at low cost are, therefore, very promising for application in flexible sensors and electronics.

He, X. L.; Zhou, J.; Wang, W. B.; Xuan, W. P.; Yang, X.; Jin, H.; Luo, J. K.

2014-05-01

214

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

215

Perpetual Pavement Instrumentation for the Marquette Interchange Project Phase 1.  

National Technical Information Service (NTIS)

This report provides details on the design, installation and monitoring of a pavement instrumentation system for the analysis of load-induced stresses and strains within a perpetual hot mix asphalt (HMA) pavement system. The HMA pavement was constructed a...

D. E. Newman J. A. Crovetti J. P. Schabelski N. J. Hornyak

2007-01-01

216

Effective Pavement Marking Practices for Sealcoat and Hot-Mix Asphalt Pavements.  

National Technical Information Service (NTIS)

This report describes the tasks of research conducted to identify effective pavement marking practices for seal coat and hot-mix asphalt (HMAC) pavements in Texas. The researchers reviewed literature, determined current Texas Department of Transportation ...

T. J. Gates H. G. Hawkins E. R. Rose

2003-01-01

217

High performance and flexible FPGA-based time shared optical network (TSON) metro node.  

PubMed

The paper presents the architecture, implementation and evaluation of the flexible and finely granular Time Shared Optical Network (TSON) metro node. It focuses on the FPGA-based Layer 2 TSON metro node system. The experimentally measured results show exceptional performance of up to 8.68 Gbps throughput per 10 Gbps port, 95.38% of theoretical maximum throughput, latency of less than 160 ?sec and jitter of less than 25 ?sec. The TSON topology agnostic node/network also delivers differentiated QoS latency levels yet always guaranteed (contention-free) by deploying diverse time-slice allocation schemes. PMID:23482121

Yan, Yan; Zervas, Georgios; Qin, Yixuan; Rofoee, Bijan R; Simeonidou, Dimitra

2013-03-11

218

Automated management for pavement inspection system (AMPIS)  

NASA Astrophysics Data System (ADS)

An automated in-situ road surface distress surveying and management system, AMPIS, has been developed on the basis of video images within the framework of GIS software. Video image processing techniques are introduced to acquire, process and analyze the road surface images obtained from a moving vehicle. ArcGIS platform is used to integrate the routines of image processing and spatial analysis in handling the full-scale metropolitan highway surface distress detection and data fusion/management. This makes it possible to present user-friendly interfaces in GIS and to provide efficient visualizations of surveyed results not only for the use of transportation engineers to manage road surveying documentations, data acquisition, analysis and management, but also for financial officials to plan maintenance and repair programs and further evaluate the socio-economic impacts of highway degradation and deterioration. A review performed in this study on fundamental principle of Pavement Management System (PMS) and its implementation indicates that the proposed approach of using GIS concept and its tools for PMS application will reshape PMS into a new information technology-based system providing a convenient and efficient pavement inspection and management.

Chung, Hung Chi; Girardello, Roberto; Soeller, Tony; Shinozuka, Masanobu

2003-08-01

219

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

220

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

221

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

222

Manganese pavements on the blake plateau.  

PubMed

Dredge samples and photographs from the Blake Plateau, off the southeast coast of the United States, indicate that a layer of manganese oxide forms pavement that may be continuous over an area af about 5000 square kilometers. The manganese pavement grades into round manganese nodules to the south and east and into phosphate nodules to the west. The Gulf Stream probably maintains a very unusual environment that prohibits deposition of clastic sediment and permits accretion of manganese pavements. PMID:17739590

Pratt, R M; McFarlin, P F

1966-03-01

223

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

224

Flexible nanocrystal-coated glass fibers for high-performance thermoelectric energy harvesting.  

PubMed

Recent efforts on the development of nanostructured thermoelectric materials from nanowires (Boukai, A. I.; et al. Nature 2008, 451, (7175), 168-171; Hochbaum, A. I.; et al. Nature 2008, 451, (7175), 163-167) and nanocrystals (Kim, W.; et al. Phys. Rev. Lett. 2006, 96, (4), 045901; Poudel, B.; et al. Science 2008, 320, (5876), 634-638; Scheele, M.; et al. Adv. Funct. Mater. 2009, 19, (21), 3476-3483; Wang, R. Y.; et al. Nano Lett. 2008, 8, (8), 2283-2288) show the comparable or superior performance to the bulk crystals possessing the same chemical compositions because of the dramatically reduced thermal conductivity due to phonon scattering at nanoscale surface and interface. Up to date, the majority of the thermoelectric devices made from these inorganic nanostructures are fabricated into rigid configuration. The explorations of truly flexible composite-based flexible thermoelectric devices (See, K. C.; et al. Nano Lett. 2010, 10, (11), 4664-4667) have thus far achieved much less progress, which in principle could significantly benefit the conversion of waste heat into electricity or the solid-state cooling by applying the devices to any kind of objects with any kind of shapes. Here we report an example using a scalable solution-phase deposition method to coat thermoelectric nanocrystals onto the surface of flexible glass fibers. Our investigation of the thermoelectric properties yields high performance comparable to the state of the art from the bulk crystals and proof-of-concept demonstration also suggests the potential of wrapping the thermoelectric fibers on the industrial pipes to improve the energy efficiency. PMID:22409308

Liang, Daxin; Yang, Haoran; Finefrock, Scott W; Wu, Yue

2012-04-11

225

Flexible pillared graphene-paper electrodes for high-performance electrochemical supercapacitors.  

PubMed

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. PMID:22162371

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

2012-02-01

226

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

227

Electrochromic performance of NiV x O y thin films deposited onto flexible PET\\/ITO substrates by reactive plasma sputtering for flexible electrochromic devices  

Microsoft Academic Search

An investigation was conducted on the electrochromic properties of plasma sputtered-nickel–vanadium oxide thin films on 40?\\/? flexible polyethylene terephthalate\\/indium tin oxide substrates. Metallic Ni0.93V0.07 target, sputtered by radio frequency power with argon gases and reacted with oxygen gases at room temperature (23°C), was proven to provide extraordinary electrochromic performance. Cyclic voltammetry switching measurements found that only low driving voltages from

Y.-S. Lin; P.-W. Chen; D.-J. Lin

2010-01-01

228

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

229

Performance limitations of joint variable-feedback controllers due to manipulator structural flexibility  

NASA Technical Reports Server (NTRS)

The performance limitations of manipulators under joint variable-feedback control are studied as a function of the mechanical flexibility inherent in the manipulator structure. A finite-dimensional time-domain dynamic model of a two-link two-joint planar manipulator is used in the study. Emphasis is placed on determining the limitations of control algorithms that use only joint variable-feedback information in calculations of control decisions, since most motion control systems in practice are of this kind. Both fine and gross motion cases are studied. Results for fine motion agree well with previously reported results in the literature and are also helpful in explaining the performance limitations in fast gross motions.

Cetinkunt, Sabri; Book, Wayne J.

1990-01-01

230

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

231

A quantitative performance measure for a clinical evaluation of comb structure removal algorithms in flexible endoscopy  

NASA Astrophysics Data System (ADS)

Modern techniques for technical inspection as well as medical diagnostics and therapy in keyhole-surgery scenarios make use of flexible endoscopes. Common to both application fields are very small natural or manmade entry points to the observed scene, as well as the complexity of the hollow itself. These make the use of rigid lens-based endoscopes or tip chip videoscopes impossible. Due to the fact that the fiber-optic image guide of a flexible endoscope introduces a comb structure to the acquired images, many research has been devoted to algorithms for an effective removal of such artifacts. Oftentimes, this research has been motivated by the fact, that the comb structure prevents an application of some well-established methods offered by the computer vision and image processing community. Unfortunately, the performance of the presented approaches are commonly visually evaluated or with respect to proprietary, non-standardized metrics. Thus, the performances of individual algorithms are hard to compare with each other. For this reasons, we propose a performance measure for fiber-optic imaging devices that has been motivated by the physics of optics. In this field, an optical system is frequently described by linear systems theory and the system's quality can be expressed by its transfer function. The determination of this transfer function has been standardized by the ISO for lens based imaging systems and represents a widely accepted measure for the quality of such systems. In this contribution, we present methods that account for fiber-optic imaging systems and thus enable a standardized performance evaluation. Finally, we demonstrate its use by comparing two recent state of the art comb structure removal algorithms, each of them being a representative of a spatial and a frequency domain method, respectively.

Rupp, Stephan

2008-04-01

232

Flexible and binder-free organic cathode for high-performance lithium-ion batteries.  

PubMed

Fabrication of a flexible organic -electrode by growing polyimide nanoflakes on single-wall carbon nanotube films is presented. The flexible electrode exhibits high capacity and outstanding rate -capability. This electrode is promising for the application in high-power flexible -lithium-Ion batteries. PMID:24619966

Wu, Haiping; Shevlin, Stephen A; Meng, Qinghai; Guo, Wei; Meng, Yuena; Lu, Kun; Wei, Zhixiang; Guo, Zhengxiao

2014-05-01

233

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

234

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

235

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

236

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

237

Reducing traffic noise with quieter pavements  

Microsoft Academic Search

In recent years, interest has increased in the use of pavement type to reduce traffic noise. This has been driven by public concern over noise from freeways and state transportation agencies' interest in using pavement instead of sound walls to mitigate traffic noise. Beginnings of the recent interest go back to 1998 with the formation of the Institute for Safe,

Paul Donavan

2005-01-01

238

Laboratory investigation of portland cement concrete containing recycled asphalt pavements  

Microsoft Academic Search

Recycled asphalt pavement (RAP) is the removed and\\/or reprocessed pavement material containing asphalt and aggregate. The use of RAP in asphalt pavement has become a common practice in the construction of new, and reconstruction of old, hot mix asphalt (HMA) pavements. But little research has been done to examine the potential of incorporating RAP into concrete. Since RAP contains asphalt,

Baoshan Huang; Xiang Shu; Guoqiang Li

2005-01-01

239

QUANTIFICATION OF THE IMPACT OF SUBGRADE SWELLING IN PAVEMENT DESIGN  

Microsoft Academic Search

Accurate prediction of the impact of environmental factors on pavement serviceability is important for a pavement design. In this regard, AASHTO Pavement Design Guidelines (1986) provide a rational method of incorporating the effects of roadbed swelling and frost action. According to the AASHTO (1986) procedure, the present serviceability index (PSI) loss of a pavement segment due to environmental factors is

1996-01-01

240

PAVEMENT DAMAGE FROM TRANSIT BUSES AND MOTOR COACHES  

Microsoft Academic Search

This paper investigates the load-associated pavement damage effects of transit and intercity (motor coaches) buses operating on urban and rural interstate highway systems. The paper presents analyses of (i) the effect of pavement surface roughness on pavement damage potential from transit and intercity buses with different lengths, (ii) the effects of changes in the weights of transit buses on pavement

Edward Fekpe

241

Study of image-based pavement cracking measurement techniques  

Microsoft Academic Search

Cracking is one of the most common diseases that happen to the pavement and a field cracking survey and a forensic investigation are important work for preventive maintenance. In order to measure the pavement crackings automatically, this paper uses digital image processing techniques to process the pavement cracking images acquired by the digital camera and classify the pavement cracking types

Sun Zhaoyun; Wang Chaofan; Sha Aimin

2009-01-01

242

An application of smart dust for pavement condition monitoring  

NASA Astrophysics Data System (ADS)

Pavement maintenance is vital for travel safety; detecting road weather conditions using a wireless sensing network poses many challenges due to the harsh environment. This paper presents some preliminary results of an ongoing effort of applying "Smart Dust" sensor network for monitoring pavement temperature and moisture condition to detect icy road condition. Careful considerations yield effective solutions to various hardware and software development issues including the selection of sensors and antenna, design of casing, interfacing motes with alien sensors and programming of motes. A series of experiments is carried out to study traffic interference to packet delivery performance of a small-scale sensor network in a pseudo-field environment. In addition, several overnight tests are conducted to study the performance of motes operated under a power efficient condition. The results are analyzed and challenges are identified in this smart sensing application. The aforementioned research activities would benefit robust real-world implementations of off-the-shelf sensor network products.

Ferzli, Nadim A.; Ivey, Richard A.; King, Timothy; Sandburg, Colby J.; Pei, Jin-Song; Zaman, Musharraf M.; Refai, Hazem H.; Lin, Hung, Jr.; Landrum, Aaron; Victor, Rory

2006-04-01

243

Pavement roughness monitoring method using fiber optic vibration sensors  

NASA Astrophysics Data System (ADS)

Fiber optic sensor system, which is not corrosible semi-permanent, no influence by electromagnetic waves, and able to multiplex, can be expect to take an important part to assess the safety and residual estimate the life span of the highway pavement structure. In this research, as in situ monitoring of roughness of pavement, we propose the vibration monitoring method using fiber optic sensors. We designed and produced prototype fiber optic vibration sensor packages. Laboratory impact tests with the sensors were performed. The sensors showed very good responsibility to the impact and nice damping shape like other ordinary accelerometers. Actual road tests with the prototype vibration sensor were also performed. The ambient vibration by the vehicles was used for the experiment.

Kim, Ki-Soo; Baek, Yong; Yoo, In Kyoon

2010-03-01

244

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

245

Parametric study of the swimming performance of a fish robot propelled by a flexible caudal fin.  

PubMed

In this paper, we aim to study the swimming performance of fish robots by using a statistical approach. A fish robot employing a carangiform swimming mode had been used as an experimental platform for the performance study. The experiments conducted aim to investigate the effect of various design parameters on the thrust capability of the fish robot with a flexible caudal fin. The controllable parameters associated with the fin include frequency, amplitude of oscillation, aspect ratio and the rigidity of the caudal fin. The significance of these parameters was determined in the first set of experiments by using a statistical approach. A more detailed parametric experimental study was then conducted with only those significant parameters. As a result, the parametric study could be completed with a reduced number of experiments and time spent. With the obtained experimental result, we were able to understand the relationship between various parameters and a possible adjustment of parameters to obtain a higher thrust. The proposed statistical method for experimentation provides an objective and thorough analysis of the effects of individual or combinations of parameters on the swimming performance. Such an efficient experimental design helps to optimize the process and determine factors that influence variability. PMID:21068469

Low, K H; Chong, C W

2010-12-01

246

Pavement roughness evaluations using a Mays Ride Meter  

NASA Astrophysics Data System (ADS)

Roughness data on new pavement construction and recent resurfacings is analyzed and an acceptance procedure for resurfacing developed. A high-speed measurement device known as the Mays ride meter was used for much of the roughness testing. The Mays meter consists of instrumentation mounted in a passenger car which measures smoothness in terms of the relative motion between the car body and axle. Smoothness tests performed on new freeways indicate that the overall rideability of our bituminous pavements has improved substantially, a "Good' rating being typical. Rolling straightedge-based smoothness acceptance provisions were adopted to deal with the isolated instances of unacceptable riding quality which continue to be observed. Data from several new concrete projects indicate a small, yet significant relative improvement in rideability.

Croteau, J. R.

1981-06-01

247

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

248

AN OPTIMAL MAINTENANCE MANAGEMENT MODEL FOR AIRPORT CONCRETE PAVEMENT  

NASA Astrophysics Data System (ADS)

In this paper, an optimal management model is formulated for the performance-based rehabilitation/maintenance contract for airport concrete pavement, whereby two types of life cycle cost risks, i.e., ground consolidation risk and concrete depreciation risk, are explicitly considered. The non-homogenous Markov chain model is formulated to represent the deterioration processes of concrete pavement which are conditional upon the ground consolidation processes. The optimal non-homogenous Markov decision model with multiple types of risk is presented to design the optimal rehabilitation/maintenance plans. And the methodology to revise the optimal rehabilitation/maintenance plans based upon the monitoring data by the Bayesian up-to-dating rules. The validity of the methodology presented in this paper is examined based upon the case studies carried out for the H airport.

Shimomura, Taizo; Fujimori, Yuji; Kaito, Kiyoyuki; Obama, Kengo; Kobayashi, Kiyoshi

249

Thrust performance and wake structure of a pitching flexible plate at low aspect ratio  

NASA Astrophysics Data System (ADS)

Thrust performance and wake structure are numerically investigated for a rectangular plate (AR = 0.54) that pitches around the leading edge in a free stream. The plate is flexible and it may undergo large displacement. The simulations employ a newly developed fluid-structure-interaction code based on a sharp-interface immersed boundary solver for the flow and a nonlinear finite-element solver for the elastic plate. Implemented on a Cartesian mesh, the flow solver allows us to capture the vortex dynamics of the wake accurately and efficiently. The mass ratio of the plate is low so that the deformation is solely caused by the hydrodynamic force. The results will be compared with the experimental result for the rigid plate from Buchholz and Smits (J Fluid Mech 603, 2008). Both the thrust level and power efficiency will be used to evaluate the performance of the plate, and the results will be compared with those for the corresponding rigid plate with the same effective pitching angle. The effect of the active pitching angle, the bending rigidity, and the Strouhal number will be presented.

Ferreira de Sousa, Paulo; Dai, Hu; Luo, Haoxiang; Doyle, James

2010-11-01

250

Pavement distress detection and severity analysis  

NASA Astrophysics Data System (ADS)

Automatic recognition of road distresses has been an important research area since it reduces economic loses before cracks and potholes become too severe. Existing systems for automated pavement defect detection commonly require special devices such as lights, lasers, etc, which dramatically increase the cost and limit the system to certain applications. Therefore, in this paper, a low cost automatic pavement distress evaluation approach is proposed. This method can provide real-time pavement distress detection as well as evaluation results based on the color images captured from a camera installed on a survey vehicle. The entire process consists of two main parts: pavement surface extraction followed by pavement distress detection and classification. In the first part, a novel color segmentation method based on a feed forward neural network is applied to separate the road surface from the background. In the second part, a thresholding technique based on probabilistic relaxation is utilized to separate distresses from the road surface. Then, by inputting the geometrical parameters obtained from the detected distresses into a neural network based pavement distress classifier, the defects can be classified into different types. Simulation results are given to show that the proposed method is both effective and reliable on a variety of pavement images.

Salari, E.; Bao, G.

2011-02-01

251

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

252

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

253

‘Bucky gel’ of multiwalled carbon nanotubes as electrodes for high performance, flexible electric double layer capacitors  

NASA Astrophysics Data System (ADS)

We report the preparation of a gelled form of multiwalled carbon nanotubes (MWCNTs) with an ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethane sulfonyl)imide (BMPTFSI)), referred to as ‘bucky gel’, to be used as binderless electrodes in electrical double layer capacitors (EDLCs). The characteristics of gelled MWCNTs are compared with pristine MWCNTs using transmission electron microscopy, x-ray diffraction and Raman studies. A gel polymer electrolyte film consisting of a blend of poly(vinylidene fluoride-co-hexafluoropropylene) and BMPTFSI, exhibiting a room temperature ionic conductivity of 1.5 × 10-3 S cm-1, shows its suitability as an electrolyte/separator in flexible EDLCs. The performance of EDLCs, assembled with bucky gel electrodes, using impedance spectroscopy, cyclic voltammetry and charge-discharge analyses, are compared with those fabricated with pristine MWCNT-electrodes. An improvement in specific capacitance (from 19.6 to 51.3 F g-1) is noted when pristine MWCNTs are replaced by gelled MWCNT-binderless electrodes. Although the rate performance of the EDLCs with gelled MWCNT-electrodes is reduced, the pulse power of the device is sufficiently high (˜10.5 kW kg-1). The gelled electrodes offer improvements in energy and power densities from 2.8 to 8.0 Wh kg-1 and 2.0 to 4.7 kW kg-1, respectively. Studies indicate that the gel formation of MWCNTs with ionic liquid is an excellent route to obtain high-performance EDLCs.

Singh, Manoj K.; Kumar, Yogesh; Hashmi, S. A.

2013-11-01

254

'Bucky gel' of multiwalled carbon nanotubes as electrodes for high performance, flexible electric double layer capacitors.  

PubMed

We report the preparation of a gelled form of multiwalled carbon nanotubes (MWCNTs) with an ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethane sulfonyl)imide (BMPTFSI)), referred to as 'bucky gel', to be used as binderless electrodes in electrical double layer capacitors (EDLCs). The characteristics of gelled MWCNTs are compared with pristine MWCNTs using transmission electron microscopy, x-ray diffraction and Raman studies. A gel polymer electrolyte film consisting of a blend of poly(vinylidene fluoride-co-hexafluoropropylene) and BMPTFSI, exhibiting a room temperature ionic conductivity of 1.5 × 10(-3) S cm(-1), shows its suitability as an electrolyte/separator in flexible EDLCs. The performance of EDLCs, assembled with bucky gel electrodes, using impedance spectroscopy, cyclic voltammetry and charge-discharge analyses, are compared with those fabricated with pristine MWCNT-electrodes. An improvement in specific capacitance (from 19.6 to 51.3 F g(-1)) is noted when pristine MWCNTs are replaced by gelled MWCNT-binderless electrodes. Although the rate performance of the EDLCs with gelled MWCNT-electrodes is reduced, the pulse power of the device is sufficiently high (~10.5 kW kg(-1)). The gelled electrodes offer improvements in energy and power densities from 2.8 to 8.0 Wh kg(-1) and 2.0 to 4.7 kW kg(-1), respectively. Studies indicate that the gel formation of MWCNTs with ionic liquid is an excellent route to obtain high-performance EDLCs. PMID:24157648

Singh, Manoj K; Kumar, Yogesh; Hashmi, S A

2013-11-22

255

Three-dimensional hierarchical GeSe2 nanostructures for high performance flexible all-solid-state supercapacitors.  

PubMed

Highly flexible stacked and in-plane all-solid-state supercapacitors are fabricated on 3D hierarchical GeSe2 nanostructures with high performance, and, when configured as a self-powered photodetector nanosystem, can be used to power CdSe nanowire photodetectors. PMID:23180449

Wang, Xianfu; Liu, Bin; Wang, Qiufan; Song, Weifeng; Hou, Xiaojuan; Chen, Di; Cheng, Yi-bing; Shen, Guozhen

2013-03-13

256

Mechanical properties of high performance fibers vis-a-vis applications in flexible structural composites  

NASA Astrophysics Data System (ADS)

Some of the critical properties of high performance organic fibers and fiber assemblies have been addressed vis-a-vis their applications in flexible structural composites. These include: tensile properties; mechanical properties under complex modes of deformation; creep at high tensile loads; changes in physical properties due to thermo-mechanical/chemical treatments used in manufacturing of reinforced rubber goods. The axial elastic modulus of fibers and tautly twisted filament assemblies of high performance organic polymers have been measured along with their crystalline orientation distributions. Based on well established procedures in continuum mechanics of axially symmetric structures, a quantitative relationship has been derived to relate the axial elastic modulus to the second and fourth moment of average crystalline orientation distribution. The latter was determined by X-ray diffraction measurements with yarns. This model, valid for single-phase materials, has been found to provide an excellent fit of data from twisted yams of aromatic polyamide and highly ordered polyethylene fibers, with a wide range of overall crystalline orientation distributions. An important property of concern in engineering applications of polymeric filament assemblies of high performance organic fibers is creep. In this study, creep deformation data of gel-spun Ultra High Molecular Weight Polyethylne (UHMWPE) SpectraRTM 1000 yams have been fitted to a model obtained through an empirical mechanical analog of the viscoelastic process. The non-linear viscoelastic model composed of stress-dependent non-linear mechanical analogs qualitatively predicted the creep response to a series of step-loads applied on the UHMWPE yarns. To understand the mechanical properties of high performance organic fibers under combined bending and extension, a simple pin-test procedure has been employed to characterize fibers and twisted yarns. The results obtained from the test have been interpreted with regard to the mechanisms through which fibers can exhibit superior performance characteristics under such deformation conditions. An exploratory study of the changes in the mechanical properties of poly(p-phenylene terephthalamide) (PPTA) fibers due to the thermo-mechanical/chemical treatments used in commercial manufacturing of reinforced rubber goods has been conducted. The changes in tensile properties of PPTA yams have been inferred to be due to the process-induced changes in the overall crystalline orientation distribution.

Sharma, Varunesh

257

Pavement Marking Management System Database, User's Guide.  

National Technical Information Service (NTIS)

Pavement markings play a critical role in maintaining a safe and efficient driving environment for road users, especially during nighttime conditions. The Texas Department of Transportation (TxDOT) spends millions of dollars each year for installation and...

Y. Zhang

2011-01-01

258

Maintenance Methods for Continuously Reinforced Concrete Pavements.  

National Technical Information Service (NTIS)

In late 1974, test maintenance sections were constructed on a section of I-65 south of Indianapolis, Indiana. The road was stratified into 'similar' sections of pavement using deflection, cracking, and breakup as selection criteria. Various types of measu...

S. J. Virkler

1978-01-01

259

Long Term Monitoring of Moisture Under Pavements.  

National Technical Information Service (NTIS)

Monitoring of the environmental instrumentation installed under select pavement sections constructed by the Ohio Department of Transportation (ODOT) in 1995 on US 23 in Delaware County, Ohio was continued. The measurements made consisted of soil moisture,...

J. Howdyshell T. Butalia W. Wolfe

2010-01-01

260

Vibration Spectroscopy for Rigid Pavement Joint Assessment.  

National Technical Information Service (NTIS)

The study was conducted on the behavior of joints in concrete pavements, and on developing a non-destructive testing technique based on the frequency response of dynamically loaded joints. One of the objectives was to investigate the relationship between ...

L. Palmieri T. Krauthammer

1990-01-01

261

Evaluation of Concrete Pavement Patching Techniques.  

National Technical Information Service (NTIS)

The report presents the results of a study undertaken to improve in concrete pavement patching techniques. Activities included an evaluation of the suitability of the impact hammer and maturity calculations for determining when a patch is ready toreceive ...

M. M. Sprinkel K. K. McGhee

1989-01-01

262

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...

263

Pressure Relief Joints for Rigid Pavements.  

National Technical Information Service (NTIS)

The report was prepared to focus attention on damage occurring to some highway bridges as a result of pressure exerted by adjacent rigid pavement slabs. The report illustrates some of the conditions preceding serious bridge damage, and describes several t...

D. E. Gordinier W. P. Chamberlin

1969-01-01

264

Pilot Implementation of Concrete Pavement Thickness GPR.  

National Technical Information Service (NTIS)

Research Project 5-4414 'Pilot Implementation of Concrete Pavement Thickness GPR (CPT-GPR)' has been successfully completed. In this project, two CPT-GPR systems were manufactured, including GPR electronics, thickness and dielectric constant calculation a...

R. Liu J. Li X. Chen H. Xing

2004-01-01

265

Synergistic effects from graphene and carbon nanotubes enable flexible and robust electrodes for high-performance supercapacitors.  

PubMed

Flexible and lightweight energy storage systems have received tremendous interest recently due to their potential applications in wearable electronics, roll-up displays, and other devices. To manufacture such systems, flexible electrodes with desired mechanical and electrochemical properties are critical. Herein we present a novel method to fabricate conductive, highly flexible, and robust film supercapacitor electrodes based on graphene/MnO(2)/CNTs nanocomposites. The synergistic effects from graphene, CNTs, and MnO(2) deliver outstanding mechanical properties (tensile strength of 48 MPa) and superior electrochemical activity that were not achieved by any of these components alone. These flexible electrodes allow highly active material loading (71 wt % MnO(2)), areal density (8.80 mg/cm(2)), and high specific capacitance (372 F/g) with excellent rate capability for supercapacitors without the need of current collectors and binders. The film can also be wound around 0.5 mm diameter rods for fabricating full cells with high performance, showing significant potential in flexible energy storage devices. PMID:22823066

Cheng, Yingwen; Lu, Songtao; Zhang, Hongbo; Varanasi, Chakrapani V; Liu, Jie

2012-08-01

266

Development of Performance Properties of Ternary Mixtures and Concrete Pavement Mixture Design and Analysis (MDA): Effect of Paste Quality on Fresh and Hardened Properties of Ternary Mixtures.  

National Technical Information Service (NTIS)

The purpose of this study was to investigate the effect of cement paste quality on the concrete performance, particularly fresh properties, by changing the water-to-cementitious materials ratio (w/cm), type and dosage of supplementary cementitious materia...

G. Fick K. Wang P. Taylor P. Tikalsky X. Wan

2012-01-01

267

Pavement design with central plant hot-mix recycled asphalt mixes  

Microsoft Academic Search

Central plant hot mix recycling is one of the popular techniques adopted for recycling of asphalt pavement materials. Literature review reports varied levels of performances (laboratory as well as field) of recycled mix compared to the performances of corresponding virgin mixes. Thus, there is a need for conducting performance-related tests before finalizing any recycled mix design. The present paper discusses

K. Aravind; Animesh Das

2007-01-01

268

Influence of bending mode shape and trailing edge deflection on propulsive performance of flexible heaving fins using digital image correlation  

NASA Astrophysics Data System (ADS)

The propulsive performance of flexible flapping fins greatly depends on the stiffness of the fins along with the oscillating parameters. The bending mode shape and trailing edge deflection of the oscillating fins play a major role in the generation of thrust and efficiency. This paper examines the deformation pattern of heaving flexible foils and its dependency on propulsive performance. Experimental investigation has been carried out on fins of various lengths oscillating at their leading edge. A LaVision 2D/3D StrainMaster Digital Image Correlation (DIC) system was used to measure the deformation of the fins. It is observed that the propulsive performance can be maximized by operating at frequencies close to resonance. Trailing edge amplitude and deformation pattern together play an important role in achieving high propulsive performance even when the oscillation frequency is not close to resonant frequency.

Kancharala, Ashok K.; Dewillie, Kevin; Philen, Michael K.

2014-03-01

269

Reducing traffic noise with quieter pavements  

NASA Astrophysics Data System (ADS)

In recent years, interest has increased in the use of pavement type to reduce traffic noise. This has been driven by public concern over noise from freeways and state transportation agencies' interest in using pavement instead of sound walls to mitigate traffic noise. Beginnings of the recent interest go back to 1998 with the formation of the Institute for Safe, Quiet & Durable Highways at Purdue University and the initiation long-term research by the California Department of Transportation (Caltrans) on the effectiveness of quieter pavements. In 2002, the State of Arizona announced plans to overlay 115 miles of concrete freeway in the greater Phoenix area with a quieter asphalt rubber surface. This turned into the first Quiet Pavement Pilot Program in partnership between Federal Highway Administration (FHWA) and the Arizona Department of Transportation. Since that time, the FHWA in cooperation with the American Association of State Highway Transportation Agencies conducted a fact finding ``Scan'' tour in Europe to evaluate their quiet pavement technology and policy. This was followed by the first comparative tire/pavement noise testing in the US and Europe using the same procedures and test tires. The results, issues, and future directions surrounding these activities will be discussed.

Donavan, Paul

2005-09-01

270

Employment Flexibility and Firm Performance: Examining the Interaction Effects of Employment Mode, Environmental Dynamism, and Technological Intensity  

Microsoft Academic Search

Building on recent arguments advocating the benefits of different types of employment flexibility, we examine the relationships among the four types of employment (knowledge-based, job-based, contract, and alliances) and firm performance. The results indicate that a greater use of knowledge-based employment and contract work is positively associated with firm performance. The results also indicate that both knowledge-based employment and contract

David P. Lepak; Riki Takeuchi; Scott A. Snell

2003-01-01

271

PAVEMENT EVALUATION AND DEVELOPMENT OF SEASONAL AND TEMPERATURE ADJUSTMENT MODELS USING SEISMIC PAVEMENT ANALYZER (SPA)  

Microsoft Academic Search

Changes in material properties of pavement layers with temperature and seasonal climate variations significantly affect the pavement response. The AASHTO design guide requires that seasonal and temperature corrections be taken into consideration. Since the AASHTO adjustment models were developed based on data collected in Illinois, most of the states initiated studies that would take in consideration state specific conditions. New

Nenad Gucunski; Sameh Zaghloul; Rambod Hadidi; Ali Maher; Tony Chmiel

272

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.

Jinping, Li; Xiaojuan, Quan

2013-01-01

273

Comparative Field Measurements of Tire Pavement Noise of Selected Texas Pavements  

Microsoft Academic Search

The effects of traffic noise are a serious concern in the United States and the world. One significant component of traffic noise is tire\\/pavement interaction. Protecting individual receivers by reducing pavement noise at the source rather than by using traffic noise barriers may result in substantial cost reductions and improved community acceptance of highway projects. This research conducted field testing

Michael T. McNerney; B. J. Landsberger; Tracy Turen; Albert Pandelides

1998-01-01

274

Graphene-patched CNT/MnO2 nanocomposite papers for the electrode of high-performance flexible asymmetric supercapacitors.  

PubMed

MnO2 has been widely studied as the pseudo-capactive electrode material of high-performance supercapacitors for its large operating voltage, low cost, and environmental friendliness. However, it suffers from low conductivity and being hardly handle as the electrodes of supercapacitors especially with flexibility, which largely limit its electrochemical performance and application. Herein, we report a novel ternary composite paper composed of reduced graphene sheet (GR)-patched carbon nanotube (CNT)/MnO2, which has controllable structures and prominent electrochemical properties for a flexible electrode of the supercapacitor. The composite paper was prepared by electrochemical deposition of MnO2 on a flexible CNT paper and further adsorption of GR on its surface to enhance the surface conductivity of the electrode and prohibit MnO2 nanospheres from detaching with the electrode. The presence of GR was found remarkably effective in enhancing the initial electrochemical capacitance of the composite paper from 280 F/g to 486.6 F/g. Furthermore, it ensures the stability of the capacitance after a long period of charge/discharge cycles. A flexible CNT/polyaniline/CNT/MnO2/GR asymmetric supercapacitor was assembled with this composite paper as an electrode and aqueous electrolyte gel as the separator. Its operating voltage reached 1.6 V, with an energy density at 24.8 Wh/kg. Such a composite structure derived from a multiscale assembly can offer not only a robust scaffold loading MnO2 nanospheres but also a conductive network for efficient ionic and electronic transport; thus, it is potentially promising as a novel electrode architecture for high-performance flexible energy storage devices. PMID:23488813

Jin, Yu; Chen, Hongyuan; Chen, Minghai; Liu, Ning; Li, Qingwen

2013-04-24

275

Proceedings of the National Seminar on Asphalt Pavement Recycling.  

National Technical Information Service (NTIS)

The 19 papers in this report deal with the following areas: economics of recycling; seminar on asphalt pavement recycling overview of project selection; cost and energy considerations in project selection for recycling asphalt pavements; specifications re...

S. P. LaHue F. N. Finn W. J. Halstead R. C. Ingberg D. R. Gallagher

1980-01-01

276

Geotechnical Aspects of Pavements: Reference Manual/Participant Workbook.  

National Technical Information Service (NTIS)

This is the Reference Manual and Participants Workbook for the FHWA NHI's Course No. 132040--Geotechnical Aspects of Pavements. The manual covers the latest methods and procedures to address the geotechnical issues in pavement design, construction and per...

B. R. Christopher C. Schwartz R. Boudreau

2006-01-01

277

Density Measurement Verification for Hot Mix Asphalt Concrete Pavement Construction.  

National Technical Information Service (NTIS)

Oregon Department of Transportation (ODOT) requires a minimum density for the construction of dense-graded hot mix asphalt concrete (HMAC) pavements to ensure the likelihood that the pavement will not experience distresses that reduce the expected service...

S. Darra T. V. Scholz

2010-01-01

278

Use of Precast Slabs for Pavement Rehabilitation on I-66.  

National Technical Information Service (NTIS)

Highway agencies continuously strive to expedite pavement construction and repairs and to evaluate materials and methods to provide long-lasting pavements. As part of this effort, agencies have used precast concrete slabs for more than 10 years with succe...

C. Ozyildirim M. S. Hossain

2012-01-01

279

Recycling of Portland Cement Concrete Pavement, Johnson County.  

National Technical Information Service (NTIS)

In recent years there has been increasing interest in recycling construction materials. Surface courses of bituminous pavements are currently being actively recycled all over Kansas. The recycling of portland cement concrete pavements (PCCP) can help alle...

J. B. Wojakowski G. A. Fager M. A. Catron

1995-01-01

280

Effects of Pavement Type on Traffic Noise levels.  

National Technical Information Service (NTIS)

Tire/road levels for Ohio Department of Transportation (ODOT) pavement types were investigated to provide an additional criterion for pavement selection in noise senstivie areas. Tire/road noise measurments were conducted in accordance with the Internatio...

L. A. Herman M. J. Ambroziak

1999-01-01

281

Porous Pavement. Phase I. Design and Operational Criteria.  

National Technical Information Service (NTIS)

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 ap...

E. V. Diniz

1980-01-01

282

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 ...

283

Guide for Curing of Portland Cement Concrete Pavements, Volume 1.  

National Technical Information Service (NTIS)

This document provides guidance on details of concrete curing practice as they pertain to construction of portland cement concrete pavements. The guide is organized around the major events in curing pavements: curing immediately after placement (initial c...

2005-01-01

284

Assessing Green Infrastructure Performance Using Remote Hydologic Monitoring Measures  

EPA Science Inventory

Two locations in Cincinnati were instrumented with level sensing technologies to measure stormwater flow in porous pavement and bioretention areas. Results indicate good performance of porous pavement and a cost effective application of technology to measure those flows. Result...

285

Construction and testing of crumb rubber modified hot mix asphalt pavement. Interim report  

Microsoft Academic Search

This study was structured towards addressing that portion of ISTEA which directs the individual states to conduct studies on the recyclability of crumb rubber modified hot mix asphalt (CRMHMA), and the technical performance of CRMHMA pavement by monitoring the construction and evaluating the performance of highway test sections in which CRMHA is removed by cold milling and recycled into new

G. E. Albritton; G. R. Gatlin

1996-01-01

286

Thermoelectric Generators using Solar Thermal Energy in Heated Road Pavement  

Microsoft Academic Search

The temperature of road pavement rises up to 70degC in summer due to the effect of the solar radiation. The authors have developed a pavement-cooling system using thermoelectric generator. Heat in the pavement is collected as heated water in a heat collection tube installed in the pavement. River water near the road is used as a coolant. Electric power is

M. Hasebe; Y. Kamikawa; S. Meiarashi

2006-01-01

287

ANALYSIS OF PERFORMANCE OF PULSATING FLEXIBLE MAGNETIC ABRASIVE BRUSH (P-FMAB)  

Microsoft Academic Search

Direct current magnetic abrasive finishing process provides hardly any stirring effect on static flexible magnetic abrasive brush (S-FMAB). Continuous use of S-FMAB and absence of stirring leads to dullness of abrasive cutting edges resulting in low finishing rate. To overcome this weakness of the process, the FMAB has been made pulsating using pulse direct current (DC) power supply. Empirical models

V. K. Jain; D. K. Singh; V. Raghuram

2008-01-01

288

High performance TFT circuits foon-board display driving on flexible stainless steel foils  

Microsoft Academic Search

Displays are one of the preferred flexible electronic applications because of the mechanical and space saving advantages a conformal or foldable display would have (robust, lightweight). These systems would include in the same substrate all or many of the components needed to drive a flat panel OLED display. This study will report results on digital, analog and mixed signal poly-silicon

Matias Troccoli; Abbas Jamshidi; Ta-Ko Chuang; Miltiadis K. Hatalis

2005-01-01

289

Design of green engineered cementitious composites for pavement overlay applications  

Microsoft Academic Search

The construction, repair and rehabilitation of concrete pavements relies on the production and flow of large quantities of concrete and its constituents. Within the US, nearly 43 megatons of cement are used annually for the construction, repair and rehabilitation of concrete pavements, accounting for over 39 megatons of CO2 emissions. To reduce environmental impact and improve the sustainability of pavement

M. D. Lepech; G. A. Keoleian; S. Qian; V. C. Li

290

Physically Meaningful Harmonization of Tire\\/Pavement Friction Measurement Devices  

Microsoft Academic Search

Accurate characterization and evaluation of tire\\/pavement friction is critical in assuring runway and highway safety. Historically, Pavement Friction Measurement Devices (PFMDs) employing different measuring mechanisms have been used to evaluate tire\\/pavement friction. They yield significantly disparate friction coefficients under the same contact conditions. Currently, an empirically developed data harmonization method based on a reference device (Dynamic Friction Tester (DFT)) is

Madhura Priyanga Nishshanke Rajapakshe

2011-01-01

291

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

292

Design of overlays based on pavement condition, roughness, and deflections  

NASA Astrophysics Data System (ADS)

The development and use of a pavement maintenance rating system and the development of two procedures for designing the thickness of overlays are summarized. It is demonstrated that objective rating systems can be used to prioritize pavements scheduled for resurfacing and that the procedures for overlay design based on the existing pavement structure and on traffic loadings are practical.

McGhee, K. H.

1982-01-01

293

Digital image processing as a tool for pavement distress evaluation  

Microsoft Academic Search

The information obtained through accurate condition assessment of pavement surface distress data is needed as an essential input to any decision making process concerning pavement management policy. At the same time technological advances in automated inspection systems provide the opportunity to automate the collection and evaluation of the pavement surface condition. In this paper a method developed jointly by the

A. Georgopoulos; A. Loizos; A. Flouda

1995-01-01

294

Acoustic Aging of Asphalt Pavements: A Californian/Danish Comparison.  

National Technical Information Service (NTIS)

The level of noise generated by tire/pavement interaction of a pavement section changes over time. While the general consensus is that the noise level tends to increase as the pavement ages, more scientific investigation is necessary to better understand ...

E. Kohler H. Bendtsen Q. Lu

2010-01-01

295

Effects of selected pavement surface textures on tire noise  

Microsoft Academic Search

Modern methods of surface texturing to enhance concrete pavement skid-resistance by increasing texture depth resulted in increased tire-pavement noise, as compared to older finishing practices. Measurements of noise associated with textured concrete pavements representing the range of current and past practice in New York State are reported. A high correlation was found between the depth of textures created by brooming

R. J. Mitrey; D. E. Amsler; D. E. Suuronen

1975-01-01

296

Design and fabrication of high-performance polycrystalline silicon thin-film transistor circuits on flexible steel foils  

Microsoft Academic Search

This paper discusses in detail the design and fabrication process for the realization of high-performance polycrystalline silicon thin-film transistors and digital CMOS circuitry on thin flexible stainless steel foils. A comprehensive approach to substrate preparation is first presented. For transistor fabrication, distinct processing approaches are examined, such as solid-phase and excimer laser crystallization for the active semiconductor region, thermal growth

Themistokles Afentakis; Miltiadis Hatalis; Apostolos T. Voutsas; John Hartzell

2006-01-01

297

The behavior of a novel raw material-encapsulated FBG sensor for pavement monitoring  

NASA Astrophysics Data System (ADS)

Technology on pavement monitoring has been paid more and more attention by government, engineers and scholars. Conventional methods, such as artificial inspection and core sampling, have defect in low efficiency and limited coverage, and modern technologies, such as spectrum analysis and integral imaging, have poor resistance to external interference and high cost, which reveals that common approaches have fallen behind the development of road engineering. Therefore, a novel raw material-encapsulated FBG strain sensor is put forward, thinking over outstanding advantages of fiber Bragg grating and perfect incorporation between coating layers and host layers. Numerical analysis and experiments have been done to inspect behavior of the sensing system. Results indicate that it can well detect the actual performance of pavements, and the sensor presents a high-precision, real-time and long-term monitoring, owning function of road disaster warming, which promise it an extensive future in pavement monitoring.

Wang, Huaping; Liu, Wanqiu; Zhou, Zhi; Wang, Shuhong; Li, Yuan

2011-11-01

298

Mobile acoustic system for the detection of surface-breaking cracks in pavement  

NASA Astrophysics Data System (ADS)

Monitoring the structural condition of road and airport pavement is an extremely critical task to ensure the safety and efficiency of teh transportation. The topic is relevant to both civil and military transportation infrastructure. The presence of damage in pavement, including surface cracking, depressions, swells, and wear, is inevitable due to the sever environmental and service loads that these structures must be subject to. Existing NDE techniques aimed at assessing the structural condition of pavement include Falling Weight Deflectometer, Ground Penetrating Radar, and acoustic methods based on surface waves. This paper presents improvements to the traditional surface-wave method for the detection of surface-breaking cracks in pavement. The advances include 1) the modeling of the problem as dipsersive waves propagating in a multilayer system, 2) the inclusion of post-processing algorithms based on the Wavelet Transform to improve the sensitivity and accuracy of the inspection, and 3) the use of non-contact, air-coupled acoustic detectors to enhance the mobility of the inspection unit. The crack detection procedure consists of first generating a dispersive wave with an impulse hammer, and then measuring the changes in velocity, amplitude and/or frequency content as the wave travels across the flaw with the aid of the Continuous Wavelet Transform. Multilayer wave propagation modeling provides a better understanding of the experimental results by predicting how the various frequencies interact with cracks of different depths. The results of field tests will be presented for both rigid (concrete-based) and flexible (bitumen-based) pavement with surface cracks.

Marzani, Alessandro; Rizzo, Piervincenzo; Lanza di Scalea, Francesco; Benzoni, Gianmario

2004-07-01

299

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

300

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

301

Germanium nanoparticles encapsulated in flexible carbon nanofibers as self-supported electrodes for high performance lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Germanium is a promising high-capacity anode material for lithium ion batteries, but still suffers from poor cyclability due to its huge volume variation during the Li-Ge alloy/dealloy process. Here we rationally designed a flexible and self-supported electrode consisting of Ge nanoparticles encapsulated in carbon nanofibers (Ge-CNFs) by using a facile electrospinning technique as potential anodes for Li-ion batteries. The Ge-CNFs exhibit excellent electrochemical performance with a reversible specific capacity of ~1420 mA h g-1 after 100 cycles at 0.15 C with only 0.1% decay per cycle (the theoretical specific capacity of Ge is 1624 mA h g-1). When cycled at a high current of 1 C, they still deliver a reversible specific capacity of 829 mA h g-1 after 250 cycles. The strategy and design are simple, effective, and versatile. This type of flexible electrodes is a promising solution for the development of flexible lithium-ion batteries with high power and energy densities.Germanium is a promising high-capacity anode material for lithium ion batteries, but still suffers from poor cyclability due to its huge volume variation during the Li-Ge alloy/dealloy process. Here we rationally designed a flexible and self-supported electrode consisting of Ge nanoparticles encapsulated in carbon nanofibers (Ge-CNFs) by using a facile electrospinning technique as potential anodes for Li-ion batteries. The Ge-CNFs exhibit excellent electrochemical performance with a reversible specific capacity of ~1420 mA h g-1 after 100 cycles at 0.15 C with only 0.1% decay per cycle (the theoretical specific capacity of Ge is 1624 mA h g-1). When cycled at a high current of 1 C, they still deliver a reversible specific capacity of 829 mA h g-1 after 250 cycles. The strategy and design are simple, effective, and versatile. This type of flexible electrodes is a promising solution for the development of flexible lithium-ion batteries with high power and energy densities. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00140k

Li, Weihan; Yang, Zhenzhong; Cheng, Jianxiu; Zhong, Xiongwu; Gu, Lin; Yu, Yan

2014-04-01

302

High performance supercapacitors based on three-dimensional ultralight flexible manganese oxide nanosheets/carbon foam composites  

NASA Astrophysics Data System (ADS)

The syntheses and capacitance performances of ultralight and flexible MnO2/carbon foam (MnO2/CF) hybrids are systematically studied. Flexible carbon foam with a low mass density of 6.2 mg cm-3 and high porosity of 99.66% is simply obtained by carbonization of commercially available and low-cost melamine resin foam. With the high porous carbon foam as framework, ultrathin MnO2 nanosheets are grown through in situ redox reaction between KMnO4 and carbon foam. The three-dimensional (3D) MnO2/CF networks exhibit highly ordered hierarchical pore structure. Attributed to the good flexibility and ultralight weight, the MnO2/CF nanomaterials can be directly fabricated into supercapacitor electrodes without any binder and conductive agents. Moreover, the pseudocapacitance of the MnO2 nanosheets is enhanced by the fast ion diffusion in the three-dimensional porous architecture and by the conductive carbon foam skeleton as well as good contact of carbon/oxide interfaces. Supercapacitor based on the MnO2/CF composite with 3.4% weight percent of MnO2 shows a high specific capacitance of 1270.5 F g-1 (92.7% of the theoretical specific capacitance of MnO2) and high energy density of 86.2 Wh kg-1. The excellent capacitance performance of the present 3D ultralight and flexible nanomaterials make them promising candidates as electrode materials for supercapacitors.

He, Shuijian; Chen, Wei

2014-09-01

303

Hot Bituminous Pavement Gradation Acceptance Review of QC/QA Data 2000 to 2002.  

National Technical Information Service (NTIS)

This report analyzes the Quality Control/Quality Assurance (QC/QA) data for hot bituminous pavements using gradation acceptance awarded in the years 2000 to 2002. Analysis of the overall performance of the projects is accomplished by reviewing the Calcula...

E. Chavez

2004-01-01

304

Portland Cement Concrete Pavement Review of QC/QA Data 2000 Through 2009.  

National Technical Information Service (NTIS)

This report analyzes the Quality Control/Quality Assurance (QC/QA) data for Portland cement concrete pavement (PCCP) awarded in the years 2000 through 2009. Analysis of the overall performance of the projects is accomplished by reviewing the Calculated Pa...

J. Goldbaum V. DeLuccie

2011-01-01

305

Hot Bituminous Pavement Voids Acceptance Review of QC/QA Data 2000 through 2003.  

National Technical Information Service (NTIS)

This report analyzes the Quality Control/Quality Assurance (QC/QA) data for hot bituminous pavements using voids acceptance as the testing criteria awarded in the years 2000 through 2003. Analysis of the overall performance of the projects is accomplished...

E. Chavez

2005-01-01

306

Hot Bituminous Pavement Gradation Acceptance Review of QC/QA Data 2000 through 2003.  

National Technical Information Service (NTIS)

This report analyzes the Quality Control/Quality Assurance (QC/QA) data for hot bituminous pavements using gradation acceptance awarded in the years 2000 to 2003. Analysis of the overall performance of the projects is accomplished by reviewing the Calcula...

E. Chavez

2005-01-01

307

Permeable Pavement Research at NRMRL?s Urban Watershed Research Facility  

EPA Science Inventory

The results of a bench-scale study of a porous pavement parking lot. Flow rates and total suspended solids (TSS) removal are discussed for systems with a geotextile filter fabric liner in place and those without. The systems with a liner have ~20% better TSS removal performance a...

308

Analysis on shear stress in interlayer interface of concrete bride deck pavement  

Microsoft Academic Search

For studying the behavior of concrete bride deck pavement, the physiochemical property of interlayer interface was analyzed from microscopic view. Much initial pore and many initial cracks and low strength cement crystals were existed in the interlayer interface because of the cast time difference. A total of 32 samples were tested for studying the shear performance of pre- and post-casting

Hong Luo; Ling Luo; Liang Fan

2011-01-01

309

Comparing finite element and constitutive modelling techniques for predicting rutting of asphalt pavements  

Microsoft Academic Search

This paper focuses on a comprehensive evaluation of the effects of different finite element (FE) modelling techniques and material constitutive models on predicting rutting in asphalt pavements under repeated loading conditions. Different simplified 2D and more realistic 3D loading techniques are simulated and compared for predicting asphalt rutting. This study also evaluates and compares the rutting performance predictions using different

Rashid K. Abu Al-Rub; Masoud K. Darabi; Chien-Wei Huang; Eyad A. Masad; Dallas N. Little

2011-01-01

310

Comparing finite element and constitutive modelling techniques for predicting rutting of asphalt pavements  

Microsoft Academic Search

This paper focuses on a comprehensive evaluation of the effects of different finite element (FE) modelling techniques and material constitutive models on predicting rutting in asphalt pavements under repeated loading conditions. Different simplified 2D and more realistic 3D loading techniques are simulated and compared for predicting asphalt rutting. This study also evaluates and compares the rutting performance predictions using different

Rashid K. Abu Al-Rub; Masoud K. Darabi; Chien-Wei Huang; Eyad A. Masad; Dallas N. Little

2012-01-01

311

High-performance, fully transparent, and flexible zinc-doped indium oxide nanowire transistors  

Microsoft Academic Search

We report the fabrication of fully transparent and flexible nanowire transistors by combining a high-quality In2O3:Zn nanowire channel, a SiNx high-? dielectric, and conducting Sn-doped In2O3 electrodes on a polyethylene terephthalate substrate. The devices show excellent operating characteristics with high carrier mobilities up to 631 cm2 V?1 s?1, a drain-source current on\\/off modulation ratio ?1×106, a high on-state current ?1×10?5

W. F. Zhang; Z. B. He; G. D. Yuan; J. S. Jie; L. B. Luo; X. J. Zhang; Z. H. Chen; C. S. Lee; W. J. Zhang; S. T. Lee

2009-01-01

312

High-performance, fully transparent, and flexible zinc-doped indium oxide nanowire transistors  

Microsoft Academic Search

We report the fabrication of fully transparent and flexible nanowire transistors by combining a high-quality In2O3:Zn nanowire channel, a SiNx high-kappa dielectric, and conducting Sn-doped In2O3 electrodes on a polyethylene terephthalate substrate. The devices show excellent operating characteristics with high carrier mobilities up to 631 cm2 V-1 s-1, a drain-source current on\\/off modulation ratio ~1×106, a high on-state current ~1×10-5

W. F. Zhang; Z. B. He; G. D. Yuan; J. S. Jie; L. B. Luo; X. J. Zhang; Z. H. Chen; C. S. Lee; W. J. Zhang; S. T. Lee

2009-01-01

313

Flexible Flatfoot  

MedlinePLUS

... Conditions » Flexible Flatfoot Text Size Print Bookmark Flexible Flatfoot What Is Flatfoot? Flatfoot is often a complex disorder, with diverse ... develop as a result of a flatfoot. Flexible Flatfoot Flexible flatfoot is one of the most common ...

314

Temporary Pavement Marking Material Installation Procedure for Wet and Cold Pavement Conditions.  

National Technical Information Service (NTIS)

This report accumulates and consolidates with a single reference source the current state of technology with respect to the materials and application procedures used for temporary pavement markings. The report also contains a cost-comparison of the variou...

R. W. McNees J. S. Noel

1984-01-01

315

Fired-Clay Aggregates for Use in Flexible Bases.  

National Technical Information Service (NTIS)

A report is made on the phase concerning non-bloated, fired-clay synthetic aggregates for use in base course construction for flexible pavements. The report presents acceptance criteria for such aggregate based on a pressure slaking test developed by the ...

W. M. Moore

1969-01-01

316

Federal Aviation Administration Airport Pavement Management and Airport Pavement Roughness Evaluation  

Microsoft Academic Search

This paper provides the status of two ongoing nondestructive testing (NDT) programs by the FAA: (1) PAVEAIR a web-based Airport Pavement Management System and (2) research subjective responses of pilots to vibrations induced by airport pavement roughness using a Boeing simulator. By 2011, the FAA is scheduled to complete a three-year effort to create an internet-based computer program for airport

Albert LARKIN; Gordon F. HAYHOE

317

Germanium nanoparticles encapsulated in flexible carbon nanofibers as self-supported electrodes for high performance lithium-ion batteries.  

PubMed

Germanium is a promising high-capacity anode material for lithium ion batteries, but still suffers from poor cyclability due to its huge volume variation during the Li-Ge alloy/dealloy process. Here we rationally designed a flexible and self-supported electrode consisting of Ge nanoparticles encapsulated in carbon nanofibers (Ge-CNFs) by using a facile electrospinning technique as potential anodes for Li-ion batteries. The Ge-CNFs exhibit excellent electrochemical performance with a reversible specific capacity of ?1420 mA h g(-1) after 100 cycles at 0.15 C with only 0.1% decay per cycle (the theoretical specific capacity of Ge is 1624 mA h g(-1)). When cycled at a high current of 1 C, they still deliver a reversible specific capacity of 829 mA h g(-1) after 250 cycles. The strategy and design are simple, effective, and versatile. This type of flexible electrodes is a promising solution for the development of flexible lithium-ion batteries with high power and energy densities. PMID:24663690

Li, Weihan; Yang, Zhenzhong; Cheng, Jianxiu; Zhong, Xiongwu; Gu, Lin; Yu, Yan

2014-05-01

318

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.

2013-01-01

319

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

PubMed

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 >10(9) 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

320

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.

Kwak, Kiyeol; Cho, Kyoungah; Kim, Sangsig

2013-01-01

321

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.

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

2014-01-01

322

Desert pavement study at Amboy, California  

NASA Astrophysics Data System (ADS)

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.

1984-04-01

323

Concrete pavement analysis: the first eighty years  

Microsoft Academic Search

This paper traces the evolution of analytical methods for concrete pavements over the period from the publication of Westergaard's early work in the 1920s until today. It is demonstrated that this development was accomplished in parallel with the birth and coming of age of geotechnical engineering, and was likewise pioneered by a number of colorful and distinguished personalities. Westergaard's analysis

Anastasios M. Ioannides

2006-01-01

324

Airfield Pavement Evaluation - Usnaf El Centro, California.  

National Technical Information Service (NTIS)

The evaluation of the pavement at the U. S. Naval Air Facility, El Centro, California, is presented with the allowable gross load capacities of the runways, taxiways, and parking aprons for single, dual, single-tandem, and dual-tandem wheel assembly aircr...

R. J. Lowe W. H. Chamberlin

1966-01-01

325

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

326

Kansas Tire/Pavement Noise Study.  

National Technical Information Service (NTIS)

The purpose of this paper is to present the results of noise testing accomplished by the National Center for Asphalt Technology using a close-proximity noise trailer. The paper discusses the nature of tire/pavement noise and the results of testing selecte...

B. Waller D. I. Hanson R. S. James

2005-01-01

327

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

328

Laser scribing of high-performance and flexible graphene-based electrochemical capacitors.  

PubMed

Although electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. We used a standard LightScribe DVD optical drive to do the direct laser reduction of graphite oxide films to graphene. The produced films are mechanically robust, show high electrical conductivity (1738 siemens per meter) and specific surface area (1520 square meters per gram), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy density values in different electrolytes while maintaining the high power density and excellent cycle stability of ECs. Moreover, these ECs maintain excellent electrochemical attributes under high mechanical stress and thus hold promise for high-power, flexible electronics. PMID:22422977

El-Kady, Maher F; Strong, Veronica; Dubin, Sergey; Kaner, Richard B

2012-03-16

329

Improving electrochemical performance of flexible thin film electrodes with micropillar array structures  

NASA Astrophysics Data System (ADS)

For reliable function, bioelectrodes require a stable, low-impedance contact with the target tissue. In biosignal monitoring applications, in which low ion current densities are recorded, it is important to minimize electrode contact impedances. Recently, several flexible electrode concepts have been introduced for single-patient use. These electrodes conform well on the patient skin enabling an artifact-free, low-noise recording. In this study, polydimethylsiloxane (PDMS) elastomer was used as an electrode substrate material. One half of the substrates were surface-patterned with micropillars produced by using micro-working robot-made mold inserts and a replica molding technique. The substrates were subsequently coated with thin films of titanium (Ti), copper (Cu), silver (Ag) or silver-silver chloride (Ag/AgCl). Electrical impedance spectroscopy studies revealed that the micropillar structure caused statistically significant reductions in impedance modulus and phase for each coating candidate. The relative effect was strongest for pure Ag, for which the values of the real part (Z?) and the imaginary part (Z?) decreased to less than one tenth of the original (smooth) values. However, Ag/AgCl, as expected, proved to be a superior electrode material. Coating with chloride drastically reduced the interfacial impedance compared to pure Ag. Further significant reduction was achieved by the micropillars, since the phase angle declined from 10-13° (for smooth samples, f < 50 Hz) to a value as low as 5°. Equivalent circuit modeling was used to obtain a better understanding of phenomena occurring at various electrode-electrolyte interfaces. The knowledge obtained in this study will be exploited in the further development of flexible electrodes and miniaturized biointerfaces with improved electrochemical characteristics.

Myllymaa, Sami; Pirinen, Sami; Myllymaa, Katja; Suvanto, Mika; Pakkanen, Tapani A.; Pakkanen, Tuula T.; Lappalainen, Reijo

2012-12-01

330

Paper accepted for presentation at and publication in the Proceedings of the Third International Conference on APT in Madrid 2008 INNOVATIVE APPLICATIONS OF THE MLS10 FOR DEVELOPING PAVEMENT DESIGN SYSTEMS  

Microsoft Academic Search

This paper presents innovative applications of acce lerated pavement testing (APT) to advance pavement design in three case studies using MLS technology. Initially the MLS10 system was used to evaluate response and performance of ce ment stabilized coastal sand bases (CTB) in Mozambique. The object was development of guidelines for a mechanistic-empirical design method. Trafficking speed was varied with dual

Fred Hugo; Eben de Vos; Hilário Tayob; Louw Kannemeyer

331

State-of-the art guideline manual for design, quality control and construction of Sulfur-Extended-Asphalt (SEA) pavements  

Microsoft Academic Search

Sulfur-Extended-Asphalt (SEA) binders save asphalt, a potential energy source, by replacing some asphalt in conventional flexible pavement mixes with sulfur. These new binders appear to possess properties comparable to asphalt. The guideline manual discussed provides the highway community in both public and private organizations with the most definitive state-of-the-art guidelines extant for using these binders. Information on design, construction, quality

W. C. McBee; T. A. Sullivan; J. O. Izatt

1980-01-01

332

Pavement Recycling Guidelines for State and Local Governments. Participant's Reference Book.  

National Technical Information Service (NTIS)

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...

P. S. Kandhal R. B. Mallick

1997-01-01

333

Pavements Recycling Guidelines for State and Local Governments (on CD-ROM).  

National Technical Information Service (NTIS)

This participant's reference book was developed to support a 2-day workshop on pavement recycling guidelines for state and local governments. Recycling or reuse of existing asphalt pavement materials to produce new pavement materials has the following adv...

1998-01-01

334

76 FR 67018 - Notice to Manufacturers of Airport In-Pavement Stationary Runway Weather Information Systems  

Federal Register 2010, 2011, 2012, 2013

...Airport In-Pavement Stationary Runway Weather Information Systems AGENCY: Federal Aviation...Manufacturers of In-Pavement Stationary Runway Weather Information Systems...Passive In- Pavement Stationary Runway Weather Information Systems that meet the...

2011-10-28

335

23 CFR 970.208 - Federal lands pavement management system (PMS).  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Federal lands pavement management system (PMS). 970.208...Systems § 970.208 Federal lands pavement management system (PMS). In addition... (i) An inventory of the physical pavement features including the number of...

2009-04-01

336

23 CFR 970.208 - Federal lands pavement management system (PMS).  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Federal lands pavement management system (PMS). 970.208...Systems § 970.208 Federal lands pavement management system (PMS). In addition... (i) An inventory of the physical pavement features including the number of...

2010-04-01

337

Improved Drainage and Frost Action Criteria for New Jersey Pavement Design. Phase II. Data Analysis.  

National Technical Information Service (NTIS)

The feasibility of including open-graded drainage layers in their highway pavements was studied. Before constructing actual pavements with open-graded drainage layers, frost penetration depths and moisture content profiles beneath several pavements in New...

R. L. Berg

1979-01-01

338

Solution chemistry of self-assembled graphene nanohybrids for high-performance flexible biosensors.  

PubMed

We report the preparation of free-standing flexible conductive reduced graphene oxide/Nafion (RGON) hybrid films by a solution chemistry that utilizes self-assembly and directional convective-assembly. The hydrophobic backbone of Nafion provided well-defined integrated structures, on micro- and macroscales, for the construction of hybrid materials through self-assembly, while the hydrophilic sulfonate groups enabled highly stable dispersibility ( approximately 0.5 mg/mL) and long-term stability (2 months) for graphene. The geometrically interlocked morphology of RGON produced a high degree of mechanical integrity in the hybrid films, while the interpenetrating network constructed favorable conduction pathways for charge transport. Importantly, the synergistic electrochemical characteristics of RGON were attributed to high conductivity (1176 S/m), facilitated electron transfer (ET), and low interfacial resistance. Consequently, RGON films obtained the excellent figure of merit as electrochemical biosensing platforms for organophosphate (OP) detection, that is, a sensitivity of 10.7 nA/microM, detection limit of 1.37 x 10(-7) M, and response time of <3 s. In addition, the reliability of RGON biosensors was confirmed by a fatigue test of 100 bending cycles. The strategy described here provides insight into the fabrication of graphene and hybrid nanomaterials from a material perspective, as well as the design of biosensor platforms for practical device applications. PMID:20377244

Choi, Bong Gill; Park, Hoseok; Park, Tae Jung; Yang, Min Ho; Kim, Joon Sung; Jang, Sung-Yeon; Heo, Nam Su; Lee, Sang Yup; Kong, Jing; Hong, Won Hi

2010-05-25

339

Statistical analysis of acoustic measurements for assessing pavement surface condition  

NASA Astrophysics Data System (ADS)

This work presents a method for assessing pavement surface condition using measurements from a microphone mounted underneath a moving vehicle. Such measurements will include tire-generated sound, which carries much information about the road condition, as well as noise generated by the wind and vehicle. The proposed method uses Principal Component Analysis (PCA) to extract the tire-generated sound from the noisy measurements. The analysis begins with acoustic pressure measurements made over constant and known road conditions. Fourier transforms are taken over various time windows and a PCA is performed over the resulting vectors, yielding to a set of principal component vectors for that road condition. Each road condition is characterized by a set of principal component vectors. These vector sets are used to analyze measurements from a road with unknown road conditions by finding the vector set that best represents the acoustic measurements from that road. Successful applications of this method are demonstrated by accurate estimations of the mean texture depth (MTD) of pavement directly from acoustic measurements.

Zhang, Yiying; Ma, Xin; McDaniel, J. Gregory; Wang, Ming L.

2012-03-01

340

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

341

Porous flame-retarded asphalt pavement for highway tunnel  

Microsoft Academic Search

A new way to improve the tunnel fire protection by using flame-retarded porous asphalt pavement containing ATH powders was\\u000a introduced. Based on the miniature burning test designed and conducted, the burning time and temperature of porous asphalt\\u000a (PA) and flame-retarded porous asphalt (FRPA) were studied comparing with cement concrete pavement, dense-graded HMA and SMA.\\u000a Results of burning test and pavement

Shuguang Hu; Shaolong Huang; Qingjun Ding

2008-01-01

342

Electrochromic performance of reactive plasma-sputtered NiO x thin films on flexible PET\\/ITO substrates for flexible electrochromic devices  

Microsoft Academic Search

Electrochromic properties of NiOx (nickel oxide) thin films sputtered on 40?\\/? flexible PET (polyethylene terephthalate)\\/ITO (indium tin oxide) substrates were investigated. Metallic Ni target, sputtered by radio frequency (r.f.) power with argon gases and reacted with oxygen gases at room temperature (23°C), was proven to provide significant electrochromic properties. Cyclic voltammetry switching measurements found that only low driving voltages from

Yung-Sen Lin; Po-Wen Chen; Di-Jiun Lin; Pei-Ying Chuang; Tsung-Hsien Tsai; Yui-Chuin Shiah; Yueh-Chung Yu

2010-01-01

343

Hybrid green permeable pave with hexagonal modular pavement systems  

NASA Astrophysics Data System (ADS)

Modular permeable pavements are alternatives to the traditional impervious asphalt and concrete pavements. Pervious pore spaces in the surface allow for water to infiltrate into the pavement during rainfall events. As of their ability to allow water to quickly infiltrate through the surface, modular permeable pavements allow for reductions in runoff quantity and peak runoff rates. Even in areas where the underlying soil is not ideal for modular permeable pavements, the installation of under drains has still been shown to reflect these reductions. Modular permeable pavements have been regarded as an effective tool in helping with stormwater control. It also affects the water quality of stormwater runoff. Places using modular permeable pavement has been shown to cause a significant decrease in several heavy metal concentrations as well as suspended solids. Removal rates are dependent upon the material used for the pavers and sub-base material, as well as the surface void space. Most heavy metals are captured in the top layers of the void space fill media. Permeable pavements are now considered an effective BMP for reducing stormwater runoff volume and peak flow. This study examines the extent to which such combined pavement systems are capable of handling load from the vehicles. Experimental investigation were undertaken to quantify the compressive characteristics of the modular. Results shows impressive results of achieving high safety factor for daily life vehicles.

Rashid, M. A.; Abustan, I.; Hamzah, M. O.

2013-06-01

344

In situ repair of high-performance, flexible nanocrystal electronics for large-area fabrication and operation in air.  

PubMed

Colloidal semiconductor nanocrystal (NC) thin films have been integrated in light-emitting diodes, solar cells, field-effect transistors (FETs), and flexible, electronic circuits. However, NC devices are typically fabricated and operated in an inert environment since the reactive surface and high surface-to-volume ratio of NC materials render them sensitive to oxygen, water, and many solvents. This sensitivity has limited device scaling and large-scale device integration achievable by conventional fabrication technologies, which generally require ambient air and wet-chemical processing. Here, we present a simple, effective route to reverse the detrimental effects of chemical and environmental exposure, by incorporating, in situ, a chemical agent, namely, indium metal, which is thermally triggered to diffuse and repair the damage. Taking advantage of the recovery process, CdSe NC FETs are processed in air, patterned using the solvents of lithography, and packaged by atomic layer deposition to form large-area and flexible high-performance NC devices that operate stably in air. PMID:23952742

Choi, Ji-Hyuk; Oh, Soong Ju; Lai, Yuming; Kim, David K; Zhao, Tianshuo; Fafarman, Aaron T; Diroll, Benjamin T; Murray, Christopher B; Kagan, Cherie R

2013-09-24

345

Fabrication of high-quality ZnTe nanowires toward high-performance rigid/flexible visible-light photodetectors.  

PubMed

ZnTe is an important p-type semiconductor with great applications as field-effect transistors and photodetectors. In this paper, individual ZnTe nanowires based field-effect transistors was fabricated, showing evident p-type conductivity with an effect mobility of 11.3 cm(2)/Vs. Single ZnTe nanowire based photodetectors on rigid silicon substrate exhibited high sensitivity and excellent stability to visible incident light with responstivity and quantum efficiency as high as 1.87 × 10(5) A/W and 4.36 × 10(7)% respectively and are stable in a wide temperature range (25-250 °C). The polarization-sensitivity of the ZnTe nanowires was studied for the first time. The results revealed a periodic oscillation with the continuous variation of polarization angles. Besides, flexible photodetectors were also fabricated with the features of excellent flexibility, stability and sensitivity to visible incident light. Our work would enable application opportunities in using ZnTe nanowires for ultrahigh-performance photodetectors in scientific, commercial and industrial applications. PMID:23546161

Liu, Zhe; Chen, Gui; Liang, Bo; Yu, Gang; Huang, Hongtao; Chen, Di; Shen, Guozhen

2013-03-25

346

Effectiveness of transverse grooves in rigid pavement  

NASA Astrophysics Data System (ADS)

Transverse grooves were installed at 11 intersection approaches on worn rigid pavement to reduce a high rate of wet road accidents. In most cases, accident reductions were experienced only at intersections with multiple negative operational characteristics, including higher approach speeds, limited sight distances, and frequent vehicle stopping for turns or stop signs. Intersections with no more than one negative characteristic generally did not benefit from grooving.

Gurney, G. F.; Bryden, J. E.

1982-10-01

347

Multimodal approach to seismic pavement testing  

USGS Publications Warehouse

A multimodal approach to nondestructive seismic pavement testing is described. The presented approach is based on multichannel analysis of all types of seismic waves propagating along the surface of the pavement. The multichannel data acquisition method is replaced by multichannel simulation with one receiver. This method uses only one accelerometer-receiver and a light hammer-source, to generate a synthetic receiver array. This data acquisition technique is made possible through careful triggering of the source and results in such simplification of the technique that it is made generally available. Multiple dispersion curves are automatically and objectively extracted using the multichannel analysis of surface waves processing scheme, which is described. Resulting dispersion curves in the high frequency range match with theoretical Lamb waves in a free plate. At lower frequencies there are several branches of dispersion curves corresponding to the lower layers of different stiffness in the pavement system. The observed behavior of multimodal dispersion curves is in agreement with theory, which has been validated through both numerical modeling and the transfer matrix method, by solving for complex wave numbers. ?? ASCE / JUNE 2004.

Ryden, N.; Park, C. B.; Ulriksen, P.; Miller, R. D.

2004-01-01

348

Assessing the improved performance of freestanding, flexible graphene and carbon nanotube hybrid foams for lithium ion battery anodes.  

PubMed

We demonstrate the fabrication of three-dimensional freestanding foams of hybrid graphene-single-walled carbon nanotube nanomanufactured materials with reversible capacities of 2640 mA h g(-1) at 0.186 A g(-1) and 236 mA h g(-1) at 27.9 A g(-1). The Li storage behavior of this material is compared against other nanostructures in similar flexible foam platforms including graphene, ultra-thin graphite, and single-walled carbon nanotubes (SWNTs), and we elucidate the improved hybrid material performance due to the decoupling of lithium storage reaction energetics dictated by the SWNTs from the total storage capacity of the hybrid material. This work demonstrates a route to develop mechanically robust all-carbon electrodes with the potential for reversible Li-ion storage capacity approaching silicon, power capability of the best supercapacitors, and based on a material simultaneously usable as a charge collector and anode. PMID:24647668

Cohn, Adam P; Oakes, Landon; Carter, Rachel; Chatterjee, Shahana; Westover, Andrew S; Share, Keith; Pint, Cary L

2014-05-01

349

Enhanced performance of flexible nanocrystalline silicon thin-film solar cells using seed layers with high hydrogen dilution.  

PubMed

Flexible hydrogenated nanocrystalline (nc-Si:H) thin-film solar cells were prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD), and the effect of highly crystalline intrinsic Si seed layers at the initial growth stage of i nc-Si:H absorbers on their structural and electrical properties and on the performance of solar cells was investigated. The crystallization of i nc-Si:H absorbers was significantly enforced by the introduction of highly crystalline seed layers, resulting in the reduction of defect-dense a-Si:H grain boundary and incubation layer thickness. The open circuit voltage of the nc-Si:H solar cells with the seed layers was improved by the decrease of charged defect density in the defect-rich amorphous region. PMID:24266159

Lee, Ji-Eun; Kim, Donghwan; Yoon, Kyung Hoon; Cho, Jun-Sik

2013-12-01

350

Exploiting the Routing Flexibility for Energy\\/Performance Aware Mapping of Regular NoC Architectures  

Microsoft Academic Search

In this paper, we present an algorithm which automatically maps the IPs onto a generic regular Network on Chip (NoC) architecture and constructs a deadlock-free deterministic routing function such that the total communication energy is minimized. At the same time, the performance of the resulting communication system is guaranteed to satisfy the specified constraints through bandwidth reservation. As the main

Jingcao Hu; Radu Marculescu

2003-01-01

351

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

352

Working memory performance and cognitive flexibility after dexamethasone or hydrocortisone administration in healthy volunteers  

Microsoft Academic Search

Objective  Several studies have shown that glucocorticoids can impair declarative memory retrieval and working memory (WM) performance.\\u000a The aim of the present study was to investigate the impact of a high dose of hydrocortisone on WM, as well as to examine the\\u000a effects of cortisol suppression via treatment with a high dose of dexamethasone (DEX). We hypothesized that hydrocortisone\\u000a treatment results

Katja Wingenfeld; Susanne Wolf; Jürgen-Christian Krieg; Stefan Lautenbacher

353

Influence of heating on performances of flexible hollow waveguides for the mid-infrared  

NASA Astrophysics Data System (ADS)

Two types (plastic and fused silica) of waveguides suitable for transmitting 0022-3727/29/3/013/img1 and Er-YAG laser radiation were prepared and characterized. The temperature of several points on the external surface of the waveguides was measured. Optical parameters (transmission, focusing, misalignment) of the two types of waveguides were measured and compared. The importance of heating (due to losses) on the long time delivery performance is also shown.

Dror, J.; Inberg, A.; Dahan, R.; Elboim, A.; Croitoru, N.

1996-03-01

354

High performance printed N and P-type OTFTs enabling digital and analog complementary circuits on flexible plastic substrate  

NASA Astrophysics Data System (ADS)

This paper presents a printed organic complementary technology on flexible plastic substrate with high performance N and P-type Organic Thin Film Transistors (OTFTs), based on small-molecule organic semiconductors in solution. Challenges related to the integration of both OTFT types in a common complementary flow are addressed, showing the importance of surface treatments. Stability on single devices and on an elementary complementary digital circuit (ring oscillator) is studied, demonstrating that a robust and reliable flow with high electrical performances can be established for printed organic devices. These devices are used to manufacture several analog and digital building blocks. The design is carried out using a model specifically developed for this technology, and taking into account the parametric variability. High-frequency measurements of printed envelope detectors show improved speed performance, resulting from the high mobility of the OTFTs. In addition, a compact dynamic flip-flop and a low-offset comparator are demonstrated, thanks to availability of both n-type and p-type OTFTs in the technology. Measurement results are in good agreement with the simulations. The circuits presented establish a complete library of building blocks for the realization of a printed RFID tag.

Jacob, S.; Abdinia, S.; Benwadih, M.; Bablet, J.; Chartier, I.; Gwoziecki, R.; Cantatore, E.; van Roermund, A. H. M.; Maddiona, L.; Tramontana, F.; Maiellaro, G.; Mariucci, L.; Rapisarda, M.; Palmisano, G.; Coppard, R.

2013-06-01

355

Effect of induced deformation on NDT pavement evaluation  

NASA Astrophysics Data System (ADS)

Three nondestructive testing techniques were used in this study to evaluate pavement layer properties. These techniques included deflection and seismic methods. In the deflection methods, measurable surface deformations were induced using falling weight deflectometer and Dynaflect tests. These two tests utilized different schemes of dynamic loading applications to produce deflection basins from which the pavement layer properties were back calculated. Pavement properties from seismic methods were obtained from the analysis of surface waves due to transient load applications. In this study the seismic pavement analyzer (SPA) was used to determine pavement moduli values. Although the same assumptions for linear elastic behavior of pavement properties are usually assumed in all the three methods, obtained moduli values from these techniques did not conform to each other. Commonly, pavement deflection from SPA is not considered when analyzing layer properties. To narrow the gap between the obtained results, however, time-history records and frequency response functions were used to determine surface deflections from the three methods. Deflection measurements correlated with the obtained moduli values. Using these correlations, moduli values at any pavement deflection levels could be evaluated, especially at levels produced by traffic loads.

Tawfiq, Kamal S.; Sobanjo, John O.; Ruiz, R.

1999-02-01

356

Field investigation of clogging in a permeable pavement system  

Microsoft Academic Search

Permeable pavements are commonly used around commercial and industrial buildings to reduce the environmental impact. Results are presented from a forensic investigation of a permeable interlocking concrete paving (PICP) system that has been in service for over eight years. The aims were to quantify the sediment accumulation processes that occurred in the different pavement layers and to improve understanding of

Terry Lucke; Simon Beecham

2011-01-01

357

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.

358

Analytical Study of Probable Peak Vehicle Load on Rigid Pavement  

Microsoft Academic Search

Because of the lack of formulas for evaluating the peak value of dynamic vehicle load on rigid pavement, the need to derive a simple closed-form solution to predict the peak load for pavement design is apparent. Presented herein is a theoretical solution for evaluating the probable peak vehicle load on rigid pave- ment due to the passage of a vehicle

Jeng-Hsiang Lin; Cheng-Chiang Weng

2001-01-01

359

Control of Grasses and Weeds Growing in Asphalt Pavements  

Microsoft Academic Search

Herbicides offer the engineer a means for controlling vegetation involving asphalt surfaces. The plants may arise from seeds or plant parts in the base material, by encroachment of plants from outside the pavement, or from seeds that become lodged in cracks or seams in the pavement.Bermuda grass (Cynodon dactylon) and many associated plants can be controlled with either pre-surface or

Wayne G. McCully; William J. Bowmer; Allen F. Wiese

1970-01-01

360

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...

361

Climatic-Materials-Structural Pavement Analysis Program. User's Manual.  

National Technical Information Service (NTIS)

The publication is the User's Manual for the Climatic-Materials-Structural Pavement Analysis Program (CMS program) which is described in detail in the report entitled 'Volume 3. Environmental Effects on Pavements - Theory Manual, FHWA/RD-84-115.' The CMS ...

W. A. Herlache A. J. Patel B. J. Dempsey

1985-01-01

362

Hot-Recycling of Tar-Containing Asphalt Pavements  

Microsoft Academic Search

Hot recycling in pavement construction leads to the emission of hazardous compounds when tar-containing recycled asphalt pavement (RAP) is used. This is due to the relatively high content of substances such as phenols and polycyclic aromatic hydrocarbons (PAH) in tar. The latter are of special interest, because some PAHs have carcinogenic and\\/or mutagenic properties. High tar content in combination with

Martin Hugener; Lukas Emmenegger; Peter Mattrel

2010-01-01

363

Microwave methods enable energy savings in restoration of highway pavements  

Microsoft Academic Search

Hot in place recycling of asphalt pavement by a method which utilizes microwave energy in combination with hot engine exhaust gases has been demonstrated to be technically and economically feasible. The process saves both energy and materials compared with conventional hot-mix recycling methods involving removal of old paving and reprocessing at hot-mix plants. Applications for microwave pavement heating include repair

M. R. Jeppson; F. J. Smith

1983-01-01

364

Effect of redox label tether length and flexibility on sensor performance of displacement-based electrochemical DNA sensors.  

PubMed

This article summarizes the sensor performance of four electrochemical DNA sensors that exploit the recently developed displacement-replacement sensing motif. In the absence of the target, the capture probe is partially hybridized to the signaling probe at the distal end, positioning the redox label, methylene blue (MB), away from the electrode. In the presence of the target, the MB-modified signaling probe is released; one type of probe is capable of assuming a stem-loop probe (SLP) conformation, whereas the other type adopts a linear probe (LP) conformation. Independent of the sensor architecture, all four sensors showed "signal-on" sensor behavior. Unlike the previous report, here we focused on elucidating the effect of the redox label tether length and flexibility on sensor sensitivity, specificity, selectivity, and reusability. For both SLP and LP sensors, the limit of detection was 10 pM for sensors fabricated using a signaling probe with three extra thymine (T3) bases linked to the MB label. A limit of detection of 100 pM was determined for sensors fabricated using a signaling probe with five extra thymine (T5) bases. The linear dynamic range was between 10 pM and 100 nM for the T3 sensors, and between 100 pM and 100 nM for the T5 sensors. When compared to the LP sensors, the SLP sensors showed higher signal enhancement in the presence of the full-complement target. More importantly, the SLP-T5 sensor was found to be highly specific; it is capable of discriminating between the full complement and single-base mismatch targets even when employed in undiluted blood serum. Overall, these results highlight the advantages of using oligo-T(s) as a tunable linker to control flexibility of the tethered redox label, so as to achieve the desired sensor response. PMID:24491779

Yu, Zhi-gang; Zaitouna, Anita J; Lai, Rebecca Y

2014-02-17

365

Use of coal ash in highway pavements: Kansas Demonstration Project  

SciTech Connect

This report documents the use of cementitious type C coal ash in three Kansas roadbase stabilization projects that included an extensive laboratory study, as well as subsequent monitoring of the roads for structural stability and evaluation of leaching potential into the underlying soils. The projects were intended to demonstrate that the process proposed could recycle existing roadway materials in place. The study showed that conventional recycling equipment can achieve satisfactory pulverization, mixing, and compaction. Further, after more than two years of service, the stabilized sections have exhibited no signs of deterioration due to traffic, weather, or frost. The only problems observed to data release to adhesion of the wearing surface to the fly-ash-stabilized base sections. Proper selection of tack-coat materials should minimize this problem. The results of the laboratory study correlated well with the observed pavement performance.

Ferguson, G.; Zey, J.

1992-01-01

366

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

367

Study on pavement technologies to mitigate the heat island effect and their effectiveness  

Microsoft Academic Search

Recently, the heat island effect in large cities has become a social issue in Japan. Pavements are thought to be one of the main causes of the heat island effect as they cover wide area of cities. Therefore, new pavements, such as water retention pavements or heat shield pavements, have been developed and used as countermeasures by the central and

K. Kubo; H. KIDO

368

Effects of a short proprioceptive neuromuscular facilitation stretching bout on quadriceps neuromuscular function, flexibility, and vertical jump performance.  

PubMed

The inclusion of relatively long bouts of stretching (repeated static stretches of ?30 seconds) in the warm-up is usually associated with a drop in muscle performance. The purpose of this study was to assess the effect of a novel self-administered proprioceptive neuromuscular facilitation (PNF) paradigm with short periods of stretching and contraction on quadriceps neuromuscular function, vertical jump performance, and articular range of motion (ROM). Twelve healthy men (age: 27.7 ± 7.3 years, height: 178.4 ± 10.4 cm, weight: 73.8 ± 16.9 kg) volunteered to participate in a PNF session and a control session separated by 2-7 days. The PNF stretching lasted 2 minutes and consisted of 4 sets of 5-second isometric hamstring contraction immediately followed by 5 seconds of passive static stretch of the quadriceps immediately followed by 5 seconds isometric quadriceps contraction for each leg. For the control session, the participants were asked to walk at a comfortable speed for 2 minutes. Active ROM of knee flexion, vertical jump performance, and quadriceps neuromuscular function were tested before, immediately after, and 15 minutes after the intervention. The PNF stretching procedure did not affect ROM, squat jump, and countermovement jump performances. Accordingly, we did not observe any change in maximal voluntary contraction force, voluntary activation level, M-wave and twitch contractile properties that could be attributed to PNF stretching. The present self-administered PNF stretching of the quadriceps with short (5-second) stretches is not recommended before sports where flexibility is mandatory for performance. PMID:22505131

Place, Nicolas; Blum, Yannick; Armand, Stéphane; Maffiuletti, Nicola A; Behm, David G

2013-02-01

369

New Structural Systems for Zero-Maintenance Pavements. Volume 3. Anchored Pavement System Designed for Edens Expressway.  

National Technical Information Service (NTIS)

This report provides an analysis example of an actual pavement and the cost estimate using the anchored system. The actual pavement is the Edens Expressway in Chicago. The report provides the response of the Edens Expressway subjected to mechanical and en...

S. G. Militsopoulos S. K. Saxena

1980-01-01

370

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

371

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

372

Assessing the improved performance of freestanding, flexible graphene and carbon nanotube hybrid foams for lithium ion battery anodes  

NASA Astrophysics Data System (ADS)

We demonstrate the fabrication of three-dimensional freestanding foams of hybrid graphene-single-walled carbon nanotube nanomanufactured materials with reversible capacities of 2640 mA h g-1 at 0.186 A g-1 and 236 mA h g-1 at 27.9 A g-1. The Li storage behavior of this material is compared against other nanostructures in similar flexible foam platforms including graphene, ultra-thin graphite, and single-walled carbon nanotubes (SWNTs), and we elucidate the improved hybrid material performance due to the decoupling of lithium storage reaction energetics dictated by the SWNTs from the total storage capacity of the hybrid material. This work demonstrates a route to develop mechanically robust all-carbon electrodes with the potential for reversible Li-ion storage capacity approaching silicon, power capability of the best supercapacitors, and based on a material simultaneously usable as a charge collector and anode.We demonstrate the fabrication of three-dimensional freestanding foams of hybrid graphene-single-walled carbon nanotube nanomanufactured materials with reversible capacities of 2640 mA h g-1 at 0.186 A g-1 and 236 mA h g-1 at 27.9 A g-1. The Li storage behavior of this material is compared against other nanostructures in similar flexible foam platforms including graphene, ultra-thin graphite, and single-walled carbon nanotubes (SWNTs), and we elucidate the improved hybrid material performance due to the decoupling of lithium storage reaction energetics dictated by the SWNTs from the total storage capacity of the hybrid material. This work demonstrates a route to develop mechanically robust all-carbon electrodes with the potential for reversible Li-ion storage capacity approaching silicon, power capability of the best supercapacitors, and based on a material simultaneously usable as a charge collector and anode. Electronic supplementary information (ESI) available: ESI is available that includes (i) SEM and photographs of ultra-thin graphite foams, (ii) Raman spectra from SWNT and ultrathin graphite foams, (iii) CV measurements at higher scan rates, (iv) comparison of discharge characteristics of first, second, and 300th discharge, (v) Ragone plot showing power-energy characteristics of hybrid graphene-SWNT electrodes, and (vi) TEM images of multilayered graphene edges from graphene and graphene-SWNT hybrids, with interlayer spacing maps and FFT analysis. See DOI: 10.1039/c4nr00390j

Cohn, Adam P.; Oakes, Landon; Carter, Rachel; Chatterjee, Shahana; Westover, Andrew S.; Share, Keith; Pint, Cary L.

2014-04-01

373

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

374

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

375

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

376

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

PubMed

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

377

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

378

Variability of pavement noise benefit by vehicle type  

NASA Astrophysics Data System (ADS)

The Volpe Center Acoustics Facility, in support of the California Department of Transportation (Caltrans), is participating in a long-term study to assess several types of pavement for the purpose of noise abatement. On a four-mile stretch of a two-lane highway in Southern California, several asphalt pavement overlays are being examined. Acoustical, meteorological, and traffic data are collected in each pavement overlay section, where microphones are deployed at multiple distances and heights. Single vehicle pass-by events are recorded primarily for three vehicle types: automobiles, medium trucks, and heavy trucks. Data are analyzed to determine the noise benefit of each pavement as compared to the reference dense-graded asphaltic concrete (DGAC); this includes a modified Statistical Pass-By Index as well as average Lmax values for each vehicle type. In addition, 1/3-octave band data are examined. Automobiles and heavy trucks are the focus of this paper, where benefits due to pavement will be presented for three pavement types: open-graded asphaltic concrete (OGAC) of 75 mm thickness, open-graded asphaltic concrete (OGAC) of 30 mm thickness, and rubberized asphaltic concrete, Type O (open) (RAC) of 30 mm thickness. Average Lmax values and spectral data show that noise benefits due to pavement can vary by vehicle type.

Rochat, Judith L.; Read, David R.

2005-09-01

379

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

380

The Effect of Immediate Post-Training Active and Passive Recovery Interventions on Anaerobic Performance and Lower Limb Flexibility in Professional Soccer Players  

PubMed Central

The capacity to recover from intense training, competition and matches is considered an important determinant in soccer performance. At present, there is no consensus on the effect of post-training recovery interventions on subsequent training session. The aim of this study was to determine the effectiveness of active (12 min submaximal running and 8 min of static stretching) and passive recovery (20 min sitting on a bench) interventions performed immediately after a training session on anaerobic performances (CMJ, 20 m sprint and Balsom agility test) and lower limb flexibility 24 h after the training. During two experimental sessions, 31 professional soccer players participated in a randomized fully controlled trial design. The first session was designed to evaluate the player’s anaerobic performances and lower limb flexibility (pretest). After baseline measurements, participants performed a standardized soccer training during which heart rate and RPE were recorded to evaluate the training load. At the end of the training unit all players were randomly assigned to the active recovery group and the passive recovery group. A second experimental session was organized to obtain the posttest values. Players performed the same test, administered in the same order than in the first trial. No significant differences between groups were observed in heart rate and RPE. No significant effect due to recovery interventions was found on lower limb flexibility and anaerobic performances except CMJ that posttest value was significantly greater in the active recovery group than in the passive group (p < 0.05).

Rey, Ezequiel; Lago-Penas, Carlos; Casais, Luis; Lago-Ballesteros, Joaquin

2012-01-01

381

The effect of immediate post-training active and passive recovery interventions on anaerobic performance and lower limb flexibility in professional soccer players.  

PubMed

The capacity to recover from intense training, competition and matches is considered an important determinant in soccer performance. At present, there is no consensus on the effect of post-training recovery interventions on subsequent training session. The aim of this study was to determine the effectiveness of active (12 min submaximal running and 8 min of static stretching) and passive recovery (20 min sitting on a bench) interventions performed immediately after a training session on anaerobic performances (CMJ, 20 m sprint and Balsom agility test) and lower limb flexibility 24 h after the training. During two experimental sessions, 31 professional soccer players participated in a randomized fully controlled trial design. The first session was designed to evaluate the player's anaerobic performances and lower limb flexibility (pretest). After baseline measurements, participants performed a standardized soccer training during which heart rate and RPE were recorded to evaluate the training load. At the end of the training unit all players were randomly assigned to the active recovery group and the passive recovery group. A second experimental session was organized to obtain the posttest values. Players performed the same test, administered in the same order than in the first trial. No significant differences between groups were observed in heart rate and RPE. No significant effect due to recovery interventions was found on lower limb flexibility and anaerobic performances except CMJ that posttest value was significantly greater in the active recovery group than in the passive group (p < 0.05). PMID:23486836

Rey, Ezequiel; Lago-Peñas, Carlos; Casáis, Luis; Lago-Ballesteros, Joaquín

2012-03-01

382

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

383

23 CFR Appendix to Subpart F of... - Alternate Method of Determining the Color of Retroreflective Sign Materials and Pavement Marking...  

Code of Federal Regulations, 2010 CFR

...of Retroreflective Sign Materials and Pavement Marking Materials Appendix to Subpart...of Retroreflective Sign Materials and Pavement Marking Materials 1. Although...Specification Limits for Retroreflective Pavement Marking Material With CIE 2°...

2009-04-01

384

Pavement texture from high-speed laser for pavement management system  

Microsoft Academic Search

The locked-wheel skid trailer (ASTM E274) is commonly used to estimate the skid resistance of pavements in the United States. However, this method is very expensive and disturbs the traffic flows during the test. Hence, a correlation was developed between skid resistance or skid number (SN40R) values obtained using skid tester and the texture data or mean profile depth (MPD),

Jay N. Meegoda; Shengyan Gao; Sim Liu; Nicholas C. Gephart

2012-01-01

385

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

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

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.

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

2012-01-01

388

Possibilities of ground penetrating radar usage within acceptance tests of rigid pavements  

NASA Astrophysics Data System (ADS)

Within the road pavement acceptance tests, destructive as well as non-destructive tests of individual road layers are performed to verify the standard requirements. The article describes a method for providing quick, effective and sufficiently accurate measurements of both dowel and tie bar positions in concrete pavements, using a two-channel ground penetrating radar (GPR). Measurements were carried out in laboratory and in-situ conditions. A special hand cart for field measurements, set for the testing requirements, was designed. It was verified that following the correct measuring and assessment method, it is possible to reach accuracy of determining the in-built rebar up to 1 cm in vertical direction and up to 1.5 cm per 11.5 m of measured length in horizontal direction. In the in-situ tests, GPR identification of possible anomalies due to the phase of concrete pavement laying was presented. In the conclusion, a measurement report is mentioned. The standard requirements for the position of dowels and tie bars cover maximum possible deviation of the rebar position from the project documentation in vertical and horizontal direction, maximum deflection of rebar ends to each other, and maximum translation of rebar in the direction of its longitudinal axis.

Stryk, Josef; Matula, Radek; Pospisil, Karel

2013-10-01

389

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

390

Design Parameters for Two-Layered Pavement Systems.  

National Technical Information Service (NTIS)

This report presents the values of the modulus of elasticity and Poisson's ratio obtained for three base materials used in airfield pavement construction. These bases were constructed of sand, select base, and crushed rock. Each base was prepared to form ...

J. Nielsen

1964-01-01

391

An Iterative Layered Elastic Computer Program for Rational Pavement Design.  

National Technical Information Service (NTIS)

This study was conducted to develop a simple and easily operated computer program for the rational design of pavements. The program must yield results approximating those computed by the more sophisticated nonlinear finite element program. A linearly laye...

Y. T. Chou

1976-01-01

392

Microthesaurus of Vehicle Mobility, Environment, and Pavement Terms.  

National Technical Information Service (NTIS)

The terms in the microthesaurus cover three major areas of interest: Vehicle mobility, environment, and pavements, as related primarily to military research. Non-technical terms common to all subject areas in research and development are included to provi...

1975-01-01

393

Optimal Placement of Reflective Pavement Markers. Appendices C and D.  

National Technical Information Service (NTIS)

The project included an analytical optimization of the spacings for Snowplowable Raised Reflective Pavement Markers (RRPM's) for tangent sections of interstate highways and entrance and exit ramps (curves). The project also included a test driver study us...

H. T. Zwahlen

1985-01-01

394

Optimal Placement of Reflective Pavement Markers. Appendices A and B.  

National Technical Information Service (NTIS)

The project included an analytical optimization of the spacings for Snowplowable Raised Reflective Pavement Markers (RRPM's) for tangent sections of interstate highways and entrance and exit ramps (curves). The project also included a test driver study us...

H. T. Zwahlen

1985-01-01

395

Variability in Highway Pavement Construction. A Synthesis of Highway Practice.  

National Technical Information Service (NTIS)

This synthesis will be of interest to state department of transportation (DOT) construction, materials, statistical, specification, and inspection engineers; DOT research staff; pavement construction material suppliers; highway construction contractors; a...

C. S. Hughes

1996-01-01

396

Optimal Placement of Reflective Pavement Markers. Final Report.  

National Technical Information Service (NTIS)

The project included an analytical optimization of the spacings for Snowplowable Raised Reflective Pavement Markers (RRPM's) for tangent sections of interstate highways and entrance and exit ramps (curves). The project also included a test driver study us...

H. T. Zwahlen

1985-01-01

397

Permeable Pavement Demonstration at the Edison Environmental Center - Poster  

EPA Science Inventory

Poster for the SAB Review detailing the porous pavement parking lot project. The poster describes the design of the parking lot, the research components that were incorporated into the design, and the monitoring plan....

398

Investigation into Acrylic Paint Cracking (APC) on Asphaltic Pavements.  

National Technical Information Service (NTIS)

The objective of this effort was to investigate Acrylic Paint Cracking (APC) on asphaltic pavements and to identify an APC coating solution. The investigation consisted of: (1) Site visits to asphaltic airfields, roads, and parking lots, (2) Field testing...

C. D. Gaughen

2000-01-01

399

Tentative Pavement and Geometric Design Criteria for Minimizing Hydroplaning.  

National Technical Information Service (NTIS)

A comprehensive literature review, multi-state questionnaires, mathematical modeling, computer simulations, field testing and data correlations were used to establish tentative criteria relating to geometric and pavement surface texture and cross slope to...

B. M. Gallaway D. L. Ivey D. L. Woods H. E. Ross W. B. Ledbetter

1975-01-01

400

Pavement and Geometric Design Criteria for Minimizing Hydroplaning.  

National Technical Information Service (NTIS)

A comprehensive literature review, multistate questionnaire, mathematical modeling, computer simulation, field testings and data correlations were used to establish criteria relating to geometric and pavement surface characteristics to minimize highway hy...

B. M. Gallaway D. L. Ivey G. Hayes R. M. Olson W. B. Ledbetter

1979-01-01

401

Literature Review - Elastic Constants for Airport Pavement Materials.  

National Technical Information Service (NTIS)

A literature review was made to support an ongoing study to develop a method for evaluating airport pavements based on the layered elastic theory and using constants as determined from vibratory test results. The review covered the definitions and relatio...

J. L. Green

1978-01-01

402

Design of Full-Depth Asphalt Airfield Pavements.  

National Technical Information Service (NTIS)

This report provides fundamental concepts relative to the development of a theoretical design procedure for Full-Depth airfield pavements. The report is limited to those factors pertinent to the development of design thickness requirements to prevent load...

M. W. Witczak

1972-01-01

403

Revised Procedure for Pavement Design under Seasonal Frost Conditions.  

National Technical Information Service (NTIS)

This report presents engineering guidance and design criteria for pavements at Army and Air Force facilities in seasonal frost areas. Design methods for controlling surface roughness and loss of subgrade strength during thawing petiods are provided. Crite...

R. L. Berg T. C. Johnson

1983-01-01

404

Durability and Retro-Reflectivity of Pavement Markings, Synthesis Study.  

National Technical Information Service (NTIS)

Waterborne paints are used to paint pavement markings (edgelines and centerlines) to provide guidance for motorists. The painted markings need to be repainted periodically as their retro-reflectivity deteriorates. The Indiana Department of Transportation ...

Y. Jiang

2008-01-01

405

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

406

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

407

Microwave methods enable energy savings in restoration of highway pavements  

Microsoft Academic Search

Hot in-place recycling of asphalt pavement by a method which utilizes microwave energy in combination with hot-engine exhaust gases has been demonstrated to be technically and economically feasible. The process saves both energy and materials compared with conventional hot-mix recycling methods involving removal of old paving and reprocessing at hot-mix plants. Applications for microwave pavement heating include repair of cracks,

M. R. Jeppson; F. J. Smith

1983-01-01

408

Flexible Pipe Technology.  

National Technical Information Service (NTIS)

The conference proceedings contain 12 papers. The topics covered are: Technology, products and offshore applications; Steel reinforced elastomer pipes - Design approach and performance characteristics; Flexible pipe installation techniques; Gullfaks ''A''...

1986-01-01

409

Factors influencing PM 10 emissions from road pavement wear  

NASA Astrophysics Data System (ADS)

Accelerated pavement wear is one of the major environmental disadvantages of studded tyres in northern regions and results in increased levels of PM 10. Measurements of PM 10 in a road simulator hall have been used to study the influence of pavement properties, tyre type and vehicle speed on pavement wear. The test set-up included three different pavements (one granite and two quartzite with different aggregate sizes), three different tyre types (studded, non-studded, and summer tyres) and different speeds (30-70 km h -1). The results show that the granite pavement was more prone to PM 10 production compared to the quartzite pavements. Studded winter tyres yield tens of times higher PM 10 concentrations compared to non-studded winter tyres. Wear from summer tyres was negligible in comparison. It was also shown that wear is strongly dependent on speed; every 10 km h -1 increase yielded an increase of the PM 10 concentration of 680 ?g m -3 in one of the simulator experiments.

Gustafsson, Mats; Blomqvist, Göran; Gudmundsson, Anders; Dahl, Andreas; Jonsson, Per; Swietlicki, Erik

410

Influence of pavement condition on horizontal curve safety.  

PubMed

Crash statistics suggest that horizontal curves are the most vulnerable sites for crash occurrence. These crashes are often severe and many involve at least some level of injury due to the nature of the collisions. Ensuring the desired pavement surface condition is one potentially effective strategy to reduce the occurrence of severe accidents on horizontal curves. This study sought to develop crash injury severity models by integrating crash and pavement surface condition databases. It focuses on developing a causal relationship between pavement condition indices and severity level of crashes occurring on two-lane horizontal curves in Texas. In addition, it examines the suitability of the existing Skid Index for safety maintenance of two-lane curves. Significant correlation is evident between pavement condition and crash injury severity on two-lane undivided horizontal curves in Texas. Probability of a crash becoming fatal is appreciably sensitive to certain pavement indices. Data suggested that road facilities providing a smoother and more comfortable ride are vulnerable to severe crashes on horizontal curves. In addition, the study found that longitudinal skid measurement barely correlates with injury severity of crashes occurring on curved portions. The study recommends exploring the option of incorporating lateral friction measurement into Pavement Management System (PMS) databases specifically at curved road segments. PMID:23298704

Buddhavarapu, Prasad; Banerjee, Ambarish; Prozzi, Jorge A

2013-03-01

411

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

412

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

413

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

414

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

415

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

416

Post-Glacial Ant Generated Desert Pavements in Southeastern Oregon  

NASA Astrophysics Data System (ADS)

Desert pavements typically require thousands to tens of thousands of years to reach a high level of development. In a pluvial lake valley in Southeastern Oregon I have observed harvester ants creating desert pavement-like features in less than two months. The summer lake basin is a fairly simple sedimentary system. In the eastern half of the basin, the basaltic bedrock is buried under tens of meters of alluvial deposits which lie beneath an approximately ten meter thick dune sheet. The dune sands are noticably different in grainsize and chemistry than the fine component of the alluvial deposits. The dunes began to form at the end of the last pluvial interval (Allison 1980) and continue to be active today. Roughly one fourth of the total area of the dune sheet is mantled with desert pavement, consisting of very coarse sand and fine pebbles (1-8 mm diameter). The dune sand is very fine grained with a considerable amount of silt and minimal clay. It forms thin (2-20 cm thick) well developed Av horizons beneath the desert pavement. Owyhee harvester ants (Pogonomyrmex owyheei) in the area use pebbles of the same size and petrology as the desert pavements to construct their hills. For the ants the closest source of these pebbles is often the alluvium, ten meters below the anthill, rather than in a desert pavement deposit at some distance away overland. An experiment conducted between June and August 1999 demonstrated that the ants rebuild their hills with newly excavated pebbles. When the colonies die off after 5-25 years, the pebbles are stranded at the surface. Processes such as those described by Haff and Werner (1996), where jackrabbits and birds were observed kicking desert pavement clasts aross the ground serve to redistribute the pebbles across the surface of the sand dunes. The sand dunes have been forming over an 8000 year period. Based on anthill-regrowth measurements, the lifespan of an individual colony of harvester ants leads to the excavation of only enough pebbles to cover a two meter square area with desert pavement. This study has determined the quantity of desert pavement currently present at the surface of the sand dunes, and the timescale over which ants can excavate pebbles from the alluvium. The episodic nature of ant colony activity remains to be fully incorporated into the study of desert pavement, usually thought of as a static landform.

Leonard, K. C.

2001-12-01

417

Study of Factors Affecting Roughness Progression on Portland Cement Concrete Pavements in Kansas.  

National Technical Information Service (NTIS)

Portland Cement Concrete Pavements (PCCP) with favorable as-constructed smoothness and lower rates of roughness progression are expected to have longer service lives. This study was done to estimate pavement damage due to dynamic wheel loads generated for...

J. Hancock M. Akhter M. Hossain

2004-01-01

418

Development of a Real-Time Transverse Pavement Profile Measurement System: Summary Report.  

National Technical Information Service (NTIS)

The Texas Department of Transportation (TxDOT) has been using a five-sensor rut bar system that uses measurements made with ultrasonic sensor technology to automatically collect pavement rutting for Pavement Management Information System (PMIS) purposes. ...

R. S. Walker

2006-01-01

419

State-of-the-Art Studies/Preliminary Work Scopes. Task B. Pavement Maintenance Costs.  

National Technical Information Service (NTIS)

Pavement maintenance cost is one of the three major components of the total life cycle cost for a specific highway segment. The capability of accurately estimating pavement maintenance cost depends directly on the quality of the available maintenance data...

H. J. Chen J. Perl M. W. Mirza

1987-01-01

420

Geocomposite Capillary Barrier Drain for Limiting Moisture Changes in Pavement Subgrades and Base Courses.  

National Technical Information Service (NTIS)

This project determined the effectiveness of a geocomposite capillary barrier drain (GCBD) system in preventing pavement damage by controlling moisture movement in pavement subgrade and base course. A number of geotextiles were evaluated for their suitabi...

K. S. Henry J. C. Stormont

2002-01-01

421

Construction and Preliminary Monitoring of the Georgetown, Texas Precast Prestressed Concrete Pavement.  

National Technical Information Service (NTIS)

After completion of a feasibility study which examined the viability of using precast concrete panels to expedite pavement construction, FHWA and TxDOT funded an implementation project to construct a precast concrete pavement pilot project to test the con...

D. K. Merritt B. F. McCullough N. H. Burns

2002-01-01

422

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 ...

423

Engineering Properties of Stabilized Subgrade Soils for Implementation of the AASHTO 2002 Pavement Design Guide.  

National Technical Information Service (NTIS)

A comprehensive laboratory study was undertaken to determine engineering properties of cementitiously stabilized common subgrade soils in Oklahoma for the design of roadway pavements in accordance with the AASHTO 2002 Mechanistic-Empirical Pavement Design...

M. M. Zaman N. N. Khoury P. Solanki

2009-01-01

424

Design of Continuously Reinforced Concrete Pavements Using Glass Fiber Reinforced Polymer Rebars.  

National Technical Information Service (NTIS)

This report investigates the effects on stress development in pavement and on critical design factors from substituting glass fiber reinforced polymer (GFRP) reinforcement for conventional steel reinforcement in continuously reinforced concrete pavements ...

J. H. Choi R. H. Chen

2005-01-01

425

Over the Edge and Back: What to Do If You Drive Off the Pavement Edge  

MedlinePLUS

AAA Foundation for Traffic Safety Over the Edge and Back What to do if you drive off ... fatal relative to other crashes on similar roads. AAA Foundationfor Traffic Safety Pavement edge drop-off “ Pavement ...

426

Winter Tenting of Highway Pavements. Test Program and Discussion of Causes and Mechanisms.  

National Technical Information Service (NTIS)

Tenting consists of localized frost heaving in the immediate vicinity of transverse pavement cracks. It produces a highly irregular riding surface, leads to premature pavement-surface deterioration, occurs on highways designed for high traffic volumes and...

M. A. Kestler, A. S. Krat, G. E. Roberts

2000-01-01

427

Evaluation of Three Porous Pavement Systems in a Newly Constructed Parking Lot  

EPA Science Inventory

This project examines porous pavement systems in a newly constructed parking lot next to Building 205 at the Edison Environmental Center. Porous pavement systems are one means of promoting environmental sustainability through stormwater runoff reduction. This project examines t...

428

Materials Characterization and Analysis of the Marquette Interchange HMA Perpetual Pavement.  

National Technical Information Service (NTIS)

This project focused on the characterization of materials used to construct the Hot Mix Asphalt (HMA) perpetual pavement within the Marquette Interchange and on the analysis of collected pavement response data to investigate the interactions between mater...

A. Coenen C. Williams H. Titi J. A. Crovetti R. E. Mohanned

2008-01-01

429

Criteria for asphalt-rubber concrete in civil airport pavements: Mixture design  

NASA Astrophysics Data System (ADS)

A mixture design procedure is developed to allow the use of asphalt-rubber binders in concrete for flexible airport pavement. The asphalt-rubber is produced by reacting asphalt with ground, scrap tire rubber to produce the binder for the asphalt-rubber concrete. Procedures for laboratory preparation of alsphalt-rubber binders using an equipment setup that was found by researchers to produce laboratory binders with similar properties to field processes are included. The rubber-asphalt concrete mixture design procedure includes adjustments to the aggregate gradation to permit space for the rubber particles in the asphalt-rubber binder as well as suggested mixing and compaction temperatures, and compaction efforts. While the procedure was used in the laboratory to successfully produce asphalt-rubber concrete mixtures, it should be evaluated in the field to ensure that consistent results can be achieved in a production environment.

Roberts, F. L.; Lytton, R. L.; Hoyt, D.

1986-07-01

430

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

431

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

432

RESEARCH ON STEEL FIBER REINFORCED CONCRETE PAVEMENT FOR ORTHOTROPIC STEEL DECK AS A COUNTERMEASURE FOR FATIGUE  

Microsoft Academic Search

This paper describes ongoing studies about application of Steel Fiber Reinforced Concrete (SFRC) pavement for existing orthotropic steel deck as a countermeasure for fatigue problems. Public Works Research Institute (PWRI) and several companies are now conducting joint researches on repair\\/reinforcement methods including SFRC pavement. In order to evaluate durability of the pavement, strength tests and fatigue tests under negative bending

Jun Murakoshi; Naoki Yanadori; Hironori Ishii

433

The clogging behaviour and treatment efficiency of a range of porous pavements  

Microsoft Academic Search

This paper presents the findings of a laboratory investigation into the clogging behaviour of three different porous pavements that were most representative of the available range and their pollutant removal efficiency over time. These pavements were monolithic Porous Asphalt (PA), Permapave (PP), and modular Hydrapave (HP). The pavements were dosed with a semi-synthetic stormwater mixture over a continuous period of

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

434

23 CFR 971.208 - Federal lands pavement management system (PMS).  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Federal lands pavement management system (PMS). 971.208...Systems § 971.208 Federal lands pavement management system (PMS). In addition...concepts described in the AASHTO's âPavement Management Guide.â 1 1...

2009-04-01

435

23 CFR 972.208 - Federal lands pavement management system (PMS).  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Federal lands pavement management system (PMS). 972.208...Systems § 972.208 Federal lands pavement management system (PMS). In addition...concepts described in the AASHTO's âPavement Management Guide.â2 2...

2009-04-01

436

23 CFR 973.208 - Indian lands pavement management system (PMS).  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Indian lands pavement management system (PMS). 973.208...Systems § 973.208 Indian lands pavement management system (PMS). In addition...concepts described in the AASHTO's âPavement Management Guide.â 1 1...

2009-04-01

437

23 CFR 973.208 - Indian lands pavement management system (PMS).  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Indian lands pavement management system (PMS). 973.208...Systems § 973.208 Indian lands pavement management system (PMS). In addition...concepts described in the AASHTO's âPavement Management Guide.â 1 1...

2010-04-01

438

23 CFR 971.208 - Federal lands pavement management system (PMS).  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Federal lands pavement management system (PMS). 971.208...Systems § 971.208 Federal lands pavement management system (PMS). In addition...concepts described in the AASHTO's âPavement Management Guide.â 1 1...

2010-04-01

439

23 CFR 972.208 - Federal lands pavement management system (PMS).  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Federal lands pavement management system (PMS). 972.208...Systems § 972.208 Federal lands pavement management system (PMS). In addition...concepts described in the AASHTO's âPavement Management Guide.â2 2...

2010-04-01

440

Striated boulder pavements within glaciomarine diamicts of the Yakataga Formation, Middleton Island, Alaska  

Microsoft Academic Search

The presence of striated boulder pavements in glacial sequences is often cited as evidence of transport and deposition by grounded glacier ice. However, recent reports show that striated pavements also form in non-glacial environments by the abrasion of boulder lag surfaces by floating glacier and seasonal ice. Several striated boulder pavements are identified within Early Pleistocene upper Yakataga Formation sediments

Eyles

1985-01-01

441

A numerical approach to evaluate the risk of differential surface icing on pavements with insulated sections  

Microsoft Academic Search

This paper presents the results of a numerical study on the differential icing risk at the surface of pavements with insulated sections in the Province of Quebec, Canada. Differential icing situations occur when slippery conditions form on the surface of insulated pavement sections while adjacent conventional pavement sections maintain dry surface conditions. A heat transfer model that considers the climate

Jean Côté; Jean-Marie Konrad

2005-01-01

442

Auto-synchronized laser scanning range sensor for thermoplastic pavement marking material thickness measurement  

Microsoft Academic Search

Pavement marking materials provide delineation on highways around the world. The condition of the marking materials is very important for the driver's safety as well as the comfort and the driving expenses. Currently thermoplastic pavement marking materials (TPMM) are widely used in states. Measuring the thickness of TPMM on pavement is an essential index to monitor the contractors, calculate durability

Wei Sun; Xuemin Chen; Yuanhang Chen; Aditya Ekbote; Richard Ce Liu

2006-01-01

443

High Performance Bottom-Gate-Type Amorphous InGaZnO Flexible Transparent Thin-Film Transistors Deposited on PET Substrates at Low Temperature  

NASA Astrophysics Data System (ADS)

The InGaZnO channel layer of bottom-gate-type flexible transparent thin-film transistors was deposited on polyethylene terephthalate substrates using a magnetron radio frequency cosputter system with a single InGaZnO target. The composition of the InGaZnO channel layer was controlled by sputtering at various Ar/O2 gas ratios. A 15-nm-thick SiO y insulator film was used to passivate the InGaZnO channel layer. Much better performances of the passivated devices were obtained, which verified the passivation function. To study the bending stability of the resulting flexible transparent thin-film transistors, a stress test with a bending radius of 1.17 cm for 1,500 s was carried out, which showed a variation in the effective filed-effect mobility and the threshold voltage of the unpassivated and passivated devices being maintained within 10 and 8%, respectively.

Lee, Hsin-Ying; Ye, Wan-Yi; Lin, Yung-Hao; Lou, Li-Ren; Lee, Ching-Ting

2014-01-01

444

Flexible dye solar cells  

Microsoft Academic Search

Strategies towards flexible solid state solar cells based on nanocrystalline titanium oxide and organic hole conductor were investigated. For the flexible cell geometry a metal foil was used as substrate and a semi-transparent gold layer as counter electrode which allows light transmission (back illumination). The device performance of solid state cells based on SnO2:F coated glass on the one hand

Nathalie Rossier-Iten; Toby B. Meyer; Jessica Krueger; Michael Graetzel

2004-01-01

445

Flexible composites  

Microsoft Academic Search

This paper reviews the linear and non-linear elastic behaviour of flexible composites, which are based on elastomeric polymers and exhibit a usable range of deformation much larger than those of conventional thermosetting or thermoplastic polymer-based composites. The types of flexible composites examined are cord\\/rubber composites, coated fabrics and composites containing wavy fibres. The classical lamination theory forms the basis of

Tsu-Wei Chou

1989-01-01

446

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

447

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

448

Ecophysiological studies in Kalanchoë porphyrocalyx (Baker) and K. miniata (Hils et Bojer), two species performing highly flexible CAM.  

PubMed

Preceding results, based on the determination of stable carbon isotope composition (?13C) of leaf tissues from various Kalanchoë species, suggested a close coincidence between the photosynthetic flexibility of the species and their habitat, life form and taxonomic position within the genus. The ability to shift from C3-to Crassulacean Acid Metabolism (CAM)-type of photosynthesis seemed to concern in particular the more ancestral species in the genus and to be linked to epiphytism and changing climatic situations. For deeper insights into these interrelationships, physiological studies in controlled conditions were carried out on K. miniata and K. porphyrocalyx. These two species differ by their habitat preference and life form. Measurements were conducted on CO2 exchange patterns, day/night fluctuation of malate content in the leaves and 'capacity' of phosphoenolpyruvate carboxylase (PEPC). The results show that the 2 species can be considered as 'facultative' CAM plants, with very high flexibility in their photosynthetic behaviour. The decrease in water availability seems to be a major factor triggering the shift from C3 to the CAM mode. In K. miniata, 21 days of drought depressed CO2 uptake to the level of CAM idling whereas in K. porphyrocalyx, CO2 exchange was considerably more resistant. At least for K. miniata, short-day treatment was found to be a further CAM-inducing factor. The results are discussed in terms of their ecophysiological significance under the environmental conditions of the sites where the investigated species naturally grow. PMID:24271531

Brulfert, J; Ravelomanana, D; Güçlü, S; Kluge, M

1996-07-01

449

Synthesis and photocatalytic performance of titanium dioxide nanofibers and the fabrication of flexible composite films from nanofibers.  

PubMed

Titanium dioxide nanofibers were synthesized and applied in flexible composite films that are easy to handle and recycle after use. The nanofibers were obtained in a multi-step procedure. First, sodium titanate nanofibers were prepared from TiO2 nanoparticles through the alkali hydrothermal method. In the next step, sodium hydrogen titanate nanofibers were made by washing the sodium titanate nanofibers in HCl solution. Finally, the sodium hydrogen titanate nanofibers were transformed to TiO2 anatase nanofibers by calcination in air. The photocatalytic activity of TiO2 anatase nanofibers were evaluated and compared to a TiO2 nanoparticle catalyst by decomposing methyl orange dye in aqueous solutions. The achieved reaction rate constant of TiO2 anatase nanofibers was comparable to that of Degussa P25. Paper-like flexible composite films were prepared by co-filtrating aqueous dispersions of TiO2 catalyst materials and cellulose. The composite films made from the nanofibers exhibit better mechanical integrity than those of the nanoparticle-cellulose composites. PMID:22629970

Wu, Ming-Chung; Tóth, Geza; Sápi, András; Leino, Anne-Riikka; Kónya, Zoltán; Kukovecz, Akos; Su, Wei-Fang; Kordás, Krisztián

2012-02-01

450

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

451

Solution-processed high-performance flexible 9, 10-bis(phenylethynyl)anthracene organic single-crystal transistor and ring oscillator  

NASA Astrophysics Data System (ADS)

Organic semiconductor of 9, 10-bis(phenylethynyl)anthracene (BPEA) single crystal ribbon with ultra-long length has been prepared by solution drop casting method, where the growth direction was controlled with the seed crystal. The BPEA single crystal ribbon based field-effect transistors show high hole mobility up to 3.2 cm2/V·s, and the inverters exhibited the highest gain of 92. The complex device such as 5-stage ring oscillator consisting of 10 transistors was also constructed on a single crystal ribbon. This straightforward methodology was applied to fabricate plastic transistors on the flexible substrate, showing high performance even after repeatedly bending of 300 times.

Cai, Xiaozhou; Ji, Deyang; Jiang, Lang; Zhao, Guangyao; Tan, Jiahui; Tian, Guofeng; Li, Jingze; Hu, Wenping

2014-02-01

452

Flexible Circuits  

NASA Technical Reports Server (NTRS)

Adflex Solutions, Inc.'s flexible circuits may be molded to the shape of a chassis for bulk reduction. Particularly valuable when circuitry must be moved. They are produced by combining a plastic film, a metallic conductor and an adhesive. One adhesive, LARC-TPI, developed by the Langley Research Center, is a thermoplastic polyimide resin used to produce laminates by Rogers Corporation. It can be processed at a lower temperature, has good moisture resistance and excellent adherence. It is used to bond film to copper foil conductor materials in flexible circuits. The circuits have both aerospace and commercial applications.

1986-01-01

453

Piping Flexibility  

NASA Technical Reports Server (NTRS)

A NASA computer program aids Hudson Engineering Corporation, Houston, Texas, in the design and construction of huge petrochemical processing plants like the one shown, which is located at Ju'aymah, Saudi Arabia. The pipes handling the flow of chemicals are subject to a variety of stresses, such as weight and variations in pressure and temperature. Hudson Engineering uses a COSMIC piping flexibility analysis computer program to analyze stresses and unsure the necessary strength and flexibility of the pipes. This program helps the company realize substantial savings in reduced engineering time.

1978-01-01

454

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.

455

Facile Synthesis of Graphite/PEDOT/MnO2 Composites on Commercial Supercapacitor Separator Membranes as Flexible and High-Performance Supercapacitor Electrodes.  

PubMed

A facile and low-cost method is presented to synthesize graphite/PEDOT/MnO2 composites with controlled network structures on commercial supercapacitor separator (CSS) membranes for high-performance supercapacitors, in which pencil lead and a cellulose-based commercial supercapacitor separator membrane were applied as the graphite source and the flexible substrate, respectively. The dependence of PEDOT and MnO2 loading on the structural formation, the electrochemical performance of the hybrid electrode, and the formation mechanism of MnO2 nanowires are systematically investigated. The optimized electrode possesses a high areal capacitance of 316.4 mF/cm(2) at a scan rate of 10 mV/s and specific capacitance of 195.7 F/g at 0.5 A/g. The asymmetric supercapacitor device assembled using optimized CSS/Graphite/PEDOT/MnO2 electrode and activated carbon electrode exhibits a high energy density of 31.4 Wh/kg at a power density of 90 W/kg and maintains 1 Wh/kg at 4500 W/kg. After 2000 cycles, the device retains 81.1% of initial specific capacitance, and can drive a mini DC-motor for ca. 10 s. The enhanced capability of the CSS-based graphite/PEDOT/MnO2 network electrode has high potential for low-cost, high-performance, and flexible supercapacitors. PMID:24905133

Tang, Pengyi; Han, Lijuan; Zhang, Li

2014-07-01

456

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

457

The behavior of a slag base pavement structure at P39/1, Erasmia under heavy vehicle simulator loading  

NASA Astrophysics Data System (ADS)

An evaluation of unbound slag as a basecourse material using the Heavy Vehicle Simulator (HVS) was undertaken. Two HVS tests were performed on site P39/1 and with these tests it is possible not only to evaluate slag as a basecourse material, but also to compare it with a good quality crushed-stone base. It was felt that these tests would give further information on the possible use of slag as a basecourse material in Category A roads. A description of the HVS tests on this slag base pavement is given. The test results were evaluated using mechanistic analysis techniques. The behavior of the pavement structure is described and analyzed, and dry conditions are compared with wet conditions. Finally, general recommendations are made on the use of high standard slag bases.

Horak, E.; Maree, J. H.

1982-02-01

458

Effects of an 8-week multimodal exercise program on strength, flexibility, and golf performance in 55- to 79-year-old men.  

PubMed

Substantial research has indicated the beneficial effect of physical activity on physical fitness and activities of daily living in older adults, but none have investigated the effects on performance of recreational activities. This investigation studied the effect of an exercise program on fitness and golf-clubhead speed in older men. Thirty-one golfers (mean age 65.1 +/- 6.2 years) were randomly assigned to a treatment (n = 19) or control (n = 12) group. The treatment group completed an 8-week strength and flexibility program. Assessments included 10-RM muscle strength; selected range-of-motion (ROM) measurements; and golf-clubhead speed (CHS). ANCOVA revealed significant differences between groups (p <.005) for all strength measurements and several ROM measurements. CHS was significantly different (p <.05) between groups after the intervention. Mean CHS improved from 85.0 to 87.1 miles/hr (136.8 to 140.2 km/hr). These results indicate that a strength and flexibility program can improve golf performance in older adults. PMID:15223883

Thompson, Christian J; Osness, Wayne H

2004-04-01

459

Pavement Joint Sealant Specifications—Past, Present, and Future  

Microsoft Academic Search

Portland cement concrete (PCC) began to be used as a surface or wearing course for pavements in the United States in the early 1900s. The joint sealant or filler materials used during this early construction period were typically sand, tar paper, coal-tar pitch, asphaltic compounds, or wooden blocks. Material specifications for these early joint filler materials were nonexistent. The main

Larry N. Lynch; Donald J. Janssen

1998-01-01

460

Use of Scrap Rubber in Asphalt Pavement Surfaces.  

National Technical Information Service (NTIS)

Scrap tire rubber was mixed into an asphalt concrete wearing course to study the effect of ice disbonding from the pavement surface under traffic. Rubber contents of 0, 3, 6, and 12% by weight were studied. Initial laboratory ice disbonding test results l...

R. A. Eaton R. J. Roberts R. R. Blackburn

1991-01-01

461

Evaluation of a Hot Mix Asphalt Perpetual Pavement.  

National Technical Information Service (NTIS)

In 2003, WisDOT constructed two perpetual pavement test sections on the entrance ramp to I-94 from the Kenosha Safety and Weigh Station Facility in Southeastern WI. Test section 1 (TS1) HMA layers were constructed as follows: 2-in surface layer (PG 76-28,...

B. Bischoff I. Battaglia J. Ryan S. Reichelt

2010-01-01

462

Texas Perpetual Pavements: Experience Overview and the Way Forward.  

National Technical Information Service (NTIS)

Since 2001, the State of Texas has been designing and constructing perpetual pavements on some of its heavily trafficked highways where the expected 20-year truck-traffic estimate of 18 kip ESALs is in excess of 30 million. To date, there are 10 in-servic...

L. F. Walubita T. Scullion W. Liu

2010-01-01

463

Evaluation of Concrete Pavement Repair Using Precast Technology in Virginia  

Microsoft Academic Search

The Virginia Transportation Research Council has recently evaluated the use of precast con- crete patches for repairing jointed concrete pavement in Virginia. Six patches were placed: three had dowels cast into them during fabrication, and three had dowels inserted in place (dowel bar retrofit). Fabrication and placement were documented. The load transfer efficiency at the joints and the ride quality

Shabbir Hossain; Celik Ozyildirim

464

Investigation of Asphalt Pavement Analyzer Testing Program in Nebraska.  

National Technical Information Service (NTIS)

The asphalt pavement analyzer (APA) has been widely used to evaluate hot-mix asphalt (HMA) rutting potential in mix design and quality control quality assurance (QC-QA) applications, because the APA testing and its data analyses are relatively simple, rap...

M. Hong Y. R. Kim

2008-01-01

465

Management of Vegetation on the Pavement Edge and Adjacent Shoulder.  

National Technical Information Service (NTIS)

Herbicides were applied to the pavement edge and adjoining shoulder on two-lane highways FM 331 near Bellville on June 6, 1991, and on FM 1087 near Nacogdoches, Texas, on June 3, 1991, to evaluate their influence on vegetation control. Herbicides used inc...

R. E. Meyer C. L. Benner W. G. McCully

1995-01-01

466

Deteriorated pavements due to the alkali–silica reaction  

Microsoft Academic Search

Deteriorated concrete pavements from three regions in Argentina were studied. The aim was to evaluate aggregate constituents, especially the presence of deleterious components, determine what reaction products had developed, and find the main causes of the deterioration based on the petrographic study of the concrete. Thin sections were analyzed with a petrographic microscope to evaluate microcracking, characteristics of the aggregate–cement

S. A Marfil; P. J Maiza

2001-01-01

467

Prediction of Wet-Pavement Skid Resistance and Hydroplaning Potential  

Microsoft Academic Search

The current means of predicting the skid resistance of a wet pavement and the speed at which hydroplaning would occur are based on empirical models or relationships derived from experimental studies. These models and relationships are applicable only for the conditions specified, and extrapolations beyond the applicability range of parameters (e.g., vehicle speed, tire load, tire inflation pressure, water film

Ghim Ping Ong; T F Fwa

2007-01-01

468

Stabilized Pavements for ALRS (Alternate Launch and Recovery Surfaces).  

National Technical Information Service (NTIS)

An 'ALRS Stabilized Material Pavement Analysis System' (SPAS) is proposed. An 'intact slab' approach based on ILLI-PAVE analyses and Meyerhof ultimate concepts is recommended. The study of the WES Test Section data indicated the validity of SPAS and facil...

M. R. Thompson R. R. Costigan

1985-01-01

469

Summary of Experimental Concrete Pavements in New York.  

National Technical Information Service (NTIS)

The report summarizes a 22-year study of concrete pavement design features. It included construction of a test road with numerous variables, two roads with several major design changes, and several roads among the first to incorporate a major change in lo...

J. M. Vyce

1988-01-01

470

Implementation of an Automated Rating Procedure for Pavement Surface Roughness.  

National Technical Information Service (NTIS)

The study on the implementation of a Rating Procedure for Pavement Surface Roughness was divided into three tasks. The first task involved the automation of the collection and processing of roughness data. The task involved using a microprocessor-based da...

G. F. Hayhoe J. C. Wambold W. H. Park

1982-01-01

471

Sensing and Signal Processing for a Distributed Pavement Monitoring System  

Microsoft Academic Search

Estimation of road profile parameters and detection of road pavement failures using in-vehicle sensors such as vertical accelerometers or position sensors is of immense value in a futuristic distributed highway monitoring system. In this paper, a novel road elevation profile model, well suited for analysis using statistical signal processing tools, is developed to characterize road features. We then apply maximum

M. Ndoye; S. V. Vanjari; H. Huh; J. V. Krogmeier; D. M. Bullock; C. A. Hedges; A. Adewunmi

2006-01-01

472

Portland Cement Concrete Pavement Recycling, I-84, Waterbury - Final Report.  

National Technical Information Service (NTIS)

A 1000' section on I-84 WB in Waterbury was reconstructed in 1979-80, using recycled PCC derived from the original pavement. Upon completion, a semiannual series of visual observations and friction tests was initiated, continuing into early 1986. Developm...

G. A. Ganung D. A. Larsen

1986-01-01

473

Mathematical model of frost heave and thaw settlement in pavements  

Microsoft Academic Search

Since 1975 the U.S. Army Corps of Engineers, the Federal Highway Administration and the Federal Aviation Administration have been working cooperatively to develop a mathematical model to estimate frost heave and thaw weakening under various environmental conditions and for various pavement designs. A model has been developed. It is a one-dimensional representation of vertical heat and moisture flux. It is

Gary L. Guymon; Richard L. Berg; Theodore V. Hromadka

1993-01-01

474

Revised procedure for pavement design under seasonal frost conditions  

Microsoft Academic Search

This report presents engineering guidance and design criteria for pavements at Army and Air Force facilities in seasonal frost areas. Design methods for controlling surface roughness and loss of subgrade strength during thawing periods are provided. Criteria for using thermal insulating materials and membrane encapsulated soil layers in seasonal frost areas are presented. Six design examples are included.

R. L. Berg; T. C. Johnson

1983-01-01

475

Revised procedure for pavement design under seasonal frost conditions  

NASA Astrophysics Data System (ADS)

This report presents engineering guidance and design criteria for pavements at Army and Air Force facilities in seasonal frost areas. Design methods for controlling surface roughness and loss of subgrade strength during thawing periods are provided. Criteria for using thermal insulating materials and membrane encapsulated soil layers in seasonal frost areas are presented. Six design examples are included.

Berg, R. L.; Johnson, T. C.

1983-09-01

476

Tire/Pavement Noise Study for Arkansas APA.  

National Technical Information Service (NTIS)

The purpose of this paper is to present the results of noise testing accomplished by the National Center for Asphalt technology using a close-proximity noise trailer. The paper discusses the nature of tire/pavement noise and the results of testing selecte...

B. Waller D. I. Hanson R. S. James

2005-01-01

477

Implementation of Warm-Mix Asphalt Mixtures in Nebraska Pavements.  

National Technical Information Service (NTIS)

The primary objective of this research is to evaluate the feasibility of several WMA mixtures as potential asphalt paving mixtures for Nebraska pavements. To that end, three well-known WMA additives (i.e., Sasobit, Evotherm, and Advera synthetic zeolite) ...

H. Ban J. Zhang Y. R. Kim

2012-01-01

478

The Edison Environmental Center Permeable Pavement Site - slides  

EPA Science Inventory

This is a presentation for a second Community Outreach Event called "Chemistry Works!" at West Windsor Public Library on Saturday, November 5th. It will review the permeable pavement research project at the Edison Environmental center. Besides slide persentation, two demo units w...

479

Use of crushed concrete products in Minnesota pavement foundations. Final report, 1987-1994  

SciTech Connect

The report reviews eleven field and laboratory studies that have been performed to address concerns about the use of recycled concrete aggregate in pavement foundations. Performance concerns have centered on the possible impairment of drainage systems by deposits of calcium carbonate precipitate and other fines derived from the recycled concrete base materials. Environmental concerns have focused on the relatively high pH of the effluent produced by drainage systems that remove water from ungreated recycled concrete aggregate foundation layers. The studies considered in the report demonstrate that all recycled concrete aggregates are capable of producing various amounts of precipitate, with the precipitate potential being directly related to the amount of freshly exposed cement mortar surface. It appears that selective grading and blending with virgin aggregates are techniques that should significantly reduce precipitate potential. One study suggests that washing recycled concrete products will reduce accumulations of crusher dust and other fines in and around the pavement drains. Others indicate that the use of filter fabrics with sufficiently high initial permittivity will allow the accumulation of precipitate and other fines without significant impairing drainage function. The report discusses study results related to environmental concerns and provides recommendations for revisions to current specifications.

Synder, M.B.

1995-03-01

480

Influence of the deposition temperature on the structure and performance of tris(8-hydroxyquinoline) aluminum based flexible organic light-emitting devices  

NASA Astrophysics Data System (ADS)

Based on indium tin oxide (ITO)/ N, N'diphenyl- N- N'-di( m-tdyl) benzidine (TPD)/Alq 3/Al structure, flexible OLEDs on polyethylene terephthalate (PET) substrates were fabricated by physical vapor deposition (PVD) method. Tris(8-hydroxyquinoline)aluminum (Alq 3) films were deposited at 90, 120 and 150 °C to examine the influence of the deposition temperature on the structure and performance of OLEDs. Electroluminescence (EL) spectra and current-voltage-luminance ( I- V- L) characteristics of the OLEDs were examined. It was found that the device fabricated at a high temperature had a higher external efficiency and longer lifetime. Atomic force microscope (AFM) was adopted to characterize the surface morphology of ITO/TPD/Alq 3. The higher uniform morphology of the Alq 3 formed at high temperature might contribute to the performance improvement of the OLEDs.

Wang, Guang Feng; Tao, Xiao Ming; Huang, Hong Min

2007-03-01

481

An assessment of the skid resistance effect on traffic safety under wet-pavement conditions.  

PubMed

Pavement-tire friction provides the grip that is required for maintaining vehicle control and for stopping in emergency situations. Statistically significant negative correlations of skid resistance values and wet-pavement accident rates have been found in previous research. Skid resistance measured with SCRIM and crash data from over 1750km of two-lane rural roads in the Spanish National Road System were analyzed to determine the influence of pavement conditions on safety and to assess the effects of improving pavement friction on safety. Both wet- and dry-pavement crash rates presented a decreasing trend as skid resistance values increased. Thresholds in SCRIM coefficient values associated with significant decreases in wet-pavement crash rates were determined. Pavement friction improvement schemes were found to yield significant reductions in wet-pavement crash rates averaging 68%. The results confirm the importance of maintaining adequate levels of pavement friction to safeguard traffic safety as well as the potential of pavement friction improvement schemes to achieve significant crash reductions. PMID:19540980

Pardillo Mayora, José M; Jurado Piña, Rafael

2009-07-01

482

Predicting physical clogging of porous and permeable pavements  

NASA Astrophysics Data System (ADS)

SummaryPorous pavements are easily retrofitted, and effective in improving water quality and hydrology, but prone to clogging. Despite being a major determinant in the lifespan of porous pavements, there is limited information on the physical clogging processes through these systems. The aim of this study was to understand the main physical processes that govern physical clogging and develop a simple black-box model that predicts physical clogging. The key variables that were hypothesised to influence clogging were pavement design and climate characteristics. Two compressed time scale laboratory experiments were conducted over 3 years on three common porous pavement types; monolithic porous asphalt, modular Hydrapave and monolithic Permapave. Pavement design was found to be an important role in clogging. Permapave did not clog even after 26 years of operation in simulated sub-tropical Brisbane (Australia) climate while porous asphalt and Hydrapave clogged after just 12 years, from surface clogging and geotextile clogging, respectively. Each system was tested using two different dosing patterns: (1) continual wetting with no dry periods and (2) variable inflow rates with drying periods (i.e. representing more natural conditions). The latter dosing method approximately doubled the lifespan of all systems suggesting the influence of climate conditions on clogging. Clogging was found to be highly correlated with cumulative volume and flow rate. A simple black-box regression model that predicts physical clogging was developed as a function of cumulative volume and Brisbane climatic conditions. However it is very likely that the shape of this regression is general, and that it could be calibrated for different climates in the future.

Yong, C. F.; McCarthy, D. T.; Deletic, A.

2013-02-01

483

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 affecte